共查询到19条相似文献，搜索用时 406 毫秒
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磁性材料的磁特性参数的测量已成为信息化程度的重要标志,本文主要介绍了数字式冲击检流计测量静态磁性参数的原理,并且分析了在测量过程中存在的误差。 相似文献
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采用三种方法对灵敏电流计的特性参数进行测量,并对测量结果进行了误差分析和比较,给出了测量人体皮肤电流时,选取仪器参数的方法. 相似文献
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井深是现场录井项目中非常重要的测量参数,它是一切录井工作的基础。只有录井深度测量准确无误,才能保证与之相对应的其他录井测量参数具有解释评价价值。本文通过对现场录井过程中井深测量系统进行分析,找出影响井深测量的因素,采取对应的措施来提高井深测量的准确性。 相似文献
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在使用通用的阻抗计法测量石英晶体谐振器的谐振频率和其它电参数时,晶体接入测量线路时产生的分布参数严重影响其测量精度．分析这些影响产生的原因并据此改进测量方法和采取适当的补偿措施,可以显著提高测量精度 相似文献
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对已研制的转向参数测量装置在测试中产生的偶然误差进行分析,指出误差产生原因,对现有的测量装置进行改进。计量检测结果表明：应用改进后的转向参数测量装置能消除测试误差,使测量装置完全满足设计和使用要求。 相似文献
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实时动态GPS测量技术广泛地应用于测绘领域。在实际坐标系统间的转换应用中,求解出的转换参数的精度高低将直接影响测量成果。因此,转换参数的求解在实际测量应用中有着重要的意义。 相似文献
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对接触式测头的测量原理进行分析,将影响接触式测头动态精度参数归结为7个主要测量参数：逼近速度,测量力,测杆长度,逼近距离,测头方向,采点数,测端直径。同时分析了这些参数与主要误差之间的关系,提出在实际动态测量状态下测量参数是影响测头精度的重要因素。以GLOBAL9158型三坐标测量机为实验对象,改变相关参数值对标准球进行测量并做出误差分析。结果显示各参数变化均会带来测量误差,而逼近速度是影响接触式测头动态精度的最主要影响因素,其最大测量误差达到3．3um超过测量机最大允许探测误差2．7um,并且会导致测头十分明显的探测不稳定性。 相似文献
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远距离弱小目标视觉测量系统探测能力模型研究 总被引：1，自引：0，他引：1
在远距离视觉测量过程中,视觉测量系统参数选择不当,将无法使被测目标成像,从而严重影响视觉测量系统的探测能力。根据远距离弱小目标的成像特点,研究了弱小目标成像与目标光照度、成像距离、传感器灵敏度、动态范围、曝光时间及光学系统光孔大小等参数的关系,建立了远距离弱小目标视觉测量系统的极限探测距离模型,为远距离弱小目标视觉测量系统的参数选型提供了理论依据。为了验证成像系统极限作用距离模型在具体应用中的有效性,对具体的视觉测量系统进行了探测能力试验。试验表明:测量值与计算值基本一致,特别是两者的变化趋势一致,证明该模型基本正确,可用于视觉测量系统的探测能力估计。 相似文献
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D. Wulich 《Journal of The Franklin Institute》1984,317(3):135-145
A novel method of noise variance measurement in the presence of strong sine burst interference with unknown parameters is presented. The measurement system is based on the Adaptive Sine Pulse Shortener (ASPS) which shorts each sine pulse from which the interfering burst is composed. After this a conventional noise variance measurement method is applied. A measurement accuracy is satisfactory when the interfering signal is strong and the number of periods of interfering sine-wave in each sine pulse is great. While a practical implementation of the proposed procedure is not simple in hardware, the microprocessor implementation is quite realizable. 相似文献
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适用复杂流场五孔探针的研制与校准 总被引：1，自引：0，他引：1
采用分段拟合并对不同参数阶次进行优化建立了五孔探针数学模型,在利用非对向自动测量方法的基础上研发了一套计算机数据实时采集和处理程序,结果表明该数学模型具有很高的数值精度,该程序提高了测试速度,保证测试精度,满足了复杂流场的测试要求。 相似文献
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Hamdi Echeikh Ramzi Trabelsi Atif Iqbal Med Faouzi Mimouni 《Journal of The Franklin Institute》2018,355(5):2112-2141
High performance multiphase motor drive requires precise knowledge of the state quantities and the machine parameters. Access to these state quantities is through measurement using sensors whose accuracy is paramount to achieve the performance level required by industrial applications. However, the problems of the parameters variations, inaccessibility to the measurement of some states, no-observability of the machine in some regions, the cost of the sensors and their lack of precision, make this very difficult task. To address these problems, it is necessary to resort to soft sensors through the design of observers and estimators. In multiphase induction motor drive, the observation problem arises especially for rotor flux that is not accessible for measurement. About the parameters variations, the rotor resistance and the stator resistance are the most critical parameters of the machine because their influence is crucial for the control and observation. The change in the resistances can be as large as 40–50% of the rated value, which may affect the control adversely. This paper develops a new structure of an adaptive sliding mode observer based on an online estimation of the rotor resistance value in order to avoid the effect of its variation in the rotor flux oriented control. The results show convergent (the errors in the transient and steady states are 5% and 1%, respectively) behavior of the drive using the proposed control scheme for large rotor resistance variation under loaded condition. The stability of the drive is proved using Lyapunov criteria. The simulation results are validated using real time implementation. 相似文献
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Cheng-Hung Huang 《Journal of The Franklin Institute》2005,342(7):793-813
The conjugate gradient method (CGM), or the iterative regularization method, is applied to a generalized inverse nonlinear force vibration problem, (i.e. system parameters are function of displacement), to simultaneously estimate the unknown time-dependent external forces for a multiple-degree-of-freedom damped system by using the measured displacements. The system parameters of the present study are considered function of displacement, thus it is classified as a genuine nonlinear inverse vibration problem. The numerical experiments are performed to test the validity of CGM by using different types of system parameters, external forces and measurement errors in this study. 相似文献
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Giuseppe Fedele 《Journal of The Franklin Institute》2009,346(1):1-9
In this paper an identification method to estimate the parameters of a first-order plus time delay model is proposed. Such a method directly obtains these parameters using a new linear regression equation. No iterations in calculation are needed. Moreover, a simple true/false criterion to establish if the hypothesis on the process type is correct can be easily derived. The proposed method shows an acceptable robustness to disturbances and measurement noise as it is confirmed by several simulated experiments. 相似文献
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中美大学网络影响因子研究 总被引：6，自引：0，他引：6
选取了中国和美国26所大学,对其进行了网络影响因子测定,考察了其中6项指标。结果表明：（1）网络影响因子各项指标中,美国大学均高于中国大学,两者在网页总数和链接总数方面存在巨大的差异,而其链接效率则较为相近;（2）单一的网络影响因子项指标无法完全表征大学网站的影响力,但是充分利用各种数据的关联性进行综合性评价则可以做出接近事实的结论;（3）外部网络影响因子由于与链接效率存在线性正相关性,所以能够更客观地评价大学网站的影响力。 相似文献
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《Journal of The Franklin Institute》2023,360(2):1124-1144
In this paper, the output feedback tracking control problem is investigated for polynomial nonlinear systems (PNSs) with measurement noises and mismatched disturbances. First, in order to suppress measurement noises, a polynomial observer is introduced to simultaneously estimate states and mismatched disturbances. Next, based on the idea of backstepping control, a novel output feedback controller is designed for PNSs to compensate mismatched disturbances. Command filters are employed to avoid the repeated derivatives of virtual control and measurement noises in the recursive controller design. Then, a sufficient condition in terms of the parameter-dependent linear matrix inequality (PDLMI) is derived to guarantee the boundedness of tracking errors and estimation errors. By utilizing the sum of squares (SOS) decomposition technique, the PDLMI is solved to obtain desired controller parameters. Finally, an example of dynamic point-the-bit rotary steerable drilling tool system is performed to demonstrate the effectiveness and feasibility of the proposed strategy. 相似文献
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《Journal of The Franklin Institute》2022,359(11):5682-5711
This work presents an iterative concept of the State-space Realization Algorithm with Data Correlation (SSRA-DC) to identify MIMO systems with measurement noise and subjected to a reduced number of samples acquired from the process. The measurement noise is characterized as a random signal with properties of white noise and having up to 1% of the output signal amplitude. The proposed technique is based on the Markov parameters matrix’s feedback in an iterative algorithm supported by the SSRA-DC method. A gain factor takes part in the closed-loop to update the Markov parameters matrix, reducing their residues at each iteration. A fixed value for the gain is applied all over the iterations. The Gaussian White Noise (GWN) is employed as the input excitation signal in simulated experiments of mass-damper-springer models with 50 and 100 degrees of freedom. For some algorithm settings, one hundred simulations, each holding more than 100 iterations, are performed to statistically demonstrate the iterative algorithm’s effectiveness compared to the conventional SSRA-DC. Further comparative analysis is accomplished between the iterative method with the ARMAX and N4SID algorithms. 相似文献