Performance-based measurements

The team identifies the contaminants of concern and proposes potentially suitable measurement methods. The measurement methods may come from the EPA guidance manuals for analytical methods or from other appropriate sources for standard methods of analysis. Depending on the type of data, Performance Based Measurement Systems (PBMS) may also be used for obtaining physical, chemical, or biological measurements. The PBMS are alternative analytical methods that are developed for a specific analyte or a group of analytes and offer an innovative or a more efficient analytical approach being at the same time more cost-effective than the standard methods of analysis. 

The new approach named Performance Based Measurement Systems is based on the definition of what needs to be done rather than on the definition of how to do it. The... 

US Environmental Protection Agency, Performance Based Measurement Systems, Notice of Intent, Federal Register, October 6, [US Government Printing Office, 1997b]. 

In May 1999 the U.S. Environmental Protection Agency (EPA) released its proposed Tier 2 emission standards for vehicles and gasoline sulfur standards for refineries [5-7]. They mandated the ASTM D 2622 X-ray fluorescence (XRF) method for sulfur determination, and in later announcements D 6428 became the mandatory method for sulfur determination in diesel fuels. Over the years through discussions and litigations, these rules have been modified to the point where alternate test methods can be used instead of only the mandated methods. The alternate methods allowed would be (a) those developed by the voluntary consensus based standards writing bodies, such as ASTM, or (b) industry methods for which data will have to be provided to EPA to establish their correctness under Performance Based Measurement System (PBMS). Discussions between the industty and EPA are ongoing to further define the statistical basis forjudging the available methods acceptance and other related issues. 

The work performance-based measures analyze the workloads from the speed, accuracy, or error rate of the demanded tasks. In some cases, one or two additional tasks are required to the subjects for deeply understanding the avaUabihty of the cognitive resources [Cain, 2007]. 

Given the predominance of the information processing approach to assessing driver behavior, it is worthwhile to briefly describe the main methods that have been developed to measure it. In general three approaches have been used to assess mental task load performance based measures using a secondary task, physiological measures of stress, and subjective evaluations of mental load. 

Few performance-based measures are available and useful for assessing excavation damage prevention programs. Those measures that are maintained are specific to selected States or are maintained by individual companies for a specific underground system. Data concerning underground damage for all types of sys-tans are needed ... 

By comprehensively and routinely using JHA as a tool, performance-based measurements can be established to determine if jobs are correcdy using the proper controls, procedures, and protocols. Performance-based measurements without an understanding of how jobs are completed and accomplished may not be providing a full picture of where problems or issues exist. As a result, the potential to identify loss-producing events can remain hidden from both the employees and the leadership team. 

In many cases, the methods used to solve identification problems are based on an iterative minimization of some performance criterion measuring the dissimilarity between the experimental and the synthetic data (generated by the current estimate of the direct model). In our case, direct quantitative comparison of two Bscan images at the pixels level is a very difficult task and involves the solution of a very difficult optimization problem, which can be also ill-behaved. Moreover, it would lead to a tremendous amount of computational burden. Segmented Bscan images may be used as concentrated representations of the useful... 

In a performance-based approach to quality assurance, a laboratory is free to use its experience to determine the best way to gather and monitor quality assessment data. The quality assessment methods remain the same (duplicate samples, blanks, standards, and spike recoveries) since they provide the necessary information about precision and bias. What the laboratory can control, however, is the frequency with which quality assessment samples are analyzed, and the conditions indicating when an analytical system is no longer in a state of statistical control. Furthermore, a performance-based approach to quality assessment allows a laboratory to determine if an analytical system is in danger of drifting out of statistical control. Corrective measures are then taken before further problems develop. 

One system for measuring catalyst failure is based on two oxygen sensors, one located in the normal control location, the other downstream of the catalyst (102,103). The second O2 sensor indicates relative catalyst performance by measuring the abiUty to respond to a change in air/fuel mixture. Other techniques using temperatures sensors have also been described (104—107). Whereas the dual O2 sensor method is likely to be used initially, a criticism of the two O2 sensors system has been reported (44) showing that properly functioning catalysts would be detected as a failure by the method. 

Manufacturers of measurement devices always state the accuracy of the instrument. However, these statements always specify specific or reference conditions at which the measurement device will perform with the stated accuracy, with temperature and pressure most often appearing in the reference conditions. When the measurement device is apphedat other conditions, the accuracy is affected. Manufacturers usually also provide some statements on how accuracy is affected when the conditions of use deviate from the referenced conditions in the statement of accuracy. Although appropriate cahbration procedures can minimize some of these effects, rarely can they be totally eliminated. It is easily possible for such effects to cause a measurement device with a stated accuracy of 0.25 percent of span at reference conditions to ultimately provide measured values with accuracies of 1 percent or less. Microprocessor-based measurement devices usually provide better accuracy than the traditional electronic measurement devices. 

If the technical staff from the client company recognizes that a toller may be asked to perform new analyses and make operating decisions based upon the results, the client may help the toller develop the needed procedures and skills required to make these decisions. Typically a round robin laboratory qualification exercise will be performed. Samples of known standards and unknown concentrations of the materials to be analyzed for the toll will be prepared and sent to both laboratories. This can help ensure that equipment calibration is synchronized and that the toller is capable of performing accurate measurements. In some cases, the toller may be the party with the chemical, process, or synthesis specific expertise. 

Training is delivered via classroom, on-the-job, computer-based, or self-study programs. Tests and performance observations measure understanding. 

Aircraft and land-based turbines have different performance criteria. Aircraft turbine engine performance is measured in terms of output, efficiency, and... 

The complex structure of the various solutions was investigated by Raman and IR absorption spectroscopy. Containers made of sapphire and KRS-5 were used for Raman and IR spectra measurements, respectively. Vibration spectra analysis was performed based on the band assignment [171, 187] presented in Table 45. 

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

An acid-base titration can be performed without measuring the pH of the solution, if an indicator is present that changes color as the titration passes the stoi-chiometric point. An indicator is a weak organic acid that contains a highly delocalized 7t bonding network. We use p to designate the p of an indicator. At pH < p, ... 

In Section IV we considered a categorical performance metric y. Although that represents a common practice, especially when y defines the quality of a product or process operation, there are many instances where system performance is measured by a continuous variable. Even when y is quality-related, it is becoming increasingly clear that explicit continuous quality cost models should be adopted and replace evaluations of performance based on categorical variables. 

Sangster, J. Octanol-Water Partition Coefficients Fundamentals and Physical Chemistry, Wiley, Chichester, 1997. n Valko, K. Application of high-performance liquid chromatography based measurements of lipophilicity to model biological distribution. J. Chromatogr. A 2004, 1037, 299-310. 

A globally based measurement network for atmospheric Hg does not exist. Longterm measurements of TGHg have, however, been performed at some land-based stations. Data from remote marine sites are mainly available from research cruises. Recently, Slemr et al. (2003) compiled TGHg data from a number of permanent stations and oceanic cruises for the northern and southern hemispheres (Figure 2.7). Although the data set is incomplete, a peak in TGHg concentrations seems to have... 

The present section on ES method and mechanism and MS detection is based on two previous reviews of the subject316,36 and the reader interested in details and additional references in the literature might find these reviews useful. In the present account, we include information aimed at the investigator who is interested in performing physical measurements on ions produced by ES. We became convinced that a minimum of mechanistic information is necessaiy, on the basis of a personal experience. Some years ago, we persuaded a scientific colleague working with molecular beams to try to study ions produced by ES. He was enthusiastic about the possibilities and took off with modifications of his apparatus. Some months later he reported his disappointment. He needed the ions to be in helium gas and tried ES in helium. He saw no ions and gave up. We hope that the present account will show him why he could not observe ions in He and how to go about to obtain ions in helium. 

Moment analysis is one of the simplest types of analysis and is useful for measuring the performance of the chromatography. Moments can be used to measure the same things that are measured in ID chromatographic systems these include the first, second, and third moments, which are more accurate than the related peak maximum, peak width, and peak asymmetry. In 2D, however, these values each have a component in each dimension and this can be easily determined in software-based measurement systems. 

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