bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymorphic protein phase transitions driven by surface anisotropy
Authors: Strofaldi Alessandro , Quinn Michelle K. , Seddon Annela M. , McManus Jennifer J.
Published: December 2022

Phase transitions of proteins are strongly influenced by surface chemical modifications or mutations. Human γD-crystallin (HGD) single-mutants have been extensively studied because they are associated with the onset of juvenile cataract. However, they have also provided a rich library of molecules to examine how specific inter-protein interactions direct protein assembly, providing new insights and valuable experimental data for coarse-grained patchy-particle models. Here, we demonstrate that the addition of new inter-protein interactions by mutagenesis is additive and increases the number and variety of condensed phases formed by proteins. When double mutations incorporating two specific single point mutations are made, the properties of both single mutations are retained in addition to the formation of a new condensed phase. We find that the HGD double-mutant P23VC110M self-assembles into spherical particles with retrograde solubility, orthorhombic crystals, and needle/plate shape crystals, while retaining the ability to undergo liquid–liquid phase separation. This rich polymorphism is only partially predicted by the experimental data on the constituent single mutants. We also report a previously un-characterized amorphous protein particle, with unique properties that differ from those of protein spherulites, protein particulates previously described. The particles we observe are amorphous, reversible with temperature, tens of microns in size, and perfectly spherical. When they are grown on pristine surfaces, they appear to form by homogeneous nucleation, making them unique, and we believe a new form of protein condensate. This work highlights the challenges in predicting protein behavior, which has frustrated rational assembly and crystallization but also provides rich data to develop new coarse-grained models to explain the observed polymorphism.
Tailoring the structural and magnetic properties of self-ordered nickel nanowires created by template-assisted electrodeposition route
Authors: Salem Mohamed Shaker , Mahdy Manal A.
Published: December 2022

Thin films of vertically oriented self-ordered nickel nanowires were fabricated using the template-assisted electrodeposition method. Magnetic measurements of as-formed nanowires revealed the presence of an axial easy magnetization direction due to the shape of the nanowires. At moderate annealing temperatures, the magnetic anisotropy changed from positive to negative. This indicated easy magnetization direction flipping from axial to radial configuration. A nickel oxide phase started to grow at higher annealing temperatures with a distinct reduction in saturation magnetization due to its antiferromagnetic character. In addition, an exchange bias was observed owing to the coexistence of ferromagnetic and antiferromagnetic phases. Single-phase nickel oxide nanowires were generated at elevated annealing temperatures and exhibited an unexpected ferromagnetic behavior attributed to the incorporation of nickel ions and oxygen vacancies as suggested by ferromagnetic resonance measurements. Diffuse reflection measurements indicated an effective energy gap of 4.2 eV for nickel oxide nanowires.
Enhanced light extraction by optimizing surface microstructure for AlGaN-based deep ultraviolet light emitting diodes with 265 and 280 nm emission
Authors: Zhu Yifan , Lu Huimin , Wang Jianping , Yu Tongjun , Li Zizheng , Tian Yucheng
Published: December 2022

In order to improve the light extraction for the deep ultraviolet light emitting diodes (DUV-LEDs), the surface microstructure based on a parabola cone array is used and optimized in work. In the optimization of the surface structure, inverse design based on a particle swarm optimization intelligent algorithm is applied to maximize the light extraction. The optimization results show that compared with the traditional planar structure, the optimized surface structure improves the light extraction efficiency by more than 200%. In addition, the influence of the designed surface microstructure on the light propagation is also explored by comparing the light field distribution and the light extraction process with the planar structure DUV-LEDs. It is revealed that the high aspect ratio of an array microstructure can change the light propagation and greatly expand the angle of a light escape cone. This effect can be maximized by the inverse design based on the intelligent algorithm, which has great potential in improving the light extraction of AlGaN-based DUV-LEDs.
A multifunctional metasurface with asymmetric transmission and high-efficiency cross-polarization converter
Authors: Fu Yang , Cheng Houyuan , Wu Jiong , Li Yujun , Dai Yilin , Wen Dinge , Yang Helin
Published: December 2022

A three-layer multifunctional metasurface structure is proposed to achieve polarization rotation, perfect polarization conversion, and asymmetric transmission. The design consists of mutually perpendicular rectangular patches, metal pillars, and open-slit metal sheets. By propagating the current through the metal pillars and changing the surface current direction, the dipole can be orthogonally steered to accomplish polarization conversion. The metal in the middle layer can be used to both improve the polarization conversion ratio and ensure high transmittance. The operating band of asymmetric transmission is 8.3–14.7 GHz, where the conversion ratio is above 90% in all of 9–14.2 GHz. In order to verify the proposed concept, the related parameters are designed and measured, the final experimental results match with the simulation results, and the design can be used in the radome, electromagnetic stealth.
Physics-informed sparse identification of bistable structures
Authors: Liu Qinghua , Zhao Zhenyang , Zhang Ying , Wang Jie , Cao Junyi
Published: December 2022

The design of bistable structures is a hot topic in the last decade due to its wide application in smart actuators, energy harvesters, flexible robotics, etc. The characterization of the nonlinear restoring force of bistable structures plays a significant role in modeling and enhancing dynamic performance. However, the traditional nonparametric identification methods may have insufficient accuracy or even be invalid because of numerical differentiation procedures and static fitting. Besides, the modern data-driven sparse regression identification methods rely highly on the assumed nonlinear basis functions and lack interpretability. In this paper, a physics-informed sparse identification method is proposed for the nonlinear restoring force identification of bistable structures. The function of the nonlinear restoring force is physically informed by the derived equation of the Hilbert transform and parameter fitting. Furthermore, sparse identification is conducted based on the free vibration responses of the bistable vibrator. The numerical studies verify the effectiveness of the proposed algorithm under the noise level of 30 dB. Experimental measurement is conducted on a magnetic coupled bistable beam to perform the model identification. It has been demonstrated that the reconstructed dynamic response and nonlinear restoring force both keep in good agreement with the measured ones.
ITER relevant multi-emissive sheaths at normal magnetic field inclination
Authors: Tolias P. , Komm M. , Ratynskaia S. , Podolnik A.
Published: December 2022

Reliable modeling of macroscopic melt motion induced by fast transients requires the accurate and computationally efficient description of the emitted current density that escapes to the pre-sheath. The ITER sheaths that surround hot tungsten surfaces during edge-localized modes are characterized by important contributions from secondary electron emission and electron backscattering as well as by the coupling between thermionic emission and field electron emission. Under the guidance of systematic particle-in-cell simulations that incorporate a comprehensive analytical electron emission model, a highly accurate semi-empirical treatment of the escaping electron current has been achieved.
Study on a Base-galloping Hybrid Excitation Piezoelectric Vibration Energy Harvester
Authors: Gao Mingyang , Liu Wenguang
Published: December 2022

Vibration response and performance of a piezoelectric energy harvester under the hybrid excitation of base vibration and galloping is studied. Based on the Euler-Bernoulli beam theory, the distributed-parameter model of a piezoelectric cantilever beam with base and galloping hybrid excitation is derived. Subsequently, the electromechanical coupled reduced order model and the decoupling model of the system is obtained. Thereafter, the analytical solution of the vibration response and the coupling relationship between the two hybrid excitations are analyzed. In the end, the impacts of the load resistance, the excitation acceleration and the wind speed on the power generation performance of the system are examined. Results indicated that the hybrid excitation can not only increase the energy harvester power of the system by 2.4W, but also effectively broaden the frequency band compared with the single foundation excitation. The research result is helpful to the dynamic design of a piezoelectric vibration energy harvesters under hybrid vibration excitation.
Structural Design and Performance Analysis of Tilting-pad Sliding Bearing for Marine gas Turbine
Authors: He Yuliang , Zhang Gang , Li Xu , Bian Shiji
Published: December 2022

With the strategic transformation of our country’s navy, the defense capability of long distance needs to be improved, which has higher requirements on the reliability and life of gas turbines. Bearing system is one of the factors that restricts the life and reliability of gas turbines. The fundamental reason is that the rolling bearings used have limited life and low reliability. Since sliding bearings have higher reliability, longer service life and lower maintenance costs, in order to improve the operation stability of a certain type of gas turbine which works under complex conditions, the former supporting elements were replaced with the more reliable tilting-pad sliding bearings. Its structure is designed according to the original structural dimensions. After finishing the structure design, we analyze the static characteristics of the designed bearing from the aspects like oil film pressure, oil film thickness, bearing capacity and so on, combining with the relevant Matlab program and provide a reference for the subsequent theoretical analysis after completing the subsequent bearing on-machine test.
Study on silencing performance of small hole injection muffler in sealed cabin
Authors: Ren Yafei , Yang Dongsheng , Zhao Jian , Xie Wen , Du Guofei , Liu Guofeng , Huang Xin
Published: December 2022

The astronauts need to re pressurize the sealed cabin after returning to the sealed cabin. The noise generated in the process of re pressurization is too large, so a silencer shall be set to reduce the noise in the cabin. Through theoretical analysis, this paper selects the small hole injection muffler, makes theoretical calculation, and determines the specific structural size of the muffler. The test shows that when the cabin pressure rises to 85kpa, the use of the small hole injection silencer can reduce the cabin noise from 85.7db to 66.3db, which meets the medical requirements of astronauts.
Optimal design of permanent magnet motor based on Taguchi algorithm
Authors: Yang Miaomiao , Xu Yufa , Cheng Sheng
Published: December 2022

Aiming at the optimization of cogging torque of 12 pole 36 slot embedded permanent magnet motor, analyzing the generation principle of cogging torque, putting forward the optimization design of auxiliary slot based on Taguchi method, using Maxwell finite element simulation tool, analyzing and selecting the optimized data, through orthogonal experiment and data processing, finding the final optimization scheme of auxiliary slot. The simulation results show that, the auxiliary slot optimization method based on Taguchi method can effectively suppress the cogging torque under reasonable slotting rules, which is also of reference significance to other types of parameter optimization.
Effects of Deflection Mode on Flared-Maneuver Performance of Unpowered Heavy Airdrop System
Authors: Wu Yutong , Yang Dongyu
Published: December 2022

For the landing process of a large-scale airdrop system, flared-maneuver is a common approach to decelerate to prevent huge impacts while touching down. A 6-DOF model of parafoil-load system is used to investigate the effects of different deflection modes on airdrop system’s landing performance. By numerical simulation, three main factors, distance of deflection, rate of deflection and the pattern of rate changing, are discussed according to the results. The conclusion derived is of some significance in assisting control and design of landing procedure of such unpowered heavy airdrop systems.
Analysis of internal flow field performance of hydrocyclone based on CFD
Authors: Rao Gang , Zhao Hu
Published: December 2022

This paper uses CFD software ANSYS Fluent, based on RSM Reynolds stress model and VOF two-phase flow model, to calculate the turbulent flow field inside the ∅75mm heavy dispersed phase particle separation cyclone. Combined with the experimental working parameters under different inlet pressures, the experimental results were compared. Check the accuracy of the formula calculation results and the numerical simulation results. The results show that the air column inside the cyclone is stable and the internal pressure gradient is continuous Well, the numerical simulation results of the axial and tangential velocity fields are consistent with the reality. Compared with the empirical formula, fluent numerical simulation software can more accurately predict the processing capacity of hydrocyclone, and the classification efficiency obtained is close to the experimental value.
Blades layout and optimization of medium specific speed centrifugal pump
Authors: Wang Jinlong , Zhang Xiaqi , Chen Hui
Published: December 2022

In this paper, a centrifugal pump of medium specific speed is taken as the research object, and the performance changes of the centrifugal pump are studied by setting five different ratio degrees of blades. The results show that due to the shortening of the blade length, the pump head and efficiency both decrease with the decrease of the ratio degree. In terms of static pressure distribution, the high pressure area in the volute expands from the outlet to the upstream with the decrease of the ratio degree, and forms an obvious boundary layer with the pressure in the impeller. Under the rated flow, the model pump with ratio degree R=2/3 has the best cavitation performance. When the number of impeller blades with a ratio of 2/3 was optimized, the flow field performance of the model pump with 8 blades was the best, and the head increased by 7.33% compared with the prototype pump at rated flow.
Thermal load analysis and structure optimization of neutral beam injector cryosorption pump
Authors: Liu Xiaoxue , Tang Ning , Cui Zhiwei , Xie Yuanlai
Published: December 2022

In order to meet the high vacuum requirement of neutral beam source, cryosorption pump is used as the main pump, and the pumping performance of cryosorption pump depends on its cryogenic performance. To test and verify the feasibility of cryosorption pump steady running, modular design based on cryosorption pump, composed of 16 extraction unit in series, in a single suction unit as the research object, respectively for radiation and cryosorption pump baffle panel of the theory of heat load, and will result in finite element analysis software, the analysis of the temperature field of two structures, respectively and extraction unit structure optimization direction is put forward. The simulation results show that the normal operating temperature of the cryosorption pump can be reached under steady-state operating conditions, and the cryogenic performance of the extraction unit can be improved after the optimization of the structure, thus providing reference for the optimization of the cryogenic pump group.
An Experimental Study on the Effect of Liquid Concentration on the Atomization Performance of Low-pressure Atomizing Nozzles
Authors: Lei Han , Li Ge , Wang Fei , Chen Tiejun , Ten Li , Ding Yong
Published: December 2022

in order to study the phenomenon and mechanism of paint low-pressure atomization spraying and improve the spraying technology, the effect of liquid concentration on the atomization performance of low-pressure atomizer was studied. In this paper, an experimental platform for measuring the spraying of low-pressure atomizing nozzle was built. Mixing the same paint with clean water to obtain liquids of three different concentrations and using them as the mediums respectively, the flow, the atomization angle and the atomization characteristics of low-pressure fine atomizing nozzle with aperture of 0.33mm under the pressure of 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa and 0.8MPa were studied. The measured experimental data show that there is a positive correlation between the flow of atomizer and atomization pressure, and the larger the liquid concentration is, the smaller the flow is; The variation trend of atomization angle with the increase of pressure is related to the liquid concentration and is stable between 45 ° and 60 °; The average droplet size of atomized droplets has a negative correlation with atomization pressure, and the higher the liquid concentration, the larger the average droplet size. The experimental results show that the liquid concentration has a significant impact on the atomization performance of low-pressure atomizer, and the measured data are helpful for the application of paint spraying under low-pressure conditions.
Production of Solar-powered Quad-copter for Agricultural Field Spraying
Authors: Xu Ying , Dan Yanghui , Raymond Mwanza Taipa
Published: December 2022

To meet the requirements of ultra-low space flight in pesticide spraying applications, a quadcopter with independent attitude control was proposed. It is a new product of a miniature quadcopter aircraft powered by solar cells. The innovation of this study was the adoption of circular frame structure, which increases the laying area of solar panels. The solar energy is used to convert lithium battery power supply to increase the altitude during navigation. Describes in detail the selection of components and the assembly process of this quadcopter, and conducts a test flight of the quadcopter. on this basis, the flight test was carried out. From the fight results the performance indicators of the quadcopter meet the design requirements. This research has a positive effect on the development of farm operation devices
Dynamic properties analysis of ball screw feed system based on improved hybrid model
Authors: Sun Xuan , Liu Xijun , Liu Minghao
Published: December 2022

Ball screws are widely used as feed systems for machine tools due to their high transmission efficiency and long service life. However, the large inertia force generated by the ball screw in high-speed motion will excite its flexible mode and cause system vibration. In the actual working condition, the dynamics of the system will also change with the nut position and workpiece mass. In order to further study the modeling method and dynamic properties of the ball screw feed system, this paper firstly improves the traditional hybrid model by introducing an energy loss factor to modify the hysteresis damping of the model. Further, the rationality of the improved model is verified by hammer test. Finally, the model was used to analyze the dynamic properties of the system and to obtain the influence law of workpiece mass and nut position on the system natural frequency.
High clearance four-wheel independent electric drive sprayer path tracking control based on self-correction controller
Authors: Liu Guohai , Zhang He , Zhang Duo , Shen Yue , Wang Zijie , Xu Yandong
Published: December 2022

Most traditional agricultural machines use traditional mechanical transmission with fuel drive and front wheel steering, and most of them are manned, with low transmission efficiency, poor flexibility and low level of intelligence. This paper proposes a new high ground clearance sprayer with four-wheel independent drive (4WID) with dual front and rear steering axles. This sprayer is an oil-electric hybrid that not only saves energy, but also reduces the pollution to crops. In this study, a path tracking controller and a self-correcting controller are constructed based on the kinematic model of the sprayer, respectively. The model prediction controller is used as the main controller, and it outputs the desired steering angle and speed of the sprayer based on the current state of the sprayer and the desired path to achieve path tracking control. The self-correcting controller, as an auxiliary controller, adopts fuzzy control method and designs fuzzy control rules based on the driver’s experience to correct the wheel turning angle at the current moment, which not only retains the advantages of model prediction control in linear path tracking, but also improves the control effect in curved path tracking and enhances the path tracking accuracy in large curvature roads. The simulation shows that the maximum lateral deviation of 0.03 m can be achieved by the model predictive control alone, and the maximum lateral deviation is reduced to 0.0141 m after adding the self-correcting controller.
Research on Time Synchronization between Shore and Ship based on Two-way Time-frequeny Transmission
Authors: Jun Xue , Qian Fang , Nanping Mao
Published: December 2022

The purpose is to study the application of two-way time comparison method for time synchronization on motion platforms such as ships. Firstly, the one-way time comparison method and the two-way time comparison method are analyzed, and the characteristics of the two methods are compared. Combined with the influence of the motion platform on the time synchronization during movement, an improved two-way comparison time synchronization method suitable for the motion platform is proposed. The time synchronization technique of bidirectional comparison based on carrier ranging principle is discussed, and the conclusion of two-station time synchronization based on carrier bidirectional time comparison under weak relative motion is obtained.
Fault Diagnosis of Jointless Track Circuit Based on ReliefF-C4.5 Decision Tree
Authors: Liu Ruidan , Dong Yu
Published: December 2022

At this stage, when judging the fault type of jointless track circuit, it mainly relies on the staff to analyze the computer monitoring data. This fault identification method has problems such as high dependence on staff and long fault identification cycle. In order to solve the above problems, the combination of the reliefF algorithm and the C4.5 decision tree is introduced into the fault diagnosis of the jointless track circuit. First, the reliefF algorithm is used to give weights to the selected 9 feature parameters according to the fault classification ability of the features. Second, sort the feature parameters according to the weight, and select the first seven feature parameters as the optimal feature subset. Finally, complete the training and testing of the classifier with the optimal feature subset. The experimental results show that the fault diagnosis accuracy of ReliefF-C4.5 Decision Tree is 93.33%, So the fault diagnosis model proposed in this paper is suitable for fault diagnosis of track circuit.
Research and experiment on control loop system of Source Measure Unit
Authors: Han Haitao , Mou Bingrui , Song Jie , Wang Zixin
Published: December 2022

Aiming at the problem that the capacitive load of the source measure unit (SMU) system affects the stability of the loop control, this paper makes an in-depth theoretical analysis of the loop control system based on the SMU. A theoretical and circuit model is established after the analysis. In the control loop structure, an integrator with proportional amplification serves as an error amplifier for the control loop system to obtain sufficient phase margin at the optimal bandwidth. A phase-lead compensation capacitor scheme is studied and proposed to achieve the maximum tolerance range to achieve the loop stability. The results show that the simulation and experimental results are basically consistent. The results verify the theoretical correctness and practical value of this SMU control loop system, and provide a theoretical basis for the research of the SMU control loop structure of the subsequent SIP process.
Research on fault diagnosis of hot die forging multi-station feeding manipulator
Authors: Yang Dong
Published: December 2022

In order to improve the efficiency of fault diagnosis of hot die forging multi-station feeding manipulator, according to the fault characteristics of the feeding manipulator, an expert system structure based on fault tree analysis and binary decision graph was designed, and a diagnosis method based on expert system was proposed. Firstly, according to the fault causes of multi-station feeding manipulator, the fault tree is established. Secondly, the binary decision graph is used to analyse the fault tree, acquire the diagnosis expert knowledge, and establish the knowledge base of fault diagnosis. Then, the binary decision graph is used to quantitatively analyse the fault tree, the importance of the minimum cut set is solved, and the rule priority is determined, so as to solve the rule conflict problem and improve the efficiency of fault diagnosis. Finally, a case study is conducted. The results prove the validity and feasibility of the fault diagnosis method proposed in this paper.
PCB defect detection system based on image processing
Authors: Cai Li , Li Jingchuan
Published: December 2022

Under the background of intelligent manufacturing, the quality inspection of printed circuit board (PCB), as the carrier of electronic products, plays an important role. In view of the shortcomings of existing traditional detections, this paper has put forward a PCB detection method based on machine vision, focusing on image preprocessing algorithm and detection analysis. The median filter algorithm was used to remove the noise in the image. Logarithmic transformation was used to enhance image contrast. Sobel operator was used for edge detection to obtain the geometric center of the defect area. On this basis, the PCB image was registered by template matching method, and the difference between the preprocessed PCB image to be tested and the standard PCB image was calculated to get the difference map. Subsequently, morphological algorithm was used to remove the slight differences and obtain the defect map. In the end, the simulation results have shown that the proposed algorithm has good detection effect and high precision in PCB defect detection.
Simulation study of an improved firefly algorithm for solving multi-dimensional complex function optimization
Authors: Wang Liping
Published: December 2022

To address the shortcomings of the traditional firefly algorithm in global optimization seeking, such as low solution accuracy, unstable convergence and slow optimization speed, a new evolutionary model of firefly algorithm based on the improved Chebyshev chaos mapping is proposed. Firstly, the population distribution is initialised with the improved Chebyshev chaos mapping to improve the population diversity. Secondly, the non-linear dynamic adaptive inertia weights are introduced to regulate the balance between convergence speed and local optimality seeking ability. Then, the boundary variation strategy is introduced to solve the boundary crossing problem to avoid falling into local optimum and continue to improve the population diversity. Finally, simulation experiments are conducted under six benchmark test functions to compare with the traditional firefly algorithm. The experimental results show that the improved algorithm has higher solution accuracy and faster convergence speed.
Simulation of energy recovery system of high speed transmission shaft dynamic torque test bench
Authors: Chen Xinyuan , Zhang Zhenjun
Published: December 2022

A hydraulic energy recovery and control system is proposed to solve the energy loss problem of the current vehicle transmission shaft torque test bench. On the basis of the original system, power recovery is realized by parallel hydraulic compensation. PID module is used to control the displacement of piston variable pump and motor respectively to adjust the speed and torque to achieve the established working conditions. The feasibility of the hydraulic system and control scheme is verified by AMEsim-MATLAB software and experiments. The results show that the proposed system can not only adjust the set speed and torque dynamically, but also achieve high power recovery.
Research on iterative learning control of lower limb exoskeleton of rehabilitation robot
Authors: Zhang Min , He Min
Published: December 2022

It is difficult to establish an accurate mathematical model for the lower limb exoskeleton system of a rehabilitation robot, and there are unknown external disturbances. In this paper, an accurate model-independent closed-loop PD-type iterative learning control algorithm is adopted, which enables the system to track a given desired trajectory with uncertain dynamic models and parameters. The simulation results show that the algorithm can effectively improve the control accuracy of the trajectory tracking of the lower limb exoskeleton.
Effects of Particle Size and Content of Aluminium on Mechanical Properties and Reaction characteristics of Al/THV Reactive Materials
Authors: Xu Shupeng , Wang Yinjie , Yang Zenglin , Zhao Xiuchen , Tan Chengwen
Published: December 2022

The metal/fluoropolymer reactive materials (RMs) have been widely studied in the past years. Almost no reported Al/THV RMs, which was prepared in this work, shows better mechanical properties than well researched Al/PTFE. In addition, the mechanical properties and reaction characteristics of Al/THV composites with two particle sizes and different contents of aluminium particles were tested. The effects of particle size and content of aluminium on Al/THV RMs were analysed. The result shows that Al/THV composite with high contents of 4 μm Al particles shows better mechanical properties and reaction characteristics than the other Al/THV composites. Besides, the low impact-induced reaction percentage of Al/THV (35/65) composite under ~7000 s-1 compression was explained by the low combustion velocity and plasticity.
Manganese residue modified steel slag to improve low-temperature SCR of NOx
Authors: Li Hongzhe , Mao Xinyi , Zhang Mingjie , Chen Yipei , Yang Gang
Published: December 2022

In this study, the denitrification performance of steel slag modified by manganese slag was studied. Different proportions of steel slag and electrolytic manganese anode mud mixtures were configured. The different proportions of the mixture would have varied physical and chemical properties. SS1+EMAM2 catalyst showed the nearly 100% NOx removal efficiency at 175°C. The specific surface area of steel slag is enhanced dramatically after modification by EMAM. Adding EMAM enhanced the weak acid sites and Brønsted-acid sites on the catalyst surface, resulting in a higher low-temperature SCR activity.
Research on Heat Dissipation Scheme of Active Magnetic Bearing Based on ANSYS
Authors: Li Dongjie , Zhang Gang , Li Zhuoyuan , Sun Jinhua
Published: December 2022

Compared to mechanical bearings, active magnetic bearings eliminate mechanical friction, resulting in lower energy losses. However, due to the magnetization characteristics and high-frequency working characteristics of the core material of the active magnetic bearing, there will be high wind friction loss, eddy current loss, hysteresis loss and copper loss in the active magnetic bearing. These losses will generate heat and increase the internal temperature of the bearing, which will not only affect the control accuracy of the active magnetic bearing and the stability of the rotor suspension, but may also cause irreversible damage to the components inside the active magnetic bearing. In this paper, different heat dissipation schemes are established to discuss the influence of the active magnetic suspension bearing on the loss and heat generation of the active magnetic bearing.
Surface Modification of Carbon Nanotubes by Ar Plasma Jet
Authors: Liu Jingjing , Mu Jinjun , Tan Wenchao , Zhong Yingying
Published: December 2022

Atmospheric pressure low temperature plasma jet (APPJ) is a technical direction that has attracted much attention in recent years. In this paper, argon is used as the working gas to produce highly active ions through funnel shaped glass tubes to modify the surface of carbon nanotubes. After the carbon nanotubes treated for 4 mins, SEM, water contact angle and FTIR detection results were compared before and after the experiment. The results showed that the hydrophobicity of carbon nanotubes was enhanced and the surface dispersion was improved after DBD plasma jet treatment.
Effect of welding parameters and post-welding heat treatment on the microstructure and properties of weld seam of 20# steel and 304 stainless steel
Authors: Li Lian-jie , Hu Wan-qing
Published: December 2022

According to the influence of welding process between 304 austenitic stainless steel and 20 steel dissimilar steel on the weld seam, the effects of welding current of 150A, 180A and 200A, normalizing and solution treatment on the microstructure and properties of the weld seam were studied by using MAG. The results show that the 150A current welding seam has incomplete fusion, which leads to its low strength and fracture toughness. With the increase of current, the necking fracture occurred on one side of 20 steel, and the brittleness and hardness of weld increased, all of which indicated that carbon element diffused from 20 steel to weld and 304 stainless steel. Although the corresponding post-welding heat treatment can reduce the hardness to a certain extent, improve the machining performance of welded joints and homogenize the microstructure of welded joints, it can’t significantly improve the performance of welded joints of dissimilar steels.
Removal of non-magnetic impurities on the surface of NdFeB magnets
Authors: Ren Meng , Li Jun , Li Jian , Yang Song , Zhang Shouhua , Li Bo
Published: December 2022

NdFeB rare earth permanent magnets are widely applied in numerous fields including consumer electronics, industrial motors and new energy vehicles. Sintered NdFeB magnets are prepared by pressing and high-temperature sintering, followed by machining into desired shapes with anisotropism and high magnetic properties. During industrial production process, the appearance of non-magnetic impurities adhering on NdFeB magnet surface is a critical problem, which takes bad influences to not only magnetic properties of NdFeB, but also the qualification rate of subsequent assembled parts. There are two forms of impurities, one is gelatinous and the other is filamentary. In this paper, non-magnetic impurities on the surface of NdFeB magnets were characterized and analyzed by FTIR, EDS and SEM, and the methods to remove impurities were studied. The results showed that gelatinous impurities are stearamide derivative, which can be dissolved by xylenes under heating conditions. Filamentous impurities are cellulose derivative that can be removed by economical sodium hydroxide-urea system instead of expensive AmimCl, without damaging magnet plating and magnetic properties.
Development and Experimental Analysis of Friction Torque Testing Machine for Planetary Thread Roller Bearing
Authors: Liu Ziyu , Fu Yongling , Zheng Shicheng
Published: December 2022

In order to measure the friction torque of planetary thread roller bearings, a friction torque testing machine was developed based on the principle of transfer method. The test of dynamic friction torque and starting friction torque under axial and radial continuously adjustable large load conditions is realized. The test machine has good stability, and the test data are accurate and reliable, providing data support for in-depth understanding of the friction performance of planetary thread roller bearings.
Study on Rolling Bearing Life Based on Weibull Distribution and Correlation Coefficient Optimization and Maximum Likelihood Estimation
Authors: Liu Ziyu , Fu Yongling , Zheng Shicheng , Wei Jinkun
Published: December 2022

For the reliability evaluation of rolling bearing life, this paper proposes a parameter estimation method based on the correlation coefficient optimization method and the maximum likelihood estimation method (Cor-MLE), which can obtain more accurate Weibull distribution parameter estimation. Subsequently, the feasibility of Cor-MLE method for Weibull parameter estimation was verified by Monte Carlo simulation data and rolling bearing life test data. Compared with the parameter estimation results of least square method, grey model method and correlation coefficient optimization method, it is proved that the estimation results of this method have high accuracy and can meet the life analysis of rolling bearings.
Homogenization of TiVTaNb refractory high-entropy alloy
Authors: Chen Jingwen , Dong Yaguang , Jin Ke , Wang Benpeng , Xue Yunfei
Published: December 2022

Homogenization of refractory high entropy alloys (RHEAs) usually requires very high annealing temperatures and long periods due to the high melting temperature of alloying elements and the sluggish diffusion effects. TiVTaNb is a typical RHEA with excellent mechanical properties. The present work takes TiVTaNb as a model alloy and shows the influence of cold-deformation, annealing temperature, and annealing time on its homogenization microstructure. The optimal process parameters are determined as cold deformation of 80% thickness reduction, followed by annealing at 1250 °C for 48 h. The tensile deformation behavior of the homogenized alloy is then studied based on quasi-in situ tensile testing, showing a tensile strength of 766 MPa. The tensile deformation is accompanied by grain rotation, meanwhile, a large number of geometrically necessary dislocations piles-up at the grain boundaries.
Research on hydrogen permeation in the X80 steel heat-affected zone with different heat inputs
Authors: Gou Jinxin , Deng Xiangyuan , Cui Gan , Xing Xiao , Li Zili
Published: December 2022

Through electrochemical hydrogen permeation experiment at different hydrogen charging current densities, the hydrogen diffusion kinetic parameters such as penetration time tB
, steady-state hydrogen permeation current density I
∞, hydrogen diffusion coefficient D, adsorbed hydrogen concentration C
0, hydrogen flux J, and hydrogen trap density NT
in the heat-affected zone of X80 steel welding with different heat input were analyzed. The results show that the penetration time gradually decreases, and the I
∞ gradually increases with the increase of hydrogen charging current density. The penetration time of BM at the same hydrogen charging current density is the smallest, and the penetration times of CGHAZ specimens with different heat input conditions are relatively close. BM has the most significant hydrogen diffusion coefficient and negligible hydrogen trap density at the same hydrogen charging current densities. For CGHAZ, D significantly decreases and NT
substantially increases, and there exists a threshold value that makes the lowest D in the CGHAZ with different heat inputs.
Fatigue test fracture analysis of aircraft blade connecting pin
Authors: Wang Zhanbin , Chen Guoquan , Jiang Tao
Published: December 2022

During the fatigue performance verification test of the blade simulator, a fixed connecting pin on which the splint was installed broke. In this paper, the fracture properties of the connecting pin were determined by observing the macro/micro morphology of the connecting pin and the fracture surface of the coating. By analyzing the elements, structure, hardness and relative ratio of the body and coating, the differences between the connecting pins of different blades were studied, and the fracture causes of the connecting pins were comprehensively analyzed. Based on the above experiments, the influence of coating quality on fatigue cracking is analyzed, and the improvement scheme of connecting pin is put forward.
Microstructure and dielectric properties of CaCu3Ti4O12-xCeO2 ceramics
Authors: Yu Yunfei , Wang Qun
Published: December 2022

(1-x)CaCu3Ti4O12-xCeO2 (x=0.1, 0.2, 0.3, 0.4) and CaCu3Ti4O12 ceramics were synthesized through a solid-state reaction technique. X-ray diffraction indicates that the CaCu3Ti4O12 phase is formed in all ceramics. SEM micrographs show that the grain size of ceramics declines with the addition of CeO2, which is attributed to the solute drag effect. When the addition amount of CeO2 is 0.4, the ceramic obtains the maximum dielectric constant at low frequency. Increasing the composite content of CeO2 can effectively reduce the dielectric loss of CCTO ceramics at high frequency. And the lowest value is 0.1 when the addition amount of CeO2 is 0.3. Impedance analysis shows that the lowest dielectric loss obtained for the ceramic is due to the lowest grain resistance.
Study on the priori method of vibration anomalies in the pipeline of a Synchronous condenser
Authors: Wan Yu , Lin Shaochen , Gao Yan
Published: December 2022

Abnormal vibration may occur in the pipeline of cooling and lubrication system of synchronous condenser during operation. In order to solve this problem, a priori analysis method for abnormal vibration of synchronous condenser piping system is proposed in this paper. This method mainly includes three parts :(1) the modal analysis of the whole pipeline system is carried out to find the pipeline with the most dangerous abnormal vibration; (2) Analyze the cause of abnormal vibration of the hazardous pipeline; (3) According to the analysis results of vibration causes, the field measurement is carried out, the modal analysis is verified, and then the cause and location of abnormal vibration of the whole pipeline system are determined. The results of case analysis show that this scheme can quickly and accurately find out the cause and location of abnormal vibration of the synchronous condenser pipeline system, improve detection efficiency and save cost. At the same time, the natural frequency of vibration obtained by modal analysis can provide a theoretical basis for the design and transformation of the synchronous condenser pipe system.
Research on vibration behavior and chatter stability of big-sized gear hobbing machine
Authors: Zhao Jiangkun
Published: December 2022

Self-excited chatter vibrations are the most detrimental for the quality and safety of the machining operations. To reduce the undesired vibrations, the dynamic behaviors of the machine tool-workpiece system and the chatter stability models need to be studied. In this paper, gear hobbing is studied using analytical and experimental approaches. Firstly, based on the chatter stability theory in relation to milling, analytical model of chatter stability in gear hobbing process is derived. Secondly, a new approach is presented to identify dynamic modal parameters using operational modal analysis (OMA). Using natural excitation technique (NExT) and auto regressive moving average (ARMA) model time series analysis method. At last, the prediction capability is verified using machining experiments, and the results show that the stability diagrams is of great potential to supply guidance for the processing parameters development.
Prediction of Future NBA Games’ Point Difference: A Statistical Modeling Approach
Authors: Han Ruize , Shi Shunying , Hu Tianrui , Tao Sijian
Published: December 2022

Nowadays, the popularity of the NBA along with the penetration of gambling ideas is rising all around the world. More and more fans prefer to bet on sports gambling. People want to predict the final score difference for each individual game. In addition, there are many either superficial or underlying factors that will affect the game’s result. The central claim of this article is to establish a reliable model that could predict each game’s result by extracting and analyzing previous games’ outcomes. The major analysis is done by modeling and exploratory data analysis, and is composed of several graphical methods. For the modeling part, ideally the model could predict the games’ score differences by analyzing previous dozens of games’ data sets. The database consists of four seasons 2013-2017 on Goldsheet website to explore more analysis. Then step by step checking and demonstrating to prove the feasibility and precision of the model. The model will collect and analyze the data information, like teams, rebounds, assists, turnovers, three points, free throws, blocks, and injury data. Considering the transfer between teams and other changes, the model will predict the future game result in each season independently by using each team’s previous game result in that season. This article indicates the idea of linear regression model to find the best fit by comparing the correlation strength of each variable, which include the home-field advantage, teams’ technical statistics, and injury data, to the result of a game. The model final outcomes implies that the game’s result has the most correlation with the home-field advantage and player injury; however, team’s basic technical statistics, included the rebounds, blocks, turnovers, free throws, three points, and assists, have low correlation coefficient with the result to demonstrate that they are not significant to a game’s result.
Fluxion Form Comparison between Newton Fluid and Bingham Fluid based on Three-Dimensional Numerical Simulation With Examples of Blood in Aorta and Water
Authors: Hu Tianmu
Published: December 2022

The rheological properties of blood is one of the most important parameter to make an influence on human health. And the numerical simulation is a popular methodology to conduct research towards the fluxion form of blood. In this dissertation, this paper uses Ansys Aim to computationally analyze the vessels based on the theory of Computational Fluid Dynamics (CFD for short). Two kinds of fluid, namely the Newton fluid, water, and the non-Newton fluid, blood, are taken into consideration. And the model of the blood’s non-Newton fluid is set as the Bingham model. Two fluids’ distributions of velocity and absolute stress are given, and the comparison of their fluxion form is done. The simulated results reveal that the biggest velocity in Bingham model is 18.07% bigger than that in Newton model, and the max difference of stress in Bingham model is 139% bigger than that in the water model. The results stated above pave the way for the subsequent research.
Finding Minimum Production Time and Optimal Procedure for a Project When Step Times are Given by Constructive Real Numbers
Authors: Li Yijia , Shan Peiyuan , Xu Tiancheng , Zhang Shenyao , Zou Tiancheng
Published: December 2022

In the production process, some jobs can only be done sequentially, while others can be done synchronously. Given the time needed to complete each job, an oriented graph with a source vertex and a sink vertex can be generated. Each route starting from the source vertex and ending at the sink vertex represents a way of completing the project. It is possible to find the minimum production time and the optimal production path when time for each job is given by a rational number. However, this paper proves that there does not exist a computer program that can always generate the minimum time and optimal path when the time needed for each job is a constructive real number.