JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Numerical simulation of non-contact explosion by door breaching explosive

2013, 22(1): 1-5.

[Abstract](5097) [PDF 1809KB](2503)

Abstract:
Aiming at the estimation of personal injury attached by counter-terrorist door breaching explosive blast wave, according to the actual scene, four typical application space models of counter-terrorist door breaching explosives are established, and numerical simulation of air-blast wave propagation by non-contact explosion counter-terrorist door breaching explosive are achieved. The research results show that the overpressure behind the target door is attenuated deeply through the burglary resistant safety door, and the propagation of blast wave and the damage effect under different space conditions are obviously different.

Determining the characteristics of the initial fixed-focus of laser beam riding guidance information field

MEI Yue-song, YU Jian-qiao, YU Tian-peng, LI Jing-xu

2013, 22(1): 6-11.

[Abstract](4706) [PDF 345KB](3417)

Abstract:
Determining characteristics of the initial fixed-focus are a key technique for the design of laser beam riding guidance missile. Through analyzing the effects of the initial cone information field in guidance and control system of missile, those effects are considered as an approximate lead compensation network. The position and time of guidance spot initial fixed-focus can be designed. This method is applied to determine the characteristics of the initial fixed-focus of laser information field for a laser beam guidance gun-launched missile. The results of design and simulation show that the initial cone information field apparently speeds up convergence on the initial trajectory, and provides a guarantee for the implementation of minimum range index of a missile system.

Multi-objective optimization design for leg mechanism of hydraulic-actuated quadruped robot

MA Ming, SUN Bo, WANG Jian-zhong, SHI Jia-dong

2013, 22(1): 12-19.

[Abstract](1440) [PDF 541KB](805)

Abstract:
In order to improve the robot's abilities of bearing heavy burdens and transporting in complex terrains, the multi-objective optimization design for leg mechanism of the quadruped robot with hydraulic actuated is studied in this paper. The kinematics and dynamics of the robot are analyzed and the two-dimensional linear inverted pendulum model is adopted in planning the trajectories of joints. Then the mathematical model of valve-controlled asymmetric cylinder and control model of single leg are proposed respectively. In the end, NSGA-II algorithm is used to achieve the multi-objective optimization design of parameters concerning single leg mechanism and PD torque control. The results prove that the optimized leg mechanism can significantly reduce the required maximum power of hydraulic system, thus decrease its own weight and lead to the obtaining of good dynamic performance.

Re-entry trajectory optimization using a multiple-interval Radau pseudospectral method

HAN Peng, SHAN Jia-yuan, MENG Xiu-yun

2013, 22(1): 20-27.

[Abstract](967) [PDF 385KB](1071)

Abstract:
Aiming at increasing the calculation efficiency of the pseudospectral methods, a multiple-interval Radau pseudospectral method (RPM) is presented to generate a reusable launch vehicle (RLV)'s optimal re-entry trajectory. After dividing the optimal control problem into many intervals, the state and control variables are approximated using many fixed- and low-degree Lagrange polynomials in each interval. Convergence of the numerical discretization is then achieved by increasing the number of intervals. With the application of the proposed method, the normal nonlinear programming (NLP) problem transcribed from the optimal control problem can avoid being dense because of the low-degree approximation polynomials in each interval. Thus, the NLP solver can easily compute a solution. Finally, simulation results show that the optimized re-entry trajectories satisfy the path constraints and the boundary constraints successfully. Compared with the single interval RPM, the multiple-interval RPM is significantly faster and has higher calculation efficiency. The results indicate that the multiple-interval RPM can be applied for real-time trajectory generation due to its high efficiency and high precision.

Development of calibration system for transmission control unit of AT based on XCP

TAO Gang, LI De-qing, MA Yue-feng, DUAN Li-juan

2013, 22(1): 28-34.

[Abstract](960) [PDF 732KB](1086)

Abstract:
To guarantee control system's performance and shorten the development cycle during the development process of hydraulic automatic transmission, a calibration system on CAN for high-power AT ECU is designed based on XCP. In this system, it is possible that the master dynamically searching the slaves available on bus and data synchronization between master and slave is also achieved. Real-time measurement and on-line calibration can be executed during the running process of transmission control unit, so the calibration result is displayed in time. Calibration by true value and physical value are both available. Experimental results showed that this system operated stably and reliably and had strong timeout handling ability.

Vehicle conflict resolution algorithm at non-signalized crossing based on inter-vehicle communication

WANG Yun-peng, E Wen-juan, LIU Tian-ping, TIAN Da-xin, LU Yingrong, LU Guang-quan

2013, 22(1): 35-42.

[Abstract](1273) [PDF 487KB](654)

Abstract:
A vehicle conflict detection and resolution method is proposed based on the concept of vehicle infrastructure integration (VII) system to prevent vehicle accident beforehand at blind crossing. After analyzing traffic conflict characteristics and vehicle collision scenarios at intersection, a vehicle dynamics model and an inter-vehicle communication method are discussed. In the inter-vehicle communication environment, the relative relationship between two encountered vehicles are designed. Then vehicle conflict detection and resolution algorithms under two conflict scenarios are put forward to represent the conflict-free movements of vehicles with adjusting vehicle velocity at crossing. Finally, simulation studies are carried out and the results prove that the proposed algorithms are effective for vehicle conflict resolution at blind crossing.

Modeling and analysis of multiservice queuing system for WiMAX network

SADIA Murawwat, AKHTAR Hussain, MUHAMMAD Imran, ZHAO San-yuan, LIU Zhen-juan, NIU Hui-bo

2013, 22(1): 43-48.

[Abstract](847) [PDF 354KB](934)

Abstract:
An analytical queuing model is proposed for the classified services of WiMAX network. Simulation model is also developed that corresponds to the Markovian analytical model using Java modeling tool (JMT). This is a new and efficient discrete event tool for queuing network modeling and workload analysis. QoS metrics have been evaluated for the multi-rate traffic in multiple scenarios. Results obtained from simulation are compared for validation and analysis. Outcomes show that the proposed model is more efficient than the conventional method by improving residence time, response time, increasing system throughput and efficiency at queuing level with a slight degradation in call acceptance factor.

Design of quaternary logic circuits based on source-coupled logic

WU Hai-xia, QU Xiao-nan, CAI Qi-long, XIA Qian-bin, ZHONG Shun-an

2013, 22(1): 49-54.

[Abstract](837) [PDF 344KB](663)

Abstract:
In order to improve the performance of arithmetic very large-scale integration (VLSI) system, a novel structure of quaternary logic gates is proposed based on multiple-valued current mode (MVCM) by using dynamic source-coupled logic (SCL). Its key components, the comparator and the output generator are both based on differential-pair circuit (DPC), and the latter is constructed by using the structure of DPC trees. The pre-charge evaluates logic style makes a steady current flow cut off, thereby greatly saving the power dissipation. The combination of multiple-valued source-coupled logic and differential-pair circuit makes it lower power consumption and more compact. The performance is evaluated by HSPICE simulation with 0.18. μ m CMOS technology. The power dissipation, transistor numbers and delay are superior to corresponding binary CMOS implementation. Multiple-valued logic will be the potential solution for the high performance arithmetic VLSI system in the future.

Selfish behavior detection of cooperative relay

FU Xiao-mei, ZHAO Yan-ling

2013, 22(1): 55-59.

[Abstract](794) [PDF 313KB](635)

Abstract:
A selfish behavior detection technique is investigated to assist secure cooperative transmission at the physical layer. The detection technique calculates the correlation ratio between signals received from the diversity branches to determine the relay's behavior in amplify and forward cooperation strategy. The correlation ratio is considerably reduced because the relay's selfish behavior makes the correlation between the received signals in the diversity branch degraded. Simulation results show that the proposed mechanism can effectively detect selfish nodes and performance will be improved significantly with the destination's detection technique.

Novel non-coherent integration method using binary phase-coded radar signal

TIAN Li-yu, HE Miao, LIU Bin, FU Xiong-jun

2013, 22(1): 60-66.

[Abstract](782) [PDF 373KB](678)

Abstract:
Themseries with 511 bits is taken as an example being applied in non-coherent integration algorithm. A method to choose the bi-phase code is presented, which is 15 kinds of codes are picked out of 511 kinds ofmseries to do non-coherent integration. It is indicated that the power increasing times of larger target sidelobe is less than the power increasing times of smaller target mainlobe because of the larger target's pseudo-randomness. Smaller target is integrated from larger target sidelobe, which strengthens the detection capability of radar for smaller targets. According to the sidelobes distributing characteristic, a method is presented in this paper to remove the estimated sidelobes mean value for signal detection after non-coherent integration. Simulation results present that the SNR of small target can be improved approximately 6.5.dB by the proposed method.

Wideband interference suppression based on space-time filter

REN Chao, WANG Yong-qing, ZHOU Shan, MA Zhi-hong

2013, 22(1): 67-74.

[Abstract](1137) [PDF 1088KB](613)

Abstract:
Based upon the diagonal loading technique and the structure of the space-time adaptive processors, a novel anti-jamming method of satellite navigation is proposed. According to matrix inverse theorem, the range of the diagonal loading values for space-time adaptive wideband signal processing structure is deduced, and the optimum equation of diagonal loading beam forming algorithm of space-time structure is obtained. Then, by the analysis of two-dimensional oriented vector in direction of the perturbation interference, the wideband interference covariance matrix obtained in the weights training period is modified. Finally, the optimum weight of multi-linear constrained space-time adaptive beam-forming alogrithm is derived for anti-interference filter processing. The new method effectively widens the null steering beams when discrepancy happens. The computer simulation results prove the robustness of the proposed method.

Reputation evaluation method for open multi-agent systems

JIN Fu-sheng, DONG Ming-bin, NIU Zhen-dong, ZHANG Quan-xin

2013, 22(1): 75-80.

[Abstract](855) [PDF 332KB](550)

Abstract:
A reputation evaluation method based on multi-dimensional information representation and correlative algorithm is proposed for open multi-agent systems. First, a vector model is established to represent the reputation related information. Second, a vector based reputation model "TRUST" is put forward to evaluate the reputation of agents. Finally, a correlative algorithm for selecting the most appropriate service provider is proposed. Simulation results indicate that the method can quickly and accurately to achieve the aim of adaptive immunity to reputation fraud and improving the average gain that service consumer agents obtained.

Video events recognition by improved stochastic parsing based on extended stochastic context-free grammar representation

CAO Mao-yong, ZHAO Meng, PEI Ming-tao, ZHAO Zeng-shun

2013, 22(1): 81-88.

[Abstract](886) [PDF 1422KB](507)

Abstract:
Video events recognition is a challenging task for high-level understanding of video sequence. At present, there are two major limitations in existing methods for events recognition. One is that no algorithms are available to recognize events which happen alternately. The other is that the temporal relationship between atomic actions is not fully utilized. Aiming at these problems, an algorithm based on an extended stochastic context-free grammar (SCFG) representation is proposed for events recognition. Events are modeled by a series of atomic actions and represented by an extended SCFG. The extended SCFG can express the hierarchical structure of the events and the temporal relationship between the atomic actions. In comparison with previous work, the main contributions of this paper are as follows: ① Events (include alternating events) can be recognized by an improved stochastic parsing and shortest path finding algorithm. ② The algorithm can disambiguate the detection results of atomic actions by event context. Experimental results show that the proposed algorithm can recognize events accurately and most atomic action detection errors can be corrected simultaneously.

Audio-visual emotion recognition with multilayer boosted HMM

Lü Kun, JIA Yun-de, ZHANG Xin

2013, 22(1): 89-93.

[Abstract](805) [PDF 565KB](679)

Abstract:
Emotion recognition has become an important task of modern human-computer interaction. A multilayer boosted HMM (MBHMM) classifier for automatic audio-visual emotion recognition is presented in this paper. A modified Baum-Welch algorithm is proposed for component HMM learning and adaptive boosting (AdaBoost) is used to train ensemble classifiers for different layers (cues). Except for the first layer, the initial weights of training samples in current layer are decided by recognition results of the ensemble classifier in the upper layer. Thus the training procedure using current cue can focus more on the difficult samples according to the previous cue. Our MBHMM classifier is combined by these ensemble classifiers and takes advantage of the complementary information from multiple cues and modalities. Experimental results on audio-visual emotion data collected in Wizard of Oz scenarios and labeled under two types of emotion category sets demonstrate that our approach is effective and promising.

Greyscale based learning in BPNN for image restoration problem

UMAR Farooq, YAN Xue-mei, SADIA Murawwat, MUHAMMAD Imran

2013, 22(1): 94-100.

[Abstract](1136) [PDF 5047KB](675)

Abstract:
A new method of back propagation learning with respect to the problem of image restoration which is named as greyscale based learning in back propagation neural networks (BPNN) is investigated. It is observed that by using this method the value of mean square error (MSE) decreases significantly. In addition, this method also gives good visual results when it is applied in image restoration problem. This method is also useful to tackle the inherited drawback of falling into local minima by reducing its effect on overall system by bifurcating the learning locally different for different grey scale values. The performance of this algorithm has been studied in detail with different combinations of weights. In short, this algorithm provides much better results especially when compared with the simple back propagation algorithm with any further enhancements and without going for hybrid solutions.

Simulation of CIECAM02 color appearance model based on Chinese color system

LIANG Jing, LIAO Ning-fang, DONG Shu-wen, LIAN Yu-sheng, NIU Hai-liang

2013, 22(1): 101-105.

[Abstract](706) [PDF 308KB](881)

Abstract:
Color appearance model (CAM) can be used to determine the required colors for reproduction across changes in cross-media. CIECAM02 color appearance model prediction is implemented by artificial neural networks in this paper, which includes forward and reversed prediction. 1333 color samples as training samples and other 1332 color samples as test samples are selected in the Chinese color system. In order to test the prediction accuracy of neural networks after simulation of CIECAM02 color appearance model, the color-difference formula can be used for the evaluation of forward and reversed models. Results have shown that BP neural-network has acceptable accuracy in simulation of CIECAM02 color appearance model for colors of Chinese color system.

System dynamics simulation of the civil-military integrated innovation system of military enterprises

ZHANG Ji-hai, WANG Chao

2013, 22(1): 106-113.

[Abstract](856) [PDF 393KB](635)

Abstract:
Civil-military inosculation of military enterprises benefits national defense industries by promoting the building of civil-military inosculation innovation system. To analyze the operation mechanism of the civil-military integrated innovation system of the military enterprises under the new situation, the system dynamics method is used to study the feedback relations among the factors and structure of the system and the Anylogic software is used to establish the simulation model. The simulation results indicate that: the degree of enthusiasm of private enterprises to participate in the defense industry, the degree of information sharing and the degree of cooperation between the military enterprises and universities and research institutions are extremely important in the civil-military integrated innovation system. According to the simulation results, some targeted suggestions are put forward to strengthen the innovational civil-military integrated system building of the military enterprises.

Preparation and chromatographic evaluation of thermoresponsiveN-isopropylacrylamide copolymers stationary phases containing amino groups

LIU Zong-jian, DAI Rong-ji, HU Na, HASAN Murtaza, ZHANG Yu-kui, LV Fang, DENG Yu-lin

2013, 22(1): 114-125.

[Abstract](1043) [PDF 537KB](1222)

Abstract:
Two cationic thermoresponsive stationary phases were designed and prepared containing poly[N-isopropylacrylamide-co-(2-dimethylamino)ethylmethacrylate] and poly [N-isopropylacrylamide-co-(2-diethylamino)ethylmethacrylate] via a simple method, the direct copolymerization of monomers with double bonds on silica surfaces. The two copolymers were synthesized by radical polymerization and then characterized using Fourier transform infrared and gel permeation chromatography. The thermoresponsive property and amounts of copolymers grafted on silica were determined through transmittance measurements and thermogravimetric analysis, respectively. The copolymers grafted silica particles were then applied as high-performance liquid phase (HPLC) stationary phases for chromatographic separation. Chromatographic properties of mobile phases at different pH values were evaluated by changing temperatures and using benzene and hydrocortisone as the test analytes. Retention time of the analytes was prolonged with increasing temperature on both thermoresponsive columns due to enhanced hydrophobic interaction between analytes and stationary phases. The resolution increased with increasing pH of mobile phase. The optimal separation was obtained at phosphate buffer solution (10.mM, pH 8.0) and at 50.℃. The pH of mobile phase had a crucial effect on separation efficiency. The results illustrated that poly copolymer modified silica was more advantageous for the temperature-responsive chromatographic separation because its lower critical solution temperature was relatively lower compared to the poly[N-isopropylacrylamide-co-(2-diethylamino)ethylmethacrylate] copolymer modified silica was more advantageous for the temperature-responsive chromatographic separation because its lower critical solution temperature was relatively lower compared to the poly[N-isopropylacrylamide-co-(2-dimethylamino)ethylmethacrylate] stationary phase.

Welding nanofiber and microsphere with carbon dioxide

WANG Dong, WANG Xiang-ke, GAO Hong, XING Yan

2013, 22(1): 126-129.

[Abstract](699) [PDF 1566KB](715)

Abstract:
Two types of micro/nano structures, microsphere and nanofibre, were prepared by electro spinning technique and spray drying technique, with the soluble fluorinated poly (ether ether ketone) (3F-PEEK) as the matrix. The micro/nano structures were exhibited in the scanning electron microscope (SEM) micrograghs, and the separated nanofibre and microsphere were observed. The sizes of micro/nano structures were measured by the statistical analysis method. We designed experiments to connect up all the micro/nano structures to form new three dimensional micro/nano structures that were observed by SEM. In the experiments, supercritical carbon dioxide (CO₂) was selected as the welding solvent. A series of nanofibers were welded to form three dimensional netlike structures, and the particles were welded to form a porous film. The welding processes were studied by varying the exposure temperature, and the welding mechanism was discussed.

Improvement in synthesis of 3'-N-demethylazithromycin and its derivatives

FU Yan-jie, SUN Li-quan, FAN Xin-yuan, LIU Cong, YAO Guo-wei, LUO Ai-qin

2013, 22(1): 130-134.

[Abstract](2124) [PDF 319KB](1889)

Abstract:
3'-N-demethylazithromycin is an impurity in azithromycin drug. It is derived by demethylation of azithromycin, i.e., azithromycin loses a methyl group on the 3'-Nposition. In this study, bulk product was purified with chromatographic separation. It was observed that 3'-N-demethylazithromycin was also a precursor of other impurities. Simultaneously, another derivative was synthesized, i.e., 3'-N-demethyl-3'-N-formylazithromycin. Reaction conditions were optimized with the HPLC method and good-quality and high-yield derivative product was achieved. The structures of derivatives were identified by¹H-NMR and MS.

Novel semicarbazide-sensitive amine oxidase inhibitor screening from anti-obesity drugs using HPLC-MS based technique

CHE Bao-quan, WANG Lin, ZHANG Yong-qian, XIAO Sheng-yuan, DENG Yu-lin

2013, 22(1): 135-142.

[Abstract](653) [PDF 395KB](657)

Abstract:
Semicarbazide-sensitive amine oxidase (SSAO) has been considered to be associated with the metabolism of glucose and fat, and elevated SSAO activity was observed in obese patients. In the present study, an in vitro SSAO activity-based method was developed to screen inhibitors from 15 anti-obesity drugs. Among the fifteen anti-obesity drugs, four drugs including caffeine, fenfluramine, bumetanide and amfebutamone inhibited SSAO activity, and caffeine was the most effective one. When the concentration of caffeine was 1.4.mmol/L, the inhibition ratio was 31.9% and 18.8% in rabbit serum and rat adipose tissue, respectively. Inhibition of SSAO activity by caffeine was also confirmed in the in vivo study, showing the inhibition ratio of 15.6% on serum SSAO. Caffeine provides a natural source of inhibition of SSAO activity and may be a promising inhibitor for the study of SSAO.

2013 Vol. 22, No. 1