新桥水库工程泥沙设计中的几个问题

实践经验表明,水库工程泥沙设计的关键在于合理确定泄洪排沙洞的进口高程、洞径及其平面位置。本文对陕北红柳河流域新桥水库泄洪排沙洞设计中的几个关键性问题进行了探讨,并给出了适合北方多沙河流上中小型水库泄洪排沙洞泄流曲线的计算方法。     

Mechanical properties,corrosion resistance,and rubber pad forming of cold differential speed-rolled pure titanium for bipolar plates of proton-exchange membrane fuel cells

Due to problems such as pores on surface-treated coatings, the corrosion resistance of pure titanium bipolar plates for proton-exchange membrane fuel cells can be further improved by increasing the corrosion resistance of pure titanium by using differential speed-rolling (DSR); however, these materials have not yet reached the standard requirements of bipolar plates (corrosion current density i_corr＜10³ nA·cm^?2). In this work, the corrosion resistance of pure titanium was improved by optimizing the DSR process while the strength was maintained. The best corrosion resistance of the DSR pure titanium was achieved when the roller speed ratio was 2, while i_corr was 429 nA·cm^?2 in a solution of 0.5 M H₂SO₄ and 2 mg/L HF at room temperature. The formability of the DSR pure titanium for bipolar plates was verified. The optimal holding pressure range was 6.8–7.0 kN.     

离心铸造太阳电池硅片液态成形机制的研究

为了将离心铸造技术成功地移植到低成本超薄多晶太阳电池硅片的成形工艺上，提出了ＥＬＣＣ技术的硅片液态成形方法，即将铸模型腔预热至硅熔点以上温度，过热的硅液被浇注到型腔后，在离心力的作用下始终保持液态充型。这种成形机制易于实现厚度小于１ｍｍ的硅片的完整成形，而且对模具转速、硅液过热度等要求较低。采用该方法，硅片的成形与结晶不会同时发生，可以在硅片液态成形后，采用定向凝固的方法获得粗大的定向柱晶组织，提高硅片的光伏性能。采用理论分析、计算机模拟与工艺实验相结合的方法，对ＥＬＣＣ技术硅片液态成形机制进行了研究，为进一步对硅片凝固过程组织控制的研究奠定基础。     

Two-stage forming approach for manufacturing ferritic stainless steel bipolar plates in PEM fuel cell: Experiments and numerical simulations

Multi-stage micro-channel forming by stamping, as a method for cost effective and efficient for mass production, was performed for ultra-thin ferritic stainless steel sheets with thicknesses of 0.1 and 0.075 mm, as a good substitute for traditional graphite bipolar plates of proton exchange membrane fuel cell. Attention was directed to enhance the final forming depth and minimize localized thinning, extremely important aspects of the micro-channel on bipolar plate, by the proposed forming process. A forming depth at the first forming stage was chosen as a process variable, and its effect on the formability of the micro-channel at the second forming stage was experimentally investigated. Finite element simulations for the two-stage forming process were conducted to optimize the punch radius and forming depth at the first stage for improving the formability. The comparative study between the simulations and the experimental results could validate improvements in the formability by the proposed approach. In particular, this study could support the existence of an optimum forming depth at the first forming stage. Based on the simulation results, a mathematical model was established to identify the dominant factor needed for formability improvement and to propose a methodology for the process optimization of the multi-stage forming.     

空调底板的结构优化与冲压成形仿真

以某空调底板为研究对象,对其进行了三维建模、结构优化及冲压成形仿真。在减薄空调底板厚度的情况下,采用ANSYS Workbench软件对底板进行多目标优化,使底板的刚强度同时满足要求;并对优化后的底板采用Dynaform进行冲压成形仿真,通过工艺参数的调整,使结构优化后的底板冲压取得较好的成形效果。结果表明：采用基于有限元法的数值仿真技术,大大缩短了产品开发周期,并降低了开发成本。     

熨烫工艺影响不同面料服装造型的量化研究

应用传统的推归拨熨烫技术,在相应的温度、湿度、压力、时间、冷却方式等条件下,根据人体起伏变化及省缝的服用要求设计实验。对常用的天然纤维、合成纤维、混纺纤维等11种不同面料,在人体相应的尺寸设计量下进行熨烫,并对其变化结果进行分析,得出了天然纤维面料因其自身良好的特性,在测试中只要控制好基本参数,拨开和归进效果良好,同时面料的长短变化对推归拨的空间量也有一定的影响,也说明了天然纤维面料通过归拨后在满足人体立体服用需要时有很好的表现,并通过实例得到了证明。合成纤维面料弹性好,吸湿性差,纱线间摩擦因数小,推归拨保形时间短暂,还须加大熨烫时的工艺参数以达到良好的效果。混纺纤维具有2种纤维的长处,保形良好。当然在熨烫时归拨的量化大小还要紧密地和人体骨骼、肌肉相联系,做到有的放矢。     

半轴套管产品集成开发研究

 为了节省材料、降低制造成本和提高生产率,在分析产品负荷特征,装配关系及原设计和工艺的弊端后,对汽车半轴套管进行了产品集成开发研究.从分体式设计开始就考虑先进的复合成形工艺与用户的要求等因素.在分体式设计的基础上采用创新的正挤与横轧工艺和摆动辗压工艺成形半轴套管后,收到了节材、节能,提高生产率与降低制造成本等综合经济效益.     

LEFP 成型及侵彻过程的数值模拟

为反映线性爆炸成型侵彻体（liner explosive formation penetration,LEFP）成型及侵彻过程中各参数的变化规律,合理设计LEFP装药结构参数,利用LS-DYNA 3D有限元动力分析软件,采用任意拉格朗日-欧拉（ALE）算法,建立包括炸药、药型罩、壳体、空气、靶板在内的三维数值模型,在分析线性爆炸成型侵彻体成型过程的基础上,通过数值模拟和实验进一步分析了LEFP对45#有限钢靶板的侵彻效应。结果表明,该模拟方法正确,能为LEFP的设计提供参考。     

成型压力对铜基粉末冶金摩擦材料性能的影响

研究成型压力对铜基摩擦材料显微组织和性能的影响。结果表明,铜基摩擦材料的密度随成型压力的增加基本保持不变;随着成型压力的增加,孔隙率明显降低,致密度提高。当成型压力从60t增加到100t时,铜基摩擦材料的硬度明显提高,当成型压力继续增加时,硬度出现下降趋势;铜基摩擦材料的摩擦系数随着成型压力的增加呈先降低后增加的趋势。在成型压力为100t时,铜基粉末冶金摩擦材料的综合性能最佳。     

智能反射面实现空间调制的安全系统性能分析

为了解决安全空间调制系统中合法信道增益差的问题,提出了一种用智能反射面(Intelligent Reflective Surface,IRS)实现空间调制的物理层安全传输方案。IRS接收到发射端发射的幅相调制信号后,通过选择不同的IRS反射元件序号对空域部分信息进行映射,再将信号反射到接收端,以增大窃听端获取完整信息的难度。此外,在发射端采用波束赋形和天线分集技术,提高了系统有效性和可靠性。对系统的保密速率和误比特率进行的理论分析和仿真实验结果表明,所提方案不仅可以提高系统保密速率,还可以降低合法接收端的误比特率。