bluuebunny/crossref_metadata_2025 huggingface dataset:
‘It’s Almost like Talking to a Person’
Authors: Savin-Baden Maggi , Tombs Gemma , Burden David , Wood Clare
Published: July 2013

This paper presents findings of a pilot study which used pedagogical agents to examine disclosure in educational settings. The study used responsive evaluation to explore how use of pedagogical agents might affect students’ truthfulness and disclosure by asking them to respond to a lifestyle choices survey delivered by a web-based pedagogical agent. Findings indicate that emotional connection with pedagogical agents was intrinsic to the user’s sense of trust and therefore likely to affect levels of truthfulness and engagement. The implications of this study are that truthfulness, personalisation and emotional engagement are all vital components in using pedagogical agents to enhance online learning.
The Role of Complementary Resources in the Development of E-Supply Chains and the Firm’s Performance
Authors: Lee Yoo-Taek , Ryu Sung-Yong , McKone-Sweet Kathleen E.
Published: July 2013

E-supply chains (e-SCs), which are Internet-enabled supply chains, are progressively being implemented by companies to improve their operational and financial performance. Several studies exist where the association between the development of an e-supply chain and the performance of a firm have been investigated. However, there is a paucity of literature that describes how information technology (IT) resources interact with other complementary resources to e-supply chains that positively impact a firm’s performance. This paper seeks to adopt a resource-based view of the firm (RBVF) and empirically tests a framework that identifies and validates the relationships among IT resources, complementary resources to e-supply chains, and performance of a firm. This study utilizes secondary data from two sources – data collected by the South Korean Ministry of Commerce, Industry and Energy (MOCIE) and financial data from the Korea Exchange. The data from a total of 170 firms representing 10 industries in South Korea was analyzed using a partial least-squares technique (PLS). The results of the analysis confirm that IT resources do not directly influence supply chain performance. However, when associated with a complementary resource, IT resources positively affect both supply chain operations and a firm’s financial performance. The findings of this research support the current existing literature on the RBVF approach with regard to the domain of supply chain management, and can provide additional insights to industry practitioners on how to effectively utilize complementary resources in developing e-SCs to deliver improved performance.
Applying Bayesian Network Techniques to Prioritize Lean Six Sigma Efforts
Authors: Li Yanzhen , Sawhne Rapinder S. , Wilck Joseph H.
Published: July 2013

In order to retain competitive advantages, many manufacturing organizations have applied Lean Six Sigma techniques to improve production processes. The general approach for implementing Lean Six Sigma is to perform various projects to tackle specific problems or areas. However, with the manufacturing system and its external environment becoming more and more complex, it is simply not possible to solve all the problems given the limited resources. The purpose of this study is to develop a model that provides a systematic evaluation for potential opportunities to enhance the effectiveness of Lean Six Sigma. Deriving from the Bayesian Network methodology, the proposed model combines a graphical approach to represent cause-and-effect relationships between events of interests and probabilistic inference to estimate their likelihoods in the area of process improvement. The developed model can be used for assessing the problems associated with Lean Six Sigma initiatives and prioritizing efforts to solve these problems.
Managing Architectural Reconfiguration at Runtime
Authors: Loukil Sihem , Kallel Slim , Jmaiel Mohamed
Published: July 2013

Managing dynamic reconfiguration of software systems is a tedious task in the software development because of the substantially increasing need for continuously available systems even at runtime. In particular, the software architecture of dynamically adaptive systems must continuously adapt to varying environmental conditions and user requirements. Therefore, they propose a wide range of possible configurations. The static enumeration of all the possible configurations is a difficult task. Moreover, not all dynamic reconfiguration operations can be foreseen at design time. Some reconfigurations may appear when the system is already deployed. In this context, we propose to combine the Architecture Description Languages and the Aspect-Oriented Software Development paradigm in order to make the dynamic reconfiguration process easier to design, understand and possible to validate. Also, this combination allows to easily evolving the reconfiguration policies even at runtime.
Methodology for Learning of the Surface Finish Evaluation through the Generation of Theoretical Roughness Profiles
Authors: Miguel V. , Manjabacas M. Carmen
Published: July 2013

In the present work a methodology about the learning-teaching process based on the generation of surface finish theoretical profiles is presented. These profiles should be evaluated analytically in an easy way. The generation of these profiles is done numerically, so that, they can be also analyzed through specific roughness software applications. Taking into account the latter point, it is possible to work with all the possibilities that the software allows us, being able to check the operations that are carried out and, in this way, increasing the degree of comprehension about the meaning and interpretation of the calculated parameters. Therefore, the comprehension about the variables that are indicated by this software for the evaluation of the roughness profile is much easier. This method allows us to be able to establish adequate measurement and analysis protocols. Finally, a specific method related to the filtering of the profile through Fast Fourier Transform is proposed. A reference to the normalization related to the measurement of the surface finish is also established
A Wiki Collaborative Application for Teaching in Manufacturing Engineering
Authors: Cuesta E. , Sánchez-Lasheras F. , Álvarez B.J. , González-Madruga D.
Published: July 2013

The interest of the present work is focused on the improvement of the students learning process through the use of a Wiki-like platform. In our research The Wiki was intended as a mean in order to make easier the learning project. During the academic year 2011/2012 the Area of Manufacturing Engineering of the University of Oviedo was involved in a project which aim was the creation of a Wiki. Nowadays this software is used as auxiliary material for other subjects that are given by the Manufacturing Engineering Area in those new Engineering degrees that have been created in order to adapt the studies to the requirement of the European Higher Education Area (EHEA). According to the results obtained by the students, it can be stated that the higher the mark of the students Wiki the better his/her mark in the exam is.
Experimental Introduction to Surface Roughness Parameters Measurement
Authors: Teixidor Daniel , Quintana Guillem , de Ciurana Joaquim
Published: July 2013

Surface roughness influences the performance of a finished part. In machining operations, the surface roughness generated is influenced by an enormous set of factors. In ball end milling operations, the geometric characteristics of the cut clearly affect the surface crests generated. This paper presents an experimental methodology that permits engineering students to identify and analyze the surface roughness. The methodology is applicable to training courses and surface texture generation as well.
Pre-Reduction of Chromite by Thermogravimetric (TG) Analysis
Authors: Khan D.M.A.
Published: July 2013

Thermogravimetric experiments on prereduction of single pellet and multiple pellets were conducted in Muffle furnace at 1500oC. Reduction smelting of Chromite in Fe-C melt in TG setup indicates CR is reduced faster than CG and CB. The reduction mechanism takes the path of first order reaction kinetics. Only 50% Cr metallization could be obtained at 1550oC from the reduction smelting experiments.
Fabrication of Nanorod Array Structure by Using Aluminizing and Internal Oxidation of Ni with Micro-Channels
Authors: Ishizaki Takeshi , Do Dung Thi Mai , Nanko Makoto
Published: July 2013

A metallurgical method for preparing oxide nano-rod array structure was developed with internal oxidation of Ni(Al) solid solution obtained by aluminizing Ni with a pack cementation technique. The present method was applied in order to fabricate nano-rod array on the micro-channel surface of microreactor. A micro-channel with 1 mm in depth, 1mm in width and 10 mm in length was fabricated on the Ni disk by an electric discharge machining and electropolishing. The Ni disk with a micro-channel was annealed at 1300°C for 12 h in vacuum. The sample was aluminized by a pack cementation using pack powder mixture consisting of 10 mass% of Ni3Al, 88 mass% of Al2O3 and 2 mass% of NaCl at 1100°C for 12 h in a flow of argon gas. The sample was oxidized from 1000 to 1200°C for 6 h with the Co/CoO buffer. Ni matrix in internally oxidized zone was removed by electropolishing to expose nano-rods. Al2O3 nano-rod array located on the micro-channel surface was successfully fabricated with the proposed technique. Diameter and height of nano-rods were ranged from 100 to 300 nm and from 1.5 to 3 µm, respectively.
Synthesis of Palladium Nanoparticles in Various Carbon Materials
Authors: Bae Min A , Baek Jae Ho , Lee Man Sig
Published: July 2013

The outstanding properties of Pd-base catalysts make is attractive for applications in various field, such as hydrogen storage, catalysis, fuel cell, chemical sensing and so forth. Therefore, research studies have been carried out on its preparation and characterization. Commonly, the Pd must be deposited on support materials with a large surface area to provide high metal dispersion and a high electrical conductivity to facilitate electron transfer, which carbon materials. The purpose of this study is to investigate not only synthesis of various carbon materials(graphene, carbon nanotube(CNT), active carbon, carbon black) supported Pd but also the confirmation of the properties. The characterization of Pd catalysts composites was performed by X-ray diffra ction(XRD), Brunauer-Emmett-Teller(BET), scanning electron microscopy (SEM) and transmission electron microscopy(TEM). According to TEM image, Pd nanoparticles were highly dispersed on surface of graphene
Compressive Properties of Porous Aluminum Alloy Fabricated by Joining Pipes and Melt through Continuous Casting
Authors: Ichikawa Junichi , Hayashida Tatsuro , Suzuki Shinsuke
Published: July 2013

A porous aluminum alloy was fabricated by joining pure aluminum pipes and Al-13mass% Si melt through continuous casting. Compressive tests were carried out with test specimens of the porous aluminum alloy fabricated by this method, non-porous aluminum alloy fabricated by continuous casting using Al-Si melt, and porous aluminum alloy consisting of only Al-Si fabricated by drilling non-porous Al-Si bar. From the compressive tests, it was confirmed that specific proof strength of the porous aluminum alloy fabricated by joining pipes and melt can be described by rule of mixture of Al-Si base metal, pure aluminium pipes and pores.
Synthesis of Polyglycerol Fatty Acid Ester for Insulating Oil
Authors: Gwon Mi Seong , Ryu Young Bok , Park Dae Won , Lee Man Sig
Published: July 2013

Offshore wind power is eco-friendly new regeneration energy producing electricity using a strong wind of the sea. Offshore wind power consists of pitch controller, nacelle, blade and transformer. Insulating oil for transformer needed to low pour point, high flash point and biodegradable considering the low temperature of the sea and environmental pollution. In this study, polyglycerol fatty acid ester was prepared polyglycerol and fatty acid using various catalysts for insulating oils. We investigated the effect of catalysts on the yield of polyglycerol fatty acid ester. In addition, we were measured the pour point and flash point of the prepared polyglycerol fatty acid ester.
A Model for Stress History during Sintering of Ceramic Laminates
Authors: Yasuda Kouichi , Lv Pei Ling
Published: July 2013

This paper proposes a model for estimating stress history during sintering of ceramic laminates. A symmetrical 3-layered laminate is assumed, and one-dimensional elastic calculation gives the stress change of each layer during heating, keeping at the sintering temperature, and cooling, respectively. How to get the stress history is actually shown by incorporating data of mechanical and thermal expansion properties of calcined monolayers. The validity of this model is discussed with a preliminary experiment on dense alumina / porous alumina laminates.
Effects of CNT Addition on Mechanical Properties, Electric Conductivity and Oxidation Resistance of Al2O3-TiC Composite
Authors: Sano Hideaki , Morisaki Junichi , Zheng Guo Bin , Uchiyama Yasuo
Published: July 2013

Effects of carbon nanotubes (CNT) addition on mechanical properties, electric conductivity and oxidation resistance of CNT/Al2O3-TiC composite were investigated. It was found that flexural strength, Young’s modulus and fracture toughness of the composites were improved by addition of more than 2 vol%-CNT. In the composites with more than 3 vol%-CNT, the oxidation resistance of the composite was degraded. In comparison with Al2O3-26vol%TiC sample as TiC particle-percolated sample, the Al2O3-12vol%TiC-3vol%CNT sample, which is not TiC particle-percolated sample, shows almost the same mechanical properties and electric conductivity, and also shows thinner oxidized region after oxidation at 1200°C due to less TiC in the composite.
Dynamic Transformation during Simulated Hot Rolling
Authors: Jonas John J. , Ghosh Chiradeep , Basabe Vladimir V.
Published: July 2013

High temperature flow curves were evaluated on two Nb steels in both compression and torsion and at a series of temperatures and strain rates. The critical strains for the initiation of dynamic transformation (DT) were determined by the double differentiation method. These are shown to be distinctly lower than those associated with dynamic recrystallization (DRX). It is also evident that the compression critical strains for both DT and DRX are lower than the equivalent torsion critical strains. Mean flow stresses (MFSs) were calculated by integration from the flow curves. When plotted against inverse temperature, stress drops were observed about 30 degrees above the Ae3. These drops are shown to be caused by the dynamic transformation of austenite to ferrite, a softer phase. The characteristics of the ferrite produced dynamically are described and the transformation is shown to be displacive in nature, leading to the appearance fine Widmanstatten plates.
Atomic Scale Investigation of Solutes and Precipitates in High Strength Steels
Authors: Hodgson Peter , Mukherjee Subrata , Beladi Hossein , Xiong Xiang Yuan , Timokhina Ilana B.
Published: July 2013

Two steels, ferritic, high strength with interphase precipitation and nanobainitic, were used to show the advances in and application of atom probe. The coexistence of the nanoscale, interphase Nb-Mo-C clusters and stoichiometric MC nanoparticles was found in the high strength steel after thermomechanical processing. Moreover, the segregation of carbon at different heterogeneous sites such as grain boundary that reduces the solute element available for fine precipitation was observed.
The APT study of the solutes redistribution between the retained austenite and bainitic ferrite in the nanobainitic steel revealed: (i) the presence of two types of the retained austenite with higher and lower carbon content and (ii) segregation of carbon at the local defects such as dislocations in the bainitic ferrite during the isothermal hold.
Young's Modulus Profile in Kolsterized AISI 316L Steel
Authors: Balijepalli S.K. , Donnini Riccardo , Kaciulis S. , Montanari Roberto , Varone A.
Published: July 2013

AISI 316L steel, subjected to a low temperature carburizing treatment (kolstering), has been examined by Mechanical Spectroscopy (MS) and nanoindentation to determine the Youngs modulus of the surface hardened layer (S phase). MS results showed that the average value of elastic modulus of S phase is 202 GPa, a little higher than that of the untreated material.Nanoindentation tests, carried out with loads of 5, 15 and 30 mN, evidence a modulus profile vs depth: E is ~ 400 GPa at a distance from the surface of ~ 110 nm, then decreases to reach the value of the steel substrate (190 GPa) at 33 μm.These results, together with X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) measurements of carbon concentration profile, can be explained by considering the presence of a very thin surface layer, different from S phase and consisting of a mixed structure of Diamond-like carbon (DLC) and tetrahedral carbon (taC).Furthermore, the same experiments have been carried out also after heat treatments at 450 °C to correlate the modulus change to the decomposition of the metastable S phase leading to the formation of (Cr,Mo)C and Cr23C6carbides in a Cr-depleted austenitic matrix.
Effect of Rare Earth Addition on Dynamic Recrystallization and Precipitation Behavior of a Niobium-Containing Microalloy Steel
Authors: Wang Hai Yan , Ren Hui Ping , Yang Hui , Wang S.D. , Li D.X.
Published: July 2013

Hot compression experiments were carried out on rare earth (RE) added and RE-free Nb-containing steels by using a Gleeble simulator. Stress-strain curves obtained at various temperatures were analyzed to investigate the dynamic recovery and dynamic recrystallization softening behaviours. Morphology, size and number of precipitates in the both steels were examined by means of transmission electron microscopy (TEM). The results showed that, for the experimental Nb-containing steel, the grain size was fined by the RE addtion. In general, dynamic recrystallization cant occur in two steel under 40% deformation rates, and the deformation resistance of RE-containing steel is higher than that of RE-free steel in both the the austenite and ferrite temperatures range.While under the higher deformation rate, the dynamic recovery starting strains of the RE addition steel are higher than that of RE-free steel.It is also shown that the number of precipitate in the RE-containing steel more than that in the RE-free steel, which is due to the RE increasing nucleation rate and promoting Nb carbonitrides precipitation growth in the austenite region. Furthermore, the carbon activity may change by the RE addition, and thereby promote the precipitation strengthening of Nb-microalloyed steel.
Numerical Simulation of Thermal Stress and Deformation in a Casting Using Finite Difference Method
Authors: Xue Xiang , Wang Yue Ping , Zhang Yue Bing
Published: July 2013

A software code for simulating thermal stress in castings was developed using finite difference method (FDM). The one way coupled map model was adopted to treat the relationship between the solidification and the thermal stress in castings. A method of killing the mold element whose temperature begins to decrease was employed to deal with the mold/casting interaction. The thermal stress and deformation in a stress frame casting were experimentally studied and analyzed by this software code. The results simulated and the residual stress measured are in good agreement. This indicates that the software code is a useful tool for predicting thermal stress and deformation in castings. Therefore, it provides a scientific way to improve the casting dimensional accuracy and reduce the defects caused by thermal stress.
Numerical Simulation of Hot Rolling
Authors: Kawalla Rudolf , Schmidtchen Matthias
Published: July 2013

In the present paper actual demands for modern simulation strategies for hot rolling are discussed. The main focus of the discussion is on material flow simulation for hot rolling and the computation of material inhomogeneities. An overview on simulation techniques for material flow and microstructure evolution is given. Approaches for new simulation strategies which give fast results with a high modeling depth are discussed. As a result of actual investigations a fast model for material flow is presented.
Soft Reduction of a Cast Ingot on the Incomplete Crystallization Stage
Authors: Cherkashina Tanya I. , Mazur Igor , Aksenov Sergey A.
Published: July 2013

Numerical and physical simulation on model samples can provide data for various aspects of metal forming, without resorting to time-consuming and costly full-scale tests. This paper presents examples of modeling of the deformation of a slab with a liquid core. The use of soft reduction can enhance the homogeneity of the structure, which improves the quality of cast billets. Mathematical modeling is described here where the fluid layer is taken into account by the influence of boundary conditions in the crust in the form of ferrostatic pressure, which allows calculation of the intensity of deformation, total deformation and strain. It also provides a novel method for studying the process of soft reduction. It is based on a physical model of the slab consisting of a closed solid shell made of a calibrated lead shot and the Wood's alloy. To simulate the liquid molten metal, the interior of the shell is filled with gelatin. This approach can be applied to further studies on deformation processes and the penetration of deformation into complex metallic systems.
Evolution of Strain in Multipass Hybrid Equal Channel Angular Pressing Using 3D Finite Element Analysis
Authors: Sahai Ankit , Sharma Rahul Swarup , Raj K. Hans
Published: July 2013

Severe Plastic Deformation (SPD) is well known process for producing nanostructured material from coarse material. Present paper is an effort to integrate the two well known SPD techniques Equal Channel Angular Pressing (ECAP) and Twist Extrusion (TE) to develop a new Hybrid ECAP (HECAP) technique that can produce nanostructured material more economically. In this technique, the specimen is subjected to both ECAP and TE in the same die setup. Finite Element (FE) modeling of metal forming processes has become an important tool for designing feasible production processes, because of its unique capability to describe the complex geometry and boundary conditions. FE Modeling of the above hybrid process is attempted in FORGE. The simulation results clearly depict the change in equivalent strain in the entire specimen on account of this process upto four passes. A comparison is made between FE results of simple ECAP and HECAP upto four passes. The study indicated that equivalent strain is much higher in case of HECAP in comparison to ECAP for same friction conditions. Also, the study is extended to analyse the effect of friction, channel angle and forging force on equivalent strain using current FE model. HECAP opens new possibilities for improving equivalent strain in same number of passes as compared to ECAP. This study is expected to contribute in forming UFG materials that are useful for automobile and aerospace industries.
Simulation of Thermomechanical Control Processing of Steels through the Use of Experimental Planning and FEM
Authors: Kodzhaspirov G.E. , Rudskoy A.I.
Published: July 2013

The experimental planning method has been used for the examination of the combined effect of the temperature, strain, strain rate and time elapsed from the end of deformation to the start of quenching parameters of the Thermomechanical Control Processing on the structure and mechanical properties. Simulation of Thermomechanical Control Processing for the definite cross-section of profile by Finite Element Method on the base of the data obtained by the experimental planning method allowed to predict structure and mechanical properties and to develop computer modelling for the different cross-section of rolling profile.
Formation of an Ultrafine-Grained Austenite-Containing Microstructure from a Cold-Rolled Medium-Manganese Steel Processed Using Intercritical Annealing
Authors: Dong Han , Cao Wen Quan , Shi Jie
Published: July 2013

The behavior of 60% cold-rolled medium-manganese steel (0.1C5Mn) during intercritical annealing, has been examined using various techniques. Microstructural observations showed a slight coarsening of the subgrain/grain structure during intercritical annealing, without any apparent change in the misorientation distribution. In addition, the formation of ultrafine austenite grains took place mainly at high-angle boundaries and rarely at low angle boundaries, suggesting a heterogeneous austenite nucleation process in this steel. The results indicated that the annealing behavior of cold rolled medium manganese steels is controlled by the extensive recovery of the ferrite phase and formation of austenite phase with an austenite volume fraction of ~20%. It was proposed that the segregation of manganese and carbon to high-angle boundaries promoted austenite nucleation and growth, as such segregation decreases the Gibbs energy of austenite.
Influence of Different Interpolation Techniques on the Determination of the Critical Conditions for the Onset of Dynamic Recrystallisation
Authors: Lohmar Johannes , Bambach Markus
Published: July 2013

Accurate modeling of dynamic recrystallization (DRX) is highly important for forming processes like hot rolling and forging. To correctly predict the overall level of dynamic recrystallization reached, it is vital to determine and model the critical conditions that mark the start of DRX. For the determination of the critical conditions, a criterion has been proposed by Poliak and Jonas. It states that the onset of DRX can be detected from an inflection point in the work hardening rate as a function of flow stress. The work hardening rate is the derivative of the flow stress with respect to strain. Flow curves are in general measured at a certain sampling rate, yielding tabular stress-strain data, which are per se not continuously differentiable. In addition, inevitable jitter occurs in measured flow curves. Hence, flow curves need to be interpolated and smoothed before the work hardening rate and further derivatives necessary for evaluating the criterion by Poliak and Jonas can be computed. In this paper, the polynomial interpolation originally proposed by Poliak and Jonas is compared to a new approach based on radial basis functions using a thin plate spline kernel, which combines surface interpolation of various flow curves and smoothing in a single step. It is shown for different steel grades that the interpolation method used has a crucial influence on the resulting critical conditions for DRX, and that a simultaneous evaluation by surface interpolation might yield consistent critical conditions over a range of testing temperatures.
Hot Simulation Compression of In Situ TiBw/Ti6Al4V Composites with Novel Network Microstructure
Authors: Huang Lu Jun , Zhang Yu Zi , Geng Lin
Published: July 2013

The hot compression behavior of in situ TiB whiskers reinforced Ti6Al4V (TiBw/Ti6Al4V) composites with a novel network microstructure is investigated in the temperature range of 900-1100°C and strain rate range of 0.001-10 s-1. The results show that all the stress-strain curves of the composites display peak flow, softening and steady-state. Moreover, the peak flow stress decreases with increasing temperatures and decreasing strain rates. Processing map of the composite is constructed using the dynamic material model (DMM). Dynamic recrystallization (DRX) of α phase is observed in the deformation region corresponding with peak efficiency of the processing map. However, the flow instability region ranged from 900 to 1100°C at strain rates higher than 1.0 s-1should be avoided.
Studies on Martensite Transformation in a Metastable Austenitic Cr-Mn Stainless Steel
Authors: Kisko Anna P. , Rovatti Ludovica , Misra R.D.K. , Sahu Puspendu , Talonen Juho , Karjalainen L. Pentti
Published: July 2013

The influences of the heating rate and annealing duration on martensite formation and its reversion to austenite have been investigated in a 60% cold-rolled metastable high-manganese austenitic Type 204Cu stainless steel. A Gleeble 3800 thermomechanical simulator was used for dilatometric measurements. Cold-rolled steel pieces were either heated up to 1000 °C at various heating rates between 5 °C/s and 150 °C/s followed by quenching to room temperature, or heated and held at temperatures in the range of 450 620 °C for different durations between 0.1 600 s. In heating experiments, dilatation curves revealed an expansion of a specimen starting around 550 °C followed by contraction, both processes depending on the heating rate. These dimensional changes could be correlated to the formation and reversion of a ferromagnetic phase, α-martensite. Some martensite was also formed during isothermal holding in connection with tempering of the pre-existing α-martensite before the following reversion, as established by magnetic measurements. Tempering of martensite was revealed by microhardness behaviour, X-ray diffraction analysis and transmission electron microscopy.
Al/Al2O3 Nanocomposite Produced by ECAP
Authors: Casati Riccardo , Amadio Matteo , Biffi Carlo Alberto , Dellasega David , Tuissi Ausonio , Vedani Maurizio
Published: July 2013

Metal matrix nanocomposites have been produced by powder metallurgy route. Al and nanoAl2O3powders were grinded through high energy ball milling. Then, the composite powders were sintered by Equal Channel Angular Pressing (ECAP). 12 ECAP passes were carried out in order to improve the dispersion of the hard particles. SEM analysis was performed to investigate the distribution of the ceramic nanoparticles within the matrix. Hardness tests were executed to evaluate the mechanical behavior of the nanocomposites. Finally, mechanical strength values obtained by numerical models were compared with those estimated from hardness measurements. High energy ball milling followed by ECAP process revealed to be a suitable route for the production of metal matrix composites reinforced with well dispersed nanoparticles.
The Effects of Phosphotungstic Heteropoly Acid on Degradation Behaviour of Hardened Epoxide Polymers in Near-Critical Water
Authors: Liu Yu Yan , Jiang Li Qin , Wu Song Quan , Liu Yu Ting
Published: July 2013

This paper aims to study the catalytic effects of phosphotungstic acid on the degradation behaviour of E-51/DDM and E-51/MeTHPA epoxy resins. The results show that phosphotungstic acid promotes the decomposition of E-51/DDM and E-51/MeTHPA in different degree. The decomposition rate of E-51/MeTHPA is relatively higher. According to the GC-MS results, the composition of products when phosphotungstic acid is used as the catalyst is complicated, indicating that the decomposition mechanism is complicated.
The Effect of Stabilizers on the Grain Growth and Impact Toughness of 21%Cr Ferritic Stainless Steels High-Temperature Heat-Affected Zones
Authors: Anttila Severi , Karjalainen L. Pentti , Porter David A.
Published: July 2013

Grain growth during welding and the level of impact toughness in thermally simulated high-temperature heat-affected zones were determined for a series of AOD-level laboratory melted 21% chromium ferritic stainless steels. The effects of niobium and titanium stabilizing elements on microstructure were evaluated by optical and scanning electron microscopy.
Overall, grain growth was only slightly affected by the stabilizing element ratio. On a weight percent basis, niobium was the most effective for restricting the grain growth in the heat-affected zone either alone or in the presence of a small amount of titanium. The predominantly niobium-stabilized heats also had the highest impact toughness in both air-cooled and water-quenched conditions, differences in transition temperatures being up to 55 °C. However, all the simulated heat-affected zones fit into a narrow ductile-to-brittle transition temperature band width of 30 °C, even including variations in heat input. This was attributed to intense grain boundary precipitation, which occurred even with a low heat input.
Effect of Sn Content on the Microstructure, Mechanical and Electrical Properties of Ti2AlC/Cu Joints Brazed with Cu-Sn-Ti Filler Alloy
Authors: Zhang Jie , Wang Guo Chao , Zheng Yi
Published: July 2013

In the present study, Cu-Sn-Ti filler alloy with different content of Sn was used to join Ti2AlC ceramic and copper at 950 °C for 10 minutes. Effect of Sn content on the microstructure, mechanical property and electrical conductivity of the joints were investigated.The results indicate that the joint was comprised of five parts: copper substrate/ diffusion area in the copper substrate (Cu [Al, S solid solutions)/ brazing layer (Cu [Al, S+CuSn3Ti5)/ interaction area in the Ti2AlC substrate (Ti2AlC+ Cu [A+AlCu2Ti+TiC)/ Ti2AlC ceramic substrate.With the content of Sn element in the joint increasing, the filler alloy performed lower melting point and better fluidity during brazing. Thus partial filler alloy flowed out of the brazing seam, leading to the reduction of CuSn3Ti5 phases. Simultaneously, more Ti and Al diffused toward the Cu substrate, where a line of AlCu2Ti phases was formed. The maximum shear strength 158.5 MPa was obtained by using Cu80Sn10Ti10 (at.%) filler alloy, at which the joint strength was 71% of that of the Ti2AlC ceramic. The joint strength was deteriorated while the higher content of Sn was incorporated (>10 at.%), which was caused by the weak interfacial bonding between the substrates and the brazing layer. Besides, the electrical conductivity was decreased from 5.65×106 s/m to 4.99×106 s/m with increasing Sn content in the filler alloy.
The Possibility to Use Optical Emission Spectrometry for Identifying the Amount of Inclusions in Steels
Authors: Ruuska Jari , Ollila Seppo , Leiviskä Kauko
Published: July 2013

Optical emission spectrometry, OES, has been used widely to define the chemical element analysis. The possibility to use OES-PDA-data to identify the amount of inclusions in steel has been studied to get a quick knowledge about inclusions during the process. From the histogram of intensity levels the amount of chemical element being in steel matrix and in inclusions can be observed. The inclusions are observed to be in the tail of histogram. The setting of a correct threshold to divide the histogram into steel matrix and inclusions parts isproblematic. In this research some statistical methods and a histogram threshold method are tested for OES-PDA-data from steel samples.The research discussed in this paper has been carried out in co-operation with Ruukki Metal, at their Raahe Works in Finland. Steel samples were taken from different process stages and different process routes. The objective was to examine the amounts of inclusions at different process stages and how they differ during the process. The research was focused on the chemical elements that are most common in the inclusions. From the results it is observed that calcium and aluminium are identified pretty well, but for other elements both correct and incorrect results are obtained. This method shows a potential to identify the amount of inclusions, though further research is needed.
Eigenvalue Analysis of Roots Type Vacuum Pump Using FE-Method
Authors: Lee Jeong Hoon , Lee Jong Myeong , Ha Jeong Min , Gu Dong Sik , Choi Byeong Keun
Published: July 2013

The demand and importance of vacuum pumps are increasing, because the necessity of dry vacuum pump is proven in semiconductor industry. Various types of vacuum pumps have been developed, and in this research a roots type vacuum pump has been analyzed with a variety of mathematical analysis. Analysis of eigenvalue by FEM analysis and Modal Test were performed through the Roots type vacuum pump and using the results of irregular vibration and instability an assessment has been performed.
Physical Simulation of Hot Rolling Steel Plate and Coil Production for Pipeline Applications
Authors: Carretero Olalla Victor , Sanchez Mouriño N. , Thibaux Philippe , Kestens Leo , Petrov Roumen H.
Published: July 2013

Within the techniques and equipments used to simulate industrial thermomechanical processing of High Strength Low Alloy (HSLA) pipeline steels, hot rolling laboratory mill equipped with cooling bed and coiling simulation furnace allows, not only accurate control of strains, temperatures, inter-pass times, and cooling rates but also enough amount of processed material for micro-structural characterisation and mechanical testing. Despite some differences with the industrial rolling, laboratory rolling offers a better simulation of the industrial rolling conditions than other thermo-mechanical simulators in terms of deformation mechanisms and processing constrains. This paper presents the results of simulation of different rolling schedules applied on pipeline grades in order to better understand the influence of the finishing rolling parameters namely: finish rolling temperature (FRT) and cooling routes on the microstructure and mechanical properties. It was observed that FRT and cooling rate have a strong impact on both grain refinement and precipitation behaviour, which leads to significant differences in strength and toughness. Furthermore variations of the above mentioned rolling parameters produce distinct fractions and distributions of austenite transformation products, variations in the final crystallographic texture and trigger diverse strengthening mechanisms (i.e. dislocation hardening). It was found that the accelerated cooling in a combination with a coiling simulation results in formation of microstructures with well developed low angle grain boundaries in comparison to the simulation made with air cooling. As a consequence the strength of the plates after accelerated cooling increases without changes in the Charpy impact toughness. It has been shown that the understanding of the effect of processing parameters on the microstructure of these steels is a key aspect for the optimization of their mechanical properties.
Physical Simulation for Evaluating Heat-Affected Zone Toughness of High and Ultra-High Strength Steels
Authors: Laitinen Risto O. , Porter David A. , Karjalainen L. Pentti , Leiviskä Pasi , Kömi Jukka
Published: July 2013

Physical simulation of the most critical sub-zones of the heat-affected zone is a useful tool for the evaluation of the toughness of welded joints in high-strength and ultra-high-strength steels. In two high-strength offshore steels with the yield strength of 500 MPa, the coarse grained, intercritical and intercritically reheated coarse grained zones were simulated using the cooling times from 800 to 500 °C (t8/5) 5 s and 30 s. Impact and CTOD tests as well as microstructural investigations were carried out in order to evaluate the weldability of the steels without the need for expensive welding tests. The test results showed that the intercritically reheated coarse grained zone with the longer cooling time t8/5=30 s was the most critical sub-zone in the HAZ due to the M-A constituents and coarse ferritic-bainitic microstructure. In 6 mm thick ultra-high-strength steel Optim 960 QC, the coarse grained and intercritically reheated coarse grained zones were simulated using the cooling times t8/5 of 5, 10, 15 and 20s and the intercritical zone using the cooling times t8/5 of 5 and 10 s in order to select the suitable heat input for welding. The impact test results from the simulated zones fulfilled the impact energy requirement of 14 J (5x10 mm specimen) at -40 °C for the cooling times, t8/5, from 5 to 15 s, which correspond to the heat input range 0.4-0.7 kJ/mm (for a 6 mm thickness).
Hardness Profiles of Quenched Steel Heat Affected Zones
Authors: Heikkilä S.J. , Porter David A. , Karjalainen L. Pentti , Laitinen Risto O. , Tihinen S.A. , Suikkanen Pasi
Published: July 2013

This paper reports the effects of chemical composition on the hardness of the heat affected zone of re-austenitized and water quenched steels. Heat affected zone peak temperatures in the range 300–1350 °C were simulated using a Gleeble 3800 simulator using thermal cycles appropriate to welds with cooling times between 800 and 500 °C of 12s. The maximum softening relative to the base material occurred in the intercritical and subcritical heat affected zones at the peak temperatures of 700 or 800 °C. Usually softening was greatest when the peak temperature was 700 °C. Linear regression analysis showed that carbon, and to some extent manganese and nickel, are detrimental at the peak temperature of 700 °C, but beneficial at the peak temperature of 800 °C in respect to softening relative to the base material, whereas niobium and especially molybdenum are beneficial at both temperatures. The beneficial effects of molybdenum alloying are seen down to peak temperatures of 400 °C whereas the effect of niobium microalloying is not statistically significant at peak temperatures lower than 700 °C. The softening in the intercritical, fine-grained and coarse grained heat affected zones are discussed and the effects of the alloying elements on the hardness of the subcritical heat affected zone are compared with their known effects on martensite hardness during conventional tempering.
Modelling the Hot Deformation Stress-Strain Curve of a Ni-Based Superalloy
Authors: Kodzhaspirov G.E. , Borowikow A. , Terentyev M.
Published: July 2013

A study on the hot deformation behavior and microstructural changes of nickel based superalloy are presented. Constitutive equation allowing the calculation of peak stress was derived. A study of the effect of the temperature-deformation parameters on the kinetic of austenitic heat-resistant superalloy dynamic recrystallization and on the microstructure evolution was performed as well.
Forecasting of Hard-Alloyed Cutting Tool Resistance Based on Thermal Diffusivity
Authors: Bibik Vladislav L.
Published: July 2013

The paper contains the description of a method, equipment and results for predicting the wear resistance of cemented carbide cutting inserts by measuring their thermal diffusivity. Strong correlation between wear resistance and thermal diffusivity was found. This presented method has been patented.
The Effectiveness of Counter‐Terrorism Strategies
Authors: Lum Cynthia , Kennedy Leslie W. , Sherley Alison J.
Published: July 2013

The objective of this Campbell systematic review is to determine the effectiveness of counter‐terrorism strategies from the available social scientific research literature using systematic review methods.

From over 20,000 studies we located on terrorism, we found only seven which contained moderately rigorous evaluations of counterterrorism programs. We conclude that there is little scientific knowledge about the effectiveness of most counter‐terrorism interventions. Further, from the evidence we were able to locate, it appears that some evaluated interventions either didn't work or sometimes increased the likelihood of terrorism and terrorism‐related harm.

The findings of this review dramatically emphasize the need for government leaders, policy makers, researchers, and funding agencies to include and insist on evaluations of the effectiveness of these programs in their agendas. These agendas would include identifying ways to overcome methodological and data challenges often associated with terrorism research, increasing funding to evaluate existing programs through methodologically rigorous evaluation designs, and paying attention to existing evaluations of programs when implementing them. Further, programs should be assessed to establish if they cause more harm than good or if they create unanticipated consequences.
Approaches to Parent Involvement for Improving the Academic Performance of Elementary School Age Children
Authors: Nye Chad , Turner Herb , Schwartz Jamie
Published: July 2013

This Campbell systematic review's objective is to summarize the most dependable evidence on the effect of parental involvement intervention programs for improving the academic performance of elementary school age children. The most dependable evidence is defined as studies that include at least two groups and use random assignment to form a fair comparison between groups.

19 Randomised Controlled Trials met the inclusion criteria for the systematic review. The overall findings were that parent involvement has a positive and significant effect on children's overall academic performance. It is also clear that the effect is large enough to have practical implications for parents, practitioners, and policymakers (d= 0.45).

The overall effect suggested that when parents participated in academic enrichment activities with their children outside of school, the benefits were manifest in improved academic performance in school. This result was striking when one considers that the median length of parent involvement was only 11 weeks. This review has uncovered compelling support for the use of a parent involvement program as a viable supplementary intervention to improve children's academic performance in school, and for the parent involvement component of the No Child Left Behind mandate.
Corrosion of X-65 Pipeline Steel Under a Simulated Cathodic Protection Shielding Coating Disbondment
Authors: Eslami A. , Kania R. , Worthingham B. , Boven G.V. , Eadie R. , Chen W.
Published: July 2013

Pipeline corrosion is a common problem for polyethylene (PE) tape-coated oil and gas transmission pipes buried under ground. It is often seen under cathodic protection (CP) shielding coating disbondments, where a wrinkle filled with ground water could be formed. This study investigates corrosion of X-65 pipeline steel under a simulated CP shielding coating disbondment with a gap size of 1 cm. Results showed that the corrosion rate of pipeline steel under the CP shielding coating disbondments is a function of carbon dioxide (CO2) and level of CP at the holiday of the coating disbondment, and could be significantly different to that in bulk environments.
Effective Hydrogen Diffusion in Aluminum Alloy 5083-H131 as a Function of Orientation and Degree of Sensitization
Authors: Ai Jia-He , Lim Mary Lyn C. , Scully John R.
Published: July 2013

The effective hydrogen diffusivity in aluminum alloy (AA)5083- H131 (UNS A95083) for various orientations and degrees of sensitization (DoS) was investigated using AA5083/Pd bilayer membranes. Sensitization produced β-phase (Al3Mg2) precipitates. A modified Devanathan-Stachurski permeation method was used with hydrogen charging by open-circuit exposure to 0.01 M sodium hydroxide (NaOH) and detection via Pd hydride formation. The measured hydrogen diffusivity (DH,eff) in the longitudinal (L) or short transverse (S) direction was almost independent of AA5083 foil thickness, indicating bulk diffusion control. DH,eff was not sensitive to the DoS, ranging from 2 mg/cm2 to 49 mg/cm2. The average room temperature diffusivities of hydrogen, DH,eff (25°C), for the initial H charging cycle of as-sensitized foils, were determined by the slope (Lcorr2/6 vs. t) method to be 8.5 (±1.4) × 10−11 cm2/s along the S direction and 1.4 (±0.2) × 10−10 cm2/s along the L direction, with a 95% confidence level. By averaging individual measured data points, DH,eff (25°C) was found to be 1.0 (±0.3) × 10−10 cm2/s along the S direction and 1.5 (±0.4) × 10−10 cm2/s along the L direction. The effective diffusivity of hydrogen increased by one to two orders of magnitude during the second and third hydrogen charging cycles. This charge cycle dependency was interpreted to result from extensive hydrogen trapping in uncharged foils and remaining trap site occupancy after initial precharging. The implication of these results toward intergranular stress corrosion involving hydrogen-controlled cracking of inter-β ligaments between closely spaced, quickly dissolving β-phase precipitates on grain boundaries is discussed.