bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on Manipulator Positioning Based on Stereo Vision in Virtual Environment
Authors: Zou Xiang Jun , Zou Hai Xin , Lu J. , Chen Yan , Guo Ai Xia , Deng J.Z. , Luo Lu Feng
Published: March 2009

Inherent uncertainties always exist in the positioning picking manipulators in complex environment, modeling and simulation of positioning. The manipulators were discussed based on binocular stereo vision in virtual environment (VE). Based on stereo vision, a method how virtual manipulators locate picking object by human-computer interaction (HCI) was proposed. The data input from vision were mapped to virtual picking manipulators so that it could enable the positioning and simulation with route and events-driven mechanism. The positioning experimental platform in VE consists of hardware of CCD stereo vision and simulation software. The visualized simulation system was exploited by EON SDK. The simulation of manipulator’s positioning was realized in VE by the platform. This method can be used for virtual robot to locate objects’ long-distance positioning in complex environment.
Research on the Relationship between Indenter Tip Radius and Hardness with a Self-Designed Nanohardness Test Device
Authors: Liu Qiang , Yao Ying Xue , Zhou L.
Published: March 2009

Nanoindentation device has the ability to make the load-displacement measurement with
sub-nanometer indentation depth sensitivity, and the nanohardness of the material can be achieved
by the load-displacement curve. Aiming at the influence law of indenter tip radius to indentation
hardness, testing on the hardness of single-crystal silicon were carried out with the new
self-designed nanohardness test device based on nanoindentation technique. Two kinds of
Berkovich indenter with radius 40nm and 60nm separately were used in this experiment. According
to the load-depth curve, the hardness of single-crystal silicon was achieved by Oliver-Pharr method.
Experimental results are presented which show that indenter tip radius do influence the hardness,
the hardness value increases and the indentation size effect (ISE) becomes obvious with the
increasing of tip radius under same indentation depth.
The Study on the Key Technology of Turbine Blade CNC Belt Grinding Machine
Authors: Wang L.T. , Zhang F. , Qian W.M. , Ji Y.Y. , Li Y.
Published: March 2009

According to the structure features of turbine blade, the analysis of the grinding motion
has been done and, based on the restriction conditions, the structural configuration of belt grinding
machine has been described. Then the configuration of the control axis of belt grinding motion and
the machine tool structure has been determined. The kinematics model of the blade grinding has
been built by the motion control chain of the machine tool. The tool path algorithm of belt grinding
has been proposed with STL 3D data model of blade surface. Based on IPC and Programmable
Multi-Axis Controller PMAC, the CNC system of turbine blade belt grinding machine has been
designed. Finally, the prototype of Turbine Blade CNC Belt Grinding Machine has been made.
Research on the Method of Client Customization Design
Authors: Hu Qing Xi , Luo X.J. , You Fei , Lu Qi
Published: March 2009

A modular design idea oriented to client customization is proposed to achieve product
diversification and personalization. The Key technology of customized design is studied to meet the
market's requirement of short cycle, high quality and low cost in product design and manufacturing.
In the detailed design stage, the method of Top Basic Skeleton (TBS) is applied, which improves
the rapid response ability of product design and shortens the product development cycle. On this
base, a rapid design method of customized vacuum casting machine is illuminated. In the dynamic
and changing market environment, the rapid design method plays an important role in improving
the competitive power of enterprise.
Research on Simulation of Rotary Burrs NC Grinding
Authors: Zhang Guan Wei , Zhang S.C. , Lin Yu Tian
Published: March 2009

A 3D rotary burrs grinding simulation system is described. By analyzing the structure of
rotary burrs 4-axis NC grinding machine tool, rotary burrs grinding motion model is established. The
method of axis direction decomposition based on 3D modeling is provided, which includes
decomposing rotational part into simple primitive cells by using Visual C++ and OpenGL as the
developing tools, and implementing the boolean operation between the part model and a tool
sweeping solid dependent on the tool shape and tool trajectory for each tool movement. To use
grinding machining simulation analysis of the interference resulted in grinding, main factors range is
determined. Security region is identified in order to avoid interference between grinding wheel and
the tooth surface, which can be used for guiding production of rotary burrs and improving the quality
of grinding.
Preparations and Properties of Solid Lubricants Coating on High-Speed Steel Tools
Authors: Hou Suo Xia , Jia Xiao Ming , Wu C.
Published: March 2009

This paper presents that the high-speed steel tools with solid lubrication material coating can cut without fluid because it has the quality of self-lubrication. With the help of M-2 friction and wearing testing machine and KYKY2800 scan electron microscope, the coating preparation technology and mixture ratio of solid lubrication material in complex coating can be optimized. The results show: phosphate treatment can increase the power of the tools’ surface adsorbing solid lubricant, and the frictional behaviour of solid lubrication coating is excellent when surface roughness of phosphate coating is Ra 2μm~Ra 4μm; molybdenum bisulfide, graphite and trioxid aluminium are mixed together and form a kind of complex coating which has better antifriction effect. The cutting test shows that the solid lubricant coating on the high-speed steel tools can be helpful in increasing the service life of the tools, decreasing the cutting resistance, and reducing the chip deformation and surface roughness of finished work.
The Design and Simulation of Micro Gas Journal Bearing for Micro Gas Turbine Engine
Authors: Dong Ying Huai , Wang Zhen Long , Zhao Yu Cai
Published: March 2009

The dimension of micro turbine engine is usually only few millimeters, so the centrifugal
structure is usually adopt. It must be designed by transonic speed for the higher single pressure ratio.
The speed of the ration axis can reach 105r/min, so the gas bearing is adopt because the general rolling
bearing is impossible. This paper designs a new wedge structure for the micro gas journal bearing.
First the feasibility of this structure is verified by using the FLUENT software simulation. Comparing
the simulation results with various parameters, finally major optimization parameters are confirmed.
Numerical Simulation of Liquid-Solid Two-Phase Flows on Internal and Outside Flow Field in High Pressure Abrasive Water Jet Cutting Nozzle
Authors: Ruan Hong Yan , Liu Hui Xia , Ding S.Y. , Yang K. , Wang Xiao , Cai Lan
Published: March 2009

Based on premixed high pressure water jet cutting, five kinds of nozzle models were
established, and the control equations and closed equtions of liquid-solid two-phase were given. The
inside-outside liquid-solid two-phase flow characteristics of the nozzles were simulated by Hybrid
Finite Analytic Method (HFAM). The results indicate that the taper-beeline nozzle has better
convergence characteristic, good hydraulic characteristic and lower radical velocity, thus it is more
suitable for premixed high pressure water jet cutting nozzle.
3D Reconstruction from Orthographic Image and Optimization Processing of NC Machining for Reconstructed Part
Authors: Liu Jian Ping , Ye Bang Yan , Peng Jian Xi
Published: March 2009

For inverse constructing object from its orthographic image, a new method of 3D reconstruction based on image vectorization and bi-arc approximation of cubic B-spline is investigated. A 3D CAD model is automatically acquired from 2D views by means of 2D primitive recognition, 3D reconstruction of primitive and combination of 3D primitive bodies. With the help of CimatronE8.0 software, reasonable procedure design and optimization toolpath planning are applied to increase machining accuracy and productivity during automatic programming for reconstructed 3D solid. Reconstructed parts are machined on the VMC-600 type machine center with FANUC system. The results of application indicate that this method has many advantages, such as quickly obtaining the CAD model of part, getting smooth machined surface, efficient machining without invalid or reduplicate feed and so on. As a result, it can be applied widely in NC machining field.
Dry WEDM in Improving HS-WEDMed Surface Quality
Authors: Wang Tong , Lu Yu Mei , Hao Shuang Shuang , Xie Shu Qiang , Xu Xiao Cun , Wang Yu
Published: March 2009

This paper studies the surface quality of mould steel with high-speed wire electrical
discharge machining (WEDM) method, which is conducted in gas to improve the accuracy of finish
cut, and compares the surface quality in atmosphere and in emulsion dielectric. Experiment results
showed that WEDM in atmosphere offers advantages such as better surface roughness and higher
material removal rate. The relationship about winding speed and worktable feed on WEDMed
surface quality in semi-finishing cut and finishing cut had been obtained. Morover, a new
attemption was successful in applying dry WEDM in multiple cut to improve surface roughness.
The Fault Tree Analysis of Striking Cylinder of Air Compressor Based on Grey Relation Theory
Authors: Zhou Guang Lin
Published: March 2009

The grey relation analysis method of the grey systems theory is combined with the fault
tree analysis method of reliability theory, and introduced to the analysis and diagnosis of striking
cylinder of piston air-compressor. The various fault pattern occurrence possibilities in fault tree
analysis of the striking cylinder of the piston air-compressor are analyzed and judged by calculating
importance of the bottom event structure of the fault tree as well as the calculating and sorting of
the grey relation degree, which provides theoretical basis for accurately preventing the fault
occurrence. Calculation example showed the effectiveness and reliability of this method.
Study on Fluid Process Measurement Technology
Authors: Pan Xu Dong , Wang Guang Lin , Lu Ze Sheng , Zou S.
Published: March 2009

Process Measurement is a measuring method which is accompanied with process of the
manufacture of work piece. This paper puts forward a new concept of fluid process measurement, and
provides four types of fluid process measurements, which are, pressure pneumatic process
measurement, flow pneumatic process measurement, pressure hydraulic process measurement, and
flow hydraulic process measurement, and establishes the mathematical and physical modal for them.
This paper also provides an example of the application of this measurement method. This
measurement has a good prospect, because it can deal with the work pieces with high-precision,
complex shape and which are hard to be measured in the machining process.
Finite Element Analysis of Thrust Bearing Magnetic Field in 22KW Spindle
Authors: Wu G.Q. , Zhou J.L. , Zhang Xu Dong , Zhang Y.M. , Chi Xiao Ni , Chen X.H.
Published: March 2009

There is a magnetic field inside thrust bearing. The magnetic field distribution is one of
the key factors which decide the running state and performance. With the finite element of ANSYS
software, the magnetic field of thrust bearing has been analyzed. The rule of changes between the
magnetic field and the influencing factors has been discovered. The analysis shows that the
direction of exciting current should be opposite other than identical. The greater the ratio of gap
length between stator and rotor and working gap length is, the less magnetic field leakage is. The
flux leakage of thrust bearing attains 37 percent when the ratio of the gap is 4.0. If the design of a
complete machine is not proper, the flux leakage may attain 20 percent upwards through other gaps
although that of the bearing itself is almost zero. Calculation of bearing capacity indicates that
theoretical value is not exact due to its neglect of magnetic saturation and flux leakage, while FEM
value comparably matches the real substance with considering the magnetic saturation and flux
leakage. The research provides the theoretical basis for optimization of system structure and
selection of current direction control.
The Design and Analysis of Equilibrium Machine for Brake Dish Based on Virtual Kind Machine Technique
Authors: Yan Li , Liu J. , Qiao Wei Jie
Published: March 2009

The balance of brake dish is very important for a car driving. Taking one kind of
auto-equilibrium-machine of brake dish as research object, and making use of the
Virtual–kind-machine technique and the ADAMS software as analysis tools, as well as with the
Solid Works to set up a model, for a whole, the kinematics and dynamics of the product are
analyzed in various virtual environment, the research of dynamics simulation of machine system is
carried out, and various design projects are analyzed Quickly, the experiment is done, which is quite
difficult to be realized by physical kind machine, after all these, an optimal design project of the
system is decided. The virtual kind machine technique is applied through whole design process,
thus the design of the product development becomes convenient, the development period is
shortened, and the product costs are reduced so that optimal-new product can be acquired.
Research and Development on Individual Virtual Intelligent Vehicles
Authors: Lou Yan , He H.W. , Lu Y.M. , Huang C.
Published: March 2009

Aimed at the individual virtual intelligent vehicles, the individual vision behavior and
decision-making behavior of virtual intelligent vehicles are mainly studied. The vision perception
picture and fuzzy neural networks decision-making picture are developed and the virtual intelligent
vehicles on the platform of dynamic intelligent traffic environment have been built by use of the
EONSDK. It not only has improved the reality of traffic environment, and but also can make out the
different traffic environment and can simulate various road accident circumstances.
Measurement and Simulation of Automotive Eddy Current Retarder Based on Virtual Reality
Authors: Wu L.M. , Lai Nan Hui , Wang G.T.
Published: March 2009

Structure and working principles of eddy current retarder (ECR) are discussed, as well as
performance requirements of real-time virtual testing and simulation. On the basis of hardware
testing platform, virtual models of vehicle and retarder are embedded into application program. In
the testing system, Vega API function library is used for second development to control the 3D
models, and Visual C++ is used for mathematical models call from MATLAB to simulate the
working condition. Integrated with virtual instrument and virtual environment, the limitation of
former simulation is broken through. Monitoring and testing on eddy current retarder are achieved
efficiently and visually. Besides, the virtual test data is not only compared with the practical vehicle
test data to correct the technical parameter of eddy current retarder, but also compared with the
simulation of mathematical models for further study. The testing system gives evaluation on the
performance of the retarder in different vehicles, so it expands application range and heightens
testing efficiency.
Discussion on Image Contour Extracting Method of Homogeneous Objects
Authors: Zeng Q.G. , Song S.J. , Qiao C.F. , Zhang J.F.
Published: March 2009

Contour extracting plays an important role in image processing and computer vision, and
it’s one of the most important components in low level processing. Based on many tests, this paper
applies hue and texture as feature combined with mathematical morphology to have a rough
segmentation of homogeneous objects, then restores the obtained contour based on h component.
Tests prove that acceptable contour can be obtained. Compared with traditional method of contour
extracting, the algorithm mentioned here includes self-differing, contour restoring based on hue and
so on, so it has better robustness to light variation.
Study on the Dynamics Control of Industrial Robot Modeling Based on Spatial Operator Algebra Theory
Authors: Fang Xi Feng , Zhang Sheng Wen , Wu H.T. , Lu Y.P.
Published: March 2009

In order to improve the modeling efficiency of the industrial robot dynamics control, the
recursive dynamics is studied based on the Spatial Operator Algebra (SOA) theory, and the procedure
realization is built in the environment of Matahematica6.0 software. The high effective recursive
forward and reward dynamics for the SOA theory, has a simple math expression and a clear physical
meaning. The software structure of the forward and inverse dynamics is built and the industrial robot
dynamics simulation model is realized based on the integrated procedure VB.NET and Mathematica
6.0. According to the analysis, the example of PUMA560 robot forward and inverse dynamics is
studied, and correctness and validity is verified by computed examples.
High Temperature Use Fractal Insulation Materials Utilizing Nano Particles
Authors: Kandell Brian
Published: March 2009

Refractories are used in a variety of processing industries including the ceramic, steel, aluminum,
metal casting and heat treatment industries. Refractories provide thermal insulation, and do so by
providing stagnant or "dead" gas space, namely, they contain a large volume fraction of voids. The
prime criterion for material selection is refractoriness (i.e. use temperature) and the dimensional
stability. One key property required for insulating refractory qualification is the service temperature
limit (STL), which is related to composition, sinterability at use temperature, sintering temperature,
and void volume. During the past ten years nano-pore and nano-scale fractal refractories have
become available which are possibly significantly less toxic when compared to fibrous refractories.
The materials used in fractal refractories are discussed in this article. Apart from use as high
temperature thermal insulators the new class of materials are also finding use in a variety of
products and applications of structural components such as nano-pore high performance coatings,
sensors, filters and membranes used in the electronics, aeronautics, space, energy, and biomedical
engineering fields.
Vapour Phase Preparation and Characterisation of SiCf-SiC and Cf-SiC Ceramic Matrix Composites
Authors: Udayakumar A. , Bhuvana R. , Kalyanasundaram S. , Subrahmanyam J. , Balasubramanian M. , Kannan T.S.
Published: March 2009

Several 2D SiCf-SiC and Cf-SiC composites were fabricated using isothermal and isobaric Chemical Vapour Infiltration (ICVI) process. The reinforcements used in the above composites are Nicalon CG fabric and C fabric. Prior to SiC matrix infiltration, BN and C interfaces were applied to the fibre by using the pre-cursors Boron Trichloride (BCl3)-Ammonia (NH3) and Methane (CH4) respectively to improve the mechanical performance of the composites. SiC matrix was infiltrated by the decomposition of Methyl Trichloro Silane-CH3SiCl3 (MTS) in the presence of hydrogen at the temperature ranging from 950°C to 980°C. H2/MTS flow rate ratio used for this study is 16:1.An appropriate temperature for uniform SiC infiltration without any premature pore closures have been obtained by kinetic experiment. Density and porosity of the above composites were measured using the method described by EN1389:2003. Various mechanical characterizations like flexural strength, tensile strength and fracture toughness of the SiCf-SiC composites were also studied. The SiCf-SiC composites were subjected to thermal exposure (1000°C for 100 hr in an oxidizing atmosphere) and tensile strength results obtained before and after thermal exposure were compared. RT Flexural Strength and Fracture Toughness (KIC) of composite-SQAV (SiCf/C/SiC) and composite-SQBII ( SiCf/BN/SiC ) are measured by 3-point bending and results were compared. RT Flexural strength of Cf-SiC composites with C interface of two thicknesses were measured and
Comparison of the Chemical Reactivity and Bioactivity of Two Bioactive Glasses 47S6 and 48S4
Authors: Oudadesse Hassane , Mami M. , Dorbez-Sridi R. , Pellen-Mussi P. , Perez F. , Jeanne S. , Chauvel-Lebret D. , Cathelineau G.
Published: March 2009

This work is focused on the bioactive glasses obtained by melting and rapid quenching. Two glasses with mineral composition of: 47% SiO2 - 26% CaO - 21% Na2O - 6% P2O5 and 48% SiO2 - 30% CaO - 18% Na2O - 4% P2O5 were investigated. The aim of this study was to establish the kinetics of HCAp layer formation “in vitro” and to control the adhesion and proliferation cells of the two glasses in contact with osseous cells. Obtained results permit to evaluate their chemical reactivity and their bioactivity after immersion in the SBF-K9. Ionic exchanges between biomaterials and SBF liquid during the “in vitro” experiments highlight the differences of the chemical reactivity and bioactivity of 47S6 and 48S4. The structural basis for the effect of cristallinity on the rates of HCA formation in vitro in favour of glasses was also established. The melt derived 47S6 and 48S4 glasses offer to surgeons new compositions with different bioactivity kinetic that bioglassÒ 45S6 and can be adaptable in some other bony pathology.
Single-Component Self-Setting Calcium Phosphate Cement Concept
Authors: Tofighi Aliassghar
Published: March 2009

Single-component, self-setting and injectable calcium phosphate cement (CPC) based on amorphization process of dicalcium phosphate dehydrate (DCPD) is proposed. After preparation of DCPD by wet chemistry, the material was dry milled in an Attritor high energy process (at 400 RPM) during 20 minutes. Experiments were also conducted using a regular ball milling process at 15 and 30h residence time. Amorphization of DCPD confirmed using FTIR, XRD and 31 P solid-states NMR (cross-polarization and decoupling). Upon hydration of amorphized DCPD powder with saline (0.55 ml/g), putty-like consistency produced. The paste hardened in 30 minutes at 37°C and reached a compressive strength of about 20 MPa. The final product was a low crystalline calcium deficient apatite, similar to the composition and structure of bone mineral.
Histomorphometrical Comparison of Alumina-Blasted/Acid-Etched and a Thin Ion Beam Deposited Bioceramic Surfaces at Early Implantation Times. An Experimental Study in Dogs.
Authors: Suzuki Marcelo , Marin Charles , Granato Rodrigo , Coelho Paulo Guilherme
Published: March 2009

Among surface modifications commercially available for dental implants, the incorporation of bioceramic coatings is one of the most popular. However, concerns regarding the effectiveness of the bond between the metallic surface and the coating have led to the development of thin-film Ca- and P- based bioceramic coatings. The purpose of this study was to evaluate the early bone response to a thin ion bean deposited (Test) bioceramic implant surface compared to an alumina-blasted/acid-etched (Control) surface in a canine model. Results showed that although no difference in bone-to-implant (BIC) could be noted between the two different surfaces, more organized bone architecture was present around the Test implants in 4 weeks. Based on this observation, the incorporation of a thin- film bioceramic coating positively influenced bone healing around dental implants at early times.
Effect of Saline Precipitation on the Production of Collagen-Hydroxyapatite (1:1 wt%) Composite
Authors: Campos Doris M. , de Sena Lídia Ágata , de Almeida Soares Gloria Dulce
Published: March 2009

Composites based on hydroxyapatite (HA) and collagen are being used for bone engineering applications. Synthetic composites were produced by precipitating hydroxyapatite in a reaction medium containing collagen fibers. The effect of saline treatment during the procedure of fibrils extraction on the composite morphology, phases presented and in vitro stability was evaluated. The FTIR analysis showed collagen bands well preserved. By Rietveld analysis, additional peaks of sodium chloride were identified on sample made from collagen submitted to saline precipitation. Besides that, the mineral formed phase is a carbonated apatite. This step during fibrils extraction results in larger areas of collagen uncoated and higher stability in culture medium. Despite of this, a cross-linking agent will be necessary to maintain the composite in culture for longer times.
Fibroin-Based Material from Natural Silk Can Be Associated with Alginate and Mesenchymal Progenitor Cells
Authors: Baptista Leandra S. , Pedrosa Carolina S.G. , da Silva Karina R. , do Amaral Ronaldo J.F.C , Kochem Michele C.L. , Menezes Hélio , Sterodimas Aris , de Faria José , de Oliveira Marcio R.R. , Borojevic Radovan
Published: March 2009

Silks are naturally occurring polymers and fibroin, its filament core protein, has been shown to support stem cell differentiation in vitro, and promote tissue repair in vivo. The aim of this study is to develop a biomaterial based on silk-fibroin fibers that can be associated with mesenchymal progenitor cells from human perichondrium in vitro, in order to promote auricular reconstruction in vivo. Silk-fibroin concentrate was dissolved with formic acid solution and freeze-dried in auricular moulds. Fibroin-based material was characterized by scanning electron microscopy and by cytotoxic assays. Perichondrium mesenchymal progenitor cells were characterized by flow cytometry. They expressed the standard mesenchymal stem cell markers, and were able to differentiate into several mesenchymal lineages in vitro. This fibroin-based material is a three-dimensional fibrillar scaffold, non-woven and biocompatible, which was also well integrated with alginate and mesenchymal cells.
Improvement of Bioactivity of Collagen/Alginate Scaffolds by Hydroxyapatite for Tissue Engineering Cartilage
Authors: Sun J. , Wang R. , Zheng L. , Tan Yan Fei , Xiao Yu Mei , Fan Hong Song , Zhang Xing Dong
Published: March 2009

With good biocompatibility, collagen is often used in cartilage tissue engineering. Collagen/alginate composite was hoped to improve the poor mechanical property of pure collagen but the biocompatibity was decreased. In this study, hydroxyapatite (HA) particles were used to get collagen/alginate/HA (CAHA) composite film to enhance the bioactivity properties. The bioactivity of the composite was investigated by in vitro co-culture with chondrocytes. During the 6-day cell culture in vitro, the composite showed a significant improvement in promoting proliferation and maintaining morphology/phenotype of the chondrocytes over collagen/alginate composite by MTT, SEM, fluorescent and immunohistochemical assays. Cytocompatibility and cytoviablility of CAHA even come up to that of collagen film alone. The results indicated that the composite film may provide an appropriate environment for the proliferation and maintaining the morphology and phenotype of chondrocytes and have a potential clinical application in the cartilage tissue engineering field.
Water Absorption and Mechanical Properties of Cements Based on Poly (Methyl Methacrylate) (PMMA) as Function of Hydroxyapatite (HA) Content
Authors: Ionita D. , Tihan G. , Marques A.T.
Published: March 2009

The purpose of this study is the obtaining of different orthopedic materials and chemical and mechanical characterization. The chemical tests used were setting time, water absorption and from the point of view of mechanical properties the Young modulus, compressive strength, and maximum strength. Also, the surface of orthopedic bioceramics materials was characterized by porosity test.
Application of New Statistical Approach to Study Drug Release from OCP Coating on Titanium Sheets
Authors: Fuentes Gastón , Peón Eduardo , Campos Yaíma , López Noeldrys , Resende Christiane Xavier , de Almeida Soares Gloria Dulce
Published: March 2009

In this study, commercially pure titanium (Ti-cp) discs were used as substrates. Octacalcium phosphate (OCP) layers were deposited by immersion of Ti-cp discs up to 7 days into Solution for Bioactivity Evaluation (SBE) and characterized by SEM-EDS and XRD. The OCP coatings were doped with cephazolin or cefalexin by individual immersion in 300 ppm of each solution for 24 h at room temperature. The non-existence of mathematical models to explain drug release from these matrixes made the choosing of correct model, a complex process. Five non-linear mathematical methods were employed in order to identify the possible drug release mechanism using Akaike and Bayesian Information Criterion (AIC and BIC respectively) and its derivatives. The best model was Peppas & Sahlin that consider two stages in release: pure diffusion in first stage, and drug dissolution and migration through the porous matrix at second stage.
Targeted Local Delivery of Bisphosphonate from Orthopaedic Implants
Authors: Åberg Jonas , Brohede Ulrika , Mihranyan Albert , Strømme Maria , Engqvist Hakan
Published: March 2009

Two methods of loading bisphosphonate (BP) into hydroxylapatite (HA) coatings on crystalline TiO2 surfaces were investigated to improve bone ingrowth to implant surfaces. In the study the BP pamidronate was used. Ti-plates coated with crystalline TiO2 were soaked in phosphate buffer saline (PBS) for 7 days at 40° C and thereafter soaked in solutions of BP, 0.5 mg/ml for 15 or 60 minutes (fast loading method). In the second method BP was dissolved into PBS in different concentrations before immersion of the discs for 7 days (co-precipitation method). Surface and bulk were analysed using electron spectroscopy for chemical analysis, scanning electron microscope and x-ray diffraction. Release of BP was studied using alternating ionic current method. It was shown that fast loading by soaking in a BP solution for 15 minutes was sufficient to load BP into a HA coating. Co-precipitation showed that a thin layer of calcium phosphate crystals containing BP can be deposited directly onto a crystalline TiO2 surface.
Therapeutic Effects of Paclitaxel-Loaded Hydroxyapatite-Alginate Beads: In Vitro  and In Vivo Studies
Authors: Abe Tetsuya , Sakane Masataka , Ikoma Toshiyuki , Kobayashi Mihoko , Ochiai Naoyuki
Published: March 2009

Several drug delivery carriers have reported on local delivery of paclitaxel (PTX), but their effects on intraosseous cancer model are not well known. This study was conducted to clarify the therapeutic effects of our newly developed PTX-loaded HAp-alginate composite beads. Cytotoxic activity was assessed on rat’s mammary adenocarcinoma by cell proliferation assay using WST-1 reagent. Antitumor activity was assessed by 8-week-old rat female Fischer 344 rats of metastatic spine cancer. Twenty-three rats were divided into 3 groups: Group 1 (n = 7) and Group 2 (n = 8) was treated with the PTX-loaded HAp-alginate beads using strontium ions and barium ions, respectively. Group 3 (n = 8) was administered with drug-free HAp-alginate beads. We checked disease-free time and survival time among 3 groups. The HAp-alginate beads containing 2.4wt% of PTX showed significant cytotoxic activity on CRL-1666 cells. The effects were decreased with time during 72 h. The animals treated with 2.4wt% of PTX-loaded HAp-alginate beads showed 40% increase in the disease-free time and 25% increase in survival time. Our studies suggest that newly developed HAp-alginate beads can be a candidate carrier of PTX to bone.
Influence of Processing on Mechanical Properties of Hydroxyapatite
Authors: de Oliveira Marize Varella , Schaerer Magna Monteiro , Pereira Robson Pacheco , Caminha Ieda Maria V. , Santos Silvia R. A. , Rossi Antonella M.
Published: March 2009

In the present work, mechanical properties of a stoichiometric hydroxyapatite (HA), synthesized by hydrothermal method, with 1.66 Ca/P molar ratio are investigated as a function of the processing parameters. Cylindrical samples were processed by uniaxial compacting, followed by sintering, aiming to obtain high density HA samples. Density values were obtained by the geometric method and SEM images were taken from HA samples in order to characterize their topography and to determine the grain size for each set of samples. Vickers micro-hardness was measured for each set of samples. Compressive strength of cylindrical samples with 2.0 mean diameter/height ratio was measured reporting load to failure divided by the cross-sectional area of the samples. Vickers micro-hardness and compaction strength values of the samples were found to be in agreement with the relative density and grain size values.
Effect of Saturation and Post Processing on 3D Printed Calcium Phosphate Scaffolds
Authors: Szucs Tamas D. , Brabazon Dermot
Published: March 2009

Three dimensional printing was investigated for fabricating hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) composite scaffolds using calcium phosphate based ceramics and calcium phosphate cement chemistry. Scaffolds were formed by printing an aqueous sodium phosphate solution on the powder bed consisting of a mixture of dicalcium phosphate anhydrous (DCPA) and calcium hydroxide powders. The sodium phosphate solution was functioning as a binder material and also as the initiator of the wet chemical reaction. Compressive mechanical properties of printed samples were examined as a function of saturation level that was inversely proportional to the powder to liquid ratio. To increase mechanical properties and obtain hydroxyapatite and β-TCP composites, the printed samples were sintered. The effect of sintering parameters including dwell time and sintering temperature were also examined. X-ray diffraction (XRD) was used to examine material composition at different stages of the manufacturing process and to confirm the presence of HA and β-TCP in the final stage. The effect of sintering procedure on the surface topology of the samples was examined using scanning electron microscopy (SEM).
Use of Ceramic Scaffolds as Inductors of Extramedullar Hematopoiesis
Authors: Schechtman H. , Pelajo-Machado M. , Prado da Silva Marcelo Henrique , Müller C.A. , de Andrade R.G. , Lenzi Henrique L.
Published: March 2009

The extracellular matrix in skeletal tissue besides being responsible for its structure and function also provides key regulatory signals for cell proliferation and differentiation by interacting directly with cell receptors, controlling the diffusion of soluble growth factors. Immature bone marrow cells can migrate through capillaries to systemic circulation as well as return to bone marrow. This phenomenon is the biological basis for bone marrow transplant. The mechanisms that control the migration and the return of these immature bone marrow cells are still to be described in a generally accepted model. Thirty days-old Wistar rats were employed as recipients for the implantation of ceramic blocks or demineralized femur diaphysis. The material was implanted subcutaneously at the dorsum. The rats were euthanized with CO2 at 15, 40 and 68 days after implantation. The whole area of implantation was harvested from skin deep up to the muscle. Liver, spleen, lungs, femurs and the vertebral spine, ribs and sternum were also harvested. The harvested material was fixed in Millonig formalin and decalcified with EDTA, if applicable. The material was then progressively dehydrated in alcohol, immersed in xylol, impregnated and embedded in paraffin. The paraffin blocks were then sliced in 5µm sections with a microtome, stained in Haematoxilin – Eosin, Lennert's Giemsa and Gomori's reticulin for histological analysis under brightfield optical microscopy. All implants produced an intense fibroblastic reaction, angiogenesis and subsequent modulation into a loose stroma. However, hematopoesis was not observed. Implantation of endogenous haematopoetic cells in an inductive stroma, which might propitiate hematopoesis is a model scarcely studied. Experiments such as the one described here might be good models for understanding the sequence of events leading to formation of the stroma and implantation and differentiation of haematopoetic precursors.
Freezing and Thawing Resistance of Cement Asphalt Mortar
Authors: Hu Shu Guang , Wang Tao , Wang Fa Zhou , Liu Zhi Chao , Gao Tao , Zou Jin Zhong
Published: March 2009

In this paper, freezing and thawing resistance of CA mortar was investigated and some influential factors such as the ratio between asphalt emulsion and cement (A/C), cement types, various additives were also explored. Results indicated that a gain of mass was observed for every mixture after the test; mixtures with a higher A/C performed better in terms of higher relative elastic moduli. Mixtures proportioned by partially replacing ordinary Portland cement (OPC) with sulfoalumninate cement (SAC) underperformed in freezing and thawing property. Addition of crumb rubber powder (CRP), redispersible polymer powder (RPP) and organic fiber (FR) improved the resistance of CA mortar to freezing and thawing while that of silica fume (SF) undermined it.
Study on Damping of Reinforced Concrete Materials and Members
Authors: Leng Qiao Juan , Qian Jiang , He Yi Bin
Published: March 2009

According to the spatial distribution theory of damping energy dissipation, the calculation formula of damping energy dissipation and damping ratio of a cantilever beam in one cycle are derived. It is shown that the damping characteristic of a member is affected by the material damping characteristic, stiffness distribution, mode of vibration and the sectional shape of the member, etc. The damping energy dissipation coefficient J for reinforced concrete materials is calculated by using the proposed formula considering different concrete strength, elastic modulus and reinforcement ratios based on test data available.
Experimental Research and Analysis on the Flexible Behaviors of High-Strength Concrete Thin-Walled Box Girder
Authors: Zhu Ming Qiao , Fang Zhi , Yu Zhi Wu , Wei Qi Zhi
Published: March 2009

A full test on the flexible behaviors of the long flanges and trapezoidal section high-strength concrete thin-walled box girder has been performed. The deflection horizontal distribution, strain and strain distribution of concrete and reinforced bars in the compressive flanges, strain distribution along rib height have been studied. The results demonstrate that reinforced concrete thin-walled box girder has fine flexible behavior and ductility, strain distribution along rib height agrees with the basic assume, i.e. Plane section before deforming remain plane, and the destructive experimental results disclosed the full process law of shear lag effect and equivalent calculated coefficient of compressed flange width at middle span section, which can be served as a reference for that applying elementary reinforced concrete beam theory settles the ultimate flexural capacity calculation of concrete thin-walled box girder.
Development of Lightweight Aggregate Concrete Containing Pulverized Fly Ash and Bottom Ash
Authors: Litsomboon Theradej , Nimityongskul Pichai , Anwar Naveed
Published: March 2009

This study examines the feasibility of using different lightweight aggregates (LA) and bottom ash as coarse and fine aggregates in concrete with fly ash. The lightweight materials were composed of 3 types, namely pumice, cellular lightweight aggregate and MTEC lightweight aggregate. The tests for physical and mechanical properties of lightweight aggregate concretes (LWAC) were conducted in terms of workability, compressive strength, apparent density, abrasion resistance and absorption. Test results showed that compressive strength of LWAC increased with an increase in apparent density, which is mainly depending on the type of aggregate. The replacement of normal weight sand with bottom ash resulted in a decrease both in density of concrete by 180-225 kg/m3 and 28-day compressive strength of concrete by 16-26%. Moreover, the use of bottom ash to replace sand in concrete increased the demand for mixing water due to its porosity and shape and to further obtain the required workability. The type and absorption of LA influenced predominantly the water absorption of LWAC. Total replacement of natural sand by bottom ash increased the absorption of the concrete by 63-90%. With regard to abrasion resistance, the abrasion resistance of lightweight aggregate concrete was mainly dependent on the compressive strength of concrete: the higher the strength, the higher the abrasion resistance of LWAC. In addition, the use of bottom ash as a fine aggregate resulted in a lower abrasion resistance of lightweight aggregate concrete due to its porosity. Of the three types of lightweight materials, MTEC LA had achieved both low density and high compressive strength.
Effect of Curing Conditions on Property of High Performance Concrete with Composite Mineral Admixture
Authors: Gong Ling Li , Jin Nan Guo , Gu Xiang Lin , Jin Xian Yu
Published: March 2009

In this paper, the development of cubic compressive strength of concrete with the age was studied first. Four kinds of concrete, which were made from the mixes by using 0%, 20%, 30% and 40% Composite Mineral Admixture (CMA) as the replacement of the cement for each kind of concrete, were used in the study. Test results showed that the concrete with 30% CMA had the best properties compared with others both under standard-curing condition and steam-curing condition. Furthermore, the normal concrete (without CMA ) and the high performance concrete (with 30% CMA) were chosen as the main materials in comparative tests to study the effect of curing conditions on the property of high performance concrete, such as the basic mechanical properties, the property against chloride penetration, and the property against carbonization. The results indicated that the curing temperature would increase the concrete strength in early age but not in long term. The curing condition would affect the property of concrete against carbonization but not the property of concrete against chloride penetration obviously.
Experimental Research on Concrete Filled Thin-Walled Steel Tube Long Columns
Authors: Cao Bao Zhu , Zhang Yao Chun , Zhao Yue Ming
Published: March 2009

Experimental research on square and octagonal concrete filled thin-walled steel tube long columns of 6 specimens in axial compression and 8 specimens in eccentric compression is undertaken. The relationship of global buckling bearing capacity of the columns and local buckling of the steel tubes is obtained. The test indicates that local buckling occurs in steel tube of each column before it reaches ultimate capacity, and has little effect on global buckling performance. The ultimate load decreases obviously with the increase of slender ratio and eccentricity. The ductility of columns increases with the increase of steel ratio in composite sections. Composite beam element of ANSYS is adopted in the finite element analysis. The theoretical results are agreed well with test..
Development and Advance in Adding-Storey Retrofit of Existing Buildings in China
Authors: Gao Jian Ping , Chen Wei
Published: March 2009

Residential houses and civil buildings in China were mainly low-rise buildings before 1980s. With the rapid development of urban construction, urban land became more and more scarce. Thus in recent years, it becomes increasingly popular nationwide to add more stories to existing building for its particular techno-economy advantages. Adding-storey plays an important role in mitigating the pressure of demand for more building sites, improving the living condition，and accelerating the modernization progress of cities’ shabby zones. In this paper, a brief review was presented on the evolution, status-quo and trends of the adding-storey of existing buildings in China, and three new adding-storey methods using passive control technology were introduced, which can be used for peers' reference.
The Program Design of the Variable Cross-Section of Concrete Continuous Skew Beam Bridge
Authors: Chen Min , Tian Zhong Chu , Zeng Guo Liang
Published: March 2009

In practical engineering, we often encounter designs of variable cross-section or compound section skew girder bridge. While in many bibliographies, uniform cross-section of the concrete beams studying was carried out, but few of variable cross-section concrete beams were in-depth studied. Based on analyzing the mechanical behavior of variable cross-section beam skew girder bridge, the semi-analytic solution of variable cross-section beam skew girder bridges were provided in this paper. With this method developed a planar computation program to resolve the calculation problems of skew girder bridge, a more convenient way will be brought up for designers in calculation.
Nonlinear Analysis of Interaction of Superstructure-Pile-Raft-Soil System in Layered Soil — Part I: Formulation of Interaction Equation
Authors: Chen Jun , Chang Yong Hong , Zou Yin Sheng
Published: March 2009

The layered soil model is used to simulate the nonlinear performances of the layered soil in this paper. Using the shear-displacement method, the flexibility coefficients of the pile-pile and the pile-soil are deduced based on the interaction mechanism of the pile-pile and the pile-soil in the layered soil. After that, the stiffness matrix of the pile-soil system can be established. Using coupling method presented in this paper, the interaction equation of superstructure-pile-raft-soil system is formulated. The interaction equations are used to analyze the reaction force on the pile head and the displacement characteristics of the raft of the piled-raft foundation in the layered soil and its practicality is excellent.
Seismic Performance of Reinforced Concrete Beam to Concrete-Filled Steel Tubular Columns Joints
Authors: Qu Hui , Han Lin Hai , Tao Zhong
Published: March 2009

In this paper, eight reinforced concrete (RC) beam to concrete-filled steel tubular (CFST) column joints enclosed by rebars were tested under reversal horizontal displacement with constant axial load in order to study their seismic behavior. The test parameters are axial load level and the section type of CFST column. In this study, the failure model, hysteretic characteristic, ductility and energy dissipation were investigated. The results indicated that the anti-earthquake abilities of all joints satisfied with the demand on the code.
Modeling the Behavior of Insulated FRP-Strengthened Reinforced Concrete Beams Exposed to Fire
Authors: Gao Wan Yang , Lu Zhou Dao , Hu Ke Xu
Published: March 2009

External bonding of fiber reinforced polymer (FRP) composites has become a popular technique for strengthening reinforced concrete (RC) structures all over the world. So far, very little information is available on the fire performance of FRP-strengthened concrete members. The analysis presented here aims to develop a nonlinear finite element (FE) model of FRP-strengthened RC beams exposed to fire. The analysis consists of two portions: the initial portion is the calculation of the transient temperature distribution and the second portion is the structural response analysis due to the effect of thermal and mechanical load. The proposed numerical analysis is validated against proving fire tests. The results indicate that the predicted temperatures and deformations are shown to agree to the tests satisfactorily.
Low-Cycle Fatigue Test of Circular Concrete Filled Tubular Columns
Authors: Zhang Guo Wei , Xiao Yan , Kunnath Sashi K.
Published: March 2009

During earthquake, the inelastic action in the plastic hinge regions of structures and bridges results in significant reversed deformation and failure of the critical components because of cumulative damage. To simulate seismic behavior of structure members and develop a simplicity damage criterion for circular concrete filled steel tubular (CFT) columns subjected to a series of earthquake excitations, an experimental study was undertaken to investigate the cumulative damage and relationship between low cycle fatigue life and displacement amplitude. Two types of large scale circular CFT columns with different kinds of seam weld and inner concrete compressive strength including nine specimens were tested under quasi static loading with constant and variable cyclic amplitudes. The test data were evaluated with the fatigue model relating deformation and fatigue life. Fatigue life expressions for application in damage-based seismic design are developed.