JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Investigation on the Determination of Initial Shock Pressure at Near Interface Field of TNT Charge and Water for Underwater Explosion

WU Cheng, ZHANG Xiang-rong, HUANG Feng-lei, SHI Jing-zhu, ZHANG Yu-xia

2007, 16(2): 127-130.

[Abstract](115)

Abstract:
There are few report on the directly measurement of the initial shock pressure of explosive charge at its interface of water for underwater explosion. The special technologies have been taken to the measurement system with manganin piezoresistive gauge (PRG) in order to measure the initial shock pressure at the interface and its near field of TNT chare and water. The free-holding PRG film gauge can directly determine the shock peak pressure at the interface and near field of TNT charge up to 12.85 GPa, which is satisfying for the good agreement to the 12.97 GPa with one dimensional theoretical analysis and 12.86 GPa with numerical simulation. The maximum discrepancy is 0.93%. The results show that it is precise and reliable to determine the initial shock pressure of underwater explosion charge with the PRG technology.

Geomaterial Constitutive Models in Toe-Shooting Method

QIAO Ji-yan, DING Hua, ZHENG Zhe-min

2007, 16(2): 131-134.

[Abstract](83)

Abstract:
For toe-shooting method, geomaterial constitutive models concerned are studied. Analysis shows that, although extensively applied in soil mechanics, due to its angular singularity of yielding surface, the Mohr-Coulomb model is not suitable for numerical simulations in large deformation; in this case the rock-fills may be regarded as the Drucker-Prager model and the seaooze as the Prandtl-Reuss model. By comparing experimental data with numerical results, the constitutive model of the seaooze is numerically verified. It shows that, in high strain rate stage forming the blasting crater, the seaooze behaves as ideal non-compressible fluid, while in low strain rate stage during which the rock-fills flow to the blasting crater, the viscosity of the seaooze is negligible.

Critical Suction Characteristic Analyses of a Wall Climbing Robot

XU Dai-jun, GAO Xue-shan, WU Xiao-bing, FAN Ning-jun, LI Ke-jie, ZHU Wei

2007, 16(2): 135-139.

[Abstract](163)

Abstract:
A new method called critical suction is used based on the wall climbing robot demands of miniature structure, moving smartly and low noise. It makes the robot achieve the homeostasis state in the suction cup, and in this condition the robot can stay on the wall reliably and move smartly. The fluid mechanics model and fluid network model are set up to analyze the robot suction system when the airflow is steady or changes suddenly. Furthermore, simulation results indicate the close relation between the key parameters of robot structure and the suction system. Finally the method of critical suction proves correct in theory.

Modal Correlation Based Analysis on Dynamic Characters of a Commercial Semi-Trailer's Chassis Frames

FENG Hui-hua, ZUO Zheng-xing, LIAO Ri-dong, LONG Kai

2007, 16(2): 140-145.

[Abstract](165)

Abstract:
In order to evaluate two different schemes' structural dynamic characters, dynamic response analysis of a commercial truck's main chassis frames is carried out. On the basis of correlation study between the tested and calculated modal results, the assembled frames' finite element analysis (FEA) models with sufficient precision are built up. Random response analysis in frequency domain is carried out with these FEA models, RMS values of von Mises and main principle stresses of these two frames are obtained. It shows that the analysis results of the distributing tendency and concrete value ranges are coincident very well with test results. And from the results, it could be concluded that frames of scheme A endures relative better loading conditions and should be adopted as the final scheme.

Analysis of Force Characteristic and Friction State on the Sealing Ring Used in Composite Transmission

HU Ji-bin, JIANG Chao, SUN Guang-hui

2007, 16(2): 146-150.

[Abstract](166)

Abstract:
Based on analysis of flow field of the rotary seal using sealing ring, mechanical models under the condition of full film friction and mixed film friction were established respectively. The influence of friction state of the sealing ring on seal performance was also discussed. The relation between force characteristic and structural parameters of the sealing ring was analyzed. Analytical results indicate that friction state mainly depends on structural parameters of the sealing ring. The expression of calculating friction torque under the condition of mixed film friction was deduced. Experiment verification had been done. Experimental results agree with the deducing theoretical conclusions on the whole. It lays the foundation for design of new type of sealing ring used in composite transmission.

Genetic Algorithm Based Combinatorial Auction Method for Multi-Robot Task Allocation

GONG Jian-wei, HUANG Wan-ning, XIONG Guang-ming, MAN Yi-ming

2007, 16(2): 151-156.

[Abstract](215)

Abstract:
An improved genetic algorithm is proposed to solve the problem of bad real-time performance or inability to get a global optimal/better solution when applying single-item auction (SIA) method or combinatorial auction method to multi-robot task allocation. The genetic algorithm based combinatorial auction (GACA) method which combines the basic-genetic algorithm with a new concept of ringed chromosome is used to solve the winner determination problem (WDP) of combinatorial auction. The simulation experiments are conducted in OpenSim, a multi-robot simulator. The results show that GACA can get a satisfying solution in a reasonable shot time, and compared with SIA or parthenogenesis algorithm combinatorial auction (PGACA) method, it is the simplest and has higher search efficiency, also, GACA can get a global better/optimal solution and satisfy the high real-time requirement of multi-robot task allocation.

Network Resource Provisioning for IP over Multi-Granular Optical Networks

SUN Jian-wei, POO Gee-Swee

2007, 16(2): 157-162.

[Abstract](207)

Abstract:
In the internet protocol(IP) over multi-granular optical switch network (IP/MG-OXC), the network node is a typical multilayer switch comprising several layers, the IP packet switching (PXC) layer, wavelength switching (WXC) layer and fiber switching (FXC) layer. This network is capable of both IP layer grooming and wavelength grooming in a hierarchical manner. Resource provisioning in the multi-granular network paradigm is called hierarchical grooming problem. An integer linear programming (ILP) model is proposed to formulate the problem. An iterative heuristic approach is developed for solving the problem in large networks. Case study shows that IP/MG-OXC network is much more extendible and can significantly save the overall network cost as compared with IP over wavelength division multiplexing network.

3D-Route Planning Method to Realize Missile Cruise Flight

WANG Zheng-jie, FAN Chen, ZHU Quan-min, TANG Wei

2007, 16(2): 163-167.

[Abstract](120)

Abstract:
In order to increase the aircraft's survival in the flight mission, it is necessary to carry out flight mission planning, which includes TF/TA2(terrain following/terrain avoidance/threat avoidance). An approach to 3D-route planning based on A heuristic search algorithm was selected to determine the routes of fiber optic guidance missile's cruise segment. The cost function was discussed, which was mainly related to the physical obstacle, threat exposure, and aircraft performance characteristics. The digital map techniques were presented, which included setting “no-go” area according to fiber's safety requirement. The optimal or the sub-optimal route was obtained, while the cost function constraints were satisfied and the stored terrain obtained from a real terrain was digitized. The algorithm is validated through simulation and can fulfill the route planning task which focuses on the cruise segment of fiber optic guidance missile.

Key Techniques of Terminal Correction Mortar Projectiles

XU Jin-xiang

2007, 16(2): 168-172.

[Abstract](187)

Abstract:
The operational principle, the impulse force and terminal guidance laws of terminal correction mortar projectiles(TCMP) are researched in this paper, by using the TCMP simulation program, key techniques such as the miss distance influenced by the acting point of impulse force, the impulse force value, the correction threshold, and the number of impulse rockets are researched in this paper. And the dual pulse control scheme is also studied. Simulation results indicate that the best acting point is near the center of gravity, sufficient correction resources are needed, the miss distance is insentive to the correction threshold, increasing the number of impulse rockets properly is beneficial to increase the hit precision, the velocity pursuit guidance law has less miss distance, the change of the attack angle is milder and the transient time becomes less in the dual impulse control scheme. These conclusions are important for choosing parameters and impulse correction schemes designed for TCMP.

H₂Output Feedback Control for Airborne Dispenser Uncertain Generalized System

LV Hong-jian, LIU Zao-zhen, SHAN Jia-yuan

2007, 16(2): 173-176.

[Abstract](190)

Abstract:
The problem of H2 output feedback control for generalized system with structural uncertainties is studied using linear matrix inequality approach. A sufficient condition of linear matrix inequality is presented such that the closed-loop system is stable and satisfies H2 performance for all admissible uncertainties. Furthermore, the solution of the controller is given. An H2 output feedback controller is designed in the airborne dispenser pitch channel, and the simulation results show that the controller is effective.

Effect of Autopilot Structure on Proportional Navigation Guidance

XIA Qun-li, LIU Yi-ying, QI Zai-kang

2007, 16(2): 177-181.

[Abstract](191)

Abstract:
The dynamic characteristics of acceleration autopilot and attitude autopilot are discussed in detail. Also, a comparison study was made between these two different types of control schemes for guidance loop. By means of simulation, it is concluded that the guidance accuracy is mainly determined by the slowest subsystem among different system dynamics. For air-to-ground missiles, with limited terminal guidance time, the control scheme of acceleration autopilot combined with proportional navigation guidance (PNG) law is the better choice.

Study of Asymmetric Polling System with Two Message Classes

CAO Chun-sheng, ZHANG Wei-dong

2007, 16(2): 182-186.

[Abstract](103)

Abstract:
A novel mixed polling system with multiple stations is considered. Each station produces two classes of messages served with different disciplines. The real time message served with exhaustive service discipline and the unreal time message served with gated service discipline. Using an iterative method, the exact mean waiting times for both message classes are derived. The influence of the gate location of the message class served by the gated service discipline on the mean waiting time is also analyzed. The analytical results are verified with simulation method and agree well with simulation results.

Variable Rate Characteristic Waveform Interpolation Speech Coder Based on Phonetic Classification

WANG Jing, KUANG Jing-ming, ZHAO Sheng-hui

2007, 16(2): 187-192.

[Abstract](181)

Abstract:
A variable-bit-rate characteristic waveform interpolation (VBR-CWI) speech codec with about 1.8 kbit/s average bit rate which integrates phonetic classification into characteristic waveform (CW) decomposition is proposed. Each input frame is classified into one of 4 phonetic classes. Non-speech frames are represented with Bark-band noise model. The extracted CWs become rapidly evolving waveforms (REWs) or slowly evolving waveforms (SEWs) in the cases of unvoiced or stationary voiced frames respectively, while mixed voiced frames use the same CW decomposition as that in the conventional CWI. Experimental results show that the proposed codec can eliminate most buzzy and noisy artifacts existing in the fixed-bit-rate characteristic waveform interpolation (FBR-CWI) speech codec, the average bit rate can be much lower, and its reconstructed speech quality is much better than FS 1 016 CELP at 4.8 kbit/s and similar to G.723.1 ACELP at 5.3 kbit/s.

Bistatic Synthetic Aperture Radar Point Spread Function Characteristic Analysis

HU Cheng, ZENG Tao, ZENG Hai-bin

2007, 16(2): 193-196.

[Abstract](239)

Abstract:
Based on the point spread function (PSF) theory, the side-lobe extension direction of the impulse response in bistatic synthetic aperture radar (BSAR) is analyzed in detail; in addition, the corresponding auto-focus in BSAR should be considered along iso-range direction, not the traditional azimuth resolution (AR) direction. The conclusion is verified by the computer simulation.

Novel Sequential Neural Network Learning Algorithm for Function Approximation

KANG Huai-qi, SHI Cai-cheng, HE Pei-kun, LI Xiao-qiong

2007, 16(2): 197-200.

[Abstract](163)

Abstract:
A novel sequential neural network learning algorithm for function approximation is presented. The multi-step-ahead output predictor of the stochastic time series is introduced to the growing and pruning network for constructing network structure. And the network parameters are adjusted by the proportional differential filter (PDF) rather than EKF when the network growing criteria are not met. Experimental results show that the proposed algorithm can obtain a more compact network along with a smaller error in mean square sense than other typical sequential learning algorithms.

Range Ambiguity Elimination in a Short-Range FMCW Radar System

WEI Guo-hua, WU Si-liang

2007, 16(2): 201-204.

[Abstract](243)

Abstract:
Modified implementation architecture for sinusoidal frequency modulation is introduced to extract the range information from the received radar echo. Range ambiguity problem arises because the range is calculated from the estimated phase of the received signal which is wrapped into (0,2π]. By integrating Doppler frequency shifts, the variation of range can be estimated and used as an auxiliary information to help eliminating the corresponding range ambiguity. The performance of the new technique is evaluated by simulations. The results show that this technique is robust to sever phase noise and can be used effectively for ambiguity elimination of the modified sinusoidal frequency modulated continuous wave radar.

Main Factors for Affecting Photonic Bandgap of Photonic Crystals

LI Xia, XUE Wei, JIANG Yu-rong, YU Zhi-nong, WANG Hua-qing

2007, 16(2): 205-210.

[Abstract](188)

Abstract:
The factors affecting one dimensional (1D) and two dimensional (2D) photonic crystals (PhCs) are systemically analyzed in this paper by numerical simulation. Transfer matrix method (TMM) is employed for 1D PCs, both finite difference time domain method (FDTD) and plane wave expansion method (PWE) are employed for 2D PCs. The result shows that the photonic bandgaps (PBG) are directly affected by crystal type, crystal lattice constant, modulation of refractive index and periodicity, and it is should be useful for design of different type photonic crystals with the required PBG and functional devices. Finally, as an example, a near-IR 1D PCs narrow filter was designed.

Research on Penetration Rules of LY-12cz Thin Sheet Subjected to Rod-Shaped Fragment

PAN Qing-jun, SONG Li-ru, HUANG Zao-wen, XIONG La-sen

2007, 16(2): 211-216.

[Abstract](193)

Abstract:
By establishing the finite element models and corresponding calculation methods for the target board and rod-shaped fragment, the penetration effect of the high-velocity rod-shaped fragments' impact on the LY-12cz thin sheet is analyzed by analog calculation. The variation rules of the residual velocity and residual mass of fragments, chock mass and crevasse shape are obtained when the fragment penetrates target board with different incidence velocities and attack angles. Corresponding fitting computation formulas are concluded from the above calculating data. The conclusions are helpful to analyzing the destructivity of fragment and protective ability of aircraft structure. In addition, they can guide the research for battle damage mode and assessment effectively.

Nitration of Phenol Catalyzed by Horseradish Peroxidase

DAI Rong-ji, HUANG Hui, TONG Bin, XIAO Sheng-yuan

2007, 16(2): 217-219.

[Abstract](81)

Abstract:
Horseradish peroxidase, an acidic peroxidase from the horseradish, is one of the most important enzymes as analytical reagent. The enzymatic nitration of phenol by oxidation of nitrite was studied using horseradish peroxidase in the presence of H2O2. The results showed that nitration occur at 2- and 4- positions of phenol. There were also minor products of hydroquinone and catechol. The influence of various reaction parameters, including pH, organic solvent, and concentration of H2O2, on nitration products were discussed. The best nitration pH was 7.0, and H2O2 should be added to the reaction mixture slowly.

Cytological Effects of Space Environment on Different Genotype of Rice

WEI Li-jun, QIAN Yu, YANG Qian, XU Jian-long, WANG Jun-min, SUN Ye-qing

2007, 16(2): 220-225.

[Abstract](209)

Abstract:
For exploring the biological effect of space environment on different genotype of rice seeds, the cytological effects of M1 generation after space flight were studied. Twelve different genotypes of rice seeds which belong to different climate ecotype (early, medium and late) of indica and japonica were onboard “Shenzhou 4” spaceship for 162 h. After recovered the total number of mitosis cells and chromosomal aberration were observed. In all the lines the mitotic index (MIs) of space flight are much higher than control, which indicates the stimulate effect of space environment. The cell rate of chromosomal aberration (CRCA) of space flight is also much higher than control, but varies from line to line. It indicates that biological effect of space environment on rice seed dependents not only on flight duration but also on rice genotype. The radiosensitivities of different lines were also discussed according to CRCAs.

Calculation and Analysis of Mean Opacity of Gold Mixtures

YAN An-ying, JIANG Ming, CHENG Xin-lu, YANG Xiang-dong

2007, 16(2): 226-230.

[Abstract](166)

Abstract:
A screened hydrogenic model for l splitting (SHML) is used to calculate the Rosseland mean opacities of high-Z Au, Ta, Yb, Ho, Gd, Sm, Nd, Sn, Ag plasmas and mixtures of gold and these elements at high temperature (T=200-400 eV) and dense (ρ=1 g/cm3). From the calculated Rosseland mean opacities of the mixtures, Au-Nd seems to be a better choice than other mixtures. Simultaneously, the reason that the mean opacities of mixture of Au-Sn decrease slightly when T=400 eV is analyzed.

Parallel Machine Scheduling Models with Fuzzy Parameters and Precedence Constraints: A Credibility Approach

HOU Fu-jun, WU Qi-zong

2007, 16(2): 231-236.

[Abstract](188)

Abstract:
A method for modeling the parallel machine scheduling problems with fuzzy parameters and precedence constraints based on credibility measure is provided. For the given n jobs to be processed on m machines, it is assumed that the processing times and the due dates are nonnegative fuzzy numbers and all the weights are positive, crisp numbers. Based on credibility measure, three parallel machine scheduling problems and a goal-programming model are formulated. Feasible schedules are evaluated not only by their objective values but also by the credibility degree of satisfaction with their precedence constraints. The genetic algorithm is utilized to find the best solutions in a short period of time. An illustrative numerical example is also given. Simulation results show that the proposed models are effective, which can deal with the parallel machine scheduling problems with fuzzy parameters and precedence constraints based on credibility measure.

Improved Group Fuzzy Preference Programming Method Based on Fuzzy Random Theory

HUANG Li-jian, WU Qi-zong

2007, 16(2): 237-242.

[Abstract](219)

Abstract:
A new prioritization method in the analytic hierarchy process (AHP), which improves the group fuzzy preference programming (GFPP) method, is proposed. The fuzzy random theory is applied in the new prioritization method. By modifying the principle of decision making implied in the GFPP method, the improved group fuzzy preference programming (IGFPP) method is formulated as a fuzzy linear programming problem to maximize the average degree of the group satisfaction with all possible group priority vectors. The IGFPP method inherits the advantages of the GFPP method, and solves the weighting trouble existed in the GFPP method. Numerical tests indicate that the IGFPP method performs more effectively than the GFPP method in the case of very contradictive comparison judgments from decision makers.

Investigation Into the Market-Orientated New Product Development Performance

WANG Xiu-cun, LU Bin-bin

2007, 16(2): 243-247.

[Abstract](74)

Abstract:
The effect that the market orientation brings to product innovation performance is reported and the degree of product innovativeness is explored. The interdepartmental integration inside the company is also investigated. A series of hypotheses were developed aiming at presenting a conceptual framework to clarify how market orientation contributes to product innovation performance-moderated by the degree of product innovativeness and affected by the interdepartmental integration. Survey data from 36 business units were analyzed based on the respondents in the research. The statistic results suggest a substantial positive effect of market orientation on product innovation performance. Under the condition of incremental innovativeness among the samples, the more innovative the product is, the more improvements in product innovation performance would be achieved. A variety of particular interdepartmental integration mechanisms have been certified to lend more supports to establishing market orientation and improving product innovation performance.

Real Estate in Chongqing as a Pillar Industry: A Quantitative Analysis

XIANG Wei-min, REN Hong

2007, 16(2): 248-252.

[Abstract](84)

Abstract:
The definition of pillar industry is stated and its indicators, including the proportion of added value in the GDP, the degree of industry correlation, the income elasticity of demand, and the growth rate of employment will be discussed. And then index weighing is determined based on the degree of importance. The result of the quantitative analysis of real estate industry in Chongqing suggests that its first three evaluating indicators live up to the index requirement of a pillar industry while its degree of industry correlation is not satisfactory. An overall evaluation indicates that the real estate industry in Chongqing meets the requirements of pillar industry.

2007 Vol. 16, No. 2