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Evolution of microstructure and texture of AZ80 magnesium alloy under hot torsion with constant decreasing temperature rate

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Journal of Magnesium and Alloys 2024年第4期12卷 1619-1637页

作者： Yongbiao Yang Jinxuan Guo Cuiying Wang Wenxuan Jiang Zhimin Zhang Qiang Wang Xing Zhang College of Materials Science and Engineering North University of ChinaLane 3Xueyuan RoadTaiyuanShanxi 030051China North Hongyang mechanical and electronic limited company of Henan Province China

Hot torsion tests for AZ80 magnesium alloy were carried out in the temperature range of 380℃-260℃,with a constant decreasing temperature rate of 10℃/s in order to weaken the basal texture and refine the *** results indicated that the average grain sizes were refined forming gradient structure with increasing specimen radial position from center(12.2-5.4μm),and that the initial basal texture intensity of the extruded magnesium alloy was weakened from 46.2 to ***,the extension twins(ETs)could be disintegrated from the twins forming separated twins with smaller ***,ETs with the same twin variant intersecting with each other could be coalesced forming grains with similar orientation,while ETs with different twin variants were separated by twins boundaries contributing to grain ***,in addition to the conventional continuous dynamic recrystallized(CDRX)grains with 30˚orientation rotated around C-axis of the parent grains,CDRXed grains with 30˚rotation around a-axis and random rotation axis were also ***,the CDRX evolution induced twins were also elaborated,exhibiting the complex competition between CDRX and *** torsion deformation with constant decreasing temperatures rate is an effective way of grain refinement and texture modification.

关键词： Texture Microstructure Hot torsion Decreasing temperature AZ80

Distributed Nash Equilibrium Seeking on Compact Action Sets over Jointly Strongly Connected Switching Networks

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Journal of Systems Science & Complexity 2024年第1期37卷 63-81页

作者： HE Xiongnan HUANG Jie department of mechanical and Automation Engineering The Chinese University of Hong KongHong Kong 999077China.

This paper studies the distributed Nash equilibrium seeking(DNES)problem for games whose action sets are compact and whose network graph is switching satisfying the jointly strongly connected *** keep the actions of all players in their action sets all the time,one has to resort to the projected gradient-based *** the assumption that the unique Nash equilibrium is the unique equilibrium of the pseudogradient system,an algorithm is proposed that is able to exponentially find the Nash ***,the authors also consider the distributed Nash equilibrium seeking problem for games whose actions are governed by high-order integrator dynamics and belong to some compact *** examples are used to illustrate the proposed approach.

关键词： Compact action sets jointly strongly connected switching graphs Nash equilibrium seeking projected gradient-based algorithm.

Solid Desiccant Heat Pump Fresh Air Unit using Composite Silica Gel

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Journal of Thermal Science 2024年第4期33卷 1286-1300页

作者： YANG Tianyu GUO Defang GE Tianshu Institute of Refrigeration and Cryogenics Shanghai Jiao Tong UniversityKey Laboratory of Power Mechanical EngineeringMOE ChinaShanghai200240China Qingdao Haier A/C electronic Co. LtdQingdao266101China

The introduction of fresh air into the indoor space leads to a significant increase in cooling or heating *** desiccant heat pump fresh air unit which can handle the latent and sensible load of fresh air efficiently have been proposed *** improve the performance of the solid desiccant heat pump fresh air unit in the fresh air handling process,in this paper,the application of composite silica gel in a heat pump fresh air unit was *** comparison between silica gel coating(SGC)and composite silica gel coating(CSGC)shows that the adsorption rate and water uptake capacity of CSGC are more than two times higher than those of *** experimental setup for the solid desiccant heat pump fresh air unit was *** performance of SGC and CSGC was tested in the setup *** show that under summer conditions,compared with the solid desiccant heat pump fresh air unit using silica gel(SGFU),the average moisture removal and COP of the one using composite silica gel(CSGFU)increased by 15%and 30%,*** winter conditions,compared with SGFU,the average humidification and COP of CSGFU increased by 42%and 17%.With optimal operation conditions of 3 min switchover time and 40 r/s compressor frequency,the COP of CSGFU under summer conditions can reach *** also show that the CSGFU and SGFU have higher COP and dehumidification rate under higher outdoor temperature and humidity ratio.

关键词： fresh air system desiccant coated heat exchanger humidification dehumidification experimental comparison

On the use of deep learning for phase recovery

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Light(Science & Applications) 2024年第2期13卷 190-235页

作者： Kaiqiang Wang Li Song Chutian Wang Zhenbo Ren Guangyuan Zhao Jiazhen Dou Jianglei Di George Barbastathis Renjie Zhou Jianlin Zhao Edmund Y.Lam department of Electrical and electronic Engineering The University of Hong KongHong Kong SARChina School of Physical Science and Technology Northwestern Polytechnical UniversityXi’anChina department of Biomedical Engineering The Chinese University of Hong KongHong Kong SARChina School of Information Engineering Guangdong University of TechnologyGuangzhouChina department of mechanical Engineering Massachusetts Institute of TechnologyCambridgeMAUSA

Phase recovery(PR)refers to calculating the phase of the light field from its intensity *** exemplified from quantitative phase imaging and coherent diffraction imaging to adaptive optics,PR is essential for reconstructing the refractive index distribution or topography of an object and correcting the aberration of an imaging *** recent years,deep learning(DL),often implemented through deep neural networks,has provided unprecedented support for computational imaging,leading to more efficient solutions for various PR *** this review,we first briefly introduce conventional methods for ***,we review how DL provides support for PR from the following three stages,namely,pre-processing,in-processing,and *** also review how DL is used in phase image ***,we summarize the work in DL for PR and provide an outlook on how to better use DL to improve the reliability and efficiency of ***,we present a live-updating resource(https://***/kqwang/phase-recovery)for readers to learn more about PR.

关键词： networks phase optics

SWG: an architecture for sparse weight gradient computation

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Science China(Information Sciences) 2024年第2期67卷 302-321页

作者： Weiwei WU Fengbin TU Xiangyu LI Shaojun WEI Shouyi YIN School of Integrated Circuits Tsinghua University department of electronic and Computer Engineering The Hong Kong University of Science and Technology

On-device training for deep neural networks(DNN) has become a trend due to various user preferences and scenarios. The DNN training process consists of three phases, feedforward(FF), backpropagation(BP), and weight gradient(WG) update. WG takes about one-third of the computation in the whole training process. Current training accelerators usually ignore the special computation property of WG and process it in a way similar to FF/BP. Besides, the extensive data sparsity existing in WG, which brings opportunities to save computation, is not well explored. Nevertheless, exploiting the optimization opportunities would meet three underutilization problems, which are caused by(1) the mismatch between WG data dimensions and hardware parallelism,(2) the full sparsity, i.e., the sparsity of feature map(Fmap),error map(Emap), and gradient, and(3) the workload imbalance resulting from irregular sparsity. In this paper, we propose a specific architecture for sparse weight gradient(SWG) computation. The architecture is designed based on hierarchical unrolling and sparsity-aware(HUSA) dataflow to exploit the optimization opportunities of the special computation property and full data sparsity. In HUSA dataflow, the data dimensions are unrolled hierarchically on the hardware architecture. A valid-data trace(VDT) mechanism is embedded in the dataflow to avoid the underutilization caused by the two-sided input sparsity. The gradient is unrolled in PE to alleviate the underutilization induced by output sparsity while maintaining the data reuse opportunities. Besides, we design an intra-and inter-column balancer(IIBLC) to dynamically tackle the workload imbalance problem resulting from the irregular sparsity. Experimental results show that with HUSA dataflow exploiting the full sparsity, SWG achieves a speedup of 12.23× over state-of-the-art gradient computation architecture, Train Ware. SWG helps to improve the energy efficiency of the state-of-the-art training accelerator LNPU from

关键词： CNN training gradient computation sparsity architecture

Rapid surface texturing to achieve robust superhydrophobicity,controllable droplet impact,and anti-frosting performances

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Friction 2024年第2期12卷 291-304页

作者： Qingwen DAI Lei CHEN Jiabao PAN Liping SHI Dameng LIU Wei HUANG Xiaolei WANG College of mechanical and Electrical Engineering Nanjing University of Aeronautics&AstronauticsNanjing 210016China State Key Laboratory of Tribology in Advanced Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China School of mechanical Engineering Anhui Polytechnic UniversityWuhu 241000China School of mechanical Engineering Anhui University of TechnologyMa’anshan 243032China

Robust superhydrophobic surfaces with excellent capacities of repelling water and anti-frosting are of importance for many mechanical *** this work,wear-resistant superhydrophobic surfaces were fabricated by curing a mixture of polyurethane acrylate(PUA)coating and 1H,1H,2H,2H-Perfluorodecyltrichlorosilane(HFTCS)on titanium alloy(TC4)surfaces decorated with micropillars pattern,thus,composite functional surfaces with PUA coating in the valleys around the micropillars pattern of TC4 were *** contact angle on fabricated surfaces could reach 167°.Influences of the geometric parameters of micropillars pattern on the apparent contact angle were investigated,and the corresponding wear-resistant property was *** impact and anti-frosting performances on the prepared surfaces were *** optimized design of surface texture with robust superhydrophobicity,controllable droplet impact,and anti-frosting performances was *** design principle is of promising prospects for fabricating superhydrophobic surfaces in traditional mechanical systems.

关键词： surface texture robust superhydrophobic wear-resistant droplet impact anti-frosting

Regularizing fuel-optimal multi-impulse trajectories

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Astrodynamics 2024年第1期8卷 97-119页

作者： Kenta Oshima department of mechanical Systems Engineering Hiroshima Institute of TechnologyHiroshima731-5193Japan

The regularization theory has successfully enabled the removal of gravitational singularities associated with celestial *** this study,regularizing techniques are merged into a multi-impulse trajectory design framework that requires delicate computations,particularly for a fuel minimization *** variables based on the Levi–Civita or Kustaanheimo–Stiefel transformations express instantaneous velocity changes in a gradient-based direct optimization *** formulation removes the adverse singularities associated with the null thrust impulses from the derivatives of an objective function in the fuel minimization *** favorite singularity-free property enables the accurate reduction of unnecessary impulses and the generation of necessary impulses for local optimal solutions in an automatic *** of fuel-optimal multi-impulse trajectories are presented,including novel transfer solutions between a near-rectilinear halo orbit and a distant retrograde orbit.

关键词： regularization trajectory optimization fuel minimization multi-impulse trajectory

Advanced Thermochemical Conversion Approaches for Green Hydrogen Production from Crop Residues

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Journal of Renewable Materials 2024年第1期12卷 1-28页

作者： Omojola Awogbemi Ayotunde Adigun Ojo Samson Adedayo Adeleye department of mechanical Engineering Ekiti State UniversityAdo EkitiNigeria

The huge volumes of crop residues generated during the production,processing,and consumption of farm products constitute an ecological nuisance when ineffectively *** conversion of crop residues to green hydrogen is one of the sustainable management strategies for ubiquitous crop *** of green hydrogen from crop residue sources will contribute to deepening access to clean and affordable energy,mitigating climate change,and ensuring environmental ***,the deployment of conventional thermochemical technologies for the conversion of crop residues to green hydrogen is costly,requires long residence time,produces low-quality products,and therefore needs to be *** current review examines the conventional,advanced,and integrated thermochemical conversion technologies for crop residues for green hydrogen *** a brief overview of the conventional thermochemical techniques,the review delves into the broad narration of advanced thermochemical technologies including catalytic pyrolysis,microwave pyrolysis,co-pyrolysis,hyropyrolysis,and autothermal *** study advocates the deployment of integrated pyrolysis,anaerobic digestion,pyrolysis,and gasification technologies will ensure scalability,decomposition of recalcitrant feedstocks,and generation of high grade green *** outlook provides suggestions for future research into cost-saving and sustainable integrated technologies for green hydrogen production towards achieving carbon neutrality and a circular bio-economy.

关键词： Crop residues carbon neutrality pyrolysis gasification green hydrogen thermochemical conversion

Role of magnetic fields on the outer crust in a magnetar

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Chinese Physics C 2024年第7期48卷 160-167页

作者：蒋威陈晏军 department of Physics and electronic Science Changsha University of Science and TechnologyChangsha 410114China Hunan Provincial Key Laboratory of Flexible electronic Materials Genome Engineering Changsha 410114China

We explore the properties of 4110 nuclides from Z=5 to Z=82 with the Sky3D code and the composition of the outer crust in magnetars under extreme magnetic *** effects of the variation in nuclear masses due to magnetic fields on the outer crust are comprehensively *** neutron-drip transition pressure,equation of state,and neutron fraction in the outer crust are also discussed.

关键词： outer crust in a magnetar magnetic fields nuclear masses Sky3D code