Cusp flows due to an extended sink in two dimensions

The steady two-dimensioanl potential flow of a finite-depth fluid into an extended or distributed sink, in which the free surface dips to form a cusp above the centre of the sink, is examined. The extended sink is a region where the vertical outflow velocity V is constant and uniform. Numerical solutions for the free-surface profiles are obtained by use of a boundary-integral technique. Solutions are only found for the supercritical case where the Froude numbers are greater than one. In the limiting case where the extended sink width tends to zero, the problem reduces to that of a line sink beneath the free surface, and comparisons are made to existing results for this type of flow.     

Individual- and organizational-level consequences of organizational citizenship behaviors: A meta-analysis.

Although one of the main reasons for the interest in organizational citizenship behaviors (OCBs) is the potential consequences of these behaviors, no study has been reported that summarizes the research regarding the relationships between OCBs and their outcomes. Therefore, the purpose of this study is to provide a meta-analytic examination of the relationships between OCBs and a variety of individual- and organizational-level outcomes. Results, based on 168 independent samples (N = 51,235 individuals), indicated that OCBs are related to a number of individual-level outcomes, including managerial ratings of employee performance, reward allocation decisions, and a variety of withdrawal-related criteria (e.g., employee turnover intentions, actual turnover, and absenteeism). In addition, OCBs were found to be related (k = 38; N = 3,611 units) to a number of organizational-level outcomes (e.g., productivity, efficiency, reduced costs, customer satisfaction, and unit-level turnover). Of interest, somewhat stronger relationships were observed between OCBs and unit-level performance measures in longitudinal studies than in cross-sectional studies, providing some evidence that OCBs are causally related to these criteria. The implications of these findings for both researchers and practitioners are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

序贯法测定羟考酮皮下注射用于Stanford A型主动脉夹层撕裂患者术前镇痛的半数有效剂量

目的:采用序贯法测定羟考酮皮下注射用于Stanford A型主动脉夹层撕裂患者术前镇痛的半数有效剂量(ED50)。方法:Stanford A型主动脉夹层撕裂患者30例，美国麻醉医师协会(ASA)分级Ⅱ～Ⅲ级，拟于全身麻醉下行急诊手术。根据序贯法增减给药，麻醉前60 min时第一例患者皮下注射羟考酮5.0 mg，相邻剂量梯度为0.5 mg，若上一例患者镇痛效果满意，则下一例患者剂量减少0.5 mg；若上一例患者镇痛效果不满意，则下一例患者剂量增加0.5 mg。序贯给药后采用视觉模拟评分法(VAS)评估镇痛效果，VAS≤3分为镇痛有效。采用Dixon and Massey序贯分配试验法公式计算羟考酮皮下注射用于Stanford A型主动脉夹层撕裂患者术前镇痛中的ED50和95%可信区间。结果:镇痛效果满意组患者总体满意度高于镇痛效果不满意组(P<0.05)，而两组补救镇痛率差异无统计学意义(P>0.05)。皮下注射羟考酮用于Stanford A型主动脉夹层撕裂患者术前镇痛的ED50为2.9 mg，95%可信区间为2.3～3.4 mg。结论:采用序贯法测得的皮下注射羟考酮用于Stanford A型主动脉夹层撕裂患者术前镇痛的ED50为2.9 mg，且此法简便、高效、准确性高。     

厚煤层综放工作面停采撤架期间防灭火技术研究与应用

分析了厚煤层综放工作面回撤期间煤炭自燃的主要原因,提出了停采撤面前的保障措施以及撤除期间主要防治技术,认为快速撤离"三机"同时加强采空区灌浆堵漏是防治采空区煤炭自燃的关键。     

Total control-based unified allocation model for allowable basin water withdrawal and sewage discharge

In this paper,a new model with a total amount control target of allowable water withdrawal based on initial water right is built for the implementation of initial water right allocation scheme as well as unified allocation for allowable water withdrawal and sewage discharge.The model couples the water allocation simulation model and the computational model of permissible pol-lution bearing capacity.In view of the model complexity,a new technology which synthesizes system simulation,iterative reservoir turns...     

单扫描示波极谱法测定药物中头孢唑啉钠含量

在稀H2SO4介质中,头孢唑啉钠在滴汞电极上于-0.70 V(vs.SCE)处产生一灵敏的极谱还原峰,头孢唑啉钠的浓度在0.8~600μg/mL范围内与其所产生的峰电流呈线性关系,建立了用单扫描示波极谱法测定药物中头孢唑林钠含量的新方法,此方法检出限为0.41μg/mL。用于实际药品测定,结果与药典法一致。     

板坯连铸鼓肚变形行为分析

本文从平板理论出发,考虑高温蠕变,推导出坯壳在钢液静压力和温度场的共同作用下的挠度解;从鼓肚变形能出发,推导出计算拉坯阻力的解析模型;并通过工程实例和实测分析了最大鼓肚变形量和拉坯阻力计算的准确性。     

拉坯速度对结晶器内钢液流动和温度分布的影响

针对板坯连铸过程,建立了钢液流动、传热、凝固的三维耦合数值计算程序,计算分析了拉坯速度对结晶器内钢液的流动、凝固特征的影响.计算结果表明,拉坯速度对流动的影响主要表现在宏观速度的大小上,不会影响流动的形态.但对传热和凝固过程有重要影响,直接影响到凝固终点的位置.凝固终点的长度与拉坯速度成正比关系.     

齿轮箱轴断裂分析

采用化学成分分析、断口分析、金相检验和力学性能测试,对某齿轮箱轴发生断裂的原因进行了分析。结果表明：其断裂模式为疲劳断裂,起源于退刀槽尖角位置,直角退刀槽造成应力集中产生疲劳裂纹;而原材料的锻造和热处理工艺不合理,加速了轴的疲劳断裂。