Impedance-match method

An important application of the impedance match method is demonstrated by the pressure-particle velocity curves of Fig. 4.9 for various explosives. Using the above method, the pressure in shock waves in various explosives is inferred from the intersection of the explosive Hugoniot with the explosive product release isentropes and reflected shock-compression Hugoniots (Zel dovich and Kompaneets, 1960). The amplitudes of explosively induced shock waves which can be propagated into nonreacting materials are calculable using results such as those of Fig. 4.9. 

Calculate the final shock state pressure and density from the measured shock velocity of 5.77 km/s in a sample of glass (initial density 2.204 g/cm ) which is mounted onto a driver plate of pure Cu. The Cu driver plate is impacted at 4.5 km/s by a Ta flyer plate. Use the impedance match methods. 

In order to examine reactions involved in the shock process, we must first identify when the reaction occurs—a moment at which tlie shock front meets tlie hexane, otherwise a period that tlie shock wave is traveling through tlie hexane. It is physically deduced tliat tlie projectile lengtli controls tlie shock period if the physical property and projectile velocity remain constant According to the impedance-match method [161], shock periods for projectile lengths of 10, 20, and 40 mm were estimated at about 3.5, 7.0, and 14 ps, respectively. Total yield rates (total molar yield/shock period) of the products for each projectile velocity are plotted on a common curve independent of projectile lengtlis (Fig. 4.5), al-... 

Figure 9.10. Shock pressure versus particle velocity for water ice, and snow with different densities. Curves for serpentine with the impact velocity of Earth s escape velocity and ice with Ganymede s escape velocity are plotted for the estimation of shock pressure by means of impedance matching method. Escape velocities for satellites are indicated on the particle velocity axis. (Figure from /Vhrens and O Keefe [31].)...

Besides the application of micromirror arrays, nickel surface micromachining with a copper sacrificial layer is a technology that can be used for various microfabrication concepts. Only recently, the method has been applied for the construction of capacitive RF switches for antenna impedance matching in multiband mobile phones [26]. 

Two different methods for introducing a shock wave (which may or may not subsequently turn into a detonation wave) into the target AB material have been used. The first employs a thin, inert A2 solid flyer plate, which is launched at a velocity +2up towards the target, resulting in an initial particle velocity of +Up into the sample (and one of -t/p into the flyer plate, due to the virtually perfect impedance match of A2 and AB). If chemical reactions have not begun by the time the rarefaction (release-wave) fan from the rear end of the flyer plate overtakes the initial unreactive shock (a time proportional to the flyer plate thickness), then the shock wave decays and eventually fails to propagate. 

If the impedance of the inert material equals the impedance of the tested explosive, the velocity of the explosive charge/inert material interface will be related to the detonation products adiabatic shock. Consequently, the mass velocity of the detonation products at the CJ point might be determined directly, as given for instance in Figure 4.71. However, most frequently, the explosive/inert material interface velocity could be assigned neither to the velocity corresponding to the chemical spike state nor to the CJ point state, i.e., to the mass velocity of the detonation products. In such cases, the calculation of the detonation parameters at the CJ point is much more complex and requires knowing the adiabatic shock for the unreacted explosive, detonation products, and inert material, i.e., application of the extended impedance match solution method. 

The inner filling solution for the sensors is usually 0.01 M NaCl, which is also used to condition the potentiometric sensors. Electrochemical potential is measured with the following galvanic cell Ag/AgCl/bridge electrolyte/sam-ple solution/ion-selective membrane/inner filling solution/ AgQ/Ag. A high impedance pH-mV meter is used to measure the electrochemical potential. Selectivity coefficients are evaluated by the matched potential method (also known as method of mixed solutions), or via the separate solution method. 

The design of a potentiostat for impedance measurements is more critical than for other electrochemical methods [20-23]. In the case of impedance measurements the potentiostat must perform in such a way that the results obtained in the frequency range of interest are not influenced by the frequency and phase characteristics of the potentiostat and its control loop. The upper frequency limit of a given potentiostat is a frequency where the input AC voltage e(co) to the potentiostat matches the AC voltage on the cell. The frequency characteristic of the... 

The input impedance of an antenna plays an important role in the matching of the source to the antenna. Knowledge of the impedance over the operating bandwidth is of concern. The real part of the impedance is primarily due to the radiation resistance, and in part due to the ohmic loss of the conductors. The radiation resistance is the equivalent resistance, which if connected to the source in place of the antenna absorbs the same power as radiated by the antenna. Impedance can be determined a number of ways. Use of the method of moments gives the most definitive results subject to modeling limitations. Method of moments software was discussed in the first part of Sec. 13.1.3. 

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