bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of the post-gate annealing on the gate reliability of AlGaN/GaN HEMTs
Authors: Chen Changxi , Wang Quan , Li Wei , Wang Qian , Feng Chun , Jiang Lijuan , Xiao Hongling , Wang Xiaoliang
Published: September 2021

In this paper, we investigated the effect of post-gate annealing (PGA) on reverse gate leakage and the reverse bias reliability of Al0.23Ga0.77N/GaN high electron mobility transistors (HEMTs). We found that the Poole–Frenkel (PF) emission is dominant in the reverse gate leakage current at the low reverse bias region (V
th < V
G < 0 V) for the unannealed and annealed HEMTs. The emission barrier height of HEMT is increased from 0.139 to 0.256 eV after the PGA process, which results in a reduction of the reverse leakage current by more than one order. Besides, the reverse step stress was conducted to study the gate reliability of both HEMTs. After the stress, the unannealed HEMT shows a higher reverse leakage current due to the permanent damage of the Schottky gate. In contrast, the annealed HEMT shows a little change in reverse leakage current. This indicates that the PGA can reduce the reverse gate leakage and improve the gate reliability.
Coupled-ridge waveguide quantum cascade laser array lasing at λ ~ 5 µm
Authors: Yang Pengchang , Zhang Jinchuan , Gu Zenghui , Liu Chuanwei , Zhao Yue , Cheng Fengmin , Zhai Shenqiang , Zhuo Ning , Liu Junqi , Wang Lijun , Liu Shuman , Liu Fengqi
Published: September 2021

In this work, we demonstrated high-power quantum cascade laser (QCL) arrays lasing at λ ~ 5 µm by employing an optimized coupled-ridge waveguide (CRW) structure. Five-element QCL arrays were simulated and fabricated through a two-step etching method to extend the CRW structure to a mid-wave infrared regime. A lateral far-field with the main peak near a diffraction-limited intensity curve of about 10° was observed by properly designing a geometric shape of the ridges and interspaces. By introducing a buried 2nd-order distributed feedback (DFB) grating, substrate emission with a radiation power above 1 W at 25 °C is achieved. Single longitudinal mode operation is obtained by changing the temperature of the heatsink with a good linear wavelength tuning coefficient of –0.2 cm–1/K.
Pore-network distribution laws of cementitious materials detected by high-energy X-ray computed tomography imaging system
Authors: Lyu Qifeng , Guo Yanwei , Chen Anguo , Jia Jie
Published: September 2021

Pore networks of cementitious materials determine the materials’ properties and engineering safety. In this work, four kinds of cementitious materials which are geopolymer cement, foamed cement, ordinary concrete and pervious concrete were prepared, and a high-energy X-ray computed tomography imaging system was used to detect the samples’ inner structures. It was found that the pore network of such materials show similarity to social networks. However, the traditional mathematical degree which is the coordination number of a network is insufficient to characterize the pore networks, because such networks have volume limitations. Thus a new parameter, physical degree, was proposed in this work. By analyses of the pore networks of the samples, it was found the mathematical degrees follow Poisson distribution law whereas the physical degree can be fitted by power law. This indicates the pore networks are random and scale free. These findings may provide insight for future intelligent design of digital cementitious materials.
Finite Element Analysis on Hysteretic Behavior of H-shaped Columns of Thin-Walled Sections of 690 MPa High Strength Steel
Authors: Chen Zhongqi , Feng Wei , Guo Ruipeng , Liu Chunfeng
Published: September 2021

High strength steel is widely used in engineering, especially in light steel structures. However, due to the material properties of high strength steel, its seismic performance has attracted wide attention. To study the hysteretic behavior of H-shaped members of thin-walled sections of Q690 high strength steel, a finite element model was built up by using the general finite element analysis software ABAQUS. Based on the finite element model, an extensive parametric analysis of H-shaped members of thin-walled sections of Q690 high strength steel was carried out. The results showed that the limiting flange width-thickness ratio and web height-thickness ratio for H-shaped members of Q690 high strength steel were recommended to be 11 and 65, respectively, in actual engineering. Also, an increase in web height-thickness ratio and axial compression ratio could lead to a significant decrease in the ductility of H-shaped members of thin-walled sections of Q690 high strength steel. The thinner and more flexible the section is, the larger the axial compression ratio is, further reducing the energy dissipation ability of the members.
Mechanism experimental study on flooding control of Soft Microgel by low-field nuclear magnetic resonance
Authors: Ye Yinzhu , Wu Xingcai , Huang Zhuowei , Bi Taifei , Yang Zhe , Wang Xiaocong , He Lipeng , Liu Yang , Li Shichao
Published: September 2021

The research method of LF-NMR(low field nuclear magnetic resonance) combined with core displacement device has become important experiment was used to study the Water Flooding SCT(swept control technology by water flooding) of soft microgel. Besides, the transverse relaxation time spectrum and the “visual” evaluation method based on LF-NMR were used to investigate the microscopic mechanism of expended sweep volume of soft microgel in single core experiment. The displacement conformance effect of flexible microgel in parallel double-core and its displacement mechanism at different pore scales were analyzed by transverse relaxation time spectrum. The results of single core experiments show that the soft microgel can expand the sweep volume, mainly in the relatively large pore throat, with 15.43%. The results of parallel double-core experiments indicate that after SMG flooding, the recovery of low permeability core increased by 29.5%, high permeability core increased by 15.3%, comprehensive recovery increased by 22.0%, and the ratio of low permeability recovery increased by nearly 2 times that of high permeability core. The soft microgel flooding technology can effectively activate the remaining oil in different pore sizes of the core, among which the medium pore (12.1%) is more used than the large pore (5.6%) and the small pore (4.2%).
EMG-based Monitoring Muscle Contraction Force to Determine Most Effective Exercise
Authors: Fu Jiawei , He Yichen , Jiang Siming , Tao Zhongqi , Wen Yifan , Yi Xingyu
Published: September 2021

—Electromyography (EMG) signals have been widely applied in fields of biomedical, clinical and human-machine interface [1]. And surface EMG (sEMG) technology could provide a non-invasive way to detect the stimulation degree of muscles and enable the control of artificial limbs. In this research, the main focus lies on one of the social problems—sedentariness. With the development of internet and electronic economy, computing time has undergone a steady increase around the globe, which extends the job time in long-term sitting [2]. Together with some non-ergonomic designs of chairs, many officers might experience an abnormal sitting posture and get injured in their muscles unconsciously. To scope the phenomenon in detail, a simulation is applied to reappear the condition of sedentariness of a common office worker. And a series of easily achieved movements were investigated to find out the corresponding effect in muscle exercise to compensate the negative influence caused by long-term sitting.
Comparison of calculating methods and applications of different concrete maturity
Authors: Geng Da-jiang , Dai Ning , Jin Xue-sheng , Miao En-xin
Published: September 2021

Concrete maturity theory has great potential in practical engineering. In this paper, the calculation and application of the concrete maturity are presented based on the qualitative analysis and quantitative calculations. Firstly, the maturity calculations are summarized by the methods of direct calculation and equivalent age calculation, as well as a theoretical discussion of the advantages and disadvantages of each calculation method. Secondly, the main methods of compressive strength and elastic modulus predicted by the concrete maturity are also summarized, and the calculation accuracy of the main calculation methods is compared with the published test results. Finally, based on actual engineering project, the research on concrete maturity is prospected to clarify the further research direction. The results show that the calculation methods of concrete maturity consist of direct calculation method and equivalent age calculation method, and the equivalent age calculation method is more reasonable in theory. Considering the wide range of construction temperature, the Freiesleben-Hansen equivalent age equation and exponential function prediction equation are recommended to predict the strength and elastic modulus of concrete.
Method for generating mesostructure of soil-rock mixture based on Minkowski sum
Authors: Zhang Peng , Chen Junqi , Xian Qingjun
Published: September 2021

The soil-rock mixture is widely distributed in nature, and the mechanical properties of it is a key concern in geotechnical engineering field. The mechanical response of soil-rock mixture can be obtained using numerical approaches. As the precondition for numeric simulation, the mesostructure of soil-rock mixture is indispensable. The random rock packing is the main step in the construction of the mesostructure. The classical trial packing method are inefficient when the rock area fraction is high. Permissible positions to pack new rock can be predicted in the algorithm using entrance block and background mesh, resulting in dramatic improvement in efficiency and robustness. Entrance block and Minkowski sum can be transformed into each other, and there are more algorithms for Minkowski sum. Therefore, a random rock packing algorithm based on Minkowski sum is constructed, each rock can be packed successfully at one time, avoiding multiple trials in the traditional trial packing method and improving the efficiency of packing.
Study on constraint degree calculation of frozen shaft inner wall mass concrete
Authors: Fang-zheng Li , Ji-wei Zhang , Wei-dong Wu , jin Yao , Xiao-gang Jin
Published: September 2021

Based on the circle-shaped air shaft of Hong Qing-He coal mine located in Inner Mongolia China, the thermal-mechanical numerical model of frozen shaft inner wall mass concrete was established under complex thermal-mechanical boundary, including internal heating, external cold source, friction constraints, above shaft load and lateral pressure. The evolution characteristics of temperature-displacement field of inner wall were analysed. According to numerical simulation results, the constraint degree at the middle section of inner wall concrete is calculated. In the early stage (0-10d), the constraint degree of inner wall fluctuates within 60-99% as curing time goes. Three protection measures to delete confinement degree of mass concrete shaft wall were proposed, including (1) Reducing the friction between inner and outer walls; (2) Reducing hydration heat release of mass concrete; (3) Reducing the temperature difference between inner and outer walls during curing.
Treatment technology for large deformation of tunnel passing through soft and fragmented zone
Authors: Xiaoteng Liang , Zhangru Shi
Published: September 2021

Large deformation is a major problem for tunnels, threatening engineering safety and increasing construction costs. In order to solve the large deformation problem of deep-buried tunnels passing through the soft and fragmented zone, relying on the Dafalang tunnel project under construction, the mechanism of the large deformation of the fracture zone tunnel is analyzed, and deformation control measures suitable for geological conditions are proposed accordingly. The large deformation of the Dafalang tunnel is the combined effect of many factors. The complex tectonic stress environment is the mechanical condition for the large deformation of the tunnel. The weak and broken surrounding rock is the material basis and internal condition of the large deformation of the tunnel. Optimizing construction parameters, grading deformation control, and combined length and short anchor rods are adopted to effectively reduce tunnel deformation and ensure construction safety and progress.
Preparation of CuO/Ag rough nanostructures as SERS-active substrates
Authors: Yang Qiong , Wang Jingjing , Wu Haoran , Li Chaorong
Published: September 2021

In this paper, CuO nanostructures with nanometer roughness were firstly prepared by electrochemical anodic oxidation method, and then CuO/Ag composite nanostructures were prepared by magnetron sputtering method on the surface of CuO substrate. The successful deposition of Ag films on CuO was confirmed by XRD, UV-Vis and SEM. In addition, the effects of different Ag sputtering time on substrate morphology and SERS properties were studied. Due to the many gaps between the rough CuO/Ag nanomorphology, the substrate has many “hot spots” and adsorption sites, which can effectively improve the SERS performance of the substrate. We selected R6G dye molecule as the probe molecule to evaluate the SERS performance of the substrate. The final experimental results show that the preparation method of CuO/Ag rough nanostructure is simple, and it has significant SERS performance improvement. The substrate’s detection limit for R6G can even reach 10-11M.
Compressive properties and microstructure evolution of sintered nano-silver
Authors: Gong He , Wu Hongcheng , Guo Hongcun , Yao Yao
Published: September 2021

In this work, the compressive properties of sintered nano-silver applied to the third generation semiconductor at room temperature are tested at a loading rate of 10-2s-1. The compressive stress-strain curve shows obvious elastic and plastic stage, and with the failure of the pore wall and sintering neck, the damage accumulates gradually until failure. The microstructure is analyzed statistically by scanning electron microscope. A finite element model for porous structure is developed by matching scanning electron microscope analysis. The elastic modulus of pore wall and sintering neck is obtained by combining the macro experimental data with the Ashby model. The local failure process of sintered nano-silver is simulated numerically. It is noted that the failure path is determined by large pore and pore spacing.
Mechanisms of Sinomenine Nanoparticles in the Treatment of Breast Cancer Based on Network Pharmacology
Authors: Chen Ting , Huang Xulong , Yang Chao , Huang Bin
Published: September 2021

This article mainly discusses the mechanism of SINOMENINE nanoparticles in the treatment of breast cancer by using the network pharmacology method. TCMSP and Swiss Target Prediction databases were searched for the target of SINOMENINE. The “breast cancer” target was searched through the GeneCards database. The common targets of both SINOMENINE and breast cancer were considered as the targets of SINOMENINE for treating breast cancer. The software Cytoscape 3.7.1 was used for topological analysis and visualization. The DAVID databases were used for GO enrichment analysis. A total of 57 key targets for the treatment of breast cancer were obtained, of which AKT1, MTOR, EGFR, NOS3, MAPK8, MMP9, etc. The results of pathway enrichment and functional annotation show that SINOMENINE mainly involves protein phosphorylation and positive regulation of nitric oxidebiosynthetic process by regulating Sphingolipid signaling pathway, Pathways in cancer, Measles, Smallcell lung cancer, Focal adhesion, and Insulin resistance. There are 10 major biological processes, including protein phosphorylation, signal transduction, negative regulation of apoptotic process, and protein autophosphorylation. This study not only initially revealed potential molecular mechanism of SINOMENINE, but also provided a reference for the in-depth development of SINOMENINE nanoparticles for the treatment of breast cancer.
Study on Permanent Thermal Insulation Formwork of Mass Concrete Prepared by Different Types of Nano-modified Lightweight Aggregate
Authors: Jiang Xiaojian , Zhang Sijia , Gu Zhifeng , Wang Licheng , Zhao Yunfei
Published: September 2021

Aiming at the problems of low strength, flammability, easy falling off, and aging of traditional organic thermal insulation materials, inorganic thermal insulation materials of different types of nano-modified lightweight aggregates were prepared in this paper. The feasibility of preparing permanent thermal insulation formwork of mass concrete with nano-modified lightweight aggregate was studied through experiments and calculation analysis of mechanical, durability, and thermal properties. The results show that the water absorption of shale ceramsite modified by nano-permeable hydrophobic agent is reduced to 1.21%, and the water absorption rate of inorganic precast hollow aggregate produced by nano-silica powder is lower, which is 0.79%. Inorganic precast hollow aggregate concrete, modified shale ceramsite concrete, and organic foamed aggregate concrete have the characteristics of high strength, fire resistance, aging resistance and low thermal conductivity. Inorganic precast hollow aggregate concrete and modified shale ceramsite concrete have excellent impermeability and frost resistance. Organic foamed aggregate concrete has the lowest thermal conductivity and good thermal insulation effect and its durability can be improved by surface protection technology. According to the principle of equivalent surface heat release coefficient, it is feasible to use lightweight aggregate precast formwork as permanent insulation formwork of mass concrete with thickness between 50 and 100 cm. The permanent thermal insulation formwork of nano-modified lightweight aggregate concrete can also be used as the formwork for concrete construction to realize the temperature control measures of tracking thermal insulation and slow cooling of mass concrete, reduce the risk of cracking, and improve the construction efficiency.
Study on ionic liquid treatment and enzymatic hydrolysis of corn stover after activation of zinc chloride solution
Authors: Zeng Guoming , Huang Xin , Li Yan , Sun Da , Zhou Bin
Published: September 2021

With the intensification of the energy crisis, this thesis uses corn stalk cellulose as the raw material to carry out research on biomass energy. By designing the response surface experiment, a multiple quadratic regression equation prediction model of the response surface factors and the yield of enzymatic reducing sugars after the activation of the zinc chloride solution treated by the ionic liquid was established, which provided the technology for the ionic liquid treatment of the metal ion solution to activate the corn stalk raw materia reference. The experimental results show that the yield of enzymatically hydrolyzed reducing sugars of corn stalks after being activated by metal ions and then treated with ionic liquids is greatly improved compared to the raw materials.
Study on Micro-arc Oxidation of Mg-Zn-Y-Nd-Ca Magnesium Alloys
Authors: Dai Yuelai , Li Yulei , Lv Juan , Li Jingwei
Published: September 2021

To solve the problem of rapid degradation of magnesium alloy implanted in human body, the surface of magnesium alloy was modified by micro-arc oxidation treatment. In order to improve the comprehensive mechanical properties and corrosion resistance of magnesium alloy materials, a new type of Mg-Zn-Y-Nd-Ca degradable magnesium alloy materials was formed by adding a certain proportion of rare earth elements Y and Nd, as well as Zn and Ca. A micro - arc oxidation layer containing Ca, P and Si was formed on the surface of magnesium alloy by secondary micro - arc oxidation. The surface of the micro-arc oxidation film was covered by sol-gel technology to reduce the micro-crack and micro-pore structure of the film and improve the corrosion resistance of the film in the human body simulation liquid.
Metal-Organic-Frameworks-driven hollow core-shell C03O4/TiO2 Heterojunction for Enhancement of Photocatalytic Hydrogen generation
Authors: Xiao Guangsheng , Pan Jiaqi , Fu Yueyue , Li Chaorong
Published: September 2021

In recent years, how to further enhance the efficiency of photocatalytic hydrogen generation has become a research hotspot. At present, the metal-organic-frameworks (MOF) has attracted much attention in the field of catalysis due to its special physical and chemical properties. Herein, the hollow core-shell Co3O4/TiO2 heterojunction is prepared by deposition and annealing method with ZIF-67 as self-sacrificial templates and metal precurous. The characterzation of XRD, SEM, and TEM indicate that the hollow core-shell Co3O4/TiO2 heterojunction is synthesized successfully. The characterzation of UV, PL indicate that the Co3O4/TiO2 show superior photoelectric performance. By evaluation, the Co3O4/TiO2 heterogeneous catalyst exhibits a remarkable photocatalytic hydrogen production performance, which is ∼11 and ∼14 times higher than that of pure Co3O4 and TiO2. Studies prove that the formation of heterojunction can promote charge carriers separation, the hollow structure can raise the solar efficiency, offer more surface areas and active sites, all these are beneficial for photocatalytic performance.
A transparent photovoltaic device of NiO/CdS arrays pn junction
Authors: Fu Wendi , Pan Jiaqi , Li Chaorong
Published: September 2021

The transparent NiO/CdS P-N junction device composite structure was prepared by hydrothermal method and radio frequency magnetron sputtering. The results show that the NiO is orderly arranged on the CdS arrays. In addition, the photoelectric properties of the transparent NiO/CdS device grown at different hydrothermal temperatures are also different. As revealed, the device prepared at 180°Cexhibits a better photoelectric performance.
Antisolvent engineering for mixed tin-lead inorganic perovskite solar cells
Authors: Chen Hao , Zhang Ting , Li Shibin
Published: September 2021

Recently, inorganic perovskite has been a research hotspot due to its thermal stability and promising photovoltaic performance. Here, we demonstrate the antisolvent engineering can assist the fabrication of the mixed tin-lead inorganic perovskite films. The treated devices exhibit enhanced stability in atmosphere air. The champion perovskite solar cells (PSCs) treated with anisole exhibits a power conversion efficiency of 9.3% with an open-circuit voltage over 0.8 V.
Improved Resistive Switching of Ru: SiO2/TiO2 Based Memristive Devices
Authors: Gu P. , Nasir I. , Yang Z. Q. , Chen K. X. , Li D. Y. , Jiang X. D. , Li W.
Published: September 2021

In this paper, the resistive switching behaviors of Ru:SiO2/TiO2 based memristive devices have been investigated. It is found that the random and uncontrolled formation of conductive filaments in the Ru/Ru:SiO2/p++-Si devices are crucial to realize a filamentary resistive switching. It is also found that the resistive switching behavior of Ru/Ru:SiO2/p++-Si devices could be significantly improved via inserting a TiO2 interfacial layer as in the form of Ru/Ru:SiO2/TiO2/p++-Si device structure. In the modified device, strong and stable conductive filament formation could be realized when the top electrode is positively biased. In addition to nonvolatile memory applications, an analog-type switching behavior has also been realized in our newly proposed resistive switching device. The current obtained analog conductance modulation is essential for simulating synaptic functions in electronic devices for neuromorphic applications.
Preparation of strong green fluorescence carbon quantum dots for cancer cell imaging
Authors: Tao Junting , Zou Hao , Lu Xinjian , Liao Xiaokun , Pan Jiaqi , Li Chaorong , Zheng Yingying
Published: September 2021

Carbon quantum dots (CQDs) were prepared throught hydrothermal synthesis method. The TEM and FT-IR spectra showed the successful synthesis of CQDs and the well water solubility of CQDs. After CQDs were co-cultured with human breast cancer cells (MCF-7 cells), the cells were stained and emitted stronge green fluorescence, indicated that CQDs had a good application prospect in cancer cell imaging.
Application of New Mxene Based Materials in Electrochemical Sensors
Authors: Zhang Xiang , Gu Yu
Published: September 2021

In the current research on the application of new Mxene based materials in electrochemical sensors, the research on the charge storage of new Mxene based materials is not comprehensive enough. The charge storage of new Mxene based materials under different scanning rates is studied in the form of experiments. According to the needs of the experiment, experimental reagents and instruments were selected to prepare Mxene solution and new Mxene based materials. Macroporous Mxene was prepared as the electrode of EES device to store and convert energy. The enzyme was immobilized on the inner surface of Ti3C2Tx to sense biological activity. The experimental results show that the charge storage performance of the new Mxene based materials is the best when the scanning rate is 15mVs-1, which is the most suitable for electrochemical sensors.
Crystallization and phase separation of tungsten oxide-bismuth vanadate amorphous film by annealing in air
Authors: Li Chao , Song Haili , Zhang Yuanyuan , Miao Lei , Qi Ruijuan , Huang Rong , Cui Chengqiang
Published: September 2021

A WO3-B1VO4 amorphous film grown on the (001) yttria-stabilized zirconia (YSZ) substrate was annealed at 600 °C in air. The microstructures evolution was investigated by X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy. After annealed, the amorphous composite film crystalized into monoclinic BiVO4 and orthorhombic WO3. B1VO4 epitaxially grew on the YSZ, forming the matrix, where part of small irregular WO3 grains were embedded in. Other large-sized sub-stoichiometric WO3-6 (0<δ<3) grains with stacking faults lay on the film surface, which may contribute to the compressed strain of BiVO4 matrix vertically. Compared to the typical vertical heteroepitaxial nanocomposite of WO3-B1VO4 film grown at 600 °C by pulsed laser deposition, in the annealed composite film, the vertical lattice mismatched strain at WO3/B1VO4 interface decreased and lead to the disappearance of metastable hexagonal WO3.
Numerical investigation of flow and noise characteristics of the sea suction value
Authors: Zeng Rongtao , Sun Mingkang , Liu Jian , Bai Zongliang , Song Daoyuan , Wen Sha
Published: September 2021

The ship industry has been developed considerably in the engineering applications of deep-sea energy extraction, and the hydrodynamic performance and noise level of ships have become the focus of research for scholars and industries. In order to study the flow characteristics and acoustic characteristics of the sea suction valve, this paper conducts numerical simulation of the internal flow field and acoustic characteristics of the sea suction valve and the noise elimination trunk structure based on the numerical method of computational fluid dynamics. Through the study and analysis of different sea suction valve structures and different depths of noise elimination trunk on the flow characteristics and acoustic characteristics, it is helpful to provide guidance for engineering optimization design.
Study on the Dynamic Behavior and Impact of Tire Fragments on Aviation Aluminum Alloy Plates
Authors: Zhang Ke , Chen Qing , Wu Xiaoyang , Wang Peiyan , Yue Zhufeng
Published: September 2021

This paper presented the dynamic behavior of tire fragments and their impact on aluminum alloy plates by the methods of experiment and numerical simulation. In the experiment, the impacts of tire fragments on aluminum alloy plates under quadrilateral constraint, bilateral constraint and four-corner constraint were studied. According to the experimental results and based on Ogden model and Johnson-Cook model, a simulation calculation model for fragment impact was proposed. Analysis of plastic deformation area, failure mode, etc. verified that the proposed model could stimulate the impact of tire fragments on aluminum alloy plates. By comparing different constraint conditions, it is found that within the impact range, the plate under quadrilateral constraint can resist the strongest impact.
A Survey of Application and Development of Small Disturbance Equation Method in the Aviation Area
Authors: Shan Shuang , Chen Weiyu , Chen Zelong
Published: September 2021

All the small disturbance equation (SDE) methods, which are a useful technique to enhance the stability and security of the aircraft, play a significant role in the development of the aviation area. This review paper briefly introduces the development of the SDE and summarizes the two calculation methods combining with the SDE and application of the SDE method in the aviation area. The calculation methods mainly focus on the approximate factorization (AF) algorithm with the SDE and Newton-Orthomin method with the SDE. AF algorithm with the SDE is robust enough, and it can choose the calculation methods according to accuracy rather than stability that significantly saves the calculation cost. The newton-Orthomin method with the SDE can improve computing efficiency by 2.1 to 4.5 times compared with the monotone AF method. The direction of application focus on the flutter analysis, gust analysis and resizing of some component in the aircraft and the disadvantages are explored for each type. In conclusion, the combination of the SDE with the other algorithms can increase calculation efficiency, and the SDE has a wide range of applications in the aviation area. This paper can provide relevant references for the subsequent combination of the SDE and other algorithms development or practical application of SDE.
APPLICATION OF MESO-MODEL OF CONCRETE LOW-VELOCITY IMPACT IN PAVEMENT
Authors: Zhang Xiaoliang , Wang Junpei , Feng Xuekai , Ning Huijun
Published: September 2021

Concrete pavement is one of the typical highway structures at home and abroad. Most of the existing research on the performance of concrete pavement is based on the macroscopic angle of view. The complex meso-structure inside is ignored. Due to the incomplete research on concrete pavement structure, it is difficult to reveal the physical mechanism of concrete pavement deformation and damage. In order to understand the failure mechanism of concrete pavement more clearly, this paper started from the microscopic perspective. Firstly, based on the experimental phenomena, a multi-grade aggregate model was randomly placed in the concrete slab, and the interface between the aggregate and mortar was generated at the same time to establish a three-dimensional three-phase mesoscopic bone and the finite element calculation model of the material. Secondly, the damage effect of concrete specimens in homogeneous modeling, meso-modeling and experimental phenomena were compared to verify the accuracy of the selected concrete material parameters and the feasibility of meso-modeling method. Finally, the concrete failure form under three different aggregate contents and the influence of internal aggregate content of the concrete pavement on the mechanical properties of the concrete pavement were analyzed. The calculation results showed that compared with the macroscopic simulation, the mesoscopic model was more consistent with the experimental phenomena of the failure effect of the concrete specimens. And the numerical simulation results with the aggregate content of 46.6% were the most consistent with the experimental results. Comparing the failure modes of concrete specimens with different aggregate contents, it was found that the concrete specimens with an aggregate content of 60.6% have a lighter degree of damage. When the aggregate content was 30.6%, the impact tooth penetrated half of thickness of the concrete specimen, and the aggregate content is 60.6% of the impact teeth penetrated one third of the concrete specimen. Therefore, the higher the aggregate content is, the stronger the ability of the concrete specimens has to resist damage.
A Quasi-Static Model of Explosive Spherical Charge in Rock and Soil with Impulsive Impedance
Authors: Pengyi Li , Yunzhe Liu , Shiying Tang , Qiang Lu , Kaikai Li , Ao Li
Published: September 2021

The incident wave pressure acting on the wall of the spherical charge in the rock and soil is an important factor affecting the size of the explosion cavity, and the pressure of the incident wave is related to the impedance of both the explosive and the rock and soil. In this paper, based on the quasi-static model of explosive spherical charge in rock and soil, the impact impedance was introduced to calculate the size of explosion cavity in rock and soil medium. Through the field underground explosion experiment, it is found that the calculation result of the impact impedance model is 6.15% higher than the original model, and the influence rule of several geotechnical medium parameters on the cavity size was also analyzed.
Research on Aircraft Ditching State Selection Based on Floating Characteristics of Water Surface
Authors: Jiang Ting , Zuo Zi-bin , Sun Feng , Hu Qi , Luo Peng
Published: September 2021

When an airplane is forced to ditching on water, slight state changes, such as weight, center of gravity, initial attitude, etc., will have great influence on the ditching performance and floating ability of the airplane. In order to study the floating ability of the aircraft under the above parameters, this paper takes a fixed-wing aircraft as the basis model, and based on hydrostatics, divides the water inflow into several tiny water inflow segments. By studying the floating attitude and floating time of different aircraft states, the influence law of the center of gravity position parameters on the floating time is mastered. The research shows that the floating time and water inflow volume of the aircraft will be significantly increased when the higher center of gravity position and the non-most unfavorable longitudinal range of the center of gravity are adopted, and forced landing on water in this state can provide emergency evacuation and escape for the aircraft personnel.
Optical simulation analysis and study of UTEM electron gun
Authors: Chen He , Dong Quanlin , Wang Haiyang , Yang Ziyu
Published: September 2021

In this paper, the electric field intensity of the electrode structure of the thermally emitted electron gun of UTEM is simulated, and the relation between the electric field intensity distribution and the electrode plate is analyzed. Using the electronic optics software, the optical system of the electron gun is simulated, the performance parameters of the electron gun are obtained, and the advantages and disadvantages of the whole optical system are analyzed. The research results of this paper can provide a reference for the design and simulation of similar electron gun.
Numerical investigation on water-entry impact load of TMA based on CEL algorithm
Authors: Hao Dong , Yu Jing
Published: September 2021

This work presents comprehensive numerical research on the impact load of the trans-medium aircraft (TMA) using the coupled Eulerian-Lagrangian (CEL) method during a water-entry event. The water-entry velocity, angle, and attitude play a significant role in the impact load characteristics of the water-entry trajectory. In this paper, a numerical model of a typical TMA structure is established to study the water-entry load with the velocity 0, 2m/s, 4m/s, 6m/s, 8m/s, the angle 90°, 80°, 70°, 60°, 50°, the attitude 90°, 80°, 70°, 60°, 50°. Subsequently, the variation laws of the impact load with different water-entry velocity, angle, and attitude are analyzed. The results obtained from this investigation can supply a good reference to structural design of the TMA.
Analysis of Euler Characteristic
Authors: Liu Yilin
Published: September 2021

Usually, people first learn about Euler characteristic in three-dimensional space, related to the famous Euler formula. This invariant is explained in a top-down manner. In particular, there is an invariant first defined on general smooth manifold. Then, looking at different properties of this invariant leads to the discover of coincidence with Euler formula in lower dimension case. This paper extends the definition of Euler characteristic to more general geometries by glueing, and seeks for some possible applications. Result shows that Euler Charisteristic is an useful invariant that ties many subject in topology together. By studying Euler Characteristic in various cases, one may found interesting relationship between objects that are not seemingly related.
Predict the Plastic Deformation of Perforated Sheet Metals using Image-based Finite Element Modeling
Authors: Wang Lin
Published: September 2021

In this work, numerical prediction of the plastic deformation behaviors of perforated sheet metals, specifically AISI 1018 low carbon steel, C260 Cu-Zn brass, under uniaxial tension was carried out. An image-based mesh generation technique was applied to better represent and discretize the perforated geometry of sheet metal specimens. Digital image correlation measured displacement boundary conditions were also implemented into the finite element modeling. The predicted results of perforated sheet metal under tension as nominal stress-strain curves and localized plastic strain distribution agree well with the experimental observations. Possible error sources and uncertainty of this image-based finite element modeling were also discussed.
A comparison of the extended Kompaneets equations with the Ross-McCray equation
Authors: Miao Yuchan , Gao Haixiang , Liu Dangbo
Published: September 2021

The Kompaneets and the Ross-McCray equations can be used to describe the Comptonization process. However, the classical Kompaneets equation fails to describe down-Comptonization while Ross-McCray equation can be applied to describe down-Comptonization but inappropriate for a blackbody equilibrium. Fortunately, the Kompaneets equation extended by frequency and the Kompaneets equation extended by momentum can solve both problems. The different physical connotations behind the four equations bring about formal differences that allow the spectral evolution under different conditions to show different characteristics. In order to compare the differences between the four equations, the evolution of our common radiation spectra in astrophysics is numerically calculated in this paper. Besides, the differences between the four diffusion equations are discussed from their physical significance to the evolutionary phenomena. According to the results, the four equations evolve at different rates during down-Comptonization, from fast to slow in order of the Kompaneets equation extended by frequency, the Kompaneets equation extended by momentum, the classical Kompaneets equation and the Ross-McCray equation. The regression of the four equations is consistent during up-Comptonization. The Ross-McCray equation eventually converges to a different end state at near equilibrium. These results shed light on analytical development of Comptonization process.
Yield Estimation Model and Its Accuracy Analysis for Near-Surface Explosions of Soil-Rock-Mixture Site
Authors: Zhang Liangyong , Tang Shiying , Lu Qiang , Li Xin , Fang Houlin , Li Yaolong , Zhang Dezhi
Published: September 2021

Explosion yield estimation based on seismic data (ground motion in the near field) is one common approach to estimate near-surface explosion yield. The near-surface yield estimation models of different site media are usually established through chemical explosion experiments. However, the site media of current chemical explosion experiments are mainly soil and hard rock, lacking the experiment data and yield estimation model of soil-rock-mixture site. To solve the above problem, the seismic (ground motion) data of chemical explosion experiments at different depths in soil-rock-mixture site were gathered to establish the near-surface yield estimation model for soil-rock-mixture site. Besides, analysis was made regarding yield estimation accuracy and effects of rock-soil types on accuracy. The results show that the rock-soil type has great influence on the yield estimation accuracy of near-surface explosions, and the near-surface yield estimation model of soil-rock-mixture site has high accuracy in estimating explosion yield.
Research on the optimal strategy of desert crossing game under known weather conditions
Authors: Song Xiaonan , Feng Xiaojie , Mao Yuanyuan
Published: September 2021

The “Crossing the Desert” mini-game needs to consider a variety of mutually restrictive factors. Players must coordinate funding and path issues to find the optimal strategy to reach the end within the specified time. Based on the study of crossing the desert when the weather conditions are known, this paper establishes a topology model, and uses priority search and game theory to solve the player’s optimal strategy for passing through the barriers. First, the entire map is digitized and represented by a general topological map; then, given the map and weather distribution, the highest profit of each path is calculated. Specific calculation details require further analysis to arrive at a more practical and efficient route planning plan. The model proposed in this paper only provides a more effective solution for this problem from the perspective of mathematical modeling.
Several basic properties of complex numbers
Authors: Gan Yuxuan , Zhou Yingtong , Zou Qiahao
Published: September 2021

Complex numbers play a fundamental role in multiple engineering fields. In this paper, we first review what the algebraic form of a complex number is and define several operations on complex numbers. At last, we introduce Blaschke factors and discuss inequalities of complex numbers.
A note on vanishment of Fourier coefficients
Authors: Mo Junyi
Published: September 2021

A Fourier series is one of the methods to represent a function as a summation of orthogonal functions. In this paper, we give a detailed proof of a property regarding the behavior of a function at its continuity points. Finally, we show that an integrable function vanishes at its continuity points if all of its Fourier coefficients vanish.
Numerical study on subsonic-supersonic Laval nozzle
Authors: Ji Xingyue , Zhi Junshen , Pan Hongyu
Published: September 2021

Because subsonic-supersonic Laval nozzles are widely used in many fields, the flow characteristics of the subsonic-supersonic Laval nozzle are studied by numerical simulation. First, the MacCormack scheme is used to discrete the non-conservation and conservation forms of the governing equations of the flow in the subsonic-supersonic Laval nozzle. The flow states inside the nozzle in both formats are then compared. The results show that the numerical results of the two schemes converge well. The variation of the fluid velocity and outlet pressure is more pronounced in the non-conservative form. For the conservation form, the error of the mass flow rates at different positions is constant and acceptable, which is about 1%. For the non-conservation form, the error at different locations within the nozzle is different, reaching a minimum error at the throat. In addition, studies on grid length have demonstrated that the finer the grid, the more accurate and stable the results Moreover, for the subsonic, supersonic isentropic flow in the quasi-one-dimensional nozzle, the Mach number and velocity become larger along with the nozzle. In contrast, other variables such as pressure and temperature become smaller. There is a subsonic region in front of the throat and a supersonic region behind the throat. The Mach number of the nozzle exit can be very high. Finally, the study reveals the internal flow state of the subsonic, supersonic nozzle, which can provide theoretical reference for the application of the nozzle.
Dynamic Characteristics Analysis and Chaotic Synchronization of Fractional Order Financial Dynamic System
Authors: Liu Xiaoshan , Dong Jun , Han Liang , Ma Hu
Published: September 2021

The equations of time-delay fractional order financial dynamic system are studied. Fractional calculus, as the expansion of the corresponding integer parts, has more complex definition and update laws. It is found that modeling by fractional-order differential equation in some nature phenomenon and engineering field can be consistent with essentiality of the phenomenon and matters, such as in mathematical modeling of viscoelastic materials, electromagnetic wave and other fields. Moreover, there exist more complex dynamical behaviors in fractional-order dynamical system than in integral-order one, and it has more preferable history memory ability. Therefore, it is of theoretical value and practical significance researching the fractional-order nonlinear dynamical systems on the base of the researches on the traditional integral-order nonlinear dynamical system.
High-Mass X-ray binary: Classification, Formation, and Evolution
Authors: Tan Chengzhuo
Published: September 2021

A high mass X-ray binary is a binary system consisting of an accreting neutron star or black hole and an early-type star with more than 10 solar masses. A compact star produces X-ray radiation during the accretion of material from the stellar wind or Roche lobe. High-mass X-ray binaries are ideal places to study dense stars, stellar winds, material exchange between binary stars, and the evolution of massive binary stars. In this review, the observational properties, classification, and evolution of high mass X binaries are described. According to the mass and types of X-ray resources, this review classifies the X-ray binaries and list out their features.
Measurement method of black hole spin and its application in jet
Authors: Liu Silong
Published: September 2021

Spin is an important property of black holes. The formation of jet and black hole is related to spin. At present, there are two commonly used spin measurement methods, the X-ray reflection method, and the continuum-fitting method. By analyzing the distribution of black hole spin in black hole binary system measured by these two methods, we find that in high-mass X-ray binaries, black holes have high spin, this is because the companion stars have a large mass and short lifetime, the black holes don’t have enough time to accelerate the spin by accretion so must be bored with high spin. However, in low-mass X-ray binaries, the spin will be widely distributed because they have enough time to increase spin by accreting gas. And according to the existing data, we can also get the relationship between spin and jet. However, both methods are affected by the complex physics of the accretion disk, in the future, gravitational waves will become another effective tool to measure the spin of black holes.
On Surfaces Properties of Doubly Warped product Manifolds
hI×fB in generalized Robertson-Walker spacetimes
Authors: Du LingWei , Wang Jian
Published: September 2021

This paper concerns the properties of submanifolds of doubly warped product space. For Riemannian manifold B and interval I, we investigate some surfaces properties of doubly warped product manifolds
hI×fB, and obtain the scalar curvature for the doubly warped product space.