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The grid current required to fire a thyratron has been shown to depend theoretically upon the shape of the grid current characteristic before firing as well as upon the grid circuit constants.The three-element FG-17 and the four-element FG-95 and FG-98 thyratrons have been investigated.Anomalies where excessively large grid currents were required to start the arc, occurring below certain values of temperature and plate potential, have been found and are described in some detail.Although the argon-filled FG-98 was found to be free from temperature effects over the operating range, positive shield grid potentials introduced anomalies at low plate potentials.Even though the plate and shield potentials and the temperature were kept within the recommended optimum range, it was found that for minimum grid currents at firing the negative grid impedance of these tubes necessitated a grid resistance of 100 to 1000 megohms. 相似文献
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Baris Gursu Author Vitae Melih Cevdet Ince Author Vitae 《Journal of The Franklin Institute》2009,346(8):768-783
In this paper, an optimum grounding grid that provides the conditions of GPR<Etouch and minimum cost in the structures of two-layer soil model is designed and the length of total conductor and the quantity of ground rod are calculated via Genetic Algorithms (GA). A new approach is presented for the calculation of total conductor length. At the same time, the subject regarding in which layer the ground conductors and rods that form the grounding grid in a substation are to be placed in two-layer soil is analysed using GA. With this as the goal, the depth of optimum grid burial is determined. Our study is compared with the design study for a two-layer soil model in the literature. As a result, the high performance of optimum grid design that is achieved using GA is emphasized by varied applications. 相似文献
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为探讨不同可再生能源渗透情形下的电网投资、再调度与可再生能源（renewable energy source,RES）削减需求,本研究提出一种连续的电力市场、网络模拟方法。市场模拟代表整个目标年电力交易日前市场每小时的市场清算过程,网络仿真代表了输电系统运营商为确保电力系统的安全性和可靠性,在确定常规电厂的最优再调度命令和RES的削减命令时所起的作用。通过市场模拟和网络模拟分别迭代计算成本效益和由可靠性驱动的输电网投资需求,该方法不仅可以研究RES的间歇特性所带来的网络约束,而且可以获得正确的规划和运行方案。此外,文章利用Benders分解技术和增广拉格朗日松弛法,在满足仿真约束的前提下,求解目标年的优化问题。最终,针对2030年罗马尼亚电力系统进行了案例分析,验证了所提方法的有效性。 相似文献
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Yi-Yuan Li Sara Ying Zhang Jason Zheng Jiang Simon Neild 《Journal of The Franklin Institute》2019,356(14):7836-7854
Vibration suppression capabilities of linear passive vibration absorbers, such as traditional tuned mass damper (TMD), and recently proposed inerter-based vibration absorbers, have been studied for multiple mechanical systems. In particular, significant performance advantages have been obtained with a specific device making use of both inerter and mass elements, namely the tuned mass damper inerter (TMDI). However, there are still countless mass-included inerter-based configurations that have not been studied, which can potentially provide more preferred dynamic properties. In this paper, an immittance-function-layout (IFL) is introduced, which can cover a large range of topological connection possibilities with both mass and inerter elements. With the recently proposed structural immittance format, a systematic approach is established to identify the most beneficial IFL type mass-included inerter-based configurations with pre-determined number of each element type. Vibration suppression performance with single-IFL type device and two parallel-connected IFLs (i.e. dual-IFL) type devices are investigated in this paper. Three optimal configurations are identified for mitigating the maximum inter-storey drift of an example 3-storey building model subjected to base excitation. With this 3-storey building model, results show that, for the optimum single-IFL configuration, the performance improvement is 7.3% compared with the optimum TMDI, and with identified beneficial dual-IFL configurations, up to 34.9% performance advantages are obtained. Furthermore, consistent performance gains are shown under real-life earthquake inputs and with a 10-storey building model using identified absorber configurations. 相似文献
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This paper mainly investigates the passive realization problems of bicubic (third-order) impedances as damper-spring-inerter networks consisting of no more than five elements. First, the special case where a bicubic impedance contains a pole or a zero on the imaginary axis or at infinity is discussed. Then, assuming that there is no pole or zero on the imaginary axis or at infinity, the realizations of bicubic impedances as five-element networks are investigated. Necessary and sufficient conditions for the realizability as five-element series-parallel networks and as five-element non-series-parallel networks are derived, respectively, where 22 series-parallel configurations and 11 non-series-parallel configurations are presented to cover the conditions. Finally, two numerical examples together with positive-real controller designs for a quarter-car suspension system are presented for illustrations. The results of this paper can contribute to the synthesis of low-complexity passive mechanical (or electrical) networks, which are motivated by the synthesis and design of inerter-based vibration control systems. 相似文献
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Olivier A. Bauchau 《Journal of The Franklin Institute》2010,347(1):53-68
Finite element based formulations for flexible multibody systems are becoming increasingly popular and as the complexity of the configurations to be treated increases, so does the computational cost. It seems natural to investigate the applicability of parallel processing to this type of problems; domain decomposition techniques have been used extensively for this purpose. In this approach, the computational domain is divided into non-overlapping sub-domains, and the continuity of the displacement field across sub-domain boundaries is enforced via the Lagrange multiplier technique. In the finite element literature, this approach is presented as a mathematical algorithm that enables parallel processing. In this paper, the divided system is viewed as a flexible multibody system, and the sub-domains are connected by kinematic constraints. Consequently, all the techniques applicable to the enforcement of constraints in multibody systems become applicable to the present problem. In particular, it is shown that a combination of the localized Lagrange multiplier technique with the augmented Lagrange formulation leads to interesting solution strategies. 相似文献
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Ibrahim Kocabas 《Journal of The Franklin Institute》2011,348(7):1339-1362
The Laplace transformation technique has been widely applied to modeling of tracer transport in oil and geothermal reservoirs, and in groundwater aquifers. However, mathematical models of many flow and transport problems could only be obtained as Laplace space solutions, and hence, their computations had to involve a numerical inversion technique.In this work, we employ the iterated Laplace transformation technique to develop novel closed form solutions to the tracer transport models in heterogeneous media. Two types of configurations have been considered: tracer transport in single fracture located in low-permeability matrix and tracer transport in a double porosity medium consisting of flowing and dead-end pore systems. In addition, both linear and radial flow geometries have been considered for both configurations. Applications of iterated Laplace transform technique to these four types of models are presented as fundamental examples and their numerical results were used as benchmarking for the numerical inversion results from Stehfest and Dubner and Abate algorithms.As the technique is quite versatile, we expect that the method should gain widespread acceptance to develop solutions to a wide range of problems in flow and transport in porous media and improve the application of nonlinear regression technique to these solutions.This work has achieved four important objectives: first, two novel Laplace transform relations that are useful in tracer studies are presented. Second, the present work serves to verify/invalidate the results of numerical inversion algorithms. In addition, it provides better insight into tracer transport mechanisms. Finally, it serves as a powerful tool of design and interpretation of tracer tests. All four objectives are illustrated in this work. 相似文献
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在检查者眼前放置交叉偏振片,通过旋转偏振片改变透射光的强度,赋于视野检查指标Amsler表阈值刺激,并改良Amsler表,使其检查范围为标准表的2倍,适用于青光眼患者的视野检查。对21例41眼青光眼分别用阈值刺激法和不用偏振片的改良Amsler表进行检查,二者比较具有非常显著的差异,同时采用平面视野检查法能够验证前者的结果。因此,交叉偏振片的使用能够有效地提高该项视野检查方法的敏感性。 相似文献
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近几年,图书情报领域在新技术应用研究方面可谓百花齐放,网格技术、数据挖掘技术、射频识别技术、RSS技术、存储技术、Web2.0、智能手机技术、聚类技术等技术的研究不断呈上升趋势。文章选择2006年至2012年图书情报领域核心期刊的研究论文进行统计与主题分析,发现不同技术主题的研究脉络,找出研究中存在的问题,以期对未来的研究工作提供一定的理论基础。 相似文献
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A general three-dimensional solution is presented for statics and dynamics of plates, homogeneous or laminated, of orthotropic materials. The solution is in series form. Using parts of the general solution a variety of problems, especially of rectangular configurations, can be solved. As Mindlin's approximate analysis for vibration of thick plates is often adequate for specific practical purposes, a general solution for Mindlin's analysis is also given. 相似文献
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Walton E. Williamson 《Journal of The Franklin Institute》1976,302(4):379-380
The paper describes methods of carrying out the minimum weight design of finned surfaces of various types. For each type of surface (flat, cylindrical, etc.) two cases are considered. First, a method is described by which it is possible to obtain the optimum surface profile of fins required to dissipate a certain amount of heat from the given surface, there being no restriction on the fin height. This analysis is then extended for the case when the fin height is given. The solutions are presented for a number of cases and the results are discussed to illustrate the importance of various parameters in the design. 相似文献
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S.G. Tzafestas 《Journal of The Franklin Institute》1980,309(6):399-438
In this paper a variety of optimal control (OC) problems for distributed- parameter (DP) systems are approached using mathematical programming (MP). First, the principal DP models in current use are given, a variety of DP objective functions is provided, and the OC problems based on them are formulated. Second, these models and objective functions are converted in algebraic form, as required by MP, and the solution procedure of the OC problems via MP is outlined. Third, a representative set of nonlinear programming results applied to DP systems is presented, and finally, a numvber of application examples is given. 相似文献
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在我国金融改革的进程中,由改革引起尚未解决的问题和触发的新问题日趋复杂。经济全球化以及当前国际金融危机的背景下,科学发展观对化解金融业存在的问题具有指导意义。文章从科学发展观的角度分析我国金融体系中存在的问题,深入探讨如何以科学发展观为指导实现我国金融业的全面协调和可持续发展,并提出了一些可行措施和建议。 相似文献
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A particular class of routing problems associated with demand actuated transportation systems requires the repeated regeneration of minimum or optimum routes as a part of the more general routing problem. The generation or regeneration of routes by methods other than classical minimum route solutions is discussed. A general system model for processing demands in a demand actuated transportation or routing system is presented and discussed. 相似文献
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Epple M 《Isis; an international review devoted to the history of science and its cultural influences》2011,102(3):481-493
In order to discuss the temporal structure of mathematical research, this essay offers four related definitions of a mathematical object from different times and places. It is argued that in order to appreciate the differences between these definitions, the historian needs to understand that none of them made sense in mathematical practice without a technical framework, referred to but not explained in the definitions themselves (an "epistemic configuration of research"); that the dynamics of the epistemic objects of mathematical research are secondary to the dynamics of these epistemic configurations as a whole; and that the dynamics of epistemic configurations of mathematical research do not follow law-like processes. Very different types of change may happen, and some of them link the dynamics of epistemic configurations with events and developments far beyond the bounds of the research field in question. These insights have historiographical consequences that require us to rethink the kind of temporality ascribed to mathematics. 相似文献