Joining for lightweight vehicles

P.1000. Mallick , in Materials, Design and Manufacturing for Lightweight Vehicles (Second Edition), 2021

8.seven.3 Resistance element welding

In resistance chemical element welding (REW), a headless steel rivet (element) is punched into the upper canvass of the sheet stack by a strength applied past the peak electrode of the spot welding machine and the rivet lesser is then resistance spot welded to the bottom sheet ( Oh et al., 2019). In aluminum–steel assembly, the upper sail is aluminum and the lower sheet is steel. The REW procedure is very similar to the RSR process; its main advantages over RSR are that it does not require a predrilled hole and the rivet head does not protrude out. As with RSR, the equipment for REW is the same equally that used for RSW.

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Accompaniment Systems

Claire Soares , in Gas Turbines, 2008

Temperature Monitoring

A number of platinum wire resistance elements installed in unlike parts of the auto are used for continuous monitoring of the temperature of the parts. The connection cables of the elements are routed to junction boxes on the exterior of the stator housing. The number and location of the elements are shown in the post-obit list:

Number Location
6 In stator winding, betwixt coil sides (2/phase)
two Cooling air supply
two Cooling air exhaust
i Cooling air frazzle from exciter

As a standard, the resistance elements accept a resistance of 100 ohms at 0°C.

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Process Control

William A. Poe , Saeid Mokhatab , in Modeling, Control, and Optimization of Natural Gas Processing Plants, 2017

3.one.i Resistance-Type Processes

The characteristic of a resistance element is the ability to transfer material or energy. Flow through a pipe is the nearly common example of a resistance-blazon process. A strictly resistance-type procedure has a proportional only response. Any change in the resistance, for example, a control valve opening, will issue in an immediate proportional change in the flow. The amount of alter is a part of the procedure gain. Whatever change in the load, for case, the upstream and downstream pressure in this case of flow through a pipage, volition also result in an immediate proportional modify in the menstruation. The corporeality of change is once more a part of the process gain.

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Procedure Command Fundamentals

Saeid Mokhatab , William A. Poe , in Handbook of Natural Gas Manual and Processing, 2012

14.two.1 Resistance-Type Processes

A characteristic of a resistance element is the ability to transfer material or free energy. Flow through a pipe is the almost common case of a resistance-type process. A strictly resistance-blazon process has a proportional-only response. Whatsoever change in the resistance—for instance, a control valve opening—will consequence in an firsthand proportional change in the menses. The amount of alter is a part of the process proceeds. Whatever change in the load—for case, the upstream and downstream pressure in this example of menstruation through a pipe—volition also result in an immediate proportional alter in the flow. The amount of change is again a function of the process gain.

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Acoustic components

Leo L. Beranek , Tim J. Mellow , in Acoustics: Sound Fields and Transducers, 2012

Definition of Q

If this mass-resistance element is used with a compliance to class a resonant circuit, we are ofttimes interested in the ratio of the angular frequency of resonance ω 0 to the angular bandwidth ω (rad/s) measured at the half-power points. This ratio is called the "Q" of the circuit and is a measure of the sharpness of the resonance curve.

The "QA " of a perforated sheet when used with a compliance of such size every bit to produce resonance at angular frequency ω 0 is

(iv.27) Q A = ω 0 M A R A = ω 0 ρ 0 2 μ a t + ane.7 a ( 1 − ( a / b ) ) t + 2 a ( 1 − ( π a ii / b 2 ) )

The QA is independent of the number of holes in the perforated sheet. Nosotros echo that these formulas are limited to cases where the centers of the holes are spaced more than a diameter apart.

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Control systems

West. Bolton , in Control Systems, 2002

1.4.1 Potentiometer

A potentiometer consists of a resistance element with a sliding contact which can be moved over the length of the element and connected as shown in Figure ane.13. With a abiding supply voltage Five s, the output voltage V o between terminals 1 and 2 is a fraction of the input voltage, the fraction depending on the ratio of the resistance R 12 between terminals 1 and two compared with the total resistance R of the entire length of the rails across which the supply voltage is continued. Thus V o /5 south = R 12 /R. If the track has a constant resistance per unit length, the output is proportional to the displacement of the slider from position one. A rotary potentiometer consists of a coil of wire wrapped circular into a round track or a circular film of conductive plastic over which a rotatable sliding contact tin can be rotated, hence an angular displacement can be converted into a potential divergence. Linear tracks can be used for linear displacements.

Figure 1.13. Potentiometer as a sensor of position

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Accessory Systems

Claire Soares , in Gas Turbines (2nd Edition), 2015

Command and Protection

Temperature Monitoring

A number of platinum wire resistance elements installed in unlike parts of the machine are used for continuous monitoring of the temperature of the parts. The connection cables of the elements are routed to junction boxes on the outside of the stator housing. The number and location of the elements are shown in the following list:

As a standard, the resistance elements accept a resistance of 100 ohms at 0°C.

Number Location
vi In stator winding, between coil sides (2/phase)
2 Cooling air supply
ii Cooling air exhaust
1 Cooling air frazzle from exciter

Bearing Vibration Measurement

Vibration transducers of seismic type for bearing vibration measurement tin can be delivered mounted on the begetting shields of the generator.

Heating Elements

Heating elements are installed in both the generator and exciter unit to prevent condensation during standstill of the generator at lower temperatures.

Electric current Transformers

Current transformers tin can be mounted on the stator terminals outside the generator casing. The transformers can exist delivered in accordance with the purchaser'south requirements.

Protective Equipment

The original equipment manufacturer recommends that the generator, every bit a minimum, be equipped with the following protective equipment:

•

Overcurrent protection

•

Overvoltage protection

•

Differential protection

•

Negative phase-sequence current protection

•

Stator earth fault protection

•

Rotor earth fault protection

•

Underexcitation protection and/or underexcitation limiter

•

Reverse power protection (depending on the drive machine type)

•

Overexcitation and/or overexcitation limiter

•

Loss-of-excitation protection; in installations where at that place is a risk of high overvoltages, a surge diverter is to be installed and, in certain cases, protective capacitors

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Instrumentation system elements

Westward. Bolton , in Instrumentation and Control Systems, 2004

ii.2.1 Potentiometer

A potentiometer consists of a resistance element with a sliding contact which tin be moved over the length of the element and continued as shown in Figure 2.1. With a constant supply voltage 5 due south, the output voltage V o between terminals 1 and 2 is a fraction of the input voltage, the fraction depending on the ratio of the resistance R 12 between terminals 1 and 2 compared with the full resistance R of the unabridged length of the track across which the supply voltage is connected. Thus 5 o/Five southward = R 12/R. If the track has a abiding resistance per unit of measurement length, the output is proportional to the displacement of the slider from position 1. A rotary potentiometer consists of a scroll of wire wrapped round into a circular track, or a round picture show of conductive plastic or a ceramic-metal mix termed a cermet, over which a rotatable sliding contact tin can be rotated. Hence an angular displacement can be converted into a potential difference. Linear tracks tin be used for linear displacements.

Figure ii.i. Potentiometer

With a wire wound track the output voltage does not continuously vary as the slider is moved over the track merely goes in small jumps as the slider moves from 1 plough of wire to the next. This problem does not occur with a conductive plastic or the cermet track. Thus, the smallest change in displacement which volition give rise to a change in output, i.due east. the resolution, tends to be much smaller for plastic tracks than wire-wound tracks. Errors due to non-linearity of the track for wire tracks tend to range from less than 0.1% to about ane% of the full range output and for conductive plastics tin can exist as low equally about 0.05%. The track resistance for wire-wound potentiometers tends to range from nigh 20 Ω to 200 kΩ and for conductive plastic from nigh 500 Ω to 80 kΩ. Conductive plastic has a college temperature coefficient of resistance than wire and so temperature changes accept a greater effect on accuracy.

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Instrumentation System Elements

William Bolton , in Instrumentation and Control Systems (Third Edition), 2021

2.9.2 Temperature Bounty

The electrical resistance strain gauge is a resistance element which changes resistance when subject to strain. However, information technology will also change resistance when subject to a temperature alter. Thus, in order to use it to make up one's mind strain, bounty has to exist made for temperature effects. Ane manner of eliminating the temperature effect is to utilize a dummy strain guess. This is a strain gauge identical to the i under strain, the active gauge, which is mounted on the aforementioned fabric as the agile approximate just not subject field to the strain. Information technology is positioned shut to the agile approximate and then that it suffers the same temperature changes. As a outcome, a temperature change volition cause both gauges to change resistance by the same corporeality. The agile gauge is mounted in ane arm of a Wheatstone bridge (Figure 2.57A) and the dummy gauge in an opposite arm and so that the effects of temperature-induced resistance changes cancel out.

Figure 2.57. Temperature compensation: (A) dummy gauge, (B) with four agile strain gauges.

Strain gauges are oftentimes used with other sensors such every bit diaphragm pressure gauges or load cells. Temperature compensation is however required. While dummy gauges could be used, a better solution is to use four strain gauges with two of them attached so that the applied forces put them in tension and the other ii in compression. The gauges that are in tension, gauges 1 and 3, will increment in resistance while those in compression, gauges 2 and iv, will decrease in resistance. The gauges are connected as the iv arms of a Wheatstone span (Figure 2.57B). Every bit all the gauges and and so all the arms of the bridge will be every bit affected by any temperature changes the arrangement is temperature compensated. The arrangement likewise gives a much greater output voltage than would occur with just a single active guess.

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Thermal modeling, analysis, and design

Hengyun Zhang , ... Wensheng Zhao , in Modeling, Analysis, Design, and Tests for Electronics Packaging beyond Moore, 2020

3.6.iii Anatomy of thermal resistance elements

It is of practical interest to examine the respective thermal resistance elements on the correct-hand side of Eq. (3.half-dozen.1). Such analysis has been conducted for both chip sizes and the results are illustrated in Figure 3.6.3. For both flake cases, the increase in flow rate from 0.1L/min to 1L/min leads to a reduction of 55% in R bi due to the enhanced convection. Coupled with a reduction in R sp of 13% for the 12   mm chip and 21% for the 10   mm chip, the overall decreases in R ji is 22% and 19%, respectively.

Instead of continuing to increase the flow rate, further thermal enhancement tin can be achieved through other means such as thinning of the wafer thickness and, peculiarly, the improvement of TIM performance. Considering an improved TIM with an impedance of 0.1   K   cmtwo/W, the thermal resistance based on the above assay is recalculated here for analogy. The calculated thermal resistances for the 12 and 10   mm scrap cases have been shown in Figure 3.six.five. It is seen that the thermal resistances for both chips are reduced by effectually thirty% on average due to the introduction of the advanced interface material. At a flow rate of 0.5L/min, the thermal resistance for the 12   mm fleck is 0.222   °C/W and, given a temperature window of lx   °C, the estimated power dissipation goes upwards to 270W without farther increase in organisation complexity and operation cost. The above example indicates that the TIM plays an of import role in reducing the junction to coolant inlet thermal resistance.

Effigy three.6.5. The breakdown of the thermal resistances for (a)12   mm chip and (b)10   mm chip.

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