Traveling wave technique

Ametani, A. 1973. Modified traveling-wave techniques to solve electrical transients on lumped and distributed constant circuits Refraction-coefficient method. Proc. lEE 120(2) 497-504. 

Since this early work, interest has been focused mainly on oscillations and traveling waves during chemical reactions 49, 126-129). Butler et al. 130) employed MRI techniques to investigate the extent of reaction in a single crystal of... 

A useful technique which can be applied in cases where constant velocity solutions arise is that of changing from a fixed coordinate system (the present x coordinate has an origin whose position is fixed in space) to travelling-wave coordinates. With the latter, the origin moves from left to right with the front at the same constant velocity c we are constantly adjusting our frame of reference so that within the frame the reaction front appears stationary. This new coordinate z is defined in terms of x and t by... 

Using the experimental values for the width of the traveling wave front (portion be, Fig. 8), let us estimate the propagation velocity for the case of a thermal mechanism based on the Arrhenius law of heat evolution from the known relationship U = a/d, where a 10"2 cm2/s is the thermal conductivity determined by the conventional technique. We obtain 5 x 10"2 and 3 x 10-2cm/s for 77 and 4.2 K, respectively, which are below the experimental values by about 1.5-2 orders of magnitude. This result is further definite evidence for the nonthermal nature of the propagation mechanism of a low-temperature reaction initiated by brittle fracture of the irradiated reactant sample. 

Linear Mass Experiments. Using long strips of natural rubber (60 cm X 2 mm X 0.5 mm) coated with a 15% PAA solution in NMP, the mass per unit length of the sample was obtained as a function of temperature. The technique involves measuring the tension on the sample and the time of flight of a traveling wave on the sample (M. Chipalkatti,... 

Chirped pulse amplification is achieved using a pulsed traveling wave tube amplifier (TWTA, Amplifier Research 1000TP8G18) with peak power or 2 kW (7-18 GHz). The final pulse is shown as an inset in Figure 1. The spurious signals in the pulses we create using this technique are at least 20 dB lower in power than the instantaneous sweep frequency across the full 11 GHz range of the pulse. 

Individual cells can be identified on the basis of differences in size and dielectric properties using electrical techniques that are non-invasive and label-free. Characterization of the dielectric properties of biological cells is generally performed in two ways, with AC electrokinetics or impedance analysis. AC electrokinetic techniques are used to study of the behavior of particles (movement and/or rotation) and fluids subjected to an AC electric field. The electrical forces act on both the particles and the suspending fluid and have their origin in the charge and electric field distribution in the system. They are the basis of phenomena such as dielectrophoresis [10-14], travelling wave dielectrophoresis [15, 16], electrorotation [17, 18] and electroorientation [19]. 

In this chapter, we describe the technique of Fourier transform microwave spectroscopy. We distinguish here two rather different types of sample absorption cells which require somewhat different theoretical descriptions. First, we describe the theory for the relatively broad-band waveguide absorption cell in which the radiation is described as a traveling wave. Second, we describe the narrow-band Fabry-Perot cavity absorption cell in which the radiation is described as a standing wave. 

The major application of dielectrophoresis in micro- and nanofluidic systems continues to be the manipulation of particles and cells. Popular applications include particle trapping, dielectrophoretic microsystems, traveling wave dielectrophoresis, and determination of cell dielectric properties. The specific dielectrophoretic techniques used in existing applications are too numerous to cover in this entry. This entry does provide a brief overview of some of the established manipulation techniques. 

In Chapter 1, we introduced the Brusselator model as the first chemical model to demonstrate oscillations and traveling waves. We will now analyze the Brusselator to illustrate how one might use the techniques that we have discussed to establish the behavior of a two-dimensional system. We recall that the equations are ... 

AC Dielectrophoresis Lab-on-ChIp Devices, Rgure 2 DIelectrophoretIc manipulation techniques (a) electrorotation, (b) electro-orientation, (c) particle trapping and (d) traveling wave dielectrophoresis... 

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