共查询到20条相似文献,搜索用时 78 毫秒
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利用铸渗技术试制球磨机衬板,研究不同干燥温度及硼砂作黏接剂对铸渗质量的影响。结果表明,砂型干燥温度的高低,其铸渗层质量存在明显差异;硼砂的黏接性满足铸渗实验要求。通过铸渗层断口质量对比和组织微观观察及硬度测试,分析干燥温度与铸渗层气孔形成之间的关系及硼砂在铸渗过程中的作用,确定方案改善铸渗层质量。 相似文献
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蒸发器加盖观测方法及其效果研究 总被引:1,自引:0,他引:1
大雨和强风常常造成蒸发量缺测,采用蒸发器加盖观测方法能有效地防止蒸发量缺测。文章分别阐述了气象台站在配备专用雨量器和不配专用雨量器两种情况下,蒸发器加盖观测方法及蒸发量的计算方式。 相似文献
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The metal flow in the extrusion process is an important factor in controlling the mechanical property of the extruded products. It is, however, difficult to predict the metal flow in three-dimensional extrusion of complicated sections due to the difficulty in representing the geometry of the die surface and in expressing the corresponding velocity field. In this study a new kinematically admissible velocity field for a generalized three-dimensional flow is derived, in which the flow is bounded by the die surface expressed by an analytic function. Then, by applying the upper-bound method to the derived velocity field, the flow pattern as well as the upper-bound extrusion pressure are obtained. As a computational example, extrusion of clover sections from round billets is chosen. A new method of die surface representation is proposed by which there is a smooth transition of die contour from the die entrance to the die exit. Computation is carried out for work-hardening materials such as aluminium and steel. The analysis takes into account the effect of product shape complexity, lubrication condition and reduction of area on extrusion pressure, average effective strain and distribution of effective strains on the cross-section of the extruded product. 相似文献
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目的 :探讨对复发性鼻窦炎鼻息肉采用修正性鼻内镜手术(Revision endoscopic sinus surgery,RESS)配合激素综合治疗的临床效果。方法 :观察我院2011年10月—2014年10月43例复发性鼻窦炎鼻息肉患者接受RESS及激素治疗的疗效及12个月并发症发生率,比较术前、术后6个月VEGF、COX-2阳性率变化。结果 :43例患者总有效率为93.0%,术中出血量为(216.53±57.14)m L,术后6个月VEGF、COX-2阳性率均显著下降,与术前比较差异有统计学意义(P<0.05)。结论 :对复发性鼻窦炎、鼻息肉采用修正性手术关键在于系统规范的治疗方案及术中对解剖位置的掌握,手术后长期系统综合治疗可降低VEGF及COX-2表达,降低复发率。 相似文献
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Nonlinear elasticity of rectangular elastomeric seals and its effect on elastohydrodynamic numerical analysis 总被引:1,自引:2,他引:1
Elastomeric seals used in high-pressure hydraulic systems obey complex stress–strain laws when sufficiently strained, which occurs for high sealed pressure and large temperature differentials. Such seals often operate in extreme environments of pressures up to 35 MPa (5000 lb/in.2) and temperatures in the range of −60 to +140 °C. For the elastohydrodynamic numerical analysis of these seals, it is imperative that the rubber behaviour under stress is properly described with a suitable stress–strain model, such as the popular Mooney–Rivlin model. Such a nonlinear model is developed and tested in this study to produce important numerical results for the seal performance (contact pressure and width, film thickness, leakage rate and friction). The nonlinear model is then compared with the classic Hookean model of linear elasticity in order to establish the differences of the models and the limits of applicability and validity of each one for a wide range of operating conditions. 相似文献
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为解决目前滤棒干燥技术存在的不足,降低干燥温度,提高干燥效率,将真空技术应用到滤棒的干燥工艺中,并进行了滤棒的真空干燥试验。试验结果表明:在真空度-0.092Mpa,环境温度50℃~55℃的条件下,三个小时即可实现滤棒的干燥,且干燥后的滤棒各项指标均符合要求。 相似文献
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《International Journal of Mechanical Sciences》1960,1(1):109-120
An elementary method of determining the pressure in plane strain press forging between dies with engravings of small inclination is given. The last part of the paper shows, with the help of an elementary model how to compute the energy needed in forging and the efficiency of the operation. 相似文献
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结构可靠性分析的响应面方法比较研究 总被引:1,自引:0,他引:1
针对隐性功能函数下结构可靠性分析问题,将有限元数值分析(FEM)、响应面方法(RSM)和蒙特卡洛随机模拟(MCS)相结合,实现了隐性功能函数下结构可靠度的计算,其中响应面方法包括多项式响应面法(MRSM)和神经网络响应面法(ANN).以简支梁为例,阐明了该方法的具体实现过程,并以直接MonteCarlo模拟法计算结果作为相对精确解,对不同响应面法支持下的FEM-MRSM-MCS和FEM-ANN-MCS的计算结果进行了对比分析,得出两种响应面法均可满足工程要求,但在泛化能力和精度方面,神经网络响应面均优于多项式响应面,且神经网络响应面可以一次实现从多维空间向另一多维空间的映射,为多失效模式下隐性功能函数下复杂结构的可靠性分析提供了新的思路. 相似文献