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Decentralized Traffic Control Using Agents in Ethernet Passive Optical Networks (EPON)

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Communications and Network 2016年第3期8卷 193-203页

作者： Sajaa K. Sadon Hizamel M. Hizan Thavamaran Kanesan Romli Mohamad System Technologies lab Communication Technology Telekom Research & Development SdnBhd TMR & D Innovation Centre Lingkaran Teknokrat Timur Cyberjaya Malaysia

Traditionally, allocating of Ethernet Passive Optical Network (EPON) bandwidth schemes relied on a centralized architecture where their Optical Line Terminal (OLT) is the sole intelligent device with the capability for the arbitration of bandwidth based on time-division access for the upstream shared channel. However, any breakdown in the OLT bandwidth allocation will affect the allotment for Optical Network Units (ONUs). Few researches had dealt with a decentralized approach for the EPON and most of the solutions proposed involved additional cost by adding new complex devices to the original architecture. This paper proposes an intelligent decentralized mechanism in EPON that enhances the network performance using intelligent agents specification based on the IEEE 802.3 ah standards in the foundation for intelligent physical agent which is compatible with an Internet Protocol (IP)-based network. Specifically, this paper proposes a novel distributed scheme that supports differentiated services and ensures QoS for both Inter-and Intra- ONU allocation. The proposed mechanism introduces a unique direct communication between the ONUs supported by identical dynamic bandwidth allocation algorithms running simultaneously in each ONU. In addition to being fully distributed, the proposed scheme is asynchronous, scalab.e, and dynamic with flexibility and reliability in handling data, voice and video.

关键词： Agents Decentralized DBA Diffserv Distributed Systems EPON

Numerical simulations of shake-table experiment for dynamic soil-pile-structure interaction in liquefi able soils

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Earthquake Engineering and Engineering Vibration 2014年第1期13卷 171-180页

作者： Tang Liang Baydaa Hussain Maula Ling Xianzhang Su Lei Key lab.of Structures Dynamic Behavior and Control(Harbin Institute of Technology) Ministry of Education School of Civil Engineering Harbin Institute of Technology

A shake-table experiment on pile foundations in liquefi able soils composed of liquefi able sand and overlying soft clay is studied. A three-dimensional(3D) effective stress fi nite element(FE) analysis is employed to simulate the experiment. A recently developed multi-surface elasto-plastic constitutive model and a fully coupled dynamic inelastic FE formulation(u-p) are used to model the liquefaction behavior of the sand. The soil domains are discretized using a solid-fl uid fully coupled(u-p) 20-8 noded brick element. The pile is simulated using beam-column elements. Upon careful calibration, very good agreement is obtained between the computed and the measured dynamic behavior of the ground and the pile. A parametric analysis is also conducted on the model to investigate the effect of pile-pinning, pile diameter, pile stiffness, ground inclination angle, superstructure mass and pile head restraints on the ground improvement. It is found that the pile foundation has a noticeable pinning effect that reduces the lateral soil displacement. It is observed that a larger pile diameter and fi xed pile head restraints contribute to decreasing the lateral pile deformation; however, a higher ground inclination angle tends to increase the lateral pile head displacements and pile stiffness, and superstructure mass seems to effectively infl uence the lateral pile displacements.

关键词： liquefaction pile pinning soil improvement pile deformation earthquake nonlinear fi nite element method shake-table experiment

Simplified design method and seismic performance of space trusses with consideration of the influence of the stiffness of their lower supporting columns

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Earthquake Engineering and Engineering Vibration 2016年第2期15卷 401-409页

作者： Fan Feng Sun Menghan Zhi Xudong Key lab.of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology School of Civil Engineering Harbin Institute of Technology

Static and dynamic force performance of two types of space truss structures i.e. square pyramid space truss（SPST） and diagonal on square pyramid space truss（DSPST）, are studied to determine the effect of stiffness of their lower supporting members. A simplified model for the supporting columns and the equivalent spring mass system are presented. Furthermore, the feasibility of the simplified model is demonstrated through theoretical analysis and examples of comparative analysis of the simplified model with the entire model. Meanwhile, from the elastic analysis under frequently occurring earthquakes and elasto-plastic analysis under seldom occurring earthquakes subjected to TAFT and EL-Centro seismic oscillation it is shown that the simplified method can be encompassed in the results from the normal model. It also showed good agreement between the two methods, as well as greatly improved the computational efficiency. This study verified that the dynamic effect of the supporting structures was under considered in space truss design in the past. The method proposed in the paper has important significance for other space truss structures.

关键词： simplified supporting pyramid stiffness truss verified diagonal elasto columns seldom

Damage constitutive model of different age concretes under impact load

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Journal of Central South University 2015年第2期22卷 693-700页

作者：李夕兵王世鸣翁磊黄麟淇周韬周健 School of Resources and Safety Engineering Central South University Hunan Key lab.of Resources Exploitation and Hazard Control for Deep Metal Mines

In order to investigate the mechanical properties and stress-strain curves of concrete at different ages under impact load,the impact compression tests of concrete at age of 1, 3, 7, 14 and 28 d were conducted with a large diameter split Hopkinson pressure bar, respectively. Based on statistical damage theory and Weibull distribution, combining the analysis of the change laws of stressstrain curves and viscosity coefficient of concrete with age, a damage constitutive model that can reflect the variation in dynamic mechanical properties with age was proposed. The stress-strain curves calculated from the proposed model are in good agreement with those from experimental data directly.

关键词：损伤本构模型冲击载荷混凝土年龄 Weibull分布应变曲线霍普金森压杆动态力学性能

Feasibility Study on Chemical Flooding in Super High Porosity and Permeability Heavy Oil Reservoir

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Journal of Materials Science and Chemical Engineering 2020年第11期8卷 43-53页

作者： Juan Zhao Jian Zhang Guang Yang China State Key lab.of Offshore Oil Exploitation Beijing China CNOOC research Institute CO. Ltd. Beijing China

In this paper, the feasibility study of chemical flooding is carried out for ultra-high porosity and high permeability heavy oil field with permeability higher than 10 μm2 and porosity greater than 35%. The viscosity-concentration relationship of four kinds of oil flooding systems such as hydrolyzed polyacrylamide, structural polymer A, structural polymer B and gel was studied. The results showed that the viscosity of ordinary polymer and structural polymer B was lower compared with other two types of oil displacement agents, and the viscosity of structural polymer A was higher. The higher the concentration, the higher the viscosity retention rate. The gel system has the highest viscosity and best anti-shear ability. The resistance coefficient and residual resistance coefficient of structural polymer A and gel system were further studied. The results show that permeability, velocity and polymer concentration all affect the resistance coefficient and residual resistance coefficient. From the point of view of resistance establishment ability, it is considered that structural polymer A is not suitable for permeability formation above 10 μm2. Gel system has stronger ability to establish resistance coefficient than structural polymer A flooding system, and it is more feasible for formation system with permeability above 10 μm2.

关键词： Super High Porosity and High Permeability Chemical Flooding Viscosity-Concentration Relationship Resistance Coefficient Coefficient of Residual Resistance

Dynamic Analysis of Propulsion Mechanism Directly Driven by Wave Energy for Marine Mobile Buoy

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Chinese Journal of Mechanical Engineering 2016年第4期29卷 710-715页

作者： YU Zhenjiang ZHENG Zhongqiang YANG Xiaoguang CHANG Zongyu College of Engineering Ocean University of China Qingdao 266100 China Key lab.of Ocean Engineering of Shandong Province Qingdao 266100 China

Marine mobile buoy（MMB） have many potential applications in the maritime industry and ocean *** progress has been made,however the technology in this area is far from maturity in theory and faced with many difficulties in application.A dynamic model of the propulsion mechanism is very necessary for optimizing the parameters of the MMB,especially with consideration of hydrodynamic *** principle of wave-driven propulsion mechanism is briefly *** set a theory foundation for study on the MMB,a dynamic model of the propulsion mechanism of the MMB is *** responses of the motion of the platform and the hydrofoil are obtained by using a numerical integration method to solve the ordinary differential equations.A simplified form of the motion equations is reached by omitting terms with high order small *** relationship among the heave motion of the buoy,stiffness of the elastic components,and the forward speed can be obtained by using these simplified *** dynamic analysis show the following：The angle of displacement of foil is fairly small with the biggest value around 0.3 rad;The speed of mobile buoy and the angle of hydrofoil increased gradually with the increase of heave motion of buoy;The relationship among heaven motion,stiffness and attack angle is that heave motion leads to the angle change of foil whereas the item of speed or push function is determined by vertical velocity and angle,therefore,the heave motion and stiffness can affect the motion of buoy significantly if the size of hydrofoil is kept *** proposed model is provided to optimize the parameters of the MMB and a foundation is laid for improving the performance of the MMB.

关键词： propulsion mechanism marine mobile buoy dynamic model hydrodynamics Morision's equation

Prediction of Load-Displacement Curve of Flexible Pipe Carcass Under Radial Compression Based on Residual Neural Network

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China Ocean Engineering 2023年第1期37卷 42-52页

作者： YAN Jun LI Wen-bo Murilo Augusto VAZ LU Hai-long ZHANG Heng-rui DU Hong-ze BU Yu-feng State Key lab.ratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsDalian University of TechnologyDalian 116024China Ningbo research Institute of Dalian University of Technology Ningbo 315016China Ocean Engineering Program Federal University of Rio de JaneiroRio de Janeiro 21941-901Brazil

The carcass layer of flexible pipe comprises a large-angle spiral structure with a complex interlocked stainless steel cross-section profile, which is mainly used to resist radial load. With the complex structure of the carcass layer, an equivalent simplified model is used to study the mechanical properties of the carcass layer. However, the current equivalent carcass model only considers the elastic deformation, and this simplification leads to huge errors in the calculation results. In this study, radial compression experiments were carried out to make the carcasses to undergo plastic deformation. Subsequently, a residual neural network based on the experimental data was established to predict the load-displacement curves of carcasses with different inner diameter in plastic states under radial *** established neural network model’s high precision was verified by experimental data, and the influence of the number of input variables on the accuracy of the neural network was discussed. The conclusion shows that the residual neural network model established based on the experimental data of the small-diameter carcass layer can predict the load-displacement curve of the large-diameter carcass layer in the plastic stage. With the decrease of input data, the prediction accuracy of residual network model in plasticity stage will decrease.

关键词： flexible pipe carcass radial compression experiment load−displacement curves residual neural network

A Novel Unsupervised Two-Stage Technique in Color Image Segmentation

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Chinese Journal of Electronics 2018年第2期27卷 405-412页

作者： LONG Peng LU Huaxiang WANG An lab.of Artificial Networks Institute of Semiconductors CAS CAS Center for Excellence in Brain Science and Intelligence Technology University of Chinese Academy of Sciences

A new unsupervised two-stage method for color image segmentation is proposed. The method contains coarse segmentation and delicate segmentation. In coarse segmentation, we adaptively choose a gray channel from CIE-lab.color space. The Otsu method combined with a refinement to its threshold is applied to get global optimal segmentation. In delicate segmentation, a narrowband based procedure is applied to get more accurate contour of the object and local optimal segmentation is achieved. Our method finally balance the global optimal and the local optimal. The proposed method does not need initial contours or initial lab.ls, thus it is more robust in certain applications. Experimental results of our method in MSRA1000 database show that our method is robust in segmenting objects and backgrounds when possessing weakly heterogeneous color. Our method firstly achieves global optimal and then achieves local optimal which draws a new and prospective outlook for segmenting color images.

关键词： Color image segmentation Coarse segmentation Delicate segmentation Narrowband

Controlled synthesis of high-quality W-Y2O3 composite powder precursor by ascertaining the synthesis mechanism behind the wet chemical method

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Journal of Materials Science & Technology 2020年第1期36卷 118-127页

作者： Zhi Dong Nan Liu Weiqiang Hu Zongqing Ma Chong Li Chenxi Liu Qianying Guo Yongchang Liu State Key lab.of Hydraulic Engineering Simulation and Safety School of Materials Science and EngineeringTianjin UniversityTianjin300072China

As an emerging preparation technology,wet chemical method has been employed widely to produce lots of alloy materials such as W and Mo based alloys,owing to its unique technical *** the synthesis mechanism behind wet chemical method is indispensable for controlled synthesis of highquality W-Y2 O3 composite powder *** co-deposition mechanism of yttrium and tungsten component behind the wet chemical method of preparing yttrium-doped tungsten composite nanopowder was investigated systematically in this work.A series of co-deposited composite powders fabricated under different acidity conditions were used as research targets for investigating the effect of surface composition and structure on co-deposition *** was found that white tungstic acid has more W-OH bonds and much higher co-deposition efficiency with Y^3+ions than yellow tungstic *** is illustrated that the coordination reaction between W-OH bonds on tungstic acid particles and Y^3+ions brings the co-deposition of yttrium and tungsten component into *** displacing H^+ions in W-OH bonds,Y^3+ions can be adsorbed on the surface of or incorporated into tungstic acid particles in form of ***,to control and regulate Y2 O3 content in powder precursor accurately,H^+ion concentration in wet chemical reaction should be in range of 0.55-2.82 mol L^-1 to obtain white tungstic ***,H^+ion concentration also has prominent effect on the grain size and morphology of reduced powder *** optimal value should be around 1.58 mol L^-1,which can lead to minimum W grain size(about 17 nm) without bimodal *** chemical mechanism proposed in this work could produce great sense to preparation of high-quality precursor for sintering high-performance Y2 O3 dispersion strengthened W based *** work may also shed light on the approach to exploit analogous synthesis mechanism in other alloy systems.

关键词： W-Y2O3 Wet chemical method W-OH bond Ligand Co-deposition mechanism