The researchers had to take these inhibiting forces into account to keep the bots moving and on track, and to prevent them from getting bogged down by static friction, or "stiction," as the researchers call it.
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2007 Reliability issues pertaining to high-power operation are discussed in the limiter section. Fig. 5: (a) [Bottom] Dielectric charging induced beam stiction. (b) [Top] Humidity induced beam stiction.
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In addition to the reduction in vehicle weight, the weight of the spring is partly unsprung mass. The relative sliding movement of the leaves of a multi-leaf steel spring results in stiction-based hysteresis with respect to spring compression. This stiction reduces suspension compliance and can compromise both ride quality and handling. Lacking individual leaves, the mono-leaf spring avoids stiction.
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In general, CSS technology can be prone to increased stiction (the tendency for the heads to stick to the platter surface), e.g. as a consequence of increased humidity. Excessive stiction can cause physical damage to the platter and slider or spindle motor.
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CO2 displaces the rinsing fluid and is heated past the supercritical point. As the chamber pressure is slowly released the CO2 sublimates thereby preventing stiction.
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In situations where two surfaces with areas below the micrometer scale come into close proximity (as in an accelerometer), they may adhere together. At this scale, electrostatic and/or Van der Waals and hydrogen bonding forces become significant. The phenomenon of two such surfaces being adhered together in this manner is also called stiction. Stiction may be related to hydrogen bonding or residual contamination.
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Microelectromechanical systems (MEMS) are used in a number of different applications and have become increasingly more prevalent in nanoscale applications. However, due to their small size they run into problems with stiction, caused by capillary condensation among other forces. Intense research in the area of Microelectromechanical systems has been focused on finding ways to reduce stiction in the fabrication of Microelectromechanical systems and when they are being used. Srinivasan et al.
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Stiction is the static friction that needs to be overcome to enable relative motion of stationary objects in contact. The term is a portmanteau of the words static and friction, perhaps also influenced by the verb stick. Any solid objects pressing against each other (but not sliding) will require some threshold of force parallel to the surface of contact in order to overcome static cohesion. Stiction is a threshold, not a continuous force.
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Vapor etching overcomes stiction because no liquids are used during the etch process. Commonly, hydrogen fluoride and xenon difluorides are used to etch silicon dioxide and silicon sacrificial layers respectively.
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This issue has often led to linkages being redesigned from sliding to purely pivoted structures, just to avoid problems with stiction. An example is the Chapman strut, a suspension linkage.
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Stiction refers to the characteristic of stop and start type motion as a force overcomes static friction and causes a part to accelerate under dynamic friction, but the force cannot keep up with the speed of the moving part so the part tends to stop again until the force catches up, and it happens repeatedly. Stiction is a problem for the design and materials science of many moving linkages. This is particularly the case for linear sliding joints, rather than rotating pivots. Owing to simple geometry, the moving distance of a sliding joint in two comparable linkages is longer than the circumferential travel of a pivoting bearing, thus the forces involved (for equivalent work) are lower and stiction forces become proportionally more significant.
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Stiction is the inability of the beam to release after removal of the drive voltage. A high contact pressure assures a low-ohmic contact or alleviates dielectric charging induced beam stiction. Commercially available ohmic cantilever RF MEMS switches and capacitive fixed-fixed beam RF MEMS switches have demonstrated lifetimes in excess of 100 billion cycles at 100 mW of RF input power.H. S. Newman, J. L. Ebel, D. Judy, and J. Maciel: "Lifetime Measurements on a High-Reliability RF MEMS Contact Switch," IEEE Microwave Wireless Compon. Lett.
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Stiction or adhesion between the substrate (usually silicon based) and the microstructure occurs during the isotropic wet etching of the sacrificial layer. The capillary forces due to the surface tension of the liquid between the microstructure and substrate during drying of the wet etchant cause the two surfaces to adhere together. Separating the two surfaces is often complicated due to the fragile nature of the microstructure. Stiction is often circumvented by the use of a sublimating fluid (often supercritical CO2, which has extremely low surface tension) drying process where the liquid phase is bypassed.
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Contact interface degradation poses a reliability issue for ohmic cantilever RF MEMS switches, whereas dielectric charging beam stiction,Samuel Mellé, Student Member IEEE, David De Conto, David Dubuc, Member IEEE, Katia Grenier, Member IEEE, Olivier Vendier, Jean-Luc Muraro, Jean-Louis Cazaux, Senior Member IEEE, and Robert Plana Member IEEE : Reliability Modeling of Capacitive RF MEMS, IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 53, NO. 11, NOVEMBER 2005 as shown in Fig. 5(a), and humidity induced beam stiction, as shown in Fig. 5(b), pose a reliability issue for capacitive fixed-fixed beam RF MEMS switches.
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This allows the broadly defined notions of galling, fretting, sticking, stiction and adhesion to overlap in some instances. For example, it is possible for a joint to be the result of both cold (or "vacuum") welding and galling (and/or fretting and/or impact). Galling and cold welding, therefore, are not mutually exclusive.
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The damping rate for frictional dampers has less than ideal behaviour for car suspension. An ideal suspension would offer more damping to greater suspension forces, with less damping at low speeds for a smoother ride. Frictional dampers though had a mostly constant rate. This was even greater when stationary, owing to stiction between stationary plates.
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Some objects are in resting contact, that is, in collision, but neither bouncing off, nor interpenetrating, such as a vase resting on a table. In all cases, resting contact requires special treatment: If two objects collide (a posteriori) or slide (a priori) and their relative motion is below a threshold, friction becomes stiction and both objects are arranged in the same branch of the scene graph.
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The rear shock was now a Showa unit with Showa forks at the front, making use of Titanium-Nitride (TiN) coating on the fork stanchions to "reduce stiction", which also gave it a gold coloring. The engine was the same as the 748E. The top of the range model was now the 748R, Ducati's racing homologation model produced only in very limited numbers. This engine was again a derivative of the SPS model but with more tuning.
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Maboudian's research is in the development of new applications of micro- and nano-technology, especially surface chemistry and adhesion. Her early research studied the use of self-assembled monolayers as anti-stiction coatings for MEMS (microelectromechanical) structures. Since then, her work has broadened to other aspects of materials, surfaces, and interfaces, including chemical sensing, gecko-inspired adhesives, and supercapacitors. In 2019, she was named a Bakar Fellow, a UC Berkeley fellowship for projects with commercial promise.
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The wet etching of SiO2 in buffered hydrogen fluoride solutions is a common and well understood process in micro fabrication. In 1966, Holmes and Snell found that SiO2 can be etched in hydrogen fluoride vapor. Initially the interest in this finding was low, because wet etch processes have higher etch rates and did not require sophisticated equipment. During the advent of MEMS technology and the consecutive reduction of size however, stiction started to have a significant impact on the production yields.
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Leaf springs can serve locating and to some extent damping as well as springing functions. While the interleaf friction provides a damping action, it is not well controlled and results in stiction in the motion of the suspension. For this reason, some manufacturers have used mono-leaf springs. A leaf spring can either be attached directly to the frame at both ends or attached directly at one end, usually the front, with the other end attached through a shackle, a short swinging arm.
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The RC8 R was delivered to the United States in 2010 as a 2011 model with more track-oriented features than the standard RC8. Engine displacement increased to with a higher compression ratio of 13.5:1. It has titanium intake valves and a low-friction diamond-like carbon (DLC) treatment on its camshafts' finger followers. The RC8 R's WP suspension includes a 43 mm inverted fork at the front end, with a titanium-aluminum-nitride low-stiction coating on its sliders.
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As with the first, a pause at halfway was performed to allow the arrays to heat up in the sun. While some stiction was seen, once the final extension began all the slats flattened out, and the arrays were fully deployed at 17:17 UTC. The addition of the final set of solar panels brings the station's power output to 120 kilowatts, and doubles the scientific power to 30 kilowatts. The station's surface area of the arrays is just under one acre, or 38,400 square feet.
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Many PID loops control a mechanical device (for example, a valve). Mechanical maintenance can be a major cost and wear leads to control degradation in the form of either stiction or backlash in the mechanical response to an input signal. The rate of mechanical wear is mainly a function of how often a device is activated to make a change. Where wear is a significant concern, the PID loop may have an output deadband to reduce the frequency of activation of the output (valve).
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In the field of precision engineering (especially high- precision motion control), flexures have several key advantages. High precision alignment tasks might not be possible when friction or stiction are present. Additionally, conventional bearings or linear slides often exhibit positioning hysteresis due to backlash and friction. Flexures are able to achieve much lower resolution limits (in some cases measured in the nanometer scale), because they depend on bending and/or torsion of flexible elements, rather than surface interaction of many parts (as with a ball bearing).
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Load/unload technology relies on the heads being lifted off the platters into a safe location, thus eliminating the risks of wear and stiction altogether. The first HDD RAMAC and most early disk drives used complex mechanisms to load and unload the heads. Modern HDDs use ramp loading, first introduced by Memorex in 1967, to load/unload onto plastic "ramps" near the outer disk edge. Addressing shock robustness, IBM also created a technology for their ThinkPad line of laptop computers called the Active Protection System.
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The friction disk material was usually a wooden disk between the two faces of the steel arms. As for the development of the clutch and brake shoes, the development of these friction materials was in its infancy. Treated leather had been used for clutches and although it offered good friction behaviour, it was prone to stiction when first moving off and also failed when overheated. Asbestos-based friction materials were sometimes used for racing, in an attempt to keep dampers working correctly even when overheating.
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Stiction is also the same threshold at which a rolling object would begin to slide over a surface rather than rolling at the expected rate (and in the case of a wheel, in the expected direction). In this case, it's called "rolling friction" or μr. This is why driver training courses teach that if a car begins to slide sideways, the driver should try to steer in the same direction as the slide with no brakes. It gives the wheels a chance to regain static contact by rolling, which gives the driver some control again.
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Scrape flutter—a high frequency flutter of above 1000 Hz—can sometimes occur from the tape vibrating as it passes over a head, as a result of rapidly interacting stretch in the tape and stiction at the head. It adds a roughness to the sound that is not typical of wow and flutter, and damping devices or heavy rollers are sometimes employed on professional tape machines to prevent it. Scrape flutter measurement requires special techniques, often using a 10 kHz tone. A typical modern cassette recorder may have a wow and flutter specification of 0.08%.
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MEMS and other mechanical switching methods can achieve a relatively low insertion loss (2.5 dB) and an excellent linearity, but are prone to stiction and reliability issues Reconfigurable materials have shown promise for enabling a low-loss beam steering transmitarray. A vanadium dioxide reconfigurable metasurface operating at 100 GHz was presented in using a crossed-slot unit cell. A heating element was used to thermally control the phase shift through each cell. The permittivity of liquid crystal (and hence the phase shift) can be reconfigured by applying a voltage between two parallel conducting plates.
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Air bearings on a drill spindle for printed circuit boards Unlike contact-roller bearings, an air bearing (or air caster) utilises a thin film of pressurized air to provide an exceedingly low friction load-bearing interface between surfaces. The two surfaces don't touch. Being non-contact, air bearings avoid the traditional bearing-related problems of friction, wear, particulates, and lubricant handling, and offer distinct advantages in precision positioning, such as lacking backlash and stiction, as well as in high-speed applications. The fluid film of the bearing is air that flows through the bearing itself to the bearing surface.
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Some causes of failure may be expected in any computer built the same way. If chips are attached to the boards in sockets, rather than soldered on, they may be loose because they expanded from heat whenever the computer was on for a long time, then contracted whenever the computer was turned off. A computer that was used a great deal, and for a long time, may require a new owner to open it up and gently press the chips down before it will run. Another problem sometimes found in old Eagles with hard disks is stiction.
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Resolution will be limited by the mechanical stiction, backlash, and other sources of error between the motor and the end device. Gear reducers may be used to increase resolution of positioning. Step size reduction is an important step motor feature and a fundamental reason for their use in positioning. Example: many modern hybrid step motors are rated such that the travel of every full step (example 1.8 degrees per full step or 200 full steps per revolution) will be within 3% or 5% of the travel of every other full step, as long as the motor is operated within its specified operating ranges.
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Vapor etching refers to a process used in the fabrication of Microelectromechanical systems (MEMS) and Nanoelectromechanical systems (NEMS). Sacrificial layers are isotropically etched using gaseous acids such as Hydrogen fluoride and Xenon difluoride to release the free standing components of the device. Economic advantages and novel technological possibilities result from micron to nano scale size reductions. (MEMS to NEMS) The small dimensions make the use of isotropic wet etch processes traditionally used in mirco fabrication suffer from stiction, the permanent adherence of the free standing structure to the underlying substrate due to the scaling of surface effects occurring during the drying of the acid.
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The advantage of a gas phase reaction over a comparable liquid phase process is the control of moisture from the ambient environment, which often results in cross polymerization of the silane leading to particulates on the treated surface. Often a heated sub- atmospheric vacuum chamber is used to allow precise control of the reactants and water content. Additionally the gas phase process allows for easy treatment of complex parts since the coverage of the reactant is generally diffusion limited. Microelectromechanical Systems (MEMS) sensors often use molecular vapor deposition as a technique to address stiction and other parasitic issues relative to surface-to-surface interactions.
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Acaba used the shuttle's ergometer before the crews began deploying the solar arrays. The S6 truss solar array unfurled. As part of the re-planning for the mission, the crews set to work in the morning deploying the solar wings on the S6 truss. To prepare for the extension of the arrays, the station was maneuvered into a position that allowed constant sunlight to hit the arrays, which allowed them to warm up and prevent what the mission team calls 'stiction', or a sticky friction that happens after the arrays have been in storage for an extended period of time. The unfurling of the arrays started at 15:06 UTC, beginning with the channel 1B array.
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The length of the typical motorcycle fork means that they act as large levers about the headstock requiring the forks, the headstock, and the frame to be very robust adding to the bike's weight. Hub-center steering systems use an arm, or arms, on bearings to allow upward wheel deflection, meaning that there is no stiction, even under braking. Braking forces can be redirected horizontally along these arms, or tie rods, away from the vertical suspension forces, and can even be put to good use to counteract weight shift. Finally, the arms typically form some form of parallelogram which maintains steering geometry over the full range of wheel travel, allowing agility and consistency of steering that forks currently cannot get close to attaining.
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When the engine is shut down at altitude, the core begins to cool, and the stator, including the static interstage static seal (ISS), contracts at a faster rate than the adjacent rotating parts in both the radial and axial direction because of its smaller thermal time constant. The relative rate of cooling of the stator and rotor results in an alignment of the rotating-seal knife edges aft of the normal operating groove in the static seal. If the clearances are tight enough and the relative cooling rates are right, contact can occur between the static and rotating seal elements. The resulting stiction can temporarily prevent the rotor from turning when only the force of ram air is applied to the core.
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Numerous PCM recalibrations, attempts to "detune" the engine, fuel injector stiction (caused by lack of maintenance and proper oil changes) along with several other driveability and quality control problems have plagued the 6.0. The FICM (fuel injection control module) has been a problem, where low voltage in the vehicle's electrical system due to failing batteries or a low-output alternator can cause damage to the FICM. In addition, the placement of the FICM on top of the engine subjects it to varying and extreme temperatures and vibrations causing solder joints and components to fail in early build models; mostly in the power supply itself. The FICM multiplies the voltage in the fuel injector circuit from 12 to 48-50 volts to fire the injectors.
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Ride suffers because the shock absorber has almost the same vertical motion as the wheel, so there is relatively little leverage to break the stiction in the seals. A standard single pivot MacPherson strut also tends to have positive scrub where the center of the steering axis is offset from the center of the front tires, which results in torque steer. Despite these drawbacks, the MacPherson strut setup is still used on some high performance cars, because they tend to have relatively small suspension travel, and so do not see the kinematic problems. Porsche 911 up until the 1989 model year (964) used a similar strut design that does not have coil springs, using torsion bar suspension instead, after that point all Porsche 911s have had front MacPherson struts.
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Blish patent Thompson M1928A1 bolt group with an "H" type Blish-lock piece Thompson Autorifle Model 1923 (top, upright) chambered in 7.62×54mmR and SMG Model of 1921 (bottom, inverted) are both examples of firearms that used the Blish lock The Blish lock is a breech locking mechanism designed by John Bell Blish based upon his assumption that under extreme pressures, certain dissimilar metals would resist movement with a force greater than friction laws would predict. In modern engineering terminology, it is an extreme manifestation of what is now called static friction, or stiction. His locking mechanism was used first in the Thompson submachine gun. Nowadays it is discredited as a useful firearm operating principle, due to its almost nonexistent effects on the operation and functioning of a firearm; because of that, firearms which theoretically employed it operate not by the supposed Blish lock principle, but, in fact, by blowback operation.
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However, the decay rate is not linear: when a disk is younger and has had fewer start-stop cycles, it has a better chance of surviving the next startup than an older, higher-mileage disk (as the head literally drags along the disk's surface until the air bearing is established). For example, the Seagate Barracuda 7200.10 series of desktop hard disk drives are rated to 50,000 start-stop cycles, in other words no failures attributed to the head-platter interface were seen before at least 50,000 start-stop cycles during testing. Around 1995 IBM pioneered a technology where a landing zone on the disk is made by a precision laser process (Laser Zone Texture = LZT) producing an array of smooth nanometer- scale "bumps" in a landing zone, thus vastly improving stiction and wear performance. This technology is still largely in use today, predominantly in desktop and enterprise (3.5-inch) drives.
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A further level of integration of shaft rotations by either electronic means or by mechanical means, such as a Ball-and-disk integrator, can record the displacement or distance traveled, this latter mechanical method being used by early guidance systems prior to the availability of suitable digital computers. In most implementations of the PIGA the gyroscope itself is cantilevered on the end of the pendulum arm to act as the pendulous mass itself. Up to three such instruments may be required for each dimension of an INS with the three accelerometers mounted orthogonally generally on a platform stabilized gyroscopically within a system of gimbals. Image:PIGA_accelerometer_1.png A critical requirement for accuracy is low static friction (stiction) in the bearings of the pendulum; this is achieved by various means ranging from double ball bearing with a superimposed oscillatory motion to dither the bearing above its threshold or through the use of gaseous or fluid bearings or by the alternative method of floating the gyroscope in a fluid and restraining the residual mass by jewel bearings or electromagnetic means.
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