143 results on '"Xinbo He"'
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2. Analysis of coupling characteristics of whip antenna on aircraft carrier under incident electromagnetic pulse of high-altitude nuclear electromagnetic pulse
- Author
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Meng CHEN, Bing WEI, and Xinbo HE
- Subjects
finite different time domain ,high-altitude nuclear electromagnetic pulse ,half space plus source ,thin wire algorithm ,antenna ,aircraft carrier ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 - Abstract
ObjectivesUnder the condition of considering the influence of the sea surface, the relationships between the induced current of a whip antenna on a large ship under the incidence of high-altitude nuclear electromagnetic pulse (HEMP) and the incident angle of the pulse and antenna position are studied.Methods The half-space finite different time domain (FDTD) method is used to consider the influence of the sea surface; the thin wire algorithm is used to solve the problems of huge computational grid and low efficiency caused by the fine structure; the lumped element FDTD method is used to consider the influence of the load behind the antenna on the induced current; and a parallel algorithm based on MPI is used to speed up the calculation.ResultsThe results show that the induced current on the whip antenna of an aircraft carrier model is related to the antenna position and incident angle in the HEMP incident case. The peak value of the induced current at the antenna port is 5.6 A in typical cases.ConclusionsThe analysis shows that the magnitude of the induced current at the antenna port mainly depends on the antenna position and has little relationship with the incident angle of the pulse. The research provides an algorithm basis for the calculation and analysis of induced current in the case of the incident pulse electromagnetic wave of large ships, and the research results provide a theoretical support for the analysis of ship electromagnetic compatibility problems.
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- 2023
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3. Microstructure and performance of carbon fiber reinforced aluminum matrix composites with molybdenum carbide coating on carbon fibers
- Author
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Tingting Liu, Xinbo He, Lin Zhang, Shubin Ren, and Xuanhui Qu
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carbon fibers ,aluminum matrix composites ,molybdenum carbide coating ,interfaces ,Materials of engineering and construction. Mechanics of materials ,TA401-492 ,Chemical technology ,TP1-1185 - Abstract
In this work, a molybdenum carbide coating on the surface of short carbon fibers prepared using molten salt method was proposed to ameliorate the interfacial bonding and improve the performance of carbon fiber/Al composites. The carbon fiber/Al composites were produced using vacuum hot pressing. The characteristics of molybdenum carbide coating were analyzed. Besides, the microstructures, bending strength and thermal properties of the carbon fiber/Al composites were explored. Furthermore, the interfacial thermal resistance of the composites was investigated in relation to theoretical evaluations derived from the combined Maxwell-Garnett effective medium approach and acoustic mismatch model schemes. The results indicated that a homogeneous Mo _2 C coating with a thickness of 0.5 μ m was obtained by proper molar ratio of carbon fibers, MoO _3 and chloride salts mixture and heated at 1000 °C for 60 min. The Mo _2 C coating greatly enhanced the bond between the aluminum matrix and carbon fiber, leading to improvements in the densification behavior and bending strength of the coated composites. The enhanced thermal properties including improved thermal conductivity and reduced coefficient of thermal expansion (CTE) were also achieved by the Mo _2 C coating. The in-plane thermal conductivity of 60 vol.% Mo _2 C-coated carbon fiber/Al composite was 221 W·m ^−1 ·K ^−1 enhanced by 92% compared to that of uncoated composite and the CTE was 6.0 × 10 ^–6 K ^−1 which was suitable for electronic packaging materials.
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- 2024
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4. Investigation on the Attainment of High-Density 316L Stainless Steel with Selective Laser Sintering
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Pengfei Zhu, Xinbo He, Hongda Guan, Zijian Zhang, Tao Zhang, and Xuanhui Qu
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selective laser sintering ,additive manufacturing ,316L stainless steel ,sintering atmosphere ,mechanical property ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Due to the low density of the green part produced by selective laser sintering (SLS), previous reports mainly improve the sample’s density through the infiltration of low-melting metals or using isostatic pressing technology. In this study, the feasibility of preparing high-density 316L stainless steel using 316L and epoxy resin E-12 as raw materials for SLS combined with debinding and sintering was investigated. The results indicated that in an argon atmosphere, high carbon and oxygen contents, along with the uneven distribution of oxygen, led to the formation of impurity phases such as metal oxides, including Cr2O3 and FeO, preventing the effective densification of the sintered samples. Hydrogen-sintered samples can achieve a high relative density exceeding 98% without losing their original design shape. This can be attributed to hydrogen’s strong reducibility (effectively reducing the carbon and oxygen contents in the samples, improving their distribution uniformity, and eliminating impurity phases) and hydrogen’s higher thermal conductivity (about 10 times that of argon, reducing temperature gradients in the sintered samples and promoting better sintering). The microstructure of the hydrogen-sintered samples consisted of equiaxed austenite and ferrite phases. The samples exhibited the highest values of tensile strength, yield strength, and elongation at 1440 °C, reaching 513.5 MPa, 187.4 MPa, and 76.1%, respectively.
- Published
- 2023
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5. A novel fractional grey forecasting model with variable weighted buffer operator and its application in forecasting China's crude oil consumption
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Yong Wang, Yuyang Zhang, Rui Nie, Pei Chi, Xinbo He, and Lei Zhang
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Grey forecasting model ,Variable weighted buffer operator ,Particle swarm optimization ,Oil consumption forecast ,Petroleum refining. Petroleum products ,TP690-692.5 ,Engineering geology. Rock mechanics. Soil mechanics. Underground construction ,TA703-712 - Abstract
Oil is an important strategic material and civil energy. Accurate prediction of oil consumption can provide basis for relevant departments to reasonably arrange crude oil production, oil import and export, and optimize the allocation of social resources. Therefore, a new grey model FENBGM(1,1) is proposed to predict oil consumption in China. Firstly, the grey effect of the traditional GM(1,1) model was transformed into a quadratic equation. Four different parameters were introduced to improve the accuracy of the model, and the new initial conditions were designed by optimizing the initial values by weighted buffer operator. Combined with the reprocessing of the original data, the scheme eliminates the random disturbance effect, improves the stability of the system sequence, and can effectively extract the potential pattern of future development. Secondly, the cumulative order of the new model was optimized by fractional cumulative generation operation. At the same time, the smoothness rate quasi-smoothness condition was introduced to verify the stability of the model, and the particle swarm optimization algorithm (PSO) was used to search the optimal parameters of the model to enhance the adaptability of the model. Based on the above improvements, the new combination prediction model overcomes the limitation of the traditional grey model and obtains more accurate and robust prediction results. Then, taking the petroleum consumption of China's manufacturing industry and transportation, storage and postal industry as an example, this paper verifies the validity of FENBGM(1,1) model, analyzes and forecasts China's crude oil consumption with several commonly used forecasting models, and uses FENBGM(1,1) model to forecast China's oil consumption in the next four years. The results show that FENBGM(1,1) model performs best in all cases. Finally, based on the prediction results of FENBGM(1,1) model, some reasonable suggestions are put forward for China's oil consumption planning.
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- 2022
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6. FDTD Complex Terrain Modeling Method Based on Papery Contour Map
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Meng Chen, Bing Wei, and Xinbo He
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Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Cellular telephone services industry. Wireless telephone industry ,HE9713-9715 - Abstract
This study aims to develop a finite difference time-domain (FDTD) modeling method for complex terrain using a paper contour map. First, the image preprocessing technology is employed to segment, denoise, and number the drawing area to arrive at independent figures and curve matrices. Subsequently, the support vector machine (SVM) classifier is implemented to identify the number and obtain the elevation value pertinent to the curve in the figure. Finally, the scattered points in the curve matrix are meshed by the Delaunay triangulation algorithm, and a three-dimensional triangular mesh model is established according to the recognition results. The FDTD calculation model is established by the method of intersection of Yee cell grid lines and triangle projection. The simulation results reveal that the recognition rate of the SVM classification model in this study is close to 100% for printed numerals. This approach is capable of quickly and accurately establishing the FDTD-based calculation model for complex terrain on the basis of the paper contour map.
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- 2023
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7. Hybrid FDTD algorithm for electromagnetic analysis of fine structures
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Sihan Zhao, Bing Wei, Xinbo He, Yiwen Li, and Xiaolong Wei
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Finite-Difference Time-Domain (FDTD) ,Unconditionally stable ,Explicit ,Hybrid FDTD ,Unstable modes ,Physics ,QC1-999 - Abstract
A new hybrid Finite-Difference Time-Domain (hybrid FDTD) algorithm is proposed in this paper. This hybrid FDTD method combines the superiorities of explicit unconditionally stable FDTD (US-FDTD) and traditional FDTD methods to achieve unconditional stability and high calculation efficiency. US-FDTD is used in fine grids and the adjacent coarse grids subdomain and it breaks the Courant-Friedrich-Levy (CFL) condition. Traditional FDTD is used in the remaining coarse grids subdomain and it is a matrix free method. A compensation scheme is used on the subdomain boundary without compromising accuracy. Hybrid FDTD makes the explicit time marching with a uniform time step determined by the size of coarse grid in whole domain, which reduces the iteration time. In addition, because US-FDTD is only used in one of the subdomains, compared with global US-FDTD method, the matrix dimension of hybrid FDTD is reduced, which saves the time for eigenvalue solution. Numerical results show high efficiency and accuracy of the proposed method.
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- 2021
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8. The Optimization of Ti Gradient Porous Structure Involves the Finite Element Simulation Analysis
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Bowen Liu, Wei Xu, Xin Lu, Maryam Tamaddon, Mingying Chen, Jiaqi Dong, Yitong Liu, Lijia Guo, Jiazhen Zhang, Xuanhui Qu, Xinbo He, and Chaozong Liu
- Subjects
titanium ,gradient porosity ,oral implants ,three-dimensional finite element simulation ,bone stress ,Technology - Abstract
Titanium (Ti) and its alloys are attracting special attention in the field of dentistry and orthopedic bioengineering because of their mechanical adaptability and biological compatibility with the natural bone. The dental implant is subjected to masticatory forces in the oral environment and transfers these forces to the surrounding bone tissue. Therefore, by simulating the mechanical behavior of implants and surrounding bone tissue we can assess the effects of implants on bone growth quite accurately. In this study, dental implants with different gradient pore structures that consisted of simple cubic (structure a), body centered cubic (structure b) and side centered cubic (structure c) were designed, respectively. The strength of the designed gradient porous implant in the oral environment was simulated by three-dimensional finite element simulation technique to assess the mechanical adaptation by the stress-strain distribution within the surrounding bone tissue and by examining the fretting of the implant-bone interface. The results show that the maximum equivalent stress and strain in the surrounding bone tissue increase with the increase of porosity. The stress distribution of the gradient implant with a smaller difference between outer and inner pore structure is more uniform. So, a-b type porous implant exhibited less stress concentration. For a-b structure, when the porosity is between 40 and 47%, the stress and strain of bone tissue are in the range of normal growth. When subject to lingual and buccal stresses, an implant with higher porosity can achieve more uniform stress distribution in the surrounding cancellous bone than that of low porosity implant. Based on the simulated results, to achieve an improved mechanical fixation of the implant, the optimum gradient porous structure parameters should be: average porosity 46% with an inner porosity of 13% (b structure) and outer porosity of 59% (a structure), and outer pore sized 500 μm. With this optimized structure, the bone can achieve optimal ingrowth into the gradient porous structure, thus provide stable mechanical fixation of the implant. The maximum equivalent stress achieved 99 MPa, which is far below the simulation yield strength of 299 MPa.
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- 2021
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9. Mesporous 3C-SiC Hollow Fibers
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Yangwen Liu, Huilin Hou, Xinbo He, and Weiyou Yang
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Medicine ,Science - Abstract
Abstract In the present work, for the first time, we reported the exploration of mesoporous 3C-SiC hollow fibers via single-spinneret electrospinning of polyureasilazane (PSN) and polyvinylpyrrolidone (PVP) solution followed by high-temperature pyrolysis treatment. The resultant products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and N2 adsorption. The as-prepared hollow fibers with totally mesoporous walls were uniformly sized in diameter and high purity in morphology. They were composed of single-crystalline 3C-SiC nanoparticles with a surface area of 21.75 m2/g and average pore diameter of ~34 nm. The PSN concentration played a determined role on the formation of hollow fibers rather than the conventional solid counterparts, enabling their growth in a tunable manner. A possible mechanism was proposed for the formation of mesoporous SiC hollow fiber.
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- 2017
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10. Preparation of W-Plated Diamond and Improvement of Thermal Conductivity of Diamond-WC-Cu Composite
- Author
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Xulei Wang, Xinbo He, Zhiyang Xu, and Xuanhui Qu
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diamond-WC-Cu composite ,cyclic vacuum pressure infiltration ,thermal conductivity ,interface thermal resistance ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The tungsten (W)-plated diamond process was explored and optimized. A dense and uniform tungsten coating with a thickness of 900 nm was successfully prepared by the powder covering sintering method. The Diamond-WC-Cu composite with high density and high thermal conductivity were successfully prepared by cyclic vacuum pressure infiltration. The microstructure and composition of the W-plated diamond particles were analyzed. The effect of tungsten coating on the microstructure and thermal conductivity of the Diamond-WC-Cu composite was investigated. After calculation, the interface thermal resistance of the composite forming the tungsten carbide transition layer is 2.11 × 10−8 m2∙K∙W−1. The thermal conductivity average value of the Diamond-WC-Cu composite with a diamond volume fraction of 60% reaches 874 W∙m−1∙K−1, which is close to the theoretical prediction value of Hasselman-Johnson (H-J) model and differential effective medium (DEM) model. Moreover, the Maxwell-Eucken (M-E) model, H-J model, and DEM model were used to evaluate the thermal conductivity of the Diamond-WC-Cu composite.
- Published
- 2021
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11. Investigation on Sub-Solvus Recrystallization Mechanisms in an Advanced γ-γ’ Nickel-Based Superalloy GH4151
- Author
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Shaomin Lv, Jinbin Chen, Xinbo He, Chonglin Jia, Kang Wei, and Xuanhui Qu
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GH4151 superalloy ,dynamic recrystallization ,gamma prime precipitates ,heteroepitaxial dynamic recrystallization ,step-shaped structures ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Sub-solvus dynamic recrystallization (DRX) mechanisms in an advanced γ-γ’ nickel-based superalloy GH4151 were investigated by isothermal compression experiments at 1040 °C with a strain rate of 0.1 s−1 and various true strain of 0.1, 0.3, 0.5, and 0.7, respectively. This has not been reported in literature before. The electron backscatter diffraction (EBSD) and transmission electron microscope (TEM) technology were used for the observation of microstructure evolution and the confirmation of DRX mechanisms. The results indicate that a new dynamic recrystallization mechanism occurs during hot deformation of the hot-extruded GH4151 alloy. The nucleation mechanism can be described as such a feature, that is a primary γ’ (Ni3(Al, Ti, Nb)) precipitate embedded in a recrystallized grain existed the same crystallographic orientation, which is defined as heteroepitaxial dynamic recrystallization (HDRX). Meanwhile, the conventional DRX mechanisms, such as the discontinuous dynamic recrystallization (DDRX) characterized by bulging grain boundary and continuous dynamic recrystallization (CDRX) operated through progressive sub-grain merging and rotation, also take place during the hot deformation of the hot-extruded GH4151 alloy. In addition, the step-shaped structures can be observed at grain boundaries, which ensure the low-energy surface state during the DRX process.
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- 2020
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12. Superplastic Deformation and Dynamic Recrystallization of a Novel Disc Superalloy GH4151
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Shaomin Lv, Chonglin Jia, Xinbo He, Zhipeng Wan, Xinxu Li, and Xuanhui Qu
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gh4151 alloy ,superplastic deformation ,activation energy ,dynamic recrystallization ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
The superplastic deformation of a hot-extruded GH4151 billet was investigated by means of tensile tests with the strain rates of 10−4 s−1, 5 × 10−4 s−1 and 10−3 s−1 and at temperatures at 1060 °C, 1080 °C and 1100 °C. The superplastic deformation of the GH4151 alloy was reported here for the first time. The results reveal that the uniform fine-grained GH4151 alloy exhibited an excellent superplasticity and high strain rate sensitivity (exceeded 0.5) under all experimental conditions. It was found that the increase of strain rate resulted in an increased average activation energy for superplastic deformation. A maximum elongation of 760.4% was determined at a temperature of 1080 °C and strain rate of 10−3 s−1. The average activation energy under different conditions suggested that the superplastic deformation with 1 × 10−4 s−1 in this experiment is mainly deemed as the grain boundary sliding controlled by grain boundary diffusion. However, with a higher stain rate of 5 × 10−4 s−1 and 1 × 10−3 s−1, the superplastic deformation is considered to be grain boundary sliding controlled by lattice diffusion. Based on the systematically microstructural examination using optical microscope (OM), SEM, electron backscatter diffraction (EBSD) and TEM techniques, the failure and dynamic recrystallization (DRX) nucleation mechanisms were proposed. The dominant nucleation mechanism of dynamic recrystallization (DRX) is the bulging of original grain boundaries, which is the typical feature of discontinuous dynamic recrystallization (DDRX), and continuous dynamic recrystallization (CDRX) is merely an assistant mechanism of DRX. The main contributions of DRX on superplasticity elongation were derived from its grain refinement process.
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- 2019
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13. Time-Domain Analytical Expression for Near Fields of Arbitrarily Oriented Electric Dipole and Its Application
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Qian Yang, Bing Wei, Xinbo He, and Minghao Gong
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Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Cellular telephone services industry. Wireless telephone industry ,HE9713-9715 - Abstract
The near fields of electric dipole are commonly used in wide-band analysis of complex electromagnetic problems. In this paper, we propose new near field time-domain expressions for electric dipole. The analytical expressions for the frequency-domain of arbitrarily oriented electric dipole are given at first; next we give the time-domain expressions by time-frequency transformation. The proposed expressions are used in hybrid TDIE/DGTD method for analysis of circular antenna with radome. The accuracy of the proposed algorithm is verified by numerical examples.
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- 2017
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14. Improvement in Mechanical and Thermal Properties of Graphite Flake/Cu Composites by Introducing TiC Coating on Graphite Flake Surface
- Author
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Ren Zhang, Xinbo He, Qian Liu, and Xuanhui Qu
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graphite flake ,composites ,interface ,thermal properties ,Mining engineering. Metallurgy ,TN1-997 - Abstract
In this work, TiC coating was successfully deposited on a graphite flake surface via molten salt technique, for the purpose of promoting the interfacial connection between Cu and graphite flake. Vacuum hot pressing was then employed to prepare TiC-coated graphite flake/Cu composite. The results indicate that introducing TiC coating on graphite flake surface can evidently reduce the pores and gaps at the interface, resulting in a significant improvement on the bending strength. When the TiC-coated graphite flake content is 60 vol%, the bending strength is increased by 58% compared with the uncoated one. The coefficient of thermal expansion dropped from 6.0 ppm·K−1 to 4.4 ppm·K−1, with the corresponding thermal conductivity as high as 571 W·m−1·K−1. The outstanding thermal conductivity, apposite coefficient of thermal expansion, as well as superior processability, make TiC-coated graphite flake/Cu composite a satisfactory electronic packaging material with vast prospect utilized in microelectronic industry.
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- 2019
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15. Improvement of ZrC/Zr Coating on the Interface Combination and Physical Properties of Diamond-Copper Composites Fabricated by Spark Plasma Sintering
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Yanpeng Pan, Xinbo He, Shubin Ren, Mao Wu, and Xuanhui Qu
- Subjects
diamond-copper ,composites ,coating ,sintering ,physical properties ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
In this study, diamond-copper composites were prepared with ZrC/Zr-coated diamond powders by spark plasma sintering. The magnetron sputtering technique was employed to coat the diamond particles with a zirconium layer. After heat treatment, most of the zirconium reacted with the surface of diamond and was transformed into zirconium carbide. The remaining zirconium on the zirconium carbide surface formed the outer layer. Owing to the method used to produce the ZrC/Zr-coated diamond in this study, the maximum thermal conductivity (TC) of 609 W·m−1·K−1 was obtained for 60 vol. % diamond-copper composites and the corresponding coefficient of thermal expansion (CTE) reached as low as 6.75 × 10−6 K−1. The bending strength of 40 vol. % ZrC/Zr-coated diamond-copper composites reached 255.95 MPa. The thermal and mechanical properties of ZrC/Zr-coated diamond-copper composites were substantially superior to those of uncoated diamond particles. Excellent properties can be attributed to the strengthening of the interfacial combination and the decrease in the interfacial thermal resistance due to the improvement associated with the ZrC/Zr coating. Theoretical analysis was also proposed to compare the thermal conductivities and CTE of diamond-copper composites fabricated with these two kinds of diamond powders.
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- 2019
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16. A Novel Exponential Time Delayed Fractional Grey Model and Its Application in Forecasting Oil Production and Consumption of China.
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Yong Wang 0032, Lei Zhang 0006, Xinbo He, Xin Ma 0004, Wenqing Wu, Rui Nie, Pei Chi, and Yuyang Zhang
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- 2023
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17. A novel fractional structural adaptive grey Chebyshev polynomial Bernoulli model and its application in forecasting renewable energy production of China.
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Yong Wang 0032, Rui Nie, Pei Chi, Xin Ma 0004, Wenqing Wu, Binhong Guo, Xinbo He, Lei Zhang 0006, and Yuyang Zhang
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- 2022
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18. A novel structure adaptive fractional discrete grey forecasting model and its application in China's crude oil production prediction.
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Yong Wang 0032, Lingling Ye, Zhongsen Yang, Xin Ma 0004, Wenqing Wu, Li Wang, Xinbo He, Lei Zhang 0006, Yuyang Zhang, Ying Zhou, and Yongxian Luo
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- 2022
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19. A novel fractional time-delayed grey Bernoulli forecasting model and its application for the energy production and consumption prediction.
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Yong Wang 0032, Xinbo He, Lei Zhang 0006, Xin Ma 0004, Wenqing Wu, Rui Nie, Pei Chi, and Yuyang Zhang
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- 2022
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20. A novel self-adaptive fractional multivariable grey model and its application in forecasting energy production and conversion of China.
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Yong Wang 0032, Li Wang, Lingling Ye, Xin Ma 0004, Wenqing Wu, Zhongsen Yang, Xinbo He, Lei Zhang 0006, Yuyang Zhang, Ying Zhou, and Yongxian Luo
- Published
- 2022
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21. 2-D Hybrid Cylindrical FDTD Method With Unconditional Stability
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Sihan Zhao, Bing Wei, Xinbo He, and Haochuan Deng
- Published
- 2023
22. The thermal and dielectric properties of diamond/SiC composites prepared by polymer impregnation and pyrolysis
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Pengfei Liu, Xinbo He, and Xuanhui Qu
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Inorganic Chemistry ,Renewable Energy, Sustainability and the Environment ,Process Chemistry and Technology ,Organic Chemistry ,Materials Chemistry ,Ceramics and Composites ,Energy Engineering and Power Technology - Published
- 2022
23. A Spatial Modes Filtering FETD Method Combined With Domain Decomposition for Simulating Fine Electromagnetic Structures
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Kaihang Fan, Bing Wei, Juan Chen, and Xinbo He
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Electrical and Electronic Engineering ,Condensed Matter Physics - Published
- 2022
24. Research on maximizing the diamond content of diamond/SiC composite
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Xinbo He, Zijian Zhang, Pengfei Liu, Pengfei Zhu, Hongda Guan, Jingyang Nan, and Xuanhui Qu
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Materials Chemistry ,Ceramics and Composites - Published
- 2022
25. A hybrid algorithm for electromagnetic problems involving fine structures based on FDTD and FETD with unstable modes removing
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Xinbo He, Bing Wei, and Kaihang Fan
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General Engineering ,General Physics and Astronomy - Published
- 2022
26. A Novel Exponential Time Delayed Fractional Grey Model and Its Application in Forecasting Oil Production and Consumption of China
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Yong Wang, Lei Zhang, Xinbo He, Xin Ma, Wenqing Wu, Rui Nie, Pei Chi, and Yuyang Zhang
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Artificial Intelligence ,Software ,Information Systems - Published
- 2022
27. Improved FDTD Method for Coupling Analysis of a Dielectric-Coated Wire Above Rough Soil Surface Under HPEM Pulse
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Wei Tian, Bing Wei, and Xinbo He
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Electrical and Electronic Engineering ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics - Published
- 2022
28. Ti6Al4V alloy fabricated by gelcasting based on low-oxygen gel system using hydride-dehydride titanium alloy powders
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Shao Yanru, Zhou Yang, Yanli Sui, Cunguang Chen, Fang Yang, Xinbo He, and Zhimeng Guo
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chemistry.chemical_compound ,Materials science ,Polyvinyl butyral ,chemistry ,Impurity ,Hydride ,General Chemical Engineering ,Ultimate tensile strength ,Slurry ,Titanium alloy ,Sintering ,Adhesive ,Composite material - Abstract
Oxygen and carbon impurity residues and low density are the main issues for Ti gelcasting. To overcome these difficulties, this study develops a low-oxygen isoprene (Ip)/polyvinyl butyral (PVB) gel system to achieve Ti gelcasting using hydride-dihydride (HDH) Ti6Al4V powder. Slurries with 48 vol% solid loading content are employed to achieve moulding followed by cold isostatic pressing. During gelcasting, powder particles are held in place by the cross-linking of Ip monomer with PVB as adhesive to maintain shape. After sintering, nearly fully dense (4.38 g/cm3) Ti6Al4V alloys with low interstitial contamination (O: 0.356 wt%, C: 0.14 wt%) are successfully fabricated. The samples exhibit acceptable mechanical performance, with ultimate tensile strength of 1062 MPa, yield strength of 987 MPa, and elongation of 8.75%. Typical plastic fracture with river patterns is observed, which is distinctly different from that of HEMA based sample.
- Published
- 2022
29. Numerical simulation of thermal conductivity of graphite flake/Cu composites with interfacial characteristics
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Jingyang Nan, Xinbo He, Zhang Tao, Xuanhui Qu, and Haiqing Yin
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Mechanics of Materials ,Mechanical Engineering ,Materials Chemistry ,Metals and Alloys - Published
- 2023
30. Anaerobic Passivation Behavior of Titanium Powder Via Sncl4-Ti Gas-Solid Fluidization Reaction
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Fang Yang, Yanli Li, Yanru Shao, Xinbo He, Cunguang Chen, and Zhimeng Guo
- Published
- 2023
31. Line-of-shower trigger method to lower energy threshold for GRB detection using LHAASO-WCDA
- Author
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C. F. Feng, Bin Zhou, X. L. Ji, R. Lu, H. B. Xiao, J. R. Shi, W. Zeng, Z. H. Wang, Shengxue Zhang, Pak-Hin Thomas Tam, H. C. Li, Jun Liu, H. Y. Jia, B. D'Ettorre Piazzoli, W. X. Wu, Junjie Mao, Y. Q. Guo, Dong Liu, F. Ji, H. R. Wu, Y. J. Wei, Alejandro Sáiz, Oleg Shchegolev, L. Feng, V. Rulev, L. Xue, Xuliang Chen, Xing-Yuan Hou, D. M. Wei, S. Hu, M. L. Chen, Jianeng Zhou, J. Y. Liu, Warit Mitthumsiri, Y. Zhang, Q. An, Y. He, Q. Gao, Ruizhi Yang, X. N. Sun, H. B. Hu, H. Liu, L. Chen, X. G. Wang, S. Q. Xi, J. Fang, X. H. You, Ping Zhou, Z. C. Huang, Y. Z. Li, P. F. Zhang, C. Y. Wu, Hong-Guang Wang, G. M. Xiang, W. Liu, Yu-Lei Chen, Zihuang Cao, X. C. Chang, Z. K. Zeng, Y. J. Bi, H. D. Liu, Y. D. Cheng, Bo Zhang, Y. Zheng, L. Q. Yin, Duo Yan, F. Zheng, Hao Zhou, X. X. Zhou, Q. Yuan, Hefan Li, J. F. Chang, Z. X. Liu, Felix Aharonian, H. N. He, C. D. Gao, Lei Zhao, Q. H. Chen, Youping Li, Y. M. Ye, B. B. Li, Yongchun Wang, Y. D. Cui, Bai Yibing, L. P. Wang, J. B. Zhao, Y. J. Wang, J. Y. Yang, S. Z. Chen, Yunchao Liu, B. Z. Dai, Rong Xu, Z. X. Fan, Z. Y. You, Z. G. Dai, X. F. Wu, He Zhang, S. H. Feng, S. B. Yang, J. J. Xia, W. Gao, S. L. He, Y. P. Wang, B. M. Chen, Fan Yang, A. Masood, Kun Fang, S.H. Chen, Yugang Zhang, H. Cai, Lang Shao, H. Wang, J.W. Xia, L. Z. Zhao, G. C. Xiao, X. X. Zhai, Y. C. Nan, Shi-Qi Hu, X. J. Bi, Z. Li, R. Liu, E. W. Liang, X. Zuo, M. J. Yang, Y. H. Yao, W. L. Li, L. X. Zhang, H. K. Lv, Xufang Li, B. Y. Pang, Zebo Tang, M. H. Gu, Z. Y. Pei, Xuejiao Li, F. R. Zhu, T. L. Chen, Qie Sun, K. J. Zhu, Ying Zhang, H. M. Zhang, J. Chen, H. L. Dai, Y. L. Xin, T. Wen, S. W. Cui, M. Zha, J. C. He, W. H. Huang, L. X. Bai, Binyu Zhao, Yun-Feng Liang, Jixia Li, X. H. Cui, Xinbo He, K. Jiang, X. J. Hu, J. W. Zhang, Li-Sheng Geng, Wenwu Tian, Z. X. Wang, Xiaofei Zhang, David Ruffolo, Yu. V. Stenkin, C. Hou, Z. B. Sun, Shuibin Lin, Lu Zhang, K. Levochkin, Cheng Guang Zhu, X. D. Sheng, Minghao Qi, Houdun Zeng, Jun-Jie Wei, Jia Zhang, Y. A. Han, H. B. Li, Danzengluobu, Rui Zhang, H. C. Song, Linbin Yang, Y. Z. Fan, J. T. Cai, H. H. He, Y. M. Xing, F. Y. Li, D. H. Huang, H. Zhu, Xiang Zhang, M. M. Ge, J. G. Guo, S. R. Zhang, N. Cheng, L. L. Ma, G. H. Gong, J. S. Wang, Cunguo Wang, Shujuan Liu, N. Yin, Y. H. Yu, W. J. Long, Axikegu, Xuelong Wang, P. P. Zhang, Chunlong Li, Minghui Liu, D. Bastieri, Jinyao Liu, Z. G. Yao, X. H. Ma, M. Heller, K. Li, Z. J. Jiang, J. Liu, R. N. Wang, V. I. Stepanov, Jian Wang, Chiming Jin, D.A. Kuleshov, G. G. Xin, M. J. Chen, S. P. Zhao, Y. Y. Guo, Donglian Xu, X. L. Guo, X. J. Dong, Y. K. Hor, T. Montaruli, Y. L. Feng, W. Wang, P. Pattarakijwanich, S. Wu, B. D. Wang, C. X. Liu, Y. W. Bao, X. T. Huang, R. Zhou, L. Y. Wang, D. della Volpe, C. W. Yang, Jun-Hui Fan, Zujian Wang, Q. B. Gou, Qizhi Huang, B. Liu, Bingshui Gao, Xiang-Yu Wang, Tao Zeng, and Bin Ma
- Subjects
Physics ,Nuclear and High Energy Physics ,Cherenkov detector ,Astrophysics::High Energy Astrophysical Phenomena ,Detector ,Astrophysics ,law.invention ,Air shower ,Nuclear Energy and Engineering ,Duty cycle ,law ,Observatory ,Gamma-ray burst ,Energy (signal processing) ,Line (formation) - Abstract
Observation of high energy and very high emission from Gamma Ray Bursts (GRBs) is crucial to study the gigantic explosion and the underline processes. With a large field-of-view and almost full duty cycle, the Water Cherenkov Detector Array (WCDA), a sub-array of the Large High Altitude Air Shower Observatory (LHAASO), is appropriate to monitor the very high energy emission from unpredictable transients such as GRBs. Nevertheless, the main issue for an extensive air shower array is the high energy threshold which limits the horizon of the detector. To address this issue a new trigger method is developed in this article to lower the energy threshold of WCDA for GRB observation. The proposed method significantly improves the detection efficiency of WCDA for gamma-rays around the GRB direction at 10-300 GeV. The sensitivity of the WCDA for GRB detection with the new trigger method is estimated. The achieved sensitivity of the quarter WCDA array above 10 GeV is comparable with that of Fermi-LAT. The data analysis process and corresponding fluence upper limit for GRB 190719C is presented as an example.
- Published
- 2021
32. A Subgridding Unconditionally Stable FETD Method Based on Local Eigenvalue Solution
- Author
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Xinbo He, Kaihang Fan, and Bing Wei
- Subjects
Physics::Fluid Dynamics ,Matrix (mathematics) ,Computer science ,Applied mathematics ,Symmetric matrix ,Electrical and Electronic Engineering ,Temporal discretization ,Multiscale modeling ,Finite element method ,Eigenvalues and eigenvectors ,Eigendecomposition of a matrix ,Matrix decomposition - Abstract
A subgridding unconditionally stable finite-element time-domain method based on local eigenvalue solution (SUSL-FETD) is proposed to solve multiscale modeling. In this method, subgridding elements are used to discrete a multiscale computational domain, and the explicit central-difference method is applied for temporal discretization. Compared with traditional elements, the subgridding elements have a more complex distribution of edges and nodes. Therefore, an efficient subgridding scheme is given to form the element matrix for each subgridding element. Such system matrices assembled by all element matrices are symmetric. The subgridding FETD (S-FETD) is then further developed into the subgridding unconditionally stable FETD (SUS-FETD) by filtering spatial unstable modes. It is time-consuming to obtain the unstable modes by global eigenvalue decomposition. In this article, the local eigenvalue decomposition is proposed to get the unstable modes, which further reduces the memory storage and computing time. Numerical examples certify that the proposed SUSL-FETD has high accuracy and efficiency.
- Published
- 2021
33. Radiation force and torque on an absorptive electromagnetic conductor sphere by an arbitrary-shaped optical polarized beam
- Author
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Huan Tang, Renxian Li, Shuhong Gong, Liu Yang, Lixia Yang, Bing Wei, Zitong Zhu, F.G. Mitri, Xiaotong Guo, and Xinbo He
- Subjects
Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials - Published
- 2023
34. Ultrahigh-energy photons up to 1.4 petaelectronvolts from 12 γ-ray Galactic sources
- Author
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Alejandro Sáiz, Y. H. Yao, W. X. Wu, P. P. Zhang, Zhuo Li, R. Liu, Pak-Hin Thomas Tam, H. C. Li, Liang Chen, J. C. Wang, Y. L. Xin, L. Chen, M. J. Chen, Hong-Guang Wang, Y. J. Wei, S. Hu, Junjie Mao, Y. Q. Guo, J. Y. Liu, V. Rulev, P. F. Zhang, L. Xue, H. B. Hu, H. Liu, Rui Zhang, Linbin Yang, C. F. Feng, F. Ji, Xiaofei Zhang, F. Zheng, V. I. Stepanov, Ping Zhou, Q. H. Chen, H. R. Wu, Warit Mitthumsiri, X. C. Chang, Z. K. Zeng, C. D. Gao, Bin Zhou, W. L. Li, S. Z. Chen, M. M. Ge, Lei Zhao, Y. Z. Li, Y. Y. Guo, Y. J. Bi, Zhe Cao, Y. K. Hor, Xuejiao Li, H. D. Liu, S. H. Feng, B. Liu, Y. D. Cheng, Bo Zhang, H. K. Lv, H. M. Zhang, K. Levochkin, Y. J. Wang, L. X. Bai, Jixia Li, T. Montaruli, Duo Yan, Hefan Li, Ying Zhang, Bingshui Gao, Q. An, H. B. Xiao, J. R. Shi, X. D. Sheng, Z. X. Liu, W. H. Huang, M. L. Chen, Jianeng Zhou, Q. Gao, Minghao Qi, W. Zeng, Li-Sheng Geng, J. Chen, B. M. Chen, T. Wen, S. W. Cui, Z. X. Wang, Chiming Jin, S. B. Yang, L. Z. Zhao, C. W. Yang, J. B. Zhao, D.A. Kuleshov, Y. M. Xing, L. P. Wang, E. W. Liang, X. F. Wu, Zhe Li, B. Y. Pang, B. B. Li, X. Zuo, Cong Li, S. Q. Xi, Kun Fang, W. Gao, B. Z. Dai, Z. H. Wang, H. Cai, Jun Liu, Zhen Wang, J. C. He, Houdun Zeng, J. Fang, G. C. Xiao, Y. C. Nan, Z. G. Yao, Z. Y. Pei, Jun-Hui Fan, X. X. Zhou, Q. Yuan, H. B. Li, Shi-Qi Hu, G. G. Xin, J. F. Chang, Xufang Li, Oleg Shchegolev, G. M. Xiang, S. P. Zhao, W. Liu, X. L. Ji, M. J. Yang, H. H. He, R. Lu, Zhengguo Cao, Felix Aharonian, J. W. Zhang, H. C. Song, Yongchun Wang, Yugang Zhang, Wenwu Tian, He Zhang, Bai Yibing, S. L. He, Donglian Xu, Y. L. Feng, Zebo Tang, X. L. Guo, Y. D. Cui, X. J. Dong, Zheng Wang, Jun-Jie Wei, Q. B. Gou, Qizhi Huang, H. N. He, K. J. Zhu, M. Zha, B. D. Wang, Ruizhi Yang, X. N. Sun, Y. P. Wang, Z. C. Huang, H. L. Dai, H. Wang, Xiang Zhang, Xing-Yuan Hou, Yunchao Liu, H. Y. Jia, D. M. Wei, Z. G. Dai, Rong Xu, Fan Yang, A. Masood, F. Y. Li, Xinbo He, Youping Li, X. T. Huang, L. Y. Wang, X. R. Li, J. J. Xia, K. Jiang, Binyu Zhao, X. J. Hu, Yun-Feng Liang, W. Wang, Y. A. Han, J. G. Guo, Yu. V. Stenkin, Lang Shao, J.W. Xia, P. Pattarakijwanich, X. H. You, S.H. Chen, S. R. Zhang, C. Hou, Shuibin Lin, Lu Zhang, L. Feng, Xuelong Wang, S. Wu, X. X. Zhai, Xuliang Chen, C. X. Liu, L. L. Ma, Y. He, Z. X. Fan, Z. Y. You, F. R. Zhu, Y. W. Bao, Qie Sun, Yi Chen, X. G. Wang, Yi Zhang, Xiang-Yu Wang, D. H. Huang, R. Zhou, Hao Zhou, H. Zhu, X. J. Bi, D. della Volpe, Tao Zeng, T. L. Chen, Bin Ma, J. S. Wang, Cunguo Wang, L. X. Zhang, Shujuan Liu, N. Yin, N. Cheng, D. Bastieri, X. H. Cui, Cheng Li, W. J. Long, Shengxue Zhang, Axikegu, Li Zhang, G. H. Gong, Danzengluobu, M. H. Gu, Y. H. Yu, Jie Zhang, Y. Z. Fan, Dong Liu, C. Y. Wu, J. T. Cai, Long Chen, Y. Zheng, L. Q. Yin, Y. M. Ye, J. Y. Yang, B D Ettorre Piazzoli, David Ruffolo, Z. B. Sun, Cheng Guang Zhu, X. H. Ma, M. Heller, K. Li, Z. J. Jiang, J. Liu, Yong Zhang, Minghui Liu, R. N. Wang, and Jinyao Liu
- Subjects
Physics ,Multidisciplinary ,Photon ,COSMIC cancer database ,Proton ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Electron ,Astrophysics ,01 natural sciences ,Galaxy ,Supernova ,Crab Nebula ,Pulsar ,0103 physical sciences ,010306 general physics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
The extension of the cosmic-ray spectrum beyond 1 petaelectronvolt (PeV; 1015 electronvolts) indicates the existence of the so-called PeVatrons—cosmic-ray factories that accelerate particles to PeV energies. We need to locate and identify such objects to find the origin of Galactic cosmic rays1. The principal signature of both electron and proton PeVatrons is ultrahigh-energy (exceeding 100 TeV) γ radiation. Evidence of the presence of a proton PeVatron has been found in the Galactic Centre, according to the detection of a hard-spectrum radiation extending to 0.04 PeV (ref. 2). Although γ-rays with energies slightly higher than 0.1 PeV have been reported from a few objects in the Galactic plane3–6, unbiased identification and in-depth exploration of PeVatrons requires detection of γ-rays with energies well above 0.1 PeV. Here we report the detection of more than 530 photons at energies above 100 teraelectronvolts and up to 1.4 PeV from 12 ultrahigh-energy γ-ray sources with a statistical significance greater than seven standard deviations. Despite having several potential counterparts in their proximity, including pulsar wind nebulae, supernova remnants and star-forming regions, the PeVatrons responsible for the ultrahigh-energy γ-rays have not yet been firmly localized and identified (except for the Crab Nebula), leaving open the origin of these extreme accelerators. Observations of γ-rays with energies up to 1.4 PeV find that 12 sources in the Galaxy are PeVatrons, one of which is the Crab Nebula.
- Published
- 2021
35. 3D gel printing of VC reinforced high vanadium high-speed steel
- Author
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Fang Yang, Qian Qin, Sun Haixia, Zhimeng Guo, Cunguang Chen, and Xinbo He
- Subjects
Materials science ,Metals and Alloys ,General Engineering ,Vanadium ,chemistry.chemical_element ,Microstructure ,Flexural strength ,Machining ,chemistry ,Slurry ,Surface roughness ,Relative density ,Composite material ,High-speed steel - Abstract
Due to their high hardness and high strength, VC reinforced hard materials such as high vanadium high-speed steel (HVHSS) are not suitable for machining to obtain complex shape with low cost. Therefore, 3D gel printing (3DGP) was employed to print HVHSS parts, using highly loaded slurry with 60% solid content as printing slurry. After printing parameters optimization, the printing sample had good surface quality, and obvious printing lines were observed. The extruded filament was in-situ cured, thus enough to maintain the designed shape. Uniform sintering shrinkage with a shrinkage rate of about 15% was obtained in the as-sintered sample with relative density of 99%. The surface roughness decreased from 6.5 µm to 3.8 µm. Fine carbides (
- Published
- 2021
36. Reach on the preparation process of diamond/SiC composites with bimodal diamond particle
- Author
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Zijian Zhang, Xinbo He, Tao Zhang, Pengfei Liu, Hongda Guan, Xulei Wang, and Xuanhui Qu
- Subjects
Polymers and Plastics ,Mechanics of Materials ,Materials Chemistry ,Ceramics and Composites - Published
- 2023
37. Preparation of high thermal conductivity diamond/SiC composites with 3D connected diamond at low volume fraction
- Author
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Pengfei Liu, Xinbo He, and Xuanhui Qu
- Subjects
Polymers and Plastics ,Mechanics of Materials ,Materials Chemistry ,Ceramics and Composites - Published
- 2023
38. Exploring the relationship between lattice distortion and phase stability in a multi-principal element alloy system based on machine learning method
- Author
-
Jiaxin Huang, Wei Fang, Congcong Xue, Tiexu Peng, Haoyang Yu, Jia Li, Liying Sun, Xinbo He, Baoxi Liu, Yong Yang, and Fuxing Yin
- Subjects
Computational Mathematics ,General Computer Science ,Mechanics of Materials ,General Physics and Astronomy ,General Materials Science ,General Chemistry - Published
- 2023
39. An Explicit Newmark-FDTD Algorithm With Subgridding Technique
- Author
-
Xinbo He, Kaihang Fan, and Bing Wei
- Subjects
Discretization ,Computer science ,Finite difference method ,Finite-difference time-domain method ,020206 networking & telecommunications ,02 engineering and technology ,Neumann series ,Matrix (mathematics) ,0202 electrical engineering, electronic engineering, information engineering ,Applied mathematics ,Newmark-beta method ,Electrical and Electronic Engineering ,Series expansion ,Coefficient matrix - Abstract
We address the electromagnetic problem involving small structures, and put forward an improved, explicit finite-difference time-domain (FDTD) algorithm based on the Newmark discretization with subgridding technique. This algorithm achieves a stable, low-reflection, and straightforward subgridding with an arbitrary grid refinement ratio by adopting hanging variables. The Newmark method is employed to discretize the numerical system generated by the subgridding method. Besides, the Neumann series is used to obtain the inverse of the coefficient matrix. It makes the time-marching explicit and stable with a uniform large time step only determined by the coarse grid size in the whole computational domain. The series expansion avoids the matrix inversion operation, which largely enhances the calculation efficiency compared to the traditional Newmark-FDTD method. Numerical results prove the reliability and robustness of the proposed method.
- Published
- 2020
40. Direct ink writing of TiC–316L metal matrix composites with an epoxy resin–absolute ethanol system
- Author
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Yuan Jiayun, Li Wenyuan, Jin Liuping, Huiping Shao, Tao Lin, Xin Deng, Fucheng Yu, and Xinbo He
- Subjects
Materials science ,Scanning electron microscope ,Metals and Alloys ,Epoxy ,Condensed Matter Physics ,Microstructure ,Matrix (chemical analysis) ,Flexural strength ,visual_art ,Materials Chemistry ,visual_art.visual_art_medium ,Surface roughness ,Slurry ,Relative density ,Physical and Theoretical Chemistry ,Composite material - Abstract
TiC–316L metal matrix composites were successfully printed with an epoxy resin–absolute ethanol system by direct ink writing (DIW) process in this study. Microstructure and fracture morphology of the samples were observed by a scanning electron microscope (SEM). Also, the relative density, hardness and transverse rupture strength (TRS) of the sintered samples were tested. The results show that the samples prepared with a new epoxy resin–absolute ethanol system by the DIW process have high solid content of printing slurry, good surface roughness, high relative density and high strength. The solid content of the slurry suitable for DIW was 60 vol%, and the internal diameter of the nozzle was set to 0.4 mm, the printing speed was set to 30 mm·s−1, and the layer height was set to 0.36 mm. For the sample with 35 wt% TiC–316L, the relative density, hardness and TRS of the sintered sample can reach 99.3%, HRA 79.5 and 1438 MPa, respectively.
- Published
- 2020
41. Preparation of CaB6 powder via calciothermic reduction of boron carbide
- Author
-
Guo-Hua Zhang, Yu Wang, Yue-Dong Wu, and Xinbo He
- Subjects
Phase transition ,Materials science ,Morphology (linguistics) ,Mechanical Engineering ,Metals and Alloys ,Analytical chemistry ,Boron carbide ,C content ,Grain size ,Carbide ,chemistry.chemical_compound ,chemistry ,Geochemistry and Petrology ,Mechanics of Materials ,Materials Chemistry ,Particle size ,Calcium hexaboride - Abstract
The method of calciothermic reduction of B4C was proposed for preparing CaB6. The phase transition and morphology evolution during the reaction were investigated in detail. The experimental results reveal that Ca first reacts with B4C to generate CaB2C2 and CaB6 at a low temperature and that the CaB2C2 subsequently reacts with Ca to produce CaB6 and CaC2 at a high temperature. After the products were leached to remove the byproduct CaC2, pure CaB6 was obtained. The grain size of the prepared CaB6 was 2–3 μm, whereas its particle size was 4–13 μm; it inherited the particle size of B4C. The residual C content of the product was decreased to 1.03wt% after the first reaction at 1173 K for 4 h and the second reaction at 1623 K for 4 h.
- Published
- 2020
42. A Hybrid FETD Algorithm for Electromagnetic Modeling of Fine Structures
- Author
-
Xinbo He, Kaihang Fan, Bing Wei, Yiwen Li, and Xiaolong Wei
- Subjects
Computer science ,Boundary (topology) ,020206 networking & telecommunications ,02 engineering and technology ,Time step ,Finite element method ,Domain (software engineering) ,0202 electrical engineering, electronic engineering, information engineering ,Computational electromagnetics ,Electrical and Electronic Engineering ,Time marching ,Algorithm ,Eigenvalues and eigenvectors ,Numerical stability - Abstract
A novel hybrid finite-element time-domain (FETD) algorithm is proposed to solve electromagnetic modeling with fine structures. This algorithm is based on the unconditionally stable FETD (US-FETD) and the traditional FETD methods. The US-FETD is used in the subdomain containing all fine grids and parts of coarse grids adjacent to the fine grids. The traditional FETD is applied in the other subdomain. A compensation and correction scheme is used to update the fields on the subdomain boundary. The hybrid FETD can make the explicit time marching unconditionally stable with a uniform time step determined by the coarse grids in the entire computational domain. In addition, the unstable modes of the entire system in the hybrid FETD can be effectively obtained by solving the partial solutions of the eigenvalue problem in the US-FETD subdomain. In comparison with the US-FETD in the entire computational domain, the eigenvalue analysis costs less memory and time. Numerical results certify the high efficiency of the hybrid FETD.
- Published
- 2019
43. A novel fractional structural adaptive grey Chebyshev polynomial Bernoulli model and its application in forecasting renewable energy production of China
- Author
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Yong Wang, Rui Nie, Pei Chi, Xin Ma, Wenqing Wu, Binhong Guo, Xinbo He, Lei Zhang, and Yuyang Zhang
- Subjects
Artificial Intelligence ,General Engineering ,Computer Science Applications - Published
- 2022
44. A novel structure adaptive new information priority discrete grey prediction model and its application in renewable energy generation forecasting
- Author
-
Xinbo He, Yong Wang, Yuyang Zhang, Xin Ma, Wenqing Wu, and Lei Zhang
- Subjects
General Energy ,Mechanical Engineering ,Building and Construction ,Management, Monitoring, Policy and Law - Published
- 2022
45. A novel structure adaptive fractional discrete grey forecasting model and its application in China’s crude oil production prediction
- Author
-
Yong Wang, Lingling Ye, Zhongsen Yang, Xin Ma, Wenqing Wu, Li Wang, Xinbo He, Lei Zhang, Yuyang Zhang, Ying Zhou, and Yongxian Luo
- Subjects
Artificial Intelligence ,General Engineering ,Computer Science Applications - Published
- 2022
46. Searching for an additional high-energy component in Fermi-LAT GRB afterglows
- Author
-
Yong Zhang, Guang-Bo Long, Xinbo He, Pak-Hin Thomas Tam, Li-Jun Zhang, and Partha Sarathi Pal
- Subjects
High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,High energy ,Photon ,Component (thermodynamics) ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Spectral line ,Afterglow ,Space and Planetary Science ,Gamma-ray burst ,Astrophysics - High Energy Astrophysical Phenomena ,Fermi Gamma-ray Space Telescope ,Energy component - Abstract
The VHE component from at least two GRBs, i.e., GRB180720B and GRB190114C, has been detected in the afterglow phase. We systematically analyzed 199 GRBs detected by Fermi-LAT during 2008-2019. If an additional high-energy component exists in the afterglows of Fermi-LAT GRBs, the best-fit spectral model could be a broken power-law (BPL) model with an upturn above a break energy. We compare the afterglow spectra using PL and BPL representations. Out of the 30 GRBs with >10GeV photons that arrived after T90, 25 GRBs are tentatively or significantly detected at 0.1-200 GeV after 2*T90. The spectrum of GRB131231A shows an upturn above a break of 1.6+-0.8~GeV, supporting the BPL model. For GRB131231A, we performed a modeling of its X-ray and gamma-ray spectra, and found that the SSC model can explain the upturn with acceptable parameter values. In the cases of GRBs 190114C, 171210A, 150902A, 130907A, 130427A, and 090902B, the improvement of the BPL fit compared to the PL fit is tentative or marginal. There is no conclusive evidence that an additional higher energy component commonly exists in Fermi-LAT GRB afterglows, except for a group of Fermi-LAT GRBs mentioned above. Such an additional high-energy component may be explained by the synchrotron self-Compton mechanism. Current and future VHE observations will provide important constraints on the issue., A\&A in press. arXiv admin note: substantial text overlap with arXiv:2002.08734
- Published
- 2021
47. Research on Hybrid Algorithm of Explicit Newmark-FDTD and Traditional FDTD Methods
- Author
-
Xinbo He, Bing Wei, and Kaihang Fan
- Subjects
Physics::Computational Physics ,Discretization ,Computer science ,Physics::Medical Physics ,Finite difference method ,Finite-difference time-domain method ,Physics::Optics ,Applied mathematics ,Computational electromagnetics ,Newmark-beta method ,Coefficient matrix ,Hybrid algorithm ,Neumann series - Abstract
The Newmark method is used to discretize the subgridding numerical system, and explicit Newmark-FDTD method is obtained by employing the Neumann series to expand the inverse of the coefficient matrix. Furthermore, the hybrid algorithm of explicit Newmark-FDTD and traditional FDTD methods is employed to further improve the computational efficiency.
- Published
- 2021
48. Discovery of a new $\gamma$-ray source LHAASO J0341+5258 with emission up to 200TeV
- Author
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Zhengguo Cao, L. Feng, Xufang Li, Zebo Tang, Jun-Jie Wei, C. Y. Wu, Jia Zhang, L. X. Bai, Yi Zhang, H. K. Lv, Jixia Li, L. L. Yang, Z. X. Wang, M. Zha, Y. M. Ye, X. H. Ma, L. P. Wang, X. G. Wang, Donglian Xu, X. L. Guo, Y. A. Han, Binyu Zhao, Yun-Feng Liang, Houdun Zeng, Zhe Li, Y. Su, B. Z. Dai, Z. G. Dai, Jinmei Liu, B. D'Ettorre Piazzoli, Z. G. Yao, Y. Zheng, W. X. Wu, M. L. Chen, Jianeng Zhou, Hefan Li, W. Wang, P. Pattarakijwanich, Rong Xu, J. J. Xia, X. X. Zhai, J. Fang, F. R. Zhu, Qie Sun, Yi Chen, H. B. Li, G. M. Xiang, W. Liu, B. Y. Pang, S. Wu, X. L. Ji, R. Lu, K. Li, Y. J. Bi, H. D. Liu, Y. D. Cheng, Bo Zhang, L. Q. Yin, Hanzhong Zhang, C. X. Liu, D. della Volpe, Y. D. Cui, Kun Fang, Yugang Zhang, E. W. Liang, Ping Zhou, Z. J. Jiang, Y. J. Wei, J. Liu, Yong Zhang, Duo Yan, Yu. V. Stenkin, S. L. He, Y. P. Wang, Z. X. Liu, D. H. Huang, R. N. Wang, S. M. Liu, F. Ji, V. Rulev, Y. Z. Li, H. H. He, H. Zhu, C. Hou, Zheng Wang, B. Q. Ma, Y. C. Nan, L. Xue, Jun Liu, Lu Zhang, H. Y. Jia, D. M. Wei, V. I. Stepanov, E. S. Chen, Sina Chen, K. J. Zhu, Y. Q. Qi, Fulai Guo, J. Y. Shi, Minghui Liu, Yi Liu, J. B. Zhao, H. Wang, X. F. Wu, Zhen Wang, Z. X. Fan, Z. Y. You, Shi-Qi Hu, J. Y. Yang, N. Cheng, Z. K. Zeng, C. D. Gao, X. H. You, Long Gao, H. C. Song, Lei Zhao, D.A. Kuleshov, X. X. Zhou, Q. Yuan, B. M. Chen, Ruizhi Yang, X. N. Sun, Shengxue Zhang, Danzengluobu, J. F. Chang, S. P. Zhao, H. Liu, J.W. Xia, W. Gao, G. C. Xiao, Felix Aharonian, Xinbo He, K. Jiang, Pak-Hin Thomas Tam, H. C. Li, Y. Wang, Y. Z. Fan, Dong Liu, Y. W. Bao, P. F. Zhang, X. J. Bi, H. N. He, T. L. Chen, L. Z. Zhao, X. J. Hu, R. Zhou, Ying Zhang, Oleg Shchegolev, Junjie Mao, Y. Q. Guo, F. Y. Li, K. Levochkin, J. T. Cai, X. D. Sheng, Cong Li, X. Zuo, B. B. Li, Long Chen, Yunchao Liu, H. L. Dai, T. Wen, S. W. Cui, S. Z. Chen, David Ruffolo, Y. M. Xing, H. R. Wu, Liang Chen, Xiang-Kun Dong, S. Hu, J. Y. Liu, X. Y. Huang, P. P. Zhang, X. H. Cui, Minghao Qi, Z. B. Sun, Y. Bai, Z. Y. Pei, Cheng Guang Zhu, Yuan-Hao Wang, Zhuo Li, Warit Mitthumsiri, H. M. Zhang, Q. An, Y. H. Yao, W. H. Huang, H. Zhou, W. J. Long, Binbin Zhou, Li-Sheng Geng, R. Liu, Xiang Zhang, J. G. Guo, J. W. Zhang, S. R. Zhang, Wenwu Tian, L. L. Ma, Q. Gao, C. F. Feng, Jiangang He, J. S. Wang, Cunguo Wang, Y. L. Xin, Z. C. Huang, H. B. Hu, N. Yin, B. Q. Qiao, Xin Li, Cheng Li, Jiajun Qin, M. H. Gu, Boyang Wang, Rui Zhang, H. B. Xiao, W. Zeng, L. X. Zhang, S. H. Feng, M. M. Ge, Axikegu, Yonggang Wang, M. J. Chen, Zhao-Qi Wang, Y. Y. Guo, Li Zhang, G. H. Gong, Zhe Cao, Y. K. Hor, Y. H. Yu, T. Montaruli, Jian Wang, Chiming Jin, Z. Min, Xuelong Wang, G. G. Xin, Kai-Kai Duan, D. Bastieri, Y. L. Feng, T. Ke, S. J. Lin, X. T. Huang, L. Y. Wang, B. Liu, Jingzhi Yan, Bingshui Gao, Xiang-Yu Wang, Yulong Li, Tao Zeng, Xuliang Chen, Y. He, C. W. Yang, Jun-Hui Fan, Q. B. Gou, W. L. Li, D. X. Xiao, Qizhi Huang, J. Chen, Xiao-Hu Zhang, H. Cai, M. J. Yang, S. Q. Xi, Hong-Guang Wang, Alejandro Sáiz, Q. H. Chen, S. B. Yang, Fan Yang, A. Masood, F. Zheng, Lang Shao, and M. Heller
- Subjects
Physics ,Astrophysics::High Energy Astrophysical Phenomena ,Hadron ,Gamma ray ,Flux ,Astronomy and Astrophysics ,Astrophysics ,Galactic plane ,Crab Nebula ,Pulsar ,Space and Planetary Science ,Angular diameter ,High Energy Physics::Experiment ,Supernova remnant ,Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics::Galaxy Astrophysics - Abstract
We report the discovery of a new unidentified extended $\gamma$-ray source in the Galactic plane named LHAASO J0341+5258 with a pre-trial significance of 8.2 standard deviations above 25 TeV. The best fit position is R.A.$=55.34^{\circ}\pm0.11^{\circ}$ and Dec$=52.97^{\circ}\pm0.07^{\circ}$. The angular size of LHAASO J0341+5258 is $0.29^\circ \pm 0.06^\circ_{stat} \pm0.02^\circ_{sys}$. The flux above 25 TeV is about $20\%$ of the flux of Crab Nebula. Although a power-law fit of the spectrum from 10 TeV to 200 TeV with the photon index $\alpha=2.98 \pm 0.19_{stat} \pm 0.02_{sys}$ is not excluded, the LHAASO data together with the flux upper limit at 10 GeV set by the Fermi LAT observation, indicate a noticeable steepening of an initially hard power-law spectrum %($\alpha \leq 1.75$) spectrum with a cutoff at $\approx 50$ TeV. We briefly discuss the origin of UHE gamma-rays. The lack of an energetic pulsar and a young SNR inside or in the vicinity of LHAASO J0341+5258 challenge, but do not exclude both the leptonic and hadronic scenarios of gamma-ray production., Comment: Accepted by APJL
- Published
- 2021
49. The Optimization of Ti Gradient Porous Structure Involves the Finite Element Simulation Analysis
- Author
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Xuanhui Qu, Lijia Guo, Mingying Chen, Jiaqi Dong, Chaozong Liu, Yitong Liu, Zhang Jiazhen, Maryam Tamaddon, Wei Xu, Xin Lu, Xinbo He, and Liu Bowen
- Subjects
Technology ,Materials science ,Materials Science (miscellaneous) ,medicine.medical_treatment ,0206 medical engineering ,chemistry.chemical_element ,oral implants ,02 engineering and technology ,Bone tissue ,bone stress ,medicine ,titanium ,Composite material ,Dental implant ,Porosity ,Stress concentration ,Bone growth ,three-dimensional finite element simulation ,Stress–strain curve ,021001 nanoscience & nanotechnology ,020601 biomedical engineering ,medicine.anatomical_structure ,chemistry ,Implant ,gradient porosity ,0210 nano-technology ,Titanium - Abstract
Titanium (Ti) and its alloys are attracting special attention in the field of dentistry and orthopedic bioengineering because of their mechanical adaptability and biological compatibility with the natural bone. The dental implant is subjected to masticatory forces in the oral environment and transfers these forces to the surrounding bone tissue. Therefore, by simulating the mechanical behavior of implants and surrounding bone tissue we can assess the effects of implants on bone growth quite accurately. In this study, dental implants with different gradient pore structures that consisted of simple cubic (structure a), body centered cubic (structure b) and side centered cubic (structure c) were designed, respectively. The strength of the designed gradient porous implant in the oral environment was simulated by three-dimensional finite element simulation technique to assess the mechanical adaptation by the stress-strain distribution within the surrounding bone tissue and by examining the fretting of the implant-bone interface. The results show that the maximum equivalent stress and strain in the surrounding bone tissue increase with the increase of porosity. The stress distribution of the gradient implant with a smaller difference between outer and inner pore structure is more uniform. So, a-b type porous implant exhibited less stress concentration. For a-b structure, when the porosity is between 40 and 47%, the stress and strain of bone tissue are in the range of normal growth. When subject to lingual and buccal stresses, an implant with higher porosity can achieve more uniform stress distribution in the surrounding cancellous bone than that of low porosity implant. Based on the simulated results, to achieve an improved mechanical fixation of the implant, the optimum gradient porous structure parameters should be: average porosity 46% with an inner porosity of 13% (b structure) and outer porosity of 59% (a structure), and outer pore sized 500 μm. With this optimized structure, the bone can achieve optimal ingrowth into the gradient porous structure, thus provide stable mechanical fixation of the implant. The maximum equivalent stress achieved 99 MPa, which is far below the simulation yield strength of 299 MPa.
- Published
- 2021
50. Graphite addition for SiC formation in diamond/SiC/Si composite preparation
- Author
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Dandan Guan, Xuanhui Qu, Rong-jun Liu, Mao Wu, Xinbo He, and Zheng Wei
- Subjects
Materials science ,Silicon ,Scanning electron microscope ,Mechanical Engineering ,Composite number ,0211 other engineering and technologies ,Metals and Alloys ,chemistry.chemical_element ,Diamond ,02 engineering and technology ,engineering.material ,021001 nanoscience & nanotechnology ,Thermal expansion ,Thermal conductivity ,chemistry ,Geochemistry and Petrology ,Mechanics of Materials ,Volume fraction ,Materials Chemistry ,engineering ,Graphite ,Composite material ,0210 nano-technology ,021102 mining & metallurgy - Abstract
Herein, graphite was used in the Si-vapor reactive infiltration of diamond/SiC/Si composites to produce composites with various SiC contents. X-ray diffraction was used to determine the phases of the composite, whereas scanning electron microscopy was used to confirm the Si–C reaction between the silicon, graphite, and diamond and to observe the SiC morphology. Various SiC contents in the composite were observed with graphite addition. Furthermore, the reaction between silicon and graphite (diamond) produced coarse (fine) SiC particles. The generation of a 10-μm-diameter Si–C area on the surface of the diamond was observed. The thermal conductivity (TC) and coefficient of thermal expansion (CTE) of the composite was investigated, where the TC varied from 317–426 W•m−1•K−1 with the increase of the SiC volume fraction from 38% to 76% and the corresponding CTE increased from 1.7 × 10-6 to 3.7 × 10−6 K−1, respectively. Furthermore, a critical point for the CTE was found to exist at approximately 250°C, where the composite was under a hydrostatic condition. Finally, the bending strength was found to range from 241 to 341 MPa.
- Published
- 2019
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