Time domain performance specifications

Prom our point of view, each approach has its advantages. The first two model-based approaches have a more intuitive time domain performance specification than traditional frequency domain design methods. However, the frequency domain methods require less structural information about the process dynamics. Chapters 6 and 7 present a new frequency domain PID design approach that we feel combines these advantages. This new... 

Our goal for PID controller design is to achieve the desired closed-loop, time domain performance with respect to both the process output variable and the control signal responses. The key is to be able to link the frequency domain controller design with the time domain performance specification. To make this link, we examine the relationship between the desired... 

There are a number of criteria by which the desired performance of a closedloop system can be spedlied in the time domain. For example, we could specify that the closedloop system be critically damped so that there is no overshoot or oscillation. We must then select the type of controller and set its tuning constants so that it will give, when coupled with the process, the desired closedloop response. Naturally the control specification must be physically attainable. We cannot make a Boeing 747 jumbo jet airplane behave like an F-IS fighter. We cannot... 

The steadystate error is another time-domain specification. It is not a dynamic specification, but it is an important performance criterion. In many loops (but not all) a steadystate error of zero is desired, i.e, the value of the controlled variable should eventually level out at the setpoint. 

The dynamic performance of a system can be deduced by merely observing the location of the roots of the system characteristic equation in the s plane. The time-domain specifications of time constants and damping coefficients for a closedloop system can be used directly in the Laplace domain. 

After processing in the time domain, Fourier transformation, phasing and basic processing (calibration, peak picking, integration) ahs been performed, additional processing steps to improve spectral quality are at your disposal. This includes operations common to both ID and 2D spectra e.g. baseline correction in the frequency domain, as well as operations specific to these different type.s of data sets. 

The preceding analysis views the problem of solving for the sine-wave amplitudes and phases in the frequency domain. Alternatively, the problem can be viewed in the time domain. It has been shown that [Quatieri and Danisewicz, 1990], for suitable window lengths, the vectors a andJ3 that satisfy Equation (9.75) also approximate the vectors that minimize the weighted mean square distance between the speech frame and the steady state sinusoidal model for summed vocalic speech with the sinusoidal frequency vector . Specifically, the following minimization is performed with respect to a andJ3... 

The electronic absorption spectra of complex molecules at elevated temperatures in condensed matter are generally very broad and virtually featureless. In contrast, vibrational spectra of complex molecules, even in room-temperature liquids, can display sharp, well-defined peaks, many of which can be assigned to specific vibrational modes. The inverse of the line width sets a time scale for the dynamics associated with a transition. The relatively narrow line widths associated with many vibrational transitions make it possible to use pulse durations with correspondingly narrow bandwidths to extract information. For a vibration with sufficiently large anharmonicity or a sufficiently narrow absorption line, the system behaves as a two-level transition coupled to its environment. In this respect, time domain vibrational spectroscopy of internal molecular modes is more akin to NMR than to electronic spectroscopy. The potential has already been demonstrated, as described in some of the chapters in this book, to perform pulse sequences that are, in many respects, analogous to those used in NMR. Commercial equipment is available that can produce the necessary infrared (IR) pulses for such experiments, and the equipment is rapidly becoming less expensive, more compact, and more reliable. It is possible, even likely, that coherent IR pulse-sequence vibrational spectrometers will... 

PSOLA which operates in the time domain. It separates the original speech into fi-ames pitch-s5mchronousfy and performs modification by overlapping and adding these fi ames onto a new set of epochs, created to match the synthesis specification. 

We specify the desired performance of a closed-loop system by specifying its desired (ideal) output complementary sensitivity function, T, which relates the reference signal, r, and the output signal, y, in the one degree of freedom (DOF) control configuration ( see Fig. 1 ). For the SISO case, a classical approach is to map time-domain specifications such as settling time, rise time, maximal overshoot, and steady-state error into the parameterization of a transfer function of the form... 

This relationship provides an alternative method to determination of the concentration of the analyte of interest. Specifically, lifetime or decay time measurements can be used in fluorescence based sensors to determine the analyte concentration. These measurements provide better results than steady-state measurements. Time-domain lifetime measurements are typically performed by exciting the sensing element with a short optical pulse which is much shorter than the average fluorophor lifetime. For a single population of fluorophors, the rate at which the intensity decays over time can be expressed as ... 

Performing ESR experiments with pulsed instead of continuous irradiation provides great flexibility for designing experiments that can be adapted to specific problems. In general, such time-domain experiments can be used to distinguish between different types of spin relaxation and to separate the various... 

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