Papers by Keyword: Parameter

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Authors: Rong Xia Wang, Hong Jiang Li
Abstract: The mechanical property of external prestressed beams is affected by many parameters. Based on experimental study on externally strengthened prestressed box beams, a three-dimensional finite element analysis model was built in ANSYS. The calculation results was proved to be correct by being compared with experimental results. The effect of some parameters on deflection and stress in externally strengthened box beam was deeply analyzed in serviceability stage and ultimate status. The study shows that different original status of strengthened beam may affect the deflection and stress in different degree. The parameters change, such as effective prestress, concrete strength, the area and depth of external tendons and displacement coupling character for contact node, will result in a little difference in deflection and stress in serviceability stage, but obvious in ultimate status. For box beams in the model, changing the tendons lateral distance to the web results in litlle change in deflection and stress. No matter it is inside or outside the box at cross section.
Authors: Hong Jie Hu, Chao Zhang, Ye Wu, Xiong Jun Wu
Abstract: The rapidity and tracking accuracy of the stabilized tracking system are mainly influenced by nonlinearity Currently, various methods has concentrated on nonlinear compensation such as optimal control and sliding mode variable structure. However, the optimal control method needs precise mathematical model, and sliding mode variable structure method leads to fluctuations of the output. Thus, this paper firstly builds a physical model of the tracking system, and then designs a differential ahead and disturbance observer (DOB) controller for stabilization loop, and a disturbance observer is used to compensate nonlinearity. A case study of a single-axis motion simulator is presented to validate the proposed method. The experiment result shows that the proposed method can obviously improve the stabilized tracking platforms performance in terms of accuracy and fast tracking ability.
Authors: Hu Qi, Yun Gui Li, Xi Lin Lu
Abstract: In this paper, an efficient method is proposed to determine the value of the parameters for the Plastic Damage Model previously proposed by authors. With the proposed method the users can get the value of all the model parameters if only know the uniaxial tension strength, compression strength and elastic modulus of the concrete material. Finally, through several numerical simulations it is proved that the proposed method is effective and the constitutive model using the parameters which determined by the proposed method has the capability of simulating typical nonlinear performances of concrete material.
Authors: Chao Shang, Ke Yin Wang, Hai Ying Huang, Yu Kun Chen
Abstract: The computer simulation has become an important means to study fire broke out and its law of development today. Fire Dynamics Simulator is three-dimensional computational fluid dynamics software based on LES. And it is widely used in the field of fire science. However, it is rarely used in the study of forest fires. Through the study of tree morphological parameters,combined with the modeling features of the pre and post-processing graphical software PyroSIM, this article explored a tree modeling method for FDS.
Authors: Hui Juan Bian, Zhi Dong Qi, Liang Shan, Bo Yang Leng
Abstract: Aiming at a kind of special object with fractional characteristics,a new kind of fractional order PIλ-PDμ controller is put forward in this paper,In this control system, the forward channel of system contains a fractional order PIλ controller,while the feedback loop adopts PDμ controller.The control structure in this fractional order system can achieve a good performance of the closed loop control.Moreover,the impacts on system dynamic performance and static performance are compared when the parameters in the controller are changed.The results show that when these parameters are in the reasonable range,the system can achieve better control performance.
Authors: Shao Hua Zhen, Li Bao An, Yan Yan Liu
Abstract: Study of the effect of dielectrophoresis (DEP) parameters is important in high-precision DEP assembly of carbon nanotubes (CNTs). The DEP parameters usually considered in the literature include the magnitude and frequency of the applied voltage, the assembly time, the concentration of the CNT suspension, and the geometry of the electrodes. This paper reviews the current progresses on both numerical and experimental study of the CNT assembly by DEP, especially the influence of the DEP parameters on the assembly process and results. The review shows that the magnitude of the applied voltage affects the DEP force and the number of deposited CNTs. The assembly time and CNT concentration influence the density of deposited CNTs. Different electrode geometries have an effect on the distribution of the electric field. The electrode spacing changes the field strength and the direction of the field gradient. The related discussion is presented as well.
Authors: Yuan Wei Lu, Li Hua Liu, Yu Ting Wu, Chong Fang Ma, Jing Fu Wang, Long Long Zhou
Abstract: In order to develop small-scale natural gas liquefaction equipment, a small expansion natural gas liquefaction process was designed, which was based on the technical parameters of the single screw compressor and expander developed by Beijing University of Technology. The effect of the key parameters on the natural gas liquefaction rate and specific power consumption was simulated and optimized. The results showed that the liquefaction rate of the process can reach 100% and the specific power consumption was relatively low under the optimal operation conditions. These research results can provide theoretical basis for the design of small-scale natural gas liquefaction equipment.
Authors: Ruzaidi Zamri, N. Ismail, B.T. Hang Tuah bin Baharudin, Mohamed Ariff Azmah Hanim, Anton Satria Prabuwono
Abstract: Polishing is a secondary process in machining. The application of polishing process is crucial to obtained final appearance of a product. This study addresses parameter analysis on flat and dry polishing to determine the most influence parameter which effect surface roughness. For this purpose, Design of Experiment (DOE) is used as a methodology in the analysis. The polishing process is conducted on Comau robotic cell and the combination of grit size, polishing time and polishing force are subjected on the material by using pneumatic polishing tool. Two-level factorial experiment design is conducted and result is interpreted by using statistical software. From the result it is shown that grit size and polishing time give the main effect on surface roughness. However for 2-way interaction effect, polishing time and polishing force contribute significantly on surface roughness. This suggested that for flat and dry polishing, consideration on these parameters is an essential aspect in order to achieve a good surface finished.
Authors: Pablo J. Silva, Leonardo M. Leodido, Cosme Roberto Moreira Silva
Abstract: The incremental sheet forming allows the production in high quality of extremely complex pieces of steel, aluminum, titanium and many other materials, in order to reduce time and costs of production and cost of tooling used in low production. Working with tools of various diameters and a suitable machine programming is possible to produce complex parts of small lots in few hours, which in conventional stamping process would take days. This paper aims to introduce process parameters and analyze results from practice tests and computational analysis by changing the rotation, advancement in XY and Z advancement, tooling options, fixture plate and forming tool for producing pieces of varying size and complexity in the shortest time and at the highest quality possible. Thus, presents the incremental sheet forming as an alternative for rapid prototyping, as well as its devices and tools.
Authors: Xiang Gu, Shang Ying Xie, Shao Min Jia
Abstract: In the modern urban bridge projects,especially the urban interchange projects and the urban viaduct projects,the long-span curved bridge with the small radius is often inevitably used,considering the transportation under bridges,pipelines and aesthetic factors.This kind of long-span curved bridge with small radius was adopted on the south of Second Ring Road in Chendu of the project of "Two Expressways,Two Extended Roads,Two Ring Roads".The influence,which the change of the parameters on the structure had,was analyzed by using the finite element software of Midas Civil 2010.Then,the parameter which had greatest impact on the inner force of the structure was found.The girder depth is the key parameter in design.
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