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浅谈校核验算红线桩和水准点
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作者 曹万顺 《现代电力》 1991年第1期33-37,共5页
简单介绍校核验算红线柱和水准点的重要性,比较详细叙述怎样验算红线桩,并借助 EL—5100S计算器编写程序,使验算过程大为简便。
关键词 红线桩 水准点 闭台导线 EL—5100S 算计器
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Time-domain CFD computation and analysis of acoustic attenuation performance of water-filled silencers 被引量:3
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作者 LIU Chen JI Zhen-lin +1 位作者 CHENG Yin-zhong LIUSheng-lan 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第9期2397-2401,共5页
The multi-dimensional time-domain computational fluid dynamics(CFD) approach is extended to calculate the acoustic attenuation performance of water-filled piping silencers. Transmission loss predictions from the time-... The multi-dimensional time-domain computational fluid dynamics(CFD) approach is extended to calculate the acoustic attenuation performance of water-filled piping silencers. Transmission loss predictions from the time-domain CFD approach and the frequency-domain finite element method(FEM) agree well with each other for the dual expansion chamber silencer, straight-through and cross-flow perforated tube silencers without flow. Then, the time-domain CFD approach is used to investigate the effect of flow on the acoustic attenuation characteristics of perforated tube silencers. The numerical predictions demonstrate that the mean flow increases the transmission loss, especially at higher frequencies, and shifts the transmission loss curve to lower frequencies. 展开更多
关键词 water-filled silencer acoustic attenuation performance time-domain CFD approach flow effect perforated tube
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Numerical computation and analysis of unsteady viscous flow around autonomous underwater vehicle with propellers based on sliding mesh 被引量:4
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作者 高富东 潘存云 韩艳艳 《Journal of Central South University》 SCIE EI CAS 2012年第4期944-952,共9页
The flexible transmission shaft and wheel propeller are combined as the kinetic source equipment, which realizes the nmlti-motion modes of the autonomous underwater vehicle (AUV) such as vectored thruster and wheele... The flexible transmission shaft and wheel propeller are combined as the kinetic source equipment, which realizes the nmlti-motion modes of the autonomous underwater vehicle (AUV) such as vectored thruster and wheeled movement. In order to study the interactional principle between the hull and the wheel propellers while the AUV navigating in water, the computational fluid dynamics (CFD) method is used to simulate numerically the unsteady viscous flow around AUV with propellers by using the Reynolds-averaged Navier-Stokes (RANS) equations, shear-stress transport (SST) k-w model and pressure with splitting of operators (PISO) algorithm based on sliding mesh. The hydrodynamic parameters of AUV with propellers such as resistance, pressure and velocity are got, which reflect well the real ambient flow field of AUV with propellers. Then, the semi-implicit method for pressure-linked equations (SIMPLE) algorithm is used to compute the steady viscous flow field of AUV hull and propellers, respectively. The computational results agree well with the experimental data, which shows that the numerical method has good accuracy in the prediction of hydrodynamic performance. The interaction between AUV hull and wheel propellers is predicted qualitatively and quantitatively by comparing the hydrodynamic parameters such as resistance, pressure and velocity with those from integral computation and partial computation of the viscous flow around AUV with propellers, which provides an effective reference to the shady on noise and vibration of AUV hull and propellers in real environment. It also provides technical support for the design of new AUVs. 展开更多
关键词 computational fluid dynamics sliding mesh wheel propeller autonomous underwater vehicle viscous flow field
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Numerical computation and analysis of high-speed autonomous underwater vehicle (AUV) moving in head sea based on dynamic mesh 被引量:2
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作者 高富东 潘存云 +1 位作者 徐小军 韩艳艳 《Journal of Central South University》 SCIE EI CAS 2012年第11期3084-3093,共10页
Autonomous underwater vehicles (AUVs) navigating on the sea surface are usually required to complete the communication tasks in complex sea conditions. The movement forms and flow field characteristics of a multi-mo... Autonomous underwater vehicles (AUVs) navigating on the sea surface are usually required to complete the communication tasks in complex sea conditions. The movement forms and flow field characteristics of a multi-moving state AUV navigating in head sea at high speed were studied. The mathematical model on longitudinal motion of the high-speed AUV in head sea was established with considering the hydrodynamic lift based on strip theory, which was solved to get the heave and pitch of the AUV by Gaussian elimination method. Based on this, computational fluid dynamics (CFD) method was used to establish the mathematical model of the unsteady viscous flow around the AUV with considering free surface effort by using the Reynolds-averaged Navier-Stokes (RANS) equations, shear-stress transport (SST) k-w model and volume of fluid (VOF) model. The three-dimensional numerical wave in the computational field was realized through defining the unsteady inlet boundary condition. The motion forms of the AUV navigating in head sea at high speed were carried out by the program source code of user-defined function (UDF) based on dynamic mesh. The hydrodynamic parameters of the AUV such as drag, lift, pitch torque, velocity, pressure and wave profile were got, which reflect well the real ambient flow field of the AUV navigating in head sea at high speed. The computational wave profile agrees well with the experimental phenomenon of a wave-piercing surface vehicle. The force law of the AUV under the impacts of waves was analyzed qualitatively and quantitatively, which provides an effective theoretical guidance and technical support for the dynamics research and shape design of the AUV in real complex environnaent. 展开更多
关键词 computational fluid dynamics dynamic mesh autonomous underwater vehicle (AUV) MOTION head sea viscous flowfield
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Energy efficiency enhancement of two-way amplifier forward relaying with channel estimation error 被引量:1
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作者 师晓晔 葛建华 +1 位作者 李靖 张沉思 《Journal of Central South University》 SCIE EI CAS 2014年第3期987-992,共6页
In order to save energy consumption of two-way amplifier forward(AF) relaying with channel estimation error, an energy efficiency enhancement scheme is proposed in this work. Firstly, through the analysis of two-way A... In order to save energy consumption of two-way amplifier forward(AF) relaying with channel estimation error, an energy efficiency enhancement scheme is proposed in this work. Firstly, through the analysis of two-way AF relaying mode with channel estimation error, the resultant instantaneous SNRs at end nodes is obtained. Then, by using a high SNR approximation, outage possibility is acquired and its simple closed-form expression is represented. Specially, for using the energy resource more efficiently, a low-complexity power allocation and transmission mode selection policy is proposed to enhance the energy efficiency of two-way AF relay system. Finally, relay priority region is identified in which cooperative diversity energy gain can be achieved. The computer simulations are presented to verify our analytical results, indicating that the proposed policy outperforms direct transmission by an energy gain of 3 dB at the relative channel estimation error less than 0.001. The results also show that the two-way AF relaying transmission loses the two-way AF relaying transmission loses its superiority to direct transmission in terms of energy efficiency when channel estimation error reaches 0.03. 展开更多
关键词 AMPLIFY-AND-FORWARD channel estimation error cooperative energy gain energy efficiency outage probability two-way relay
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A simplified adaptive interval Type-2 fuzzy control in practical industrial application 被引量:1
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作者 周海波 段吉安 周振宇 《Journal of Central South University》 SCIE EI CAS 2014年第7期2693-2700,共8页
Adaptive Type-2 fuzzy control possesses control performance better than the traditional adaptive fuzzy control.However,heavy computation burden obviously blocks the utilization of adaptive Type-2 fuzzy control in indu... Adaptive Type-2 fuzzy control possesses control performance better than the traditional adaptive fuzzy control.However,heavy computation burden obviously blocks the utilization of adaptive Type-2 fuzzy control in industrial application.By adopting novel piecewise fuzzy sets and center-average type-reduction,a simplified adaptive interval Type-2 fuzzy controller involving less computation is developed for practical industrial application.In the proposed controller,the inputs are divided into several subintervals and then two piecewise fuzzy sets are used for each subinterval.With the manner of piecewise fuzzy sets and a novel fuzzy rules inference engine,only part of fuzzy rules are simultaneously activated in one control loop,which exponentially decreases the computation and makes the controller appropriate in industrial application.The simulation and experimental study,involving the popular magnetic levitation platform,shows the predicted system with theoretical stability and good tracking performance.The analysis indicates that there is far less computation of the proposed controller than the traditional adaptive interval Type-2 fuzzy controller,especially when the number of fuzzy rules and fuzzy sets is large,and the controller still maintains good control performance as the traditional one. 展开更多
关键词 Type-2 fuzzy control piecewise fuzzy set adaptive fuzzy control center-average type-reduction
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Path planning for unmanned aerial vehicles in surveillance tasks under wind fields 被引量:1
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作者 张兴 陈杰 辛斌 《Journal of Central South University》 SCIE EI CAS 2014年第8期3079-3091,共13页
The optimal path planning for fixed-wing unmanned aerial vehicles(UAVs) in multi-target surveillance tasks(MTST) in the presence of wind is concerned.To take into account the minimal turning radius of UAVs,the Dubins ... The optimal path planning for fixed-wing unmanned aerial vehicles(UAVs) in multi-target surveillance tasks(MTST) in the presence of wind is concerned.To take into account the minimal turning radius of UAVs,the Dubins model is used to approximate the dynamics of UAVs.Based on the assumption,the path planning problem of UAVs in MTST can be formulated as a Dubins traveling salesman problem(DTSP).By considering its prohibitively high computational cost,the Dubins paths under terminal heading relaxation are introduced,which leads to significant reduction of the optimization scale and difficulty of the whole problem.Meanwhile,in view of the impact of wind on UAVs' paths,the notion of virtual target is proposed.The application of the idea successfully converts the Dubins path planning problem from an initial configuration to a target in wind into a problem of finding the minimal root of a transcendental equation.Then,the Dubins tour is derived by using differential evolution(DE) algorithm which employs random-key encoding technique to optimize the visiting sequence of waypoints.Finally,the effectiveness and efficiency of the proposed algorithm are demonstrated through computational experiments.Numerical results exhibit that the proposed algorithm can produce high quality solutions to the problem. 展开更多
关键词 unmanned aerial vehicle path planning in wind field Dubins traveling salesman problem terminal heading relaxation differential evolution
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Numerical investigation of optimal geometry parameters for ejectors of premixed burner
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作者 刘凤国 张蕊 +2 位作者 刘文博 翟军 郑斌 《Journal of Central South University》 SCIE EI CAS 2014年第3期1011-1016,共6页
An ejector of low NO~ burner was designed for a gas instantaneous water heater in this work. The flowing and mixing process of the ejector was investigated by computational fluid dynamics (CFD) approach. A comprehen... An ejector of low NO~ burner was designed for a gas instantaneous water heater in this work. The flowing and mixing process of the ejector was investigated by computational fluid dynamics (CFD) approach. A comprehensive study was conducted to understand the effects of the geometrical parameters on the static pressure of air and methane, and mole fraction uniformity of methane at the outlet of ejector. The distribution chamber was applied to balance the pressure and improve the mixing process of methane and air in front of the fire hole. A distribution orifice plate with seven distribution orifices was introduced at the outlet of the ejector to improve the flow organization. It is found that the nozzle exit position of 5 mm and nozzle diameter d 〉1.3 mm should be used to improve the flow organization and realize the well premixed combustion for this designed ejector. 展开更多
关键词 EJECTOR computational fluid dynamics (CFD) bumer distribution orifice premixed combustion
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Improved nonconvex optimization model for low-rank matrix recovery 被引量:1
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作者 李玲芝 邹北骥 朱承璋 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第3期984-991,共8页
Low-rank matrix recovery is an important problem extensively studied in machine learning, data mining and computer vision communities. A novel method is proposed for low-rank matrix recovery, targeting at higher recov... Low-rank matrix recovery is an important problem extensively studied in machine learning, data mining and computer vision communities. A novel method is proposed for low-rank matrix recovery, targeting at higher recovery accuracy and stronger theoretical guarantee. Specifically, the proposed method is based on a nonconvex optimization model, by solving the low-rank matrix which can be recovered from the noisy observation. To solve the model, an effective algorithm is derived by minimizing over the variables alternately. It is proved theoretically that this algorithm has stronger theoretical guarantee than the existing work. In natural image denoising experiments, the proposed method achieves lower recovery error than the two compared methods. The proposed low-rank matrix recovery method is also applied to solve two real-world problems, i.e., removing noise from verification code and removing watermark from images, in which the images recovered by the proposed method are less noisy than those of the two compared methods. 展开更多
关键词 machine learning computer vision matrix recovery nonconvex optimization
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Assessment criteria for nonverbal interaction contents in r-learning
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作者 CHOI Jong-hong LEE Jong-yun YOON Heung-seob 《Journal of Central South University》 SCIE EI CAS 2013年第9期2388-2398,共11页
r-learning,which is based on e-learning and u-learning,is defined as a learning support system that intelligent robots serve verbal and nonverbal interactions on ubiquitous computing environment.In order to guarantee ... r-learning,which is based on e-learning and u-learning,is defined as a learning support system that intelligent robots serve verbal and nonverbal interactions on ubiquitous computing environment.In order to guarantee the advantages of r-learning contents with no limits of timc and place and with nonverbal interaction which are not in e-learning contents,in recent years,assessment criteria for r-learning contents are urgently rcquired.Therefore,the reliable and valid assessment criteria were developed for nonverbal interaction contents in r-learning,and its detailed research content is as follows.First,assessment criteria for nonverbal interaction in r-learning contents will be specified into gesture,facial expression,semi-verbal message,distance,physical contact and time.Second,the validity of the developed assessment criteria will be proved by statistics.Consequently,the assessment criteria for nonverbal interaction contents will be helpful when choosing the better r-learning content and producing the better r-learning content,and the reliability of school education is improved ultimately. 展开更多
关键词 r-learning r-learning contents assessment criteria nonverbal interaction contents confirmatory factor analysis construct validity
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Effect of boron/nitrogen co-doping on transport properties of C60 molecular devices
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作者 伍晓赞 黄光辉 +1 位作者 陶庆斌 徐慧 《Journal of Central South University》 SCIE EI CAS 2013年第4期889-893,共5页
By using nonequilibrium Green's function method and first-principles calculations, the electronic transport properties of doped C60 molecular devices were investigated. It is revealed that the C60 molecular devices s... By using nonequilibrium Green's function method and first-principles calculations, the electronic transport properties of doped C60 molecular devices were investigated. It is revealed that the C60 molecular devices show the metal behavior due to the interaction between the C60 molecule and the metal electrode. The current-voltage curve displays a linear behavior at low bias, and the currents have the relation of MI〉M3〉M4〉M2 when the bias voltage is lower than 0.6 V. Electronic transport properties are affected greatly by the doped atoms. Negative differential resistance is found in a certain bias range for C60 and C58BN molecular devices, but cannot be observed in C59B and C59N molecular devices. These unconventional effects can be used to design novel nanoelectronic devices. 展开更多
关键词 negative differential resistance molecular device electronic transport property first-principles calculation
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