the electrical engineering handbook second edition

... coefficients in the same manner as the coefficient of utilization. The room position multiplier is a function of the room cavity ratio and of the location in the room of the point where the illumination ... b.Reduce the area of high luminance causing the glare condition. c.Increase the angle between the glare source and the line of vision. d.Increase the luminance of the area surrounding the glare ... b.Determine the coefficient of utilization ( CU ) which is the ratio of the lumens reaching the working plane to the total lumens generated by the lamps. This is a factor that takes into account the efficiency

Ngày tải lên: 30/12/2013, 22:33

... tensile stress in the x-direction, for example, will strain the lattice in the xy-plane and destroy the three-fold symmetry, thereby lifting the degeneracy of the energy minima. However, the four-fold ... LLC According to the deformation potential theory, the strain will shift the energy of all the states in a given band extremum by the same amount, i.e., the valley moves along the energy scale ... perpendicular to the valley. For an applied E field parallel to the stress, the conductivity will increase (i.e., the resistivity decreases) relative to the unstressed state because of the increase in the

Ngày tải lên: 30/12/2013, 22:33

... superconductor. The correlations of the electrons in the superconductor must lower the overall energy of the system or else the material would not be superconducting in the first place. Because the critical ... the two-fluid model, the electrical current density, J , is carried by both the uncorrelated (normal) electrons and the superelectrons: J = J n + J s where J n is the normal current density. The ... (53.18) In other words, once the supercurrent channel carries its maximum amount of current, the rest of the current is carried through the normal channel. Just as the correlated motion of the superelectrons

Ngày tải lên: 30/12/2013, 22:33

... assumed not to disturb the trapped charge; the received electrical signal is then correlated with the acoustical wave to determine the profile of the trapped charge. Errors in the measurement would ... assumes the form [Watson, 1995] (55.14) where n(E) is the trap density and n is the attempt jump frequency of the electrons. The electron current displays the usual t –1 dependence and the plot ... current due to the deep traps. The mobility of the free charge carriers is determined by the depth of the traps, the field resulting from the trapped charges, and the temperature. As elevated temperatures

Ngày tải lên: 30/12/2013, 22:33

... employed. The mercury thermometer was mentioned in the Introduction as a nonelectrical sensor. The most commonly used electrical temperature sensors are thermocouples, thermistors, and resistance thermometers. ... As the electrons in the metal gain thermal energy, they move about more rapidly and undergo more frequent collisions with each other and the atomic nuclei. These scattering events reduce the ... of the wire to a cantilever beam, with one end of the wire at the attached beam end and the other at the free end. The cantilever beam free end moves in response to an applied force, such as the

Ngày tải lên: 30/12/2013, 22:33

... data, the same thermal process can be applied while reversing the direction of the bias magnetic field. To read the stored information optically, the Kerr effect is used to detect the presence of these ... by the laser passes through the second polarizer being oriented at 45 degrees relative to the transmission axis of the first polarizer. Any subsequently reflected light is then returned through the ... another 45 degrees through the Faraday material, and, because its polarization is now 90 degrees from the incident beam, is deflected by the first calcite prism. The four ports of the circulator then

Ngày tải lên: 30/12/2013, 22:33

... that the operator can correct the position of the wand until the cursor is properly placed. At this time the information from the tablet may also be transferred to either the host computer or the ... Y electrical pulses into the matrix. By determining the number of pulses in a time period, the location of the wand is established. Another similar device used magnetostrictive rather than electrical ... a pulse of light at the point on the screen of the CRT or surface of any other light-emitting device where the point of the pen is placed. This is accomplished by means of the circuit shown in

Ngày tải lên: 30/12/2013, 22:33

... mass of the international prototype of the kilogram (3rd CGPM, 1901). Second ? ?The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two ... present. 2 The values of these units in terms of the corresponding SI units are not exact, since they depend on the values of the physical constants e (for the electronvolt) and N a (for the unified ... Tallarida, R.J. “Section XII – Mathematics, Symbols, and Physical Constants” The Electrical Engineering Handbook Ed. Richard C. Dorf Boca Raton: CRC Press LLC, 2000 The mathematical equation used to

Ngày tải lên: 31/12/2013, 21:25

... of all the branch currents and voltages as the state of the network, then the knowledge of the instantaneous values of all these variables determines this instantaneous state. Not all of these ... variables as the state variables in order to formulate the state equations. If we call the set of instantaneous values of all the branch currents and voltages the state of the network, then the knowledge ... variables. State: A set of data, the values of which at any time t, together with the input to the system at the time, determine uniquely the value of any network variable at the time t. State equation

Ngày tải lên: 31/12/2013, 21:25

... figure, the second band is the second significant figure, the third band is the multiplier or the number of zeros that have to be added after the first two significant figures, and the fourth band is the ... range of the resistor is the highest frequency at which the impedance differs from the resistance by more than the tolerance of the resistor. The frequency effect on resistance varies with the resistor ... rectangular in shape; therefore the length l divided by the width w gives the number of squares within the resistor (Fig. 1.2). The number of squares multiplied by the resistivity is the resistance.

Ngày tải lên: 31/12/2013, 21:26

... d ( t ) is shown in Fig. 2.2. The notation K in the figure refers to the area of the impulse K d ( t ). The unit-step function u ( t ) is equal to the integral of the unit impulse d ( t ); more ... q). Here A is the amplitude, w is the frequency in radians per second (rad/s), and q is the phase in radians. The frequency f in cycles per second, or hertz (Hz), is f = w/2p. The sinusoid is ... value of time that makes the exponent –1. When t = t = the time constant, the value of the exponential factor is In other words, after a time equal to the time constant, the exponential factor

Ngày tải lên: 31/12/2013, 21:26

... voltage is the difference between the potential of the node entered and the potential of the node at which the path exits. Alternatively, the voltage drop along a branch is the difference of the node ... orientation in the sense that in “walking” along the path one would enter one of the nodes and exit the other. This establishes a direction for determining the voltage across a branch in the path: the voltage ... the associated current is said to be entering the node; if the arrow is drawn away from the node, the current is said to be leaving the node. The current i 1 is entering node b in Fig. 3.1; the

Ngày tải lên: 31/12/2013, 21:26

... © 2000 by CRC Press LLC The roots of the numerator polynomial N ( s ) are the zeros of the system, and the roots of the denominator D ( s ) are the poles of the system (the points of infinite response). ... gives the Thomson denomi- nator polynomials. The numerator is a constant equal to the dc gain of the circuit multiplied by the denominator constant. The cut-off frequencies are not all 1 rad/s. They ... which the magnitude is 0.707 (–3 dB) of the dc level and is the dividing line between the passband and the stopband . In the above example we see that the magnitude of V o / V i at w = 0 (dc)

Ngày tải lên: 31/12/2013, 21:26

... because the biased diode is in parallel with the output. Although the circuits behave the same way whether or not one side of the dc voltage source is connected to the common (low) side of the input ... constant, and T is the temperature of the semiconductor. Around the knee of the curve in Fig. 5.2 is a positive voltage that is termed the turn-on or sometimes the threshold voltage for the diode. This ... 5.5. The resonant frequency of the LC filter should be lower than the fundamental frequency of the rectifier output for effective performance. The ac portion of the output signal is reduced while the

Ngày tải lên: 31/12/2013, 21:26

... Property The convolution integral signal y(t) can be expressed as where x(t) denotes the input signal, the h(t) characteristic signal identifying the operation process. The Laplace transform of the ... Function The autocorrelation function of the signal x(t) is formally defined by The Laplace transform of the autocorrelation function is and the corresponding region of absolute convergence is Other ... follow that the real part of the exponential argument be positive, that is, Re( s + a ) = Re( s ) + Re( a ) > 0 If this were not the case, the evaluation of expression (6.1) at the upper limit

Ngày tải lên: 31/12/2013, 21:26

... s(t). The peak magnitude of the Gibbs oscillation is 13% of the size of the jump discontinuity s(t 0 – ) –s(t 0 + ) regardless of the number of terms used in the approximation. As N increases, the ... is discontinuous the Fourier series converges to the average of the limiting values to the left and right of the discontinuity. For example, if t 0 is a point of discontinuity, then s¢(t 0 ) = ... terms, and b 0 is the dc level of the signal. Therefore, if it can be determined by inspection that a signal has a dc level, or if it is even or odd, then the correct form of the trigonometric

Ngày tải lên: 31/12/2013, 21:26

... frequency response plot with the real part of the transfer function on the abscissa and the imaginary part of the transfer function on the ordinate. Resonance: The enhancement of the response of a physical ... curves for the transfer function, the curves for the individual terms are added together. The terms used as the basis for drawing Bode diagrams are found from factoring N(s) and D(s), the numerator ... lines. Example 2 Note that the damping factor for the quadratic term in the denominator is z = 0.35. If drawing the response curves by hand, the resonance peak near the breakpoint at w = 100 would

Ngày tải lên: 31/12/2013, 21:26

... furthermore allowed the engineer to see the effects of small changes in the gain, K, on the stability of the system. The root-locus diagram shows the location in the s-plane of the poles of the ... then the Lyapunov method is the most popular choice for stability analysis. If the system is linear, then the direct application of Theorem 12.5 is more attractive, since the eigenvalues of the ... and turned up the thermostat on the heater. The house warmed up. She got hot, so she got up and turned down the thermostat. The house cooled off. She got cold and turned up the thermostat. This

Ngày tải lên: 31/12/2013, 21:26

... give the total noise at the reference node. The equivalent input noise is then easily calculated from the transfer function between the circuit input and the reference node A is ( f ). The equation ... and D f is the bandwidth of the circuit. These noise sources are inserted as independent current sources, In j ( f ) into the AC model. The resulting current due to the noise source is then calculated ... in Fig. 13.1 that the numbers next to the wires represent the circuit nodes. These numbers are used to describe the circuit to the simulator. In most SPICE-type simulators the nodes are represented

Ngày tải lên: 31/12/2013, 21:26

... range over the CPI. The best accuracy performance occurs for the case of thermal noise-limited error. The resulting accuracy is the resolution of the radar divided by the square root of the S / ... Fast convolution consists of taking the FFT of the digitized receiver output, multiplying it by the stored FFT of the desired filter function, and then taking the inverse FFT TABLE 41.2 Pulse Radar ... is due to the antenna illumination factor. The common form of the radar range equation uses power gain rather than directivity. Antenna gain is equal to the directivity divided by the antenna

Ngày tải lên: 31/12/2013, 21:26