期刊文献+
共找到8,012篇文章
< 1 2 250 >
每页显示 20 50 100
Installation and Debugging of Auto-control System in Fruit Wine Production Line
1
作者 方良材 黄卫萍 陈赶林 《Agricultural Science & Technology》 CAS 2014年第4期611-615,共5页
[Objective] The aim was to test the controlling effect of cleaning steriliza- tion system, material conveying system, and fermentation jar cooling system with equip- ments of fruit wine production line introduced in t... [Objective] The aim was to test the controlling effect of cleaning steriliza- tion system, material conveying system, and fermentation jar cooling system with equip- ments of fruit wine production line introduced in this study and its auto-control sys- tem field assembled and debugged. [Method] Based on controlling equipment and setting parameters on the configuration interface, the operation state of the control equipments could be real-time monitored and controlled with the help of configura- tion software. [Result] The result showed that the equipment system could reduce the temperature into 12 ℃ with the error of +0.5 ℃within 110 minutes when the fermentation temperature is set at 12 ℃ in real production. [Conclusion] The auto- control system of fruit wine production line was easy to be assembled and de- bugged to meet demands of different fruit wine productions. 展开更多
关键词 Fruit wine production line control system INSTALLATION DEBUGGING
下载PDF
Hand-eye-vision based control for an inspection robot's autonomous line grasping 被引量:14
2
作者 王伟 吴功平 +6 位作者 白玉成 肖华 杨智勇 严宇 何缘 徐显金 苏帆 《Journal of Central South University》 SCIE EI CAS 2014年第6期2216-2227,共12页
In order to ensure that the off-line arm of a two-arm-wheel combined inspection robot can reliably grasp the line in case of autonomous obstacle crossing,a control method is proposed for line grasping based on hand-ey... In order to ensure that the off-line arm of a two-arm-wheel combined inspection robot can reliably grasp the line in case of autonomous obstacle crossing,a control method is proposed for line grasping based on hand-eye visual servo.On the basis of the transmission line's geometrical characteristics and the camera's imaging principle,a line recognition and extraction method based on structure constraint is designed.The line's intercept and inclination are defined in an imaging space to represent the robot's change of pose and a law governing the pose decoupling servo control is developed.Under the integrated consideration of the influence of light intensity and background change,noise(from the camera itself and electromagnetic field)as well as the robot's kinetic inertia on the robot's imaging quality in the course of motion and the grasping control precision,a servo controller for grasping the line of the robot's off-line arm is designed with the method of fuzzy control.An experiment is conducted on a 1:1 simulation line using an inspection robot and the robot is put into on-line operation on a real overhead transmission line,where the robot can grasp the line within 18 s in the case of autonomous obstacle-crossing.The robot's autonomous line-grasping function is realized without manual intervention and the robot can grasp the line in a precise,reliable and efficient manner,thus the need of actual operation can be satisfied. 展开更多
关键词 inspection robot line grasping control visual servo overhead transmission line autonomous obstacle-crossing
下载PDF
Dynamic Balance Control Based on an Adaptive Gain-scheduled Backstepping Scheme for Power-line Inspection Robots 被引量:6
3
作者 Songyi Dian Lin Chen +2 位作者 Son Hoang Ming Pu Junyong Liu 《IEEE/CAA Journal of Automatica Sinica》 EI CSCD 2019年第1期198-208,共11页
This paper presents an adaptive gain-scheduled backstepping control(AGSBC) scheme for the balance control of an underactuated mechanical power-line inspection(PLI) robotic system with two degrees of freedom and a sing... This paper presents an adaptive gain-scheduled backstepping control(AGSBC) scheme for the balance control of an underactuated mechanical power-line inspection(PLI) robotic system with two degrees of freedom and a single control input.First, a nonlinear dynamic model of the balance adjustment process of the PLI robot is constructed, and then the model is linearized at a nominal equilibrium point to overcome the computational infeasibility of the conventional backstepping technique. Second, to solve generalized stabilization control issue for underactuated systems with multiple equilibrium points,an equilibrium manifold linearized model is developed using a scheduling variable, and then a gain-scheduled backstepping control(GSBC) scheme for expanding the operational area of the controlled system is constructed. Finally, an adaptive mechanism is proposed to counteract the impact of external disturbances. The robust stability of the closed-loop system is ensured by Lyapunov theorem. Simulation results demonstrate the effectiveness and high performance of the proposed scheme compared with other control schemes. 展开更多
关键词 Adaptive BACKSTEPPING BALANCE control gain-scheduled inspection robot POWER line
下载PDF
Steady-state voltage-control method considering large-scale wind-power transmission using half-wavelength transmission lines 被引量:3
4
作者 Hao Tian Hongzheng Liu +3 位作者 Huan Ma Pengfei Zhang Xiaohui Qin Changhui Ma 《Global Energy Interconnection》 EI CAS CSCD 2021年第3期239-250,共12页
Half-wavelength transmission can transmit large-scale renewable energy over very long distances.This paper proposes an improved steady-state voltage-control method for half-wavelength transmission systems considering ... Half-wavelength transmission can transmit large-scale renewable energy over very long distances.This paper proposes an improved steady-state voltage-control method for half-wavelength transmission systems considering largescale wind-power transmission.First,the unique voltage characteristics of half-wavelength lines are deduced based on the distributed parameter model.In the secondary voltage-control level,reactive power-transmission limits of half-wavelength lines are introduced as another control objective except for tracing the pilot bus voltage reference.Considering the uncertainty and fluctuation of wind power,the overvoltage risk-assessment method of half-wavelength lines is presented to determine specific voltage-control strategies.Simulation results demonstrate that the proposed voltage-control method delivers superior tracking performance according to a voltage reference value and prevents the overvoltage risk of halfwavelength lines effectively in different wind-power penetrations. 展开更多
关键词 Half-wavelength lines Secondary voltage control Wind-power transmission Reactive power regulation
下载PDF
Stabilization of CSTR w ith Self-tuning Sliding Mode Controller Using T-S Fuzzy Linearization 被引量:2
5
作者 朱群雄 王军霞 《Journal of Donghua University(English Edition)》 EI CAS 2013年第4期287-292,共6页
A self-tuning reaching law based sliding mode control(SMC)theory is proposed to stabilize the nonlinear continuous stirred tank reactor(CSTR).T-S fuzzy logic is used to build a global fuzzy state-space linear model.Co... A self-tuning reaching law based sliding mode control(SMC)theory is proposed to stabilize the nonlinear continuous stirred tank reactor(CSTR).T-S fuzzy logic is used to build a global fuzzy state-space linear model.Combing the traits of SMC and CSTR,three fuzzy rules can meet the requirements of controlled system.The self-tuning switch control law which can drive the state variables to the sliding surface as soon as possible is designed to ensure the robustness of uncertain fuzzy system.Lyapunov equation is applied to proving the stability of the sliding surface.The simulations show that the proposed approach can achieve desired performance with less chattering problem. 展开更多
关键词 sliding mode control(SMC) continuous stirred tank reactor (STR) T-S fuzzy model self-tuning switch control lawCLC number:TP13Document code:AArticle ID:1672-5220(2013)04-0287-06
下载PDF
Frame Design and Reality of On-line Quality Control System for CNC Machining Center Based on Microcomputer
6
作者 刘晓胜 《High Technology Letters》 EI CAS 1998年第2期26-32,共7页
After giving a short review of the methods used for detecting and monitoring in general systems, this paper describes the way of communication between computer and Computer Numerical Control (CNC) Machining Center (MC... After giving a short review of the methods used for detecting and monitoring in general systems, this paper describes the way of communication between computer and Computer Numerical Control (CNC) Machining Center (MC). Based on these, the paper addresses the means of performing in cycle measurement for manufacturing quality, provides an approach of improving the state of manufacturing process by achieving the real time change of control parameters according to the level of manufacturing process, and discusses the technique of implementing in process dimensional errors compensation corresponding to the in cycle measurement. The results of the experiments show that the frame design is successful and the operation is reliable. The system is taking shape nowadays. 展开更多
关键词 Detection MONITOR Compensation In cycle measurement On line QUALITY control Manufacturing process
下载PDF
Self-adaptive PID controller of microwave drying rotary device tuning on-line by genetic algorithms 被引量:6
7
作者 杨彪 梁贵安 +5 位作者 彭金辉 郭胜惠 李玮 张世敏 李英伟 白松 《Journal of Central South University》 SCIE EI CAS 2013年第10期2685-2692,共8页
The control design, based on self-adaptive PID with genetic algorithms(GA) tuning on-line was investigated, for the temperature control of industrial microwave drying rotary device with the multi-layer(IMDRDWM) and wi... The control design, based on self-adaptive PID with genetic algorithms(GA) tuning on-line was investigated, for the temperature control of industrial microwave drying rotary device with the multi-layer(IMDRDWM) and with multivariable nonlinear interaction of microwave and materials. The conventional PID control strategy incorporated with optimization GA was put forward to maintain the optimum drying temperature in order to keep the moisture content below 1%, whose adaptation ability included the cost function of optimization GA according to the output change. Simulations on five different industrial process models and practical temperature process control system for selenium-enriched slag drying intensively by using IMDRDWM were carried out systematically, indicating the reliability and effectiveness of control design. The parameters of proposed control design are all on-line implemented without iterative predictive calculations, and the closed-loop system stability is guaranteed, which makes the developed scheme simpler in its synthesis and application, providing the practical guidelines for the control implementation and the parameter design. 展开更多
关键词 industrial microwave DRYING ROTARY device SELF-ADAPTIVE PID controller genetic algorithm ON-line tuning SELENIUM-ENRICHED SLAG
下载PDF
Modeling of Microstructure Evolution and Mechanical Properties of Steel Plates Produced by Thermo-Mechanical Control Process and Its On-line Application 被引量:1
8
作者 Yunbo XU, Yongmei YU, Xianghua LIU and Guodong WANGState Key Laboratory of Rolling Technology and Automation, Northeastern University, P.O. Box 105, Shenyang 110004, ChinaPh.D., 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2005年第1期13-16,共4页
An integrated metallurgical model was developed to predict microstructure evolution and mechanical properties of low-carbon steel plates produced by TMCP. The metallurgical phenomena occurring during TMCP and mechanic... An integrated metallurgical model was developed to predict microstructure evolution and mechanical properties of low-carbon steel plates produced by TMCP. The metallurgical phenomena occurring during TMCP and mechanical properties were predicted for different process parameters. In the later passes full recrystallization becomes difficult to occur and higher residual strain remains in austenite after rolling. For the reasonable temperature and cooling schedule, yield strength of 30 mm plain carbon steel plate can reach 310 MPa. The first on-line application of prediction and control of microstructure and properties (PCMP) in the medium plate production was achieved. The predictions of the system are in good agreement with measurements. 展开更多
关键词 Thermo-mechanical control process Metallurgical model Low-carbon steel Prediction and control of microstructure and properties On-line application
下载PDF
An on-line data acquisition system of oscilloscope-embedded input/output controller for cavity BPM measurement 被引量:1
9
作者 ZHANG Ning WANG Baopeng LENG Yongbin 《Nuclear Science and Techniques》 SCIE CAS CSCD 2011年第6期321-325,共5页
Cavity beam position monitor(BPM) is widely used in a precise electron beam position measurement. Based on high performance oscilloscope-embedded EPICS input/output controller,we developed an on-line cavity BPM signal... Cavity beam position monitor(BPM) is widely used in a precise electron beam position measurement. Based on high performance oscilloscope-embedded EPICS input/output controller,we developed an on-line cavity BPM signal processing system for fast data acquisition solution when designing a cavity BPM.Also,methods for extracting the position information from cavity pickup signals and calibration algorithm are included in this solution. 展开更多
关键词 嵌入式控制器 数据采集系统 输入/输出 位置测量 BPM 示波器 信号处理系统 束流位置
下载PDF
Small unmanned helicopter's attitude controller by an on-line adaptive fuzzy control system
10
作者 GAO Tong-yue RAO Jin-jun GONG Zhen-bang LUO Jun 《重庆邮电大学学报(自然科学版)》 北大核心 2009年第2期148-153,共6页
Since small unmanned helicopter flight attitude control process has strong time-varying characteristics and there are random disturbances,the conventional control methods with unchanged parameters are often unworkable... Since small unmanned helicopter flight attitude control process has strong time-varying characteristics and there are random disturbances,the conventional control methods with unchanged parameters are often unworkable.An on-line adaptive fuzzy control system(AFCS)was designed,in a way that does not depend on a process model of the plant or its approximation in the form of a Jacobian matrix.Neither is it necessary to know the desired response at each instant of time.AFCS implement a simultaneous on-line tuning of fuzzy rules and output scale of fuzzy control system.The two cascade controller design with an inner(attitude controller)and outer controller(navigation controller)of the small unmanned helicopter was proposed.At last,an attitude controller based on AFCS was implemented.The flight experiment showed that the proposed fuzzy logic controller provides quicker response,smaller overshoot,higher precision,robustness and adaptive ability.It satisfies the needs of autonomous flight. 展开更多
关键词 自适应模糊控制系统 无人驾驶直升机 模糊控制器 在线调整 时间变化 雅可比矩阵 自适应能力 随机干扰
下载PDF
Investigation and Analysis of the Status Quo of Prevention and Control Practices of Catheter-Line Associated Bloodstream Infections (CLABSI) in Guangxi, China 被引量:1
11
作者 Caijiao Wu Huihan Zhao +3 位作者 Galal A. Al-Samhari Qingjuan Jiang Ying Ling Yanping Ying 《Advances in Infectious Diseases》 2021年第4期333-343,共11页
The prevention and control of catheter line-associated bloodstream infections (CLABSI) have become the key content of medical care and have become the core improvement goal of nursing quality control. However, the pre... The prevention and control of catheter line-associated bloodstream infections (CLABSI) have become the key content of medical care and have become the core improvement goal of nursing quality control. However, the prevention and control status of CLABSI in hospitals of different grades in Guangxi is not clear. In this study, we aim to investigate central venous catheter (CVC) placement and disinfectant use in second and third-level hospitals in Guangxi. This survey was conducted on the second and third-level hospitals in Guangxi, China from 13th April 2021 to 19th April 2021. The results show that a total of 283 questionnaires were collected, including 206 secondary hospitals and 77 tertiary hospitals. In terms of the CVC, tertiary hospitals were able to place CVC entirely under the guidance of B-ultrasound, which was 24 (31.6%) and secondary hospitals were 26 (20.6%). In secondary hospitals, Most CVC placements were performed in operating rooms 94 (74.6%) and 65 (85.5%) on the third level hospital, but 32.5% of secondary hospitals and 48.7% of tertiary hospitals were selected at the bedside of patients in general wards, and 27.8% of the second-level hospital, 43.4% of third-level hospitals was done in general ward treatment rooms, only 61.9% of secondary hospitals and 64.5% of tertiary hospitals could fully achieve the maximum sterile barrier. In terms of skin disinfectants, only 36.0% of tertiary hospitals and 16.4% of second-level CVC-operators chose > 0.5% chlorhexidine alcohol. In conclusion, the prevention and control of catheter line-associated bloodstream infections (CLABSI) in Guangxi are not ideal. The prevention and control department should increase training, implement guidelines and standardize management to reduce the incidence of CLABSI. 展开更多
关键词 Central Venous Catheter Catheter-line Associated Bloodstream Infections PREVENTION Quality control Survey
下载PDF
On-line current feed and computer aided control tactics for automatic balancing head
12
作者 李勇 陆永平 +1 位作者 须根发 夏松波 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2002年第2期205-207,共3页
In the designed automatic balancing head, a non contact induction transformer is used to deliver driving energy to solve the problem of current fed and controlling on line. Computer controlled automatic balancing expe... In the designed automatic balancing head, a non contact induction transformer is used to deliver driving energy to solve the problem of current fed and controlling on line. Computer controlled automatic balancing experiments with phase magnitude control tactics were performed on a flexible rotor system. Results of the experiments prove that the energy feeding method and the control tactics are effective in the automatic balancing head for vibration controlling. 展开更多
关键词 AUTOMATIC balancing balancing HEAD ON-line control TACTICS
下载PDF
Design of in-line multipoint initiation control system
13
作者 李守殿 袁士伟 曾庆轩 《Journal of Beijing Institute of Technology》 EI CAS 2011年第3期306-311,共6页
In order to improve the power of initiating explosive warheads, besides exploring new type of high explosive, multipoint initiation technology becomes the research focus. With research on electronic safety and arming ... In order to improve the power of initiating explosive warheads, besides exploring new type of high explosive, multipoint initiation technology becomes the research focus. With research on electronic safety and arming devices (ESADs), pulse power devices and slapper detonators, a hardware control circuit was designed for multipoint initiation control system based on complex programmable logic device ( CPLD ). In addition, a real-time monitoring interface based on virtual instru- ments technology was designed by the prevailing software of Laboratory Virtual Instrument Engineer- ing Workbench (LabVIEW). It provides users a real-time status of the hardware circuit system. Mo- reover, a series of experiments were done on the software and hardware platform. The results show that the signals transmission, collection, analysis and display can be realized reliably through a serial port line. It is verified that using a serial bus controller for multiple initiators is reasonable. Successful design of the platform will play an important foundation for the theory and engineering of the fu- ture weapon system. Surely, it will become one of the development directions for intelligent initia- tion system. 展开更多
关键词 multipoint initiation control system IN-line electronic safety and arming virtual instrument
下载PDF
Application of on-line quality control for salvianolic acid B by near infrared spectroscopy
14
作者 Jin-Wei Zhang Yan Liu +1 位作者 Wei-Wei Liu Yan-Ying Zhang 《Health》 2009年第3期244-248,共5页
OBJECTIVE: To study and establish quality con-trol model of the Salvianolic Acid B by Near In-frared Spectroscopy (NIRS), and to realize on-line quality control of extracting and purifying proc-esses of industrial sca... OBJECTIVE: To study and establish quality con-trol model of the Salvianolic Acid B by Near In-frared Spectroscopy (NIRS), and to realize on-line quality control of extracting and purifying proc-esses of industrial scale herbal product manu-facturing. METHOD: NIR chromatography was obtained from on-line NIR detection of extract-ing process and purifying process. HPLC analysis was carried out to determine the con-tents of salvianolic acid B. Partial Least Squares Regression (PLS) was used to establish the model between the information between NIRS and HPLC. RESULTS: For extracting model: the optimum Near Infrared (NIR) wavelength range was 9815- 5430cm-1, R=0.9784, RMSEC=0.258;for puri-fying model: the optimum NIR wavelength range was 9815-5430cm-1, R=0.9776, RMSEC=4.02. The average relative error was <5%. CONCLUSION: NIR technique is applicable for on-line quality control in production of salvianolic acid B. 展开更多
关键词 NIR Salvianolic ACID B ON-line QUALITY control INDUSTRIAL SCALE
下载PDF
逆转座子LINE-1在基因组中的调控作用 被引量:1
15
作者 朱运峰 李冠琳 《中国农业科技导报》 CAS CSCD 北大核心 2012年第4期13-23,共11页
近年来研究发现真核生物基因组中的许多重复序列以及基因的内含子参与基因表达的调控。在这些重复序列中,有一种广泛分布于基因组中的逆转座子LINE-1,目前发现其对细胞的增殖与分化以及肿瘤的发生起着非常重要的作用,具体表现为影响基... 近年来研究发现真核生物基因组中的许多重复序列以及基因的内含子参与基因表达的调控。在这些重复序列中,有一种广泛分布于基因组中的逆转座子LINE-1,目前发现其对细胞的增殖与分化以及肿瘤的发生起着非常重要的作用,具体表现为影响基因的转录及整个基因组的稳定性、参与X染色体失活及基因组进化等。在正常细胞的分化调控中,基因的激活与沉默具有时间与空间的特异性,实现其"预定"的、有序的、不可逆转的分化过程。主要阐述了逆转座子LINE-1的结构特征和其在基因组中的调控作用及这些作用影响基因表达从而调节生物体的生命活动。研究LINE-1的调控机制对认识细胞的时空调控以及癌症的发生与发展具有重要的价值。 展开更多
关键词 基因表达调控 line-1逆转座子 细胞增殖分化 癌症
下载PDF
Evaluation of Two Momentum Control Variable Schemes and Their Impact on the Variational Assimilation of Radar Wind Data:Case Study of a Squall Line 被引量:10
16
作者 Xin LI Mingjian ZENG +3 位作者 Yuan WANG Wenlan WANG Haiying WU Haixia MEI 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2016年第10期1143-1157,共15页
Different choices of control variables in variational assimilation can bring about different influences on the analyzed atmospheric state. Based on the WRF model's three-dimensional variational assimilation system, t... Different choices of control variables in variational assimilation can bring about different influences on the analyzed atmospheric state. Based on the WRF model's three-dimensional variational assimilation system, this study compares the be- havior of two momentum control variable options-streamfunction velocity potential (ψ-χ) and horizontal wind components (U-V)-in radar wind data assimilation for a squall line case that occurred in Jiangsu Province on 24 August 2014. The wind increment from the single observation test shows that the ψ-χ control variable scheme produces negative increments in the neighborhood around the observation point because streamfunction and velocity potential preserve integrals of velocity. On the contrary, the U-V control variable scheme objectively reflects the information of the observation itself. Furthermore, radial velocity data from 17 Doppler radars in eastern China are assimilated. As compared to the impact of conventional observation, the assimilation of radar radial velocity based on the U-V control variable scheme significantly improves the mesoscale dynamic field in the initial condition. The enhanced low-level jet stream, water vapor convergence and low-level wind shear result in better squall line forecasting. However, the ψ-χ control variable scheme generates a discontinuous wind field and unrealistic convergence/divergence in the analyzed field, which lead to a degraded precipitation forecast. 展开更多
关键词 three-dimensional variational assimilation momentum control variable Doppler radar data squall line
下载PDF
Where is the rudder of a fish?:the mechanism of swimming and control of self-propelled fish school 被引量:14
17
作者 Chuijie Wu Liang Wang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2010年第1期45-65,共21页
Numerical simulation and control of self- propelled swimming of two- and three-dimensional biomimetic fish school in a viscous flow are investigated. With a parallel computational fluid dynamics package for the two- a... Numerical simulation and control of self- propelled swimming of two- and three-dimensional biomimetic fish school in a viscous flow are investigated. With a parallel computational fluid dynamics package for the two- and three-dimensional moving boundary problem, which combines the adaptive multi-grid finite volume method and the methods of immersed boundary and volume of fluid, it is found that due to the interactions of vortices in the wakes, without proper control, a fish school swim with a given flap- ping rule can not keep the fixed shape of a queue. In order to understand the secret of fish swimming, a new feedback con- trol strategy of fish motion is proposed for the first time, i,e., the locomotion speed is adjusted by the flapping frequency of the caudal, and the direction of swimming is controlled by the swinging of the head of a fish. Results show that with this feedback control strategy, a fish school can keep the good order of a queue in cruising, turning or swimming around circles. This new control strategy, which separates the speed control and direction control, is important in the construction of biomimetic robot fish, with which it greatly simplifies the control devices of a biomimetic robot fish. 展开更多
关键词 Self-propelled swimming Feedback controlstrategy of fish swimming ~ Direction control - Locomotionspeed control Three-dimensional biomimetic fish
下载PDF
Dynamics and adaptive control of a dual-arm space robot with closed-loop constraints and uncertain inertial parameters 被引量:20
18
作者 Ying-Hong Jia Quan Hu Shi-Jie Xu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2014年第1期112-124,共13页
A dynamics-based adaptive control approach is proposed for a planar dual-arm space robot in the presence of closed-loop constraints and uncertain inertial parameters of the payload. The controller is capable of contro... A dynamics-based adaptive control approach is proposed for a planar dual-arm space robot in the presence of closed-loop constraints and uncertain inertial parameters of the payload. The controller is capable of controlling the po- sition and attitude of both the satellite base and the payload grasped by the manipulator end effectors. The equations of motion in reduced-order form for the constrained system are derived by incorporating the constraint equations in terms of accelerations into Kane's equations of the unconstrained system. Model analysis shows that the resulting equations perfectly meet the requirement of adaptive controller design. Consequently, by using an indirect approach, an adaptive control scheme is proposed to accomplish position/attitude trajectory tracking control with the uncertain parameters be- ing estimated on-line. The actuator redundancy due to the closed-loop constraints is utilized to minimize a weighted norm of the joint torques. Global asymptotic stability is proven by using Lyapunov's method, and simulation results are also presented to demonstrate the effectiveness of the proposed approach. 展开更多
关键词 Space robot Dynamics. Adaptive control Closed-loop constraint Parameter uncertainty - Kane's equation
下载PDF
Deformation behaviors of 21-6-9 stainless steel tube numerical control bending under different friction conditions 被引量:9
19
作者 方军 鲁世强 +1 位作者 王克鲁 姚正军 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第8期2864-2874,共11页
For contact dominated numerical control(NC) bending process of tube, the effect of friction on bending deformation behaviors should be focused on to achieve precision bending forming. A three dimensional(3D) elastic-p... For contact dominated numerical control(NC) bending process of tube, the effect of friction on bending deformation behaviors should be focused on to achieve precision bending forming. A three dimensional(3D) elastic-plastic finite element(FE) model of NC bending process was established under ABAQUS/Explicit platform, and its reliability was validated by the experiment. Then, numerical study on bending deformation behaviors under different frictions between tube and various dies was explored from multiple aspects such as wrinkling, wall thickness change and cross section deformation. The results show that the large friction of wiper die-tube reduces the wrinkling wave ratio η and cross section deformation degree ΔD and increases the wall thinning degree Δt. The large friction of mandrel-tube causes large η, Δt and ΔD, and the onset of wrinkling near clamp die. The large friction of pressure die-tube reduces Δt and ΔD, and the friction on this interface has little effect on η. The large friction of bending die-tube reduces η and ΔD, and the friction on this interface has little effect on Δt. The reasonable friction coefficients on wiper die-tube, mandrel-tube, pressure die-tube and bending die-tube of 21-6-9(0Cr21Ni6Mn9N) stainless steel tube in NC bending are 0.05-0.15, 0.05-0.15, 0.25-0.35 and 0.25-0.35, respectively. The results can provide a guideline for applying the friction conditions to establish the robust bending environment for stable and precise bending deformation of tube bending. 展开更多
关键词 21-6-9 stainless steel tube FRICTION deformation behaviors numerical control bending finite element simulation
下载PDF
ACOUSTICAL TRANSMISSION LINE MODEL FOR ULTRASONIC TRANSDUCERS FOR WIDE-BANDWIDTH APPLICATION 被引量:1
20
作者 Yeongchin Chen 《Acta Mechanica Solida Sinica》 SCIE EI 2010年第2期124-134,共11页
An improved model for ultrasonic transducers is proposed. By considering only the first symmetric mode, each layer is represented as an acoustical transmission line in modeling of bulk wave transducers. In imaging app... An improved model for ultrasonic transducers is proposed. By considering only the first symmetric mode, each layer is represented as an acoustical transmission line in modeling of bulk wave transducers. In imaging applications, wide bandwidth and short time duration are required. The approach we have used consists of impedance matching the front face of the piezoelectric transducer to the propagating medium with a quarter wavelength impedance matching layer and inserting an nnmatching quarter wavelength acoustical layer between the rear face and backing material. A heavy backing would degrade the wide-band phenomena, but show a time duration shorter than 0.5 μs for imaging applications. PSPICE code of the controlled source model is implemented to precisely predict the performance of the matched transducers such as impedance, insertion loss, bandwidth and duration of the impulse response. Good agreement between the simulation and experimental results has been achieved. 展开更多
关键词 acoustical transmission line ultrasonic transducer wide-bandwidth PSPICE controlled source
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部