不同模量比对复合材料储能飞轮强度的影响

以材料的环向与径向模量比λ作为参量,利用ANSYS有限元分析软件,对给定尺寸不同材料的单层及双层异构复合材料飞轮转子进行强度计算,得出飞轮转子在高速旋转时的径向和环向应力分布规律。进而利用强度比方程求解各种结构的强度比,分析材料参数对飞轮转子强度的影响。     

1000MW水轮发电机不对称运行时阻尼条涡流损耗计算分析

针对大型水轮发电机不对称运行时阻尼条易熔断的现象,在建立电机二维电磁场-电路-运动耦合时步有限元模型的基础上,对一台1000MW水轮发电机不对称运行时阻尼条涡流损耗进行深入研究.全面考虑了定子开槽、磁极转动以及定子电流等因素对阻尼条涡流损耗的影响,准确计算出不同运行工况下一个磁极内各根阻尼条涡流损耗,分析其变化规律,并在此基础上讨论了阻尼系统连接方式、阻尼条半径、阻尼条材料对阻尼条涡流损耗的影响.研究结果表明,不对称运行时,沿旋转方向最后一根阻尼条涡流损耗最大,阻尼系统结构参数对阻尼条中涡流损耗分布有较大影响.     

Synthesis and properties of the modification of micro-crystal LiMn2−x Al x O4 cathode material for Li-Ion batteries

The micro-single crystal material spinel LiMn2-xAlxO4 was prepared by a sol-gel procedure and modified by alumina; the electrochemical measurements show that the performances and characteristics of modified LiMn2-xAlxO4 electrode material are better than those of LiMn2O4. Hence, the modified LiMn2-xAlxO4 is a good cathode material for lithium batteries. This can be explained that the size of the modified particle is larger than that of unmodified material, so electrons can be easily transported between the particles.     

Effect of heat treatment on the mechanical properties of FeCoZrWB bulk metallic glass

A Fe61Co10Zr5W4B20 bulk metallic glass (BMG) with a diameter of 2 mm was prepared by using copper mould suction casting. The X-ray diffraction (XRD), differential scanning calorimetry (DSC), micro-hardness and compression tests were adopted to investigate the structure, thermal stability, especially, the effect of heat treatment on the micro-hardness and compression strength of this BMG. The BMG exhibits micro-hardness of about 1 207 Hv and compression fracture strength of about 1 707.6 MPa. After being annealed below the onset of crystallization temperature, the micro-hardness almost keeps constant. But after being annealed above the peak of crystallization temperature, the micro-hardness increases firstly and then declines gradually with the elongation of annealing time. However, annealed for the same period of time, the micro-hardness will increase with the rise of annealing temperature, while the compression fracture strength will apparently decrease.     

单纯手法复位与手法复位加敏使朗口服治疗良性阵发性位置性眩晕疗效分析

目的 比较单纯手法复 位 和 手 法 复 位 加 口 服 抗 眩 晕 药 治 疗 后 半 规 管 良 性 阵 发 性 位 置 性 眩 晕（PC ？BPP V ） 的疗效。方法 将2004 年1 月～2011 年6 月期间收治的236 例 BPP V 患 者 随 机 分 为 两 组, 对 照 组 112 例采用单纯手法复位, 治疗组124 例在手法复位基础上加敏使朗口服, 两组均于治疗后1 周和3 个月时复查, 比较其疗效。结果 治疗后1 周时, 对照组和治疗组的有效率分别为86 .61 % 和89 .52 % , 治疗后3 个月时对照组有效率92 .86 % （104／112 ） , 治疗组有效率为93 .54 % （116／124 ） , 两者比较差异均无统计学意义（P ＞0 .05 ） 。结论 单纯手法复位法和手法复位加口服抗眩晕药物治疗 BPP V 疗效相当。     

竹塑复合材料在宁夏灌区末级渠系 衬砌中的应用研究

宁夏灌区末级渠系渠道衬砌率低,冻胀破坏和渗漏损失严重,灌区农业灌溉水利用系数仅为0.42。而且,灌区末级渠系的衬砌改造一直全部采用混凝土刚性材料进行防渗,存在的问题较多。为此,引进了技术先进、价格合理、适应性强的竹塑复合材料进行末级渠系衬砌,以改善灌区输水条件,延长衬砌工程使用寿命,实现水资源高效利用。本文从水力条件、节水效果、耕地占用、维修养护、施工速度等方面对传统混凝土渠道与竹塑复合材料衬砌渠道的特性进行了分析比较,并进行了相关综合经济效益评价。     

堆石混凝土的应用现状与发展趋势

介绍了堆石混凝土的概念、施工工艺和分类,阐述了堆石混凝土的应用现状,论述了堆石混凝土的应用前景及发展趋势,指出堆石混凝土是一种新型的环保节能的施工材料,具有广阔的应用前景。     

《胶结颗粒料筑坝技术导则》亮点 解读与思考

近期即将出台的《胶结颗粒料筑坝技术导则》（以下简称《导则》）,是水利部第一次规范性指导堆石混凝土及胶凝砂砾石发展的技术性文件,必将对堆石混凝土技术发展体系的构建起到标杆的作用,对推进我国环保节能型社会发展具有重要意义。本文就《导则》中关于堆石混凝土技术的一些要点做些解读,并就技术在推广应用中应注意的问题提出建议。     

某网络设备EMC 测试超标的分析和结构优化

某设备带插卡EMC测试中辐射超标,文中从插卡PCB和机箱导槽的电容耦合效应入手,分析了EMC测试超标的原因,通过在机箱导槽和PCB之间设计一个铍铜弹性夹片零件,增强了PCB的单板地和机箱之间的电气连接可靠性,从而有效减少了电磁波的电容耦合效应,解决了EMC测试超标问题。同时运用有限元分析方法并进行样品实物测试对比,分析了该铍铜弹性夹片零件在实际生产应用中出现的夹持不可靠问题的原因,并通过更换合适的铍铜材料型号和选择正确的热处理方式解决了该零件的夹持不可靠问题。     

MRT letter: Human bloodstains on antique aboriginal weapons: a guiding low-vacuum SEM study of erythrocytes in experimental samples on ethnographically documented biological raw materials

The aboriginal use of reed and bone as raw materials for knives and daggers, respectively, has been well-documented ethnographically in some geographical areas of Melanesia. Because of the significant role that these weapons played in inter- and intra-ethnic aggression, they can potentially have retained smears from the contact with human blood. To carry out a guiding low-vacuum scanning electron microscopy (SEM) study of specific interest to ethnography, the outsides of a fragment of stalk of giant cane (Arundo donax) and tibial diaphysis of domestic sheep (Ovis aries) were smeared with peripheral human blood. No biological specimen preparation was applied to the samples. After just over 1 month, bloodstain boundaries and their neighboring inner areas were examined via secondary electrons by a variable-pressure SEM (VP-SEM) working in low-vacuum mode. On both substrates, bloodstains exhibited micro-scales. No janocyte (erythrocyte negative replica) was observed in the examined areas. However, erythrocytes were seen crowded together as grain-shaped corpuscles in the smear on reed, and several hecatocytes (moon-like shaped erythrocytes) were evidenced in the smear on bone. The results of this study suggest that a VP-SEM working in low-vacuum mode can be used fruitfully to detect blood remains in medium-sized reed and bone antique aboriginal artifacts. This procedure can prospectively help to ethnographic museum curators and aboriginal-art surveyors as an easy guiding test in the valuation of antique traditional weapons prior to acquisition, when the real use of a piece has been claimed by the supplier.