bob手机在线登陆学报自然版

2017, 37(4): .

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2017, 37(4): .

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Dynamic Behavior of Non-Deformable Projectiles with Different Nose Shape Penetrating Steel Plate

YU Qing-bo, GUO Huan-guo, ZHANG Tian-yuzi, XIAO Yan-wen, WANG Hai-fu

2017, 37(4): 331-336. doi:10.15918/j.tbit1001-0645.2017.04.001

Abstract(1283) PDF(1459)

Abstract:
Dynamic behavior of non-deformable projectiles with different nose shapes penetrating steel plate was simulated by Autodyn-3D finite element code. The numerical simulation results show that projectile's nose shape significantly affects the penetration behavior and failure mode of steel plate. When penetrating the steel plate by a blunt nose shape projectile, the typical dynamic behavior appears an adiabatic shear band formation and propagation initially, then inducing a plug ejection finally, with a thickening plug while increasing the impact velocity. For a hemispherical projectile penetrating, the steel plate shows a typical dynamic behavior of necking close and enlarging hole, and the size of the plug induced by necking close decrease with the impact velocity decrease. As penetrated the steel plate by a conical projectile, a typical dynamic behavior of permanent radial compressive and enlarging hole is produced, then resulting in a petal perforation finally.

Quasi-Static Compression Properties of Cold Isostatically Pressed Reactive Materials

XIAO Yan-wen, XU Feng-yue, ZHENG Yuan-feng, YU Qing-bo, WANG Hai-fu

2017, 37(4): 337-341,347. doi:10.15918/j.tbit1001-0645.2017.04.002

Abstract(1342) PDF(1114)

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Quasi-static compression experiments were performed on cylindrical specimens of cold isostatically pressed PTFE/Al/W reactive materials to study its mechanical response behavior and properties. The influences of density on Young modulus values of reactive materials were obtained by analyzing the quasi-static stress-strain curve at elastic deformation stage. The experimental results show that the ultimate compression strength and Young modulus of cold pressed PTFE/Al/W reactive materials present an increasing trend with the increase of reactive material density, and the cracks produced by quasi-static loads form in a range of angles from 30° to 45°. In addition, based on typical scanning electron microscope images of the uncompressed and compressed specimens with different density, it is showed that the number of force chains increases with an increasing reactive materials density, resulting in the increase of ultimate compression strength and Young modulus of reactive materials.

Experimental Study on the Evolution of the Temporary Cavity in a Typical Small Caliber Rifle Bullet Penetrating Gelatin

HUANG Shan, XU Cheng, WEN Yao-ke, DOU Xun

2017, 37(4): 342-347. doi:10.15918/j.tbit1001-0645.2017.04.003

Abstract(1532) PDF(1128)

Abstract:
In order to understand the formation and development law of the cavity with the small caliber rifle bullet penetrating the gelatin, an experiment was carried out, taking 4℃/10% concentration ratio, size of 300mm×300mm×300mm gelatin as target, and the high speed photography for measurement. Three 5.56mm SS109 bullet's high speed photography and pressure curves of penetrating gelatin at 100 meters range were presented. Through processing the data and comparatively analyzing with the data of 7.62mm rifle bullet, results show the following conclusions:the max diameter of temporary cavity is within 200~270mm, the pulse cycle is about 11μs; the diameter of temporary cavity is attenuating as half sine wave curve with the penetration time; the shape and size of the killing element influence remarkably on the shape of the temporary cavity, thereby can relate to the lethal power of the ammunition.

Analysis on the Gas Interference Characteristics During the Transonic Gasbag Separation of Cluster Munition

WANG Jin-long, WANG Hao, JIANG Kun, TAO Ru-yi

2017, 37(4): 348-353,359. doi:10.15918/j.tbit1001-0645.2017.04.004

Abstract(1146) PDF(1220)

Abstract:
To analyze the gas interaction influence on the dynamic characteristics of the sub-munitions during the transonic separation of the cluster munitions, a three-dimensional dynamic model was built and the process of separation under the action of gas interference was simulated based on the experiment tests at the three-typical separation Mach numbers:0.8Ma, 1.2Ma, 3.0Ma. The dynamic characteristics of the sub-munitions caused by the gas interference were analyzed. And a boundary grid adaptive method was used to improve the separation feature. The results show that the gas interference mainly exists in the initial separation phase. With the increase of the separation Mach number, the effect of the gas interference becomes weaker under the influence of the flow field and shock wave. The existence of the gas interference has a certain influence for the angular velocity. The initial disturbance time is 12, 10, 5ms which makes the angular velocity value increased by 54%、97%、3% respectively.

Simulation Calculation of Combustion Chamber for Button Turbojet Engine

MA Hong-peng, FANG Shu-zhou, GAO Hang, LI Teng, FANG Guan-lin

2017, 37(4): 354-359. doi:10.15918/j.tbit1001-0645.2017.04.005

Abstract(1752) PDF(1920)

Abstract:
To provide reference data for ultra-micro combustor, a new type button turbojet engine was designed and simulated in the combustion's steady-state process. The boundary condition of inlet was calculated with isentropic numerical calculation taking into account turbulent chemical reaction, heat radiation, and so on, to get the combustion chamber's steady-state of the velocity, temperature and component concentration distribution, to analyze the fuel/air flow and backflow, combustion efficiency and total pressure recovery coefficient, and to compare with the experimental data. The calculation results can accurately reflect the actual combustion. The results show that, when combustion chamber exit velocity is about 65m/s, outlet temperature is around 1000K, the simulation and experimental data are more similar, combustion chamber structure design is reasonable.

Multilevel Coding Technology Based on Kite Code in AWGN Channel

JIA Dai, SHANGGUAN Cheng-lin, FEI Ze-song, CAO Cong-zhe, WANG Jing

2017, 37(4): 360-364. doi:10.15918/j.tbit1001-0645.2017.04.006

Abstract(1199) PDF(1503)

Abstract:
Multilevel coding (MLC) scheme, combining coding and modulation technology, does not take up additional bandwidth resources and does not reduce the effective data transmission rate as well, but it can truly improve the reliability of data transmission. According to the multilevel coding feature of the MLC technology and the channel coding theory, it is evident theoretically that the combination of the rate-less code and the MLC technology would get better performance of bit error rate and throughput. As a new type of rate-less code, Kite code has the advantages of both fountain code and LDPC code. In this paper, a new MLC method was designed based on the calculation of the channel capacity of each equivalent channel, taking Kite code as the component code, combining BP set segmentation and high order modulation mode. Simulation results show that the decoding performance of the MLC technology with Kite code as component code is far better than that of the MLC technology with traditional fountain code as component code.

CSI Feedback Based on Multi-Paths Information in Dual-Polarized MIMO System

ZHENG Feng, CHEN Yi-jian

2017, 37(4): 365-370. doi:10.15918/j.tbit1001-0645.2017.04.007

Abstract(1173) PDF(1320)

Abstract:
The space limitation of antenna disposition and CSI precision are the important factors that influence the performance of massive MIMO. Dual-polarized antenna can be widely adopted to accommodate a large number of antenna elements in limited space. However, CSI feedback schemes in LTE are not efficient for FDD based massive MIMO as feedback overhead increases almost linearly with the increase of antenna number. Moreover, the codebook will also be huge and difficult to design if reusing the LTE methodology. In this paper, a novel CSI feedback mechanism was proposed for dual-polarized antenna system to achieve better performance with low feedback overhead. The MIMO channel was decomposed into long term components (multi-path directions and amplitudes) and short term component (multi-path phases). The relationship between the two components and the optimal pre-code was also deduced in closed form. System level simulation results show that it can improve the performance considerably, improving feedback efficiency quantitatively and reducing the complexity of terminal.

8031 Microcontroller Software Vulnerability Detection Algorithm Based on Vulnerability Knowledge Database

SHAN Chun, JING Gao-peng, HU Chang-zhen, XUE Jing-feng, HE Jin-zhao

2017, 37(4): 371-375. doi:10.15918/j.tbit1001-0645.2017.04.008

Abstract(1325) PDF(1298)

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The 8031 microcontroller software are currently used widely and its security issue become increasingly prominent. In view of this, the authoritative vulnerability databases were studied, extracted knowledge from attacks through a rule of ECV, classified security vulnerabilities according to the type and characteristics based code security, designed three-tier structure vulnerability knowledge database, and proposed a knowledge-based vulnerability detection algorithm based on the vulnerability knowledge library to detect the vulnerability of 8031 microcontroller. Designed and implemented a software security reverse-analysis system for 8031 binary program, and the effectiveness and availability of the vulnerability knowledge database and the rule of ECV were verified. The experimental result shows that the algorithm can correctly detect the target program vulnerability, having great significant in reducing the number of software vulnerabilities and saving lots of cost in detecting software vulnerability.

Image Denoising Method Based on Wavelet Transform and Bilateral Filter in Vehicle Gesture Recognition

QIANG Yan, ZHANG Xiao-hui

2017, 37(4): 376-380. doi:10.15918/j.tbit1001-0645.2017.04.009

Abstract(1138) PDF(1260)

Abstract:
Gesture interaction is the important research area in human-computer interaction. Vehicle gesture recognition system can reduce the distraction caused by operating instrument and improve the safety of driving. Influenced by illumination changes, the internal environment of the car, camera imaging quality and other factors, large amount of complex noise exists in the vehicle gesture images, which seriously affect the accuracy of gesture segmentation, feature extraction and gesture recognition. In this paper, an image processing method suitable for vehicle gesture images was proposed to solve this problem. In this method, one-dimensional nonlinear diffusion filtering was used to remove the noise in the high frequency sub band after wavelet decomposition and get the preliminary denoising image. Then, the preliminary denoising image was further denoised by multi-scale bilateral filtering. Experiment results show that the proposed method can better remove the noise and prevent the blurring of details of the vehicle gesture image than other methods.

Research on Ad Hoc Network Optimization Based on Chaotic Particle Swarm Optimization

CHAI Bao-ren, GU Wen-cheng, HAN Jin-ku

2017, 37(4): 381-385. doi:10.15918/j.tbit1001-0645.2017.04.010

Abstract(1250) PDF(1017)

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Chaotic particle swarm optimization (C-PSO) was proposed based on chaos theory to optimize the optimization index of Ad Hoc network. In the process of network optimization, C-PSO algorithm took full advantage of chaotic system in the randomness, ergodicity and sensitivity to avoid the “precocious” phenomenon of PSO algorithm, to avoid falling into the local optimal area, and to enhance the global collection capacity. Based on the NS-3 simulation system, the simulation results of C-PSO algorithm and PSO algorithm were tested.Through comparing and analyzing the three network performance indexes of packet loss rate, network life cycle and network throughput, the results show that C-PSO algorithm is superior to PSO algorithm, which verifies the validity and reliability of C-PSO algorithm for Ad Hoc network optimization. The algorithm can be applied to realize optimization of Ad Hoc network.

Speech Emotion Recognition Based on Decision Tree and Improved SVM Mixed Model

ZHAO Juan-juan, MA Rui-liang, ZHANG Xiao-long

2017, 37(4): 386-390,395. doi:10.15918/j.tbit1001-0645.2017.04.011

Abstract(1451) PDF(2199)

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To effectively improve the accuracy of speech emotion recognition in intelligent man-machine harmonious interaction, a method of speech emotion recognition was proposed based on decision tree and an improved SVM mixed model. This method can avoid the tree unbounded generalization error, more the number of classifiers and other shortcomings, while taking advantage of SVM-KNN mixed model to avoid constrained optimization problems and improve the recognition efficiency. In this paper, six basic emotions were identified, including sadness, joy, anger, disgust, surprise, fear. Experimental results show that this method can effectively identify six basic emotions. Compared with the traditional support vector machine and artificial neural network method, this method can get higher recognition accuracy, better stability, strong practicability and generalization ability.

A Watermarking Scheme Based on Normalization and Nonsubsampled Contourlet Transform

ZHU Dan-dan, LÜ Li-zhi

2017, 37(4): 391-395. doi:10.15918/j.tbit1001-0645.2017.04.012

Abstract(1042) PDF(1049)

Abstract:
A new watermarking algorithm scheme was presented based on normalization and nonsubsampled Contourlet transform knowledge, extracting low frequency sub-band of the image with nonsubsampled Contourlet transform, and then embedding the low frequency sub-band in a significant region for normalization according to the human visual system (HVS) and the correlation between the coefficients of the embedded watermark before and after. Without the aid of the original image, the watermark can be extracted and the real blind detection can be realized. The experimental results show that, the proposed watermarking algorithm has the best resistance to shift transform, and has the better resistance to rotation and zoom. After JPEG compression, the digital watermark is not distorted.

Radio Resource Allocation for Cellular and Device-to-Device Communication Hybrid Networks

TONG Zhao, LI Bing-bing, HUI Yong-tao

2017, 37(4): 396-400,429. doi:10.15918/j.tbit1001-0645.2017.04.013

Abstract(1111) PDF(2103)

Abstract:
For the solution of resource allocation in the cellular and D2D communication hybrid networks could be formulated into an optimization problem with the objective of maximizing network throughput, a two-step resource allocation scheme was further designed based on this model. First, the resource blocks were assigned to the users with an improved greedy spectrum allocation algorithm. And then, the dual-decomposition based algorithm was employed to allocate optimal transmission power for each resource block. Moreover, based on consideration of QoS requirement for cellular users, the proposed algorithm no longer restricted the number of D2D users on each resource block and resources reused by D2D user. The simulation results show that, the proposed algorithm makes an effective improvement in capacity of whole system while still retains the rate of cellular users.

Modelling and Analysis on the Characteristics of Dual-Chamber Hydro-Pneumatic Suspension

SANG Zhi-guo, DONG Ming-ming, QIN Ye-chen, Gu Liang

2017, 37(4): 401-405. doi:10.15918/j.tbit1001-0645.2017.04.014

Abstract(1256) PDF(1385)

Abstract:
Ride comfort and road-holding are effected by the vehicle suspensions.The dual-chamber hydro-pneumatic (DCHP) suspension is a novel passive suspension system. This paper discribes the operating principle of the DCHP suspension and establishes its parametric model. Through the transfer functions comparisons between the traditional passive suspension and the DCHP suspension, it's found that the equivalent stiffness and damping coefficient can adjust their own values according to the frequency of the excitation from road surface. The multi-objective optimization of suspension parameters is implemented with NSGA-Ⅱ algorithm. The results indicate that all three performance metrics of the novel system are better than those of the traditional passive suspension. The above conclusion is verified by the simulation in time domain with suspension parameters provided by the Pareto solutions.

Dimensionality Reduction of State-Space Model Based on Projection Theory and Orthogonalization

ZHANG Ke-yu, HAN Yong-ming

2017, 37(4): 406-411. doi:10.15918/j.tbit1001-0645.2017.04.015

Abstract(1238) PDF(1121)

Abstract:
A new setting method was proposed for state space system, being able to estimate state space directly without increasing the dimension of state variables when a lagged state variable existed in measurement equation. The improved state-space system can be estimated still by the regular Kalman filter and have a strongly improvement in point estimate. Moreover, the Durbin and Koopman(D-K) sampling methodology can be utilized to smooth the state variable for Kalman smoother. A simulation experiment of the improved state-space system and comparison with the traditional method were conducted. The results show that, when in point estimation, the value of two systems is almost the same, but the improved model can reduce the computational time. Furthermore, D-K method seems more efficient comparing with the Kalman smoother, validating the efficiency of the posed method.

Multi-Phase Trajectory Optimization of Vehicle Based on hp-Adaptive Pseudospectral Method

QIU Wen-jie, MENG Xiu-yun

2017, 37(4): 412-417. doi:10.15918/j.tbit1001-0645.2017.04.016

Abstract(1459) PDF(1782)

Abstract:
In order to solve the trajectory optimization problem of a boost-glide vehicle with multi-phase and multi-constraint, a longitudinal motion model and a multi-phase trajectory optimization model were built based on the constraint consideration of velocity, switch point of trajectory phase and the parameter of trajectory end. Hp-adaptive-based Legendre-Gauss-Radau points were used to transcribe the optimization problem to a finite-dimensional nonlinear programming problem, and maximal downrange optimization trajectory was obtained. An improved optimization strategy was proposed based on dynamic programming theory to decide the switch points of free phases, due to the difficulty with the multi-phase trajectory optimization arithmetic. Compared with the hp-adaptive pseudospectral method, the improved strategy can get almost the same optimization trajectory and a smaller finite-dimensional approximation. Numerical simulation results show that the boost-glide vehicle trajectory optimization problem can be solved, and the results are better than the gliding trajectory with the maximum lift-to-drag ratio.

Pursuit Evasion Game with J2 Perturbation

WANG Qiang, YE Dong, FAN Ning-jun, WU Yan-xuan

2017, 37(4): 418-423. doi:10.15918/j.tbit1001-0645.2017.04.017

Abstract(1642) PDF(2266)

Abstract:
A two-side optimization problem where the intercepting satellite pursued the target satellite was studied in this paper. In the pursuit-evasion game, it was assumed that both sides use the continuous thruster and suffer from the earth central gravity with J2 perturbation. The dynamics equations were established to describe their three dimensional motion. Then the optimal control outputs of both side satellites were obtained by building the systems Hamilton and applying the functional extremal condition. The pursuit evasion games was transformed to the two point boundary value problem. At last the new problem was solved with the mixed numerical method where an initial solution was acquired by the genetic algorithm and sent to nonlinear programming as its starting value. Simulation was used to obtain the optimal interception and escaping trajectories of the two satellites and validate the proposed method.

Soot Characteristic and Formation Mechanism in the Process of Gas Explosion

NIE Bai-sheng, YANG Long-long, WANG Cheng, HUANG Jin-xin

2017, 37(4): 424-429. doi:10.15918/j.tbit1001-0645.2017.04.018

Abstract(1302) PDF(1214)

Abstract:
The phenomenon emerging some bright spots in observation window during gas explosion was analyzed. Results show that it is the soot particles with high thermal radiation property that yield this intense light. The characteristics of soot aperture and surface structure were investigated based on low-pressure nitrogen gas adsorption (LP-N₂GA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. The results show that soot particles possess a specific surface area of 1.507m²·g^-1(DFT) and pore volume of 4×10^-3cm³·g^-1. The images of SEM illustrate that the soot particle is composed of abundant spherical aggregations with a diameter range from 4μm to 50μm. The pores at the particle surface are well developed, some of the particles exhibits an ablation feature. The soot aggregates are botryoidal and some of primary particles bond together, the diameter of majority particles are of 100nm from TEM images. The graphite layer with lattice fringes can be seen from the primary particles. The infrared spectroscopy analysis shows that soot particles contain a large amount of polycyclic aromatic hydrocarbon, aromatic series and other functional groups.

Damage Assessment Method of Components Based on Finite Element Interaction

LI Xiang-rong, LI Shuai, WANG Guo-hui, LI Guo-dong, LI Fan

2017, 37(4): 430-435. doi:10.15918/j.tbit1001-0645.2017.04.019

Abstract(1059) PDF(1289)

Abstract:
Battle damage assessment of weapon equipment component level is the foundation to realize exact equipment support simulation during the war, as well as the basis to forecast wartime exact service. Taking the high explosive shell against main-battle tank as example, an interaction model was built for target and warhead based on finite element analysis. Based on a component damage criteria described with probability form, the main-battle tank barrel's critical damage thickness was analyzed. Results show that the critical penetration depth of gun barrel muzzle and turret is 35mm and 85mm respectively. A finite element interaction program was developed for the main-battle tank and grenade fragments, and carried out an example calculation. Research results can be applied to damage assessment of grenade fragment against other weapon equipment components, which provides support for the battle repair and accurate maintenance support.

The Information Geometric Structures of the Sizes of Grains

ZHANG Zhen-ning, SUN Hua-fei, HAN Xi-wu, CAO Li-mei

2017, 37(4): 436-440. doi:10.15918/j.tbit1001-0645.2017.04.020

Abstract(977) PDF(1190)

Abstract:
The parameter space of sizes of normal grown grain was investigated from the viewpoint of information geometry. As the diameters of grains could be described with lognormal distributions, the geometric structures of the manifold with lognormal distributions were considered to analyze the diameters of grains. The obtained manifold is a hyperbolic space with a negative constant curvature. Meanwhile, the geodesic equations were obtained and solved. And then the relations between the Kullback divergence and the arc length were analyzed. At last, the divergence of the Jacobi fields was considered.

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