Signal sinusoidal

The internal representation of any audio signal can now be calculated by using the transformations given in the previous section. The quality of an audio device can thus be measured with test signals (sinusoids, sweeps, noise etc) as well as real life signals (speech, music). Thus the method is universally applicable. In general audio devices are tested for transparency (i.e. the output must resemble the input as closely as possible) in which case the input and output are both mapped onto their internal representations and the quality of the audio device is determined by the difference between these input (the reference) and output internal representations. 

It was shown in the section on complex plane analysis that the double layer capacitance Qi is obtainable from the maximum value of Z" in the semicircular region, where l/coC = / ct- There are situations, however, where Q is the prime quantity of interest, and in these cases the faradaic current is either zero or very small (/ ct Small-signal sinusoidal excitation is then a good way of measuring Ccn, and the analysis is a good deal simpler than the full complex plane analysis which is required when/ ct is small. 

The electromechanical actuation tests were ideally performed using a potentiostat to control the applied voltage or current and the type of signal (sinusoidal, triangle and square wave). As for trilayer devices operating in electrolyte medium, the working electrode input of the potentiostat is connected to one electrode of the actuator while... 

The instrument uses a sinusoidal driver. The spectrum is very clean as we use a 14 bits signal generator. The probe signal is modulated in amplitude and phase by a defect signal. The demodulation is intended to extract the cartesian values X and Y of this modulation. 

Fig. 4. The effect of temperature for Mng 6 Zng 3 Fe Fe on (a) initial magnetic permeabiUty, )J., measured on a polycrystalline toroid appHed as a core for a coil driven by a low (B <0.1 mT) ampHtude, low (10 kHz) frequency sinusoidal signal and (b) magnetocrystalline anisotropy constant, measured on a monocrystalline sphere showing the anisotropy/compensation temperature Tq and the Curie temperature, T. To convert joules to calories, divide by...

Kinds oi Inputs Since a tracer material balance is represented by a linear differential equation, the response to anv one kind of input is derivable from some other known input, either analytically or numerically. Although in practice some arbitrary variation of input concentration with time may be employed, five mathematically simple input signals supply most needs. Impulse and step are defined in the Glossaiy (Table 23-3). Square pulse is changed at time a, kept constant for an interval, then reduced to the original value. Ramp is changed at a constant rate for a period of interest. A sinusoid is a signal that varies sinusoidally with time. Sinusoidal concentrations are not easy to achieve, but such variations of flow rate and temperature are treated in the vast literature of automatic control and may have potential in tracer studies. 

The apphcation of an impressed alternating current on a metal specimen can generate information on the state of the surface of the specimen. The corrosion behavior of the surface of an electrode is related to the way in which that surface responds to this electrochemical circmt. The AC impedance technique involves the application of a small sinusoidal voltage across this circuit. The frequency of that alternating signal is varied. The voltage and current response of the system are measured. 

In a second kind of infrared ellipsometer a dynamic retarder, consisting of a photoelastic modulator (PEM), replaces the static one. The PEM produces a sinusoidal phase shift of approximately 40 kHz and supplies the detector exit with signals of the ground frequency and the second harmonic. From these two frequencies and two settings of the polarizer and PEM the ellipsometric spectra are determined [4.316]. This ellipsometer system is mainly used for rapid and relative measurements. 

Fig. 5.12. Stress versus time responses (measured currents) for (a) fee 28.5-at. % Ni above 2.5 GPa (25 kbar), (b) below 2.5 GPa, and (c) for bcc 28.5-at. % Ni, reveal substantial differences in mechanical response. Such records at different input stresses are used to determine the various stress-volume relationships (after Graham et al. [67G01]). Time increases from right to left. Timing waves (upper sinusoidal signal) are 10 MHz.

More sophisticated instruments use special circuitry to obtain the rms values of non-sinusoidal signals. The current converter usually consists of low-value resistors in the input, and one of these is chosen as a shunt resistor... 

Much present electronic equipment deals with signals which are not sinusoidal and which may not even be periodic in nature. However, these signals can be divided into a series of components, each of a single specific frequency, and each can then be studied in turn in order to determine its characteristics. Where plant instrumentation is concerned, this technique can be particularly useful for diagnostic purposes. 

Theory. If two or more fluorophores with different emission lifetimes contribute to the same broad, unresolved emission spectrum, their separate emission spectra often can be resolved by the technique of phase-resolved fluorometry. In this method the excitation light is modulated sinusoidally, usually in the radio-frequency range, and the emission is analyzed with a phase sensitive detector. The emission appears as a sinusoidally modulated signal, shifted in phase from the excitation modulation and partially demodulated by an amount dependent on the lifetime of the fluorophore excited state (5, Chapter 4). The detector phase can be adjusted to be exactly out-of-phase with the emission from any one fluorophore, so that the contribution to the total spectrum from that fluorophore is suppressed. For a sample with two fluorophores, suppressing the emission from one fluorophore leaves a spectrum caused only by the other, which then can be directly recorded. With more than two flurophores the problem is more complicated but a number of techniques for deconvoluting the complex emission curve have been developed making use of several modulation frequencies and measurement phase angles (79). 

FT is essentially a mathematical treatment of harmonic signals that resolved the information gathered in the time domain into a representation of the measured material property in the frequency domain, as a spectrum of harmonic components. If the response of the material was strictly linear, then the torque signal would be a simple sinusoid and the torque spectrum reduced to a single peak at the applied frequency, for instance 1 Hz, in the case of the experiments displayed in the figure. A nonlinear response is thus characterized by a number of additional peaks at odd multiples of the... 

This system produces a steady laminar flow with a flat velocity profile at the burner exit for mean flow velocities up to 5m/s. Velocity fluctuations at the burner outlet are reduced to low levels as v /v< 0.01 on the central axis for free jet injection conditions. The burner is fed with a mixture of methane and air. Experiments-described in what follows are carried out at fixed equivalence ratios. Flow perturbations are produced by the loudspeaker driven by an amplifier, which is fed by a sinusoidal signal s)mthesizer. Velocity perturbations measured by laser doppler velocimetry (LDV) on the burner symmetry axis above the nozzle exit plane are also purely sinusoidal and their spectral... 

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