期刊文献+
共找到166篇文章
< 1 2 9 >
每页显示 20 50 100
释“动” 被引量:1
1
作者 宋艳欣 王蒴 《潍坊教育学院学报》 2009年第1期25-27,共3页
"动"字最早见于毛公鼎的金文,"动"之本义为背得动,引申为改变原来的位置或状态,表示移动、摇动、振动,并通过隐喻和转喻的综合作用产生了"动"的一词多义。"动"字的多个义项之间以认知原型为中... "动"字最早见于毛公鼎的金文,"动"之本义为背得动,引申为改变原来的位置或状态,表示移动、摇动、振动,并通过隐喻和转喻的综合作用产生了"动"的一词多义。"动"字的多个义项之间以认知原型为中心,呈现出放射性的发展模式。 展开更多
关键词 “动”字 认知原型 隐喻 转喻
下载PDF
Enabling Technologies for Autonomous Robotic Systems in Manufacturing
2
作者 ERDŐS Gábor ABAI Kristóf +17 位作者 BEREGI Richárd CSEMPESZ János CSERTEG Tamás GODÓGábor HAJÓS Mátyás HÁY Borbála HORVÁTH Dániel HORVÁTH Gergely JUNIKIÁdám KEMÉNY Zsolt KOVÁCS András NACSA János PANITI Imre PEDONE Gianfranco TAKÁCS Emma TIPARY Bence ZAHORÁN László VÁNCZA József 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2024年第4期403-431,共29页
Research of autonomous manufacturing systems is motivated both by the new technical possibilities of cyber-physical systems and by the practical needs of the industry.Autonomous operation in semi-structured industrial... Research of autonomous manufacturing systems is motivated both by the new technical possibilities of cyber-physical systems and by the practical needs of the industry.Autonomous operation in semi-structured industrial environments can now be supported by advanced sensor technologies,digital twins,artificial intelligence and novel communication techniques.These enable real-time monitoring of production processes,situation recognition and prediction,automated and adaptive(re)planning,teamwork and performance improvement by learning.This paper summarizes the main requirements towards autonomous industrial robotics and suggests a generic workflow for realizing such systems.Application case studies will be presented from recent practice at HUN-REN SZTAKI in a broad range of domains such as assembly,welding,grinding,picking and placing,and machining.The various solutions have in common that they use a generic digital twin concept as their core.After making general recommendations for realizing autonomous robotic solutions in the industry,open issues for future research will be discussed. 展开更多
关键词 industrial robotics AUTONOMY digital twin enabling technology
下载PDF
Imaging simulation and analysis of attitude jitter effect on topographic mapping for lunar orbiter stereo optical cameras
3
作者 CHEN Chen TONG Xiao-Hua +4 位作者 LIU Shi-Jie YE Zhen HUANG Chao-Wei WU Hao ZHANG Han 《红外与毫米波学报》 SCIE EI CAS CSCD 北大核心 2024年第5期722-730,共9页
The geometric accuracy of topographic mapping with high-resolution remote sensing images is inevita-bly affected by the orbiter attitude jitter.Therefore,it is necessary to conduct preliminary research on the stereo m... The geometric accuracy of topographic mapping with high-resolution remote sensing images is inevita-bly affected by the orbiter attitude jitter.Therefore,it is necessary to conduct preliminary research on the stereo mapping camera equipped on lunar orbiter before launching.In this work,an imaging simulation method consid-ering the attitude jitter is presented.The impact analysis of different attitude jitter on terrain undulation is conduct-ed by simulating jitter at three attitude angles,respectively.The proposed simulation method is based on the rigor-ous sensor model,using the lunar digital elevation model(DEM)and orthoimage as reference data.The orbit and attitude of the lunar stereo mapping camera are simulated while considering the attitude jitter.Two-dimensional simulated stereo images are generated according to the position and attitude of the orbiter in a given orbit.Experi-mental analyses were conducted by the DEM with the simulated stereo image.The simulation imaging results demonstrate that the proposed method can ensure imaging efficiency without losing the accuracy of topographic mapping.The effect of attitude jitter on the stereo mapping accuracy of the simulated images was analyzed through a DEM comparison. 展开更多
关键词 topographic mapping lunar orbiter stereo camera attitude jitter imaging simulation digital elevation model
下载PDF
New Method to Restrain Pumping Voltage of Braking Procedure for Brushless DC Motor of Electric Armored Vehicle 被引量:3
4
作者 郑慕侨 宋小庆 +1 位作者 孙德福 臧克茂 《Journal of Beijing Institute of Technology》 EI CAS 2002年第2期137-141,共5页
In order to restrain the high pumping voltage of braking procedure which is harmful to the system of electric armored vehicle. Based on the analysis of pumping voltage of the braking procedure, the relation between pu... In order to restrain the high pumping voltage of braking procedure which is harmful to the system of electric armored vehicle. Based on the analysis of pumping voltage of the braking procedure, the relation between pumping voltage and PWM ratio is derived and a new digital control method to restrain the pumping voltage by changing PWM ratio is put forward. Because the capacitance is decreased effectively, the volume of controller is reduced and the performance to price ratio is improved. The results of computer simulation and experiment proved that this method is feasible and valid. 展开更多
关键词 electrical armored vehicle brushless DC motor regenerative braking
下载PDF
Fish maneuver analysis system based on sequence images 被引量:2
5
作者 蒋明 何小元 《Journal of Southeast University(English Edition)》 EI CAS 2009年第2期228-231,共4页
The aim is to establish an automatic system to analyze the maneuver performance of fish. A high speed camera (1 000 frame/s) is employed to record fast-start maneuver. Three steps are taken to analyze the kinematics... The aim is to establish an automatic system to analyze the maneuver performance of fish. A high speed camera (1 000 frame/s) is employed to record fast-start maneuver. Three steps are taken to analyze the kinematics: first, the midline in the first image is partitioned into equal interval lengths and the coordinates of all inter segmental points are saved. Secondly, these points coordinates are searched in the next frame with the digital image correlation (DIC) method, then these points are fitted with a spline curve function. Repeat this step until all the midlines are figured out frame by frame. Finally, according to the variety of midlines, the kinematics of the fast-start is calculated. Using this system to test carp C-start, the duration is divided into two stages: stage 1 is defined as the formation of the C shape and stage 2 as the return flip of the tail followed with forward motion. By tracing the middle line, the kinematic parameters of turning rate, centre of mass (CM) turning rate, CM turning radius, etc. are obtained. 展开更多
关键词 CARP MANEUVER KINEMATICS digital image CORRELATION
下载PDF
CNC SYSTEM OF FLEXIBLE FIXTURE IN AIRCRAFT COMPONENT MANUFACTURING AND ASSEMBLY 被引量:2
6
作者 郇极 靳阳 肖文磊 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2012年第1期54-61,共8页
The computer numerical control(CNC) system is suited to control varied types of flexible fixtures in aircraft component manufacturing and assembly. The mechanisms and control requirements of flexible fixtures are pr... The computer numerical control(CNC) system is suited to control varied types of flexible fixtures in aircraft component manufacturing and assembly. The mechanisms and control requirements of flexible fixtures are presented and analyzed. The hardware and software architecture and implementation of CNC system are pro- posed. The flexible fixture mechanism is described using configuration parameters. According to the parameters, the CNC system automatically generates the control feature and the human machine interface (HMI) operation function. The CNC system is implemented in a flexible fixture for skin-strlnger assembly, and results show the effectiveness of the system. 展开更多
关键词 computer numerical control(CNC) motion control aircraft assembly flexible fixture
下载PDF
Design and implementation of digital closed-loop drive control system of a MEMS gyroscope 被引量:5
7
作者 王晓雷 李宏生 杨波 《Journal of Southeast University(English Edition)》 EI CAS 2012年第1期35-40,共6页
In order to effectively control the working state of the gyroscope in drive mode, the drive characteristics of the micro electromechanical system (MEMS) gyroscope are analyzed in principle. A novel drive circuit for... In order to effectively control the working state of the gyroscope in drive mode, the drive characteristics of the micro electromechanical system (MEMS) gyroscope are analyzed in principle. A novel drive circuit for the MEMS gyroscope in digital closed-loop control is proposed, which utilizes a digital phase-locked loop (PLL) in frequency control and an automatic gain control (AGC) method in amplitude control. A digital processing circuit with a field programmable gate array (FPGA) is designed and the experiments are carried out. The results indicate that when the temperature changes, the drive frequency can automatically track the resonant frequency of gyroscope in drive mode and that of the oscillating amplitude holds at a set value. And at room temperature, the relative deviation of the drive frequency is 0.624 ×10^-6 and the oscillating amplitude is 8.0 ×10^-6, which are 0. 094% and 18. 39% of the analog control program, respectively. Therefore, the control solution of the digital PLL in frequency and the AGC in amplitude is feasible. 展开更多
关键词 micro electromechanical system (MEMS) digitalgyroscope drive frequency phase-locked loop (PLL) oscillating amplitude automatic gain control (AGC)
下载PDF
A New CMOS Image Sensor with a High Fill Factor and the Dynamic Digital Double Sampling Technique
8
作者 刘宇 王国裕 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2006年第2期313-317,共5页
A single CMOS image sensor based on a 0.35μm process along with its design and implementation is introduced. The architecture of an active pixel sensor is used in the chip. The fill factor of a pixel cell can reach 4... A single CMOS image sensor based on a 0.35μm process along with its design and implementation is introduced. The architecture of an active pixel sensor is used in the chip. The fill factor of a pixel cell can reach 43%,higher than the traditional factor of 30%. Moreover, compared with the conventional method whose fixed pattern noise (FPN) is around 0.5%, a dynamic digital double sampling technique is developed, which possesses simpler circuit architecture and a better FPN suppression outcome. The CMOS image sensor chip is implemented in the 0.35μm mixed signal process of a Chartered by MPW. The experimental results show that the chip operates welt,with an FPN of about 0.17%. 展开更多
关键词 active pixel CMOS image sensor fill factor dynamic digital double sampling fixed pattern noise
下载PDF
Study on the Comparison of Arthropod Communities in Three Kinds of Cruciferous Vegetable Fields at High Mountainous Area 被引量:7
9
作者 王香萍 李传仁 王福莲 《Agricultural Science & Technology》 CAS 2008年第1期8-10,共3页
[Objective]This research aimed to compare arthropod communities in different cruciferous vegetable fields at high mountainous area and provide guidance for pest control. [Method] The main arthropod species in 3 kinds ... [Objective]This research aimed to compare arthropod communities in different cruciferous vegetable fields at high mountainous area and provide guidance for pest control. [Method] The main arthropod species in 3 kinds of erueiferous vegetable fields at high mountainous area were investigated, the composition of arthropod community in different vegetable fields were analyzed. [Result] The main arthropod species in erueiferous vegetables fields at high mountainous area were similar, but had different quantity compositions. The richness was the highest in radish field. [Conclusion] Crop species had great influence on biological community; we should focus on the main pests in the process of pest control. 展开更多
关键词 Cruciferous vegetable ARTHROPOD COMMUNITY
下载PDF
西汉结果补语的发展 被引量:5
10
作者 梁银峰 《古汉语研究》 CSSCI 北大核心 2005年第1期34-40,共7页
西汉时期获得长足发展的使成格式"V1+V2+O"并非动补结构,而是连动结构。在非使成式结果补语中,一个引人注目的变化是"得"字结果补语的产生。
关键词 结果补语 结构 补结构 使成式 格式 目的 西汉时期
下载PDF
Design and Development of the DTC Induction Motor Drive for Electric Vehicle
11
作者 孙逢春 程夕明 《Journal of Beijing Institute of Technology》 EI CAS 2000年第4期415-421,共7页
The design and development of the traction controller for electric vehicle is introduced, which is based on the induction motor. This drive is developed by using a digital signal processor at low cost and carried out ... The design and development of the traction controller for electric vehicle is introduced, which is based on the induction motor. This drive is developed by using a digital signal processor at low cost and carried out with the module design concept of both software and hardware. Nevertheless, a scheme of the sensorless direct torque control is based on the developed hardware, of which the feasibility is tested by a trial program. Additionally, both the interface function of the drive hardware and the feasibility of its software are proved to be good by the trail programs. A test motor can run about 18?r/min by a variable frequency program with the space vector pulse width modulation technology, of which the torque is visible pulsatile. In this presentation, based on the theoretical approach, the sensorless torque control is to be studied and applied to electric vehicles, of which the quick, smooth and stable torque response is emphasized because it quite benefits improving the drive performance of electric vehicles. 展开更多
关键词 electric vehicle induction motor digital signal processor direct torque control
下载PDF
Reachability analysis of web service compositions via NWA 被引量:1
12
作者 杜旭涛 邢春晓 周立柱 《Journal of Southeast University(English Edition)》 EI CAS 2008年第3期293-295,共3页
In order to improve the design and implementation quality of web service compositions,formal methods are used to model them and certain properties are verified.WCFA (web service interface control flow automata)is us... In order to improve the design and implementation quality of web service compositions,formal methods are used to model them and certain properties are verified.WCFA (web service interface control flow automata)is used to model web services,especially the control flow and possible interactions with other web services.A web service composition consists of a set of interacting WCFA.The global behavior of web service compositions is captured by NWA(nested word automata).A variation of the depth-first search algorithm is used to transform a set of WCFA into an NWA.State formulae and call stacks at each node of NWA are computed by a path-sensitive reachability analysis.Safety properties,call stack inspection properties and pre/post-conditions of service invocations are described by assertions.Then verification of these assertions is carried out by an automated SAT tool. 展开更多
关键词 web service composition FORMALISM nested word automata (NWA) web service interface control flow automata (WCFA) VERIFICATION
下载PDF
Influence of Diesel Nozzle Geometry on Cavitation Using Eulerian Multi-Fluid Method 被引量:3
13
作者 张军 杜青 杨延相 《Transactions of Tianjin University》 EI CAS 2010年第1期33-39,共7页
Dependent on automatically generated unstructured grids, a comprehensive computational fluid dynamics(CFD)numerical simulation is performed to analyze the influence of nozzle geometry on the internal flow characterist... Dependent on automatically generated unstructured grids, a comprehensive computational fluid dynamics(CFD)numerical simulation is performed to analyze the influence of nozzle geometry on the internal flow characteristics of a multi-hole diesel injector with the multi-phase flow model based on Eulerian multi-fluid method.The diesel components in nozzle are considered as two continuous phases, diesel liquid and diesel vapor respectively.Considering that both of them are fully coupled and interpenetrated, sepa... 展开更多
关键词 diesel injection CAVITATION nozzle geometry multi-phase flow numerical simulation
下载PDF
HIT prosthetic hand based on tendon-driven mechanism 被引量:4
14
作者 刘伊威 丰飞 高一夫 《Journal of Central South University》 SCIE EI CAS 2014年第5期1778-1791,共14页
An underactuated finger structure actuated by tendon-driven system is presented.Kinematics and static analysis of the finger is done,and the results indicate that the prosthetic finger structure is effective and feasi... An underactuated finger structure actuated by tendon-driven system is presented.Kinematics and static analysis of the finger is done,and the results indicate that the prosthetic finger structure is effective and feasible.Based on the design of finger,a prosthetic hand is designed.The hand is composed of 5 independent fingers and it looks more like humanoid.Its size is about 85% of an adult's hand and weights about 350 g.Except the thumb finger,each finger is actuated by one DC motor,gear head and a tendon,and has three curling/extension joints.The thumb finger which is different from other existing prostheses is a novel design scheme.The thumb finger has four joints including three curling/extension joints and a joint which is used to realize the motion of the thumb related to the palm,and these joints are also driven by one DC motor,harmonic drive and a tendon.The underactuation and adaptive curling/extension motion of the finger are realized by joint torsion springs.A high-powered chip of digital signal processing(DSP)is the main part of the electrical system which is used for the motors control,data collection,communication with external controlling source,and so on.To improve the reliability of the hand,structures and sensors are designed and made as simply as possible.The hand has strong manipulation capabilities that have been verified by finger motion and grasping tests and it can satisfy the daily operational needs and psychological needs of deformities. 展开更多
关键词 prosthetic hand tendon-driven mechanism underactuation kinematics and static analysis
下载PDF
Measuring the Condition of Parking Lot by Image Processing
15
作者 吴大勇 魏平 侯朝桢 《Journal of Beijing Institute of Technology》 EI CAS 1999年第3期232-237,共6页
Aim To study the parking management in the condition of vehicles' increasing. Methods The methods of pattern recognition and image processing were used to analyze the eigenvalues of parking lot images. Results ... Aim To study the parking management in the condition of vehicles' increasing. Methods The methods of pattern recognition and image processing were used to analyze the eigenvalues of parking lot images. Results The automatic identification of every parking place in the parking plot was realized. The automatic measuring of parked vehicle count and parking lot utilization was completed. Conclusion It can complete the real time recognition, and has some practicabilities. 展开更多
关键词 automatic measuring digital image processing pattern recognition
下载PDF
Fractal Measures of Drainage Network to Investigate Surface Deformation from Remote Sensing Data: A Paradigm from Hindukush (NE-Afghanistan) 被引量:3
16
作者 Syed Amer MAHMOOD Richard GLOAGUEN 《Journal of Mountain Science》 SCIE CSCD 2011年第5期641-654,共14页
This approach represents the relative susceptibility of the topography of the earth to active deformation by means of geometrical distinctiveness of the river networks. This investigation employs the fractal analysis ... This approach represents the relative susceptibility of the topography of the earth to active deformation by means of geometrical distinctiveness of the river networks. This investigation employs the fractal analysis of drainage system extracted from ASTER Global Digital Elevation Model (GDEM-30m resolution). The objective is to mark active structures and to pinpoint the areas robustly influenced by neotectonics. This approach was examined in the Hindukush, NE-Afghanistan. This region is frequently affected by deadly earthquakes and the modern fault activities and deformation are driven by the collision between the northward-moving Indian subcontinent and Eurasia. This attempt is based on the fact that drainage system is strained to linearize due to neotectonic deformation. Hence, the low fractal dimensions of the Kabul, Panjsher, Laghman, Andarab, Alingar and Kocha Rivers are credited to active tectonics. A comprehensive textural examination is conducted to probe the linearization, heterogeneity and connectivity of the drainage patterns. The aspects for these natural textures are computed by using the fractal dimension (FD), lacunarity (LA) and succolarity (SA) approach. All these methods are naturally interrelated, i.e. objects with similar FD can be further differentiated with LA and/or SA analysis. The maps of FD, LA and SA values are generated by using a sliding window of 50 arc seconds by 50 arc seconds (50" × 50"). Afterwards, the maps are interpreted in terms of regional susceptibility to neotectonics. This method is useful to pinpoint numerous zones where the drainage system is highly controlled by Hindukush active structures. In the North-Northeast of the Kabul block, we recognized active tectonic blocks. The region comprising, Kabul, Panjsher, Andrab, Alingar and Badakhshan is more susceptible to damaging events. This investigation concludes that the fractal analysis of the river networks is a bonus tool to localize areas vulnerable to deadly incidents influencing the Earth’s topography and consequently intimidate human lives. 展开更多
关键词 FRACTAL Drainage network LACUNARITY Succolarity Surface deformation and Hindukush
下载PDF
Design and implementation of GM- APD array readout circuit for infrared imaging
17
作者 吴金 袁德军 +3 位作者 王灿 陈浩 郑丽霞 孙伟锋 《Journal of Southeast University(English Edition)》 EI CAS 2016年第1期11-15,共5页
Based on an avalanche photodiode( APD) detecting array working in Geiger mode( GM-APD), a high-performance infrared sensor readout integrated circuit( ROIC) used for infrared 3D( three-dimensional) imaging is ... Based on an avalanche photodiode( APD) detecting array working in Geiger mode( GM-APD), a high-performance infrared sensor readout integrated circuit( ROIC) used for infrared 3D( three-dimensional) imaging is proposed. The system mainly consists of three functional modules, including active quenching circuit( AQC), time-to-digital converter( TDC) circuit and other timing controller circuit. Each AQC and TDC circuit together constitutes the pixel circuit. Under the cooperation with other modules, the current signal generated by the GM-APD sensor is detected by the AQC, and the photon time-of-flight( TOF) is measured and converted to a digital signal output to achieve a better noise suppression and a higher detection sensitivity by the TDC. The ROIC circuit is fabricated by the CSMC 0. 5 μm standard CMOS technology. The array size is 8 × 8, and the center distance of two adjacent cells is 100μm. The measurement results of the chip showthat the performance of the circuit is good, and the chip can achieve 1 ns time resolution with a 250 MHz reference clock, and the circuit can be used in the array structure of the infrared detection system or focal plane array( FPA). 展开更多
关键词 infrared 3D(three-dimensional) imaging readout integrated circuit(ROIC) Geiger mode avalanche photodiode active quenching circuit(AQC) time-to-digital converter(TDC)
下载PDF
A study on the feasibility of CET oral test based on automatic essay marking
18
作者 刘健刚 郑玉琪 +2 位作者 陈美华 姜浩 赵力 《Journal of Southeast University(English Edition)》 EI CAS 2012年第4期410-414,共5页
This paper discusses the approach to the CET (college English test) oral test based on automatic essay marking (AEM). The reliability and validity arouses a dispute on Internet-based CET (iB-CET) oral test in Ch... This paper discusses the approach to the CET (college English test) oral test based on automatic essay marking (AEM). The reliability and validity arouses a dispute on Internet-based CET (iB-CET) oral test in China, leading to the penetration into oral test contents in dialogue, description or comment, and question answering. Then, a probe into transformation from a spoken document into a textual document is touched on a conversion ratio of 72% adopted at the present time, AEM to be carried forward being a necessary hypothesis for Afterwards, this paper focuses on the pipeline in AEM with the content features and the language itself, which is established in two different models in marking for extraction and detection. Through experiments, this paper reveals the fact that an iB-CET oral test can be performed perfectly in the pipeline of spoken documents transformed into textual documents which can be automatically marked. Hence the design of the iB-CET oral test reaches its reliability and validity. 展开更多
关键词 reliability and validity spoken document and textual document automatic essay marking
下载PDF
Dynamic experiment and numerical simulation of solute transmission in heap leaching processing 被引量:3
19
作者 刘金枝 吴爱祥 +1 位作者 杨保华 江怀春 《Journal of Central South University of Technology》 EI 2007年第6期838-841,共4页
Solute transmission in saturated ore heap was studied numerically and experimentally. The convection-diffusion equation (CDE) used to describe the mass transportation in porous media was solved by characteristic diffe... Solute transmission in saturated ore heap was studied numerically and experimentally. The convection-diffusion equation (CDE) used to describe the mass transportation in porous media was solved by characteristic difference method to give the distribution of the concentration of ferrous ion in the ore column. To calibrate the computational model, a column test was performed using infiltration of sulfide ferrous solution (the initial concentration is c0=0.04 mol/L) on a 100 cm high column composed of ore particles smaller than 10 mm for 2.5 h. The numerical analysis shows that the results obtained from numerical modeling under the same operating conditions as used for column test are in good agreement with those from experimental procedure on the whole trend, which indicates that the model, the numerical method, and the parameters chosen can reflect the rule of ferrous ion transmission in ore heap. 展开更多
关键词 heap leaching solute transmission dynamic experiment numerical solution
下载PDF
Digital driver for 2-inch LTPS AM-OLED displays 被引量:1
20
作者 YIN Sheng CHENG Shuai SHEN Liang ZOU Xue-cheng 《Optoelectronics Letters》 EI 2006年第2期83-85,共3页
For LTPS AM-OLED displays,the spatial variation in the electrical characteristics of polysilicon TFTs will cause non-uniform pixel brightness and poor grayscale accuracy.The technological solution for this problem wil... For LTPS AM-OLED displays,the spatial variation in the electrical characteristics of polysilicon TFTs will cause non-uniform pixel brightness and poor grayscale accuracy.The technological solution for this problem will open up the larger size application of LTPS AM-OLED displays.In this paper,a digital driver employing a FPGA device is designed to serve 2-inch color LTPS AM-OLED displays with 128×(160×3) resolution.A digital method of simultaneous address-display (SAD) and the digital visual interface (DVI) are introduced in the driving scheme.100% display per.ratio can be obtained.Moving image with 16 grayscales is realized and has good image uniformity. 展开更多
关键词 LTPS AM-OLED 显示器 多晶硅
下载PDF
上一页 1 2 9 下一页 到第
使用帮助 返回顶部