Estimating system performance

Table 19.25 Engineering Hours Estimating System Performance...

In most simulation experiments a large number of outputs are generated. They are summarized by a statistic, which is often a sample average of the outputs, denoted Y. The vrdue of the statistic is used to estimate system performance, so statistics are also called estimators. The statistics are functions of the outputs, so they are also completely determined by the random number seeds or streams. 

FVI The FVI quantifies the maximum decrement in MSS reliability caused by the -th system component state deterioration and it also allows estimating system performance level decrease for Ml unreliability of the i-th system component. 

This equation, which is called the Deutsch equation, has been shown to be a useful tool for estimating the performance of electrostatic precipitators. An interesting detail in the Deutsch equation is the exponent, which is equal to the collection efficiency of a laminar flow system. The equations based on laminar flow and turbulent flow can be assumed to be the extreme conditions, and the true situation is somewhere in between these two cases (see Fig. 13.1,5). 

It is probable that a full load cannot be obtained during the final test, for reasons of low ambient or lack of completion of other equipment for the process. In such circumstances, the commissioning engineer must establish the load which prevailed at the time and make an estimate of the system performance, on the basis of time run, or otherwise interpret the figures obtained. In such cases it may be advisable to agree to a tentative acceptance of the plant and carry out a full-load test at a later date. 

Copp and Everet (1953) have presented 33 experimental VLE data points at three temperatures. The diethylamine-water system demonstrates the problem that may arise when using the simplified constrained least squares estimation due to inadequate number of data. In such case there is a need to interpolate the data points and to perform the minimization subject to constraint of Equation 14.28 instead of Equation 14.26 (Englezos and Kalogerakis, 1993). First, unconstrained LS estimation was performed by using the objective function defined by Equation 14.23. The parameter values together with their standard deviations that were obtained are shown in Table 14.5. The covariances are also given in the table. The other parameter values are zero. 

Because borrow soils will be mixed and modified during placement, the cover soil for an ET landfill cover, as constructed, will be unique to the site. However, the soil properties may be easily described. The design process requires an evaluation of whether or not the proposed soil and plant system can achieve the goals for the cover. Numerous factors interact to influence ET cover performance. A mathematical model is needed for design that is capable of (1) evaluating the site water balance that is based on the interaction of soil, plant, and climate factors and (2) estimating the performance of an ET landfill cover during extended future time periods. 

To predict the heat transfer effects, the engineer must have an adequate quantitative description of heat transfer between the tube wall and the fluid phases, heat transfer between the tube wall and the fluid phases, heat transfer between the two phases, the rate of phase change within the system, and the rate of heat transfer resulting from phase change. Unfortunately, present design procedures only provide estimates of the system performance. Many procedures have not been formulated in a systematic manner, and therefore it is difficult to pinpoint areas where the present understanding of the design process is weakest. 

From the design viewpoint, Eq. (78) could be coupled with Eq. (71) to obtain an approximation of the system performance and if the liquid temperature profile can be estimated, the same procedure can be followed with Eq. (80). However, in general the design engineer needs to use analytical expressions for the absolute rates of vaporization and condensation, so that with a knowledge of the rate terms and the other parameters, Eqs. (71) and (72) could be solved for the temperature and mass flow-rate profiles. 

A comprehensive framework of robust feedback control of combustion instabilities in propulsion systems has been established. The model appears to be the most complete of its kind to date, and accommodates various unique phenomena commonly observed in practical combustion devices. Several important aspects of distributed control process (including time delay, plant disturbance, sensor noise, model uncertainty, and performance specification) are treated systematically, with emphasis placed on the optimization of control robustness and system performance. In addition, a robust observer is established to estimate the instantaneous plant dynamics and consequently to determine control gains. Implementation of the controller in a generic dump combustor has been successfully demonstrated. 

In 1995, SEMATECH performed an evalnation of the Alzeta TPU for abating perflnorocom-ponnds (PECs). Based on this evalnation, a cost estimate was performed. While the costs of a commercial-scale remediation system may vary from this estimate, the information is discnssed as a basis for comparison. 

Another 1991 cost estimate was performed by the Bechtel Corporation for the U.S. Department of Energy s (DOE s) Rocky Flats Plant near Boulder, Colorado. Costs were estimated at 40 per 1000 gal for a system in a site with relatively low solar insolation. The estimate was based on a system with a peak water flow of 6.3 liters/sec and an annual treated volume of 8500 gal. The processing costs were dominated by the cost of a system to treat inorganic components of the water (D12953N, p. 203). 

Correlating Factors. One of the principal objectives of the worker in the field of combustion is the development of correlations that will predict or estimate the performance of combustion systems. In recent years a number of factors have been explored, but because of the complexity of the over-all process no exact treatment connecting all the factors has been found. 

Experimental values of the open circuit potential (OCP) measured by linear sweep voltammetry using the newly developed CuCl/HCl electrolyser were found to be consistent with the theoretical thermodynamic calculations. The performed electrolysis tests over wide ranges of temperature demonstrated that the elevated temperatures enhance the system performance. The current efficiency of the CuCl/HCl electrolyser, estimated using the amount of produced hydrogen, at current densities below 100 mA was found to be above 90% for a number of tested commercially available membranes. The current efficiency at current density above 100 mA was reduced mainly due to permeation of Cu through the membranes. 

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)... 

Based on the tank test results, on-board system performance with the developed TiCrVMo has been estimated as in shown in Table 4. Using TiCrVMo alloy combined with high-pressure MH tank, the whole system can store 5kg of hydrogen within 95L and 225kg, which means 0.053kgH2/L and 0.022kgH2/kg as a total system, respectively. 

Table 4. Estimation of on-board system performance with TiCrVMo alloy.

A rigorous performance analysis is the key to a meaningful feasibility study. Performance analysis is essential in estimating system the costs. The design of industrial units, or more accurately, the prediction of industrial plant performance was the primary objective of the cunent work. Both the operating and investment costs, key elements in feasibility studies, were determined on the basis of mass and energy balances. 

Intel OverDrive OverDrive chips boost system performance by using the same clock multiplying technology found in the Intel 80486DX-2 and DX4 chips. Once installed, an OverDrive processor can increase application performance by an estimated 40 to 70 percent. 

A semi-batch cultivation of a Prasinophyceae, Tetraselmis sp.Tt-1, was examined using a SOL scale tubular bioreactor under lamps with a view to estimating its performance. The mean productivity of more than 20g/mVday could be obtained by fixing the flow rate of the culture medium at 0.5m/s, which was the maximum in this apparatus, by drawing a partial medium once in two days, and by adjusting an initial cell concentration to 0.5-1.0g/L. A long-term and stable cultivation for more than two months could be carried out by this system. 

The proposed strategies for stabilization of gas-lifted oil wells are offline methods which are unable to track online dynamic changes of the system. However, system parameters such as flow rate of injected gas and also noise characteristic are not constant with respect to time. An adaptive Linear Quadratic Gaussian (LQG) approach is presented in this paper in which the state estimation is performed using an Adaptive Unscented Kalman Filter (AUKF) to deal with unknown time-varying noise statistics. State-feedback gain is adaptively calculated based on Linear Quadratic Regulator (LQR). Finally, the proposed control scheme is evaluated on a simulation case study. 

In [56] we estimate the performance of metad3mamics for a system consisting of a tetracationic cyclophane (Cyclobis(paraquat-p>-phenylene)g ) and a 1,5-dihydroxy-naphthalene solvated in acetonitrile (see Fig. 5). For this system, which is a simple model for a class of nanomachines [58], we compute the free energy as a function of two collective variables, the distance between the centroids of the cyclophane and the naphthalene and the coordination number of the naphthalene with the atoms of the acetonitrile. This is defined as ... 

Various performance indices have been suggested [54, 53, 149, 20, 148] and several approaches have been proposed for estimating the performance index for SISO systems, including the normalized performance index approach [53], the three estimator approach [175[, and the filtering and correlation analysis (FCOR) approach [115[. A model free approach for linear quadratic CPM from closed-loop experiments that uses spectrum analysis of the input and output data has been suggested [136]. Implementation of SISO loop based CPM tools for refinery-wide control loop performance assessment has been reported [294]. 

The performance of a closed-loop system can be assessed by the settling time, closed-loop deadband, and the variability of the controlled variable evaluated over an extended period of time. The settling time and the closed-loop deadband can be determined using a closed-loop block sine wave test. For a closed-loop block sine wave test, the setpoint for the control loop is applied in the form of a block sine wave, and the amplitude of the block sine wave is varied until the deadband is determined. During these tests, the settling time of the controller can also be estimated. An accurate determination of the variability of a controlled variable generally requires an extended period of operation. An evaluation of the variability based on a short period of time may not be representative of true system performance. 

---