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2017, 37(8): .

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2017, 37(8): .

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Experimental Investigation of Submerged Bubble Evolution on Annular and Circular Nozzles

HU Jun, LI Ting-ting, YU Yong, JIANG Jian-yu

2017, 37(8): 771-777. doi:10.15918/j.tbit1001-0645.2017.08.001

Abstract(1068) PDF(1413)

Abstract:
An experimental study on bubble formation of annular and circular nozzles was carried out. The bubble formation was recorded by a high-speed camera and detailed characteristics of bubble formation were obtained. Based on the analysis of the experimental images, the similarities and differences of bubble formation in the two kinds of nozzles were explored. The results show that the bubble formation of the circular nozzle presents the law of bubbling regime, which can be divided into three periods:period-1, period-2 and period-3, while the annular nozzle exhibits only period-3 bubbling regime features when the gas can be ejected stably from the entire annular section. In period-3 bubbling regime, when the subsequent bubble detaches from the two nozzles, the maximum heights of the whole bubble are different. The various forces acting on the bubbles are changing, and the three types of bubble are controlled by different main control forces.

Modeling of the Gas Leakage of Premade Fragment Warhead

LI Yuan, LI Yan-hua, LIU Chen, WEN Yu-quan

2017, 37(8): 778-782. doi:10.15918/j.tbit1001-0645.2017.08.002

Abstract(1025) PDF(1080)

Abstract:
Premade fragment warhead has the advantage of almost 100 percent control of the fragment mass and shape, but the acceleration velocity of the fragment will be affected by the early leakage of detonation product. In order to analyze the influence of gas leakage on the fragment lethality, numerical modeling was used to study the leakage process of certain premade fragment warhead and computing results from different algorithms were compared with the experiment. The results show that when initiated at one end center, the gas leakage mainly happens circumferentially, having a huge influence on the fragment dispersions. The fragment velocities and ejection angles results of fluid-solid couple algorithm agree best with the experiment results, with the least relative errors of 1.12% and 0.56% respectively. Given the robustness, precision, and time of calculation, the fluid-solid algorithm is a reliable tool for studying the gas leakage of warhead.

Effecting Factors on the Heat-Transfer Characteristics of the High Temperature and High Speed Jet Impinging to a Plate

WANG Xiao-guang, SONG Qiu-zhi, REN Ming

2017, 37(8): 783-788. doi:10.15918/j.tbit1001-0645.2017.08.003

Abstract(957) PDF(1170)

Abstract:
To study the heat-transfer characteristics of high temperature and high speed jet impinging a plate, simulations and experimental research were conducted to verify the validity of the SST-SAS model. On this basis, the effectsof factors likeinlet boundary (turbulence intensity I, gun exitD, velocity to temperature ratio), jet-to-plate spacingH/D, plate inclination angleθ, plate temperatureT_won the Nusselt number and high temperature jet impinged area were studied. Then, the average Nusselt number of the high temperature jet impinged region was statistically analyzed. The results show that I,u₀/T₀,H/Dandθhave a great effect on the Nusselt number and high temperature jet impinged area; but the impact ofDandT_wwas limited. In addition, the change of average Nusselt number of the high temperature jet impinged area is contrary to that of the high temperature jet impinged area,and its numerical value is one magnitude greater than the low temperature and low velocity jet impingement, and the value range is 1 321 to 3 873.

Penetration and Blast Combined Damage Effects of Reactive Material Jet Against Steel Target

ZHANG Xue-peng, XIAO Jian-guang, YU Qing-bo, ZHENG Yuan-feng, WANG Hai-fu

2017, 37(8): 789-793,800. doi:10.15918/j.tbit1001-0645.2017.08.004

Abstract(1332) PDF(1083)

Abstract:
The damage effects of reactive material jet against steel targets were researched by the combination of static explosive experiments and theoretical analysis. The experimental results show that, compared with the traditional metal jet, the diameter of the penetration hole formed by reactive material jet in steel targets was much larger together with stronger blast-induced crack effects, while the penetration depth shows a significant decrease. Based on the quasi-steady incompressible fluid theory and modified Bernoulli equation, a theoretical model for analyzing the penetration and blast combined damage effects was developed to consider the self-delay imitation time of reactive material jet. As such, a theoretical explanation from the perspective of damage mechanism about the combined damage effects was presented by this analytical model.

Numerical Simulation of Damage Behavior for Submunition Payloads Subjected to Kinetic Kill Vehicle

WANG Yong-zhi, GONG Jie, JIN Xue-ke, WANG Hai-fu

2017, 37(8): 794-800. doi:10.15918/j.tbit1001-0645.2017.08.005

Abstract(965) PDF(846)

Abstract:
To investigate the lethality of kinetic vehicle against chemical submunition tactical ballistic missile, numerical simulations were carried out with Autodyn Hydrocode. The influences of strike angle and impact point on the damage effect of submunition were analyzed. The results show that, the damage effect of simulated submunition payload was significantly influenced by the impact point and strike angle. The damage rate of submunition was improved obviously when the impact point at the geometric center or the interface of submunition tiers. The optimal range of strike angle is different for various impact points. The damage effect is better for the situation of small strike angle and the impact point at the front of submunition payload, for another situation is upright strike angle and the impact point at the middle part or tail end. All these works can be beneficial to lethality assessment, interception mode adoption and KV optimum design for negating ballistic missile in midcourse phase.

Study on Parameters Determination of Marble RHT Model

LI Hong-chao, LIU Dian-Shu, ZHAO Lei, LI Chen, ZHANG Zhen-yuan

2017, 37(8): 801-806. doi:10.15918/j.tbit1001-0645.2017.08.006

Abstract(944) PDF(861)

Abstract:
RHT model includes 34 parameters. The values ofA,n,f_s^*,f_t^*,Q₀,g_c^*,ξ,D₁,ε_p^m,A_f,n_f,p_compandNare hard to be determined due to the complicated experimental methods.In previous researches on simulation of rock blasting based on RHT model, many scholars quoted directly from the relevant parameters of concrete or they simply modified values of concrete parameters with little consideration of the kinds of rock material.To get the fairly accurate relevant parameter values of marble, the orthogonal experiment method and LS-Dyna numerical computation were used in this paper to determine and optimize the above parameters on the basis of static tests, wave velocity tests and SHPB impacting experiments. This paper also made a comparison between the simulation curves before and after the optimizing and the stress-strain curves of marble specimen processed by the SHPB impacting experiment.The final results show that the errors between the simulate curve and SHPB impacting experiment curve were decreased dramatically after the parameters had been processed by the orthogonal experiment.The appropriate parameters of the marble RHT model were obtained.

Theoretical Study and SHPB Experimental Verification on the Critical Damage of Uniform Sandstone

LI Sheng-lin, ZHANG Qing-cheng, WU Shuai-feng, LIU Zhen-shuai

2017, 37(8): 807-812,823. doi:10.15918/j.tbit1001-0645.2017.08.007

Abstract(887) PDF(1118)

Abstract:
Under the impact load, sandstone usually fails when the damage quantityDis less than 1, and there exists the critical damage. Based on the fractal geometry theory and the structure features of sandstone, a 2×3 cellular model was established in this paper. The instability critical damage of sandstone is 0.4 after theoretical calculation, and the critical damage of stage change is 0.119. Results analysis of theΦ50 mm SHPB experiment shows that there are two critical points in the dynamic damage process of sandstone:the first critical point is from the linear damage stage to the accelerated damage stage, and the corresponded damage quantity is about 0.1; the second critical point is from the damage stage to the failure stage, and the corresponded damage quantity is about 0.4, which agrees well with the theoretical research. The study reveals the critical problem of sandstone failure in the damage process.

Joint Actuated Torque Optimization Technique Applied to Space Manipulators via PSO Algorithm

XIN Peng-fei, RONG Ji-li, WU Zhi-pei, XIANG Da-lin, YANG Yong-tai

2017, 37(8): 813-817. doi:10.15918/j.tbit1001-0645.2017.08.008

Abstract(1181) PDF(807)

Abstract:
In this paper absolute nodal coordinate formulation (ANCF) was utilized to model space manipulator links and natural coordinate formulation (NCF) was adopted to model manipulator joints to develop the dynamic equations of a rigid-flexible coupling space manipulator system. Joint rotation trajectories containing the self-movement term were deduced from the predetermined end-point trajectory by inverse kinematics theory. Inverse dynamics of the manipulator system based on Lagrange multiplier in dynamic equations leads to joint actuated forces/torques applied to bearing shells and journals during the movement. Thus particle swarm optimization (PSO) algorithm with constriction factor can be employed to optimize the redundant self-movement term to obtain the minimum energy consumption of actuated torques, which forms a new joint actuated torque optimization technique applied to redundant space manipulators. The three-link planar manipulator was used to evaluate this method. Simulation results show that the proposed method is effective in the end-point trajectory tracking and in reducing energy consumption; the computed joint torques obtained are well continuous and suitable for practical engineering.

CSI Feedback for Imperfect Multi-Polarized Massive MIMO System

ZHENG Feng, CHEN Yi-jian

2017, 37(8): 818-823. doi:10.15918/j.tbit1001-0645.2017.08.009

Abstract(1045) PDF(949)

Abstract:
The leakage between two polarization directions can be substantial if the number of transmit antennas (Tx) at eNodeB increases significantly. As a result, these codeword models may not be as efficient as in current MIMO system. In this paper, the characteristics of practical dual-polarized massive MIMO system with imperfect channel was investingated. To improve CSI accuracy, a multi-component feedback scheme was proposed, in which two CSI components target the perfect part and imperfect part of polarized channel respectively. A linear combination of the two components was assumed at both eNodeB and UE. Moreover, efficient feedback models were also formulated for the two parts. Finally, the performance of the proposed scheme is evaluated through extensive simulation.

Finite Time Stabilization of Unmanned Platform Based on Nonlinear Disturbance Observer

HUA Yu-long, REN Hua-lin, SUN Wei, GUO Xiao-lin, CHI Bao-shan

2017, 37(8): 824-829. doi:10.15918/j.tbit1001-0645.2017.08.010

Abstract(984) PDF(949)

Abstract:
The finite time stabilization was discussed for an incomplete symmetry unmanned platform under a model perturbation and environmental disturbance condition. Due to the non-diagonal inertia and damping matrices existing in the original model, the investigated model was converted into two cascade subsystems with the global diffeomorphism transformation just for once to simplify the process of calculations. For these subsystems, a finite time convergence controller was developed based on a terminal sliding mode and back-stepping technique to improve the robustness and convergence speed. Introducing a first order low-pass filter, the composedness controller was optimized to prevent the saturation of the actuator. A new nonlinear disturbance observer was designed to estimate and compensate the perturbations and disturbances for the improvement of the controller's robustness without the definite boundaries of the estimation errors. Finally, the system was proved to be mean-square stable based on the Lyapunov theorem. The simulation results validate the effectiveness and robustness of the proposed controller.

A Signal Extraction Method for Vibratory Gyro with the Conical Shell Resonator

LIN Zhen, FU Meng-yin, DENG Zhi-hong, SHANG Jian-yu

2017, 37(8): 830-835. doi:10.15918/j.tbit1001-0645.2017.08.011

Abstract(1223) PDF(1086)

Abstract:
In this paper, a signal extraction method of solid vibratory gyro with conical shell resonator was presented. This kind of conical shell resonator removed the isolation holes between piezoelectric electrodes. Firstly, the principle of the gyro was analyzed. Then the gyro's circuit system and algorithm was designed. The vibration excitation part took an independent DDS module as an accurate excitation signal source. The vibration signal was sampled after treating with analog filter. The vibration controlling and angular calculating were finished in DSP. The orthorhombic interference signal, which caused by the electrodes on sensing axis of the resonator without the isolation holes, was analyzed. According to the result of experimentation, a way can be presented to calculate the input angular speed by using the phase angle of vibration signal. The research achievement can provide a reference for a new vibratory gyro.

A Novel Capacitor Voltage Control Strategy of MMC Applied for Permanent Magnet Synchronous Motor Drive

TAI Bing-yong, GAO Cong-zhe, LIU Xiang-dong, CHEN Zhen

2017, 37(8): 836-841. doi:10.15918/j.tbit1001-0645.2017.08.012

Abstract(1039) PDF(1024)

Abstract:
In order to improve the control performance of permanent magnet synchronous motor (PMSM) drive based on modular multilevel converter (MMC), a novel capacitor voltage control strategy of MMC applied for PMSM drive was proposed in this paper. With which the capacitor voltage of a sub-module was controlled to high or low flexibly according to the motor speed, and a mathematical analysis model of the flexible control strategy was also developed. Compared with the capacitor voltage stability of the traditional control, the control dimension of the novel control strategy was increased. With the proposed control strategy, the efficiency and precision of the output of the converter could be improved significantly. A laboratory prototype of a five-level MMC-based PMSM drive was built and experiments were carried out. The validity of the control strategy under steady and dynamic states was verified.

Robust Overlapped Gauge Feature Descriptor

ZHANG Yan, SUN Shi-yu, LI Jian-zeng, LI De-liang, DU Yu-long

2017, 37(8): 842-847. doi:10.15918/j.tbit1001-0645.2017.08.013

Abstract(1136) PDF(1244)

Abstract:
To improve the discrimination and invariance of feature descriptor, a robust overlapped gauge feature descriptor (ROGFD) was proposed. Firstly, the image grads was computed with Scharr algorithm and the second partial gauge derivatives were applied to enhance invariance of feature descriptor, and avoid the affection of Gaussian filtering on the feature descriptor efficient. Then the overlapped grids were constructed to enhance robust of feature descriptor by improving continuity of grids. Finally, the descriptor vector of length 64 was created by weighted summation and normalization of responses in neighborhood of key point. The experimental results of the recall vs. (1-precision) graphs and time show that, comparing with the state-of-the-art methods, the ROGFD reveals stronger robustness.

Echo Signal Simulation of Frequency Step-Scanned IPDA Lidar and Error Analysis for Space-Borne CO₂Detection

CHEN Si-ying, MA Yang, GUO Pan, ZHANG Yin-chao, CHEN He

2017, 37(8): 848-852. doi:10.15918/j.tbit1001-0645.2017.08.014

Abstract(957) PDF(1604)

Abstract:
A frequency step-scanned IPDA lidar was designed for space-borne CO₂detection. Compared with single on-line wavelength IPDA lidar of ESA, the distributed wavelength sampling across the line region could reduce the impacts of wavelength dependent responses on the lidar and also reduce the relative error. The echo signal, relative random error, frequency drift error and pressure uncertainties error as a function of the on-line wavelength with one scanned cycle was simulated. The total CO₂concentration relative error is 0.084 2% with 0.035 sr^-1reflectivity, 0.3 MHz frequency drift error and 0.001 pressure uncertainties error when the on-line wavelength stepped in 6 361.235 0 cm^-1. The results show that compared with 1.0×10^-6accuracy of single on-line IPDA lidar, the measurement error of space-borne CO₂wavelength step-scanned IPDA lidar is less than 0.5×10^-6.

Enhancement of the Underwater Range-Gated Degraded Image

XU Ting-fa, SU Chang, LUO Xuan, BIAN Zi-yang

2017, 37(8): 853-857,862. doi:10.15918/j.tbit1001-0645.2017.08.015

Abstract(1062) PDF(882)

Abstract:
A new twice image enhancement method was proposed to solve the problems of large noise, uneven illumination and poor contrast in the underwater range-gated image. Firstly, the problems of background noise's over enhancement and the gray level isolated degeneracy in the normal histogram equalization method were focused. Based on the improved image's global two-dimensional histogram transformation, the double platforms histogram equalization was added to achieve the goals that all the object, background, and boundary information were enhanced respectively. A custom suppressed estimated deviation parameter was appended to enhance the image twice in the framework of non-iterative Retinex transformation using the guided-filter to suppress the background noise and balance the image brightness. Simulation experiments' results show that the entropy index is increased by 15%, the statistical evaluation index is improved by 28%, and the noise suppression index is improved by 12% comparing with various algorithms. The effect of underwater range-gated image enhancement method is obvious and can reach the application requirement.

Power Wireless Transmission Control Method for Fuze Inductive Setting with Generalized Detuning Quantity

CHANG Yue, ZHOU Xiao-dong, LI Jie

2017, 37(8): 858-862. doi:10.15918/j.tbit1001-0645.2017.08.016

Abstract(1017) PDF(815)

Abstract:
In order to solve the problem of energy wireless transmission efficiency reduction in the process of fuze inductive setting, a wireless power transmission self-adaptive control method of fuze was proposed based on the generalized detuning quantity of the coupling loop. Firstly, the mathematical model of the secondary loop current was constructed to be used for the proposal of self-adaptive control method. Then, the control signals of voltage-controlled-oscillator was generated by testing the current rate based on the generalized detuning quantity of the coupling loop to maximize the secondary circuit current so that wireless energy transmission would be controlled adaptively. Finally, secondary coil feedback hardware circuit was constructed based on the equivalent secondary loop, and the method was also verified by experiments. The experimental results show that the control method is feasible and effective.

A Method for Feature Extraction in KECA Feature Subspace Based on Adaptive Kernel Learning

ZHANG Wei, XU Ai-qiang, PING Dian-fa

2017, 37(8): 863-868,874. doi:10.15918/j.tbit1001-0645.2017.08.017

Abstract(826) PDF(502)

Abstract:
Kernel-based attribute reduction methods have shown great advantages for removing redundant information and adjusting nonlinear structure of input data. But in real applications, it is difficult for kernel-based attribute reduction methods to select optimal parameters. To do this, a new feature extraction method based on the optimization learning of adaptive kernel function was proposed in this paper. By use of improved Fisher kernel matrix measure criterion, an optimization framework of adaptive kernel function was established to deal with multi-classification task. Combining with optimization results, eigenvectors which make greater contribution to Renyi entropy estimation of input data were selected. New features were extracted based on selected eigenvectors in KECA feature subspace. Experimental results show that presented method can not only enhance the classification accuracy, but also restrain noise interference.

Study on Synthesis and Hydrogelation of Hydrogelators Based on Cyclo(L-Lys-L-Lys)

ZONG Qianying, YE Lin, ZHANG Ai-ying, SHAO Zi-qiang, FENG Zeng-guo

2017, 37(8): 869-874. doi:10.15918/j.tbit1001-0645.2017.08.018

Abstract(864) PDF(938)

Abstract:
Fmoc mono-substituted cyclo(L-Lys-L-Lys) (FL-NH₂) was fist synthesized under strict control of the feed ratio. Thereafter, FL-NH₂was further reacted with cyclic anhydrides, in which three thermo-reversible low molecular weight hydrogelators were obtained. A study on the impact of the aliphatic chain length of cyclic anhydrides on the gelation performance was carried out. In particular, the glutaric anhydride acrylated derivative (FL-Ga) shows a better hydrogel ability. The TEM and SEM observations reveal that the resulting hydrogelators are self-assembled into fibrous aggregates,which are further closely intertwined to form a 3D supramolecular network structure. The hydrogen bond and π-π stacking interactions play a cooperative role during the self-assembly of hydrogelators. Based on XRD patterns of the xerogel prepared from the hydrogel of FL-Ga and Rietveld method, a possible molecular packing model of single layer membrane was also deduced.

Study on Pharmacokinetics and Excretion of Loureirin B in Rats Under Simulated Weightlessness Condition

CHEN Bo, ZHANG Yu-shi, SU Jing, WANG Rui, DENG Yu-lin, LI Yu-juan

2017, 37(8): 875-880. doi:10.15918/j.tbit1001-0645.2017.08.019

Abstract(1047) PDF(747)

Abstract:
To study pharmacokinetics and excretion difference of loureirin B (LB) in rats after single oral administration between simulated weightlessness and gravitation condition, a series of test was executed. Rats were tail-suspended for 21 days to simulate weightlessness effect. After a single oral administration of 25 mg/kg LB, venous blood and excretion samples were collected at different time points. Concentration of LB in samples was determined by HPLC-MS method. Pharmacokinetic parameters and excretion amount were calculated. Results show that, compared with normal gravity rats, the area under cuve (AUC_0-t), maximum concentration (C_max), time to peak concentration (t_max), volume of distribution (V_d), elimination rate constant (K_e), and biological half-life (T_1/2) of simulated weightless rats ware significantly changed. Meanwhile, the excretion of LB in urine, feces, and bile are also up-regulated in simulated weightlessness group, while no obvious differences are observed.

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