Compensator method

The compensation schemes shown in this book are the most common methods. Several of these will work in each applications, but only one for each is considered the optimum method insofar as the dc gain and closed-loop bandwidth aspects are concerned. Tables B-1 and B-2 will help match a possible compensation method with your application. 

The first step in determining the component values for this compensation method is to determine the inherent dc gain of the power stages. The calculation should be performed with the maximum value of the input voltage, since this is where the system will have its widest exhibited bandwidth. This is done using Equation B.12. 

This compensation method now exhibits a -180 degree phase lag at low frequencies, then beginning at one-tenth the error amplifier s Alter pole (/ep) the phase lag increases to its high frequency limit of -270 degrees. 

Experiments were performed in tlie SIMULAR calorimeter using the power compensation method of calorimetry (note that it can also be used in the heat flow mode). In this case, the jacket temperature was held at conditions, which always maintain a temperature difference ( 20°C) below the reactor solution. A calibration heater was used to... 

FIGURE 35.41 Effect of the cross axes setting compensation method on the clearance in the total width of the calender roll in working condition. 

Both the Bourdon and spiral gauge can be used with a compensation method or with direct observation of the movement of the... 

Quantitative XRF analysis has developed from specific to universal methods. At the time of poor computational facilities, methods were limited to the determination of few elements in well-defined concentration ranges by statistical treatment of experimental data from reference material (linear or second order curves), or by compensation methods (dilution, internal standards, etc.). Later, semi-empirical influence coefficient methods were introduced. Universality came about by the development of fundamental parameter approaches for the correction of total matrix effects... 

In the null-point instruments use is made of the well-known compensating method according to Poggendorf, by which the emf of the cell under test is compared with that of a standard cell. The circuit diagram of such a method54 is illustrated in Fig. 2.14. 

The EMF of a galvanic cell is a thermodynamic equilibrium quatity. Thus, the potential of a cell must be measured under equilibrium conditions, i.e. without current flow. The measured EMF must be compensated by a known external potential difference. The measurement of the EMF of a cell is thus based on determination of a potential difference that exactly compensates the measured potential difference so that no current passes. This is easily achieved by the Poggendorf compensation method (see Fig. 3.13). 

In a chemical plant, time delay is usually a result of transport lag in pipe flow. If the flow rate is fairly constant, the use of the Smith predictor is acceptable. If the flow rate varies for whatever reasons, this compensation method will not be effective. 

The just described compensation method for the parasitic birefringence of windows and polarizing prisms is also useful with respect to the parasitic birefringence created by reflections from the cylinder walls. As has been pointed out, the disturbance caused by the windows is compensated at its maximum. This means, as the test fluid possesses an extinction angle of 45°, that the extinction positions of the window birefringence are oriented parallel and perpendicular to the direction of flow (i.e. the... 

Y chromosomes.244 245 Apparently because of the differing ratios of X A in the two sexes, organisms utilize a variety of dosage compensation methods. In cells of human females only one X chromosome is active. 

Wahbi et al. [32] used a spectrophotometric method for the determination of omeprazole in pharmaceutical formulations. The compensation method and other chemometric methods (derivative, orthogonal function, and difference spectrophotometry) have been applied to the direct determination of omeprazole in its pharmaceutical preparations. The method has been validated the limits of detection was 3.3 x 10 2 /ig/ml. The repeatability of the method was found to be 0.3-0.5%. The linearity range is 0.5-3.5 /ig/ml. The method has been applied to the determination of omeprazole in its gastro-resistant formulation. The difference spectrophotometric (AA) method is unaffected by the presence of acid induced degradation products, and can be used as a stability-indicating assay method. 

With the appearance of the valve voltmeter (or vacuum tube electrometer) in 1935 (see - Beckman) the compensation method has been gradually displaced from everyday laboratory practice [iv], and nowadays almost exclusively electronic voltmeters equipped with transistors and integrated circuits are being used. 

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