期刊文献+
共找到9篇文章
< 1 >
每页显示 20 50 100
数字图像处理技术在干涉仪中的应用 被引量:1
1
作者 祝彦 丁振君 +1 位作者 王芳 贾克军 《河北大学学报(自然科学版)》 CAS 北大核心 2012年第2期203-206,共4页
利用CCD(charge-coupled device)对立式接触式干涉仪进行改装研制,变目视观察与判读读数为光电探测、自动瞄准、测量,把显微镜下的干涉条纹图像利用CCD采集后传输到计算机.结合数字图像处理技术,利用波长定度方法实现自动定度,双边直线... 利用CCD(charge-coupled device)对立式接触式干涉仪进行改装研制,变目视观察与判读读数为光电探测、自动瞄准、测量,把显微镜下的干涉条纹图像利用CCD采集后传输到计算机.结合数字图像处理技术,利用波长定度方法实现自动定度,双边直线拟合法自动确定0级干涉条纹中心的准确位置,并根据量块形成的0级干涉条纹中心偏移像素值计算量块长度.实验测试结果表明利用数字图像处理技术消除了人为判读差错的可能性,提高了工作效率,稳定可靠. 展开更多
关键词 图像处理 CCD 自动定度 接触式干涉仪
下载PDF
Automatically positioning microseismic sources in mining by the stereo tomographic method using full wavefields 被引量:3
2
作者 缪华祥 姜福兴 +3 位作者 宋雪娟 宋建勇 杨淑华 焦俊如 《Applied Geophysics》 SCIE CSCD 2012年第2期168-176,234,235,共11页
For microseisimic monitoring it is difficult to determine wave modes and their propagation velocity. In this paper, we propose a new method for automatically inverting in real time the source characteristics of micros... For microseisimic monitoring it is difficult to determine wave modes and their propagation velocity. In this paper, we propose a new method for automatically inverting in real time the source characteristics of microseismic events in mine engineering without wave mode identification and velocities. Based on the wave equation in a spherical coordinate system, we derive a tomographic imaging equation and formulate a scanning parameter selection criterion by which the microseisimic event maximum energy and corresponding parameters can be determined. By determining the maximum energy positions inside a given risk district, we can indentify microseismic events inside or outside the risk districts. The synthetic and field examples demonstrate that the proposed tomographic imaging method can automatically position microseismic events by only knowing the risk district dimensions and range of velocities without identifying the wavefield modes and accurate velocities. Therefore, the new method utilizes the full wavefields to automatically monitor microseismic events. 展开更多
关键词 microseismic full wavefields wavefield mode identification tomographic image source parameters automatic positioning
下载PDF
Traffic Flow States in a Freeway with Bottleneck 被引量:2
3
作者 PENG Zi-Hui SUN Gang ZHU Jing-Yi 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第1期145-148,共4页
The system of mixture of single lane and double lane is studied by a cellular automata model, which is developed by us based on the Nagel and Schreckenberg's models. We justify that the model can reach a stable state... The system of mixture of single lane and double lane is studied by a cellular automata model, which is developed by us based on the Nagel and Schreckenberg's models. We justify that the model can reach a stable states quickly. The density distributions of the stable state is presented for several cases, which illustrate the manner of the congestion. The relationship between the outflow rate and the total number of vehicles and that between the outflow rate and the density just before the bottleneck are both given. Comparing with the relationship that occurring in the granular flow, we conclude that the transition from the free traffic flow to the congested traffic flow can also be attributed to the abrupt variation through unstable flow state, which can naturally explain the discontinuities and the complex time variation behavior observed in the traffic flow experiments. 展开更多
关键词 granular flow phase transition stochastic process
下载PDF
Study of the Positioning Influence in the Water Activity Measurement during Leak Test of Iodine-125 Seeds
4
作者 Joao A. Moura Anselmo Feher +6 位作者 Carlos A. Zeituni Maria E. C. M. Rostelato Wilson A. P. Calvo Oswaldo L.Costa Carla D. Souza Dib K. Junior Anderson R. Camargo 《Journal of Physical Science and Application》 2015年第5期345-348,共4页
In the prostate cancer treatment, brachytherapy with iodine-125 seeds has been used. lodine-125 seeds are sealed radioactive sources, made by a titanium capsule containing the radioisotope inside. In the final phase o... In the prostate cancer treatment, brachytherapy with iodine-125 seeds has been used. lodine-125 seeds are sealed radioactive sources, made by a titanium capsule containing the radioisotope inside. In the final phase of the seeds production, it is necessary to ensure that there is no leakage of the radioactive material. A leakage test is performed, immersing the seeds in water during 24 h and measuring the resulting activity in the water. This measurement is made in a sodium iodide detector. The immersion water is transferred to a plastic tube with a cap. The tube is placed by an automated positioning system, in the detector chamber. This study aims to determine the best positioning of the tube for the detection. It is also important to determine the influence of the positioning variation intrinsic of the automated positioning system during the iodine-125 seeds production. The results obtained will be used as a reference to adjust the equipment and process control system, in the production of the iodine-125 seeds. 展开更多
关键词 Iodine-125 seeds BRACHYTHERAPY prostate cancer treatment leakage immersion test automated positioning system.
下载PDF
A Sliding Mode Control for Uncertain Time-delay Systems
5
作者 吴军生 翁正新 +1 位作者 田作华 施颂椒 《Journal of Donghua University(English Edition)》 EI CAS 2008年第3期297-303,共7页
By means of the feasibility of some linear matrix inequalities(LMIs),delay dependent sufficient condition is derived for the existence of a linear sliding surface,which guarantees quadratic stability of the reduced-or... By means of the feasibility of some linear matrix inequalities(LMIs),delay dependent sufficient condition is derived for the existence of a linear sliding surface,which guarantees quadratic stability of the reduced-order equivalent system restricted to the sliding surface.And a reaching motion controller is proposed.A numerical simulation shows the effectiveness of the approach. 展开更多
关键词 sliding mode control time varying state-delay UNCERTAINTY linear matrix inequality (LMI)
下载PDF
Uncertainty Calculation of Roundness Assessment by Automatic Differentiation in Coordinate Metrology
6
作者 林家春 Michael Krystek 石照耀 《Journal of Measurement Science and Instrumentation》 CAS 2010年第3期224-227,共4页
Reomtly, Coordinate bieasuring Machines (CMMs) are widely used to measure roundness errors. Roundness is calculated from a large number of points collected from the profiles of the parts. According to the Guide to t... Reomtly, Coordinate bieasuring Machines (CMMs) are widely used to measure roundness errors. Roundness is calculated from a large number of points collected from the profiles of the parts. According to the Guide to the Expression of Uncertainty in Measta- meat (GUM), all measurement results must have a stated uncertainty associated the titan. However, no CMMs give the uncertainty value of the roundness, because no suitable measrement uncertainty calculation procedure exists. In the case of roundness raeasurement in coordinate metrology, this paper suggests the algorithms for the calculation of the measurement uncertainty of the roudness deviation based on the two mainly used association criteria, LSC and MZC. The calculation of the sensitivity coefficients for the uncertainty calculatiion can be done by autnatic differentiation, in order to avoid introducing additional emars by the traditional difference quotient approxima- tions. The proposed methods are exact and need input data only as the nrasured coordinates of the data points and their associated un- certainties. 展开更多
关键词 raeasurement uncertainty ROUNDNESS automatic diferentiation
下载PDF
Enhancing pose accuracy of space robot by improved differential evolution
7
作者 刘宇 倪风雷 +1 位作者 刘宏 徐文福 《Journal of Central South University》 SCIE EI CAS 2012年第4期933-943,共11页
Due to the intense vibration durirLg launching and rigorous orbital temperature environment, the kinematic parameters of space robot may be largely deviated from their nominal parameters. The disparity will cause the ... Due to the intense vibration durirLg launching and rigorous orbital temperature environment, the kinematic parameters of space robot may be largely deviated from their nominal parameters. The disparity will cause the real pose (including position and orientation) of the end effector not to match the desired one, and further hinder the space robot from performing the scheduled mission. To improve pose accuracy of space robot, a new self-calibration method using the distance measurement provided by a laser-ranger fixed on the end-effector is proposed. A distance-measurement model of the space robot is built according to the distance from the starting point of the laser beam to the intersection point at the declining plane. Based on the model, the cost function about the pose error is derived. The kinematic calibration is transferred to a non-linear system optimization problem, which is solved by the improved differential evolution (DE) algoritlun. A six-degree of freedom (6-DOF) robot is used as a practical simulation example, and the simulation results show: 1) A significant improvement of pose accuracy of space robot can be obtained by distance measurement only; 2) Search efficiency is increased by improved DE; 3) More calibration configurations may make calibration results better. 展开更多
关键词 space robot SELF-CALIBRATION laser ranger pose accuracy improved differential evolution
下载PDF
Research of Sail Height Adjustment on Sail-Assisted Ship in Different Loading and Wind Conditions
8
作者 HE Jianhai HU Yihuai +1 位作者 TANG Juanjuan ZHANG Jianxia 《Journal of Shipping and Ocean Engineering》 2016年第6期313-322,共10页
The relationship between ship stability and sail area is firstly investigated based on the sail-assisted ship's stability in this paper. Then a height-adjustable sail structure is proposed that could be automatically... The relationship between ship stability and sail area is firstly investigated based on the sail-assisted ship's stability in this paper. Then a height-adjustable sail structure is proposed that could be automatically adjusted according to the wind conditions, ship loading and other requirements. The influences on the sail height in different ship load conditions, different wind apparent velocity and wind direction are analyzed of a sail-assisted bulk carrier. Finally a control procedure of sail height adjustment in real time is proposed according to the actual load conditions, wind conditions, ship velocity and other parameters to make the best use of wind energy, which is significant for the practical application of sail-assisting technology in the future. 展开更多
关键词 Sail height height adjustable wind influential factor control procedure.
下载PDF
Global Solutions of Shock Reflection by Wedges for the Nonlinear Wave Equation
9
作者 Xuemei DENG Wei XIANG 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2011年第5期643-668,共26页
When a plane shock hits a wedge head on, it experiences a reflection-diffraction process and then a self-similar reflected shock moves outward as the original shock moves forward in time. In this paper, shock reflecti... When a plane shock hits a wedge head on, it experiences a reflection-diffraction process and then a self-similar reflected shock moves outward as the original shock moves forward in time. In this paper, shock reflection by large-angle wedges for compressible flow modeled by the nonlinear wave equation is studied and a global theory of existence, stability and regularity is established. Moreover, C^0,1 is the optimal regularity for the solutions across the degenerate sonic boundary. 展开更多
关键词 Compressible flow Conservation laws Nonlinear wave system Regularreflection
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部