237 results
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2. 3D Modeling of the Different Boiling Regimes During Spill and Spreading of Liquid Hydrogen.
- Author
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Jaekel, C., Verfondern, K., Kelm, S., Jahn, W., and Allelein, H.-J.
- Subjects
EBULLITION ,LIQUID hydrogen ,ELECTRIC power production ,ENERGY storage ,MATHEMATICAL models ,ENERGY industries ,NUCLEATION - Abstract
Abstract: In a future energy generation market, the storage of energy is going to become increasingly important. Besides classic ways of storage, like pumped storage hydro power stations, etc, the production of hydrogen will play an important role as an energy storage system. Hydrogen may be stored as a liquefied gas (LH2) on a long term base as well as for short term supply of fuel stations to ensure a so called “green” mobility. The handling with LH2 has been subject to several recent safety studies. In this context reliable simulation tools are necessary to predict the spill and spreading of LH2 during an accidental release. This paper deals with the different boiling regimes: film boiling, transition boiling and nucleation boiling after a release and their modeling by means of an inhouse-code for wall evaporation, which is implemented in the commercial CFD code ANSYS CFX. The paper will describe the model, its implementation and validation against experimental data, such as the HSL LH2 spill experiments [1]. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
3. Experimental Study And Simulation Of Airflow In Solar Chimneys.
- Author
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Saifi, Nadia, Settou, Noureddine, Dokkar, Boubekeur, Negrou, Belkhir, and Chennouf, Nasreddine
- Subjects
CHIMNEYS ,COMPUTATIONAL fluid dynamics ,FINITE volume method ,AIR flow ,SIMULATION methods & models ,MATHEMATICAL models ,PERFORMANCE evaluation - Abstract
Abstract: A detailed mathematical simulation and experimental investigation of airflow in solar chimneys is studied in this paper. Several experimental studies were carried out on the solar chimney; their choice depends on the parameter of the design and the thermal performances for different geometrical configurations. The experimental tests show that the field speeds in the chimney is influenced by the width of the channel and also of the angle of inclination of the chimney. Therefore, investigations have been carried out in this paper to find the effect of inclination on the performance of solar chimney in Ouargla Province, Algeria. The simulation of this problem is implemented into the commercial CFD code Fluent 6.3. 26. The conservation equations of mass, continuity and energy are solved by the Finite Volume Method. The validation of the results is presented. An good agreement between the experimental results and simulation ones is observed. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
4. The Design and Optimization for The Dome of Tidal Turbine.
- Author
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Lu, Hong-bo, Li, Yong-lin, Ma, Liang-liang, and Pao, Xiu-ling
- Subjects
ENGINEERING design ,MATHEMATICAL optimization ,WIND turbines ,OCEAN currents ,MATHEMATICAL models ,NUMERICAL analysis ,SIMULATION methods & models - Abstract
Abstract: This paper uses Diffuser Augmented Wind Turbine for reference. According to the characteristics of ocean current movement, this paper gives several dome model programs for the straight blade vertical-axis tidal turbine. Make use of it to increase its output power. This paper gives several dome model programs for the straight blade vertical-axis tidal turbine. And optimum scheme is chosen by numerical simulation. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
5. Numerical and Experiment Research for Soft Coal under Condition of Blending Lignite.
- Author
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Lv, Tai, Wang, Qian, and Leng, Jie
- Subjects
NUMERICAL analysis ,LIGNITE ,MIXING ,MATHEMATICAL models ,COAL combustion ,SIMULATION methods & models ,TEMPERATURE effect - Abstract
Abstract: The paper adopts standard
k−ɛ turbulence model and other mathematical models, and completing the blending lignite combustion numerical simulation of 600 MW boiler of one power plant. Three conditions were simulated in this paper, and these three conditions were compared and analyzed, the basic conclusion is consistent with the test. The result shows that the combustion character of blending lignite is lower than burning soft coal. Burning lignite shows a decline furnace temperature, and the simulation results are consistent with the experimental results. Pay attention to adjust the reasonable operating manner, and the operation is safety and economic. At the same time this paper also provides a useful reference for researching tangentially fired boiler furnace process. [Copyright &y& Elsevier]- Published
- 2012
- Full Text
- View/download PDF
6. The Generation of New Words Prevailing on the Internet and Its Revelation to the Innovation Environment Cultivation.
- Author
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Zhiwei, Yu
- Subjects
COMPUTER networks ,INTERNET users ,TECHNOLOGICAL innovations ,MATHEMATICAL models ,VIRTUAL reality ,AMUSEMENTS - Abstract
Abstract: With the widespread popularity and application of the network, the new words appear on the internet one after another. The research on the generation of new words on the network has been a revelation to the innovation environment cultivation. This paper summarizes the type and the producing process of the new words on the internet, analyzes the innovation environment of new words on the network, and builds an innovation environment model of new words on the network from network environment, the structure of the internet users, the entertainment and virtual features of the network communication. On the basis of it, the paper discusses the innovation environment building in the context of the network and proposes to create a broad-based participation, free exchange, and timely sharing and dissemination innovation environment. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
7. Efficient Context Modeling Using OWL in Mobile Cloud Computing.
- Author
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Changboka, Chang, Hyokyung, Ahn, Hyosik, and Choi, Euiin
- Subjects
CLOUD computing ,CELL phones ,INFORMATION technology ,MOBILE apps ,INFORMATION processing ,MATHEMATICAL models ,SMARTPHONES ,COMPUTER users - Abstract
Abstract: Mobile Cloud Computing has become as a new IT paradigm because of the growth of mobile device like smartphone and appearance of Cloud Computing environment. This mobile cloud environment provides various services and IT resources according to users’ requests, so an effective management of service and IT resources is required. Hence, this paper designs a context model based on ontology in mobile cloud computing in order to provide distributed IT resources and services to users based on context-awareness information. As the context model proposed in this paper uses context-aware information, it enables to provide more accurate personalized services and manage distributed IT resources. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
8. Analysis on Three-Dimensional Numerical Simulation of Turbine Flow Characteristics.
- Author
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Jianhong, Fu, Kexiong, Song, Zhi, Zhang, Zhiqiang, Zhao, Dezhi, Zeng, Fei, Liu, and Xin, Zheng
- Subjects
TURBINES ,THREE-dimensional display systems ,COMPUTER simulation ,MATHEMATICAL models ,COMPUTATIONAL fluid dynamics ,VISCOSITY ,PARAMETER estimation - Abstract
Abstract: By the use of modelling software, this paper set up the three-dimensional physical model of single-stage turbine and guided it into the pre-process software. After meshing the turbine flow channel, simulating the mud flow characteristics in Turbine with CFD, and calculating the pressure drawdown at the inlet/outlet and the pressure distributions in single-stage turbine. Such results indicate that the pressure drawdown of single-stage turbine is influenced by the mud discharge capacity, drilling fluid density and viscosity. The pressure drop increases with the augment of mud discharge, which is approximately linear. There are significantly positive correlations between the pressure drawdown and the increase of mud density. The research in the paper provides reliable guidance in turbine flow channel design and the drilling technological parameters optimizing. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
9. Fuzzy Entropy Clustering Approach to Evaluate the Reliability of Emergency Logistics System.
- Author
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Gong, Bengang, Chen, Xiang, and Hu, Chaozhong
- Subjects
FUZZY logic ,BUSINESS logistics ,ENTROPY (Information theory) ,RELIABILITY in engineering ,MATHEMATICAL models ,CLUSTER analysis (Statistics) - Abstract
Abstract: Because of burstiness, weak economy, time-uncertain of emergency logistics system, the paper constructs the operation model and its evaluation index system for emergency logistics system. In view of the imperfection of subjective determining index weight method in traditional evaluation, the index weight coefficients are determined by information entropy method of combining subjective judgment with objective evaluation. Then the fuzzy clustering and information entropy to determine the weights are used into emergency logistics system reliability evaluation. Finally the paper obtains a specific solution steps based on an example. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
10. Pose Accuracy Calibration of a Serial Five DOF Robot.
- Author
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Yin, Jian and Gao, Yu
- Subjects
CALIBRATION ,ROBOTS ,PERFORMANCE evaluation ,DEGREES of freedom ,MEASUREMENT errors ,KINEMATICS ,MATHEMATICAL models ,PARAMETER estimation - Abstract
Abstract: Robot is widely used in industrial domain and pose accuracy of end-effector is an important indicator for judging robot performance. Calibration is a necessary for operating industrial robot and an effective and efficient means of accuracy improvement. This paper describes the development of a calibration procedure for a five degree of freedom serial robot using the laser tracker. The main goal of this paper is to utilize measurements relative to the end-effector of the robot to compensate errors. The robot kinematic model is computed to help identify the deviations. Robot parameter deviations can be identified so that the nominal parameters can be corrected. The experimental results are validated effectively. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
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