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191.
通过文献资料研究方法,对如何培养普通高校音乐教学中大学生的乐感进行探讨分析。在教学实践中学生乐感的培养,主要是通过提升学生的音乐欣赏能力,鉴赏水平,以及听唱练习等方法,发展学生的思维想象能力,提高学生的音乐感受能力和音乐理解水平,培养学生高尚的音乐情操以及对音乐的感知能力。音乐素养的提升是培养大学生音乐感知能力的有效途径和手段,大学生只有不断提升自己的素养,才能深刻、全面、准确的建立自己的音乐感知能力。  相似文献   
192.
It has been well known that nozzle end-clearances in a Variable Nozzle Turbine (VNT) are unfavorable for aerodynamic performance, especially at small openings, and efforts to further decrease size of the clearances are very hard due to thermal expansion. In this paper, both the different sizes of nozzle end-clearances and the various ratios of their distribution at the hub and shroud sides were modelled and investigated by performing 3D Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) simulations with a code of transferring the aerodynamic pressure from the CFD results to the FEA calculations. It was found that increasing the size of the nozzle end-clearances divided equally at the hub and shroud sides deteriorates turbine efficiency and turbine wheel reliability, yet increases turbine flow capacity. And, when the total nozzle end-clearances remain the same, varying nozzle end-clearances’ distribution at the hub and shroud sides not only shifts operation point of a VNT turbine, but also affects the turbine wheel vibration stress. Compared with nozzle hub clearance, the shroud clearance is more sensitive to both aerodynamic performance and reliability of a VNT turbine. Consequently, a possibility is put forward to improve VNT turbine efficiency meanwhile decrease vibration stress by optimizing nozzle end-clearances’ distribution.  相似文献   
193.
办好高校校报离不开一支高素质的学生记者队伍,这既是办好校报的重要条件,也是高校人才培养的需要。在阐述学生记者队伍建设的内涵和现实意义的基础上,从学生记者队伍的选拔、培养、管理等方面,论述了加强学生记者队伍建设的主要举措。  相似文献   
194.
因超高的理论能量密度,锂空气电池在航空航天、电动汽车等领域展示了广阔的应用前景,但其目前的性能仍与实际使用需求有较大的差距。本文旨在开发具有双功能催化作用的正极催化剂以提升锂空气电池的性能。采用简易的一步溶剂热法成功制备了花状结构的SnS_2微球,并首次探究了其作为可充锂空气电池正极催化剂的应用前景。结果表明:所制备的花状SnS_2微球对锂空气电池的正极过程具有优异的催化性能,大大改善了以其为催化剂的锂空气电池的综合性能,证明SnS_2是一种有潜力的、值得深入研究的锂空气电池用催化剂材料。  相似文献   
195.
A high friction coefficient and a low wear rate of contacted surfaces are essential elements to friction pairs between the stator and the rotor in ultrasonic motors. It has been shown that surface textures have a significant effect on improving the tribological performance of friction pairs.In this paper, microgroove arrays are introduced to the stator surface for improving the tribological performance of friction pairs between the stator and the rotor in ultrasonic motors. Microgrooves were fabricated on a phosphor bronze surface by through-mask electrochemical micromachining(TMEMM). Parameters, namely, the electrolyte inlet pressure, applied voltage, pulse duty cycle,and frequency, were varied to investigate their influences on the dimensions and morphology of the microgrooves. Results showed that the width and depth of the microgrooves were strongly affected by the applied voltage and frequency, while the morphology of the microgrooves was dependent on the electrolyte inlet pressure and the pulse duty cycle. Compared with a smooth surface, the friction coefficient increased from 0.245 to 0.334 and less abrasion was obtained when a surface was textured with microgrooves of which the width and depth were 185.6 and 57.6 lm,respectively. Microgroove arrays might play an important role in enhancing the performance of ultrasonic motors.  相似文献   
196.
Study on Multi-Rotary Joints Space Power Satellite Concept   总被引:1,自引:0,他引:1  
The Space Power Satellite(SPS) would be a huge spacecraft capturing the power of solar radiation in space and to supply electric power to the electric grid on the ground. The SPS concept was proposed by Dr. Peter Glaser in 1968. SPS have been studied now for exactly fifty years by many scientists in various countries. It has been regarded as one of the most promising energy projects of the future and has been attracting more attention in recent years. More and more Chinese scholars and experts are paying attention to the development of SPS. Due to the huge size, immense mass and high power of such a satellite system, there are many technical difficulties which exist to realize SPS. In this paper, recent SPS research and development activities are reviewed first. Various SPS concepts are analyzed and compared. The primary scheme of the Multi-Rotary joint SPS(MR-SPS) is described. The main feature is that the huge solar array comprising many separate small solar sub-arrays and each solar sub-array has two middle power rotary joints. So, the most challenging technology, the high-power rotary joint, is simplified by using many middlepower rotary joints hence the possibility of a single-point failure of a single rotary joint is avoided. This enables easy assembly of the modular solar arrays. Finally some key technologies of MR-SPS are analyzed.  相似文献   
197.
针对目前网站建设维护方面存在的问题,通过对重构方法的介绍及实现步骤的说明,提出了合理进行网站重构的几种方法,给出在网站重构过程中的一些建议.  相似文献   
198.
国际企业年金制度正在从现收现付制向基金积累制转型,从单一的国家养老金向基本养老金、企业年金和个人养老储蓄金相结合的三支柱模式转型,从政府集中统一管理模式向企业年金投资模式转型,企业年金制度的受益形式也正在从待遇确定型向缴费确定型转型。我国在建立企业年金制度时,应重点考虑以下几个方面:(1)应允许缴费确定型模式和待遇确定型模式的共存和竞争,鼓励实行各种混合型模式计划,增强制度的适应性;(2)应对企业年金给予有条件免税,在制定企业年金税制时应深入考虑缴费环节、投资环节和领取环节;(3)政府应用法律手段对企业年金进行宏观调控和规范,最大限度控制企业年金制度的运行风险;(4)企业年金应坚持以信托型为基本模式,吸取公司型的优点,包容基金型和契约型,走结合型创新的道路。  相似文献   
199.
温度畸变发生器研制   总被引:2,自引:2,他引:2  
介绍了航空发动机温度畸变试验装置的工作原理、设计技术要求、主要设备以及用涡喷和涡扇发动机调试和对比试验的结果。调试结果证明:该装置具有高的工作可靠性、可控性和稳定性,高温区平均温升值可达10-400K,绝对温升率可达300-5500K/s,可用于空气流量为30-150kg/s各类燃气涡轮发动机的温度畸变试验。  相似文献   
200.
船舶齿轮箱振动测试分析及优化研究   总被引:1,自引:0,他引:1       下载免费PDF全文
高珍  侯天柱  刘渊  常震罗  王英泽  丁毅  卢永文 《推进技术》2020,41(11):2587-2595
齿轮箱是船舶动力传动系统的主要振源之一,为了研究船舶齿轮箱振动性能及优化措施,进而实现船舶的低噪声化,以本单位自主研发的船用齿轮箱为例,通过台架试验和振动频谱分析结合的方法分析齿轮箱振动的主要影响因素,对振动性能关键影响因素进行优化改进。本文结合振动频谱分析结果对齿轮箱从齿轮修形设计和液压供油系统改进两个方面进行了优化,并对采取优化措施后的齿轮箱进行振动试验验证和振动频谱分析。结果表明:齿轮修形和液压供油系统改进两项优化措施可以切实有效的改善齿轮箱的振动性能。在文中的齿轮箱案例中,齿轮修形后齿轮啮合频率处振动峰值下降40.2%,总振级下降1.85dB,进一步采取液压供油系统改进措施后,齿轮箱总振级下降9.99dB。齿轮修形和液压供油系统改进对船用齿轮箱振动性能提升具有工程应用价值。  相似文献   
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