bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Realization of Fault Injection Based on CTCS-3 Simulation
Authors: Gou Chen Xi , Cai Bai Gen , Tang Tao , Wei Shang Guan
Published: January 2010

Reliability of CTCS-3 train operation and control system is necessary to ensure train running safely and efficiently. Thus, train control system simulation should be used for lots of tests and validations. This paper is focus on the theory and period of fault injection systematically. According to characters of simulation of train control system and advantages of fault injection, application of fault injection in the field of train control system simulation is proposed for reliability test and to obtain system information after fault injection. Main structure and detailed functions, structures of fault injection system is designed and realized. This system could simulate system fault to cause rapid failure in train control system during the experiment. By analyzing the simulation result, the conclusion could be obtained that application of fault injection could help to improve reliability and fault tolerance of C3 simulation.
A Research Combining Spatial Filter with Autoregressive Model for EEG Feature Extraction
Authors: Liu Lin , Wei Qing Guo
Published: January 2010

In a noninvasive brain-computer interface (BCI), EEG feature extraction is a key part for improving classification accuracy and resulting information transfer rate, and it has a crucial and decisive role. In this paper, three different methods were proposed that combine spatial filtering with autoregressive model for EEG feature extraction. Six subjects participated in the BCI experiment during which they were asked to imagine movements of left hand and right hand. Each subject carried out four sessions and each session contained 120 trials. EEG data recordings were used for off-line analysis and the 10 leads around C3 and C4 were chosen for feature extraction. Autoregressive model coefficients and the parameters derived from other three methods were proposed as classification features. Fisher discriminant analysis (FDA) was used as linear classifier. The results show that classification accuracy rates obtained from the three proposed methods are far higher than those acquired from autoregressive model coefficients. At the same time the classification results of each subject are very stable, proving the effectiveness of these novel feature methods.
A Novel Quantum Neural Network Model with Variable Selection for Short Term Load Forecasting
Authors: Sun Wei , He Yu Jun , Meng Ming
Published: January 2010

The paper presents a novel quantum neural network (QNN) model with variable selection for short term load forecasting. In the proposed QNN model, first, the combiniation of maximum conditonal entropy theory and principal component analysis method is used to select main influential factors with maximum correlation degree to power load index, thus getting effective input variables set. Then the quantum neural network forecating model is constructed. The proposed QNN forecastig model is tested for certain province load data. The experiments and the performance with QNN neural network model are given, and the results showed the method could provide a satisfactory improvement of the forecasting accuracy compared with traditional BP network model.
An Effective Chaotic Cultural-Based Particle Swarm Optimization for Constrained Engineering Design Problems
Authors: Zhou Yong Quan , Liu Lingzi
Published: January 2010

In this paper, a novel chaotic cultural-based particle swarm optimization algorithm (CCPSO)
is proposed for constrained optimization problems by employing cultural-based particle swarm
optimization (CPSO) algorithm and the notion of chaotic local search strategy. In the CCPSO, the
shortcoming of cultural-based particle swarm optimization (CPSO) that it is easy to trap into local
minimum be overcome, the chaotic local search strategy is introduced in the influence functions of
cultural algorithm. Simulation results based on well-known constrained engineering design problems
demonstrate the effectiveness, efficiency and robustness on initial populations of the proposed method.
An Optimized LCP Table Based Algorithm for Frequent String Mining
Authors: Guo Zhan Xi , Ma Zhi Xin , Xu Yu Sheng , Liu Li
Published: January 2010

Given m databases D1,...,Dm of strings, the purpose of the frequent string mining is to find all strings that fulfill certain constraints of all string databases. In this paper, a useful data structure is proposed to construct suffix and LCP table which can reduce the total space consumption of string mining efficiently. We demonstrate the use of this data structure by optimizing the algorithm proposed by A.Kügel et al [7] and present the improved algorithm. It is achieved that the space consumption in our algorithm is proportional to the length of the largest string of all databases. A set of comprehensive performance experiments shows that the processing rate is enhanced because amount of items are reduced in new data structure.
The Assessment Method of Supply Chain Risks Based on Vague Sets
Authors: Zhao Ai Wu , Guan Hong Jun
Published: January 2010

In order to evaluate the supply chain risks, proposed the combination method based on Vague Sets and fuzzy risk assessment, and took an application model for example. First introduced the basic knowledge about fuzzy mathematics and Vague sets. Then gave the model of risk assessment and its algorithms, determined the major risk factors using Vague set theory and fuzzy mathematics method, combined the expert evaluation and fuzzy switch, applied the fuzzy analysis method to the static risk assessment of suppliers’ risks and the individual risk status assessment of special event. Finally, described the specific flow by an example.
A PCA Based Fault Detection and Isolation Method for Train Locating System
Authors: Liu Jiang , Cai Bai Gen , Tang Tao , Wang Jian
Published: January 2010

Fault tolerance is crucial to the operating safety and performance of train locating system. Based on the requirements of reliability and safety for train locating, the fault characteristics of location measuring sensors are analyzed. Based on the structure of the train locating system, the fault-tolerant design of the system is given with the location filtering module for case, in which six fault detectors are employed to determine the configuration of the module. Then a PCA based fault detection and isolation method is proposed with Hawkins T2 statistics and the corresponding control limit. By dynamically adjusting the efficiency factors, fault could be detected and isolated as prior defined isolating strategies, and then the fault tolerant performance will be guaranteed. Simulation results demonstrate the high fault tolerant ability of the proposed approach and certain practical application value.
Research on the Problems and Strategies for the Community Informationization Construction in the Process of Digital City
Authors: Yang Jing , Sun Xiao Fei
Published: January 2010

Community informationization has become one of the most active and attracting fields in city informationization. It attracts large amounts of capital, technology and talents. The governments, companies and community residents pay much attention to it. To construct community informationization is not only one issue of city informationization, but also is the basis and an important part of city informationization construction. The paper has made a conclusion and research on the problems existing in the construction of community informationization in connection with the process of present city informationization construction. Furthermore, relevant strategies and advice are presented according to the existing problems, providing some help to the community informationization construction in the city informationization construction.
Application of ANN Algorithm in Tree Height Modeling
Authors: Li Yao Xiang , Jiang Li Chun
Published: January 2010

Back-propagation (BP) algorithm of artificial neural network (ANN) was applied to tree height prediction of Larch plantation in northeast China by taking logsigmoid function of logsig and linear function of purelin in Matlab as the neural functions. One input variable of tree diameter and one output variable of tree height was used in the model with one hidden layer of 5 hidden neurons. Model developed was evaluated graphically and statistically. Results showed that model performs well with mean square error (MSE) of 0.130901 and model precision of 97.6%. The graphical comparisons between the actual measured data and the network predicted output clearly demonstrate very good agreement between the actual and predicted performance.
Intelligent Method in the End-Point Control of BOF
Authors: Peng Kai Xiang , Zhang Jun , Dong Jie
Published: January 2010

The design of BOF in Jiangyin Xingcheng Special Steel Co. Ltd is based on static and dynamic model. The BOF end-point carbon content and temperature are predicted by means of BP neural network. On basis of that, the consumption of material, output of static model, are regulated according to the prediction result. The shortcoming that the theory on static model is imperfect is overcome. The end-point hit rate is raised effectually in industrial practice.
Enumeration Based Security Behavior Model Checking Algorithm
Authors: Liu Hua Xiao , Jin Ying
Published: January 2010

Model Carrying Code(MCC) provides a way to safe execution of untrusted code by
taking both mobile code producer and consumers into consideration, where it checks mobile code
security by comparing security related program behavior model with security policies. In this paper
an enumeration based algorithm to checking security related behavior with respect to security
policy has been given, where security behavior has been modeled as extended context free grammar
and the security policy has been specified as extended FSA. Solutions to dealing with loops and
recursions have been introduced. A program has been developed for implementing the algorithm,
and several experiments have been done. It has been indicated that our algorithm can effectively
check small scale security behavior models on the basis of simple security policies.
Principles for Process Reengineering of Manufacturing Logistics
Authors: Xie Ke Fan , Wu Qian , Chen Yun
Published: January 2010

Developing modern logistics is a vital road for realizing successful
manufacturing enterprises. This paper analyzes three principles of process
reengineering of manufacturing logistics: economy principle, agility principle, and
synergy principle. Afterwards, the paper takes Dongfeng Automotive Fasteners
Limited Corporation(DAFLC, a son company of Dongfeng Automobile Co. Ltd) as a
case to analyze the routes of the process reengineering of manufacturing logistics.
Based on the three principles, the process reengineering of the purchasing process,
distribution process, and storage process of DAFLC achieves distinctive effect.
A Semantic Web Service Discovery Method Based on Ontology
Authors: Tian Wen Ya , Xu Zhu Jun
Published: January 2010

Many methods have been used such as UDDI and DWS to discovery requested web services. But they are just a kind of simple syntax match based on keywords and have a low ratio and precision. This paper proposes A Semantic Web Service Discovery Method Based on Ontology. It uses tree-form data structure to describe the web services and give all the nodes a weight value by certain strategy, then compute the semantic similarity between the web services requested and the services registered. To validate the feasibility and effectiveness of the algorithm, we construct a self-developed prototype system to show how well it works. The experiments prove that this algorithm has high recall and precision than other methods.
An Empirical Study of the Construct of Information Systems Strategy
Authors: Hu Bao Liang
Published: January 2010

According to the ways of information systems(IS) to support business strategy, this paper proposes three dimensions of IS strategy fitting for organizations in China with theoretically deductive method, and they are respectively business action support dimension, business decision support dimension and network embeddedness support dimension. Then, the paper confirms this dimensional construct based on exploratory factor analysis and confirmatory factor analysis.
The Optimization of an Authenticated Routing Protocol for Ad Hoc Networks
Authors: Lu Cheng Dong , Li Qin Wei
Published: January 2010

This paper introduced security threaten and familiar vulnerability in Ad Hoc networks, described security requirements for Ad Hoc routing, and for the most important, it improved an authenticated routing protocol. In this protocol, its routing messages were signed by node’s private key, thus then successfully defeated many kinds of attacks. However, there are some limitations. This paper provides a matter to improve it with higher transmission ratio and better security.
Research and Construction of a Model for Electricity Behavior Trust Assessment Based on Sliding Window
Authors: Zhou Ning Hui , Shen Xiao Liu , Wang Cheng Qiang
Published: January 2010

With the expanding of economic development and social demand of electricity, the issue of electricity behavior trust becomes into one of the bottleneck of the power supply enterprise on cutting down line loss and increasing profits. Traditional electricity behavior management level has certain limitations, therefore it have been established a hierarchy evaluation model for electricity behavior trust in each month and a assessment model based on sliding window for long-term electricity behavior trust. Considering the history and recent records, assisting managers not only grasp the current state of the customer's consumption behavior but also master the long-term development trends of behavior trust and improving the management level for the ultimate goal to increase the corporate profits from conserving energy and lowering line loss.
Algorithm of Call Auction Price
Authors: Sun You Fa , Liang Xiao Xiao , Guo Xu Chong , Liu Cai Yan
Published: January 2010

Algorithm of call auction price is designed according to the determining principles popular in international stock markets. Basing on the algorithm, the roots of good characteristics of call auction are oriented in these principles. Theoretical analysis shows that: 1) by implementing principles of maximum volume, minimum residual, market pressures and reference prices, the candidate transaction price set of call auction is gradually narrowing, which indicates that the algorithm has good convergence; 2) principle of reference prices guarantees the uniqueness of final transaction price; 3) principles of minimum residual and market pressures contribute to reducing price volatility; 4) principles of market pressures and reference prices help to enhance the quality of price discovery.
A Trust Model Based on Evidence Theory for P2P Systems
Authors: Huang Li Dong , Xue Gang , He Xiang Lin , Zhuang Hong Lin
Published: January 2010

Trust relationship between peers must to be established in P2P systems. But current trust models have some flaw in computing peer’s trust value, trust security and so on. This paper referred to the interpersonal social network, in which trust relationship between individuals are set up upon recommendations of other individuals, and proposed a recommendation trust model based on D-S evidence theory for P2P systems. The model deduces a peer’s local trust values from its transaction history, and then combines the peer’s local trust values by D-S combination rule and gets its global trust value finally. The experiment shows that, compared to the current trust model, the proposed model is more robust in security and more accurate in computing peer’s global trust value.
Research on Area-Feature-Based Filter Algorithm for Vehicle Recognition System
Authors: Wang Wei Hua , Wang Wei Qing
Published: January 2010

Feature extraction is a central processing in the automatic target recognition system, and noise filter is an important step in the feature extraction. A lot of research in noise filter has been proposed and used in image processing. In this paper, a noise filter algorithm based on area feature for vehicle recognition system is presented. Discussing the feature of vehicle for the recognition system, and the problem of the vehicle contour feature obtained from the traffic video. Analyzing the principle of the solve approach of the area-feature-based noise filter for vehicle recognition system. Implementing the program of the algorithm proposed in the following. Experiments have been conducted by many real vehicle images obtained from a real-time video produced by a monitor. The result shows that the new proposed method can remove the noise of the image signal for the vehicle recognition efficiently.
Change in Electrochemical Property of 12%Cr Ferritic Steel in 1M-KOH Solution Due to Creep
Authors: Abe Yousuke , Komazaki Shinichi , Mitsueda Toshiki , Kohno Yutaka
Published: January 2010

Electrochemical material characterization method was applied to the creep specimens of 12%Cr ferritic steel to evaluate the changes in precipitates during creep. Experimental results revealed that the peak current densities “Ip1” and “Ip2” appeared at specific potentials during anodic polarization curve measurement in 1M-KOH solution. These peak current densities corresponded to the selective dissolution of several kinds of precipitates, respectively. The Ip2, which reflected the amount of M23C6 and Laves phase, increased more siginificantly with creep than thermal aging. On the other hand, the effect of applied stress was not reflected on the change in Ip1, although it increased with thermal aging and creep as well as the Ip2.
Mn-Series Low Carbon Air Cooling Bainitic Steels Containg Niobium
Authors: Feng Chun , Bai Bing Zhe , Zheng Y.K. , Fang Hong Sheng
Published: January 2010

The effect of four different niobium(From 0-0.1%) addition on the mechanical properties of allotriomorphic ferrite (FGBA)/ granular bainite (BG) air cooling bainitic steels has been investigated in this paper.
The results show that (1) The 0.06%Nb steel acquired superior strength and toughness combination by applying 1250°C×60min solution treated, finish rolling at 850°C, and air cooling. The corresponding mechanical properties of the thick plate(30mm) is: σb>1050MPa, σ0.2>700MPa,δ5>17%,Akv>90J. (2) The addition of niobium refine the grain size of FGBA, and promoted the transformation of bainite structure. With the increase of niobium content, the refinement of ferrite grain and bainitic cluster is improved. (3) More refined M-A island is acquired by the small addition of niobium. According to M-A Analysis tools and transversal methods, with the rise of niobium content, the volume fraction of M-A island increase from 21% to 35%, and the average size of M-A island decrease from 1.1μm to 0.7um. (4)It is suggested that 0.02-0.06% niobium can improve the mechanical properties of the steel obviously. However, excess addition of Nb (0.1%) deteriorates the impact toughness obviously. (5)Under the synthetic roles of the microstructure refinement and precipitation strengthen, 60-160MPa yield strength improvement has been acquired in the low carbon air cooling bainitic steel by the small addition of niobium. (6)This steel is with low production cost since the alloying element Mn is cheap.
The Evolution of Transversal Surface Defects in the Axisymmetric Drawing of Copper Bars
Authors: de Castro Magalhães Frederico , de Melo Pertence Antonio Eustaquio , Béria Campos Haroldo , Paulino Aguilar Maria Teresa , Cetlin Paulo Roberto
Published: January 2010

Surface defects are an inevitable characteristic of the raw material employed in the drawing of copper wires. These defects may cause problems in the processing of the material, both during the drawing down to wires and in the final manufacturing of artifacts with the produced wire. The literature reports few analyses covering the importance of these initial defects, as well as concerning their evolution or eventual healing during the drawing. The present paper presents such an analysis for a 12.7 mm diameter copper bar displaying artificial defects 1mm wide and 0.3mm deep. Low angle drawing led to the almost complete healing of the defect after three drawing passes with a 10% reduction of area each. The use of a high semi-angle die led to a completely different situation, where no such defect healing was observed.
Kinetics of Recrystallization and Grain Growth of Cold Rolled TWIP Steel
Authors: de las Cuevas F. , Reis Mónica , Ferraiuolo A. , Pratolongo G. , Karjalainen L. Pentti , García Navas V. , Gil Sevillano J.
Published: January 2010

Hot rolled, laboratory-cast, TWIP steel samples (5.4 mm thick) of 22% Mn - 0.6% C (in mass-%) were cold rolled to different reductions (from 40 % to 70 %) and subsequently isothermally annealed for various times at temperatures ranging from 450º C to 1100º C. The evolution of recrystallization and grain growth was followed by control of the softening kinetics complemented by metallographic, OIM and microtexture observations. A map of the recovery, recrystallization and grain growth in the temperature-time space was obtained. In all instances, the grain size at the end of recrystallization was very fine, D ≤ 2 µm and larger grain sizes were the result of grain growth. A range of grain sizes 2 µm ≤ D ≤ 50 µm was covered by the grain growth experiments. A phenomenological grain growth equation that is useful for the annealing control of this steel was derived from the measurements.
Grain Growth Simulation Using Cellular Automata
Authors: Almohaisen Fahad M. , Abbod Maysam F.
Published: January 2010

It is well known that controlling the microstructure of most industrial materials is the key to control its mechanical and physical properties. In particular grain growth is very important phenomenon in material science. However, it is very difficult to examine the dynamic solidification microstructure evolution at high temperatures or during deformation processes. Computer simulations have been used as an effective solution for that difficulty. Cellular Automaton (CA) is one of the techniques that have been used to simulate the evolution of grain growth. In this study 2D grain growth simulations of Al-1%Mg alloy was simulated using CA model based on different transition principles. The first is based on low energy principle. In this method the changes of boundary energy value is compared for each cell and then choosing the one that can minimize the energy system to the largest extent. The second method is based on changes of thermal energy that is computed for each grain boundary. The transition only occurs at the highest energy value. The third method is based on starting with a number of random distributed nucleuses within the simulation area with different orientations. At each CA steps these nucleuses will grow into a grain without effecting in the other grains. The morphology and grain kinetics are studied and discussed for each case.
Optimization of the Chemical Composition and Homogenization Treatment of AA7020 Aluminum Alloy
Authors: Eivani Ali Reza , Ahmed H. , Zhou Jie , Duczczyk Jurek
Published: January 2010

Four variants of AA7020 aluminum alloy having different Zr and Cr contents were investigated aiming at reaching high recrystallization resistance during and after hot deformation. Isothermal homogenization treatments were performed at temperatures of 390-550 °C for 2 to 48 hours. The uni-axial hot compression tests were conducted at 450 °C and strain rate of 10 s-1 at a strain of 0.6. Thereafter, the samples were annealed at 550 °C for 10 min. It was found that the samples with the highest Zr and Cr contents showed the lowest volume fraction of recrystallized grains which was attributed to the highest volume fraction of Zr- and Cr-containing dispersoids formed during homogenization. The optimum homogenization treatment to achieve highest recrystallization resistance for these samples was 470 °C for 24 hours.
On Residual Stresses Development during Nitriding of Steel: Thermochemical and Time Dependence
Authors: Jegou Sebastien , Kubler Regis , Barrallier Laurent
Published: January 2010

This work deals with the development of residual stresses during nitriding of steels. The
main features of a chemico-thermo-echanical model of nitriding are presented. A micro-macroapproach is applied based on volume change computation in agreements with thermochemical modifications. Results are correlated with the characterization of a ternary Fe-C-3w.%Cr alloy nitrided at 550°C for various time. Residual stress-depth analyses are carried out by X-rays diffraction. Residual stress generation is deeply dependant on chemical and thermodynamical
evolutions during the treatment, taking advantage on microstructural effects.
Numerical Simulation of Residual Thermal Stresses in AA7050 Alloy during DC-Casting Using ALSIM5
Authors: Lalpoor Mehdi , Eskin Dmitry G. , Katgerman Laurens
Published: January 2010

Non-homogenous cooling rates and solidification conditions during DC-casting of high strength aluminum alloys result in the formation and accumulation of residual thermal stresses with different signs and magnitudes in different locations of the billet. Rapid propagation of micro-cracks in the presence of thermal stresses can lead to catastrophic failure in the solid state, which is called cold cracking. Numerical models can simulate the thermomechanical behavior of an ingot during casting and after solidification and reveal the critical cooling conditions that result in catastrophic failure, provided that the constitutive parameters of the material represent genuine as-cast properties. Simulation of residual thermal stresses of an AA7050 alloy during DC-casting by means of ALSIM5 showed that in the steady-state conditions large compressive stresses formed near the surface of the billet in the circumferential direction. Stresses changed sign on moving towards the centre of the billet and became tensile with high magnitudes in radial and transverse directions, which made the alloy prone to hot and cold cracking.
Evolution of Surface Morphology in Ni(γ)/Ni3Al(γ´) Two-Phase Foil during Electrochemical Etching
Authors: Lee Hye Youn , Demura Masahiko , Xu Y. , Wee Dang Moon , Hirano Toshiyuki
Published: January 2010

Evolution of surface morphology in Ni(γ)/Ni3Al(γ´) two-phase foil of binary Ni-18 at.%Al was examined during the electrochemically selective etching in the electrolyte of distilled water including 1 wt.% (NH4)2SO4 and 1 wt.% citric acid. In the early stage (0.5 h), only the γ matrix was etched and the outmost γ´ particles were protected by a preexisting surface product. As the γ matrix was etched more, the side surfaces of the outmost γ´ particles and the γ´ particles that were located inside were exposed in the electrolyte. They were dissolved, and had a high density of fine dimples. However, the dissolution rate of the γ´ particles was slower than that of the γ matrix and thus the selective etching was retained in this stage. Finally, at 5h, more γ´ particles were exposed and the flat and smooth surfaces of the outmost γ´ particles were completely eliminated by the dissolution on the side surfaces. From these observations plus the saturation of the current density observed in the electrochemical test, we concluded that the change in the surface morphology was finished at this stage. Thus, the surface became more rough and irregular, which resulted from the original two-phase microstructure and the fine dimple structure by transpassivation.
Quench Sensitivity and its Effect on the Microstructure and Mechanical Properties of an Al-Zn-Mg-Cu Aluminum Alloy
Authors: Liang Ze Qin , Zhang Da Tong , Qiu Cheng , Zhang Wen , Li Yuan Yuan
Published: January 2010

The high mechanical properties in 7xxx aluminum alloy are obtained by controlling the precipitation hardening microstructure. In this work, the relationship between the microstructures and mechanical properties of 7A04 (Al-Zn-Mg-Cu) aluminum alloy during isothermal aging at 140 oC after different quenching rates has been studied in order to find its useful hardening conditions. The as-extruded samples were solution heat treated at 480 oC and cooled in air, 70 oC water, 40 oC water and 0 oC ice water. Tensile test were performed and the ultimate tensile strength and percentage of elongation were obtained. The difference in the amount of precipitates is known by DSC and the morphology of the precipitates is characterized by TEM. The results indicate that the artificial age hardening response is strongly dependent on the quenching rate. Lower quenching rate results in lower tensile strength but higher percentage of elongation in the peak age condition, and this corresponds to the difference in the size and number density of the precipitates. It is concluded that the highest ultimate tensile strength is obtained in the fastest quenching rate in 0 oC ice water (up to 870Ks-1) while stable and high percentage of elongation is achieved in the intermediate quenching rate (about 226 Ks-1).
Unusual Microstructural Development upon Gaseous Nitriding of Fe-4.65at% Al Alloy
Authors: Meka S. , Schacherl R.E. , Bischoff E. , Mittemeijer Eric Jan
Published: January 2010

Employing NH3/H2 gas mixtures, Fe-4.65at% Al alloy specimens were nitrided to assess how the presence of Al, originally dissolved in the ferrite matrix, influences the development of γ-Fe4N1-x phase in the surface adjacent region. The nitrided specimens were characterized by light microscopy, X-ray diffraction, Electron Backscatter Diffraction and Electron Probe Micro Analysis. Surprisingly, formation of ε-Fe2N1-x was observed, although, for the applied nitriding parameters (nitriding potential and temperature), only the formation of γ-Fe4N1-x would be expected in case of nitriding pure ferrite. An unusual plate-type morphology of γ-Fe4N1-x was observed, contrasting with the usual continuous layer-type growth observed upon nitriding iron, Fe-Cr and Fe-V alloys. These unexpected phenomena may be explained as consequences of the need to realize a very high nitrogen supersaturation in the ferrite matrix in order to initiate the precipitation of AlN.
Changes in Microstructure of Biomedical Co-Cr-Mo-C Alloys with Solution Treating and Aging
Authors: Mineta S. , Namba Shigenobu , Yoneda Takashi , Ueda Kyosuke , Narushima Takayuki
Published: January 2010

Microstructural changes occurring in biomedical Co-Cr-Mo alloys with three carbon levels due to solution treatment and aging were investigated. Ingots of Co-Cr-Mo alloys with three different carbon levels were prepared by vacuum furnace melting; their chemical composition was Co-28Cr-6Mo-xC (x = 0.12, 0.25 and 0.35 mass%). Precipitates were electrolytically extracted from as-cast and heat-treated alloys. An M23C6 type carbide and a phase were detected as precipitates in as-cast Co-28Cr-6Mo-0.12C alloy, and an M23C6 type carbide and an  phase (M6C-M12C type carbide) were detected in as-cast Co-28Cr-6Mo-0.25C and Co-28Cr-6Mo-0.35C alloys. Only the M23C6 type carbide was detected during solution treatment. Complete precipitate dissolution occurred in all the three alloys after solution treatment. The holding time required for complete precipitate dissolution increased with increasing carbon content and decreasing solution treatment temperature. Complete precipitate dissolution occurred in the Co-Cr-Mo-C alloys solution treated at 1523 K for 43.2 ks; they were then subjected to aging from 873 to 1473 K for a heating time up to 44.1 ks after complete precipitate dissolution in solution treatment at 1523 K for 43.2 ks. The M23C6 type carbide with a grain size of 0.1–3 m was observed after aging. A time-temperature-precipitation diagram of the M23C6 type carbide formed in the Co-28Cr-6Mo-0.25C alloy was plotted.
Application of Image Plate to X-Ray Stress Measurement of Surface Thin Layer
Authors: Sasaki Toshihiko , Miyazawa Yohei , Yoshida Masanari , Fukuda Kazuto
Published: January 2010

In this study, the authors made an experiment to observe the residual stress state in the surface of the engineered parts (for example, shot-peened steel) by X-ray stress measurement. An evaluation method was proposed for the stress gradient from the information on the X-ray Debye ring obtained with an area detector. The method utilized the fact that the X-ray penetration depth is a function of the central angle of the Debye ring α. It varies due to a section of Debye ring. It also depends on the incidence angle of X-rays and the wavelength used. Mean stress over the whole penetration depths of X-rays, which is defined as the Laplace stress, was measured by the cosα method[1, 2] by using this characteristic, and the real space stress[3-5] gradient was evaluated.
Effect of Intense Plastic Straining and Subsequent Heat Treatment on Mechanical Properties of an Al-Li-Mg-Sc-Zr Alloy
Authors: Mogucheva Anna , Kaibyshev Rustam
Published: January 2010

An Al-5.1%Mg-2.1%Li-0.17%Sc-0.08%Zr (in mass%) alloy designated as 1421 Al was subjected to equal channel angular extrusion (ECAE) with rectangular shape of channels up to fixed true strains of ~4 and ~8 at a temperature of 325oC. This processing provided the formation of uniform recrystallized structures with micron scale average grain size. The 1421 Al after ECAE processing and in initial hot extruded condition was subjected to solution treatment followed by oil quenching and subsequent ageing. Fine grained structure evolved under ECAE remains essentially unchanged under solution treatment. However, this structure affects significantly the precipitation sequence during ageing. Relationships between microstructure and service mechanical properties are considered.
High-Strain-Rate Shear Testing Applied to Ti-6Al-4V
Authors: Peirs Jan , Verleysen Patricia , Degrieck Joris
Published: January 2010

In this contribution, two experimental techniques to study the dynamic shear behaviour of metals are presented and applied to Ti-6Al-4V. For bulk materials hat-shaped specimens are subjected to a high-strain-rate load in a split Hopkinson compression bar set-up. For sheet materials a purpose-developed, novel shear specimen geometry, is loaded in a Hopkinson tensile bar set-up. The value of both techniques to assess the dynamic material behaviour is discussed. The experiments are optimized by means of numerical simulations. Digital image correlation is used to extract the specimen deformation from high speed camera recordings. It is shown that the dynamic behaviour, including fracture of Ti-6Al-4V differs considerably from the static behaviour. Both experimental techniques gain complementary information.
Prediction of Mechanical Properties of Ti-6Al-4V Using Neural Network
Authors: Detak Yan Pratama , Syarif Junaidi , Ramli R.
Published: January 2010

Objective of this study is to develop simulation for predicting mechanical properties of Ti-6Al-4V alloy. Rockwell Hardness (HRC), Ultimate tensile strength (UTS) and elongation (ε) are predicted by using Neural Network (NN) with multilayer feedforward architecture. The input of simulations are chemical compositions of Ti-alloy at room temperature. The data of the mechanical properties which are reported by other researchers are used for the NN training and Gradient Descent (GD) and Lavenberg Marquardt (LM) are applied as methods of learning algorithms. The results of training by both methods are compared in order to obtain high performance of output criteria which are determined by a Normalized Root Mean Square Error (NRMSE). is used to determine the performance of output criteria. In training, the NRMSE output calculated by GD algorithm show that HRC, UTS and ε are 0.024, 0.0717 and 0.1375 respectively, while LM algorithm for HRC, UTS and ε are 0.0207, 0.0689 and 0.1150, respectively. The NRMSE predicted output of GD algorithm for HRC, UTS, and ε are 0.0658, 0.0338 and 0.2994, while LM algorithm for HRC, UTS and ε are 0.0371, 0.1192 and 0.5487 respectively. In training, values of NRMSE calculated by LM algorithm is smaller than GD algorithm. These results suggest that LM algorithm shows excellent ability for training, however the GD method is more appropriate for the training algorithm in order to obtain a high performance of output criteria. It can be concluded that the NN can be applied for predicting mechanical properties of Ti-6Al-4V alloys.
3D Observation and Image-Based Finite Element Analyses of Fatigue Crack Propagation in an Al-Mg-Si Alloy
Authors: Qu Peng Chang , Toda Hiroyuki , Zhang Hui , Qian L. , Sakaguchi M. , Kobayashi Masakazu , Uesugi Kentaro
Published: January 2010

3D fatigue crack opening and propagation behaviors in an Al-Mg-Si alloy have been investigated in this study. A combined methodology of an in-situ 3D crack visualization via the synchrotron X-ray CT and image-based numerical simulation which takes into account real crack morphology has been applied for the study. The details of a crack with non-planar torturous crack morphology have been observed and many essential features of the crack and its opening/propagation inside the material have been identified. Typical example would be the complex deformation behaviors in the region where two crack segments lying on different horizontal planes overlap each other, and the influence of complicated crack front line on local crack driving forces. We recognized that two overlapping crack segments affected significantly the local crack driving force ΔkI each other, and large mode III displacement occurred near the edge of overlapping region. The region next to overlapping was influenced to a relatively large extent through shielding the near-tip stress/strain fields thereby reducing the local crack driving forces. We also found that the sharp extrusion on crack front line had no significant influence on neighboring cracks. The combined methodology of the in-situ 3D crack visualization and the image-based numerical simulation has been demonstrated to be powerful and feasible in revealing and understanding various fracture phenomena inside materials
A Study on Similar and Dissimilar Linear Friction Welds of 2024 Al Alloy and 2124Al/SiCP Composite
Authors: Ceschini Lorella , Morri Alessandro , Rotundo Fabio , Jun Tea Sung , Korsunsky Alexander M.
Published: January 2010

The aim of the present work is to evaluate the possibility of using the Linear Friction Welding (LFW) technique to produce similar and dissimilar joints between a 2024 Al alloy and a 2124Al/25vol.%SiCP composite. In this solid state joining process the bonding of two flat edged components is achieved through frictional heating induced by their relative reciprocating motion, under an axial compressive force. Microstructural characterization of the welds was carried out by optical and scanning electron microscopy, to investigate the effect of LFW both on the aluminium alloy matrix and the reinforcement particles. The mechanical behaviour of the welded specimens was studied by means of hardness and tensile tests. The mechanisms of failure were investigated by SEM analyses of the fracture surfaces. LFW joints in MMCs resulted substantially defect free, with a uniform particle distribution, while a partial lack of bonding at the corners was observed in the others welds. The hardness decreased by approximately 10% in the welded zone, with some data fluctuations due to the complex microstructural modifications introduced by the LFW process. The joint efficiency, evaluated in respect to the UTS, was 90% for the Al alloy joints and 80% for the MMC joints. A decrease in the elongation to failure was measured in all the LFW specimens, probably related to the orientation of the plastic flow in the TMAZ, where the fracture generally occurred.
Deposition of Functional Polymer Thin Films Using Atmospheric Pressure Plasma for Biomedical Applications – Endothelialization of Vascular Prostheses
Authors: Sarra-Bournet Christian , Vallières Karine , Gherardi Nicolas , Turgeon Stephane , Massines Francoise , Laroche Gaetan
Published: January 2010

Functionalized plasma polymer thin films were obtained in a dielectric barrier discharge at atmospheric pressure in an atmosphere of N2 and C2H4. The coatings were hydrophilic, adherent, chemically stable and presented a surface concentration of NH2 suitable for further biomolecule conjugation. Covalent grafting of a linking arm (glutaric anhydride) and subsequent conjugation of fibronectin, a protein of the extracellular matrix, were successful. Finally, endothelial cell adhesion experiments were performed directly on the functionalized thin films as well as on the conjugated coatings. Effects on cell adhesion were observed as a function of the plasma thin film deposition parameters.
Physical Based Microstructure Modelling Coupled with Nucleation Theory during and after Hot Forming of AA5083
Authors: Sherstnev Pavel , Sommitsch Christof , Mitsche Stefan , Melzer Carsten
Published: January 2010

A physical model based on three types of dislocations and three nucleation sites for recrystallized grain is applied to hot rolling simulation. This model was implemented into a commercial Finite Element (FE) analysis package FORGE 2008 to calculate both the structure evolution during and the recrystallized volume fraction after hot working of aluminium alloy 5083. It is shown that the main nucleation mechanisms in the aluminium alloy are the particle stimulated nucleation (PSN) and nucleation at grain boundaries. Hence the precipitation kinetics during homogenisation was investigated by use of the thermodynamic calculation software MatCalc. To validate the simulation results hot rolling experiments were performed by means of a laboratory mill. The grain structure evolution was analysed by electron backscatter diffraction (EBSD).
Measurement of Micro Residual Stresses Near the Grain Boundary in Copper Bicrystal
Authors: Shiro Ayumi , Takao Hanabusa , Okada Tatsuya , Masayuki Nishida , Kusaka Kazuya , Sakata Osamu
Published: January 2010

Residual stresses near the grain boundary of a bicrystal were measured by synchrotron radiation of SPring-8 at Japan Synchrotron Radiation Research Institute. A copper bicrystal specimen with a 90-degree tilt boundary was deformed 30% in tension. After the plastic extension, kink bands developed in a deformed matrix along the grain boundary. In this study, we focused on the residual stresses in the deformed matrix and the kink band. Residual stresses were evaluated by the X-ray single crystal measurement method. Stereographic projections were used to determine crystal orientations of deformed regions. Our observation showed that crystal orientations were different between the deformed matrix and the kink band. Residual stresses in the direction along the grain boundary in the deformed matrix and kink band were compressive. Residual stresses in the direction vertical to the grain boundary were seen opposite between the deformed matrix and the kink band.
Influence of Second-Phase Particles on Microstructure Evolution and Mechanical Behavior of Ultrafine Grained Al-Alloys Produced by Severe Plastic Deformation
Authors: Hu Wei Ping , Berghammer Rolf , Liu Zhen Shan , Mu Si Jia , Gottstein Günter
Published: January 2010

In present investigation the influence of second phase particles on microstructure evolution during confined channel-die pressing (CCDP) and mechanical behaviour after CCDP were studied using two-phase Al alloys of Al-1.5Mn and Al-5Zn-1.6Mg. The investigation results revealed different grain refinement kinetics during CCDP and distinct mechanical behaviours after CCDP for both alloys. The results are discussed based on the influence of the second phase particles on dynamic recovery and the interaction with mobile dislocations during plastic deformation.
Finding the Optimum Cutting Conditions for Face Milling 13% Manganese Steel Using the Taguchi Design Method and Predictive Equations
Authors: Speedie James A. , Black Ian , Ritchie James M.
Published: January 2010

In this paper, a methodology for determining the optimum machining parameters for a face mill operation is presented. Taguchi design of experiments was used in company with orthogonal arrays in order to study the effects and interactions that selected parameters had on the cutting behaviour. The parameters that were included in the study were cutting speed, feed rate, depth of cut and the effects of cutting fluid. Using the orthogonal array experimental runs were set up and carried out on specimens of metal plate on a CNC milling centre. The studied material was 13% Austenitic Manganese Steel. The response factors for the experimental runs were surface finish, spindle load, material removal rate, cutting forces and surface hardness. From the results and using the orthogonal arrays a set of empirical models were derived for each response factor which could be used to predict the optimal controllable factor settings for a given production criteria.
Synchrotron µCT Investigation of the Collapsing Pore-Network of Gelatin Scaffolds under Compression
Authors: Thiem Annette , Lum Victoria , Grupp Rainer , Riesemeier Heinrich , Bordia Rajendra , Schubert Helmut , Zehbe Rolf
Published: January 2010

Biomaterials based tissue engineering requires optimization of several parameters. The most important parameters can be attributed to biocompatibility, degradational behaviour, mechanical stability and structural design. In previous studies we have established a porous gelatine based scaffold material, with parallel oriented pore channels. Although, tomographic data has been derived on dried scaffold samples, it remains unclear how the pore channel network interacts under load in a wet environment. We developed an experimental setup to compress biomaterials in a wet environment during exposure to synchrotron generated X-rays using a micrometer screw with a force sensor. Achieving good X-ray absorption contrast in polymeric biomaterials immersed in water is rather difficult, as water absorption prevents detailed imaging. Phase contrast imaging on the other hand allows for improved imaging results due to the attenuation of phase boundaries in the imaged data, neglecting effects of X-ray absorption in the watery phase nearly completely. Best results were obtained for X-ray energies of 30 keV with a scintillator to sample distance of 1090 mm with the established experimental setup. Due to over attenuation of phase boundaries at higher beam energies, this energy was finally chosen. As a result, we could evaluate the collapsing pore network upon loading with the possibility to enhance the structural design for future studies.
Development of a Plasma Process for Microfluidic Devices in the Prospect of Cell Attachment
Authors: Vo Tan Tho Nathalie , Willaime Hervé , Tabeling Patrick , Arefi-Khonsari Farzaneh , Mantovani Diego , Tatoulian Michael
Published: January 2010

Plasma processing has been developed to produce selective chemistry in the inner surface of a microfluidic system. This dry process is an alternative solution to the Chemical Vapor Deposition (CVD) process that allows us to work at low temperatures thus avoiding the degradation of the substrate by heat. The present study focused on the surface modification of PDMS in order to make them more hydrophilic and capable to exhibit a high percentage of COOH functions which will provide a good asset for future cell attachment.
Existence of Local Network Structure in Binary Amorphous Metals and its Contribution to Elastic Properties
Authors: Wakeda Masato , Shibutani Yoji
Published: January 2010

The paper focuses on the characteristic local network structure of icosahedra observed in the relaxed amorphous metals and its contribution to their elastic properties. Using molecular dynamics method, CuxZr100-x binary amorphous models are constructed by rapidly quenching process from liquid. Voronoi polyhedron analyses expose the existence of the medium-range local network structure composed of inter-penetrating icosahedra. It is found that the globally averaged shear modulus obtained from the atomistically defined elastic moduli decreases with increasing free volume content in the condensed matter. The contribution of the densely packed icosahedral cluster with higher elastic rigidity to the global elastic modulus is discussed.