bluuebunny/crossref_metadata_2025 huggingface dataset:
Constructal optimization of variable cross-section insulation layer of steel rolling reheating furnace wall based on entransy theory
Authors: Feng Hui-Jun  , Chen Lin-Gen  , Xie Zhi-Hui  , Sun Feng-Rui  ,   Institute of Thermal Science and Power Engineering, Naval University of Engineering; Military Key Laboratory for Naval Ship Power Engineering, Naval University of Engineering; College of Power Engineering, Naval University of Engineering, Wuhan 430033, China
Published: December 2020

Based on the entransy dissipation extremum principle for thermal insulation process, the constructal optimizations of a variable cross-sectional insulation layer of the steel rolling reheating furnace wall with convective and compound heat transfer (mixed convective and radiative heat transfer) boundary conditions are carried out. An optimal construct of the insulation layer with minimum entransy dissipation rate can be obtained. Results show that the global thermal insulation performance of the variable cross-sectional insulation layer at minimum entransy dissipation rate is better than that of the constant cross-sectional one. The optimal constructs of the insulation layer obtained based respectively on the minimizations of the entransy dissipation rate and heat loss rate are different. The optimal construct of the insulation layer at minimum heat loss rate leads to a reduction of the energy loss, and that at minimum entransy dissipation rate leads to an improvement of the global thermal insulation performance. The difference between the optimal constructs of the variable cross-sectional insulation layer based on the minimizations of the entransy dissipation rate and the maximum temperature gradient is small. This makes the global thermal insulation performance and thermal safety of the insulation layer improved simultaneously. The constructal optimization of the insulation layer based on entransy theory can provide some new guidelines for the optimal designs of the insulation systems.
Experimental study on screech tone mode switching of supersonic jet flowing through rectangular nozzles
Authors: Chen Zhe  , Wu Jiu-Hui  , Chen Xin  , Lei Hao  , Hou Jie-Jie  ,   School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an 710049, China;,   State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi'an Jiaotong University, Xi'an 710049, China;,   Aeronautics and Astronautics Engineering Institute of Air Force Engineering University, Xi'an 710038, China
Published: December 2020

An experiment was carried out to analyse and compare the screech tone characteristics and schlieren structures of an under-expanded jet flowing through four rectangular nozzles, aspect ratios of which are different (having the same height but different widths), with the jet pressure ranging from 0.2 to 0.8 MPa. Results indicate that there exist two different screech tone modes in the noise generated by supersonic jet flowing through the rectangular nozzles with different aspect ratios, and a mode switching can be found by altering the jet pressure. Mode switching is a phenomenon that different mode dominates or disappears according to the change of jet pressure. The switching time of fundamental frequencies in the screech tone modes and the width of the domination interval would be shortened as the aspect ratio decreases. The jet flow pressure drop interval of one mode, whose aspect ratio is 2, is extremely small. This phenomenon has never been mentioned in the literature. When the aspect ratio of the rectangular nozzle is 4, there exists an interruption and skip on the fundamental frequency-jet pressure curve within the jet flow domination interval for jet pressure at 0.49 MPa. As the pressure reduces, the axes of the schlieren figures begin to shake, and the structure stability of the flow field with different aspect ratio varies with the jet pressure. When the jet pressure is within the range of 0.45 to 0.70 MPa, the density in the first shock-cell decreases as the aspect ratio reduces. Meanwhile, axial pulsation and disorder of the flow field behind the second shock-cell appear. When the jet pressure is under 0.45 MPa, the flow field structure of the shock wave becomes more stable as the aspect ratio increases. In this pressure region, the periodical shock-cell structure is weaker than those above 0.45 MPa. Analyzing the screech frequency spectrum and the schlieren figures, we can find that the second and third shock-cells also have feedback and enhancement for the sound pressure of the screech frequency.
A two-phase turbulence probability density function model in unified colored-noise approximation
Authors: Wang Lu  , Xu Jiang-Rong  ,   School of Energy and Power Engineering, Nanjing University of Sicence and Technology, Nanjing 210094, China;,   Insititute of Energy Science and Engineering, Hangzhou Dianzi University, Hangzhou 310018, China
Published: December 2020

A unified colored-noise approximation (UCNA) method has been widely used to solve the simple one-dimensional problem, and this paper attempts to extend this method to multi-dimensional systems. Firstly, a Fokker-Planck equation is obtained by UCNA method based on the Langevin equation for particle motion, then a two-order moment trajectory model is established on this basis. The new model can be successfully used to predict the backward-facing step two-phase flow, and the simulation results agree well with the measurements. This study shows that the UCNA method is still effective in dealing with multi-dimensional two-phase turbulent systems.
Growth mechanisms of dendrites and eutectics within undercooled liquid Al-Ni alloys
Authors: Yang Shang-Jing  , Wang Wei-Li  , Wei Bing-Bo  ,   Department of Applied Physics, Northwestern Polytechnical University, Xi'an 710072, China
Published: December 2020

Al-4 wt.%Ni (hypoeutectic), Al-5.69 wt.%Ni (eutectic) and Al-8 wt.%Ni (hypereutectic) liquid alloys are highly undercooled and rapidly solidified under free fall condition. Theoretical calculations indicate that the coupled zone of (Al+Al3 Ni) fibrous eutectic is an unclosed region in the composition range from 4.8 to 15 wt.% Ni, which is strongly skewed towards the Al3 Ni phase side. It is found that the cooling rate and undercooling of liquid alloys would increase as the droplet size decreases. Then the microstructural evolution of Al-Ni alloys will be induced by the competitive growth of (Al) dendrite, Al3 Ni dendrite, and (Al+Al3 Ni) eutectic. During the rapid solidification of Al-4 wt.%Ni hypoeutectic alloy, complete solute trapping effect occurs and then causes the formation of metastable segregationless (Al) solid solution phase. When the droplet undercooling exceeds 58 K, the structural morphology of Al-5.69 wt.%Ni eutectic alloy shows a transition from (Al+Al3 Ni) fibrous eutectic to primary phase (Al)-dominated hypoeutectic structure. As the undercooling increases further, the fibrous eutectic becomes the unique microstructure of Al-8 wt.%Ni hypereutectic alloy, and finally evolves into a kind of granular eutectic.
Improved convolution kernel based DFM model for nano-scale circuits
Authors: Yang Yi-Wei  , Zhang Hong-Bo  , Li Bin  ,   Electric Power Research Institute of China Southern Power Grid, Guangzhou 510080, China;,   College of Electronic and Information Engineering, South China University of Technology, Guangzhou 510640, China;,   Synopsys Inc., Oregon 97006, US
Published: December 2020

Limited by materials and process stability, the nano-scale IC manufacturing process is still based on the 193 nm light technology and the wavelength is larger than the feature size of layout, thus the induced interference and diffraction greatly reduce the resolution, which affect the quality of the chip. So the layout needs to be checked by the design-for-manufacturability (DfM) model before manufacturing. Traditional DfM models describe the process steps using physical models, and deduce the convolution kernels by decomposing the matrix in corresponding physical models, which are not only complicated but also hard to use; thus combined with the insufficiency of physical models, it is difficult to describe the process with thousands of parameters. This paper uses convolution form as the framework of DfM model, and deduces the relationship, represented as convolution kernels, between layout and contour by an optimization method. Every element in the convolution kernels is optimized based on the input and output data of the process and is also a dimension to describe the process. This model overcomes the disadvantages of the traditional model which needs confidential information such as process parameters, and it has more powerful capability to describe the process. Moreover, the model can contain the layout correction information, and describe the process from layout to contour. Experiment results for 65 nm process show that the model has an accuracy of 8 nm.
A half-covered helical cone-beam reconstruction algorithm based on the Radon inversion transformation
Authors: Han Yu  , Li Lei  , Yan Bin  , Xi Xiao-Qi  , Hu Guo-En  ,   National Digitial Switching System Engineering and Technological Research Center, Zhengzhou 450002, China
Published: December 2020

Compared with the traditional helical cone-beam computed tomography (CT), the field-of-view (FOV) half-covered cone-beam CT can almost double the FOV and thus image the large object by using a smaller panel detector. However, the projections are transversely truncated, resulting in truncation errors in reconstructed images if no correction measures are taken. In this paper, a half-covered cone-beam reconstruction algorithm based on the Radon inversion transformation is developed, in which the data filtering is performed in two steps. The first step is a local operation and can be carried out correctly even when the data is truncated. This performance of local operation makes the original data closer to zero, so the continuity of data is improved. And this also can restrain the truncation errors caused by the following global operation. Numerical simulations and experimental results are presented to demonstrate the algorithm and to compare it with existing algorithms. Preliminary results indicate that the proposed algorithm can well restrain the truncation errors and improves reconstruction quality.
3D micro/nano fabrication and its application in cancer biophysics
Authors: Lu Jin-Lei  , Wang Xiao-Chen  , Rong Xiao-Hui  , Liu Li-Yu  ,   Laboratory of Soft matter, Institue of Physics Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

The major reason why cancer kills is its metastatic potentials. Metastasis is an extremely complex three-dimensional (3D) process. Currently, routine in vivo cancer research still experiences bottlenecks in observation and manipulation, while in vitro research mainly stays in petri-dish levels that limit cell environment with two-dimensional confinements. Therefore, it is in urgent needs to construct 3D in vitro models to deepen the studies in cancer invasion and metastasis. However “how to carry out” is a big question that harasses scientists for decades. In this report, we will systematically discuss several popular technologies for 3D microfabrication and their applications in bio and cancer research. Besides, we will demonstrate our efforts to construct an all-in-one 3D micro ecology simulation system (3D MESS) which highly integrates a UV bio-compatible hydrogel printer, a light-sheet imaging system, and a nano pipette operation system. This novel system will create a brand-new method to fabricate, observe and controls the 3D structures and the cells inside. We believe that these advanced technology and ambitions will definitely update the current cancer research methods and bring promising hopes for future deeper understandings and more efficient treatment of cancer.
Ranking key nodes in complex networks by considering structural holes
Authors: Han Zhong-Ming  , Wu Yang  , Tan Xu-Sheng  , Duan Da-Gao  , Yang Wei-Jie  ,   Beijing Technology and Business University, Beijing 100048, China
Published: December 2020

Structural hole nodes in complex networks play important roles in the network information diffusion. Unfortunately, most of the existing methods of ranking key nodes do not integrate structural hole nodes and other key nodes. According to the relevant research on structural hole theory as well as the key node ranking methods, network constraint coefficient, betweenness centrality, hierarchy, efficiently, network size, PageRank and clustering coefficient, 7 metrics are selected to rank the key nodes. Based on the 7 metrics, a ranking learning method based on ListNet is introduced to solve ranking key nodes by multi metrics. Comprehensive experiments are conducted based on different artificial networks and real complex networks. Experimental results with manual annotation show that the ranking method can comprehensively consider the structural hole nodes and other nodes with different important features. The ranking results on different networks are highly consistent with the manual ranking results. The spreading experiment results using signed to interference ratio propagation model show that SIR model can reach a maximum propagating ratio in a shorter propagating time initiated by TOP-K key nodes selected by our method than TOP-K key nodes selected by other methods.
Study of energy partitioning and its feedback on the microclimate over different surfaces in an arid zone
Authors: Li Hong-Yu  , Fu Cong-Bin  , Guo Wei-Dong  , Ma Fang  ,   Institute for Climate and Global Change Research, School of Atmospheric Sciences, Nanjing University, Nanjing 210093, China;,   Environmental Institute, International Cooperation Center of National Development and Reform Commission Urban Planning and Design Institute, Beijing 100045, China
Published: December 2020

Model simulations show that land use and land cover changes(LUCC) may alter surface energy budget and influence surface microclimate, but up to now, it still lacks of sufficient observations for explaining the mechanism of climate change brought about by LUCC. Grasslands and shrub lands are typical land covers in the mid-latitude arid zone of the northern hemisphere. The data used in this paper was collected from four sites which are related to grassland, open shrubland, savanna and closed shrubland, and all located in New Mexico, USA. The four sites are near each other and have the same background in climate and weather. Thus, the difference in surface energy partitioning over the four surfaces is induced by different land processes, which was explained in our study. The paper also analyzed the feedbacks of different land surface parameters and energy partitioning for the surface microclimate.We find that the leaf area index(LAI) and surface roughness of the four sites increases from the desert grassland to the closed shrubland. The difference in vegetation structures and functions also affects aerodynamic resistance and surface resistance to heat transfer and the resistances exhibit larger over sparse surfaces. Generally, the sites with high vegetation cover have higher net radiation, sensible and latent heat fluxes, particularly in the growing season. In addition, the contributions of impacting factors to the turbulent fluxes are diagnosed by Penman-Monteith equation and a mathematical formula combining net radiation with Bowen ratio. Compared to the desert grassland, the variations in net radiation over other three surfaces indicate positive contributions to both sensible and latent heat fluxes and govern their changes. The variations in the aerodynamic resistance and the surface resistance lead to opposite contributions. Besides, both radiative surface temperature and surface air temperature over the sparse surfaces are significantly higher than that over the closed shrubland. Larger aerodynamic resistance and Bowen ratio over the sparse vegetation dominate the warming trend accompanying the vegetation degradation and simultaneously offset the cooling effect induced by the decrease in net radiation, showing the land surface process over different surfaces factually has an evident feedback on surface micro-climate in the same climate and weather background.
A new fast algorithm based on compressive sensing for composite electromagnetic back scattering from a 2D ship located on a 1D rough sea surface
Authors: Chai Shui-Rong  , Guo Li-Xin  ,   School of Physics and Optoelectronic Engineering, Xidian University, Xi'an 710071, China
Published: December 2020

As one of the most popular numerical methods, the method of moments (MoM) is known for its high accuracy. Besides, MoM has other advantages. For example, the integral equations satisfy the Sommerfeld radiation condition automatically, the additional boundary conditions are not needed., etc. But if the wide angle problem, especially the composite electromagnetic back scattering from a ship place on sea surface, is considered, the MoM needs to solve the integral equation at every incident angle, which needs a large calculating quantity, and is time consuming. To solve this problem, a new efficient method based on the compressive sensing and the MoM is proposed and validated in this paper. A new incident source derived through multiplying the transform matrix by the voltage matrix is first introduced. And then the measurements of the induced currents can be obtained by solving the integral equation under the new incident source. Finally the original electromagnetic currents can be recovered by using the recovery algorithms (the orthogonal matching pursuit is used in this paper). The validity and the efficiency of the new method are demonstrated by comparing with the traditional MoM.
Magnetic force of piezoelectric cantilever energy harvesting system with an externally applied magnetic field based on magnetizing current method
Authors: Tan Dan  , Leng Yong-Gang  , Fan Sheng-Bo  , Gao Yu-Ji  ,   School of Mechanical Engineering, Tianjin University, Tianjin 300072, China;,   Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin 300072, China
Published: December 2020

This paper focuses on the piezoelectric cantilever energy harvesting system with an externally applied magnetic field. The calculation method and model for the magnetic force are proposed from the magnetizing current method, and the calculation results are compared with a set of experimental data. The study shows that there is a deviation in the calculation model derived by the magnetizing current method, which increases as the distance between two magnets decreases. The calculation model is improved by introducing the deflection angle of the magnet at the end of the cantilever beam, and is reliable to calculate the magnetic force of piezoelectric cantilever energy harvesting system with an externally applied magnetic field for further studying this energy harvesting system.
Diffusion denoising model based on the wavelet and biharmonic equation
Authors: Zhou Xian-Chun  , Wang Mei-Ling  , Shi Lan-Fang  , Zhou Lin-Feng  ,   College of Electronic and Information Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   Jiangsu Key Laboratory of Meteorological Observation and Information Processing, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   College of Mathematics and Statistics, Nanjing University of Information Science and Technology, Nanjing 210044, China
Published: December 2020

In image processing, in order to well preserve corners, peaks, and thin edges of the image, a new biharmonic diffusion model is established, which takes into account the stress balance of the biharmonic equation and local maximum values of higher-order partial derivatives. If the noise is very strong in the image, some isolated spots will leave on the processed image, and texture of the image has statistical properties in a large range, and the new model retains only local details, the information of image in a wide range is not kept well. Further improvement on the above model is made by using the wavelet transform to extract the high frequency part of the image, and by processing this part with stress balance to establish wave field biharmonic diffusion model, which stably controls the image details locally. Analysis and simulation results show that this model retains more image information than the Perona-Mailik model, effectively well preserves the edges, corners, peaks of the image, and also maintains thin edges of the image. So it is an ideal model.
Amplification without population inversion in tree-level system driven by an additional microwave field
Authors: Yang Li-Jun  , Ma Teng  , Sun Ke-Jia  , Feng Xiao-Min  ,   College of Physics Science and Technology, Hebei University, Baoding 071002, China
Published: December 2020

In this paper, we investigate the spectrum properties of the lasing without population inversion in a three-level atomic system under an action of an externally applied microwave field. The probed absorption spectrum is obtained by solving the density matrix equation of this system. The results show that the absorption profile has a multi-peak structure, and exhibits obviously negative absorption (light amplification) in a specific range under the action of strong microwave field. The characteristic of the light amplification without population inversion according to the three level atomic system is demonstrated by the quantitative analysis of populations related to the probe levels.
Resonant modes in photonic double quantum well structures with single-negative materials
Authors: Kang Yong-Qiang  , Gao Peng  , Liu Hong-Mei  , Zhang Chun-Min  , Shi Yun-Long  ,   Institute of Solid State Physics, Shanxi Datong University, Datong 037009, China;,   Department of Physics, Xi'an Jiaotong University, Xi'an 710049, China;,   Tsingtao University of Science and Technology, College of Mathematical and Physical Sciences, Qingdao 266061, China
Published: December 2020

The transmission spectra of the model of photonic double quantum well consisting of two photonic crystals with two different single-negative materials are calculated by the transfer matrix method. It is found that these resonance modes split into pairs, owing to a coupling between two photonic wells. The distance of resonant modes can be controlled by the coupling strength between the two wells. It is observed that when two photonic quantum wells are far from each other, resonance modes appear as single peak. And the quality factors of the transmittance resonance peaks can be greatly improved by increasing the period number of outer barriers. The resonance modes are affected weakly by the incident angle and polarization. The effects of the losses coming from epsilon-negative and mu-negative materials on the resonance modes are also specifically explored, respectively.
Mode division multiplexing of two-dimensional triangular lattice photonic crystal based on magneto-optical effect
Authors: Zhou Wen  , Chen He-Ming  ,   Department of Opto-Electronics, Nanjing University of Posts and Telecommunications, Nanjing 210023, China;,   Department of Bell, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
Published: December 2020

With the rapid development of all-optical communication, the wavelength division multiplexing transmission system cannot meet the requirements of high capacity in optical networks, while mode division multiplexing uses the limited stability modes as independent channels to transmit information, improving the system capacity and spectrum efficiency, which is one of the key technologies in the construction of future optical network. In this paper, a mode division multiplexer of two-dimensional triangular lattice photonic crystal in 1.55 μm band based on the magneto-optic effect of Bi-doped compound rare earth iron garnet bulk single crystal is proposed. The defects of TbYbBiIG medium are introduced as mode splitting waveguides in photonic crystal, of which the permeability changes with the applied magnetic field in different polarization modes. Therefore, mode division multiplexing in 1.55 μm band can be achieved by controlling the propagations of TE and TM mode. The band and transmission characteristics of this device can be analyzed by using the plane wave expansion and finite difference time domain method. The results show that the transmission rates of TE and TM modes both exceed 92% and channel segregation degrees reach 19.7 dB and 42.1 dB respectively. These features indicate the important application prospect in the future high-capacity optical transmission system.
Transmission and control of bright solitons in parity-time symmetric waveguide
Authors: Dang Ting-Ting  , Wang Juan-Fen  , An Ya-Dong  , Liu Xiang-Lian  , Zhang Zhao-Xia  , Yang Ling-Zhen  ,   College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
Published: December 2020

Based on the theoretical model of optical wave propagation in parity-time (PT) symmetric waveguide, the transmission and control of bright solitons in PT symmetric Kerr nonlinear planar waveguide with Gaussian distribution are studied numerically. The PT symmetric waveguide requires that the refractive index distribution of waveguide should have to be an even symmetry, whereas the gain/loss distribution should be odd. The results show that when the strength of refractive index distribution of waveguide is positive, the refractive index has a maximum value in the center of the PT symmetric waveguide. Without the self-focusing Kerr nonlinear effect, the waveguide can also restrict optical wave to form the wavy light beam and transmit with long distance. When the strength of refractive index distribution is negative, the refractive index has a minimum value in the center of the PT symmetric waveguide. The transmission direction of optical wave is shifted. The gain/loss distribution can control the transmission direction of optical wave: if the strength of gain/loss distribution is positive, the optical wave is shifted toward the left; if the strength is negative, the optical wave is shifted toward the right; if the strength equals zero, the optical wave is divided into two beams. And when the refractive index distribution is negative, the interaction between adjacent bright solitons can be suppressed very well. The results of this research can provide a theoretical basis for the application of PT symmetric waveguide in all-optical control in the future.
Sparse channel estimation of underwater acoustic orthogonal frequency division multiplexing based on basis pursuit denoising
Authors: Yin Yan-Ling  , Qiao Gang  , Liu Song-Zuo  , Zhou Feng  ,   Acoustic Science and Technology Laboratory, Harbin Engineering University, Harbin 150001, China;,   College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

To solve the problem of poor performance of the traditional l2-norm channel estimation, a sparse channel estimation approach based on basis pursuit denoising (BPDN) is proposed in orthogonal frequency division multiplex underwater acoustic communication. Owing to the sparsity of the underwater acoustic channel, only a few observations are needed to recover the channel impulse response with a high accuracy. Compared with greedy pursuit algorithm, BPDN algorithm has the globally excellentest solution. The signal is estimated based on the l2-l1 norm rule and the observations containing the noise are considered. The regularization parameter can be changed to balance the signal's sparsity against the residual error. The influences of the pilot distribution and the regularization parameter on the BPDN algorithm are discussed in the simulation. The BPDN channel estimator is compared with the least square (LS) and also with orthogonal matching pursuit (OMP). The data collected from lake experiment show that the BPDN channel estimator outperforms the LS and OMP channel estimator over spare underwater acoustic channel.
Chaos of a kind of nonlinear relative rotation system based on the effect of Coulomb friction
Authors: Liu Shuang  , Tian Song-Tao  , Wang Zhen-Chen  , Li Jian-Xiong  ,   Key Laboratory of Industrial Computer Control Engineering of Hebei Province, Yanshan University, Qinhuangdao 066004, China;,   National Engineering Research Center for Equipment and Technology of Cold Rolling Strip, Qinhuangdao 066004, China
Published: December 2020

Chaotic motion of a kind of nonlinear relative rotation system with load Coulomb frictional damping is investigated. Based on the Lagrange equation of a dissipative system, the dynamic equation of a kind of nonlinear relative rotation system with two pieces of mass is established, which contains a kind of nonlinear load Coulomb frictional damping. The eigenvalue of the autonomous system is discussed using Cardano formula. On this basis, the existence of homoclinic orbits is given by the undetermined coefficient method, and the chaotic motion of the system is investigated by means of Silnikov theorem. Finally the chaotic motion of the system with the known parameters is studied numerically. With the variation of Coulomb frictional damping, a route to chaos through period-doubling bifurcations is exhibited. Numerical calculation can confirm the validity of the analytical results.
Calculation of equation of state of a material mixture
Authors: Zhou Hong-Qiang  , Yu Ming  , Sun Hai-Quan  , He An-Min  , Chen Da-Wei  , Zhang Feng-Guo  , Wang Pei  , Shao Jian-Li  ,   Institute of Applied Physics and Computational Mathematics, Beijing 100094, China
Published: December 2020

The problem of calculating the equation of state (EOS) of a material mixture often comes from fluid-dynamical system containing multiple materials. Generally, the EOS of a material mixture is a system of nonlinear equations which are usually solved by the tabular method and the Newton iterative method. However, the former has poor accuracy, and the later has a finite radius of convergence and hence will converge only if the initial guess is sufficiently close to the final solution. So, a procedure different from the above two method is presented for calculating the EOS of a material mixture whose constituents are in pressure equilibrium and temperature equilibrium. An imbedding method is used to determine the constituent partial thermodynamic variables subjected to the constraints that the total volume and energy of mixture and the constituent mass fractions are specified. The imbedding method has a large radius of convergence, introducing a parameter defined in the interval [0, 1] and a system of imbedding equations which is linearly composed of the to-be-solved EOS of a material mixture and the easy-to-solve EOS of a material mixture. While the parameter changes continuously from 0 to 1, the imbedding method continuously changes the solution of the to-be-solved EOS which the easy-to-solve EOS of a material mixture is continuously converted into. The system of imbedding equations can be changed into a system of ordinary differential form by taking the parameter as independent variable, easily solved by a matured computational method such as trapezoidal rule. By using thermodynamic formulae, two equations in the generalized Maxwellian form are obtained, relating respectively the pressure rate and temperature rate to the strain rate and the constituent mass fraction rate. Finally, the computational method is verified by calculating the EOS of various mass fractions of lead and tin mixture.
Motion of the nanodrops driven by energy gradient on surfaces with different microstructures
Authors: Zhang Kai  , Lu Yong-Jun  , Wang Feng-Hui  ,   Department of Engineering Mechanics, Northwestern Polytechnical University, Xi'an 710129, China
Published: December 2020

In recent years, the motion of nanodroplets on energy gradient surface on a microscale has attracted widespread attention, however, experimental studies are still irrealizable. In this work, the motions of nanodroplets driven by the energy gradient on surfaces with different microstructures are studied by molecular dynamics method. The results show that: the groove-shaped and post-shaped microstructures can remarkably enhance the motion efficiency of the nanodroplets, while the nail-shaped microstructures decrease the motion efficiency, despite they can achieve a stable hydrophobicity. The hybrid microstructures composed of groove-shaped and nail-shaped textures inherit both the advantages of the two microstructure, which not only enhances the motion efficiency of nanodroplets, but also increases the hydrophobic stability. Furthermore, small change in surface energy can significantly affect the velocity of nanodroplet.
Study on thermodynamics basic and alloy phase evolution of Mg-Sn-Si magnesium alloy
Authors: Zhang Jian-Xin  , Wang Hai-Yan  , Gao Ai-Hua  , Fan Shi-Ke  ,   Institute of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, China;,   Institute of Liberal Arts and Law, Henan Polytechnic University, Jiaozuo 454000, China;,   Institute of Mechanical and Power Engineering Henan Polytechnic University, Jiaozuo 454000, China
Published: December 2020

Thermodynamics basic and alloy phase evolution of Mg-Sn-Si alloy are studied. The results indicate that for Mg-Sn-Si alloy, the specific heat of alloy phase increases with temperature, and it changes quickly at low temperature while gently at high temperature. In the range of low temperature, its thermal expansion increases exponentially with the increase of temperature, and in the range of high temperature the thermal expansion increases linearly. In the two structures of Mg2 (Six, Sn1-x) and Mg2 (Snx,Si1-x) phases, the replacement position of Si or Sn is indefinite, they could be face-center location or vertex location. Under the conditions of conventional solidification, the range of values for x is fluctuant, for it is in nonequilibrium state: x values are around 0.25 and 0.75 for Mg2(Six, Sn1-x) and Mg2(Snx, Si1-x) structure, respectively. The generation temperature of Mg2 (Si, Sn) phase is quite high, it can be precipitated directly from liquid phase, or be transformed from Mg2Si. The generation temperature of Mg2(Sn, Si) phase is lower than that of Mg2(Si, Sn), and it can be precipitated only from the matrix, the initial precipitation temperature of Mg2(Sn, Si) tends to rise with Sn content increasing.
Effect of In–2N heavy co-doping and preferred orientation on the optical band gap and absorption spectrum of ZnO
Authors: Hou Qing-Yu  , Li Wen-Cai  , Zhao Chun-Wang  ,   College of Sciences, Inner Mongolia University of Technology, Hohhot 010051, China
Published: December 2020

Nowadays although the In–N co-doping effects on the optical band gap and absorption spectrum of ZnO are studied extensively, all of the In–N co-doped ZnO materials are of random doping, and the preferred orientation doping using the unpolarized structure of ZnO has not been considered so far. Therefore, in this paper, based on the density functional theory using first principles plane-wave ultrasoft pseudopotential (GGA+U) method, the densities of states and absorption spectra of un-doped and the In–N heavily co-doped Zn1-xInxO1-yNy (x= 0.0625-0.03125, y=0.0625-0.125) in different orientations are calculated. The results show that in the same doping mode, the larger the volume of doping system, the higher the total energy and the formation energy are and the narrower the optical band gap is; the red shifting of absorption spectrum becomes more significant with the increase of In–2N co-doping amount. Those are in good agreement with the experimental results. Under the condition of different doping manners and the same In–2N co-doped concentration, the co-coped In–N atoms along the c-axis orientation, have the narrower optical band gap and more significant red shifting of absorption spectrum than the In–N atoms with the orientation perpendicular to the c-axis. We believe that these results may be helpful for designing and preparing the new photocatalyst materials of In–N heavily co-doped ZnO.
Negative refraction and bulk polariton properties of the graphene-based hyperbolic metamaterials
Authors: Gong Jian  , Zhang Li-Wei  , Chen Liang  , Qiao Wen-Tao  , Wang Jian  ,   School of Physics and Chemistry, Henan Polytechnic University, Jiaozuo 454000, China;,   School of Civil Engineering, Henan Polytechnic University, Jiaozuo 454000, China
Published: December 2020

We theoretically investigate the electromagnetic properties of the multilayer graphene-dielectric composite materials based on the effective medium theory. It is found that the structure exhibits hyperbolic isofrequency wavevector dispersions at THz and far-infrared frequencies, hence thereby realizing the effective graphene-based hyperbolic metamaterials (HMM). The frequncy band of the hyperbolic dispersion can be tuned by changing the Fermi energy of graphene sheet, the thickness of the dielectric layer and the layer number of graphene sheets. Because of the hyperbolic dispersion, graphene-based HMM possesses a negative energy refraction and positive phase refraction for oblique incidence at far below the critical frequency. The highly confined bulk polariton modes are also supported. Based on the attenuated total reflection configuration, the excitation of the bulk polariton mode is studied, in addition, such properties used in the tunable optical reflection modulation are also explored.
A model of capacitance characteristic for uniaxially strained Si N-metal-oxide-semiconductor field-effect transistor
Authors: Lü Yi  , Zhang He-Ming  , Hu Hui-Yong  , Yang Jin-Yong  , Yin Shu-Juan  , Zhou Chun-Yu  ,   Key Laboratory for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an 710071, China;,   Beijing Research Institute of Precise Mechatronic Controls, Beijing 100076, China;,   College of Science, Beijing Information Science and Technology University, Beijing 100192, China
Published: December 2020

The capacitance model is fundamental for the transient analysis, AC analysis and noise analysis of uniaxially strained Si MOSFET device and circuit. Firstly, the 16-differential capacitance model for uniaxially strained Si NMOSFET is developed. Secondly, the simulation results from that model match the experimental results well, which validates the accuracy of the model. Meanwhile the simulated relations of key gate capacitance Cgg to stress intensity, bias voltage，channel length and concentration of poly gate are obtained and analyzed, showing that the value of Cgg is a little larger than that of strainless bulk device while the changing tendency keeps the same.
Magnetic and transport properties of perovskite manganites (La1-xGdx)4/3Sr5/3Mn2O7 (x=0, 0.025) polycrystalline samples
Authors: Wang Zhi-Guo  , Xiang Jun-You  , Xu Bao  , Wan Su-Lei  , Lu Yi  , Zhang Xue-Feng  , Zhao Jian-Jun  ,   Key Laboratory for Magnetism and Magnetic Materials of Inner Mongolia, Department of Physics, Baotou Normal University, Inner Mongolia University of Science and Technology, Baotou 014030, China;,   Inner Mongolia Key Laboratory for Utilization of Bayan Obo Multi-Metallic Resources, Elected State Key Laboratory, Inner Mongolia University of Science and Technology, Baotou 014010, China
Published: December 2020

The polycrystalline samples of two-layered perovskite manganites (La1-xGdx)4/3Sr5/3Mn2O7 (x=0, 0.025) are prepared by traditional solid state reaction method. X-ray diffraction measurements show that both samples are of the Sr3Ti2O7 -type tetragonal phase (space groups I4/mmm). Magnetic measurements show that Gd3+ doping reduces the magnetic transition temperature (TC3D) and magnetization (M) of the doped sample (La0.975Gd0.025)4/3Sr5/3Mn2O7, which is because Gd3+ doping induces lattice distortion and change the lattice constant, and subsequently weakens the double exchange interactions. It is found from electron spin resonance measurements that short-range ferromagnetic clusters appear in the paramagnetic background of both samples at temperatures TC3DTTC3DT0.975Gd0.025)4/3Sr5/3Mn2O7 has a higher resistance. This is because Gd3+ doping reduces the localization length of carriers, and makes conducting carriers absorb more energy to overcome the bound potentials in the lattice.
Effects of high magnetic field on the growth and magnetic properties of Fe-Ni nano-polycrystalline thin films with different thickness values
Authors: Cao Yong-Ze  , Wang Qiang  , Li Guo-Jian  , Ma Yong-Hui  , Sui Xu-Dong  , He Ji-Cheng  ,   Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819, China
Published: December 2020

The Fe-Ni nano-polycrystalline thin films of 21 nm and 235 nm in thickness are prepared by molecular beam vapor deposition in the absence and the presence of a magnetic field as high as 6 T. The results show that in the absence of the magnetic field, the 21-nm-thick thin films are formed by the grain stacks, and the sizes of grains are about 6-7 nm. In the presence of 6 T, the 5-nm-thick flat layers of interconnected grains of 21-nm-thick thin films are first formed on the surfaces of the substrates, and the grains are then elongated along the surfaces of substrates. Later on, the 21-nm-thick thin films are formed by 6-7 nm-size-grain stacks. In the absence of the magnetic field, the average grain size of the 235-nm-thick thin film is 3.6 nm in the early growth stage, and it is 5.6 nm in the middle growth stage. The growth way of thin film is akin to columnar growth in the final growth stage, and the grains are elongated along the growth direction. In the presence of 6 T, the 5-nm-thick flat layers of interconnected grains of 235-nm-thick thin films are also formed on the surfaces of the substrates, and the grains are elongated along the surfaces of substrates. Later on, the 235-nm-thick thin films are formed by about 6.1-nm-size-grain stacks. Accordingly, the coercive forces in the out-of-plane and in the in-plane of thin films of different thickness values decrease by the 6 T magnetic field.
Magnetic structures, magnetic domains and topological magnetic textures of magnetic materials
Authors: Zhang Zhi-Dong  ,   Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
Published: December 2020

This article first gives a brief review of magnetic structures, magnetic domains and topological magnetic textures and their relations. On the one hand, the magnetic domains are determined by the magnetic structures, the intrinsic magnetic properties and the micro-structural factors of a material. On the other hand, the magnetic domains could control the magnetization and demagnetization processes and also the technical magnetic properties of a material. Topology is found to have a close relation with physical properties of material. Recent interest has focused on topological magnetic textures, such as vortex, bubble, meron, skyrmion, and it has been found that the topological behaviors of these topological textures are closely related with magnetic properties of a material. Then this article introduces recent advances in magnetic structures, magnetic domains and topological magnetic textures, from views of the size effect, defects and interfaces. Finally, this article reviews briefly some results of investigation on the relations between microstructures, magnetic domains and magnetic properties of rare-earth permanent magnetic thin films, the topological magnetic textures and their dynamic behaviors of exchange coupled nanodisks. It has been concluded from the reviews on the literature that the investigation on anisotropic exchange-coupled rare-earth permanent magnets with high performance benefits the high efficient utilization of rare-earth resources. One could achieve optimal magnetic properties through magnetic domain engineering by adjusting the microstructures of magnetic materials. The concepts of topology is applied to various research fields, while the contributions from topological behaviors to physical properties are discovered in different materials. The researches on magnetic domains, topological magnetic ground state and excitation states and their dynamic behaviors are very important for a better understanding of quantum topological phase transitions and other topological relevant phenomena. It can be quite helpful for understanding the correlation between different topological states and their relationship with magnetic properties of a material, and also it will definitely contribute to the applications in various fields of magnetic materials.
Effect of Pt NPs in the film on the performances of ZnO-based metal-semiconductor-metal structured ultraviolet photodetector
Authors: Pei Jia-Nan  , Jiang Da-Yong  , Tian Chun-Guang  , Guo Ze-Xuan  , Liu Ru-Sheng  , Sun Long  , Qin Jie-Ming  , Hou Jian-Hua  , Zhao Jian-Xun  , Liang Qing-Cheng  , Gao Shang  ,   School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, China
Published: December 2020

In this paper, by a radio frequency magnetron sputtering equipment, the ZnO/Pt nanoparticles/ZnO thin film structure is fabricated on a SiO2 substrate via three-step. And the metal-semiconductor-metal (MSM) structured ultraviolet (UV) photodetectors are built up. It is studied that the Pt nanoparticles in different depths of the layer of ZnO thin film affect the photoresponse performances of the MSM ultraviolet photodetector. The results show that the responsivity of the detector increases as Pt nanoparticles in ZnO thin film layers augment with the depth increasing. The responsivity of device is measured under 60 V bias, its photoresponse peak is at 365 nm, and the peak photoresponse is 1.4 A·W-1, which is enhanced by 7 times that of the photodetector without Pt NPs. Considering the performance analyses of ZnO films and the photodetectors, it is clear that the excellent performances of the detector with Pt NPs in the film can result from the scattering of Pt NPs.
Applications of random balance design Fourier amplitude sensitivity test and extended Fourier amplitude sensitivity test in the parameter sensitivity analysis of land surface process model
Authors: Li Hong-Qi  ,   Numerical Weather Prediction Center, China Meteorological Administration, Beijing 100081, China
Published: December 2020

In this paper, we discuss the applications of random balance design Fourier amplitude sensitivity test (RBD-FAST) and extended Fourier amplitude sensitivity test (EFAST) in the parameter sensitivity analysis of land surface process model. We use the common land model and data of Tongyu station, which is a reference site of CEOP in the semi-arid regions, use five model outputs (sensible heat flux, latent heat flux, surface temperature, temperature of air at 2 m over surface, moisture of air at 2 m over surface) as focus output, and use 11 model parameter (soil depth, the soil proportion of 1-5 layers of soil, the porosity of soil, the max dew depth, the roughness of the air between surface and the canopy, and the drag coefficient under the canopy) as the parameters to be analyzed. After the 10 RBD-FAST experiments, we obtain the first-order sensitivity results, and we gain not only first-order sensitivity but also the total sensitivity after the EFAST experiment. The first-order results of two methods show their consistency. The RBD-FAST takes less computing time and is easy to implemente, while the EFAST also has a more comprehensive and reasonable total sensitivity result. All results above illustrate the applications of both RBD-FAST and EFAST in the parameter sensitivity analysis of land surface model. Researchers can choose the suitable one to solve the different problems.