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Nonlinear Dynamic Characteristics of the Vectored Thruster AUV in Complex Sea Conditions 总被引:1,自引:0,他引:1
GAO Fudong PAN Cunyun XU Xiaojun ZHANG Xiang College of Mechatronic Engineering Automation National University of Defense Technology Changsha China Received November revised June accepted July published electronically July 《机械工程学报(英文版)》2011,(6):935-946
The mobility of the vectored thruster AUV in different environment is the important premise of control system design. The new type of autonomous underwater vehicle (AUV) equipped with rudders and vectored thrusters which are combined to control the course is studied. Firstly, Euler angles representation and quaternion method are applied to establish six-DOF kinematic model respectively, then Newton second law and Lagrangian approach are used to deduce the vectored thruster AUV’s nonlinear dynamic equations with six degrees of freedom (DOF) respectively in complex sea conditions based on the random wave theory according to the structural and kinetic characteristics of the vectored thruster AUV in this paper. The kinematic models and dynamic models based on different theories have the same expression and conclusion, which shows that the kinematic models and dynamic models of the vectored thruster AUV are accurate. The Runge-Kutta arithmetic is used to solve the dynamic equations, which not only can simulate the motions such as cruise and hover but also can describe the vehicle’s low-frequency and high-frequency motion. The results of computation show that the mobility of the vectored thruster AUV in interference-free environment and the integrated signals including low-frequency motion signal and high-frequency motion signal in environmental disturbance accord with practical situation, which not only solve the problem of especial singularities when the pitch angle θ = ±90° but also clears up the difficulties of computation and display of the coupled nonlinear motion equations in complex sea conditions. Moreover, the high maneuverability of the vectored thruster AUV equipped with rudders and vectored thrusters is validated, which lays a foundation for the control system design. 相似文献
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Micro/nano Indentation and Single Grit Diamond Grinding Mechanism on Ultra Pure Fused Silica 总被引:1,自引:0,他引:1
ZHAO Qingliang GUO Bing STEPHENSIN David CORBETT John School of Mechatronics Engineering Harbin Institute of Technology Harbin China Materials Department Cranfield University Cranfield Bedford MK AL UK School of Applied Sciences UK Received February revised November accepted February published electronically November 《机械工程学报(英文版)》2011,(6)
The existing research about ductile grinding of fused silica glass was mainly focused on how to carry out ductile regime material removal for generating very smoothed surface and investigate the machining-induced damage in the grinding in order to reduce or eliminate the subsurface damage.The brittle/ductile transition behavior of optical glass materials and the wear of diamond wheel are the most important factors for ductile grinding of optical glass.In this paper,the critical brittle/ductile depth,the inf... 相似文献
34.
SONG Wanqing ZHANG Jing College of Electronic Electrical Engineering Shanghai University of Engineering Science Shanghai China Received March revised March accepted May published electronically November 《机械工程学报(英文版)》2011,(6):1068-1073
It is a fact that acoustic emission(AE) signals contain potentially valuable information for tool wear and breakage monitoring and detection.However,AE stress waves produced in the cutting zone are distorted by the transmission path and the measurement systems,it is difficult to obtain a reliable result by these raw AE data.It is generally known that the process of tool wear belongs to detect weak singularity signals in strong noise.The objective of this paper is to combine Newland Harmonic wavelet and Richman-Moorman(2000) sample entropy for detecting weak singularity signals embedded in strong signals.First,the raw AE signal is decomposed by harmonic wavelet and transformed into the three-dimensional time-frequency mesh map of the harmonic wavelet,at the same time,the contours of the mesh map with log space is induced.Second,the profile map of the three-dimensional time-frequency mesh map is offered,which corresponds to decomposed level on harmonic wavelets.Final,by computing sample entropy in each level,the weak singularity signal can be easily extracted from strong noise.Machining test was carried out on HL-32 NC turning center.This lathe does not have a tailstock.Tungsten carbide finishing tool was used to turn free machining mild steel.The work material was chosen for ease of machining,allowing for generation of surfaces of varying quality without the use of cutting fluids.In turning experiments,the feasibility for tool condition monitoring is demonstrated by 27 kinds of cutting conditions with the sharp tool and the worn tool,54 group data are sampled by AE.The sample entropy of each level of wavelet decomposed for each one of 54 AE datum is computed,wear tool and shaper tool can be distinguished obviously by the sample entropy value at the 12th level,this is a criterion.The proposed research provides a new theoretical basis and a new engineering application on the tool condition monitoring. 相似文献
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ZENG Xianghui QI Lehua HUANG Hua LI Yang YANG Fang School of Mechatronics Northwestern Polytechnical University Xi'an China Key Laboratory of Modern Design Integrated Manufacturing Technology of Ministry of Education China Received March revised January accepted June published electronically November 《机械工程学报(英文版)》2011,(6):1083-1088
Ultrasonic vibration feeding(UVF) method which can quantitatively feed and precisely deposit fine powder is a potential technique for micro feeding.The excitation sources transmit vibration to capillary though the third medium for most UVF devices.The vibrator is directly touched with the capillary can transmit mechanical energy on the capillary as much as possible,and the powder feeding can be controlled more precise.However,there are few reports about it.A direct UVF system which integrates the function of micro feeding,process observing,and powder forming was developed in this work.In order to analyze the effect of the system factors on feeding,a group of L9(33) orthogonal experiments are selected to confirm the effect of level change of factors.The three factors are capillary nozzle diameter,amplitude and signal.The flow rate was stable for each combined factors,and the optimum combination for the minimum flow rate are choosing small capillary,small amplitude,and triangular wave orderly.The whole process of feeding includes start point,middle stage and stop stage.Starting of feeding was synchronized to vibration when the amplitude of capillary nozzle is larger than critical amplitude.Then,the feeding process enters the middle stage,the feeding state is observed by the CCD,and it is very stable in the middle stage.Overflow of feeding can’t be eliminated during the stop stage.The features of the deposited powder lines are analyzed;the overflow can be diminished by choosing small capillary and appropriate ratio of the capillary nozzle diameter to the particle size.Chinese characters lattices were deposited to validate the ability of quantitatively feeding and fixed feeding of UVF.Diameters of all powder dots show normal distribution,and more than 60% dots are concentrated from 550 μm to 650 μm,and the average diameter for all the dots is 597 μm.Most dots positions are well approached to their scheduled positions,and the maximum deviation is 0.27 mm.The new direct UVF system is used to implement experiments,which confirms the precise controllable of feeding.According improve the feeding technique,it suits well for rapid prototyping,chemistry,pharmaceutics and many other fields,which require precise measurement and feed minim powder. 相似文献
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JIN Jiamei WANG Yin YANG Ying ZHANG Jianhui State Key Laboratory of Mechanics Control of Mechanical Structures Nanjing University of Aeronautics Astronautics Nanjing China Received September revised October accepted October published electronically October 《机械工程学报(英文版)》2011,(6):1130-1135
There are two kinds of piezoelectric pumps:check valve pumps and valve-less pumps.Whether to use a check valve or not depends upon the application occasion.To achieve large backpressure for higher flow rates,the pump with check valve is desirable.However,adding check valves implies more complex structure and higher probability of valve blocking,etc.In order to solve the problem,effective driving and transport mechanics with compact construction and reliable service are being sought.In this paper,using the second-order longitudinal vibration mode of a bar-shaped piezoelectric vibrator for driving fluid,a piezoelectric pump is successfully made.The proposed piezoelectric pump consists of coaxial cylindrical shells and a bar-shaped piezoelectric vibrator,which has a disk part and a cone part.The lead zirconium titanate ceramic rings fixed in the vibrator are polarized along the thickness direction.When the second-order longitudinal vibration of the vibrator along its axis is excited,the disk part of the vibrator changes periodically the volume of the chamber and the cone part acts as a pin valve,driving the fluid from the inlet port to the outlet port.Finite elements analysis on the proposed pump model is carried out to verify its operation principle and design by the commercial FEM software ANSYS.Components of the piezoelectric pump were manufactured,assembled,and tested for flow rate and backpressure to validate the concepts of the proposed pump and confirm the simulation results of modal and harmonic analyses.The test results show that the performance of the proposed piezoelectric pump is about 910 mL/min in flow rate with a highest pressure level of 1.5 kPa under 400 V peak-to-peak voltage and 51.7 kHz operating frequency.It is confirmed that this bar-shaped piezoelectric transducer can be effectively applied in fluid transferring mechanism of pump through this research. 相似文献
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EFFECTOFCARBIDESOLVATIONONFERRITEFORMATIONINAUSTENITICSTEELSDAIQixunandYANGRuzeng(DepartmentofMaterialsScienceandEngineering,... 相似文献
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Cu—Ni合金组元的偏原子体积与平均原子体积的关系 总被引:1,自引:0,他引:1
本文建立了固溶体组元的偏摩尔性质与平均摩尔性质的一般关系式手CC理论中的偏摩尔性质函数;导出了组元的偏摩尔性质与平均摩尔性质的差值方程和差值约束方程,以及Gibbs-Duhem一般式;证明由CC理论中固溶体平均摩尔性质各组合函数求得的偏摩尔性质是相等的,但在一般情况下,偏摩尔性质不等于组元的平均摩尔性质。以Cu-Ni合金和组元的平均原子体积以及组元的偏原子体积的计算为例,证明了这些论述。 相似文献
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MICROSTRUCTURES AND PROPERTIES OF DZ40M Co-BASE SUPERALLOY AFTER LONG-TERM AGEING AT 950℃ 总被引:5,自引:0,他引:5
研究了新近开发的一种定向凝固钴基高温合金DZ40M950℃长期时效后的组织与性能。结果表明,合金时效后室温强度提高,塑性降低,980℃,83MPa持久性能提高,而816℃,215MPa持久性能下降,在时效过程中,初生碳化物M7C3和MC缓慢分解,细小的M23C6在基体中大量析出,M6C在一些M7C3表面生成。分析认为,合金性能变化主要归因于M23C6沉淀析出,初生碳化物M7C3和MC分解,释放出碳 相似文献
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STUDYONFATIGUEDAMAGEBELOWTHEFATIGUELIMITANDTHECOAXINGEFFECTSWUZhixue;LUWengeandXUHao1)(FushunPetroleuminstitute,Fushun113001,... 相似文献