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1.
无线射频识别技术(RFID)催生和促进了物联网(IoT)的发展。RFID原始数据的海量性和语义隐含性等特点对RFID数据处理提出了挑战,为此将复杂事件处理技术引入RFID数据处理中。把RFID数据定义为事件,按照给定的规则,检测出相应的复杂事件。现有基于树的复杂事件检测方法不支持事件的数值属性的条件约束,提出了一种RFID复杂事件描述规则和基于规则匹配的检测框架,能够高效地处理RFID数据流,在此基础上,进一步改进了RFID复杂事件检测方法(RCEDA),提高了时序约束下非自发事件的检测效率。  相似文献   

2.
张峰  路坤  徐廷学 《飞机设计》2010,30(1):64-68
事故树分析是安全系统工程中常用的一种分析方法,本文对某型舰载直升机系统的起落装置工作进行了原理分析,在此基础上建立了舰载直升机起落架收放系统的事故树,并根据各基本事件的发生概率,计算顶事件的发生概率。接着对各基本事件进行了结构重要度、概率重要度和关键重要度分析,进一步确定了系统的薄弱环节,从而确定了安全投资方向。  相似文献   

3.
太阳质子事件是对航天活动构成威胁的重要空间辐射环境事件,质子事件的长期预报对航天器防辐射设计具有重要的指导意义。通过分析最近的23太阳活动周数据,并对比21和22周相关资料,总结出了太阳质子事件分布的三段式特征,即质子事件与太阳活动周同步,呈11年周期变化,每一个周期中又可以划分为:上升期(前4年)、峰值期(中间4年)和下降期(最后3年),同时对每一个阶段的质子事件分布特征进行详细描述。在此基础上,对第24周的质子事件分布状况进行预测。  相似文献   

4.
为了保证游戏通信协议具有较好的状态同步和防欺骗能力,提出一种适合P2P MMOG的安全同步算法.该算法在防欺骗协议NEO中加入事件排序和基于事件关联的回滚机制,在保证更新信息安全交换的基础上,对游戏事件进行排序,并对迟到事件进行处理.实验结果表明,该算法保证了较好的回滚次数和响应时间,可以有效维护游戏状态的一致性.在防欺骗和游戏状态同步的基础上维护了游戏的公平性.  相似文献   

5.
采用模糊故障树分析法,对引起电液作动器输出不稳定的各个因素进行系统分析,并建立了故障树。应用专家评分法对无统计资料的故障进行了概率估计,阐述了转换成模糊数的途径,将所有的底事件发生的概率表示为三角模糊数。应用模糊数截集的方法,进而计算顶事件和各子系统的发生概率的置信区间和基本事件的模糊重要度,并指明了系统改进的方向,为大型复杂的作动器系统进行可靠性分析提供了参考。  相似文献   

6.
民用飞机共模故障分析方法研究   总被引:1,自引:0,他引:1  
共模故障是一种相依失效事件,该事件的存在增加了复杂系统的联合失效概率,降低了冗余系统的可靠度,给系统设备带来了巨大的安全隐患。论述了共模故障的基本概念,分析了产生共模故障的原因,给出了共模故障定性分析过程,分别提出了基于扩展故障树和马尔柯夫分析的共模故障失效概率计算方法,在安全性分析领域进行了有益的探索。  相似文献   

7.
老人缺乏经济保障是造成农村养老纠纷事件多发的根本原因,作者在分析农村老人缺乏经济保障原因的基础上,对解决农村老人经济保障问题的途径进行了探讨。  相似文献   

8.
支持产品设计自动化的动态求解机制   总被引:2,自引:0,他引:2  
在分析事件驱动的消息处理机制的基础上 ,论述了产品设计自动化系统中如何有效利用事件-状态 -动作控制方法 ;在分析离散元模型的基础上 ,研究了离散系统 ,给出了离散事件驱动的产品设计过程模型 ;最后讨论了离散事件系统中工程求解问题的动态行为。  相似文献   

9.
韩民政  饶寿期 《航空动力学报》1992,7(4):343-347,395
在动力学分析的基础上,对航空发动机高速球轴承进行了热分析。首先在润滑模型分析的基础上,对球轴承的生成热速率作了分析计算。通过对球轴承中复杂的传热关系研究,进而采用有限元法、系统平衡法和经验公式相结合的方法计算了球轴承系统的温度分布。在温度场计算中,对内热源的分配和边界条件的处理进行了深入研究。最后对某发动机主轴球轴承进行了计算,结果和606研究所提供的试验数据基本相符,其误差不大于百分之五。   相似文献   

10.
太阳质子事件通量的预测对航天器的抗辐射加固设计和宇航员的出舱活动具有重要意义。针对1年以下的中短期航天任务,对太阳活跃年和太阳平静年分别统计了太阳质子事件和大于10 Me V质子事件通量的发生概率,分析得到太阳质子事件通量分布基本符合对数正态分布。在此基础上,计算出了一定置信度下1年以下不同航天任务期内的质子事件通量分布,为执行中短期航天任务提供了太阳质子事件通量预测的依据。  相似文献   

11.
高斯型小波在APC识别中的应用   总被引:1,自引:0,他引:1  
研究了高斯型复小波时频分析方法用于人机耦合振荡(APC)探测的有效性和可行性。基于小波理论分析了高斯型复小波的时域和频域关系,构造了高斯型复小波滤波器。确定了一组识别APC的逻辑模型和参数,并对一起横向APC事件的记录数据进行了分析处理。结果表明,高斯型和双曲高斯型复小波变换都可较准确地探测出APC,但后者实时性更好。  相似文献   

12.
对于广义对流差分格式,本文应用两种方法(截断误差分析法及事后估计误差法)导出了使其误差最小的最优α值。和以前的方法不同,它们是从所研究的对流-扩散方程本身出发导得的,而无需事先知道方程的解析解。大量算例结果表明,截断误差分析法有很高的精度。事后估计误差法的误差,除个别点外,也都比一般格式的误差要小或者小得多。但是,对于复杂的问题,前者的应用可能会有困难,而后者却很易实现。  相似文献   

13.
针对复杂结构、机构可靠性分析中的隐式极限状态方程,建立了可以同时考虑基本变量和失效一安全状态随机模糊双重不确定性因素的广义响应面可靠性分析方法。该方法采用模糊基本变量的等效随机化变换,在不改变基本变量模糊分布的情况下,建立了基于有限元分析的复杂结构、机构多个随机一模糊基本变量情况下的广义响应面法,利用广义响应面函数和模糊随机事件概率的计算公式,定义了复杂结构、机构广义失效概率的计算公式,并给出了多个模式情况下体系同时考虑状态和基本变量随机模糊性的广义失效概率计算公式。在弹性连杆机构强度刚度多模式广义可靠性分析的应用算例说明了所提方法的合理性。  相似文献   

14.
Hydrodynamic Ram (HRAM) is a phenomenon that occurs when a high-kinetic energy object penetrates a fluid-filled container. The projectile transfers its momentum and kinetic energy through the fluid to the surrounding structure, increasing the risk of catastrophic failure and excessive structural damage. This is of particular concern in the design of wing fuel tanks for aircraft since it has been identified as one of the important factors in aircraft vulnerability. Usually the HRAM phenomenon is analyzed considering completely filled tanks, but its effect on partially filled containers should also be taken into account due to the fact that tanks use to be impacted under these conditions. In the present paper, the commercial finite element code LS-DYNA has been used to simulate an HRAM event created by a steel spherical projectile impacting a partially water-filled aluminium square tube. The ALE formulation is employed to reproduce the event. Experimental tests which indicate the pressure at different points of the fluid, displacement of the walls and cavity evolution for different impact velocities, are compared with the numerical results in order to assess the validity and accuracy of the ALE technique in reproducing such a complex phenomenon.  相似文献   

15.
Conclusion We have got a reasonably clear idea of the various forms under which the type IV continuum emission may appear. Also we can imagine what kind of processes come into play during a type IV event. But the insight gained so far applies to the general case. Individual cases are widely different, and we are still far from understanding why a given event behaves as it does. For instance, why are metric responses lacking at a certain big microwave outburst, or why is the decimetric component particularly strong or prolonged on certain occasions? One can imagine that such questions would receive an answer if one were allowed to see the configuration of magnetic lines of force above the activity region !Does the type IV event tell us a fine story of the interplay of energetic particles and streams of particles with coronal magnetic fields ? Maybe the story would be a fine one if the language could be understood. At present we know only a few words of it; for this reason to us the story is very fragmentary. First of all, however, the message should be recorded far more completely than has been done so far. The number of observations that should be made of one and the same event is tremendous; the program comprises:1) spectral observations from 1000 Mc/s down to the lowest frequencies; 2) single frequency observations at a great many wavelengths covering the whole radio spectrum; 3) measurements of polarization and 4) determinations of position and angular extent in at least every octave of the whole radio spectrum.Especially as regards the latter two points, the present situation is still very unsatisfactory, though good work has been done already in Japan. The realization of a complete recording of phenomena during a type IV event calls for a combined effort of several observatories.Very encouraging are the established relations between solar type IV events and terrestrial phenomena. From an analysis of solar cosmic ray events as recorded on several places on the earth, interesting inferences have been drawn regarding the travelling conditions of particles in interplanetary space (cf. Carmichael, 1962). Likewise, one may expect interesting information on the behaviour of interplanetary particle clouds of solar origin from (interferometric) observations of decametric radio emission on the occasion of type IV events.The occurrence of a major type IV event enables forecasters to predict successfully geomagnetic and ionospheric storms. Type IV events will determine at what times certain space research experiments will be launched in the next solar cycle. One should like to be able to indicate the probability for the occurrence of type IV solar radio flares themselves. It is known that these flares generally occur in complex sunspot groups; but a complex sunspot group does not of necessity imply the occurrence of a type IV flare. Observations of coronal condensations at microwave frequencies with a high resolution interferometer may help sorting out those centres of activity that are most likely to produce type IV flares.  相似文献   

16.
Following a solar flare in April 1979, a stream of ions and electrons appeared in interplanetary space for about 8 days. The ions follow a classic ESP pattern. Large fluxes of low energy (2–11 keV) electrons are also present throughout the event. Several distinct populations of these electrons can be identified in association with filaments of interplanetary magnetic field. The electron energy spectrum is remarkably well fit by a power law exponent -2.7 during most of the event.The pitch angle distribution of the low energy electrons are complex and undergo many changes. Weak pitch angle scattering and adiabatic effects play a role in shaping these distributions. The low energy electron fluxes increase following the strong interplanetary shock on 5 April 1979.An invited paper presented at STIP Workshop on Shock Waves in the Solar Corona and Interplanetary Space, 15–19 June, 1980, Smolenice, Czechoslovakia.Physics Department and Space Sciences Laboratory.Space Sciences Laboratory.  相似文献   

17.
为满足民用航空发动机的安全性目标,发动机顶层故障事件(顶事件)的风险应被控制至可接受状态。针对顶事件的风险控制要求,细化为顶事件的预期发生概率应被控制至可接受值以下。基于顶事件的预期发生概率要求,提出了从上到下分析导致顶事件发生的潜在原因并逐级建造故障树的方法,阐述了故障树分析的开展时机及作用。然后,对顶事件发生概率的计算进行了研究,通过考虑顶事件的飞行阶段影响因素、故障树最小割集及其概率、底事件失效率及其风险时间,提出了顶事件发生概率的计算模型。同时,结合示例对顶事件发生概率的计算模型进行了应用,以验证顶事件概率计算方法的可行性。提出顶事件概率计算模型,为发动机顶层故障事件风险控制要求提供有力的技术支撑。  相似文献   

18.
A study is conducted on a new airworthiness compliance verification method based on pilot-aircraft-environment complex system simulation. Verification scenarios are established by "block diagram" method based on airworthiness criteria. A pilotaircraft-environment complex model is set up and a virtual flight testing method based on connection of MATLAB/Simulink and Flightgear is proposed. Special researches are conducted on the modeling of pilot manipulation stochastic parameters and manipulation in critical situation. Unfavorable flight factors of certain scenario are analyzed, and reliability modeling of important system is researched. A distribution function of small probability event and the theory on risk probability measurement are studied. Nonlinear function is used to depict the relationship between the cumulative probability and the extremum of the critical parameter. A synthetic evaluation model is set up, modified genetic algorithm (MGA) is applied to ascertaining the distribution parameter in the model, and a more reasonable result is obtained. A clause about vehicle control functions (VCFs) verification in MIL-HDBK-516B is selected as an example to validate the practicability of the method.  相似文献   

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