bluuebunny/crossref_metadata_2025_split huggingface dataset:
Upper bound efficiency for thermal radiation energy conversion by using spectrally selective electrical, chemical and mechanical work extractors
Authors: Badescu Viorel 
Published: May 2023

Abstract
The maximum work content factor

κ

U
,
i

+

of the incoming thermal radiation energy depends on the temperatures of the radiation source, work extractor and environment, on the solid angle subtended by the radiation source, and on the spectrally averaged absorptance and emittance of the work extractor. The theory is applied to solar radiation as a particular case. The formula derived here for

κ

U
,
i

+

is more accurate than well-known formulas from literature. The work extractor may provide work or not, depending on the averaged absorptance and emittance and radiation concentration. Solar thermal power plants based on plane blackbody collectors cannot provide work under unconcentrated solar radiation.
Gravitational wave from graviton Bremsstrahlung during reheating
Authors: Barman Basabendu , Bernal Nicolás , Xu Yong , Zapata Óscar 
Published: May 2023

Abstract
We revisit graviton production via Bremsstrahlung from the decay of the inflaton during
inflationary reheating. Using two complementary computational techniques, we first show that such
3-body differential decay rates differ from previously reported results in the literature. We then
compute the stochastic gravitational wave (GW) background that forms during the period of
reheating, when the inflaton perturbatively decays with the radiative emission of gravitons. By
computing the number of relativistic degrees of freedom in terms of Δ N
eff, we
constrain the resulting GW energy density from BBN and CMB. Finally, we project current and future
GW detector sensitivities in probing such a stochastic GW background, which typically peaks in the
GHz to THz ballpark, opening up the opportunity to be detected with microwave cavities and
space-based GW detectors.
Dynamical consistency conditions for rapid turn inflation
Authors: Anguelova Lilia , Lazaroiu Calin Iuliu 
Published: May 2023

Abstract
We derive consistency conditions for sustained slow roll and rapid turn inflation in
two-field cosmological models with oriented scalar field space, which imply that inflationary
models with field-space trajectories of this type are non-generic. In particular, we show that
third order adiabatic slow roll, together with large and slowly varying turn rate, requires the
scalar potential of the model to satisfy a certain nonlinear second order PDE, whose coefficients
depend on the scalar field metric. We also derive consistency conditions for slow roll
inflationary solutions in the so called “rapid turn attractor” approximation, as well as study
the consistency conditions for circular rapid turn trajectories with slow roll in two-field models
with rotationally invariant field space metric. Finally, we argue that the rapid turn regime
tends to have a natural exit after a limited number of e-folds.
CONNECT: a neural network based framework for emulating cosmological observables and cosmological parameter inference
Authors: Nygaard Andreas , Holm Emil Brinch , Hannestad Steen , Tram Thomas 
Published: May 2023

Abstract
Bayesian parameter inference is an essential tool in modern cosmology, and typically requires the calculation of 105–106 theoretical models for each inference of model parameters for a given dataset combination. Computing these models by solving the linearised Einstein-Boltzmann system usually takes tens of CPU core-seconds per model, making the entire process very computationally expensive.

In this paper we present connect, a neural network framework emulating class computations as an easy-to-use plug-in for the popular sampler MontePython. connect uses an iteratively trained neural network which emulates the observables usually computed by class. The training data is generated using class, but using a novel algorithm for generating favourable points in parameter space for training data, the required number of class-evaluations can be reduced by two orders of magnitude compared to a traditional inference run. Once connect has been trained for a given model, no additional training is required for different dataset combinations, making connect many orders of magnitude faster than class (and making the inference process entirely dominated by the speed of the likelihood calculation).

For the models investigated in this paper we find that cosmological parameter inference run with connect produces posteriors which differ from the posteriors derived using class by typically less than 0.01–0.1 standard deviations for all parameters. We also stress that the training data can be produced in parallel, making efficient use of all available compute resources. The connect code is publicly available for download on GitHub (https://github.com/AarhusCosmology/connect_public).
Spin effects on the relativistic strong EM wave modes in magnetized plasma*
Authors: Hu Qiang-Lin , Hu Wen , Xiao Jin-Peng 
Published: May 2023

Abstract
Based on the relativistic hydrodynamic model of EM wave–spin plasmas interaction, the spin effects on the relativistic strong EM modes in magnetized plasma are investigated. The dispersion relations of the EM wave propagating parallel and perpendicular to the external magnetic field are obtained. Results show that the strong EM wave modes are affected by the time component of four-spin as well as the increase of electron effective mass. Especially in the case of EM wave propagating parallel to the external magnetic field, the time component of four-spin amplifies the influence of spin effects on the low-frequency modes obviously.
Study on Maneuvering Target Trajectory Simulation and Tracking Based on IMM algorithm
Authors: Ma J R , Ma Q H , Yang S J , Zheng J Q , Wang S W 
Published: May 2023

Abstract
On the background of air defense missile which use radar command guidance, this article focuses on the maneuvering target trajectory simulation and tracking problem by considering possible maneuvering modes and target overload. Taking Serpentine maneuvering (S maneuvering) as an example, the target trajectory is simulated based on overload using stepwise design method, and data are measured through sensor models. Since single model cannot model the maneuvering target motion exactly, the estimation is addressed by combining the interacting multiple model algorithm and unscented Kalman filter algorithm, so as to study the applications of maneuvering target trajectory simulation and tracking in air defense missile systems. The effectiveness of the algorithm is demonstrated with simulated data.
Application of High Kinetic Energy Buffer Control Technology after Free Recoil
Authors: Ke B , Qian L F , Niu T H , Zhang L , Wang H F , Jia Q 
Published: May 2023

Abstract
Aiming at the problem of high recoil kinetic energy caused by launching long-range guided projectiles, the main effect and Pareto of barrel diameter, projectile mass, initial velocity and charge on recoil kinetic energy are studied based on Latin hypercube test design under certain bore pressure conditions, which provides reference for the evaluation and control of high recoil kinetic energy brought by new ammunition. At the same time, in order to solve the difficulty of free recoil high kinetic energy buffer braking, four mathematical models and technical schemes of recoil buffer braking are introduced and designed, and the buffer characteristics are compared and analyzed. Based on the analysis of reducing the buffer force and the length of recoil motion, a free recoil test bench scheme for the combination of blocking cables and recoil buffer devices is also proposed. The recoil braking force is planned based on NCGA intelligent optimization algorithm. The results show that the combined buffer braking principle is feasible and the buffer effect is good.
Improved overturning moment calculation method for large caliber artillery based on dynamics analysis
Authors: Xu Yao-feng , Gu Bin , Lei Jian-ping , Shan Chun-lai , Liang Hui 
Published: May 2023

Abstract
The effect of launch load on rotating parts is very complicated during firing of large caliber artillery. In the design of artillery firepower system, the traditional method to derive artillery overturning moment by taking the elevating part as the analysis object and using the static equilibrium equation cannot accurately reflect the real state of artillery firing. Therefore, taking the whole gun dynamics simulation as the analysis method and combining with the shooting test data, the force state of the elevating mechanism is obtained. The dynamic simulation results, the calculation results of the traditional formula, the measured results of the shooting test and the attitude change of the gun monitored by high-speed camera are compared and analyzed. The result shows that the turret race shaking is an important factor affecting the accuracy of design and simulation calculation. When the turret race shaking is considered, the simulation results are consistent with the experimental results, but inconsistent with the calculation results of the traditional design formula; The simulation results without considering the turret race shaking are consistent with the results of the traditional design formula, but they are different from the test results. Considering the influence of the angular acceleration of the rotating part given by the turret race shaking, the overturning moment formula is improved, and the force analysis formulas of the rotating part and the elevating part are carried out respectively and the calculation results of the improved formula are in good agreement with the test results. The research complements the calculation method of the overturning moment of the gun, which can be extended to the design of key components such as elevating mechanism and gun carriage.
Application of Supercavitation Technology in Anti-submarine Combat Equipment of Gun Platform
Authors: Qi XB , Wang R , Wang JW , Liang JQ , Li RJ 
Published: May 2023

Abstract
With the increase of anti-submarine depth and anti-submarine distance, the current anti-submarine warfare becomes more and more difficult. In this paper, the development status of anti-submarine weapons and equipment are summarized, and the shortcomings of existing anti-submarine warfare modes are analyzed. This paper describes the development status and advantages of supercavitation weapon, puts forward a preliminary assumption of developing supercavitation anti-submarine ammunition based on gun platform by using supercavitation technology, and makes simulation calculation on the ballistic performance of supercavitation anti-submarine ammunition. At the end of the paper, the application prospect of this type of anti-submarine ammunition is prospected.
Applications of Supercavitation Drag Reduction Technology in Naval Gun Underwater Attack and Defense Warfare
Authors: Wang R , Yao Z , Qi XB , Li RJ , Wang JW 
Published: May 2023

Abstract
China has lagged behind in the construction of underwater attack and defense system for a long time, and there is still a lack of effective means for rapid anti submarine and underwater short-range / terminal defense in large areas. This paper analyzes the characteristics of underwater combat targets and equipment, and puts forward the combat mode of naval gun underwater attack and defense system based on supercavitation drag reduction technology. This paper expounds the application and development status of supercavitation drag reduction technology in the field of gun weapons, analyzes the key technologies involved in the development of naval gun underwater attack and defense combat, and looks forward to the application prospect of new naval weapons, which can provide technical support for improving the comprehensive combat capability of naval gun.
Development of a shooting strategy to neutralize UAV swarms based on multi-shot cooperation
Authors: Shaohui Xue , Ji Fan , Baohua Wang , Fengge Wang , Yong Hou , Jiajia Ma , Ye Wu 
Published: May 2023

Abstract
Economical and efficient assault methods using drones and drone swarms severely assailed the defenders during the conflict in the Middle East. In view of the current situation, based on medium and large-caliber anti-aircraft artillery platforms, this article analyzes and calculates the advantages of using multiple anti-aircraft guns against drones, the threat of a drone colony, and the drone colony density. Additionally, this study determines the firing sequence of a drone swarm, and provides anti-aircraft gun firing position points to reduce the firing cost and increase the efficiency. This ensures the optimization of an air defense system within a short duration of time. Ammunition is an effective defense against drone swarms. The experimental results demonstrate that compared with that of the conventional methods of individually shooting the swarms, this strategy can simultaneously neutralize multiple targets, assign shooting tasks to multiple artillery guns, and can cause greater damage to a drone swarm.
Simulation Research of rigid chain failure in a modular gunpowder delivery machine
Authors: Jian Wang , LongMiao Chen , Liu Yang , JunWei Li , ZhiGang Li 
Published: May 2023

Abstract
Based on the theory of a low-recoil rarefaction wave (RAVEN) gun firing cased telescoped ammunition (CTA), the models of interior ballistics and dynamics were established. The dynamic characteristic curves were obtained by numerical simulation analysis, and the results were verified by firing tests. Compared with traditional closed-breech guns, the low recoil force swing chamber gun keeps the projectile’s muzzle velocity basically unchanged, while the maximum recoil is reduced by up to 74%. Based on these results, the parameters of the inertial breech buffer spring were optimized while the maximum recoil force of the breech reduced by 14.2% without affecting system performance and structural installation size, which effectively improved the overall performance of the weapon system.
Numerical Simulation on the Muzzle Shock Wave Pressure for Aircraft Gun
Authors: Tian Nan , Li Yong , Wang Kaizheng , Liu Jie , Xie Yangyang , Liu Bin 
Published: May 2023

Abstract
The muzzle shock wave has a great impact on the airborne structure, airborne personnel and airborne equipment. Therefore, the muzzle flow field of the aircraft gun is used as the research object, based on the three-dimensional reynolds-averaged Navier-Stokes control equation and the standard k − ε turbulence model, a finite element simulation model of the powder gas motion process in the after-effect period without considering the projectile motion is established, the adaptive grid technique is used to divide the mesh inside the barrel and the muzzle brakes, and the The finite volume method is applied to numerically calculate the flow field control equations at the muzzle to obtain the muzzle shock wave pressure with the muzzle brakes and its development law, and to build an experimental verification platform to verify the accuracy of the simulated shock wave pressure. The research results show that the established finite element simulation model of the muzzle flow field can accurately predict the muzzle shock wave pressure.
Research on Application of Three Closed-loop Autonomous Current Sharing Control Technology in Artillery Power System
Authors: Zhang Zhipeng , Liu Qitao , Wang Tianshi , Gu Shuanghao , Ma Jie 
Published: May 2023

Abstract
The new artillery power system adopts the power supply mode of multiple power modules in parallel, which has the advantages of strong versatility, high power, high reliability, and low cost. The main difficulty lies in the current sharing of the power supply modules. Aiming at the shortcomings of traditional current sharing method such as low current sharing accuracy, poor dynamic response, poor output voltage stability, and low anti-interference ability, this article analyzes the necessity of parallel power supply current sharing and the principle of traditional average current sharing method, based on average current sharing method, a three-closed-loop autonomous current sharing control method is proposed, and a system model of power supply modules operating in parallel is established to realize the intelligent and autonomous average current distribution of power supply modules operating in parallel in the artillery power system to meet the power required by the load in the system. Through simulation analysis and prototype test, it is verified that the three closed-loop autonomous current sharing control has the advantages of high current sharing accuracy, fast dynamic response, good stability and strong robustness.
Disturbance Observer based Backstepping Control for Electro-hydraulic Position Servo System of the Projectile Coordination Arm
Authors: Fan Rui-dong , Qian Lin-fang , Chen Guang-song , Wei Yu-kai 
Published: May 2023

Abstract
Due to the existence of unmodeled friction and unknown load disturbance, the position tracking control of electro-hydraulic position servo system of projectile coordination arm becomes an important problem to be solved urgently. In this paper, a dynamic surface backstepping control strategy is proposed based on the disturbance observer(DOB). To be specific, the disturbance observer is applied to estimate the unknown disturbance force, and the backstepping controller realizes the position tracking control. In order to improve the position tracking performance, The estimated value of the observer output is brought into the backstepping controller to realize the model compensation of the disturbance. Meanwhile, the dynamic surface method is utilized to handle the differential explosion problem in the backstepping method. The global stability of the closed-loop system is verified by Lyapunov stability theory. The co-simulation results show that the proposed method can effectively compensate the unknown disturbance in the electro-hydraulic position servo system, and has better tracking performance and strong robustness.
Development Status and Trend of Stealth Technology of Tactical Missiles
Authors: Xu D G , Liu J S , Luo S , Li P 
Published: May 2023

AbstractIn modern warfare, precision guided munitions have become one of the major equipment to attack and hit the enemy’s crucial value targets. In addition, they are the critical targets of the missile defense and anti-aircraft interceptor system of varying countries during interception and destruction, and the world has increased investment in missile defense. Therefore, the penetration and countermeasures capacities of missiles holds the key to the victory, and the stealth technology of tactical missiles provides a vital orientation for the future advancement of weapons and equipment technology. Based on the current military requirements, this paper summarizes the application of stealth technology in varying tactical missiles and analyzes the development trend of such technology in the future, which is expected to have great implications for further research and application of both stealth and anti-stealth technology.
Aerodynamic characteristics of Spin-stabilized Projectile at High Angle of Attack
Authors: Yang B Q , Zhang L , Shen Q , Liu L X , Shi C 
Published: May 2023

Abstract
Researching the aerodynamic characteristic of projectile at high angle of attack could serve to determine the launching condition and the design method of aerodynamic configuration. The aerodynamic coefficients of a kind of spin-stabilized projectile were calculated and analyzed by CFD. An efficient and precise method of calculating the pitching damping moment was obtained to research the aerodynamic coupling characteristic of spinning motion and pitching motion. The results showed that the aerodynamic coefficients of projectile at high angle of attack was nonlinear, the pitching damping moment was proportional to the pitching angular velocity, magnus force had hysteresis characteristic which was affected by pitching amplitude and frequency.
Modeling and Calculation of Hydraulic Equation of Recoil Brake Which is Unfilled in counterrecoil throttling Chamber
Authors: Yang JM , Yu YN , Shi CM 
Published: May 2023

Abstract
In order to lower muzzle vibration, the major caliber gun reduced the recoil resistance in the in_bore period. When the recoil brake was designed, throttling area was enlarged to reduce the hydraulic resistance. This made the counterrecoil throttling chamber (III chamber) was unfilled in the beginning of recoil. In the middle of recoil, III chamber was filled all of a sudden. This made the pressure in the working chamber (I chamber) and III chamber and the recoil resistance increase sharply. According to the equation, Hydraulic equation of recoil brake was set up when the III chamber was unfilled. The conditon of that III chamber was unfilled was deduced. Recoil mechanism was designed in this algorithm, and the recoil motion was computed in compare to the tested curevs. The result indicated that computation result matched well with the actual test result. This study offered reference of design of this kind of recoil mechanism.
Applications of Chromatic Confocal Technology in Precision Geometric Measurement of Workpieces
Authors: Ma YD , Xiao YC , Wang QQ , Yao K , Wang XR , Zhou YP , Liu YC , Sun Y , Duan J 
Published: May 2023

Abstract
Chromatic confocal technology is increasingly applied in industries that require high-precision geometric measurements such as aerospace, naval ordnance, and medical electronics owing to its advantages in testing accuracy, real-time performance, anti-interference, and no damage to tested workpieces. This paper introduces the measurement principle of chromatic confocal technology and the structure of chromatic confocal sensors, and enumerates several typical application scenarios of the technology from the aspects of thickness measurement, profile, 3D topography scanning, roughness measurement, and wafer comprehensive parameter measurement. It also looks into potential development directions of chromatic confocal technology.
The Application of Grooveless Remelt Deposit Welding to the Joining of Large-Caliber Thin-Walled Projectile to Guide Band
Authors: Yang L , Liu W J , Liang J F , Li M , Zhang P J , Wang H , Li X L 
Published: May 2023

Abstract
This paper introduces the research on guide band welding in China and other countries, analyzes the characteristics of guide bands produced by remelt deposit welding and the application of the welding process to the joining between thin-walled submunition-based projectiles with a large caliber and launched by a howitzer. In addition, this paper raises the performance testing requirements for the grooveless remelt deposit welding process.
Development of Graphene /PBO Nanocomposite
Authors: Meng ZR , Liu Q , Zhong WH , Dai Y 
Published: May 2023

Abstract
The study of graphene/poly (p-phenylene benzobisoxazole) (PBO) nanocomposites in recent years is introduced, while the research interests and application fields of graphene/PBO nanocomposites in the future are prospected in this review. In the process of polymer formation, two modification methods, in-situ polymerization modification and blending modification are mainly used to improve the dispersion uniformity of graphene in the PBO matrix. The polymer can be divided into the surface modification of PBO fiber and the modification of PBO nanofiber according to the existing state of PBO, and the effects of two modification methods on mechanics, thermal characteristics, surface morphology and aging resistance of graphene/PBO nanocomposites are compared.