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Continuous modeling of soil morphology —thermomechanical behavior of embankment dams

Bettina ALBERS, Krzysztof WILMANSKI

《结构与土木工程前沿(英文)》 2011年 第5卷 第1期   页码 11-23 doi: 10.1007/s11709-010-0081-7

摘要: Macroscopic modeling of soils is based on a number of properties that refer to the mesoscopic morphology. The most fundamental parameters of this art are: 1) coupling parameters between partial stresses of components and deformations of components, 2) porosities, 3) saturation, and 4) permeability and diffusivity, tortuosity. The main aim of this paper is to present in juxtaposition continuous one-, two-, and three-component models of geomaterials appearing in construction of embankment dams. In particular, the above mentioned features, especially saturation with water and seepage problems, modeling of fluidization yielding piping, and generalizations of the Darcy law and changes of porosity, are presented.

关键词: thermomechanical modeling     soil morphology     saturation     porosity    

Flow and thermal modeling of liquid metal in expanded microchannel heat sink

《能源前沿(英文)》   页码 796-810 doi: 10.1007/s11708-023-0877-5

摘要: Liquid metal-based microchannel heat sinks (MCHSs) suffer from the low heat capacity of coolant, resulting in an excessive temperature rise of coolant and heat sink when dealing with high-power heat dissipation. In this paper, it was found that expanded space at the top of fins could distribute the heat inside microchannels, reducing the temperature rise of coolant and heat sink. The orthogonal experiments revealed that expanding the top space of channels yielded similar temperature reductions to changing the channel width. The flow and thermal modeling of expanded microchannel heat sink (E-MCHS) were analyzed by both using the 3-dimensional (3D) numerical simulation and the 1-dimensional (1D) thermal resistance model. The fin efficiency of E-MCHS was derived to improve the accuracy of the 1D thermal resistance model. The heat conduction of liquid metal in Z direction and the heat convection between the top surface of fins and the liquid metal could reduce the total thermal resistance (Rt). The above process was effective for microchannels with low channel aspect ratio, low mean velocity (Um) or long heat sink length. The maximum thermal resistance reduction in the example of this paper reached 36.0%. The expanded space endowed the heat sink with lower pressure, which might further reduce the pumping power (P). This rule was feasible both when fins were truncated (h2 < 0, h2 is the height of expanded channel for E-MCHS) and when over plate was raised (h2 > 0).

关键词: liquid metal cooling     heat sink     expanded microchannel     flow and thermal modeling    

一种集成的统一建模语言框架

Mohammad ALSHAYEB,Nasser KHASHAN,Sajjad MAHMOOD

《信息与电子工程前沿(英文)》 2016年 第17卷 第2期   页码 143-159 doi: 10.1631/FITEE.1500094

摘要:

The unified modeling language (UML) is one of the most commonly used modeling languages in the software industry.It simplifies the complex process of design by providing a set of graphical notations, which helps express the objectoriented analysis and design of software projects. Although UML is applicable to different types of systems, domains, methods,and processes, it cannot express certain problem domain needs. Therefore, many extensions to UML have been proposed. In this paper, we propose a framework for integrating the UML extensions and then use the framework to propose an integrated unified modeling language-graphical (iUML-g) form. iUML-g integrates the existing UML extensions into one integrated form. This includes an integrated diagram for UML class, sequence, and use case diagrams. The proposed approach is evaluated using a case study. The proposed iUML-g is capable of modeling systems that use different domains.

关键词: Unified modeling language (UML)     Integration     Modeling     System analysis and design    

Computer modeling of crystal growth of silicon for solar cells

Lijun LIU, Xin LIU, Zaoyang LI, Koichi KAKIMOTO

《能源前沿(英文)》 2011年 第5卷 第3期   页码 305-312 doi: 10.1007/s11708-011-0155-9

摘要: A computer simulator with a global model of heat transfer during crystal growth of Si for solar cells is developed. The convective, conductive, and radiative heat transfers in the furnace are solved together in a coupled manner using the finite volume method. A three-dimensional (3D) global heat transfer model with 3D features is especially made suitable for any crystal growth, while the requirement for computer resources is kept permissible for engineering applications. A structured/unstructured combined mesh scheme is proposed to improve the efficiency and accuracy of the simulation. A dynamic model for the melt-crystal (mc) interface is developed to predict the phase interface behavior in a crystal growth process. Dynamic models for impurities and precipitates are also incorporated into the simulator. Applications of the computer simulator to Czochralski (CZ) growth processes and directional solidification processes of Si crystals for solar cells are introduced. Some typical results, including the turbulent melt flow in a large-scale crucible of a CZ-Si process, the dynamic behaviors of the mc interface, and the transport and distributions of impurities and precipitates, such as oxygen, carbon, and SiC particles, are presented and discussed. The findings show the importance of computer modeling as an effective tool in the analysis and improvement of crystal growth processes and furnace designs for solar Si material.

关键词: computer modeling     silicon     crystal growth     solar cells    

Lamb wave propagation modeling for structure health monitoring

Xiaoyue ZHANG, Shenfang YUAN, Tong HAO

《机械工程前沿(英文)》 2009年 第4卷 第3期   页码 326-331 doi: 10.1007/s11465-009-0045-6

摘要: This study aims to model the propagation of Lamb waves used in structure health monitoring. A number of different numerical computational techniques have been developed for wave propagation studies. The local interaction simulation approach, used for modeling sharp interfaces and discontinuities in complex media (LISA/SIM theory), has been effectively applied to numerical simulations of elastic wave interaction. This modeling is based on the local interaction simulation approach theory and is finally accomplished through the finite elements software Ansys11. In this paper, the Lamb waves propagating characteristics and the LISA/SIM theory are introduced. The finite difference equations describing wave propagation used in the LISA/SIM theory are obtained. Then, an anisotropic metallic plate model is modeled and a simulating Lamb waves signal is loaded on. Finally, the Lamb waves propagation modeling is implemented.

关键词: Lamb wave     modeling     LISA/SIM theory     finite difference equation     finite element    

Building information modeling and its impact on users in the lifeworld: A mediation perspective

Hans VOORDIJK

《工程管理前沿(英文)》 2019年 第6卷 第2期   页码 193-206 doi: 10.1007/s42524-019-0013-8

摘要: Building information modeling (BIM) is expected to have a large impact on users in the lifeworlds in a construction supply chain. The impact of BIM on users in their lifeworlds is explored using the concepts of Heidegger, Habermas, and Ihde from the perspective of technical mediation. This impact is explored by a case study. BIM mediates and shapes the relationship between users and their lifeworlds and can be characterized as either a hermeneutic or an alterity relationship. BIM conflicts with existing work practices in a ready-to-hand work environment. For users that cannot work with BIM, the work environment remains present-at-hand. The many heterogeneous BIM applications and systems used by the various parties involved result in interoperability problems that are a major barrier to enframing the supply chain by BIM. Although invitation and inhibition of certain actions by BIM may stimulate the rationalization of the lifeworlds, the lack of intrinsic motivation and mutual background knowledge inhibits an alignment of BIM and working practices.

关键词: building information modeling     mediation     enframing     lifeworld     rationalization     Heidegger     Habermas     Ihde    

Integrating storm surge modeling with traffic data analysis to evaluate the effectiveness of hurricane

《结构与土木工程前沿(英文)》 2021年 第15卷 第6期   页码 1301-1316 doi: 10.1007/s11709-021-0765-1

摘要: An integrated storm surge modeling and traffic analysis were conducted in this study to assess the effectiveness of hurricane evacuations through a case study of Hurricane Irma. The Category 5 hurricane in 2017 caused a record evacuation with an estimated 6.8 million people relocating statewide in Florida. The Advanced Circulation (ADCIRC) model was applied to simulate storm tides during the hurricane event. Model validations indicated that simulated pressures, winds, and storm surge compared well with observations. Model simulated storm tides and winds were used to estimate the area affected by Hurricane Irma. Results showed that the storm surge and strong wind mainly affected coastal counties in south-west Florida. Only moderate storm tides (maximum about 2.5 m) and maximum wind speed about 115 mph were shown in both model simulations and Federal Emergency Management Agency (FEMA) post-hurricane assessment near the area of hurricane landfall. Storm surges did not rise to the 100-year flood elevation level. The maximum wind was much below the design wind speed of 150–170 mph (Category 5) as defined in Florida Building Code (FBC) for south Florida coastal areas. Compared with the total population of about 2.25 million in the six coastal counties affected by storm surge and Category 1–3 wind, the statewide evacuation of approximately 6.8 million people was found to be an over-evacuation due mainly to the uncertainty of hurricane path, which shifted from south-east to south-west Florida. The uncertainty of hurricane tracks made it difficult to predict the appropriate storm surge inundation zone for evacuation. Traffic data were used to analyze the evacuation traffic patterns. In south-east Florida, evacuation traffic started 4 days before the hurricane’s arrival. However, the hurricane path shifted and eventually landed in south-west Florida, which caused a high level of evacuation traffic in south-west Florida. Over-evacuation caused Evacuation Traffic Index (ETI) to increase to 200% above normal conditions in some sections of highways, which reduced the effectiveness of evacuation. Results from this study show that evacuation efficiency can be improved in the future by more accurate hurricane forecasting, better public awareness of real-time storm surge and wind as well as integrated storm surge and evacuation modeling for quick response to the uncertainty of hurricane forecasting.

关键词: storm surge modeling     traffic     evacuation     Hurricane Irma    

Hierarchical modeling of stochastic manufacturing and service systems

Zhe George ZHANG, Xiaoling YIN

《工程管理前沿(英文)》 2017年 第4卷 第3期   页码 295-303 doi: 10.15302/J-FEM-2017047

摘要: This paper presents a review of methodologies for analyzing stochastic manufacturing and service systems. On the basis of the scale and level of details of operations, we can study stochastic systems using micro-, meso-, and macro-scopic models. Such a classification unifies stochastic modeling theory. For each model type, we highlight the advantages and disadvantages and the applicable situations. Micro-scopic models are based on quasi-birth-and-death process because of the phase-type distributed service times and/or Markov arrival processes. Such models are appropriate for modeling the detailed operations of a manufacturing system with relatively small number of servers (production facilities). By contrast, meso-scopic and macro-scopic models are based on the functional central limit theorem (FCLT) and functional strong law of large numbers (FSLLN), respectively, under heavy-traffic regimes. These high-level models are appropriate for modeling large-scale service systems with many servers, such as call centers or large service networks. This review will help practitioners select the appropriate level of modeling to enhance their understanding of the dynamic behavior of manufacturing or service systems. Enhanced understanding will ensure that optimal policies can be designed to improve system performance. Researchers in operation analytics and optimization of manufacturing and logistics also benefit from such a review.

关键词: stochastic modeling     QBD process     PH distribution     heavy traffic limits     diffusion process    

Structural modeling of a typical gas turbine system

Naresh YADAV, Irshad Ahmad KHAN, Sandeep GROVER

《能源前沿(英文)》 2012年 第6卷 第1期   页码 57-79 doi: 10.1007/s11708-011-0164-8

摘要: This paper presents an approach for the structural modeling and analysis of a typical gas turbine system. This approach has been applied to the systems and subsystems, which are integral parts of a typical gas turbine system. Since a gas turbine system performance is measured in terms of fluid flow energy transformations across its various assemblies and subassemblies, the performance of such subsystems affects the overall performance of the gas turbine system. An attempt has been made to correlate the associativity of such subsystems contributing to overall gas turbine system functional evaluation using graph theoretic approach. The characteristic equations at the system level as well as subsystem level have been developed on the basis of associativity of various factors affecting their performance. A permanent function has been proposed for the functional model of a gas turbine system, which further leads to selection, identification and optimal evaluation of gas turbine systems.

关键词: system modeling     gas turbine system evaluation     graph theoretic approach    

HOTSPOTS OF NUTRIENT LOSSES TO AIR AND WATER: AN INTEGRATED MODELING APPROACH FOR EUROPEAN RIVER BASINS

《农业科学与工程前沿(英文)》 2023年 第10卷 第4期   页码 579-592 doi: 10.15302/J-FASE-2023526

摘要:

Nutrient pollution of air and water is a persistent problem in Europe. However, the pollution sources are often analyzed separately, preventing the formulation of integrative solutions. This study aimed to quantify the contribution of agriculture to air, river and coastal water pollution by nutrients. A new MARINA-Nutrients model was developed for Europe to calculate inputs of nitrogen (N) and phosphorus (P) to land and rivers, N emissions to air, and nutrient export to seas by river basins. Under current practice, inputs of N and P to land were 34.4 and 1.8 Tg·yr–1, respectively. However, only 12% of N and 3% of P reached the rivers. Agriculture was responsible for 55% of N and sewage for 67% of P in rivers. Reactive N emissions to air from agriculture were calculated at 4.0 Tg·yr–1. Almost two-fifths of N emissions to air were from animal housing and storage. Nearly a third of the basin area was considered as pollution hotspots and generated over half of N emissions to air and nutrient pollution in rivers. Over 25% of river export of N ended up in the Atlantic Ocean and of P in the Mediterranean Sea. These results could support environmental policies to reduce both air and water pollution simultaneously, and avoid pollution swapping.

关键词: agriculture     air-water modeling     European rivers     nutrient pollution     sewage systems     source attribution    

Impacts of building information modeling (BIM) implementation on design and construction performance:

Dongping CAO, Heng LI, Guangbin WANG

《工程管理前沿(英文)》 2017年 第4卷 第1期   页码 20-34 doi: 10.15302/J-FEM-2017010

摘要: Drawing on resource dependence theory, this paper develops and empirically tests a model for understanding how the implementation of building information modeling (BIM) in construction projects impacts the performance of different project participating organizations through improving their interorganizational collaboration capabilities. Based on two sets of survey data collected from designers and general contractors in BIM-based construction projects in China, the results from partial least squares analysis and bootstrapping mediation test provide clear evidence that BIM-enabled capabilities of information sharing and collaborative decision-making as a whole play a significant role in determining BIM-enabled efficiency and effectiveness benefits for both designers and general contractors. The results further reveal that designers and general contractors benefit from project BIM implementation activities significantly non-equivalently, and that this non-equivalence closely relates to the different roles played by designers and general contractors in BIM-enabled interorganizational resource exchange processes. The findings validate the resource dependence theory perspective of BIM as a boundary spanning tool to manage interorganizational resource dependence in construction projects, and contribute to deepened understandings of how and why project participating organizations benefit differently from the implementation of interorganizational information technologies like BIM.

关键词: building information modeling     interorganizational collaboration     construction project performance     resource dependence theory     partial least squares modeling    

Design and modeling of a novel soft parallel robot driven by endoskeleton pneumatic artificial muscles

《机械工程前沿(英文)》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0678-2

摘要: Owing to their inherent great flexibility, good compliance, excellent adaptability, and safe interactivity, soft robots have shown great application potential. The advantages of light weight, high efficiency, non-polluting characteristic, and environmental adaptability provide pneumatic soft robots an important position in the field of soft robots. In this paper, a soft robot with 10 soft modules, comprising three uniformly distributed endoskeleton pneumatic artificial muscles, was developed. The robot can achieve flexible motion in 3D space. A novel kinematic modeling method for variable-curvature soft robots based on the minimum energy method was investigated, which can accurately and efficiently analyze forward and inverse kinematics. Experiments show that the robot can be controlled to move to the desired position based on the proposed model. The prototype and modeling method can provide a new perspective for soft robot design, modeling, and control.

关键词: pneumatic artificial muscles     soft robot     modeling approach     principle of virtual work     external load    

Steam turbine governor modeling and parameters testing for power system simulation

Ying LI, Chufeng PENG, Zenghui YANG

《能源前沿(英文)》 2009年 第3卷 第2期   页码 198-203 doi: 10.1007/s11708-009-0004-2

摘要: The theoretical modeling, parameters test and model correction for a steam turbine (ST) governor are discussed. A set of ST Governor system model for power system simulation is created based on this research. A power system simulation for an actual power grid accident is conducted using this new model and the comparison between the simulation and actual data show that the results are satisfactory.

关键词: power system simulation     ST governor system     modeling     parameters testing    

Electromagnetic interference modeling and suppression techniques in variable-frequency drive systems

Le YANG, Shuo WANG, Jianghua FENG

《机械工程前沿(英文)》 2018年 第13卷 第3期   页码 329-353 doi: 10.1007/s11465-018-0466-1

摘要:

Electromagnetic interference (EMI) causes electromechanical damage to the motors and degrades the reliability of variable-frequency drive (VFD) systems. Unlike fundamental frequency components in motor drive systems, high-frequency EMI noise, coupled with the parasitic parameters of the trough system, are difficult to analyze and reduce. In this article, EMI modeling techniques for different function units in a VFD system, including induction motors, motor bearings, and rectifier-inverters, are reviewed and evaluated in terms of applied frequency range, model parameterization, and model accuracy. The EMI models for the motors are categorized based on modeling techniques and model topologies. Motor bearing and shaft models are also reviewed, and techniques that are used to eliminate bearing current are evaluated. Modeling techniques for conventional rectifier-inverter systems are also summarized. EMI noise suppression techniques, including passive filter, Wheatstone bridge balance, active filter, and optimized modulation, are reviewed and compared based on the VFD system models.

关键词: variable-frequency drive (VFD)     electromagnetic interference (EMI)     motor drive modeling     EMI noise suppression    

An investigation on prevalent strategies for XFEM-based numerical modeling of crack growth in porous

《结构与土木工程前沿(英文)》 2021年 第15卷 第4期   页码 914-936 doi: 10.1007/s11709-021-0750-8

摘要: Crack growth modeling has always been one of the major challenges in fracture mechanics. Among all numerical methods, the extended finite element method (XFEM) has recently attracted much attention due to its ability to estimate the discontinuous deformation field. However, XFEM modeling does not directly lead to reliable results, and choosing a strategy of implementation is inevitable, especially in porous media. In this study, two prevalent XFEM strategies are evaluated: a) applying reduced Young’s modulus to pores and b) using different partitions to the model and enriching each part individually. We mention the advantages and limitations of each strategy via both analytical and experimental validations. Finally, the crack growth is modeled in a natural porous media (Fontainebleau sandstone). Our investigations proved that although both strategies can identically predict the stress distribution in the sample, the first strategy simulates only the initial crack propagation, while the second strategy could model multiple cracks growths. Both strategies are reliable and highly accurate in calculating the stress intensity factor, but the second strategy can compute a more reliable reaction force. Experimental tests showed that the second strategy is a more accurate strategy in predicting the preferred crack growth path and determining the maximum strength of the sample.

关键词: numerical modeling     extended finite element method     porous media     crack growth     stress intensity factor    

标题 作者 时间 类型 操作

Continuous modeling of soil morphology —thermomechanical behavior of embankment dams

Bettina ALBERS, Krzysztof WILMANSKI

期刊论文

Flow and thermal modeling of liquid metal in expanded microchannel heat sink

期刊论文

一种集成的统一建模语言框架

Mohammad ALSHAYEB,Nasser KHASHAN,Sajjad MAHMOOD

期刊论文

Computer modeling of crystal growth of silicon for solar cells

Lijun LIU, Xin LIU, Zaoyang LI, Koichi KAKIMOTO

期刊论文

Lamb wave propagation modeling for structure health monitoring

Xiaoyue ZHANG, Shenfang YUAN, Tong HAO

期刊论文

Building information modeling and its impact on users in the lifeworld: A mediation perspective

Hans VOORDIJK

期刊论文

Integrating storm surge modeling with traffic data analysis to evaluate the effectiveness of hurricane

期刊论文

Hierarchical modeling of stochastic manufacturing and service systems

Zhe George ZHANG, Xiaoling YIN

期刊论文

Structural modeling of a typical gas turbine system

Naresh YADAV, Irshad Ahmad KHAN, Sandeep GROVER

期刊论文

HOTSPOTS OF NUTRIENT LOSSES TO AIR AND WATER: AN INTEGRATED MODELING APPROACH FOR EUROPEAN RIVER BASINS

期刊论文

Impacts of building information modeling (BIM) implementation on design and construction performance:

Dongping CAO, Heng LI, Guangbin WANG

期刊论文

Design and modeling of a novel soft parallel robot driven by endoskeleton pneumatic artificial muscles

期刊论文

Steam turbine governor modeling and parameters testing for power system simulation

Ying LI, Chufeng PENG, Zenghui YANG

期刊论文

Electromagnetic interference modeling and suppression techniques in variable-frequency drive systems

Le YANG, Shuo WANG, Jianghua FENG

期刊论文

An investigation on prevalent strategies for XFEM-based numerical modeling of crack growth in porous

期刊论文