钦杭结合带加里东期榴闪岩超高压变质作用研究

对钦杭结合带首次发现的加里东期榴闪岩进行了详细的年代学、矿物学和变质作用研究。结果表明,榴闪岩的变质时代为454±4Ma,经历了早期角闪岩相进变质、中期榴辉岩相峰期变质和晚期角闪岩相退变质三个阶段,具顺时针P-T-t轨迹。早期角闪岩相进变质作用阶段的矿物共生组合为角闪石+斜长石+石英,温压条件分别为719℃~795℃和7.56Kpa~8.30Kpa;中期榴辉岩相峰期变质作用阶段的矿物共生组合为石榴子石+绿辉石(后期退变为透辉石+钠长石)±石英,温压条件分别为668℃~821℃和26.42Kpa~33.46Kpa;晚期角闪岩相退变质作用阶段的矿物共生组合为石榴子石+角闪岩+斜长石±石英(即榴闪岩),相应的温压条件分别为611℃~854℃和4.76Kpa~9.30Kpa。结合前人资料推断,区域内加里东期可能经历了榴辉岩相超高压变质→高温麻粒岩相退变质→角闪岩相退变质的演化过程。钦杭结合带首次厘定出加里东期超高压变质作用,表明华夏和扬子两大陆块碰撞拼合发生在加里东期。     

Analysis of a laser process for permanently degrading a photo-activated adhesive joint

A pulsed, laser process has been developed to reduce the permanent strength of photo-activated adhesive joints prior to work-piece de-bonding. The objective of this investigation was to gain insight into the relationships between carbon black content of the adhesive, laser delivery mode, heat transfer, and adhesive degradation. To do so, a variety of experiments were performed to characterize process sensitivity, radiation absorption within the adhesive joint, and thermal decomposition of the adhesive. In addition, heat transfer analysis was conducted to predict adhesive temperatures during the process.The results of this investigation indicate that the strength diminishment of an adhesive joint occurs after it has absorbed a train of high power pulses in rapid succession. The vast majority of strength diminishment occurs over a very narrow time window and is highly correlated to the rapid emission of gray smoke/vapor from the adhesive joint. For this to occur, the adhesive must contain carbon black. It is also highly correlated to a rapid increase in temperatures throughout the adhesive matrix. Laser pulse parameters that do not lead to this rapid increase, will not initiate adhesive degradation.The inclusion of carbon black into the adhesive promotes heat absorption and increased temperatures in the adhesive joint. These temperatures are large enough to enable adhesive decomposition. But the time span over which this happens is too small for significant damage to occur. It is currently hypothesized that high temperatures local to the carbon black particles may be the source of adhesive degradation.     

可靠性鉴定试验受试样品的软硬件联合测试技术

为了研究一种可靠性鉴定试验中受试样品的软硬件联合测试方法,首先总结了软硬件联合测试的目的、对象、实施时机及传统测试需要的改进之处和可借鉴之处,进一步研究了软硬件联合测试与传统可靠性试验的关系。然后在考查软件与硬件测试结合的基础上,提出了两层结构立体测试运行剖面的方法,即利用子剖面与环境剖面的对应关系建立软件测试与硬件测试的联系,将两种测试统一在同一时间轴上,得出了软硬件联合测试的一般流程。     

清水江水质评价与变化趋势的显著性分析研究

以贵州省黔南州清水江监测数据为例,采用五元联系数方法进行水质评价.分析表明,该方法是一种客观有效的评价方法,评价茶园、兴仁桥两个断面均优于环境规划类等级.针对TP、氟化物指标浓度严重超标问题,采用Daniel趋势检验法测试2006年-2010年指标浓度变化的显著性,结果说明：5年内清水江重安江大桥河段TP、氟化物浓度降低的趋势显著性较高;而兴仁桥河段TP浓度降低的趋势显著性偏低;氟化物浓度几乎不变,变化不显著.由此说明,黔南州清水江水质得到改善.     

Copula-Based Bivariate Return Period Analysis and Its Implication to Hydrological Design Event

In univariate frequency analysis, the return period of an event has a one-to-one correspondence with its characteristic value, and the response of the hydraulic structure to hydrological load expressed by the hydrological event is monotonic. Thus, the design criteria of the hydraulic structure can be equivalently represented by the return period of the hydrological event, and consequently, design event-based design parameters evaluated have been widely used in practical engineering. However, the monotonic correspondence between the return period of the hydrological event and the response of the hydraulic structure does not exist in the multivariate context, and hydrological load with a larger joint return period does not always produce a more unsafe response. Misunderstandings of concepts of return periods of hydrological event, and estimation of hydrological design events usually take place in multivariate frequency analysis. This study theoretically derives the relations between different types of joint return periods, joint return period and its marginal return periods, the occurrence of bivariate extreme events and their return periods, and then the theoretical framework is tested. Results from the case contribute to the understanding of bivariate return periods of hydrological event, and the results demonstrate that design criteria cannot be equivalently represented by joint return periods of hydrological load, and design parameters of the hydraulic structure should not be determined by multivariate hydrological design events.     

ECONOMICS AND FEDERAL WATER PROJECTS1

While the science of economics is widely used in Federal water resource development projects, the usual procedure of applying an analytical discipline to arrive at a conclusion is reversed. The “answer” is usually provided ahead of time and economics is assigned the task of justifying the preconceived conclusion. This leads to a series of mitigatory effects in which economics as a science is not allowed to freely function. This article attempts to illustrate some of these “unusual” uses of economics in Federal water projects and note the “answers” we would logically expect from the economic discipline. Even though the theory of economics is often subverted, there are positive aspects to the role of economics in evaluating Federal water projects.     

低压电网中电力设备保护方式的安全性评价及其对策

对低压电网中电力设备选择接地保护或接零保护时的安全性进行了评价，并针对存在问题提出了改善措施     

液化石油气管线波纹补偿器爆裂事故分析

波纹补偿器爆裂事故，经济损失严重。用事故树方法进行定性分析，找出发生事故的主要原因，从安全设施、生产管理、安全管理方面采取防范措施，防止事故的重复发生。     

钢轨接头轨缝值和行车速度对轮轨垂向振动的影响

为了分析轨缝值与行车速度对车辆通过钢轨接头时产生的振动与噪声的影响程度,利用有限元方法,建立了车辆—轨道垂向耦合动力计算模型;该模型的车辆采用整车模型,共10个自由度;轨道结构采用3层弹性点支承有限长欧拉梁模型,共402个自由度;系统的激励大小可由轨缝值和行车速度推导出来,并运用赫兹非线性接触理论计算轮轨之间的相互作用力。采用该模型,结合快速显式迭代积分法和MATLAB6.5强大的矩阵分析功能,对不同轨缝值和车辆行驶速度条件下钢轨接头的动力响应进行了计算,为减振降噪提供理论依据。     

关于地铁轴流风机叶片发生断裂和出现裂纹的分析

叶片断裂和裂纹是旋转机械中普遍存在的一种安全隐患。对其发生规律进行分析是十分重要的。笔者针对地铁通风系统的某型号 18#轴流式风机发生断裂和出现裂纹的情况 ,采用Star—CD流体计算软件和ANSYS有限元软件计算了有、无软连接两种情况下的风机内流场和风机叶片的内应力。结果表明 ,软连接结构虽然对风机的内流场和叶片内应力有影响 ,但不足以对风机安全运行构成威胁。同时 ,分析了导致叶片断裂和出现裂纹的多种因素 ,并提出了避免类似现象发生的若干建议。