JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Further Study on a Virtual Age Repair Model

CHEN Gong, SUN Qing, CUI Li-rong

2010, 19(4)

[Abstract](601) [PDF 270KB](278)

Abstract:
A new virtual age repair model with non-uniform aging speed is presented on the basis of Kijima classical virtual age repair models which can be viewed as of uniform aging nature. In this model are included three types, of perfect, of imperfect and of minimal, all having a non-uniform aging speed. Formulas of expected count of repair and length of working time of these three models are derived, and numerical examples are also given to illustrate and verify obtained theoretical indices. As an extended work, a sketchy model of maintenance time of the non-uniform aging virtual age repair model is discussed. Overall, the three models discussed in the paper, each with non-uniform aging speed, are expansions to existing virtual age repair models, relevant formulas given here are new results, and the systems introduced are without the lifetime distribution assumption, all of which may be expected to improve maintenance work.

Optimal Parameters for Pricing of the American Put Options with Least Square Monte Carlo Simulation

HOU Nai-cong, ZHANG Guan-li

2010, 19(4): 499-502.

[Abstract](6272) [PDF 280KB](624)

Abstract:
Pricing the American put options requires solving an optimal stopping problem and therefore is a challenge for the setting up of simulation parameters. This paper uses least square Monte Carlo (LSMC) simulation to price the American put options and output the optimal simulation steps and number of Hermite basis functions. The results suggest: with different time cost and error tolerance, investors can choose the optimal simulation steps and number of basis function individually to price American put options numerically. Generally, with the pre-limitation in the section "least square Monte Carlo simulation", a number of basis equals 4, 15 000 simulation steps for Hermite basis function appear to be sufficient for the method.

Diffusive Wave Model and Its Applications to Biology and Physics

FAN Tian-you, FAN Lei

2010, 19(4): 379-381.

[Abstract](759) [PDF 228KB](325)

Abstract:
This study presents the diffusive wave model, relevant dispersion law and the applications to the signal transduction of live cells, phason dynamics of quasicrystals, Brownian movement, electro-magnetic field and fluid dynamics fluctuation, respectively. The common features of these diffusive waves are summarized, which present diffusion as well as wave behaviour, or exactly speaking, they present a duality of diffusion and wave or the duality of wave and diffusion. Furthermore, the general nature of the motion is discussed from the point of view of Landau elementary excitation of condensed matter, this may lead to a concept of generalized elementary excitation (or generalized quasiparticle) corresponding to the diffusive wave.

Dynamic Shear Stress Measurements of PMMA

DUAN Zhuo-ping, OU Zhuo-cheng, CAI Shao-jia, HUANG Feng-lei

2010, 19(4): 382-385.

[Abstract](734) [PDF 281KB](288)

Abstract:
In this paper, experiments of one-dimensional plane plate impact on polymethylmethacrylate (PMMA) targets are conducted, in which dynamic transverse stresses induced in the targets are measured using a new type of manganin piezoresistive stress gauge having 50 Ω low-pressure narrow grid-like foil. It is shown that this new instrument can improve measurement accuracy remarkably by reducing the so-called strain effect. Moreover, relationship between shear stress and longitudinal stress within a certain range of the latter is obtained.

Full Digital Smart Fuze on Air Target

PAN Xi, CUI Zhan-zhong

2010, 19(4): 386-389.

[Abstract](795) [PDF 279KB](367)

Abstract:
The intelligent fuzing is a kind of perfect way to optimize detonation location. The fuze can autonomously configure the warhead detonation mode to optimize the desired effects against the target. For the air target, the fuze can sense the impact in the impact mode then detonate the warhead on impact, otherwise, it will operate in the proximity mode and detonate at a closest approach to the target. The anti-jamming ability is also added on fuze’s full digital signal processing platform. The method for burst point’s controlling is analyzed and the digital intelligent fuze system based on system on programmable chip (SOPC) is designed.

Compressional Punch Loading Test of a Polymer Bonded Explosive Simulant Using Digital Image Correlation Method

ZHOU Zhong-bin, CHEN Peng-wan, HUANG Feng-lei, LIU Si-qi

2010, 19(4): 390-394.

[Abstract](673) [PDF 434KB](260)

Abstract:
Punch loading is a loading scenario to study the fracture mechanism of materials at low strain rates. In this paper, three punch loading experimental patterns were chosen for the study of compressional punch loading. A polymer bonded explosive (PBX) simulant was experimentally studied using the digital image correlation (DIC) method. The displacement and strain fields were obtained and the fracture behavior and failure mechanisms of samples were investigated under different punch loading conditions. Moreover, scanning electron microscope (SEM) was used to examine the region of the plastic flow and the damage in the material. The formation of slip bands, shear displacement and fracture of the hard phase particle, were observed on the boundary of the dead zone due to the large shear strains.

Analysis Model on Penetration Depth of Concrete by Eroding Long-Rod Projectiles

LIAN Bing, JIANG Jian-wei, MEN Jian-bing, WANG Shu-you

2010, 19(4): 395-398.

[Abstract](767) [PDF 280KB](296)

Abstract:
Mass loss should be considered while calculating the penetration depth of concrete by eroding long-rod projectiles of high velocity. The penetration process is divided into two phases: eroding phase and rigid phase. During eroding phase, a model to predict the penetration depth is established on the assumption that there is a chipping region in the bottom of crater. During rigid phase, Forrestal formula is adopted to calculate the penetration depth. Using this model, the depth of concrete penetration by a tungsten alloy long-rod projectile is calculated. When the critical eroding velocity is between 950 m/s and 1 000 m/s, the result is in good agreement with the experimental data.

Confinement Effect and Diameter Effect on the Non-ideal Detonation Parameters of Small Charge

XU Xin-chun, JIAO Qing-jie, JIN Zhao-xin, YANG Gui-li

2010, 19(4): 399-404.

[Abstract](809) [PDF 317KB](251)

Abstract:
An expanding model of the confinement of non-ideal detonation of small charge is established on the basis of the nozzle theory. Making use of the expanding model, the analytic relationship of small charge detonation velocity and the semi-empirical relationship of detonation pressure that both change with charge diameter and confinement condition are established. The detonation velocity and pressure of small charges are calculated and experimentally verified, and the detonation velocity deviation is less than 7% while the detonation pressure deviation is less than 9%.

AMT-Fault-Diagnosis Device Based on ISO 15765

XI Jun-qiang, XIAO Kuan, YANG Ai-jun

2010, 19(4): 405-410.

[Abstract](1018) [PDF 317KB](383)

Abstract:
To debug automatic mechanical transmission (AMT) more quickly and accurately, an AMT-fault-diagnosis device is designed based on the ISO 15765 protocol, which adopts the flow control mechanism and has off-line diagnostics function. Requirements for the device are analyzed and diagnostic trouble code (DTC) is defined. Electrically controlled hardware with graphics display function and fault diagnostic software flowchart are designed based on the electronic control hydraulic AMT system. Bench and vehicle driving tests showethat the AMT-fault-diagnosis device can read and delete the fault message successfully with a stable performance.

Bending-Torsional Coupled Vibration Test of Large Power Gear Transmission System

LIU Hui, XIANG Chang-le, SUN Tian-tian, CAI Zhong-chang

2010, 19(4): 411-415.

[Abstract](608) [PDF 308KB](256)

Abstract:
In order to test the bending-torsional coupled vibration characteristics of the multi-shafts gear transmission system of large power vehicles, a torsional vibration exciter was used to apply torsional excitation on the gear transmission systems and thirty-two acceleration sensors were used to measure the tangential acceleration of each shaft. Torsional vibration signals and bending vibration signals of each measuring point were obtained by calculation of the four-point-response signal. The modal parameters of gear transmission systems including nature frequency, modal shape and modal damping ratio were obtained by identifying modal parameters of the torsional vibration signal and bending vibration signal. The characteristic of the bending vibration and torsional vibration of the gear systems were studied through the analysis of the nature frequency and modal shape. The nonlinearity characteristic of the gear transmission system was investigated through single frequency excitation test, which can be the foundation for further nonlinearity research.

Fuzzy Model for Estimation of the State-of-Charge of Lithium-Ion Batteries for Electric Vehicles

HU Xiao-song, SUN Feng-chun, CHENG Xi-ming

2010, 19(4): 416-421.

[Abstract](703) [PDF 359KB](257)

Abstract:
A fuzzy model was established to estimate the state of charge (SOC) of a lithium-ion battery for electric vehicles. The robust Gustafson-Kessel (GK) clustering algorithm based on clustering validity indices was applied to identify the structure and antecedent parameters of the model. The least squares algorithm was utilized to determine the consequent parameters. Validation results show that this model can provide accurate SOC estimation for the lithium-ion battery and satisfy the requirement for practical electric vehicle applications.

Research on the Initial Ignition of the Underwater Launching Solid Rocket Motor

MA Yan-li, JIANG Yi, HAO Ji-guang, LIU Bo-wei

2010, 19(4): 422-426.

[Abstract](6236) [PDF 356KB](1111)

Abstract:
The aim of this investigation is to research the initial ignition of the underwater-launching solid rocket motor. The MIXTURE multiple-phase model was set to simulate the initial ignition. The water vaporization was researched and the energy transfer was added to the energy equations. The flow field and the vaporization were calculated coupled. The initial ignition process of the underwater solid rocket motor is obtained and the vaporization influence to the underwater launching is analyzed. The "neck", "inverted jet" and "eruption" phenomenon of the bubble are observed. The bubble increases more rapidly because the steam mass added to the fuel. The temperature is lower considering the vaporization because the steam enthalpy is lower than the fuel enthalpy and the flow field of the initial ignition of the underwater-launching solid rocket motor is accordant well to the reference.

Adaptive SINS/GPS Outlier Detection and Accommodation Using Innovation Orthogonal

ZUO Kai, ZHONG Mai-ying, LIU Bai-qi, GONG Xiao-lin

2010, 19(4): 427-431.

[Abstract](644) [PDF 294KB](315)

Abstract:
The outlier detection and accommodation of integration navigation of strapdown inertial navigation systems and global position system (SINS/GPS) were studied. Based on analyzing the innovation orthogonal property in Kalman filter, an outlier adaptive detection approach was first presented, which included the determination of evaluation function and threshold and the logic decision of outlier occurrence. To effectively attenuate the influence on estimation accuracy, a modified Kalman filter algorithm was proposed by accommodation of the dynamic data with outlier. Results of data processing from vehicle-test SINS/GPS integration navigation show the effectiveness of the proposed method.

Experimental Study of an Active Body-Weight Support System for Low Limbs Rehabilitation Training

QIAO Bing, LIANG Jian-xun, MA Ou

2010, 19(4): 432-438.

[Abstract](539) [PDF 463KB](200)

Abstract:
An experimental study of an active body-weight support (BWS) system for improving treadmill-based locomotion training is performed. The dynamical foundation of the proposed system is developed based on a simplified cable suspended mass-spring-damping system which is used to mimic the vertical gait of a walking human. A specifically designed cable pulley suspended cam-slider system is used to mimic the walking gait of a human in vertical direction. A load cell is installed to connect the slider and the cable which is driven by a winch based on the acceleration feedback. The contact force between the slider and the cam is measured to evaluate the walking load of the system. The experimental results demonstrate that the proposed active BWS system can simultaneously reduce both gravitational and inertial load of the walking body, which implies that the walking body suspended in such a BWS system will dynamically behave as if certain amount of body mass had been removed.

Error Model of Rotary Ring Laser Gyro Inertial Navigation System

ZHANG Lun-dong, LIAN Jun-xiang, WU Mei-ping, ZHENG Zhi-qiang

2010, 19(4): 439-444.

[Abstract](3250) [PDF 343KB](814)

Abstract:
To improve the precision of inertial navigation system (INS) during long time operation, the rotation modulated technique (RMT) was employed to modulate the errorr of the inertial sensors into periodically varied signals, and, as a result, to suppress the divergence of INS errors. The principle of the RMT was introduced and the error propagating functions were derived from the rotary navigation equation. Effects of the measurement error for the rotation angle of the platform on the system precision were analyzed. The simulation and experimental results show that the precision of INS was ① dramatically improved with the use of the RMT, and ② hardly reduced when the measurement error for the rotation angle was in arc-second level. The study results offer a theoretical basis for engineering design of rotary INS.

Efficient Stereo Matching Scheme Based on Graph Cuts

HOU Guang-qi, WEI Ping, Wang Shu-hua

2010, 19(4): 445-449.

[Abstract](673) [PDF 774KB](237)

Abstract:
A new stereo matching scheme from image pairs based on graph cuts is given, which can solve the problem of large color differences as the result of fusing matching results of graph cuts from different color spaces. This scheme builds normalized histogram and reference histogram from matching results, and uses clustering algorithm to process the two histograms. Region histogram statistical method is adopted to retrieve depth data to achieve final matching results. Regular stereo matching library is used to verify this scheme, and experiments reported in this paper support availability of this method for automatic image processing. This scheme renounces the step of manual selection for adaptive color space and can obtain stable matching results. The whole procedure can be executed automatically and improve the integration level of image analysis process.

Research of Point Diffraction Interferometer for the Measurement of Laser Beam

WANG Gang, YAN Ji-xiang

2010, 19(4): 450-454.

[Abstract](617) [PDF 326KB](252)

Abstract:
Laser beam measurement using point diffraction interferometer (PDI) is studied by modeling and the factors that influence the measurement accuracy are investigated. First, zernike polynomial is used to fit aberrated wavefront and the behavior of pinholes diffraction with different aberrated wavefront is analysed. The following essential work on the PDI sensor is to get balance between intensity of the spherical reference wave and test wave. Then the optimum parameters for the model are obtained: wavelength of laser is 1 024 nm; pinholes diameter is 2 μm; size of the focus spot is 20 μm; if gold (Au) is chosen as layer on film, its thickness should be 0.05 μm. The optimization results are only suited to the current PDI system, but the method presented is applicable to other configurations of high-accuracy PDI design.

Application of Modified SPECAN Algorithm in Parasitical BiSAR

TIAN Wei-ming, GAO Li-ning, LONG Teng, HU Cheng

2010, 19(4): 455-459.

[Abstract](566) [PDF 583KB](261)

Abstract:
Global navigation satellite system (GNSS) can be employed as a transmitter to composite bistatic synthetic aperture radar (BiSAR). As GNSS signal is quite different from the traditional radar signal, modified spectral analysis (SPECAN) algorithm is proposed and applied in the BiSAR system. The modifications include Doppler centroid compensation, range curve correction and azimuth processing method. The modified SPECAN algorithm solves the imaging problem under the condition of huge range migration, long synthetic aperture time and phase-coded signal. The proposed algorithm is verified by experiment results.

Analysis of Moving Target Detection in Space-Surface BiSAR

HU Cheng, TIAN Wei-ming, ZENG Tao, ZHOU Chao

2010, 19(4): 460-465.

[Abstract](558) [PDF 343KB](241)

Abstract:
Based on the geometric structure of multi-channel space-surface bistatic aperture radar (SS-BiSAR), the time-frequency and spatial-frequency relationships of clutter and moving target are detailedly analyzed. It is found that the prepositive stationary receiver can improve the spatial separation between moving target and correspondingly competitive clutter, furthermore the processing scheme of space-time adaptive processing (STAP) in SS-BiSAR echo domain is given. Meanwhile, compared to the STAP in monostatic synthetic aperture radar (SAR), it is firstly proved that the minimum detectable velocity in SS-BiSAR system can improveR₀/R₁(transmitter-to-target distance over receiver-to-target) times. Finally, the computer simulation verifies the effectiveness of the STAP processing scheme.

Nonisothermal Kinetics of Free-Radical Polymerization of 2,2-Dinitropropyl Methacrylate

HUANG Yong-feng, ZHANG Gong-zheng, XU Qin

2010, 19(4): 466-470.

[Abstract](649) [PDF 299KB](286)

Abstract:
The 2,2-dinitropropyl methacrylate (DNPMA) was synthesized by esterification ofα-methacrylic acid with 2,2-dinitropropanol. The free-radical bulk polymerization of DNPMA in the presence of 2,2-azobisisobutyronitrile (AIBN) was investigated by differential scanning calorimetry (DSC) in the nonisothermal mode. Kissinger, Ozawa and Barrett methods were applied to determine the activation energy (E_a) and the reaction order of the free-radical polymerization. The results showed that the temperature of exothermic polymerization peaks increased with increasing heating rate. With increasing the molar ratio of monomer/initiator and the heating rate, the reaction order of nonisothermal polymerization was approximately equal to 1. The averageE_avalue from Kissinger and Ozawa methods (77.74±1.07 kJ/mol) was smaller than the value from the Barrett method (E_a102.36 kJ/mol).

Mechanical Properties of Phenolic-Resin Composites Reinforced with CF/BF Interlayer Hybrid Fibers

LI Wei-dong, CAO Hai-lin, CHEN Guo-rong, SHI Peng-fei

2010, 19(4): 471-475.

[Abstract](653) [PDF 369KB](288)

Abstract:
Phenolic-resin composites reinforced with carbon fiber (CF) and basalt fiber (BF) interlayer hybrid fibers plain fabric were fabricated. The tensile strength, compressive strength and interlaminar shear strength of the prepared composites were studied. The results indicated that hybrid fibers reinforced composites possessed the advantages of both CF and BF. When resin content was 35% by volume fraction, the comprehensive mechanical performance of BF/CF reinforced phenolic resin composites reached the optimal values with the warp and weft direction tensile strength, compressive strength and interlayer shear strength being 252 MPa and 487 MPa, 105 MPa and 129 MPa, 21 MPa and 20 MPa, respectively. The scanning electron microscope (SEM) observations showed that the BF/CF hybrid fibers reinforced composites had better interfacial adhesion.

Studies of the Oxidation of Hexabenzylhexaazaisowurtzitane

LI Ya-yu, WANG Lin, LIN Qiu-han, MA Qiao-li, PANG Si-ping, YU Yong-zhong

2010, 19(4): 476-479.

[Abstract](742) [PDF 263KB](339)

Abstract:
A series of oxidation reactions of hexabenzylhexaazaisowurtzitane (HBIW, 1 ) were studied. Compound 1 was treated with potassium permanganate in CH₂Cl₂by adding Na₂CO₃to adjust pH to 7-8 to obtain tetrabenzoyldibenzylhexaazaisowurtzitane ( 3 ) with a yield of 70%. With acetic anhydride (Ac₂O) as solvent, monoacetyltribenzoyldibenzylhexaazaisowurtzitane ( 4 ), diacetyldibenzoyldibenzylhexaazaisowurtzitane ( 5 ), triacetylmonobenzoyldibenzylhexaazaisowurtzitane ( 6 ) and tetraacetyldibenzylhexaazaisowurtzitane ( 7 ) were also obtained from the oxidation of compound 1 . The results show that only the oxidative cleavage of the cage system in compound 1 was observed in most cases. The cleavage was a cation catalysis mechanism.

Study of Flame Retardation of Polycarbonate Modified by Polyhedral Oligomeric Silsesquioxane and Caged Bicyclic Phosphate

JIANG Yun-yun, YANG Rong-jie

2010, 19(4): 480-486.

[Abstract](531) [PDF 383KB](274)

Abstract:
The flame-retarded polycarbonate (PC) has been made with octaphenyl polyhedral silsesquioxane (OPS) and/or caged bicyclic phosphate (Trimer). Thermal gravimetric analysis (TGA), Fourier-transform infrared (FTIR), TGA-FTIR, limiting oxygen index (LOI), and mechanical tests have been employed to characterize the modified PC. The additives of OPS and Trimer in PC have been proved to be effective flame-retardants because of the synergistic interaction between the elements of P and Si. The role of OPS and Trimer in PC degradation are different: OPS participates in the charring of PC, while Trimer makes PC degrade in advance. In addition, OPS and Trimer induced obvious differences in the mechanical properties of PC.

Manifolds with Special Commuting Jacobi Operators

ZHANG Feng-yun, ZHAO Yan, SUN Hua-fei

2010, 19(4): 487-490.

[Abstract](579) [PDF 241KB](261)

Abstract:
For a Riemannian manifold(Mⁿ,g)with curvature tensorR, the Jacobi operatorJ(X)is give. In this paper, the flat Riemannian manifolds are characterized in terms of special commutation properties of their Jacobi operators.

Information Geometric Structures for the Thermodynamic Manifold

ZHANG Shi-cheng, SUN Hua-fei, LI Chun-hui

2010, 19(4): 491-494.

[Abstract](547) [PDF 263KB](269)

Abstract:
In view of information geometry, the state spaceSof thermodynamic parameters is investigated. First a Riemannian metric forSis defined and then theα-geometric structures ofSis given. Some of results obtained by other authors are extended.

Positive Pseudo-Symmetric Solutions for Some Nonlinear Systems at Resonance

ZHANG Li, GE Wei-gao

2010, 19(4): 495-498.

[Abstract](720) [PDF 257KB](235)

Abstract:
By means of an extension of Mawhin’s continuation theorem due to Ge, this work shows the existence of at least one positive pseudo-symmetric solution of the multi-point boundary value system.The interesting fact is that the nonlinear terms are involved in the first order derivatives.

2010 Vol. 19, No. 4