Dynamic resistance

Intrinsic resistance to dislocation motion can be measured in either of two ways direct measurements of individual dislocation velocities (Vreeland and Jassby, 1973) or by measurements of internal friction (Granato, 1968). In both cases, for pure simple metals there is little or no static barrier to motion. As a result of viscosity there is dynamic resistance, but the viscous drag coefficient is very small (10" to 10" Poise). This is only 0.1 to 1 percent of the viscosity of water (at STP) and about 1 percent of the viscosity of liquid metals at their... 

Resistance-Deflection Function. The resistance-deflection function establishes the dynamic resistance of the trial cross-section. Figure 4a shows a typical design resistance-deflection function with elastic stiffness, Kg (psi/in), elastic deflection limit, Xg (in) and ultimate resistance, r.. (psi). The stiffness is determined from a static elastic analysis using the average moment of inertia of a cracked and uncracked cross-section. (For design... 

For a current source ( Rac>>dV/dI ) we set I-Ig=Iucos(a)t). By matching Fourier components we find that the first harmonic signal Vu is proportional to the dynamic resistance of the junction ... 

The tunneling spectrum of a doped junction can be seen in Fig. 4. In this case we have an Al-A10x-4-pyridine-carboxylic acid-Ag sample, with approximately monolayer coverage, run at 1.4 K. Fig. 4a shows the modulation ( first harmonic ) voltage Vw across the junction as a function of applied bias. Since the modulation current Iu is kept constant, Vu is proportional to the dynamic resistance of the sample. The second harmonic voltage V2U ( Fig. 4b ), proportional to d V/dl, shows the vibrational spectrum of the absorbed molecules. As we shall see below, a quantity which is more closely related to the density of vibrational oscillator strengths D(r) is d I/dV. We show in Fig.4c the quantity... 

Figure 4. Tunneling characteristics of an Al-AlOx-4-pyridine-COOH-Ag junction run at 1.4 K with a 1 mV modulation voltage, (a) Modulation voltage Vu across the junction for a constant modulation current Iu. This signal is proportional to the dynamic resistance of the sample, (b) Second harmonic signal, proportional to d2V/dI2. (c) Numerically obtained normalized second derivative signal G , dG/ dfeVJ, which is more closely related to the molecular vibrational density of states, (d) Normalized G0 dG/d(eVJ with the smooth elastic background subtracted out...

In many applications, photodiodes operate at zero polarization. They must therefore have high dynamic resistance to ensure a high detectivity. This is achieved in US-A-4972244 by separating detector elements by trenches. Furthermore, a common electrode is provided at the bottom of the trenches thereby reducing the interconnection resistance of the photodiodes. 

Friction, dynamic — Resistance to continued motion between two surfaces, also known as sliding friction. 

The dynamic resistance I of a rectifier of cross-sectional area A, total forward current density 1 (amperes m-2), and total forward current It = IA (amperes) (i.e., the resistance to small increase in voltage dV added to the forward bias) is... 

Verification of the Capacitj and Dynamic Resistance Terms in the Equation Governing the Reversible Depolarising Process in an Alternating Field. Trans Farad. Soc. 42, 650 (1946). 

For non-ohmic resistors, R is a function of current and the definition R = dV/dl is far more useful. This is sometimes called the dynamic resistance. Solid state devices such as thermistors are non-ohmic, and non-linear. A thermistor s resistance decreases as it warms up, so its dynamic resistance is negative. Tunnel diodes and some electrochemical processes have a complicated /-Vcurve with a negative resistance region of operation. 

Since wet purification methods are insufficiently effective, solid sorbents are used. The systems based on calcium and aluminium oxides and hydroxides are promising as such sorbents. A sorbent should provide a minimum gas dynamic resistance, therefore, it is produced as the granules of complicated shape. Sorbents based on lime and aluminium hydroxide are good fluorine absorbers. However, lime sorbents do not possess sufficient mechanical strength, while the use of aluminium hydroxide alone as a sorbent is limited by its high cost. 

The dynamic resistance is essentially the resistance change with temperature but includes also the phase changes from solid to liquid to vapor. We can express this resistance as dependent upon energy because, of course, the internal energy of the bridge is dependent upon temperature. 

The quantity expressed as the integral of energy deposited in the bridge divided by dynamic resistivity is essentially single valued (Ref 20), and can be considered, within practical limits, to be a constant that depends only upon the bridgewire material. The density is also only a function of bridgewire material. 

Dicofol resistance in spider mites, though of lesser practical importance in some agricultural systems than resistance to the organotin and organosulfur acaricides, provides a system conducive to the study of resistance dynamics. Resistance is generally manifest as a >1000-fold difference in susceptibility of resistant versus susceptible individuals to dicofol residues (12 .). ... 

Of particular interest are the block honeycomb-structure SHS catalysts. In these catalytic systems, the gas-dynamic resistance is much lower than in conventional ones, the catalytic layer is immobilized, and the active surface is used more efficiently. The data on the oxidation of carbon monoxide and propane in the block oxynitride SHS catalyst (1.5% CO, 1.5% CsHg, 10% O2 W=7010 h ) are presented in Fig. 4. Note, that at high flow rates, the conversion degree for carbon monoxide and propane attains 100% at 450-500 C. The temperature of complete oxidation can be lowered upon immobilization of the "id transition metals (Co, Ni, Cr, and Fe) oxides on the catalyst surface. Efficiency of the catalysts with immobilized Co and Ni oxides (0.2%) for the oxidation of carbon monoxide and propane is shown in Fig. 5. In this case, carbon monoxide is oxidized at 400-450"C while propane is oxidized at 125-175°C. 

Several animal inhalation toxicity studies have been conducted on various jet fuels (summarized in Table 4-2). In one study, male F344 rats were exposed to shale-oil-derived JP-4 continuously for 90 days by inhalation at 1,000 mg/m3. The exposure resulted in no effects on lung volumes, dynamic resistance and compliance, quasistatic compliance, partial and full forced vital capacities, carbon monoxide diffusion capacity, and closing volume. There... 

As shown in the previous section, the mechanical properties of a quartz crystal close to resonance frequency can be expressed by means of a motional impedance. To complete the equivalent circuit of a quartz crystal, the capacitance, Co, must be added in parallel to the motional impedance. It results in the Butterworth-Van Dyke (BVD) equivalent circuit of a quartz crystal, as shown again in Fig. 8 for an unloaded quartz crystal [32]. In this notation common in electronic Hterature, Is is the dynamic inductance and is imder-stood here as a representation of the oscillating mass of the quartz crystal. Cs is the dynamic capacitance and reflects the elasticity of the oscillating body. Rs is the dynamic resistance and returns friction of the quartz slice as well as all kinds of acoustic damping. 

A nonspherical particle is generally anisotropic with respect to its hydro-dynamic resistance that is, its resistance depends upon its orientation relative to its direction of motion through the fluid. A complete investigation of particle resistance would therefore seem to require experimental data or theoretical analysis for each of the infinitely many relative orientations possible. It turns out, however, at least at small Reynolds numbers, that particle resistance has a tensorial character and, hence, that the resistance of a solid particle of any shape can be represented for all orientations by a few tensors. And the components of these tensors can be determined from either theoretical or experimental knowledge of the resistance of the particle for a finite number of relative orientations. The tensors themselves are intrinsic geometric properties of the particle alone, depending only on its size and shape. These observations and various generalizations thereof furnish most, but not all, of the subject matter of this section. 

These intrinsic stress fields play fundamental roles in the theory of the hydro-dynamic resistance of particles in the Stokes regime. 

ISO 11343, 1993, Adhesives—Determination of dynamic resistance to cleavage of high strength adhesive bonds under impact conditions- Wedge impact method The method is mainly aimed for the characterisation of metal substrates suitable for automotive applications. An instrumented impact testing machine (pendulum type) of 50-300 J and. 3-5.5ms maximum capacity is required for this test. A blunt wedge of approximately 1 mm tip radius and included angle of 8 is impact driven into a bonded joint at 3 ms" for aluminum alloy adherends and 2 ms" for steel adherends. The impact event should be... 

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