对交流电源装置做试验时的节能方法

本文介绍了一种对交流电源装置作试验的方法，该方法所采用的电路主要由两变流器组成，采用该方法做试验所消耗的电能经常规的方法要少得多而且对负载的适应能力也比较强，本文中，我们采用了一个简单的控制方法及系统设计，通过对一交流调速电机驱动器的原理实验，验证了该方法的有效性。     

生物驻极体材料对细胞生长的影响

研究天然生物高分子（如胶原）对组织损伤修复的影响．从猪皮中提取的Ｉ型胶原通过ＴＳＤＣ技术极化，并测试其驻极化前后的ＴＳＤＣ变化．将极化的材料用于细胞培养．得到了细胞生长曲线．实验证实，极化后的材料能加速细胞的生长．有可能用作生物医用材料．     

减阻聚合物薄膜的研制

表面修形技术,可以减少飞机阻力而不改变飞机结构,应用方便,维护简单,颇有吸引力。国外70年代开始进行该技术的研究,大多数研究者利用Riblets(它是一些具有顺流向开槽的平面,而沟槽面的形状通常为三角形,沟槽深为几个微米)来减小紊流附面层阻力[1].美国3M公司制造的自粘接Riblets     

关于励磁机的振动问题

励磁机振动是汽轮发电机组运行中较为普遍的一个问题。分析了导致励磁机振动的几个主要因素:结构共振、发电机振功传递、转子不平衡。还对其他若干因素的影响做了一些分析。     

电站通风机和电动机的现场平衡

介绍了电站通风机和电动机的现场平衡方法,并结合实例做了说明.     

Pediatric hepatic trauma: does clinical course support intensive care unit stay?

PURPOSE: The objective of this study is to determine if grade of liver injury predicts outcome after blunt hepatic trauma in children and to initiate analysis of current management practices to optimize resource utilization without compromising patient care. METHODS: A retrospective review of 36 children who had blunt hepatic trauma treated at a pediatric trauma center from 1989 to present was performed. Hepatic injuries graded (AAST Organ Injury Scaling) ranged from grade I to IV. Injury Severity Score (ISS), Glasgow Coma Score (GCS), transfusion requirements, liver transaminase levels, associated injuries, intensive care unit (ICU) length of stay, and survival were analyzed. RESULTS: Mean (+/-SEM) age was 6.6+/-0.8 years, mean grade of hepatic injury was 2.4+/-0.2, mean ISS was 17+/-2.6, mean GCS was 13+/-1, and mean transfusion was 15.4 mL/kg of packed red blood cells (PRBC). There were three deaths with a mean ISS of 59+/-9 and a mean GCS of 3+/-0. Death was not associated with a high-grade liver injury, survivors versus nonsurvivors, 2.3+/-0.2 versus 2.7+/-0.3, but was associated with ISS, 13+/-1.4 versus 59+/-9 (P = .005) and GCS, 14+/-1 versus 3+/-0 (P = .005). Only one patient (grade III, ISS = 43) underwent surgery. There were no differences in mean ISS or GCS between grades I to IV patients. The hepatic injury grades of patients requiring transfusion versus no transfusion were significantly different, 3.4+/-0.2 versus 2.2+/-0.2 (P = 0.04). Abused patients had high-grade hepatic injuries and significant laboratory and clinical findings. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were significantly higher in grade III and IV injuries than in grades I and II, 1,157+/-320 versus 333+/-61 (P= .02) and 1,176+/-299 versus 516+/-86 (P= .04), respectively. No children with grade I or II injury had a transfusion requirement or surgical intervention. There were no liver-related complications. CONCLUSIONS: Mortality and morbidity rates in pediatric liver injuries, grades I to IV, correlate with associated injuries not the degree of hepatic damage. ALT, AST, and transfusion requirements are significantly related to degree of liver injury. Low-grade and isolated high-grade liver injuries seldom require transfusion. Blunt liver trauma rarely requires surgical intervention. In retrospect, the need for expensive ICU observation for low-grade and isolated high-grade hepatic injuries is questionably warranted.     

CABG after patch angioplasty of the left main coronary: artery report of a case

A 57-year-old man was admitted to our hospital because of restenosis of the left main coronary trunk (LMT) after patch angioplasty for the LMT lesion. PTCA was repeated four times during three years after patch angioplasty, but recent coronary angiogram still demonstrated 75% restenosis of the LMT lesion. Double-CABG was performed to LAD and LCX using the left internal thoracic artery and saphenous vein graft. Postoperative coronary angiogram revealed an excellent result. A careful consideration must be given to the indication of the patch angioplasty of the LMT lesion.     

功能化的酸性离子液体

围绕着功能化酸性离子液体这一主题,对新型Lewis,Bronsted酸性离子液体、离子液体的酸性测定以及酸性离子液体在异丁烷/丁烯烷基化反应中的应用进行了介绍和评述;提出了由新型酸性离子液体的合成、其酸性的表征及其催化性能的评价3方面有机地构成了研发酸性离子液体参与的工艺技术的良性过程;明确了“功能化”的涵义;展望了酸性离子液体巨大的工业应用前景。     

Heat flow model for surface melting and solidification of an alloy

The heat flow model previously developed for a pure metal is extended to the solidification of an alloy over a range of temperatures. The eq11Ations are then applied to rapid surface melting and solidification of an alloy substrate. The substrate is subjected to a pulse of stationary high intensity heat flux over a circular region on its bounding surface. The finite difference form of the heat transfer eq11Ation is written in terM_s of dimensionless nodal temperature and enthalpy in an oblate spheroidal coordinate system. A numerical solution technique is developed for an alloy which precipitates a eutectic at the end of solidification. Generalized solutions are presented for an Al-4.5 wt pct Cu alloy subjected to a uniform heat flux distribution over the circular region. Dimensionless temperature distributions, size and location of the “mushy” zone, and average cooling rate during solidification are calculated as a function of the product of absorbed heat flux,q, the radius of the circular region,a, and time. General trends established show that for a given product ofqa all isotherM_s are located at the same dimensionless distance for identical Fourier numbers. The results show that loss of superheat and shallower temperature gradients during solidification result in significantly larger “mushy” zone sizes than during melting. Furthermore, for a given set of process parameters, the average cooling rate increases with distance solidified from the bottom to the top of the melt pool.