Non-Fourier Heat Conduction Effects During High-Energy Beam Metalworking

Non-Fourier heat conduction induced by ultrafast heating of metals with a high-energy density beam was analyzed. The non-Fourier effects during high heat flux heating were illustrated by comparing the transient temperature response to different heat flux and material relaxation times. Based on the hyperbolic heat conduction equation for the non-Fourier heat conduction law, the equation was solved using a hybridmethod co mbining an analytical solution and numerical inversion of the Laplace transforms for a semiinfinite body with the heat flux boundary. Analysis of the temperature response and distribution led to a criterion for the applicability of the non-Fourier heat conduction law. The results show that at a relatively large heat flux, such as greater than 108 W/cm2, the heat-affected zone in the metal material experiences a strong thermal shock as the non-Fourier effects cause a large step increase in the surface temperature. The results provide a method for analyzing transient heat conduction problems using a high-energy density beam, such as electron beam deep penetration welding.     

句重音与句末语气词的时长和能量

实验分析了重音位于句首、句中和句末三种情况下句末语气词时长和能量的变化情况。分析结果表明,句重音能够对句末语气词的时长和能量产生比较大的影响。重音位于句首和句中时语气词时长短、能量小;重音位于句末时,语气词时长长、能量大。     

无土栽培盆景的养护管理技术

无土栽培盆景是近年盆景种植的一种新方式。但是,在其种植过程中常出现植株生长缓慢、叶片发黄脱落、开花多结果少、甚至只开花不结果等现象。根据多年的养护管理经验,现就从消毒、营养液、光照、空气湿度及病虫害防治等几方面简单总结一下无土栽培盆景的养护管理技术。     

基于有限元法和边界元法的轻量化车身声学分析

应用计算机辅助工程分析技术对一更换材料和板厚的轻量化七座客车进行声学分析.在计算声压响应时,应用有限元法进行了车身结构的频率响应分析,将计算所得的结构壁板速度响应作为内部声腔的边界条件,采用边界元法计算乘员室内部的声响应.由于整车结构优化的复杂性和汽车轻量化的要求,只对高出原结构声压响应的声压峰值进行了壁板贡献度分析,确定了贡献度最大的板,使后续的结构优化更有针对性.     

Virtual Prototype Simulation and Reliability Analysis for Drive System of Armored Chassis

Drive system is the key device of armored chassis. Its working state and reliability influence the maneuver performance of armored chassis directly. In order to simulate the failure process and evaluate the service reliability of drive system in training or battle missions,a new kind of dynamic simulation model and driving simulation platform of the complete drive system were established based on virtual prototype and finite element technology in this paper. Using the platform, the kinematics and dynamic characteristics of drive system were studied and analyzed in detail,the dynamic load spectrum of key components was obtained,the service life was predicted, and the service reliability evaluation results were provided. A simulation example of transmission gear was shown to illustrate the simulation and evaluation process. The result proves that the simulation method not only can be used to compute and evaluate the service reliability of complex mechanical mechanism, but also has high precision and reasonable computational cost. Therefore,simulation and reliability analysis based on virtual prototype of the armored chassis drive system will provide scientific reference for the formulation of armored chassis reasonable repair cycle.     

茶叶与杭州文化产业的发展——浅谈杭州“茶都”文化产业业的发展两维

明媚春光的俯照下,温柔美丽的西子湖畔,送来了濒湖茶山的缕缕清香。2005中国(杭州)西湖国际茶文化博览会在阵阵龙井茶香中隆重开幕。来自五湖四海的专家、学者云集杭州,共享这美妙的一刻。在本次茶文化博览会上,杭州被授予了"中国茶都"的称号。杭州这座城市,与茶有着千丝万缕、密不可分的联系。杭州产茶的文字记载,见诸于桐君所著的《桐君采药录》。书中曾述":武昌、庐江(今安徽境内)、晋陵(今江苏武进)好茗,而不及桐庐。"据考证,桐君系距今4000多年的黄帝时人,是我国医药史上卓有成效的中医药学家,他曾在杭州桐庐一带采药。可见,杭州起码已有4000多年的产茶史。在这漫长的岁月中,杭州检索到了像白居易、苏东坡那样的大文豪在西湖的山林石泉边雅聚品茗的身影,也听到了乾隆对西湖龙井茶的由衷赞叹,更寻觅到径山茶宴步出国门、东渡日本的脚印……这些历史的印痕弥漫开来,使这座城市的饮茶习俗浸润在浓浓的文化氛围之中,绵延至今,兴盛不衰。为了让所有读者都能感受到茶文化的浓厚,本刊特选了获得本次"倡导茶为国饮,打造杭为茶都"高级论坛论文一等奖的2篇作品刊登,以飨读者。     

雄番鸭与雌麻鸭人工授精的研究

本文报导雄番鸭与雌麻鸭人工授精的研究.实验证明: 以台鸭诱情, 用手指按摩雄鸭泄殖腔口,刺激其翻出阴茎,用搪瓷杯承接射出的精液,经稀释液稀释后,用特制的输精器,辅以食指定位法授精。这种授精方法简便准确,适于养鸭专业户的推广使用。番鸭精子在麻鸭输卵管中存活1～3天时,卵子受精能力较强,受精率为57～63％。从第四天开始下降到44％左右。实验表明,为维持较高的受精率,每三天输精一次较为合适。在雄鸭不足的情况下,亦可四天输精一次,受精率仍能维持在58％左右。通过人工授精,一只雄番鸭每日采精一次能够配种8～15只母麻鸭(可间隔3～4天授精一次)。而人工辅助配种,一只雄番鸭每日只能配一只雌麻鸭(一般间隔5日重行交配)。两者相比较,人工授精效果比人工辅助交配高5～9倍,不但节省配种的雄番鸭数目,而且缩短配种操作时间,有很高的经济效益。     

一种单头双螺杆的啮合特征

根据啮合理论推导了ＨＳＢ４００／２型单头双螺杆式油气混输泵的平面和空间共轭齿形型线方程及啮合线方程。给出了各段原始齿形型线和空间螺旋曲面方程。单头双螺杆泵与双头双螺杆泵密封腔的密封原理相同。两螺杆的齿形型线不同,但啮合线封闭,接触线连续,能够形成密封的工作基元     

Jabber／XMPP技术的研究与应用

分析了Jabber/XMPP(eXtensibleMessagingandPresenceProtocol)协议的体系结构,并对网络中不同的即时通信通用协议进行了比较。之后,阐述了XMPP的安全机制和工作过程。在此基础上,对基于XMPP的即时通信系统及其在企业协同系统中的应用进行了研究。     

基于相位分析与散射点关联的速度估计方法

宽带探测为目标高精度运动参数估计提供了可能。然而, 目标多散射特性以及姿态变化等因素限制了测速性能的进一步提升。为此, 提出一种基于相位分析与散射点关联相结合的有效方法。首先, 通过建立分段匀加速直线运动模型, 采用包络对齐方法与自适应Chirplet分解方法相结合的方式, 从回波的相位变化中提取出目标的运动信息。然后, 使用预测-观测的关联方法, 去除其中非平动因素的影响, 提高平动速度的估计精度。最后, 实测数据的实验结果证明了所提方法的有效性。