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This study concerns the three-dimensional hybrid nanofluid flow and heat transfer due to a deformable (stretching/shrinking) plate with power-law velocity and orthogonal surface shear. The flow due to the shrinking sheet is maintained with the imposition of wall mass suction. The effect of adding Cu and Al2O3 nanoparticles are represented by a homogeneous mixture model with the modified thermophysical properties. Two types of thermophysical properties for hybrid nanofluids are discussed and compared in this interesting work. The three-dimensional model is then, reduced into a relevant set of ordinary differential equations using similarity transformation. The results are generated using the bvp4c solver and presented in the tables and graphs. Duality of solutions are observed in both stretching and shrinking regions, however, only the first solution is proved to be stable and realistic. Surprisingly, the heat transfer rate augments when the power law velocity is used. The hybrid nanofluid with an upsurge of copper volume fraction also reduces the rate of heat transfer.

An improved semi-analytical method for calculating the reliability of 3D slopes with spatially varying shear strength parameters is proposed. The response of an existing semi-analytical method has been compared with that of the computationally more intensive, but more general, random finite element method (RFEM), demonstrating that the simpler method underestimates the failure probability. An alternative relationship for the expected failure length and two correction factors are proposed, which modify the original formulation of the simpler method. The proposed approach gives substantially improved results that compare favourably with those obtained by RFEM, and therefore provides a more accurate simplified solution.

Purpose High-dose-rate, multicatheter interstitial brachytherapy is technically complex and operator-dependent, requiring lengthy training and specialized skills. Furthermore, until the advent of contouring on computerized tomography (CT) images, difficulties existed in locating the target volume precisely. The present article reports the results of a study that aimed at producing and validating a 3D-printed template to aid in target volume localization for multicatheter interstitial brachytherapy in patients with breast cancer. Methods and Materials Thirteen patients, candidates for accelerated partial breast irradiation or boost, were enrolled in the study. The target volume was defined on CT slices, and a template with empty spaces corresponding to the target volume projection on the patient's skin was produced by a 3D printer. The procedure was compared with the standard method followed in our center (1) visually, by assessing overlap between the target volume projections on the patient's skin, (2) by X-ray findings, and (3) by intraclass correlation coefficient. Results Visual assessment and X-ray findings showed the 3D-printed target volume always fell within the standard volume in all 13 patients. The intraclass correlation coefficient indicated moderate agreement for both the medial and the lateral skin projections. Conclusions The 3-D printed templates constitute a quick, easy, and reliable method to localize the target volume for high-dose-rate interstitial multicathether brachytherapy in patients with breast cancer and can safely be used in clinical practice.

Three dimensional (3-D) elasticity solution is presented for simply supported functionally graded (FG) material plate by using a semi analytical approach . Formulation is based on solution of a two-point boundary value problem (BVP) governed by a set of coupled first order ordinary differential equations (ODEs) through thickness of plate. Fourth-order Runge–Kutta algorithm is used for numerical integration of these ODEs. A comprehensive comparison of the present formulation with other 3-D elasticity approaches available in the literature is also attempted. The proposed semi-analytical model is very simple, efficient and highly accurate. Both displacements and stresses are evaluated simultaneously with the same degree of accuracy which is the main feature of the present development.

A numerical study on the structure of the laminar premixed flames established on perforated plate burners is performed. Three dimensional numerical simulations are performed on different perforated plate geometries, under various operating conditions, using methane reaction mechanism consisting 36 species and 253 reactions. The comparison of numerical results of inline and staggered configurations of perforated plate burner models show that the flame interaction has significant role in the structure and stabilization of perforated burner flame. The flame structure, flame height and the standoff distances are studied for both inline and staggered configurations at fuel lean and rich conditions. The flame standoff distance and the flame height found to be higher for staggered configuration in comparison to the inline configuration. The flame structure is studied for different hole-to-hole distances. The numerical results show an increase in flame base curvature with an increase in hole-to-hole distance for both inline and staggered configurations. The flame thickness reduces with an increase in hole-to-hole distance for both inline and staggered cases. The effect of recirculation and flame base curvature causes the flame base to get stabilized at a higher distance in staggered configuration in comparison to the inline configuration.

Graphical Abstract Unlabelled image, This study investigated the formulation mechanism of microspheres via internal surfactant distribution. Eudragit L100 based microspheres loaded with bovine serum albumin were prepared by solid in oil in oil emulsion solvent evaporation method using acetone and liquid paraffin system containing sucrose stearate as a surfactant. The fabricated microspheres were evaluated for encapsulation efficiency, particle size, production yield, and in vitro release characteristics. The internal structures of microspheres were characterized using synchrotron radiation X-ray microcomputed tomography (SR-µCT). The enhanced contrast made the sucrose stearate distinguished from Eudragit to have its three dimensional (3D) distribution. Results indicated that the content and concentration determined the state of sucrose stearate and had significant influences on the release kinetics of protein. The dispersity of sucrose stearate was the primary factor that controlled the structure of the microspheres and further affected the encapsulation efficiency, effective drug loading, as well as in vitro release behavior. In conclusion, the 3D internal distribution of surfactant in microspheres and its effects on protein release behaviors have been revealed for the first time. The highly resolved 3D architecture provides new evidence for the deep understanding of the microsphere formation mechanism.

Purpose: To assess the accuracy and reproducibility of 3D-cine k-adaptative-t-autocalibrating reconstruction for cartesian sampling (3D cine kat-ARC) for quantification of biventricular volumes, ejection fraction and LV mass in clinical practice. Method: 74 patients underwent cardiac magnetic resonance for clinical indications. In the whole population 3D cine kat-ARC and 2D cine bSSFP images were acquired on short axis view. Subsequently, the population was divided in three subgroups (dilated, hypetrophic, other phenotypes). Two experienced observers performed analysis of volumes, biventricular function and left ventricular mass in the overall population and subgroups using an off-line workstation. Statistical analysis was performed using Student's t-test, linear regression and Bland-Altman plot, correlation coefficient η2 and the intraclass correlation coefficient (ICC). A cut-off value of p < 0.05 was considered statistically significant. Results: Biventricular volumes, function and left ventricular mass evaluated with 3D cine kat-ARC sequences did not show any significant difference compared to 2D bSSFP sequences in the overall population (p > 0.05). Bland-Altman analysis showed limited bias and narrow limits of the agreement for all measurements in overall population. Subgroup analysis showed a statistically significant difference (p = 0.04) for left ventricular ejection fraction (LVEF) in patients with a dilated phenotype; showing a minimum overestimation tendency for 3D cine kat ARC (2D cine bSSFP LVEF = 46.44 ± 15.83% vs 3D cine kat-ARC LVEF = 48.36 ± 16.50 %). Conclusions: 3D cine kat-ARC 3D sequences allow an accurate evaluation of biventricular volumes and function in a single breath hold.

Heat extraction by cold water circulation disturbs the thermo-chemical equilibrium of a geothermal reservoir, activating the dissolution/precipitation of minerals in the fractures. Calcite being a more reactive mineral than other rock minerals composing the earth curst, we investigate the permeability alteration during geothermal heat production from carbonate reservoirs. In this study the simulations are performed using the code FEHM with coupled thermo-hydro-chemical (THC) capabilities for a three dimensional domain. The computational domain consists of a single fracture connecting the injection and production wells. For reactive alteration of aperture, the model considers that the kinetics of dissolution/precipitation is coupled to the equilibrium interactions among the aqueous species/ions. The reaction rate predominantly depends on the temperature dependent solubility and advective-dispersive solute transport in the fracture. Due to the nonuniform flow fields resulting from injection and production, the coupled thermo-hydro-chemical processes initiate significant variation of the aperture alteration rate over the fracture. We have considered different operating conditions such as different mass injection rate, injection temperature and concentration of minerals. Our simulations show that dissolution and precipitation can occur simultaneously at different locations in fracture. Furthermore the reaction rate varies with time and the reaction rate can also switch between dissolution and precipitation. To illustrate this interesting behavior, the variations of shape and size of zero reaction rate contours with time are shown. An interesting outcome is a non-monotonic evolution of the overall transmissivity between the wells. The alteration of overall transmissivity largely depends on the concentration of mineral in the injected water with respect to the solubility at the initial fracture temperature. For both dissolution and precipitation controlled cases, the rapid changes in transmissivity provide challenges for maintaining circulation of water at constant mass flow rate. � 2013 Elsevier Ltd.

This paper presents direct numerical simulations (DNS) of fully developed turbulent liquid-metal flow in a circular duct entering a magnetic field. The case of a magnetohydrodynamic flow leaving a strong magnetic field has been extensively studied experimentally and numerically owing to its similarity to typical flow configurations appearing in liquid metal blankets of nuclear fusion reactors. Although also relevant to the design of fusion reactor blankets, the flow entering the fringing field of a magnet remains unexplored because its high intricacy precludes any simplification of the governing equations. Indeed, the complexity of the magnetohydrodynamic-turbulence interaction can only be analysed by direct numerical simulations or experiments. With that purpose, this paper addresses the case of a fully developed turbulent flow (Re τ ≈ 520) entering low, intermediate and strong magnetic fields under electrically insulating and poorly conducting walls by means of three-dimensional direct numerical simulations. Purely hydrodynamic computations (without the effect of the magnetic field) reveal an excellent agreement against previous experimental and numerical results. Current MHD results provide a very detailed information of the turbulence decay and reveal new three-dimensional features related to liquid-metal flow entering strong increasing magnetic fields, such as flow instabilities due to the effect of the Lorentz forces within the fringing region at high Ha numbers. © 2013 Elsevier B.V. © 2013 Published by Elsevier B.V. 88 3108 3124 3108-3124

Sixteen propellant formulations based on ammonium perchlorate (AP), hydroxyl-terminated polybutadiene, and aluminium particles have been tested for size distribution of aluminium agglomerates emerging from their burning surface. The formulations are based on a bimodal size distribution of AP particles. Ten of the formulations exhibit one or two plateaus/mesa in their burning rate variation with pressure (zero/negative pressure exponent of burning rate). The relevant formulation variables, namely, coarse and fine AP sizes and coarse-to-fine ratio, aluminium size and content, and two different curing agents, have been varied. Tests are performed in the 1-10 MPa pressure range. A direct correlation between burning rate and agglomerate size exists for propellants with normal burning rate trends but a neutral or inverse correlation is observed for those exhibiting plateau burning behaviour. Larger the parent aluminium size, lesser the agglomeration, as expected; but the effect of aluminium content is non-monotonic. The coarse AP size influences the aluminium agglomerate size as expected from the pocket model regardless of plateau burning effects. The agglomerate size decreases with increase in fine AP size, however. A computer model developed earlier at this laboratory for prediction of aluminium agglomerates based on three-dimensional packing of particles and deduction of AP particles with attached leading edge diffusion flames is applied to the present formulations. The model under-predicts the agglomerate size, only marginally for propellants that do not exhibit plateau burning rate trends, but substantially, otherwise. This is because it does not take into account effects of binder melt flow and is independent of the curing agent of the binder. � 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Multiple frame digital fringe projection technique is widely used for measuring the 3-D surface shape. In dynamic situations single frame analysis techniques are desirable. In this paper we discuss a Hilbert transform based single-frame analysis. Hilbert transformation method requires only one fringe pattern for the extraction of phase reducing the calculation time. The method is easy to implement, and it is capable of conducting automated measurements at video frame rate. The application of the proposed method for curved surfaces is emphasized. A few experimental results are presented. � 2011 Elsevier GmbH. All rights reserved.

The response of bridges subject to fire is an under researched topic despite the number of bridge failures caused by fire. Since available data shows that steel girder bridges are especially vulnerable to fire, this paper delves into their fire response by analyzing with a 3D numerical model the response of a typical bridge of 12.20 m span length. A parametric study is performed considering: (1) two possibilities for the axial restraint of the bridge deck, (2) four types of structural steel for the girders (carbon steel and stainless steel grades 1.4301, 1.4401, and 1.4462), (3) three different constitutive models for carbon steel, (4) four live loads, and (5) two alternative fire loads (the hydrocarbon fire defined by Eurocode 1 and a fire corresponding to a real fire event). Results show that restraint to deck expansion coming from an adjacent span or abutment should be considered in the numerical model. In addition, times to collapse are very small when the bridge girders are built with carbon steel (between 8.5 and 18 min) but they can almost double if stainless steel is used for the girders. Therefore, stainless steel is a material to consider for steel girder bridges in a high fire risk situation, especially if the bridge is located in a corrosive environment and its aesthetics deserves special attention. The methodology developed in this paper and the results obtained are useful for researchers and practitioners interested in developing and applying a performance-based approach for the design of bridges against fire. © 2012 Elsevier Ltd. All rights reserved., Funding for this research has been provided to Dr. Paya-Zaforteza by the Spanish Ministry of Education (contract number EX-2008-0669 of the Program for Postdoctoral Stays), the Spanish Ministry of Economy and Competitiveness (research project BIA 2011-27104) and the Universitat Politecnica de Valencia (Research and Development Support Program PAID-06-11). Funding has also been provided to Dr. Maria Garlock by the National Science Foundation (NSF) under award number CMMI-1068252. All opinions expressed in this paper are the authors' and do not necessarily reflect the policies and views of the sponsors.

We present a detailed magnetic critical behavior study of Fe 2CrAl Heusler alloy, for the first time, with rigorous analysis of high precision magnetization data obtained over the critical temperature region. Our studies confirm that B2 type site-disordered in Fe 2CrAl alloy exhibits long-range ferromagnetic order below a well defined Curie temperature (T=208 K). Though the nature of this transition is found to be of second order, the estimated critical exponents ?=0.42, ?=1.356 and ?=4.25, are in between the theoretically predicted values for three-dimensional Heisenberg and mean-field interaction models. However, it is noteworthy that the scaling relations are obeyed indicating renormalization of interactions around the Curie temperature (T C), where magnetization data collapse into two separate branches, above and below T C. This conclusively shows that calculated critical exponents as well as critical temperature are unambiguous and intrinsic to the system. However, magnetization vs temperature data shows another magnetic transition (at T=313 K) above the Curie temperature. It is shown that the short range magnetic correlation exist even beyond T C with cluster moment ?10 2 ? B. This is attributed to a site disorder which results in formation of Cr clusters with short range ferromagnetic order. � 2011 Elsevier B.V. All rights reserved.

Statistical-mechanical, 3D-RISM-KH molecular theory of solvation is an integral equation theory of molecular liquids capable of describing, from the first principles, solvation structure and thermodynamics in complex nanoscale systems. The 3D-RISM-KH theory accurately yields the solvation structure for biomolecular systems as large as chaperonins and ion channels. It predicts 3D maps of ligand binding affinity at once without using empirical scoring functions, and has significant potential for computer-aided drug design. Recently, the 3D-RISM-KH theory was coupled with MD simulations by contracting solvent degrees of freedom to treat solvated biomolecules, and the MD/3D-RISM-KH multiscale method was implemented in the Amber molecular dynamics package [T. Luchko et al., 2010, [29]]. The MD/3D-RISM-KH method allows one to study biomolecular processes on extremely long timescales, as the statistics of rare solvent and ligand events is accounted for analytically. We further replaced the MM/GB(PB)SA post-processing which evaluates the free energy by empirical treatment of non-polar solvation effects with the MM/3D-RISM-KH method which employs 3D-RISM-KH to evaluate the solvation thermodynamics. In this paper, we briefly review the 3D-RISM-KH theory as well as the MD/3D-RISM-KH multiscale method implemented in the Amber package. We illustrate the MM/3D-RISM-KH method on binding of thiamine (vitamin of group B) to extracytoplasmic thiamine-binding lipoprotein MG289, and on the microscopic solvation properties of the bacterial Gloeobacter violaceus pentameric ligand-gated ion channel (GLIC) homologue. © 2011 Published by Elsevier B.V. All rights reserved.

[EN] This paper describes the methodology followed to perform a co-simulation between 1D (OpenWAM) and 3D (FLUENT) CFD codes. The Method of Characteristics (MoC) has been chosen to transfer the information between the two domains by properly updating the boundary condition at the shared interface. A short explanation of the MoC is provided, including the modifications needed by the Riemann invariants when dealing with non-homentropic flow. The implementation of the coupling is explained, focusing on the particular approach required by FLUENT in order to obtain the Riemann invariants. Two validation tests have been performed. The Sod's problem has been used to test the numerical accuracy of the coupling methodology. On the other hand, an impulse test rig configuration has been simulated to show the potential capability of a co-simulation in terms of reducing the computational cost. In both cases a good agreement in the solution is found. © 2010 Elsevier Ltd., Roberto Navarro is indebted to the Universidad Politecnica de Valencia for its support through Grant Beca de Excelencia 2009. PAID-09-09.

We propose a method for rapidly classifying surface reflectance directly from the output of spatio-temporal filters applied to an image sequence of rotating objects. Using image data from only a single frame, we compute histograms of image velocities and classify these as being generated by a specular or a diffusely reflecting object. Exploiting characteristics of material-specific image velocities we show that our classification approach can predict the reflectance of novel 3D objects, as well as human perception. © 2010 Elsevier Ltd. All rights reserved.

Transient simulation of retinal laser irradiation is performed for a square array comprising 3 � 3 uniformly distributed spots under sequential and simultaneous mode. A finite volume formulation of the Pennes bio-heat transfer model is employed as the governing equation to generate the temperature distribution within the eye domain. Temperature distribution developed due to laser power of 0.2 W/spot and time duration of 100 ms/spot is used to compare the merits of sequential and simultaneous irradiation of spots. Simultaneous mode is preferred when the time of surgery is limited, with possible excess heating in the inter-spot retinal regions. The inter-spot spacing D is also varied between one diameter and one and half diameter of the spot size (diameter) to evaluate the safe placement of consecutive spots. D ? 0.75 mm can be considered as the optimum spot distance for non-interference due to excess heating. Effect of pulsation of incident laser power is observed to favorably reduce the average temperature of the irradiated regions of the retina toward photocoagulation temperature. � 2011 Elsevier Masson SAS. All rights reserved.

In this study a special three-dimensional interface element has been formulated for stress and displacement analyses in bonded joint between two adjacent plate bending and brick elements. Interface element has 16 nodes with 5 degrees of freedom in each node adjacent to plate bending element and 3 D.O.F in each node adjacent to brick elements. The interface element has ability to transfer three translations from each side of interface element and two more rotations in the side adjacent to the plate element. Stiffness matrix of this element was formulated and implemented in three dimensional finite element code. Using experimental and numerical work of strengthened RC concrete beams carried out by researchers, application of this element including variation of deflection, slip between plates and bricks, normal and shear stresses distributions in FRP plates have been verified. The results show, that this interface element is effective and can be used for structural components with this type of interface element.

This paper presents an algorithm for generating the Interior Medial Axis Transform (iMAT) of 3D objects with free-form boundaries. The algorithm proposed uses the exact representation of the part and generates an approximate rational spline description of the iMAT. The algorithm generates the iMAT by a tracing technique that marches along the object's boundary. The level of approximation is controlled by the choice of the step size in the tracing procedure. Criteria based on distance and local curvature of boundary entities are used to identify the junction points and the search for these junction points is done in an efficient way. The algorithm works for multiply-connected objects as well. Results of the implementation are provided. (C) 2010 Elsevier Ltd. All rights reserved.

In this paper, a novel, simple, yet useful, generalized plane strain finite element formulation for the analysis of piezocomposite beam has been presented. This finite element formulation is a 2D formulation with improved accuracy in predicting the buckling behavior of the piezocomposite beam when compared to the conventional 2D piezofinite element formulation. Though the present formulation has the same computational cost as of a conventional 2D piezofinite element formulation, the buckling results predicted by this formulation are close to 3D piezofinite element formulation. This generalized plane strain formulation is similar to the plane strain formulation that reduces a 3D stressstrain relation to 2D stressstrain relation and does not include out of plane degrees of freedom, which is included in most of the formulations available for generalized plane strain. In the present formulation, the reduced 2D stressstrain relationship incorporates the effect of allowed/applied strain ?0 in the third direction (the direction that is not included in the 2D FE model). This paper reveals an important concept that the variation of buckling results predicted by plane stress, plane strain and 3D piezofinite element formulations for a piezocomposite beam varies very significantly in contrast to the elastic finite element formulation (or closed circuit condition of a piezofinite element formulation) where there are no such significant variations. � 2010 Elsevier B.V.

Measurements of the internal geometry of a carbon fiber non-crimp 3D orthogonal woven composite are presented, including: waviness of the yarns, cross sections of the yarns, dimensions of the yarn cross sections, and local fiber volume fraction. The measured waviness of warp and fill yarns are well below 0.1%, which shows that the fabric termed here “non-crimp” has nearly straight in-plane fibers as-produced, and this feature is maintained after going through all steps of fabric handling and composite manufacturing. The variability of dimensions of the yarns is in the range of 4–8% for warp and fill directions, while the variability of the yarn spacing is in the range of 3–4%. These variability parameters are lower than respective ranges of variability of the yarn waviness and the cross-sectional dimensions in typical carbon 2D weave and 3D interlock weave composites, which are also illustrated in this work for comparison.

A three dimensional, steady state, non-isothermal, single phase model was developed and simulations were carried out in order to find the effect of cathode channel dimensions (width, depth and height) on the performance of an air-breathing fuel cell. The model was solved using commercial CFD package Fluent (version 6.3). Separate user defined functions were written to solve the electrochemical equations and the water transport through the membrane along with the other governing equations. Analyses were carried out for three different channel widths (2, 4 and 6�mm), for three different channel depths (2, 6 and 10�mm) and for three different cell heights (15, 30 and 45�mm). Cell characteristics like current distribution, species distribution, oxygen mass transfer coefficient, cell temperature, cathode channel velocities and net water transport coefficients are reported. The results show that the cell performance improves with increase in cathode channel width, channel depth and with decrease in cell height. Maximum power density obtained was 240�mW/cm2 for a channel width of 4�mm and channel depth of 6�mm. When the channel depth was 2�mm the performance was limited mainly due to the resistance offered by the channel for the buoyancy induced flow. For channel depths higher than 2�mm, the diffusion resistance of the porous GDL also contributed significantly to limit the performance to low current densities. At low current densities the fuel cell is prone to flooding whereas at high current densities ohmic overpotential due to dehydration of the membrane significantly contributes to the overall voltage loss. � 2009 Elsevier Masson SAS. All rights reserved.

4D CAD models that integrate physical 3D elements with time, have been used to visualize construction processes in several projects worldwide. 4D models have been used and have been shown to have benefits over processes that span the entire lifecycle of a project such as collaboration with stakeholders, making design decisions, assessing project constructability, identifying spatial conflicts in construction and so on. Despite these benefits, several organizational and project-specific barriers have hindered the widespread adoption of 4D CAD. In order to reconcile the theoretical benefits of 4D models with the practical difficulties faced in implementation, there is an urgent need to explore the implementation of 4D models on construction sites as well as the perceptions of intended users/beneficiaries towards this implementation. This paper aims to address this need and contribute to our understanding of how 4D models must be introduced, positioned and implemented on construction sites, so as to maximize both their acceptability and their usefulness. We describe two 4D models of infrastructure projects and two 4D models of commercial projects that have been built and implemented. Through a process of structured and unstructured interviewing the paper gauges the response of project participants across various organizational levels on each of these projects as to the usefulness of 4D in project planning and control. Through qualitative and statistical analysis of the data we establish that 4D CAD is likely to be most beneficial in the project shaping or planning stage and in the construction stage. In the project shaping stage, 4D CAD is likely to be particularly useful in communicating construction plans and processes to clients, while during the construction phase, 4D CAD is likely to be particularly useful in comparing the constructability of work methods visually in order to detect conflicts or clashes, and as a visual tool for contractors, clients, subcontractors and vendors to review and plan project progress. Further, upper management and site workers are more likely to use and derive benefits from the visualization of processes using 4D given their lack of site related knowledge or skills, while construction professionals who are more construction-savvy are more likely to appreciate and benefit from the analytical and planning aids that 4D simulations provide during the construction phase. However, it is likely that despite these benefits 4D CAD models might not diffuse through the construction industry unless 4D modelling and analysis is integrated into existing project planning approaches. The paper concludes with a brief discussion on future 4D software development that seeks to bring about such integration and leverages the benefits of 4D CAD to bring about improved operational efficiencies on construction sites. � 2009 Elsevier B.V. All rights reserved.

Connectivity-Guided Adaptive Wavelet Transform based mesh compression framework is proposed. The transformation uses the connectivity information of the 3D model to exploit the inter-pixel correlations. Orthographic projection is used for converting the 3D mesh into a 2D image-like representation. The proposed conversion method does not change the connectivity among the vertices of the 3D model. There is a correlation between the pixels of the composed image due to the connectivity of the 3D mesh. The proposed wavelet transform uses an adaptive predictor that exploits the connectivity information of the 3D model. Known image compression tools cannot take advantage of the correlations between the samples. The wavelet transformed data is then encoded using a zero-tree wavelet based method. Since the encoder creates a hierarchical bitstream, the proposed technique is a progressive mesh compression technique. Experimental results show that the proposed method has a better rate distortion performance than MPEG-3DGC/MPEG-4 mesh coder. © 2009 Elsevier Inc. All rights reserved.

Effect of cathode design on the performance of an air-breathing fuel cell is studied using a three dimensional, non-isothermal, steady state and single phase model developed using commercial CFD software FLUENT (version 6.3). Performances of ducted (channel) and ribbed (planar) cathode designs are compared and the cell characteristics such as current density, species, temperature distributions, velocity and net water transport coefficient are presented. Peak power density obtained for the cell with ducted cathode is 205 m W/cm2, whereas with ribbed cathode it is 232 m W/cm2. The limiting current density of the cell with ribbed cathode (690 m A/cm2) is much higher than that of the cell with ducted cathode (430 m A/cm2). The performance curves as well as the cell characteristics show that the ribbed cathode design is a better configuration compared to ducted design. Cell orientation has a significant effect on the cell performance. Best performance is obtained when the cell is oriented vertically for both ribbed and ducted cathode designs. � 2009 Professor T. Nejat Veziroglu.

In this study, we propose an efficient algorithm for the evaluation of the particular solutions of three-dimensional inhomogeneous elliptic partial differential equations using radial basis functions. The collocation points are placed on concentric spheres and thus the resulting global matrix possesses a block circulant structure. This structure is exploited to develop an efficient matrix decomposition algorithm for the solution of the resulting system. Further savings in the matrix decomposition algorithm are obtained by the use of fast Fourier transforms. The proposed algorithm is used, in conjunction with the method of fundamental solutions for the solution of three-dimensional inhomogeneous elliptic boundary value problems. © 2009 Elsevier Ltd. All rights reserved. 33 12 1368 1373 Cited By :17

This Part 2 paper presents results of comparative experimental study of progressive damage in 2D and 3D woven glass/epoxy composites under in-plane tensile loading. As Part 1, this Part 2 work is focused on the comparison of in-plane tensile properties of two non-crimp single-ply 3D orthogonal weave E-glass fibre composites on one side and a laminate reinforced with four plies of E-glass plain weave on the other. The damage investigation methodology combines mechanical testing with acoustic emission registration (that provides damage initiation thresholds), progressive cracks observation on transparent samples, full-field surface strain mapping and cracks observation on micrographs, altogether enabling for a thorough characterisation of the local micro- and meso-damage modes of the studied composites. The obtained results demonstrate that the non-crimp 3D orthogonal woven composites have significantly higher in-plane strengths, failure strains and damage initiation thresholds than their 2D woven laminated counterpart. The growth of transverse cracks in the yarns of 3D composites is delayed, and they are less prone to a yarn-matrix interfacial crack formation and propagation. Delaminations developing between the plies of plain weave fabric in the laminate at certain load level never appear in the 3D woven single-ply composites. (C) 2009 Elsevier Ltd. All rights reserved. East-European PhD grant of K.U. Leuven Research Council (D.S. Ivanov) Department MTM

We report a simple and cost-effective double templating method for fabricating large-area three-dimensional metallic photonic crystals of controlled thickness. A self-assembled polystyrene opal was used as the first template to fabricate a silica inverse opal on a gold-coated glass substrate via sol-gel processing. Gold was subsequently infiltrated to the pores of the silica inverse opal using electrochemical deposition. A high-quality three-dimensional gold photonic crystal was obtained after removal of the secondary template (silica inverse opal). The effects of template sphere size and deposition current density on the gold growth rate, and the resulting morphology and growth mechanism of the gold opal, were investigated. � 2009 Elsevier B.V. All rights reserved.

International audience; We consider a quantum particle in an infinite square potential well of ℝn, n = 2; 3, subjected to a uniform electric field in space. Under the dipolar moment approximation, the wave function solves a PDE of Schrödinger type. We study the spectral controllability in finite time of the linearized system around the ground state. We characterize one necessary condition for spectral controllability in finite time (K al) if Ω is the bottom of the well, then for every eigenvalue λ of - ΔDΩ, the projections of the dipolar moment onto every (normalized) eigenvector associated to λ are linearly independent in ℝn. In 3D, our main result states that spectral controllability in finite time never holds for one-directional dipolar moment. The proof uses classical results from trigonometric moment theory and properties about the set of zeros of entire functions. In 2D, we first prove the existence of a minimal time Tmin(Ω) andgt; 0 for spectral controllability i.e., if T andgt; Tmin(Ω), one has spectral controllability in time T if condition (K al) holds true for (Ω) and, if T andlt; T min(Ω) and the dipolar moment is one-directional, then one does not have spectral controllability in time T. We next characterize a necessary and sufficient condition on the dipolar moment insuring that spectral controllability in time T andgt; Tmin(Ω) holds generically with respect to the domain. The proof relies on shape differentiation and a careful study of Dirichlet-to-Neumann operators associated to certain Helmholtz equations. ©2009 IEEE.

Al70Y16Ni10Co4 glassy powder was produced by mechanical alloying of elemental powder mixtures and the thermal stability as well as the crystallization kinetics was investigated using differential scanning calorimetry in both isochronal and isothermal modes. The isochronal and isothermal activation energies have a similar value (?280 kJ/mol). Similar activation energy was obtained for the process from the viscosity measurements. In addition, JMA analysis shows that the transformation is diffusion controlled three-dimensional process and the crystallization proceeds with increasing nucleation rate at annealing temperatures within the supercooled liquid region, while it proceeds with decreasing nucleation rate at temperatures below the glass transition temperature. Metal matrix composites were synthesized through powder metallurgy methods by hot extrusion of commercial 6061 Al alloy powder blended with different amounts of Al70Y16Ni10Co4 metallic glass reinforcement. The mechanical properties of the 6061 matrix are remarkably improved by the addition of the glass reinforcements. The ultimate compressive strength increases from 260 MPa for the 6061 alloy to 350 MPa for the composite with 50 vol.% of glassy phase. � 2008 Elsevier B.V. All rights reserved.

For seamless automation, computer-aided design and manufacturing activities have to be linked by computer-aided process planning (CAPP). An important subtask in CAPP is setup planning, in which a setup plan must be generated ideally from a given 3-D model of the component. In this paper, a hybrid approach that effectively uses volume subtraction and face adjacency graph is proposed to recognize manufacturing features from 3-D model data in STEP AP-203 format. The proposed feature recognition is generic in nature and is capable of recognizing intersecting features also with relative ease. The manufacturing features are clustered based on preferential base for machining and a setup sequence is obtained by alternative rating and ranking. Finally, locating and clamping for each setup are determined considering intermediate shapes of the workpiece. This setup planning method reduces the number of alternatives for evaluation and thereby the computational effort. � 2008 Elsevier Ltd. All rights reserved.

Experiments were carried out to study the effects of sample width on the early upward flame spread, when typically the heat release rate per unit width ( Q ˙ ′ ) is less than 30 kW/m. Samples of clear poly-methyl-methacrylate (PMMA) were 0.4 m high and 0.03 m thick, and width values of 0.025, 0.050, 0.1, 0.15, and 0.2 m were tested. A new processing method, based on wavelet decomposition, was developed to detect the pyrolysis front location from video recordings of the bubbling surface. Different propagation behaviours are observed depending on the slab width, w. For w⩾0.1 m, flame height, rate of spread (ros), and Q ˙ ′ are found to be width-independent. The flame seems to remain laminar during the entire spreading process and flame height measurements are found to be in good agreement with available literature data. For the narrower slabs (0.025 and 0.05 m), a transition from laminar to turbulent flame is observed, the value of Q ˙ ′ at which the transition occurs decreasing with the width of the slab. Moreover the spread rate decreases with the slab width as a result of reduction in flame height due to three-dimensional aerodynamic effects. For w=0.05 m, flame height decreases whereas Q ˙ ′ is not affected. This may be related to the lateral entrainment of air above the pyrolysis region. For w=0.025 m, three-dimensional effects extend to the burning region. A significant decrease in the heat release rate per unit width is then observed, which in turn leads to a reduction in flame height. This configuration, where the flame tip is very close to the pyrolysis front, is of particular interest for fire safety since it corresponds to near-critical conditions for flame spread.

International audience; This work deals with the modeling of a flood in an urban environment. Among the various types of urban flood events, it was decided to study specifically the severe surface flooding events, which take place in highly urbanized areas. This work concerns particularly the numerical resolution of the two-dimensional Saint Venant equations for the study of the propagation of flood through the crossroads in the city. A discontinuous finite-element space discretization with a second-order Runge-Kutta time discretization is used to solve the two-dimensional Saint Venant equations. The scheme is well suited to handle complicated geometries and requires a simple treatment of boundary conditions and source terms to obtain high-order accuracy. The explicit time integration, together with the use of orthogonal shape functions, makes the method for the investigated flows computationally more efficient than comparable second-order finite volume methods. The scheme is applied to several supercritical flows in crossroads, which are investigated by Mignot. The experimental results obtained by the author are used to verify the accuracy and the robustness of the method. The results obtained are compared to those obtained by a second-order finite volume method (Rubar20 (2D)) and by FLUENT (3D). A very good agreement between the numerical solution obtained by the Runge-Kutta discontinuous Galerkin (RKDG) method and the experimental measured data were found. The method is then able to simulate the flow patterns observed experimentally and able to predict well the water depths, the discharge distribution in the downstream branches of the crossroad and the location of the hydraulic jumps and other flow characteristics more than the other methods.

Numerical simulations of round, compressible, turbulent jets using the Shear Stress Transport (SST k – ω ) model have been carried out. The three-dimensional calculations have been done on a tetrahedral mesh with 0.9 million cells. Two jets, one cold and hot, have been simulated. The Mach number for both the cases is 0.75. Overall sound pressure levels (SPL) at far-field observer locations have been calculated using Ffowcs Williams–Hawkings equation. The numerical predictions have been compared with experimental results available in the literature. Axial and radial variation of the mean axial velocity, axial variation of u ′ u ′ ¯ 1 / 2 , v ′ v ′ ¯ 1 / 2 , radial variation of u ′ v ′ ¯ and overall SPL levels are compared. The potential core length is predicted well, but the predicted centerline velocity decay is faster than the measured value. The URANS calculations are not able to predict the absolute values for the overall SPL, but predict the trends reasonably well. The calculations predict the trends and absolute values of the variations of the spectral amplitude well for the aft receivers, but not for the forward receivers. Effect of chevrons on the noise from the jet is also investigated for cold and hot jets. In each case, two chevron taper angles, namely, 0° and 5° are considered. The latter nozzle produces the most significant modification to the baseline spectra and is less effective at high frequencies in abating the noise. The present calculations predict a reduction in the overall SPL for the chevron nozzle with 0° taper angle and a slight increase for chevron nozzle with 5° taper angle, for both cold and hot jets.

A Galerkin finite element method is developed for the two dimensional/three dimensional nonlinear time-dependent three-species Lotka–Volterra competition-diffusion equations on a bounded domain. The existence and uniqueness of the solution to the numerical formulation are proved. An error estimate for the numerical solution is obtained. Numerical computations are carried out to examine the expected orders of accuracy in the error estimates.

Equal channel angular pressing (ECAP) is currently being widely investigated because of its potential to produce ultra-fine grained microstructures in metals and alloys. A sound knowledge of the plastic deformation and strain distribution is necessary for understanding the relationships between strain inhomogeneity and geometry of die. Considerable research has been reported on finite element analysis of this process, assuming 2D plane strain condition. The 2D models are not suitable due to the component geometry, especially for workpiece with cylindrical cross-section. In the present work 3D simulation of ECAP process was carried out, using ABAQUS/Standard software, for different channel angles for a strain hardening aluminium alloy (AA6101). Strain inhomogeneity is presented and discussed for all cases. Pattern of variation of strain along some selected radial lines in steady-state zone is presented. � 2008 Elsevier B.V. All rights reserved.

In this study a combined computational model of a room with virtual thermal manikin with real dimensions and physiological shape was used to determine heat and mass transfer between human body and environment. Three dimensional fluid flow, temperature and moisture distribution, heat transfer (sensible and latent) between human body and ambient, radiation and convection heat transfer rates on human body surfaces, local and average convection coefficients and skin temperatures were calculated. The radiative heat transfer coefficient predicted for the whole-body was 4.6 W m(-2) K-1, closely matching the generally accepted whole-body value of 4.7 W m(-2) K-.(-1) Similarly, the whole-body natural convection coefficient for the manikin fell within the mid-range of previously published values at 3.8 W m(-2) K-1. Results of calculations were in agreement with available experimental and theoretical data in literature. (C) 2008 Elsevier Ltd. All rights reserved.

Currently, there is a focus on authentic tasks as the driving force for learning in integrated e-learning systems. This sets new criteria for instructional software, which should become much more flexible and allow for domain modeling and pedagogical modeling. A theoretical analysis and a survey (n = 37) amongst experienced developers show that current development methods are insufficient to develop such instructional software. New development methods such as ‘‘lean production’’ promise to satisfy the new criteria as they emphasize mass-customization by rigorously applying a pull-principle throughout the whole development process. However, a potential bottleneck is the lack of design languages to transfer the design outcomes to the production phase. Three building-block solutions are proposed to overcome this transition problem: (1) a 3D-model to support designers in stratifying, elaborating, and formalizing design documents, (2) instructional software templates to support designers in producing software themselves, and (3) an integrative approach to support designers in reusing learning objects. Keywords: Instructional software; Development; Training; Computer-based training; e-Learning; Competencybased learning

A multiscale methodology has been developed for modeling mechanical behavior of collagen fiber networks. The methodology addresses scale separation between the macroscopic, tissue-level scale and the microscopic, fiber-level scale. A three-dimensional, Galerkin finite-element model has been employed for the macroscopic scale, while the tissue microstructure is represented as a three-dimensional fibrillar network. The model was applied to a rectangular slab in uniaxial extension. A heterogeneous microstructure resulted in a non-uniform deformation field, and Poisson's ratio varied for networks with different alignments. The model was also specified and compared to published data relating microstructure to macroscopic behavior of collagen gels. © 2007 Elsevier B.V. All rights reserved. 196 2981 2990 2981-2990

The present experimental study is conducted to investigate the effect of horizontal production well in waterflooding when conventional vertical production well stops oil production. Laboratory experiments have been performed on three-dimensional sand pack models. In the waterflooding experiments, the horizontal production well is turned on after the complete extraction of oil from the vertical production well. The experimental results show that horizontal well increases the ultimate recovery by waterflooding significantly when oil production stops from the conventional vertical production well. Moreover, the position of the horizontal well either at top or bottom of the sand pack has negligible effect on ultimate oil recovery for the sand packs used., © Elsevier

Here we investigate the practical feasibility of performing soundfield reproduction throughout a three-dimensional area by controlling the acoustic pressure measured at the boundary surface of the volume in question. The main aim is to obtain quantitative data showing what performances a practical implementation of this strategy is likely to yield. In particular, the influence of two main limitations is studied, namely the spatial aliasing and the resonance problems occurring at the eigenfrequencies associated with the internal Dirichlet problem. The strategy studied is first approached by performing numerical simulations, and then in experiments involving active noise cancellation inside a sphere in an anechoic environment. The results show that noise can be efficiently cancelled everywhere inside the sphere in a wide frequency range, in the case of both pure tones and broadband noise, including cases where the wavelength is similar to the diameter of the sphere. Excellent agreement was observed between the results of the simulations and the measurements. This method can be expected to yield similar performances when it is used to reproduce soundfields., 28 pages de texte

In this article, static analysis of functionally graded, anisotropic and linear magneto-electro-elastic plates have been carried out by semi-analytical finite element method. A series solution is assumed in the plane of the plate and finite element procedure is adopted across the thickness of the plate such a way that the three-dimensional character of the solution is preserved. The finite element model is derived based on constitutive equation of piezomagnetic material accounting for coupling between elasticity, electric and magnetic effect. The present finite element is modeled with displacement components, electric potential and magnetic potential as nodal degree of freedom. The other fields are calculated by post-computation through constitutive equation. The functionally graded material is assumed to be exponential in the thickness direction. The numerical results obtained by the present model are in good agreement with available functionally graded three-dimensional exact benchmark solutions given by Pan and Han [Pan, E., Han, F., in press. Green’s function for transversely isotropic piezoelectric functionally graded multilayered half spaces. Int. J. Solids Struct.]. Numerical study includes the influence of the different exponential factor, magneto-electro-elastic properties and effect of mechanical and electric type of loading on induced magneto-electro-elastic fields. In addition further study has been carried out on non-homogeneous transversely isotropic FGM magneto-electro-elastic plate available in the literature [Chen, W.Q., Lee, K.Y., Ding, H.J., 2005. On free vibration of non-homogeneous transversely isotropic magneto-electro-elastic plates].

Morphological closing filters have been suggested in the literature for processing of profile and functional characterization. In the present work, an attempt is made to extend it to three-dimensional surfaces. Though a sphere is a logical extension of a circular structuring element, a doubly curved (toroidal) element is considered for establishing a reference surface representing waviness and form errors. By such an element, different filtering characteristics in the x and y-directions can be obtained. In this paper, transmission characteristics of morphological filters are presented first for theoretical surfaces. The reference surfaces are also obtained for the practical surfaces and further analyzed by random process techniques. ? 2005.

A simple C0isoparametric finite element formulation based on a shear deformable model of higher-order theory using a higher-order facet shell element is presented for the free vibration analysis of isotropic, orthotropic and layered anisotropic composite and sandwich laminates. This theory incorporates a realistic non-linear variation of displacements through the shell thickness, and eliminates the use of shear correction coefficients. The validity and efficiency of the present formulation is established by obtaining solutions to a wide range of problems and comparing them with the available three-dimensional closed-form and finite element solutions. In addition, other plate and shell solutions of different kind and available in the literature are also compiled and tabulated for the sake of completeness. The parametric effects of degree of orthotropy, length-to-thickness ratio, plate aspect ratio, number of layers and fibre orientation upon the frequencies and mode shapes are discussed., © Elsevier

Residual stresses due to welding have been estimated using a nine-noded degenerated shell element with assumed strains. It is well known that shell elements are capable of handling three-dimensional (3-D) configurations with less computational effort when compared to the full 3-D analysis. The temperature field in the entire weld domain has been calculated using a 3-D brick element. The temperature variation so obtained is utilised to find the distribution of the stress field using the concept of through-thickness integration. Thermal strains at individual Gauss points are calculated and the same are integrated to obtain the nodal loads. Thermo-elasto–plastic formulations using a von-Mises yield criterion with linear isotropic hardening has been employed. The formulations are validated with 2-D and 3-D experimental results available in the literature. It was established that this method can be used for estimating residual stresses in shell-like structures.

A new algorithm for fully automatic structured mesh generation is described. The algorithm is applicable equally to two-dimensional regions and three-dimensional surfaces and solids. The effectiveness of the algorithm is illustrated with several examples. Copyright ? 1996 Elsevier Science Ltd.

An investigation to study the behaviour of reinforced concrete four-pile caps by three-dimensional nonlinear finite element analysis is presented. Four-pile caps having different reinforcement layouts were considered. Eight-noded isoparametric brick elements with incompatible modes and two-noded three-dimensional truss elements were used to model the concrete and steel, respectively, of the pile caps. The steel elements were assumed to lie on the edges of the brick elements. The smeared cracking model was employed for modelling cracks during the analysis. The nonlinear components, such as multiaxial compressive behaviour of concrete, including strain softening, cracking of concrete and yielding of steel reinforcement, were considered. The load deflection characteristics, the strains in the reinforcement, the crack patterns and the ultimate loads are presented herein. Some of the theoretical results are compared with those obtained from experiments carried out on reinforced concrete pile cap specimens. ? 1995.

This paper describes the cutter path planning and cutter interference (gouging) analysis algorithms developed to generate optimal tool path for manufacturing sculptured surfaces on three axes CNC machine tools. Cutter path planning algorithm approximates the parametric curves on three dimensional surfaces by a sequence of straight line segments and generates optimal tool paths by minimizing the number of interpolation points while keeping the path deviations within the specified tolerances. Cutter interference analysis algorithm checks for the self intersection of an offset surface and determines the self-intersection curve. The tool path is then planned over the cutter contact (CC) surface after removing the CC data that lies inside the self-intersection curve. Finally, the effectiveness of these algorithms is demonstrated by implementing them in CAD/CAM system. ? 1995.

The vibration and damping analysis of orthotropic cylindrical shells with a constrained viscoelastic core is carried out by using a finite element based on a discrete layer theory. The material damping of the facings is also included in the analysis. Results are represented for different geometric and material properties of the shell. The data and trends presented for various cases could be useful for designers in choosing damping treatments for composite shells. ? 1994 Academic Press. All rights reserved.

Cataloged from PDF version of article. Inference of 3-D shape from 2-D contours in a single image is an important problem in machine vision. Often, techniques to solve this problem examine each surface in the scene separately whereas our perception of their shapes clearly depends on the interplay between them as well. In this paper, we describe a technique that attempts to recover the shapes of all the surfaces of an object simultaneously, though it is limited to objects made of zero-Gaussian curvature surfaces. Our technique is based on an analysis of three kinds of symmetries defined in the paper and the constraints that derive from them, and from other boundaries. This technique uses some of the constraints developed in an earlier paper that was limited to examining a zero-Gaussian curvature surface cut by parallel planes. This restriction has been removed here and the constraints have been reformulated to allow integration of constraints from all the neighboring surfaces. Results on some complex examples are shown.