Experimental investigations into triplex hybrid process of GA-RDECDM during subtractive processing of MMC’s

The use of Al-6063 SiCp metal matrix composites (MMCs) in electronic packaging applications, heat sinks for printed circuit boards and for microwave housings necessitates certain degree of machining operations to meet the specifications of the product. The various conventional and non-conventional machining processes had been used to machine the MMCs. But all such processes have their limitations in providing the desired outcomes. Therefore, the present research endeavor, a new process variant of ECDM for the machining of Al-6063 SiCp MMCs. The developed grinding assisted rotary disk electrochemical discharge machining (GA-RDECDM) process integrates the concept of triplex hybridization. In GA-RDECDM, an abrasive coated rotary disk was used as a tool electrode. The abrasive coated disk provides micro gaps between the tool electrode and work material surface and thereby it results in thin and stable gas film formation. The breakdown of thin and stable gas films produce high frequency, low intensity discharges and consequently improves the machining performance. The additional abrasion action imparted by rotating disk ensures the continuation of ECDM process. The influence of various process parameters including applied voltage, pulse on time, electrolyte concentration and the disk rotation rate on width over cut (WOC) and depth were experimentally investigated. Multi criteria optimization using desirability approach predicts the parametric combination of applied voltage of 99V, pulse on time of 3 ms, electrolyte concentration of 17%wt./vol. and disk rotation rate of 30 rpm as the optimum setting for fabrication of slits on the MMCs. The underlying process mechanism is also investigated and presented with appropriate illustrations. The major contribution of the present research work is the development of a novel method for the fabrication of the slits on MMCs.     

燃气三联供耦合光伏系统运行策略优化

为提高燃气三联供耦合光伏系统的运行能效,以上海市某办公大厦分布式项目为例,在综合考虑项目设备特性、峰平谷电价和项目发电成本等因素的基础上,首先建立系统性能评估及经济性测算模型,然后对不同边界条件下三联供与国网直供能系统的经济性进行分析比较。最后结合大厦负荷现状,以系统综合运行费用为优化目标,确定冬、夏季典型日负荷工况下系统的运行策略。结果表明：电价高峰、平段时,三联供系统均具有良好的经济效益,电价低谷时当冬、夏季天然气价格分别高于3.69和3.99元/m³时直接用国网直供能运行费用更低。优化后系统运行策略方案与常规方案相比,每年可减少运行费用190.42万元,二氧化碳排放量236.06 t,经济及环保效益显著。     

Highly stable DNA triplexes formed with cationic phosphoramidate pyrimidine alpha-oligonucleotides

The ability of cationic phosphoramidate pyrimidine alpha-oligonucleotides (ONs) to form triplexes with DNA duplexes was investigated by UV melting experiments, circular dichroism spectroscopy and gel mobility shift experiments. Replacement of the phosphodiester linkages in alpha-ONs with positively charged phosphoramidate linkages results in more efficient triplex formation, the triplex stability increasing with the number of positive charges. At a neutral pH and in the absence of magnesium ions, it was found that a fully cationic phosphoramidate alpha-TFO (triplex-forming oligonucleotide) forms a highly stable triplex that melts at a higher temperature than the duplex target. No hysteresis between the annealing and melting curves was noticed; this indicates fast association. Moreover, the recognition of a DNA duplex with a cationic alpha-TFO through Hoogsteen base pairing is highly sequence-specific. To the best of our knowledge, this is the first report of stable triplexes in the pyrimidine motif formed by cationic alpha-oligonucleotides and duplex targets.     

电磁干扰导致发电机励磁系统误动的分析

随着发电机单机容量的增大,厂用电配电网络中电缆线路产生的电磁干扰问题愈来愈不容忽视。特别是高压大容量电动机的起动过程,暂态时间长、电流幅值大,如果控制电缆的敷设未按照相关标准进行,将会对机组励磁等某些敏感设备造成电磁兼容性故障,影响发电机的正常运行,进而破坏电力系统稳定。针对一台300MW汽轮发电机在机组电动给水泵起动时励磁系统跳闸的故障现象,从励磁系统灭磁逻辑、设备安装现场的电磁环境方面进行系统分析,认为误动跳闸是电磁干扰引起的。提出并采取将安装于控制室的自动电压调节器(AVR)柜迁移至发电机底部的励磁室、以消除给水泵动力电缆与励磁低压电缆间电感性耦合干扰的改造措施。两年多的运行实践验证了分析的正确性和改造措施可行性。     

三层系统中自定义标签的实现

报道了自定义标签在三层系统中的实现,找出Web应用系统中View层的表现模式的解决办法,建立一套针对业务领域的自定义标签库.在用户界层抽取复杂的各种业务表现模式,抽取出最小、可实现的表现元素,并归类整理后定义在标签库描述文件中.针对每个标签的解析文件,以便在运行过程中能够解析符合J2EE规范的自定义标签,最后通过Web应用的配置文件对自定义标签的引入及JSP程序对自定义标签的使用,解决用户界面显示要求灵活多变和操作控制复杂的问题,保证系统的稳定性.     

塑料共挤出吹塑重包装复合膜机组的研发及特点

针对三复合重包装膜应用日益广泛的现状，开发了塑料共挤出吹塑重包装复合膜机组。配备了精密的自动称量和配送供料系统，高产量挤出机，精密双螺旋平面叠加复合机头，闭环控制的自动风环，拥有自主专利的内冷系统，精巧的稳泡机构，旋转器、电晕处理器等。介绍了膜的性能要求和设备技术规范。     

低波动往复泵无冲击运动分析

对于三缸低波动往复泵，理论上应使三个活塞在排出行程（吸入行程）中的速度之和为一常数，采用凸轮机构能达到这一目的。满足这一要求的活塞运动曲线有多条，本文论述了一条无冲击运动曲线；给出了活塞的位移、速度、加速度曲线及解析表达式。活塞加速度曲线为连续曲线，可避免活塞对凸轮的冲击。     

用于2000型压裂车的三缸泵和五缸泵试验研究

供2000型压裂车选择的柱塞泵有三缸泵和五缸泵2种。为了验证压裂车和柱塞泵的性能，进行了台架试验、出厂试验和现场工业试验。经试验研究表明，五缸泵压裂车的参数覆盖范围较三缸泵压裂车有明显优势，五缸泵的泵效优于三缸泵。