bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization in the multi-cycle densification technology for manufacturing of the high density carbon fiber reinforced carbon
Authors: Ilyushchanka A Ph , Kryvanos A K , Prokhorov O A , Kryvulenka M U
Published: July 2020

Carbon fiber reinforced carbons (CFRC) are used to work in extreme environments because of their erosion resistance, ablative ability, and high mechanical characteristics at extremely high temperatures. The production of such materials includes several cycles of gas-phase or liquid-phase densification of initially porous carbon fibers reinforcement. The paper analyzes the main process parameters and densification routes, and their role in the manufacture of CFRC with high performance. A method for calculating changes in the density and porosity of CFRC during a multi-cycle densification has been developed. The results of the experiments confirmed the adequacy of this method.
Tests of thermal insulation properties of bakelite and glass-epoxy composite
Authors: Rybakiewicz L , Sokolowsk D
Published: July 2020

This paper presents tests results of thermal insulation of bakielite and epoxy resin with glass fibre. The tests were carried for the same thicknesses of different type of insulation materials and taking over the temperature through a steel plate under insolated material was measured. Based on the tests results material with better thermal insulation properties was chosen.
Special software design for data acquisition and experi-mental database management of electromagnetic launch system
Authors: Tian H , Xia Y , Huang F , Jin Y , Wan G , Ni Y J , Li B M
Published: July 2020

Electromagnetic launching system is composed of the Electromagnetic Railgun (EMRG) and the large-scale Pulse Power System (PPS). According to the different test requirements of PPS and EMRG, the special master-slave distributed data acquisition software for electromagnetic launching system is designed by using LabVIEW graphic language. The test host and the sub-machines are multi-channel transient data acquisition systems based on PXI bus. The host PXI is used to measure the comprehensive parameters of the EMRG in multi-physical field. All sub-PXIs are used to diagnose the discharge current signals of each Pulse Forming Unit (PFU). The database management software uses C# programming language to design a friendly human-computer interaction interface, and uses SQL Server software to establish and manage the database, which realizes the comprehensive management of experimental data, tasks and resources involved in the EMRG experiments. The experimental information and experimental data are classified and filed, and the experimental data can be queried, and the experimental results can be analyzed and compared. The data acquisition and experimental database management software has perfect functions, friendly user interface, convenient operation, good versatility, and can also be used in other experimental occasions.
Researches on the trigger pulse width’s compression of high power thyristor
Authors: Luo H G , Gu J L , Xia Y , Ge Ch M , Li X , Wang Sh Y
Published: July 2020

The width compression phenomenon of the trigger signal in triggering high power thyristor was first observed in the experiments. The trigger pulse was measured by the oscilloscope in the experiments. The experiments showed that with the increase of the voltage supplied to the thyristor from 1kV to 7kV, the width of the trigger pulse was compressed gradually from 70us(the width with no compression) to 45us. Then with the increase of work voltage from 7kV to 10kV the width of the trigger pulse was not compressed further. This research is very valuable for the design of the thyristor trigger signals.
Analysis on the Influence of Breech Voltage on the Pulsed Discharge Characteristics of Capacitive Pulsed Power Supply in EML
Authors: Li Zhenxiao , Hao Shuangpeng , Ma Fuqiang , Li Baoming
Published: July 2020

Corresponding to the different gradient of the ideal working current, the movement process of the armature in the railgun bore can be divided into rising phase, stable phase and decreasing phase. Based on the load characteristic and the lumped-element equivalent circuit of the railgun, the characteristics of the railgun’s breech voltage in above three phases were analysed. Under the condition that the size of the launching system is close to the same, the change ranges of the breech voltage of the augmented railgun is much larger than that of the simple railgun, and the breech voltage of the augmented railgun is a very high forward voltage in the rising phase. The influence of the breech voltage on the discharge characteristics of the capacitive pulsed power supply was studied. In the rising phase, the high breech voltage of the augmented railgun has a significant adverse effect on the pulsed discharge characteristics of the capacitive pulsed power supply whose pulsed forming net consists of a large number of pulsed forming units with small energy storage and high resonance frequency. As a result, part of the stored energy of the capacitive pulsed power supply cannot be used effectively, which leads to the decrease of the working efficiency of the launching system. Using the launching system with a 13-MJ capacitive pulsed power supply and a medium calibre augmented railgun, the launching simulation and test were completed, and the analysis was verified. The research has important enlightenment for improving the match between the capacitive pulsed power supply and the railgun.
Study on dynamic characteristics of micro gas turbine with load mutation of pulse generator
Authors: Liu Jiaxing , Fu Xin
Published: July 2020

Because of the sudden load phenomenon of the pulse generator, it is required that the gas turbine, as the primary energy source of the pulse generator, not only has certain stability, but also has good dynamic performance. In this paper, based on AMESim, the dual rotor micro gas turbine pulse generator set is modeled, calculated and studied the dynamic characteristics of the micro gas turbine in the case of sudden change of fuel quantity, and the effects of fuel increasing speed on the dynamic characteristics of gas turbine are studied with three different fuel supply strategies (a), (b) and (c).
Characteristic analysis of inductor in pulsed power supply changing with shape ratio
Authors: Hao Shuangpeng , Li Zhenxiao , Ma Fuqiang , Li Baoming
Published: July 2020

Solenoid inductor is an important component of pulse power source, its volume, electrical performance, stress and magnetic field generated during discharge directly affect the relevant parameters and performance of pulse power source. This paper presents a calculation model for solenoid inductor in pulsed power supply, given the inductance value and the wire, the volume, stress, resistance and external magnetic intensity of the five inductance values inductor under different shape ratio are calculated by changing the number of turns, and discusses and analyzes the changes and extremum in the volume, resistance, stress, and magnetic intensity of inductor with shape ratio. This article has certain guiding significance for the design of solenoid inductors.
Research on high-rate and repeat frequency discharge lithium battery for electromagnetic launch primary power supply
Authors: Ren Ren , Zhiqiang Dong , Jingang Liu , Weisheng Ye , Zizhou Su
Published: July 2020

Lithium battery with excellent comprehensive performance can effectively improve the firing frequency of railgun, firing times of railgun, system integration and security of electromagnetic launch weapon system. The development of lithium-ion batteries were introduced in this paper, mainly from the material system of lithium battery, analyzes all kinds of lithium battery, combined with electromagnetic emission weapon system for high voltage cascade characteristics of primary lithium battery power supply demand, points out the advantages and disadvantages of the lithium battery materials system, determine the improved after optimization of high ratio of lithium iron phosphate battery as primary power battery components. Two kinds of lithium batteries have been tested by high power discharge test, which proves that the high power lithium iron phosphate batteries have better performance. The high power lithium iron phosphate battery with soft package, high discharge rate, high power density and good security, can meet the requirements of high power, high power density and good integration of the primary source of electromagnetic emission.
Experimental Study on Plasma Ignited Single-base Propellant using SEM and EDS
Authors: Yang Chunxia , Jin Yong , Li Haiyuan , Yang Yong , Ni Yanjie , Li Zhenxiao , Li Baoming
Published: July 2020

To explore the reaction mechanism in the plasma-propellant interaction, plasma ignition and conventional ignition experiments are carried out on a single-base propellant. The samples after ignition are analyzed by scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS). Results show that the plasma jet brought a variety of high enthalpy flows into the propellant and deposited them on the surface of the propellant. These high enthalpy particles reacted with the propellant on the surface rapidly and produced voids and cracks different from the surface melting mode in the conventional ignition process. These voids provided microchannels for ignition and heat transmission. The area of ignition and combustion increased accordingly.
Research on armature vibration characteristics of electromagnetic gun’s extreme sliding electrical conta
Authors: Li Xiangjun , Wang Jun , Zhang Xianchun , Wang Sheng
Published: July 2020

The electromagnetic railgun is a new launch method that uses electromagnetic force to drive payloads and accelerate objects to super high speeds. In the electromagnetic railgun system, the armature is a key component that converts electrical energy into kinetic energy of projectile. It will vibrate when it moves between rails, and the vibration characteristic is the behavior when the armature slides along the rail. Armature vibration will affect firing accuracy, damage integrity of rail, and affect life of rail. Armature vibration may also cause arc discharge, which will damage the armature, consume energy, and reduce the launching efficiency of the electromagnetic railgun. In order to provide a more reasonable design for the armature, based on the finite element simulation software ANSYS, a modal analysis was performed on the armature during the launch process, and the possible modes of its free vibration were simulated. The analysis found that the vibration modes are mainly divided into translational movements along the X, Y, and Z directions and torsional movements along the X, Y, and Z axes. Whether or not the prestress is loaded on the armature and the magnitude of the prestress does not significantly affect its vibration mode. Changing the armature structure and materials will affect the vibration mode of the armature accordingly.
Analysis of firing after shortest distance between target and anti-aircraft gun
Authors: Wang J , Chang S F , Fan X C , Li X J
Published: July 2020

In order to make full use of the performance of high-muzzle-velocity anti-aircraft weapon, make full use of the target firing segments on the entire route of the target, fully grasp all the firing opportunities, and reduce the possibility of a target breaking through the defense, the original pre-navigation firing (firing before shortest distance between target and anti-aircraft gun) method based on a muzzle velocity below 3ma cannot meet the needs mentioned above. Based on the establishment of high-muzzle velocity projectiles, this paper aims at the current situation of less post-navigation firing (firing after shortest distance between target and anti-aircraft gun), verifies the feasibility of post-navigation firings by analyzing the relative remained velocity required to penetrate the target, and verifies that with the gradual increase in projectile muzzle velocity, its firing range and timing can increase simultaneously. It provides a theoretical basis for post-navigation firing, increases the firing opportunities for the target on the entire route, and provides a reference for the demonstration, design and testing of the new anti-aircraft fire control system.
An investigation on plastic deformation of rotating band for large caliber gun projectile during engraving process
Authors: Guo J H , Yao X F , Qiao J M , Li Y L , Zhang X D
Published: July 2020

The projectile engraving process of a large caliber gun is investigated by adiabatic process simulation based on smoothed particle hydrodynamics (SPH) and finite element method (FEM). The acceleration, velocity, displacement of the projectile are obtained, and the resistance force and moment applying on the projectile by the gun bore are also obtained. The resistance force varying with the travel of projectile is obtained and the curve reveal a peak in the particular position. At the beginning stage of the deformation, the force increased rapidly and then exhibits a slight transitional drop. The deformation process, equivalent stress, equivalent plastic strain, temperature and damage variable distribution of rotating band are obtained by numerical simulation. In order to visualize the simulation results, two kinds of post processing method are proposed. The frequency distribution of particles was get by particular variables, and the result showing that the maximum temperature of rotating band increment due to plastic deformation can be 150 degrees. Only few material can accumulated to the failure threshold, which indicates that large plastic deformation occurrences in rotating band while ductile fracture does no happen. The second method is to interpolate the field variable on a specified section by developing a program. The results show that the maximum equivalent stress is about 300MPa, the stress triaxility is less than zero, which indicates that most material under compression, and the maximum value of J3 related parameter is 0.5 located at rotating edge, which indicates material under shear loading, which agrees with the function of rotating band.
Numerical Study on Hydrogen Detonation Initiation through an Inhomogeneous Thermal Explosion
Authors: Da Chen , Jianguo Ning , Jian Li
Published: July 2020

Detonation initiation through an inhomogeneous energy source is studied using one-dimensional simulations. The energy source is divided into two segments, called segment A and segment B. The initial temperature and the length of two parts energy source are varied to provide different auto-ignition delay time and strength of the leading shock. Detailed chemical reaction mechanism is used for a stoichiometric hydrogen/oxygen mixture diluted by 70% Argon. According to the initial thermodynamic parameters, four different regimes of detonation initiation were found in the present study, namely high-critical, low-critical, low-subcritical and high-subcritical regimes. The critical temperature and internal energy in the inhomogeneous energy source to initiate the detonation are analyzed. It was found that, as we fix the length and temperature of segment B, by changing the temperature of segment A, there are two critical temperatures, called high critical temperature and low critical temperature. When the temperature of segment A higher than the high-critical temperature or lower than the low-critical temperature, there is no detonation occurs. As we change the length ratio of segment A and B, the same results was found. In addition, the relationship between the length ratio of segment A and B and the energy to initiate detonation are also studied.
Numerical simulation of the formation behavior of coated explosive formed projectiles
Authors: Yu Q B , Cun H , Xie J W , Wang H F
Published: July 2020

The formation behavior of coated explosive formed projectiles (CEFP) with different structure and material liners were numerically simulated by AUTODYN-2D. There are many factors affecting the coating effect of CEFP, the numerical simulation results show that the structure and liner material have remarkable influence on the velocity and forming effect of the CEFP. For the coating effect, the liner thickness has an optimum range. When the liner thickness is small or large, the explosive balls will deform seriously or not be wrapped sufficiently, and the EFP velocity decreases with increasing the axial thickness of the liner, when the liner thickness is 4.5mm and 5mm, the coating effect is the best. The curvature of liner also has an optimum interval, when the curvature of liner is small or large, the explosive balls will be lengthened or retrogradely compressed and destroyed, and the EFP velocity increases with the decreasing the curvature of the liner. When aluminum, iron, copper and tungsten are used as liner materials, the density and ductility of the material will affect the coating effect. The high density copper liner can achieve a good coating effect and well penetration performance.
A study on combat process simulation and casualty forecasting based on system dynamics
Authors: Peng B , Xu L , He Zh
Published: July 2020

The traditional casualty prediction method is of low accuracy, and there is no prediction of the detail time and place of the casualty. Moreover, there is no consideration of the real combat environment. This study uses system dynamics method to build casualty forecasting model, based on the dynamic combat process of red and blue troops to predict the temporal and spatial distribution of casualty. The simulation results are similar to the one actual case. Results show that the modern combat has short duration and the total number of casualties declined over the past but the casualty is concentrated in a short period of time, and attributed in wider areas. Air forces and relative military strength are the key influence factors for casualty. The use of system dynamics model for casualty prediction can significantly improve the pertinence and effectiveness of medical support.
Battery status estimation using extended belief rule base with novel rule reduction method
Authors: Zhu H Z , Xiao M Q , Li J F , Liu Zh Zh
Published: July 2020

The status estimation for lithium battery is playing more and more important role in preventing the catastrophic failure of the system. The traditional data-driven methods treat the battery status estimation as a black box, which denies interpretability of the health status estimation process. Originated from belief rule base(BRB) methods, the extended belief rule base(EBRB) broadened the possible application areas of BRB. By transferring measured data into extended belief rules, EBRB combines the advantages of accuracy from data driven methods and interpretability from belief rule based methods. This paper employs EBRB to deal with battery status estimation problem. Moreover, in this paper, we proposed a novel rule reduction method to optimize the performance of EBRB. The effectiveness of the proposed method is verified by the data of spacecraft applied batteries. Comparison among the proposed method, conventional EBRB and BP neural network is given in this paper to further illustrate the performance of the proposed method.
Optimum design of the inlet port profile of a ramjet extended range projectile
Authors: Wang X , Li T
Published: July 2020

The air-inlet is one of the important components of the stamped extended range engine. Its performance directly affects the thrust of the ramjet engine, which in turn affects the range of the projectile. Because the stamped extended range projectile has the characteristics of simple structure, light weight and small volume, the inlet profile of the stamped extended range projectile is generally unadjustable, and the air-inlet surface quality directly determines the performance of the air-inlet. And the resistance characteristics of the shells. Since the air-inlet is associated with the curved portion of the projectile, the curved portion is one of the main sources of resistance to the projectile, so it is necessary to optimize the design of the air-inlet profile. Firstly, based on the CFD flow field simulation, the optimal design method of the air-inlet profile is studied. The parametric modeling, flow field simulation and optimization strategy of the air-inlet are integrated on the platform to realize automatic optimization. The optimization of the nozzle is optimized by this optimized design method, which proves its feasibility. Then, the single-objective optimization and multi-objective optimization of the air-inlet profile are carried out, and the geometric model is established to more accurately describe the flow field characteristics and obtain a more accurate air-inlet profile. Finally, a supersonic wind tunnel test was carried out on the optimized air-inlet, and the wall static pressure and the total outlet pressure of the windward side and the leeward side were measured and compared with the simulated Mach number of 2.5 and 2.0. Comparative Results. The two are basically the same, indicating that the numerical simulation results can basically reflect the pressure change and the change of the total pressure in the air-inlet. Therefore, the reliability of simulation-based optimization results is high.
Simulation study on the jet formation and penetration capability of hypervelocity double-layer liner shaped charges
Authors: Xie J W , Wang H F , Zheng Y F , Geng B Q , Ge Ch
Published: July 2020

The jet formation and penetration capability of hypervelocity double-layer liner shaped charges (HDLLSCs) against rolled homogeneous armor (RHA) targets are investigated by numerical simulation. The HDLLSCs with different cone angle and relative position of disc are simulated to investigate the influence of these parameters on penetration capability and compare with a traditional conical shaped charge (CSC). The simulation results show that, the tip velocity of the jet formed by HDLLSCs with a tantalum disc is lager by 6.8% compared with that formed by the CSCs. The three stages of jet formation for HDLLSC including converge, formation, and secondary impact are revealed and discussed. The penetration capability of HDLLSCs is influenced by the coupled effect of cone angle and relative position of disc, a larger relative position of disc is more suitable for a large cone angle. In addition, the standoff also has a significant effect on the penetration depth of HDLLSCs, the penetration depth increases from 3.31 charge diameter (CD) to 6.52 CD with the standoff increasing from 1.5 CD to 4.0 CD. Moreover, the penetration depth of the jet formed by HDLLSCs is larger by 18.5% compared with that formed by the CSCs at the standoff of 4.0 CD.
Simulation analysis of residual stress of autofrettaged barrel under multi-field coupling loads
Authors: Gao X K , He Q , Liu P K , Shao X J , Wang Z S
Published: July 2020

High-pressure guns repeatedly withstand transient high pressures and high temperatures, which have a great influence on the residual stress of the barrel. In order to study the stress distribution of autofrettaged barrel under multi-field coupling during launch, the mechanical autofrettage gun barrel and finishing process of the barrel was simulated by ANSYS finite element software, in which the finite element model considering the initial residual stress of the autofrettaged barrel was established, and the dynamic and static continuous process simulation of the barrel was carried out. On the basis of obtaining the residual stress distribution, an analytical model under the coupling of transient pressure field and temperature field is established. The APDL language programming is used to calculate the time and space distribution of the stress of the key parts of the barrel. A phenomenon is found that the equivalent stress on the outer surface of the barrel increases sharply with the increase of the pressure, and then rises to the highest point with the temperature of the barrel. After the fire process, the equivalent stress slowly recovers with the decrease of the temperature. The law of external surface stress rise in the fire period is a step process. It provides a theoretical basis for studying the residual stress release law the safety design of barrel.
Finite element modeling of bullet-barrel interaction and mechanism analysis of swing phenomenon of bullet
Authors: Liu H Sh , Xu Ch
Published: July 2020

The process of bullet-barrel interaction refers to the following physical process: after the gun is fired, the bullet moves forward under the push of powder gas, interacts with the barrel by extrusion, friction, contact and collision, and finally leaves the barrel. The swing phenomenon of bullet, which has a great influence on the shooting accuracy, is formed in this process. In order to study the formation of swing phenomenon and effect of barrel structure on swing, a finite element simulation model for the interaction process of a sniper rifle is established and calculated in this paper. The movement and stress distribution of bullet and barrel in bullet-barrel interaction process are obtained by simulation calculation, the swing of the bullet under different bore throat taper and rifle type is compared, and the intuitive process of the swing phenomenon of the bullet is obtained. Based on the calculation results, the following conclusions are obtained: Firstly, the dynamic process of bullet swing formation and amplification is obtained. In pre-shooting stage and extrusion stage, because of eccentricity of structure and other reasons, the bullet’s axis deviates in the process of embedding to form initial disturbance, called formation stage. In post-extrusion stage, the initial disturbance is continuously amplified due to the combined action of bullet structure, contact between bullet and barrel, and the pressure of powder gas, finally, the swing phenomenon of bullet is formed, called the amplification stage. Secondly, the effects of bore throat angle and rifle type on bullet swing are obtained.
Numerical study on the damage behavior of concrete target influenced by penetration velocity and target properties
Authors: Zheng Z J , Ma T B , Xu X Zh
Published: July 2020

The influence of initial penetration velocity and target properties on the damage behavior of concrete target by kinetic energy (KE) projectiles are studied numerically. Numerical models of penetration at different velocities were established, the failure of concrete and the law of the impact at different initial velocities ranging from 950 m/s to 1500 m/s on the damage behavior of concrete target is obtained. Damage process of concrete target slabs with different strengths and thicknesses under various impact load was carried out and the relationships between the damage behavior and the target strength ranging from 35 MPa to 95 MPa and the thickness ranging from 1 m to 2 m were obtained. Combination with the experiment results demonstrates that, the descent rate of the initial velocities increase as the initial velocities were improved. The higher the strength of the target, the less the residual velocity decrease caused by increasing the strength of the target. Under the condition of the same thickness increase amplitude, higher totally thickness of the targets results in greater penetration resistance. Furthermore, the overload peak value and the oscillation period of the impact load are positively related to the initial velocity and target thickness. With the increase of penetration depth, the impact load presents a first dramatic increase, then gradual decrease trend with obvious oscillations.
Research on dynamic response of pbo fiber-reinforced composite under high-speed penetration
Authors: Wang R H , Li F Q , Wang X C , Xu J L , Li S H , Chen Y W , Wang D Y
Published: July 2020

The damage mode and failure mechanism of the PBO composite are studied of the penetrating speed from 900 m/s to 1900 m/s, based on the dynamic response of the PBO fiber-reinforced composite target under high-speed penetration. Firstly, the mechanical properties of the projectile and the target material under high strain rate were characterized, and then the penetration of high-speed projectile into target is simulated. Finally, the penetration test is verified. The results show that the dynamic response mechanism of PBO composite target under high-speed penetration varies significantly with the penetrating speed.
The control algorithm of a programmable tandem detonator
Authors: Kuczerski T , Gibalski D
Published: July 2020

The article describes the results of laboratory tests of the algorithm of control of programmable detonators designed for tandem systems. Control elements were made on the basis of microcontrollers using RISC architecture. The detonator has a system to quickly excite the precursor charge and can be programmed at any time to delay the detonation of the main charge. The lack of delay in excitation of the precursor charge was realized using a comparator. The article presents the results of preliminary laboratory tests of the control algorithm of the executed system. The flexibility of the solution to program any delay time for the excitation of the main load provides a wide range of practical applications.
Reactive Molecular Dynamics Simulation of FTDO Explosive
Authors: Gonçalves R.F.B. , Rocco Bruno T. , Rocco Leopoldo , Rocco J.A.F.F.
Published: July 2020

Predicting explosion parameters is an important step when planning for blast tests or the design of blast resistant buildings and of explosive materials and formulations. This paper presents reactive molecular dynamics simulations of furazanotetrazinedioxide (FTDO) explosive, a new and highly energetic material, calculated with the software LAMMPS with ReaxFF force field. The decomposition steps and chemical mechanism of the material decomposition was elucidated and the Arrhenius parameters of the global decomposition reaction was calculated based on a first order approach with six different isothermal simulations sets. Results present an original mechanism for the detonation/decomposition and an activation energy and frequency factor with high linear determination coefficient. These results are the first ones published for this material and present a good comparison for future experiments.
A stochastic vulnerability analysis method for armored vehicles with active protection systems (APS)
Authors: Feng B , Liang X , Du W G , Qiu C L , Hou R S
Published: July 2020

A stochastic vulnerability analysis method for armored vehicles with APS was proposed. A two-processes threat-target interaction, including an interception process and a damage process, replaced the one-process of threat-target interaction in the traditional vulnerability method. Depending on the vulnerability results of the incoming threat, various residues-after-interception because of detection or interception failure, deflection, explosion and/or decomposition of the threat and collateral damage was generated and treated as input in the damage process. After randomization of the interception point, the residual penetrator deflection, warhead performance, behind armor debris, and component vulnerability characterization, a stochastic vulnerability analysis was performed. The stochastic model could provide damage states of all the critical components of interest, more practical and informative compared to the expected model.
Numerical simulation of 3D barrel system based on thermal-structural coupling under continuous firing
Authors: Gu Z C , Lu H T , Wang S , Yan W M , Xu C
Published: July 2020

In order to study the laws of temperature field and deformation field of the 5.56mm rifle under continuous firing, the barrel system was taken as the research object, the transient temperature field and the deformation field of the 3-D barrel system under continuous firing of 150 rounds was calculated by using thermal-structural coupling method based on ANSYS. The temperature of multiple positions of the combat gun that partially removed the lower handguard was measured by the thermal imager. The difference between the test results and the simulation results was kept below 20%. The results of simulation and experiment showed: (1) The peripheral parts of the barrel have important influence on the temperature field and deformation field of the barrel system, and it is not negligible for the study of the thermal effects of combat gun under continuous firing. (2) The temperature of the inner wall increases with the number of projectiles under continuous firing, and the chromium layer has a significant effect of reducing thermal pulse. (3) Because the barrel is heated more unevenly, it will increase the inner diameter of the barrel and offset the axis. In a word, studying and analyzing the laws of temperature field and deformation field of the rifle can lay the foundation of the thermal management theory of firearms.
Numerical simulation of high-strength concrete under uniaxial/triaxial compression based on meso-scale model
Authors: Zhang X Y , Wu H J , Li J Z , Pi A G , Huang F L
Published: July 2020

According to the meso-scale characteristics and structural composition of concrete, a three-dimensional finite element mesoscopic model is established based on the random aggregate generation method and the background grid projection method. Based on the improved Ottosen yield conditions, the stress-strain curves and damage parameter data of concrete are calculated, and the CDP model is applied to carry out numerical simulation under static uniaxial and triaxial compression conditions. The results show that the stress-strain curve obtained from the numerical simulation is basically consistent with the experiment, and the crack development along the ITZ can be observed in the meso-scale model, which is consistent with the experimental details. It is proved that the modeling method and parameter calculation method in this paper is accuracy and have good applicability.
Tracking of small infrared targets based on convolutional neural network
Authors: Fan Qiang , Sun Gangbo , Zou Erbo
Published: July 2020

As an important application of computer vision, visual tracking has been studied more and more. However, there are still many problems to be solved for infrared target detection, especially for weak infrared target detection and tracking. In addition, convolutional neural networks are widely used in visual applications such as target detection, recognition, and tracking. Therefore, in this paper, an infrared weak target detection and tracking method is designed. Based on the criteria of visual saliency, the real target can estimate by calculating the Euclidean distance between the target and its neighbours. The detected position of the target is sent to a fully convolutional siamese network DeepCF for tracking. As we know, the factors such as lighting changes, scale changes and occlusion cause the tracking failure. Therefore, a tracking confidence T is proposed to judge whether the target is lost. The motion trajectory of the target is continuously estimated if it is lost. The experimental results show that the above method can effectively detect and track infrared weak targets.
A two-stage stabilizing device of multi-degree gimbal based on flexible structure
Authors: Qi Y , Ji M , Wang H L , Xu Q Q , Wang G
Published: July 2020

This paper presents a new type of flexible structure of the gimbal device, the device is composed of multiple flexible supporting structure and cross butterfly voice coil motor, which can realize multi degree of freedom movement, compared with the traditional two-axis four-frame structure, has the advantage of high precision, no friction and compact bodies, and can improve the whole stability of stabilization system precision. The modal simulation of the whole flexible support gimbal is carried out by using ANSYS software, and the results show that the gimbal meets the performance requirements of the stabilized aiming system and can realize multi-degree-of-freedom movement. Finally, through the simulation comparison between the FSM structure and the stabilized aiming system of the universal frame device, the result show that the stability accuracy of the system after FSM compensation is 10urad, while the accuracy error of the flexible structure gimbal is not greater than 5urad, that is, the stability accuracy of the device can be improved. Introduction.
Numerical multi-loop integration on heterogeneous many-core processors
Authors: de Doncker E , Yuasa F , Almulihi A , Nakasato N , Daisaka H , Ishikawa T
Published: July 2020

We report on multi-loop integral computations executed on a PEZY/Exascaler large-scale (immersion cooling) computing system. The programming model requires a host program written in C++ with a PZCL (OpenCL-like) kernel. However the kernel can be generated by the Goose compiler interface, which allows parallelizing program loops according to compiler directives. As an advantage, the executable derived from a program instrumented with Goose pragmas can be run on multiple devices and multiple nodes without changes to the program. We use lattice rules and lattice copy (composite) rules on PEZY to approximate integrals for multi-loop self-energy diagrams with and without masses. GPU results are also given and the performnce on the different architectures is compared.
In situ analysis and visualization of massively parallel simulations of transitional and turbulent flows
Authors: Cadiou A. , Buffat M. , Pera C. , Di Pierro B. , Alizard F. , Le Penven L.
Published: July 2020

The increase of computational resources with the generalization of massively parallel supercomputers benefits to various fields of physics among which turbulence and fluid mechanics, making it possible to increase time and space accuracy and gain further knowledge in fundamental mechanisms. Parametric studies, high fidelity statistics, high resolutions, can be realized. However, this access poses many problems in terms of data management, analysis and visualization. Traditional workflow, consisting of writing raw data on disks and performing post-processing to extract physical quantities of interest, considerably slows down the analysis, if not becomes impossible, because of data transfer, storage and re-accessibility issues. This is particularly difficult when it comes to visualization. Usage has to be revisited to maintain consistency with the accuracy of the computation step and in this context, in situ processing is a promising approach. We developed an in situ analysis and visualization strategy with an hybrid method for transitional and turbulent flow analysis with a pseudo-spectral solver. It is shown to have a low impact on computational time with a reasonable increase of resource usage, while enriching data exploration. Large time sequences have been analyzed. This could not have been achieved with the traditional workflow. Moreover, computational steering has been performed with real-time adjustment of the simulations, thereby getting closer to a numerical experiment process.
New Features in FeynArts & Friends, and how they got used in FeynHiggs
Authors: Hahn T.
Published: July 2020

This note gives an update on recent developments in FeynArts, FormCalc, and LoopTools, and shows how the new features were used in making the latest version of FeynHiggs.
QED and electroweak radiative corrections to polarized Bhabha scattering
Authors: Arbuzov A B , Bondarenko S G , Dydyshka Ya V , Kalinovskaya L V , Rumyantsev L A , Sadykov R R
Published: July 2020

Complete one-loop electroweak radiative corrections to polarized Bhabha scattering are presented. Numerical results are shown for the conditions of future circular and linear electron-positron colliders with polarized beams. A new Monte Carlo event generator for simulation of Bhabha scattering is created. Higher order QED collinear radiation factors are evaluated in the next-to-leading logarithmic approximation.
Further developments of FORM
Authors: Ueda T , Kaneko T , Ruijl B , Vermaseren J A M
Published: July 2020

Form is a symbolic manipulation system, which is especially advantageous for handling gigantic expressions with many small terms, as often occurs in real problems in perturbative quantum field theory. In this work we describe some main features of FORM, such as the preprocessor and $-variables with emphasizing on benefit of metaprogramming, and introduce a new feature: a topology generator.
Ntuples and compact matrix element representations
Authors: Maître Daniel
Published: July 2020

In this contribution I will discuss the practicalities of storing events from a NNLO calculation on disk with the view of “replaying” the simulation for a diferent analysis and under diferent conditions, such as a diferent PDF ft or a diferent scale setting. I also present a way to store a compact representation of the matrix elements for low multiplicity processes.
The Game of Triangles
Authors: Preti Michelangelo
Published: July 2020

We present STR (Star-Triangle Relations), a Mathematica package designed to solve Feynman integrals by means of the method of uniqueness in any Euclidean spacetime dimension. We provide a set of tools to draw Feynman diagrams and interact with them only by the use of the mouse. Throughout the use of a graphic interface, the package should be easily accessible to users with little or no previous experience on diagrams computation.
Towards an efficient method to compute two-loop scalar amplitudes
Authors: Guillet J.Ph. , Pilon E. , Shimizu Y. , Zidi M. S.
Published: July 2020

We report on an ongoing work initiated by Prof. Shimizu, proposing a method to numerically compute two-loop scalar integrals as sums of two-dimensional integrals of generalised one-loop N-point functions analytically computed and integrated over some simple weight functions. The analytic computation of the generalised one-loop N-point functions in a systematic way motivates a novel approach sketched in this talk.
Data-driven Low-energy Generic Generator for CMD-3
Authors: Korobov A A , Eidelman S I
Published: July 2020

A Monte Carlo generator to simulate events of single-photon annihilation to hadrons at center-of-mass energies below 2 GeV is described. The generator is based on existing data on cross sections of various exclusive channels of e+e− annihilation obtained in scan and ISR experiments. It is extensively used in the software packages for analysis of experiments at the Novosibirsk e+e− colliders VEPP-2000 and VEPP-4M aimed at high-precision measurements of hadronic cross sections with different applications, e.g. to calculations of the hadronic vacuum polarization for the muon anomalous magnetic moment.
Decoding the nature of Dark Matter at current and future experiments
Authors: Belyaev Alexander
Published: July 2020

Decoding the nature of Dark Matter (DM) as a crucial part of Beyond-the-Standard-Model (BSM) theory is one of the most important problems of modern particle physics. DM potentially provides unique signatures at collider and non-collider experiments. These signatures are quite generic, however their details could allow us to delineate various BSM models and the properties of DM. While there are many comprehensive studies of the phenomenology of various appealing BSM models, exhibiting “top-bottom” approach, there is no clear strategy for the reverse task of identifying the underlying theory from the new signatures. To solve this problem one should consider the comprehensive set of signatures, database of models and use modern methods, including machine learning and artificial intelligence, to decode the underlying theory from potential signals of new physics we are expecting from the coming experimental data. One of the tools which could be helpful to solve the problem is High Energy Physics Model Database (HEPMDB) which was created to make a step forward towards solving this problem. It is aimed to facilitate connection between HEP theory and experiment, to store, validate and explore BSM models and to collect their signatures. DM decoding is based on the unique complementarity of Large Hadron Collider (LHC) potential as well as on the potential DM direct and indirect detection experiments to probe DM. The combination of our knowledge on this complementarity, modern analysis methods, comprehensive database of BSM models and their signatures is the key point of decoding the nature of DM and the whole underlying theory of Nature.
Effective LHC measurements with matrix elements and machine learning
Authors: Brehmer J. , Cranmer K. , Espejo I. , Kling F. , Louppe G. , Pavez J.
Published: July 2020

One major challenge for the legacy measurements at the LHC is that the likelihood function is not tractable when the collected data is high-dimensional and the detector response has to be modeled. We review how different analysis strategies solve this issue, including the traditional histogram approach used in most particle physics analyses, the Matrix Element Method, Optimal Observables, and modern techniques based on neural density estimation. We then discuss powerful new inference methods that use a combination of matrix element information and machine learning to accurately estimate the likelihood function. The MadMiner package automates all necessary data-processing steps. In first studies we find that these new techniques have the potential to substantially improve the sensitivity of the LHC legacy measurements.
Performance evaluation of distributed file systems for the phase-II upgrade of the ATLAS experiment at CERN
Authors: Abed Abud Adam , Le Goff Fabrice , Avolio Giuseppe
Published: July 2020

Over the next few years, the LHC will prepare for the upcoming High-Luminosity upgrade in which it is expected to deliver ten times more pp collisions. This will create a harsher radiation environment and higher detector occupancy. In this context, the ATLAS experiment, one of the general purpose experiments at the LHC, plans substantial upgrades to the detectors and to the trigger system in order to efficiently select events. Similarly, the Data Acquisition System (DAQ) will have to redesign the data-flow architecture to accommodate for the large increase in event and data rates. The Phase-II DAQ design involves a large distributed storage system that buffers data read out from the detector, while a computing farm (Event Filter) analyzes and selects the most interesting events. This system will have to handle 5.2 TB/s of input data for an event rate of 1 MHz and provide access to 3 TB/s of these data to the filtering farm. A possible implementation for such a design is based on distributed file systems (DFS) which are becoming ubiquitous among the big data industry. Features of DFS such as replication strategies and smart placement policies match the distributed nature and the requirements of the new data-flow system. This paper presents an up-to-date performance evaluation of some of the DFS currently available: GlusterFS, HadoopFS and CephFS. After characterization of the future data-flow systems workload, we report on small-scale raw performance and scalability studies. Finally, we conclude on the suitability of such systems to the tight constraints expected for the ATLAS experiment in phase-II and, in general, what benefits the HEP community can take from these storage technologies.
Simulating Diverse HEP Workflows on Heterogeneous Architectures
Authors: Leggett Charles , Shapoval Illya , Clemencic Marco , Jones Christopher
Published: July 2020

We evaluate key patterns and estimate throughput bounds of simulated transformation of conventional high energy physics (HEP) data processing workflows to heterogeneous equivalents. The simulation parameter space includes the number of offloaded tasks, CPU/accelerator ratios of intra-task computations, offload latencies, and run time efficiency of offloaded computations. The simulation is performed for a diverse set of state-of-the-art event reconstruction scenarios from ATLAS, LHCb and CMS - the frontier HEP experiments of the Large Hadron Collider project.
JANA2: Multithreaded Event Reconstruction
Authors: Lawrence D , Boehnlein A , Brei N , Romanov D
Published: July 2020

JANA2 is a multi-threaded event reconstruction framework being developed for Experimental Nuclear Physics. It is an LDRD1 funded project that will be the successor of the original JANA framework. JANA2 is a near complete rewrite emphasizing C++ language features that have only become available since the introduction of the C++11 standard. Features such as shared pointers, language native threading, and atomics are employed. This paper outlines the status of the project.