bluuebunny/crossref_metadata_2025 huggingface dataset:
Real Time Defects of Beer Bottle Detection System Based on DSP
Authors: Ren B. , Xie Tan Cheng , Nan X.
Published: March 2009

The paper analyses the problem of beer bottles detection techniques on the beer bottles
production line, uses digital image processing technique on the beer bottles online defect detection.
The paper puts forward the designing ideas of the hardware, developing flow of the software and
the algorithm of beer bottles detection. TMSDM642 is used to set up the real-time video processing
system of the hardware .The hardware system is mainly composed of three parts: the part of
memory, the part of the input and the part of the output. When beer bottles are put into the work
area, the video images of the bottle-mouth and bottle-bottom will be gained by the CCD camera,
firstly, preprocessing is used to eliminate video image noise. Secondly, the image segmentation
algorithm is used to detect defects in video images. Lastly the goal of extracting defects will be
accomplished. The experimental result indicated that this system may effectively exam the flaw or
the unqualified beer bottles.
Effect of Focusing Status on Dimension Measurement Accuracy in Micro Measurement System Based on CCD
Authors: Guo Hua , Bai L. , Liu J. , Shi Y.
Published: March 2009

This paper adopted the photoelectric micro measurement system based on CCD which was
independently developed by Laboratory of Process Automatic and Detection Harbin Institute of
Technology to detect dimension of the small precise parts. Under the various focusing status, it was
discovered that articulation of focusing has huge effect on the measurement of measurand. According
to the characteristics of measurand, we adopted the entropy function as the evaluation function of
automatic focusing, developed a special software to process entropy value of the picked images, and
obtained the relationship of focusing evaluation function and measurement error through a large
number of experiments. The experimental result effectively verified the effect of articulation of
focusing on dimension measurement.
Visual Simulation Study of Pick Loads on Continuous Miner
Authors: Li Xiao Huo , Ma X.H.
Published: March 2009

A continuous miner is one of wall mechanized coal face; its design quality and
performance have directly effect on coal productivity and economic benefits. A pick on a
continuous miner, contacting with coal and rock, is a tool cutting directly coal and rock, its force
condition during it cuts determines directly loads of the cutting mechanism, pick wear and tear,
fabric vibration and cutting performance of the machine, is the basis for the design of a continuous
miner. By considering a variety of factors, a mathematical model, including the coal and rock
properties, structural parameters of a pick, pick sequence, cutting parameters of the continuous
miner, is established in the paper, visualization software which can be directly reflected pick' forces
on the continuous miner is design. On this basis, pick' forces of a continuous miner under different
working conditions are simulated and studied, which create conditions for understanding pick' force
during cutting process of a continuous miner, computer-aided design of the cutting mechanism,
dynamic design and research of the machine.
AX-MV6 Robot Bevel Cuts the Workstation System the Applied
Authors: Kong Xiang Bing , Cui Yue , Yao Yao
Published: March 2009

According to the spatial hot cutting characteristic and the user technological requirement,
designed robot bevel have cut the workstation control system based on OTC the AX-MV6.This
article introduced the system hardware constitution and the principle of work, the air course control
system, the robot and the controller function, the spatial hot cutting control programming method
and so on. This system definitely may under the robot control, complete to steel plate each kind
two-dimensional (for example plane) and three dimensional (for example bevel) cuts the work, uses
in metal plate random graph cutting and bevel cutting. Confirms this system performance after the
production to be stable, the work piece cutting quality is good, the production efficiency is high.
Development of a CNC System for Multi-Axis EDM and its Realization
Authors: Huang Hai Peng , Wang Zhen Long , Zheng J.M.
Published: March 2009

This paper presents a new kind of multi-axis electro-discharge machining (EDM) computer numerical control (CNC) system which is based on RT-Linux platform. Binary kernel structure of EDM CNC System is proposed to handle real-time task and time-sharing task separately. The system is divided into three parts: CNC kernel module, CNC driver module and CNC user module. CNC kernel module implements CNC control function in of the software system, and implements the move control to the NC machine. CNC driver module is just as device driver level. CNC user module is user manage procedure. The experiment of rimed turbine blisk validates the performance of the system. The performance implied that the system is real-time, stable and reliable.
Design and Establishment of Platform of Tripedal Industrial Robots
Authors: Pa Pai Shan
Published: March 2009

Modern industries use many types of robots. The biped or quadped robots are the most common robots in the robot category. However, in terms of efficiency, flexibility, and stability, the developing tripedal robots could be the best candidate. The research starts from establishing the platform of the tripedal robots. The mathematic model of the tripedal robot is generated by applying the forward kinematics and the inverse kinematics. The research then adopts the MSC Virtual Nastran simulation software to calculate the optimal values applied to the tripedal robots for verification. The major issue is about the balance of the static stability and dynamic stability. The research also tries to develop the most power-saving method and the largest moving steps. The platform of the tripedal robot will become a significant design reference for the commercialization of different industrial robots, and it will provide the design of industrial robots with more options and useful applications.
Application of Chaos PSO Algorithm in the Decelerator Optimization
Authors: Liu Yi Xiang , Jin Xiang Yang
Published: March 2009

The problems of slow convergence speed and being prone to converge to minimum were solved by combining the characteristics of chaos dynamics in the paper, whose characteristic of combining chaos optimal ergodicity and particle swarm optimal rapidness conquered deficiency of the traditional PSO algorithm. The proposed algorithm used for the decelerator of the electric submersible progressive cavity pump (ESPCP) design optimization compared with that of which was based on the standard PSO and genetic algorithm. By use of property mentioned, optimization searching could be carried out, firstly a series of chaos variables were produced as same number as optimization variable, then chaos was lead into optimization variable by the way of similar to carrier, that made the optimization variable into a chaos state, at the same time, the extent of chaos emotion was magnified to the value range of optimization variable, at last searched by chaos variable, searching technique based on chaos had more superiority than other searching technique. The results showed that the proposed algorithm was superior to the other two algorithms with a better astringency and stability. This article offered a new optimization method in machine.
Study on Minipore Drilling to Stainless Steel 1Cr18Ni9Ti
Authors: Tang Yong , Ye Bang Yan , Wu Qiang , Wang W.W. , Lai Xing Yu
Published: March 2009

Based on reviewing the applications and machining of the stainless steels, the cutting
performance of the austenitic stainless steel 1Cr18Ni9Ti is analyzed through the contrastive
experiments. This paper studies drilling minipore mechanics of hard-to-cut material—Austenitic
Stainless Steel 1Cr18Ni9Ti by simulation and experiment, analogy results displays the trend that
drill thrust, torque and temperature changed with amount of feed, it matches with test result in the
same cutting condition well. The research results would be of great benefit for the selection of
proper tools and cutting parameters in drilling austenitic stainless steels.
Influence of the Air-Gap Changes on the Performance of Linear Induction Motor
Authors: Zhu Xi Lin , E Shi Ju , Gao Chun Fu
Published: March 2009

The transient characteristic of single-sided linear induction motor (LIM) was simulated and computed using the electromagnetic field finite element analysis software Ansoft. The change of the thrust, the primary current and the air-gap’s magnetic field of linear induction motor was analyzed under the different air-gap’s size condition. The analysis result shows that, with the growth of air gap, the motor thrust reduces but the primary current increases, and the distribution of motor air-gap magnetic field is uneven due to the existence of end effects. Finally a comparison is made between the simulation result and the experiment result, which indicates the correctness of simulated model, thus it can provide important basis for the manufacture, optimized design and control of LIM which is used in subways.
Modeling and Simulation of Milling Force in Virtual Numerical Control Milling Process
Authors: Sui Xiu Lin , Zhang Jia Tai , Ge Jiang Hua , Wang Ya Ping , Yuan H.
Published: March 2009

A parameter equation based on cutting edge of ball-end mill is set up by analyzing the parameters of ball-end mill influence the milling force in virtual NC milling process. The relationship among elemental cutting force, instantaneous radial chip thickness and cutting edge length is analyzed, and the dynamic milling force of ball-end mill at arbitrary feed direction is established. The milling force parameter model by quadratic regression equation in different cutting conditions is built. Through experiments in NC machining center and using orthogonal combination and principal components analysis, the regression coefficients are calculated. The correctness of milling force model is testified by experiments. All these can provide theoretical basis for physics modeling and simulation of virtual numerical control milling.
NC Lathe Redesign and Green Estimation
Authors: Ding J.M.
Published: March 2009

According to the requirement of NC lathe in green redesign, today’s NC lathe redesign and
analyze are put up. CKA6150 NC lathe is redesigned. The green indices are established. A method is
used to estimation and analyze in CKA6150 redesign scheme. The result indicates that the new
scheme is prior to the old one, and meets absolutely the requirements of the green redesign.
Research on Integrated System of Information and Function Based on Virtual Prototyping Technology
Authors: Yan Bingbing , Ren Fu Jun , Jiang Y.C.
Published: March 2009

Virtual prototyping technology as a key technology for agile manufacturing can deal with multidisciplinary knowledge across different fields. In the complex product development process, the exchange between heterogeneous data in heterogeneous environment is a universal problem encountered, which increases the complexity of collaborative parallel design of virtual prototype. Taking the product models as carriers and the different function requirements as clues, the knowledge structure and expression of product information in various fields was studied. By adopting component object model technology, direct geometry access technology, behavioural modeling technology and parametric design thinking, the interaction among tools in various function units was realized, and the effective integration of information and function in multi-fields was accomplished, the parameter-driven virtual prototype architecture of complex product based on the integration of information and function was created. The feasibility of this architecture has been verified by the actual engineering. This plan provides an effective way to carry out virtual prototype projects for enterprise.
Bone-Like Apatite-Forming Ability of Ca3(PO4)2-CaMg(SiO3)2 Ceramics in Simulated Body Fluid
Authors: García Carrodeguas R. , Córdoba E. , De Aza A.H. , De Aza S. , Pena P.
Published: March 2009

In this study a ceramic composite with nominal composition 40 wt% Ca3(PO4)2 – 60 wt% CaMg(SiO3)2 was obtained by solid state sintering of compacts of both synthetic fine powders. The ceramic composite showed a fine grained and homogeneous microstructure consisting of CaMg(SiO3)2 and b-Ca3(PO4)2 grains. The results of X-ray diffraction and scanning electron microscopy demonstrated that, during soaking in SBF, the grains of β-Ca3(PO4)2 dissolved preferably than those of CaMg(SiO3)2, leaving a porous surface layer rich in CaMg(SiO3)2. Subsequently, partial dissolution of the remaining CaMg(SiO3)2 occurred and the porous surface of the b-Ca3(PO4)2-CaMg(SiO3)2 ceramic became coated by a bone-like apatite layer after 7 days in SBF.
Hydrothermal Degradation of Zirconia Bioceramics: Effect of Ternary Oxide Additions
Authors: Nogiwa-Valdez Akemi A. , Rainforth Mark W.
Published: March 2009

Phase transformation of 3Y-TZP with different ternary oxide additions (Al2O3, La2O3, Sc2O3 and CeO2) was evaluated by hydrothermal degradation tests in water vapor at 180°C. Monoclinic phase quantification from XRD patterns showed an improved degradation resistance of the specimens with oxide additions in comparison to the 3Y-TZP base material. Cross sectional sample analysis showed that, even though for all the compositions the exposed surface became saturated with monoclinic phase, the penetration of the transformation varied. Alumina-lanthana doped materials exhibited the thinnest degraded layer.
Synthesis of Si-Substituted β-Tricalcium Phosphate Ceramics with Controlled Composition
Authors: Mekki-Berrada M.Kamal , Damia Chantal , Champion Eric
Published: March 2009

Pure b-tricalcium phosphate (bTCP) and Si-substituted b-tricalcium phosphate powders with compositions ranging from x = 0.01 to 0.20 were synthesized using a wet precipitation method. The results showed that the addition of Si decreased the maturation time of single-phase Si-substituted bTCP. For longer maturation time, other phases were observed such as hydroxyapatite (HA) and a-tricalcium phosphate (aTCP). The Si incorporation was confirmed by X-ray diffraction with Rietveld refinement, indicating an increase of the lattice volume from 3524.88 Å3 for pure bTCP to 3527.41 Å3 with increasing Si content.
ICP/MS in Evaluation Heavy Metal Influence on the Behavior of Natural Temporary Teeth
Authors: Demetrescu Ioana , Luca R. , Ionita D. , Bojin D.
Published: March 2009

The aim of this paper is to evaluate using ICP/MS (inductively coupled plasma mass spectrometry method ) the small amount of heavy metal existing in temporary teeth of children from area with high environmental risk regarding heavy metals, and to correlate this amount with the state of degradation of such teeth, taking into account that teeth are biological archive.
A Comparative Study between α-TCP and Si-α-TCP Calcium Phosphate Cement
Authors: Motisuke M. , García Carrodeguas R. , Zavaglia Cecília A.C.
Published: March 2009

On this study the influence of silicon dopping on the properties of the final calcium phosphate cement were analysed and compared to the ones of the conventional Si and Mg-free α-TCP cement. In spite of silicon doping, Si-α-TCP calcination temperature (1400°C) was higher than the one used for conventional α-TCP (1300°C) as a result of Mg contamination on the commercial precursor used on the Si-α-TCP synthesis. Because of the high temperature used, Si-α-TCP sample was difficult to mill. Even after 1 week milling, the particle size achieved was 12µm while Si-free α-TCP reached 7.7µm. Consequently, the reactivity of both powders was different. In conclusion, the properties of Si-α-TCP cement were not satisfactory for clinical application. In order to do it so, it is essential to enhance the powder reactivity by reducing Mg contamination, lowering the sintering temperature and reducing the particle size to, then, achieve the desired reactivity and compressive strength.
A NMR Investigation of Borate Incorporation in Apatitic Biomaterials
Authors: Barheine Sabrina , Hayakawa Satoshi , Osaka Akiyoshi , Jaeger Christian
Published: March 2009

The incorporation of ions in the lattice of hydroxyapatite alters significantly its structure. Particularly, if anions such as trigonal borate units are accommodated in the lattice severe distortions must occur around the substitution site because of different geometric shape, electric charge and anion size. Solid-state NMR has been used to investigate this problem in detail for a hydroxyapatite sample synthesized by high temperature solid state reaction. The results clearly verify the existence of network distortions. Indeed, only about 1/3 of the total phosphate content forms crystalline hydroxyapatite (also found in XRD) whereas the residual amount is contained in two different phosphate sites with 31P chemical shifts of 5.5 ppm and 2.3 ppm, but broad resonances lines suggesting disorder. Furthermore, a novel proton signal at -0.6 ppm was found which is directly associated with the borate incorporation. No specific correlation of the two structurally different borate units with the two phosphate groups is found.
Polymeric Calcium Phosphate Cements Incorporated with Poly-γ-Glutamic Acid
Authors: Kim Sung Soo , Lee Sung Jae , Kim Yong Sik , Lee Kwon Yong
Published: March 2009

Polymeric calcium phosphate cements (PCPC) derived from biodegradable poly-g-glutamic acid (g-PGA) were prepared in an attempt to improve the mechanical strength of calcium phosphate cement (CPC). The characteristics of the PCPCs were compared to those of cement incorporated with citric acid. The diametral tensile and compressive strengths of the CPC incorporated with g-PGA were significantly higher than that of cement incorporated with citric acid at equivalent concentrations (p<0.05). The maximal diametral tensile and compressive strengths of the CPC incubated for 1 week in physiological saline solution were approximately 18.0 and 50.0 MPa, respectively. However, the initial setting time of the PCPC was much slower than that of CPC incorporated with citric acid. The formation of ionic complexes between calcium ions and g-PGA was observed using FT-IR spectroscopy. Hydroxyapatite (HA) formation was retarded by g-PGA incorporation according to scanning electronic microscopy (SEM) and powder X-ray diffraction (XRD) observations.
Influence of Electrolyte Composition and Time Deposition on TiO2 Films Produced by Micro-Arc Oxidation
Authors: dos Santos Amanda , Lidizio Leandro Reis , Santos da Cruz Talita , de Sena Lídia Ágata , Damasceno Jailton Carreteiro , Achete Carlos Alberto
Published: March 2009

In this study, the influence of electrolytic composition and time deposition parameters on the quality of titanium oxide coating was evaluated. The commercial Ti discs were anodized by micro-arc oxidation (MAO) process using calcium acetate monohydrate 0.5M (CaAc) and a mixture of calcium acetate monohydrate 0.5M and sodium beta-glycerophosphate 0.02M (CaAc + BGF) aqueous solutions. MAO was carried out by applying pulsed DC voltage of 150 V at different processing time (05, 15, 30, 45 and 60 seconds). The films were characterized by SEM, EDS, surface profilometer and XRD. Additionally, osteoblasts culture was carried out in order to verify the cytocompatibility of the anodized surfaces. The results showed the formation a well controlled homogenous microporous structures with irregular shapes for both electrolytes. Presence of Ca and P on the surface was found for films produced with CaAc + BGF electrolyte. Also, the adhesion, spreading, proliferation, and differentiation of osteoblast cells were very similar.
The Manipulation of Properties of Ti Bioalloys at Micro and Nanoscale Using Etching Procedures
Authors: Ionita D. , Raducanu Doina , Prodana Mariana , Demetrescu Ioana
Published: March 2009

The paper is an electrochemical study regarding the influence of different acid etching conditions on the corrosion behaviour of a new Ti based bioalloy with Nb, Ta and Zr. Open circuit, potentiodynamic and electrochemical impedance spectroscopy were the methods performed in a simulated body fluid (SBF) and a stability mechanism was discussed in terms of equivalent circuits.
Fast Loading, Slow Release – A New Strategy for Incorporating Antibiotics to Hydroxyapatite
Authors: Forsgren Johan , Brohede Ulrika , Mihranyan Albert , Engqvist Hakan , Strømme Maria
Published: March 2009

The aim of this study was to investigate if it is possible to fast load hydroxyapatite with antibiotics and still obtain a slow but therapeutic release of drugs during several hours. Physical vapour deposition was used to coat commercially pure titanium with a layer of anatase TiO2. On top of this, a layer of hydroxyapatite was deposited using biomimetic precipitation. This hydroxyapatite coating was then soaked in solutions containing antibiotics for various amounts of times. The release rate of the antibiotics was measured in PBS during 22 hours. The released amount was compared with the results from an antimicrobial susceptibility test and proved to be sufficient to kill several ml of bacterial broth during the time of the release measurements. It was shown that the soaking time does not affect the release rate and the results suggest that it is possible to develop implants with the option to add antibiotics to their surface at the site of surgery by a simple soaking method.
Visualization of Invasion into the Body and Internal Diffusion of Nanoparticles
Authors: Watari Fumio , Abe Shigeaki , Rosca I.D. , Yokoyama Atsuro , Uo Motohiro , Akasaka T. , Takashi N. , Totsuka Y. , Hirata E. , Matsuoka M. , Ishikawa K. , Itoh S. , Yawaka Y.
Published: March 2009

Nanoparticles may invade directly into the internal body through the respiratory or digestive system and diffuse inside body. The behavior of nanoparticles in the internal body is also essential to comprehend for the realization of DDS. Thus it is necessary to reveal the internal dynamics for the proper treatments and biomedical applications of nanoparticles. In the present study the plural methods with different principles such as X-ray scanning analytical microscope (XSAM), MRI and Fluorescent microscopy were applied to enable the observation of the internal diffusion of micro/nanoparticles in the (1) whole body level, (2) inner organ level and (3) tissue and intracellular level. Chemical analysis was also done by ICP-AES for organs and compared with the results of XSAM mapping.
Study and Characterization of Powders Nanocomposites Calcium Phosphate/Silica-Gel (SiO2n) Obtained from Attrition Milling: For Biomedical Applications
Authors: Brandão Rodrigo , Pupio Fernando , Camargo Nelson Heriberto A. , Gemelli E.
Published: March 2009

The bioceramics nanostructured have made important characteristics in biomedical applications, especially the calcium phosphate ceramics. The aim of this work is synthesis and characterization of calcium phosphate and nanocomposites powders, the method of dissolution of CaO in liquid medium, precipitation and formation of bone calcium phosphate matrix, and nanocomposites by adding the solution of phosphoric acid (H3PO4). The nanocomposites powders were synthesized using as strengthening silica gel nanometer (20nm) at concentrations of 1%, 2%, 3% and 5% by volume and subjected to heat treatment to 900°C for 2 hours, seeking obtained HA (Hydroxyapatite). Later the bone matrix of calcium phosphate and nanocomposites powders were subjected from process attrition milling for 2 hours, by way of comparison. The studies characterizations were conducted through the technique of X-ray diffraction, scanning electron microscopy (SEM) and dilatometric test.
Synthesis and Characterization of Nanostructured Ceramic Powders of Calcium Phosphate and Hydroxyapatite for Dental Applications
Authors: Camargo Nelson Heriberto A. , de Lima S. , Souza Julio C.P. , de Aguiar Juliana F. , Gemelli E. , Meier Márcia M. , Silva Vanessa E. , Mittelstädt Friedrich G.
Published: March 2009

In the last decades many investigations have been oriented toward the development of nanostructured biomaterials such as calcium phosphate ceramics, particularly those composed of stoicheiometric hydroxyapatite (Ca10(PO4)6(OH)2) and a-and β- tricalcium phosphate (Ca3(PO4)2), which present chemical and crystallographic similarities with hard tissues (bones and teeth). Because of these characteristics, these materials can be used for reconstitution and regeneration of bone tissues. The odontological and biomedical applications are still limited due to their brittle behaviour. This study was focused in the synthesis and characterization of a bone matrix of calcium phosphate (β-TCP) and hydroxyapatite (HAP-101 e HAp-201). The results presented here are related to the morphological characterization of nanostructured powders from scanning electron microscopy viewpoint. X-ray diffraction was used to identifier the present phases in the powders and the infrared spectrometry (FTIR) was used to analyse OH bonds from hydroxyapatite and PO4 from calcium phosphates.
A Novel Bone Scaffolds Based on Hyperbranched Polyglycerol Fibers Filled with Hydroxyapatite Nanoparticles: In Vitro Cell Response
Authors: de Queiroz Alvaro Antonio Alencar , Bressiani José Carlos , Bressiani Ana Helena A. , Higa Olga Z. , Abraham Gustavo Abel
Published: March 2009

A novel bone scaffolding material was successfully fabricated by electrospinning from hyperbranched polyglycerol (HPGL) solutions containing nanoparticles of hydroxyapatite (HA). The potential use of the electrospun fibrous HPGL-HA scaffolds for bone regeneration was evaluated in vitro with human osteoblasts in terms of alkaline phosphatase (ALP) activity of the cells that were cultured directly on the scaffolds. The results were compared with those on corresponding HPLG-HA solution-cast film scaffolds. It was found that all of the fibrous scaffolds promoted much better adhesion and proliferation of cells than the corresponding film scaffolds.
Insulin Adsorption by Hydroxyapatite
Authors: Mavropoulos Elena , da Rocha Nilce C.C. , Costa Andrea Machado , Rocha-Leão Maria Helena M. , Mello Alexandre , Rossi Antonella M.
Published: March 2009

In this study, the insulin adsorption ability by synthetic hydroxyapatite was investigated. Hydroxyapatite before thermal treatment and heated at 900°C and 1100°C were incubated in a solution containing 32 mg insulin/gHA. Adsorption and desorption experiments were carried out at 37°C under constant and slowly stirring. From FTIR results it was observed that insulin was tightly attached to HA surface after 96 hours adsorption experiment. Thermal pre-treatment on HA samples had no effect on insulin adsorption. However, protein desorption was more pronounced on samples not submitted to thermal treatment.
Influence of Strontium Ferrite on Properties of 0-3 Cement-Based Piezoelectric Composites
Authors: Huang Shi Feng , Li Xue , Liu Fu Tian , Liu Ya Mei , Cheng Xin , Li Zong Jin
Published: March 2009

0-3 cement based piezoelectric composites were fabricated using sulphoaluminate cement as matrix by compressing technique method. The effects of strontium ferrite content on the piezoelectric properties, dielectric properties and acoustic impedance of the composites were studied. The results show that the piezoelectric strain constant d33 and piezoelectric voltage constant g33 of the composites increase gradually with increaing strontium ferrite content. When the strontium ferrite mass fraction is 0.4%, both of the piezoelectric strain constant d33 and piezoelectric voltage constant g33 of the composite have the maximum value, and the values are 16.6pC•N-1 and 31.4mV•m•N-1, which are 35% and 19% larger than that of the composite without strontium ferrite doped, respectively. With the strontium ferrite content increase, both of the dielectric constant εr and the dielectric loss tanδ of the composites increase. With the addition of strontium ferrite the acoustic impedance Z increases, but there is no obvious relation between the strontium ferrite content and Z.
Mathematical Modeling of the Pessimum Action of Chlorides on the Extent of Delayed Ettringite Formation. Part 1: Formulation
Authors: Mulongo Pelmane Lenge , Ekolu Stephen
Published: March 2009

Internal sulfate ions are the main cause of delayed ettringite formation, which leads to expansive damage of cement concretes. On the other hand, the exposure of cementitious systems to chloride ions causes corrosion of reinforcement bars that finally seriously shortens the service life of reinforced concrete structures. It has been found that, when concomitantly present in cementitious systems, chlorides interact with sulfate ions. Particularly, for a given concentration of sulfate ions present, low to moderate concentrations of chloride ions bring about serious deterioration of concretes due to high amount of ettringite formed, while higher contents of chlorides tend to reduce and even completely eliminate ettringite formation. The objective of the present project is to mathematically formulate the interaction between chloride and sulfate ions in cementitious materials. Such knowledge is useful for accurate consideration of the action of chlorides on concretes used in sea environments, thus predicting more precisely their service life (this being a far important step in design).
Sulfate-Ion Diffusion Regularity and Reaction Mechanism of Sodium Sulfate Attack on Carbonized Concrete
Authors: Li Xiao Ke , Zhao Shun Bo , Shi Chang Cheng
Published: March 2009

The experiment has been carried out to study the sodium sulfate attack on carbonized concrete. The concrete specimens with strength grade of C50 were first carbonized for 28d in the carbonation box after standard curing, and then immersed into the sodium sulfate solutions of three different concentrations. When the immersed time were up to 30d, 90d, 180d, 270d and 360d, the sulfate-ion concentrations of every layer from the surface to the inside of concrete specimen were measured by the chemical titration method. Based on the test results, the sulfate-ion diffusion regularity and the reaction mechanism of carbonized concrete are analyzed. It can be concluded that the sulfate-ion diffusion regularity and the reaction mechanism of carbonized concrete is completely different from that of un-carbonized concrete, the diffusion of sulfate-ion occupies advantage in the pore water of carbonized concrete, which increases the depth of concrete specimen attacked by sulfate solution.
Microstructure Analysis of the Rust Developing at Steel-Concrete Interface
Authors: Dong Rong Zhen , Wei Jun , Zhou Xi Wu
Published: March 2009

The rust distribution and the crack expansion in the deteriorated concrete were studied through the macroscopic and microcosmic method. The results show that the corrosion of steel bar in the concrete is non-uniform even though by Galvanostatic Method. The crack appears earlier and expands quicker at the thin concrete cover than others side and the short crack filled by the rust is found near by the steel bar and converges the main crack. The distribution, composition and the developing of the rust at steel-concrete interface were studied by the microscopic methods of BSE, EDAX and Raman Microscope. By these methods, the rust distributes inhomogeneous and the ion element area was divided into zones evidently. From concrete to steel bar, the rust in turn is: initial rust zone, the mixture area of the rust and mortar about 20-50 μm in width and main containing the goethite (FeOOH); the secondary rust zone, high density area of ion element and about 10-20μm in width and being the mixture of hematite（Fe2O3）and magnetite(Fe3O4); the final rust zone, similar as the initial rust and being the mixture of hematite(Fe2O3)and goethite(FeOOH). According to the electrochemistry principle, the forming process of rust does not follow the iron oxidation procedure entirely but form middle production under the special situation of the condition interior concrete and the electric field outside. The extrusion action of concrete around steel bar makes the rust compressed and metamorphic and the secondary rust forming. So the process and the final state of this special corrosion production are the key parameters leading to the deterioration of concrete.
Experimental Study on Fiber Reinforced Concrete
Authors: Wei Ming Hui , Liu Yi Ping , Tang Li Qun , Huang Xiao Qing
Published: March 2009

Flexure behaviors of plain concrete (PC), steel fiber reinforced concrete (SFRC), polymer modified concrete (PMC), steel fiber reinforced and polymer modified concrete (SFRPMC) and hybrid fiber reinforced concrete (HFRC) with steel fiber and polymer fiber are studied in this paper, flexure tests were carried out and flexure strengths of the five different materials with different mixture ratios were measured and compared. Flexure ductility of PC, PMC, SFRC, and SFRPMC were calculated and compared. In addition, considering performance and cost estimation comprehensively, HFRC is recommended, preliminary tests show that HFRC may be one of the potential materials for bridge pavement.
Workability and Strength Characteristics of High Performance Concrete with Steel Slag Admixture
Authors: Li Yun Feng , Wang Ling , Yao Yan , Lin Hui
Published: March 2009

Workability, mechanical properties and durability of concrete can be greatly improved with the advanced mineral admixtures such as steel slag powder. The workability and mechanical properties of steel slag concrete with different types of steel slag and different dosage of admixtures are studied. The experimental results showed the effect of steel slag powder on concrete performance. When compound mineral admixtures with steel slag powder and blast-furnace slag powder are mixed into concrete, the performance of concrete can be improved further due to the synergistic effect and mutual activation.
A Study on Flexural Performance of RC Beam Strengthened with UHTCC for Improved Durability
Authors: Xu Shi Lang , Zhang Xiu Fang , Leung Christopher K.Y.
Published: March 2009

Ultra-high toughness cementitious composite (UHTCC) exhibits the pseudo-hardening feature when subjected to tensile load and has high tensile strain capacity of normally up to 3%. Also, UHTCC has a unique cracking behavior. From cracking up to ultimate tensile strain capacity, the crack width in UHTCC could be still kept below 100m. This paper presents the utilization of UHTCC to replace a layer of concrete surrounding the main flexural reinforcement in ordinary RC beam to improve flexural performance especially beam durability as UHTCC displays high toughness and shows multiple fine cracks. Analytical closed-form formulae for flexural capacity, curvature and deformation of UHTCC/RC composite beam derived based on the elastic beam theory is presented first. Subsequently, experimental results of two groups of different reinforcement ratios of UHTCC/RC beams and control RC beams tested under flexural loading to verify the feasibility of analytical formulae as well as to examine the performance improvement of UHTCC/RC composite beam over the control beam is presented. Moment-curvature curves and load-mid span displacement curves for the tested beams are compared with the theoretical analysis. A good agreement between experimental and analytical results is found. The experimental results show that the use of a layer of UHTCC in RC beams can enhance both flexural capacity and ductility. The improvement is not significant with the increase in reinforcement ratio; however, the maximum crack width under service load even in the case of lightly reinforced beams can be limited within 0.1mm.
Experiment on Freezing and Thawing Durability Characteristics of Recycled Aggregate Concrete
Authors: Zhu Hong Bing , Li Xiu
Published: March 2009

Recycling old concrete as an alternative source for production new concrete can solve the environment produced by old concrete. To make such recycling feasible, the strength and durability of the recycled aggregate concrete (RAC) must be assured. Prepared recycled coarse and fine aggregate using natural concrete specimens produced by compressive strength test of cubic concrete. Prepared recycled aggregate concrete which replacement ratios is 50% and 70%. Processed compressive strength test of cubic RAC specimens. Carried through the test for resistance of concrete to rapid freezing and thawing on both RAC and natural concrete. As a result of the experiment, the strength of the RAC can reach the design strength, however, the index for the resistance of concrete to rapid freezing and thawing depressed to a certainty degree relative to that of common concrete. Replacement ratio of aggregate influenced relative dynamic modulus of elasticity of RAC seriously. The weight change increased as long as the number of freezing and thawing cycles increased, and the weight change increased when replacement ratio elevation. RAC showed a sharp weight loss during the testing period, and reduce the water cement ratio can increase the durability characteristics of RAC. Also, absorption of the recycled aggregate influenced durability properties of RAC badly.
Repairing Bridges in Coastal Area with Ba Bearing Sulphoaluminate Cement
Authors: Cheng Xin , Ye Zheng Mao , Chang Jun , Lu Ling Chao
Published: March 2009

In coastal areas, corrosion has been found in bridge piers made of Portland cement concrete. In an trail to protect the piers from further damages, Ba bearing sulphoaluminate cement concrete was tested as the repairing layers. It is showed that the Ba bearing sulphoaluminate cement concrete has a lower porosity and a more compact structure than Portland cement concrete under the same conditions, and consequently, better performances, such as high strength and corrosive resistance both in lab and real corrosive environments. Stimulating experiments indicate that Ba bearing sulphoaluminate cement is more suitable for repairing bridges in coastal area.
Experimental Studies on Axially Loaded Concrete Columns Confined by Different Materials
Authors: Guo Yong Chang , Huang Pei Yan , Yang Yang , Li Li Juan
Published: March 2009

The improvement of the load carrying capacity of concrete columns under a triaxial compressive stress results from the strain restriction. Under a triaxial stress state, the capacity of the deformation of concrete is greatly decreased with the increase of the side compression. Therefore, confining the deformation in the lateral orientation is an effective way to improve the strength and ductility of concrete columns. This paper carried out an experimental investigation on axially loaded normal strength concrete columns confined by 10 different types of materials, including steel tube, glass fiber confined steel tube (GFRP), PVC tube, carbon fiber confined PVC tube (CFRP), glass fiber confined PVC tube (GFRP), CFRP, GFRP, polyethylene (PE), PE hybrid CFRP and PE hybrid GFRP. The deformation, macroscopical deformation characters, failure mechanism and failure modes are studied in this paper. The ultimate bearing capacity of these 10 types of confined concrete columns and the influences of the confining materials on the ultimate bearing capacity are obtained. The advantages and disadvantages of these 10 types of confining methods are compared.
Reliability-Based Shear Design for Reinforced Concrete Beams with U-Wrap FRP Strengthening
Authors: He Zheng , Shang Miao Hong , Li Xiao Ming
Published: March 2009

The resistance factor in the draft version of Chinese Technical code for the application of fiber reinforced polymers in civil engineering for the shear-resistant design of reinforced concrete beams with U-wrap FRP strengthening is assessed from the probabilistic standpoint. The assessment using a resistance-factor-related computational uncertainty factor indicates that the average reliability indexes, for either unstrengthening or strengthening, increases at a slowing rate as load effect ratio increases from 0.10 to 2.5, and that the average reliability indexes for strengthened beams would dramatically decrease up to 19.2%~28.5% with the resistance factor specified in the code for U-wrap strengthening. A so-called reliability strengthening ratio is introduced to evaluate the change in average reliability index before and after strengthening with different resistance factors. A parametric study on this factor shows that if the reliability level in strengthened reinforced concrete beams is kept to be consistency with their corresponding unstrengthened beams, a value of 0.67 could be applied. The proposed relationship between reliability strengthening ratio and the resistance factor could be also used in personalized designs.
The New Italian Code for Seismic Isolation of R.C. Constructions and Application to an Existing Bridge for Seismic Upgrading with a Hybrid Isolation-Dissipation Device
Authors: Monti Giorgio
Published: March 2009

In this paper the new Italian seismic code issued in January 2008 is presented, with particular reference to the ample section devoted to constructions built with isolation and energy dissipation systems. Such attention is justified by the undisputed effectiveness of this design approach and by its increasing diffusion in the professional community. The code is based on Eurocode 8 [1], though resulting more synthetic and easier to use. During the last years of evolution, the code has significantly contributed to the development of new concepts in seismic isolation, such as the hybrid biaxial isolating/dissipating device here presented, obtained from parallel coupling of two different types of device: one mechanical, which realizes the necessary dissipation, and one elastomeric, which has the scope, beyond that of sustaining the vertical load, of reducing the deck residual displacement at the end of the seismic action. An application is shown of a seismically retrofitted highway bridge, in order to show the effectiveness of this device, both during, in terms of isolation, and at the end of the seismic event, in terms of residual displacements. For the sake of comparison, the same bridge is analyzed with different types of isolation techniques.
Behaviors of Concrete Beam Prestressed with External CFRP Tendons
Authors: Li Hong Fang , Gong Chang , Fang Zhi
Published: March 2009

The purpose of present paper is to study the flexural behaviors of concrete T-beams prestressed with external carbon fiber reinforced polymer(CFRP) tendons. Tests were carried out on 5 beams under four-point load, of which four beams were reinforced with hybrid both external CFRP tendons and internal steel rebars and another one only reinforced with internal steel rebars. Such parameters as the different initial loading states at external CFRP tendon jacking and different jacking stress in tendon were considered in experiment. A program was developed to predict the behaviors of those beams prestressed with externally prestressed tendons and the parametric study was conducted using the program. The predicted results from the program were in good agreement with the test results. Such parameters as jacking stress, elastic modulus of external tendons, configuration of deviators and ratio of span to effective depth of beam were chosen as primary analytical factors for the study on the flexural behaviors of beams prestressed with external tendons. The initial loading state on the beam before tendon jacking has no significant influence on the ultimate loading capacity and deflection.
Study on Evaluation Method of High-Rise Building Performance by Equivalent Single Degree of Freedom System
Authors: Liang Xing Wen , Xin Li , Tong Yue Sheng
Published: March 2009

A performance evaluation method of high-rise buildings is presented, by means of capacity spectra method which allows for higher mode effects. The multi-degree-of-freedom system (MDOF) of each mode is transformed into equivalent single-degree-of-freedom (ESDOF) system, and the ESDOF system is supposed to be elastic perfectly plastic. In elastic range, the equivalent displacement of ESDOF system for each mode is deduced by displacement response spectra based on the natural period, and the structural lateral elastic displacement of each mode could be determined by the corresponding equivalent displacement and mode shape. In inelastic range, according to capacity spectra method, the relationships among demand curve, capacity curve and ductility coefficient are built. The structural performance under moderate or major earthquake is determined by iteration method. The paper illustrates the application of the proposed procedure with an example and attempts to prove its feasibility by nonlinear time-history analysis.
Anti-Seismic Behavior of Innovatory RC Frame Subjected to Severe Earthquake Action
Authors: Wang Xiu Li , Li Xiao Dong , Li Tao
Published: March 2009

The anti-seismic behavior of RC frame with buckling restrained braces (BRBs) subjected to severe earthquake action in seismic region was investigated in this paper. A design process of the buckling restrained braces used for stiffness-deficiency concrete frame structures was given, the design of the buckling restrained braces was conducted for a common frame structure, the layout of these braces in it was given by taking an actual engineering for illustrations, and the static analysis and time-history dynamic analysis were also performed. The results of computation showed that the use of buckling restrained braces has led to several functional improvements, such as the increase in structure stiffness, reduction of story displacement, and improved energy dissipation ability when compared with the frame without such braces. Analysis results showed further that RC frame with BRBs could absorb and dissipate seismic energy more effectively, improving anti-seismic performance of the framed structure.
Use of CO2 as an Accelerated Curing Agent for Concrete Blocks
Authors: Shi Cai Jun , Zou Qing Yan
Published: March 2009

In this project, a process was developed to cure concrete masonry blocks using CO2. It was found that the strength of concrete mixtures for block manufacture after CO2 curing was close to that after conventional steam curing. A dry pre-conditioning before CO2 curing was very critical to achieve high degree of CO2 curing. The specimen pre-conditioned in the moist environment hydrates more than those pre-conditioned in the dry environment during the pre-conditioning period. However, much less CaCO3 formed in the former that that in the latter after the CO2 curing. Thus, the CO2 curing is mainly contributed by the reactions between CO2 gas and cement clink minerals.
Flexural Stiffness of Steel-Prestressed Concrete Composite Beam
Authors: Zhou An
Published: March 2009

For continuous composite beams that in normal working stage, due to concrete cracks at negative moment region are restricted by transverse tendon reinforcements at the slab, it would be reasonable to consider concrete contribution to the bending capacity of such composite beams. Based on this, a variable stiffness method is proposed in this paper to calculate the composite beam deflection. Before concrete slab cracks, the flexural stiffness (the maximum value) is calculated according to the reduced transformed beam section, with the consideration of concrete contribution; After concrete cracks, this stiffness value will be decreased as per the increase of the concrete crack, and at final stage, when concrete contribution to the flexural stiffness reach zero, the stiffness value reach it’s minimum value. The loads capacity at such maximum and minimum stiffness values could be considered as the beam capacity before concrete cracking as per current code, and the elastic moment capacity after concrete cracking respectively, while the stiffness between these maximum and minimum values could be determined by linear interpolation. The bending stiffness derived from this method has a higher precision than the method presented in current China specification in which the concrete contribution is totally neglected. Especially, this procedure would be more useful for those prestressed concrete composite beams, as they have higher crack- resistance capability.