bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Unascertained Measure-Entropy Evaluation Model for Program Selection of Shaft Construction under Complex Conditions
Authors: Li Wan Qing , Chen Mu Jie , Meng Wen Qing
Published: April 2011

An unascertained measure-entropy evaluation model for the program selection of shaft construction under complex conditions is established so that a scientific and effective decision making method is provided in this paper, the evaluation model of shaft construction is established based on unascertained measure and entropy weight theory, then, the model proposed in this paper is applied to evaluate three shaft construction program comprehensively, and the evaluation results show validity and applicability of the model.
Incremental Mining Algorithm of Sequential Patterns Based on Frequent Sequence Tree
Authors: Liu Jia Xin , Yan Shu Ting , Ren Jia Dong
Published: April 2011

At present, the existed incremental mining algorithms can not make full use of the results of the previous mining. When the support is changed, the algorithms need to mine the database once again. In this paper, we propose an incremental mining algorithm of sequential patterns based on frequent sequence tree, called IMFST. When the database is updated and the support is changed, IMFST is divided into four kinds of situations to update the frequent sequence tree, and finally gets all sequential patterns. IMFST uses two kinds of pruning strategies to reduece the size of the projected databases. When the support is changed and the support is no less than the frequent sequence tree support threshold, IMFST can find all the sequential patterns without mining the database once again. Experiments show that IMFST outperforms PrefixSpan and IncSpan in time cost.
Finite-Time H∞ Control of one Family of Fuzzy Discrete-Time System with Norm-Bounded Disturbance
Authors: Liu Cai Xia , Zhang Ying Qi
Published: April 2011

This paper deals with finite-time control problem of a class of fuzzy discrete-time system with time-varying norm-bounded disturbance. Applying the Lyapunov function theory and matrix inequalities, a sufficient condition is obtained for robust finite-time stability and the fuzzy system satisfies a prescribed level for the effect of the disturbance input on the controlled output.
Applications of the Soave-Redlich-Kwong Equations of State Using Matlab
Authors: Sun Lan Yi , Zhai Cheng , Zhang Hui
Published: April 2011

In this paper, using Matlab to solve Soave-Redlich-Kwong (SRK) EOS, as well as the estimation of pure component properties, plotting of vapor-liquid equilibrium (VLE) diagram and calculation of chemical equilibrium, is presented. First the SRK EOS is used to predict several pure-component properties, such as liquid and gas molar volumes for isobutane. The vapor-liquid isobaric diagram is then plotted for a binary mixture composed of n-pentane and n-hexane under the pressures of 1.5*10^5 and 7*10^5 Pa respectively. Finally, the extent of ammonia synthesis reaction under high pressure is calculated.
Research and Practice of Integrated Microgrid System Control
Authors: Che Yan Bo , Chen Jian , Zhao Bo
Published: April 2011

Microgrid system, as the carrier of control strategy, can provide verification platform for the research. This paper discusses the control strategy firstly. And then an integrated microgrid system with multi-microgrid structure, containing a variety of distributed generations, energy storage systems, diesel generator and adjustable loads, is introduced. The control strategy of the microgrid system which adopts master-slave control strategy is discussed in detail. The result shows that the mircogrid system using control strategy proposed in this paper can transfer flexibly between grid-connected and islanded mode. This system is able to work well with operation control and other related technologies.
Emotion Fusion Recognition for Intelligent Surveillance with PSO-CSVM
Authors: Wang Rui Hu , Fang Bin
Published: April 2011

The next generation of intelligent surveillance system should be able to recognize human’s spontaneous emotion state automatically. Compared to speaker recognition, sensor signals analyzing, fingerprint or iris recognition, etc, facial expression and body gesture processing are two mainly non-intrusive vision modalities, which provides potential action information for video surveillance. In our work, we care one kind of facial expression, i.e. anxiety and gesture motion only. Firstly facial expression and body gesture feature are extracted. Particle Swarm Optimization algorithm is used to select feature subset and parameters optimization. The selected features are trained or tested for cascaded Support Vector Machine to obtain a high-accuracy classifier.
Analysis of TIG Arc Spatial Radiation Based on Scanning Method
Authors: Liu Fu Qiang , Li Zhi Yong , Gu Xiao Yan
Published: April 2011

The article collected radiation intensity of TIG arc plasma in different dimensions and analyzed arc spectrum by establishing horizontal scanning system of plasma. Choose Fe and Ar characteristic spectral line as the subjects; acquire the distribution of arc radiation in different dimensions through Abel conversion; calculate temperature of plasma using Boltzmann. The results indicated that the position of strongest radiation is about 1mm from the tungsten pole, then it gradually weakens along the radial direction and the gradient of Ar spectral line is greater. The lowest temperature is near the base metal and the highest one is near tungsten pole.
An Empirical Study on Extended Producer Responsibility in Auto-Manufacturing Industry
Authors: Wu Yi , Hu Xiao Han , Nie Jing
Published: April 2011

Extended producer responsibility has become an important managerial system to dematerialize our economy. This paper aims to verify the five promotional factors of extended producer responsibility, and to investigate its applicability in the auto-manufacturing industry. A questionnaire survey has been conducted in the auto-maufacturing industry, followed by principle component analysis and description analysis of the data collected. As a result, five promotional factors have been verified and auto-manufacturing industry is proved a promising industry in terms of EPR implementation. Future strategies are put forward based on the promotional factors.
Research on Movement and Deformation of Rock Strata between Coal Seams in Pillar Upward Mining of Left-Over Coal with Numerical Simulation Method
Authors: Feng Guo Rui , Zheng Jing , Liu Hong Fu , Zhong Cong Ming
Published: April 2011

Based on the occurrence condition of coal seams and the geological condition on coal seam mining in Coal Mine Group Baijiazhuang, after pillar mining the 8th coal seam was well controlled, ascending mining the 6th coal seam, mining process was numerically simulated by FLAC3D,the variation law of displacements field on interlayer strata between the 6th coal seam and the 8th coal seam at different face advance were analyzed. Vertical displacement on rock strata increased gradually from below. A control stratum existed on rock strata and could play a control function for steady of strata movement, which provides a theory basis for further study on upward mining.
Comparative Study on SaaS Data Layer Solution
Authors: Liu Ya Juan , Wen Hao Yu , Zha Jun
Published: April 2011

According to the Characteristics of the business model for SaaS, appropriate data layer solution need to be selected to the system development. Through an analysis of independent database, independent data structure and shared databases shared framework, and combining with actual application scope and scene, the selection strategy of SaaS data layer solution is given.
Laser Beam Measurement Based on Image Enhancement Algorithm
Authors: Li Yu Hong , Ding Wei , Ding Shan
Published: April 2011

This paper puts forwards a novel algorithm for laser beam measurement based on the enhancement of infrared image, which has strong noise background and low contrast. First, laser beam image were divided by “three order invariant moments” with the idea of statistical probability, and objects that need to be measured were extracted; Then, four mathematical models were established on the basis of “γ-correcting” algorithm, and an improved“(a, b, γ)-correction” algorithm which is based on PSO algorithm has been proposed by solving the mathematical models respectively. The PSO algorithm will be used in the process of the enhancement of laser beam.
Wind Erosion Prevention and Repair of Composite Material Components of Civil Aircraft
Authors: Yu Hao Qing , Gong You Gen , Liu Ai Ping
Published: April 2011

This paper addresses how to discover wind erosion of aircraft components in time and to take appropriate measures to repair and prevent damage, thereby reducing the cost of aircraft maintenance and prolonging aircraft service life. The authors of this paper have extensively compiled and studied civilian aircraft maintenance data in the recent years from Guangzhou Aircraft Maintenance Engineering Co. Ltd. In this paper they discuss the aircraft components most susceptible to wind erosion, as well as repair methods and prevention mechanisms. These findings can serve as a reference and a guide to civilian aircraft flight maintenance, repair, and routine inspections.
Microscopic Mechanism Analysis and Experimental Study of Void Beneath Slab
Authors: He Hai Ying
Published: April 2011

The main cause of cement concrete pavement fracture is void beneath slab, while water is an important factor of void beneath slab. In order to clearly understand impact of water on void beneath cement concrete pavement, this paper analyzes penetration soaking role and scouring of water and studies the evolution process of void under slab. It is founded that the erosion of the grassroots and void beneath the plate influence each other. Conducting a Small-size simulation test by using Falling Weight Deflectometer (FWD), the movement condition of the water in empty area under concrete road and the effect of void size on current scour are got under the action of moving load.
Investigation on Knowledge Work Process and its Characteristics Based on Human-Information System (H-IS) Interaction
Authors: Liao Yi , Yi Shu Ping , Li Fa Quan
Published: April 2011

This paper investigates knowledge work process and its characteristics based on human-information system (H-IS) interaction using concurrent protocol and observation methods. It is found that the ability of knowledge workers to obtain information feedback from information system (IS) is a key factor affecting the information processing speed of knowledge work. Therefore, an enhanced H-IS collaboration reduces the total time of knowledge work and improves knowledge work efficiency. In addition, when IS is applied to semi-structured knowledge work, H-IS interaction has insignificant influence on the quality of the task.
Research on Semantic Web Services Composite Model Based on the OWL-S
Authors: Wu Tie Zhou , Xiang Jian Feng , Wang Ming Yue
Published: April 2011

Because the traditional Web service lacks of the description of the semantic level. Construction semantic Web service has become the development trend of traditional Web service and based on the semantic web, the service composition technology is also evolved with demand. On the basis of analyzing the traditional Web service composition technology, the paper researches the related critical technology of constructing semantic Web service，and then uses the method by combining the ontology modeling with the OWL-S to improve the traditional service composition model. Finally, the practicality and convenience of the improved model have been proved by the experiment.
Comparative Studies of CdZnS Thin Films at Low Zinc Content Prepared by Vacuum Evaporation and CBD
Authors: Tian Cai Juan , Tang Rong Zhe , Hu Song Bai , Li Wei , Feng Liang Huan , Zhang Jing Quan , Wu Li Li
Published: April 2011

Cd1−xZnxS thin films at low Zn content were prepared both by chemical bath deposition (CBD) and vacuum co-evaporation. The X-ray fluorescence (XRF) and X-ray photoelectron spectroscopy (XPS) analysis were performed to determine the composition of the films, while the structural properties were investigated by X-ray diffraction (XRD). As a probable window layer, the optical band gaps of Cd1−xZnxS thin films prepared by the dry and wet process were calculated. Finally, the surface morphologies of the thin films were survey by scanning electron microscopy (SEM) and atomic force microscopy (AFM).
The Applications of the Flood Forecast System Based on OGSA-DAI
Authors: Shi Ya Qing , He Yin Jun
Published: April 2011

Combined with the grid services technique, this paper analyzed the realization of flood forecasting system model based on OGSA-DAI and provided the distributed calculation platform for the flood forecasting deployment on Internet.
Characteristics and Treatment Technologies of Stainless Steel Slag
Authors: Ma Guo Jun , Fang Yi , Tang Hui
Published: April 2011

The stainless steel slag contains chromium and iron as well as significant levels of heavy metals, such as Cr(VI). Therefore, to efficiently recovery the valuable components in the stainless steel slag has potential environment and economic profit. In this paper, the physical and chemical properties as well as the leaching properties of the stainless steel slag were summarized. In addition, the treatment processes which can recovery or utilize the valuables in the slag and other potential measures to reduce the environmental pollution of the stainless steel slag were also discussed.
Optimization of Extractive Condition of Zanthoxylum Alatum Seed Oil
Authors: Zhang Lei , Chang Min , Su Ming , Niu Sheng Yang
Published: April 2011

This article focuses on the topics of excraction of Zanthoxylum alatum seed oil, which have the positive significance to maintain the human health. The author used Zanthoxylum alatum seeds as the raw material, by macerate extraction method, found that the levels of extractive temperatures, extractive strengths and extractive time are significant to the extractive effect. Through the results of orthogonal experiment, the author’s conclusion is that the best combination of extraction for Zanthoxylum alatum seed oil is: the extractive strength is 99.5%, the extractive temperature is 80°C and the extractive time is 2h.
A Deformation Method for Soft Objects Based on Surface Area-Preservation
Authors: Chen Hong Qian , Cao Jian , Chen Yi
Published: April 2011

To simulate the deformation for soft objects, proposes a local deforming method based on surface area-preservation. The cylinder mesh is employed as the basis mesh to bypass its build step and to uniform the deformation algorithm. The damping curve is employed to simulate the gofferes appearing in the inside section of surface. The gofferes can improve greatly the deformation results. Surface area-preservation and detail-preservation are achieved to improve the authenticity of deformation. The method has been proved feasible and valid to simulate the bending deformation for soft object by experiments results.
Determination Method of Critical Path in Fuzzy Network Planning Based on Improved Lattice Close-Degree Theory
Authors: Li Wan Qing , Chen Mu Jie , Meng Wen Qing , Ma Li Hua
Published: April 2011

For the determination of the critical path in fuzzy network planning, the traditional methods can not identify the differences of fuzzy distribution between different fuzzy sets, in this paper, an improved method of lattice close-degree is proposed which two proportion factors are introduced in the fuzzy support and kernel sets, then, the differences are recognized well and an effective way to determine the critical path in fuzzy network planning is provided. Further more, the correctness and feasibility of the method proposed in this paper are proved by example analysis, the calculation results show that the critical path could be well determined in fuzzy network planning.
Optimization Algorithms for Local Features
Authors: Cao Jian , Chen Hong Qian , Mao Ming Yi
Published: April 2011

Feature spaces optimization plays a very important role in object recognition and categorization. After analyzing of several fashionable local features at present, some optimization algorithms based on the information theory are proposed. In this paper, we describe the approaches to recognize generic objects using these features which have been optimized. As baselines for comparison, we also implemented some additional recognition systems using other optimization algorithms. The performance analysis on the obtained experimental results demonstrates that the proposed optimization algorithms are effective and efficient.
Online Video Teaching System Research Based on P2P Technology
Authors: Xu Lin , Zhang Qin , Zhang Jian
Published: April 2011

P2P technology has become one of the most effective approaches to internet video broadcast for its simple deployment, good scalability and high cost-effectiveness ratio. This article proposed technology based P2P-based online video teaching system,P2P technology will be compared with traditional technologies, described the demand characteristics of online video, online video systems network architecture and design method, discussed the media data distribution algorithm from the node management, buffer management, data-driven,Video source coding.Finally get research conclusions.
Research of Chinese Segmentation Based on MMSeg and Double Array TRIE
Authors: Xu Lin , Zhang Qin , Wang Dan Dong , Zhang Jian
Published: April 2011

Chinese segmentation system is a difficulty in computer Chinese information handling. A deep discussion on methods of MMSeg and double array TRIE Chinese segmentation matching on the basis of existing technology in Chinese segmentation is made. On this basis of it , some im2provements are made in the dictionary construction and segmentation arithmetic , designing a Chinese segmentation system based on MMSeg and double array TRIE. Experiment shows that the improving arithmetic accelerated the speed of Chinese segmentation.
A New Type of ECG Signal Sample and Analysis System
Authors: Liu Xuan Chao , Feng Xiao Li , Li Pei Pei
Published: April 2011

With the change of the human life style, heart disease has become one of the main diseases threatening human life and health. Promptly, accurately and completely achieving electrocardiogram (ECG) signal has vital significance for discovering and treating heart disease as soon as possible. However, the traditional professional electrocardiograph has complex structure, high price, and it is not suitable to carry on the popularization application. Therefore, this article proposes a new type of ECG signal sample and analysis system based on a personal computer, which realizes acquisition and analysis function through the LabVIEW programming. The research result shows that it has not only perfect function, convenient operation, easy to use, but also low price, and it is very suitable to universal application. So, it has very good practical value.
Slicing Contour Generation of Z-Constant Contour Machining for Subdivision Surface
Authors: Yuan En Tao , Shao Bing , Fei Qui Xian
Published: April 2011

For the Z-constant contour machining, a slicing contour generation procedure for subdivision surface is presented. Subdivision surface defines a smooth surface as the limit of a sequence of successive refinements starting from an initial control mesh. It can easily generate smooth surfaces of complex arbitrary topology without intricate patch stitching and curve trimming. Instead of randomly intersecting each facet with a slicing plane and having to construct the slicing contour later, this paper takes full use of the topological information of subdivision surface to construct the slicing contour. The contour information is collected as marching from one effective edge to neighboring effective edge. Example shows our method is obviously easier and the complexity has been reduced
Computer Simulations of Laser Ablation, Plume Expansion and Plasma Formation
Authors: Bogaerts Annemie , Aghaei Maryam , Autrique David , Lindner Helmut , Chen Zhao Yang , Wendelen Wouter
Published: April 2011

An overview is given of different modeling work that has been carried out, and is currently going on in our research group, in the field of modeling for laser ablation (LA). Most emphasis will be put on nanosecond (ns) LA, more specifically describing the laser-solid interaction, leading to heating, melting and vaporization of the target, by a heat conduction model, the expansion of the evaporated plume in vacuum or in a background gas by a set of conservation equations, and the plasma formation in the plume, assuming local thermal equilibrium. Some first results for nanoparticle formation in the expanding plume will be presented as well. Also, the process of target heating in the case of femtosecond (fs) LA will be described by means of a two-temperature model, and phase transitions, more specifically evaporation, will be illustrated by means of molecular dynamics simulations.
Electromagnetic Modeling of Microwave Axial Injection Torch at Atmospheric Pressure Used for Thin Film Deposition
Authors: Ikhlef Nabil , Mekidèche Mohamed , Leroy Oliver , Tibouche Ammar
Published: April 2011

This article describes the three dimensional electromagnetic modeling of a microwave (2.45 GHz) plasma device, based on an axial injection torch (AIT). The model solves Maxwell's equations by the finite integration technique (FIT). We are interested in obtaining the optimal position of the short circuit in order to obtain the best percentage of coupling at 2.45 GHz. and understanding the influence of various geometrical parameters on the physical distribution of the electromagnetic field and on the power transfer within the structure.
Light Scattering Techniques Applied to Materials Science
Authors: Comins J.Darrell
Published: April 2011

Light scattering techniques provide powerful methods to investigate a variety of different materials properties. Brillouin scattering is used to the study the elastic properties of bulk solids and thin supported films at ambient and high temperatures. Work on iron pyrite and tungsten carbide films are described as illustrations with theoretical methods using surface Green’s functions being used in the analysis. Raman scattering is used to study corrosion and passivation of iron in an alkaline solution and stress patterns in diamond plastically deformed at high temperature.
Modelling Sequential Impact of Molten Droplets on a Solid Surface in Plasma Spray Process
Authors: Kriba Ilhem R. , Djebaili A.
Published: April 2011

Plasma spray deposition is one of the most important technologies available for producing the high-performance surfaces required by modern industry. In this process, powder of the coating material is fed into high-temperature plasma, which melts and accelerates the powder; the molten particles subsequently hit and solidify on the surface to be coated. To obtain good quality coating, the powder particle must be at least partially molten and hit the substrate with a high velocity. The flattening characteristics of the droplets impinging on a substrate are important determinants in governing the eventual quality of the plasma spray coating. Different codes have been developed in recent years to simulate the overall thermal spraying process, as well as the growth of the 3D coatings, in which entrained particles are modeled by stochastic particle models, fully coupled to the plasma flow. The present investigation was carried out to have an approach to systematize the atmospheric plasma spraying process in order to create a basis for numerically modeling the plasma dynamics, the coating formation mechanisms and to predict the particle thermo- kinetic state at impact.
Fluid Model Simulation of DC Glow Discharges
Authors: Bahouh Hanene , Rebiaï Saida , Bouanaka Fouzi , Sahli Salah
Published: April 2011

The purpose of the present work consists in the elaboration of numerical computing program allowing the simulation of various species behaviour present in plasma reactor during films formation by cold plasma in DC glow discharge. After application of some simplifying hypotheses, we have developed a simulation model based on a fluid approximation. The elaborated model was based on finite differences method solved by MATLAB software. We applied the model to simulate the plasma in the case of atomic gases (Ar) and molecular (CH4) gases. The simulation results are given in terms of spatial distribution of charge densities, electric potential and electric field between electrodes space. The effect of some discharge parameters such as the pressure, and the density of the gas was also investigated.
PIC-MC Simulation Method of DC Discharge Plasmas
Authors: Bouanaka Fouzi , Rebiaï Saida , Bahouh Hanene , Sahli Salah
Published: April 2011

We propose in this paper a numerical particle type model PIC-MC (Particle-In-Cell Monte Carlo) for modeling plasma reactors in the case of DC discharge used for various industrial applications. The model is developed in the case of argon plasma at low pressure, generated in a reactor consisting of two flat electrodes parallel and spaced 3 cm. The collisions treatment is based on the “null collision” method. PIC-MC model can provide the plasma characteristics (potential, field and charge density) in inter-electrodes space, for all reactions in addition to collisions that may occur.
Optimization of the Plasma Display Panel Characteristics with PIC-MCC Method
Authors: Benstâli Wafà , Belasri Ahmed
Published: April 2011

In this paper, we present Plasma Display Panel (PDP) cell discharge using a 1D Particle in Cell with Monte Carlo Collisions model. The effect of gas pressure on the PDP characteristics including current density, voltage margins and energy balance is then studied in order to show the optimized conditions to obtain more energy dissipated in xenon excitation. The results show, at first, the spatiotemporal variation of the electric field and charges densities. It is also seen that for more important gas pressure, there is an increase of the current density, voltage margins and the energy deposited into xenon excitation and ionization.
OES Diagnostics of HMDSO/O2/CF4 Microwave Plasma for SiOCxFy Films Deposition
Authors: Chabane Rayene , Sahli Salah , Zenasni Azziz , Raynaud Patrice , Segui Yvan
Published: April 2011

SiOF like films have been elaborated in microwave excited DECR plasma reactor (Distributed Electron Cyclotron Resonance) from a mixture of oxygen-hexamethyldisiloxane (HMDSO/O2) and CF4. The fluorine contents in the precursor mixture were adjusted by varying the CF4 gas flow ratio in the range of 10% - 70%. Optical emission spectroscopy (OES) and Fourier transform infrared (FTIR) have been used for the plasma diagnostic and the deposited films structure analysis, respectively. Actinometric technique was used to find trends in the concentrations of species present in the plasma. A large number of species have been detected, such as F, Si, O, C and H. Depending on the gas mixture composition, FTIR spectra revealed the presence of several chemical bonds such as Si-F and Si-O.
Effect of the Plasma Deposition Parameters on the Properties of Ti/TiC Multilayers for Hard Coatings Applications
Authors: Saoula Nadia , Henda Karim , Kesri Rafika
Published: April 2011

Titanium carbide (TiC) hard coatings have been obtained on steel and silicon substrates by r.f. magnetron sputtering process. Two layer coatings have been deposited in order to improve adhesion on steel. The lower layer was titanium metal and the upper TiC layer was obtained by reactive sputtering of the titanium target in Ar and methane gas mixture. The study confirmed that the TiC layer composition depends on the reactive sputtering gas composition. Film microhardness was measured by microindentation. Measurement results showed that high hardness coatings can be prepared at a relative low concentration of methane in gas mixture and that good adhesion on steel is achieved with the two layer coating.
Computation of the Net Emission Coefficient with the Overlapping Lines Consideration on the CH4-Ar Plasma Discharge
Authors: Benallal Rafik , Liani B.
Published: April 2011

Net emission coefficients of radiation were calculated for isothermal plasma of CH4 –Ar as a function of the plasma temperature 5,000–30,000 K and the arc radius (0–1 cm) at various plasma pressures. Calculations take into account continuum and line radiations. The line shapes in our calculations are given by convolution of Doppler and Lorentz profiles, resulting in a simplified Voigt profile. The overlapping lines have also been taken into account. In the case of hydrogen profile, we used the Vidal tables, and the four first Lyman lines and the four first Balmer lines have been considered in this work. Values of net emission coefficients calculated for various spectral regions were compared with others author’s works.
Modeling of a Ne-Xe-HCl DC Discharge for Excimer Lamp
Authors: Bendella Soumia , Belasri Ahmed
Published: April 2011

A mathematical model was developed to describe a DC discharge of a Ne-Xe-HCl for excilamp. To achieve our aims we used a one-dimensional model of the cathode sheath coupled to a zero dimensional model of plasma with the external circuit. The spatial profiles of the electron density, ion density and the electric field were shown to exhibit distinct structures of glow discharge. A current in DC discharge increase in monotonous way until reaching 52 A at 225 ns. The breakdown delay times have been calculated, the plasma breakdown is occurring at 160.75ns. The orders of the values of the electric field (105 V/cm) are a condition of the good operation of the excimer lamp. This model permits us to have a good resolution of the sheath region, and to provide a quantitative analysis of the time evolution of the electrical and chemical discharge properties.
Study of the Adhesion and the Thermal Stability of CrN and CrAlN Thin Films
Authors: Mammeri Fatima Zohra , Chekour Lounis , Rouag Nadjet
Published: April 2011

The chromium nitride thin layers have became more and more popular in the last decade because of their good physical, chemical and mechanical properties. The present study deals the morphological characterization of hard Cr-N and CrAlN thin layers deposited on silicon (100) substrates by physical vapour deposition (PVD). The effect of the annealing temperature on the adherence and the thermal stability of CrN layers are considered. SEM observations and EDS microanalyses were performed. Cr-N films, 1μm thick, were annealed for 1 hour at 600 to 1000°C under flux of nitrogen. These layers presented a good thermal stability at low temperatures. Moreover SEM observations showed that the CrN films had a low adhesion at high temperatures. In addition, after annealing at 700°C for 4 hours, CrAlN coating of 1μm thickness presents a better thermal stability than CrN coating but with lower adherence. The results given by SEM-EDS and XRD are compared.
Numerical Study of Butt Joining by Coaxial Powder Injection
Authors: Amara El Hachemi , Tamsaout Toufik , Kheloufi Karim , Berger Herman , Pityana Sisa
Published: April 2011

A 3-D transient modelling based on the numerical resolution of the fluid flow ant the heat transfer equations is developed for butt welding using the cladding process. The physical mechanisms included in our model concern the matter melting, and the re-solidification. The implementation of developed procedures called User Defined Functions (UDFs) working interactively with Fluent CFD code, and a dynamic mesh method, allows to treat the problem with its specific and complex boundary conditions. The fusion, resolidification, and the temperature dependence of the physical properties are taken into account. As results, clad formation and information on the temperature field are obtained.
Dry Sliding Wear of Stainless Steel Coating Obtained by Plasma on Aluminium Substrate
Authors: Khanafi-Benghalem Nafissa , Benghalem Kamel , Loucif Kamel , Aounnallah Soufyane , Redjechta Abdelouahab
Published: April 2011

It is sometimes imperative to modify the characteristics of materials surface reserved for the applications requiring the particular tribological properties in order to confer them certain specific properties such as the improvement of hardness, the corrosion resistance and the wear resistance. The use of aluminium and its alloys in mechanics is limited for their certain properties related to the surface whose principal one is very bad frictions behaviour, associated with a tendency of seizing and a strong sensitivity to the effect of wear. The deposit plasma is a technique which can cure these bad behaviours. It is particularly adapted to treat superficially parts of complex geometry and of rather significant number. Our work consists to study the wear behaviour of stainless steel coatings obtained by plasma on aluminium alloy substrates. The wear tests were carried out using a pin-on-disc apparatus under dry sliding conditions. Pin specimens were 100Cr6 stainless steel, while disc specimens were 316L stainless steel coating. A study will be undertaken on the tribological behaviour of the layers and the mechanisms of wear which control them for various experimental conditions (speeds and normal force) is defined, at four sliding speeds (44, 56.5,75.4, 94.3 m/s) and force of 20N.
Electrical Characterization of Inductively Coupled Plasma Reactor Excited by RF (13.56MHz)
Authors: Alim Mohamed Mounis , Zekara Mourad , Henni Laid , Tadjine Rabah , Henda Karim
Published: April 2011

In the surface treatment by plasma, the saturation ion current is the macroscopic parameter which can give us information on the ionic density in plasma. For this, we followed the evolution of the saturation ion current versus the pressure and power. Our experimental setup consists of spherical plasma reactor linked with inductively source argon plasma and probe to measure ionic current. The obtained experimental results enabled us to highlight the effect of pressure and power on saturation ion current. We found in this study that the saturation ion current increases with pressure and presents an optimum depending on the power.
Optical Properties of a-C:H Films Deposited by Plasma Microwave Discharge with Controlling Substrate Temperature
Authors: Kihel M. , Sahli Salah , Clergereaux R. , Raynaud P. , Segui Y.
Published: April 2011

Amorphous hydrogenated carbon (a-C:H) films have been deposited in Microwave Multipolar plasma reactor (MMP) using pure acetylene as precursor with controlling substrate temperature. Investigations on the optical properties of deposited films according to the substrate temperature have been reported. It has been observed that the optical band gap decreases and the Csp2 concentration increases when cooling down the substrate temperature. On the other hand, it has been revealed elsewhere that cooling down the substrate temperature during the deposition process, leads to the increase of particles trapped density in the deposited films due to a phenomenon of thermophoresis. Therefore, the optical properties evolution is linked to the increases of particles trapped density in the deposited films.
Development of a Radiofrequency Plasma Diagnostic System with a Langmuir Probe and Study of a Capacitively Coupled Argon Plasma
Authors: Mendil Djelloul , Lahmar Hadj , Ouadjaout Djamel , Henni Laid , Boufendi Laïfa , Louhibi Djelloul , Henda Karim
Published: April 2011

A single rf-compensated cylindrical Langmuir probe has been developed in order to characterise a plasma RF discharge. A circuit using radiofrequency filtering and the passive compensation method was employed to minimize the probe curve distortions. The effect of the rfcompensation on the probe measurements was discussed. The latter were performed at power and pressure of 50 W and 510-2–1.2 mbar, respectively. Compensated measurements of the electron energy distribution function (EEDF) and plasma parameters were conducted at powers ranging from 5 to 120 W and pressure of 0.3 mbar. They exhibit a transition between the stochastic electron heating mode operating at low powers and the secondary-electron emission heating mode (γ) operating at high powers. The electronic density increases from 1.5×109 to 3.2×1010 cm-3 while the effective electron temperature decreases from 3.7 to 2.3 eV. The EEDFs were found to be Druyvesteyn-like in the range of 5–80W and then evolve to the Maxwellian beyond 90W.
Numerical Simulation of Laser Bending of Thin Plate Stress Analysis and Prediction
Authors: Tamsaout Toufik , Amara El Hachemi
Published: April 2011

Laser forming is a technique consisting in the design and the construction of complex metallic work pieces with special shapes difficult to achieve with the conventional techniques. By using lasers, the main advantage of the process is that it is contactless and does not require any external force. It offers also more flexibility for a lower price. This kind of processing interests the industries that use the stamping or other costly ways for prototypes such as in the aero-spatial, automotive, naval and microelectronics industries. The analytical modeling of laser forming process is often complex or impossible to achieve, since the dimensions and the mechanical properties change with the time and in the space. Therefore, the numerical approach is more suitable for laser forming modeling. Our numerical study is divided into two models, the first one is a purely thermal treatment which allows the determination of the temperature field produced by a laser pass, and the second one consists in the thermo-mechanical coupling treatment. The temperature field resulting from the first stage is used to calculate the stress field, the deformations and the bending angle of the plate.
Investigation on Thin Films Deposited by PECVD from a DiPhenylMethylSilane (DPMS) Vapors or Mixed with Oxygen for Low-K Material Application
Authors: Bouledjnib Leila , Sahli Salah , Zenasni Azziz , Raynaud Patrice , Segui Yvan
Published: April 2011

A new class of low-k materials thin films, deposited from a DiPhenyleMethylSilane (DPMS) vapors was prepared using PECVD technique. These films are elaborated in microwave excited DECR plasma reactor (Distributed Electron Cyclotron Resonance) from pure DiPhenylMethylSilane (DPMS) using various plasma discharge power (100-400 W) or mixed with 50% of oxygen (O2).The improvements of film properties were investigated by capacitance–frequency (C–f), current–voltage (I–V) techniques and Fourier transform infrared spectroscopy (FTIR). The obtained results show that an increase in plasma discharges power from 100 to 400 watts leads to the decrease in dielectric constant value from 4.4 to 3.7 (measured at 10 kHz). The incorporation of oxygen improves the dielectric properties of the films; the dielectric constant value was reduced to 2.9.
Enhancement of Blue Spectral Response Intensity of PbS via Polyethylene Oxide-Adding for the Application to White LEDs
Authors: Kaci Samira , Keffous Aissa , Trari Mohamed , Mahmoudi Brahim , Menari Hamid
Published: April 2011

In this work, we have employed chemical bath deposition (CBD) method to obtain nanocrystalline PbS thin films in the presence of polyethylene oxide (PEO). The spectral response of Au/PbS-pSi(100)/Al Schottky photodiodes at different PEO amount were studied. The response exhibits a combined effect of photogeneration in the heterojunction (HJ) Si side and PbS. Spectral response were observed progressively at shorter wavelength due to the surface absorption. The peak centered at 410 nm properly corresponds to photo-exited holes being injected from PbS to the Si substrate. The intensity of the peak of R(λ) increases with PEO amount, this increasing was attributed to the decreasing of band gap (Eg).
Study of Optical and Structure Properties for Different Composition Tin-Antimony-Selenium Thin Film
Authors: Abdel-Rahim Farid M.
Published: April 2011

Amorphous Se100-x (Sn Sb)x glasses with (0 ≤ x ≤ 20 at. %) were prepared by the usual melt quench technique. Thin films for these compositions were prepared by thermal evaporation onto ultrasonically cleaned glass substrates kept at room temperature. From the spectral dependence of the absorption coefficient, a direct electronic transition was mainly responsible for the photon absorption inside these films. The effects of composition on the optical properties of Se100-x(Sn Sb) x thin films was investigated. The refractive index, n, for the as-prepared and annealed films has been analyzed according to the Wwmple–DiDominico single oscillator model. The effect of addition (Sn Sb) on the nature and degree of crystallization has been investigated by studying the structure using transmission electron microscope, X-ray diffraction and scanning electron microscope.
Laser Ablation in Liquids: Colloidal Nanoparticles Synthesis
Authors: Messaoud Aberkane Sabrina , Boudjemai Said , Kerdja Tahar
Published: April 2011

The formation of Ti and Si nanoparticles by laser ablation of metallic targets in liquid environment is reported. The use of Second Harmonic Generation (SHG) pulsed Nd-YAG laser (532 nm, 15ns, 20 Hz repetition rate) allows a good rate of nanoparticles (NPs) formation. The NPs were characterized by UV-Visible transmission spectrometry and (SEM) scanning electron microscopy. The results show spherical Ti NPs and squared Si NPs. The optical band gap energies of the colloidal solutions were estimated for the two targets as function of the laser fluences.
A Review of the Laser Pyrolysis Technique Used to Synthesize Vanadium and Tungsten Oxide Thin Films
Authors: Shikwambana Lerato , Govender Malcolm , Mwakikunga Bonex , Sideras-Haddad Elias , Forbes Andrew
Published: April 2011

Laser pyrolysis is one of the most important and emerging techniques used to synthesize thin films, nano-powders and nano-structured materials. The advantages in this technique include: a well defined interaction volume, no interactions with the reactor chamber walls hence less impurities, and the attainment of very fine particles. In this paper we briefly review the development and the current status of laser pyrolysis world wide. However, the main focus is an overview of our efforts to synthesize vanadium and tungsten oxides using this technique since 2006. We discuss the role of the laser pyrolysis parameters: the beam waist, interaction volume, carrier gas flow rates, laser wavelength and power density on the phase, size and shape of the final products obtained.
In Situ Metal Matrix Composite Surfacing by Laser Surface Alloying
Authors: Majumdar Jyotsna Dutta
Published: April 2011

Laser as a source of focused energy may be applied for the modification of microstructure and/or composition of the near surface region of a component. The technique may be applied for the development of a ceramic/intermetallics/interstitial compound dispersed metal matrix composite layer on the surface of metallic substrate by melting the substrate with a high power laser and simultaneous addition of alloy powders for the development of metal matrix composite layer by in-situ reactions. In the present contribution, development of metal-dispersed and intermetallic-dispersed matrix composite layer on the surface of metallic matrix has been discussed with a suitable example of its application.
Laser-Based Additive Manufacturing of Metals
Authors: Kumar Sanjay , Pityana Sisa
Published: April 2011

For making metallic products through Additive Manufacturing (AM) processes, laser-based systems play very significant roles. Laser-based processes such as Selective Laser Melting (SLM) and Laser Engineered Net Shaping (LENS) are dominating processes while Laminated Object Manufacturing (LOM) has also been used. The paper will highlight key issues without going into details and try to present comparative pictures of the aforementioned processes. The issues included are machine, materials, applications, comparison, various possibilities and future works.
Detection and Reinforce of a Reinforced Concrete Box Culvert Suffered a Conflagration
Authors: Jiang Tian Hua , Peng Jing Rong , Zhang Wei Ming
Published: April 2011

When a reinforced concrete structure suffers from a big fire, its quality will change and its bearing ability will be reduced. It is necessary to take a comprehensive testing and to formulate corresponding reinforcement to restore the structure. This article mainly talks about a series of detections and their results of a reinforced concrete culvert which suffered from fire, and then selects a better reinforcement program. It can provide reference for the reinforcement of similar concrete structures.
Dealing with End Effect of EMD Based on Gray Theory
Authors: Han Zhen Nan , Gao Jian Xin , Li Yue Xian , Sun Wen Ting
Published: April 2011

EMD is an effective analysis method of non-stationary signal, but the end effect exists in the process of decomposition. As for the end effect problem, GM(1,1) of gray theory model is used to predict and modify the extension values at endpoints in this paper, which makes the cubic spline interpolation envelope more effective in the course of sifting. The result shows that this method is reasonable by using it to analyze gear fault signal.
Preparation of Metal Cobalt Powder by Co-Precipitation and Heat Decomposition Method
Authors: Xue Ping , Guo Xue Yi , Tian Qing Hua
Published: April 2011

A novel chemical precipitation method was studied to prepare the metal cobalt powder from the precursor Co(OH)x(CO3)y powder. From XRD and IR analysis, it was proved that there were interactions between the NH4+, Cl- and the precursor powder of Co(OH)x(CO3)y. Based on DSC-TGA analysis, the influence of additive and temperature on the cobalt powder preparation process was observed during heat decomposition. The results showed that pure metal cobalt was obtained when the amount of the additive tartaric acid was about 60% and calcination temperature was 500°C.
Study on Group Behavior of Short Crack for Low Cycle at High Temperature Based on Fractal Theory
Authors: Wang Zheng , Wang Kui , Wang Lu , Zhao Zi Hao
Published: April 2011

The propagation of fatigue short crack is a fractal curve, the irregular path can be described by fractal dimension. The fractal dimension of the crack implicit in many of the physical factors, such as microstructure of material, load conditions and so on. In this paper, the short crack for low cycle at high temperature is studied. The material 20# steel in the various stress state is experimentally studied, the initiation, propagation and coalescence influence of short crack are observed. By analyzing experiment results, characters of crack fractal dimensions evolving with the cycle process are as follows, the behavior of short fatigue cracks satisfies fractal feature, with the development of the fatigue process, the fractal dimension is increased.
Characterization of Surface Composition and Microstructure of H21 Steel Implanted Using Masking Ti-Implantation
Authors: Yang Jian Hua , Li Song
Published: April 2011

Ti ions were implanted into H21 steel to improve the surface structure of oxides in H21 steel. The wear characteristics of the implanted steel was measured and compared to the performance of the un-implanted steel by a line-cutting apparatus and an optical interference microscope. The Ti concentration depth profile of the implanted steel was measured by Rutherford backscattering spectroscopy (RBS). The structure and composition of oxides were analyzed by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), respectively. The results showed that the improved wear resistance of the implanted steel was mainly due to the structure and composition changes of the surface oxides after Ti ion implantation.