bluuebunny/crossref_metadata_2025_split huggingface dataset:
Large angle attitude control of cubesat based on multi-objective optimization
Authors: Xu Shuo , Liao Wenhe 
Published: August 2024

Abstract
The rigid body motion of CubeSat is strongly coupled with the elastic vibration of the flexible structure during the large angle attitude maneuver of the CubeSat. The drastic change of attitude will aggravate the jitter of the solar panel, which will then disrupt its stability. To deal with the contradictions between the rapidity and high-precision stability of large angle attitude maneuver of CubeSats and ensure the higher attitude pointing accuracy of the satellite after the attitude maneuver, this paper presents a multi-objective optimization algorithm based on the quintic polynomial path. This optimization algorithm can reduce the angular velocity as much as possible and obtain the optimal solution of maneuvering time. Then, a terminal sliding mode finite-time controller developed from a nonlinear disturbance observer is proposed. The nonlinear disturbance observer can calculate the disturbance, and the terminal sliding mode finite-time controller can perform feedforward compensation to improve the anti-interference ability of the control system, to achieve the desired finite-time attitude tracking control. Finally, a digital simulation platform based on the momentum wheel and magnetic torque is built. Experimental results show that the quintic polynomial path based on the multi-objective optimization algorithm can effectively reduce the angular velocity during attitude maneuver, and achieve the optimal time solution. The finite-time controller can effectively track the optimal path and ensure the rapidity and stability of attitude maneuvers.
Safety distance analysis for high-speed railway platforms using fluid dynamics and mathematical modeling.
Authors: Liu Jiacheng , Jin Yuxuan , Lv Hanmin , Ding Qirui 
Published: August 2024

Abstract
This paper introduces a model based on Bernoulli’s equation, Dubois’s body surface area calculation method, and Newton’s second law to determine safety markings on high-speed railway platforms. The J coefficient is proposed to calculate net force and safety distance coefficient, resulting in positive ratio coefficients of weight to net force, volume to net force, and inverse ratio coefficients of distance to net force. ANSYS FLUENT software is used for computational fluid dynamics simulations to analyze the impact of different factors on safety marking installation. Recommendations are made based on the findings to improve the safety of station platforms.
End-to-end control of quadrotor based on preference learning
Authors: Shen Qiguang , Zhang Shoufeng , Wu Zhaobin 
Published: August 2024

Abstract
The highly coupled, underactuated, and nonlinear characteristics of quadrotors make it difficult to meet the need for efficient and stable control performance in unknown dynamic environments through the method of modeling and designing controllers. Reinforcement learning allows learning on the base of the controlled object model, updating and optimizing the control strategy with data generated from interactions with the environment, providing a new solution to this problem. However, conveying complex objectives to quadrotors is often challenging, involving the design of reward functions that need to provide sufficient information. Imitation learning can teach agents interactively by learning prior knowledge, but it also faces problems such as the difficulty of acquiring prior knowledge. In this work, our goal is to bypass the design of reward functions and improve the generalizability of quadrotors in different tasks. Specifically, we score the trajectories generated by quadrotors, learn the reward model based on preferences between different trajectories, and use it to train the quadrotors. We can demonstrate that using reward models fitted according to trajectory preferences and directly defining reward functions yields consistent results, maintaining satisfactory learning rates and performance in both “velocity_control” and “hovering_control” tasks.
Identification of turbofan engine state-space model based on flight test data
Authors: Liu Yi 
Published: August 2024

Abstract
The experimental data recorded during flight tests contain rich system dynamic information, which makes it possible to use flight test data for system model identification. Engine state-space model identification based on flight test data can establish an accurate mathematical model of the engine, providing essential support for the design of multivariable engine control systems, engine health monitoring, and fault diagnosis. In this paper, based on engine flight test data, the least squares method is used to identify the state-space model of a certain type of large bypass ratio turbofan engine.
Research and analysis on the rotation of high-voltage electric propulsion harnesses under low temperatures and complex trajectories
Authors: Li Zongliang , Zhao Jingchao , Liu Yizhuo , Song Fei , Li Zhong , Yu Haixiang 
Published: August 2024

Abstract
Spacecraft use electric propulsion to complete tasks such as position maintenance and orbit makeovers, requiring vector adjustment mechanisms to minimize the deviation between the thrust vector of the electric thruster and the spacecraft’s centre of mass. The harness provides high-voltage power to the electric thruster and needs to be coiled and rotated on the thrust vector adjustment mechanism. The bending torque of the high-voltage harness is one of the main factors that need to be considered in the design of the driving capacity of the vector adjustment mechanism. This article proposes a reliable rotation evaluation scheme for high-voltage harnesses in low-temperature environments and complex trajectories. The verification of high-voltage harness torsion times under a wide range of temperatures (-110°C~+150°C), two-dimensional rotation angles (A-axis −18°~+18°, B-axis −25°~+59°), and bending torque tests for high-voltage harness under temperature range combinations (-110°C~+150°C) have been completed. The analysis data shows that the bending torque of a high-voltage harness is monotonically related to the rotation angle and temperature and will increase with the increase of rotation angle and the decrease of temperature. The bending torque of a high-voltage harness is within the driving capacity range of the vector adjustment mechanism motor and can meet the requirements of task applications.
Adsorption mechanism of octadecylamine on inner surface of steam generator feed water pipe of pressurized water reactor nuclear power plant
Authors: Canshuai Liu , Di Wu , Guocai Xi , Fuzhi Zhou , Zhaohui Tian 
Published: August 2024

Abstract
In this paper, the Max Flow software is used to simulate the adsorption process of octadecylamine on carbon steel surface. The adsorption model of octadecylamine on metal interface is established and the adsorption structure is calculated layer by layer. Then, the stable adsorption configuration and the adsorption free energy is calculated. The main conclusions are as follows: 1) Physical adsorption of octadecylamine executes on the surface of carbon steel instead of chemical adsorption, and the adsorption layers increases with octadecylamine concentration. 2) Primary adsorption energy of octadecylamine molecule on the carbon steel surface is mainly provided by van der Waals force. 3) Adsorption layer stacking and operation temperature elevation weaken the spontaneous adsorption trend of octadecylamine molecules.
Progress in the study of corrosion characteristics of water-wall tubes of power station boilers by Cl−/SO4
2-
Authors: Yang H , Zhu Z P , Zhou S M , Li T 
Published: August 2024

Abstract
The higher the unit parameters, the more sensitive water-wall tubes are to the impurity ions in the feed water, especially when the feed water contains aggressive ions such as Cl−, SO4
2-, etc., which often cause severe corrosion to equipment. A great deal of research has been carried out to understand the characteristics of power plant boiler water wall tubes corroded by Cl−/SO4
2-, which is essential to keep industrial boilers running and power stations safe.In this paper, the author firstly elaborates on the furnace water treatment condition and the source of Cl−/SO4
2- in power plant furnace water; then, the development of water-wall tubes of the power plant corrosion study in Cl−/SO4
2- solution is summarized and discussed.
Effect of pre-filming potential on the electrochemical characteristics of 2205 duplex stainless steel in NaCl solution
Authors: Wang L. , Liu Zijian , Chen Xu , Li Renjie , Xie Yujun 
Published: August 2024

Abstract
The effects of pre-filming potential on the electrochemical characteristics and structure of the passivation film of 2205 duplex stainless steel (DSS) in 3.5% NaCl solution were investigated by electrochemical technology and XPS methods. The results showed that when the pre-filming potentials were 0.1 and 0.6 V, the formation process of passivation film was first porous and then dense. However, when the potential rose to 0.9 V, the passivation film eventually underwent an additional porous process. The passivation films pre-formed at different potentials were all bilayer structures. The passivation film of 2205DSS was composed of an inner rich-Cr oxide and an outer rich-Fe oxide. When the pre-filming potential was 0.9 V, FeOOH appeared in the iron-rich oxide layer. The semiconductor properties of the passivation film were independent of the pre-filming potential. With the increase in pre-filming potential, the diffusion coefficient and diffusion flux of the cation vacancies increased, and the migration of cationic vacancies in passivation films became easier.
Ciphertext only attack on QR code optical encryption system with spatially incoherent illumination using a neural network
Authors: Rymov D A , Shifrina A V , Cheremkhin P A , Ovchinnikov A S , Krasnov V V , Starikov R S 
Published: August 2024

Abstract
Optical encryption methods attract a lot of attention owing to their high encryption speed and bandwidth. Recently, neural networks (NNs) have been used for cryptanalysis of optical encryption techniques. In this paper, we for the first time to our knowledge applied a NN for ciphertext only attack on an optical encryption system with spatially incoherent illumination. A NN was used to extract encryption keys from ciphertexts, which can be used to decrypt the plaintext QR codes. Additionally, an optically encrypted QR code was successfully decoded after using the key extracted by the trained NN, that has been processed to account for discrepancies between the numerical model and the optical setup. The results show the vulnerability of the existing optical encryption system with incoherent light to attacks of this type, which indicates the need for improved optical encryption security.
Simple precipitation synthesis and solar light-driven photocatalytic degradation of Ag3PO4 floating photocatalysts
Authors: Bui Thi Thu Hien , Nguyen Pham Tran Anh , Vu Thanh Mai , Tran Thi Huong Giang , Tran Thi Kim Chi , Tran Thi Thuong Huyen 
Published: August 2024

Abstract
A highly efficient and stable photocatalyst, Ag3PO4, was prepared using a simple co-precipitation method at room temperature. The precursors used in this process were AgNO3 and K2HPO4. The resulting Ag3PO4 photocatalyst forms irregularly-shaped spheres with diameters ranging from 300 to 1 μm. The shape of the Ag3PO4 photocatalyst slightly changes when different surfactants (PVA, PVP, PEG) are used. The powdered Ag3PO4 photocatalyst exhibits excellent visible light-driven photocatalytic performance. It is capable of decomposing rhodamine B (RhB) as a model pollutant in just 5 min under visible light irradiation. This performance is quite remarkable. Interestingly, Ag3PO4 floating composite sheets have been achieved using polystyrene (PS) and fumed silica Aerosil 200. After three cycles, the decolorization of RhB dyes remains at 87% with the 30% Ag3PO4@PS/Aerosil 200 sheet. This indicates that the Ag3PO4@PS/Aerosil 200 photocatalyst is highly reusable and stable.
Frost-resistance prediction model for stress-damaged lightweight aggregate concrete based on BPNN: a comparative study
Authors: Fu Chun , Zhang Qiushi 
Published: August 2024

Abstract
With the depletion of natural resources and the requirement of higher strength-weight ratio, lightweight aggregate concrete has attracted more and more attention because of its good thermal properties, fire resistance and seismic performance. However, exposure to low temperature environments accelerates deterioration of concrete, thereby, reduce the service life of lightweight aggregate concrete. Even worse, in cold and arid regions, lightweight aggregate concrete often experiences accidental impacts, wind erosion, earthquakes, and other disasters during service, these damage significantly impact its frost-resistance. Therefore, accurately and quantitatively describing and predicting the frost-resistance of lightweight aggregate concrete under specific disaster conditions is crucial. In this study, take the initial damage degree and freeze-thaw cycles as input variables, while the relative dynamic elastic modulus (RDEM) as an out variable, a frost resistance prediction models for stress-damaged lightweight aggregate concrete was established based on back propagation neural network (BPNN). The results show that the predicted values of BPNN model are in good agreement with the experimental values, and the results are also compared with the revised Loland model which is proposed by another author. Results demonstrate that the average relative error between predicted values of BPNN and experimental values is only 1.69%, whereas the one of revised Loland model is 9.13%, which indicating that the proposed BPNN prediction model can achieve a relatively accurate quantitative assessment of frost-resistance throughout the entire post-disaster lifecycle of lightweight aggregate concrete, it also broadened the idea and provided a reference for the frost resistance prediction of stress-damaged lightweight aggregate concrete.
The effect of ion implantation dose on the friction and corrosion performance of titanium-coated magnesium alloy
Authors: DOU Zhongyu , Luo Shupeng , Zhang Dianxi 
Published: August 2024

Abstract
To enhance the performance of titanium plated coating on the surface of magnesium alloy AZ31, this study investigates the influence of N ion implantation dose on the structure, mechanical properties, and friction corrosion behavior of Ti film. The results reveal that N ion implantation leads to the formation of a new physical phase TiN and induces surface softening. However, with an increase in N ion implantation dose, microhardness of the Ti film increases due to the formation of TiN which enhances its hardness. Friction and wear experiments demonstrate that at maximum implantation dose, the coating exhibits minimal friction coefficient; however, an implantation dose of 5 × 1015 ion cm−2 offers superior wear resistance. The electrochemical test results indicate the corrosion current density and self-corrosion potential of Ti coating decrease with the increase of implantation dose due to the formation of nitride and the presence of N element, and corrosion resistance of the modified coating has been significantly enhanced. The research results provide reference for improving the protection performance of Ti coating on magnesium alloy surface.
Preparation and properties of ultra-high performance concrete incorporation multi-mineral admixtures
Authors: Zhao Wenhua , Kong Jiahui , Sun Qi 
Published: August 2024

Abstract
The impact of multi-mineral admixtures on the sturdiness of ultra-high performance concrete (UHPC). In this study on the premise that multi-mineral admixtures can be utilized in UHPC, we optimized the percentage of three admixtures(limestone powder,slag, and pumice powder) that can replace cement using the Box-Behken design response surface method, and prepared UHPC specimens with multi-mineral admixtures. The rationality of the multi-mineral admixtures approach proposed in this study was confirmed by characterizing the mechanical properties and porosity of the prepared specimens. Durability was also investigated through relevant tests. The results showed that the porosity of the prepared UHPC decreased by 49.4%, the mechanical properties improved by 14.7%, the self-shrinkage and drying shrinkage decreased by 9.8% and 6.2%, respectively, and the volume stability improved. Moreover the resistance to sulfate dry-wet cycling, chloride ion permeation, and carbonization improved significantly. This study, thus, demonstrates a new type of multi-mineral admixture for UHPC with excellent mechanical properties and durability.
Numerical simulation study on solidification proceoss of titanium slab ingot by electron beam cold hearth melting
Authors: Cao Wei , Ma Chong , Li Yang , Gao Lei , Chen Guo , Omran Mamdouh 
Published: August 2024

Abstract
Titanium and titanium alloys are key basic support materials in the field of engineering technology and high technology, and are widely used in the fields of natural gas transportation, chemical corrosion, and marine development. Titanium alloy ingots are often prepared with more solidification defects such as surface cracks and cold shuts, resulting in lower utilization of titanium metal and higher cost of titanium products. The root of this is the lack of in-depth knowledge of the ingot melting and casting process, and the failure to control the thermal conditions of the billet in the molding process within a reasonable range. In this study, based on the Lagrange Euler algorithm, combined with ProCAST finite element software to establish a numerical model, revealing the solid–liquid interface morphology, the length of the transition region, and the change rule of thermal stress under the influence of different process parameters in the solidification process of titanium slab ingot. The results show that with the increase in pulling speed, the depth of the solid–liquid phase line and the width of the mushy zone of slab ingot increase, and the length of the transition region grows. With the increase in casting temperature, the depth of the solid–liquid phase line of the slab ingot decreases, and the mushy zone gradually becomes narrower. The casting temperature and pulling speed are positively correlated with the value of the thermal stress equivalent stress in slab ingots, and the probability of cracks in the corners and ingot surface is higher. This study provides effective theoretical guidance for the realization of stable mass production of high-quality titanium slab ingot.
Effect of Cu content on the microstructure and properties of sintered Fe-0.8C-xCu antifriction materials
Authors: Li Jiaxin , Feng Han , Zhang Jianhua , Chen Pengqi , Cheng Jigui 
Published: August 2024

Abstract
Ferrous antifriction materials (FAMs) play a crucial role in powder metallurgy. Previous studies have primarily focused on exploring the antifriction properties of Fe-C-Cu materials with low copper content (0–5 wt%), while there have been fewer studies on high copper content FAMs. In this study, to investigate the effect of Cu content on the microstructure and properties of sintered FAMs, Fe-0.8C-xCu (x = 5–25 wt%) materials were prepared by powder metallurgy method. The density, microstructure, mechanical performance, friction and wear properties of the samples were analyzed. The results demonstrated a significant change in the relative density, hardness, friction and wear properties of sintered Fe-0.8C-xCu samples with increasing Cu content. Particularly, the Fe-0.8C-15Cu samples exhibited outstanding properties, with a relative density of 77.8%, a hardness of 43 HRB, crushing strength of 380 MPa, an average friction coefficient of 0.21, and a wear rate of 1.36 × 10−8 mm3 N·mm−1. The primary wear mechanisms of the Fe-0.8C-xCu specimens include abrasive wear, adhesion wear, chafing fatigue, pitting, and oxidation. This study aims to provide an experimental and theoretical basis for the development of ferrous antifriction materials suitable for heavy-load conditions.
RF coil that minimizes electronic components while enhancing performance for rodent MRI at 7 Tesla
Authors: Vazquez F , Villareal A , Lazovic J , Martin R , Solis-Najera S E , Rodriguez A O 
Published: August 2024

Abstract
This study introduces a novel volume coil design that features two slotted end-plates connected by six rungs, resembling the traditional birdcage coil. The end rings are equipped with six evenly distributed circular slots, inspired by Mansfield’s cavity resonator theory, which suggests that circular slots can generate a baseline resonant frequency. One notable advantage of this proposed coil design is its reduced reliance on electronic components compared to other volume coils, making it more efficient. Additionally, the dimensions of the coil can be theoretically computed in advance, enhancing its practicality. To evaluate the performance and safety of the coil, electromagnetic field and specific absorption rate simulations were simulated using a cylindrical saline phantom and the finite element method. Furthermore, a transceiver coil prototype optimized for 7 Tesla and driven in quadrature was constructed, enabling whole-body imaging of rats. The resonant frequency of the coil prototype obtained through experimental measurements closely matched the theoretical frequency derived from Mansfield’s theory. To validate the coil design, phantom images were acquired to demonstrate its viability and assess its performance. These images also served to validate the magnetic field simulations. The experimental results aligned well with the simulation findings, confirming the reliability of the proposed coil design. Importantly, the prototype coil showcased significant improvements over a similarly-sized birdcage coil, indicating its potential for enhanced performance. The noise figure was lower in the prototype versus the birdcage coil (NF
birdcage − NF
slotcage = 0.7). Phantom image data were also used to compute the image SNR, giving SNRslotcage/SNRbirdcage = 34.36/24.34. By proving the feasibility of the coil design through successful rat whole-body imaging, the study provides evidence supporting its potential as a viable option for high-field MRI applications on rodents.