Operating point analysis

DC Operating Point Analysis DC Small-Signal Transfer Function DC Sweep Analysis Sensitivity Analysis AC Analysis... 

Add UIC (Use Initial Conditions) to the. TRAN statement. This statement causes SPICE to bypass the DC operating point analysis. Initial conditions should be placed on capacitors at their expected operating voltage. Just as with the use of incorrect nodesets, incorrect initial condition values can produce incorrect solutions or nonconvergence. Results should be verified for validity. 

SPICE tip SPICE automatically precedes the AC and transient analyses with two operating point analysis, one for AC and one for the transient. The operating point values are used to set the biasing for the AC analysis and the initial starting point for the transient analysis. For the AC analysis the operating point analysis is often called the small signal bias solution. 

AES analysis is done in one of four modes of analysis. The simplest, most direct, and most often used mode of operation of an Auger spectrometer is the point analysis mode, in which the primary electron beam is positioned on the area of interest on the sample and an Auger survey spectrum is taken. The next most often used mode of analysis is the depth profiling mode. The additional feature in this mode is that an ion beam is directed onto the same area that is being Auger analyzed. The ion beam sputters material off the surface so that the analysis measures the variation, in depth, of the composition of the new surfaces, which are being continu-... 

One of the first things you should do when you are simulating an amplifier circuit is to check the transistor operating point. If the transistor bias is incorrect, none of the other analyses will be valid. If another analysis does not make sense, check the operating point. When PSpice finds the bias point, it assumes that all capacitors are open circuits and that all inductors are short circuits. 

Do not use steps 3-5 of the DC convergence solutions. Using these steps may not produce a valid DC operating point, which is essential for SPICE to linearize the circuit. See the AC analysis description. Once DC convergence is achieved, the AC analysis will also converge. 

The zero-point analysis characterizes the rotor hydraulics in two ways. First, the zero-point value gives the liquid flow rate over the more-dense-phase weir just as the liquid in the separating zone rises to the edge of the less-dense-phase weir. Second, the slope of the curve above the zero point measures the liquid rise over the more-dense-phase weir relative to the liquid rise over the less-dense-phase weir. Thus, if all rotors in a set have about the same zero point and the same slope above the zero point, then they can all be expected to operate about the same in two-phase flow. 

Based upon this analysis the designer may decide either to change the configuration or to change the operating point. 

At the time the analysis was undertaken) information on the system performance was available for only one operating point and cost information consisted of initial installation costs plus estimates of life times. Equipment costs were not related to operating conditions. Under these circumstances only the accounting approach could be used. The available information is summarized in Table II. (For more details, see reference 10)... 

From the previous analysis, we conclude that a robust plantwide control structure will fix the combined isobutane + recycle (Fj) and fresh butene flow (F0), as illustrated in Figure 9.4. The desired production rate and selectivity could be achieved in a 3-m3 reactor, operated at 268 K. The operating point shows low sensitivity to errors in the manipulated variable Fj (Figure 9.5). This design seems to ensure feasible operation even if the temperature decreases to 260 K (Figure 9.6) or the catalyst activity becomes 40% of the initial value (Figure 9.7), irrespective of the purity of the butene feed stream (Figure 9.8). 

From eqn. (10), it can be seen that the narrower the aperture the better the SNIR will be. However, the experiment time in single point analysis varies inversely with aperture time and in scanned operation it varies inversely with the square of the aperture time. Thus, for example, in order... 

What are the control implications of this analysis The first conclusion is that autothermal systems (no furnace) have two or more steady states. There is also a good chance that the normal operating point corresponds to the intermediate steady state that is open-loop unstable. This is certainly the case when the reactor is operated at less than 100 percent conversion. 

In eontrast to these unstable operating points, consider what would happen to the reaetor temperature if a reaetor operating at were subjeeted to very small temperature fluctuations. From Figure 8-24 we observe that a pulse increase in reaetor temperature would make the heat of removal greater than the heat of generation [thei (r) curve would be above the G(T) eurve] and the temperature would drop back down to Tj 2 If a small pulse deerease in the reactor temperature oecurred while the feed temperature remained eonstant at Tq, we would see that the curve G(T) would be above the heat-removed eurve R(T) and the reaetor temperature would eontinue to rise until was again reaehed. A similar analysis could be carried through for reaetor temperatures r,, . . s4>... 

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