Combined Elapsed Time and Matrix-Analytic Method for the Discrete Time GI/G/1 and GI X /G/1 Systems

In this paper, we show that the discrete GI/G/1 system can be easily analysed as a QBD process with infinite blocks by using the elapsed time approach in conjunction with the Matrix-geometric approach. The positive recurrence of the resulting Markov chain is more easily established when compared with the remaining time approach. The G-measure associated with this Markov chain has a special structure which is usefully exploited. Most importantly, we show that this approach can be extended to the analysis of the GI ^X /G/1 system. We also obtain the distributions of the queue length, busy period and waiting times under the FIFO rule. Exact results, based on computational approach, are obtained for the cases of input parameters with finite support – these situations are more commonly encountered in practical problems.     

A Regularly Preemptive Model and its Approximations

A regularly preemptive model D,MAP/D ₁,D ₂/1 is studied. Priority customers have constant inter-arrival times and constant service times. On the other hand, ordinary customers' arrivals follow a Markovian Arrival Process (MAP) with constant service times. Although this model can be formulated by using the piecewise Markov process, there remain some difficult problems on numerical calculations. In order to solve these problems, a novel approximation model MAP/MR/1 with Markov renewal services is proposed. These two queueing processes become different due to the existence of idle periods. Thus, a MAP/MR/1 queue with a general boundary condition is introduced. It is a model with the exceptional first service in each busy period. In particular, two special models are studied: one is a warm-up queue and the other is a cool-down queue. It can be proved that the waiting time of ordinary customers for the regular preemption model is stochastically smaller than the waiting time of the former model. On the other hand, it is stochastically larger than the waiting time of the latter model.     

Derivate des Borabenzols. 25 [1]. Methylbis(1-methylboratabenzol)indium: Synthese und Struktur. Ein Beispiel für die Variabilität weicher molekularer Strukturparameter unter dem Einfluß der Kristallgitterkräfte

Borabenzene Derivatives. 25 [1]. Methylbis(1-methylboratabenzene)indium: Synthesis and Structure. An Example for the Variability of Soft Structural Parameters in the Crystalline Environment The new boratabenzene derivative InMe(C₅H₅BMe)₂ has been synthesized from 2-(Me₃Sn)C₅H₅BMe and InMe₃. The compound proves fluxional on the nmr time scale with average C_2v symmetry in solution. An x-ray structure determination shows the existence of four molecules in the asymmetric unit differing mainly in the bonding geometry of the metal atoms with respect to the eight symmetrically independent boratabenzene ligands. Thus the dynamical behaviour in solution is reflected in the solid state by the soft structural parameters of the indium-ring coordination, with their variability exceeding the standard deviations of the corresponding individual observations by an order of magnitude.     

模式耦合理论在圆周对称长周期光纤光栅建模中的应用

长周期光纤光栅是不同于光纤Bragg光栅的一种光纤光栅器件 ,根据模式耦合理论 ,长周期光纤光栅表现为前向传播的纤芯导模和同向的各阶次包层模式之间的耦合。分析研究了长周期光纤光栅轴向的模场变化。忽略轴向的模式耦合以及包层模式之间的相互耦合作用 ,并认为折射率指数的调制只存在于纤芯中 ,建立了简化的长周期光纤光栅数学模型。对圆周对称轴向均匀型长周期光纤光栅谱特性进行了仿真 ,其结果与实验结果基本吻合 ,表明了简化的数学模型的合理性     

三线摆振动周期与角振幅的关系

本根据机械能守恒定律推出了三线摆的振动周期和角振幅的关系，并据该关系式讨论了角振幅对周期的影响以及角振幅的确定。     

MINIMUM PERIOD CONTROL PROBLEM FOR INFINITE DIMENSIONAL SYSTEM

ＭＩＮＩＭＵＭＰＥＲＩＯＤＣＯＮＴＲＯＬＰＲＯＢＬＥＭＦＯＲＩＮＦＩＮＩＴＥＤＩＭＥＮＳＩＯＮＡＬＳＹＳＴＥＭＰＡＨＬＩＰＩＮＧＬＩＸＵＮＪＩＮＧＭａｎｕｓｃｒｉｐｔｒｅｃｅｉｖｅｄＤｅｃｅｍｂｅｒ１２，１９９４．ＲｅｖｉｓｅｄＡｐｒｉｌ１６...     

高性能固化剂在天津软弱地基加固的应用

通过对高性能 (AS系列 )固化剂与水泥的对比试验 ,研究其在天津软弱地基加固中适用性和优越性 ,并得出一套实用的固化剂加固软土地基的施工设计参数     

SWEIA艾滋病毒传染模型及应用

人类免疫缺陷病毒(HIV)是一种严重威胁生命的病毒,感染艾滋病毒患者一般经历四个阶段:i)艾滋病毒阴性的窗口期(W);ii)阳性的无症状潜伏期(E);iii)有症状期(Ⅰ);以及iv)移除阶段(A).为深入研究艾滋病传播过程,建立SWEIA艾滋病毒传染模型,定义基本再生数,分析无病与地方病平衡点的存在性和局部稳定性,根据2004至2015年中国艾滋病患者数据,采用遗传算法对SWEIA模型中参数进行估计.通过对基本再生数敏感性分析以及模型数值随参数不同而产生的变化,揭示艾滋病窗口期的接触率是影响艾滋病流行的主要原因之一.     

弹性屈曲梁在参数激励下的倍周期分叉

考虑一端具有干摩擦的屈曲梁在轴向激励下的非线性振动系统，利用Ｆｌｏｑｕｅｔ理论和谐波平衡法，研究了系统中初始屈曲度、阻尼、频率、激励振幅等各种物理参数对１／２业谐共振情况下倍周期分叉的影响，其规律与以往的数值模拟结果具有很好的一致性。     

Stochastic Analysis of Macrodispersion in a Semi‐Confined Aquifer

In this paper, the macroscopic dispersion resulting from one and twodimensional flows through a semiconfined aquifer with spatially variable hydraulic conductivity K which is represented by a stationary (statistically homogeneous) random process is analyzed using the spectral representation technique. Stochastic fluctuation equations of the steady flow and solute transport are solved to construct the macroscopic dispersive flux and evaluate the resulting macrodispersivity tensor in terms of the leakage factor and input covariances describing the hydraulic conductivity in a semiconfined aquifer bounded by a leaky layer above and an impervious stratum below. The macrodispersivity tensor is studied using some convenient forms of the log hydraulic conductivity process. The sensitivity of the resulting macrodispersivity to the input covariances is discussed along with the influence of the leakage factor for both one and twodimensional flows. It is found that the longitudinal macrodispersivities are increased due to the presence of leakage, while the transverse macrodispersivities are reduced due to leakage.