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Research Square 2020年

作者： Li, Xiaoming Liao, Shijun Department of Earth Atmospheric and Planetary Sciences Massachusetts Institute of Technology CambridgeMA02139 United States MOE Key Laboratory of Disaster Forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University Guangzhou510632 China School of Physics and Astronomy Shanghai Jiaotong University Shanghai200240 China Center of Advanced Computing School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai200240 China

Triple systems are common and key objects in astronomy. The three-body problem has received much more attention in recent years1–3. All observed periodic triple stars systems4–6 belong to the Broucke-Hadjidemetriou-Hénon’s (BHH) family7–9. The BHH orbits are a family of periodic orbits of the three-body system with the simplest topological free group word10 a, while Janković and Dmitrašinović 1 gained 58 equal-mass BHH satellite orbits which have free group words ak (k > 1), where k is the topological exponent. However, the BHH satellite orbits with equal mass is lack of realistic meaning because they do not exist in practice. Here we present 419743 new BHH orbits and 179253 new BHH satellites (k > 1) for three-body system with unequal mass. Especially, 48761 among the 179253 new BHH satellites are stable and have unequal masses. It suggests that these 48761 stable BHH satellites could be found by the observation. Besides, for the three-body system with equal mass at a fixed energy, it was demonstrated that the relationship between the angular momentum (L) and topological scaled period (T/k) of the BHH satellites is the same as that of the BHH orbits1. However, we found that this does not hold for the three-body system with unequal mass. Our findings have broad impact for the astrophysical scenario: they could inspire the theoretical and observational study of the triple system, the formation of triple stars11, the gravitational waves pattern12 and the gravitational waves observation13 of the triple system. © 2020, CC BY.

关键词： Satellites

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Study on the optimum position of gas extraction in goaf of high position borehole based on CFD 7

Study on the optimum position of gas extraction in goaf of h...

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7th International Symposium on Project Management, ISPM 2019

作者： Yan, Baoyong Zhang, Xiaoze Li, Yibin Chongqing Research Institute of China Coal Technology and Engineering Group Chongqing400039 China State Key Lab. of Gas Disaster Monitoring and Control as well as Emergency Technology Chongqing400039 China College of Energy and Power Engineering Lanzhou University of Technology Lanzhou730050 China

ISBN: (纸本)9781921712692

In order to study the effect of gas extraction by high position borehole in goaf, and determine the best position of the borehole, it provides a reference for the selection of gas extraction target location by high position borehole in the future. Based on the goaf of 40113 working face of a mine in Fenxi Group of Shanxi Province, the gas migration model is established. and the gas extraction effect of high position borehole under different target strata is simulated by FLUENT. The results show that the gas concentration in the upper corner of the working face is reduced from 2.3% to 0.7% after using high position borehole to extract gas by compared with the non-extraction situation, which solves the problem of gas concentration exceeding the limit in the upper corner of the working face. When high position borehole of the distance from the floor of goaf is 26m,and the distance from the level of return air roadway is 25m, the gas concentration in the upper corner of the working face is 0.58%, and the gas concentration in the hole is the highest and the purity is the largest. © 2019 by Aussino Academic Publishing House.

关键词： Extraction

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Wave Soldering Coupled Thermal-mechanical Simulation of Multi-layer Ceramic Capacitors

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IOP Conference Series: Earth and Environmental Science 2021年第4期632卷

作者： Wei Su Wenhao Luo Junkui Li Renhuai Liu MOE Key lab of Disaster Forecast and Control in Engineering Guangzhou 510632 China. Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou 510610 China. School of Mechanics and Construction Engineering Jinan University Guangzhou 510632 China

In this paper, the thermal-mechanical coupling finite element analysis of MLCC wave soldering with heat conduction and heat convection is calculated, and the steady-state temperature field and transient temperature field as well as the stress distribution of MLCC are obtained. Using the finite element analysis method of indirect thermal-mechanical coupling, the stress analysis is carried out with the temperature field as the boundary condition, and the thermal-structural coupling model is established. By analyzing the thermal stress of MLCC, the weak parts sensitive to thermal stress are determined, which provides a useful reference for solving the reliability problem of MLCC wave soldering.

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Sensing and Exploiting Static Femto-Newton Optical Forces by a Nanofiber with White-Light Interferometry

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ACS PHOTONICS 2018年第8期5卷 3205-3213页

作者： Yu, Jianhui Chen, Liheng Dong, Huazhuo Liu, Xingyu Huang, Hankai Qiu, Weiqia Huang, Shiqing Zhu, Wenguo Lu, Huihui Tang, Jieyuan Xiao, Yi Zhong, Yongchun Luo, Yunhan Zhang, Jun Chen, Zhe Jinan Univ Guangdong Higher Educ Inst Key Lab Optoelect Informat & Sensing Technol Guangzhou 510632 Guangdong Peoples R China Jinan Univ Guangdong Prov Key Lab Opt Fiber Sensing & Commun Guangzhou 510632 Guangdong Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China

Optical force determines the fundamental process of momentum exchange between light and matter. However, owing to the weak mechanical effect of the optical force and relatively large stiffness of optomechanical devices, pico-Newton (10(-12) N) optical force is required to manipulate micro/nanoparticles and the optical response of optical devices. It is still extremely challenging to sense static femto-Newton (fN) optical forces and exploit such forces to actuate micro-optical devices. Here, using a tapered nanofiber (TNF) with a high mechanical efficiency of 2.13 nm/fN, a sensitive and cost-effective scheme is demonstrated to generate, sense, and exploit fN optical force. Strong light coupling from the TNF to a glass substrate can result in a fN repulsive optical force, which can induce a TNF deformation of up to 425.6 nm. Such a large deformation allows white-light interferometry to detect a fN static optical force (5.2 fN). Moreover, the high optomechanical efficiency (15.6 nm/mu W) allows us to all-optically control the signal power at values ranging from 0.09 to 17.1 mu W with only microwatt pump power, which paves the way toward microwatt and fN-optical-force optomechanical devices.

关键词： femto-Newton optical force all-optical control linear momentum exchange nanofiber white-light interferometry optomechanics

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Harmonic Response Analysis for Ball Grid Array Package Using Computer Finite Element Simulation

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Journal of Physics: Conference Series 2021年第1期2033卷

作者： Wei Su Wenhao Luo Xianshan Dong Si Chen Agam Tomar Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou China MOE Key lab of Disaster Forecast and Control in Engineering Guangzhou China School of Mechanics and Construction Engineering Jinan University Guangzhou China Faculty of Engineering and Mathematical Sciences University of Western Australia

BGA package is selected as the research object in this paper. Workbench (finite elemental analysis tool in ANSYS) is used for harmonic response analysis. The author lays several paper sheets on the sample and builds the finite element model of clamp, ceramic and metal plate. Then, the model analysis is carried out. Based on this, it is converted to harmonic response analysis. According to the results, the author has found that there is no relation between the number of paper sheets and acceleration-frequency result. It promotes the development of electronic packaging reliability.

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Dynamic compressive and splitting tensile response of unsaturated polyester polymer concrete material at different curing ages

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CONSTRUCTION AND BUILDING MATERIALS 2018年 177卷 477-498页

作者： Chen, De Liu, Feng Yang, Fei Jing, Lin Feng, Wanhui Lv, Jianbing Luo, Qingzi Guangdong Univ Technol Sch Civil & Transportat Engn Guangzhou 510006 Guangdong Peoples R China Southwest Jiaotong Univ State Key Lab Tract Power Chengdu 610031 Sichuan Peoples R China Jinan Univ Moe Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China

The present study performed quasi-static and dynamic compressive and splitting tensile tests on unsaturated polyester polymer concrete (UPPC) at four different curing ages (6 h, 3 days, 7 days, and 28 days). We examined a total of 136 specimens, specifically 24 cubic specimens and 12 cylindrical specimens for quasi-static tests and 45 cylinders and 55 FBD specimens for dynamic compressive and tensile tests, respectively. The experimental results indicated that UPPC exhibited rapid strength enhancement in the early stages of curing, and the natural curing condition-treated cubic specimens exhibited 6-h compressive and splitting tensile strengths of 40 MPa and 6.5 MPa, respectively, which was almost the 50-60% of the 28-day strengths. The UPPC is also sensitive to the strain rate, such that both the compressive and splitting tensile strengths exhibited significant increases following an increase in the strain rate. Conversely, the strain rate sensitivity decreased with the curing age. We deemed the CEB-FIP equation for normal cement concrete to be inadequate for estimating the strain rate sensitivity of UPPC. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： UPPC Curing age SHPB Flattened Brazilian disc Dynamic increase factor

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Experimental study on dynamic split tensile properties of rubber concrete

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CONSTRUCTION AND BUILDING MATERIALS 2018年 165卷 675-687页

作者： Feng, Wanhui Liu, Feng Yang, Fei Li, Lijuan Jing, Lin Guangdong Univ Technol Sch Civil & Transportat Engn Guangzhou 510006 Guangdong Peoples R China Jinan Univ Moe Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China Southwest Jiaotong Univ State Key Lab Tract Power Chengdu 610031 Sichuan Peoples R China

Static and dynamic split tensile tests were conducted on rubber concrete with varied volume fractions of rubber particles that replaced fine aggregate (10%, 20%, 30%, 40%, and 50%, named as RC10, RC20, RC30, RC40, and RC50, respectively). The flattened Brazilian disc specimens were applied to determine the tensile properties and energy absorption capabilities under high strain rate by an SHPB (Split Hopkinson Pressure Bar) and medium strain rate by a drop-hammer testing machine. With a high-speed camera, the crack growth of specimens in the SHPB and drop-hammer impacting tests was observed and validated. The experimental result of five rubber concretes and one normal concrete without rubber particles was obtained, and the strain-rate effect on tensile strength of rubber concretes and normal concrete was confirmed. For high strain rate, RC10, RC20 and RC30 were sensitive to strain rate dependence, but rate dependence of RC40 and RC50 was lower than normal concrete. RC30 exhibited the most sensitivity and excellent energy absorption capability in static and dynamic tests. Excessive rubber content did not continually increase the toughness of the concrete under dynamic loadings. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Dynamic split tensile test Rubber concrete Flattened Brazilian disc (FBD) Energy absorption capability

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Effect of water immersion pressure on oxidation characteristics and spontaneous combustion characteristics of long-flame coal

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Energy 2024年 291卷

作者： Lin Li Tiantian Liu Xiangjun Chen Yifan Huang Yongliang Xu Zhiqiang Li Lin Wang Lingling Qi Shufan Zhang Rongqing Zhang Xiangyang Ye College of Safety Science and Engineering Henan Polytechnic University Jiaozuo Henan 454003 China MOE Engineering Center of Mine Disaster Prevention and Rescue Henan Polytechnic University Jiaozuo Henan 454003 China Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization Henan Polytechnic University Jiaozuo Henan 454003 China Henan Provincial Key Lab of Gas Geology and Control-Cultivation Base of Provincial and Ministry Joint State Key Henan Polytechnic University Jiaozuo Henan 454003 China School of Engineering The University of Western Australia (UWA) Perth 6009 Australia

Coal seam water injection has an obvious effect on coal dust prevention. The high-pressure water environment of coal seam water injection changes the structure of coal which brings new effects on the characteristics of coal spontaneous combustion disaster. To reveal the effects of water immersion pressure on the oxidation characteristics of long-flame coal, coal samples immersed in water at 0.1 MPa, 2.5 MPa, 5.0 MPa, 7.5 MPa and 10.0 MPa were prepared. Four experiments were conducted to study the changes in oxidation characteristics and its main reasons. The results showed that elevated water immersion pressure promoted the spontaneous combustion tendency of coal, and the composite judgment index of coal decreased to 521.1. Coal immersed in pressurized water entered the stages of oxygen-absorbing oxidation and thermal decomposition earlier than coal immersed in atmospheric pressure water. The specific surface area and average pore diameter of coal immersed in high-pressure water increased, where the pore volume proportion of mesopores of the coal immersed in water at 10.0 MPa increased by 138.5 % compared with that of the coal immersed in atmospheric pressure water. The elevated water immersion pressure prompted coal to produce further aliphatic hydrocarbons and hydroxyl groups, which improved the low-temperature oxidation capacity.

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Study on Axial Compression Performance of GFRP Tube Reactive Power Concrete Composite Short Columns with Encased Steel

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IOP Conference Series: Earth and Environmental Science 2021年第1期676卷

作者： Jing Ji Huayu Song Liangqin Jiang Li Jiang Heilongjiang Key Lab of Disaster Prevention Mitigation and Protection Engineering Northeast Petroleum University Heilongjiang Daqing 163318 China Key Laboratory of Structural Disaster and Control of the Ministry of Education Harbin Institute of Technology Heilongjiang Harbin 150090 China Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering Mechanics China Earthquake Administration Harbin 150086 China

In order to study the axial compression performance of the GFRP tube reactive power concrete composite short column with encased steel, a finite element model of the composite short column was established. The constitutive models of steel, RPC and GFRP were selected. The element selection and contact method of each component were explained. The boundary condition and mesh division of the composite column were determined. Based on this, finite element verification analysis of 6 specimens was performed by ABAQUS. The load-displacement curves and the axial compression bearing capacity were obtained. By comparing with the test, the reasonability of the constitutive model and the finite element model of this kind of column is verified.

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Experimental Verification on Finite Element Model of Composite Columns with Concrete Filled Steel Tube Flange

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IOP Conference Series: Earth and Environmental Science 2021年第1期676卷

作者： Jing Ji Li Jiang Liangqin Jiang Huayu Song Heilongjiang Key Lab of Disaster Prevention Mitigation and Protection Engineering Northeast Petroleum University Heilongjiang Daqing 163318 China Key Laboratory of Structural Disaster and Control of the Ministry of Education Harbin Institute of Technology Heilongjiang Harbin 150090 China Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering Mechanics China Earthquake Administration Harbin 150086 China

In order to study mechanical performance of composite columns with concrete-filled steel tube flange subjected to the eccentric compression, the finite element model of this kind of composite columns is established by using ABAQUS finite element software. In this paper, the reasonable material constitutive and finite element modelling method are selected to carry out numerical simulation analysis of concrete-filled steel tubular composite columns and concrete-filled square steel tubular columns. The load vertical displacement curves, load lateral deflection curves and failure modes are obtained, which are in good agreement with the existing test data. The rationality of material constitutive and finite element modelling is verified, which lays a foundation for further establishing the calculation formula of eccentric compression bearing capacity of this kind of column.

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