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Signal-background discrimination with convolutional neural networks in the PandaX-Ⅲ experiment using MC simulation

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Science China(Physics,Mechanics & Astronomy) 2018年第10期61卷 51-59页

作者： Hao Qiao ChunYu Lu Xun Chen Ke han XiangDong Ji SiGuang Wang School of Physics and State Key Laboratory of Nuclear Physics and Technology and Center for High Energy Physics Peking University Beijing 100871 China Institute of Particle and Nuclear Physics and School of Physics and Astronomy Shanghai Jiao Tong University Shanghai Laboratory for Particle Physics and Cosmology Shanghai 200240 China Tsung-Dao Lee Institute Shanghai 200240 China

The PandaX-Ⅲ experiment will search for neutrinoless double beta decay of 136Xe with high pressure gaseous time projection chambers at the China Jin-Ping underground Laboratory. The tracking feature of gaseous detectors helps suppress the background level, resulting in the improvement of the detection sensitivity. We study a method based on the convolutional neural networks to discriminate double beta decay signals against the background from high energy gammas generated by 214Bi and 2^208 T1 decays based on detailed Monte Carlo simulation. Using the 2-dimensional projections of recorded tracks on two planes, the method successfully suppresses the background level by a factor larger than 100 with a high signal efficiency. An improvement of 62% on the efficiency ratio of Еs/√Еb is achieved in comparison with the baseline in the PandaX-Ⅲ conceptual design report.

关键词： neutrino double beta decay convolutional neural networks background suppression

Rationally designed carbon-coated Fe304 coaxial nanotubes with hierarchical porosity as high-rate anodes for lithium ion batteries

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Nano Research 2014年第11期7卷 1706-1717页

作者： Fei han Lingjuan Ma Qiang sun Cheng Lei Anhui Lu State Key Laboratory of Fine Chemicals School of Chemical Engineering Dalian University of Technology Dalian 116024 China State Key Laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 China School of Chemistry and Chemical Engineering Qufu Normal University Qufu 273165 China

Fe3O4 is a promising high-capacity anode material for lithium ion batteries, but challenges including short cycle life and low rate capability hinder its widespread implementation. In this work, a well-defined tubular structure constructed by carbon-coated Fe3O4 has been successfully fabricated with hierarchically porous structure, high surface area, and suitable thickness of carbon layer. Such purposely designed hybrid nanostructures have an enhanced electronic/ionic conductivity, stable electrode/electrolyte interface, and physical buffering effect arising from the nanoscale combination of carbon with Fe3O4, as well as the hollow, aligned and hierarchically porous architectures. When used as an anode material for a lithium-ion half cell, the carbon-coated hierarchical Fe3O4 nanotubes showed excellent cycling performance with a specific capacity of 1,020 mAh.g^-1 at 200 mA.g^-1 after 150 cycles, a capacity retention of ca. 103%. Even at a higher current density of 1,000 mA·g^-1, a capacity of 840 mAh·g^-1 is retained after 300 cycles with no capacity loss. In particular, a superior rate capability can be obtained with a stable capacity of 355 mAh.g^-1 at 8,000 mA·g^-1. The encouraging results indicate that hierarchically tubular hybrid nanostructures can have important implications for the development of high-rate electrodes for future rechargeable lithium ion batteries （LIBs）.

关键词： nanotube carbon Fe3O4 rate capability cycle stability

Modeling uniaxial tensile deformation of polycrystalline Al using CPFEM

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Journal of University of Science and Technology Beijing 2008年第1期15卷 43-47页

作者： Huachun pi Jingtao han Chuanguo Zhang A. Kiet Tieu Zhengyi Jiang School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China School of Mechanical Materials ＆ Mechatronic Engineering University of Wollongong Wollongong NSW 2522 Australia Sinosteel Scie-Tech Development Company Beijing 100080 China

The crystal plasticity finite element modeling （CPFEM） is realized in commercial finite element code ABAQUS with UMAT subroutine on the basis of the crystal plasticity theory of rate dependent polycrystal constitutive relations in the mesoscopic scale. The initial orientations obtained by electron backscatter diffraction （EBSD） are directly input into the CPFEM to simulate the mechanical response of polycrystalline 1050 pure Al in uniaxial tensile deformation. Two polycrystal models and two tensile strain rates were used in the simulations. The stress-strain curves of tensile deformation were analyzed. The predictions and the corresponding experiment result show reasonable agreement and slight deviation with experiments. The flow true stress of strain rate 0.01 s^-1 is higher than that of strain rate 0.001 s^-1. At the strain less than 0.05, the stress saturated rate of the experiment is higher than the simulated results. However, the stress saturated rate of the experiment becomes gentler than the corresponding simulated predictions at the strain over 0.05. Also, necking was simulated by the two models, but the necking strain is not well predicted. Tensile textures at strain 0.25 were predicted at the low strain rate of 0.001 s^-1. The predictions are in good accord with the experimental results. 2008 University of Science and Technology Beijing. All rights reserved.

关键词： crystal plasticity f'mite element method electron backscatter diffraction (EBSD) uniaxial tensile deformation

Review of Si IGBT and SiC MOSFET Based on Hybrid Switch

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Chinese Journal of Electrical Engineering 2019年第3期5卷 20-29页

作者： Puqi Ning Tianshu Yuan Yuhui Kang Cao han Lei Li Key Laboratory of Power Electronics and Electric Drive Institute of Electrical EngineeringChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100190China

SiC Hybrid switch(HyS)combines low conduction loss of Si IGBT and low switching loss of SiC MOSFET,and the cost is closer to that of Si *** promising high performances of HyS will bring considerable achievement in terms of enhancing power density of a converter *** reviewing the gate drive pattern,gate drive hardware,current sharing,module design,converter design,and cost,this paper introduces state-of-the-art SiC HyS.

关键词： Hybrid module SiC device Si IGBT SiC MOSFET

Coupled CUBIC Congestion Control for MPTCP in Broadband Networks

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Computer Systems Science & Engineering 2023年第4期45卷 99-115页

作者： Jae Yong Lee Byung Chul Kim Youngmi Kwon Kimoon han Department of Information and Communications Engineering Chungnam National UniversityDaejeon34134Korea Agency for Defense Development Daejeon34186Korea

Recently,multipath transmission control protocol(MPTCP)was standardized so that data can be transmitted through multiple paths to utilize all available path ***,when high-speed long-distance networks are included in MPTCP paths,the traffic transmission performance of MPTCP is severely deteriorated,especially in case the multiple paths’characteristics are heavily *** order to alleviate this problem,we propose a“Coupled CUBIC congestion control”that adopts TCP CUBIC on a large bandwidth-delay product(BDP)path in a linked increase manner for maintaining fairness with an ordinary TCP traversing the same bottleneck *** verify the performance excellence of the proposed algorithm,we implemented the Coupled CUBIC Congestion Control into Linux kernels by modifying the legacy MPTCP linked-increases algorithm(LIA)congestion control source *** constructed asymmetric heterogeneous network testbeds mixed with large and small BDP paths and compared the performances of LIA and Coupled CUBIC by *** results show that the proposed Coupled CUBIC utilizes almost over 80%of the bandwidth resource in the high BDP path,while the LIA utilizes only less than 20%of the bandwidth for the same *** was confirmed that the resource utilization and traffic transmission performance have been greatly improved by using the proposed Coupled CUBIC in high-speed multipath networks,as well as maintaining MPTCP fairness with competing single-path CUBIC or Reno TCP flows.

关键词： MPTCP congestion control Coupled CUBIC high BDP network

Evaluating a satellite-based sea surface temperature by shipboard survey in the Northwest Indian Ocean

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Acta Oceanologica Sinica 2016年第11期35卷 52-58页

作者： YANG Guang HE Hailun WANG Yuan han Xiqiu WANG Yejian Ocean College Zhejiang University State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyState Oceanic Administration Key Laboratory of Submarine Geosciences Second Institute of OceanographyState Oceanic Administration

A summer-time shipboard meteorological survey is described in the Northwest Indian Ocean. Shipboard observations are used to evaluate a satellite-based sea surface temperature（SST）, and then find the main factors that are highly correlated with errors. Two satellite data, the first is remote sensing product of a microwave, which is a Tropical Rainfall Measuring Mission Microwave Imager（TMI）, and the second is merged data from the microwave and infrared satellite as well as drifter observations, which is Operational Sea Surface Temperature and Sea Ice Analysis（OSTIA）. The results reveal that the daily mean SST of merged data has much lower bias and root mean square error as compared with that from microwave products. Therefore the results support the necessary of the merging infrared and drifter SST with a microwave satellite for improving the quality of the SST. Furthermore, the correlation coefficient between an SST error and meteorological parameters, which include a wind speed, an air temperature, a relative humidity, an air pressure, and a visibility. The results show that the wind speed has the largest correlation coefficient with the TMI SST error. However, the air temperature is the most important factor to the OSTIA SST error. Meanwhile,the relative humidity shows the high correlation with the SST error for the OSTIA product.

关键词： shipboard survey sea surface temperature Northwest Indian Ocean Tropical Rainfall Measuring Mission Microwave Imager Operational Sea Surface Temperature and Sea Ice Analysis

Aqueous-Phase Synthesis ofAg-TiO2-Reduced Graphene Oxide and Pt-TiO2-Reduced Graphene Oxide Hybrid Nanostructures and Their Catalytic Properties

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Nano Research 2011年第11期4卷 1153-1162页

作者： Ping Wang Lei han Chengzhou Zhu Yueming Zhai Shaojun Dong State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun130022 China

We demonstrate an aqueous solution method for the synthesis of a Ag-TiO2-reduced graphene oxide （rGO） hybrid nanostructure （NS） in which the Ag and TiO2 particles are well dispersed on the rGO sheet. The Ag-TiO2-rGO NS was then used as a template to synthesize Pt-TiO2-rGO NS. The resulting hybrid NSs were characterized by transmission electron microscopy （TEM）, high-resolution TEM （HRTEM）, energy-dispersive X-ray （EDX） spectroscopy, X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, Fourier transform infrared （FTIR） spectroscopy, UV-vis spectroscopy, Raman spectroscopy, inductively coupled plasma mass spectrometry （ICP-MS）, and catalytic studies. It was found that TiO2-rGO, Ag-TiO2-rGO and Pt-TiO2-rGO NSs all show catalytic activity for the reduction of p-nitrophenol to p-aminophenol by NaBH4, and that Pt-TiO2-rGO NS exhibits the highest catalytic activity as well as excellent stability and easy recyclability.

关键词： Reduced graphene oxide TiO2 silver platinum hybrid nanostructures catalytic

Lamb wave sensors array for nonviscous liquid sensing

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Science China(Physics,Mechanics & Astronomy) 2006年第4期49卷 461-472页

作者： CHEN Zhijun han Tao JI Xiaojun GUO Huawei SHI Wenkang Department of Instrumentation Engineering Shanghai Jiao Tong University Shanghai 200240 China Department of Instrumentation Engineering Shanghai Jiao Tong University Shanghai 200240 China Department of Instrumentation Engineering Shanghai Jiao Tong University Shanghai 200240 China Department of Instrumentation Engineering Shanghai Jiao Tong University Shanghai 200240 China Department of Instrumentation Engineering Shanghai Jiao Tong University Shanghai 200240 China

The interdigital transducer (IDT) can excite Lamb wave in a piezoelectric plate loading with a liquid layer, and the phase velocity of Lamb wave is associated with the properties of the liquid layer. In this paper, the concept of effective permittivity is introduced to study the Lamb wave's potential application in liquid sensing. Considering the measuring of ideal nonviscous liquid, the sensors array is designed to sense the density and the dielectric constant of the liquid layer simultaneously. Using LiNbO3 as piezoelectric material, in order to improve the sensors array sensitivity and the electro-mechanical coupling coefficient, the optimized results including plate thicknesses and cut orientations are presented by numerical simulation. These studies show that the Lamb wave sensors array can be potential in liquid sensing.

关键词： Lamb wave sensors array, density, dielectric constant, plate thickness, cut orientation.

Enhancement in light output power of LEDs with reflective current blocking layer and backside hybrid reflector

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Science China(Technological Sciences) 2013年第6期56卷 1544-1549页

作者： ZHOU ShengJun FANG Fang CAO Bin LIU Sheng DING han State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong University Quantum Wafer Inc. State Key Laboratory of Digital Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and Technology

A GaN-based light-emitting diode (LED) with reflective current blocking layer (CBL) underneath p-electrode pad and backside hybrid reflector was fabricated and investigated. With a 20 mA injection current, the LED with SiO2 /ITO/Al reflective CBL deposited on naturally textured p-InGaN/p-GaN surface exhibited a light output power that was 7.6% and 18.5% higher than those of the textured LEDs with SiO2 CBL and without SiO2 CBL, respectively. The LED with backside hybrid reflector exhibited a light output power that was 30% higher than that of LED without the hybrid reflector. The enhancement in light output power is attributed to the improved current spreading performance via the SiO2 CBL, the Al omnidirectional metal reflector to prevent the light absorption by the opaque p-electrode pad, and the backside hybrid reflector to extract bottom-emitting light.

关键词： LEDs reflective CBL hybrid reflector