共查询到20条相似文献，搜索用时 593 毫秒
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通过马尔可夫分析,构造了求解系统处于平稳状态概率的迭代算法,提出了计算订单的平均缺货水平的近似表达式.数值模拟表明该近似表达式的计算结果与模拟结果非常接近,算法非常有效.数值实验还分析了合作与否以及零件的调拨策略对订单的平均缺货水平的影响. 相似文献
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本文研究基于max-min中继选择的双向中继系统的性能。首先推导了中断概率的精确表达式。为了清楚地反映中断概率与系统参数之间的关系,推导了一个中断概率下界闭合表达式。基于该下界得到了高信噪比下的中断概率渐进表达式。此外,还分析了系统平均误符号率的渐进表达式。根据分析结果得到max-min中继选择方式能获得满分集增益。最后MonteCarlo仿真实验验证了理论分析的正确性。本文的理论分析结果对系统设计和系统优化提供了理论基础。 相似文献
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本文从中缀表达式和后缀表达式在计算机处理中的优劣入手,针对中缀表达式到后缀表达式的转换算法,尤其是后缀表达式中多位数的算术运算的实现算法进行了探析. 相似文献
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本文从中缀表达式和后缀表达式在计算机处理中的优劣入手，针对中缀表达式到后缀表达式的转换算法，尤其是后缀表达式中多住数的算术运算的实现算法进行了探析。 相似文献
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在岩土体力学问题的数值模拟研究中,数值计算结果虽是定量的,但这种量化只是针对所确定的计算模型而言,它并不等于对原型的量化描述.岩土力学数值模拟中力学参数的选取是进行岩土力学数值模拟的关键,它直接决定了模拟结果的合理性,探讨力学参数对岩土数值模拟的影响具有非常重要的意义. 相似文献
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本文根据电力市场的交易规则,根据各机组出力和各线路潮流的关系建立了一个多元线性回归模型,利用Matlab软件求出每条线路上的潮流值关于各发电机组出力的的近似表达式,并对每一个表达式进行了误差分析,得出各表达式的复相关系数,回归效果显著。 相似文献
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本文利用系统动力学和ARIMA干预分析法,提出了一种新的供应链突变风险的测度方法。以包含一个制造商和一个零售商的二级供应链为研究对象,并在假设制造商与零售商之间的运输发生突变的基础上,根据对供应链系统反馈结构的分析结果,构建了供应链系统的动态仿真模型。然后,选取总库存、需求短缺量和总利润为供应链绩效指标,根据对仿真结果的描述性统计分析了运输突变风险对供应链绩效的影响。进一步,构建了供应链绩效指标的时间序列ARIMA模型,并利用干预分析法研究了测度运输突变风险的方法。研究表明,运输突变风险使得供应链的总库存平均每周期增加12.44%,需求短缺量平均每周期增加15.49%,而总利润平均每周期降低172.41%。 相似文献
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The integration of selling and fulfillment processes triggered by omni-channels is transforming the retailer’s operations management. In this context, there is a lack of research regarding the connection between digital and physical worlds in retail supply chains. This paper aims to propose a data-driven approach that combines machine-learning demand forecasting and operational planning simulation-based optimization to adaptively synchronize demand and supply in omni-channel retail supply chains. The findings are substantiated through the application of the approach in an omni-channel retail supply chain. The combination of clustering and neural networks improved demand forecast, supporting an assertive identification of demand volume and location. Simulation-based optimization allowed for the definition of which facility would serve identified demands most effectively. The approach reduced fulfillment lead time, mitigated backorders arising from incompatible product´s supply and demand, and lowered operational costs, which are key performance indicators in today’s competitive retail markets. 相似文献
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R＆D投资决策可靠性的熵（法）评价 总被引：5，自引：0，他引：5
将近代Ｓｈａｎｎｏｎ信息熵概念广义化,利用信息量的“可加性”性征及离散熵的一般表达式,与Ｒ＆Ｄ期望资金流贴现法相结合推导出Ｒ＆Ｄ资金流贴现率的熵近似上限及熵近似下限公式,用于Ｒ＆Ｄ决策评估,实例计算分析,得到令人满意的结果。中提出的理论,为寻求Ｒ＆Ｄ的决策方法开辟了新的途径。 相似文献
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《Journal of The Franklin Institute》2022,359(15):8243-8264
In this paper, the balanced truncation method is investigated for discrete time-delay systems. We show that the energy associated with the system controllability and observability can be characterized via the delay Lyapunov matrices, similar to the case of continuous time-delay systems. Then, we balance the system via a coordinate transformation in order to retain the delay structure of systems naturally. In this way, the balanced truncation method is conducted to obtain structure-preserving reduced models. Further, we provide an efficient process to compute a low-rank approximation to delay Lyapunov matrices based on the equivalent expression of discrete time-delay systems, which enables an approximate but fast execution of the proposed method. The stability of reduced models is also discussed in the paper. Finally, numerical examples are simulated to verify the feasibility and efficiency of the proposed method. 相似文献
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《Journal of The Franklin Institute》2023,360(10):6827-6845
Riccati differential equations are a class of first-order quadratic ordinary differential equations and have various applications in systems and control theory. In this study, we analyzed a switched Riccati differential equation driven by a Poisson-like stochastic signal. We specifically focused on computing the mean escape time of the switched Riccati differential equation. The contribution of this study is twofold. We first show that, under the assumption that the subsystems described as deterministic Riccati differential equations escape in finite time regardless of their initial state, the mean escape time of the switched Riccati differential equation admits a power series expression. To further expand the applicability of this result, we then present an approximate formula to compute the escape time of deterministic Riccati differential equations. Numerical simulations were performed to illustrate the obtained results. 相似文献
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Toshiyuki Sakata 《Journal of The Franklin Institute》1977,303(5):415-424
A reduction method is proposed for deriving an approximate formula for estimating the natural frequency of an orthotropic plate by using the results of an isotropic one. To justify the method, approximate formulae for estimating the natural frequency of clamped orthotropic rectangular and elliptical plates are derived from results previously reported for clamped isotropic rectangular and elliptical ones, respectively. The accuracy of the approximate formulae is discussed. 相似文献
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Solving initial-boundary value problems for systems of partial differential equations using neural networks and optimization techniques 总被引：1，自引：0，他引：1
A general system of the time-dependent partial differential equations containing several arbitrary initial and boundary conditions is considered. A hybrid method based on artificial neural networks, minimization techniques and collocation methods is proposed to determine a related approximate solution in a closed analytical form. The optimal values for the corresponding adjustable parameters are calculated. An accurate approximate solution is obtained, that works well for interior and exterior points of the original domain. Numerical efficiency and accuracy of the hybrid method are investigated by two-test problems including an initial value and a boundary value problem for the two-dimensional biharmonic equation. 相似文献
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星叶草叶脉序的形态学及其系统学意义 总被引：1，自引：0，他引：1
在星叶草叶二叉分枝脉序中，网结脉中2条完全汇合叶脉与靠近脉中完全分离叶脉间未发现任
何形式的维管束汇合的中间类型，相反观察到了网结脉中不同程度的连接脉退化的痕迹，因此网结脉不可能由靠近脉形成；盲脉的出现与齿的退化、网结脉中连接脉的间断及非网结脉由分枝处间断等相关；上述事实表明星叶草叶的二叉分枝脉序应为一减化性状。 相似文献