差动保护运行动作特性的相量分析

差动保护的穿越制动特性依赖于制动电流的选取 ,每种制动方式有其自身的制动特性。不同方式之间如何比较 ,是需要有一种公用的方法 ,在同等条件下进行分析才行。提出用“运行动作特性”分析方法 ,直接以两侧电流的相量关系来表述动作特性 ,这样各种制动方式就可以有共同的基础。     

半刚性连接对框架结构性能的影响

本文将半刚性连接钢框架的主梁模型化为部分约束的梁单元,其单元刚度矩阵可用于半刚性连接钢框架的弹塑性分析。对半刚性连接钢框架的弹性、塑性和稳定性分析表明,框架的半刚性连接对结构性能有明显的不利影响。因此,在钢框架的分析和设计中,应考虑半刚性连接的影响。     

Long-term effects of legislation and local promotion of child restraint use in motor vehicles in Sweden

The main objective is to study long-term effects of legislation and promotion of child-restraint use in motor vehicles. Subgoals are to describe the level of restraint use in cars and changes in mortality and morbidity patterns in regard to differences among age groups and geographical areas (morbidity). The study areas were; ‘The First Four’, ‘The Six Counties’, ‘The Rest of Sweden’, and ‘Sweden as a whole’, and the population were two age groups — 0–6 and 7–14 years. The incidence of restraint use comes from observations of car-seat-belt usage. Outcome evaluation was based on hospital-discharge data 1978–1996 and mortality statistics 1970–1996. The level of restraint use for children in the front seat was 97% in 1988 and was equal to 1995. Mortality data shows a decrease of 2.8% on an average per year, 76% over the study period. A significant change over time in the two intervention areas was shown (annual changes of −2.8 and −1.8%), but not in the rest of Sweden. The local authorities that started early with preventive programs, such as safety seat loan schemes and those having an organised safety-promotion program showed a much better improvement than the rest of Sweden. There is a need for appropriate information for local action on childhood injury prevention to accompany national legislation.     

两极相约与狄拉克常数的确定(胁量力学初导Ⅲ)

定义宇宙系统的集体效应的表征量为宇宙主胁量。由二象性推理获得电子基态的直径。根据宇宙主胁量下的粒子稳定性条件,建立真空背景下的两极相约关系式,得到真空的密度,电子的形成外力,宇宙膨胀的动因,完整注释了狄拉克假设,确定了大集体效应常数D。(即狄拉克常数)。解释了真空负质量状态的维持机制—反来缚集体效应。     

一种有源共模EMI滤波技术研究

实现了一种用于开关电源的有源EMI共模滤波器方案,并在一个半桥电路的基础上应用这种方案,对整机做了EMI传导测试。分析与实验结果也验证了有源滤波器的使用对开关电源的共模传导干扰抑制的有效性。     

Influence of reinforcing bar type on autogenous shrinkage stress and bond behavior of ultra high performance fiber reinforced concrete

This study investigated the effects of reinforcing bar type and reinforcement ratio on the restrained shrinkage behaviors of ultra high performance fiber reinforced concrete (UHPFRC), including autogenous shrinkage stress, degree of restraint, and cracking potential. In addition, the influence of the type and embedment length of reinforcing bars on the bond behavior of UHPFRC was evaluated by performing pullout test. Three different reinforcing bars (deformed steel bar, round steel bar, and GFRP bar) were investigated in the restrained shrinkage and pullout tests. The GFRP bar exhibited the best performance in relation to the autogenous shrinkage stress, degree of restraint, and cracking potential because of its low stiffness. The highest bond strength was obtained for the deformed steel bar, and the bar yielding was observed when the bar embedment length of l_b = 2d_b was used. The round steel bar exhibited the poorest behaviors for both of the restrained shrinkage and pullout.     

超微重晶石特级粉制造工艺中的制氟防腐方法

研究并提出用稀盐酸、硼酸和反应助剂作为含有萤石、方解石杂质的重晶石粉体酸漂增白的新配方。新配方可以有效抑制氟化物对酸漂设备的腐蚀；生产的超微特级粉中的硫酸钡含量达９９％以上，产品白度（Ｒ４５７标）达９３。此种特级粉的各项技术指标均优于目前国内外同类粉体。     

混凝土重力坝振参数识别研究

基于最优控制解的理论，建立了引入先验约束条件的混凝土重力坝动态参数识别模型，提出了求解该模型的约束变尺度方法。以某大坝空库情形为例，在振动观测数据不完全的条件下，对动态材料参数识别方法进行考察。识别结果表明，约束变尺度方法不仅具有较高的计算精度和良好的数值稳定性，并且具有一定的抑制数据噪音的能力。在只有一阶圆频率和几个固定点处有一阶振型观测数据的情况下，可以可靠地识别出坝体混凝土基础岩石的动弹性模量。从而为识别混凝土坝体和岩石基础弹性常数提供了一条新的有效途径。     

基于模糊识别的励磁涌流二次谐波改进原理

分析了变压器差动保护中传统方案二次谐波原理存在的缺陷，在此基础上，引入模糊识别法对其进行改进。充分挖掘判据的自适应性，不再使用单一划线式的“一刀切”门槛阈值，更好地匹配三相差流间的关系，相互制衡，在综合隶属度判据中采用反时限特征和延时门槛，使改进后的模糊识别二次谐波判据效果更加理想。此判据原理简单，科学合理，易于实现，在动作速度和防误动方面都有很大的进步。     

全玻幕墙中玻璃肋稳定性的试验研究

近年来,全玻幕墙在大型公共建筑中得到广泛使用,玻璃肋稳定性问题也受到了工程界的广泛关注,然而现行规范中对玻璃肋稳定性的计算尚没有明确规定。文章进行11组不考虑侧向约束和10组考虑侧向约束的玻璃肋试件的稳定性试验,且考虑不同的玻璃肋厚度的影响,结果表明：玻璃肋承受面内荷载时总伴随平面外弯扭失稳,且侧向弯扭幅度随玻璃肋厚度的增加而显著减小。玻璃面板为玻璃肋长边提供的侧向约束作用显著,玻璃肋的承载力可提高1倍左右。