Performance analysis of Markovian polling systems with single buffers

In this paper, we analyze the Markovian polling system with single buffers, asymmetric arrival rates, service times, and switchover times. A virtual buffer model is introduced to derive the relationship of the joint generating function for the queue length of each station at a polling instant. The Laplace-Stieltjes transforms of the cycle time and the intervisit time are obtained from the marginal generating function. We analyze the cyclic, load-oriented-priority, and symmetric random polling schemes which are classified by adjusting the transition probabilities, and compare the merits and demerits of each scheme for the performance measures. In particular, we prove that the mean queue lengths at the polling instants are the same for all stations in case of the load-oriented-priority polling scheme for the buffer relaxation system in which a new message is stored as soon as the transmission of the message currently in the buffer is initiated.     

双三次B样条曲面生成的关键技术研究

B样条曲面在实际工程中得到了广泛应用。介绍一种双三次B样条曲面生成的改进算法,该算法能显著提高效率。提出B样条曲面正等测投影的建立方法,讨论用高性能的动态数组和Excel软件存储任意数量控制点的实现方法等关键技术。采用Visual C++6.0为编程工具开发软件系统,实现了任意数量控制点的双三次B样条曲面生成。     

桐子壕电站40MW灯泡贯流式水轮发电机组的研制

近年来,东方电机在成功制造30MW灯泡贯流式水轮发电机组的基础上试制了40MW灯泡贯流式水轮发电机组.这是目前国内自行研制的最大容量的灯泡贯流式水轮发电机组,其中采用的一些单项技术为今后发展更大容量灯泡贯流式水轮发电机组打下了基础.主要阐述东方电机在桐子壕3×40MW灯泡贯流式水轮发电机组的研制、工艺、计算等方面的主要特点以及电站运行情况.表3     

Could on-site fuel storage economically reduce power plant-gas grid dependence in pipeline constrained areas like New England?

In the Northeastern United States, natural gas supply constraints have led to periods when gas shortages have caused up to a quarter of all unscheduled power plant outages. Dual fuel oil/gas generators or local gas storage might mitigate gas supply shortages. We use historical power plant operational and availability data to develop a supply curve of the costs required for generators to mitigate fuel shortage failures in New England. Based on 2012–2018 data, we find that the historical fuel shortages at approximately 2 GW worth of gas-fired capacity could be mitigated using on-site fuel storage. For comparison, New England’s average reserve margin was 1.7–2.8 GW over our sample period. Oil dual fuel plants would recoup their investment if compensated with a reliability adder of $3−7/MWh during their normal operations, while $7−16/MWh would incentivize using on-site, compressed natural gas storage. We estimate that the capital expenses associated with the fuel storage options would be less expensive than installing battery backup for resource adequacy at current battery prices.     

基于分类的 ESGS 矛盾问题建模的研究

以往的可拓策略生成系统软件只能解决一类矛盾问题,通过分析已有矛盾问题建模方法及其不足,提出了一种基于分类思想的建模方法,并详细描述了矛盾问题分类建模的步骤,具体给出了分类建模所需库的建立方法,最后在软件中实现。实验结果表明,对某领域可拓策略生成系统中的矛盾问题进行分类,基本能够解决对该领域不同类矛盾问题的建模,实现了可拓策略生成系统问题输入界面的通用性,对可拓策略生成系统通用性的研究具有一定的现实意义。     

高度真实感三维图形的计算机生成

本文用光线跟踪技术在微机和光栅图形设备上生成高度真实感的三维图形。本文使用了考虑光在景物中的反射和透射且采用光谱计算的光谱整体光照明模型,对传统的光线跟踪算法作了改进;对光线跟踪自由曲线旋转面、光线跟踪N次Bézier柱面,光线跟踪反混淆等问题提出了新的方法。这些方法和传统方法相比有更少的时间复杂度,为在微机上实现光线跟踪较复杂物体提供了可能性。本文算法为计算机辅助几何设计,建筑设计,计算机动画提供了工具。     

改进粒子群算法在智能组卷系统中的应用

计算机智能组卷是近年来计算机在辅助教学中的一个重要应用,计算机智能组卷作为一种多目标求解的优化组合问题.提出基于灰色关联度分析的改进粒子群算法应用于自动组卷问题,并进行了仿真实验.仿真结果表明,此算法能够成功应用于自动组卷,组卷速度快、成功率高.     

新型分布式热电冷三联供系统应用

本系统采用天然气发电机组、溴化锂机组和地源热泵机组等组成高效的热电冷三联供系统。夏季,溴化锂机组和地源热泵机组产生的冷水汇总送至用冷区域用于制冷;冬季,发电机组冷却高低温循环水通过板式换热器产生与地源热泵机组和溴化锂机组品质相同的热水,汇总送至用热区域用于采暖。本文阐述了利用燃气内燃机发电的余热,带动溴化锂机组,结合地源热泵技术,提高了能源的梯级利用,满足了用户的能量需求,同时大幅度减少能源费用支出。     

关于驾驶室液压缸噪声及螺塞漏油的结构改进

介绍了驾驶室液压翻转机构的工作原理,并重点阐述了液压缸的结构改进。分析了液压缸原结构的缺点及产生噪声的原因,并对其进行了改进;通过改进前后试验数据对比表明,此结构有效消除了噪声及异响。针对液压缸磕碰漏油的故障,分析了原结构螺塞和铜垫圈密封的缺点,采用镶嵌式涂螺纹锁固胶的内六角螺塞结构彻底解决了磕碰漏油问题。     

非线性市场需求下机组优化出力的自适应动态古诺模型

该文运用博弈论及动态经济学方法首先给出了非线性反需求函数下电厂机组出力的静态古诺模型及古诺均衡的求解方法；然后引入机组自适应期望出力的概念，建立了求取下一生产周期电厂机组最佳出力的非线性自适应动态古诺模型。两种方法都反应了电厂追求利润最大化的博弈行为，因此能够作为电厂机组出力的优化决策工具。仿真结果表明自适应动态古诺模型是有效、可行的，而且其稳定值趋于古诺均衡。