JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

3D Numerical Simulation of Projectile Penetration into Concrete Target

2008, 17(4): 379-383.

[Abstract](183)

Abstract:
Basing on the explicit instantaneous dynamics software MSC-Dytran and the general coupling arithmetic, the process of the projectile penetration into concrete target was simulated with the point-line-surface-body modeling method. Simulation results are in agreement with experimental results. The simulated data could provide design reference for the defense engineering construction and penetrator design.

Numerical Simulation on Explosion in Double-Layer Medium of Concrete and Soil

LIU Yan, HUANG Feng-1ei, ZHANG Zhen-yu

2008, 17(4): 384-387.

[Abstract](203)

Abstract:
The numerical simulation on explosion in concrete and soil is performed by using the three-dimension finite element code LS-DYNA, into which a continuum damage model which can well describe the fracture of concrete is implemented. As a consequence, wave propagation and attenuation in concrete and on soil-concrete interface are obtained respectively. Moreover, the damage regions of concrete at different thicknesses of soil (TOS) and depths of charge (DOC) are procured. The existent soil reduces damage region of concrete. Numerical results provide reference for design of warhead and protective structure and blasting.

Flexible Developing System for Modern Instrument Manufacturing

XU Xiao-li, ZUO Yun-bo, WU Guo-xin

2008, 17(4): 388-394.

[Abstract](173)

Abstract:
The modern instrument manufacturing has many features, such as high technologies, multiple varieties and small quantities. Aiming at those features, an instrumentation flexible developing system (IFDS) is presented. It constitutes a kind of opening, compatible, extensible and upgradeable flexible developing system, and it will offer a kind of technology equipment for the research and development of new modern instrument products. Its flexible mechanism is able to be suited for different and special requirements of many instrument systems, and its system integrated mechanism is able to adapt to common technological features of most instrument systems. It is IFDS that makes it easy to accomplish a quick system integration of instrument products. IFDS solves key technological problems related to modern instruments development, develops multiple systems for modern instrument development and accomplishes rapid development of series of new products.

Auto-Test on Motor Temperature Rising in Electric Vehicles with Mutual MRAS

WANG Zhi-fu, ZHANG Cheng-ning

2008, 17(4): 395-399.

[Abstract](321)

Abstract:
A new method to calculate the motor temperature rising in electric vehicle (EV) is proposed based on the stator resistance identification. The measure theory of the motor temperature rising with the stator resistance is discussed at first. An enhanced magnetism motor dynamic math model is built which is the research object. Then the resistance identification system model is built on the mutual model reference adaptive system (MRAS) theory. The simulation diagram of the mutual MRAS model is constructed and the resistance identification performance is studied in different motor states. Simulation results indicate that the stator resistance identification model with the mutual MRAS is effective. At the same time, the identification of motor temperature rising is possible with the identification of the stator resistance.

Active Noise Control of the Heavy Truck Interior Cab

LI Hui-bin, LIU Hai-guang, LIU Ji-chun, SHANG GUAN Yun-fei

2008, 17(4): 400-404.

[Abstract](250)

Abstract:
Abstract：In order to control the noise of the heavy truck interior cab effectively， the active noise contro1 methods are employed．First，an interior noise field test for the heavy truck is performed，and frequencies of interior noise of this vehicle are analyzed．According to the spectrum analysis of acquired noise signal，it is found out that the main frequencies of interior noise are 1ess than 800Hz．Then the least squares lattice(LSL) algorithm is used as signal processing algorithm of the controller and a closed—lop control DSP system，based on TMS 320VC5416，is developed．The residual signal at driver’s ear is used as feedback signa1．Lastly，the developed ANC system is loaded into the heavy truck cab，and controlling the noise at driver’s ear for that truck at different driving speeds is attempted．The noise control test results indicate that the cab interior noise is reduced averagely by 0．9 dBA at different driving speeds．

Research on Drag Torque Prediction Model for the Wet Clutches

HU Ji-bin, JING Chong-bo, PENG Zeng-xiong, WANG Bin

2008, 17(4): 405-409.

[Abstract](242)

Abstract:
Considering the surface tension effect and centrifugal effect, a mathematical model based on Reynolds equation for predicting the drag torque of disengage wet clutches is presented. The model indicates that the equivalent radius is a function of clutch speed and flow rate. The drag torque achieves its peak at a critical speed. Above this speed, drag torque drops due to the shrinking of the oil film. The model also points out that viscosity and flow rate effects on drag torque. Experimental results indicate that the model is reasonable and it performs well for predicting the drag torque peak.

Size Distribution of Particles Emitted from Liquefied Natural Gas Fueled Engine

WANG Jun-fang, GE Yun-shan, HE Chao, TAN Jian-wei, YOU Ke-wei

2008, 17(4): 410-414.

[Abstract](138)

Abstract:
The results of measurements conducted to determine the number and mass concentration of particles emitted from the liquefied natural gas (LNG) fueled spark ignition engines are presented. Particle size distributions were measured at different speeds, different loads and ESC cycles. The nanoparticles with diameter smaller than 39nm, measured by the electrical low-pressure impactor (ELPI), are dominant in number concentration that is nearly 92.7% of the total number of the emitted particles at the peak point. As for the mass of emission particle, it is shown that the mass of the particles greater than 1.2μm is more than 65% that of the emitted particles.

Improved Multicast Protocol Based on Routing Grid

ZHANG Quan-xin, NIU Zhen-dong, JIN Fu-sheng, FAN Xiu-mei, YUAN Da

2008, 17(4): 415-418.

[Abstract](127)

Abstract:
Problems may occur in ad hoc network when packets are being multicast. Global routing structure may also produce extra processing cost because the dynamic topology will introduce frequent exchange of routing vector or routing state between nodes. To deal with these problems an improved multicast protocol based on routing grid is designed to ensure that the multicast packets could be sent to destination through dynamic topology network using multicast routing grid.

Mechanism Modeling and Simulation Based on Dimensional Deviation

WANG Ya-bin, LIU Ming-jie, TAN Hui-min

2008, 17(4): 419-422.

[Abstract](155)

Abstract:
To analyze the effects on motion characteristics of mechanisms of dimensional variations, a study on random dimensional deviation generation techniques for 3D models on the basis of the present mechanical modeling software was carried out, which utilized the redeveloped interfaces provided by the modeling software to develop a random dimensional deviation generation system with certain probability distribution characteristics. This system has been used to perform modeling and simulation of the specific mechanical time delayed mechanism under multiple deviation varieties, simulation results indicate the dynamic characteristics of the mechanism are influenced significantly by the dimensional deviation in the tolerance distribution range, which should be emphasized in the design.

Research and Implementation of Algorithm for Image Enhancement and Unwrapped Distortion Correction for SLVF Panoramic Night Vision Image

ZHANG Zhen-hai, LI Ke-jie, GAO Jun-xiao, DUAN Xing-guang

2008, 17(4): 423-428.

[Abstract](308)

Abstract:
Based on digital signal processor(DSP) and field programmable gate array(FPGA) techniques, the architecture of super large view field(SLVF) panoramic night vision image processing hardware platform was established. The panoramic unwrapping and correcting algorithm, up to a full 360°, based on coordinate rotation digital computer (CORDIC) and night vision image enhancement algorithm, based on histogram equalization theory and edge detection theory, was presented in this paper, with the purpose of processing night vision dynamic panoramic annular image. The annular image can be unwrapped and corrected to conventional rectangular panorama by the panoramic image processing algorithm, which uses the pipelined CORDIC configuration to realize a trigonometric function generator with high speed and high precision. Histogram equalization algorithm can perfectly enhance the contrast of the night vision image. Edge detection algorithm can be propitious to find and detect small dim dynamic targets in night vision circumstances. After abundant experiment, the algorithm for panoramic image processing and night vision image enhancement is successfully implemented in FPGA and DSP. The panoramic night vision image system is a compact device, with no external rotating parts. And the system can reliably and dynamically detect 360° SLVF panoramic night vision image.

Dynamics Modeling of Heavy Special Driving Simulator

WANG Jian-zhong, TANG Yi, ZHANG Xue-ling, LI Hong-zhe

2008, 17(4): 429-433.

[Abstract](167)

Abstract:
Based on the dynamical characteristic parameters of the real vehicle, the modeling approach and procedure of dynamics of vehicles are expatiated. The layout of vehicle dynamics is proposed, and the sub-models of the diesel engine, drivetrain system and vehicle multi-body dynamics are introduced. Finally, the running characteristic data of the virtual and real vehicles are compared, which shows that the dynamics model is similar closely to the real vehicle system.

Adaptive Kalman Filter of Transfer Alignment with Un-modeled Wing Flexure of Aircraft

ZHOU Feng, MENG Xiu-yun

2008, 17(4): 434-438.

[Abstract](222)

Abstract:
The alignment accuracy of the strap-down inertial navigation system (SINS) of airborne weapon is greatly degraded by the dynamic wing flexure of the aircraft. An adaptive Kalman filter uses innovation sequences based on the maximum likelihood estimated criterion to adapt the system noise covariance matrix and the measurement noise covariance matrix on line, which is used to estimate the misalignment if the model of wing flexure of the aircraft is unknown. From a number of simulations, it is shown that the accuracy of the adaptive Kalman filter is better than the conventional Kalman filter, and the erroneous misalignment models of the wing flexure of aircraft will cause bad estimation results of Kalman filter using attitude match method.

Motion Planning of Humanoid Robot for Obstacle Negotiation

JAFRI Ali Raza, HUANG Qiang, YANG Jie, ZHAG Wei-min

2008, 17(4): 439-444.

[Abstract](148)

Abstract:
The motion planning for obstacle negotiation by humanoid robot BHR-2 through stepping over or stepping on/off the wide and flat obstacle at known locations is presented. In the trajectory generation method, first the constraints of the foot motion parameters which include obstacle dimensions and the distance of obstacle from the humanoid robot is formulated. By varying the values of the constraint parameters, different types of foot motion for different obstacles can be produced. In this method, first the foot trajectory is generated, and then the waist trajectory is computed by using cubic spline interpolation without first calculating the zero moment point (ZMP) trajectory . The dynamic stability during the execution of stepping over and stepping on/off trajectories are ensured by incorporating the ZMP criterion. The effectiveness of the proposed method is confirmed by simulations and experiments on humanoid robot BHR-2.

Fuzzy Logic Supervised Teleoperation Control for Mobile Robot

RAHMAN Nasir, HUANG Qiang, LI Jing-tao, ZENG Zhi, LI Ke-jie

2008, 17(4): 445-450.

[Abstract](207)

Abstract:
The supervised teleoperation control is presented for a mobile robot to implement the tasks by using fuzzy logic. The teleoperation control system includes joystick based user interaction mechanism, the high level instruction set and fuzzy logic behaviors integrated in a supervised autonomy teleoperation control system for indoor navigation. These behaviors include left wall following, right wall following, turn left, turn right, left obstacle avoidance, right obstacle avoidance and corridor following based on ultrasonic range finders data. The robot compares the instructive high level command from the operator and relays back a suggestive signal back to the operator in case of mismatch between environment and instructive command. This strategy relieves the operator's cognitive burden, handle unforeseen situations and uncertainties of environment autonomously. The effectiveness of the proposed method for navigation in an unstructured environment is verified by experiments conducted on a mobile robot equipped with only ultrasonic range finders for environment sensing.

On Fibre Bundle Surfaces and Their Curvatures

LI Fang-xing, PENG Lin-yu, SUN Hua-fei

2008, 17(4): 451-454.

[Abstract](70)

Abstract:
A surface model called the fibre bundle model is proposed. This model represents a surface locally as a direct product of two curves: a base curve and a fibre curve. We introduce the fibre bundle model and then obtain the Gaussian curvatures and the mean curvatures of a certain kind of fibre bundle surface models using 1-parameter groups of a linear Lie algebra as fibres. Some examples are given to verify our results.

Subpixel Reconstruction Algorithm in Staring FPA Nonuniform Microscan Imaging

CHEN Yi-nan, JIN Wei-qi, ZHAO Lei, ZHAO Lin

2008, 17(4): 455-461.

[Abstract](223)

Abstract:
For the nonuniform microscan system where the interframe translation is no longer equivalent to accurate halfpixel, a 2-dimension non-interpolated subpixel algorithm is proposed to consider arbitrary value of microscanning. The aim of the proposed algorithm is to restore double resolution from 2×2 undersampled frames. To solve the ill-posed problem in the process of image reconstruction, the prior boundary condition is introduced, and the proposed subpixel reconstruction algorithm is reformulated into the form of line-by-line backward propagation iteration for reducing the calculation complexity. Since the direction of movement offset relative to the accurate halfpixel determines the transfer matrix of the image degradation process, the reconstruction is classified into 4 types when 2×2 microscan model is applied. All the simulation results and experiment data demonstrate the double resolution improvement compared with the undersampled images. The focus problem, scarcely any possibility of the operation with accurate halfpixel micromotion, is figured out for enhancing the feasibility of subpixel reconstruction used in practice.

Research of Frequency Discriminator on Frequency Lock Loops

XU Ying, WU Si-liang, WANG Ju

2008, 17(4): 462-465.

[Abstract](199)

Abstract:
Frequency lock loops (FLL) discriminating algorithms for direct-sequence spread-spectrum are discussed. The existing algorithms can't solve the problem of data bit reversal during one pre-detection integral period. And when the initial frequency offset is large, the frequency discriminator can't work normally. To solve these problems, a new FLL discriminating algorithm is introduced. The least-squares discriminator is used in this new algorithm. As the least-squares discriminator has a short process unit period, the corresponding frequency discriminating range is large. And the data bit reversal just influence one process unit period, so the least-squares discriminated result will not be affected. Compared with traditional frequency discriminator, the least-squares algorithm can effectively solve the problem of data bit reversal and can endure larger initial frequency offset.

Fast Computation of Cross-Ambiguity Function

ZHUO Zhi-hai, SHAN Tao, TAO Ran

2008, 17(4): 466-471.

[Abstract](261)

Abstract:
A novel method based on zoom fast Fourier transform(FFT) is proposed for minimizing the burden processing of cross-ambiguity functions without affecting performance. The low-pass anti-aliasing filter in zoom FFT is realized by using the multistage filtering technique and the weighting processing is employed in the first stage filter to get rid of the redundancy of the computation. In practical systems, the input data is divided into overlapped data frames to avoid loss of detection ability which results in the rapid increase of computational complexity. A segment technique is also proposed in which CAF calculation of overlapped data frames is viewed as slide window FFT to decrease the computational complexity. The experimental results show that compared to the conventional methods, the proposed method can lower computational complexity and is consistent with the real time implementation in existing high-speed digital processors.

Improved Spectral Representation for Birdcall Based on Fractional Fourier Transform

YIN Hui, XIE Xiang, KUANG Jing-ming

2008, 17(4): 472-477.

[Abstract](210)

Abstract:
A novel spectral representation based on fractional Fourier transform (FrFT) is proposed and applied to birdcall analysis. The FrFT-based spectrogram of a signal is derived and compared with its FT-based counterpart, and the spectrum gathering method is used to show the energy distribution related to the pitch frequency. The fixed transform order and adaptive orders for FrFT are tested. The fixed order can be obtained empirically or calculated according to the known chirp rate. The adaptive optimal orders are determined by using ambiguity function. Experimental results with birdcalls show that the FrFT-based spectrogram with an optimal transform order has higher resolution than its STFT-based counterpart, and the better performance can be achieved if adaptive orders are used.

Novel Facial Features Segmentation Algorithm

JIANG Wei, SHEN Ting-zhi, WANG Xiao-hua, ZHANG Jian

2008, 17(4): 478-483.

[Abstract](255)

Abstract:
An efficient algorithm for facial features extractions is proposed. The facial features we segment are the two eyes, nose and mouth. The algorithm is based on an improved Gabor wavelets edge detector, morphological approach to detect the face region and facial features regions, and an improved T-shape face mask to locate the extract location of facial features. The experimental results show that the proposed method is robust against facial expression, illumination, and can be also effective if the person wearing glasses, and so on.

Wavelet Packet Domain LMS Based Multi-User Detection

LIU Peng, AN Jian-ping

2008, 17(4): 484-488.

[Abstract](184)

Abstract:
An improved wavelet packet domain least mean square (IWPD-LMS) based adaptive multiuser detection algorithm is proposed. The algorithm employs the wavelet packet transform to re-whiten the input data, and chooses the best wavelet packet basis according to a novel convergence contribution function rather than the conventional Shannon entropy. The theoretic analyses show that the inadequacy of the eigenvalue spread of the tap-input correlation matrix is ameliorated, thus the convergence performance is improved greatly. The simulation result of convergence performance and bit error rate(BER) performance as a function of the signal power to noise power ratio(SNR) are presented finally to prove the validity of the proposed algorithm.

Bioleaching of Nickel and Cobalt from Spent Nickel Metal Hydride Batteries by Acidithiobacilli spp

WU Feng, SUN Yan, XIN Bao-ping, LI Li

2008, 17(4): 489-494.

[Abstract](118)

Abstract:
The Acidithiobacillus ferrooxidans(At.f) and Acidithiobacillus thiooxidans (At.t) were used in bio-dissolution experiments of heavy metals in spent MH/Ni batteries. The influences of the initial pH value, the concentration of electrode materials, the temperature and substrate concentration on the leaching rate of heavy metal Ni, Co have been investigated. The obtained results indicate that the efficiency of nickel extraction and cobalt extraction is dependent on all of the mentioned factors. Especially, the initial pH value and the temperature have more effect than other factors for these microorganisms. In addition, the results show that the optimal leaching rate of Ni and Co in the spent MH/Ni batteries reaches to 95.7% and 72.4% respectively after 20 days under the conditions of the initial pH value 1.0, concentration of electrode materials 1.0%, temperature 30℃ and substrate(sulfur) concentration 4.0g·L-1.

Optimization Method for Indoor Thermal Comfort Based on Interactive Numerical Calculation

XU Yuan-qing, CHEN Xiang-guang, ZHANG Chun-cheng

2008, 17(4): 495-500.

[Abstract](188)

Abstract:
In order to implement the optimal design of the indoor thermal comfort based on the numerical modeling method, the numerical calculation platform is combined seamlessly with the data-processing platform, and an interactive numerical calculation platform which includes the functions of numerical simulation and optimization is established. The artificial neural network (ANN) and the greedy strategy are introduced into the hill-climbing pattern heuristic search process, and the optimizing search direction can be predicted by using small samples; when searching along the direction using the greedy strategy, the optimal values can be quickly approached. Therefore, excessive external calling of the numerical modeling process can be avoided,and the optimization time is decreased obviously. The experimental results indicate that the satisfied output parameters of air conditioning can be quickly given out based on the interactive numerical calculation platform and the improved search method, and the optimization for indoor thermal comfort can be completed.

Erythrocyte-Like Mg(OH)2 Microspheres Self-Assembled by Nanocrystallites

LONG Xu, GUO Lin, LI Qian-shu

2008, 17(4): 501-504.

[Abstract](75)

Abstract:
The erythrocyte-like magnesium hydroxide microspheres were synthesized in large scale through a simple solution phase route. The structures and morphologies of the products were analyzed by the X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM). The possible growth mechanism of the nanostructure was discussed briefly and the potential application was proposed.

2008 Vol. 17, No. 4