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991.
《Energy and Buildings》2004,36(8):855-863
The EnergyPlus building energy simulation software has been tested using the IEA HVAC BESTEST E100–E200 series of tests. The volume 1 final report for the International Energy Agency (IEA) solar heating and cooling programme task 22 building energy simulation test and diagnostic method for heating, ventilating, and air conditioning equipment models (HVAC BESTEST) was recently published in January 2002. HVAC BESTEST is a series of steady-state tests for a single-zone DX cooling system. Cases range from dry to wet coil, low to high part load, and low to high temperatures. This published test suite includes three sets of analytical solutions and results from several other simulation programs for comparison.This test suite was initially used to test EnergyPlus beginning with beta versions prior to its official public release, and it is also applied as an ongoing quality assurance test. The application of these tests proved to be very useful in several ways:
- •revealed input model shortcomings, which resulted in new user inputs being added;
- •revealed reporting errors which were fixed;
- •revealed algorithmic errors which were fixed;
- •revealed algorithmic shortcomings which were improved or eliminated through the use of more rigorous calculations for certain components;
- •in later versions, caught newly introduced bugs before public release of updates.
992.
993.
《International Journal of Pressure Vessels and Piping》2004,81(4):327-336
A series of numerical procedures have been presented recently for the integrity assessment of structures based upon the Linear Matching Method. A typical example of a holed plate has been used to verify these procedures for the evaluation of plastic and creep behaviours of components. In this paper, a more complex 2D tubeplate at the outlet from a typical AGR heat exchanger is analysed for the shakedown limit, reverse plasticity, ratchet limit and creep relaxation based on the application of the Linear Matching Method for a thorough case study. Both a constant material yield stress and a temperature-dependent yield stress are adopted for the evaluation of the ratchet limit. For the evaluation of accumulated creep strains, flow stresses and elastic follow-up factors with differing dwell times at the steady cyclic state, a monotonic creep computation is performed, where the start-of-dwell stress is the rapid cycle creep solution at the beginning of the dwell period. An estimation of the tubeplate lifetime is then obtained by the evaluation of fatigue and creep endurances. 相似文献
994.
《Composites Science and Technology》2004,64(13-14):2207-2212
Finite Element Analysis is used to examine contact damage induced by Hertzian indentation of a porcelain coating on a glass-filled polymeric substrate. Different forms of cracking in the porcelain coating are studied –“Hertzian” cone cracks close to the indenter, more distant “outer” cone cracks, and “radial” cracking at the coating/substrate interface. The effects of porcelain coating thickness and radius of curvature on the critical stresses for initiation of these cracks are examined. The predicted critical load curves suggest that for systems with compliant substrates (relative to the coating) with a given radius of curvature, there is an optimum porcelain coating thickness that maximises the critical load for cone cracking. Conversely, for a given coating thickness, the effects of curvature vary significantly – for thinner coatings, where outer cone cracks are dominant, highly convex surfaces are more resistant to cracking, whereas for thicker coatings, which are more prone to Hertzian cone cracking, concave surfaces produce a higher predicted critical load. Curvature is observed to have little effect on the critical load for the formation of radial cracks, which remains the dominant mode of failure in cases of thin coatings on compliant substrates. 相似文献
995.
996.
For the optimal position problems of the three-point supporting machine tools, a optimal method was proposed to optimize the locations of the three-point supporting. The detailed design processes were introduced with a T-shaped bed of a CNC cylindrical grinder which was taken as the research object. Firstly, the initial supporting positions were determined by the method of dividing bottom plane of the bed and finding the centroid of each region, and the pad-iron positions were parameterized, then the parameter ranges were specified according to the position limit conditions. Secondly, the multi-objective optimization mathematical model of pad-iron positions was established, and the optimal solution was obtained to achieve the optimal static and dynamic performances of the bed. Finally, by analyzing the relationship between the three pad-iron positions obtained from Pareto frontier and the bed geometric sizes, the arrangement rule of three-point support for this model was obtained. The results show that the static and dynamic performances of the bed are improved by this suggested method. 相似文献
997.
998.
相位恢复算法一直存在着精确度不高,收敛速度慢甚至停滞不前等问题。将基于光强传输方程(TIE)法与G-S迭代算法混合提高了相位恢复的精确度,梯度算法的提出加大了迭代步长,使得收敛速度加快。采用GS-TIE算法和振幅加成梯度算法分别从仿真和实验的角度去比较分析恢复的效果。通过对二维图像仿真得出,振幅加成梯度算法在收敛速度上是GSTIE迭代算法的3倍,精确度是GS-TIE迭代算法的10倍。从实验结果得知,GS-TIE恢复的相位清晰可见,轮廓明显,在边缘处过度均匀,而振幅加成梯度算法相对比较模糊,在轮廓边缘处过度不均匀,悬差较大。 相似文献
999.
1000.