- Created: 28-10-20
- Last Login: 28-10-20
Description: How the Baseball Cap Went From Athletic Gear to Fashion Statement The “Philadelphia style,” with a sturdier brim, debuted in 1908, and was quickly embraced by major-league teams. Designers continued to tinker, as crowns grew higher and materials became sturdier. The advent of television—the first major-league game was telecast on August 26, 1939—brought a whole new audience to the sport and precipitated a rush of uniform redesigns and team relocations. By 1945 every team was wearing its own branded hat, and the accessory soon threaded its way into the hearts of children, especially those who played Little League and would take the look into adulthood. In the 1960s and ’70s, agricultural companies began embellishing their foam-front hats with company logos and cheap, plastic adjustable straps. Mesh backing also made the hats more breathable for workers, and long-haul drivers embraced these new accessories, inaugurating the phenomenon of the trucker hat. In the 1980s, New Era, the company that had supplied Major League Baseball for decades, started selling authentic team-branded hats to fans. Soon they were de rigueur. Tom Selleck’s character in “Magnum, P.I.,” set in Hawaii, wore a Tigers hat. You could see baseball hats on the cover of French Elle, in rap videos and atop the head of Princess Diana, whose occasional appearance in jeans and a baseball cap helped nurture her reputation as the “people’s princess”: It signaled approachability, even for a royal. And it worked for other luminaries as well. Steve Reich, a composer whose work has been played in some of the grandest halls in the world, and Paul Simon, one of the most successful pop musicians of the last 50 years, are both inseparable from rumpled, unbranded caps, even when they’re wearing black tie. No stuffy art-world or rock-star glamour here, the hats say. These are millionaires you could have a beer with. The Advantages of a Snapback Cap Adjustable Hats Fit Better There is one problem that many people have with fitted caps, and this is that they do not always fit very well. They are either a bit too loose, or a bit too tight, and the next size up or down is way too loose or tight. The caps that come in small, medium and large are just not always right for everyone. With a snapback, you can adjust it so that it is a perfect fit, which is going to make your hat really comfortable too. Adjustable hats are easy to adjust, and can be fitted to many different sizes quickly and easily. There are no buckles to jab into the back of your head or straps hanging out, and no Velcro for your hair to get caught up in. Show Your Team Spirit When people go to sporting events, they often wear clothing with the logos of their favorite teams to show their support. One great way to show your team spirit is to wear a snapback tap with the team logo on it. It is a lot less expensive to get a hat than other sports-related clothing items, such as jackets and shirts, and unlike these pieces of clothing, you can wear the same hat every day if you want, and no one is going to notice or even care. If you were to wear a team shirt every day, people will notice, so a hat is a much better way to be able to show your team spirit whenever you feel like it. Great Gifts If you are looking for a fun gift that will not cost a lot of money, an adjustable baseball cap is the ideal gift. If you have a sports enthusiast in your family, they will love getting a hat that has their favorite team's logo on it. The best part is, with a snapback cap, you never have to worry about whether or not you have gotten the right size, because it can be adjusted to just about any size. Trucker Caps Let Israelis Stand Out, but Not Too Much TEL AVIV—A craze for trucker cap in Israel this year is allowing people here to finally express themselves sartorially—and at the same time look just like everyone else. Israelis have an easy-going fashion sense that doesn’t much stick out in a crowd. Thanks to the lasting influence of the state’s founding socialist ethos, many avoid bold fashion statements. Among the nonreligious, plain T-shirts with jeans, or shorts when it’s hot, are the most common uniform. High-powered CEOs shun suits. The fanciest restaurants rarely have a dress code. ut the mania for the caps—preferably with an animal on the front—is giving Israelis an opportunity to express themselves, up to a point. Made by San Francisco-based hat maker Goorin Bros., the hats come embossed with different animals, often accompanied by a play on words. People choose which one they wear to offer a hint as to their personality. “It’s a hat with a presence,” said Amit Deutsch, a 36-year-old Tel Avivi, who sported a cap with a black panther, and had bought five of them at 150 Israeli shekels, or $46. “It’s become a type of icon.” Hodaya Elkayam, 23, who purchased a blue suede cap with an eagle and the word “America” in a Tel Aviv market on a sunny Friday afternoon, said the hats “have got style, they’re pretty and comfortable. So they’re good for all occasions.” RESERVED FOR PEOPLE WHO ARE NOT BLENDING IN In HBO Max's abortion road trip movie Unpregnant, Simonelli introduces Barbie Ferreira's character, Bailey — who's all of the above — wearing a purple angora Kangol bucket hat as she pops up over a bathroom stall divider. The hat's unexpected color and plushness, which match and clash with her shaggy green stuffed animal backpack, also help convey Bailey's innate but unintentional style. "I don't know if she's registered the cool factor that she has," adds Simonelli. Plus, her face-framing headwear was actually inspired by Ferreira serving her own outfit inspo in a textured white variation on Instagram. A nostalgic look back at the bucket hat icons of decades past really does run the gamut of individual style and creative talents. Simonelli references late-'80s hip-hop legends Run-DMC, the white cotton canvas classic of author and founder of the '70s gonzo journalism movement Hunter S. Thompson, and, of course, all the floppy and floral-accented toppers worn by Mayim Bialik in Blossom, which ran from 1990 to 1995. "Then you think of some of the late-'80s and '90s R&B singers, like Brandy, SWV, Missy Elliot, and Janet Jackson," says Smith, who also name-checked Blossom. "That cool sense of style that's laid-back and chill." During the early-2000s return of carefree teen pop, a trifecta of Mandy Moore, Jessica Simpson, and Britney Spears in the relaxed look, also come to mind. All About Knitted Hats Who knows when the first person decided to put something over their head to keep it warm, but knitters know that knitted hat is some of the most fun and easy things to knit. When they’re worked in the round there is little in the way of shaping, except when you get to the crown. Most hats are worked from the bottom up, with stitches cast-on and worked in a snug stitch pattern such as ribbing, or in stockinette for a rolled bring hat, using a smaller size needle than is used for the head portion of the hat. In many hat patterns, the hat is worked straight for the desired length of the crown, then nearly all of the stitches are evenly decreased over the course of just a few rounds. The yarn is cut, the tail threaded through the remaining stitches, pulled tight, and fastened off to the inside of the hat. The hat can be topped with a pom pom, i-cord, tassel, or whatever embellishment strikes your fancy. A great book for learning to make hats is Ann Budd’s Handy Book of Patterns, from which some of the material on this page is excerpted. There are chapters on basic hats as well as the type of hats called “tams.” There are several types of hats, but the most popular knitted hats are beanie-type caps, tams (sometimes called “berets”), slouch hats, earflap hats, and tuques. Beanies: These hats can be super simple or dressed up with a lace or cable patterns. In cooler climates, they’re wonderful gifts for knitters to make. Tams/Berets: There are so many different stitch patterns to use in this style. Tams and berets can be plain stockinette or intricate Fair Isle. This style of hat is really flattering on just about every face shape, too. Earflap Hats: These hats are popular in cold climates. They’re great for keeping ears warm and they’re fun to knit. The knitters of Peru specialize in these hats, as shown in the photo at right. THE HISTORY OF THE STRAW HAT Reaching for a straw hat to complete our seaside look—or frankly, any summer outfit—is as instinctive to us as say, oh I don’t know, breathing. Next to sunglasses, it’s one of the most obvious accessories to use as protection against the sun’s harmful UV rays, but its origins are less than clear. When an item is as ubiquitous as that of a straw hat, it’s virtually impossible to determine its original maker or even pinpoint the first documentation of its existence. (Fun fact about hats: Historians believe that some type of head-covering piece—as protection against inclement weather—was the first article of clothing ever worn by humans.) Straw hats—distinguished by their woven makeup of different types of straw or fibers similar in texture and strength, like braided hemp, raffia, and jute—are believed to have been worn in Europe and Asia as early as the 15th century (after the Middle Ages). In most countries in Asia, including Japan, China, Indonesia, Malaysia, and Vietnam, rice paddy workers topped their heads with conical-shaped hats to shield themselves from the sun and the rain, though legend in Vietnam has it that the hat, or nón lá in Vietnamese, originated from when a goddess descended from the sky wearing an enormous hat made of four large leaves held together by bamboo sticks, which protected the people from a torrential downpour. In the Très Riches Heures du Duc de Berry, the most famous surviving example of an illuminated French Gothic manuscript created from 1412 to 1416, short-brim straw hats are shown mostly worn by men. Though by the 1700s, French women wore straw bonnets and in the 1800s, European paintings all depict women posing for portraits in ribbon-adorned floppy straw hats and floral-strewn ones with an upturned brim. Vincent Van Gogh even immortalized his straw hat in a self-portrait in 1887. The first cowboy hat—made of straw, might we add—was invented by John B. Stetson in 1865, and the silhouette basically remains unchanged to this day. By the late 1800s and early 1900s, straw hats were embraced by everyone. But it wasn’t until President Theodore Roosevelt’s 1906 visit to the Panama Canal—when he was photographed at the construction site in his pale suit and Panama hat—that the accessory catapulted to fame. Light in weight, the summertime staple exuded equal parts casual and polish; by 1944, it became Ecuador’s number-one export. Conclusion As an experienced manufacturer and supplier, in addition to the above hats, we also provide various other types of caps and hats, such as children's baseball cap,knitted hats, straw hats and so on.
Publish Date: 28-10-21
Description: A modern party speaker with exhilarating acoustics Sony recently launched in India the Sony SRS-XG500 party speaker. Though it reminded me of the old boombox music players, it is by no means a retro one but a modern party speaker with a powerful output and wide connectivity options. Although bulky, the SRS-XG500 is a moveable party speaker that is easy to manage irrespective where you throw a party. Priced at Rs 32,999, the speaker seems to be on the expensive side. Is it? Let’s find out: Build and design Sony SRS-XG500 party speaker The cylindrical body gives the speaker a distinct look while the fabric covering brings minimalism. The big handle is sturdy enough for us to carry it anywhere. On the front, there are buttons for power, Bluetooth, volume, play/pause, and a bass boost button. A rubber lid at the back covers power and USB ports and a connector for plugging in a guitar. The two large rubber feet keep the speaker stable when the bass comes in. The sides have LED lights that change colour when you play music and it looks absolutely beautiful under dim or low light. The Sony SRS-XG500 weighs nearly 5 kg but quality material is used so weight isn't much of a factor to point out. The audio quality of the Sony SRS-XG500 is at par with most of the small-sized trolley-style audio speaker, although it has its own limitations considering it is a portable speaker. That said, the sound is loud and bassy, but at the same time, highly balanced so it will be music for your ears. For bass lovers, there is a bass boost feature but honestly, the default sound is much better because of the balance. The feature to connect a guitar adds to its credentials as a party speaker. You can also connect the SRS-XG500 with other speakers using Party Connect. There are slight tweaks you can do with the sound and light settings using the Sony Music Centre app. I had to play with the equalizer as the default sound at times doesn't go well with all genres of music. Overall, the experience was fine as I played songs on full volume on the terrace. The Sony SRS-XG500 offers up to 30 hours of playtime on a full charge. The battery fares well in real-life scenarios and the backup is close to that Sony claims. The SRS-XG500 is water and dustproof with the IP66 rating, so a slight rain or splash of water and everyday dust won't harm the speaker. The Sony SRS-XG500 is a speaker with loud and enthralling audio out. Although bulky, it can be taken anywhere - from terrace to park for an enhanced musical experience. The SRS-XG500 brings all the features a modern party speaker should have, not to forget about Sony's signature sound that lights up the party, but at Rs 32,999, it's quite expensive and people may prefer cheaper alternatives that JBL and other brands offer. Throwing a party anytime soon or planning to attend one? Conventionally, partygoers used to have a big music system with bulky speakers to ensure everyone is able to enjoy the melody. Thanks to technology upgrades, today, you can do so by carrying a small yet powerful fire light speaker. In the last decade, the trend of party speakers has seen a big spike. With increasing workload, people are now taking every chance they get to loosen up with friends and crank up their favorite music. Incomes party speaker with fire light. Be it a house party, a beach party or even better, a pool party, party speakers are always going to lighten up your guests with incredible sound effects and thumping bass. These are small, portable, and quite powerful. Yesterday I was writing about the perils and stigma of hearing loss, sometimes caused by listening to loud music. Today I’m reporting on speakers that produce loud music. Hopefully, the two aren’t mutually exclusive because when listening to music in larger rooms or out of doors, you do need more volume. Sony is building a name for itself in the growing market for large bluetooth speaker. Today it’s announcing the launch of three new models designed to get any party going with a swing. Marketed with the slogan “Life should be lived at full volume” Sony wants you to turn up the music to full volume and dance away the night with clear and rich sound. Sony’s new range of X-Series speakers is specially designed to provide a powerful and wide-spreading sound that will suit almost any genre of music. Whether you’re listening indoors or outdoors, by yourself or with a group of friends, the new X-Series speakers come in a range of styles and choices of sound quality, portability, durability and lighting. All the new models s feature Sony’s innovative X-Balanced Speaker Units. Featuring a non-circular diaphragm, the drivers create more sound pressure and have lower distortion by maximizing the area of the speaker. The upshot of this, claims Sony, is a richer and clearer sound whatever style of music is being played. The new Sony XP700 has three front high-efficiency tweeters and one rear high-efficiency tweeter delivering an omnidirectional sound that Sony says has a punchy and deep bass with plenty of clarity. The new XP500 and XG500 speakers have two front high-efficiency tweeters while the XG500 model includes passive radiators that are optimized to reproduce a clear bass. Whether you’re looking for something to use on the go or in the shower, a portable speaker will play any music, podcasts, or audiobooks a lot louder (and a lot clearer) than the one that comes with your phone or laptop. And while we’ve written before about lots of audio accessories — including the best noise-canceling headphones, wireless headphones, and workout headphones — here, we’ve rounded up the best portable speakers, as praised by the most enthusiastic reviewers on Amazon. Over 53,000 reviewers give this Anker speaker five stars, with thousands particularly impressed with its 24-hour battery life. “Oh my God, it lasts forever,” says one reviewer. “I’ve charged it once since I got it (a week ago) and used it every day for at least a few hours.” Another calls it “RIDICULOUS. I gave it a full charge and got over a week play time while playing via Bluetooth at around five presses below max volume for about ten hours a day.” And while the battery might be on par with the original Soundcore model, this newer model — called the Soundcore 2 — has several upgrades. It has 12-watt speakers instead of six-watt ones, which leads to a beefier sound overall. “I have the original Soundcore, which was an excellent little gadget until I finally blew a little speaker playing it louder than recommended, repeatedly, for years,” one says. “This SC2 is also excellent. It does put out more sound and the base is fuller.” This model is also waterproof, which increases the number of places you can port this speaker to. “This little speaker has taken on the Atlantic Ocean, Moriches, and Great South Bay with no problem at all,” says one fisherman. “Swells of huge waves have soaked this speaker and it just keeps working.” This under-$20 speaker received high marks from over 19,000 five-star reviewers for its sleek design and surprisingly powerful sound. “This is the most fantastic Bluetooth speaker I have ever purchased and I have purchased a lot,” says one such reviewer, who goes on to say that the sound is “gorgeous,” and the controls are “incredibly easy and intuitive. I might even add slick. I have no idea why they are selling at this price.” Another reviewer was looking for a small speaker to carry while on the go, but they were “pretty skeptical about this little $15 speaker being that great.” As it turns out, “this little speaker packs BIG POWER,” they write. “I can’t believe the volume level. I have a much bigger 808 Audio Bluetooth speaker that cost much more and has half the sound.” While the reviewer admits you’re “not gonna be bumping bass with this little dude,” they say it “gets the job done well” for streaming videos and music. And ultimately, for under $20, “if it does break, I won’t mind buying another one.” “360-degree sound is extremely innovative and the best part of this product, as it essentially solves the problem that most portable speakers have, which is the volume level being too loud for some people and not loud enough for others,” one reviewer says, explaining the appeal of the unique design of this Bose speaker. They add, “With music coming from all sides of this speaker, everyone is hearing the same level of music and you can have it loud enough to be enjoyed but not worry about it overpowering someone else.” Other companies make similar style speakers, but one user says this one from Bose is above the rest. “If you have owned a 360-degree speaker under a hundred bucks and then upgrade to this one,” they write, “WOW, what a difference. I own the Soundcore Flare also; it sounds good, but you get what you pay for. The lows are much more pronounced on the Bose along with much fuller sound.” It’s a sound so full it’s enough to power a party. “Used for the music at our outdoor wedding ceremony,” one writes. “All 120 people could hear the music just fine.” Like our best rated pick, also an Anker speaker, this model has an impressive 24-hour battery life. “Great little speaker — especially for the price,” one says. “Sound is crisp and full, it looks great, and has a nice, solid heft to it. It’s also extremely easy to pair to an iPhone. Once paired, it quickly and reliably connects to my phone when turned on.” Another asks, “Is it the utmost in premium quality sound? Of course not, don’t be an idiot, it’s a tiny speaker that costs under $30.” But they find it impressive nonetheless: “I think you would be hard pressed to find anything at this price point that comes anywhere even remotely close to the awesomeness you get with this speaker.” Many of the thousands of reviewers call out the long battery life, including one who describes it as, “stupid-good … I have literally left this thing on for days — DAYS — and it still had juice.” Another says “I have only charged it once and have likely played it for a total of 4 hours over the last week (Bluetooth) and the battery still says 100 percent.” And when it comes to portability, reviewers say it can hold up to most environments. Reviewers use this in the bathroom, the car, and even on motorcycles, which leads one to say it’s pretty durable: “I’ve dropped this thing onto the street from a speeding motorcycle — the speaker didn’t even stop playing.”
Publish Date: 26-10-21
Description: Packaging Machines Dust-extraction systems were attached to the packaging machines, the sugar screening equipment, and the mills for powdered-sugar production, to remove sugar dust. The dust-extraction ducts were connected to dry dust collectors. However, it was found that the maintenance of the dust-collection system had been poor. In addition, some equipment was significantly undersized or incorrectly installed. Some dust ducts were found to be partially, and in some locations, completely filled with sugar dust. The plant had hired an outside consultant to evaluate airflows, pressure drops, and other operating parameters on both the dry and the wet dust-collection systems. The report identified numerous design and maintenance deficiencies. Because the report was delivered only a few days before the 2008 catastrophe, there had been no opportunity to review or act on it. In addition, during the investigation following the 2008 catastrophe, it was found that sugar conveying and processing equipment were not adequately sealed to prevent spillage of significant quantities of sugar onto the adjacent floors. Less than 2 months before the catastrophe, an internal inspection by company supervisors and quality assurance personnel learnt that many tonnes of spilled sugar had to be removed from the floors at intervals and returned to the refinery for reprocessing. Packaging operators and other employees also reported significant amounts of sugar dust escaping the packaging equipment into the working areas. The systems for conveying maize starch to be mixed with the granulated sugar, the grinding mills, and the powdered-sugar vertical packing machine all generated significant quantities of sugar dust and maize starch in the work area. Workers reported that airborne sugar dust and spilled sugar in the powdered-sugar processing and packaging work areas were a constant problem and that significant accumulations were often seen on equipment and on the floor. One worker told that he used a squeegee to clear a path on the floor through spilled powdered sugar to get to equipment he operated during his shift. Packaging equipment unwinds materials from its roll, forms it into the shape of a container, fills it with product, and seals the container. Printed material should, of course, reflect the container’s length (the “cutoff”) and its width (the “web”). Web and cutoff can be no more precise than as initially printed, but any subsequent web handling can introduce additional variability to both. Slitting defines a roll’s edge that must parallel to the machine direction of the printing process. Figure 6.1 suggests the challenge. Three impressions on the right have a light-colored border and three on the left have a darker border. Slitting between the third and fourth impressions (cut No. 3) is likely to produce a wavy line with alternating strips of either color. They would appear on the right edge of the third roll and left edge of the fourth roll. When print extends to (and through) a slit edge as in Figure 6.1 (called a “bleeding edge”) its color must be uniform for a width at least as great as the side-to-side tolerance of the slitting operation. Once the contract has been agreed, the processes of design and construction may commence. These lead to the manufacturing site acceptance trials, which would include a full validation of all the operational requirements of the machine. The final stage is delivery, installation and commissioning, at which the performance of the machine is assessed to ensure that the required operational performance has been achieved. A rather unusual application of rigid PVC involves building apparatus from machined parts, largely because the polymer is very easy to machine into complex and intricate components. A company in Coventry had the idea of building a type of transparent film packaging machine using such PVC components to produce the wrapping action needed. Their concept included incorporating water-cooling channels within the PVC parts to control the process. They built a working prototype using a combination of light alloy components, slab PVC and acetal bearings (Fig. 6.17), and relied on a toolmaker to machine the various PVC parts and solvent welding the parts together to make the inner water-cooling channels. However, when the wrapping machine was first switched on in 1998, numerous leaks occurred from the PVC components and rendered the process inoperable. The forming process on a horizontal packing machine requires conformance of printing to the expected machine sequence. The issue is a recurring one for printed rolls of any material for any handling process. To communicate expectations, the printing industry (not only flexible packaging) uses standard designations for print orientation on a roll (Figure 6.2). Eight orientations are described. Numbers one through four refer to printing wound to read from the outside of the roll; five through eight refer to printing wound inside of the roll. The four numbers of each set refer to the orientation of the printing relative to the leading edge of the unwinding roll, top, bottom, right, or left. The plastic packaging company sued the toolmaker for their losses. I was asked to examine various parts and report on the root cause of the problem. One particular part was chosen for close scrutiny. It was a bar 640 mm long with a section of 39 by 20 mm and when examined, proved to be slightly curved, being about 2 mm out of true. The bar had been solvent welded to form the water channel which ran along its length and was drilled at either end (inner diameter about 8.5 mm) to accept the water supply. Macroscopic inspection showed that the joint between the two halves exhibited a small gap of about 0.6 mm (Fig. 6.18). The same picture shows cross-threading on the upper part of the screw thread, which no doubt was caused by numerous attempts to discover the source of the leak or disconnect the supply to stop the leakage. Since the water pressure was about 2.6 bar or 38 psi, the inner source of the leak was established. External examination showed a similar problem, with similar sized gaps in the joint (Fig. 6.19), and since the bar had leaked here in service, a path between the two gaps was present. No doubt the many other leaks in the system were caused in a similar way by poor joints. After pressing, the garment should be free from wrinkle and creases, and have a good shape. Apparel needs to be stored and packed for delivery to the potential customers. Nowadays, there are manual or semi-automatic small packing machine available in the industry, but careless or inappropriate storage and packaging will cause a deterioration in the appearance of the final product. The pressed apparel should be stored in a cool, dry place. The storage should have sufficient room to accommodate the apparel without being too closely packed, which could not only cause wrinkles in the apparel, but also block the air circulation (causing a moisture build-up leading to mildew on the apparels), or result in excessive heat causing the plastic bags to bond to the fabric. Also, the storage area should be as clean as possible so that dust and dirt, the acid pressure in atmospheric pollution, as well as the presence of moths or other pests, do not cause apparel to deteriorate during storage. Apparel in storage should not be subjected to any strain or movement that could cause the fibres to become weak and break. Avoid pressing in sharp folds. Different types of apparel should have different conditions of storage and packaging. Knitted or stretched apparel should preferably be folded rather than hung, and should be stored in a plastic bag. Nylon hosiery should be stored and packed in plastic bags to prevent snagging. Sweaters should also be stored in plastic bags to keep them from becoming contaminated by lint. Clothing containing wool should be stored in a moth-free or mothproofed place (Finch and Putnam, 1977; Fan and Hunter, 2009). Various kinds of machinery are employed in food and pharmaceutical processing. A plant may have a variety of tanks, fermenters or bioreactors, pumps, valves, centrifuges, homogenizers, heat exchangers, evaporators, spray dryers, and packaging machines, as well as other devices. A vessel may have internals, such as agitators, ports for sensors, shafts and mechanical seals, mechanical foam breakers, baffles, and gas spargers, all of which have an impact on cleanability. Irrespective of the type of equipment, all plant components for food and pharmaceutical processing should be CIP capable. Equipment design should ensure that all surfaces that in any way contact the product, including vapor, foam, and sprayed or splashed material, receive cleaning solutions during CIP. For example, a submerged culture fermenter may need to be supplied with CIP solutions at multiple points to ensure proper cleaning. In addition to being sprayed in the vessel, the CIP solutions may have to be sequenced through the submerged aeration pipe, the air exhaust lines that may be contaminated with fine culture droplets and foam, the mechanical foam breaker, and the various supply lines for the medium, inoculum, antifoam agents, and pH control chemicals, as well as any harvest lines. Cleaning of the sample valve and any retractable probes will require attention. Similar specifics need to be evaluated during the design of other process items and in planning a CIP scheme.
Publish Date: 26-10-21
Description: Yoga Equipment Guide for Beginners When you first start doing yoga, it's hard to know what you really need to buy. The yoga mat continues to develop so much clothing and equipment that you might feel you need to spend hundreds of dollars before ever stepping foot in a studio. The good news is, you actually need very little to get started. That said, if you're starting a home practice, or you'd feel better purchasing yoga-specific apparel and equipment prior to your first class, here's what you need to know. It should go without saying that most aerial yoga accessories want you to wear something to class, but you don't need scores of printed yoga pants or designer gear to be accepted by your peers. Start with the comfortable, breathable athletic apparel you already have on hand, and purchase mid-level basics for anything you're missing. Pants or Shorts: You can't go wrong with a few pairs of solid-color yoga pants in black, dark grey, navy, or brown. You can mix-and-match these tights with a wide variety of tops, and if you purchase high-quality options, they can last a long time. If tight pants aren't your thing, look for jogger-style pants or the popular harem-style pants that have elastic around the ankles. These pants are stretchy and offer a little extra room, but due to the ankle elastic, they'll stay in place throughout your practice. Shorts are a popular option for guys, and they're also appropriate for women, especially if you plan to try hot yoga. Just keep in mind, you may want to wear form-fitting spandex shorts or looser shorts with connected tights underneath because some poses require you to position your legs in a way that could leave you uncomfortably uncovered with looser, running-style shorts. Tops: It's important to wear tops that are fairly form-fitting so your shirt doesn't fly over your head during forward bends. Wicking material is helpful, especially if you tend to sweat a lot or if you plan on attending a hot yoga class. Because yoga rooms are sometimes kept cool, you may want to bring a light cover up or sweater with you to class. You can wear it until class starts, and if you keep it by your mat, you can put it on before the final savasana. Sports Bras: If you're a woman, make sure you wear a sports bra. While TPE yoga mat tends to be a low-impact activity, a decent sports bra can help keep your "girls" in place as you transition between poses, making your practice more comfortable. Hair Ties or Headbands: Whether you're a man or woman, if you have long hair, you need to secure it in place before you start class to prevent stray locks from falling in your eyes and face. A basic hair tie or headband should do the trick. Yoga Socks: To be clear, yoga socks are not a requirement to attend a class. In fact, it's preferable to do yoga barefoot. That said if you can't fathom the thought of taking your socks and shoes off in front of strangers, invest in a pair of yoga socks with grips on the bottom so you can keep your feet covered while maintaining good traction. Standard socks absolutely won't do, as you'll end up slipping and sliding all over your mat. These days, you can buy yoga apparel practically anywhere, and it's not unusual to see yoga pants priced at over $100. Don't feel you need to lay out that much cash for a single pair of pants! Target, Amazon, and YogaOutlet offer quality options for well under $50. Buy a couple pairs of pants and a few tops, and you'll be set for months. As you commit yourself to your practice, you may decide to add trendy prints or styles to your wardrobe. In gyms and yoga studios, it’s commonplace to use a yoga mat, also called a sticky mat. The mat helps define your personal space, and, more importantly, it creates traction for your hands and feet so you don’t slip, especially as you get a little sweaty. The mat also provides a bit of cushioning on a hard floor. Most gyms provide mats and studios have them for rent, usually for a dollar or two per class. This is fine for your first few classes, but the disadvantage to these mats is that lots of people use them and you can't be sure how often they're being cleaned, so you may consider buying your own. Premium yoga mats can be expensive, often around $80 to $120, but it's possible to find a starter mat for as little as $20 from retailers like Target and Amazon. Just keep in mind, if you decide to buy a cheaper mat, you'll probably find yourself replacing it in short order if you use it often. If you're really ready to commit to a yoga practice, your mat is one place it's worth it to lay out some cash. Decide which mat features are important to you—for instance, length, thickness, material, durability, comfort, traction, or how to keep it clean—then buy a mat with good reviews based on your needs. Manduka and Lululemon are known for the quality of their Pro Mat and The Reversible Mat, respectively, but other brands, including Jade and Yellow Willow, also offer high-quality, durable mats with good traction and support. Yoga props are a boon to a fledgling suede yoga mat practice. Props allow students to maintain the healthiest alignment in a range of poses as the body bends, twists, and opens up. They also help you get the most out of each pose while avoiding injury.1 You should familiarize yourself with the props described below, but you don't need to buy your own (unless you're starting a home practice) because they are almost always provided by studios and gyms. Mat Bags or Slings If you own your own yoga mat, and you're going to be lugging it back and forth to the studio on a regular basis, there's a legitimate case to be made for purchasing a mat bag or sling. These accessories do exactly what they suggest—they make it easy for you to sling your rolled mat over your shoulder without it coming unrolled. Slings usually use velcro straps to bind your mat in its rolled configuration with a connecting strap you can throw over your shoulder. Slings sometimes offer additional pockets for storage, but not always. Bags, on the other hand, typically come in one of two styles. One version uses velcro straps to keep your rolled mat secure against a larger gym bag. The other version is essentially a snap- or zipper-closure bag specifically designed to hold your rolled mat. Both styles provide extra storage for clothing, wallets, cell phones, and the like. The style and brand you choose really comes down to personal preference and budget, as slings can cost as little as $10, and heavy-duty bags can cost well over $100. For variety, check out YogaOutlet, where you can find an array of brands at reasonable prices. Blankets Yoga studios usually have stacks of blankets available for students to use during class. Grab one or two blankets at the beginning of class. Folded blankets can be used to lift the hips during seated poses, or to offer support during lying poses. For instance, when you sit cross-legged, you can place a blanket under your sit bones to elevate the hips above your knees. Blankets come in handy for all sorts of things during class, and if it’s chilly, you can use them to cover up during the final relaxation. For a home practice, there's truly no reason to purchase new blankets. Simply use what you already have on hand around the house. If, however, you don't own any extra blankets, YogaOutlet offers them for as little as $13. Blocks Like blankets, yoga blocks are used to make you more comfortable and improve your alignment. Blocks are particularly useful for standing poses in which your hands are supposed to be on the floor. Placing a block under your hand has the effect of "raising the floor" to meet your hand rather than forcing the hand to come to the floor while effectively compromising some other part of the pose. This can be seen in half moon pose. Many people don't have the hamstring flexibility or core strength to hold the position with proper form. By placing a block under the hand that's reaching toward the floor, it's easier to keep the chest open and torso strong. Without the block, the chest might be inclined to turn toward the floor, the supporting knee might be inclined to bend, and the torso might be inclined to "collapse." The simple use of the block helps maintain proper alignment. Yoga blocks are made of foam, wood, or cork. They can be turned to stand at three different heights, making them very adaptable. If you plan to do a lot of swivel at home it's worth it to get a set of blocks (helpful for poses where both hands are reaching toward the ground). If you're going to attend classes, blocks will be provided for you. The good news is, almost any block is sufficient, so this is an area you don't have to worry too much about scrimping on. But slightly wider blocks—those that are at least four-inches wide—provide better stability. YogaOutlet and Amazon offer several sizes and styles for under $10 each. If you're willing to pay a little more, Yoga Hustle offers some fun options for $24 a pop. Straps Yoga straps, also called belts, are particularly useful for poses where you need to hold onto your feet but cannot reach them. The strap basically acts as an arm extender. For instance, in pascimottanasana, if you can't reach your feet with your hands in the seated forward fold, you can wrap the strap around the bottom of your feet and hold onto the strap to maintain a flat back instead of slumping forward. Straps are also great for poses where you bind your hands behind the back (marichyasana, for example). If your shoulders don't allow enough flexibility for the bind, you can use a strap to "connect" both hands without excess strain. And with the strap's help, you can move your hands toward each other over time to make progress toward the full bind. You probably have something around your house that would work as a strap (like a belt or even a towel) and yoga studios supply them for use during class. That said, if you really want to buy an official version, it's hard to beat the price of YogaOutlet, where you can find straps for under $10. Bolsters Bolsters have many uses for yoga students. You can use them in place of a stack of blankets to make seated and forward bending poses more comfortable. You can place them under your knees or your back when reclining for support and passive stretching. They are particularly handy in restorative and prenatal yoga classes. If you take this type of class, the bolsters will be provided. If you want to do restorative yoga at home, it may be worth it to invest in your own bolster. The are two basic bolster shapes: round and flat (more of a rectangular shape). Flat bolsters tend to be more ergonomic; however, round bolsters can be useful when you want more support or a deeper stretch. It comes down to personal preference. If you have the option, use both styles in class before you decide which one best suits your home practice. Amazon is the best place to shop for sheer variety and price, but if you want a pretty bolster, check out Hugger Mugger, Inner Space, or Chattra. The prices are in line with the marketplace ($40 to $80), and the designs are bright and beautiful. Wheels Yoga wheels are a relatively new prop starting to gain a foothold in the yoga studio. These wheels are roughly 12-inches in diameter and are about four-inches wide. When set upright, you can lie back on the wheel or place a foot or hand on top of the wheel to deepen your stretches and enhance flexibility, slowly rolling the wheel farther as you relax into each stretch. Wheels can also be used in more advanced practices as a way to challenge stability or to offer support during challenging poses. While it's unlikely that you'll need a yoga wheel as a beginner, you may want to consider a purchase down the line. Most wheels range in price from $40 to $60. Yoga Design Lab, for instance, offers one for $48.
Publish Date: 25-10-21
Description: Design and Analysis of a Novel Tension Control Method for Winding Machine The filament winding technique has evolved in recent decades moving from classical lathe-type towards winding with an increased number of degrees of freedom using more complex equipment. These advancements complicate the selection of an optimum toroid winding machine set-up for the realization of particular winding methods and correlating part designs. This is further complicated by the variety of approaches. In order to investigate existing equipment technologies regarding feasibility, operational and economic aspects, different filament winding equipment is established in an experimental environment. Thereby advantageous solutions can be assigned to particular winding methods and the selection of appropriate filament winding equipment is facilitated. Filament winding has emerged as the main process for carbon fiber reinforced plastic (CFRP) fabrication, and tension control plays a key role in enhancing the quality of the winding products. With the continuous improvement of product quality and efficiency, the precision of the tension control system is constantly improving. In this paper, a novel tension control method is proposed, which can regulate the fiber tension and transport speed of the winding process by governing the outputs of three different driven rollers (the torque of the unwind roll, the torque of the magnetic powder brake roller, and the speed of the master speed roller) in three levels. The mechanical structures and dynamic models of the driven rollers and idle rollers are established by considering the time-varying features of the roller radius and inertia. Moreover, the influence of parameters and speed variation on fiber tension is investigated using the increment model. Subsequently, the control method is proposed by applying fiber tension in three levels according to the features of the three driven rollers. An adaptive fuzzy controller is designed for tuning the PID parameters online to control the speed of the master speed roller. Simulation is conducted for verifying the performance and stability of the proposed tension control method by comparing with those of the conventional PID control method. The result reveals that the proposed method outperforms the conventional method. Finally, an experimental platform is constructed, and the proposed system is applied to a gear toroidal winding machine. The performance and stability of the tension control system are demonstrated via a series of experiments using carbon fiber under different reference speeds and tensions. This paper proposes a novel tension control method to regulate the fiber tension and transport speed. High modulus carbon fiber is an excellent industrial material, which is widely used in several fields such as satellite supporting cylinder, shells of rocket engine, and solar array. The composite manufacturing process is the key to the application of carbon fiber. Filament winding has emerged as the main process for fabricating composite structures. It is widely used in building rotational parts. In the filament winding process, the carbon fiber is delivered from the unwind roll and passed through the resin bath to mix with resin under different temperatures and finally wrap around the surface of the mandrel in the designed pattern. The major specifications that should be satisfied during the winding process are the winding line type and the fiber tension, which are considered to be the key factors related to the tensile strength of the fiber products. The winding line type is determined using the numerical control system, so this paper focuses on the tension control problem during the winding process. Researchers have shown that unstable tension may lead to loss in strength of fiber winding products . Therefore, fiber tension should be maintained at the reference value during the winding process for ensuring the product quality. Several factors shape the tension control design to be challenging, which include significant parameter variations and disturbances. Small variations in the change of velocity of the transport rollers can cause significant variations in tension. On the other hand, we used different shapes of mandrels for maintaining the line speed in acceleration or deceleration states. Because of the coupling between the tension and the line speed, it is difficult to maintain the tension at a desired value. Researchers have investigated considerably for acquiring better control result. Lee et al. used a magneto rheological brake to provide back tension to prevent frequent part changes and fatal malfunction for a tension control system, and a PID controller was designed, and test results showed the feasibility with satisfying the time constant and the allowable error. Nishida et al. divided the transport system into several subsystems and a self-tuning PI controller with an estimator based on a novel adaptive particle swarm optimization method was constructed to solve the strong coupling between the velocity and tension of the web. A self-tuning PID controller to control the tension for tape winding of composites was designed and the constant extension ratio is guaranteed. To reduce the time required for the stabilization of the tension, a faststabilization method for web tension is proposed. The model of dancer system and stabilization of web tension in drying process are established, and the variation of tension is used as a reference value for the tension stabilization. The integration of load cells and active dancer system for printed electronics applications was used to improve the accuracy of web tension, and self-adapting neural network control was proposed to reduce tension spikes due to the change in roll diameter of winder and unwinder rolls. Wu et al. developed a tension detection and control mechanism and analyzed the main causes of wire tension variation, and then a PI algorithm was proposed to reduce tension variation. An accurate dynamic model for the unwind roll by considering the time variation of the roll inertia and radius was developed, and a decentralized controller for computing the equilibrium inputs for each driven roller was proposed . A sliding mode control with guaranteed cost technique was applied for reducing the system uncertainties. The simulation results showed that the proposed method had good robustness and quick response time. Compensation method by calculating the torque of a driven loop lifter was developed to control the tension and thickness of hot-rolled strip. For the control strategy, several control methods have been proposed including disturbance rejection control , neuro-fuzzy control , and H∞ control . Choi et al. conducted a survey on various types of control algorithms by investigating their strengths and weaknesses, and demonstrated some areas of potential future development. Most of the above studies considered the dynamics of driven rollers in the models but the behavior of idle rollers was ignored. Consequently, the models were under some limited conditions, which ignored detailed complex tension dynamics. On the other hand, most research focused on dynamic modeling and control strategy design, but the mechanical structure and the influence of parameter variation on fiber tension were ignored. In this paper, a novel tension control method is presented, which can regulate the tension and speed of the filament winding process. The mechanical structure and dynamic model of the system are established, and the influences of the parameter and the speed variation on fiber tension are examined. Subsequently, according to the features of driven rollers and the influence of variation, the control method is proposed by regulating the outputs of the torque of unwind roll, the torque of magnetic powder brake roller, and the speed of the master speed roller in three levels. Simulations are conducted for verifying the effect by comparing the results with those of the conventional PID controller. Finally, the performance of the proposed control system is verified through experimental studies using a filament slider coil winding machine. The structure of the paper is organized as follows. Section 2 presents the mechanical structure of system. In addition, the dynamic models are constructed, and the influence of parameter and speed variation on the rollers is examined. In Section 3, the control strategy is proposed. Simulations are conducted for verifying the effect of the proposed controller by comparing with that of the conventional PID controller in Section 4. In Section 5, the proposed mechanical structure and control strategy are applied to a belt head winding machine, and the experimental study is conducted for verifying the performance of the tension control system. The process line is divided into three zones (Figure 1): the unwind section, the process section, and the rewind section. In each zone, one or two rollers are driven using motors for transporting the carbon fiber from the unwind roll to the rewind roll. The carbon fiber is delivered from the unwind section to the process section, which consists of the magnetic powder brake roll, the master speed roller, and some idle rollers. In the process section, the carbon fiber passes through the surface of the master speed roller. As the carbon fiber is comprised of thousands of threads, the resin is properly pasted on the surface of the carbon fiber. The master speed roller is driven using an AC servomotor, and the speed is controlled for acquiring the desired speed and tension. The rewind section consists of a four-axis CNC system for acquiring the winding pattern. The control method of hook type winding machine is shown in Figure 2 in three levels. The control system can regulate the tension and speed of the filament winding process by governing the output of three different driven rolls—the torque of the unwind roll, the torque of the magnetic powder brake roller, and the speed of the master speed roller. In the first level, the unwind roll, which is driven using a torque motor generates a reverse force for applying a pretension to the carbon fiber. The pretension is set at a small value because large tension will cause the tension to deviate from the set point owing to the time-varying radius and the disturbance caused by the periodic swing. In the second level, the magnetic powder brake generates another pretension to the carbon fiber. The feature of the magnetic powder brake is to generate torque in a wide range without introducing considerable tension interference. However, its disadvantage is that the accuracy and response speed are inadequate than the speed control using the AC servomotor. Finally, in the third level, as the tension is close to the set value, the master speed roller is controlled for acquiring the desired tension. On one hand, the speed of the master speed roller traces the line speed of the carbon fiber as the reference speed. On the other hand, the speed is adjusted for maintaining tension at a desired value. The response speed is high when the AC servomotor operates in the speed control mode. Consequently, when the line speed of the carbon fiber changes rapidly or in the start-time period, the master speed roller maintains tension in a small range. The control system measures the speed and tension of the carbon fiber, and then controls the multivariable output of the torque of the unwind roll, the torque of the magnetic powder brake roller, and speed of the master speed roller. The mechanical structure and dynamic modeling of the system is presented as follows.
Publish Date: 25-10-21
Description: Flexible Metal Hoses: An essential guide A metal flexible hose is a type of piping used to connect two distant points to transport or transfer fluid. In Oil & Gas applications hoses are used when there is a considerable relative movements. A variety of fluids and fluidized solids can easily be transferred through flexible hoses to other locations. These are most commonly known as hosepipe. Along with loading and unloading services in processing plants, these are widely used by homeowners as garden hose. Normal Flexible hoses are made of non-metals like soft plastic material or synthetic rubber. However, flexible hoses of chemical industries that are designed to absorb pipe movements are made of metallic materials. Flexible hoses are moade by extrusion or vulcanization process. To add strength to the non-metallic flexible hoses, they are reinforced using a crisscrossed grid of fibers combined together through braiding, spiraling, or knitting. These reinforced hoses can be long enough. Basically, flexible hoses have four parts; inner tube, reinforcement, End fittings and protective outer cover. A corrugated hose is constructed with a bellow of very long length. Fundamentally, the behavior of a corrugated flexible hose is the same as the bellow expansion joint. The flexible hose has to resist the hoop pressure stress, but cannot sustain the longitudinal pressure stress. Also, it has a tendency to squirm under internal pressure. To resist the longitudinal pressure stress and prevent squirm, corrugated hoses are often constructed with braids wrapping around the outside surface as shown in Fig. 4. The braided cover also protects the corrugation from scratch and wear. The braided hose, similar to a tied expansion joint, cannot accommodate any axial movement. On the other hand, the un-braided hose can sustain very small internal pressure. Due to the lack of a limiting mechanism, a corrugated tube connector metal flexible hose is prone to abuse. It should not be bent beyond its acceptable range. For braided hoses, the situation is even more critical. As the corrugations are not visible from the outside, a braided hose does not show immediately when damaged. Therefore, for manual handling in such situations as loading/unloading and switching operations corrugated hose is not suitable. The corrugated flexible hose has a continuous metal wall thus making it pressure-tight. It is suitable for handling any type of gas and liquid as long as it is compatible with the hose material. An interlocked hose is constructed with links that are kept tight with packing material. There are clearances provided between the links that afford the capability of accommodating some axial movement. As the hose is being bent, the clearances gradually close. The hose becomes stiff and cannot bend any further at a certain point when the clearances are completely closed, . This sudden stiffening effect serves as a warning to the handler, preventing the interlocked hose from being over bent. This automatic warning feature makes the interlocked hose especially suitable for manual handling. The packing mechanism at the interlocked links does not offer a perfect seal. Therefore, the interlocked hose is satisfactory for carrying low-pressure air, steam, and water, but is generally not suitable for conveying gases and “searching” liquids such as kerosene and alcohol. The outside of the interlocked hose is relatively smooth, making it easy to handle without any covering. The inner cone with outer thread connector metal flexible hose assembly is normally not analysed. In most of the situations, the end displacements from piping or equipment connections are calculated from stress analysis software and those values are transferred to the vendor for their consideration. Accordingly, the hose length and installation space are determined. Pipe Supporting for optimum flexible hose working A piping system which utilizes fexible metal hose to absorb pipe movement must be properly anchored and guided to assure correct functioning and maximum service life of the metal hose assembly. The following basic principles should be observed: The direction of pipe motion must be perpendicular to the centerline (axis) of the hose. To prevent torsional stress, the pipe shall be anchored at each change of direction where a flexible metal hose is employed. Typical examples of correct and incorrect guiding are shown below in Fig. 5. Flexible Hoses are used to accommodate piping and equipment displacements. Hoses being extremely flexible, installations is very easy. However, a few general precautions should be exercised during installation to avoid hose failures. While installing flange connector metal flexible hose, the allowable minimum bend radius is the most fundamental limitation. For interlocked hoses, the limiting radius depends largely on the clearances between links. It has less to do with the stress and fatigue, so it generally has only one limiting radius for all applications. For corrugated hoses, on the other hand, the limiting radius depends on the stress at the corrugations. For pressure hoses with braided reinforcement, the corrugation stress comes mainly from the bending of the hose. Therefore, the corrugation stresses can be controlled by setting a limitation on the bending. In other words, the installation is acceptable if the hose is not bent beyond the limiting radius. Similar to the situation discussed in the bellow expansion joint, the mode of failure of the hose corrugation is due to fatigue. Therefore, the bend radius limitation depends also on the number of operating cycles expected. Most manufacturers provide two limiting radii, one for static application involving a one-time fit-up installation, and the other for operational movement involving many cycles of intermittent flexing. The whole design and installation process actually ensure that this minimum radius is maintained during the initial layout and throughout the operation. The article describes various types and sources of flexible metal hoses (FMH) vibration. Depending on the direction of vibration displacements, basic variations of sleeves vibration are identified: transversal, longitudinal and torsional. The distinguished forces, that excite vibration in FMH, acting on it, are divided into static and dynamic loads. The most common type of vibration - transverse vibration of flexible sleeves is considered in more details. Also, the ripples - one of the main causes of transverse vibration, which significantly degrade hydraulic performances of pipeline communications, are investigated. The paper presents the analysis of characteristics of the bending and longitudinal stiffness, which implies that the stiffness increases with increasing internal pressure, the diameter of the sleeve and the number of braids. To determine frequency characteristics of FMHs, the bar, with reduced parameters of elasticity and mass, has been chosen as FMH mathematical model. The research results of an influence of various factors on the metal sleeves eigenfrequencies have been studied. The first step in alloy selection is to determine the source of any potential corrosion. While corrosive attack may be initiated by the media running through the metal hose, it is also possible that corrosion can initiate from external sources. External corrosion If a hose assembly is used in a potentially corrosive environment, then it should be made using an alloy that is resistant to the corrosive agent unless it can somehow be shielded from exposure to that corrosive. This can be tricky, as many covers do not provide adequate corrosion protection, and may even exacerbate the problem. For example, there have been instances where flexible polyvinyl chloride (PVC) covers have been applied onto stainless steel-corrugated dock hoses as a means to protect them from the salt water environment. Over time, these covers can begin to degrade, releasing chloride-containing compounds that can attack the stainless steel hose. External corrosion can also be caused by media that drips or sprays onto the exterior surfaces of the connector. If the media being transferred through the hose or expansion joint is corrosive, then proper alloy selection is critical. Here, it is important to remember that although the product being conveyed may not be corrosive, it may contain impurities that can cause problems. A good example here would be steam transfer. Boiler water may contain various water treatment chemicals such as anti-scaling or anti-foaming agents, and water-softening chemicals, all of which can be corrosive if allowed to concentrate in the system. Natural gas may also contain sulfur-based impurities that can attack commercial stainless steels. This ‘sour gas’ can lead to critical safety issues if system corrosion results in gas leaks. A detailed analysis of the medium may be required in order to identify any corrosive impurities that may be present. Once potential corrosive agents have been identified, the next step is to determine which alloys will best withstand any corrosive attack. Most alloy producers provide detailed specification sheets for the alloys they offer that give valuable insight as to the suitability of a given alloy when exposed to certain chemicals. However, in corrosive applications, industry resources that show real-life test results might provide more reliable data. Various databases are published by organizations which perform corrosion testing on alloys, analyzing their resistance to different chemicals under various operating conditions. Some of these resources are referenced in industry standards and specifications. When using these databases, not only will you need to know the name of the chemical being transferred, but also the temperature and concentration percentage at which it is being conveyed, as these variables can have a dramatic effect on the corrosion rate. For example, sodium hydroxide is generally non-corrosive at low temperatures and concentrations, but becomes aggressively corrosive to stainless steel as the temperature and/ or concentration increases. This is also true for many water-treatment chemicals. Conversely, some chemicals may exhibit reduced corrosion at high concentrations, so caution is key. There are a few important considerations when consulting these corrosion resistance charts. First, they typically do not include any corrosion resistance data for name-brand chemicals or mixtures of multiple chemicals. If name-brand chemicals are being transferred, the chemical manufacturer should be consulted for corrosion resistance data. Secondly, certain corrosion resistance information may be product specific. In other words, corrosion charts that can be found in the back of catalogs for fittings, valves, pipe, etc. should not be used as a reliable corrosion guide for union connector metal flexible hose. While these charts are fine to use as a guide for the products in the catalog, they can be misleading. Although a chart may give an ‘acceptable’ rate of corrosion for those specified products, that same rate may not be acceptable for a flexible metal hose, which is formed using relatively thin-walled corrugated tubing. Incidentally, be wary of corrosion-resistance information found online and make sure that all data is published by a reliable source. Caveat emptor: Buyer beware, especially when the information is free. It is important to remember that, if a metal hose or expansion joint is attacked by a chemical, it is seldom because the alloy is defective. In most cases where corrosion is present, either the incorrect alloy was selected, or the alloy was exposed to unspecified chemicals to which it was not chemically resistant. “If the media being transferred through the hose or expansion joint is corrosive, then proper alloy selection is critical. Here, it is important to remember that although the product being conveyed may not be corrosive, it may contain impurities that can cause problems”
Publish Date: 22-10-21
Description: Printed Circuit Boards OrCAD PCB Editor is based on Allegro PCB Editor, so this book will be useful to new Allegro printed circuit boards Editor users as well. Allegro PCB Editor is a powerful, full-featured design tool. While OrCAD PCB Editor has inherited many of those features, including a common file format, it does not possess all of the capabilities available to the Allegro PCB tiers, such as Allegro High-Speed Option, Analog/RF Option, FPGA System Planner, Design Planning, and Miniaturization Option. Consequently most of the basic tools and features are described here, but only a few of the more-advanced tools are covered, as outlined later. PC board traces must be sized appropriately (both in width and thickness, or copper weight10) to carry the current that you need without excessive temperature rise. A rule of thumb is that a 10-mil-wide, 1-ounce PC board trace can carry in excess of 500 mA with a 20 °C temperature rise above ambient. PC board copper weight vs. trace thickness is shown in Table 15.5. An estimate of the current-carrying capability for 20 °C temperature rise of PC board traces is shown in Figure 15.12. The fusing current (Figure 15.13) for PC board traces is significantly higher. OK – So What’s a Printed Circuit Board? I’ve just mentioned a printed circuit board, but what exactly is a printed circuit board? Well, look inside any modern electronics appliance (television, computer, mobile phone, etc.) or even many electrical appliances (washing machine, iron, kettle, etc.) and you’ll see a printed circuit board – often known by the multilayer PCB. A printed circuit board is a thin baseboard (about 1.5 mm) of insulating material such as resin-bonded paper or fiberglass, with an even thinner layer of copper (about 0.2 mm) on one or both surfaces. (If copper is only on one surface it’s then known as single-sided printed circuit board; if copper is on both surfaces it’s known as double-sided printed circuit board.) The copper on the surface of a printed circuit board has been printed as a circuit (yes, OK, that’s why it’s called printed circuit board – geddit?), so that components on the printed circuit board can be soldered to the copper, and thus be connected to other components similarly soldered. Photo 12.1 shows a fairly modern printed circuit board to show you what they look like. The printed circuit board shown is quite a complex one, with hundreds of components – from a computer actually – but the printed circuit board in a washing machine, say, may only hold a handful of components. Photo 12.2 shows how the copper on a printed circuit board comprises a pattern of copper – sometimes called the copper track – rather than a solid layer. This pattern or track is the key to making connections between components. PCB design begins with an insulating base and adds metal tracks for electrical interconnect and the placement of suitable electronic components to define and create an electronic circuit that performs a required set of functions. The term printed isn’t exactly an accurate description of how the copper on the surface of a printed circuit board is formed. In fact, all printed circuit boards start life with a complete layer of copper on one or both sides of the insulating board. Then, unwanted copper is removed from the board, leaving the wanted copper pattern behind. Typically, this copper removal is usually – though not always – done by etching the copper away using strong chemicals. Figure 12.1 shows a cross-section of a simple printed circuit board. In it you can see the insulating board, the copper track, and the holes for component leads. Components fit to the printed circuit quite easily. Their leads are inserted through the board holes, and are then soldered to the copper track. Figure 12.2 shows how this works. In terms of the amateur enthusiast in electronics, simple (and relatively inexpensive) hand-tools are all that are required in this soldering process – we’ll look at these, and how to use them, later. Initially, a design specification (document) is written that identifies the required functionality of the thick copper PCB. From this, the designer creates the circuit design, which is entered into the PCB design tools. The design schematic is analyzed through simulation using a suitably defined test stimulus, and the operation of the design is verified. If the design does not meet the required specification, then either the design must be modified, or in extreme cases, the design specification must be changed. When the design schematic is complete, the PCB layout is created, taking into account layout directives (set by the particular design project) and the manufacturing process design rules. On successful completion of the layout, it undergoes analysis by (i) resimulating the schematic design to account for the track parasitic components (usually the parasitic capacitance is used), and (ii) using specially designed signal integrity tools to confirm that the circuit design on the PCB will function correctly. If not, the design layout, schematic, or specification will require modification. When all steps to layout have been completed, the design is ready for submission for manufacture. 1.2 EMC on the Printed Circuit Board Almost every printed circuit board (PCB) is different and completely application specific. Even within similar products the PCB can be different, for example open two PCs from different manufacturers, with the same processor, clock speed, keyboard interface, etc., the actual PCB layout will be different. This diversity means that every high tg PCB has a unique level of EMC performance, so what can possibly be done to ensure that this is within certain limits? It should not surprise circuit designers that the layout of the PCB can have a significant effect on the EMC performance of a system, usually more so than the actual choice of components. Consequently, PCB layout is one of the most critical areas of consideration for design to meet EMC regulations. The fact that there are so many different PCB designs in existence is a testimony to the low cost of producing a PCB, but relaying a complete PCB because of poor layout design causes significant increases in costs not present in the actual material price of the board. Relaying a PCB will create a delay in time to market, hence lost sales revenue. New PCB layouts or changes usually entail new solder masks, reprogramming component placement machines, rewriting the production instructions, etc., hence cost may not be present in the final product part cost, but in the development and production overhead. Although a significant factor in overall EMC performance, the recommendations for minimising the effect of PCB layout on EMC are general good PCB design practices. The cost of implementing these recommendations is solely in the time taken to ensure that these good design practices are implemented, vigilance and experience are the two main requirements, not necessarily new design software or extensive retraining. Printed circuit boards (PCBs) are by far the most common method of assembling modern electronic circuits. They comprise a sandwich of one or more insulating layers and one or more copper layers which contain the signal traces and the powers and grounds; the design of the layout of PCBs can be as demanding as the design of the electrical circuit. Most modern systems consist of multilayer boards of anywhere up to eight layers (or sometimes even more). Traditionally, components were mounted on the top layer in holes which extended through all layers. These are referred to as “through-hole” components. More recently, with the near universal adoption of surface mount components, you commonly find components mounted on both the top and the bottom layers. The design of the PCB can be as important as the circuit design to the overall performance of the final system. We shall discuss in this chapter the partitioning of the circuitry, the problem of interconnecting traces, parasitic components, grounding schemes, and decoupling. All of these are important in the success of a total design. PCB effects that are harmful to precision circuit performance include leakage resistances, IR voltage drops in trace foils, vias, and ground planes, the influence of stray capacitance, and dielectric absorption (DA). In addition, the tendency of PCBs to absorb atmospheric moisture (hygroscopicity) means that changes in humidity often cause the contributions of some parasitic effects to vary from day to day. In general, PCB effects can be divided into two broad categories—those that most noticeably affect the static or DC operation of the circuit, and those that most noticeably affect dynamic or AC circuit operation, especially at high frequencies. Another very broad area of high frequency PCB design is the topic of grounding. Grounding is a problem area in itself for all analog and mixed-signal designs, and it can be said that simply implementing a PCB-based circuit does not change the fact that proper techniques are required. Fortunately, certain principles of quality grounding, namely the use of ground planes, are intrinsic to the PCB environment. This factor is one of the more significant advantages to PCB-based analog designs, and appreciable discussion in this section is focused on this issue. Some other aspects of grounding that must be managed include the control of spurious ground and signal return voltages that can degrade performance. These voltages can be due to external signal coupling, common currents, or simply excessive IR drops in ground conductors. Proper conductor routing and sizing, as well as differential signal-handling and ground isolation techniques enable control of such parasitic voltages. One final area of grounding to be discussed is grounding appropriate for a mixed-signal, analog/digital environment. Indeed, the single issue of quality grounding can influence the entire layout philosophy of a high performance mixed-signal PCB design—as it well should. Function of OrCAD PCB Editor in the printed circuit board design process PCB Editor is used to design the PCB by generating a digital description of the board layers for photoplotters and CNC machines, which are used to manufacture the boards. Separate layers are used for routing copper traces on the top, bottom, and all inner layers; drill hole sizes and locations; soldermasks; silk screens; solder paste; part placement; and board dimensions. These layers are not all portrayed identically in PCB Editor. Some of the layers are shown from a positive perspective, meaning what you see with the software is what is placed onto the board, while other layers are shown from a negative perspective, meaning what you see with the software is what is removed from the board. The layers represented in the positive view are the board outline, routed copper, silk screens, solder paste, and assembly information. The layers represented in the negative view are drill holes and soldermasks. Copper plane layers are handled in a special way, as described next. Fig. 1.17 shows routed layers (top and bottom and an inner, for example) that PCB Editor shows in the positive perspective. The background is black and the traces and pads on each layer are a different color to make it easier to keep track of visually. The drill holes are not shown because, as mentioned already, the drilling process is a distinct step performed at a specific time during the manufacturing process. PCBs usually contain epoxy resin, fiberglass, copper, nickel, iron, aluminum and a certain amount of precious metals such as gold and silver; those materials and metals along with electronic parts are attached to the board by a solder containing lead and tin. The main material composition of PCBs was determined and is shown in Table 13.1. From the table, the composition of metals, ceramic and plastics could reach 40%, 30% and 30%, respectively. Further, the concentrations of precious metals in waste PCBs are richer than in natural ores, which makes their recycling important from both economic and environmental perspectives. Table 13.2 shows the average content and value ratio of different metals in PCBs. One can see that Au, Cu, Pd and Ag account for nearly all of the economic material value in waste PCBs. Therefore, PCB recycling focuses on recovering these metals above all else. For the technology and engineering of very complex boards, the United States, the United Kingdom, Germany and France still have a competitive advantage. There is every reason to believe that the advantage will soon be lost to Asia. Asia produces three-fourths of the world’s PCBs, with over 1000 manufacturers in China alone. The PCB industry, like the larger electronics industry, has always had a global component. Only in the past four years, however, has the US manufacturing base faced a serious decline. In 2003, the United States produced 15% of the world’s PCBs, trailing Japan, the largest producer at 29%, and China, the second largest at 17%. Taiwan was the fourth largest producer at 13%. Europe produced only 10%, and South Korea 8%. No American company is now among the top ten manufacturers of PCBs. China has overtaken Japan as the leader in PCB production and is forecast to produce $10.6 billion worth of PCBs, accounting for 25% of the world total (LaDou, 2006).
Publish Date: 21-10-21
Description: Are magnetic eyelashes worth the hype? False lashes can leave you in a sticky situation ... literally! If you find yourself ripping out your own lashes or tugging at leftover goo two days later, then allow me to introduce you to the concept of magnetic lashes. What makes magnetic lashes so appealing is that they're reusable, they don't require messy glue and they're less likely to rip off your natural lashes. Basically, they seem like a cool, low-maintenance version of the original, glue-on version. While there are some luxe varieties on the market (around $70), Ardell just launched a drugstore version that's a lot more affordable (at $11). Instead of two magnets (like the first-generation versions), Ardell touts that these have anywhere from three to eight smaller, virtually invisible magnets embedded end to end so it will lay down seamlessly on the lashline and won’t bulge out in the middle. The company launched both full strips as well as accents, which are placed on the outer corners of the eyes. At TODAY Style, we had to give them all a try! The brand recommends applying a layer of mascara prior to application. This gives the lashes some grip and also helps natural lashes blend in. Lashes are marked as upper and lower in each package. I don't know exactly what would happen if you mixed them up (the thought gives me shivers), so let's assume we'll all delicately and mindfully place them back in their proper home after every use. It seemed simple enough: With the top strip, you line up the outside of the lash with the outer edge of your lashline. Next, you bring the bottom lashes to meet the top and when they are close enough — click — the magnets snap together and you're golden. I won't lie, there’s definitely a learning curve. That top lash will inevitably fall on the ground, the bottom one won't snap into place, but after a few attempts, I started to get the hang of positioning both. The most satisfying part is hearing it actually click into place. Success! If you do need to realign or start over, just grab the magnets at the base of your lashline and roll your thumb and index finger in opposite directions to unlock them. Then, gently slide them off your lashes. Things seemed to be going well until ... well, until I looked in the mirror. Yikes. They are a bit too bold for me! The lashes didn't blend well with my own and I could distinctly see the magnet on the underside of the lash. If I blinked slowly enough I could feel the cold magnet on my eyeball. It's a feeling that's tough to describe, but certainly not ideal. IF YOU CONSIDER a quick swipe of mascara sufficient lash enhancement, this news may confound you, but among a growing segment of America’s female population, false lashes are a daily staple. Touted by influencers like “Shahs of Sunset” star and Lilly Lashes founder Lilly Ghalichi, fake fringes are no longer fringe, with U.S. sales reaching nearly $270 million in 2018, up 31% from 2017, according to polling firm Nielsen. Fans of fake lashes value their exaggerated, eye-opening drama, but, with their messy, irritating glue, applying them has always been a pain. The even bigger news for lash lovers: Reusable magnetic fake lashes—which attach via a thin strip of magnets at the base instead of glue—have recently come on the scene. Intriguingly, I received a kit as a gift, but after one frustrating session trying to master the tweezer-like applicator, I understood why “how to apply magnetic lashes” was Google’s top trending beauty search in 2018. The struggle to get them on has spawned a subgenre of YouTube videos offering either clever hacks or brokenhearted reviews. These polarized (and polarizing) temporary lashes consist of a set of two lash strips studded with tiny magnets that adhere to each other, sandwiching the wearer’s own upper lashes. They’re typically made of synthetic or human hair, and for a luxe option Uptown Lashes sells a mink set ($30, uptownlashes.com). Some kits, such as the one from One Two Cosmetics, are sold with a tweezer-like applicator included ($69, onetwocosmetics.com). Ardell’s popular lashes are more of a deal starting at $14 a kit, with an applicator sold separately for $4 (ardellshop.com). Some women use tweezers or their fingers to apply the lashes. Though simple in concept, the process is difficult in practice due to the magnets’ minute size and the exacting placement required. New York-based makeup artist Mary Irwin said that a magnifying mirror could help, and recommends looking down into the mirror so you can see the underside of the lash. Then, dexterous users can “gently drop the top part of the magnetic lash above the natural lash,” which is the step that requires extensive practice. However, Ms. Irwin conceded that “for everyday wear, I don’t think they’re the most practical.” Having studied online tutorials carefully and still failed to apply my own set, I would have to agree. The boom of eyelash growth serums, lash extension and curling procedures, and lengthening mascaras should prove the point—the world is obsessed with the quest to longer, fuller eyelashes. But despite all this new beauty tech, applying false eyelashes is one tried-and-true trick that makeup artists and celebrities have been using for years. And the surge of magnetic eyelashes hitting the market proves this option isn't one to ignore. Once only adhered to your natural lash with adhesive glue, mink magnetic eyelashes secure to each other, and your lash line, with tiny magnets. The latest brand to launch this type of technology is celebrated falsies brand, Ardell. According to Jadene Munson, the Global Brand Ambassador, they "feature virtually invisible magnets placed along the lash line that lock together and secure the lash along your natural lash line." This brand's full strip lashes, specifically, feature four magnets for an impressive hold, while the accent lashes feature three magnets. Basically, you are sandwiching your natural eyelashes between two strips held together with magnetic force. It's relatively simple. Each product will differ slightly, so it's best to follow the instructions on the package. First, it's often recommended to trim the lash so it'll naturally fit along your natural lash line. Then, Munson recommends applying mascara to give your eyelashes more grip. For Ardell's strip eyelashes, the next step is to lay the Upper Magnetic Lash across the top of your lash line. Then, you place the Under Magnetic Lash from the tray and place it underneath your natural lash line. Thanks to the magnets, they will lock in place. Another popular brand is One Two Cosmetics, seen above. These magnetic lashes come in full strips or half lashes to accent the outer corners. This brand's magnetic lashes also come with an applicator that looks a little like tweezers, but you can apply them with your fingers, too. The same logic applies—the upper lash is magnetically attracted to the bottom—but you can watch this short video for a visual breakdown. To remove the Ardell lashes, Munson says to gently pull them apart by lifting the top lash up and pulling the bottom one down. You can also slide the top and bottom magnets away from each other "one by one." However, you should never pull them straight off, as this could harm your natural lashes. One Two recommends using your thumb and index finger to slide them apart. RELATED: The 10 Best Eyelash Growth Serums on the Market The Best Faux Mink Magnetic Eyelashes The two brands that are creating the most buzz are One Two ($59; hsn.com) and Ardell ($8; walmart.com), both of which are reusable. When deciding between the two, consider the price-tag, and also the material used. And if you have sensitivities or allergies, this is extremely important. Ardell's are made with 100 percent human hair, while One Two's are synthetic. We should note that while they're easier to use than traditional glue-on lashes, there is still a slight learning curve. Make sure to give yourself a few test-runs before applying them for an important event. As far as options go, both of these brands offer different styles to choose from, whether it's a bold and glamorous look you're attempting to recreate, or something more subtle and natural. In the world of eyelashes, there’s always a new product or two floating around that claims to be better at giving you the longer, fuller lashes you’ve wanted. We’ve been searching for ways to enhance our eyes for centuries. Nothing frames your eyes and makes them more noticeable than a great set of soft, voluminous lashes, and we would do practically anything to get them. One of the newer beauty trends to hit the eyelash scene are magnetic eyelash strips. We admit, our curiosity was piqued when we first heard of these. How can magnets help you get longer, fuller lashes? Is it safe? Affordable? You know we’re your eyelash info insiders, so we got the scoop on magnetic lashes so you don’t have to waste your time researching them for yourself. Serums, salon treatments, and miracle lash conditions may have all made a name for themselves in the realm of lash enhancement, but the tried-and-true method of eyelash lengthening and thickening has always been the use of falsies. This is the go-to method of eye enhancement for everyone from celebrities to the coworker sitting in the cubicle next to you. Eyelash strips are the industry standard for many reasons. They’re safe. Serums with certain formulas and salon extensions come with some pretty risky side effects. Skin and iris discoloration, natural eyelash loss, and eye infection are all safety concerns for these methods of enhancement. Eyelash strips are generally well tolerated by everyone and are safe to apply and remove on a daily basis. They’re affordable. Other methods of magnetic false eyelashes enhancement can be extremely expensive. A full set of professionally applied eyelash extensions alone can be upwards of $300, and that doesn’t factor in the cost for maintenance and upkeep. Serums are not much cheaper, considering that they often cost over $100 and usually last about thirty days. Once you stop using a serum, any lash lengthening effects disappear, so if you want to continue the effect a serum can potentially offer, you’ll need to continue using it. Eyelash strips cost a fraction of the price and are reusable twelve to fifteen times. Doe Lashes cost just under $13 per pair, which means you can have glamorous lashes all month for less than it costs you to go grab brunch with your friends. They’re instant. Other lash enhancement options may take time to provide results. Eyelash serums can take up to three to four weeks before taking effect, and that growth isn’t as noticeable or remarkable as a set of false lashes. Eyelash extensions can give you instant length and volume...after a few hours in the salon chair. Get comfortable in the chair, because you’ll be headed back to the salon for “fills” every few weeks. Eyelash strips can be easily applied and removed within minutes, without any in-between or continued maintenance required. They’re DIY. You can apply false eyelash strips at home without any prior experience and get professional looking, gorgeous results right in your own bathroom or bedroom, no tipping required. Since false eyelash strips are the industry standard for eyelash enhancement, it’s no surprise companies are continually trying to change or repackage the design. Magnetic lashes are different from strip lashes in how they attach to your lash line. Traditionally, eyelash strips attach just above your natural lash line with glue or a holding gel. Glue is the most traditional method of adhering false magnetic eyelash accessories to your lids, and a great quality glue can hold your lashes in place for hours on end. Depending on the brand, they can even endure things like sweat and water. Just like some companies sell eyeliner kits, you can also get lash kits for convenience. Magnetic lashes are held in place by complete magnetic contact. Think of it as using basically invisible magnets (or smaller magnets that are compact). You will have lashes with bottom magnets and an upper magnetic lash as well. To apply magnetic lashes, you will need to invest in not only specially made eyelash strips that have tiny magnets attached to the lash band, but also a specialty iron-oxide magnetic liner. Magnetic lashes are applied by first applying a thin strip of liquid iron-oxide eyeliner on top of your natural lash line, waiting for it to dry, and then clipping the magnetic lash strip to the eyeliner using an applicator tool. Some people like to put all their items on a small tray so they don't lose anything during the application process. To remove magnetic lashes, you’ll need to pull the magnetic lash bands off, and then remove the liner. Try using your index finger and thumb for a solid grip. Some companies suggest using olive oil to remove the eyeliner, while other manufacturers carry a specialized iron oxide eyeliner removing solution. It isn’t recommended you use regular eye makeup remover, as it may not be effective in removing the liner and can be damaging to the lash band if it is exposed to a remover containing oil.
Publish Date: 21-10-21
Description: Structural behavior of precast concrete wall panels due to dynamic load: A review The rapid population growth and urbanization have made a massive demand for the shelter and construction materials. Masonry walls are the major component in the housing sector and it has brittle characteristics and exhibit poor performance against the uncertain loads. Further, the structure requires heavier sections for carrying the dead weight of masonry walls. The present investigations are carried out to develop a simple, lightweight and cost effective technology for replacing the existing wall systems. The lightweight concrete is developed for the construction of cement wall panel. The EPS (Expanded Polystyrene) beads of 3 mm diameter size are mixed with concrete and developed a lightweight concrete with a density 9 kN/m3. The lightweight sandwich panel is cast with a lightweight concrete inner core and ferrocement outer skins. This lightweight wall panel is tested for in-plane compression loading. A nonlinear finite element analysis with damaged plasticity model is carried out with both material and geometrical nonlinearities. The experimental and analytical results were compared. The finite element study predicted the ultimate load carrying capacity of the sandwich panel with reasonable accuracy. The present study showed that the lightweight concrete is well suitable for the lightweight sandwich wall panels. Architectural precast concrete wall panels that act as loadbearing elements in a building are both a structurally efficient and economical means o f transferring floor and roof loads through the structure and into the foundation. In many cases, this integration can also simplify construction and reduce costs. This article presents the many benefit s that ca n be derived from using loadbearing architectural precast concrete walls in buildings. Discussed herein are the various shapes and sizes of wall pane ls, major design considerations, and when loadbearing or shear wall units should be the first design choice. The role o f connections, shear walls, and the use of precast concrete as forms for cast-in-place concrete is explained. In general, the design methods and techniques presented in this article apply to buildings in both seismic and non-seismic areas. The latter part of this article shows how these design principles can be applied in practice in a variety of buildings. These examples illustrate the use of window wall panels, spandrels, and solid or sandwich wall panels as the loadbearing wall members. When all the advantages of using architectural precast concrete as loadbearing walls are added up, it makes good sense to use this structural form in building applications. An experimental study has been carried out to determine the strength and behaviour of bamboo-reinforced concrete wood texture cement wall panel under one-way in-plane action. Three full-scale bamboo-reinforced concrete wall panels were tested to fail under a uniformly distributed load applied at an eccentricity of t/6. Slenderness ratio of all wall panels was kept constant as 25 with varying aspect ratio and thinness ratio. The influence of aspect ratio and thinness ratio on the ultimate strength and behaviour of wall panel was studied. The aspect ratio of wall panels considered includes 1, 1.204 and 1.515, and thinness ratio of wall panels includes 16.5, 20.75 and 25. Based on the study, an empirical equation for predicting the ultimate load of bamboo-reinforced concrete wall panel was proposed. The effect of the earthquake resulted in the destruction of infrastructure, especially residential buildings. The construction of decent housing with an adequate level of security is a demand. Generally, the most severe damage when an earthquake occurs is wall collapse of the houses. The precast panel wall is an alternative solution in answering the needs of post-earthquake housing development, because of the fast construction time and high calculation accuracy. The behavior of structural precast concrete split rock surface wall panels designed improperly instead of following the standard or regulations will likely encounter a poor performance during an earthquake compared to those designed in accordance with the standards. The purpose of the present study is to compile the findings from previous studies of precast concrete panel walls, especially their performances in handling earthquake load. It reveals that the stability, especially in ductility, affects the performance of precast concrete panel walls. In this study, the walls of precast concrete panels are made in half scale and given dynamic loads to simulate earthquake forces. This review is expected to provide guideline of similar subsequent research. It’s no wonder demand for precast is rising, especially considering the numerous benefits structural precast panels offer — from quick installation to fire resistance. 1. Thermal insulation All elements of a well-engineered structural precast panel work together to provide a high level of insulation. Manufacturers often use a combination of concrete and EPS foam that maximizes the foam in the concrete piece, increasing insulation capabilities. A building constructed of structural precast panels may reduce energy consumption by as much as 30%. 2. Sustainable materials Quite simply, a building made with structural precast panels will consume less energy, but an idea that should be at the heart of any sustainability conversation is product life. The use of concrete dates back to Roman times and its durability is still on display all across Europe. That raw, ancient building material has remained virtually unchanged for thousands of years. Many of the materials used in precast concrete are, as a rule, locally sourced, including the cement, the coarse and fine aggregates, and the steel. 3. Long-term viability and flexibility Structural precast allows for a very modular building envelope. As business requirements change and needs evolve, an existing precast building has the flexibility to be expanded and modified. With structural precast concrete panels, you can add or remove pedestrian doors and dock doors, incorporate daylighting options, and even remove 75% of a wall. And due to its modular design, total repurposing of a precast building is entirely possible; churches can become car dealerships, warehouses can become micro-breweries… the options are only limited by a property owner’s imagination. 4. Quick installation Speed is a critical hallmark of structural precast construction. “With precast panels, you can establish a larger completed footprint in a shorter amount of time,” says George Miks, director of engineering.“If you think of a masonry wall, what they send out to the site are a bunch of blocks that have to be assembled and constructed out in the field.” When structural precast panels arrive at a job site, the pieces are ready to install. If things go smoothly out in the field, an experienced crew can install 20 to 30, 12-foot panels in a day. 5. Load-bearing capabilities and wind resistance Structural precast concrete panels are comprised of high-strength concrete and prestressed steel strand. It’s relatively routine for precast concrete wall panels have a compressive strength of approximately 7,000 PSI. You can apply loads in excess of 100,000 pounds to the panels, Miks says. “When you build steel buildings, for instance, you have to put up perimeter beams and columns and then put steel skin against it. All of that steel has to support those enclosure panels,” Miks says. “With a structural precast wall system, you don’t need any of those perimeter beams and columns. You can just tip up the panel and have the roof steel members themselves attach to the precast. That also means you’ll be spending less on steel.” Precast also stands up to Mother Nature’s wrath, shrugging off tornadoes, flying projectiles and winds up to 250 miles per hour. 6. Fire and sound ratings Concrete is obviously an effective barrier for fire; it simply doesn’t burn well. Precast concrete thin cement rammed earth wall panels are capable of providing a two- to four-hour fire rating. Precast walls also stay intact even in hot chemical fires. Warehouses often use precast wall panels as dividers to protect goods on the other side of fire-prone areas. “The more delay you can create from one side to the other, the better chance of getting people out safely without incident and also the higher probability of protecting goods and services,” Miks says. Constructing a commercial structure is a huge undertaking and a significant investment. Whether you’re charged with the growth of a company, serving your community or building a legacy of your own, precast construction is a solid, responsible option said Miks. In this paper, an optimization-based design model of precast concrete cement rustic decoration wall panels for a building facade is presented. The key concept is an integrated model that can concurrently handle all of the related design and construction disciplines in the decision making process. The integrated model is decomposed hierarchically into several subproblems, thus a multilevel multiobjective optimization problem is obtained. Besides the multilevel aspect, the model presented can also handle knowledge-based requirements which are in general difficult to deal with by conventional hill-climbing optimization schemes. A solution procedure to solve this model is developed and applied to an example of PCWP for a four-story building facade.
Publish Date: 21-10-21
Description: Fastener Help Articles You may have heard of "Blue Bolt Coating", its real name is Whitford Xylan? Coating... and it isn't always blue. Many of our customers ask for the "Blue Bolt Coating", but what exactly is Xylan and when should it be used? Xylan is a blend of fluoropolymers, engineering plastics and selected corrosion inhibitors which, when combined, create these characteristics in fasteners: Low friction Exceptional adhesion Unusual resistance to wear and abrasion Excellent corrosion resistance Resistance to chipping Resistance to the weather, sunlight and salt water Xylan's versatility is best demonstrated as a coating for stud Bolts and nuts, where it provides unparalleled performance in ease of installation, corrosion resistance and ease of removal. It can be used on standard alloy steel nuts and bolts, or can be paired with stainless steel fasteners for even more benefits. Xylan fastener coatings or "Blue Bolt Coatings" are typically specified in oil and waterworks applications. A bolt’s function essentially boils down to applying a high enough Hose Clamps force that when external forces are applied, transverse movement and separation cannot occur. Using calibrated torque tools to tighten fasteners and apply that clamp force is far superior to going by the user’s judgement or feeling. Or, as one senior technician calls it “The One Grunt or Two Grunts Method”. Measuring torque alone, however, does not ensure a proper installation. 1. Torque is an indirect indicator of Tension. Torque is the measurement of twisting force needed to thread the fasteners together. 2. Tension is the force that actually holds an assembly together. Put another way: A bolt can stretch similar to a spring, as it becomes tightened once all the parts of the assembly are brought together. The higher the torque applied to the fastener, the more tension is created as the bolt stretches. If a bolt is like a spring and more torque equals more tension, why does not a certain amount of torque always result in the same amount of tension? Though the relationship between torque and tension is linear, many other factors can affect this relationship. Some of these factors include surface texture, rust, oil, debris, material type, locking elements and human error. Because of these variables, tightening to a specific torque setting can create varied results in the field or on the assembly line. General commodity commercial fasteners do not fall under the umbrella of products that would require a UL listing or ICC-ES report. There are three main governing bodies that cover specifications for fasteners. ASTM (American Society for Testing and Materials) covers primarily bolts and fasteners for construction applications. SAE (Society of Automotive Engineers) covers fasteners for automotive, machinery, and OEM applications. ASME (American Society of Mechanical Engineers) standards B18.2.1 and B18.2.1 cover dimensional tolerances for square and hex head bolts, Screws, and Nuts. Mudge Fasteners provides fasteners to these three sets of specifications (ASTM, SAE, and ASME). A fourth specification group that is also applicable is AASHTO (American Association of State Highway & Transportation Officials). AASHTO specifications are typically only called out on highway projects and many AASHTO designations can be directly converted to an ASTM equivalent. ICC (International Code Council) is the primary governing body responsible for writing and maintaining building, plumbing, mechanical, and fire codes adopted by local and state municipalities, and the federal government. ICC-ES (International Code Council-Evaluation Services, Inc.) is the branch of ICC responsible for performing technical evaluations of building products, components, methods, and materials to ensure that they meet the requirements of the codes. This evaluation process culminates in an ICC-ES report that provides evidence that the evaluated product or system meets code requirements. However, in the case of most anchor bolts and fasteners, the applicable sections of the codes (International Building Code, International Residential Code, International Property Maintenance Code, Etc.) direct you to the ASTM specifications covering said Anchors or fasteners. As the ASTM specifications already cover anchor bolts and fasteners in detail, there is no reason for ICC to write their own specifications for these items. For the same reason, ICC-ES does not need to perform evaluation testing of anchor bolts or fasteners. As long as the bolts meet the applicable ASTM specification(s), they will meet the applicable Code section(s). When you are shortening bolt or Threaded Rods with a hacksaw, you always mangle the threads at the sawn end, making it difficult to get a nut threaded onto it. Reader Larry LeMasters tip produces a much better ending. Thread two nuts onto the bolt at the cutoff spot, tighten them against each other, then saw against the shoulder to create a clean right-angled cut. Next, loosen the nuts and file a slight bevel around the end to clear burrs created by sawing. Then spin off the nuts to clean and realign the threads. Your shorter bolt will work just like a new one from the box. There are several distinct types of fastener, which may be referred to as a pin. These include small headless nails, sharpened pins used for holding fabrics while sewing, attaching paper to pinboards and the like, and several types of mechanical fasteners. Pins are an unthreaded mechanical fasteners, which are designed to be inserted through preformed holes. Lock Washers and vibration-resistant washers are designed to prevent a threaded fastener from loosening. The terms are often used interchangeably. However, there is a difference. Lock washers resist torque or loosening for a given preload, and vibration-resistant washers maintain a more constant preload when there’s movement in a joint. A lock washer may include some teeth to increase friction or tabs to provide positive locking. A vibration-resistant washer, on the other hand, will be sprung so that as the joint moves, a relatively consistent preload is maintained on the fastener. Rivets are mechanical fasteners with a plain unthreaded shaft that are inserted through holes to join two or more parts together. A permanently formed head at each end prevents the rivet from removal from the hole. The shaft prevents any radial movements of the components. Depending on the type of rivet, and its ability to support shear load, it can resist considerable forces. The heads prevent axial movements of the parts, although less force is supported in this way.
Publish Date: 20-10-21