检索结果-南通市图书馆

A survey on model-based reinforcement learning

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第2期67卷 59-84页

作者： Fan-ming LUO Tian XU Hang lai Xiong-Hui CHEN Weinan zhang Yang YU National Key Laboratory for Novel Software Technology Nanjing University Polixir. ai Department of Computer Science and Engineering Shanghai Jiao Tong University

Reinforcement learning(RL) interacts with the environment to solve sequential decision-making problems via a trial-and-error approach. Errors are always undesirable in real-world applications, even though RL excels at playing complex video games that permit several trial-and-error attempts. To improve sample efficiency and thus reduce errors, model-based reinforcement learning(MBRL) is believed to be a promising direction, as it constructs environment models in which trial-and-errors can occur without incurring actual costs. In this survey, we investigate MBRL with a particular focus on the recent advancements in deep RL. There is a generalization error between the learned model of a non-tabular environment and the actual environment. Consequently, it is crucial to analyze the disparity between policy training in the environment model and that in the actual environment, guiding algorithm design for improved model learning, model utilization, and policy training. In addition, we discuss the recent developments of model-based techniques in other forms of RL, such as offline RL, goal-conditioned RL, multi-agent RL, and meta-RL. Furthermore,we discuss the applicability and benefits of MBRL for real-world tasks. Finally, this survey concludes with a discussion of the promising future development prospects for MBRL. We believe that MBRL has great unrealized potential and benefits in real-world applications, and we hope this survey will encourage additional research on MBRL.

关键词： reinforcement learning model-based reinforcement learning planning model learning model learning with reduced error model usage

Preface to the Special Issue:Additive Manufacturing—Expanding Production Horizon

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 1-2页

作者： lai-Chang zhang Centre for Advanced Materials and Manufacturing School of EngineeringEdith Cowan University270 Joondalup DriveJoondalupPerthWA6027Australia

Additive manufacturing(AM),commonly known as 3D printing,has become a transformative technology that has a profound impact on various industrial *** encompasses a set of techniques for building objects layer by layer from digital *** conventional subtractive manufacturing methods that involve removing material from large blocks,AM adds material incrementally,providing unprecedented design flexibility and efficiency.

关键词： removing printing Expanding

Mechanical Performance of Bio-inspired Bidirectional Corrugated Sandwich Pressure Shell Under External Hydrostatic Pressure

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Ocean Engineering 2024年第2期38卷 297-312页

作者： zhang Yi CHEN Yue YUN lai LIANG Xu Ocean College Zhejiang UniversityZhoushan 316000China Hainan Institute Zhejiang UniversitySanya 572000China

This paper aims to enhance the compression capacity of underwater cylindrical shells by adopting the corrugated sandwich structure of *** cuttlebone suffers uniaxial external compression,while underwater cylindrical shells are in a biaxial compressive stress *** suit the biaxial compressive stress state,a novel bidirectional corrugated sandwich structure is proposed to improve the bearing capacity of cylindrical *** static and buckling analysis for the sandwich shell and the unstiffened cylindrical shell with the same volume-weight ratio are studied by numerical *** is indicated that the proposed sandwich shell can effectively reduce the ratio between circumferential and axial stress from 2 to 1.25 and improve the critical buckling load by about 1.63 *** simulation shows that optimizing and adjusting the structural parameters could significantly improve the advantage of the sandwich ***,the hydrostatic pressure tests for shell models fabricated by 3D printing are carried *** to the experimental results,the overall failure position of the sandwich shell is at the center part of the sandwich *** has been found the average critical load of the proposed sandwich shell models exceeds two times that of the unstiffened shell ***,the proposed bio-inspired bidirectional corrugated sandwich structure can significantly enhance the pressure resistance capability of cylindrical shells.

关键词： bio-inspiration bidirectional corrugation sandwich shell external pressure buckling

Laser Powder Bed Fusion of Beta-Type Titanium Alloys for Biomedical Application:A Review

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 17-28页

作者： Xuan Luo Chao Yang Dongdong Li lai-Chang zhang State Key Laboratory of Materials Processing and Die&Mould Technology Huazhong University of Science and TechnologyWuhan430074China National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials Guangdong Provincial Key Laboratory for Processing and Forming of Advanced Metallic MaterialsSouth China University of TechnologyGuangzhou510640China Centre for Advanced Materials and Manufacturing School of EngineeringEdith Cowan University270 Joondalup DriveJoondalupPerthWA6027Australia

Additive manufacturing ofβ-type titanium alloy is expected to replace Ti-6Al-4V alloy in the field of orthopedic implantation because of their low elastic modulus,excellent corrosion resistance,and *** briefly introducing the laser powder bed fusion(LPBF)process and physical phenomena,this paper reviews the recent progresses in LPBF-edβ-type Ti *** strategies to strengthening and tougheningβ-type Ti alloys are critically *** is followed by the processing routes employed to achieve to low modulus for orthopedic applications,especially a new methodology for tailoring crystallographic orientation called multi-track coupled directional *** effect of processing and compositions on performance metrics ofβ-type Ti alloys included corrosion behavior,and biocompatibility is *** the end,challenges in additive manufacturing ofβ-type Ti alloys in future are highlighted,with the aim to ensue clinical application of LPBF-edβ-type Ti alloys.

关键词： β-type Ti alloys Laser powder bed fusion Mechanical properties Elastic modulus Biocompatibility

An Improved Thermal Conductivity Measurement Scheme for Macroscopic Graphitic Films Using the Laser Flash Method

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Thermal Science 2024年第4期33卷 1480-1490页

作者： zhang Peijuan ming Xin LIU Yingjun WANG Xuelong SHI Hang HAO Yuanyuan LU Jiahao LIU Zheng lai Haiwen zhang Ying GAO Weiwei XU Zhen GAO Chao MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringKey Laboratory of Adsorption and Separation Materials&Technologies of Zhejiang ProvinceZhejiang UniversityHangzhou310027China Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering Taiyuan030032China Special Equipment Safety Supervision and Inspection Institute of Jiangsu Province National Graphene Products Quality Inspection and Testing Center(Jiangsu)Wuxi214174China Hangzhou Gaoxi Technol Co. LtdHangzhou311113China China Academy of Aerospace Aerodynamics Beijing100074China

Achieving efficient thermal management urges to exploit high-thermal-conductivity materials to satisfy the boosted demand of heat *** is critical to adopt standardized characterization protocols to evaluate the intrinsic thermal conductivity of thermal management ***,for the most representative laser flash method,the lack of standard measurement methodology and systematic description on the thermal diffusivity and influencing factors has led to significant deviations and confusion of the thermal conduction performance in the emerging thermal management ***,the measurement error factors of thermal diffusivity by the common laser flash analyzer(LFA)are *** high-thermal-conductivity graphitic film(GF)as a typical case,the key factors are analyzed to guide the measurement protocol of related carbon-based thermal management *** basic principle of the LFA measurement,actual pre-processing conditions,instrument parameters setting,and data analysis are elaborated for accurate ***,the graphene thick films and common isotropic materials are also extended to meet various thermal measurement *** on the existing practical problems,we propose a feasible test flow to achieve a unified and standardized thermal conductivity measurement,which is beneficial to the rapid development of carbon-based thermal management materials.

关键词： thermal management graphitic film laser flash method thermal conductivity thermal diffusivity

Non-uniform thermal behavior of single-layer spherical reticulated shell structures considering time-variant environmental factors: analysis and design

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第3期25卷 223-237页

作者： Wucheng XU Xiaoqing ZHENG Xuanhe zhang Zhejie lai Yanbin SHEN College of Civil Engineering and Architecture Zhejiang UniversityHangzhou 310058China Center for Balance Architecture Zhejiang UniversityHangzhou 310028China Innovation Center of Yangtze River Delta Zhejiang UniversityJiaxing 314100China Zhejiang Provincial Key Laboratory of Space Structures Zhejiang UniversityHangzhou 310058China

Contrary to conventional design methods that assume uniform and slow temperature changes tied to atmospheric conditions,single-layer spherical reticulated shells undergo significant non-uniform and time-variant temperature variations due to dynamic environmental *** differences can affect structural performance and pose safety ***,a systematic numerical method was developed and applied to simulate long-term temperature variations in such a structure under real environmental conditions,revealing its non-uniform distribution characteristics and time-variant regularity.A simplified design method for non-uniform thermal loads,accounting for time-variant environmental factors,was theoretically derived and validated through experiments and *** maximum deviation and mean error rate between calculated and tested results were 6.1℃ and 3.7%,*** temperature fields aligned with simulated ones,with deviations under 6.0℃.Using the design method,non-uniform thermal effects of the structure are *** member stress and nodal displacement under non-uniform thermal loads reached 119.3 MPa and 19.7 mm,representing increases of 167.5%and 169.9%,respectively,compared to uniform thermal *** impacts of healing construction time on non-uniform thermal effects were evaluated,resulting in construction *** methodologies and conclusions presented here can serve as valuable references for the thermal design,construction,and control of single-layer spherical reticulated shells or similar structures.

关键词： Non-uniform temperature field Non-uniform thermal load Non-uniform thermal effect Single-layer spherical reticulated shell Time-variant environmental factor

Recent innovations in laser additive manufacturing of titanium alloys

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Extreme Manufacturing 2024年第3期6卷 2-37页

作者： Jinlong Su Fulin Jiang Jie Teng Lequn Chen ming Yan Guillermo Requena lai-Chang zhang Y Morris Wang Ilya V Okulov Hongmei Zhu Chaolin Tan College of Materials Science and Engineering Hunan UniversityChangsha 410082People’s Republic of China Singapore Institute of Manufacturing Technology(SIM Tech) Agency for ScienceTechnology and Research(A∗STAR)5 Cleantech LoopSingapore 636732Singapore Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhen 518055People’s Republic of China Institute of Materials Research German Aerospace Center(DLR)Linder Höhe51147 CologneGermany Centre for Advanced Materials and Manufacturing Edith Cowan University270 Joondalup DriveJoondalupPerthWestern Australia 6027Australia Department of Materials Science and Engineering University of CaliforniaLos AngelesCA 900095United States of America Leibniz Institute for Materials Engineering-IWT Badgasteiner Str.328359 BremenGermany Faculty of Production Engineering University of BremenBadgasteiner Str.128359 BremenGermany Key Laboratory of Hunan Province of Equipment Safety Service Technology under Extreme Environment University of South ChinaHengyangPeople’s Republic of China RWTH Aachen University Metallic Structures and Materials Systems for Aerospace EngineeringD-52062 AachenGermany

Titanium(Ti)alloys are widely used in high-tech fields like aerospace and biomedical *** additive manufacturing(LAM),as an innovative technology,is the key driver for the development of Ti *** the significant advancements in LAM of Ti alloys,there remain challenges that need further research and development *** recap the potential of LAM high-performance Ti alloy,this article systematically reviews LAM Ti alloys with up-to-date information on process,materials,and *** feasible solutions to advance LAM Ti alloys are reviewed,including intelligent process parameters optimization,LAM process innovation with auxiliary fields and novel Ti alloys customization for *** auxiliary energy fields(***,acoustic,mechanical deformation and magnetic fields)can affect the melt pool dynamics and solidification behaviour during LAM of Ti alloys,altering microstructures and mechanical *** kinds of novel Ti alloys customized for LAM,like peritecticα-Ti,eutectoid(α+β)-Ti,hybrid(α+β)-Ti,isomorphousβ-Ti and eutecticβ-Ti alloys are reviewed in ***,machine learning in accelerating the LAM process optimization and new materials development is also *** review summarizes the material properties and performance envelops and benchmarks the research achievements in LAM of Ti *** addition,the perspectives and further trends in LAM of Ti alloys are also highlighted.

关键词： additive manufacturing titanium alloys auxiliary field machine learning aerospace materials lightweight materials novel alloys

Lacticaseibacillus rhamnosus Probio-M9 may be vertically transmitted from mother to infant during lactation based on faeces metagenomics

在线全文

学校读者我要写书评

暂无评论

Food Science and Human Wellness 2024年第2期13卷 721-728页

作者： Lan Yang lai-Yu Kwok Zhihong Sun Heping zhang Key Laboratory of Dairy Biotechnology and Engineering Ministry of EducationInner Mongolia Agricultural UniversityHohhot 010018China Key Laboratory of Dairy Products Processing Ministry of Agriculture and Rural AffairsInner Mongolia Agricultural UniversityHohhot 010018China Inner Mongolia Key Laboratory of Dairy Biotechnology and Engineering Inner Mongolia Agricultural UniversityHohhot 010018China

Probiotics exert beneficial effects on the *** study aimed to investigate whether maternally ingested Lacticaseibacillus rhamnosus Probio-M9 during pregnancy could access and colonize the infant *** study recruited one pregnant woman,who ingested Probio-M9 daily from 35 weeks of gestation to *** of the mother-infant pair were regularly collected from one month before delivery to 6 months of infant's age for metagenomic ***-M9 genomes were mappable to all infant fecal samples,suggesting the ingested probiotics could be vertically transmitted from mother to ***-or mother-specific differential metabolic pathways were found between the maternal and infant's gut microbiome,implicating apparent differences in the intestinal metagenomic potential/function between the mother and the *** conclusion,maternal ingestion of Probio-M9 during the final weeks of gestation could deliver to the infant *** findings provided novel insights into shaping infant's gut microbiota.

关键词： Metagenomic analysis Lacticaseibacillus rhamnosus Gut microbiome Mother Infant

Adrenal pheochromocytoma impacts three main pathways: cysteine-methionine, pyrimidine, and tyrosine metabolism

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2024年第5期25卷 410-421页

作者： Chong lai Qingling YANG Yunuo zhang Renjie GONG Majie WANG Jiankang LI Maode lai Qingrong SUN Department of Urology the First Affiliated HospitalZhejiang University School of MedicineHangzhou 310003China School of Basic Medical Sciences and Clinical Pharmacy China Pharmaceutical UniversityNanjing 210009China Department of Laboratory Medicine the First Affiliated HospitalZhejiang University School of MedicineHangzhou 310003China Laboratory of Behavioral Neuroscience Ningbo Kangning HospitalNingbo Institute of Microcirculation and HenbaneSchool of MedicineNingbo UniversityNingbo 315201China Xi'an Key Laboratory of Stem Celland Regenerative Medicine Institute of Medical ResearchNorthwestern Polytechnical UniversityXi'an 710072China Department of Pathology Research Unit of Intelligence Classification of Tumor Pathology and Precision TherapyChinese Academy of Medical Sciences Key Laboratory of Disease Proteomics of Zhejiang ProvinceZhejiang University School of MedicineHangzhou 310058China

Pheochromocytomas and paragangliomas(PPGLs)cause symptoms by altering the circulation levels of catecholamines and peptide ***,the diagnosis of PPGLs relies on diagnostic imaging and the detection of *** this study,we used ultra-performance liquid chromatography(UPLC)/quadrupole time-of-flight mass spectrometry(Q-TOF MS)analysis to identify and measure the perioperative differential metabolites in the plasma of adrenal pheochromocytoma *** identified differentially expressed genes by comparing the transcriptomic data of pheochromocytoma with the normal adrenal *** conducting two steps of metabolomics analysis,we identified 111 differential metabolites between the healthy group and the patient group,among which 53 metabolites were *** integrating the information of differential metabolites and differentially expressed genes,we inferred that the cysteine-methionine,pyrimidine,and tyrosine metabolism pathways were the three main metabolic pathways altered by the *** analysis of transcription levels revealed that the tyrosine and cysteine-methionine metabolism pathways were downregulated in pheochromocytoma,whereas the pyrimidine pathway showed no significant ***,we developed an optimized diagnostic model of two metabolites,L-dihydroorotic acid and *** results for these metabolites suggest that they may serve as potential clinical biomarkers and can be used to supplement and improve the diagnosis of pheochromocytoma.

关键词： Pheochromocytoma and paraganglioma(PPGL) Metabolomics Gene set variation analysis L-Dihydroorotic acid Vanylglycol