bluuebunny/crossref_metadata_2025 huggingface dataset:
The Analysis Stability of Anchor Retaining Wall
Authors: Benamara Fatima Zohra , Belabed Lazhar
Published: September 2011

The construction of anchored retaining walls reach every day in the field of Civil Engineering especially in public works. Their dimensioning and stability are the axes of research for geotechnical. The rule is to reduce the active forces of the slide and increase the effective normal stress on the rupture surface. So that, we anchored tied-back (constituted by steel cables) in the stable ground located under the failure surface and we apply at the top a traction force. This effort can be distributed over the ground surface by means of small plates or massive reinforced concrete. The study of the stability of anchored retaining wall was also performed by using software GEO4. Many cases can be solved using analytical solutions available in the group GEO4 program, but for our standard model solution studied analytically proved unsatisfactory so we used a numerical analysis based on the method of finite element in this program. The results obtained by numerical study were interpreted to identify the precision numerical predictions. Moreover these methods were useful and economics in the realization of reinforced slopes by tied-buck.
Fly Ash Particle Reinforced AA6061 Composites Produced by Recycling of Aluminum Chips and Fly Ash Particles
Authors: Vatansever Recep , Mindivan Harun , Kayali E.S.
Published: September 2011

In this work, the re-use of aluminum AA6061 chips and fly ash particles by solid-state processes (cryomilling, cold compaction and hot extrusion) is presented. The process was performed in following steps: comminuting of chips, cryomilling of comminuted chips, aluminum powders and fly ash particles, cold pressing-hot extrusion approach without sintering step. Comparative analysis of the recycled composites with fine and coarse granulated chips was focused on mechanical properties and correlated to microstructural features. The density and electrical conductivity of the recycled composites are lower than those of the unreinforced aluminum alloy due to the presence of fly ash particles. Regarding mechanical properties, the recycled composites with coarse granulated chips showed higher hardness and compressive strength than the recycled composites with fine granulated chips, but the compressive strength of the recycled composites with coarse granulated chips decreased with the increase of fly ash content.
Stability of the Walls in Nails Soil
Authors: Benamara Fatima Zohra , Belabed Lazhar
Published: September 2011

Developed as from the seventies, the nailing of the soils is a technique, which makes it possible to carry out a retaining wall of excavation by using the soil in place and installing the passive bars called nails. The main object of this work is to study the stability of the walls in soil nailed lived overall rupture facing-soil-nail. In order to find the mechanism or the mechanical model most unstable. Give a general aspect to our studies; we also studied a title comparative the classical circular failure model. We have repeatedly determined for each case the maximum shear soil force in the nails Tm. The most unfavourable mechanism (less stable) among all the mechanisms is that for which, the shear force Tm reached a maximum. Another analysis of the stability of wall in nailed soil was made by means of the software Geo4 and compared with the kinematics method.
Vibration of Bridges under the Passage of Vehicles Simulated as Moving Loads
Authors: Ouchenane Meriem , Lassoued Rachid , Ouchenane Karima
Published: September 2011

The dynamic behavior of bridges under the effect of moving loads simulating the vehicle moving along the bridge structure idealized by an Euler beam is analyzed. We will present the dynamic behavior of beams under the stress of moving loads (or masses) by the analytical and semi-analytical approaches. When the mass of the bridge structure is comparable to that of the vehicle, the mobile source requesting the bridge is simulated by a mass. In most practical cases, the mobile force used is due to the effects of the gravitational moving masses: . When the moving mass is small compared to the beam mass, the obtained solution under the effect of moving force is approximately correct for the solution obtained with the moving mass. Otherwise, the problem of the moving mass is imperative. To do this, we wrote a program in Matlab language which reflects the dynamic behavior of beams under the effect of moving charges, which gives the following results "The frequencies and modes of vibration, the dynamics deflection of the beam requested by moving force, the dynamic response (DAF: dynamic amplification factor) of the beam requested by a moving force, over the whole length of the beam, for all times and for different speeds. The numerical example that we look to see for study the dynamic behavior of this type of bridge under moving loads is that of a thin beam unamortised on simple support and length of 50m, under the solicitation of moving force and mass at a constant speed and varies from 0 to 100 m / s (M. A. Foda, 1997), depending on the relationship between the vehicle mass and the mass of the bridge that will allow us to see the contribution of the choice of modelling type on the total response and then the vibration of bridge, also we will study the effect of type of simulation of the load by moving force or mass on the dynamic amplification factor and comparing our results with those from the literature.
DC Characterization of Different Advanced MOSFET Architectures
Authors: Jomaah Jalal , Fadlallah Majida , Ghibaudo Gérard
Published: September 2011

A review of recent results concerning the DC characterization of FD- and Double Gate SOI MOSFET’s and FinFETs in modern CMOS technologies is given. By proper extraction techniques, distinction between the different interaction mechanisms is done. Parameter extraction conducted at room and low temperature clearly indicates that the mobility is directly impacted by shrinking the gate length in sub 100nm architectures.
Hydrodynamic Study of Terahertz Three-Dimensional Plasma Resonances in InGaAs Diodes
Authors: Ziadé Pierre , Marinchio Hugues , Palermo Christophe , Kallassy Ziad , Varani Luca
Published: September 2011

We investigate the presence of plasma resonances in InGaAs n+−n−n+ diodes under different optical excitation conditions. In particular, we study the case of diodes submitted to an optical photoexcitation presenting a beating in the terahertz frequency domain. For this purpose, we calculate the electric field response in the middle of the n and n+ regions using a hydrodynamic approach self-consistently coupled to a one-dimensional Poisson solver. In particular, the analysis of the electric field response to an optical beating as a function of the doping and the geometry of the devices allows us to evidence in all the considered cases the presence of resonances in both n and n+ regions. However, while the observed resonances agree with the theoretical 3D plasma frequency in the n+ external regions, we point out a shift towards higher frequencies in the n region. We show that this shift towards the n+ 3D plasma frequency is due to the strong coupling between the two region modes, and tends to disappear when the n region lengthens, whereas the influence of the n+ regions length on the resonance frequency is negligible. Moreover, we show that the amplitude of the plasma resonances can be enhanced at high doping levels and by increasing the level of the optical photoexcitation. The obtained results show clearly that the resonances associated with 3D plasma waves in InGaAs diodes lie in the THz domain for typical values of dopings and lengths, thus opening new possibilities to exploit not only field effect transistors but also diodes as solid-state terahertz devices operating at room temperature.
Design of an Accuracy Current Sensor Using Amorphous Fine Wire of FeCoSiB
Authors: Msaed Aline , Tawk Mansour , Zaatar Youssef , Zaouk Doumit
Published: September 2011

In this paper, we are interested in electric current reconstruction from magnetic field measurements. The major difficulty of this principle is in the ability to reject magnetic field perturbations which affect the accuracy of the measurements. The first experimental validation of the approach of gradient measurement shows large errors in the current reconstruction using two independent fluxgate sensors. These errors were attributed to mechanical alignment and different residual magnetic states of the fluxgate sensors. We then suggested an effective solution able to overcome these problems. This solution consists of a fluxgate gradiometer placed above U-shaped conductor carrying the unknown current to be reconstructed. The experimental results of this system show a good rejection of uniform and non-uniform magnetic field perturbations and furthermore an improvement of the accuracy of the measurements.
Microstrip Bandpass Sensor Based on Distributed Capacitors
Authors: Melhem Zeina , Nader Chadi , Bayard B. , Bechara J. , Rousseau Jean Jacques
Published: September 2011

A microstrip bandpass filter with rectangular patch coupled resonator is presented. The filter is designed to be more affected by the dielectric layer above the conductors compared to the same type of parallel-coupled bandpass filter. The filter is designed to operate between 1 GHz to 3 GHz and this can be a sensor base on distributed capacitors. The agreement between the circuit simulator and measured results is excellent and gives a very good prediction for the filter characteristics. The aim of this prototype filter is to show insertion loss (IL) at the bandpass transmission response when a dielectric material is above or near the conductors. A large study around the sensibility and the effect of the dielectric layer is done in order to evaluate its performance in detection and dielectric characterization.
Hydrogen Production by Methane Steam Reforming Over Ru and Cu Supported on Hydrotalcite Precursors
Authors: Homsi Doris , Aouad Samer , Gennequin Cedric , Aboukaïs Antoine , Abi-Aad Edmond
Published: September 2011

Co6Al2 oxide was prepared using the hydrotalcite route. The obtained solid was thermally stabilized at 500°C and then impregnated with 5 wt.% copper or 1 wt.% ruthenium nitrate solution followed by calcination at 500°C under an air flow. X-ray diffraction results showed that the calcination of the impregnated solids led to the formation of various oxides (CuO, RuO2, Co3O4, CoAl2O4, CoAl2O4). The different impregnated and non impregnated solids were tested in the methane steam reforming reaction (MSR). Methane conversion did not exceed 5% at 800°C in the case of the non impregnated solid, whereas the impregnation strongly enhanced the reactivity: ~89% and ~92% conversions were reached at 600°C for Cu and Ru respectively. The good reactivity of ruthenium impregnated catalyst was attributed to the formation of easily reducible ruthenium and cobalt oxide species at the surface of the support. The addition of ruthenium made the reduction of surface and bulk cobalt oxides possible at lower temperatures.
Progress in Microbial Fuel Cells Energy Production
Authors: Degrenne Nicolas , Buret Francois , Allard Bruno , Monier Jean Michel
Published: September 2011

Microbial fuel cells (MFCs) harness the natural metabolisms of microbes to produce electrical power from almost any kind of organic matter. In addition to the low power densities (about 1mW for a 1-liter reactor), MFCs are presently built with expensive membrane and electrodes. The payback time of MFCs is therefore very long (evaluated to 25000 years for our lab prototype). Progresses in designing low-cost MFCs are necessary before conceiving large scale energy production.
Wide Band Gap Semiconductors Benefits for High Power, High Voltage and High Temperature Applications
Authors: Tournier Dominique , Brosselard Pierre , Raynaud Christophe , Lazar Mihai , Morel Hervé , Planson Dominique
Published: September 2011

Progress in semiconductor technologies have been so consequent these last years that theoretical limits of silicon, speci cally in the eld of high power, high voltage and high temperature have been achieved. At the same time, research on other semiconductors, and es- pecially wide bandgap semiconductors have allowed to fabricate various power devices reliable and performant enough to design high eciency level converters in order to match applications requirements. Among these wide bandgap materials, SiC is the most advanced from a techno- logical point of view: Schottky diodes are already commercially available since 2001, JFET and MOSFET will be versy soon. SiC-based switches Inverter eciency bene ts have been quite established. Considering GaN alternative technology, its driving force was mostly blue led for optical drive or lighting. Although the GaN developments mainly focused for the last decade on optoelectronics and radio frequency, their properties were recently explored to design devices suitable for high power and high eciency applications. As inferred from various studies, due to their superior material properties, diamond and GaN should be even better than SiC, silicon (or SOI) being already closed to its theoretical limits. Even if the diamond maturity is still far away from GaN and SiC, laboratory results are encouraging speci cally for very high voltage devices. Apart from packaging considerations, SiC, GaN and Diamond o ers a great margin of progress. The new power devices o er high voltage and low on-resistance that enable important reduction in energy consumption in nal applications. Applications for wide bandgap materials are the direction of high voltage but also high temperature. As for silicon technology, WBG-ICs are under development to take full bene ts of power and drive integration for high temperature applications.
Metabolic Activation of the Organic Fraction Coated-Onto Air Pollution PM2.5 and its Genotoxicity in a Co-Culture Model of Human Lung Cells
Authors: Abbas Imane , Garçon Guillaume , Billet Sylvain , Verdin Anthony , Escande Fabienne , Saint-Georges Françoise , Mulliez Philipe , Gosset Pierre , Shirali Pirouz
Published: September 2011

Air pollution Particulate Matter (PM2.5) is described as one of the major risk factors affecting human health. Hence, the objective of our research project was to evaluate the lung toxicity of PM2.5 collected in Dunkerque (France), through the study of the metabolic activation of its organic fraction (e.g. Polycyclic Aromatic Hydrocarbons, PAHs; Volatile Organic Compounds, VOCs) and its genotoxicity in two human cell models: embryonic lung epithelial L132 cells and Alveolar Macrophages (AM) isolated from bronchiolo-alveolar lavages of healthy outpatients, in mono- and/or coculture. The coculture system we used allowed the direct exposure of AM to PM2.5, and the interaction between the two cell types only through soluble factor diffusion. Exposure to Dunkerque City’s PM2.5 induced the gene expression of phase I and phase II enzymes (e.g. CYP1A1, CYP2E1, CYP2F1, NQO1, GST∏1, GSTμ3) involved in the metabolic activation of PAHS and/or VOCS, in AM, in mono- and coculture, and in L132 cells, only in monoculture. Taken together, these results reinforced the key role of AM in lung defenses, and indicated that particles, as physical vector of the penetration and retention of coated-PAHS and/or VOCS within cells, enabled them to exert a durable toxicity. DNA bulky adduct formation was also reported not only in Dunkerque City’s PM2.5-exposed AM, in mono- and coculture, but also in L132 cells from PAH-exposed coculture. Loss of Heterozygosity (LOH) and/or MicroSatellite Instability (MSI) of some MicroSatellites (MS) located in multiple critical regions of chromosome 3 were reported in L132 cells from Dunkerque City’s PM2.5-exposed mono- or cocultures.
Inorganic Chemical Composition of Atmospheric Particulate Matter around Industrial Sites in Northern Lebanon
Authors: Kfoury Adib , Yammine P. , Ledoux Frederic , El Khoury B. , El Nakat H. , Nouali H. , Cazier F. , Courcot Dominique , Abi-Aad Edmond , Aboukaïs Antoine
Published: September 2011

Atmospheric Total Suspended Particles (TSP) were sampled from 16 different points in a coastal industrial region in North Lebanon, between April and October 2008. The samples were analyzed for water soluble ions and metals concentrations using Ion Chromatography (I.C.) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The results showed possible natural contribution to aerosols through sea salt emissions (Na/Cl-/Mg), and crustal sources (K/Fe/Ti). However, ions such as NH4+, NO3-, and SO42- were attributed to secondary aerosols. Finally, the result of the enrichment factor analysis showed that vehicles’ emissions (Zn/Cu/Pb/Ni/V/Cr), quarries (Ca), and phosphate rocks impurities (Zn/Cd/Cu/Pb) were the most important anthropogenic contributions to the metal’s load in the aerosols.
Submicrometric Iron Particles for the Removal of Pharmaceuticals from Water: Application to b-Lactam Antibiotics
Authors: Ghauch Antoine , Baydoun Habib , Tuqan Al Muthanna , Ayoub Ghada , Naim Sahar
Published: September 2011

Sub-micrometric iron particles (Fe0) and amended Fe0 (Cu0Fe0) were tested for the aqueous removal of b-lactam antibiotics. Comparative batch experiments were performed separately on aqueous solutions of dicloxacillin (DCX), cloxacillin (CLX) and oxacillin (OXA). Three different initial concentrations (1, 5 and 10 mg L-1) and four different iron loads (r = 10, 20, 40 and 53 g L-1) were tested. Furthermore, two different mixing regimes were tested: (i) non-disturbed conditions, and (ii) vortex mixing. This experimental design enabled the confirmation of the crucial role of in-situ formed iron corrosion products (Fe oxides) on the removal process. The dynamic process of Fe oxides formation induces adsorption and enmeshment (sequestration or co-precipitation) of dissolved antibiotics. Results clearly delineated the superiority of Cu0Fe0 bimetallics compared to Fe0. For example, after 4 h of contact with iron particles at r = 40 g L-1, OXA, CLX and DCX (10 mg L-1 each) disappeared to an extent of 31, 46 and 71%. However, quantitative antibiotic removal (~90%) was noticed when Cu0Fe0 bimetallic was used at lesser load (r = 20 g L-1)under vortex mixing. On the other hand, non-disturbed systems showed partial removal (~ 25%) of antibiotics over 7 h of reaction at r = 10 g L-1 (Fe0) while almost complete removals were noticed for the Cu0Fe0 bimetallic system for the same metal load and period e.g. 75, 79 and 86% removal for OXA, CLX and DCX respectively.
Toxicological Impact of Air Pollution Particulate Matter (PM2.5) Collected under Urban, Industrial or Rural Influence: Occurrence of Oxidative Stress and Inflammatory Reaction in BEAS-2B Human Bronchial Epithelial Cells (Corrected Version)
Authors: Dergham Mona , Billet Sylvain , Verdin Anthony , Courcot Dominique , Cazier Fabrice , Shirali Pirouz , Garçon Guillaume
Published: September 2011

Exposure to air pollution Particulate Matter (PM) is one of the risk factors involved in the high incidence of respiratory and cardio-vascular diseases. In this work, to integrate inter-seasonal and inter-site variations, fine particle (PM2.5) samples have been collected in spring-summer 2008) and autumn 2008-winter 2009, in Dunkerque (France) under urban or industrial influence, and in Rubrouck (France), under rural influence. Attention was paid to characterize their physico-chemical characteristics, and to determine their ability to induce oxidative stress and inflammatory response in a human bronchial epithelial cell model (BEAS-2B cell line). Physico-chemical characterization of the six PM samples showed their heterogeneities and complexities depending upon their respective natural and/or anthropogenic emission sources. Lung cytotoxicity of these air pollution PM2.5 samples, as shown in BEAS-2B cells, might rely on the induction of oxidative stress conditions and particularly on the excessive inflammatory response.
Study of Biomaterials Acoustic Signature Using Annular Lenses
Authors: Bouhedja Samia , Hamdi F.
Published: September 2011

In this work, we study the microstructure of porous alumina Al2O3 through the acoustic signature behavior V(z). This function depends on the low porosity when annular lenses conditions at an operating frequency of 1 GHz are used. In non destructive control, this quantitative investigation which allows the determination of mechanical materials properties is of a great importance in the measurement of the surface waves attenuation in this type of biomaterials. Hence, we have numerically simulated the porous alumina acoustic signatures through variable occultation of generating rays at the lens center, in order to quantify the occultation limiting angle. Consequently, the evaluation of the equivalent Rayleigh velocity using the fast Fourier transform (F.F.T) spectra was achieved thanks to the suppression of the Rayleigh mode generation.
Raman Spectroscopic Study on Decorative Glasses in Thailand
Authors: Won-In Krit , Pongkrapan Sorapong , Dararutana Pisutti
Published: September 2011

Glasses have been used as decorative objects in Thailand for several hundred years. Decorative glasses can generally be seen as architectural components in old styled palaces and Buddhist objects. There were various colors ranging from transparent to amber, blue, green and red with different shades among glass of different colors. Fragments of archaeological glass samples were characterized for the first time using Raman microscopy with the aim of obtaining information that would lead to identification of the glass samples by means of laser scattering. The samples were also investigated using other techniques, such as particle induced X-ray emission spectroscopy and scanning electron microscope operated with energy dispersive X-ray fluorescence spectrometer. They were mostly lead-silica based glasses. The colors resulted from metal ions. The difference in chemical composition was confirmed by Raman signature spectra.
IAEA Activities on Cultural Heritage, Archaeology and other Characterization Applications
Authors: Mulhauser Francoise , Salame Petra , Simon Aliz , Zeman Andrej , Kaiser Ralf , Haji-Saied Mohammad
Published: September 2011

Trace element determination is crucial for identifying the provenance and authenticity of intact ancient objects such as cultural and art artefacts, archaeological findings and forensic materials, geological objects, etc. A non-destructive technique suitable for analysis of trace elements in bulk-samples is highly needed. The IAEA initiated a series of coordinated research projects (CRP) to support Member States on their R&D programs. Large Sample Neutron Activation Analysis (LSNAA) is a very attractive non-destructive technique that can be applied without a need for sub-sampling and homogenization. LSNAA can be operated in ‘on-line’ mode which is based on the use of isotopic neutron sources, neutron generators and prompt gamma analysis. An on-going CRP focuses primarily on the application of LSNAA in the area of archaeological and geological programmes. However, further utilization of LSNAA in other subjects of industry and research is promising. Large scale campaigns of archaeological excavations are undertaken in the Mediterranean region. The IAEA is supporting Technical Cooperation projects in the Middle East in view of studying authenticity and origin of objects of art and archaeology, as well as to characterize new elaborated materials or environmental samples, making use of Ion Beam Accelerators (IBA) as nuclear analytical tool and other nuclear analytical techniques. The application of nuclear analytical tools in archaeology is of special concern as many common ancient civilizations are shared by the Mediterranean state. The main IBA techniques to be used are: PIXE, PIGE and RBS, as well as XRF. To take advantage of these nuclear techniques, many researchers from the participating countries have initiated several studies and exchange of experience, knowledge, results and expertise is on-going.
Effect of Powder Characteristics on the Densification of Sintered Alumina
Authors: Al Sarraj Ziyad S. A. , Noor S.S.
Published: September 2011

Abstract. The effect of particle size distribution, soaking time and sintering temperatures on the densification behaviors of α-Al2O3 was investigated. Two different average particle sizes of 36 and 45µ were examined as a variable to analyze the difference in density, radial and axial shrinkage, densification, and microstructure developments. Conventional powder technology route was used to prepare disc-shaped green pellets sintered at 1200-1600°C for different periods. Density measurements for both green and sintered compacts allow for the refinement of processing parameters to obtain dense sintered bodies. Compacts with particle size of 36 µm were noticed to attain higher relative densities as compared with those of 45µm. Densification parameter (∆P) calculations clearly reveals the presence of definite temperatures and times in which limited densification retardation occurred, which permits the suggesting of suitable sintering schemes for this material. Scanning electron micrographs analysis revealed a pore structure assist the observed behaviours for the different schemes.
Pulsed Laser Deposition of Tungsten Thin Films on Graphite
Authors: Kassem Wassim , Tabbal Malek , Roumie Mohamad
Published: September 2011

Thin coatings of Tungsten were deposited on substrates fabricated by pre-depositing graphite thin layers on Si(100) wafers. We ablate pure W target using a 20 ns KrF excimer laser (248 nm) in an Ar ambient. The effect of background gas pressure, substrate temperature, and laser fluence, on the properties of the deposited W layers is studied using several techniques including X-Ray Diffraction, Atomic Force Microscopy, surface profilometry, and Rutherford Back-Scattering spectrometry. Our results indicate that the deposited layers consist of the well-crystallized body-centered-cubic α-W phase with bulk-like properties, particularly for films deposited at a substrate temperature of 450°C, laser fluence greater than 400mJ, and pressure of about 10mTorr.
Design of Functional Polymer and Composite Scaffolds for the Regeneration of Bone, Menisci, Osteochondral and Peripheral Nervous Tissues
Authors: Guarino Vincenzo , Gloria Antonio , Alvarez-Perez Marco A. , Raucci Maria Grazia , Cirillo Valentina , Ronca Alfredo , de Santis Roberto , Ambrosio Luigi
Published: September 2011

In order to mimic the behaviors of natural tissue, the optimal approach for designing novel biomaterials has to be inspired to nature guidelines. One of the major challenge consists in the development of well-organized structures or scaffolds with controlled porosity in terms of pore size, pore shape and interconnection degree able to guide new tissue formation during the in vivo degradation following the scaffold implantation. Scaffolds endowed with molecular cues together to a controlled degradation profile should contribute to cell proliferation and differentiation, controlled vascularization, promoting the remodeling of neo tissue through a gradual transmission of bio-chemicals and biophysical signals as performed by the extracellular matrix (ECM). Here, different polymers and composites have been investigated to design scaffolds with peculiar micro and/or nanometric morphological features in order to satisfy all these requirements: a) bioactive scaffolds, with tailored porosity and high pores interconnectivity were developed by integrating PLA fibres, Calcium Phosphates particles or Hyaff11 phases into a Poly(ε-caprolactone) (PCL) matrix by the combination of filament winding technology and phase inversion/salt leaching technique as mineralised ECM analogue for bone regeneration; b) custom made PCL/hydroxyapatite scaffolds were designed by imaging and rapid prototyping technologies for the osteochondral defect. c) Ester of Hyaluronic Acid reinforced with degradable fibres were processed by composite technology, phase inversion and salt leaching technique, to obtain scaffolds for meniscus regeneration. d) PCL and gelatin nanofibres were obtained by highly customized fibre deposition via electrospinning to guide the nerve outgrowth in nerve regeneration. All the proposed approaches offer the chance of realizing tailor-made platforms with micro/nanoscale architecture and chemical composition suitable for the regeneration of the extracellular matrix of a large variety of natural tissues (i.e, bone, menisci, osteochondral and peripheral nervous tissues).
Streamer-Surface Interaction in Heptane with Micro-Gaps
Authors: Hamdan Ahmad , Noel Cedric , Hénrion Gérard , Belmonte Thierry
Published: September 2011

Interaction between streamer and 316L Stainless Steel substrate in heptane with micro-gaps gives craters with a very specific shape. The role of the Marangoni forces is stressed, a phenomenon which is generally neglected in EDM processes to describe the shape of the craters.
Quantification the Effect of the Thickness of Thin Films on their Elastic Parameters
Authors: Gacem Amel , Doghmane A. , Hadjoub Z.
Published: September 2011

The determination of the characteristics and properties of thin films deposited on substrates is necessary in any device application in various fields. Adequate mechanical properties are highly required for the majority of surface waves and semiconductor devices. In this context, modelling the ultrasonic-material interaction, we present results of simulation curves of acoustic signatures for multiple thin film/substrate combinations. The results obtained on several structures (Al, SiO2, ZnO, Cu, AlN, SiC and Cr)/(Al2O3, Si, Cu or Quartz) showed a velocity dispersion of the Rayleigh wave as a function of layer thickness. The development of a theoretical calculation model based on the acoustic behaviour of these structures has enabled us to quantify the dispersive evolution (positive and negative) density. Thus, we have established a universal relationship describing the density-thickness variation. In addition, networks of dispersion curves, representing the evolution of elasticity modulus (Young and shear), were determined. These charts can be used to extract the influence of thickness of layers on the variation of elastic constants
Influence of Magnetron Effect on Barium Hexaferrite Thin Layers
Authors: Hassane Harouna , Chatelon Jean Pierre , Rousseau Jean Jacques , Siblini Ali , Kriga Adoum
Published: September 2011

In this paper, we study the effects of a magnet, located in the cathode, on barium hexaferrite thin films deposited by RF magnetron sputtering technique. During the process, these effects can modify thickness, roughness and stress of coatings. The characteristics of the deposited layers depend on the substrate position that is located opposite of magnetron cathode. In the "magnetron area", one can observe that the high stress can produce cracks or detachment of layers and the increasing of both depositing rate and surface roughness. After sputtering elaboration, barium hexaferrite films are in a compressive stress mode. But, after the post-deposition heat treatment these films are in a tensile stress mode. To improve the quality of BaM films, the subsrtate has to be set outside the magnetron area.
Grinding of Steel-Ceramic-Composites
Authors: Denkena Berend , Köhler Jens , Hahmann Dennis
Published: September 2011

Steel-ceramic-composites offer a high potential as protective layers of mechanically and abrasively high loaded machine parts. The machining of steel-ceramic-composites is a high challenge for the process design due to the very different material properties of the brittle ceramic particles, embedded in the ductile steel matrix. Both materials have to be machined in ductile mode simultaneously to gain high surface qualities. Thus, the material separation mechanisms have to be understood for an adequate process design. In this paper, a new process characteristic is introduced that describes the influence of the grinding process settings on the process forces and workpiece surface roughness in grinding steel-ceramic-composites.
FEM Analysis of Single Grit Chip Formation in Creep-Feed Grinding of Inconel 718 Superalloy
Authors: Zahedi Ali , Akbari J.
Published: September 2011

Recent advances in materials science have necessitated the development and understanding of manufacturing processes for safe and repeatable utilization. Grinding is shown to be a promising material removal process especially for brittle and hard to cut materials such as superalloys. Grinding has always been associated with analysis and modeling complications regarding its nature which has limited its extension and reliability of use. The first step in analysis of grinding is considering the action of a single abrasive grit on workpiece surface. In this work the action of a single CBN abrasive grit in creep-feed grinding process of Inconel 718 superalloy is modeled and analyzed using a 3D FEM software, DEFORM. Thermal and mechanical characteristics of the mutual interaction between grit and workpiece surface, and different chip formation phases are defined which can further be used to analyze the whole process.
Analysis of Specific Energy of TC18 and TA19 Titanium Alloys in Surface Grinding
Authors: Niu Qiu Lin , Guo Guo Giang , Cai Xiao Jiang , Liu Zhi Qiang , Chen Ming
Published: September 2011

As two kinds of advanced titanium alloys, TC18 and TA19 were introduced in this paper. The machinabilities of TC18 and TA19 alloys were described in the grinding process. Grinding experiments were completed using green silicon carbide grinding wheel with the coarser 100 grit. Grinding forces and specific energy in surface grinding were investigated. And then, for studying the grinding characteristic, SEM images of the workpiece material were obtained. The results indicated that specific chip formation had the great effect on the mechanism of grinding TC18 and TA19 alloys, and the scratch was the main characteristic of surface grinding. TC18 alloy had the poor grinding performance compared to TA19 alloy.
Dressing Process of Porous Self-Generation Superabrasive Tool
Authors: Lv Bing Hai , Wu Zhe , Yuan Ju Long , Fan Hong Wei
Published: September 2011

The dressing principle of a newly developed metal bonded superabrasive tool named porous self-generation superabrasive tool (PSST) is introduced. It is found that the ‘soluble’ filler added in the bond material can be dissolved by certain solution, and porous structure can be formed on the highly compacted surface layer of the metal-bonded superabrasive tool. The dressing process of PSST are investigated by a series of lapping experiments. Surface topography of PSST during lapping process is observed. It is found that the porous structure can be maintained on the PSST surface layer during the lapping process. There is little jam happened on the PSST surface. The generated porous binder on PSST surface layer is more susceptible to bond fracture, which is benefit to the self-sharpening of the metal bonded superabrasive tool.
Influence of Picosecond Laser Touch Dressing of Electroplated Diamond Wheels on the Dressing of SiC Vitrified Bond Wheel
Authors: Rabiey Mohammad , Dold C. , Transchel R. , Wegener K.
Published: September 2011

Touch dressing of electroplated diamond wheels is a challenging technique used for precision form grinding. This paper presents an investigation to explore the capabilities of modern laser technology for touch dressing. A pulsed picosecond laser (ps-laser) beam (Yb:YAG) is used to cut diamond grains within a definite grain protrusion without noticeable thermal damage neither on the nickel bond material nor the diamond itself. A systematic study on laser irradiation parameters on cutting quality is presented. Series of experiments by dressing of SiC wheels using an ultrashort pulsed laser source as well as conventional touch dressed diamond wheel are carried out and both methods are compared. Significant advantages of the novel laser method are presented.
Analysis of EDD Accuracy for Profiling Metal-Bonded Grinding Wheels
Authors: Ortega N. , Pombo Inigo , Sánchez Jose Antonio , Plaza Soraya , Izquierdo B.
Published: September 2011

Grinding process using superabrasive metal-bonded wheels is unavoidably linked to long and inefficient truing and dressing processes. This document presents the application of electro-discharge dressing process as an alternative to form wheels. The accuracy of the process and its efficiency has been analyzed on wheels of different grit size. To do so, complex geometry has been completely profiled to a 1A1 type wheels. Results show that the process can provide the desired geometry at the cost of a high processing time. The comparison between fine and large grit size grinding wheels shows that there is apparently no geometric limitation imposed by the grit size apart from that associated to grit diameter in corners and inner radii.
Experimental Study on Performance of Monolayer Brazed Diamond Wheel through Chemical-Mechanical Dressing
Authors: Su Hong Hua , Xu Jiu Hua , Fu Yu Can , Ding Wen Feng , Wang Shuai
Published: September 2011

The dressing methods of monolayer diamond tool have recently been developed increasingly because a substantial improvement of the ground surface roughness could be achieved with the dressed monolayer diamond tools. In this paper, a new dressing method was proposed, namely chemical-mechanical dressing of the diamond grits. Dressing experiments were carried out on the monolayer brazed diamond grinding wheel. The grit-tip distances from the base of wheel substrate were measured before and after dressing. Grinding experiments were conducted on K9 optical glass after each dressing interval. The roughness parameters of the ground surfaces were measured. The outcome of this attempt appeared highly encouraging, and the dressing of monolayer brazed diamond grinding wheel is effective with the chemical-mechanical dressing.
Improvement of Grinding Performance of a CBN Wheel Using a New Grinding-Fluid-Supply System
Authors: Kitajima Takayuki , Okuyama Shigeki , Yui Akinori
Published: September 2011

This paper proposes a new grinding-fluid-supply system for improving the grinding performance of a CBN wheel. The system generates cavitations in the fluid flow, which is expected to provide higher cooling and superior grinding-chip removal capability. The system is applied to one-pass surface grinding of steel plates, and residual stress and surface roughness are evaluated. The system has a major effect on improving surface roughness, but has a minor effect on reducing the residual stress under shallow-cut grinding conditions. The effects appear greater under the heavier grinding conditions.
3-D CFD Parametric Study of the Impact of the Fluid Properties and Delivery Conditions on Flow and Heat Transfer in Grinding
Authors: Mihić Stefan , Cioc Sorin , Marinescu Ioan , Weismiller Michael C.
Published: September 2011

Fluids have an important role in grinding. Correct fluid application results in enhanced process stability, better work piece quality, and tool life. This paper shows that Computational Fluid Dynamics (CFD) models can be used to simulate the fluid flow and heat transfer in a grinding process, replacing numerous experiments that are expensive, time-consuming, and have limited capabilities. The most important properties of created 3-D model are described, along with results obtained. The results show very detailed distributions of temperatures, pressures, and flow rates in and around the grinding region. The data obtained is essential in studying the influence of the grinding fluid on the grinding process, as well as in determining the best fluid composition and supply parameters for a given application. The results agree well with experimental global flow rates and temperature values and show the feasibility of 3-D CFD-based simulations in grinding applications. The parametric studies of influence of several fluid physical properties on useful flow rates and temperatures were presented as well.
The Mechanics and Mechanisms of Material Removal in Abrasive Drilling C/E Composites
Authors: Wen Q. , Gao Hang , Guo Dong Ming , Wang B.
Published: September 2011

The abrasive drilling achieves high hole qualities in processing carbon/epoxy (C/E) composites. In order to investigate the cutting force and the material removal mechanism for drilling C/E composites with abrasive drilling tool, this paper presented a mechanistic model to predict the cutting force of single grain. The model assumes fibers as a beam with two ends fixed. The beam is subjected to extrusion of diamond grain and mainly fractures by tensile damage. The failure mode is then validated by finite element simulation and scratching experiment. The cutting simulation of single grain using Abaqus showed fracture occurred in the points with maximum tensile stress. The tensile damage results in many claval chips. Local fiber tensile damage is the mainly failure mechanism for the fibers, accompanying the fiber compressive failure and shear failure.
Process Parameters Influence on Semi-Fixed Abrasive Tool Wear
Authors: Deng Qian Fa , Zhao Ping , Lv Bing Hai , Yuan Ju Long , Wang Zhi Wei
Published: September 2011

Abrasive machining is an important process for the manufacturing of advanced ceramics. The demand for advanced ceramics with better quality and higher efficiency presents tremendous challenges for abrasive tools in the advanced ceramics industry. The concept of semi-fixed abrasive machining with a newly developed semi-fixed abrasive tool (SFAT) as machining tool is put forward. This paper presents an experimental investigation for SFAT wear into course of machining single crystal silicon with SFAT. Process parameters (water flow, load and velocity) influencing the SFAT wear are analyzed. Influencing factor of SFAT wear in processing course has been clearly demonstrated.
Effect of Complex Electrodischarge Grinding for Electrically Conductive PCD
Authors: Iwai Manabu , Ninomiya Shinichi , Suzuki Kiyoshi
Published: September 2011

Polycrystalline Composite Diamond (PCD) is excellent in chipping resistance despite its very high hardness. However, it is not easy to EDM or grind PCD. To realize high efficiency and high quality processing of PCD simply and at low cost, the authors devised new PCD (EC-PCD) by using electrically conductive diamond particles and applied a complex electrodischarge grinding method. In this study, investigation is made on effective grinding condition to realize high efficiency, low and stable grinding force and low wheel wear in complex electrodischarge grinding. As a result, superior grinding property was obtained when the grinding wheel was set at minus polarity, and set peak current of iP = 4 and 6 A was applied. Furthermore it also became clear that additional conventional grinding process followed after complex electrodischarge grinding improved the surface condition.
Development of Three-Dimensional Measurement System of a Grinding Wheel Surface with Image Processing
Authors: Sakaguchi Akihiro , Kawashita Tomoyuki , Matsuo Shuji
Published: September 2011

Grinding process is a very efficient machining technology because innumerable abrasive grains are fixed on the surface of grinding wheel. Especially, the distribution and shape of cutting edges which directly affect grinding process have a big influence on accuracy. Thus, it is very important to measure a wheel surface topography from a viewpoint of evaluating the wheel life and the performance and a relation between the one and the roughness. In this study, a three-dimensional measurement system of a grinding wheel surface with image processing is developed. In this system, the distribution and height of cutting edges are analyzed because only cutting edges can be selected from among all abrasive grains.
Evaluation of Vibration Finished Surfaces Using Image Processing Method
Authors: Higuchi Shizuichi , Takai Hiroaki , Kato Hideo , Okawa Kazuya
Published: September 2011

Vibration finishing which is often applied to the metal surfaces recently is the finishing method using a disk-type finishing tool with movements of rotational and orbital motion [1]. However, an application of this finishing method and an evaluation of finished surfaces require skills and sensory examinations. This is because the relations between finishing conditions and quality of finished surfaces are not clear. In recent years, image processing methods for evaluating finished surface roughness and texture analysis were proposed [2 - 5]. However, quantitative evaluation has not been fully done.
Study on Processing Property of Thin-Walled Titanium Alloy Component with Paraffin Reinforcement
Authors: Ge Mao Jie , Sun Jie , Li Jian Feng
Published: September 2011

This paper reveals the deformation and vibration properties of thin-walled component with and without paraffin. Deformation characteristics of the thin-walled titanium alloy component acting with transient cutting force were investigated by static analysis. Based on the milling experiments with and without paraffin, acceleration signals, deformation and surface roughness were measured and analyzed. The results show that paraffin reinforcement can significantly enhance the machining stability, improve the surface finish and reduce the distortion of workpiece.
Atmosphere Effects on the Machinability of Cutting Tools with Micro- and Nanoscale Textures
Authors: Kawasegi Noritaka , Sugimori Hiroshi , Morita Noboru , Xue Min Chao
Published: September 2011

Cutting and friction experiments were conducted in various atmospheres to investigate the chemical effect on textured cutting tools. The cutting experiments indicated that the atmosphere affected the machinability of the textured tools; a larger effect was observed in the presence of gas such as oxygen. A ball-on-disk friction apparatus was developed and used for the friction experiments. Smaller friction coefficients were observed in the presence of oxygen, a trend similar to that observed during the cutting experiments. These results indicate that oxidation is an important factor in determining the texture effect for machining aluminum alloy.
Defect Structures in Diamond Composite Coated Cemented Tungsten CarbideSubstrates
Authors: Boland Jim N. , Li Xing S. , Hay D. , MacRae Colin M. , Elbracht S. , Rassool Roger P. , Luzin Vladimir , Imperia Paolo
Published: September 2011

Variability in the abrasive wear of PCD coatings on cemented WC substrates has been investigated. Six samples of PCD coated carbides were tested in a wear testing rig. The PCD coated element was used to turn an industry standard vitrified bonded corundum grinding wheel. The wear rate was measured as the weight loss of the cutting element per cubic metre of grinding wheel machined during the test. Two grades of cutting elements were observed. One grade had wear rates between 6 and 7.3 g/m³ but of the three poor quality samples, only one valid test was made realising wear rate of ~7,800 g/m³. The microstructures of the samples were studied using SEM, X-ray imaging, neutron diffraction and XRD. SEM images revealed differences in the volume percentage of diamonds in the two grades and the XRD scans highlighted the variable distribution of the diamond phase in the coating. Estimates of the residual stresses in a good and poor quality samples indicated significantly higher compressive stresses in the good quality versus poor quality coating. These results have revealed two extremes in the wear rates of these PCD coated carbides. It is suggested that the difference in diamond content between the two grades is not sufficient to account for the 3 orders-of-magnitude difference in the observed wear rates. However, the presence of intrusive veins of carbide material in the coatings, especially around the curved cutting tip, suggested that the macroscopic defects observed in the x-ray and SEM images were the major cause of the high wear rates in the poor quality sample.