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Temperature dependence of single-event transients in SiGe heterojunction bipolar transistors for cryogenic applications

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Chinese Physics B 2023年第9期32卷 535-544页

作者：潘霄宇郭红霞冯亚辉刘以农张晋新付军喻国芳 The Key Laboratory of Particle and Radiation Imaging Ministry of EducationDepartment of Engineering PhysicsTsinghua UniversityBeijing 100084China State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Northwest Institute of Nuclear TechnologyXi'an 710024China School of Material Science and Engineering Xiangtan UniversityXiangtan 411105China School of Aerospace Science and Technology Xidian UniversityXi'an 710126China School of Integrated Circuits Tsinghua UniversityBeijing 100084China

We experimentally demonstrate that the dominant mechanism of single-event transients in silicon-germanium heterojunction bipolar transistors(SiGe HBTs)can change with decreasing temperature from+20℃to-180℃.This is accomplished by using a new well-designed cryogenic experimental system suitable for a pulsed-laser ***,when the temperature drops from+20℃to-140℃,the increased carrier mobility drives a slight increase in transient ***,as the temperature decreases further below-140℃,the carrier freeze-out brings about an inflection point,which means the transient amplitude will decrease at cryogenic *** better understand this result,we analytically calculate the ionization rates of various dopants at different temperatures based on Altermatt's new incomplete ionization *** parasitic resistivities with temperature on the charge-collection pathway are extracted by a two-dimensional(2D)TCAD process *** addition,we investigate the impact of temperature on the novel electron-injection process from emitter to base under different bias *** increase of the emitter-base junction's barrier height at low temperatures could suppress this electron-injection *** have also optimized the built-in voltage equations of a high current compact model(HICUM)by introducing the impact of incomplete *** present results and methods could provide a new reference for effective evaluation of single-event effects in bipolar transistors and circuits at cryogenic temperatures,and could provide a new evidence of the potential of SiGe technology in applications in extreme cryogenic environments.

关键词： SiGe heterojunction bipolar transistors pulsed laser TCAD simulation single-event transient

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Dilated Convolutional Pixels Affinity Network for Weakly Supervised Semantic Segmentation

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Chinese Journal of Electronics 2021年第6期30卷 1120-1130页

作者： ZHANG Zhe WANG Bilin YU Zhezhou LI Zhiyuan College of Computer Science and Technology Jilin University Key Laboratory for Symbol Computation and Knowledge Engineering of National Education Ministry

This paper studies semantic segmentation primarily under image-level weak-supervision. Most stateof-the-art technologies have recently used deep classification networks to create small and sparse discriminatory seed regions of each interest target as pseudo-labels for training segmentation networks, which achieve inferior performance compared with the fully supervised *** propose a Dilated convolutional pixels affinity network(DCPAN) to localize and expand the seed regions of objects to bridge this gap. Although introduced dilated convolutional units enable capture of additional location information of objects, it falsely highlighted true negative regions as dilated rate enlarge. To address this problem,we properly integrate dilated convolutional units with different dilated rates and self-attention mechanisms to obtain pixel affinity measure matrix for promoting classification network to generate high-quality object seed regions as pseudo-labels; thus, the performance of the segmentation network is boosted. Furthermore,although our approach seems simple, our method obtains a competitive performance, and experiments show that the performance of DCPAN outperforms other state-ofart approaches in weakly-supervised settings, which only use image-level labels on the Pascal VOC 2012 dataset.

关键词： weakly supervised semantic segmentation pseudolabels deep classification networks high-quality object seed regions pattern classification image segmentation weakly-supervised settings dilated convolutional pixels affinity network image-level weak-supervision image classification DCPAN self-attention mechanism object recognition feature extraction object detection sparse discriminatory seed regions pixel affinity measure matrix Pascal VOC 2012 dataset

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Purification efficiency of ecological spur dikes for river pollutants in different geometric arrangements:Experiments and numerical modeling

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Journal of Hydrodynamics 2022年第5期34卷 934-947页

作者： Yi-tian Chen Xiao-ling Wang Song-min Li Ya-zhi Zheng Guang-yao Dong College of Environmental Science and Engineering Tianjin UniversityTianji300350China State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin300072China College of Hydraulic Engineering Tianjin Agricultural CollegeTianjin300392China

The traditional ecological spur dike is improved,by using the biological fillers such as the plant materials,combined with microorganisms,to obtain a larger water purification *** of the researches on spur dikes focused on the hydrodynamic force and the migration and the diffusion of the pollutants,but not so much on the effects of the spur dike materials and the arrangement parameters on the water purification *** this paper the biological zeolite is used to make ecological spur *** laboratory flume experiment shows that compared with the natural zeolite spur dike,the purification effect of the biological zeolite spur dike is significantly improved,and the average removal rate of the NH3-N is kept at 6.8%after 24 h compared with 3.5%of the natural zeolite spur *** NH3-N removal rates of a single spur dike,the counterpart spur dikes and the staggered spur dikes decrease with the increase of the inlet flow,and the staggered spur dikes have the best purification ***,a numerical model based on the MIKE21 is verified by the experimental results and applied for the Tangjiali Section of the Xutangqiao River in Xinwu District,Wuxi City,Jiangsu *** orthogonal test shows that the length of the spur dike has the most important effect on the interception of pollutants and the purification,followed by the angle of the spur dike and the spacing of the spur dikes has the least important *** geometric arrangement parameters of the ecological spur dike group with the highest efficiency on the pollutant interception and the purification are:60°(angle),6.7 m(length)and 20 m(spacing).

关键词： Ecological spur dike spur dike group numerical simulation biological zeolite interception purification geometric arrangement parameters

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Supertetragonal BaZrS_(3):A promising perovskite sulphide with giant ferroelectricity and low band gap

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science China(Physics,Mechanics & Astronomy) 2024年第8期67卷 126-133页

作者： Menglu Li Sa Zhang Chenhan Liu Xiaotao Zu Liang Qiao Haiyan Xiao School of Physics University of Electronic Science and Technology of ChinaChengdu 611731China College of Mathematics and Physics Chengdu University of TechnologyChengdu 610059China Micro-and Nano-scale Thermal Measurement and Thermal Management Laboratory Ministry of Education Key Laboratory of Numerical Simulation of Large-Scale Complex SystemsSchool of Energy and Mechanical EngineeringNanjing Normal UniversityNanjing 210023China

Over the past century,ferroelectricity has offered exciting opportunities for fundamental research and device ***,most of the discovered excellent ferroelectrics are oxide materials with large band gaps,limiting their potential for optoelectronics *** using first-principles calculations we identify a new narrow-gap ferroelectric beyond oxides,i.e.,ferroelectric perovskite sulphide BaZrS_(3).Under large compressive strains,BaZrS_(3)can be stabilized into a unique supertetragonal phase with an extraordinary polarization of 67.16μC/cm^(2),which is even stronger than that of conventional oxide ***,the supertetragonal BaZrS_(3)exhibits a direct narrow band gap of 1.2 eV and excellent electronic *** on the chemical bonding analysis,we attribute the formation of supertetragonal phase to charge re-ordering in which theπbond overlap along the long〈Zr-S〉bond completely vanishes and the antibonding states of theσbond appear below the Fermi *** work provides a conceptual strategy for designing new ferroelectrics for electronic and photovoltaic applications.

关键词： supertetragonal phase perovskite sulphide ferroelectricity

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A NEURAL MULTIGRID SOLVER FOR HELMHOLTZ EQUATIONS WITH HIGH WAVENUMBER AND HETEROGENEOUS MEDIA

arXiv

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arXiv 2024年

作者： Cui, Chen Jiang, Kai Shu, Shi Hunan Key Laboratory for Computation and Simulation in Science and Engineering Key Laboratory of Intelligent Computing and Information Processing Ministry of Education School of Mathematics and Computational Science Xiangtan University Hunan Xiangtan411105 China

In this paper, we propose a deep learning-enhanced multigrid solver for high-frequency and heterogeneous Helmholtz equations. By applying spectral analysis, we categorize the iteration error into characteristic and non-characteristic components. We eliminate the non-characteristic components by a multigrid wave cycle, which employs carefully selected smoothers on each grid. We diminish the characteristic components by a learned phase function and the approximate solution of an advection-diffusion-reaction (ADR) equation, which is solved using another multigrid V-cycle on a coarser scale, referred to as the ADR cycle. The resulting solver, termed Wave-ADR-NS, enables the handling of error components with varying frequencies and overcomes constraints on the number of grid points per wavelength on coarse grids. Furthermore, we provide an efficient implementation using differentiable programming, making Wave-ADR-NS an end-to-end Helmholtz solver that incorporates parameters learned through a semi-supervised training. Wave-ADR-NS demonstrates robust generalization capabilities for both in-distribution and out-of-distribution velocity fields of varying difficulty. Comparative experiments with other multigrid methods validate its superior performance in solving heterogeneous 2D Helmholtz equations with wavenumbers exceeding *** Codes 65N22, 65N55, 68T07 Copyright © 2024, The Authors. All rights reserved.

关键词： Helmholtz equation

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Pumping and sliding of droplets steered by a hydrogel pattern for atmospheric water harvesting

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National science Review 2023年第12期10卷 181-192页

作者： Wei Zhang Qinghua Ji Gong Zhang Zhenao Gu Haozhi Wang Chengzhi Hu Huijuan Liu Zhiyong Jason Ren Jiuhui Qu Center for Water and Ecology State Key Joint Laboratory of Environment Simulation and Pollution ControlSchool of Environment Tsinghua University Key Laboratory of Drinking Water Science and Technology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences University of Chinese Academy of Sciences Joint School of National University of Singapore and Tianjin University International Campus of Tianjin University Key Laboratory of Advanced Ceramics and Machining Technology(Ministry of Education) School of Materials Science and EngineeringTianjin University Department of Civil and Environmental Engineering and Andlinger Center for Energy and the Environment Princeton University

Atmospheric water harvesting is an emerging strategy for decentralized and potable water supplies. However,water nucleation and microdroplet coalescence on condensing surfaces often result in surface flooding owing to the lack of a sufficient directional driving force for shedding. Herein, inspired by the fascinating properties of lizards and catfish, we present a condensing surface with engineered hydrogel patterns that enable rapid and sustainable water harvesting through the directional pumping and drag-reduced sliding of water droplets. The movement of microscale condensed droplets is synergistically driven by the surface energy gradient and difference in Laplace pressure induced by the arch hydrogel patterns. Meanwhile, the superhydrophilic hydrogel surface can strongly bond inner-layer water molecules to form a lubricant film that reduces drag and facilitates the sliding of droplets off the condensing surface. Thus, this strategy is promising for various water purification techniques based on liquid–vapor phase-change processes.

关键词： atmospheric water harvesting droplet manipulation bio-inspired condensation

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Convergent analysis of algebraic multigrid method with data-driven parameter learning for non-selfadjoint elliptic problems

arXiv

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arXiv 2024年

作者： Zhang, Juan Luo, Junyue Key Laboratory of Intelligent Computing and Information Processing of Ministry of Education Hunan Key Laboratory for Computation and Simulation in Science and Engineering School of Mathematics and Computational Science Xiangtan University Hunan Xiangtan411105 China

In this paper, we apply the practical GADI-HS iteration as a smoother in algebraic multigrid (AMG) method for solving second-order non-selfadjoint elliptic problem. Additionally, we prove the convergence of the derived algorithm and introduce a data-driven parameter learing method called Gaussian process regression (GPR) to predict optimal parameters. Numerical experimental results show that using GPR to predict parameters can save a significant amount of time cost and approach the optimal parameters accurately. © 2024, CC BY.

关键词： Algebra

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Ultrathin organic solvent nanofiltration membrane with polydopamine-HKUST-1 interlayer for organic solvent separation

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Journal of Environmental sciences 2024年第7期141卷 182-193页

作者： Haike Li Xindong Li Guozai Ouyang Lijinhong Huang Lang Li Wenhao Li Wanfu Huang Duokun Li Ganzhou Key Laboratory of Basin Pollution Simulation and Control Jiangxi University of Science and TechnologyGanzhou 341000China Innovation Center for Water Quality Security Technology at Ganjiang River Basin Jiangxi University of Science and TechnologyGanzhou 341000China School of Architecture and Design Jiangxi University of Science and TechnologyGanzhou 341000China WA School of Mines:Minerals Energy and Chemical EngineeringCurtin UniversityWA 6845Australia School of Materials Science and Engineering Tiangong UniversityTianjin 300387China

Polydopamine(PDA)and metal-organic skeleton HKUST-1 were co-deposited on the base membrane of hexamethylenediamine(HDA)-crosslinked polyetherimide(PEI)ultrafiltration membrane as the interlayer,and high-throughput organic solvent nanofiltration membrane(OSN)was prepared by interfacial polymerization and solvent activation *** polyamide(PA)layer surface roughness from 28.4 nm in PA/PEI to 78.3 nm in PA/PDA-HKUST-10.6/PEI membrane,reduced the thickness of the separation layer from 79 to 14 nm,and significantly improved the hydrophilic,thermal and mechanical *** flux of the PA/PDA-HKUST-10.6/PEI membrane in a 0.1 g/L Congo Red(CR)ethanol solution at 0.6 MPa test pressure reached 21.8 L/(m^(2)·hr)and the rejection of CR was 92.8%.Solvent adsorption test,N,N-dimethylformamide(DMF)immersion experiment,and long-term operation test in ethanol showed that the membranes had high solvent *** solvent flux test demonstrated that,under the test pressure of 0.6 MPa,the flux of different solvents ranked as follows:methanol(56.9 L/(m^(2)·hr))>DMF(39.6 L/(m^(2)·hr))>ethanol(31.2 L/(m^(2)·hr))>IPA(4.5 L/(m^(2)·hr))>N-hexane(1.9 L/(m^(2)·hr)).The ability of the membranes to retain dyes in IPA/water dyes solution was also *** flux of the membrane was 30.4 L/(m^(2)·hr)and the rejection of CR was 91.6%when the IPA concentration reached 50%.This OSN membrane-making strategy is economical,environment-friendly and efficient,and has a great application prospect in organic solvent separation systems.

关键词： Interfacial polymerization Organic solvent nanofiltration Interlayer Metal-organic frameworks Polydopamine

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Approaches for Resilience Assessment of Steel Catenary Riser Based on Dynamic Bayesian Networks 34th

Approaches for Resilience Assessment of Steel Catenary Riser...

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34th International Ocean and Polar engineering Conference, ISOPE 2024

作者： Chang, Xueying Zhang, Zhengwei Yu, Yang Wu, Jingyi Cao, Qun China Ship Scientific Research Center Wuxi China Taihu Laboratory of Deepsea Technology Science Wuxi China State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin University Tianjin China

ISBN: (纸本)9781880653784

The steel catenary riser (SCR), being a crucial component that connects subsea oil and gas resources to surface storage and transportation facilities, can result in significant losses when damaged. Traditional risk assessment methods typically focus solely on the reliability of the riser system. However, the recoverability from a failure is of equally importance due to the economics and environmental concerns. To assess both the reliability and recoverability of the riser, the resilience assessment methodology is proposed. The resilience assessment process is divided into two parts, namely degradation process and recovery process, both of which are calculated through Dynamic Bayesian Networks (DBN). © 2024 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： Risk assessment

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Momentum-Accelerated Richardson(m) and Their Multilevel Neural Solvers

arXiv

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arXiv 2024年

作者： Wang, Zhen Liu, Yun Cui, Chen Shu, Shi Hunan Key Laboratory for Computation and Simulation in Science and Engineering Key Laboratory of Intelligent Computing and Information Processing of Ministry of Education School of Mathematics and Computational Science Xiangtan University Hunan Xiangtan411105 China

Recently, designing neural solvers for large-scale linear systems of equations has emerged as a promising approach in scientific and engineering computing. This paper first introduce the Richardson(m) neural solver by employing a meta network to predict the weights of the long-step Richardson iterative method. Next, by incorporating momentum and preconditioning techniques, we further enhance convergence. Numerical experiments on anisotropic second-order elliptic equations demonstrate that these new solvers achieve faster convergence and lower computational complexity compared to both the Chebyshev iterative method with optimal weights and the Chebyshev semi-iteration method. To address the strong dependence of the aforementioned single-level neural solvers on PDE parameters and grid size, we integrate them with two multilevel neural solvers developed in recent years. Using alternating optimization techniques, we construct Richardson(m)FNS for anisotropic equations and NAG-Richardson(m)-WANS for the Helmholtz equation. Numerical experiments show that these two multilevel neural solvers effectively overcome the drawback of single-level methods, providing better robustness and computational efficiency. Copyright © 2024, The Authors. All rights reserved.

关键词： Iterative methods

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