热声系统的工程优化设计

介绍了热声系统无因次化的工程优化设计数学模型,描述了热声系统的优化算法.对声驱动的热声制冷机和热声发动机两种典型的热声系统的板叠,进行了优化设计计算,得到了两系统中热声板叠的性能和效率曲线,并对影响热声系统性能或效率的因素进行了分析与讨论,优化确定了板叠的结构参数,为热声系统的工程优化设计和性能预测提供了一种有效的方法.     

Filling Rules of Bevel Gears in the Closed-die Cold Forging

1. Introduction Closed-died cold forging technology is a new precision forming method. It was developed from the 1980's, by which large deformation and complex moulding surfaces can be obtained in one step. So it suits to the production of the complex parts[1,2]. The principle of closed-die cold forging is different from forging. For closed-die forging, it is a combination of radial extrusion and forging. Its principle is shown in Fig.1. The tool consists of dies and punches. The forming pro…     

Mathematical Model for Tempering Time Effect on Quenched Steel Based on Hollomon Parameter

1. IntroductionTempering is an absolutely necessary process in whichthe modification of the microstructure, the improvementof mechanical properties and the removal of the stressin quenched steel have been achieved. With the develop-ment of technology & equipment[1], and the advancementof automation for heat treatment industry, the temper-ing time effect, i.e. the variation of the strength & hard-ness of quenched steel with the tempering time duringtempering, is a necessarily considered factor[…     

Research on Retained Austenite for Advanced Aluminum-containing Hot-rolled TRIP Steel

1. IntroductionTransformation induced plasticity (TRIP) steels havebeen well known for the well balanced comprehen-sive mechanical properties with high strength and highplasticity[1~13] and can be used to press form thevehicle's parts to increase the safety and save the oilby increasing the strength and reducing the weight forautomobile[14~17]. Silicon is one of the common andcheap elements to be added into the steel to increase re-tained austenite stability[18,19]. However, silicon tendsfor…     

Optical Properties of Nb+ Ions Implanted Sapphire before and after Annealing

1. IntroductionSapphire is a hexagonal-close-packed (hcp) mi-crostructure where Al ions occupy two thirds of the oc-tahedral interstitial positions of oxygen ions' sub-lattice.The pauling ionicity of Al2O3 is 0.63[1]. It is an excel-lent oxide material due to its high melting temperature,wide transparency, relatively high chemical stability andhardness. Doped sapphire can be used for an importantpart of laser.Ion implantation into solid can make its compositionalter, also produce radiation d…     

AML-2车载激光雷达测量臭氧的大气后向散射系数项修正方法研究

对于准同时发射两个波长激光的差分激光雷达,在测量时间内,大气波动对两个波长的激光回波信号的影响可能是不相同的.已有的大气修正方法是基于两个波长激光回波信号受到相同大气波动的基础之上,不适用于这种准同时的工作方式.提出了一种新的大气后向散射系数项修正方法,即利用Klett积分法,分别算出差分吸收激光雷达中两个波长激光的大气后向散射系数,得出大气后向散射系数修正项.这种方法应用于AML-2车载激光雷达测量臭氧的数据处理中,比对实验和大量的外场测量结果表明,这种修正方法是可行的、合理的.     

同赴音响盛宴——三诺音响2008年度第一届摩机大赛起因及范例

一个新的音箱Hi-Fi时代已经到来!传统的CD播放机在音质上的优势正日渐消失,而在节目源以及使用的便利程度上更是远远落后于PC,对于谙熟电脑应用的新人类来说,PC以及新的以PC为中心应用背景的相关数码设备正逐渐发展成最重要的音乐播放设备。我们愿意称这群新兴;隹专业音响用户为“PC-HiFi”。     

诺基亚西门子获突尼斯GSM—R合同

诺基亚西门子日前宣布,获突尼斯国家铁路公司（SNCFT）GSM—R合同。根据合同．诺基亚西门子将提供端到端GSM—R解决方案,包括基站、基站调度、调度设备以及手持设备等。     

茂金属耐热聚乙烯管材料的结构与性能

对3种茂金属耐热聚乙烯（PE-RT）管材料（ M 1,M 2和M 3）的基本物性、热性能、相对分子质量及其分布、力学性能、流变性能等进行分析表征,考察了3种PE-RT管材料的性能差异。结果表明: 3种PE-RT管材料均属于中密度聚乙烯产品,熔体流动速率相近;3种PE-RT管材料中,国产料M 1,M 2的分子质量分布较宽,熔点较低,结晶度小,韧性较好;进口料M 3的熔体拉伸强度较大,可拉伸性最佳,弯曲弹性模量高,具有良好的刚性。     

圆柱弯曲型超声波电动机定子优化设计

圆柱弯曲型超声波电动机在工作时其定子要具有合适的工作模态.为满足该工作模态,早期设计中需对定子结构设计方案进行多次修改和试算,该方法耗时又不理想.在参数化设计语言APDL的环境下编制了定子结构优化设计程序.计算结果表明:该程序能准确地识别出定子所需工作模态,优化后的定子结构满足预期的设计要求,且计算精度和设计效率得到提高.