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Development of lunar regolith composite and structure via laser-assisted sintering

《机械工程前沿(英文)》 doi: 10.1007/s11465-021-0662-2

摘要: Aiming at the exploration and resource utilization activities on the Moon, in situ resource utilization and in situ manufacturing are proposed to minimize the dependence on the ground transportation supplies. In this paper, a laser-assisted additive manufacturing process is developed to fabricate lunar regolith composites with PA12/SiO2 mixing powders. The process parameters and composite material compositions are optimized in an appropriate range through orthogonal experiments to establish the relationship of process–structure–property for lunar regolith composites. The optimal combination of composite material compositions and process parameters are mixing ratio of 50/50 in volume, laser power of 30 W, scanning speed of 3500 mm/s, and scanning hatch space of 0.2 mm. The maximum tensile strength of lunar regolith composites reaches 9.248 MPa, and the maximum depth of surface variation is 120.79 μm, which indicates poor powder fusion and sintering quality. Thereafter, the mechanical properties of laser-sintered lunar regolith composites are implemented to the topology optimization design of complex structures. The effectiveness and the feasibility of this laser-assisted process are potentially developed for future lightweight design and manufacturing of the solar panel installed on the lunar rover.

关键词: in situ manufacturing     laser-assisted powder fusion process     mechanical properties     topological structure design    

Conceptual design of compliant mechanisms using level set method

Shi-kui CHEN, Michael Yu WANG

《机械工程前沿(英文)》 2006年 第1卷 第2期   页码 131-145 doi: 10.1007/s11465-006-0018-y

摘要: We propose a level set method-based framework for the conceptual design of compliant mechanisms. In this method, the compliant mechanism design problem is recast as an infinite dimensional optimization problem, where the design variable is the geometric shape of the compliant mechanism and the goal is to find a suitable shape in the admissible design space so that the objective functional can reach a minimum. The geometric shape of the compliant mechanism is represented as the zero level set of a one-higher dimensional level set function, and the dynamic variations of the shape are governed by the Hamilton-Jacobi partial differential equation. The application of level set methods endows the optimization process with the particular quality that topological changes of the boundary, such as merging or splitting, can be handled in a natural fashion. By making a connection between the velocity field in the Hamilton-Jacobi partial differential equation with the shape gradient of the objective functional, we go further to transform the optimization problem into that of finding a steady-state solution of the partial differential equation. Besides the above-mentioned methodological issues, some numerical examples together with prototypes are presented to validate the performance of the method.

关键词: splitting     minimum     dimensional optimization     Hamilton-Jacobi     topological    

Mortarless structures based on topological interlocking

Arcady V. DYSKIN, Elena PASTERNAK, Yuri ESTRIN

《结构与土木工程前沿(英文)》 2012年 第6卷 第2期   页码 188-197 doi: 10.1007/s11709-012-0156-8

摘要: We review the principle of topological interlocking and analyze the properties of the mortarless structures whose design is based on this principle. We concentrate on structures built of osteomorphic blocks – the blocks possessing specially engineered contact surfaces allowing assembling various 2D and 3D structures. These structures are easy to build and can be made demountable. They are flexible, resistant to macroscopic fractures and tolerant to missing blocks. The blocks are kept in place without keys or connectors that are the weakest elements of the conventional interlocking structures. The overall structural integrity of these structures depends on the force imposed by peripheral constraint. The peripheral constraint can be provided in various ways: by an external frame or features of site topography, internal pre-stressed cables/tendons, or self-weight and is a necessary auxiliary element of the structure. The constraining force also determines the degree of delamination developing between the blocks due to bending and thus controls the overall flexibility of the structure thus becoming a new design parameter.

关键词: topological interlocking     fragmented structures     segmented structures     constraint     delamination     bending stiffness    

Lightweight design of an electric bus body structure with analytical target cascading

《机械工程前沿(英文)》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0718-y

摘要: Lightweight designs of new-energy vehicles can reduce energy consumption, thereby improving driving mileage. In this study, a lightweight design of a newly developed multi-material electric bus body structure is examined in combination with analytical target cascading (ATC). By proposing an ATC-based two-level optimization strategy, the original lightweight design problem is decomposed into the system level and three subsystem levels. The system-level optimization model is related to mass minimization with all the structural modal frequency constraints, while each subsystem-level optimization model is related to the sub-structural performance objective with sub-structure mass constraints. To enhance the interaction between two-level systems, each subsystem-level objective is reformulated as a penalty-based function coordinated with the system-level objective. To guarantee the accuracy of the model-based analysis, a finite element model is validated through experimental modal test. A sequential quadratic programming algorithm is used to address the defined optimization problem for effective convergence. Compared with the initial design, the total mass is reduced by 49 kg, and the torsional stiffness is increased by 17.5%. In addition, the obtained design is also validated through strength analysis.

关键词: electric vehicle     body in white (BIW)     lightweight     analytical target cascading (ATC)    

三维体目标间拓扑方向关系描述和推理

刘新,李成名,刘文宝

《中国工程科学》 2013年 第15卷 第5期   页码 8-13

摘要:

空间关系描述了地理信息系统(GIS)中实体间的位置、距离、方位、拓扑等的度量。为提高空间关系描述的惟一性和空间关系推理的准确性,将拓扑关系与方向关系集成描述,构建拓扑方向关系的描述表达模型。目标对象与参照物在X、Y、Z 3个坐标轴上投影间的Allen区间关系分别为[R1]、[R2]和[R3],提出利用Allen区间关系对[(R1,R2,R3)]描述三维拓扑方向区域,用定义法研究拓扑方向关系定性推理,通过一些典型例子说明拓扑方向关系推理过程和结果,推理结果用组合推理表表示。

关键词: 空间关系     拓扑关系     方向关系     拓扑方向关系     三维空间    

Application of a vertex chain operation algorithm on topological analysis of three-dimensional fractured

Zixin ZHANG, Jia WU, Xin HUANG

《结构与土木工程前沿(英文)》 2017年 第11卷 第2期   页码 187-208 doi: 10.1007/s11709-017-0391-0

摘要: Identifying the morphology of rock blocks is vital to accurate modelling of rock mass structures. This paper applies the concepts of directed edges and vertex chain operations which are typical for block tracing approach to block assembling approach to construct the structure of three-dimensional fractured rock masses. Polygon subtraction and union algorithms that rely merely on vertex chain operation are proposed, which allow a fast and convenient construction of complex faces/loops. Apart from its robustness in dealing with finite discontinuities and complex geometries, the advantages of the current methodology in tackling some challenging issues associated with the morphological analysis of rock blocks are addressed. In particular, the identification of complex blocks with interior voids such as cavity, pit and torus can be readily achieved based on the number and the type of loops. The improved morphology visualization approach can benefit the pre-processing stage when analyzing the stability of rock masses subject to various engineering impacts using the block theory and the discrete element method.

关键词: morphology     block assembling     vertex operation     discontinuities    

Design and applications of morphing aircraft and their structures

《机械工程前沿(英文)》 2023年 第18卷 第3期 doi: 10.1007/s11465-023-0750-6

摘要: Morphing aircraft can adaptively regulate their aerodynamic layout to meet the demands of varying flight conditions, improve their aerodynamic efficiency, and reduce their energy consumption. The design and fabrication of high-performance, lightweight, and intelligent morphing structures have become a hot topic in advanced aircraft design. This paper discusses morphing aircraft development history, structural characteristics, existing applications, and future prospects. First, some conventional mechanical morphing aircraft are examined with focus on their morphing modes, mechanisms, advantages, and disadvantages. Second, the novel applications of several technologies for morphing unmanned aerial vehicles, including additive manufacturing for fabricating complex morphing structures, lattice technology for reducing structural weight, and multi-mode morphing combined with flexible skins and foldable structures, are summarized and categorized. Moreover, in consideration of the further development of active morphing aircraft, the paper reviews morphing structures driven by smart material actuators, such as shape memory alloy and macro-fiber composites, and analyzes their advantages and limitations. Third, the paper discusses multiple challenges, including flexible structures, flexible skins, and control systems, in the design of future morphing aircraft. Lastly, the development and application of morphing structures in the aerospace field are discussed to provide a reference for future research and engineering applications.

关键词: morphing aircraft     additive manufacturing     lattice structure     smart material     flexible structure     flexible skin    

“Charging” the cigarette butt: heteroatomic porous carbon nanosheets with edge-induced topological defects

《化学科学与工程前沿(英文)》 2023年 第17卷 第11期   页码 1755-1764 doi: 10.1007/s11705-023-2318-8

摘要: Owing to the complexity of electron transfer pathways, the sluggish oxygen evolution reaction process is defined as the bottleneck for the practical application of Zn–air batteries. In this effort, metal nanoparticles (Co, Ni, Fe, etc.) encapsulated within nitrogen-doped carbon materials with abundant edge sites were synthesized by one-step pyrolysis treatment using cigarette butts as raw materials, which can drastically accelerate the overall rate of oxygen evolution reaction by facilitating the adsorption of oxygenated intermediates by the edge-induced topological defects. The prepared catalyst of nitrogen-doped carbon porous nanosheets loaded with Co nanoparticles (Co@NC-500) exhibits enhanced catalytic activity toward oxygen evolution reaction, with a low overpotential of 350 mV at the current density of 10 mA·cm–2. Furthermore, the Zn–air battery assembled with Co@NC-500 catalyst demonstrates a desirable performance affording an open-circuit potential of 1.336 V and power density of 33.6 mW·cm–2, indicating considerable practical application potential.

关键词: oxygen evolution reaction     porous carbon nanosheets     Co nanoparticles     edge-induced topological defects     Zn–air batteries    

Virtual network embedding based on real-time topological attributes

Jian DING,Tao HUANG,Jiang LIU,Yun-jie LIU

《信息与电子工程前沿(英文)》 2015年 第16卷 第2期   页码 109-118 doi: 10.1631/FITEE.1400147

摘要: As a great challenge of network virtualization, virtual network embedding/mapping is increasingly important. It aims to successfully and efficiently assign the nodes and links of a virtual network (VN) onto a shared substrate network. The problem has been proved to be NP-hard and some heuristic algorithms have been proposed. However, most of the algorithms use only the local information of a node, such as CPU capacity and bandwidth, to determine how to map a VN, without considering the topological attributes which may pose significant impact on the performance of the embedding. In this paper, a new embedding algorithm is proposed based on real-time topological attributes. The concept of betweenness centrality in graph theory is borrowed to sort the nodes of VNs, and the nodes of the substrate network are sorted according to the correlation properties between the former selected and unselected nodes. In this way, node mapping and link mapping can be well coupled. A simulator is built to evaluate the performance of the proposed virtual network embedding (VNE) algorithm. The results show that the new algorithm significantly increases the revenue/cost (R/C) ratio and acceptance ratio as well as reduces the runtime.

关键词: Virtual network embedding (VNE)     Real-time topological attributes     Betweenness centrality     Correlation properties     Network virtualization    

拓扑关系与性质及其在空间推理中的应用

李成名,刘晓丽

《中国工程科学》 2013年 第15卷 第5期   页码 14-19

摘要:

首先根据笔者以前的研究成果,给出了两个空间实体之间完备、唯一的拓扑关系形式化表达,进而论述了它们之间存在的性质。从这些性质出发,得出了相互间空间关系复合的结果。空间推理从广义上而言,是指从已知信息推导未知信息的理论和方法,据其使用的理论基础,可以分为代数推理和逻辑推理,空间复合的结果可以直接用于代数推理,又可以作为前提条件用于逻辑推理。

关键词: 拓扑关系     空间关系复合     空间推理     代数推理     逻辑推理    

Optimal dome design considering member-related design constraints

Tugrul TALASLIOGLU

《结构与土木工程前沿(英文)》 2019年 第13卷 第5期   页码 1150-1170 doi: 10.1007/s11709-019-0543-5

摘要: This study proposes to optimize the design of geometrically nonlinear dome structures. A new Multi-objective Optimization Algorithm named Pareto Archived Genetic Algorithm (PAGA), which has an ability of integrating the nonlinear structural analysis with the provisions of American Petroleum Institute specification is employed to optimize the design of ellipse and sphere-shaped dome configurations. Thus, it is possible to investigate how the qualities of optimal designations vary considering the shape, size, and topology-related design variables. Furthermore, the computing efficiency of PAGA is evaluated considering six multi-objective optimization algorithms and eight quality measuring indicators. It is shown that PAGA has a capability of both exploring an increased number of pareto solutions and predicting a pareto front with a higher convergence degree. Moreover, the inclusion of shape-related design variables leads to a decrease in both the weights of dome structures and their load-carrying capacities. However, the designer easily determines the most requested optimal design through the archiving feature of PAGA. Thus, it is also demonstrated that the proposed optimal design procedure increases the correctness degree in the evaluation of optimal dome designs through the tradeoff analysis. Consequently, PAGA is recommended as an optimization tool for the design optimization of geometrically nonlinear dome structures.

关键词: dome structure     geometric nonlinearity     multi-objective optimization     API RP2A-LRFD    

关于浮选药剂的梦想 ——浮选药剂结构-性能关系和分子设计

王淀佐,姚国成

《中国工程科学》 2011年 第13卷 第3期   页码 4-11

摘要:

泡沫浮选技术从20世纪初开始规模工业应用,是矿产资源高效利用的重要手段。浮选药剂是这一技术的科学基础和关键。文章介绍并讨论了浮选药剂的结构-性能定量关系及药剂分子设计的研究历程和新进展。

关键词: 选矿     浮选药剂     结构性能     分子设计    

Topological reorganization and functional alteration of distinct genomic components in gallbladder cancer

《医学前沿(英文)》 doi: 10.1007/s11684-023-1008-8

摘要: Altered three-dimensional architecture of chromatin influences various genomic regulators and subsequent gene expression in human cancer. However, knowledge of the topological rearrangement of genomic hierarchical layers in cancer is largely limited. Here, by taking advantage of in situ Hi-C, RNA-sequencing, and chromatin immunoprecipitation sequencing (ChIP-seq), we investigated structural reorganization and functional changes in chromosomal compartments, topologically associated domains (TADs), and CCCTC binding factor (CTCF)-mediated loops in gallbladder cancer (GBC) tissues and cell lines. We observed that the chromosomal compartment A/B switch was correlated with CTCF binding levels and gene expression changes. Increased inter-TAD interactions with weaker TAD boundaries were identified in cancer cell lines relative to normal controls. Furthermore, the chromatin short loops and cancer unique loops associated with chromatin remodeling and epithelial–mesenchymal transition activation were enriched in cancer compared with their control counterparts. Cancer-specific enhancer–promoter loops, which contain multiple transcription factor binding motifs, acted as a central element to regulate aberrant gene expression. Depletion of individual enhancers in each loop anchor that connects with promoters led to the inhibition of their corresponding gene expressions. Collectively, our data offer the landscape of hierarchical layers of cancer genome and functional alterations that contribute to the development of GBC.

关键词: 3D genome     cancer     TADs     loop     gene regulation    

渤海海峡隧道支护结构形式及参数研究

万飞,王云龙,吴永胜

《中国工程科学》 2013年 第15卷 第12期   页码 61-66

摘要:

借鉴已建成海底隧道的成功经验,采用工程类比法进行渤海海峡隧道支护结构形式及参数设计。通过调研及对比分析,支护结构形式采用复合式衬砌,针对各级围岩初期支护采用相应的支护措施组合方案。隧道主要采用限量排放的防排水系统,衬砌外水压力采用折减系数法计算。在衬砌结构受力分析时,分析了不同水压力下衬砌的安全系数,并初步确定衬砌的设计参数。

关键词: 渤海海峡     海底隧道     结构形式     支护参数    

DISCOVERY OF TRIKETONE-QUINOXALINE HYBRIDS AS POTENT HPPD INHIBITORS USING STRUCTURE-BASED DRUG DESIGN

《农业科学与工程前沿(英文)》 2022年 第9卷 第1期   页码 133-145 doi: 10.15302/J-FASE-2021401

摘要:

p-Hydroxyphenylpyruvate dioxygenase (EC 1.13.11.27, HPPD) belongs to the family of Fe(II)-dependent non-heme oxygenases that occur in the majority of aerobic organisms. HPPD has proved to be a promising target in herbicide research and development. A battery of novel triketone-quinoxaline compounds has been designed using a structure-based drug design strategy and then prepared. Enzyme inhibition assays show that these synthesized derivatives possess favorable inhibition capability against Arabidopsis thaliana HPPD with IC50 values ranging from 0.317 to 0.891 μmol·L1. Subsequently, the molecular docking results indicate that two adjacent carbonyls of the triketone moiety of the representative compound 2-(2,3-dimethyl-8-(o-tolyl)quinoxaline-6-carbonyl)-3-hydroxycyclohex-2-en-1-one (7d) engage in chelation with the ferrous ion of A. thaliana HPPD in a bidentate pose, and its quinoxaline scaffold forms two sets of parallel π-stacking interaction between two phenylalanine residues (Phe424 and Phe381). In addition, the extended phenyl group also interacts with Phe392 in a π-π stacking way. This study indicates that triketone-quinoxaline is a promising scaffold for discovering HPPD inhibitors with substantially increased potency, providing insight into the molecular design of new herbicides.

 

关键词: herbicide / HPPD / inhibitor / quinoxaline / triketon    

标题 作者 时间 类型 操作

Development of lunar regolith composite and structure via laser-assisted sintering

期刊论文

Conceptual design of compliant mechanisms using level set method

Shi-kui CHEN, Michael Yu WANG

期刊论文

Mortarless structures based on topological interlocking

Arcady V. DYSKIN, Elena PASTERNAK, Yuri ESTRIN

期刊论文

Lightweight design of an electric bus body structure with analytical target cascading

期刊论文

三维体目标间拓扑方向关系描述和推理

刘新,李成名,刘文宝

期刊论文

Application of a vertex chain operation algorithm on topological analysis of three-dimensional fractured

Zixin ZHANG, Jia WU, Xin HUANG

期刊论文

Design and applications of morphing aircraft and their structures

期刊论文

“Charging” the cigarette butt: heteroatomic porous carbon nanosheets with edge-induced topological defects

期刊论文

Virtual network embedding based on real-time topological attributes

Jian DING,Tao HUANG,Jiang LIU,Yun-jie LIU

期刊论文

拓扑关系与性质及其在空间推理中的应用

李成名,刘晓丽

期刊论文

Optimal dome design considering member-related design constraints

Tugrul TALASLIOGLU

期刊论文

关于浮选药剂的梦想 ——浮选药剂结构-性能关系和分子设计

王淀佐,姚国成

期刊论文

Topological reorganization and functional alteration of distinct genomic components in gallbladder cancer

期刊论文

渤海海峡隧道支护结构形式及参数研究

万飞,王云龙,吴永胜

期刊论文

DISCOVERY OF TRIKETONE-QUINOXALINE HYBRIDS AS POTENT HPPD INHIBITORS USING STRUCTURE-BASED DRUG DESIGN

期刊论文