bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Interactions Between the Vadose and Phreatic Zones During Breaking Solitary Wave Runup and Drawdown Over a Fine Sand Beach
Authors: Xiao Heng , Young Yin L. , Pre´vost Jean H.
Published: February 2010

The objective of this work is to investigate the dynamic interactions between the vadose and the phreatic zones during breaking solitary wave runup and drawdown over a fine sand beach. Extreme wave runup and drawdown in the nearshore region can lead to soil failure in the form of severe erosion, liquefaction, or slope instability. However, the physics of the nearshore region is difficult to simulate numerically due to the greatly varying time scales between the four governing processes: loading and unloading caused by wave runup and drawdown, propagation of the saturation front, pore pressure diffusion, and soil consolidation. Such processes are also difficult to simulate experimentally via model-scale wave tank studies due to the inability to satisfy all the similarity requirements for both the wave and the porous media in a 1g environment. Hence, the goal of this work is to perform a 1D study using a multiphase model to describe the transient responses of the species saturation, pore fluid pressure, effective stresses, and skeleton deformation. Results are shown for three simulations: (1) full-scale simulation, (2) 1:20 laboratory-scale simulation without scaling of the porous media, and (3) 1:20 laboratory-scale with consistent scaling of the soil permeability. The results suggest that the scaling of porous media between the pore fluids and soil skeleton has a significant influence on the transient response of both the vadose and the phreatic zones.
Motion Prediction of the Ship With Sloshing Tanks
Authors: Zou Kang , Miao Quan-ming , Zhu Ren-qing
Published: February 2010

Sloshing flow in ship tanks is excited by ship motions, but it affects the ship motions in reverse. This paper focuses on the motion responses of the ship in waves with consideration of coupled effects with sloshing in tanks. A three-dimensional panel method in time-domain is applied to solve the ship motion problem, and the sloshing tanks are solved by commercial CFD software simultaneously. Experiments were carried out on a SL175 ship and good agreement is obtained.
Unsteady Potential Flow Theory and Numerical Analysis of Forces on Cylinders Induced by Nearby Oscillating Disturbances
Authors: Valentine Daniel T. , Madhi Farshad
Published: February 2010

The complete solution of several two-dimensional potential flow problems are reported that deal with the unsteady flow around circular cylinders. Three of the flows considered are induced by an oscillating disturbance near the cylinder. The three elemental disturbances examined are (1) a pulsating source, (2) a pulsating doublet and (3) a pulsating vortex. The formulas for the force acting on the cylinder due to each of the elemental disturbances were derived by applying the method of images and checked by deriving the equivalent surface distribution of sources to model the cylinder starting with Green’s second identity. The theory helped direct the development of a boundary-integral numerical model described and applied in this paper to solve the unsteady flow around a circular cylinder due to an arbitrarily specified oscillatory disturbance near the cylinder. The numerical method is validated by comparing predictions of the force with the exact solutions.
Linear Stability Approach to Explain Lock-In Transition and Time Sharing in Vortex-Induced Vibrations of Slender Structures
Authors: Violette Re´mi , Szydlowski Julien , de Langre Emmanuel
Published: February 2010

In this paper, we use a linearized version of a wake oscillator model in order to understand VIV of flexible structures. By a simple analytical development on the stability of an infinite cable/wake system, we demonstrate the existence a temporal instability. The theoretical study is pushed further to finite structure, a tensioned cable, for which modes frequency, amplitude growth rate in time and velocity range of instability are easily derived. The developed concepts are used to explain experimentally observed behaviours of a low flexural rigidity tensioned beam undergoing VIV.
Influence of a Roller Clump on the Seabed
Authors: Ivanovic´ Ana , Neilson Richard , Chima-Okereke Chibisi , Zhu Jianfeng
Published: February 2010

The effect of the impact of trawl gears on benthic communities has been of concern during the last couple of decades. Knowledge of the response of benthic habitats to impacts from fishing gear is of great importance to the ecosystem and the management of sustainable fisheries. A European project, DEGREE (DEvelopment of Fishing Gears with Reduced Effects on the Environment), addresses this concern by focusing on quantifying the environmental and ecological impacts of fishing, developing fishing gears with reduced environmental impact, and assessing the socio-economic consequences of these changes. This paper is a preliminary study focusing primarily on the comparison between laboratory and finite element (FE) modelling of the interaction between a gear component, the roller clump of a twin trawl, and the seabed in terms of penetration and disturbance of the sediment. The FE model and experimental rig are described. Initial outputs of penetration depth from the FE calculations show that the model is highly sensitive to the yield stress and that further investigation is required to achieve full parity with laboratory observations on dry sand.
Large Scale Tests of Strain Capacity of Pipe Sections With Circumferential Defects Subjected to Installation-Induced Plastic Strain History
Authors: Nyhus Ba˚rd , O̸stby Erling , Zhang Zhiliang , Olso̸ Erlend , Ro̸stadsand Per Arne , Eikrem Pa˚l Are
Published: February 2010

Installation of offshore pipelines by reeling introduces plastic pre-straining. The pre-strain history is not homogenous and it will vary around the circumference of the pipe. The pre-strain history will modify the yield and flow properties. Also, the fracture toughness may be influenced by the pre-straining. The result is that the bending strain capacity of pipelines during operation will differ depending on how the bending moment coincides with pipe orientation during installation. Three full scale tests of 12″ x-60 pipes with wall thickness 19.3mm and a 3×100 mm outer surface defect were performed to investigate the effect of pre-strain history. Two pipes were pre-strained in bending to 2% strain in the outer fibre and then straightened to simulate the reeling. The final tests to establish the strain capacity during operation as a function of strain history were performed in four point bending with an internal pressure of 325 bar. The strain capacity for the side of the pipe that ends in tension and the side that ends in compression from pre-straining was 1.7% and 2.6% respectively. The strain capacity of the third test without pre-straining was 5.7%. The results show that pre-straining will modify the strain capacity and the effect must be taken into account in engineering critical assessment of pipes during operation. The effect of prestraining should be evaluated for all installation methods that involve plastic deformation during installation, and not only reeling. It is important to note that the notch size in the full scale tests was larger than what would normally be accepted for reeling. In addition the notch was positioned in base material and not in weld metal, which is a more realistic position for a notch. The welds are normally overmatched and this might reduce the effect of prestraining.
A Coupled Finite Element-Element Free Galerkin Method for Liquefiable Soil-Structure Interaction Analysis Under Earthquake Loading
Authors: Tang Xiaowei , Jie Ying , Luan Maotian
Published: February 2010

This study presents a numerical method for the seismic behavior assessment of liquefiable soil-structure interaction. In the method, the element-free Galerkin method (EFGM) is applied to simulate the behavior of the liquefiable sandy soil which will take place large permanent deformation under earthquake loading. The finite element method (FEM) is used to describe the behavior of the structure. Then, the EFGM and FEM are related by contact elements. The cyclic elasto-plastic constitutive model and updated Lagrangian large-deformation formulation are jointly adopted to establish the governing equations in order to take account for both physical and geometrical nonlinearities. The shape function is established by moving least squares method while hexahedral background cells are used. The essential boundary conditions are treated with the help of the penalty method. The coupled method can avoid the volumetric locking in the numerical computations using finite element method when non-uniform deformations happen. In order to assess the effectiveness and accuracy of the current procedure, numerical simulation of caisson-type quay wall subjected to earthquake motion is conducted.
Calibration of Flaw Extension Model Under Ratcheting Fatigue
Authors: Gioielli Paulo , Buitrago Jaime , Kan Wan , Weir Michael , Chell Graham , Hudak Stephen J.
Published: February 2010

Ratcheting fatigue loading arises from the superposition of elastic cyclic loads and monotonically increasing mean strains well into the plastic domain, resulting in simultaneous tearing and fatigue of initial welding flaws. The ratcheting loads may be due to thermal gradients set by startups and shutdowns or by soil uplifts and settlements. Under these conditions, fatigue and fracture phenomena could interact, accelerating the extension of initial fabrication flaws above that predicted to occur by either mechanism acting alone. Evaluation of ratcheting fatigue behavior will impact the weld inspection criteria that ensure pipeline integrity. A previous paper [Gioielli, et al ’08] described a model that evaluates 1) tearing based on applied elastic-plastic driving force (J) versus tearing resistance obtained from standard J-R curve tests and 2) tearing-fatigue based on an extension of Paris law re-expressed in terms of an effective ΔJ instead of ΔK enabling it to be extrapolated to the very high growth rates encountered in the elasto-plastic regime. The model was successfully calibrated to small-scale tests. This paper extends the model calibration to large-scale welded pipe tests subjected to cyclic tensile loads while internally pressurized. To that end, 1) new J solutions were developed for pressurized pipes under load-controlled conditions, and 2) comparisons were made of predicted flaw extensions to those obtained experimentally from full-scale tests. The model predictions using average tensile properties and SENT-based tearing resistance of flaw extensions compared favorably to those measured in the large-scale tests, but additional tests are needed before the model can be used in design.
State of the Art of Experimental Studies and Predictive Methods for Slug Liquid Holdup
Authors: Pereyra E. , Arismendi R. , Gomez L. , Mohan R. , Shoham O. , Kouba G.
Published: February 2010

Determination of gas entrainment in slug flow is crucial for the prediction of slug flow characteristics and separator performance. A summary of all available correlations and mechanistic models for the prediction of slug liquid holdup is presented. Additionally, an experimental data base for slug liquid holdup has been collected from available literature. The data base shows a gap for large diameter pipes, high pressure systems and high viscosity liquids. A comparison between the predictions of available models and correlations against the data base is presented, identifying the range of applicability of the different methods. The correlations have been tuned with the new data showing an improved performance. Also, the uncertainties of the correlations parameters are evaluated and presented. Based on this study, a recommendation for the best method for predicting the slug liquid holdup is provided.
Utilization of Gas-Liquid Cylindrical Cyclone (GLCC©) Compact Separator for Solids Removal—Part II: Operational Envelope for Carry-Over
Authors: Omarov S. , Gomez L. , Wang S. , Mohan R. , Shoham O. , Oglesby K.
Published: February 2010

The operational envelope for particle (solid and liquid) carry-over (OPEN-CO) in the GLCC© has been studied experimentally and theoretically. The experimental data were acquired for a wide range of flow conditions, including: inlet superficial gas and liquid velocities between 15–35 ft/s and 0.1–1.2 ft/s, respectively, solid particle sizes of 5, 25 and 50 microns, and solid mass flow rates between 6.61lbm/min and 15.43 lbm/min. An uncertainty analysis of the experimental data revealed uncertainties less than 1% and less that 8.5% for the superficial liquid velocity and the superficial gas velocity measurements, respectively. Results from the experimental data show that as the density of the slurry increases (higher solid mass flow rates), the OPEN-CO shifts up. A mechanistic model was developed for the prediction of OPEN-CO, based on particle trajectory. The model assumes that the particle (liquid and solid) density is the same as the slurry density. Model predictions agree well with the experimental data. The developed model can be used for design and efficient operation of the GLCC© for gas-liquid-solid flow (gas slurry separation).
Full-Scale Validation of a Flaw Assessment Methodology for Welded and Reeled Pipes
Authors: Chell Graham , Hudak Stephen J. , Lee Yi-Der
Published: February 2010

Pre-existing weld flaws in pipes subjected to high strains resulting from reeling installation may extend by combined ductile tearing and low-cycle fatigue (LCF). The increase in flaw sizes from this process will reduce the flaw tolerances of reeled pipes subjected to subsequent service high-cycle fatigue (HCF) exposure compared to the tolerances determined ignoring the reeling process. This paper describes a flaw assessment methodology that includes the synergy between ductile tearing and LCF flaw growth due to reeling. The methodology utilizes the Level 3C (J-based) failure assessment diagram (FAD) approach of BS 7910 to explicitly account for the effects of flaw and pipe geometries, as well as material stress-strain behavior, on the crack tip driving force, J. The Level 3C FADs used herein are derived from and validated against the results of a matrix of J-based finite element analyses (FEA) of pipes. They have been incorporated into the computer program FlawPRO™ developed for the offshore industry that enables a comprehensive engineering critical assessment (ECA) for flawed reeled pipes to be performed. The methodology incorporated into FlawPRO is validated against the results of full-scale tests on reeled pipes containing weld flaws subjected to a variety of reeling scenarios. The validation includes investigations into the effects on predicted flaw growth of using J-resistance curves measured on SENB and SENT specimens and of assuming strain versus load controlled reeling. The best agreement with the flaw extensions measured in the full-scale tests is obtained when an SENT J-R curve is used together with assuming reeling occurs under strain controlled conditions. It is concluded that the reeling methodology in FlawPRO is successfully validated by the full-scale test results.
Conceptual Studies of a Flexible Fiber Composite Manufacturing Cell for Maritime Engineering
Authors: McCormick Darryn , Kahlen Franz-Josef
Published: February 2010

Fiber reinforced polymer composites offer a range of advantages as a material for manufacturing in the maritime industry, ranging from weight savings to accurate design due to the anisotropic nature of the material. These advantages are outweight in practical terms by significant waste of the raw materials and their labor-intensive work and handling. This report presents the development of a flexible manufacturing system which is designed to the level of a flexible manufacturing cell. The purpose of this report is the design of an implement-able flexible fiber composite manufacturing system, considering the dynamics and limiters to flexibility. This system is to minimize production time and costs of composite parts while considering start-up costs, running costs and part production time. Goal posts were defined for competitiveness of the system with conventional metal systems and a reduction of labor requirements and waste material. The designed system is reported on and results are presented.
Drift Forces on a Floating Body of Simple Geometry Due to Second Order Interactions Between Pairs of Harmonics With Different Frequencies
Authors: Pessoa Joa˜o , Fonseca Nuno , Guedes Soares C.
Published: February 2010

The paper presents an investigation of the slowly varying second order drift forces on a floating body of simple geometry. The body is axis-symmetric about the vertical axis, like a vertical cylinder with a rounded bottom and a ratio of diameter to draft of 3.25. The hydrodynamic problem is solved with a second order boundary element method. The second order problem is due to interactions between pairs of incident harmonic waves with different frequencies, therefore the calculations are carried out for several difference frequencies with the mean frequency covering the whole frequency range of interest. Results include the surge drift force and pitch drift moment. The results are presented in several stages in order to assess the influence of different phenomena contributing to the global second order responses. Firstly the body is restrained and secondly it is free to move at the wave frequency. The second order results include the contribution associated with quadratic products of first order quantities, the total second order force, and the contribution associated to the free surface forcing.
A Study on the Retention of Port Distribution Functions at the Time of Earthquake: Business Continuity Management
Authors: Miyamoto Takujiro , Masuda Koichi , Kondo Takeo , Arai Yoichi
Published: February 2010

This is a study on how to retain distribution functions at the port in the large-scale industrial disaster prevention scheme at the time of great earthquakes. Urgent need for such efforts has been mounting in recent years. Industrial disaster prevention scheme is, in other words, Business Continuity Management (BCM), which enables continuity of important businesses while trying to make an early recovery of overall business activities at the time of great earthquakes. When an earthquake occurs, it is important to quickly resume businesses after an initial period of confusion. For this purpose, it is necessary to make a large-scale restoration plan, including the restoration of social infrastructure. In the Chubu Metropolitan Area in Japan where the city of Nagoya is the center, the global division of labor has been rapidly in progress. The businesses are developing more and more within the framework of closely and finely-knit global supply-chains between domestic and overseas enterprises. It is one of the areas where Business Continuity Management is in urgent need. The subject of the case study in this paper is all international distribution activities at the Port of Nagoya in the Chubu Metropolitan area where Tokai, Tou-Nankai or Nankai Earthquakes is anticipated in the near future. The concept of the Business Continuity Management shall be developed through research on the current measures taken by the enterprises and organizations who are the port-users. Then the goals and problems regarding the recovery of port functions will be identified. Furthermore, we will attempt to propose technological means to solve the problems and achieve the goals. This paper starts with the analysis of the questionnaires to about 30 member companies and organizations of Industry Disaster Management Panel. The next section consists of two parts; the first half is devoted to the function recovery planning on the shore, and the second half discusses the function restoration of the section on the sea within the port. We believe this study will provide valuable guidelines for the port function recovery in the Chubu area at the time of earthquakes. It will also serve as effective guiding philosophy for many ports in Japan and around the world which face similar problems.
Application of a Series of Submerged Breakwaters to Coastal Protection
Authors: Hsu Tai-Wen , Chang Jen-Yi
Published: February 2010

The feasibility of a plenary of breakwater is explored through a combined program of a prototype field test. The breakwater consists of a series of low height, shore-parallel bars which are placed just outside the surf-zone. The incident wave field is strongly reflected when the incident wave length is equal to twice the distance between adjacent bars. The breakwater acts to shelter the beach against storm wave attack and to build a tombolo sand deposit behind the breakwater. Numerical results indicated that the Bragg reflection breakwater concept may have considerable merit, however, many paper tests served to demonstrate the many practical difficulties in implementing the concept.
A Cohesive Element Framework for Dynamic Ice-Structure Interaction Problems—Part II: Implementation
Authors: Konuk Ibrahim , Gu¨rtner Arne , Yu Shenkai
Published: February 2010

A framework incorporating dynamic crack propagation and continuum mechanics for modeling ice-structure interaction processes is developed. The framework is build upon a comprehensive review of recent developments in the analysis of dynamic fragmentation problems for materials such as ceramics, concrete, and metals. A review of alternative crack propagation modeling methods is also included in order to illustrate how the developed framework may overcome the shortcomings of existing techniques. This is the second paper (Part II) in a series of three papers. In the first paper (Part I), formulation of the framework is presented. Issues related to the implementation of the developed framework are discussed in this paper. The application of the framework to various ice-structure interaction problems will be presented in Part III along with the demonstration and investigation of important aspects of these problems.
Histones and Alternative Splicing
Authors: Riddihough Guy
Published: February 2010

Histone modifications regulate alternative splicing through physical crosstalk with the splicing machinery.
Comparative Activities of TR-700 (Torezolid) against Staphylococcal Blood Isolates Collected in Spain
Authors: Betriu Carmen , Morales Gracia , Rodríguez-Avial Icíar , Culebras Esther , Gómez María , López-Fabal Fátima , Picazo Juan J.
Published: February 2010

The
in vitro
activity of TR-700 (torezolid) was evaluated against a collection of 660 staphylococcal blood isolates. TR-700 showed excellent activity against all the staphylococci tested. The MIC
50
and MIC
90
values of TR-700, linezolid, daptomycin, and vancomycin against methicillin-resistant
Staphylococcus aureus
(MRSA) isolates were 0.25 and 0.5, 2 and 4, 0.5 and 0.5, and 1 and 2 μg/ml, respectively. TR-700 demonstrated greater
in vitro
potency than linezolid against staphylococci, including linezolid-resistant and vancomycin-nonsusceptible strains, and was 32-fold more active than linezolid against the seven
cfr
-positive MRSA strains tested.
Concomitant EnterotoxigenicEscherichia coliInfection Induces Increased Immune Responses toVibrio choleraeO1 Antigens in Patients with Cholera in Bangladesh
Authors: Chowdhury Fahima , Begum Yasmin A. , Alam Mohammad Murshid , Khan Ashraful I. , Ahmed Tanvir , Bhuiyan M. Saruar , Harris Jason B. , LaRocque Regina C. , Faruque Abu S. G. , Endtz Hubert , Ryan Edward T. , Cravioto Alejandro , Svennerholm Ann-Mari , Calderwood Stephen B. , Qadri Firdausi
Published: February 2010

Vibrio choleraeO1 and enterotoxigenicEscherichia coli(ETEC) are major bacterial pathogens that cause dehydrating disease requiring hospitalization of children and adults. The cholera toxin (CT) produced byV. choleraeO1 and the heat-labile toxin (LT) and/or heat-stable toxin (ST) of ETEC are responsible for secretory diarrhea. We have observed that about 13% of hospitalized diarrheal patients are concomitantly infected withV. choleraeO1 and ETEC. In order to understand the outcome of such dual infections on the clinical and immunological responses in cholera patients, we studied patients infected withV. choleraeO1 (group VC;n= 25), those infected with bothV. choleraeO1 and ETEC (group VCET;n= 25), and those infected with ETEC only (group ET;n= 25). The VCET group showed more severe dehydration and had a higher intake of intravenous fluid and more vomiting than the ETEC group (P= 0.01 to 0.003). The VCET patients showed higher vibriocidal responses and increased antibody titers to cholera toxin and lipopolysaccharide (LPS) in plasma than did theV. choleraeO1 patients (P= 0.02 to <0.001). All responses in theV. choleraeO1 and in the VCET groups were more robust than those seen in the group infected with ETEC only (P= 0.01 to <0.001). We thus show that concomitant colonization with ETEC induces immune responses toV. choleraeantigens that are more robust than those seen withV. choleraeO1 infection alone. It is possible that LT or other factors expressed by ETEC may play a role as a mucosal adjuvant in enhancing the immune responses toV. choleraeO1.
Indeterminate shoot extension and heterophylly in Acersaccharum
Authors: Powell G. R. , Tosh Kathleen J. , MacDonald Joanne E.
Published: February 2010

Shoots of Acersaccharum Marsh., with at least three long internodes were of two types: long determinate shoots (LDS) usually quickly expanding three or four pairs of preformed leaves and then developing terminal buds; and indeterminate shoots (IS) similarly expanding usually four pairs of preformed leaves and then several pairs of neoformed leaves before developing their terminal buds. The neoformed leaves were smaller, of different shape, and took longer to complete expansion than the preformed leaves. The mature form of the preformed leaves was related to the degree of development of the leaves in the overwintering buds. The last pair of preformed leaves was sometimes intermediate in morphology between earlier preformed and neoformed leaves. The last two pairs of lateral buds on IS were generally formed close together below the terminal bud because internode extension between the last two pairs of neoformed leaves was minimal. On LDS, there was a long internode between the last two pairs of preformed leaves, thus, only one pair of lateral buds was situated close to the terminal bud.
Plot size and number of plots needed to assess spruce budworm impact
Authors: Karpinski Jr. Chester , Witter J. A.
Published: February 2010

This study investigated size and number of plots needed to precisely estimate tree mortality, mean dead basal area, mean dead volume, mean live basal area, and mean live volume in stands infested with the spruce budworm, Choristoneurafumiferana (Clemens).Depending on the parameter, precision of four different plot sizes (0.02, 0.04, 0.08, 0.40 ha) was examined. For most parameters the 0.04-ha plot appears to be approximately as precise as the larger plot sizes. Variables which affect the precision of the plot sizes are percent mortality, patchy distribution of the character of interest, and the variability associated with the population of interest. The precision of two, three, four, and five plots per stand was investigated. The coefficient of variation of the mean is reduced the greatest between two and three plots; subsequent reductions beyond three plots are not great. The number of plots needed based on sampling theory varied according to the parameter and the variability associated with the parameter. It was determined that the time involved in evaluating three 0.04-ha plots was approximately the same as needed to evaluate two 0.08-ha plots.
Further observations on the pollination mechanism and seed production of Douglas-fir
Authors: Owens John N. , Simpson Sheila J.
Published: February 2010

The pollination mechanism of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) was studied. Pollen stained five different colors and applied to the same conelets at five different times showed that the pollen applied on the 1st and 3rd days after conelets became receptive was taken into the micropyle in significantly greater quantities than pollen applied at later dates. A second supplemental pollination did not increase the seed efficiency for individual cones. Seeds produced when an average of less than 1.2 pollen grains were taken into the micropyle had essentially the same germination percentage and proportion of abnormal germinants as seeds resulting when an average of 3.4 or more pollen grains were taken into the micropyle.
An evaluation of electrical resistance as a measure of vigor in eastern white pine
Authors: Kostka Stanley J. , Sherald James L.
Published: February 2010

Differences in tree vigor were observed in a planting of eastern white pine, Pinusstrobus L. Trees were visually classified into four vigor classes. Electrical resistance (ER) readings of the cambial zone and growth measurements of needles, internodes, and annual rings were compared for each class. Mean ER readings were related inversely to vigor; however, only mean readings for class 1, most vigorous, and class IV, least vigorous, trees were significantly different on four reading dates. Mean growth measurements of needles, internodes, and annual rings were significantly different for all four vigor classes.
AN EXTENSION OF THE CLASSICAL GAUSS SERIES-PRODUCT IDENTITY BY BOSON–FERMIONIC REALIZATION OF THE AFFINE ALGEBRA $\widehat{\mathfrak{gl}}_n$
Authors: ŠIKIĆ TOMISLAV
Published: February 2010

The main results of this paper are two infinite families of series-product identities which are based on a classical Gauss identity and two different interpretations of characters of fundamental modules for the affine Kac–Moody Lie algebra [Formula: see text], one of them stemming from a boson–fermionic realization of the affine Lie algebra [Formula: see text].
Carbon Containing Titanium Coating for Ti6Al4V Implants
Authors: Ruiz de Gopegui Unai , Bayón Raquel , Zubizarreta Cristina , Sáenz de Viteri Virginia , Fernández Xana
Published: February 2010

Ti6Al4V alloy is commonly material employed in orthopaedic implants, especially in knee joint applications due to its good corrosion resistance in biological media. But mechanical loads, wear and corrosion effects present in this type of systems, can affect drastically the system properties provoking the prosthesis failure and the need of component replacement. One alternative for improving the corrosion and fretting resistance of these biomaterials is the application of protective and biocompatible diamond like coatings (DLC). In this work, a type of metallic Ti-DLC coating deposited by physical vapour deposition (PVD) cathodic arc method on Ti6Al4V substrate is proposed. Different deposition process parameters were analyzed in order to determine the mechanic-chemical properties of the coated substrates. Corrosion, tribocorrosion and fretting properties of these films are analyzed and compared with the substrate ones in simulated biological fluids.
Chemical Vapor Deposition Synthesis of Carbon Nanotubes Using Iron Catalysts
Authors: Abdel-Fattah Tarek M. , Williams Phillip , Wincheski Russell , Shams Qamar
Published: February 2010

Single-walled carbon nanotubes (SWNTs) were synthesized via a novel chemical vapor deposition (CVD) technique incorporating iron catalysts. Stable aqueous solutions of the nanotubes using the anionic surfactant sodium dodecylbenzene sulfonate were also obtained, and the properties of as-produced SWNTs were documented through atomic force microscopy and Raman spectroscopy and compared with purified HiPCO SWNTs as a reference.
Surface Electrochemical Treatment of Carbon Materials for Supercapacitors
Authors: Uvarov Nikolai F. , Mateyshina Yulia G. , Ulihin Artem S. , Yusin Stepan I. , Varentsova Valentina I. , Varentsov Valery K.
Published: February 2010

Carbon fiber materials (CFM) were electrochemically treated in cathodic, anodic or combined regimes. The influence of the treatment on morphology and chemical composition of CFM was investigated. It was shown that the electrochemical treatment does not substantially influence on the electrical capacitance of CFM. Nevertheless, it facilitates the process of electrosorption of MnO(OH)2 colloidal particles onto CFM surfaces. CFM samples modified by MnO(OH)2 have a specific capacitance of 70-80 F/g.
Growth and Field Emission Characteristics of Pillar-Like Carbon Nanotubes Using Co-Ti/Al Co-Deposited Multilayer Catalyst at Low Temperature
Authors: Chang Chia-Tsung , Lee Chein-Ying , Lin Kao-Chao , Lai Rui-Ling , Tsai Wan-Lin , Chien Yun-Shan , Juan Chuan-Ping , Lee I-Che , Yang Po-Yu , Wei Inn-Zang , Cheng Huang-Chung
Published: February 2010

In this essay, the pillar-like CNT field emission arrays synthesis with co-deposited catalysts at low temperature (550°) was proposed. Pillar-like CNT has been successfully synthesized by thermal CVD system. The current density of this proposed pillar like CNTs was as high as 1272 μA/cm2 at 6 V/μm and the turn-on field was 3.6 V/μm. Additionally, the reliability was more stable as lower than 7% degradation of initial current density.
Optical-Gating and Carrier Modulation Effects in Single-Walled Carbon Nanotube: Oxide Interfaces for Opto-Electronic Device Applications
Authors: Kouklin Nikolai , Omari Mones
Published: February 2010

In this study the effects of photo-electric modulation of free carrier density in heterogeneous ZnO- single-walled carbon nanotubes random networks engineered by solution processing technique have been investigated. The current-voltage characteristics obtained on the SWNTs -ZnO devices were non-rectifying and Ohmic-like in the dark and when exposed to optical radiation. The UV photoresponse was measured comparatively on the SWNT and SWNT-ZnO assemblies. While the conductivity of SWNTs thin films was observed to increase by ~ 7 % under UV illumination, similarly tested SWNT-ZnO samples consistently exhibited a decrease in conductivity upon exposure to UV radiation yielding a net negative change of ~10% associated with the formation of ZnO-SWNT interface. The effect of strong optical gating is explained within the model of interface-mediated charging/discharging effects. The study creates a possibility of engineering reduced-cost and multi-range nanotube light sensors based on extrinsic carrier modulation via external gating at the interface.
The Regularities of Electrolytic Dissociation of Mesaconic and Itaconic Acids
Authors: Kvaratskhelia Elene , Kvaratskhelia Ramaz
Published: February 2010

With the aid of the suggested by authors original method the dissociation parameters for the dilute (0.0001-0.1M) solutions of mesaconic and itaconic acids were determined. Together with the equations for the accurate calculation of these parameters the simple empirical equations for the fast approximate calculation of the latters are also suggested.
Effect of Pre-Cleaning on Texturization of c-Si Wafers in a KOH/IPA Mixture
Authors: Chen Gim , Kashkoush Ismail
Published: February 2010

Experiments were performed to investigate the effect of pre-cleaning on surface texturization of mono-crystalline silicon in an KOH/IPA solution. Without appropriate pre-cleaning, surface contamination can cause the formation of pyramids with smaller sizes than those at the non-contaminated areas, leading to inhomogeneous texture features and reflectance non-uniformity on the wafer surface. Depending on the supplier, the surface quality and contamination level of wafers may vary and the pre-cleaning condition may need to be tailored to achieve consistent and desired texturization results.
Numerical Analysis of Oxygen and Carbon Transport in a Unidirectional Solidification Furnace
Authors: Gao B. , Kakimoto Koichi , Nakano S.
Published: February 2010

A global simulation of coupled oxygen and carbon transport in a unidirectional solidification furnace was carried out for accurate prediction of distributions of carbon and oxygen impurities in multicrystalline silicon material for solar cells. Both the gas flow and silicon melt flow were coupled each other. Five chemical reactions were taken into account during the transportation of the impurities.
Synthesis and Characterization of Nanoporous TiO2 Films on Silicon Substrates for Solar Cells Applications
Authors: Manea Elena C. , Obreja Cosmin , Popescu Alina , Purica Munizer , Schiopu Veronica , Staicu Liliana , Comanescu Florin , Parvulescu Catalin
Published: February 2010

Nanoporous titanium oxide layers were prepared by anodization of titanium thin films deposited on silicon substrate by sputtering, using a mixture of ammonium fluoride and ethylene - glycol as electrolyte. The dependence of pore morphology and pore formation rate on process parameters was evaluated. The influence of anodization conditions (e.g. electrolyte composition, current density, pH, time and temperature) on the structure and morphology of the oxide layer and the changes induced by the heat treatment, were also investigated by SEM, FTIR, Raman spectroscopy and X - ray diffraction.
Solution-Based n-Type Doping in Metal Oxides for Next-Generation Solar Cells
Authors: Tao M. , Han Xiaofei , Han Kunhee
Published: February 2010

Solution-based doping methods are particularly suitable for low-cost, high-throughput and large-area processing of next-generation solar cells. In this paper, we review our recent progress in n-type doping of metal oxides during electrochemical deposition of these materials, including ZnO and Cu2O. For naturally n-type ZnO, n-type doping is achieved by substituting the cation (Zn) with a group III element (Al or Ga). In naturally p-type Cu2O, n-type doping is realized by substituting the anion (O) with a halogen (Cl or Br). The latter is of particular interest since it is in principle a universal n-type doping technique for all chalcogenides, while cation substitution has to be worked out on a case-by-case basis depending on the cation valence. In both cases, the doping mechanism is believed to be co-precipitation of either ZnO with dopant oxide (Al2O3 or Ga2O3) or Cu2O with Cu halide (CuCl or CuBr). Several 3rd-generation concepts are enabled by these solution-based doping methods, including 1) a radial p-n junction in chalcogenide nanowires for enhanced charge separation at the organic/inorganic interface and 2) a 3-dimentional p-n junction through chalcogenide nanowires as a new cell architecture for next-generation inorganic solar cells.
Effects of Substrate Orientation on Photovoltaic Performance of InGaAs Solar Cells
Authors: Tseng Ming-Chun , Horng Ray-Hua , Tsai Y. L. , Lin Snin-Nan , Wuu Dong-Sing , Wu Chih-Hung , Chao Chih-Kang , Yu H. H.
Published: February 2010

To investigate substrate orientation effect on the solar cell efficiency, In0.16Ga0.84As solar cells were grown on GaAs substrates with different miscut angles by metalorganic chemical vapor deposition. It was found that a p-n In0.16Ga0.84As solar cell grown on a 2°-off GaAs substrate exhibits better conversion efficiency than that grown on a 15°-off GaAs substrate. The poor performance of the 15°-off In0.16Ga0.84As solar cell could be attributed to the formation of high-density misfit dislocations through strain relaxation, which reduces minority carrier lifetime. The conversion efficiency of a 15°-off In0.16Ga0.84As solar cell could be improved by using a p-i-n structure. With the employment of the p-i-n structure design, a 15°-off In0.16Ga0.84As solar cell was demonstrated to show the conversion efficiency close to or even better than that of a 2°-off In0.16Ga0.84As solar cell with the same structure.
Carbon Nanotube Electrode for Iodide/Tri-Iodide Ion Redox Reaction in Dye Sensitized Solar Cell
Authors: Topon Ong-On , Inaguma Masayasu , Matsumoto Daisuke , Naoe Kunihiro , Tanabe Nobuo
Published: February 2010

Carbon nanotubes (CNTs) were used as a counter electrode of a dye sensitized solar cell (DSC) instead of a Pt counter electrode. The CNT electrodes were fabricated by growing CNTs on metal substrates by microwave plasma enhanced chemical vapor deposition (MPCVD). The size and the amount of CNTs that varied with the microwave power of MPCVD improve the electrochemical characteristics of the CNT electrode which is superior to that of Pt counter electrode. The conversion efficiency of DSCs with the CNT counter electrodes was comparable to that with the Pt counter electrode taking into account of the incident light availability. This study suggests that the CNT counter electrode directly grown on metal substrate be promising to accomplish the high energy conversion efficiency of DSC.
N-Type Doping in Electrodeposited Cu2O by Cu Diffusion
Authors: Han Kunhee , Tao M.
Published: February 2010

Cuprous oxide (Cu2O) is naturally p-type due to a high concentration of Cu vacancies. N-type doping of Cu2O by diffusing Cu atoms into Cu2O is proposed and demonstrated. It is suggested that Cu diffusion in Cu2O annihilates Cu vacancies, leading to Cu interstitials and/or O vacancies which are responsible for the n-type conductivity. The effect of Cu diffusion on structural and electrical properties of Cu2O is investigated in the temperature range of 100~400°C. The resistivity of Cu-doped Cu2O sharply decreases at 350°C and the lowest resistivity of 28 Ω-cm is obtained at annealing temperature of 400°C. A diffusion coefficient of 1.91×10-16 m2/sec is extracted at 325°C. Photocurrent measurements confirm that Cu-doped Cu2O is indeed n-type.
Solvent-Free ZnO Dye-Sensitised Solar Cells
Authors: Guillén Elena , Idígoras Jesús , Anta Juan A.
Published: February 2010

In this work we investigate the performance of Dye-Sensitized Solar Cells based on commercial nanostructured zinc oxide combined with imidazolium-based room temperature ionic liquid electrolytes. We have looked at the influence of the iodide concentration and the effect of common additives such as lithium ions and tert-butylpiridine. The crucial role of the ionic transport and recombination losses are thoroughly studied by impedance spectroscopy. A maximum photoconversion efficiency of 3.4% at 1 sun illumination has been obtained for cells of 0.64 cm2 active area with the best performing compositions and N719 dye as sensitizer. Diffusion limitations due to slow transport processes are analyzed and discussed. An indoline derivative named D149 is also used as sensitizer and its performance with solvent free electrolyte is analyzed
Nanostructured TiO2 Photoelectrodes for Dye Sensitized Solar Cells
Authors: Turkevych Ivan , Hara Koujirou , Kondo Michio
Published: February 2010

A new type of nanostructured TiO2 photoelectrode prepared by glancing angle deposition and oxidation (GLADOX) has been used to construct a dye sensitized solar cell. The photoelectrode consisted of small TiO2 nanotubes arranged in shells around long central cores that ensure connection of these nanotubes to the substrate. The brush-type morphology provides both the high surface area available for dye absorption and direct path for generated carriers. The overall performance of the brush-type photoelectrodes was comparable to the performance of the conventional nanoparticulate DSSC of the same thickness. However, brush-type morphology has a potential advantage over the nanoparticulate one due to improved transport properties, which allows maximization of the light absorption by increasing the thickness of the photoelectrode.
Pattern Formation in Electrodeposited Silver-Cadmium Alloys
Authors: Dobrovolska Tsvetina , Krastev Ivan , Zielonka Andreas
Published: February 2010

Electrochemical instabilities and potential oscillations with very high amplitude of up to about 800 mV are observed, which are connected with the simultaneous deposition of different phases of the alloy and intensive hydrogen evolution. The dependence of the potential oscillations on the electrolysis conditions is shown and discussed. Wide variety of spatio-temporal structures can be observed during electrodeposition of silver-cadmium alloys. The conclusion is made that the structures are possibly formed by periodical deposition of pure cadmium phase and very well oriented Cd3Ag phase.
Ionothermal Synthesis and Electrochemical Characterization of Nanostructured Lithium Manganese Phosphates
Authors: Barpanda Prabeer , Recham Nadir , Djellab Karim , Boulineau Adrien , Armand Michel , Tarascon Jean-Marie
Published: February 2010

Nanostructured LiMnPO4 was synthesized via a low temperature ionothermal synthesis route using various ionic liquids as reacting media. After due optimization of different processing parameters, LiMnPO4 of varied size and morphology were processed at temperature as low as 200-250{degree sign}C. Further, a modified ionothermal synthesis using a mixture of ionic liquid with propanediols was performed to yield platelet-shaped nanoscale LiMnPO4. The structure, morphology and electrochemical properties of these LiMnPO4 have been reported showing reversible capacity of 95 mAh/g with good cycling stability. This study shows the versatility and novelty of ionothermal synthesis method to tailor the size, orientation and morphology of olivine-LiMnPO4.
Fast and Low-cost Synthesis of LiFePO4/C Composites using Fe3+ Precursor
Authors: Kosova Nina , Devyatkina Evgeniya , Petrov Sergei
Published: February 2010

LiFePO4 and LiFePO4/C composites were prepared by mechanical activation process using Fe3+ precursor (Fe2O3) in comparison with Fe2+ precursor (FeC2O4•2H2O). The reaction mechanism, phase composition, particle size and electrochemical performance of as-prepared materials were examined by thermal analysis, X-ray diffraction, Mössbauer spectroscopy, SEM, TEM, and galvanostatic cycling. The LiFePO4/C composites were prepared by pyrolysis of suitable organic compounds during synthesis and by in situ incorporation of carbon powder. It has been shown that using carbothermal method, a phase-homogeneous nanosized LiFePO4 is formed at temperatures ≥700°C with specific discharge capacity ~150 mAh/g at C/10 rate.
Voltammetry of Vinblastine Sulfate in Acetonitrile
Authors: Haque Inam U. , Saba Hina
Published: February 2010

Voltammetry of vinblastine sulfate was carried out in acetonitrile containing 0.2 M of sodium perchlorate. The studies were done when 21.4 mM pyridine was present in the above background solution. Vinblastine sulfate gave a single anodic peak representing irreversible electrochemical oxidation, as shown in both cases. Although, the behavior of vinblastine sulfate was almost comparable in the presence/absence of pyridine. However, the studies carried in the absence of pyridine were more significant.
Electrocatalytic Fluoroalkylation of Olefins
Authors: Mikhaylov Dmitry Y. , Budnikova Yulia H. , Gryaznova Tatyana , Sinyashin Oleg G.
Published: February 2010

An efficient method of incorporating fluoroalkyl chains into carbon-carbon double bonds via electrocatalysis is described. Organonickel complexes stabilized by various N,N-ligands play a key role in this process. Ni(I)L is an active form of the catalyst according to cyclic voltammetry.
Polysulfone-composed Alkaline Anion Exchange Membrane for Improved Ionic Conductivity
Authors: Xie Dong , Wang Guigui , Weng Yiming , Chu Deryn , Chen Rongrong
Published: February 2010

Alkaline anion exchange membranes of high ionic conductivities were developed from polysulfone. The effects of temperature and time on chloromethylation of the polymer were investigated and the chloromethylation was optimized. Different approaches for quaternization of the synthesized chloromethylated polymer were studied. The results show that both temperature and time exhibited significant impacts on chloromethylation and gelation. Using an appropriate quaternization approach could significantly improve the ionic conductivity and also could optimize the conductivity of the membrane even though the accessible functional chloromethyl groups were limited. The developed AAEM showed the ionic conductivity up to 3.1 x 10-2 S/cm at room temperature. Increasing temperature increased the ionic conductivity up to 7.33 x 10-2 S/cm.