bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical simulation of dynamic response of underwater supercavitating projectile structure based on after-effect enhancement of kinetic penetration
Authors: Li X , Yan P , Tan B , Zhao Y L , Liang W G
Published: July 2020

Aiming at the underwater supercavitating projectile, a damage mode of enhanced effect after kinetic penetration is proposed. The structure of energetic projectile with prefabricated breaking groove is designed, which can not only ensure the projectile strength in underwater motion, but also release the filling agent to the interior of the target through the projectile fracture when hitting the target. Based on ANSYS/LS-DYNA finite element analysis software, the equivalent model of supercavitating energetic projectile penetrating low-carbon steel shell of mine in three-phase domain is established. The dynamic response of the projectile in the stage of underwater motion and penetration is obtained by analyzing the force of the key parts of projectile and observing the deformation of the projectile structure. By changing the initial velocity and landing angle of the projectile, analyzing the law of velocity variation and penetration depth of the projectile, observing the deformation of the projectile structure and the phenomenon of the energetic agent disperation when penetrating the steel plate, the quantitative conclusion of the damage effect of the energetic projectile on the typical mine target under different working conditions is obtained. The research results have reference value for the structural design and power evaluation of underwater supercavitating energetic projectile.
Study on strain rate dependence and energy absorption characteristics of two aluminum alloys 7A62 and 7085
Authors: Wan M M , Wang Y L , Wu H L , Wang S L , Li B W , Mu X M
Published: July 2020

The dynamic compression properties of two aluminum alloys 7A62 and 7085 were tested using Split Hopkinson Pressure Bar (SHPB ) technique. The effects of strain rate on yield stress and dynamic energy absorption characteristics of the two materials were analyzed. The critical strain rate and the maximum energy absorbed before shear failure occurred of the two materials were given. The results showed that both the two materials show a strong strain rate dependence effect, and the yield stress increased with increasing strain rate. The aluminum alloy 7085 has a lower yield stress than 7A62 under the same strain rate level. But it has a better energy absorption characteristic than 7A62 for its good plasticity.
Dynamic response of fiber-composite-reinforced shell structure subjected to internal blast loading
Authors: Gan Y D , Wei D , Zhang Q M , Su J J , Long R R , Chen P W , Liang H Z
Published: July 2020

In this study, we report the analysis of a dynamic response process of a fiber-composite-reinforced shell when subjected to internal blast loading of different TNT equivalent by using a three-dimensional digital image correlation method. And it was compared with the dynamic response of the metal shell with the same TNT equivalent and the same surface density. We received the relationship between dynamic deformations and the sizes of the two shells under different TNT equivalence. Through comparison of the results, it was shown that the response process of the fiber-composite-reinforced shell was much more complex than that of the metal shell. Our experimental results suggest that the shock wave intensity, the material mechanical properties and the structure symmetry had important influences at different stages of the structural dynamic response. Fiber composites with high strength restricted the structural deformation extent and deformation rate. In addition, the interaction between fiber composite and metal liner reduced the probability of structural damage caused by the energy concentration. This work provides important insights for the design of cylindrical explosion vessels.
Microstructure and mechanical properties of AI/Fe micro-laminated composites fabricated by ultrasonic consolidation
Authors: Wang Y , Hou F M , Yang Q , Fan Z Y , Pan H Y , Xu H
Published: July 2020

Ultrasonic consolidation technology is a new method for preparing high-performance laminate composite materials. This rapid consolidation additive manufacturing technology provides a new idea for the integration of complementary functional laminated composite structures. It has great potential for preparation of new generation of complex laminated composite parts, broadening the application field of laminated composite material, and means an advanced 3D additive manufacturing technology for materials and structures. In this paper, it is aimed at Al/carbon steel and Al/Fe laminated composites systems with low cost and multilayer structures, Al/carbon steel and Al/Fe laminated composite samples were consolidated by ultrasonic consolidation process. And the Al/carbon steel and Al/Fe interfacial bonding were studied by SEM and EDS. The hardness and tensile properties of laminated composites were tested by mechanical properties together with the fracture morphology of each interface was studied.
Improving dimensional and surface quality of additive manufactured parts
Authors: Bruni C , Gianangeli C , Mancia T , Greco L , Pieralisi M
Published: July 2020

In modern manufacturing of polymer components the injection moulding represents the conventional way to get the desired shape respecting dimensional and surface requirements. But, such process plan requires the design of the tools and that of whole manufacturing process. A different choice could be done when the production consists of small batches or a single unit. In this case it is useful to realize the workpiece without tools taking into consideration the additive manufacturing technique. The limit of such flexible manufacturing technology is represented sometimes, in particular in working polymers such as ABS, by the difficulty to respect dimensional and surface requirements. The research activity to be presented involved the realization of cubic geometries in ABS by FDM (Fused Deposition Modeling). The staircase, the waviness and roughness of the surfaces were evaluated and quantified. The slight machining phase performed by front milling considered in the process plan allowed to reduce the staircase effect up to about zero and to reduce the waviness of about some decimals of millimeter to some hundredth of millimeter. The surface roughness was also improved. The methodology and the details are reported.
Study on microstructure control and performance optimization of ZCuPb20Sn5 alloy by rare earth la
Authors: Ren X Y , Zhang G W , Hong X , Sun F E
Published: July 2020

ZCuPb20Sn5 alloy is a cast lead-tin bronze alloy. Due to its high lead content, it has excellent comprehensive properties such as friction reduction and wear resistance, high fatigue strength, good thermal conductivity, and good wear resistance. It is widely used in automobiles, Aerospace industry and other fields. Therefore, this article selects ZCuPb20Sn5 alloy as the research object. By adding rare earth La to ZCuPb20Sn5 alloy solution, the metallographic structure and mechanical properties are observed, and the effect of rare earth La on the microstructure and properties of ZCuPb20Sn5 alloy material is analyzed. The results show that with the increase of La content, the tensile strength, elongation and hardness of lead-tin bronze alloys all increase first and then decrease. Without the addition of rare earth lanthanum, the tensile strength of lead-tin bronze can reach about 241.5 MPa. Adding different amounts of rare earth to the lead-tin bronze alloy can improve the tensile strength and elongation of the alloy. When 0.04 wt.% rare earth lanthanum is added, The strength and elongation reached the maximum. After several experiments, the tensile strength remained at about 267.1, the elongation remained at about 15.13%, the tensile strength increased by about 25.6 MPa, and the hardness remained at about 80 HB, with little increase.
The pre-hot dipping effects on the bimetal casting of nitriding steel sleeve into the Al-Si matrix
Authors: Xu H , Guo B X , Fan Z Y , Mao H K , Wang Y
Published: July 2020

Steel-aluminum composite material combine the excellent mechanical properties of steel such as high strength and good wear resistance with the advantages of lightweight aluminum for widely using in automobile engine block, gearbox and other car body structures. In this paper, a new process is used to cast the alloy steel sleeve into Al-Si alloy matrix for preparing aluminum engine block with steel cylinder liner. The process consists of three parts: the surface pre-treatment of steel, the hot-dipping melt and solid-liquid casting of steel with aluminum. Generally, the hot dipping melt should have lower melting point than the melting point of aluminum alloy, good temperature oxidation resistance and amount of solid solubility both with steel and aluminum. Giving consideration of such condition and cost, Zn´ Al and its alloys are used in present paper for learning the effect of hot dip coating melts on the interface properties of steel/aluminum at different times. After hot dipping, a coating formed on the surface of the steel bushing, which improves its wettability in the aluminum melt and the metallurgical bonding effect of the steel-aluminum interface. The microstructure, phase composition, growth kinetics and hardness distribution of the interface were analyzed by metallographic microscopy, scanning electron microscopy with EDS. The results show that the metallurgical bonding interface of steel/aluminum bimetal casting can be obtained by hot dipping. Hard-brittle diffusion layer produced by dipping pure Al is thicker than that produced by ZL101. Dipping pure zinc produces a dense intermetallic layer of 3-5 um and a large amount of dispersed phase of Al3FeZnx, and the bonding performance of such interface is better than the other two. The interface hardness of steel-aluminum bimetal casting obtained by hot dipping pure Al melt, ZL101 melt and pure Zn melt can reach 563.5HV, 528.3HV and 632.3HV, respectively.
Adaptive bionic joint base on the flexibility feature of ostrich intertarsal joint
Authors: Zhang R , Cao Q Q , Ling L , Kong L X , Wang C , Su B , Wen L G , Li J Q
Published: July 2020

The joints of traditional foot robots are generally designed as power-driven articulated rotary motion, but this design has some problems such as poor flexibility and adaptability. To optimize joints, this paper selected the African ostrich intertarsal joint which could move at high speed in complex terrain as a biomimetic prototype. Based on the motion acquisition and reverse engineering three-dimensional reconstruction of the intertarsal joint, a rope-driven spherical sub-bionic joint was designed. The angle curves of the bionic joints under different ground conditions were obtained through the hard ground and the motion tests of three different softness sands (medium with different particle sizes). Results showed that the proportion of the vacant period was 35%, 49%, 62% and 63% when the bionic joint moved on the hard ground and three soft grounds (the particle size particles are arranged from large to small),. The range of variation gradually becomes larger, similar to the variation trend of the intertarsal joint during ostrich locomotion. The bionic joint was able to absorb joint impact through the relative slippage of the joint surface and expansion/contraction of the rope, and maintain flexibility when passing through different degrees of softness.
Study on application of open source intelligence from social media in the military
Authors: Ju Y , Li Q , Liu H Y , Cui X M , Wang Zh H
Published: July 2020

With the gradual popularization of information technology and network technology, various types of open source information, especially social media information, have shown an explosive growth trend. Social media intelligence not only possesses ideological and value-level values, but also directly serves military defense. It will help stimulate open source intelligence to play a huge role in combat operations that combining communications and psychological knowledge to explore and exploit frontier technologies in artificial intelligence, such as machine learning and data mining, and conducting research on social media big data collection, analysis, mining, and prediction technologies. This paper focuses on the preliminary analysis of the application of open source information such as social media in the field of military intelligence.
Revelation of catalytic reduction process affecting the morphology and properties of CNTs/carbon fabrics and their composites
Authors: Lu R J , Zhong T , Wu H L , Miao C , Bai L H , Yuan W , Wang C G
Published: July 2020

Carbon nanotubes/carbon fabrics and their reinforced resin matrix composites were manufactured by chemical vapor deposition and molding method, respectively. Different catalytic reduction processes with different catalyst types and reduction temperatures had different effects on their morphology and properties. It was found by a series of characterization methods that the catalytic activity of the bimetallic catalyst was higher than that of the single metal, and the surface uniformity of CNTs catalyzed by Fe-Co was the best. When the reduction temperature reached the growth temperature, the uniformity of CNTs and the interlaminar shear strength of composites increased obviously. The influence mechanism of these parameters was discussed in depth, which provided a fundamental engineering basis for understanding of catalytic reduction process, optimizing of CNTs growth process and the application of high-performance composite materials.
Structural designation and mechanical properties of TiNi/Ti2Ni laminated composites
Authors: Jia C , Xiong Z P , Liu Z , Cheng XW
Published: July 2020

TiNi/Ti2Ni laminated composites were fabricated using hot isostatic pressing (HIP) furnace together with structural designation by the control of Ti and Ni foil thicknesses. During HIP processing, Ti reacts with Ni, leading to the formation of softer TiNi and harder Ti2Ni. Through adjusting the thickness ratio of Ti and Ni foils, the ratio of TiNi and Ti2Ni fraction can be controlled. Hard-soft-hard, soft-hard-soft and hard-intermediate-soft laminated composites were designed, where hard layer was made by 50 μm Ti and 20 μm Ni, soft layer was made by 40 μm Ti and 20 μm Ni, and the intermediate structure between hard and soft ones was made by 45 μm Ti and 20 μm Ni. The mechanical properties were characterized using uniaxial tension, uniaxial compression, single edge-notched beam and split-Hopkinson pressure bar. The results show that all three laminated composites have compression strength of 1690 ∼ 1853 MPa and fracture toughness of 27.2 ∼ 37.9 MPa• m1/2 due to the same constituents of TiNi and Ti2Ni. However, the soft-hard-soft structure shows the best response under high strain rate because it was fractured into larger pieces while the other two structures were fractured into smaller pieces together with smaller fracture strain.
Numerical analysis of railgun muzzle flow field with multi-component plasma
Authors: Gao Y , Ni Y J , Li B M
Published: July 2020

The railgun is a new concept launching weapon with high supersonic launching capability. Under the acceleration of Lorentz force produced by the discharge of strong pulse power source, the projectile leaves the muzzle in hypersonic speed. Due to the severe friction of armature in bore and the phenomenon of transition ablation, metal vapor is produced in the interior ballistic process and rush out of muzzle along with armature’s movement. Because of the open structure at both ends of the railgun, the pressure in the bore is much lower than the standard atmosphere, so there exists the phenomenon of muzzle gas backflow. In this paper, the coupled interface method and the multi-component plasma model are used to simulate the movement of metal vapor in the process of projectile moving out of the bore. The pressure boundary conditions and gas composition in the muzzle region of the simulation results are fitted and introduced into the MHD calculation model. The gas backflow phenomenon under the influence of multi-component gas and arc is further simulated. The results show that the muzzle arc improves the energy level of the muzzle flow field and promotes the gas backflow to a certain extent.
Study on the operation mode of repetitive inductive pulsed power supply
Authors: Chen Y , Li H T , An Y Zh , Hu Y Ch , Jiao C , Liang X Y
Published: July 2020

Inductive hybrid pulsed power supplies (PPS) have attracted widespread attention in the field of electromagnetic Launch (EML). In our previous studies, a repetitive inductive PPS circuit topology based on a bridge-type capacitor switching circuit and a high-temperature superconducting pulsed power transformer(HTSPPT) was proposed. By using superconducting inductors, this circuit reduces the power requirements of the primary power supply. However, to prevent the charging current from exceeding the critical current of the superconducting inductors, the circuit must enter the discharging phase immediately when the charging current reaches the designated value, even the discharge time is inappropriate. On the issue, this paper proposes a new operation mode, which is inspired by the trickle charging of accumulators. In this mode, the circuit can keep working in the introduced trickle charging phase until the discharge pulse is required. To study the feasibility of this mode, a preliminary experiment was carried out based on an HTSPPT. The results show that the discharge time can be controlled by instructions and the proposed operation mode is feasible. In addition, the critical parameters and error control methods of the proposed operation mode are also analysed and discussed.
Analysis and optimization of the two-dimensional model of the armature rotation on the electromagnetic railgun
Authors: Liu Xiangrong , Ma Fuqiang , Wei Jiufu , Li Baoming
Published: July 2020

In order to generate enough electromagnetic torque on the armature during the electromagnetic launching process, an asymmetrical structure is adopted in this paper. And a two-dimensional armature model is established for analyzing this asymmetrical structure. Based on this model and the translational equation of the armature, the size parameters of the armature are optimized under the premise of the fixed device parameters of the pulse power supplies and the barrel. The effective length of the armature is between 5mm and 20mm, and the radius of the internal contour for the armature is between 0 and 4mm. The results show that when the above two parameters are 20mm and 4mm respectively, the armature can obtain the largest angular velocity. The maximum value is up to 1087.3rad/s. It is meaningful to guide the armature design of the electromagnetic railgun.
Research on intelligent decision of fire distribution in remote control weapon station
Authors: Wu Y C , Zhang Zh Y , Xiang X F
Published: July 2020

The complex and changeable battlefield environment and personal emotions may affect the decision-making of the battlefield. In order to reduce these effects, make the remote weapon station autonomous, fast, reasonable distribution of firepower, to achieve accurate and effective target strike. In this paper, according to the difference of attacking targets, the threat evaluation models of different targets are established, the evaluation functions of target attributes are set up, and the ranking results are compared with the commander’s subjective decision-making. The evaluation results of the model are consistent with the expert evaluation results. It is proved that the remote control weapon station can overcome the subjective factors and strike the target reasonably when it distributes fire to different attacking targets according to the model, which has high reliability.
Application research on fiber-optic current sensor in large pulse current measurement
Authors: Ye W , Dong Z , Ren R , Liu J , Huang K , Zhang C
Published: July 2020

Rogowski coil is usually used to measure pulse current in directed energy weapon experiments, which is lack of direct and low-frequency components in current measurement, and influenced by interferences like outside electromagnetic field and mechanical vibration. To acquire pulse current data with higher accuracy, a new kind fiber-optic current sensor is proposed to achieve large pulse current measurement, and working principle of the sensor is introduced in this paper. A fiber-optic current sensor is fabricated by cooperative agency, which has measuring range from 0 to 200kA and precision better than 1%. Comparison experiment between the fiber-optic current sensor and Rogowski coil made by PEM from England is tested. The experiment results show that main components of pulse current waves measured by two sensors are similar. Current wave measured by fiber-optic current sensor gets less noise signal than Rogowski coil, and has more details with small current. The fiber-optic current sensor could achieve direct and low-frequency component current measurement, but its max response frequency is 500 kHz. According to the research results, compared to Rogowski coil in pulse current measurement application, the new kind fiber-optic current sensor has better character in direct and low-frequency component current measurement, strong anti-interference ability, high sensitivity and ability to acquire current measurement data with higher accuracy. This sensor would satisfy measurement demands of large pulse current measurement in directed energy weapon better, if it gets better frequency response ability.
Comparative study on longitudinal momentum characteristics of L-type and I-type breech in railgun
Authors: Xu Y T , Li B M
Published: July 2020

The position and magnitude of the longitudinal force during launch are very important to the design of electromagnetic railgun. This problem has become a hot topic of research for a long time. Previous experiments showed that most of the recoil force of the electromagnetic railgun locates at the breech. In order to study the stress distribution and momentum characteristics of the breech during launch. Based on Maxwell’s stress tensor, the momentum conservation equations for electromagnetic railgun were derived. Depending on whether the direction of the source current is perpendicular to the current direction in the rails, the breech is simplified and summarized into I-type and L-type structures. Then, the 3-d models of the two breeches were established and the launch process was simulated by finite element method. Some results such as the current density, magnetic field intensity and electromagnetic stress of the current injector plates and coaxial power connector under both models were obtained. The simulation results show that the longitudinal force on the breech is concentrated on the current injector plates. The longitudinal force on the power connector of L-type breech is much bigger than that of the I-type breech, up to nine times. Besides, different structures of the breech will not affect the launch performance of the railgun.
Research on Anti-seated Device of Certain Electromagnetic Weapon
Authors: Fan T F , Ma J J , Huang K , Huang Q
Published: July 2020

The electromagnetic railgun is a new concept weapon that uses Loren magnetic to accelerate the projectile to super high-sonic speed instantaneously. The initial velocity of the projectile muzzle can reach 2km/s or more in an instant. The projectile launched by the electromagnetic railgun has a high speed and thus has a strong kinetic energy to impact the target. According to the principle of force, when the weapon system pushes the armature, the recoil part will be subjected to a force in the opposite direction, that is, the combined force of the gun. If there is no anti-rear device, the force will generate strong vibration excitation to the launching frame, affecting the shooting intensity of the projectile. In order to reduce the influence of the squat resistance of the electromagnetic weapon on the accuracy of the weapon system, the model of the anti-rear device of the electromagnetic weapon is established. The simulation analysis and experimental verification are carried out. The simulation structure and experimental data are in good agreement.
Feasibility analysis and simulation study of shooting after shortest distance between target and projectiles
Authors: Chang S F , Wang J , Li X J , Fan. Ch X
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.
Impact envelope simulation for kinetic kill missile intercepting short range high speed target
Authors: Chen Kun , Ren Yang , Gong Zheng , Lu Qi
Published: July 2020

For direct impact kinetic kill missile, it not only need high precision guidance technology, but also related to the size, collision position, angle and speed of missile and target. Due to the limitations of the real projectile interception test technology, the cost and the launching technology of ground hypervelocity collision experiment, the simulation modeling and analysis are the main means to carry out the research of direct collision kinetic technology and the evaluation of interception effect. In this paper, aiming at the kinetic energy interception of short range high-speed target under the constraints of collision angle and miss distance, the terminal impact envelope is simulated, and the relative position of missile and target on the collision probability is analyzed.
Reynolds number effects of supercritical airfoil with mini-TED in transonic flow
Authors: Xu X , Liu D W , Chen D H , Cheng K M
Published: July 2020

In order to accurately investigate the Reynolds number influence of supercritical airfoil with miniature trailing-edge devices (mini-TED) under transonic conditions. The supercritical airfoil pressure measurement test of high Reynolds number was conducted in the European transonic wind tunnel. The reliability of the high Reynolds number numerical calculation method was validated by the wind tunnel test results. The calculation results are in good agreement with the wind tunnel test results, indicating that the high Reynolds number calculation accuracy could meets the investigation requirement. The transonic flow of supercritical airfoil with mini-TED in the range of Reynolds number 3×106∼50×106 and Mach number 0.76 was simulated using the validated calculation method. Due to the existence of mini-TED, the Reynolds number influence self-adjustment range of the supercritical airfoil disappeared, while the influence magnitude and sensitivity reduced. At the same time, the supercritical airfoil’s linear influence of Reynolds number effects has been changed, and the Reynolds number prediction method based on pressure distribution is no longer applicable. After considering the influence of Reynolds number, the detailed design of supercritical wing with mini-TED could be conducted to improve its reliability and economy in the application of advanced aircraft.
Finite element analysis of the friction and wear of the barrel bore during the projectile extrusion
Authors: Zou L B , Yu C G , Feng G B , Zhong J L , Liu X F , Liang L
Published: July 2020

The size change of the forcing cone directly affects the ballistic performance of the gun and the life of the gun barrel. In order to study the force law and wear law of the forcing cone during the continuous engraving process of the projectile, which established a refined finite element model of the projectile-barrel interaction. The model contains rifling finite element mesh grid with process chamfer. Based on the established transient coupled thermo-mechanical finite element (FE) model of the projectile-barrel interaction, the effects of the temperature and pressure of the gunpowder gas, the friction coefficient between the rotating band and the forcing cone were comprehensively considered. Combined with the Archard wear model, numerical method are used to obtain the stress law of the forcing cone and the amount of wear due to friction in the continuous engraving process of the projectile. The research content in this article can provide some guidance for predicting the life of the tube.
A simulation method of active protection system defeat probability
Authors: Yang Y , Song H P , Wang P G , Zhang Y N
Published: July 2020

The past thirty years have seen increasingly rapid advances in the field of Active Protection (AP) technics, and it is widely accepted that the AP system will play a marked role in future combat vehicle design, on account of its contribution to increasing vehicles’ viability without the burden of heavy armor. Depends on their concepts, a conventional AP system may consist of various components range from detectors, sensors, controllers, launchers to countermeasures, and what stands out in the AP system design are the inevitable errors derived from each operating session making the engagement results unpredictable, for example the tracking error of sensors, position error of launcher deployment, etc. The modelling method presented in this paper is a useful account of how to evaluate the AP system errors, and estimate the defeat probability of AP system upon the given boundary conditions.
Modeling of structure formation of energy-saturated heterogeneous composite material
Authors: Kryvanos A.K. , Ilyushchanka A.Ph. , Buloychik V.M.
Published: July 2020

One of the approaches to modeling of the structure formation of an energy-saturated heterogeneous composite material (EHCM) by mixing its components represented by liquid and solid phases was considered. To develop a model of the mixing process, one of the heuristic algorithms was used, i.e. the metal annealing method. The model is formalized with the condition of averaging the particle sizes within each of the fractions, as well as the morphology of their surface. As a representative element of the model, an elementary cell is adopted in the form of hexogonally densely packed particles around one introduced into the composition of the composite material (in small amounts, from 5 to 15 %) as a modifier. The voids in the cell are filled with liquid polymer. The developed model is based on the objective function, which assumes obtaining a uniform distribution of components with the required density of their packing and filling the voids with a liquid phase while minimizing the number of mixing iterations. A comparison of the values resulted during modeling with the measured characteristics of mixing on a particular mixer will make it possible to form a matching scale of the modeling results to the operating modes of technological equipment. This will determine the appropriate modes of mixing the components at the stage of development of the technological process of EHCM production.
Quantitative analysis for affecting factors of firing dispersion of tank
Authors: Liu F F , Song M , J Z  , Yu H L , Si Z H , Xu Y F , Cheng Y G , Ding M K , Rui X T
Published: July 2020

To improve the firing dispersion of the tank, the influences of random factors on firing dispersion are analyzed quantitatively. Based on the six-degree-of-freedom rigid-body ballistic equation, considering the influences of processing and assembly errors, initial disturbances and the wind on flight, using the Sobol’ global sensitivity analysis method, the weights of affecting factor are obtained. The analysis results show that, under the current manufacturing and measuring conditions, the initial disturbance of projectile is the premier factor that takes effect on the firing dispersion of the straight shooting weapon (such as a tank) with small elevation angle.
Study of coupling thermal and mechanical effect on submerged nozzle in solid rocket motor
Authors: Gong J L , Xue R , Deng Z
Published: July 2020

The thermo-structural response of submerged nozzles is widely investigated in the design of modern rockets upon thermal loading and aerodynamic pressure. In this paper, by means of commercial finite element software with the subroutine of non-uniform pressure and non-uniform heat transfer coefficients, the simulation was performed to study the thermo-structural response of a submerged nozzle at the pressure 6MPa and stagnation temperature 3200K. By means of fluid software, the steady flow field with hot gas was determined. The aerodynamic parameters and heat coefficients were obtained. It was found that the thermal loading has an important influence on stress of throat insert for the solid rocket motor (SRM). Secondly, the hoop stress increases at first and then decreases with the increase of time for the throat insert. Finally, the ground hot firing test of SRM with submerged nozzle was carried out. The structural integrity of the submerged nozzle is very perfect during SRM operation. The present method is reasonable, which can be applied to study the thermo-structural response of submerged nozzle for SRM.
Numerical simulation of damage effect for runway subjected to explosive loading
Authors: Liang B , Nie Y , Zhou J Q , Bai Y S , Qian L X , Feng G P , Yu C X , Lu Y G
Published: July 2020

In order to study the blast damage effect of kinetic energy warhead. It is concerned with use the hydro code AUTODYN for the simulation of explosive loading interactions to multilayer runway. A study is presented including an investigation of the effect of blasting depth, layer of runway, boundary of target. Comparisons and analysis are made with crater size, crunch area radius, damage area and the peak pressure. Based on this analysis Based on the theoretical analysis and numerical simulation results, Preliminary rule between explosive effect and influence parameter is obtained. The simulated results have reference value for the design of the penetrator and damage evaluation.
Study on precise detecting and controlling technology of lag angle based on image processing
Authors: Kang Z , Li S , Li X , Xiu D , Guo B
Published: July 2020

A precise method of detecting and controlling of lag angle during the optical fiber winding procedure is described in this paper. The system is composed of three modules, image collection, image processing and PC controller. Images of lag angle are collected by an industrial high-speed camera. Binary treatment on lag angle images of the motive optical fiber is done by global threshold method. Image identification of lag angle of the motive optical fiber is realized by Hough transform, thus the digital values of lag angel are obtained. PC outputs controlled variables to modify the winding motion based on detecting results so as to limit the lag angel in a precise range. The research result indicates that application of image collection and identification technology to optical fiber winding can avoid winding flaw effectively such as gap and lamination thus to improve the quality and efficiency of optical fiber winding.
Object detection and tracking algorithms using brain-inspired model and deep neural networks
Authors: Song Y , Zhao YF , Yang X , Zhou Y , Wang F N , Zhang Z S , Guo Z K
Published: July 2020

As the most effective bio-intelligence system, Human Visual System (HVS) has significant advantages in image processing, which helps to solve the problems in infrared target detection and tracking, such as dim small target, complex background, target occlusion and appearance changes, etc. In this paper, several brain-inspired models (including lateral inhibition, receptive field, synchronous burst, visual attention, and cognitive memory) and Deep Neural Networks (DNNs) have been studied, and the corresponding algorithms are proposed, which include: an infrared target detection algorithm based on lateral inhibition and singular value decomposition, an infrared target detection algorithm based on receptive field and lateral inhibition, an infrared moving dim target detection algorithm based on ALI-PCNN, an infrared target detection algorithm based on GCF-SB visual attention model, a kernel correlation filtering target tracking algorithm based on multi-channel memory model, and a robust and efficient discriminative-correlation-filter-based tracking approach based on the Response Map Analysis Network. Our experimental results show that the proposed algorithms are beneficial to achieve accurate infrared target detection and robust tracking under complex conditions.
Monte Carlo phase space integration for initial state radiation
Authors: Redouane-Salah E , Bauer C W
Published: July 2020

Efficient phase space integration is important for some calculations in collider physics. Using the Altarelli-Parisi splitting functions as the underlying probability for a splitting, we developed a phase space calculation for initial state radiation, that relies on Monte Carlo integration.
Trilinear Higgs boson coupling variations for di-Higgs production with full NLO QCD predictions in Powheg
Authors: Heinrich G. , Jones S. , Kerner M. , Luisoni G. , Scyboz L.
Published: July 2020

The couplings of the Higgs boson to other particles are increasingly well measured by the ATLAS and CMS experiments. The Higgs boson trilinear self-coupling however is still largely unconstrained, mainly due to the low cross-section for Higgs boson pair production. We present inclusive and differential results for the NLO QCD corrections to Higgs boson pair production with the full top-quark mass dependence, where the Higgs trilinear coupling is varied to non-SM values. The fixed-order calculation is supplemented by parton showering within the Powheg-BOX-V2 event generator, and both Pythia8 and Herwig7 parton-shower algorithms are implemented in a preliminary study of shower effects.
Multi-threaded checksum computation for ATLAS high-performance storage software
Authors: Le Goff Fabrice , Avolio Giuseppe
Published: July 2020

ATLAS is one of the general purpose experiments observing hadron collisions at the LHC at CERN. Its trigger and data acquisition system (TDAQ) is responsible for selecting and transporting interesting physics events from the detector to permanent storage where the data are used for further processing. The transient storage of ATLAS TDAQ is the last component of the online system in the data flow. It records selected events at several GB/s to non-volatile storage before transfer to offline permanent storage. The transient storage is a distributed system consisting of high-performance direct-attached storage servers accounting for 480 hard drives. A distributed multi-threaded C++ application operates the hardware. The transient storage is also responsible for computing a checksum for the data, which is used to ensure data integrity of the transferred data. Reliability and efficiency of this system are critical for the operations of TDAQ as well. This paper presents the existing multi-threading strategy of the software and how the available hardware resources are used. We then introduce how multi-threaded checksum computation was introduced to increase significantly the maximum throughput of the system. We discuss the key concepts of the implementation with a focus on the importance of overhead minimization. Finally the paper reports on the tests done on the production system to demonstrate the validity of the implementation and measurements of the performance improvement in the view of future LHC and ATLAS upgrades.
Migrating large codebases to C++ Modules
Authors: Takahashi Y , Shadura O , Vassilev V
Published: July 2020

ROOT has several features which interact with libraries and require implicit header inclusion. This can be triggered by reading or writing data on disk, or user actions at the prompt. Often, the headers are immutable, and reparsing is redundant. C++ Modules are designed to minimize the reparsing of the same header content by providing an efficient on-disk representation of C++ Code. ROOT has released a C++ Modules-aware technology preview, which intends to become the default for the ROOT 6.20 release.

In this paper, we will summarize our experience with migrating C++ Modules to LHC experiment’s software codebases, particularly for CMS software (CMSSW). We outline the challenges with adopting C++ Modules for CMSSW, including the integration of C++ Modules support in the CMS build system and we will evaluate the CMSSW performance benefits.
HEP Analyses on Dynamically Allocated Opportunistic Computing Resources
Authors: Schnepf M J , von Cube R F , Heidecker C , Fischer M , Giffels M , Kuehn E , Heiss A , Petzold A , Quast G , Sauter M
Published: July 2020

The current experiments in high energy physics (HEP) have a huge data rate. To convert the measured data, an enormous number of computing resources is needed and will further increase with upgraded and newer experiments. To fulfill the ever-growing demand the allocation of additional, potentially only temporary available non-HEP dedicated resources is important. These so-called opportunistic resources cannot only be used for analyses in general but are also well-suited to cover the typical unpredictable peak demands for computing resources. For both use cases, the temporary availability of the opportunistic resources requires a dynamic allocation, integration, and management, while their heterogeneity requires optimization to maintain high resource utilization by allocating best matching resources. To find the best matching resources which should be allocated is challenging due to the unpredictable submission behavior as well as an ever-changing mixture of workflows with different requirements.

Instead of predicting the best matching resource, we base our decisions on the utilization of resources. For this reason, we are developing the resource manager TARDIS (Transparent Adaptive Resource Dynamic Integration System) which manages and dynamically requests or releases resources. The decision of how many resources TARDIS has to request is implemented in COBalD (COBald - The Opportunistic Balancing Daemon) to ensure further allocation of well-used resources while reducing the amount of insufficiently used ones. TARDIS allocates and manages resources from various resource providers such as HPC centers or commercial and public clouds while ensuring a dynamic allocation and efficient utilization of these heterogeneous opportunistic resources.

Furthermore, TARDIS integrates the allocated opportunistic resources into one overlay batch system which provides a single point of entry for all users. In order to provide the dedicated HEP software environment, we use virtualization and container technologies.

In this contribution, we give an overview of the dynamic integration of opportunistic resources via TARDIS/COBalD in our HEP institute as well as how user analyses benefit from these additional resources.
STAR Data Production Workflow on HPC: Lessons Learned & Best Practices
Authors: Poat M D , Lauret J , Porter J , Balewski J
Published: July 2020

The Solenoidal Tracker at RHIC (STAR) is a multi-national supported experiment located at Brookhaven National Lab. The raw physics data captured from the detector is on the order of tens of PBytes per data acquisition campaign, which makes STAR fit well within the definition of a big data science experiment. The production of the data has typically run on standard nodes or on standard Grid computing environments. All embedding simulations (complex workflow mixing real and simulated events) have been run on standard Linux resources at the National Energy Research Scientific Computing Center (NERSC) aka PDSF. However, HPC resources such as Cori have become available for STAR’s data production as well as embedding, and STAR has been the very first experiment to show feasibility of running a sustainable data production campaign on this computing resource. The use of Docker containers with Shifter is required to run on HPC @ NERSC – this approach encapsulates the environment in which a standard STAR workflow runs. From the deployment of a tailored Scientific Linux environment (requiring many of its own libraries and special configurations required to run) to the deployment of third-party software and the STAR specific software stack, it has become impractical to rely on a set of containers containing each specific software release. To this extent, solutions based on the CERN VM File System (CVMFS) for the deployment of software and services have been employed in HENP, but one needs to make careful scalability considerations when using a resource like Cori, such as not allowing all software to be deployed in containers or bare node. Additionally, CVMFS clients are not compatible on Cori nodes and one needs to rely on an indirect NFS/DVS mount scheme. In our contribution, we will discuss our strategies from the past and our current solution based on CVMFS. Furthermore, running on HPC is not a simple task as each aspect of the workflow must be enabled to scale, run efficiently, and the workflow needs to fit within the boundaries of the provided queue system (SLURM in this case). Lastly, we will also discuss what we have learned so far about what is the best method for grouping jobs to maximize a single 48 core HPC node within a specific time frame and maximize our workflow efficiency.
The future of HEP software
Authors: Brun René
Published: July 2020

Any attempt to predict any future subject includes in general two components: extrapolations of the current trends and discussions about possible surprises. The extrapolation of the trends based on the latest function derivatives seems to be the easiest one. However, one has to be careful with fashionable trends and associated hype peaks. When one looks at the HEP software in the past 40 years, one sees regions of stability, often coinciding with the development and exploitation of a large accelerator, but also big changes when the hardware or/and software technology permits large steps. These large steps are often associated with surprises unthinkable a few years before. These two observations will likely continue to be true for the coming few decades, if not more. This paper is an attempt to analyze the current function derivatives based on similar analysis many years ago, and also propose some directions and developments that may become key components for our future software.
Direct optimization of the discovery significance in machine learning for new physics searches in particle colliders
Authors: Elwood A , Krücker D , Shchedrolosiev M
Published: July 2020

We introduce two new loss functions designed to directly optimize the statistical significance of the expected number of signal events when training neural networks and decision trees to classify events as signal or background. The loss functions are designed to directly maximize commonly used estimates of the statistical significance,

s
/

s
+
b

, and the so-called Asimov estimate, Za
. We consider their use in a toy search for Supersymmetric particles with 30 fb−1 of 14 TeV data collected at the LHC. In the case that the search for this model is dominated by systematic uncertainties, it is found that the loss function based on Za
can outperform the binary cross entropy in defining an optimal search region. The same approach is applied to a boosted decision tree by modifying the objective function used in gradient tree boosting.