bob手机在线登陆学报自然版

2022, 42(5): 1-2.

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Abstract:

Investigation on Deformation Field Measurement of Nuclear Graphite Considering Mechanics Constraints

WANG Lu, YI Yanan, LIU Guangyan, MA Qinwei, MA Shaopeng

2022, 42(5): 447-452. doi:10.15918/j.tbit1001-0645.2021.050

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Abstract:
Accurate measurement of the deformation on the surface of nuclear graphite is of great importance to study its mechanical properties. The boundary deformation near specimen edges cannot be accurately obtained using the subset-based digital image correlation (DIC) method, and the measured deformation field does not satisfy spatial continuity. Thus, it cannot reflect the real deformation of the nuclear graphite specimen. In order to improve the measurement accuracy and achieve the boundary deformation measurement, a new DIC method with mechanics constraints (MC-DIC) was developed in this paper. In this method, 8-node quadrilateral elements with spatial continuity were used to reconstruct the deformation field based on the trust points obtained from the subset-based DIC. The results indicate that compared with the subset-based DIC method, the MC-DIC method is more suitable for non-uniform deformation measurement, and can more accurately measure the whole field deformation of nuclear graphite specimens under loads.

Damage Characteristics of Corrugated Steel Concrete Slab Under Contact Explosion Load

YANG Chengfeng, YAN Junbo, LIU Yan, LÜ Zhongjie, HUANG Fenglei

2022, 42(5): 453-462. doi:10.15918/j.tbit1001-0645.2021.108

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Abstract:
In order to explore the damage characteristics of reinforced concrete slabs strengthened with corrugated steel, reinforced concrete target slabs strengthened with corrugated steel were designed, and contact explosion experiments on corrugated steel reinforced concrete slabs were carried out. The typical damage characteristics of components were obtained, and the anti-explosion performance of reinforced concrete slabs strengthened with corrugated steel was demonstrated. Combined with the finite element software LS-DYNA, the failure modes of corrugated concrete slab, concrete slab and flat steel plate concrete slab with equal quality were compared, and the excellent anti-explosion performance of corrugated steel reinforced concrete slab was illustrated; the mid-span displacement of corrugated steel reinforced concrete slab under different contact explosion loads was obtained, and the weak direction of corrugated steel reinforced concrete slab under contact explosion load was given. Based on dimensional analysis, the engineering empirical formula of dimensionless mid-span displacement with respect to explosive quality is established.

Test and Evaluation of Ballistic Helmet Performance Based on 3D-DIC Technology

WEN Yaoke, LI Zixuan, YAN Wenmin, ZHANG Junbin, CUI Guangyu, LIU Fei

2022, 42(5): 463-470. doi:10.15918/j.tbit1001-0645.2021.104

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Abstract:
In order to study the transient mechanical response of the ballistic helmet in the case of non-penetrating and the severity of behind helmet blunt trauma (BHBT), an experimental study was carried out using 3D-digital image correlation (3D-DIC). The dynamic back face deformation (BFD) of the helmet, the deformation speed and the deformation area during loading were obtained. Based on these results, the blunt criterion (BC) and the abbreviated injury scale (AIS) were adopted to evaluate the degree of BHBT. The results show that the average maximum height of BFD is 27.8 mm, and the average static height of BFD is 9.5 mm. The gap between the helmet and the skull has a significant effect on the severity of BHBT. When the gap is 12.7 mm, the average AIS score is 5, and the average skull fracture probability is 22.3%; when the gap is 15 mm, the average AIS score is 2%, and the average skull fracture probability is 3.8%.

Influence Factors on Formation of Quasi-Spherical Explosively Formed Projectile

LI Yuan, XIE Jiangliang, ZHANG Haoyu, WEN Yuquan

2022, 42(5): 471-478. doi:10.15918/j.tbit1001-0645.2021.147

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Abstract:
Compared to the stem shaped explosively formed projectile (EFP), the quasi-spherical EFP represents the advantages of insensitivity to the flying attitude, better penetrability and enhanced aftereffects. In this paper, a verified numerical model was used to study the influence factors of charge length-diameter ratio, liner inner radius, liner outer radius, and liner central thickness on the evaluation indexes of EFP velocity, specific kinetic energy and length-diameter ratio, aiming to develop a new formation method based on a non-uniform liner. The results show that the relative formation rules are different from that of the spherical EFP with baffle ring and that of the long EFP with the same liner and charge structures. The explosive formation process with quasi-spherical EFP is simple and the shape and the penetrability of the EFP can be improved. This research can provide valuable references for the design and optimization of quasi-spherical EFP.

Storage Life Evaluation of Solid Propellant Under Alternating Temperature Conditions

DONG Haiping, ZHANG Jingjing, WEI Xiaoqin, ZHAO Fangchao, LU Wei, LI Han

2022, 42(5): 479-484. doi:10.15918/j.tbit1001-0645.2021.145

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Abstract:
A life evaluation method based on modified Coffin-Manson model was proposed for the solid propellant stored in alternating temperature environments for a long time. Firstly, based on the temperature cycling acceleration degradation test data, the performance degradation curve of a solid propellant at different accelerated stress levels was obtained by the linear regression method. Then, combined with the failure threshold, the pseudo life at different acceleration stress levels was calculated according to the performance degradation model at the corresponding acceleration stress level. Finally, a multiple regression method was used to determine the acceleration model—modified Coffin-Manson model, which can be used to extrapolate the storage life of a solid propellant stored at room temperature. The storage life of a solid propellant is 16.7 years at room temperature by this new method. Compared with the actual storage life, the error is about 7.22%. The result indicates that this method is effective and feasible and can be applied to evaluate the storage life of other solid propellants or ammunition stored in an alternating temperature environment for a long time.

Stability Analysis for Structural Parameters of Human-E-Bike System

HUANG Hua, YAN Juntao, ZHANG Jun

2022, 42(5): 485-492. doi:10.15918/j.tbit1001-0645.2021.133

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Abstract:
A comprehensive and complete dynamics equation was established for a rider-E-bike system based on the global structural parameters of the E-Bike and the factors, including rider parameters, road slope and external loads. According to the eigenvalues of the second-order differential equation, the stability of the rider-E-bike system was analyzed, and based on the analysis results the cycling speed range of the rider-E-bike system was divided into five kinds. And then, six stability indicators were defined to analyze the influence of different structural parameters on system stability. Finally, two non-dimensional indicators, namely regional sensitivity index and interval speed sensitivity index, were introduced to characterize the influence of structural parameters on different mode regions and self-stability of system. Based on the relativity analysis, the interval speed sensitivity index was classified for correlation area and the relationship between different structural parameters and self-stability performance of the system was defined. The results show that the main structural parameters of the system、parameters of the rider and different road slope angles have significant differences in the degree of influence of the system speed range and system self-stability. The sensitivity indicators can be used to characterize the degree of influence of the system structure parameters on the system stability, the size of the sensitivity parameter can reflect the strength of the system stability.

Structural Parameters Design of Rescue Manipulator Based on Multi-Objective Optimization

ZHAO Jiangbo, XIU Bingkai, WANG Junzheng, ZHANG Xin

2022, 42(5): 493-501. doi:10.15918/j.tbit1001-0645.2021.082

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Abstract:
In order to achieve the comprehensive optimization of the dual-arm rescue robot’s working space, load capacity of robotic arm and speed of manipulator’s end-effector in rescue engineering, a structure parameter design method was proposed based on multi-objective functions for rescue robot to carry out comprehensive optimization. To overcome the difficulty of mathematical description of the dual-arm working space, load capacity and speed of manipulator’s end-effector, a triple integral method and manipulability function were used to establish their objective functions respectively. To optimize the three objective functions synthetically, a coupling analysis method was proposed, and the coupling relationship between the three optimization objectives was determined. Using the fuzzy analytic hierarchy process (FAHP), multiple optimization functions were linearly weighted according to the index weight to obtain a comprehensive multi-objective optimization function. Based on the comprehensive optimization function, the optimal value of the objective function was solved based on the particle swarm optimization (PSO), and the dual-arm structural parameters were obtained, so that the comprehensive performance of the dual-arm rescue robot was optimized. The simulation results show that the performance index and optimization method of the proposed dual-arm rescue robot are feasible.

Image Stitching Method Based on Global and Local Features

XU Xiangyang, YUAN Shanshan, WANG Jun, DAI Yaping

2022, 42(5): 502-510. doi:10.15918/j.tbit1001-0645.2021.093

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Abstract:
To solve the error accumulation problem in the traditional sequential image stitching algorithm, a new image stitching method was proposed based on global and local features. Both one global image with large field of view and low resolution and some local images with small field of view and high resolution were taken simultaneously. Then, substituting deep learning for the traditional algorithm, the matching points of the two were extracted. And according to their area ratio, the matching point coordinates of the global image were scaled up at the same proportion for the purpose of projecting local images to the plane of the global image without scaling. Finally, the overlapping areas of local images after projection were fused and stitched to form a panoramic image with large field of view and high resolution. Experimental results show that deep learning can achieve feature matching quickly and accurately. Moreover, the local images are independent of each other, effectively solving the restriction of stitching sequence and the accumulation of stitching errors.

Research on Optimal Guidance Strategy of Terminal Speed Control Based on LSTM

WEN Qiuqiu, HUANG Wenyu, LU Baogang

2022, 42(5): 511-522. doi:10.15918/j.tbit1001-0645.2021.028

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In response to the need for terminal speed control of hypersonic aircraft, the dimensionless overload characteristics of the guidance law were analyzed firstly on the basis of the optimal guidance law for landing angle constraints. The analysis results show that the guidance parameter adjustment can impact on the terminal speed. And then a terminal speed control strategy was proposed for the guidance law, and based on this, an online guidance law design strategy was proposed to adapt aerodynamic deviation. On this basis, a long short-term memory (LSTM) deep neural network algorithm was used to carry out online design algorithm of the guidance law parameters. Finally, a trajectory simulation was carried out to verify the online design algorithm of designed guidance parameter. The simulation results show that under the premise of ensuring the terminal accuracy and landing angle within the index requirements, the proposed method can significantly improve the ability of terminal speed control.

Research on Integrated Design of Aircraft Spiral Maneuver， Guidance and Control Based on Sliding Mode Control

WU Yanxuan, LU Xutan, WANG Zhengjie

2022, 42(5): 523-529. doi:10.15918/j.tbit1001-0645.2021.089

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To solve the problems of the capability deficiency of air-to-ship aircraft in the terminal guidance process and the inefficient control due to the separation of guidance and control loop design with unsatisfied assumption of bandwidth separation, an integrated design method was proposed for the guidance and control loop of the aircraft. Taking a ballistic maneuvering form with three-dimensional spiral maneuver, the design method was arranged to achieve spiral maneuvering, guidance and control integration. Firstly, an integrated model was established for the guidance and control loops at the end of the flight. And then, a sliding mode control method was applied to complete the control law design for guidance and control integration. Finally, introducing a period inclination rate of the line of sight obliquity and the line of sight deflection rate, the integrated design was carried out for spiral maneuvering, guidance and control integration. The simulation results show that the control law designed in this paper can improve the strike accuracy and provide a ballistic spiral maneuverability in the attack process.

Rapid Initial Alignment of MIMU with Unknown Roll Angle of the Trajectory Correction Fuze

JIN Lei, HU Baoyuan, SHEN Qiang, WANG Hanyu, DENG Zilong

2022, 42(5): 530-535. doi:10.15918/j.tbit1001-0645.2021.058

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To solve the problem of unknown roll angle of correction fuze in the two-dimensional trajectory correction projectile with dual-spin structure after launch, a method was proposed, using back propagation (BP) neural network to determine the roll angle range of correction fuze for coarse alignment, and then using the satellite navigation system to assist inertial navigation system for rapid initial alignment. Considering the relation between the roll angle error of correction fuze and velocity error of inertial navigation, a neural network model was established and trained with different simulated trajectories of multiple working conditions. The simulation results of spinning projectile trajectory show that the error of estimated roll angle of correction fuze is less than 20° during coarse alignment process when using medium precision MIMU and the error can converge to less than 0.4° within 40 s after launch during fine alignment process.

A Design of a 2 bit/cycle SAR ADC Design with Noise Shaping

CHEN Zhiming, GAO Yige, ZHANG Lei, WANG Xinghua

2022, 42(5): 536-542. doi:10.15918/j.tbit1001-0645.2021.337

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An 8-bit 100 MS/s successive approximation register analog-to-digital converter (SAR ADC) with 2 bit/cycle structure was designed for 180 nm CMOS process. Two DAC capacitor arrays, SIG_DAC and REF_DAC, were used to implement 2 bit/cycle quantization. Upper plate sampling technique was adopted to greatly reduce the number of capacitors in SIG_DAC. Split-capacitor structure and optimized asynchronous SAR logic were arranged to improve the conversion speed of ADC. A noise shaping technique was applied to effectively improve the signal-to-noise-distortion ratio (SNDR) of the ADC at oversampling. The results show that without noise shaping, the proposed ADC can get 46.22 dB SNDR at 100 MS/s rate with 1.8 V supply voltage. Through noise shaping, the simulation results show the SNDR is increased by 11.27 dB to 57.49 dB at an over-sampling rate 10, which means the ENOB of ADC is increased by 1.88 bit and reaches 9.26 bit.

Novel Noise-Robust and Fast Reconstruction Method For 3D Magnetic Particle Imaging

SHI Yueting, REN Shiwei, WANG Xiaohua

2022, 42(5): 543-550. doi:10.15918/j.tbit1001-0645.2021.308

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To improve the 3D imaging and reconstruction speed of Magnetic Particle Imaging (MPI), reduce the requirement of 3D refactoring to the completeness of sampled projection data, a novel Noise-Robust 3D Sparse Sampling Magnetic Particle Imaging (3D NRSS-MPI) method was proposed. The algorithm was arranged to reconstruct 3D MPI noisy data by solving a convex optimization problem formed with the l₂norm and sparse regular constraint of MPI projection imaging. Eliminating the limit of MPI scanning trajectory, the proposed method was designed as a universal basic model for the developing MPI technique. Taking the advantage of MPI priori information to improve the 3D reconstruction robustness of noisy MPI projection data, 3D total variation sparse operator was established to realize matrix-free operation, improving the efficiency of operation. The results of point source and coronary phantom imaging experiments show that the proposed 3D NRSS-MPI method can effectively eliminate the reconstructed image star artifacts at 1/4 undersampling, obtain a higher image signal-to-noise ratio, and make the coronary reconstruction structure similarity exceed 0.701, which can accurately reconstruct the undersampled and noisy MPI data, effectively shortening the imaging and reconstruction time by 4 times.

Correction of Residual Overlap for Temperature Measurements from Raman-Mie Lidar

CHEN Siying, NIAN Xuan, CHEN He, ZHANG Yinchao, GUO Pan

2022, 42(5): 551-556. doi:10.15918/j.tbit1001-0645.2021.141

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The overlap functions of high- and low-order channels from Raman-Mie lidar are different due to the influence of optical devices and detectors in each channel, which will cause errors in temperature measurement near the ground. In order to solve this problem, a new method to correct the residual overlap of the temperature measurement channel was proposed. This method firstly calculated the ratio of the effective differential scattering cross section of the high- and low-quantum number Raman signals through the radiosonde temperature and the calibrated normalized spectral transmittance, and then the residual overlap profile was calibrated by the Raman signal intensity ratio. The effectiveness of this method was verified by the experimental data of Raman-Mie lidar. The results show that the effect of overlap on temperature retrievals can be exactly corrected using the new method, and can significantly improve the accuracy of temperature inversion near the ground, and enhance the detecting performance of pure rotational Raman-Mie lidar in the boundary layer.

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2022 Vol. 42, No. 5

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