bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel method based on the calculus of variations to optimize the cooling passage configuration in thermal protection structure
Authors: Li Xuan , Wu Shujie , Zhang Qun , Li Xin , Chen Shiqiang
Published: May 2024

A novel method based on the calculus of variations to obtain the optimization of cooling structure was developed in this work. The optimization of heat sink designs for better heat-dissipating effects has been researched substantially. However, the optimization of cooling passage configurations in thermal protection structures to improve the comprehensive heat transfer performance has remained a long-term interest and unsolved problem for researchers. Due to the intrinsic complexity, the laminar flow is usually considered before while the turbulent flow is seldom treated. It is valuable to provide timely and effective solutions to optimize the cooling structure, where the turbulent flow is involved, for practical use. A novel method to optimize cooling structure based on the calculus of variations has been developed to meet this need. The average temperature, temperature inhomogeneity, and coolant flow pressure drop were chosen as objective functions. The cooling channels can be established depending on the geometric and thermal boundary conditions of the structure, and then the quasi-three-dimensional simulation of the fluid/solid coupling field was calculated to get the temperature distribution of the cooling structure, the pressure drop, etc. Hence, this work explores the feasibility of combining coupled heat transfer and the calculus of variations to realize optimal cooling channels. By the novel method, the minimum objective function can be obtained.
Numerical simulation of the water landing process of a light civil helicopter in level 5 sea conditions
Authors: Zhu Yuanchun , Sun Libing
Published: May 2024

A helicopter emergency flotation system can provide flotation capability after the helicopter accidentally falls into the water. To solve the problem of attitude change of a helicopter after landing in water, a numerical simulation was carried out on a light civil helicopter with a weight of 3.5 t. It was simulated in level 5 sea conditions, the traveling speed was 15.4 m/s, and the height of the lowest point of the hydrostatic helicopter from the water surface was 250-260 mm, with or without lift, with or without floats. Landing on the water can be done with either basic or elliptical floats and in three different postures. The simulation results show that equipping a helicopter with pontoons can significantly improve its overturning resistance and flotation capabilities, but the impact on a helicopter equipped with pontoons will increase. Landing a helicopter in the water at a certain elevation angle is beneficial to the stability of the helicopter. A helicopter with a basic pontoon is more stable when it lands in the water. The performance is higher than that of the ellipsoidal pontoon, but the pitch stability of the basic pontoon is lower than that of the ellipsoidal pontoon.
Study on aero engine thermal performance analysis using a new mathematical model of isentropic expansion (compression) process
Authors: Haifei Zheng , Xiqiao Yu , Hao Tang
Published: May 2024

At present, for the research of aero engine performance, it is necessary to calculate the overall thermal performance of the aero engine at the beginning of the research. For the mathematical model of the isentropic expansion (compression) process, most researchers use the ideal state value to calculate in the mathematical model, so that the calculated results have a certain error compared with the actual value. Therefore, the new isentropic expansion (compression) process mathematical model based on the Φ function is applied in this paper to the technical aero engine overall thermal performance calculation. After calculation and analysis, it is concluded that the calculation accuracy of the mathematical model provided in this paper is higher than that of the literature program for the overall thermodynamic performance parameters of the aero engine, whether it is the thrust of the aero engine, the unit fuel efficiency, or the thermal efficiency of the aero engine. It shows that it is feasible to revise and improve the mathematical model of isentropic compression and isentropic expansion process in this paper, more accurate calculation results can be obtained by using the new model in the performance analysis program, and more accurate numerical analysis can be carried out.
Design and thermal protection performance analysis of insulated wing storage box for hypersonic variable-sweep aircraft
Authors: Dai Shuhao , Ji Hongli , Tao Chongcong , Zhang Chao , Qiu Jinhao
Published: May 2024

Utilizing variable-sweep wing technology can further enhance the flight performance of hypersonic aircraft in a wide range of high-altitude, high-speed environments. Existing research on hypersonic variable-sweep flying wings has mainly focused on aerodynamic shape design, with limited research on the internal thermal protection of the aircraft. This study firstly investigates the performance improvement of a hypersonic flying wing using variable-sweep technology through CFD simulations. Secondly, to address the high-temperature issues induced by variable-sweep wings, an insulated wing storage box with a corrugated structure is designed, incorporating a thermal insulation layer made of corrugated webs and insulating materials. Heat transfer simulations are conducted by applying thermal loads to the wing storage box to study the temperature distribution during the variable-sweep process. Finally, a comparison between the corrugated structure design and the non-corrugated structure design of the wing storage box is performed to analyze the thermal insulation performance of the insulation layer. The results show that the heated area of the wing storage box is primarily influenced by the wing’s sweep angle, and the corrugated thermal insulation layer can effectively reduce heat transfer efficiency, resulting in a 30% reduction in the external temperature of the wing storage box.
Numerical simulation of supersonic combustion chemical reactions based on multi-GPUs
Authors: Lai Jianqi , Lu Fengshun , Hu Xingzhi , Hou Lin , Wang Zhiren , Jiang Xiong
Published: May 2024

To achieve a large-scale and efficient numerical solution to supersonic combustion chemical reaction problems, a numerical simulation algorithm for combustion chemical reactions was established on a graphics processing unit (GPU). Numerical simulation of the combustion chemical reaction of a hydrocarbon fuel/air mixture in a supersonic combustor was conducted to verify the accuracy of GPU parallel calculation results and analyze its parallel performance. Numerical results show that GPU parallel computing can accurately simulate the complex flowfield in the combustor. The distribution law of wall pressure is basically consistent with the experimental values, and the numerical agreement is good, indicating that the numerical simulation algorithm for the multi-GPU supersonic combustion chemical reaction established in this paper is correct and reliable. On the Tesla V100 GPU parallel computing platform, the speedup of GPU parallel computing can reach over 100 times, greatly improving computational efficiency. When the grid size is 18.64 million, the parallel efficiency of single and double precision floating-point operations on four GPUs is 66.2% and 69.1%, respectively, which demonstrates that the multi-GPU parallel algorithm has good scalability.
A time-fuel hybrid optimal guidance for micro/nano satellite’s glideslope approach
Authors: Zeng Nengwei , Xu Gen , Chen Danhe , Liu Xingchuan , Lu Zhengliang
Published: May 2024

Aimed at the trajectory planning problem of micro/nano satellites’ approaching missions under multiple constraints, this paper proposes a V-bar glideslope maneuver optimization method considering both time and fuel consumption. A dual-objective trajectory optimization model is established based on the CW motion equation, considering the constraints of trajectory and impulse. The optimal solution set of the glideslope point position and maneuvering time is obtained by employing the NSGA2 algorithm. In order to reduce computational complexity, a method for simplifying trajectory optimization is proposed. By solving a constrained dual-impulse optimization problem, the feasible range of distance and transfer time between adjacent glideslope points are obtained, which transforms the constraint equations of the glideslope maneuver optimization into the search space of optimization variables. The problem is simplified to an unconstrained optimization problem. Finally, a simulation is conducted with the approaching mission of a typical micro/nano satellite. The results demonstrate that the proposed method can provide an optimal solution set considering both fuel and time consumption, offering a flexible maneuver planning strategy for on-orbit application.
Experimental research on the atomization of transverse liquid jet
Authors: Fu Benshuai , Lu Bingju , Xiao Haiyan , Qin Liping , Li Guanghua
Published: May 2024

The transverse liquid jet is widely used in gas-steam ejection, scramjet engines, and other engineering applications. The research of transverse liquid jets can provide a basis for product design and has a wide range of engineering application value. A high-temperature and high-pressure jet experimental system was designed according to the characteristics of the cooling water jet atomization in the gas-steam ejection power system. The high-speed photography method was used to obtain the macroscopic structural characteristics of the transverse liquid jet. In this paper, experimental research of liquid jets under three conditions was carried out. The trajectory curve of the liquid jet considering momentum ratio and temperature is as follows: y/dj
= 2.782q
0.422(x/dj
)0.307(T/T0
)-0.785. It can provide theoretical support for improving the efficiency of gas-liquid mixing in power systems, engines, etc.
Analysis of landing gear simplified modeling and simulation based on amesim
Authors: Jia Junjie , Li Wei , Li Shengjun , Zhu Zhenshan , Ren Fang , Xie Yan
Published: May 2024

Aiming at the theoretical research of aircraft take-off and landing taxiing control characteristics and real-time interactive application scenarios, the simplified model modeling method of landing gear is studied. Through the reasonable simplification hypothesis of the landing gear pillar, a benchmarked, general, and pillar-type simplified model of the landing gear is formed. In the process of ground motion, based on the force analysis of aircraft taxiing, a six-degree-of-freedom mathematical model of ground taxiing is established. Based on the Amesim six-degree-of-freedom model, the aircraft is built, and the simulation test of aircraft taxiing turning and landing brake is carried out in combination with the simplified take-off and landing model. The results show that the general benchmarked pillar landing gear model formed in this paper is reasonable and feasible, and can quickly construct the aircraft landing gear model, which is convenient for subsequent optimization and design.
Fluid-solid-ablation coupled calculation of hypersonic vehicle based on rbf grid deformation method
Authors: Yang Fan , Dai Gang , Zhao Wenwen , Chen Lihua
Published: May 2024

The ablative phenomenon of the thermal protection system happens when the hypersonic vehicle suffers serious challenges of aerothermal due to high Mach number. To determine whether the thermal protection system is destroyed, the fluid-solid-ablation loosely coupled method for Carbon-Carbon composite materials is proposed to calculate the deformation of ablation and acquire the deformed shape. Navier-Stokes equation, heat conduction equation, and linear ablation model are applied to calculate the fluid field, the solid field, and the ablation receding amount. As one of the most widely applicable dynamic mesh methods, the Radial Basis Functions (RBF) dynamic method is used to get the deformed solid mesh. The ablation of a missile is computed and analyzed. It could be found that the surface temperature of the head increases during flight and the ablation of the surface results in the change of the vehicle’s shape. The ablative layer thickness of the thermal protection system should be greater than the max ablative deformation, reaching 4.4 mm of the missile. The proposed fluid-solid coupling method could effectively predict the ablation deformation of the vehicle and guide the design of hypersonic vehicle thermal protection systems.
Aircraft maintainability verification evaluation based on fuzzy analytic hierarchy process
Authors: Chen Xingxing , Feng Mingyu , Zhao Rujuan
Published: May 2024

This paper uses the fuzzy analytic hierarchy process to establish the mathematical model of aircraft maintainability verification in the flight test stage. The maintainability evaluation index system is constructed from the factors that affect the aircraft maintainability level, such as equipment layout and accessibility, cover design, marking and error prevention, standardization and interchangeability, and human factor engineering. Through case analysis, the application of this method in the maintainability verification of the military aircraft flight test phase is introduced.
Research on rapid batch test technology of small satellite attitude and orbit control system
Authors: Zhang Shaopo , Li Yongqiang , Dai Jianfeng , Wu Zhijing , Chen Ye
Published: May 2024

The attitude and orbit control sub-system of small satellites is an important sub-system to ensure the stable operation of satellites in orbit, and its testing in the satellite factory development stage runs through the whole testing process. Most of the traditional attitude and orbit control sub-system tests require the cooperation of many people to complete the performance tests of various components and sensitive devices, which also leads to the complicated and time-consuming testing process of the sub-system. At present, the mass production of small satellites is developing rapidly. In order to meet the urgent needs of small satellite mass production, the traditional attitude control subsystem test equipment and methods can’t meet the requirements of satellite mass production mode. In order to meet the needs of small satellite mass development, this paper studies the rapid batch test technology of small satellite attitude and orbit control systems. A fast pipeline test system which can support the performance and dynamics simulation of various components of a multi-satellite attitude and orbit control subsystem is studied. Based on the architecture of real-time communication between the upper computer and lower computer, the system can realize the integration and rapid testing of component performance and dynamic simulation. A continuous dynamic simulation test of 2140 seconds was carried out for the cruise mode and attitude maneuver mode of a certain type of satellite in orbit. During the test, various components and sensors of the attitude and orbit control subsystem operate correctly and can support the stable operation of the required attitude in various modes of the satellite, which can verify the correctness of the interface and performance of the satellite attitude and orbit control subsystem. The research results greatly reduce the input of manpower and material resources, and greatly improve the test efficiency. It lays a foundation for the rapid batch test of the small satellite attitude control subsystem.
A model-based control strategy for turbo-shaft engine
Authors: Xin Changkun , She Yunfeng , Xing Yaoren , Meng Sheng
Published: May 2024

This paper takes the turbo-shaft engine (the power source of the helicopter) as the research object, and mainly conducts the simulation of its related control law and control structure. The working principle of the turbo-shaft engine is briefly introduced initially, and then the component-level model of the turbo-shaft engine is established. This paper focuses on the design of the control law upon the turbo-shaft engine, and verifies the designed control law through the results of simulation by MATLAB/Simulink. Finally, the relevant data collected from 240KW hybrid system is taken into the consideration to verify the control algorithm. The results show that the control accuracy of the corresponding control algorithm in this paper is high (accuracy≤5%).
The active disturbance rejection control method for small-scale turbojet engine
Authors: Wang Nan , Xu Jianguo , Li Zixing
Published: May 2024

To enhance the disturbance resistance of the control system for a small-scale turbojet engine, research has been conducted on the active disturbance rejection control (ADRC) method. With gas generator speed N
g as the control parameter, an ADRC control scheme was established. Tracking Differentiator (TD), Nonlinear State Error Feedback (NLSEF), and Extended State Observer (ESO) were analyzed in detail, and their parameters were designed. The ADRC method was compared with the Expert PID control method through simulation experiments. The results show that ADRC has a small overshoot and strong disturbance rejection capabilities, allowing for a faster recovery to a steady state when disturbances occur.
A novel unloading strategy for solar sails using reflectivity control device
Authors: Qi Xuanchi , Fan Caizhi , He Guanwei
Published: May 2024

For near-Earth spacecraft, many environmental forces are utilized to unload reaction wheels. However, effects like magnetic force or atmospheric friction hardly exist in deep-space environments where solar sails operate. Thus, this paper proposes an unloading method that uses reflectivity control devices to generate Solar Radiation Pressure (SRP) torque to conduct the unloading process of solar sails operating in deep space. Firstly, the basic principles of the Reflectivity Control Device (RCD), satellite kinetic model, and Pulse Width Pulse Frequency (PWPF) modulator are given. Secondly, based on the torque envelope obtained by traversing all switch combinations of RCD, a novel strategy using a PWPF modulator is specially designed to achieve efficient unloading. In the end, we carry out numerical simulations and analyze the influence of different parameters, through which the validity of the proposed torque resolution scheme is demonstrated.
Guidance algorithm for reusable launch vehicle considering change in target
Authors: Huang Xinyu , Dai Jing , Liu Gang
Published: May 2024

To address the design challenges of reentry guidance for high-speed aircraft in complex environments, and in response to the need for target adjustments during reentry, a method for designing reentry guidance laws with extended range has been introduced. The longitudinal guidance law has significantly improved real-time performance by converting infinite-dimensional optimization into a single-parameter search using the reentry flight corridor approach. The lateral guidance law employs line-of-sight angular deviation corridors to achieve target tracking, while the extended-range guidance law rapidly increases the flight distance of the reusable launch vehicle during the flight by optimizing attack angle profiles. Numerical simulations have been conducted to validate the effectiveness of the longitudinal, lateral, and extended-range guidance laws, indicating that they can meet the mission requirements for target adjustments during reentry.
Reentry trajectory optimization of hypersonic glide vehicle based on improved particle swarm algorithm
Authors: Su Zili , Zhao Jisong , Liu Jiaolong
Published: May 2024

The reentry process of hypersonic glide vehicle presents a host of intricate constraint issues. A method for optimizing the reentry trajectory of hypersonic glide vehicle is presented to achieve the shortest possible reentry time. The approach utilizes the improved particle swarm optimization (IPSO) algorithm. Firstly, population initialization is performed using the quasi-oppositional differential evolution (QODE) strategy to promote diversity within the population. Then an adaptive adjustment algorithm is designed for the inertia weight coefficient and learning factor to achieve a balance between global and local search capabilities. Finally, utilizing the IPSO algorithm for optimizing the flight parameters of the reentry trajectory, the reentry time is reduced from 338 seconds to 335 seconds. The simulations results indicate that the IPSO algorithm outperforms both the standard PSO algorithm and genetic algorithm (GA) in terms of optimization performance index.
Investigation on the growth behaviour of creep crack in 2219 aluminium alloy by nanometre computed tomography
Authors: Fu Kang , Zuo Xin , Zheng Ying , Shi Jianghuan , Guo Qi , Tang Shengming
Published: May 2024

Aluminium alloy is widely utilized in aerospace engineering because of its lightweight and high specific strength. Creep and fracture of aluminium alloy serving at high-temperature conditions are always a long-term concern. Especially creep crack nucleation and growth behaviours under high out-of-plane constraint levels are the significant processes to generate failure. High-resolution nanometre computed tomography equipment can be adopted for obtaining the three-dimensional morphology and information on damage to investigate the mechanism of creep crack growth. According to the obtained results, the stress-field strength has an impact on creep crack propagation under high out-of-plane constraint levels.
Air tightness detection method in parallel for aerospace: mechanical design, system modeling and optimum control
Authors: Yang Bo , Yuan Jianhui , Wang Xiaoliang , Zhang Jianwei , Wu Wei , Xie Mingyang
Published: May 2024

To address the problems of high cost, complex operation, and low efficiency of existing equipment for aerospace, a simple but efficient multichannel air tightness detection device is designed. A physical system model is constructed for the process of inflation, deflation, and inflation with leakage. The expression between the inflation/deflation rate and the valve area is obtained. Through modeling the intersection and rotation of spatial curves, the relationship between the valve area and the valve core angle is derived, and the optimal valve core angle calculation method is proposed to achieve precise rate control of inflation and deflation. Simulation experiments and numerical analysis demonstrate the superiority of the proposed system scheme, the effectiveness of the control method, as well as the accuracy of the mathematical model. For the tested object of 0.3 L, the target pressure of 400 KPa, and the inflation and deflation rate of 75 Kpa/min, by using four channels with a 10 s interval for sequential operation and adjusting valves every 60 s, the efficiency of inflation and deflation is more than 3.5 times that of a single device with a single circuit. Its performance is not much different from real-time automatic control equipment, but the economy is greatly improved.
Analysis of internal pressure and vibration of a flexible expansion ratio elongation nozzle shape
Authors: Zeng Yi , Huang Wei , Xu Jingsheng , Guo Zongtao , Ren Xiaobin
Published: May 2024

The nozzle made of flexible materials can expand and elongate its profile at different flight altitudes, greatly improving the engine’s endurance and ballistic accuracy. However, this also introduces the problem of structural vibration in the nozzle, which adversely affects engine performance. This paper introduces a high-precision hyperelastic material constitutive model for the flexible elongation nozzle and uses numerical simulation to conduct a detailed analysis of the internal pressure and structural vibration under aerodynamic pressure loads. As the flight altitude increases, the pressure magnitude and distribution on the inner wall of the same elongated flexible expansion section do not change. The pressure distribution on the inner wall of the flexible elongation expansion section exhibits certain nonlinear characteristics, and its magnitude decreases gradually along the axial position. The vibration of the elongated expansion nozzle profile becomes more intense with the increase in flight altitude. At high characteristic flight altitudes, the elongation length of the longer expansion section approaches an undamped vibration state.
Orbital constraints and efficiency modeling for calibration satellites in long-range radar applications
Authors: Sun Changjun , Li Yaoyao , Dong Ping
Published: May 2024

Orbit design is a critical aspect of the calibration satellite system, with its effective configuration being integral for successful satellite calibration. This paper addresses the challenge of designing satellite orbits while considering the constraints imposed by satellite-ground equipment performance and launch capabilities. Key factors constraining calibration satellite orbits are analyzed, and orbital constraint equations are developed, focusing on radar performance, calibration time, and regional coverage. The study also introduces a model to assess the efficiency of satellite orbits for calibration purposes, which is rigorously validated through simulation. This study uniquely addresses the integration of radar performance with satellite orbit design, an area not extensively explored in current literature.
Preliminary results for platform testing of ASO-S satellite
Authors: Zhu Cheng , Yin Zengshan , Deng Lei , Bao Haichao , Cao Caixia , Jiang Hu , Chen Binglong , Zhang Ye , Li Xinyu , Liu Kuo , Yang Zhongguang , Yang Yong , He Tao , Bai Yanping , Xu Yibo , Zhu Yunfei , Wang Shouliang
Published: May 2024

Advanced space-based solar observatory, which is short for ASO-S, was successfully launched by Chinese launcher CZ-2D in Oct. 2022. As of Dec. 13, 2022, the platform testing of the ASO-S satellite finished. The platform consists of seven main subsystems. The nominal specifications for every subsystem are laid out in detail in its technical document. The nominal specifications are used as a baseline to judge whether the in-orbit testing results are acceptable. The preliminary results include measurements for every specification for platform testing of the ASO-S satellite. The data analyses have shown that the performance of the main subsystems of the platform has Satisfied the specifications required by the technical documents. The platform performance has been demonstrated to be completely acceptable. The healthy platform performance of ASO-S will further support the payloads of the satellite in carrying out in-orbit observations of Solar activities.
Research on electronics hardening technology of integrated electronic system of lunar exploration Cubesat
Authors: Wu Tao , Zhang Wen , Zhou Yang , Wang Chong , Ao Liang , Cao Suzhi
Published: May 2024

In the lunar exploration CubeSat mission, the complex space environment and limited onboard resources place higher requirements on the anti-radiation design of the integrated electronic system. By analyzing the destructive effects of the deep space radiation environment and the failure mechanism of components, a hardening scheme for the integrated electronic system of lunar exploration CubeSat is proposed. A variety of measures are taken to target the key components and circuit parts in the integrated electronic system that are susceptible to radiation damage. A prototype verification system for anti-radiation hardening technology was designed and system-level testing was carried out. Research results show that adopting effective radiation-resistant hardening technology can significantly improve the safety and reliability of CubeSat integrated electronic systems in deep space environments.
High time effective detection strategy for geosynchronous orbital space debris
Authors: Zhang Hongbo , Wang Ke , Shang Xiaoyu
Published: May 2024

After the formation of a multi-satellite network in a hypersynchronous orbit, it has the ability to continuously and in real-time observe the GEO band, which is an ideal way to solve blind spots and semi-backlight observations and improve the system’s high time-effective coverage ability. In response to the application limitations of high-orbit real-time monitoring constellations in hypersynchronous orbits, such as the large number of satellites in the network, high requirements for satellite detection capability, large field of view, and high launch and orbit cost, this paper proposes a constellation system efficiency analysis method that comprehensively covers both time and space dimensions. Based on this, optimization analysis of satellite detection capability, detection field of view, number of satellites, and orbit height is carried out. Finally, three constellation optimization schemes are provided, which are a semi-major axis of 60000 km with seven satellites, a semi-major axis of 55000 km with eight satellites, and a semi-major axis of 50000 km with ten satellites. The three constellation optimization schemes can provide a reference for the development of space-based high-orbit situational awareness in the future.
Intelligent mission planning of sky survey based on the NSGA-III algorithm
Authors: Jia Rongsheng , Wang Hongfei
Published: May 2024

In recent years, China has been scheduled to launch an all-sky survey telescope for celestial observation. The meticulous arrangement of observation sequences for this telescope is of paramount importance, given the myriad challenges and constraints inherent to such astronomical survey missions. These challenges encompass factors such as spatial limitations, stray light contamination, as well as constraints related to data storage and energy consumption. This undertaking presents a quintessential NP-hard optimization problem. To address this complexity and enhance in-orbit observation efficiency, this study closely adheres to practical engineering considerations. A comprehensive evaluation of diverse constraints is conducted, culminating in the establishment of an optimization model for systematic planning of sky survey missions. The primary optimization objectives encompass maximizing in-orbit observation duration, augmenting the count of observable celestial points, and minimizing maneuvering angles. To tackle this multifaceted problem, a mission planning algorithm is devised based on NSGA-III, a multi-objective optimization technique. The experimental results indicate that the sky survey planning algorithm proposed in this paper can effectively accomplish sky survey observation tasks, achieving the scientific objective of no fewer than 350 daily observation points. It holds the potential to provide algorithmic support for the sky survey telescope mission on the Chinese space station.
A GNU radio-based design for GPS software simulation source
Authors: Lin Yang , Yuan Jiangnan , Wang Guangyi , Shen Mingliang
Published: May 2024

GPS (Global Positioning System) plays a crucial role in modern navigation and positioning applications. Traditional research and development of GPS signals require expensive hardware equipment, limiting the flexibility and scalability of the system. In this paper, an open-source software called GNU Radio is utilized to construct a GPS signal simulation system, leveraging its rich modules and signal processing libraries. The GPS baseband signals are generated using signal processing modules provided by GNU Radio. Appropriate noise and interference are added to simulate the signal characteristics in real-world environments. Both single-channel and multi-channel signal models are presented. By comparing the generated GPS signals with those from hardware-based simulators, the results demonstrate that the GPS software simulator based on GNU Radio can produce high-quality GPS signals with excellent flexibility and adjustability.
Analysis of the mechanical response of solid rocket engine propellant under acceleration shock
Authors: Shangguan Zihan , Zheng Jian , Sun Liangcheng
Published: May 2024

The increased-range solid rocket engine of new ammunition often needs to withstand extremely high acceleration overload, leading to damage to the propellant’s structural integrity. To address this issue, this paper constructs a nonlinear viscoelastic constitutive model for the CMDB propellant by using low- and high-strain rate mechanical property tests. Combined with the secondary development of explicit dynamics and numerical simulation technology, the mechanical response of a certain type of solid rocket propellant under different acceleration impacts is analyzed. The results show that under acceleration impact loads, the propellant will compress, rebound, and recover over time, continuously cycling. Its axial displacement, maximum equivalent stress, and maximum equivalent strain exhibit irregular sinusoidal wave-like periodic cycles. Looking at the time when the peaks appear, the time when the maximum equivalent stress appears always lags behind the time when the maximum axial displacement peak appears. Due to the viscous effect of the viscoelastic material of the propellant, the time when the equivalent strain peak appears will lag behind the equivalent stress. Because of the material’s damping effect, both the peak values of the maximum equivalent stress and equivalent strain decrease over time. Under continuous high acceleration impact loads, this viscous damping phenomenon continuously diminishes, and the peak value of the propellant’s axial displacement gradually increases.
The effect of the stress equilibrium factor on the composite case of the solid rocket motor
Authors: Li Jing , Zhou Changsheng
Published: May 2024

In this paper, based on the composite structure design and analysis software ANSYS ACP, the layup design for the composite cases of the equal pole hole solid rocket motor with different stress equilibrium factors is carried out. The finite element software ANSYS Workbench is used to study in detail the effects of stress equilibrium factor on the stress level, failure degree, and burst pressure prediction of the case under a certain internal pressure. The results show that reducing the value of the stress equilibrium factor can reduce the stress level of each winding layer along the main direction of the material in the motor case and gradually transfer the maximum stress of the case along the fiber direction from the weak stress zone to the cylinder section. This is beneficial for improving the burst pressure of the case and making the burst point located in the cylinder section. However, whether the case failure is related to the selected failure theory and strength criterion, the failure results and burst pressure obtained using different failure theories and strength criteria may be different, which indicates that each failure criterion has its scope of application and limitations. Under the Tsai-Wu criterion, using the stress equilibrium equation to calculate the stress equilibrium factor can just ensure that each winding layer of the motor case does not fail under the working pressure. In summary, when designing a composite case and predicting its failure, in addition to considering whether the stress equilibrium factor taken is conducive to meeting the design requirements for the strength of the case, it is also necessary to consider the use of multiple failure criteria to study the failure of the case. Obviously, arbitrarily selecting the stress equilibrium factor is not appropriate in the above process. By analyzing the influence of the stress equilibrium factor on the strength and failure condition of the motor case, it can provide an effective reference for the design of a composite case for SRM.
Measurements of time resolution of the RD50-MPW2 DMAPS prototype using TCT and 90Sr
Authors: Debevc J. , Franks M. , Hiti B. , Kraemer U. , Kramberger G. , Mandić I. , Marco-Hernández R. , Nobels D.J.L. , Powell S. , Sonneveld J. , Steininger H. , Tsolanta C. , Vilella E. , Zhang C.
Published: May 2024

Results in this paper present an in-depth study of time
resolution for active pixels of the RD50-MPW2 prototype CMOS
particle detector. Measurement techniques employed include Backside-
and Edge-TCT configurations, in addition to electrons from a
 90Sr source. A sample irradiated to
5 · 1014 neq/cm2 was used
to study the effect of radiation damage. Timing performance was
evaluated for the entire pixel matrix and with positional
sensitivity within individual pixels as a function of the deposited
charge. Time resolution obtained with TCT is seen to be uniform
throughout the pixel's central region with approx. 220 ps at
12 ke- of deposited charge, degrading at the edges and
lower values of deposited charge. 90Sr measurements
show a slightly worse time resolution as a result of delayed events
coming from the peripheral areas of the pixel.
Multiscale slope analysis and functional correlation with gloss reflectance from photographic papers
Authors: Bartkowiak Tomasz , Etievant David , Brown Christopher A
Published: May 2024

A novel multiscale 3D topographic characterization for slope is introduced. Slope is considered as a crucial parameter linking area-scale and 3D curvature analyses. Relationships between surface topography and gloss reflectance in photographic papers are used for an example application. Directional angles, characterizing slopes, are calculated two ways: normals to triangular facets (method 1), and eigenvectors of a covariance matrix based on nine points (method 2). Slope is the steepness of surface inclinations associated with the orientation of local surface features (facets). The impact of slope on gloss reflectance supports the use of pertinent geometric characterizations, i.e., alignment of geometric characterizations with the physical nature of the topographic interaction phenomena. Topographies of 24 photographic papers, were measured with a laser scanning confocal microscope and their gloss reflectance was measured with a micro-TRI-gloss gloss meter. Analyses of slope distributions with bivariate dispersion measures of directional angles and their trigonometric functions revealed strong correlations (R2 > 0.6) between slope distributions and gloss. Bivariate median deviation of secant or tangent of directional angles, demonstrated consistently high correlations across scales, magnifications, and filtrations. This study supports pertinent and useful characterizations grounded in the physics of topographic interaction phenomena to provide insights into relationships between surface topography, e.g., slope and gloss reflectance in photographic papers. This nuanced understanding has potential applications for other applications as well.
Integrated form-position measurement of large-aperture transparent elements based on stereoscopic phase measuring deflectometry
Authors: Chen Ting , Yang Peide , Lang Wei , Chen Yunuo , Wang Wei , Zhang Xiangchao
Published: May 2024

In the field of ultra-precision manufacturing and measurement, sub-aperture stitching is a widely employed technique for the measurement of complex optical components. Those influencing factors like system errors and numerical bias introduce notable stitching errors in the overlapped areas between sub-apertures, consequently degrading measurement accuracy. In addition, the surfaces forms, refractive indices, and positions are difficult to be specified simultaneously. In this paper, an integrated measurement method based on the stereo deflectometry is proposed, which can measure the surface form, refractive index, and relative position of large-aperture transparent components together. This method utilizes a Gaussian process regression model to decouple and predict the refractive index and relative positions of the upper and lower surfaces. Then, a robust sub-aperture stitching technique with an adaptive distance function is employed to correct the positioning errors of sub-apertures. The feasibility and effectiveness of this method are demonstrated. The final stitched surface results exhibit a measurement error of 320 nm and a thickness deviation of 28 μm.
Bioactive compounds-loaded polyvinyl alcohol hydrogels: advancements in smart delivery media for biomedical applications
Authors: Luthfianti Halida Rahmi , Waresindo William Xaveriano , Edikresnha Dhewa , Hapidin Dian Ahmad , Noor Fatimah Arofiati , Elfahmi Elfahmi , Khairurrijal Khairurrijal
Published: May 2024

The paper initially focuses on the characteristics of Polyvinyl Alcohol (PVA) hydrogel as smart delivery media, such as chemical stability, biocompatibility, and capacity for controlled release of bioactive compounds. Then, it discusses the effect of loading bioactive compounds into PVA hydrogel, considering their stability of delivery media, controlled release, and targeted delivery, enhancing therapeutic outcomes. Loading bioactive compounds such as diphlorethohydroxycarmalol (DPHC), curcumin, carotenoids, andrographolide, and flavonoids into PVA hydrogels can enhance biomedical functionalities. These functionalities include improved drug delivery, wound dressing efficacy, tissue engineering potential, and contact lens applications. Further, while previous review papers have extensively covered aspects such as the source of bioactive compounds, extraction methods, synthesis of PVA hydrogel, and various biomedical applications, there remains a gap in the literature in which no studies have systematically explored the loading of bioactive compounds into PVA hydrogel. This targeted investigation distinguishes our work from previous studies and contributes a novel perspective to the expanding hydrogel market. In light of the projected compound annual growth rate of 7.15% in the hydrogel market from 2021 to 2028, this study provides a pioneering overview of recent advancements in bioactive compound-loaded PVA hydrogels. Finally, this review outlines the challenges in optimizing bioactive compound-loaded PVA hydrogels’ performance and their biomedical application. In the future direction, this review explores their potential in smart delivery media, such as optimizing the loading efficiency and releasing kinetics to specific target therapeutic, crosslinking with double or triple network hydrogels, and convergence of nanotechnology with hydrogel that become frontiers in precision medicine.
The Political Theology of Salomon Maimon
Authors: Melamed Yitzhak Y
Published: May 2024

The terminology of ‘political theology’ is not original to the twentieth century. Salomon Maimon (1753–1800) used the term as part of the title to a chapter of his 1792/3 Autobiography, and it is the primary aim of this chapter to explain his understanding of it. The chapter begins by exploring the notion and Salomon Maimon’s account of the role of secrets in religious matters. Next, it studies Maimon’s definitions of, and distinctions among, various forms of religion. Finally, it outlines Maimon’s views on “the greatest of all the mysteries of the Jewish religion” and on the nature of that religion.
“To separate faith from philosophy”
Authors: Shapshay Sandra , Auweele Dennis Vanden
Published: May 2024

Surveying Schopenhauer’s published work attests to a profound engagement with Spinoza. Most references that make it into his published work are to Spinoza’s Ethics and usually concern the philosophical problem of individuation, but it would be hasty to conclude that Schopenhauer does not enter into philosophical debate with Spinoza on the material of the Theological-Political Treatise. In fact, there are some uncanny similarities and telling differences between that work and Schopenhauer’s own philosophy of religion, which he develops throughout his published works but most comprehensively in his ‘On Humanity’s Metaphysical Need’ (1844). This chapter concentrates mostly on what we see as the implicit dialogue that Schopenhauer is having with Spinoza. It argues that the differences in their ways of appreciating religion derive from different ways of doing metaphysics, which, further, cast light on why Schopenhauer believes he has “much more right” than Spinoza “to call [his] metaphysics an ethics.”
A View of a View of the Good
Authors: Shields Christopher
Published: May 2024

Plato defends a distinctive account of goodness, given in terms of his Form of the Good. This Form, he thinks, is univocal, common to all good things, a universal and a paradigm, existing independently of its being realized. Aristotle denies several of these characterizations, but has a special animus against Plato’s commitment to the univocity offered by the Form of the Good. In his Nicomachean Ethics i 6 (and in a partially parallel discussion in his Eudemian Ethics i 8), Aristotle develops and deploys a litany of arguments against Plato’s commitment to univocity. Some of these arguments appeal to Aristotle’s own theory of categories and others do not. All raise significant challenges to Plato’s axiology: Aristotle contends in a host of different ways that Plato fails to appreciate the complexity of value exhibits across distinct domains.
A Series of Goods
Authors: Shields Christopher
Published: May 2024

Aristotle’s first argument against Plato’s Form of the Good is compressed in the extreme. He argues: (i) there are no Forms, as even the Platonists allow, set over items, like numbers, arrayed in a series; (ii) good things form a series; so, (iii) there is no Form of the Good. Each of these premisses is obscure and requires careful expansion. None of four attempts at explaining or justifying (i) succeeds. Further, (ii) seems either ill-motivated or to rest on categorial considerations in a way rendering this argument incomplete. Even so, Aristotle’s criticism raises important questions about the Form of the Good.
Goodness across the Categories
Authors: Shields Christopher
Published: May 2024

Aristotle’s premier argument against Plato’s commitment to the univocity of goodness is clearly his categorial argument. It is difficult to say, however, precisely what this argument is: it has been subject to a wide range of interpretations and concomitant critical assessments. This chapter examines the most significant of the many interpretations of this argument on offer: it focusses especially on predicational and non-predicational approaches and reconsiders the relevance Peter Geach’s approach to goodness to Aristotle’s categorial argument. These explorations, together with a careful, textually sensitive reconstruction of Aristotle’s argument, permit us to come to a clean interpretation, which in turn provides a basis for a fair-minded, neutral assessment.
Adding ‘Itself’
Authors: Shields Christopher
Published: May 2024

Aristotle takes aim at what he takes to be an indefensible Platonic indulgence, the supposition that by adding ‘itself’ to some term T, we arrive at a Form of T, ‘the T-Itself’. So, for instance, if we think that some people exhibit courage, we can focus on their courage and begin speaking of ‘Courage Itself’, thereby positing a Form of Courage. Aristotle objects to this entire procedure. Is this, though, Plato’s actual method? It seems unlikely that Plato would presume that a simple linguistic transformation would yield a Form, however; and, upon deeper inspection we find that Aristotle, too, adds ‘itself’ as a sort of intrinsicality filter intended to isolate a predicate. Isolating predicates in this way, however, hardly vouchsafes their univocity.
Intrinsic Goods Alone: A Platonic Rejoinder
Authors: Shields Christopher
Published: May 2024

Aristotle pauses in the midst of his criticisms and rather gamely offers Plato an out: perhaps there is a Form of the Good set over all and only things which qualify as intrinsically good, as good in their own right, or as good per se. Careful attention to even this limited range of good things, however, reveals non-univocity even here. So, again, he concludes, there is no Form of the Good. This interlude in the text, though, has two striking consequences. First, in responding, Aristotle embraces a remarkably fine-grained form of non-univocity. Second, in so doing Aristotle incurs and acknowledges a commitment to determine how good things are related short of univocity.