Measurement of performance

Before we can explore how reactor conditions can be chosen, we require some measure of reactor performance. For polymerization reactors, the most important measure of performance is the distribution of molecular weights in the polymer product. The distribution of molecular weights dictates the mechanical properties of the polymer. For other types of reactors, three important parameters are used to describe their performance ... 

The resist must have suitable radiation sensitivity. Today s exposure tools are so costiy that tool throughput is a key measure of performance. The overall time to expose a resist film is the sum of the times to load and position the substrate in the exposure tool, to align the substrate and the mask, to irradiate the film, and to unload the complete part. In the optimum case the resist exhibits sufficient radiation sensitivity so that the fraction of the overall cycle apportioned to irradiate the film does not limit the number of substrates exposed in a given period of time. 

Computer codes are used for the calculational procedures which provide highly detailed data, eg, the Ruby code (70). Rapid, short-form methods yielding very good first approximations, such as the Kamlet equations, are also available (71—74). Both modeling approaches show good agreement with experimental data obtained ia measures of performance. A comparison of calculated and experimental explosive detonation velocities is shown ia Table 5. 

Eor LEDs utilized in visible/display appHcations, the human eye serves as the detector of radiation. Thus a key measure of performance is luminous efficiency which is weighted to the eye sensitivity (CIE) curve. The relative eye sensitivity, V (L), peaks in the green at A 555 nm where it possesses a value of 1.0. It drops sharply as the wavelength is shifted to the red or blue, reaching a value of 0.5 at 510 and 610 nm. The luminous efficiency, in units of Im/W, of an LED is given by equaton 11 ... 

The RISC versus CISC conundmm has led to the much abused and ultimately extremely confusiag term MIPS (millions of iastmctions per second). Measures of performance that can be more directiy related to a computer s abiUty to perform usehil work should always be preferred over machine MIPS. The throughput of a computer is a function of the number of iastmctions to be executed, the average number of iastmctions that can be executed per clock cycle, and the time per clock cycle. 

Peiformance. Depending on the application, accuracy, repeatability, or perhaps some other measure of performance is appropriate. Where closed loop control is contemplated, speed of response must be included. 

Measurement of Performance The amount of useful work that any fluid-transport device performs is the product of (1) the mass rate of fluid flowthrough it ana (2) the total pressure differential measured immediately before and after the device, usually expressed in the height of column of fluid equivalent under adiabatic conditions. The first of these quantities is normally referred to as capacity, and the second is known as head. 

The disadvantage is that volumetric efficiency is usually much less than conventional trays or packed contactors. Applications are usually limited to cases when only a few transfer units or a single eqiiihbriiim stage is required. Since many of these applications tend to be in heat-transfer sei vice, the following discussion will be in terms of thermal properties and thermal measures of performance. 

The assembly analysis stages 3 and 4 have the following measures of performance... 

The evaluations cited in the following sections are examples of the use of various measures of performance. 

Action planned or taken to stop something from recurring. Acceptance standards based on qualitative measures of performance. 

Keep the presentation focused on the integration project do not be drawn into discussions on particular strengths or weaknesses of the existing systems. If possible, illustrate expected improvements using existing measures of performance. Where performance measures do not exist, propose them, and propose to define the existing level of performance in order to measure future improvement. 

Better measurement of performance. A common frustration in PSM and ESH is that end-of-pipe measurement is all that is available and it is too late to correct a problem once the incident has occurred. Quality Management requires that we seek out in-process measures and leading indicators of performance that will warn of potential problems before they exhibit themselves as incidents. 

The assessment should also seek out systems for measuring performance. Remember that there is a need to measure both PSM and ESH performance, as well as the effectiveness of the processes in place. It is likely that at least some PSM and ESH performance measures will be in place, such as injury rates, number of incident investigations, regulatory infractions and insurance premiums. Your questions should probe for issues that managers track, but perhaps only informally, that could provide new measures of performance. 

Quality records A critical element in improving performance is establishing measurements of performance which can subsequently be analyzed to identify opportunities for improvement. ... 

Measurement of performance. Quality Management requires that measures of performance be established for every activity. These measures include end-of-pipe measurement, such as amounts of material released into the environment or injury rates, and in-process measures of how efficiently you are managing, such as time to review safety improvement proposals or total resources expended on PSM. Each team should be required to identify potential performance measures for the processes they are developing and the activities these processes manage. Many of the end-of-pipe measures will already exist these should be critically examined to ensure that they truly measure performance and are not unduly influenced by other factors. For example, the number of accidents in a fleet of road vehicles is almost directly dependent on the number of miles driven with no improvement in performance, a reduction in miles driven would reduce the number of accidents. 

There are two ways in which the measurement system is likely to be used. The first is to compare the baseline before integration to whatever progress has been made at a given point in time. The second is as a longer term measure of performance of the integrated systems. 

Only retain existing measures beyond a few months where they are genuinely useful measures of performance. 

As described in the previous chapter, Quality Management requires that measures of performance be established. These measures are intended to be used to monitor quality and improvement in performance. 

Capital investments can also be selected on the basis of other measures of performance such as return on investment, internal rate of return, and benefit-cost ratio (or savings-to-investment ratio). Flowever, care must be taken in the application of these methods, as an incremental analysis is required to ensure consistent comparison of mutually exclusive alternatives. Also, rather than requiring a separate value to be calculated for each alternative, as in the case of the life-cycle cost method, these other methods incorporate the difference between two mutually exclusive alternatives within a single measure. For example, the net benefits measure directly pressures the degree to which one alternative is more economically desirable than another. 

The effect on the process of a change in operation of the mixer system (impeller, baffles, etc.) is the final measurement of performance. Thus, operations such as blending, uniform particle suspension, reaction, gas absorption, etc., may be acceptable under one physical system and not so to the same degree under a slightly modified one. The ratio per unit volume on scale-up must be determined experimentally. 

Furthermore, if productivity is considered as a measure of performance, mentoring can also add to this component. Consider, for example, the experience of Tegwin Pulley, director of diversity and staffing services for Texas Instruments (TI) in Texas. He maintains that H s mentoring for new hires initiative has substantially improved the productivity amongst this employee group because mentoring enables them to understand more quickly how to go about their jobs (Tyler, 1998). 

Solution Some measures of performance based on xylene as the limiting... 

When trade-offs exist, no single compound will stand out uniquely as the optimum drug for the market, ranked hrst on all measures of performance. Rather, a set of compounds will be considered that, on current knowledge, span the optimal solution to the problem. These compounds are those for which there is no other compound that offers equivalent performance across all criteria and superior performance in at least one. In multicriteria decision analysis (MCDA) terminology, they are known as Pareto-optimal solutions. This concept is illustrated by the two-criteria schematic in Figure 11.3. 

The nature of the performance metric, y, is determined by the characteristics of the specific process under analysis. Since we are particularly interested in analyzing situations where y is related to product or process quality, it is quite common to find systems where a categorical variable y is chosen to classify and evaluate their performance. This may happen due to the intrinsic nature of y (e.g., it can only be measured and assume qualitative values, such as good, high, and low ), or because y is derived from a quantization of the values of a surrogate continuous measure of performance (e.g., y = good if some characteristic z of the product has value within the range of its specifications, and y= bad, otherwise). 

Our search procedures represent a departure from the above type of paradigm. Rather than simply accepting and implementing a decision policy found by DUg, that optimizes an overall measure of performance, the infimal subsystems and corresponding plant personnel play an active role in the construction and validation of solutions. One tries to build a consensus decision policy, Xpp, validated by all subsystems, DU , k = I,..., K, as well as by the whole plant, DUg, and only when that consensus has been reached does one move toward implementation. Within this context, the upper-level decision unit, DUg, assumes a eoordination role. 

The microautoclave solvent activity tests measure coal conversion in a small batch reactor under carefully controlled conditions. The tests are described as Kinetic, Equilibrium and SRT. The Kinetic and Equilibrium Tests measure coal conversion to tetrahydrofuran solubles at conditions where conversion should be monotonically related to hydrogen transfer. The Kinetic Test is performed at 399°C for 10 minutes at an 8 to 1 solvent to coal ratio. The combination of high solvent ratio and low time provide a measure of performance at essentially constant solvent composition. The measured conversion is thus related to the rate of hydrogen donation from solvent of roughly a single composition. In contrast, the Equilibrium Test is performed at 399°C for 30 minutes at a 2 to 1 solvent to coal ratio. At these conditions, hydrogen donors can be substantially depleted. Thus performance is related to hydrogen donor... 

Strictly, the useful life of a product can only be measured directly by service trials or tests on the complete product. Most assessments of lifetime of plastics are made by considering some measure of performance and specifying some limit or threshold value for the property, which is taken as the end point corresponding to where the material is no longer usable. 

This small study provided useful impressionistic data in addition to objective measures of performance. Cmducting more elaborate field tests with LSD did not seem feasible, however. It remained for the British, three years later, to carry out a realistic military exercise in which trained commandos attempted to defend their position against an enemy platoon. Details of that interesting study are described in a later chapter. 

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