Zero insertion force

Zeroing, 13 464-465 Zero-insertion-force (ZIF) connector, in virtual two-way SMA devices, 22 347 Zero-linked hemoglobin, 4 122 Zeroth-order chemical kinetics... 

Finally, when a circuit or component doesn t have to be removed often and it contains a large number of transistors, typically you use a PGA and a ZIP (Figure 1.9). PGA stands for Pin Grid Array, describing the array of pins used to connect the chip to the circuit board. ZIF stands for zero insertion force, which describes how easy it is to place a chip in this kind of socket. It is a type of socket that works with PGA chips to allow them to be mounted on a circuit board. 

X number of structural units in a poly- ZIF zero insertion force... 

Connectors comprise approximately 75 to 80 percent of odd-form components. See Fig. 40.6. For example, there are universal serial bus (USB) connectors, dual inline memory module (DIMM) connectors, phone jacks, and zero-insertion-force (ZIF) connectors, as well as a variety of surface-mount connectors. Other odd-form components include sockets, electrolytic capacitors, transformers or large inductors, LEDs, relays, switches, as well as speakers and vibrators for handheld communications devices. In surface-mount technology, odd-form components are most often through-hole packages, including both passive and active devices as well as connectors. When addressing such odd-form components, the first step is to check the availability of an equivalent surface-mount version since there has been a shift toward surface-mount versions of many of these devices. Of course, the materials used to construct the surface-mount replacement must survive the reflow furnace environment, and especially the Pb-free reflow temperatures, particularly connectors because of their complex internal construction. In some cases, it has been possible to replace the through-hole connector with one of a variety of solderless products. 

The first finite element schemes for differential viscoelastic models that yielded numerically stable results for non-zero Weissenberg numbers appeared less than two decades ago. These schemes were later improved and shown that for some benchmark viscoelastic problems, such as flow through a two-dimensional section with an abrupt contraction (usually a width reduction of four to one), they can generate simulations that were qualitatively comparable with the experimental evidence. A notable example was the coupled scheme developed by Marchal and Crochet (1987) for the solution of Maxwell and Oldroyd constitutive equations. To achieve stability they used element subdivision for the stress approximations and applied inconsistent streamline upwinding to the stress terms in the discretized equations. In another attempt, Luo and Tanner (1989) developed a typical decoupled scheme that started with the solution of the constitutive equation for a fixed-flow field (e.g. obtained by initially assuming non-elastic fluid behaviour). The extra stress found at this step was subsequently inserted into the equation of motion as a pseudo-body force and the flow field was updated. These authors also used inconsistent streamline upwinding to maintain the stability of the scheme. 

The measured variables ji obtained from the faulty system model and the outputs yi of the non-faulty system model may be coupled by feeding the differences y,- - y,-into modulated sinks that deliver an output r, so that their input becomes zero. These sinks are termed residual sinks. The output r, of a residual sink is a power variable and is inserted into the balance of power variables at that junction in the non-faulty system model from which its co-variable y, is obtained. The outputs of the residual sinks are additional inputs into the non-faulty system model that force the faultless system to alter its behaviour so that it becomes identical to the one of the faulty system. If no fault is introduced into the real system model, then there are no differences and all values r, (f) are close to zero. Differences, however, lead to values r, (r) that remain distinguishably different from zero as long as a fault is effective, i.e. is not repaired. That is, the outputs of the residual sinks can serve as fault indicators. The balance of power variables at a junctions in the non-faulty system model connected to a residual sink becomes an ARR when unknowns have been eliminated and the output of the residual sink becomes the residual of that ARR. 

Short circuit Consider two electrodes inserted in each compartment. If these electrodes are short circuited, the potential difference (V l — >/ ii) is made zero, and an electrical current / is allowed to flow across the membrane. If the experiment is carried out at equal salt concentrations in I and n, so that (In Cl —In cn) = 0, and hence we have = 0 Aci = 0) th oiily remaining driving force is the... 

The first way is to insert special elements called zero compliances (ZC) [7]. These elements are physically equivalent to infinite stiffness dampers where the relative displacement is zero (and therefore so is the velocity). These elements introduce new variables into the system that are the forces of reaction in the kinematic constraints. The form of the equations to be obtained by using these elements will be seen in the following section. 

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