Degradation statistical

Chinnam, R. B. 2002. On-line Reliability Estimation for Individual Components Using Statistical Degradation Signal Models. Quality and Reliability Engineering International, 18 pp. 53-73. 

Starting from Jellinek s equation for statistic degradation of a polymer and applying it to the PET melts, the following relation is arrived at ... 

In matrix composites, the failure is often due to creep rupture. For matrix composites, suitable models should incorporate features such as environmentally driven, statistical degradation mechanisms both in the glass fiber, and in the polymer matrix. Relevant knowledge concerning this special topic has been compiled in the literature (9). 

Evans, M. A statistical degradation model for the service life prediction of aircraft coatings with a comparison to an existing methodology. Polym. Test 31, 46-55 (2012)... 

In the analysis of pumps, IPRDS failure data for 60 selected pumps at four nuclear power plants were statistically analyzed using FRAC. The data cover 23 functionally different pumps, respectively, for two BWRs. Catastrophic, degraded, and incipient failure severity categories were considered for both demand-related and time-dependent failures. 

The specification development process is a data-driven activity that requires a validated analytical method. The levels of data needed include assay precision, replicate process results (process precision), and real-time stability profiles. A statistical analysis of these data is critical in setting a realistic specification. Most often, aggregation and fragmentation degradation mechanisms are common to protein and peptide therapeutics. Therefore, the SE-HPLC method provides a critical quality parameter that would need to be controlled by a specification limit. 

Maximum rate of change alert The second alert (i.e., maximum rate of change alert) is used to automatically notify the operator that based on statistical data the rate of degradation has increased above the pre-selected norm. Since the vibration amplitudes of all machine-trains increase as normal wear occurs, the statistical rate of this normal increase should be trended. A drastic change in this rate is a major indication that a problem is developing. 

Acid anhydrides have been employed with, and without the use of a base catalyst. For example, acetates, propionates, butyrates, and their mixed esters, DS of 1 to ca. 3, have been obtained by reaction of activated cellulose with the corresponding anhydride, or two anhydrides, starting with the one with the smaller volume. In all cases, the distribution of both ester groups was almost statistic. Activation has been carried out by partial solvent distillation, and later by heat activation, under reduced pressure, of the native cellulose (bagasse, sisal), or the mercerized one (cotton linters). No catalyst has been employed the anhydride/AGU ratio was stoichiometric for microcrystalhne cellulose. Alternatively, 50% excess of anhydride (relative to targeted DS) has been employed for fibrous celluloses. In all cases, polymer degradation was minimum, and functionalization occurs preferentially at Ce ( C NMR spectroscopic analysis [52,56,57]). 

Statistical Analysis of Coatings Degradation by Time-Series Methods... 

Scarcely had the covalent chain concept of the structure of high polymers found root when theoretical chemists began to invade the field. In 1930 Kuhn o published the first application of the methods of statistics to a polymer problem he derived formulas expressing the molecular weight distribution in degraded cellulose on the assumption that splitting of interunit bonds occurs at random. 

Equation 8 yielded a fine correlation with rms error of 0.88 kcal/mol a, (3 and y were -0.150, 0.114, and 0.0286, though the ASASA term could be replaced by a constant with little degradation of the fit. Nevertheless, we remained concerned about the size of the data set (it is statistically desirable to have at least 5 data points per descriptor) and slow convergence for the Coulombic energy components. 

Complex 69 was prepared in about 60% yield with about 15% metallation and a small drop in molecular weight (from 73,000 for PMPS to 68,000 for 69), which, allowing for the increase in statistical repeat unit, indicates some degradation. Related model compounds based on the coordination of phenyl rings in phenyltrimethylsilane and 1,2-diphenyltetramethyldisilane were compared with 69. The UV absorption maxima (224 and 337 nm) were almost unchanged from those of the precursor PMPS (223 and 338 nm), which possibly reflects the low metal loading as... 

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