bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Seismic Energy Dissipation Approach to Curved Continuous Girder Bridge
Authors: Qi Xing Jun , Liu Yi , Zhang Chun Hui
Published: September 2011

Under earthquake action there are irregular rotating displacements in the curved girder bridge, and the effective seismic mitigation method for curved bridge need to be systematically studied. The spatial finite element model is established for a curved continuous girder bridge with double-column piers. Energy dissipation dampers including E-steel dampers, viscous dampers, friction pendulum bearings and lead rubber bearings are set in radial and tangent directions of the curve at the positions of active bearings. The seismic mitigation effectiveness and seismic response characteristics of the curved girder bridge are calculated and analyzed with the four energy dissipation approaches under three dimensional ground motion action. The results indicate that the four energy dissipation approaches can all effectively reduce the bending moments and torsional moments at the bottom of piers, and the bending torsion coupling effect of the curved girder bridge is decreased a bit. The difference of internal force for inside and outside piers is reduced after the dampers set for the curved girder bridge with double-column piers. Relatively, the viscous damper approach can further reduce the whole seismic responses of curved continuous girder bridge, and is an excellent seismic mitigation method suitable for curved girder bridge.
Research on Risk Sharing Mode of the Construction Project Based on Systems Theory
Authors: Hu Yun Peng
Published: September 2011

The construction contracts are the important basis of the project risk management and a reasonable contract system can effectively share engineering risks among various project participants. However, the current situation of risk management in China is not optimistic. Based on the analysis of the existing problems in the risk sharing management, the paper introduces Hall three dimension structure into the engineering fields and establishes a three-dimensional (contract dimension, procedure dimension and logic dimension) space structure of the construction project to elaborate the vital role of the contracts in the project risk management. Finally, the paper attempts to put forward a risk sharing mode centered on contract systems to make a reasonable and effective risk distribution among various project participants
The Impact and Potential of Digital Technologies in Buildings
Authors: Nie Zhi Yong , Li Qing
Published: September 2011

Abstract. This article focuses on analyzing the impacts and potentials of digital technologies in buildings by a case study. The results show that digital technologies have deeply involved in many aspects of buildings, such as designing, performance, management and using.
Theoretical Analysis of Bending Capacity of U-Section Steel-Encased Concrete Composite Beams with the Full Connection Design
Authors: Zhou Xue Jun , Zhang Ting
Published: September 2011

The theoretical formula is proposed for cross section’s bending capacity of simply-supported U-section steel-encased concrete composite beams. The result shows that the theoretical formula is in good agreement with the experimental results. This paper concludes that the calculated values based on current steel structure design code of China are very close to the experimental ones. Therefore, this kind of composite beams can be analyzed based on the calculation methods of composite steel and concrete beams in steel structure design code, and it is accurate to calculate the bending capacity based on the assumption of complete shear connection.
Background Response Equivalent Static Wind Load of Large-Span Roofs Based on Energy Equation
Authors: Li Yu Xue , Yang Qing Shan , Tian Yu Ji
Published: September 2011

Based on strain energy equivalent, the background response equivalent static wind load of large span roof is derived. It solves the matter that should consider numerous structural response control objects on calculating equivalent static wind load of large span roofs, and establishes relationship with the structural strain energy introduced by fluctuant wind loads. Finally, the method is used to background equivalent static wind load analysis of China National Stadium roof structure. The results illustrate that the method proposed in this paper is effective and the precision is reliable.
Prediction on Coincidence Effect of Sound Insulation of a Wall
Authors: Huang Xian Feng , Liu Jun , Yang Yan
Published: September 2011

Coincidence effect which occurs in a certain frequency range will impairs the sound insulation of walls. For the purpose to predict the phenomenon of coincidence effect that is unlikely predicted theoretically by the mass law, the Statistical Energy Analysis (SEA) theory are adopted in studying coincidence effect of sound insulation of the light weight single-leaf wall. The comparison among predicted by SEA, by mass law and measured was performed. Therefore, the comparison results show that sound insulation prediction by SEA is more precise and agrees with the measured date. Moreover, the coincidence effect and its effect on sound insulation were predicted by SEA. Eventually, it is likely to select appropriate building materials and configuration to achieve a better sound environment theoretically.
Research on the Safe Lighting of Minor Radius Curve Spiral Tunnels
Authors: Fu Li Xin , Ren Hui , Wang Jian Hua , Zhang Tian Le
Published: September 2011

Abstract: Based on the engineering background of Sichuan Ganhaizi spiral tunnel, this thesis studied the surrounding environment of portal and simulated the whole portal section, and then analyzed the effect of natural light on the portal illumination at different times. With the research on the brightness reduction and human eyes’ adaptation to it, the thesis calculated the discount rate k and obtained the requirements of vehicle speed at Ganhaizi tunnel entrance. Finally, the thesis put forward that some light reduction facilities such as vegetation outside the portal should be used, and on a clear day, from 12:00 to 15:00, the uphill tunnel portal illumination is significantly higher than other sections, thus at this time artificial lighting should be used to modulate entrance lighting.
Study on Failure of Rock Mass around Deep Tunnel
Authors: Qian Yue Hong , Cheng Ting Ting , Cao Xiang Ming , Song Chun Ming
Published: September 2011

During excavating the problem of unloading is a dynamic one essentially. Assuming the unloading ruled by a simple function and based on the Hamilton principal, the distribution of the stress field nearby the tunnel is obtained. The characteristics of the failure nearby the tunnel are analyzed considering the shear failure and tensile failure. The results show that the main mode of the shear failure, intact and tensile failure occurs from the tunnel. The characteristic of the shear failure, intact and tensile failure are one of the likely failure modes.
Study on Preparing Aero-Concrete Using Leaching Residual Slag of Lepidolite Ore
Authors: Huang Shao Wen , Zeng Chuan Lin , Xu Yu Hua , Luo Qi
Published: September 2011

Preparation technology and the performance of aero-concrete using leaching residual slag come from extracting lithium from lepidolite were discussed in this paper. Results show the strength of aero concrete can be slightly improved by using lithium slag instead of fly ash, but the volume density has a major increase, and the gas-forming speed doesn't match the thickening speed. By means of increase in aluminum content and the ratio of water to materials, adding the activating agent, excellent performance products that meet the national standards were synthesized.
Poetic Perception in Built Environment - Anchoring Local Context within Contemporary Architecture
Authors: Kong Ya Wei , Xia Yun , Wang Li Na
Published: September 2011

Based on the relationship of local context and contemporary architecture, perception of body is the key issue to experience in built environment. Through architect Steven Holl’s phenomenological concept and typical work Sifang Contemporary Art Museum, which introduces the perceptual experience of traditional Chinese Garden into international form, this paper explores to anchoring local context within contemporary architecture.
Energy Consumption and Analysis of Air-Conditioning System of Large-Scale Public Buildings in Xi'an
Authors: Pan Wen Yan , Yang Liu , Zhang Zhu Hui
Published: September 2011

As the main consumption equipment, the air-conditioning system of large-sized public buildings in Xi'an consumes 30%~¬60% of the total energy. Combining with the survey data and related norms, the paper analyses the energy consumption from the following aspects: basic situation of building, index of building energy consumption, ratio of energy consumption of air-conditioning system, load of air-conditioning and indoor environment. Thus, it will give a rational and scientific understanding to energy-efficiency of air-conditioning system of large-scale public buildings in Xi'an for the purpose of providing an efficient assistance to improving the energy consumption of air-conditioning system.
Study on the Reinforce Scheme to a Karst Slope of Shuinan Highway
Authors: Zhu Wen Xin , Ding Wan Tao
Published: September 2011

There is potential main landslip and thin-layer siliceous rock undisturbed at the lower part of the left side of Karst slop K133＋180. During the course of excavation, due to the effect of gravity, creep and ulcerate flexion slip surface might occur. From the slope geo-mechanics model perspective, this paper proposes two reinforce schemes on the slope based on the slope reinforce project experiences on the slope of similar condition in the area after taking into account the effect of rainfall conditions. The paper also compares the economic efficiency of the two schemes and considers that, provided that the slope design is stable, scheme 2 shall be more economically efficient. As a conclusion, the left slop K133＋180 was reinforced with scheme 2. So far, the slope keeps stable and firm through times of rainfall. The reinforce experience on the Karst slope K133+180 shall be able to act as a useful reference for similar projects.
The Application of Ore Surface Model in Computer State Delineating Method
Authors: Zhao Yu Yin , Bai Ping , Liu Xin Hua
Published: September 2011

Traditionally, the computer method of delineation requires to establish ore block model. The block-by-section scanning operation is slow, which does not meet the large amount of data calculation., In this paper, we use the ore body in the modeling of the surface model in order to overcome the above problem. This model uses modeling method that reproduces a traditional hand-paintedtechnique, describe the spatial distribution of ore bodies through a series of plan view or profile of the ore body boundary polygon for wireframe modeling, i.e., the frame modeling method. For reading the plan view or profile of the ore body, the graphics and fractal theory are needed in the work to achieve the extraction of vector graphics map elements. After completing the extraction of ore, the wireframe modeling of the ore bodies can be established by using wireframe modeling method. Finally the wireframe model is filled by using the OpenGL technology and the surface model orebody is generated.
The Study on Adaptive Design of Mountainous Old Campus Space Renovation - A Case Study on Chongqing University
Authors: Zuo Jin , He Xiao Li
Published: September 2011

Since the beginning of the 21st century, large-scale extensive expansion of suburb new campus construction has been a kind of abnormal phenomenon in the process of the rapid development of modern higher education. Along with the implementation of land macro-control policies, the old campus space renovation will be the significant direction in campus construction. The complex natural environment and more limited land resources are key factors in mountainous old campus space renovation. Taking Chongqing University as the example, the paper analyzes the relationship of symbiosis, coexistence, mutual prosperity between mankind and the elements in particular mountainous environment. Starting from the whole and harmony, we try to discuss the adaption of mountainous old campus to natural environment, built environment and cultural environment by adopting adaptive methods, so as to maintain its regional character, and guide mountainous campus construction to overcome the environmental bottle-neck. Based on own advantages, the mountainous old campus will develop to be a high efficient, compact and open ecological adaptive campus by continuous effective renovation.
Study on the Vertical Design of Urban Underground Complex Pipeline
Authors: Wang Qiu Ping , Bai Yang , Zhang Qi , Wang Lei Juan , Liu Ting Ting
Published: September 2011

There are many problems caused by the unreasonable vertical pipeline planning and design in urban underground pipeline projects. This paper centers on improving the level of the vertical planning of complex pipeline, and identifying the reasonable design sequence of complex pipeline on the Blin method which using the principle of fuzzy mathematics. According to the existing method of vertical pipeline design, a model of vertical crossing of various single pipelines in urban intersection is established. Meanwhile, a new method of the vertical planning and design of complex pipeline is put forward. A case design of complex pipeline is carried out with this method to verify the feasibility as well as the effectiveness of it, hoping to provide design ideas for majors in the vertical planning and design of complex pipeline.
Research on Conservation Planning Method of Lingnan Ancient Villages
Authors: Su Ping
Published: September 2011

From the case study of Nanwan village which is one of the typical samples of Lingnan ancient villages in Guangzhou, the article summarize the features of physical morphology and social morphology in Lingnan ancient villages and analyses the meaning and problem within. Based on the planning practice, it also puts forward several conservation planning methods for physical morphology reestablishment and social morphology reestablishment of Lingnan ancient villages.
Study on Regional Cultural Landscape Classification of Kunming’s Leisure Agricultural Garden
Authors: Liu Hong Lin
Published: September 2011

Through investigating the characteristic of regional cultural landscape of leisure agricultural garden around Kunming city, seven landscape types are proposed including rural agriculture landscape, folk customs landscape, village and township landscape, leisure resort landscape, returning to nature landscape. The regional cultural landscapes are analyzed in depth and breadth. The results can provide design ideas for building leisure agricultural garden having regional culture characteristic.
On Commonality and Particularity of Urban Pattern Features
Authors: Jin Nai Ling
Published: September 2011

The Urban spatial pattern is an important characteristic of a city. In this article, the burning social problem of urban identity crisis is discussed, and then, the features of urban pattern are explored according to relationship between commonalities and particularities of urban pattern in Chinese feudalism, and access path of modern urban pattern features are expounded, i.e. the urban pattern features are remodeled by the city’s commonality as the background and its particularity as a bright spot.
Low Carbon-Oriented Methords for Urban Plan Based on Ecological Technologies
Authors: Guo Hai Bo , Fan Xin Yu
Published: September 2011

It was the research on spatial pattern that received most attention in traditional theories of urban plan. The majority of city practical consequences were expressed in the form of illustration by qualitative analysis, and lack of data supporting by quantitative analysis. The authors study this research by the methods of calculating the relevant datum and comparative analysis; introduce ecological rationales into the urban plan, and put forward three quantitative strategies: First, the authors investigate the coupling relationship between the city spatial pattern and carbon emissions by “Ecological Footprint” and clarify how some typical city spatial patterns effect carbon emissions; Second the authors designate the ecological sensitive area by GIS, establish the city carbon sink system, identify the landscape structure; At last, in order to modulate and optimize the industry distribution, the authors hunt for the limiting factors which restrict the development of industry by “Bottleneck Index”. In responds to this situation, introducing ecological and low carbon technologies into the urban plan may open up a new orientation to provide the theoretical references. Furthermore, some obscure intensions put forward by experience can be translated into digital technical specification which is available for practical operation.
Experimental Study on Thermal Insulation Properties of Reinforced Concrete Composite Wall
Authors: Zhao Shun Bo , Yang Su , Song Li Sha , Sun Li , Song Chen Xiao
Published: September 2011

The paper briefly introduces the form and construction method of a new reinforced concrete composite wall (RCCW) with inner insulating layer of polystyrene panel. The thermal insulation properties such as heat resistance, heat exchange resistance and heat transfer coefficient of the RCCW were measured by the protection chest method, six specimens in dimensions of 1450mm×1450mm×300mm were cast with the same thickness of prototype walls of building envelop, three kinds of linkages of the RCCW were considered, and two surfaces of the specimen were tested respectively as the heat bearing surface to simulated different heat resources. Based on the tests, the effects of linkages and heat resources on thermal insulation properties of the RCCW are analyzed, some improvements are proposed for reducing the heat-bridge effects as much as possible.
The Dynamic Characteristic of Gear Pump-Motor Unity Machine
Authors: Zhang Jun , Lu Shu Qun , Yuan Yuan
Published: September 2011

The gear pump-motor unity machine, which was composed of the planetary gear pump and multiple gear variable-displacement motor was designed by the author. In this paper, based on the physical model, mathematical models of the machine were established. The transfer functions were deduced and the block diagrams of the transfer functions were drawn. The dynamic characteristics of the machine were analyzed. While the damping coefficient is rising, the oscillation amplitude will decrease. While the damping coefficient is bigger, both overshoot fluctuation are smaller. While the steady-state adjusting time is decreasing, dynamic response characteristics of the motor significantly improved. While the leakage coefficient is rising, the response speed of motor will improve, but the excessive leakage coefficient increases will lead to larger leakage, which seriously impact the motor performance. The dynamic characteristics of the machine were analyzed. As of ωn>0 and ξ>0, gear-pump motor unity machine is inevitably stable.
Study on Static Strength of Circular Hollow Section (CHS) T-Joint Reinforced with FRP
Authors: Chen Cheng , Shao Yong Bo , Yang Jie
Published: September 2011

The static strength of circular hollow section (CHS) T-joint reinforced with FRP (Fiber Reinforced Polymer) is studied through the experimental test and finite element simulation. Based on the reliability of the finite element simulation which is verified from experimental data, the parametric analysis is conducted by using finite element (FE) software ABAQUS. In the parametric analysis, the improvement of FRP with different bonding lengths, directions and layers on the static strength of tubular T-joints is considered. Simultaneously, the effect of two key geometrical parameters  and  of the tubular joints on the reinforced efficiency is also included. Based on the results of the parametric study, the effect of FRP on increasing the static strength of tubular joints is finally generalized.
The Damage Model of Concrete under Coupling Action of Calcium Leaching and Load
Authors: Liu Qiao Ling , Zhang Xu , Xu Li Na , Jia Li Qun
Published: September 2011

For calcium leaching and loaded concrete in engineering structures, defining the initial damage state as basic state, the damage model of calcium leaching and loaded concrete is established using damage mechanical theory and principle of strain equality. It is shown that the mechanical properties of calcium leaching and loaded concrete are determined by calcium leaching, load and coupling effect. For calcium leaching and loaded concrete, the influence factors to stress at any point are elastic modulus, maximum strain, strain at this point and the degree of calcium leaching.
Influence of Stone Dust Content in Manufactured Sand on Chloride Diffusion Coefficient of C60 Grade Concrete
Authors: Li Peng Ping , Xiong Jian Bo , Fan Zhi Hong
Published: September 2011

The influence of stone dust content on chloride diffusion coefficient in C60 grade concrete were investigated by means of the natural immersion test, XRD test, MIP test and TGA test, respectively. The experimental results showed that the chloride diffusion coefficient increased with increasing the stone dust content in manufactured sand, and the chloride diffusion coefficient increased little when the stone dust content increasing from 7% to 13%. The hydration degree for cementitious and compressive strength for concrete was slightly promoted by using stone dust replacing cementitious at a low level. But the porosity and average pore size of concrete increased with increasing the stone dust content from 3% to 13%, and the concrete pore structure was the main factor that influences the changes of chloride diffusion coefficient in concrete.
Difference Solution to Chloride Diffusion in Concrete
Authors: Yu Ai Ping , Lu Hai Bo , Zhao Yan Lin , Wei Ke Yu
Published: September 2011

Fick’s second law and its analytical solution were usually used for analysis of chloride diffusion in concrete. But discretization of the continuous variables is more appropriate in modeling and discrete model is more suitable for engineering applications. In this paper, Difference Equation equivalent to partial differential equation was established with the difference method, and three-dimensional differential equation of Fick's second law was resolved. Based on this study，the convergence conditions of difference Equations for one-dimensional, 2D and 3D diffusion was given.
Studies on Influence of Mineral Admixtures on High Performance Concrete Gas Permeability
Authors: Zhang Xian Tang , Gao Kang Ning , Zhou Xiao Chen , Wang Hong Li
Published: September 2011

There is a close relationship between the gas permeability of modern high strength concrete and the concrete durability. Through the Cembureau method, gas permeability coefficients of ordinary concrete and concrete with admixtures under different maintenance periods were tested. We studied the influence of fly ash and slag on high performance concrete gas permeability, and analysed the rules of gas permeability changing with mineral admixtures and the water-binder ratio, and gave the reasonable range of mineral admixtures and the water-binder ratio. The results from the paper may have the certain reference value to practical application.
Experimental Study on Cementitious Property of Pumice
Authors: Liu Jing , Lv Xing Jun , Cao Ming Li , Cui Shi Cai
Published: September 2011

Because of its poor pozzolan property in tests, the pumice was unsuitable to be used as the cement admixture, which could reduce the compressive strength greatly. In the experiment, the cement，replaced with several ratios of pumice，was stimulated by the different content of mixed solution with sodium silicate and KF. The compressive strength results and the SEM morphologies showed that mixed solutions can display excellent alkali-activated effects on pumice.
The Dynamic Mechanical Constitutive Equation of Concrete under High Temperture
Authors: Jia Bin , Li Zheng Liang , Tao Jun Lin , Zhang Chun Tao
Published: September 2011

Based on the test by the split Hopkinson Pressure Bar (SHPB), in this papaer the research on the dynamic mechanical properties of concrete under high temperture has been conducted, the influence law of temperature and strain rate on the mechanical peoperties has been analyzed, and the dynamic stress-strain curves of concrete under high temperature have been obtained. Analysis indicate that the concrete strain rate hardening effect is coupled with the high temperature weakening effect. Therefore, on the basis of classical damage theoretical model, in accordance with the concrete high-temperature dynamic mechanical characteristics, a unified equation is established to describe the whole process of concrete dynamic stress-strain relationship under high temperature, which is well coincided with the test results.
Numerical Study on Tunnel Mechanics in Jointed Rock Mass with Finite Element Method
Authors: Zhang Ming Gao , Wu Heng Bin , He Ze Ping , Zhou Ting Qiang
Published: September 2011

Tunnel mechanics mainly depend on joints properties in layered and jointed rock mass, and most of the present methods adopted in numerical analysis are distinct element method. Combining to the Gaixiaba tunnel, considering the jointed properties such as dip angles, distances and lateral pressure coefficient, the finite element models are made in this paper. Results show that the plastic zone and total displacement presented a symmetric distribution with the axial of joints dip, and the plastic zone is very similar to the results suggested by Goodman. The dip angles, distances of joints and lateral pressure coefficient have significant effect on the tunnel mechanics.
A New High Temperature Resistant Glass–Ceramic Coating Material
Authors: Chen Xiang Tian , Han Ye , Yao Shu Yu , Zhang Wei Wei , Yao Yun Sui , Wang Zong Feng
Published: September 2011

A new glass-ceramic coating material on nickel based super alloy substrate had been found, the glass¬-ceramic coating material was developed from a glass based on MgO–Al2O3–TiO2 system. The coating material was characterized through X-ray diffractometry (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), hardness, thermal expansion coefficient testing. XRD analysis of the coating materials and the resultant coatings showed presence of a number of microcrystalline phases. SEM micrographs indicated microstructure of the material. Optical micrographs showed smooth glossy impervious free surface with defects. Hardness analysis showed the glass-ceramic coating material had higher microhardness. The thermal expansion coefficient of the nimonic alloy was much higher compared to the coating material at specific temperature.
The Properties of Concrete with Recycled Clay-Brick-Powder
Authors: Zheng Li , Ge Zhi , Yao Zhan Yong , Sun Ren Juan , Dong Jun Gui
Published: September 2011

This paper studied the splitting tensile strength of concrete containing partial clay-brick-powder. Four variables, water to cementitious material ratio (W/CM), sand ratio, cement replacement ratio, and the average particle size of clay-brick-powder were determined to analyze the affected factors on the properties of the concrete. The orthogonal experimental design table L16 (45) was adopted to study the significance sequence of the variables. Total 17 type mixes, including one normal cement concrete as reference, were tested. Experiment results showed that recycled clay-brick-powder could be used as partial replacement of cement in concrete. The splitting tensile strength of samples with clay-brick-powder ranged from 2 to 4MPa.
Research on Dynamic Instability of Irregularly-Shaped Arch Bridge Based on Catastrophe Theory
Authors: Yang Xiao Rong , Shen Xue Jing , Zhong Min , Lan Jiao Xia
Published: September 2011

According to the characteristic of poor stiffness of V-shaped beams, transverse dynamic instability model of V-shaped is presented by Catastrophe Theory. Mechanism of stability of V-shaped is analyzed. Coordinates of two cusps and instable bifurcation set is derived. Effect of nonlinear coefficient and frequency ratio on amplitude of V-shaped beams are analyzed. When nonlinear coefficient is , continuous change of can arise abrupt change of amplitude. Then the jumping phenomenon can leads destruction of V-shaped beams.
Improve Journal Bearing Design Using Numerical Method
Authors: Jiang Neng Jun , Peng Ya Ling , Wu Fang Liang
Published: September 2011

Computational Fluid Dynamics (CFD) was used to study the force direction and magnitude of 2D journal bearing and tapered gap, also the load of 3D journal bearing at different eccentric ratio was studied using numerical method. All numerical simulation results were compared with theoretical analysis result, theoretical solution result and other available data from reference. The comparisons show good match between numerical simulation results and others. This paper had validated the reliability and accuracy of CFD which could be used to study the lubrication and oil film status for journal bearing with the gap less than 0.2mm and provide a sold foundation for CFD to be used for optimal design for journal bearing.
Finite Element Analysis of Stress Concentration Problems Based on Cosserat Continuum Model
Authors: Tang Hong Xiang , Guan Yu Hui
Published: September 2011

In the present work, the Cosserat micro-polar continuum theory is introduced into the FEM numerical model, which is used to simulate the stress concentration problems. The stress concentration phenomena around circular hole, elliptic hole and rhombic hole in plane strain condition, are numerically simulated by two types of Cosserat continuum finite elements of the standard displacement and rotation u4ω4 and u8ω8 based on Dirichlet principle. It is indicated that, compared with the classical continuum finite element, these two Cosserat continuum finite elements can reflect the steep strain gradient and scale effects occurring in the stress concentration problems, and they can weaken the stress concentration and may get consistent solution with actual situation.
Research on the Relation between the Mechanical Parameter and Water Content about the Synthetic Geotechnical Simulation Material
Authors: Liu Chang Wu , Liu Shu Xin , Xu Yu Hang
Published: September 2011

The physical simulation test of similar material is one of the most common research techniques in the geotechnical domain. Because the experimental finding of physical simulation is directly affected by the physical mechanical property and stability of similar material, then selecting the fitting formulation, mixture ration and water content of the similar material for different investigated subjects to get the ideal similar material is the most attentive problem during the experiment. After researching the variational compressive strength and tensile strength with the water content of the synthetic material which is made of sand, cement, gesso with two mixed rations, the relation of second-degree parabola between the main mechanical parameter and the water content of the synthetic material is obtained, and the optimal rate of water content which can make the similar material reach the maximal compressive strength or tensile strength is obtained
Preparation and Humidity Controlling Behaviors of Diatomite/Polyacrylic Acid Composite
Authors: Wang Ji Hui , Ren Shu Ping , Zhang Meng Long , Dong Fei
Published: September 2011

Diatomite/polyacrylic acid composite was synthesized by using inverse suspending polymerization method under different diatomite content, dispersant content and neutralization degree with orthogonal experiments. The surface morphology, structure and humidity controlling properties of composite were observed and determined. The results show that diatomite/polyacrylic acid composite is in a block like structure with different size. During the polymerization process, acrylate monomer is grafted with hydroxyl on the surface of diatomite and then inserted successfully into the void of diatomite. The impact of three factors on the humidity controlling behavior of composites increases by the order of dispersant content, neutralization degree and diatomite content. The optimum preparation parameters are diatomite content of 40%, dispersant content of 15%, neutralization degree of 90%.
Improved Endothelialisation on Nanostructured Surfaces
Authors: Aktas Cenk , Haidar Ayman , Martinez Miró Marina , Dörrschuck Eva , Lee Juseok , Veith Michael , Abdul Khaliq Hashim
Published: September 2011

Abstract . Topography plays a major role on surface-cell interaction beside the surface chemistry. We investigated the effect of the nanotopography on vascular cell adhesion and proliferation in order to improve endothelialisation for restenosis treatment. In this context, Al2O3 nanowires (NWs) composed of a stable Al2O3 shell and an Al core were synthesized by chemical vapour deposition (CVD) of the molecular precursor (tBuOAlH2)2. After the detailed material characterization, human umbilical vein endothelial cells (HUVEC) and human umbilical vein smooth muscle cells (HUVSMC) were seeded and cultivated on these surfaces. Our preliminary results showed that there is a preference of HUVEC adhesion on NWs in comparison to that of HUVSMC. The control of the cell–surface interaction by the topography may represent a key issue for the future stent material design.
Oxygen-Induced Formation of Nanopyramids on W(111)
Authors: El-Jawad Mohammad , Gilles Bruno , Maillard Frederic
Published: September 2011

In this study, we investigated the role of oxygen in the faceting of the W(111) surface at temperatures close to T = 2000°C. For that purpose, we characterized the W(111) surface before and after the annealing step by low energy electron diffraction (LEED), reflection high energy electron diffraction (RHEED), scanning tunneling microscopy (STM), and Auger electron spectroscopy (AES). It is found that W(111) undergoes a massive reconstruction to form three sided pyramids of nanometer dimensions with mainly {211} planes as facet sides. Interestingly, the facetted W(111) surface is deprived from oxygen. We then show how the facetted W(111) surface can be used as a template to deposit platinum by molecular beam epitaxy.
Promoting Effect of CeO2 Addition on Activity and Catalytic Stability in Steam Reforming of Methane over Ni/Al2O3
Authors: Rakib Abdelmajid , Gennequin Cédric , Dhainaut Thierry , Ringot Sylvain , Aboukaïs Antoine , Abi-Aad Edmond
Published: September 2011

Hydrogen production by steam reforming of methane was studied over Ni catalysts supported on CeO2, Al2O3 and CeO2-Al2O3. These catalysts were prepared using the impregnation method and characterized by XRD. The effect of CeO2 promoter on the catalytic performance of Ni/Al2O3 catalyst for methane steam reforming reaction was investigated. In fact, CeO2 had a positive effect on the catalytic activity in this reaction. Experimental results demonstrated that Ni/CeO2-Al2O3 catalyst showed excellent catalytic activity and high reaction performance. In addition, the effects of reaction temperature and metal content on the conversion of CH4 and H2/CO ratio were also investigated. Results indicated that CH4 conversion increased significantly with the increase of the reaction temperature and metal content.
Effect of the Residual Deformation on the Mechanical Behavior of the Ni-Ti Alloy Charged by Hydrogen
Authors: Gamaoun Fehmi , Skhiri Imen , Bouraoui Tarak
Published: September 2011

Because of its good corrosion resistance and biocompatibility, superelastic Ni-Ti wire alloys have been successfully used in orthodontic clinics. However, delayed fracture in the oral cavity has been observed. The susceptibility of a Ni–Ti shape memory alloy towards hydrogen embrittlement has been examined with respect to the residual stress after a few numbers of cycles and ageing in air at room temperature. Orthodontic wires have been cathodically charged by hydrogen with a current density of 10 A/m2 from 4h in 0.9% NaCl aqueous solution at room temperature. The critical stress for the martensite transformation under a monotonous tensile test of the as-charged specimen has been 30 MPa higher than that without hydrogen charging. However, after 1 to 50 cycles followed by hydrogen charging, the austenite-martensite plateau is decreased outstandingly compared to the monotonous tensile test of the as-charged by hydrogen specimen. Moreover, compared to the non-cycled and hydrogen charged material, the cyclic deformed and charged by hydrogen specimens present an increase of the initial stress for inducing martensite structure. This increase is about 110 MPa after 50 cycles. In addition, an embrittlement has been detected for the specimen submitted to 50 cycles and hydrogen charging for 4h. This behavior is attributed to the generated dislocations during cyclic deformation which act as trapping sites of hydrogen and a barrier for the austenite-martensite transformation.
Fatigue Behavior of α/β Brass
Authors: Fardoun Farouk , Iyengar S. , Melin Solveig
Published: September 2011

Brass is a popular engineering material used in a variety of applications requiring good strength, ductility, corrosion resistance and machinability. This work focuses on the analysis of Stress – Strain Hysteresis Loops obtained in low cycle fatigue experiments in order to determine the internal and effective components of the stress amplitude which provide valuable information about damage mechanisms. Cyclic plastic straining has been studied using the SAP method (Statistical Approach of Plastic deformation). This approach allows the evaluation of the effective and internal stresses, effective elastic modulus and the probability density function, f(σic), which reflects the microstructure of the plastically deformed material. f(σic) obtained from each reversal exhibits two peaks in α/β brass, corresponding to the plastic deformation of each component phase of this material. At low strain amplitudes and during the initial loading cycles, a single peak has been generally observed. However, at high strain amplitudes and at the stabilization stage of the hysteresis loop, two distinct peaks could be distinguished. Further, relative to the effective stress, the internal stress shows a hardening effect with strain amplitude.
From Nanoparticles to Process: An Aberration-Corrected TEM Study of Fischer-Tropsch Catalysts at Various Steps of the Process
Authors: Braidy Nadi , Andrei Carmen , Blanchard Jasmin , Abatzoglou Nicolas
Published: September 2011

χThe nanostructure of Fischer-Tropsch (FT) Fe carbides are investigated using aberration-corrected high-resolution transmission electron microscopy (TEM). The plasma-generated Fe carbides are analyzed just after synthesis, following reduction via a H2 treatment step and once used as FT catalyst and deactivated. The as-produced nanoparticles (NPs) are seen to be abundantly covered with graphitic and amorphous carbon. Using the extended information limit from the spherical aberration-corrected TEM, the NPs could be indexed as a mixture of NPs in the θ-Fe3C and χ–Fe5C2 phases. The reduction treatment exposed the NPs by removing most of the carbonaceous speSubscript textcies while retaining the χ–Fe5C2. Fe-carbides NPs submitted to conditions typical to FT synthesis develop a Fe3O4 shell which eventually consumes the NPs up to a point where 3-4 nm residual carbide is left at the center of the particle. Subscript textVarious mechanisms explaining the formation of such a microstructure are discussed.
TEM Investigation of Horizontal-Grown Silicon Nanowires
Authors: Abu-Safe Husam
Published: September 2011

Horizontal silicon nanowires were grown using thermal annealing of thin layers of aluminum on silicon substrates. The template to grow these wires was the thin aluminum layer. As the samples reached the eutectic temperature during annealing, silicon dissolved rapidly in the aluminum layer and deposited at the grain boundary in a form of silicon nanowires. Cross sectional TEM analysis indicated the crystalline structure of these wires.
Quantitative Evaluation of Strain in Epitaxial 2H-AlN Layers
Authors: Nader Richard , Pezoldt Joerg
Published: September 2011

To improve the quality of AlN layer deposit on SiC/Si, different Ge amounts (0.25, 0.5, 1, 2ML) were deposited before the carbonization process at the silicon substrate in order to reduce the lattice parameters mismatch between Si and SiC grown layers. The residual stress of the hexagonal AlN layers derives from the phonon frequency shifts of the E1(TO) phonon mode. The crystalline quality of the AlN layer is correlated to and investigated by the full width of the half maximum (FWHM) and the intensity of E1(TO) mode of the 2H-AlN. Best crystalline quality and lower stress value are found in the case where 1ML of Ge amount is predeposited. The E1(TO) mode phonon frequency shifts-down by 3 cm-1/GPa with respect to an unstrained layer.
Defect Interactions and Polytype Transitions
Authors: Pezoldt Jörg , Kalnin Andrei Alexandrovich
Published: September 2011

The polytype transitions are caused by disorder generation in the initial structure due to energy dissipation. The disorder is strongly related to the formation and propagation of stacking faults and partial dislocations. Collective and selective interactions between these defects result in a stability loss of the original structure leading to nonequilibrium phase transition occur if the critical point is reached. The stability of the defect subsystem was investigated in the stationary state for three types of stacking faults. The combination of the stability analysis with the defect generation processes during the different technological and devices operation processes allows predicting the critical values for the external forces and fluxes leading to phase transitions.
Characterization of Nitrided Gate Oxide Formed by RTP for SiC MOSFET Application
Authors: Constant Aurore , Godignon Philippe
Published: September 2011

Gate oxides for SiC lateral MOSFETs have been formed in N2O by rapid thermal processing (RTP) as an alternative to the conventional furnace process. This innovative oxidation method has not only the advantage to significantly reduce the thermal budget compared to a standard oxidation, but also to produce oxide layers with quality comparable to the one grown in a conventional furnace. Moreover, a significant improvement of the oxide quality and MOSFET performance is observed when performing in-situ a H2 anneal prior to oxidation as surface pretreatment. The channel mobility and the breakdown field of the gate oxide are considerably increased.
Suitable Characterization Methods and Insulating Materials for Devices Operating above 200 °C
Authors: Locatelli Marie Laure , Diaham Sombel , Valdez-Nava Zarel , Bechara Mireille , Khazaka Rabih
Published: September 2011

Two characterization techniques, the steady-state Conduction Current (CC) and the low frequency Dielectric Spectroscopy (DS) are reviewed and compared to each other in order to choose the most suitable method for evaluating the static electrical conductivity (σDC) of an insulating material. In the case of polymeric materials operating above 200°C, the DS appears as being better suited. These techniques are applied for insulating materials identified as good candidates for high temperature (HT) applications and new results are presented. HT polyimide, parylene films and silicon nitride substrates are studied. These examples highlight the σDC magnitudes for temperatures up to 400 °C, as well as other relevant parameters to be taken into account for practical applications.
Annealing Effects on Electrical and Optical Properties of N-ZnO/P-Si Heterojunction Diodes
Authors: Faraz Sadia Muniza , Alvi Muhammed Naveed , Henry Anne , Nour Omer , Willander Magnus , Wahab Qamar Ul
Published: September 2011

The effects of post fabrication annealing on the electrical characteristics of n-ZnO/p-Si heterostructure are studied. The nanorods of ZnO are grown by aqueous chemical growth (ACG) technique on p-Si substrate and ohmic contacts of Al/Pt and Al are made on ZnO and Si. The devices are annealed at 400 and 600 °C in air, oxygen and nitrogen ambient. The characteristics are studied by photoluminescence (PL), current–voltage (I-V) and capacitance - voltage (C-V) measurements. PL spectra indicated higher ultraviolet (UV) to visible emission ratio with a strong peak of near band edge emission (NBE) centered from 375-380 nm and very weak broad deep-level emissions (DLE) centered from 510-580 nm. All diodes show typical non linear rectifying behavior as characterized by I-V measurements. The results indicated that annealing in air and oxygen resulted in better electrical characteristics with a decrease in the reverse current.
Calculation of Electronic and Optical Properties of Zinc-Blende MGX ZN1-X S
Authors: Mostefai Nadjla , Bouarissa Nadir , Belkhir Abdelhak
Published: September 2011

The electronic and optical properties of the MgxZn1-xS semiconductor ternary alloys crystallizing in the Zinc Blende structure are calculated using the empirical pseudopotential method (EPM) coupled with the virtual crystal approximation (VCA). The composition dependence of the direct and indirect band gap energies as well as the antisymmetric gap are investigated in the composition range 0 up to 1. Other quantities such as refractive index and coefficient of reflection are also obtained by means of different existing models. Our results are generally in good agreement with those available in the literature. The obtained informations could be useful for the feature design of blue wavelength optoelectronic devices.
Nanoporous Solids: Materials for a Sustainable Development
Authors: Patarin Joël
Published: September 2011

Nanoporous solids characterized by a narrow pore size distribution such as zeolites (aluminosilicates) and related materials (other silica-based materials, phosphate-based materials,...) have a large range of application. These solids and in particular the pure silica zeolites (named zeosils) which display a non-charged framework are very promising solids for the trapping of air pollutants (odors, VOCs,...) but also, thanks to their strong hydrophobic character, they can be used in the field of energetics. After some generalities on these solids, this latter application is illustrated by few examples.
Modeling of the Boron Emitter Formation Process from BCl3 Diffusion for N-Type Silicon Solar Cells Processing
Authors: Armand Jimmy , Oliver Cyril , Martinez F. , Semmache B. , Gauthier M. , Foucaran Alain , Cuminal Yvan
Published: September 2011

This work is devoted to the study of boron doping diffusion process for n-type silicon solar cells applications. Deposition temperature is an important parameter in the diffusion process. In this paper we investigate its influence using an industrial scale furnace [1] (LYDOPTM Boron), which is developed by Semco Engineering. We especially used a numerical model (Sentaurus) in order to further understand the boron diffusion mechanism mainly with respect of the diffusion temperature. The model calibration is based on boron concentration profiles obtained by SIMS (Secondary Ion Mass Spectrometry) analysis. We observed that the boron profiles could be correctly simulated by a single fitting parameter. This parameter, noted kBoron which is connected to the chemical reaction kinetics developed at the interface between the boron silicon glass (BSG) and the silicon substrate