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1.
定义并讨论了多状态多维可靠性系统关于流(F_t)的IFR、DFR、NBU和NWU等寿命分布类,同时还讨论了这种分布类关于独立和与极限运算的封闭性问题。  相似文献   

2.
负载分担下可修的并联系统模型   总被引:2,自引:0,他引:2  
提出了一个负载分担可修的并联系统模型,在系统中,n个并联部件是可修的,一个部件失效,将会导致剩余部件有更高的负载,从而引起更高的失效率,假定每个部件仅有2种状态;工作或失效,那么系统的状态过程是一个时齐的离散的马尔可夫链,它可以产生1列微分方程,借助于拉普拉斯逆变换可计算出该模型的主要可靠性指标-系统的可用度及可靠度,最后,以一个特例证明了本文的模型是并联系统的推广,同时也说明用本文的方法来计算负载分担可修的并联系统可靠性是切实可行的。  相似文献   

3.
可靠度最优分配问题是系统研制过程需要解决的一个重要问题。其目的是从整体出发将有限资源加以最有效利用。讨论了由九个相互独立的子系统串联而成,第j种子系统由白个相互独立的第歹种部件并联而成的系统可靠度最优分配问题。文中给出以上系统可靠度最优分配的改进算法,并应用于具体算例,说明计算次数有一定减少。  相似文献   

4.
对钢缆进行力学性能分析及可靠性建模,能够对其在使用过程中的可靠性进行评估.首先,通过将钢缆简化为并串联模型,考虑了Weibull效应和Daniels效应对其力学性能的影响;然后,应用次序统计量推导出具有Weibull效应的串联系统强度的Weibull分布表达式;其次,分析了具有Daniels效应的并联系统的强度计算公式和分布函数;最后,在不作钢丝失效独立的假设下,通过条件概率和分步计算对钢缆进行了可靠性建模.研究表明,所建立的钢缆类并串联系统可靠性模型能够为钢缆的可靠性分析提供依据,并且能反映相关失效的影响.  相似文献   

5.
一个可修复的串联系统,由k个不同元件组成。系统只有一个修理工,且第i个元件的工作时间和修复时间分别服从指数分布F_i(t)、G_i(t),i=1,2,…,k.同时假定每个元件在t时刻处于何状态(工作或修理)是相互独立的。计算具备上述条件的系统可用度及MTTR的置信水平为1-α的置信限。本文就此类问题分析,认为可用Easterling方法来计算,并在计算机上进行了数值模拟.  相似文献   

6.
10000kN液压机主缸液系统可靠度分配   总被引:1,自引:0,他引:1  
介绍了以相对失效率和相对失效概率法对串联,并联系统进行可靠度分配的基本步骤,按照此原则对10000kN液压机主缸液压系统进行可靠度分配,并提出提高系统可靠度的措施。  相似文献   

7.
本文将二值逻辑代数推广为多值逻辑代数,并提出了一种新的基于多值逻辑代数理论的多状态系统的分析方法。二状态情况下的串联和并联结构函数被推广到多状态情况;二状态分析中使用的故障树被推广为状态树。使用本文中所定义的多值逻辑代数能够很方便的处理其基本结构形式为串联和并联的多状态系统。作为本文提出的多值逻辑代数和分析方法的应用,文中最后简略分析了两种多状态系统;(1)由具有两类失效模式的元件组成的多状态系统;(2)考虑元件的性能水平和系统的性能水平的一种多状态系统。给出了计算这两种多状系统取某一状态概率的计算方法。  相似文献   

8.
用n维独立递增(轨道)的马氏过程刻划由n个独立件所构成的一个可修可靠性系统;以马氏过程关于某一状态集的首达时表示部件关于某临界状态的相对寿命;给出n个独立的马氏过程NBU特征的各种等价性条件及弱收敛的封闭性。证明在关联结构系统下,每一马氏过程的NBU性质推出关联结构过程的NBU性质,即部件寿命的NBU性质导致关联寿命函数的NBU性质;且推得关联寿命涵数是PH-分布。  相似文献   

9.
考虑了一个遭受2种类型风险的竞争风险模型。引入原因反向失效率来研究系统在某时刻x已经失效的条件下,在(x-dx,x]内由第i种原因导致失效的概率。基于原因反向失效率,给出系统寿命和失效原因相独立的充要条件。最后,研究了由第i种原因引起失效的系统在时刻x的休止时间的生存函数的性质。  相似文献   

10.
为了分析没有或仅有少量的历史故障数据的多部件竞争失效系统可靠性,同时考虑外界冲击对内部退化过程的影响,基于不确定理论分别建立串联竞争失效和并联竞争失效可靠性模型,并推导出相应的确信可靠度计算公式。通过一个微电子机械系统验证了模型的正确性和有效性。结果表明,外部冲击过程与内部磨损退化过程独立情形下的系统可靠度明显高于相依情形下的系统可靠度。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

15.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

16.
以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.  相似文献   

17.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

18.
Quality traits in wheat (Triticum aestirum L.) were studied by quantitative trait locus (QTL) analysis in a recombinant inbred line (RIL) population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross (ChSh). Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.  相似文献   

19.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

20.
赵英华 《科技信息》2008,(12):219-220
0.Preface China has long been boasting of its colorful and immense culture which comprises of Taoism,Confucianism and Buddhism.The interwoven influence among the religions on Chinese way of thinking,on the nation's behavior in their social life throughout the long history is beyond list.  相似文献   

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