Impedance embedded

The optical discharging condition is the same. The well width is 5.9 nm and the barrier width is kept at 2nm. The bias voltages are Vo=1.29,Via=-Vi=-0.30V, Vib=0 volts. The output power of the first harmonic is 24.2 mW for diode area of 100 pm. The embedding impedance for the first harmonic is 0.57+j0.86 2. Fig.2 shows simulation results. The residual gap is 0.162 eV, greater than in Example 1. Hence the dc bias voltage need be set at a higher value and the well width is assigned a smaller value. 

After introduction a prototype of intelligent multi-sensor system for driver status monitoring— DeCaDrive is presented in Section 2. The system expansion with embedded impedance spectroscopy sensor, its analog front-end and sensor data preprocessing are addressed in Section 3. Multi-sensor feature computation and data fusion as well as neural network based pattern classification are discussed in Section 4. The extended system is validated and evaluated by presenting the experimental results in Section 5. Finally, with future perspectives the current work is concluded in Section 6. 

Figure 1. DeCaDrive intelligent multi-sensor system for driver status monitoring with embedded impedance spectroscopy.

The dry electrodes being used to build embedded impedance spectroscopy sensor are having the following characteristics ... 

When working with phased arrays, it is of particular interest to compare the scan impedance with the embedded impedance, in particular whether one can be derived from the other. 

The embedded impedance, on the other hand, is the terminal impedance observed at just one element usually located somewhere in the middle of the array and with all the other elements terminated in loads (usually resistive). Thus, a terminal voltage is only applied to a single element, while all the other elements are excited parasitically. 

It is also of interest to consider the case where we excite a single column or row with identical voltages while all the other elements are terminated in loads like before. The impedance measured at the terminals of the column of elements in question is often called the embedded stick impedance Zgmb stk- We shall see that it often makes more sense to consider the embedded stick impedance rather than the embedded impedance of a single element. 

Although there are similarities between the scan and embedded impedances, they are distinctly different. Only the scan impedance can be associated with the direction of the beam, while the embedded impedance can be associated with only one direction. (Actually the pattern looks more like an element pattern with ripples.) However, not even for broadside scan do we obtain more than an occasional similarity between the two types of impedance. 

Needless to say, the embedded impedance for a single element is by far the simplest of the three types of impedance to implement. You only need a single connector at one element in the middle of the array, while all the others are terminated by resistors that can be either soldered in place or simply printed. In contrast, measurements of the scan impedance may require a connector or equivalent at each element, and, most importantly, we must be able to apply voltages at each terminal and be able to control these voltages in phase as well as amplitude. 

For these reasons there has long been a strong tendency to measme just the embedded impedance of a single element. While this may be a good way to check certain fundamental features of the array and in some cases the presence of surface waves, it cannot be emphasized enough that it is not a substitute for measuring the scan impedance, not even at broadside. And of these two impedances, the latter is by far the most important. In fact the embedded impedance has always reminded the author of an honorable degree. There is not much you can do with it except marvel at it ... 

But let us now look at the facts of the scan and the embedded impedances. D.2 THE SCAN IMPEDANCE... 

In the previous section we considered the impedance properties when an entire column array was fed at all its terminals. However, as was pointed out already in the Introduction, the embedded impedance will in general be obtained by exciting only one pair of terminals while all other terminals are just loaded. 

Thus, we therefore show the scan impedance for the center column in Fig. D.9 when the two outer colunms are excited as well. Similarly we show the scan impedance for the two outer columns in Fig. D.IO. Comparing the scan impedances in Figs. D.9 and D.IO with the embedded impedance Zemb stk in Fig. D.6 readily shows a significant improvement in particular at the lower frequencies. In the midrange we observe the presence of a surface wave. It has been suppressed by feeding each element with a voltage generator that includes a... 

It does not seem possible to obtain the scan impedance Za from any embedded impedance. Thus, let us discuss how to obtain Za by measurement. Two schemes come to mind. 

The investigation in this appendix clearly shows that the scan impedance and the embedded impedance are not the same, not even for broadside scan. 

The fundamental reason for this is actually well known but practiced very little. In fact the embedded impedance is often demanded of the sponsors primarily for no other reason than we have always done it that way in the past. ... 

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