基于ERSM涡轮盘径向变形的非线性动态概率分析

为了准确设计高压涡轮盘和叶尖间隙,从概率的角度进行了涡轮盘径向变形的分析。介绍了高精度高效率的非线性动态概率分析的极值响应面方法(Extremum Response Surface Method, ERSM),并建立了其数学模型。考虑材料属性和边界条件的非线性,以及热载荷和离心载荷的动态性,基于ERSM对涡轮盘径向变形进行了非线性动态概率分析,得到了输入输出参数的分布特征和影响涡轮盘径向动态变形的主要因素。最后,通过方法比较,验证了ERSM在保证计算精度的前提下能大大提高计算速度,节约计算时间,改善计算效率。为进行更有效的涡轮盘设计和优化,改善叶尖间隙设计和控制的合理性提供了有效依据。      

光旁路技术研究及应用

光旁路技术是行业的新兴技术,尤其适用于链形及环形网络结构。当处于链形网络中间的某一传输设备因停电停止工作后,光旁路设备会立即切换光路,将该站上游过来的光信号跳过本站,直接送至下游站,从而避免了下游站业务中断。它具有非常积极的学术研究价值及市场价值。     

基于ERSM涡轮盘径向变形的非线性动态概率分析

为了准确设计高压涡轮盘和叶尖间隙,从概率的角度进行了涡轮盘径向变形的分析。介绍了高精度高效率的非线性动态概率分析的极值响应面方法(Extremum Response Surface Method, ERSM),并建立了其数学模型。考虑材料属性和边界条件的非线性,以及热载荷和离心载荷的动态性,基于ERSM对涡轮盘径向变形进行了非线性动态概率分析,得到了输入输出参数的分布特征和影响涡轮盘径向动态变形的主要因素。最后,通过方法比较,验证了ERSM在保证计算精度的前提下能大大提高计算速度,节约计算时间,改善计算效率。为进行更有效的涡轮盘设计和优化,改善叶尖间隙设计和控制的合理性提供了有效依据。      

涡轮机法与凿骨劈冠法在拔除阻生智齿中的临床比较

目的：比较涡轮机去骨拔除法（试验组）与凿骨劈冠拔除法（对照组）在拔除下颌中位和低位阻生智齿时的临床疗效。方法：280颗下颌中位和低位阻生智齿随机分成两组,试验组采用涡轮机去骨拔除法,对照组采用凿骨劈冠拔除法,记录手术时间,观察患者术后疼痛程度、张口受限、颞下颌关节功能紊乱及干槽症发生情况。结果：试验组手术时间、患者术后疼痛程度、颞下颌关节功能紊乱、张口受限及干槽症的发生率均小于对照组,两组间发生率有统计学差异。结论：涡轮机去骨拔除法拔除下颌中位和低位阻生智齿较传统凿骨劈冠法有较多优点,值得临床推广。     

水轮机接力器活塞密封型式的选择分析

主要介绍了铸铁活塞环的计算方法，和组合密封的工作原理。根据水轮机接力器工况条件，分析了在设计时如何合理的选择活塞环。     

对液压传动动力元件中压力瞬变的探讨

液压传动技术中动力元件中压力瞬变现象是液压系统中出现的一种压力波动，这种压力波动产生的振荡如果超过液压结构的安全应力值，将会造成系统元件的损坏，文章讨论了压力瞬变的过程和限制压力波振动的办法，用流体力学原理分析并合理地解决了这一问题。     

大型变截面翼型叶片与气动性能优化分析

基于叶素-动量理论,以输出功率系数为优化目标、叶片的弦长、扭角和相对厚度为设计变量,建立叶片优化设计的数学模型。综合考虑轮毂和叶尖气动损失,对各变截面翼型的弦长和扭角进行了计算和修正。利用Matlab优化工具箱,对大型变截面翼型叶片进行优化的气动性能理论计算。以1.5MW风力机叶片为例,比较了变截面翼型叶片和单一翼型叶片气动性能的计算结果,变截面翼型叶片的气动性能优于单一叶片的气动性能,为风力机叶片外形设计提供参考。     

Optimized frequency-based foundation design for wind turbine towers utilizing soil-structure interaction

This study illustrates design optimization for multiple wind towers located at different villages in Alaska. The towers are supported by two different types of foundations: large mat or deep piles foundations. Initially, a reinforced concrete (RC) mat foundation was proposed. Where soil conditions required it, a pile foundation solution was devised utilizing a 30 in thick RC mat containing an embedded steel grillage of W18 beams and supported by 20-24 in grouted or un-grouted piles. For faster installation and lower construction cost, all-steel foundations were proposed for these remote Alaska sites. The new all-steel design was found to reduce the natural frequencies of the structural system due to softening the foundation. Thus, the tower-foundation system could potentially become near-resonant with the operational frequencies of the wind turbine. Consequently, the likelihood of structural damage or even the collapse is increased.A detailed 3D finite-element model of the tower-foundation-pile system with RC foundation was created using SAP2000. Soil springs were included in the model based on soil properties obtained from the geotechnical investigation. The natural frequency from the model was verified against the tower manufacturer analytical and experimental values. When piles were used, numerous iterations were carried out to eliminate the need for the RC and optimize the design. An optimized design was achieved with enough separation between the natural and operational frequencies. The design successfully avoids damage to the structural system, while eliminating the need for any RC in most cases.     

Endoscopic vein harvest in elective off-pump coronary artery bypass grafting

While traditional open vein harvest was related to postoperative wound complications, endoscopic vein harvest was developed to minimize the morbidity in the greater saphenous vein harvest procedure. In this study, these two procedures were compared for postoperative wound healing and long-term graft patency. We reviewed all consecutive patients undergoing elective off-pump coronary artery bypass grafting from January 2004 to December 2005 and collected data regarding wound complications and coronary events. Wound complications included dehiscence, excessive discharge, edema, altered sensation, cellulitis, hema-toma, pain scale, and superlicial and deep wound infection. Coronary events were defined as diagnosis of myocardial infarction during the first year's follow-up. A total of 392 patients were included in our series, among whom 44 were excluded from the study due to emergent operation, preoperative intra-aortic balloon pump support, or the greater saphenous vein varicose characteristic, 78 belonged to open vein harvest group, and 270 to endoscopic vein harvest group. Wound complications were significantly less in the endoscopic group (5.2%) compared to the open group (19.2%) (P=0.0002). There was no significant difference on preopera-tive risk factors, total operative time, or hospitalization days. During one-year follow-up, both the early and late graft patency rates were similar between the two groups. Endoscopic vein harvest is safe and effective, which carries less risk for wound complica-tions and is associated with better satisfaction and cosmetic result than the traditional greater saphenous vein harvest procedure. The endoscopic vein harvest also demonstrates a great long-term patency.     

650MW核电机组凝汽器单侧冷却下汽机旁排投运分析

本文主要通过对中核运行2厂1/2号650MW核电机组的GCT-C旁排阀及减温减压装置热力过程的介绍,分析在失去一列CRF水时,即凝汽器在失去一列冷却水,在单侧冷却的情况下汽机旁排投运,此时相关热工参数是否仍能满足凝汽器设计要求。