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- Создано: 03-11-22
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Silicon Carbide (SiC): The Future of Power?
Описание: Silicon Carbide (SiC): The Future of Power? Silicon carbide, also known as SiC, is a semiconductor base material that consists of pure silicon and pure carbon. You can dope SiC with nitrogen or phosphorus to form an n-type semiconductor or dope it with beryllium, boron, aluminum, or gallium to form a p-type semiconductor. While many varieties and purities of silicon carbide exist, semiconductor-grade quality silicon carbide has only surfaced for utilization in the last few decades. How to Create Silicon Carbide The simplest silicon carbide manufacturing method involves melting silica sand and carbon, such as coal, at high temperatures―up to 2500 degrees Celsius. Darker, more common versions of silicon carbide often include iron and carbon impurities, but pure SiC crystals are colorless and form when silicon carbide sublimes at 2700 degrees Celsius. Once heated, these crystals deposit onto graphite at a cooler temperature in a process known as the Lely method. - Lely method: During this process, a granite crucible heats to a very high temperature, usually by way of induction, to sublimate silicon carbide powder. A graphite product rod with lower temperature suspends in the gaseous mixture, which inherently allows the pure silicon carbide to deposit and form crystals. - Chemical vapor deposition: Alternatively, manufacturers grow cubic SiC using chemical vapor deposition, which is commonly used in carbon-based synthesis processes and used in the semiconductor industry. In this method, a specialized chemical blend of gases enters a vacuum environment and combines before depositing onto a substrate. Both methods of silicon carbide wafer production require vast amounts of energy, equipment, and knowledge to be successful. How is Silicon Carbide Useful? Historically, manufacturers use silicon carbide in high-temperature settings for devices such as bearings, heating machinery components, car brakes, and even knife sharpening tools. In electronics and semiconductor applications, SiC's advantage main advantages are: - High thermal conductivity of 120-270 W/mK - Low coefficient of thermal expansion of 4.0x10^-6/°C - High maximum current density These three characteristics combined give SiC excellent electrical conductivity, especially when compared to silicon, SiC's more popular cousin. SiC's material characteristics make it highly advantageous for high power applications where high current, high temperatures, and high thermal conductivity are required. In recent years, SiC has become a key player in the semiconductor industry, powering MOSFETs, Schottky diodes, and power modules for use in high-power, high-efficiency applications. While more expensive than silicon MOSFETs, which are typically limited to breakdown voltages at 900V, SiC allows for voltage thresholds at nearly 10kV. SiC also has very low switching losses and can support high operating frequencies, which allows it to achieve currently unbeatable efficiencies, especially in applications that operate at over 600 volts. With proper implementation, SiC devices can reduce converter and inverter system losses by nearly 50%, size by 300%, and overall system cost by 20%. This reduction in overall system size lends SiC the ability to be extremely useful in weight and space-sensitive applications. Silicon Carbide Applications Many manufacturers are charging forward in using SiC in applications such as electric vehicles, solar energy systems, and data centers. These efficiency-oriented systems all result in high voltages and high temperatures. We're seeing a significant global push to implement SiC over other materials in an effort to reduce carbon emissions caused by power inefficiencies at higher voltages. Although cutting-edge technologies such as electric vehicles and solar energy are pioneering the utilization of SiC, we expect to see more legacy industries follow suit soon. SiC has become popular in the automotive sector as a result of the industry's demand for high quality, reliability, and efficiency. SiC can answer high voltage demands with prowess. Silicon carbide has the potential to increase electric vehicle driving distances by increasing the overall system efficiency, especially within the inverter system, which increases the vehicle's overall energy conservation while reducing the size and resultant weight of battery management systems. Goldman Sachs even predicts that utilizing silicon carbide in electric vehicles can reduce EV manufacturing cost and cost of ownership by nearly $2,000 per vehicle. SiC also optimizes EV fast-charging processes, which typically operate in the kV range, where it can reduce overall system loss by almost 30%, increase power density by 30%, and reduce the component count by 30%. This efficiency will allow fast charging stations to be smaller, faster, and more cost effective. In the solar industry, SiC-enabled inverter optimization also plays a large role in efficiency and cost savings. Utilizing silicon carbide in solar inverters increases the system's switching frequency by two to three times that of standard silicon. This switching frequency increase allows for a reduction in the circuit's magnetics, resulting in considerable space and cost savings. As a result, silicon carbide-based inverter designs can be nearly half the size and weight than that of a silicon-based inverter. Another factor that encourages solar manufacturers and engineers to use SiC over other materials, such as gallium nitride, is its robust durability and reliability. Silicon carbide's reliability enables solar systems to achieve the stable longevity they need to operate continuously for over a decade. Saving the World with Silicon Carbide Several key leaders in the silicon carbide space are providing bountiful resources and products centered around SiC. Cree Wolfspeed offers a variety of silicon carbide products, such as: - MOSFETs - Diodes - AEC-Q101 (automotive) rated MOSFETs -Bare die solutions Cree Wolfspeed is also the largest manufacturer of base SiC wafers, making them an expert in all things SiC. Cree is dedicated to expanding silicon carbide's feasibility and adoption by 2024. To learn more, check out their full offering of silicon carbide solutions. Silicon Labs offers excellent isolation solutions specifically aimed at supporting silicon carbide-based designs in the electronic vehicle market. Their target solutions range from battery management systems to traction control inverters that rely on high-frequency power distribution. For more information on Silicon Labs solutions, you may want to learn about how they are revolutionizing EV power. Other semiconductor companies, such as Rohm Semiconductor, boast large portfolios of silicon carbide products as well, including power MOSFETs and power modules.
Дата Публикации: 03-11-22
What Procedures Are Done in a Cath Lab?
Описание: What Procedures Are Done in a Cath Lab? Most X-ray devices are used for medical diagnosis, but for certain procedures the units can be both diagnostic and interventional. Among these belong mobile C-arms and cath lab system. We have written about the use of mobile C-arm machines, but what procedures are done in a cath lab, and when would you use a cath lab rather than a mobile C-arm? Let us take a look. What is a Cath Lab? Cath lab, short for catheterization laboratory, is an examination room in a hospital or clinic with diagnostic imaging equipment. It is similar to a C-arm system except that it is not mobile but a mounted system with a table. It also has more power than a mobile C-arm. In a cath lab, physicians perform minimally invasive tests and procedures to diagnose and treat, for example, cardiovascular diseases. The procedures performed in a cath lab often include small, flexible tubes, called catheters that are used instead of open surgery, to access the heart and blood vessels. In general, cath labs consist of: Patient table Image intensifier / Flat panel detector Viewing monitors Injector pump Angioplasty balloons Defibrillator Most cath labs have a single X-ray generator source and X-ray image intensifier for fluoroscopic imaging. Those are single plane cath labs, either floor or ceiling mounted. Older cath labs use cine film to record the information (these are analog cath labs). However, since the early 2000's, most new facilities have gone digital. In the market, there are also biplane or dual plane cath labs. Dual cath labs have two C-arms, where either both are ceiling mounted or one is ceiling and the other is floor mounted. This means that the system has a dual X-ray source as well as a dual detector that allow simultaneous two plane visualization in, for example, coronary procedures. Most top providers of medical robot imaging equipment also manufacture cath labs. You can find cath labs from GE, Philips, Siemens as well as Canon Medical (former Toshiba). What Procedures Are Done in a Cath Lab? Typically, you would use a cath lab for: Cardiac procedures Vascular procedures Angiography procedures Neurology procedures The different types of interventional work require different characteristics of the cath lab with opration table. Nevertheless, the most important determinants to help you decide which cath lab fits your needs are: Whether the system is single plane or biplane Floor or ceiling mounted And the size of the detector Let us discuss these in more detail. Biplane systems can acquire 3D images faster because they capture image data from detectors on two axes instead of just one. Even though single plane cath labs (picture on the left) are also capable of 3D imaging, it takes longer for the C-arm to move. And thus, the software's reconstruction process can cause delays. Moreover, biplane cath labs come with the 3D software as a standard, while it must be added to the single-plane systems. Another difference is in the site preparation. A biplane cath lab is basically a double C-arm, therefore, you need more space as well as more time to have the site ready for your cath lab. Biplane systems can acquire 3D images faster because they capture image data from detectors on two axes instead of just one. Even though single plane cath labs (picture on the left) are also capable of 3D imaging, it takes longer for the C-arm to move. And thus, the software's reconstruction process can cause delays. Moreover, biplane cath labs come with the 3D software as a standard, while it must be added to the single-plane systems. Another difference is in the site preparation. A biplane cath lab is basically a double C-arm, therefore, you need more space as well as more time to have the site ready for your cath lab.
Дата Публикации: 03-11-22
Canned Mushrooms: Are There Health Benefits
Описание: Canned Mushrooms: Are There Health Benefits Mushrooms are the reproductive structures produced by some fungi. A mushroom, or toadstool, is the fleshy, spore-bearing, fruiting body of a fungus. In a way, mushrooms are like the fruit of a plant. Instead of producing seeds, the mushroom fungus releases millions of microscopic spores that form underneath the mushroom's cap. Mushrooms grow in a variety of bright and muted colors all over the world. The fungus can grow above ground, on top of the soil, or on the surface of a food source. They are easy to grow at home as well. There are more than a million estimated species of fungi. Species that make edible mushrooms make up only a small fraction. Producers make canned mushrooms by slicing fresh mushrooms and packing the pieces in brine. Next, they seal the cans and send them through a pressure canning process. Canned mushrooms are small, but mighty when it comes to health benefits. They are a rich source of several vitamins and minerals. Nutrition Information A half-cup of canned, drained, mushroom in brine pieces contains: 20 calories 1 gram of protein 0 grams of fat 4 grams of carbohydrates 2 grams of fiber 2 grams of sugar Canned mushrooms are a viable "meat replacer" thanks to their protein content and fleshy texture. Canned mushroom in SO2 are also an excellent source of: Riboflavin Niacin Potassium Phosphorus Copper Pantothenic Acid Selenium Potential Health Benefits of Canned Mushroom in vinegar Canned mushrooms have the same nutritional content as fresh mushrooms. However, the added sodium from the canning brine (saltwater) is something to consider if you are trying to limit how much sodium you have. The phosphorus in canned mushrooms helps red cells deliver oxygen and may give you more energy. Help give you stronger bones and healthier teeth. Although bone health is primarily related to calcium, minerals such as phosphorus are also important to supporting healthy bones. Mushrooms contain a fair amount of phosphorus to promote greater bone and teeth health. Improve your digestion. The fiber in canned mushrooms contributes to a healthy digestive system. The body needs fiber to bulk up stool so it can pass more easily through your digestive tract. Adding fiber to your diet also helps if your stool is thin or watery.
Дата Публикации: 03-11-22
Internal Combustion Engine Basics
Описание: Internal Combustion Engine Basics Internal combustion engines provide outstanding drivability and durability, with more than 250 million highway transportation vehicles in the United States relying on them. Along with gasoline or diesel, they can also utilize renewable or alternative fuels (e.g., natural gas, propane, biodiesel, or ethanol). They can also be combined with hybrid electric powertrains to increase fuel economy or plug-in hybrid electric systems to extend the range of hybrid electric vehicles. HOW DOES AN INTERNAL COMBUSTION ENGINE WORK? Combustion, also known as burning, is the basic chemical process of releasing energy from a fuel and air mixture. In an internal combustion engine (ICE), the ignition and combustion of the fuel occurs within the engine itself. The engine then partially converts the energy from the combustion to work. The engine consists of a fixed cylinder and a moving piston. The expanding combustion gases push the piston, which in turn rotates the crankshaft. Ultimately, through a system of gears in the powertrain, this motion drives the vehicle's wheels. There are two kinds of internal combustion engines currently in production: the spark ignition gasoline engine and the compression ignition diesel engine. Most of these are four-stroke cycle engines, meaning four piston strokes are needed to complete a cycle. The cycle includes four distinct processes: intake, compression, combustion and power stroke, and exhaust. Spark ignition gasoline and compression ignition diesel engines differ in how they supply and ignite the fuel. In a spark ignition engine, the fuel is mixed with air and then inducted into the cylinder during the intake process. After the piston compresses the fuel-air mixture, the spark ignites it, causing combustion. The expansion of the combustion gases pushes the piston during the power stroke. In a diesel engine, only air is inducted into the engine and then compressed. Diesel and gasoline engines then spray the fuel into the hot compressed air at a suitable, measured rate, causing it to ignite. IMPROVING COMBUSTION ENGINES Over the last 30 years, research and development has helped manufacturers reduce ICE emissions of criteria pollutants, such as nitrogen oxides (NOx) and particulate matter (PM) by more than 99% to comply with EPA emissions standards. Research has also led to improvements in ICE performance (horsepower and 0-60 mph acceleration time) and efficiency, helping manufacturers maintain or increase fuel economy. Learn more about our advanced combustion engine research and development efforts focused on making internal combustion engines more energy efficient with minimal emissions with inverter generator. How Gasoline Engines Can Survive in an Electric Car Future Combustion engines won't completely disappear any time soon, if ever. Certain transportation tasks or operating environments simply don't lend themselves to battery- or hydrogen-powered electric propulsion. A century and a half of research and development has greatly increased the efficiency of combustion engines, and engineers have loads of additional tricks up their sleeves that promise to extract even more work from a molecule of fuel while producing even fewer harmful emissions. Here are but a few we're keeping our eyes on, listed in order of complexity and cost to implement. A 98-Octane Fuel Standard Simply being able to design an engine to run 15:1 or higher compression greatly improves its thermodynamic efficiency and power density, permitting further engine downsizing. That requires higher-octane fuel, and a research-octane number (RON) of 98 represents a sweet spot, above which producing/refining the fuel consumes more energy, decreasing the well-to-wheels energy/CO2 benefit. Smart Cylinder Deactivation Engines are sized for worst-case scenarios like quarter-mile acceleration or towing heavy trailers up Davis Dam. Cylinder deactivation improves efficiency during less extreme driving situations by making a few cylinders work Davis Dam hard while the others do nothing. Dynamic Fuel Management can shut off any or all cylinders in GM's 5.3- and 6.2-liter V-8s to boost EPA fuel economy by up nearly 12 percent. Tula Technologies and Eaton now propose similar systems for long-haul diesel engines, where a smaller fuel efficiency payoff (1.5-4.0 percent) pays huge NOx dividends by maintaining exhaust temperatures needed to keep catalysts lit. An engine's power is limited by the amount of air it can ingest, which is why crankshaft-powered superchargers and exhaust-powered turbochargers were developed more than a century ago. Electric superchargers using recovered energy power the the Volvo Drive E and Mercedes M256 engines, among others; adding a motor/generator to a turbocharger eliminates lag under power and permits energy harvesting while cruising. Two interesting riffs on crank-powered superchargers are the Torotrak V-Charge centrifugal blower, which employs a CVT to quickly match speed to demand, and Hansen Engine Corp's Lysholm-type blower, which features a window that opens or closes to match demand for air pressure while minimizing losses to deliver turbo efficiency with supercharged responsiveness.
Дата Публикации: 03-11-22
Why Glass Is Best For Storing Food
Описание: Why Glass Is Best For Storing Food We know glass is 100% recyclable, but why is it better for storing food and choosing in the supermarket? We take a look. Have you ever wondered what the best type of container is for recycling and reducing your plastic waste? Ever stood in the supermarket trying to decide what kind of container to buy something in? Glass, tin or plastic? Glass has a lot going for it in terms of being a recyclable resource so we thought we'd look at just why glass storage jars are a great eco-friendly option at home. a Why Glass Is Best For Storing Food 1. Glass is endlessly recyclable Glass doesn't degrade every time you recycle it (unlike all recycled plastics). It can be recycled into another jar or bottle that's just as good over and over again, without ever reducing its quality. Did you know it only takes around 30 days for your old glass wine bottle to be recycled and be back on the shelf made into something else? Without their lids, glass jars and glass kettle are made of one simple material which is easily recycled. Plus making glass from recycled glass that already exists reduces the CO2 emissions compared to making it from scratch, says consumer movement Friends of Glass. As well as reusing your glass storage containers to house any number of pickles, dry goods and sauces, you can even recycle your glass jar into candle jars at home. 2. Glass is inert Recyclable glass jars keep food and drink fresher for longer, because unlike other packaging materials, glass is inert and needs no chemical layer between it and the food in question. It also doesn't affect the taste of any food. 3. Glass is non toxic Glass is made of three materials - soda ash, sand and limestone - which are non toxic. No chemicals can leach into food from glass jars or glass wine set because there aren't any and glass doesn't react with any types of food. 4. Less glass is being used While glass can be heavy, new manufacturing and recycling methods are being used to use less glass to make items like wine bottles lighter, yet just as strong. The weight of the average glass bottle has reduced by 40% over the last 15 years. What store cupboard staples do you buy in glass cup bottles?
Дата Публикации: 03-11-22
Fan Types - Why choose a forward curved centrifugal fan
Описание: Fan Types - Why choose a forward curved centrifugal fan Forward Curved Motorised Impeller When we have defined the volume flow rate that we require, whether this is to provide fresh air or process cooling, we need to combine this with the resistance to flow that the fan will encounter in the application. The volume flow rate, (in m3/hr) and the pressure (in Pascals - Pa), are combined to become the duty point against which the fan must operate. It is important that we select a fan whose performance characteristic meets the required duty point on or near the point of peak efficiency. Using the fan at its peak efficiency minimises the power consumption and noise emitted from the fan whilst delivering the required performance. How does Forward Curved Centrifugal Fan work? The name, 'Centrifugal Fan' is derived from the direction of flow and how the air enters the impeller in an axial direction and then propelled outwards from the outer circumference of the fan. The difference in flow direction between a forward and backward curved centrifugal fan is the direction that the air exits the impeller circumference. With a backward curved impeller, the air exits in a radial direction whereas with a forward curved the air exits tangentially from the circumference of the fan. A forward curved centrifugal fan is characterised by its cylindrical shape and lots of small blades on the circumference of the impeller. In the example shown below, the fan rotates in a clockwise direction. Unlike the backward curved impeller, the forward curved impeller requires a housing that converts high velocity air leaving the tips of the impeller blade into a lower velocity static force. The shape of the housing also directs the air flow to the outlet. This type of fan housing is commonly known as a scroll; however, it can also be referred to as a volute or a sirocco housing. By installing the forward curved impeller in a scroll housing, we usually refer to it as a forward curved blower. There are two types of blowers that employ a forward curved motorised impeller as shown below… The single inlet blower on the left, draws in air from one side of the housing through the round inlet and directs it to the square outlet, (seen here with a mounting flange). The double inlet blower has a wider scroll housing drawing air in from both sides of the scroll delivering it to the wider square outlet. As with the backward curved centrifugal fan, the suction side of the impeller blade draws air from the centre of the cross flow fan which results in a directional change of the airflow between the inlet and the exhaust of 90o. Fan Characteristic The optimum operating area for a forward curved centrifugal fan is when it is operating at higher pressure. A forward curved centrifugal fan works best when high pressures against lower volume flows are required. The graph below illustrates the optimum working area… The volume flow is plotted along the X-axis and the system pressure is plotted on the Y-axis. When there is no pressure in the system, (the fan is blowing freely), a forward or backward curved centrifugal fan will produce the greatest volume flow. As a resistance to flow is applied to the suction or exhaust side of the fan, the volume flow rate will drop. Caution should be exercised when selecting a forward curved blower to operate at low pressures and highest volume flow. At this point, the impeller is operating in an aerodynamic stall in the same manner as an axial flow fan operating in the saddle point of its curve. At this point noise and power consumption will be at its peak due to turbulence. The peak efficiency is at a point called the knee of the characteristic curve. At this point the ratio of the output power of the fan (Volume flow (m3/s) x Static Pressure development (Pa) and the electrical power input (W) is at its greatest and the sound pressure being produced by the fan will be at its quietest. Above and below the optimum range of operation the flow across the fan becomes noisier and the efficiency of the fan system decreases. The benefit of using a single inlet forward curved motorised impeller is that it has a steep fan characteristic. This is particularly useful in systems that require consistent levels of filtration. As air passes through a particulate filter the filter arrests airborne dust and pollen, the finer the grade of filtration the smaller the particles arrested by the filter. Over time the filter will become increasingly clogged with dirt and debris which has the effect that more pressure is required to deliver the same air volume. Using an impeller with a steep characteristic curve in this case means that as the filter becomes increasingly clogged, the volume flow remains constant while the pressure across the filter is increasing. The benefit of using a double inlet forward curved impeller is that from a relatively small size blower it can deliver a high-volume flow. The compromise with using a double inlet blower is that it has a lower pressure development meaning that it can only work with lower pressure systems. Mounting options As mentioned previously, the forward curved motorised impeller produces high velocity air at the tips of the blade that needs to be directed and slowed to convert dynamic pressure into static pressure. To facilitate this, we build a scroll around the impeller. The shape is created by a ratio of distances from the centre of the impeller to the fan outlet. As with the backward curved fan it is also recommended to have a small overlap between the inlet ring and the mouth of the impeller. Both mounting considerations are shown in the diagram below… Summary – Why Choose a forward curved centrifugal fan? When the required duty point falls in the area of higher system pressures versus lower volume flow on the fan characteristic a single inlet forward curved centrifugal fan should be considered. If the requirement for the application is for a high-volume flow in a restricted space envelope a double inlet forward curved centrifugal fan should be considered. The fan should be selected within its optimum range which is at what is known as the knee of its characteristic curve. The point of peak efficiency is in the closer to the higher-pressure limit on the fan characteristic curve where it is also being operating at its quietest. Operating outside of the optimum range (at the extremes of high volume flow) should be avoided as the turbulence and the aerodynamic efficiency of the impeller blade at these points will create noise and the impeller will also be operating in an aerodynamic stall. At low pressures and high-volume flows consideration should be given to the operating temperature of the motor under load as there is a potential for a motor overheat to occur. Air on the inlet side of the impeller should be kept as smooth and laminar as possible. To maximise the efficiency at least a clearance of 1/3rd of the impeller diameter should be allowed on the fan inlet. Using an inlet ring (Inlet nozzle) overlapping the impeller inlet will help to eliminate flow disturbances before the air is drawn through the fan, reduce turbulence induced noise, keep the power consumption at the duty point to a minimum and maximise efficiency.
Дата Публикации: 03-11-22
There's an Art to Making Your Bed
Описание: There's an Art to Making Your Bed You can start by disregarding thread count. Here's what else the pros know that you may not. If you want your bedroom to serve as a refuge from daily stress, one piece of furniture is more important than all the rest: the bed. But you need to do more than just choose a good mattress and bed frame. How you dress the bed — whether you create a pared-down crash pad of white linen, say, or a mountain of down topped by a pile of colorful pillows — affects the way a room feels. It's similar to fashion, said Deanna Wu, the vice president of merchandising at the bedding company Brooklinen: The way you dress your bed should communicate something about how you want to live. "Do you want it to have colors, layers of texture and a feeling of whimsy? Or do you want it calm?" she asked. "You can dress your bed as you dress yourself. It can be a reflection of your mood and style." We asked interior designers and bedding experts for advice on the basics, from fitted sheets to decorative throw pillows, as well as tips for dressing a bed that looks appealing during the day and encourages snuggling at night. Begin With the Sheets Sheets are the undergarments of the bed: You won't see much of them when the bed is fully dressed, but they have a noticeable effect on comfort because they're in direct contact with your skin. High-quality sheets are most frequently offered in different cotton weaves, usually percale or sateen, or in linen, and no choice is better than the others. It all depends on personal preference. Cotton percale is a plain weave with a relatively matte look and feel. "It's a very breathable fabric, and kind of crisp and cool to the touch," said Anki Spets, the founder of the bedding company Area. "You can even put your hand on it in the store, and the percale will feel cooler than the sateen." Percale is popular with people who often feel too hot under the covers. Sateen sheets are woven to offer a silkier, luxurious feel. "It has a much smoother top finish," Ms. Spets said. "It's so soft, it's irresistible when you touch it. But they can also feel a little warmer to sleep in, so that's where you have to know what you like." Linen sheets are another popular option, but they aren't for everyone. "They have a more organic, earthy look," Ms. Spets said, with a more noticeable texture. They also have a tendency to show wrinkles, a quality that some people view as problematic but others prize as a sign of relaxed, informal living. High-quality linen sheets tend to breathe well and absorb moisture, so they feel cool like percale, Ms. Spets said, while lower-quality options may be thicker and warmer, or even feel rough against the skin. Choose sheets by feel and appearance rather than thread count. An extremely high thread count, once seen as a sign of quality, doesn't count for much anymore because it's possible to inflate the number while using lower-quality fibers. "Thread count is more of a marketing tool that was brought out in the early 2000s," said Jenifer Foley, the lead stylist at Frette, adding that higher thread counts can sometimes result in thicker, less breathable sheets. What's underneath the fitted sheet matters too. If your mattress isn't as comfortable as you'd like, consider adding a mattress pad. "I like to start with a really nice mattress pad that gives you a little padding underneath the sheet," said Chad Dorsey, an interior designer based in Dallas, who frequently uses a Hotel Collection pad from Macy's. "It doesn't get too hot and has just the right amount of volume." Add Layers for Warmth There are two basic strategies for bringing warmth to a bed: adding a duvet or using a bedspread, sometimes in combination with a blanket, just like a seat cushion. For years, down-filled duvets, wrapped in duvet covers, have been de rigueur. They are so fluffy, comforting and good at regulating temperature that many people abandon their top sheets altogether, adopting a European-style approach to making a bed with a fitted sheet and a duvet — and nothing else. If you don't use a top sheet, the choice of fabric for your duvet cover matters more, and it should have a similar feel to that of your fitted sheet. For that reason, some duvet covers are made with a sandwich of two materials. "A lot of our duvet covers that have an ornate jacquard on the top, the underside is actually just a plain sateen weave, so what's touching your skin is still soft," Ms. Foley said. One advantage to this way of dressing a bed is that it's easy to make it in the morning — just pull up the duvet and you're done. Of course, it's perfectly acceptable to use a top sheet with a duvet, if you prefer. In that case, Ms. Foley recommended folding the top sheet over the top 15 inches of the duvet, at the head of the bed, for comfort and a decorative touch. But now bedspreads, coverlets and quilts — once elbowed out by duvets — are making a comeback. Many interior designers are embracing them, and companies like Coyuchi, Parachute Home and Hale Mercantile are introducing more options."Five years ago, it was always about this chunky duvet you had to deal with, and it was impossible to find a bedspread," said Jayne Michaels, a founder of the New York-based interior design firm 2Michaels. "Now it's changed, and you can find great coverlets and bedspreads again, which we prefer." A bedspread allows your bedding to change with the seasons, Ms. Michaels said, by making it easy to layer wool blankets underneath in the winter and to remove those blankets in the summer. The look of the bed also tends to be more tailored than a bed with a duvet. If you can't decide which approach is best, it's possible to do both. Mr. Dorsey has dressed some beds with a bedspread before adding a folded duvet at the foot of the bed. Other designers do the opposite and cover the mattress with a duvet, then place a thin, folded quilt at the end. Add Pillows There are two types of pillows: those used for sleeping and those used for decorative purposes and sitting up in bed. For a typical queen-size bed, you need a minimum of two sleeping lumbar cushion pillows in your preferred level of firmness (or a single Gel bedding memory foam pillow for a twin bed). But many designers use more. "Typically, four for sleeping," Mr. Dorsey said. "Maybe two medium, and then two very soft." Those pillows should be stuffed into pillowcases that have a similar feel to your sheets. "You can have two that match the sheets," Ms. Spets said, "and then you can have two that have another color or something that makes it more interesting."
Дата Публикации: 03-11-22
The Advantages and Disadvantages of HDPE Geomembrane Liner
Описание: The Advantages and Disadvantages of HDPE Geomembrane Liner To build a pond, landfill, dam, or lake, and so on, the first thing is to choose the waterproof impermeable liner. But, there are many kinds of flexible liners — often called "geomembranes". Your liner should stay stable under the hottest and coldest temperatures your area may experience, and it should not be damaged, punctured, or torn as the objects or irregularities. If the liner is exposed, it must be anti-UV. Chemical resistance, flexibility, the cost can all vary as well. For these reasons, it is better to know a little about different liner materials before you invest. HDPE Geomembrane (High-Density Polyethylene Geomembrane) HDPE Geomembrane Liner has a very good UV resistance and functions well in cold temperatures. It is also strong and very stiff. HDPE Geomembrane Liner's most desirable characteristic, though, might be its superior resistance to a wide range of chemicals. With its cheap price and the fact that many sheets can be joined using a welding machinery and accessories, HDPE Geomembrane become one of the most popular geomembrane types worldwide. HDPE Geomembrane Liner is used for landfills and chemical containment projects, but it is also safe and well-suited for fish ponds.HDPE Geomembrane Liner is very durable, the life can last upwards of 50 years when covered. Unfortunately, HDPE Geomembrane Liner is far from perfect, Because it is stiff and heavy, HDPE Geomembrane Liner may be expensive to ship and can't be customized shaped or assembled in a factory. Instead, you'll have to pay extra installation costs to install on-site by professionals. These expenses make HDPE Geomembrane Liner most cost-effective for larger projects. HDPE Geomembrane Liner's lack of flexibility can also make installation more difficult, You must be careful when installing the HDPE Geomembrane Liner on the rough subgrade, since the material is vulnerable to punctures, and surface scratches that can become cracks over time. HDPE Geomembrane Liner Advantages: Excellent chemical resistance Good UV resistance Cheap Weldable Fish safe Very durable 50years lifespan when covered Performs well in cold temperatures HDPE Geomembrane Liner Disadvantages: Poor flexibility Heavyweight makes it more expensive to ship, difficult to install Less custom fabrication; welded on-location Poor resistance to stress cracking Comparing various geomembranes for your next geosynthetic application? Don't overlook high-density polyethylene (HDPE) LLDPE geomembrane. HDPE has been in use for decades and during that time a number of studies have been conducted to test its longevity and ability to meet environmental sustainability project requirements. Here, we explore some of those studies to examine the benefits of HDPE compared with other geomembranes types such as polyvinyl chloride (PVC). How Does HDPE Compare With PVC and Other Geomembrane Types? As a waterproofing liner, a HDPE geomembrane is favored over other materials for its modest economic and operational advantage. Economically, HDPE geomembrane is superior thanks to its relatively straightforward manufacturing process, which has driven up supply and kept prices low in contrast to other kinds of geomembranes. As more design engineers become familiar with the material, growing competence in its use further promotes its market dominance and economic edge over competing products. Secondly, HDPE has been favored for its physical properties (See Table 1). While tests run on PVC and HDPE show very few practical differences, HDPE does tend to outperform PVC and other geomembranes in areas such as resistance to folding damage and dynamic impact (2). Furthermore, the material is a very stable polyolefin that is chemically inert and able to maintain long-term integrity and durability. These properties make the HDPE geomembrane a popular choice to waterproof and seal landfills and other containment applications. HDPE geomembrane can also be manufactured with additives to amplify certain qualities. How Does the HDPE Geomembrane Contribute to Environmental Sustainability? Compared with other geomembranes, HDPE has the highest theoretical unexposed service life at >100 years. This high service life potential makes HDPE a powerful tool for environmental sustainability efforts such as the safe closure of a landfill. In the case of exposed liner, one study, a HDPE geomembrane exposed to 10 years of ultraviolet radiation and wastewater showed no significant change in physical properties (e.g., tensile, tear, puncture, and carbon black). The only observed difference was in tensile elongation and melt index, both believed to be a result of material cross-linking as a result of UV exposure. However, sunlight exposure over the 10-year period did little to impact most of the material's properties insomuch that it was nearly indistinguishable from a newly manufactured sample (3). The study demonstrates the capable role of HDPE geomembrane in environmental sustainability. Furthermore, it suggests that today's HDPE can be expected to perform at a higher level thanks to technological improvements in resin stabilization and sheet manufacturing techniques.
Дата Публикации: 03-11-22
The 13 Types of Flanges for Piping Explained
Описание: The 13 Types of Flanges for Piping Explained Which are the most common types of flanges used in piping? How do they look like? The key types of flanges are the welding neck, long welding neck, slip-on flanges, socket weld, lap joint, threaded and blind flanges. In addition to these standard flanges, some special ones exist, called Weldoflange/Nipoflange and Elboflange, swivel flange, expander/reducer flange, and orifice flanges. STANDARD TYPES OF FLANGES The type of flange to be used for a piping application depends, mainly, on the required strength for the flanged joint. Flanges are used, alternatively to welded connections, to facilitate maintenance operations (a flanged joint can be dismantled quickly and conveniently). Let's now dive in, showing the key types of flanges with pictures. WELDING NECK FLANGE STANDARD TYPES OF FLANGES The type of flange to be used for a piping application depends, mainly, on the required strength for the flanged joint. Flanges are used, alternatively to welded connections, to facilitate maintenance operations (a flanged joint can be dismantled quickly and conveniently). Let's now dive in, showing the key types of flanges with pictures. WELDING NECK FLANGE Long weld neck flanges ("LWN") are similar to welding neck flanges, with the exception that the neck (tapered hub) is extended and acts like a boring extension. Long weld neck flanges are generally used on vessels, columns or barrels. These flange types are available also in the heavy barrel (HB) and equal barrel (E) types. SLIP ON FLANGE A slip-on flange is connected to the pipe or the fittings by two fillet welds, one executed inside and one outside the cavity of the flange. The bore size of a slip-on flange is larger than the outside diameter of the connecting pipe, as the pipe has to slide inside the flange to be connected by the execution of a fillet weld. Slip-on flanges are also defined "Hubbed Flanges" and they are easy to recognize due to their slim and compact shape. The dimensions and weights of slip-on flanges ANSI/ASME are available on this page. WELD NECK VS SLIP ON FLANGE Flanged joints made with slip-on flanges are, in the long run, a bit more fragile than connections made with welding neck flanges (in similar service conditions). This seems due to the following facts: a welding neck flange features a tapered hub, absent in a socket weld flange, which distributes the mechanical stress between the pipe and the flange more evenly a welding neck joint as only one welding area instead of two (socket weld flange). Another advantage of the welding neck flange is that it can be connected either to pipes and fittings, whereas socket weld flanges suit pipes only. THREADED FLANGE Threaded flanges are joined to pipes by screwing the pipe (which has a male thread, generally NPT per ASME B1.20.1) onto the flange, without seam welds (in certain cases, though, small welds are applied to increase the strength of the connection). Threaded flanges are available in sizes up to 4 inches and multiple pressure ratings, however, they are used, mostly, small size piping in low pressure and low-temperature applications, like water and air utility services. Threaded flanges are also a mandatory requirement in explosive areas, such as gas stations and plants, as the execution of welded connections in such environments would be dangerous. Consult this article, to find about the dimension of ANSI/ASME threaded flanges. SOCKET WELD FLANGE Socket weld flanges are connected to pipes using a single fillet weld executed on the outer side of the flange (different from the slip-on flange type that requires two welds). According to ASME B31.1, to execute a flanged connection using a socket weld flange, the pipe shall be at first inserted in the socket of the flange until it reaches the bottom of the flange, then it should be lifted by 1.6 mm and finally welded. This gap shall be left to allow proper positioning of the pipe inside the flange socket after the solidification of the weld. Socket Weld Flanges are used for small-size and high-pressure piping that do not transfer highly corrosive fluids. This due to the fact that these flange types are subject to corrosion in the gap area between the end of the pipe and the shoulder of the socket. Their static strength of socket weld flanges is similar to slip-on flanges', but their fatigue strength is higher due to the presence of a single, instead of double, fillet weld. LAP JOINT FLANGE Lap joint flanges feature a flat face and are always used in conjunction with a stub end. Lap joint flanges resemble, in shape, slip-on flanges except for the radius at the crossing of the flange face and the bore to accommodate the flanged portion of the stub end. A lap joint flange slips over the pipe and seats on the back of the stub end and the two are kept together by the pressure of the bolts. The use of lap joint flanges in combination with stub ends is a cost-effective solution for stainless steel or nickel alloy pipelines, as the material of the lap joint flange can be of a lower grade (generally carbon steel) than the material of the stub end (which has to match the pipe grade, as in contact with the conveyed fluid). This arrangement, therefore, has these two advantages: reduces the overall cost of the pipeline's flanged joints, as the use of higher grade materials is minimized; bolting operations are simplified, as the lap joint flange can be rotated around the pipe to help with bolts alignment. The dimensions and weights of lap joint flanges are shown in this article. BLIND FLANGE Contrary to all the flange types seen above, blind flanges do not have a center hole, and are used to blind or seal a pipeline, a valve/pressure vessel and block the flow of the fluid. Blind flanges have to withstand remarkable mechanical stress due to the system pressure and the required bolting forces. Blind flanges allow easy access to the pipeline, as they can be easily unbolted to let the operator execute activities inside the terminal end of the pipe (this is also the reason why the blind flange type is used as manhole for pressure vessels, at times). It is maybe interesting to observe that, while this flanges type is easier to manufacture, they are sold at a premium average cost per kilogram compared to the other flange types.
Дата Публикации: 03-11-22
Wire Rope Clips: Different Types, Installation, and Common Mistakes
Описание: Wire Rope Clips: Different Types, Installation, and Common Mistakes Wire rope is an extremely versatile mechanical device that can be used to help support and move an object or load. Whether for use on cranes or for other lifting applications, it's important to have a solid understanding of the rigging components that are being used to attach to and lift a load. As a rigger or end-user of wire rope, it's necessary to understand the types of wire rope end termination, or treatments that can be used at the ends of a length of wire rope—one of the most common being wire rope clips. In this article, you can expect to learn: What a wire rope clip is Types of wire rope clips Common mistakes when using wire rope clips Steps to install a wire rope clip What is a Wire Rope Clip? Wire rope clips can be used to form a load bearing eye at the end of a cable or wire rope, or to connect two cables together with a lap splice. Wire rope clips are popular because they can be installed in the field and provide 80-90% efficiency of the rope breaking strength, depending on the diameter of the wire rope. As a general guideline, they are NOT to be used for making slings, as ASME B30.9 Slings standard states: "Mechanical wire rope terminations requiring periodic adjustment to maintain efficiency shall not be used to fabricate slings." Examples of situations where a wire rope clip could be utilized include: Wire rope end termination on a crane cable or winch To run a length of wire rope through an eye bolt or shackle Perimeter cables on docks, parking lots, etc. There are two main types of wire rope clips—U-Bolt and double saddle clips. U-Bolt wire rope clips are the most common and may be made of forged or malleable metal. U-Bolt Wire Rope Clips This type of wire rope clip is essentially a U-bolt, two nuts, and a metal base (saddle) that can be made from forged steel or cast iron. Careful consideration and attention must be given to the way U-bolt type wire rope clips are installed. Forged Wire Rope Clips The base of the wire rope clip is made from forged steel. Forged clips are heated and hammered into the desired shape—resulting in a consistent grain structure in the steel. Forged wire rope clips are used for critical, heavy-duty, overhead loads such as winch lines, crane hoist lines, support lines, guy lines, towing lines, tie downs, scaffolds, etc. Malleable Wire Rope Clips Malleable wire rope clips are used for making eye termination assemblies only with right regular lay wire rope and only for light duty uses with small applied loads, such as hand rails, fencing, guard rails, etc. The base of the wire rope clips is made from malleable cast iron, which may fracture under heavy use and does not have the desirable metal properties of steel, or the beneficial grain structure that a forged base has. Double Saddle Wire Rope Clips Double saddle wire rope clips consist of two saddles, each with a leg, and two nuts—one used on the top and one on the bottom. Double saddle wire rope clips can be used in either direction, so they take the guesswork out during installation when applying to the live end and the dead end of a piece of wire rope.
Дата Публикации: 03-11-22