Robust reliability analysis

Using the quantified uncertainty obtained from Bayesian methods, there are two important types of applications. The first category is robust reliability analysis. Under severe earthquake excitations, buildings and bridges may exhibit significant nonlinear behavior. With a stochastic representation of the anticipated ground motions [96,130,237], one important reliability problem is to determine the first passage probability of some response quantities of interest in a... 

The aforementioned methods can be applied to evaluate the reliability of engineering systems subjected to stochastic input with a given mathematical model. On the other hand, if a parametric model of the underlying system is available and the probability density function of these parameters is obtained by Bayesian methods, the uncertain parameter vector can be augmented to include the model parameters and the uncertain input components. Then, robust reliability analysis can proceed for stochastic excitation with an uncertain mathematical model. This allows for more realistic reliability evaluation in practice so that the modeling error and other types of uncertainty of the mathematical model can be taken into account. 

Sections above discuss typical chromatographic methods applied to TA samples. Beside sufficient separation, sensitive and selective detection is also required for robust and reliable analysis. The following section is addressed to different ionization interfaces, mass analysers and scan modes allowing valuable LC-MS method design. 

Major technological and scientific innovation in the past 10 to 15 years has significantly broadened the applicability of Raman spectroscopy, particularly in chemical analysis. Fourier transform (FT)-Raman, charge-coupled device (CCD) detectors, compact spectrographs, effective laser rejection filters, near-infrared lasers, and small computers have contributed to a revolution in Raman instrumentation and made routine analytical applications possible. An increase in instrumental sensitivity by factors as large as 10, plus decreases in both interferences and noise resulted from this revolution. The number of vendors of Raman spectrometers increased from 3 to 12 over a 10-year period, and integrated commercial spectrometers led to turnkey operation and robust reliability. 

The main snag with universal detectors such as FID or TCD is the lack of selectivity needed for sensitive trace analysis in complex matrices. If, however, the analytical system incorporates efficient sample pretreatment and the adequate separation of the compounds of interest from interfering compounds in the matrix, these universal detectors become very attractive because of their robustness, reliability, low cost, and ease of use. ... 

The final goals of pesticide analyses are to obtain the cleanest possible samples, to determine the minimum possible concentration with the lowest limits of detection, and to avoid pesticide degradation during transfer to the laboratory. All this means that the accuracy and precision of a method for pesticide analysis will be directly dependent on the sample preparation procedure used. This operation is the most time-consuming and labor-intensive task in the analytical scheme. In response to the need for effective, robust, reliable sample preparation, a number of procedures have developed for fast, simple, and, if possible, solvent-free or solvent-minimized operation. Most such procedures, both conventional and new, are used for the analysis of pollutants in air, water, soils, sediments, and biota. ... 

For example, in reliability analysis, the quantity Q is considered as the probability that the structure with parameter vector 0 would fail, i.e., Q(0) = P(F 0, C). Then, the updated integral becomes the updated robust probability of failure for the structure, when it is subjected to some stochastic excitation [198] ... 

For obtaining reliable analysis results, the (high-performance) thin-layer chromatographic (TLC) method should he validated before using it as a quality control tool. The validation parameters that should he evaluated are stability of the analyte, specificity/selectivity, linearity, accuracy, precision, range, detection limit, quantification limit, and robustness/ruggedness. 

In this subsection, we will discuss noise sources that arise from the nanopore itself, Erec, and the head stage during nanopore sensing. For the noise analysis, we use the simplified electrical models shown in Figure 29.3. Here, and model the resistance and capacitance of the nanopore, respectively. These vary with nanopore diameter, thickness, and material. Erec is modeled by the series resistance and a double-layer capacitance Cj, where R is much smaller than Rj. Note that in this chapter, we pay attention to the resistive-feedback transimpedance amplifier (TIA) due to its simple hardware structure and robust reliability, rather than a capacitive-feedback TIA, which requires a disruptive periodic reset [12,15]. Readers who are interested in the capacitive-feedback TIA can refer to the paper of Kim et al. [17]. 

A physically-based RWO model in combination with robust methods for reliability analysis could be applied in real time or near-real time risk assessment. A possible scenario would be an aircraft approaching an airport and getting gradually better information on uncertain factors like lan[Pg.2041]

In section Structural Model the structural model is presented. Time-variant reliability analysis of oscillators is presented in section Time-Variant Reliability of Oscillators. The robust optimization problem and a robustness measures are introduced in section Robust Optimization Problem. Numerical examples are presented in section Numerical Examples, in order to illustrate the importance of taking into account tmcer-tainties in the optimum design of TMD systems. For the sake of simpbcity and to focus on the formulation of the robust design optimization problem, the numerical analysis section deals with one TMD only. It should be remarked, however, that the extension to MTMD is straightforward. The chapter is finished with a Summary in section Summary. 

For all systems important to safety, the degree of redundancy, diversity, testability and robustness should be justified as being adequate to achieve the required reliability of the safety functions to be performed by the systems. This demonstration may be based on a balance of deterministic criteria and quantitative reliability analysis. 

For a method to be useful it must provide reliable results. Unfortunately, methods are subject to a variety of chemical and physical interferences that contribute uncertainty to the analysis. When a method is relatively free from chemical interferences, it can be applied to the determination of analytes in a wide variety of sample matrices. Such methods are considered robust. 

Major drivers for using micro-channel chip systems for chemical analysis are low reagent consumption, low energy consumption, high reliability, good robustness also in the hands of personnel not trained in analytical chemistry, and low maintenance requirements [30]. 

There is little doubt on the basis of the above review that speleothems are useful in an extremely wide range of applications and the frequency of publications devoted to speleothem-based archives is increasing rapidly. Fundamental to all applications is a robust and high-precision chronology and uranium-series techniques currently set the standard in this regard for speleothems. Reliable ages can be obtained for most samples where material appears to be well-preserved. However, it will become increasingly important to demonstrate reliability as the spatial resolution of analysis improves further. 

The robustness of an analytical method can be defined as a measure of the capability of the method to remain unaffected by small, but deliberate, variations in method parameters. The parameter therefore provides an indication of the method reliability during normal usage. The ruggedness of a method is the degree of reproducibility of test results obtained by the analysis of the same samples under a variety of conditions, such as different laboratories, different analysts, different instruments, different lot of reagents, different days, etc. 

If the scope of mass spectrometry is limitless, why are the applications of clinical MS almost completely small molecules The answer is that most clinical tests analyze small molecules, biomarkers that are either metabolites or steroids and, hence, mass spectrometers would target those first. Perhaps a more complete answer would also include that methods must be very robust, easily reproduced in different labs, reliable, and subjected to an extensive array of validation tests. Although peptide and protein analysis is increasing rapidly in clinical labs, the MS approaches to these assays is lagging behind somewhat. MS techniques targeting these peptides and proteins exist, but they are primarily in the research stage, with few systems and methods subjected to the clinical rigors of validation. Once the necessary validations occur and methods simplified, it will only be a short time before MS is used routinely in clinical proteomics. 

The Xenopus oocyte can reliably express LGIC receptors. In our laboratory, we have seen robust expression of the Torpedo nAChR, 5-HT3 receptors and various GABAa receptor subtypes in oocytes. Injection of cRNA transcripts is a convenient and reproducible way to achieve the expression levels needed for functional analysis of receptor subtypes. We have found that functional characterization with this system complements biochemical experiments conducted on native receptors or those that have been expressed in mammahan cells. A combination of these approaches is essential for furthering our understanding of structure-function relationships in these receptors. 

Reliable quality control in the field of pharmaceutical analysis is based on the use of valid analytical methods. For this reason, any analytical procedures proposed for a particular active pharmaceutical ingredient and its corresponding dosage forms shonld be validated to demonstrate that they are scientifically sonnd nnder the experimental conditions intended to be used. Since dissolntion data reflect drng prod-net stability and quality, the HPLC method used in snch tests shonld be validated in terms of accuracy, precision, sensitivity, specificity, rngged-ness, and robustness as per ICH guidelines. 

For the above-described reasons, molecular spectroscopic techniques have become the most common choices for pharmaceutical analysis in addition to chromatography. The latter, however, are being gradually superseded by the former in some industrial pharmaceutical processes. Recent technological advances have led to the development of more reliable and robust equipment. The ubiquity of computers has enabled the implementation of highly powerful chemometric methods. All this has brought about radical, widespread changes in the way pharmaceutical analyses are conducted. 

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