query: the function of a bursa is to reduce friction

pos: Synovial bursa Synovial bursa A synovial bursa (plural bursae or bursas) is a small fluid-filled sac lined by synovial membrane with an inner capillary layer of viscous synovial fluid (similar in consistency to that of a raw egg white). It provides a cushion between bones and tendons and/or muscles around a joint. This helps to reduce friction between the bones and allows free movement. Bursae are found around most major joints of the body. There are four types of bursa: adventitious, subcutaneous, synovial, and sub-muscular. Among these, only adventitious is non-native. When any surface of the body is subjected to repeated stress,

neg: Subcoracoid bursa Subcoracoid bursa The subcoracoid bursa or subcoracoid bursa of Collas is a synovial bursa located in the shoulder. It is located anterior to the subscapularis muscle and inferior to the coracoid process. Its function is to reduce friction between the coracobrachialis, subscapularis and short head of the biceps tendons, thus facilitating internal and external rotation of the shoulder. The subcoracoid bursa does not communicate with the glenohumeral joint under normal circumstances, but may communicate with the subacromial bursa. As such, contrast fluid injected into the glenohumeral joint during an arthrogram that extends into the subcoracoid bursa is abnormal, and indirectly

neg: Subcoracoid bursa implies a full thickness rotator cuff tear. Subcoracoid bursa The subcoracoid bursa or subcoracoid bursa of Collas is a synovial bursa located in the shoulder. It is located anterior to the subscapularis muscle and inferior to the coracoid process. Its function is to reduce friction between the coracobrachialis, subscapularis and short head of the biceps tendons, thus facilitating internal and external rotation of the shoulder. The subcoracoid bursa does not communicate with the glenohumeral joint under normal circumstances, but may communicate with the subacromial bursa. As such, contrast fluid injected into the glenohumeral joint during an arthrogram that extends into

neg: Prepatellar bursitis infection is present, often accompanied by fever. Unlike arthritis, except in severe cases prepatellar bursitis generally does not affect the range of motion of the knee, though it may cause some discomfort in complete flexion of the joint. Flexion and extension of the knee may be accompanied by crepitus, the audible grating of bones, ligaments, or particles within the excess synovial fluid. In human anatomy, a "bursa" is a small pouch filled with synovial fluid. Its purpose is to reduce friction between adjacent structures. The prepatellar bursa is one of several bursae of the knee joint, and is located between

neg: Greater trochanteric pain syndrome relieve pain and reduce the inflammation. If these are ineffective, the definitive treatment is steroid injection into the inflamed area. Physical therapy to strengthen the hip muscles and stretch the iliotibial band can relieve tension in the hip and reduce friction. The use of point ultrasound may be helpful, and is undergoing clinical trials. In extreme cases, where the pain does not improve after physical therapy, cortisone shots, and anti-inflammatory medication, the inflamed bursa can be removed surgically. The procedure is known as a bursectomy. Tears in the muscles may also be repaired, and loose material from arthritic degeneration of

neg: Subacromial bursa Subacromial bursa The subacromial bursa is the synovial cavity located just below the acromion, which communicates with the subdeltoid bursa in most individuals, forming the so-called subacromial-subdeltoid bursa (SSB). The SSB bursa is located deep to the deltoid muscle and the coracoacromial arch and extends laterally beyond the humeral attachment of the rotator cuff, anteriorly to overlie the intertubercular groove, medially to the acromioclavicular joint, and posteriorly over the rotator cuff. The SSB decreases friction and allows free motion of the rotator cuff relative to the coracoacromial arch and the deltoid muscle. French anatomist and surgeon, Jean-François Jarjavay is credited

neg: Pes anserine bursitis and E-stim deliver medication deep to the bursa to reduce inflammation. The rehabilitative exercises are done with the intention of stretching and strengthening the hip abductors, quadriceps, and hamstrings. These stretches have the potential to significantly reduce the tension over the pes anserine bursa. Pes anserine bursitis Pes anserine bursitis is an inflammatory condition of the medial (inner) knee at the anserine bursa, a sub muscular bursa, just below the pes anserinus. The pes anserinus is the insertion of the conjoined tendons sartorius, gracilis, and semitendinosus into the anteromedial proximal tibia. Theoretically, bursitis results from stress to this area (e.g.

neg: Forces on sails friction of the water (for boats) or air (for ice boats and land sailing craft) against the "skin" of the hull that is moving through it. Displacement vessels are also subject to wave resistance from the energy that goes into displacing water into waves and that is limited by hull speed, which is a function of waterline length, Wheeled vehicles' forward speed is subject to rolling friction and ice boats are subject to kinetic or sliding friction. Parasitic drag in water or air increases with the square of speed ("V" or "V", respectively); Ways to reduce wave-making resistance used on

neg: Lubricant Lubricant A lubricant is a substance, usually organic, introduced to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, transporting foreign particles, or heating or cooling the surfaces. The property of reducing friction is known as lubricity. In addition to industrial applications, lubricants are used for many other purposes. Other uses include cooking (oils and fats in use in frying pans, in baking to prevent food sticking), bioapplications on humans (e.g. lubricants for artificial joints), ultrasound examination, medical examination. Lubicants have been in

neg: Turn board and subtle variations in design. Generally, the turn boards will be 10 – 12 inches in length, and 3-4 inches in width as it is a platform for a foot. Turn boards have an arched shape to reduce the boards touchpoint on the ground, and to allow for turning flat footed. Thus causing less friction and more ease of spinning. Generally, the boards are made of wood or a plastic composite that has a friction reducing component, and come in a variety of colors and features. Turning boards normally function through proper application of the law of physics by reducing

neg: Friction modifier Friction modifier Friction modifiers are added to lubricants in order to reduce friction and wear in machine components. They are particularly important in the boundary lubrication regime, where they can prevent solid surfaces from coming into direct contact, substantially reducing friction and wear. Several classes of friction modifier additives exist, the main examples being organic friction modifiers (OFMs), oil-soluble organo-molybdenum additives, functionalized polymers, and dispersed nanoparticles. Reduction of frictional losses and through more efficient lubrication is a key target in order to reduce carbon dioxide emissions. One approach has been to progressively reduce lubricant viscosity to minimize hydrodynamic shear, churning

neg: Bursitis muscle or tendon. When the bone increases pressure upon the bursa, bursitis results. Sometimes the cause is unknown. It can also be associated with various other chronic systemic diseases. The most common examples of this condition: It is important to differentiate between infected and non-infected bursitis. People may have surrounding cellulitis and systemic symptoms include a fever. The bursa should be aspirated to rule out an infectious process. Bursae that are not infected can be treated symptomatically with rest, ice, elevation, physiotherapy, anti-inflammatory drugs and pain medication. Since bursitis is caused by increased friction from the adjacent structures, a compression

neg: Bursitis bandage is not suggested because compression would create more friction around the joint. Chronic bursitis can be amenable to bursectomy and aspiration. Bursae that are infected require further investigation and antibiotic therapy. Steroid therapy may also be considered. In cases when all conservative treatment fails, surgical therapy may be necessary. In a bursectomy the bursa is cut out either endoscopically or with open surgery. The bursa grows back in place after a couple of weeks but without any inflammatory component. Bursitis Bursitis is the inflammation of one or more bursae (small sacs) of synovial fluid in the body. They are

neg: Navicular syndrome researchers to conclude that there are elements in navicular disease common to osteoarthritis, and to suggest similar therapeutic regimes. Cartilage erosion may progress to the point that the bone underneath will become exposed. With the cartilage no longer present to protect it, the navicular bursa and DDF tendon may become damaged by the constant rubbing against the navicular bone. Navicular bursitis (inflammation of the navicular bursa) may occur, even if cartilage damage is not severe. This is probably due to the friction between the navicular bone and the DDF tendon from compression. Constant compression can also increase the bone density

neg: Piezoelectricity friction of a clamp. Such motors can be very small. Some are used for camera sensor displacement, thus allowing an anti-shake function. Different teams of researchers have been investigating ways to reduce vibrations in materials by attaching piezo elements to the material. When the material is bent by a vibration in one direction, the vibration-reduction system responds to the bend and sends electric power to the piezo element to bend in the other direction. Future applications of this technology are expected in cars and houses to reduce noise. Further applications to flexible structures, such as shells and plates, have also

neg: Dry suit suit, and function as short gaiters to constrict the ankle region of suit once the foot is in the boot. Ankle-weights have to be accelerated and decelerated along with the fins during every kick, which requires more energy from the diver. Gaiters do not have this drawback as they are typically very light and approximately neutral buoyancy. To reduce the contact with latex seals in divers with a latex allergy, a soft elastomer band called a "Bio-seal" can be worn under the latex contact area. These may also reduce friction with the seal and improve watertightness. For applications where passive

neg: Avian immune system clonal selection and expansion, avian T cells cease to express either CD4 or CD8. The central organ for B cell development in birds is the Bursa of Fabricius. The function of the bursa was discovered when it was surgically removed from neonatal chicks and this led to an impaired antibody response to "Salmonella typhimurium". It is now clear that the bursa is the primary site of B cell lymphopoeisis and that avian B cell development has some unique properties compared to human or mouse models. Almost all the B cell progenitors in the bursa of 4-day-old chickens express IgM on

neg: Chicken as biological research model Discoveries in the chicken ultimately divided the adaptive immune response into antibody (B-cell) and cell-mediated (T-cell) responses. Chickens missing their bursa, an organ with an unknown function at the time, could not be induced to make antibodies. Through these experiments, Bruce Glick, correctly deduced that bursa was responsible for making the cells that produced antibodies. Bursa cells were termed B-cells for Bursa to differentiate them from thymus derived T-cells. The chicken embryo is a unique model that overcomes many limitations to studying the biology of cancer in vivo. The chorioallantoic membrane (CAM), a well-vascularized extra-embryonic tissue located underneath the eggshell,

neg: Greater trochanteric pain syndrome Greater trochanteric pain syndrome Greater trochanteric pain syndrome (GTPS), also known as trochanteric bursitis, is inflammation of the trochanteric bursa, a part of the hip. This bursa is at the top, outer side of the femur, between the insertion of the gluteus medius and gluteus minimus muscles into the greater trochanter of the femur and the femoral shaft. It has the function, in common with other bursae, of working as a shock absorber and as a lubricant for the movement of the muscles adjacent to it. Occasionally, this bursa can become inflamed and clinically painful and tender. This condition can

neg: Supersonic airfoils lift at lower speeds, aircraft that employ supersonic airfoils also use high-lift devices such as leading edge and trailing edge flaps. At supersonic conditions, aircraft drag is originated due to: Therefore, the Drag coefficient on a supersonic airfoil is described by the following expression: C= C+ C+ C Experimental data allow us to reduce this expression to: C= C + KC Where C is the sum of C) and C, and k for supersonic flow is a function of the Mach number. The skin-friction component is derived from the presence of a viscous boundary layer which is infinitely close to

neg: Pallet fork in a disk on the balance wheel's shaft. To reduce friction, the pallets are made of precisely shaped pieces of ruby jewel. The pallet which the teeth first contact is called the "entry pallet", while the other one is called the "exit pallet". Under the fork there is a projecting "guard pin" which passes through a notch in a separate "safety roller" disk on the balance shaft. In normal operation it doesn't have a function. Its purpose is to make sure the fork is in the right position to receive the impulse pin if a jar to the watch prematurely

neg: Synovial sheath function is to reduce friction between the tendon and their surrounding structure. An example is the common synovial sheath for the flexor tendons of the hand. Synovial sheath A synovial sheath is one of the two membranes of a tendon sheath which covers a tendon. The other membrane is the outer fibrous tendon sheath. The tendon invaginates the synovial sheath from one side so that the tendon is suspended from the membrane by the mesotendon, through which the blood vessels reach the tendon, in places where the range of movement is extensive. The mesotendon disappears or remains in the form

neg: Speed skydiving while special helmets and slick body suits reduce skin friction, which is a function of surface area and texture. The shape and rigidity of the suits also have to be designed to minimize the coefficient of drag. Finally, a skydiver must reach their maximum speed at as high an altitude as possible so that the density of air is at a minimum. The International Speed Skydiving Association rules have altered over the years to accommodate the changes necessary. Some Speed Skydiving jargon involved is: The Measurement Zone: A vertical kilometer where speed measurements are taken. It starts at 2,700 m

neg: Foreskin role in newborns. He wrote, "It is often stated that the prepuce is a vestigial structure devoid of function... However, it seems to be no accident that during the years when the child is incontinent the glans is completely clothed by the prepuce, for, deprived of this protection, the glans becomes susceptible to injury from contact with sodden clothes or napkin." During the physical act of sex, the foreskin reduces friction, which can reduce the need for additional sources of lubrication. "Some medical researchers, however, claim circumcised men enjoy sex just fine and that, in view of recent research on

neg: Nanofluidics a function of Reynolds and Knudsen number using computational fluid dynamics . The relationship between lift, drag and Reynolds number has been shown to differ dramatically at the nanoscale compared with macroscale fluid dynamics. There are a variety of challenges associated with the flow of liquids through carbon nanotubes and nanopipes. A common occurrence is channel blocking due to large macromolecules in the liquid. Also, any insoluble debris in the liquid can easily clog the tube. A solution for this researchers are hoping to find is a low friction coating or channel materials that help reduce the blocking of the

neg: Circlip propensity of the clip's spring action to launch the clip at a high velocity when removing or installing, leading to remarks such as, "Oh Jesus, where did it go?" Because circlips are stamped out of sheet metal they have a smooth side and a rough side. The clip is installed with the smooth side facing the part and the rough side facing out, which prevents damage. Wet or dry lubrication is recommended to reduce friction against the circlip and maintain function. Circlips are designed to be removed with special pliers that can be reassembled for internal or external clips. For

neg: Fascia to be essentially avascular. However, more recent investigations confirmed a rich presence of thin blood vessels. Deep fascia is also richly supplied with sensory receptors. Examples of deep fascia are fascia lata, fascia cruris, brachial fascia, plantar fascia, thoracolumbar fascia and Buck's fascia. Fasciae were traditionally thought of as passive structures that transmit mechanical tension generated by muscular activities or external forces throughout the body. An important function of muscle fasciae is to reduce friction of muscular force. In doing so, fasciae provide a supportive and movable wrapping for nerves and blood vessels as they pass through and between muscles.

neg: Induction forging through the coil one behind the other on water cooled rails or ceramic liners are used through the coil bore which reduce friction and prevent wear. The length of the coil is a function of the required soak time, the cycle time per component and the length of the billet. In high volume large cross section work it is not unusual to have 4 or 5 coils in series to give of coil or more. Typical parts processed by in line billet heating: For long billets, single shot heating can be used. This process utilises similar systems to bar end

neg: Swim briefs The racing suit's main function is to reduce the drag of an athlete in water, thus improving his time. For this reason racing suits are made of materials that hug the body, minimize friction and minimize water retention. Spandex (Lycra) suits generally produce less drag, but are also more vulnerable to prolonged exposure to chlorine than nylon. Therefore, nylon suits are preferred for training and practice, where the increased durability is required for the long periods of usage and the extra resistance brings a training benefit. Lycra suits (and composite hi-tech swimwear fabrics) are preferred for actual racing. In water

neg: Human vestigiality a vestigial structure devoid of function... However, it seems to be no accident that during the years when the child is incontinent the glans is completely clothed by the prepuce, for, deprived of this protection, the glans becomes susceptible to injury from contact with sodden clothes or napkin.” During the physical act of sex, the foreskin reduces friction, which can reduce the need for additional sources of lubrication. "Some medical researchers, however, claim circumcised men enjoy sex just fine and that, in view of recent research on HIV transmission, the foreskin causes more trouble than it’s worth." The area of

neg: Motor oil Motor oil Motor oil, engine oil, or engine lubricant is any of various substances comprising base oils enhanced with additives, particularly antiwear additive plus detergents, dispersants and, for multi-grade oils viscosity index improvers. Motor oil is used for lubrication of internal combustion engines. The main function of motor oil is to reduce friction and wear on moving parts and to clean the engine from sludge (one of the functions of dispersants) and varnish (detergents). It also neutralizes acids that originate from fuel and from oxidation of the lubricant (detergents), improves sealing of piston rings, and cools the engine by carrying

neg: Meniscus (anatomy) the central meniscus is avascular by adulthood, leading to very poor healing rates. The menisci act to disperse the weight of the body and reduce friction during movement. Since the condyles of the femur and tibia meet at one point (which changes during flexion and extension), the menisci spread the load of the body's weight. This differs from sesamoid bones, which are made of osseous tissue and whose function primarily is to protect the nearby tendon and to increase its mechanical effect. In sports and orthopedics, people will sometimes speak of "torn cartilage" and actually be referring to an injury

neg: Aluminium magnesium boride in dry scratching by a diamond tip (cf. 0.04 for Teflon) and decreases to 0.02 in water-glycol-based lubricants. BAM is commercially available and is being studied for potential applications. For example, pistons, seals and blades on pumps could be coated with BAM or BAM + TiB to reduce friction between parts and to increase wear resistance. The reduction in friction would reduce energy use. BAM could also be coated onto cutting tools. The reduced friction would lessen the force necessary to cut an object, extend tool life, and possibly allow increased cutting speeds. Coatings only 2–3 micrometers thick have been

neg: Friction the magnitude of the friction force is the product of the mass of the object, the acceleration due to gravity, and the coefficient of friction. However, the coefficient of friction is not a function of mass or volume; it depends only on the material. For instance, a large aluminum block has the same coefficient of friction as a small aluminum block. However, the magnitude of the friction force itself depends on the normal force, and hence on the mass of the block. If an object is on a level surface and the force tending to cause it to slide is

neg: Darcy–Weisbach equation the fluid are known, as are the diameter of the pipe and its roughness height . If as well the head loss per unit length is a known quantity, then the friction factor can be calculated directly from the chosen fitting function. Solving the Darcy–Weisbach equation for , we can now express : Expressing the roughness Reynolds number , we have the two parameters needed to substitute into the Colebrook–White relation, or any other function, for the friction factor , the flow velocity , and the volumetric flow rate . The Darcy–Weisbach friction factor is 4 times larger than the

neg: Ice any object. However, the significance of this hypothesis is disputed by experiments showing a high coefficient of friction for ice using atomic force microscopy. A third theory is "friction heating", which suggests that friction of the material is the cause of the ice layer melting. However, this theory does not sufficiently explain why ice is slippery when standing still even at below-zero temperatures. A comprehensive theory of ice friction takes into account all the above-mentioned friction mechanisms. This model allows quantitative estimation of the friction coefficient of ice against various materials as a function of temperature and sliding speed. In

neg: Rotating locomotion in living systems a wheel. In addition, large animals cannot produce high accelerations, as inertia increases rapidly with body size. Reducing friction is vital for minimizing wear on mechanical components and preventing overheating. As the relative speed of the components rises, and as the contact force between them increases, the importance of friction mitigation increases. Various types of bearing and/or lubricant may be used to reduce friction at the interface between two components. In biological joints such as the human knee, friction is reduced by means of cartilage with a very low friction coefficient, as well as lubricating synovial fluid, which has very

neg: Differential inclusion the slip is zero, the friction force can be "any" force in the correct plane with magnitude smaller than or equal to "μN" Thus, writing the friction force as a function of position and velocity leads to a set-valued function. Existence theory usually assumes that "F"("t", "x") is an upper hemicontinuous function of "x", measurable in "t", and that "F"("t", "x") is a closed, convex set for all "t" and "x". Existence of solutions for the initial value problem for a sufficiently small time interval ["t", "t" + "ε"), "ε" > 0 then follows. Global existence can be shown provided

neg: Friction powdery solids such as graphite and talc; acoustic lubrication actually uses sound as a lubricant. Another way to reduce friction between two parts is to superimpose micro-scale vibration to one of the parts. This can be sinusoidal vibration as used in ultrasound-assisted cutting or vibration noise, known as dither. According to the law of conservation of energy, no energy is destroyed due to friction, though it may be lost to the system of concern. Energy is transformed from other forms into thermal energy. A sliding hockey puck comes to rest because friction converts its kinetic energy into heat which raises

neg: Skidder small operations continue to use horses. In other places, steel "arches" were used behind the crawlers. Similar in function to the slip-tongue wheels, arches were used to reduce friction by raising up one end of the load, which was dangled from a cable which in turn ran down the back of the arch, & was raised or lowered by the crawler's winch. Another piece similar to the arch was the "bummer", which was simply a small trailer to be towed behind a crawler, on top of which one end of the log load would rest. The early mechanical skidders were

neg: Sulfidation attributed to a layer of chromium oxide that forms due to oxidation of the chromium found in the alloy. The process of liquid sulfidation has also been used in the manufacturing of diamond-like carbon films. These films are generally used to coat surfaces to reduce the wear due to friction. The inclusion of sulfidation in the process has been shown to reduce the friction coefficient of the dlc film. Sulfidation Sulfidation is a process of installing sulfide ions in a material or molecule. The process is widely used to convert oxides to sulfides but is also related to corrosion and

neg: Momentum curtain Momentum curtain Discovered by British engineer Christopher Cockerell, the momentum curtain is a unique and efficient way to reduce friction between a vehicle and its surface of travel, be it water or land, by levitating the vehicle above this surface via a cushion of air. It is this principle of levitation upon which a hovercraft is based, and Christopher Cockerell set about applying his momentum curtain theory to hovercraft to increase their abilities in overcoming friction in travel. Levitating a vehicle above the ground/water to reduce its drag was not a new concept. John Thornycroft, in 1877, discovered that trapping

neg: Ship can lead to excessive pitching and rolling, and eventually capsizing and sinking. The advance of a vessel through water is resisted by the water. This resistance can be broken down into several components, the main ones being the friction of the water on the hull and wave making resistance. To reduce resistance and therefore increase the speed for a given power, it is necessary to reduce the wetted surface and use submerged hull shapes that produce low amplitude waves. To do so, high-speed vessels are often more slender, with fewer or smaller appendages. The friction of the water is also

neg: Kawasaki KX250F a titanium coating to reduce friction, and a few chassis changes which help improve cornering and create an overall slimmer feel. In 2011, Kawasaki added two new major features. The first was a digital fuel injection (DFI) system. This system was similar to the one found on the more powerful KX450F. It greatly improved engine response time and reduced hesitation when landing after a jump. The second addition was Showa's separate function fork (SFF). These new forks lowered weight, improved performance, and allowed for easier adjustability. In 2012, a second fuel injector was added increasing horsepower over the 2011 model.

neg: Friction modifier and pumping losses. However, this means that an increased number of components operate under boundary lubrication conditions. This has led to a resurgence in interest in friction modifier additives, particularly OFMs. For example, recent tribology experiments and molecular dynamics simulations have given new insights into their behaviour under boundary lubrication conditions. Friction modifier Friction modifiers are added to lubricants in order to reduce friction and wear in machine components. They are particularly important in the boundary lubrication regime, where they can prevent solid surfaces from coming into direct contact, substantially reducing friction and wear. Several classes of friction modifier additives

neg: Friction of distance Friction of distance The concept of friction of distance is based on the notion that distance usually requires some amount of effort, energy, time, and/or other resources to overcome. Because of this "friction", spatial interactions, especially transport and the particular case of human migration, will tend to take place more often over shorter distances; amount and intensity of interaction will decay with distance. Regardless of physical friction, the various costs are metaphorically assumed to correspond to forces that impede movements. Friction, be it physical or metaphorical, may be a continuous, smooth function or may contain jumps; it may be constant,

neg: Greater trochanteric pain syndrome There are numerous case reports in which surgery has relieved GTPS, but its effectiveness is not documented in clinical trials. Greater trochanteric pain syndrome Greater trochanteric pain syndrome (GTPS), also known as trochanteric bursitis, is inflammation of the trochanteric bursa, a part of the hip. This bursa is at the top, outer side of the femur, between the insertion of the gluteus medius and gluteus minimus muscles into the greater trochanter of the femur and the femoral shaft. It has the function, in common with other bursae, of working as a shock absorber and as a lubricant for the movement

neg: Friction loss be achieved by using modestly larger ducts. The following table gives flow rate "Q" such that friction loss per unit length Δ"p" / "L" (SI kg / m / s) is 0.082, 0.245, and 0.816, respectively, for a variety of nominal duct sizes. The three values chosen for friction loss correspond to, in US units inch water column per 100 feet, 0.01, .03, and 0.1. Note that, in approximation, for a given value of flow volume, a step up in duct size (say from 100mm to 120mm) will reduce the friction loss by a factor of 3. Note that, for

neg: Sampo (1898 icebreaker) structures were dimensioned beyond Lloyd's Register requirements. The angle of the stem, the first part of the icebreaker to encounter ice and bend it under the weight of the ship, was 24 degrees. Other innovative features included propeller blades that could be replaced underwater by the icebreaker's divers. "Sampo" was powered by two triple-expansion steam engines, one driving a propeller in the stern and the other a second propeller in the bow. The main function of the bow propeller was to reduce friction between the hull and the ice, although the exact details of the icebreaking process were not known

neg: Friction from slipping. Mountain climbers and sailing crews demonstrate a standard knowledge of belt friction when accomplishing basic tasks. Devices such as wheels, ball bearings, roller bearings, and air cushion or other types of fluid bearings can change sliding friction into a much smaller type of rolling friction. Many thermoplastic materials such as nylon, HDPE and PTFE are commonly used in low friction bearings. They are especially useful because the coefficient of friction falls with increasing imposed load. For improved wear resistance, very high molecular weight grades are usually specified for heavy duty or critical bearings. A common way to reduce

neg: Nanomaterials are being used in modern and human-safe insulation technologies, in the past they were found in Asbestos-based insulation. As a lubricant additive, nano materials have the ability to reduce friction in moving parts. Worn and corroded parts can also be repaired with self-assembling anisotropic nanoparticles called TriboTEX. Nanomaterials can also be used in three-way-catalyst (TWC) applications. TWC converters have the advantage of controlling the emission of nitrogen oxides (NOx), which are precursors to acid rain and smog. In core-shell structure, nanomaterials form shell as the catalyst support to protect the noble metals such as palladium and rhodium. The primary function

neg: Tarmo (1907 icebreaker) her predecessor. Both "Tarmo" and "Sampo" were served by a crew of 43. "Tarmo" was powered by two triple-expansion steam engines manufactured in Wallsend, one driving a propeller in the stern and the other a second propeller in the bow. The main function of the bow propeller was to reduce friction between the hull and the ice although the exact details of the icebreaking process were not known at that time. The stern engine produced 1,700 ihp at 97 rpm and the bow engine 1,300 ihp at 107 rpm, but for short periods of time they could put out 2,400

neg: Bearing (mechanical) many types of bearings, with varying shape, material, lubrication, principle of operation, and so on. There are at least 6 common types of bearing, each of which operates on different principles: Common motions permitted by bearings are: Reducing friction in bearings is often important for efficiency, to reduce wear and to facilitate extended use at high speeds and to avoid overheating and premature failure of the bearing. Essentially, a bearing can reduce friction by virtue of its shape, by its material, or by introducing and containing a fluid between surfaces or by separating the surfaces with an electromagnetic field. Combinations

neg: Personal lubricant Personal lubricant Personal lubricants (colloquially termed lube) are specialized lubricants used during human sexual acts such as intercourse and masturbation to reduce friction to or between the penis and vagina, anus or other body parts or applied to sex toys to reduce friction or to ease penetration. Surgical or medical lubricants or gels, which are similar to personal lubricants but not usually referred to or labelled as "personal" lubricants, may be used for medical purposes such as speculum insertion or introduction of a catheter. The primary difference between personal and surgical lubricants is that surgical lubricants are thicker, sterile gels,

neg: Shoulder joint can sometimes allow the shoulder to dislocate. The long head of the biceps brachii muscle travels inside the capsule from its attachment to the supraglenoid tubercle of the scapula. Because the tendon of the long head of the biceps brachii is inside the capsule, it requires a tendon sheath to minimize friction. A number of small fluid-filled sacs known as synovial bursae are located around the capsule to aid mobility: The supra-acromial bursa does not normally communicate with the shoulder joint. The shoulder joint is a muscle-dependent joint as it lacks strong ligaments. The primary stabilizers of the shoulder include

neg: Friction or an ideal fluid which offers no resistance to shearing and so is not viscous. Lubricated friction is a case of fluid friction where a fluid separates two solid surfaces. Lubrication is a technique employed to reduce wear of one or both surfaces in close proximity moving relative to each another by interposing a substance called a lubricant between the surfaces. In most cases the applied load is carried by pressure generated within the fluid due to the frictional viscous resistance to motion of the lubricating fluid between the surfaces. Adequate lubrication allows smooth continuous operation of equipment, with only

neg: Seismometer and angle and size of sheet is adjusted until the damping is "critical", that is, almost having oscillation. The hinge is very low friction, often torsion wires, so the only friction is the internal friction of the wire. Small seismographs with low proof masses are placed in a vacuum to reduce disturbances from air currents. Zollner described torsionally suspended horizontal pendulums as early as 1869, but developed them for gravimetry rather than seismometry. Early seismometers had an arrangement of levers on jeweled bearings, to scratch smoked glass or paper. Later, mirrors reflected a light beam to a direct-recording plate or

neg: Lubricant hose, and wire and cable industries are the largest consumers of anti-tack products but virtually every industry uses some form of anti-sticking agent. Anti-sticking agents differ from "lubricants" in that they are designed to reduce the inherently adhesive qualities of a given compound while lubricants are designed to reduce friction between any two surfaces. Lubricants are typically used to separate moving parts in a system. This separation has the benefit of reducing friction, wear and surface fatigue, together with reduced heat generation, operating noise and vibrations. Lubricants achieve this in several ways. The most common is by forming a physical

neg: Rotation around a fixed axis there is very little friction. For a fan, the motor applies a torque to compensate for friction. Similar to the fan, equipment found in the mass production manufacturing industry demonstrate rotation around a fixed axis effectively. For example, a multi-spindle lathe is used to rotate the material on its axis to effectively increase production of cutting, deformation and turning. The angle of rotation is a linear function of time, which modulo 360° is a periodic function. An example of this is the two-body problem with circular orbits. Internal tensile stress provides the centripetal force that keeps a spinning object together.

neg: Tribology the desired variables. Another widely used process is the ring compression test. A flat ring of the material to be studied is plastically deformed by means of a press, if the deformation is an expansion in both the inner and the inner circle, then there will be low or zero friction coefficients. Otherwise for a deformation that expands only in the inner circle there will be increasing friction coefficients. To reduce friction between surfaces and keep wear under control, materials called lubricants are used. Unlike what you might think, these are not just oils or fats, but any fluid material

neg: NACA Report No. 108 from under 5:1 to over 8:1. The data taken on the tests were exceptionally complete, including many pressures and temperatures, besides the brake and friction torques, rates of fuel and air consumption, the jacket and exhaust heat losses. With the Liberty engine, operating at 500 to 2,000 rpm and with the Hispano-Suiza 300 hp operating at 1,400 to 2,200, it was found that the friction torque increases approximately as a linear function of engine speed at a given air density, and approximately as a linear function of density at a constant speed. This means that the friction horsepower increases approximately

neg: Floating arm trebuchet efficiency. Friction when the counterweight is dropping down to the glide strike can be reduced by using silicone grease or a thin film of plastic on the drop channel. Friction of the wheel on the arm axle against the glide track should be managed in a similar way. To reduce friction of the sling on the launch track, the track should have a smooth surface. The floating arm trebuchet loses the range advantage over regular trebuchet at very large scales, because the difficulty in construction of the drop channel and axle increases with size. A regular trebuchet is a better

neg: Trucker's hitch to 400 lb and the tension in the two lines going to the lower pulley will not change. Theoretical considerations aside, in real world use the mechanical advantage of the trucker's hitch is significantly less than the ideal case due to the effects of friction. Friction has been reported to reduce the mechanical advantage from 3 to 1, to well less than 2 to 1 in many cases. One advantage of the friction within the trucker's hitch, compared to a hypothetical pulley-based system, is that it allows the hitch to be held taut with less force while the working end

neg: Ski wax with the snow and are negligible on a firm surface. Lubrication, capillary attraction and contamination are issues for the ski bottom and the wax that is applied to reduce sliding friction or achieve adequate grip. Typically, a sliding ski melts a thin and transitory film of lubricating layer of water, caused by the heat of friction between the ski and the snow in its passing. Colbeck suggests that the optimum water film thickness is in the range between 4 and 12 "μ"m. However, the heat generated by friction can be lost by conduction to a cold ski, thereby diminishing the

neg: Angle of repose As a result, data from different labs are not always comparable. One method is the triaxial shear test, another is the direct shear test. If the coefficient of static friction is known of a material, then a good approximation of the angle of repose can be made with the following function. This function is somewhat accurate for piles where individual objects in the pile are minuscule and piled in random order. where, "μ" is the coefficient of static friction, and "θ" is the angle of repose. The measured angle of repose may vary with the method used. This method is

neg: Parasitic drag aircraft, a decrease in length (chord) of the wings will reduce "induced" drag though, if not the friction drag. The skin friction coefficient, formula_5, is defined by where formula_7 is the local wall shear stress, and q is the free-stream dynamic pressure. There are two ways...if not the friction drag., For boundary layers without a pressure gradient in the x direction, it is related to the momentum thickness as For comparison, the turbulent empirical relation known as the 1/7 Power Law (derived by Theodore von Kármán) is: where formula_10 is the Reynolds number. Parasitic drag Parasitic drag is drag that

neg: Machine chariot. A wheel uses the law of the lever to reduce the force needed to overcome friction when pulling a load. To see this notice that the friction associated with pulling a load on the ground is approximately the same as the friction in a simple bearing that supports the load on the axle of a wheel. However, the wheel forms a lever that magnifies the pulling force so that it overcomes the frictional resistance in the bearing. The classification of simple machines to provide a strategy for the design of new machines was developed by Franz Reuleaux, who collected

neg: NACA Report No. 108 as a percent of the heat accounted for, is practically the same as the theoretical rejection of heat computed for the same compression ratio. An empirical and approximate statement, applicable to the speed and density ranges herein covered, is that the friction torque (m. e. p.) increases as a linear function of speed at Q constant, air density, and as a linear function of air density at a constant speed. This applies to both the Liberty 12-cylinder and the Hispano-Suiza 8-cylinder engines. The true relations of friction torque, engine speed, and air density are much more complex and cannot be

neg: Geostrophic wind Flow of ocean water is also largely geostrophic. Just as multiple weather balloons that measure pressure as a function of height in the atmosphere are used to map the atmospheric pressure field and infer the geostrophic wind, measurements of density as a function of depth in the ocean are used to infer geostrophic currents. Satellite altimeters are also used to measure sea surface height anomaly, which permits a calculation of the geostrophic current at the surface. The effect of friction, between the air and the land, breaks the geostrophic balance. Friction slows the flow, lessening the effect of the Coriolis

neg: Bearing (mechanical) consistent, controlled friction as well as durability whilst the metal backing ensures the composite bearing is robust and capable of withstanding high loads and stresses throughout its long life. Its design also makes it lightweight-one tenth the weight of a traditional rolling element bearing. There are many different types of bearings. Newer versions of more enabling designs are in development being tested, in which will reduce friction, increase bearing load, increase momentum build-up, and speed. Bearing (mechanical) A bearing is a machine element that constrains relative motion to only the desired motion, and reduces friction between moving parts. The design

neg: Pasta processing grooves in the cylinder reduce the friction and improves the movement of the dough. Both the worm and the cylinder are made of stainless steel, but the worm has a Teflon coating to decrease friction. The temperature of the dough should remain between 40-45°C. If the temperature exceeds the 50°C the gluten network would be damaged which has a negative effect on the quality of pasta. Since extra heat is generated by pressure and friction, there are water jackets around the cylinder and head. Large amount of water with high speed and temperature of 38-40°C is circulated in jackets. The

neg: Blister A lubricant, typically talcum powder, can be used to reduce friction between skin and apparel in the short term. People put talcum powder inside gloves or shoes for this purpose, although this type of lubricant will increase the friction in the long term, as it absorbs moisture. Increased friction makes blisters more likely. Sunscreen and protective clothing should also be used during the hottest part of the day to avoid blisters from sunburn. Avoiding sunlight during midday is the best way to avoid blisters from sunburn. Protective gloves should be worn when handling detergents, cleaning products, solvents and other chemicals.

neg: MSV Botnica ramming. To improve the ship's maneuverability in ice her hull is wider at the bow than in the stern. These "reamers" increase the width of the ice channel and reduce friction between the hull and ice. In addition the hull has an explosion-welded stainless steel ice belt that reduces friction and protects the steel plates from abrasion at the waterline. The hull is coated with low-friction Inerta 160 epoxy paint. For offshore construction projects "Botnica" was built with a 160-ton Hydralift ASA crane, but it was replaced in 2010 with a 150-ton MacGregor crane with active heave compensation. The vessel

neg: Blister used for competitive rowing are known for causing frequent blisters on the hands of oarsmen. Weightlifters are also prone to blisters as are gymnasts from the friction developed by the rubbing against the bars. To further reduce the occurrence one can tape the hands, and there are also a number of products on the market that claim to reduce the occurrence of blisters. These are all intended to be worn as a liner underneath a glove. The majority of these offerings simply add padding and create a layer that reduces the coefficient of friction between the skin and the glove.

neg: Tribometer Tribometer A tribometer is an instrument that measures tribological quantities, such as coefficient of friction, friction force, and wear volume, between two surfaces in contact. It was invented by the 18th century Dutch scientist Musschenbroek A tribotester is the general name given to a machine or device used to perform tests and simulations of wear, friction and lubrication which are the subject of the study of tribology. Often tribotesters are extremely specific in their function and are fabricated by manufacturers who desire to test and analyze the long-term performance of their products. An example is that of orthopedic implant manufactures

neg: Governor of Bursa Governor of Bursa The Governor of Bursa (Turkish: "Bursa Valiliği") is the bureaucratic state official responsible for both national government and state affairs in the Province of Bursa. Similar to the Governors of the 80 other Provinces of Turkey, the Governor of Bursa is appointed by the Government of Turkey and is responsible for the implementation of government legislation within Bursa. The Governor is also the most senior commander of both the Bursa provincial police force and the Bursa Gendarmerie. The Governor of Bursa is appointed by the President of Turkey, who confirms the appointment after recommendation from the Turkish

neg: Snake scale patterns have been thought to have influenced early art. The use of snake-skin in manufacture of purses, apparel and other articles led to large-scale killing of snakes, giving rise to advocacy for use of artificial snake-skin. Snake scales are also to be found as motifs in fiction, art and films. The scales of a snake primarily serve to reduce friction as it moves, since friction is the major source of energy loss in snake locomotion. The ventral (or belly) scales, which are large and oblong, are especially low-friction, and some arboreal species can use the edges to grip branches. Snake

neg: Darcy friction factor formulae the Lambert W-function The equation was found to match the Colebrook–White equation within 3.15%. Early approximations for smooth pipes by Paul Richard Heinrich Blasius in terms of the Moody friction factor are given in one article of 1913: Johann Nikuradse in 1932 proposed that this corresponds to a power law correlation for the fluid velocity profile. Mishra and Gupta in 1979 proposed a correction for curved or helically coiled tubes, taking into account the equivalent curve radius, R: with, where "f" is a function of: valid for: The following table lists historical approximations to the Colebrook–White relation for pressure-driven flow.

neg: Fluid bearing as bearing friction otherwise would. Better seals can reduce leak rates and pumping power, but may increase friction. Hydrodynamic bearings rely on bearing motion to suck fluid into the bearing, and may have high friction and short life at speeds lower than design, or during starts and stops. An external pump or secondary bearing may be used for startup and shutdown to prevent damage to the hydrodynamic bearing. A secondary bearing may have high friction and short operating life, but good overall service life if bearing starts and stops are infrequent. "Hydrodynamic" (HD) "lubrication", also known as "fluid film lubrication"

neg: Subaru EJ engine The pistons were coated with molybdenum to reduce friction. The thin coating reduces moving friction and reduces cylinder wall scuffing. The piston skirt was reshaped and the piston weight was reduced by approximately . Compression ratio was increased to 9.7:1 by reshaping the piston crown. This eliminates the clearance that was available between the piston at TDC and the fully opened valve. Piston pin offset has been changed to . Piston to cylinder wall clearance has been reduced by increasing the piston diameter. Another source of high engine friction is the valve train. Hydraulic lash adjusters (HLAs) are always in

neg: Darcy–Weisbach equation as an analytic function of through the use of the Lambert function: In this flow regime, many small vortices are responsible for the transfer of momentum between the bulk of the fluid to the pipe wall. As the friction Reynolds number increases, the profile of the fluid velocity approaches the wall asymptotically, thereby transferring more momentum to the pipe wall, as modeled in Blasius boundary layer theory. When the pipe surface's roughness height is significant (typically at high Reynolds number), the friction factor departs from the smooth pipe curve, ultimately approaching an asymptotic value ("rough pipe" regime). In this regime,

neg: Road texture Microtexture has wavelengths shorter than 0.5 mm. It relates to the surface of the binder, of the aggregate, and of contaminants such as rubber deposits from tires. The mix of the road material contributes to dry road surface friction. Typically, road agencies do not monitor mix directly, but indirectly by brake friction tests. However, friction also depends on other surface properties, such as macro-texture. Macrotexture (MaTx) is partly a desired property and partly an undesired property. Short MaTx waves, about 5 mm, act as acoustical pores and reduce tyre/road noise. On the other hand, long wave MaTx increase noise. MaTx

neg: Yaw bearing such as POM or PA. To reduce friction, wear, and avoid stick-slip effects (often present in such high friction slow moving systems), lubrication is often introduced. This solution generally solves the gliding issues, but introduces more components to the systems and increases the general complication (e.g., difficult maintenance procedures for removal of used lubricant). Some wind turbine manufacturers now use self lubricating gliding elements instead of a central lubrication system. These gliding elements are manufactured from low friction materials or composites (e.t.g Teflon) that allow reliable operation of dry (non-lubricated) gliding yaw systems. Despite the fact that the gliding yaw

neg: Honda RVF750 RC45 oil control ring. It used low friction rings and a molybdenum disulphide coating on smaller piston skirts to reduce friction. One huge change in engine architecture was the change from centre gear drive mechanism to crank/camshaft drive, which was located on the end of the crankshaft (another NR750 follow on). This reduced the number of engine crankshaft bearings by one and camshaft bearings by four with an associated reduction in friction. This overall reduction in friction also allowed the engine to see the higher engine revolutions Honda desired without losing horsepower. The RC45 also followed the RC30 in using titanium

neg: Sediment Profile Imagery adjacent grains (both static and dynamic). The wedge does displacement work by using less force at the cost of increasing the distance the grain must travel. In order to reduce the size of an SPI device it makes sense to reduce the amount of work required to displace sediment for a given imaging area. Being in an aquatic environment gives the first advantage to reducing work. By increasing the water content of sediments, both static and dynamic coefficients of friction from grain-on-grain interactions are greatly reduced. At these large physical scales, viscosity interactions are very small compared to friction. Therefore,

neg: Icebreaker and protects the ship's hull from corrosion. Auxiliary systems such as powerful water deluges and air bubbling systems are used to reduce friction by forming a lubricating layer between the hull and the ice. Pumping water between tanks on both sides of the vessel results in continuous rolling that reduces friction and makes progress through the ice easier. Experimental bow designs such as the flat Thyssen-Waas bow and a cylindrical bow have been tried over the years to further reduce the ice resistance and create an ice-free channel. Icebreakers and other ships operating in ice-filled waters require additional structural strengthening

neg: Synovial bursa an adventitious bursa develops under it. Examples are Students' elbow and bunion. Infection or irritation of a bursa leads to bursitis (inflammation of a bursa). The general term for disease of bursae is "bursopathy." is Medieval Latin for "purse", so named for the resemblance of an anatomical bursa to a purse. "Bursae" or "bursas" is its plural form. Imaging of the Bursae via Pub Med https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3177464/ Synovial bursa A synovial bursa (plural bursae or bursas) is a small fluid-filled sac lined by synovial membrane with an inner capillary layer of viscous synovial fluid (similar in consistency to that of a

neg: Calvin Blignault in-process monitoring of the temperature and the three dimensional forces within the rotating tool. He recommended that FSW users and researchers consider the use of dedicated friction stir welding monitoring equipment for in-process verification of weld quality. Researchers can also analyse process response data to reduce the empiricism associated with initial tool and parameter development. In May 2008 he published an article on “Friction Stir Welding for the Fabrication of Aluminium Rolling Stock”. Friction stir welded structures are revolutionising the way in which trains, metro cars and trams are built. Friction stir welding has been widely recognised for its ability

neg: Honda Civic (fifth generation) as reduced trim and molding, aluminum alloy wheels, only small drum brakes on the rear wheels, lightweight 155/80 R13 tires, and a gas tank with only an 8 gallon capacity versus the standard civic 10 gallon, and through a 1.5 L (D15Z1) VTEC-E engine yielding 48/55 mpg (city/hwy) ["revised to 2008 EPA rating: 39/49 mpg city/hwy"] or 44/51 mpg (city/hwy) ["revised to 2008 EPA rating: 36/46 mpg city/hwy"]. The D15Z1 engine's efficiency was enhanced by placing cam followers(bearings) at every cam lobe, to reduce friction, the use of only two piston rings per cylinder, to reduce friction, and the ability

neg: Fluid bearing of friction in a fluid bearing is the viscosity of the fluid. Hydrostatic gas bearings are among the lowest friction bearings. However, lower fluid viscosity also typically means fluid leaks faster from the bearing surfaces, thus requiring increased power for pumps or friction from seals. When a roller or ball is heavily loaded, fluid bearings have clearances that change less under load (are "stiffer") than mechanical bearings. It might seem that bearing stiffness, as with maximum design load, would be a simple function of average fluid pressure and the bearing surface area. In practice, when bearing surfaces are pressed together,

neg: Iliopectineal bursa iliopectineal bursa is partly separated by a septum into two cavities. Here the tendon of the psoas major muscle passes over the medial chamber and the tendon of the iliacus muscle runs over the lateral chamber. Inflammation of the iliopectineal bursa is called iliopectineal bursitis or iliopsoas bursitis. Iliopectineal bursa The iliopectineal bursa or the iliopsoas bursa is a large synovial bursa that separates the external surface of the hip joint capsule from the normally just the tendon of the iliopsoas muscle. The most proximal of part the iliopectineal bursa lies on the iliopubic eminence of the superior pubic ramus.

neg: FTSE Bursa Malaysia Index FTSE Bursa Malaysia Index The FTSE Bursa Malaysia Index is a comprehensive range of real-time indices, which cover all eligible companies listed on the Bursa Malaysia Main Board which was introduced to Bursa Malaysia's investors in 2006. The indices are to measure the performance of the major capital segments of the Malaysian market, The FTSE Bursa Malaysia Index was launched on 26 June 2006 except for FTSE Bursa Malaysia Hijrah Shariah Index and FTSE Bursa Malaysia EMAS Shariah Index which were launched on 22 January 2007 and 21 May 2007 respectively. The launch of the FTSE Bursa Malaysia Hijrah Shariah

neg: Pseudo-Boolean function we can either solve P or reduce the number of variables to formula_24. Let formula_25 be the degree of the above multi-linear polynomial for formula_16. Then proved that in polynomial time we can either solve P or reduce the number of variables to formula_27. Pseudo-Boolean function In mathematics and optimization, a pseudo-Boolean function is a function of the form where B = {0, 1} is a "Boolean domain" and "n" is a nonnegative integer called the arity of the function. A Boolean function is then a special case, where the values are also restricted to 0,1. Any pseudo-Boolean function can

neg: Prepatellar bursa Prepatellar bursa The prepatellar bursa is a frontal bursa of the knee joint. It is a superficial bursa with a thin synovial lining located between the skin and the patella. Prepatellar bursitis, also known as housemaid's knee, is a common cause of swelling and pain above the patella (kneecap), and is due to inflammation of the prepatellar bursa. It is common in people who frequently kneel, such as roofers, plumbers, carpet layers, and gardeners. It is also common in wrestlers due to the repeated impact on the knee when shooting. Symptoms include knee pain, swelling, redness and inability to flex

neg: Dry lubricant °F). The low-friction characteristics of most dry lubricants are attributed to a layered structure on the molecular level with weak bonding between layers. Such layers are able to slide relative to each other with minimal applied force, thus giving them their low friction properties. However, a layered crystal structure alone is not necessarily sufficient for lubrication. In fact, there are some solids with non-lamellar structures that function well as dry lubricants in some applications. These include certain soft metals (indium, lead, silver, tin), polytetrafluroethylene, some solid oxides, rare-earth fluorides, and even diamond. Limited interest has been shown in low friction

neg: 2009–11 Toyota vehicle recalls force versus pedal position transfer function. Put more simply, once the pedal was set at a specific position, the friction would help keep the pedal at this setting. This made it easier for the driver to maintain a pedal position. For example, if the driver's foot is slightly jostled by a bump in road, the accelerator pedal would tend to stay at its setting. While these old purely mechanical designs did have some friction, the return spring force was always designed to overcome this friction with a considerable safety margin. The return spring force ensured that throttle returned to zero

neg: Ski wax that factors other than wax are much more important in reducing friction on cross-country skate skis—the curvature of the ski and snow conditions. Glide wax can be applied to alpine skis, snowboards, skate skis, classic skis, back-country skis, and touring skis. Traditional waxes comprise solid hydrocarbons. High-performance "fluorocarbon" waxes also contain fluorine which substitute some fraction of the hydrogen atoms in the hydrocarbons with fluorine atoms to achieve lower coefficients of friction and high water-repellency than the pure hydrocarbon wax can achieve. Wax is adjusted for hardness to minimize sliding friction as a function of snow properties, which include the

neg: DC injection braking DC injection braking DC injection braking is a method of slowing AC electric motors. A DC voltage is injected into the winding of the AC motor after the AC voltage is disconnected, providing braking force to the rotor. When power is disconnected from the motor, the rotor spins freely until friction slows it to a stop. Large rotors and loads with a high moment of inertia may take a significant amount of time to stop through inherent friction alone. To reduce downtime, or possibly as an emergency safety feature, DC injection braking can be used to quickly stop the rotor.

neg: Iliopectineal bursa Iliopectineal bursa The iliopectineal bursa or the iliopsoas bursa is a large synovial bursa that separates the external surface of the hip joint capsule from the normally just the tendon of the iliopsoas muscle. The most proximal of part the iliopectineal bursa lies on the iliopubic eminence of the superior pubic ramus. The iliopectineal bursa passes across the front of the capsule of the hip joint and extends distally downwards almost as far as to the lesser trochanter. The iliopectineal bursa frequently communicates by a circular aperture with the cavity of the hip joint. In 13% of all cases the

neg: Viscosity index apart to achieve "fluid bearing" conditions is desired. If the lubricant is too viscous, it will require a large amount of energy to move (as in honey); if it is too thin, the surfaces will come in contact and friction will increase. Many lubricant applications require the lubricant to perform across a wide range of conditions, for example, automotive lubricants are required to reduce friction between engine components when the engine is started from cold (relative to the engine's operating temperatures) up to when it is running. The best oils with the highest VI will remain stable and not vary