bluuebunny/crossref_metadata_2025 huggingface dataset:
Cold-Metal-Transfer Arc Joining of Al 6K32 Alloy to Steel Sheets
Authors: Kang Min Jung , Kim Cheol Hee
Published: March 2013

In the arc joining of dissimilar metals, such as steel and Al alloys, a brittle intermetallic phase is formed at the interface. The thickness of this phase should be minimized because it causes solidification cracking. Cold metal transfer (CMT) arc welding technology is widely used throughout the automotive industry because of low spatter formation and heat input. A CMT arc was used to investigate arc joining between the Al 6K32 alloy and mild steel sheets. The behaviors of the interface layers were analyzed on the basis of filler wires and the coating type of the steel sheets. The thickness of the intermetallic phase was maintained under 10 μm and increased joint strength was achieved by selecting the appropriate filler wire and coating type.
Customer Satisfaction Model in Nano Food Products Using by Customer Knowledge Management (CKM) Approach
Authors: Farhadyar A. , Griguryan K. , Farhadyar Nazanin , Farhadyar F.
Published: March 2013

In the emphasis on knowledge as a key competitive factor in the global economy, corporations may be overlooking a major element customer knowledge. Customer knowledge management (CKM) creates new knowledge sharing platforms and processes between companies and their customers. Customer education is one of the best ways of Customer knowledge management. Despite companies growing interest for customer education and the recent awareness in marketing literature of this concept, research on customer education remains relatively scarce. In this research a model which details the relationships between customer education and customer satisfaction was proposed and validated for nanofood product. The existence of two mediating variables was unveiled: product usage and product-usage related knowledge and skills. The experimental fieldwork was conducted in partnership with nanofood companies and their customers. In this research, clear evidence has been provided that customer education positively impacts on customer satisfaction and that specific mechanisms explain such effects.
Investigation of Salt Diffusion in Soil by Using Radiotracing Technique
Authors: Baytaş A.F. , Tugrul A.B. , Gökbulak F. , Baydogan Nilgun , Altinsoy N. , Haciyakupoğlu S. , Karatepe N. , Erentürk S. , Büyük B. , Demir E. , Camtakan Z.
Published: March 2013

In this study, it is aimed to observe diffusion of sodium in soil samples by using radiotracing technique. To produce the radiotracer 24Na, sodium-carbonate compound was irradiated at ITU TRIGA Mark II Research reactor at Energy Institute of Istanbul Technical University. The irradiated sodium-carbonate samples were sprinkled to the surface of soil columns. Then soil was watered with representative amounts of water according to selected rain regimes in Istanbul. Radioactivity measurements were carried out by using high efficiency gamma-ray measurement system at the outside of the column for different soil depths in different times.
The Process of Tungsten-Nitride Precipitation upon Nitriding Ferritic Fe-0.5 at.% W Alloy
Authors: Schwarz Benjamin , Hörth Regina E. , Bischoff Ewald , Schacherl Ralf E. , Mittemeijer Eric Jan
Published: March 2013

The precipitation of tungsten nitride upon internal nitriding of ferritic Fe-0.5 at.% W alloy was investigated at 610°C in a flowing NH3/H2 gas mixture. Different tungsten nitrides developed successively; the thermodynamically stable hexagonal δ-WN could not be detected. The state of deformation of the surface plays an important role for the development of tungsten nitride at the surface. The morphologies of the tungsten nitrides developed at the surface and those precipitated at some depth in the specimen are different. The nitride particles at the surface exhibit mostly an equiaxed morphology (with the size of the order 0.5 µm) and have a crystal structure which can be described as a superstructure derived from hexagonal δ-WN. These nitride particles show a strong preferred orientation with respect to the specimen frame of reference but have no relation with the crystal orientation of the surrounding ferrite matrix. In the bulk, nanosized and finely dispersed platelet-like precipitates grow preferentially along {100}α-Fe. It is unclear whether these precipitates consist of binary iron nitride α´´-Fe16N2 or of a ternary Fe-W-N. Additionally to the finely dispersed particles, bigger nitrides at ferrite grain boundaries develop exhibiting platelet-type morphology and possessing a crystal structure which can be also described as a superstructure derived from hexagonal δ-WN. Upon prolonged nitriding assumed discontinuous precipitation of the initially precipitated finely dispersed nitrides starts from the ferrite-grain boundaries resulting in lamellas consisting of alternate ferrite and hexagonal nitride lamellas, whereas the nitride lamellas having a Pitsch-Schrader orientation relationship with the surrounding ferrite matrix. The nitrides precipitated upon nitriding in the bulk were found to be unstable during H2 reduction at 470°C. Remarkably, upon such low temperature dissolution of the nitrides took place but only the nitrogen from the nitride particles could diffuse out of the nitride platelets and the specimen, leaving W-rich regions (W-clusters) at the location of the original precipitates.
Surface Characterization of Irradiated Zno:Al Thin Film by Reactor Neutrons
Authors: Baydogan Nilgun , Çilingiryan K. , Tugrul A.B. , Çimenoğlu H. , Yeşilkaya S.S.
Published: March 2013

rradiation of ZnO:Al thin film by reactor neutrons with neutron/gamma ratio at 1.44x104 (n.cm-2.s-1.mR-1) leads to a decrease in resistivity in this material. The observed effects in electrical resistivity are attributed to irradiation-induced formation of defects in the ZnO:Al thin film structure.
Growth of Calcium Phosphate Coating on Ti-7.5Mo Alloy after Anodic Oxidation
Authors: Escada A.L.A. , Machado João Paulo Barros , Nakazato Roberto Zenhei , Rosifini Alves Claro Ana Paula
Published: March 2013

Titanium and its alloys are widely used as biomaterials due to their mechanical, chemical and biological properties. To enhance the biocompatibility of titanium alloys, various surface treatments have been proposed. In particular, the formation of titanium oxide nanotubes layers has been extensively examined. Among the various materials for implants, calcium phosphates and hydroxyapatite are widely used clinically. In this work, titanium nanotubes were fabricated on the surface of Ti-7.5Mo alloy by anodization. The samples were anodized for 20 V in an electrolyte containing glycerol in combination with ammonium fluoride (NH4F, 0.25%), and the anodization time was 24 h. After being anodized, specimens were heat treated at 450 °C and 600°C for 1 h to crystallize the amorphous TiO2 nanotubes and then treated with NaOH solution to make them bioactive, to induce growth of calcium phosphate in a simulated body fluid. Surface morphology and coating chemistry were obtained respectively using, field-emission scanning electron microscopy (FEG-SEM), AFM and X-ray diffraction (XRD). It was shown that the presence of titanium nanotubes induces the growth of a sodium titanate nanolayer. During the subsequent in-vitro immersion in a simulated body fluid, the sodium titanate nanolayer induced the nucleation and growth of nanodimensioned calcium phosphate. It was possible to observe the formation of TiO2 nanotubes on the surface of Ti-7.5Mo. Calcium phosphate coating was greater in the samples with larger nanotube diameter. These findings represent a simple surface treatment for Ti-7.5Mo alloy that has high potential for biomedical applications.
Infiltration in Porous Media Using Centrifuge with Moving Arm
Authors: Kačur Jozef , Minár J. , Budáčová Hana
Published: March 2013

Numerical modelling of unsaturated-saturated flow under centrifugation with moving arms is studied. A numerically efficient approximation is presented for mathematical model based on Richard's nonlinear and degenerate equation expressed in terms of effective saturation using Van Genuchten-Mualem ansatz with soil parameters in unsaturated zone. The method is suitable for determination of soil parameters via the solution of inverse problem in an iterative way. Using centrifuge offers significant time savings and provides us with many data for the parameter estimation. The present implementation of our method requires only very cheap measurements of global characteristics.
Degradation Control of Walls with Rising Damp Problems
Authors: Guimarães A.S. , Delgado João M.P.Q. , de Freitas V.P.
Published: March 2013

Degradation in walls of Historical Building with rising damp is a complex problem to solve, due to the thickness and heterogeneity of those walls. The traditionally treatment techniques used (such as watertight barriers, injection of hydrofuge products, etc.) show, sometimes, to be ineffective or too expensive, justifying the need to find a new approach. Experimental studies validate the effectiveness of a new treatment technique applied to the walls of old buildings wall base ventilation system.
Building Physics Laboratory (LFC) is developing a model of this technique. The sizing of the treatment system is based on knowledge of the characteristics of the wall, of the geometry of the ventilation system and of the building being dealt with.
In this work it is described the moisture transfer process between the moving air flux, inside the system, and the wall. Experimental results were used to validate the mathematical solution and the values obtained are very similar.
Mechanical Properties Gradient Existing in Real Castings Taken into Account during Design of Cast Components
Authors: Ignaszak Zenon , Hajkowski Jakub , Popielarski Paweł
Published: March 2013

The problem concerns the structure and properties heterogeneity of cast products, on the example of the Al-Si (A356) alloy. The trends of usage of this knowledge by constructors of that kind of products are described in this paper. It is well known that soundness of cast products is a postulate formulated by designers and users of machines and devices, where castings are among important parts. It is often forgotten though, that perfect soundness (density) of the cast material in ready for use parts simply does not exist. The gas and shrinkage porosities, present in semi-finished casting products, obtained from a liquid state of an alloy is the result of phenomena occurring during multiphase metallic system crystallization. Still, general introduction of the tolerance of damage rule requires knowledge about casting technology, inspection of the state of discontinuity of casting structure. The use of coupled experimental researches (including NDT non-destructive testing and local mechanical properties of castings) and simulation tests (Procast, ANSYS) have shown how the properties gradient influences on the safety factor distribution in the casting subjected by chosen load.
Ammonia Synthesis Using Magnetically Induced Reaction
Authors: Yahya Noorhana , Puspitasari Poppy , Noordin Nor Hasifah
Published: March 2013

Ammonia production is a high energy and capital intensive industry as it requires high temperature (400500°C) and high pressure (150300 bar) for its daily operations. By introducing nanocatalyst with the new concept of micro-reactor with applied magnetic field induction, the catalytic activity can be induced and the output can be enhanced. Magneto-dynamics will be introduced in the ammonia production process in order to replace the concept of thermodynamics in the Haber Bosch process. The nanocatalysts (Y3Fe5O12, Fe2O3, MnO, Mn0.8Zn0.2Fe2O4) have been reduced by using the temperature reduction method (TPR). The Y3Fe5O12 (YIG) catalyst with magnetic induction produced242.56µmol/h.g-cat output of ammonia which is 2% much higher than ammonia synthesis without magnetic induction (237.52 µmol/g.h).The ammonia output based on the magnetic induction method at a temperature of 0°C is 242.56µmole/h.g-cat which is 0.90% higher than the synthesis at 25°C temperature (240.4 µmol/g.h). The ammonia output at 0.2Tesla is 249.04 µmole/h.g-cat which is higher 2.6% than the output at 0.1Tesla which is 242.56µmol/g.h. It is proven that the higher the applied magnetic field is, the more effective the catalytic activity will be as a better alignment of the electron spin of the catalyst occurs and enhances the adsorption and desorption process. Y3Fe5O12 (YIG) shows the best catalytic reaction followed by Fe2O3 (hematite) and MnO (manganese oxide). By this new route, synthesis of ammonia at low temperature is realized and offers ammonia producers an economic advantage compared to the classical routes.
Salt Degradation in Stone of Old Buildings
Authors: Delgado João M.P.Q. , de Freitas V.P.
Published: March 2013

The crystallization of soluble salts is a major mechanism of degradation of some building materials, including stone. This mechanism of deterioration is based on the pressure exerted by the formation of salt structures in porous materials, with increased volume and is dependent on the type of salts involved and the size and arrangement of pores. When the pressure exceeds the internal strength of the material, and particularly when the salt formations undergo cycles of crystallization and dissolution in response to fluctuating levels of humidity, the deterioration of materials typically becomes apparent. It is therefore essential to understand the phenomenon of crystallization and dissolution of salts, i.e., to know the conditions of crystallization of each salt, depending on relative humidity and air temperature. For this purpose we developed an experimental work, using four samples of stone (one limestone and three granites), which consists, initially, to study the variation of the water absorption coefficient with and without soluble salts.
Capacitance-Voltage (C-V) Properties of ZnO:Al/p-Si Heterojunctions
Authors: Baydogan Nilgun , Gokce Y. , Baydogan Murat , Çimenoğlu H.
Published: March 2013

ZnO:Al/p-Si heterojunctions were fabricated by sol-gel dip coating technique onto p-type Si wafer substrates. Capacitance-Voltage (C-V) characteristics of ZnO:Al/p-Si heterojunctions were determined after the ZnO:Al thin film coated Si wafers were annealed at 700 and 800°C, respectively. C-V results indicate an abrupt interface.
Sewage Sludge Flow and Drying Characteristics in Paddle Dryers
Authors: Zhang Hou Lei , Liu Xin Zhi , Zhu Shu Guang , Li Bin
Published: March 2013

Sewage sludge from wastewater treatment is being more and more produced in many countries. For sewage sludge disposal, drying operation is usually required and greatly energy-consuming. Paddle dryers, one kind of indirect dryers, are widely used in removing moisture of sewage sludge recently, but the design, to some extent, still depends on empirical and limited data. In this paper, we presented preliminary experimental results of sewage sludge drying based on a 3 m2 paddle dryer prototype. The effects of thermal oil inlet temperature on outlet moisture content and mass flowrate of initial sludge are recorded and analyzed. A simple monotonic relation between mass flowrate of initial sludge and thermal oil inlet temperature does not exist. Besides, we performed the drying experiment of adding low-value biomass (rice husk) into wet sewage sludge. The results show that the drying performance is improved significantly.
The Influence of some Physical Variables in the Capillarity Rise of Different Monolithic Walls
Authors: Delgado João M.P.Q. , Guimarães A.S. , de Freitas V.P.
Published: March 2013

Humidity, particularly rising damp, is one of the main causes of degradation of historical constructions. This type of humidity manifestation appears when the constituent materials of the walls exhibit high capillarity and these walls are in contact with water or wet soil. The treatment of rising damp in historical buildings walls is very complex. Moisture transfer in walls of old buildings, which are in direct contact with the ground, leads to a migration of soluble salts responsible for many building pathologies. In this work a sensibility study was done, using an automatic calculation program, WUFI 2D v.3.3, with the main goal to determinate the influence of some variables in the capillarity rise of different monolithic walls, namely the importance of material properties (as porosity), exterior climate and wall thickness.
The Reducibility of the Iron Ore Materials as Instrument of the Coke Consumption Decrease in the Blast Furnace Smelting
Authors: Dmitriev Andrey N. , Chesnokov Yu.A. , Vitkina Galina Yu.
Published: March 2013

The technique of defining the minimum coke consumption in blast furnace smelting allows for the calculation of the reserve of coke economy on the basis of thermodynamic principles. In this reserve the constitutive role belongs to the reducibility of the iron ore materials (the agglomerate and pellets). In the present paper, the questions of the reduction kinetics of the iron ore materials and diffusion processes at reduction of iron from its oxides are considered. It is shown that the reducibility of the iron ore materials is the basic reserve of economy the scarce and expensive coke in the blast furnace smelting.
Nanozirconium Carbide Powder Synthesis via Carbothermal Route
Authors: Arianpour F. , Kazemi F. , Rezaie Hamid Reza , Asjodi A. , Liu J.
Published: March 2013

Zirconium carbide (ZrC) has extended application in many ceramic and metal matrix composites especially used for ultra high temperature conditions. The synthesis of zirconium carbide powder is costly and difficult because of its high refractoriness and chemically inert properties. In this research, the synthesis of zirconium carbide nanopowder at low temperature via carbothermal reduction route was investigated according to thermodynamic data. The starting materials were zirconium acetate and sucrose as zirconium and carbon sources, respectively. After preparation of different carbon/zirconium ratio containing precursors, the dried precursors were heat treated at 1400°C and vacuum atmosphere. Also the ZrC formation was followed by thermal analysis of the produced precursors. The phase evolutions and microstructural studies were carried out using X-ray diffraction and scanning electron microscopy. The results showed that it is possible to synthesis zirconium carbide nanopowder with round shape and crystallite sizes smaller than 20 nm at low temperatures. Also according to thermodynamic calculations, it was concluded that by applying vacuum condition, the zirconium carbide formation can occur at less than 1000°C which is very effective on the size reducing of produced ZrC nanopowders.
Quality Improvement and Characteristics of Polyhydroxyalkanoates (PHAs) and Natural Latex Rubber Blends
Authors: Kaewkannetra Pakawadee , Promkotra Sarunya
Published: March 2013

Biopolymers of hard, brittle and low flexible polyhydroxyalkanoates (PHAs) and a soft and high elastic natural-latex rubber are blended at room temperature by using a combination technique. Concentrations of the PHAs solution are constituted at 1%, 2% and 3% w/v and mingled with fresh natural latex in different ratios (PHAs : Latex Rubber = 0:10, 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1 and 10:0). After vigorous blending, forming polymeric sheets leave a dried-film pattern. Only the best 3 different ratios (4:6, 5:5 and 6:4) are selected by evaluating morphological-based information. These lead to actually define and characterize for their morphological and mechanical properties. The morphological attributes are exemplified by polarized optical microscopy and X-ray diffractometry (XRD) while the thermal characterization is determined by differential scanning calorimetry (DSC). Morphological analysis for the criterion of blending achievement indicated that there is a significant relationship among porosity, texture and shrinkage. The porosity shows obviously low to high for gradually increasing PHAs and decreasing the latex. Thus, dense texture and shrinkage relate to blending compositions between PHAs and latex. The XRD and DSC reveal certain aspects of decreasing crystallinity arising from enhancing of the latex content. A high degree of crystallinity and melting temperature relates to greater PHAs ratio. The mechanical investigations have revealed complex localization patterns of tensile strength and elastic modulus. The more PHAs concentration at 2% w/v indicates the greater elastic modulus than 3% and 1% w/v. Significant differences are found on polymeric composites of mechanical analyses between PHAs and natural latex. The constituted superiority in the ratio of 5:5 significantly differs in extension to break. Additionally, both tensile strength and elastic modulus of 2% w/v PHAs present the maximum value among them.
Synthesis and Thermal Stability of Nontransformable Tetragonal (ZrO2)0.96(REO1.5)0.04 (Re=Sc3+, Y3+) Nanocrystals
Authors: Loghman-Estark Mohammad Reza , Razavi Reza Shoja , Edris Hossein
Published: March 2013

Scandia, yttria doped zirconia ((ZrO2)0.96 (REO1.5)0.04 (RE=Sc3+, Y3+)) nanoparticles were prepared by the modified sol-gel method. The microstructure of the products was characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. Thermal stabillity of SYSZ nanocrystals were also investigated. The SYSZ nanocrystals synthesized with EGM:Zr+4 mole ratio 4:1, calcined at 700°C, have average diameter of ~20 nm.
Transportation and Manufacturing Technology System (TMTS) Vibro-Impact Treatment of Large Pieces
Authors: Saidi Djamel , Bouaziz M. , Babichev Anatoly P. , Hamouda Khaled , Djema M.A. , Siguerdjidjene H.
Published: March 2013

Present paper, introducing a new method of mechanical preparation of specific surfaces in a liquid medium by using unguided tools. All the presented work is originally approach based on the search of mechanics contact behaviour laws in a liquid medium. It promotes the operations of deburring and polishing, whilst causing a hardening, by varying the experimental conditions (material type, treatment time, presence or absence of chemical additions). This method was used for large dimensions pieces in order to treat the inner and outer surfaces.
Identification of Surface Quality of Plastic Electrodes after Blasting
Authors: Haluzíková B. , Valíček Jan , Škubala P. , Harničárová Marta , Bražina D. , Szarková V. , Koštial Pavel , Kušnerová Milena , Rokosz Krzysztof , Tomkowski R. , Kapłonek W.
Published: March 2013

Nowadays, plastics have become one of the most demanded materials, replacing the traditional ones such as metals. Therefore, many companies are concerned with the production of plastics, with their distribution and innovation development. Plastics have found utility in a wide range of applications, we use them every day. Measurement of surface roughness of plastic moldings produced by the injection molding process was carried out by a contact profilometer Mitutoyo Surftest SJ401. A reason for this measurement is to obtain information about surface roughness. For further technical adjustment is required to have higher surface roughness what helps to increase electrical conductivity of plastic moldings. This involves determination of a ratio between Ra/Rz (the ratio between the arithmetic average of the roughness profile Ra and the average maximum height of the profile Rz) in order to satisfy customer demand for achieving better surface characteristics leading to an increase in electrical conductivity.
Diffusion of Palm Biodiesel in Elastomers Undergoing Multiaxial Large Deformations
Authors: Ying Ch’ng Shiau , Andriyana A. , Verron Erwan , Ahmad Roslina
Published: March 2013

Petroleum-based fuel is facing significant depletion issue due to its limited reserves and increasing demand from various industries. Thus, various considerations from economical, environmental and political concerns have motivated researchers to develop alternative energy sources such as biofuel to decrease dependence on petroleum-based fuel. However, the changes in the fuel composition of biofuel affect the material compatibility. In engineering applications where elastomeric components are exposed to hostile environment such as palm biodiesel medium, at least two aspects contribute to the degradation of the materials during the service: diffusion of the liquids leading to swelling and fluctuating multiaxial mechanical loading leading to fatigue failure. Therefore, it is of utmost importance to study the mechanical responses of elastomers under this coupled diffusion-mechanical loading in order to predict accurately their fatigue failure. The present work investigates the swelling of elastomers under simultaneous diffusion of palm biodiesel and multiaxial large deformations.
Tribological Investigations of TiC+a-C:H Coatings Manufactured on X38CrMoV5-1 Steel Using PVD Technology
Authors: Golabczak Marcin , Jacquet Philippe , Nouveau Corinne , Fliti Romain
Published: March 2013

X38CrMoV5-1 steel is a typical tool steel commonly used in forging and plastic moulding industry for production of ejectors, slides, dies, etc. In plastics moulding a lot of these parts sustain relative movement. Because of this, some seizing or micro-welding may appear, especially when lubrication is not used. For many years, the different types of protective coatings were developed to avoid such problems. Most of the obtained solutions relate to the manufacturing of low friction coatings obtained by different nitriding processes and by CVD or PVD methods. In this article, the friction coefficients and the wear resistances of TiC+a-C:H protective coatings manufactured on X38CrMoV5-1 steel samples by using PVD technology are studied. The investigations are based on tribometer tests in different temperature conditions. The process of deposition of PVD coatings was realized by using multisource, hybrid factory-scale equipment of type URM 079. This equipment allows for deposition of coatings by a physical method. The tribological tests were performed using a precision high temperature tribometer under ambient and high temperature conditions with a steel and corundum balls as a counter-samples. In this paper, the results of these tribological tests are presented. It is shown that the measured friction coefficient of steel samples with PVD coatings is significantly lower than the friction coefficient of uncoated steel. It is also shown that X38CrMoV5-1 steel samples with manufactured TiC+a-C:H coatings are characterized by a very low friction coefficient and high wear resistance.
Effect of Salty Development on Forming HSQ Resist Nanodot Arrays with a Pitch of 15×15 nm2 by 30-keV Electron Beam Lithography
Authors: Komori Takuya , Zhang Hui , Akahane Takashi , bin Mohamad Zulfakri , Yin You , Hosaka Sumio
Published: March 2013

We investigated the effect of ultrahigh-resolution salty (NaCl contained) development of hydrogen silsesquioxane (HSQ) resist on forming fine dot arrays with a pitch of 15×15 nm2 by 30-keV electron beam lithography for patterned media. The optimized concentration of resist developers was determined to fabricate most packed pattern. We found that increasing the concentration of NaCl into tetramethyl ammonium hydroxide (TMAH) could greatly improve the resist contrast (γ-value) of HSQ. And by using 2.3 wt% TMAH/4 wt% NaCl developer, we demonstrated 15×15 nm2 pitched (3 Tbit/in.2) HSQ resist dot arrays with a dot size of < 10 nm.
Visible-Light Emission Properties of Erbium-Doped Tantalum-Oxide Films Produced by Co-Sputtering
Authors: Singh Mayank Kumar , Miura Kenta , Fusegi Genjoh , Kano Kazusa , Hanaizumi Osamu
Published: March 2013

The visible-light emission properties of erbium (Er)-doped tantalum-oxide films prepared by co-sputtering were evaluated. Photoluminescence (PL) peaks at wavelengths of 550 and 670 nm could be observed from these films by ultraviolet-laser excitation after annealing. The dependence of Er3+ concentration, annealing temperature, and annealing time on the PL peak intensities were investigated. Such light-emitting sputtered films can be useful as high-index materials of photonic crystals that can be applied to novel active devices.
One-Dimensional Long Range Order of Autocorrelation Functions for Polyethylene Type Clusters Using the DV-Xα Method
Authors: Kobayashi Kohjiro , Suzuki Kosuke , Sakurai Hiroshi
Published: March 2013

sotropic and directional autocorrelation functions have been calculated using the DV-Xα method on polyethylene type clusters to investigate the effect of its characteristic dimensionality of the wavefunctions. Directional autocorrelation functions are calculated along the c-axis, the direction of the long chain of carbon atoms, and along an axis perpendicular to it. The analysis of the molecular orbital dependence of the autocorrelation function reveals that the long range order along the c-axis can be enhanced as increasing the length of the cluster and the orbitals near the highest occupied molecular orbital have a key role for the one-dimensional order.
A Study on the Class of Model Feedback Controllers Formultiple-Input/Multiple-Output Non-Minimum Phase System
Authors: Hagiwara Takaaki , Yamada Kou , Hoshikawa Tatsuya , Karasawa Yuuto , Kanno Fuminori
Published: March 2013

In the present paper, we examine model feedback control systems (MFCSs). BecauseMFCS is simple, the MFCS has been applied in many applications such as the trajectorycontrol of robot manipulators, serially connected water tanks, etc. The control structure of theMFCS is limited, but Yamada and Moki reported about whether or not MFCS can representall stabilizing controllers of a minimum phase plant. However, no research has been reportedwhether or not MFCS can represent all stabilizing controllers of a non-minimum phase plant.The purpose of the present paper is to give a solution to the question as to whether or not allstabilizing controllers for a plant are expressible in the MFCS structure. The relation betweenMFCS and the parameterization of all stabilizing controllers for a class of non-minimum phasemultiple-input/multiple-output plants is shown. A simple design method to specify controlcharacteristics is also presented.
Single Inductor Bipolar Outputs DC-DC Converter with Current Mode Control Circuit
Authors: Takai Nobukazu , Okada Takashi , Takahashi Kenji , Yokoo Hajime , Miwa Shunsuke , Tsushida Kengo , Iwase Hiroyuki , Murakami Kazuki , Kobayashi Haruo , Odaguchi Takahiro , Takayama Shigeki , Oomori Takeshi , Nakanishi Isao , Nemoto Kenji , Matsuda Junichi
Published: March 2013

Mobile equipment such as organic-EL display, digital still camera and so on re-quire both positive and negative power supply voltage to obtain high quality. Single InductorMultiple-Output (SIMO) DC-DC converter can provide a pair of positive and negative outputvoltages with only one external inductor. This paper describes SIMO DC-DC Converter usingproposed current-mode control (CMC) circuit. The proposed CMC circuit realizes high responsespeed for the change of load current. Spectre simulations with 0.18m CMOS process parameterare performed to verify the validity of the proposed converter. The simulation results indicatethat the proposed converter has higher response time compared with conventional converter.
Desialylation of N-Linked Carbohydrate Chain of Fibrinogen
Authors: Kubota Kenji , Toyama Yoshiharu , Nameki Nobukazu , Wakamatsu Kaori
Published: March 2013

Acceleration of fibrin polymerization occurs by the cleavage of sialic acids at the nonreducing terminal ends of N-linked carbohydrate chains as well as the cleavage of the entity of carbohydrate chains. In order to characterize and clarify the role of terminal sialic acid in the fibrin polymerization, mixing effects of desialylated fibrinogen with the intact one on the polymerization behavior were investigated by turbidity measurements in the course of polymerization. Marked accelerated fibrin polymerization was observed for the mixing of even a little amount of desialylated fibrinogen. Cleavage of the terminal sialic acid resulted in almost the equivalent accelerating effect to those of the deglycosylated fibrinogen, in which the entity of N-linked carbohydrate chain was cleaved. These results suggest that the terminal sialic acids regulate the fibrin polymerization in an inhibitory manner, and the cleavage of them induces the switchover from the protofibril growth to the lateral aggregation of fibrin polymerization process, resulting in the preferential fibrin polymerization.
Anisotropy Evaluation of In Vivo Tissue Elasticity Measurement by Using Wavenumber Filtering
Authors: Miwa Takashi , Yamakoshi Yoshiki
Published: March 2013

Tissue elasticity measurements by an ultrasonic wave are a promising technique to qualitative diagnosis of tumor or liver diseases. The elasticity in the soft tissue can quantitatively be estimated by velocity of a shear wave propagating through the tissue. For safer and more accurate estimation of the velocity, an elasticity imaging method using continuous vibration wave excitation has been proposed. This method utilizes wave number vector analysis to individually estimate the velocity of the shear waves generated by multiple reflections. In this paper, applicability of the wave number filtering method is discussed to separate the plural shear waves through a phantom experiment. Then, an in-vivo experiment shows possibility to extract anisotropic information of muscle fiber for applying the tissue elasticity measurement.
Electrical Conductivity of Li2xZn2-3xTi1+xO4 Crystal
Authors: Furusawa Shinichi , Koyama Yuusuke
Published: March 2013

Li2xZn2-3xTi1+xO4(x=0.33, 0.50, 0.60) crystals were grown in a double-mirror type optical floating-zone furnace. The electrical conductivity of Li2xZn2-3xTi1+xO4of crystal was measured in a frequency range from 100 Hz to 10 MHz and in a temperature range from 330 to 700 K, in nitrogen gas. It was revealed the electrical conductivity mechanism changes at the temperature region of 480520 K. The electrical conductivity of polycrystalline Li2xZn2-3xTi1+xO4(x=0.6) shows nearly two orders of magnitude higher values compared to other samples.
Effect of Metal Modification to Carbon Paper Anodes on the Performance of Yeast-Based Microbial Fuel Cells Part Ι: In the Case without Exogenous Mediator
Authors: Kasem Enas Taha , Tsujiguchi Takuya , Nakagawa Nobuyoshi
Published: March 2013

Effect of modification of carbon paper with a thin layer of cobalt or gold on the performance of yeast-based microbial fuel cells was investigated. The modification was conducted by depositing Co or Au thin layer with different thickness, 5 nm and 30 nm, using a sputtering technique. The electrode performance was evaluated by measuring the electrode potentials and the fuel cell power output. The Co modification significantly increased the performance of the fuel cell, while the Au modification inhibited the performance. SEM observation indicated that the adhesion density of the yeast cells on the electrode surface was affected by the metals. It was confirmed that the electron transfer took place through the surface confined species at the mediatorless anode.
Magnetic Separation of Organic Dyes in Wastewater Using Superconducting Bulk Magnets
Authors: Kondo Noriyo , Yokoyama Kazuya , Hosaka Sumio
Published: March 2013

We propose a magnetic separation system using superconducting bulk magnets to effectively separate organic dyes in wastewater. Two key technologies are applied in this system: magnetic seeding and magnetic separation. Magnetic activated carbons (MACs) are used to adsorb organic dyes Orange II and Crystal violet, which serve as magnetic seeds. We set up a magnetic separator by placing an acrylic pipe between the magnetic poles of a face-to-face superconducting bulk magnet for high gradient magnetic separation (HGMS) with the use of a stainless steel filter, composed of ferromagnetic wire stuffed into acrylic pipe. The experimental results show that the adsorption ratios of 99% and the separation ratios of over 97% were achieved at low flow rate for the organic dyes.
Crushing Behavior of SKYDEX® Material
Authors: Zhu Feng , Jiang Bin Hui , Yang King H. , Ruan Dong , Boczek Mike S. , Tannous Rabih
Published: March 2013

SKYDEX material is an advanced lightweight porous medium consisting of layers of periodic twin-hemispherical microstructures made of thermoplastic polyurethane. This material is used widely in personnel and structural protection. This paper reports a combined experimental and numerical study on crushing behavior of such material. Compression tests were conducted on the SKYDEX panels at the strain rates of 0.01~10 s-1. A 3D finite element model was developed and validated against experimental data. Based on the FE model, the deformation mode of the microstructures, strength, energy absorption, as well as strain rate effect were predicted and analyzed. Additional simulations were conducted to establish the relationship between the peak strength coefficient and relative density. SKYDEX® material has been found to be a competitive energy absorber among cellular solids.
Strain Rate Effect on Microstructure of Dynamically Compressed Magnesium Alloy AZ31B
Authors: Ahmad Iram Raza , Syfiqu Muhammad , Jing Xiao , Shu Dong W.
Published: March 2013

Lightweight materials have been in focus in recent times for their use in automobiles, planes and protective structures for numerous benefits ranging from reduction in fuel consumption and increased payload in vehicles to lighter and stronger protective structures. For efficient use of materials in applications where they are subjected to unusual higher sudden loads, it is necessary to understand their mechanical behaviour under such conditions.In present study, the effect of strain rate on deformation of magnesium alloy AZ31Bunder compression has been investigated. The alloy is subjected to various strain rates as 10-4s-1, 500s-1 and 2500s-1 and the microstructural analysis was performed to see the changes in the microstructure of the alloy and their effect on the mechanical response of the alloy is portrayed.
Plastic Deformation Clusters with High Kinetic Energy in Metallic Glass
Authors: Liu Wei Dong , Ruan H.H. , Zhang Liang Chi
Published: March 2013

Although localized atomic rearrangements have been considered to be the underlying mechanism of plastic deformation in metallic glass, the nucleation and evolution of such plasticity events are still elusive. With the aid of molecular dynamics analysis, this study revealed that a series of localized atomic rearrangement events would occur in metallic glass as demonstrated by the formation of high-kinetic-energy clusters. It was found that atomic clusters of average sizes of 1 to 2 nm nucleate during elastic deformation, and become prevailing after yielding. The cores of these clusters contain several high-velocity atoms, which drive the local structural change and accommodate plastic strain. The nucleation and evolution of the local plasticity events are shown clearly by the strong dynamic signature, attributed to the spontaneous structural reshuffling after crossing an energy barrier.
Effect of Intermetallic β-Mg17Al12 on Fracture of Ultralight Magnesium Alloy
Authors: Guan Ying Chun , Zhou Wei
Published: March 2013

An AZ91D magnesium alloy was tested in either compression or tension, and extensive observation of the tested samples was carefully carried out to understand the fracture initiation and propagation processes. Cracking of β-Mg17Al12 intermetallic compounds was found to occur easily in plastic zones under either compressive or tensile loading. However, the cracking did not necessarily result in fracture propagation. It is argued that the fracture is controlled by the microcrack propagation.
Localized Necking in a Round Tensile Bar with HCP Material Considering Tension-Compression Asymmetry in Plastic Flow
Authors: Yoon Jonghun , Cazacu Oana , Lee Jung Hwan
Published: March 2013

In spite of this progress in predicting ductile failure, the development of macroscopic yield criteria for describing damage evolution in HCP (hexagonal close-packed) materials remains a challenge. HCP materials display strength differential effects (i.e., different behavior in tension versus compression) in the plastic response due to twinning. Cazacu and Stewart [1] developed an analytic yield criterion for a porous material containing randomly distributed spherical voids in an isotropic, incompressible matrix that displays tension-compression asymmetry. The matrix material was taken to obey the isotropic form of the Cazacu et al. [2] yield criterion, which captures the tension-compression asymmetry of the matrix material. In this paper, finite element calculations of a round tensile bar are conducted with the material behavior described by the Cazacu and Stewart [1] yield criterion. The goal of these calculations is to investigate the effect of the tension-compression asymmetry on the necking induced by void evolution and propagation.
Cyclic Polycrystalline Viscoplastic Model for Ratchetting of a Body Centered Cubic Metal
Authors: Luo Juan , Kang Guo Zheng , Bruhns Otto T. , Zhang Chuan Zeng
Published: March 2013

In the framework of crystal plasticity, a new cyclic polycrystalline viscoplastic model is constructed to describe the uniaxial ratchetting of a body centered cubic (BCC) metal. At the intra-granular scale, a combined kinematic hardening rule similar to the Ohno-Abdel-Karim model is employed to address the ratchetting within each single crystal grain; and two sets of slip systems with different resistances to dislocation slip, i.e., primary and secondary ones, are considered to capture the physical nature of dislocation slips in a body centered cubic (BCC) metal. At the inter-granular scale, an explicit transition rule is adopted to extend the single crystal approach into a polycrystalline version. It is shown that the proposed model describes the uniaxial ratchetting of annealed 42CrMo steel, a body centered cubic (BCC) metal, reasonably. Also, it is seen that the crystal orientation influences significantly the ratchetting of body-centered cubic (BCC) single crystals.
Effect of Temperature-Dependent Properties on Cyclic Plasticity of Bond Coat in Thermal Barrier Systems
Authors: Su Luo Chuan , Li Jian Guo , Zhang Wei Xu , Wang Tie Jun
Published: March 2013

The accumulation of cyclic plasticity in bond coat (BC) is a key factor controlling the displacement instability of the thermally grown oxide (TGO) in thermal barrier systems. The cyclic plasticity is affected by the component material properties, which vary observably with the service temperature. A numerical model with the behavior of creep and thermal growth in TGO under thermal cycling is used to explore the effect of temperature-dependent properties on cyclic plasticity in BC. The influence of temperature-dependent Young's modulus of thermal barrier coating (TBC), TGO, BC and substrate, thermal expansion coefficient of TBC, BC and substrate, and the yield strength of BC on cyclic plasticity in BC is discussed respectively.
On the Cyclc Behavior of 304L and 316L Stainless Steels
Authors: Taleb Lakhdar
Published: March 2013

This work is devoted to a survey of the ratcheting phenomenon and follows the study presented in [1]. Two current austenitic stainless steels 304L and 316L are considered and tested under cyclic stress and strain control at 350°C. Under stress control ratcheting seems very small under proportional as well as non-proportional stress control. The elastic shakedown steady state exhibited by both materials may be explained by their capabilities to develop very significant cyclic hardening (especially isotropic) at 350°C.
Propagation Behavior of Main Crack in Reinforced Concrete Beams Strengthened with CFRP under Cyclic Bending Load
Authors: Li Zheng Wei , Huang Pei Yan , Zhou Hao
Published: March 2013

Fatigue behavior of reinforced concrete (RC) beam can be improved by externally bonded fiber reinforced polymer (FRP). However, propagation behavior of a crack on the RC beam will have serious effect on the fatigue life of the beam strengthened with FRP. In this paper, a finite element (FE) procedure was developed to analysis the stress intensity factor (SIF) of the main crack and an experimental study was conducted to investigate the propagation rate of the main crack of the RC beam strengthened with carbon fiber laminate (CFL) under cyclic bending load. The FE analysis results show that the SIF near the main crack tip increases at the beginning and then decreases with the fatigue crack propagation. When relative crack length α is equal to 0.3, the SIF is maximum. When α approaches 0.75, the SIF approaches zero. A total of 3 RC beams strengthened with CFL were tested. The experimental results show that it is possible to divide the process of the crack propagation into three distinct phases, including crack initiation and then quickly propagation, stable propagation and then rest and unstable propagation. A semi-empirical equation based on the Paris Law was developed to predict the crack propagation rate.
Indentation Behavior of a Closed-Cell Aluminum Foam at Elevated Temperatures
Authors: Li Zhi Bin , Zheng Zhi Jun , Yu Ji Lin
Published: March 2013

A series of deep indentation and uniaxial compression tests of closed-cell aluminum foams at room temperature as well as elevated temperatures were conducted. A flat-ended punch (FEP) was used in the indentation tests. Cross-sectional views of the specimens after tests show that the deformation is roughly confined to the material directly underneath the indenter with slightly lateral spread. It is found that plastic collapse strength and energy absorption of the specimens are temperature dependent in both loading conditions. Tear energy of the foam in FEP indentation depends on the indentation depth and temperature.
Application of Indentation Size Effect in Finite Element Analysis for Friction Simulation
Authors: Taureza Muhammad , Castagne Sylvie , Lim Samuel Chao Voon
Published: March 2013

Contact simulation involving asperities was developed by assuming that the deformation by asperities is equivalent to the deformation by an indenter in a hardness test. Consequently, depth dependent flow stress curves were derived from the indentation size effect model from Abu Al-Rub and were used to simulate the influence of the number of asperities involved during contact on the distribution of contact pressure and the value of effective friction coefficient. Results from simulations suggested that multiplying the number of asperities in contact, when the size of the asperities is comparable to the size of the apparent contact, is not followed by proportional multiplication of the reaction forces. The competing phenomena observed in the simulation are then proposed as an explanation to friction size effect occurring in microforming.
Contact Pressure Dependent Frictional Characteristics of Hot-Dip Galvanized High Strength Steel Sheet and its Effect on Springback Behavior
Authors: Han Soo Sik
Published: March 2013

The application of high strength steel sheet on stamping part extends the range of contact pressure than that of mild steel’s and makes the effect of contact pressure on frictional characteristics of steel sheet a regardable fact. The friction test with hot-dip galvanized high strength steel sheet was conducted under various contact pressures, to investigate the influence of contact pressure on frictional behavior of steel sheet. According to the test result, the contact pressure effect on friction is considerable. The friction between tool and work-piece influences the stress distribution during stamping process. To investigate the influence of frictional behavior on stress distribution at stamped part, the U-draw bending under constant blank holding force with different blank size were conducted and it was verified by finite element analysis with and without considering contact pressure effect on frictional behavior. As the result of study, the variation of frictional behavior depending on contact pressure results changes in the stress distribution of parts that has effects on tendency of springback for high strength steel sheet stamping.