bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of SHS-Si3N4 in LSCPM
Authors: Ge Chang Chun , Shen Wei Ping , Wang Fei
Published: March 2009

Since 1990, Ge and his earlier and present groups in LSCPM have made great efforts to investigate the Self-propagating High-temperature Synthesis (SHS) of Si-N2 gas-solid system including the SHS process control and its thermodynamics, structural macrokinetics and formation mechanism of SHS-Si3N4. In this presentation, some results that were firstly reported in the world are reviewed and new progress in recent years is reported.
The Influence of Nanosized Leucite on Dental Porcelain Properties
Authors: Yang Jin Ping , Wu Jian Qing , Rao Ping Gen , Xin Chong Fei , Chen Dong Dan
Published: March 2009

The influence of leucite on dental porcelain properties is investigated in this paper. The nanosized leucite powder prepared by sol-gel method was added into a low-fusing temperature frit to fabricate dental porcelain fused to metal. The porcelains with different leucite contents were sintered at the temperatures ranging from 780° to 900°C. The flexural strength and the thermal expansion coefficient (TEC) of the dental porcelain containing leucite particles are evaluated. The micro- structure and phases of the porcelain are characterized and the mechanism that nanosized leucite particles strengthening the porcelain is discussed.
Thermoelectric Performances of ZrNiSn/C60 Composite
Authors: Huang Xiang Yang , Chen Li Dong , Shi X. , Zhou Min , Xu Z.
Published: March 2009

The ZrNiSn/C60 thermoelectric composite was prepared by a spark plasma sintering (SPS)technique. The obtained sample was fully dense and homogeneous. Slices of the sample were characterized by electrical resistivity, Seebeck coefficient and thermal conductivity up to 850K. It was shown that the composite has a higher electrical conductivity, a lower Seebeck coefficient and a
higher thermal conductivity than the ZrNiSn matrix alloy. XRD pattern and EPMA analysis of the composite revealed that the C60 nano particles reacted with ZrNiSn matrix to form ZrC inclusions.
Electric Properties of Ti3SiC2 at High Frequency Alternating Current
Authors: Wang Chang An , Tang Ke , Huang Yong
Published: March 2009

Bulk Ti3SiC2 material with 95 wt% of purity was synthesized by hot pressing from Ti, SiC and graphite powders. This work focuses on the electric properties of Ti3SiC2 at high frequency alternating current using a specific clamp device. The result shows that Ti3SiC2 exhibits an electric property of inductance (the order of magnitude is about 10-8 H at 1 ~ 40 MHz), which indicates that Ti3SiC2 shows a stronger electric property of metal rather than that of common ceramics. In this study, the equation to calculate the external inductance of nonferromagnetic metal is also applicable to Ti3SiC2 material at high frequency.
Toughening of Ceramic Composite Designed by Silica-Based Transformation Weakening Interphases
Authors: Lee Sang Jin , Lee Chung Hyo , Hwang Jong Hee
Published: March 2009

A new concept for achieving graceful failure in oxide composites is introduced. It is based on crack deflection in a weak interphase between a matrix and reinforcement (e.g. fiber), or in a laminated composite. The interphase can be phase transformation weakened by volume contraction and/or unit cell shape change. Microcracking induced by a displacive, crystallographic phase transformation in silica-based interphases resulted in increase in the toughness of the bulk composites. In the present study, mullite/cordierite laminates with b®a-cristobalite (SiO2) transformation weakened interphase, and alumina matrix fibrous monolith with metastable hexacelsian (BaAl2Si2O8) interphases were investigated for interphase debonding behavior. In mechanical test, the laminates showed step-wise load drop behavior dependent on a grain size of b-cristobalite. In particular, in the fibrous monolith design, the load-deflection curve showed unusual plastic-like behavior with reasonable work of fracture.
Controlled Release Technology Suppresses the Progression of Disseminated Pancreatic Cancer Cells
Authors: Kushibiki T. , Matsumoto K. , Nakamura T. , Tabata Yasuhiko
Published: March 2009

NK4, composed of the NH2-terminal hairpin and subsequent four-kringle domains of hepatocyte growth factor (HGF), acts as a potent angiogenesis inhibitor. This study is an investigation to evaluate the feasibility of controlled release of NK4 plasmid DNA in suppressing tumor growth. Controlled release by a biodegradable hydrogel enabled the NK4 plasmid DNA to enhance the tumor suppression effects.
Biodegradable microspheres of cationized gelatin were prepared for the controlled release of a NK4 plasmid DNA. The cationized gelatin microspheres incorporating NK4 plasmid DNA were subcutaneously injected to tumor-bearing mice to evaluate the suppressive effects on tumor angiogenesis and growth. The cationized gelatin microspheres incorporating NK4 plasmid DNA could release over 28 days. When the cationized gelatin microspheres incorporating NK4 plasmid DNA were injected into the subcutaneous tissue of mice intraperitoneally inoculated with pancreatic cancer cells, their survival time period was prolonged. Tumor growth was suppressed to a significantly greater extent than free NK4 plasmid DNA. The controlled release of NK4 plasmid DNA suppressed angiogenesis and increased cell apoptosis in the tumor tissue, while it enhanced and prolonged the serum level of NK4 protein. We conclude that the controlled release technology was promising to enhance the tumor suppression effects of NK4 plasmid DNA.
Formulation and Characterization of Poly-D, L-Lactic Acid Nanoparticles Containing Daunorubicin
Authors: Cao Rui Rui , Zhang Sheng Min , Luo Q.M. , Liang X.H. , Liu J. , Zhou W.
Published: March 2009

The regular spherical poly-D, L-lactic acid (PDLLA) nanoparticles containing DNR are produced using a double-emulsion solvent evaporation process. The products morphology is characterized by a laser light-scattering particle size analyzer and scanning electron microscopy. Results show a mean diameter in 546.9 nm with narrow size distribution and homogeneous particle production. The encapsulation efficiency is evaluated by UV spectra. The results indicate that drug contents and loading efficiency are 14.34% and 72.9% respectively, and the drug release profile shows a biphasic phenomenon.
Cytocompatibility Testing of Hydroxyapatite/Collagen Composite Cross-Linked with Glutaraldehyde
Authors: Cao H.D. , Tan Yan Fei , Lin Xiao Yan , Fan Hong Song , Zhang Xing Dong
Published: March 2009

Glutaraldehyde was increasingly used to improve the stability of the collagen-based biomaterials as cross-linking. To investigate in vitro cytotoxicity of Hydroxyapatite/Collagen (HA/COL) composite with glutaraldehyde (GA) as cross-link reagent, which was abbreviated as cHA/COL, the mouse fibroblasts L929 cell was selected. The method of MTT colorimetric assay was adopted to evaluate the availability of cells. After cultured for 24h、 48h, the attachment and morphology of L929 cell on the surface of this material were observed by scanning electron microscopy (SEM) and fluorescent microscopy. MTT analysis indicated L929 cells cultured on cHA/COL had a perfect growth capacity. Cells proliferated well and cell colonization was observed on the materials by scanning electron microscopy and fluorescent microscopy. It demonstrated that cHA/COL composite exhibited good cytocompatibility and might be suitable as bone substitutes. The result provided the evidence for further animal experiment in vivo.
Enhanced Biological and Mechanical Properties of Artificial Dermis Prepared Using a Perfusion Culture System
Authors: Seol Dong Lim , Kim Hyeong In , Lee Woo Jung , Jang Won Hee , Kim Jeong Koo , Lee Sung Jae , Yang Young Il
Published: March 2009

A culture system that is capable of providing even and uniform distribution and
deposition of cells and extracellular matrix (ECM) is desired to enhance biological functions of the tissue-engineered artificial dermis (TEADs). For this purpose, we have developed a perfusion culture system that offers uniform exchange of nutrients and gases along the scaffold. Viability and effectiveness of the system were investigated by comparing biological and mechanical properties of TEADs. Results showed that the TEADs constructed by the perfusion culture system revealed significantly increased cell growth, ECM synthesis, and elastic modulus compared to those by the conventional static culture system. In addition, histological findings indicated that cells were more evenly distributed and ECM deposition increased in TEADs with the perfusion culture system. Therefore, it can be suggested that the perfusion culture system can constitute a more promising
approach for constructing the TEADs.
Mechanical Behavior of PLA/HA Composite in Simulated Physiological Environment
Authors: Wong Siuming , Wu Jing Shen , Leng Yang
Published: March 2009

Effects of bio-degradation on the mechanical properties of polylactic acid
(PLA)/hydroxyapatite (HA) were evaluated using a newly designed three-point bending fixture in SBF chamber. The composite was found to be ductile and insensitive to cracks, which is totally different from its brittle behavior observed in conventional tests, in which the degraded samples are tested in air at room temperature. Initial bending modulus and strength of PLA/HA composite were 1.2 GPa and 43 MPa, respectively, which were lower than those tested under room conditions. After two weeks of immersion in vitro, both bending modulus and strength decreased by 40% and 57%, respectively. Their degradation rates were both higher than those in reports of previous researches. This work indicates the importance of evaluating mechanical behavior in simulated body environment.
Bone Induction by Controlled Release of BMP-2 from a Biodegradable Hydrogel in Various Animal Species - From Mouse to Non-Human Primate -
Authors: Yamamoto Masaya , Takahashi Yoshitake , Tabata Yasuhiko
Published: March 2009

The objective of this study is to examine feasibility of biodegradable gelatin
hydrogels incorporating bone morphogenetic protein (BMP)-2 in inducing bone regeneration at a bone defect of non-human primates and rabbits considering their BMP-2 release profiles. As a result, controlled release by the hydrogel system enabled BMP-2 to induce successful bone regeneration in non-human primates even at the BMP-2 dose as low as that for rabbit case (0.034 mg of BMP-2/cm3 of hydrogel).
Experimental Study on the Osteoinduction of Calcium Phosphate Biomaterials In Vivo and the Capability of Supporting Osteoblast Proliferation In Vitro
Authors: Bao C.Y. , Li P. , Tan Yan Fei , Cao Y. , Lin Xiao Yan , Deng Chun Lin , Li Xu Dong , Ou Guo Min , Chen W.C. , Gong P. , Fan Hong Song , Zhang Xing Dong
Published: March 2009

The purpose of this study was to evaluate the response of osteoblasts to calcium phosphate with different surface modification, and to evaluate the osteoinductive capabilities of these biomaterials. 60HA/40α-TCP ceramics sintered at 1250oC was applied in this study. A ceramic cylinder with F5mm×8mm and slice with F10mm×1mm were prepared respectively. One third of the ceramics was used to form bone-like apatite (BLA), and the surface of another one third was modified with collagen. Osteoblasts (1×106/ml) were co-cultured with the three kinds of thin slices for 12h, 24h and 48h. SEM observation was applied to evaluate whether the surface modification and BLA formation could affect the attachment and proliferation of osteoblast in vitro. The three kinds of cylinder samples were implanted in dog muscle to evaluate their differences in osteoinduction. Cells grew in multi-layers and attached to the surface and proliferated well in the collagen and HA/TCP group. In the untreated and BLA precipitated groups, cells did not attach to the surface well. Osteoinduction was good in the BLA precipitated group and the amount of bone formed was higher; in the untreated group and collagen-treated group, no bone formation was observed in the tested period. This result indicated that the scaffold used in cell-materials composites in vitro and that in osteoinductive material based tissue engineering in vivo was not same.
Bioactivity of Plasma-Sprayed Diopside Coating In Vitro
Authors: Xue Wei Chang , Ding Chuan Xian , Cao Cong , Dong Yuqi
Published: March 2009

A new bioceramic coating based on diopside was prepared by plasma spraying. The
surface and cross-section microstructure of the coating were examined by scanning electron microscopy. The thermal expansion coefficient of the diopside coating measured by a dilatometer adapted to that of titanium alloy. The bond strength of the coating was about 32.5 MPa, which is higher than that of HA coatings used in orthopedics and dentistry. The bioactivity of diopside coating was evaluated in vitro. After 15 days soaking in simulated body fluid, an apatite layer was
formed on the surface of the coating. The cytocompatibility was investigated by studying the behaviour of human osteoblast cultured directly onto the surface of the coating. MTT assay was performed to assess the influence of the coating on cell proliferation. The morphologies of the cell were observed by SEM after incubation for 1 and 7 days. The results obtained indicated that plasma sprayed diopside coating may be a suitable candidate for bone and dental implant.
Mechanical Properties and Antithrombogenecity of Blend Membrane of Silk Fibroin
Authors: Tang Yin , Cao Chuan Bao , Ma Xilan , Li Jing Hua , Zhu He Sun
Published: March 2009

The silk fibroin blend membranes were prepared by adding a small amount of poly (vinyl alcohol) (PVA) and heparin. By controlling the preparation conditions, the tensile strength and elongation at break reached to 8.86 MPa and 231.8%, respectively. Meanwhile the in vitro antithrombogenecity significant increased. The clot times (APTT, TT and PT) all exceeded the measurement limit of clot detection instrument. It is expectable using these natural materials to prepare small caliber vessel.
Novel Prosthesis Using Silk Fibroin for Small Caliber Vascular
Authors: Ma Xilan , Cao Chuan Bao , Li Jing Hua , Zhu He Sun
Published: March 2009

A novel prosthesis using silk fibroin with blending heparin and sulfonated silk fibroin was studied. Anticoagulation activities of heparin/silk fibroin and sulfonated silk fibroin/silk fibroin vascular and mechanical property results showed that heparin/silk fibroin and sulfonated silk fibroin/silk fibroin vascular could meet the requirement of small caliber grafts. This study indicated that silk fibroin could be used for developing tissue engineering biological vascular grafts that could use for human coronary or low extremity artery bypasses.
Radiation-Induced Graft Polymerization of Maleic Anhydride onto Poly-β-Hydroxybutyrate
Authors: Ye Herong , Yang Dongzhi , Hu Ping , Zhang Feng Bo , Qi Qinglei
Published: March 2009

This paper focuses on an effective way to improve the thermostability of
poly-β-hydroxybutyrate (PHB). Maleic anhydride (MA) is grafted onto PHB by 60Co γ of radiation. The spectra of both 1HNMR and 13CNMR were investigated following the radiation-induced polymerization. The results are consistent with successful grafting of the MA monomer onto the PHB, with a low graft degree. The graft degree and viscosity-average molecular weight Mηof the radiated samples were also investigated. The results observed through TGA demonstrate that
thermostability has been measurably improved with the introduction of MA groups. These significant results suggest that wide commercial application of PHB may be possible.
Vascular Tissue Regeneration of the Hybrid ePTFE Graft for Adult Patients
Authors: Noh In Sup
Published: March 2009

Vascular Tissue engineering has drawn high interest due to its high demand in its vascular graft applications. We tissue-engineered a hybrid vascular graft consisting of tissues layers and non-biodegradable ePTFE by in vitro cell culture. Tissue formation was obtained by culturing vascular smooth muscle cells on the biodegradable polylactide scaffolds on the ePTFE surfaces. The fabricated hybrid ePTFE graft consisted of three layers, i.e. two biodegradable polylactide
layers and a non-biodegradable ePTFE layer. The biodegradable layer was fabricated to have a porous structure with 30-60 µm pore sizes. Connection of biodegradable layers and ePTFE was obtained by filtering the polylactide solution through the porous ePTFE wall. For a better tissue formation coating of gelatin was performed on the luminal polylactide scaffolds. The generated tissues replaced the biodegradable layers on both inside and outside surfaces of the ePTFE.
Rheological Properties and Injectability of a Calcium Phosphate Bone Substitute Material
Authors: Wang H. , Wang Xiao Ping , Ye Jian Dong , Wang Ying Jun , Rao Ping Gen
Published: March 2009

A calcium phosphate bone substitute material was prepared and its rheological behavior and injectability were studied in this work. The effects of temperature, L/P ratio and adjuvant on the rheological properties and injectability of the pastes were discussed. The results show that the calcium phosphate bone substitute material is injectable with good fluidity and is suitable for the clinical applications. The rheological behavior and injectability of the bone substitute material can be improved by adding adjuvants and optimizing L/P ratio.
Fabrication of Fully-Porous and Porous-Surfaced Ti-6Al-4V Implants by Electro-Discharge-Sintering of Spherical Ti-6Al-4V Powders and Their Osseointegration Ability
Authors: Lee W.H. , An Y.B. , Oh N.H. , Choen Y.W. , Kwon J.J. , Lee Kwon Yong
Published: March 2009

We have first fabricated porous-coated Ti alloy dental implants with a wide range of
porosity by electro-discharging-sintering of spherical Ti-6Al-4V powders. The basic physical properties of EDS implants have been evaluated. The dependence of mechanical properties of each kind of implant such as micro-hardness and compressive strength has been also analyzed. The solid core and neck sizes between powders on porous layer generally increase with both input energy and capacitance. On the other hand, the pore size decreases with both input energy and
capacitance. The micro-hardness analyses at various locations such as solid core and powders on porous layer show quietly consistent values. The compressive strengths of each implant are in the range of 39 and 452 MPa which depends on the input energy. In-vivo animal experiments showed that all the implants fabricated by current method were biocompatible and support rapid and perfect osseointegration in 2 weeks.
The Influence of Albumin on the Electrochemical Behaviour of Commercial Titanium
Authors: Aeimbhu Areeya , Castle James E. , Singjai Pisith
Published: March 2009

The purpose of this study was to investigate the effect of albumin on the potentiodynamic anodic polarisation of commercially available pure titanium (CP Ti). The polarisation was performed starting at 1200 mV and terminating at 3500 mV vs. Saturated Calomel Electrode (SCE) in 3.5wt% NaCl with and without additions of egg albumin. The surfaces of untreated and treated disks by terminating at 1400 mV and at 1800 mV were characterised using the N1s peak via X-ray Photoelectron Spectroscopy (XPS). It was found that the adsorption of albumin obstructed the
passivation and that the corrosion rate in transpassive region was significantly increased.
Physico-Chemical and Biological Evaluations of Biomedical Polyethylene after YAG-LASER Irradiation
Authors: Blanchemain N. , Mayer G. , Traisnel M. , Setti Y. , Hildebrand H.F.
Published: March 2009

PE is manufactured by Transysteme with the method of thermocompression of PE powder. This company irradiates PE by YAG LASER. We compared the physical behavior of both samples. The DSC reveals a high and similar crystallinity of PE, before and after YAG LASER treatment. Weattability between PE and Li-PE are similar at about 37 mJ/cm². The difference appears with respect to the surface profile and composition: the roughness is 0.20 µm for PE and 0.29µm for Li- PE. XPS reveals many traces of stripping agents on PE. YAG Laser produces a surface cleaning effect. Biological tests reveal a non-toxicity of the polyethylene powder, an improved proliferation and vitality of L132 cells on Li-PE with respect to untreated PE. We have a 4-fold improvement of proliferation and a 2-fold improvement of vitality on Li-PE with respect to PE. As to morphology and cell adhesion behavior, we have no differences between both samples. Thus the irradiation process of PE by YAG LASER improved the biological behaviors of this polymer due to changes in roughness and to surface cleaning.
Preliminary Evaluation of a New Dental Implant Design with Finite Element Analysis
Authors: Wang Xue Jun , Wang R. , Luo J.M. , Chen Ji Yong , Zhang Xing Dong
Published: March 2009

It is important to obtain mechanical coupling between dental implants and bone, because the lack of mechanical coupling may cause bone loss around implants. In this research, a new cylindrical dental implant composed of three parts was designed to offer favored mechanical environment for the bone. A special gap structure changed the means of the stress transmission and decreased the stress in
the cortical bone around the neck of the implant. Through finite element analysis (FEA) of stress distribution in bone around implant-bone interface, the advantages of this new implant (reducing stress concentration in cervical cortex and satisfying varieties of clinical needs) were verified. The peak stress for the new design was about 30 percent less than that of the traditional implant and the flexibility of the design was also confirmed by changing the gap depth and the wall thickness.
Size Effects in Micro- and Nanocarbon Added C/Si3N4 Composite Prepared by Hot Pressing
Authors: Balázsi Csaba , Şahin Filiz Çinar , Addemir O. , Kasztovszky Zsolt , Kövér Zsuzsanna , Wéber Ferenc
Published: March 2009

Silicon nitride based composites have been fabricated by carbon addition. Carbon black nanograins and graphite micrograins were used as second phase additions. Alumina and yttria were used as sintering aids. Mixing of powders was performed in a ball mill and for comparison in a high efficient attritor mill. For sintering the hot pressing technique has been applied. Experiments at 2 MPa uniaxial pressure have been performed. The Si/N mass fraction after sintering were determined by prompt gamma activation analysis (PGAA). The amount of carbon black and graphite introduced in the silicon nitride matrix increased the porosity and decreased the hardness and bending strength of composites. Lower modulus, and lower strength was obtained for composites with carbon black addition in comparison to graphite added samples. The microstructure of composites consisted mainly of alpha and beta silicon nitride. The formation of silicon carbide was observed only at 10 wt% carbon black addition.
Scratchability of Soda-Lime Silica (SLS) Glasses: Dynamic Fracture Analysis
Authors: Le Houérou V. , Sanglebœuf J.-C. , Rouxel Tanguy
Published: March 2009

Grinding and polishing are widely used for glass machining with fine finished
surfaces. These processes result from abrasion due to repeated contacts between hard sliding particles and the glass surface. The study of contact mechanics problem is of fundamental interest to understand the process of material removal in glasses. In order to get insight into this problem, an experimental set up was designed which allows a monotonic loading of the indenter combined with a controlled sliding of the specimen to simulate a slow abrasive machining process. In addition, the experiments are conducted with an in-situ video monitoring that allows for the observation of the different fracture phenomena beneath the indenter. Fracture surfaces were also studied using SEM and AFM for multi-scale
investigation. Fracture analysis was carried on a standard float glass, four different SLS glasses and a fused silica glass. The observed phenomena were discussed in the light of the influence of the normal load and the chemical composition.
Strength and Fractography of High Power Varistors
Authors: Wang Z. , Supancic Peter , Aldrian F. , Schriener A. , Danzer Robert
Published: March 2009

Electroceramic varistors, typically based on ZnO, show a strong non-linear currentvoltage characteristics. Actually they can be considered as electrical isolators below a critical field strength and highly conductive above. These components are used as over voltage protection elements in various fields of electric and automotive industry. In testing and in service high power varistors are loaded with µs-voltage pulses and suffer high mechanical loads due to thermal shock and inertia effects. Therefore the reliability in terms of mechanical strength becomes a crucial mark of quality. In this work the microstructure and the strength of commercial high power varistors of three different producers are presented. By a
subsequent fractographic analysis fracture initiating defects are identified. It is shown, that defects in the microstructure, which result from the processing of the varistor components, play a significant role for the strength of the ceramics and of course also for the service performance of the components.
Fracture Origins in Miniature Silicon Carbide Structures
Authors: Quinn George D. , Sharpe William N. , Beheim Glenn M. , Nemeth Noel N. , Jadaan Osama
Published: March 2009

Direct tension strength tests were conducted on chemical vapor deposited silicon carbide microspecimens. Three types of specimens were used: straight gage section, tapered gage section, and notched gage section. The average strengths and standards deviations were: 0.42 GPa ± 0.13 GPa; 0.47 GPa ± 0.16 GPa; and 0.68 GPa ± 0.19 GPa, respectively. The fracture origins were identified by fractographic analysis and were cracks in large grains next to surface grooves from the deep reactive ion etch (DRIE) process used to fabricate the specimens.
Surface Quality Improvement of Aspheric Pressing Mould Using Parallel Grinding Method
Authors: Zhang Fei Hu , Li L.J. , Dong Shen
Published: March 2009

It is a cost-effective technology to obtain aspheric optics made from optical glass and
other brittle materials using pressing mould. The optical quality of molded optics is determined mostly by the surface quality of the mould, which means poor mould surface with lots of cutter marks will result in adhesion phenomena and error replication between the optics and mould. [1] In this article, a chatter model about parallel grinding system was presented, and the reasons of chatter induced by velocity feed back was analyzed and simulated. By using parallel grinding system
integrated ELID technology, and wheel with greater cross-section radius in rough grinding and constant grinding velocity in fine grinding, the amplitude of cutter marks in the surface of mould was minimized and the quality of the mould surface was improved.
Effects of Ultrasonic Vibration in Truing and Dressing of CBN Grinding Wheel Used for Internal Grinding of Small Holes
Authors: Nomura Mitsuyoshi , Wu Yong Bo , Kato M. , Kuriyagawa Tsunemoto
Published: March 2009

This paper describes an experimental investigation of the effects of ultrasonic vibration in the truing and dressing of the small CBN grinding wheel used for the internal ultrasonic grinding of small holes. In the precision machining of small holes measuring several millimeters in diameter, improvement in the wheel truing accuracy is significantly levels off when using a single diamond dresser or a rotary GC wheel dresser. In the present work, a new truing and dressing technique was proposed, by which the grinding wheel is ultrasonically vibrated in its axial direction during the
truing operation using a rotary GC cup dresser. In order to validate the proposed new technique, experiments were carried out. During experimental operations, the GC cup wheel was traversed along the vitrified CBN grinding wheel axis with an in-feed motion toward the grinding wheel in the wheel radial direction. The influences of the truing parameters on the truing force, the run-out of grinding wheel and the grinding wheel surface properties were investigated. As a result, it was found that
applying ultrasonic vibration to the grinding wheel decreased the truing force by more than 22%, and the run-out of grinding wheel decreased from an original value of 150µm to a final one of less than 0.8µm, while that obtained without ultrasonic vibration was more than 1.1µm. As well, better surface properties of the grinding wheel were obtained by the application of ultrasonic vibration.
Machining Mechanisms of Si Wafers in Mechanochemical Polishing by Soft Abrasives
Authors: Yasunaga Nobuo
Published: March 2009

The mechanism of the mechanochemical polishing of Si wafers with BaCO3, CaCO3 and ZnO abrasives was investigated by polishing experiments carried out in air, O2 and Ar gas environments on dry condition and static heat treatment experiments of mixed powder of BaCO3 and Si with various mixture ratios for analyzing the reaction mechanism at the interface in polishing operation. Results obtained were (1) Si wafers were smoothly and effectively polished with these all mechanochemical abrasive whether O2 gas existed in the surrounding environment or not, (2) Heat
treatment of the mixed powder suggested that oxidation of Si was more actively promoted even when existence of BaCO3 powder was only a little in the mixture and that formation of Ba-Si oxide increased as the mixture ratio of BaCO3 powder to Si powder increased, (3) As the mechanochemical polishing mechanism, two-step reaction process would be the most reasonable, that is, chemical attack of the mechanochemical abrasive for oxidizing the Si surface as the first step and further
chemical reaction to form reaction products between the formed SiO2 and the abrasive as the second step.
Study on the Surface and Subsurface Integrity of Ground Monocrystalline Silicon Wafers
Authors: Kang Ren Ke , Zhang Y.X. , Guo Dong Ming , Jin Zhu Ji
Published: March 2009

Wafer rotation grinding, as an important processing technology, is widely used in
manufacturing and back thinning of the silicon wafer. However, the surface/subsurface integrity of the ground wafer, which has important influences on the surface quality and the output of the wafer in subsequent process, is becoming an attention-catching problem. This study is aimed at experimental investigation of the surface/subsurface integrity in wafer rotation grinding. The surface roughness, the subsurface crack configurations, the subsurface damage depth (SSD) and the phase transformations are evaluated by corresponding methods. The results show that the integrity of the ground wafer has a close relationship with the grit size of the grinding wheel. The surface roughness and the SSD increase with increasing of the grit size. The subsurface crack configurations of (100) silicon wafers are complicated. The material removal mechanism is different under different grinding conditions. Ductile grinding is accompanied by the phase transformations of diamond structure silicon (Si-I). The amorphous silicon (α-Si), the Si-XII phase (r8-rhombohedral structure) and the Si-III phase (bc8-body-centered cubic structure) exist on the near surface region of the wafer ground by #600 and #2000 grinding wheels.
Study on Ultrasonic Vibration Grinding Character of Nano ZrO2 Ceramics
Authors: Zhao Bo , Zhang X.H. , Liu C.S. , Jiao Feng , Zhu Xun Sheng
Published: March 2009

Nano ceramics possessed ascendant mechanical property and physical characteristics contrast with engineering ceramics, so it has extensive application prospect in various industries. On the basis of applying the indentation fracture mechanics to analyze the removal mechanics of ceramic material, this paper analyzed the critical ductile grinding depth of the nano ZrO2 ceramics. Adopting ultrasonic composite processing we describe the influence of different processing
parameters and grain size of diamond wheel on the grinding forces and surface roughness. Based on the grinding forces and surface roughness the grinding process with and without vibration is analyzed. By means of SEM and AFM the surface character and critical ductile grinding depth of nano ZrO2 ceramics are also discussed. The paper supplied the theoretical and experimental basis for the grinding of the large-sized ultraprecision plate structure of nano ZrO2 ceramics (nm).
Comparative Study on Machining the Internal Stationary Toroidal Gear
Authors: Yao Li Gang , Wei Guo Wu , Lan Z.H. , Dai Jian Sheng
Published: March 2009

The toroidal drive offers the advantages such as a high horsepower-to-weight ratio, coaxial configurations, compactness and high operating efficiencies. It combines most of the positive attributes of a circular worm-gear drive and epicycle gear drive without their negative aspects due to the introduction of a set of rollers in meshing contact with rolling movement between a sun-worm and planet worm-gears, and between a stationary internal toroidal gear and planet worm-gears. However
difficulties were encountered in machining the toroidal surface of the stationary internal toroidal tooth profile. This paper investigates the toroidal meshing surface and develops a mathematical modelling of the meshing surface and the conjugate surface using motion analysis of the epicyclic gear train. Then the enveloping and NC machining methods are proposed and based on these machining methods the stationary internal toroidal gear is manufactured. This results the comparative study of the tooth profile of manufactured toroidal gears by the proposed methods.
Ultra-High Speed Grinding Using a CBN Wheel for a Mirror-Like Surface Finish
Authors: Ota M. , Nakayama T. , Takashima K. , Watanabe H.
Published: March 2009

There are strong demands for a machining process capable of reducing the surface
roughness of sliding parts, such as auto parts and other components, with high efficiency. In this work, we attempted to grind hardened steel to a mirror-like surface finish with high efficiency using an ultra-high speed grinding process. In the present study, we examined the effects of the work speed and the grinding wheel grain size in an effort to optimize the grinding conditions for accomplishing mirror-like surface grinding with high efficiency. The results showed that increasing the work speed, while keeping grinding efficiency constant, was effective in reducing the work affected layer and that the grinding force of a #200 CBN wheel was lower than that of a #80 CBN wheel. Based on these results, a high-efficiency grinding step with optimized grinding conditions was selected that achieved excellent ground surface quality with a mirror-like finish.
Comparison of Two Software Tools for Damage Identification: Gradient-Based vs. Case-Based Approach
Authors: Kołakowski Przemysław , Mujica Luis E. , Vehí Josep
Published: March 2009

Two alternative software tools for damage identification are presented. The first tool, developed on the basis of the Virtual Distortion Method (VDM), takes advantage of an analytical formulation of the damage identification problem. Consequently, gradient-based optimization method is applied to solve the resulting dynamic inverse problem in time domain. Finite element model of the structure is necessary for the VDM approach. The second tool utilizes the Case-Based Reasoning (CBR) for damage identification. This method consists in i) extracting principal features of the response signal by wavelet transform, ii) creating a base of representative damage cases, iii) organizing and training the base by neural networks, and finally iv) retrieving and adapting a new case (possible damage) by similarity criteria. Basic description of both approaches is given. A comparison of numerical effectiveness, in terms of accuracy and computational time, is provided for a simple beam structure. Advantages and weaknesses of each approach are highlighted.
Modal Analysis of Acoustic Emission Signals from Artificial and Fatigue Crack Sources in Aerospace Grade Steel
Authors: Pullin Rhys , Holford Karen M. , Baxter M.G.
Published: March 2009

Current analysis of Acoustic Emission (AE) signals is dominated by waveform parameter assessment, such as amplitude, rise-time, absolute energy, initiation frequency etc. whilst the actual waveform collected is often ignored. This paper explores the dispersive behaviour of Lamb Wave propagation as a means of estimating source to sensor distance and source orientation from collected waveforms.
Model Based SHM - Rotating Machinery Application
Authors: Uhl Tadeusz , Barszcz Tomasz , Bednarz Jarosław
Published: March 2009

The paper presents application of the model based diagnostic method for early detection of faults in rotating machinery. The applicability of modal model identification techniques for structural health monitoring of rotating machinery for linear and nonlinear cases is presented. The method based on both operational and experimental (with specially designed active experiment) is discussed. The approach including mapping of nonlinear system to time varying linear one is employed. The theoretical formulation of the method and experimental verification on laboratory rig is shown.
Experimental and Numerical Investigation of Wave Propagation in Composite Beam with an Additional Mass
Authors: Ostachowicz Wiesław M. , Krawczuk Marek , Palacz Magdalena
Published: March 2009

The article is to show results of numerical and experimental examination of changes in wave propagation in a composite rod with additional mass. For numerical modelling the spectral element method is used. For experimental verification the IFFM PAS laboratory equipment was used. As actuators and sensors PZT elements were utilised. The results obtained via numerical and experimental simulations are compared and discussed.
Simplified Modeling for Impedance-Based Health Monitoring
Authors: Peairs Daniel M. , Park Gyuhae , Inman Daniel J.
Published: March 2009

A new model of impedance-based structural health monitoring (SHM) using the spectral element method (SEM) and electric circuit analysis has been developed. This model provides additional information for more accurately identifying and locating damage and in designing the SHM system. Complex functions of the SHM system such as estimation of remaining life are also made possible with the use of the model. The circuit analysis can be applied to any type of structural model. However, since impedance-based SHM relies on high frequency excitation of the structure using piezoelectric patches, finite element modeling may not be applicable and instead the spectral element method (SEM) is used. SEM more accurately models higher frequency vibrations since the mass is modeled “exactly” and incorporates higher order models more easily. Model and experimental results are presented for damaged and undamaged specimens.
Ultrasonic Damage Measurement in Reinforced Concrete Beams
Authors: Bairrao Rogerio , Chrzanowski Marcin , Duque Joaquim , Latus Pawel
Published: March 2009

In several situations the failure of a reinforced concrete structure is preceded by a
gradual deterioration of the materials which can be recognised by measuring the change of their physical properties [1]. The main purpose of the destructive tests described in the present paper was to obtain an evaluation of the damage evolution in a reinforced concrete beam, submitted to harmonic displacements imposed by means of a shaking table.
A reinforced concrete beam, with two different spans, was designed to sustain a static load of a mass located at the centre of the longer span. Ten identical specimens were prepared and tested at the LNEC (National Laboratory for Civil Engineering, Lisbon) shaking table facility [2]. This paper presents tests, which have been performed in the frame of the European Commission programme ECOEST/PECO (European Consortium of Earthquake Shaking Tables / Central and Eastern European Countries extension). The beams were fixed to the shaking table and submitted to a sinusoidal displacement in the vertical direction, with a pre-established duration and constant amplitude. The tests were carried out by successive stages of increasing amplitudes, until the collapse of each beam was reached. The tests aimed to give an evaluation of the loading history influence on the occurrence of the critical state. During the tests, displacements and accelerations were continuously recorded at several points of the structures, along with ultrasonic measurements taken at different directions, before and after each successive stage.
In the present paper the design of the specimens is given. The instrumentation plan, the test setup and the test procedure are also described. Finally, the most relevant results are shown followed by the formulation of a global damage law to predict the limit state of the beams.
Vibration-Based Seismic Damage Identification in Buildings
Authors: Zapico José L. , González María P.
Published: March 2009

This article deals with a method for seismic damage identification in buildings with steel moment-frame structure. The damage identification is based on artificial neural networks and natural frequencies. A simplified finite element model is used to obtain the data needed for training the nets. The method is simulated on a four-storey building under conditions as close as possible to reality. The robustness of the method and its sensitivity to the variations of the mass with time and the influence of the data errors is addressed. The statistical analysis of the results is successful, but it reveals that the predictions are quite sensitive to the data errors.
Detecting Damage of Rolling Bearings Using EMD
Authors: Gao Qiang , He Zheng Jia , Chen Xue Feng , Qi Ke Yu
Published: March 2009

Empirical mode decomposition (EMD) method is introduced, and a new EMD based approach for damage detection of rolling bearings is presented. In this approach, the characteristic high-frequency signal with amplitude modulation of rolling bearings with local damage is separated from the mechanical vibration signal as an intrinsic mode function (IMF) by using EMD, and an envelope signal can be obtained by using Hilbert transform. Then, the characteristic frequency of damage of rolling bearings is extracted by applying Fourier transform to the envelope signal. The presented approach is used to analyse experimental signals collected from rolling bearings with outer race damage or inner race damage, and the results indicate that the EMD based approach can detect damage of rolling bearings more effectively comparing with traditional envelope analysis method.
Development of an Evanescent Light Measurement System for Si Wafer Microdefect Detection
Authors: Takahashi S. , Nakajima R. , Miyoshi Takashi , Takaya Yasuhiro , Takamasu Kiyoshi
Published: March 2009

In order to reduce and control yield loss in the fabrication process of next generation ULSI devices, nano-defects inspection technique for polished Silicon (Si) wafer surface becomes more essential. This paper discusses a new optical nano-defects detection method, which is applicable to silicon wafer surface inspection for next-generation semiconductors. In our proposed method, the evanescent light is emerged on the wafer surface with total internal reflection (TIR) of infrared (IR) laser at the Si-air interface. By scanning the surface where the evanescent light is emerging with a very shaped fiber probe, it enables to detect nanometer scale defects in the vicinity of Si wafer surface without diffraction limit to resolution. To experimentally verify the feasibility of this method, an evanescent light measurement system was developed and several fundamental experiments were performed. The results show that the proposed Si wafer microdefects detection method can detect the microdefect with 10nm scale on and beneath the surface based on evanescent light distribution.
A High Precision Three-Dimensional Optical Sensor Using Fourier Transform Profilometry
Authors: Sung H.Y. , Tien L.F. , Lin C.Y. , Lo C.Y. , Lin Y.R. , Lin Y.M. , Tao T.H.
Published: March 2009

Automatic measurement of an object shape is very important in solid modeling, machine vision, industrial inspection, and medical diagnostics, etc. We propose an optical sensor, which comprises a telecentric projector with a sinusoidal grating and a linear CCD camera. We use the FTP (Fourier transform profilometry) method to make a measurement on three-dimensional object. In the FTP method, a grating pattern projected onto the object surface is modulated by the height distribution of the object. The deformed fringe pattern is Fourier transformed and processed in the spatial frequency domain as well as in the space signal domain to demodulate the object shape from the main frequency component in the Fourier spectra. This optical sensor provides a rapid and non-invasive three-dimensional image acquisition. The repeatability is better than 5 µm within the 3σ limits.
A Circle Contour Measurement Technique Based on Randomized Hough Transform Using Gradient Information
Authors: Cui Ji Wen , Tan Jiu Bin
Published: March 2009

Hough Transform (HT) is an image edge detection technique which is widely used in pattern recognition and computer vision. In this paper the fundamental principle of HT is analyzed and the defect of HT and Randomized Hough Transform (RHT) is indicated. An algorithm based on RHT and the information of grayscale and gradient in image is proposed. It uses the property of the pattern and is mainly used for detection of circle and arc contour measurement. This algorithm can decrease memory usage in computer by a multi to one mapping, accelerate the calculation speed by parallel algorithm, improve the edge detection accuracy by subpixel division, obtain the parameters of object by applying least square fitting algorithm. Based on the principle, a measurement system with high accuracy and efficiency in image capturing and processing is developed. Experiments are carried out in the system. The result of experiment has certified the feasibility and validity of the algorithm.
Dynamic Measurement of Bearing Radial Clearances
Authors: Chen Yu Xue , Yang S.N.
Published: March 2009

Outer ring tilted or offset axially, caused by improperly fixing relatively to the inner ring, will produce remarkable systematic errors in measured radial clearance of a bearing. Analyzing their effects in detail on the results of measured radial clearances, they are found to be the main sources affecting the measurement accuracy. Measures for removing them are proposed. Based on these, a novel type of instrument for measurement of radial clearances of ball bearings has been developed. It could avoid the two kinds of systematic errors. The measuring principle, structures and working procedures of the instrument are presented. Test results show that the test time is less than 15 seconds per a part and the indication stability is between ±1.0 µm.
Eddy Current Testing Using a Model Based Measurement Method
Authors: Luo F.L. , Hu Yun Yu , Kang Z.W.
Published: March 2009

It is important to improve the reliability of the eddy current non-destructive testing. It is generally difficult to reduce the probability of non-detection and the number of false alarms same time. Model Based Measurement (MBM), including estimation of state, failure diagnosis and trend analysis, has excellent results on general estimation. Actual results of MBM vary with the application domain, mathematical model and data processing. The time series model is a description of system in time domain based on equivalent output. The Kalman filter is an efficient method for suppressing the disturbance and improving the state estimation. A new method, called as eddy current testing (ECT) using a model based measurement, is presented. Two time series models are used for the normal status and the abnormal status in ECT. The Kalman filter on these models is applied to give useful information for decision making. Results of the experiment on aluminum plates demonstrate that this method is useful to improve the detection reliability.