This paper presents a modeling procedure and diagnostic algorithm for fixture related faults in panel assembly. From geometric information about the panel and fixture, a fixture fault model can be constructed off-line. Combining the fault model with inline panel dimensional measurements, the algorithm is capable of detecting and classifying multiple fixture faults. The algorithm, which relies heavily on the fault model, is based on least squares estimation. Consequently, the test is of relatively simple form and is easily implemented and analyzed. Experimental results of applying the algorithm to an autobody assemble process are provided.
The metabolic effects of local tumors on the whole system and the link between the tumor microenvironment and the systemic macroenvironment are poorly known. In this study, we profiled the metabolites in tissues and plasma collected from patients with gastric cancer (GC), postoperative GC patients, and control patients with chronic superficial gastritis (CSG). The tissues and plasma of the GC patients showed distinctly different metabolic phenotypes from those of the CSG controls. Significantly elevated glycolysis, tricarboxylic acid cycle (TCA), and amino acids turnover characterized metabolism of GC tissues; and greater metabolic perturbation were observed in GC tissues than that in GC plasma, both compared with the controls. Remarkably, the levels of the discriminatory metabolites characterizing GC were not positively correlated in tissues and plasmas. For examples, TCA intermediates, lactate, amino acids and free fatty acids were more abundant in the tissues but less concentrated in plasma relative to their CSG controls; while glucose was lower in both the tissues and plasma of GC patients than the controls. For the first time we showed a balance profile of metabolites between tumor microenvironment and the systemic environment. Additionally, the surgical removal of the GC tissue restored the levels of the molecules cited above to different extent in postoperative GC patients, indicating the relationship of systemic environment to tumor microenvironment. The results further suggested that metabolomic analysis of intact tissues is potentially an alternative technique for the clinical diagnosis of GC.
A stochastic model of aging is developed in terms of accumulation and expression of intracellular lesions caused by environment or intrinsic genetic program. In contrast to the commonly used Gompertz-Makeham approach to the parametric analysis of mortality data, the model yields a hazard function that is bounded from above. For testing the model in experiments aimed at studying animal longevity, a Kolmogorov-type statistical test is presented with regard to the hypothesis involving unknown parameters. Examples concerning longevity of intact animals of two different species, as well as the effect of a prolonged irradiation at a low dose rate, are given to illustrate the model application and goodness-of-fit testing. The results of the analysis of published data show that the rate of lesion formation is not sustained at a constant level throughout life, though in some cases its variations with age can be considered negligible.
The present paper is the first to propose a minimum stress criterion for the minimum dimensional variation during sheet metal assembly. The weld sequence affects the dimensional variation owing to the welding process. A case study illustrates the minimum stress criterion on dimensional variation. This paper proposes a generic design criterion for sheet metal products and processes that would produce minimal stress-induced dimensional variation for spot-welded sheet metal assemblies. The process design proposes a minimum strees build-up by using the ‘sheet metal ironing welding technique’ in the weld sequencing design. The product design proposes a minimum stress build-up design criterion to manage the accumulation of stress. The proposed product and process design methods enable automotive body design engineers to create a quality product with minimum dimensional variation caused by the manufacturing stress within the body-in-white structure. Moreover, this facilitates the industry's objective of building a high quality automotive body with minimum stress. This is an important factor in contributing to the superior quality of the body panel fits. It also helps to reduce the quality-related warranty costs. This paper primarily focuses on the development of a joint design guideline by exploring the relationship between the dimensional variation and the stress build-up. First, the automotive assembly process design will be introduced. A simple analysis of a one-dimensional assembly is produced. A three-dimensional structural analysis of a box assembly is investigated for the effect of stress build-up within a structure on the dimensional instability or variation. Then a three-dimensional finite element analysis of an assembly with weld sequencing of two imaginary parts is produced. An experimental industrial trial has confirmed the validity of the simulation methodology. Then a welding sequence design guideline is produced based on the previous simulation result, followed by a joint design guideline to help improve the design of dimensionally robust design.
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