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991.
连云港口门防波堤建设对航道回淤影响数值研究 总被引:2,自引:0,他引:2
以连云港海区为例,建立潮流、波浪共同作用下的泥沙运动数学模型,应用年平均含沙量场作为依据对临界冲刷切应力和冲刷率进行率定,并利用实测资料对模型进行验证。在模型基础上研究了口门防波堤建设对年平均含沙量场及进港航道回淤的影响,分析了工程后平均含沙量场的分布形式和航道回淤强度的沿程变化规律。结果表明防波堤修建后,口门处含沙量较高,并向港内和外海逐渐降低,航道回淤强度分布形态与航槽内含沙量分布形态相似;航槽第二年回淤率低于第一年。 相似文献
992.
Jun-Sik Kim Myung Hwangbo Takeo Kanade 《Computer Vision and Image Understanding》2010,114(10):1068-1083
Estimating motions of a multi-camera system which may not have overlapping fields of view is generally complex and computationally expensive because of the non-zero offset between each camera’s center. It is conceivable that if we can assume that multiple cameras share a single optical center, and thus can be modeled as a spherical imaging system, motion estimation and calibration of this system would become simpler and more efficient. 相似文献
993.
994.
U. S. Pathre M. R. Driels 《The International Journal of Advanced Manufacturing Technology》1990,5(1):13-33
This paper examines the factors to be considered for the identification of kinematic parameters during robot calibration.
A generalised calibration experiment has been simulated using two different identification techniques. Details of the identitication
techniques and considerations for implementing them using standard IMSL routines are presented. The factors considered during
the simulations include initial estimates of parameters, effect of measurement noise, number of pose measurements, and accuracy
of the measurement system used. Results are tabulated for the various cases and suggestions are made towards the efficient
planning and execution of robot-calibration experiments. 相似文献
995.
《中国科学E辑(英文版)》2005,(Z2)
Presently China has developed and launched more than 30 earth observing satellites. The primary series of FY, HY and resource satellites have been constructed. In China, earth observing techniques have been developed rapidly and the achievements are re- markable, but compared with the developed countries, there is still a long way to go. Besides, the quantitative application research of satellites data in China is not profound enough. Thus, it is urgent to consider how to systematically con… 相似文献
996.
Barry A. Bell 《Journal of research of the National Institute of Standards and Technology》1990,95(4):377-405
Over the last decade the use of digital synthesis and sampling techniques for generating and measuring electrical waveforms has increased dramatically with the availability of improved digital-to-analog (D/A) and analog-to-digital (A/D) converters and related devices. With this evolution has come the need for physical laboratory standards and test methods to support the performance specifications of digital devices and the instruments in which they are used. This article describes the research and development at NIST of several laboratory standards and test systems that utilize “digital technology” for characterizing data converters and for implementing various waveform synthesis and sampling instruments. 相似文献
997.
K. D. Cliff 《Journal of research of the National Institute of Standards and Technology》1990,95(2):135-138
A procedure for the calibration of instruments for the detection of 222Rn in air is described. The method is based on the alpha-spectrometric determination of the concentration in air of 218Po in the calibration chamber. The calibration chamber is described, together with the method of maintaining a high aerosol concentration. The 218Po concentration at steady state in the chamber is found to be 98% of the 222Rn concentration typically. An assessment of the sources of uncertainty in the method presented indicate that the 222Rn concentration in the chamber can be determined with an overall uncertainty of about 7% at the 95% confidence level. 相似文献
998.
Applications in automated microscopy and three-dimensional microscopy require careful calibration of the microscope system. This paper presents methods for calibration of the motorized z -axis (focus or optical axis) of an automated microscope. Apart from the automated microscope the procedures require a CCD camera and a test slide containing a simple bar pattern. The calibration embraces the following characteristics of the z -axis: (a) measuring the motor step size in nanometres; (b) measuring the mechani-cal backlash in the focus mechanism of the microscope and (c) measuring the reproducibility and the stability of the focus position over time. The measurements employ focus functions to determine the z -position of the microscope stage. 相似文献
999.
1000.