Performance measurement techniques

The methods and techniques, which are used to study and measure performance vary, depending on whether the problem is being identified or the causes determined, although there is a large degree of overlap. Most of these techniques will be familiar to people with a scientific background, especially those who work in R D, for whom identification and analysis of problems is a daily activity. Some of the more commonly used techniques and where they are likely to be of use are listed below. 

Draw a flow chart of the actual process steps. 

Compare the two charts, note differences for potential problems needing resolution. 

Cause and effect diagrams, which are produced after group discussions on the problem, or its effect, involve the production of detailed check lists and a structured brainstorming (see Section C, 1.8.3). Following this process the diagram will become very complex and has the appearance of the skeleton of a fish hence they are often called fishbone diagrams. 

The use of these techniques will generate the data at the start of any improvement process. Once any changes have been implemented the techniques can then be used again to monitor the effects of these changes. Having confirmed the benefits of the change, the methods can be used to chart its progress over a period of time and also to indicate the next area for improvement. The process must be truly continuous if Total Quality is to be achieved. 

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In conclusion, we have presented many microstructural characterization and performance measurement techniques, together with examples of how to use these techniques to improve the performance of OLEDs. Seeing the enormous progress recently, we expect more and more OLED-related products will be used in our daily life. 

Collaboration does not have to end with personnel and departments within an organization. When establishing performance measures, techniques used by other facilities within the company or industry can lend valuable insight into methods already in use. These techniques may be available from the companies or from professional organizations. The positive results from a collaborative effort include minimal duplication of work and a broader perspective of what should be measured as well as the steps involved in collecting and analyzing the information. 

In the near future the technique will be further evaluated using ultrasonic signals from natural defects, e.g., fatigue cracks. The performance measure and the parameter optimization procedure wilt also be refined in order to obtain a computationally efficient implementation, easy to use for a trained operator. 

Statistical Control. Statistical quahty control (SQC) is the apphcation of statistical techniques to analytical data. Statistical process control (SPC) is the real-time apphcation of statistics to process or equipment performance. Apphed to QC lab instmmentation or methods, SPC can demonstrate the stabihty and precision of the measurement technique. The SQC of lot data can be used to show the stabihty of the production process. Without such evidence of statistical control, the quahty of the lab data is unknown and can result in production challenging adverse test results. Also, without control, measurement bias cannot be determined and the results derived from different labs cannot be compared (27). 

Production Controls The nature of the produc tion control logic differs greatly between continuous and batch plants. A good example of produc tion control in a continuous process is refineiy optimization. From the assay of the incoming crude oil, the values of the various possible refined products, the contractual commitments to dehver certain products, the performance measures of the various units within a refinery, and the hke, it is possible to determine the mix of produc ts that optimizes the economic return from processing this crude. The solution of this problem involves many relationships and constraints and is solved with techniques such as linear programming. 

Model discrimination is a procedure for developing a suitable description of the unit performance. The techniques are drawn from the mathematics hterature where the goodness-of-fit of various proposed models are compared. Unfortunately, the various proposed models will usually describe a unit s performance equally well. Model discrimination is better accomplished when raw or adjusted measurements from many, unique operating conditions provide the foundation for the comparisons. 

The continuous methods combine sample collection and the measurement technique in one automated process. The measurement methods used for continuous analyzers include conductometric, colorimetric, coulometric, and amperometric techniques for the determination of SO2 collected in a liquid medium (7). Other continuous methods utilize physicochemical techniques for detection of SO2 in a gas stream. These include flame photometric detection (described earlier) and fluorescence spectroscopy (8). Instruments based on all of these principles are available which meet standard performance specifications. 

For applied work, an optical characterization technique should be as simple, rapid, and informative as possible. Other valuable aspects are the ability to perform measurements in a contactless manner at (or even above) room temperature. Modulation Spectroscopy is one of the most usehil techniques for studying the optical proponents of the bulk (semiconductors or metals) and surface (semiconductors) of technologically important materials. It is relatively simple, inexpensive, compact, and easy to use. Although photoluminescence is the most widely used technique for characterizing bulk and thin-film semiconductors. Modulation Spectroscopy is gainii in popularity as new applications are found and the database is increased. There are about 100 laboratories (university, industry, and government) around the world that use Modulation Spectroscopy for semiconductor characterization. 

Some measures of PSM and ESH performance are easy to identify, establish and track. These include accident rates, effluent tonnages and composition and number of days lost to illness. Almost all of these traditional performance measures are end-of-pipe that is, they measure the output of the management system and allow corrective action only after a failure has occurred. The ideal measurement system identifies potential problems ahead of actual failure allowing corrective action to be taken. This requires using techniques such as audits and hazard assessments. 

Microwave Hall experiments have been performed in our laboratory.16 They have shown that the mobility of charge carriers in semiconductors can be measured quite reliably even if the semiconductors are only available in the form of a powder. The measurement technique itself is relatively complicated and involves, for example, rectangular waveguides, which can be rotated against each other on opposite sides of the sample to monitor the phase rotation. In the two-mode resonator, two modes of... 

All aspects of interferogram and experimental data acquisition and optical test rig control are provided by a computer program that also performs film thickness evaluation. It is believed that the film thickness resolution of the colorimetric interferometry measurement technique is about 1 nm. The lateral resolution of a microscope imaging system used is 1.2 /u,m. Figure 10 shows a perspective view of the measurement system configuration. This is an even conventional optical test rig equipped with a microscope imaging system and a control unit. 

In designing a continuous plant, therefore, it is essential to establish the measurement and control strategy based on an understanding of which critical aspects are indicative of good or poor plant operation, and how deviation of these measurements can be exploited to perform a corrective process control action. Estabhshing suitable on-hne real-time measurement techniques may be a blocker to the implementation of continuous processing. In contrast, implementation of a successful measurement and control strategy may be the enabler for improved product yields and product quahty. 

There are two main uses of a RM calibration and method performance checking. ISO Guide 32 (1997) deals with the use of RMs for calibration purposes. RMs used for calibration purposes are usually RMs prepared by synthetic means. Commonly, the property values of these RMs are known from preparation, and verified by some kind of suitable measurement technique. This can be a technique directly providing a value for a property of interest, or a technique that allows the comparison of the new material against older measurement standards. 

A spin-off of all of these task forces has been the open discussions that have led to improved design considerations and effective use of resources in the conduct of field exposure studies. These task forces have evaluated a variety of exposure measuring techniques, developed study designs for conducting studies, and performed field studies in a uniform and efficient manner. The task force protocols and designs have become models for the industry, having received valuable input and approval from the regulatory community. 

The development and manufacture of organic light-emitting diodes (OLEDs) have demanded the use of the most advanced microstructural characterization techniques and sophisticated performance measurement devices [1-14], In this chapter, we will briefly describe these techniques and devices and review how scientists and engineers utilize them to improve the performance of OLEDs. 

Comparison of the success of different classification methods requires a realistic estimation of performance measures for classification, like misclassification rates (% wrong) or predictive abilities (% correct) for new cases (Section 5.7)—together with an estimation of the spread of these measures. Because the number of objects with known class memberships is usually small, appropriate resampling techniques like repeated double CV or bootstrap (Section 4.2) have to be applied. A difficulty is that performance measures from regression (based on residuals) are often used in the development of classifiers but not misclassification rates. 

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