bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental study of hot pressed sintered modified materials
Authors: Tang X Z , Wang Z J , Yi JY , Han Y Y , Wang Y F , Jia Z J 
Published: July 2020

Abstract
The PTFE/Cu composite powder was selected as the experimental raw material, and the modified material PTFE/Cu with dense structure was prepared by hot pressing sintering process. The morphology of the product before and after the test was compared and observed by SEM. The effect of different material ratios on the densification results of the powder was studied, and the difference between molding and hot pressing sintering was analyzed. The results show that hot-pressed sintering can produce modified PTFE/Cu with a density of up to 99.9%, which is higher than that obtained by molding under the same pressure. The SEM image shows that, unlike the molding, hot-pressing sintering makes the crystal grains of the two materials exist independently in the modified polymer, and makes the powder crystal grains gradually perpendicular to the hot pressing direction.
Research on damage of typical water-containing composite structure under different types of charge
Authors: Wang C L , Zhou G , Ma K , Li M , Chen C L , Feng N , Ke M 
Published: July 2020

Abstract
The damage of the water-containing composite structure subjected to underwater explosion is caused by multiple damage elements, such as charge structures, water-containing composite structure, experimental mode and so on. The underwater explosion experiments and the numerical calculations have been performed to study the damage of water-containing composite structure under the different kinds of charge underwater explosion and under different experimental mode, The result shows that the damage of structure under the action of shaped charge is more serious than that of blasting charge in the case of the same charge equivalent. The combined action of shaped penetrator and shock wave can cause perforation and plastic deformation of the rear plate and target of the water-containing composite structure e. The tearing hole on the front board is 2∼3 times of the shaped charge diameter. The damage of the rear plate is the penetration of the penetrator which is about 1/3 times of the shaped charge diameter. When shaped charge explodes in air or underwater, the plastic deformation of the rear plate is very different.
Research on the SDT technology based on a two-stage structure
Authors: Xian M C , Meng Y G , Xie J Y , Wu L Z , Shen R Q 
Published: July 2020

Abstract
The SDT (shock to detonation transition) technology based on a two-stage structure has been researched. The models of mass block’s velocity and shock-wave convergence produced from mass block impacting charge have been built, which reveal the mechanism of detonation caused by the impact. The influence characteristics of some parameters on the shock-wave convergence have been obtained. According to the analysis, the related parameters have been decided and the grope experiments were carried out. The result shows that the detonator employing the SDT structure, whose igniting time is less than 2ms, has good environmental adaptability. The technique of reliable and fast detonation of high explosive without using sensitive explosive has been realized.
Mechanical properties of steel gun barrel processed by cold radial forging with stepped mandrel under different forgingratios
Authors: Yang Yuzhao , Zhang Xiaoyun , Fan Lixia , Xu Cheng 
Published: July 2020

Abstract
Mechanical properties of 30SiMn2MoVA steel gun barrel processed by cold radial forging with stepped mandrel under the different forging ratios were investigated in the present work. This work mainly reported the axial and circumferential mechanical properties of forged gun barrel before and after annealing. The axial and circumferential mechanical properties were measured by tensile test and bulging test, respectively. The results suggested that the strength was enhanced and elongation was decreased by forging which was caused by cold work hardening. After annealing, the anisotropy of elongation was observed. The circumferential elongation was weaker than the axial. With the increasing of forging ratios, strength anisotropy was exacerbated gradually. The circumferential strength was inferior to the axial. Besides, there were axial penetrating cracks in the failure state of circumferential bulging test specimens. Through the electron microscopic examination, the axial micro cracks and wrinkles in the inner wall of the forged tubes were observed. It showed that the cold radial forging with stepped mandrel may result in the defect in the inner surface of the gun barrel which should be paid attention.
Neural network based adaptive rise control of tank gun systems
Authors: Ma X , Deng W X , Yuan Sh S , Yao J Y , Yang G L 
Published: July 2020

Abstract
With the development of the all-electric fourth-generation tank, higher requirements have been put forward for the accuracy and response speed of tank gun control and the traditional tank gun system modeling methods and control strategies failed to meet the requirements. For this reason, a neural network based adaptive robust integral of the error sign (ARISE) control for tank gun system is proposed considering two-axis dynamic coupling and nonlinear friction characteristics. Firstly, a two-axis coupling nonlinear dynamic model of the tank gun system is established and a continuous static friction model is used to characterize the nonlinear friction characteristics of the system. Then, an adaptive law is designed based on the desired position instruction to realize the online update of unknown system parameters. In addition, the neural network is used to compensate other unmodeled dynamic errors and the influence of neural network approximation error is suppressed by the nonlinear integral robust control term. The stability analysis results show that the proposed neural network based adaptive robust integral of the sign of the error control strategy can obtain excellent asymptotic tracking performance, and the simulation results verify its effectiveness.
Discrete Element Simulation of Durability for Bionic Wheels of Mars Rover
Authors: Lin Y C , Yan Y P , Yuan B F , Liu Y F , Zou M 
Published: July 2020

Abstract
Four kinds of bionic surfaces (convex, scale-like, ribbed and concave shape) for Mars rover wheels were designed to improve wheel durability. A discrete element wheel-soil simulation system was developed, and three-dimensional discrete element analysis and soil bin tests were conducted. The results show that the masses of the convex and scale-like forms increased by 5.4% and 17%, respectively, and that the tangential cumulative forces decreased by about 40% and 70%, respectively. The wear mass decreased by 53% and 47%, respectively, compared with a prototypical wheel. The simulation shows that the durability increased significantly. The average tangential cumulative forces of the concave and ribbed shapes increased by more than 50%, and the wear mass decreased by 35% and 32%, respectively, compared with a prototypical wheel. The simulation shows that the results were not definitive. The analysis shows that the durability of the wheels can be improved via bionic optimization method. These results therefore provide a basis and reference for the design and optimization of the Mars rover’s wheel surface.
The fuzzy adaptive PID control of brushless DC motor
Authors: Yin H Q , Yi W J , Li C C , Wang K J , Wu J T 
Published: July 2020

Abstract
Brushless direct current motor (BLDCM) is a complicated system with multivariable, nonlinear and strong coupled. The present work devotes to design a fuzzy adaptive PID algorithm based on the speed loop so that it could crack the traditional PID problems which include bad parameter setting, poor adaptability, imprecise control and weak anti-interference so on. In this paper, the mathematical model and operating characteristics of BLDCM are analyzed. Then, the simulation platform is built by MATLAB/Simulink. Finally, the control effects of PI, PID and fuzzy adaptive PID are compared and analyzed. The results indicate that the fuzzy adaptive PID is better robustness, faster response, smaller overshoot and more stable operation than others.
Real-time instance-aware semantic mapping
Authors: Xu X C , Liu L l , Xiong R , Jiang L 
Published: July 2020

Abstract
The semantic information helps robots to understand its surroundings like human beings and enables robots to achieve human-robot interaction. In recent years, there have been many interests in semantic mapping. Numerous approaches manage to build a semantic map and achieve good accuracy, but the existing mapping methods which create the metric semantic map ignore the subsequent applications of the semantic map. However, the metric map with the simple semantic class label has no direct benefit to localization. In this paper, we propose an approach to construct an object-centric map with promising applications. Employing the traditional metric and deep learning methods, we can extract objects from the environment and along with semantics. This object representation of the semantic map can be useful in other applications of robots, our local map and global map framework can be useful for navigation. At last, we report on the quality and speed of our object-centric mapping method.
Effects of heat treatment and deformation on tensile strength and conductivity of Cu-Cr-Zr alloy doped with lanthanum and yttrium
Authors: Ren X Y , Gao P , Zheng H W , Yu W J , Wang S L , Lei Y , Yang Ch X , Lan L , Li YF 
Published: July 2020

AbstractCopper chromium zirconium alloy Cu-0.684Cr-0.077Zr-0.012La-0.020Y mixed with lanthanum and yttrium, after treatment at different solid temperatures, through metallographic microstructure and energy spectrum analysis, determine the alloy solid solution temperature is 920°C. After solution treatment at 920°C, the alloy underwent 40%, 60% and 80% deformation after quenching and water cooling, the results showed that after 60% deformation, 520°C and 0.5 hour aging treatment, the alloy could obtain better comprehensive performance, with tensile strength of 527MPa and electrical conductivity of 73%IACS.
Experimental study on fabrication and impact characteristics of PTFE/Al/W reactive materials with different molding pressures
Authors: Geng B , He S , Guo H , Cun H , Wang H , Ge C 
Published: July 2020

Abstract
Here we focus on the impact characteristics of polytetrafluoroethylene/aluminum/tu-ngsten (PTFE/Al/W) reactive materials under various molding pressures. Reactive materials of the density of 3.0 g/cm3 were fabricated via pressing and sintering processes. Drop weight tests were carried out to study impact characteristics of the reactive materials. Experiment shows that, critical forming pressure and compaction pressure are approximately 5MPa and 100MPa, separately, and meanwhile, the sintering cycle could enhance the strength of the material pressed under the critical forming pressure. Furthermore, reactive materials show strain rate effect on impact characteristics, and the increase of mounding pressure attributes to the transition from inertness to sensitivity of the material. Within the molding pressure range of 15MPa, impact sensitivity of the material increases exceedingly, whereas, the impact sensitivity remains relatively stable when the molding pressure ranging from 15 MPa to 100 MPa. Phenomenologically, with the increase of the molding pressure, the drop impact induced initiation flame transits from weak and unsustainable to intense and continuous. From the point of initiation mechanism, low molding pressure introduced high porosity plays negative role against the formation and growth of the hot spots in the microstructure of the material, which was demonstrated by the experiments. The conclusion drawn from this research reveals that a well pressed condition would be beneficial for increasing the impact sensitivities of low density reactive materials.
Research on processing technology of alumina ceramic interlayer composites
Authors: Ren W J , Li X , Shao H F , Hu G X , Shuai L , Cai C , Tuo S, R , Zou S J Y , Chen X D 
Published: July 2020

Abstract
Composite materials which the interlayer is alumina ceramics have the characteristics of high surface toughness, high hardness in the interlayer, high brittleness. To meet the precision of machining process, the quality requirement of the product surface and the requirements of machining processing schedule at the same time, it is difficult to process all kinds of angle and holes. Aiming to solve the difficulties in the processing technology of interlayer composite materials, the choice of machine, knife tools and the processing parameters, as well as the determination of process quality are researched deeply. Meanwhile, the equipment specifications, blade diameter, the relationship between cutting speed and the thickness of interlayer composite materials are all determined. The determination method of process quality is given by the section quality, size precision and the surface quality and other aspects. This paper can guide the processing of related defense composite materials.
Study on differential mode conducted interference of trigger circuit of high-power thyristors in pulsed power supply
Authors: Wei Jiu-fu , Liu Xiang-rong , Luo  , Li Zhen-xiao , Li Bao-ming 
Published: July 2020

Abstract
The trigger circuits of high-power thyristors in pulsed power supply (PPS) contain a large number of pulse transformers, switching MOSFETs (SMFETs) and other passive devices. Fast on-off of SMFETs and pulse transformers often lead to differential mode conducted interference (DMCI) problems in trigger circuits of high-power thyristors. This paper mainly disscusses DMCI problems in trigger circuits of high-power thyristors in the following aspects: initially, circuit models of high-frequency parasitic parameters of pulse transformer and SMFET are established; next, principles of DMCI in trigger circuits of high-power thyristors are investigated; furthermore, DMCI suppression methods are also analyzed; ultimately, experiments have been carried out to verify the theoretical analysis.
Research on a novel integral projectile combining of warhead and armature for the railgun
Authors: Tang B , Xu Y T , Wan G , Jin Y , Li H Y , Li B M 
Published: July 2020

Abstract
Railgun can accelerate the projectile to high speed. The common launching method is using an armature to propel the projectile. When the projectile flies out of the muzzle, armature and sabots are separated from the projectile which become the harmful fragments. Therefore, an integrated projectile which combines the flying warhead and armature is proposed in this paper. This integrated projectile has two advantages, one is that the combination of warhead and armature does not throw dangerous fragments at the muzzle, the projectile has low aerodynamic resistance and flies stability by rotation stability. Another advantage is that in exterior ballistics, the combination of armature increases the total mass of the flying body and may improve the range and damage power. According to the requirements of railgun launching and flight stability of exterior ballistics, structure of the integrated projectile is proposed. Computational fluid dynamics method is used to calculate the aerodynamic characteristics of the new integrated projectile, which is compared with NATO projectile. The calculation shows that the projectile has good aerodynamic characteristics. The rotational stability of the new projectile is calculated and the electromagnetic launch test is carried out. Research of this novel integral projectile will provide reference value for the application of railgun.
Modeling and numerical simulation on launch dynamics of integrated launch package in electromagnetic railgun
Authors: Lin Qinghua , Li Baoming 
Published: July 2020

Abstract
This paper presents a numerical approach to modeling launch dynamics of integrated launch package in railguns. This approach was based on the three-dimensional transient finite element solutions of the multi-physical field equations. Numerical simulations were conducted for a railgun system composed of the capacitor-based pulse forming network, advanced containment launcher, and integrated launch package. Some issues about induced eddy currents, stress distributions, and projectile lateral motions were discussed. The results show that the in-bore motion of the projectile is sensitive to the launch package configuration and launcher stiffness. Moreover, the armature under a heavy current is prone to serious deformation and then leads to launch failure. The launch dynamics model provides a method to predict the in-bore processes and evaluate the in-bore survivability of the integrated launch package in a railgun.
Firing range optimization of a 155mm uni-modular charge howitzer by ETC technology
Authors: Jin Yong , Ni Yanjie , Zhao Liangyou , Cheng Niankai , Wan Gang , Li Baoming 
Published: July 2020

Abstract
Electrothermal-chemical (ETC) launch technology can accurately control and enhance the ignition and combustion of solid propellants to improve the consistency and accuracy of ballistics. In this paper, a calculation model including the transient burning rate formula and six-degree-of-freedom rigid body trajectory equation is established to simulate both interior and exterior ballistics processes for a 155mm uni-modular charge howitzer. The simulation results show that the muzzle velocities are optimized via the ETC technology. The 155mm uni-modular charge ETC howitzer can effectively obtain the minimum range, increase the range overlap and maximum range, and improve the ballistic stability and consistency.
An initial velocity model study of electromagnetic railgun based on back propagation neural network
Authors: Liu J G , Dong Z Q , Ren R , Sh Ye W , Zhang C H , Li J H 
Published: July 2020

Abstract
The velocity of launch has been the key factor restricting the application of electromagnetic rail. For electromagnetic launch system, the structural parameters change directly or indirectly affect the Launching velocity of the electromagnetic launch system. In order to improve the initial velocity of the electromagnetic railgun. The mathematical model of electromagnetic rail gun launch was set up, the structure parameters of armature and the size of the pretension force between armature and orbital were variables, based on the target function, The equivalent model of rail gun BP neural network is established by using the calculation results of mathematical model, and the model of rail gun BP neural network was optimized by electromagnetic emission test data. The error of rail gun BP neural network model optimized by experimental data is 18.5% lower than that before optimization and 6.5% lower than that of experimental data. The results show that the launch speed of the optimized rail gun BP neural network model is closer to the actual speed.
Model updating of gun recoil mechanism based on time domain response
Authors: Liu J , Xu H Y , Zhou C J , L Y , Liu P K , He Q 
Published: July 2020

Abstract
For gun launching dynamics modeling, the accuracy of the recoil and counterrecoil model is important. In order to improve the accuracy of gun recoil mechanism modeling, the rigid-flexible coupling firing dynamics model of a small-caliber gun was established, and the recoil displacement of the gun was tested by live firing test. Aiming at the error between the simulation curve and the test curve of the recoil displacement changing with time, taking the correlation coefficient of the two curves as the objective function, the dynamics model of the recoil mechanism was modified based on the time-domain response using the optimization algorithm. The modified results show that the difference of the maximum recoil displacement decreases from 9% to 0.1%, and the similarity between the simulation curve and the test curve reaches 0.99. The modified results based on the time-domain response effectively improve the accuracy of the recoil model, so that the established dynamics model can more truly reflect the dynamic characteristics of the recoil mechanisms, and provide the basic conditions for ensuring the simulation accuracy of the launch dynamics model.
A study on finite element model updating method for recovery airbag
Authors: Li J Y , Song S P 
Published: July 2020

Abstract
It needs FE(finite element) model updating of recovery airbag for improving simulation accuracy of cushion process. In this paper, the FE model was updated based on drop tests of payload-airbags system. Firstly, FE model of payload-airbags was established. Two parameters, include discharge coefficient of vent and friction coefficient between airbag and ground, were selected for updating by sensitivity analysis. The response surfaces of impact response vs the two parameters were established based on Design of experiments and FE model. Based on the response surfaces, the optimal solutions were solved by Genetic algorithm. It indicated that the FE model updating of airdrop airbag was efficient through comparison of test results and simulate results before and after updating.
Damage evolution around shear loaded inter-void ligaments
Authors: Chen S , Osovski S 
Published: July 2020

Abstract
The dimpled fracture surfaces observed in a post-mortem investigation of the ductile fracture indicates that the fracture formed through coalescing voids that originated at the microstructural level. The damage process is commonly described by the nucleation and growth of those voids, thinning the inter-void material ligaments, ultimately leading to final fracture. The final stages of the ductile fracture process will be discussed, with emphasis on the local plastic deformation field in the void’s surroundings. This study considers dominant shear loading as the driving force for plastic deformation, using periodic cell calculations and the GTN model modified for shear damage. We systematically investigate plane strain and plane stress configurations, as a realization of the ligament thinning as part of the ductile fracture process. We suggest that the void surroundings and the intervoid ductile ligament undergoes an idealized gradual transition from plane strain to plane stress as the ligament gets increasingly thinner. While the present study addresses quasi-static failure, it is believed that the framework presented here can be extended to dynamic loading situations as well.
Fin stabilized projectiles point mass model
Authors: Meda Tomasz 
Published: July 2020

Abstract
To calculate flight of unguided projectiles several types of the flight models are used. The application mostly depends on demand of the model accuracy, complexity and computational cost. As a good compromise of these three features for flight calculation of spin stabilized projectiles Modified Point Mass Trajectory Model was created. The MPMTM is commonly used for firing tables creation. In the paper the author shown conception of flight model designed for fin (aerodynamic) stabilized projectiles. At In the first part of the paper the motivation of the model designing was explained. Additionally analysis of the phenomena that should be used in the model was made. In the next part of the paper main equations of the model were described. Some of them were empirical. In the third part of the paper the accuracy of the designed model and two other model types was compared. Calculations results were compared with experimental data and the conclusion were drawn.