bluuebunny/crossref_metadata_2025 huggingface dataset:
Fibrin Clot Properties in Cancer: Impact on Cancer-Associated Thrombosis
Authors: Ząbczyk Michał , Undas Anetta
Published: June 2023

Cancer is associated with a high risk of venous thromboembolism (VTE) and its recurrence. There is evidence that the prothrombotic fibrin clot phenotype, involving the formation of denser and stiffer clots relatively resistant to lysis, occurs in cancer patients, which is in part related to enhanced inflammation, oxidative stress, and coagulation activation, along with the release of neutrophil extracellular traps, indicating that fibrin-related mechanisms might contribute to cancer-associated thrombosis (CAT). Multiple myeloma and its therapy have been most widely explored in terms of altered fibrin characteristics, but prothrombotic fibrin clot features have also been reported in patients with active solid cancer, including lung cancer and gastrointestinal cancer. Patient-related factors such as advanced age, smoking, and comorbidities might also affect fibrin clot characteristics and the risk of CAT. Prothrombotic fibrin clot features have been shown to predict the detection of cancer in patients following VTE during follow-up. Cancer-specific therapies and anticoagulation can favorably modify the phenotype of a fibrin clot, which may alter the course of CAT. It is unclear whether the fibrin clot phenotype might help identify patients with CAT who are more likely to experience recurrent events. This narrative review summarizes the current knowledge on the role of fibrin clot structure and function in cancer patients in the context of CAT.
Agent behavior modeling method based on reinforcement learning and human in the loop
Authors: Huang Lin , Gong Li
Published: June 2023

Computer generated force (CGF) is one of the increasingly important research topics in the field of simulation. However, low modeling efficiency and lack of adaptability are acute problems of traditional CGF modeling. In this study, a method for modeling the agent behavior based on reinforcement learning and human in the loop is proposed to improve the ability and efficiency of agent behavior modeling. First, an overall framework for modeling the behavior of intelligent agents is constructed based on the deep reinforcement learning algorithm Soft Actor Critic (SAC) framework. Second, in order to overcome the slow convergence speed of the SAC framework, a method for human interaction and value evaluation in the loop is introduced, and the specific algorithm flow is designed. Third, in order to verify the performance of the proposed method, experiments are conducted and compared with algorithms using a pure SAC framework based on an example of agent completing specific tasks. Result shows that after 100 episodes of training, the task completion rate of the agent can approach 100% while a pure SAC framework require at least 500 episodes of training to gradually improve the completion rate. Finally, the results demonstrate that the proposed method can significantly improve the efficiency of agent behavior modeling and the task completion rate increases with the number of human interventions in the loop.
Free textbooks and other open educational resources gain popularity
Authors: Feder Toni
Published: June 2023

Affordable and customizable, they contribute to making higher education more inclusive and accessible.
Bilateral comparison of 10 pF and 100 pF standards (ongoing BIPM key comparisons BIPM.EM-K14.a and 14.b) between the NMIM (Malaysia) and the BIPM
Authors: Moreno J A , Gournay P , Dewi M K
Published: June 2023

Main text

This report presents the results of a bilateral comparison between the NMIM, Malaysia, and the BIPM, which was carried out using two 10 pF and two 100 pF travelling standards belonging to the BIPM, following an "A-B-A" pattern. The comparison at 10 pF forms part of the ongoing BIPM key comparison BIPM.EM-K14.a and that at 100 pF of the ongoing BIPM key comparison BIPM.EM-K14.b, where BIPM is the pilot laboratory for both comparisons.

The standards were measured during a total time of 19 weeks, from February 2022 to June 2022. The measurand of this comparison was the two terminal-pair capacitance of the travelling capacitors at frequencies of 1000 Hz and 1592 Hz, and a measuring voltage of 15 V (rms) for the 10 pF standards and 10 V for the 100 pF standards.

The results from the NMIM and the BIPM agree within a difference smaller than the relative expanded uncertainty of the comparison, which is dominated by the NMIM extrapolation of the BIPM calibrations, and to the use of a digital capacitance bridge to support the surveillance of the standards through periodical intermediate checks.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Experimental determination of dispersion diagrams over large frequency ranges for guided ultrasonic waves in fiber metal laminates
Authors: Barth Tilmann , Wiedemann Johannes , Roloff Thomas , Behrens Tim , Rauter Natalie , Hühne Christian , Sinapius Michael , Lammering Rolf
Published: June 2023

Fiber metal laminates (FMLs) are of high interest for lightweight structures as they combine the advantageous material properties of metals and fiber-reinforced polymers (FRPs). However, low-velocity impacts can lead to complex internal damage. Therefore, structural health monitoring with guided ultrasonic waves (GUWs) is a methodology to identify such damage. Numerical simulations form the basis for corresponding investigations, but experimental validation of dispersion diagrams over a wide frequency range is hardly found in the literature. In this work the dispersive relation of GUWs is experimentally determined for an FML made of carbon FRP and steel. For this purpose, multi-frequency excitation signals are used to generate GUWs and the resulting wave field is measured via laser scanning vibrometry. The data are processed by means of a non-uniform discrete 2d Fourier transform and analyzed in the frequency-wavenumber domain. The experimental data are in excellent agreement with data from a numerical solution of the analytical framework. In conclusion, this work presents a highly automatable method to experimentally determine dispersion diagrams of GUWs in FML over large frequency ranges with high accuracy.
Mode-locked orbits, doubling of invariant curves in discrete Hindmarsh-Rose neuron model
Authors: Muni Sishu Shankar
Published: June 2023

Similar to period-doubling bifurcation of fixed points, periodic orbits, it has been found since 1980's that a corresponding doubling bifurcation can also be found in the case of quasiperiodic orbits. Doubling bifurcations of quasiperiodic orbits has an important consequence on the dynamics of the system under consideration. Recently, it has been shown that subsequent doublings of quasiperiodic closed invariant curves lead to the formation of Shilnikov attractors. In this contribution, we illustrate for the first time in a discrete neuron system, the phenomenon of doubling of closed invariant curves. We also show the presence of mode-locked orbits and the geometry of one-dimensional unstable manifolds associated with them resulting in the formation of a resonant closed invariant curve. Moreover, we illustrate the phenomenon of crisis and multistability in the system.
Hypergeometric viable models in f(R) gravity
Authors: Hurtado Roger , Arenas Robel
Published: June 2023

A cosmologically viable hypergeometric model within the framework of the modified gravity theory f(R) has been derived based on the requirements of asymptotic behavior towards ΛCDM, the presence of an inflection point in the f(R) curve, and the viability conditions dictated by the phase space curves (m, r), where m and r denote characteristic functions of the model. To examine the constraints associated with these viability criteria, the models were expressed in terms of a dimensionless variable, namely R → x and f(R) → y(x) = x + h(x) + λ, where h(x) represents the deviation of the model from General Relativity. By employing the geometric properties imposed by the inflection point, differential equations were formulated to establish the relationship between

h
′
(
x
)

and h″(x). The resulting solutions yielded models of the Starobinsky (2007) and Hu-Sawicki types. However, it was subsequently discovered that these differential equations correspond to specific cases of a hypergeometric differential equation, indicating that these models can be derived from a more general hypergeometric model. The parameter domains of this model were thoroughly analyzed to ensure its viability.
The solvability of interval-valued Abel integral equations on a time scale with trigonometric representation of parameterized interval analysis
Authors: van Phut Lai , van Hoa Ngo
Published: June 2023

In this paper, the concept of the trigonometric representation of parameterized interval analysis is introduced to investigate a theory of the interval-valued Abel integral equation (IAIE) on a time scale. We provide suitable conditions to show that the IAIE on a time scale is solvable. Some simple examples are given to illustrate our main result.
Gravitational waves from eccentric extreme mass-ratio inspirals as probes of scalar fields
Authors: Zhang Chao , Gong Yungui , Liang Dicong , Wang Bin
Published: June 2023

We study eccentric orbits of the Schwarzschild spacetime for extreme mass ratio system (EMRI) in modified gravity theories with additional scalar fields.
Due to the additional energy and angular momentum carried away by the scalar field,
the orbit of the EMRI in modified gravity decays faster than that in general relativity.
The time that it takes the eccentricity e to reach the minimum is shorter and the values of the semi-latus rectum p and e at the turning point when e reaches the minimum are bigger for larger scalar charge d.
In addition to the calculation of energy fluxes with numerical methods,
we also use the Post-Newtonian expansion of the rate of energy carried away by the scalar field in eccentric orbits to understand the behaviors of the energy emission.
By adding the scalar flux to the open code FastEMRIWaveforms of the Black Hole Perturbation Toolkit,
we numerically generate fast gravitational waveforms for eccentric EMRIs with scalar fields
and use the faithfulness between waveforms with and without the scalar charge to discuss the detection of scalar charge d. The detection error of the scalar charge is also estimated with the method of the Fisher information matrix.
Design and analysis of high dynamic actuator and implementation on quadruped robot
Authors: Liang Z J , Jiang L , Zhao J X , Xing B Y , Xu P , Su B
Published: June 2023

Legged robot research is increasingly pursuing higher speed and higher dynamic manoeuvrability under higher load conditions, however, it poses more stringent challenges to the design of actuator. Under the constraints of actual size and weight restrictions, designing actuators that meet the requirements of high dynamic performance has become the pursuit of many robot designers, and has even become a key factor to limit and constrain the robot’s capability boundary. This paper takes the quadruped robot as the research object, and focuses on analysing the technical requirements of actuators under various gaits and working conditions, A 3-DOF pseudo-direct-drive actuator configuration scheme based on axial magnetic field is proposed. Under the control of the designed force-position hybrid control strategy, the test results of actuator and robot prove that the designed scheme can meet the high mobility with dynamic locomotion capability of the robot.
Research on fast matching method of suspension stiffness and damping based on unmanned special vehicle
Authors: Tang Zhi-yong , Lei Xu-Dong , Liu Hua , Feng Jie , Min Feng , Long Pei , Kan Lei
Published: June 2023

At present, the domestic research on the matching of stiffness and damping of the suspension system of unmanned special vehicles mainly adopts the empirical method and experimental method. This method is time-consuming and laborious, which prolongs the development cycle of unmanned special vehicles. In order to improve the vehicle ride comfort and reduce the research and development time, based on the single wheel two degree of freedom driving vibration model, this paper analyzes the influence of suspension stiffness and damping on the acceleration response of vehicle body, deduces the general calculation formulas of acceleration, suspension dynamic deflection and root mean square value of wheel dynamic load, and establishes the mathematical model of the optimal damping ratio of suspension system based on driving safety and comfort, The damping ratio design of the suspension system of an unmanned special vehicle is completed. The results show that this method can quickly and accurately complete the stiffness and damping matching design of suspension system, and shorten the time of vehicle design and development.
Ideal trajectory generation method of missile formation based on Gaussian pseudo-spectrum method
Authors: Zhang Benkang , Shen Jian , Wang Xiaoguang , Zhu Qingyu
Published: June 2023

With the increasingly complex combat environment and the diversity of combat tasks, important military targets are surrounded by multi-layer defense. Modern information warfare pays more attention to system confrontation and multi-system cooperative operations,and missile formation to attack targets is the main research content of this paper. For missile wing ideal trajectory generation problems, ensure the attack Angle of time and meet the design requirements, Gaussian pseudo-spectral method is used to generate guarantee missile attacks within the specified time shot on target, at the same time meet the attack Angle constraint at the end of the ideal trajectory, the more missiles cooperative engagement problems into the ideal trajectory tracking problem, avoid the estimate of the remaining time of flight.The main contents of this paper are as follows:(1) Gaussian pseudo-spectral method is used to generate the ideal trajectory model.(2)Use Matlab to simulate the established model.
A Weighted Fractional Fourier Transform Signal Synchronous Method based on Delay Multiplication for UAVs System
Authors: Zhang Xiaoyu , Fan Zhenzhen , Lv Zhenbin , Yu Xi , Yu Haiyang
Published: June 2023

Weighted fractional Fourier transform (WFRFT) is a novel anti-interception and anti-scanning communication method, which has been used in satellite communication system. On the analysis of the WFRFT signal and its characteristics, a synchronous method of WFRFT signal based on delay multiplication is proposed. This method estimated the rotation factor sequence by using delay multiplication, and demodulated the information by the estimated parameters. In addition, numerical simulations on AWGN channels are conducted to evaluate the performance of the proposed method according to average Bit-Error-Rate (BER) in different conditions of Signal-Noise-Rate (SNR). The simulation results show that the proposed method can effectively estimate the parameter and complete signal synchronization reliably.
Research on optimization and simulation of coordination of fuze and warhead for attack UAV based on damage trace model
Authors: Guo Yiran , Yang Chengwei , Li Juan , Mao Ruizhi , Guan Zhenyu , Li Jie , Chen Zihao , Li Jichu , Li Jiangtao , Ye Bobo
Published: June 2023

Facing the needs UAV of achieving intelligent and efficient damage for attack UAV in combat operations, there is a lack of research on the coordination of fuze and warhead for attack UAV considering the damage model and terminal trajectory correction. This paper proposes a novel method of the coordination of fuze and warhead to optimize the damage efficiency. A pilot-fight coordination simulation experiment is conducted under a certain actual combat background in the end. The method firstly gets the optimal detonation position and attitude results based on the simulated annealing algorithm and damage trace model. Then based on the trajectory planning results using the three-dimensional Dubins algorithm, the autonomous maneuver to the optimal detonation position and attitude considering the maximization of the damage effect are realized. The process of initiating battle and coordination is verified, and the feasibility and optimization effect of the developed algorithm are demonstrated. The research of this paper will also provide a new solution for the attack UAV pilot-fight operation control technology in practical application.
Integrated Guidance and Control Design for Guided Projectile Using Sliding Mode Method
Authors: Guan Jun , Yi Wenjun
Published: June 2023

According to the characteristics of special launch and flight environment such as high dynamic and large disturbance of guided projectile, the separate design method of traditional guidance system and control system will bring large errors, even affect the stability of the system, and the accuracy of projectile hitting the target is poor. In this paper, the guidance and control integrated control law of guided projectile is designed based on the sliding mode variable structure theory. The correctness, accuracy and stability of the designed control law are verified by numerical simulation. Numerical simulation shows that the guidance control integrated control law designed by sliding mode control theory can still have high control accuracy in the case of large perturbation. At the same time, Monte Carlo simulation shows that this method can meet the needs of engineering.
Research on Individual Performance Index of Air Cluster Combat Aircraft Based on Differential Game Theory
Authors: Liu Lei , Zheng Yuanxun , Lu Xinran , Du Lei
Published: June 2023

UAV cluster has the characteristics of low cost, large-scale and high autonomy, and has gradually become a new research direction in the field of military intelligence, and is widely used in combat tasks such as penetration reconnaissance, lure interference, large-scale saturation attack and regional sealing and control. Therefore, air cluster confrontation will become one of the main melodies of air combat in the process of confrontation, cluster aircraft individual performance index determines the overall cluster level, poor individual performance will make the cluster cannot effectively complete the task, excellent individual performance completes the task, but will bring the increase in the cost of cluster, so in the air cluster confrontation scenario, according to the target performance reasonable our individual performance has become important. Based on the innovative differential game theory, this paper studies the effective interception of the aircraft in the cluster high dynamic pursuit scenario, studies the relationship between the individual performance of the interceptor aircraft and the target aircraft, and effectively provides reference for the overall index design of the aircraft in the military field.
Dual-environment-driven MEMS pyrotechnic actuators
Authors: Li H , Luo J J , Xu X , Feng C Y , Liu T , Gao Y Y
Published: June 2023

In this paper, through the research on the driving mechanism and structure design of the MEMS silicon-based actuator that can realize the dual-environment force release function, a MEMS actuator that can be released from the dual-environment is designed. It is based on the mass-gear mechanism (inertial drive) centrifugal force drive design. The actuator can achieve 1.5mm output displacement under the control of 10V DC voltage, under the condition that the centrifugal is not less than 5000 r/min, it can realize the safety release function, and can resist overload 10000g. The micro-detonation device has a high degree of integration, initially realizes the function of releasing the force of the silicon-based inertial environment, and has good compatibility with MEMS technology.
Redundant architecture design and Human-machine system analysis of active side stick control system
Authors: Jian Li
Published: June 2023

This paper describes the advantages and disadvantages and principle of passive side stick and active side stick respectively. A redundant architecture of active side stick control system is proposed according to top-level function and safety requirements. The control unit with active-standby control channels, which has dissimilar command-monitoring hardware, can significantly improve the safety performance. Finally, the high angle of attack protection and high-speed protection of active side stick control system has been tested on one civil aircraft simulation platform, and it proves that the active side stick control system can effectively realize the tactile and warning function of envelope protection.
Research on high-speed bounding gait analysis and control of quadruped robot
Authors: Jiang L , Liu Y F , Wang Z R , Xing B Y , Tian C , Xu P , Liang Z J , Zhao J X
Published: June 2023

In order to improve the performance of the quadruped robot, the impact of high-speed gait is an important target to measure the performance of the robot. This paper elaborates the research methods of high-speed gait movement of quadrupeds, and a multi-rigid-body dynamics modelling method is presented. According to the analysis of high-speed bounding gait, the dynamic modelling of quadruped motion system is calculated. The motion planning for a rigid-torso quadruped robot based on Poincare Map is presented, and the high-speed bounding gait motion control strategy is established. The simulation experiments have been carried out, and the results have demonstrated the effectiveness of the motion planning model and high-speed bounding method.
Computational simulation study on disturbance of six-rotor UAVs due to ammunition launch
Authors: Zhenxiong Wang , Kai Kang , Xueying Hao , Huanming Hao , Jianghai Liu , Lang Cao
Published: June 2023

According to the multi-body dynamics theory, we analyzed and derived the influence laws of the ammunition launch angle, launch timing, mounting position, and mass on the stability of unmanned aerial vehicles (UAVs) by establishing a flight dynamics model of a six-rotor UAV in the process of ammunition launch. The analyses indicated that the ammunition launch angle, the longitudinal mounting position, and the multi-round ammunition launch timing significantly affect the disturbance of the UAV. When single-round ammunition is launched, selecting the appropriate ammunition mounting position can reduce the disturbance amplitude of the position of the UAV, and when multi-round ammunition is launched, the launch timing significantly affects the overall stability of the UAV. On the basis of the overall system and ammunition-related parameters, the optimal launch timing for different deployment methods can be derived. Through modeling analysis, we can qualitatively study the stability of the system during ammunition launch, providing a reference for the design of the ammunition launcher structure and the strike timing.
Study of External Energy Gun Automata Firing Control Based on Permanent Magnet Synchronous Motor
Authors: Li Changhong , Han Chongwei , Ma Jie , Zhang Gaosheng , Zhu Chao
Published: June 2023

In this paper, an external energy gun automata firing control method based on permanent magnet synchronous motor (PMSM) is presented. Firstly, on the basis of PMSM voltage equation and coordinate transform, current loop decoupling controllers are derived via the expected current closed loop time constant. The d-axis current and q-axis current can be tuned independently. Through the given mid-frequency interval criterion, the PMSM speed control method can be designed. Secondly, in order to implement the external energy gun automata firing control, the combined angle according to PMSM position and its over one circle count is solved first. The position controller is designed via Lyapunov stable theory. Last, an experiment is executed on a real external energy gun automaton and a PMSM position control system to verify the proposed method. The firing rate and firing shells length can be controlled. In order to decrease the firing rate without decrease PMSM speed, multiple single shells fired with given interval method can also be established and achieved. The experiment results verify the effectiveness of the proposed approach.
Terminal Explosion Power Test Flight Platform of Warhead
Authors: Hu Yunfei , Li Kang
Published: June 2023

Aiming at the shortcomings of high risk, high cost, low landing speed and low attitude accuracy of warhead terminal dynamic performance test, a low cost, recyclable and modular warhead terminal explosion power test flight platform is proposed. The overall scheme of two-stage flight is constructed, and the aerodynamic load of the flight process is analysed. In addition, the flight trajectory is designed. The numerical simulation results show that the flight platform can send the warhead to the specified test window, accurately control the drop velocity and attitude of the warhead in the test window, simulate the real flight environment of the warhead and the motion law of the terminal point. Therefore, the flight platform can realize the terminal explosion power test and test of the subsonic and supersonic warheads, providing technical support for the development of the warhead.
Modern Logistics Technology Based Ship Segment Outfitting Scheme
Authors: Qie Jinbo , Miao Yugang , Huang Minjian , Xie Ziming , Xie Xin
Published: June 2023

Shipbuilding occupies an important position in national defense and economy, which belongs to a typical large-scale complex production. In the modern shipbuilding mode, the segment outfitting process is the bottleneck of the whole shipbuilding. The outfitting cycle is long, and there are many resource constraints in the process. At present, China’s shipbuilding enterprises adopt the method of storage-yard based segment outfitting, which is relatively extensive in management and low in efficiency. This article points out that storage-yard based segment outfitting depends on complex dynamic scheduling, involving complex theoretical planning problems such as three-dimensional spatiotemporal coordination and flatbed transporter scheduling. Inspired by the segment outfitting line proposed in Germany and the modern logistics technology, the station design of the segment outfitting line was determined, and the centralized distribution with the intelligent logistics mode of outfitting parts is analyzed. The material and personnel coordination framework of the segment outfitting line is established. In the end, an assembly line based collaborative scheme of ship segment outfitting is proposed, with the characteristics of plan oriented, comprehensive perception, and dynamic synergistic.
Effects of pulse current waveform on electromagnetic railgun considering the eddy current effects
Authors: Li Yanzhao , Li Haiyuan
Published: June 2023

This paper investigates the effects of pulse current waveform on electromagnetic railgun considering the containment eddy current effects. First, a three-dimensional transient finite element model of the railgun with a metal containment and a pulse current waveform control model with constant feed energy are established. Then, taking the eddy current effect into account, the effects of different waveforms with constant feed energy on the eddy current, the rail current, the armature propulsive force, the rail repulsive force, the eddy current energy consumption, and the muzzle kinetic energy are analyzed. Finally, the simulation shows that reducing the slope of the rising edge of the pulse current can effectively suppress the eddy current and improve the muzzle kinetic energy. When the amplitude and the slope of the rising edge are determined, the excessively long flat top section will lead to more serious eddy current concentration at the ending moment of discharge, more eddy current loss, and less muzzle kinetic energy. Too high or too low amplitude of the pulse current is not conducive to the improvement of the muzzle kinetic energy. The investigation of this paper provides some references for the design of electromagnetic railgun and the selection of pulse current waveform.
Study on ballistic performance of metal matrix ceramic ball composite
Authors: Wang J H , Shi X M , Wang Q , Xia X , Fang X Z , Zeng T , Zhang L J , Ye C J
Published: June 2023

Different metal matrix ceramic composite plates were manufactured using different diameter ceramic balls. The ballistic resistance of these composite plates were investigated by firing 12.7mm, 25mm armor-piercing incendiary (API), and 200 standard explosively formed projectile(EFP). The tests results showed that these ceramic balls with higher mechanical properties performed better ballistic resistance, in the meantime, there was a correlation between diameters of the ceramic balls with projectile caliber. The quality protection factor of composite plate using 2mm diameter ceramic ball against 12.7mm armor-piercing incendiary (API) is better than 2.2; The mass effectiveness factor of composite plate using 6mm diameter ceramic ball against 25 mm armor-piercing incendiary (API) is better than 1.7; The quality protection factor of composite plate using 6mm diameter ceramic ball against 200 standard explosively formed projectile(EFP) is better than 3.5.
The effect of ceramic column shape on the ballistic performance of the SiC/UHMWPE composite armor-Numerical simulation
Authors: Hu Pengcheng , Zhao Fei , Yang Haifu , Cheng Yuansheng , Liu Jun , Zhang Pan
Published: June 2023

Composite armors are widely used in the protection of the human body and special vehicles due to their excellent ballistic performance. In this study, the ballistic impact response of SiC ceramics/Ultra-High Molecular Weight Polyethylene (UHMWPE) composite plate subjected to fragment simulating projectiles (FSP) is investigated numerically. The influences of the head shape of ceramic column and the impact position on the failure modes, ballistic limit velocity and energy absorption capacity are analyzed. Results show that ceramic plates have remarkable bulletproof property, and the projectiles will be smashed and plastically deform during the process of penetration. UHMWPE plates play a significant role in the energy-absorption of the composite armor against ballistic impact by experiencing the bulging deformation and delamination failure. The comparison of the ballistic limit indicates that the ballistic performance of ceramic/composite armors is associated with the head shape of the ceramic column and the impact location of the composite armor. The composite armor with flat nose ceramic columns shows superior ballistic limit over the one with flat nose ceramic columns. The findings of the present study aim to guide the design of the lightweight ceramic composite armor.
Numerical study on the influence of floating ice on the water-exit hydrodynamic characteristics of a trans-media vehicle
Authors: Wang Hao , Huang Zhengui , Guo Zeqing
Published: June 2023

In low-temperature combat conditions, the strong interference of floating ice on the water-exit process of trans-media weapons must be considered. The evolution of the cavity shape, hydrodynamic and ballistic characteristics during the water-exit process of a high-speed vehicle penetrating water (without floating ice) and ice-water mixture were studied in comparison based on computational fluid dynamics (CFD) and the discrete element method (DEM). The results revealed that the floating ice accelerates the collapse of the attached cavity, delays the collapse time of the tail cavity, and changes the vehicle’s wet degree. The floating ice causes the vehicle to be subjected to a severe fluctuating alternating load and lasts for a longer time, which changes the trajectory characteristics of the vehicle, reducing its motion stability and intensifying trajectory deviation. The findings can provide a reference for the design and development of cross-media weapons in low-temperature environments in winter.
Numerical analysis of launch process for a foldable quad-rotor UAV
Authors: Zhang Yiwen , Cheng Cheng , Lu Anzhi , Huang Zuozhenzi
Published: June 2023

Foldable quad-rotor UAV has the advantages of both artillery shells and rotor UAVs and can have the ability of long-distance rapid deployment and stagnation to perform tasks. To describe the rapid deployment process of gun-launched UAVs, a simplified internal ballistic and external ballistic modeling method is proposed. The ballistic parameters such as muzzle velocity, flight velocity variation, and flight trajectory are obtained. The effects of the variation of parameters such as initial pressure on the ballistic characteristics of the gun-launched UAV are analyzed. The research shows that the quad-rotor UAV can realize long-range rapid delivery and deployment after folding and pneumatic launching. With the increase of initial pressure, the muzzle velocity and range have a nonlinear increase. The related research results provide an important reference for the improvement of the subsequent gun-launched quad-rotor UAVs.
Study on Characteristics of Dynamic Equilibrium Angle of the Spin-Stabilized Projectile
Authors: Long Zhang , Linfang Qian
Published: June 2023

This study calculates and comparatively tests the dynamic equilibrium angle characteristics of the spin-stabilized projectile. Based on the analysis of the spatial relationships of angular motion of the projectile, a six-degrees-of-freedom (6 DoF) motion model is constructed. Through simulation and calculation, the changing law of the main parameters affecting the dynamic equilibrium angle with time is obtained, and then the whole-trajectory dynamic equilibrium angle curve is drawn using the law and the approximate formulas for dynamic equilibrium angle calculation. With the projectile-borne geomagnetic attitude testing technology, a dynamic equilibrium angle measurement method is developed. We combine this method with the trajectory angle curves, and work out the dynamic equilibrium angle values. The accuracy of the geomagnetic measurement is verified by comparing the angle of attack values obtained by geomagnetism and high-speed photogrammetry, and the credibility of the dynamic equilibrium angle measurement method is confirmed by comparing the measured and calculated values of the dynamic equilibrium angle. This study solves the problem of dynamic equilibrium angle measurement of spin-stabilized projectiles, and obtains the dynamic change curve of the dynamic equilibrium angle for the first time, which provids a new method and technology for the research on dynamic equilibrium angles.
BDS Position and Attitude Integration Measuring for Flying Spinning Vehicle
Authors: Yaojun Li , Xiaojuan Huang , Weigang Zhang , Kang Li
Published: June 2023

In order to meet the application requirements of position and attitude measurement of the flying spinning vehicle, a new integrated position and attitude measurement method based on single antenna is proposed in this paper. For the navigation requirements of the flying spinning vehicle, the traditional method is to use the satellite receiver for positioning, and at the same time, use the inertial navigation system or magnetometer for attitude measurement, the combination of the two is used to complete navigation and attitude measurement. The method proposed in this paper, on the one hand, is to reduce the number of components, greatly reduce the cost of use, on the other hand, to greatly improve the reliability of navigation and attitude measurement. Based on it, this paper uses satellite carrier signal and kinematic principle to carry out the vehicle attitude measurement based on satellite received signal. After analysis of satellite carrier amplitude signal received by the flying spinning vehicle, the mathematical relationship between carrier signal characteristics and spinning vehicle roll angle attitude is studied in further. Based on this, an integrated estimation method of satellite navigation and attitude measurement based on single antenna is proposed. At the same time, on account of the kinematics principle, satellite navigation is used to estimate the velocity vector without the use of inertial navigation system and magnetometer. Velocity vector is used for three-dimensional pseudo attitude kinematics mathematical modelling, and then by calculating and Euler attitude matrix transformation, the pseudo attitudes will be transformed into the inertial system coordinates. Experimental results show that the precision of attitude measurement can meet the actual engineering requirements.
Effect of various reinforcement shapes on the ballistic resistance of reinforced concrete slabs
Authors: Patnaik Gyanesh , Rajput A
Published: June 2023

Concrete structures are often subjected to extreme hazards such as projectile, missile impacts, crash, and blasts. So, evaluation of ballistic resistance of such structures against impact loading has become important. The present study is aimed to evaluate the effects of different shapes of reinforcement on the ballistic performance of slab to improve the state-of-the-art in protective design of structures. A finite element (FE) based model was framed in ABAQUS/Explicit to determine the perforation characteristics of reinforced concrete (RC) targets. The reinforced square targets were impacted by a rigid ogive nose steel projectile for wide range of velocities. Appropriate material models were adopted to simulate the response of concrete and steel reinforcement respectively. The model was validated with the experimental results and further, the validated model was used to perform the numerical simulations. The influence of various shapes of reinforcement on the ballistic resistance of RC targets was evaluated and compared. Among the compared shapes, the extended spiral reinforcement was found to have better ballistic performance. Consequently, the findings of this study can have implications in the design of protective structures.
Research on rotational angular velocity of preformed fragments
Authors: Jiahao Hou , Tong Zhuo , Zhiwei Guo , Yupeng Shi , Kai Sun
Published: June 2023

The rotational angular velocity of fragments under the driver of explosive products makes the fragments constantly flip during the trajectory, which has a huge effect on the velocity decay of the fragments. In order to more accurately calculate the residual velocity of the fragments during flight, it is necessary to study the rotational angular velocity of the fragments. Based on the paper target system, an experimental method for measuring the angular velocity of fragments is proposed. By using ANSYS/LSDYNA finite element software, the rotational angular velocity of preformed fragments under explosion is studied. A new meshing method is proposed to simulate the driven process of the explosive products on the fragments more accurately. The experimental results and the numerical simulation results are considered to be consistent within the margin of error. And at last, the distribution of fragment is studied base on numerical simulation. The research results provide a foundation for studying the trajectory of preformed fragments after explosive driven.
Experimental study on propagation characteristics of rotating detonation wave of liquid kerosene with oxygen-enriched air
Authors: Han Xinpei , Zheng Quan , Huang Hanli , Xu Pufeng , Wu Xingang , Weng Chunsheng
Published: June 2023

In order to study the propagation characteristics of rotating detonation wave (RDW) of liquid fuel, an experimental study was carried out with liquid kerosene at room temperature as fuel and oxygen-enriched air with oxygen volume fraction of 38.5% as oxidant in this paper. RDW with equivalence ratio in the range of 0.65~0.9 was successfully obtained by controlling kerosene mass flow, and a detailed analysis of propagation characteristics of RDW was carried out. The results show that with the increase of equivalence ratio, the propagation state of RDW gradually changes from the premature flameout of discontinuous detonation to the complete operation of continuous detonation. The flow blockage of the injectors will further worsen the mixing effect under low equivalence ratio conditions, resulting in the discontinuous detonation phenomenon of repeated flameout-initiation process in the combustion chamber. In this study, almost all detonation waves operate in two-counter RDW mode, except that there is a single wave mode in a short period after flameout-initiation process.
Experimental and simulation investigations on perforation of titanium alloy plates against armor-piercing projectile at oblique impacts
Authors: Zhao Li , Xuguang Sun , Zhongfeng Zhou , Xiaoce Sun , Sicong Qiu , Cheng Liu
Published: June 2023

Titanium alloy is an advanced lightweight armor material, widely used in armored vehicles. Experimental and simulation investigations on perforation of titanium alloy plates impacted by armor-piercing projectiles were performed in this study. The critical ricochet angle and failure morphology of 6 mm, 8 mm, 10 mm and 12 mm titanium alloy plates subjected to projectiles were obtained. Simultaneously, Numerical simulations of the oblique perforation of titanium alloy plates were then performed on the high-performance computer using the explicit finite element code LS-DYNA, and the validity of the numerical model was verified by comparing with the experimental results. Furthermore, typical process of projectile oblique penetration into titanium alloy target plate was analyzed and the influence of factors such as inclination angle and thickness on the ballistic performance of titanium alloy plates were discussed. It is found that the residual velocity of the projectiles decreases with the increase of inclination angle of target, indicating that increasing the inclination angle of the target plate can significantly reduce the perforation performance of armor-piercing projectile. In addition, the critical ricochet angle of titanium alloy plate is sensitive to its thickness, and larger thickness can reduce the critical ricochet angle of the titanium alloy plate.
Effects of Engine on Penetration Performance of Semi-Armor Piercing Warhead
Authors: Liu Ji’an , Gu Wei , Jing Tong , Yu Wanqian , Gao Hongchao
Published: June 2023

In the structural layout of missiles and rockets, the engine is generally placed behind the warhead. In order to investigate the effects of the engine on the penetration performance of semi-armor piercing (SAP) warheads, this study numerically simulated the oblique penetration of an SAP warhead and a free-flight rocket into armor plates. The results showed that under the condition of oblique penetration, the compressive force the warhead underwent was asymmetric and that attitude changes made the body of the warhead easily compressed by the target plate. In addition, the constraint of the engine was found to suppress warhead deflection and reduce projectile deformation.
Numerical research of high-speed oblique water-entry of projectile based on rigid body and fluid-structure interaction model
Authors: Liu Xiangyan , Huang Zhengui
Published: June 2023

When a projectile enters the water at high speed, the projectile can suffer a huge impact of water. If a deformation occurs in the structure of the projectile during water-entry, the numerical method based on rigid body model will be limited, while the accuracy and precision of the results can be affected. The two numerical methods of the rigid body and fluid-structure interaction (FSI) model have been built to get the results of the oblique water-entry of the projectile in this paper. Moreover, the numerical results for the given projectile under the same water-entry conditions (initial angle of incidence of θ = 15°, initial angle of attack of α = 5°, initial speed of V = 200m/s ) have been contrasted. The results show that if a small deformation occurs in the body of the projectile during the water-entry, the numerical results of the FSI and the rigid body are different. Further, the small deformation within the limit of flexibility can change the motion attitude and the trajectory of projectile during the water-entry, meanwhile the change can cause the bending of the ballistic and the super-cavity. For the projectile with the structural response, the change in the distribution of the stress concentration area can affect the drag force suffered by projectile.
Analysis of muzzle flow field of asynchronous firing of multi barrel aircraft gun under strong convection
Authors: Xie Jingyun , Guo Zhangxia , Yuan Zekun , Jin Yinxiang , Zhang Jiangchen
Published: June 2023

Based on the N - S equation and the k-ε model, this article uses the dynamic grid technology to finish the numerical simulation of projectile-barrel coupling for muzzle flow field of the double-barreled aircraft gun during asynchronous firing under different incoming Mach numbers and different firing intervals. The influence law of muzzle flow field on projectile motion is studied. The results show that when there is supersonic incoming flow, the radial force on the projectile will increase with the increase of incoming Mach number. At the same time, the larger the Mach number, the earlier the radial force of the projectile will be affected. Under the same inflow Mach number, the radial force on the projectile when the double-barreled aircraft gun is fired asynchronously is significantly lower than that when fired synchronously. The larger the firing interval, the smaller the radial force on the projectile.
Research on the Trajectory Consistency based on Mahalanobis distance method
Authors: Xin Zhao , Yongxiang Ji , Xibin Luo , Shefeng Liu , Xiaolei Ning
Published: June 2023

For the average trajectory consistency test, the density is good, which leads to the problem of poor consistency. This paper proposes to use the Mahalanobis distance method to process the test data of two kinds of ammunition. First, each pair of values in a set of tests is obtained through experiments. The obtained data is processed by the Mahalanobis distance method for relative distance processing. Then the mean and variance of the distance data of the two ammunition are calculated. In the simulation test, the data of tests which are processed by the Mahalanobis distance method. The consistency of the two ammunition is checked according to the trajectory consistency test method. The test data using the Mahalanobis distance method can better than the data of the two ammunition in the consistency. The test data processed by the Mahalanobis distance method can improve the situation of good density and poor consistency in the consistency test, and provide technical support for the subsequent average trajectory consistency test.
Study on the Multiphase Flow Mechanism of Coupling Gas-dust Coupling Explosion in Open and Closed Vessels
Authors: Yang Zhou , Jing Qi , Liu Qingming , Liu Changqi , Wang Zhisong , Shen Yang , He Zongling
Published: June 2023

In order to study the flame propagation characteristics and influencing factors of gas-coal dust mixed explosion in containers, this paper quantitatively explores the effect mechanism of two-phase concentration ratio and closed section restraint mode on gas-coal dust coupling explosion by numerical simulation, comprehensively considering the coal pyrolysis model and the two-phase mass and heat transfer model. The current research results show that: in closed pipeline, with the increase of pulverized coal concentration, the gas explosion intensity of lean fuel shows a trend of first increase and then decrease. Under the methane concentration of 7%, the optimal concentration of pulverized coal is 100 g/cm3; a similar trend also occurs in the open pipe. Secondly, the two-phase flame propagation speed in the closed pipe is faster than that in the open pipe. The research results of this paper can provide scientific guidance for the prevention and control of coal mine explosion accidents.