van der Vegt, Jacobus J.W.; Izsak, F.; Bokhove, Onno
2007-01-01
Abstract. A detailed a priori error estimate is provided for a continuous-discontinuous Galerkin ��?nite element method for the generalized 2D vorticity dynamics equations. These equations describe several types of geophysical ﬂows, including the Euler equations. The algorithm consists of a
Activated sludge model No. 2d, ASM2d
DEFF Research Database (Denmark)
Henze, M.
1999-01-01
The Activated Sludge Model No. 2d (ASM2d) presents a model for biological phosphorus removal with simultaneous nitrification-denitrification in activated sludge systems. ASM2d is based on ASM2 and is expanded to include the denitrifying activity of the phosphorus accumulating organisms (PAOs......). This extension of ASM2 allows for improved modeling of the processes, especially with respect to the dynamics of nitrate and phosphate. (C) 1999 IAWQ Published by Elsevier Science Ltd. All rights reserved....
Large scale 2D spectral compressed sensing in continuous domain
Cai, Jian-Feng
2017-06-20
We consider the problem of spectral compressed sensing in continuous domain, which aims to recover a 2-dimensional spectrally sparse signal from partially observed time samples. The signal is assumed to be a superposition of s complex sinusoids. We propose a semidefinite program for the 2D signal recovery problem. Our model is able to handle large scale 2D signals of size 500 × 500, whereas traditional approaches only handle signals of size around 20 × 20.
Gaidyte, Rita
2010-01-01
Many inventors and companies still use 2D drawings and are starting to realize a 3D design because 3D modeling can save time and money. In this project I am going to compare 2D and 3D drawings and modeling. 2D modeling and 3D modeling have advantages and disadvantages. For this comparison I made 2D and 3D models using AutoCAD, Autodesk Revit Architectural and Revit MEP software. So, I am going to compare CAD (Computer-aided design) and BIM (Building Information Modeling) technologies, beca...
International Nuclear Information System (INIS)
Ginsparg, P.
1991-01-01
These are introductory lectures for a general audience that give an overview of the subject of matrix models and their application to random surfaces, 2d gravity, and string theory. They are intentionally 1.5 years out of date
International Nuclear Information System (INIS)
David, F.
1990-01-01
In these lectures, I shall focus on the matrix formulation of 2-d gravity. In the first one, I shall discuss the main results of the continuum formulation of 2-d gravity, starting from the first renormalization group calculations which led to the concept of the conformal anomaly, going through the Polyakov bosonic string and the Liouville action, up to the recent results on the scaling properties of conformal field theories coupled to 2-d gravity. In the second lecture, I shall discuss the discrete formulation of 2-d gravity in term of random lattices, and the mapping onto random matrix models. The occurrence of critical points in the planar limit and the scaling limit at those critical points will be described, as well as the identification of these scaling limits with continuum 2-d gravity coupled to some matter field theory. In the third lecture, the double scaling limit in the one matrix model, and its connection with continuum non perturbative 2-d gravity, will be presented. The connection with the KdV hierarchy and the general form of the string equation will be discuted. In the fourth lecture, I shall discuss the non-perturbative effects present in the non perturbative solutions, in the case of pure gravity. The Schwinger-Dyson equations for pure gravity in the double scaling limit are described and their compatibility with the solutions of the string equation for pure gravity is shown to be somewhat problematic
2-D Model Test of Dolosse Breakwater
DEFF Research Database (Denmark)
Burcharth, Hans F.; Liu, Zhou
1994-01-01
The rational design diagram for Dolos armour should incorporate both the hydraulic stability and the structural integrity. The previous tests performed by Aalborg University (AU) made available such design diagram for the trunk of Dolos breakwater without superstructures (Burcharth et al. 1992......). To extend the design diagram to cover Dolos breakwaters with superstructure, 2-D model tests of Dolos breakwater with wave wall is included in the project Rubble Mound Breakwater Failure Modes sponsored by the Directorate General XII of the Commission of the European Communities under Contract MAS-CT92......-0042. Furthermore, Task IA will give the design diagram for Tetrapod breakwaters without a superstructure. The more complete research results on Dolosse can certainly give some insight into the behaviour of Tetrapods armour layer of the breakwaters with superstructure. The main part of the experiment...
DEFF Research Database (Denmark)
Burcharth, Hans F.; Meinert, Palle; Andersen, Thomas Lykke
the crown wall have been measured. The model has been subjected to irregular waves corresponding to typical conditions offshore from the intended prototype location. Characteristic situations have been video recorded. The stability of the toe has been investigated. The wave-generated forces on the caisson...
Downscaling the 2D Bénard convection equations using continuous data assimilation
Altaf, Muhammad
2017-02-27
We consider a recently introduced continuous data assimilation (CDA) approach for downscaling a coarse resolution configuration of the 2D Bénard convection equations into a finer grid. In this CDA, a nudging term, estimated as the misfit between some interpolants of the assimilated coarse-grid measurements and the fine-grid model solution, is added to the model equations to constrain the model. The main contribution of this study is a performance analysis of CDA for downscaling measurements of temperature and velocity. These measurements are assimilated either separately or simultaneously, and the results are compared against those resulting from the standard point-to-point nudging approach (NA). Our numerical results suggest that the CDA solution outperforms that of NA, always converging to the true solution when the velocity is assimilated as has been theoretically proven. Assimilation of temperature measurements only may not always recover the true state as demonstrated in the case study. Various runs are conducted to evaluate the sensitivity of CDA to noise in the measurements, the size, and the time frequency of the measured grid, suggesting a more robust behavior of CDA compared to that of NA.
2D numerical modelling of meandering channel formation
Indian Academy of Sciences (India)
To simulate the bend development and lateral migration of alluvial channels, a 2D numerical model must account for bend flow effects and river bank erosion processes. Subsequent works on helical flow and forces on sed- iment grains on a transversely sloping bed (e.g.,. Einstein and Shen 1964; Engelund 1974; Bathurst.
Consistency between 2D-3D Sediment Transport models
Villaret, Catherine; Jodeau, Magali
2017-04-01
Sediment transport models have been developed and applied by the engineering community to estimate transport rates and morphodynamic bed evolutions in river flows, coastal and estuarine conditions. Environmental modelling systems like the open-source Telemac modelling system include a hierarchy of models from 1D (Mascaret), 2D (Telemac-2D/Sisyphe) and 3D (Telemac-3D/Sedi-3D) and include a wide range of processes to represent sediment flow interactions under more and more complex situations (cohesive, non-cohesive and mixed sediment). Despite some tremendous progresses in the numerical techniques and computing resources, the quality/accuracy of model results mainly depend on the numerous choices and skills of the modeler. In complex situations involving stratification effects, complex geometry, recirculating flows… 2D model assumptions are no longer valid. A full 3D turbulent flow model is then required in order to capture the vertical mixing processes and to represent accurately the coupled flow/sediment distribution. However a number of theoretical and numerical difficulties arise when dealing with sediment transport modelling in 3D which will be high-lighted : (1) Dependency of model results to the vertical grid refinement and choice of boundary conditions and numerical scheme (2) The choice of turbulence model determines also the sediment vertical distribution which is governed by a balance between the downward settling term and upward turbulent diffusion. (3) The use of different numerical schemes for both hydrodynamics (mean and turbulent flow) and sediment transport modelling can lead to some inconsistency including a mismatch in the definition of numerical cells and definition of boundary conditions. We discuss here those present issues and present some detailed comparison between 2D and 3D simulations on a set of validation test cases which are available in the Telemac 7.2 release using both cohesive and non-cohesive sediments.
Preliminary 2D numerical modeling of common granular problems
Wyser, Emmanuel; Jaboyedoff, Michel
2017-04-01
Granular studies received an increasing interest during the last decade. Many scientific investigations were successfully addressed to acknowledge the ubiquitous behavior of granular matter. We investigate liquid impacts onto granular beds, i.e. the influence of the packing and compaction-dilation transition. However, a physically-based model is still lacking to address complex microscopic features of granular bed response during liquid impacts such as compaction-dilation transition or granular bed uplifts (Wyser et al. in review). We present our preliminary 2D numerical modeling based on the Discrete Element Method (DEM) using nonlinear contact force law (the Hertz-Mindlin model) for disk shape particles. The algorithm is written in C programming language. Our 2D model provides an analytical tool to address granular problems such as i) granular collapses and ii) static granular assembliy problems. This provides a validation framework of our numerical approach by comparing our numerical results with previous laboratory experiments or numerical works. Inspired by the work of Warnett et al. (2014) and Staron & Hinch (2005), we studied i) the axisymetric collapse of granular columns. We addressed the scaling between the initial aspect ratio and the final runout distance. Our numerical results are in good aggreement with the previous studies of Warnett et al. (2014) and Staron & Hinch (2005). ii) Reproducing static problems for regular and randomly stacked particles provides a valid comparison to results of Egholm (2007). Vertical and horizontal stresses within the assembly are quite identical to stresses obtained by Egholm (2007), thus demonstating the consistency of our 2D numerical model. Our 2D numerical model is able to reproduce common granular case studies such as granular collapses or static problems. However, a sufficient small timestep should be used to ensure a good numerical consistency, resulting in higher computational time. The latter becomes critical
Maximizing entropy of image models for 2-D constrained coding
DEFF Research Database (Denmark)
Forchhammer, Søren; Danieli, Matteo; Burini, Nino
2010-01-01
This paper considers estimating and maximizing the entropy of two-dimensional (2-D) fields with application to 2-D constrained coding. We consider Markov random fields (MRF), which have a non-causal description, and the special case of Pickard random fields (PRF). The PRF are 2-D causal finite...... context models, which define stationary probability distributions on finite rectangles and thus allow for calculation of the entropy. We consider two binary constraints and revisit the hard square constraint given by forbidding neighboring 1s and provide novel results for the constraint that no uniform 2...... £ 2 squares contains all 0s or all 1s. The maximum values of the entropy for the constraints are estimated and binary PRF satisfying the constraint are characterized and optimized w.r.t. the entropy. The maximum binary PRF entropy is 0.839 bits/symbol for the no uniform squares constraint. The entropy...
Gold-standard performance for 2D hydrodynamic modeling
Pasternack, G. B.; MacVicar, B. J.
2013-12-01
Two-dimensional, depth-averaged hydrodynamic (2D) models are emerging as an increasingly useful tool for environmental water resources engineering. One of the remaining technical hurdles to the wider adoption and acceptance of 2D modeling is the lack of standards for 2D model performance evaluation when the riverbed undulates, causing lateral flow divergence and convergence. The goal of this study was to establish a gold-standard that quantifies the upper limit of model performance for 2D models of undulating riverbeds when topography is perfectly known and surface roughness is well constrained. A review was conducted of published model performance metrics and the value ranges exhibited by models thus far for each one. Typically predicted velocity differs from observed by 20 to 30 % and the coefficient of determination between the two ranges from 0.5 to 0.8, though there tends to be a bias toward overpredicting low velocity and underpredicting high velocity. To establish a gold standard as to the best performance possible for a 2D model of an undulating bed, two straight, rectangular-walled flume experiments were done with no bed slope and only different bed undulations and water surface slopes. One flume tested model performance in the presence of a porous, homogenous gravel bed with a long flat section, then a linear slope down to a flat pool bottom, and then the same linear slope back up to the flat bed. The other flume had a PVC plastic solid bed with a long flat section followed by a sequence of five identical riffle-pool pairs in close proximity, so it tested model performance given frequent undulations. Detailed water surface elevation and velocity measurements were made for both flumes. Comparing predicted versus observed velocity magnitude for 3 discharges with the gravel-bed flume and 1 discharge for the PVC-bed flume, the coefficient of determination ranged from 0.952 to 0.987 and the slope for the regression line was 0.957 to 1.02. Unsigned velocity
Timoshevskiy, M. V.; Zapryagaev, I. I.; Pervunin, K. S.; Markovich, D. M.
2016-10-01
In the paper, the possibility of active control of a cavitating flow over a 2D hydrofoil that replicates a scaled-down model of high-pressure hydroturbine guide vane (GV) was tested. The flow manipulation was implemented by a continuous tangential liquid injection at different flow rates through a spanwise slot in the foil surface. In experiments, the hydrofoil was placed in the test channel at the attack angle of 9°. Different cavitation conditions were reached by varying the cavitation number and injection velocity. In order to study time dynamics and spatial patterns of partial cavities, high-speed imaging was employed. A PIV method was used to measure the mean and fluctuating velocity fields over the hydrofoil. Hydroacoustic measurements were carried out by means of a pressure transducer to identify spectral characteristics of the cavitating flow. It was found that the present control technique is able to modify the partial cavity pattern (or even totally suppress cavitation) in case of stable sheet cavitation and change the amplitude of pressure pulsations at unsteady regimes. The injection technique makes it also possible to significantly influence the spatial distributions of the mean velocity and its turbulent fluctuations over the GV section for non-cavitating flow and sheet cavitation.
2D CFD Analysis of an Airfoil with Active Continuous Trailing Edge Flap
Jaksich, Dylan; Shen, Jinwei
2014-11-01
Efficient and quieter helicopter rotors can be achieved through on-blade control devices, such as active Continuous Trailing-Edge Flaps driven by embedded piezoelectric material. This project aims to develop a CFD simulation tool to predict the aerodynamic characteristics of an airfoil with CTEF using open source code: OpenFOAM. Airfoil meshes used by OpenFOAM are obtained with MATLAB scripts. Once created it is possible to rotate the airfoil to various angles of attack. When the airfoil is properly set up various OpenFOAM properties, such as kinematic viscosity and flow velocity, are altered to achieve the desired testing conditions. Upon completion of a simulation, the program gives the lift, drag, and moment coefficients as well as the pressure and velocity around the airfoil. The simulation is then repeated across multiple angles of attack to give full lift and drag curves. The results are then compared to previous test data and other CFD predictions. This research will lead to further work involving quasi-steady 2D simulations incorporating NASTRAN to model aeroelastic deformation and eventually to 3D aeroelastic simulations. NSF ECE Grant #1358991 supported the first author as an REU student.
Simplistic approach for 2D grown-in microdefect modeling
Energy Technology Data Exchange (ETDEWEB)
Prostomolotov, Anatoly; Verezub, Nataliya [Institute for Problems in Mechanics, Russian Academy of Sciences, Moscow (Russian Federation)
2009-08-15
In the present paper the analysis of cooling conditions influence on microdefect formation in Si single crystal was carried out on the basis of an analytical formulation for crystal temperature field jointly with developed two-dimensional (2D) models of microdefect formation. The new mathematical model is applied for calculations of vacancy microdefect formation, in which the 2D vacancy migration process is taken into account and the approached calculation algorithm is offered, which is not requiring the data storage for whole defect growth pre-history. The calculated results are discussed for conditions of Cz silicon single crystal growing. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Numerical 2D-modeling of multiroll leveling
Mathieu, N.; Potier-Ferry, M.; Zahrouni, H.
2016-10-01
Multiroll leveling is a forming process used in the metals industries (aluminum, steel, …) in order to correct flatness defects and minimize residual stresses in strips thanks to alternating bending. This work proposes a Finite Element 2D model to simulate the metal sheet conveying through the machine. Obtained results (plastic strain and residual stress distributions through thickness) are analysed. Strip deformation, after elastic springback and potential buckling, is also predicted (residual curvatures).
Influence of Elevation Data Source on 2D Hydraulic Modelling
Bakuła, Krzysztof; StĘpnik, Mateusz; Kurczyński, Zdzisław
2016-08-01
The aim of this paper is to analyse the influence of the source of various elevation data on hydraulic modelling in open channels. In the research, digital terrain models from different datasets were evaluated and used in two-dimensional hydraulic models. The following aerial and satellite elevation data were used to create the representation of terrain-digital terrain model: airborne laser scanning, image matching, elevation data collected in the LPIS, EuroDEM, and ASTER GDEM. From the results of five 2D hydrodynamic models with different input elevation data, the maximum depth and flow velocity of water were derived and compared with the results of the most accurate ALS data. For such an analysis a statistical evaluation and differences between hydraulic modelling results were prepared. The presented research proved the importance of the quality of elevation data in hydraulic modelling and showed that only ALS and photogrammetric data can be the most reliable elevation data source in accurate 2D hydraulic modelling.
2D numerical modelling of meandering channel formation
XIAO, Y.; ZHOU, G.; YANG, F. S.
2016-03-01
A 2D depth-averaged model for hydrodynamic sediment transport and river morphological adjustment was established. The sediment transport submodel takes into account the influence of non-uniform sediment with bed surface armoring and considers the impact of secondary flow in the direction of bed-load transport and transverse slope of the river bed. The bank erosion submodel incorporates a simple simulation method for updating bank geometry during either degradational or aggradational bed evolution. Comparison of the results obtained by the extended model with experimental and field data, and numerical predictions validate that the proposed model can simulate grain sorting in river bends and duplicate the characteristics of meandering river and its development. The results illustrate that by using its control factors, the improved numerical model can be applied to simulate channel evolution under different scenarios and improve understanding of patterning processes.
Brane brick models and 2d(0,2) triality
Energy Technology Data Exchange (ETDEWEB)
Franco, Sebastián [Physics Department, The City College of the CUNY,160 Convent Avenue, New York, NY 10031 (United States); The Graduate School and University Center, The City University of New York,365 Fifth Avenue, New York NY 10016 (United States); Lee, Sangmin [Center for Theoretical Physics, Seoul National University,Seoul 08826 (Korea, Republic of); Department of Physics and Astronomy, Seoul National University,Seoul 08826 (Korea, Republic of); College of Liberal Studies, Seoul National University,Seoul 08826 (Korea, Republic of); School of Natural Sciences, Institute for Advanced Study,Princeton, NJ 08540 (United States); Seong, Rak-Kyeong [School of Physics, Korea Institute for Advanced Study,Seoul 02455 (Korea, Republic of)
2016-05-04
We provide a brane realization of 2d(0,2) Gadde-Gukov-Putrov triality in terms of brane brick models. These are Type IIA brane configurations that are T-dual to D1-branes over singular toric Calabi-Yau 4-folds. Triality translates into a local transformation of brane brick models, whose simplest representative is a cube move. We present explicit examples and construct their triality networks. We also argue that the classical mesonic moduli space of brane brick model theories, which corresponds to the probed Calabi-Yau 4-fold, is invariant under triality. Finally, we discuss triality in terms of phase boundaries, which play a central role in connecting Calabi-Yau 4-folds to brane brick models.
Validation of 2D flood models with insurance claims
Zischg, Andreas Paul; Mosimann, Markus; Bernet, Daniel Benjamin; Röthlisberger, Veronika
2018-02-01
Flood impact modelling requires reliable models for the simulation of flood processes. In recent years, flood inundation models have been remarkably improved and widely used for flood hazard simulation, flood exposure and loss analyses. In this study, we validate a 2D inundation model for the purpose of flood exposure analysis at the river reach scale. We validate the BASEMENT simulation model with insurance claims using conventional validation metrics. The flood model is established on the basis of available topographic data in a high spatial resolution for four test cases. The validation metrics were calculated with two different datasets; a dataset of event documentations reporting flooded areas and a dataset of insurance claims. The model fit relating to insurance claims is in three out of four test cases slightly lower than the model fit computed on the basis of the observed inundation areas. This comparison between two independent validation data sets suggests that validation metrics using insurance claims can be compared to conventional validation data, such as the flooded area. However, a validation on the basis of insurance claims might be more conservative in cases where model errors are more pronounced in areas with a high density of values at risk.
A 2D simulation model for urban flood management
Price, Roland; van der Wielen, Jonathan; Velickov, Slavco; Galvao, Diogo
2014-05-01
The European Floods Directive, which came into force on 26 November 2007, requires member states to assess all their water courses and coast lines for risk of flooding, to map flood extents and assets and humans at risk, and to take adequate and coordinated measures to reduce the flood risk in consultation with the public. Flood Risk Management Plans are to be in place by 2015. There are a number of reasons for the promotion of this Directive, not least because there has been much urban and other infrastructural development in flood plains, which puts many at risk of flooding along with vital societal assets. In addition there is growing awareness that the changing climate appears to be inducing more frequent extremes of rainfall with a consequent increases in the frequency of flooding. Thirdly, the growing urban populations in Europe, and especially in the developing countries, means that more people are being put at risk from a greater frequency of urban flooding in particular. There are urgent needs therefore to assess flood risk accurately and consistently, to reduce this risk where it is important to do so or where the benefit is greater than the damage cost, to improve flood forecasting and warning, to provide where necessary (and possible) flood insurance cover, and to involve all stakeholders in decision making affecting flood protection and flood risk management plans. Key data for assessing risk are water levels achieved or forecasted during a flood. Such levels should of course be monitored, but they also need to be predicted, whether for design or simulation. A 2D simulation model (PriceXD) solving the shallow water wave equations is presented specifically for determining flood risk, assessing flood defense schemes and generating flood forecasts and warnings. The simulation model is required to have a number of important properties: -Solve the full shallow water wave equations using a range of possible solutions; -Automatically adjust the time step and
GENERALIZATION TECHNIQUE FOR 2D+SCALE DHE DATA MODEL
Directory of Open Access Journals (Sweden)
H. Karim
2016-10-01
Full Text Available Different users or applications need different scale model especially in computer application such as game visualization and GIS modelling. Some issues has been raised on fulfilling GIS requirement of retaining the details while minimizing the redundancy of the scale datasets. Previous researchers suggested and attempted to add another dimension such as scale or/and time into a 3D model, but the implementation of scale dimension faces some problems due to the limitations and availability of data structures and data models. Nowadays, various data structures and data models have been proposed to support variety of applications and dimensionality but lack research works has been conducted in terms of supporting scale dimension. Generally, the Dual Half Edge (DHE data structure was designed to work with any perfect 3D spatial object such as buildings. In this paper, we attempt to expand the capability of the DHE data structure toward integration with scale dimension. The description of the concept and implementation of generating 3D-scale (2D spatial + scale dimension for the DHE data structure forms the major discussion of this paper. We strongly believed some advantages such as local modification and topological element (navigation, query and semantic information in scale dimension could be used for the future 3D-scale applications.
A 2D Model of Hydraulic Fracturing, Damage and Microseismicity
Wangen, Magnus
2018-03-01
We present a model for hydraulic fracturing and damage of low-permeable rock. It computes the intermittent propagation of rock damage, microseismic event locations, microseismic frequency-magnitude distributions, stimulated rock volume and the injection pressure. The model uses a regular 2D grid and is based on ideas from invasion percolation. All damaged and connected cells during a time step constitute a microseismic event, where the size of the event is the number of cells in the cluster. The magnitude of the event is the log _{10} of the event size. The model produces events with a magnitude-frequency distribution having a b value that is approximately 0.8. The model is studied with respect to the physical parameters: permeability of damaged rock and the rock strength. "High" permeabilities of the damaged rock give the same b value ≈ 0.8, but "moderate" permeabilities give higher b values. Another difference is that "high" permeabilities produce a percolation-like fracture network, while "moderate" permeabilities result in damage zones that expand circularly away from the injection point. In the latter case of "moderate" permeabilities, the injection pressure increases substantially beyond the fracturing level. The rock strength and the time step do not change the observed b value of the model for moderate changes.
2D modelling and its applications in engineering
International Nuclear Information System (INIS)
Altinbalik, M. Tahir; İRSEL, Gürkan
2013-01-01
A model, in computer aided engineering applications, may be created by either using a two- dimensional or a three-dimensional design depending on the purpose of design. What matters most in this regard is the selection of a right method to meet system solution requirements in the most economical way. Manufacturability of a design that is developed by utilising computer aided engineering is important, but usability of the data obtained in the course of design works in the production is also equally important. In the applications consisting of such production operations as CNC or plasma cutting, two-dimensional designs can be directly used in production. These machines are equipped with interfaces which converts two-dimensional drawings into codes. In this way, a design can be directly transferred to production, and any arrangements during production process can be synchronously evaluated. As a result of this, investment expenses will be lowered, and thus the costs can be reduced to some extent. In the presented study, we have studied two-dimensional design applications and requirements. We created a two-dimensional design for a part for which a three-dimensional model have previously been generated, and then, we transferred this design to plasma cutting machine, and thus, the operation has been realized experimentally. Key words: Plasma Cutting, 2D modelling, flexibility
Ab initio modeling of 2D layered organohalide lead perovskites
Energy Technology Data Exchange (ETDEWEB)
Fraccarollo, Alberto; Cantatore, Valentina; Boschetto, Gabriele; Marchese, Leonardo; Cossi, Maurizio, E-mail: maurizio.cossi@uniupo.it [Dipartimento di Scienze e Innovazione Tecnologica (DISIT), Università del Piemonte Orientale, via T. Michel 11, I-15121 Alessandria (Italy)
2016-04-28
A number of 2D layered perovskites A{sub 2}PbI{sub 4} and BPbI{sub 4}, with A and B mono- and divalent ammonium and imidazolium cations, have been modeled with different theoretical methods. The periodic structures have been optimized (both in monoclinic and in triclinic systems, corresponding to eclipsed and staggered arrangements of the inorganic layers) at the DFT level, with hybrid functionals, Gaussian-type orbitals and dispersion energy corrections. With the same methods, the various contributions to the solid stabilization energy have been discussed, separating electrostatic and dispersion energies, organic-organic intralayer interactions and H-bonding effects, when applicable. Then the electronic band gaps have been computed with plane waves, at the DFT level with scalar and full relativistic potentials, and including the correlation energy through the GW approximation. Spin orbit coupling and GW effects have been combined in an additive scheme, validated by comparing the computed gap with well known experimental and theoretical results for a model system. Finally, various contributions to the computed band gaps have been discussed on some of the studied systems, by varying some geometrical parameters and by substituting one cation in another’s place.
QSAR Models for P-450 (2D6) Substrate Activity
DEFF Research Database (Denmark)
Ringsted, Tine; Nikolov, Nikolai Georgiev; Jensen, Gunde Egeskov
2009-01-01
Human Cytochrome P450 (CYP) is a large group of enzymes that possess an essential function in metabolising different exogenous and endogenous compounds. Humans have more than 50 different genes encoding CYP enzymes, among these a gene encoding for the CYP isoenzyme 2D6, a CYP able to metabolise d...... substrates. These chemicals are potentially present in the environment. The biological importance of the CYP 2D6 and the use of the software mentioned above were discussed....
More on supersymmetric and 2d analogs of the SYK model
Murugan, Jeff; Stanford, Douglas; Witten, Edward
2017-08-01
In this paper, we explore supersymmetric and 2d analogs of the SYK model. We begin by working out a basis of (super)conformal eigenfunctions appropriate for expanding a four-point function. We use this to clarify some details of the 1d supersymmetric SYK model. We then introduce new bosonic and supersymmetric analogs of SYK in two dimensions. These theories consist of N fields interacting with random q-field interactions. Although models built entirely from bosons appear to be problematic, we find a supersymmetric model that flows to a large N CFT with interaction strength of order one. We derive an integral formula for the four-point function at order 1 /N , and use it to compute the central charge, chaos exponent and some anomalous dimensions. We describe a problem that arises if one tries to find a 2d SYK-like CFT with a continuous global symmetry.
Numerical modelling of unsteady 2D sheet cavitation
de Lange, D.F.; de Bruin, G.J.; van Wijngaarden, L.; van Wijngaarden, L.
1996-01-01
Unsteady 2D sheet cavitation has been calculated by a BEM. Cubics are used to represent various quantities like the potential on the wet part of the profile, the normal velocity on the sheet, the geometry of the profile and the sheet. The growing cavity sheet, the re-entrant jet and the sheet
Evaluation of Fish Passage at Whitewater Parks Using 2D and 3D Hydraulic Modeling
Hardee, T.; Nelson, P. A.; Kondratieff, M.; Bledsoe, B. P.
2016-12-01
In-stream whitewater parks (WWPs) are increasingly popular recreational amenities that typically create waves by constricting flow through a chute to increase velocities and form a hydraulic jump. However, the hydraulic conditions these structures create can limit longitudinal habitat connectivity and potentially inhibit upstream fish migration, especially of native fishes. An improved understanding of the fundamental hydraulic processes and potential environmental effects of whitewater parks is needed to inform management decisions about Recreational In-Channel Diversions (RICDs). Here, we use hydraulic models to compute a continuous and spatially explicit description of velocity and depth along potential fish swimming paths in the flow field, and the ensemble of potential paths are compared to fish swimming performance data to predict fish passage via logistic regression analysis. While 3d models have been shown to accurately predict trout movement through WWP structures, 2d methods can provide a more cost-effective and manager-friendly approach to assessing the effects of similar hydraulic structures on fish passage when 3d analysis in not feasible. Here, we use 2d models to examine the hydraulics in several WWP structures on the North Fork of the St. Vrain River at Lyons, Colorado, and we compare these model results to fish passage predictions from a 3d model. Our analysis establishes a foundation for a practical, transferable and physically-rigorous 2d modeling approach for mechanistically evaluating the effects of hydraulic structures on fish passage.
Seepage and Piping through Levees and Dikes using 2D and 3D Modeling Codes
2016-06-01
Flood & Coastal Storm Damage Reduction Program ERDC/CHL TR-16-6 June 2016 Seepage and Piping through Levees and Dikes Using 2D and 3D Modeling Codes...of this Technical Report is to evaluate the benefits of three- dimensional ( 3D ) modeling of common seepage and piping issues along embankments over...traditional two-dimensional (2D) models . To facilitate the evaluation, one 3D model , two 2D cross-sectional models , and one 2D plan-view model were
Implementation of true continuous bed motion in 2-D and 3-D whole-body PET scanning
Dahlbom, M.; Reed, J.; Young, J.
2001-08-01
True continuous axial bed motion has been implemented on a high-resolution positron emission tomography (PET) scanner for use in both two-dimensional (2-D) and three-dimensional (3-D) acquisition modes. This has been accomplished by modifications in the bed motion controller firmware and by acquiring data in list mode. The new bed controller firmware was shown to provide an accurate and constant bed speed down to 0.25 mm/s with a moderate patient weight load. The constant bed motion eliminates previously reported dead-time due to bed positioning when using small discrete bed steps. The continuous bed motion was tested on uniform phantoms, in 2-D and 3-D. As a result of the continuous axial motion, a uniform axial sensitivity is achieved. This was also reflected in the reconstructed images, which showed an improvement in axial image uniformity (1.4% for continuous sampling, 5.0% for discrete) as well as an improvement in %SD uniformity in comparison to conventional step-and-shoot acquisitions. The use of the continuous axial motion also provide slight improvements in 2-D emission and transmission scanning, resulting in an overall improved image quality in whole-body PET.
Modelling heterogeneity of concrete using 2D lattice network for ...
Indian Academy of Sciences (India)
In this paper, numerical modelling of fracture in concrete using two-dimensional lattice model is presented and also a few issues related to lattice modelling technique applicable to concrete fracture are reviewed. A comparison is made with acoustic emission (AE) events with the number of fractured elements. To implement ...
2d Model Field Theories at Finite Temperature and Density
Schoen, Verena; Thies, Michael
2000-01-01
In certain 1+1 dimensional field theoretic toy models, one can go all the way from microscopic quarks via the hadron spectrum to the properties of hot and dense baryonic matter in an essentially analytic way. This "miracle" is illustrated through case studies of two popular large N models, the Gross-Neveu and the 't Hooft model - caricatures of the Nambu-Jona-Lasinio model and real QCD, respectively. The main emphasis will be on aspects related to spontaneous symmetry breaking (discrete or co...
2-D Model Test Study of the Suape Breakwater, Brazil
DEFF Research Database (Denmark)
Andersen, Thomas Lykke; Burcharth, Hans F.; Sopavicius, A.
This report deals with a two-dimensional model test study of the extension of the breakwater in Suape, Brazil. One cross-section was tested for stability and overtopping in various sea conditions. The length scale used for the model tests was 1:35. Unless otherwise specified all values given...
2D sigma models and differential Poisson algebras
Energy Technology Data Exchange (ETDEWEB)
Arias, Cesar [Departamento de Ciencias Físicas, Universidad Andres Bello,Republica 220, Santiago (Chile); Boulanger, Nicolas [Service de Mécanique et Gravitation, Université de Mons - UMONS,20 Place du Parc, 7000 Mons (Belgium); Laboratoire de Mathématiques et Physique Théorique,Unité Mixte de Recherche 7350 du CNRS, Fédération de Recherche 2964 Denis Poisson,Université François Rabelais, Parc de Grandmont, 37200 Tours (France); Sundell, Per [Departamento de Ciencias Físicas, Universidad Andres Bello,Republica 220, Santiago (Chile); Torres-Gomez, Alexander [Departamento de Ciencias Físicas, Universidad Andres Bello,Republica 220, Santiago (Chile); Instituto de Ciencias Físicas y Matemáticas, Universidad Austral de Chile-UACh,Valdivia (Chile)
2015-08-18
We construct a two-dimensional topological sigma model whose target space is endowed with a Poisson algebra for differential forms. The model consists of an equal number of bosonic and fermionic fields of worldsheet form degrees zero and one. The action is built using exterior products and derivatives, without any reference to a worldsheet metric, and is of the covariant Hamiltonian form. The equations of motion define a universally Cartan integrable system. In addition to gauge symmetries, the model has one rigid nilpotent supersymmetry corresponding to the target space de Rham operator. The rigid and local symmetries of the action, respectively, are equivalent to the Poisson bracket being compatible with the de Rham operator and obeying graded Jacobi identities. We propose that perturbative quantization of the model yields a covariantized differential star product algebra of Kontsevich type. We comment on the resemblance to the topological A model.
Quasicomplex N=2, d=1 Supersymmetric Sigma Models
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Evgeny A. Ivanov
2013-11-01
Full Text Available We derive and discuss a new type of N=2 supersymmetric quantum mechanical sigma models which appear when the superfield action of the (1,2,1 multiplets is modified by adding an imaginary antisymmetric tensor to the target space metric, thus completing the latter to a non-symmetric Hermitian metric. These models are not equivalent to the standard de Rham sigma models, but are related to them through a certain special similarity transformation of the supercharges. On the other hand, they can be obtained by a Hamiltonian reduction from the complex supersymmetric N=2 sigma models built on the multiplets (2,2,0 and describing the Dolbeault complex on the manifolds with proper isometries. We study in detail the extremal two-dimensional case, when the target space metric is defined solely by the antisymmetric tensor, and show that the corresponding quantum systems reveal a hidden N=4 supersymmetry.
A 2-D model for friction of complex anisotropic surfaces
Costagliola, Gianluca; Bosia, Federico; Pugno, Nicola M.
2018-03-01
The friction force observed at macroscale is the result of interactions at various lower length scales that are difficult to model in a combined manner. For this reason, simplified approaches are required, depending on the specific aspect to be investigated. In particular, the dimensionality of the system is often reduced, especially in models designed to provide a qualitative description of frictional properties of elastic materials, e.g. the spring-block model. In this paper, we implement for the first time a two dimensional extension of the spring-block model, applying it to structured surfaces and investigating by means of numerical simulations the frictional behaviour of a surface in the presence of features like cavities, pillars or complex anisotropic structures. We show how friction can be effectively tuned by appropriate design of such surface features.
Improvement of a 2D numerical model of lava flows
Ishimine, Y.
2013-12-01
I propose an improved procedure that reduces an improper dependence of lava flow directions on the orientation of Digital Elevation Model (DEM) in two-dimensional simulations based on Ishihara et al. (in Lava Flows and Domes, Fink, JH eds., 1990). The numerical model for lava flow simulations proposed by Ishihara et al. (1990) is based on two-dimensional shallow water model combined with a constitutive equation for a Bingham fluid. It is simple but useful because it properly reproduces distributions of actual lava flows. Thus, it has been regarded as one of pioneer work of numerical simulations of lava flows and it is still now widely used in practical hazard prediction map for civil defense officials in Japan. However, the model include an improper dependence of lava flow directions on the orientation of DEM because the model separately assigns the condition for the lava flow to stop due to yield stress for each of two orthogonal axes of rectangular calculating grid based on DEM. This procedure brings a diamond-shaped distribution as shown in Fig. 1 when calculating a lava flow supplied from a point source on a virtual flat plane although the distribution should be circle-shaped. To improve the drawback, I proposed a modified procedure that uses the absolute value of yield stress derived from both components of two orthogonal directions of the slope steepness to assign the condition for lava flows to stop. This brings a better result as shown in Fig. 2. Fig. 1. (a) Contour plots calculated with the original model of Ishihara et al. (1990). (b) Contour plots calculated with a proposed model.
Directory of Open Access Journals (Sweden)
Timoshevskiy Mikhail V.
2016-01-01
Full Text Available We studied cavitating flow over the suction side of a symmetric 2D foil – a scaled-down model of high-pressure hydroturbine guide vanes (GV – in different cavitation regimes at the attack angle of 3°. High-speed imaging was used to analyze spatial patterns and time dynamics of the gas-vapour cavities. A hydroacoustic pressure transducer was employed to register time-spectra of pressure fluctuations nearby the hydrofoil. A PIV technique was applied to measure the velocity fields and its fluctuations. The active flow control was implemented by means of a continuous liquid supply with different flow rates through a slot channel located in the GV surface. It was found that the active mass injection does not influence the primary flow upstream of the slot channel position. For the cavitation-free and cavitation inception cases, the injection was shown to make the turbulent wake past the GV section more intense. However, at the developed cavitation regimes the active flow management made it possible to reduce substantially the amplitude or even totally suppress the periodic cavity length oscillations and pressure pulsations associated with them.
Modelling heterogeneity of concrete using 2D lattice network for ...
Indian Academy of Sciences (India)
present work brings out certain finer details which are not available explicitly in the earlier works. Keywords. Concrete fracture; lattice model; Fuller distribution; ... examples are cement mortar and concrete in civil engineering. ..... Although acoustic emission technique is a well established non destructive testing (NDT).
2D Modeling and Classification of Extended Objects in a Network of HRR Radars
Fasoula, A.
2011-01-01
In this thesis, the modeling of extended objects with low-dimensional representations of their 2D geometry is addressed. The ultimate objective is the classification of the objects using libraries of such compact 2D object models that are much smaller than in the state-of-the-art classification
Coupled 1D-2D hydrodynamic inundation model for sewer overflow: Influence of modeling parameters
Directory of Open Access Journals (Sweden)
Adeniyi Ganiyu Adeogun
2015-10-01
Full Text Available This paper presents outcome of our investigation on the influence of modeling parameters on 1D-2D hydrodynamic inundation model for sewer overflow, developed through coupling of an existing 1D sewer network model (SWMM and 2D inundation model (BREZO. The 1D-2D hydrodynamic model was developed for the purpose of examining flood incidence due to surcharged water on overland surface. The investigation was carried out by performing sensitivity analysis on the developed model. For the sensitivity analysis, modeling parameters, such as mesh resolution Digital Elevation Model (DEM resolution and roughness were considered. The outcome of the study shows the model is sensitive to changes in these parameters. The performance of the model is significantly influenced, by the Manning's friction value, the DEM resolution and the area of the triangular mesh. Also, changes in the aforementioned modeling parameters influence the Flood characteristics, such as the inundation extent, the flow depth and the velocity across the model domain.
A 2D Electromechanical Model of Human Atrial Tissue Using the Discrete Element Method
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Paul Brocklehurst
2015-01-01
Full Text Available Cardiac tissue is a syncytium of coupled cells with pronounced intrinsic discrete nature. Previous models of cardiac electromechanics often ignore such discrete properties and treat cardiac tissue as a continuous medium, which has fundamental limitations. In the present study, we introduce a 2D electromechanical model for human atrial tissue based on the discrete element method (DEM. In the model, single-cell dynamics are governed by strongly coupling the electrophysiological model of Courtemanche et al. to the myofilament model of Rice et al. with two-way feedbacks. Each cell is treated as a viscoelastic body, which is physically represented by a clump of nine particles. Cell aggregations are arranged so that the anisotropic nature of cardiac tissue due to fibre orientations can be modelled. Each cell is electrically coupled to neighbouring cells, allowing excitation waves to propagate through the tissue. Cell-to-cell mechanical interactions are modelled using a linear contact bond model in DEM. By coupling cardiac electrophysiology with mechanics via the intracellular Ca2+ concentration, the DEM model successfully simulates the conduction of cardiac electrical waves and the tissue’s corresponding mechanical contractions. The developed DEM model is numerically stable and provides a powerful method for studying the electromechanical coupling problem in the heart.
Modeling Overlapping Laminations in Magnetic Core Materials Using 2-D Finite-Element Analysis
DEFF Research Database (Denmark)
Jensen, Bogi Bech; Guest, Emerson David; Mecrow, Barrie C.
2015-01-01
This paper describes a technique for modeling overlapping laminations in magnetic core materials using two-dimensional finite-element (2-D FE) analysis. The magnetizing characteristic of the overlapping region is captured using a simple 2-D FE model of the periodic overlapping geometry...... and a composite material is created, which has the same magnetization characteristic. The benefit of this technique is that it allows a designer to perform design and optimization of magnetic cores with overlapped laminations using a 2-D FE model rather than a 3-D FE model, which saves modeling and simulation...... time. The modeling technique is verified experimentally by creating a composite material of a lap joint with a 3-mm overlapping region and using it in a 2-D FE model of a ring sample made up of a stack of 20 laminations. The B-H curve of the simulated ring sample is compared with the B-H curve obtained...
The strong-weak coupling symmetry in 2D Φ4 field models
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B.N.Shalaev
2005-01-01
Full Text Available It is found that the exact beta-function β(g of the continuous 2D gΦ4 model possesses two types of dual symmetries, these being the Kramers-Wannier (KW duality symmetry and the strong-weak (SW coupling symmetry f(g, or S-duality. All these transformations are explicitly constructed. The S-duality transformation f(g is shown to connect domains of weak and strong couplings, i.e. above and below g*. Basically it means that there is a tempting possibility to compute multiloop Feynman diagrams for the β-function using high-temperature lattice expansions. The regular scheme developed is found to be strongly unstable. Approximate values of the renormalized coupling constant g* found from duality symmetry equations are in an agreement with available numerical results.
Ghostine, Rabih
2014-12-01
In open channel networks, flow is usually approximated by the one-dimensional (1D) Saint-Venant equations coupled with an empirical junction model. In this work, a comparison in terms of accuracy and computational cost between a coupled 1D-2D shallow water model and a fully two-dimensional (2D) model is presented. The paper explores the ability of a coupled model to simulate the flow processes during supercritical flows in crossroads. This combination leads to a significant reduction in the computational time, as a 1D approach is used in branches and a 2D approach is employed in selected areas only where detailed flow information is essential. Overall, the numerical results suggest that the coupled model is able to accurately simulate the main flow processes. In particular, hydraulic jumps, recirculation zones, and discharge distribution are reasonably well reproduced and clearly identified. Overall, the proposed model leads to a 30% reduction in run times. © 2014 International Association for Hydro-Environment Engineering and Research.
2-D model for pollutant dispersion at the coastal outfall off Paradip
Digital Repository Service at National Institute of Oceanography (India)
Suryanarayana, A.; Babu, M.T.; Vethamony, P.; Gouveia, A.D.
Simulation of dispersion of the effluent discharge has been carried out using 2-D Model to verify the advection and diffusion of the pollutant patch of the proposed effluent disposal off Paradip, Orissa, India. The simulation of dispersion...
Activated sludge models ASM1, ASM2, ASM2d and ASM3
DEFF Research Database (Denmark)
Henze, Mogens; Gujer, W.; Mino, T.
This book has been produced to give a total overview of the Activated Sludge Model (ASM) family at the start of 2000 and to give the reader easy access to the different models in their original versions. It thus presents ASM1, ASM2, ASM2d and ASM3 together for the first time.Modelling of activated...... sludge processes has become a common part of the design and operation of wastewater treatment plants. Today models are being used in design, control, teaching and research.ContentsASM3: Introduction, Comparison of ASM1 and ASM3, ASM3: Definition of compounds in the model, ASM3: Definition of processes...... in the Model, ASM3: Stoichiometry, ASM3: Kinetics, Limitations of ASM3, Aspects of application of ASM3, ASM3C: A Carbon based model, Conclusion ASM 2d: Introduction, Conceptual Approach, ASM 2d, Typical Wastewater Characteristics and Kinetic and Stoichiometric Constants, Limitations, Conclusion ASM 2...
Modeling Flood Disasters: Issues Concerning Data for 2D Numerical Models
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Abdullah Ahmad Fikri
2017-01-01
Full Text Available Flood disasters are one of the worst natural disasters and they occur almost daily. Correspondingly, city managers are nowadays increasingly investing in data collection and modelling activities. Typically, flows in pipes and channels have been modelled using a one-dimensional (1D approach. Also, if the flood flows on the ground are confined to streets and curbs, the use of 1D/1D modelling approach (a.k.a. as dual drainage concept may be a feasible way forward. However, if the flows are two-dimensional with complex interactions taking place through surface/sub-surface links, then the required approach would be the so-called 1D/2D modelling approach. The ever-increasing power of computers is now allowing a 3D fluid dynamics analysis of overflow and manhole structures, and in time these may be coupled with 1D models that may be used in situations where flow characteristics require with higher dimensionality. With the use of 2D models, the importance of terrain data has become a growing issue. The current paper discusses some of the key modelling approaches and makes particular reference to the terrain data processing and collection which can either improve or deteriorate their predictive capability
Simulation of cardiac arrhythmias using a 2D heterogeneous whole heart model
Directory of Open Access Journals (Sweden)
Minimol eBalakrishnan
2015-12-01
Full Text Available Simulation studies of cardiac arrhythmias at the whole heart level with electrocardiogram (ECG gives an understanding of how the underlying cell and tissue level changes manifest as rhythm disturbances in the ECG. We present a 2D whole heart model (WHM2D which can accommodate variations at the cellular level and can generate the ECG waveform. It is shown that, by varying cellular-level parameters like the gap junction conductance (GJC, excitability, action potential duration(APD and frequency of oscillations of the auto-rhythmic cell in WHM2D a large variety of cardiac arrhythmias can be generated including sinus tachycardia, sinus bradycardia, sinus arrhythmia, sinus pause, junctional rhythm, Wolf Parkinson White syndrome and all types of AV conduction blocks. WHM2D includes key components of the electrical conduction system of the heart like the SA (Sino atrial node cells, fast conducting intranodal pathways, slow conducting atriovenctricular (AV node, bundle of His cells, Purkinje network, atrial and ventricular myocardial cells. SA nodal cells, AV nodal cells, bundle of His cells and Purkinje cells are represented by the Fitzhugh-Nagumo (FN model which is a reduced model of the Hodgkin-Huxley neuron model. The atrial and ventricular myocardial cells are modeled by the Aliev-Panfilov (AP two-variable model proposed for cardiac excitation. WHM2D can prove to be a valuable clinical tool for understanding cardiac arrhythmias
(1,q=-1) model as a topological description of 2D string theory
International Nuclear Information System (INIS)
Lavi, Yoav; Oz, Yaron; Sonnenschein, Jacob
1994-01-01
We study the (1,q=-1) model coupled to topological gravity as a candidate to describing 2D string theory at the self-dual radius. We define the model by analytical continuation of q>1 topological recursion relations to q=-1. We show that at genus zero the q=-1 recursion relations yield the W 1+∞ Ward identities for tachyon correlators on the sphere. A scheme for computing correlation functions of q=-1 gravitational descendants is proposed and applied for the computation of several correlators. It is suggested that the latter correspond to correlators of discrete states of the c=1 string. In a similar manner to the q>1 models, we show that there exist topological recursion relations for the correlators in the q=-1 theory that consist of only one and two splittings of the Riemann surface. Using a postulated regularized contact, we prove that the genus one q=-1 recursion relations for tachyon correlators coincide with the W 1+∞ Ward identities on the torus. We argue that the structure of these recursion relations coincides with that of the W 1+∞ Ward identities for any genus. ((orig.))
Hydrodynamic modelling of a tidal delta wetland using an enhanced quasi-2D model
Wester, Sjoerd J.; Grimson, Rafael; Minotti, Priscilla G.; Booija, Martijn J.; Brugnach, Marcela
2018-04-01
Knowledge about the hydrological regime of wetlands is key to understand their physical and biological properties. Modelling hydrological and hydrodynamic processes within a wetland is therefore becoming increasingly important. 3D models have successfully modelled wetland dynamics but depend on very detailed bathymetry and land topography. Many 1D and 2D models of river deltas highly simplify the interaction between the river and wetland area or simply neglect the wetland area. This study proposes an enhanced quasi-2D modelling strategy that captures the interaction between river discharge and moon tides and the resulting hydrodynamics, while using the scarce data available. The water flow equations are discretised with an interconnected irregular cell scheme, in which a simplification of the 1D Saint-Venant equations is used to define the water flow between cells. The spatial structure of wetlands is based on the ecogeomorphology in complex estuarine deltas. The islands within the delta are modelled with levee cells, creek cells and an interior cell representing a shallow marsh wetland. The model is calibrated for an average year and the model performance is evaluated for another average year and additionally an extreme dry three-month period and an extreme wet three-month period. The calibration and evaluation are done based on two water level measurement stations and two discharge measurement stations, all located in the main rivers. Additional calibration is carried out with field water level measurements in a wetland area. Accurate simulations are obtained for both calibration and evaluation with high correlations between observed and simulated water levels and simulated discharges in the same order of magnitude as observed discharges. Calibration against field measurements showed that the model can successfully simulate the overflow mechanism in wetland areas. A sensitivity analysis for several wetland parameters showed that these parameters are all
Comparison of 2D and 3D Models of Salinity Numerical Simulation
Directory of Open Access Journals (Sweden)
Chunhui Li
2015-09-01
Full Text Available For the study of the effect of 2D and 3D mathematical model in salinity simulation, with Liuheng island strong brine discharge of seawater desalination project as an example, using 2D and 3D salinity mathematical models of Liuheng island to simulate coastal hydrodynamic environment and salinity distribution before and after the concentrated brine discharge, and analyzed the results. Finally got the applicable scope of the two models, it has an important significance in the study of similar problems.
2D and 3D modelling of magnetic and resistivity data from Aespoe
International Nuclear Information System (INIS)
Mattsson, Haakan
2011-05-01
This report presents results from modelling of geophysical data. Ground magnetic and geo electric data were collected in 1988 as part of the pre-investigations carried out before the construction of the Aespoe Hard Rock Laboratory (HRL). The work presented in this report is an evaluation of the magnetic and geo electric data with the focus on estimating variations in geometry and dip of some of the possible deformation zones indicated in lineament interpretations presented earlier. This was done by 2D forward magnetic modelling, 2D forward resistivity modelling and 3D inversion of the magnetic data. The specific aims of this work are: 1. Produce magnetic 2D forward models across 12 selected linked lineaments. 2. Produce a 3D susceptibility model of the entire data set of Aespoe. 3. Use 2D forward resistivity modelling to produce electric anomaly response diagrams for a dipole-dipole survey across low resistivity zones with various dips. The results of the modelling work will mainly be used as supportive information for deterministic geological modelling of deformation zones and rock units in the vicinity of the Aespoe HRL. The results of the 2D forward modelling of magnetic data show geologically reasonable solutions, and in most cases it is possible to make reliable estimates of the width and orientation of the cause of the targeted lineament. The possible deformation zones generally dip steeply (80 deg-90 deg) and have a width of c. 30-50 m. In some cases the modelled lineament has a diffuse character with low amplitude, which makes the model solution uncertain. Two 3D susceptibility models were created by use of inversion of the ground magnetic data; one coarse model of the entire Island of Aespoe and one more detailed model of the south-eastern peninsula of the Island, covering the volume of the Aespoe HRL. The two models fit nicely to the measured data and they are geologically realistic. It is possible to identify well-defined bodies (rock volumes) of
Bringing Kano’s Perspective to AHP: The 2D-AHP Decision Model
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Jung Uk
2016-12-01
Full Text Available AHP and the Kano model are such prevalent TQM tools that it may be surprising that a true hybrid decision-making model has so far eluded researchers. The quest for a hybrid approach is complicated by the differing output perspective of each model, namely discrete ranking (AHP versus a multi-dimensional picture (Kano. This paper presents a hybrid model of AHP and Kano model, so called two-dimension AHP (2D-AHP.
Stress Induced Phononic Properties and Surface Waves in 2D Model of Auxetic Crystal
International Nuclear Information System (INIS)
Trzupek, D.; Twarog, D.; Zielinski, P.
2009-01-01
Elastic stiffness parameters are determined in a 2D model system of rigid rods interacting by harmonic force constants. Any positive ('' normal '' crystal) or negative (auxetic crystal) Poisson ratio can be obtained in this model as a function of the external stress. Conditions for opening an absolute stop band (phononic crystal) and for various kinds of surface waves are obtained. (authors)
Evaluation of 2D shallow-water model for spillway flow with a complex geometry
Although the two-dimensional (2D) shallow water model is formulated based on several assumptions such as hydrostatic pressure distribution and vertical velocity is negligible, as a simple alternative to the complex 3D model, it has been used to compute water flows in which these assumptions may be ...
A predictive model for substrates of cytochrome P450-debrisoquine (2D6)
Koymans, L.; Vermeulen, N P; van Acker, S.A.B.E.; te Koppele, J.M.; Heykants, J J; Lavrijsen, K; Meuldermans, W; Donné-Op den Kelder, G M
1992-01-01
Molecular modeling techniques were used to derive a predictive model for substrates of cytochrome P450 2D6, an isozyme known to metabolize only compounds with one or more basic nitrogen atoms. Sixteen substrates, accounting for 23 metabolic reactions, with a distance of either 5 A ("5-A substrates",
Progress in integrated 2-D models for analysis of scrape-off layer transport physics
Energy Technology Data Exchange (ETDEWEB)
Rognlien, T.D. [Lawrence Livermore National Lab., CA (United States); Braams, B.J. [New York Univ., NY (United States); Knoll, D.A. [Idaho National Engineering Lab., Idaho Falls (United States)
1996-08-01
We present the status of comprehensive two-dimensional (2-D) transport modeling for the tokamak scrape-off layer (SOL) using the UEDGE and B2.5 codes. These codes are now able to integrate a variety of physics, including coupling of plasma and neutral transport leading to detachment, complicated diverto-plate geometries, multispecies impurities, and currents and E x B drifts. These new models are outlined and the capabilities are illustrated by a number of examples that emphasize the importance of including the 2-D geometry. (orig.)
The simulation of 3D mass models in 2D digital mammography and breast tomosynthesis.
Shaheen, Eman; De Keyzer, Frederik; Bosmans, Hilde; Dance, David R; Young, Kenneth C; Van Ongeval, Chantal
2014-08-01
This work proposes a new method of building 3D breast mass models with different morphological shapes and describes the validation of the realism of their appearance after simulation into 2D digital mammograms and breast tomosynthesis images. Twenty-five contrast enhanced MRI breast lesions were collected and each mass was manually segmented in the three orthogonal views: sagittal, coronal, and transversal. The segmented models were combined, resampled to have isotropic voxel sizes, triangularly meshed, and scaled to different sizes. These masses were referred to as nonspiculated masses and were then used as nuclei onto which spicules were grown with an iterative branching algorithm forming a total of 30 spiculated masses. These 55 mass models were projected into 2D projection images to obtain mammograms after image processing and into tomographic sequences of projection images, which were then reconstructed to form 3D tomosynthesis datasets. The realism of the appearance of these mass models was assessed by five radiologists via receiver operating characteristic (ROC) analysis when compared to 54 real masses. All lesions were also given a breast imaging reporting and data system (BIRADS) score. The data sets of 2D mammography and tomosynthesis were read separately. The Kendall's coefficient of concordance was used for the interrater observer agreement assessment for the BIRADS scores per modality. Further paired analysis, using the Wilcoxon signed rank test, of the BIRADS assessment between 2D and tomosynthesis was separately performed for the real masses and for the simulated masses. The area under the ROC curves, averaged over all observers, was 0.54 (95% confidence interval [0.50, 0.66]) for the 2D study, and 0.67 (95% confidence interval [0.55, 0.79]) for the tomosynthesis study. According to the BIRADS scores, the nonspiculated and the spiculated masses varied in their degrees of malignancy from normal (BIRADS 1) to highly suggestive for malignancy (BIRADS 5
The simulation of 3D mass models in 2D digital mammography and breast tomosynthesis
Energy Technology Data Exchange (ETDEWEB)
Shaheen, Eman, E-mail: eman.shaheen@uzleuven.be; De Keyzer, Frederik; Bosmans, Hilde; Ongeval, Chantal Van [Department of Radiology, University Hospitals Leuven, Herestraat 49, 3000 Leuven (Belgium); Dance, David R.; Young, Kenneth C. [National Coordinating Centre for the Physics of Mammography, Royal Surrey County Hospital, Guildford GU2 7XX, United Kingdom and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom)
2014-08-15
Purpose: This work proposes a new method of building 3D breast mass models with different morphological shapes and describes the validation of the realism of their appearance after simulation into 2D digital mammograms and breast tomosynthesis images. Methods: Twenty-five contrast enhanced MRI breast lesions were collected and each mass was manually segmented in the three orthogonal views: sagittal, coronal, and transversal. The segmented models were combined, resampled to have isotropic voxel sizes, triangularly meshed, and scaled to different sizes. These masses were referred to as nonspiculated masses and were then used as nuclei onto which spicules were grown with an iterative branching algorithm forming a total of 30 spiculated masses. These 55 mass models were projected into 2D projection images to obtain mammograms after image processing and into tomographic sequences of projection images, which were then reconstructed to form 3D tomosynthesis datasets. The realism of the appearance of these mass models was assessed by five radiologists via receiver operating characteristic (ROC) analysis when compared to 54 real masses. All lesions were also given a breast imaging reporting and data system (BIRADS) score. The data sets of 2D mammography and tomosynthesis were read separately. The Kendall's coefficient of concordance was used for the interrater observer agreement assessment for the BIRADS scores per modality. Further paired analysis, using the Wilcoxon signed rank test, of the BIRADS assessment between 2D and tomosynthesis was separately performed for the real masses and for the simulated masses. Results: The area under the ROC curves, averaged over all observers, was 0.54 (95% confidence interval [0.50, 0.66]) for the 2D study, and 0.67 (95% confidence interval [0.55, 0.79]) for the tomosynthesis study. According to the BIRADS scores, the nonspiculated and the spiculated masses varied in their degrees of malignancy from normal (BIRADS 1) to highly
The simulation of 3D mass models in 2D digital mammography and breast tomosynthesis
International Nuclear Information System (INIS)
Shaheen, Eman; De Keyzer, Frederik; Bosmans, Hilde; Ongeval, Chantal Van; Dance, David R.; Young, Kenneth C.
2014-01-01
Purpose: This work proposes a new method of building 3D breast mass models with different morphological shapes and describes the validation of the realism of their appearance after simulation into 2D digital mammograms and breast tomosynthesis images. Methods: Twenty-five contrast enhanced MRI breast lesions were collected and each mass was manually segmented in the three orthogonal views: sagittal, coronal, and transversal. The segmented models were combined, resampled to have isotropic voxel sizes, triangularly meshed, and scaled to different sizes. These masses were referred to as nonspiculated masses and were then used as nuclei onto which spicules were grown with an iterative branching algorithm forming a total of 30 spiculated masses. These 55 mass models were projected into 2D projection images to obtain mammograms after image processing and into tomographic sequences of projection images, which were then reconstructed to form 3D tomosynthesis datasets. The realism of the appearance of these mass models was assessed by five radiologists via receiver operating characteristic (ROC) analysis when compared to 54 real masses. All lesions were also given a breast imaging reporting and data system (BIRADS) score. The data sets of 2D mammography and tomosynthesis were read separately. The Kendall's coefficient of concordance was used for the interrater observer agreement assessment for the BIRADS scores per modality. Further paired analysis, using the Wilcoxon signed rank test, of the BIRADS assessment between 2D and tomosynthesis was separately performed for the real masses and for the simulated masses. Results: The area under the ROC curves, averaged over all observers, was 0.54 (95% confidence interval [0.50, 0.66]) for the 2D study, and 0.67 (95% confidence interval [0.55, 0.79]) for the tomosynthesis study. According to the BIRADS scores, the nonspiculated and the spiculated masses varied in their degrees of malignancy from normal (BIRADS 1) to highly
Impact of high speed civil transports on stratospheric ozone. A 2-D model investigation
Energy Technology Data Exchange (ETDEWEB)
Kinnison, D.E.; Connell, P.S. [Lawrence Livermore National Lab., CA (United States)
1997-12-31
This study investigates the effect on stratospheric ozone from a fleet of proposed High Speed Civil Transports (HSCTs). The new LLNL 2-D operator-split chemical-radiative-transport model of the troposphere and stratosphere is used for this HSCT investigation. This model is integrated in a diurnal manner, using an implicit numerical solver. Therefore, rate coefficients are not modified by any sort of diurnal average factor. This model also does not make any assumptions on lumping of chemical species into families. Comparisons to previous model-derived HSCT assessment of ozone change are made, both to the previous LLNL 2-D model and to other models from the international assessment modeling community. The sensitivity to the NO{sub x} emission index and sulfate surface area density is also explored. (author) 7 refs.
Die Moran, Andres; El kadi Abderrezzak, Kamal; Tassi, Pablo; Herouvet, Jean-Michel
2014-05-01
Bank erosion is a key process that may cause a large number of economic and environmental problems (e.g. land loss, damage to structures and aquatic habitat). Stream bank erosion (toe erosion and mass failure) represents an important form of channel morphology changes and a significant source of sediment. With the advances made in computational techniques, two-dimensional (2-D) numerical models have become valuable tools for investigating flow and sediment transport in open channels at large temporal and spatial scales. However, the implementation of mass failure process in 2D numerical models is still a challenging task. In this paper, a simple, innovative algorithm is implemented in the Telemac-Mascaret modeling platform to handle bank failure: failure occurs whether the actual slope of one given bed element is higher than the internal friction angle. The unstable bed elements are rotated around an appropriate axis, ensuring mass conservation. Mass failure of a bank due to slope instability is applied at the end of each sediment transport evolution iteration, once the bed evolution due to bed load (and/or suspended load) has been computed, but before the global sediment mass balance is verified. This bank failure algorithm is successfully tested using two laboratory experimental cases. Then, bank failure in a 1:40 scale physical model of the Rhine River composed of non-uniform material is simulated. The main features of the bank erosion and failure are correctly reproduced in the numerical simulations, namely the mass wasting at the bank toe, followed by failure at the bank head, and subsequent transport of the mobilised material in an aggradation front. Volumes of eroded material obtained are of the same order of magnitude as the volumes measured during the laboratory tests.
2D MHD AND 1D HD MODELS OF A SOLAR FLARE—A COMPREHENSIVE COMPARISON OF THE RESULTS
Energy Technology Data Exchange (ETDEWEB)
Falewicz, R.; Rudawy, P. [Astronomical Institute, University of Wrocław, 51-622 Wrocław, ul. Kopernika 11 (Poland); Murawski, K. [Group of Astrophysics, UMCS, ul. Radziszewskiego 10, 20-031 Lublin (Poland); Srivastava, A. K., E-mail: falewicz@astro.uni.wroc.pl, E-mail: rudawy@astro.uni.wroc.pl, E-mail: kmur@kft.umcs.lublin.pl, E-mail: asrivastava.app@iitbhu.ac.in [Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi-221005 (India)
2015-11-01
Without any doubt, solar flaring loops possess a multithread internal structure that is poorly resolved, and there are no means to observe heating episodes and thermodynamic evolution of the individual threads. These limitations cause fundamental problems in numerical modeling of flaring loops, such as selection of a structure and a number of threads, and an implementation of a proper model of the energy deposition process. A set of one-dimensional (1D) hydrodynamic and two-dimensional (2D) magnetohydrodynamic models of a flaring loop are developed to compare energy redistribution and plasma dynamics in the course of a prototypical solar flare. Basic parameters of the modeled loop are set according to the progenitor M1.8 flare recorded in AR 10126 on 2002 September 20 between 09:21 UT and 09:50 UT. The nonideal 1D models include thermal conduction and radiative losses of the optically thin plasma as energy-loss mechanisms, while the nonideal 2D models take into account viscosity and thermal conduction as energy-loss mechanisms only. The 2D models have a continuous distribution of the parameters of the plasma across the loop and are powered by varying in time and space along and across the loop heating flux. We show that such 2D models are an extreme borderline case of a multithread internal structure of the flaring loop, with a filling factor equal to 1. Nevertheless, these simple models ensure the general correctness of the obtained results and can be adopted as a correct approximation of the real flaring structures.
A simple model for 2D image upconversion of incoherent light
DEFF Research Database (Denmark)
Dam, Jeppe Seidelin; Pedersen, Christian; Tidemand-Lichtenberg, Peter
2011-01-01
We present a simple theoretical model for 2 dimensional (2-D) image up-conversion of incoherent light. While image upconversion has been known for more than 40 years, the technology has been hindered by very low conversion quantum efficiency (~10-7). We show that our implementation compared...
A preliminary 3D model for cytochrome P450 2D6 constructed by homology model building
Koymans, L M; Vermeulen, N P; Baarslag, A; Donné-Op den Kelder, G M
A homology model building study of cytochrome P450 2D6 has been carried out based on the crystal structure of cytochrome P450 101. The primary sequences of P450 101 and P450 2D6 were aligned by making use of an automated alignment procedure. This alignment was adjusted manually by matching
Activated sludge models ASM1, ASM2, ASM2d and ASM3
DEFF Research Database (Denmark)
Henze, Mogens; Gujer, W.; Mino, T.
sludge processes has become a common part of the design and operation of wastewater treatment plants. Today models are being used in design, control, teaching and research.ContentsASM3: Introduction, Comparison of ASM1 and ASM3, ASM3: Definition of compounds in the model, ASM3: Definition of processes...... in the Model, ASM3: Stoichiometry, ASM3: Kinetics, Limitations of ASM3, Aspects of application of ASM3, ASM3C: A Carbon based model, Conclusion ASM 2d: Introduction, Conceptual Approach, ASM 2d, Typical Wastewater Characteristics and Kinetic and Stoichiometric Constants, Limitations, Conclusion ASM 2...... Oxidation Nitrification and Denitrification, Characterization of Wastewater and Estimation of Parameter Values, Typical Parameter Ranges, Default Values, and Effects of Environmental Factors, Assumptions, Restrictions and Constraints, Implementation of the Activated Sludge Model...
A deformed shape monitoring model for building structures based on a 2D laser scanner.
Choi, Se Woon; Kim, Bub Ryur; Lee, Hong Min; Kim, Yousok; Park, Hyo Seon
2013-05-21
High-rise buildings subjected to lateral loads such as wind and earthquake loads must be checked not to exceed the limits on the maximum lateral displacement or the maximum inter-story drift ratios. In this paper, a sensing model for deformed shapes of a building structure in motion is presented. The deformed shape sensing model based on a 2D scanner consists of five modules: (1) module for acquiring coordinate information of a point in a building; (2) module for coordinate transformation and data arrangement for generation of time history of the point; (3) module for smoothing by adjacent averaging technique; (4) module for generation of the displacement history for each story and deformed shape of a building, and (5) module for evaluation of the serviceability of a building. The feasibility of the sensing model based on a 2D laser scanner is tested through free vibration tests of a three-story steel frame structure with a relatively high slenderness ratio of 5.0. Free vibration responses measured from both laser displacement sensors and a 2D laser scanner are compared. In the experimentation, the deformed shapes were obtained from three different methods: the model based on the 2D laser scanner, the direct measurement based on laser displacement sensors, and the numerical method using acceleration data and the displacements from GPS. As a result, it is confirmed that the deformed shape measurement model based on a 2D laser scanner can be a promising alternative for high-rise buildings where installation of laser displacement sensors is impossible.
A 1D-2D coupled SPH-SWE model applied to open channel flow simulations in complicated geometries
Chang, Kao-Hua; Sheu, Tony Wen-Hann; Chang, Tsang-Jung
2018-05-01
In this study, a one- and two-dimensional (1D-2D) coupled model is developed to solve the shallow water equations (SWEs). The solutions are obtained using a Lagrangian meshless method called smoothed particle hydrodynamics (SPH) to simulate shallow water flows in converging, diverging and curved channels. A buffer zone is introduced to exchange information between the 1D and 2D SPH-SWE models. Interpolated water discharge values and water surface levels at the internal boundaries are prescribed as the inflow/outflow boundary conditions in the two SPH-SWE models. In addition, instead of using the SPH summation operator, we directly solve the continuity equation by introducing a diffusive term to suppress oscillations in the predicted water depth. The performance of the two approaches in calculating the water depth is comprehensively compared through a case study of a straight channel. Additionally, three benchmark cases involving converging, diverging and curved channels are adopted to demonstrate the ability of the proposed 1D and 2D coupled SPH-SWE model through comparisons with measured data and predicted mesh-based numerical results. The proposed model provides satisfactory accuracy and guaranteed convergence.
Modeling human diseases with induced pluripotent stem cells: from 2D to 3D and beyond.
Liu, Chun; Oikonomopoulos, Angelos; Sayed, Nazish; Wu, Joseph C
2018-03-08
The advent of human induced pluripotent stem cells (iPSCs) presents unprecedented opportunities to model human diseases. Differentiated cells derived from iPSCs in two-dimensional (2D) monolayers have proven to be a relatively simple tool for exploring disease pathogenesis and underlying mechanisms. In this Spotlight article, we discuss the progress and limitations of the current 2D iPSC disease-modeling platform, as well as recent advancements in the development of human iPSC models that mimic in vivo tissues and organs at the three-dimensional (3D) level. Recent bioengineering approaches have begun to combine different 3D organoid types into a single '4D multi-organ system'. We summarize the advantages of this approach and speculate on the future role of 4D multi-organ systems in human disease modeling. © 2018. Published by The Company of Biologists Ltd.
Reliability of a Novel Model for Drug Release from 2D HPMC-Matrices
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Rumiana Blagoeva
2010-04-01
Full Text Available A novel model of drug release from 2D-HPMC matrices is considered. Detailed mathematical description of matrix swelling and the effect of the initial drug loading are introduced. A numerical approach to solution of the posed nonlinear 2D problem is used on the basis of finite element domain approximation and time difference method. The reliability of the model is investigated in two steps: numerical evaluation of the water uptake parameters; evaluation of drug release parameters under available experimental data. The proposed numerical procedure for fitting the model is validated performing different numerical examples of drug release in two cases (with and without taking into account initial drug loading. The goodness of fit evaluated by the coefficient of determination is presented to be very good with few exceptions. The obtained results show better model fitting when accounting the effect of initial drug loading (especially for larger values.
Mapping the Habitable Zone of Exoplanets with a 2D Energy Balance Model
Moon, Nicole Taylor; Dr. Lisa Kaltenegger, Dr. Ramses Ramirez
2018-01-01
Traditionally, the habitable zone has been defined as the distance at which liquid water could exist on the surface of a rocky planet. However, different complexity models (simplified and fast:1D, and complex and time-intense:3D) models derive different boundaries for the habitable zone. The goal of this project was to test a new intermediate complexity 2D Energy Balance model, add a new ice albedo feedback mechanism, and derive the habitable zone boundaries. After completing this first project, we also studied how other feedback mechanisms, such as the presence of clouds and the carbonate-silicate cycle, effected the location of the habitable zone boundaries using this 2D model. This project was completed as part of a 2017 summer REU program hosted by Cornell's Center for Astrophysics and Plantary Sciecne and in partnership with the Carl Sagan Institute.
arXiv Topology in the 2d Heisenberg Model under Gradient Flow
Sandoval, Ilya O.; de Forcrand, Philippe; Gerber, Urs; Mejía-Díaz, Héctor
2017-10-28
The 2d Heisenberg model — or 2d O(3) model — is popular in condensed matter physics, and in particle physics as a toy model for QCD. Along with other analogies, it shares with 4d Yang-Mills theories, and with QCD, the property that the configurations are divided in topological sectors. In the lattice regularisation the topological charge Q can still be defined such that $Q\\in \\mathbb{Z}$. It has generally been observed, however, that the topological susceptibility ${{\\chi }_{t}}=\\langle {{Q}^{2}}\\rangle /V$ does not scale properly in the continuum limit, i.e. that the quantity ${{\\chi }_{t}}{{\\xi }^{2}}$ diverges for ξ → ∞ (where ξ is the correlation length in lattice units). Here we address the question whether or not this divergence persists after the application of the Gradient Flow.
COMPARISON BETWEEN 2D TURBULENCE MODEL ESEL AND EXPERIMENTAL DATA FROM AUG AND COMPASS TOKAMAKS
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Peter Ondac
2015-04-01
Full Text Available In this article we have used the 2D fluid turbulence numerical model, ESEL, to simulate turbulent transport in edge tokamak plasma. Basic plasma parameters from the ASDEX Upgrade and COMPASS tokamaks are used as input for the model, and the output is compared with experimental observations obtained by reciprocating probe measurements from the two machines. Agreements were found in radial profiles of mean plasma potential and temperature, and in a level of density fluctuations. Disagreements, however, were found in the level of plasma potential and temperature fluctuations. This implicates a need for an extension of the ESEL model from 2D to 3D to fully resolve the parallel dynamics, and the coupling from the plasma to the sheath.
Elliptic genera of 2d (0,2) gauge theories from brane brick models
Franco, Sebastian; Ghim, Dongwook; Lee, Sangmin; Seong, Rak-Kyeong
2017-06-01
Auc(bstract) We compute the elliptic genus of abelian 2d (0, 2) gauge theories corresponding to brane brick models. These theories are worldvolume theories on a single D1-brane probing a toric Calabi-Yau 4-fold singularity. We identify a match with the elliptic genus of the non-linear sigma model on the same Calabi-Yau background, which is computed using a new localization formula. The matching implies that the quantum effects do not drastically alter the correspondence between the geometry and the 2d (0, 2) gauge theory. In theories whose matter sector suffers from abelian gauge anomaly, we propose an ansatz for an anomaly cancelling term in the integral formula for the elliptic genus. We provide an example in which two brane brick models related to each other by Gadde-Gukov-Putrov triality give the same elliptic genus.
1D and 2D urban dam-break flood modelling in Istanbul, Turkey
Ozdemir, Hasan; Neal, Jeffrey; Bates, Paul; Döker, Fatih
2014-05-01
Urban flood events are increasing in frequency and severity as a consequence of several factors such as reduced infiltration capacities due to continued watershed development, increased construction in flood prone areas due to population growth, the possible amplification of rainfall intensity due to climate change, sea level rise which threatens coastal development, and poorly engineered flood control infrastructure (Gallegos et al., 2009). These factors will contribute to increased urban flood risk in the future, and as a result improved modelling of urban flooding according to different causative factor has been identified as a research priority (Gallegos et al., 2009; Ozdemir et al. 2013). The flooding disaster caused by dam failures is always a threat against lives and properties especially in urban environments. Therefore, the prediction of dynamics of dam-break flows plays a vital role in the forecast and evaluation of flooding disasters, and is of long-standing interest for researchers. Flooding occurred on the Ayamama River (Istanbul-Turkey) due to high intensity rainfall and dam-breaching of Ata Pond in 9th September 2009. The settlements, industrial areas and transportation system on the floodplain of the Ayamama River were inundated. Therefore, 32 people were dead and millions of Euros economic loses were occurred. The aim of this study is 1 and 2-Dimensional flood modelling of the Ata Pond breaching using HEC-RAS and LISFLOOD-Roe models and comparison of the model results using the real flood extent. The HEC-RAS model solves the full 1-D Saint Venant equations for unsteady open channel flow whereas LISFLOOD-Roe is the 2-D shallow water model which calculates the flow according to the complete Saint Venant formulation (Villanueva and Wright, 2006; Neal et al., 2011). The model consists a shock capturing Godunov-type scheme based on the Roe Riemann solver (Roe, 1981). 3 m high resolution Digital Surface Model (DSM), natural characteristics of the pond
TRENT2D WG: a smart web infrastructure for debris-flow modelling and hazard assessment
Zorzi, Nadia; Rosatti, Giorgio; Zugliani, Daniel; Rizzi, Alessandro; Piffer, Stefano
2016-04-01
Mountain regions are naturally exposed to geomorphic flows, which involve large amounts of sediments and induce significant morphological modifications. The physical complexity of this class of phenomena represents a challenging issue for modelling, leading to elaborate theoretical frameworks and sophisticated numerical techniques. In general, geomorphic-flows models proved to be valid tools in hazard assessment and management. However, model complexity seems to represent one of the main obstacles to the diffusion of advanced modelling tools between practitioners and stakeholders, although the UE Flood Directive (2007/60/EC) requires risk management and assessment to be based on "best practices and best available technologies". Furthermore, several cutting-edge models are not particularly user-friendly and multiple stand-alone software are needed to pre- and post-process modelling data. For all these reasons, users often resort to quicker and rougher approaches, leading possibly to unreliable results. Therefore, some effort seems to be necessary to overcome these drawbacks, with the purpose of supporting and encouraging a widespread diffusion of the most reliable, although sophisticated, modelling tools. With this aim, this work presents TRENT2D WG, a new smart modelling solution for the state-of-the-art model TRENT2D (Armanini et al., 2009, Rosatti and Begnudelli, 2013), which simulates debris flows and hyperconcentrated flows adopting a two-phase description over a mobile bed. TRENT2D WG is a web infrastructure joining advantages offered by the software-delivering model SaaS (Software as a Service) and by WebGIS technology and hosting a complete and user-friendly working environment for modelling. In order to develop TRENT2D WG, the model TRENT2D was converted into a service and exposed on a cloud server, transferring computational burdens from the user hardware to a high-performing server and reducing computational time. Then, the system was equipped with an
Fekkes, Stein; Swillens, Abigail E S; Hansen, Hendrik H G; Saris, Anne E C M; Nillesen, Maartje M; Iannaccone, Francesco; Segers, Patrick; de Korte, Chris L
2016-10-01
Three-dimensional (3-D) strain estimation might improve the detection and localization of high strain regions in the carotid artery (CA) for identification of vulnerable plaques. This paper compares 2-D versus 3-D displacement estimation in terms of radial and circumferential strain using simulated ultrasound (US) images of a patient-specific 3-D atherosclerotic CA model at the bifurcation embedded in surrounding tissue generated with ABAQUS software. Global longitudinal motion was superimposed to the model based on the literature data. A Philips L11-3 linear array transducer was simulated, which transmitted plane waves at three alternating angles at a pulse repetition rate of 10 kHz. Interframe (IF) radio-frequency US data were simulated in Field II for 191 equally spaced longitudinal positions of the internal CA. Accumulated radial and circumferential displacements were estimated using tracking of the IF displacements estimated by a two-step normalized cross-correlation method and displacement compounding. Least-squares strain estimation was performed to determine accumulated radial and circumferential strain. The performance of the 2-D and 3-D methods was compared by calculating the root-mean-squared error of the estimated strains with respect to the reference strains obtained from the model. More accurate strain images were obtained using the 3-D displacement estimation for the entire cardiac cycle. The 3-D technique clearly outperformed the 2-D technique in phases with high IF longitudinal motion. In fact, the large IF longitudinal motion rendered it impossible to accurately track the tissue and cumulate strains over the entire cardiac cycle with the 2-D technique.
Fekkes, Stein; Swillens, Abigail E S; Hansen, Hendrik H G; Saris, Anne E C M; Nillesen, Maartje M; Iannaccone, Francesco; Segers, Patrick; de Korte, Chris L
2016-08-25
Three-dimensional strain estimation might improve the detection and localization of high strain regions in the carotid artery for identification of vulnerable plaques. This study compares 2D vs. 3D displacement estimation in terms of radial and circumferential strain using simulated ultrasound images of a patient specific 3D atherosclerotic carotid artery model at the bifurcation embedded in surrounding tissue generated with ABAQUS software. Global longitudinal motion was superimposed to the model based on literature data. A Philips L11-3 linear array transducer was simulated which transmitted plane waves at 3 alternating angles at a pulse repetition rate of 10 kHz. Inter-frame radiofrequency ultrasound data were simulated in Field II for 191 equally spaced longitudinal positions of the internal carotid artery. Accumulated radial and circumferential displacements were estimated using tracking of the inter-frame displacements estimated by a two-step normalized cross-correlation method and displacement compounding. Least squares strain estimation was performed to determine accumulated radial and circumferential strain. The performance of the 2D and 3D method was compared by calculating the root-mean-squared error of the estimated strains with respect to the reference strains obtained from the model. More accurate strain images were obtained using the 3D displacement estimation for the entire cardiac cycle. The 3D technique clearly outperformed the 2D technique in phases with high inter-frame longitudinal motion. In fact the large inter-frame longitudinal motion rendered it impossible to accurately track the tissue and cumulate strains over the entire cardiac cycle with the 2D technique.
Parameterising root system growth models using 2D neutron radiography images
Schnepf, Andrea; Felderer, Bernd; Vontobel, Peter; Leitner, Daniel
2013-04-01
Root architecture is a key factor for plant acquisition of water and nutrients from soil. In particular in view of a second green revolution where the below ground parts of agricultural crops are important, it is essential to characterise and quantify root architecture and its effect on plant resource acquisition. Mathematical models can help to understand the processes occurring in the soil-plant system, they can be used to quantify the effect of root and rhizosphere traits on resource acquisition and the response to environmental conditions. In order to do so, root architectural models are coupled with a model of water and solute transport in soil. However, dynamic root architectural models are difficult to parameterise. Novel imaging techniques such as x-ray computed tomography, neutron radiography and magnetic resonance imaging enable the in situ visualisation of plant root systems. Therefore, these images facilitate the parameterisation of dynamic root architecture models. These imaging techniques are capable of producing 3D or 2D images. Moreover, 2D images are also available in the form of hand drawings or from images of standard cameras. While full 3D imaging tools are still limited in resolutions, 2D techniques are a more accurate and less expensive option for observing roots in their environment. However, analysis of 2D images has additional difficulties compared to the 3D case, because of overlapping roots. We present a novel algorithm for the parameterisation of root system growth models based on 2D images of root system. The algorithm analyses dynamic image data. These are a series of 2D images of the root system at different points in time. Image data has already been adjusted for missing links and artefacts and segmentation was performed by applying a matched filter response. From this time series of binary 2D images, we parameterise the dynamic root architecture model in the following way: First, a morphological skeleton is derived from the binary
Validation of a 2-D semi-coupled numerical model for fluid-structure-seabed interaction
Ye, Jianhong; Jeng, Dongsheng; Wang, Ren; Zhu, Changqi
2013-10-01
A 2-D semi-coupled model PORO-WSSI 2D (also be referred as FSSI-CAS 2D) for the Fluid-Structure-Seabed Interaction (FSSI) has been developed by employing RANS equations for wave motion in fluid domain, VARANS equations for porous flow in porous structures; and taking the dynamic Biot's equations (known as "u - p" approximation) for soil as the governing equations. The finite difference two-step projection method and the forward time difference method are adopted to solve the RANS, VARANS equations; and the finite element method is adopted to solve the "u - p" approximation. A data exchange port is developed to couple the RANS, VARANS equations and the dynamic Biot's equations together. The analytical solution proposed by Hsu and Jeng (1994) and some experiments conducted in wave flume or geotechnical centrifuge in which various waves involved are used to validate the developed semi-coupled numerical model. The sandy bed involved in these experiments is poro-elastic or poro-elastoplastic. The inclusion of the interaction between fluid, marine structures and poro-elastoplastic seabed foundation is a special point and highlight in this paper, which is essentially different with other previous coupled models The excellent agreement between the numerical results and the experiment data indicates that the developed coupled model is highly reliablefor the FSSI problem.
Hybrid 2D-3D modelling of GTA welding with filler wire addition
Traidia, Abderrazak
2012-07-01
A hybrid 2D-3D model for the numerical simulation of Gas Tungsten Arc welding is proposed in this paper. It offers the possibility to predict the temperature field as well as the shape of the solidified weld joint for different operating parameters, with relatively good accuracy and reasonable computational cost. Also, an original approach to simulate the effect of immersing a cold filler wire in the weld pool is presented. The simulation results reveal two important observations. First, the weld pool depth is locally decreased in the presence of filler metal, which is due to the energy absorption by the cold feeding wire from the hot molten pool. In addition, the weld shape, maximum temperature and thermal cycles in the workpiece are relatively well predicted even when a 2D model for the arc plasma region is used. © 2012 Elsevier Ltd. All rights reserved.
A 2D model of causal set quantum gravity: the emergence of the continuum
International Nuclear Information System (INIS)
Brightwell, Graham; Henson, Joe; Surya, Sumati
2008-01-01
Non-perturbative theories of quantum gravity inevitably include configurations that fail to resemble physically reasonable spacetimes at large scales. Often, these configurations are entropically dominant and pose an obstacle to obtaining the desired classical limit. We examine this 'entropy problem' in a model of causal set quantum gravity corresponding to a discretization of 2D spacetimes. Using results from the theory of partial orders we show that, in the large volume or continuum limit, its partition function is dominated by causal sets which approximate to a region of 2D Minkowski space. This model of causal set quantum gravity thus overcomes the entropy problem and predicts the emergence of a physically reasonable geometry
Directory of Open Access Journals (Sweden)
Dejun Yang
Full Text Available ABSTRACT Simulations for root growth, crop growth, and N uptake in agro-hydrological models are of significant concern to researchers. SWMS_2D is one of the most widely used physical hydrologically related models. This model solves equations that govern soil-water movement by the finite element method, and has a public access source code. Incorporating key agricultural components into the SWMS_2D model is of practical importance, especially for modeling some critical cereal crops such as winter wheat. We added root growth, crop growth, and N uptake modules into SWMS_2D. The root growth model had two sub-models, one for root penetration and the other for root length distribution. The crop growth model used was adapted from EU-ROTATE_N, linked to the N uptake model. Soil-water limitation, nitrogen limitation, and temperature effects were all considered in dry-weight modeling. Field experiments for winter wheat in Bouwing, the Netherlands, in 1983-1984 were selected for validation. Good agreements were achieved between simulations and measurements, including soil water content at different depths, normalized root length distribution, dry weight and nitrogen uptake. This indicated that the proposed new modules used in the SWMS_2D model are robust and reliable. In the future, more rigorous validation should be carried out, ideally under 2D situations, and attention should be paid to improve some modules, including the module simulating soil N mineralization.
Climate impact of aircraft emissions in the upper troposphere. Studies with a 2D-model
Energy Technology Data Exchange (ETDEWEB)
Schmitz, G.; Gabriel, A.; Gepraegs, R. [Institut fuer Atmosphaerenphysik, Kuehlungsborn (Germany)
1997-12-01
A new efficient interactive dynamical-chemical radiative 2D-model based on the standard climate 3D-GCM ECHAM3 and a coupled NCAR chemistry module was developed to study the climate impact of aircraft emissions. The main feature of the 2D-model is a selfconsistent parameterization of the tropospheric eddy heat and momentum fluxes. Assuming perpetual January conditions, the results give a realistic picture of the zonally averaged meridional mass circulation, the tracer transport and the chemistry. In this case, the NO{sub x} background concentrations depend on the composition of downward sinking lower stratospheric air masses and on the tropopause structure in northern winter midlatitudes. The inclusion of zonally averaged January civil aircraft NO{sub x} emissions leads to a positive maximum disturbance in the NO{sub x} mixing ratio of about 60 ppt (50%) in the area of the maximum of the aircraft emissions and induces a positive change in the upper tropospheric O{sub x} mixing ratio of about 1-1.5 ppb (1%). The advantage of the 2D-model is the more efficiency in carrying out further dynamical-chemical coupled sensitivity studies giving a better understanding of the dynamical-chemical interactions and the climatic features of both the background and the disturbed atmosphere. (orig.) 144 figs., 42 tabs., 497 refs.
Edge-Corrected Mean-Field Hubbard Model: Principle and Applications in 2D Materials
Zhang, Xi; Wang, Tianlei; Chen, Wencong; Wang, Sanmei; Peng, Da
2017-05-01
This work reviews the current progress of tight-binding methods and the recent edge-modified mean-field Hubbard model. Undercoordinated atoms and nonbonding electrons exist widely in nanomaterials and in network-structural materials with their impact under-estimated. A quantum theory was proposed to calculate the under-coordinated effects on the electronic structure of materials by incorporating bond order-length-strength (BOLS) correlation theory to mean-field Hubbard model, i.e. BOLS-HM. Consistency between the BOLS-HM calculation and density functional theory (DFT) calculation on 2D materials verified that i) bond contractions and potential well depression occur at the edge of graphene, phosphorene, and antimonene nanoribbons; ii) the physical origin of the band gap opening of graphene, phosphorene, and antimonene nanoribbons lays in the enhancement of edge potentials and hopping integrals due to the shorter and stronger bonds between undercoordinated atoms; iii) the band gap of 2D material nanoribbons expand as the width decreases due to the increasing under-coordination effects of edges which modulates the conductive behaviors; and iv) nonbond electrons at the edges and atomic vacancies of 2D material accompanied with the broken bond contribute to the Dirac-Fermi polaron (DFP) with a local magnetic moment.
Micropolar curved rods. 2-D, high order, Timoshenko’s and Euler-Bernoulli models
Directory of Open Access Journals (Sweden)
Zozulya V.V.
2017-01-01
Full Text Available New models for micropolar plane curved rods have been developed. 2-D theory is developed from general 2-D equations of linear micropolar elasticity using a special curvilinear system of coordinates related to the middle line of the rod and special hypothesis based on assumptions that take into account the fact that the rod is thin.High order theory is based on the expansion of the equations of the theory of elasticity into Fourier series in terms of Legendre polynomials. First stress and strain tensors,vectors of displacements and rotation and body force shave been expanded into Fourier series in terms of Legendre polynomials with respect to a thickness coordinate.Thereby all equations of elasticity including Hooke’s law have been transformed to the corresponding equations for Fourier coefficients. Then in the same way as in the theory of elasticity, system of differential equations in term of displacements and boundary conditions for Fourier coefficients have been obtained. The Timoshenko’s and Euler-Bernoulli theories are based on the classical hypothesis and 2-D equations of linear micropolar elasticity in a special curvilinear system. The obtained equations can be used to calculate stress-strain and to model thin walled structures in macro, micro and nano scale when taking in to account micropolar couple stress and rotation effects.
Edge-Corrected Mean-Field Hubbard Model: Principle and Applications in 2D Materials
Directory of Open Access Journals (Sweden)
Xi Zhang
2017-05-01
Full Text Available This work reviews the current progress of tight-binding methods and the recent edge-modified mean-field Hubbard model. Undercoordinated atoms (atoms not fully coordinated exist at a high rate in nanomaterials with their impact overlooked. A quantum theory was proposed to calculate electronic structure of nanomaterials by incorporating bond order-length-strength (BOLS correlation to mean-field Hubbard model, i.e., BOLS-HM. Consistency between the BOLS-HM calculation and density functional theory (DFT calculation on 2D materials verified that (i bond contractions and potential well depression occur at the edge of graphene, phosphorene, and antimonene nanoribbons; (ii the physical origin of the band gap opening of graphene, phosphorene, and antimonene nanoribbons lays in the enhancement of edge potentials and hopping integrals due to the shorter and stronger bonds between undercoordinated atoms; (iii the band gap of 2D material nanoribbons expand as the width decreases due to the increasing under-coordination effects of edges which modulates the conductive behaviors; and (iv non-bond electrons at the edges and atomic vacancies of 2D material accompanied with the broken bond contribute to the Dirac-Fermi polaron (DFP with a local magnetic moment.
2-D Petroleum System Modelling of the Browse Basin, Offshore Northwestern Australia
Son, Byeong-Kook
2017-04-01
Petroleum system modelling was performed for the Browse Basin, which is a hydrocarbon-bearing basin in the offshore area of northwestern Australia. The Browse Basin was formed by two cycles of tectonically controlled extension, thermal subsidence, and inversion. The first rifting had occurred by the extension in the Late Carboniferous to Early Permian, and the second was in the Early to Middle Jurassic. Thick sediments were deposited during subsequent subsidence and inversion in the basin. The Upper Jurassic to Lower Cretaceous succession is considered to have the high quality source potential. Major reservoirs are fluvio-deltaic and nearshore marine sandstone units in the Jurassic and Cretaceous. Late Cretaceous to Tertiary sequences are dominated by thick carbonate rocks. Maturity model and paleo-heat flow history were made in 1-D petroleum system modelling by comparing with vitrinite values and temperature measured from the drill wells. Based on the geologic setting and the 1-D model, 2-D Petroleum system modelling was conducted on an E-W cross section crossing three wells to understand hydrocarbon generation, migration, and accumulation in the basin. Late Jurassic to Early Cretaceous formations, including Aptian, Vlanginian, and Callovian rocks, were assigned as source rocks in the 2-D modelling. The 2-D model shows that hydrocarbons were generated during Late Jurassic to Late Cretaceous. A thick succession of overburden rocks provided the source rocks with heat and pressure to generate a significant amount of hydrocarbons. Hydrocarbons expelled from the source rocks were migrated dominantly downward to Late Jurassic sandy reservoir rocks. Upward migration is restricted by dense shale and carbonate successions. Large accumulations of gas have been found in the basin, rather than oil. It seems that the amount of gases was significantly increased by secondary cracking of the oil in reservoir formations in deep and hot conditions.
Modeling Physiological Events in 2D vs. 3D Cell Culture.
Duval, Kayla; Grover, Hannah; Han, Li-Hsin; Mou, Yongchao; Pegoraro, Adrian F; Fredberg, Jeffery; Chen, Zi
2017-07-01
Cell culture has become an indispensable tool to help uncover fundamental biophysical and biomolecular mechanisms by which cells assemble into tissues and organs, how these tissues function, and how that function becomes disrupted in disease. Cell culture is now widely used in biomedical research, tissue engineering, regenerative medicine, and industrial practices. Although flat, two-dimensional (2D) cell culture has predominated, recent research has shifted toward culture using three-dimensional (3D) structures, and more realistic biochemical and biomechanical microenvironments. Nevertheless, in 3D cell culture, many challenges remain, including the tissue-tissue interface, the mechanical microenvironment, and the spatiotemporal distributions of oxygen, nutrients, and metabolic wastes. Here, we review 2D and 3D cell culture methods, discuss advantages and limitations of these techniques in modeling physiologically and pathologically relevant processes, and suggest directions for future research. Copyright © 2017 the American Physiological Society.
Nested 1D-2D approach for urban surface flood modeling
Murla, Damian; Willems, Patrick
2015-04-01
Floods in urban areas as a consequence of sewer capacity exceedance receive increased attention because of trends in urbanization (increased population density and impermeability of the surface) and climate change. Despite the strong recent developments in numerical modeling of water systems, urban surface flood modeling is still a major challenge. Whereas very advanced and accurate flood modeling systems are in place and operation by many river authorities in support of flood management along rivers, this is not yet the case in urban water management. Reasons include the small scale of the urban inundation processes, the need to have very high resolution topographical information available, and the huge computational demands. Urban drainage related inundation modeling requires a 1D full hydrodynamic model of the sewer network to be coupled with a 2D surface flood model. To reduce the computational times, 0D (flood cones), 1D/quasi-2D surface flood modeling approaches have been developed and applied in some case studies. In this research, a nested 1D/2D hydraulic model has been developed for an urban catchment at the city of Gent (Belgium), linking the underground sewer (minor system) with the overland surface (major system). For the overland surface flood modelling, comparison was made of 0D, 1D/quasi-2D and full 2D approaches. The approaches are advanced by considering nested 1D-2D approaches, including infiltration in the green city areas, and allowing the effects of surface storm water storage to be simulated. An optimal nested combination of three different mesh resolutions was identified; based on a compromise between precision and simulation time for further real-time flood forecasting, warning and control applications. Main streets as mesh zones together with buildings as void regions constitute one of these mesh resolution (3.75m2 - 15m2); they have been included since they channel most of the flood water from the manholes and they improve the accuracy of
Activated sludge models ASM1, ASM2, ASM2d and ASM3
DEFF Research Database (Denmark)
Henze, Mogens; Gujer, W.; Mino, T.
This book has been produced to give a total overview of the Activated Sludge Model (ASM) family at the start of 2000 and to give the reader easy access to the different models in their original versions. It thus presents ASM1, ASM2, ASM2d and ASM3 together for the first time.Modelling of activated......: Introduction, ASM 2, Typical Wastewater Characteristics and Kinetic and Stoichiometric Constants, Wastewater Characterization for Activated Sludge Processes, Calibration of the ASM 2, Model Limitations, Conclusion, Bibliography ASM 1: Introduction, Method of Model Presentation, Model Incorporating Carbon...... Oxidation Nitrification and Denitrification, Characterization of Wastewater and Estimation of Parameter Values, Typical Parameter Ranges, Default Values, and Effects of Environmental Factors, Assumptions, Restrictions and Constraints, Implementation of the Activated Sludge Model...
Magnetic properties of 2D nano-islands I: Ising spin model
Energy Technology Data Exchange (ETDEWEB)
Khater, A. [Laboratoire de Physique de L' Etat Condense, UMR 6087, Universite du Maine, 72085 Le Mans (France); Abou Ghantous, M., E-mail: michel.aboughantous@qatar.tamu.edu [Department of Physics, Texas A and M University at Qatar, Education City, PO Box 23874, Doha (Qatar)
2011-11-15
An Ising spin effective field theory (EFT) is developed as a framework for a detailed analysis of the magnetic properties of two-dimensional (2D) nano-islands on a nonmagnetic substrate with an out of plane magnetization. The Hamiltonian with nearest neighbor exchange interactions and single-atom magnetic anisotropy defines the ground state. The calculation yields the single site spin correlations, the magnetizations, and the isothermal susceptibilities for the core and periphery domains, and the island core phase diagrams. The choice of a spin S=1 for the atoms permits the analysis of the effects of spin fluctuations via the single site spin correlations. In particular we investigate the effects due to the different anisotropies and reduced dimensionalities for the core and periphery domains. The present model calculations are developed for different 2D nano-islands lattices. Detailed theoretical results are presented for the square and hexagonal lattices, with numerical applications for the 2D Co nano-islands on Pt. The derived transition temperature for the hexagonal lattice nano-islands is in good agreement with the experimental data for Co nano-islands on Pt. Though both the core and the periphery domains have the same order-disorder transition temperature, the magnetization of each domain attains this transition differently. The temperature behavior of the spin correlations is also fundamentally different for the periphery and core sites, which entails distinctly different isothermal susceptibilities, and yields statistically averaged nano-islands susceptibilities that do not correspond to a second order phase transition. The experimental susceptibility results for 2D Co nano-islands on Pt can be interpreted within our EFT Ising model without reference to a transition from a blocking state of the particle to a superparamagnetic behavior. The results for the different lattices are formally comparable, and demonstrate the robustness and general character of the
Uncertainties in modelling Mt. Pinatubo eruption with 2-D AER model and CCM SOCOL
Kenzelmann, P.; Weisenstein, D.; Peter, T.; Luo, B. P.; Rozanov, E.; Fueglistaler, S.; Thomason, L. W.
2009-04-01
Large volcanic eruptions may introduce a strong forcing on climate. They challenge the skills of climate models. In addition to the short time attenuation of solar light by ashes the formation of stratospheric sulphate aerosols, due to volcanic sulphur dioxide injection into the lower stratosphere, may lead to a significant enhancement of the global albedo. The sulphate aerosols have a residence time of about 2 years. As a consequence of the enhanced sulphate aerosol concentration both the stratospheric chemistry and dynamics are strongly affected. Due to absorption of longwave and near infrared radiation the temperature in the lower stratosphere increases. So far chemistry climate models overestimate this warming [Eyring et al. 2006]. We present an extensive validation of extinction measurements and model runs of the eruption of Mt. Pinatubo in 1991. Even if Mt. Pinatubo eruption has been the best quantified volcanic eruption of this magnitude, the measurements show considerable uncertainties. For instance the total amount of sulphur emitted to the stratosphere ranges from 5-12 Mt sulphur [e.g. Guo et al. 2004, McCormick, 1992]. The largest uncertainties are in the specification of the main aerosol cloud. SAGE II, for instance, could not measure the peak of the aerosol extinction for about 1.5 years, because optical termination was reached. The gap-filling of the SAGE II [Thomason and Peter, 2006] using lidar measurements underestimates the total extinctions in the tropics for the first half year after the eruption by 30% compared to AVHRR [Rusell et. al 1992]. The same applies to the optical dataset described by Stenchikov et al. [1998]. We compare these extinction data derived from measurements with extinctions derived from AER 2D aerosol model calculations [Weisenstein et al., 2007]. Full microphysical calculations with injections of 14, 17, 20 and 26 Mt SO2 in the lower stratosphere were performed. The optical aerosol properties derived from SAGE II
Calculation of the band structure of 2d conducting polymers using the network model
International Nuclear Information System (INIS)
Sabra, M. K.; Suman, H.
2007-01-01
the network model has been used to calculate the band structure the gap energy and Fermi level of conducting polymers in two dimensions. For this purpose, a geometrical classification of possible polymer chains configurations in two dimensions has been introduced leading to a classification of the unit cells based on the number of bonds in them. The model has been applied to graphite in 2D, represented by a three bonds unit cell, and, as a new case, the anti-parallel Polyacetylene chains (PA) in two dimensions, represented by a unit cell with four bons. The results are in good agreement with the first principles calculations. (author)
Hydrodynamic model for 2D degenerate free-electron gas for arbitrary frequencies
Castillo, M D; Cocoletzi, G H
2003-01-01
Following Halevi's procedure for 3D degenerate free-electron gas (3D-DEG), we investigate the response function in the hydrodynamic model (HM) for 2D-DEG confined in low dimensional systems when collisions are included. For small wave vectors we found from the two- dimensional Boltzmann-Mermin model a useful expression for the HM complex stiffness parameter of the nonlocal dielectric function beta, which is beta = [((3 omega/ 4) + i(v/ 2)) / (w + iv)]v sub F , where omega and v are the circular and collisional frequencies and v sub F is the Fermi velocity. (Author)
Canonical vs. micro-canonical sampling methods in a 2D Ising model
International Nuclear Information System (INIS)
Kepner, J.
1990-12-01
Canonical and micro-canonical Monte Carlo algorithms were implemented on a 2D Ising model. Expressions for the internal energy, U, inverse temperature, Z, and specific heat, C, are given. These quantities were calculated over a range of temperature, lattice sizes, and time steps. Both algorithms accurately simulate the Ising model. To obtain greater than three decimal accuracy from the micro-canonical method requires that the more complicated expression for Z be used. The overall difference between the algorithms is small. The physics of the problem under study should be the deciding factor in determining which algorithm to use. 13 refs., 6 figs., 2 tabs
Brane brick models, toric Calabi-Yau 4-folds and 2d (0,2) quivers
Energy Technology Data Exchange (ETDEWEB)
Franco, Sebastián [Physics Department, The City College of the CUNY, 160 Convent Avenue, New York, NY 10031 (United States); The Graduate School and University Center, The City University of New York,365 Fifth Avenue, New York NY 10016 (United States); Lee, Sangmin [Center for Theoretical Physics, Seoul National University,Seoul 08826 (Korea, Republic of); Department of Physics and Astronomy, Seoul National University,Seoul 08826 (Korea, Republic of); College of Liberal Studies, Seoul National University,Seoul 08826 (Korea, Republic of); School of Natural Sciences, Institute for Advanced Study,Princeton, NJ 08540 (United States); Seong, Rak-Kyeong [School of Physics, Korea Institute for Advanced Study,Seoul 02455 (Korea, Republic of)
2016-02-08
We introduce brane brick models, a novel type of Type IIA brane configurations consisting of D4-branes ending on an NS5-brane. Brane brick models are T-dual to D1-branes over singular toric Calabi-Yau 4-folds. They fully encode the infinite class of 2d (generically) N=(0,2) gauge theories on the worldvolume of the D1-branes and streamline their connection to the probed geometries. For this purpose, we also introduce new combinatorial procedures for deriving the Calabi-Yau associated to a given gauge theory and vice versa.
Validation and uncertainty analysis of a pre-treatment 2D dose prediction model
Baeza, Jose A.; Wolfs, Cecile J. A.; Nijsten, Sebastiaan M. J. J. G.; Verhaegen, Frank
2018-02-01
Independent verification of complex treatment delivery with megavolt photon beam radiotherapy (RT) has been effectively used to detect and prevent errors. This work presents the validation and uncertainty analysis of a model that predicts 2D portal dose images (PDIs) without a patient or phantom in the beam. The prediction model is based on an exponential point dose model with separable primary and secondary photon fluence components. The model includes a scatter kernel, off-axis ratio map, transmission values and penumbra kernels for beam-delimiting components. These parameters were derived through a model fitting procedure supplied with point dose and dose profile measurements of radiation fields. The model was validated against a treatment planning system (TPS; Eclipse) and radiochromic film measurements for complex clinical scenarios, including volumetric modulated arc therapy (VMAT). Confidence limits on fitted model parameters were calculated based on simulated measurements. A sensitivity analysis was performed to evaluate the effect of the parameter uncertainties on the model output. For the maximum uncertainty, the maximum deviating measurement sets were propagated through the fitting procedure and the model. The overall uncertainty was assessed using all simulated measurements. The validation of the prediction model against the TPS and the film showed a good agreement, with on average 90.8% and 90.5% of pixels passing a (2%,2 mm) global gamma analysis respectively, with a low dose threshold of 10%. The maximum and overall uncertainty of the model is dependent on the type of clinical plan used as input. The results can be used to study the robustness of the model. A model for predicting accurate 2D pre-treatment PDIs in complex RT scenarios can be used clinically and its uncertainties can be taken into account.
Quantum-critical scaling of fidelity in 2D pairing models
International Nuclear Information System (INIS)
Adamski, Mariusz; Jȩdrzejewski, Janusz; Krokhmalskii, Taras
2017-01-01
The laws of quantum-critical scaling theory of quantum fidelity, dependent on the underlying system dimensionality D, have so far been verified in exactly solvable 1D models, belonging to or equivalent to interacting, quadratic (quasifree), spinless or spinfull, lattice-fermion models. The obtained results are so appealing that in quest for correlation lengths and associated universal critical indices ν, which characterize the divergence of correlation lengths on approaching critical points, one might be inclined to substitute the hard task of determining an asymptotic behavior at large distances of a two-point correlation function by an easier one, of determining the quantum-critical scaling of the quantum fidelity. However, the role of system's dimensionality has been left as an open problem. Our aim in this paper is to fill up this gap, at least partially, by verifying the laws of quantum-critical scaling theory of quantum fidelity in a 2D case. To this end, we study correlation functions and quantum fidelity of 2D exactly solvable models, which are interacting, quasifree, spinfull, lattice-fermion models. The considered 2D models exhibit new, as compared with 1D ones, features: at a given quantum-critical point there exists a multitude of correlation lengths and multiple universal critical indices ν, since these quantities depend on spatial directions, moreover, the indices ν may assume larger values. These facts follow from the obtained by us analytical asymptotic formulae for two-point correlation functions. In such new circumstances we discuss the behavior of quantum fidelity from the perspective of quantum-critical scaling theory. In particular, we are interested in finding out to what extent the quantum fidelity approach may be an alternative to the correlation-function approach in studies of quantum-critical points beyond 1D.
2D-3D Registration of CT Vertebra Volume to Fluoroscopy Projection: A Calibration Model Assessment
Directory of Open Access Journals (Sweden)
P. Bifulco
2010-01-01
Full Text Available This study extends a previous research concerning intervertebral motion registration by means of 2D dynamic fluoroscopy to obtain a more comprehensive 3D description of vertebral kinematics. The problem of estimating the 3D rigid pose of a CT volume of a vertebra from its 2D X-ray fluoroscopy projection is addressed. 2D-3D registration is obtained maximising a measure of similarity between Digitally Reconstructed Radiographs (obtained from the CT volume and real fluoroscopic projection. X-ray energy correction was performed. To assess the method a calibration model was realised a sheep dry vertebra was rigidly fixed to a frame of reference including metallic markers. Accurate measurement of 3D orientation was obtained via single-camera calibration of the markers and held as true 3D vertebra position; then, vertebra 3D pose was estimated and results compared. Error analysis revealed accuracy of the order of 0.1 degree for the rotation angles of about 1 mm for displacements parallel to the fluoroscopic plane, and of order of 10 mm for the orthogonal displacement.
3D vs 2D laparoscopic systems: Development of a performance quantitative validation model.
Ghedi, Andrea; Donarini, Erica; Lamera, Roberta; Sgroi, Giovanni; Turati, Luca; Ercole, Cesare
2015-01-01
The new technology ensures 3D laparoscopic vision by adding depth to the traditional two dimensions. This realistic vision gives the surgeon the feeling of operating in real space. Hospital of Treviglio-Caravaggio isn't an university or scientific institution; in 2014 a new 3D laparoscopic technology was acquired therefore it led to evaluation of the of the appropriateness in term of patient outcome and safety. The project aims at achieving the development of a quantitative validation model that would ensure low cost and a reliable measure of the performance of 3D technology versus 2D mode. In addition, it aims at demonstrating how new technologies, such as open source hardware and software and 3D printing, could help research with no significant cost increase. For these reasons, in order to define criteria of appropriateness in the use of 3D technologies, it was decided to perform a study to technically validate the use of the best technology in terms of effectiveness, efficiency and safety in the use of a system between laparoscopic vision in 3D and the traditional 2D. 30 surgeons were enrolled in order to perform an exercise through the use of laparoscopic forceps inside a trainer. The exercise consisted of having surgeons with different level of seniority, grouped by type of specialization (eg. surgery, urology, gynecology), exercising videolaparoscopy with two technologies (2D and 3D) through the use of a anthropometric phantom. The target assigned to the surgeon was that to pass "needle and thread" without touching the metal part in the shortest time possible. The rings selected for the exercise had each a coefficient of difficulty determined by depth, diameter, angle from the positioning and from the point of view. The analysis of the data collected from the above exercise has mathematically confirmed that the 3D technique ensures a learning curve lower in novice and greater accuracy in the performance of the task with respect to 2D.
Kolkoori, S. R.; Rahaman, M.-U.; Chinta, P. K.; Kreutzbruck, M.; Prager, J.
2012-05-01
Ultrasonic investigation of inhomogeneous anisotropic materials such as austenitic welds is complicated because its columnar grain structure leads to curved energy paths, beam splitting and asymmetrical beam profiles. A ray tracing model has potential advantage in analyzing the ultrasonic sound field propagation and there with optimizing the inspection parameters. In this contribution we present a 2D ray tracing model to predict energy ray paths, ray amplitudes and travel times for the three wave modes quasi longitudinal, quasi shear vertical, and shear horizontal waves in austenitic weld materials. Inhomogenity in the austenitic weld material is represented by discretizing the inhomogeneous region into several homogeneous layers. At each interface between the layers the reflection and transmission problem is computed and yields energy direction, amplitude and energy coefficients. The ray amplitudes are computed accurately by taking into account directivity, divergence and density of rays, phase relations as well as transmission coefficients. Ultrasonic sound fields obtained from the ray tracing model are compared quantitatively with the 2D Elastodynamic Finite Integration Technique (EFIT). The excellent agreement between both models confirms the validity of the presented ray tracing results. Experiments are conducted on austenitic weld samples with longitudinal beam transducer as transmitting probe and amplitudes at the rear surface are scanned by means of electrodynamical probes. Finally, the ray tracing model results are also validated through the experiments.
A 2D-View Depth Image- and CNN-Based 3D Model Identification Method
Directory of Open Access Journals (Sweden)
Yiyu Hong
2017-09-01
Full Text Available With the rapid development of three-dimensional (3D technology and an increase in the number of available models, issues with copyright protection of 3D models are inevitable. In this paper, we propose a 2D-view depth image- and convolutional neural network (CNN-based 3D model identification method. To identify a 3D model, we first need an adequate number of the modified versions that could be made by copyright infringers. Then, they can be represented by a number of 2D-view depth images that are captured from evenly distributed vertices on a regular convex polyhedron. Finally, a CNN is trained by these depth images to acquire the capability of identifying the 3D model. The experiment carried out with the dataset of Shape Retrieval Contest 2015 (SHREC’15: Non-Rigid 3D Shape Retrieval shows the practicability of our method, which yields 93.5% accuracy. The effectiveness of the proposed method is demonstrated via evaluation in the latest standard benchmark SHREC’17 Deformable Shape Retrieval with Missing Parts. It clearly shows superior or comparable performance to state-of-the-art methods, shown by the fact that it is in the top three of the 11 participating methods (without counting different runs.
2D lattice model of a lipid bilayer: Microscopic derivation and thermodynamic exploration
Hakobyan, Davit; Heuer, Andreas
2017-02-01
Based on all-atom Molecular Dynamics (MD) simulations of a lipid bilayer we present a systematic mapping on a 2D lattice model. Keeping the lipid type and the chain order parameter as key variables we derive a free energy functional, containing the enthalpic interaction of adjacent lipids as well as the tail entropy. The functional form of both functions is explicitly determined for saturated and polyunsaturated lipids. By studying the lattice model via Monte Carlo simulations it is possible to reproduce the temperature dependence of the distribution of order parameters of the pure lipids, including the prediction of the gel transition. Furthermore, application to a mixture of saturated and polyunsaturated lipids yields the correct phase separation behavior at lower temperatures with a simulation time reduced by approximately 7 orders of magnitude as compared to the corresponding MD simulations. Even the time-dependence of the de-mixing is reproduced on a semi-quantitative level. Due to the generality of the approach we envisage a large number of further applications, ranging from modeling larger sets of lipids, sterols, and solvent proteins to predicting nucleation barriers for the melting of lipids. Particularly, from the properties of the 2D lattice model one can directly read off the enthalpy and entropy change of the 1,2-dipalmitoyl-sn-glycero-3-phosphocholine gel-to-liquid transition in excellent agreement with experimental and MD results.
2d forward modelling of marine CSEM survey geometry for seabed logging
International Nuclear Information System (INIS)
Hussain, N.; Noh, M.; Yahya, N.B.
2011-01-01
Hydrocarbon reserve exploration in deep water is done by geophysical surveys. Previously seismic geophysical surveys were explicitly used but it has indistinct results for both water and hydrocarbon saturated reservoir. Recent development for the detection of hydrocarbon reservoir in deeper water is Marine Controlled Source Electromagnetic (MCSEM) geophysical survey. MCSEM is sensitive to electrical conductivity of rocks by which it can differentiate between hydrocarbon reservoir and water saturated reservoir. MCSEM survey geometry put vital role and may causes for anomalies in synthetic data. Consequentially MCSEM is sensitive to survey geometry (e.g. source dipping, rotation and speed, receivers' orientation etc) which causes anomalies. The interpretation for delineating subsurface structure from survey data need to well understand the effects of survey geometry anomalies. Forward modelling is an alternative rather real time survey to study the aforementioned anomalies. In this paper finite difference method (FDM) is implemented for 2D forward modelling in the sense of qualitative understanding to how induced Electromagnetic (EM) signal changes its overall pattern while interact with physical earth properties. A stratified earth structure is developed and modelled in MatLabTM software to study the behaviour of EM field with physical earth properties. Obtained results of 2D geological models are also discussed in this paper. (author)
Rotating 2d point source plume models with application to Deepwater Horizon
Fabregat, A.; Deremble, B.; Wienders, N.; Stroman, A.; Poje, A.; Özgökmen, T. M.; Dewar, W. K.
2017-11-01
The 2010 Deepwater Horizon (DwH) accident in the Gulf of Mexico has renewed oceanographic interest in point source buoyant convection. The present paper applies modern numerical techniques to study this problem, focussing specifically on the DwH event. The gas/oil/seawater nature of the problem requires a 'multiphase' approach, which is relatively unfamiliar in physical oceanography, although applications are becoming more common. The model is cast in an Eulerian framework and includes feedbacks between the convection and the environment, unlike past oil/gas plume simulations that adopt a semi-passive, Lagrangian approach. Fully three dimensional (3d) simulations are too computationally demanding for practical multi-day use, so a two-dimensional (2d) radially symmetric model is developed from the equations and calibrated to the 3d results. Both the 2d and 3d solutions show the somewhat unexpected result that oil/bubble plumes modelled after the DwH event are strongly affected by rotation and exert a considerable dynamic feedback on the ambient. These effects are not typically included in classical oil/gas plume models.
Comparative analysis of 2D and 3D model of a PEMFC in COMSOL
Lakshmi, R. Bakiya; Harikrishnan, N. P.; Juliet, A. Vimala
2017-10-01
In this article, 2D and 3D model of a PEMFC has been simulated in order to study their performance when subjected to similar operating conditions. The comparison reveals interesting phenomena of performance enhancement of the fuel cell. Design of fuel cell channel and stationary studies were done in COMSOL. Variations in current density and electrolyte potential from simulation results were observed when operated at a temperature of 120 °C. The electrolyte potential was found to have increased from 1 to 2.5 V and the surface pressure due to fluid flow was found to have increased from 3 to 9.58 Pa.
Entanglement entropy through conformal interfaces in the 2D Ising model
Brehm, Enrico M
2015-01-01
We consider the entanglement entropy for the 2D Ising model at the conformal fixed point in the presence of interfaces. More precisely, we investigate the situation where the two subsystems are separated by a defect line that preserves conformal invariance. Using the replica trick, we compute the entanglement entropy between the two subsystems. We observe that the entropy, just like in the case without defects, shows a logarithmic scaling behavior with respect to the size of the system. Here, the prefactor of the logarithm depends on the strength of the defect encoded in the transmission coefficient. We also commend on the supersymmetric case.
Static properties of 2D spin-ice as a sixteen-vertex model
International Nuclear Information System (INIS)
Foini, Laura; Levis, Demian; Cugliandolo, Leticia F; Tarzia, Marco
2013-01-01
We present a thorough study of the static properties of 2D models of spin-ice type on the square lattice or, in other words, the sixteen-vertex model. We use extensive Monte Carlo simulations to determine the phase diagram and critical properties of the finite-dimensional system. We put forward a suitable mean-field approximation, by defining the model on carefully chosen trees. We employ the cavity (Bethe–Peierls) method to derive self-consistent equations, the fixed points of which yield the equilibrium properties of the model on the tree-like graph. We compare mean-field and finite-dimensional results. We discuss our findings in the context of experiments in artificial two-dimensional spin-ice. (paper)
Stochastic dynamics of phase singularities under ventricular fibrillation in 2D Beeler-Reuter model
Directory of Open Access Journals (Sweden)
Akio Suzuki
2011-09-01
Full Text Available The dynamics of ventricular fibrillation (VF has been studied extensively, and the initiation mechanism of VF has been elucidated to some extent. However, the stochastic dynamical nature of sustained VF remains unclear so far due to the complexity of high dimensional chaos in a heterogeneous system. In this paper, various statistical mechanical properties of sustained VF are studied numerically in 2D Beeler-Reuter-Drouhard-Roberge (BRDR model with normal and modified ionic current conductance. The nature of sustained VF is analyzed by measuring various fluctuations of spatial phase singularity (PS such as velocity, lifetime, the rates of birth and death. It is found that the probability density function (pdf for lifetime of PSs is independent of system size. It is also found that the hyper-Gamma distribution serves as a universal pdf for the counting number of PSs for various system sizes and various parameters of our model tissue under VF. Further, it is demonstrated that the nonlinear Langevin equation associated with a hyper-Gamma process can mimic the pdf and temporal variation of the number of PSs in the 2D BRDR model.
Mechanical Modelling of Pultrusion Process: 2D and 3D Numerical Approaches
DEFF Research Database (Denmark)
Baran, Ismet; Hattel, Jesper Henri; Akkerman, Remko
2015-01-01
The process induced variations such as residual stresses and distortions are a critical issue in pultrusion, since they affect the structural behavior as well as the mechanical properties and geometrical precision of the final product. In order to capture and investigate these variations, a mecha......The process induced variations such as residual stresses and distortions are a critical issue in pultrusion, since they affect the structural behavior as well as the mechanical properties and geometrical precision of the final product. In order to capture and investigate these variations......, a mechanical analysis should be performed. In the present work, the two dimensional (2D) quasi-static plane strain mechanical model for the pultrusion of a thick square profile developed by the authors is further improved using generalized plane strain elements. In addition to that, a more advanced 3D thermo-chemical-mechanical...... analysis is carried out using 3D quadratic elements which is a novel application for the numerical modelling of the pultrusion process. It is found that the 2D mechanical models give relatively reasonable and accurate stress and displacement evolutions in the transverse direction as compared to the 3D...
Self-Organization in 2D Traffic Flow Model with Jam-Avoiding Drive
Nagatani, Takashi
1995-04-01
A stochastic cellular automaton (CA) model is presented to investigate the traffic jam by self-organization in the two-dimensional (2D) traffic flow. The CA model is the extended version of the 2D asymmetric exclusion model to take into account jam-avoiding drive. Each site contains either a car moving to the up, a car moving to the right, or is empty. A up car can shift right with probability p ja if it is blocked ahead by other cars. It is shown that the three phases (the low-density phase, the intermediate-density phase and the high-density phase) appear in the traffic flow. The intermediate-density phase is characterized by the right moving of up cars. The jamming transition to the high-density jamming phase occurs with higher density of cars than that without jam-avoiding drive. The jamming transition point p 2c increases with the shifting probability p ja. In the deterministic limit of p ja=1, it is found that a new jamming transition occurs from the low-density synchronized-shifting phase to the high-density moving phase with increasing density of cars. In the synchronized-shifting phase, all up cars do not move to the up but shift to the right by synchronizing with the move of right cars. We show that the jam-avoiding drive has an important effect on the dynamical jamming transition.
Qu, Qiang; Qu, Jian; Han, Lu; Zhan, Min; Wu, Lan-xiang; Zhang, Yi-wen; Zhang, Wei; Zhou, Hong-hao
2014-01-01
Aim: Herbal products have been widely used, and the safety of herb-drug interactions has aroused intensive concerns. This study aimed to investigate the effects of phytochemicals on the catalytic activities of human CYP2D6*1 and CYP2D6*10 in vitro. Methods: HepG2 cells were stably transfected with CYP2D6*1 and CYP2D6*10 expression vectors. The metabolic kinetics of the enzymes was studied using HPLC and fluorimetry. Results: HepG2-CYP2D6*1 and HepG2-CYP2D6*10 cell lines were successfully constructed. Among the 63 phytochemicals screened, 6 compounds, including coptisine sulfate, bilobalide, schizandrin B, luteolin, schizandrin A and puerarin, at 100 μmol/L inhibited CYP2D6*1- and CYP2D6*10-mediated O-demethylation of a coumarin compound AMMC by more than 50%. Furthermore, the inhibition by these compounds was dose-dependent. Eadie-Hofstee plots demonstrated that these compounds competitively inhibited CYP2D6*1 and CYP2D6*10. However, their Ki values for CYP2D6*1 and CYP2D6*10 were very close, suggesting that genotype-dependent herb-drug inhibition was similar between the two variants. Conclusion: Six phytochemicals inhibit CYP2D6*1 and CYP2D6*10-mediated catalytic activities in a dose-dependent manner in vitro. Thus herbal products containing these phytochemicals may inhibit the in vivo metabolism of co-administered drugs whose primary route of elimination is CYP2D6. PMID:24786236
A comparative 2D modeling of debris-flow propagation and outcomes for end-users
Bettella, F.; Bertoldi, G.; Pozza, E.; McArdell, B. W.; D'Agostino, V.
2012-04-01
In Alpine regions gravity-driven natural hazards, in particular debris flows, endanger settlements and human life. Mitigation strategies based on hazard maps are necessary tools for land planning. These maps can be made more precise by using numerical models to forecasting the inundated areas after a careful setting of those 'key parameters' (K-P) which directly affect the flow motion and its interaction with the ground surface. Several physically based 2D models are available for practitioners and governmental agencies, but the selection criteria of model type and of the related K-P remain flexible and partly subjective. This remark has driven us to investigate how different models simulate different types of debris flows (from granular to muddy debris flows, going through intermediate types), in particular when the flow is influenced by the presence of deposition basins. Two commercial 2D physical models (RAMMS and FLO-2D) have been tested for five well-documented debris flows events from five Italian catchments were different geology and flow dynamics are observed: 1) a viscous debris flow occurred in 2009 in a catchment with a metamorphic geology (Gadria torrent, Bolzano Province); 2) the 2009 granular debris flow in an granitic geological setting (Rio Dosson, Trento Province); 3-4) two events occurred in the 'rio Val del Lago' and 'rio Molinara' (Trento Province) in 2010 where porphyritic lithology prevails (intermediate granular debris flow); 5) the Rotolon torrent (Vicenza Province) 2009 debris flow containing sedimentary rocks enclosed in an abundant clay-rich matrix (intermediate viscous case). Event volumes range from 5.000 to 50.000 cubic meters. The Gadria, Rotolon and Val del Lago events are also influenced by artificial retention basins. Case study simulations allowed delineation of some practical end-user suggestions and good practices in order to guide the model choice and the K-P setting, particularly related to different flow dynamics. The
Kinetic parameter estimation in N. europaea biofilms using a 2-D reactive transport model.
Lauchnor, Ellen G; Semprini, Lewis; Wood, Brian D
2015-06-01
Biofilms of the ammonia oxidizing bacterium Nitrosomonas europaea were cultivated to study microbial processes associated with ammonia oxidation in pure culture. We explored the hypothesis that the kinetic parameters of ammonia oxidation in N. europaea biofilms were in the range of those determined with batch suspended cells. Oxygen and pH microelectrodes were used to measure dissolved oxygen (DO) concentrations and pH above and inside biofilms and reactive transport modeling was performed to simulate the measured DO and pH profiles. A two dimensional (2-D) model was used to simulate advection parallel to the biofilm surface and diffusion through the overlying fluid while reaction and diffusion were simulated in the biofilm. Three experimental studies of microsensor measurements were performed with biofilms: i) NH3 concentrations near the Ksn value of 40 μM determined in suspended cell tests ii) Limited buffering capacity which resulted in a pH gradient within the biofilms and iii) NH3 concentrations well below the Ksn value. Very good fits to the DO concentration profiles both in the fluid above and in the biofilms were achieved using the 2-D model. The modeling study revealed that the half-saturation coefficient for NH3 in N. europaea biofilms was close to the value measured in suspended cells. However, the third study of biofilms with low availability of NH3 deviated from the model prediction. The model also predicted shifts in the DO profiles and the gradient in pH that resulted for the case of limited buffering capacity. The results illustrate the importance of incorporating both key transport and chemical processes in a biofilm reactive transport model. © 2014 Wiley Periodicals, Inc.
Interchange turbulence model for the edge plasma in SOLEDGE2D-EIRENE
Energy Technology Data Exchange (ETDEWEB)
Bufferand, H.; Marandet, Y. [Aix-Marseille Universite, CNRS, PIIM, Marseille (France); Ciraolo, G.; Ghendrih, P.; Bucalossi, J.; Fedorczak, N.; Gunn, J.; Tamain, P. [CEA, IRFM, Saint-Paul-Lez-Durance (France); Colin, C.; Galassi, D.; Leybros, R.; Serre, E. [Aix-Marseille Universite, CNRS, M2P2, Marseille (France)
2016-08-15
Cross-field transport in edge tokamak plasmas is known to be dominated by turbulent transport. A dedicated effort has been made to simulate this turbulent transport from first principle models but the numerical cost to run these simulations on the ITER scale remains prohibitive. Edge plasma transport study relies mostly nowadays on so-called transport codes where the turbulent transport is taken into account using effective ad-hoc diffusion coefficients. In this contribution, we propose to introduce a transport equation for the turbulence intensity in SOLEDGE2D-EIRENE to describe the interchange turbulence properties. Going beyond the empirical diffusive model, this system automatically generates profiles for the turbulent transport and hence reduces the number of degrees of freedom for edge plasma transport codes. We draw inspiration from the k-epsilon model widely used in the neutral fluid community. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Observation of spatial charge and spin correlations in the 2D Fermi-Hubbard model.
Cheuk, Lawrence W; Nichols, Matthew A; Lawrence, Katherine R; Okan, Melih; Zhang, Hao; Khatami, Ehsan; Trivedi, Nandini; Paiva, Thereza; Rigol, Marcos; Zwierlein, Martin W
2016-09-16
Strong electron correlations lie at the origin of high-temperature superconductivity. Its essence is believed to be captured by the Fermi-Hubbard model of repulsively interacting fermions on a lattice. Here we report on the site-resolved observation of charge and spin correlations in the two-dimensional (2D) Fermi-Hubbard model realized with ultracold atoms. Antiferromagnetic spin correlations are maximal at half-filling and weaken monotonically upon doping. At large doping, nearest-neighbor correlations between singly charged sites are negative, revealing the formation of a correlation hole, the suppressed probability of finding two fermions near each other. As the doping is reduced, the correlations become positive, signaling strong bunching of doublons and holes, in agreement with numerical calculations. The dynamics of the doublon-hole correlations should play an important role for transport in the Fermi-Hubbard model. Copyright © 2016, American Association for the Advancement of Science.
Quasi 2D hydrodynamic modelling of the flooded hinterland due to dyke breaching on the Elbe River
Directory of Open Access Journals (Sweden)
S. Huang
2007-01-01
Full Text Available In flood modeling, many 1D and 2D combination and 2D models are used to simulate diversion of water from rivers through dyke breaches into the hinterland for extreme flood events. However, these models are too demanding in data requirements and computational resources which is an important consideration when uncertainty analysis using Monte Carlo techniques is used to complement the modeling exercise. The goal of this paper is to show the development of a quasi-2D modeling approach, which still calculates the dynamic wave in 1D but the discretisation of the computational units are in 2D, allowing a better spatial representation of the flow in the hinterland due to dyke breaching without a large additional expenditure on data pre-processing and computational time. A 2D representation of the flow and velocity fields is required to model sediment and micro-pollutant transport. The model DYNHYD (1D hydrodynamics from the WASP5 modeling package was used as a basis for the simulations. The model was extended to incorporate the quasi-2D approach and a Monte-Carlo Analysis was used to conduct a flood sensitivity analysis to determine the sensitivity of parameters and boundary conditions to the resulting water flow. An extreme flood event on the Elbe River, Germany, with a possible dyke breach area was used as a test case. The results show a good similarity with those obtained from another 1D/2D modeling study.
Be2D: A model to understand the distribution of meteoric 10Be in soilscapes
Campforts, Benjamin; Vanacker, Veerle; Vanderborght, Jan; Govers, Gerard
2016-04-01
Cosmogenic nuclides have revolutionised our understanding of earth surface process rates. They have become one of the standard tools to quantify soil production by weathering, soil redistribution and erosion. Especially Beryllium-10 has gained much attention due to its long half-live and propensity to be relatively conservative in the landscape. The latter makes 10Be an excellent tool to assess denudation rates over the last 1000 to 100 × 103 years, bridging the anthropogenic and geological time scale. Nevertheless, the mobility of meteoric 10Be in soil systems makes translation of meteoric 10Be inventories into erosion and deposition rates difficult. Here we present a coupled soil hillslope model, Be2D, that is applied to synthetic and real topography to address the following three research questions. (i) What is the influence of vertical meteoric Be10 mobility, caused by chemical mobility, clay translocation and bioturbation, on its lateral redistribution over the soilscape, (ii) How does vertical mobility influence erosion rates and soil residence times inferred from meteoric 10Be inventories and (iii) To what extent can a tracer with a half-life of 1.36 Myr be used to distinguish between natural and human-disturbed soil redistribution rates? The model architecture of Be2D is designed to answer these research questions. Be2D is a dynamic model including physical processes such as soil formation, physical weathering, clay migration, bioturbation, creep, overland flow and tillage erosion. Pathways of meteoric 10Be mobility are simulated using a two step approach which is updated each timestep. First, advective and diffusive mobility of meteoric 10Be is simulated within the soil profile and second, lateral redistribution because of lateral soil fluxes is calculated. The performance and functionality of the model is demonstrated through a number of synthetic and real model runs using existing datasets of meteoric 10Be from case-studies in southeastern US. Brute
A New Material Model for 2D FE Analysis of Adhesively Bonded Composite Joints
Directory of Open Access Journals (Sweden)
Libin ZHAO
2014-12-01
Full Text Available Effective and convenient stress analysis techniques play important roles in the analysis and design of adhesively bonded composite joints. A new material model is presented at the level of composite ply according to the orthotropic elastic mechanics theory and plane strain assumption. The model proposed has the potential to reserve nature properties of laminates with ply-to-ply modeling. The equivalent engineering constants in the model are obtained only by the material properties of unidirectional composites. Based on commercial FE software ABAQUS, a 2D FE model of a single-lap adhesively bonded joint was established conveniently by using the new model without complex modeling process and much professional knowledge. Stress distributions in adhesive were compared with the numerical results by Tsai and Morton and interlaminar stresses between adhesive and adherents were compared with the results from a detailed 3D FE analysis. Good agreements in both cases verify the validity of the proposed model. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.5960
Short distance behaviour of correlators in the 2d Ising model in a magnetic field
Energy Technology Data Exchange (ETDEWEB)
Caselle, M. E-mail: caselle@to.infn.it; Grinza, P. E-mail: grinza@to.infn.it; Magnoli, N. E-mail: magnoli@ge.infn.it
2000-07-24
We study the <{sigma}{sigma}>, <{sigma}{epsilon}>, <{epsilon}{epsilon}> correlators in the 2d Ising model perturbed by a magnetic field. We compare the results of a set of high precision Monte Carlo simulations with the predictions of two different approximations: the Form Factor approach, based on the exact S-matrix description of the model, and a short distance perturbative expansion around the conformal point. Both methods give very good results, the first one performs better for distances larger than the correlation length, while the second one is more precise for distances smaller than the correlation length. In order to improve this agreement we extend the perturbative analysis to the second order in the derivatives of the OPE constants.
A local time stepping algorithm for GPU-accelerated 2D shallow water models
Dazzi, Susanna; Vacondio, Renato; Dal Palù, Alessandro; Mignosa, Paolo
2018-01-01
In the simulation of flooding events, mesh refinement is often required to capture local bathymetric features and/or to detail areas of interest; however, if an explicit finite volume scheme is adopted, the presence of small cells in the domain can restrict the allowable time step due to the stability condition, thus reducing the computational efficiency. With the aim of overcoming this problem, the paper proposes the application of a Local Time Stepping (LTS) strategy to a GPU-accelerated 2D shallow water numerical model able to handle non-uniform structured meshes. The algorithm is specifically designed to exploit the computational capability of GPUs, minimizing the overheads associated with the LTS implementation. The results of theoretical and field-scale test cases show that the LTS model guarantees appreciable reductions in the execution time compared to the traditional Global Time Stepping strategy, without compromising the solution accuracy.
Optimization of cell seeding in a 2D bio-scaffold system using computational models.
Ho, Nicholas; Chua, Matthew; Chui, Chee-Kong
2017-05-01
The cell expansion process is a crucial part of generating cells on a large-scale level in a bioreactor system. Hence, it is important to set operating conditions (e.g. initial cell seeding distribution, culture medium flow rate) to an optimal level. Often, the initial cell seeding distribution factor is neglected and/or overlooked in the design of a bioreactor using conventional seeding distribution methods. This paper proposes a novel seeding distribution method that aims to maximize cell growth and minimize production time/cost. The proposed method utilizes two computational models; the first model represents cell growth patterns whereas the second model determines optimal initial cell seeding positions for adherent cell expansions. Cell growth simulation from the first model demonstrates that the model can be a representation of various cell types with known probabilities. The second model involves a combination of combinatorial optimization, Monte Carlo and concepts of the first model, and is used to design a multi-layer 2D bio-scaffold system that increases cell production efficiency in bioreactor applications. Simulation results have shown that the recommended input configurations obtained from the proposed optimization method are the most optimal configurations. The results have also illustrated the effectiveness of the proposed optimization method. The potential of the proposed seeding distribution method as a useful tool to optimize the cell expansion process in modern bioreactor system applications is highlighted. Copyright © 2017 Elsevier Ltd. All rights reserved.
Destabilization of survival factor MEF2D mRNA by neurotoxin in models of Parkinson's disease.
Wang, Bao; Cai, Zhibiao; Lu, Fangfang; Li, Chen; Zhu, Xiaofei; Su, Linna; Gao, Guodong; Yang, Qian
2014-09-01
Progressive loss of dopaminergic (DA) neurons in the substantial nigra pars compacta (SNc) is an important pathological feature in Parkinson's disease (PD). Loss of transcription factor myocyte enhancer factor 2D (MEF2D), a key neuronal survival factor, has been shown to underlie the loss of DA neurons in SNc and the pathogenic process of PD. It is known that PD-associated neurotoxins reduce the level of MEF2D protein to trigger neuronal death. Although neurotoxins clearly destabilize MEF2D by post-translational mechanisms, it is not known whether regulation of MEF2D mRNA contributes to neurotoxin-induced decrease in MEF2D protein. In this work, we showed that MPP(+), the toxic metabolite of MPTP, caused a significant decrease in the half-life and total level of MEF2D mRNA in a DA neuronal cell line, SN4741 cells. Quantitative PCR analysis of the SNc DA neurons captured by immune-laser capture microdissection showed that exposure to MPTP led to a marked reduction in the level of MEF2D mRNA in SNc DA neurons compared to controls. Down-regulation of MEF2D mRNA alone reduced the viability of SN4741 cells and sensitized the cells to MPP(+)-induced toxicity. These results suggest that destabilization and reduction in MEF2D mRNA is in part responsible for neurotoxin-induced decrease in MEF2D protein and neuronal viability. Myocyte enhancer factor 2D (MEF2D) plays an important role in neuronal survival. How MEF2D mRNA is deregulated under toxic stress is unclear. We found that PD-associated neurotoxins destabilize MEF2D mRNA and reduce its level in vitro and in vivo. Reduction in MEF2D mRNA is sufficient to sensitize model cells to neurotoxin-induced toxicity, suggesting that destabilization of MEF2D mRNA is part of the mechanism by which neurotoxins trigger deregulation of neuronal survival. © 2014 International Society for Neurochemistry.
The combined effect of attraction and orientation zones in 2D flocking models
Iliass, Tarras; Cambui, Dorilson
2016-01-01
In nature, many animal groups, such as fish schools or bird flocks, clearly display structural order and appear to move as a single coherent entity. In order to understand the complex motion of these systems, we study the Vicsek model of self-propelled particles (SPP) which is an important tool to investigate the behavior of collective motion of live organisms. This model reproduces the biological behavior patterns in the two-dimensional (2D) space. Within the framework of this model, the particles move with the same absolute velocity and interact locally in the zone of orientation by trying to align their direction with that of the neighbors. In this paper, we model the collective movement of SPP using an agent-based model which follows biologically motivated behavioral rules, by adding a second region called the attraction zone, where each particles move towards each other avoiding being isolated. Our main goal is to present a detailed numerical study on the effect of the zone of attraction on the kinetic phase transition of our system. In our study, the consideration of this zone seems to play an important role in the cohesion. Consequently, in the directional orientation, the zone that we added forms the compact particle group. In our simulation, we show clearly that the model proposed here can produce two collective behavior patterns: torus and dynamic parallel group. Implications of these findings are discussed.
Time-dependent 2-D modeling of edge plasma transport with high intermittency due to blobs
International Nuclear Information System (INIS)
Pigarov, A. Yu.; Krasheninnikov, S. I.; Rognlien, T. D.
2012-01-01
The results on time-dependent 2-D fluid modeling of edge plasmas with non-diffusive intermittent transport across the magnetic field (termed cross-field) based on the novel macro-blob approach are presented. The capability of this approach to simulate the long temporal evolution (∼0.1 s) of the background plasma and simultaneously the fast spatiotemporal dynamics of blobs (∼10 −4 s) is demonstrated. An analysis of a periodic sequence of many macro-blobs (PSMB) is given showing that the resulting plasma attains a dynamic equilibrium. Plasma properties in the dynamic equilibrium are discussed. In PSMB modeling, the effect of macro-blob generation frequency on edge plasma parameters is studied. Comparison between PSMB modeling and experimental profile data is given. The calculations are performed for the same plasma discharge using two different models for anomalous cross-field transport: time-average convection and PSMB. Parametric analysis of edge plasma variation with transport coefficients in these models is presented. The capability of the models to accurately simulate enhanced transport due to blobs is compared. Impurity dynamics in edge plasma with macro-blobs is also studied showing strong impact of macro-blob on profiles of impurity charge states caused by enhanced outward transport of high-charge states and simultaneous inward transport of low-charge states towards the core. Macro-blobs cause enhancement of sputtering rates, increase radiation and impurity concentration in plasma, and change erosion/deposition patterns.
2017-01-12
Conference Paper with Briefing Charts 3. DATES COVERED (From - To) 17 November 2016 – 12 January 2017 4. TITLE AND SUBTITLE 2D and 3D Modeling ...98) Prescribed by ANSI Std. 239.18 2D and 3D Modeling Efforts in Fuel Film Cooling of Liquid Rocket Engines Kevin C. Brown∗, Edward B. Coy†, and...wide. As a consequence, the 3D simulations may better model the experimental setup used, but are perhaps not representative of the long circumferential
On new traveling wave solutions and conserved densities for the 2D Ricci flow model
Cimpoiasu, Rodica
2018-01-01
In this paper some travelling wave solutions and conservation laws for the 2D Ricci flow model in conformal gauge are investigated. A guideline able to classify the types of solutions according to the values of some parameters is provided by making use of two versions of the auxiliary equation method. The key feature of these approaches is to take a second order linear ordinary differential equation (ODE), respectively a first order nonlinear ODE with at most an eighth-degree nonlinear term as auxiliary equations. Conserved forms of the travelling wave equation for the Ricci flow are derived through three specific approaches, namely the variational approach, the Ibragimov method for nonlinear self-adjoint differential equations and the one based upon a relationship between conserved forms and their associated symmetries. The former two methods generated similar results, while the latter one has revealed new conserved densities.
Transition from static to kinetic friction: insights from a 2D model.
Trømborg, J; Scheibert, J; Amundsen, D S; Thøgersen, K; Malthe-Sørenssen, A
2011-08-12
We describe a 2D spring-block model for the transition from static to kinetic friction at an elastic-slider-rigid-substrate interface obeying a minimalistic friction law (Amontons-Coulomb). By using realistic boundary conditions, a number of previously unexplained experimental results on precursory microslip fronts are successfully reproduced. From the analysis of the interfacial stresses, we derive a prediction for the evolution of the precursor length as a function of the applied loads, as well as an approximate relationship between microscopic and macroscopic friction coefficients. We show that the stress buildup due to both elastic loading and microslip-related relaxations depends only weakly on the underlying shear crack propagation dynamics. Conversely, crack speed depends strongly on both the instantaneous stresses and the friction coefficients, through a nontrivial scaling parameter.
Zieliński, Tomasz G.
2017-11-01
The paper proposes and investigates computationally-efficient microstructure representations for sound absorbing fibrous media. Three-dimensional volume elements involving non-trivial periodic arrangements of straight fibres are examined as well as simple two-dimensional cells. It has been found that a simple 2D quasi-representative cell can provide similar predictions as a volume element which is in general much more geometrically accurate for typical fibrous materials. The multiscale modelling allowed to determine the effective speeds and damping of acoustic waves propagating in such media, which brings up a discussion on the correlation between the speed, penetration range and attenuation of sound waves. Original experiments on manufactured copper-wire samples are presented and the microstructure-based calculations of acoustic absorption are compared with the corresponding experimental results. In fact, the comparison suggested the microstructure modifications leading to representations with non-uniformly distributed fibres.
An application of the distributed hydrologic model CASC2D to a tropical montane watershed
Marsik, Matt; Waylen, Peter
2006-11-01
SummaryIncreased stormflow in the Quebrada Estero watershed (2.5 km 2), in the northwestern Central Valley tectonic depression of Costa Rica, reportedly has caused flooding of the city of San Ramón in recent decades. Although scientifically untested, urban expansion was deemed the cause and remedial measures were recommended by the Programa de Investigación en Desarrollo Humano Sostenible (ProDUS). CASC2D, a physically-based, spatially explicit hydrologic model, was constructed and calibrated to a June 10th 2002 storm that delivered 110.5 mm of precipitation in 4.5 h visibly exceeded the bankfull stage (0.9 m) of the Quebrada flooding portions of San Ramón. The calibrated hydrograph showed a peak discharge 16.68% (2.5 m 3 s -1) higher, an above flood stage duration 20% shorter, and time to peak discharge 11 min later than the same observed discharge hydrograph characteristics. Simulations of changing land cover conditions from 1979 to 1999 showed an increase also in the peak discharge, above flood stage duration, and time to peak discharge. Analysis using a modified location quotient identified increased urbanization in lower portions of the watershed over the time period studied. These results suggest that increased urbanization in the Quebrada Estero watershed have increased flooding peaks, and durations above threshold, confirming the ProDUS report. These results and the CASC2D model offer an easy-to-use, pragmatic planning tool for policymakers in San Ramón to assess future development scenarios and their potential flooding impacts to San Ramón.
A 2D semi-analytical model for Faraday shield in ICP source
International Nuclear Information System (INIS)
Zhang, L.G.; Chen, D.Z.; Li, D.; Liu, K.F.; Li, X.F.; Pan, R.M.; Fan, M.W.
2016-01-01
Highlights: • In this paper, a 2D model of ICP with faraday shield is proposed considering the complex structure of the Faraday shield. • Analytical solution is found to evaluate the electromagnetic field in the ICP source with Faraday shield. • The collision-free motion of electrons in the source is investigated and the results show that the electrons will oscillate along the radial direction, which brings insight into how the RF power couple to the plasma. - Abstract: Faraday shield is a thin copper structure with a large number of slits which is usually used in inductive coupled plasma (ICP) sources. RF power is coupled into the plasma through these slits, therefore Faraday shield plays an important role in ICP discharge. However, due to the complex structure of the Faraday shield, the resulted electromagnetic field is quite hard to evaluate. In this paper, a 2D model is proposed on the assumption that the Faraday shield is sufficiently long and the RF coil is uniformly distributed, and the copper is considered as ideal conductor. Under these conditions, the magnetic field inside the source is uniform with only the axial component, while the electric field can be decomposed into a vortex field generated by changing magnetic field together with a gradient field generated by electric charge accumulated on the Faraday shield surface, which can be easily found by solving Laplace's equation. The motion of the electrons in the electromagnetic field is investigated and the results show that the electrons will oscillate along the radial direction when taking no account of collision. This interesting result brings insight into how the RF power couples into the plasma.
Slope stability and rockfall assessment of volcanic tuffs using RPAS with 2-D FEM slope modelling
Török, Ákos; Barsi, Árpád; Bögöly, Gyula; Lovas, Tamás; Somogyi, Árpád; Görög, Péter
2018-02-01
Steep, hardly accessible cliffs of rhyolite tuff in NE Hungary are prone to rockfalls, endangering visitors of a castle. Remote sensing techniques were employed to obtain data on terrain morphology and to provide slope geometry for assessing the stability of these rock walls. A RPAS (Remotely Piloted Aircraft System) was used to collect images which were processed by Pix4D mapper (structure from motion technology) to generate a point cloud and mesh. The georeferencing was made by Global Navigation Satellite System (GNSS) with the use of seven ground control points. The obtained digital surface model (DSM) was processed (vegetation removal) and the derived digital terrain model (DTM) allowed cross sections to be drawn and a joint system to be detected. Joint and discontinuity system was also verified by field measurements. On-site tests as well as laboratory tests provided additional engineering geological data for slope modelling. Stability of cliffs was assessed by 2-D FEM (finite element method). Global analyses of cross sections show that weak intercalating tuff layers may serve as potential slip surfaces. However, at present the greatest hazard is related to planar failure along ENE-WSW joints and to wedge failure. The paper demonstrates that RPAS is a rapid and useful tool for generating a reliable terrain model of hardly accessible cliff faces. It also emphasizes the efficiency of RPAS in rockfall hazard assessment in comparison with other remote sensing techniques such as terrestrial laser scanning (TLS).
Deformable Registration of Biomedical Images using 2D Hidden Markov Models.
Shenoy, Renuka; Shih, Min-Chi; Rose, Kenneth
2016-07-18
Robust registration of unimodal and multimodal images is a key task in biomedical image analysis, and is often utilized as an initial step on which subsequent analysis techniques critically depend. We propose a novel probabilistic framework, based on a variant of the 2D hidden Markov model, namely the turbo hidden Markov model, to capture the deformation between pairs of images. The HMM is tailored to capture spatial transformations across images via state transitions, and modalityspecific data costs via emission probabilities. The method is derived for the unimodal setting (where simpler matching metrics may be used) as well as the multimodal setting, where different modalities may provide very different representations for a given class of objects, necessitating the use of advanced similarity measures. We utilize a rich model with hundreds of model parameters to describe the deformation relationships across such modalities. We also introduce a local edge-adaptive constraint to allow for varying degrees of smoothness between object boundaries and homogeneous regions. The parameters of the described method are estimated in a principled manner from training data via maximum likelihood learning, and the deformation is subsequently estimated using an efficient dynamic programming algorithm. Experimental results demonstrate the improved performance of the proposed approach over state-ofthe- art deformable registration techniques, on both unimodal and multimodal biomedical datasets.
Slope stability and rockfall assessment of volcanic tuffs using RPAS with 2-D FEM slope modelling
Directory of Open Access Journals (Sweden)
Á. Török
2018-02-01
Full Text Available Steep, hardly accessible cliffs of rhyolite tuff in NE Hungary are prone to rockfalls, endangering visitors of a castle. Remote sensing techniques were employed to obtain data on terrain morphology and to provide slope geometry for assessing the stability of these rock walls. A RPAS (Remotely Piloted Aircraft System was used to collect images which were processed by Pix4D mapper (structure from motion technology to generate a point cloud and mesh. The georeferencing was made by Global Navigation Satellite System (GNSS with the use of seven ground control points. The obtained digital surface model (DSM was processed (vegetation removal and the derived digital terrain model (DTM allowed cross sections to be drawn and a joint system to be detected. Joint and discontinuity system was also verified by field measurements. On-site tests as well as laboratory tests provided additional engineering geological data for slope modelling. Stability of cliffs was assessed by 2-D FEM (finite element method. Global analyses of cross sections show that weak intercalating tuff layers may serve as potential slip surfaces. However, at present the greatest hazard is related to planar failure along ENE–WSW joints and to wedge failure. The paper demonstrates that RPAS is a rapid and useful tool for generating a reliable terrain model of hardly accessible cliff faces. It also emphasizes the efficiency of RPAS in rockfall hazard assessment in comparison with other remote sensing techniques such as terrestrial laser scanning (TLS.
Breach modelling by overflow with TELEMAC 2D: comparison with largescale experiments
Directory of Open Access Journals (Sweden)
Laroche Christophe
2016-01-01
Full Text Available An erosion law has been implemented in TELEMAC 2D to represent the surface erosion process to represent the breach formation of a levee. We focus on homogeneous and earth fill levee to simplify this first implementation. The first part of this study reveals the ability of this method to represent simultaneously both formations of the breach and the scour hole at the rear of the levee. The resistance or no of the levee seems consistent with the resistance of the soil material given by a standard classification. But this first part has showed that the lateral development of the breach cannot be represented. In the second part of this study, a simply widening of the breach method based on continuous surface erosion process, has been implemented. The comparison with large scale experiments which has been made, shows that both dynamics of the breach formation and the width are not correctly estimated with the only one surface erosion process. Further developments have to be done to integrate the headcut erosion process and mass failure as sliding of the sides of the breach or undercutting.
A new model for two-dimensional numerical simulation of pseudo-2D gas-solids fluidized beds
Energy Technology Data Exchange (ETDEWEB)
Li, Tingwen; Zhang, Yongmin
2013-10-11
Pseudo-two dimensional (pseudo-2D) fluidized beds, for which the thickness of the system is much smaller than the other two dimensions, is widely used to perform fundamental studies on bubble behavior, solids mixing, or clustering phenomenon in different gas-solids fluidization systems. The abundant data from such experimental systems are very useful for numerical model development and validation. However, it has been reported that two-dimensional (2D) computational fluid dynamic (CFD) simulations of pseudo-2D gas-solids fluidized beds usually predict poor quantitative agreement with the experimental data, especially for the solids velocity field. In this paper, a new model is proposed to improve the 2D numerical simulations of pseudo-2D gas-solids fluidized beds by properly accounting for the frictional effect of the front and back walls. Two previously reported pseudo-2D experimental systems were simulated with this model. Compared to the traditional 2D simulations, significant improvements in the numerical predictions have been observed and the predicted results are in better agreement with the available experimental data.
Marine Controlled-Source Electromagnetic 2D Inversion for synthetic models.
Liu, Y.; Li, Y.
2016-12-01
We present a 2D inverse algorithm for frequency domain marine controlled-source electromagnetic (CSEM) data, which is based on the regularized Gauss-Newton approach. As a forward solver, our parallel adaptive finite element forward modeling program is employed. It is a self-adaptive, goal-oriented grid refinement algorithm in which a finite element analysis is performed on a sequence of refined meshes. The mesh refinement process is guided by a dual error estimate weighting to bias refinement towards elements that affect the solution at the EM receiver locations. With the use of the direct solver (MUMPS), we can effectively compute the electromagnetic fields for multi-sources and parametric sensitivities. We also implement the parallel data domain decomposition approach of Key and Ovall (2011), with the goal of being able to compute accurate responses in parallel for complicated models and a full suite of data parameters typical of offshore CSEM surveys. All minimizations are carried out by using the Gauss-Newton algorithm and model perturbations at each iteration step are obtained by using the Inexact Conjugate Gradient iteration method. Synthetic test inversions are presented.
Fast numerical simulations of 2D turbulence using a dynamic model for subfilter motions
International Nuclear Information System (INIS)
Laval, J.-P.; Dubrulle, B.; Nazarenko, S.V.
2004-01-01
We present numerical simulations of 2D turbulent flow using a new model for the subfilter scales which are computed using a dynamic equation linking the subfilter scales with the resolved velocity. This equation is not postulated, but derived from the constitutive equations under the assumption that the non-linear interactions of subfilter scales between themselves are small compared to their distortions by the resolved scales. Such an assumption results in a linear stochastic equation for the subfilter scales, which can be numerically solved by a decomposition of the subfilter scales into localized wave packets. The wave packets are randomly produced by the smallest of the resolved scales. They are further transported by the resolved-scale velocity and they have wavenumbers and amplitudes which evolve according to the resolved strain. Performance of our model is compared with direct numerical simulations of decaying and forced turbulence. For the same resolution, numerical simulations using our model allow for a significant reduction of the computational time (of the order of 100 in the case we consider), and allow to achieve of significantly larger Reynolds number than the direct method
2d Affine XY-Spin Model/4d Gauge Theory Duality and Deconfinement
Energy Technology Data Exchange (ETDEWEB)
Anber, Mohamed M.; Poppitz, Erich; /Toronto U.; Unsal, Mithat; /SLAC /Stanford U., Phys. Dept. /San Francisco State U.
2012-08-16
We introduce a duality between two-dimensional XY-spin models with symmetry-breaking perturbations and certain four-dimensional SU(2) and SU(2) = Z{sub 2} gauge theories, compactified on a small spatial circle R{sup 1,2} x S{sup 1}, and considered at temperatures near the deconfinement transition. In a Euclidean set up, the theory is defined on R{sup 2} x T{sup 2}. Similarly, thermal gauge theories of higher rank are dual to new families of 'affine' XY-spin models with perturbations. For rank two, these are related to models used to describe the melting of a 2d crystal with a triangular lattice. The connection is made through a multi-component electric-magnetic Coulomb gas representation for both systems. Perturbations in the spin system map to topological defects in the gauge theory, such as monopole-instantons or magnetic bions, and the vortices in the spin system map to the electrically charged W-bosons in field theory (or vice versa, depending on the duality frame). The duality permits one to use the two-dimensional technology of spin systems to study the thermal deconfinement and discrete chiral transitions in four-dimensional SU(N{sub c}) gauge theories with n{sub f} {ge} 1 adjoint Weyl fermions.
In vitro systems to study nephropharmacology : 2D versus 3D models
Sánchez-Romero, Natalia; Schophuizen, Carolien M S; Giménez, Ignacio; Masereeuw, Rosalinde
2016-01-01
The conventional 2-dimensional (2D) cell culture is an invaluable tool in, amongst others, cell biology and experimental pharmacology. However, cells cultured in 2D, on the top of stiff plastic plates lose their phenotypical characteristics and fail in recreating the physiological environment found
Automatic 3D high-fidelity traffic interchange modeling using 2D road GIS data
Wang, Jie; Shen, Yuzhong
2011-03-01
3D road models are widely used in many computer applications such as racing games and driving simulations. However, almost all high-fidelity 3D road models were generated manually by professional artists at the expense of intensive labor. There are very few existing methods for automatically generating 3D high-fidelity road networks, especially for those existing in the real world. Real road network contains various elements such as road segments, road intersections and traffic interchanges. Among them, traffic interchanges present the most challenges to model due to their complexity and the lack of height information (vertical position) of traffic interchanges in existing road GIS data. This paper proposes a novel approach that can automatically produce 3D high-fidelity road network models, including traffic interchange models, from real 2D road GIS data that mainly contain road centerline information. The proposed method consists of several steps. The raw road GIS data are first preprocessed to extract road network topology, merge redundant links, and classify road types. Then overlapped points in the interchanges are detected and their elevations are determined based on a set of level estimation rules. Parametric representations of the road centerlines are then generated through link segmentation and fitting, and they have the advantages of arbitrary levels of detail with reduced memory usage. Finally a set of civil engineering rules for road design (e.g., cross slope, superelevation) are selected and used to generate realistic road surfaces. In addition to traffic interchange modeling, the proposed method also applies to other more general road elements. Preliminary results show that the proposed method is highly effective and useful in many applications.
2D spectral element modeling of GPR wave propagation in inhomogeneous media
Zarei, Sajad; Oskooi, Behrooz; Amini, Navid; Dalkhani, Amin Rahimi
2016-10-01
We present a spectral element method, for simulation of ground-penetrating radar (GPR) in two dimensions. The technique is based upon a weak formulation of the equations of Maxwell and combines the flexibility of the elemental-based methods with the accuracy of the spectral based methods. The wave field on the elements is discretized using high-degree Lagrange interpolation and integration over an element is accomplished based upon the Gauss-Lobatto-Legendre integration rule. As a result, the mass matrix and the damping matrix are always diagonal, which drastically reduces the computational cost. We first develop the formulation of 2D spectral element method (SEM) in the time-domain based on Maxwell's equations. The presented formulation is with matrix notation that simplifies the implementation of the relations in computer programs, especially in MATLAB application. We discuss the differences between spectral element method and finite-element method in the time-domain. Also, we show that the SEM numerical dispersion is much lower than FEM. To absorb waves at the edges of the modeling domain, we implement first order Clayton and Engquist absorbing boundary conditions (CE-ABC) introduced in numerical finite-difference modeling of seismic wave propagation. We used the SEM to simulate a complex model to show its abilities and limitations. As well as, one distinct advantage of SEM is that we can easily define our model features in nodal points, because the integration points and the interpolation points are similar that makes it very flexible in simulation of complex models.
Magunia, Harry; Schmid, Eckhard; Hilberath, Jan N; Häberle, Leo; Grasshoff, Christian; Schlensak, Christian; Rosenberger, Peter; Nowak-Machen, Martina
2017-04-01
The early diagnosis and treatment of right ventricular (RV) dysfunction are of critical importance in cardiac surgery patients and impact clinical outcome. Two-dimensional (2D) transesophageal echocardiography (TEE) can be used to evaluate RV function using surrogate parameters due to complex RV geometry. The aim of this study was to evaluate whether the commonly used visual evaluation of RV function and size using 2D TEE correlated with the calculated three-dimensional (3D) volumetric models of RV function. Retrospective study, single center, University Hospital. Seventy complete datasets were studied consisting of 2D 4-chamber view loops (2-3 beats) and the corresponding 4-chamber view 3D full-volume loop of the right ventricle. RV function and RV size of the 2D loops then were assessed retrospectively purely qualitatively individually by 4 clinician echocardiographers certified in perioperative TEE. Corresponding 3D volumetric models calculating RV ejection fraction and RV end-diastolic volumes then were established and compared with the 2D assessments. 2D assessment of RV function correlated with 3D volumetric calculations (Spearman's rho -0.5; pright ventricular function based on visual estimation as frequently used in clinical practice appeared to be a reliable method of RV functional evaluation. However, 2D assessment of RV size seemed unreliable and should be used with caution. Copyright © 2017 Elsevier Inc. All rights reserved.
Conformal internal symmetry of 2d σ-models coupled to gravity and a dilaton
International Nuclear Information System (INIS)
Julia, B.; Nicolai, H.
1996-08-01
General relativity reduced to two dimensions possesses a large group of symmetries that exchange classical solutions. The associated Lie algebra is known to contain the affine Kac-Moody algebra A 1 (1) and half of a real Witt algebra. In this paper we exhibit the full symmetry under the semi-direct product of Lie(A 1 (1) ) by the Witt algebra Lie(W). Furthermore we exhibit the corresponding hidden gauge symmetries. We show that the theory can be understood in terms of an infinite dimensional potential space involving all degrees of freedom: The dilaton as well as matter and gravitation. In the dilaton sector the linear system that extends the previously known Lax pair has the form of a twisted self-duality constraint that is the analog of the self-duality constraint arising in extended supergravities in higher spacetime dimensions. Our results furnish a group theoretical explanation for the simultaneous occurrence of two spectral parameters, a constant one (=y) and a variable one (=t). They hold for all 2d non-linear σ-models that are obtained by dimensional reduction of G/H models in three dimensions coupled to pure gravity. In that case the Lie algebra is Lie(W∝G (1) ); this symmetry acts on a set of off shell fields (in a fixed gauge) and preserves the equations of motion. (orig.)
Conformal internal symmetry of 2d σ-models coupled to gravity and a dilaton
International Nuclear Information System (INIS)
Julia, B.
1996-01-01
General relativity reduced to two dimensions possesses a large group of symmetries that exchange classical solutions. The associated Lie algebra is known to contain the affine Kac-Moody algebra A 1 (1) and half of a real Witt algebra. In this paper we exhibit the full symmetry under the semi-direct product of Lie(A 1 (1) ) by the Witt algebra Lie(W). Furthermore we exhibit the corresponding hidden gauge symmetries. We show that the theory can be understood in terms of an infinite dimensional potential space involving all degrees of freedom: the dilaton as well as matter and gravitation. In the dilaton sector the linear system that extends the previously known Lax pair has the form of a twisted self-duality constraint that is the analog of the self-duality constraint arising in extended supergravities in higher space-time dimensions. Our results furnish a group theoretical explanation for the simultaneous occurrence of two spectral parameters, a constant one (=y) and a variable one (=t). They hold for all 2d non-linear σ-models that are obtained by dimensional reduction of G/H models in three dimensions coupled to pure gravity. (orig./WL) (orig.)
PREDICTION OF BLOOD FLOW VELOCITY AND LEAFLET DEFORMATION VIA 2D MITRAL VALVE MODEL
Directory of Open Access Journals (Sweden)
M.A.H. Mohd Adib
2012-06-01
Full Text Available In the mitral valve, regional variations in structure and material properties combine to affect the biomechanics of the entire valve. From previous studies, we know that the mitral valve leaflet tissue is highly extensible. A two-dimensional model of the mitral valve was generated using an Arbitrary Lagrangian-Eulerian (ALE mesh. A simple approximation of the heart geometry was used and the valve dimensions were based on actual measurements made. Valve opening and closure was simulated using contact equations. The objective of this study was to investigate and predict flow and leaflet phenomena via a simple 2D mitral valve model based on the critical parameter of blood. Two stages of mitral valves analysis were investigated: the systolic and diastolic stages. The results show a linear correlation between the mitral valve leaflet rigidity and the volume of backflow. Additionally, the simulation predicted mitral valve leaflet displacement during closure, which agreed with the results of our previous data analysis and the results for blood flow velocity during systole condition through the mitral valve outlet, as reported in the medical literature. In conclusion, these computational techniques are very useful in the study of both degenerative valve disease and failure of prostheses and will be further developed to investigate heart valve failure and subsequent surgical repair.
Passive object detection from pressure sensing using a 2-D viscous fluid model
Clark, Jack; Park, Jeongyong; Dahl, Jason
2017-11-01
Embedded pressure sensors have the ability to inform an object about the surrounding flow environment. Fish demonstrate this ability through the use of their lateral line system, which enables complex behaviors (feeding, schooling, etc.) based on measures of pressure on the surface of the body. Previous work has shown that inviscid models may be used for identifying object shapes or local flow structures based on several measurements of pressure, though these models fail to capture flow structures with large viscous effects or complex object shapes. In the present study, 2-D simulations are performed for a NACA 0012 foil passing by an object on a wall. The simulations vary object shape and size, demonstrating distinct wake behavior through pressure. A classifier is developed based on the pressure time histories in order to classify object shape and size, and demonstrated to work well using under-resolved simulated data. Experiments are also performed for a subset of object shapes and sizes. The experiments include physical sources of noise such as free surface disturbances and electrical noise to demonstrate the feasibility of this object recognition process. The classifier is tested against the physical measurements and compared with the simulated results. Office of Naval Research (Grant No: N00014-16-1-2968).
2D modelling of a UF6 container in a fire
International Nuclear Information System (INIS)
Duret, B.; Seiler, J.M.
1993-01-01
We present some results on 2D thermal modelisation of the behaviour of UF6 in a fire. A cylindrical container is engulfed by a high temperature space where the heat transfer is expected to occur by radiation only. During the first minutes, we assume that the thermal resistance is between the external wall and the UF6 solid, the heat transfer can be split up into three kinds: 1) conduction to solid UF6 through a contact surface. 2) radiative transfer. 3) gas layer with a small heat conductance. This thermal resistance is initially determined by the UF6 filling type, shape and also is time dependant by thermal dilatation effects. On the onset of liquifying the heat transfer increases because of the larger liquid exchange. The liquid and boiling heat flow is then calculated by a model on the basis of classical correlations in vertical cavities. Numerical evaluations have been performed with a finite element model using: ANSYS. With a realistic hypothesis, the effect of the following parameters is estimated: thermal conductivity of UF6 solid, contact surface fraction, UF6 emissivity, gas gap thickness, liquid UF6 wall exchange, solid liquid transition criteria, non condensation factor k. (J.P.N.)
Comparison between a 1D and a 2D numerical model of an active magnetic regenerative refrigerator
DEFF Research Database (Denmark)
Petersen, Thomas Frank; Engelbrecht, Kurt; Bahl, Christian Robert Haffenden
2008-01-01
The active magnetic regenerator (AMR) refrigeration system represents an environmentally attractive alternative to vapour-compression refrigeration. This paper compares the results of two numerical AMR models: (1) a 1D finite difference model and (2) a 2D finite element model. Both models simulate...
Electrical resistivity tomography applied to a complex lava dome: 2D and 3D models comparison
Portal, Angélie; Fargier, Yannick; Lénat, Jean-François; Labazuy, Philippe
2015-04-01
The study of volcanic domes growth (e.g. St. Helens, Unzen, Montserrat) shows that it is often characterized by a succession of extrusion phases, dome explosions and collapse events. Lava dome eruptive activity may last from days to decades. Therefore, their internal structure, at the end of the eruption, is complex and includes massive extrusions and lava lobes, talus and pyroclastic deposits as well as hydrothermal alteration. The electrical resistivity tomography (ERT) method, initially developed for environmental and engineering exploration, is now commonly used for volcano structure imaging. Because a large range of resistivity values is often observed in volcanic environments, the method is well suited to study the internal structure of volcanic edifices. We performed an ERT survey on an 11ka years old trachytic lava dome, the Puy de Dôme volcano (French Massif Central). The analysis of a recent high resolution DEM (LiDAR 0.5 m), as well as other geophysical data, strongly suggest that the Puy de Dôme is a composite dome. 11 ERT profiles have been carried out, both at the scale of the entire dome (base diameter of ~2 km and height of 400 m) on the one hand, and at a smaller scale on the summit part on the other hand. Each profile is composed of 64 electrodes. Three different electrode spacing have been used depending on the study area (35 m for the entire dome, 10 m and 5 m for its summit part). Some profiles were performed with half-length roll-along acquisitions, in order to keep a good trade-off between depth of investigation and resolution. Both Wenner-alpha and Wenner-Schlumberger protocols were used. 2-D models of the electrical resistivity distribution were computed using RES2DINV software. In order to constrain inversion models interpretation, the depth of investigation (DOI) method was applied to those results. It aims to compute a sensitivity index on inversion results, illustrating how the data influence the model and constraining models
Modeling of two-storey precast school building using Ruaumoko 2D program
International Nuclear Information System (INIS)
Hamid, N. H.; Tarmizi, L. H.; Ghani, K. D.
2015-01-01
The long-distant earthquake loading from Sumatra and Java Island had caused some slight damages to precast and reinforced concrete buildings in West Malaysia such as cracks on wall panels, columns and beams. Subsequently, the safety of existing precast concrete building is needed to be analyzed because these buildings were designed using BS 8110 which did not include the seismic loading in the design. Thus, this paper emphasizes on the seismic performance and dynamic behavior of precast school building constructed in Malaysia under three selected past earthquakes excitations ; El Centro 1940 North-South, El Centro East-West components and San Fernando 1971 using RUAUMOKO 2D program. This program is fully utilized by using prototype precast school model and dynamic non-linear time history analysis. From the results, it can be concluded that two-storey precast school building has experienced severe damage and partial collapse especially at beam-column joint under San Fernando and El Centro North-South Earthquake as its exceeds the allowable inter-storey drift and displacement as specified in Eurocode 8. The San Fernando earthquake has produced a massive destruction to the precast building under viscous damping, ξ = 5% and this building has generated maximum building displacement of 435mm, maximum building drift of 0.68% and maximum bending moment at 8458kNm
Krali, Emiljana; Curry, Richard J
2011-04-26
To improve the efficiency of organic photovoltaic devices the inclusion of semiconducting nanoparticles such as PbS has been used to enhance near-infrared absorption. Additionally the use of interdigitated heterojunctions has been explored as a means of improving charge extraction. In this paper we provide a two-dimensional model taking into account these approaches with the aim of predicting an optimized device geometry to maximize the efficiency. The steady-state exciton population has been calculated in each of the active regions taking into account the full optical response based on using a finite difference approach to obtain approximate numerical solutions to the 2D exciton diffusion equation. On the basis of this we calculate the contribution of each active material to the device short circuit current and power conversion efficiency. We show that optimized structures can lead to power conversions efficiencies of ∼50% compared to a maximum of ∼17% for planar heterojunction devices. To achieve this the interdigitated region thickness should be ∼800 nm with PbS and C(60) widths of ∼60 and 20 nm, respectively. Even modest nanopatterning using much thinner active regions provides improvements in efficiency and may be approached using a variety of methods including nanoimprinting lithography, nanotemplating, or the incorporation of presynthesized nanorod structures.
Modeling of two-storey precast school building using Ruaumoko 2D program
Energy Technology Data Exchange (ETDEWEB)
Hamid, N. H.; Tarmizi, L. H.; Ghani, K. D. [Faculty of Civil Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia)
2015-05-15
The long-distant earthquake loading from Sumatra and Java Island had caused some slight damages to precast and reinforced concrete buildings in West Malaysia such as cracks on wall panels, columns and beams. Subsequently, the safety of existing precast concrete building is needed to be analyzed because these buildings were designed using BS 8110 which did not include the seismic loading in the design. Thus, this paper emphasizes on the seismic performance and dynamic behavior of precast school building constructed in Malaysia under three selected past earthquakes excitations ; El Centro 1940 North-South, El Centro East-West components and San Fernando 1971 using RUAUMOKO 2D program. This program is fully utilized by using prototype precast school model and dynamic non-linear time history analysis. From the results, it can be concluded that two-storey precast school building has experienced severe damage and partial collapse especially at beam-column joint under San Fernando and El Centro North-South Earthquake as its exceeds the allowable inter-storey drift and displacement as specified in Eurocode 8. The San Fernando earthquake has produced a massive destruction to the precast building under viscous damping, ξ = 5% and this building has generated maximum building displacement of 435mm, maximum building drift of 0.68% and maximum bending moment at 8458kNm.
Modeling of two-storey precast school building using Ruaumoko 2D program
Hamid, N. H.; Tarmizi, L. H.; Ghani, K. D.
2015-05-01
The long-distant earthquake loading from Sumatra and Java Island had caused some slight damages to precast and reinforced concrete buildings in West Malaysia such as cracks on wall panels, columns and beams. Subsequently, the safety of existing precast concrete building is needed to be analyzed because these buildings were designed using BS 8110 which did not include the seismic loading in the design. Thus, this paper emphasizes on the seismic performance and dynamic behavior of precast school building constructed in Malaysia under three selected past earthquakes excitations ; El Centro 1940 North-South, El Centro East-West components and San Fernando 1971 using RUAUMOKO 2D program. This program is fully utilized by using prototype precast school model and dynamic non-linear time history analysis. From the results, it can be concluded that two-storey precast school building has experienced severe damage and partial collapse especially at beam-column joint under San Fernando and El Centro North-South Earthquake as its exceeds the allowable inter-storey drift and displacement as specified in Eurocode 8. The San Fernando earthquake has produced a massive destruction to the precast building under viscous damping, ξ = 5% and this building has generated maximum building displacement of 435mm, maximum building drift of 0.68% and maximum bending moment at 8458kNm.
Stability of superfluid phases in the 2D spin-polarized attractive Hubbard model
Kujawa-Cichy, A.; Micnas, R.
2011-08-01
We study the evolution from the weak coupling (BCS-like limit) to the strong coupling limit of tightly bound local pairs (LPs) with increasing attraction, in the presence of the Zeeman magnetic field (h) for d=2, within the spin-polarized attractive Hubbard model. The broken symmetry Hartree approximation as well as the strong coupling expansion are used. We also apply the Kosterlitz-Thouless (KT) scenario to determine the phase coherence temperatures. For spin-independent hopping integrals (t↑=t↓), we find no stable homogeneous polarized superfluid (SCM) state in the ground state for the strong attraction and obtain that for a two-component Fermi system on a 2D lattice with population imbalance, phase separation (PS) is favoured for a fixed particle concentration, even on the LP (BEC) side. We also examine the influence of spin-dependent hopping integrals (mass imbalance) on the stability of the SCM phase. We find a topological quantum phase transition (Lifshitz type) from the unpolarized superfluid phase (SC0) to SCM and tricritical points in the h-|U| and t↑/t↓-|U| ground-state phase diagrams. We also construct the finite temperature phase diagrams for both t↑=t↓ and t↑≠t↓ and analyze the possibility of occurrence of a spin-polarized KT superfluid.
Approaches to Modeling Coupled Flow and Reaction in a 2-D Cementation Experiment
Energy Technology Data Exchange (ETDEWEB)
Steefel, Carl; Cochepin, B.; Trotignon, L.; Bildstein, O.; Steefel, C.; Lagneau, V.; van der Lee, J.
2008-04-01
Porosity evolution at reactive interfaces is a key process that governs the evolution and performances of many engineered systems that have important applications in earth and environmental sciences. This is the case, for example, at the interface between cement structures and clays in deep geological nuclear waste disposals. Although in a different transport regime, similar questions arise for permeable reactive barriers used for biogeochemical remediation in surface environments. The COMEDIE project aims at investigating the coupling between transport, hydrodynamics and chemistry when significant variations of porosity occur. The present work focuses on a numerical benchmark used as a design exercise for the future COMEDIE-2D experiment. The use of reactive transport simulation tools like Hytec and Crunch provides predictions of the physico-chemical evolutions that are expected during the future experiments in laboratory. Focus is given in this paper on the evolution during the simulated experiment of precipitate, permeability and porosity fields. A first case is considered in which the porosity is constant. Results obtained with Crunch and Hytec are in relatively good agreement. Differences are attributable to the models of reactive surface area taken into account for dissolution/precipitation processes. Crunch and Hytec simulations taking into account porosity variations are then presented and compared. Results given by the two codes are in qualitative agreement, with differences attributable in part to the models of reactive surface area for dissolution/precipitation processes. As a consequence, the localization of secondary precipitates predicted by Crunch leads to lower local porosities than for predictions obtained by Hytec and thus to a stronger coupling between flow and chemistry. This benchmark highlights the importance of the surface area model employed to describe systems in which strong porosity variations occur as a result of dissolution
D Recording for 2d Delivering - the Employment of 3d Models for Studies and Analyses -
Rizzi, A.; Baratti, G.; Jiménez, B.; Girardi, S.; Remondino, F.
2011-09-01
In the last years, thanks to the advances of surveying sensors and techniques, many heritage sites could be accurately replicated in digital form with very detailed and impressive results. The actual limits are mainly related to hardware capabilities, computation time and low performance of personal computer. Often, the produced models are not visible on a normal computer and the only solution to easily visualized them is offline using rendered videos. This kind of 3D representations is useful for digital conservation, divulgation purposes or virtual tourism where people can visit places otherwise closed for preservation or security reasons. But many more potentialities and possible applications are available using a 3D model. The problem is the ability to handle 3D data as without adequate knowledge this information is reduced to standard 2D data. This article presents some surveying and 3D modeling experiences within the APSAT project ("Ambiente e Paesaggi dei Siti d'Altura Trentini", i.e. Environment and Landscapes of Upland Sites in Trentino). APSAT is a multidisciplinary project funded by the Autonomous Province of Trento (Italy) with the aim documenting, surveying, studying, analysing and preserving mountainous and hill-top heritage sites located in the region. The project focuses on theoretical, methodological and technological aspects of the archaeological investigation of mountain landscape, considered as the product of sequences of settlements, parcelling-outs, communication networks, resources, and symbolic places. The mountain environment preserves better than others the traces of hunting and gathering, breeding, agricultural, metallurgical, symbolic activities characterised by different lengths and environmental impacts, from Prehistory to the Modern Period. Therefore the correct surveying and documentation of this heritage sites and material is very important. Within the project, the 3DOM unit of FBK is delivering all the surveying and 3D material to
Ghassoun, Yahya; Löwner, Marc-Oliver
2017-10-01
Total particle number concentration (TNC) was studied in a 1 × 2 km area in Berlin, the capital of Germany by three Land Use Regression models (LUR). The estimation of TNC was established and compared using one 2D-LUR and two 3D-LUR models. All models predict total number concentrations TNC by using urban morphological (2D resp. 3D) and additional semantical parameters. 2D and semantical parameters were derived from Open Street Map data (OSM) whereas 3D parameters were derived from a CityGML-based 3D city model. While the models are capable to depict the spatial variation of TNC across the study area, the two 3D-LUR showed better results than the 2D-LUR. The 2D-LUR model explained 74% of the variance of TNC for the full data set with root mean square error (RMSE) of 4014 cm-3 while the 3D-LUR explained 79% of the variance with an RMSE of 3477 cm-3. The further introduction of a new spatial parameter, the Frontal Area Index (FAI) that represents the dynamic factor wind direction enhanced the 3D-LUR to explain 82% of the variance with RMSE of 3389 cm-3. Furthermore, the semantical parameters (e.g. streets type) played a significant role in all models.
Ng, Z. F.; Gisen, J. I.; Akbari, A.
2018-03-01
Topography dataset is an important input in performing flood inundation modelling. However, it is always difficult to obtain high resolution topography that provide accurate elevation information. Fortunately, there are some open source topography datasets available with reasonable resolution such as SRTM and ASTER-GDEM. In Malaysia particularly in Kuantan, the modelling research on the floodplain area is still lacking. This research aims to: a) to investigate the suitability of ASTER-GDEM to be applied in the 1D-2D flood inundation modelling for the Kuantan River Basin; b) to generate flood inundation map for Kuantan river basin. The topography dataset used in this study is ASTER-GDEM to generate physical characteristics of watershed in the basin. It is used to perform rainfall runoff modelling for hydrological studies and to delineate flood inundation area in the Flood Modeller. The results obtained have shown that a 30m resolution ASTER-GDEM is applicable as an input for the 1D-2D flood modelling. The simulated water level in 2013 has NSE of 0.644 and RSME of 1.259. As a conclusion, ASTER-GDEM can be used as one alternative topography datasets for flood inundation modelling. However, the flood level obtained from the hydraulic modelling shows low accuracy at flat urban areas.
Modeling Cellular Networks with Full Duplex D2D Communication: A Stochastic Geometry Approach
Ali, Konpal S.
2016-08-24
Full-duplex (FD) communication is optimistically promoted to double the spectral efficiency if sufficient self-interference cancellation (SIC) is achieved. However, this is not true when deploying FD-communication in a large-scale setup due to the induced mutual interference. Therefore, a large-scale study is necessary to draw legitimate conclusions about gains associated with FD-communication. This paper studies the FD operation for underlay device-to-device (D2D) communication sharing the uplink resources in cellular networks. We propose a disjoint fine-tuned selection criterion for the D2D and FD modes of operation. Then, we develop a tractable analytical paradigm, based on stochastic geometry, to calculate the outage probability and rate for cellular and D2D users. The results reveal that even in the case of perfect SIC, due to the increased interference injected to the network by FD-D2D communication, having all proximity UEs transmit in FD-D2D is not beneficial for the network. However, if the system parameters are carefully tuned, non-trivial network spectral-efficiency gains (64% shown) can be harvested. We also investigate the effects of imperfect SIC and D2D-link distance distribution on the harvested FD gains.
Modelling thermal stratification in the North Sea: Application of a 2-D potential energy model
DEFF Research Database (Denmark)
Nielsen, Morten Holtegaard; St. John, Michael
2001-01-01
dynamics we have developed and tested a potential energy model of thermal stratification based on the energy equation (for turbulence). The energy equation relates the temporal and spatial changes of turbulent kinetic energy (TKE), the production of TKE and the dissipation of TKE to the change of potential...... energy as water masses of different densities are mixed in the field of gravity. A constant ratio between the gain in potential energy and the production of TKE is assumed, known as the flux Richardson number. The model is comprised of 0·5m vertical layers with a temporal time step of 1 day. The model...... is forced with wind, dew point temperature from Ekofisk oilfield in the central North Sea, and tidal current and atmospheric radiation. The model is used to simulate the seasonal cycle of stratification in the central North Sea in the years 1988, 1989 and 1990 and is compared to density profiles...
2D Global Rayleigh Wave Attenuation Model Using Finite Frequency Focusing and Defocusing Theory
Ma, Z.; Masters, G.; Dalton, C. A.
2015-12-01
We have developed an efficient technique to process and measure surface-wave amplitude and phase from a large collection of seismic waveforms. These amplitude and phase data sets are used to jointly invert for 2D phase velocity and attenuation maps. As demonstrated by Dalton and Ekstrom (2006), correcting for the effects of focusing and defocusing by elastic structure is crucial in order to obtain reliable attenuation structures. A robust theory that can reliably predict focusing-defocusing effects and is insensitive to the details of making the phase velocity maps is preferred. Great circle ray theory can give useful predictions for the focusing-defocusing effects if careful attention is paid to how the phase velocity model is smoothed. However, the predictions of the finite frequency kernels are more robust at the low-intermediate frequency range (below 25mHz) and suggest that they are better suited as a basis for inversion.We invert for the phase velocity, attenuation, source, and receiver terms simultaneously. Our models provide 60-70% variance reduction to the raw data though the source terms are the biggest contribution to the fit of the data. The attenuation maps show structures that correlate well with surface tectonics and the age-dependent trend of attenuation is clearly seen in the ocean basins. We have also identified problematic stations and earthquake sources as a by-product of our data selection process. Although our approach was developed for a global study, it can be extended to regional studies. Our first regional-scale application of this approach is to the Atlantic upper mantle.
Building a 2.5D Digital Elevation Model from 2D Imagery
Padgett, Curtis W.; Ansar, Adnan I.; Brennan, Shane; Cheng, Yang; Clouse, Daniel S.; Almeida, Eduardo
2013-01-01
When projecting imagery into a georeferenced coordinate frame, one needs to have some model of the geographical region that is being projected to. This model can sometimes be a simple geometrical curve, such as an ellipse or even a plane. However, to obtain accurate projections, one needs to have a more sophisticated model that encodes the undulations in the terrain including things like mountains, valleys, and even manmade structures. The product that is often used for this purpose is a Digital Elevation Model (DEM). The technology presented here generates a high-quality DEM from a collection of 2D images taken from multiple viewpoints, plus pose data for each of the images and a camera model for the sensor. The technology assumes that the images are all of the same region of the environment. The pose data for each image is used as an initial estimate of the geometric relationship between the images, but the pose data is often noisy and not of sufficient quality to build a high-quality DEM. Therefore, the source imagery is passed through a feature-tracking algorithm and multi-plane-homography algorithm, which refine the geometric transforms between images. The images and their refined poses are then passed to a stereo algorithm, which generates dense 3D data for each image in the sequence. The 3D data from each image is then placed into a consistent coordinate frame and passed to a routine that divides the coordinate frame into a number of cells. The 3D points that fall into each cell are collected, and basic statistics are applied to determine the elevation of that cell. The result of this step is a DEM that is in an arbitrary coordinate frame. This DEM is then filtered and smoothed in order to remove small artifacts. The final step in the algorithm is to take the initial DEM and rotate and translate it to be in the world coordinate frame [such as UTM (Universal Transverse Mercator), MGRS (Military Grid Reference System), or geodetic] such that it can be saved in
Croissant, Thomas; Lague, Dimitri; Davy, Philippe; Steer, Philippe
2016-04-01
In active mountain ranges, large earthquakes (Mw > 5-6) trigger numerous landslides that impact river dynamics. These landslides bring local and sudden sediment piles that will be eroded and transported along the river network causing downstream changes in river geometry, transport capacity and erosion efficiency. The progressive removal of landslide materials has implications for downstream hazards management and also for understanding landscape dynamics at the timescale of the seismic cycle. The export time of landslide-derived sediments after large-magnitude earthquakes has been studied from suspended load measurements but a full understanding of the total process, including the coupling between sediment transfer and channel geometry change, still remains an issue. Note that the transport of small sediment pulses has been studied in the context of river restoration, but the magnitude of sediment pulses generated by landslides may make the problem different. Here, we study the export of large volumes (>106 m3) of sediments with the 2D hydro-morphodynamic model, Eros. This model uses a new hydrodynamic module that resolves a reduced form of the Saint-Venant equations with a particle method. It is coupled with a sediment transport and lateral and vertical erosion model. Eros accounts for the complex retroactions between sediment transport and fluvial geometry, with a stochastic description of the floods experienced by the river. Moreover, it is able to reproduce several features deemed necessary to study the evacuation of large sediment pulses, such as river regime modification (single-thread to multi-thread), river avulsion and aggradation, floods and bank erosion. Using a synthetic and simple topography we first present how granulometry, landslide volume and geometry, channel slope and flood frequency influence 1) the dominance of pulse advection vs. diffusion during its evacuation, 2) the pulse export time and 3) the remaining volume of sediment in the catchment
Weinger, Jason G; Plaisted, Warren C; Maciejewski, Sonia M; Lanier, Lewis L; Walsh, Craig M; Lane, Thomas E
2014-10-01
Transplantation of major histocompatibility complex-mismatched mouse neural precursor cells (NPCs) into mice persistently infected with the neurotropic JHM strain of mouse hepatitis virus (JHMV) results in rapid rejection that is mediated, in part, by T cells. However, the contribution of the innate immune response to allograft rejection in a model of viral-induced neurological disease has not been well defined. Herein, we demonstrate that the natural killer (NK) cell-expressing-activating receptor NKG2D participates in transplanted allogeneic NPC rejection in mice persistently infected with JHMV. Cultured NPCs derived from C57BL/6 (H-2(b) ) mice express the NKG2D ligand retinoic acid early precursor transcript (RAE)-1 but expression was dramatically reduced upon differentiation into either glia or neurons. RAE-1(+) NPCs were susceptible to NK cell-mediated killing whereas RAE-1(-) cells were resistant to lysis. Transplantation of C57BL/6-derived NPCs into JHMV-infected BALB/c (H-2(d) ) mice resulted in infiltration of NKG2D(+) CD49b(+) NK cells and treatment with blocking antibody specific for NKG2D increased survival of allogeneic NPCs. Furthermore, transplantation of differentiated RAE-1(-) allogeneic NPCs into JHMV-infected BALB/c mice resulted in enhanced survival, highlighting a role for the NKG2D/RAE-1 signaling axis in allograft rejection. We also demonstrate that transplantation of allogeneic NPCs into JHMV-infected mice resulted in infection of the transplanted cells suggesting that these cells may be targets for infection. Viral infection of cultured cells increased RAE-1 expression, resulting in enhanced NK cell-mediated killing through NKG2D recognition. Collectively, these results show that in a viral-induced demyelination model, NK cells contribute to rejection of allogeneic NPCs through an NKG2D signaling pathway. © 2014 AlphaMed Press.
Fekkes, S.; Swillens, A.E.; Hansen, H.H.G.; Saris, A.E.C.M.; Nillesen, M.M.; Iannaccone, F.; Segers, P.; Korte, C.L. de
2016-01-01
Three-dimensional (3-D) strain estimation might improve the detection and localization of high strain regions in the carotid artery (CA) for identification of vulnerable plaques. This paper compares 2-D versus 3-D displacement estimation in terms of radial and circumferential strain using simulated
2009-09-01
FVCOM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 2.7 ICOM ...coastal re- gions featured with complex irregular geometry and steep bottom topography. ICOM Imperial College Ocean Model FEM (CG and DG) using...the ICOM group. This code is written in C. Finel was also developed by the same group, and it is a three-dimensional non- hydrostatic finite element
DEFF Research Database (Denmark)
Davidsen, Steffen; Löwe, Roland; Thrysøe, Cecilie
2017-01-01
Evaluation of pluvial flood risk is often based on computations using 1D/2D urban flood models. However, guidelines on choice of model complexity are missing, especially for one-dimensional (1D) network models. This study presents a new automatic approach for simplification of 1D hydraulic networks...... nodes eliminated connection to some areas. This promoted errors in two-dimensional (2D) flood results with changes in spatial location of flooding in the reduced 1D/2D models. Applying delayed rain inputs to compensate for changes in travel time and preserving network volume by expanding node diameters...... did not improve overall results. Investigations on the expected annual damages (EAD) showed that differences in EAD are smaller than deviations in the simulated flooded areas, suggesting that spatial changes are limited to local displacements. Probably, minor improvements of the simplification...
DEFF Research Database (Denmark)
Davidsen, Steffen; Löwe, Roland; Thrysøe, Cecilie
2017-01-01
Evaluation of pluvial flood risk is often based on computations using 1D/2D urban flood models. However, guidelines on choice of model complexity are missing, especially for one-dimensional (1D) network models. This study presents a new automatic approach for simplification of 1D hydraulic networks...... did not improve overall results. Investigations on the expected annual damages (EAD) showed that differences in EAD are smaller than deviations in the simulated flooded areas, suggesting that spatial changes are limited to local displacements. Probably, minor improvements of the simplification...... nodes eliminated connection to some areas. This promoted errors in two-dimensional (2D) flood results with changes in spatial location of flooding in the reduced 1D/2D models. Applying delayed rain inputs to compensate for changes in travel time and preserving network volume by expanding node diameters...
Comparative Analysis of Bulge Deformation between 2D and 3D Finite Element Models
Directory of Open Access Journals (Sweden)
Qin Qin
2014-02-01
Full Text Available Bulge deformation of the slab is one of the main factors that affect slab quality in continuous casting. This paper describes an investigation into bulge deformation using ABAQUS to model the solidification process. A three-dimensional finite element analysis model of the slab solidification process has been first established because the bulge deformation is closely related to slab temperature distributions. Based on slab temperature distributions, a three-dimensional thermomechanical coupling model including the slab, the rollers, and the dynamic contact between them has also been constructed and applied to a case study. The thermomechanical coupling model produces outputs such as the rules of bulge deformation. Moreover, the three-dimensional model has been compared with a two-dimensional model to discuss the differences between the two models in calculating the bulge deformation. The results show that the platform zone exists in the wide side of the slab and the bulge deformation is affected strongly by the ratio of width-to-thickness. The indications are also that the difference of the bulge deformation for the two modeling ways is little when the ratio of width-to-thickness is larger than six.
Axial turbomachine modelling with a quasi-2-D approach. Application to gas cooled reactor transients
International Nuclear Information System (INIS)
Nicolas Tauveron; Manuel Saez; Pascal Ferrand; Francis Leboeuf
2005-01-01
Full text of publication follows: In the frame of the international forum GenIV, CEA has selected two innovative concepts of High Temperature gas cooled Reactor. The first has a fast neutron spectrum, a robust refractory fuel and a direct cycle conversion. The second is a very high temperature reactor with a thermal neutron spectrum. Both concepts make use of technology derived from High Temperature Gas Reactor. Thermal hydraulic performances are a key issue for the design. For transient conditions and decay heat removal situations, the thermal hydraulic performance must remain as high as possible. In this context, all the transient situations, the incidental and accidental scenarios must be evaluated by a validated system code able to correctly describe, in particular, the thermal-hydraulics of the whole plant. With this type of reactor a special emphasis must be laid on turbomachinery modelling. A first step was to compute a HTGR concept using the steady-state characteristics of each element of the turbomachinery with the computer code CATHARE. In a hypothetical transient event (a 10 inches cold duct break of primary loop which causes a rapid depressurization and a decrease of the core mass flow rate) the results seem of great interest (as a forced convection was maintained by the compressors during the entire transient) but not sufficiently justified in the frame of 0D modelling of turbomachinery. A more precise description of the turbomachinery has been developed based on a quasi-two dimensional approach. Although this type of flow analysis is a simplification of a complex three dimensional system, it is able to describe the behaviour of a compressor or a turbine with a better understanding than the models based on component characteristics. This approach consists in the solving of 2D radially averaged Navier-Stokes equations with the hypothesis of circumferentially uniform flow. The assumption of quasi-steady behaviour is made: source terms for the lift and
Coupled 1-D sewer and street networks and 2-D flooding model to rapidly evaluate surface inundation
Kao, Hong-Ming; Hsu, Hao-Ming
2017-04-01
Flash floods have occurred frequently in the urban areas around the world and cause the infrastructure and people living to expose continuously in the high risk level of pluvial flooding. According to historical surveys, the major reasons of severe surface inundations in the urban areas can be attributed to heavy rainfall in the short time and/or drainage system failure. In order to obtain real-time flood forecasting with high accuracy and less uncertainty, an appropriate system for predicting floods is necessary. For the reason, this study coupled 1-D sewer and street networks and 2-D flooding model as an operational modelling system for rapidly evaluating surface inundation. The proposed system is constructed by three significant components: (1) all the rainfall-runoff of a sub-catchment collected via gullies is simulated by the RUNOFF module of the Storm Water Management Model (SWMM); (2) and directly drained to the 1-D sewer and street networks via manholes as inflow discharges to conduct flow routing by using the EXTRAN module of SWMM; (3) after the 1-D simulations, the surcharges from manholes are considered as point sources in 2-D overland flow simulations that are executed by the WASH123D model. It can thus be used for urban flood modelling that reflects the rainfall-runoff processes, and the dynamic flow interactions between the storm sewer system and the ground surface in urban areas. In the present study, we adopted the Huwei Science and Technology Park, located in the south-western part of Taiwan, as the demonstration area because of its high industrial values. The region has an area about 1 km2 with approximately 1 km in both length and width. It is as isolated urban drainage area in which there is a complete sewer system that collects the runoff and drains to the detention pond. Based on the simulated results, the proposed modelling system was found that the simulated floods fit to the survey records because the physical rainfall-runoff phenomena in
Goteti, Rajesh; Agar, Susan M.; Brown, John P.; Ball, Philip; Zuhlke, Rainer
2017-04-01
Mechanical stratification in LES (Layered Evaporate Sequences) can have a distinct impact on structural and depositional styles in rifted margin salt tectonics. The bulk mechanical response of an LES under geological loading is dependent, among other factors, on the relative proportions of salt and sediment, salt mobility and sedimentation rate. To assess the interactions among the aforementioned factors in a physically consistent manner, we present 2D, large-strain finite element models of an LES salt minibasin and diapirs. Loading from the deposition of alternating salt and sediment layers (i.e., LES), gravity and a prescribed geothermal gradient provide the driving force for halokinesis in the models. To accurately capture the mechanical impact of stratification within the modeled LES, salt is assigned a temperature-dependent visco-plastic rheology, whereas the sediments are assigned a non-associative cap-plasticity model that supports both compaction and shear localization. Perturbations in the initial salt-sediment interface are used to initiate the salt diapirs. Model results suggest that active diapirism in the basal halite layer initiates when the pressure at the base of the incipient salt diapir exceeds that beneath the minibasin. Vertical growth of the diapir is also accompanied by its lateral expansion at higher structural levels where it preferentially intrudes the adjacent pre- and syn-kinematic salt layers. This pressure pumping of deeper salt into shallow salt layers, can result in rapid thickness changes between successive sediment layers within the LES. Caution needs to be exercised as such thickness changes observed in seismic images may not be entirely due to the shifting of depocenters but also due to the lateral pumping of salt within the LES. The presence of salt layers at multiple structural levels decouples the deformation between successive clastic layers resulting in disharmomic folding with contrasting strain histories in the sedimentary
Using 2D image composition to model and evaluate soldier camouflage in the visible wavelengths
CSIR Research Space (South Africa)
Duvenhage B
2011-06-01
Full Text Available . The digital pattern is then re-coloured with the measured CIELAB colours. We use Photoshop to convert the CIELAB camouflage pattern to the Red, Green and Blue (RGB) colour space (under the D50 standard daylight illuminant) for use by the 2D image...
• LTV can be used to characterize free phase PCE architecture in 2-D flow chambers without using a dye. • Results to date suggest that error in PCE detection using LTV can be less than 10% if the imaging system is optimized. • Mass balance calculations show a maximum error of 9...
Directory of Open Access Journals (Sweden)
F. Tornabene
2016-01-01
Full Text Available The cylindrical bending condition for structural models is very common in the literature because it allows an incisive and simple verification of the proposed plate and shell models. In the present paper, 2D numerical approaches (the Generalized Differential Quadrature (GDQ and the finite element (FE methods are compared with an exact 3D shell solution in the case of free vibrations of functionally graded material (FGM plates and shells. The first 18 vibration modes carried out through the 3D exact model are compared with the frequencies obtained via the 2D numerical models. All the 18 frequencies obtained via the 3D exact model are computed when the structures have simply supported boundary conditions for all the edges. If the same boundary conditions are used in the 2D numerical models, some modes are missed. Some of these missed modes can be obtained modifying the boundary conditions imposing free edges through the direction perpendicular to the direction of cylindrical bending. However, some modes cannot be calculated via the 2D numerical models even when the boundary conditions are modified because the cylindrical bending requirements cannot be imposed for numerical solutions in the curvilinear edges by definition. These features are investigated in the present paper for different geometries (plates, cylinders, and cylindrical shells, types of FGM law, lamination sequences, and thickness ratios.
A computational approach for coupled 1D and 2D/3D CFD modelling of pulse Tube cryocoolers
Fang, T.; Spoor, P. S.; Ghiaasiaan, S. M.
2017-12-01
The physics behind Stirling-type cryocoolers are complicated. One dimensional (1D) simulation tools offer limited details and accuracy, in particular for cryocoolers that have non-linear configurations. Multi-dimensional Computational Fluid Dynamic (CFD) methods are useful but are computationally expensive in simulating cyrocooler systems in their entirety. In view of the fact that some components of a cryocooler, e.g., inertance tubes and compliance tanks, can be modelled as 1D components with little loss of critical information, a 1D-2D/3D coupled model was developed. Accordingly, one-dimensional – like components are represented by specifically developed routines. These routines can be coupled to CFD codes and provide boundary conditions for 2D/3D CFD simulations. The developed coupled model, while preserving sufficient flow field details, is two orders of magnitude faster than equivalent 2D/3D CFD models. The predictions show good agreement with experimental data and 2D/3D CFD model.
Energy Technology Data Exchange (ETDEWEB)
Nordeck, Shaun M. [University of Texas Southwestern Medical College, Dallas, TX (United States); University of Texas Southwestern Medical Center, Musculoskeletal Radiology, Dallas, TX (United States); Koerper, Conrad E.; Adler, Aaron [University of Texas Southwestern Medical College, Dallas, TX (United States); Malhotra, Vidur; Xi, Yin [University of Texas Southwestern Medical Center, Musculoskeletal Radiology, Dallas, TX (United States); Liu, George T. [University of Texas Southwestern Medical Center, Orthopaedic Surgery, Dallas, TX (United States); Chhabra, Avneesh [University of Texas Southwestern Medical Center, Musculoskeletal Radiology, Dallas, TX (United States); University of Texas Southwestern Medical Center, Orthopaedic Surgery, Dallas, TX (United States)
2017-05-15
The purpose of this work is to simulate radiographs from isotropic 3D MRI data, compare relationship of angle and joint space measurements on simulated radiographs with corresponding 2D MRIs and real radiographs (XR), and compare measurement times among the three modalities. Twenty-four consecutive ankles were included, eight males and 16 females, with a mean age of 46 years. Segmented joint models simulating radiographs were created from 3D MRI data sets. Three readers independently performed blinded angle and joint space measurements on the models, corresponding 2D MRIs, and XRs at two time points. Linear mixed models and the intraclass correlation coefficient (ICC) was ascertained, with p values less than 0.05 considered significant. Simulated radiograph models were successfully created in all cases. Good agreement (ICC > 0.65) was noted among all readers across all modalities and among most measurements. Absolute measurement values differed between modalities. Measurement time was significantly greater (p < 0.05) on 2D versus simulated radiographs for most measurements and on XR versus simulated radiographs (p < 0.05) for nearly half the measurements. Simulated radiographs can be successfully generated from 3D MRI data; however, measurements differ. Good inter-reader and moderate-to-good intra-reader reliability was observed and measurements obtained on simulated radiograph models took significantly less time compared to measurements with 2D and generally less time than XR. (orig.)
Modeling Turkey National 2D Geo-Data Model as a CityGML Application Domain Extension in UML
Directory of Open Access Journals (Sweden)
Serpil Ates Aydar
2016-12-01
Full Text Available This paper presents the generation of the 3D national geo-data model of Turkey, which is compatible with the international OGC CityGML Encoding Standard. We prepare an ADE named CityGML-TRKBIS that is produced by extending existing thematic modules of CityGML according to TRKBIS needs. All thematic data groups in TRKBIS geo-data model have been remodeled in order to generate the national large scale 3D geodata model for Turkey. Within the concept of reference model-driven framework for modelling CityGML ADEs in UML, the first step is conceptual mapping between CityGML and national information model. To test all stages of the framework for Urban GIS Turkey, Building data theme is mapped with CityGML-Building thematic model. All classes, attributes, code lists and code list values of the TRKBIS is tried to be mapped with related CityGML concept. New classes, attributes and code list values that will be added to CityGML Building model are determined based on this conceptual mapping. Finally the new model for CityGML-TRKBIS.BI is established in UML with subclassing of the related CityGML classes. This study provides new insights into 3D applications in Turkey. The generated 3D geo-data model for building thematic class will be used as a common exchange format that meets 2D, 2.5D and 3D implementation needs at national level.
Liu, Wu; Ma, Xiangyu; Yan, Huagang; Chen, Zhe; Nath, Ravinder; Li, Haiyun
2017-05-01
Many real-time imaging techniques have been developed to localize a target in 3D space or in a 2D beam’s eye view (BEV) plane for intrafraction motion tracking in radiation therapy. With tracking system latency, the 3D-modeled method is expected to be more accurate even in terms of 2D BEV tracking error. No quantitative analysis, however, has been reported. In this study, we simulated co-planar arc deliveries using respiratory motion data acquired from 42 patients to quantitatively compare the accuracy between 2D BEV and 3D-modeled tracking in arc therapy and to determine whether 3D information is needed for motion tracking. We used our previously developed low kV dose adaptive MV-kV imaging and motion compensation framework as a representative of 3D-modeled methods. It optimizes the balance between additional kV imaging dose and 3D tracking accuracy and solves the MLC blockage issue. With simulated Gaussian marker detection errors (zero mean and 0.39 mm standard deviation) and ~155/310/460 ms tracking system latencies, the mean percentage of time that the target moved >2 mm from the predicted 2D BEV position are 1.1%/4.0%/7.8% and 1.3%/5.8%/11.6% for the 3D-modeled and 2D-only tracking, respectively. The corresponding average BEV RMS errors are 0.67/0.90/1.13 mm and 0.79/1.10/1.37 mm. Compared to the 2D method, the 3D method reduced the average RMS unresolved motion along the beam direction from ~3 mm to ~1 mm, resulting in on average only <1% dosimetric advantage in the depth direction. Only for a small fraction of the patients, when tracking latency is long, the 3D-modeled method showed significant improvement of BEV tracking accuracy, indicating potential dosimetric advantage. However, if the tracking latency is short (~150 ms or less), those improvements are limited. Therefore, 2D BEV tracking has sufficient targeting accuracy for most clinical cases. The 3D technique is, however, still important in solving the MLC blockage problem
Information on the gauge principle from an N=1/2, D=2 supersymmetric model
International Nuclear Information System (INIS)
Dias, S.A.; Doria, R.M.; Valle, J.L.M.
1988-01-01
The gauge principle does not only work to generate interactions. It potentially yields an abundance of gauge-potential fields transforming under the same local symmetry group. In order to show evidences of this property this work gauge-covariantizes an N = 1/2, D = 2 supersymmetric theory. Then, by relaxing the so-called conventional constraint, a second gauge-potential field naturally emerges. (author) [pt
DEFF Research Database (Denmark)
Rasmussen, Filip Salling; Sonne, Mads Rostgaard; Larsen, Martin
In the present study, a two-dimensional (2D) transient Eulerian thermo-chemical analysis of a carbon fibre epoxy thermosetting Resin Injection Pultrusion (RIP) process is carried out. The numerical model is implemented using the well known unconditionally stable Alternating Direction Implicit (ADI...... inside the composite profile are validated by comparison with experimental measurements and good agreement is found....
MOD_FreeSurf2D: a Surface Fluid Flow Simulation Model for Rivers, Streams, and Shallow Estuaries
Martin, N.; Gorelick, S. M.
2003-12-01
The MOD_FreeSurf2D, Modular Free Surface Flow in Two-Dimensions, computer model simulates free surface fluid flow in streams, rivers, and shallow estuaries under the assumptions of a well-mixed water column, a small water depth to width ratio, and a hydrostatic pressure distribution. The dependent variables in the model are free surface elevation, which provides total water depth, and fluid velocity. Primary advantages of MOD_FreeSurf2D relative to other two-dimensional models are a stable and computationally efficient numerical representation and a transparent representation of wetting and drying of the simulation domain. MOD_FreeSurf2D approximates the depth-averaged, shallow water equations with a finite volume, semi-implicit, semi-Lagrangian numerical representation similar to the TRIM method (Casulli, 1990; Casulli and Cheng, 1992; Casulli, 1999). The semi-implicit, semi-Lagrangian approach is computationally efficient because time steps can exceed the Courant-Friedrich-Lewy (CFL) stability criterion without significant accuracy degradation (Robert, 1982; Casulli, 1990). The rectangular, Arakawa C-grid, finite-volume layout allows flooding and drying in response to changing flow conditions without prior channel specification or closed boundary specification. Open boundary conditions available in MOD_FreeSurf2D are specified flux, specified total water depth, specified velocity, radiation free surface, and radiation velocity. MOD_FreeSurf2D requires initial topography, undisturbed water depth, and Manning's roughness coefficient. MOD_FreeSurf2D simulated results are shown to converge to the semi-empirical solution for a simple straight channel case. Two applications demonstrate the accuracy of MOD_FreeSurf2D. The first application is the evolution of water depth in the dambreak-style flume experiment of Bellos et al. (1992). In this case, MOD_FreeSurf2D accurately simulates the changing water depth in the flume during the experiment and models the wetting of
Comparison between a 1D and a 2D numerical model of an active magnetic regenerative refrigerator
International Nuclear Information System (INIS)
Petersen, Thomas Frank; Bahl, Christian R H; Pryds, Nini; Smith, Anders; Engelbrecht, Kurt; Elmegaard, Brian
2008-01-01
The active magnetic regenerator (AMR) refrigeration system represents an environmentally attractive alternative to vapour-compression refrigeration. This paper compares the results of two numerical AMR models: (1) a 1D finite difference model and (2) a 2D finite element model. Both models simulate a reciprocating AMR and can determine the cyclical steady-state temperature profile of the system as well as performance parameters such as the refrigeration capacity, the work input and the coefficient of performance (COP). The models are used to analyse an AMR with a regenerator made of flat parallel plates of gadolinium operating in the presence of a 1 T magnetic field. The results are used to discuss under which circumstances a 1D model is insufficient and a 2D model is necessary. The results indicate that when the temperature gradients in the AMR perpendicular to the flow are small a 1D model obtains accurate results of overall results such as the refrigeration capacity but that a 2D model is required for a detailed analysis of the phenomena occurring inside the AMR
Synaptic Deficits at Neuromuscular Junctions in Two Mouse Models of Charcot-Marie-Tooth Type 2d.
Spaulding, Emily L; Sleigh, James N; Morelli, Kathryn H; Pinter, Martin J; Burgess, Robert W; Seburn, Kevin L
2016-03-16
Patients with Charcot-Marie-Tooth Type 2D (CMT2D), caused by dominant mutations in Glycl tRNA synthetase (GARS), present with progressive weakness, consistently in the hands, but often in the feet also. Electromyography shows denervation, and patients often report that early symptoms include cramps brought on by cold or exertion. Based on reported clinical observations, and studies of mouse models of CMT2D, we sought to determine whether weakened synaptic transmission at the neuromuscular junction (NMJ) is an aspect of CMT2D. Quantal analysis of NMJs in two different mouse models of CMT2D (Gars(P278KY), Gars(C201R)), found synaptic deficits that correlated with disease severity and progressed with age. Results of voltage-clamp studies revealed presynaptic defects characterized by: (1) decreased frequency of spontaneous release without any change in quantal amplitude (miniature endplate current), (2) reduced amplitude of evoked release (endplate current) and quantal content, (3) age-dependent changes in the extent of depression in response to repetitive stimulation, and (4) release failures at some NMJs with high-frequency, long-duration stimulation. Drugs that modify synaptic efficacy were tested to see whether neuromuscular performance improved. The presynaptic action of 3,4 diaminopyridine was not beneficial, whereas postsynaptic-acting physostigmine did improve performance. Smaller mutant NMJs with correspondingly fewer vesicles and partial denervation that eliminates some release sites also contribute to the reduction of release at a proportion of mutant NMJs. Together, these voltage-clamp data suggest that a number of release processes, while essentially intact, likely operate suboptimally at most NMJs of CMT2D mice. We have uncovered a previously unrecognized aspect of axonal Charcot-Marie-Tooth disease in mouse models of CMT2D. Synaptic dysfunction contributes to impaired neuromuscular performance and disease progression. This suggests that drugs which
Statistical coronary motion models for 2D + t/3D registration of X-ray coronary angiography and CTA
DEFF Research Database (Denmark)
Baka, N.; Metz, C. T.; Schultz, C.
2013-01-01
Accurate alignment of intra-operative X-ray coronary angiography (XA) and pre-operative cardiac CT angiography (CTA) may improve procedural success rates of minimally invasive coronary interventions for patients with chronic total occlusions. It was previously shown that incorporating patient...... motion models to provide constraints for the 2D+t/3D registration. We propose a methodology for building statistical motion models of the coronary arteries from a training population of 4D CTA datasets. We compare the 2D+t/3D registration performance of the proposed statistical models with other motion...... estimates, including the patient specific motion extracted from 4D CTA, the mean motion of a population, the predicted motion based on the cardiac shape. The coronary motion models, constructed on a training set of 150 patients, had a generalization accuracy of 1mm root mean square point-to-point distance...
Non-stationary covariance function modelling in 2D least-squares collocation
Darbeheshti, N.; Featherstone, W. E.
2009-06-01
Standard least-squares collocation (LSC) assumes 2D stationarity and 3D isotropy, and relies on a covariance function to account for spatial dependence in the observed data. However, the assumption that the spatial dependence is constant throughout the region of interest may sometimes be violated. Assuming a stationary covariance structure can result in over-smoothing of, e.g., the gravity field in mountains and under-smoothing in great plains. We introduce the kernel convolution method from spatial statistics for non-stationary covariance structures, and demonstrate its advantage for dealing with non-stationarity in geodetic data. We then compared stationary and non- stationary covariance functions in 2D LSC to the empirical example of gravity anomaly interpolation near the Darling Fault, Western Australia, where the field is anisotropic and non-stationary. The results with non-stationary covariance functions are better than standard LSC in terms of formal errors and cross-validation against data not used in the interpolation, demonstrating that the use of non-stationary covariance functions can improve upon standard (stationary) LSC.
FireStem2D A two-dimensional heat transfer model for simulating tree stem injury in fires
Efthalia K. Chatziefstratiou; Gil Bohrer; Anthony S. Bova; Ravishankar Subramanian; Renato P.M. Frasson; Amy Scherzer; Bret W. Butler; Matthew B. Dickinson
2013-01-01
FireStem2D, a software tool for predicting tree stem heating and injury in forest fires, is a physically-based, two-dimensional model of stem thermodynamics that results from heating at the bark surface. It builds on an earlier one-dimensional model (FireStem) and provides improved capabilities for predicting fire-induced mortality and injury before a fire occurs by...
Blitz, Celine; Komatitsch, Dimitri; Lognonné, Philippe; Martin, Roland; Le Goff, Nicolas
The understanding of the interior structure of Near Earth Objects (NEOs) is a fundamental issue to determine their evolution and origin, and also, to design possible mitigation techniques (Walker and Huebner, 2004). Indeed, if an oncoming Potentially Hazardous Object (PHO) were to threaten the Earth, numerous methods are suggested to prevent it from colliding our planet. Such mitigation techniques may involve nuclear explosives on or below the object surface, impact by a projectile, or concentration of solar energy using giant mirrors (Holsapple, 2004). The energy needed in such mitigation techniques highly depends on the porosity of the hazardous threatening object (asteroid or comet), as suggested by Holsapple, 2004. Thus, for a given source, the seismic response of a coherent homogeneous asteroid should be very different from the seismic response of a fractured or rubble-pile asteroid. To assess this hypothesis, we performed numerical simulations of wave propagation in different interior models of the Near Earth Asteroid 433 Eros. The simulations of wave propagation required a shape model of asteroid Eros, kindly provided by A. Cheng and O. Barnouin-Jha (personal communication). A cross-section along the longest axis has been chosen to define our 2D geometrical model, and we study two models of the interior: a homogeneous one, and a complex one characterized by fault networks below the main crosscut craters, and covered by a regolith layer of thickness ranging from 50 m to 150 m. To perform the numerical simulations we use the spectral-element method, which solves the variational weak form of the seismic wave equation (Komatitsch and Tromp, 1999) on the meshes of the 2D models of asteroid Eros. The homogeneous model is composed of an elastic material characterized by a pressure wave velocity Vp = 3000 m.s-1 , a shear wave velocity Vs = 1700 m.s-1 and a density of 2700 kg.m-3 . The fractured model possesses the same characteristics except for the presence of
Sherwin, Catherine M. T.; Saldaña, Shannon N.; Bies, Robert R.; Aman, Michael G.; Vinks, Alexander A.
2012-01-01
AIM The study aims were to characterize risperidone and (±)-9-hydroxyrisperidone pharmacokinetic variability in children and adolescents and to evaluate covariate effects on pharmacokinetic parameters. METHODS Steady-state samples were drawn at pre-dose, 1, 2, 4, and 7 hours post-dose; CYP2D6 genotypes were available for 28 subjects. A non-linear mixed-effects model (NONMEM®) modeled the pharmacokinetics of risperidone and (±)-9-hydroxyrisperidone; covariates included age, weight, sex, and CYP2D6 phenotype. The model included 497 observations [risperidone (n=163), (+) and (−) 9-hydroxyrisperidone (n=334)] from 45 subjects aged 3–18.3 (mean 9.6±3.7) years, weighing 16.8–110 (43±20.2) kg. RESULTS A one-compartment mixture model described risperidone and (±)-9-hydroxyrisperidone clearances for three CYP2D6 metabolizer subpopulations: extensive (EM), intermediate (IM), and poor (PM). Weight significantly affected (±)-9-hydroxyrisperidone clearance. Clearance estimates in the mixture model were PM 9.38 L/h, IM 29.2 L/h, and EM 37.4 L/h. CONCLUSION Active moiety [risperidone plus (±)-9-hydroxyrisperidone] pharmacokinetic variability and the covariate effects were better explained with addition of metabolite pharmacokinetic parameters. This model may aid development of individualized risperidone dosing regimens in children and adolescents. PMID:22929407
Ivy, D. J.; Rigby, M. L.; Prinn, R. G.; Muhle, J.; Weiss, R. F.
2009-12-01
We present optimized annual global emissions from 1973-2008 of nitrogen trifluoride (NF3), a powerful greenhouse gas which is not currently regulated by the Kyoto Protocol. In the past few decades, NF3 production has dramatically increased due to its usage in the semiconductor industry. Emissions were estimated through the 'pulse-method' discrete Kalman filter using both a simple, flexible 2-D 12-box model used in the Advanced Global Atmospheric Gases Experiment (AGAGE) network and the Model for Ozone and Related Tracers (MOZART v4.5), a full 3-D atmospheric chemistry model. No official audited reports of industrial NF3 emissions are available, and with limited information on production, a priori emissions were estimated using both a bottom-up and top-down approach with two different spatial patterns based on semiconductor perfluorocarbon (PFC) emissions from the Emission Database for Global Atmospheric Research (EDGAR v3.2) and Semiconductor Industry Association sales information. Both spatial patterns used in the models gave consistent results, showing the robustness of the estimated global emissions. Differences between estimates using the 2-D and 3-D models can be attributed to transport rates and resolution differences. Additionally, new NF3 industry production and market information is presented. Emission estimates from both the 2-D and 3-D models suggest that either the assumed industry release rate of NF3 or industry production information is still underestimated.
Nordeck, Shaun M; Koerper, Conrad E; Adler, Aaron; Malhotra, Vidur; Xi, Yin; Liu, George T; Chhabra, Avneesh
2017-05-01
The purpose of this work is to simulate radiographs from isotropic 3D MRI data, compare relationship of angle and joint space measurements on simulated radiographs with corresponding 2D MRIs and real radiographs (XR), and compare measurement times among the three modalities. Twenty-four consecutive ankles were included, eight males and 16 females, with a mean age of 46 years. Segmented joint models simulating radiographs were created from 3D MRI data sets. Three readers independently performed blinded angle and joint space measurements on the models, corresponding 2D MRIs, and XRs at two time points. Linear mixed models and the intraclass correlation coefficient (ICC) was ascertained, with p values less than 0.05 considered significant. Simulated radiograph models were successfully created in all cases. Good agreement (ICC > 0.65) was noted among all readers across all modalities and among most measurements. Absolute measurement values differed between modalities. Measurement time was significantly greater (p 3D MRI data; however, measurements differ. Good inter-reader and moderate-to-good intra-reader reliability was observed and measurements obtained on simulated radiograph models took significantly less time compared to measurements with 2D and generally less time than XR.
A 2D hydrodynamic-sedimentological model for gravel-bed rivers. Part I: theory and validation
Gabriel Kaless; Mario A. Lenzi; Luca Mao
2013-01-01
This paper presents a novel 2D-depth average model especially developed for gravel-bed rivers, named Lican-Leufú (Lican=pebble and Leufu=river, in Mapuche’s language, the native inhabitants of Central Patagonia, Argentina). The model consists of three components: a hydrodynamic, a sedimentological, and a morphological model. The flow of water is described by the depth-averaged Reynolds equations for unsteady, free-surface, shallow water flows. It includes the standard k-e model for turbulence...
DEFF Research Database (Denmark)
Löwe, Roland; Davidsen, Steffen; Thrysøe, Cecilie
the 1D network model. The simplifications lead to an underestimation of flooded area because interaction points between network and surface are removed and because water is transported downstream faster. These effects can be mitigated by maintaining nodes in flood-prone areas in the simplification......We present an algorithm for automated simplification of 1D pipe network models. The impact of the simplifications on the flooding simulated by coupled 1D-2D models is evaluated in an Australian case study. Significant reductions of the simulation time of the coupled model are achieved by reducing...
SU-E-T-05: A 2D EPID Transit Dosimetry Model Based On An Empirical Quadratic Formalism
International Nuclear Information System (INIS)
Tan, Y; Metwaly, M; Glegg, M; Baggarley, S; Elliott, A
2014-01-01
Purpose: To describe a 2D electronic portal imaging device (EPID) transit dosimetry model, based on an empirical quadratic formalism, that can predict either EPID or in-phantom dose distribution for comparisons with EPID captured image or treatment planning system (TPS) dose respectively. Methods: A quadratic equation can be used to relate the reduction in intensity of an exit beam to the equivalent path length of the attenuator. The calibration involved deriving coefficients from a set of dose planes measured for homogeneous phantoms with known thicknesses under reference conditions. In this study, calibration dose planes were measured with EPID and ionisation chamber (IC) in water for the same reference beam (6MV, 100mu, 20×20cm 2 ) and set of thicknesses (0–30cm). Since the same calibration conditions were used, the EPID and IC measurements can be related through the quadratic equation. Consequently, EPID transit dose can be predicted from TPS exported dose planes and in-phantom dose can be predicted using EPID distribution captured during treatment as an input. The model was tested with 4 open fields, 6 wedge fields, and 7 IMRT fields on homogeneous and heterogeneous phantoms. Comparisons were done using 2D absolute gamma (3%/3mm) and results were validated against measurements with a commercial 2D array device. Results: The gamma pass rates for comparisons between EPID measured and predicted ranged from 93.6% to 100.0% for all fields and phantoms tested. Results from this study agreed with 2D array measurements to within 3.1%. Meanwhile, comparisons in-phantom between TPS computed and predicted ranged from 91.6% to 100.0%. Validation with 2D array device was not possible for inphantom comparisons. Conclusion: A 2D EPID transit dosimetry model for treatment verification was described and proven to be accurate. The model has the advantage of being generic and allows comparisons at the EPID plane as well as multiple planes in-phantom
Bone and joint modeling from 3D knee MRI: feasibility and comparison with radiographs and 2D MRI.
Wadhwa, Vibhor; Malhotra, Vidur; Xi, Yin; Nordeck, Shaun; Coyner, Katherine; Chhabra, Avneesh
2016-01-01
The purpose was to evaluate feasibility of bone and joint segmentations from three-dimensional magnetic resonance imaging (3D MRI). Segmented joint models from 3D MRI data set were obtained for 42 patients. Blinded angular and joint space measurements were performed on 3D MRI model, two-dimensional (2D) MRI, and radiography (XR). Medial joint space was similar on both XR and 3D MRI (P=.3). The XR measurements were statistically different but closer to 3D MRI for lateral patellar tilt angle, patellar tendon length, and lateral knee joint space, whereas 2D MRI measurements were closer to XR in terms of trochlear depth, sulcal angle, and patellar length. 3D bone and joint segmentations are feasible from isotropic MRI data sets. Copyright © 2016 Elsevier Inc. All rights reserved.
A new approach for assimilation of 2D radar precipitation in a high-resolution NWP model
DEFF Research Database (Denmark)
Korsholm, Ulrik Smith; Petersen, Claus; Sass, Bent Hansen
2015-01-01
A new approach for assimilation of 2D precipitation in numerical weather prediction models is presented and tested in a case with convective, heavy precipitation. In the scheme a nudging term is added to the horizontal velocity divergence tendency equation. In case of underproduction of precipita...... precipitation rates. In this meteorological case, the usage of the nudging procedure has been shown to improve the prediction of heavy precipitation substantially....
Directory of Open Access Journals (Sweden)
G. Zodiatis
1996-11-01
Full Text Available A statistical technique for image processing, the maximum cross correlation (MCC method, was utilized on sequences of NOAA-AVHRR thermal data in order to explore the surface advective current dynamics at the discharge region of the Hellespont in the North Aegean Sea. A 2D numerical flow model was also used in order to simulate the barotropic flow pattern of the surface water layer. The model was forced with diurnal wind fields obtained for the same period as the satellite infrared images. The currents (magnitude and direction derived from the two methods compare satisfactorily despite the fact that some model simplifications were made.
Hidalgo, D; Sacco, A; Hernández, S; Tommasi, T
2015-11-01
A mixed microbial population naturally presents in seawater was used as active anodic biofilm of two Microbial Fuel Cells (MFCs), employing either a 2D commercial carbon felt or 3D carbon-coated Berl saddles as anode electrodes, with the aim to compare their electrochemical behavior under continuous operation. After an initial increase of the maximum power density, the felt-based cell reduced its performance at 5 months (from 7 to 4 μW cm(-2)), while the saddle-based MFC exceeds 9 μW cm(-2) (after 2 months) and maintained such performance for all the tests. Electrochemical impedance spectroscopy was used to identify the MFCs controlling losses and indicates that the mass-transport limitations at the biofilm-electrolyte interface have the main contribution (>95%) to their internal resistance. The activation resistance was one order of magnitude lower with the Berl saddles than with carbon felt, suggesting an enhanced charge-transfer in the high surface-area 3D electrode, due to an increase in bacteria population growth. Copyright © 2015 Elsevier Ltd. All rights reserved.
Couple stress theory of curved rods. 2-D, high order, Timoshenko’s and Euler-Bernoulli models
Directory of Open Access Journals (Sweden)
Zozulya V.V.
2017-01-01
Full Text Available New models for plane curved rods based on linear couple stress theory of elasticity have been developed.2-D theory is developed from general 2-D equations of linear couple stress elasticity using a special curvilinear system of coordinates related to the middle line of the rod as well as special hypothesis based on assumptions that take into account the fact that the rod is thin. High order theory is based on the expansion of the equations of the theory of elasticity into Fourier series in terms of Legendre polynomials. First, stress and strain tensors, vectors of displacements and rotation along with body forces have been expanded into Fourier series in terms of Legendre polynomials with respect to a thickness coordinate.Thereby, all equations of elasticity including Hooke’s law have been transformed to the corresponding equations for Fourier coefficients. Then, in the same way as in the theory of elasticity, a system of differential equations in terms of displacements and boundary conditions for Fourier coefficients have been obtained. Timoshenko’s and Euler-Bernoulli theories are based on the classical hypothesis and the 2-D equations of linear couple stress theory of elasticity in a special curvilinear system. The obtained equations can be used to calculate stress-strain and to model thin walled structures in macro, micro and nano scales when taking into account couple stress and rotation effects.
Nonlocal theory of curved rods. 2-D, high order, Timoshenko’s and Euler-Bernoulli models
Directory of Open Access Journals (Sweden)
Zozulya V.V.
2017-09-01
Full Text Available New models for plane curved rods based on linear nonlocal theory of elasticity have been developed. The 2-D theory is developed from general 2-D equations of linear nonlocal elasticity using a special curvilinear system of coordinates related to the middle line of the rod along with special hypothesis based on assumptions that take into account the fact that the rod is thin. High order theory is based on the expansion of the equations of the theory of elasticity into Fourier series in terms of Legendre polynomials. First, stress and strain tensors, vectors of displacements and body forces have been expanded into Fourier series in terms of Legendre polynomials with respect to a thickness coordinate. Thereby, all equations of elasticity including nonlocal constitutive relations have been transformed to the corresponding equations for Fourier coefficients. Then, in the same way as in the theory of local elasticity, a system of differential equations in terms of displacements for Fourier coefficients has been obtained. First and second order approximations have been considered in detail. Timoshenko’s and Euler-Bernoulli theories are based on the classical hypothesis and the 2-D equations of linear nonlocal theory of elasticity which are considered in a special curvilinear system of coordinates related to the middle line of the rod. The obtained equations can be used to calculate stress-strain and to model thin walled structures in micro- and nanoscales when taking into account size dependent and nonlocal effects.
Itzá Balam, Reymundo; Iturrarán-Viveros, Ursula; Parra, Jorge O.
2018-03-01
Two main stages of seismic modeling are geological model building and numerical computation of seismic response for the model. The quality of the computed seismic response is partly related to the type of model that is built. Therefore, the model building approaches become as important as seismic forward numerical methods. For this purpose, three petrophysical facies (sands, shales and limestones) are extracted from reflection seismic data and some seismic attributes via the clustering method called Self-Organizing Maps (SOM), which, in this context, serves as a geological model building tool. This model with all its properties is the input to the Optimal Implicit Staggered Finite Difference (OISFD) algorithm to create synthetic seismograms for poroelastic, poroacoustic and elastic media. The results show a good agreement between observed and 2-D synthetic seismograms. This demonstrates that the SOM classification method enables us to extract facies from seismic data and allows us to integrate the lithology at the borehole scale with the 2-D seismic data.
International Nuclear Information System (INIS)
Huang, Yuan-Ruei; Shih, Jun-Ming; Chang, Kang-Wei; Huang, Chieh; Wu, Yu-Lung; Chen, Chia-Chieh
2012-01-01
Purpose: [ 123 I]Epidepride is a radio-tracer with very high affinity for dopamine D 2 /D 3 receptors in brain. The importance of alteration in dopamine D 2 /D 3 receptor binding condition has been wildly verified in schizophrenia. In the present study we set up a rat schizophrenia model by chronic injection of a non-competitive NMDA receptor antagonist, MK-801, to examine if [ 123 I]epidepride could be used to evaluate the alterations of dopamine D 2 /D 3 receptor binding condition in specific brain regions. Method: Rats were given repeated injection of MK-801 (dissolved in saline, 0.3 mg/kg) or saline for 1 month. Afterwards, total distance traveled (cm) and social interaction changes were recorded. Radiochemical purity of [ 123 I]epidepride was analyzed by Radio-Thin-Layer Chromatography (chloroform: methanol, 9:1, v/v) and [ 123 I]epidepride neuroimages were obtained by ex vivo autoradiography and small animal SPECT/CT. Data obtained were then analyzed to determine the changes of specific binding ratio. Result: Chronic MK-801 treatment for a month caused significantly increased local motor activity and induced an inhibition of social interaction. As shown in [ 123 I]epidepride ex vivo autoradiographs, MK-801 induced a decrease of specific binding ratio in the striatum (24.01%), hypothalamus (35.43%), midbrain (41.73%) and substantia nigra (37.93%). In addition, [ 123 I]epidepride small animal SPECT/CT neuroimaging was performed in the striatum and midbrain. There were statistically significant decreases in specific binding ratio in both the striatum (P 123 I]epidepride is a useful radio-tracer to reveal the alterations of dopamine D 2 /D 3 receptor binding in a rat schizophrenia model and is also helpful to evaluate therapeutic effects of schizophrenia in the future.
Natural disease history of mouse models for limb girdle muscular dystrophy types 2D and 2F
Putker, K.; Tanganyika-de Winter, C. L.; Boertje-van der Meulen, J. W.; van Vliet, L.; Overzier, M.; Plomp, J. J.; Aartsma-Rus, A.; van Putten, M.
2017-01-01
Limb-girdle muscular dystrophy types 2D and 2F (LGMD 2D and 2F) are autosomal recessive disorders caused by mutations in the alpha- and delta sarcoglycan genes, respectively, leading to severe muscle weakness and degeneration. The cause of the disease has been well characterized and a number of animal models are available for pre-clinical studies to test potential therapeutic interventions. To facilitate transition from drug discovery to clinical trials, standardized procedures and natural disease history data were collected for these mouse models. Implementing the TREAD-NMD standardized operating procedures, we here subjected LGMD2D (SGCA-null), LGMD2F (SGCD-null) and wild type (C57BL/6J) mice to five functional tests from the age of 4 to 32 weeks. To assess whether the functional test regime interfered with disease pathology, sedentary groups were taken along. Muscle physiology testing of tibialis anterior muscle was performed at the age of 34 weeks. Muscle histopathology and gene expression was analysed in skeletal muscles and heart. Muscle histopathology and gene expression was analysed in skeletal muscles and heart. Mice successfully accomplished the functional tests, which did not interfere with disease pathology. Muscle function of SGCA- and SGCD-null mice was impaired and declined over time. Interestingly, female SGCD-null mice outperformed males in the two and four limb hanging tests, which proved the most suitable non-invasive tests to assess muscle function. Muscle physiology testing of tibialis anterior muscle revealed lower specific force and higher susceptibility to eccentric-induced damage in LGMD mice. Analyzing muscle histopathology and gene expression, we identified the diaphragm as the most affected muscle in LGMD strains. Cardiac fibrosis was found in SGCD-null mice, being more severe in males than in females. Our study offers a comprehensive natural history dataset which will be useful to design standardized tests and future pre
Marras, Simone; Kopera, Michal A.; Constantinescu, Emil M.; Suckale, Jenny; Giraldo, Francis X.
2018-04-01
The high-order numerical solution of the non-linear shallow water equations is susceptible to Gibbs oscillations in the proximity of strong gradients. In this paper, we tackle this issue by presenting a shock capturing model based on the numerical residual of the solution. Via numerical tests, we demonstrate that the model removes the spurious oscillations in the proximity of strong wave fronts while preserving their strength. Furthermore, for coarse grids, it prevents energy from building up at small wave-numbers. When applied to the continuity equation to stabilize the water surface, the addition of the shock capturing scheme does not affect mass conservation. We found that our model improves the continuous and discontinuous Galerkin solutions alike in the proximity of sharp fronts propagating on wet surfaces. In the presence of wet/dry interfaces, however, the model needs to be enhanced with the addition of an inundation scheme which, however, we do not address in this paper.
Autovino, Dario; Negm, Amro; Rallo, Giovanni; Provenzano, Giuseppe
2016-04-01
In Mediterranean countries characterized by limited water resources for agricultural and societal sectors, irrigation management plays a major role to improve water use efficiency at farm scale, mainly where irrigation systems are correctly designed to guarantee a suitable application efficiency and the uniform water distribution throughout the field. In the last two decades, physically-based agro-hydrological models have been developed to simulate mass and energy exchange processes in the soil-plant-atmosphere (SPA) system. Mechanistic models like HYDRUS 2D/3D (Šimunek et al., 2011) have been proposed to simulate all the components of water balance, including actual crop transpiration fluxes estimated according to a soil potential-dependent sink term. Even though the suitability of these models to simulate the temporal dynamics of soil and crop water status has been reported in the literature for different horticultural crops, a few researches have been considering arboreal crops where the higher gradients of root water uptake are the combination between the localized irrigation supply and the three dimensional root system distribution. The main objective of the paper was to assess the performance of HYDRUS-2D model to evaluate soil water contents and transpiration fluxes of an olive orchard irrigated with two different water distribution systems. Experiments were carried out in Castelvetrano (Sicily) during irrigation seasons 2011 and 2012, in a commercial farm specialized in the production of table olives (Olea europaea L., var. Nocellara del Belice), representing the typical variety of the surrounding area. During the first season, irrigation water was provided by a single lateral placed along the plant row with four emitters per plant (ordinary irrigation), whereas during the second season a grid of emitters laid on the soil was installed in order to irrigate the whole soil surface around the selected trees. The model performance was assessed based on the
2-D Model Test Study of the Breakwater at Porto de Dande , Angola
DEFF Research Database (Denmark)
Andersen, Thomas Lykke; Ramirez, Jorge Robert Rodriguez; Burcharth, Hans F.
This report deals with a two-dimensional model test study of the new breakwater at Porto de Dande, Angola. One cross-section was tested for stability and overtopping in various sea conditions. The length scale used for the model tests was 1:32. Unless otherwise specified all values given in this ......This report deals with a two-dimensional model test study of the new breakwater at Porto de Dande, Angola. One cross-section was tested for stability and overtopping in various sea conditions. The length scale used for the model tests was 1:32. Unless otherwise specified all values given...
Electro-mechanical dynamics of spiral waves in a discrete 2D model of human atrial tissue.
Directory of Open Access Journals (Sweden)
Paul Brocklehurst
Full Text Available We investigate the effect of mechano-electrical feedback and atrial fibrillation induced electrical remodelling (AFER of cellular ion channel properties on the dynamics of spiral waves in a discrete 2D model of human atrial tissue. The tissue electro-mechanics are modelled using the discrete element method (DEM. Millions of bonded DEM particles form a network of coupled atrial cells representing 2D cardiac tissue, allowing simulations of the dynamic behaviour of electrical excitation waves and mechanical contraction in the tissue. In the tissue model, each cell is modelled by nine particles, accounting for the features of individual cellular geometry; and discrete inter-cellular spatial arrangement of cells is also considered. The electro-mechanical model of a human atrial single-cell was constructed by strongly coupling the electrophysiological model of Colman et al. to the mechanical myofilament model of Rice et al., with parameters modified based on experimental data. A stretch-activated channel was incorporated into the model to simulate the mechano-electrical feedback. In order to investigate the effect of mechano-electrical feedback on the dynamics of spiral waves, simulations of spiral waves were conducted in both the electromechanical model and the electrical-only model in normal and AFER conditions, to allow direct comparison of the results between the models. Dynamics of spiral waves were characterized by tracing their tip trajectories, stability, excitation frequencies and meandering range of tip trajectories. It was shown that the developed DEM method provides a stable and efficient model of human atrial tissue with considerations of the intrinsically discrete and anisotropic properties of the atrial tissue, which are challenges to handle in traditional continuum mechanics models. This study provides mechanistic insights into the complex behaviours of spiral waves and the genesis of atrial fibrillation by showing an important role of
Numerical method for a 2D drift diffusion model arising in strained n ...
Indian Academy of Sciences (India)
carrier mobility dependence on the lateral and vertical electric field model is especially considered in the formulation. By using the .... effects of electric field on mobility, we use a simplified mobility model [19], see eq. (16). The effects of the .... Our simulator predicted that the drive current of strained MOSFET is higher than.
The critical points of the multimatrix model as the theories of 2-d W-gravity
International Nuclear Information System (INIS)
Awada, M.A.; Qiu, Zongan.
1990-03-01
We further explore the connections between the generalized KdV hierarchy, the multimatrix model and W n -gravity. We show that the Lax-pair formulation of the generalized KdV hierarchy is nothing but the Hamiltonian equations of W-gravity. Thus we demonstrate that the multicritical points of the multimatrix model are W-gravity theories. 16 refs
Directory of Open Access Journals (Sweden)
Kowit Boonrawd
2015-04-01
Full Text Available A coupling of a 1-D flood routing model and quasi 2-D floodplain inundation model is applied for mapping spacetime flood extent. The routing model is formulated based on a non-linear storage-discharge relationship which is converted from an observed and synthetic rating curve. To draw the rating curve, required parameters for each reaches are estimated from hydraulic properties, floodplain geometry and vegetation and building cover of compound channels. The shape of the floodplain is defined by using fitting exercise based on the reverse approach between past and simulated inundation flood extent, to solve the current problem of inadequate topographic input data for floodplain. Mapping of daily flood can be generated relying on flat water levels. The quasi 2-D raster model is tested and applied to generate more realistic water surface and is used to estimate flood extent. The model is applied to the floodplains of Chiang Mai, north of Thailand and used to estimate a time series of hourly flood maps. Extending from daily to hourly flood extent, mapping development provides more details of flood inundation extent and depth.
Kolkoori, S R; Rahman, M-U; Chinta, P K; Ktreutzbruck, M; Rethmeier, M; Prager, J
2013-02-01
Ultrasound propagation in inhomogeneous anisotropic materials is difficult to examine because of the directional dependency of elastic properties. Simulation tools play an important role in developing advanced reliable ultrasonic non destructive testing techniques for the inspection of anisotropic materials particularly austenitic cladded materials, austenitic welds and dissimilar welds. In this contribution we present an adapted 2D ray tracing model for evaluating ultrasonic wave fields quantitatively in inhomogeneous anisotropic materials. Inhomogeneity in the anisotropic material is represented by discretizing into several homogeneous layers. According to ray tracing model, ultrasonic ray paths are traced during its energy propagation through various discretized layers of the material and at each interface the problem of reflection and transmission is solved. The presented algorithm evaluates the transducer excited ultrasonic fields accurately by taking into account the directivity of the transducer, divergence of the ray bundle, density of rays and phase relations as well as transmission coefficients. The ray tracing model is able to calculate the ultrasonic wave fields generated by a point source as well as a finite dimension transducer. The ray tracing model results are validated quantitatively with the results obtained from 2D Elastodynamic Finite Integration Technique (EFIT) on several configurations generally occurring in the ultrasonic non destructive testing of anisotropic materials. Finally, the quantitative comparison of ray tracing model results with experiments on 32mm thick austenitic weld material and 62mm thick austenitic cladded material is discussed. Copyright © 2012 Elsevier B.V. All rights reserved.
Application of 2-D sediment model to fluctuating backwater area of Yangtze River
Directory of Open Access Journals (Sweden)
Yong Fan
2009-09-01
Full Text Available Based on the characteristics of backflow, a two-dimensional mathematical model of sediment movement was established. The complexity of the watercourse boundary at the confluence of the main stream and the tributary was dealt with using a boundary-fitting orthogonal coordinate system. The basic equation of the two-dimensional total sediment load model, the numerical calculation format, and key problems associated with using the orthogonal curvilinear coordinate system were discussed. Water and sediment flow in the Chongqing reach of the Yangtze River were simulated. The calculated water level, flow velocity distribution, amount of silting and scouring, and alluvial distribution are found to be in agreement with the measured data, which indicates that the numerical model and calculation method are reasonable. The model can be used for calculation of flow in a relatively complicated river network.
Hemodynamic simulation of the heart using a 2D model and MR data
DEFF Research Database (Denmark)
Adeler, Pernille Thorup
2002-01-01
. The improvements require changing the geometry, the timing, the mechanical activation of the heart musculature, and the afterload. Furthermore, we introduce a tethering of the otherwise freely floating heart. We evaluate the model from a computational and modelling point of view and find a set of reasonable...... parameter values. This is our reference model, which gives representative simulation results. We compare a simulation using our reference model with an MR velocity data set obtained from a healthy human. The comparison is carried out for the intraventricular velocity field and the velocity time curves over...... the mitral ring and across the aortic outflow tract. The comparison between elocity fields shows a reasonably fair agreement in the general flow pattern: a wide inflow jet, the formation of an anterior vortex during filling, and an outflow jet through the outflow tract. There are some disagreements...
Gragg, E.; Van Wijk, J. W.; Balch, R. S.
2016-12-01
A 40 mile long 2D petroleum system model has been constructed and simulated along a 2D reflection seismic line in the western Anadarko Basin. Petroleum system models are useful for predicting carbon storage capacity, characterizing regional CO2 plume migration risks, predicting how future fields may respond to CO2-EOR via hydrocarbon compositional estimations and characterizing the petroleum system that make sites attractive for storage. This work is part of the Southwest Regional Partnership on Carbon Sequestration Phase III large scale injection operation at Farnsworth Unit Ochiltree Co., Texas. Farnsworth Unit is a mature oil field producing from Morrowan Sandstone incised valley deposits. The project goal is to evaluate the injection and storage of 1 million metric tons of man-made CO2. Geologic carbon storage and utilization via CO2-enhanced oil recovery operations is a method under active research which aims to mitigate climate change via emission reductions while meeting current energy demands. The 2D model was constructed using 2D regional reflection seismic data, geophysical logs and core data. Simulations are forward modeled over 542 Ma of the Anadarko Basins geologic history. The research illustrates (1) in the unlikely case of CO2 leakage out of the reservoir, buoyancy driven regional migration risk is to the northwest-northeast (2) Morrowan play hydrocarbons in the Northeast Texas Panhandle dominantly migrated from the Thirteen Finger Limestone further basinward (3) the regions tectonic evolution has played an important role on the pressure and hydraulic history of reservoirs. Farnsworth's reservoir was discovered as under-pressured, the exact process(s) giving rise to this condition are not well-understood and need further investigation. Moreover, the heat flow model used in this study will aid understanding of the diagenetic evolution of the reservoir and caprocks better. The petroleum system modeling conducted here has accurately predicted 1st order
Enhanced Kalman Filtering for a 2D CFD NS Wind Farm Flow Model
International Nuclear Information System (INIS)
Doekemeijer, B M; Van Wingerden, J W; Boersma, S; Pao, L Y
2016-01-01
Wind turbines are often grouped together for financial reasons, but due to wake development this usually results in decreased turbine lifetimes and power capture, and thereby an increased levelized cost of energy (LCOE). Wind farm control aims to minimize this cost by operating turbines at their optimal control settings. Most state-of-the-art control algorithms are open-loop and rely on low fidelity, static flow models. Closed-loop control relying on a dynamic model and state observer has real potential to further decrease wind's LCOE, but is often too computationally expensive for practical use. In this paper two time-efficient Kalman filter (KF) variants are outlined incorporating the medium fidelity, dynamic flow model “WindFarmSimulator” (WFSim). This model relies on a discretized set of Navier-Stokes equations in two dimensions to predict the flow in wind farms at low computational cost. The filters implemented are an Ensemble KF and an Approximate KF. Simulations in which a high fidelity simulation model represents the true wind farm show that these filters are 10"1 —10"2 times faster than a regular KF with comparable or better performance, correcting for wake dynamics that are not modeled in WFSim (noticeably, wake meandering and turbine hub effects). This is a first big step towards real-time closed-loop control for wind farms. (paper)
Baryon acoustic oscillations in 2D: Modeling redshift-space power spectrum from perturbation theory
Taruya, Atsushi; Nishimichi, Takahiro; Saito, Shun
2010-09-01
We present an improved prescription for the matter power spectrum in redshift space taking proper account of both nonlinear gravitational clustering and redshift distortion, which are of particular importance for accurately modeling baryon acoustic oscillations (BAOs). Contrary to the models of redshift distortion phenomenologically introduced but frequently used in the literature, the new model includes the corrections arising from the nonlinear coupling between the density and velocity fields associated with two competitive effects of redshift distortion, i.e., Kaiser and Finger-of-God effects. Based on the improved treatment of perturbation theory for gravitational clustering, we compare our model predictions with the monopole and quadrupole power spectra of N-body simulations, and an excellent agreement is achieved over the scales of BAOs. Potential impacts on constraining dark energy and modified gravity from the redshift-space power spectrum are also investigated based on the Fisher-matrix formalism, particularly focusing on the measurements of the Hubble parameter, angular diameter distance, and growth rate for structure formation. We find that the existing phenomenological models of redshift distortion produce a systematic error on measurements of the angular diameter distance and Hubble parameter by 1%-2% , and the growth-rate parameter by ˜5%, which would become non-negligible for future galaxy surveys. Correctly modeling redshift distortion is thus essential, and the new prescription for the redshift-space power spectrum including the nonlinear corrections can be used as an accurate theoretical template for anisotropic BAOs.
From 2D to 3D: Using Illumination Cones to Build 3d Face Model
International Nuclear Information System (INIS)
Xiao, S S; Jin, M
2006-01-01
To solve the problem derivate by lighting condition and position of the camera, a new method using illumination cones to build 3d face model has been proposed. Due to illumination variability, the same object can show dramatic difference even as being viewed in fixed pose. To handle this variability, an object recognition system must employ a representation that is either invariant to, or can model this variability. The proposed technique presents an appearance-based method for modeling the variability due to illumination in the images of objects. The method differs from past appearance-based methods. Evenmore, a small set of training images is used to generate a representation that the illumination cone models the complete set of images of an object with Lambertian reflectance surface under a combination of arbitrary point light sources at infinity. After building up the illumination cones, researches focus on how to present the 3d model of the face. Combining illumination and texture feature to build up 3d model of the face make it easy solving the problem in recognition of face under different pose
2-D hydro-viscoelastic model for convective drying of deformable and unsaturated porous material
Hassini, Lamine; Raja, Lamloumi; Lecompte-Nana, Gisèle Laure; Elcafsi, Mohamed Afif
2017-04-01
The aim of this work was to simulate in two dimensions the spatio-temporal evolution of the moisture content, the temperature, the solid (dry matter) concentration, the dry product total porosity, the gas porosity, and the mechanical stress within a deformable and unsaturated product during convective drying. The material under study was an elongated cellulose-clay composite sample with a square section placed in hot air flow. Currently, this innovative composite is used in the processing of boxes devoted to the preservation of heritage and precious objects against fire damage and other degradation (moisture, insects, etc.). A comprehensive and rigorous hydrothermal model had been merged with a dynamic linear viscoelasticity model based on Bishop's effective stress theory, assuming that the stress tensor is the sum of solid, liquid, and gas stresses. The material viscoelastic properties were measured by means of stress relaxation tests for different water contents. The viscoelastic behaviour was described by a generalized Maxwell model whose parameters were correlated to the water content. The equations of our model were solved by means of the 'COMSOL Multiphysics' software. The hydrothermal part of the model was validated by comparison with experimental drying curves obtained in a laboratory hot-air dryer. The simulations of the spatio-temporal distributions of mechanical stress were performed and interpreted in terms of material potential damage. The sample shape was also predicted all over the drying process.
3D continuum phonon model for group-IV 2D materials
Willatzen, Morten
2017-06-30
A general three-dimensional continuum model of phonons in two-dimensional materials is developed. Our first-principles derivation includes full consideration of the lattice anisotropy and flexural modes perpendicular to the layers and can thus be applied to any two-dimensional material. In this paper, we use the model to not only compare the phonon spectra among the group-IV materials but also to study whether these phonons differ from those of a compound material such as molybdenum disulfide. The origin of quadratic modes is clarified. Mode coupling for both graphene and silicene is obtained, contrary to previous works. Our model allows us to predict the existence of confined optical phonon modes for the group-IV materials but not for molybdenum disulfide. A comparison of the long-wavelength modes to density-functional results is included.
3D continuum phonon model for group-IV 2D materials.
Willatzen, Morten; Lew Yan Voon, Lok C; Gandi, Appala Naidu; Schwingenschlögl, Udo
2017-01-01
A general three-dimensional continuum model of phonons in two-dimensional materials is developed. Our first-principles derivation includes full consideration of the lattice anisotropy and flexural modes perpendicular to the layers and can thus be applied to any two-dimensional material. In this paper, we use the model to not only compare the phonon spectra among the group-IV materials but also to study whether these phonons differ from those of a compound material such as molybdenum disulfide. The origin of quadratic modes is clarified. Mode coupling for both graphene and silicene is obtained, contrary to previous works. Our model allows us to predict the existence of confined optical phonon modes for the group-IV materials but not for molybdenum disulfide. A comparison of the long-wavelength modes to density-functional results is included.
Multitemporal SAR Data and 2D Hydrodynamic Model Flood Scenario Dynamics Assessment
Directory of Open Access Journals (Sweden)
Santina Scarpino
2018-03-01
Full Text Available The increasing number of floods and the severity of their consequences, which is caused by phenomena, such as climate change and uncontrolled urbanization, create a growing need to develop operational procedures and tools for accurate and timely flood mapping and management. Synthetic Aperture Radar (SAR, with its day, night, and cloud-penetrating capacity, has proven to be a very useful source of information during calibration of hydrodynamic models considered indispensable tools for near real-time flood forecasting and monitoring. The paper begins with the analysis of radar signatures of temporal series of SAR data, by exploiting the short revisit time of the images that are provided by the Cosmo-SkyMed constellation of four satellites, in combination with a Digital Elevation Model for the extraction of flood extent and spatially distributed water depth in a flat area with complex topography during a flood event. These SAR-based hazard maps were then used to perform a bi-dimensional hydraulic model calibration on the November 2010 flood event at the mouth of the Bradano River in Basilicata, Italy. Once the best fit between flood predictions of hydrodynamic models was identified and the efficacy of SAR data in correcting hydrodynamic inconsistencies with regard to reliable assessment of flood extent and water-depth maps was shown by validation with the December 2013 Bradano River event. Based on calibration and validation results, the paper aims to show how the combination of the time series of Synthetic Aperture Radar (SAR and Digital Elevation Model (DEM derived water-depth maps with the data from the hydrodynamic model can provide valuable information for flood dynamics monitoring in a flat area with complex topography. Future research should focus on the integration and implementation of the semi-automatic proposed method in an operational system for near real-time flood management.
A simple 2-D model for the evolution of an island-arc system
Zharinov, S. E.; Demin, S. S.
1990-07-01
Slow seismotectonic movements along inclined deep fault planes under compressive horizontal stresses are supposed to be the principal mechanism controlling the structure and processes in island-arc systems. In order to treat the stress variations caused by this mechanism, a simple geomechanical model is investigated. We consider a shearing surface crack embedded in a homogeneous elastic half-space. The key element of the model is viscous interaction between the sides of the crack, the viscosity varying with depth. The model differs from the classical steady-state mode of subduction by nonstationary creep processes on deep faults and possibly by cyclical evolution of island-arc systems. The results of our numerical analysis are in good agreement with geological, geophysical and seismological data. (i) Vertical displacements of the free surface in the model fit well with the typical topography of a trench—arc-basement rise—back-arc basin system. (ii) The Benioff seismic zone is supposed to be formed due to the concentration of shear stresses near the fault plane. The characteristic patterns of seismicity, the fine geometry of Benioff zones, and their double-planed structure can be explained in terms of our model. (iii) A zone of considerable heat generation caused by viscous dissipation along the fault plane is found within a narrow area in the depth range 100-200 km. Moreover, the island-arc basement rise is characterized in the model by a relative tension of a few tens or even hundreds of bars, while at depths of 100-150 km below the surface, additional compression of the same order of magnitude acts. The magmatic plumbing system may be visualised as a "toothpaste tube" or a sponge filled with magma which is squeezed from the depths to the surface due to the redistribution of the tectonic stresses only. This can explain the physical origin of island-arc magmatism and the typical position of volcanic belts.
An explicit formula for the interface tension of the 2D Potts model
Borgs, Christian; Janke, Wolfhard
1992-11-01
We consider the exact correlation length calculations for the two-dimensional Potts model at the transition point β_t by Klümper, Schadschneider and Zittartz, and by Buffenoir and Wallon. We argue that the correlation length calculated by the latter authors is the correlation length in the disordered phase and then combine their result with duality and the assumption of complete wetting to give an explicit formula for the order-disorder interface tension σ_od of this model. The result is used to clarify a controversy stemming from different numerical simulations of σ_od.
3D continuum phonon model for group-IV 2D materials
DEFF Research Database (Denmark)
Willatzen, Morten; Lew Yan Voon, Lok C.; Gandi, Appala Naidu
2017-01-01
. In this paper, we use the model to not only compare the phonon spectra among the group-IV materials but also to study whether these phonons differ from those of a compound material such as molybdenum disulfide. The origin of quadratic modes is clarified. Mode coupling for both graphene and silicene is obtained......, contrary to previous works. Our model allows us to predict the existence of confined optical phonon modes for the group-IV materials but not for molybdenum disulfide. A comparison of the long-wavelength modes to density-functional results is included....
Bistable flow occurrence in the 2D model of a steam turbine valve
Pavel, Procházka; Václav, Uruba
2017-09-01
The internal flow inside a steam turbine valve was investigated experimentally using PIV measurement. The valve model was proposed to be two-dimensional. The model was connected to the blow-down wind tunnel. The flow conditions were set by the different position of the valve plug. Several angles of the diffuser by diverse radii were investigated concerning flow separation and flow dynamics. It was found that the flow takes one of two possible bistable modes. The first regime is characterized by a massive flow separation just at the beginning of the diffuser section on the one side. The second regime is axisymmetric and the flow separation is not detected at all.
Semi-2D modeling of river morphological changes caused by exceptional flooding
Directory of Open Access Journals (Sweden)
Mahdi Tew-Fik
2017-01-01
Full Text Available This paper presents the application of the model, MHYSER 1.0 (Model for the HYdraulics of SEdiments in Rivers, version 1.0, to study river morphological changes due to exceptional flooding. MHYSER 1.0 is a semi-two-dimensional model using the stream tubes concept to achieve lateral variations of velocity, flow stresses and sediment transport rate. Each stream tube has the same conveyance as the other ones. In MHYSER 1.0, the uncoupled approach is used to solve the set of conservation equations’. After the backwater calculation, the river is divided in a finite number of stream tubes of equal conveyances. The sediment routing and bed adjustments calculations are accomplished separately along each stream tube taking into account lateral mass exchanges. MHYSER 1.0 is applied to the Ha! Ha! River (Quebec, Canada, a tributary of the Saguenay River, for the 1996 “downpour“. The results show good correlation of with collected data. This application shows the capabilities of this model and predicts its promising role in solving complex real engineering cases.
Numerical method for a 2D drift diffusion model arising in strained n ...
Indian Academy of Sciences (India)
This paper reports the calculation of electron transport in metal oxide semiconductor field effects transistors (MOSFETs) with biaxially tensile strained silicon channel. The calculation is formulated based on two-dimensional drift diffusion model (DDM) including strain effects. The carrier mobility dependence on the lateral and ...
2D Modelling of Mechanical Stress Evolution and Electromigration in Confined Aluminium Interconnects
Petrescu, V.; Mouthaan, A.J.
1997-01-01
A complete description for mechanical stress evolution and electromigration in confined Al interconnects, taking into account the microstructure features, is presented in this paper. In the last years there were proposed several 1D models for the time-dependent evolution of the mechanical stress in
Adaptive Fault-Tolerant Routing in 2D Mesh with Cracky Rectangular Model
Directory of Open Access Journals (Sweden)
Yi Yang
2014-01-01
Full Text Available This paper mainly focuses on routing in two-dimensional mesh networks. We propose a novel faulty block model, which is cracky rectangular block, for fault-tolerant adaptive routing. All the faulty nodes and faulty links are surrounded in this type of block, which is a convex structure, in order to avoid routing livelock. Additionally, the model constructs the interior spanning forest for each block in order to keep in touch with the nodes inside of each block. The procedure for block construction is dynamically and totally distributed. The construction algorithm is simple and ease of implementation. And this is a fully adaptive block which will dynamically adjust its scale in accordance with the situation of networks, either the fault emergence or the fault recovery, without shutdown of the system. Based on this model, we also develop a distributed fault-tolerant routing algorithm. Then we give the formal proof for this algorithm to guarantee that messages will always reach their destinations if and only if the destination nodes keep connecting with these mesh networks. So the new model and routing algorithm maximize the availability of the nodes in networks. This is a noticeable overall improvement of fault tolerability of the system.
Point cloud data fusion for enhancing 2d urban flood modelling
Meesuk, V.
2017-01-01
Modelling urban flood dynamics requires proper handling of a number of complex urban features. Although high-resolution topographic data can nowadays be obtained from aerial LiDAR surveys, such top-view LiDAR data still have difficulties to represent some key components of urban features.
The variational 2D Boussinesq model for wave propagation over a shoal
Adytia, D.; van Groesen, Embrecht W.C.
2011-01-01
The Variational Boussinesq Model (VBM) for waves (Klopman et al. 2010) is based on the Hamiltonian structure of gravity surface waves. In its approximation, the fluid potential in the kinetic energy is approximated by the sum of its value at the free surface and a linear combination of vertical
Dynamic Linkages Between the Transition Zone & Surface Plate Motions in 2D Models of Subduction
Arredondo, K.; Billen, M. I.
2013-12-01
While slab pull is considered the dominant force controlling plate motion and speed, its magnitude is controlled by slab behavior in the mantle, where tomographic studies show a wide range of possibilities from direct penetration to folding, or stagnation directly above the lower mantle (e.g. Fukao et al., 2009). Geodynamic studies have investigated various parameters, such as plate age and two phase transitions, to recreate observed behavior (e.g. Běhounková and Cízková, 2008). However, past geodynamic models have left out known slab characteristics that may have a large impact on slab behavior and our understanding of subduction processes. Mineral experiments and seismic observations have indicated the existence of additional phase transitions in the mantle transition zone that may produce buoyancy forces large enough to affect the descent of a subducting slab (e.g. Ricard et al., 2005). The current study systematically tests different common assumptions used in geodynamic models: kinematic versus free-slip boundary conditions, the effects of adiabatic heating, viscous dissipation and latent heat, compositional layering and a more complete suite of phase transitions. Final models have a complete energy equation, with eclogite, harzburgite and pyrolite lithosphere compositional layers, and seven composition-dependent phase transitions within the olivine, pyroxene and garnet polymorph minerals. Results show important feedback loops between different assumptions and new behavior from the most complete models. Kinematic models show slab weakening or breaking above the 660 km boundary and between compositional layers. The behavior in dynamic models with a free-moving trench and overriding plate is compared to the more commonly found kinematic models. The new behavior may have important implications for the depth distribution of deep earthquakes within the slab. Though the thermodynamic parameters of certain phase transitions may be uncertain, their presence and
A simple 2D SOC model for one of the main sources of geomagnetic disturbances: Flares
International Nuclear Information System (INIS)
Meirelles, M.C.; Dias, V.H.A.; Oliva, D.; Papa, A.R.R.
2010-01-01
We introduce a simple model for solar flares, one of the main sources of geomagnetic disturbances. We have obtained power-laws for the probability distribution functions of some relevant physical characteristics of flares which could serve as the fingerprint of a critical state at the base of such phenomena and, given that we have not introduced a fine tune mechanism, of self-organized criticality. We compare our results with some recent experimental work on the statistics of flares and analyze the possible connection of these power laws with others already found by our group in geomagnetic disturbances distributions. We also present some limitations of our model as well as possible extensions and corrections to be taken into account in future works.
A 2D Time Domain DRBEM Computer Model for MagnetoThermoelastic Coupled Wave Propagation Problems
Directory of Open Access Journals (Sweden)
Mohamed Abdelsabour Fahmy
2014-07-01
Full Text Available A numerical computer model based on the dual reciprocity boundary element method (DRBEM is extended to study magneto-thermoelastic coupled wave propagation problems with relaxation times involving anisotropic functionally graded solids. The model formulation is tested through its application to the problem of a solid placed in a constant primary magnetic field acting in the direction of the z-axis and rotating about this axis with a constant angular velocity. In the case of two-dimensional deformation, an implicit-explicit time domain DRBEM was presented and implemented to obtain the solution for the displacement and temperature fields. A comparison of the results is presented graphically in the context of Lord and Shulman (LS and Green and Lindsay (GL theories. Numerical results that demonstrate the validity of the proposed method are also presented graphically.
Comparison Between 2D Turbulence Model ESEL and Experimental Data from AUG and Compass Tokamaks
Czech Academy of Sciences Publication Activity Database
Ondáč, Peter; Horáček, Jan; Seidl, Jakub; Vondráček, Petr; Müller, H.W.; Adámek, Jiří; Nielsen, A.H.
2015-01-01
Roč. 55, č. 2 (2015), s. 128-135 ISSN 1210-2709 R&D Projects: GA ČR(CZ) GAP205/12/2327; GA MŠk(CZ) LM2011021 Institutional support: RVO:61389021 Keywords : turbulence * tokamak * computer model * probe measurements Subject RIV: BL - Plasma and Gas Discharge Physics https://ojs.cvut.cz/ojs/index.php/ap/article/viewFile/2257/2816
2016-06-01
MODELING OF IMPACT RESPONSE OF HETEROGENEOUS ENERGETIC COMPOSITES submitted to Dr. Douglas Allen Dalton Defense Threat Reduction Agency J9-BAS...materials from density functional theory with van der Waals, thermal, and zero-point energy corrections," Applied Physics Letters, vol. 97, Dec 20 2010...REDUCTION AGENCY 8725 JOHN J. KINGMAN ROAD STOP 6201 FORT BELVOIR, VA 22060 ATTN: A. DALTON DEFENSE TECHNICAL INFORMATION CENTER
Phase diagram of 2D Hubbard model by simulated annealing mean field approximation
International Nuclear Information System (INIS)
Kato, Masaru; Kitagaki, Takashi
1991-01-01
In order to investigate the stable magnetic structure of the Hubbard model on a square lattice, we utilize the dynamical simulated annealing method which proposed by R. Car and M. Parrinello. Results of simulations on a 10 x 10 lattice system with 80 electrons under assumption of collinear magnetic structure that the most stable state is incommensurate spin density wave state with periodic domain wall. (orig.)
A hierarchical lattice spring model to simulate the mechanics of 2-D materials-based composites
Directory of Open Access Journals (Sweden)
Lucas eBrely
2015-07-01
Full Text Available In the field of engineering materials, strength and toughness are typically two mutually exclusive properties. Structural biological materials such as bone, tendon or dentin have resolved this conflict and show unprecedented damage tolerance, toughness and strength levels. The common feature of these materials is their hierarchical heterogeneous structure, which contributes to increased energy dissipation before failure occurring at different scale levels. These structural properties are the key to exceptional bioinspired material mechanical properties, in particular for nanocomposites. Here, we develop a numerical model in order to simulate the mechanisms involved in damage progression and energy dissipation at different size scales in nano- and macro-composites, which depend both on the heterogeneity of the material and on the type of hierarchical structure. Both these aspects have been incorporated into a 2-dimensional model based on a Lattice Spring Model, accounting for geometrical nonlinearities and including statistically-based fracture phenomena. The model has been validated by comparing numerical results to continuum and fracture mechanics results as well as finite elements simulations, and then employed to study how structural aspects impact on hierarchical composite material properties. Results obtained with the numerical code highlight the dependence of stress distributions on matrix properties and reinforcement dispersion, geometry and properties, and how failure of sacrificial elements is directly involved in the damage tolerance of the material. Thanks to the rapidly developing field of nanocomposite manufacture, it is already possible to artificially create materials with multi-scale hierarchical reinforcements. The developed code could be a valuable support in the design and optimization of these advanced materials, drawing inspiration and going beyond biological materials with exceptional mechanical properties.
Ma, Z.; Masters, G.
2014-12-01
We have developed a technique that uses a cluster analysis method to measure Rayleigh wave phase and amplitude anomalies. The measurements are made on the vertical components of all permanent stations recording LHZ data from IRIS. We currently consider earthquakes with Ms>5.5 between 1990 and 2007. Joint inversions for 2D phase velocity and attenuation maps are performed, allowing the coupling through physical dispersion (e.g. Zhou 2009). As demonstrated in Dalton and Ekstrom (2006), correcting the effect of focusing-defocusing is crucial in order to obtain reliable attenuation structures. Ray theory, which has been used to date, may not give reliable predictions of such effects, because it depends strongly on short wavelength velocity structures and so is very sensitive to how the phase velocity maps are smoothed. Instead, we use the 2D finite frequency amplitude kernel (Zhou et al, 2004) to model the focusing-defocusing effect. Attenuation models and evaluations of model error and resolution will be presented.
Astorino, Maria Denise; Frezza, Fabrizio; Tedeschi, Nicola
2018-03-01
The analysis of the transmission and reflection spectra of stacked slot-based 2D periodic structures of arbitrary geometry and the ability to devise and control their electromagnetic responses have been a matter of extensive research for many decades. The purpose of this paper is to develop an equivalent Π circuit model based on the transmission-line theory and Floquet harmonic interactions, for broadband and short longitudinal period analysis. The proposed circuit model overcomes the limits of identical and symmetrical configurations imposed by the even/odd excitation approach, exploiting both the circuit topology of a single 2D periodic array of apertures and the ABCD matrix formalism. The transmission spectra obtained through the equivalent-circuit model have been validated by comparison with full-wave simulations carried out with a finite-element commercial electromagnetic solver. This allowed for a physical insight into the spectral and angular responses of multilayer devices with arbitrary aperture shapes, guaranteeing a noticeable saving of computational resources.
Neal, J. C.; Wood, M.; Bermúdez, M.; Hostache, R.; Freer, J. E.; Bates, P. D.; Coxon, G.
2017-12-01
Remote sensing of flood inundation extent has long been a potential source of data for constraining and correcting simulations of floodplain inundation. Hydrodynamic models and the computing resources to run them have developed to the extent that simulation of flood inundation in two-dimensional space is now feasible over large river basins in near real-time. However, despite substantial evidence that there is useful information content within inundation extent data, even from low resolution SAR such as that gathered by Envisat ASAR in wide swath mode, making use of the information in a data assimilation system has proved difficult. He we review recent applications of the Ensemble Kalman Filter (EnKF) and Particle Filter for assimilating SAR data, with a focus on the River Severn UK and compare these with complementary research that has looked at the internal error sources and boundary condition errors using detailed terrestrial data that is not available in most locations. Previous applications of the EnKF to this reach have focused on upstream boundary conditions as the source of flow error, however this description of errors was too simplistic for the simulation of summer flood events where localised intense rainfall can be substantial. Therefore, we evaluate the introduction of uncertain lateral inflows to the ensemble. A further limitation of the existing EnKF based methods is the need to convert flood extent to water surface elevations by intersecting the shoreline location with a high quality digital elevation model (e.g. LiDAR). To simplify this data processing step, we evaluate a method to directly assimilate inundation extent as a EnKF model state rather than assimilating water heights, potentially allowing the scheme to be used where high-quality terrain data are sparse.
Modelling and Experimental Verification of a DEAP based 2-D rotational positioner
DEFF Research Database (Denmark)
Iskandarani, Yosef; Bilberg, Arne; Sarban, Rahimullah
limited to 3000 V. This work will examine the ability of positioning a shaft coupled to a laser beam pointer in x-y direction which will provide insight into (a) the practicality of using the material for two dimensional rotational positioning and (b) to highlight feasible positioning applications. A test...... of the active actuators with 0.5 kV steps. For each, of the testing combinations the angle target was determined and results compared with the model of the two dimensional positioner. The feedback of positioner was not addressed in this work; through the relevant control theory which will be implemented...
Flood hazard mapping of Palembang City by using 2D model
Farid, Mohammad; Marlina, Ayu; Kusuma, Muhammad Syahril Badri
2017-11-01
Palembang as the capital city of South Sumatera Province is one of the metropolitan cities in Indonesia that flooded almost every year. Flood in the city is highly related to Musi River Basin. Based on Indonesia National Agency of Disaster Management (BNPB), the level of flood hazard is high. Many natural factors caused flood in the city such as high intensity of rainfall, inadequate drainage capacity, and also backwater flow due to spring tide. Furthermore, anthropogenic factors such as population increase, land cover/use change, and garbage problem make flood problem become worse. The objective of this study is to develop flood hazard map of Palembang City by using two dimensional model. HEC-RAS 5.0 is used as modelling tool which is verified with field observation data. There are 21 sub catchments of Musi River Basin in the flood simulation. The level of flood hazard refers to Head Regulation of BNPB number 2 in 2012 regarding general guideline of disaster risk assessment. The result for 25 year return per iod of flood shows that with 112.47 km2 area of inundation, 14 sub catchments are categorized in high hazard level. It is expected that the hazard map can be used for risk assessment.
Competition Among Reputations in the 2D Sznajd Model: Spontaneous Emergence of Democratic States
Crokidakis, Nuno; Forgerini, Fabricio L.
2012-04-01
We propose a modification in the Sznajd sociophysics model defined on the square lattice. For this purpose, we consider reputation—a mechanism limiting the agents' persuasive power. The reputation is introduced as a time-dependent score, which can be positive or negative. This mechanism avoids dictatorship (full consensus, all spins parallel) for a wide range of model parameters. We consider two different situations: case 1, in which the agents' reputation increases for each persuaded neighbor, and case 2, in which the agents' reputation increases for each persuasion and decreases when a neighbor keeps his opinion. Our results show that the introduction of reputation avoids full consensus even for initial densities of up spins greater than 1/2. The relaxation times follow a log-normal-like distribution in both cases, but they are larger in case 2 due to the competition among reputations. In addition, we show that the usual phase transition occurs and depends on the initial concentration d of individuals with the same opinion, but the critical points d c in the two cases are different.
2-D edge modelling: convergence and results for next step devices in the high recycling regime
International Nuclear Information System (INIS)
Pacher, H.D.; D'haeseleer, W.D.; Pacher, G.W.
1992-01-01
In the present work, we apply the Braams B-2 code to a next step device, with particular emphasis on convergence of the solutions and on the scaling of the peak power load per unit area on the divertor plate, f p , on the electron temperature T e,p at the point of peak power load. A double null geometry is chosen (ITER as defined, 22 MA, 6 m). The input power P to one outer divertor is 0.4 of the total power to the SOL and 0.05 of the fusion power, and f p is given without safety and peaking factors. Recycling is treated by an analytical model including atoms and molecules. The model is appropriate for the high recycling regime down to T e,p ∼5-10 eV as long as impurity radiation can be neglected, but not beyond since sideways neutral motion is not included. DT ionization and radiation losses are included. Only D-T ions are treated, but collision frequencies are corrected for impurities. Radial transport coefficients are uniform in space, with χ e =2 m 2 /s and D=χ i =χ e /3=const, for most of the cases but Bohm-like scaling is also investigated. (author) 10 refs., 7 figs
Image analysis and 2D/3D modeling of the MOX fuel microstructure
International Nuclear Information System (INIS)
Oudinet, Ghislain
2003-01-01
The microstructure of the MOX fuel, made with UO 2 and PuO 2 , determines his 'in pile' behavior. The french companies CEA and COGEMA are highly interested in its description by image analysis, which is the object of the present work. The segmentation algorithms described here use pictures issued from a microprobe and a SEM, to analyse the plutonium and porosity distribution in the fuel pellets. They are innovating, automated and robust enough to be used with a small data set. They have been successfully tested on different fuels, before and after irradiation. Three-dimensional informations have been computed with a genetic algorithm. The obtained 3D object size distributions allowed the modeling of many different industrial and research fuels. 3D reconstruction is accurate and stable, and provides a basis for different studies among which the study of the MOX fuel 'in pile' behavior. (author)
Parameterised Model of 2D Combustor Exit Flow Conditions for High-Pressure Turbine Simulations
Directory of Open Access Journals (Sweden)
Marius Schneider
2017-12-01
Full Text Available An algorithm is presented generating a complete set of inlet boundary conditions for Reynolds-averaged Navier–Stokes computational fluid dynamics (RANS CFD of high-pressure turbines to investigate their interaction with lean and rich burn combustors. The method shall contribute to understanding the sensitivities of turbine aerothermal performance in a systematic approach. The boundary conditions are based on a set of input parameters controlling velocity, temperature, and turbulence fields. All other quantities are derived from operating conditions and additional modelling assumptions. The algorithm is coupled with a CFD solver by applying the generated profiles as inlet boundary conditions. The successive steps to derive consistent flow profiles are described and results are validated against flow fields extracted from combustor CFD.
Finite-size effects for anisotropic 2D Ising model with various boundary conditions
Izmailian, N. Sh
2012-12-01
We analyze the exact partition function of the anisotropic Ising model on finite M × N rectangular lattices under four different boundary conditions (periodic-periodic (pp), periodic-antiperiodic (pa), antiperiodic-periodic (ap) and antiperiodic-antiperiodic (aa)) obtained by Kaufman (1949 Phys. Rev. 76 1232), Wu and Hu (2002 J. Phys. A: Math. Gen. 35 5189) and Kastening (2002 Phys. Rev. E 66 057103)). We express the partition functions in terms of the partition functions Zα, β(J, k) with (α, β) = (0, 0), (1/2, 0), (0, 1/2) and (1/2, 1/2), J is an interaction coupling and k is an anisotropy parameter. Based on such expressions, we then extend the algorithm of Ivashkevich et al (2002 J. Phys. A: Math. Gen. 35 5543) to derive the exact asymptotic expansion of the logarithm of the partition function for all boundary conditions mentioned above. Our result is f = fbulk + ∑∞p = 0fp(ρ, k)S-p - 1, where f is the free energy of the system, fbulk is the free energy of the bulk, S = MN is the area of the lattice and ρ = M/N is the aspect ratio. All coefficients in this expansion are expressed through analytical functions. We have introduced the effective aspect ratio ρeff = ρ/sinh 2Jc and show that for pp and aa boundary conditions all finite size correction terms are invariant under the transformation ρeff → 1/ρeff. This article is part of ‘Lattice models and integrability’, a special issue of Journal of Physics A: Mathematical and Theoretical in honour of F Y Wu's 80th birthday.
Computational study of a magnetic design to improve the diagnosis of malaria: 2D model
Energy Technology Data Exchange (ETDEWEB)
Vyas, Siddharth, E-mail: svyas76@gmail.com [Department of Electrical and Computer Engineering, Drexel University, Philadelphia, PA 19104 (United States); Department of Engineering Technology, Drexel University, Philadelphia, PA 19104 (United States); Genis, Vladimir [Department of Engineering Technology, Drexel University, Philadelphia, PA 19104 (United States); Friedman, Gary [Department of Electrical and Computer Engineering, Drexel University, Philadelphia, PA 19104 (United States)
2017-02-01
This paper investigates the feasibility of a cost effective high gradient magnetic separation based device for the detection and identification of malaria parasites in a blood sample. The design utilizes magnetic properties of hemozoin present in malaria-infected red blood cells (mRBCs) in order to separate and concentrate them inside a microfluidic channel slide for easier examination under the microscope. The design consists of a rectangular microfluidic channel with multiple magnetic wires positioned on top of and underneath it along the length of the channel at a small angle with respect to the channel axis. Strong magnetic field gradients, produced by the wires, exert sufficient magnetic forces on the mRBCs in order to separate and concentrate them in a specific region small enough to fit within the microscope field of view at magnifications typically required to identify the malaria parasite type. The feasibility of the device is studied using a model where the trajectories of the mRBCs inside the channel are determined using first-order ordinary differential equations (ODEs) solved numerically using a multistep ODE solver available within MATLAB. The mRBCs trajectories reveal that it is possible to separate and concentrate the mRBCs in less than 5 min, even in cases of very low parasitemia (1–10 parasites/µL of blood) using blood sample volumes of around 3 µL employed today. - Highlights: • A simple and cost-effective design is presented to improve the diagnosis of malaria. • The design is studied using a computational model. • It is possible to concentrate malaria-infected cells in a small area. • This can improve slide-examination and the efficiency of microscopists. • This can improve diagnosis of low-parasitemia and asymptomatic malaria.
Turco, Michele; Kodešová, Radka; Brunetti, Giuseppe; Nikodem, Antonín; Fér, Miroslav; Piro, Patrizia
2017-11-01
An adequate hydrological description of water flow in permeable pavement systems relies heavily on the knowledge of the unsaturated hydraulic properties of the construction materials. Although several modeling tools and many laboratory methods already exist in the literature to determine the hydraulic properties of soils, the importance of an accurate materials hydraulic description of the permeable pavement system, is increasingly recognized in the fields of urban hydrology. Thus, the aim of this study is to propose techniques/procedures on how to interpret water flow through the construction system using the HYDRUS model. The overall analysis includes experimental and mathematical procedures for model calibration and validation to assess the suitability of the HYDRUS-2D model to interpret the hydraulic behaviour of a lab-scale permeable pavement system. The system consists of three porous materials: a wear layer of porous concrete blocks, a bedding layers of fine gravel, and a sub-base layer of coarse gravel. The water regime in this system, i.e. outflow at the bottom and water contents in the middle of the bedding layer, was monitored during ten irrigation events of various durations and intensities. The hydraulic properties of porous concrete blocks and fine gravel described by the van Genuchten functions were measured using the clay tank and the multistep outflow experiments, respectively. Coarse gravel properties were set at literature values. In addition, some of the parameters (Ks of the concrete blocks layer, and α, n and Ks of the bedding layer) were optimized with the HYDRUS-2D model from water fluxes and soil water contents measured during irrigation events. The measured and modeled hydrographs were compared using the Nash-Sutcliffe efficiency (NSE) index (varied between 0.95 and 0.99) while the coefficient of determination R2 was used to assess the measured water content versus the modelled water content in the bedding layer (R2 = 0.81 ÷ 0.87) . The
Reverse Flow Routing in a Bayesian Framework Using a GPU-accelerated 2D Shallow Water Model
D'Oria, M.; Ferrari, A.; Mignosa, P.; Tanda, M. G.; Vacondio, R.
2017-12-01
Knowledge of discharge hydrographs in specific sites of natural rivers is important for water resource management, flood frequency analysis, design of structures, etc. Many times, the flood hydrograph is needed in a river section upstream of a monitoring station; here the flood wave differs from the upstream one because of the effects of resistance, channel storage, lateral inflow, etc. Reverse flow routing is a method that allows obtaining hydrographs in upstream ungauged stations using information available at downstream monitored sites. In this study, we propose an inverse procedure, based on a Bayesian Geostatistical Approach, to solve the reverse problem. The upstream flow values over time (parameters) are considered as random variables and a-priori information about the parameters and observations (downstream discharge or water level values) are combined together in a Bayesian framework. The methodology needs a forward model of the considered open channel that includes the upstream ungauged station and the downstream gauged one and it is able to describe, with sufficient accuracy, the hydraulic routing processes. In many real cases, especially when large floodable areas are involved, a 1D hydraulic model is not able to capture the complex river hydrodynamic and a 2D model must be used. The inverse procedure requires a high number of flow model run to linearize the forward problem through multiple evaluations of a Jacobian matrix (sensitivity of each observation to each parameter) using a finite difference approach. For this reason, the computational efficiency of the forward model is a crucial element to reduce the overall computational costs. Therefore, in this work we used, in combination with the inverse procedure, a GPU-parallel numerical model for the solution of the 2D Shallow Water equations (implemented in CUDA/C++ code) that allows achieving ratio of physical to computational time of about 500-1000 (depending on the test case features). In addition
Domej, Gisela; Bourdeau, Céline; Lenti, Luca; Pluta, Kacper
2017-04-01
Landsliding is a worldwide common phenomenon. Every year, and ranging in size from very small to enormous, landslides cause all too often loss of life and disastrous damage to infrastructure, property and the environment. One main reason for more frequent catastrophes is the growth of population on the Earth which entails extending urbanization to areas at risk. Landslides are triggered by a variety and combination of causes, among which the role of water and seismic activity appear to have the most serious consequences. In this regard, seismic shaking is of particular interest since topographic elevation as well as the landslide mass itself can trap waves and hence amplify incoming surface waves - a phenomenon known as "site effects". Research on the topic of landsliding due to seismic and non-seismic activity is extensive and a broad spectrum of methods for modeling slope deformation is available. Those methods range from pseudo-static and rigid-block based models to numerical models. The majority is limited to 2D modeling since more sophisticated approaches in 3D are still under development or calibration. However, the effect of lateral confinement as well as the mechanical properties of the adjacent bedrock might be of great importance because they may enhance the focusing of trapped waves in the landslide mass. A database was created to study 3D landslide geometries. It currently contains 277 distinct seismically and non-seismically triggered landslides spread all around the globe whose rupture bodies were measured in all available details. Therefore a specific methodology was developed to maintain predefined standards, to keep the bias as low as possible and to set up a query tool to explore the database. Besides geometry, additional information such as location, date, triggering factors, material, sliding mechanisms, event chronology, consequences, related literature, among other things are stored for every case. The aim of the database is to enable
Analysis of 2D flow and heat transfer modeling in fracture of porous media
Guo, Chunsheng; Nian, Xianbo; Liu, Yong; Qi, Chao; Song, Jinsheng; Yu, Wenhe
2017-08-01
Heat and mass transfer between porous media and fluid is a complex coupling process, which is widely used in various fields of engineering applications, especially for natural and artificial fractures in oil and gas extraction. In this study, a new method is proposed to deal with the flow and heat transfer problem of steady flow in a fracture. The fluid flow in a fracture was described using the same method as Mohais, who considered a fracture as a channel with porous wall, and the perturbation method was used to solve the mathematical model. Unlike previous studies, the shear jump boundary condition proposed by Ochoa-Tapia and Whitaker was used at the interface between the fluid and porous media. The main methods were perturbation analysis and the application of shear jump boundary conditions. The influence of permeability, channel width, shear jump degree and effective dynamic viscosity on the flow and heat transfer in the channel was studied by analysing the analytical solution. The distribution of axial velocity in the channel with the change of the typical parameters and the sensitivity of the heat transfer was obtained.
Computational study of a magnetic design to improve the diagnosis of malaria: 2D model
Vyas, Siddharth; Genis, Vladimir; Friedman, Gary
2017-02-01
This paper investigates the feasibility of a cost effective high gradient magnetic separation based device for the detection and identification of malaria parasites in a blood sample. The design utilizes magnetic properties of hemozoin present in malaria-infected red blood cells (mRBCs) in order to separate and concentrate them inside a microfluidic channel slide for easier examination under the microscope. The design consists of a rectangular microfluidic channel with multiple magnetic wires positioned on top of and underneath it along the length of the channel at a small angle with respect to the channel axis. Strong magnetic field gradients, produced by the wires, exert sufficient magnetic forces on the mRBCs in order to separate and concentrate them in a specific region small enough to fit within the microscope field of view at magnifications typically required to identify the malaria parasite type. The feasibility of the device is studied using a model where the trajectories of the mRBCs inside the channel are determined using first-order ordinary differential equations (ODEs) solved numerically using a multistep ODE solver available within MATLAB. The mRBCs trajectories reveal that it is possible to separate and concentrate the mRBCs in less than 5 min, even in cases of very low parasitemia (1-10 parasites/μL of blood) using blood sample volumes of around 3 μL employed today.
Process Parameters Optimization of 14nm MOSFET Using 2-D Analytical Modelling
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Noor Faizah Z.A.
2016-01-01
Full Text Available This paper presents the modeling and optimization of 14nm gate length CMOS transistor which is down-scaled from previous 32nm gate length. High-k metal gate material was used in this research utilizing Hafnium Dioxide (HfO2 as dielectric and Tungsten Silicide (WSi2 and Titanium Silicide (TiSi2 as a metal gate for NMOS and PMOS respectively. The devices are fabricated virtually using ATHENA module and characterized its performance evaluation via ATLAS module; both in Virtual Wafer Fabrication (VWF of Silvaco TCAD Tools. The devices were then optimized through a process parameters variability using L9 Taguchi Method. There were four process parameter with two noise factor of different values were used to analyze the factor effect. The results show that the optimal value for both transistors are well within ITRS 2013 prediction where VTH and IOFF are 0.236737V and 6.995705nA/um for NMOS device and 0.248635 V and 5.26nA/um for PMOS device respectively.
2d Falicov-Kimball Model with Correlated Hopping in the Large U Limit
International Nuclear Information System (INIS)
Wojtkiewicz, J.; Lemanski, R.
2001-01-01
Two-dimensional spinless Falicov-Kimball Model (FKM) with a generalized correlated hopping is studied perturbatively in the limit of large on-site Coulomb interaction U. In the half-filled case ( i.e. ρ i +ρ e = 1 , where ρ i ; ρ e are densities of ions and electrons, respectively ,) an effective Hamiltonian in spin variables is derived up to terms proportional to U -3 . Unlike the simplest FKM case, it contains odd parity terms (resulting from the correlated hopping) in addition to even parity ones. The ground-state phase diagram of the effective Hamiltonian is examined in the (a, g, h) parameter space, where a, g are parameters characterizing strength of the correlated hopping and h is a difference of chemical potentials of two sorts of particles present in the system. It appears to be asymmetric with respect to the change h→-h and a new ordered phases are found for certain values of a and g. (author)
Kalisperakis, I.; Stentoumis, Ch.; Grammatikopoulos, L.; Karantzalos, K.
2015-08-01
The indirect estimation of leaf area index (LAI) in large spatial scales is crucial for several environmental and agricultural applications. To this end, in this paper, we compare and evaluate LAI estimation in vineyards from different UAV imaging datasets. In particular, canopy levels were estimated from i.e., (i) hyperspectral data, (ii) 2D RGB orthophotomosaics and (iii) 3D crop surface models. The computed canopy levels have been used to establish relationships with the measured LAI (ground truth) from several vines in Nemea, Greece. The overall evaluation indicated that the estimated canopy levels were correlated (r2 > 73%) with the in-situ, ground truth LAI measurements. As expected the lowest correlations were derived from the calculated greenness levels from the 2D RGB orthomosaics. The highest correlation rates were established with the hyperspectral canopy greenness and the 3D canopy surface models. For the later the accurate detection of canopy, soil and other materials in between the vine rows is required. All approaches tend to overestimate LAI in cases with sparse, weak, unhealthy plants and canopy.
International Nuclear Information System (INIS)
Hill, E.J.; Woehrling, E.K.; Prince, M.; Coleman, M.D.
2008-01-01
Developmental neurotoxicity is a major issue in human health and may have lasting neurological implications. In this preliminary study we exposed differentiating Ntera2/clone D1 (NT2/D1) cell neurospheres to known human teratogens classed as non-embryotoxic (acrylamide), weakly embryotoxic (lithium, valproic acid) and strongly embryotoxic (hydroxyurea) as listed by European Centre for the Validation of Alternative Methods (ECVAM) and examined endpoints of cell viability and neuronal protein marker expression specific to the central nervous system, to identify developmental neurotoxins. Following induction of neuronal differentiation, valproic acid had the most significant effect on neurogenesis, in terms of reduced viability and decreased neuronal markers. Lithium had least effect on viability and did not significantly alter the expression of neuronal markers. Hydroxyurea significantly reduced cell viability but did not affect neuronal protein marker expression. Acrylamide reduced neurosphere viability but did not affect neuronal protein marker expression. Overall, this NT2/D1-based neurosphere model of neurogenesis, may provide the basis for a model of developmental neurotoxicity in vitro
Machado, Vinicius Cunha; Lafuente, Javier; Baeza, Juan Antonio
2014-07-01
The present work developed a model for the description of a full-scale wastewater treatment plant (WWTP) (Manresa, Catalonia, Spain) for further plant upgrades based on the systematic parameter calibration of the activated sludge model 2d (ASM2d) using a methodology based on the Fisher information matrix. The influent was characterized for the application of the ASM2d and the confidence interval of the calibrated parameters was also assessed. No expert knowledge was necessary for model calibration and a huge available plant database was converted into more useful information. The effect of the influent and operating variables on the model fit was also studied using these variables as calibrating parameters and keeping the ASM2d kinetic and stoichiometric parameters, which traditionally are the calibration parameters, at their default values. Such an "inversion" of the traditional way of model fitting allowed evaluating the sensitivity of the main model outputs regarding the influent and the operating variables changes. This new approach is able to evaluate the capacity of the operational variables used by the WWTP feedback control loops to overcome external disturbances in the influent and kinetic/stoichiometric model parameters uncertainties. In addition, the study of the influence of operating variables on the model outputs provides useful information to select input and output variables in decentralized control structures.
Directory of Open Access Journals (Sweden)
Jun Li
2015-02-01
Full Text Available In this work, a macroscopic non-linear constitutive model accounting for damage, inelastic strain and unilateral behavior is proposed for the 2D plain-woven C/SiC composite. A set of scalar damage variables and a new thermodynamic potential expression are introduced in the framework of continuum damage mechanics. In the deduced constitutive equations, the material’s progressive damage deactivation behavior during the compression loading is described by a continuous function, and different deactivation rates under uniaxial and biaxial compression loadings are also considered. In damage evolution laws, the coupling effect among the damage modes and impediment effect of compression stress on the development of shear damage in different plane stress states are taken into account. Besides, the general plasticity theory is applied to describing the evolution of inelastic strain in tension and/or shear stress state. The Tsai–Wu failure criterion is adopted for strength analysis. Additionally, the material model is implemented as a user-defined material subroutine (UMAT and linked to the ABAQUS finite element software, and its performance is demonstrated through several numerical examples.
A 2D hydrodynamic-sedimentological model for gravel-bed rivers. Part I: theory and validation
Directory of Open Access Journals (Sweden)
Gabriel Kaless
2013-09-01
Full Text Available This paper presents a novel 2D-depth average model especially developed for gravel-bed rivers, named Lican-Leufú (Lican=pebble and Leufu=river, in Mapuche’s language, the native inhabitants of Central Patagonia, Argentina. The model consists of three components: a hydrodynamic, a sedimentological, and a morphological model. The flow of water is described by the depth-averaged Reynolds equations for unsteady, free-surface, shallow water flows. It includes the standard k-e model for turbulence closure. Sediment transport can be divided in different size classes (sand-gravel mixture and the equilibrium approach is used for Exner’s equation. The amour layer is also included in the structure of the model and the surface grain size distribution is also allowed to evolve. The model simulates bank slides that enable channel widening. Models predictions were tested against a flume experiment where a static armour layer was developed under conditions of sediment starvations and general good agreements were found: the model predicted adequately the sediment transport, grain size of transported material, final armour grain size distribution and bed elevation.
Renormalizability of the gradient flow in the 2D O(N) non-linear sigma model
Makino, Hiroki; Suzuki, Hiroshi
2015-03-01
It is known that the gauge field and its composite operators evolved by the Yang-Mills gradient flow are ultraviolet (UV) finite without any multiplicative wave function renormalization. In this paper, we prove that the gradient flow in the 2D O(N) non-linear sigma model possesses a similar property: The flowed N-vector field and its composite operators are UV finite without multiplicative wave function renormalization. Our proof in all orders of perturbation theory uses a (2+1)-dimensional field theoretical representation of the gradient flow, which possesses local gauge invariance without gauge field. As an application of the UV finiteness of the gradient flow, we construct the energy-momentum tensor in the lattice formulation of the O(N) non-linear sigma model that automatically restores the correct normalization and the conservation law in the continuum limit.
Directory of Open Access Journals (Sweden)
A. Caserta
1995-06-01
Full Text Available The geological information collected in the last years by the Istituto Nazionale di Geofisica for the city of Rome is used to construct 1- and 2-D models of the nearsurface structure. These models are the basis for the numerical generation of synthetic accelerograms which can simulate the horizontal ground motion (SH waves produced in the different areas of the city by a large (M ? 7 potential earthquake 100 km away in Central Apennines. The proposed methodology yields earthquake engineering parameters (peak ground acceleration and velocity, Arias intensity, energy flux, response spectra whose spatial variations are consistent with the damage distribution caused by the strongest earthquakes felt in Rome during its long history. Based on the macroseismic inforination and the results of the numerical simulations, general criteria for seismic zonation of the city of Rome are proposed.
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Dupré Luc R.
1997-01-01
Full Text Available The main purpose of this paper is to incorporate a refined hysteresis model, viz. a vector Preisach model, in 2D magnetic field computations. To this end the governing Maxwell equations are rewritten in a suitable way, which allows to take into account the proper magnetic material parameters and, moreover, to pass to a variational formulation. The variational problem is solved numerically by a FE approximation, using a quadratic mesh, followed by the time discretisation based upon a modified Cranck Nicholson algorithm. The latter includes a suitable iteration procedure to deal with the nonlinear hysteresis behaviour. Finally, the effectiveness of the presented mathematical tool has been confirmed by several numerical experiments.
Energy Technology Data Exchange (ETDEWEB)
Fialova, M.; Fuerst, J.; Horak, J.; Kozel, K. [Czech Technical Univ., Faculty of Mechanical Engineering, Dept. of Technical Mathematics, Prague (Czech Republic)
1997-12-31
The work deals with numerical solution of 2D and 3D transonic flows using mathematical models of Euler and Navier-Stokes equations. For inviscid flows with a shock wave we tested modern TVD upwind and central methods. For computations of 2D and 3D compressible viscous laminar flows multistage Runge-Kutta methods were used. (orig.)
Hoarau-Véchot, Jessica; Rafii, Arash; Pasquier, Jennifer
2018-01-01
An area that has come to be of tremendous interest in tumor research in the last decade is the role of the microenvironment in the biology of neoplastic diseases. The tumor microenvironment (TME) comprises various cells that are collectively important for normal tissue homeostasis as well as tumor progression or regression. Seminal studies have demonstrated the role of the dialogue between cancer cells (at many sites) and the cellular component of the microenvironment in tumor progression, metastasis, and resistance to treatment. Using an appropriate system of microenvironment and tumor culture is the first step towards a better understanding of the complex interaction between cancer cells and their surroundings. Three-dimensional (3D) models have been widely described recently. However, while it is claimed that they can bridge the gap between in vitro and in vivo, it is sometimes hard to decipher their advantage or limitation compared to classical two-dimensional (2D) cultures, especially given the broad number of techniques used. We present here a comprehensive review of the different 3D methods developed recently, and, secondly, we discuss the pros and cons of 3D culture compared to 2D when studying interactions between cancer cells and their microenvironment. PMID:29346265
Directory of Open Access Journals (Sweden)
Jessica Hoarau-Véchot
2018-01-01
Full Text Available An area that has come to be of tremendous interest in tumor research in the last decade is the role of the microenvironment in the biology of neoplastic diseases. The tumor microenvironment (TME comprises various cells that are collectively important for normal tissue homeostasis as well as tumor progression or regression. Seminal studies have demonstrated the role of the dialogue between cancer cells (at many sites and the cellular component of the microenvironment in tumor progression, metastasis, and resistance to treatment. Using an appropriate system of microenvironment and tumor culture is the first step towards a better understanding of the complex interaction between cancer cells and their surroundings. Three-dimensional (3D models have been widely described recently. However, while it is claimed that they can bridge the gap between in vitro and in vivo, it is sometimes hard to decipher their advantage or limitation compared to classical two-dimensional (2D cultures, especially given the broad number of techniques used. We present here a comprehensive review of the different 3D methods developed recently, and, secondly, we discuss the pros and cons of 3D culture compared to 2D when studying interactions between cancer cells and their microenvironment.
Tiwari, Kumar Anubhav; Raisutis, Renaldas; Mazeika, Liudas; Samaitis, Vykintas
2018-03-26
In this paper, a novel 2D analytical model based on the Huygens's principle of wave propagation is proposed in order to predict the directivity patterns of contact type ultrasonic transducers in the generation of guided waves (GWs). The developed model is able to estimate the directivity patterns at any distance, at any excitation frequency and for any configuration and shape of the transducers with prior information of phase dispersive characteristics of the guided wave modes and the behavior of transducer. This, in turn, facilitates to choose the appropriate transducer or arrays of transducers, suitable guided wave modes and excitation frequency for the nondestructive testing (NDT) and structural health monitoring (SHM) applications. The model is demonstrated for P1-type macro-fiber composite (MFC) transducer glued on a 2 mm thick aluminum (Al) alloy plate. The directivity patterns of MFC transducer in the generation of fundamental guided Lamb modes (the S0 and A0) and shear horizontal mode (the SH0) are successfully obtained at 80 kHz, 5-period excitation signal. The results are verified using 3D finite element (FE) modelling and experimental investigation. The results obtained using the proposed model shows the good agreement with those obtained using numerical simulations and experimental analysis. The calculation time using the analytical model was significantly shorter as compared to the time spent in experimental analysis and FE numerical modelling.
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Kumar Anubhav Tiwari
2018-03-01
Full Text Available In this paper, a novel 2D analytical model based on the Huygens’s principle of wave propagation is proposed in order to predict the directivity patterns of contact type ultrasonic transducers in the generation of guided waves (GWs. The developed model is able to estimate the directivity patterns at any distance, at any excitation frequency and for any configuration and shape of the transducers with prior information of phase dispersive characteristics of the guided wave modes and the behavior of transducer. This, in turn, facilitates to choose the appropriate transducer or arrays of transducers, suitable guided wave modes and excitation frequency for the nondestructive testing (NDT and structural health monitoring (SHM applications. The model is demonstrated for P1-type macro-fiber composite (MFC transducer glued on a 2 mm thick aluminum (Al alloy plate. The directivity patterns of MFC transducer in the generation of fundamental guided Lamb modes (the S0 and A0 and shear horizontal mode (the SH0 are successfully obtained at 80 kHz, 5-period excitation signal. The results are verified using 3D finite element (FE modelling and experimental investigation. The results obtained using the proposed model shows the good agreement with those obtained using numerical simulations and experimental analysis. The calculation time using the analytical model was significantly shorter as compared to the time spent in experimental analysis and FE numerical modelling.
Matsumoto, Atsushi; Miyazaki, Naoyuki; Takagi, Junichi; Iwasaki, Kenji
2017-03-23
In this study, we develop an approach termed "2D hybrid analysis" for building atomic models by image matching from electron microscopy (EM) images of biological molecules. The key advantage is that it is applicable to flexible molecules, which are difficult to analyze by 3DEM approach. In the proposed approach, first, a lot of atomic models with different conformations are built by computer simulation. Then, simulated EM images are built from each atomic model. Finally, they are compared with the experimental EM image. Two kinds of models are used as simulated EM images: the negative stain model and the simple projection model. Although the former is more realistic, the latter is adopted to perform faster computations. The use of the negative stain model enables decomposition of the averaged EM images into multiple projection images, each of which originated from a different conformation or orientation. We apply this approach to the EM images of integrin to obtain the distribution of the conformations, from which the pathway of the conformational change of the protein is deduced.
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Gabriel Kaless
2013-09-01
Full Text Available A 2D depth average model has been used to simulate water and sediment flow in the Brenta River so as to interpret channel changes and to assess model predictive capabilities. The Brenta River is a gravel bed river located in Northern Italy. The study reach is 1400 long and has a mean slope of 0.0056. High resolution digital terrain models has been produced combining laser imaging detection and ranging data with colour bathymetry techniques. Extensive field sedimentological surveys have been also carried out for surface and subsurface material. The data were loaded in the model and the passage of a high intense flood (R.I. > 9 years was simulated. The model was run under the hypothesis of a substantial equilibrium between sediment input and transport capacity. In this way, the model results were considered as a reference condition, and the potential trend of the reach was assessed. Low-frequency floods (R.I. » 1.5 years are expected to produce negligible changes in the channel while high floods may focalize erosion on banks instead than on channel bed. Furthermore, the model predicts well the location of erosion and siltation areas and the results promote its application to other reaches of the Brenta River in order to assess their stability and medium-term evolution.
Calibration model of a dual gain flat panel detector for 2D and 3D x-ray imaging
International Nuclear Information System (INIS)
Schmidgunst, C.; Ritter, D.; Lang, E.
2007-01-01
The continuing research and further development in flat panel detector technology have led to its integration into more and more medical x-ray systems for two-dimensional (2D) and three-dimensional (3D) imaging, such as fixed or mobile C arms. Besides the obvious advantages of flat panel detectors, like the slim design and the resulting optimum accessibility to the patient, their success is primarily a product of the image quality that can be achieved. The benefits in the physical and performance-related features as opposed to conventional image intensifier systems (e.g., distortion-free reproduction of imaging information or almost linear signal response over a large dynamic range) can be fully exploited, however, only if the raw detector images are correctly calibrated and postprocessed. Previous procedures for processing raw data contain idealizations that, in the real world, lead to artifacts or losses in image quality. Thus, for example, temperature dependencies or changes in beam geometry, as can occur with mobile C arm systems, have not been taken into account up to this time. Additionally, adverse characteristics such as image lag or aging effects have to be compensated to attain the best possible image quality. In this article a procedure is presented that takes into account the important dependencies of the individual pixel sensitivity of flat panel detectors used in 2D or 3D imaging and simultaneously minimizes the work required for an extensive recalibration. It is suitable for conventional detectors with only one gain mode as well as for the detectors specially developed for 3D imaging with dual gain read-out technology
Magnetic properties of 2D nano-islands II: Ising spin model with out-of-plane magnetic field
Energy Technology Data Exchange (ETDEWEB)
Abou Ghantous, M., E-mail: michel.aboughantous@qatar.tamu.edu [Department of Physics, Texas A and M University at Qatar, Education City, PO Box 23874, Doha (Qatar); Khater, A. [Laboratoire de Physique de L' Etat Condense, UMR 6087, Universite du Maine, 72085 Le Mans (France)
2011-10-15
An Ising effective field theory model is presented to calculate the magnetic properties of 2D nano-islands on a nonmagnetic substrate, subject to an externally out-of-plane applied magnetic field. The system Hamiltonian contains nearest neighbor exchange interactions, single-atom magnetic anisotropies, and the Zeeman term. The calculations yield, in particular, the single site spin correlations, the magnetizations, and the isothermal susceptibilities, for the core and periphery domains of the nano-island. The choice of a spin S=1 for the atoms of the system permits the analysis of local spin fluctuations via the single site spin correlations. We investigate in this respect the effects due to the different magnetocrystalline anisotropies and reduced dimensionalities, for the core and periphery domains, and in particular the critical influence of the applied magnetic field. Detailed theoretical results are presented for the square and hexagonal lattice symmetries, with numerical applications for the 2D monolayer Co nano-islands on a Pt substrate. It is shown that the remarkable differences between the magnetic properties of the core and periphery domains in zero field are washed out when an out-of-plane field is applied. The applied field also provokes critical discontinuities for the spin correlations and magnetization reversals, for the core and periphery domains, which are especially evident for the hexagonal lattice nano-island in the range of fields of interest. The discontinuities and magnetization reversals occur over elementary temperature widths, and shift to lower temperatures with increasing field. The field-dependant isothermal susceptibilities show new features very different from those for the susceptibilities in zero field. The present Ising model does not show any blocking temperature transition to superparamagnetism. - Highlights: > An EFT model is presented to calculate the magnetic properties of 2D nano-islands. > The Hamiltonian contains n
A 2D double-porosity model for melting and melt migration beneath mid-oceanic ridges
Liu, B.; Liang, Y.; Parmentier, E.
2017-12-01
Several lines of evidence suggest that the melting and melt extraction region of the MORB mantle is heterogeneous consisting of an interconnected network of high permeability dunite channels in a low porosity harzburgite or lherzolite matrix. In principle, one can include channel formation into the tectonic-scale geodynamic models by solving conservation equations for a chemically reactive and viscously deformable porous medium. Such an approach eventually runs into computational limitations such as resolving fractal-like channels that have a spectrum of width. To better understand first order features of melting and melt-rock interaction beneath MOR, we have formulated a 2D double porosity model in which we treat the triangular melting region as two overlapping continua occupied by the low-porosity matrix and interconnected high-porosity channels. We use melt productivity derived from a thermodynamic model and melt suction rate to close our problem. We use a high-order accurate numerical method to solve the conservation equations in 2D for porosity, solid and melt velocities and concentrations of chemical tracers in the melting region. We carry out numerical simulations to systematically study effects of matrix-to-channel melt suction and spatially distributed channels on the distributions of porosity and trace element and isotopic ratios in the melting region. For near fractional melting with 10 vol% channel in the melting region, the flow field of the matrix melt follows closely to that of the solid because the small porosity (exchange between the melt and the solid. The smearing effect can be approximated by dispersion coefficient. For slowly diffusing trace elements (e.g., LREE and HFSE), the melt migration induced dispersion can be as effective as thermal diffusion. Therefore, sub-kilometer scale heterogeneities of Nd and Hf isotopes are significantly damped or homogenized in the melting region.
Ojha, Probir Kumar; Roy, Kunal
2018-02-01
In the present report, we have developed a predictive QSPR model using only easily computable two-dimensional (2D) descriptors from diverse classes of sweetening agents to find out the key structural properties which regulate their sweet potency. The available data set was curated to remove salts, mixtures and compounds without having a definite structure. A k-fold double cross validation technique was employed for variable selection prior to development of the final model. The final model was developed using partial least squares (PLS) regression analysis and selected based on a mean absolute error (MAE) based criteria for the validation sets. The model was validated extensively using different internal and external validation strategies in accordance with the Organization for Economic Co-operation and Development (OECD) guidelines. This work presented development of a validated quantitative structure-property relationship (QSPR) model obtained from k-fold double cross-validation technique in order to find out the key structural information required to enhance the sweet potency of the molecules. Finally, we have designed and proposed 13 new molecules based on the insights obtained from the QSPR model. The designed compounds showed good in silico predicted sweetness potency with acceptable ADMET profile. Copyright © 2017 Elsevier Ltd. All rights reserved.
Zischg, Andreas Paul; Felder, Guido; WWeingartner, Rolf
2015-04-01
The catchment of the river Aare upstream of Bern, Switzerland, with an area of approx. 3000 km2 is a complex network of sub-catchments with different runoff characteristics; it also includes two larger lakes. Most of the rivers were regulated in the 18th century. An important regulation, however, was realised as early as in the 17th century. For this catchment, the worst case flood event was identified and its consequences were analysed. Beside the hydro-meteorological characteristics, an important basis to model the worst case flood is to understand the non-linear effects of flood retention in the valley bottom and in the lakes. The aim of this study was to compare these effects based on both the current river network and the historic one prior to the main river training works. This allows to quantify the human impacts. Methodologically, we set up a coupled 2D flood model representing the floodplains of the river Aare as well as of the tributaries Lombach, Lütschine, Zulg, Rotache, Chise and Guerbe. The flood simulation was made in 2D with the software BASEMENT-ETH (Vetsch et al. 2014). The model was calibrated by means of reproducing the large floods in August 2005 and the bankfull discharge for all river reaches. The model computes the discharge at the outlet of the Aare catchment at Bern by routing all discharges from the sub-catchments through the river reaches and their floodplains. With this, the modulation of the input hydrographs by widespread floodings in the floodplains can be quantified. The same configuration was applied on the basis of reconstructed digital terrain models representing the landscape and the river network before the first significant river training works had been realised. This terrain model was reconstructed by georeferencing and digitalizing historic maps and cross-sections combined with the mapping of the geomorphologic evidences of former river structures in non-modified areas. The latter mapping procedure was facilitated by the
Dages, Cecile; Samouelian, Anatja; Lanoix, Marthe; Dollinger, Jeanne; Chakkour, Sara; Chovelon, Gabrielle; Trabelsi, Khouloud; Voltz, Marc
2015-04-01
Ditches are involved in the transfer of pesticide to surface and groundwaters (e.g. Louchart et al., 2001). Soil horizons underlying ditch beds may present specific soil characteristics compared to neighbouring field soils due to erosion/deposition processes, to the specific biological activities (rooting dynamic and animal habitat) in the ditches (e.g. Vaughan et al., 2008) and to management practices (burning, dredging, mowing,...). Moreover, in contrast to percolation processes in field soils that can be assumed to be mainly 1D vertical, those occurring in the ditch beds are by essence 2D or even 3D. Nevertheless, due to a lake of knowledge, these specific aspects of transfer within ditch beds are generally omitted for hydrological simulation at the catchment scale (Mottes et al., 2014). Accordingly, the aims of this study were i) to characterize subsurface solute transfer through ditch beds and ii) to determine equivalent hydraulic parameters of the ditch beds for use in catchment scale hydrological simulations. A complementary aim was to evaluate the error in predictions performed when percolation in ditches is assumed to be similar to that in the neighbouring field soil. First, bromide transfer experiments were performed on undisturbed soil column (15 cm long with a 15 cm inner-diameter), horizontally and vertically sampled within each soil horizon underlying a ditch bed and within the neighboring field. Columns were sampled at the Roujan catchment (Hérault, France), which belongs to the long term Mediterranean hydrological observatory OMERE (Voltz and Albergel, 2002). Second, for each column, a set of parameters was determined by inverse optimization with mobile-immobile or dual permeability models, with CXTFIT (Toride et al., 1999) or with HYDRUS (Simunek et al., 1998). Third, infiltration and percolation in the ditch was simulated by a 2D flow domain approach considering the 2D variation in hydraulic properties of the cross section of a ditch bed. Last
Directory of Open Access Journals (Sweden)
J. P. McCormack
2006-01-01
Full Text Available The new CHEM2D-Ozone Photochemistry Parameterization (CHEM2D-OPP for high-altitude numerical weather prediction (NWP systems and climate models specifies the net ozone photochemical tendency and its sensitivity to changes in ozone mixing ratio, temperature and overhead ozone column based on calculations from the CHEM2D interactive middle atmospheric photochemical transport model. We evaluate CHEM2D-OPP performance using both short-term (6-day and long-term (1-year stratospheric ozone simulations with the prototype high-altitude NOGAPS-ALPHA forecast model. An inter-comparison of NOGAPS-ALPHA 6-day ozone hindcasts for 7 February 2005 with ozone photochemistry parameterizations currently used in operational NWP systems shows that CHEM2D-OPP yields the best overall agreement with both individual Aura Microwave Limb Sounder ozone profile measurements and independent hemispheric (10°–90° N ozone analysis fields. A 1-year free-running NOGAPS-ALPHA simulation using CHEM2D-OPP produces a realistic seasonal cycle in zonal mean ozone throughout the stratosphere. We find that the combination of a model cold temperature bias at high latitudes in winter and a warm bias in the CHEM2D-OPP temperature climatology can degrade the performance of the linearized ozone photochemistry parameterization over seasonal time scales despite the fact that the parameterized temperature dependence is weak in these regions.
Numerical research of a 2D axial symmetry hybrid model for the radio-frequency ion thruster
Chenchen, WU; Xinfeng, SUN; Zuo, GU; Yanhui, JIA
2018-04-01
Since the high efficiency discharge is critical to the radio-frequency ion thruster (RIT), a 2D axial symmetry hybrid model has been developed to study the plasma evolution of RIT. The fluid method and the drift energy correction of the electron energy distribution function (EEDF) are applied to the analysis of the RIT discharge. In the meantime, the PIC-MCC method is used to investigate the ion beam current extraction character for the plasma plume region. The beam current simulation results, with the hybrid model, agree well with the experimental results, and the error is lower than 11%, which shows the validity of the model. The further study shows there is an optimal ratio for the radio-frequency (RF) power and the beam current extraction power under the fixed RIT configuration. And the beam extraction efficiency will decrease when the discharge efficiency beyond a certain threshold (about 87 W). As the input parameters of the hybrid model are all the design values, it can be directly used to the optimum design for other kinds of RITs and radio-frequency ion sources.
Xie, Q.; Song, G.; Gorti, S.; Stoica, A. D.; Radhakrishnan, B.; Bilheux, J. C.; Kirka, M.; Dehoff, R.; Bilheux, H. Z.; An, K.
2018-02-01
Bragg-edge imaging, which is also known as neutron radiography, has recently emerged as a novel crystalline characterization technique. Modelling of this novel technique by incorporating various features of the underlying microstructure (including the crystallographic texture, the morphological texture, and the grain size) of the material remains a subject of considerable research and development. In this paper, Inconel 718 samples made by additive manufacturing were investigated by neutron diffraction and neutron radiography techniques. The specimen features strong morphological and crystallographic textures and a highly heterogeneous microstructure. A 3D statistical full-field model is introduced by taking details of the microstructure into account to understand the experimental neutron radiography results. The Bragg-edge imaging and the total cross section were calculated based on the neutron transmission physics. A good match was obtained between the model predictions and experimental results at different incident beam angles with respect to the sample build direction. The current theoretical approach has the ability to incorporate 3D spatially resolved microstructural heterogeneity information and shows promise in understanding the 2D neutron radiography of bulk samples. With further development to incorporate the heterogeneity in lattice strain in the model, it can be used as a powerful tool in the future to better understand the neutron radiography data.
Comparing the Discrete and Continuous Logistic Models
Gordon, Sheldon P.
2008-01-01
The solutions of the discrete logistic growth model based on a difference equation and the continuous logistic growth model based on a differential equation are compared and contrasted. The investigation is conducted using a dynamic interactive spreadsheet. (Contains 5 figures.)
Sparks, S. A.; Thigpen, J. R.
2017-12-01
In continental tectonics, questions remain regarding the dominant mechanisms of shortening accommodation during orogen evolution. Two quantitatively-supported models, critical wedge and channel flow, have been applied to the Himalaya and proposed for other large collisional systems. These two models represent fundamentally distinct mechanisms for accommodating shortening in collisional systems and until recently have been viewed as mutually exclusive. While there remains support for these mechanisms being incompatible end-members, in more recent studies it has been proposed that either: (1) both geodynamic mechanisms may operate simultaneously yet in spatially distinct parts of the larger composite orogenic system or (2) both mechanisms are present yet they operate at temporally distinct intervals, wherein the orogen progressively develops through stages dominated by mid-crustal channel flow followed by shallow thrust stacking and duplex development. In both scenarios, the mechanism active at each stage in orogen evolution is presumably dependent upon local to regional scale rheological conditions (as a function of orogen dynamic and thermal evolution) that are likely to be transient in both space and time. However, questions regarding the dynamic, mechanical, and thermal-kinematic relationships of such a system remain. Also, while field observations and deformation records derived from analyses of transects within the Himalaya can be interpreted in such a way to be consistent with a unified model, numerical models that predict the behavior of interactions between the end-member models have - until now - not existed. Here, we present results from 2-D coupled thermomechanical finite-element numerical experiments that examine the necessary conditions for mechanical compatibility between the channel and critical wedge by focusing on the role of rheology. These model results will eventually allow us to make preliminary comparisons between model-derived stress
Directory of Open Access Journals (Sweden)
Shuai-Bing He
2016-10-01
Full Text Available During the past decades, there have been continuous attempts in the prediction of metabolism mediated by cytochrome P450s (CYP450s 3A4, 2D6, and 2C9. However, it has indeed remained a huge challenge to accurately predict the metabolism of xenobiotics mediated by these enzymes. To address this issue, microsomal metabolic reaction system (MMRS—a novel concept, which integrates information about site of metabolism (SOM and enzyme—was introduced. By incorporating the use of multiple feature selection (FS techniques (ChiSquared (CHI, InfoGain (IG, GainRatio (GR, Relief and hybrid classification procedures (Kstar, Bayes (BN, K-nearest neighbours (IBK, C4.5 decision tree (J48, RandomForest (RF, Support vector machines (SVM, AdaBoostM1, Bagging, metabolism prediction models were established based on metabolism data released by Sheridan et al. Four major biotransformations, including aliphatic C-hydroxylation, aromatic C-hydroxylation, N-dealkylation and O-dealkylation, were involved. For validation, the overall accuracies of all four biotransformations exceeded 0.95. For receiver operating characteristic (ROC analysis, each of these models gave a significant area under curve (AUC value >0.98. In addition, an external test was performed based on dataset published previously. As a result, 87.7% of the potential SOMs were correctly identified by our four models. In summary, four MMRS-based models were established, which can be used to predict the metabolism mediated by CYP3A4, 2D6, and 2C9 with high accuracy.
The Moyal momentum algebra applied to θ-deformed 2d conformal models and KdV-hierarchies
International Nuclear Information System (INIS)
Boulahoual, A.; Sedra, M.B.
2002-08-01
The properties of the Das-Popowicz Moyal momentum algebra that we introduce in hep-th/0207242 are reexamined in detail and used to discuss some aspects of integrable models and 2d conformal field theories. Among the results presented we setup some useful convention notations which lead to extract some non trivial properties of the Moyal momentum algebra. We use the particular sub-algebra sl n -Σ-tilde n (0,n) to construct the sl 2 -Liouville conformal model δδ-barΦ=2/θe -1/θΦ and its sl 3 -Toda extension δδ-bar 1 =Ae -1/2θ(Φ 1 +1/2Φ 2 ) and δδ-barΦ 2 =Be -1/2 / θ (Φ 1 +2Φ 2 ) . We also show that the central charge, a la Feigin-Fuchs, associated to the spin-2 conformal current of the θ-Liouville model is given by c θ =(1+24θ 2 ). Moreover, the results obtained for the Das-Popowicz Mm algebra are applied to study systematically some properties of the Moyal KdV and Boussinesq hierarchies generalizing some known results. We also discuss the primarily condition of conformal w θ -currents and interpret this condition as being a dressing gauge symmetry in the Moyal momentum space. Some computations related to the dressing gauge group are explicitly presented. (author)
Multi-scale Model of Residual Strength of 2D Plain Weave C/SiC Composites in Oxidation Atmosphere
Chen, Xihui; Sun, Zhigang; Sun, Jianfen; Song, Yingdong
2017-02-01
Multi-scale models play an important role in capturing the nonlinear response of woven carbon fiber reinforced ceramic matrix composites. In plain weave carbon fiber/silicon carbon (C/SiC) composites, the carbon fibers and interphases will be oxidized at elevated temperature and the strength of the composite will be degraded when oxygen enters micro-cracks formed in the as-produced parts due to the mismatch in thermal properties between constituents. As a result of the oxidation on fiber surface, fiber shows a notch-like morphology. In this paper, the change rule of fiber notch depth is fitted by circular function. And a multi-scale model based upon the change rule of fiber notch depth is developed to simulate the residual strength and post-oxidation stress-strain curves of the composite. The multi-scale model is able to accurately predict the residual strength and post-oxidation stress-strain curves of the composite. Besides, the simulated residual strength and post-oxidation stress-strain curves of 2D plain weave C/SiC composites in oxidation atmosphere show good agreements with experimental results. Furthermore, the oxidation time and temperature of the composite are investigated to show their influences upon the residual strength and post-oxidation stress-strain curves of plain weave C/SiC composites.
International Nuclear Information System (INIS)
Thiery, Mylene; Coustols, Eric
2006-01-01
The present study deals with recent numerical results from on-going research conducted at ONERA/DMAE regarding the prediction of transonic flows, for which shock wave/boundary layer interaction is important. When this interaction is strong enough (M ≥ 1.3), shock induced oscillations (SIO) appear at the suction side of the airfoil and lead to the formation of unsteady separated areas. The main issue is then to perform unsteady computations applying appropriate turbulence modelling and relevant boundary conditions with respect to the test case. Computations were performed with the ONERA elsA software and the URANS-type approach, closure relationships being achieved from transport-equation models. Applications are provided for the OAT15A airfoil data base, well documented for unsteady CFD validation (mean and r.m.s. pressure, phase-averaged LDA data, ...). In this paper, the capabilities of turbulence models are evaluated with two 2D URANS strategies, under free-stream or confined conditions. The latter takes into account the adaptive upper and lower wind-tunnel walls. A complete 3D URANS simulation was then performed to demonstrate the real impact of all lateral wind-tunnel walls on such a flow
Meqbel, Naser; Weckmann, Ute; Muñoz, Gerard; Ritter, Oliver
2016-12-01
We report on a study to explore the deep electrical conductivity structure of the Dead Sea Basin (DSB) using magnetotelluric (MT) data collected along a transect across the DSB where the left lateral strike-slip Dead Sea transform (DST) fault splits into two fault strands forming one of the largest pull-apart basins of the world. A very pronounced feature of our 2-D inversion model is a deep, subvertical conductive zone beneath the DSB. The conductor extends through the entire crust and is sandwiched between highly resistive structures associated with Precambrian rocks of the basin flanks. The high electrical conductivity could be attributed to fluids released by dehydration of the uppermost mantle beneath the DSB, possibly in combination with fluids released by mid- to low-grade metamorphism in the lower crust and generation of hydrous minerals in the middle crust through retrograde metamorphism. Similar high conductivity zones associated with fluids have been reported from other large fault systems. The presence of fluids and hydrous minerals in the middle and lower crust could explain the required low friction coefficient of the DST along the eastern boundary of the DSB and the high subsidence rate of basin sediments. 3-D inversion models confirm the existence of a subvertical high conductivity structure underneath the DSB but its expression is far less pronounced. Instead, the 3-D inversion model suggests a deepening of the conductive DSB sediments off-profile towards the south, reaching a maximum depth of approximately 12 km, which is consistent with other geophysical observations. At shallower levels, the 3-D inversion model reveals salt diapirism as an upwelling of highly resistive structures, localized underneath the Al-Lisan Peninsula. The 3-D model furthermore contains an E-W elongated conductive structure to the northeast of the DSB. More MT data with better spatial coverage are required, however, to fully constrain the robustness of the above
A COUPLED 2 × 2D BABCOCK–LEIGHTON SOLAR DYNAMO MODEL. II. REFERENCE DYNAMO SOLUTIONS
International Nuclear Information System (INIS)
Lemerle, Alexandre; Charbonneau, Paul
2017-01-01
In this paper we complete the presentation of a new hybrid 2 × 2D flux transport dynamo (FTD) model of the solar cycle based on the Babcock–Leighton mechanism of poloidal magnetic field regeneration via the surface decay of bipolar magnetic regions (BMRs). This hybrid model is constructed by allowing the surface flux transport (SFT) simulation described in Lemerle et al. to provide the poloidal source term to an axisymmetric FTD simulation defined in a meridional plane, which in turn generates the BMRs required by the SFT. A key aspect of this coupling is the definition of an emergence function describing the probability of BMR emergence as a function of the spatial distribution of the internal axisymmetric magnetic field. We use a genetic algorithm to calibrate this function, together with other model parameters, against observed cycle 21 emergence data. We present a reference dynamo solution reproducing many solar cycle characteristics, including good hemispheric coupling, phase relationship between the surface dipole and the BMR-generating internal field, and correlation between dipole strength at cycle maximum and peak amplitude of the next cycle. The saturation of the cycle amplitude takes place through the quenching of the BMR tilt as a function of the internal field. The observed statistical scatter about the mean BMR tilt, built into the model, acts as a source of stochasticity which dominates amplitude fluctuations. The model thus can produce Dalton-like epochs of strongly suppressed cycle amplitude lasting a few cycles and can even shut off entirely following an unfavorable sequence of emergence events.
A COUPLED 2 × 2D BABCOCK–LEIGHTON SOLAR DYNAMO MODEL. II. REFERENCE DYNAMO SOLUTIONS
Energy Technology Data Exchange (ETDEWEB)
Lemerle, Alexandre; Charbonneau, Paul, E-mail: lemerle@astro.umontreal.ca, E-mail: paulchar@astro.umontreal.ca [Département de physique, Université de Montréal, 2900 Boulevard Édouard-Montpetit, Montréal, QC, H3T 1J4 (Canada)
2017-01-10
In this paper we complete the presentation of a new hybrid 2 × 2D flux transport dynamo (FTD) model of the solar cycle based on the Babcock–Leighton mechanism of poloidal magnetic field regeneration via the surface decay of bipolar magnetic regions (BMRs). This hybrid model is constructed by allowing the surface flux transport (SFT) simulation described in Lemerle et al. to provide the poloidal source term to an axisymmetric FTD simulation defined in a meridional plane, which in turn generates the BMRs required by the SFT. A key aspect of this coupling is the definition of an emergence function describing the probability of BMR emergence as a function of the spatial distribution of the internal axisymmetric magnetic field. We use a genetic algorithm to calibrate this function, together with other model parameters, against observed cycle 21 emergence data. We present a reference dynamo solution reproducing many solar cycle characteristics, including good hemispheric coupling, phase relationship between the surface dipole and the BMR-generating internal field, and correlation between dipole strength at cycle maximum and peak amplitude of the next cycle. The saturation of the cycle amplitude takes place through the quenching of the BMR tilt as a function of the internal field. The observed statistical scatter about the mean BMR tilt, built into the model, acts as a source of stochasticity which dominates amplitude fluctuations. The model thus can produce Dalton-like epochs of strongly suppressed cycle amplitude lasting a few cycles and can even shut off entirely following an unfavorable sequence of emergence events.
Stephenson, R.; Bocin, A.; Tryggvason, A.
2003-12-01
The DACIA-PLAN (Danube and Carpathian Integrated Action on Processes in the Lithosphere and Neotectonics) deep seismic reflection survey was performed in August-September 2001, with the objective of obtaining of new information on the deep structure of the external Carpathians nappes and the architecture of Tertiary/Quaternary basins developed within and adjacent to the seismically-active Vrancea Zone, including the rapidly subsiding Focsani Basin. The DACIA-PLAN profile is about 140 km long, having a roughly NW-SE direction, from near the southeast Transylvanian Basin, across the mountainous southeastern Carpathians and their foreland to near the Danube Dalta. A high resolution 2D velocity model of the upper crust along the seismic profile has been determined from a first-arrival tomographic inversion of the DACIA-PLAN data. The shallowing of Palaeozoic-Mesozoic basement, and related structural heterogeneity within it, beneath the eastern flank of the Focsani Basin is clearly seen. Velocity heterogeneity within the Carpathian nappe belt is also evident and is indicative of internal structural complexity, including the presence of salt bodies and basement involvement in thrusting, thus favouring some current geological models over others. The presence of basement involvement implies the compressional reactivation of pre-existing basement normal faults. Members of the DACIA-PLAN/TomoSeis Working Group (see poster) should be considered as co-authors of this presentation.
NIR assignment of isopsoralen by 2D-COS technology and model application in Yunkang Oral Liquid
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Yanling Pei
2015-11-01
Full Text Available Near infrared (NIR assignment of Isopsoralen was performed using deuterated chloroform solvent and two-dimensional correlation spectroscopy (2D-COS technology. Yunkang Oral Liquid was applied to study Isopsoralen, the characteristic bands by spectral assignment as well as the bands by interval partial least squares (iPLS and synergy interval partial least squares (siPLS were used to establish partial least squares (PLS model. The coefficient of determination in calibration $(R_{\\rm cal}^{2}$ were 0.9987, 0.9970 and 0.9982. The coefficient of determination in cross validation $(R_{\\rm val}^{2}$ were 0.9985, 0.9921 and 0.9982. The coefficient of determination in prediction $(R_{\\rm pre}^{2}$ were 0.9987, 0.9955 and 0.9988. The root mean square error of calibration (RMSEC were 0.27, 0.40 and 0.31 ppm. The root mean square error of cross validation (RMSECV were 0.30, 0.67 and 0.32 ppm. The root mean square error of prediction (RMSEP were 0.23, 0.43 and 0.22 ppm. The residual predictive deviation (RPD were 31.00, 16.58 and 32.41. It turned out that the characteristic bands by spectral assignment had the same results with the chemometrics methods in PLS model. It provided guidance for NIR spectral assignment of chemical compositions in Chinese Materia Medica (CMM.
Sampson, C. C.; Wing, O.; Quinn, N.; Smith, A.; Neal, J. C.; Schumann, G.; Bates, P.
2017-12-01
During an ongoing natural disaster data are required on: (1) the current situation (nowcast); (2) its likely immediate evolution (forecast); and (3) a consistent view post-event of what actually happened (hindcast or reanalysis). We describe methods used to achieve all three tasks for flood inundation during the Harvey and Irma events using a continental scale 2D hydrodynamic model (Wing et al., 2017). The model solves the local inertial form of the Shallow Water equations over a regular grid of 1 arcsecond ( 30m). Terrain data are taken from the USGS National Elevation Dataset with known flood defences represented using the U.S. Army Corps of Engineers National Levee Dataset. Channels are treated as sub-grid scale features using the HydroSHEDS global hydrography data set. The model is driven using river flows, rainfall and coastal water levels. It simulates river flooding in basins > 50 km2, and fluvial and coastal flooding everywhere. Previous wide area validation tests show this model to be capable of matching FEMA maps and USGS local models built with bespoke data with hit rates of 86% and 92% respectively (Wing et al., 2017). Boundary conditions were taken from NOAA QPS data to produce nowcast and forecast simulations in near real time, before updating with NOAA observations to produce the hindcast. During the event simulation results were supplied to major insurers and multi-nationals who used them to estimate their likely capital exposure and to mitigate flood damage to their infrastructure whilst the event was underway. Simulations were validated against modelled flood footprints computed by FEMA and USACE, and composite satellite imagery produced by the Dartmouth Flood Observatory. For the Harvey event, hit rates ranged from 60-84% against these data sources, but a lack of metadata meant it was difficult to perform like-for-like comparisons. The satellite data also appeared to miss known flooding in urban areas that was picked up in the models. Despite
Multimedia Mapping using Continuous State Space Models
DEFF Research Database (Denmark)
Lehn-Schiøler, Tue
2004-01-01
In this paper a system that transforms speech waveforms to animated faces are proposed. The system relies on continuous state space models to perform the mapping, this makes it possible to ensure video with no sudden jumps and allows continuous control of the parameters in 'face space'. Simulatio...
Elsawy, Hesham
2014-11-01
Device-to-device (D2D) communication enables the user equipments (UEs) located in close proximity to bypass the cellular base stations (BSs) and directly connect to each other, and thereby, offload traffic from the cellular infrastructure. D2D communication can improve spatial frequency reuse and energy efficiency in cellular networks. This paper presents a comprehensive and tractable analytical framework for D2D-enabled uplink cellular networks with a flexible mode selection scheme along with truncated channel inversion power control. The developed framework is used to analyze and understand how the underlaying D2D communication affects the cellular network performance. Through comprehensive numerical analysis, we investigate the expected performance gains and provide guidelines for selecting the network parameters.
An investigation of a new 2D CDM model in predicting failure in HFQing of an automotive panel
Directory of Open Access Journals (Sweden)
Mohamed Mohamed
2015-01-01
Full Text Available In this paper a comparative analysis of failure prediction when using the solution heat treatment cold die forming and quenching process, known as HFQTM, for forming an aluminium alloy AA6082 automotive panel part (bulkhead panel, is presented. An experimental programme has been designed and a series of tests have been carried out to investigate the effect of process parameters on the success of forming the complex-shaped automotive panel component using the high strength aluminium alloy. A set of unified viscoplastic plane-stress continuum damage mechanics (2D-CDM constitutive equations was calibrated for AA6082 over a temperature range of 450 ∘C–525 ∘C and strain rates of 0.1, 1.0 and 10 s−1, and then was integrated into the commercial finite element code, LS-DYNA, via a user-defined material subroutine, UMAT, for the forming process simulation. The results show that the CDM model can be used to provide accurate formability and failure predictions.
International Nuclear Information System (INIS)
Ni Meng
2013-01-01
Highlights: ► A heat and mass transfer model is developed for a compact reformer. ► Hydrogen production from methane steam reforming is simulated. ► Increasing temperature greatly increases the reaction rates at the inlet. ► Temperature in the downstream is increased at higher rate of heat supply. ► Larger permeability enhances gas flow and reaction rates in the catalyst layer. - Abstract: Compact reformers (CRs) are promising devices for efficient fuel processing. In CRs, a thin solid plate is sandwiched between two catalyst layers to enable efficient heat transfer from combustion duct to the reforming duct for fuel processing. In this study, a 2D heat and mass transfer model is developed to investigate the fundamental transport phenomenon and chemical reaction kinetics in a CR for hydrogen production by methane steam reforming (MSR). Both MSR reaction and water gas shift reaction (WGSR) are considered in the numerical model. Parametric simulations are performed to examine the effects of various structural/operating parameters, such as pore size, permeability, gas velocity, temperature, and rate of heat supply on the reformer performance. It is found that the reaction rates of MSR and WGSR are the highest at the inlet but decrease significantly along the reformer. Increasing the operating temperature raises the reaction rates at the inlet but shows very small influence in the downstream. For comparison, increasing the rate of heat supply raises the reaction rates in the downstream due to increased temperature. A high gas velocity and permeability facilitates gas transport in the porous structure thus enhances reaction rates in the downstream of the reformer.
International Nuclear Information System (INIS)
Fradkin, E.S.; Linetsky, V.Ya.
1990-10-01
The irreducible Racah basis for SU(N + 1|N) is introduced. An analytic continuation with respect to N leads to infinite-dimensional superalgebras su(υ + 1|υ). Large υ limit su(∞ + 1|∞) is calculated. The higher spin Sugawara construction leading to generalizations of the Virasoro algebra with infinite tower of higher spin currents is proposed and related WZNW and Toda models as well as possible applications in string theory are discussed. (author). 32 refs
Joseph, Rose; Goorjian, Peter; Taflove, Allen
1993-01-01
Experimentalists have produced all-optical switches capable of 100-fs responses. To adequately model such switches, nonlinear effects in optical materials (both instantaneous and dispersive) must be included. In principle, the behavior of electromagnetic fields in nonlinear dielectrics can be determined by solving Maxwell's equations subject to the assumption that the electric polarization has a nonlinear relation to the electric field. However, until our previous work, the resulting nonlinear Maxwell's equations have not been solved directly. Rather, approximations have been made that result in a class of generalized nonlinear Schrodinger equations (GNLSE) that solve only for the envelope of the optical pulses. In this paper, we present first-time calculations from the vector nonlinear Maxwell's equations of femtosecond soliton propagation and scattering, including carrier waves, in two-dimensional systems of dielectric waveguides exhibiting the Kerr and Raman quantum effects. We use the finite-difference time-domain (FD-TD) method in an extension of our 1-D work. There, in a fundamental innovation, we treated the linear and nonlinear convolutions for the electric polarization as new dependent variables. By differentiating these convolutions in the time domain, we derived an equivalent system of coupled, nonlinear second-order ODE's. These equations together with Maxwell's equations form the system that is solved to determine the electromagnetic fields in inhomogeneous nonlinear dispersive media. Backstorage in time is limited to only that needed by the time-integration algorithm for the ODE's, rather than that needed to store the time-history of the kernel functions of the convolutions (1000-10,000 time steps). Thus, a 2-D nonlinear optics model from Maxwell's equations is now feasible.
International Nuclear Information System (INIS)
Lanaro, Flavio; Sato, Toshinori; Funato, Akio
2008-01-01
Numerical scooping calculations by means of FRACOD 2D had shown that Brazilian test models present a bend in the relation between the sample deformation perpendicularly to the loading direction and the load itself. The input 'direct' tensile strength of the rock could be re-obtained based on the numerical load at the bend. In this study, a similar technique is applied to specially designed Brazilian tests on Toki granite (Gifu, Japan) which also exhibits such bend for a tensile stress in the centre of the samples of about 2.6 MPa. However, the samples show a wide range of Brazilian tensile strengths that appear to be negatively correlated to the level of in-situ stress at the depth where the samples were taken. The correlation was interpreted as an effect of sample damage due to drilling in a stressed rock mass. Numerical models were designed with various preexist ent crack patterns to simulate the sample damage. The numerical results show Brazilian peak strength results ranging between 6.7 and 13.0 MPa, which are very realistic considering that the laboratory Brazilian tensile strength was observed to vary between 4.1 and 11.3 MPa. These values are all larger than the stress at the bend which is then interpreted as the tensile strength of the weakest grains in the granite. It is also shown that the occurrence of newly initiated cracks at the bend completely changes the stress distribution and failure mechanism of the samples: this explains why the Brazilian tensile strength should be higher than the 'direct' tensile strength of the rock from uniaxial tests. (author)
Chevalier, Laure; Collombet, Marielle; Pinel, Virginie
2017-03-01
Understanding magma degassing evolution during an eruption is essential to improving forecasting of effusive/explosive regime transitions at andesitic volcanoes. Lava domes frequently form during effusive phases, inducing a pressure increase both within the conduit and within the surrounding rocks. To quantify the influence of dome height on magma flow and degassing, we couple magma and gas flow in a 2D numerical model. The deformation induced by magma flow evolution is also quantified. From realistic initial magma flow conditions in effusive regime (Collombet, 2009), we apply increasing pressure at the conduit top as the dome grows. Since volatile solubility increases with pressure, dome growth is then associated with an increase in magma dissolved water content at a given depth, which corresponds with a decrease in magma porosity and permeability. Magma flow evolution is associated with ground deflation of a few μrad in the near field. However this signal is not detectable as it is hidden by dome subsidence (a few mrad). A Darcy flow model is used to study the impact of pressure and permeability conditions on gas flow in the conduit and surrounding rock. We show that dome permeability has almost no influence on magma degassing. However, increasing pressure in the surrounding rock, due to dome loading, as well as decreasing magma permeability in the conduit limit permeable gas loss at the conduit walls, thus causing gas pressurization in the upper conduit by a few tens of MPa. Decreasing magma permeability and increasing gas pressure increase the likelihood of magma explosivity and hazard in the case of a rapid decompression due to dome collapse.
Energy Technology Data Exchange (ETDEWEB)
Begis, J.; Balzer, G.
1997-02-01
The numerical modelling of internal CFB boilers flows faced with complex phenomenons due to the flows un-stationariness, the heterogeneousness of the particle size distribution, and interactions between the two phases and the walls. Our study consisted in applying numerical models to the experimental configuration of cold circulating fluidized bed studied at the Cerchar. Special attention was given to the analysis of particles - wall interactions models, stemming from Jenkins (1992) and Louge`s (1994) theories, as well as the influence of the particles on fluid turbulence. In order to realize numerical simulations, we have used Eulerian two-phases flow codes developed at NHL medolif(2D), ESTET-ASTRID(3D). From different tests we have deducted that the most appropriate model for the realization of CFB`s prediction is the model taking in account the influence of particles on fluid turbulence. Then, to evaluate the validity limits of this model, we have built the regime diagram, and we have compared it with the experimental diagram. We have concluded that the simulation allows to describe the different CFB`s working regimes, and especially transitions. We have also noticed the importance of the choice of the mean diameter of the simulated particles. In this way, making a correction of the simulated particles` diameter in comparison with Sauter mean particle diameter, we obtained numerical results in good agreement with experimental data. (authors) 13 refs.
Lee, Hyunna; Shim, Hackjoon; Chang, Hyuk-Jae
2015-01-01
This study aimed to propose an intensity-vesselness Gaussian mixture model (IVGMM) tracking for 2D + t segmentation of coronary arteries for X-ray angiography (XA) image sequences. We compose a two dimensional (2D) feature vector of intensity and vesselness to characterize the Gaussian mixture models. In our IVGMM tracking, vessel segmentation is performed for each image frame based on these vessel and background IVGMMs and then the segmentation results of the current image frame is used to update these IVGMMs. The 2D + t segmentation of coronary arteries over the 2D XA image sequence is solved by means of iterating two processes, i.e., segmentation of coronary arteries and update of the IVGMMs. The performance of the proposed IVGMM tracking was evaluated using clinical 2D XA datasets. We evaluated the segmentation accuracy of the IVGMM tracking by comparing with two previous 2D vessel segmentation methods and seven background subtraction (BGS) methods. Of the ten segmentation methods, IVGMM tracking shows the highest similarity to the manual segmentation in terms of precision, recall, Jaccard index (JI), F1 score, and peak signal-to-noise ratio (PSNR). It is concluded that the IVGMM tracking could obtain reasonable segmentation accuracy outperforming conventional vessel enhancement methods and object tracking methods.
A 2-D process-based model for suspended sediment dynamics: A first step towards ecological modeling
Achete, F. M.; van der Wegen, M.; Roelvink, D.; Jaffe, B.
2015-01-01
In estuaries suspended sediment concentration (SSC) is one of the most important contributors to turbidity, which influences habitat conditions and ecological functions of the system. Sediment dynamics differs depending on sediment supply and hydrodynamic forcing conditions that vary over space and over time. A robust sediment transport model is a first step in developing a chain of models enabling simulations of contaminants, phytoplankton and habitat conditions. This works aims to determine turbidity levels in the complex-geometry delta of the San Francisco estuary using a process-based approach (Delft3D Flexible Mesh software). Our approach includes a detailed calibration against measured SSC levels, a sensitivity analysis on model parameters and the determination of a yearly sediment budget as well as an assessment of model results in terms of turbidity levels for a single year, water year (WY) 2011. Model results show that our process-based approach is a valuable tool in assessing sediment dynamics and their related ecological parameters over a range of spatial and temporal scales. The model may act as the base model for a chain of ecological models assessing the impact of climate change and management scenarios. Here we present a modeling approach that, with limited data, produces reliable predictions and can be useful for estuaries without a large amount of processes data.
A 2-D process-based model for suspended sediment dynamics: a first step towards ecological modeling
Achete, F. M.; van der Wegen, M.; Roelvink, D.; Jaffe, B.
2015-06-01
In estuaries suspended sediment concentration (SSC) is one of the most important contributors to turbidity, which influences habitat conditions and ecological functions of the system. Sediment dynamics differs depending on sediment supply and hydrodynamic forcing conditions that vary over space and over time. A robust sediment transport model is a first step in developing a chain of models enabling simulations of contaminants, phytoplankton and habitat conditions. This works aims to determine turbidity levels in the complex-geometry delta of the San Francisco estuary using a process-based approach (Delft3D Flexible Mesh software). Our approach includes a detailed calibration against measured SSC levels, a sensitivity analysis on model parameters and the determination of a yearly sediment budget as well as an assessment of model results in terms of turbidity levels for a single year, water year (WY) 2011. Model results show that our process-based approach is a valuable tool in assessing sediment dynamics and their related ecological parameters over a range of spatial and temporal scales. The model may act as the base model for a chain of ecological models assessing the impact of climate change and management scenarios. Here we present a modeling approach that, with limited data, produces reliable predictions and can be useful for estuaries without a large amount of processes data.
International Nuclear Information System (INIS)
Gabriel, F.; Escuriol, Y.; Dabbene, F.; Salavy, J.F.; Giancarli, L.; Gastaldi, O.
2006-01-01
As the Tritium self sufficiency is one of the major challenges for fusion reactor, breeding blankets represent one of the major technological breakthroughs required from passing from ITER to the next step reactor, usually called DEMO. One of the two blanket concepts developed in the EU is the Helium Cooled Lithium Lead (HCLL) blanket which uses the eutectic Pb-15.7Li metal liquid as both breeder and neutron multiplier. The structures, made of EUROFER, a low activation ferritic martensitic steel, are cooled by pressurized helium at 8 MPa and inlet/outlet temperature 300/500 o C. In this concept, the LiPb is fed from the top of the blanket and distributed in parallel vertical channels among pairs of cells (one cell for the radial movement towards the plasma, the other for the return). The liquid metal fills the in-box volume and is slowly re-circulated (few mm per seconds) to remove the produced tritium. In this paper, a local finite element modelling of the tritium permeation rate through the HCLL breeder unit cooling plates is presented. The tritium concentration in the helium circuit and remaining in the lithium lead circuit are evaluated by solving partial differential equations governing the tritium concentration balance, the thermal field and the lithium lead velocity field for a simplified 2D geometrical representation of the breeder unit. This allows estimating the sensitivity effect of coupling these different equations in order to deduce a relevant but simplified modelling for tritium permeation. This is to compare with tritium inventories studies, were the tritium permeation rate is estimated using simplified analytical modelling which generally leads to over estimate the tritium permeation rate to the coolant and so has strong influence on the coolant purification plant design. The finite element modelling performed shows that the Tritium permeation is considerable lower than the one obtained in previous estimations where nominal values of the governing
A Continuous Improvement Capital Funding Model.
Adams, Matt
2001-01-01
Describes a capital funding model that helps assess facility renewal needs in a way that minimizes resources while maximizing results. The article explains the sub-components of a continuous improvement capital funding model, including budgeting processes for finish renewal, building performance renewal, and critical outcome. (GR)
Choquard, Ph.; Vuffray, M.
2014-10-01
The coupling between dilatation and vorticity, two coexisting and fundamental processes in fluid dynamics (Wu et al., 2006, pp. 3, 6) is investigated here, in the simplest cases of inviscid 2D isotropic Burgers and pressureless Euler-Coriolis fluids respectively modeled by single vortices confined in compressible, local, inertial and global, rotating, environments. The field equations are established, inductively, starting from the equations of the characteristics solved with an initial Helmholtz decomposition of the velocity fields namely a vorticity free and a divergence free part (Wu et al., 2006, Sects. 2.3.2, 2.3.3) and, deductively, by means of a canonical Hamiltonian Clebsch like formalism (Clebsch, 1857, 1859), implying two pairs of conjugate variables. Two vector valued fields are constants of the motion: the velocity field in the Burgers case and the momentum field per unit mass in the Euler-Coriolis one. Taking advantage of this property, a class of solutions for the mass densities of the fluids is given by the Jacobian of their sum with respect to the actual coordinates. Implementation of the isotropy hypothesis entails a radial dependence of the velocity potentials and of the stream functions associated to the compressible and to the rotational part of the fluids and results in the cancellation of the dilatation-rotational cross terms in the Jacobian. A simple expression is obtained for all the radially symmetric Jacobians occurring in the theory. Representative examples of regular and singular solutions are shown and the competition between dilatation and vorticity is illustrated. Inspired by thermodynamical, mean field theoretical analogies, a genuine variational formula is proposed which yields unique measure solutions for the radially symmetric fluid densities investigated. We stress that this variational formula, unlike the Hopf-Lax formula, enables us to treat systems which are both compressible and rotational. Moreover in the one
Galanti, Giorgio; Pedrizzetti, Gianni; Pedri, Stefano; Stefani, Laura
2017-12-01
Prevention strategies are important to optimize and to manage heart care in breast cancer survivors. Regular physical activity at moderate intensity is normally proposed to maintain myocardial performance; however, no data is available about the different impact of different levels of physical exercise. 2D speckle tracking echocardiography (2DSTE) is an accepted method for early detection of myocardial dysfunction. The study aims to monitor the cardiac performances in breast cancer survivors by 2DSTE analysis to manage sports activity vs physical activity. Two groups of previous breast cancer survivors (33 BCS) trained at moderate intensity and 55 athletes practicing dragon boat (DBA) sport were enrolled. They were matched with two healthy subjects groups: 23 competitive female athletes practicing different sports and 20 healthy women trained with exercise as prescription model. All women were studied by a complete echo examination including LV global longitudinal strain (GLS) assessment (XStrain-Esaote). EF and GS are only significantly higher in healthy subjects (-25.4 ± 2.1). Nevertheless, GLS values are within the normal range for all groups. Particularly, GS does not show any significant differences among subjects (-19.93 ± 4) practicing exercise as prescription when compared to the DBA competitive trained group. 2DSTE method is an appropriate method to supervise the intensity of exercise in breast cancer patients. Particularly, GLS can optimize and improve cancer therapy supporting and creating efficiencies within the health system confirming the role of the exercise prescription therapy in maintaining normal heart function.
Continuous Competence Development Model for Teacher Teams
DEFF Research Database (Denmark)
Weitze, Charlotte Lærke
2014-01-01
"This paper presents the development of the IT‐Pedagogical Think Tank for Teacher Teams (ITP4T), a continuous competence development model. The model was co‐designed following a design‐based research approach with teachers from VUC Storstrøm’s (VUC) Global Classroom (GC), an innovative hybrid...... to create their own continuous competence development. This article describes how and why the different components of the model were developed in response to the teachers’ challenges. Such challenges included lack of time, competence and support from the educational organisation to innovate learning design...
DEFF Research Database (Denmark)
Zwisler, Stine T; Enggaard, Thomas P; Noehr-Jensen, Lene
2009-01-01
Oxycodone is O-demethylated by CYP2D6 to oxymorphone which is a potent micro-receptor agonist. The CYP2D6 oxidation polymorphism divides the Caucasian population in two phenotypes: approximately 8% with no enzyme activity, poor metabolizers (PM) and the remainder with preserved CYP2D6 activity...... including 33 (16 EM and 17 PM) healthy volunteers. Pain tests were performed before and 1, 2, 3 and 4 hr after medication and included pain detection and tolerance thresholds to single electrical sural nerve stimulation, pain summation threshold to repetitive electrical sural nerve stimulation and the cold...... = 0.037, a difference of 10%, CI: 1%-20%) for PM compared with EM. In the cold pressor test, there was less reduction in pain AUC on oxycodone for PM compared with EM (14% vs. 26%, P = 0.012, a difference of 12%, CI: 3%-22%). The plasma oxymorphone/oxycodone ratio was significantly lower in PM...
Directory of Open Access Journals (Sweden)
Longbiao Li
2016-05-01
Full Text Available In this paper, the cyclic fatigue hysteresis loops of 2D woven SiC/SiC ceramic matrix composites (CMCs at elevated temperatures in steam have been investigated. The interface slip between fibers and the matrix existing in matrix cracking modes 3 and 5, in which matrix cracking and interface debonding occurred in longitudinal yarns, is considered as the major reason for hysteresis loops of 2D woven CMCs. The hysteresis loops of 2D SiC/SiC composites corresponding to different peak stresses, test conditions, and loading frequencies have been predicted using the present analysis. The damage parameter, i.e., the proportion of matrix cracking mode 3 in the entire matrix cracking modes of the composite, and the hysteresis dissipated energy increase with increasing fatigue peak stress. With increasing cycle number, the interface shear stress in the longitudinal yarns decreases, leading to transition of interface slip types of matrix cracking modes 3 and 5.
Generalized continuous linear model of international trade
Directory of Open Access Journals (Sweden)
Kostenko Elena
2014-01-01
Full Text Available The probability-based approach to the linear model of international trade based on the theory of Markov processes with continuous time is analysed. A generalized continuous model of international trade is built, in which the transition of the system from state to state is described by linear differential equations. The methodology of how to obtain the intensity matrices, which are differential in nature, is shown, and the same is done for their corresponding transition matrices for processes of purchasing and selling. In the process of the creation of the continuous model, functions and operations of matrices were used in addition to the Laplace transform, which gave the analytical form of the transition matrices, and therefore the expressions for the state vectors of the system. The obtained expressions simplify analysis and calculations in comparison to other methods. The values of the continuous transition matrices include in themselves the results of discrete model of international trade at moments in time proportional to the time step. The continuous model improves the quality of planning and the effectiveness of control of international trade agreements.
Energy Technology Data Exchange (ETDEWEB)
Datta, Robin N. [Bechtel SAlC Company, Las Vegas (US)] (comp.)
2005-02-15
Task 2D concerns numerical simulation of the coupled THC modeling of the DST test at Yucca mountain, with given results for geologic, thermal, hydrologic, mineralogic and petrologic characterization, as-built configuration of the test block of DST, including locations of various sensors and measuring instruments and the plans for heating and cooling, including expected heater powers at various times, and compared with geochemical measurements performed on gas, water, and mineral samples collected from the DST. Two teams of DOE/LBNL (USA) and JNC (Japan) participated the task with different approaches. The LBNL model represented the fractures and rock matrix by a dual-continuum concept, with the mineral-water-gas reactions treated by primarily kinetic and a few equilibrium reactions. The JNC model represented the fractures and matrix as a single effective continuum, with equilibrium mineral-water reactions controlling the chemical evolution (as well as considering aqueous species transport). The JNC team performed the coupled THC simulation of the Yucca Mountain Drift Scale Test by the coupled THM code 'THAMES', mass transport code 'Dtransu' and geochemical code 'PHREEQE' under coupling system code 'COUPLYS'. The LBNL team simulated the THC processes include coupling between heat, water, and vapor flow; aqueous and gaseous species transport; kinetic and equilibrium mineral-water reactions; and feedback of mineral precipitation/dissolution on porosity, permeability, and capillary pressure, with the FDM code TOUGHREACT V3.0. In general, both models capture the temperature evolution in the rock fairly well, although the JNC model yielded a closer match to the initial temperature rise in the rock, probably due to the better site-specific thermal data. Both models showed the contrasting solubility effects of increasing temperature on calcite and silica solubility; yet the dual continuum approach better represented the effects of
International Nuclear Information System (INIS)
Datta, Robin N.
2005-02-01
Task 2D concerns numerical simulation of the coupled THC modeling of the DST test at Yucca mountain, with given results for geologic, thermal, hydrologic, mineralogic and petrologic characterization, as-built configuration of the test block of DST, including locations of various sensors and measuring instruments and the plans for heating and cooling, including expected heater powers at various times, and compared with geochemical measurements performed on gas, water, and mineral samples collected from the DST. Two teams of DOE/LBNL (USA) and JNC (Japan) participated the task with different approaches. The LBNL model represented the fractures and rock matrix by a dual-continuum concept, with the mineral-water-gas reactions treated by primarily kinetic and a few equilibrium reactions. The JNC model represented the fractures and matrix as a single effective continuum, with equilibrium mineral-water reactions controlling the chemical evolution (as well as considering aqueous species transport). The JNC team performed the coupled THC simulation of the Yucca Mountain Drift Scale Test by the coupled THM code 'THAMES', mass transport code 'Dtransu' and geochemical code 'PHREEQE' under coupling system code 'COUPLYS'. The LBNL team simulated the THC processes include coupling between heat, water, and vapor flow; aqueous and gaseous species transport; kinetic and equilibrium mineral-water reactions; and feedback of mineral precipitation/dissolution on porosity, permeability, and capillary pressure, with the FDM code TOUGHREACT V3.0. In general, both models capture the temperature evolution in the rock fairly well, although the JNC model yielded a closer match to the initial temperature rise in the rock, probably due to the better site-specific thermal data. Both models showed the contrasting solubility effects of increasing temperature on calcite and silica solubility; yet the dual continuum approach better represented the effects of the boiling and condensation periods on
Plesniak, Daniel H.; Bulusu, Kartik V.; Plesniak, Michael W.
2012-11-01
Interpretation of complex flow patterns observed in this study of a model curved artery required characterization of multiple, low-circulation secondary flow structures that were observed during the late systolic deceleration and diastolic phases under physiological inflow conditions. Phase-locked, planar vorticity PIV data were acquired at various cross-sectional locations of the 180-degree bent tube model. High circulation, deformed Dean- and Lyne-type vortices were observed during early stages of deceleration, while several smaller scale, highly deformed, low-circulation vortical patterns appeared in the core and near-wall regions during late systolic deceleration and diastolic phases. Due to the multiplicity of vortical scales and shapes, anisotropic 2D Ricker wavelets were used for coherent structure detection in a continuous wavelet transform algorithm (PIVlet 1.2). Our bio-inspired study is geared towards understanding whether optimizing the shape of the wavelet kernel will enable better resolution of several low-circulation, multi-scale secondary flow morphologies and whether new insights into the dynamics of arterial secondary flow structures can accordingly be gained. Supported by the National Science Foundation, Grant No. CBET-0828903 and GW Center for Biomimetics and Bioinspired Engineering (COBRE).
A 2-D FEM thermal model to simulate water flow in a porous media: Campi Flegrei caldera case study
Directory of Open Access Journals (Sweden)
V. Romano
2012-05-01
Full Text Available Volcanic and geothermal aspects both exist in many geologically young areas. In these areas the heat transfer process is of fundamental importance, so that the thermal and fluid-dynamic processes characterizing a viscous fluid in a porous medium are very important to understand the complex dynamics of the these areas. The Campi Flegrei caldera, located west of the city of Naples, within the central-southern sector of the large graben of Campanian plain, is a region where both volcanic and geothermal phenomena are present. The upper part of the geothermal system can be considered roughly as a succession of volcanic porous material (tuff saturated by a mixture formed mainly by water and carbon dioxide. We have implemented a finite elements approach in transient conditions to simulate water flow in a 2-D porous medium to model the changes of temperature in the geothermal system due to magmatic fluid inflow, accounting for a transient phase, not considered in the analytical solutions and fluid compressibility. The thermal model is described by means of conductive/convective equations, in which we propose a thermal source represented by a parabolic shape function to better simulate an increase of temperature in the central part (magma chamber of a box, simulating the Campi Flegrei caldera and using more recent evaluations, from literature, for the medium's parameters (specific heat capacity, density, thermal conductivity, permeability. A best-fit velocity for the permeant is evaluated by comparing the simulated temperatures with those measured in wells drilled by Agip (Italian Oil Agency in the 1980s in the framework of geothermal exploration. A few tens of days are enough to reach the thermal steady state, showing the quick response of the system to heat injection. The increase in the pressure due to the heat transport is then used to compute ground deformation, in particular the vertical displacements characteristics of the Campi Flegrei caldera
Study of flow around model of cooling tower by means of 2D Particle Image Velocimetry measurement
Directory of Open Access Journals (Sweden)
Barraclough Veronika
2017-01-01
Full Text Available This paper deals with flow around a bluff body of hyperboloid shape. It combines results gathered in the course of research by means of Particle Image Velocimetry (PIV. The experiments were carried out by means of low-frequency 2D PIV and the Reynolds number was 43 000.
DEFF Research Database (Denmark)
Doltra, Jordi; Nuñoz, P
2010-01-01
Two different modeling approaches were used to simulate the N leached during an intensively fertigated crop rotation: a recently developed crop-based simulation model (EU-Rotate_N) and a widely recognized solute transport model (Hydrus-2D). Model performance was evaluated using data from an exper......-scaling the quantification of N leaching from a field level to regional and national levels, identifying best management strategies in relation to N use from an environmental and economic perspective...
Humer, Günter; Reithofer, Andreas
2016-04-01
Using an extended 2D hydrodynamic model for evaluating damage risk caused by extreme rain events: Flash-Flood-Risk-Map (FFRM) Upper Austria Considering the increase in flash flood events causing massive damage during the last years in urban but also rural areas [1-4], the requirement for hydrodynamic calculation of flash flood prone areas and possible countermeasures has arisen to many municipalities and local governments. Besides the German based URBAS project [1], also the EU-funded FP7 research project "SWITCH-ON" [5] addresses the damage risk caused by flash floods in the sub-project "FFRM" (Flash Flood Risk Map Upper Austria) by calculating damage risk for buildings and vulnerable infrastructure like schools and hospitals caused by flash-flood driven inundation. While danger zones in riverine flooding are established as an integral part of spatial planning, flash floods caused by overland runoff from extreme rain events have been for long an underrated safety hazard not only for buildings and infrastructure, but man and animals as well. Based on the widespread 2D-model "hydro_as-2D", an extension was developed, which calculates the runoff formation from a spatially and temporally variable precipitation and determines two dimensionally the land surface area runoff and its concentration. The conception of the model is to preprocess the precipitation data and calculate the effective runoff-volume for a short time step of e.g. five minutes. This volume is applied to the nodes of the 2D-model and the calculation of the hydrodynamic model is started. At the end of each time step, the model run is stopped, the preprocessing step is repeated and the hydraulic model calculation is continued. In view of the later use for the whole of Upper Austria (12.000 km²) a model grid of 25x25 m² was established using digital elevation data. Model parameters could be estimated for the small catchment of river Ach, which was hit by an intense rain event with up to 109 mm per hour
Garrote, J.; Alvarenga, F. M.; Díez-Herrero, A.
2016-10-01
The village of Pajares de Pedraza (Segovia, Spain) is located in the floodplain of the Cega River, a left bank tributary of the Douro River. Repeated flash flood events occur in this small village because of its upstream catchment area, mountainous character and impermeable lithology, which reduce concentration time to just a few hours. River overbank flow has frequently caused flooding and property damage to homes and rural properties, most notably in 1927, 1991, 1996, 2001, 2013 and 2014. Consequently, a detailed analysis was carried out to quantify the economic risk of flash floods in peri-urban and rural areas. Magnitudes and exceedance probabilities were obtained from a flood frequency analysis of maximum discharges. To determine the extent and characteristics of the flooded area, we performed 2D hydraulic modeling (Iber 2.0 software) based on LIDAR (1 m) topography and considering three different scenarios associated with the initial construction (1997) and subsequent extension (2013) of a linear defense structure (rockfill dike or levee) to protect the population. Specific stage-damage functions were expressly developed using in situ data collection for exposed elements, with special emphasis on urban-type categories. The average number of elements and their unit value were established. The relationship between water depth and the height at which electric outlets, furniture, household goods, etc. were located was analyzed; due to its effect on the form of the function. Other nonspecific magnitude-damage functions were used in order to compare both economic estimates. The results indicate that the use of non-specific magnitude-damage functions leads to a significant overestimation of economic losses, partly linked to the use of general economic cost data. Furthermore, a detailed classification and financial assessment of exposed assets is the most important step to ensure a correct estimate of financial losses. In both cases, this should include a
Sukhinov, Alexander; Chistyakov, Alexander; Alekseenko, Elena; Roux, Bernard; Chen, Paul Gang; Kharif, Christian
2014-05-01
A special place in terms of complexity and practical significance belongs to the processes associated with transport of sediments in coastal aquatic systems. Coastal dynamics and coastal bottom topography are largely determined by the nature of sediment transport in the coastal zone under the influence of waves and currents. In this work we concider a spatially two-dimensional model of sediment transport, taking into account the following physical parameters and processes: soil porosity, the critical shear stress at which sediment begins moving, turbulent exchange, dynamically changing geometry and function of the bottom elevation level, wind induced currents, bottom shear. Concidered sediment transport model coupled with 2D and 3D models of hydrodynamics Azov3D and implemented on a high performance machine. One of the main feature is that the built discrete model is absolutely stable and completely conservative, in particular, satisfies the law of mass conservation. The coupled model is numerically implemented on the basis of the pressure correction method taking into account nonhydrostatic approximation using the three equations of motion that allows to more adequately describe the hydrodynamic processes near the coastline and on the basis of finite volume method that uses a function of partially filled cells. Results of numerical experiments allow to analyze the dynamics of changes in the bottom geometry, structures and sediment formation, suspension transport, to predict the occurrence of marine ridges and their growth and transformation, to predict the change of the concentration field in the case of emissions from a source, and to predict siltage of navigable channels. The developed on the basis of the parallel programs for high performance system of SFedU model was applied to study the consequences of the naval channel digging in the docks of Arkhangelsk terminal.
Dissipative Continuous Spontaneous Localization (CSL) model.
Smirne, Andrea; Bassi, Angelo
2015-08-05
Collapse models explain the absence of quantum superpositions at the macroscopic scale, while giving practically the same predictions as quantum mechanics for microscopic systems. The Continuous Spontaneous Localization (CSL) model is the most refined and studied among collapse models. A well-known problem of this model, and of similar ones, is the steady and unlimited increase of the energy induced by the collapse noise. Here we present the dissipative version of the CSL model, which guarantees a finite energy during the entire system's evolution, thus making a crucial step toward a realistic energy-conserving collapse model. This is achieved by introducing a non-linear stochastic modification of the Schrödinger equation, which represents the action of a dissipative finite-temperature collapse noise. The possibility to introduce dissipation within collapse models in a consistent way will have relevant impact on the experimental investigations of the CSL model, and therefore also on the testability of the quantum superposition principle.
Thriving in Partnership: Models for Continuing Education
Moroney, Peter; Boeck, Deena
2012-01-01
This article, based on a presentation at the University Professional and Continuing Education Association Annual Conference, March 29, 2012, provides concepts, terminology, and financial models for establishing and maintaining successful institutional partnerships. The authors offer it as a contribution to developing a wider understanding of the…
Goel, Ekta; Singh, Kunal; Singh, Balraj; Kumar, Sanjay; Jit, Satyabrata
2017-09-01
In this paper, the subthreshold behavior of ion-implanted strained-Si double-material double-gate (DMDG) MOSFETs has been analyzed by means of subthreshold current and subthreshold swing. The surface potential based formulation of subthreshold current and subthreshold swing is done by solving the 2-D Poisson's equations in the channel region using parabolic approximation method. The dependence of subthreshold characteristics on various device parameters such as gate length ratio, Ge mole fraction, peak doping concentration, projected range, straggle parameter etc. has been studied. The modeling results are found to be well matched with the simulation data obtained by a 2-D device simulator, ATLAS™, from SILVACO.
Continuous utility factor in segregation models.
Roy, Parna; Sen, Parongama
2016-02-01
We consider the constrained Schelling model of social segregation in which the utility factor of agents strictly increases and nonlocal jumps of the agents are allowed. In the present study, the utility factor u is defined in a way such that it can take continuous values and depends on the tolerance threshold as well as the fraction of unlike neighbors. Two models are proposed: in model A the jump probability is determined by the sign of u only, which makes it equivalent to the discrete model. In model B the actual values of u are considered. Model A and model B are shown to differ drastically as far as segregation behavior and phase transitions are concerned. In model A, although segregation can be achieved, the cluster sizes are rather small. Also, a frozen state is obtained in which steady states comprise many unsatisfied agents. In model B, segregated states with much larger cluster sizes are obtained. The correlation function is calculated to show quantitatively that larger clusters occur in model B. Moreover for model B, no frozen states exist even for very low dilution and small tolerance parameter. This is in contrast to the unconstrained discrete model considered earlier where agents can move even when utility remains the same. In addition, we also consider a few other dynamical aspects which have not been studied in segregation models earlier.
Energy Technology Data Exchange (ETDEWEB)
Gepraegs, R.; Schmitz, G.; Peters, D. [Institut fuer Atmosphaerenphysik, Kuehlungsborn (Germany)
1997-12-31
A 2D version of the ECHAM T21 climate model has been developed. The new model includes an efficient spectral transport scheme with implicit diffusion. Furthermore, photodissociation and chemistry of the NCAR 2D model have been incorporated. A self consistent parametrization scheme is used for eddy heat- and momentum flux in the troposphere. It is based on the heat flux parametrization of Branscome and mixing-length formulation for quasi-geostrophic vorticity. Above 150 hPa the mixing-coefficient K{sub yy} is prescribed. Some of the model results are discussed, concerning especially the impact of aircraft NO{sub x} emission on the model chemistry. (author) 6 refs.
Massaro, R R; Faião-Flores, F; Rebecca, V W; Sandri, S; Alves-Fernandes, D K; Pennacchi, P C; Smalley, K S M; Maria-Engler, S S
2017-05-01
Despite the recent advances in the clinical management of melanoma, there remains a need for new pharmacological approaches to treat this cancer. 2-methoxyestradiol (2ME) is a metabolite of estrogen that has shown anti-tumor effects in many cancer types. In this study we show that 2ME treatment leads to growth inhibition in melanoma cells, an effect associated with entry into senescence, decreased pRb and Cyclin B1 expression, increased p21/Cip1 expression and G2/M cell cycle arrest. 2ME treatment also inhibits melanoma cell growth in colony formation assay, including cell lines with acquired resistance to BRAF and BRAF+MEK inhibitors. We further show that 2ME is effective against melanoma with different BRAF and NRAS mutational status. Moreover, 2ME induced the retraction of cytoplasmic projections in a 3D spheroid model and significantly decreased cell proliferation in a 3D skin reconstruct model. Together our studies bring new insights into the mechanism of action of 2ME allowing melanoma targeted therapy to be further refined. Continued progress in this area is expected to lead to improved anti-cancer treatments and the development of new and more effective clinical analogues. Copyright © 2017 Elsevier Ltd. All rights reserved.
First-order phase transition in a 2D random-field Ising model with conflicting dynamics
Crokidakis, Nuno
2009-02-01
The effects of locally random magnetic fields are considered in a nonequilibrium Ising model defined on a square lattice with nearest-neighbor interactions. In order to generate the random magnetic fields, we have considered random variables {h} that change randomly with time according to a double-Gaussian probability distribution, which consists of two single-Gaussian distributions, centered at +ho and -ho, with the same width σ. This distribution is very general and can recover in appropriate limits the bimodal distribution (\\sigma \\to 0 ) and the single-Gaussian one (ho = 0). We performed Monte Carlo simulations in lattices with linear sizes in the range L = 32-512. The system exhibits ferromagnetic and paramagnetic steady states. Our results suggest the occurrence of first-order phase transitions between the above-mentioned phases at low temperatures and large random-field intensities ho for some small values of the width σ. By means of finite size scaling, we estimate the critical exponents in the low-field region, where we have continuous phase transitions. In addition, we show a sketch of the phase diagram of the model for some values of σ.
Mani, Prashant; Tyagi, Chandra Shekhar; Srivastav, Nishant
2016-03-01
In this paper the analytical solution of the 2D Poisson's equation for single gate Fully Depleted SOI (FDSOI) MOSFET's is derived by using a Green's function solution technique. The surface potential is calculated and the threshold voltage of the device is minimized for the low power consumption. Due to minimization of threshold voltage the short channel effect of device is suppressed and after observation we obtain the device is kink free. The structure and characteristics of SingleGate FDSOI MOSFET were matched by using MathCAD and silvaco respectively.
Chung, Haejun; Sun, Xingshu; Mohite, Aditya D; Singh, Rahul; Kumar, Lokendra; Alam, Muhammad A; Bermel, Peter
2017-04-17
A key challenge in photovoltaics today is to develop cell technologies with both higher efficiencies and lower fabrication costs than incumbent crystalline silicon (c-Si) single-junction cells. While tandem cells have higher efficiencies than c-Si alone, it is generally challenging to find a low-cost, high-performance material to pair with c-Si. However, the recent emergence of 22% efficient perovskite photovoltaics has created a tremendous opportunity for high-performance, low-cost perovskite / crystalline silicon tandem photovoltaic cells. Nonetheless, two key challenges remain. First, integrating perovskites into tandem structures has not yet been demonstrated to yield performance exceeding commercially available crystalline silicon modules. Second, the stability of perovskites is inconsistent with the needs of most end-users, who install photovoltaic modules to produce power for 25 years or more. Making these cells viable thus requires innovation in materials processing, device design, fabrication, and yield. We will address these two gaps in the photovoltaic literature by investigating new types of 2D perovskite materials with n-butylammonium spacer layers, and integrating these materials into bifacial tandem solar cells providing at least 30% normalized power production. We find that an optimized 2D perovskite ((BA)2(MA)3(Sn0.6Pb0.4)4I13)/silicon bifacial tandem cell, given a globally average albedo of 30%, yields a normalized power production of 30.31%, which should be stable for extended time periods without further change in materials or encapsulation.
Francés, Alain Pascal; Berhe, Ermias; Lubczynski, Maciek
2010-05-01
Numerical flow models are nowadays a powerful and widely used tool for groundwater management. Their reliability requires both an accurate physical representation of an aquifer system and appropriate boundary conditions. While the hydraulic parameters like hydraulic conductivity (K) and storativity (S) are spatially dependent and time invariant, groundwater fluxes such as recharge (R), evapotranspiration from groundwater (ETg) and groundwater inflow/outflow (Qgw) can vary in both space and time. Multiplicity of combinations between parameters and fluxes leads to a non-uniqueness of model solutions which limits their reliability and forecasting capability. We propose to constrain groundwater models at the catchment scale by the spatio-temporal assessment of fluxes in the unsaturated zone. Although the physically based models that involve the Darcy's law and the conservation of mass through the Richard's equation constitute the most appropriate tools for fluxes assessment in the unsaturated zone, they are computationally demanding and require a complex parameterization and boundary condition definition, which restricts their application to large and regional scales. We have thus chosen to develop and apply a lumped-parameter unsaturated zone model because it uses simplified representations of the physical processes and limits the number of parameters. We present in this study the development and application of a spatio-temporal recharge model (pyEARTH-2D) coupled with the numerical flow model MODFLOW at the catchment scale. pyEARTH-2D is a lumped-parameter distributed (grid-based) model that shares the same spatial discretization of the MODFLOW model for coupling purpose. pyEARTH-2D solves the water balance in the topsoil layer using linear relations between fluxes and soil moisture on a daily basis. The partitioning of rainfall is done by taking into consideration interception, evapotranspiration, percolation, soil moisture storage and surface storage and runoff
Fault diagnosis based on continuous simulation models
Feyock, Stefan
1987-01-01
The results are described of an investigation of techniques for using continuous simulation models as basis for reasoning about physical systems, with emphasis on the diagnosis of system faults. It is assumed that a continuous simulation model of the properly operating system is available. Malfunctions are diagnosed by posing the question: how can we make the model behave like that. The adjustments that must be made to the model to produce the observed behavior usually provide definitive clues to the nature of the malfunction. A novel application of Dijkstra's weakest precondition predicate transformer is used to derive the preconditions for producing the required model behavior. To minimize the size of the search space, an envisionment generator based on interval mathematics was developed. In addition to its intended application, the ability to generate qualitative state spaces automatically from quantitative simulations proved to be a fruitful avenue of investigation in its own right. Implementations of the Dijkstra transform and the envisionment generator are reproduced in the Appendix.
Design, experimentation, and modeling of a novel continuous biodrying process
Navaee-Ardeh, Shahram
biodrying reactor were the type of biomass feed and the outlet relative humidity profiles. The biomass feed is mill specific and since one mill was studied for this study, the nutrition level of the biomass feed was found adequate for the microbial activity, and hence the type of biomass is a fixed parameter. The influence of outlet relative humidity profile was investigated on the overall performance and the complexity index of the continuous biodrying reactor. The best biodrying efficiency was achieved at an outlet relative humidity profile which controls the removal of unbound water at the wet-bulb temperature in the 1st and 2nd compartments of the reactor, and the removal of bound water at the dry-bulb temperature in the 3rd and 4th compartments. Through a systematic modeling approach, a 2-D model was developed to describe the transport phenomena in the continuous biodrying reactor. The results of the 2-D model were in satisfactory agreement with the experimental data. It was found that about 30% w/w of the total water removal (drying rate) takes place in the 1st and 2nd compartments mainly under a convection dominated mechanism, whereas about 70% w/w of the total water removal takes place in the 3rd and 4th compartments where a bioheat-diffusion dominated mechanism controls the transport phenomena. The 2-D model was found to be an appropriate tool for the estimation of the total water removal rate (drying rate) in the continuous biodrying reactor when compared to the 1-D model. A dimensionless analysis was performed on the 2-D model and established the preliminary criteria for the scale-up of the continuous biodrying process. Finally, a techno-economic assessment of the continuous biodrying process revealed that there is great potential for the implementation of the biodrying process in Canadian pulp and paper mills. The techno-economic results were compared to the other competitive existing drying technologies. It was proven that the continuous biodrying process
Evaluation of a breast software model for 2D and 3D X-ray imaging studies of the breast.
Baneva, Yanka; Bliznakova, Kristina; Cockmartin, Lesley; Marinov, Stoyko; Buliev, Ivan; Mettivier, Giovanni; Bosmans, Hilde; Russo, Paolo; Marshall, Nicholas; Bliznakov, Zhivko
2017-09-01
In X-ray imaging, test objects reproducing breast anatomy characteristics are realized to optimize issues such as image processing or reconstruction, lesion detection performance, image quality and radiation induced detriment. Recently, a physical phantom with a structured background has been introduced for both 2D mammography and breast tomosynthesis. A software version of this phantom and a few related versions are now available and a comparison between these 3D software phantoms and the physical phantom will be presented. The software breast phantom simulates a semi-cylindrical container filled with spherical beads of different diameters. Four computational breast phantoms were generated with a dedicated software application and for two of these, physical phantoms are also available and they are used for the side by side comparison. Planar projections in mammography and tomosynthesis were simulated under identical incident air kerma conditions. Tomosynthesis slices were reconstructed with an in-house developed reconstruction software. In addition to a visual comparison, parameters like fractal dimension, power law exponent β and second order statistics (skewness, kurtosis) of planar projections and tomosynthesis reconstructed images were compared. Visually, an excellent agreement between simulated and real planar and tomosynthesis images is observed. The comparison shows also an overall very good agreement between parameters evaluated from simulated and experimental images. The computational breast phantoms showed a close match with their physical versions. The detailed mathematical analysis of the images confirms the agreement between real and simulated 2D mammography and tomosynthesis images. The software phantom is ready for optimization purpose and extrapolation of the phantom to other breast imaging techniques. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
Developing a Forensic Continuous Audit Model
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Grover S. Kearns
2011-06-01
Full Text Available Despite increased attention to internal controls and risk assessment, traditional audit approaches do not seem to be highly effective in uncovering the majority of frauds. Less than 20 percent of all occupational frauds are uncovered by auditors. Forensic accounting has recognized the need for automated approaches to fraud analysis yet research has not examined the benefits of forensic continuous auditing as a method to detect and deter corporate fraud. The purpose of this paper is to show how such an approach is possible. A model is presented that supports the acceptance of forensic continuous auditing by auditors and management as an effective tool to support the audit function, meet managementâ€™s regulatory objectives, and to combat fraud. An approach to developing such a system is presented.
Chu, Po-Ting
2017-04-01
Riverine ecosystems are usually under the risk of anthropogenic contamination and climate change. With an eye to improving this situation, it is imperative to formulate corresponding policies. To provide the government with better policy-making standard, understanding of the future development of the ecosystems is quite necessary. Species distribution models (SDMs) is an ideal tool to understand the relationship between environmental variables and species occurrence.There are various species distribution models (SDMs) that have been developed and used in stream ecology. However, consensus on the selection among different models has not yet been reached. The results of inappropriate model selection include increasing uncertainty and high occurrence of prediction errors. How to choose the model that best fits the scenario among many is, therefore, of paramount importance. This study collects river channel data and Sicyopterus Japonic data in Datuan stream. We uses River2D as an efficient tool for simulating the two-dimensional flow condition of a stream segment. Then we combine six SDMs with the outputs of River2D and quantify the relationship between environmental variables and species occurrence by using six SDMs, which are respectively generalized linear model (GLM), generalized additive model (GAM), random forest model (RF), support vector machine (SVM), artificial neural network model (ANN), and ensemble model (the average of other five SDMs). We randomly split the fish data to train(70%) and validate(30%), and each model repeats this step for 1000 times. Finally, through Akaike information criterion, root-mean-square error and Kullback-Leibler divergence, we can know which model has better performance. The results demonstrated that the accuracy of River2D is greatly affected by measurement , and that Sicyopterus Japonic likes areas where the water is deep. Moreover, through the result, it is observed that ensemble model outperforms the others. Therefore, next
Schoenthaler, Martin; Schnell, Daniel; Wilhelm, Konrad; Schlager, Daniel; Adams, Fabian; Hein, Simon; Wetterauer, Ulrich; Miernik, Arkadiusz
2016-04-01
To compare task performances of novices and experts using advanced high-definition 3D versus 2D optical systems in a surgical simulator model. Fifty medical students (novices in laparoscopy) were randomly assigned to perform five standardized tasks adopted from the Fundamentals of Laparoscopic Surgery (FLS) curriculum in either a 2D or 3D laparoscopy simulator system. In addition, eight experts performed the same tasks. Task performances were evaluated using a validated scoring system of the SAGES/FLS program. Participants were asked to rate 16 items in a questionnaire. Overall task performance of novices was significantly better using stereoscopic visualization. Superiority of performances in 3D reached a level of significance for tasks peg transfer and precision cutting. No significant differences were noted in performances of experts when using either 2D or 3D. Overall performances of experts compared to novices were better in both 2D and 3D. Scorings in the questionnaires showed a tendency toward lower scores in the group of novices using 3D. Stereoscopic imaging significantly improves performance of laparoscopic phantom tasks of novices. The current study confirms earlier data based on a large number of participants and a standardized task and scoring system. Participants felt more confident and comfortable when using a 3D laparoscopic system. However, the question remains open whether these findings translate into faster and safer operations in a clinical setting.
Optoelectronics with 2D semiconductors
Mueller, Thomas
2015-03-01
Two-dimensional (2D) atomic crystals, such as graphene and layered transition-metal dichalcogenides, are currently receiving a lot of attention for applications in electronics and optoelectronics. In this talk, I will review our research activities on electrically driven light emission, photovoltaic energy conversion and photodetection in 2D semiconductors. In particular, WSe2 monolayer p-n junctions formed by electrostatic doping using a pair of split gate electrodes, type-II heterojunctions based on MoS2/WSe2 and MoS2/phosphorene van der Waals stacks, 2D multi-junction solar cells, and 3D/2D semiconductor interfaces will be presented. Upon optical illumination, conversion of light into electrical energy occurs in these devices. If an electrical current is driven, efficient electroluminescence is obtained. I will present measurements of the electrical characteristics, the optical properties, and the gate voltage dependence of the device response. In the second part of my talk, I will discuss photoconductivity studies of MoS2 field-effect transistors. We identify photovoltaic and photoconductive effects, which both show strong photoconductive gain. A model will be presented that reproduces our experimental findings, such as the dependence on optical power and gate voltage. We envision that the efficient photon conversion and light emission, combined with the advantages of 2D semiconductors, such as flexibility, high mechanical stability and low costs of production, could lead to new optoelectronic technologies.
Directory of Open Access Journals (Sweden)
Filiberto Chiabrando
2011-12-01
Full Text Available The Basilica of San Pietro is a Romanic architecture located in the municipality of Tuscania in the Lazio Region about 100 km far from Rome. In 1971 the apse dome collapsed during the earthquake and the important fresco of a Christ Pantocrator was destroyed. In 1975 the dome was reconstructed using reinforced concrete.In 2010 an integrated survey of the Church has been performed using LiDAR techniques integrated with photogrammetric and topographic methodologies in order to realize a complete 2D documentation of the Basilica of San Pietro. Thanks to the acquired data a complete multi-scale 3D model of the Church and of the surroundings was realized.The aim of this work is to present different strategies in order to realize correct documentations for Cultural Heritage knowledge, using typical 3D survey methodologies (i. e. LiDAR survey and photogrammetry.After data acquisition and processing, several 2D representations were realized in order to carry out traditional supports for the different actors involved in the conservation plans; moreover, starting from the 2D drawing a simplified 3D modeling methodology has been followed in order to define the fundamental geometry of the Basilica and the surroundings: the achieved model could be useful for a small architectural scale description of the structure and for the documentation of the surroundings. For the aforementioned small architectural scale model, the 3D modeling was realized using the information derived from the 2D drawings with an approach based on the Constructive Solid Geometry. Using this approach the real shape of the object is simplified. This methodology is employed in particular when the shape of the structures is simple or to communicate new project ideas of when, as in our case, the aim is to give an idea of the complexity of an architectural Cultural Heritage. In order to follow this objective, a small architectural scale model was realized: the area of the Civita hill was
Arboleda Zapata, M. D. J., Sr.; Arzate-Flores, J.; Guevara Betancourt, R. E., Sr.
2017-12-01
The Jalisco Block is a continental microplate produced by the extension along three large structures: the Tepic-Zacoalco rift (TZR), the Colima rift (CR) and the Chapala rift that converge in a triple junction 50 km southwest of Guadalajara, Mexico, with orientation NW-SE, N-S, and E-W respectively. The present study focuses on investigating the deep structure of the north Colima and eastern Zacoalco grabens close to the Guadalajara triple junction (GTJ). This is a first study of its type that provide insight on the grabens structures and crustal characteristics underneath. We measured along two magnetotellurics (MT) profiles that cut perpendicularly the TZR (profile ZAC), and the northern CR (profile SAY) comprising a total of 24 broad band MT soundings. The ZAC profile has 11 stations and has a NE orientation, and the SAY profile has 14 station aligned E-W. Standard processing and editing procedures were completed, and distortion analysis was applied to the data set in order to define the dimensionality and electric strike of the separated profiles. Static shift was corrected using geology information to distinguish the different types of soundings and later averaging for those soundings located over the same lithology. The Bahr dimensionality parameters showed that the medium is mainly 3D for the SAY profile and 2D for the ZAC profile; furthermore, the regional geoelectric strike azimuth calculated with Bahr methodology were -4° and -48° respectively, with good concordance with the main surface structures. The tipper analysis permitted validated these results, as the real induction vectors were nearly perpendicular to main fault structures. All soundings were rotated to the respective regional strike and a 2D simultaneous inversion of the transverse electric (TE) mode, the transvers magnetic (TM) mode and the Tipper was completed. The RMS fitting error yield 3.2% for ZAC profile and 3.7% for SAY profile. Both profiles show a shallow conductive zone at north of
Trojan, K.; Ausloos, M.; Cloots, R.
2004-01-01
A generalized so called magnetically controlled ballistic rain-like deposition (MBD) model of granular piles has been numerically investigated in 2D. The grains are taken to be elongated disks whence characterized by a two-state scalar degree of freedom, called ''nip'', their interaction being described through a Hamiltonian. Results are discussed in order to search for the effect of nip flip (or grain rotation from vertical to horizontal and conversely) probability in building a granular pil...
CALAMAZ , Madalina; COUPARD , Dominique; GIROT , Franck
2008-01-01
International audience; A new material constitutive law is implemented in a 2D finite element model to analyse the chip formation and shear localisation when machining titanium alloys. The numerical simulations use a commercial finite element software (FORGE 2005) able to solve complex thermo-mechanical problems. One of the main machining characteristics of titanium alloys is to produce segmented chips for a wide range of cutting speeds and feeds. The present study assumes that the chip segme...
Ilhan, I.; Coakley, B. J.
2013-12-01
The Chukchi Edges project was designed to establish the relationship between the Chukchi Shelf and Borderland and indirectly test theories of opening for the Canada Basin. During this cruise, ~5300 km of 2D multi-channel reflection seismic profiles and other geophysical data (swath bathymetry, gravity, magnetics, sonobuoy refraction seismic) were collected from the RV Marcus G. Langseth across the transition between the Chukchi Shelf and Chukchi Borderland, where the water depths vary from 30 m to over 3 km. Multiples occur when seismic energy is trapped in a layer and reflected from an acoustic interface more than once. Various kinds of multiples occur during seismic data acquisition. These depend on the ray-path the seismic energy follows through the layers. One of the most common multiples is the surface related multiple, which occurs due to strong acoustic impedance contrast between the air and water. The reflected seismic energy from the water surface is trapped within the water column, thus reflects from the seafloor multiple times. Multiples overprint the primary reflections and complicate data interpretation. Both surface related multiple elimination (SRME) and forward parabolic radon transform multiple modeling methods were necessary to attenuate the multiples. SRME is applied to shot gathers starting with the near offset interpolation, multiple estimation using water depths, and subtracting the model multiple from the shot gathers. This method attenuated surface related multiple energy, however, peg-leg multiples remained in the data. The parabolic radon transform method minimized the effect of these multiples. This method is applied to normal moveout (NMO) corrected common mid-point gathers (CMP). The CMP gathers are fitted or modeled with curves estimated from the reference offset, moveout range, moveout increment parameters. Then, the modeled multiples are subtracted from the data. Preliminary outputs of these two methods show that the surface related
Brune, S.; Ulvrova, M.; Williams, S.
2017-12-01
The surface of the Earth is divided into a jigsaw of tectonic plates, some carrrying continents that disperse and aggregate through time, forming transient supercontinents like Pangea and Rodinia. Here, we study continental rifting using large-scale numerical simulations with self-consistent evolution of plate boundaries, where continental break-up emerges spontaneously due to slab pull, basal drag and trench suction forces.We use the StagYY convection code employing a visco-plastic rheology in a spherical annulus geometry. We consider an incompressible mantle under the Boussinesq approximation that is basally and internally heated.We show that continental separation follows a characteristic evolution with three distinctive phases: (1) A pre-rift phase that typically lasts for several hundreds of millions of years with tectonic quiescence in the suture and extensional stresses that are slowly building up. (2) A rift phase that further divides into a slow rift period of several tens of millions of years where stresses continuously increase followed by a rift acceleration period featuring an abrupt stress drop within several millions of years. The speed-up takes place before lithospheric break-up and therefore affects the structural architecture of the rifted margins. (3) The drifting phase with initially high divergence rates persists over tens of millions of years until the system adjust to new conditions and the spreading typically slows down.By illustrating the geodynamic connection between subduction dynamics and rift evolution, our results allow new interpretations of plate tectonic reconstructions. Rift acceleration within the second phase of rifting is compensated by enhanced convergence rates at subduction zones. This model outcome predicts enhanced subduction velocities, e.g. between North America and the Farallon plate during Central Atlantic rifting 200 My ago, or closure of potential back-arc basins such as in the proto-Andean ranges of South America
Cai, Jiji; Jung, Cheolkon
2017-09-01
We propose image-guided depth propagation for two-dimensional (2-D)-to-three-dimensional (3-D) video conversion using superpixel matching and the adaptive autoregressive (AR) model. We adopt key frame-based depth propagation that propagates the depth map in the key frame to nonkey frames. Moreover, we use the adaptive AR model for depth refinement to penalize depth-color inconsistency. First, we perform superpixel matching to estimate motion vectors at the superpixel level instead of block matching based on the fixed block size. Then, we conduct depth compensation based on motion vectors to generate the depth map in the nonkey frame. However, the size of two superpixels is not exactly the same due to the segment-based matching, which causes matching errors in the compensated depth map. Thus, we introduce an adaptive image-guided AR model to minimize matching errors and produce the final depth map by minimizing AR prediction errors. Finally, we employ depth-image-based rendering to generate stereoscopic views from 2-D videos and their depth maps. Experimental results demonstrate that the proposed method successfully performs depth propagation and produces high-quality depth maps for 2-D-to-3-D video conversion.
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Li Jun
2014-12-01
Full Text Available This paper reports an experimental investigation on the macroscopic mechanical behaviors and damage mechanisms of the plain-woven (2D C/SiC composite under in-plane on- and off-axis loading conditions. Specimens with 15°, 30°, and 45° off-axis angles were prepared and tested under monotonic and incremental cyclic tension and compression loads. The obtained results were compared with those of uniaxial tension, compression, and shear specimens. The relationships between the damage modes and the stress state were analyzed based on scanning electronic microscopy (SEM observations and acoustic emission (AE data. The test results reveal the remarkable axial anisotropy and unilateral behavior of the material. The off-axis tension test results show that the material is fiber-dominant and the evolution rate of damage and inelastic strain is accelerated under the corresponding combined biaxial tension and shear loads. Due to the damage impediment effect of compression stress, compression specimens show higher mechanical properties and lower damage evolution rates than tension specimens with the same off-axis angle. Under cyclic tension–compression loadings, both on-axis and off-axis specimens exhibit progressive damage deactivation behaviors in the compression range, but with different deactivation rates.
Branch, Darren W; Wojciechowski, Kenneth E; Olsson, Roy H
2014-05-01
In this work, an approach has been developed to predict the location of large spurious modes in the resonant response of aluminum nitride (AlN) microelectromechanical systems (MEMS) resonators over a wide range of desired operating frequencies. This addresses significant challenges in the design of more complex AlN devices, namely the prediction and elimination of spurious modes in the resonance response. Using the finite element method (FEM), the dispersion curves at wavelengths ranging from 8 to 20 μm were computed. It was determined that the velocities of symmetric Lamb (S0) and high-order antisymmetric (A) modes overlap at specific wavelengths. A 2-D FEM analysis showed that both the S0 and higher order A modes are mutually excited at a common operating wavelength. From this analysis, the coupling-of-modes (COM) parameters were extracted and used to compute the P-matrix and S-parameters using a 6-port transmission matrix. The P-matrix simulation was able to predict the electrical response of the S0 and nearby spurious modes. This work identified specific wavelength regions where COM has limited accuracy because of mode conversion. In these regions, the reflection (κ(p)) and transduction (ζ(p)) parameters change rapidly.
Bateman, A.; Medina, V.; Hürlimann, M.
2009-04-01
Debris flows are present in every country where a combination of high mountains and flash floods exists. In the northern part of the Iberian Peninsula, at the Pyrenees, sporadic debris events occur. We selected two different events. The first one was triggered at La Guingueta by the big exceptional flood event that produced many debris flows in 1982 which were spread all over the Catalonian Pyrenees. The second, more local event occurred in 2000 at the mountain Montserrat at the Pre-litoral mountain chain. We present here some results of the FLATModel, entirely developed at the Research Group in Sediment Transport of the Hydraulic, Marine and Environmental Engineering Department (GITS-UPC). The 2D FLATModel is a Finite Volume method that uses the Godunov scheme. Some numerical arranges have been made to analyze the entrainment process during the events, the Stop & Go phenomena and the final deposit of the material. The material rheology implemented is the Voellmy approach, because it acts very well evaluating the frictional and turbulent behavior. The FLATModel uses a GIS environment that facilitates the data analysis as the comparison between field and numerical data. The two events present two different characteristics, one is practically a one dimensional problem of 1400 m in length and the other has a more two dimensional behavior that forms a big fan.
An end-to-end coupled model ROMS-N 2 P 2 Z 2 D 2 -OSMOSE of ...
African Journals Online (AJOL)
African Journal of Marine Science ... It is linked to the biogeochemical model through the predation process; plankton groups are food for fish and fish apply a predation mortality on plankton. Here we ... Keywords: individual-based model, model validation, pattern-oriented modelling, trophic interactions, two-way coupling
Filipovic, Vilim; Coquet, Yves; Gerke, Horst H.
2017-04-01
In arable soil landscapes, specific spatial heterogeneities related to tillage and trafficking can influence the movement of water and chemicals. The structure in the topsoil is characterized by spatial patterns with locally compacted zones. The contrasting hydraulic properties of more-and-less compacted soil zones can result in heterogeneous flow fields and preferential flow. Two- or three-dimensional models used to account for soil spatial variability are relatively too complex when trying to include local heterogeneities in the description of field scale flow and transport problems. The idea was to reduce the model complexity linked to the explicit description of heterogeneities in 2D or 3D without deteriorating the validity of simulation results. When reducing the spatial dimensionality, the geometry in a 2D, cross-sectional explicit plot description is removed on the expense of an increased complexity of the 1D model with two flow domains and mass exchange between them. Our objective was to design a simplified 1D model approach that effectively accounts for plot-scale soil structural variability. In this simplified 1D model, effective soil hydraulic parameters can be assigned to each of the two domains separately. Different theoretical scenarios simulating different shape, size and arrangement of compacted clods in the tilled layer were set to estimate their effect on solute behaviour. The mass exchange parameters could be determined from structure quantification and by comparing simplified 1D with reference 2D results accounting for defined soil structural (i.e., here the compacted regions) geometries. The mass exchange is strongly related to the geometry of the compacted zones including their distribution and size within the non-compacted soil. Additionally, the simplified model approach was tested by comparing it with measured results from a field tracer experiment.
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Coppola C
2016-11-01
Full Text Available Carmela Coppola,1 Gennaro Riccio,1 Antonio Barbieri,2 Maria Gaia Monti,3 Giovanna Piscopo,1 Domenica Rea,2 Claudio Arra,2 Carlo Maurea,1 Claudia De Lorenzo,4,5 Nicola Maurea1 1Division of Cardiology, Istituto Nazionale per lo Studio e la Cura dei Tumori “Fondazione G. Pascale”, IRCCS, Naples, Italy; 2Animal Facility Unit, Department of Experimental Oncology, Istituto Nazionale per lo Studio e la Cura dei Tumori “Fondazione G. Pascale”, IRCCS, Naples, Italy; 3Department of Translational Medical Sciences, University Federico II, Naples, Italy; 4Department of Molecular Medicine and Medical Biotechnology, University Federico II, Naples, Italy; 5CEINGE Biotecnologie Avanzate, Naples, Italy Objective: Considering that global left ventricular systolic radial strain is a sensitive technique for the early detection of left ventricular dysfunction due to antineoplastics and the analysis of segmental myocardial contractility, we evaluated this technique for early detection of trastuzumab-related cardiotoxicity by comparing it with cardiac structural damage.Methods: Groups of six mice were injected with trastuzumab or doxorubicin, used either as single agents or in combination. Cardiac function was evaluated by transthoracic echocardiography measurements before and after treatment for 2 or 7 days, by using a Vevo 2100 high-resolution imaging system. After echocardiography, mice were euthanized, and hearts were processed for histological evaluations, such as cardiac fibrosis, apoptosis, capillary density, and inflammatory response.Results: Trastuzumab-related cardiotoxicity was detected early by 2D strain imaging. Radial strain was reduced after 2 days in mice treated with trastuzumab alone (21.2%±8.0% vs 40.5%±4.8% sham; P<0.01. Similarly, trastuzumab was found to induce apoptosis, capillary density reduction, and inflammatory response in cardiac tissue after 2 days of treatment, in a fashion similar to doxorubicin. On the contrary, fractional
FTOM-2D: a two-dimensional approach to model the detailed thermal behavior of nonplanar surfaces
Bartos, B.; Stein, K.
2015-10-01
The Fraunhofer thermal object model (FTOM) predicts the temperature of an object as a function of the environmental conditions. The model has an outer layer exchanging radiation and heat with the environment and a stack of layers beyond modifying the thermal behavior. The innermost layer is at a constant or variable temperature called core temperature. The properties of the model (6 parameters) are fitted to minimize the difference between the prediction and a time series of measured temperatures. The model can be used for very different objects like backgrounds (e.g. meadow, forest, stone, or sand) or objects like vehicles. The two dimensional enhancement was developed to model more complex objects with non-planar surfaces and heat conduction between adjacent regions. In this model we call the small thermal homogenous interacting regions thermal pixels. For each thermal pixel the orientation and the identities of the adjacent pixels are stored in an array. In this version 7 parameters have to be fitted. The model is limited to a convex geometry to reduce the complexity of the heat exchange and allow for a higher number of thermal pixels. For the test of the model time series of thermal images of a test object (CUBI) were analyzed. The square sides of the cubes were modeled as 25 thermal pixels (5 × 5). In the time series of thermal images small areas in the size of the thermal pixels were analyzed to generate data files that can easily be read by the model. The program was developed with MATLAB and the final version in C++ using the OpenMP multiprocessor library. The differential equation for the heat transfer is the time consuming part in the computation and was programmed in C. The comparison show a good agreement of the fitted and not fitted thermal pixels with the measured temperatures. This indicates the ability of the model to predict the temperatures of the whole object.
Hallnan, R.; Busby, D.; Saito, L.; Daniels, M.; Danner, E.; Tyler, S.
2016-12-01
Stress on California's salmon fisheries as a result of recent drought highlights a need for effective temperature management in the Sacramento River. Cool temperatures are required for Chinook salmon spawning and rearing. At Shasta Dam in northern California, managers use selective reservoir withdrawals to meet downstream temperature thresholds set for Chinook salmon populations. Shasta Dam is equipped with a temperature control device (TCD) that allows for water withdrawals at different reservoir depths. A two-dimensional CE-QUAL-W2 (W2) model of Shasta Reservoir has been used to understand the impacts of TCD operations on reservoir and discharge dynamics at Shasta. W2 models the entire reservoir based on hydrologic and meteorological inputs, and therefore can be used to simulate various hydroclimatic conditions, reservoir operations, and resulting reservoir conditions. A limitation of the W2 model is that it only captures reservoir conditions in two dimensions (length and depth), which may not represent local hydrodynamic effects of TCD operations that could affect simulation of discharge temperatures. Thus, a three-dimensional (3D) model of the TCD and the immediately adjacent upstream reservoir has been constructed using computational fluid dynamics (CFD) in ANSYS Fluent. This 3D model provides additional insight into the mixing effects of different TCD operations, and resulting reservoir outflow temperatures. The drought conditions of 2015 provide a valuable dataset for assessing the efficacy of modeling the temperature profile of Shasta Reservoir under very low inflow volumes, so the W2 and CFD models are compared for model performance in late 2015. To assist with this assessment, data from a distributed temperature sensing (DTS) deployment at Shasta Lake since August 2015 are used. This presentation describes model results from both W2 as well as the CFD model runs during late 2015, and discuss their efficacy for modeling drought conditions.
Xue, Caifu; Zhang, Xunjie; Cai, Weimin
2017-12-21
The potential of inhibitory metabolites of perpetrator drugs to contribute to drug-drug interactions (DDIs) is uncommon and underestimated. However, the occurrence of unexpected DDI suggests the potential contribution of metabolites to the observed DDI. The aim of this study was to develop a physiologically-based pharmacokinetic (PBPK) model for bupropion and its three primary metabolites-hydroxybupropion, threohydrobupropion and erythrohydrobupropion-based on a mixed "bottom-up" and "top-down" approach and to contribute to the understanding of the involvement and impact of inhibitory metabolites for DDIs observed in the clinic. PK profiles from clinical researches of different dosages were used to verify the bupropion model. Reasonable PK profiles of bupropion and its metabolites were captured in the PBPK model. Confidence in the DDI prediction involving bupropion and co-administered CYP2D6 substrates could be maximized. The predicted maximum concentration (C max ) area under the concentration-time curve (AUC) values and C max and AUC ratios were consistent with clinically observed data. The addition of the inhibitory metabolites into the PBPK model resulted in a more accurate prediction of DDIs (AUC and C max ratio) than that which only considered parent drug (bupropion) P450 inhibition. The simulation suggests that bupropion and its metabolites contribute to the DDI between bupropion and CYP2D6 substrates. The inhibitory potency from strong to weak is hydroxybupropion, threohydrobupropion, erythrohydrobupropion, and bupropion, respectively. The present bupropion PBPK model can be useful for predicting inhibition from bupropion in other clinical studies. This study highlights the need for caution and dosage adjustment when combining bupropion with medications metabolized by CYP2D6. It also demonstrates the feasibility of applying the PBPK approach to predict the DDI potential of drugs undergoing complex metabolism, especially in the DDI involving inhibitory
Directory of Open Access Journals (Sweden)
Pleite J.
2013-01-01
Full Text Available In this paper we propose and validate by experiment a practical method to compute by simulations the inductance of a ferrite inductor as a function of the current intensity level from the linear to the saturation regions. Our method combines the use of 2D Finite Element Analysis with experimental measurements taken in a laboratory environment. We also present and analyze results of the convergence and computational cost of the 2D and 3D simulations showing the reduction of computational cost when we chose the 2D simulation.
Zelt, Colin A.; Haines, Seth; Powers, Michael H.; Sheehan, Jacob; Rohdewald, Siegfried; Link, Curtis; Hayashi, Koichi; Zhao, Don; Zhou, Hua-wei; Burton, Bethany L.; Petersen, Uni K.; Bonal, Nedra D.; Doll, William E.
2013-01-01
Seismic refraction methods are used in environmental and engineering studies to image the shallow subsurface. We present a blind test of inversion and tomographic refraction analysis methods using a synthetic first-arrival-time dataset that was made available to the community in 2010. The data are realistic in terms of the near-surface velocity model, shot-receiver geometry and the data's frequency and added noise. Fourteen estimated models were determined by ten participants using eight different inversion algorithms, with the true model unknown to the participants until it was revealed at a session at the 2011 SAGEEP meeting. The estimated models are generally consistent in terms of their large-scale features, demonstrating the robustness of refraction data inversion in general, and the eight inversion algorithms in particular. When compared to the true model, all of the estimated models contain a smooth expression of its two main features: a large offset in the bedrock and the top of a steeply dipping low-velocity fault zone. The estimated models do not contain a subtle low-velocity zone and other fine-scale features, in accord with conventional wisdom. Together, the results support confidence in the reliability and robustness of modern refraction inversion and tomographic methods.
Schubert, Jochen; Monsen, Wade; Sanders, Brett
2015-11-01
Metric resolution digital terrain models (DTMs) of rivers now make it possible for multi-dimensional fluid mechanics models to be applied to characterize flow at fine scales that are relevant to studies of river morphology and ecological habitat, or microscales. These developments are important for managing rivers because of the potential to better understand system dynamics, anthropogenic impacts, and the consequences of proposed interventions. However, the data volumes and computational demands of microscale river modeling have largely constrained applications to small multiples of the channel width, or the mesoscale. This report presents computational methods to extend a microscale river model beyond the mesoscale to the macroscale, defined as large multiples of the channel width. A method of automated unstructured grid generation is presented that automatically clusters fine resolution cells in areas of curvature (e.g., channel banks), and places relatively coarse cells in areas lacking topographic variability. This overcomes the need to manually generate breaklines to constrain the grid, which is painstaking at the mesoscale and virtually impossible at the macroscale. The method is applied to a braided river with an extremely complex channel network configuration and shown to yield an efficient fine resolution model. The sensitivity of model output to grid design and resistance parameters is also examined as it relates to analysis of hydrology, hydraulic geometry and river habitats and the findings reiterate the importance of model calibration and validation.
Directory of Open Access Journals (Sweden)
Jochen eSchubert
2015-11-01
Full Text Available Metric resolution digital terrain models (DTMs of rivers now make it possible for multi-dimensional fluid mechanics models to be applied to characterize flow at fine scales that are relevant to studies of river morphology and ecological habitat, or microscales. These developments are important for managing rivers because of the potential to better understand system dynamics, anthropogenic impacts, and the consequences of proposed interventions. However, the data volumes and computational demands of microscale river modeling have largely constrained applications to small multiples of the channel width, or the mesoscale. This report presents computational methods to extend a microscale river model beyond the mesoscale to the macroscale, defined as large multiples of the channel width. A method of automated unstructured grid generation is presented that automatically clusters fine resolution cells in areas of curvature (e.g., channel banks, and places relatively coarse cells in areas lacking topographic variability. This overcomes the need to manually generate breaklines to constrain the grid, which is painstaking at the mesoscale and virtually impossible at the macroscale. The method is applied to a braided river with an extremely complex channel network configuration and shown to yield an efficient fine resolution model. The sensitivity of model output to grid design and resistance parameters is also examined as it relates to analysis of hydrology, hydraulic geometry and river habitats and the findings reiterate the importance of model calibration and validation.
2D collisional-radiative model for non-uniform argon plasmas: with or without ‘escape factor’
International Nuclear Information System (INIS)
Zhu, Xi-Ming; Tsankov, Tsanko Vaskov; Luggenhölscher, Dirk; Czarnetzki, Uwe
2015-01-01
Collisional-radiative models for excited rare-gas atoms in low-temperature plasmas are a widely investigated topic. When these plasmas are optically thick, an ‘escape factor’ is introduced into the models to account for the reabsorption of photons (so-called radiation trapping process). This factor is usually obtained assuming a uniform density profile of the excited species; however, such an assumption is often not satisfied in a bounded plasma. This article reports for the first time a self-consistent collisional-radiative model without using an ad hoc ‘escape factor’ for excited Ar atoms in the 2p states (in Paschen’s notation). Rather, the rate balance equations—i.e. the radiation transfer equations—of the 2p states are numerically solved to yield the actual density profiles. The predictions of this self-consistent model and a model based on the escape factor concept are compared with spatially-resolved emission measurements in a low-pressure inductive Ar plasma. The self-consistent model agrees well with the experiment but the ‘escape factor’ model shows considerable deviations. By the comparative analysis the limitations and shortcomings of the escape factor concept as adopted in a significant number of works are revealed. (paper)
Duxbury, N. S.; Romanovsky, V. E.; Romanovskii, N. N.; Garagulya, L. S.; Brouchkov, A. V.; Komarov, I. A.; Roman, L. T.; Tipenko, G. S.; Buldovich, S. N.; Maximova, L. N.
2012-12-01
We have developed coupled permafrost - carbon physical and numerical models, where carbon is in the form of methane clathrate hydrate ( CH4*6H2O ) in a porous subsurface environment. The driving force for the subsurface temperature field dynamics is climate variations on the Earth's surface. This is an upper boundary condition for the nonlinear evolutionary system of partial differential equations (PDEs) describing subsurface heat transfer (parabolic PDEs) in a generalized Stefan formulation. The developed numerical model is a valuable computational tool to quantitatively study nonlinear dynamical thermal processes with phase transitions in terrestrial and Martian subsurfaces. Our model is multifrontal and therefore allows one to perform computations for a problem with any number of emerging/vanishing phase transition interfaces (both in methane gas hydrate deposits and in permafrost), since the model treats these fronts implicitly in an enthalpy formulation and in corresponding finite-difference scheme. This model takes into account the pressure (and therefore the depth) dependence of the phase transition temperature for methane clathrate hydrate. We have performed model computations using the thermophysical characteristics (heat capacity, density/porosity, thermal conductivity) for the Siberian subsurface. It can be used as a terrestrial analog for the Martian subsurface (e.g., Duxbury et al., 2001). Also, thermophysical coefficients from laboratory experiments for methane clathrate hydrate were used in our model. In addition, our model takes into account the dependence of subsurface thermophysical characteristics on temperature and spatial coordinates. The results of our computations and their interpretation will be presented. References. N. S. Duxbury, I. A. Zotikov, K. H. Nealson, V. E. Romanovsky, F. D. Carsey (2001). A numerical model for an alternative origin of Lake Vostok and its exobiological implications for Mars, Journal of Geophysical Research
Directory of Open Access Journals (Sweden)
Jakub Langhammer
2017-11-01
Full Text Available This paper explores the potential of the joint application of unmanned aerial vehicle (UAV-based photogrammetry and an automated sensor network for building a hydrodynamic flood model of a montane stream. UAV-based imagery was used for three-dimensional (3D photogrammetric reconstruction of the stream channel, achieving a resolution of 1.5 cm/pixel. Automated ultrasonic water level gauges, operating with a 10 min interval, were used as a source of hydrological data for the model calibration, and the MIKE 21 hydrodynamic model was used for building the flood model. Three different horizontal schematizations of the channel—an orthogonal grid, curvilinear grid, and flexible mesh—were used to evaluate the effect of spatial discretization on the results. The research was performed on Javori Brook, a montane stream in the Sumava (Bohemian Forest Mountains, Czech Republic, Central Europe, featuring a fast runoff response to precipitation events and that is located in a core zone of frequent flooding. The studied catchments have been, since 2007, equipped with automated water level gauges and, since 2013, under repeated UAV monitoring. The study revealed the high potential of these data sources for applications in hydrodynamic modeling. In addition to the ultra-high levels of spatial and temporal resolution, the major contribution is in the method’s high operability, enabling the building of highly detailed flood models even in remote areas lacking conventional monitoring. The testing of the data sources and model setup indicated the limitations of the UAV reconstruction of the stream bathymetry, which was completed by the geodetic-grade global navigation satellite system (GNSS measurements. The testing of the different model domain schematizations did not indicate the substantial differences that are typical for conventional low-resolution data, proving the high reliability of the tested modeling workflow.
An A_r threesome: Matrix models, 2d CFTs and 4d N=2 gauge theories
Schiappa, Ricardo; Wyllard, Niclas
2009-01-01
We explore the connections between three classes of theories: A_r quiver matrix models, d=2 conformal A_r Toda field theories and d=4 N=2 supersymmetric conformal A_r quiver gauge theories. In particular, we analyse the quiver matrix models recently introduced by Dijkgraaf and Vafa and make detailed comparisons with the corresponding quantities in the Toda field theories and the N=2 quiver gauge theories. We also make a speculative proposal for how the matrix models should be modified in orde...
An Ar threesome: Matrix models, 2d conformal field theories, and 4d N =2 gauge theories
Schiappa, Ricardo; Wyllard, Niclas
2010-08-01
We explore the connections between three classes of theories: Ar quiver matrix models, d =2 conformal Ar Toda field theories, and d =4 N =2 supersymmetric conformal Ar quiver gauge theories. In particular, we analyze the quiver matrix models recently introduced by Dijkgraaf and Vafa (unpublished) and make detailed comparisons with the corresponding quantities in the Toda field theories and the N =2 quiver gauge theories. We also make a speculative proposal for how the matrix models should be modified in order for them to reproduce the instanton partition functions in quiver gauge theories in five dimensions.
An Ar threesome: Matrix models, 2d conformal field theories, and 4dN=2 gauge theories
International Nuclear Information System (INIS)
Schiappa, Ricardo; Wyllard, Niclas
2010-01-01
We explore the connections between three classes of theories: A r quiver matrix models, d=2 conformal A r Toda field theories, and d=4N=2 supersymmetric conformal A r quiver gauge theories. In particular, we analyze the quiver matrix models recently introduced by Dijkgraaf and Vafa (unpublished) and make detailed comparisons with the corresponding quantities in the Toda field theories and the N=2 quiver gauge theories. We also make a speculative proposal for how the matrix models should be modified in order for them to reproduce the instanton partition functions in quiver gauge theories in five dimensions.
Modeling plasticity by non-continuous deformation
Ben-Shmuel, Yaron; Altus, Eli
2017-10-01
Plasticity and failure theories are still subjects of intense research. Engineering constitutive models on the macroscale which are based on micro characteristics are very much in need. This study is motivated by the observation that continuum assumptions in plasticity in which neighbour material elements are inseparable at all-time are physically impossible, since local detachments, slips and neighbour switching must operate, i.e. non-continuous deformation. Material microstructure is modelled herein by a set of point elements (particles) interacting with their neighbours. Each particle can detach from and/or attach with its neighbours during deformation. Simulations on two- dimensional configurations subjected to uniaxial compression cycle are conducted. Stochastic heterogeneity is controlled by a single "disorder" parameter. It was found that (a) macro response resembles typical elasto-plastic behaviour; (b) plastic energy is proportional to the number of detachments; (c) residual plastic strain is proportional to the number of attachments, and (d) volume is preserved, which is consistent with macro plastic deformation. Rigid body displacements of local groups of elements are also observed. Higher disorder decreases the macro elastic moduli and increases plastic energy. Evolution of anisotropic effects is obtained with no additional parameters.
Energy Technology Data Exchange (ETDEWEB)
Park, Ju Yeop; In, Wang Kee; Chun, Tae Hyun; Oh, Dong Seok [Korea Atomic Energy Research Institute, Taejeon (Korea)
2000-02-01
The development of orthogonal 2-dimensional numerical code is made. The present code contains 9 kinds of turbulence models that are widely used. They include a standard k-{epsilon} model and 8 kinds of low Reynolds number ones. They also include 6 kinds of numerical schemes including 5 kinds of low order schemes and 1 kind of high order scheme such as QUICK. To verify the present numerical code, pipe flow, channel flow and expansion pipe flow are solved by this code with various options of turbulence models and numerical schemes and the calculated outputs are compared to experimental data. Furthermore, the discretization error that originates from the use of standard k-{epsilon} turbulence model with wall function is much more diminished by introducing a new grid system than a conventional one in the present code. 23 refs., 58 figs., 6 tabs. (Author)
International Nuclear Information System (INIS)
Grant, K.E.; Taylor, K.E.; Ellis, J.S.; Wuebbles, D.J.
1987-07-01
The authors have implemented a series of state of the art radiation transport submodels in previously developed one dimensional and two dimensional chemical transport models of the troposphere and stratosphere. These submodels provide the capability of calculating accurate solar and infrared heating rates. They are a firm basis for further radiation submodel development as well as for studying interactions between radiation and model dynamics under varying conditions of clear sky, clouds, and aerosols. 37 refs., 3 figs
Directory of Open Access Journals (Sweden)
J.S.L. Oliveira
2017-06-01
Full Text Available The data in this article shows the effect of isopropyl myristate (IPM on a 2D Stratum Corneum lipid model. In the first part, the analytical characterization of the synthesized deuterated isopropyl myristate is given. Then a BAM image of the pure Stratum Corneum model used is shown and a dataset of surface-pressure – area isotherms considering various ratios of deuterated and non-deuterated IPM and the Stratum Corneum model mixture is provided. Assuming that after the plateau in the isotherm the area per molecule corresponds only to the Stratum Corneum model (squeezing out of IPM, the value of the area will correspond to the percentage of these lipids in the mixture when considering the pure SC model. The comparison of the real and the calculated areas per molecule is also done.
Fleming, Eric L.; Chandra, Sushil; Jackman, Charles H.; Considine, David B.; Douglass, Anne R.
1995-01-01
We have investigated the middle atmospheric response to the 27-day and 11-yr solar UV flux variations at low to middle latitudes using a two-dimensional photochemical model. The model reproduced most features of the observed 27-day sensitivity and phase lag of the profile ozone response in the upper stratosphere and lower mesosphere, with a maximum sensitivity of +0.51% per 1% change in 205 nm flux. The model also reproduced the observed transition to a negative phase lag above 2 mb, reflecting the increasing importance with height of the solar modulated HO(x) chemistry on the ozone response above 45 km. The model revealed the general anti-correlation of ozone and solar UV at 65-75 km, and simulated strong UV responses of water vapor and HO(x) species in the mesosphere. Consistent with previous 1D model studies, the observed upper mesospheric positive ozone response averaged over +/- 40 was simulated only when the model water vapor concentrations above 75 km were significantly reduced relative to current observations. In agreement with observations, the model computed a low to middle latitude total ozone phase lag of +3 days and a sensitivity of +0.077% per 1% change in 205 nm flux for the 27-day solar variation, and a total ozone sensitivity of +0.27% for the 11-yr solar cycle. This factor of 3 sensitivity difference is indicative of the photochemical time constant for ozone in the lower stratosphere which is comparable to the 27-day solar rotation period but is much shorter than the 11-yr solar cycle.
Krueger, Ronald; Paris, Isbelle L.; OBrien, T. Kevin; Minguet, Pierre J.
2004-01-01
The influence of two-dimensional finite element modeling assumptions on the debonding prediction for skin-stiffener specimens was investigated. Geometrically nonlinear finite element analyses using two-dimensional plane-stress and plane-strain elements as well as three different generalized plane strain type approaches were performed. The computed skin and flange strains, transverse tensile stresses and energy release rates were compared to results obtained from three-dimensional simulations. The study showed that for strains and energy release rate computations the generalized plane strain assumptions yielded results closest to the full three-dimensional analysis. For computed transverse tensile stresses the plane stress assumption gave the best agreement. Based on this study it is recommended that results from plane stress and plane strain models be used as upper and lower bounds. The results from generalized plane strain models fall between the results obtained from plane stress and plane strain models. Two-dimensional models may also be used to qualitatively evaluate the stress distribution in a ply and the variation of energy release rates and mixed mode ratios with delamination length. For more accurate predictions, however, a three-dimensional analysis is required.
International Nuclear Information System (INIS)
Chen, Hsin-Chen; Yue, Yaofeng; Sun, Mingui; Jia, Wenyan; Li, Zhaoxin; Sun, Yung-Nien; Fernstrom, John D
2013-01-01
Dietary assessment is important in health maintenance and intervention in many chronic conditions, such as obesity, diabetes and cardiovascular disease. However, there is currently a lack of convenient methods for measuring the volume of food (portion size) in real-life settings. We present a computational method to estimate food volume from a single photographic image of food contained on a typical dining plate. First, we calculate the food location with respect to a 3D camera coordinate system using the plate as a scale reference. Then, the food is segmented automatically from the background in the image. Adaptive thresholding and snake modeling are implemented based on several image features, such as color contrast, regional color homogeneity and curve bending degree. Next, a 3D model representing the general shape of the food (e.g., a cylinder, a sphere, etc) is selected from a pre-constructed shape model library. The position, orientation and scale of the selected shape model are determined by registering the projected 3D model and the food contour in the image, where the properties of the reference are used as constraints. Experimental results using various realistically shaped foods with known volumes demonstrated satisfactory performance of our image-based food volume measurement method even if the 3D geometric surface of the food is not completely represented in the input image. (paper)
Pangolin v1.0, a conservative 2-D advection model towards large-scale parallel calculation
Directory of Open Access Journals (Sweden)
A. Praga
2015-02-01
Full Text Available To exploit the possibilities of parallel computers, we designed a large-scale bidimensional atmospheric advection model named Pangolin. As the basis for a future chemistry-transport model, a finite-volume approach for advection was chosen to ensure mass preservation and to ease parallelization. To overcome the pole restriction on time steps for a regular latitude–longitude grid, Pangolin uses a quasi-area-preserving reduced latitude–longitude grid. The features of the regular grid are exploited to reduce the memory footprint and enable effective parallel performances. In addition, a custom domain decomposition algorithm is presented. To assess the validity of the advection scheme, its results are compared with state-of-the-art models on algebraic test cases. Finally, parallel performances are shown in terms of strong scaling and confirm the efficient scalability up to a few hundred cores.
International Nuclear Information System (INIS)
He Yizhu; Ding Hanlin; Liu Liufa; Shin, Keesam
2006-01-01
The morphology, topology and kinetics of normal grain growth in two-dimension were studied by computer simulation using a cellular automata (Canada) model based on the lowest energy principle. The thermodynamic energy that follows Maxwell-Boltzmann statistics has been introduced into this model for the calculation of energy change. The transition that can reduce the system energy to the lowest level is chosen to occur when there is more than one possible transition direction. The simulation results show that the kinetics of normal grain growth follows the Burke equation with the growth exponent m = 2. The analysis of topology further indicates that normal grain growth can be simulated fairly well by the present CA model. The vanishing of grains with different number of sides is discussed in the simulation
Some results on the phase diagram of the 2D Hubbard model using an analytic Lanczos method
International Nuclear Information System (INIS)
Wellard, C.J.; Witte, N.S.; Hollenberg, L.C.L.
1998-01-01
Aspects of the ground state phase diagram of the two-dimensional Hubbard Model have been determined using a new non-perturbative method based on an analytic formulation of the Lanczos algorithm. The ground state energy for arbitrary repulsion U/t and density n has been calculated using a number of trial states which are expected to be qualitatively correct in certain regimes of this model - the paramagnetic Fermi sea and the Hartree-Fock Spin Density Wave state. We find large corrections to the mean-field result that shift the paramagnetic-ferromagnetic transition to higher values of U/t and closer to half-filling. (authors)
DEFF Research Database (Denmark)
Antonsson, Arni Valur; Nguyen, Frederic; Engesgaard, Peter Knudegaard
different hydrological conditions. The results of this synthetic study demonstrated some of the (potential) benefits of applying the electrical imaging data for calibration of seawater intrusion models. Furthermore, it also shows some of the limits this method has as well as the associated uncertainties....... Compared to conventional methods, which only give (few) point information, electrical images can give data over large spatial distances but that can be of great value for groundwater modeling purposes. The aim of this study is to investigate in a synthetic way, the applicability of using electrical images....... This study was conducted as a part of the European project ALERT (GOCE-CT-2004-505329)....
Monakhova, Yulia B; Fareed, Jawed; Yao, Yiming; Diehl, Bernd W K
2018-05-10
Nuclear magnetic resonance (NMR) spectroscopy is regarded as one of the most powerful and versatile analytical approaches to assure the quality of heparin preparations. In particular, it was recently demonstrated that by using 1 H NMR coupled with chemometrics heparin and low molecular weight heparin (LMWH) samples derived from three major animal species (porcine, ovine and bovine) can be differentiated [Y.B. Monakhova et al. J. Pharm. Anal. 149 (2018) 114-119]. In this study, significant improvement of existing chemometric models was achieved by switching to 2D NMR experiments (heteronuclear multiple-quantum correlation (HMQC) and diffusion-ordered spectroscopy (DOSY)). Two representative data sets (sixty-nine heparin and twenty-two LMWH) belonged to different batches and distributed by different commercial companies were investigated. A trend for animal species differentiation was observed in the principal component analysis (PCA) score plot built based on the DOSY data. A superior model was constructed using HMQC experiments, where individual heparin (LMWH) clusters as well as their blends were clearly differentiated. The predictive power of different classification methods as well as unsupervised techniques (independent components analysis, ICA) clearly proved applicability of the model for routine heparin and LMWH analysis. The switch from 1D to 2D NMR techniques provides a wealth of additional information, which is beneficial for multivariate modeling of NMR spectroscopic data for heparin preparations. Copyright © 2018 Elsevier B.V. All rights reserved.
Simulating floods : On the application of a 2D-hydraulic model for flood hazard and risk assessment
Alkema, D.
2007-01-01
Over the last decades, river floods in Europe seem to occur more frequently and are causing more and more economic and emotional damage. Understanding the processes causing flooding and the development of simulation models to evaluate countermeasures to control that damage are important issues. This
3-D and quasi-2-D discrete element modeling of grain commingling in a bucket elevator boot system
Unwanted grain commingling impedes new quality-based grain handling systems and has proven to be an expensive and time consuming issue to study experimentally. Experimentally validated models may reduce the time and expense of studying grain commingling while providing additional insight into detail...
Gaffney, E. A.
2013-10-01
© The authors 2013. Turing morphogen models have been extensively explored in the context of large-scale self-organization in multicellular biological systems. However, reconciling the detailed biology of morphogen dynamics, while accounting for time delays associated with gene expression, reveals aberrant behaviours that are not consistent with early developmental self-organization, especially the requirement for exquisite temporal control. Attempts to reconcile the interpretation of Turing\\'s ideas with an increasing understanding of the mechanisms driving zebrafish pigmentation suggests that one should reconsider Turing\\'s model in terms of pigment cells rather than morphogens (Nakamasu et al., 2009, PNAS, 106, 8429-8434; Yamaguchi et al., 2007, PNAS, 104, 4790-4793). Here the dynamics of pigment cells is subject to response delays implicit in the cell cycle and apoptosis. Hence we explore simulations of fish skin patterning, focussing on the dynamical influence of gene expression delays in morphogen-based Turing models and response delays for cell-based Turing models. We find that reconciling the mechanisms driving the behaviour of Turing systems with observations of fish skin patterning remains a fundamental challenge.
OH and O3 in the MLT: Comparing MAHRSI and ORA measurements With the SOCRATES 2D-model
Chabrillat, S.; Kockarts, G.; Brasseur, G.; Fussen, D.; Fonteyn, D.
2001-12-01
New space-based measurements of two key chemical species in the MLT, OH and O3\\ , were recently published. The OH radical was measured for the first time in the stratosphere and the mesosphere by the MAHRSI instrument. Conway et al. [2000] showed the difficulty to explain these observations with a one-dimensional model. Ozone measurements were extracted from the ORA instrument, which uses solar occultation in the UV-visible wavelength range. More than 2500 vertical profiles of O3 at sunrise and sunset were obtained, up to 110 km altitude. This is the first ozone data set to extend above the mesopause, capturing the ozone secondary maximum in its totality. We compare these measurements with the results of the SOCRATES two-dimensional interactive model. The latest version of this model includes, among other improvements, an accurate calculation of the absorption of the Lyman-α solar line by O2\\ , molecular diffusion, and a parameterization of the gravity wave drag to accurately match the observed temperature distribution in the MLT - especially the temporal and spatial structure of the mesopause. We show that the observations of mesospheric OH and O3 in the MLT are reproduced in a very satisfactory manner using this new multi-dimensional model.
International Nuclear Information System (INIS)
Didar, Tohid Fatanat; Dolatabadi, Ali; Wüthrich, Rolf
2008-01-01
Spark-assisted chemical engraving (SACE) is an unconventional micro-machining technology based on electrochemical discharge used for micro-machining nonconductive materials. SACE 2D micro-machining with constant speed was used to machine micro-channels in glass. Parameters affecting the quality and geometry of the micro-channels machined by SACE technology with constant velocity were presented and the effect of each of the parameters was assessed. The effect of chemical etching on the geometry of micro-channels under different machining conditions has been studied, and a model is proposed for characterization of the micro-channels as a function of machining voltage and applied speed
International Nuclear Information System (INIS)
Valach, M.; Zymak, J.; Svoboda, R.
1997-01-01
This paper presents the development status of the computer codes for the WWER fuel elements thermomechanical behavior modelling under high burnup conditions at the Nuclear Research Institute Rez. The accent is given on the analysis of the results from the parametric calculations, performed by the programmes PIN-W and RODQ2D, rather than on their detailed theoretical description. Several new optional correlations for the UO2 thermal conductivity with degradation effect caused by burnup were implemented into the both codes. Examples of performed calculations document differences between previous and new versions of both programmes. Some recommendations for further development of the codes are given in conclusion. (author). 6 refs, 9 figs
Banerjee, Pritha; Kumari, Tripty; Sarkar, Subir Kumar
2018-02-01
This paper presents the 2-D analytical modeling of a front high- K gate stack triple-material gate Schottky Barrier Silicon-On-Nothing MOSFET. Using the two-dimensional Poisson's equation and considering the popular parabolic potential approximation, expression for surface potential as well as the electric field has been considered. In addition, the response of the proposed device towards aggressive downscaling, that is, its extent of immunity towards the different short-channel effects, has also been considered in this work. The analytical results obtained have been validated using the simulated results obtained using ATLAS, a two-dimensional device simulator from SILVACO.
DEFF Research Database (Denmark)
Antonsson, Arni Valur; Nguyen, Frederic; Engesgaard, Peter Knudegaard
of obtainable data. These factors can seriously hinder a successful monitoring strategy and consequently limit the reliability of the calibrated model. An effective alternative to conventional measurements is the use of geophysical methods to monitor changes in the subsurface e.g. salinity distribution...... calibration is determined by different factors, where both data quantity and quality is of crucial importance. Typically the availability of conventional monitoring installations (e.g. depth specific monitoring wells for salinity measurements) and the cost of constructing new ones limit the amount....... Compared to conventional methods, which only give (few) point information, electrical images can give data over large spatial distances but that can be of great value for groundwater modeling purposes. The aim of this study is to investigate in a synthetic way, the applicability of using electrical images...
2015-01-05
in a research position that will apply her skills at granular experiment and modeling to important issues related to pharmaceutical processing...photoelastic techniques was part of an overall exhibit at the Mueseum of Science and Industry in Chicago that received a Gold medal. • Since September...organized an international Pan-American scientific program on granular materials in La Plata, Argentina in August, 2014. • The PI is co-founder and
First-order phase transition in a 2D random-field Ising model with conflicting dynamics
Crokidakis, N.
2009-01-01
The effects of locally random magnetic fields are considered in a nonequilibrium Ising model defined on a square lattice with nearest-neighbors interactions. In order to generate the random magnetic fields, we have considered random variables $\\{h\\}$ that change randomly with time according to a double-gaussian probability distribution, which consists of two single gaussian distributions, centered at $+h_{o}$ and $-h_{o}$, with the same width $\\sigma$. This distribution is very general, and c...
A Coupled 2 × 2D Babcock-Leighton Solar Dynamo Model. I. Surface Magnetic Flux Evolution
Lemerle, Alexandre; Charbonneau, Paul; Carignan-Dugas, Arnaud
2015-09-01
The need for reliable predictions of the solar activity cycle motivates the development of dynamo models incorporating a representation of surface processes sufficiently detailed to allow assimilation of magnetographic data. In this series of papers we present one such dynamo model, and document its behavior and properties. This first paper focuses on one of the model’s key components, namely surface magnetic flux evolution. Using a genetic algorithm, we obtain best-fit parameters of the transport model by least-squares minimization of the differences between the associated synthetic synoptic magnetogram and real magnetographic data for activity cycle 21. Our fitting procedure also returns Monte Carlo-like error estimates. We show that the range of acceptable surface meridional flow profiles is in good agreement with Doppler measurements, even though the latter are not used in the fitting process. Using a synthetic database of bipolar magnetic region (BMR) emergences reproducing the statistical properties of observed emergences, we also ascertain the sensitivity of global cycle properties, such as the strength of the dipole moment and timing of polarity reversal, to distinct realizations of BMR emergence, and on this basis argue that this stochasticity represents a primary source of uncertainty for predicting solar cycle characteristics.
A COUPLED 2 × 2D BABCOCK–LEIGHTON SOLAR DYNAMO MODEL. I. SURFACE MAGNETIC FLUX EVOLUTION
International Nuclear Information System (INIS)
Lemerle, Alexandre; Charbonneau, Paul; Carignan-Dugas, Arnaud
2015-01-01
The need for reliable predictions of the solar activity cycle motivates the development of dynamo models incorporating a representation of surface processes sufficiently detailed to allow assimilation of magnetographic data. In this series of papers we present one such dynamo model, and document its behavior and properties. This first paper focuses on one of the model’s key components, namely surface magnetic flux evolution. Using a genetic algorithm, we obtain best-fit parameters of the transport model by least-squares minimization of the differences between the associated synthetic synoptic magnetogram and real magnetographic data for activity cycle 21. Our fitting procedure also returns Monte Carlo-like error estimates. We show that the range of acceptable surface meridional flow profiles is in good agreement with Doppler measurements, even though the latter are not used in the fitting process. Using a synthetic database of bipolar magnetic region (BMR) emergences reproducing the statistical properties of observed emergences, we also ascertain the sensitivity of global cycle properties, such as the strength of the dipole moment and timing of polarity reversal, to distinct realizations of BMR emergence, and on this basis argue that this stochasticity represents a primary source of uncertainty for predicting solar cycle characteristics
A COUPLED 2 × 2D BABCOCK–LEIGHTON SOLAR DYNAMO MODEL. I. SURFACE MAGNETIC FLUX EVOLUTION
Energy Technology Data Exchange (ETDEWEB)
Lemerle, Alexandre; Charbonneau, Paul; Carignan-Dugas, Arnaud, E-mail: lemerle@astro.umontreal.ca, E-mail: paulchar@astro.umontreal.ca [Département de physique, Université de Montréal, 2900 boul. Édouard-Montpetit, Montréal, QC, H3T 1J4 (Canada)
2015-09-01
The need for reliable predictions of the solar activity cycle motivates the development of dynamo models incorporating a representation of surface processes sufficiently detailed to allow assimilation of magnetographic data. In this series of papers we present one such dynamo model, and document its behavior and properties. This first paper focuses on one of the model’s key components, namely surface magnetic flux evolution. Using a genetic algorithm, we obtain best-fit parameters of the transport model by least-squares minimization of the differences between the associated synthetic synoptic magnetogram and real magnetographic data for activity cycle 21. Our fitting procedure also returns Monte Carlo-like error estimates. We show that the range of acceptable surface meridional flow profiles is in good agreement with Doppler measurements, even though the latter are not used in the fitting process. Using a synthetic database of bipolar magnetic region (BMR) emergences reproducing the statistical properties of observed emergences, we also ascertain the sensitivity of global cycle properties, such as the strength of the dipole moment and timing of polarity reversal, to distinct realizations of BMR emergence, and on this basis argue that this stochasticity represents a primary source of uncertainty for predicting solar cycle characteristics.
Directory of Open Access Journals (Sweden)
Gyujin Kim
2017-08-01
Full Text Available The multiple injection strategy has been widely used in diesel engines to reduce engine noise, NOx and soot formation. Fuel injection developments such as the common-rail and piezo-actuator system provide more precise control of the injection quantity and time under higher injection pressures. As various injection strategies become accessible, it is important to understand the interaction of each fuel stream and following combustion process under the multiple injection strategy. To investigate these complex processes quantitatively, numerical analysis using CFD is a good alternative to overcome the limitation of experiments. A modified 2-D flamelet model is further developed from previous work to model multi-fuel streams with higher accuracy. The model was validated under various engine operating conditions and captures the combustion and emissions characteristics as well as several parametric variations. The model is expected to be used to suggest advanced injection strategies in engine development processes.
DEFF Research Database (Denmark)
Ferreira, C.; Gonzalez, A.; Baldacchino, D.
2016-01-01
is the application of flow control devices, such as flaps. In Task 3.2: Development of aerodynamic codes for modelling of flow devices on aerofoils and, rotors of the Avatar project, aerodynamic codes are benchmarked and validated against the experimental data of a DU95W180 airfoil in steady and unsteady flow......, for different angle of attack and flap settings, including unsteady oscillatory trailing-edge-flap motion, carried out within the framework of WP3: Models for Flow Devices and Flow Control, Task 3.1: CFD and Experimental Database. The aerodynamics codes are: AdaptFoil2D, Foil2W, FLOWer, MaPFlow, OpenFOAM, Q3UIC......, ATEFlap. The codes include unsteady Eulerian CFD simulations with grid deformation, panel models and indicial engineering models. The validation cases correspond to 18 steady flow cases, and 42 unsteady flow cases, for varying angle of attack, flap deflection and reduced frequency, with free and forced...
Aji Hapsoro, Cahyo; Purqon, Acep; Srigutomo, Wahyu
2017-07-01
2-D Time Domain Electromagnetic (TDEM) has been successfully conducted to illustrate the value of Electric field distribution under the Earth surface. Electric field compared by magnetic field is used to analyze resistivity and resistivity is one of physical properties which very important to determine the reservoir potential area of geothermal systems as one of renewable energy. In this modeling we used Time Domain Electromagnetic method because it can solve EM field interaction problem with complex geometry and to analyze transient problems. TDEM methods used to model the value of electric and magnetic fields as a function of the time combined with the function of distance and depth. The result of this modeling is Electric field intensity value which is capable to describe the structure of the Earth’s subsurface. The result of this modeling can be applied to describe the Earths subsurface resistivity values to determine the reservoir potential of geothermal systems.
Cresson, T; Chav, R; Branchaud, D; Humbert, L; Godbout, B; Aubert, B; Skalli, W; De Guise, J A
2009-01-01
3D reconstructions of the spine from a frontal and sagittal radiographs is extremely challenging. The overlying features of soft tissues and air cavities interfere with image processing. It is also difficult to obtain information that is accurate enough to reconstruct complete 3D models. To overcome these problems, the proposed method efficiently combines the partial information contained in two images from a patient with a statistical 3D spine model generated from a database of scoliotic patients. The algorithm operates through two simultaneous iterating processes. The first one generates a personalized vertebra model using a 2D/3D registration process with bone boundaries extracted from radiographs, while the other one infers the position and the shape of other vertebrae from the current estimation of the registration process using a statistical 3D model. Experimental evaluations have shown good performances of the proposed approach in terms of accuracy and robustness when compared to CT-scan.
Li, Xiaofan; Sui, C.-H.; Lau, K-M.; Adamec, D.
1999-01-01
A two-dimensional coupled ocean-cloud resolving atmosphere model is used to investigate possible roles of convective scale ocean disturbances induced by atmospheric precipitation on ocean mixed-layer heat and salt budgets. The model couples a cloud resolving model with an embedded mixed layer-ocean circulation model. Five experiment are performed under imposed large-scale atmospheric forcing in terms of vertical velocity derived from the TOGA COARE observations during a selected seven-day period. The dominant variability of mixed-layer temperature and salinity are simulated by the coupled model with imposed large-scale forcing. The mixed-layer temperatures in the coupled experiments with 1-D and 2-D ocean models show similar variations when salinity effects are not included. When salinity effects are included, however, differences in the domain-mean mixed-layer salinity and temperature between coupled experiments with 1-D and 2-D ocean models could be as large as 0.3 PSU and 0.4 C respectively. Without fresh water effects, the nocturnal heat loss over ocean surface causes deep mixed layers and weak cooling rates so that the nocturnal mixed-layer temperatures tend to be horizontally-uniform. The fresh water flux, however, causes shallow mixed layers over convective areas while the nocturnal heat loss causes deep mixed layer over convection-free areas so that the mixed-layer temperatures have large horizontal fluctuations. Furthermore, fresh water flux exhibits larger spatial fluctuations than surface heat flux because heavy rainfall occurs over convective areas embedded in broad non-convective or clear areas, whereas diurnal signals over whole model areas yield high spatial correlation of surface heat flux. As a result, mixed-layer salinities contribute more to the density differences than do mixed-layer temperatures.
Bonfanti, C.; Chiabrando, F.; Rinaudo, F.
2013-07-01
TLS (Terrestrial Laser Scanners) data today represents one of the most attractive ways to face the metric survey of an architectural object. When a restoration project is needed not many restorers are used to managing 3D models and traditional graphic results such as plans and sections are usually required. The paper defines a correct balance between the use of traditional (manual and total station) and TLS techniques in order to satisfy the usual requirements for the metric survey of an architectural object in order to obtain a complete 2D documentation of the San Giovanni Church in Saluzzo (Cn)- Italy that would be used for the restoration both of the decorative apparatus and of the structure of the church. Furthermore using the acquired 3D data some tests on commercial and open-source software for 3D modeling purpose are realised. The paper deals first of all with the followed methodology for the 2D documentation starting from 3D data. Moreover an analysis and a comparison between different software packages for the 3D modeling phase is reported.
Martinez de Pinillos Bayona, Alejandra; Woodhams, Josephine H; Pye, Hayley; Hamoudi, Rifat A; Moore, Caroline M; MacRobert, Alexander J
2017-05-01
This study shows the therapeutic outcome of Photochemical Internalisation (PCI) in prostate cancer in vitro surpasses that of Photodynamic Therapy (PDT) and could improve prostate PDT in the clinic, whilst avoiding chemotherapeutics side effects. In addition, the study assesses the potential of PCI with two different photosensitisers (TPCS 2a and TPPS 2a ) in prostate cancer cells (human PC3 and rat MatLyLu) using standard 2D monolayer culture and 3D biomimetic model. Photosensitisers were used alone for photodynamic therapy (PDT) or with the cytotoxin saporin (PCI). TPPS 2a and TPCS 2a were shown to be located in discrete cytoplasmic vesicles before light treatment and redistribute into the cytosol upon light excitation. PC3 cells exhibit a higher uptake than MatLyLu cells for both photosensitisers. In the 2D model, PCI resulted in greater cell death than PDT alone in both cell lines. In 3D model, morphological changes were also observed. Saporin-based toxicity was negligible in PC3 cells, but pronounced in MatLyLu cells (IC50 = 18 nM). In conclusion, the study showed that tumour features such as tumour cell growth rate or interaction with drugs determine therapeutic conditions for optimal photochemical treatment in metastatic prostate cancer. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.
Phase transitions in lattice 2D O(N) sigma-model with mixed action in the large N limit
Energy Technology Data Exchange (ETDEWEB)
Magnoli, N.; Ravanini, F.
1987-03-01
We study the exact N->infinity solution of the two-dimensional lattice o(N) sigma-model, described by a two parameter action that mixes Wilson (quadratic) and RP/sup N-1/proportional to O(N)/Z/sub 2/ (quartic) actions. A rich phase structure emerges, with a first order transition line crossing, in the two-dimensional parameter space the RP/sup N-1/ axis. At the end of this line the specific-heat diverges while the correlation length remains finite.
Two-loop coupling constant renormalization in lattice SU(N)xSU(N) 2D chiral models
Energy Technology Data Exchange (ETDEWEB)
Magnoli, N.; Ravanini, F.
1986-08-01
For the most general link action of lattice SU(N)xSU(N) two dimensional chiral models, the two loop coupling constant renormalization is discussed in the context of the background field method. A non-linear reparametrization of the fields, necessary to keep the invariance of the theory, introduces unpleasant extra-terms. However some of the non-universal contributions are unaffected by these extra-terms and can be easily calculated. This allows to compute the difference between the first non-universal coefficients of the Callan-Symanzik beta functions for two actions having the same scale ..lambda...
Directory of Open Access Journals (Sweden)
Francesca Galassi
Full Text Available Assessment of coronary stenosis severity is crucial in clinical practice. This study proposes a novel method to generate 3D models of stenotic coronary arteries, directly from 2D coronary images, and suitable for immediate assessment of the stenosis severity.From multiple 2D X-ray coronary arteriogram projections, 2D vessels were extracted. A 3D centreline was reconstructed as intersection of surfaces from corresponding branches. Next, 3D luminal contours were generated in a two-step process: first, a Non-Uniform Rational B-Spline (NURBS circular contour was designed and, second, its control points were adjusted to interpolate computed 3D boundary points. Finally, a 3D surface was generated as an interpolation across the control points of the contours and used in the analysis of the severity of a lesion. To evaluate the method, we compared 3D reconstructed lesions with Optical Coherence Tomography (OCT, an invasive imaging modality that enables high-resolution endoluminal visualization of lesion anatomy.Validation was performed on routine clinical data. Analysis of paired cross-sectional area discrepancies indicated that the proposed method more closely represented OCT contours than conventional approaches in luminal surface reconstruction, with overall root-mean-square errors ranging from 0.213mm2 to 1.013mm2, and maximum error of 1.837mm2. Comparison of volume reduction due to a lesion with corresponding FFR measurement suggests that the method may help in estimating the physiological significance of a lesion.The algorithm accurately reconstructed 3D models of lesioned arteries and enabled quantitative assessment of stenoses. The proposed method has the potential to allow immediate analysis of the stenoses in clinical practice, thereby providing incremental diagnostic and prognostic information to guide treatments in real time and without the need for invasive techniques.
Eckert, Dominik; Kürzinger, Petra; Bauer, Robert; Griebler, Christian; Cirpka, Olaf A.
2015-01-01
Biodegradation in contaminated aquifers has been shown to be most pronounced at the fringe of contaminant plumes, where mixing of contaminated water and ambient groundwater, containing dissolved electron acceptors, stimulates microbial activity. While physical mixing of contaminant and electron acceptor by transverse dispersion has been shown to be the major bottleneck for biodegradation in steady-state plumes, so far little is known on the effect of flow and transport dynamics (caused, e.g., by a seasonally fluctuating groundwater table) on biodegradation in these systems. Towards this end we performed experiments in quasi-two-dimensional flow-through microcosms on aerobic toluene degradation by Pseudomonas putida F1. Plume dynamics were simulated by vertical alteration of the toluene plume position and experimental results were analyzed by reactive-transport modeling. We found that, even after disappearance of the toluene plume for two weeks, the majority of microorganisms stayed attached to the sediment and regained their full biodegradation potential within two days after reappearance of the toluene plume. Our results underline that besides microbial growth, also maintenance and dormancy are important processes that affect biodegradation performance under transient environmental conditions and therefore deserve increased consideration in future reactive-transport modeling.
Testing the 231Pa/230Th paleo-circulation proxy: A data versus 2D model comparison
International Nuclear Information System (INIS)
Lippold, Jorg; Gherardi, Jeanne-Marie; Luo, Yiming
2011-01-01
Variations of the Atlantic Meridional Overturning Circulation (AMOC) are believed to have crucially influenced Earth's climate due to its key role in the inter-hemispheric redistribution of heat and carbon. To assess its past strength, the sedimentary 231 Pa/ 230 Th proxy has been developed and improved but also contested due to its sensitivity to other factors beyond ocean circulation. In order to provide a better basis for the understanding of the Atlantic 231 Pa/ 230 Th system, and therefore to shed light on the controversy, we compare new measurements of Holocene sediments from the north Brazilian margin to water column data and the output of a two-dimensional scavenging-circulation model, based on modern circulation patterns and reversible scavenging parameters. We show that sedimentary 231 Pa/ 230 Th data from one specific area of the Atlantic are in very good agreement with model results suggesting that sedimentary 231 Pa/ 230 Th is predominantly driven by the AMOC. Therefore, 231 Pa/ 230 Th represents an appropriate method to reconstruct past AMOC at least qualitatively along the western margin. (authors)
International Nuclear Information System (INIS)
Rouizi, Y; Favennec, Y; Girault, M; Petit, D
2008-01-01
The computation of fluid mechanics problems usually leans on a discretization of the Navier-Stokes equations which has to be so fine that the dimensions of the linear systems to be solved are very high. As a direct consequence, the Central Processing Unit time needed to solve complex systems my become extremely large when accuracy is demanded. When coupling numerical modeling schemes to inversion or control problems, the size of linear systems to be solved has to be drastically reduced. Within this context, the identification method consists in identifying the components of a low-order matrix system. The identification process works as an inverse problem of parameter estimation. The test case shows the ability of the proposed method to reduced with accuracy a particular fluid mechanics problem.
Two-Phase Acto-Cytosolic Fluid Flow in a Moving Keratocyte: A 2D Continuum Model.
Nikmaneshi, M R; Firoozabadi, B; Saidi, M S
2015-09-01
The F-actin network and cytosol in the lamellipodia of crawling cells flow in a centripetal pattern and spout-like form, respectively. We have numerically studied this two-phase flow in the realistic geometry of a moving keratocyte. Cytosol has been treated as a low viscosity Newtonian fluid flowing through the high viscosity porous medium of F-actin network. Other involved phenomena including myosin activity, adhesion friction, and interphase interaction are also discussed to provide an overall view of this problem. Adopting a two-phase coupled model by myosin concentration, we have found new accurate perspectives of acto-cytosolic flow and pressure fields, myosin distribution, as well as the distribution of effective forces across the lamellipodia of a keratocyte with stationary shape. The order of magnitude method is also used to determine the contribution of forces in the internal dynamics of lamellipodia.
Archer, D. E.; McGuire, P. C.; Buffett, B. A.
2010-12-01
Carbon and oxygen isotopic variations through the Paleocene-Eocene thermal maximum event suggest that biogenic methane was not the source of the perturbing carbon, but this does not guarantee that the hydrates on Earth today will not eventually respond to the unique provocation of the global warming climate event. The SpongeBOB ocean methane hydrate model is used to simulate the accumulation of sediment along a passive continental margin over geologic time scales. Fluid motions within the sediment column are driven by compaction and variations in sediment permeability, and they impact the efficiency of methane trapping within hydrate deposits. The equilibrium and transient sensitivity of the methane inventory in the sediments to the temperature of the ocean will be assessed.
Shobe, Charles M.; Tucker, Gregory E.; Barnhart, Katherine R.
2017-12-01
Models of landscape evolution by river erosion are often either transport-limited (sediment is always available but may or may not be transportable) or detachment-limited (sediment must be detached from the bed but is then always transportable). While several models incorporate elements of, or transition between, transport-limited and detachment-limited behavior, most require that either sediment or bedrock, but not both, are eroded at any given time. Modeling landscape evolution over large spatial and temporal scales requires a model that can (1) transition freely between transport-limited and detachment-limited behavior, (2) simultaneously treat sediment transport and bedrock erosion, and (3) run in 2-D over large grids and be coupled with other surface process models. We present SPACE (stream power with alluvium conservation and entrainment) 1.0, a new model for simultaneous evolution of an alluvium layer and a bedrock bed based on conservation of sediment mass both on the bed and in the water column. The model treats sediment transport and bedrock erosion simultaneously, embracing the reality that many rivers (even those commonly defined as bedrock rivers) flow over a partially alluviated bed. SPACE improves on previous models of bedrock-alluvial rivers by explicitly calculating sediment erosion and deposition rather than relying on a flux-divergence (Exner) approach. The SPACE model is a component of the Landlab modeling toolkit, a Python-language library used to create models of Earth surface processes. Landlab allows efficient coupling between the SPACE model and components simulating basin hydrology, hillslope evolution, weathering, lithospheric flexure, and other surface processes. Here, we first derive the governing equations of the SPACE model from existing sediment transport and bedrock erosion formulations and explore the behavior of local analytical solutions for sediment flux and alluvium thickness. We derive steady-state analytical solutions for
Computer Aided Continuous Time Stochastic Process Modelling
DEFF Research Database (Denmark)
Kristensen, N.R.; Madsen, Henrik; Jørgensen, Sten Bay
2001-01-01
A grey-box approach to process modelling that combines deterministic and stochastic modelling is advocated for identification of models for model-based control of batch and semi-batch processes. A computer-aided tool designed for supporting decision-making within the corresponding modelling cycle...
Energy Technology Data Exchange (ETDEWEB)
Gudyma, Iu. [Department of General Physics, Chernivtsi National University, Chernivtsi 58012 (Ukraine); Maksymov, A., E-mail: maxyartur@gmail.com [Department of General Physics, Chernivtsi National University, Chernivtsi 58012 (Ukraine); Advanced Material Research Institute (AMRI), University of New Orleans, New Orleans, LA 70148 (United States); Spinu, L. [Advanced Material Research Institute (AMRI), University of New Orleans, New Orleans, LA 70148 (United States); Department of Physics, University of New Orleans, New Orleans, LA 70148 (United States)
2015-10-15
Highlights: • We study the thermal hysteresis in spin-crossover nanoparticles with stochastic perturbation. • The dependence of system behavior on its dimensionality and size were examined. • The spin-crossover compounds where described by breathing crystal field Ising-like model. • The fluctuations may enlarge the hysteresis width which is dependent on the system size. - Abstract: The spin-crossover nanoparticles of different sizes and stochastic perturbations in external field taking into account the influence of the dimensionality of the lattice was studied. The analytical tools used for the investigation of spin-crossover system are based on an Ising-like model described using of the breathing crystal field concept. The changes of transition temperatures characterizing the systems’ bistable properties for 2D and 3D lattices, and their dependence on its size and fluctuations strength were obtained. The state diagrams with hysteretic and non-hysteretic behavior regions have also been determined.
Directory of Open Access Journals (Sweden)
Luis Carlos Ruiloba
2018-03-01
Full Text Available This paper aims to show how numerical modelling based on 2D SWE can be used to analyze the cleaning effectiveness of flushing waves in storm tanks. The case study under consideration is an existing storm tank located in Badalona, a municipality of Barcelona, Spain. Storm tank cleaning systems are critical features that must be carefully addressed. If not appropriately addressed, operation and maintenance work costs can drastically increase. There are numerous currently available technologies for cleaning storage tanks. However, no specific guide on this field has been identified. References are provided by the manufacturers through their commercial catalogues. Generally, this information is not based on experimental or numerical experiences or results have not been published in the literature of scientific papers. In this study, a public domain software (IBER was used to develop 2D hydraulic analysis of the selected tank. The results obtained show how the phenomenon of recirculation is acting in some areas of the lane. This implies a dissipation of energy, thus causing difficulties in terms of cleaning procedures. Furthermore, two new scenarios have been tested to determine how a different lane width might affect hydrodynamic behavior. A newly suggested geometry for the existing lane of the tank is proposed by using the numerical modeling software. The proposed geometry in the current pilot tank achieves higher velocities and avoids recirculation areas. The results demonstrate that numerical modelling of these types of processes is possible with the computer models available (commercial codes and can be used to optimize cleaning system design.
Energy Technology Data Exchange (ETDEWEB)
Yan, Eugene [Argonne National Lab. (ANL), Argonne, IL (United States); Pierce, Julia [Argonne National Lab. (ANL), Argonne, IL (United States); Mahat, Vinod [Argonne National Lab. (ANL), Argonne, IL (United States); Jared, Alissa [Argonne National Lab. (ANL), Argonne, IL (United States); Collis, Scott [Argonne National Lab. (ANL), Argonne, IL (United States); Verner, Duane [Argonne National Lab. (ANL), Argonne, IL (United States); Wall, Thomas [Argonne National Lab. (ANL), Argonne, IL (United States)
2016-11-01
This project is a part of the Regional Resiliency Assessment Program, led by the Department of Homeland Security, to address flooding hazards of regional significance for Portland, Maine. The pilot study was performed by Argonne National Laboratory to identify differences in spatial rainfall distributions between the radar-derived and rain-gauge rainfall datasets and to evaluate their impacts on urban flooding. The flooding impact analysis utilized a high-resolution 2-dimensional (2-D) hydrodynamic model (15 ft by 15 ft) incorporating the buildings, streets, stream channels, hydraulic structures, an existing city storm drain system, and assuming a storm surge along the coast coincident with a heavy rainfall event. Two historical storm events from April 16, 2007, and September 29, 2015, were selected for evaluation. The radar-derived rainfall data at a 200-m resolution provide spatially-varied rainfall patterns with a wide range of intensities for each event. The resultant maximum flood depth using data from a single rain gauge within the study area could be off (either under- or over-estimated) by more than 10% in the 2007 storm and more than 60% in the 2015 storm compared to the radar-derived rainfall data. The model results also suggest that the inundation area with a flow depth at or greater than 0.5 ft could reach 11% (2007 storm) and 17% (2015 storm) of the total study area, respectively. The lowland areas within the neighborhoods of North Deering, East Deering, East and West Baysides and northeastern Parkside, appear to be more vulnerable to the flood hazard in both storm events. The high-resolution 2-D hydrodynamic model with high-resolution radar-derived rainfall data provides an excellent tool for detailed urban flood analysis and vulnerability assessment. The model developed in this study could be potentially used to evaluate any proposed mitigation measures and optimize their effects in the future for Portland, ME.
Benedetti, Ivano; Nguyen, Hoang; Soler-Crespo, Rafael A.; Gao, Wei; Mao, Lily; Ghasemi, Arman; Wen, Jianguo; Nguyen, SonBinh; Espinosa, Horacio D.
2018-03-01
Novel 2D materials, e.g., graphene oxide (GO), are attractive building blocks in the design of advanced materials due to their reactive chemistry, which can enhance interfacial interactions while providing good in-plane mechanical properties. Recent studies have hypothesized that the randomly distributed two-phase microstructure of GO, which arises due to its oxidized chemistry, leads to differences in nano- vs meso-scale mechanical responses. However, this effect has not been carefully studied using molecular dynamics due to computational limitations. Herein, a continuum mechanics model, formulated based on density functional based tight binding (DFTB) constitutive results for GO nano-flakes, is establish for capturing the effect of oxidation patterns on the material mechanical properties. GO is idealized as a continuum heterogeneous two-phase material, where the mechanical response of each phase, graphitic and oxidized, is informed from DFTB simulations. A finite element implementation of the model is validated via MD simulations and then used to investigate the existence of GO representative volume elements (RVE). We find that for the studied GO, an RVE behavior arises for monolayer sizes in excess to 40 nm. Moreover, we reveal that the response of monolayers with two main different functional chemistries, epoxide-rich and hydroxyl-rich, present distinct differences in mechanical behavior. In addition, we explored the role of defect density in GO, and validate the applicability of the model to larger length scales by predicting membrane deflection behavior, in close agreement with previous experimental and theoretical observations. As such the work presents a reduced order modeling framework applicable in the study of mechanical properties and deformation mechanisms in 2D multiphase materials.
Energy Technology Data Exchange (ETDEWEB)
Kasinathan, N.; Rajakumar, A.; Vaidyanathan, G.; Chetal, S.C. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India)
1995-09-01
Post shutdown decay heat removal is an important safety requirement in any nuclear system. In order to improve the reliability of this function, Liquid metal (sodium) cooled fast breeder reactors (LMFBR) are equipped with redundant hot pool dipped immersion coolers connected to natural draught air cooled heat exchangers through intermediate sodium circuits. During decay heat removal, flow through the core, immersion cooler primary side and in the intermediate sodium circuits are also through natural convection. In order to establish the viability and validate computer codes used in making predictions, a 1:20 scale experimental model called RAMONA with water as coolant has been built and experimental simulation of decay heat removal situation has been performed at KfK Karlsruhe. Results of two such experiments have been compiled and published as benchmarks. This paper brings out the results of the numerical simulation of one of the benchmark case through a 1D/2D coupled code system, DHDYN-1D/THYC-2D and the salient features of the comparisons. Brief description of the formulations of the codes are also included.
Brown, James L.
2014-01-01
Examined is sensitivity of separation extent, wall pressure and heating to variation of primary input flow parameters, such as Mach and Reynolds numbers and shock strength, for 2D and Axisymmetric Hypersonic Shock Wave Turbulent Boundary Layer interactions obtained by Navier-Stokes methods using the SST turbulence model. Baseline parametric sensitivity response is provided in part by comparison with vetted experiments, and in part through updated correlations based on free interaction theory concepts. A recent database compilation of hypersonic 2D shock-wave/turbulent boundary layer experiments extensively used in a prior related uncertainty analysis provides the foundation for this updated correlation approach, as well as for more conventional validation. The primary CFD method for this work is DPLR, one of NASA's real-gas aerothermodynamic production RANS codes. Comparisons are also made with CFL3D, one of NASA's mature perfect-gas RANS codes. Deficiencies in predicted separation response of RANS/SST solutions to parametric variations of test conditions are summarized, along with recommendations as to future turbulence approach.
Balucani, Nadia; Bergeat, Astrid; Cartechini, Laura; Volpi, Gian Gualberto; Casavecchia, Piergiorgio; Skouteris, Dimitris; Rosi, Marzio
2009-10-22
The dynamics of the H-displacement channel in the reaction N((2)D) + CH(4) has been investigated by the crossed molecular beam (CMB) technique with mass spectrometric detection and time-of-flight (TOF) analysis at five different collision energies (from 22.2 up to 65.1 kJ/mol). The CMB results have identified two distinct isomers as primary reaction products, methanimine and methylnitrene, the yield of which significantly varies with the total available energy. From the derived center-of-mass product angular and translational energy distributions the reaction micromechanisms, the product energy partitioning and the relative branching ratios of the competing reaction channels leading to the two isomers have been obtained. The interpretation of the scattering results is assisted by new ab initio electronic structure calculations of stationary points and product energetics for the CH(4)N ground state doublet potential energy surface. Differently from previous theoretical studies, both insertion and H-abstraction pathways have been found to be barrierless at all levels of theory employed in this work. A comparison between experimental results on the two isomer branching ratio and RRKM estimates, based on the new electronic structure calculations, confirms the highly nonstatistical nature of the N((2)D) + CH(4) reaction, with the production of the CH(3)N isomer dominated by dynamical effects. The implications for the chemical models of the atmosphere of Titan are discussed.
Insfrán, J. F.; Ubal, S.; Di Paolo, y. J.
2016-04-01
A simplified model of a proximal convoluted tubule of an average human nephron is presented. The model considers the 2D axisymmetric flow of the luminal solution exchanging matter with the tubule walls and the peritubular fluid by means of 0D models for the epithelial cells. The tubule radius is considered to vary along the conduit due to the trans-epithelial pressure difference. The fate of more than ten typical solutes is tracked down by the model. The Navier-Stokes and Reaction-Diffusion-Advection equations (considering the electro-neutrality principle) are solved in the lumen, giving a detailed picture of the velocity, pressure and concentration fields, along with trans-membrane fluxes and tubule deformation, via coupling with the 0D model for the tubule wall. The calculations are carried out numerically by means of the finite element method. The results obtained show good agreement with those published by other authors using models that ignore the diffusive transport and disregard a detailed calculation of velocity, pressure and concentrations. This work should be seen as a first approach towards the development of a more comprehensive model of the filtration process taking place in the kidneys, which ultimately helps in devising a device that can mimic/complement the renal function.
International Nuclear Information System (INIS)
Brekke, L.; Imbo, T.D.
1992-01-01
The authors study the inequivalent quantizations of (1 + 1)-dimensional nonlinear sigma models with space manifold S 1 and target manifold X. If x is multiply connected, these models possess topological solitons. After providing a definition of spin and statistics for these solitons and demonstrating a spin-statistics correlation, we give various examples where the solitons can have exotic statistics. In some of these models, the solitons may obey a generalized version of fractional statistics called ambistatistics. In this paper the relevance of these 2d models to the statistics of vortices in (2 + 1)-dimensional spontaneously broken gauge theories is discussed. The authors close with a discussion concerning the extension of our results to higher dimensions
International Nuclear Information System (INIS)
Budiharto, Tom; Slagmolen, Pieter; Hermans, Jeroen; Maes, Frederik; Verstraete, Jan; Heuvel, Frank Van den; Depuydt, Tom; Oyen, Raymond; Haustermans, Karin
2009-01-01
Background and purpose: Currently, most available patient alignment tools based on implanted markers use manual marker matching and rigid registration transformations to measure the needed translational shifts. To quantify the particular effect of prostate gland shrinkage, implanted gold markers were tracked during a course of radiotherapy including an isotropic scaling factor to model prostate shrinkage. Materials and methods: Eight patients with prostate cancer had gold markers implanted transrectally and seven were treated with (neo) adjuvant androgen deprivation therapy. After patient alignment to skin tattoos, orthogonal electronic portal images (EPIs) were taken. A semi-automated 2D/3D marker-based registration was performed to calculate the necessary couch shifts. The registration consists of a rigid transformation combined with an isotropic scaling to model prostate shrinkage. Results: The inclusion of an isotropic shrinkage model in the registration algorithm cancelled the corresponding increase in registration error. The mean scaling factor was 0.89 ± 0.09. For all but two patients, a decrease of the isotropic scaling factor during treatment was observed. However, there was almost no difference in the translation offset between the manual matching of the EPIs to the digitally reconstructed radiographs and the semi-automated 2D/3D registration. A decrease in the intermarker distance was found correlating with prostate shrinkage rather than with random marker migration. Conclusions: Inclusion of shrinkage in the registration process reduces registration errors during a course of radiotherapy. Nevertheless, this did not lead to a clinically significant change in the proposed table translations when compared to translations obtained with manual marker matching without a scaling correction
Gao, Ming; Li, Shiwei
2017-05-01
Based on experimental data of the soybean yield and quality from 30 sampling points, a quantitative structure-activity relationship model (2D-QSAR) was established using the soil quality (elements, pH, organic matter content and cation exchange capacity) as independent variables and soybean yield or quality as the dependent variable, with SPSS software. During the modeling, the full data set (30 and 14 compounds) was divided into a training set (24 and 11 compounds) for model generation and a test set (6 and 3 compounds) for model validation. The R2 values of the resulting models and data were 0.826 and 0.808 for soybean yield and quality, respectively, and all regression coefficients were significant (P test set were 0.961 and 0.956, respectively, indicating that the models had a good predictive ability. Moreover, the Mo, Se, K, N and organic matter contents and the cation exchange capacity of soil had a positive effect on soybean production, and the B, Mo, Se, K and N contents and cation exchange coefficient had a positive effect on soybean quality. The results are instructive for enhancing soils to improve the yield and quality of soybean, and this method can also be used to study other crops or regions, providing a theoretical basis to improving the yield and quality of crops.
A continuous-time control model on production planning network ...
African Journals Online (AJOL)
A continuous-time control model on production planning network. DEA Omorogbe, MIU Okunsebor. Abstract. In this paper, we give a slightly detailed review of Graves and Hollywood model on constant inventory tactical planning model for a job shop. The limitations of this model are pointed out and a continuous time ...
Energy Technology Data Exchange (ETDEWEB)
Tsai, Tsung-Yuan; Lu, Tung-Wu; Chen, Chung-Ming; Kuo, Mei-Ying; Hsu, Horng-Chaung [Institute of Biomedical Engineering, National Taiwan University, No. 1, Sec. 1, Jen-Ai Road, Taipei 10051, Taiwan (China); Institute of Biomedical Engineering, National Taiwan University, No. 1, Sec. 1, Jen-Ai Road, Taipei 10051, Taiwan (China) and Department of Physical Therapy, China Medical University, Taichung 40402, Taiwan (China); Department of Orthopaedic Surgery, China Medical University Hospital, Taichung 40447, Taiwan (China)
2010-03-15
Purpose: Accurate measurement of the three-dimensional (3D) rigid body and surface kinematics of the natural human knee is essential for many clinical applications. Existing techniques are limited either in their accuracy or lack more realistic experimental evaluation of the measurement errors. The purposes of the study were to develop a volumetric model-based 2D to 3D registration method, called the weighted edge-matching score (WEMS) method, for measuring natural knee kinematics with single-plane fluoroscopy to determine experimentally the measurement errors and to compare its performance with that of pattern intensity (PI) and gradient difference (GD) methods. Methods: The WEMS method gives higher priority to matching of longer edges of the digitally reconstructed radiograph and fluoroscopic images. The measurement errors of the methods were evaluated based on a human cadaveric knee at 11 flexion positions. Results: The accuracy of the WEMS method was determined experimentally to be less than 0.77 mm for the in-plane translations, 3.06 mm for out-of-plane translation, and 1.13 deg. for all rotations, which is better than that of the PI and GD methods. Conclusions: A new volumetric model-based 2D to 3D registration method has been developed for measuring 3D in vivo kinematics of natural knee joints with single-plane fluoroscopy. With the equipment used in the current study, the accuracy of the WEMS method is considered acceptable for the measurement of the 3D kinematics of the natural knee in clinical applications.
Logvinov, Igor M.; Tarasov, Viktor N.
2018-03-01
Previously obtained magnetotelluric 2D models for 30 profiles made it possible to create an overview model of electric resistivity for the territory between 28°E and 36°E and between 44.5°N and 52.5°N. It allows us to distinguish a number of low resistivity objects (LRO) with resistivities lower than 100 Ω m the Earth's crust and mantle. Two regional conductivity anomalies are traced. The Kirovograd conductivity anomaly extends south to the Crimea mountains. A new regional conductivity anomaly (Konkskaya) can be distinguished along the southern slope of the Ukrainian Shield from 29° to 34°E. In addition, many local LROs have been identified. According to the modeling results, the local low resistivity objects on the East European Platform appear along fault zones activated during last 5-7 M years and the model suggests their relation to known zones of graphitization and polymetallic ore deposits. Local LROs in the Dnieper-Donets Basin correlate with the main oil and natural gas fields in this area. The depth of the anomalous objects amounts to 5-22 km. This is consistent with the hypotheses that hydrocarbon deposits are related to generation and transport zones of carbon-bearing fluids.
Discrete and Continuous Models for Partitioning Problems
Lellmann, Jan
2013-04-11
Recently, variational relaxation techniques for approximating solutions of partitioning problems on continuous image domains have received considerable attention, since they introduce significantly less artifacts than established graph cut-based techniques. This work is concerned with the sources of such artifacts. We discuss the importance of differentiating between artifacts caused by discretization and those caused by relaxation and provide supporting numerical examples. Moreover, we consider in depth the consequences of a recent theoretical result concerning the optimality of solutions obtained using a particular relaxation method. Since the employed regularizer is quite tight, the considered relaxation generally involves a large computational cost. We propose a method to significantly reduce these costs in a fully automatic way for a large class of metrics including tree metrics, thus generalizing a method recently proposed by Strekalovskiy and Cremers (IEEE conference on computer vision and pattern recognition, pp. 1905-1911, 2011). © 2013 Springer Science+Business Media New York.
Henz, D. R.; Hashino, T.; Tripoli, G. J.; Smith, E. A.
2009-12-01
This study is being conducted to examine the distribution, variability, and formation-decay processes of TTL cirrus associated with tropical deep convection using the University of Wisconsin Non-Hydrostatic modeling system (NMS). The experimental design is based on Tripoli, Hack and Kiehl (1992) which explicitly simulates the radiative-convective equilibrium of the tropical atmosphere over extended periods of weeks or months using a 2D periodic cloud resolving model. The experiment design includes a radiation parameterization to explicitly simulate radiative transfer through simulated crystals. Advanced Microphysics Prediction System (AMP) will be used to simulate microphysics by employing SHIPS (Spectral Habit Ice Prediction System) for ice, SLiPS (Spectral Liquid Prediction System) for droplets, and SAPS (Spectral Aerosol Prediction System) for aerosols. The ice scheme called SHIPS is unique in that ice particle properties (such as size, particle density, and crystal habitats) are explicitly predicted in a CRM (Hashino and Tripoli, 2007, 2008). The Advanced Microphysics Prediction System (AMPS) technology provides a particularly strong tool that effectively enables the explicit modeling of the TTL cloud microphysics and dynamical processes which has yet to be accomplished by more traditional bulk microphysics approaches.
Modelling continuing professional development in an innovative context
DEFF Research Database (Denmark)
Fink, Flemming K.
2001-01-01
subject to very fast innovation processes. Continuing Professional Development of engineering staff is therefore very important. A model for the continuing education process will be described. The elements of the model and their interaction will be discussed. Part of the modelling is based on interviews...
Modelling spatial density using continuous wavelet transforms
Indian Academy of Sciences (India)
Space debris; wavelets; Mexican hat; Laplace distribution; random search; parameter estimation. ... Author Affiliations. D Sudheer Reddy1 N Gopal Reddy2 A K Anilkumar3. Digital Mapping and Modelling Division, Advanced Data Processing Research Institute, Secunderabad 500 009, India; Department of Mathematics, ...
Modelling spatial density using continuous wavelet transforms
Indian Academy of Sciences (India)
A K ANILKUMAR3. 1Digital Mapping and Modelling Division, Advanced Data Processing Research .... probability of conjunction is very high and the miss distance between active satellite and debri object is less ... particularly helpful in tackling problems involving signal identification and detection of hidden transients (hard ...
Current Density and Continuity in Discretized Models
Boykin, Timothy B.; Luisier, Mathieu; Klimeck, Gerhard
2010-01-01
Discrete approaches have long been used in numerical modelling of physical systems in both research and teaching. Discrete versions of the Schrodinger equation employing either one or several basis functions per mesh point are often used by senior undergraduates and beginning graduate students in computational physics projects. In studying…
International Nuclear Information System (INIS)
Claret, F.; Marty, N.C.M.; Tournassat, C.; Gaboreau, S.; Burnol, A.; Chiaberge, C.; Gaucher, E.C.; Munier, I.; Cochepin, B.; Michau, N.
2010-01-01
Document available in extended abstract form only. In the context of deep repository for radioactive waste, significant use of concrete will be made. This material constitutes a compromise between properties, technical uses and costs. Within the French concepts, concrete will be used to build access structures, drifts as well as waste disposal cells and waste packages for Intermediate Level Wastes (ILW). With this design, concrete will be at the interface with either/both the host rock, Callovo-Oxfordian argillites in our case, and/or the clay plug built with swelling clay such as bentonite. Due to the chemical disequilibrium between concrete and clay, chemical reactions can modify both chemical and physical properties of these materials (e.g. mineralogical composition, diffusion coefficient...). In order to assess the long term behaviour of concrete/clay interfaces and the evolution of their properties with time, predictive modelling have to be performed. The high chemical contrast (e.g. pH or pe at the interface) often leads to problems of numerical convergence. Our own experience showed that PHREEQC is very successful in handling such difficulties in 1D geometry. PHREEQC is also able to handle 2D geometries as presented hereafter thanks to the MIX option as well as feedback on porosity thanks to the MCD option (multi component diffusion). Indeed, 2D simulation of a drift sealing concept developed by Andra was attempted using PHREEQC with the MIX option which allows the use of different transport properties in the different cells. A basic program was developed to generate this complex 2D mesh and another one to treat the outputs under TECPLOT R . The mesh is composed of 3081 cells with a refinement of 3 cm at each interface. Such a simulation was already conducted under ALLIANCES geochemistry transport tools, but in our cases the mesh refinement and the chemistry of the system are extended and the feedback on porosity is now considered. Furthermore, the new multi
Energy Technology Data Exchange (ETDEWEB)
Barroz Penteado, H.L. de
1999-01-07
The Reconcavo Basin is part of a rift formed between the Late Jurassic and the Early Cretaceous in northeastern Brazil. The objective of this thesis was the compositional modeling of petroleum generation, expulsion and migration along a cross-section in the Southern Compartment of the basin with the Temispack basin simulation software. A geochemical study of the lacustrine shales of the Gomo Member (Candelas Fm.) has been performed to determine their petroleum potential, the evolution of maturation with depth and changes in petroleum composition. Hydrogen indices of immature kerogens (400-850 mg/g TOC) were shown to be higher than those of whole rocks, thus indicating a retention of Rock-Eval pyrolysis products in the mineral matrix of these type I source rocks. Saturates (30-50% of organic extracts in the immature zone) increase both in absolute and in relative (60-80%) terms in the oil window (2000-2600 m) because of a partial secondary cracking of NSOs and aromatics. After having tested several scenarios of geodynamic evolution between the Aptian and the Oligocene, a variable thickness of post-rift sediments (maximum of 1200 m) has been shown to be necessary to calibrate maturity parameters. Petroleum migration has been modeled to understand migration pathways as well as the role of faults as drains. Thus, two petroleum migration systems have been identified for the Dom Joao and Cexis accumulations. Petroleum compositional variations have been modeled by coupling the processes of retention and secondary cracking. A good calibration of compositions was obtained with secondary cracking parameters for NSOs and aromatics which are close to those of the main primary cracking reaction of a type I kerogen, coupled with a retention of 50% of NSOs within the source rocks. (author)
Discounting Models for Outcomes over Continuous Time
DEFF Research Database (Denmark)
Harvey, Charles M.; Østerdal, Lars Peter
Events that occur over a period of time can be described either as sequences of outcomes at discrete times or as functions of outcomes in an interval of time. This paper presents discounting models for events of the latter type. Conditions on preferences are shown to be satisfied if and only if t...... if the preferences are represented by a function that is an integral of a discounting function times a scale defined on outcomes at instants of time....
Patel, Dhruvesh; Ramirez, Jorge; Srivastava, Prashant; Bray, Michaela; Han, Dawei
2017-04-01
Surat, known as the diamond city of Gujart is situated 100 km downstream of Ukai dam and near the mouth of river Tapi and affected by the flood at every alternate year. The city experienced catastrophic floods in 1933, 1959, 1968, 1970, 1994, 1998 and 2006. It is estimated that a single flood event during August 6-12, 2006 in Surat and Hazira twin-city, caused heavy damages, resulted in the death of 300 people and property damage worth € 289 million. The peak discharge of 25768 m3 s-1 release from Ukai dam was responsible for the disastrous flood in Surat city. To identifylow lying areas prone to inundation and reduce the uncertainty in flood mitigation measures, HEC-RAS based 1D/2D Couple hydrodynamic modeling is carried out for Surat city. Release from the Ukai dam and tidal level of the sea are considered for upstream and downstream boundary condition. 299 surveyed cross-sections have been considered for 1D modeling, whereas a topographic map at 0.5 m contour interval was used to produce a 5 m grid and SRTM (30 & 90 m) grid has been considered for Suart and Lower Tapi Basin (LTB). Flow is simulated under unsteady conditions, calibrated for the year 1998 and validated for the year 2006. The simulated result shows that the 9th August 18.00 hr was the worst day for Surat city and maximum 75-77 % area was under inundation. Most of the flooded area experienced 0.25 m/s water velocity with the duration of 90 hr. Due to low velocity and high duration of the flood, a low lying area within the west zone and south-west zone of the city was badly affected by the flood, whereas the south zone and south-east zone was least. Simulated results show good correlation when compared with an observed flood level map. The simulated results will be helpful to improve the flood resilience strategy at Surat city and reduce the uncertainty for flood inundation mapping for future dam releases. The present case study shows the applicability of 1D/2D coupled hydrodynamic modeling for
Directory of Open Access Journals (Sweden)
H. Y. Hussin
2012-10-01
Full Text Available The occurrence of debris flows has been recorded for more than a century in the European Alps, accounting for the risk to settlements and other human infrastructure that have led to death, building damage and traffic disruptions. One of the difficulties in the quantitative hazard assessment of debris flows is estimating the run-out behavior, which includes the run-out distance and the related hazard intensities like the height and velocity of a debris flow. In addition, as observed in the French Alps, the process of entrainment of material during the run-out can be 10–50 times in volume with respect to the initially mobilized mass triggered at the source area. The entrainment process is evidently an important factor that can further determine the magnitude and intensity of debris flows. Research on numerical modeling of debris flow entrainment is still ongoing and involves some difficulties. This is partly due to our lack of knowledge of the actual process of the uptake and incorporation of material and due the effect of entrainment on the final behavior of a debris flow. Therefore, it is important to model the effects of this key erosional process on the formation of run-outs and related intensities. In this study we analyzed a debris flow with high entrainment rates that occurred in 2003 at the Faucon catchment in the Barcelonnette Basin (Southern French Alps. The historic event was back-analyzed using the Voellmy rheology and an entrainment model imbedded in the RAMMS 2-D numerical modeling software. A sensitivity analysis of the rheological and entrainment parameters was carried out and the effects of modeling with entrainment on the debris flow run-out, height and velocity were assessed.
Kolkoori, Sanjeevareddy; Chitti Venkata, Krishnamurthy; Balasubramaniam, Krishnan
2015-01-01
This article presents an analytical approach for simulation of ultrasonic diffracted wave signals from cracks in two-dimensional geometries based on a novel Huygens-Fresnel Diffraction Model (HFDM). The model employs the frequency domain far-field displacement expressions derived by Miller and Pursey in 2D for a line source located on the free surface boundary of a semi-infinite elastic medium. At each frequency in the bandwidth of a pulsed excitation, the complex diffracted field is obtained by summation of displacements due to the unblocked virtual sources located in the section containing a vertical crack. The time-domain diffracted wave signal amplitudes in a general isotropic solid are obtained by standard Fast Fourier Transform (FFT) procedures. The wedge based finite aperture transducer refracted beam profiles were modelled by treating the finite dimension transducer as an array of line sources. The proposed model is able to evaluate back-wall signal amplitude and lateral wave signal amplitude, quantitatively. The model predicted range-dependent diffracted amplitudes from the edge of a bottom surface-breaking crack in the isotropic steel specimen were compared with Geometrical Theory of Diffraction (GTD) results. The good agreement confirms the validity of the HFDM method. The simulated ultrasonic time-of-flight diffraction (TOFD) A-scan signals for surface-breaking crack lengths 2 mm and 4 mm in a 10 mm thick aluminium specimen were compared quantitatively with the experimental results. Finally, important applications of HFDM method to the ultrasonic quantitative non-destructive evaluation are discussed. Copyright © 2014 Elsevier B.V. All rights reserved.
Model checking conditional CSL for continuous-time Markov chains
DEFF Research Database (Denmark)
Gao, Yang; Xu, Ming; Zhan, Naijun
2013-01-01
In this paper, we consider the model-checking problem of continuous-time Markov chains (CTMCs) with respect to conditional logic. To the end, we extend Continuous Stochastic Logic introduced in Aziz et al. (2000) [1] to Conditional Continuous Stochastic Logic (CCSL) by introducing a conditional p...
Sorokin, Dmitry V; Peterlik, Igor; Tektonidis, Marco; Rohr, Karl; Matula, Pavel
2018-01-01
The analysis of the pure motion of subnuclear structures without influence of the cell nucleus motion and deformation is essential in live cell imaging. In this paper, we propose a 2-D contour-based image registration approach for compensation of nucleus motion and deformation in fluorescence microscopy time-lapse sequences. The proposed approach extends our previous approach, which uses a static elasticity model to register cell images. Compared with that scheme, the new approach employs a dynamic elasticity model for the forward simulation of nucleus motion and deformation based on the motion of its contours. The contour matching process is embedded as a constraint into the system of equations describing the elastic behavior of the nucleus. This results in better performance in terms of the registration accuracy. Our approach was successfully applied to real live cell microscopy image sequences of different types of cells including image data that was specifically designed and acquired for evaluation of cell image registration methods. An experimental comparison with the existing contour-based registration methods and an intensity-based registration method has been performed. We also studied the dependence of the results on the choice of method parameters.
Shepherd, Gordon G.; Cho, Young-Min; Fomichev, Victor I.; Martynenko, Oleg V.
2016-09-01
Thermospheric atomic oxygen concentrations have been retrieved from observations by the Wind Imaging Interferometer (WINDII) O+(2P→2D) 732 and 733 nm emissions and are compared with results obtained by the Global Ultraviolet Imager (GUVI). Although the observations compared were taken ten years apart, the periods were selected on the basis of solar activity, using the Canadian Ionosphere and Atmosphere Model (C-IAM) to bridge the time gap. Results from all of these were compared with those from the Naval Research Laboratory Mass Spectrometer and Incoherent Scatter (NRLMSISE-00) model. Comparisons were made on the basis of F10.7 solar flux, day of year, local time, season, latitude and longitude. The WINDII local time variations showed enhanced values for the Northern spring season. Latitude and longitude plots showed smooth variations for NRLMSISE-00 and large variations for both WINDII and GUVI observations; in particular a depression in atomic oxygen concentration around 40 °S latitude and 100 °E longitude that is tentatively identified with a longitudinal wave 1 that does not propagate in local time but has an annual variation. The averaged values showed the WINDII values to be 0.75 that of NRLMSISE-00 compared with 0.80 for GUVI. Thus the WINDII values agreed with those of GUVI to within 6%, although taken 10 years apart.
Li, Jiazhong; Bai, Fang; Liu, Huanxiang; Gramatica, Paola
2015-12-01
The concept of ligand efficiency is defined as biological activity in each molecular size and is widely accepted throughout the drug design community. Among different LE indices, surface efficiency index (SEI) was reported to be the best one in support vector machine modeling, much better than the generally and traditionally used end-point pIC50. In this study, 2D multiple linear regression and 3D comparative molecular field analysis methods are employed to investigate the structure-activity relationships of a series of androgen receptor antagonists, using pIC50 and SEI as dependent variables to verify the influence of using different kinds of end-points. The obtained results suggest that SEI outperforms pIC50 on both MLR and CoMFA models with higher stability and predictive ability. After analyzing the characteristics of the two dependent variables SEI and pIC50, we deduce that the superiority of SEI maybe lie in that SEI could reflect the relationship between molecular structures and corresponding bioactivities, in nature, better than pIC50. This study indicates that SEI could be a more rational parameter to be optimized in the drug discovery process than pIC50. © 2015 John Wiley & Sons A/S.
Hostache, Renaud; Hissler, Christophe; Matgen, Patrick; Guignard, Cédric; Bates, Paul
2014-05-01
Recent years have seen a growing awareness for the central role that fine sediment loads play in transport and diffusion of pollutants by rivers and streams. Suspended sediment can potentially carry important amounts of nutrients and contaminants, such as trace metals among which some are recognized as Potential Harmful Elements (PHE). These threaten water quality in rivers and wetlands and soil quality in floodplains. Currently, many studies focusing on sediment transport modelling deal with marine and estuarine areas. Some studies evaluate sediment transport at basin scales and often evaluate yearly sediment fluxes using hydrologic and simplified hydraulic models. Some more theoretical studies develop and improve numerical models on the basis of physical model experiments. As a matter of fact, sediment transport modelling in small rivers at reach/floodplain scale is a rather new research field. In this study, we aim at simulating sediment transport at the floodplain scale and the single flood event scale in order to predict sediment spreading on alluvial soils. This simulation will help for the estimation of the potential pollution of soils due to the transport of PHEs by suspended sediments. The model is based upon the Telemac hydro-informatic system (i.e. dynamical coupling of Telemac-2D and Sysiphe). As empirical and semi-empirical parameters need to be calibrated for such a modelling exercise, a sensitivity analysis is proposed. In parallel to the modelling exercise, an extensive hydrological/geochemical database has been set up for two flood events. The most sensitive parameters were found to be the hydraulic friction coefficient and the sediment particle settling velocity in water. Using the two monitored hydrological events for calibration and validation, it was found that the model is able to satisfyingly predict suspended sediment and dissolved pollutant transport in the river channel. In addition, a qualitative comparison between simulated sediment
Salawu, Emmanuel Oluwatobi; Hesse, Evelyn; Stopford, Chris; Davey, Neil; Sun, Yi
2017-11-01
Better understanding and characterization of cloud particles, whose properties and distributions affect climate and weather, are essential for the understanding of present climate and climate change. Since imaging cloud probes have limitations of optical resolution, especially for small particles (with diameter < 25 μm), instruments like the Small Ice Detector (SID) probes, which capture high-resolution spatial light scattering patterns from individual particles down to 1 μm in size, have been developed. In this work, we have proposed a method using Machine Learning techniques to estimate simulated particles' orientation-averaged projected sizes (PAD) and aspect ratio from their 2D scattering patterns. The two-dimensional light scattering patterns (2DLSP) of hexagonal prisms are computed using the Ray Tracing with Diffraction on Facets (RTDF) model. The 2DLSP cover the same angular range as the SID probes. We generated 2DLSP for 162 hexagonal prisms at 133 orientations for each. In a first step, the 2DLSP were transformed into rotation-invariant Zernike moments (ZMs), which are particularly suitable for analyses of pattern symmetry. Then we used ZMs, summed intensities, and root mean square contrast as inputs to the advanced Machine Learning methods. We created one random forests classifier for predicting prism orientation, 133 orientation-specific (OS) support vector classification models for predicting the prism aspect-ratios, 133 OS support vector regression models for estimating prism sizes, and another 133 OS Support Vector Regression (SVR) models for estimating the size PADs. We have achieved a high accuracy of 0.99 in predicting prism aspect ratios, and a low value of normalized mean square error of 0.004 for estimating the particle's size and size PADs.
Applications of 2D helical vortex dynamics
DEFF Research Database (Denmark)
Okulov, Valery; Sørensen, Jens Nørkær
2010-01-01
In the paper, we show how the assumption of helical symmetry in the context of 2D helical vortices can be exploited to analyse and to model various cases of rotating flows. From theory, examples of three basic applications of 2D dynamics of helical vortices embedded in flows with helical symmetry...... of the vorticity field are addressed. These included some of the problems related to vortex breakdown, instability of far wakes behind rotors and vortex theory of ideal rotors....
Continuous Time Structural Equation Modeling with R Package ctsem
Directory of Open Access Journals (Sweden)
Charles C. Driver
2017-04-01
Full Text Available We introduce ctsem, an R package for continuous time structural equation modeling of panel (N > 1 and time series (N = 1 data, using full information maximum likelihood. Most dynamic models (e.g., cross-lagged panel models in the social and behavioural sciences are discrete time models. An assumption of discrete time models is that time intervals between measurements are equal, and that all subjects were assessed at the same intervals. Violations of this assumption are often ignored due to the difficulty of accounting for varying time intervals, therefore parameter estimates can be biased and the time course of effects becomes ambiguous. By using stochastic differential equations to estimate an underlying continuous process, continuous time models allow for any pattern of measurement occasions. By interfacing to OpenMx, ctsem combines the flexible specification of structural equation models with the enhanced data gathering opportunities and improved estimation of continuous time models. ctsem can estimate relationships over time for multiple latent processes, measured by multiple noisy indicators with varying time intervals between observations. Within and between effects are estimated simultaneously by modeling both observed covariates and unobserved heterogeneity. Exogenous shocks with different shapes, group differences, higher order diffusion effects and oscillating processes can all be simply modeled. We first introduce and define continuous time models, then show how to specify and estimate a range of continuous time models using ctsem.
Sunaryani, A.; Harsono, E.; Rustini, H. A.; Nomosatryo, S.
2018-02-01
Lake Toba is the largest lake in Indonesia utilized as a source of life-support for drinking and clean water, energy sources, aquaculture and tourism. Nowadays the water quality in Lake Toba has decreased due to the presence of excessive nutrient (nitrogen: N and phosphorus: P). This study aims to describe the spatial distribution of nutrient pollution and to develop a decision support tool for the identification and evaluation of nutrient pollution control in Lake Toba. Spatial distribution method was conducted by 2D-multi layers hydrodynamic model, while DPSIR Framework is used as a tool for the assessment. The results showed that the concentration of nutrient was low and tended to increase along the water depth, but nutrient concentration in aquaculture zones was very high and the trophic state index has reached eutrophic state. The principal anthropogenic driving forces were population growth and the development of aquaculture, livestock, agriculture, and tourism. The main environmental pressures showed that aquaculture and livestock waste are the most important nutrient sources (93% of N and 87% of P loads). State analysis showed that high nutrient concentration and increased algal growth lead to oxygen depletion. The impacts of these conditions were massive fish kills, loss of amenities and tourism value, also decreased usability of clean water supply. This study can be a useful information for decision-makers to evaluate nutrient pollution control. Nutrient pollution issue in Lake Toba requires the attention of local government and public society to maintain its sustainability.
Leveridge, Melanie; Buxton, Rachel; Argyrou, Argyrides; Francis, Peter; Leavens, Bill; West, Andy; Rees, Mike; Hardwicke, Philip; Bridges, Angela; Ratcliffe, Steven; Chung, Chun-wa
2014-02-01
Using mass spectrometry to detect enzymatic activity offers several advantages over fluorescence-based methods. Automation of sample handling and analysis using platforms such as the RapidFire (Agilent Technologies, Lexington, MA) has made these assays amenable to medium-throughput screening (of the order of 100,000 wells). However, true high-throughput screens (HTS) of large compound collections (>1 million) are still considered too time-consuming to be feasible. Here we propose a simple multiplexing strategy that can be used to increase the throughput of RapidFire, making it viable for HTS. The method relies on the ability to analyze pooled samples from several reactions simultaneously and to deconvolute their origin using "mass-tagged" substrates. Using the JmjD2d H3K9me3 demethylase as a model system, we demonstrate the practicality of this method to achieve a 4-fold increase in throughput. This was achieved without any loss of assay quality. This multiplex strategy could easily be scaled to give even greater reductions in analysis time.
International Nuclear Information System (INIS)
Adhika Junara Karunianto
2013-01-01
Geophysical investigation by geo electrical resistivity method have been done at Kompas Raya Village, Pinoh, Melawi, West Kalimantan Province. Kompas Raya Village is an area that is always a lack of water in the dry season, so the villagers are always difficult to get clean water to meet their daily needs. This study aimed to look resistivity distribution both laterally and vertically in two dimensions. The data distribution of resistivity can be used as a basis to determine the potential aquifers in the area of research. The measurement method of sounding resistivity is performed by Schlumberger Configuration. The numbers of measuring points are 30 points soundings which are divided into six survey paths each where each survey path is contained five measuring points. In this study, resistivity data processing is performed using 2D inversion modeling techniques based on data resistivity sounding. The results obtained from this study is the presence of two layers of relatively low resistivity that is each less than 30 Ohm.m and 20 Ohm.m. The first layer is interpreted as a shallow aquifer (aquifer-1) with the depth of about 20 m to 30 m, while the second layer is interpreted as the aquifer (aquifer-2) with the depth of about 90 m to 100 m. (author)
International Nuclear Information System (INIS)
Chebli, Rezki
2014-01-01
Cavitation is one of the most demanding physical phenomena influencing the performance of hydraulic machines. It is therefore important to predict correctly its inception and development, in order to quantify the performance drop it induces, and also to characterize the resulting flow instabilities. The aim of this work is to develop an unsteady 3D algorithm for the numerical simulation of cavitation in an industrial CFD solver 'Code Saturne'. It is based on a fractional step method and preserves the minimum/maximum principle of the void fraction. An implicit solver, based on a transport equation of the void fraction coupled with the Navier-Stokes equations is proposed. A specific numerical treatment of the cavitation source terms provides physical values of the void fraction (between 0 and 1) without including any artificial numerical limitation. The influence of RANS turbulence models on the simulation of cavitation on 2D geometries (Venturi and Hydrofoil) is then studied. It confirms the capability of the two-equation eddy viscosity models, k-epsilon and k-omega-SST, with the modification proposed by Reboud et al. (1998) to reproduce the main features of the unsteady sheet cavity behavior. The second order model RSM-SSG, based on the Reynolds stress transport, appears able to reproduce the highly unsteady flow behavior without including any arbitrary modification. The three-dimensional effects involved in the instability mechanisms are also analyzed. This work allows us to achieve a numerical tool, validated on complex configurations of cavitating flows, to improve the understanding of the physical mechanisms that control the three-dimensional unsteady effects involved in the mechanisms of instability. (author)
Continued development and validation of the AER two-dimensional interactive model
Ko, M. K. W.; Sze, N. D.; Shia, R. L.; Mackay, M.; Weisenstein, D. K.; Zhou, S. T.
1996-01-01
Results from two-dimensional chemistry-transport models have been used to predict the future behavior of ozone in the stratosphere. Since the transport circulation, temperature, and aerosol surface area are fixed in these models, they cannot account for the effects of changes in these quantities, which could be modified because of ozone redistribution and/or other changes in the troposphere associated with climate changes. Interactive two-dimensional models, which calculate the transport circulation and temperature along with concentrations of the chemical species, could provide answers to complement the results from three-dimension model calculations. In this project, we performed the following tasks in pursuit of the respective goals: (1) We continued to refine the 2-D chemistry-transport model; (2) We developed a microphysics model to calculate the aerosol loading and its size distribution; (3) The treatment of physics in the AER 2-D interactive model were refined in the following areas--the heating rate in the troposphere, and wave-forcing from propagation of planetary waves.
Integral-Value Models for Outcomes over Continuous Time
DEFF Research Database (Denmark)
Harvey, Charles M.; Østerdal, Lars Peter
Models of preferences between outcomes over continuous time are important for individual, corporate, and social decision making, e.g., medical treatment, infrastructure development, and environmental regulation. This paper presents a foundation for such models. It shows that conditions on prefere...... on preferences between real- or vector-valued outcomes over continuous time are satisfied if and only if the preferences are represented by a value function having an integral form......Models of preferences between outcomes over continuous time are important for individual, corporate, and social decision making, e.g., medical treatment, infrastructure development, and environmental regulation. This paper presents a foundation for such models. It shows that conditions...
Continuous time modeling of panel data by means of SEM
Oud, J.H.L.; Delsing, M.J.M.H.; Montfort, C.A.G.M.; Oud, J.H.L.; Satorra, A.
2010-01-01
After a brief history of continuous time modeling and its implementation in panel analysis by means of structural equation modeling (SEM), the problems of discrete time modeling are discussed in detail. This is done by means of the popular cross-lagged panel design. Next, the exact discrete model
Continuous time structural equation modeling with R package ctsem
Driver, C.C.; Oud, J.H.L.; Völkle, M.C.
2017-01-01
We introduce ctsem, an R package for continuous time structural equation modeling of panel (N > 1) and time series (N = 1) data, using full information maximum likelihood. Most dynamic models (e.g., cross-lagged panel models) in the social and behavioural sciences are discrete time models. An
Semini, Geo; Hildmann, Annette; Klein, Andreas; Lucka, Lothar; Schön, Margarete; Schön, Michael P; Shmanai, Vadim; Danker, Kerstin
2014-02-01
In cutaneous inflammatory diseases, such as psoriasis, atopic dermatitis and allergic contact dermatitis, skin-infiltrating T lymphocytes and dendritic cells modulate keratinocyte function via the secretion of pro-inflammatory cytokines. Keratinocytes then produce mediators that recruit and activate immune cells and amplify the inflammatory response. These pathophysiological tissue changes are caused by altered gene expression and the proliferation and maturation of dermal and epidermal cells. We recently demonstrated that the glycosidated phospholipid Ino-C2-PAF down-regulates a plethora of gene products associated with innate and acquired immune responses and inflammation in the HaCaT keratinocyte cell line. To further evaluate the influence of Ino-C2-PAF we established an in vitro 2D-model of epidermal inflammation. The induction of inflammation and the impact of Ino-C2-PAF were assessed in this system using a genome-wide microarray analysis. In addition, the expression of selected genes was validated using qRT-PCR and flow cytometry. Treatment of the keratinocytes with a mix of proinflammatory cytokines resulted in transcriptional effects on a variety of genes involved in cutaneous inflammation and immunity, while additional treatment with Ino-C2-PAF counteracted the induction of many of these genes. Remarkably, Ino-C2-PAF suppressed the expression of a group of targets that are implicated in antigen processing and presentation, including MHC molecules. Thus, it is conceivable that Ino-C2-PAF possess therapeutic potential for inflammatory skin disorders, such as psoriasis and allergic contact dermatitis. Copyright © 2013 Elsevier Inc. All rights reserved.
Pawlick, R; Gala-Lopez, B; Pepper, A R; McCall, M; Ziff, O; Shapiro, A M J
2014-10-01
Islet transplantation is an effective means of treating severe type 1 diabetes in patients with life-threatening hypoglycemia. Improvements in glycemic control with correction of HbA1C enhance quality of life irrespective of insulin independence. By antagonizing the Natural Killer Group 2, member D (NKG2D) receptor expression on NK and CD8+ T cells, in combination with blocking CTLA-4 binding sites, we demonstrate a significant delay of graft rejection in islet allotransplant. Anti-NKG2D combined with CTLA-4 Ig (n = 15) results in prolonged allograft survival, with 84.6 ± 10% of the recipients displaying insulin independence compared to controls (n = 10, p < 0.001). The effect of combination therapy on graft survival is superior to treatments alone (CTLA-4 Ig vs. combination p = 0.024, anti-NKG2D vs. combination p < 0.001) indicating an interaction between these pathways. In addition, combination treatment also improves glucose tolerance when compared to controls (n = 10, p = 0.018). Histologically, NKG2D+ cells were significantly decreased within the allograft after 7 days of combination treatment (n = 6, p = 0.029). T cell proliferation was significantly reduced with anti-NKG2D therapy and CD8+ T cell daughter fractions were also significantly decreased with mAb and combination treatment when measured by in vitro mixed lymphocyte reaction (n = 5, p = 0.015, p = 0.005 and p = 0.048). These results demonstrate that inhibition of NKG2D receptors and costimulatory pathways enhance islet allograft survival. © Copyright 2014 The American Society of Transplantation and the American Society of Transplant Surgeons.
Baiz, Carlos R; Schach, Denise; Tokmakoff, Andrei
2014-07-28
We describe a microscope for measuring two-dimensional infrared (2D IR) spectra of heterogeneous samples with μm-scale spatial resolution, sub-picosecond time resolution, and the molecular structure information of 2D IR, enabling the measurement of vibrational dynamics through correlations in frequency, time, and space. The setup is based on a fully collinear "one beam" geometry in which all pulses propagate along the same optics. Polarization, chopping, and phase cycling are used to isolate the 2D IR signals of interest. In addition, we demonstrate the use of vibrational lifetime as a contrast agent for imaging microscopic variations in molecular environments.
2016-05-31
Distribution Unlimited UU UU UU UU 31-05-2016 15-Apr-2014 14-Jan-2015 Final Report: Technical Topic 3.2.2.d Bayesian and Non- parametric Statistics...of Papers published in non peer-reviewed journals: Final Report: Technical Topic 3.2.2.d Bayesian and Non- parametric Statistics: Integration of Neural...Transfer N/A Number of graduating undergraduates who achieved a 3.5 GPA to 4.0 (4.0 max scale ): Number of graduating undergraduates funded by a DoD funded
Modeling irregularly spaced residual series as a continuous stochastic process
Von Asmuth, J.R.; Bierkens, M.F.P.
2005-01-01
In this paper, the background and functioning of a simple but effective continuous time approach for modeling irregularly spaced residual series is presented. The basic equations were published earlier by von Asmuth et al. (2002), who used them as part of a continuous time transfer function noise
Eigenfunction statistics for Anderson model with Hölder continuous ...
Indian Academy of Sciences (India)
continuous (0 < α ≤ 1) single site distribution. In localized regime, we study the distri- bution of eigenfunctions in space and energy simultaneously. In a certain scaling limit, we prove limit points are Poisson. Keywords. Anderson model; Hölder continuous measure; Poisson statistics. 2010 Mathematics Subject Classification ...
Accurate path integration in continuous attractor network models of grid cells.
Directory of Open Access Journals (Sweden)
Yoram Burak
2009-02-01
Full Text Available Grid cells in the rat entorhinal cortex display strikingly regular firing responses to the animal's position in 2-D space and have been hypothesized to form the neural substrate for dead-reckoning. However, errors accumulate rapidly when velocity inputs are integrated in existing models of grid cell activity. To produce grid-cell-like responses, these models would require frequent resets triggered by external sensory cues. Such inadequacies, shared by various models, cast doubt on the dead-reckoning potential of the grid cell system. Here we focus on the question of accurate path integration, specifically in continuous attractor models of grid cell activity. We show, in contrast to previous models, that continuous attractor models can generate regular triangular grid responses, based on inputs that encode only the rat's velocity and heading direction. We consider the role of the network boundary in the integration performance of the network and show that both periodic and aperiodic networks are capable of accurate path integration, despite important differences in their attractor manifolds. We quantify the rate at which errors in the velocity integration accumulate as a function of network size and intrinsic noise within the network. With a plausible range of parameters and the inclusion of spike variability, our model networks can accurately integrate velocity inputs over a maximum of approximately 10-100 meters and approximately 1-10 minutes. These findings form a proof-of-concept that continuous attractor dynamics may underlie velocity integration in the dorsolateral medial entorhinal cortex. The simulations also generate pertinent upper bounds on the accuracy of integration that may be achieved by continuous attractor dynamics in the grid cell network. We suggest experiments to test the continuous attractor model and differentiate it from models in which single cells establish their responses independently of each other.
Constrained optimization with a continuous Hopfield-Lagrange model
J.H. van den Berg (Jan); J.C. Bioch (Cor)
1993-01-01
textabstractIn this paper, a generalized Hopfield model with continuous neurons using Lagrange multipliers, originally introduced Wacholder, Han &Mann [1989], is thoroughly analysed. We have termed the model the Hopfield-Lagrange model. It can be used to resolve constrained optimization problems. In
Directory of Open Access Journals (Sweden)
CODREAN Marius
2016-05-01
Full Text Available The purpose of this optimization is the identification of optimal parameters for processing the workpiece (the OLC45 steel bar, using inductive heating in volume. Flux 9.3.2 software, in 2D plan, has been employed in order to perform numerical simulations, while Minitab software has been used to determine optimal parameters.
Dimensional reduction of the chiral-continuous Gross-Neveu model
Energy Technology Data Exchange (ETDEWEB)
Ananos, G.N.J.; Malbouisson, A.P.C.; Silva Neto, M.B.; Svaiter, N.F
1997-11-01
We study the finite-temperature phase transition of the generalized Gross-Neveu model with continuous chiral symmetry in 2< d{<=} 4 euclidean dimensions. The critical exponents are computed to the leading order in the 1/N expansion at both zero and finite temperatures. A dimensionally reduced theory is obtained after the introduction of thermal counterterms necessary to cancel thermal divergences that arise in the limit of high temperature. Although at zero temperature we have an infinitely and continuously degenerate vacuum state, we show that at finite temperature this degeneracy is discrete and, depending on the values of the bare parameters, we may have either total or partial restoration of symmetry. Finally we determine the universality class of the reduced theory by a simple analysis of the infrared structure of thermodynamic quantities computed using the reduced action as starting point. (author) 18 refs.
Zhang, Han; Wang, Junzhuan; Hasan, Tawfique; Bao, Qiaoliang
2018-01-01
The emergence of graphene and graphene-like two dimensional (2D) materials has attracted a strong interest from the photonics community in recent decade. Apart from zero-gap graphene, insulating hexagonal boron nitride and semiconducting transition metal dichalcogenides and phosphorene/black phosphorus are being intensively investigated because of their fascinating photonic and optoelectronic properties. Compared to traditional bulk photonic materials such as Gallium Arsenide (GaAs) and Silicon (Si), 2D materials exhibit many unique properties important for device applications in nanophotonics. Firstly, quantum confinement in the direction perpendicular to 2D plane leads to novel electronic and optical features that are distinctively different from their bulk counterparts. Secondly, their surfaces are naturally passivated without any dangling bonds making them readily compatible for integration with photonic structures such as waveguides and cavities. It is also possible to construct vertical hetero-structures by using different 2D materials, without considering lattice mismatch issues that are common in bulk semiconductors. This is because the 2D layers with different lattice constants in heterostructures are only weakly bounded by van der Waals force. Thirdly, despite being atomically thin, many 2D materials interact very strongly with light.
Park, Yongeun; Pachepsky, Yakov A.; Cho, Kyung Hwa; Jeon, Dong Jin; Kim, Joon Ha
2015-10-01
To control algal blooms, the stressor-response relationships between water quality metrics, environmental variables, and algal growth need to be better understood and modeled. Machine-learning methods have been suggested as means to express the stressor-response relationships that are found when applying mechanistic water quality models. The objective of this work was to evaluate the efficiency of regression trees in the development of a stressor-response model for chlorophyll-a (Chl-a) concentrations, using the results from site-specific mechanistic water quality modeling. The 2-dimensional hydrodynamic and water quality model (CE-QUAL-W2) model was applied to simulate water quality using four-year observational data and additional scenarios of air temperature increases for the Yeongsan Reservoir in South Korea. Regression tree modeling was applied to the results of these simulations. Given the well-expressed seasonality in the simulated Chl-a dynamics, separate regression trees were developed for months from May to September. The regression trees provided a reasonably accurate representation of the stressor-response dependence generated by the CE-QUAL-W2 model. Different stressors were then selected as split variables for different months, and, in most cases, splits by the same stressor variable yielded the same correlation sign between the variable and the Chl-a concentration. Compared to physical variables, nutrient content appeared to better predict Chl-a responses. The highest Chl-a temperature sensitivities were found for May and June. Regression tree splits based on ammonium concentration resulted in a consistent trend of greater sensitivity in the groups of samples with higher ammonium concentrations. Regression tree models provided a transparent visual representation of the stressor-response relationships for Chl-a and its sensitivity. Overall, the representation of relationships using classification and regression tools can be considered a useful
Orthotropic Piezoelectricity in 2D Nanocellulose.
García, Y; Ruiz-Blanco, Yasser B; Marrero-Ponce, Yovani; Sotomayor-Torres, C M
2016-10-06
The control of electromechanical responses within bonding regions is essential to face frontier challenges in nanotechnologies, such as molecular electronics and biotechnology. Here, we present Iβ-nanocellulose as a potentially new orthotropic 2D piezoelectric crystal. The predicted in-layer piezoelectricity is originated on a sui-generis hydrogen bonds pattern. Upon this fact and by using a combination of ab-initio and ad-hoc models, we introduce a description of electrical profiles along chemical bonds. Such developments lead to obtain a rationale for modelling the extended piezoelectric effect originated within bond scales. The order of magnitude estimated for the 2D Iβ-nanocellulose piezoelectric response, ~pm V -1 , ranks this material at the level of currently used piezoelectric energy generators and new artificial 2D designs. Such finding would be crucial for developing alternative materials to drive emerging nanotechnologies.
Orthotropic Piezoelectricity in 2D Nanocellulose
García, Y.; Ruiz-Blanco, Yasser B.; Marrero-Ponce, Yovani; Sotomayor-Torres, C. M.
2016-10-01
The control of electromechanical responses within bonding regions is essential to face frontier challenges in nanotechnologies, such as molecular electronics and biotechnology. Here, we present Iβ-nanocellulose as a potentially new orthotropic 2D piezoelectric crystal. The predicted in-layer piezoelectricity is originated on a sui-generis hydrogen bonds pattern. Upon this fact and by using a combination of ab-initio and ad-hoc models, we introduce a description of electrical profiles along chemical bonds. Such developments lead to obtain a rationale for modelling the extended piezoelectric effect originated within bond scales. The order of magnitude estimated for the 2D Iβ-nanocellulose piezoelectric response, ~pm V-1, ranks this material at the level of currently used piezoelectric energy generators and new artificial 2D designs. Such finding would be crucial for developing alternative materials to drive emerging nanotechnologies.
A stochastic surplus production model in continuous time
DEFF Research Database (Denmark)
Pedersen, Martin Wæver; Berg, Casper Willestofte
2017-01-01
surplus production model in continuous time (SPiCT), which in addition to stock dynamics also models the dynamics of the fisheries. This enables error in the catch process to be reflected in the uncertainty of estimated model parameters and management quantities. Benefits of the continuous-time state......Surplus production modelling has a long history as a method for managing data-limited fish stocks. Recent advancements have cast surplus production models as state-space models that separate random variability of stock dynamics from error in observed indices of biomass. We present a stochastic...... and improve estimation of reference points relative to discrete-time analysis of aggregated annual data. Finally, subannual data from five North Sea stocks are analysed with particular focus on using residual analysis to diagnose model insufficiencies and identify necessary model extensions such as robust...
Assimilation of Spatially Sparse In Situ Soil Moisture Networks into a Continuous Model Domain
Gruber, A.; Crow, W. T.; Dorigo, W. A.
2018-02-01
Growth in the availability of near-real-time soil moisture observations from ground-based networks has spurred interest in the assimilation of these observations into land surface models via a two-dimensional data assimilation system. However, the design of such systems is currently hampered by our ignorance concerning the spatial structure of error afflicting ground and model-based soil moisture estimates. Here we apply newly developed triple collocation techniques to provide the spatial error information required to fully parameterize a two-dimensional (2-D) data assimilation system designed to assimilate spatially sparse observations acquired from existing ground-based soil moisture networks into a spatially continuous Antecedent Precipitation Index (API) model for operational agricultural drought monitoring. Over the contiguous United States (CONUS), the posterior uncertainty of surface soil moisture estimates associated with this 2-D system is compared to that obtained from the 1-D assimilation of remote sensing retrievals to assess the value of ground-based observations to constrain a surface soil moisture analysis. Results demonstrate that a fourfold increase in existing CONUS ground station density is needed for ground network observations to provide a level of skill comparable to that provided by existing satellite-based surface soil moisture retrievals.
Models of maternity care: evidence for midwifery continuity of care.
Homer, Caroline Se
2016-10-17
There has been substantial reform in the past decade in the provision of maternal and child health services, and specifically regarding models of maternity care. Increasingly, midwives are working together in small groups to provide midwife-led continuity of care. This article reviews the current evidence for models of maternity care that provide midwifery continuity of care, in terms of their impact on clinical outcomes, the views of midwives and childbearing women, and health service costs. A systematic review of midwife-led continuity of care models identified benefits for women and babies, with no adverse effects. Non-randomised studies have shown benefits of midwifery continuity of care for specific groups, such as Aboriginal and Torres Strait Islander women. There are also benefits for midwives, including high levels of job satisfaction and less occupational burnout. Implementing midwifery continuity of care in public and private settings in Australia has been challenging, despite the evidence in its favour and government policy documents that support it. A reorganisation of the way maternity services are provided in Australia is required to ensure that women across the country can access this model of care. Critical to such reform is collaboration with obstetricians, general practitioners, paediatricians and other medical professionals involved in the care of pregnant women, as well as professional respect for the central role of midwives in the provision of maternity care. More research is needed into ways to ensure that all childbearing women can access midwifery continuity of care.
Modeling of water treatment plant using timed continuous Petri nets
Nurul Fuady Adhalia, H.; Subiono, Adzkiya, Dieky
2017-08-01
Petri nets represent graphically certain conditions and rules. In this paper, we construct a model of the Water Treatment Plant (WTP) using timed continuous Petri nets. Specifically, we consider that (1) the water pump always active and (2) the water source is always available. After obtaining the model, the flow through the transitions and token conservation laws are calculated.
A Quasispecies Continuous Contact Model in a Critical Regime
Kondratiev, Yuri; Pirogov, Sergey; Zhizhina, Elena
2016-04-01
We study a new non-equilibrium dynamical model: a marked continuous contact model in d-dimensional space (d ge 3). We prove that for certain values of rates (the critical regime) this system has the one-parameter family of invariant measures labelled by the spatial density of particles. Then we prove that the process starting from the marked Poisson measure converges to one of these invariant measures. In contrast with the continuous contact model studied earlier in Kondratiev (Infin Dimens Anal Quantum Probab Relat Top 11(2):231-258, 2008), now the spatial particle density is not a conserved quantity.
CONTINUOUS MODELING OF FOREIGN EXCHANGE RATE OF USD VERSUS TRY
Directory of Open Access Journals (Sweden)
Yakup Arı
2011-01-01
Full Text Available This study aims to construct continuous-time autoregressive (CAR model and continuous-time GARCH (COGARCH model from discrete time data of foreign exchange rate of United States Dollar (USD versus Turkish Lira (TRY. These processes are solutions to stochastic differential equation Lévy-driven processes. We have shown that CAR(1 and COGARCH(1,1 processes are proper models to represent foreign exchange rate of USD and TRY for different periods of time February 2002- June 2010.
Modelling continuing professional development in an innovative context
DEFF Research Database (Denmark)
Fink, Flemming K.
2001-01-01
Being one step ahead of your competitors with incorporation of new knowledge in the products puts focus on the importance of human resources as a significant resource for industrial development. A major competitive parameter in knowledge society is engineering competence, especially in the industry...... subject to very fast innovation processes. Continuing Professional Development of engineering staff is therefore very important. A model for the continuing education process will be described. The elements of the model and their interaction will be discussed. Part of the modelling is based on interviews...
Czech Academy of Sciences Publication Activity Database
Chankin, A.V.; Coster, D.P.; Asakura, N.; Bonnin, X.; Conway, G.D.; Corrigan, G.; Erents, S. K.; Fundameski, W.; Horáček, Jan; Kallenbach, A.; Kaufmann, M.; Konz, C.; Lackner, K.; Müller, H. W.; Neuhauser, J.; Pitts, R.A.; Wischmeier, M.
2007-01-01
Roč. 47, č. 5 (2007), s. 479-489 ISSN 0029-5515 Grant - others:-(XE) European Training fellowships and Grants (Euratom), EDGE TURB Institutional research plan: CEZ:AV0Z20430508 Keywords : tokamaks * plasma * scrape-off layer * radial electric fields * TCV * JET * AUG * JT-60U * EDGE 2D-Nimbus * SOLPS Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.278, year: 2007
A FPC-ROOT Algorithm for 2D-DOA Estimation in Sparse Array
Directory of Open Access Journals (Sweden)
Wenhao Zeng
2016-01-01
Full Text Available To improve the performance of two-dimensional direction-of-arrival (2D DOA estimation in sparse array, this paper presents a Fixed Point Continuation Polynomial Roots (FPC-ROOT algorithm. Firstly, a signal model for DOA estimation is established based on matrix completion and it can be proved that the proposed model meets Null Space Property (NSP. Secondly, left and right singular vectors of received signals matrix are achieved using the matrix completion algorithm. Finally, 2D DOA estimation can be acquired through solving the polynomial roots. The proposed algorithm can achieve high accuracy of 2D DOA estimation in sparse array, without solving autocorrelation matrix of received signals and scanning of two-dimensional spectral peak. Besides, it decreases the number of antennas and lowers computational complexity and meanwhile avoids the angle ambiguity problem. Computer simulations demonstrate that the proposed FPC-ROOT algorithm can obtain the 2D DOA estimation precisely in sparse array.
Ritzinger, B. T.; Glen, J. M. G.; Athens, N. D.; Denton, K. M.; Bouligand, C.
2015-12-01
Regionally continuous Cenoz