分布式立体温度监测系统在湿法电解工艺的应用

分布式立体温度监测系统采用分布式光纤感温探测,可以精确地判断湿法电解工艺中电解槽内电解配液的流动和循环情况,辅助判断电解过程,发现和定位电解槽的异常状况,有效的确保电解工艺长期稳定的运行,减少工艺故障,降低能耗损失,提升生产效能。     

基于交错断续空间矢量调制的并联PWM变流器控制策略

并联PWM变流器可以显著增大变流器的容量并提高交流侧的电能质量,但是变流器的直接并联容易在其内部产生环流,从而导致变流器损耗增加甚至开关器件损坏.本文以三相PWM整流器并联系统为例给出了环流的数学模型,该环流是一个存在于零轴的带直流偏移量的环流.针对环流问题,本文通过建立并联系统的小信号模型分析确定了零序电流环的设计,并采用了交错断续空间矢量调制方法来消除和抑制其对整个系统的影响.通过该方法,环流可以用dq轴分量表示,并通过功率因数校正(PFC)电路的电流环加以抑制.最后的仿真和实验验证了本文控制策略的有效性.     

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依据低密度和气泡变形堵塞理论，分析了微泡沫钻井液的防漏堵漏原理。采用砂石充填的模拟漏层实验方法，研究了无粘土相微泡沫钻井液防漏堵漏作用效果，结果表明，微泡沫钻井液对80～120目砂石构成的孔隙通道具有最好的堵漏效果，对40～80目砂石构成的孔隙通道具有良好堵漏效果，对10～40目砂石构成的孔隙通道具有一定的堵漏效果，而且，随着压力增加，微泡沫钻井液仍具有堵漏承压能力。     

300MW机组循环水泵增容改造的分析

通过对３００ＭＷ机组所配置的循环水泵出现问题的分析，提出了并实施了更换高效叶轮的计划。将新水轮由原来４片改为５片，叶轮也改了型，另外还分析了改造后的效果。     

Grease Lubrication of a Multiple-Branch Mechanical System

Abstract

Greasing is the preferred lubrication method in many mechanical devices. To simplify the design, some systems use multiple branches so that the grease must go through channels or different restrictions to reach target spots. Conceptually, flow restriction can be included in the design to achieve optimal grease distribution, but the detailed design can be complicated. For example, appropriate dimensions of various machine elements and their manufacturing tolerances must be considered along with the property of the grease, its feeding device, and its seal design. Currently, grease-feeding design relies heavily on experimental tests. A system-level modeling and analysis is desirable to understand the sensitivity of design parameters to the overall lubrication performance. In the study of grease lubrication of a universal joint, we have developed a semi-empirical model to address this challenge. The model is found useful to provide design guidance. The methodology can be extended and applied to more complicated cases. Laboratory tests on grease flow rates were conducted for a number of design alternates. Based on these data, the functional relationship of an equivalent discharge coefficient and the system parameters can be determined. Charts generated by the analytical model provide designers with a convenient tool for making design decisions.     

降低精密数控车床进给轴热误差对切削精度影响的方法

精密数控车床批量加工零件的精度稳定性是衡量机床性能的重要指标,其中加工过程中的进给轴受热伸长是影响加工精度的重要因素之一。对数控车床进给轴热变形方向及伸长量进行研究,对比丝杠预拉伸及数控系统热误差补偿功能,指出这两种降低进给轴热误差方法局限性,提出一种使用中空油冷循环系统降低进给轴热误差的方法。该中空油冷循环系统,一方面通过中空丝杠内循环的冷却油带走丝杠螺母的发热量,另一方面通过轴承室内循环冷却油带走轴承的发热量。进行了系统结构设计与实验验证,结果表明该系统可以使进给系统在加工时保持温度稳定,降低热误差,进而提升批量加工的精度稳定性。     

新型咪唑啉酰胺缓蚀剂的合成及性能评价

针对高酸原油加工中分馏塔顶循环回流系统腐蚀加剧的现状,以油酸、二乙烯三胺和乙酸酐为原料合成了一种咪唑啉酰胺化合物缓蚀剂——油酸二乙烯三胺咪唑啉酰胺(EYP),并采用1HNMR和FTIR对其结构进行了表征,采用热重分析法对其热稳定性进行了考察。利用失重法考察了该缓蚀剂在模拟顶循油体系中的缓蚀性能,并与市售缓蚀剂进行性能对比,采用SEM对碳钢表面的腐蚀形貌进行分析。结果表明,EYP具有较好的热稳定性,在模拟顶循油体系中对A3碳钢具有优良的缓蚀性能,是一种稳定性好且高效的缓蚀剂。     

循环酸洗法在压缩机级间冷却器清洗中的应用及推广

由于氮压机级间冷却器严重结垢,氮压机压缩气体的能力大大减小而且喘振现象频繁发生。通过对氮压机水路进行加装反冲洗阀的改造,并采用改进后的循环酸洗法对氮压机进行酸洗,从根本上解决了氮压机级间冷却器严重结垢问题,取得了降本增效的效果。简介氮压机的运行状况,详细阐述改进后的循环酸洗方法及具体实施过程,分析氮压机级间冷却器清洗后的效果,最后介绍循环酸洗法的推广应用。     

浅低温不停跳心内直视手术体外循环436例分析

目的分析浅低温不停跳下心内直视手术体外循环病例选择及临床意义。方法对1999年3月-2009年5月期间436例简单先心浅低温不停跳下心内直视手术体外循环灌注情况进行回顾性研究。年龄≤12岁小儿组263例,年龄>12岁成人组173例,对两组患者体外循环中流量、压力、温度等情况进行比较。结果与成人比较,小儿灌注流量明显高于成人(P<0.01),平均动脉压明显低于成人(P<0.01);术中平均温度和转机时间两组无统计学差异(P>0.05)。436例患者术后均痊愈出院。结论体外循环下心脏不停跳心内直视手术,对于简单先心病患者是安全可靠的。     

In situ, near real-time acquisition of particle motion in rotating pan coating equipment using imaging techniques

The uniformity of coating applied to large particles and tablets in rotating-drum coating devices is of significant interest to the Pharmaceutical Industry, especially when the coating contains active material or provides a sustained release barrier for drug transport in a functional coat. The purpose of this research was to quantify parameters that characterize the movement of tablets through the region where they receive maximum coating. The three parameters of greatest interest are (1) circulation time (τ_circ), (2) surface exposure time (τ_surf) and (3) surface area of the tablet projected toward the spray source (nozzle) during each pass through the spray zone (A_tab). In order to measure these parameters, a digital imaging system was developed and implemented to analyze images of the surface of the tumbling tablet bed in near real-time.The drum rotation rate was varied between 6 and 12 rpm, at two different drum fills of 1/8 and 1/4. Three tablet sizes, 6.3, 7.9 and 10.4 mm, were used. The circulation time was found to vary from 2.9 to 15.5 s and the surface time from 0.06 to 0.2 s. Decreasing trends for circulation and surface times were observed with increasing drum speeds, drum loadings, and tablet size. A_tab and surface velocities were also estimated for the movement of tablets through the spray zone in the rotating drum. The axial dispersion coefficient was estimated from random walk theory. It was found to lie in the range of 0.2×10^-3- for the conditions studied and was found to increase with increasing drum speed.