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Optical waveguides in LiNbO_3 and stoichiometric LiNbO_3 crystals by proton exchange

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Science china(Physics,Mechanics & Astronomy) 2008年第10期51卷 1479-1488页

作者： LI ShiLing College of Physics and Engineering, Qufu Normal University, Qufu 273165, china School of Physics and Microelectronics, shandong University, jinan 250100, china 1. College of Physics and Engineering Qufu Normal University Qufu 273165 China 2. School of Physics and Microelectronics Shandong University Jinan 250100 China

The formation of optical planar waveguides in LiNbO3 and stoichiometric LiNbO3 crystals by proton exchange was reported. The prism-coupling method was used to characterize the dark-line spectroscopy at the wavelength of 633 and 1539 nm, re-spectively. The mode optical near-field outputs from proton-exchanged LiNbO3 and SLN waveguides at 633 nm were presented. The mode field from stoichiometric LiNbO3 (SLN) waveguide is lighter and more uniform than that from LiNbO3 waveguide, which means the quality of the waveguide in SLN crystal is better than that of the LiNbO3 waveguide. For proton-exchanged LiNbO3 waveguides, the evo-lution of the refractive index profile with annealing was presented. The disorder profiles of Nb atoms in proton-exchanged LiNbO3 waveguides were obtained by Rutherford backscattering/channeling technique. It is shown that the longer the exchange time, the larger the displacement of Nb atoms.

关键词： optical waveguide proton exchange LiNbO3 crystal stoichiometric LiNbO3 crystal

Polling Algorithm Based on Traffic Burst Characteristics of Broadband Wireless Access Systems

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Journal of Shanghai Jiaotong university(Science) 2011年第4期16卷 429-435页

作者：李秀媛李炜吴晓娟张云峰 School of Computer Science and Technology Shandong Economy University School of Information Science and Engineering Shandong University shandong Provincial Key Laboratory of Digital Media Technology

In this paper,we propose a novel polling algorithm to decrease the number of idle slots and collission slots during the polling cycle by evaluating the bandwidth request of the subscribe stations(SSs) in the next polling cycle for broadband wireless access(BWA) *** firstly analyze the feature of silent time intervals and deduce the Hurst index which symbolizes the degree of self-similarity and long-relative *** we represent the inactive OFF time intervals by the Pareto model and estimate the shape parameterαby the group measured *** we can evaluate the transmission probability of a silent SS before the next polling cycle. By this algorithm,we can find the optimal transmission opportunities for the base station(BS) to achieve the least collision or void timeslots in order to achieve the largest bandwidth *** theoretical analysis and simulation results show that this polling algorithm can improve the performance for BWA system.

关键词： broadband wireless access(BWA) systems polling algorithm bandwidth allocation self-similarity

Gradual solution heat treatment of AlSiCuMg cast alloys

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Rare Metals 2003年第4期22卷 304-308页

作者： WANG Guiqing , BIAN Xiufang ,and ZHANG Junyan1) The Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, shandong University, jinan 250061, china2) Department of Material Science and Technology, shandong Architectural Engineering Institute, jinan 2.0014, china shandong University The Key Laboratory of Liquid Structure and Heredity of MaterialsMinistry of Education Jinan 250061

The microstructure characteristics of AlSiCuMg cast alloys were studied withdifferent Cu content and the gradual solution treatment by DSC, SEM, TEM and mechanical method. Themelting point of alpha (Al) + Si decreases and polynary eutectic phases with low melting point formwith increase of Cu content. Gradual solution treatment includes two steps: solution treating nearthe melting point of polynary eutectic phase to take it dissolve first, and then increasing solutiontemperature to take the remainder copper intermetallics dissolved into alpha (Al). Grain boundariesmelting can be avoided by gradual solution treatment, even the maximum solution temperature isabove final solidification point, and the age hardening response increases correspondingly

关键词： aluminum alloy gradual solution heat treatment differential scanningcalorimetry (DSC) polynary eutectic phase

Capped carbon nanotube-based molecular switch

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Science Bulletin 2010年第13期55卷 1227-1230页

作者： ZHAO Peng1, WANG PeiJi1, ZHANG Zhong1 & LIU DeSheng2 1 School of Science, University of jinan, jinan 250022, china 2 School of Physics, State Key Laboratory of Crystal Materials, shandong University, jinan 250100, china School of Science University of Jinan Jinan 250022 China School of Physics State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China

Using the Landauer formalism that combines both the non-equilibrium Green's function (NEGF) and first-principles density functional theory (DFT), the electron transport characteristics of one-dimensional molecular switching device based on the capped carbon nanotubes have been investigated. The results show that the transmission can be efficiently tuned within two orders of magnitude just by changing 0.2 nm of the tube-tube separation. Moreover, the electron transport is insensitive to the topology of the facing conformations which can improve the practical stability of the chosen system as a molecular switch.

关键词： carbon nanotube molecular switch non-equilibrium Green function density functional theory

Correlation between Structures of Bulk Amorphous Zr-Ti-Ni-Cu-Be Alloy in Different States

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Journal of Materials Science & Technology 2001年第1期17卷 93-94页

作者： Xuelei TIAN and Xichen CHEN Institute of Mater. Sci. & Eng., shandong University of Technology, jinan 250061, china shandong Univ Technol Inst Mat Sci & Engn Jinan 250061 Peoples R China

The structures of the bulk amorphous Zr41Ti14Cu12.5Nil0.0Be22.5 alloy have been analyzed in solid, supercooled liquid and liquid with X-ray diffraction. The first coordination sphere radii and the first coordination numbers are 0.312 um, 11.2 in solid state.10.932 nm, 10.932 in supercooled liquid region and 0.305 urn, 11.296 in liquid state. The structures are the same in different states. But it shows some tendency to crystallizing that the first coordination sphere radius and the first coordination number drop in supercooled liquid region.

关键词： Ti Zr Correlation between Structures of Bulk Amorphous Zr-Ti-Ni-Cu-Be Alloy in Different States Cu

EFFECT OF COOLED BOUNDARY ON THE TURBULENT STRUCTURE

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Journal of Hydrodynamics 2003年第5期15卷 54-59页

作者： Li Guo xiang, Mao Hua yong, Li Na School of Energy and Power Engineering, shandong University, jinan 250061, china, School of Energy and Power Engineering Shandong University Jinan 250061 China

The flow field in the cooled channel of a heat exchanger was measured usingthe X-type film probes of Hot Wire/Firm Anemotheter, and the turbulent mechanism was discussed. Itis concluded that the airflow is cooled in the flow process, the distribution of the turbulentintensity is relatively convergent near the centcrline and the boundary, the constriction actionproduced due to heat release at the foot of the fins causes u to decrease and w to increase near theroot downstream. It is concluded that the turbulent flow with cooled boundary results from thebalance of production, dissipation and intermittency caused by constriction action.

关键词： heat exchanger cooling turbulent structure

Characterization of tensile fracture in heavily alloyed Al-Si piston alloy

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Progress in Natural Science:Materials International 2011年第5期21卷 380-385页

作者： Guo-hua ZHANG~(1,2),Jian-xin ZHANG~3,Bing-chao LI~3,Wei CAI~1 1.School of Materials Science and Engineering,Harbin Institute of Technology,Harbin 150001,china 2.shandong Binzhou Bohai Piston Co.,Ltd,Binzhou 256602,china 3.School of Materials Science and Engineering,shandong University,Ji'nan 250061,china [a] School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China [b] shandong Binzhou Bohai Piston Co. Ltd Binzhou 256602 China [c] School of Materials Science and Engineering Shandong University Ji'nan 250061 China

This paper focuses on a typical automotive piston material to characterize its fractographic appearance after tensile rupture. The fracture of this heavily alloyed Al—Si alloy takes place in a brittle *** consecutive eutectic zone is found to break by debonding of Si platelets from the Al matrix or by fracturing of Si *** various intermetallic particles break up complicatedly under the stress field of the propagating *** fracture tends to pass through or approach to the boundary between the eutectic Al matrix and Si platelets and there is a strong interaction between the propagating crack and the obstructing intermetallic compound.A tensile fracture mechanism in the heavily alloyed Al-Si alloy is elucidated.

关键词： tension test aluminum alloys facets fracture

STATE-FEEDBACK ADAPTIVE STABILIZING CONTROL DESIGN FOR A CLASS OF HIGH-ORDER NONLINEAR SYSTEMS WITH UNKNOWN CONTROL COEFFICIENTS

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Journal of Systems Science & Complexity 2007年第3期20卷 350-361页

作者： Zongyao SUN Yungang LIU School of Control Science and Engineering Shandong University Jinan 250061 China.

In this paper, a new approach is successfully addressed to design the state-feedback adaptive stabilizing control law for a class of high-order nonlinear systems in triangular form and with unknown and nonidentical control coefficients, whose stabilizing control has been investigated recently under the knowledge that the lower bounds of the control coefficients are exactly known. In the present paper, without any knowledge of the lower bounds of the control coefficients, based on the adaptive technique and appropriately choosing design parameters, we give the recursive design procedure of the stabilizing control law by utilizing the approach of adding a power integrator together with tuning functions. The state-feedback adaptive control law designed not only preserves the equilibrium at the origin, but also guarantees the global asymptotic stability of the closed-loop states and the uniform boundedness of all the other closed-loop signals.

关键词： Adaptive stabilizing control adding a power integrator high-order nonlinear systems,state-feedback unknown control coefficients.

Size Determination of Ultramicropores and Small Mesopores Using a Calculation Procedure Based on the Tangents of Comparison Plot

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Journal of Wuhan University of Technology(Materials Science) 2010年第3期25卷 391-394页

作者：邱芹刘世权 School of Materials Science and Engineering University of Jinan

Pore size distribution（PSD） curves of synthesized hollow silica spheres with ultrmicropores and small mesopores were obtained from calculations based on the BJH,KJS,SF,MP,NLDFT models and ***＇s *** indicate that Zhu＇s method not only gives reasonable small mesopore size but also could be further extended to the ultramicropores region for the PSD evaluation.

关键词： pore size distribution comparison plot ultramicropores mesopores