Critical characteristic

Microelectrodes with several geometries are reported in the literature, from spherical to disc to line electrodes each geometry has its own critical characteristic dimension and diffusion field in the steady state. The difhisional flux to a spherical microelectrode surface may be regarded as planar at short times, therefore displaying a transient behaviour, but spherical at long times, displaying a steady-state behaviour [28, 34] - If a... 

Refers to the number of orthogonal axes on which the critical characteristics lie, and which cannot be achieved by processing from a single direction. 

The critical characteristic on each component was analysed, calculated from the analysis and the value obtained was plotted against the process capability indices, Cpk and Cp, for the characteristic in question. See Appendix V for descriptions of the 21 components analysed, including the values of Cp and Cp from the SPC data supplied. Note that some components studied have a zero process capability index. This is a default value given if the process capability index calculated from the SPC data had a mean outside either one of the tolerance limits, which was the case for some of the components submitted. Although it is recognized that negative process capability indices are used for the aim of process improvement, they have little use in the analyses here. A correlation between positive values (or values which are at least within the tolerance limits) will yield a more deterministic relationship between design capability and estimated process capability. 

Once the variability risks, and q, have been calculated, the link with the particular failure mode(s) from an FMEA for each critical characteristic is made. However, determining this link, if not already evident, can be the most subjective part of the analysis and should ideally be a team-based activity. There may be many component characteristics and failure modes in a product and the matrix must be used to methodically work through this part of the analysis. Past failure data on similar products may be useful in this respect, highlighting those areas of the product that are most affected by variation. Variation in fit, performance or service life is of particular interest since controlling these kinds of variation is most closely allied with quality and reliability (Nelson, 1996). 

The characteristic was analysed using CA and q was found to be 9. The values of (/m = 9 and S = 8 are found to intersect on the Conformability Map above the 10% isocost line. (If they had intersected between two isocost lines, the final isocost value is found by interpolation.) If there is more than one critical characteristic on the component, then the isocosts are added to give a total isocost to be used in equation 2.15. The total failure cost is determined from ... 

Figure 4 Spacer component showing a critical characteristic, X...

Lucas PLC 1994 Identification and Elimination of Critical Characteristics. Engineering and Design Procedures, No. QP219, Lucas Automotive Electronics, Solihull. 

TABLE II. CRITICAL CHARACTERISTICS OF SOY PROTEIN PRODUCTS FOR USE IN INJECTION OR ABSORPTION PROCESSES... 

The catalytic performances of the supported catalysts clearly demonstrated the improvement in terms of activity or selectivity by such optimized catalytic systems. This improvement is related to a nanometer control of the critical characteristics of the active sites. Enhancement of the catalytic performances and the understanding of structure-reactivity relationships can only be achieved by advancing the understanding of different preparation methods, eventually leading to better control over the characteristics of the active sites at a nanometer scale. Moreover, new properties of these solids may be found, which could have a great impact on catalytic reactions. 

Each analytical procedure should include the appropriate system suitability tests defining the critical characteristics of that system. Other parameters may be included at the discretion of the applicant. 

The basic principle of the method is simple. A cohort of patients with the disease in question is identified, and then a cohort of patients without the disease (usually two to three times as many) is matched with respect to a number of critical characteristics and used as the control group. Differences between the two groups with respect to exposure to the suspected causative agent are then measured. A major advantage is that uncommon or rare conditions are accessible to study, which is not the case for cohort studies or for computerised systems, where the total number of patients available is less than the several millions that might be needed. 

Austin et al., 1995 Hellwich and Schubert, 1995). Clearly, the octamller system is inadequate to account for certain critical characteristics of biological membranes, which are comprised of... 

The certification/validation of excipients used in solid oral dosage forms is also extremely important [23]. Excipients can represent less than 1% of a tablet formula or as much as 99%. It is no less important to validate the critical characteristics of the 1% material than of an excipient used in larger quantities. Factors to be aware of are (1) the grade and source of the excipients, (2) particle size and shape characteristics, and (3) lot-to-lot variability. 

Fig. 8.1. A key idea in chemometrics is to record K variables (including spectral data) for S samples to form a matrix S X K. The critical characteristics of both the samples and the spectral data can then be understood using a smaller set of matrices S x M and M x K while the unmodeled residual remains available for analysis as the matrix e. While the reduced matrices provide insight into the system or process, residual data can be used to understand errors or limitations of the model...

LEFM, for fractures occurring in the elastic domain, leads us to characterize the materials using critical characteristics for crack initiation (or arrest in the case of stick-slip propagation). 

The most critical characteristics of a fuel processor are the following ... 

Refining engineers and chemists are most interested in the ease of desulfurizing petroleum using thermal and thermocatalytic treatments. The sulfur is removed primarily as hydrogen sulfide. Thermal and thermocatalytic studies have established that non-thiophenic sulfur (aliphatic as in thiols, acyclic and cyclic sulfides) evolve H2S much more readily than thiophenic sulfur (aromatic heterocyclic compounds). Thus, the relative abundances of nonthiophenic (aliphatic) and thiophenic (aromatic) sulfur is a critical characteristic for all fuels with respect to ease of desulfurization. Analytical methods were developed in the 1960s for classifying the total sulfur in crude... 

HDPE composite has critical characteristics concerning tribological behaviour. Johnson et al. (55) also confirmed that the addition of nanotubes to HDPE decreases the wear rate of the composites. Table 5.8 shows average wear rates and the decrease in wear rates... 

While there appears to be some agreement between the observed and theoretical iron oxide solids settling velocities, the observed silicon oxide values appear to be several times greater than expected. This difference in behavior of the silicon oxide and iron oxide slurries cannot be accounted for by density effects. Since the ratio of the density of iron oxide and silica is 2.ll+, the predicted VgT for an iron oxide would be 3.8 times greater than for silica, Further work is needed to determine the critical characteristics of a solid that are important in governing its settling velocity. 

A critical characteristic of energetic materials is the Chapman-Jouguet (CJ) state. This describes the chemical equilibrium of the products at the end of the reaction zone of the detonation wave before the isentropic expansion. In the classical ZePdovich-Neumann-Doring (ZND) detonation model, the detonation wave propagates at constant velocity. This velocity is the same as at the CJ point which characterizes the state of reaction products in which the local speed of sound decreases to the detonation velocity as the product gases expand. 

When assessing the impact of industrial discharges on receiving waters, the most critical characteristics are ... 

Unfortunately, the universality implied in Eqs. (2.3.12) and (2.3.13) is not well satisfied experimentally. As we shall see in Chapter 7, this situation arises because the van der Waals equation of state does not reproduce the critical characteristics of fluids satisfactorily. Other equations of state in common use suffer from similar defects. As will be shown later, a completely different approach must be employed to characterize the properties of fluids near criticality. 

U.S. President Jimmy Carter authorizes study leading to the Global 2000 report. This report recognizes biodiversity for the first time as a critical characteristic in the proper functioning of the planetary ecosystem. It asserts that the robust nature of ecosystems is weakened by species extinction. 

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