bob手机在线登陆学报自然版

2017, 37(7): .

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2017, 37(7): .

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Abstract:

Numerical Simulation of the Flow Field Characteristics of Low Speed Oblique Water Entry of Revolution Body

SONG Wu-chao, WANG Cong, WEI Ying-jie, Wang Wei

2017, 37(7): 661-666,667. doi:10.15918/j.tbit1001-0645.2017.07.001

Abstract(1205) PDF(1720)

Abstract:
The numerical simulation of oblique water-entry of a revolution body at low speed was performed. Finite volume method was introduced to solve the Navier-Stokes equations, and VOF (volume of fluid) and dynamic mesh method were used for the multiphase flow and the movement of the water-entry revolution body. The effectiveness of the numerical method was verified by comparison between numerical and experimental results. Based on this method, the flow field characteristics during the oblique water entry of the revolution body with different head forms at low speed were analyzed. Results show that in the same water depth, the diameters of the water-entry cavity and the minimum pressure in the flow field are larger as the cone angle of the head increases. For the revolution body with different head forms, the pressure at the same position of the the generatrix increases with larger cone angle of the head. When the angle of the cone head is larger,the pressure coefficient of the revolution body gets larger, and the velocity attenuation gets faster.

Study on the Fluid Transport Model of the High Speed Rotary Tube

ZHANG Liu-yang, WU Wei, YUAN Shi-hua, HU Ji-bin

2017, 37(7): 667-671. doi:10.15918/j.tbit1001-0645.2017.07.002

Abstract(792) PDF(1476)

Abstract:
The through-flow characteristics of the rotary tube was studied. Based on the fluid mechanics, the analytical model of the system was built. The through-flow characteristics of the rotary tube and the influencing factors were investigated in experiments. The results indicate that the flow rate of rotary tube changes with speed and oil pressure changes. In the early stage of speed increasing, flow rate change is small. As the speed increases, the weakening trend of flow ability also increases. The through-flow characteristics are positively correlated with size and number of the flow orifice. The outer diameter of the flow orifice has an effect on the centrifugal pressure and oversized outer diameter will cause oil inlet difficulties at high speed. It is necessary to consider the effects listed above in the lubrication system design of the high speed planetary transmission.

Determining Method for Spoilers Operating Condition at Low Oil Charging Ratio in Hydrodynamic Retarder

WEI Wei, LI Shuang-shuang, AN Yuan-yuan, YAN Qing-dong

2017, 37(7): 672-676. doi:10.15918/j.tbit1001-0645.2017.07.003

Abstract(1221) PDF(857)

Abstract:
In order to reveal the flow features dominated by gas phase working at low oil charging ratio and reduce idling power loss in hydrodynamic retarder, the periodic flow passage computational model of some type hydrodynamic retarder was built with spoiler which may suppress idling power loss. And the flow filed simulation was conducted to investigate the action process of spoiler inside cascades at low oil charging ratio operating condition, thus the trends of parameters such as braking torque, oil charging ratio and pressure difference of spoiler baffle were analyzed under the operating condition of different input rotating speeds and oil charging ratios. The results show that, braking torque changes significantly around 20% oil charging ratio, it reaches the maximum value before 18% oil charging ratio, while drops at 20% as local minimum value then raises again; at microscopic view the oil and air inside hydrodynamic retarder work as stratified flow below 20% oil charging ratio, however when oil charging ratio surpasses the 20% stratified flow phenomenon gets unintelligible; the spoiler baffle can be pressed into retarder case when its pressure difference value is larger than designed preload spring force. Based on these the determining method is proposed and the theoretical foundation of spoilers inside a hydrodynamic retarder is provided.

Precision Assembly Oriented Method to Determine the Evaluation Parameters for Surface Form Error

FAN Hong-li, GUO Shao-wei, ZHANG Fa-ping, ZHANG Ti-guang, WANG Ge, YAN Yan

2017, 37(7): 677-681. doi:10.15918/j.tbit1001-0645.2017.07.004

Abstract(1008) PDF(967)

Abstract:
The traditional form error evaluation methods, based on the principles of a minimum tolerance, are inadequate to quantitatively describe the vital influence of the distribution of the surface form error on the assembly precision. In this paper, a method was proposed to determine the potential evaluation parameters of surface form error for assembly precision. Firstly, non-Gaussian surface construction was used to simulate machining surface, and wavelet analysis with the selected base function was used to obtain the surface form error. The input parameters of non Gauss simulation were determined by analyzing the test parameters of the "real machined surface", and the candidate parameters characterizing the surface form error distribution were selected. Then the virtual assembly of the filtered surface with ideal smooth surface was conducted, hence the ideal surface spatial location was calculated. The relationship between the surface parameters and the second surface spatial location was established by correlation analysis to determine the form error evaluation parameters with a certain criteria. Finally a case was used to verify the feasibility proposed method. The method can provide a scientific basis for optimizing the assembly process to improve assembly precision.

Precision Assembly Geometric Error Sensitivity Analysis Based on the Error Transformation Model for Precision Assembly

YAN Yan, WANG Ge, ZHANG Fa-ping, ZHANG Ti-guang, GUO Shao-wei

2017, 37(7): 682-686. doi:10.15918/j.tbit1001-0645.2017.07.005

Abstract(897) PDF(1744)

Abstract:
In the process of multistage precision assembly, geometric error of parts is one of the important factors influencing on the assembly precision, and the method to determine the geometric error's influence and the bottleneck assembly are the primary problems. In this paper, the pose change of the parts was analyzed to concern the mating surface geometric error caused by surface topography in two parts assembly, and to determine the mating error of the single process.Based on the multi-body system theory, an error transformation model of multistage assembly process was established; and then, a sensitivity analysis model of the assembly precision was built with matrix differential method to identify the main geometric errors for the assembly system. The method provides theoretical basis for precision assembly accuracy analysis and control. Finally, an example was presented to validate the established model.

Unburned Air Mass Fraction Estimation for Model-Based EGR Turbocharged Diesel Engine Unburned Air Mass Fraction Estimation

DONG Tian-pu, LIU Bo-lan, ZHANG Fu-jun, WANG Ying-min, LIU Pan

2017, 37(7): 687-692. doi:10.15918/j.tbit1001-0645.2017.07.006

Abstract(1025) PDF(1454)

Abstract:
Intake unburned air mass fraction cannot be directly measured on production EGR turbocharged diesel engine. To deal with this problem, an innovative unburned air mass fraction estimation method for EGR turbocharged diesel engine was proposed in this paper, laying the foundation for the diesel air path control based on intake unburned air mass fraction. A dynamic model of the high pressure EGR turbocharged diesel engine was developed, and the EGR flow high gain observer was designed based on the dynamic model, to lay the foundation for the accurate estimation of the unburned air mass fraction. Based on the dynamic equations of the unburned air mass fraction in the intake and exhaust manifold, the full dimension state observer of the unburned air mass fraction was designed. The convergence stability of the observer was proved through a Lyapunov analysis. The results show that the observer can meet the stability requirements. It can be used for estimating the unburned air mass fraction. The EGR flow observer and the unburned air mass fraction observer were verified also using the GT-Power simulation data and the experimental data. The results show that the designed observers can accurately estimate the parameters, and the estimation error less than 3%, which meet the demand of diesel engine control system.

Influence of the Parasitic Damping and Additional Stiffness on the Hybrid-Connected ISD Suspension

ZHANG Xiao-liang, HUANG Zhen-xing, NIE Jia-mei

2017, 37(7): 693-697. doi:10.15918/j.tbit1001-0645.2017.07.007

Abstract(1052) PDF(1111)

Abstract:
In order to engineer the hybrid-connected ISD suspension, a design scheme was proposed in combination with hydraulic inerter and a hydro-pneumatic spring. In allusion to the problem that the parasitic damping and the additional stiffness produced in engineering may worsen the suspension performance, a quarter vehicle dynamics mathematical model was built. The impact of the parasitic damping and the additional stiffness on the suspension performance was analyzed by the simulation, and a muti-objective optimization method was used to optimize the design of the parasitic damping and the additional stiffness. The results indicate that the low frequency peak value of the power spectral density of the body acceleration, the suspension working space, and the dynamic tyre load of the engineering hybrid-connected ISD suspension decrease respectively 1.6%, 3.9%, 1.1% compared with the hybrid-connected ISD suspension. And their RMS value decrease 12.2%, 11.4%, 8.6% compared with the hybrid-connected ISD suspension. Therefore, it is necessary to limit the parasitic damping and the additional stiffness to a reasonable range by optimization design to make the suspension performance essentially constant before and after engineering. The research can provide theoretical basis for the engineering design of the hybrid-connected ISD suspension.

A Rehabilitation Robot and Its Industrial Design for Human Lower Limb Training

QIAO Yu, ZHANG Li-juan, LÜ Yun-qi, YANG Tao, GAO Xue-shan

2017, 37(7): 698-703. doi:10.15918/j.tbit1001-0645.2017.07.008

Abstract(1472) PDF(1253)

Abstract:
A rehabilitation training robot was proposed to focus on the recovery of human lower limbs function, including the recovery of walking ability of stroke rehabilitation patients, elderly person with weak motor function of lower limbs, people with lower limbs dyskinesia caused by accidents or disasters, and so on, so as to solve the shortage of intelligent rehabilitation aids. Consisting of mechanism, control system, and safety system, the robot was also integrated with various sensors. The training people with the real-time accompany of these sensors and the human-machine interaction system was attempted to achieve the functions of real-time automatically forward, left and right turning, anti-falling, and so on. Experiment results show that the system is simple and reliable. Two generations of lower limb rehabilitation training robots had been developed, the first generation had been applied in the hospital for preliminary application. In this paper, the second generation of rehabilitation training robot was improved in shape and partial function, and the design scheme of the robot was put forward, laying the technique foundation for further promotion of rehabilitation robot in the field of rehabilitation medicine.

Intercell Scheduling Approach Based on Ant Colony Optimization Algorithm and Genetic Programming

LI Dong-ni, JIA Xiao-yu, CHEN Lin, ZHENG Dan, TAO Jun

2017, 37(7): 704-710. doi:10.15918/j.tbit1001-0645.2017.07.009

Abstract(1054) PDF(907)

Abstract:
To deal with the intercell scheduling problem with limited transportation capabilities, a hyper-heuristic approach was developed based on an ant colony optimization and genetic programming algorithm. The ant colony optimization algorithm was used to search the appropriate heuristic rules for the addressed problem. And the genetic programming was used to generate well-performing heuristic rules as an extension to the predefined candidate heuristic rules. Meanwhile, a time window was introduced into the proposed algorithm to determine the vehicle waiting time for a batch processing. Experimental results show that the ant colony optimization algorithm can search the outperforming combinations of the heuristic rules, the heuristic rules generated via genetic programming can obviously improve the quality of the candidate rule set, and that the time window can obviously improve the vehicle efficiency and minimize the total weighted tardiness, therefore providing better performance.

Multi-Level Relevance Resources Coordinated Scheduling Based on Improved Genetic Algorithm

LU Zhi-bing, WANG Ai-min, TANG Cheng-tong

2017, 37(7): 711-716. doi:10.15918/j.tbit1001-0645.2017.07.010

Abstract(962) PDF(858)

Abstract:
In the actual scheduling process of production, there are multi-level relevance resources to be scheduling, like operators, machines, fixtures and cutters participate in the job-shop operation. In this paper, a new scheduling method was proposed based on improved genetic algorithm (GA) for multi-level relevance resources coordinated scheduling to combine the constraints among operators, fixtures and cutters, to be different from traditional production scheduling focusing only on machines. This method consisted mainly of two parts:an improved GA was used to match the multi-level relevance resources those meet the matching relationship, and the best combination of multi-level relevance resources through adapted calculation was saved; scheduling time calculation for multi-level relevance resources processes (MRRP) was established, and according to the processes occupancy of multi-level relevance resources, the earliest available time span was found for insert MRRP. Finally, the effectiveness of the method was demonstrated with the result analysis of practical examples.

Denoising Algorithm of Express Way Floating Car Data Based on Wavelet Threshold

WANG Hong-yu, LANG Ying, HAN Hai-hua, WANG Xiao-guang, MEI Wen-bo

2017, 37(7): 717-720,770. doi:10.15918/j.tbit1001-0645.2017.07.011

Abstract(913) PDF(1197)

Abstract:
Data denoising is a foundation work for extracting traffic information from floating car data. Wavelet analysis method shows excellent advantages in data denoising of doping noise signals. In this paper, a wavelet threshold denoising algorithm was proposed to suit data denoising of the original floating car data. According to noise-signal ratio and mean square deviation, the data denoising effect of floating car data was analyzed based on the constructed new threshold value and threshold function to determine the wavelet basis function as well as decomposition level of wavelet,so as to develop an effective algorithm for the wavelet threshold denoising of the floating car data. Results show that, the constructed wavelet threshold algorithm can improve the correlation of denoised floating car data to RTMS data by more than 10%. It means the floating car data can be effectively denoised.

Distributed News Event Hybrid Recommendation Approach

NIU Zhen-dong, WANG Shuai, WANG Shi-hang, CHEN Jie

2017, 37(7): 721-726. doi:10.15918/j.tbit1001-0645.2017.07.012

Abstract(1242) PDF(1597)

Abstract:
A distributed news event hybrid recommendation approach was proposed to improve efficiency of personalized news recommendation. In this approach, the traditional hierarchical cluster algorithm was modified to find news events, the distance weight of two cluster centers and the maximum distance weight among different clusters were modulated to avoid ‘big cluster’ in traditional hierarchical cluster. Then a hybrid recommendation algorithm was used to recommend news events, and a users' interest model with multiple event characteristics was introduced into the hybrid recommendation algorithm. At last, this approach was implemented with Spark to deal with big data recommendation. Experimental results on open collections show the effectiveness of our proposed approach.

Extension Method of SML for Intelligent Master Model

YU Cong, ZHANG Fa-ping, YAN Yan, HAO Jia, WANG Guo-xin, LÜ Wu

2017, 37(7): 727-732. doi:10.15918/j.tbit1001-0645.2017.07.013

Abstract(936) PDF(781)

Abstract:
A method of extending tabular layouts of article characteristics(SML) was proposed to solve the problem that conventional SML cannot organize multi-view, multi-level product information and design knowledge in intelligent master model(IMM). Firstly, product article characteristics were multi-view clarified to meet the requirement of information expression in IMM. Then the content of article characteristics was extended to fully express multi-view information for the whole product design process in width dimension, and knowledge matrix was used to describe the association relationship between product article characteristics and design knowledge in depth dimension to provide designer with knowledge to make design decision, and the SML was constructed form product, component and part level in granularity dimension to enable intelligent master model intelligently scaling product structure so as to quickly evaluate different product configuration in early product development stages. Effectiveness of the presented method was verified by an example of barrel design and optimization.

Action Recognition Based on Latent Task Learning

HOU Jing-yi, LIU Cui-wei, WU Xin-xiao

2017, 37(7): 733-737. doi:10.15918/j.tbit1001-0645.2017.07.014

Abstract(931) PDF(708)

Abstract:
In this paper, a novel approach based on latent task learning was presented for action recognition. A set of sub-actions shared by different actions were taken as the latent task, and then the latent task were jointly learned to model the intrinsic relationship among multiple actions for classifier training and the action recognition of video person. Specifically, a softmax based multi-class model was introduced to learn the latent tasks to avoid the ambiguity during recognition process and save the training time owing to its simple computation. Experimental results on UCF sports and Olympic sports datasets show that, compared with the binary-class based multi-task method the proposed method not only saves the running time from 130 s per iteration to 0.5 s per iteration, but also achieves better performance on action recognition tasks.

FPGA-Based High Level Integration Portable B-Imaging System

LI Da-yu, RUAN Yu-hang, SUN Dong-zheng, ZHANG Shi

2017, 37(7): 738-743. doi:10.15918/j.tbit1001-0645.2017.07.015

Abstract(892) PDF(1364)

Abstract:
A fully digitalized B-imaging system solution was presented in this paper, possessing 16 channels and 80 mapping array elements, designed with a high integration ultrasound transmitting and echo receiving circuit, being able digital ultrasound imaging based on FPGA and USB technologies. Compared with the traditional analog solutions, this solution can greatly reduce the area of the system and power consumption with better resolution and detection accuracy. It also can be adopted into the community medical service, large-scale sport events rescue and any other fields like this. Based on the presented solution, a prototype of the portable B-imaging system was made. The test result shows the feasibility of the system.

Speaking Style Recognition of Pilots in Flight

XIE Xiang, TANG Gang, XIAO Ze-ping, LI Tong

2017, 37(7): 744-747. doi:10.15918/j.tbit1001-0645.2017.07.016

Abstract(964) PDF(1116)

Abstract:
The pilots have various speaking styles in flight, such as emotional dialogue, speaking fast and slowly, speaking loudly and quietly, etc. Moreover, the physical and mental pressure of the pilots in flight can cause dialogue speech aberrance. If the speech was processed directly by the traditional speaker recognition system or a speech recognition system without any processing function, the speech performance will be poor. Therefore, the recognition of the pilots' speaking styles, a kind of paralinguistic information, was investigated to assist the subsequent speech recognition system and speaker recognition system. In the study, 6 925 samples were collected in the experiment database, 384-dimension acoustic features were extracted, and compared the classification ability of SVMs with different Kernel functions. The experiment results indicated that the SVM with Gauss radial basis Kernel function shows the best performance and its accuracy can reach 91.62%.

An Improved G.719 Audio Codec Based on Arithmetic Coded Trellis Coded Quantization

ZHAO Sheng-hui, MAO Ting, LIU Er-lang, YU Ying-ying

2017, 37(7): 748-752. doi:10.15918/j.tbit1001-0645.2017.07.017

Abstract(877) PDF(1056)

Abstract:
Arithmetic coded trellis coded quantization (actcq) is the combination of trellis coded quantization (tcq) and arithmetic coding (AC). An improved G.719 audio codec was proposed in this paper by applying ACTCQ to the G.719 audio codec. Both the objective and subjective experimental results show that, compared with the G.719 audio codec, the improved codec not only reduces the coding rate, but also obviously improves the reconstructed audio quality.

Adaptive Equalization Algorithm in Symbolic Level Based on LMS Algorithm

YANG Jie, TU Hang, WANG Yi-xia

2017, 37(7): 753-757. doi:10.15918/j.tbit1001-0645.2017.07.018

Abstract(842) PDF(847)

Abstract:
In the CDMA systems with short spreading codes, multipath interference will seriously affect the performance of receivers. Especially when the multipath delay is long, interference will spread to disturb successive symbols and cause serious interference between users and symbols. A symbolic level adaptive equalization algorithm was proposed to improve the throughput of single iteration of equalization, almost without changing the bit error rate of receivers and computation complexity. The results of simulation and hardware test show that, the new algorithm effectively suppresses the inter-user interference and inter-symbol interference caused by multipath fading, and obviously improves the throughput of one single iteration equalization, and alleviates the constraint of delay to the convergence speed, which makes it much easier for engineering application.

Improved Game-Theoretic Algorithm for Spectrum Sharing in Cognitive Radio

HAN Song, LI Xin-bin, MA Kai, LIU Zhi-xin

2017, 37(7): 758-764. doi:10.15918/j.tbit1001-0645.2017.07.019

Abstract(805) PDF(1189)

Abstract:
A distribution game-theoretic algorithm was proposed to improve the rationality and effectiveness of game strategy. First, a new price function was applied to the rare spectrum resource allocation, considering the quadratic-cost of primary users. Second, a dynamic trust value mechanism was designed to optimize spectrum sharing condition, punishing the secondary users by decreasing the trust value when they disturb the communications of primary users. Then, a hierarchical multi-period algorithm with price feedback was presented for the primary users and secondary users to get the maximum value and the spectrum utilization rate. Numerical simulation results show the rationality and effectiveness of the proposed algorithm.

A ModifiedωkAlgorithm for GEO SAR

ZHANG Xin, HUANG Pu-ming, WANG Wei-wei

2017, 37(7): 765-770. doi:10.15918/j.tbit1001-0645.2017.07.020

Abstract(833) PDF(988)

Abstract:
Considering the characteristic of the GEO SAR (geosynchronous synthetic aperture radar), a new slant range model without the "stop-go" assumption was established. Meanwhile, an advanced ωk algorithm overcoming the 2-D space-variant was proposed for GEO SAR, this algorithm adopted a new frequency axis mapping and NUFFT in both range and azimuth direction to decrease the 2-D coupling. Finally, effectiveness of the algorithm was validated by the simulations.

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