JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Lie symmetries and conserved quantities for generalized Birkhoff system

2011, 20(3): 285-288.

[Abstract](787) [PDF 276KB](326)

Abstract:
To study Lie symmetry and the conserved quantity of a generalized Birkhoff system with additional terms, the determining equations of the Lie symmetry of the system is derived. A conserved quantity of Hojman’s type and a Noether’s conserved quantity are deduced by the Lie symmetry under some conditions. One example is given to illustrate the application of the result.

Detached-eddy simulation of supersonic turbulent flow over rearward facing step

WANYAN Zhen-hai, FENG Shun-shan

2011, 20(3): 289-294.

[Abstract](888) [PDF 544KB](341)

Abstract:
Detailed formulation of the detached-eddy simulation (DES) based on shear stress transport model (SST) was deduced. Based on finite volume method, detached-eddy simulation of supersonic turbulent flow over rearward facing step was conducted. Multi-block structured non-conform grid was designed. The obtained distribution of wall pressure coefficient along the downstream of the step was in good agreement with experiment. The structure of supersonic flow over rearward facing step is complicated and contains boundary layer-shock interaction, shock-shock interaction and secondary flow separation. The predictions of the corner pressure and location of the reattachment shock are more exact than the Reynolds-averaged method. Results show that detached-eddy simulation can simulate the supersonic separated flows exactly and has advantages over Reynolds-averaged method. The partition of the detached-eddy simulation can be easily achieved by using multi-block non-conform grid, which reduces the requirement of the computational resources as well.

Rheology of typical emulsifiers and effects on stability of emulsion explosives

WANG Li-qiong, WANG Na-feng, FANG Jie

2011, 20(3): 295-300.

[Abstract](859) [PDF 375KB](511)

Abstract:
Structure of emulsifiers or functionality and molecular weight determines its rheology, emulsification and stability of emulsion explosives. Rheology of typical emulsifiers was studied by automatic rheometer. Relations between rheology and structural properties of typical emulsifiers were analyzed. Experimental results show that viscosity of emulsifiers didn’t change with shear rate at room temperature and appeared properties of Newtonian fluid. Viscosity of different component emulsifiers declines with temperature in different modes. The change of strain doesn’t affect modulus of emulsifiers. Loss modulus increases linearly with the increase of frequency in oscillation and storage modulus does non-linearly. The higher the temperature is, the lower change amplitude of loss modulus with frequency will be. The emulsifiers with imide and amide functionality for emulsion explosives have better shear properties at high temperature and better shapingness and stability at room temperature than other emulsifiers with ester and Sorbin Monoleate (SMO) functionality.

Experimental investigation on microstructure behavior of premixed methane-air flame-flow interaction in a semi-vented chamber

REN Shao-feng, WANG Yu-jie, CHEN Xian-feng, CHEN Ming

2011, 20(3): 301-305.

[Abstract](747) [PDF 980KB](268)

Abstract:
To explore the premixed methane-air flame microstructure behavior and the flame-flow interaction, the premixed methane/air flame was studied in a semi-vented chamber. A high speed camera and schlieren images methods were used to record the processes of interaction between rarefaction wave and flame. Meanwhile, a pressure sensor was utilized to catch the pressure variation in the process of flame propagation. The experiment results showed that the interference of rarefaction wave on flame caused the flame front structure change, which led to the flame transition from laminar to turbulent quickly. The rarefaction wave intervened in the flame by turning the flame front surface into dentiform structure. The violent turbulent combustion began to appear in part of the flame front and spreaded to the whole flame front surface. The rarefaction also decreased the flame propagation speed.

Design of in-line multipoint initiation control system

LI Shou-dian, YUAN Shi-wei, ZENG Qing-xuan

2011, 20(3): 306-311.

[Abstract](1009) [PDF 449KB](212)

Abstract:
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 instruments technology was designed by the prevailing software of Laboratory Virtual Instrument Engineering Workbench (LabVIEW). It provides users a real-time status of the hardware circuit system. Moreover, 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 future weapon system. Surely, it will become one of the development directions for intelligent initiation system.

Method for high reliability evaluation of explosive initiator based on sensitivity distribution order restricted theory

WEN Yu-quan, ZHANG Li-min, HONG Dong-pao, HAO Zhi

2011, 20(3): 312-316.

[Abstract](703) [PDF 298KB](259)

Abstract:
Based on the hypothesis testing theory and sampling inspection, and utilizing the distribution parameters obtained by order restricted method, the matter of reliability index verification is transformed into testing the scale parameters of distribution. Thus, a lower stimulus level is selected, and small sample size specimens are tested to verify the high reliability at required stimulus level. Analysis for mean square error of verification test stimulus level is taken, and the result demonstrates that it is reasonable to confirm the test scheme using the order restricted estimation. The new method is used for reliability verification of the stab detonator comparing with run-down method. The result shows that it is available for verification of high reliability explosive initiator by small sample size.

Time-to-go weighted optimal trajectory shaping guidance law

WANG Hui, LIN De-fu, CHENG Zhen-xuan

2011, 20(3): 317-323.

[Abstract](1123) [PDF 378KB](275)

Abstract:
For maneuvering target, the optimal trajectory shaping guidance law which can simultaneously achieve the designed specifications on miss distance and final impact angle was deduced using optimal control theory based on the time-to-go weighted function. Based on the same cost function, the closed-form solutions of the guidance law were derived when the initial displacement of missile, final impact angle, heading error and target maneuver was introduced into the lag-free guidance system. To validate the closed-form solutions, the simulation of the lag-free system was done and the simulation results exactly matched the closed-form solutions and only when the exponent is greater than zero, the final acceleration approaches to zero.

Uncertainty quantification for a flapping airfoil with a stochastic velocity deviation

ZHAO Liang-yu, YANG Shu-xing, XU Yong

2011, 20(3): 324-330.

[Abstract](1308) [PDF 579KB](234)

Abstract:
An outdoor flapping wing micro air vehicle (FWMAV) should be able to withstand unpredictable perturbations in the flight condition. The responses of the time-averaged thrust coefficient and the propulsive efficiency with respect to a stochastic flight velocity deviation were numerically investigated. The deviation was assumed to obey the Gauss distribution with a mean value of zero and a specified standard deviation. The probability distributions of the flapping performances were quantified by the non-intrusive polynomial chaos method. It was observed that both of the time-averaged thrust coefficient and the propulsive efficiency obeyed Gauss-like but not the exact Gauss distribution. The velocity deviation had a large effect on the time-averaged thrust coefficient and a small effect on the propulsive efficiency.

Research on in-light alignment error model based on quaternion and rotation vector

XU Guo-qiang, MENG Xiu-yun

2011, 20(3): 331-338.

[Abstract](882) [PDF 388KB](247)

Abstract:
Euler angle error model, rotation vector error model (RVE) and quaternion error model (QE) were qualitatively and quantitatively compared and an in-flight alignment filter algorithm was designed. This algorithm used extended Kalman filter (EKF) based on RVE and QE separately avoiding the accuracy problem of the Euler angle model and used Rauch-Tung-Striebel(RTS) smoothing method to refine the accuracy recuperating the coning error for simplified RVE. Simulation results show that RVE and QE are more adapt for nonlinear filter estimation than the Euler angle model. The filter algorithm designed has more advantages in convergence speed, accuracy and stability comparing with the algorithm based on the three models separately.

Comparison of linear and nonlinear aerodynamic parameter estimation approaches for an unmanned aerial vehicle using unscented Kalman filter

LI Meng, LIU Li, S. M. VERES

2011, 20(3): 339-344.

[Abstract](718) [PDF 590KB](422)

Abstract:
Aerodynamic parameter estimation provides an effective way for aerospace system modeling using measured data from flight tests, especially for the purpose of developing elaborate simulation environments and designing control systems of unmanned aerial vehicle (UAV) with short design cycles and reduced cost. However, parameter identification of airplane dynamics by nonlinear models is complicated because of the noisy and biased sensor measurements. Using linear models for system identification is an alternative way if the fidelity can be guaranteed, as control design procedures are better established in linear systems. This paper considers the application and comparison of linear as well as nonlinear aerodynamic parameter estimation approaches of an UAV using unscented Kalman filter (UKF). It also highlights the degree of deterioration of the linear model in the UKF identification process. The results show that both the linear and nonlinear methodologies can accurately estimate the control system design. Furthermore, considering loss of accuracy to be negligible, the linear model can be employed for control design of the UAV as presented here.

Trajectory shaping guidance law with terminal impact angle constraint

LIU Da-wei, XIA Qun-li, WU Tao, QI Zai-kang

2011, 20(3): 345-350.

[Abstract](2669) [PDF 347KB](610)

Abstract:
In order to strike hard targets underground or warships and tanks with expected impact angle by missiles or guided bombs, trajectory shaping guidance law with terminal position and impact angle constraints is derived based on linear quadratic optimal control theory. The required acceleration expressed by impact angle and heading error is obtained in lag-free guidance system in order to find the optimal relationship of those angles in terminal phase. The adjoint systems of miss distance and impact angle error of first-order guidance system are established based on statistical linearization adjoint method (SLAM) in order to study the impact performances of the guidance law. Simulation results show that the miss distance and impact angle error of trajectory shaping guidance law are both according with the impact position and angle constraint and the required acceleration at impact can be decreased by an optimal relationship of impact angle and heading error.

Design method and vibration testing of a reconfigurable multi-process combined turn-milling machine tool

FAN Xu-xiao, ZHANG Zhi-jing, JIN Xin, SUN Xu-yao, GUO Na

2011, 20(3): 351-358.

[Abstract](898) [PDF 532KB](190)

Abstract:
To provide a good machining method in remanufacturing for the repaired parts with various forms, the design method of reconfigurable multi-process combined machining system and its implementation technology for remanufacturing are systematically proposed. The key technologies include reconfigurable structure design method of multi-process combined machining, man-machine coordination parameter programming and control system technology with self-maintenance function. A turn-milling machine tool based on this design method is developed. Natural frequency and corresponding vibration modes of the machine tool were analyzed by using both FEA and vibration test. Stiffness tests and machining experiments show that the rapid machining of most processes for the repaired work pieces can be successfully realized.

Numerical model of on-road emission rates of diesel buses in Beijing

WANG Ai-juan, GE Yun-shan, TAN Jian-wei, DING Yan, YU Lin-xiao, FENG Xiang-yu, GUO Jia-dong

2011, 20(3): 359-364.

[Abstract](787) [PDF 410KB](223)

Abstract:
A total of 14 in-use diesel buses were selected to conduct emission measurement using a portable emissions measurement system (PEMS) in Beijing. Their instantaneous gaseous emission rates, particular matter (PM) emission rates and driving parameters were obtained. The influences of speed, acceleration and vehicle specific power (VSP) on emissions were analyzed. Based on the relationships between these driving parameters and emissions, 24 driving bins defined by speed, acceleration and VSP were constructed with cluster analysis to group emission rates for Euro Ⅲ and Ⅳ buses, respectively. Then the emissions reductions from Euro Ⅲ to Euro Ⅳ diesel buses were analyzed. Lastly, on-road hot-stabilized emission rate model for diesel buses in Beijing was developed. Through the comparison of the model simulation emission rates with the measured emission rates, the modeled emission results were in good agreement with the measured emission results. In most of the cases, the differences were less than 12.%.

Prediction of a V-8 diesel engine’s structural radiated noise and research of important parameters’ effects on the engine’s acoustic behaviors

FENG Hui-hua, ZHANG Zhi-yuan, LU Shou-wei, ZUO Zheng-xing

2011, 20(3): 365-371.

[Abstract](733) [PDF 439KB](193)

Abstract:
Based on the coupled boundary element method-finite element method (BEM-FEM) method and the acoustic transfer vector (ATV) technology, BEM/FEM model is proposed for a V-type eight cylinders engine acoustic radiation simulating analysis under semi-anechoic condition. Acoustic radiation power, field points sound pressure level and panel contributions are calculated by acoustic radiation response analysis. Additionally, based on the engine acoustic performance, different acoustic behaviors of engine are studied by changing engine materials, oil pan structures as well as geometry parameters. The acoustic performance of this engine is predicted and the influence of material, structural and geometry parameters on engine radiated noise are generalized. The principle will guide the design and optimization of the engine prototype in further work.

Study on singularity analysis with differential transform method for 3-RRUR parallel robot based on Jacobian matrix

DONG Que, JIANG Zhi-hong, HUANG Qiang

2011, 20(3): 372-378.

[Abstract](838) [PDF 620KB](204)

Abstract:
Parallel robot is used in many different fields nowadays, but the singularity of 3-RRUR parallel robot is more complicated,so a method to analyze the singularity of the 3-RRUR parallel robot is very necessary. First, the Jacobian matrix was built based on the differential transform method through the transfer matrixes between the poles. The connection between the position parameters and singularity condition was built through the analysis of the Jacobian matrix. Second, the effect on the singularity from the position parameters was analyzed, and then the singularity condition was confirmed. The effect on the singularity condition from position parameters was displayed by the curved surface charts to provide a basic method for the designing of the parallel robot. With this method, the singularity condition could be got when the length of each link is firmed, so it can be judged that if a group of parameters are appropriate or not, and the method also provides warrant for workspace and path planning of the parallel robot.

Product-design knowledge retrieval based on ontology

CHEN Si, YAN Yan, WANG Guo-xin, WANG Zhao

2011, 20(3): 379-386.

[Abstract](880) [PDF 431KB](203)

Abstract:
In order to improve the utilization ratio of knowledge retrieval, a product-design knowledge retrieval approach based on ontology is proposed. A representation model of product-design knowledge is proposed according to its characteristics. Domain ontology of product-design is established and the semantic annotation technology is used to connect the design knowledge and ontology. A new semantic annotation format is developed and semantic information of the design knowledge is enriched by making use of ontology. On that basis a retrieval algorithm is designed for semantic retrieval. Finally, this approach is used in a knowledge management system for military-vehicle design and its effectiveness and feasibility are validated. Results show that the recall ratio and the precision ratio of knowledge retrieval are improved greatly and users’ requirements in semantic retrieval are satisfied.

Optimal gear shift control strategy for positive independent mechanical split path transmission with automatic shift system

CHEN Yong-dan, XI Jun-qiang, CHEN Hui-yan

2011, 20(3): 387-393.

[Abstract](1054) [PDF 750KB](226)

Abstract:
An improvement strategy which controls the shift effort and the power summing planetary gear set of steering clutches and brakes have been proposed based on the dynamic model of synchroniser in order to decrease the wear of synchroniser inserts, make gear shift easy and reduce the shock noise for a positive independent mechanical split path transmission which attached an automatic shift system when shifting. A kinetics model for the process of synchroniser engagement is built and analyzed in the paper. Thus for optimizing the gear shift process which is divided into three phases a model reference fuzzy self-adaption system is adopted. Through a 6.000 km road experiment, the control strategy has proved feasible and dependable.

Mode switching control strategy of dual motors coupled driving on electric vehicles

ZHANG Cheng-ning, WU Xiao-hua, WANG Zhi-fu, TIAN Zhen

2011, 20(3): 394-398.

[Abstract](898) [PDF 326KB](201)

Abstract:
Based on analyzing the structure and working principle on electric vehicles (EVs) with dual motors coupled by planetary gears, the control strategy of mode switching was proposed. The power interruption problem on EVs with automatic mechanical transmission (AMT) shifting was resolved. Based on the speed-torque characteristics of the planetary gears and the principle of the auxiliary motor’s zero speed braking, control features of mode switching were introduced. The mode shifting between the main motor mode and dual motors coupled driving were studied. Matlab/Simulink was adopted as a platform to develop the simulation model of EVs with dual motors drive system and 3 gears AMT. Simulation results demonstrated that the power interruption of dual motors drive system was solved during mode switching. The power requirements of EVs were satisfied, too.

Feature subset selection method for AdaBoost training

ZHAO San-yuan, SHEN Ting-zhi, SUN Chen-sheng, LIU Peng-zhang, YUE Lei

2011, 20(3): 399-402.

[Abstract](882) [PDF 282KB](189)

Abstract:
The feature-selection problem in training AdaBoost classifiers is addressed in this paper. A working feature subset is generated by adopting a novel feature subset selection method based on the partial least square (PLS) regression, and then trained and selected from this feature subset in Boosting. The experiments show that the proposed PLS-based feature-selection method outperforms the current feature ranking method and the random sampling method.

Novel routing protocol for heterogeneous wireless sensor networks

LI Xiao-yang, Henry Shi Li, SONG Wei

2011, 20(3): 403-409.

[Abstract](632) [PDF 378KB](220)

Abstract:
An improved LEACH for heterogeneous wireless sensor networks is proposed. Nodes are distributed in a sensing area that is divided into a number of same equilateral hexagons. Heterogeneous nodes act as the cluster heads and ordinary nodes act as those cluster sensors in all clusters. The structure of WSNs is a two-layer structure. The upper layer consists of all cluster heads and the lower layer consists of all ordinary sensors managed by their corresponding cluster heads. The cluster heads and the ordinary sensors establish their pairwise keys respectively through utilizing different methods. The arithmetic balances energy expense among all kinds of nodes, saves the node energy, and prolongs the life of wireless sensor networks. Additionally, Analysis demonstrates that the security of wireless sensor networks has been improved obviously even with some heterogeneous nodes.

100-112.Gbit/s complete ETDM systems based on monolithically integrated transmitter and receiver modules

WANG Ke, LI Jie, Anders Djupsjöbacka, Marek Chaciński, Urban Westergren, Sergei Popov, Gunnar Jacobsen, Volker Hurm, Robert Elvis Makon, Rachid Driad, Herbert Walcher, Josef Rosenzweig, Andreas G. Steffan, G. Giorgis Mekonnen, Heinz-Gunter Bach, LI Zhuo, Ari T. Friberg

2011, 20(3): 410-414.

[Abstract](879) [PDF 424KB](243)

Abstract:
Traditional intensity modulated two-level electrical time-division multiplexing (ETDM) transmission systems working at 100-112.Gbit/s were investigated. The complete ETDM systems based on monolithically integrated transmitter and receiver modules were demonstrated with bit-error-rate (BER) performance of 10^-8at 107.Gbit/s, and near error-free standard forward error correction (FEC) threshold (2×10^-3) at 112.Gbit/s. The experiment results showed that directly modulated high-speed ETDM transmission systems with the symbol rates at 100.Gbaud and beyond were promising candidate for cost-effective 100.GbE applications and might be a preform of the next generation of Terabit/s Ethernet.

Grid-based computer-generated holograms synthesizing for holographic three-dimensional display

CHEN Guo-hua, ZHANG Ai-jun

2011, 20(3): 415-420.

[Abstract](986) [PDF 972KB](201)

Abstract:
To reduce the computing time of composite computer-generated holograms (CGHs) generation based upon the angular projection algorithm for holographic three-dimensional (3D) display, a grid-based holographic display (GHD) scheme was designed. The grid computing technology was applied to numerically process the different angular projections of an object in distributed-parallel manner to create the corresponding CGHs. The whole treatment of a projection was regarded as a job executed on the grid node machine. The number of jobs which were submitted to grid nodes, therefore, was equal to that of the projections of the object. A Condor-based grid testbed was constructed to verify the feasibility of the GHD scheme, and a graphical user interface (GUI) program and several service modules were developed for it. A 3D terrain model as an example was processed on the testbed. The result showed that the scheme was feasible and able to improve the execution efficiency greatly.

Autoregressive moving average model as a multi-agent routing protocol for wireless sensor networks

HUANG Ru, HUANG Hao, CHEN Zhi-hua, HE Xing-yong

2011, 20(3): 421-426.

[Abstract](716) [PDF 373KB](259)

Abstract:
A prediction-aided routing algorithm based on ant colony optimization mode (PRACO) to achieve energy-aware data-gathering routing structure in wireless sensor networks (WSN) is presented. We adopt autoregressive moving average model (ARMA) to predict dynamic tendency in data traffic and deduce the construction of load factor, which can help to reveal the future energy status of sensor in WSN. By checking the load factor in heuristic factor and guided by novel pheromone updating rule, multi-agent, i.e., artificial ants, can adaptively foresee the local energy state of networks and the corresponding actions could be taken to enhance the energy efficiency in routing construction. Compared with some classic energy-saving routing schemes, the simulation results show that the proposed routing building scheme can ① effectively reinforce the robustness of routing structure by mining the temporal associability and introducing multi-agent optimization to balance the total energy cost for data transmission, ② minimize the total communication consumption, and ③ prolong the lifetime of networks.

2011 Vol. 20, No. 3