共查询到20条相似文献,搜索用时 0 毫秒
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T. NiewierowiczAuthor Vitae E. Campero-LittlewoodAuthor Vitae 《Computers & Electrical Engineering》2003,29(4):505-522
A hybrid genetic algorithm is used to find high-order equivalent circuits (ECs) of synchronous machines using standstill frequency response (SSFR) data. The algorithm performs satisfactorily despite the great deal of local minima surrounding the optimal solution of high-order ECs. It gives circuit parameters that simultaneously fit the three independent transfer functions given by the d-axis two-port network of the synchronous machine. It is found that as the order of the EC is increased, the optimization index used in the identification procedure is enhanced in a clear fashion. This leads to a new way for determining the right number of rotor branches required to correctly reproduce the SSFR data. The q-axis network is also analyzed with the hybrid algorithm. The so-called Canay's inductances are included in this one-port network to test if the fitting properties of the q-axis EC can be improved. The SSFR data used in this work is generated by a finite element model of a turbine generator, but actual data can also be readily handled. 相似文献
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A novel computer system tool for the parameter estimation of mathematical synchronous-machine models is presented. It uses state-of-the-art information technology software. The tool allows the electrical power engineers to obtain the electrical parameters of a synchronous machine model. The practical usefulness of the developed system is demonstrated by obtaining the parameter set for conventional and high order d and q axis models from the dc flux decay test. The two-axis model parameters are estimated with the well-known maximum likelihood algorithm. The user can also validate its set of estimated parameters against experimental data. Consequently, a better behavior prediction of synchronous generators within a power system can be achieved. The tool was developed using LabVIEW as a software environment and a low cost data acquisition card, which has a user friendly interface. A solid salient-pole synchronous generator of 7 kVA was used to illustrate its practical impact of the proposed system, where acceptable accuracy in the set of estimated parameters was achieved. 相似文献
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In this paper,an adaptive control scheme is introduced for permanent magnet synchronous machines (PMSMs)as an alternative to classical control techniques.The adaptive control strategy capitalizes on the machine’s inverse dynamics to achieve accurate tracking by using an observer to approximate disturbance in the form of friction and load torque.The controller’s output is then fed to a space vector pulse width modulation(SVPWM)algorithm to produce duty cycles for the inverter.The control scheme is validated through a set of simulations on an experimentally validated PMSM model.Results for different situations highlight its high speed tracking accuracy and high performance in compensating for friction and load disturbances of various magnitudes. 相似文献
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S.Yu. Lukashchuk 《Computers & Mathematics with Applications》2011,62(3):834-844
This paper presents an extension to the time integral characteristics method for estimation of parameters in fractional subdiffusion equations containing Riemann-Liouville and Caputo fractional time derivatives. The explicit representations of the fractional diffusion coefficient and order of fractional differentiation via a Laplace transform of the concentration field are obtained. A technique of optimal Laplace parameter determination by minimization of relative errors bounds is described. The effectivity of the proposed approach is illustrated by numerical example. 相似文献
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This paper investigates a machine repair problem with homogeneous machines and standbys available, in which multiple technicians are responsible for supervising these machines and operate a (R, V, K) synchronous vacation policy. With such a policy, if any V idle technicians exist in the system, these V (V < R) technicians would take a synchronous vacation. Upon returning from vacation, they would take another vacation if there is no broken machine waiting in the queue. This pattern continues until at least one failed machine arrives. It is assumed that the number of teams/groups on vacation is less than or equal to K (0 ≦ KV < R). The matrix analytical method is employed to obtain a steady-state probability and the closed-form expression of the system performance measures. Efficient approaches are performed to deal with the optimization problem of the discrete/continuous variables while maintaining the system availability at a specified acceptable level. 相似文献
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根据序贯实验设计原理,提出用于 B_(110-2)催化剂的动力学模型参数估值程序,并提出B_(110-2)催化剂的中温变换反应本征动力学方程。 相似文献
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采用相关向量机从含噪时间序列中估计小世界神经元网络的节点动力学方程和拓扑结构。在具有多项式结构或能以幂级数展开的动力学系统中,将未知方程写成统一多项式形式,原动力学方程的项在统一多项式中是稀疏的,利用稀疏贝叶斯学习估计出稀疏项从而实现动力学方程和拓扑结构的估计。利用该方法对FHN小世界神经元网络进行节点动力学方程和拓扑估计,结果表明,该方法能快速准确地估计节点动力学方程结构和网络拓扑,对动力学方程系数和网络耦合强度有很高的估计精度,而且对噪声有强鲁棒性。 相似文献
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离散HMM的参数估计 总被引:1,自引:0,他引:1
给出了两种离散HMM参数估计,一种是首先估计HMM的转移概率和直接估计离散符号集的分布,然后假设各状态都是正态分布,再从符号集的离散概率分布,来估计正态概率分布的参数(GMM);另一种是将离散符号设定为正态分布,用与连续HMM相似的方法,来估计离散HMM正态概率分布的参数。 相似文献
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Felipe M. Pait 《Systems & Control Letters》1998,35(1):381
We propose a tuner, suitable for adaptive control and (in its discrete-time version) adaptive filtering applications, that sets the second derivative of the parameter estimates rather than the first derivative as is done in the overwhelming majority of the literature. 相似文献
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基于参数估计的多传感器数据融合 总被引:22,自引:1,他引:21
探讨具有随机扰动的环境中同一特征的不同传感器测量值的融合问题,并在理论上给出了基于参数估计的多传感器融合算法,分析了正态分布数据的融合计算公式,并提出以数据探讨技术中的分布图方法来获得一致的传感器数据,从而提高了算法的鲁棒性。 相似文献
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介绍了PC机平台上汽车动态称重系统,主要使用数字滤波方法滤除干扰,对滤波后波形调整后使用参数估计算法进行信号处理,准确的提取出静态轴重信号。实测数据的处理结果证明了方法的有效性。 相似文献
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两相流流速测量的参数估计法研究 总被引:2,自引:0,他引:2
为了解决相关法流速测量分辨率较低、实时性较差的问题,介绍利用极性导向式自适应算法测量两相流流速的参数估计新方法。文中详细论述实现这种算法的硬件电路结构及其工作过程,并给出气水两相流垂直管段与极性相关法进行对比实验的结果。新仪器测量结果的分辨率和实时性优于相关法。 相似文献
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Tahar Hamiti Thierry Lubin Lotfi Baghli Abderrezak Rezzoug 《Mathematics and computers in simulation》2010,81(2):354-366
The paper deals with modeling of synchronous reluctance motor (SynRM) accounting for all phenomena responsible for torque ripple. Based on winding function approach, the proposed model consists in computing self and mutual inductances considering no sinusoidal distribution of stator windings, slotting effect and no sinusoidal reluctance variation caused by the rotor saliency. Then, optimal current waveforms are determined for each rotor position by solving a second order equation to reduce torque ripple. These currents are used within a vector control scheme. Satisfactory agreement between simulation and experimental results is obtained. 相似文献
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针对目前机器翻译模型存在的曝光偏差和译文多样性差的问题,提出一种基于强化学习和机器翻译质量评估的中朝神经机器翻译模型QR-Transformer.首先,在句子级别引入评价机制来指导模型预测不完全收敛于参考译文;其次,采用强化学习方法作为指导策略,实现模型在句子级别优化目标序列;最后,在训练过程中融入单语语料并进行多粒度数据预处理以缓解数据稀疏问题.实验表明,QR-Transformer有效提升了中朝神经机器翻译性能,与Transformer相比,中—朝语向BLEU值提升了5.39,QE分数降低了5.16,朝—中语向BLEU值提升了2.73,QE分数下降了2.82. 相似文献
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In this paper, we propose a global method for estimating the motion of a camera which films a static scene. Our approach is
direct, fast and robust, and deals with adjacent frames of a sequence. It is based on a quadratic approximation of the deformation
between two images, in the case of a scene with constant depth in the camera coordinate system. This condition is very restrictive
but we show that, provided translation and depth inverse variations are small enough, the error on optical flow involved by
the approximation of depths by a constant is small. In this context, we propose a new model of camera motion which allows
to separate the image deformation in a similarity and a “purely” projective application, due to change of optical axis direction.
This model leads to a quadratic approximation of image deformation that we estimate with an M-estimator; we can immediately
deduce camera motion parameters.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users.
相似文献
G. KoepflerEmail: |
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The effect of the Bidirectional Reflectance Distribution Function (BRDF) is one of the most important factors in correcting the reflectance obtained from remotely sensed data. Estimation of BRDF model parameters can be deteriorated by various factors; contamination of the observations by undetected subresolution clouds or snow patches, inconsistent atmospheric correction in multiangular time series due to uncertainties in the atmospheric parameters, slight variations of the surface condition during a period of observation, for example due to soil moisture changes, diurnal effects on vegetation structure, and geolocation errors [Lucht and Roujean, 2000]. In the present paper, parameter estimation robustness is examined using Bidirectional Reflectance Factor (BRF) data measured for paddy fields in Japan. We compare both the M-estimator and the least median of squares (LMedS) methods for robust parameter estimation to the ordinary least squares method (LSM). In experiments, simulated data that were produced by adding noises to the data measured on the ground surface were used. Experimental results demonstrate that if a robust estimation is sought, the LMedS method can be adopted for the robust estimation of a BRDF model parameter. 相似文献