bluuebunny/crossref_metadata_2025 huggingface dataset:
Proposal of Extended Boundary Integral Equation Method for Rupture Dynamics Interacting With Medium Interfaces
Authors: Kame Nobuki , Kusakabe Tetsuya
Published: March 2012

The boundary integral equation method (BIEM) has been applied to the analysis of rupture propagation of nonplanar faults in an unbounded homogeneous elastic medium. Here, we propose an extended BIEM (XBIEM) that is applicable in an inhomogeneous bounded medium consisting of homogeneous sub-regions. In the formulation of the XBIEM, the interfaces of the sub-regions are regarded as extended boundaries upon which boundary integral equations are additionally derived. This has been originally known as a multiregion approach in the analysis of seismic wave propagation in the frequency domain and it is employed here for rupture dynamics interacting with medium interfaces in time domain. All of the boundary integral equations are fully coupled by imposing boundary conditions on the extended boundaries and then numerically solved after spatiotemporal discretization. This paper gives the explicit expressions of discretized stress kernels for anti-plane nonplanar problems and the numerical method for the implementation of the XBIEM, which are validated in two representative planar fault problems.
Prediction of Ductile Fracture Surface Roughness Scaling
Authors: Needleman Alan , Tvergaard Viggo , Bouchaud Elisabeth
Published: March 2012

Experimental observations have shown that the roughness of fracture surfaces exhibit certain characteristic scaling properties. Here, calculations are carried out to explore the extent to which a ductile damage/fracture constitutive relation can be used to model fracture surface roughness scaling. Ductile crack growth in a thin strip under mode I, overall plane strain, small scale yielding conditions is analyzed. Although overall plane strain loading conditions are prescribed, full 3D analyses are carried out to permit modeling of the three dimensional material microstructure and of the resulting three dimensional stress and deformation states that develop in the fracture process region. An elastic-viscoplastic constitutive relation for a progressively cavitating plastic solid is used to model the material. Two populations of second phase particles are represented: large inclusions with low strength, which result in large voids near the crack tip at an early stage, and small second phase particles, which require large strains before cavities nucleate. The larger inclusions are represented discretely and various three dimensional distributions of the larger particles are considered. The scaling properties of the predicted thickness average fracture surfaces are calculated and the results are discussed in light of experimental observations.
Guided Waves Along Fluid-Filled Cracks in Elastic Solids and Instability at High Flow Rates
Authors: Dunham Eric M. , Ogden Darcy E.
Published: March 2012

We characterize wave propagation along an infinitely long crack or conduit in an elastic solid containing a compressible, viscous fluid. Fluid flow is described by quasi-one-dimensional mass and momentum balance equations with a barotropic equation of state, and the wall shear stress is written as a general function of width-averaged velocity, density, and conduit width. Our analysis focuses on small perturbations about steady flow, through a constant width conduit, at an unperturbed velocity determined by balancing the pressure gradient with drag from the walls. Short wavelength disturbances propagate relative to the fluid as sound waves with negligible changes in conduit width. The elastic walls become more compliant at longer wavelengths since strains induced by opening or closing the conduit are smaller, and the fluid compressibility becomes negligible. As wavelength increases, the sound waves transition to crack waves propagating relative to the fluid at a slower phase velocity that is inversely proportional to the square-root of wavelength. Associated with the waves are density, velocity, pressure, and width perturbations that alter drag. At sufficiently fast flow rates, crack waves propagating in the flow direction are destabilized when drag reduction from opening the conduit exceeds the increase in drag from increased fluid velocity. This instability may explain the occurrence of self-excited oscillations in fluid-filled cracks.
A Linearized Model for Lithium Ion Batteries and Maps for their Performance and Failure
Authors: Purkayastha Rajlakshmi , McMeeking Robert M.
Published: March 2012

A linearized model is developed for lithium ion batteries, relying on simplified characterizations of lithium transport in the electrolyte and through the interface between the electrolyte and the storage particles of the electrodes. The model is valid as a good approximation to the behavior of the battery when it operates near equilibrium, and can be used for both discharge and charging of the battery. The rate of extraction of lithium from and to the electrode storage particles can be estimated from the results of the model, information that can be used in turn to estimate the shrinkage and swelling stresses that develop in the particles. Given specified rates of extraction for spherical particles, maps of the resulting shrinkage and swelling stresses can be developed connecting their values to battery parameters such as particles size, diffusion coefficient, lithium partial molar volume, and particle elastic properties. Since a constant rate of extraction can only be achieved for a limited period of time until the concentration of lithium at the particle perimeter constrains the lithium mass transport, plots of the average state of charge in the particle versus time are also produced.
On Averaging Interface Response During Dynamic Rupture and Energy Partitioning Diagrams for Earthquakes
Authors: Noda Hiroyuki , Lapusta Nadia
Published: March 2012

Earthquakes occur as dynamic shear cracks and convert part of the elastic strain energy into radiated and dissipated energy. Local evolution of shear strength that governs this process, which is variable in space and time, can be studied from laboratory experiments and rupture models. At the same time, increasingly accurate measurements of radiated energy and other quantities characterize earthquakes in a rupture-averaged way. Here, we present and study two approaches to averaging frictional dissipation during dynamic rupture. The first one is based on the actual progression of dissipation, but the associated averaged shear stress does not reflect the local friction behavior. The second one is constructed to preserve prevailing features of local stress-slip response and performs well in the examples studied. The developed approach should be useful for visualizing energy partitioning in dynamic models and linking them to observations using diagrams that reflect dominant features of local stress evolution.
Kinematic Shakedown Analysis of Anisotropic Heterogeneous Materials: A Homogenization Approach
Authors: Li H. X.
Published: March 2012

A nonlinear mathematical programming approach together with the finite element method and homogenization technique is developed to implement kinematic shakedown analysis for a microstructure under cyclic/repeated loading. The macroscopic shakedown limit of a heterogeneous material with anisotropic constituents is directly calculated. First, by means of the homogenization theory, the classical kinematic theorem of shakedown analysis is generalized to incorporate the microstructure representative volume element (RVE) chosen from a periodic heterogeneous or composite material. Then, a general yield function is directly introduced into shakedown analysis and a purely kinematic formulation is obtained for determination of the plastic dissipation power. Based on the mathematical programming technique, kinematic shakedown analysis of an anisotropic microstructure is finally formulated as a nonlinear programming problem subject to only a few equality constraints, which is solved by a generalized direct iterative algorithm. Both anisotropy and pressure dependence of material yielding behavior are considered in the general form of kinematic shakedown analysis. The purely kinematic approach based on the kinematic shakedown analysis has the advantage of less computational effort on field variables and more convenience for displacement-based finite element implementation. The developed method provides a direct approach for determining the reduced macroscopic strength domain of anisotropic heterogeneous or composite materials due to cyclic or repeated loading.
The Analytical Solutions of Incompressible Saturated Poroelastic Circular Mindlin’s Plate
Authors: Wen P. H.
Published: March 2012

In this paper the fundamental solutions for an infinite poroelastic moderately thick plate and analytical solutions for a circular plate saturated by a incompressible fluid are derived in the Laplace transform domain. In order to obtain the solutions in the time domain, the Durbin’s Laplace transform inverse method has been used with high accuracy. The formulations using the boundary integral equation method can be derived directly with these fundamental solutions. In addition, the analytical solutions for a circular plate can be used to validate the accuracy of numerical algorithms such as the boundary element method and the method of fundamental solution. The deflection, moment, and equivalent moment in the time domain for a circular plate, subjected to uniform load and a concentrated force are presented, respectively. The analytical solutions demonstrate that interaction between the solid and flow is significant.
A Model of Force Generation in a Three-Dimensional Toroidal Cluster of Cells
Authors: Nurse Asha , Freund L. B. , Youssef Jacquelyn
Published: March 2012

Observation of the self-assembly of clusters of cells in three dimensions has raised questions about the forces that drive changes in the shape of the cell clusters. Cells that self-assemble into a toroidal cluster about the base of a conical pillar have been observed in the laboratory to spontaneously climb the conical pillar. Assuming that cell cluster reorganization is due solely to surface diffusion, a mathematical model based on the thermodynamics of an isothermal dissipative system is presented. The model shows that the cluster can reduce its surface area by climbing the conical pillar, however, this is at the expense of increasing its gravitational potential energy. As a result, the kinetics of the climb are affected by parameters that influence this energy competition, such as the slope of the conical pillar and a parameter of the model κ that represents the influence of the surface energy of the cluster relative to its gravitational potential energy.
Exact Matching Condition at a Joint of Thin-Walled Box Beams Under Out-of-Plane Bending and Torsion
Authors: Choi Soomin , Jang Gang-Won , Young Kim Yoon
Published: March 2012

To take into account the flexibility resulting from sectional deformations of a thin-walled box beam, higher-order beam theories considering warping and distortional degrees of freedom (DOF) in addition to the Timoshenko kinematic degrees have been developed. The objective of this study is to derive the exact matching condition consistent with a 5-DOF higher-order beam theory at a joint of thin-walled box beams under out-of-plane bending and torsion. Here we use bending deflection, bending/shear rotation, torsional rotation, warping, and distortion as the kinematic variables. Because the theory involves warping and distortion that do not produce any force/moment resultant, the joint matching condition cannot be obtained just by using the typical three equilibrium conditions. This difficulty poses considerable challenges because all elements of the 5×5 transformation matrix relating the field variables of one beam to those in another beam should be determined. The main contributions of the investigation are to propose additional necessary conditions to determine the matrix and to derive it exactly. The validity of the derived joint matching transformation matrix is demonstrated by showing good agreement between the shell finite element results and those obtained by the present box beam analysis in various angle box beams.
Statistical Knockdown Factors of Buckling Anisotropic Cylinders Under Axial Compression
Authors: Takano Atsushi
Published: March 2012

Statistical knockdown factors for the axial buckling of anisotropic cylinders were derived for practical design purposes. The solution with the least amount of simplification in the linear bifurcation theory was chosen from the previously published solutions, and it was compared with more than 100 experimental results from the open literature. A-basis values (99% probability with 95% confidence level) and B-basis values (90% probability with 95% confidence level) of knockdown factors were obtained by using inferential statistics, i.e., inference concerning unknown aspects of a population by using a small sample.
A Double Degree Freedom Mass-Spring-Damper-Foam Collision Model for High Porosity Metallic Foams
Authors: Li Binchao , Zhao Guiping , Jian Lu Tian
Published: March 2012

A theoretical study on the vibration isolation and energy absorption capability of high porosity closed-cell aluminum foams subjected to impact loading is presented. A double degree of freedom (DDF) spring-damper-foam collision model (mimicking important equipment and/or personnel) is established to explore the physical mechanisms of shock attenuation when the system as a whole is dropped from a given height and collides with hard ground. For validation, the finite element method is employed to simulate directly the dynamic responses of the whole system. The effects of key system parameters including spring stiffness, damping ratio, mass ratio, initial impact velocity and foam thickness on the mass of the foam cushion and peak acceleration of the protected structure are quantified. The DDF model is subsequently employed to minimize the weight of the foam cushion against impact energy subjected to different design constraints; the corresponding optimal geometrical dimensions of the foam cushion are also obtained.
Specialization and Rarity Predict Nonrandom Loss of Interactions from Mutualist Networks
Authors: Aizen Marcelo A. , Sabatino Malena , Tylianakis Jason M.
Published: March 2012

Untangling the Web

Interspecific interactions link species within complex trophic and nontrophic webs (see the Perspective by

Lewinsohn and Cagnolo

). Theoretical work has suggested that certain characteristics of species, or even interactions, may predispose them to extinction from a network.

Aizen
et al.

(p.
1486
) provide empirical evidence that plant-pollinator interactions are lost nonrandomly following habitat reduction in isolated hills in the Argentine pampas. Some types of interaction were more vulnerable to disruption than others, particularly when the specialization of the interacting was high and when the interactions were infrequent.

Stouffer
et al.

(p.
1489
) applied network theory to predict the dynamical importance of species across different food webs. Characteristic three-node motifs were identified, and species were characterized according to the relative frequencies with which they occupied unique positions within the motifs. These relative frequencies and the dynamic importance of the motifs were then used to identify a species-level importance within a food web.
The Gutenberg Discontinuity: Melt at the Lithosphere-Asthenosphere Boundary
Authors: Schmerr Nicholas
Published: March 2012

The Thin Melt Line

Pronounced and persistent variations in the speed of seismic waves as they travel through Earth's interior imply the presence of a physical or chemical boundary layer. Near the lithosphere-asthenosphere boundary, these seismic discontinuities are often patchy and their origins are disputed. By analyzing a set of short-period seismic waves across the Pacific Ocean,
Schmerr
(p.
1480
; see the Perspective by

Kawakatsu

) relates the intermittency of this seismic discontinuity to a layer of partial melt below the oceanic lithosphere. The melt may arise from a number of geodynamic processes, including upwellings from the mantle at hot spots like Hawaii, or small-scale thermal convection in the mantle.
The Hunters Did It
Authors: McGlone Matt
Published: March 2012

Human hunting was responsible for the extinction of large mammal species in tropical Australia.
Oscar Miller (1925–2012)
Authors: McKnight Steven , Beyer Ann , Gall Joseph
Published: March 2012

An unconventional molecular biologist used the electron microscope to take snapshots of active genes.
Old Drug, New Hope for Alzheimer's Disease
Authors: Strittmatter Warren J.
Published: March 2012

A nuclear receptor agonist increases the clearance of beta-amyloid and improves cognitive skills in a mouse model of Alzheimer's disease.
The Imaginary Mind of a Mouse
Authors: Morris Richard G. M. , Takeuchi Tomonori
Published: March 2012

Can the brain combine a previous memory into a current situation, creating the memory of an imaginary experience?
New Light on a Continuing Clash
American Genesis
The Antievolution Controversies from Scopes to Creation Science

by Jeffrey P. Moran

Oxford University Press, Oxford, 2012. 212 pp. $29.95, £19.99. ISBN 9780195183498.
Authors: Burnett Thomas
Published: March 2012

Examining how issues of race, gender, and regional identity affected responses to the teaching of evolution, Moran offers a fresh perspective on 20th-century clashes between science and religion in the United States.
LIGHT-PARTICLE EMISSION FROM FISSIONING HOT ROTATING NUCLEI
Authors: BARTEL JOHANN , POMORSKI KRZYSZTOF , NERLO-POMORSKA BOŻENA
Published: March 2012

The decay process of hot and rotating compound nuclei is studied. In particular the competition between fission and n, p and α-particle emission is discussed. The nuclear fission process is described by a Langevin equation coupled to Master equations for particle evaporation. Light particle emission rates obtained with the Weisskopf theory and the semiclassical phase-space distribution-function approach are compared. Coulomb barriers for the emission of charged particles are studied.
SYMMETRY RESTORATION FOR ODD-MASS NUCLEI WITH A SKYRME ENERGY DENSITY FUNCTIONAL
Authors: BALLY B. , AVEZ B. , BENDER M. , HEENEN P.-H.
Published: March 2012

In these proceedings, we report first results for particle-number and angular-momentum projection of self-consistently blocked triaxial one-quasiparticle HFB states for the description of odd-A nuclei in the context of regularized multi-reference energy density functionals, using the entire model space of occupied single-particle states. The SIII parametrization of the Skyrme energy functional and a volume-type pairing interaction are used.
Diversity, isomer composition, and design of combinatorial libraries of tetrapyrrole macrocycles
Authors: Taniguchi Masahiko , Lindsey Jonathan S.
Published: March 2012

Combinatorial libraries of substituted tetrapyrrole macrocycles, which can now be prepared via a variety of approaches, typically are rich in isomers. Terminology for describing such isomers (due to distinct patterns of peripheral substituents) is delineated in several illustrative examples. A hierarchical relationship exists of molecular formula, condensed formula(s) of substituents, set(s) of pyrrole collocates (conveying each pair of β-pyrrolic substituents), and isomers of substituted tetrapyrrole macrocycles. Isomers with identical pyrrole collocate sets can arise owing to distinct positions or orientations of the (homo- or hetero-substituted) pyrrolic units in a macrocycle. Consideration of a handful of virtual combinatorial libraries illustrates tradeoffs of library size, chemical richness, and isomeric content. As one example, octa-derivatization of a tetrapyrrole scaffold with eight reactants A–H affords 2,099,728 members (99.7% isomers, 82,251 pyrrole collocate sets, and 6,435 condensed formulas) whereas the reversible self-condensation of four pyrroles that bear the same eight entities (AB, CD, EF, GH) affords 538 members (93.5% isomers, 35 pyrrole collocate sets, and 35 condensed formulas). Derivatization affords all combinations and permutations whereas self-condensation of substituted pyrroles carries collocational restrictions. Understanding such tradeoffs and the structural origin of isomerism are important aspects in the design of tetrapyrrole combinatorial libraries.
SURVIVAL TRENDS IN CHILDHOOD HEMATOLOGICAL MALIGNANCIES
Authors: RICH STEPHANIE , ALI SHIHAB , CALKINS GEOFFREY W. , MICHAELSON JAMES S.
Published: March 2012

Survival of patients with childhood hematological malignancies has increased markedly in the past decades. To examine the fine-scale details of how this progress has occurred, we carried out Kaplan–Meier cause-specific survival analysis using the Surveillance Epidemiology and End Results (SEER) dataset for patients with childhood hematological malignancies — Hodgkin's Lymphoma, Non-Hodgkin's Lymphoma, Lymphoblastic Leukemia and Myeloid Leukemia — diagnosed in five eras: 1983–1987; 1988–1992; 1993–1997; 1998–2002 and 2003–2007. We generated Kaplan–Meier estimates of survival for each of the first 24 years after diagnosis. These figures agree with previously reported five- and ten-year values and attest to the remarkable increase in survival that has occurred over the past three decades of medical progress. The trend towards progressively increasing survival shows no sign of slowing, suggesting that we may expect further increases in survival in the years ahead. Most of the increase in survival for childhood hematological malignancies has occurred by reducing the risk of death in the first two years after diagnosis. This may be largely explained by the fact that this is the time period when patients are at highest risk of death.
LARGE-SCALE FIRST PRINCIPLES CONFIGURATION INTERACTION CALCULATIONS OF OPTICAL ABSORPTION IN BORON CLUSTERS
Authors: SHINDE RAVINDRA , SHUKLA ALOK
Published: March 2012

We have performed systematic large-scale all-electron correlated calculations on boron clusters B n(n = 2 - 5), to study their linear optical absorption spectra. Several possible isomers of each cluster were considered, and their geometries were optimized at the coupled-cluster singles doubles (CCSD) level of theory. Using the optimized ground-state geometries, the excited states of different clusters were computed using the multi-reference singles-doubles configuration–interaction (MRSDCI) approach, which includes electron correlation effects at a sophisticated level. These CI wave functions were used to compute the transition dipole matrix elements connecting the ground and various excited states of different clusters, eventually leading to their linear absorption spectra. The convergence of our results with respect to the basis sets, and the size of the CI expansion were carefully examined. The contribution of configurations to many body wave-function of various excited states suggests that the excitations involved are collective, plasmonic type.
ELECTRIC-FIELD-INDUCED CRACK GROWTH AT ELECTRODE EDGE IN PIEZOELECTRIC CERAMICS
Authors: KUSUKAWA KAZUHIRO
Published: March 2012

Small crack growth behavior in poled lead zirconate titanate was examined under cyclic electric loading. A crack located at the edge of a partial electrode grew along the electrode boundary during the loading. The crack growth rate decreased with increasing crack length until a non-propagating crack was reached. The growth rate and crack length of the non-propagating crack were affected by the amplitude and bias levels of the electric loading. In the case of high-amplitude loading or negative-biased loading, the crack growth rate varied considerably because of domain switching. Finite element analysis of a three-dimensional permeable crack showed that the mode III stress intensity factor range is independent of crack length, but it decreases as a result of the frictional force of a positive electric field. Fracture surface observations showed that intergranular cracking is dominant near the tip of the non-propagating crack.
ELECTROLUMINESCENCE OBSERVATION OF MICROCRACK GROWTH BEHAVIOR OF CRYSTALLINE SILICON SOLAR MODULES FABRICATED BY HOT-AIR SOLDERING TECHNOLOGY
Authors: LIN KEH-MOH , LEE YANG-HSIEN , WANG LI-KUO , CHEN LI-WEI , YANG SIAN-YI , CHEN YI-CHIA , LIU DE-CHIH , HUANG MING-YUAN , WU ZHEN-CHENG , CHEN CHIEN-PIN
Published: March 2012

In this study, the quality degradation of Si -based photovoltaic (PV) modules during the aging process was observed by using electroluminescent (EL) technology and was verified by the IV curve measurements in order to find out the occurring timing of damages on solar cells. Furthermore, the influences of solder materials and soldering temperatures on the performance of the PV modules were also studied. Experiment results show that, high soldering temperatures which induce high thermal stress can easily lead to the power loss of the PV modules. Besides, the mechanical properties of the solar cells itself can also affect the degradation rate of the PV modules. On PV modules soldered with SnPb (SP) solder, more than 80% of cell damages occurred during the soldering and encapsulation processes. When SnAgPb (SAP) solder was used, a small part of the cell damages didn't emerge until the initial stage of the thermal cycling test (TC.) This phenomenon is attributed to the reduction of residual stress between the ribbon and the silver paste because of the good wettability of SAP solder.
DYNAMIC CRACK PROPAGATION IN A FUNCTIONALLY GRADED PIEZOELECTRIC INTERFACE LAYER BETWEEN TWO DISSIMILAR PIEZOELECTRIC LAYERS UNDER ELECTROMECHANICAL LOADING
Authors: SHIN JEONG WOO , LEE YOUNG-SHIN
Published: March 2012

The dynamic propagation of a crack in a functionally graded piezoelectric material (FGPM) interface layer between two dissimilar piezoelectric layers under anti-plane shear is analyzed using the integral transform approaches. The properties of the FGPM layers vary continuously along the thickness. FGPM layer and the two homogeneous piezoelectric layers are connected weak-discontinuously. A constant velocity Yoffe-type moving crack is considered. Numerical values on the dynamic energy release rate (DERR) are presented for the FGPM. Followings are helpful to increase of the resistance of the crack propagation of the FGPM interface layer: (a) certain direction and magnitude of the electric loading; (b) increase of the thickness of the FGPM interface layer; (c) increase of the thickness of the homogeneous piezoelectric layer which has larger material properties than those of the crack plane in the FGPM interface layer. The DERR always increases with the increase of crack moving velocity and the gradient of the material properties.
ABSORBING PROPERTIES AND OPTIMIZATION OF Ni POWDER/M-GLASS FIBER REINFORCED EPOXY COMPOSITE PANELS
Authors: LI XIAOMIN , ZHU ZHENGHOU , SONG HUI , XU XUEJIAO , LIU ZHIBIN
Published: March 2012

In this paper, Ni powder/M-glass fiber reinforced epoxy composite panels with different Ni powders were prepared by mould pressing method, of which the ultrafine Ni powder is prepared by the liquid reduction method. The waveguide method can be used to measure the electromagnetic parameters of the samples in the frequency ranged from 8.2 GHz to 18 GHz. The results show that Ni powders distributed evenly during the M-glass fibers reinforced epoxy layers. The main absorbing mechanism of composite panels is magnetic loss. The absorbing properties of samples increase with the adding of Ni powder contents and the thickness of panels. Based on the theory of the transmission line, the optimization design of Ni powder/ M-glass fiber reinforced epoxy composite has been calculated. When the whole thickness of the composite panels is 4.6mm excepting the Al plate thickness with the absorbing layer of Ni powder/ M-glass fiber reinforced epoxy of 1mm, the whole absorbing properties improve gradually with the increase of frequency ranged from 8.2 GHz to 18GHz and the absolute value of the reflection coefficient R is above 10dB.
VARIATION OF ELECTRIC PROPERTIES BETWEEN SURFACE PERMANENT MAGNET AND INTERIOR PERMANENT MAGNET MOTOR
Authors: WOO BYUNG-CHUL , HONG DO-KWAN , LEE JI-YOUNG
Published: March 2012

The most distinctive advantage of transverse flux motor(TFM) is high torque density which has prompted many researches into studying various design variants. TFM is well suited for low speed direct drive applications due to its high torque density. This paper deals with simulation based comparisons between a surface permanent magnet transverse flux motor(SPM-TFM) and an interior permanent magnet transverse flux motor(IPM-TFM). A commercial finite element analysis(FEA) software Maxwell 3D is used for electromagnetic field computation to fully analyze complex geometry of the TFMs. General characteristics, such as cogging torque, rated torque and torque ripple characteristics of the two TFMs are analyzed and compared by extensive 3D FEA.
DIRECT OXIDATION OF TRYPTOPHAN ON MULTI-WALL CARBON NANOTUBES MODIFIED CARBON ELECTRODE AND ITS APPLICATION TO FUEL CELL
Authors: YABUTANI TOMOKI , SHODA YOSHIO , TANI YUJI , YAMADA YOHEI , MOTONAKA JUNKO
Published: March 2012

Direct oxidation of tryptophan on multi-wall carbon nanotubes modified glassy carbon electrode was examined. Surface poisoning, which was suppression of oxidative current caused from adsorption of oxidized compounds of amino acids through multiple redox scan, was observed on carbon material electrodes (multi-wall carbon nano tube(CNT), carbon powder(CP), Ketjen Black (KB) and glassy carbon(GC). It was found that CNT showed a highly inhibitory effect on the surface poisoning and high current value in the direct oxidation of tryptophan because of a π-π interaction between CNT and indole ring of tryptophan results from orbital mixing. This CNT modified GC electrode was applied to an anode in a fuel cell used with amino acids as fuel. As a result, the maximum of the power density showed 0.36 mW cm-2 at 2.5 mA cm-2 of the current density and 140 mV of the cell voltage.
A FINE-TURNING COPOLYMER BASED ON TRIPHENYLAMINE AND 3,4-ETHYLENEDIOXYTHIOPHENE VIA ELECTROCHEMICAL POLYMERIZATION
Authors: OUYANG MI , HU BIN , ZHANG CHENG
Published: March 2012

Copolymer based on triphenylamine (TPA) and 3,4-ethylenedioxythiophene (EDOT) is polymerized electrochemically. The structure, morphology and electrochemical properties of the obtained copolymer are investigated by cyclic voltammetry and FT-IR spectroscopy. The results confirm the copolymerization of TPA/EDOT. UV-vis spectra show that the absorption peaks of the copolymer are different from those of Polytriphenylamine. Moreover, photoluminescence spectra of the copolymer exhibit great changes in emission color from pale blue to pale green with the variety of ratio of two monomers. Therefore, the monomer feed ratio plays important roles in the optical property of this copolymer.
PREPARATION OF AN ELECTRODE MODIFIED WITH A THERMOSTABLE ENZYME BACILLUS SUBTILIS COTA BY ELECTRODEPOSITION
Authors: WATANABE TOSHIO , YAMADA YOHEI , MOTONAKA JUNKO , YABUTANI TOMOKI , SAKURABA HARUHIKO , YASUZAWA MIKITO
Published: March 2012

In this study, electrodeposition of thermostable enzyme Bacillus subtilis CotA, which is a laccase and has a bilirubin oxidase (BOD) activity, was investigated. The electrodeposition was operated in a mixture of Bacillus subtilis CotA in the PBS (pH 8.0) and TritonX-100 under applying potential (1100 mV vs. Ag/AgCl for 5 min.). The current response was measured by linear sweep voltammetry technique (LSV). The thermostable enzyme Bacillus subtilis CotA electrodeposited electrode was compared with a mesophile BOD electrodeposited electrode. As a result, the Bacillus subtilis CotA modified electrode showed better sensitivity and long-term stability than the mesophile BOD modified electrode.
ELUTION BEHAVIOR OF PHOSPHATE CONTAINED IN Mg/Fe AND Zn/Fe LAYERED DOUBLE HYDROXIDES
Authors: Kurashina Masashi , Amatsu Tomohiro , Ochi Takaaki , Ohigashi Nozomi , Kanezaki Eiji
Published: March 2012

Layered double hydroxide (LDH) is a layered hydroxide and exchangeable anion is intercalated in its interlayer. Application of the LDH as a controlled-release material of interlayer anions has become of interest, thus it is important to clarify the elution behavior of interlayer anions. We synthesized hydrogenphosphate-intercalated Mg / Fe and Zn / Fe LDH and elution of phosphate from these LDH were tested in deionized water, sodium chloride solution, sodium sulfate solution, and sodium carbonate solution. For Mg / Fe LDH, the amount of eluted phosphate increased with time and reached to maximum that increased as higher concentrate solution was used. The elution of phosphate from Mg / Fe LDH could be described by the pseudo second-order equation. This elution behavior was explained as ion-exchange reaction of phosphate with sulfate or carbonate in tested solution by means of kinetic simulation using Runge-Kutta method. In the eluted solution, metal ions contained in the LDH were detected and its amount depended on pH of the tested solution, that is, amounts of eluted Mg and Zn ions were small at higher pH (ca. 10) for Mg / Fe and Zn / Fe LDH respectively, but large amount of Zn ion was detected when 2.03 mol·l-1 carbonate solution (pH = 13) was used. Thus elution of phosphate was caused by two main reactions: ion exchange and decomposition of the LDH.
SYNTHESIS AND CHARACTERIZATION OF LUMINOL PERSULPHATE CHEMILUMINESCENCE IN AQUEOUS AMINES
Authors: RAUT V. M. , MORE P. S. , KHOLLAM Y. B. , SONONE R. S. , KONDAWAR S. B. , KOINKAR PANKAJ
Published: March 2012

The chemiluminescence (CL) emission spectra of luminol were recorded using Fuss spectrograph in different aqueous aliphatic amines using sodium persulphate alone and mixture with hydrogen peroxide as an oxidant. The CL emission spectra after resolution showed two emission bands at 425 and 455 nm. The CL mechanism was explained on the basis of two exited state species formed during oxidation of luminol. The CL of luminol is found to be very weak as persulphate slowly produced oxygen. The glow become intense with time as more and more oxygen is made available for oxidation of luminol. The mixture of hydrogen peroxide and sodium persulphate is found to be more effective in producing intense and long lived CL glow for luminol. The CL emission band of luminol by using sodium persulphate and mixture with hydrogen peroxide is explained on the basis of formation of exited singlet and triplet state of 3-aminophthalate ion (3-APA). The shorter wavelength emission band of 425 nm is found to be very weak in intensity as compared to longer wavelength emission band of 455 nm. Thus phosphoresce is favored in case of persulphate CL of luminol.
SURFACE REPLICATION OF MOLDED PRODUCTS WITH MICRONEEDLE FEATURES IN INJECTION MOLDING
Authors: UCHIUMI KAZUYASU , TAKAYAMA TETSUO , ITO HIROSHI , INOU AKINORI
Published: March 2012

Micro-molding of microneedle features was conducted using several injection-molding techniques. Injection compression molding and injection molding were performed with supercritical carbon dioxide fluid and with or without vacuum processing inside the mold cavity. Effects of process parameters on processability and surface replication of the molded parts were evaluated. The height replication ratio for microneedles was improved using injection compression molding. At a shorter compression stroke, the needle height was improved, and the influence of compression delay time was also small. Moreover, the effects of vacuum processing inside the mold cavity under the filling process were slight. The height replication ratio for microneedles showed the highest values using injection molding using supercritical carbon dioxide fluid with vacuum inside the mold cavity.
PRESSURE-INDUCED CRACK PROPAGATION BEHAVIOR IN A PARTICLE-REINFORCED COMPOSITE
Authors: HA JAE-SEOK , KIM JAE-HOON
Published: March 2012

An experimental investigation was conducted to study pressure-induced crack propagation behavior of a particle-reinforced composite (PRC) under various pressurization rate conditions. A pre-cracked specimen of a metallic particle-reinforced rubbery composite was fixed in a holder which is installed in a windowed test chamber, and then high compressed nitrogen gas rapidly pressurized the chamber and the specimen. Chamber pressures were measured during the test, and detailed sequences of crack initiation and propagation were recorded by a high-speed digital video camera. Pressure vs. time traces were obtained from test results, and pressurization rates were defined from them. The crack propagation contours and lengths under various pressurization rates were observed through a stereoscopic microscope. Also, a progression of the crack initiation and propagation was observed by the sequences of the crack recorded by the high-speed digital video camera.
DEVELOPMENT OF READY-MIXED SHOTCRETE FOR IMPROVEMENT OF CONSTRUCTION QUALITY IN KOREA
Authors: KIM DONG-MIN , MA SANG-JOON , KANG EUN-GU
Published: March 2012

Ready-mixed shotcrete is dry-mixed at the plant before delivering to the site for pouring, making it possible the accurate aggregate quality control and improved construction quality thanks to standardized material. In this study, maximum size of the coarse aggregate for ready-mixed shotcrete was determined and the problem of material segregation at the production process at the plant could be solved through pilot plant test. Furthermore, comparison in quality with existing field mixing method was carried out through field application evaluation.
AN INVESTIGATION OF FATIGUE PROPERTIES OF PRE-QUENCHED-TEMPERED S45C STEEL WITH PLASMA NITRIDING TREATMENT
Authors: Wu Bo , Zhang Jianxun , Murakami Ri-ichi
Published: March 2012

Quenched and tempered (QT) S45C steel was processed by plasma nitriding (a mixture of 40% N 2-60% H 2, 400 Pa , 773 K ) with two different durations: 8 h and 48 h. The microhardness, surface residual stress and nitriding layer compound were separately detected and the effect was discussed with the fatigue test result. The rotating bending fatigue properties was test with QT, QT nitiding 8 h, QT nitriding 48 h specimens. Fish-eye type crack formation occurred and the two crack initiation modes, fish-eye crack initiation and surface crack initiation, were observed by the scanning electron microscope and discussed. The result showed that the fatigue strength of QT specimens were improved by 54% at least compared with the untreated specimens. But the QT and un-QT have the mainly same fatigue strength in the same plasma nitriding condition, especially no-improvement with the 48 h plasma nitriding specimens.
LOW CYCLE FATIGUE BEHAVIOR AND LIFE PREDICTION OF A CAST COBALT-BASED SUPERALLOY
Authors: YANG HO-YOUNG , KIM JAE-HOON , YOO KEUN-BONG
Published: March 2012

Co -base superalloys have been applied in the stationary components of gas turbine owing to their excellent high temperature properties. Low cycle fatigue data on ECY-768 reported in a companion paper were used to evaluate fatigue life prediction models. In this study, low cycle fatigue tests are performed as the variables of total strain range and temperatures. The relations between plastic and total strain energy densities and number of cycles to failure are examined in order to predict the low cycle fatigue life of Cobalt-based super alloy at different temperatures. The fatigue lives is evaluated using predicted by Coffin-Manson method and strain energy methods is compared with the measured fatigue lives at different temperatures. The microstructure observing was performed for how affect able to low-cycle fatigue life by increasing the temperature.
A STUDY ON EXPERIMENTS AND SIMULATIONS FOR DUCTILE FRACTURE OF ISOTROPIC MATERIAL USING ROUSSELIER'S DAMAGE MODEL
Authors: Guo Junhang , Murakami Ri-ichi , Zhao Shengdun
Published: March 2012

Ductile fracture has been a hot topic for a long time for its importance to mechanical design in evaluating the risk of failure. In this paper, the A5052BD-H14's ductile fracture is studied using a new constitutive equation based on the continuum damage mechanics. A novel full-implicit stress integration algorithm is developed based on Rousselier's damage model and implemented into finite element analysis (FEA) models by the ABAQUS/Explicit using the user material subroutine. The tensile tests of A5052BD-H14 with notch were taken and the load-displacement curves were recorded. By simulations, the evolutions of the void volume fraction are obtained and can be used as calibration for the critical void volume fraction. The validity of the damage model and the proposed stress integration algorithm are verified by comparing the experimental results and the simulation results. Further, by using the critical void volume fraction and element deletion, the simulation results show that this method is reliable, and can be used to predict the fracture of metals.
EFFECT OF LOAD RANGE ON PROBABILISTIC FATIGUE CRACK GROWTH RESISTANCE IN FLUX CORED ARC WELDED API 2W GR. 50 STEEL
Authors: KIM SEON-JIN , SOHN SANG-HOON , SOHN HYE-JEONG
Published: March 2012

The aim of this paper is to investigate the effects of the load range on the spatial variation of fatigue crack growth resistance in three different zones, WM, HAZ and BM for flux cored arc welded API 2W Gr. 50 steel using the stochastic model based on reliability theory. Experimental fatigue crack growth tests were performed on ASTM standard CT specimens. The results indicates that the load range has strong dependency on probabilistic fatigue crack growth for the three different zones WM, HAZ and BM, and also the spatial variation of fatigue crack growth resistance.
PREDICTION FOR FATIGUE CRACK GROWTH IN NOTCHED PLATES
Authors: SHOJIMA K. , YANASE K. , ENDO M.
Published: March 2012

The notch is usually unavoidable in designing various mechanical components. As well known, those notches significantly influence the fatigue life and fatigue strength of materials. In addition, most fatigue cracks spend the vast majority of their lives as short cracks, and the behavior of such flaw is of significant importance in determining the fatigue lifetime of notched components. Correspondingly, in this research, we investigate the fatigue crack growth behavior and fatigue strength of notched plates. For the proposed method, the elastic-plastic behavior, the Kitagawa effect and the crack closure are taken into account as the major factors responsible for the peculiar behavior of small fatigue cracks emanating from notches. Regarding the experiment, the fatigue tests were conducted using the plates with a circular notch under uniaxial loading condition. The proposed approach is validated by comparing the predicted results to the experimental data.
FATIGUE CRACK GROWTH OF AGE-HARDENED Al ALLOY UNDER ULTRASONIC LOADING
Authors: CHEN Q. , KAWAGOISHI N. , KARIYA K. , NU Y. , GOTO M.
Published: March 2012

An age-hardened and extruded Al alloy 7075-T6 was fatigued under both ultrasonic loading (20kHz) and rotating bending (50Hz) in the environments of controlled humidity, distilled water and oxygen gas respectively, to investigate the availability of ultrasonic fatigue test as a time-saving tool for the reliability evaluation of materials subjected to conventional frequency loading. Although fatigue strength decreased slightly at relative humidity below 60-70%, it degraded significantly when the humidity was increased beyond that level, irrespective of the loading frequency. However, the mechanisms of strength degradation involved in high humidity are quite different. Under rotating bending, fatigue strength decreased because crack growth was accelerated due to brittle fracture, whileas the decrease in fatigue strength under ultrasonic loading was caused by crack propagation transition from tensile mode to shear mode cracking.
FATIGUE CRACK GROWTH BEHAVIOR OF STAINLESS STEEL COATED WITH TiN FILM
Authors: FUKUI SATOSHI , YONEKURA DAISUKE , MURAKAMI RI-ICHI
Published: March 2012

In our previous study, we examined the influence of the fatigue properties of the stainless steel coated with TiN film and clarified the influence of TiN coating and the surface roughness on the fatigue property. In this study, the four point bending fatigue crack growth tests were carried out for martensitic stainless steel coated with TiN film deposited by arc ion plating method in order to investigate the effect of surface finishing on the fatigue crack behavior for film coated material. The fatigue crack growth behavior was evaluated using the replica method. As a result, the crack propagation rate of mirror polished specimens were lower than that of rough surface specimens. The crack propagation rate was especially decreased for TiN coatings deposited on the mirror polished substrate. The surface roughness near the crack initiation site increased after fatigue test. It concludes that the surface roughness of substrate influences crack propagation rate and the deposition of TiN film affected influenced crack propagation rate and fatigue strength when the surface roughness of substrate is small enough.
EFFECTS OF AGING STRUCTURES AND HUMIDITY ON FATIGUE PROPERTIES OF MARAGING STEEL
Authors: HAYASHI KOUSUKE , NAGANO TAKANORI , MORIYAMA MICHIHIKO , WANG XISHU , KAWAGOISHI NORIO
Published: March 2012

Effects of aging structures and humidity on fatigue properties of 350 grade 18% Ni maraging steel were investigated under rotating bending in relative humidity of 25% and 85%. Aging conditions tested were a conventional single aging and a double one which was aged at low temperature after the conventional aging. In each aging, under and peak aged steels were prepared. Tensile strength was increased by the double aging without reduction of the ductility. Proportional relation between fatigue limit and Vickers hardness held until 750HV in low humidity. However fatigue strength was largely decreased by high humidity, especially in the peak aged steel at the single aging. The decrease in fatigue strength by high humidity was mainly caused by the acceleration of a crack initiation due to the anodic dissolution. The acceleration of a crack initiation was larger in the steel peak aged at the single aging with larger precipitated particles.
INFLUENCE OF CARBON CONTENT ON FATIGUE STRENGTH OF DRAWN STEEL TUBES FOR SMALL ONCE-THROUGH BOILER
Authors: YONEKURA DAISUKE , FUJIE YUTA , MURAKAMI RI-ICHI , TOKUNAGA YUKIHIRO
Published: March 2012

Tension-tension fatigue tests were performed to examine the influence of carbon content on the fatigue properties of drawn specific steel tube (STB340) with/without post heat treatment for small once-through boiler. Two different carbon content steel tubes, C =0.06 and 0.12% were prepared. The as-received, as-drawn and post drawing heat treated series for each carbon content tube were prepared for fatigue test. The hardness, grain size and residual stress were measured for each series. As a result, the fatigue strength of as-received and as-drawn series showed a small difference between C =0.06 and 0.12% specimens. However, the post drawing heat treatment series showed obvious difference in the fatigue strength. The fatigue strength of higher carbon content tubes significantly decreased by the post drawing heat treatment, whereas the decrease of fatigue strength was little for lower carbon content heat treated tubes. The difference of fatigue strength was mainly caused by the degree of relaxation of work hardening by post heat treatment.