SBAS星历改正数及UDRE参数生成算法分析

星基增强系统(satellite based augmentation system,SBAS)通过地球同步轨道卫星实时播发导航卫星星历改正数和完好性参数,以提升用户定位精度和完好性.采用最小方差法解算GPS星历改正数,利用卡方统计进行改正数完好性检核,并依据星历改正数方差-协方差信息计算SBAS用户差分距离误差(us...     

锚定式方钢管混凝土柱与钢梁节点抗震性能试验研究

通过低周反复加载试验对6个锚定式方钢管混凝土柱-H形钢梁节点进行了试验研究,研究了不同轴压比情况下节点的破坏模式、延性、耗能性能、强度及刚度退化等。试验结果表明,破坏之前节点具有良好的滞回性能、延性及耗能能力,满足现行抗震规范的要求。锚定式方钢管混凝土梁柱节点可以用于拉力较小的节点。文中提出了有关的设计建议。     

新型黏弹性阻尼器足尺性能试验研究

黏弹性阻尼器是一种典型的被动控制装置,它可以通过黏弹性材料的剪切滞回耗能起到提高结构阻尼和减小结构地震或风振响应的作用.自主研发了损失系数不小于0.5的黏弹性材料,并基于此材料研发了新型国产黏弹性阻尼器.通过对黏弹性阻尼器足尺试件进行不同应变幅值、加载频率工况下的基本力学性能试验、以及低周疲劳性能试验,研究了不同工况下...     

饱和砂性土流变模型的试验研究

正确合理的土体本构模型确定是地面沉降模拟的关键之一。上海和江苏地区多年来野外分层标的实际观测资料表明该区含水层系统砂层变形具有流变特征,表现出变形滞后于含水层水位变化的现象。本文基于粘弹性理论,选取了常州含水层系统原状砂性土样进行单轴压缩试验,分析了砂性土流变荷载曲线,并选择现有的相关本构模型进行识别,从而确定能更好反映研究区土体变形规律的流变模型。结果表明,研究区砂性土可采用Burgers模型进行描述,反演获得的4个流变参数随荷载的增加表现出一定的规律性。     

An Examination of Behavior and Hazards Faced by Physically Disabled People During the Loma Prieta Earthquake

There is a need to study hazards faced by physically disabled people during earthquakes. A literature review showed the importance of occupant behavior as a factor that contributes to casualty during earthquakes. A survey questionnaire was used to study the behavioral responses of 33 disabled residents, none of whom sustained injury, during the Loma Prieta earthquake of 17 October 1989. An occupant risk analysis methodology was developed to study the sequence of activities of the disabled people. Severe restrictions in the physical capabilities of the respondents did not appear to increase their exposure to hazards. Overall, the physically disabled occupants did not think of themselves as vulnerable, and those who felt vulnerable initiated self-protective action in response to the hazards present in their immediate surroundings.     

The frictional behavior of lizardite and antigorite serpentinites: Experiments,constitutive models,and implications for natural faults

Laboratory studies of the frictional behavior of rocks can provide important information about the strength and sliding stability of natural faults. We have conducted friction experiments on antigorite and lizardite serpentinites, rocks common to both continental and oceanic crustal faults. We conducted both velocity-step tests and timed-hold tests on bare surfaces and gouge layers of serpentinite at room temperature. We find that the coefficient of friction of lizardite serpentinite is quite low (0.15–0.35) and could explain the apparent low stresses observed on crustal transform faults, while that of antigorite serpentinite is comparable to other crustal rocks (0.50–0.85). The frictional behavior of both types of serpentinite is well described by a two-mechanism model combining state-variable-dominated behavior at high slip velocities and flow-dominated behavior at low velocities. The two-mechanism model is supported by data from velocity-step tests and timed-hold tests. The low velocity behavior of serpentinite is strongly rate strengthening and should result in stable fault creep on natural faults containing either antigorite or lizardite serpentinite.     

从铜的地球化学行为探讨常宁铜鼓塘富铜矿床的成因

常宁铜鼓塘富铜(银铀)矿床,以Ⅵ号主矿体为代表,具有以辉铜矿为主的矿物组合。本文根据Cu、(Ag)的地球化学行为,阐述了不同条件下,Cu、Fe与S、O的亲疏倾向,从而形成各矿体独具特色的矿物共生组合特征。进而讨论了矿床的特定成矿环境和典型岩溶成因。最后,笔者综合分析了多种有利成矿因素,指出金鸡岭背斜及其以北地段,是普查同类型富铜矿床的远景地区。     

地震前虎皮鹦鹉(Melopsittacus undelafus L.)叫声的模式识别

近年来,我国多数地震动物观察站(SAOS)监测虎皮鹦鹉(BG=budegerigar)的叫声频度与地震的关系,并取得了一些观测结果。但是,所用的声记录仪未能考虑BG叫声的声学特性,而不能分辨BG不同的叫声和进一步提取震兆性叫声模式(EPCP),并易受到环境噪声的干扰而产生误计数。 据此,分析了BG不同声行为叫声的声学特性。BG叫声大致上可分为单次叫声(SC)、变音调叫声(VTC)、单音节和多音节抗议叫声(MoSPC和MuSPC)。由此,进一步研制了它们的模式识别系统。该系统是以单片机为核心的微处理机,对BG叫声进行预处理、编码、分析、显示和打印输出。 观察结果表明,在高声场旅游飞机噪声(TAN)干扰下,该系统的BG叫声识别率(CRR)为66.7％,而对TAN没有误计数。在含10次不同声强的TAN干扰(432秒)的30分钟内,该系统记录了588次叫声(SC、VTC、MoSPC和SPC分别为377、22、20和169次),仅丢失65次叫声,其CRR平均为90％。但是,SAOS目前使用的声记录仪,这10次TAN干扰所产生的误计数可能约为BGU叫声的2.6—13倍。 由此可见,这种模式识别系统不仅可满足于BG不同叫声的识别,且具有良好的抗噪声功能。这就使之可为地震前BG声行为观测提供更有用的信息。不仅可给出BG叫声频度的昼夜节律变化与地震的关系,并可为揭示BG的EPCP提供一定的依据。     

虎皮鹦鹉夜叫声量异常与地震关系的分析

本文根据江苏省东台市Ｊｉａｎｇ港农场综合地震测报点微观观测虎皮鹦鹉的实验资料，详细介绍了１９８５年以来记录到的两次地震前鹦鹉异常反应。并对观测条件和方法、资料的可靠性、异常指标的确定，地震前兆异常与非震异常特征及其鉴别方法等分别作了介绍和讨论，还对动物的微观观测可能成为监视地震的一种有希望的短临前兆手段，进行了估评。     

弦支穹顶结构的抗震性能研究

弦支穹顶是一种受力性能优良的结构体系，它综合了单层网壳结构和索穹顶结构的优点，详细分析了影响弦支穹顶结构自振特性的各类参数，指出了边界条件对结构抗震性能的决定性影响。研究表明：当采用径向滑动边界时，即边界节点竖向和法向受到约束而容许径向在水平面滑动时，局部布索的弦支穹顶具有较佳的抗震性能；当边界条件相同时，弦支穹顶在水平地震和竖向地震作用下反应相似，只是程度上不同。