bluuebunny/crossref_metadata_2025 huggingface dataset:
Grid Task Scheduling Strategy Based on Particle Swarm Optimizationand Ant Colony Optimization Algorithm
Authors: Wei Peng Cheng , Shi Xi
Published: May 2010

Based on particle swarm optimization algorithm, this paper presents a grid scheduling optimization algorithm combing the advantages of Ant Colony optimization algorithm. The algorithm processes task scheduling through particle swarm optimization algorithm to get a group of relatively optimal solutions, and then conducts small-area local search with Ant Colony optimization algorithm. Theoretical analysis and results of the simulation experiments show that this scheduling algorithm effectively achieves load balancing of resources with comprehensive advantages in time efficiency and solution accuracy compared to the traditional Ant Colony optimization algorithm and particle swarm optimizationalgorithm, and can be applied to task scheduling in grid computing.
Enhanced 2&4 Tx Matrix a Scheme Based on Coordinate Interleaved Orthogonal Designs
Authors: Lu Xin , Lu Yun Ting , Zhan Shao Bin
Published: May 2010

Space-time block codes(STBCs) based on coordinate interleaved orthogonal designs (CIOD) are put forward integrally by analyzing the theory of generalized orthogonal designs. In accordance with the principle of Alamouti’s orthogonal receiver, the received signals are firstly processed by vector orthogonal transform, imaginary part exchange and vector-weighted spin processing, then we get the complete demodulation process. Finally, simulations for the transmit diversity configuration A with 4Tx CIOD in 802.16d/e were performed over quasi-static Rayleigh flat-fading channel. The results show that the proposed transmission scheme has a low decoding complexity similar to the classical STBC based on complex orthogonal designs(COD). However, the former can get slightly better performance.
The Study on Artificial Intelligence for Fault Diagnosis in Power Transformer
Authors: Xue Qing Ji
Published: May 2010

A power transformer is an important fault reason for a power system, some uncertain factors such as randomness and funniness exist between fault phenomenon and fault mechanism. There are no definite corresponding relations between fault characteristic quantity and fault omens, which make fault diagnosis more difficult. The transformer fault of artificial neutral network diagnosis is more and more paid attention to, but when the normal artificial neutral network calculations to the data are trained, most of them have slow convergent speed, even no convergent. The paper proposed to improve artificial neutral network calculation, thus increase training speed and diagnostic reliability. It states that artificial intelligence system is very useful tool for transformer early hidden faults achieves the possibilities and accuracy of primary diagnosis.
Arithmetic Research of Computer Simulation of the Bus Junction Stations
Authors: Luo Yong , Guo Xiu Chun
Published: May 2010

This paper will construct a discrete system's computer model, include the time distribution of buses arrive, stop and passengers’ get down and get off. The emulation clock advanced with the method of incident step length. Through the inversion produce the random variables of Poisson distribution, negative exponential distribution and normal distribution, simulate the conditions of bus arrive, leave and pick up passengers. Finally calculate with the relative data and then get a series of indicators to evaluate the crowing degree of the bus station.
Road Traffic Accident Management Information System Research Based on C/S Structure
Authors: Luo Yong , Guo Xiu Chun
Published: May 2010

In this paper we mainly discuss the traffic accident information management system which based on web software platform of WINDOWS NT using PB as front developing tool and adopting the database of SYBASE as its core. The system can make statistical analysis and prediction for road accident caused by many factors and can determine the Black Spot of accident through analysis thus can provide basis for preventing the accident and rebuilding the dangerous road section.
Frame Coding Complexity Prediction in H.264/AVC Rate Control
Authors: Tian Ling , Zhou Yi Min , Sun Yu , Sun Shi Xin
Published: May 2010

H.264/AVC video coding standard inherited the quadratic rate-distortion model of VM8, and proposed a linear tracking model to predict Mean Absolute Difference of the current frame. Since Rate-Distortion Optimization is introduced, the frame coding complexity MAD is predicted in H.264/AVC rate control. However, any single-mode prediction approach of frame coding complexity has its shortages due to unexpected changes of video source. In this paper, we induct the frame coding complexity based on extensive experiments, and propose an optimized choice approach to predict the frame coding complexity. Simulation results demonstrate that the novel approach for frame coding complexity gains better precision than that of joint model in H.264/AVC reference software.
A Hybrid KPCA-PNN Approach to Condenser Fault Diagnosis with a Particle Swarm Optimizer
Authors: Wang Xiao Xia
Published: May 2010

Diagnosis of condenser abnormality is very important for turbine generator reliability. This paper presents a novel approach for condenser fault diagnosis based on kernel principle component analysis (KPCA) and probabilistic neural network (PNN). KPCA is applied to PNN for feature extraction. It firstly maps data from the original input space into high dimensional feature space via nonlinear kernel function and then extract optimal feature vector as the inputs of PNN to solve condenser fault classification problems. A global optimizer, particle swarm optimizer (PSO), is employed to optimize the parameters of PNN to improve fault classification accuracy. The experimental results show that the proposed approach has a better ability in terms of diagnosis accuracy and computational efficiency compared with a number of popular fault diagnosis techniques.
Chinese Calligraphy Brush Stroke Interactive Model with Ink Diffusion Style
Authors: Chen Tian Ding
Published: May 2010

This paper presents an interactive method of using ink diffusion, and gradually approaching simulation brush character with style of Chinese painting and calligraphy. Try to use materials based on the Chinese ink painting: ink and rice paper, according to their characteristics to build the diffusion rules to simulate text ink. Although the initial can show the phenomenon of ink rendering, they can only show diffusion of the ink with black lines, Can not rendering a complete ink diffusion behavior, it is difficult to form a sense of artistic calligraphy. It proposes Interactive model to amend the power of the brush pen and puts forward a binding behavior of ink broken down. The results show that based on the pratice physical meaning, considering the interaction of the two materials(ink and rice paper), appropriate to improve the mathematical equation model to render the calligraphy image more in line with Chinese ink painting style.
Ion Beam Bio-Engineering and Crop Breeding
Authors: Wang Tie Gu , Li Xue Bin , Yang Tian You , Wang Wei Dong
Published: May 2010

Ion beam bio-engineering was established by Chinese researcher in 1980s. Over thirty years past, there were delightful progress by low energy ion beam induced mutants and crop improvement. When ion beam implant the organism, charge exchanged between ions and organism surfaces. Meanwhile there were ion sputtering, ion penetration and surface damage of plant cell wall material. Owing to etching action of low energy beam to plant cell wall, ion beam mediated exogenous DNA transformation becomes possible. Representative applications and achievements in crop breeding were described.
Analysis of Sewage Heat Energy Application in Guiyang
Authors: Zhao Qi Ming , Zhu An , Jiang Xiu Ya , Long Jian
Published: May 2010

Reclamation and application of sewage heat energy is a good choice for sustainable development and an effective mean of energy-saving and output-reducing. By analyzing the capacity, temperature and quality of sewage of Guiyang, we obtained the basic conditions for the application of sewage heat energy in Guiyang. The results showed that the sewage of Guiyang was resourceful, and have occurrence of large amount of cold (hot) energy. There was an obvious temperature difference between sewage temperature and atmosphere temperature. Sewage was lightly corrosive. The application conditions of sewage heat energy were suitable. Sewage heat is a clean energy which is easy to recycle. Three factors, including capacity, temperature and quality of sewage, are considered if sewage heat energy was applied. 3 factors of 10 sewage treatment plants and their subsidiary pipe network in Guiyang were monitored and analyzed to verify the application conditions of sewage heat energy in Guiyang. From the perspective of energy-saving and output-reducing, an effective way is explored to develop new energy sources in Guiyang[1,2].
The Study of Weighted Association Rules and Using in the Maintenance of Engine CBR Design System
Authors: Yan Wei , Li Xue Qing , Tan Xu Guang , Tong De Hui , Gao Qi
Published: May 2010

In this paper, we propose a new technique of case-base maintenance. The weighted association-based case reduction technique (WACRT) can reduce the size of the case-base in order to enhance the efficiency while maintaining or even improving the accuracy of the CBR. The weighted association rules do not use the property “all subsets of a frequent item set are frequent”. It is pruned by the “k-support bound”. The experiments on the engine design system have shown superior generalization accuracy for CBR with WACRT as well as a greater solving efficiency.
Identification of Natural Frequencies and Dampings of the Bridge Deck Section Model Using the Combination Method of EMD and Wavelet Analysis
Authors: Chen G.F. , Zhang Zhe , Qiu Wen Liang
Published: May 2010

An accurate identification of the flutter derivatives of bridge deck section model in wind tunnel requires the information of dynamic properties of the bridge, including natural frequencies and damping ratios. This paper presents a method of identifying natural frequencies and damping ratios of the bridge deck section of different wind velocity. Firstly, we adopt the EMD technique to decompose the response signal of the model vibration into several mono-component signals which become analytic signal by means of Hilbert transform. Then each mono-component signal is analyzed via wavelet transform to identify the frequency and damping ratio. The results demonstrate that the combination method of EMD and Morlet wavelet transform can be used to identify the frequency and damping ratios effectively. The numerical simulation and the analysis of the response signal data from the bridge deck sectional model show that this method is effective.
The Non-Singularity on the Level-2(r1,r2)-Circulant Matrices of Type (n1,n2)
Authors: Zhao Wen Ling
Published: May 2010

As special matrices, it is well known that the circulant matrices are very important. Various types of circulant matrices have been applied in such as signal dealing and oil exploration, and so on in recent years. In this paper, motivated by [1], we give some discriminations by using only the elements in the first row of the Level- -Circulant Matrices of Type and parameter on non singularity, and give two examples at last.
Online Power Measurement and Prediction of PCs
Authors: Jiang Cong Feng , Zhao Ying Hui
Published: May 2010

Since more power consumption results in more failures and degradations in system performance, reliability, and power bills, it has been a critical problem for not only large scale server system but also personal computers (PCs). Though much literature has focused on energy management and power budgeting for server systems, power consumption of PCs does not attain sufficient attentions fairly. In this paper an online power measurement and prediction framework is proposed and used to save more energy considering the PC as a whole controlled system. The framework includes parts such as power measurement unit, power prediction unit and a simple execution unit of power reduction decisions. A hardware-software joint prototype is implemented based on an intelligent digital multimeter. Experiments on a desktop PC and a laptop show that PC with the framework can save more power consumptions than that of the PCs without this framework.
Research and Implementation of Smart Banknote Counter Self-Learning System
Authors: Feng Ji Qin , Wang Xian Quan , Lou Li Na
Published: May 2010

In the event of a new version of financial markets, realistic counterfeit money, and only rely on manufacturers to upgrade the software in order to re-identify the class counter counterfeit money, proposed to establish a banknote counter self-learning system. The article mainly describes the specific implementation method of banknote counter being on line self-learning ability, through establishing feature vector template database of banknotes, using the template matching algorithm to identify genuine and fake of banknotes. Experiments show that the smart banknote counter designed in the method has self-learning abilities for fake banknotes, can implement specific anti-counterfeiting, being greatly increase accuracy of identification falsity.
Reinforcement Mechanism of the Deep Buried Piles by Large Scaled Model Tests
Authors: Lei Wen Jie , Zheng Yin Gren , Song Ya Kun
Published: May 2010

Series of large scaled model test has been carried out to examine the reinforcement mechanism of deep buried piles. Testing tools including rigid load cells, the earth pressure cells and data collecting systems are employed to measure the anti-thrust received by deep buried piles and the slope thrust of the slope on piles top. On the basis of the variation process of measured data, the time and the location of slide surface in the slope is determined, and the maximal anti-sliding force upward to the piles top could be gained by the data of earth pressure cells. Then the failure form process is analyzed with the anti-sliding length of the piles changed. The relationship between the sliding force received by the piles and that supplied by the slope on piles top is analyzed to supply scientific demonstration for the design method of slope reinforced by the deeply buried piles.
Research on Three-Dimensional Description and Measurement of Government Investment Project Risk
Authors: Ding Rong Gui , Liu Xing Zhi , Sun Hua
Published: May 2010

With the increase in the size of government investment projects, an increasing number of uncertain factors are involved and the risks are increasingly complex, the project risks can accurately describe and measure the project will directly affect the investment decision-making and project management. To this end, respectively, analyze two-dimensional method and multi-dimensional method and Put forward a three-dimensional description method, describing project risk thoroughly from the probability, losses as well as manageability. On this basis the risk function is established, and finally an example is given. The results showed that three-dimensional structure not only take into account both qualitative and quantitative, at the same time taking into account the subjectivity and objectivity of risk, a more accurate reflection of the true face of government investment project risk.
Review of Channel Characterization for Power Line Communications
Authors: Huang Nan Tian , Liu Xiao Sheng , Xu Dian Guo
Published: May 2010

The power line communication (PLC) channel has been a transmission medium that enables to transfer high-speed digital data through the classical electrical wires. Channel characteristics of power lines are very important for communications systems design. In order to get the suitable model for power line communications analysis and improve the PLC communication quality, researchers do lots of study about the PLC channel characterizations based on actual measurement and theoretical analysis. This paper reviews the conclusions of recent studies, summaries the characteristics of PLC channel for medium voltage power lines and low voltage power lines. The further research is also put forward.
Analysis of Safety Index System on Road Transport of Dangerous Goods
Authors: Meng Xiang Ru
Published: May 2010

With the improvement of national economy and living standards of the people，the demand for transport of dangerous goods is greater and greater, the traffic volume of the road dangerous goods is rising constantly. The accidents of road transport of dangerous goods happen frequently, the extent of injury that the accident causes is more and more serious, the accidents destroy and pollute the environment seriously，threaten people’s lives and properties seriously, cause the serious economic losses. This papter is to set up the indicator system of safety evaluation of road transport of dangerous goods, and put forward the countermeasure of our country’s road transport of dangerous goods pointedly, offer real guidance for carrying on road transport of dangerous goods, reduce the emergence of traffic accident of road transport of dangerous goods.
Structured-Light-Based 3D Reconstruction Using Gray Code and Line-Shift Stripes
Authors: Zheng Shun Yi , Hu Hua Liang , Xu Xuan , Le Kai
Published: May 2010

The structured light can be used to extract the 3D information through obtaining the three-dimensional points from being measured object, and this method is simple, fast and accurate. However, the key factor of this process is how to inspect the stripes accurately. To improve the accuracy, in this paper, we firstly locate the stripes of the structured light roughly by use of the gray code images, and then locate it accurately by utilizing the line-shift stripes code images. Finally we turn the two dimensions search into one dimension search in the image match by using of epipolar constraint, and the intersection points of the stripes of structured light and the epipolar line are final match points. Finally, space intersection has been used to obtain three-dimensional points. Repeated experiments prove that wonderful effect can be obtained by this method.
Error Analysis of LMS200 in Distance Measuring Application
Authors: Sui Jin Xue , Yang Li , Zhu Zhi Lin , Hua Zhen
Published: May 2010

The laser ranging has far detection range and high measurement accuracy and so on merits, is widely applied to navigation system of the autonomous robot, but different environmental conditions have different influence on transmission of the laser, producing errors of the various degree to measurement. Proposed ranging influence research of the laser ranging LMS200 which is used in the robot navigation under the dissimilar condition, through analyzing primary factor that affect LMS200 ranging in the room and outside, and makes the experimental contrast, obtains experimental effect under environmental influencing factor, discovers reflectivity, incidence, mixed pixel and visibility and so on environmental factor which effect on practical application truly, builds the foundation for carrying on ranging application of the robot navigation.
The Application of Support Vector Regression Method for Solving the Inverse ECG Problem
Authors: Jiang Ming Feng , Wang Chen Qun , Huang Wen Qing , Cai Xia
Published: May 2010

The problem of noninvasive computing the epicardial surface potentials from torso surface potentials constitutes one form of the inverse problem of ECG, which can be acted as a regression problem with multi-input and multi-output. In this study, the SVR method is invoked to predict the inverse solutions, which compared with the common regularization methods. To build an effective SVR model, the hyper-parameters of SVR are set carefully by using the grid search optimization method. The experiment results shows that SVR method is an effective way for solving the inverse ECG problem, which can reconstruct more accurate epicardial surface potentials distribution than the common regularization method, such as Tikhonv method and LSQR method.
The Analyzing Technique of Program Based on Program Slicing
Authors: Liu Shu Kun , Yang Xiao Hua
Published: May 2010

Program analysis plays an important role in software development and maintenance. With this method, characteristics of every variable in program can be analyzed. During the period of program analyzing, computing the program slicing by the method of constructing system dependence graph is an efficient way but the work of constructing the system dependence graph is very complicated which often leads to many wrong results. So the algorithm of hierarchy slice is used in this paper. Using the precise results, the whole program can be analyzed and the dependence relation in the program can be discovered quickly.
Fuzzy Evaluation of Synthetic Quality for Fabric Materials
Authors: Wang Xiu Chen
Published: May 2010

Aaccording to the cases that the synthetic quality evaluation system for fabric is not reasonable at present, a new synthetic quality evaluation system for fabric on fuzzy theory is proposed. This new evaluation system is made of foundation layer, evaluating layer and result layer. In foundation layer, the quality standard model and evaluating data model based on multi-indexes are proposed, and the calculation method of each index value in these models is given. In evaluating layer, according to the problem that the result of existing closeness algorithm has greatly repeated, a new evaluation algorithm is proposed. In result layer, two formulas which are continuous result and discrete result are given. Also the accuracy and rationality of this evaluation system is validated by some examples in this paper, and the effect of evaluation result by the primary-secondary indexes, the significance of closeness, the expansibility of model, the accuracy of system and the application method are made analysis. At last, the conclusion shows that this system can make the synthetic evaluation for fabric quality rationally and accurately.
Modeling and Test of New Energy of Low-Temperature Fuel Cells with Multiple Inputs Multiple Outputs
Authors: Tian Yu Dong
Published: May 2010

The low-temperature fuel cell is a difficulty in the basic research field of new energy at present, and its strict running status influences the performance and life of the cell greatly. To aim at the problem, an electrical model of low-temperature fuel cells was advanced based on electrochemical mechanism. Then, the modeling structure, algorithm, optimization, test and experiment of low-temperature fuel cells were particularly presented applied the electrical characteristics equation. Finally, the experimental results provided the suitable model of fuel cells hybrid power system at the view of application.
Comparative Study of Nanyang Road Network by GIS
Authors: Li Rui , Bing He , Song Jing Hua
Published: May 2010

A comparative method for studying road network based on GIS will be proposed in this paper, in which Axwoman is involved as an ArcView extension for urban morphological analysis. Finally, the case of Nanyang city is applied to show the expansion of road network in 1984, 1996 and 2008, by comparing the changes of global integration value, local integration value and connectivity value of whole city, special roads and different sub-areas respectively.
Bidirectional Fractal Test of Dust Particle
Authors: Jiang Fan , Chen Wei Ping , Liang Zhong Wei
Published: May 2010

To describe surface shape of the dust particle comprehensively, uses the bidirectional CCD to shoot picture of dust particle, through recognizing the bidirectional particle picture, matching the particle, computing the fractal results of identical particle in two pictures, and integrating two fractal results, obtains the dust particle bidirectional fractal. The results indicated that three fractal dimensions of spherical particle are quite closed, but the three fractal dimensions of flat type particle are significantly different.
Development of a GSP Integrated Formative Assessment System on Geometric Creativity
Authors: Chen Yuan , Hung Pi Hsia
Published: May 2010

A GSP integrated learning and assessment system (LAS-GSP) is developed to provide students an interactive exploration environment and on-line feedbacks on geometric problem solving. Three tasks of maximal segmentation are developed to investigate the applicability and intervention effect of the system. There are four scoring elements for students’ on line assignments: (1) systematic approaches, (2) correct solutions, (3) originality of representation, and (4) function derived. The characteristics of students’ learning progress are discussed by the scoring rubrics applied. The results suggest abstract geometric concepts can be visualized, internalized, and enhanced at an earlier age, if mind-tool can be effectively implemented.
Improvement of Autonomous Learning Abilities of Linguistic Learners Based on Information Technology
Authors: Tian Xian Zhi
Published: May 2010

Autonomous learning abilities plays an important roles in linguistic learning course. Nowadays, with development of modern information technology and teaching reform in universities, improvement of autonomous learning abilities becomes more and more important for linguistic learners. It is teachers' responsibilities to improve autonomous learning abilities of students with a large variety of measures and strategies. Therefore, the author puts her efforts on studying teaching measures and strategies for improving teaching efficiencies. How do teachers make his or her measures be scientific and effective? How do teaching measures stimulate students and promote students ? How do students turn their learning into autonomous learning ? All of those questions should be probed by researchers and teachers. In the paper, the author tries her best to solve those problems and tries to find out effective teaching strategies for improvement teaching efficiencies.
Effect of Fiber Treatment on Fiber Strength and Fiber/Matrix Interface of Hemp Reinforced Polypropylene Composites
Authors: Bouzouita Sofien , Salvia Michelle , Ben Daly Hachmi , Dogui A. , Forest E.
Published: May 2010

The use of natural fibers as reinforcement in composites is emerging. Several studies are underway to improve the mechanical characteristics of these fibers and its matrix interface properties for better load transfer. However, the treatments generally used are relatively expensive and complicated to apply. This work deals with the effect of new Fibroline process on tensile and interfacial properties of hemp fiber reinforced in polypropylene. Fibroline is a dry powder impregnation method which consists of submitting fibers and polymer powder under strong alternating electric field. Morphology and tensile properties of hemp fibers after different surface treatments (raw, dried, raw and Fibroline-treated, dried and Fibroline-treated) are evaluated. Interface properties of treated hemp fibers on polypropylene matrix are then characterized by fragmentation test of monofilament composites. Results showed the Fibroline treatment reduces the fiber mechanical properties but improves the load transfer efficiency due to random generation of surface cracks and better fiber/matrix adherence, respectively. For the case of dried and Fibroline-treated hemp fibers, large decrease in mechanical and interfacial properties was observed.
Synthesis and Electrical Characterization of Multilayer Thin Films Designed by Layer-by-Layer Self Assembly of Nanoparticles
Authors: Promnimit Sujira , Dutta Joydeep
Published: May 2010

In this work, we report the directed self organization of multilayer thin film devices with colloidal nanoparticles through Layer-by-Layer (LbL) technique [1]. Self-organization of nanoparticles into assemblies to create novel nanostructures is getting increasing research attention in microelectronics, medical, energy and environmental applications. Directed self-organization of nanoparticles [2] into multilayer thin films were achieved by LbL growth through the interaction of oppositely charged of colloidal nanoparticles on substrates of any kind and shapes. Multilayer thin film devices were fabricated using multilayers of gold (conducting) nanoparticles separated by a dielectric nanoparticulate layer of zinc sulphide. The thin films obtained have been studied extensively and the changes in surface morphology, the optical absorption characteristics, thickness, uniformity, adhesion, and conduction behavior are reported. Current voltage (I-V) characteristics of multilayer devices with an increasing number of deposition cycles show an initial current blockade until an onset voltage value, which increases linearly upon the additional layers stacked in devices [3]. A conductive behavior of the device was observed upon exceeding the onset voltage. Moreover, I-V behavior showed that the conduction onset voltage increases linearly depending on the numbers of layers in the final device controlled by the deposition cycles. Systematic I-V characteristics in the forward and reverse biased conditions demonstrated rectifying behaviors in the onset of conduction voltage which makes these films attractive for future electronic device applications.
Adsorption Properties of Surface Modified Carbons with Metal Nanoparticles
Authors: Miyajima N. , Takagi H. , Yamada Y. , Hatori Hiroaki
Published: May 2010

The effect of surface modification by nanoparticles of metal compounds was investigated by means of gas and vapor adsorption analysis. The surface of activated carbon fiber cloths was modified by loading of Li2CO3 and MgO nanoparticles. The particles on the carbon surface played as initial adsorption site of water molecules, leading to the promotion of micropore filling without diminishing the micropore volume of the porous carbon supports. The increasing characteristic adsorption energy suggested some interaction between methane molecules and the particles.
Electron-Phonon Interactions and Vibrational Modes in Insulating Nanocrystals
Authors: Ha M.G. , Jeong E.D. , Hong K.S. , Yang H.S.
Published: May 2010

The temperature and particle size dependence of the holewidths for the 7F0 → 5D0 transition of Eu3+ ions in Eu2O3 are calculated and compared with experiment. The calculation is able to describe the effect of nanocrystal vibrational modes on the dephasing of the electronic states of probe ions. The nanocrystal was treated as an elastically isotropic sphere from which the acoustic phonon displacements and phonon spectrum were calculated. Then we applied this to the temperature and size dependencies of the electron-phonon interaction. Also the vibrational modes in nanocrystals are discussed.
Enhanced Li-Transport on the Nanoscale: TiO2-B Nanowires
Authors: Koudriachova Marina V.
Published: May 2010

The origin of enhanced intercalation of Li-ions into TiO2-B is being examined using first principles density functional calculations. Using advanced simulation techniques, we built a comprehensive description of Li-intercalation into TiO2-B and demonstrate that it acts as a capacitor at [Li]/[Ti] ≤ 0.5, while at higher concentrations the insertion capacity is limited by Li self-diffusion.
Synthesis and Optimization of TiO2 Nano Crystals by Gel-Casting Method
Authors: Rohani A.A. , Tabrizi M. , Manafi S. , Badiei H.
Published: May 2010

In this study, titania (TiO2) nano powders were synthesized by a new method. TiO2 nano-sized powders were prepared by a gel-casting method. Crystalline structure, morphology and mineral phase analysis of TiO2 powder have been characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Results show that different preparation conditions of gel such as reactants concentration, accelerator, starter concentration, time and temperature of calcination have a large influence on the properties of the produced powder. Calcination time and temperature can improve the crystallization of TiO2 powders and can be an accelerator factor for converting amorphous phase to anatase or rutile phase. The results obtained show that the anatase to rutile transformation is started at about 750oC and the best size of produced powder grain is 20-25 nm.
The Impact of Diffusion on Synthesis of High-Strength Titanium Alloys from Elemental Powder Blends
Authors: Ivasishin Orest M. , Savvakin Dmytro G.
Published: May 2010

High strength near-beta titanium alloys are being increasingly used in industry due to their excellent combination of properties. Blended elemental powder metallurgy (BEPM) allows to produce the above alloys and parts from them in a cost-effective manner. However, the alloy synthesis is complicated by a big amount (up to 18 wt.%) of alloying elements which diffusional redistribution between alloying particles and titanium matrix has a strong impact on microstructure evolution. In this paper synthesis of the high-strength alloys from the powder blends based on hydrogenated titanium was studied. It was found that hydrogen strongly affects diffusion controlled processes upon synthesis, such as chemical homogenization, densification and grain growth through its influence on phase composition and defect structure of the blends. Optimization of the processing parameters allowed to produce uniform, nearly-dense alloys with reduced grain size, which mechanical properties met the requirements of corresponding specifications.
Investigation of Pressing and Sintering Processes of CP-Ti Powder Made by Armstrong Process
Authors: Chen Wei , Yamamoto Yukinori , Peter William H.
Published: May 2010

This work used in-situ and ex-situ techniques to investigate the pressing and sintering processes of commercially pure (CP) Ti powder made by the Armstrong process. The objective is to simulate the actual manufacturing process of near net shape Ti components. Ti powders were uniaxially pre-pressed at designated pressures up to 100 ksi to form disk samples with different theoretical densities. Compression tests were performed in an SEM at different temperatures to obtain the mechanical properties and deformation behavior of these samples. Ex-situ technique was used to track the powder deformation process of disk samples from low pressure to high pressure. In-situ sintering was also performed in an SEM to record the morphology change of the porosities on the sample surface during the sintering process. The results will provide valuable information for optimizing the manufacturing process of high-density near net shape Ti components.
The FFC-Cambridge Process for Titanium Metal Winning
Authors: Schwandt Carsten , Doughty Greg R. , Fray Derek J.
Published: May 2010

The FFC-Cambridge process is a molten salt electrochemical deoxidation method that was invented at the Department of Materials Science and Metallurgy of the University of Cambridge one decade ago. It is a generic technology that allows the direct conversion of metal oxides into the corresponding metals through cathodic polarisation of the oxide in a molten salt electrolyte based on calcium chloride. The process is rather universal in its applicability, and numerous studies on metals, semimetals, alloys and intermetallics have since been performed at the place of its invention and worldwide. The electro-winning of titanium metal is a particularly rewarding target because of the disadvantages of the existing extraction methods. This article summarises the research work performed on the FFC-Cambridge process at the University of Cambridge and its industrial partners with a focus on the electro-winning of titanium metal from titanium dioxide. Topics addressed encompass the invention of the process, early proof-of-concept work, the identification of the reaction pathway, and the investigation and optimisation of the key process parameters. Also discussed are aspects of technology transfer and some of the development work undertaken to date.
Reaction Assisted Ultrasonic Consolidated TiNi
Authors: Kulakov M. , Rack Henry J.
Published: May 2010

This investigation has examined the feasibility of fabricating near-net shape components containing TiNi shape memory constituents by combining the attributes of ultrasonic consolidation and reaction heat treatment. An optimization design of experiment was conducted to determine the ultrasonic consolidation control parameters, e.g., sonotrode rotational velocity, amplitude and normal force, which would result in the maximum weld quality as defined by the linear weld density. Subsequent thermal treatment of the consolidated compact resulted in the formation of a graded Ti-TiNi-Ni microstructure.
Titanium and Titanium Alloy via Sintering of TiH2
Authors: Wang Hong Tao , Lefler Michael , Fang Z. Zak , Lei Ting , Fang Shu Ming , Zhang Jia Min , Zhao Qun
Published: May 2010

Blended elemental (BE) powder metallurgy (PM) is a promising low cost approach for manufacture titanium and titanium alloy components. Conventional BE method relies on sintering of pure titanium metal powder, while the new approach examined in this investigation produces bulk titanium materials by sintering titanium hydride powder. Dehydrogenation and densification of TiH2 powders with different particle sizes and TiH2-6Al-4V alloy powder was studied using thermogravimetric and dilatometric techniques. The results show that the dehydrogenation of TiH2 leads to very rapid shrinkage of α-Ti during sintering. In contrast, densification TiH2-6Al-4V requires dissolution of alloy elements which occurs during sintering above its beta transus temperature.
Mechanical Performance of Heat Treated Ti-6Al-4V Friction Stir Welds
Authors: Edwards Paul , Petersen Marc , Ramulu Mamidala , Boyer Rodney
Published: May 2010

Heat treatment processes for standard fusion welding techniques in titanium are well established, but the optimal heat treatment for Friction Stir Welded titanium has not been evaluated. In this study, 6 mm thickness titanium 6Al-4V butt welds were subjected to heat treatments ranging from 700 to 900 C. Results of the metallographic analysis for each heat treatment condition will be presented in addition to microhardness, tensile and fatigue properties. It was found that increased heat treatment temperatures lead to lower hardness and tensile strengths, higher elongation to failure and improved high cycle fatigue performance. Furthermore, fracture toughness and crack growth tests were performed for welds subjected to a standard post-weld stress relief. The fracture toughness was lower than the parent material, but crack growth rates in the weld were similar to that of the base metal.
Electrochemical Production of Titanium from Oxycarbide Anodes
Authors: Kjos Ole Sigmund , Haarberg Geir Martin , Martinez Ana Maria
Published: May 2010

The aim of this work was to improve the quality of the produced titanium at the cathode in electrolysis experiments using a titanium oxycarbide anode, which is made of a solid solution of TiC and TiO. Two different approaches were tested: solid titanium deposition from a NaCl-Na3AlF6 electrolyte, and a standard NaCl-KCl electrolyte with a liquid metal cathode producing a titanium alloy.
Comparison of Inversion Layer Electron Transport of Lightly Doped 4H and 6H SiC MOSFETs
Authors: Tilak Vinayak , Matocha Kevin , Dunne Greg
Published: May 2010

nversion layers of 4H and 6H Silicon carbide based MOS devices are characterized by
Gated Hall measurements to determine the trap density close to the conduction band edge and the
main scattering mechanisms that limit the mobility. MOS gated Hall structures were fabricated on
4H SiC polytype with p-type doping of 5X1015cm-3 and 2X1017cm-3. MOS Gated Hall structures
were also fabricated on 6H SiC polytype with p-type doping of 7.5X1015cm-3. The gate oxide was
grown thermally with N2O as a precursor followed by a NO post oxidation anneal. The inversion
layer Hall mobility on the 6H SiC MOSFET sample decreased with increasing temperature from
room temperature to 423K, while on the 4H SiC MOSFET samples the inversion layer mobility
increased slowly. Approximately 50% of the total charge density at the interface of both 6H and 4H
SiC MOSFETs was found to be trapped charge. The dominant scattering mechanism in 6H SiC
MOSFETs was inferred to be phonon scattering based on the temperature dependence and
theoretical estimates of the phonon limited mobility. In the case of 4H SiC, we infer that at surface
roughness scattering is the dominant scattering mechanisms at high surface fields.
Current Transient Effect in N-Channel 6H-SiC MOSFET Induced by Heavy Ion Irradiation
Authors: Lee Kin Kiong , Laird Jamie Steward , Ohshima Takeshi , Onoda Shinobu , Hirao Toshio , Itoh Hisayoshi
Published: May 2010

This paper investigates the transient induced currents by energetic carbon ions in 6H-SiC MOSFETs and the carrier dynamic response due to such a heavy ion collision is simulated by Technology Computer Aided Design (TCAD). It was found that a heavy ion strike induces a bipolar effect on the transistor, whereby the current transients can vary in both polarities. And this has been attributed to the inherent in the MOSFET is a parasitic bipolar junction transistor.
Large Area >8 kV SiC GTO Thyristors with Innovative Anode-Gate Designs
Authors: Sundaresan Siddarth G. , Issa H. , Veeredy Deepak , Singh Ranbir
Published: May 2010

This study is focused on the design and fabrication of large-area (4.1x4.1 mm2 and 8.2x8.2 mm2), 8.1 kV 4H-SiC GTO Thyristors. The anode and gate fingers of Thyristors were designed with involute, cellular or hexagonal patterns. Forward blocking voltages as high as 8106 V and On-state voltage drop (Von) and differential specific on-resistance (Ron,sp) as low as 3.8 V and 6 mΩ-cm2 at 100 A/cm2 were measured on these devices. About 59% of 4.1 x4.1 mm2 and 29% of 8.2x8.2 mm2 Thyristors blocked voltages in excess of 6 kV. Detailed investigations revealed the impact of different anode/gate finger geometries on the device characteristics. Preliminary pulsed power characterization of the GTO Thyristors was also performed.
Epitaxial Growth of 4H-SiC with High Growth Rate Using CH3Cl and SiCl4 Chlorinated Growth Precursors
Authors: Kotamraju Siva Prasad , Krishnan Bharat , Koshka Yaroslav
Published: May 2010

Thick 4H-SiC epitaxial layers have been grown using a combination of two chlorinated precursors silicon tetrachloride (SiCl4) and chloromethane (CH3Cl) at 16000C. Growth rates up to 100 m/hr have been demonstrated. The use of chloro-silane precursor eliminated the problem of homogenous nucleation of Si in the gas phase, which was significant in CH3Cl/SiH4 growth. Much higher values of Si/H2 and C/H2 ratios without morphology degradation were made possible by increasing the growth temperature from 1300 to 1600°C. Results of photoluminescence and high-resolution X-ray diffraction and time-resolved PL were used to evaluate the quality of the epitaxial layers. The crystalline quality and the growth rate achieved so far offer a promise of exceeding the state of the arts results achieved with more traditional hydro-carbon precursors.
2.2 kV SiC BJTs with Low VCESAT Fast Switching and Short-Circuit Capability
Authors: Domeij Martin , Zaring Carina , Konstantinov Andrei O. , Nawaz Muhammad , Svedberg Jan Olov , Gumaelius Krister , Keri Imre , Lindgren Anders , Hammarlund Bo , Östling Mikael , Reimark Mats
Published: May 2010

This paper reports large active area (15 mm2) 4H-SiC BJTs with a low VCESAT=0.6 V at IC=20 A (JC=133 A/cm2) and an open-base breakdown voltage BVCEO=2.3 kV at T=25 °C. The corresponding room temperature specific on-resistance RSP-ON=4.5 mΩcm2 is to the authors knowledge the lowest reported value for a large area SiC BJT blocking more than 2 kV. The on-state and blocking characteristics were analyzed by device simulation and found to be in good agreement with measurements. Fast switching with VCE rise- and fall-times in the range of 20-30 ns was demonstrated for a 6 A 1200 V rated SiC BJT. It was concluded that high dynamic base currents are essential for fast switching to charge the BJT parasitic base-collector capacitance. In addition, 10 μs short-circuit capability with VCE=800 V was shown for the 1200 V BJT.
A 10 kV 4H-SiC Bipolar Turn Off Thyristor (BTO) with Positive Temperature Coefficient of VF, Current Saturation Capability and Fast Switching Speed
Authors: Zhang Qing Chun Jon , Richmond Jim , Capell Craig , Agarwal Anant K. , Palmour John W. , O'Brian Heather , Scozzie Charles
Published: May 2010

A novel power device configuration, the Bipolar Turn Off thyristor (BTO), was proposed and demonstrated in SiC. The BTO operates in anode switch configuration consisting of a 9 kV SiC p-type Gate Turn Off thyristor (GTO) and a 1600 V SiC n-type Bipolar Junction Transistor (BJT). Compared with SiC GTOs, several new features have been accomplished in the BTO: (1) A positive temperature coefficient of forward voltage drop, (2) Anode current saturation capability, and (3) A simple gate driver and fast switching speed.
3kV 4H-SiC Thyristors for Pulsed Power Applications
Authors: Elasser Ahmed , Losee Peter A. , Arthur Steve , Stum Zachary , Matocha Kevin , Dunne Greg , Garrett Jerome L. , Schutten Michael , Brown Dale
Published: May 2010

Due to the Silicon Carbide (SiC) material’s high electric field strength, wide bandgap, and good thermal conductivity, 4H-SiC thyristors are attractive candidates for pulsed power applications. With a thinner blocking layer almost an order of magnitude smaller than its Silicon (Si) counterpart, these devices promise very fast turn-on capabilities as full conductivity modulation occurs >10 times faster than comparable silicon thyristors, low leakage currents at high junction temperatures and at high voltage, and much lower forward voltage drop at high pulse currents. Our progress on the development of large area (4mm x 4mm) SiC thyristors is presented in this paper.
Improvement of Current Gain with Etched Extrinsic Base Regions of Triple Ion Implanted SiC BJT
Authors: Tajima Taku , Nakamura Tohru , Watabe Y. , Satoh Masataka , Nakamura Tadashi
Published: May 2010

In this paper, we demonstrate triple ion implanted 4H-SiC bipolar junction transistor (BJT) with etched extrinsic base regions. At the result of etching extrinsic base regions by mask of contact metals, maximum common emitter current gain was improved from 0.7 to 1.6.
Performance of Silicon Carbide Avalanche Photodiode Arrays and Photomultipliers
Authors: Vert Alexey V. , Soloviev Stanislav I. , Sandvik Peter M.
Published: May 2010

We present recent results on 4H-SiC avalanche photodiode arrays and SiC-based solid-state photomultiplier arrays suitable for ultraviolet and solar-blind light detection. A novel SiC-based photomultiplier array was demonstrated. An additional solar-blind filter enabled a solar photon rejection ratio of more than 106 in combination with 40% quantum efficiency at 280 nm.
Optical Properties of Antireflective Subwavelength Structures on 4H-SiC for UV Photodetectors
Authors: Hirabayashi Yasuo , Kaneko Satoru , Akiyama Kensuke , Yasui Manabu , Sakurazawa Keitaro
Published: May 2010

For the purpose of the improving the efficiency of the 4H-SiC photodiode, we reported the spectral reflectance of the antireflection structure of the 140nm period like Moth Eye structure on the 4H-SiC pn epi-wafer. Measured reflectivity of the antireflection structured surface is below 2% at 310nm. The peak responsivity of SWS photodiode is 170mA/W (QE=75%) at 280nm. The response cut-off wavelength is 380nm. Sensitivity of the sensor with SWS structure has increased by compared with that without SWS structure over 260nm of wavelength. At 310 nm, the sensitivity of the photodiode with SWS has increased by 1.3 times than that without SWS. Total amount of short circuit currents was 22% of increase.