基于序贯蒙特卡洛算法的交通流事件重构

针对交通数据重构应用性差、缺乏对交通事件重构的研究等问题,结合交通流非线性非高斯的特点,提出一个基于序贯蒙特卡洛方法的交通流堵塞事件重构模型。该模型不断同化道路上的传感器数据,使仿真中的交通状态不断逼近真实路况,通过分析仿真数据以探测真实路网中存在的堵塞事件。模型能够对探测到的堵塞进行多粒子模拟来实现对真实道路上堵塞事件的重构。实验结果表明,该模型能够推测并重构出道路上的堵塞事件,对堵塞起始位置重构的平均误差为17m,对堵塞范围重构的平均覆盖率为82%。     

一种RFID复杂事件语义分析方法研究

复杂事件处理技术是射频识别技术（Radio Frequency Identification,RFID）应用中的重要技术。现有的RFID复杂事件处理模型,例如基于petri网的模型、基于树的模型、基于图的模型、基于自动机的模型,并不能十分有效地解决复杂的RFID应用问题,具体地说,RFID复杂事件的语义分析方面缺乏进一步的研究。针对上述问题,提出了一种RFID复杂事件语义分析方法。该方法,借鉴编译原理中的语义分析技术,为事件增添定义了继承属性和综合属性,同时按照事件之间的关系,定义了三种语义模式,最后通过一个语义解析算法,解析出了特定模式组合的语义信息。实验证实,该方法取得了比较理想的效果。     

适用于密集人群的异常事件实时检测方法

在密集人群场景下,针对现有异常检测算法在实时性和适用性方面的不足,提出了一种基于光流特征和卡尔曼滤波的实时检测方法。该方法首先提取图像的全局光流强度作为运动特征;然后对全局光流值进行卡尔曼滤波,并对残差进行分析;假设残差在正常状态下服从高斯分布,利用假设检验加以验证;运用最大似然(ML)估计得到残差的概率分布;在一定置信度下,确定正常状态的可信区间和异常状态的判定公式,并以此判断异常事件是否发生。实验结果表明,该方法对尺寸为320×240的视频,平均检测时间低至0.023 s/frame,且准确率可达95%以上。因而,该方法在保证较高检测率的同时,还具有良好的实时性。     

从位置参数入手直接建立圆点曲线方程

根据刚体四个有限位置的位移参数及点四位置共圆的等圆周角条件，列出了复极矢量等式．在刚体坐标系上，直接导出了圆点曲线方程，并给出圆点坐标的具体算法．     

Examining the Potential Fire Risk from a Short Duration Pyrotechnic Event

This study originated from trying to determine the fire risk from an armor piercing incendiary (API) passing close to flammable material. Since the temperature field produced by such a device was unknown the temperature distribution within the luminous region of a flash/fireball of laboratory-made cylindrical test charges of Barium Nitrate/Magnalium (Ba(NO₃)₂/Mg-Al) mixture, similar in composition to that of an API, was measured. The measurements have been acquired with 78.7 μm (40 gauge) high-speed K-type thermocouples that have an upper temperature limit of 1372°C. It was found that even though the thermocouples could not be located closer than 20 mm from the surface of the charges without failure, temperature differences of up to 350°C were recorded above the charge to that below. Furthermore, the heat release has a significant effect on the rate at which the temperature decays away from the surface of the charge, and this characterizes its pyrotechnic effect. In addition to the temperature measurements some image analysis has shown that the luminous region of the fireball was some 17 times larger than the charge itself, but the reaction zone was only a fraction of this size. Furthermore, this reaction zone was not as symmetrical as assumed and was probably due to an irregular burning process as the combustion wave traversed the test charge.     

桥梁工程中的极端事件探讨

在桥梁工程领域内探讨了极端事件的概念,介绍了作用于桥梁结构上的极端荷载--极端车流、地震、风暴、船撞、冲刷及其概率分析模型,以期能对桥梁工程中的极端事件形成明确认识,为下一步研究极端作用对桥梁设计的影响奠定基础.     

淠史杭灌区水稻干旱指标研究

本文利用多种方法,对试验资料进行分析,总结出适用于淠史杭灌区干旱评价的3种指标.     

A tribological study of an S–P–N containing additive in polyalphaolefin

The load‐carrying capacity, antiwear, and friction reduction properties of a novel S—P—N additive (BMDDP) added to a synthetic lubricant, polyalphaolefin (PAO), were evaluated using a four‐ball test machine. The results were compared with those of a commercial S—P—N additive (T307), and show that BMDDP is an excellent extreme pressure and antiwear additive in polyalphaolefin, similar to T307. The rubbed surfaces were investigated using X‐ray photoelectron spectroscopy, and the antiwear mechanism is discussed.     

二烷基二硫代磷酸锑添加剂的抗磨协同效应

利用四球试验机评价了二烷基二硫代磷酸锑（sbDDP）与含磷摩擦改进剂（TPO）、氯化石蜡（T301）、硫化异丁烯（T321）3种添加剂的极压和抗磨性能,以及它们之间的极压和抗磨协同作用;利用市售演示仪评价了SbD-DP、T301和T321之间的协同抗擦伤能力。结果表明：sbDDP和TPO、T301、T321分别体现出了不同程度的抗磨协同效果,其中以SbDDP和T301的协同效果最好;但在极压性能上,不仅没有产生协同作用,而且SbDDP和TPO复合后还表现出了对抗效应。另外,在抗擦伤能力上,sbDDP和T321表现出了较好的协同作用,而SbDDP和T301则表现出了对抗作用。然而当SbDDP和T301、T321复合使用后,不仅表现出很好的抗磨协同作用,而且表现出很好的抗擦伤能力,尤其当活性元素浓度达到最佳配比时,效果最为明显。     

Nonparametric estimation of the conditional tail index and extreme quantiles under random censoring

The estimation of the tail index and extreme quantiles of a heavy-tailed distribution is addressed when some covariate information is available and the data are randomly right-censored. Several estimators are constructed by combining a moving-window technique (for tackling the covariate information) and the inverse probability-of-censoring weighting method. The asymptotic normality of these estimators is established and their finite-sample properties are investigated via simulations. A comparison with alternative estimators is provided. Finally, the proposed methodology is illustrated on a medical dataset.