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1.
In order to ascertain the distribution of flow depth and veloctiy of debris flow,the the combination of numerical modeling and the GIS technology has been used to simulate the movement process of debris flow out of the outlet .The main model of momentum classification of risk zoning of debris flow is Z=Khv,Based on the distribution of the veloctiy and depth of debris flow ,the ditribution of momentum can be ascertained.Thereby the classification of risk zoning of debris flow can be worked out ,A case study of Chacatio Valley in Caracas,Venezuela,is presented to illus-trate the application of the method.  相似文献   

2.
One key function of intelligent transportation systems is to automatically detect abnormal traffic phenomena and to help further investigations of the cause of the abnormality. This paper describes a robust principal components analysis (RPCA)-based abnormal traffic flow pattern isolation and loop detector fault detection method. The results show that RPCA is a useful tool to distinguish regular traffic flow from abnormal traffic flow patterns caused by accidents and loop detector faults. This approach gives an effective traffic flow data pre-processing method to reduce the human effort in finding potential loop detector faults. The method can also be used to further investigate the causes of the abnormality.  相似文献   

3.
Numerical simulations of granular flows in rotating drums operated at medium to high rates (Fr=0.1― 0.2) have been carried out by using a Molecular Dynamics (MD) algorithm that incorporates inelastic particle interactions, sliding friction and rolling friction. The results indicate that the behavior of granular flow in rotating drums can be classified into two distinct zones: a shear active layer at the bed surface and a quasi-static plug flow region adjacent to the wall. The residence time of a tracer particle in the active layer is approximately a third or a half of that in the plug flow region. The thickness of the active layer at mid-chord is about 0.57―0.61 times that of the plug flow region. It is found that all cases simulated in this work are in the rolling-cascading intermediate regime instead of the pure rolling re-gime. The simulated tangential velocity at the mid-chord is also compared with experimental results reported in the literature and good agreement has been obtained. Based on the MD simulations and experimental results, a continuum approach has also been developed. It is shown that the behavior of granular solids in the plug flow region experiences plastic deformation along the radial direction from the wall with the velocity profiles well described by an exponential function, whereas the active layer velocity follows a simple expression for the Couette shear flow. Discussion has also been made on the granular temperature and concentration profiles.  相似文献   

4.
5.
Aiming at the problem of high computational complexity of Vertical-BLAST(V-BLAST) algorithm in Multiple-Input Multiple-Output-Orthogonal Frequency Division Multiplexing(MIMO-OFDM) system signal detection, this paper first uses Sorted QR Decomposition(SQRD) iterative operation instead of matrix inversion to reduce the computational complexity of the algorithm, and then considering that the algorithm is greatly affected by noise, Minimum Mean Square Error(MMSE) criterion is used to weaken the noise effect. At the same time, in order to reduce the noise and computational complexity, MMSE and SQRD are combined, which can not only reduce the noise and computational complexity, but also obtain the sub-optimal detection order, thus improving the detection performance of the MIMO-OFDM system. Finally, the numerical simulation of the MMSE-SQRD detection algorithm is carried out. The results show that the Eb/No of MMSE-SQRD algorithm is 2 dB greater than that of the MMSE algorithm and the computational complexity is O(N_T~3) under the conditions that N_T =N_R=2 and the BER is 10~(–2). The detection algorithm satisfies the demand of short wave and wideband wireless communication.  相似文献   

6.
The cellular automata (CA) micro-simulation model was used to describe the behavior of the mixed traffic flows at crosswalks where the pedestrians compete with the vehicles to cross the roadway. The focus of this paper is the behavior of pedestrians and the influence of pedestrians’ behavior on the vehicle flow, pedestrian flows, and the vehicle waiting time. The proportion of pedestrians who do not obey traffic laws, the group effect, and expected waiting time of pedestrians, regarded as the most important pedestrian characteristics, are taken into consideration in the analysis. Simulation results show the ability of the micro-simulation to capture the most important features of mixed traffic flow.  相似文献   

7.
In this study,photovoltage technique is applied in the development of a monolithically integrated sensor for redox(reduction–oxidation)potential and pH measurement.The sensor employs the electrolyte–insulator–semiconductor structure,with deposition of a layer of gold metal on partial surface of insulator silicon dioxide.Silicon dioxide and gold layer on a single chip form two distinct sensing sites,by sharing the same measuring system,the detection of redox potential and pH variation can be realized.In this work,the sensor characteristics is tested,and the sensitivity for redox potential and pH measurement is53.8 mV/log([Fe(II)]/[Fe(III)])and 44.3 mV/pH respectively.To demonstrate the validity of the sensor in extracellular detection,neonatal rat kidney cells are cultured on the sensor surface and then packaged in a flow chamber,thus the acidification rate of metabolites and the redox potential variation in extracellular microenvironment can be continuously monitored.Experimental results indicate increasing acidification and reducing potentials under physiological conditions.The synthesis parameters have potentials in detail revelation of cell metabolism.  相似文献   

8.
Electrochemiluminescence (ECL) is a highsensitive detection method with broad biological applications.Ruthenium (Ⅱ) tris (bipyridyl) (Ru(bpy)3^2 ) and tripropylamine (TPA) are most commomly used combination of the reactive species in ECL. The redox of Ru(bpy)3^2 with excess TPA at the surface of an electrode produces a highly efficient and stable light emission due to a rapid cycle of the reactions. This rapid, highly sensitive and accurate method has been applied to gene quantification. In this work, an ECL detection system is designed and applied in detection of presenilin-1 (PS-1) gene mutation. The results show that given the same polymerase chain reaction (PCR) cycle number, the ECL intensities from the digested and the undigested wild-type samples are nearly identical, but the difference in ECL intensities between the digested and the undigested mutant samples is distinctive. This detection technology connects PCR with ECL and allows a reliable discrimination between the wild-type and the mutant genes.  相似文献   

9.
Ore particles, especially fine interlayers, commonly segregate in heap stacking, leading to undesirable flow paths and changeable flow velocity fields of packed beds. Computed tomography (CT), COMSOL Multiphysics, and MATLAB were utilized to quantify pore structures and visualize flow behavior inside packed beds with segregated fine interlayers. The formation of fine interlayers was accompanied with the segregation of particles in packed beds. Fine particles reached the upper position of the packed beds during stacking. CT revealed that the average porosity of fine interlayers (24.21%) was significantly lower than that of the heap packed by coarse ores (37.42%), which directly affected the formation of flow paths. Specifically, the potential flow paths in the internal regions of fine interlayers were undeveloped. Fluid flowed and bypassed the fine interlayers and along the sides of the packed beds. Flow velocity also indicated that the flow paths easily gathered in the pore throat where flow velocity (1.8 × 10?5 m/s) suddenly increased. Fluid stagnant regions with a flow velocity lower than 0.2 × 10?5 m/s appeared in flow paths with a large diameter.  相似文献   

10.
Ore particles, especially fine interlayers, commonly segregate in heap stacking, leading to undesirable flow paths and changeable flow velocity fields of packed beds. Computed tomography(CT), COMSOL Multiphysics, and MATLAB were utilized to quantify pore structures and visualize flow behavior inside packed beds with segregated fine interlayers. The formation of fine interlayers was accompanied with the segregation of particles in packed beds. Fine particles reached the upper position of the packed beds during stacking. CT revealed that the average porosity of fine interlayers(24.21%) was significantly lower than that of the heap packed by coarse ores(37.42%), which directly affected the formation of flow paths. Specifically, the potential flow paths in the internal regions of fine interlayers were undeveloped. Fluid flowed and bypassed the fine interlayers and along the sides of the packed beds. Flow velocity also indicated that the flow paths easily gathered in the pore throat where flow velocity(1.8 × 10-5 m/s) suddenly increased. Fluid stagnant regions with a flow velocity lower than 0.2 × 10-5 m/s appeared in flow paths with a large diameter.  相似文献   

11.
针对采煤机调高液压系统中调高泵故障很大程度依赖于设计者和用户的知识和经验水平,提出一种基于隐半马尔科夫模型(Hidden Semi-Markov Model,HSMM)的故障预测方法。首先,对采煤机调高液压系统中调高泵压力、流量,调高油缸活塞杆速度、位移进行时域分析。然后,通过对特征值进行K-均值聚类分析确定隐状态数。最后,通过MATLAB和Python编程实现调高泵HSMM故障预测。结果表明:与基于隐马尔可夫模型(Hidden Markov Model,HMM)预测方法相比,调高泵早期故障、后期故障和灾变故障测试样本的预测结果识别率分别提高了10%、5%、20%,基于HSMM的调高泵磨损故障预测方法具有可行性。  相似文献   

12.
基于时变状态转移隐半马尔科夫模型的寿命预测   总被引:1,自引:0,他引:1  
隐半马尔科夫模型在进行系统状态估计及寿命预测时,其状态转移概率矩阵是固定值,得到的剩余寿命预测值呈阶梯状变化,与系统的实际剩余寿命值之间存在着较大的误差.针对上述问题,提出了具有时变状态转移概率矩阵的隐半马尔科夫模型,根据系统的3种典型退化状态分析,给出3种不同的状态转移系数.与初始状态转移矩阵相结合,得到随时间变化的状态转移矩阵.提高系统在当前健康状态下的剩余持续时间估计精度,最终得到更为准确的总体剩余寿命预测值.结果表明,基于时变状态转移概率矩阵的隐半马尔科夫模型相比传统的隐半马尔科夫模型,可显著提高剩余寿命预测的准确性.  相似文献   

13.
针对安全态势评估领域的权限有效性评估指标, 融合网络流量、入侵检测系统(IDS)报警和扫描信息, 提出一种全新的权限有效性定量评估方法.该方法将用户权限作为安全目标, 基于网络会话构建威胁用户权限的入侵迹, 并使用Markov数学模型度量安全目标失败的平均入侵代价, 进而定量评估权限有效性. 实验结果表明,当系统遭受缓冲区溢出攻击时, 权限有效性指数接近于0.该方法能够实时评估缓冲区溢出攻击对系统权限有效性的威胁,有效监控黑客行为引起的系统安全态势变化. 与其他评估方法相比, 该方法考虑了报警之间的因果关系,降低了IDS误报以及无效入侵信息对安全态势评估精度的影响, 有助于管理员了解黑客入侵步骤、决策系统安全状况以及识别高危险的入侵路径.  相似文献   

14.
针对现有网络安全技术的缺陷,将生命医学中的免疫赦免原理引入到入侵检测领域,提出了入侵免疫赦免的概念,给出了入侵免疫赦免系统模型及其各个功能模块的形式化定义,并说明了构建该模型时所需要的技术与机制.重点研究了入侵免疫赦免系统的赦免机制及原理,并给出了一个与免疫机制协同工作的入侵赦免触发器(赦免植入Agent,IPAT).  相似文献   

15.
基于热轧轧机HSMM模型建立了与某钢厂实际热轧生产线相一致的虚拟生产线. 以B510L钢为研究对象,分析了不同加热温度、终轧温度和卷取温度下所能获得的铁素体晶粒尺寸及相应的力学性能,并在此基础上为该钢厂提出了生产6.4mm厚B510L带钢的最佳工艺参数.  相似文献   

16.
针对管理信息系统的应用模式,讨论了如何根据不同的应用模式选择信息系统的权限管理方法.并在已有权限管理方式的基础上提出根据应用程序中各个功能模块使用的数据库实体来定义具体用户的数据库访问权限,同时将应用系统的模块权限和数据库系统权限有机的结合起来,从而达到简便、准确、高可用的信息系统权限管理方案.  相似文献   

17.
针对现有的基于身份加密(identity based encryption, IBE)体系中缺乏权限管理问题, 提出一种基于信任服务IBE体系下的权限管理方案. 该方案采用门限的思想和算法对服务进行集中管理, 并结合基于角色的访问控制管理权限, 实现了细粒度的权限管理. 采用信任继承的思想为用户分配角色, 并采用集中审计的思想维护系统, 提高了系统的可靠性.  相似文献   

18.
论沉默权及其法价值   总被引:6,自引:0,他引:6  
通过对沉默权由来的叙述,分析了沉默权在我国的法实践和障碍,揭示了沉默权在刑事诉讼中的法价值。  相似文献   

19.
.NET环境下基于角色的权限管理方案设计   总被引:2,自引:0,他引:2  
针对开发“煤矿安全隐患识别、预警与整改控制信息平台”的需要,设计了一个在.NET环境下基于角色的权限管理方案。通过分析传统权限控制设计中存在的问题和不足,结合基于角色的访问控制的原理,提出的权限控制系统利用模块编码、页面编码、功能编码和数据库的灵活设计来实现权限的控制。该方案实现了页面级别和页面内功能级别的权限控制,很好的解决了传统权限控制设计的不足,大大的提高了系统的灵活性和可扩展性,并且已经把它作为一个组件实现,可以应用于多种MIS系统的权限管理。  相似文献   

20.
权限控制是软件系统安全性的重要组成部分,通过借鉴RBAC的基本原理,实现了权限管理系统的设计及应用,大大降低了系统权限管理的复杂性,提高了权限管理的效率。  相似文献   

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