A CEC-funded project has been performed to tackle the problem of producing an advanced Life Monitoring System (LMS) which would calculate the creep and fatigue damage experienced by high temperature pipework components. Four areas were identified where existing Life Monitoring System technology could be improved:
1. 1. the inclusion of creep relaxation
2. 2. the inclusion of external loads on components
3. 3. a more accurate method of calculating thermal stresses due to temperature transients
4. 4. the inclusion of high cycle fatigue terms.
The creep relaxation problem was solved using stress reduction factors in an analytical in-elastic stress calculation. The stress reduction factors were produced for a number of common geometries and materials by means of non-linear finite element analysis. External loads were catered for by producing influence coefficients from in-elastic analysis of the particular piping system and using them to calculate bending moments at critical positions on the pipework from load and displacement measurements made at the convenient points at the pipework. The thermal stress problem was solved by producing a completely new solution based on Green's Function and Fast Fourier transforms. This allowed the thermal stress in a complex component to be calculated from simple non-intrusive thermocouple measurements made on the outside of the component. The high-cycle fatigue problem was dealt with precalculating the fatigue damage associated with standard transients and adding this damage to cumulative total when a transient occurred.
The site testing provided good practical experience and showed up problems which would not otherwise have been detected. 相似文献
Among the photocathodes used for particle identification based on the Cherenkov Ring Imaging technique, the TMAE molecule is still the best in terms of quantum efficiency. Despite the fact that TMAE gaseous photocathodes have already been used in a number of large experiments, one still seeks answers to many detailed questions. We present a systematic study of gaseous photocathodes based on TMAE mixed with helium, hydrocarbon and CF4-based gases at normal pressure. The study includes a measurement of the electron drift velocity, gas quenching properties, single electron pulse height spectra and anode wire aging. The paper makes recommendations for carrier gas mixtures to obtain the best quenching, and suggests how to manage TMAE wire aging. This study was motivated by a specific particle identification detector proposal, the Fast Drift CRID proposed for the B-factory at SLAC. 相似文献
Cardiac papillary fibroelastomas are unusual, frond-like growths typically found on cardiac valves, diagnosed incidentally on autopsy or cardiac surgery, but rarely during life. We report a rare case of an aortic valve papillary fibroelastoma detected by transthoracic echocardiography and confirmed by histologic study. 相似文献
For flexible manufacturing of short production runs where a large variety of product sizes, component types, and surface reflectance characteristics are encountered, it is desirable to build flexible computer-controlled systems for feeding parts into machine tools or assembly processes that combine maximum flexibility and reliability with minimum cost and cycle-time. This is not a general bin-picking problem; the parts are assumed to be propositioned approximately in totes/pallets/kits with regularly spaced locations. This article presents a machine vision technique based on the principle of retroreflective vision sensing for part-presentation. Since retroreflective material has a distinctive surface reflectance that is not commonly found in natural or man-made objects, the use of retroreflective surfaces enables reliable high object-to-background contrast images to be obtained for a wide variety of objects. Unlike conventional machine vision techniques, which rely on the variance of the surface reflectance of the objects to generate detailed images, retroreflective vision sensing aims at generating a reliable two-dimensional digital object silhouettes so that the location and orientation of the part can be reliably determined. Two application examples, machine loading and assembly, are illustrated. 相似文献
Introduction
Owing to long-time running, more facilities including stations, pipelines, vessels have become corrosive and aged ,some process has grown old, it has exert more burden for the maintenance and repair.Simultaneously, the fluid production rate, oil production rate and water injection rate has changed greatly so that the inflicts and problems from the established surface systems will become more obvious. Energy cost of production and running has increasing continuously. Capacity has been unbalance in systems and areas.
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The objective of this study is to evaluate the potential for recovering fluorocarbons as measures for the abatement of global warming. In this study, we focused on the three different kinds of fluorocarbons: CFCs, HCFCs and HFCs, and targeted refrigerant use because of the availability of relevant data. We first estimated future fluorocarbon emissions from the targeted appliances; we next compared those emissions in the units of CO2 equivalent to the level of CO2 emissions in 1990 from a quantitative point of view. As the result of this study, it was found that fluorocarbon emissions in 1999 and 2010 would be equal to approximately 7 and 3% of the level of CO2 emissions in 1990 respectively. Moreover, if we implement a 100% recovery rate in every recovery route, we can reduce a large amount of emissions which correspond to approximately 2–5% of the level of CO2 emissions in 1990, even if we take into account the energy-related CO2 emissions by the transportation and decomposition of fluorocarbons. 相似文献