共查询到20条相似文献，搜索用时 390 毫秒
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B.Z. Kaplan 《Journal of The Franklin Institute》1981,311(5):299-309
A method has been presented in recent papers for deriving precisely stabilized waveform generators by relating them to second order conservative oscillators. The present paper demonstrates a method for modifying the previous models and in doing so a novel class of applicable oscillator models is established.Conditions that enable the models to sustain oscillations in steady state are described. A precise method for dynamically stabilizing the oscillators waveforms is developed, and practical uses are suggested. 相似文献
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渐近波形估计技术是近年来提出的一种求解宽带电磁散射问题的有效方法,本文将渐近波形估计技术应用到矩量法中,计算了二维随机分布的无耗介质柱的宽带雷达散射截面,计算结果与传统矩量法逐点计算的结果进行了比较,两者吻合良好,而计算效率得到了较大的提高。 相似文献
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通过高速质量块撞击炮口来推动火炮后坐是一种技术可行的火炮后坐模拟试验方法。为保证该模拟试验方法具有与实弹射击相似的后坐动态特性,基于ABAQUS软件建立了火炮模拟试验装置模型;通过对橡胶试样进行拉伸、压缩试验,得到橡胶材料的应力应变关系曲线,然后对其进行了材料评估;通过对小型橡胶波形发生器进行压缩试验,选取Ogden(N=1)模型作为试验装置中波形发生器对应的超弹性本构模型;对火炮试验装置的后坐动态特性进行了仿真研究,仿真结果与实弹射击的试验结果相吻合,验证了橡胶波形发生器的效果及该模拟试验方法的准确性。 相似文献
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《Journal of The Franklin Institute》2022,359(15):7775-7795
In this paper, an adaptive control strategy is proposed to address the synchronization issue for weakly damped generators under topological uncertainty. A singular perturbation analysis is then adopted for strongly damped generators and a compensation control scheme is subsequently given to maintain synchronization under topological changes. Theoretical proof is laid out for the validity of the proposed control scheme. Besides, a power sharing strategy is supplemented for strongly damped generators based on the designed controller. Finally, simulation studies are carried out to verify the effectiveness of the control strategies. Results show that synchronization can be swiftly restored even when the power grid suffers a fatal topological change. The power sharing property can be achieved under the given restriction with the proposed controller. 相似文献
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S. Abdelkader 《Journal of The Franklin Institute》2007,344(8):1063-1074
This paper presents a new method for calculating the individual generators’ shares in line flows, line losses and loads. The method is described and illustrated on active power flows, but it can be applied in the same way to reactive power flows.Starting from a power flow solution, the line flow matrix is formed. This matrix is used for identifying node types, tracing the power flow from generators downstream to loads, and to determine generators’ participation factors to lines and loads. Neither exhaustive search nor matrix inversion is required. Hence, the method is claimed to be the least computationally demanding amongst all of the similar methods. 相似文献
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采用Gröbner基方法,可以把一个在有限群作用下不变的多项式写成不变环的生成元的多项式.核心问题是如何有效地计算这个正维不变理想的Gröbner基.本文引入一个有效提升算法来计算这组Gröbner基.当用straight line program模型对整个计算过程进行复杂度分析时,可以把计算开销控制在多项式时间内. 相似文献
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采用Gr(o)bner基方法,可以把一个在有限群作用下不变的多项式写成不变环的生成元的多项式.核心问题是如何有效地计算这个正维不变理想的Gr(o)bner基.本文引入一个有效提升算法来计算这组Gr(o)bner基.当用straight line program模型对整个计算过程进行复杂度分析时,可以把计算开销控制在多项式时间内. 相似文献
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A.W. Simon 《Journal of The Franklin Institute》1944,237(3):177-196
A summary is given of the general quantitative theory of electrostatic generators in the final, simplified form, as progressively developed by the author in a number of previous papers. The method is illustrated by detailed application to (1) a four carrier, bisymmetric replenisher, (2) a six carrier, trisymmetric replenisher, (3) a four carrier, four symmetric, electrostatic alternator, and (4) a four carrier, bisymmetric, constant potential electrostatic generator. Various artifices for simplifying and shortening the labor of mathematical solution are given. 相似文献
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本文介绍了以EDA设计软件MAX PLUSII为基础,利用VHDL语言设计一个CRC(7,3)码编码器的基本方法,所设计的编码器可将任意3位信息位转换为7位CRC码,并给出了该编码器在MAX PLUSII软件平台下的仿真结果及所生成的可共享的CRC编码模块。 相似文献
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This paper deals with the problem of constrained stability and tracking of Takagi–Sugeno (T–S) fuzzy positive systems. Linear programming (LP) is used to insert the constraints in the design phase while imposing positivity in closed-loop. The theoretical results are applied to the buck DC–DC converter which is widely used in the photovoltaic generators. Based on the simulation results success of the method is shown for this application. 相似文献
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One challenge of generating a liquid aerosol is finding an efficient way to break up bulk amounts of the compound into micron-sized droplets. Traditional methods of aerosol generation focus on the principle of creating the liquid droplets by blowing air at high speed over or through a liquid. In this study, a novel micropump droplet generator (MDG) is proposed based on a microfluidics device to produce monodisperse droplets on demand (DoD). The micropump design was employed to both pump the fluid into the air and to encourage droplet breakup and aerosol formation. Computational simulation modeling of the new MDG was developed and validated with comparisons to experimental data for current generators. The device was found to produce an aerosol similar to a vibrating orifice DoD device. Most importantly, the input power required by the newly proposed device (MDG) was several orders of magnitude below existing DoD generators for a similar droplet output. Based on the simulation results obtained in comparison with current DoD generators, the MDG device performed effectively at higher frequencies, smaller nozzle diameters, and regardless of the liquid viscosity of the solution. 相似文献
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转子一向是发电机的重要部件,随着我国电力工业的发展,电力系统本身变得越来越庞大和复杂,为了确保发电厂的发电机组的可靠和经济地运行,保证转子的安全,如何防止和及时发现转子接地故障一直受到发电企业的广泛关注。今通过对两种不同冷却方式(包括双水内冷与空气循环风冷)的发电机转子对地电压测量问题的探讨,找出有效准确的测量方法,加强正常运行时对转子绝缘的监控。 相似文献
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Through the coupling of commutator machines, self-excited alternating power can be spontaneously generated with no external electrical excitations. Standard frequency- domain analysis is applied to the various equivalent circuits for each configuration. Conventional series and shunt self-excited generators are shown to have a single pole in the right-half s plane, indicating growing exponential solutions, whereas coupled generators are shown to have a pair of complex conjugate poles in the right-half s plane, indicating overstable modes, which oscillate as they grow, resulting in self-excited two-phase alternating power generation. Because of this interesting result, the analysis is extended to consider N-coupled generators which shows the existence of many overstable modes, resulting in multi-frequency, multi-phase power generation. The existence of electromechanical alternating self-excitation is demonstrated with the periodic speed reversals of a separately exited d.c. motor, which has its armature in series with the field and armature windings of a generator. Experimental results are presented which indicate that the linear circuit representation is appropriate for the onset and early time interval of these self-excited machines. The magnetic saturation characteristic limits the exponential growth so that a steady state results. These devices are of use in low-frequency, high-power applications, as well as serving as a model for other spontaneous mechanisms in nature. 相似文献
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《Journal of The Franklin Institute》2023,360(12):8550-8568
This paper studies the PWM control problem of a class of nonlinear systems. During a modulation period, the PWM control signal maintains a pulse waveform with tunable width and fixed magnitude. The PWM control only possesses finite states, and has relatively limited control capability. This causes the degradation of system performance, and even the instability when implementing into a nonlinear system. We will introduce a novel method to design both the state feedback stabilizer and the output feedback stabilizer for strict-feedback nonlinear systems via the PWM control. The system performance is analyzed in a novel framework and the stability criteria is derived to ensure the system convergence. At last, two examples are considered to illustrate the effectiveness of our proposed method. 相似文献
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同步发电机的运行状态在很大程度上与励磁系统有关。优良的励磁系统不仅可以保证发电机运行的可靠性和稳定性，而且还可以有效地提高发电机及其相关的电力系统的技术经济指标。起励控制是励磁控制中的一部分，它的控制方式有手动控制和自动控制两种方式。正常情况下，采用由PLC控制的自动控制方式，手动控制方式为自动控制出现故障时的备用方式。 相似文献
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Ivana Lapi&#x; Ana Lon
ar Vran
i&#x; Dsire Coen Herak Dunja Rogi&#x; 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2021,31(2)
This case report describes false shortening of activated partial thromboplastin time (aPTT) due to erroneous optical reading of the clotting point in the presence of unfractionated heparin (UFH), and a biphasic waveform. Activated partial thromboplastin time performed on a coagulometer with photo-optical detection yielded an ambiguous clotting curve characterized by an early and steady decrease in light transmittance throughout the whole measuring range, with the clotting point read at 65 seconds. Further investigations included measurement of aPTT by means of a mechanical clot detection method as well as determination of another heparin-sensitive coagulation assay, that is thrombin time (TT), both being unmeasurably prolonged (> 150 seconds). Communication with clinicians revealed that the patient was on continuous UFH therapy and had an underlying sepsis, with highly elevated C-reactive protein (289 mg/L). The aPTT measurements requested at three timepoints later during the same day revealed gradual aPTT shortening and unveiled a peculiar biphasic waveform pattern. In this case, unmeasurably prolonged aPTT due to UFH therapy was masked by a biphasic aPTT curve pattern making only the first slope of the biphasic waveform visible within the measuring range. The early decrease in plasma light transmittance mimicked optical changes related to clot formation, thus causing erroneous optical reading and yielding a falsely shortened aPTT. This case emphasizes that such a pattern should be carefully inspected, especially when a combination of a critically ill condition and UFH therapy is present, in order to prevent erroneous reporting of aPTT and potential adverse effects on patient care. 相似文献
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随着电子测试技术的不断发展,测试技术正向自动化、智能化、数字化和网络化的方向发展。其中数字滤波器作为测试技术的重要工具而被广泛使用在各个领域。本文设计的滤波器以LabVIEW软件为背景,设计一个能对采集数据波形进行相关处理,并实现相应的参数测量。虚拟滤波器主要包括五个模块:模拟信号的产生、波形的处理、信号的测量、波形的存储与回放、滤波后的波形保存。数据处理模块主要实现数字滤波和加窗函数处理两大功能,可以选择不同的滤波器和窗函数以适应不同的情况,参数的不同设置能够使信号频率不断变化。它是一种测试仪器和系统的概念相结合的软件,结合了测试技术和相应的专业知识。本文介绍了在LabVIEW实现虚拟滤波器测试信号的方法。 相似文献