Measurements importance

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 ... 

Batch processes can be synthesized by first synthesizing a continuous process and then converting it to batch operation. The process yield is an important measure of both raw materials efficiency and environmental impact. 

H, for which J = 0, is the intrinsic coercivity whereas the usual coercivity, for which S = 0, is denoted by H or H. For permanent magnets, the value (BH), the maximum energy product, is an important measure of quaHty. The value (BH), iadicated ia the secoad quadrant of Figure 1, represents the poiat of maximum efficieacy where a givea amouat of magnetic flux is produced by the smallest amouat of material. 

Flow is an important measurement whose calibration presents some challenges. When a flow measurement device is used in applications such as custody transfer, provision is made to pass a known flow through the meter. However, such a provision is costly and is not available for most in-process flowmeters. Without such a provision, a true cahbration of the flow element itself is not possible. For orifice meters, calibration of the flowmeter normally involves cahbration of the differential pressure transmitter, and the orifice plate is usually only inspected for deformation, abrasion, and so on. Similarly, cahbration of a magnetic flowmeter normally involves cahbration of the voltage measurement circuitry, which is analogous to calibration of the differential pressure transmitter for an orifice meter. 

Serial Interfaces Some very important measurement devices cannot be reasonably interfaced via either analog or pulse inputs. Two examples are the following ... 

The most important measures to reduce stray currents are ... 

A number of risk importance measures have been defined for the interpretation of PSAs and for use in prioritization of operational and safety improvements. Some of these measures are similar to sensitivity defined as the total derivative (equation 2.8-1). 

Inspection Importance is Fussell-Vesely Importance with the risk set to 1. sc crtil other importance measures called "worths."... 

Importance measures the contributions of various components to the probability of failure in the form of a cutset equation (Section 2.2). A cutset equation has the form of a products of probability. As such it is linear in the probabilities. 

The sequences involving the i-th component may be separated from the other sequences and this probability factored from the sum of products as shown in equation 2.8-9, where is the cutset with factored out. This property relates the importance measures. Substituting equation 2.8-9 into equation 2.8-2 gives equation... 

The relationships between the importance measures is based on the assumption that the systems are not reconfigured in response to a component outage. If this is done, the basic definition of the importance measure is still valid but there is not such a simple relationship. Disregarding this complication, some interpretations of the importances may be made. The Bimbaum Importance is the risk that results when the i-th system has failed (i.e., it is the A, term in Equation 2.8-9). Inspection Importance and RRWI are the risk due to accident sequences containing the i-th system. Fussell- Vesely Importance is similar except it is divided by the risk so may be interpreted as the fraction of the total risk that is in the sequences contains the Q-th system. The Risk Achievement Worth Ratio (RAWR) is the ratio of the risk with system 1 failed to the total risk and is necessarily greater than one. The Risk Achievement Worth Increment (RAWI) is the incremental risk increase if system 1 fails and the Risk Reduction Worth Ratio (RRWR) is the fraction by which the risk is reduced if system 1 were infallible. 

Importance - calculates and displays three importance measures, Fussell-Ve.scly, Risk Reduction Ratio, Risk Increase Ratio, for each event in the system, sequence, or end state. 

Different types of importance measures to represent the results, and... 

Ki-.k H.ised Regulation EQUIMP calculates component importance measures based on f rnups uC h,.i. K events, RDUPDATE perform.s sensitivity on entire Llasse.s of cvetiis Tivj-.c and other tools produce results to support a risk-b.iscd aiguincni lot coilv relief... 

Having completed the risk analyses, computed the uncertainties, and identified critical systems by importance measures (which also identifies valuable systems improvements having low costs), the PSA results must be presented. An executive summary compares the risk of operations that were analyzed with the risks of similar operations. It identifies and explains the main contributors to the risk to people untrained in PSA and statistical methods. Figure 6.3-5 shows two pie-charts that show the risk contributions of various initiators for PWRs and BWRs. A chart similar to one of these would be an effective way of showing the risk contributions in simplified form. 

The next level of presentation is a technical summary that gives details of the risks including the system s importance measures systems, effects of data changes, and assumptions that are critical to the conclusions. It details the conduct of the analysis - especially the treatment of controversial points. The last level of presentation includes all of the details including a roadmap to the analysis so a peer can trace the calculations and repeat them for verification. 

IMPORTANCE - Accepts the output from BUILD and calculates importance measures (Section 2.8) and provides input for the uncertainty analysis. 

One important measurement made by geochemists is the Total Organic Carbon (TOC) measurement. The results are expressed as a weight percentage. When the TOC is less than 0.5 percent, the rock is considered unlikely to have enough kerogen to produce oil or gas. 

An important measure for quality is the verification by MD or SA of the stability of a molecular model. Other programs (e.g., PROCHECK) can also be used to check the globular geometrical quality of a structure to avoid serious defects in the geometry of proteins. 

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