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A simplified model for extreme-wave kinematics in deep sea 被引量:1
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作者 滕斌 宁德志 《Journal of Marine Science and Application》 2009年第1期27-32,共6页
Based on the fifth-order Stokes regular wave theory, a simplified model for extreme-wave kinematics in deep sea was developed. In this model, from the wave records the average of two neighboring wave periods for the e... Based on the fifth-order Stokes regular wave theory, a simplified model for extreme-wave kinematics in deep sea was developed. In this model, from the wave records the average of two neighboring wave periods for the extreme crest or trough was defined as the period of the Stokes wave by the up and down zero-crossing methods. Then the input wave amplitude was deduced by substituting the wave period and extreme crest or trough into the expression for the fifth-order Stokes wave elevation. Thus the corresponding formula for the wave velocity can be used to describe kinematics beneath the extreme wave. By comparison with the published numerical models and experimental data, the proposed model is validated to be able to calculate the extreme wave velocity rather easily and accurately. 展开更多
关键词 extreme wave deep sea fifth-order Stokes regular wave KINEMATICS velocity field
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FRACTAL KINEMATICS OF CRACK PROPAGATION IN GEOMATERIALS 被引量:5
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作者 谢和平 《Journal of China University of Mining and Technology》 1995年第1期1-8,共8页
Experimental results indicate that propagation paths of cracks in geomaterials are often irregular. producing rough fracture surfaces which are fractal. A formula is derived for the fractal kinematics of crack propaga... Experimental results indicate that propagation paths of cracks in geomaterials are often irregular. producing rough fracture surfaces which are fractal. A formula is derived for the fractal kinematics of crack propagation in geomaterials. The formula correlates the dynamic and static fracture toughnesses with crack velocity, crack length and a microstructural parameter, and allows the fractal dimension to be obtained. From the equations for estimating crack velocity and fractal dimension it can be shown that the measured crack ve1ocity, Vo, should be much smaller than the fractal crack velocity, V. It can also be shown that the fractal dimension of the crack propagation path can be calculated directly from Vo and from the fracture toughness. 展开更多
关键词 fractal kinematics crack propagation fractal geometry
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Numerical simulation of bubble chaotic motion in a cavitating water jet 被引量:5
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作者 卢义玉 《Journal of Chongqing University》 CAS 2003年第1期91-94,共4页
A computational fluid dynamics (CFD) method is developed to investigate the radical motion of single cavitating bubble in the oscillating pressure field of a cavitating water jet. Regarding water as a compressible flu... A computational fluid dynamics (CFD) method is developed to investigate the radical motion of single cavitating bubble in the oscillating pressure field of a cavitating water jet. Regarding water as a compressible fluid, the simulation is performed at different oscillating frequencies. It is found that the bubble motion presents obvious nonlinear feature, and bifurcation and chaos appear on some conditions. The results manifest the indetermination of the cavitating bubble motion in the oscillating pressure field of the cavitating water jet. 展开更多
关键词 cavitating water jet cavitating bubble motion numerical simulation
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Video-Based Crowd Density Estimation and Prediction System for Wide-Area Surveillance 被引量:2
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作者 曹黎俊 黄凯奇 《China Communications》 SCIE CSCD 2013年第5期79-88,共10页
Crowd density estimation in wide areas is a challenging problem for visual surveillance. Because of the high risk of degeneration, the safety of public events involving large crowds has always been a major concern. In... Crowd density estimation in wide areas is a challenging problem for visual surveillance. Because of the high risk of degeneration, the safety of public events involving large crowds has always been a major concern. In this paper, we propose a video-based crowd density analysis and prediction system for wide-area surveillance applications. In monocular image sequences, the Accumulated Mosaic Image Difference (AMID) method is applied to extract crowd areas having irregular motion. The specific number of persons and velocity of a crowd can be adequately estimated by our system from the density of crowded areas. Using a multi-camera network, we can obtain predictions of a crowd's density several minutes in advance. The system has been used in real applications, and numerous experiments conducted in real scenes (station, park, plaza) demonstrate the effectiveness and robustness of the proposed method. 展开更多
关键词 crowd density estimation prediction system AMID visual surveillance
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Irregular Segmented Region Compression Coding Based on Pulse Coupled Neural Network
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作者 MA Yi-de QI Chun-liang +2 位作者 QIAN Zhi-bai SHI Fei ZHANG Bei-dou 《Semiconductor Photonics and Technology》 CAS 2006年第2期110-116,130,共8页
An irregular segmented region coding algorithm based on pulse coupled neural network(PCNN) is presented. PCNN has the property of pulse-coupled and changeable threshold, through which these adjacent pixels with approx... An irregular segmented region coding algorithm based on pulse coupled neural network(PCNN) is presented. PCNN has the property of pulse-coupled and changeable threshold, through which these adjacent pixels with approximate gray values can be activated simultaneously. One can draw a conclusion that PCNN has the advantage of realizing the regional segmentation, and the details of original image can be achieved by the parameter adjustment of segmented images, and at the same time, the trivial segmented regions can be avoided. For the better approximation of irregular segmented regions, the Gram-Schmidt method, by which a group of orthonormal basis functions is constructed from a group of linear independent initial base functions, is adopted. Because of the orthonormal reconstructing method, the quality of reconstructed image can be greatly improved and the progressive image transmission will also be possible. 展开更多
关键词 Pulse coupled neural network SEGMENTATION Orthonormal basis Compression coding possible.
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Searching for Strange Attractor in Sliver Irregularity Series
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作者 姚杰 钟再敏 +1 位作者 陈人哲 叶国铭 《Journal of Donghua University(English Edition)》 EI CAS 2007年第6期718-722,共5页
The chaotic nonlinear time series method is applied to analyze the sliver irregularity in textile processing.Because it unifies the system's determinacy and randomness,it seems more adaptive to describe the sliver... The chaotic nonlinear time series method is applied to analyze the sliver irregularity in textile processing.Because it unifies the system's determinacy and randomness,it seems more adaptive to describe the sliver irregularity than conventional methods.Firstly,the chaos character,i.e.fractal dimension,positive Lyapunov exponent,and state space parameters,including time delay and reconstruction dimension,are calculated respectively.As a result,a positive Lyapunov exponent and a fractal dimension are obtained,which demonstrates that the system is chaotic in fact.Secondly,both local linear forecast and global forecast models based on the reconstructed state are adopted to predict a segment part of the sliver irregularity series,which proves the validity of this analysis.Therefore,the sliver irregularity series shows the evidence of chaotic phenomena,and thus laying the theoretical foundation for analyzing and modeling the sliver irregularity series by applying the chaos theory,and providing a new way to understand the complexity of the sliver irregularity much better. 展开更多
关键词 sliver irregularity CHAOS state space reconstruction time delay the maximal Lyapunov exponent fractal dimension local linear forecast global forecast neural network
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An Improved Walk Model for Train Movement on Railway Network
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作者 LI Ke-Ping MAO Bo-Hua GAO Zi-You 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第6期979-984,共6页
In this paper, we propose an improved walk model for simulating the train movement on railway network. In the proposed method, walkers represent trains. The improved walk model is a kind of the network-based simulatio... In this paper, we propose an improved walk model for simulating the train movement on railway network. In the proposed method, walkers represent trains. The improved walk model is a kind of the network-based simulation analysis model. Using some management rules for walker movement, walker can dynamically determine its departure and arrival times at stations. In order to test the proposed method, we simulate the train movement on a part of railway network. The numerical simulation and analytical results demonstrate that the improved model is an effective tool for simulating the train movement on railway network. Moreover, it can well capture the characteristic behaviors of train scheduling in railway traffic. 展开更多
关键词 train movement random-walk model train timetable
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Development of Independent Moving Puppet Robot
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作者 Byeong-yeol KIM Hwan-ik CHUNG Hern-soo HAHN 《Journal of Measurement Science and Instrumentation》 CAS 2010年第4期364-367,共4页
This paper is about the automation of the marionette performance. A method to solve the problem on the mobility of the automated marionette performance is proposed. Since it is difficult to control the marionette by h... This paper is about the automation of the marionette performance. A method to solve the problem on the mobility of the automated marionette performance is proposed. Since it is difficult to control the marionette by hands, as an alternative, the automated marionette is studied. However, the automtic marionette performance is limited in the silence and mobility. Therefore, an independent shifter to move freely on the stage is required. The magnetic device which connects the movable robot and the marionette controlling robot is conceived. The magnetic device is improved and applied by considering the features of the marionette robot, which is the irregular movement of the marionette controller and of the parallel limited area. The burden of being trapped on the magnet is minimized by dividing the robot to the upper and lower parts of the marionette performance stage. The direction of the magnet is considered to make the mobile robot to move freely. Thus, the efficiency and safety of the device is confirmed by balancing the strength with the permanent magnet. 展开更多
关键词 MARIONETTE MAGNET mobile robot PUPPET
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Kingship in Nepal: Envisioning a Contemporary Perspective
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作者 Purna Bahadur Karki 《Sociology Study》 2012年第9期675-687,共13页
The aim of this study is to observe the prospect of kingship in Nepal. It presents an analysis of the people's perspective on dismissed monarchy and challenges faced by Nepal. There was little voice on Nepali monarch... The aim of this study is to observe the prospect of kingship in Nepal. It presents an analysis of the people's perspective on dismissed monarchy and challenges faced by Nepal. There was little voice on Nepali monarchy system, yet many individuals and researcher expressed the need for monarchy to build nation and keep its culture, tradition, and nation unity. To promote the democratic system, political parties should practice democratic norms and respect rules of law in real life rather than just in talk. For the express of people voice and envision prosperous Nepal, this paper attempts to contribute to the need of monarchy back in Nepal far its savereignty and unity. The paper gives a historical overview of kingship in Nepal and discusses incompetent political parties and the importance of monarchy in Nepal. It identifies that to unite the Nepal and Nepali and give the nation social cultural identity, and it needs any form of monarchy in Nepal. The past and present, despite of political systems, social movement, and practice seen from the political parties were failed several times to fulfill people's mandate, such as holding election, writing constitution. The fields discussed in the paper include apathetic attitude of the political parties toward establishing peace and stability in Nepal. 展开更多
关键词 KINGSHIP NATIONALISM conflict resolution CONSTITUTION
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A nonlinear hydroelastic method considering wave memory effect for ship load responses in irregular waves
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作者 陈占阳 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第9期2058-2070,共13页
Since the amplitude and frequency of irregular waves change with time,great difficulties are brought for solving ship load responses in random waves.To take the effect of various frequencies of irregular waves into co... Since the amplitude and frequency of irregular waves change with time,great difficulties are brought for solving ship load responses in random waves.To take the effect of various frequencies of irregular waves into consideration in load responses of hull,the wave memory effect is necessary.A semi-analytical method is introduced for the time-domain retardation functions,and then a nonlinear hydroelastic method considering memory effect for ships in irregular waves is proposed.Segmented self-propelling model experiments of a container ship were carried out in a towing tank,a ship motion measuring device for self-propelling model test was designed.Whipping responses of the ship in regular and irregular waves are analyzed.Finally,the calculation results are compared with those measured by segmented model experiments,and the result indicates that the memory effect has little effect on load responses of ship in regular waves,but pronounced effect on results in irregular waves.Moreover,the presented method is reasonable for the prediction of ship load responses in irregular waves. 展开更多
关键词 HYDROELASTICITY memory effect retardation function segmented self-propelling model test irregular waves
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Studies on the impact of the evolution of Volleyball Rules upon technology and tactics
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作者 Shumao LAN 《International Journal of Technology Management》 2015年第2期22-24,共3页
As it developed to today, Volleyball evolved from a game for the purpose of entertainment initially to a competitive Olympic sport. Through various periods of Volleyball development, we can find that when some old rul... As it developed to today, Volleyball evolved from a game for the purpose of entertainment initially to a competitive Olympic sport. Through various periods of Volleyball development, we can find that when some old rules can not adapt to the volleyball development, it will lead to changes in the rules, it is this continuous improvement and change that inject vigor to volleyball and bring vitality, and promote the innovative development of volleyball skills and tactics, in turn the constant enrichment and development of volleyball skills and tactics required the game rules constantly revised and improved, as promoted and restricted each other, analysis of the mutual relationship between volleyball game rules and technology or tactics can not only in favor of volleyball skills, like evolving tactics, but also beneficial to volleyball competition rules maturity. Development of Volleyball Rules has been the inexhaustible power to development of sports project, researching of the competition rules has been recognized as a major breakthrough in the field of sports in various projects to promote sports development. Volleyball Rules - from the generated moment until today, has evolved many times. This evolution is not blind, random; it follows its inherent rule. A contest rule, which has a close relationship with the development of sports technology, are the basic norms and principles of sports game. They promote each other, while mutually restraint. Analysis of the relationship between volleyball competition rules and the technology or tactics, is not only conducive to the development of athletic skills, but also to the maturity of competition rules. 展开更多
关键词 volleyball rules competition evolution
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A Framework of LSTM Neural Network Model in Multi-Time Scale Real-Time Prediction of Ship Motions in Head Waves
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作者 CHEN Zhan-yang ZHAN Zheng-yong +2 位作者 CHANG Shao-ping XU Shao-feng LIU Xing-yun 《船舶力学》 EI 2024年第12期1803-1819,共17页
Ship motions induced by waves have a significant impact on the efficiency and safety of offshore operations.Real-time prediction of ship motions in the next few seconds plays a crucial role in performing sensitive act... Ship motions induced by waves have a significant impact on the efficiency and safety of offshore operations.Real-time prediction of ship motions in the next few seconds plays a crucial role in performing sensitive activities.However,the obvious memory effect of ship motion time series brings certain difficulty to rapid and accurate prediction.Therefore,a real-time framework based on the Long-Short Term Memory(LSTM)neural network model is proposed to predict ship motions in regular and irregular head waves.A 15000 TEU container ship model is employed to illustrate the proposed framework.The numerical implementation and the real-time ship motion prediction in irregular head waves corresponding to the different time scales are carried out based on the container ship model.The related experimental data were employed to verify the numerical simulation results.The results show that the proposed method is more robust than the classical extreme short-term prediction method based on potential flow theory in the prediction of nonlinear ship motions. 展开更多
关键词 deep learning LSTM ship motion real-time prediction irregular waves
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你也有机会飞出世界级纪录
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作者 张汝煐 《环球飞行》 2003年第9期76-77,共2页
关键词 飞机 飞行竞赛 飞行训练 世界记录 《运动规则》 国际航空联合会
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