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观测数据的系统差是影响卫星定轨精度的主要因素,其中卫星转发器时延由于难以直接在轨测量获取,因此成为FY-4A静止气象卫星观测数据系统差的主要来源之一.针对该问题,首先对原有的FY 4A静止气象卫星转发器时延在轨标定方案进行了介绍并分析,发现该方案由于待估参数过多导致无法获得卫星转发器时延,随后提出了一种新的在轨标定方法... 相似文献
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为了在地面测试星载太阳辐射监测仪在轨对日跟踪性能,设计了太阳辐射监测仪跟踪引导系统.研究了太阳方位矢量在太阳辐射监测仪本体坐标系中的角度变化,通过坐标转化计算出其变化量及变化趋势,在此基础上提出了两轴联动二维度的引导方法.基于太阳敏感器工作原理,构建了跟踪引导模型,并给出了跟踪精度要求.最后利用跟踪引导机构和电控系统组成的跟踪引导系统引导太阳辐射监测仪进行了跟踪实验.实验结果表明:太阳辐射监测仪跟踪过程无断点,俯仰方向连续跟踪夹角小于0.07°,偏航方向小于0.04°,合成跟踪精度优于0.09°.该系统能够连续稳定引导太阳辐射监测仪进行跟踪测量,且满足太阳辐射监测仪在轨跟踪精度要求. 相似文献
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通过对火电厂旁路系统高压蒸汽阀门在不同开度下阀体振动信号幅值变化的实测分析 ,探讨了利用振动测量定量诊断阀门泄漏的方法 ,分析了负荷变化、测量位置等因素对阀体振动的影响。研究表明 ,通过正确选择测量位置、设定参考基准 ,可以很好建立阀门泄漏与振动幅值之间的比例关系 ,实现阀门泄漏的定量诊断。 相似文献
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针对辐射能可以反映燃料量变化的事实,利用炉膛内热平衡的方法推导出了辐射能与燃料量的关系式,可知燃料量发生量的变化后辐射能的量的变化。通过分析辐射能的检测方法,得出辐射能与辐射图像R、G、B值之间存在非线性关系,因此提出一种用BP神经网络测量辐射能的方法,并在实验室黑体炉上进行了试验。该神经网络为一个具有三输入、一输出、含有两个隐含层的BP网络。试验拍摄的辐射图像R、G、B值作为BP神经网络的三个输入值,试验得到的辐射能值作为BP神经网络的输出值,将代表输入输出的18组样本利用BP神经网络进行学习后得到了较为理想的测量辐射能的网络。试验表明该方法精度是比较高的。结合辐射能与燃料量的关系式,该试验方法可应用到实际炉膛中。 相似文献
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蓄电池组作为低轨道卫星上重要的储能设备,其工作状态直接影响到整星工作的安全性和稳定性。而合理有效的充电策略和控制手段能够有效延缓蓄电池性能的衰降速度,延长其在轨使用寿命。指出了以往充电终止控制策略的局限性,并且在分析了低轨道卫星电源系统特点的基础上,提出了一种由电源下位机软件实现的阶段性限流充电控制策略,通过周期性地监测蓄电池的电量与转阶段门限值的大小,分别在软件限流控制步骤中对充电阵进行开启关闭控制。该方法通过软件实现,其中重要参数均可实现在轨上注调整,减小了以往充电过程中充电电流受负载变化引起的电压波动影响,增强了低轨道卫星蓄电池充电控制的灵活性和安全性,整个电源系统工作更加稳定,并通过在轨试验验证了其可行性,保证了蓄电池良好的工作状态。 相似文献
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以信号处理为基础,根据谐波激励特征,结合离散傅里叶变换推导了振动主动控制中时滞测量算法的理论。在图形化开发软件LabVIEW编程实现该算法,并进行了仿真验证。为将该算法应用于实际中测量时滞,依据振动主动控制工程背景,试验研究了在振动主动控制中时滞量较大的作动器的时滞规律。为研究时滞量和输入控制电压信号参数之间关系,对作动器进行了时滞试验方案设计,得到作动器时滞量与输入电压信号的频率和幅值参数变化之间的关系图,基于试验结果进一步总结电磁式作动器的时滞变化规律。 相似文献
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《电网技术》2017,(7)
由于不良数据会导致电力系统发生错误的动作,对相量测量单元(phasor measurement unit,PMU)的相量测量精度进行在线评价对于广域监控系统至关重要。基于相量测量值变化量的波动特性,提出一种PMU测量性能在线评价方法。首先分析了相量测量值变化量的波动特性与算法性能之间的关系,然后将量化波动幅度的标准差定义为波动指数来评价测量值的精度水平,并通过相邻的相量测量值实时地计算波动指数。最后,在频率线性变化、低频振荡及噪声干扰等动态工况下,利用不同的相量测量算法,对所提方法进行测试,其结果表明:在大多数情况下波动指数与综合矢量误差(total vector error,TVE)的变化趋势保持一致。此外,该方法产生的运算量满足在线评价应用的需求。 相似文献
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The article talks about recent Defense Research Projects Agency (DARPA) presolicitation notice in the area of hybrid insect micro-electromechanical systems (MEMs). DARPA's goal is to fund promising interdisciplinary research that will permit the creation of "insect-cyborgs" 相似文献
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The emergence of quick lock connectors, particularly quick lock versions of the SMA and N connectors (QMA and QN, respectively), was an inevitable development in the RF connector industry and is of significant importance in that nearly 50% of all practical applications for RF connectors are currently supported by either SMA or N. Once QMA and QN can achieve similarity in cost and performance to the present SMA and N connectors, they will take the place of their predecessors in most applications, creating a huge new market. Our RF team has long been dedicated to research and development of these two connector types in the hopes of creating an optimal design. In this article, we will show some of the results of our research. 相似文献
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Dr.-Ing. A. K. Gąsiorski 《Electrical Engineering (Archiv fur Elektrotechnik)》1987,70(3):187-193
Contents In the paper Joule power losses are calculated in a conducting ring enclosing a conductor with a transient current having an alternating component.—Theoretical calculation and numerical computation are worked out basing on a link Bubnov-Galerkin method in its numerical version using the finite elements for the conductor with the Time-Stepping algorithm for the time discretization.—On the basis of numerical computation, graphs of the relative power losses are plotted as a time function.
List of symbols Symbol Unit Physical parameter - B Wb/m2 magnetic induction vector - H A/m magnetic field intensity vector - H, H A/m -component of the magnetic field vector - E V/m electrical field vector - E r ,E z V/m components of the electric field - f s–1 frequency - I A current intensity (r.m.s. value) - L H inductance - P W power losses - P 0 W power losses for d.c. - R resistance - t sec time - –1 m–1 electric conductivity of the conductor - Hm–1 magnetic permeability - ijk m2 finite element area - basis function - rad s–1 pulsation - N i ,N j ,N k function of finite element shape - 3.141593... - region - 2 Laplace's operator - r, ,z cylindrical coordinates - h region approximating the region - e finite element region - M number of discretization points of the region - V number of finite elements - (N–1) number of steps - i, j, k indices of vertices of triangular finite element 相似文献
Leistungsverluste in einem leitenden Ring, der einen Leiter mit einem instationären Strom umschließt
Übersicht In diesem Beitrag werden die Joulschen Leistungsverluste in einem leitenden Ring berechnet, der einen Leiter umschließt, in dem ein instationärer Strom mit Wechselanteil fließt. Die theoretischen Betrachtungen und numerischen Berechnungen hat man in Anlehnung an die Bubnov-Galerkin-Methode (in ihrer numerischen Variante, die von einen Leiter unter Verwendung der Methode der finiten Elemente realisiert wird) in Verbindung mit einem Schritt-Algorithmus mit der diskretisierten Zeit ausgeführt. Auf der Grundlage numerischer Berechnungen sind Diagramme für die relative Leistung in Abhängigkeit von der Zeit dargestellt.
List of symbols Symbol Unit Physical parameter - B Wb/m2 magnetic induction vector - H A/m magnetic field intensity vector - H, H A/m -component of the magnetic field vector - E V/m electrical field vector - E r ,E z V/m components of the electric field - f s–1 frequency - I A current intensity (r.m.s. value) - L H inductance - P W power losses - P 0 W power losses for d.c. - R resistance - t sec time - –1 m–1 electric conductivity of the conductor - Hm–1 magnetic permeability - ijk m2 finite element area - basis function - rad s–1 pulsation - N i ,N j ,N k function of finite element shape - 3.141593... - region - 2 Laplace's operator - r, ,z cylindrical coordinates - h region approximating the region - e finite element region - M number of discretization points of the region - V number of finite elements - (N–1) number of steps - i, j, k indices of vertices of triangular finite element 相似文献
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This paper proposes a nonlinear circuit that generates chaotic oscillations. The proposed nonlinear circuit includes a nonlinear capacitor and a nonlinear inductor by using Generalized Impedance Converters. Both computational experiments and experiments on real circuits show that the region for chaotic oscillation is very wide, demonstrating that the proposed circuit is effective as a chaos generator. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 35–42, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10361 相似文献
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Matsuo H. Yamashita T. Fujishima T. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2006,13(2):408-414
To develop a propagation model of a local discharge on a wet polluted insulator, the authors have examined characteristics of the local discharge on an electrolytic solution simulating the wet polluted insulator surface. The local discharge was propagated on the solution under the impulse voltage. A shape of a contacting surface between the local discharge and the solution has been already obtained by the authors. By using the contacting surface, an electric potential near a tip of the local discharge on a conductive film of 1 mm in thickness was calculated. Furthermore, the potential was measured with a probe. The calculated values and the measured values of the electric potential agreed well regardless of the propagation length of the local discharge, the width of the conductive film, the resistivity of the conductive film, the peak value of the applied voltage and the applied voltage waveform. 相似文献
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Diaz J. Martin-Ramos J.A. Prieto M.J. Fernandez Linera F.M. Nuno F. 《Industry Applications, IEEE Transactions on》2002,38(5):1226-1231
The development of an automatic deceleration system for a winding machine in a siderurgy factory is presented in this paper. The proposed system controls the speed of a winding machine in order to obtain the optimum stop point in terms of security and fast production. The system is based on a microcontroller and an extremely simple hardware. The system has been tested for two years and results evince a very good mean time between failures. 相似文献
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I. M. Kirpichnikova A. S. Mart’yanov E. V. Solomin 《Russian Electrical Engineering》2013,84(10):577-580
Analysis of excitation systems of generators for wind-power units is carried out, a software package for generator simulation is presented, and the sequence of the generator design is presented. 相似文献
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The neural network approach is reviewed in the context of studies in the animal and human visual systems. An attempt is made to explain perception, memory, and learning as a feedback loop similar to the one used in the ALOPEX optimization concept. Applications in pattern recognition and image processing are discussed. Experiments using visual evoked potentials in humans are described. 相似文献