bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low frequency electromagnetic casting of large size ZA21 magnesium alloy slab ingot
Authors: Niu Yanxia , Shi Yan , Le Qichi , Wang Yixuan , Ren Shuai , Wang Na 
Published: September 2021

Abstract
Surface quality and microstructure of ZA21 magnesium slab ingots by the direct-chill (DC) casting and low frequency electromagnetic direct chill casting (LFEC)were Deeply and systematically investigated. The surface quality of alloy ingot by LFEC casting is better than that without electromagnetic casting. The crack of ingot was avoided by applying electromagnetic field. The microstructure of ingot without electromagnetic field is coarse columnar grains, on the contrary, the microstructure of ingot by applying electromagnetic field is uniform equiaxed grains. The electromagnetic field can accelerate the flow of the melt and make the dendrite arm break to form equiaxed grains. In addition, the flow of the melt reduces the stress concentration in the solidification process, so that the crack can be avoided.
Preparation of a Novel UHMWPE Lithium Battery Separator by Electrospraying Method
Authors: Liu Taiqi , Zhao Yunteng , Han Ziye , Wu Jincheng , Zhao Rong , An Xue , Zhao Xiaomin , Li Yan , Zhang Lei 
Published: September 2021

Abstract
In this paper, an ultra high molecular weight polyethylene (UHMWPE) lithium ion battery composite separator was successfully prepared via the electrospraying technique. First, the optimal electrospraying parameters of Polyvinylidene fluoride (PVDF), mass fraction of PVDF 3wt% and electrospraying voltage 21kV, were successfully determined by adjusting the effect of voltage and concentration of PVDF solution. Then the composite separator was prepared by electrospraying PVDF particles on the UHMWPE film. Finally the porosity rate, thermal stability and charge and discharge properties of the separator were analyzed. The analytical results show that the porosity rate of the composite separator is increased from 46.5% to 73.1%, and the heat shrinkage of the separator in the longitudinal is reduced from 2.6% to 1.3%. The first specific discharge capacity of the composite separator increases by 5.8%, and the separator has a good cycle stability after 50 cycles.
Preparation of A2B7-type La-Mg-Ni Hydrogen Storage Alloy and Its Catalytic Oxidation Performance for BH4
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Authors: Xinyu Liu , Xiao Tian , Mingyue Ji , Lu Tian 
Published: September 2021

Abstract
The La-Mg-Ni hydrogen storage alloys with A2B7/AB5 double phase were successfully prepared by vacuum melting combined with ball milling. The phase structure, electrochemical properties and the catalytic oxidation properties for BH4- of the (Mm1-xMgx)Ni2.485Co0.525Mn0.28Al0.21 (x=0.1-0.5 )alloys were investigated by XRD and electrochemical measurements. The results showed that (Mm1-xMgx)Ni2.485Co0.525Mn0.28Al0.21 alloys are composed of LaNi5 phase and (La, Mg)2Ni7 phase. Among the studied alloys, the electrochemical properties of the alloy with x=0.3 is the best, and the electrochemical properties of the alloy with x=0.3 is significantly better than that of the AB5-type hydrogen storage alloy, which is mainly due to the formation of (La, Mg)2Ni7 phase in the alloy. At the same time, the alloy with x=0.3 also shows a better catalytic oxidation effect on BH4-, which is also better than that of the AB5- type hydrogen storage alloy. The catalysis of (Mm1-xMgx)Ni2.485Co0.525Mn0.28Al0.21 alloy catalyst is related to its electrochemical performance. The catalysis of hydrogen storage alloys may have a positive correlation with its own electrochemical performance.
Sample trapped charge induced signals in tapping-mode atom ic force microscopy
Authors: Wang Yu , Zhou Chuxiang , Xu Jie 
Published: September 2021

Abstract
AFM (Atomic force microscope) has been used to measure the surface topography and electrochemical properties of the sample by the interaction between the tip on the cantilever and the sample. However, when there is a charge in the sample, an induced charge will be generated inside the tip, which will generate a new attractive force between the tip and the sample and reduce the amplitude of the tip. We found that the average amplitude of the tip decreased by about 1 nm in tapping mode AFM. As the amplitude decreasing, AFM keeps the amplitude constant by adjusting z0 with negative feedback in tapping mode. So, the average charge density will affect the measurement of surface topography.
One-step hydrothermal method for preparing carbon dots and its determination of lead (II)
Authors: Shen Yongling , Wu Hongyi , Li Jian , Liu Guohong , Xiao Yanhua , Dai Zhifei , Zhen Hongling 
Published: September 2021

AbstractAs a new type of carbon nanomaterials, carbon dots have attracted great interest due to their non-toxic, low preparation cost and unique photoluminescence properties. They have been widely studied and shown great potential in many fields. Here, nitrogen doped fluorescent carbon dots were prepared by one-step hydrothermal method using Epiphyllum leaves as raw materials. Ultraviolet-visible absorption spectrometer and fluorescence spectrometer were used to study the optical properties of carbon dots. The elemental composition and morphology of the surface of carbon dots were analyzed by transmission electron microscope, Fourier transform infrared spectroscopy and X-ray photoelectron spectrometer. The results show that the prepared carbon dots are uniformly dispersed in the aqueous solution, emit blue fluorescence, and the average particle size is 4.2 nm. The carbon dots have good light stability and strong anti-photobleaching ability. Continuous spectral scanning of the carbon dots can keep the fluorescence intensity basically unchanged within 30 minutes. In the concentration of 0∼f molL-1NaCl solution, the strength is not affected by the ionic strength. In the pH range of 4∼ 8, the fluorescence intensity of carbon dots is basically stable. The heavy metal ion pb2+ has a quenching effect on the fluorescence of carbon dots, and has a good linear relationship in the range of 0.5*200 μm. Therefore, a simple and green method for pb2+ has been developed.
The development of fluid dynamics and its future application
Authors: Ni Heyang , Yao Shengtao , Zhou Zhaoliang 
Published: September 2021

Abstract
The development of fluid dynamics is essential to many related topics in mechanics. With the emerging high technology, people have begun to discover more functions suitable for fluid mechanics. This article mainly summarizes the following two aspects. One is to review the historical development of fluid mechanics on the time axis, and to summarize the important achievements of fluid mechanics in recent years. The second is to summarize the practical applications of fluid mechanics in aviation, engineering application, shipbuilding and daily life. It points out in detail the shortcomings and deficiencies in the development of computational fluid mechanics so far, and points out the direction for the future development of computational fluid mechanics.
The influence of aerodynamic on stability performance of amphibian on rough water
Authors: Huang Miao , Wu Bin , Li Chenghua , Tang BinBin 
Published: September 2021

Abstract
In allusion to the aerodynamic lift difference between tank test model and full scale plane, a simulation method of lift to tank test model is put forward, and conduct model test on rough water at the model status with boundary layer control technology (BLC) and without BLC, and then we study the influence of aerodynamic lift on trim and heaving characteristic of the test model systematically, the results turn out to be that: the influence of aerodynamic on trim is affected by test velocity, at relatively low speed, this difference can be ignored, but at higher speed, the maximum trim value difference lies the range of 2%∼7%, and the wave length corresponding to the maximum value decreases. The influence of aerodynamic on heaving is affected by wave length, at relative shorter wave length, the heaving value decreases a little between the model with BLC and without BLC, this difference lies about 10%, but this difference increases to 15%∼40% at higher wave length.
Two Simulation Methods of Brownian Motion
Authors: Liu Zhisong , Jia Yueke 
Published: September 2021

Abstract
Einstein-Smoluchowski’s theory and Langevin’s theory are two main theories to describe Brownian motion. The Einstein-Smoluchowski theory regards Brownian motion as random walking of Brownian particles, while the Langevin theory establishes a random differential equation describing the motion of Brownian particles. Both theories involve random numbers, i.e., only the statistical results can be discussed. Based on the above theories, this paper presents the corresponding simulations, which verifies the statistical conclusions as well as compares their similarities, differences, and applicable conditions. These results offer a guideline for further studies on Brownian motion.
Study on optimal design of a new type of beam-column assembled rigid joint
Authors: Chen Hong , Luo Wei , Zhao Fengbing , Tang Jiao , Geng Limei 
Published: September 2021

Abstract
With the progress of engineering technology, steel structure has become the mainstream structural form of construction engineering, and beam column composite structure is the most commonly used connection form in steel structure buildings. In order to improve the design and construction performance of beam-column joint, a new type of beam-column assembled rigid joint is proposed and its parameter optimization is analysed based on equal strength design method and finite element software. The results show that the new beam-column assembled rigid joint has excellent performance for ductility and energy-dissipating capacity and the joints and splice plates can both meet strength requirements. The number of bolts and the length of cantilever beam have great influence on the ultimate bearing capacity and ductility of the joint. The new type of beam-column assembled joint is easy to construct and has good mechanical properties, and its ductility and elastoplasticity are better than those of ordinary joints without splicing.
Contact Problem with Friction of Rolls
Authors: Zhang Ping , Lu Xiao-jun 
Published: September 2021

Abstract
Based on the engineering background of the roller of steel rolling, researching the contact problem of two long parallel cylinders and considering the infection of friction. Gained the stress expressions when the vertical load and the friction act on the rolls separately, then according with superposition theorem of elastic mechanics, gained the stress expressions with the contact pressure and the friction force combined action.
Study on interfacial connecting properties of small molecule intervention repairable epoxy composites
Authors: Zhao Tianyu , Bai Heshan , Lei Zhenkun , Bai Ruixiang 
Published: September 2021

Abstract
The interfacial bonding method and mechanical properties of new repairable epoxy and its composites were studied. Ethylene glycol was used to connect the resin interface. The effects of temperature, time and resin content on the strength of interface bonding were systematically studied, and the optimal bonding scheme was determined. The results show that this connection method has significant advantages, and the tensile strength reaches 73% of the intact resin. Furthermore, the reparable resin matrix fiber-reinforced composite was prepared, and this method was successfully extended to the composite connecting. The interfacial shear strength of the fiber composites reached 21.88 MPa by single lap test, which has a good application prospect.
A study on the mechanism of morphing features of tuna median fins during C-turns
Authors: Xiaohu Li , Zhen Su 
Published: September 2021

Abstract
The median fins of tuna can morph in position and shape to enhance their hydrodynamic performance. Based on the C-turn kinematic equations and the self-propulsion swimming numerical model, the hydrodynamics of the median fins in different morphing forms (erected and depressed forms) are analyzed under the condition of three-degree of freedom (3DoF) self-propulsion, and then the assisted-turning mechanism of the median fins is clarified. The results show that the erected median fins have higher hydrodynamic forces, which can not only increase the yaw speed, but also reduce the turning radius to a certain extent.
The Gutman Index of the Unicyclic Graphs with pendent edges
Authors: Feng Mengmeng , Yu Xiangran , Zhang Jing , Duan Wei 
Published: September 2021

Abstract
The graph-parameters mainly studies vertex degree and distance between unordered vertices. There are many graph-parameters, and this paper mainly focuses on the Gutman index. For the sake of discussion, this paper puts forward the concept of “contribution” based on the relationship between Gutman index of graph and vertex-Gutman index. On this basis, we discussed the Gutman index of unicyclic graph with pendent edges in odd and even parts, and gave the corresponding extremal graphs, which lays a foundation for the study of the Gutman index of other cycle graphs.
A hybrid method for fast and robust topology optimization
Authors: Liao Jingping , Huang Gao , Chen Xuechao , Yu Zhangguo , Huang Qiang , Meng Fei 
Published: September 2021

Abstract
To accelerate the convergence rate and obtain robust optimal results with clear profiles of structural topologies, this paper proposes a hybrid multi-population genetic algorithm (MPGA) and bi-directional evolutionary structural optimization (BESO) method for structural topology optimization. Each element in the design domain is treated as an individual and the elemental sensitivity is taken as the fitness function of one individual. Based on these treatments, MPGA operators, including crossover, mutation, migration and selection, are modified to adapt to compliance minimization problems. Additionally, some key parameters are controlled to guarantee a convergent solution and to solve the structural unconnectivity problem. A case is used to verify the effectiveness and efficiency of the proposed method. The numerical results show that the proposed method is efficient, and compared with the BESO method and combined simple genetic algorithm and BESO method, the proposed method provides a powerful ability in searching for better robust solutions and improving convergence speed.
Research on numerical solution of one-sided monotonic function dichotomy
Authors: Liu Tianshi , Dong Yangmei 
Published: September 2021

Abstract
Aiming at the numerical solution problem of given interval dichotomy, the concept of one-sided monotonic function is proposed, and the unique existence of the solution is proved when the two ends of the function take different signs. Therefore, this significantly relaxes the discrimination conditions and effectively expands the numerical solution range of the dichotomy method. On this basis, it is proved that the one-sided monotonic function is a monotonic function in a relatively small interval containing the zero point. The introduction of the concept of one-sided monotonic function provides a theoretical basis for further expanding the application range of the dichotomy numerical solution, and has certain theoretical and practical significance for dealing with scientific and engineering problems as well as related numerical calculation problems.
Algebraic and Topological Structures of Complex Numbers
Authors: Lv Quanjin , Peng Xinghao , Wu Yuqing , Zhang Jiaying 
Published: September 2021

Abstract
Complex numbers play a fundamental role in every branch of mathematics. First, we review the definition of the complex numbers, discuss their arithmetic operation properties and give proof of the Lagrange identity. At last, we take the investigation of topological notations of the complex plane
Bridge strain denoising method based on variational mode decomposition
Authors: Yang Ming , Cheng Hanjian , Lu Zheyuan 
Published: September 2021

Abstract
In the construction and maintenance of bridge, it is very important to measure the strain of bridge accurately. However, the bridge strain measured in practical engineering is often mixed with a lot of signal noise, how to effectively remove the signal noise is a problem. Variational mode decomposition (VMD) is a denoising algorithm proposed in recent years, which has been applied in some engineering fields. Based on the vehicle bridge coupling theory, the strain of the bridge is obtained by numerical simulation, and the Gauss white noise is added to the strain to simulate the actual engineering situation. Based on VMD theory, a new bridge strain denoising method is proposed, and some key parameters are analyzed. The results of numerical simulation show that the denoising algorithm is effective. For example, when the signal-to-noise ratio of bridge strain data is 10dB, it can be increased to 21.67dB after using VMD denoising algorithm.
Monotonicity Formula On Cigar Soliton
Authors: Wan Ruizhe 
Published: September 2021

Abstract
In this paper, we prove a monotonicity formula on cigar soliton. Using the monotonicity, we obtain a three-ball type theorem. There might be some people who have proved the three-ball theorem on Cigar Soliton before, but we use a new method. We add a weight function in the norm of u. By doing so, we make the calculation process much easier because when using integral by part, the term that integrates at the surface of ball would disappear as the weight function we add would be zero.
Simulation of nozzle flow based on Euler equations
Authors: Chen Kaipeng , Liu Haoze , Tang Yinghan 
Published: September 2021

Abstract
The nozzle is a widely used device in daily life, such as water fountains to rocket engines. It is important to find out the influence of the position of the nozzle throat for the application or the design of the nozzle. To that end, the finite difference method was employed to solve the 1D Euler equations to obtain the flow inside the nozzle. To implement the method, an in-house python code was developed. The relationship among the velocity, pressure and density in the convergent-divergent nozzle flow was found. It is observed that: the velocity rose quickly along with the nozzle and reached the top before a rapid decrease; pressure remained constant initially, which eventually began to drop; density dropped steadily and had a turning point. Moreover, the influence of the nozzle throat position is investigated thoroughly. It is observed that the position of the nozzle throat influences the velocities at the nozzle exit. The faster the flow reaches the throat, the higher the velocity or Mach number at the exit boundary.
A Mechanical Model for Radial Inertial Impact Switch
Authors: Ma Bing , Wu Peng , Wang Sen , Wang Zhen , Xu Pengzhao 
Published: September 2021

Abstract
The traditional inertial impact switch based on experience design often appears in the problem of early closure within the threshold. To solve this problem, a new method of inertial switch design is presented in this paper. Firstly, the force analysis of inertia switch is carried out and a mechanical model is established. Through the model, it is concluded that the closing threshold of inertia switch is related to the spring resistance, the mass and center of mass of contact pole, the spring radius of contact pole and the horizontal projection of the minimum distance between the spring and the reference point. After that, the mechanical model is verified by simulation, and the correctness of the mechanical model is proved. The experimental results show that the proposed model can effectively solve the problem of premature closing of the inertial switch within the threshold and improve the pass rate of the product.
Analysis of the Mainstream Interpretation of Quantum Physics
Authors: Zhang Yitian 
Published: September 2021

Abstract
Quantum physics is changed in an unexpected way. Scientists believe that the study of quantum physics will play an important role in future technology. Therefore, it is meaningful to study quantum physics. The aim of this paper is to provide an initial explanation of the quantum world through the classical single particle double-slit interpretation experiment, and to answer a few questions about the experiment using mainstream quantum mechanical interpretations, such as the Copenhagen interpretation and the Many-Worlds interpretation. The superposition state, which is the core of the Copenhagen interpretation, is then introduced. The Einstein-Podolsky-Rosen paradox and locality are also introduced, and the relationship between the latter and special relativity is analyzed. The author also discusses whether non-locality leads to retrocausality. Finally, the author discusses the relationship between multi-world interpretation and Schrodinger’s cat, but this may raise some philosophical questions. However, realist and hidden variable interpretation are also consistent as long as locality is abandoned.
Design of a Long-stroke Low-frequency Sound Device
Authors: Fang Houlin , Zhang Fang , Li Ao , Zhang Liangyong , Li Pengyi , Liu Yunzhe , Zhang Dezhi 
Published: September 2021

Abstract
In order to improve the radiation performance of low-frequency sound device, a design method for a long-stroke low-frequency sound device is proposed, which mainly involves the design of the drive structure and radiation structure and the drive structure is designed with an electric long stoke. The flat plate and conical structures of piston plate of radiation structure are compared, and a long-stroke radiation structure with a low-damping guide support motion pair uniformly distributed in the circumferential direction is proposed. The numerical simulation results show that, with six straight-line bearings circumferentially and uniformly distributed, the displacement and stress distribution of piston plate are better than those of piston plate with three straight-line bearings installed in the same manner. The sound device is further tested in the experiment, and it is found that the vibration displacement amplitude at the center of piston plate is 3.9 mm (20 Hz), and the maximum sound pressure level of 40 Hz is found at the location 10 m from the center of sound device along the axial direction, reaching 105.3 dB.
Principles, Detections and Applications of Cosmological Gravitational Waves
Authors: Hanhao Chen , Sirou Zhao , Suqing Xie 
Published: September 2021

Abstract
Contemporarily, the gravitational wave has played an important role in the field of astronomy. A systematic review of the gravitational wave is presented in this paper. Primarily, the principle of gravitational waves is introduced in both Newton and Einstein’s concept of gravity. Besides, we deduced the solution of Einstein’s field equation. Moreover, we described the detection of gravitational waves with the mechanisms of the two gravitational wave detectors LIGO and Virgo Finally, the applications of gravitational waves are discussed in detecting black hole mergers, neutron star mergers, gamma-ray burst, and core-Collapse Supernova explosion. The gravitational wave could contribute to more scientific findings in the future and solve more mysteries of the Universe.
The Chaos Theory and its Application
Authors: Su Feier 
Published: September 2021

Abstract
Chaos Theory is not only one of the most active branches of the dynamical system, but also one of the most important topics of the nonlinear scientific field. The main purpose of this thesis is to introduce and illustrate the basic concepts, characteristics, and various applications of Chaos Theory. Chaos Theory is widely applied in physics, biology, and economics fields etc., so the thesis will also exhibit interdisciplinary research on Chaos Theory. The conclusion is that the most important refinement of Chaos Theory is its sensitivity to initial values, and subtle changes will affect the final shape and state of the entire structure.