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Design and Preparation of Bone Tissue engineering Scaffolds with Porous Controllable Structure

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Journal of Wuhan University of Technology(Materials Science) 2009年第2期24卷 174-180页

作者：林柳兰 College of Mechatronics engineering and Automation Shanghai University

A novel method of designing and preparing bone tissue engineering scaffolds with controllable porous structure of both macro channels and micro pores was proposed. The CAD software UG NX3.0 was used to design the macro channels＇ shape, size and distribution. By integrating rapid prototyping and traditional porogen technique, the macro channels and micro pores were formed respectively. The size, shape and quantity of micro pores were controlled by porogen particulates. The sintered β-TCP porous scaffolds possessed connective macro channels of approximately 500 μm and micro pores of 200-400 μm. The porosity and connectivity of micro pores became higher with the increase of porogen ratio, while the mechanical properties weakened. The average porosity and compressive strength offl-TCP scaffolds prepared with porogen ratio of 60wt% were 78.1.% and 0.2983 MPa, respectively. The cells＇ adhesion ratio of scaffolds was 67.43%. The ALP activity, OCN content and cells micro morphology indicated that cells grew and proliferated well on the scaffolds.

关键词： bone tissue engineering scaffolds rapid prototyping porous structure

Back analysis of mechanical parameters of roller compacted concrete dam

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Science China(Technological Sciences) 2010年第3期53卷 848-853页

作者： GU ChongShi 1.2,3,LI Bo 1.XU GuangLei 4 &YU Hong 1.2,3 1.State Key Laboratory of Hydrology-Water Resources and Hydraulic engineering,Hohai University,Nanjing 21.098,China 2College of Water Conservancy Hydropower,Hohai University,Nanjing 21.098,China {1. engineering Research Center of Water Resources engineering Safety,Efficient Utilization and Nanjing 21.098,China 4 Nanjing Hydraulic Research Institute,Nanjing 21.029,China 1. State Key Laboratory of Hydrology-Water Resources and Hydraulic engineering Hohai University Nanjing 210098 China2. College of Water Conservancy Hydropower Hohai University Nanjing 210098 China3. National Engineering Research Center of Water Resources Engineering Safety Efficient Utilization and Nanjing Nanjing 210098 China4. Nanjing Hydraulic Research Institute Nanjing 210029 China

In view of the diversity and complexity of mechanical parameters of roller compacted concrete dam(RCCD),the uniform design method,partial least-squares regression(PLS)and least squares support vector machine(LSSVM)were applied to the back analysis of RCCD with the use of the complex nonlinear relationship between dam mechanical parameters and dam *** the process of back analysis,the initial samples of parameters were designed with uniform design ***,a transversely isotropic model of RCCD was established by *** *** this model,training samples of LSSVM model could be *** then,the complex nonlinear relationship between relative values of hydraulic components of dam displacements and mechanical parameters was ***,actual relative values of dam hydraulic components are isolated from the measured data of dam displacements by using *** inputting the isolated relative values into LSSVM model,the back analysis values of RCCD mechanical parameters can be *** example analysis showed that mechanical parameters obtained by the above-mentioned back analysis method are reasonable,and the back analysis method is feasible.

关键词： roller compacted concrete dam mechanical parameters back analysis

Thermal-stress Simulation of Direct-chill Casting of AZ31.Magnesium Alloy Billets

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Journal of Wuhan University of Technology(Materials Science) 2009年第3期24卷 376-382页

作者：胡红军 College of Materials Science and engineering Chongqing University national {1. Research Center for Magnesium Alloys Chongqing University College of Material Science and engineering Chongqing University of Technology

Two-dimensional （2D） transient coupled finite element model was developed to compute the temperature and stress field in cast billets, so as to predict the defects of the I-type billets made from AZ31.magnesium alloy and find the causes and solutions for surface cracks and shrinkages during direct-chill （DC） casting process. Method of equivalent specific heat was used in the heat conduction equation. The boundary and initial conditions used for primary and secondary cooling were elucidated on the basis of the heat transfer during the solidification of the billet. The temperature and the thermal-stress fields were simulated with the thermal-structural coupled module of ANSYS software. The influences of casting parameters on the distributions of temperature and stress were studied, which helped optimize the parameters （at pouring temperature of 680 ℃, casting speed of 2 min/s, heat-transfer coefficient of the second cooling equals to 5 000 W/m^2.℃^-1.. The simulation results of thermal stress and strain fields reveal the formation mechanism of some casting defects, which is favourable for optimizing the casting parameters and obtain high quality billets. Some measures of controlling processes were taken to prevent the defects for direct-chill casting billets.

关键词： magnesium alloy direct-chill casting temperature and stress fields numerical simulation solidification model

Deep-Cut Vacuum Distillation in the 1. Mt/a CDU/VDU

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China Petroleum Processing & Petrochemical Technology 2009年第2期11卷 9-13页

作者： Lin Zhuwei1.Mao Fuzhong1.Jiang Bing2 Chen Kaibei3 Chi Ling3 Yan Chun3(1. KBC Advanced Technologies(Beijing) Co.,Ltd. Beijing 1.0029 2. The national {1. Research Center for Rectification Technology,Tianjin University 3. SINOPEC {1. Incorporation) KBC Advanced Technologies (Beijing) Co. Ltd. Beijing 100029 China national {1. Research Center for Rectification Technology Tianjin University China SINOPEC engineering Incorporation China

This article introduces the concepts relating to deep-cut vacuum distillation and its suitability,and analyzes the deep-cut vacuum distillation technique licensed by the KBC Advanced Technologies to the 1. Mt/a CDU/VDU of the Qingdao refinery and makes comparison on the test run data after commissioning of the distillation unit. The test results have confirmed that the operation of the CDU/VDU had reached the expected goal to achieve good social and economic benefits.

关键词： CDU/VDU deep cut under vacuum distillation rate

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北斗卫星B2信号数字预失真补偿方法研究

系统工程与电子技术 2024年

作者：刘瑞贺成艳张小贞白燕 1.中国科学院国家授时中心 2.中国科学院大学天文与空间科学学院 3.西北工业大学电子信息学院西北工业大学电子信息学院中国科学院大学天文与空间科学学院中国科学院国家授时中心

针对北斗星上信号发射通道中高功放和滤波器引起的导航信号非线性失真问题，本文提出了间接学习结构的数字预失真用以补偿导航信号产生的非线性失真。通过采用带宽最大的非对称恒包络二进制偏移载波（Asymmetric Constant Envelope Bina... 详细信息

针对北斗星上信号发射通道中高功放和滤波器引起的导航信号非线性失真问题，本文提出了间接学习结构的数字预失真用以补偿导航信号产生的非线性失真。通过采用带宽最大的非对称恒包络二进制偏移载波（Asymmetric Constant Envelope Binary Offset Carrier， ACE-BOC）调制的北斗B2信号，验证数字预失真对补偿导航信号非线性失真的有效性及可行性，并从调制星座、功率谱、相关函数以及S曲线过零点偏差等信号评估指标对数字预失真处理前后的信号进行对比分析。实验结果表明数字预失真可以有效抑制20dB的带外功率损失，相关损失可由0.7dB下降到0.009dB以及S曲线过零点偏差由0.88ns下降到0.0029ns。

关键词：北斗卫星导航系统 B2信号高功率放大器数字预失真信号质量评估

Global analysis on slope stability and its engineering application

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Science China(Technological Sciences) 2009年第2期52卷 507-512页

作者： ZHENG Hong1.2 & ZHOU ChuangBing3 1.State Key Laboratory of Geomechanics and Geotechnical engineering, Wuhan 430071. China 2 China Three Gorges University, Key Laboratory of Geological Hazards on Three Gorges Reservoir Area, Ministry of Education, Yi Chang 443002, China 3 School of Civil engineering, Wuhan University, Wuhan 430072, China 1. State Key Laboratory of Geomechanics and Geotechnical engineering Wuhan 430071 China 2. China Three Gorges University Key Laboratory of Geological Hazards on Three Gorges Reservoir Area Ministry of Education Yi Chang 443002 China 3. School of Civil engineering Wuhan University Wuhan 430072 China

In hydraulic engineering, sometimes it is necessary to consider the stability of sliding bodies with lateral frictional boundaries. Neither the existing three dimensional limit equilibrium methods nor the commercial software products are able to treat such situations. The three dimensional factor of safety is accordingly underestimated; while the shearing strength based on the three dimensional back analysis is overestimated. In this study, the lateral boundaries are regarded as the part of the slip surface. Based on the expression of the normal pressure on the slip surface and the patch interpolation, a rigorous solution for the three dimensional limit equilibrium analysis is realized. Meanwhile, the proposed procedure is applied to the stability analysis of the slope with a cable platform on the right bank in Da Gang Shan hydraulic project under construction.

关键词： slope stability the limit equilibrium methods three dimensional problems

Numerical simulation of two-phase turbulent flow in hydraulic and hydropower engineering

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Science China(Technological Sciences) 2007年第z1期50卷 79-89页

作者： DAI HuiChao1.2?, WANG LingLing1. GAO JiZhang3, ZHANG XiaoDong3 & YANG ZhongHua2 1.College of Water Conservancy and Hydropower engineering, Hohai University, Nanjing 21.098, China 2 China Yangtze River Three Gorges Project Development Corporation, Yichang 443002, China 3 China Institute of Water Resources and Hydropower Research, Beijing 1.0044, China College of Water Conservancy and Hydropower engineering Hohai University Nanjing 210098 China China Yangtze River Three Gorges Project Development Corporation Yichang 443002 China China Institute of Water Resources and Hydropower Research Beijing 100044 China

In connection with the specific features of high velocity aerated flow generated by hydraulic engineering structures, the mathematical model is developed for high turbulence air-water two-phase flow with the use of twin flow theoretical model in this paper. Furthermore the numerical method is proposed to treat bubbled flows. In addition, on the basis of air-water stratified twin flow model, the new calculation methods and free surface tracking technique are proposed to describe complicated movements of the free surface. Finally, the proposed model is used to calculate artificial aerated flows. The computed results coincide quite well with experimental results. This means that the proposed method can provide solid basis for practical engineering design.

关键词： high turbulence two-phase flow twin flow model aerated flow free surface

A land surface model incorporated with soil freeze/thaw and its application in GAME/Tibet

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Science China Earth Sciences 2006年第12期49卷 1311-1322页

作者： HU Heping1. YE Baisheng2, ZHOU Yuhua3 & TIAN Fuqiang1.1. Department of Hydraulic engineering, Tsinghua University, Beijing 1.0084, China 2. Cold and Arid Regions Environmental and engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China 3. Department of Civil engineering, Massachusetts Institute of Technology, USA 1. Department of Hydraulic engineering Tsinghua University Beijing 100084 China 2. Cold and Arid Regions Environmental and engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China 3. Department of Civil engineering Massachusetts Institute of Technology USA

Land surface process is of great importance in global climate change, moisture and heat exchange in the interface of the earth and atmosphere, human impacts on the environment and eco- system, etc. Soil freeze/thaw plays an important role in cold land surface processes. In this work the diurnal freeze/thaw effects on energy partition in the context of GAME/Tibet are studied. A sophisti- cated land surface model is developed, the particular aspect of which is its physical consideration of soil freeze/thaw and vapor flux. The simultaneous water and heat transfer soil sub-model not only reflects the water flow from unfrozen zone to frozen fringe in freezing/thawing soil, but also demon- strates the change of moisture and temperature field induced by vapor flux from high temperature zone to low temperature zone, which makes the model applicable for various circumstances. The modified Picard numerical method is employed to help with the water balance and convergence of the numerical scheme. Finally, the model is applied to analyze the diurnal energy and water cycle char- acteristics over the Tibetan Plateau using the Game/Tibet datasets observed in May and July of 1.98. Heat and energy transfer simulation shows that: (i) There exists a negative feedback mechanism between soil freeze/thaw and soil temperature/ground heat flux; (ii) during freezing period all three heat fluxes do not vary apparently, in spite of the fact that the negative soil temperature is higher than that not considering soil freeze; (iii) during thawing period, ground heat flux increases, and sensible heat flux decreases, but latent heat flux does not change much; and (iv) during freezing period, soil temperature decreases, though ground heat flux increases.

关键词： land surface model,soil freeze/thaw,GAME/Tibet,simultaneous liquid,vapor and heat transfer.

Rank of loop, constraint degree of path, coupling degree of graph and their application

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Progress in Natural Science:Materials International 2005年第2期15卷 79-85页

作者： YANG Tingli1., LUO Yufeng2, ZHANG Ce3 and YAO Fanghua1.1. SINOPIC Jinling Petrochemical Corp., Nanjing 21.037, China 2. Department of Mechanical engineering, Nanchang University, Nanchang 330029, China 3. Department of Mechanical engineering, Tianjin University, Tianjin 300072, China) SINOPIC Jinling Petrochemical Corp. Nanjing 210037 China. Department of Mechanical engineering Nanchang University Nanchang 330029 China. Department of Mechanical engineering Tiánjin University Tianjin 300072 China

Some new concepts (rank of a loop, degree of freedom of a graph, path unit and ordered path arrangement, constraint degree of path, coupling degree of a graph, basic graph, etc.), formulas, and algorithms, are proposed in this paper. Based on these concepts, a new systematic theory and practical method for the design of topological structure, kinematics and dynamics of mechanical systems is established. Some conjectures and problems needed to be researched are also put forward. The concepts, formulae and algorithms presented in this paper will find wide potential applications.

关键词： rank of loop degree of freedom of graph constraint degree of path coupling degree of graph