机械加工切削用量选择的线图法

常规切削用量的选择方法是通过平时加工的经验积累,或通过查工艺手册的查表法来获得。本文通过对经验切削用量的整理、作图,用查图法来获得切削用量,改进了查表法比较麻烦,且查得的参数点比较少的缺点,为零件在进行机械加工时方便的、大范围获得切削用量提供了一种有用的、切实可行的方法     

解Vacco动力学方程的常数变易法

给出解Vacco动力学方程的常数变易法.第一步,建立辅助方程;第二步,用通常的积分法解辅助方程;第三步,变易常数;最后,考虑非完整约束对初始条件的限制而得到Vacco动力学方程的解.这种方法揭示了非完整系统和完整系统的解之间的内在联系.     

热镀锌带钢抑制层的影响因素及控制要点

依据现有国内外热镀锌带钢理论研究和最新的实践研究成果,立足于冷轧热镀锌带钢工业化生产的实际情况,从带钢在退火炉中的运行速度、带钢入锌锅温度、锌液温度、退火炉露点、锌液Al含量五个方面阐述工业生产中热镀锌带钢抑制层的影响因素,梳理了抑制层的生长规律和控制要点,拟为热镀锌带钢的工业生产提供指导。     

汽车离合器基本参数的优化设计

汽车离合器的基本参教主要有离合器的后备系数β、摩擦面单位面积上的压力p0、摩擦片外径D和内径d等,这些参教的变化直接影响离合器的结构尺寸和工作性能。本采用优化设计方法来确定最佳的离合器基本参教,实例计算表明了该方法的实用性。     

Effects of continuous casting mould fluxes on reducing longitudinal and star cracks on a slab surface

1.IntroductionAstothecurrenttechnologyofcontinuouscastingofsteel,itisanemergencyformouldfluxestoharmonizetheconflictsbetweenheattransferandlubricationforslabcasting.Whenstructuralsteelwhosemassfractionofcarbonwcis0.09%to0.15%andhighstrengthlowalloysteel(HSLA)whosewcis0.14%to0.25%arecontinuouslycast,itisnecessarytocontroltheheatfluxfromtheslabshelltothecoppermouldnottoexceed1.7?06W/m2becauseofthebigandcoarseausteniticcrystalsintheinitialsolidifiedslabshell[1].Otherwise,longitudinalcrackstendt…     

Using Stated-Preference Questions to Investigate Variations in Willingness to Pay for Preserving Marble Monuments: Classic Heterogeneity, Random Parameters, and Mixture Models

This paper investigates heterogeneity in the preferences/WTP (willingness to pay) to preserve marble monuments in Washington, D.C. This is done in the context of three different discrete-choice random-utility models. The main focus is to estimate a mixture model of choices over preservation programs. This model captures the best features of random-parameters models and models that assume preference parameters are deterministic functions of observable characteristics of the individual. The mixture model, and it alone, predicts that increased preservation is a bad for a significant proportion of young, non-Caucasians. That some proportion of the population might consider preservation a bad is a contingency that should be planned for in efforts to value cultural resources. Data and computer code are available athttp://www.colorado.edu/economics/morey/dataset.html.     

中国国家女子手球队运动员赛前训练的生化特点及机能评定

为了解女子手球运动员赛前训练的生化特点和身体机能的变化规律.测定了19名参加2006年亚洲锦标赛赛前备战的国家女手运动员某些生化指标的变化.结果表明:1)赛前备战期国家女手运动员Rbc、Hb、Hct测定值变化幅度不大,在赛前2周达到了整个备战期的较高水平;2)赛前训练期,国家女手运动员白细胞总数在临床正常参考值范围;3)赛前训练期国家女手运动员血清CK、UREA变化幅度不大,血清CK的离散度较大;4)在赛前2周,国家女手运动员血清睾酮达到最高,血清皮质醇达到最低.结论:赛前运动员的血液携氧能力、营养状况、内分泌机能状态在赛前2周达到了较好状态;血清CK表现出较强的个体差异性.     

对国家男排队员跳发球技术的运动学比较研究

跳发球是近年来国内外男排比赛中主要的发球得分手段。本文通过对5名,中国男排队员的跳发球技术及2号位扣球技术、正面上手发球技术的影片解析,获取了跳发球技术的特征;揭示了跳发球与2号位扣球及正面上手发球在技术上的不同点,从而为跳发球训练提供一些理论依据和运动学参数。     

激光相变硬化层预测与控制简易模型

根据激光扫描时工件内温度场及硬化层的分布特征，提出了简便实用的硬化层预测计算公式。并在此基础上，提出了以硬化层分布均匀性最佳为目标的激光参数优化模型。     

Hierarchically structured porous materials: synthesis strategies and applications in energy storage

To address the growing energy demands of sustainable development, it is crucial to develop new materials that can improve the efficiency of energy storage systems. Hierarchically structured porous materials have shown their great potential for energy storage applications owing to their large accessible space, high surface area, low density, excellent accommodation capability with volume and thermal variation, variable chemical compositions and well controlled and interconnected hierarchical porosity at different length scales. Porous hierarchy benefits electron and ion transport, and mass diffusion and exchange. The electrochemical behavior of hierarchically structured porous materials varies with different pore parameters. Understanding their relationship can lead to the defined and accurate design of highly efficient hierarchically structured porous materials to enhance further their energy storage performance. In this review, we take the characteristic parameters of the hierarchical pores as the survey object to summarize the recent progress on hierarchically structured porous materials for energy storage. This is the first of this kind exclusively to survey the performance of hierarchically structured porous materials from different porous characteristics. For those who are not familiar with hierarchically structured porous materials, a series of very significant synthesis strategies of hierarchically structured porous materials are firstly and briefly reviewed. This will be beneficial for those who want to quickly obtain useful reference information about the synthesis strategies of new hierarchically structured porous materials to improve their performance in energy storage. The effect of different organizational, structural and geometric parameters of porous hierarchy on their electrochemical behavior is then deeply discussed. We outline the existing problems and development challenges of hierarchically structured porous materials that need to be addressed in renewable energy applications. We hope that this review can stimulate strong intuition into the design and application of new hierarchically structured porous materials in energy storage and other fields.