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单元分解方法是近年来得到广泛发展和应用的无网格方法的一个重要分支。相对于其它无网格方法,它具有更大的灵活性和高精度。本文对现有的单元分解方法进行了综述。阐述了它与其它无网格方法的关系,讨论了单元分解方法的优点和不足。文中还给出了单元分解方法的一般公式及其推导,介绍了用流形方法实现单元分解方法的数值计算,并给出了单元分解方法的算例。最后,介绍了单元分解方法的最新发展状况,并展望了它的发展方向和前景。 相似文献
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针对机器人视觉伺服系统的特点,对适用的图像处理和标定方法做了研究和总结.首先对图像处理的过程和主要方法进行了归纳,然后着重对系统标定的方法进行了阐述,并对典型的标定算法进行了分类和比较,最后对图像处理和标定方法进行了展望和总结. 相似文献
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本体集成方法评价指标体系及其应用研究 总被引:7,自引:0,他引:7
通过本体关联方法和层次的分析,提出了本体映射、本体结盟和本体合并3种本体集成分类方法。建立了本体集成方法的评价指标体系,包括方法的语义强度、信息的丰富性、集成层次的深入性和方法的适应性4个方面,并在评价指标的基础上,对文法层,Chimaera,PROMPT,FCA-Merge和IF-Map等5种典型的本体集成方法进行了评价,对比分析了它们的优缺点,并以此为基础指出了本体集成方法的发展趋势。 相似文献
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机电装备失效研究的内涵及其科学问题探讨 总被引:3,自引:2,他引:3
简要介绍了失效研究领域的相关名词、概念和内容。对失效对象、失效现象和失效环境等与失效有关的5大类、16项、共52种失效信息进行了归纳总结,并指出了通过这些信息来建立诊断失效模式、原因和机理的失效诊断系统的途径。针对失效研究领域中,失效诊断方面存在的断口、裂纹诊断技术和方法,综合诊断技术和方法,定量诊断技术和方法,概率诊断、模糊诊断和智能诊断的技术和方法,环境诊断技术和方法,失效抗力(材料性能)指标体系和表征技术,失效动力(载荷或应力)的计算、测试和反推技术和方法,失效模拟的技术和方法,失效预测方面存在的技术和方法,以及失效预防方面存在的技术和方法等10大类科学问题,从理论和实践两方面进行了探讨,并指出了需要进一步研究的方向。最后指出了该领域今后的发展趋势。 相似文献
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介绍了振动打桩机的原理、打桩方法的分类和各种打桩方法的特点,分析了应用振动打桩机进行钢板桩施工的方法,包括技术要求和具体步骤,并给出了钢板桩施工中常见的问题和处理方法。 相似文献
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孙杰 《仪器仪表标准化与计量》2021,(1):22-24
本文介绍了移动通信网络数据流量测量方法现状并分析了缺点,提出了一种新的移动通信网络数据流量测量方法,并就方法基本原理和计费数据流量定义进行详细论述,给出了实验方法和实验数据,验证了方法的准确性和可靠性. 相似文献
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《Measurement》2014
The moving least squares (MLS) method and the moving total least squares (MTLS) method have been developed to deal with the measured data contaminated with random error. The local approximants of MLS method only take into account the error of dependent variable, whereas MTLS method considers the errors of all the variables, which determines the local approximants in the sense of the total least squares. MTLS method is more reasonable than MLS method for dealing with errors-in-variables (EIV) model. But because of the weight function with compact support, it is complicated to choose fitting method for the best performance. This paper presents an Adaptive Moving Total Least Squares (AMTLS) method for EIV model. In AMTLS method, a parameter λ associated with the direction of local approximants is introduced. MLS method and MTLS method can be considered as special cases of AMTLS method. Curve fitting examples are given to prove the better performance of AMTLS method than MLS method and MTLS method. 相似文献
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针对传统模拟车轮踏面制动摩擦热流边界的加载方式存在的不足,如均布热源法计算精度较低和移动热源法计算效率较低,提出基于间隙热流加载法的车轮踏面制动摩擦温升有限元计算方法。以重载列车紧急制动为研究对象,通过与以往的移动热源法和均布热源法进行对比,研究新方法的计算精度和计算效率。计算结果显示:在计算精度方面,新方法不仅可以达到移动热源法的计算精度,还能体现均布热源法无法模拟的因闸瓦和踏面的接触-脱离现象导致的车轮踏面温度时间历程曲线波动现象。在计算时间方面,新方法的计算效率与均布热源法的相当,但新方法的计算速度比移动热源法的快4.3倍。 相似文献
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主要介绍了无刷直流电动机采用的反电动势过零点检测法。提出了用端电压法、相电压法两种反电动势过零点检测法检测电机转子位置,并对端电压法和相电压法做了进一步的说明。 相似文献
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在大型复杂的结构设计过程中,子结构综合与修正方法由于其快速、动态、综合等特点越来越广泛地应用于现代结构设计之中,以完善子结构综合与修正方法知识参考、引起国内学者关注该技术研究为目的,阐述了振动子结构与系统之间的综合与修正方法。在子结构综合方法中,主要对比分析了模态缩减与综合、频域JETMUNDSEN、REN、机械阻抗导纳法综合法、频响函数奇异值分解降噪法、子系统转角自由度刚柔等效及转换方法的原理及应用,评述了上述方法的优点与不足,就尚未解决的问题作了进一步探讨;在子结构修正方法中,对比分析了多重参考基准修正法、目标函数动态修正法、参数型修正、神经网络型修正、灵敏度修正、频响函数修正等方法的应用,总结了模型修正方法中存在的一些问题。最后,提出了振动子结构综合及修正方法的研究趋势。 相似文献
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Advanced median method for timing jitter compensation 总被引:1,自引:0,他引:1
Wang Chen Zhu Jiangmiao Jan Verspecht Liu Mingliang Li Yang 《仪器仪表学报》2008,29(3):472-476
Timing jitter is one of the main factors that influence on the accuracy of time domain precision measurement. Timing jitter compensation is one of the problems people concern. Because of the flaws of median method, PDF deconvolution method and synthetic method, we put forward a new method for timing jitter compensation, which is called advanced median method. The theory of the advanced median method based on probability and statistics is analyzed, and the process of the advanced median method is summarized in this paper. Simulation and experiment show that compared with other methods, the new method could compensate timing jitter effectively. 相似文献
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Energy based signal parameter estimation method and a comparative study of different frequency estimators 总被引:1,自引:0,他引:1
The influences of window functions and noise on the performance of the energy-based signal parameter estimation method are investigated, and the appropriate parameters and algorithm are recommended accordingly. The frequency, amplitude and phase estimation variances of the energy based method are deduced and verified by computer simulation. The performances of four frequency estimation methods are compared: the energy based method, the interpolation based method, the phase difference based method and the Fourier transform (FT) continuous zoom based method. For the second and third methods, the Quinn algorithm and the phase difference based method with factor η=0.5 are recommended, respectively. It was found that each method has its own advantages. The energy based method has the best stability compared with others. The interpolated method has the lowest frequency estimation variance when the frequency biasδ is large, while the phase-difference based method does better when δ is low. The change of δ does not influence the maximum frequency estimation error of the FT continuous zoom based method. Comparatively speaking, the phase-difference based method has the least frequency estimation error. 相似文献
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The reason for the rounding error in a measurement system under the condition of a limited sampling period is analysed, and a three-point method based on the difference algorithm (D3P method) is proposed. The effect of the rounding error is reduced by differential approximation of the roundness error and reconstruction of the transfer function. The generalized three-point method (G3P method), the three-point method based on the first-order difference algorithm (I-D3P method) and the three-point method based on the second-order difference algorithm (II-D3P method) are compared and analysed by simulation. The results show that the accuracy of the D3P method is greatly improved compared with that of the G3P method under the restricted sampling period and that the D3P method retains high precision in the case of failed error separation of the G3P method. An experimental system was constructed to realize error separation, and the experimental results show that the D3P method has higher accuracy than the G3P method over a small sampling period. 相似文献