Bíscaro, Helton H; Nunes, Fátima L S; Dos Santos Oliveira, Jéssica; Pereira, Gustavo R
2016-10-01
Data structures have been explored for several domains of computer applications in order to ensure efficiency in the data store and retrieval. However, data structures can present different behavior depending on applications that they are being used. Three-dimensional interactive environments offered by techniques of Virtual Reality require operations of loading and manipulating objects in real time, where realism and response time are two important requirements. Efficient representation of geometrical models plays an important part so that the simulation may become real. In this paper, we present the implementation and the comparison of two topologically efficient data structures - Compact Half-Edge and Mate-Face - for the representation of objects for three-dimensional interactive environments. The structures have been tested at different conditions of processors and RAM memories. The results show that both these structures can be used in an efficient manner. Mate-Face structure has shown itself to be more efficient for the manipulation of neighborhood relationships and the Compact Half-Edge was more efficient for loading of the geometric models. We also evaluated the data structures embedded in applications of biopsy simulation using virtual reality, considering a deformation simulation method applied in virtual human organs. The results showed that their use allows the building of applications considering objects with high resolutions (number of vertices), without significant impact in the time spent in the simulation. Therefore, their use contributes for the construction of more realistic simulators. Copyright © 2016 Elsevier Inc. All rights reserved.
International Nuclear Information System (INIS)
Sawan, M.; Wilson, P.; El-Guebaly, L.; Henderson, D.; Sviatoslavsky, G.; Bohm, T.; Kiedrowski, B.; Ibrahim, A.; Smith, B.; Slaybaugh, R.; Tautges, T.
2007-01-01
Fusion systems are, in general, geometrically complex requiring detailed three-dimensional (3-D) nuclear analysis. This analysis is required to address tritium self-sufficiency, nuclear heating, radiation damage, shielding, and radiation streaming issues. To facilitate such calculations, we developed an innovative computational tool that is based on the continuous energy Monte Carlo code MCNP and permits the direct use of CAD-based solid models in the ray-tracing. This allows performing the neutronics calculations in a model that preserves the geometrical details without any simplification, eliminates possible human error in modeling the geometry for MCNP, and allows faster design iterations. In addition to improving the work flow for simulating complex 3- D geometries, it allows a richer representation of the geometry compared to the standard 2nd order polynomial representation. This newly developed tool has been successfully tested for a detailed 40 degree sector benchmark of the International Thermonuclear Experimental Reactor (ITER). The calculations included determining the poloidal variation of the neutron wall loading, flux and nuclear heating in the divertor components, nuclear heating in toroidal field coils, and radiation streaming in the mid-plane port. The tool has been applied to perform 3-D nuclear analysis for several fusion designs including the ARIES Compact Stellarator (ARIES-CS), the High Average Power Laser (HAPL) inertial fusion power plant, and ITER first wall/shield (FWS) modules. The ARIES-CS stellarator has a first wall shape and a plasma profile that varies toroidally within each field period compared to the uniform toroidal shape in tokamaks. Such variation cannot be modeled analytically in the standard MCNP code. The impact of the complex helical geometry and the non-uniform blanket and divertor on the overall tritium breeding ratio and total nuclear heating was determined. In addition, we calculated the neutron wall loading variation in
Geometric actions for three-dimensional gravity
Barnich, G.; González, H. A.; Salgado-Rebolledo, P.
2018-01-01
The solution space of three-dimensional asymptotically anti-de Sitter or flat Einstein gravity is given by the coadjoint representation of two copies of the Virasoro group in the former and the centrally extended BMS3 group in the latter case. Dynamical actions that control these solution spaces are usually constructed by starting from the Chern–Simons formulation and imposing all boundary conditions. In this note, an alternative route is followed. We study in detail how to derive these actions from a group-theoretical viewpoint by constructing geometric actions for each of the coadjoint orbits, including the appropriate Hamiltonians. We briefly sketch relevant generalizations and potential applications beyond three-dimensional gravity.
Fractal and prefractal geometric models have substantial potential of contributing to the analysis of flow and transport in porous media such as soils and reservoir rocks. In this study, geometric and hydrodynamic parameters of saturated 3D mass and pore-solid prefractal porous media were characteri...
Development of three dimensional solid modeler
International Nuclear Information System (INIS)
Zahoor, R.M.A.
1999-01-01
The work presented in this thesis is aimed at developing a three dimensional solid modeler employing computer graphics techniques using C-Language. Primitives have been generated, by combination of plane surfaces, for various basic geometrical shapes including cylinder, cube and cone. Back face removal technique for hidden surface removal has also been incorporated. Various transformation techniques such as scaling, translation, and rotation have been included for the object animation. Three dimensional solid modeler has been created by the union of two primitives to demonstrate the capabilities of the developed program. (author)
Three-dimensional geometric analysis of felid limb bone allometry.
Directory of Open Access Journals (Sweden)
Michael Doube
Full Text Available Studies of bone allometry typically use simple measurements taken in a small number of locations per bone; often the midshaft diameter or joint surface area is compared to body mass or bone length. However, bones must fulfil multiple roles simultaneously with minimum cost to the animal while meeting the structural requirements imposed by behaviour and locomotion, and not exceeding its capacity for adaptation and repair. We use entire bone volumes from the forelimbs and hindlimbs of Felidae (cats to investigate regional complexities in bone allometry.Computed tomographic (CT images (16435 slices in 116 stacks were made of 9 limb bones from each of 13 individuals of 9 feline species ranging in size from domestic cat (Felis catus to tiger (Panthera tigris. Eleven geometric parameters were calculated for every CT slice and scaling exponents calculated at 5% increments along the entire length of each bone. Three-dimensional moments of inertia were calculated for each bone volume, and spherical radii were measured in the glenoid cavity, humeral head and femoral head. Allometry of the midshaft, moments of inertia and joint radii were determined. Allometry was highly variable and related to local bone function, with joint surfaces and muscle attachment sites generally showing stronger positive allometry than the midshaft.Examining whole bones revealed that bone allometry is strongly affected by regional variations in bone function, presumably through mechanical effects on bone modelling. Bone's phenotypic plasticity may be an advantage during rapid evolutionary divergence by allowing exploitation of the full size range that a morphotype can occupy. Felids show bone allometry rather than postural change across their size range, unlike similar-sized animals.
Three-dimensional geometric analysis of felid limb bone allometry.
Doube, Michael; Wiktorowicz-Conroy, Alexis; Conroy, Alexis Wiktorowicz; Christiansen, Per; Hutchinson, John R; Shefelbine, Sandra
2009-01-01
Studies of bone allometry typically use simple measurements taken in a small number of locations per bone; often the midshaft diameter or joint surface area is compared to body mass or bone length. However, bones must fulfil multiple roles simultaneously with minimum cost to the animal while meeting the structural requirements imposed by behaviour and locomotion, and not exceeding its capacity for adaptation and repair. We use entire bone volumes from the forelimbs and hindlimbs of Felidae (cats) to investigate regional complexities in bone allometry. Computed tomographic (CT) images (16435 slices in 116 stacks) were made of 9 limb bones from each of 13 individuals of 9 feline species ranging in size from domestic cat (Felis catus) to tiger (Panthera tigris). Eleven geometric parameters were calculated for every CT slice and scaling exponents calculated at 5% increments along the entire length of each bone. Three-dimensional moments of inertia were calculated for each bone volume, and spherical radii were measured in the glenoid cavity, humeral head and femoral head. Allometry of the midshaft, moments of inertia and joint radii were determined. Allometry was highly variable and related to local bone function, with joint surfaces and muscle attachment sites generally showing stronger positive allometry than the midshaft. Examining whole bones revealed that bone allometry is strongly affected by regional variations in bone function, presumably through mechanical effects on bone modelling. Bone's phenotypic plasticity may be an advantage during rapid evolutionary divergence by allowing exploitation of the full size range that a morphotype can occupy. Felids show bone allometry rather than postural change across their size range, unlike similar-sized animals.
Discretization model for nonlinear dynamic analysis of three dimensional structures
International Nuclear Information System (INIS)
Hayashi, Y.
1982-12-01
A discretization model for nonlinear dynamic analysis of three dimensional structures is presented. The discretization is achieved through a three dimensional spring-mass system and the dynamic response obtained by direct integration of the equations of motion using central diferences. First the viability of the model is verified through the analysis of homogeneous linear structures and then its performance in the analysis of structures subjected to impulsive or impact loads, taking into account both geometrical and physical nonlinearities is evaluated. (Author) [pt
Three-Dimensional Ocean Noise Modeling
2015-03-01
realistic and complex three-dimensional bathymetry. This is achieved by using a parabolic equation [PE) propagation model and the reciprocity principle...explain the horizontal noise directionality observed in the Tonga Trench [Barclay, 2014], which was found not to be a 3D effect, but rather due to...modeled noise arriving on the axis of the canyon has significantly perturbed zero-crossings when compared to the equivalent Nx2D result. Theoretical
Robot vision based on three-dimensional model
International Nuclear Information System (INIS)
Shirai, Yoshiaki
1985-01-01
In order that robots recognize objects, the models of the objects are required. If there is not any constraint about an object scene, it is desirable that robot vision has the three-dimensional models of the things composing the scene. Since the preparation of three-dimensional models takes much time, here, the utilization of the geometrical models made by CAD is proposed. Besides, when the description of a scene and three-dimensional models are compared, to attempt the comparison with all attitudes of respective models is not efficient, therefore, stratum-wise comparison was proposed. As concrete examples, when input information is only in the direction of a part of surfaces such as lustrous bodies, when information can be obtained in all the directions of the surfaces of a body visible by a photometric stereo, and when complete three dimensional information is obtained by a distance-measuring instrument, the techniques of object recognition are described. In all cases, by carrying out the stratum-wise comparison based on three-dimensional models, the efficient and generalized object recognition was able to be achieved. (Kako, I.)
Three-dimensional modeler for animated images display system
International Nuclear Information System (INIS)
Boubekeur, Rania
1987-01-01
The mv3d software allows the modeling and display of three dimensional objects in interpretative mode with animation possibility in real time. This system is intended for a graphical extension of a FORTH interpreter (implemented by CEA/IRDI/D.LETI/DEIN) in order to control a specific hardware (3.D card designed and implemented by DEIN) allowing the generation of three dimensional objects. The object description is carried out with a specific graphical language integrated in the FORTH interpreter. Objects are modeled using elementary solids called basic forms (cube, cone, cylinder...) assembled with classical geometric transformations (rotation, translation and scaling). These basic forms are approximated by plane polygonal facets further divided in triangles. Coordinates of the summits of triangles constitute the geometrical data. These are sent to the 3.D. card for processing and display. Performed processing are: geometrical transformations on display, hidden surface elimination, shading and clipping. The mv3d software is not an entire modeler but a simple, modular and extensible tool, to which other specific functions may be easily added such as: robots motion, collisions... (author) [fr
DEFF Research Database (Denmark)
Yoon, Gil Ho; Joung, Young Soo; Kim, Yoon Young
2005-01-01
The topology design optimization of “three-dimensional geometrically-nonlinear” continuum structures is still a difficult problem not only because of its problem size but also the occurrence of unstable continuum finite elements during the design optimization. To overcome this difficulty, the ele...
Huang, Na; Liu, Richeng; Jiang, Yujing; Li, Bo; Yu, Liyuan
2018-03-01
While shear-flow behavior through fractured media has been so far studied at single fracture scale, a numerical analysis of the shear effect on the hydraulic response of 3D crossed fracture model is presented. The analysis was based on a series of crossed fracture models, in which the effects of fracture surface roughness and shear displacement were considered. The rough fracture surfaces were generated using the modified successive random additions (SRA) algorithm. The shear displacement was applied on one fracture, and at the same time another fracture shifted along with the upper and lower surfaces of the sheared fracture. The simulation results reveal the development and variation of preferential flow paths through the model during the shear, accompanied by the change of the flow rate ratios between two flow planes at the outlet boundary. The average contact area accounts for approximately 5-27% of the fracture planes during shear, but the actual calculated flow area is about 38-55% of the fracture planes, which is much smaller than the noncontact area. The equivalent permeability will either increase or decrease as shear displacement increases from 0 to 4 mm, depending on the aperture distribution of intersection part between two fractures. When the shear displacement continuously increases by up to 20 mm, the equivalent permeability increases sharply first, and then keeps increasing with a lower gradient. The equivalent permeability of rough fractured model is about 26-80% of that calculated from the parallel plate model, and the equivalent permeability in the direction perpendicular to shear direction is approximately 1.31-3.67 times larger than that in the direction parallel to shear direction. These results can provide a fundamental understanding of fluid flow through crossed fracture model under shear.
Directory of Open Access Journals (Sweden)
2006-01-01
Full Text Available In a wireless ad hoc network, messages are transmitted, received, and forwarded in a finite geometrical region and the transmission of messages is highly dependent on the locations of the nodes. Therefore the study of geometrical relationship between nodes in wireless ad hoc networks is of fundamental importance in the network architecture design and performance evaluation. However, most previous works concentrated on the networks deployed in the two-dimensional region or in the infinite three-dimensional space, while in many cases wireless ad hoc networks are deployed in the finite three-dimensional space. In this paper, we analyze the geometrical characteristics of the three-dimensional wireless ad hoc network in a finite space in the framework of random graph and deduce an expression to calculate the distance probability distribution between network nodes that are independently and uniformly distributed in a finite cuboid space. Based on the theoretical result, we present some meaningful results on the finite three-dimensional network performance, including the node degree and the max-flow capacity. Furthermore, we investigate some approximation properties of the distance probability distribution function derived in the paper.
Energy Technology Data Exchange (ETDEWEB)
Binotti, M.; Zhu, G.; Gray, A.; Manzollini, G.
2012-04-01
An analytical approach, as an extension of one newly developed method -- First-principle OPTical Intercept Calculation (FirstOPTIC) -- is proposed to treat the geometrical impact of three-dimensional (3-D) effects on parabolic trough optical performance. The mathematical steps of this analytical approach are presented and implemented numerically as part of the suite of FirstOPTIC code. In addition, the new code has been carefully validated against ray-tracing simulation results and available numerical solutions. This new analytical approach to treating 3-D effects will facilitate further understanding and analysis of the optical performance of trough collectors as a function of incidence angle.
Three-dimensional model analysis and processing
Yu, Faxin; Luo, Hao; Wang, Pinghui
2011-01-01
This book focuses on five hot research directions in 3D model analysis and processing in computer science: compression, feature extraction, content-based retrieval, irreversible watermarking and reversible watermarking.
Lv, Zheng; Xu, Jinglei; Mo, Jianwei
2017-12-01
A new method based on quasi two-dimensional supersonic flow and maximum thrust theory to design a three-dimensional nozzle while considering lateral expansion and geometric constraints is presented in this paper. To generate the configuration of the three-dimensional nozzle, the inviscid flowfield is calculated through the method of characteristics, and the reference temperature method is applied to correct the boundary layer thickness. The computational fluid dynamics approach is used to obtain the aerodynamic performance of the nozzle. Results show that the initial arc radius slightly influences the axial thrust coefficient, whereas the variations in the lateral expansion contour, the length and initial expansion angle of the lower cowl significantly affect the axial thrust coefficient. The three-dimensional nozzle designed by streamline tracing technique is also investigated for comparison to verify the superiority of the new method. The proposed nozzle shows increases in the axial thrust coefficient, lift, and pitching moment of 6.86%, 203.15%, and 642.86%, respectively, at the design point, compared with the nozzle designed by streamline tracing approach. In addition, the lateral expansion accounts for 22.46% of the entire axial thrust, while it has no contribution to the lift and pitching moment in the proposed nozzle.
Shape memory polymers: three-dimensional isotropic modeling
Balogun, Olaniyi; Mo, Changki
2014-04-01
This paper presents a comprehensive three-dimensional isotropic numerical simulation for a thermo-mechanical constitutive model of shape memory polymers (SMPs). In order to predict the thermo-mechanical behavior of SMPs, a one-dimensional rheological thermo-mechanical constitutive model is adopted, translated into a three-dimensional form and a time discrete form of the three-dimensional model is then presented. Numerical simulation of this model was developed using the UMAT subroutine capabilities of the finite element software ABAQUS. Evolution of the analysis was conducted by making use of the backward difference scheme, which was applied to all quantities within the model, including the material properties. A comparison of the numerical simulation results was carried out with the available experimental data. Numerical simulation results clearly exhibit the thermo-mechanical properties of the material which include shape fixity, shape recovery, and recovery stress. Finally, a prediction for the transverse and shear directions of the material is presented.
Geometric tuning of thermal conductivity in three-dimensional anisotropic phononic crystals.
Wei, Zhiyong; Wehmeyer, Geoff; Dames, Chris; Chen, Yunfei
2016-10-07
Molecular dynamics simulations are performed to investigate the thermal transport properties of a three-dimensional (3D) anisotropic phononic crystal consisting of silicon nanowires and films. The calculation shows that the in-plane thermal conductivity is negatively correlated with the out-of-plane thermal conductivity upon making geometric changes, whether varying the nanowire diameter or the film thickness. This enables the anisotropy ratio of thermal conductivity to be tailored over a wide range, in some cases by more than a factor of 20. Similar trends in thermal conductivity are also observed from an independent phonon ray tracing simulation considering only diffuse boundary scattering effects, though the range of anisotropy ratios is smaller than that obtained in MD simulation. By analyzing the phonon dispersion relation with varied geometric parameters, it is found that increasing the nanowire diameter increases the out-of-plane acoustic phonon group velocities, but reduces the in-plane longitudinal and fast transverse acoustic phonon group velocities. The calculated phonon irradiation further verified the negative correlation between the in-plane and the out-of-plane thermal conductivity. The proposed 3D phononic crystal may find potential application in thermoelectrics, energy storage, catalysis and sensing applications owing to its widely tailorable thermal conductivity.
Two-and three-dimensional gravity modeling along western ...
Indian Academy of Sciences (India)
The western continental margin and the intraplate Narmada-Tapti rifts are primarily covered by Deccan ﬂood basalts. Three-dimensional gravity modeling of +70 mgal Bouguer gravity highs extending in the north-south direction along the western continental margin rift indicates the presence of a subsurface high density, ...
Mathematical modeling of three-dimensional images in emission tomography
International Nuclear Information System (INIS)
Koblik, Yu.N.; Khugaev, A. V.; Mktchyan, G.A.; Ioannou, P.; Dimovasili, E.
2002-01-01
The model of processing results of three-dimensional measurements in positron-emissive tomograph is proposed in this work. The algorithm of construction and visualization of phantom objects of arbitrary shape was developed and its concrete realization in view of program packet for PC was carried out
and three-dimensional gravity modeling along western continental ...
Indian Academy of Sciences (India)
Three-dimensional gravity modeling of +70 mgal Bouguer gravity highs extending in the north-south direction along the western continental margin rift indicates the presence of a subsurface high density, maﬁc-ultramaﬁc type, elongated, roughly ellipsoidal body. It is approximately 12.0 ± 1.2 km thick with its upper surface at ...
Three dimensional simulated modelling of diffusion capacitance of ...
African Journals Online (AJOL)
A three dimensional (3-D) simulated modelling was developed to analyse the excess minority carrier density in the base of a polycrystalline bifacial silicon solar cell. The concept of junction recombination velocity was ado-pted to quantify carrier flow through the junction, and to examine the solar cell diffusion capacitance for ...
Three-dimensional computer models of electrospinning systems
Directory of Open Access Journals (Sweden)
Smółka Krzysztof
2017-12-01
Full Text Available Electrospinning is a very interesting method that allows the fabrication of continuous fibers with diameters down to a few nanometers. This paper presents an overview of electrospinning systems as well as their comparison using proposed three-dimensional parameterized numerical models. The presented solutions allow an analysis of the electric field distribution.
and three-dimensional models for analysis of optical absorption
Indian Academy of Sciences (India)
Unknown
Goldberg et al 1975; Kam and Parkinson 1982; Baglio et al 1982, 1983; Oritz 1995; Li et al 1996) has been carried out on WS2, there is no detailed analysis of the absorption spectra obtained from the single crystals of WS2 on the basis of two- and three-dimensional models. We have therefore carried out this study and the.
and three-dimensional gravity modeling along western continental ...
Indian Academy of Sciences (India)
R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22
western continental margin and the intraplate Narmada-Tapti rifts suggests that the migration and concentration of high density magma in the upper lithosphere was much more dominant along the western continental margin rift. Based on the three-dimensional gravity modeling, it is conjectured that the emplacement of ...
Three dimensional rigorous model for optical scattering problems
Wei, X.
2006-01-01
We present a three-dimensional model based on the finite element method for solving the time-harmonic Maxwell equation in optics. It applies to isotropic or anisotropic dielectrics and metals, and to many configurations such as an isolated scatterer in a multilayer, bi-gratings and crystals. We
Three-dimensional computer models of electrospinning systems
Smółka, Krzysztof; Firych-Nowacka, Anna; Lefik, Marcin
2017-12-01
Electrospinning is a very interesting method that allows the fabrication of continuous fibers with diameters down to a few nanometers. This paper presents an overview of electrospinning systems as well as their comparison using proposed three-dimensional parameterized numerical models. The presented solutions allow an analysis of the electric field distribution.
International Nuclear Information System (INIS)
Yoshimatsu, Katsunori; Kawahara, Yasuhiro; Schneider, Kai; Okamoto, Naoya; Farge, Marie
2011-01-01
Scale-dependent and geometrical statistics of three-dimensional incompressible homogeneous magnetohydrodynamic turbulence without mean magnetic field are examined by means of the orthogonal wavelet decomposition. The flow is computed by direct numerical simulation with a Fourier spectral method at resolution 512 3 and a unit magnetic Prandtl number. Scale-dependent second and higher order statistics of the velocity and magnetic fields allow to quantify their intermittency in terms of spatial fluctuations of the energy spectra, the flatness, and the probability distribution functions at different scales. Different scale-dependent relative helicities, e.g., kinetic, cross, and magnetic relative helicities, yield geometrical information on alignment between the different scale-dependent fields. At each scale, the alignment between the velocity and magnetic field is found to be more pronounced than the other alignments considered here, i.e., the scale-dependent alignment between the velocity and vorticity, the scale-dependent alignment between the magnetic field and its vector potential, and the scale-dependent alignment between the magnetic field and the current density. Finally, statistical scale-dependent analyses of both Eulerian and Lagrangian accelerations and the corresponding time-derivatives of the magnetic field are performed. It is found that the Lagrangian acceleration does not exhibit substantially stronger intermittency compared to the Eulerian acceleration, in contrast to hydrodynamic turbulence where the Lagrangian acceleration shows much stronger intermittency than the Eulerian acceleration. The Eulerian time-derivative of the magnetic field is more intermittent than the Lagrangian time-derivative of the magnetic field.
Wang, Yong-Long; Jiang, Hua; Zong, Hong-Shi
2017-08-01
In the spirit of the thin-layer quantization approach, we give the formula of the geometric influences of a particle confined to a curved surface embedded in three-dimensional Euclidean space. The geometric contributions can result from the reduced commutation relation between the acted function depending on normal variable and the normal derivative. According to the formula, we obtain the geometric potential, geometric momentum, geometric orbital angular momentum, geometric linear Rashba, and cubic Dresselhaus spin-orbit couplings. As an example, a truncated cone surface is considered. We find that the geometric orbital angular momentum can provide an azimuthal polarization for spin, and the sign of the geometric Dresselhaus spin-orbit coupling can be flipped through the inclination angle of generatrix.
A three-dimensional model of women's empowerment
Huis, Marloes A.; Hansen, Nina; Otten, Sabine; Lensink, Robert
2017-01-01
Women's empowerment is an important goal in achieving sustainable development worldwide. Offering access to microfinance services to women is one way to increase women's empowerment. However, empirical evidence provides mixed results with respect to its effectiveness. We reviewed previous research on the impact of microfinance services on different aspects of women's empowerment. We propose a Three-Dimensional Model of Women's Empowerment to integrate previous findings and to gain a deeper un...
Three-dimensional Modeling of Type Ia Supernova Explosions
Khokhlov, Alexei
2001-06-01
A deflagration explosion of a Type Ia Supernova (SNIa) is studied using three-dimensional, high-resolution, adaptive mesh refinement fluid dynamic calculations. Deflagration speed in an exploding Chandrasekhar-mass carbon-oxygen white dwarf (WD) grows exponentially, reaches approximately 30the speed of sound, and then declines due to a WD expansion. Outermost layers of the WD remain unburned. The explosion energy is comparable to that of a Type Ia supernova. The freezing of turbulent motions by expansion appears to be a crucial physical mechanism regulating the strength of a supernova explosion. In contrast to one-dimensional models, three-dimensional calculations predict the formation of Si-group elements and pockets of unburned CO in the middle and in central regions of a supernova ejecta. This, and the presence of unburned outer layer of carbon-oxygen may pose problems for SNIa spectra. Explosion sensitivity to initial conditions and its relation to a diversity of SNIa is discussed.
On a Three Dimensional Vision Based Collision Avoidance Model
Parzani, Céline; Filbet, Francis
2017-08-01
This paper presents a three dimensional collision avoidance approach for aerial vehicles inspired by coordinated behaviors in biological groups. The proposed strategy aims to enable a group of vehicles to converge to a common destination point avoiding collisions with each other and with moving obstacles in their environment. The interaction rules lead the agents to adapt their velocity vectors through a modification of the relative bearing angle and the relative elevation. Moreover the model satisfies the limited field of view constraints resulting from individual perception sensitivity. From the proposed individual based model, a mean-field kinetic model is derived. Simulations are performed to show the effectiveness of the proposed model.
A Three-dimensional Topological Model of Ternary Phase Diagram
International Nuclear Information System (INIS)
Mu, Yingxue; Bao, Hong
2017-01-01
In order to obtain a visualization of the complex internal structure of ternary phase diagram, the paper realized a three-dimensional topology model of ternary phase diagram with the designed data structure and improved algorithm, under the guidance of relevant theories of computer graphics. The purpose of the model is mainly to analyze the relationship between each phase region of a ternary phase diagram. The model not only obtain isothermal section graph at any temperature, but also extract a particular phase region in which users are interested. (paper)
Three-dimensional modelling of a dc non-transferred arc plasma torch
International Nuclear Information System (INIS)
Li Heping; Chen Xi
2001-01-01
Three-dimensional (3D) modelling results are presented concerning a direct current (dc) non-transferred arc plasma torch with axisymmetrical geometrical configuration and axisymmetrical boundary conditions. It is shown that the arc is locally attached at the anode surface of the plasma torch, and the heat transfer and plasma flow within the torch are of 3D features. The predicted arc root location at the anode surface and arc voltage of the torch are very consistent with corresponding experimental results. (author)
Three-dimensional geometric analysis of the talus for designing talar prosthetics.
Islam, Kamrul; Dobbe, Ashlee; Duke, Kajsa; El-Rich, Marwan; Dhillon, Sukhvinder; Adeeb, Samer; Jomha, Nadr M
2014-04-01
Proper understanding of the complex geometric shape of the talus bone is important for the design of generic talar body prosthetics and restoration of the proper ankle joint function after surgery. To date, all talus implants have been patient-specific with the limitation that complex computer modeling is required to produce a mirrored image from the unaffected opposite side followed by machining a patient-specific prosthesis. To develop an "off-the-shelf" non-custom talar prosthesis, it is important to perform a thorough investigation of the geometric shape of the talus bone. This article addresses the applicability of a scaling approach for investigating the geometric shape and similarity of talus bones. This study used computed tomography scan images of the ankle joints of 27 different subjects to perform the analysis. Results of the deviation analyses showed that the deviation in the articulating surfaces of the talus bones was not excessive in terms of talus size. These results suggest that a proposed range of five implant sizes is possible. Finally, it is concluded that the talus bones of the ankle joints are geometrically similar, and a proposed range of five implant sizes will fit a wide range of subjects. This information may help to develop generic talus implants that might be applicable to patients with a severe talus injury.
Chern-Simons as a geometrical set up for three dimensional gauge theories
International Nuclear Information System (INIS)
Lemes, V.E.R; Jesus, C. Linhares de; Sorella, S.P.; Villar, L.C.Q.; Ventura, O.S.
1997-12-01
Three dimensional Yang-Mills gauge theories in the presence of the Chern-Simons action are seen as being generated by the pure topological Chern-Simons term through nonlinear covariant redefinitions of the gauge field. (author)
Magnetic properties of three-dimensional Hubbard-sigma model
International Nuclear Information System (INIS)
Yamamoto, Hisashi; Ichinose, Ikuo; Tatara, Gen; Matsui, Tetsuo.
1989-11-01
It is broadly viewed that the magnetism may play an important role in the high-T c superconductivity in the lamellar CuO 2 materials. In this paper, based on a Hubbard-inspired CP 1 or S 2 nonlinear σ model, we give a quantitative study of some magnetic properties in and around the Neel ordered state of three-dimensional quantum antiferromagnets such as La 2 CuO 4 with and without small hole doping. Our model is a (3+1) dimensional effective field theory describing the low energy spin dynamics of a three-dimensional Hubbard model with a very weak interlayer coupling. The effect of hole dynamics is taken into account in the leading approximation by substituting the CP 1 coupling with an 'effective' one determined by the concentration and the one-loop correction of hole fermions. A stationary-phase equation for the one-loop effective potential of S 2 model is analyzed numerically. The behavior of Neel temperature, magnetization (long range Neel order), spin correlation length, etc as functions of anisotropic parameter, temperature, hole concentrations, etc are investigated in detail. A phase diagram is also supported by the renormlization group analysis. The results show that our anisotropic field theory model with certain values of parameters could give a reasonably well description of the magnetic properties indicated by some experiments on pure and doped La 2 CuO 4 . (author)
Three dimensional mathematical model of tooth for finite element analysis
Directory of Open Access Journals (Sweden)
Puškar Tatjana
2010-01-01
Full Text Available Introduction. The mathematical model of the abutment tooth is the starting point of the finite element analysis of stress and deformation of dental structures. The simplest and easiest way is to form a model according to the literature data of dimensions and morphological characteristics of teeth. Our method is based on forming 3D models using standard geometrical forms (objects in programmes for solid modeling. Objective. Forming the mathematical model of abutment of the second upper premolar for finite element analysis of stress and deformation of dental structures. Methods. The abutment tooth has a form of a complex geometric object. It is suitable for modeling in programs for solid modeling SolidWorks. After analyzing the literature data about the morphological characteristics of teeth, we started the modeling dividing the tooth (complex geometric body into simple geometric bodies (cylinder, cone, pyramid,.... Connecting simple geometric bodies together or substricting bodies from the basic body, we formed complex geometric body, tooth. The model is then transferred into Abaqus, a computational programme for finite element analysis. Transferring the data was done by standard file format for transferring 3D models ACIS SAT. Results. Using the programme for solid modeling SolidWorks, we developed three models of abutment of the second maxillary premolar: the model of the intact abutment, the model of the endodontically treated tooth with two remaining cavity walls and the model of the endodontically treated tooth with two remaining walls and inserted post. Conclusion Mathematical models of the abutment made according to the literature data are very similar with the real abutment and the simplifications are minimal. These models enable calculations of stress and deformation of the dental structures. The finite element analysis provides useful information in understanding biomechanical problems and gives guidance for clinical research.
[Three dimensional mathematical model of tooth for finite element analysis].
Puskar, Tatjana; Vasiljević, Darko; Marković, Dubravka; Jevremović, Danimir; Pantelić, Dejan; Savić-Sević, Svetlana; Murić, Branka
2010-01-01
The mathematical model of the abutment tooth is the starting point of the finite element analysis of stress and deformation of dental structures. The simplest and easiest way is to form a model according to the literature data of dimensions and morphological characteristics of teeth. Our method is based on forming 3D models using standard geometrical forms (objects) in programmes for solid modeling. Forming the mathematical model of abutment of the second upper premolar for finite element analysis of stress and deformation of dental structures. The abutment tooth has a form of a complex geometric object. It is suitable for modeling in programs for solid modeling SolidWorks. After analysing the literature data about the morphological characteristics of teeth, we started the modeling dividing the tooth (complex geometric body) into simple geometric bodies (cylinder, cone, pyramid,...). Connecting simple geometric bodies together or substricting bodies from the basic body, we formed complex geometric body, tooth. The model is then transferred into Abaqus, a computational programme for finite element analysis. Transferring the data was done by standard file format for transferring 3D models ACIS SAT. Using the programme for solid modeling SolidWorks, we developed three models of abutment of the second maxillary premolar: the model of the intact abutment, the model of the endodontically treated tooth with two remaining cavity walls and the model of the endodontically treated tooth with two remaining walls and inserted post. Mathematical models of the abutment made according to the literature data are very similar with the real abutment and the simplifications are minimal. These models enable calculations of stress and deformation of the dental structures. The finite element analysis provides useful information in understanding biomechanical problems and gives guidance for clinical research.
Comparison of one-, two-, and three-dimensional models for mass transport of radionuclides
International Nuclear Information System (INIS)
Prickett, T.A.; Voorhees, M.L.; Herzog, B.L.
1980-02-01
This technical memorandum compares one-, two-, and three-dimensional models for studying regional mass transport of radionuclides in groundwater associated with deep repository disposal of high-level radioactive wastes. In addition, this report outlines the general conditions for which a one- or two-dimensional model could be used as an alternate to a three-dimensional model analysis. The investigation includes a review of analytical and numerical models in addition to consideration of such conditions as rock and fluid heterogeneity, anisotropy, boundary and initial conditions, and various geometric shapes of repository sources and sinks. Based upon current hydrologic practice, each review is taken separately and discussed to the extent that the researcher can match his problem conditions with the minimum number of model dimensions necessary for an accurate solution
Modeling emissions for three-dimensional atmospheric chemistry transport models.
Matthias, Volker; Arndt, Jan A; Aulinger, Armin; Bieser, Johannes; Denier Van Der Gon, Hugo; Kranenburg, Richard; Kuenen, Jeroen; Neumann, Daniel; Pouliot, George; Quante, Markus
2018-01-24
Poor air quality is still a threat for human health in many parts of the world. In order to assess measures for emission reductions and improved air quality, three-dimensional atmospheric chemistry transport modeling systems are used in numerous research institutions and public authorities. These models need accurate emission data in appropriate spatial and temporal resolution as input. This paper reviews the most widely used emission inventories on global and regional scale and looks into the methods used to make the inventory data model ready. Shortcomings of using standard temporal profiles for each emission sector are discussed and new methods to improve the spatio-temporal distribution of the emissions are presented. These methods are often neither top-down nor bottom-up approaches but can be seen as hybrid methods that use detailed information about the emission process to derive spatially varying temporal emission profiles. These profiles are subsequently used to distribute bulk emissions like national totals on appropriate grids. The wide area of natural emissions is also summarized and the calculation methods are described. Almost all types of natural emissions depend on meteorological information, which is why they are highly variable in time and space and frequently calculated within the chemistry transport models themselves. The paper closes with an outlook for new ways to improve model ready emission data, for example by using external databases about road traffic flow or satellite data to determine actual land use or leaf area. In a world where emission patterns change rapidly, it seems appropriate to use new types of statistical and observational data to create detailed emission data sets and keep emission inventories up-to-date. Emission data is probably the most important input for chemistry transport model (CTM) systems. It needs to be provided in high temporal and spatial resolution and on a grid that is in agreement with the CTM grid. Simple
A three-dimensional radiative transfer model for shallow water environments.
Hedley, John
2008-12-22
A geometric optical model for three-dimensional radiative transfer capable of handling arbitrary arrangements of surfaces within anisotropic scattering media is described. The model operates by discretizing surfaces and volumes into patches and voxels and establishing the radiative transfer relationship between every pair of elements. In a plane-parallel configuration results for directional radiance agree closely with the numerical integration invariant imbedded method. Model accuracy for two examples incorporating surface water waves and complex benthic structures were assessed by conservation of energy, errors were less than 1%. Potential applications in remote sensing or photobiological studies of structurally complex benthos in shallow water environments are illustrated.
A THREE-DIMENSIONAL BABCOCK-LEIGHTON SOLAR DYNAMO MODEL
International Nuclear Information System (INIS)
Miesch, Mark S.; Dikpati, Mausumi
2014-01-01
We present a three-dimensional (3D) kinematic solar dynamo model in which poloidal field is generated by the emergence and dispersal of tilted sunspot pairs (more generally bipolar magnetic regions, or BMRs). The axisymmetric component of this model functions similarly to previous 2.5 dimensional (2.5D, axisymmetric) Babcock-Leighton (BL) dynamo models that employ a double-ring prescription for poloidal field generation but we generalize this prescription into a 3D flux emergence algorithm that places BMRs on the surface in response to the dynamo-generated toroidal field. In this way, the model can be regarded as a unification of BL dynamo models (2.5D in radius/latitude) and surface flux transport models (2.5D in latitude/longitude) into a more self-consistent framework that builds on the successes of each while capturing the full 3D structure of the evolving magnetic field. The model reproduces some basic features of the solar cycle including an 11 yr periodicity, equatorward migration of toroidal flux in the deep convection zone, and poleward propagation of poloidal flux at the surface. The poleward-propagating surface flux originates as trailing flux in BMRs, migrates poleward in multiple non-axisymmetric streams (made axisymmetric by differential rotation and turbulent diffusion), and eventually reverses the polar field, thus sustaining the dynamo. In this Letter we briefly describe the model, initial results, and future plans
Three-dimensional decomposition models for carbon productivity
International Nuclear Information System (INIS)
Meng, Ming; Niu, Dongxiao
2012-01-01
This paper presents decomposition models for the change in carbon productivity, which is considered a key indicator that reflects the contributions to the control of greenhouse gases. Carbon productivity differential was used to indicate the beginning of decomposition. After integrating the differential equation and designing the Log Mean Divisia Index equations, a three-dimensional absolute decomposition model for carbon productivity was derived. Using this model, the absolute change of carbon productivity was decomposed into a summation of the absolute quantitative influences of each industrial sector, for each influence factor (technological innovation and industrial structure adjustment) in each year. Furthermore, the relative decomposition model was built using a similar process. Finally, these models were applied to demonstrate the decomposition process in China. The decomposition results reveal several important conclusions: (a) technological innovation plays a far more important role than industrial structure adjustment; (b) industry and export trade exhibit great influence; (c) assigning the responsibility for CO 2 emission control to local governments, optimizing the structure of exports, and eliminating backward industrial capacity are highly essential to further increase China's carbon productivity. -- Highlights: ► Using the change of carbon productivity to measure a country's contribution. ► Absolute and relative decomposition models for carbon productivity are built. ► The change is decomposed to the quantitative influence of three-dimension. ► Decomposition results can be used for improving a country's carbon productivity.
Development of an interactive anatomical three-dimensional eye model.
Allen, Lauren K; Bhattacharyya, Siddhartha; Wilson, Timothy D
2015-01-01
The discrete anatomy of the eye's intricate oculomotor system is conceptually difficult for novice students to grasp. This is problematic given that this group of muscles represents one of the most common sites of clinical intervention in the treatment of ocular motility disorders and other eye disorders. This project was designed to develop a digital, interactive, three-dimensional (3D) model of the muscles and cranial nerves of the oculomotor system. Development of the 3D model utilized data from the Visible Human Project (VHP) dataset that was refined using multiple forms of 3D software. The model was then paired with a virtual user interface in order to create a novel 3D learning tool for the human oculomotor system. Development of the virtual eye model was done while attempting to adhere to the principles of cognitive load theory (CLT) and the reduction of extraneous load in particular. The detailed approach, digital tools employed, and the CLT guidelines are described herein. © 2014 American Association of Anatomists.
A comprehensive three-dimensional model of the cochlea
International Nuclear Information System (INIS)
Givelberg, Edward; Bunn, Julian
2003-01-01
The human cochlea is a remarkable device, able to discern extremely small amplitude sound pressure waves, and discriminate between very close frequencies. Simulation of the cochlea is computationally challenging due to its complex geometry, intricate construction and small physical size. We have developed, and are continuing to refine, a detailed three-dimensional computational model based on an accurate cochlear geometry obtained from physical measurements. In the model, the immersed boundary method is used to calculate the fluid-structure interactions produced in response to incoming sound waves. The model includes a detailed and realistic description of the various elastic structures present. In this paper, we describe the computational model and its performance on the latest generation of shared memory servers from Hewlett Packard. Using compiler generated threads and OpenMP directives, we have achieved a high degree of parallelism in the executable, which has made possible several large scale numerical simulation experiments that study the interesting features of the cochlear system. We show several results from these simulations, reproducing some of the basic known characteristics of cochlear mechanics
Three-dimensional transient electromagnetic modeling in the Laplace Domain
International Nuclear Information System (INIS)
Mizunaga, H.; Lee, Ki Ha; Kim, H.J.
1998-01-01
In modeling electromagnetic responses, Maxwell's equations in the frequency domain are popular and have been widely used (Nabighian, 1994; Newman and Alumbaugh, 1995; Smith, 1996, to list a few). Recently, electromagnetic modeling in the time domain using the finite difference (FDTD) method (Wang and Hohmann, 1993) has also been used to study transient electromagnetic interactions in the conductive medium. This paper presents a new technique to compute the electromagnetic response of three-dimensional (3-D) structures. The proposed new method is based on transforming Maxwell's equations to the Laplace domain. For each discrete Laplace variable, Maxwell's equations are discretized in 3-D using the staggered grid and the finite difference method (FDM). The resulting system of equations is then solved for the fields using the incomplete Cholesky conjugate gradient (ICCG) method. The new method is particularly effective in saving computer memory since all the operations are carried out in real numbers. For the same reason, the computing speed is faster than frequency domain modeling. The proposed approach can be an extremely useful tool in developing an inversion algorithm using the time domain data
Three-Dimensional Flow Separation Induced by a Model Vocal Fold Polyp
Stewart, Kelley C.; Erath, Byron D.; Plesniak, Michael W.
2012-11-01
The fluid-structure energy exchange process for normal speech has been studied extensively, but it is not well understood for pathological conditions. Polyps and nodules, which are geometric abnormalities that form on the medial surface of the vocal folds, can disrupt vocal fold dynamics and thus can have devastating consequences on a patient's ability to communicate. A recent in-vitro investigation of a model polyp in a driven vocal fold apparatus demonstrated that such a geometric abnormality considerably disrupts the glottal jet behavior and that this flow field adjustment was a likely reason for the severe degradation of the vocal quality in patients. Understanding of the formation and propagation of vortical structures from a geometric protuberance, and their subsequent impact on the aerodynamic loadings that drive vocal fold dynamic, is a critical component in advancing the treatment of this pathological condition. The present investigation concerns the three-dimensional flow separation induced by a wall-mounted prolate hemispheroid with a 2:1 aspect ratio in cross flow, i.e. a model vocal fold polyp. Unsteady three-dimensional flow separation and its impact of the wall pressure loading are examined using skin friction line visualization and wall pressure measurements. Supported by the National Science Foundation, Grant No. CBET-1236351 and GW Center for Biomimetics and Bioinspired Engineering (COBRE).
ALGE3D: A Three-Dimensional Transport Model
Maze, G. M.
2017-12-01
Of the top 10 most populated US cities from a 2015 US Census Bureau estimate, 7 of the cities are situated near the ocean, a bay, or on one of the Great Lakes. A contamination of the water ways in the United States could be devastating to the economy (through tourism and industries such as fishing), public health (from direct contact, or contaminated drinking water), and in some cases even infrastructure (water treatment plants). Current national response models employed by emergency response agencies have well developed models to simulate the effects of hazardous contaminants in riverine systems that are primarily driven by one-dimensional flows; however in more complex systems, such as tidal estuaries, bays, or lakes, a more complex model is needed. While many models exist, none are capable of quick deployment in emergency situations that could contain a variety of release situations including a mixture of both particulate and dissolved chemicals in a complex flow area. ALGE3D, developed at the Department of Energy's (DOE) Savannah River National Laboratory (SRNL), is a three-dimensional hydrodynamic code which solves the momentum, mass, and energy conservation equations to predict the movement and dissipation of thermal or dissolved chemical plumes discharged into cooling lakes, rivers, and estuaries. ALGE3D is capable of modeling very complex flows, including areas with tidal flows which include wetting and drying of land. Recent upgrades have increased the capabilities including the transport of particulate tracers, allowing for more complete modeling of the transport of pollutants. In addition the model is capable of coupling with a one-dimension riverine transport model or a two-dimension atmospheric deposition model in the event that a contamination event occurs upstream or upwind of the water body.
A three dimensional model of a vane rheometer
International Nuclear Information System (INIS)
Nazari, Behzad; Moghaddam, Ramin Heidari; Bousfield, Douglas
2013-01-01
Highlights: • FEM was used to calculate the isothermal flow parameters in a vane geometry. • Velocity, pressure and then stress fields were obtained. • Using total stress, shaft torque was calculated to compare with experimental data. • A modified cell Reynolds number and power number were used to study flow pattern. • A comparison between 2D and 3D modeling was done based on calculated torques. -- Abstract: Vane type geometries are often used in rheometers to avoid slippage between the sample and the fixtures. While yield stress and other rheological properties can be obtained with this geometry, a complete analysis of this complex flow field is lacking in the literature. In this work, a finite element method is used to calculate the isothermal flow parameters in a vane geometry. The method solves the mass and momentum continuity equations to obtain velocity, pressure and then stress fields. Using the total stress numerical data, we calculated the torque applied on solid surfaces. The validity of the computational model was established by comparing the results to experimental results of shaft torque at different angular velocities. The conditions where inertial terms become important and the linear relationship between torque and stress are quantified with dimensionless groups. The accuracy of a two dimensional analysis is compared to the three dimensional results
Three dimensional modelling of earthquake rupture cycles on frictional faults
Simpson, Guy; May, Dave
2017-04-01
We are developing an efficient MPI-parallel numerical method to simulate earthquake sequences on preexisting faults embedding within a three dimensional viscoelastic half-space. We solve the velocity form of the elasto(visco)dynamic equations using a continuous Galerkin Finite Element Method on an unstructured pentahedral mesh, which thus permits local spatial refinement in the vicinity of the fault. Friction sliding is coupled to the viscoelastic solid via rate- and state-dependent friction laws using the split-node technique. Our coupled formulation employs a picard-type non-linear solver with a fully implicit, first order accurate time integrator that utilises an adaptive time step that efficiently evolves the system through multiple seismic cycles. The implementation leverages advanced parallel solvers, preconditioners and linear algebra from the Portable Extensible Toolkit for Scientific Computing (PETSc) library. The model can treat heterogeneous frictional properties and stress states on the fault and surrounding solid as well as non-planar fault geometries. Preliminary tests show that the model successfully reproduces dynamic rupture on a vertical strike-slip fault in a half-space governed by rate-state friction with the ageing law.
Modeling Three-Dimensional Chromosome Structures Using Gene Expression Data.
Xiao, Guanghua; Wang, Xinlei; Khodursky, Arkady B
2011-03-01
Recent genomic studies have shown that significant chromosomal spatial correlation exists in gene expression of many organisms. Interestingly, coexpression has been observed among genes separated by a fixed interval in specific regions of a chromosome chain, which is likely caused by three-dimensional (3D) chromosome folding structures. Modeling such spatial correlation explicitly may lead to essential understandings of 3D chromosome structures and their roles in transcriptional regulation. In this paper, we explore chromosomal spatial correlation induced by 3D chromosome structures, and propose a hierarchical Bayesian method based on helical structures to formally model and incorporate the correlation into the analysis of gene expression microarray data. It is the first study to quantify and infer 3D chromosome structures in vivo using expression microarrays. Simulation studies show computing feasibility of the proposed method and that, under the assumption of helical chromosome structures, it can lead to precise estimation of structural parameters and gene expression levels. Real data applications demonstrate an intriguing biological phenomenon that functionally associated genes, which are far apart along the chromosome chain, are brought into physical proximity by chromosomal folding in 3D space to facilitate their coexpression. It leads to important biological insight into relationship between chromosome structure and function.
Three-Dimensional Modeling of Fracture Clusters in Geothermal Reservoirs
Energy Technology Data Exchange (ETDEWEB)
Ghassemi, Ahmad [Univ. of Oklahoma, Norman, OK (United States)
2017-08-11
The objective of this is to develop a 3-D numerical model for simulating mode I, II, and III (tensile, shear, and out-of-plane) propagation of multiple fractures and fracture clusters to accurately predict geothermal reservoir stimulation using the virtual multi-dimensional internal bond (VMIB). Effective development of enhanced geothermal systems can significantly benefit from improved modeling of hydraulic fracturing. In geothermal reservoirs, where the temperature can reach or exceed 350oC, thermal and poro-mechanical processes play an important role in fracture initiation and propagation. In this project hydraulic fracturing of hot subsurface rock mass will be numerically modeled by extending the virtual multiple internal bond theory and implementing it in a finite element code, WARP3D, a three-dimensional finite element code for solid mechanics. The new constitutive model along with the poro-thermoelastic computational algorithms will allow modeling the initiation and propagation of clusters of fractures, and extension of pre-existing fractures. The work will enable the industry to realistically model stimulation of geothermal reservoirs. The project addresses the Geothermal Technologies Office objective of accurately predicting geothermal reservoir stimulation (GTO technology priority item). The project goal will be attained by: (i) development of the VMIB method for application to 3D analysis of fracture clusters; (ii) development of poro- and thermoelastic material sub-routines for use in 3D finite element code WARP3D; (iii) implementation of VMIB and the new material routines in WARP3D to enable simulation of clusters of fractures while accounting for the effects of the pore pressure, thermal stress and inelastic deformation; (iv) simulation of 3D fracture propagation and coalescence and formation of clusters, and comparison with laboratory compression tests; and (v) application of the model to interpretation of injection experiments (planned by our
A Three-Dimensional Model of the Yeast Genome
Noble, William; Duan, Zhi-Jun; Andronescu, Mirela; Schutz, Kevin; McIlwain, Sean; Kim, Yoo Jung; Lee, Choli; Shendure, Jay; Fields, Stanley; Blau, C. Anthony
Layered on top of information conveyed by DNA sequence and chromatin are higher order structures that encompass portions of chromosomes, entire chromosomes, and even whole genomes. Interphase chromosomes are not positioned randomly within the nucleus, but instead adopt preferred conformations. Disparate DNA elements co-localize into functionally defined aggregates or factories for transcription and DNA replication. In budding yeast, Drosophila and many other eukaryotes, chromosomes adopt a Rabl configuration, with arms extending from centromeres adjacent to the spindle pole body to telomeres that abut the nuclear envelope. Nonetheless, the topologies and spatial relationships of chromosomes remain poorly understood. Here we developed a method to globally capture intra- and inter-chromosomal interactions, and applied it to generate a map at kilobase resolution of the haploid genome of Saccharomyces cerevisiae. The map recapitulates known features of genome organization, thereby validating the method, and identifies new features. Extensive regional and higher order folding of individual chromosomes is observed. Chromosome XII exhibits a striking conformation that implicates the nucleolus as a formidable barrier to interaction between DNA sequences at either end. Inter-chromosomal contacts are anchored by centromeres and include interactions among transfer RNA genes, among origins of early DNA replication and among sites where chromosomal breakpoints occur. Finally, we constructed a three-dimensional model of the yeast genome. Our findings provide a glimpse of the interface between the form and function of a eukaryotic genome.
Mano, Tomohiro; Ohtsuki, Tomi
2017-11-01
The three-dimensional Anderson model is a well-studied model of disordered electron systems that shows the delocalization-localization transition. As in our previous papers on two- and three-dimensional (2D, 3D) quantum phase transitions [https://doi.org/10.7566/JPSJ.85.123706" xlink:type="simple">J. Phys. Soc. Jpn. 85, 123706 (2016), https://doi.org/10.7566/JPSJ.86.044708" xlink:type="simple">86, 044708 (2017)], we used an image recognition algorithm based on a multilayered convolutional neural network. However, in contrast to previous papers in which 2D image recognition was used, we applied 3D image recognition to analyze entire 3D wave functions. We show that a full phase diagram of the disorder-energy plane is obtained once the 3D convolutional neural network has been trained at the band center. We further demonstrate that the full phase diagram for 3D quantum bond and site percolations can be drawn by training the 3D Anderson model at the band center.
Making three-dimensional Monson's sphere using virtual dental models.
Nam, Shin-Eun; Park, Young-Seok; Lee, WooCheol; Ahn, Sug-Joon; Lee, Seung-Pyo
2013-04-01
The Monson's sphere and curve of Wilson can be used as reference for prosthetic reconstructions or orthodontic treatments. This study aimed to generate and measure the three-dimensional (3-D) Monson's sphere and curve of Wilson using virtual dental models and custom software. Mandibular dental casts from 79 young adults of Korean descent were scanned and rendered as virtual dental models using a 3-D digitizing scanner. 26 landmarks were digitized on the virtual dental models using a custom made software program. The Monson's sphere was estimated by fitting a sphere to the cusp tips using a least-squares method. Two curves of Wilson were generated by finding the intersecting circle between the Monson's sphere and two vertical planes orthogonal to a virtual occlusal plane. Non-parametric Mann-Whitney and Kruskal-Wallis tests were performed to test for difference between sex and in cusp number within tooth position. The mean radius of Monson's sphere was 110.89 ± 25.75 mm. There were significant differences between males and females in all measurements taken (pocclusal curvature (p>0.05). This study describes a best-fit algorithm for generating 3-D Monson's sphere using occlusal curves quantified from virtual dental models. The radius of Monson's sphere in Korean subjects was greater than the original four-inch value suggested by Monson. The Monson's sphere and curve of Wilson can be used as a reference for prosthetic reconstruction and orthodontic treatment. The data found in this study may be applied to improve dental treatment results. Copyright © 2013 Elsevier Ltd. All rights reserved.
Construction and validation of a three-dimensional finite element model of degenerative scoliosis.
Zheng, Jie; Yang, Yonghong; Lou, Shuliang; Zhang, Dongsheng; Liao, Shenghui
2015-12-24
With the aging of the population, degenerative scoliosis (DS) incidence rate is increasing. In recent years, increasing research on this topic has been carried out, yet biomechanical research on the subject is seldom seen and in vitro biomechanical model of DS nearly cannot be available. The objective of this study was to develop and validate a complete three-dimensional finite element model of DS in order to build the digital platform for further biomechanical study. A 55-year-old female DS patient (Suer Pan, ID number was P141986) was selected for this study. This study was performed in accordance with the ethical standards of Declaration of Helsinki and its amendments and was approved by the local ethics committee (117 hospital of PLA ethics committee). Spiral computed tomography (CT) scanning was conducted on the patient's lumbar spine from the T12 to S1. CT images were then imported into a finite element modeling system. A three-dimensional solid model was then formed from segmentation of the CT scan. The three-dimensional model of each vertebra was then meshed, and material properties were assigned to each element according to the pathological characteristics of DS. Loads and boundary conditions were then applied in such a manner as to simulate in vitro biomechanical experiments conducted on lumbar segments. The results of the model were then compared with experimental results in order to validate the model. An integral three-dimensional finite element model of DS was built successfully, consisting of 113,682 solid elements, 686 cable elements, 33,329 shell elements, 4968 target elements, 4968 contact elements, totaling 157,635 elements, and 197,374 nodes. The model accurately described the physical features of DS and was geometrically similar to the object of study. The results of analysis with the finite element model agreed closely with in vitro experiments, validating the accuracy of the model. The three-dimensional finite element model of DS built in
Three-Dimensional Analysis and Modeling of a Wankel Engine
Raju, M. S.; Willis, E. A.
1991-01-01
A new computer code, AGNI-3D, has been developed for the modeling of combustion, spray, and flow properties in a stratified-charge rotary engine (SCRE). The mathematical and numerical details of the new code are described by the first author in a separate NASA publication. The solution procedure is based on an Eulerian-Lagrangian approach where the unsteady, three-dimensional Navier-Stokes equations for a perfect gas-mixture with variable properties are solved in generalized, Eulerian coordinates on a moving grid by making use of an implicit finite-volume, Steger-Warming flux vector splitting scheme. The liquid-phase equations are solved in Lagrangian coordinates. The engine configuration studied was similar to existing rotary engine flow-visualization and hot-firing test rigs. The results of limited test cases indicate a good degree of qualitative agreement between the predicted and measured pressures. It is conjectured that the impulsive nature of the torque generated by the observed pressure nonuniformity may be one of the mechanisms responsible for the excessive wear of the timing gears observed during the early stages of the rotary combustion engine (RCE) development. It was identified that the turbulence intensities near top-dead-center were dominated by the compression process and only slightly influenced by the intake and exhaust processes. Slow mixing resulting from small turbulence intensities within the rotor pocket and also from a lack of formation of any significant recirculation regions within the rotor pocket were identified as the major factors leading to incomplete combustion. Detailed flowfield results during exhaust and intake, fuel injection, fuel vaporization, combustion, mixing and expansion processes are also presented. The numerical procedure is very efficient as it takes 7 to 10 CPU hours on a CRAY Y-MP for one entire engine cycle when the computations are performed over a 31 x16 x 20 grid.
Imai, Takashi; Kovalenko, Andriy; Hirata, Fumio
2005-04-14
The three-dimensional reference interaction site model (3D-RISM) theory is applied to the analysis of hydration effects on the partial molar volume of proteins. For the native structure of some proteins, the partial molar volume is decomposed into geometric and hydration contributions using the 3D-RISM theory combined with the geometric volume calculation. The hydration contributions are correlated with the surface properties of the protein. The thermal volume, which is the volume of voids around the protein induced by the thermal fluctuation of water molecules, is directly proportional to the accessible surface area of the protein. The interaction volume, which is the contribution of electrostatic interactions between the protein and water molecules, is apparently governed by the charged atomic groups on the protein surface. The polar atomic groups do not make any contribution to the interaction volume. The volume differences between low- and high-pressure structures of lysozyme are also analyzed by the present method.
Modelling flexible link manipulators in the three-dimensional space
Kozel, David
The force/torque relationship between the joints and the end effector of flexible link manipulators is affected not only by the motion of the joints but also by translations and rotations of the links due to their bending and torsion effects. These inaccuracies in the force/torque relationship for flexible manipulators in the three-dimensional space are addressed. This thesis presents the development of a systematic technique for determining for force/torque relationship between the joints and the end effector for flexible link manipulators. The proposed technique accounts for link bending and torsion in the kinematic equations of a flexible manipulator while considering rigid hubs and tools attached to the ends of the links. A procedure for modelling link bending and torsion to within a desired accuracy has also been developed. The resulting model is independent of manipulator configuration. In this technique, vector cross products are used instead of partial derivatives. This reduces inaccuracies which result from approximations made in the kinematic equations when modelling bending and torsion of the links. The magnitude and location of these inaccuracies are characterized. The validity of the proposed technique/procedure and the inaccuracies noted are demonstrated for link bending of a single-link planar manipulator by comparing simulations of the resulting force/torque relationships to results obtained experimentally; however, the experiments were not able to illustrate the torsion effect in the proposed model. Results indicate that the magnitude and location of the errors in the force/torque relationship are dependent upon the rotation due to link deformation, the 'length' of the rest of the manipulator, and the configuration of the manipulator. Although the proposed technique is able to account for the link bending and torsion effects in the kinematic equations of a flexible manipulator, it also suffers from several limitations. These include: translations
Three dimensional heat transport modeling in Vossoroca reservoir
Arcie Polli, Bruna; Yoshioka Bernardo, Julio Werner; Hilgert, Stephan; Bleninger, Tobias
2017-04-01
Freshwater reservoirs are used for many purposes as hydropower generation, water supply and irrigation. In Brazil, according to the National Energy Balance of 2013, hydropower energy corresponds to 70.1% of the Brazilian demand. Superficial waters (which include rivers, lakes and reservoirs) are the most used source for drinking water supply - 56% of the municipalities use superficial waters as a source of water. The last two years have shown that the Brazilian water and electricity supply is highly vulnerable and that improved management is urgently needed. The construction of reservoirs affects physical, chemical and biological characteristics of the water body, e.g. stratification, temperature, residence time and turbulence reduction. Some water quality issues related to reservoirs are eutrophication, greenhouse gas emission to the atmosphere and dissolved oxygen depletion in the hypolimnion. The understanding of the physical processes in the water body is fundamental to reservoir management. Lakes and reservoirs may present a seasonal behavior and stratify due to hydrological and meteorological conditions, and especially its vertical distribution may be related to water quality. Stratification can control heat and dissolved substances transport. It has been also reported the importance of horizontal temperature gradients, e.g. inflows and its density and processes of mass transfer from shallow to deeper regions of the reservoir, that also may impact water quality. Three dimensional modeling of the heat transport in lakes and reservoirs is an important tool to the understanding and management of these systems. It is possible to estimate periods of large vertical temperature gradients, inhibiting vertical transport and horizontal gradients, which could be responsible for horizontal transport of heat and substances (e.g. differential cooling or inflows). Vossoroca reservoir was constructed in 1949 by the impoundment of São João River and is located near to
FRiED: A Novel Three-dimensional Model of Coronal Mass Ejections
Isavnin, A.
2016-12-01
We present a novel three-dimensional (3D) model of coronal mass ejections (CMEs) that unifies all key evolutionary aspects of CMEs and encapsulates their 3D magnetic field configuration. This fully analytic model is capable of reproducing the global geometrical shape of a CME with all major deformations taken into account, I.e., deflection, rotation, expansion, “pancaking,” front flattening, and rotational skew. Encapsulation of 3D magnetic structure allows the model to reproduce in-situ measurements of magnetic field for trajectories of spacecraft-CME encounters of any degree of complexity. As such, the model can be used single-handedly for the consistent analysis of both remote and in-situ observations of CMEs at any heliocentric distance. We demonstrate the latter by successfully applying the model for the analysis of two CMEs.
A three-dimensional model for T-shaped acoustic resonators with sound absorption materials.
Yu, Ganghua; Cheng, Li; Li, Deyu
2011-05-01
Recent development in noise control using T-shaped acoustic resonators calls for the development of more reliable and accurate models to predict their acoustic characteristics, which is unfortunately lacking in the literature. This paper attempts to establish such a model based on three-dimensional theory for T-shaped acoustic resonators containing sound absorption materials. The model is validated by experiments using various configurations. Predictions on fundamental and high-order resonance frequencies are compared with those obtained from the one-dimensional model and finite element analyses, and the effects of the physical and geometric parameters of the absorption materials on the resonance frequencies and Q-factor are also investigated numerically and experimentally. Limitations and applicability of existing one-dimensional models are assessed. The proposed general three-dimensional model proved to be able to provide an accurate and reliable prediction on the resonance frequencies for T-shaped acoustic resonators with or without absorption materials. This can eventually meet the requirement for resonator array design in terms of accuracy.
Mahmood, Feroze; Karthik, Swaminathan; Subramaniam, Balachundhar; Panzica, Peter J; Mitchell, John; Lerner, Adam B; Jervis, Karinne; Maslow, Andrew D
2008-04-01
To study the feasibility of using 3-dimensional (3D) echocardiography in the operating room for mitral valve repair or replacement surgery. To perform geometric analysis of the mitral valve before and after repair. Prospective observational study. Academic, tertiary care hospital. Consecutive patients scheduled for mitral valve surgery. Intraoperative reconstruction of 3D images of the mitral valve. One hundred and two patients had 3D analysis of their mitral valve. Successful image reconstruction was performed in 93 patients-8 patients had arrhythmias or a dilated mitral valve annulus resulting in significant artifacts. Time from acquisition to reconstruction and analysis was less than 5 minutes. Surgeon identification of mitral valve anatomy was 100% accurate. The study confirms the feasibility of performing intraoperative 3D reconstruction of the mitral valve. This data can be used for confirmation and communication of 2-dimensional data to the surgeons by obtaining a surgical view of the mitral valve. The incorporation of color-flow Doppler into these 3D images helps in identification of the commissural or perivalvular location of regurgitant orifice. With improvements in the processing power of the current generation of echocardiography equipment, it is possible to quickly acquire, reconstruct, and manipulate images to help with timely diagnosis and surgical planning.
Simulations of Heat Transport Phenomena in a Three-Dimensional Model of Knitted Fabric
Directory of Open Access Journals (Sweden)
Puszkarz A.K.
2016-09-01
Full Text Available The main goal of the current work is to analyse the three-dimensional approach for modelling knitted fabric structures for future analysis of physical properties and thermal phenomena. The introduced model assumes some simplification of morphology. First, fibres in knitted fabrics are described as monofilaments characterized by isotropic thermal properties. The current form of the considered knitted fabric is determined by morphological properties of the used monofilament and simplification of the stitch shape. This simplification was based on a particular technology for the knitting process that introduces both geometric parameters and physical material properties. Detailed descriptions of heat transfer phenomena can also be considered. A sensitivity analysis of the temperature field with respect to selected structural parameters was also performed.
Langer, P.; Sepahvand, K.; Guist, C.; Bär, J.; Peplow, A.; Marburg, S.
2018-03-01
The simulation model which examines the dynamic behavior of real structures needs to address the impact of uncertainty in both geometry and material parameters. This article investigates three-dimensional finite element models for structural dynamics problems with respect to both model and parameter uncertainties. The parameter uncertainties are determined via laboratory measurements on several beam-like samples. The parameters are then considered as random variables to the finite element model for exploring the uncertainty effects on the quality of the model outputs, i.e. natural frequencies. The accuracy of the output predictions from the model is compared with the experimental results. To this end, the non-contact experimental modal analysis is conducted to identify the natural frequency of the samples. The results show a good agreement compared with experimental data. Furthermore, it is demonstrated that geometrical uncertainties have more influence on the natural frequencies compared to material parameters and material uncertainties are about two times higher than geometrical uncertainties. This gives valuable insights for improving the finite element model due to various parameter ranges required in a modeling process involving uncertainty.
Zeng, Zhi-Li; Cheng, Li-Ming; Zhu, Rui; Wang, Jian-Jie; Yu, Yan
2011-08-23
To build an effective nonlinear three-dimensional finite-element (FE) model of T(11)-L(3) segments for a further biomechanical study of thoracolumbar spine. The CT (computed tomography) scan images of healthy adult T(11)-L(3) segments were imported into software Simpleware 2.0 to generate a triangular mesh model. Using software Geomagic 8 for model repair and optimization, a solid model was generated into the finite element software Abaqus 6.9. The reasonable element C3D8 was selected for bone structures. Created between bony endplates, the intervertebral disc was subdivided into nucleus pulposus and annulus fibrosus (44% nucleus, 56% annulus). The nucleus was filled with 5 layers of 8-node solid elements and annulus reinforced by 8 crisscross collagenous fiber layers. The nucleus and annulus were meshed by C3D8RH while the collagen fibers meshed by two node-truss elements. The anterior (ALL) and posterior (PLL) longitudinal ligaments, flavum (FL), supraspinous (SSL), interspinous (ISL) and intertransverse (ITL) ligaments were modeled with S4R shell elements while capsular ligament (CL) was modeled with 3-node shell element. All surrounding ligaments were represented by envelope of 1 mm uniform thickness. The discs and bone structures were modeled with hyper-elastic and elasto-plastic material laws respectively while the ligaments governed by visco-elastic material law. The nonlinear three-dimensional finite-element model of T(11)-L(3) segments was generated and its efficacy verified through validating the geometric similarity and disc load-displacement and stress distribution under the impact of violence. Using ABAQUS/ EXPLICIT 6.9 the explicit dynamic finite element solver, the impact test was simulated in vitro. In this study, a 3-dimensional, nonlinear FE model including 5 vertebrae, 4 intervertebral discs and 7 ligaments consisted of 78 887 elements and 71 939 nodes. The model had good geometric similarity under the same conditions. The results of FEM
A microfluidically perfused three dimensional human liver model.
Rennert, Knut; Steinborn, Sandra; Gröger, Marko; Ungerböck, Birgit; Jank, Anne-Marie; Ehgartner, Josef; Nietzsche, Sandor; Dinger, Julia; Kiehntopf, Michael; Funke, Harald; Peters, Frank T; Lupp, Amelie; Gärtner, Claudia; Mayr, Torsten; Bauer, Michael; Huber, Otmar; Mosig, Alexander S
2015-12-01
Within the liver, non-parenchymal cells (NPCs) are critically involved in the regulation of hepatocyte polarization and maintenance of metabolic function. We here report the establishment of a liver organoid that integrates NPCs in a vascular layer composed of endothelial cells and tissue macrophages and a hepatic layer comprising stellate cells co-cultured with hepatocytes. The three-dimensional liver organoid is embedded in a microfluidically perfused biochip that enables sufficient nutrition supply and resembles morphological aspects of the human liver sinusoid. It utilizes a suspended membrane as a cell substrate mimicking the space of Disse. Luminescence-based sensor spots were integrated into the chip to allow online measurement of cellular oxygen consumption. Application of microfluidic flow induces defined expression of ZO-1, transferrin, ASGPR-1 along with an increased expression of MRP-2 transporter protein within the liver organoids. Moreover, perfusion was accompanied by an increased hepatobiliary secretion of 5(6)-carboxy-2',7'-dichlorofluorescein and an enhanced formation of hepatocyte microvilli. From this we conclude that the perfused liver organoid shares relevant morphological and functional characteristics with the human liver and represents a new in vitro research tool to study human hepatocellular physiology at the cellular level under conditions close to the physiological situation. Copyright © 2015 Elsevier Ltd. All rights reserved.
Three-dimensional semi-idealized model for estuarine turbidity maxima in tidally dominated estuaries
Kumar, Mohit; Schuttelaars, Henk M.; Roos, Pieter C.
2017-01-01
We develop a three-dimensional idealized model that is specifically aimed at gaining insight in the physical mechanisms resulting in the formation of estuarine turbidity maxima in tidally dominated estuaries. First, the three-dimensional equations for water motion and suspended sediment
Structural dynamic modeling for rotating blades using three dimensional finite elements
Energy Technology Data Exchange (ETDEWEB)
Kee, Young Jung; Shin, Sang Joon [Seoul National University, Seoul (Korea, Republic of)
2015-04-15
A precise analysis model was developed in this paper to investigate the dynamic characteristics of rotating composite blades. An eighteen-node solid-shell finite element was used to model the blade structures. This study is focused on geometrically nonlinear problems, because the material is assumed linear elastic. Incremental total Lagrangian approach was adopted to allow estimations on arbitrarily large rotations and displacements. The equations of motion for the finite element model were derived by using Hamilton's principle, and the resulting nonlinear equilibrium equations were solved by applying Newton-Raphson method combined with load control. A modified stress-strain relation was adopted to avoid the transverse shear locking problem, and fairly reliable results were obtained with no sign of locking phenomenon. The obtained numerical results were compared to several benchmark problems, and the results show a good correlation with the experimental data and other finite element analysis results. The vibration characteristics of shell- and beam-type blades were investigated. For shell-type blades, the dynamic characteristics may be significantly influenced by blade curvature, pre-twist, and geometric nonlinearity. For beam-type blades, one-dimensional beam and three-dimensional solid models offer comparable predictions for the straight and large aspect ratio blade. As blade aspect ratio decreases, considerable differences appear in the bending and torsion modes. The tip sweep angle tends to decrease the flap bending frequencies, but the torsion frequency increases with the tip sweep angle.
Structural dynamic modeling for rotating blades using three dimensional finite elements
International Nuclear Information System (INIS)
Kee, Young Jung; Shin, Sang Joon
2015-01-01
A precise analysis model was developed in this paper to investigate the dynamic characteristics of rotating composite blades. An eighteen-node solid-shell finite element was used to model the blade structures. This study is focused on geometrically nonlinear problems, because the material is assumed linear elastic. Incremental total Lagrangian approach was adopted to allow estimations on arbitrarily large rotations and displacements. The equations of motion for the finite element model were derived by using Hamilton's principle, and the resulting nonlinear equilibrium equations were solved by applying Newton-Raphson method combined with load control. A modified stress-strain relation was adopted to avoid the transverse shear locking problem, and fairly reliable results were obtained with no sign of locking phenomenon. The obtained numerical results were compared to several benchmark problems, and the results show a good correlation with the experimental data and other finite element analysis results. The vibration characteristics of shell- and beam-type blades were investigated. For shell-type blades, the dynamic characteristics may be significantly influenced by blade curvature, pre-twist, and geometric nonlinearity. For beam-type blades, one-dimensional beam and three-dimensional solid models offer comparable predictions for the straight and large aspect ratio blade. As blade aspect ratio decreases, considerable differences appear in the bending and torsion modes. The tip sweep angle tends to decrease the flap bending frequencies, but the torsion frequency increases with the tip sweep angle.
Directory of Open Access Journals (Sweden)
Brent J. Raiteri
2016-07-01
Full Text Available Background. Muscles not only shorten during contraction to perform mechanical work, but they also bulge radially because of the isovolumetric constraint on muscle fibres. Muscle bulging may have important implications for muscle performance, however quantifying three-dimensional (3D muscle shape changes in human muscle is problematic because of difficulties with sustaining contractions for the duration of an in vivo scan. Although two-dimensional ultrasound imaging is useful for measuring local muscle deformations, assumptions must be made about global muscle shape changes, which could lead to errors in fully understanding the mechanical behaviour of muscle and its surrounding connective tissues, such as aponeurosis. Therefore, the aims of this investigation were (a to determine the intra-session reliability of a novel 3D ultrasound (3DUS imaging method for measuring in vivo human muscle and aponeurosis deformations and (b to examine how contraction intensity influences in vivo human muscle and aponeurosis strains during isometric contractions. Methods. Participants (n = 12 were seated in a reclined position with their left knee extended and ankle at 90° and performed isometric dorsiflexion contractions up to 50% of maximal voluntary contraction. 3DUS scans of the tibialis anterior (TA muscle belly were performed during the contractions and at rest to assess muscle volume, muscle length, muscle cross-sectional area, muscle thickness and width, fascicle length and pennation angle, and central aponeurosis width and length. The 3DUS scan involved synchronous B-mode ultrasound imaging and 3D motion capture of the position and orientation of the ultrasound transducer, while successive cross-sectional slices were captured by sweeping the transducer along the muscle. Results. 3DUS was shown to be highly reliable across measures of muscle volume, muscle length, fascicle length and central aponeurosis length (ICC ≥ 0.98, CV < 1%. The TA remained
Usefulness Of Three-Dimensional Printing Models for Patients with Stoma Construction
Directory of Open Access Journals (Sweden)
Tetsuro Tominaga
2016-04-01
Full Text Available The use of patient-specific organ models in three-dimensional printing systems could be helpful for the education of patients and medical students. The aim of this study was to clarify whether the use of patient-specific stoma models is helpful for patient education. From January 2014 to September 2014, 5 patients who underwent colorectal surgery and for whom a temporary or permanent stoma had been created were involved in this study. Three-dimensional stoma models and three-dimensional face plates were created. The patients’ ages ranged from 59 to 81 years. Four patients underwent stoma construction because of rectal cancer, and 1 underwent stoma construction because of colon stenosis secondary to recurrent cancer. All patients were educated about their stoma and potential stoma-associated problems using three-dimensional stoma models, and all practiced cutting face plates using three-dimensional face plates. The models were also used during medical staff conferences to discuss current issues. All patients understood their problems and finally became self-reliant. The recent availability of three-dimensional printers has enabled the creation of many organ models, and full-scale stoma and face plate models are now available for patient education on cutting an appropriately individualized face plate. Thus, three-dimensional printers could enable fewer skin problems than are currently associated with daily stomal care.
Lee, Chia-Fone; Chen, Peir-Rong; Lee, Wen-Jeng; Chen, Jyh-Horng; Liu, Tien-Chen
2006-05-01
To present a systematic and practical approach that uses high-resolution computed tomography to derive models of the middle ear for finite element analysis. This prospective study included 31 subjects with normal hearing and no previous otologic disorders. Temporal bone images obtained from 15 right ears and 16 left ears were used for evaluation and reconstruction. High-resolution computed tomography of temporal bone was performed using simultaneous acquisition of 16 sections with a collimated slice thickness of 0.625 mm. All images were transferred to an Amira visualization system for three-dimensional reconstruction. The created three-dimensional model was translated into two commercial modeling packages, Patran and ANSYS, for finite element analysis. The characteristic dimensions of the model were measured and compared with previously published histologic section data. This result confirms that the geometric model created by the proposed method is accurate except that the tympanic membrane is thicker than when measured by the histologic section method. No obvious difference in the geometrical dimension between right and left ossicles was found (P > .05). The three-dimensional model created by finite element method and predicted umbo and stapes displacements are close to the bounds of the experimental curves of Nishihara's, Huber's, Gan's, and Sun's data across the frequency range of 100 to 8000 Hz. The model includes a description of the geometry of the middle ear components and dynamic equations of vibration. The proposed method is quick, practical, low-cost, and, most importantly, noninvasive as compared with histologic section methods.
Usefulness Of Three-Dimensional Printing Models for Patients with Stoma Construction
Tominaga, Tetsuro; Takagi, Katsunori; Takeshita, Hiroaki; Miyamoto, Tomo; Shimoda, Kozue; Matsuo, Ayano; Matsumoto, Keitaro; Hidaka, Shigekazu; Yamasaki, Naoya; Sawai, Terumitsu; Nagayasu, Takeshi
2016-01-01
The use of patient-specific organ models in three-dimensional printing systems could be helpful for the education of patients and medical students. The aim of this study was to clarify whether the use of patient-specific stoma models is helpful for patient education. From January 2014 to September 2014, 5 patients who underwent colorectal surgery and for whom a temporary or permanent stoma had been created were involved in this study. Three-dimensional stoma models and three-dimensional face ...
Schiek, Richard [Albuquerque, NM
2006-06-20
A method of generating two-dimensional masks from a three-dimensional model comprises providing a three-dimensional model representing a micro-electro-mechanical structure for manufacture and a description of process mask requirements, reducing the three-dimensional model to a topological description of unique cross sections, and selecting candidate masks from the unique cross sections and the cross section topology. The method further can comprise reconciling the candidate masks based on the process mask requirements description to produce two-dimensional process masks.
Three-dimensional Modeling of Water Quality and Ecology in Narragansett Bay
This report presents the methodology to apply, calibrate, and validate the three-dimensional water quality and ecological model provided with the Environmental Fluid Dynamics Code (EFDC). The required advection and dispersion mechanisms are generated simultaneously by the EFDC h...
A three-dimensional autonomous nonlinear dynamical system modelling equatorial ocean flows
Ionescu-Kruse, Delia
2018-04-01
We investigate a nonlinear three-dimensional model for equatorial flows, finding exact solutions that capture the most relevant geophysical features: depth-dependent currents, poleward or equatorial surface drift and a vertical mixture of upward and downward motions.
Probabilistic Three-Dimensional Model of an offshore Monopile Foundation
DEFF Research Database (Denmark)
Vahdatirad, Mohammad Javad; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo
2013-01-01
shear strength of the soil. Typically, measurement, statistical and model uncertainties are not taken into account in code - based, deterministic design. Hence, current methodology based design may be expensive, but the reliability of the foundation is unknown. Instead, a reliability - based design......When wind turbines are to be installed offshore, expensive geotechnical in-situ tests are carried out at the location of each turbine and only a quantile value (typically the 5% quantile) of the measured strength parameters is used as design parameter , e.g., the 5% quantile value of the undrained...... -element model is established and a stochastic model for the undrained shear strength of the soil is proposed using random field theory. The Mohr – Coulomb constitutive model is used to model the soil behavior. Reliability indices of the monopile are obtained through an advanced reliability method...
Probabilistic Three-Dimensional Model of an offshore Monopile Foundation
DEFF Research Database (Denmark)
Vahdatirad, Mohammad Javad; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo
2013-01-01
shear strength of the soil. Typically, measurement, statistical and model uncertainties are not taken into account in code - based, deterministic design. Hence, current methodology based design may be expensive, but the reliability of the foundation is unknown. Instead, a reliability - based design...... process based on stochastic analysis of the soil parameters is proposed to obtain an efficient design with known reliability and smaller costs for tests and construction. In this study a monopile foundation in undrained, over -consolidated clay is considered as an example. A three –dimensional (3D) finite...... -element model is established and a stochastic model for the undrained shear strength of the soil is proposed using random field theory. The Mohr – Coulomb constitutive model is used to model the soil behavior. Reliability indices of the monopile are obtained through an advanced reliability method...
Three-Dimensional Modeling of Glass Lens Molding
DEFF Research Database (Denmark)
Sarhadi, Ali; Hattel, Jesper Henri; Hansen, Hans Nørgaard
2015-01-01
The required accuracy for the final dimensions of the molded lenses in wafer-based precision glass molding as well as the need for elimination of costly experimental trial and error calls for numerical simulations. This study deals with 3D thermo-mechanical modeling of the wafer-based precision...... glass lens molding process. First, a comprehensive 3D thermo-mechanical model of glass is implemented into a FORTRAN user subroutine (UMAT) in the FE program ABAQUS, and the developed FE model is validated with both a well-known sandwich seal test and experimental results of precision molding of several...... glass rings. Afterward, 3D thermo-mechanical modeling of the wafer-based glass lens manufacturing is performed to suggest a proper molding program (i.e., the proper set of process parameters including preset force-time and temperature-time histories) for molding a wafer to a desired dimension...
Semantic description of three-dimensional models of Bologna porches
Directory of Open Access Journals (Sweden)
Massimo Ballabeni
2015-07-01
Full Text Available The study is part of a broader search coordinated by the Department of Architecture of the University of Bologna, the Cineca and the city of Bologna for the nomination of the city porticoes in the UNESCO World Heritage Site. The study describes, first, the problems and the methods adopted for the survey, the numerical modeling and visualization of the arcades models. In addition, the paper aims to describe a method for the semantic studying of the porticoes architecture and the segmentation of the models. The goal is also to establish an integrated approach to the semantic cataloguing of the Bologna arcades based on historical, material, formal, dimensional and theoretical data, and to make this information easily readable and communicable.
Chung, Hyemoon; Jeon, Byunghwan; Chang, Hyuk-Jae; Han, Dongjin; Shim, Hackjoon; Cho, In Jeong; Shim, Chi Young; Hong, Geu-Ru; Kim, Jung-Sun; Jang, Yangsoo; Chung, Namsik
2015-12-01
After left atrial appendage (LAA) device closure, peri-device leakage into the LAA persists due to incomplete occlusion. We hypothesized that pre-procedural three-dimensional (3D) geometric analysis of the interatrial septum (IAS) and LAA orifice can predict this leakage. We investigated the predictive parameters of LAA device closure obtained from baseline cardiac computerized tomography (CT) using a novel 3D analysis system. We conducted a retrospective study of 22 patients who underwent LAA device closure. We defined peri-device leakage as the presence of a Doppler signal inside the LAA after device deployment (group 2, n = 5) compared with patients without peri-device leakage (group 1, n = 17). Conventional parameters were measured by cardiac CT. Angles θ and φ were defined between the IAS plane and the line, linking the LAA orifice center and foramen ovale. Group 2 exhibited significantly better left atrial (LA) function than group 1 (p = 0.031). Pre-procedural θ was also larger in this group (41.9° vs. 52.3°, p = 0.019). The LAA cauliflower-type morphology was more common in group 2. Overall, the patients' LA reserve significantly decreased after the procedure (21.7 mm(3) vs. 17.8 mm(3), p = 0.035). However, we observed no significant interval changes in pre- and post-procedural values of θ and φ in either group (all p > 0.05). Angles between the IAS and LAA orifice might be a novel anatomical parameter for predicting peri-device leakage after LAA device closure. In addition, 3D CT analysis of the LA and LAA orifice could be used to identify clinically favorable candidates for LAA device closure.
Three-dimensional musculoskeletal modelling of the seated row ...
African Journals Online (AJOL)
Adjustments had to be made to the model to solve the forward dynamics simulations; as a result, no muscle forces or contraction values were obtained. This negatively influenced the value of the results as these parameters are important when analysing an exercise. The seated row resistance-training machine's engineered ...
Engineered three-dimensional multicellular culture model to ...
Tissue fusion during early mammalian development requires crosstalk between multiple cell types. For example, paracrine signaling between palatal epithelial cells and palatal mesenchyme mediates the fusion of opposing palatal shelves during embryonic development. Fusion events in developmental processes including heart development, neural tube closure, and palatal fusion are dependent on epithelial-mesenchymal interactions (EMIs) and specific signaling pathways that have been elucidated largely using gene knockout mouse models. A broad analysis of literature using ToxRefDB identified 63 ToxCast chemicals associated with cleft palate in animal models. However, the influence of these and other putative teratogens on human palatal fusion has not been examined in depth due to the lack of in vitro models incorporating EMIs between human cell types. We sought to engineer the stratified mesenchymal and epithelial structure of the developing palate in vitro using spheroid culture of human Wharton’s Jelly mesenchymal stem cells (hMSC). hMSC spheroids exhibited uniform size over time (175 ± 21 µm mean diameter) that was proportional to starting cell density. Further, hMSCs in spheroid culture exhibited increased alkaline phosphatase activity and increased expression of bglap and runx2 after 7 days of culture in osteo-induction medium, which suggests that spheroid culture together with osteo-induction medium supports osteogenic differentiation. We developed a novel pro
Weyl Phases in a Three Dimensional Network Model
Wang, Hailong; Chong, Yidong; theoretical photonics Team
We study the topological properties of 3D ``Floquet'' band structures, defined using unitary evolution matrices rather than Hamiltonians. Such band structures can be realized in coherent-wave networks or lattices subjected to time-periodic drives. Previously, 2D Floquet band structures have been shown to exhibit unusual topological behaviors such as topologically-nontrivial zero-Chern-number phases. Here, we analyze the Floquet band structure of a 3D network model, which exhibits an Floquet analogue of a Weyl phase. The surface states exhibit topologically-protected ``Fermi'' arcs, similar to the recently-discovered Weyl semi-metals; however, the Weyl points in different quasi-energy gaps are related by a particle-hole symmetry which is unique to the Floquet system. By tuning the coupling parameters of the network, we can drive a transition between conventional insulator, weak topological insulator, and Weyl phases. Finally, we discuss the possibility of realizing this model using custom-designed electromagnetic networks. GRANT: Supported by Singapore National Research Foundation under Grant No. NRFF2012-02.
Organotypic three-dimensional culture model of mesenchymal ...
Tissue fusion during early mammalian development requires coordination of multiple cell types, the extracellular matrix, and complex signaling pathways. Fusion events during processes including heart development, neural tube closure, and palatal fusion are dependent on signaling pathways elucidated using gene knockout mouse models. A broad analysis of literature, ToxRefDB, and ToxCast identified 63 chemicals that are related to cleft palate. However,the influence of these putative teratogens on human palatal fusion has not been studied due to the lack of in vitro models. We sought to engineer the stratified mesenchymal and epithelial structure of the developing palate in vitro via organotypic culture of human mesenchymal stem cell (hMSC) spheroids coated with a single layer of human primary epidermalkeratinocytes (hPEKp). hMSC spheroids exhibited uniform size over time (175 ± 21 µm mean diameter) proportional to starting cell density. Further, we developed a novel procedure to coat hMSC spheroids homogeneously with a single layer of hPEKp cells using a seeding ratio of 0.1-0.2 hPEKp per hMSC, and hMSC/hPEKp spheroids expressed mesenchymal markers (vim+, C044+, CD105+, CD34-) and epithelial markers (krt17+, itga6+) via qRT-PCR. Analysis of adverse outcome pathways related to palate fusion points to an EGF/TGFj33 switch that could be a target for cleft palate teratogens, and both egf and egfr were expressed by hMSC/hPEKp spheres. Finally, hMSCs and hPE
Comparing Three-Dimensional Geophysical Models of Mount St. Helens
Creager, K. C.; Ulberg, C. W.; Vidale, J. E.; Levander, A.; Kiser, E.; Abers, G. A.; Crosbie, K.; Mann, M. E.; Moran, S. C.; Denlinger, R. P.; Thelen, W. A.; Hansen, S. M.; Schmandt, B.; Schultz, A.; Bowles-martinez, E.; Bedrosian, P.; Peacock, J.; Hill, G.
2017-12-01
The iMUSH project integrates active- and passive-source seismic experiments with magnetotelluric (MT) observations and petrology to better understand the structure and dynamics of the Mount St. Helens (MSH) magmatic system from the subducted plate to the surface. The geophysical experiments included a two-year, 70-element broadband array with 10-km station spacing within 50 km of the MSH edifice, 23 shots recorded by geophones at 6000 sites including 900 Nodal stations, and 147 wideband MT stations with 6-km nominal station spacing. We have determined 3-D models of P-wave, S-wave and P/S-wave velocity as well as 3-D electrical resistivity. Our models from independent data sets and methodologies exhibit remarkable similarity. A narrow low-VP and VS anomaly as well as a high VP/VS and conductivity anomaly is well imaged by nearly all methods at about 6-15 km beneath MSH and coincides with a previously inferred magma storage volume. The St. Helens seismic zone (SHZ), which cuts through MSH with a NNW-SSE orientation, coincides with a narrow, vertical, planar zone of high electrical conductivity and low VP from the near surface to 15 km depth where we lose resolution. The continental Moho shows strong reflectivity east of the SHZ, but is weak to non-existent to the west, perhaps because this marks the eastern edge of hydrous mineral stability in the cold mantle wedge. Farther north, a similar high-conductivity feature is imaged along the west Rainer seismic zone. High Vp/Vs and high electrical conductivity extend under the Indian Heaven volcanic field at depths of 5-15 km, potentially associated with regions of partial melt and/or fluids. Mid- to lower-crustal velocities are generally fast to the west of MSH, consistent with the presence of the accreted Siletz terrane, and slow to the east suggesting both a change in composition and higher temperatures. Moderate lower-crustal resistivity is also present to the east, and is consistent with a small degree of partial melt
Pasta, Salvatore; Gentile, Giovanni; Raffa, Giuseppe M; Scardulla, Francesco; Bellavia, Diego; Luca, Angelo; Pilato, Michele; Scardulla, Cesare
2017-09-01
Bicuspid aortic valve (BAV)-associated ascending aneurysmal aortopathy (namely "bicuspid aortopathy") is a heterogeneous disease making surgeon predictions particularly challenging. Computational flow analysis can be used to evaluate the BAV-related hemodynamic disturbances, which likely lead to aneurysm enlargement and progression. However, the anatomic reconstruction process is time consuming so that predicting hemodynamic and structural evolution by computational modeling is unfeasible in routine clinical practice. The aim of the study was to design and develop a parametric program for three-dimensional (3D) representations of aneurysmal aorta and different BAV phenotypes starting from several measures derived by computed-tomography angiography (CTA). Assuming that wall shear stress (WSS) has an important implication on bicuspid aortopathy, computational flow analyses were then performed to estimate how different would such an important parameter be, if a parametric aortic geometry was used as compared to standard geometric reconstructions obtained by CTA scans. Morphologic parameters here documented can be used to rapidly model the aorta and any phenotypes of BAV. t-test and Bland-Altman plot demonstrated that WSS obtained by flow analysis of parametric aortic geometries was in good agreement with that obtained from the flow analysis of CTA-related geometries. The proposed program offers a rapid and automated tool for 3D anatomic representations of bicuspid aortopathy with promising application in routine clinical practice by reducing the amount of time for anatomic reconstructions. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
Liu, Lu; Kamm, Paul; García-Moreno, Francisco; Banhart, John; Pasini, Damiano
2017-10-01
This paper examines three-dimensional metallic lattices with regular octet and rhombicuboctahedron units fabricated with geometric imperfections via Selective Laser Sintering. We use X-ray computed tomography to capture morphology, location, and distribution of process-induced defects with the aim of studying their role in the elastic response, damage initiation, and failure evolution under quasi-static compression. Testing results from in-situ compression tomography show that each lattice exhibits a distinct failure mechanism that is governed not only by cell topology but also by geometric defects induced by additive manufacturing. Extracted from X-ray tomography images, the statistical distributions of three sets of defects, namely strut waviness, strut thickness variation, and strut oversizing, are used to develop numerical models of statistically representative lattices with imperfect geometry. Elastic and failure responses are predicted within 10% agreement from the experimental data. In addition, a computational study is presented to shed light into the relationship between the amplitude of selected defects and the reduction of elastic properties compared to their nominal values. The evolution of failure mechanisms is also explained with respect to strut oversizing, a parameter that can critically cause failure mode transitions that are not visible in defect-free lattices.
Software Package \\Nesvetay-3D" for modeling three-dimensional flows of monatomic rarefied gas
Directory of Open Access Journals (Sweden)
V. A. Titarev
2014-01-01
Full Text Available Analysis of three-dimensional rarefied gas flowsin microdevices (micropipes, micropumps etc and over re-entry vehicles requires development of methods of computational modelling. One of such methods is the direct numerical solution of the Boltzmann kinetic equation for the velocity distribution function with either exact or approximate (model collision integral. At present, for flows of monatomic rarefied gas the Shakhov model kinetic equation, also called S-model, has gained wide-spread use. The equation can be regarded as a model equation of the incomplete thirdorder approximation. Despite its relative simplicity, the S-model is still a complicated integrodifferential equation of high dimension. The numerical solution of such an equation requires high-accuracy parallel methods.The present work is a review of recent results concerning the development and application of three-dimensional computer package Nesvetay-3D intended for modelling of rarefied gas flows. The package solves Boltzmann kinetic equation with the BGK (Krook and Shakhov model collision integrals using the discrete velocity approach. Calculations are carried out in non-dimensional variables. A finite integration domain and a mesh are introduced in the molecular velocity space. Next, the kinetic equation is re-written as a system of kinetic equations for each of the discrete velocities. The system is solved using an implicit finite-volume method of Godunov type. The steady-state solution is computed by a time marching method. High order of spatial accuracy is achieved by using a piece-wise linear representation of the distribution function in each spatial cell. In general, the coefficients of such an approximation are found using the least-square method. Arbitrary unstructured meshes in the physical space can be used in calculations, which allow considering flows over objects of general geometrical shape. Conservative property of the method with respect to the model collision
Generation of three-dimensional prototype models based on cone beam computed tomography
International Nuclear Information System (INIS)
Lambrecht, J.T.; Berndt, D.C.; Zehnder, M.; Schumacher, R.
2009-01-01
The purpose of this study was to generate three-dimensional models based on digital volumetric data that can be used in basic and advanced education. Four sets of digital volumetric data were established by cone beam computed tomography (CBCT) (Accuitomo, J. Morita, Kyoto, Japan). Datasets were exported as Dicom formats and imported into Mimics and Magic software programs to separate the different tissues such as nerve, tooth and bone. These data were transferred to a Polyjet 3D Printing machine (Eden 330, Object, Israel) to generate the models. Three-dimensional prototype models of certain limited anatomical structures as acquired volumetrically were fabricated. Generating three-dimensional models based on CBCT datasets is possible. Automated routine fabrication of these models, with the given infrastructure, is too time-consuming and therefore too expensive. (orig.)
Generation of three-dimensional prototype models based on cone beam computed tomography
Energy Technology Data Exchange (ETDEWEB)
Lambrecht, J.T.; Berndt, D.C.; Zehnder, M. [University of Basel, Department of Oral Surgery, University Hospital for Oral Surgery, Oral Radiology and Oral Medicine, Basel (Switzerland); Schumacher, R. [University of Applied Sciences Northwestern Switzerland, School of Life Sciences, Institute for Medical and Analytical Technologies, Muttenz (Switzerland)
2009-03-15
The purpose of this study was to generate three-dimensional models based on digital volumetric data that can be used in basic and advanced education. Four sets of digital volumetric data were established by cone beam computed tomography (CBCT) (Accuitomo, J. Morita, Kyoto, Japan). Datasets were exported as Dicom formats and imported into Mimics and Magic software programs to separate the different tissues such as nerve, tooth and bone. These data were transferred to a Polyjet 3D Printing machine (Eden 330, Object, Israel) to generate the models. Three-dimensional prototype models of certain limited anatomical structures as acquired volumetrically were fabricated. Generating three-dimensional models based on CBCT datasets is possible. Automated routine fabrication of these models, with the given infrastructure, is too time-consuming and therefore too expensive. (orig.)
Development Report on the Idaho National Laboratory Sitewide Three-Dimensional Aquifer Model
Energy Technology Data Exchange (ETDEWEB)
Thomas R. Wood; Catherine M. Helm-Clark; Hai Huang; Swen Magnuson; Travis McLing; Brennon Orr; Michael J. Rohe; Mitchell A. Plummer; Robert Podgorney; Erik Whitmore; Michael S. Roddy
2007-09-01
A sub-regional scale, three-dimensional flow model of the Snake River Plain Aquifer was developed to support remediation decisions for Waste Area Group 10, Operable Unit 10 08 at the Idaho National Laboratory (INL) Site. This model has been calibrated primarily to water levels and secondarily to groundwater velocities interpreted from stable isotope disequilibrium studies and the movement of anthropogenic contaminants in the aquifer from facilities at the INL. The three-dimensional flow model described in this report is one step in the process of constructing a fully three-dimensional groundwater flow and contaminant transport model as prescribed in the Idaho National Engineering and Environmental Laboratory Operable Unit 10-08 Sitewide Groundwater Model Work Plan. An updated three-dimensional hydrogeologic conceptual model is presented along with the geologic basis for the conceptual model. Sediment-dominated three-dimensional volumes were used to represent the geology and constrain groundwater flow as part of the conceptual model. Hydrological, geochemical, and geological data were summarized and evaluated to infer aquifer behavior. A primary observation from development and evaluation of the conceptual model was that relative to flow on a regional scale, the aquifer can be treated with steady-state conditions. Boundary conditions developed for the three-dimensional flow model are presented along with inverse simulations that estimate parameterization of hydraulic conductivity. Inverse simulations were performed using the pilot-point method to estimate permeability distributions. Thermal modeling at the regional aquifer scale and at the sub-regional scale using the inverted permeabilities is presented to corroborate the results of the flow model. The results from the flow model show good agreement with simulated and observed water levels almost always within 1 meter. Simulated velocities show generally good agreement with some discrepancies in an interpreted low
International Nuclear Information System (INIS)
Thorne, P.D.; Chamness, M.A.; Spane, F.A. Jr.; Vermeul, V.R.; Webber, W.D.
1993-12-01
The ground water underlying parts of the Hanford Site (Figure 1.1) contains radioactive and chemical contaminants at concentrations exceeding regulatory standards (Dresel et al. 1993). The Hanford Site Ground-Water Surveillance Project, operated by Pacific Northwest Laboratory (PNL), is responsible for monitoring the movement of these contaminants to ensure that public health and the environment are protected. To support the monitoring effort, a sitewide three-dimensional ground-water flow model is being developed. This report provides an update on the status of the conceptual model that will form the basis for constructing a numerical three-dimensional flow model for, the site. Thorne and Chamness (1992) provide additional information on the initial development of the three-dimensional conceptual model
Energy Technology Data Exchange (ETDEWEB)
Lim, Hojun [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Owen, Steven J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Abdeljawad, Fadi F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hanks, Byron [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Battaile, Corbett Chandler [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-09-01
In order to better incorporate microstructures in continuum scale models, we use a novel finite element (FE) meshing technique to generate three-dimensional polycrystalline aggregates from a phase field grain growth model of grain microstructures. The proposed meshing technique creates hexahedral FE meshes that capture smooth interfaces between adjacent grains. Three dimensional realizations of grain microstructures from the phase field model are used in crystal plasticity-finite element (CP-FE) simulations of polycrystalline a -iron. We show that the interface conformal meshes significantly reduce artificial stress localizations in voxelated meshes that exhibit the so-called "wedding cake" interfaces. This framework provides a direct link between two mesoscale models - phase field and crystal plasticity - and for the first time allows mechanics simulations of polycrystalline materials using three-dimensional hexahedral finite element meshes with realistic topological features.
Three-dimensional semi-idealized model for tidal motion in tidal estuaries
Kumar, M.; Schuttelaars, H.M.; Roos, P.C.; Möller, M.
2015-01-01
In this paper, a three-dimensional semi-idealized model for tidal motion in a tidal estuary of arbitrary shape and bathymetry is presented. This model aims at bridging the gap between idealized and complex models. The vertical profiles of the velocities are obtained analytically in terms of the
Accounting for the influence of the Earth's sphericity in three-dimensional density modelling
Martyshko, P. S.; Byzov, D. D.; Chernoskutov, A. I.
2017-11-01
A method for transformation of the three-dimensional regional "flat" density models of the Earth's crust and upper mantle to the "spherical" models and vice versa is proposed. A computation algorithm and a method of meaningful comparison of the vertical component of the gravity field of both models are presented.
Heinen, M.
2014-01-01
A three-dimensional root length density distribution function is introduced that made it possible to compare two empirical uptake models with a more mechanistic uptake model. Adding a compensation component to the more empirical model resulted in predictions of root water uptake distributions
Hanegraef, Hester; Martinón-Torres, María; Martínez de Pinillos, Marina; Martín-Francés, Laura; Vialet, Amélie; Arsuaga, Juan Luis; Bermúdez de Castro, José María
2018-02-08
This study aims to explore the affinities of the Sima de los Huesos (SH) population in relation to Homo neanderthalensis, Arago, and early and contemporary Homo sapiens. By characterizing SH intra-population variation, we test current models to explain the Neanderthal origins. Three-dimensional reconstructions of dentine surfaces of lower first and second molars were produced by micro-computed tomography. Landmarks and sliding semilandmarks were subjected to generalized Procrustes analysis and principal components analysis. SH is often similar in shape to Neanderthals, and both groups are generally discernible from Homo sapiens. For example, the crown height of SH and Neanderthals is lower than for modern humans. Differences in the presence of a mid-trigonid crest are also observed, with contemporary Homo sapiens usually lacking this feature. Although SH and Neanderthals show strong affinities, they can be discriminated based on certain traits. SH individuals are characterized by a lower intra-population variability, and show a derived dental reduction in lower second molars compared to Neanderthals. SH also differs in morphological features from specimens that are often classified as Homo heidelbergensis, such as a lower crown height and less pronounced mid-trigonid crest in the Arago fossils. Our results are compatible with the idea that multiple evolutionary lineages or populations coexisted in Europe during the Middle Pleistocene, with the SH paradigm phylogenetically closer to Homo neanderthalensis. Further research could support the possibility of SH as a separate taxon. Alternatively, SH could be a subspecies of Neanderthals, with the variability of this clade being remarkably higher than previously thought. © 2018 Wiley Periodicals, Inc.
Three-dimensional stochastic model of actin–myosin binding in the sarcomere lattice
Energy Technology Data Exchange (ETDEWEB)
Mijailovich, Srboljub M.; Kayser-Herold, Oliver; Stojanovic, Boban; Nedic, Djordje; Irving, Thomas C.; Geeves, MA (Harvard); (IIT); (U. Kent); (Kragujevac)
2016-11-18
The effect of molecule tethering in three-dimensional (3-D) space on bimolecular binding kinetics is rarely addressed and only occasionally incorporated into models of cell motility. The simplest system that can quantitatively determine this effect is the 3-D sarcomere lattice of the striated muscle, where tethered myosin in thick filaments can only bind to a relatively small number of available sites on the actin filament, positioned within a limited range of thermal movement of the myosin head. Here we implement spatially explicit actomyosin interactions into the multiscale Monte Carlo platform MUSICO, specifically defining how geometrical constraints on tethered myosins can modulate state transition rates in the actomyosin cycle. The simulations provide the distribution of myosin bound to sites on actin, ensure conservation of the number of interacting myosins and actin monomers, and most importantly, the departure in behavior of tethered myosin molecules from unconstrained myosin interactions with actin. In addition, MUSICO determines the number of cross-bridges in each actomyosin cycle state, the force and number of attached cross-bridges per myosin filament, the range of cross-bridge forces and accounts for energy consumption. At the macroscopic scale, MUSICO simulations show large differences in predicted force-velocity curves and in the response during early force recovery phase after a step change in length comparing to the two simplest mass action kinetic models. The origin of these differences is rooted in the different fluxes of myosin binding and corresponding instantaneous cross-bridge distributions and quantitatively reflects a major flaw of the mathematical description in all mass action kinetic models. Consequently, this new approach shows that accurate recapitulation of experimental data requires significantly different binding rates, number of actomyosin states, and cross-bridge elasticity than typically used in mass action kinetic models to
Ground-water solute transport modeling using a three-dimensional scaled model
International Nuclear Information System (INIS)
Crider, S.S.
1987-01-01
Scaled models are used extensively in current hydraulic research on sediment transport and solute dispersion in free surface flows (rivers, estuaries), but are neglected in current ground-water model research. Thus, an investigation was conducted to test the efficacy of a three-dimensional scaled model of solute transport in ground water. No previous results from such a model have been reported. Experiments performed on uniform scaled models indicated that some historical problems (e.g., construction and scaling difficulties; disproportionate capillary rise in model) were partly overcome by using simple model materials (sand, cement and water), by restricting model application to selective classes of problems, and by physically controlling the effect of the model capillary zone. Results from these tests were compared with mathematical models. Model scaling laws were derived for ground-water solute transport and used to build a three-dimensional scaled model of a ground-water tritium plume in a prototype aquifer on the Savannah River Plant near Aiken, South Carolina. Model results compared favorably with field data and with a numerical model. Scaled models are recommended as a useful additional tool for prediction of ground-water solute transport
DEFF Research Database (Denmark)
Røge, Mads Sønderstrup; Andersen, Thomas Lykke
The present report presents results from a three-dimensional model test study carried out at Aalborg University in the period June 2015 – August 2015. The objectives of the model tests were to study the stability of the Xbloc armoured breakwaters at Punta Catalina under short-crested wave attack...
A Fully Implicit Model of the Three-Dimensional Thermohaline Ocean Circulation
Dijkstra, Henk A.; Oksuzoglu, Hakan; Wubs, Fred. W.; Botta, Eugen F.F.
2001-01-01
In this paper, a fully implicit numerical model of the three-dimensional thermohaline ocean circulation is presented. With this numerical model it is possible to follow branches of steady states in parameter space and monitor their linear stability. Also, transient flows can be computed allowing
The Role of Peer Tutoring: Steps to Describing a Three-Dimensional Model.
Davis, Kevin
A comprehensive, three-dimensional model of peer tutoring, constructed by gathering current theories and research and locating them on a dynamic continuum of the tutoring process, allows researchers to break new ground in tutor research and might eventually offer a new heuristic for training peer tutors. The first axis in the model, the focus…
A three-dimensional multiscale model for gas exchange in fruit.
Ho, Quang Tri; Verboven, Pieter; Verlinden, Bert E; Herremans, Els; Wevers, Martine; Carmeliet, Jan; Nicolaï, Bart M
2011-03-01
Respiration of bulky plant organs such as roots, tubers, stems, seeds, and fruit depends very much on oxygen (O2) availability and often follows a Michaelis-Menten-like response. A multiscale model is presented to calculate gas exchange in plants using the microscale geometry of the tissue, or vice versa, local concentrations in the cells from macroscopic gas concentration profiles. This approach provides a computationally feasible and accurate analysis of cell metabolism in any plant organ during hypoxia and anoxia. The predicted O2 and carbon dioxide (CO2) partial pressure profiles compared very well with experimental data, thereby validating the multiscale model. The important microscale geometrical features are the shape, size, and three-dimensional connectivity of cells and air spaces. It was demonstrated that the gas-exchange properties of the cell wall and cell membrane have little effect on the cellular gas exchange of apple (Malus×domestica) parenchyma tissue. The analysis clearly confirmed that cells are an additional route for CO2 transport, while for O2 the intercellular spaces are the main diffusion route. The simulation results also showed that the local gas concentration gradients were steeper in the cells than in the surrounding air spaces. Therefore, to analyze the cellular metabolism under hypoxic and anoxic conditions, the microscale model is required to calculate the correct intracellular concentrations. Understanding the O2 response of plants and plant organs thus not only requires knowledge of external conditions, dimensions, gas-exchange properties of the tissues, and cellular respiration kinetics but also of microstructure.
A Three-Dimensional Multiscale Model for Gas Exchange in Fruit1[C][W][OA
Ho, Quang Tri; Verboven, Pieter; Verlinden, Bert E.; Herremans, Els; Wevers, Martine; Carmeliet, Jan; Nicolaï, Bart M.
2011-01-01
Respiration of bulky plant organs such as roots, tubers, stems, seeds, and fruit depends very much on oxygen (O2) availability and often follows a Michaelis-Menten-like response. A multiscale model is presented to calculate gas exchange in plants using the microscale geometry of the tissue, or vice versa, local concentrations in the cells from macroscopic gas concentration profiles. This approach provides a computationally feasible and accurate analysis of cell metabolism in any plant organ during hypoxia and anoxia. The predicted O2 and carbon dioxide (CO2) partial pressure profiles compared very well with experimental data, thereby validating the multiscale model. The important microscale geometrical features are the shape, size, and three-dimensional connectivity of cells and air spaces. It was demonstrated that the gas-exchange properties of the cell wall and cell membrane have little effect on the cellular gas exchange of apple (Malus × domestica) parenchyma tissue. The analysis clearly confirmed that cells are an additional route for CO2 transport, while for O2 the intercellular spaces are the main diffusion route. The simulation results also showed that the local gas concentration gradients were steeper in the cells than in the surrounding air spaces. Therefore, to analyze the cellular metabolism under hypoxic and anoxic conditions, the microscale model is required to calculate the correct intracellular concentrations. Understanding the O2 response of plants and plant organs thus not only requires knowledge of external conditions, dimensions, gas-exchange properties of the tissues, and cellular respiration kinetics but also of microstructure. PMID:21224337
The use of frequency resolution in echolocation for modeling three dimensional environments.
Huebschman, Benjamin D
2010-12-01
Bats use echolocation to navigate three dimensional obstacles while locating, identifying, and engaging targets. A theory is offered of image processing during the search and navigation phase of echolocation that uses Doppler frequency shifts. The information in frequency changes across the angle of elevation can be used to generate a three dimensional model of the environment when combined with the timing and the relative amplitude of the returned signals. The mathematics of frequency shifts for an emitter traveling at a large fraction of the velocity of propagation (c) is presented. Reported behavior that can be explained by this phenomenon is discussed.
A three-dimensional breakdown model of SOI lateral power transistors with a circular layout
International Nuclear Information System (INIS)
Guo Yufeng; Wang Zhigong; Sheu Gene
2009-01-01
This paper presents an analytical three-dimensional breakdown model of SOI lateral power devices with a circular layout. The Poisson equation is solved in cylindrical coordinates to obtain the radial surface potential and electric field distributions for both fully- and partially-depleted drift regions. The breakdown voltages for N + N and P + N junctions are derived and employed to investigate the impact of cathode region curvature. A modified RESURF criterion is proposed to provide a design guideline for optimizing the breakdown voltage and doping concentration in the drift region in three dimensional space. The analytical results agree well with MEDICI simulation results and experimental data from earlier publications. (semiconductor devices)
Bauer-Gottwein, P.; . Gondwe, B. R. N.; Christiansen, L.; Kgotlhang, L.; Herckenrath, D.; Zimmermann, S.
2009-04-01
The time-domain electromagnetic method (TDEM) has been widely used in groundwater exploration and geological mapping applications. TDEM measures the subsurface electrical conductivity, which is strongly correlated with groundwater salinity. TDEM thus offers cheap and non-invasive ways to map saltwater intrusion and groundwater salinization. Typically, TDEM data is interpreted using 1D layered-earth models of the subsurface. However, most saltwater intrusion and groundwater salinization phenomena produce eminently three-dimensional anomalies. To fully exploit the information of TDEM data in this context, three-dimensional modeling of the TDEM response is required. We present a finite-element solution for three-dimensional forward modeling of TDEM responses from arbitrary subsurface electrical conductivity distributions. As an application example, the groundwater salinization process on islands in the Okavango Delta is simulated using a variable-density flow and salinity transport model. The transport model outputs are subsequently converted to TDEM responses using the 3D TDEM forward code. A field dataset of ground-based and airborne TDEM data from a selected Okavango Delta island is presented. The TDEM field data cannot be interpreted in terms of 1D layered-earth models, because of the strongly three-dimensional nature of the salinity anomaly under the island. A 3D interpretation of the field data allows detailed and consistent mapping of this anomaly.
Three-dimensional virtual model and animation of penile lengthening surgery.
Wang, Ruiheng; Yang, Dongyun; Li, Shirong
2012-10-01
Three-dimensional digital models, animations, and simulations have been used in the plastic surgical field for surgical education and training and patient education. In penile lengthening surgery, proper patient selection and well-designed surgical interventions are necessary; however, no such surgical or patient education tool exists. Using magnetic resonance images as references, a preliminary three-dimensional digital model of the penis with its adjacent structures was constructed using Amira 5. This preliminary model was imported into Maya 2009, a computer modeling and animation software program, for processing to correct many defects. The refined model was used to create digital animation of penile lengthening surgery, including ordered steps of the procedure, using Maya 2009 and Adobe After Effects CS4. A three-dimensional digital animation was created to illustrate penile lengthening surgery. All major surgical steps were demonstrated, including exposure, transversal incision of the fundiform ligament, partial division and release of the suspensory ligament. Three-dimensional digital models and animations of penile lengthening surgery may serve as resources for patient education to facilitate patient selection and resident education outside the operating room. Copyright © 2012 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.
Fusing range and intensity images for generating dense models of three-dimensional environments
DEFF Research Database (Denmark)
Ellekilde, Lars-Peter; Miró, Jaime Valls; Dissanayake., Gamini
This paper presents a novel strategy for the construction of dense three-dimensional environment models by combining images from a conventional camera and a range imager. Ro- bust data association is ?rst accomplished by exploiting the Scale Invariant Feature Transformation (SIFT) technique...
Three-dimensional modelling of thrust-controlled foreland basin stratigraphy
Clevis, Q. (Quintijn)
2003-01-01
In this thesis a tectono-sedimentary forward model has been presented, devised to simulate sediment erosion and deposition in a coupled drainage basin - foreland system, as well as accumulating a three-dimensional stratigraphy. The aim of the research was to investigate which features recorded in
and three-dimensional models for analysis of optical absorption in ...
Indian Academy of Sciences (India)
Unknown
Goldberg et al 1975; Kam and Parkinson 1982; Baglio et al 1982, 1983; Oritz 1995; Li et al 1996) has been carried out on WS2, there is no detailed analysis of the absorption spectra obtained from the single crystals of WS2 on the basis of two- and three-dimensional models. We have therefore carried out this study and the.
Articular contact in a three-dimensional model of the knee
Blankevoort, L.; Kuiper, J. H.; Huiskes, R.; Grootenboer, H. J.
1991-01-01
This study is aimed at the analysis of articular contact in a three-dimensional mathematical model of the human knee-joint. In particular the effect of articular contact on the passive motion characteristics is assessed in relation to experimentally obtained joint kinematics. Two basically different
On two-dimensionalization of three-dimensional turbulence in shell models
DEFF Research Database (Denmark)
Chakraborty, Sagar; Jensen, Mogens Høgh; Sarkar, A.
2010-01-01
Applying a modified version of the Gledzer-Ohkitani-Yamada (GOY) shell model, the signatures of so-called two-dimensionalization effect of three-dimensional incompressible, homogeneous, isotropic fully developed unforced turbulence have been studied and reproduced. Within the framework of shell...
Three-dimensional dynamic models of subducting plate-overriding plate-upper mantle interaction
Meyer, Clio; Schellart, W. P.
2013-01-01
We present fully dynamic generic three-dimensional laboratory models of progressive subduction with an overriding plate and a weak subduction zone interface. Overriding plate thickness (TOP) is varied systematically (in the range 0-2.5 cm scaling to 0-125 km) to investigate its effect on subduction
Two-and three-dimensional models for analysis of optical absorption ...
Indian Academy of Sciences (India)
The optical energy gaps of WS2 single crystal were determined from the analysis of the absorption spectrum near the fundamental absorption edge at room temperature using light parallel to -axis incident normally on the basal plane. On the basis of two- and three-dimensional models it was found that both direct and ...
Design and Validation of a Three-Dimensional Printed Flexible Canine Otoscopy Teaching Model
Nibblett, Belle Marie D.; Pereira, Mary Mauldin; Sithole, Fortune; Orchard, Paul A.D.; Bauman, Eric B.
2017-01-01
Introduction A teaching model was sought to improve canine otoscopy skill and reduce use of teaching dogs. Methods An otoscopy teaching model was printed in a flexible medium on a desktop three-dimensional printer from a magnetic resonance image of a canine external ear canal. The model was mounted in a polyvinyl dog mannequin. Validation of the teaching model was sought from student, faculty, and dog perspective. Student perception of prelaboratory training was assessed using a survey regard...
Analytical model for three-dimensional Mercedes-Benz water molecules
Urbic, T.
2012-01-01
We developed a statistical model which describes the thermal and volumetric properties of water-like molecules. A molecule is presented as a three-dimensional sphere with four hydrogen-bonding arms. Each water molecule interacts with its neighboring waters through a van der Waals interaction and an orientation-dependent hydrogen-bonding interaction. This model, which is largely analytical, is a variant of a model developed before for a two-dimensional Mercedes-Benz model of water. We explored...
THREE-DIMENSIONAL SIMULATION OF FLOW AT AN OPEN-CHANNEL CONFLUENCE WITH TURBULENCE MODELS
Dinh Thanh, Mung; Kimura, Ichiro; Shimizu, Yasuyuki
Open-channel confluence flows are common in natural river systems as well as in environmental and hydraulic engineering, such as in river engineering. Often, these flows are three-dimensional and complex,while numerical studies fully describing confluence flow are still few. This paper presents the results of investigation of confluence flow using a three-dimensional numerical model with the linear and nonlinear k-ε models. To treat the dynamic boundary condition at the free surface, non-hydrostatic pressure is included in the present model. The model is validated using the experimental data available. Adequacy of the present model with two turbulence models above is indicated based on the result analysis. The nonlinear model is indicated as the more advantageous one than the linear one.
Three-dimensional dose-response models of risk for radiation injury carcinogenesis
International Nuclear Information System (INIS)
Raabe, O.G.
1988-01-01
The use of computer graphics in conjunction with three-dimensional models of dose-response relationships for chronic exposure to ionizing radiation dramaticly clarifies the separate and interactive roles of competing risks. The three dimensions are average dose rate, exposure time, and risk. As an example, the functionally injurious and carcinogenic responses after systemic uptake of Ra-226 by beagles, mice and people with consequent alpha particle irradiation of the bone are represented by three-dimensional dose-rate/time/response surfaces that demonstrate the contributions with the passage of time of the competing deleterious responses. These relationships are further evaluated by mathematical stripping with three-dimensional illustrations that graphically show the resultant separate contribution of each effect. Radiation bone injury predominates at high dose rates and bone cancer at intermediate dose rates. Low dose rates result in spontaneous deaths from natural aging, yielding a type of practical threshold for bone cancer induction. Risk assessment is benefited by the insights that become apparent with these three-dimensional models. The improved conceptualization afforded by them contributes to planning and evaluating epidemiological analyses and experimental studies
Development of a three dimensional circulation model based on fractional step method
Directory of Open Access Journals (Sweden)
Mazen Abualtayef
2010-03-01
Full Text Available A numerical model was developed for simulating a three-dimensional multilayer hydrodynamic and thermodynamic model in domains with irregular bottom topography. The model was designed for examining the interactions between flow and topography. The model was based on the three-dimensional Navier-Stokes equations and was solved using the fractional step method, which combines the finite difference method in the horizontal plane and the finite element method in the vertical plane. The numerical techniques were described and the model test and application were presented. For the model application to the northern part of Ariake Sea, the hydrodynamic and thermodynamic results were predicted. The numerically predicted amplitudes and phase angles were well consistent with the field observations.
Upper ocean ecosystem dynamics and iron cycling in a global three-dimensional model
Moore, J. Keith; Doney, Scott C; Lindsay, Keith
2004-01-01
A global three-dimensional marine ecosystem model with several key phytoplankton functional groups, multiple limiting nutrients, explicit iron cycling, and a mineral ballast/organic matter parameterization is run within a global ocean circulation model. The coupled biogeochemistry/ecosystem/circulation (BEC) model reproduces known basin-scale patterns of primary and export production, biogenic silica production, calcification, chlorophyll, macronutrient and dissolved iron concentrations. The ...
Wagner, Roger; Modla, Shannon; Hossler, Fred; Czymmek, Kirk
2012-08-01
We examined the three-dimensional organization of the endothelial vesicular system with TEM tomography of semi-thick sections. Mouse abdominal muscle capillaries were perfused with terbium to label vesicular compartments open to the luminal surface. The tissue was prepared for TEM and semi-thick (250 nm) sections were cut. Dual axis tilt series, collected from +60° to -60° at 1° increments, were acquired in regions of labeled abluminal caveolae. These tomograms were reconstructed and analyzed to reveal three-dimensional vesicular associations not evident in thin sections. Reconstructed tomograms revealed free vesicles, both labeled and unlabeled, in the endothelial cytoplasm as well as transendothelial channels that spanned the luminal and abluminal membranes. A large membranous compartment connecting the luminal and abluminal surfaces was also present. Computer modeling of tomographic data and video animations provided three-dimensional perspectives to these structures. Uncertainties associated with other three-dimensional methods to study the capillary wall are remedied by tomographic analysis of semi-thick sections. Transendothelial channels of fused vesicles and free cytoplasmic vesicles give credence to their role as large pores in the transport of solutes across the walls of continuous capillaries. © 2012 John Wiley & Sons Ltd.
DEFF Research Database (Denmark)
Salimzadeh, Saeed; Paluszny, Adriana; Nick, Hamidreza M.
2018-01-01
A fully coupled thermal-hydraulic-mechanical (THM) finite element model is presented for fractured geothermal reservoirs. Fractures are modelled as surface discontinuities within a three-dimensional matrix. Non-isothermal flow through the rock matrix and fractures are defined and coupled to a mec......A fully coupled thermal-hydraulic-mechanical (THM) finite element model is presented for fractured geothermal reservoirs. Fractures are modelled as surface discontinuities within a three-dimensional matrix. Non-isothermal flow through the rock matrix and fractures are defined and coupled....... The model has been validated against several analytical solutions, and applied to study the effects of the deformable fractures on the injection of cold water in fractured geothermal systems. Results show that the creation of flow channelling due to the thermal volumetric contraction of the rock matrix...
Homminga, J.; Hekman, E. E. G.; Veldhuizen, A. G.; Verkerke, G. J.; Meijer, G.
2010-01-01
During adolescent growth, vertebrae and intervertebral discs undergo various geometrical changes. Although such changes in geometry are well known, their effects on spinal stiffness remains poorly understood. However, this understanding is essential in the treatment of spinal abnormalities during
Wang, Q; Yang, Y; Fei, Q; Li, D; Li, J J; Meng, H; Su, N; Fan, Z H; Wang, B Q
2017-06-06
Objective: To build a three-dimensional finite element models of a modified posterior cervical single open-door laminoplasty with short-segmental lateral mass screws fusion. Methods: The C(2)-C(7) segmental data were obtained from computed tomography (CT) scans of a male patient with cervical spondylotic myelopathy and spinal stenosis.Three-dimensional finite element models of a modified cervical single open-door laminoplasty (before and after surgery) were constructed by the combination of software package MIMICS, Geomagic and ABAQUS.The models were composed of bony vertebrae, articulating facets, intervertebral disc and associated ligaments.The loads of moments 1.5Nm at different directions (flexion, extension, lateral bending and axial rotation)were applied at preoperative model to calculate intersegmental ranges of motion.The results were compared with the previous studies to verify the validation of the models. Results: Three-dimensional finite element models of the modified cervical single open- door laminoplasty had 102258 elements (preoperative model) and 161 892 elements (postoperative model) respectively, including C(2-7) six bony vertebraes, C(2-3)-C(6-7) five intervertebral disc, main ligaments and lateral mass screws.The intersegmental responses at the preoperative model under the loads of moments 1.5 Nm at different directions were similar to the previous published data. Conclusion: Three-dimensional finite element models of the modified cervical single open- door laminoplasty were successfully established and had a good biological fidelity, which can be used for further study.
A comparison of two- and three-dimensional stochastic models of regional solute movement
Shapiro, A.M.; Cvetkovic, V.D.
1990-01-01
Recent models of solute movement in porous media that are based on a stochastic description of the porous medium properties have been dedicated primarily to a three-dimensional interpretation of solute movement. In many practical problems, however, it is more convenient and consistent with measuring techniques to consider flow and solute transport as an areal, two-dimensional phenomenon. The physics of solute movement, however, is dependent on the three-dimensional heterogeneity in the formation. A comparison of two- and three-dimensional stochastic interpretations of solute movement in a porous medium having a statistically isotropic hydraulic conductivity field is investigated. To provide an equitable comparison between the two- and three-dimensional analyses, the stochastic properties of the transmissivity are defined in terms of the stochastic properties of the hydraulic conductivity. The variance of the transmissivity is shown to be significantly reduced in comparison to that of the hydraulic conductivity, and the transmissivity is spatially correlated over larger distances. These factors influence the two-dimensional interpretations of solute movement by underestimating the longitudinal and transverse growth of the solute plume in comparison to its description as a three-dimensional phenomenon. Although this analysis is based on small perturbation approximations and the special case of a statistically isotropic hydraulic conductivity field, it casts doubt on the use of a stochastic interpretation of the transmissivity in describing regional scale movement. However, by assuming the transmissivity to be the vertical integration of the hydraulic conductivity field at a given position, the stochastic properties of the hydraulic conductivity can be estimated from the stochastic properties of the transmissivity and applied to obtain a more accurate interpretation of solute movement. ?? 1990 Kluwer Academic Publishers.
Multi-GPU hybrid programming accelerated three-dimensional phase-field model in binary alloy
Directory of Open Access Journals (Sweden)
Changsheng Zhu
2018-03-01
Full Text Available In the process of dendritic growth simulation, the computational efficiency and the problem scales have extremely important influence on simulation efficiency of three-dimensional phase-field model. Thus, seeking for high performance calculation method to improve the computational efficiency and to expand the problem scales has a great significance to the research of microstructure of the material. A high performance calculation method based on MPI+CUDA hybrid programming model is introduced. Multi-GPU is used to implement quantitative numerical simulations of three-dimensional phase-field model in binary alloy under the condition of multi-physical processes coupling. The acceleration effect of different GPU nodes on different calculation scales is explored. On the foundation of multi-GPU calculation model that has been introduced, two optimization schemes, Non-blocking communication optimization and overlap of MPI and GPU computing optimization, are proposed. The results of two optimization schemes and basic multi-GPU model are compared. The calculation results show that the use of multi-GPU calculation model can improve the computational efficiency of three-dimensional phase-field obviously, which is 13 times to single GPU, and the problem scales have been expanded to 8193. The feasibility of two optimization schemes is shown, and the overlap of MPI and GPU computing optimization has better performance, which is 1.7 times to basic multi-GPU model, when 21 GPUs are used.
Multi-GPU hybrid programming accelerated three-dimensional phase-field model in binary alloy
Zhu, Changsheng; Liu, Jieqiong; Zhu, Mingfang; Feng, Li
2018-03-01
In the process of dendritic growth simulation, the computational efficiency and the problem scales have extremely important influence on simulation efficiency of three-dimensional phase-field model. Thus, seeking for high performance calculation method to improve the computational efficiency and to expand the problem scales has a great significance to the research of microstructure of the material. A high performance calculation method based on MPI+CUDA hybrid programming model is introduced. Multi-GPU is used to implement quantitative numerical simulations of three-dimensional phase-field model in binary alloy under the condition of multi-physical processes coupling. The acceleration effect of different GPU nodes on different calculation scales is explored. On the foundation of multi-GPU calculation model that has been introduced, two optimization schemes, Non-blocking communication optimization and overlap of MPI and GPU computing optimization, are proposed. The results of two optimization schemes and basic multi-GPU model are compared. The calculation results show that the use of multi-GPU calculation model can improve the computational efficiency of three-dimensional phase-field obviously, which is 13 times to single GPU, and the problem scales have been expanded to 8193. The feasibility of two optimization schemes is shown, and the overlap of MPI and GPU computing optimization has better performance, which is 1.7 times to basic multi-GPU model, when 21 GPUs are used.
Inverse modeling of pumping tests to parameterize three-dimensional hydrofacies models
Medina-Ortega, P.; Morales-Casique, E.; Escolero-Fuentes, O.; Hernandez Espriu, A.
2013-05-01
We model the spatial distribution of hydrofacies in the aquifer of Mexico City and present a procedure for parameterizing those hydrofacies by inverse modeling of pumping tests . The aquifer is composed of a highly heterogeneous mixture of alluvial deposits and volcanic rocks. Lithological records from 111 production water wells are analyzed using indicator geostatistics. The different lithological categories are grouped into four hydrofacies, where a hydrofacies is a set of lithological categories which have similar hydraulic properties. An exponential variogram model was fitted to each hydrofacies by minimizing cross validation errors. The data set is then kriged to obtain the three-dimensional distribution of each hydrofacies within the alluvial aquifer of Mexico City. We present a procedure to parameterize the four hydrofacies by inverse modeling of two pumping tests and test the predictive capabilities of the inversion results by forward modeling of two more pumping tests.
Patient-specific three-dimensional composite bone models for teaching and operation planning.
Matthews, Felix; Messmer, Peter; Raikov, Vladislav; Wanner, Guido A; Jacob, Augustinus L; Regazzoni, Pietro; Egli, Adrian
2009-10-01
Orthopedic trauma care relies on two-dimensional radiograms both before and during the operation. Understanding the three-dimensional nature of complex fractures on plain radiograms is challenging. Modern fluoroscopes can acquire three-dimensional volume datasets even during an operation, but the device limitations constrain the acquired volume to a cube of only 12-cm edge. However, viewing the surrounding intact structures is important to comprehend the fracture in its context. We suggest merging a fluoroscope's volume scan into a generic bone model to form a composite full-length 3D bone model. Materials consisted of one cadaver bone and 20 three-dimensional surface models of human femora. Radiograms and computed tomography scans were taken before and after applying a controlled fracture to the bone. A 3D scan of the fracture was acquired using a mobile fluoroscope (Siemens Siremobil). The fracture was fitted into the generic bone models by rigid registration using a modified least-squares algorithm. Registration precision was determined and a clinical appraisal of the composite models obtained. Twenty composite bone models were generated. Average registration precision was 2.0 mm (range 1.6 to 2.6). Average processing time on a laptop computer was 35 s (range 20 to 55). Comparing synthesized radiograms with the actual radiograms of the fractured bone yielded clinically satisfactory results. A three-dimensional full-length representation of a fractured bone can reliably be synthesized from a short scan of the patient's fracture and a generic bone model. This patient-specific model can subsequently be used for teaching, surgical operation planning, and intraoperative visualization purposes.
A Three-Dimensional Model of the Gas-Cell Atomic Frequency Standard.
1988-02-25
Clock Model Calculations ......................................................... 8 11. Exponents for Power-Law Formulas: oy -P a, S -P B, and PY...iz not substantiated oy the three-dimensional model. Considering Fig. 4 and Table IIi, it is more accurate tu state that the clock’s frequency offset...1985). [71 H. E. Williams, T. M. Kwon and T. McClelland, "Compact rectangular cavity for rubidium vapor cell frequency standards," Proceeding of the
Li He Ping; Chen, X
2003-01-01
In this paper, physical/mathematical models for the three-dimensional, quasi-steady modelling of the plasma flow and heat transfer inside a non-transferred DC arc plasma torch are described in detail. The Steenbeck's minimum principle (Finkelnburg W and Maecker H 1956 Electric arcs and thermal plasmas Encyclopedia of Physics vol XXII (Berlin: Springer)) is employed to determine the axial position of the anode arc-root at the anode surface. This principle postulates a minimum arc voltage for a given arc current, working gas flow rate, and torch configuration. The modelling results show that the temperature and flow fields inside the DC non-transferred arc plasma torch show significant three-dimensional features. The predicted anode arc-root attachment position and the arc shape by employing Steenbeck's minimum principle are reasonably consistent with experimental observations. The thermal efficiency and the torch power distribution are also calculated in this paper. The results show that the thermal efficiency...
Three-dimensional model of stellacyanin and its implications for electron transfer reactivity
DEFF Research Database (Denmark)
Wherland, S; Farver, O; Pecht, I
1988-01-01
Experimental data were combined with computational methods in constructing a hypothetical three-dimensional model for the blue single copper protein Rhus stellacyanin (St). The known sequence of stellacyanin and its homology with plastocyanin (Pc) were used together with the results of spectrosco......Experimental data were combined with computational methods in constructing a hypothetical three-dimensional model for the blue single copper protein Rhus stellacyanin (St). The known sequence of stellacyanin and its homology with plastocyanin (Pc) were used together with the results....... The structure also indicates that a carbonyl oxygen atom is near the copper, thus the site may have analogy to the Alcaligenes denitrificans azurin (Az) site, although the amino acid sequence is more homologous to that of Pc. The model indicates that aspartate 49, reductively labeled by Cr(III), is near...
Käpylä, Elli; Aydogan, Dogu Baran; Virjula, Sanni; Vanhatupa, Sari; Miettinen, Susanna; Hyttinen, Jari; Kellomäki, Minna
2012-11-01
Traditional scaffold fabrication methods used in tissue engineering enable only limited control over essential parameters such as porosity, pore size and pore interconnectivity. In this study, we designed and fabricated five different types of three-dimensionally interconnected, highly porous scaffolds with precise control over the scaffold characteristics. We used two-photon polymerization (2PP) with a commercial polymer-ceramic material (Ormocomp®) for scaffold fabrication. Also for the first time, we analyzed the 2PP fabrication accuracy with respect to scaffold design parameters. Our results showed that the porosity values decreased up to 13% compared to the design specifications due to the fabrication process and the shrinkage of the material. Finally, we showed that our scaffolds supported human adipose stem cell adhesion and proliferation in a six day culture. By precise tuning of scaffold parameters, our design and fabrication method provides a novel approach for studying the effect of scaffold architecture on cell behavior in vitro.
Application of data mining in three-dimensional space time reactor model
International Nuclear Information System (INIS)
Jiang Botao; Zhao Fuyu
2011-01-01
A high-fidelity three-dimensional space time nodal method has been developed to simulate the dynamics of the reactor core for real time simulation. This three-dimensional reactor core mathematical model can be composed of six sub-models, neutron kinetics model, cay heat model, fuel conduction model, thermal hydraulics model, lower plenum model, and core flow distribution model. During simulation of each sub-model some operation data will be produced and lots of valuable, important information reflecting the reactor core operation status could be hidden in, so how to discovery these information becomes the primary mission people concern. Under this background, data mining (DM) is just created and developed to solve this problem, no matter what engineering aspects or business fields. Generally speaking, data mining is a process of finding some useful and interested information from huge data pool. Support Vector Machine (SVM) is a new technique of data mining appeared in recent years, and SVR is a transformed method of SVM which is applied in regression cases. This paper presents only two significant sub-models of three-dimensional reactor core mathematical model, the nodal space time neutron kinetics model and the thermal hydraulics model, based on which the neutron flux and enthalpy distributions of the core are obtained by solving the three-dimensional nodal space time kinetics equations and energy equations for both single and two-phase flows respectively. Moreover, it describes that the three-dimensional reactor core model can also be used to calculate and determine the reactivity effects of the moderator temperature, boron concentration, fuel temperature, coolant void, xenon worth, samarium worth, control element positions (CEAs) and core burnup status. Besides these, the main mathematic theory of SVR is introduced briefly next, on the basis of which SVR is applied to dealing with the data generated by two sample calculation, rod ejection transient and axial
Fei, Qi; Li, Qiu-jun; Yang, Yong; Li, Dong; Tang, Hai; Li, Jin-jun; Wang, Bing-qiang; Wang, Yi-peng
2010-11-09
To build a three-dimensional finite element model of thoracolumbar spine with osteoporotic vertebral compression fracture (OVCF) and analyze its biomechanical change. The T10-L2 segment data were obtained from computed tomography (CT) scans of an elderly female with a single T12 OVCF. A three-dimensional finite element model of thoracolumbar spine was constructed with the MIMICS and ABAQUS software. The model was composed of bony vertebrae, articulating facets, intervertebral disc and associated ligaments. The basic stress analysis of T10-L2 motion segment was made for different material properties of bone, ligaments and facet joints contacting frictional property. The stress on the annulus fiber, nucleus pulposus, endplate and facet joints under axial pressure (0.3 MPa, 1.0 MPa, 4.0 MPa) were analyzed. A three-dimensional finite element model of human T12-L2 motion segment had 617468 elements. And the stress was higher in vertebral body than posterior structure. The distribution of pressure stresses in intervertebral disc was asymmetrical. The stress increased with a rising axial pressure. 3D finite element model of thoracolumbar OVCF and adjacent segments are successfully established. The results of stress analysis are both feasible and reliable.
Experiments with three-dimensional riblets as an idealized model of shark skin
Energy Technology Data Exchange (ETDEWEB)
Bechert, D.W.; Bruse, M.; Hage, W. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Berlin (Germany). Dept. of Turbulence Res.
2000-05-01
The skin of fast sharks exhibits a rather intriguing three-dimensional rib pattern. Therefore, the question arises whether or not such three-dimensional riblet surfaces may produce an equivalent or even higher drag reduction than straight two-dimensional riblets. Previously, the latter have been shown to reduce turbulent wall shear stress by up to 10%. Hence, the drag reduction by three-dimensional riblet surfaces is investigated experimentally. Our idealized 3D-surface consists of sharp-edged fin-shaped elements arranged in an interlocking array. The turbulent wall shear stress on this surface is measured using direct force balances. In a first attempt, wind tunnel experiments with about 365000 tiny fin elements per test surface have been carried out. Due to the complexity of the surface manufacturing process, a comprehensive parametric study was not possible. These initial wind tunnel data, however, hinted at an appreciable drag reduction. Subsequently, in order to have a better judgement on the potential of these 3D-surfaces, oil channel experiments are carried out. In our new oil channel, the geometrical dimensions of the fins can be magnified 10 times in size as compared to the initial wind tunnel experiments, i.e., from typically 0.5 mm to 5 mm. For these latter oil channel experiments, novel test plates with variable fin configuration have been manufactured, with 1920-4000 fins. This enhanced variability permits measurements with a comparatively large parameter range. As a result of our measurements, it can be concluded, that 3D-riblet surfaces do indeed produce an appreciable drag reduction. We found as much as 7.3% decreased turbulent shear stress, as compared to a smooth reference plate.
Koshigai, Masaru; Marui, Atsunao; Ito, Narimitsu; Yoshizawa, Takuya
An optimum groundwater management which achieved a good balance between conservation and utilization is required to use the groundwater as sustainable water resources. On the recent groundwater management which uses a numerical simulation, it is important to understand the full breadth of groundwater basin and groundwater storage for evaluation the extent of human impact. However, previous study has not been clarified the full breadth of them throughout Japan, because basic information on the groundwater has not maintained still enough. The present work developed the three dimensional hydrogeological model in Japanese islands using the related database. And the groundwater storage was estimated based on the three dimensional hydrogeological model. As a result, to evaluate the full breadth of groundwater basin became possible from the sharply wide-range distribution of stratum. Moreover, we succeeded in providing the useful information such as development potential of unused groundwater resources for groundwater conservation and development.
Three-dimensional dynamic response modeling of floating nuclear plants using finite element methods
International Nuclear Information System (INIS)
Johnson, H.W.; Vaish, A.K.; Porter, F.L.; McGeorge, R.
1976-01-01
A modelling technique which can be used to obtain the dynamic response of a floating nuclear plant (FNP) moored in an artificial basin is presented. Hydrodynamic effects of the seawater in the basin have a significant impact on the response of the FNP and must be included. A three-dimensional model of the platform and mooring system (using beam elements) is used, with the hydrodynamic effects represented by added mass and damping. For an essentially square plant in close proximity to the site structures, the three-dimensional nature of the basin must be considered in evaluating the added mass and damping. However, direct solutions for hydrodynamic effects with complex basin geometry are not, as yet, available. A method for estimating these effects from planar finite element analysis is developed. (Auth.)
Fast three-dimensional core optimization based on modified one-group model
International Nuclear Information System (INIS)
Freire, Fernando S.; Martinez, Aquilino S.; Silva, Fernando C. da
2009-01-01
The optimization of any nuclear reactor core is an extremely complex process that consumes a large amount of computer time. Fortunately, the nuclear designer can rely on a variety of methodologies able to approximate the analysis of each available core loading pattern. Two-dimensional codes are usually used to analyze the loading scheme. However, when particular axial effects are present in the core, two-dimensional analysis cannot produce good results and three-dimensional analysis can be required at all time. Basically, in this paper are presented the major advantages that can be found when one use the modified one-group diffusion theory coupled with a buckling correction model in optimization process. The results of the proposed model are very accurate when compared to benchmark results obtained from detailed calculations using three-dimensional nodal codes (author)
Fast three-dimensional core optimization based on modified one-group model
Energy Technology Data Exchange (ETDEWEB)
Freire, Fernando S. [ELETROBRAS Termonuclear S.A. - ELETRONUCLEAR, Rio de Janeiro, RJ (Brazil). Dept. GCN-T], e-mail: freire@eletronuclear.gov.br; Martinez, Aquilino S.; Silva, Fernando C. da [Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear], e-mail: aquilino@con.ufrj.br, e-mail: fernando@con.ufrj.br
2009-07-01
The optimization of any nuclear reactor core is an extremely complex process that consumes a large amount of computer time. Fortunately, the nuclear designer can rely on a variety of methodologies able to approximate the analysis of each available core loading pattern. Two-dimensional codes are usually used to analyze the loading scheme. However, when particular axial effects are present in the core, two-dimensional analysis cannot produce good results and three-dimensional analysis can be required at all time. Basically, in this paper are presented the major advantages that can be found when one use the modified one-group diffusion theory coupled with a buckling correction model in optimization process. The results of the proposed model are very accurate when compared to benchmark results obtained from detailed calculations using three-dimensional nodal codes (author)
Vasiliadou, I. A.; Katzourakis, V. E.; Syngouna, V. I.; Chrysikopoulos, C. V.
2012-04-01
This study is focused on the transport of Pseudomonas (P.) putida bacterial cells in a three-dimensional model aquifer. The pilot-scale aquifer consisted of a rectangular glass tank with internal dimensions: 120 cm length, 48 cm width, and 50 cm height, carefully packed with well-characterized quartz sand. The P. putida attachment onto the aquifer sand was determined with batch experiments, and was adequately described by a linear isotherm. Transport experiments with a conservative tracer and P. putida were conducted to characterize the aquifer and to investigate the bacterial behavior during transport in water saturated porous media. A three-dimensional, finite-difference numerical model for bacterial transport in saturated, homogeneous porous media was developed and was used to successfully fit the experimental data. Furthermore, theoretical interaction energy calculations suggested that the extended DLVO theory seems to predict bacteria attachment onto the aquifer sand better than the classical DLVO theory.
Verifying Three-Dimensional Skull Model Reconstruction Using Cranial Index of Symmetry
Kung, Woon-Man; Chen, Shuo-Tsung; Lin, Chung-Hsiang; Lu, Yu-Mei; Chen, Tzu-Hsuan; Lin, Muh-Shi
2013-01-01
BACKGROUND: Difficulty exists in scalp adaptation for cranioplasty with customized computer-assisted design/manufacturing (CAD/CAM) implant in situations of excessive wound tension and sub-cranioplasty dead space. To solve this clinical problem, the CAD/CAM technique should include algorithms to reconstruct a depressed contour to cover the skull defect. Satisfactory CAM-derived alloplastic implants are based on highly accurate three-dimensional (3-D) CAD modeling. Thus, it is quite important ...
Tyszka, J M
1997-01-01
Three-dimensional models can be generated from slice images, such as those obtained from computed tomography (CT) and magnetic resonance imaging (MRI) using a variety of techniques. A popular method for rendering 3D anatomical models is the creation of polygonal mesh surfaces representing the boundary between tissues. Mesh surfaces can be rendered extremely quickly using conventional personal computers, without recourse to more expensive graphic workstations. The dissemination of three-dimensional (3D) models across the Internet has been made significantly easier by the definition of the Virtual Reality Markup Language (VRML) format. The VRML definition allows the parameters and relationships of 3D objects to be described in a text format. The text file can be transfered from a host computer to a remote client computer through the World Wide Web and viewed using readily available software (See Appendix). VRML is based on the definition of primitive 3D objects such as polygons and spheres. Consequently, the transition from a mesh surface derived from a clinical image data set to a VRML object is relatively simple, allowing for convenient and cost-effective dissemination of 3D clinical models across the internet.
Prechapanich, Japarath; Kajihara, Takeshi; Fujita, Keiko; Sato, Kazuko; Uchino, Satomi; Tanaka, Kayoko; Matsumoto, Sachiko; Akita, Masumi; Nagashima, Masabumi; Brosens, Jan J; Ishihara, Osamu
2014-12-01
The pathogenesis of endometriosis remains poorly understood at least in part because early stages of the disease process are difficult to investigate. Previous studies have proposed a three-dimensional fibrin matrix culture model to study human endometriosis. We examined the ultrastructural features of the endometriosis in this model and assessed the effect of a progestin on endometrial outgrowth and apoptosis in this culture system. Endometrial explants were placed in three-dimensional fibrin matrix culture and treated with and without various concentrations of the progestin dienogest. By the second week, endometrial gland-like formation was established in outgrowths both attached to and at a distance from the explants. These cells formed a combination of clumps and tubular monolayers surrounding a central cavity. Electron microscopy demonstrated that these cells are polarized with microvilli on the apical surface, desmosome-like structures, and basement membrane; features consistent with glandular epithelial cells. Outgrowth of endometrial stromal cells and glandular formation was impaired in response to dienogest in a dose-dependent manner. Our study shows that the human endometrial explants cultured in three-dimensional fibrin matrix establish outgrowths that ultrastructurally resemble ectopic endometrial implants. This model may provide insight into the cellular processes leading to endometriosis formation and enables screening of therapeutic compounds.
International Nuclear Information System (INIS)
Johnson, H.W.; Vaish, A.K.; Porter, F.L.; McGeorge, R.
1975-01-01
A modelling technique which can be used to obtain the dynamic response of a floating nuclear plant (FNP) moored in an artificial basin is presented. Hydrodynamic effects of the seawater in the basin have a significant impact on the response of the FNP and must be included. A three dimensional model of the platform and mooring system (using beam elements) is used, with the hydrodynamic effects represented by added mass and damping. For an essentially square plant in close proximity to the site structures, the three dimensional nature of the basin must be considered in evaluating the added mass and damping. A method for estimating these effects from planer finite element analyses is developed. The accuracy of the planar finite element model in obtaining two-dimensional added mass and damping is shown through comparison with existing the documented results. In addition, a comparison is shown for open ocean added mass and damping with a three-dimensional solution using velocity potential functions. It is concluded that the overall technique results in a reasonable and conservative calculation of the dynamic response of the floating nuclear plant. (orig./HP) [de
Three Dimensional Explicit Model for Cometary Tail Ions Interactions with Solar Wind
Al Bermani, M. J. F.; Alhamed, S. A.; Khalaf, S. Z.; Ali, H. Sh.; Selman, A. A.
2009-06-01
The different interactions between cometary tail and solar wind ions are studied in the present paper based on three-dimensional Lax explicit method. The model used in this research is based on the continuity equations describing the cometary tail-solar wind interactions. Three dimensional system was considered in this paper. Simulation of the physical system was achieved using computer code written using Matlab 7.0. The parameters studied here assumed Halley comet type and include the particle density rho, the particles velocity v, the magnetic field strength B, dynamic pressure p and internal energy E. The results of the present research showed that the interaction near the cometary nucleus is mainly affected by the new ions added to the plasma of the solar wind, which increases the average molecular weight and result in many unique characteristics of the cometary tail. These characteristics were explained in the presence of the IMF.
Ouazzani, Jalil; Rosenberger, Franz
1990-01-01
A systematic numerical study of the MOCVD of GaAs from trimethylgallium and arsine in hydrogen or nitrogen carrier gas at atmospheric pressure is reported. Three-dimensional effects are explored for CVD reactors with large and small cross-sectional aspect ratios, and the effects on growth rate uniformity of tilting the susceptor are investigated for various input flow rates. It is found that, for light carrier gases, thermal diffusion must be included in the model. Buoyancy-driven three-dimensional flow effects can greatly influence the growth rate distribution through the reactor. The importance of the proper design of the lateral thermal boundary conditions for obtaining layers of uniform thickness is emphasized.
Three-dimensional sound localisation with a lizard peripheral auditory model
DEFF Research Database (Denmark)
Kjær Schmidt, Michael; Shaikh, Danish
-related transfer functions [Cheng and Wakefield 2001]. Here we present a preliminary sensorimotor approach [Aytekin et al. 2007; Shaikh 2012] in simulation to three-dimensional sound source localisation employing two simulated microphones. We use directed spatial movements of the microphones to resolve the unknown......Conventional approaches for three-dimensional sound source localisation utilise either interaural time difference information extracted via static two-dimensional multi-microphone grids [Imran et al. 2016] with at least four microphones, or spectral cues [Keyrouz 2014; Reddy et al. 2016] via head...... information in a single plane which by itself is insufficient to localise the acoustic target in three dimensions. A multi-layer perceptron neural network is used to combine two independent responses of the model, corresponding to two rotational movements, into an estimate of the sound direction in terms...
Three dimensional global modeling of atmospheric CO2. Final technical report
International Nuclear Information System (INIS)
Fung, I.; Hansen, J.; Rind, D.
1983-01-01
A modeling effort has been initiated to study the prospects of extracting information on carbon dioxide sources and sinks from observed CO 2 variations. The approach uses a three-dimensional global transport model, based on winds from a 3-D general circulation model (GCM), to advect CO 2 noninteractively, i.e., as a tracer, with specified sources and sinks of CO 2 at the surface. This report identifies the 3-D model employed in this study and discusses biosphere, ocean and fossil fuel sources and sinks. Some preliminary model results are presented. 14 figures
Comparison of three-dimensional ocean general circulation models on a benchmark problem
International Nuclear Information System (INIS)
Chartier, M.
1990-12-01
A french and an american Ocean General Circulation Models for deep-sea disposal of radioactive wastes are compared on a benchmark test problem. Both models are three-dimensional. They solve the hydrostatic primitive equations of the ocean with two different finite difference techniques. Results show that the dynamics simulated by both models are consistent. Several methods for the running of a model from a known state are tested in the French model: the diagnostic method, the prognostic method, the acceleration of convergence and the robust-diagnostic method
Integration of a Three-Dimensional Process-Based Hydrological Model into the Object Modeling System
Directory of Open Access Journals (Sweden)
Giuseppe Formetta
2016-01-01
Full Text Available The integration of a spatial process model into an environmental modeling framework can enhance the model’s capabilities. This paper describes a general methodology for integrating environmental models into the Object Modeling System (OMS regardless of the model’s complexity, the programming language, and the operating system used. We present the integration of the GEOtop model into the OMS version 3.0 and illustrate its application in a small watershed. OMS is an environmental modeling framework that facilitates model development, calibration, evaluation, and maintenance. It provides innovative techniques in software design such as multithreading, implicit parallelism, calibration and sensitivity analysis algorithms, and cloud-services. GEOtop is a physically based, spatially distributed rainfall-runoff model that performs three-dimensional finite volume calculations of water and energy budgets. Executing GEOtop as an OMS model component allows it to: (1 interact directly with the open-source geographical information system (GIS uDig-JGrass to access geo-processing, visualization, and other modeling components; and (2 use OMS components for automatic calibration, sensitivity analysis, or meteorological data interpolation. A case study of the model in a semi-arid agricultural catchment is presented for illustration and proof-of-concept. Simulated soil water content and soil temperature results are compared with measured data, and model performance is evaluated using goodness-of-fit indices. This study serves as a template for future integration of process models into OMS.
A three-dimensional non-isothermal model for a membraneless direct methanol redox fuel cell
Wei, Lin; Yuan, Xianxia; Jiang, Fangming
2018-05-01
In the membraneless direct methanol redox fuel cell (DMRFC), three-dimensional electrodes contribute to the reduction of methanol crossover and the open separator design lowers the system cost and extends its service life. In order to better understand the mechanisms of this configuration and further optimize its performance, the development of a three-dimensional numerical model is reported in this work. The governing equations of the multi-physics field are solved based on computational fluid dynamics methodology, and the influence of the CO2 gas is taken into consideration through the effective diffusivities. The numerical results are in good agreement with experimental data, and the deviation observed for cases of large current density may be related to the single-phase assumption made. The three-dimensional electrode is found to be effective in controlling methanol crossover in its multi-layer structure, while it also increases the flow resistance for the discharging products. It is found that the current density distribution is affected by both the electronic conductivity and the concentration of reactants, and the temperature rise can be primarily attributed to the current density distribution. The sensitivity and reliability of the model are analyzed through the investigation of the effects of cell parameters, including porosity values of gas diffusion layers and catalyst layers, methanol concentration and CO2 volume fraction, on the polarization characteristics.
Penny, Matthew R.; Cao, Zi Jing; Patel, Bhaven; dos Santos, Bruno Sil; Asquith, Christopher R. M.; Szulc, Blanka R.; Rao, Zenobia X.; Muwaffak, Zaid; Malkinson, John P.; Hilton, Stephen T.
2017-01-01
Three-dimensional (3D) chemical models are a well-established learning tool used to enhance the understanding of chemical structures by converting two-dimensional paper or screen outputs into realistic three-dimensional objects. While commercial atom model kits are readily available, there is a surprising lack of large molecular and orbital models…
Sergovich, Aimee; Johnson, Marjorie; Wilson, Timothy D.
2010-01-01
The anatomy of the pelvis is complex, multilayered, and its three-dimensional organization is conceptually difficult for students to grasp. The aim of this project was to create an explorable and projectable stereoscopic, three-dimensional (3D) model of the female pelvis and pelvic contents for anatomical education. The model was created using…
Three-dimensional dose-response models of competing risks and natural life span
International Nuclear Information System (INIS)
Raabe, O.G.
1987-01-01
Three-dimensional dose-rate/time/response surfaces for chronic exposure to carcinogens, toxicants, and ionizing radiation dramatically clarify the separate and interactive roles of competing risks. The three dimensions are average dose rate, exposure time, and risk. An illustration with computer graphics shows the contributions with the passage of time of the competing risks of death from radiation pneumonitis/fibrosis, lung cancer, and natural aging consequent to the inhalation of plutonium-239 dioxide by beagles. These relationships are further evaluated by mathematical stripping with three-dimensional illustrations that graphically show the resultant separate contribution of each fatal effect. Radiation pneumonitis predominates at high dose rates and lung cancer at intermediate dose rates. Low dose rates result in spontaneous deaths from natural aging, yielding a type of practical threshold for lung cancer induction. Risk assessment is benefited by the insights that become apparent with these three-dimensional models. The improved conceptualization afforded by them contributes to the planning and evaluation of epidemiological analyses and experimental studies involving chronic exposure to toxicants
Three-Dimensional Model for Preservation and Restoration of Architectural Heritage
Marchis, Elena
2011-01-01
Thc aim of the research will be to create a model, three-dimensional mathematical. implementation. consultation and assistance to "large" restoration projects that will assist the structural analysis, allowing easier display of dynamic strain. analysis and lighting noise. It could also be a valuable tool for decision support. therefore. may simulate several possible scenarios for intervention, This model appears therefore an excellent support for recovering. ordering and monitoring information about materials and data (stage of restoration. photographs. sampling points. results of diagnostic tests, etc.) collected dynamically during the "life" of the cultural heritage. allowing to document its complete history
Modeling flow and shear stress fields over unsteady three dimensional dunes
Hardy, Richard; Parsons, Dan; Ashworth, Phil; Reesink, Arjan; Best, Jim
2014-05-01
The flow field over dunes has been extensively measured in laboratory conditions and there is general understanding on the nature of the flow over dunes formed under equilibrium flow conditions. This has allowed an understanding of bed shear stress to be derived and the development of morpho-dynamic models. However, fluvial systems typically experience unsteady flow and therefore the sediment-water interface is constantly responding and reorganizing to these unsteady flows and stresses, over a range of both spatial and temporal scales. This is primarily through the adjustment of bed forms (including ripples, dunes and bar forms) which then subsequently alter the flow field. This paper investigates, through the application of a numerical model, the influence of these roughness elements on the overall flow and bed shear stress. A series of physical experiments were undertaken in a flume, 16m long and 2m wide, where a fine sand (D50 of 239µm) was water worked under a range of unsteady hydraulic conditions to generate a series of quasi-equilibrium three dimensional bed forms. During the experiments flow was measured with acoustic Doppler velocimeters, (aDv's). On four occasions the flume was drained and the bed topography measured with terrestrial LiDAR to create digital elevation models. This data provide the necessary boundary conditions and validation data for a numerical three dimensional flow model. The prediction of flow over the four static beds demonstrates the spatial distribution of shear stress and the potential sediment transport paths between the dune crests. These appear to be associated with coherent flow structures formed by localized shear flow. These flow predictions are currently being used to develop a fully three dimensional morphodynamic model to further understand dune dynamics under unsteady flow conditions.
Three-Dimensional, Transgenic Cell Models to Quantify Space Genotoxic Effects
Gonda, S. R.; Sognier, M. A.; Wu, H.; Pingerelli, P. L.; Glickman, B. W.; Dawson, David L. (Technical Monitor)
1999-01-01
The space environment contains radiation and chemical agents known to be mutagenic and carcinogenic to humans. Additionally, microgravity is a complicating factor that may modify or synergize induced genotoxic effects. Most in vitro models fail to use human cells (making risk extrapolation to humans more difficult), overlook the dynamic effect of tissue intercellular interactions on genotoxic damage, and lack the sensitivity required to measure low-dose effects. Currently a need exists for a model test system that simulates cellular interactions present in tissue, and can be used to quantify genotoxic damage induced by low levels of radiation and chemicals, and extrapolate assessed risk to humans. A state-of-the-art, three-dimensional, multicellular tissue equivalent cell culture model will be presented. It consists of mammalian cells genetically engineered to contain multiple copies of defined target genes for genotoxic assessment,. NASA-designed bioreactors were used to coculture mammalian cells into spheroids, The cells used were human mammary epithelial cells (H184135) and Stratagene's (Austin, Texas) Big Blue(TM) Rat 2 lambda fibroblasts. The fibroblasts were genetically engineered to contain -a high-density target gene for mutagenesis (60 copies of lacl/LacZ per cell). Tissue equivalent spheroids were routinely produced by inoculation of 2 to 7 X 10(exp 5) fibroblasts with Cytodex 3 beads (150 micrometers in diameter). at a 20:1 cell:bead ratio, into 50-ml HARV bioreactors (Synthecon, Inc.). Fibroblasts were cultured for 5 days, an equivalent number of epithelial cells added, and the fibroblast/epithelial cell coculture continued for 21 days. Three-dimensional spheroids with diameters ranging from 400 to 600 micrometers were obtained. Histological and immunohistochemical Characterization revealed i) both cell types present in the spheroids, with fibroblasts located primarily in the center, surrounded by epithelial cells; ii) synthesis of extracellular matrix
THREE DIMENSIONAL MODELING VIA PHOTOGRAPHS FOR DOCUMENTATION OF A VILLAGE BATH
Directory of Open Access Journals (Sweden)
H. B. Balta
2013-07-01
Full Text Available The aim of this study is supporting the conceptual discussions of architectural restoration with three dimensional modeling of monuments based on photogrammetric survey. In this study, a 16th century village bath in Ulamış, Seferihisar, and Izmir is modeled for documentation. Ulamış is one of the historical villages within which Turkish population first settled in the region of Seferihisar – Urla. The methodology was tested on an antique monument; a bath with a cubical form. Within the limits of this study, only the exterior of the bath was modeled. The presentation scale for the bath was determined as 1 / 50, considering the necessities of designing structural interventions and architectural ones within the scope of a restoration project. The three dimensional model produced is a realistic document presenting the present situation of the ruin. Traditional plan, elevation and perspective drawings may be produced from the model, in addition to the realistic textured renderings and wireframe representations. The model developed in this study provides opportunity for presenting photorealistic details of historical morphologies in scale. Compared to conventional drawings, the renders based on the 3d models provide an opportunity for conceiving architectural details such as color, material and texture. From these documents, relatively more detailed restitution hypothesis can be developed and intervention decisions can be taken. Finally, the principles derived from the case study can be used for 3d documentation of historical structures with irregular surfaces.
Three-dimensional (3-D) Circumplex Model and revised scoring of FACES III.
Olson, D H
1991-03-01
FACES III can, however, continue to be a useful scale now that the Circumplex Model has been expanded into a three-dimensional design. Past and future studies would benefit from using FACES III as a linear dimension with high scores representing Balanced types and low scores representing Extreme types. This approach means that many past studies with FACES III need to be re-analyzed and/or re-interpreted in light of this 3-D Model. This revised scoring will significantly increase the number of studies that support the basic hypotheses of the Circumplex model, that Balanced families tend to function in more effective ways. It is clear from more recent work with the Clinical Rating Scale (CRS) that the lack of support for the curvilinear hypotheses of the Circumplex Model is due to the limitations of the FACES instrument and not the underlying theoretical model. The CRS clearly demonstrated the curvilinear pattern that has been hypothesized. It is important that future studies using FACES III analyze data in a linear way that fits with the three-dimensional model. In this way, there is a better match conceptually and methodologically between FACES III and the Circumplex Model. It is also highly recommended that future studies use both the self-report of FACES and the observational approaches to family assessment of the Clinical Rating Scale. This combined approach will help advance the field conceptually, methodologically, and clinically.
On the use of effective stress in three-dimensional hydro-mechanical coupled model
International Nuclear Information System (INIS)
Arairo, W.; Prunier, F.; Djeran-Maigre, I.; Millard, A.
2014-01-01
In the last decades, a number of hydro-mechanical elastoplastic constitutive models for unsaturated soils have been proposed. Those models couple the hydraulic and mechanical behaviour of unsaturated soils, and take into account the effects of the degree of saturation on the stress-strain behaviour and the effects of deformation on the soil-water characteristic response with a simple reversible part for the hysteresis. In addition, the influence of the suction on the stress-strain behaviour is considered. However, until now, few models predict the stress-strain and soil-water characteristic responses of unsaturated soils in a fully three-dimensional Finite Element code. This paper presents the predictions of an unsaturated soil model in a Three-dimensional Framework, and develops a study on the effect of partial saturation on the stability of shallow foundation resting on unsaturated silty soil. Qualitative predictions of the constitutive model show that incorporating a special formulation for the effective stress into an elastoplastic coupled hydro-mechanical model opens a full range of possibilities in modelling unsaturated soil behaviour. (authors)
Three-dimensional two-phase mass transport model for direct methanol fuel cells
International Nuclear Information System (INIS)
Yang, W.W.; Zhao, T.S.; Xu, C.
2007-01-01
A three-dimensional (3D) steady-state model for liquid feed direct methanol fuel cells (DMFC) is presented in this paper. This 3D mass transport model is formed by integrating five sub-models, including a modified drift-flux model for the anode flow field, a two-phase mass transport model for the porous anode, a single-phase model for the polymer electrolyte membrane, a two-phase mass transport model for the porous cathode, and a homogeneous mist-flow model for the cathode flow field. The two-phase mass transport models take account the effect of non-equilibrium evaporation/ condensation at the gas-liquid interface. A 3D computer code is then developed based on the integrated model. After being validated against the experimental data reported in the literature, the code was used to investigate numerically transport behaviors at the DMFC anode and their effects on cell performance
Experiments with three-dimensional riblets as an idealized model of shark skin
Bechert, D. W.; Bruse, M.; Hage, W.
The skin of fast sharks exhibits a rather intriguing three-dimensional rib pattern. Therefore, the question arises whether or not such three-dimensional riblet surfaces may produce an equivalent or even higher drag reduction than straight two-dimensional riblets. Previously, the latter have been shown to reduce turbulent wall shear stress by up to 10%. Hence, the drag reduction by three-dimensional riblet surfaces is investigated experimentally. Our idealized 3D-surface consists of sharp-edged fin-shaped elements arranged in an interlocking array. The turbulent wall shear stress on this surface is measured using direct force balances. In a first attempt, wind tunnel experiments with about 365,000 tiny fin elements per test surface have been carried out. Due to the complexity of the surface manufacturing process, a comprehensive parametric study was not possible. These initial wind tunnel data, however, hinted at an appreciable drag reduction. Subsequently, in order to have a better judgement on the potential of these 3D-surfaces, oil channel experiments are carried out. In our new oil channel, the geometrical dimensions of the fins can be magnified 10 times in size as compared to the initial wind tunnel experiments, i.e., from typically 0.5mm to 5mm. For these latter oil channel experiments, novel test plates with variable fin configuration have been manufactured, with 1,920-4,000 fins. This enhanced variability permits measurements with a comparatively large parameter range. As a result of our measurements, it can be concluded, that 3D-riblet surfaces do indeed produce an appreciable drag reduction. We found as much as 7.3% decreased turbulent shear stress, as compared to a smooth reference plate. However, in direct comparison with 2D riblets, the performance of 3D-riblets is still inferior by about 1.7%. On the other hand, it appears conceivable, with a careful design of the fin shape (possibly supported by theory), that this inferiority in performance might be
Three-dimensional patient-specific cardiac model for surgical planning in Nikaidoh procedure.
Valverde, Israel; Gomez, Gorka; Gonzalez, Antonio; Suarez-Mejias, Cristina; Adsuar, Alejandro; Coserria, Jose Felix; Uribe, Sergio; Gomez-Cia, Tomas; Hosseinpour, Amir Reza
2015-04-01
To explore the use of three-dimensional patient-specific cardiovascular models using rapid prototyping techniques (fused deposition modelling) to improve surgical planning in patients with complex congenital heart disease. Rapid prototyping techniques are used to print accurate three-dimensional replicas of patients' cardiovascular anatomy based on magnetic resonance images using computer-aided design systems. Models are printed using a translucent polylactic acid polymer. As a proof of concept, a model of the heart of a 1.5-year-old boy with transposition of the great arteries, ventricular septal defect and pulmonary stenosis was constructed to help planning the surgical correction. The cardiac model allowed the surgeon to evaluate the location and dimensions of the ventricular septal defect as well as its relationship with the aorta and pulmonary artery. Cardiovascular models constructed by rapid prototyping techniques are extremely helpful for planning corrective surgery in patients with complex congenital malformations. Therefore they may potentially reduce operative time and morbi-mortality.
A Simple Technique For Visualising Three Dimensional Models in Landscape Contexts
Directory of Open Access Journals (Sweden)
Stuart Jeffrey
2001-05-01
Full Text Available One of the Scottish Early Medieval Sculptured Stones project (SEMSS project's objectives is to generate accurate three dimensional models of these monuments using a variety of data capture techniques from photogrammetry to Time of Flight laser measurement. As the landscape context of these monuments is often considered crucial to their understanding, the model's ultimate presentation to the user should include some level of contextual information. In addition there are a number of presentation issues that must be considered such as interactivity, the relationship of reconstructed to non-reconstructed sections, lighting and suitability for presentation over the WWW. This article discusses the problem of presenting three dimensional models of monumental stones in their landscape contexts. This problem is discussed in general, but special attention is paid to the difficulty of capturing landscape detail,interactivity, reconstructing landscapes and providing accurate representations of landscapes to the horizon. Comparison is made between 3D modelling packages and Internet specific presentation formats such as VRML and QTVR. The proposed technique provides some level of interactivity as well as photorealistic landscape representation extended to the horizon, without the need for a complete DEM/DTM, thereby making file sizes manageable and capable of WWW presentation. It also allows for the issues outlined to be tackled in a more efficient manner than by using either 3D modelling or QTVR on their own.
Three dimensional modeling of laterally loaded pile groups resting in sand
Directory of Open Access Journals (Sweden)
Amr Farouk Elhakim
2016-04-01
Full Text Available Many structures often carry lateral loads due to earth pressure, wind, earthquakes, wave action and ship impact. The accurate predictions of the load–displacement response of the pile group as well as the straining actions are needed for a safe and economic design. Most research focused on the behavior of laterally loaded single piles though piles are most frequently used in groups. Soil is modeled as an elastic-perfectly plastic model using the Mohr–Coulomb constitutive model. The three-dimensional Plaxis model is validated using load–displacement results from centrifuge tests of laterally loaded piles embedded in sand. This study utilizes three dimensional finite element modeling to better understand the main parameters that affect the response of laterally loaded pile groups (2 × 2 and 3 × 3 pile configurations including sand relative density, pile spacing (s = 2.5 D, 5 D and 8 D and pile location within the group. The fixity of the pile head affects its load–displacement under lateral loading. Typically, the pile head may be unrestrained (free head as the pile head is allowed to rotate, or restrained (fixed head condition where no pile head rotation is permitted. The analyses were performed for both free and fixed head conditions.
Scrapie prions: a three-dimensional model of an infectious fragment.
Huang, Z; Prusiner, S B; Cohen, F E
1996-01-01
A conformational change seems to represent the major difference between the scrapie prion protein (PrPSc) and its normal cellular isoform (PrPC). We recently proposed a set of four helix bundle models for the three-dimensional structure of PrPC that are consistent with a variety of spectroscopic and genetic data. We report a plausible model for the three-dimensional structure of a biologically important fragment of PrPSc. The model of residues 108-218 was constructed by an approach that combines computational techniques and experimental data. The proposed structures of this fragment of PrPSc display a four-stranded beta-sheet covered on one face by two alpha-helices. Residues implicated in the prion species barrier are found to cluster on the solvent-accessible surface of the beta-sheet of one of the models. This interface could provide a structural template that would assist the conversion of PrPC to PrPSc and hence direct prion propagation. Molecular models of the PrP isoforms should prove very useful in developing structural hypotheses about the process by which PrPC is transformed into PrPSc, the mechanisms by which PrP gene mutations give rise to the inherited human prion diseases, and the species barrier that seems to protect humans from animal prions. It seems likely that PrPC represents a kinetically trapped intermediate in PrP folding.
Directory of Open Access Journals (Sweden)
Canio Hoffarth
2017-03-01
Full Text Available A three-dimensional constitutive model has been developed for modeling orthotropic composites subject to impact loads. It has three distinct components—a deformation model involving elastic and plastic deformations; a damage model; and a failure model. The model is driven by tabular data that is generated either using laboratory tests or via virtual testing. A unidirectional composite—T800/F3900, commonly used in the aerospace industry, is used in the verification and validation tests. While the failure model is under development, these tests indicate that the implementation of the deformation and damage models in a commercial finite element program, LS-DYNA, is efficient, robust and accurate.
Electronic transport on the spatial structure of the protein: Three-dimensional lattice model
International Nuclear Information System (INIS)
Sarmento, R.G.; Frazão, N.F.; Macedo-Filho, A.
2017-01-01
Highlights: • The electronic transport on the structure of the three-dimensional lattice model of the protein is studied. • The signing of the current–voltage is directly affected by permutations of the weak bonds in the structure. • Semiconductor behave of the proteins suggest a potential application in the development of novel biosensors. - Abstract: We report a numerical analysis of the electronic transport in protein chain consisting of thirty-six standard amino acids. The protein chains studied have three-dimensional structure, which can present itself in three distinct conformations and the difference consist in the presence or absence of thirteen hydrogen-bondings. Our theoretical method uses an electronic tight-binding Hamiltonian model, appropriate to describe the protein segments modeled by the amino acid chain. We note that the presence and the permutations between weak bonds in the structure of proteins are directly related to the signing of the current–voltage. Furthermore, the electronic transport depends on the effect of temperature. In addition, we have found a semiconductor behave in the models investigated and it suggest a potential application in the development of novel biosensors for molecular diagnostics.
Electronic transport on the spatial structure of the protein: Three-dimensional lattice model
Energy Technology Data Exchange (ETDEWEB)
Sarmento, R.G. [Departamento de Ciências Biológicas, Universidade Federal do Piauí, 64800-000 Floriano, PI (Brazil); Frazão, N.F. [Centro de Educação e Saúde, Universidade Federal de Campina Grande, 581750-000 Cuité, PB (Brazil); Macedo-Filho, A., E-mail: amfilho@gmail.com [Campus Prof. Antonio Geovanne Alves de Sousa, Universidade Estadual do Piauí, 64260-000 Piripiri, PI (Brazil)
2017-01-30
Highlights: • The electronic transport on the structure of the three-dimensional lattice model of the protein is studied. • The signing of the current–voltage is directly affected by permutations of the weak bonds in the structure. • Semiconductor behave of the proteins suggest a potential application in the development of novel biosensors. - Abstract: We report a numerical analysis of the electronic transport in protein chain consisting of thirty-six standard amino acids. The protein chains studied have three-dimensional structure, which can present itself in three distinct conformations and the difference consist in the presence or absence of thirteen hydrogen-bondings. Our theoretical method uses an electronic tight-binding Hamiltonian model, appropriate to describe the protein segments modeled by the amino acid chain. We note that the presence and the permutations between weak bonds in the structure of proteins are directly related to the signing of the current–voltage. Furthermore, the electronic transport depends on the effect of temperature. In addition, we have found a semiconductor behave in the models investigated and it suggest a potential application in the development of novel biosensors for molecular diagnostics.
Three-dimensional flow structure measurements behind a queue of studied model vehicles
International Nuclear Information System (INIS)
Huang, J.F.; Chan, T.L.; Zhou, Y.
2009-01-01
The three-dimensional flow structures of a queue of studied model vehicles (i.e., one-, two- and three-vehicle cases) were investigated comprehensively in a closed-circuit wind tunnel using particle image velocimetry (PIV) for the typical urban vehicle speeds (i.e., 10, 30 and 50 km/h). In this three-dimensional vehicle wake, a pair of longitudinal vortices is characterized by counter-rotating and moving downstream at relatively low velocity than their surrounding flow. The flow structures of multiple studied model vehicles are dominated by the wake generated from the last studied model vehicle but the preceding studied model vehicle(s) also has/have some minor effects. Cross-sectional turbulence distribution is non-uniform in the far-wake region for all studied cases. The lowest turbulence occurs at the center part of the vehicle wake while high turbulence occurs at its two sides. As such, it may lead to considerable underestimation in turbulence magnitude if the measurement is only taken along the centerline of the vehicle wake.
THREE-DIMENSIONAL GEOFILTRATIONAL MODEL OF THE ROGUN HYDRO POWER PLANT CONSTRUCTION SITE
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Khokhotva Sergey Nikolaevich
2017-05-01
Full Text Available The article deals with technique of creation and results of calculations of the three-dimensional geofiltrational model of the Rogun HPP construction site. When performing works on creation of the Rogun HPP three-dimensional geofiltration model, geological and hydrogeological conditions of the Rogun HPP construction site were analyzed. They showed that the construction site consists mostly of fractured rocks of various weathering degrees. In terms of preservation, four preservation zones were identified in the rock mass. These zones define the features of hydrogeological conditions that have emerged in the area of construction. Calculation results illustrated the absence of seepage areas on the lower slope of dam; this is the indication of normal operation of the dam impervious circuit. The drainage system of the underground hydropower plant has a high efficiency. Operation of the drainage galleries complex leads to a significant reduction of piezometric pressure on roofs of the machine and transformer halls. Above the underground structures a completely drained area is formed. Completed forecast calculations on geofiltration model of the Rogun hydropower plant determine the hydrostatic pressure and piezometric pressure at any point of the modeled area. These data can be used as loads while designing of lining of underground workings.
Three-Dimensional Transient Electromagnetic Modeling Based on Fictitious Wave Domain Methods
Ji, Yanju; Hu, Yanpu; Imamura, Naoto
2017-05-01
Finite-difference time domain (FDTD) methods, which have been widely employed in three-dimensional transient electromagnetic (TEM) modeling, require very small time steps to simulate the electromagnetic fields and this will be time consuming. We present an efficient numerical method for three-dimensional TEM forward modeling. Its key features are based on a correspondence principle between the diffusive and fictitious wave fields. The diffusive Maxwell's equations are transformed and solved in a so-called fictitious wave domain. This scheme allows larger time steps than conventional FDTD methods, allows including air layers, and allows simulating topography. The need for initial field calculations is avoided by including an electric current source in the governing equations. This also avoids a traditional assumption of a flat earth surface in TEM modeling. We test the accuracy of the electromagnetic fields' responses using our method with the spectral differential difference (SLDM) solutions. The results show good agreement even under the existence of air layers and topography in the model.
Energy Technology Data Exchange (ETDEWEB)
Thorne, P.D.; Chamness, M.A.; Vermeul, V.R.; Macdonald, Q.C.; Schubert, S.E.
1994-11-01
This report documents work conducted during the fiscal year 1994 to development an improved three-dimensional conceptual model of ground-water flow in the unconfined aquifer system across the Hanford Site Ground-Water Surveillance Project, which is managed by Pacific Northwest Laboratory. The main objective of the ongoing effort to develop an improved conceptual model of ground-water flow is to provide the basis for improved numerical report models that will be capable of accurately predicting the movement of radioactive and chemical contaminant plumes in the aquifer beneath Hanford. More accurate ground-water flow models will also be useful in assessing the impacts of changes in facilities and operations. For example, decreasing volumes of operational waste-water discharge are resulting in a declining water table in parts of the unconfined aquifer. In addition to supporting numerical modeling, the conceptual model also provides a qualitative understanding of the movement of ground water and contaminants in the aquifer.
A three-dimensional meso-macroscopic model for Li-Ion intercalation batteries
Allu, S.; Kalnaus, S.; Simunovic, S.; Nanda, J.; Turner, J. A.; Pannala, S.
2016-09-01
In this paper we present a three-dimensional computational formulation for electrode-electrolyte-electrode system of Li-Ion batteries. The physical consistency between electrical, thermal and chemical equations is enforced at each time increment by driving the residual of the resulting coupled system of nonlinear equations to zero. The formulation utilizes a rigorous volume averaging approach typical of multiphase formulations used in other fields and recently extended to modeling of supercapacitors [1]. Unlike existing battery modeling methods which use segregated solution of conservation equations and idealized geometries, our unified approach can model arbitrary battery and electrode configurations. The consistency of multi-physics solution also allows for consideration of a wide array of initial conditions and load cases. The formulation accounts for spatio-temporal variations of material and state properties such as electrode/void volume fractions and anisotropic conductivities. The governing differential equations are discretized using the finite element method and solved using a nonlinearly consistent approach that provides robust stability and convergence. The new formulation was validated for standard Li-ion cells and compared against experiments. Its scope and ability to capture spatio-temporal variations of potential and lithium distribution is demonstrated on a prototypical three-dimensional electrode problem.
Three-dimensional plasma simulation models and their application to magnetically confined plasmas
International Nuclear Information System (INIS)
Okuda, H.
1977-03-01
Three-dimensional plasma simulation models using particles have been described and applied to the various microscopic processes in a plasma in a magnetic field. The model makes use of the hybrid approach using eigenfunction expansion in one direction and multipole expansion on a two-dimensional spatial grid introduced in the cross section of a plasma. The models for cylindrical and toroidal systems correctly reproduce the expected fluctuation spectrum in thermal equilibrium. Application to the study of anomalous plasma diffusion due to collisionless drift instabilities in a cylindrical plasma is shown. Some considerations are given as to how to construct a quasi-neutral particle simulation model and particle-fluid hybrid plasma model which eliminate the high frequency oscillations associated with the electrons
Computer-aided-design-model-assisted absolute three-dimensional shape measurement.
Li, Beiwen; Bell, Tyler; Zhang, Song
2017-08-20
Conventional three-dimensional (3D) shape measurement methods are typically generic to all types of objects. Yet, for many measurement conditions, such a level of generality is inessential when having the preknowledge of the object geometry. This paper introduces a novel adaptive algorithm for absolute 3D shape measurement with the assistance of the object computer-aided-design (CAD) model. The proposed algorithm includes the following major steps: (1) export the 3D point cloud data from the CAD model; (2) transform the CAD model into the camera perspective; (3) obtain a wrapped phase map from three phase-shifted fringe images; and (4) retrieve absolute phase and 3D geometry assisted by the CAD model. We demonstrate that if object CAD models are available, such an algorithm is efficient in recovering absolute 3D geometries of both simple and complex objects with only three phase-shifted fringe images.
FITTING A THREE DIMENSIONAL PEM FUEL CELL MODEL TO MEASUREMENTS BY TUNING THE POROSITY AND
DEFF Research Database (Denmark)
Bang, Mads; Odgaard, Madeleine; Condra, Thomas Joseph
2004-01-01
the distribution of current density and further how thisaffects the polarization curve.The porosity and conductivity of the catalyst layer are some ofthe most difficult parameters to measure, estimate and especiallycontrol. Yet the proposed model shows how these two parameterscan have significant influence...... on the performance of the fuel cell.The two parameters are shown to be key elements in adjusting thethree-dimensional model to fit measured polarization curves.Results from the proposed model are compared to single cellmeasurements on a test MEA from IRD Fuel Cells.......A three-dimensional, computational fluid dynamics (CFD) model of a PEM fuel cell is presented. The model consists ofstraight channels, porous gas diffusion layers, porous catalystlayers and a membrane. In this computational domain, most ofthe transport phenomena which govern the performance of the...
Three-dimensional hydrological and thermal property models of Yucca Mountain, Nevada
International Nuclear Information System (INIS)
Rautman, C.A.; McKenna, S.A.
1997-11-01
This report describes the creation of three-dimensional numerical models of selected rock-matrix properties for the region of the potential high-level nuclear waste repository site at Yucca Mountain, which is located in southern Nevada. The models have been generated for a majority of the unsaturated and shallow saturated zone within an area referred to within the Yucca Mountain Site Characterization project as the site area. They comprise a number of material properties of importance both to detailed process-level modeling activities and to more summary-style performance assessment modeling. The material properties within these models are both spatially variable (heterogeneous) and spatially correlated, as the rocks are understood from data obtained from site-characterization drill holes widely scattered across the site area
Three-Dimensional Assembly Tolerance Analysis Based on the Jacobian-Torsor Statistical Model
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Peng Heping
2017-01-01
Full Text Available The unified Jacobian-Torsor model has been developed for deterministic (worst case tolerance analysis. This paper presents a comprehensive model for performing statistical tolerance analysis by integrating the unified Jacobian-Torsor model and Monte Carlo simulation. In this model, an assembly is sub-divided into surfaces, the Small Displacements Torsor (SDT parameters are used to express the relative position between any two surfaces of the assembly. Then, 3D dimension-chain can be created by using a surface graph of the assembly and the unified Jacobian-Torsor model is developed based on the effect of each functional element on the whole functional requirements of products. Finally, Monte Carlo simulation is implemented for the statistical tolerance analysis. A numerical example is given to demonstrate the capability of the proposed method in handling three-dimensional assembly tolerance analysis.
Kasoju, Aruna; Narasu, M Lakshmi; Muvva, Charuvaka; Subbarao, Bathula Vv
2012-01-01
Aflatoxins are polyketide-derived secondary metabolites produced by Aspergillus spp. The toxic effects of aflatoxins have adverse consequences for human health and agricultural economics. The aflR gene, a regulatory gene for aflatoxin biosynthesis, encodes a protein containing a zinc-finger DNA-binding motif. AFLR-Protein three-dimensional model was generated using Robetta server. The modeled AFLR-Protein was further optimization and validation using Rampage. In the simulations, we monitored the backbone atoms and the C-α-helix of the modeled protein. The low RMSD and the simulation time indicate that, as expected, the 3D structural model of AFLR-protein represents a stable folding conformation. This study paves the way for generating computer molecular models for proteins whose crystal structures are not available and which would aid in detailed molecular mechanism of inhibition of aflatoxin.
Three-dimensional hydrological and thermal property models of Yucca Mountain, Nevada
Energy Technology Data Exchange (ETDEWEB)
Rautman, C.A.; McKenna, S.A. [Sandia National Labs., Albuquerque, NM (United States). Geohydrology Dept.
1997-11-01
This report describes the creation of three-dimensional numerical models of selected rock-matrix properties for the region of the potential high-level nuclear waste repository site at Yucca Mountain, which is located in southern Nevada. The models have been generated for a majority of the unsaturated and shallow saturated zone within an area referred to within the Yucca Mountain Site Characterization project as the site area. They comprise a number of material properties of importance both to detailed process-level modeling activities and to more summary-style performance assessment modeling. The material properties within these models are both spatially variable (heterogeneous) and spatially correlated, as the rocks are understood from data obtained from site-characterization drill holes widely scattered across the site area.
Construction of a Three-Dimensional in vitro skin model on polycaprolactone fibers.
Liu, Qi; Zhang, Ru-Zhi; Xu, Bin
2017-05-16
To observe the morphological characteristics and the biological properties of human epidermal cells when cultured at an air-liquid interface in polycaprolactone (PCL) fibers as a three-dimensional scaffold for tissue engineering. In this study, the melanocytes and keratinocytes were obtained from human scalp skin, seeded onto a PCL film, and cocultured for 2 weeks to construct a three-dimensional (3D) skin model. The cells were then characterized by hematoxylin and eosin (H&E) staining, by immunohistochemical staining with antibodies to cytokeratin 15 (CK15), Ki-67, CD34, CD200 and HMB45 and by transmission electron microscopy. Keratinocytes and melanocytes grew well in the co-culture system. Hematoxylin and eosin staining revealed that the cells adhered to the PCLfiber scaffold well, the keratinocyte layer became a multilayered concentric structure and the surface became distinctly keratinized at the air-liquid interface. Immunohistochemical analyses exhibited a scattered distribution of cells expressing CK15, CD34, CD200, Ki-67 and/or HMB45. Transmission electron microscopy revealed that the keratinocytes contained a number of keratin fibrils and membrane-coated granules. The PCL scaffold has excellent adhesiveness and biocompatibility with human epidermal cells, and is suitable for constructing 3D skin models for tissue engineering in the future.
Three-Dimensional Numerical Modeling of Macrosegregation in Continuously Cast Billets
Directory of Open Access Journals (Sweden)
Qipeng Dong
2017-06-01
Full Text Available Macrosegregation, serving as a major defect in billets, can severely degrade material homogeneity. Better understanding of the physical characteristics of macrosegregation through numerical simulation could significantly contribute to the segregation control. The main purpose of this study was to predict macrosegregation in continuously cast billets with a newly developed three-dimensional macrosegregation model. The fluid flow, solidification, and solute transport in the entire billet region were solved and analyzed. Flow patterns, revealing a typical melt recirculation at the upper region of mold and thermosolutal convection at the secondary cooling zone, significantly affect the solidification and solute distribution. The solute redistribution occurring with thermosolutal convection at the solidification front contributes significantly to continued macrosegregation as solidification proceeds. The results of this study show that the equilibrium partition coefficient is mostly responsible for the magnitude of macrosegregation, while comparison between solute P and S indicated that diffusion coefficients also have some amount of influence. Typical macrosegregation patterns containing a positively segregated peak at the centerline and negatively segregated minima at either side were obtained via the proposed three-dimensional macrosegregation model, which validated by the measured surface temperatures and segregation degree.
Three-dimensional linear fracture mechanics analysis by a displacement-hybrid finite-element model
International Nuclear Information System (INIS)
Atluri, S.N.; Kathiresan, K.; Kobayashi, A.S.
1975-01-01
This paper deals with a finite-element procedures for the calculation of modes I, II and III stress intensity factors, which vary, along an arbitrarily curved three-dimensional crack front in a structural component. The finite-element model is based on a modified variational principle of potential energy with relaxed continuity requirements for displacements at the inter-element boundary. The variational principle is a three-field principle, with the arbitrary interior displacements for the element, interelement boundary displacements, and element boundary tractions as variables. The unknowns in the final algebraic system of equations, in the present displacement hybrid finite element model, are the nodal displacements and the three elastic stress intensity factors. Special elements, which contain proper square root and inverse square root crack front variations in displacements and stresses, respectively, are used in a fixed region near the crack front. Interelement displacement compatibility is satisfied by assuming an independent interelement boundary displacement field, and using a Lagrange multiplier technique to enforce such interelement compatibility. These Lagrangean multipliers, which are physically the boundary tractions, are assumed from an equilibrated stress field derived from three-dimensional Beltrami (or Maxwell-Morera) stress functions that are complete. However, considerable care should be exercised in the use of these stress functions such that the stresses produced by any of these stress function components are not linearly dependent
An three-dimensional imaging algorithm based on the radiation model of electric dipole
International Nuclear Information System (INIS)
Tian Bo; Zhong Weijun; Tong Chuangming
2011-01-01
A three-dimensional imaging algorithm based on the radiation model of dipole (DBP) is presented. On the foundation of researching the principle of the back projection (BP) algorithm, the relationship between the near field imaging model and far field imaging model is analyzed based on the scattering model. Firstly, the far field sampling data is transferred to the near field sampling data through applying the radiation theory of dipole. Then the dealt sampling data was projected to the imaging region to obtain the images of targets. The capability of the new algorithm to detect targets is verified by using finite-difference time-domain method (FDTD), and the coupling effect for imaging is analyzed. (authors)
Three-dimensional models of conventional and vertical junction laser-photovoltaic energy converters
Heinbockel, John H.; Walker, Gilbert H.
1988-01-01
Three-dimensional models of both conventional planar junction and vertical junction photovoltaic energy converters have been constructed. The models are a set of linear partial differential equations and take into account many photoconverter design parameters. The model is applied to Si photoconverters; however, the model may be used with other semiconductors. When used with a Nd laser, the conversion efficiency of the Si vertical junction photoconverter is 47 percent, whereas the efficiency for the conventional planar Si photoconverter is only 17 percent. A parametric study of the Si vertical junction photoconverter is then done in order to describe the optimum converter for use with the 1.06-micron Nd laser. The efficiency of this optimized vertical junction converter is 44 percent at 1 kW/sq cm.
Analytical model for three-dimensional Mercedes-Benz water molecules
Urbic, T.
2013-01-01
We developed a statistical model which describes the thermal and volumetric properties of water-like molecules. A molecule is presented as a three-dimensional sphere with four hydrogen-bonding arms. Each water molecule interacts with its neighboring waters through a van der Waals interaction and an orientation-dependent hydrogen-bonding interaction. This model, which is largely analytical, is a variant of a model developed before for a two-dimensional Mercedes-Benz model of water. We explored properties such as molar volume, density, heat capacity, thermal expansion coefficient, and isothermal compressibility as a function of temperature and pressure. We found that the volumetric and thermal properties follow the same trends with temperature as in real water and are in good general agreement with Monte Carlo simulations, including the density anomaly, the minimum in the isothermal compressibility, and the decreased number of hydrogen bonds upon increasing the temperature. PMID:23005100
Three-dimensional ray-tracing model for the study of advanced refractive errors in keratoconus.
Schedin, Staffan; Hallberg, Per; Behndig, Anders
2016-01-20
We propose a numerical three-dimensional (3D) ray-tracing model for the analysis of advanced corneal refractive errors. The 3D modeling was based on measured corneal elevation data by means of Scheimpflug photography. A mathematical description of the measured corneal surfaces from a keratoconus (KC) patient was used for the 3D ray tracing, based on Snell's law of refraction. A model of a commercial intraocular lens (IOL) was included in the analysis. By modifying the posterior IOL surface, it was shown that the imaging quality could be significantly improved. The RMS values were reduced by approximately 50% close to the retina, both for on- and off-axis geometries. The 3D ray-tracing model can constitute a basis for simulation of customized IOLs that are able to correct the advanced, irregular refractive errors in KC.
Analytical model for three-dimensional Mercedes-Benz water molecules.
Urbic, T
2012-06-01
We developed a statistical model which describes the thermal and volumetric properties of water-like molecules. A molecule is presented as a three-dimensional sphere with four hydrogen-bonding arms. Each water molecule interacts with its neighboring waters through a van der Waals interaction and an orientation-dependent hydrogen-bonding interaction. This model, which is largely analytical, is a variant of a model developed before for a two-dimensional Mercedes-Benz model of water. We explored properties such as molar volume, density, heat capacity, thermal expansion coefficient, and isothermal compressibility as a function of temperature and pressure. We found that the volumetric and thermal properties follow the same trends with temperature as in real water and are in good general agreement with Monte Carlo simulations, including the density anomaly, the minimum in the isothermal compressibility, and the decreased number of hydrogen bonds upon increasing the temperature.
An analysis of three dimensional diffusion in a representative arterial wall mass transport model.
Denny, William J; O'Connell, Barry M; Milroy, John; Walsh, Michael T
2013-05-01
The development and use of drug eluting stents has brought about significant improvements in reducing in-stent restenosis, however, their long term presence in the artery is still under examination due to restenosis reoccurring. Current studies focus mainly on stent design, coatings and deployment techniques but few studies address the issue of the physics of three dimensional mass transport in the artery wall. There is a dearth of adequate validated numerical mass transport models that simulate the physics of diffusion dominated drug transport in the artery wall whilst under compression. A novel experimental setup used in a previous study was adapted and an expansion of that research was carried out to validate the physics of three dimensional diffusive mass transport into a compressed porous media. This study developed a more sensitive method for measuring the concentration of the species of interest. It revalidated mass transport in the radial direction and presented results which highlight the need for an evaluation of the governing equation for transient diffusive mass transport in a porous media, in its current form, to be carried out.
Frampton, J. P.; Hynd, M. R.; Williams, J. C.; Shuler, M. L.; Shain, W.
2007-12-01
One limitation to the use of neuroprosthestic devices for chronic application, in the treatment of disease, is the reactive cell responses that occur surrounding the device after insertion. These cell and tissue responses result in increases in device impedance and failure of the device to interact with target populations of neurons. However, few tools are available to assess which components of the reactive response contribute most to changes in tissue impedance. An in vitro culture system has been developed that is capable of assessing individual components of the reactive response. The system utilizes alginate cell encapsulation to construct three-dimensional architectures that approach the cell densities found in rat cortex. The system was constructed around neuroNexus acute probes with on-board circuitry capable of monitoring the electrical properties of the surrounding tissue. This study demonstrates the utility of the system by demonstrating that differences in cell density within the three-dimensional alginate constructs result in differences in resistance and capacitance as measured by electrochemical impedance spectroscopy. We propose that this system can be used to model components of the reactive responses in brain tissue, and that the measurements recorded in vitro are comparable to measurements recorded in vivo.
Mechanism of drag reduction on a three-dimensional model vehicle using a passive control device
Yi, Wook; Sagong, Woong; Choi, Haecheon
2007-11-01
It has been well known that the boat-tail device reduces drag on a three-dimensional vehicle. However, its detailed mechanism is not clearly known yet. To understand this mechanism, we conduct an experiment for flow over a three-dimensional model vehicle in ground proximity. We consider various lengths (l/H = 0.1 ˜0.5) and slant angles (θ=0^o ˜40^o) of the boat tail, and conduct velocity measurements near the boat tail and oil visualizations on the boat-tail surface. We find that the slant angle is an important parameter for drag reduction. The maximum drag reduction occurs at θ=12.5^o, 15^o and 15^o for l/H = 0.1, 0.3 and 0.5, respectively, and the amounts of maximum drag reduction are 20, 41 and 45%. For the case of l/H = 0.3, separation starts to occur from θ= 6^o at the leading edge of the boat tail. This separated flow reattaches on the boat-tail surface and forms a small secondary separation bubble, which provides strong near-wall momentum and delays main separation down to the trailing edge of boat tail. The size of secondary separation bubble increases with increasing θ. At θ>16^o, main separation occurs at the leading edge of boat tail, and drag increases from the minimum value and reaches that of no control at large θ's.
Culture of three-dimensional tissue model and its application in bystander-effect research
International Nuclear Information System (INIS)
Wu Ruqun; Xu An; Wu Lijun; Hu Burong
2012-01-01
Compared with the cultured monolayer (2D) cells, three-dimensional (3D) tissue could be more similar to the environment in vivo including the physical support, chemical factors, cell-cell and cell-matrix interaction and so on. With the development of three-dimensional cell culture techniques (TDCC), 3D tissue is widely used in the areas of bystander effect research. This review focuses on introducing the TDCC method and its application in bystander-effect research. First, the development process of 3D tissue culture method was introduced. Secondly, the induction of radiation induced bystander effects both in 2D cell and 3D tissue and its mechanisms were reviewed. Finally, because heavy ion (carbon ion beam) has been developed as a useful tool to cure solid cancer, and the 3D tissue model is an ideal material to study the damages on body after being irradiated and to understand the underlying mechanisms, future study about heavy ion radiation inducing bystander effect in 3D tissue was discussed. (authors)
Insulin as a model to teach three-dimensional structure of proteins
Directory of Open Access Journals (Sweden)
João Batista Teixeira da Rocha
2018-02-01
Proteins are the most ubiquitous macromolecules found in the living cells and have innumerous physiological functions. Therefore, it is fundamental to build a solid knowledge about the proteins three dimensional structure to better understand the living state. The hierarchical structure of proteins is usually studied in the undergraduate discipline of Biochemistry. Here we described pedagogical interventions designed to increase the preservice teacher chemistry students’ knowledge about protein structure. The activities were made using alternative and cheap materials to encourage the application of these simple methodologies by the future teachers in the secondary school. From the primary structure of insulin chains, students had to construct a three-dimensional structure of insulin. After the activities, the students highlighted an improvement of their previous knowledge about proteins structure. The construction of a tridimensional model together with other activities seems to be an efficient way to promote the learning about the structure of proteins to undergraduate students. The methodology used was inexpensiveness and simple and it can be used both in the university and in the high-school.
Energy Technology Data Exchange (ETDEWEB)
Usmanov, Arcadi V.; Matthaeus, William H. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Goldstein, Melvyn L., E-mail: arcadi.usmanov@nasa.gov [Code 672, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
2014-06-10
We have developed a three-fluid, three-dimensional magnetohydrodynamic solar wind model that incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating. The solar wind plasma is described as a system of co-moving solar wind protons, electrons, and interstellar pickup protons, with separate energy equations for each species. Numerical steady-state solutions of Reynolds-averaged solar wind equations coupled with turbulence transport equations for turbulence energy, cross helicity, and correlation length are obtained by the time relaxation method in the corotating with the Sun frame of reference in the region from 0.3 to 100 AU (but still inside the termination shock). The model equations include the effects of electron heat conduction, Coulomb collisions, photoionization of interstellar hydrogen atoms and their charge exchange with the solar wind protons, turbulence energy generation by pickup protons, and turbulent heating of solar wind protons and electrons. The turbulence transport model is based on the Reynolds decomposition and turbulence phenomenologies that describe the conversion of fluctuation energy into heat due to a turbulent cascade. In addition to using separate energy equations for the solar wind protons and electrons, a significant improvement over our previous work is that the turbulence model now uses an eddy viscosity approximation for the Reynolds stress tensor and the mean turbulent electric field. The approximation allows the turbulence model to account for driving of turbulence by large-scale velocity gradients. Using either a dipole approximation for the solar magnetic field or synoptic solar magnetograms from the Wilcox Solar Observatory for assigning boundary conditions at the coronal base, we apply the model to study the global structure of the solar wind and its three-dimensional properties, including embedded turbulence, heating, and acceleration throughout the heliosphere. The model results are
Conversion of the Bryan Mound geological site characterization reports to a three-dimensional model.
Energy Technology Data Exchange (ETDEWEB)
Stein, Joshua S.; Rautman, Christopher Arthur
2005-04-01
The Bryan Mound salt dome, located near Freeport, Texas, is home to one of four underground crude oil-storage facilities managed by the U. S. Department of Energy Strategic Petroleum Reserve (SPR) Program. Sandia National Laboratories, as the geotechnical advisor to the SPR, conducts site-characterization investigations and other longer-term geotechnical and engineering studies in support of the program. This report describes the conversion of two-dimensional geologic interpretations of the Bryan Mound site into three-dimensional geologic models. The new models include the geometry of the salt dome, the surrounding sedimentary units, mapped faults, and the 20 oil-storage caverns at the site. This work provides an internally consistent geologic model of the Bryan Mound site that can be used in support of future work.
An eddy-current model for three-dimensional nondestructive evaluation of advanced composites
Sabbagh, Harold A.; Murphy, R. Kim; Sabbagh, Elias H.
2015-03-01
We have developed a rigorous electromagnetic model and an inversion algorithm for the three-dimensional NDE of advanced composite materials. This approach extends Victor Technologies' work in eddy-current NDE of conventional metals, and allows one to determine in localized regions the fiber-resin ratio in graphite-epoxy, and to determine those anomalies, e.g., delaminations, broken fibers, moisture content, etc., that can be reconstructed by our inversion method. In developing the model, we apply rigorous electromagnetic theory to determine a Green's function for a slab of anisotropic composite material, and then determine the integral relations for the forward and inverse problems using the Green's function. We will give examples of the solution of forward problems using this model.
Charafi, My. M.; Sadok, A.; Kamal, A.; Menai, A.
A quasi-three-dimensional mathematical model has been developed to study the morphological processes based on equilibrium sediment transport method. The flow velocities are computed by a two-dimensional horizontal depth-averaged flow model (H2D) in combination with logarithmic velocity profiles. The transport of sediment particles by a flow water has been considered in the form of bed load and suspended load. The bed load transport rate is defined as the transport of particles by rolling and saltating along the bed surface and is given by the Van Rijn relationship (1987). The equilibrium suspended load transport is described in terms of an equilibrium sediment concentration profile (ce) and a logarithmic velocity (u). Based on the equilibrium transport, the bed change rate is given by integration of the sediment mass-balance equation. The model results have been compared with a Van Rijn results (equilibrium approach) and good agreement has been found.
Xiang, G.L.; Vire, A.; Pavlidis, D.; Pain, C.
2015-01-01
A three-dimensional fracture model developed in the context of the combined finite-discrete element method is incorporated into a two-way fluid-solid coupling model. The fracture model is capable of simulating the whole fracturing process. It includes pre-peak hardening deformation, post-peak strain
A Web-based Visualization System for Three Dimensional Geological Model using Open GIS
Nemoto, T.; Masumoto, S.; Nonogaki, S.
2017-12-01
A three dimensional geological model is an important information in various fields such as environmental assessment, urban planning, resource development, waste management and disaster mitigation. In this study, we have developed a web-based visualization system for 3D geological model using free and open source software. The system has been successfully implemented by integrating web mapping engine MapServer and geographic information system GRASS. MapServer plays a role of mapping horizontal cross sections of 3D geological model and a topographic map. GRASS provides the core components for management, analysis and image processing of the geological model. Online access to GRASS functions has been enabled using PyWPS that is an implementation of WPS (Web Processing Service) Open Geospatial Consortium (OGC) standard. The system has two main functions. Two dimensional visualization function allows users to generate horizontal and vertical cross sections of 3D geological model. These images are delivered via WMS (Web Map Service) and WPS OGC standards. Horizontal cross sections are overlaid on the topographic map. A vertical cross section is generated by clicking a start point and an end point on the map. Three dimensional visualization function allows users to visualize geological boundary surfaces and a panel diagram. The user can visualize them from various angles by mouse operation. WebGL is utilized for 3D visualization. WebGL is a web technology that brings hardware-accelerated 3D graphics to the browser without installing additional software. The geological boundary surfaces can be downloaded to incorporate the geologic structure in a design on CAD and model for various simulations. This study was supported by JSPS KAKENHI Grant Number JP16K00158.
International Nuclear Information System (INIS)
Thernisien, A.
2011-01-01
The graduated cylindrical shell (GCS) model developed by Thernisien et al. has been used with the goal of studying the three-dimensional morphology, position, and kinematics of coronal mass ejections observed by coronagraphs. These studies focused more on the results rather than the details of the model itself. As more researchers begin to use the model, it becomes necessary to provide a deeper discussion on how it is derived, which is the purpose of this paper. The model is built using the following features and constraints: (1) the legs are conical, (2) the front is pseudo-circular, (3) the cross section is circular, and (4) it expands in a self-similar way. We derive the equation of the model from these constraints. We also show that the ice-cream cone model is a limit of the GCS when the two legs overlap completely. Finally, we provide formulae for the calculation of various geometrical dimensions, such as angular width and aspect ratio, as well as the pseudo-code that is used for its computer implementation.
Rashev, Peter Z; Bowes, Kenneth L; Mintchev, Martin P
2002-12-01
Three-dimensional (3-D) object-oriented models are needed for optimizing gastric electrical stimulation by performing virtual computer experiments. The aim of the study was to create a 3-D object-oriented electromechanical model of the stomach in vivo for the purpose of microprocessor controlled functional stimulation. The stomach was modeled using coaxial truncated conoids as objects. The strength of an external stimulating electric field generated by circumferentially implanted wire electrodes is related to artificial neurogenic and myogenic control of smooth muscle depolarization and contraction. Variation of the field strength modulates the frequency and concentration of acetylcholine release, as well as the transmembrane voltage of the muscle cells. Mechanical response of the stimulated tissue was quantified by two parametric functions of the electric field strength representing the relative contractile force and geometrical displacement of the gastric surface. Data from previously conducted canine experiments were used to test the validity of the model. The model was applied to simulate contractions with different positions, orientation and number of the circumferentially implanted stimulating electrodes. The model combined most of the existing theoretical and experimental findings concerning functional gastric stimulation and can be utilized as a flexible tool for virtual medical tests involving external high-frequency (50 Hz) neural stimulation.
Three-dimensional geologic model of the southeastern Espanola Basin, Santa Fe County, New Mexico
Pantea, Michael P.; Hudson, Mark R.; Grauch, V.J.S.; Minor, Scott A.
2011-01-01
This multimedia model and report show and describe digital three-dimensional faulted surfaces and volumes of lithologic units that confine and constrain the basin-fill aquifers within the Espanola Basin of north-central New Mexico. These aquifers are the primary groundwater resource for the cities of Santa Fe and Espanola, six Pueblo nations, and the surrounding areas. The model presented in this report is a synthesis of geologic information that includes (1) aeromagnetic and gravity data and seismic cross sections; (2) lithologic descriptions, interpretations, and geophysical logs from selected drill holes; (3) geologic maps, geologic cross sections, and interpretations; and (4) mapped faults and interpreted faults from geophysical data. Modeled faults individually or collectively affect the continuity of the rocks that contain the basin aquifers; they also help define the form of this rift basin. Structure, trend, and dip data not previously published were added; these structures are derived from interpretations of geophysical information and recent field observations. Where possible, data were compared and validated and reflect the complex relations of structures in this part of the Rio Grande rift. This interactive geologic framework model can be used as a tool to visually explore and study geologic structures within the Espanola Basin, to show the connectivity of geologic units of high and low permeability between and across faults, and to show approximate dips of the lithologic units. The viewing software can be used to display other data and information, such as drill-hole data, within this geologic framework model in three-dimensional space.
Geostatistical three-dimensional modeling of oolite shoals, St. Louis Limestone, southwest Kansas
Qi, L.; Carr, T.R.; Goldstein, R.H.
2007-01-01
In the Hugoton embayment of southwestern Kansas, reservoirs composed of relatively thin (oil. The geometry and distribution of oolitic deposits control the heterogeneity of the reservoirs, resulting in exploration challenges and relatively low recovery. Geostatistical three-dimensional (3-D) models were constructed to quantify the geometry and spatial distribution of oolitic reservoirs, and the continuity of flow units within Big Bow and Sand Arroyo Creek fields. Lithofacies in uncored wells were predicted from digital logs using a neural network. The tilting effect from the Laramide orogeny was removed to construct restored structural surfaces at the time of deposition. Well data and structural maps were integrated to build 3-D models of oolitic reservoirs using stochastic simulations with geometry data. Three-dimensional models provide insights into the distribution, the external and internal geometry of oolitic deposits, and the sedimentologic processes that generated reservoir intervals. The structural highs and general structural trend had a significant impact on the distribution and orientation of the oolitic complexes. The depositional pattern and connectivity analysis suggest an overall aggradation of shallow-marine deposits during pulses of relative sea level rise followed by deepening near the top of the St. Louis Limestone. Cemented oolitic deposits were modeled as barriers and baffles and tend to concentrate at the edge of oolitic complexes. Spatial distribution of porous oolitic deposits controls the internal geometry of rock properties. Integrated geostatistical modeling methods can be applicable to other complex carbonate or siliciclastic reservoirs in shallow-marine settings. Copyright ?? 2007. The American Association of Petroleum Geologists. All rights reserved.
A three-dimensional cellular automaton model for dendritic growth in multi-component alloys
International Nuclear Information System (INIS)
Zhang Xianfei; Zhao, Jiuzhou; Jiang, Hongxiang; Zhu, Mingfang
2012-01-01
A three-dimensional (3-D) cellular automaton model for dendritic growth in multi-component alloys is developed. The velocity of advance of the solid/liquid (S/L) interface is calculated using the solute conservation relationship at the S/L interface. The effect of interactions between the alloying elements on the diffusion coefficient of solutes in the solid and liquid phases are considered. The model is first validated by comparing with the theoretical predictions for binary and ternary alloys, and then applied to simulate the solidification process of Al–Cu–Mg alloys by a coupling of thermodynamic and kinetic calculations. The numerical results obtained show both the free dendrite growth process as well as the directional solidification process. The calculated secondary dendrite arm spacing in the directionally solidified Al–Cu–Mg alloy is in good agreement with the experimental results. The effect of interactions between the various alloying elements on dendritic growth is discussed.
Sabbagh, Harold A.; Murphy, R. Kim; Sabbagh, Elias H.
2016-02-01
In past work we have developed a rigorous electromagnetic model and an inversion algorithm for the three-dimensional NDE of advanced composite materials. This approach extends Victor Technologies' work in eddy-current NDE of conventional metals, and allows one to determine in localized regions the fiber-resin ratio in graphite-epoxy, and to determine those anomalies, e.g., delaminations, broken fibers, moisture content, etc., that can be reconstructed by our inversion method. In developing the model, we applied rigorous electromagnetic theory to determine a Green's function for a slab of anisotropic composite material, and then determine the integral relations for the forward and inverse problems using the Green's function. In addition, we have given examples of the solution of forward and inverse problems using these algorithms.
Coarse-graining intermittent intracellular transport: Two- and three-dimensional models
Lawley, Sean D.; Tuft, Marie; Brooks, Heather A.
2015-10-01
Viruses and other cellular cargo that lack locomotion must rely on diffusion and cellular transport systems to navigate through a biological cell. Indeed, advances in single particle tracking have revealed that viral motion alternates between (a) diffusion in the cytoplasm and (b) active transport along microtubules. This intermittency makes quantitative analysis of trajectories difficult. Therefore, the purpose of this paper is to construct mathematical methods to approximate intermittent dynamics by effective stochastic differential equations. The coarse-graining method that we develop is more accurate than existing techniques and applicable to a wide range of intermittent transport models. In particular, we apply our method to two- and three-dimensional cell geometries (disk, sphere, and cylinder) and demonstrate its accuracy. In addition to these specific applications, we also explain our method in full generality for use on future intermittent models.
A new method for three-dimensional laparoscopic ultrasound model reconstruction
DEFF Research Database (Denmark)
Fristrup, C W; Pless, T; Durup, J
2004-01-01
was to perform a volumetric test and a clinical feasibility test of a new 3D method using standard laparoscopic ultrasound equipment. METHODS: Three-dimensional models were reconstructed from a series of two-dimensional ultrasound images using either electromagnetic tracking or a new 3D method. The volumetric...... accuracy of the new method was tested ex vivo, and the clinical feasibility was tested on a small series of patients. RESULTS: Both electromagnetic tracked reconstructions and the new 3D method gave good volumetric information with no significant difference. Clinical use of the new 3D method showed...... accurate models comparable to findings at surgery and pathology. CONCLUSIONS: The use of the new 3D method is technically feasible, and its volumetrically, accurate compared to 3D with electromagnetic tracking....
Gauge structure, anomalies and mass generation in a three dimensional thirring model
International Nuclear Information System (INIS)
Gomes, M.; Mendes, R.S.; Ribeiro, R.F.; Silva, A.J. da.
1990-05-01
We consider a three dimensional model of spinor fields with a Thirring like, quadrilinear self interaction. Using either two or four component Dirac spinors, we prove that the 1/N expansion for the model is renormalizable if a gauge structure to select physical quantities is introduced. For certain values of the coupling the leading 1/N approximation exihibits bound state poles. Dynamical breaking of parity or chiral symmetry is shown to occur as a cooperative effect of different orders of 1/N, if N is smaller than the critical value N c = 128 / x 2 D' , where D is two or four depending on wether the fermion field has two or four components. (author) [pt
Chiral spin liquids at finite temperature in a three-dimensional Kitaev model
Kato, Yasuyuki; Kamiya, Yoshitomo; Nasu, Joji; Motome, Yukitoshi
2017-11-01
Chiral spin liquids (CSLs) in three dimensions and thermal phase transitions to paramagnet are studied by unbiased Monte Carlo simulations. For an extension of the Kitaev model to a three-dimensional tricoordinate network dubbed the hypernonagon lattice, we derive low-energy effective models in two different anisotropic limits. We show that the effective interactions between the emergent Z2 degrees of freedom called fluxes are unfrustrated in one limit, while highly frustrated in the other. In both cases, we find a first-order phase transition to the CSL, where both time-reversal and parity symmetries are spontaneously broken. In the frustrated case, however, the CSL state is highly exotic—the flux configuration is subextensively degenerate while showing a directional order with broken C3 rotational symmetry. Our results provide two contrasting archetypes of CSLs in three dimensions, both of which allow approximation-free simulation for investigating the thermodynamics.
The simulation of the transport of aircraft emissions by a three-dimensional global model
Directory of Open Access Journals (Sweden)
G. J. M. Velders
1994-04-01
Full Text Available A three-dimensional off-line tracer transport model coupled to the ECMWF analyses has been used to study the transport of trace gases in the atmosphere. The model gives a reasonable description of their general transport in the atmosphere. The simulation of the transport of aircraft emissions (as NOx has been studied as well as the transport of passive tracers injected at different altitudes in the North Atlantic flight corridor. A large zonal variation in the NOx concentrations as well as large seasonal and yearly variations was found. The altitude of the flight corridor influences the amount of tracers transported into the troposphere and stratosphere to a great extent.
Pushing the limits of Monte Carlo simulations for the three-dimensional Ising model
Ferrenberg, Alan M.; Xu, Jiahao; Landau, David P.
2018-04-01
While the three-dimensional Ising model has defied analytic solution, various numerical methods like Monte Carlo, Monte Carlo renormalization group, and series expansion have provided precise information about the phase transition. Using Monte Carlo simulation that employs the Wolff cluster flipping algorithm with both 32-bit and 53-bit random number generators and data analysis with histogram reweighting and quadruple precision arithmetic, we have investigated the critical behavior of the simple cubic Ising Model, with lattice sizes ranging from 163 to 10243. By analyzing data with cross correlations between various thermodynamic quantities obtained from the same data pool, e.g., logarithmic derivatives of magnetization and derivatives of magnetization cumulants, we have obtained the critical inverse temperature Kc=0.221 654 626 (5 ) and the critical exponent of the correlation length ν =0.629 912 (86 ) with precision that exceeds all previous Monte Carlo estimates.
Petroleum migration pathways and charge concentration: A three-dimensional model
Energy Technology Data Exchange (ETDEWEB)
Hindle, A.D. [Anadarko Algeria Corp., Middlesex (United Kingdom)
1997-09-01
Petroleum migration pathways through a basin are determined by the three-dimensional distribution of discontinuous sealing surfaces, which are usually parallel to bedding. The petroleum migrates below the sealing surface, taking the structurally most advantageous route. The three-dimensional distribution of migration pathways within the petroleum system can be modeled on a personal computer using a program based on the parameters discussed in this paper. Application of the model to the Paris and Williston basins demonstrates that a good correlation between predicted pathways and discovered accumulations can be made using simple models. Pathways form a dense network overlying generating areas in the central parts of basins. Toward the basin margins these routes commonly become increasingly focused into discrete pathways by the sealing-surface morphologies. Eventually, these pathways may reach the surface as seepages. It is important to integrate surface outcrops of migration routes (surface seepages) into migration modeling. Deflection of the pathways from the structurally most advantageous route below the sealing surface may be caused by lateral sealing barriers due to faces variation in the carrier rock below the seal, fault juxtaposition, or cross-formational seals such as salt intrusions. Deflection of pathways also occurs where there are hydrodynamic conditions in response to topography-driven groundwater flow. Zones of vertical migration are associated with facies changes along the horizon of the sealing surface into a nonsealing facies, or juxtaposition to nonsealing strata by faults. Vertical migration from either normally or abnormally pressured strata is most likely to occur into normally or lesser pressured strata at intrabasinal highs where hydrocarbons can be stored and transferred at times of temporary seal rupture.
Slab1.0: A three-dimensional model of global subduction zone geometries
Hayes, Gavin P.; Wald, David J.; Johnson, Rebecca L.
2012-01-01
We describe and present a new model of global subduction zone geometries, called Slab1.0. An extension of previous efforts to constrain the two-dimensional non-planar geometry of subduction zones around the focus of large earthquakes, Slab1.0 describes the detailed, non-planar, three-dimensional geometry of approximately 85% of subduction zones worldwide. While the model focuses on the detailed form of each slab from their trenches through the seismogenic zone, where it combines data sets from active source and passive seismology, it also continues to the limits of their seismic extent in the upper-mid mantle, providing a uniform approach to the definition of the entire seismically active slab geometry. Examples are shown for two well-constrained global locations; models for many other regions are available and can be freely downloaded in several formats from our new Slab1.0 website, http://on.doi.gov/d9ARbS. We describe improvements in our two-dimensional geometry constraint inversion, including the use of ‘average’ active source seismic data profiles in the shallow trench regions where data are otherwise lacking, derived from the interpolation between other active source seismic data along-strike in the same subduction zone. We include several analyses of the uncertainty and robustness of our three-dimensional interpolation methods. In addition, we use the filtered, subduction-related earthquake data sets compiled to build Slab1.0 in a reassessment of previous analyses of the deep limit of the thrust interface seismogenic zone for all subduction zones included in our global model thus far, concluding that the width of these seismogenic zones is on average 30% larger than previous studies have suggested.
Bae, Tae Soo; Loan, Peter; Choi, Kuiwon; Hong, Daehie; Mun, Mu Seong
2010-12-01
When car crash experiments are performed using cadavers or dummies, the active muscles' reaction on crash situations cannot be observed. The aim of this study is to estimate muscles' response of the major muscle groups using three-dimensional musculoskeletal model by dynamic simulations of low-speed sled-impact. The three-dimensional musculoskeletal models of eight subjects were developed, including 241 degrees of freedom and 86 muscles. The muscle parameters considering limb lengths and the force-generating properties of the muscles were redefined by optimization to fit for each subject. Kinematic data and external forces measured by motion tracking system and dynamometer were then input as boundary conditions. Through a least-squares optimization algorithm, active muscles' responses were calculated during inverse dynamic analysis tracking the motion of each subject. Electromyography for major muscles at elbow, knee, and ankle joints was measured to validate each model. For low-speed sled-impact crash, experiment and simulation with optimized and unoptimized muscle parameters were performed at 9.4 m/h and 10 m/h and muscle activities were compared among them. The muscle activities with optimized parameters were closer to experimental measurements than the results without optimization. In addition, the extensor muscle activities at knee, ankle, and elbow joint were found considerably at impact time, unlike previous studies using cadaver or dummies. This study demonstrated the need to optimize the muscle parameters to predict impact situation correctly in computational studies using musculoskeletal models. And to improve accuracy of analysis for car crash injury using humanlike dummies, muscle reflex function, major extensor muscles' response at elbow, knee, and ankle joints, should be considered.
Design and Validation of a Three-Dimensional Printed Flexible Canine Otoscopy Teaching Model.
Nibblett, Belle Marie D; Pereira, Mary Mauldin; Sithole, Fortune; Orchard, Paul A D; Bauman, Eric B
2017-04-01
A teaching model was sought to improve canine otoscopy skill and reduce use of teaching dogs. An otoscopy teaching model was printed in a flexible medium on a desktop three-dimensional printer from a magnetic resonance image of a canine external ear canal. The model was mounted in a polyvinyl dog mannequin. Validation of the teaching model was sought from student, faculty, and dog perspective. Student perception of prelaboratory training was assessed using a survey regarding their experience. Otoscopy skill was assessed by faculty grading the ear anatomy visualized as well as the time required to prepare for and perform otoscopy and the time to the dog's first sign of aversion. The time data were used to assess whether there was a reduction in use of teaching dogs. Data from students exposed to the otoscopy model as part of their prelaboratory training (n = 20) were compared with those that were not exposed to the model (n = 19). The students found prelaboratory training with the model significantly more helpful than prelaboratory training without the model in all aspects of otoscopy (P dog use. The students found the model helpful, but the best that can be said is the model did not negatively impact their otoscopy skill acquisition. Although the outcome of the study did not indicate a reduction in teaching dog use, the model has replaced live dog otoscopy in the institute's teaching program for initial canine otoscopy exposure.
Directory of Open Access Journals (Sweden)
Kateryna P. Osadcha
2017-12-01
Full Text Available The article is devoted to some aspects of the formation of future bachelor's graphic competence in computer sciences while teaching the fundamentals for working with three-dimensional modelling means. The analysis, classification and systematization of three-dimensional modelling means are given. The aim of research consists in investigating the set of instruments and classification of three-dimensional modelling means and correlation of skills, which are being formed, concerning inquired ones at the labour market in order to use them further in the process of forming graphic competence during training future bachelors in computer sciences. The peculiarities of the process of forming future bachelor's graphic competence in computer sciences by means of revealing, analyzing and systematizing three-dimensional modelling means and types of three-dimensional graphics at present stage of the development of informational technologies are traced a line round. The result of the research is a soft-ware choice in three-dimensional modelling for the process of training future bachelors in computer sciences.
Directory of Open Access Journals (Sweden)
Kayla F Goliwas
2016-07-01
Full Text Available Breast carcinomas are complex, three-dimensional tissues composed of cancer epithelial cells and stromal components, including fibroblasts and extracellular matrix. In vitro models that more faithfully recapitulate this dimensionality and stromal microenvironment should more accurately elucidate the processes driving carcinogenesis, tumor progression, and therapeutic response. Herein, novel in vitro breast carcinoma surrogates, distinguished by a relevant dimensionality and stromal microenvironment, are described and characterized. A perfusion bioreactor system was used to deliver medium to surrogates containing engineered microchannels and the effects of perfusion, medium composition, and the method of cell incorporation and density of initial cell seeding on the growth and morphology of surrogates were assessed. Perfused surrogates demonstrated significantly greater cell density and proliferation and were more histologically recapitulative of human breast carcinoma than surrogates maintained without perfusion. Although other parameters of the surrogate system, such as medium composition and cell seeding density, affected cell growth, perfusion was the most influential parameter.
Three-dimensional modeling of capsule implosions in OMEGA tetrahedral hohlraums
International Nuclear Information System (INIS)
Schnittman, J. D.; Craxton, R. S.
2000-01-01
Tetrahedral hohlraums have been proposed as a means for achieving the highly uniform implosions needed for ignition with inertial confinement fusion (ICF) [J. D. Schnittman and R. S. Craxton, Phys. Plasmas 3, 3786 (1996)]. Recent experiments on the OMEGA laser system have achieved good drive uniformity consistent with theoretical predictions [J. M. Wallace et al., Phys. Rev. Lett. 82, 3807 (1999)]. To better understand these experiments and future investigations of high-convergence ICF implosions, the three-dimensional (3-D) view-factor code BUTTERCUP has been expanded to model the time-dependent radiation transport in the hohlraum and the hydrodynamic implosion of the capsule. Additionally, a 3-D postprocessor has been written to simulate x-ray images of the imploded core. Despite BUTTERCUP's relative simplicity, its predictions for radiation drive temperatures, fusion yields, and core deformation show close agreement with experiment. (c) 2000 American Institute of Physics
Alberghina, Maria Francesca; Alberghina, Filippo; Allegra, Dario; Di Paola, Francesco; Maniscalco, Laura; Milazzo, Giuseppe; Milotta, Filippo L. M.; Pellegrino, Lorella; Schiavone, Salvatore; Stanco, Filippo
2017-01-01
The Morgantina silver treasure belonging to the Archaeological Museum of Aidone (Sicily) was involved in a three-dimensional (3-D) survey and diagnostics campaign for monitoring the collection over time in anticipation of their temporary transfer to the Metropolitan Museum of Art in New York for a period of 4 years. Using a multidisciplinary approach, a scientific and methodological protocol based on noninvasive techniques to achieve a complete and integrated knowledge of the precious items and their conservation state, as well as to increase their valorization, has been developed. All acquired data, i.e., 3-D models, ultraviolet fluorescence, x-ray images, and chemical information, will be made available, in an integrated way, within a web-oriented platform, which will present an in-progress tool to deepen existing archaeological knowledge and production technologies and to obtain referenced information of the conservation state before and after moving of the collection from its exposure site.
Cell-free DNA in a three-dimensional spheroid cell culture model
DEFF Research Database (Denmark)
Aucamp, Janine; Calitz, Carlemi; Bronkhorst, Abel J.
2017-01-01
state, may be of significant benefit for cfDNA research. Methods CfDNA was isolated from the growth medium of C3A spheroid cultures in rotating bioreactors during both normal growth and treatment with acetaminophen. Spheroid growth was monitored via planimetry, lactate dehydrogenase activity and glucose...... environment. Combining 3D culture and cfDNA research could, therefore, optimize both research fields.......Background Investigating the biological functions of cell-free DNA (cfDNA) is limited by the interference of vast numbers of putative sources and causes of DNA release into circulation. Utilization of three-dimensional (3D) spheroid cell cultures, models with characteristics closer to the in vivo...
El-Shenawee, Magda
2004-01-01
This paper presents an intensive numerical study of the resonance scattering of malignant breast cancer tumors. The three-dimensional electromagnetic model, based on the equivalence theorem, is used to obtain induced electric and magnetic currents on breast and tumor surfaces. The results show that the nonspherical malignant tumor can be characterized, based on its spectra, regardless of orientation, incident polarization, or incident or scattered directions. The spectra of the tumor depend solely upon its physical characteristics (i.e., shape and electrical properties); however, their locations are not functions of the depth of the tumor beneath the breast surface. This paper can be a guide in the selection of the frequency range at which the tumor resonates to produce the maximum signature at the receiver.
Segmentation of Three Dimensional Cell Culture Models from aSingle Focal Plane
Energy Technology Data Exchange (ETDEWEB)
Chang, Hang; Parvin, Bahram
2006-11-01
Three dimensional cell culture models offer new opportunities for development of computational techniques for segmentation and localization. These assays have a unique signature of a clump of cells that correspond to a functioning colony. Often the nuclear compartment is labeled and then imaged with fluorescent microscopy to provide context for protein localization. These colonies are first delineated from background using the level set method. Within each colony, nuclear regions are then bounded by their center of mass through radial voting, and a local neighborhood for each nucleus is established through Voronoi tessellation. Finally, the level set method is applied again within each Voronoi region to delineate the nuclear compartment. The paper concludes with the application of the proposed method to a dataset of experimental data demonstrating a stable solution when iterative radial voting and level set methods are used synergistically.
Gao, Yuan; Haapasalo, Markus; Shen, Ya; Wu, Hongkun; Li, Bingdong; Ruse, N Dorin; Zhou, Xuedong
2009-09-01
Root canal irrigation plays an important role in the debridement and disinfection of the root canal system and is an integral part of root canal preparation procedures. The aim was to construct a three-dimensional computational fluid dynamics (CFD) model of root canal irrigation, with a suitable turbulence model, and validate it to provide a novel method for studying the root canal irrigation. A camcorder was used to record the effect of irrigation in the in vitro model. An exact replica of the geometry and the physical parameters of the in vitro irrigation model were used in CFD analysis, considering four turbulent models. The in vitro irrigation model was used as the reference for the evaluation of the CFD models. The result showed that CFD analysis based on a shear stress transport (SST) k-omega turbulence model was in close agreement with the in vitro irrigation model. The in vitro and CFD analyses showed that the irrigant in the curved canal flushes only up to a limited distance beyond the tip of the needle. The results of the CFD analysis also showed that laminar flow exists in the needle lumen and transit the transitional and turbulent flow around the side-vent outlet of the needle and needle tip. The results suggested that CFD based on a SST k-omega turbulence model has the potential to serve as a platform for the study of root canal irrigation.
Three-Dimensional Modeling of Fluid and Heat Transport in an Accretionary Complex
Paula, C. A.; Ge, S.; Screaton, E. J.
2001-12-01
As sediments are scraped off of the subducting oceanic crust and accreted to the overriding plate, the rapid loading causes pore pressures in the underthrust sediments to increase. The change in pore pressure drives fluid flow and heat transport within the accretionary complex. Fluid is channeled along higher permeability faults and fractures and expelled at the seafloor. In this investigation, we examined the effects of sediment loading on fluid flow and thermal transport in the decollement at the Barbados Ridge subduction zone. Both the width and thickness of the Barbados Ridge accretionary complex increase from north to south. The presence of mud diapers south of the Tiburon Rise and an observed southward decrease in heat flow measurements indicate that the increased thickness of the southern Barbados accretionary prism affects the transport of chemicals and heat by fluids. The three-dimensional geometry and physical properties of the accretionary complex were utilized to construct a three-dimensional fluid flow/heat transport model. We calculated the pore pressure change due to a period of sediment loading and added this to steady-state pressure conditions to generate initial conditions for transient simulations. We then examined the diffusion of pore pressure and possible perturbation of the thermal regime over time due to loading of the underthrust sediments. The model results show that the sediment-loading event was sufficient to create small temperature fluctuations in the decollement zone. The magnitude of temperature fluctuation in the decollement was greatest at the deformation front but did not vary significantly from north to south of the Tiburon Rise.
Gerhardt, L. A.
1985-09-01
The sensing of three dimensional information is addressed, the display/representation of three dimensional information is considered. With respect to the sensing of three dimensional information, a variety of approaches are discussed including the use of structured light, the use of displaced sensors to develop stereo pairs, and coherence processing and time of flight measurement. Other techniques described are interpretation of object motion as a measurement of depth perception, and general methods for utilizing depth of field. The advantages and disadvantages of each are discussed and comparisons made. Three dimensional display techniques is also discussed. The appraoches covered include graphics, stereo pairs, holograms, vibrating mirrors, and other optical systems. Applications are reviewed with examples of results such as the use of vibrating mirror technology for the three dimensional display of compterized tomography. Solid modelling as an approach to the display and representation of three dimensional information is reviewed. Following a definition of solid modelling, the advantages of this generic approach are reviewed and analyzed. The relationship of solid modelling to robotics and artificial intelligence is made, and trends cited with respect to hardware costs, portability of software, computational efficiency, display resolution, and neutral data bases. The paper concludes by giving examples of some of the key applications of solid modelling in the automative industry, aircraft industry and CAM, among others.
Gastelum, Alfonso; Mata, Lucely; Brito-de-la-Fuente, Edmundo; Delmas, Patrice; Vicente, William; Salinas-Vázquez, Martín; Ascanio, Gabriel; Marquez, Jorge
2016-03-01
We aimed to provide realistic three-dimensional (3D) models to be used in numerical simulations of peristaltic flow in patients exhibiting difficulty in swallowing, also known as dysphagia. To this end, a 3D model of the upper gastrointestinal tract was built from the color cryosection images of the Visible Human Project dataset. Regional color heterogeneities were corrected by centering local histograms of the image difference between slices. A voxel-based model was generated by stacking contours from the color images. A triangle mesh was built, smoothed and simplified. Visualization tools were developed for browsing the model at different stages and for virtual endoscopy navigation. As result, a computer model of the esophagus and the stomach was obtained, mainly for modeling swallowing disorders. A central-axis curve was also obtained for virtual navigation and to replicate conditions relevant to swallowing disorders modeling. We show renderings of the model and discuss its use for simulating swallowing as a function of bolus rheological properties. The information obtained from simulation studies with our model could be useful for physicians in selecting the correct nutritional emulsions for patients with dysphagia.
Modeling extreme (Carrington-type) space weather events using three-dimensional MHD code simulations
Ngwira, C. M.; Pulkkinen, A. A.; Kuznetsova, M. M.; Glocer, A.
2013-12-01
There is growing concern over possible severe societal consequences related to adverse space weather impacts on man-made technological infrastructure and systems. In the last two decades, significant progress has been made towards the modeling of space weather events. Three-dimensional (3-D) global magnetohydrodynamics (MHD) models have been at the forefront of this transition, and have played a critical role in advancing our understanding of space weather. However, the modeling of extreme space weather events is still a major challenge even for existing global MHD models. In this study, we introduce a specially adapted University of Michigan 3-D global MHD model for simulating extreme space weather events that have a ground footprint comparable (or larger) to the Carrington superstorm. Results are presented for an initial simulation run with ``very extreme'' constructed/idealized solar wind boundary conditions driving the magnetosphere. In particular, we describe the reaction of the magnetosphere-ionosphere system and the associated ground induced geoelectric field to such extreme driving conditions. We also discuss the results and what they might mean for the accuracy of the simulations. The model is further tested using input data for an observed space weather event to verify the MHD model consistence and to draw guidance for future work. This extreme space weather MHD model is designed specifically for practical application to the modeling of extreme geomagnetically induced electric fields, which can drive large currents in earth conductors such as power transmission grids.
A method for automatic feature points extraction of human vertebrae three-dimensional model
Wu, Zhen; Wu, Junsheng
2017-05-01
A method for automatic extraction of the feature points of the human vertebrae three-dimensional model is presented. Firstly, the statistical model of vertebrae feature points is established based on the results of manual vertebrae feature points extraction. Then anatomical axial analysis of the vertebrae model is performed according to the physiological and morphological characteristics of the vertebrae. Using the axial information obtained from the analysis, a projection relationship between the statistical model and the vertebrae model to be extracted is established. According to the projection relationship, the statistical model is matched with the vertebrae model to get the estimated position of the feature point. Finally, by analyzing the curvature in the spherical neighborhood with the estimated position of feature points, the final position of the feature points is obtained. According to the benchmark result on multiple test models, the mean relative errors of feature point positions are less than 5.98%. At more than half of the positions, the error rate is less than 3% and the minimum mean relative error is 0.19%, which verifies the effectiveness of the method.
A three-dimensional finite element model for biomechanical analysis of the hip.
Chen, Guang-Xing; Yang, Liu; Li, Kai; He, Rui; Yang, Bin; Zhan, Yan; Wang, Zhi-Jun; Yu, Bing-Nin; Jian, Zhe
2013-11-01
The objective of this study was to construct a three-dimensional (3D) finite element model of the hip. The images of the hip were obtained from Chinese visible human dataset. The hip model includes acetabular bone, cartilage, labrum, and bone. The cartilage of femoral head was constructed using the AutoCAD and Solidworks software. The hip model was imported into ABAQUS analysis system. The contact surface of the hip joint was meshed. To verify the model, the single leg peak force was loaded, and contact area of the cartilage and labrum of the hip and pressure distribution in these structures were observed. The constructed 3D hip model reflected the real hip anatomy. Further, this model reflected biomechanical behavior similar to previous studies. In conclusion, this 3D finite element hip model avoids the disadvantages of other construction methods, such as imprecision of cartilage construction and the absence of labrum. Further, it provides basic data critical for accurately modeling normal and abnormal loads, and the effects of abnormal loads on the hip.
Directory of Open Access Journals (Sweden)
Tarig Magdeldin
2014-07-01
Full Text Available The preclinical development process of chemotherapeutic drugs is often carried out in two-dimensional monolayer cultures. However, a considerable amount of evidence demonstrates that two-dimensional cell culture does not accurately reflect the three-dimensional in vivo tumour microenvironment, specifically with regard to gene expression profiles, oxygen and nutrient gradients and pharmacokinetics. With this objective in mind, we have developed and established a physiologically relevant three-dimensional in vitro model of colorectal cancer based on the removal of interstitial fluid from collagen type I hydrogels. We employed the RAFT™ (Real Architecture For 3D Tissue system for producing three-dimensional cultures to create a controlled reproducible, multiwell testing platform. Using the HT29 and HCT116 cell lines to model epidermal growth factor receptor expressing colorectal cancers, we characterized three-dimensional cell growth and morphology in addition to the anti-proliferative effects of the anti–epidermal growth factor receptor chemotherapeutic agent cetuximab in comparison to two-dimensional monolayer cultures. Cells proliferated well for 14 days in three-dimensional culture and formed well-defined cellular aggregates within the concentrated collagen matrix. Epidermal growth factor receptor expression levels revealed a twofold and threefold increase in three-dimensional cultures for both HT29 and HCT116 cells in comparison to two-dimensional monolayers, respectively (p < 0.05; p < 0.01. Cetuximab efficacy was significantly lower in HT29 three-dimensional cultures in comparison to two-dimensional monolayers, whereas HCT116 cells in both two-dimension and three-dimension were non-responsive to treatment in agreement with their KRAS mutant status. In summary, these results confirm the use of a three-dimensional in vitro cancer model as a suitable drug-screening platform for in vitro pharmacological testing.
Xiao, Tiaojie; Liu, Yun; Wang, Yun; Fu, Li-Yun
2018-02-01
It is important to understand how magnetotelluric (MT) modeling can most effectively be performed in general anisotropic media. However, previous studies in this area have mainly focused on the use of one-dimensional (1D) and two-dimensional (2D) algorithms. Thus, building on earlier work, it is important to study the performance of three-dimensional (3D) modeling in arbitrary conductivity media; therefore, an edge-based finite element (FE) method has been developed for 3D MT modeling in arbitrary conductivity media. This approach is based on the initial derivation of a series of equivalent variational equations that are based on Maxwell equations, generated using the weighted residual method. Specific values were then obtained for coefficient matrixes of this edge-based FE method using hexahedral meshes, and the algorithm was verified by comparing its results with finite difference (FD) solutions generated using a 2D anisotropic model. Finally, the results of a 3D anisotropic model were analyzed detailed for three conditions; another 3D anisotropic model was designed and its results were compared with two isotropic models'.
International Nuclear Information System (INIS)
Liang, Zhong Wei; Wang, Yi Jun; Ye, Bang Yan; Brauwer, Richard Kars
2012-01-01
In inspecting the detailed performance results of surface precision modeling in different external parameter conditions, the integrated chip surfaces should be evaluated and assessed during topographic spatial modeling processes. The application of surface fitting algorithms exerts a considerable influence on topographic mathematical features. The influence mechanisms caused by different surface fitting algorithms on the integrated chip surface facilitate the quantitative analysis of different external parameter conditions. By extracting the coordinate information from the selected physical control points and using a set of precise spatial coordinate measuring apparatus, several typical surface fitting algorithms are used for constructing micro topographic models with the obtained point cloud. In computing for the newly proposed mathematical features on surface models, we construct the fuzzy evaluating data sequence and present a new three dimensional fuzzy quantitative evaluating method. Through this method, the value variation tendencies of topographic features can be clearly quantified. The fuzzy influence discipline among different surface fitting algorithms, topography spatial features, and the external science parameter conditions can be analyzed quantitatively and in detail. In addition, quantitative analysis can provide final conclusions on the inherent influence mechanism and internal mathematical relation in the performance results of different surface fitting algorithms, topographic spatial features, and their scientific parameter conditions in the case of surface micro modeling. The performance inspection of surface precision modeling will be facilitated and optimized as a new research idea for micro-surface reconstruction that will be monitored in a modeling process
Verifying three-dimensional skull model reconstruction using cranial index of symmetry.
Kung, Woon-Man; Chen, Shuo-Tsung; Lin, Chung-Hsiang; Lu, Yu-Mei; Chen, Tzu-Hsuan; Lin, Muh-Shi
2013-01-01
Difficulty exists in scalp adaptation for cranioplasty with customized computer-assisted design/manufacturing (CAD/CAM) implant in situations of excessive wound tension and sub-cranioplasty dead space. To solve this clinical problem, the CAD/CAM technique should include algorithms to reconstruct a depressed contour to cover the skull defect. Satisfactory CAM-derived alloplastic implants are based on highly accurate three-dimensional (3-D) CAD modeling. Thus, it is quite important to establish a symmetrically regular CAD/CAM reconstruction prior to depressing the contour. The purpose of this study is to verify the aesthetic outcomes of CAD models with regular contours using cranial index of symmetry (CIS). From January 2011 to June 2012, decompressive craniectomy (DC) was performed for 15 consecutive patients in our institute. 3-D CAD models of skull defects were reconstructed using commercial software. These models were checked in terms of symmetry by CIS scores. CIS scores of CAD reconstructions were 99.24±0.004% (range 98.47-99.84). CIS scores of these CAD models were statistically significantly greater than 95%, identical to 99.5%, but lower than 99.6% (ppairs signed rank test). These data evidenced the highly accurate symmetry of these CAD models with regular contours. CIS calculation is beneficial to assess aesthetic outcomes of CAD-reconstructed skulls in terms of cranial symmetry. This enables further accurate CAD models and CAM cranial implants with depressed contours, which are essential in patients with difficult scalp adaptation.
Three-dimensional Modeling of Tidal Hydrodynamics in the San Francisco Estuary
Directory of Open Access Journals (Sweden)
Edward S. Gross
2010-01-01
Full Text Available Simulations of circulation in the San Francisco Estuary were performed with the three-dimensional TRIM3D hydrodynamic model using a generic length scale turbulence closure. The model was calibrated to reproduce observed tidal elevations, tidal currents, and salinity observations in the San Francisco Estuary using data collected during 1996-1998, a period of high and variable freshwater flow. It was then validated for 1994-1995, with emphasis on spring of 1994, a period of intensive data collection in the northern estuary. The model predicts tidal elevations and tidal currents accurately, and realistically predicts salinity at both the seasonal and tidal time scales. The model represents salt intrusion into the estuary accurately, and therefore accurately represents the salt balance. The model’s accuracy is adequate for its intended purposes of predicting salinity, analyzing gravitational circulation, and driving a particle-tracking model. Two applications were used to demonstrate the utility of the model. We estimated the components of the longitudinal salt flux and examined their dependence on flow conditions, and compared predicted salt intrusion with estimates from two empirical models.
Three-dimensional electromagnetic model of the pulsed-power Z-pinch accelerator
Directory of Open Access Journals (Sweden)
D. V. Rose
2010-01-01
Full Text Available A three-dimensional, fully electromagnetic model of the principal pulsed-power components of the 26-MA ZR accelerator [D. H. McDaniel et al., in Proceedings of the 5th International Conference on Dense Z-Pinches (AIP, New York, 2002, p. 23] has been developed. This large-scale simulation model tracks the evolution of electromagnetic waves through the accelerator’s intermediate-storage capacitors, laser-triggered gas switches, pulse-forming lines, water switches, triplate transmission lines, and water convolute to the vacuum insulator stack. The insulator-stack electrodes are coupled to a transmission-line circuit model of the four-level magnetically insulated vacuum-transmission-line section and double-post-hole convolute. The vacuum-section circuit model is terminated by a one-dimensional self-consistent dynamic model of an imploding z-pinch load. The simulation results are compared with electrical measurements made throughout the ZR accelerator, and are in good agreement with the data, especially for times until peak load power. This modeling effort demonstrates that 3D electromagnetic models of large-scale, multiple-module, pulsed-power accelerators are now computationally tractable. This, in turn, presents new opportunities for simulating the operation of existing pulsed-power systems used in a variety of high-energy-density-physics and radiographic applications, as well as even higher-power next-generation accelerators before they are constructed.
A three-dimensional model for thermal analysis in a vanadium flow battery
International Nuclear Information System (INIS)
Zheng, Qiong; Zhang, Huamin; Xing, Feng; Ma, Xiangkun; Li, Xianfeng; Ning, Guiling
2014-01-01
Highlights: • A three-dimensional model for thermal analysis in a VFB has been developed. • A quasi-static thermal behavior and temperature spatial distribution were showed. • Ohmic heat gets vital in heat generation if applied current density is large enough. • A lower porosity or a faster flow shows a more uniform temperature distribution. • The model shows good prospect in heat and temperature management for a VFB. - Abstract: A three-dimensional model for thermal analysis has been developed to gain a better understanding of thermal behavior in a vanadium flow battery (VFB). The model is based on a comprehensive description of mass, momentum, charge and energy transport and conservation, combining with a global kinetic model for reactions involving all vanadium species. The emphasis in this paper is placed on the heat losses inside a cell. A quasi-static behavior of temperature and the temperature spatial distribution were characterized via the thermal model. The simulations also indicate that the heat generation exhibits a strong dependence on the applied current density. The reaction rate and the over potential rise with an increased applied current density, resulting in the electrochemical reaction heat rises proportionally and the activation heat rises at a parabolic rate. Based on the Ohm’s law, the ohmic heat rises at a parabolic rate when the applied current density increases. As a result, the determining heat source varies when the applied current density changes. While the relative contribution of the three types of heat is dependent on the cell materials and cell geometry, the regularities of heat losses can also be attained via the model. In addition, the electrochemical reaction heat and activation heat have a lack of sensitivity to the porosity and flow rate, whereas an obvious increase of ohmic heat has been observed with the rise of the porosity. A lower porosity or a faster flow shows a better uniformity of temperature distribution in
Three-dimensional modeling of radiative and convective exchanges in the urban atmosphere
International Nuclear Information System (INIS)
Qu, Yongfeng
2011-01-01
In many micro-meteorological studies, building resolving models usually assume a neutral atmosphere. Nevertheless, urban radiative transfers play an important role because of their influence on the energy budget. In order to take into account atmospheric radiation and the thermal effects of the buildings in simulations of atmospheric flow and pollutant dispersion in urban areas, we have developed a three-dimensional (3D) atmospheric radiative scheme, in the atmospheric module of the Computational Fluid Dynamics model Code-Saturne. The radiative scheme was previously validated with idealized cases, using as a first step, a constant 3D wind field. In this work, the full coupling of the radiative and thermal schemes with the dynamical model is evaluated. The aim of the first part is to validate the full coupling with the measurements of the simple geometry from the 'Mock Urban Setting Test' (MUST) experiment. The second part discusses two different approaches to model the radiative exchanges in urban area with a comparison between Code-Saturne and SOLENE. The third part applies the full coupling scheme to show the contribution of the radiative transfer model on the airflow pattern in low wind speed conditions in a 3D urban canopy. In the last part we use the radiative-dynamics coupling to simulate a real urban environment and validate the modeling approach with field measurements from the 'Canopy and Aerosol Particles Interactions in Toulouse Urban Layer' (CAPITOUL). (author) [fr
Three-dimensional numerical modelling of a magnetically deflected dc transferred arc in argon
Blais, A; Boulos, M I
2003-01-01
The aim of this work is to develop a numerical model for the deflection of dc transferred arcs using an external magnetic field as a first step into the modelling of industrial arc furnaces. The arc is deflected by the use of a conductor aligned parallel to the arc axis through which flows an electric current. The model is validated by comparing the results of axisymmetric calculations to modelling results from the scientific literature. The present model is found to be a good representation of the electric dc arc as differences with the literature are easily explained by model parameters such as the critical boundary conditions at the electrodes. Transferred arc cases exhibit the expected behaviour as the temperature T, the velocity v-vector and the electrical potential drop DELTA phi all increase with the arc current I and the argon flow rate Q. Three-dimensional geometry is implemented, enabling one to numerically deflect the arc. For the deflected arc cases, the deflection increases with the arc current I...
Characterization and three-dimensional reconstruction of synthetic bone model foams
Energy Technology Data Exchange (ETDEWEB)
Gómez, S. [Interdepartment Research Group for the Applied Scientific Collaboration (IRGASC), Division of Biomaterials and Bioengineering, Technical University of Catalonia (UPC), Avda. Diagonal 647, E-08028 Barcelona (Spain); Vlad, M.D. [Interdepartment Research Group for the Applied Scientific Collaboration (IRGASC), Division of Biomaterials and Bioengineering, Technical University of Catalonia (UPC), Avda. Diagonal 647, E-08028 Barcelona (Spain); Faculty of Medical Bioengineering, “Gr. T. Popa” University of Medicine and Pharmacy, Str. Kogalniceanu 9-13, 700454 Iasi (Romania); López, J. [Interdepartment Research Group for the Applied Scientific Collaboration (IRGASC), Division of Biomaterials and Bioengineering, Technical University of Catalonia (UPC), Avda. Diagonal 647, E-08028 Barcelona (Spain); Navarro, M. [Centre de Biotecnologia Animal i de Teràpia Gènica (CBATEG), Departament de Sanitat i d' Anatomia Animals, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Cerdanyola del Vallès (Spain); Fernández, E., E-mail: enrique.fernandez@upc.edu [Interdepartment Research Group for the Applied Scientific Collaboration (IRGASC), Division of Biomaterials and Bioengineering, Technical University of Catalonia (UPC), Avda. Diagonal 647, E-08028 Barcelona (Spain)
2013-08-01
Sawbones© open-cell foams with different porosity grades are being used as synthetic bone-like models for in vitro mechanical and infiltration experiments. However, a comprehensive characterization of these foams is not available and there is a lack of reliable information about them. For this reason two of these foams (Refs. 1522-505 and -507) have been characterized at the micro architectural level by scanning electron microscopy, computed tomography and image data analysis. BoneJ open software and ImageJ open software were used to obtain the characteristic histomorphometric parameters and the three dimensional virtual models of the foams. The results showed that both foams, while having different macro porosities, appeared undistinguishable at the micro scale. Moreover, the micro structural features resembled those of osteoporotic rather than healthy trabecular bone. It is concluded that Sawbones© foams behave reasonably as synthetic bone-like models. Consequently, their use is recommended for in vitro comparison purposes of both mechanical and infiltration testing performed in real vertebra. Finally, the virtual models obtained, which are available under request, can favour comparisons between future self-similar in vitro experiments and computer simulations. - Highlights: • Sawbones© model foams have been scanned by μ-CT. • Histomorphometric indices and 3D virtual models have been obtained. • The results will be of use to understand biocement vertebra infiltration studies.
Protopappas, Vasilios C; Kourtis, Iraklis C; Kourtis, Lampros C; Malizos, Konstantinos N; Massalas, Christos V; Fotiadis, Dimitrios I
2007-06-01
The use of guided waves has recently drawn significant interest in the ultrasonic characterization of bone aiming at supplementing the information provided by traditional velocity measurements. This work presents a three-dimensional finite element study of guided wave propagation in intact and healing bones. A model of the fracture callus was constructed and the healing course was simulated as a three-stage process. The dispersion of guided modes generated by a broadband 1-MHz excitation was represented in the time-frequency domain. Wave propagation in the intact bone model was first investigated and comparisons were then made with a simplified geometry using analytical dispersion curves of the tube modes. Then, the effect of callus consolidation on the propagation characteristics was examined. It was shown that the dispersion of guided waves was significantly influenced by the irregularity and anisotropy of the bone. Also, guided waves were sensitive to material and geometrical changes that take place during healing. Conversely, when the first-arriving signal at the receiver corresponded to a nondispersive lateral wave, its propagation velocity was almost unaffected by the elastic symmetry and geometry of the bone and also could not characterize the callus tissue throughout its thickness. In conclusion, guided waves can enhance the capabilities of ultrasonic evaluation.
Mamou, Jonathan M.
This dissertation investigated how three-dimensional (3D) tissue models can be used to improve ultrasonic tissue characterization (UTC) techniques. Anatomic sites in tissue responsible for ultrasonic scattering are unknown, which limits the potential applications of ultrasound for tumor diagnosis. Accurate 3D models of tumor tissues may help identify the scattering sites. Three mammary tumors were investigated: a rat fibroadenoma, a mouse carcinoma, and a mouse sarcoma. A 3D acoustic tissue model, termed 3D impedance map (3DZM), was carefully constructed from consecutive histologic sections for each tumor. Spectral estimates (scatterer size and acoustic concentration) were obtained from the 3DZMs and compared to the same estimates obtained with ultrasound. Scatterer size estimates for three tumors were found to be similar (within 10%). The 3DZMs were also used to extract tissue-specific scattering models. The scattering models were found to allow clear distinction between the three tumors. This distinction demonstrated that UTC techniques may be helpful for noninvasive clinical tumor diagnosis.
A three-dimensional finite element model for the mechanics of cell-cell interactions.
Viens, Denis; Brodland, G Wayne
2007-10-01
Technical challenges, including significant ones associated with cell rearrangement, have hampered the development of three-dimensional finite element models for the mechanics of embryonic cells. These challenges have been overcome by a new formulation in which the contents of each cell, assumed to have a viscosity mu, are modeled using a system of orthogonal dashpots. This approach overcomes a stiffening artifact that affects more traditional models, in which space-filling viscous elements are used to model the cytoplasm. Cells are assumed to be polyhedral in geometry, and each n-sided polygonal face is subdivided into n triangles with a common node at the face center so that it needs not remain flat. A constant tension gamma is assumed to act along each cell-cell interface, and cell rearrangements occur through one of two complementary topological transformations. The formulation predicts mechanical interactions between pairs of similar or dissimilar cells that are consistent with experiments, two-dimensional simulations, contact angle theory, and intracellular pressure calculations. Simulations of the partial engulfment of one tissue type by another show that the formulation is able to model aggregates of several hundred cells without difficulty. Simulations carried out using this formulation suggest new experimental approaches for measuring cell surface tensions and interfacial tensions. The formulation holds promise as a tool for gaining insight into the mechanics of isolated or aggregated embryonic cells and for the design and interpretation of experiments that involve them.
Three-Dimensional Modeling of a Robotic Fish Based on Real Carp Locomotion
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Gonca Ozmen Koca
2018-01-01
Full Text Available This work focuses on developing a complete non-linear dynamic model comprising entirely kinematic and hydrodynamic effects of Carangiform locomotion based on the Lagrange approach by adapting the parameters and behaviors of a real carp. In order to imitate biological features, swimming patterns of a real carp for forward, turning and up-down motions are analyzed by using the Kineova 8.20 software. The proportional optimum link lengths according to actual size, swimming speed, flapping frequency, proportional physical parameters and different swimming motions of the real carp are investigated with the designed robotic fish model. Three-dimensional (3D locomotion is evaluated by tracking two trajectories in a MATLAB environment. A Reaching Law Control (RLC approach for inner loop (Euler angles-speed control and a guidance system for the outer loop (orientation control are proposed to provide an effective closed-loop control performance. In order to illustrate the 3D performance of the proposed closed loop control system in a virtual reality platform, the designed robotic fish model is also implemented using the Virtual Reality Modeling Language (VRML. Simulation and experimental analysis show that the proposed model gives us significant key solutions to design a fish-like robotic prototype.
McBride, D.; Cross, M.; Croft, N.; Bennett, C.; Gebhardt, J.
2006-03-01
A computational procedure is presented for solving complex variably saturated flows in porous media, that may easily be implemented into existing conventional finite-volume-based computational fluid dynamics codes, so that their functionality might be geared upon to readily enable the modelling of a complex suite of interacting fluid, thermal and chemical reaction process physics. This procedure has been integrated within a multi-physics finite volume unstructured mesh framework, allowing arbitrarily complex three-dimensional geometries to be modelled. The model is particularly targeted at ore heap-leaching processes, which encounter complex flow problems, such as infiltration into dry soil, drainage, perched water tables and flow through heterogeneous materials, but is equally applicable to any process involving flow through porous media, such as in environmental recovery processes. The computational procedure is based on the mixed form of the classical Richards equation, employing an adaptive transformed mixed algorithm that is numerically robust and significantly reduces compute (or CPU) time. The computational procedure is accurate (compares well with other methods and analytical data), comprehensive (representing any kind of porous flow model), and is computationally efficient. As such, this procedure provides a suitable basis for the implementation of large-scale industrial heap-leach models.
Upasani, Vidyadhar V; Jeffords, Megan E; Farnsworth, Christine L; Padilla, David; Lopreiato, Nick; Aruwajoye, Olumide O; Kim, Harry K W
2017-09-15
Legg-Calve-Perthes disease (LCPD) is a childhood form of ischemic osteonecrosis marked by development of severe femoral head deformity and premature osteoarthritis. The pathogenesis of femoral head deformity has been studied extensively using a piglet model of ischemic osteonecrosis, however, accompanying acetabular changes have not been investigated. The purpose of this study was to determine if acetabular changes accompany femoral head deformity in a well-established piglet model of LCPD and to define the acetabular changes using three dimensional computed tomography (3-D CT) and modeling. Twenty-four piglets were surgically induced with ischemic osteonecrosis on the right side. The contralateral hip was used as control. At 8 weeks postoperative, pelvi were retrieved and imaged with CT. Custom software was used to measure acetabular morphologic parameters on 3-D CT images. Moderate to severe femoral head deformities were present in all animals. Acetabula with accompanying femoral head deformity had a significant decrease in acetabular version and tilt (p femoral head deformity following ischemic osteonecrosis produces specific and predictable changes to the shape of the acetabulum. Acetabular changes described in patients with LCPD were observed in the piglet model. This model may serve as a valuable tool to elucidate the relationship between femoral head and acetabular deformities. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.
2006-06-01
The New Hampshire Department of Transportation initiated this research to develop a geographical information system (GIS) that : visualizes subsurface conditions three dimensionally by pulling together geotechnical data containing spatial references....
Biomechanical model of the thorax under blast loading: a three dimensional numerical study.
Goumtcha, Aristide Awoukeng; Thoral-Pierre, Karine; Roth, Sébastien
2014-12-01
Injury mechanisms due to high speed dynamic loads, such as blasts, are not well understood. These research fields are widely investigated in the literature, both at the experimental and numerical levels, and try to answer questions about the safety and efficiency of protection devices or biomechanical traumas. At a numerical level, the development of powerful mathematical models tends to study tolerance limits and injury mechanisms in order to avoid experimental tests which cannot be easily conducted. In a military framework, developing a fighter/soldier numerical model can help to the understanding of many traumas which are specific to soldier injuries, like mines, ballistic impacts or blast traumas. The aim of this study is to investigate the consequences of violent loads in terms of human body response, submitting a developed and validated three-dimensional thorax finite element (FE) model to blast loadings. Specific formulations of FE methods are used to simulate this loading, and its consequence on the biomechanical model. Mechanical parameters such as pressure in the air field and also in internal organs are observed, and these values are compared to the experimental data in the literature. This study gives encouraging results and allows going further in soldier trauma investigations. Copyright © 2014 John Wiley & Sons, Ltd.
A three-dimensional mathematical model for liquid-fed direct methanol fuel cells
Ge, Jiabin; Liu, Hongtan
A three-dimensional, single-phase, multi-component mathematical model has been developed for a liquid-fed direct methanol fuel cell (DMFC). The traditional continuity, momentum, and species conservation equations are coupled with electrochemical kinetics in both the anode and cathode catalyst layer. At the anode side, the liquid phase is considered, and at the cathode side only the gas phase is considered. Methanol crossover due to both diffusion and electro-osmotic drag from the anode to the cathode is taken into consideration and the effect is incorporated into the model using a mixed-potential at the cathode. A finite-volume-based CFD technique is used to develop the in-house numerical code and the code is successfully used to simulate the fuel cell performance as well as the multi-component behavior in a DMFC. The modeling results of polarization curves compare well with our experimental data. Subsequently, the model is used to study the effects of methanol crossover, the effects of porosities of the diffusion layer and the catalyst layer, the effects of methanol flow rates, and the effects of the channel shoulder widths.
A three-dimensional model of solar radiation transfer in a non-uniform plant canopy
Levashova, N. T.; Mukhartova, Yu V.
2018-01-01
A three-dimensional (3D) model of solar radiation transfer in a non-uniform plant canopy was developed. It is based on radiative transfer equations and a so-called turbid medium assumption. The model takes into account the multiple scattering contributions of plant elements in radiation fluxes. These enable more accurate descriptions of plant canopy reflectance and transmission in different spectral bands. The model was applied to assess the effects of plant canopy heterogeneity on solar radiation transmission and to quantify the difference in a radiation transfer between photosynthetically active radiation PAR (=0.39-0.72 μm) and near infrared solar radiation NIR (Δλ = 0.72-3.00 μm). Comparisons of the radiative transfer fluxes simulated by the 3D model within a plant canopy consisted of sparsely planted fruit trees (plant area index, PAI - 0.96 m2 m-2) with radiation fluxes simulated by a one-dimensional (1D) approach, assumed horizontal homogeneity of plant and leaf area distributions, showed that, for sunny weather conditions with a high solar elevation angle, an application of a simplified 1D approach can result in an underestimation of transmitted solar radiation by about 22% for PAR, and by about 26% for NIR.
Directory of Open Access Journals (Sweden)
Woo Chul Jeong
2015-08-01
Full Text Available Electromagnetic fields provide fundamental data for the imaging of electrical tissue properties, such as conductivity and permittivity, in recent magnetic resonance (MR-based tissue property mapping. The induced voltage, current density, and magnetic flux density caused by externally injected current are critical factors for determining the image quality of electrical tissue conductivity. As a useful tool to identify bio-electromagnetic phenomena, precise approaches are required to understand the exact responses inside the human body subject to an injected currents. In this study, we provide the numerical simulation results of electromagnetic field mapping of brain tissues using a MR-based conductivity imaging method. First, we implemented a realistic three-dimensional human anisotropic head model using high-resolution anatomical and diffusion tensor MR images. The voltage, current density, and magnetic flux density of brain tissues were imaged by injecting 1 mA of current through pairs of electrodes on the surface of our head model. The current density map of anisotropic brain tissues was calculated from the measured magnetic flux density based on the linear relationship between the water diffusion tensor and the electrical conductivity tensor. Comparing the current density to the previous isotropic model, the anisotropic model clearly showed the differences between the brain tissues. This originates from the enhanced signals by the inherent conductivity contrast as well as the actual tissue condition resulting from the injected currents.
Three-dimensional cell culture model utilization in cancer stem cell research.
Bielecka, Zofia F; Maliszewska-Olejniczak, Kamila; Safir, Ilan J; Szczylik, Cezary; Czarnecka, Anna M
2017-08-01
Three-dimensional (3D) cell culture models are becoming increasingly popular in contemporary cancer research and drug resistance studies. Recently, scientists have begun incorporating cancer stem cells (CSCs) into 3D models and modifying culture components in order to mimic in vivo conditions better. Currently, the global cell culture market is primarily focused on either 3D cancer cell cultures or stem cell cultures, with less focus on CSCs. This is evident in the low product availability officially indicated for 3D CSC model research. This review discusses the currently available commercial products for CSC 3D culture model research. Additionally, we discuss different culture media and components that result in higher levels of stem cell subpopulations while better recreating the tumor microenvironment. In summary, although progress has been made applying 3D technology to CSC research, this technology could be further utilized and a greater number of 3D kits dedicated specifically to CSCs should be implemented. © 2016 The Authors. Biological Reviews published by John Wiley & Sons Ltd on behalf of Cambridge Philosophical Society.
Three-dimensional model of a selective theophylline-binding RNA molecule
Energy Technology Data Exchange (ETDEWEB)
Tung, Chang-Shung; Oprea, T.I.; Hummer, G.; Garcia, A.E.
1995-07-01
We propose a three-dimensional (3D) model for an RNA molecule that selectively binds theophylline but not caffeine. This RNA, which was found using SELEX [Jenison, R.D., et al., Science (1994) 263:1425] is 10,000 times more specific for theophylline (Kd=320 nM) than for caffeine (Kd=3.5 mM), although the two ligands are identical except for a methyl group substituted at N7 (present only in caffeine). The binding affinity for ten xanthine-based ligands was used to derive a Comparative Molecular Field Analysis (CoMFA) model (R{sup 2} = 0.93 for 3 components, with cross-validated R{sup 2} of 0.73), using the SYBYL and GOLPE programs. A pharmacophoric map was generated to locate steric and electrostatic interactions between theophylline and the RNA binding site. This information was used to identify putative functional groups of the binding pocket and to generate distance constraints. Based on a model for the secondary structure (Jenison et al., idem), the 3D structure of this RNA was then generated using the following method: each helical region of the RNA molecule was treated as a rigid body; single-stranded loops with specific end-to-end distances were generated. The structures of RNA-xanthine complexes were studied using a modified Monte Carlo algorithm. The detailed structure of an RNA-ligand complex model, as well as possible explanations for the theophylline selectivity will be discussed.
Serpa, Laura; Pavlis, Terry L.
1996-12-01
The accumulation of a large database on the timing and kinematics of late Cenozoic deformation in the Death Valley region of southeastern California indicates a complex three-dimensional history. On the basis of paleogeographic reconstructions we suggest the system was initiated as a localized pull-apart between two conjugate strike-slip faults, the Garlock and Furnace Creek faults, and evolved into a system characterized by distributed transtension related to the eastern California shear zone. Our reconstructions differ from previous models in the incorporation of significant vertical axis rotations of a number of crustal blocks to explain paleomagnetic data from the region. The model may resolve (1) a long-standing problem of the eastern termination of the Garlock fault which is explained here as a complex system of splays that initially terminated in the pull-apart between the Furnace Creek and Garlock systems; and (2) the complex architecture of the Black Mountains which is explained here in terms of initial extreme attenuation between the Garlock and Furnace Creek systems with overprinting by a fold and normal fault system that operated simultaneously as a result of distributed transtension. This model suggests much of the displacement field is taken up in rotations and translations, and the actual crustal thinning in our model is relatively small (50-66% of original thickness).
Gao, Bin; Wang, Lin; Han, Shuang; Pingguan-Murphy, Belinda; Zhang, Xiaohui; Xu, Feng
2016-08-01
Diabetes now is the most common chronic disease in the world inducing heavy burden for the people's health. Based on this, diabetes research such as islet function has become a hot topic in medical institutes of the world. Today, in medical institutes, the conventional experiment platform in vitro is monolayer cell culture. However, with the development of micro- and nano-technologies, several microengineering methods have been developed to fabricate three-dimensional (3D) islet models in vitro which can better mimic the islet of pancreases in vivo. These in vitro islet models have shown better cell function than monolayer cells, indicating their great potential as better experimental platforms to elucidate islet behaviors under both physiological and pathological conditions, such as the molecular mechanisms of diabetes and clinical islet transplantation. In this review, we present the state-of-the-art advances in the microengineering methods for fabricating microscale islet models in vitro. We hope this will help researchers to better understand the progress in the engineering 3D islet models and their biomedical applications such as drug screening and islet transplantation.
Laparoscopic acetabular fracture fixation after three-dimensional modelling and printing
Directory of Open Access Journals (Sweden)
Can-Jun Zeng
2017-01-01
Full Text Available Current surgical treatment of acetabular fractures is open reduction and internal fixation and requires a large incision resulting in considerable blood loss and a potentially long duration of recovery. We report a case of an acetabular fracture that received laparoscopic internal fixation after three-dimensional (3D modelling and printing of the acetabulum. A 43 year old male fell from a height of 3 m resulting in a right acetabulum anterior column fracture. Thin section computed tomography scanning with 0.6 mm increments and subsequent 3D reconstruction was performed, and a 3D model of the acetabulum and fracture was printed. The steel reconstruction plate was prebent in vivo and placed into the optimized position based on the 3D modelling and the optimized insert orientation and measured screw length were determined. The fracture was reduced and the plate placed laparoscopically without complications, and the patient had excellent functional recovery. Acetabular fractures are complex injuries, and while minimally invasive surgical techniques are used in many fields, they are not common for the treatment of acetabular fractures. 3D modelling is commonly used in medicine, and although 3D printing is used in some fields, it has not found widespread use in orthopedics.
A Fully Three Dimensional Semianalytical Model for Shale Gas Reservoirs with Hydraulic Fractures
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Yuwei Li
2018-02-01
Full Text Available Two challenges exist for modeling gas transport in shale. One is the existence of complex gas transport mechanisms, and the other is the impact of hydraulic fracture networks. In this study, a truly three dimensional semianalytical model was developed for shale gas reservoirs with hydraulic fractures of various shapes. Using the instantaneous point source solution, the pressure are solved for a bounded reservoir with fully 3D, partially penetrated hydraulic fractures of different strike angles and dip angles. The fractures could have various shapes such as rectangles, disks and ellipses. The shale gas diffusion equations considers complex transport mechanism such as gas slippage and gas diffusion. This semianalytical model is verified with a commercial software and an analytical method for single fully penetrated rectangle fracture, and the production results of shale gas are consistent. The impacts of fracture height and strike angles are investigated by five systematically constructed models. The comparison shows that the production increases proportionally with the fracture height, and decreases with the increase of strike angles. The method proposed in this study could also be applied in well testing to analyze the reservoir properties and used to forecast the production for tight oil and conventional resources.
A three-dimensional water quality model and its application to Jiaozhou Bay, China
Zhang, Yan; Sun, Ying-lan; Yu, Jing; Yuan, Dao-wei; Zhang, Rui-jin
2012-12-01
A three-dimensional coupled physical and water quality model was developed and applied to the Jiaozhou Bay to study water quality involving nutrients, biochemical oxygen demand, dissolved oxygen, and phytoplankton that are closely related to eutrophication process. The physical model is a modified ECOM-si version with inclusion of flooding/draining processes over the intertidal zone. The water quality model is based on WASP5 which quantifies processes governing internal nutrients cycling, dissolved oxygen balance and phytoplankton growth. The model was used to simulate the spatial distribution and the temporal variation of water quality in the Jiaozhou Bay for the period of May 2005 to May 2006. In addition, the effect of reduction of riverine nutrients load was simulated and evaluated. The simulated results show that under the influence of nutrients discharged from river, the concentrations of nutrients and phytoplankton were higher in the northwest and northeast of the bay, and decreased from the inner bay to the outer. Affected by strong tidal mixing, the concentrations of all state variables were vertically homogeneous except in the deeper regions where a small gradient was found. Obvious seasonal variation of phytoplankton biomass was found, which exhibited two peaks in March and July, respectively. The variation of riverine waste loads had remarkable impact on nutrients concentration in coastal areas, but slightly altered the distribution in the center of the bay.
Effective viscosity of a suspension of flagellar-beating microswimmers: Three-dimensional modeling.
Jibuti, Levan; Zimmermann, Walter; Rafaï, Salima; Peyla, Philippe
2017-11-01
Micro-organisms usually can swim in their liquid environment by flagellar or ciliary beating. In this numerical work, we analyze the influence of flagellar beating on the orbits of a swimming cell in a shear flow. We also calculate the effect of the flagellar beating on the rheology of a dilute suspension of microswimmers. A three-dimensional model is proposed for Chlamydomonas Reinhardtii swimming with a breaststroke-like beating of two anterior flagella modeled by two counter-rotating fore beads. The active swimmer model reveals unusual angular orbits in a linear shear flow. Namely, the swimmer sustains orientations transiently across the flow. Such behavior is a result of the interplay between shear flow and the swimmer's periodic beating motion of flagella, which exert internal torques on the cell body. This peculiar behavior has some significant consequences on the rheological properties of the suspension. We calculate Einstein's viscosity of the suspension composed of such isolated modeled microswimmers (dilute case) in a shear flow. We use numerical simulations based on a Rotne-Prager-like approximation for hydrodynamic interaction between simplified flagella and the cell body. The results show an increased intrinsic viscosity for active swimmer suspensions in comparison to nonactive ones as well as a shear thinning behavior in accordance with previous experimental measurements [Phys. Rev. Lett. 104, 098102 (2010)10.1103/PhysRevLett.104.098102].
Virtual cerebral ventricular system: an MR-based three-dimensional computer model.
Adams, Christina M; Wilson, Timothy D
2011-01-01
The inherent spatial complexity of the human cerebral ventricular system, coupled with its deep position within the brain, poses a problem for conceptualizing its anatomy. Cadaveric dissection, while considered the gold standard of anatomical learning, may be inadequate for learning the anatomy of the cerebral ventricular system; even with intricate dissection, ventricular structures remain difficult to observe. Three-dimensional (3D) computer reconstruction of the ventricular system offers a solution to this problem. This study aims to create an accurate 3D computer reconstruction of the ventricular system with surrounding structures, including the brain and cerebellum, using commercially available 3D rendering software. Magnetic resonance imaging (MRI) scans of a male cadaver were segmented using both semiautomatic and manual tools. Segmentation involves separating voxels of different grayscale values to highlight specific neural structures. User controls enable adding or removing of structures, altering their opacity, and making cross-sectional slices through the model to highlight inner structures. Complex physiologic concepts, such as the flow of cerebrospinal fluid, are also shown using the 3D model of the ventricular system through a video animation. The model can be projected stereoscopically, to increase depth perception and to emphasize spatial relationships between anatomical structures. This model is suited for both self-directed learning and classroom teaching of the 3D anatomical structure and spatial orientation of the ventricles, their connections, and their relation to adjacent neural and skeletal structures. Copyright © 2011 American Association of Anatomists.
Three-dimensional brain arteriovenous malformation models for clinical use and resident training.
Dong, Mengqi; Chen, Guangzhong; Li, Jianyi; Qin, Kun; Ding, Xiaowen; Peng, Chao; Zhou, Dong; Lin, Xiaofeng
2018-01-01
To fabricate three-dimensional (3D) models of brain arteriovenous malformation (bAVM) and report our experience with customized 3D printed models of patients with bAVM as an educational and clinical tool for patients, doctors, and surgical residents. Using computerized tomography angiography (CTA) or digital subtraction angiography (DSA) images, the rapid prototyping process was completed with specialized software and "in-house" 3D printing service. Intraoperative validation of model fidelity was performed by comparing to DSA images of the same patient during the endovascular treatment process. 3D bAVM models were used for preoperative patient education and consultation, surgical planning, and resident training. 3D printed bAVM models were successful made. By neurosurgeons' evaluation, the printed models precisely replicated the actual bAVM structure of the same patients (n = 7, 97% concordance, range 95%-99% with average of 3D models was associated shorter time for preoperative patient education and consultation, higher acceptable of the procedure for patients and relatives, shorter time between obtaining intraoperative DSA data and the start of endovascular treatment. Thirty surgical residents from residency programs tested the bAVM models and provided feedback on their resemblance to real bAVM structures and the usefulness of printed solid model as an educational tool. Patient-specific 3D printed models of bAVM can be constructed with high fidelity. 3D printed bAVM models were proven to be helpful in preoperative patient consultation, surgical planning, and resident training. Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.
Yang, W.; Kobayashi, H.; Kondoh, A.
2016-12-01
Three-dimensional (3-D) Monte Carlo (MC)-based radiative transfer (RT) models can simulate highly detailed forest environments, and have produced simulations that agree well with observations; thus, they are routinely used for benchmarking in intercomparisons of RT models. However, MC-based RT models have not been widely applied to the development of inversion algorithms for generating global remote sensing products of forests, due mainly to the difficulties in obtaining realistic forest structures for a variety of forest biomes. In this study, we developed a Forest Structure Dynamics Model (FSDM) to facilitate the application of MC-based RT models to global forests. In this model, the tree architectures are determined based on allometric equations, and the tree locations within a study domain are determined by statistical distributions. The performance of the FSDM was evaluated using field measurements of forest landscapes at two sites located at Järvselja, Estonia and the Poker Flat Research Range (PFRR), USA, respectively. The bidirectional reflectance factor (BRF) for the two study sites was simulated by an MC-based RT model, based on the measured forest stands and modeled stands from the FSDM. A comparison of the results demonstrated that the simulated BRF based on the measured forest stands agreed well with the simulated BRF based on the modeled stands from the FSDM for the two study sites. The applicability of the FSDM to a leaf area index (LAI) retrieval algorithm was also verified using simulations from the MC-based RT model. The results indicate that the FSDM can provide reasonable forest structures to drive 3-D canopy RT models, with no loss of simulation accuracy. When combined with several existing field data sets and satellite products, the FSDM can be used to generate a typical stand structure database for global forest biomes.
Three-dimensional semi-idealized model for estuarine turbidity maxima in tidally dominated estuaries
Kumar, Mohit; Schuttelaars, Henk M.; Roos, Pieter C.
2017-05-01
We develop a three-dimensional idealized model that is specifically aimed at gaining insight in the physical mechanisms resulting in the formation of estuarine turbidity maxima in tidally dominated estuaries. First, the three-dimensional equations for water motion and suspended sediment concentration together with the so-called morphodynamic equilibrium condition, are scaled. Next, surface elevation, velocity and sediment concentration are expanded in a small parameter ɛ =AbarM2 / H , where AbarM2 is the mean amplitude of the M2 tide and H is the mean water depth at the seaward side. This results in a system of equations at each order in this small parameter. This ordering allows solving for the vertical structure of the velocity and suspended sediment concentration, independently of the horizontal dimension. After obtaining these vertical structures, the horizontal dependencies of the physical variables follow from solving a two-dimensional elliptic partial differential equation for the surface elevation. The availability of fine sediments in the estuary follows from a two-dimensional elliptic partial differential equation which results from requiring the system to be in morphodynamic equilibrium, and prescribing the total amount of easily erodible sediments available in the estuary. These elliptic equations for the surface elevation and sediment availability are solved numerically using the finite element method with cubic polynomials as basis functions. As a first application, the model is applied to the Ems estuary using a simplified geometry and bathymetric profiles characteristic for the years 1980 and 2005. The availability of fine sediments and location of maximum concentration are investigated for different lateral depth profiles. In the first experiment, a uniform lateral depth is considered. In this case, both the sediment availability and suspended sediment concentration are, as expected, uniform in the lateral direction. In 1980, the sediment is
Tan, S; Hu, A; Wilson, T; Ladak, H; Haase, P; Fung, K
2012-04-01
(1) To investigate the efficacy of a computer-generated three-dimensional laryngeal model for laryngeal anatomy teaching; (2) to explore the relationship between students' spatial ability and acquisition of anatomical knowledge; and (3) to assess participants' opinion of the computerised model. Forty junior doctors were randomised to undertake laryngeal anatomy study supplemented by either a three-dimensional computer model or two-dimensional images. Outcome measurements comprised a laryngeal anatomy test, the modified Vandenberg and Kuse mental rotation test, and an opinion survey. Mean scores ± standard deviations for the anatomy test were 15.7 ± 2.0 for the 'three dimensions' group and 15.5 ± 2.3 for the 'standard' group (p = 0.7222). Pearson's correlation between the rotation test scores and the scores for the spatial ability questions in the anatomy test was 0.4791 (p = 0.086, n = 29). Opinion survey answers revealed significant differences in respondents' perceptions of the clarity and 'user friendliness' of, and their preferences for, the three-dimensional model as regards anatomical study. The three-dimensional computer model was equivalent to standard two-dimensional images, for the purpose of laryngeal anatomy teaching. There was no association between students' spatial ability and functional anatomy learning. However, students preferred to use the three-dimensional model.
Directory of Open Access Journals (Sweden)
Akimov Pavel Alekseevich
2012-10-01
Full Text Available The proposed paper covers the operator-related formulation of the eigenvalue problem of analysis of a three-dimensional structure that has piecewise-constant physical and geometrical parameters alongside the so-called basic direction within the framework of a discrete-continual approach (a discrete-continual finite element method, a discrete-continual variation method. Generally, discrete-continual formulations represent contemporary mathematical models that become available for computer implementation. They make it possible for a researcher to consider the boundary effects whenever particular components of the solution represent rapidly varying functions. Another feature of discrete-continual methods is the absence of any limitations imposed on lengths of structures. The three-dimensional problem of elasticity is used as the design model of a structure. In accordance with the so-called method of extended domain, the domain in question is embordered by an extended one of an arbitrary shape. At the stage of numerical implementation, relative key features of discrete-continual methods include convenient mathematical formulas, effective computational patterns and algorithms, simple data processing, etc. The authors present their formulation of the problem in question for an isotropic medium with allowance for supports restrained by elastic elements while standard boundary conditions are also taken into consideration.
Three-dimensional point-cloud room model in room acoustics simulations
DEFF Research Database (Denmark)
Markovic, Milos; Olesen, Søren Krarup; Hammershøi, Dorte
2013-01-01
acquisition and its representation with a 3D point-cloud model, as well as utilization of such a model for the room acoustics simulations. A room is scanned with a commercially available input device (Kinect for Xbox360) in two different ways; the first one involves the device placed in the middle of the room...... to build a 3D point-cloud model of the room. Several models are created to meet requirements of different room acoustics simulation algorithms: plane fitting and uniform voxel grid for geometric methods and triangulation mesh for the numerical methods. Advantages of the proposed method over the traditional...
Three-dimensional point-cloud room model for room acoustics simulations
DEFF Research Database (Denmark)
Markovic, Milos; Olesen, Søren Krarup; Hammershøi, Dorte
2013-01-01
acquisition and its representation with a 3D point-cloud model, as well as utilization of such a model for the room acoustics simulations. A room is scanned with a commercially available input device (Kinect for Xbox360) in two different ways; the first one involves the device placed in the middle of the room...... to build a 3D point-cloud model of the room. Several models are created to meet requirements of different room acoustics simulation algorithms: plane fitting and uniform voxel grid for geometric methods and triangulation mesh for the numerical methods. Advantages of the proposed method over the traditional...
Moeck, Christian; Affolter, Annette; Radny, Dirk; Dressmann, Horst; Auckenthaler, Adrian; Huggenberger, Peter; Schirmer, Mario
2018-02-01
A three-dimensional groundwater model was used to improve water resource management for a study area in north-west Switzerland, where drinking-water production is close to former landfills and industrial areas. To avoid drinking-water contamination, artificial groundwater recharge with surface water is used to create a hydraulic barrier between the contaminated sites and drinking-water extraction wells. The model was used for simulating existing and proposed water management strategies as a tool to ensure the utmost security for drinking water. A systematic evaluation of the flow direction between existing observation points using a developed three-point estimation method for a large number of scenarios was carried out. It is demonstrated that systematically applying the developed methodology helps to identify vulnerable locations which are sensitive to changing boundary conditions such as those arising from changes to artificial groundwater recharge rates. At these locations, additional investigations and protection are required. The presented integrated approach, using the groundwater flow direction between observation points, can be easily transferred to a variety of hydrological settings to systematically evaluate groundwater modelling scenarios.
Modeling and numerical analysis of a three-dimensional shape memory alloy shell structure
Zhao, Pengtao; Qiu, Jinhao; Ji, Hongli; Wang, Mingyi; Nie, Rui
2012-04-01
In this paper, modeling and numerical analysis of a three dimensional shell structure made of shape memory alloy (SMA) are introduced. As a new smart material, SMA material has been applied in many fields due to two significant macroscopic phenomena which are called the shape memory effect (SME) and pseudoelasticity. The material of SMA exhibits two-way shape memory effect (TWSME) after undergoing especial heat treatment and thermo-mechanical training. This work investigates the numerical simulation and application of the SMA component: SMA strip, which has been pre-curved in the room temperature. The component is expected to extend upon heating and shorten on cooling along the curve. Hence the shape memory effect can be used to change the shape of the structure. The return mapping algorithm of the 3-D SMA thermomechanical constitutive equations based on Boyd-Lagoudas model is used in the finite element analysis to describe the material features of the SMA. In this paper, the ABAQUS finite element program has been utilized with a user material subroutine (UMAT) which is written in the FORTRAN code for the modeling of the SMA strip. The SMA component which has a certain initial transformation strain can emerge considerable deflection during the reverse phase transformation inducing by the temperature.
In vitro three-dimensional cancer metastasis modeling: Past, present, and future
Wei-jing, Han; Wei, Yuan; Jiang-rui, Zhu; Qihui, Fan; Junle, Qu; Li-yu, Liu
2016-01-01
Metastasis is the leading cause of most cancer deaths, as opposed to dysregulated cell growth of the primary tumor. Molecular mechanisms of metastasis have been studied for decades and the findings have evolved our understanding of the progression of malignancy. However, most of the molecular mechanisms fail to address the causes of cancer and its evolutionary origin, demonstrating an inability to find a solution for complete cure of cancer. After being a neglected area of tumor biology for quite some time, recently several studies have focused on the impact of the tumor microenvironment on cancer growth. The importance of the tumor microenvironment is gradually gaining attention, particularly from the perspective of biophysics. In vitro three-dimensional (3-D) metastatic models are an indispensable platform for investigating the tumor microenvironment, as they mimic the in vivo tumor tissue. In 3-D metastatic in vitro models, static factors such as the mechanical properties, biochemical factors, as well as dynamic factors such as cell-cell, cell-ECM interactions, and fluid shear stress can be studied quantitatively. With increasing focus on basic cancer research and drug development, the in vitro 3-D models offer unique advantages in fundamental and clinical biomedical studies. Project supported by the National Basic Research Program of China (Grant No. 2013CB837200), the National Natural Science Foundation of China (Grant No. 11474345), and the Beijing Natural Science Foundation, China (Grant No. 7154221).
Individualizing Management of Complex Esophageal Pathology Using Three-Dimensional Printed Models.
Dickinson, Karen J; Matsumoto, Jane; Cassivi, Stephen D; Reinersman, J Matthew; Fletcher, Joel G; Morris, Jonathan; Wong Kee Song, Louis M; Blackmon, Shanda H
2015-08-01
In complex esophageal cases, conventional two-dimensional imaging is limited in demonstrating anatomic relationships. We describe the utility of three-dimensional (3D) printed models for complex patients to individualize care. Oral effervescent agents, with positive enteric contrast, distended the esophagus during computed tomography (CT) scanning to facilitate segmentation during post-processing. The CT data were segmented, converted into a stereolithography file, and printed using photopolymer materials. In 1 patient with a left pneumonectomy, aortic bypass, and esophageal diversion, 3D printing enabled visualization of the native esophagus and facilitated endoscopic mucosal resection, followed by hiatal dissection and division of the gastroesophageal junction as treatment. In a second patient, 3D printing allowed enhanced visualization of multiple esophageal diverticula, allowing for optimization of the surgical approach. Printing of 3D anatomic models in patients with complex esophageal pathology facilitates planning the optimal surgical approach and anticipating potential difficulties for the multidisciplinary team. These models are invaluable for patient education. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.
Experimental study and new three-dimensional kinetic modeling of foamy solution-gas drive processes.
Sun, Xiaofei; Zhang, Yanyu; Wang, Shilin; Song, Zhaoyao; Li, Peng; Wang, Changfa
2018-03-12
Foamy solution-gas drive processes in heavy oil reservoirs are very complex. The influence of some microscopic factors on this process is not fully understood due to limitations of traditional depletion tests. This study aims to investigate foamy solution-gas drive by experiments and simulations. First, the effects of the pressure depletion rate on critical gas saturation and foamy solution-gas drive processes were investigated by laboratory experiments. Second, a new three-dimensional foamy oil model that captures many important characteristics of foamy solution-gas drive, such as non-equilibrium behavior, gas evolution kinetics, and the effect of viscous forces on gas mobility, was developed. Last, the effects of some important parameters on foamy solution-gas drive were systematically investigated,and a model application was conducted in a typical foamy oil reservoir. The results indicate that the new model is capble of simulating many of the unusual behaviors observed in foamy solution-gas drive on a laboratory and field scales. High oil recoveries were obtained with a high oil viscosity, high depletion rate, long sandpack, and low solution gas-oil ratio. Foamy solution-gas drive processes are sensitive to the depletion rate, length, and critical gas saturation. The oil viscosity, solution GOR and diffusion coefficient are not sensitive factors.
Cytopede: a three-dimensional tool for modeling cell motility on a flat surface.
Herant, Marc; Dembo, Micah
2010-12-01
When cultured on flat surfaces, fibroblasts and many other cells spread to form thin lamellar sheets. Motion then occurs by extension of the sheet at the leading edge and retraction at the trailing edge. Comprehensive quantitative models of these phenomena have so far been lacking and to address this need, we have designed a three-dimensional code called Cytopede specialized for the simulation of the mechanical and signaling behavior of plated cells. Under assumptions by which the cytosol and the cytoskeleton are treated from a continuum mechanical perspective, Cytopede uses the finite element method to solve mass and momentum equations for each phase, and thus determine the time evolution of cellular models. We present the physical concepts that underlie Cytopede together with the algorithms used for their implementation. We then validate the approach by a computation of the spread of a viscous sessile droplet. Finally, to exemplify how Cytopede enables the testing of ideas about cell mechanics, we simulate a simple fibroblast model. We show how Cytopede allows computation, not only of basic characteristics of shape and velocity, but also of maps of cell thickness, cytoskeletal density, cytoskeletal flow, and substratum tractions that are readily compared with experimental data.
An Incompressible Three-Dimensional Multiphase Particle-in-Cell Model for Dense Particle Flows
Snider, D. M.
2001-07-01
A three-dimensional, incompressible, multiphase particle-in-cell method is presented for dense particle flows. The numerical technique solves the governing equations of the fluid phase using a continuum model and those of the particle phase using a Lagrangian model. Difficulties associated with calculating interparticle interactions for dense particle flows with volume fractions above 5% have been eliminated by mapping particle properties to an Eulerian grid and then mapping back computed stress tensors to particle positions. A subgrid particle, normal stress model for discrete particles which is robust and eliminates the need for an implicit calculation of the particle normal stress on the grid is presented. Interpolation operators and their properties are defined which provide compact support, are conservative, and provide fast solution for a large particle population. The solution scheme allows for distributions of types, sizes, and density of particles, with no numerical diffusion from the Lagrangian particle calculations. Particles are implicitly coupled to the fluid phase, and the fluid momentum and pressure equations are implicitly solved, which gives a robust solution.
McKenna, M. H.; Alter, R. E.; Swearingen, M. E.; Wilson, D. K.
2017-12-01
Many larger sources, such as volcanic eruptions and nuclear detonations, produce infrasound (acoustic waves with a frequency lower than humans can hear, namely 0.1-20 Hz) that can propagate over global scales. But many smaller infrastructure sources, such as bridges, dams, and buildings, also produce infrasound, though with a lower amplitude that tends to propagate only over regional scales (up to 150 km). In order to accurately calculate regional-scale infrasound propagation, we have incorporated high-resolution, three-dimensional forecasts from the Weather Research and Forecasting (WRF) meteorological model into a signal propagation modeling system called Environmental Awareness for Sensor and Emitter Employment (EASEE), developed at the US Army Engineer Research and Development Center. To quantify the improvement of infrasound propagation predictions with more realistic weather data, we conducted sensitivity studies with different propagation ranges and horizontal resolutions and compared them to default predictions with no weather model data. We describe the process of incorporating WRF output into EASEE for conducting these acoustic propagation simulations and present the results of the aforementioned sensitivity studies.
Three-dimensional tsunami propagation simulations using an unstructured mesh finite element model
Oishi, Yusuke; Piggott, Matthew D.; Maeda, Takuto; Kramer, Stephan C.; Collins, Gareth S.; Tsushima, Hiroaki; Furumura, Takashi
2013-06-01
Large-scale tsunami propagation simulations from the fault region to the coast are conducted using a three-dimensional (3-D) parallel unstructured mesh finite element code (Fluidity-ICOM). Unlike conventional 2-D approximation models, our tsunami model solves the full 3-D incompressible Navier-Stokes (NS) equations. The model is tested against analytical solutions to simple dispersive wave propagation problems. Comparisons of our 3-D NS model results with those from linear shallow water and linear dispersive wave models demonstrate that the 3-D NS model simulates the dispersion of very short wavelength components more accurately than the 2-D models. This improved accuracy is achieved using only a small number (three to five) of vertical layers in the mesh. The numerical error in the wave velocity compared with the linear wave theory is less than 3% up to kH = 40, where k is the wave number and H is the sea depth. The same 2-D and 3-D models are also used to simulate two earthquake-generated tsunamis off the coast of Japan: the 2004 off Kii peninsula and the 2011 off Tohoku tsunamis. The linear dispersive and NS models showed good agreement in the leading waves but differed especially in their near-source, short wavelength dispersive wave components. This is consistent with the results from earlier tests, suggesting that the 3-D NS simulations are more accurate. The computational performance on a parallel computer showed good scalability up to 512 cores. By using a combination of unstructured meshes and high-performance computers, highly accurate 3-D tsunami simulations can be conducted in a practical timescale.
Ngwira, Chigomezyo M.; Pulkkinen, Antti; Kuznetsova, Maria M.; Glocer, Alex
2014-06-01
There is a growing concern over possible severe societal consequences related to adverse space weather impacts on man-made technological infrastructure. In the last two decades, significant progress has been made toward the first-principles modeling of space weather events, and three-dimensional (3-D) global magnetohydrodynamics (MHD) models have been at the forefront of this transition, thereby playing a critical role in advancing our understanding of space weather. However, the modeling of extreme space weather events is still a major challenge even for the modern global MHD models. In this study, we introduce a specially adapted University of Michigan 3-D global MHD model for simulating extreme space weather events with a Dst footprint comparable to the Carrington superstorm of September 1859 based on the estimate by Tsurutani et. al. (2003). Results are presented for a simulation run with "very extreme" constructed/idealized solar wind boundary conditions driving the magnetosphere. In particular, we describe the reaction of the magnetosphere-ionosphere system and the associated induced geoelectric field on the ground to such extreme driving conditions. The model setup is further tested using input data for an observed space weather event of Halloween storm October 2003 to verify the MHD model consistence and to draw additional guidance for future work. This extreme space weather MHD model setup is designed specifically for practical application to the modeling of extreme geomagnetically induced electric fields, which can drive large currents in ground-based conductor systems such as power transmission grids. Therefore, our ultimate goal is to explore the level of geoelectric fields that can be induced from an assumed storm of the reported magnitude, i.e., Dst˜=-1600 nT.
Rastigejev, Y.; Semakin, A. N.
2013-12-01
Accurate numerical simulations of global scale three-dimensional atmospheric chemical transport models (CTMs) are essential for studies of many important atmospheric chemistry problems such as adverse effect of air pollutants on human health, ecosystems and the Earth's climate. These simulations usually require large CPU time due to numerical difficulties associated with a wide range of spatial and temporal scales, nonlinearity and large number of reacting species. In our previous work we have shown that in order to achieve adequate convergence rate and accuracy, the mesh spacing in numerical simulation of global synoptic-scale pollution plume transport must be decreased to a few kilometers. This resolution is difficult to achieve for global CTMs on uniform or quasi-uniform grids. To address the described above difficulty we developed a three-dimensional Wavelet-based Adaptive Mesh Refinement (WAMR) algorithm. The method employs a highly non-uniform adaptive grid with fine resolution over the areas of interest without requiring small grid-spacing throughout the entire domain. The method uses multi-grid iterative solver that naturally takes advantage of a multilevel structure of the adaptive grid. In order to represent the multilevel adaptive grid efficiently, a dynamic data structure based on indirect memory addressing has been developed. The data structure allows rapid access to individual points, fast inter-grid operations and re-gridding. The WAMR method has been implemented on parallel computer architectures. The parallel algorithm is based on run-time partitioning and load-balancing scheme for the adaptive grid. The partitioning scheme maintains locality to reduce communications between computing nodes. The parallel scheme was found to be cost-effective. Specifically we obtained an order of magnitude increase in computational speed for numerical simulations performed on a twelve-core single processor workstation. We have applied the WAMR method for numerical
Three-dimensional Subsurface Geological Modeling of the Western Osaka Plane based on Borehole Data
Nonogaki, S.; Masumoto, S.; Nemoto, T.
2012-12-01
Three-dimensional (3D) geological model of subsurface structure plays an important role in developing infrastructures. In particular, the 3D geological model in urban area is quite helpful to solve social problems such as underground utilization, environmental preservation, and disaster assessment. Over the past few years, many studies have been made on algorithms for 3D geological modeling. However, most of them have given little attention to objectivity of the model and traceability of modeling procedures. The purpose of this study is to develop an algorithm for constructing a 3D geological model objectively and for maintaining high-traceability of modeling procedures. For the purpose of our work, we proposed a new algorithm for 3D geological modeling using gridded geological boundary surfaces and the "logical model of geologic structure". The geological boundary surface is given by a form of Digital Elevation Model (DEM). The DEM is generated based on geological information such as elevation, strike and dip by using a unique spline-fitting method. The logical model of geological structure is a mathematical model that defines a positional relation between geological boundary surfaces and geological units. The model is objectively given by recurrence formula derived from a sequence of geological events arranged in chronological order. We applied the proposed algorithm into constructing a 3D subsurface geological model of the western Osaka Plane, southwest Japan. The data used for 3D geological modeling is a set of borehole data provided by Osaka City and Kansai Geoinformatics Agency. As a result, we constructed a 3D model consistent with the subjective model reported in other studies. In addition, all information necessary for modeling, such as the used geological information, the parameters of surface fitting, and the logical model, was stored in text files. In conclusion, we can not only construct 3D geological model objectively but also maintain high
Three-dimensional printing of anatomically accurate, patient specific intracranial aneurysm models.
Anderson, Jeff R; Thompson, Walker L; Alkattan, Abdulaziz K; Diaz, Orlando; Klucznik, Richard; Zhang, Yi J; Britz, Gavin W; Grossman, Robert G; Karmonik, Christof
2016-05-01
To develop and validate a method for creating realistic, patient specific replicas of cerebral aneurysms by means of fused deposition modeling. The luminal boundaries of 10 cerebral aneurysms, together with adjacent proximal and distal sections of the parent artery, were segmented based on DSA images, and corresponding virtual three-dimensional (3D) surface reconstructions were created. From these, polylactic acid and MakerBot Flexible Filament replicas of each aneurysm were created by means of fused deposition modeling. The accuracy of the replicas was assessed by quantifying statistical significance in the variations of their inner dimensions relative to 3D DSA images. Feasibility for using these replicas as flow phantoms in combination with phase contrast MRI was demonstrated. 3D printed aneurysm models were created for all 10 subjects. Good agreement was seen between the models and the source anatomy. Aneurysm diameter measurements of the printed models and source images correlated well (r=0.999; pmodels, respectively. 3D printed models could be imaged with flow via MRI. The 3D printed aneurysm models presented were accurate and were able to be produced inhouse. These models can be used for previously cited applications, but their anatomical accuracy also enables their use as MRI flow phantoms for comparison with ongoing studies of computational fluid dynamics. Proof of principle imaging experiments confirm MRI flow phantom utility. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/
Fan, Xin-Gang; Mi, Wen-Bao; Ma, Zhen-Ning
2015-02-01
For deep analysis on the regional environmental economic system, the paper analyzes the mutual relation of regional economy development, environmental quality, environmental pollution, and builds the theoretical basis. Then, the economy-pollution-environment quality three-dimensional coupling evaluation model for district is constructed. It includes economic development level index, environmental pollution index, and environmental quality index. The model is a cube, which has spatialization and visualization characteristics. The model includes 8 sub cubes, which expresses 8 types of state, e. g. low pollution-inferior quality-low level of economic development etc. The model can be used to evaluate the status of region, divide development phase, analyze evolution trend etc. It has two ways including relative meaning evaluation (RME) and absolute meaning evaluation (AME). Based on the model, Yinchuan City in the Ningxia Hui Autonomous Region is used as an example for the empirical study. Using RME, compared with Guangzhou city, The result shows that the Yinchuan City has been a high pollution-low quality-low level of economic development state for a long period during 1996-2010. After 2007, the state changed to a high pollution-high quality-low level of economic development. Now, the environmental quality of Yinchuan city gets better, but pollutant discharge pressure is high, and tends to be the break point of high environment quality and low environment. With AME, using national standard, the Yinchuan City remains a high pollution-low quality-low level of economic development state during 1996-2010. Empirical research verifies that different target reference areas and relevant national standards have different main parameters, the evaluating result has an flexible range. The dimensionless data enhances the coupling of index. The data position in model increases the visibility to the environmental management decisions. The model improves mismatches of calculated data
Three-dimensional modelling of leachate recirculation using vertical wells in bioreactor landfills.
Feng, Shi-Jin; Chen, Zheng-Wei; Cao, Ben-Yi
2016-12-01
Bioreactor landfills use leachate recirculation to enhance the biodegradation of municipal solid waste and accelerate landfill stabilisation, which can provide significant environmental and economic benefits. Vertical wells are operated as a major method for leachate recirculation systems. The objectives of this article are to analyse the leachate migration in bioreactor landfills using vertical wells and to offer theoretical basis for the design of leachate recirculation systems. A three-dimensional numerical model was built using FLAC-3D, and this model can consider the saturated and unsaturated flow of leachate within anisotropic waste to reflect the actual conditions. First, main influence factors of leachate migration were analysed, including the vertical well height, hydraulic conductivity, and anisotropic coefficient, in a single-well recirculation system. Then, the effects of different configurations of a group-well system were studied and the optimal well spacing was obtained. Some key design parameters (e.g. the recirculation flow rate, volume of impact zone, radius of impact zone and time to reach steady state) were also evaluated. The results show that the hydraulic conductivity has a great impact on the optimal height of vertical wells and uniform configuration is the best option in terms of both volume of impact zone and time to reach steady state. © The Author(s) 2016.
Three-Dimensional Mathematical Model of Oxygen Transport Behavior in Electroslag Remelting Process
Huang, Xuechi; Li, Baokuan; Liu, Zhongqiu
2018-04-01
A transient three-dimensional model has been proposed to investigate the oxygen transport behavior in electroslag remelting process. The electromagnetism, heat transfer, multiphase flow, and species transport were calculated simultaneously by finite volume method. The volume of fluid approach was adopted to trace the metal-slag-air three-phase flow. Based on the necessary thermodynamics of oxygen transport behavior, a kinetic model was established to predict the mass source terms in species transport equation. The kinetic correction factor was proposed to account for the effect of the oxide scale formed on the electrode on the FeO content in slag. Finally, the effect of applied current on the oxygen transfer was studied. The predicted result agrees well with the measured data when the kinetic correction factor is set to be 0.5. The temperature distribution that affects the thermodynamics differs at the interfaces. The oxygen in air is absorbed into slag due to the oxidation at the slag/air interface. The Fe2O3 in slag and the oxide scale contribute to the increase of FeO content in slag, and the latter one plays the leading role. The oxygen transfer from slag to metal mainly occurs during the formation of the droplet at the slag/metal droplet interface. With the current increasing from 1200 to 1800 A, the oxygen content increases from 76.4 to 89.8 ppm, and then slightly declines to 89.2 ppm when the current increases to 2100 A.
Directory of Open Access Journals (Sweden)
Suzhi Xiao
2016-04-01
Full Text Available In order to acquire an accurate three-dimensional (3D measurement, the traditional fringe projection technique applies complex and laborious procedures to compensate for the errors that exist in the vision system. However, the error sources in the vision system are very complex, such as lens distortion, lens defocus, and fringe pattern nonsinusoidality. Some errors cannot even be explained or rendered with clear expressions and are difficult to compensate directly as a result. In this paper, an approach is proposed that avoids the complex and laborious compensation procedure for error sources but still promises accurate 3D measurement. It is realized by the mathematical model extension technique. The parameters of the extended mathematical model for the ’phase to 3D coordinates transformation’ are derived using the least-squares parameter estimation algorithm. In addition, a phase-coding method based on a frequency analysis is proposed for the absolute phase map retrieval to spatially isolated objects. The results demonstrate the validity and the accuracy of the proposed flexible fringe projection vision system on spatially continuous and discontinuous objects for 3D measurement.
Xiao, Suzhi; Tao, Wei; Zhao, Hui
2016-04-28
In order to acquire an accurate three-dimensional (3D) measurement, the traditional fringe projection technique applies complex and laborious procedures to compensate for the errors that exist in the vision system. However, the error sources in the vision system are very complex, such as lens distortion, lens defocus, and fringe pattern nonsinusoidality. Some errors cannot even be explained or rendered with clear expressions and are difficult to compensate directly as a result. In this paper, an approach is proposed that avoids the complex and laborious compensation procedure for error sources but still promises accurate 3D measurement. It is realized by the mathematical model extension technique. The parameters of the extended mathematical model for the 'phase to 3D coordinates transformation' are derived using the least-squares parameter estimation algorithm. In addition, a phase-coding method based on a frequency analysis is proposed for the absolute phase map retrieval to spatially isolated objects. The results demonstrate the validity and the accuracy of the proposed flexible fringe projection vision system on spatially continuous and discontinuous objects for 3D measurement.
Three-Dimensional Mathematical Model of Oxygen Transport Behavior in Electroslag Remelting Process
Huang, Xuechi; Li, Baokuan; Liu, Zhongqiu
2017-12-01
A transient three-dimensional model has been proposed to investigate the oxygen transport behavior in electroslag remelting process. The electromagnetism, heat transfer, multiphase flow, and species transport were calculated simultaneously by finite volume method. The volume of fluid approach was adopted to trace the metal-slag-air three-phase flow. Based on the necessary thermodynamics of oxygen transport behavior, a kinetic model was established to predict the mass source terms in species transport equation. The kinetic correction factor was proposed to account for the effect of the oxide scale formed on the electrode on the FeO content in slag. Finally, the effect of applied current on the oxygen transfer was studied. The predicted result agrees well with the measured data when the kinetic correction factor is set to be 0.5. The temperature distribution that affects the thermodynamics differs at the interfaces. The oxygen in air is absorbed into slag due to the oxidation at the slag/air interface. The Fe2O3 in slag and the oxide scale contribute to the increase of FeO content in slag, and the latter one plays the leading role. The oxygen transfer from slag to metal mainly occurs during the formation of the droplet at the slag/metal droplet interface. With the current increasing from 1200 to 1800 A, the oxygen content increases from 76.4 to 89.8 ppm, and then slightly declines to 89.2 ppm when the current increases to 2100 A.
Continuous data assimilation for the three-dimensional Brinkman–Forchheimer-extended Darcy model
Markowich, Peter A.
2016-03-09
In this paper we introduce and analyze an algorithm for continuous data assimilation for a three-dimensional Brinkman-Forchheimer-extended Darcy (3D BFeD) model of porous media. This model is believed to be accurate when the flow velocity is too large for Darcy\\'s law to be valid, and additionally the porosity is not too small. The algorithm is inspired by ideas developed for designing finite-parameters feedback control for dissipative systems. It aims to obtain improved estimates of the state of the physical system by incorporating deterministic or noisy measurements and observations. Specifically, the algorithm involves a feedback control that nudges the large scales of the approximate solution toward those of the reference solution associated with the spatial measurements. In the first part of the paper, we present a few results of existence and uniqueness of weak and strong solutions of the 3D BFeD system. The second part is devoted to the convergence analysis of the data assimilation algorithm. © 2016 IOP Publishing Ltd & London Mathematical Society.
Methylquercetins stimulate melanin biosynthesis in a three-dimensional skin model.
Yamauchi, Kosei; Mitsunaga, Tohru
2018-02-13
In a previous study, we found that both synthetic 3-O-methylquercetin (3MQ) and 3,4',7-O-trimethylquercetin (34'7TMQ) increased extracellular melanin content. 34'7TMQ increased the activity of melanogenic enzymes by stimulating the p38 pathway and the expression of microphthalmia-associated transcription factor (MITF). In contrast, 3MQ increased the activity of melanogenic enzymes without the involvement of MITF, which suggests that 3MQ inhibits the degradation of melanogenic enzymes. In the present study, we investigated the effects of 3MQ and 34'7TMQ on melanogenesis in normal human melanocytes and using a commercial three-dimensional (3D) skin model system. Both 3MQ and 34'7TMQ elongated the dendrites of normal human melanocytes from a Caucasian donor, but did not stimulate melanogenesis in the melanocytes. In the 3D skin model, which included melanocytes from an Asian donor, 3MQ and 34'7TMQ increased and elongated the melanocytes and showed a tendency to stimulate melanogenesis. These results suggest that 3MQ and 34'7TMQ could be put to practical use in skin care products and agents aimed at preventing hair graying.
Dong, Erbao; Zhao, Zuhua; Wang, Minjie; Xie, Yanjun; Li, Shidi; Shao, Pengfei; Cheng, Liuquan; Xu, Ronald X.
2015-12-01
Biomedical optical devices are widely used for clinical detection of various tissue anomalies. However, optical measurements have limited accuracy and traceability, partially owing to the lack of effective calibration methods that simulate the actual tissue conditions. To facilitate standardized calibration and performance evaluation of medical optical devices, we develop a three-dimensional fuse deposition modeling (FDM) technique for freeform fabrication of tissue-simulating phantoms. The FDM system uses transparent gel wax as the base material, titanium dioxide (TiO2) powder as the scattering ingredient, and graphite powder as the absorption ingredient. The ingredients are preheated, mixed, and deposited at the designated ratios layer-by-layer to simulate tissue structural and optical heterogeneities. By printing the sections of human brain model based on magnetic resonance images, we demonstrate the capability for simulating tissue structural heterogeneities. By measuring optical properties of multilayered phantoms and comparing with numerical simulation, we demonstrate the feasibility for simulating tissue optical properties. By creating a rat head phantom with embedded vasculature, we demonstrate the potential for mimicking physiologic processes of a living system.
Directory of Open Access Journals (Sweden)
L. Sun
2007-10-01
Full Text Available In order to study the filter effect of the background winds on the propagation of gravity waves, a three-dimensional transfer function model is developed on the basis of the complex dispersion relation of internal gravity waves in a stratified dissipative atmosphere with background winds. Our model has successfully represented the main results of the ray tracing method, e.g. the trend of the gravity waves to travel in the anti-windward direction. Furthermore, some interesting characteristics are manifest as follows: (1 The method provides the distribution characteristic of whole wave fields which propagate in the way of the distorted concentric circles at the same altitude under the control of the winds. (2 Through analyzing the frequency and wave number response curve of the transfer function, we find that the gravity waves in a wave band of about 15–30 min periods and of about 200–400 km horizontal wave lengths are most likely to propagate to the 300-km ionospheric height. Furthermore, there is an obvious frequency deviation for gravity waves propagating with winds in the frequency domain. The maximum power of the transfer function with background winds is smaller than that without background winds. (3 The atmospheric winds may act as a directional filter that will permit gravity wave packets propagating against the winds to reach the ionospheric height with minimum energy loss.
In vitro ovarian cancer model based on three-dimensional agarose hydrogel
Directory of Open Access Journals (Sweden)
Guojie Xu
2014-01-01
Full Text Available To establish a typical tumor model of ovarian cancer which may be more representative and reliable than traditional monolayer culture and pellet, agarose was used as cell vehicle to engineering tumor. Selection of agarose is based on its successful application in tissue engineering with both amenable mechanical and biological properties. In this study, ovarian cancer cell line SKOV3 was encapsulated in agarose hydrogel with cell aggregates and two-dimensional culture as controls. In vitro cell proliferation was assessed by MTT and cell viability was examined at time points of 2, 4, and 6 days. The expression of tumor malignancy markers including matrix metalloproteinase 2, matrix metalloproteinase 9, hypoxia-inducible factor-1α, and vascular endothelial growth factor–A was assessed by real-time polymerase chain reaction. The results showed that cells proliferated more rapidly in three-dimensional agarose culture than controls. Furthermore, upregulation of matrix metalloproteinase 9 and matrix metalloproteinase 2 activity and increased expression of vascular endothelial growth factor–A and hypoxia-inducible factor-1α were shown in agarose-engineered tumors. All the evidences demonstrated that agarose may provide a more favorable environment for cancer cell growth, mimicking the in vivo environment for tumor generation. The novel in vitro tumor model may be useful for the further investigation of anticancer therapeutics.
Advanced three-dimensional thermal modeling of a baseline spent fuel repository
International Nuclear Information System (INIS)
Altenbach, T.J.; Lowry, W.E.
1980-01-01
A three-dimensional thermal analysis using finite difference techniques was performed to determine the near-field response of a baseline spent fuel repository in a deep geologic salt medium. A baseline design incorporates previous thermal modeling experience and OWI recommendations for areal thermal loading in specifying the waste form properties, package details, and emplacement configuration. The base case in this thermal analysis considers one 10-year old PWR spent fuel assembly emplaced to yield a 36 kW/acre (8.9 W/m 2 ) loading. A unit cell model in an infinite array is used to simplify the problem and provide upper-bound temperatures. Boundary conditions are imposed which allow simulations to 1000 years. Variations studied include a comparison of ventilated and unventilated storage room conditions, emplacement packages with and without air gaps surrounding the canister, and room cool-down scenarios with ventilation following an unventilated state for retrieval purposes. It was found that at this low-power level, ventilating the emplacement room has an immediate cooling influence on the canister and effectively maintains the emplacement room floor near the temperature of the ventilating air
Modeling dense-colloid and virus cotransport in three-dimensional porous media.
Katzourakis, Vasileios E; Chrysikopoulos, Constantinos V
2015-10-01
A three-dimensional numerical model was developed to investigate the simultaneous transport (cotransport) of dense colloids and viruses in homogeneous, water saturated, porous media with horizontal uniform flow. The dense colloids are assumed to exist in two different phases: suspended in the aqueous phase, and attached reversibly and/or irreversibly onto the solid matrix. The viruses are assumed to exist in four different phases: suspended in aqueous phase, attached onto the solid matrix, attached onto suspended colloids, and attached onto colloids already attached onto the solid matrix. The viruses in each of the four phases are assumed to undergo inactivation with different rates. Moreover, the suspended dense colloids as well as viruses attached onto suspended dense colloids are assumed to exhibit a "restricted" settling velocity as a consequence of the gravitational force; whereas, viruses due to their small sizes and densities are assumed to have negligible "restricted" settling velocity. The governing differential equations were solved numerically with the finite difference schemes, implicitly or explicitly implemented. Model simulations have shown that the presence of dense colloid particles can either enhance or hinder the horizontal transport of viruses, but also can increase the vertical migration of viruses. Copyright © 2015 Elsevier B.V. All rights reserved.
Three-dimensional Cascaded Lattice Boltzmann Model for Thermal Convective Flows
Hajabdollahi, Farzaneh; Premnath, Kannan
2017-11-01
Fluid motion driven by thermal effects, such as due to buoyancy in differentially heated enclosures arise in several natural and industrial settings, whose understanding can be achieved via numerical simulations. Lattice Boltzmann (LB) methods are efficient kinetic computational approaches for coupled flow physics problems. In this study, we develop three-dimensional (3D) LB models based on central moments and multiple relaxation times for D3Q7 and D3Q15 lattices to solve the energy transport equations in a double distribution function approach. Their collision operators lead to a cascaded structure involving higher order terms resulting in improved stability. This is coupled to a central moment based LB flow solver with source terms. The new 3D cascaded LB models for the convective flows are first validated for natural convection of air driven thermally on two vertically opposite faces in a cubic cavity at different Rayleigh numbers against prior numerical and experimental data, which show good quantitative agreement. Then, the detailed structure of the 3D flow and thermal fields and the heat transfer rates at different Rayleigh numbers are analyzed and interpreted.
Verifying three-dimensional skull model reconstruction using cranial index of symmetry.
Directory of Open Access Journals (Sweden)
Woon-Man Kung
Full Text Available BACKGROUND: Difficulty exists in scalp adaptation for cranioplasty with customized computer-assisted design/manufacturing (CAD/CAM implant in situations of excessive wound tension and sub-cranioplasty dead space. To solve this clinical problem, the CAD/CAM technique should include algorithms to reconstruct a depressed contour to cover the skull defect. Satisfactory CAM-derived alloplastic implants are based on highly accurate three-dimensional (3-D CAD modeling. Thus, it is quite important to establish a symmetrically regular CAD/CAM reconstruction prior to depressing the contour. The purpose of this study is to verify the aesthetic outcomes of CAD models with regular contours using cranial index of symmetry (CIS. MATERIALS AND METHODS: From January 2011 to June 2012, decompressive craniectomy (DC was performed for 15 consecutive patients in our institute. 3-D CAD models of skull defects were reconstructed using commercial software. These models were checked in terms of symmetry by CIS scores. RESULTS: CIS scores of CAD reconstructions were 99.24±0.004% (range 98.47-99.84. CIS scores of these CAD models were statistically significantly greater than 95%, identical to 99.5%, but lower than 99.6% (p<0.001, p = 0.064, p = 0.021 respectively, Wilcoxon matched pairs signed rank test. These data evidenced the highly accurate symmetry of these CAD models with regular contours. CONCLUSIONS: CIS calculation is beneficial to assess aesthetic outcomes of CAD-reconstructed skulls in terms of cranial symmetry. This enables further accurate CAD models and CAM cranial implants with depressed contours, which are essential in patients with difficult scalp adaptation.
Gualtero, D F; Lafaurie, G I; Fontanilla, M R
2018-02-01
Epidemiological studies have established a clinical association between periodontal disease and atherosclerosis. Bacteremia and endotoxemia episodes in patients with periodontitis appear to link these two diseases by inducing a body-wide production of cardiovascular markers. The presence of oral bacteria in atherosclerotic lesions in patients with periodontitis suggests that bacteria, or their antigenic components, induce alterations in the endothelium associated with atherosclerosis. Therefore, a causal mechanism explaining the association between both diseases can be constructed using in vitro models. This review presents current experimental approaches based on in vitro cell models used to shed light on the mechanism by which periodontal pathogenic microorganisms, and their antigenic components, induce proatherosclerotic endothelial activity. Monolayer cultures of endothelial vascular or arterial cells have been used to assess periodontal pathogenic bacteria and their antigenic compounds and endothelial activation. However, these models are not capable of reflecting the physiological characteristics of the endothelium inside vascularized tissue. Therefore, the shift from two-dimensional (2D) cellular models toward three-dimensional (3D) models of endothelial cells resembling an environment close to the physiological environment of the endothelial cell within the endothelium is useful for evaluating the physiological relevance of results regarding the endothelial dysfunction induced by periodontopathogens that are currently obtained from 2D models. The use of in vitro 3D cellular models can also be relevant to the search for therapeutic agents for chronic inflammatory diseases such as atherosclerosis. Here, we present some strategies for the assembly of 3D cultures with endothelial cells, which is useful for the study of periodontopathogen-mediated disease. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Moeck, Christian; Affolter, Annette; Radny, Dirk; Auckenthaler, Adrian; Huggenberger, Peter; Schirmer, Mario
2017-04-01
Proper allocation and management of groundwater is an important and critical challenge under rising water demands of various environmental sectors but good groundwater quality is often limited because of urbanization and contamination of aquifers. Given the predictive capability of groundwater models, they are often the only viable means of providing input to water management decisions. However, modelling flow and transport processes can be difficult due to their unknown subsurface heterogeneity and typically unknown distribution of contaminants. As a result water resource management tasks are based on uncertain assumption on contaminants patterns and this uncertainty is typically not incorporated into the assessment of risks associated with different proposed management scenarios. A three-dimensional groundwater model was used to improve water resource management for a study area, where drinking water production is close to different former landfills and industrial areas. To avoid drinking water contamination, artificial groundwater recharge with surface water into the gravel aquifer is used to create a hydraulic barrier between contaminated sites and drinking water extraction wells. The model was used for simulating existing and proposed water management strategies as a tool to ensure the utmost security for drinking water. A systematic evaluation of the flow direction and magnitude between existing observation points using a newly developed three point estimation method for a large amount of scenarios was carried out. Due to the numerous observation points 32 triangles (three-points) were created which cover the entire area around the Hardwald. We demonstrated that systematically applying our developed methodology helps to identify important locations which are sensitive to changing boundary conditions and where additional protection is required without highly computational demanding transport modelling. The presented integrated approach using the flow direction
Three-dimensional modeling of diesel engine intake flow, combustion and emissions-II
Energy Technology Data Exchange (ETDEWEB)
Reitz, R.D.; Rutland, C.J.
1993-09-01
A three-dimensional computer code, KIVA, is being modified to include state-of-the-art submodels for diesel engine flow and combustion. Improved and/or new submodels which have already been implemented and previously reported are: Wall heat transfer with unsteadiness and compressibility, laminar-turbulent characteristic time combustion with unburned HC and Zeldo`vich NO{sub x}, and spray/wall impingement with rebounding and sliding drops. Progress on the implementation of improved spray drop drag and drop breakup models, the formulation and testing of a multistep kinetics ignition model and preliminary soot modeling results are described in this report. In addition, the use of a block structured version of KIVA to model the intake flow process is described. A grid generation scheme has been developed for modeling realistic (complex) engine geometries, and computations have been made of intake flow in the ports and combustion chamber of a two-intake-valve engine. The research also involves the use of the code to assess the effects of subprocesses on diesel engine performance. The accuracy of the predictions is being tested by comparisons with engine experiments. To date, comparisons have been made with measured engine cylinder pressure, temperature and heat flux data, and the model results are in good agreement with the experiments. Work is in progress that will allow validation of in-cylinder flow and soot formation predictions. An engine test facility is described that is being used to provide the needed validation data. Test results have been obtained showing the effect of injection rate and split injections on engine performance and emissions.
Modeling Vehicle Collision Angle in Traffic Crashes Based on Three-Dimensional Laser Scanning Data
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Nengchao Lyu
2017-02-01
Full Text Available In road traffic accidents, the analysis of a vehicle’s collision angle plays a key role in identifying a traffic accident’s form and cause. However, because accurate estimation of vehicle collision angle involves many factors, it is difficult to accurately determine it in cases in which less physical evidence is available and there is a lack of monitoring. This paper establishes the mathematical relation model between collision angle, deformation, and normal vector in the collision region according to the equations of particle deformation and force in Hooke’s law of classical mechanics. At the same time, the surface reconstruction method suitable for a normal vector solution is studied. Finally, the estimation model of vehicle collision angle is presented. In order to verify the correctness of the model, verification of multi-angle collision experiments and sensitivity analysis of laser scanning precision for the angle have been carried out using three-dimensional (3D data obtained by a 3D laser scanner in the collision deformation zone. Under the conditions with which the model has been defined, validation results show that the collision angle is a result of the weighted synthesis of the normal vector of the collision point and the weight value is the deformation of the collision point corresponding to normal vectors. These conclusions prove the applicability of the model. The collision angle model proposed in this paper can be used as the theoretical basis for traffic accident identification and cause analysis. It can also be used as a theoretical reference for the study of the impact deformation of elastic materials.
Directory of Open Access Journals (Sweden)
Jingjing Tang
2018-04-01
Full Text Available In the past, two-dimensional radiation transfer models (2-D models were widely used to investigate the optical performance of linear compound parabolic concentrators (CPCs, in which the radiation transfer on the cross-section of CPC troughs is considered. However, the photovoltaic efficiency of solar cells depends on the real incidence angle instead of the projection incidence angle, thus 2-D models can’t reasonably evaluate the photovoltaic performance of CPC-based photovoltaic systems (CPVs. In this work, three-dimensional radiation transfer (3-D model within CPC-θa/θe, the CPC with a maximum exit angle θe for radiation within its acceptance angle (θa, is investigated by means of vector algebra, solar geometry and imaging principle of plane mirror, and effects of geometry of CPV-θa/θe on its annual electricity generation are studied. Analysis shows that, as compared to similar photovoltaic (PV panels, the use of CPCs makes the incident angle of solar rays on solar cells increase thus lowers the photovoltaic conversion efficiency of solar cells. Calculations show that, 2-D models can reasonably predict the optical performance of CPVs, but such models always overestimate the photovoltaic performance of CPVs, and even can’t predict the variation trend of annual power output of CPV-θa/θe with θe. Results show that, for full CPV-θa/θe with a given θa, the annual power output increases with θe first and then comes to a halt as θe > 83°, whereas for truncated CPV-θa/θe with a given geometric concentration (Ct, the annual power output decreases with θe.
International Nuclear Information System (INIS)
Lee, Yoonhee; Cho, Nam Zin
2014-01-01
Highlights: • Two-temperature homogenized model is applied to thermal analysis of fully ceramic microencapsulated (FCM) fuel. • Based on the results of Monte Carlo calculation, homogenized parameters are obtained. • 2-D FEM/1-D FDM hybrid method for the model is used to obtain 3-D temperature profiles. • The model provides the fuel-kernel and SiC matrix temperatures separately. • Compared to UO 2 fuel, the FCM fuel shows ∼560 K lower maximum temperatures at steady- and transient states. - Abstract: The fully ceramic microencapsulated (FCM) fuel, one of the accident tolerant fuel (ATF) concepts, consists of TRISO particles randomly dispersed in SiC matrix. This high heterogeneity in compositions leads to difficulty in explicit thermal calculation of such a fuel. For thermal analysis of a fuel element of very high temperature reactors (VHTRs) which has a similar configuration to FCM fuel, two-temperature homogenized model was recently proposed by the authors. The model was developed using particle transport Monte Carlo method for heat conduction problems. It gives more realistic temperature profiles, and provides the fuel-kernel and graphite temperatures separately. In this paper, we apply the two-temperature homogenized model to three-dimensional single-channel thermal analysis of the FCM fuel element for steady- and transient-states using 2-D FEM/1-D FDM hybrid method. In the analyses, we assume that the power distribution is uniform in radial direction at steady-state and that in axial direction it is in the form of cosine function for simplicity. As transient scenarios, we consider (i) coolant inlet temperature transient, (ii) inlet mass flow rate transient, and (iii) power transient. The results of analyses are compared to those of conventional UO 2 fuel having the same geometric dimension and operating conditions
Three-dimensional model of corotating streams in the solar wind 3. Magnetohydrodynamic streams
International Nuclear Information System (INIS)
Pizzo, V.J.
1982-01-01
The focus of this paper is two-fold: (1) to examine how the presence of the spiral magnetic field affects the evolution of interplanetary corotating solar wind streams, and (2) to ascertain the nature of secondary large-scale phenomena likely to be associated with streams having a pronounced three-dimensional (3-D) structure. The dynamics are presumed to be governed by the nonlinear polytropic, single-fluid, 3-D MHD equations. Solutions are obtained with an explicit, Eulerian, finite differences technique that makes use of a simple form of artificial diffusion for handling shocks. For smooth axisymmetric flows, the picture of magnetically induced meridional motions previously established by linear models requires only minor correction. In the case of broad 3-D streams input near the sun, inclusion of the magnetic field is found to retard the kinematic steepening at the stream front substantially but to produce little deviation from planar flow. For the more realistic case of initially sharply bounded streams, however, it becomes essential to account for magnetic effects in the formulation. Whether a full 3-D treatment is required depends upon the latitudinal geometry of the stream
Li, Jianfeng; Xiao, Mingqing; Liang, Yajun; Tang, Xilang; Li, Chao
2018-01-01
The solenoid valve is a kind of basic automation component applied widely. It’s significant to analyze and predict its degradation failure mechanism to improve the reliability of solenoid valve and do research on prolonging life. In this paper, a three-dimensional finite element analysis model of solenoid valve is established based on ANSYS Workbench software. A sequential coupling method used to calculate temperature filed and mechanical stress field of solenoid valve is put forward. The simulation result shows the sequential coupling method can calculate and analyze temperature and stress distribution of solenoid valve accurately, which has been verified through the accelerated life test. Kalman filtering algorithm is introduced to the data processing, which can effectively reduce measuring deviation and restore more accurate data information. Based on different driving current, a kind of failure mechanism which can easily cause the degradation of coils is obtained and an optimization design scheme of electro-insulating rubbers is also proposed. The high temperature generated by driving current and the thermal stress resulting from thermal expansion can easily cause the degradation of coil wires, which will decline the electrical resistance of coils and result in the eventual failure of solenoid valve. The method of finite element analysis can be applied to fault diagnosis and prognostic of various solenoid valves and improve the reliability of solenoid valve’s health management.
Three dimensional modeling of pulverized coal combustion in a 600 MW corner fired boiler
Dal-Secco, Sandro
2000-12-01
The three-dimensional code ESTET developed at the LNH has been used to predict the reactive flow in a 600 MW coal fired boiler. Assuming a no-slip condition between the gas and the coal, the equations for a gas-particle mixture can be written. The pulverized coal particle size distribution is represented by a discrete number of particle size groups determined by the measured fineness distribution. The combustion models taking into account the pyrolysis of the particle and the heterogeneous combustion of char have been validated using intensive measurements performed on the 600 MW utility boiler. Heat fluxes were measured along the walls of the furnace and satisfactory agreement between computation and measurements has been achieved in terms of maximum flux location and heat flux intensity. Local measurements of velocities using LDV probe, gas temperature and gas species concentrations were performed in the vicinity of one burner and compared with the computed variables. Again we have observed a good agreement between the computations and the measurements in terms of jet penetration, temperature distribution, oxygen concentration and ash content.
Zhuang, Zhenfeng; Thibault, Simon
2017-11-01
One of the key issues in conventional wide-angle lenses is the well-known cosine-fourth power law problem causing the illumination falloff at its image space. This paper explores methods of improving illumination in the image space in panomorph lenses. By tracing skew rays within the defined field of view and pupil diameter, we obtained the actual position of the three-dimensional pupil model of the entrance pupil (EP) and exit pupil (XP). Based on the law of irradiance transport conservation, the relation between the area of the EP projection and illumination in the image space is derived to investigate the factors affecting the illumination on the peripheral field. A panomorph lens has been optimized as an example by providing a self-defined operation in the optimization process. The characteristic of the EP and XP in panomorph lenses is qualitatively analyzed. Compared with the conventional design method, the proposed design strategy can enhance the illumination with and without polarized light based on qualitatively evaluating the area of projected EP. It is demonstrated that this method enables the enhancement of the illumination without additional film coating.
Three-dimensional wave-induced current model equations and radiation stresses
Xia, Hua-yong
2017-08-01
After the approach by Mellor (2003, 2008), the present paper reports on a repeated effort to derive the equations for three-dimensional wave-induced current. Via the vertical momentum equation and a proper coordinate transformation, the phase-averaged wave dynamic pressure is well treated, and a continuous and depth-dependent radiation stress tensor, rather than the controversial delta Dirac function at the surface shown in Mellor (2008), is provided. Besides, a phase-averaged vertical momentum flux over a sloping bottom is introduced. All the inconsistencies in Mellor (2003, 2008), pointed out by Ardhuin et al. (2008) and Bennis and Ardhuin (2011), are overcome in the presently revised equations. In a test case with a sloping sea bed, as shown in Ardhuin et al. (2008), the wave-driving forces derived in the present equations are in good balance, and no spurious vertical circulation occurs outside the surf zone, indicating that Airy's wave theory and the approach of Mellor (2003, 2008) are applicable for the derivation of the wave-induced current model.
Application of three dimensional finite element modeling for the simulation of machining processes
International Nuclear Information System (INIS)
Fischer, C.E.; Wu, W.T.; Chigurupati, P.; Jinn, J.T.
2004-01-01
For many years, metal cutting simulations have been performed using two dimensional approximations of the actual process. Factors such as chip morphology, cutting force, temperature, and tool wear can all be predicted on the computer. However, two dimensional simulation is limited to processes which are orthogonal, or which can be closely approximated as orthogonal.Advances in finite element technology, coupled with continuing improvement in the availability of low cost, high performance computer hardware, have made the three dimensional simulation of a large variety of metal cutting processes practical. Specific improvements include efficient FEM solvers, and robust adaptive remeshing. As researchers continue to gain an improved understanding of wear, material representation, tool coatings, fracture, and other such phenomena, the machining simulation system also must adapt to incorporate these evolving models.To demonstrate the capabilities of the 3D simulation system, a variety of drilling, milling, and turning processes have been simulated and will be presented in this paper. Issues related to computation time and simulation accuracy will also be addressed
Three-Dimensional (3D Printing of Polymer-Metal Hybrid Materials by Fused Deposition Modeling
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Susanna Fafenrot
2017-10-01
Full Text Available Fused deposition modeling (FDM is a three-dimensional (3D printing technology that is usually performed with polymers that are molten in a printer nozzle and placed line by line on the printing bed or the previous layer, respectively. Nowadays, hybrid materials combining polymers with functional materials are also commercially available. Especially combinations of polymers with metal particles result in printed objects with interesting optical and mechanical properties. The mechanical properties of objects printed with two of these metal-polymer blends were compared to common poly (lactide acid (PLA printed objects. Tensile tests and bending tests show that hybrid materials mostly containing bronze have significantly reduced mechanical properties. Tensile strengths of the 3D-printed objects were unexpectedly nearly identical with those of the original filaments, indicating sufficient quality of the printing process. Our investigations show that while FDM printing allows for producing objects with mechanical properties similar to the original materials, metal-polymer blends cannot be used for the rapid manufacturing of objects necessitating mechanical strength.
Three-Dimensional (3D) Printing of Polymer-Metal Hybrid Materials by Fused Deposition Modeling.
Fafenrot, Susanna; Grimmelsmann, Nils; Wortmann, Martin; Ehrmann, Andrea
2017-10-19
Fused deposition modeling (FDM) is a three-dimensional (3D) printing technology that is usually performed with polymers that are molten in a printer nozzle and placed line by line on the printing bed or the previous layer, respectively. Nowadays, hybrid materials combining polymers with functional materials are also commercially available. Especially combinations of polymers with metal particles result in printed objects with interesting optical and mechanical properties. The mechanical properties of objects printed with two of these metal-polymer blends were compared to common poly (lactide acid) (PLA) printed objects. Tensile tests and bending tests show that hybrid materials mostly containing bronze have significantly reduced mechanical properties. Tensile strengths of the 3D-printed objects were unexpectedly nearly identical with those of the original filaments, indicating sufficient quality of the printing process. Our investigations show that while FDM printing allows for producing objects with mechanical properties similar to the original materials, metal-polymer blends cannot be used for the rapid manufacturing of objects necessitating mechanical strength.
Directory of Open Access Journals (Sweden)
Farooq Kiani
2007-07-01
Full Text Available Loss of function of dimeric glucose-6-phosphate dehydrogenase (G6PD represents the most common inborn error of metabolism throughout the world affecting an estimated 400 million people. In Germany, this enzymopathy is very rare.On the basis of G6PD crystal structures, we have analyzed six G6PD variants of German ancestry by three-dimensional modeling. All mutations present in the German population are either close to one of the three G6P or NADP(+ units or to the interface of the two monomers. Two of the three mutated amino acids of G6PD Vancouver are closer to the binding site of NADP(+. The G6PD Aachen mutation is also closer to the second NADP(+ unit. The G6PD Wayne mutation is closer to the G6P binding region. These mutations may affect the binding of G6P and NADP(+ units. Three mutations, i.e. G6PD Munich, G6PD Riverside and G6PD Gastonia, lie closer to the interface of the two monomers. These may also affect the interface of two monomers.None of these G6PD variants share mutations with the common G6PD variants known from the Mediterranean, Near East, or Africa indicating that they have developed independently. The G6PD variants have been compared with mutants from other populations and the implications for survival of G6PD variants from natural selection have been discussed.
Quantitative three-dimensional modeling of zeotile through discrete electron tomography.
Bals, Sara; Batenburg, K Joost; Liang, Duoduo; Lebedev, Oleg; Van Tendeloo, Gustaaf; Aerts, Alexander; Martens, Johan A; Kirschhock, Christine E A
2009-04-08
Discrete electron tomography is a new approach for three-dimensional reconstruction of nanoscale objects. The technique exploits prior knowledge of the object to be reconstructed, which results in an improvement of the quality of the reconstructions. Through the combination of conventional transmission electron microscopy and discrete electron tomography with a model-based approach, quantitative structure determination becomes possible. In the present work, this approach is used to unravel the building scheme of Zeotile-4, a silica material with two levels of structural order. The layer sequence of slab-shaped building units could be identified. Successive layers were found to be related by a rotation of 120 degrees, resulting in a hexagonal space group. The Zeotile-4 material is a demonstration of the concept of successive structuring of silica at two levels. At the first level, the colloid chemical properties of Silicalite-1 precursors are exploited to create building units with a slablike geometry. At the second level, the slablike units are tiled using a triblock copolymer to serve as a mesoscale structuring agent.
Directory of Open Access Journals (Sweden)
S. N. S. Jamaludin
2014-01-01
Full Text Available The composition of hydroxyapatite (HA as the ceramic phase and titanium (Ti as the metallic phase in HA/Ti functionally graded materials (FGMs shows an excellent combination of high biocompatibility and high mechanical properties in a structure. Because the gradation of these properties is one of the factors that affects the response of the functionally graded (FG plates, this paper is presented to show the domination of the grading parameter on the displacement and stress distribution of the plates. A three-dimensional (3D thermomechanical model of a 20-node brick quadratic element is used in the simulation of the thermoelastic behaviors of HA/Ti FG plates subjected to constant and functional thermal, mechanical, and thermomechanical loadings. The convergence properties of the present results are examined thoroughly in order to assess the accuracy of the theory applied and to compare them with the established research results. Instead of the grading parameter, this study reveals that the loading field distribution can be another factor that reflects the thermoelastic properties of the HA/Ti FG plates. The FG structure is found to be able to withstand the thermal stresses while preserving the high toughness properties and thus shows its ability to operate at high temperature.
Automated recovery of three-dimensional models of plant shoots from multiple color images.
Pound, Michael P; French, Andrew P; Murchie, Erik H; Pridmore, Tony P
2014-12-01
Increased adoption of the systems approach to biological research has focused attention on the use of quantitative models of biological objects. This includes a need for realistic three-dimensional (3D) representations of plant shoots for quantification and modeling. Previous limitations in single-view or multiple-view stereo algorithms have led to a reliance on volumetric methods or expensive hardware to record plant structure. We present a fully automatic approach to image-based 3D plant reconstruction that can be achieved using a single low-cost camera. The reconstructed plants are represented as a series of small planar sections that together model the more complex architecture of the leaf surfaces. The boundary of each leaf patch is refined using the level-set method, optimizing the model based on image information, curvature constraints, and the position of neighboring surfaces. The reconstruction process makes few assumptions about the nature of the plant material being reconstructed and, as such, is applicable to a wide variety of plant species and topologies and can be extended to canopy-scale imaging. We demonstrate the effectiveness of our approach on data sets of wheat (Triticum aestivum) and rice (Oryza sativa) plants as well as a unique virtual data set that allows us to compute quantitative measures of reconstruction accuracy. The output is a 3D mesh structure that is suitable for modeling applications in a format that can be imported in the majority of 3D graphics and software packages. © 2014 American Society of Plant Biologists. All Rights Reserved.
Three-dimensional Kinetic Pulsar Magnetosphere Models: Connecting to Gamma-Ray Observations
Kalapotharakos, Constantinos; Brambilla, Gabriele; Timokhin, Andrey; Harding, Alice K.; Kazanas, Demosthenes
2018-04-01
We present three-dimensional (3D) global kinetic pulsar magnetosphere models, where the charged particle trajectories and the corresponding electromagnetic fields are treated self-consistently. For our study, we have developed a Cartesian 3D relativistic particle-in-cell code that incorporates radiation reaction forces. We describe our code and discuss the related technical issues, treatments, and assumptions. Injecting particles up to large distances in the magnetosphere, we apply arbitrarily low to high particle injection rates, and obtain an entire spectrum of solutions from close to the vacuum-retarded dipole to close to the force-free (FF) solution, respectively. For high particle injection rates (close to FF solutions), significant accelerating electric field components are confined only near the equatorial current sheet outside the light cylinder. A judicious interpretation of our models allows the particle emission to be calculated, and consequently, the corresponding realistic high-energy sky maps and spectra to be derived. Using model parameters that cover the entire range of spin-down powers of Fermi young and millisecond pulsars, we compare the corresponding model γ-ray light curves, cutoff energies, and total γ-ray luminosities with those observed by Fermi to discover a dependence of the particle injection rate, { \\mathcal F }, on the spin-down power, \\dot{{ \\mathcal E }}, indicating an increase of { \\mathcal F } with \\dot{{ \\mathcal E }}. Our models, guided by Fermi observations, provide field structures and particle distributions that are not only consistent with each other but also able to reproduce a broad range of the observed γ-ray phenomenologies of both young and millisecond pulsars.
Wilkinson, Dan C; Alva-Ornelas, Jackelyn A; Sucre, Jennifer M S; Vijayaraj, Preethi; Durra, Abdo; Richardson, Wade; Jonas, Steven J; Paul, Manash K; Karumbayaram, Saravanan; Dunn, Bruce; Gomperts, Brigitte N
2017-02-01
Stem cell technologies, especially patient-specific, induced stem cell pluripotency and directed differentiation, hold great promise for changing the landscape of medical therapies. Proper exploitation of these methods may lead to personalized organ transplants, but to regenerate organs, it is necessary to develop methods for assembling differentiated cells into functional, organ-level tissues. The generation of three-dimensional human tissue models also holds potential for medical advances in disease modeling, as full organ functionality may not be necessary to recapitulate disease pathophysiology. This is specifically true of lung diseases where animal models often do not recapitulate human disease. Here, we present a method for the generation of self-assembled human lung tissue and its potential for disease modeling and drug discovery for lung diseases characterized by progressive and irreversible scarring such as idiopathic pulmonary fibrosis (IPF). Tissue formation occurs because of the overlapping processes of cellular adhesion to multiple alveolar sac templates, bioreactor rotation, and cellular contraction. Addition of transforming growth factor-β1 to single cell-type mesenchymal organoids resulted in morphologic scarring typical of that seen in IPF but not in two-dimensional IPF fibroblast cultures. Furthermore, this lung organoid may be modified to contain multiple lung cell types assembled into the correct anatomical location, thereby allowing cell-cell contact and recapitulating the lung microenvironment. Our bottom-up approach for synthesizing patient-specific lung tissue in a scalable system allows for the development of relevant human lung disease models with the potential for high throughput drug screening to identify targeted therapies. Stem Cells Translational Medicine 2017;6:622-633. © 2016 The Authors Stem Cells Translational Medicine published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.
Emde, Claudia; Barlakas, Vasileios; Cornet, Céline; Evans, Frank; Wang, Zhen; Labonotte, Laurent C.; Macke, Andreas; Mayer, Bernhard; Wendisch, Manfred
2018-04-01
Initially unpolarized solar radiation becomes polarized by scattering in the Earth's atmosphere. In particular molecular scattering (Rayleigh scattering) polarizes electromagnetic radiation, but also scattering of radiation at aerosols, cloud droplets (Mie scattering) and ice crystals polarizes. Each atmospheric constituent produces a characteristic polarization signal, thus spectro-polarimetric measurements are frequently employed for remote sensing of aerosol and cloud properties. Retrieval algorithms require efficient radiative transfer models. Usually, these apply the plane-parallel approximation (PPA), assuming that the atmosphere consists of horizontally homogeneous layers. This allows to solve the vector radiative transfer equation (VRTE) efficiently. For remote sensing applications, the radiance is considered constant over the instantaneous field-of-view of the instrument and each sensor element is treated independently in plane-parallel approximation, neglecting horizontal radiation transport between adjacent pixels (Independent Pixel Approximation, IPA). In order to estimate the errors due to the IPA approximation, three-dimensional (3D) vector radiative transfer models are required. So far, only a few such models exist. Therefore, the International Polarized Radiative Transfer (IPRT) working group of the International Radiation Commission (IRC) has initiated a model intercomparison project in order to provide benchmark results for polarized radiative transfer. The group has already performed an intercomparison for one-dimensional (1D) multi-layer test cases [phase A, 1]. This paper presents the continuation of the intercomparison project (phase B) for 2D and 3D test cases: a step cloud, a cubic cloud, and a more realistic scenario including a 3D cloud field generated by a Large Eddy Simulation (LES) model and typical background aerosols. The commonly established benchmark results for 3D polarized radiative transfer are available at the IPRT website (http
SU-E-T-754: Three-Dimensional Patient Modeling Using Photogrammetry for Collision Avoidance
Energy Technology Data Exchange (ETDEWEB)
Popple, R; Cardan, R [Univ Alabama Birmingham, Birmingham, AL (United States)
2015-06-15
Purpose: To evaluate photogrammetry for creating a three-dimensional patient model. Methods: A mannequin was configured on the couch of a CT scanner to simulate a patient setup using an indexed positioning device. A CT fiducial was placed on the indexed CT table-overlay at the reference index position. Two dimensional photogrammetry targets were placed on the table in known positions. A digital SLR camera was used to obtain 27 images from different positions around the CT table. The images were imported into a commercial photogrammetry package and a 3D model constructed. Each photogrammetry target was identified on 2 to 5 images. The CT DICOM metadata and the position of the CT fiducial were used to calculate the coordinates of the photogrammetry targets in the CT image frame of reference. The coordinates were transferred to the photogrammetry software to orient the 3D model. The mannequin setup was transferred to the treatment couch of a linear accelerator and positioned at isocenter using in-room lasers. The treatment couch coordinates were noted and compared with prediction. The collision free regions were measured over the full range of gantry and table motion and were compared with predictions obtained using a general purpose polygon interference algorithm. Results: The reconstructed 3D model consisted of 180000 triangles. The difference between the predicted and measured couch positions were 5 mm, 1 mm, and 1 mm for longitudinal, lateral, and vertical, respectively. The collision prediction tested 64620 gantry table combinations in 11.1 seconds. The accuracy was 96.5%, with false positive and negative results occurring at the boundaries of the collision space. Conclusion: Photogrammetry can be used as a tool for collision avoidance during treatment planning. The results indicate that a buffer zone is necessary to avoid false negatives at the boundary of the collision-free zone. Testing with human patients is underway. Research partially supported by a grant
International Nuclear Information System (INIS)
Wei Xin; Zhong Liming; Xie Xiaodong; Wang Chaohua; You Jian; Hu Hong; Hu Kongqiong; Zhao Xiaowei
2012-01-01
Objective: To explore virtual three-dimensional (3D) model for intravascular interventional devices,the method of preoperative simulation and its value in clinical work. Methods: The virtual models including catheter, guide wire, stent and coil were established by using the 3D moulding software of 3D Studio MAX R3. The interventional preoperative simulation was performed on personal computer including 21 patients of cerebral aneurysm embolization (anterior communicating artery 5, posterior communicating artery 10,middle cerebral artery 3, internal carotid artery 2, and vertebral artery 1), during interventional procedures, the surgeon relied on the simulation results for plastic micro-guide wire, catheter and the release of micro-coils and stents. Results: (1) All the virtual instruments and real instruments had similar shape,the overall tine for constructing virtual model was about 20 hours. The preoperative simulation took 50 to 80 minutes. (2) The simulation result of catheter insertion in the 18 cases had relevant value to guide micro-catheter, molding micro-guide wire tip, and shortened the operating time. For embolization, the simulation results of filling coil and releasing stent were similar to surgical results in 76% of the patients (16/21). (3)For teaching and training, 93% (38/41) of doctors in training believed that preoperative simulation facilitated the understanding of surgery. Conclusions: The method of virtual model of intravascular interventional devices was reliable. The preoperative simulation results could be used to guide practical clinical operation with relatively high degree of similarity, and could play a role in promoting researches on interventional virtual operations. (authors)
International Nuclear Information System (INIS)
Billaux, D.; Long, J.C.S.; Peterson, J.E. Jr.
1990-03-01
A model for channelized flow in three-dimensional, random networks of fractures has been developed. In this model, the fractures are disc-shaped discontinuities in an impermeable matrix. Within each fracture, flow occurs only in a network of random channels. The channels in each fracture can be generated independently with random distributions of length, conductivity, and orientation in the fracture plane. Boundary conditions are specified on the sides of a ''flow region,'' and at the intersections of the channels with interior ''holes'' specified by the user to simulate boreholes or drifts. This code is part of a set of programs used to generate two-dimensional or three-dimensional random fracture networks, plot them, compute flow through them and analyze the results. 8 refs., 13 figs
Energy Technology Data Exchange (ETDEWEB)
Boyd, J [Cardiovascular Research Group Physics, University of New England, Armidale, NSW 2351 (Australia); Buick, J M [Department of Mechanical and Design Engineering, University of Portsmouth, Anglesea Building, Anglesea Road, Portsmouth PO1 3DJ (United Kingdom)
2008-10-21
Numerical modelling is a powerful tool in the investigation of human blood flow and arterial diseases such as atherosclerosis. It is known that near wall velocity and shear are important in the pathogenesis and progression of atherosclerosis. In this paper results for a simulation of blood flow in a three-dimensional carotid artery geometry using the lattice Boltzmann method are presented. The velocity fields in the body of the fluid are analysed at six times of interest during a physiologically accurate velocity waveform. It is found that the three-dimensional model agrees well with previous literature results for carotid artery flow. Regions of low near wall velocity and circulatory flow are observed near the outer wall of the bifurcation and in the lower regions of the external carotid artery, which are regions that are typically prone to atherosclerosis.
International Nuclear Information System (INIS)
Boyd, J; Buick, J M
2008-01-01
Numerical modelling is a powerful tool in the investigation of human blood flow and arterial diseases such as atherosclerosis. It is known that near wall velocity and shear are important in the pathogenesis and progression of atherosclerosis. In this paper results for a simulation of blood flow in a three-dimensional carotid artery geometry using the lattice Boltzmann method are presented. The velocity fields in the body of the fluid are analysed at six times of interest during a physiologically accurate velocity waveform. It is found that the three-dimensional model agrees well with previous literature results for carotid artery flow. Regions of low near wall velocity and circulatory flow are observed near the outer wall of the bifurcation and in the lower regions of the external carotid artery, which are regions that are typically prone to atherosclerosis.
Directory of Open Access Journals (Sweden)
Hainian Wang
2014-02-01
Full Text Available X-ray CT (computed tomography was used to scan asphalt mixture specimen to obtain high resolution continuous cross-section images and the meso-structure. According to the theory of three-dimensional (3D reconstruction, the 3D reconstruction algorithm was investigated in this paper. The key to the reconstruction technique is the acquisition of the voxel positions and the relationship between the pixel element and node. Three-dimensional numerical model of asphalt mixture specimen was created by a self-developed program. A splitting test was conducted to predict the stress distributions of the asphalt mixture and verify the rationality of the 3D model.
Berdejo, Javier; Shiota, Maiko; Mihara, Hirotsugu; Itabashi, Yuji; Utsunomiya, Hiroto; Shiota, Takahiro
2017-05-01
Evaluation of eccentric mitral regurgitation (MR) remains extremely difficult and the role played by its etiology, functional or degenerative, is not well understood. This study aimed to demonstrate the value of three-dimensional transesophageal echocardiography (3DTEE) in the evaluation of eccentric MR identifying geometric differences in the vena contracta area between functional and degenerative etiologies. We studied 61 patients with eccentric MR (30 functional and 31 degenerative). Regurgitant orifice area was determined by the two-dimensional proximal isovelocity surface area (2DPISA) and the 3DTEE methods. The ratio between maximum and minimum lengths of the vena contracta was calculated in each patient. Effective regurgitant orifice area by the 2DPISA method was smaller than that estimated by 3DTEE (0.56±0.21 vs 0.72±0.25 cm 2 ). A better correlation between both methods was seen in degenerative mitral regurgitation (DMR; r=.83), with a mean underestimation of 8.2% by the 2DPISA method. A much worse correlation was found in functional mitral regurgitation (FMR; r=.39), where a mean underestimation by the 2DPISA method of 29.1% was observed. There was a more elongated and curved vena contracta in FMR compared to that in DMR (length ratio: 3.4±1.0 vs 2.2±0.7, Pechocardiography identifies a more elongated regurgitant orifice in eccentric FMR compared to that in eccentric DMR. This difference may explain the greater underestimation of effective regurgitant orifice area by the 2DPISA method in FMR. High-quality 3DTEE analysis of vena contracta area would be a highly recommended alternative. © 2017, Wiley Periodicals, Inc.
Directory of Open Access Journals (Sweden)
Jie Ni
2016-02-01
Full Text Available Prostate cancer (CaP is the most commonly diagnosed and the second leading cause of death from cancer in males in USA. Prostate orthotopic mouse model has been widely used to study human CaP in preclinical settings. Measurement of changes in tumor size obtained from noninvasive diagnostic images is a standard method for monitoring responses to anticancer modalities. This article reports for the first time the usage of a three-dimensional (3D ultrasound system equipped with photoacoustic (PA imaging in monitoring longitudinal prostate tumor growth in a PC-3 orthotopic NODSCID mouse model (n = 8. Two-dimensional and 3D modes of ultrasound show great ability in accurately depicting the size and shape of prostate tumors. PA function on two-dimensional and 3D images showed average oxygen saturation and average hemoglobin concentration of the tumor. Results showed a good fit in representative exponential tumor growth curves (n = 3; r2 = 0.948, 0.955, and 0.953, respectively and a good correlation of tumor volume measurements performed in vivo with autopsy (n = 8, r = 0.95, P < .001. The application of 3D ultrasound imaging proved to be a useful imaging modality in monitoring tumor growth in an orthotopic mouse model, with advantages such as high contrast, uncomplicated protocols, economical equipment, and nonharmfulness to animals. PA mode also enabled display of blood oxygenation surrounding the tumor and tumor vasculature and angiogenesis, making 3D ultrasound imaging an ideal tool for preclinical cancer research.
Visualizing Three-dimensional Slab Geometries with ShowEarthModel
Chang, B.; Jadamec, M. A.; Fischer, K. M.; Kreylos, O.; Yikilmaz, M. B.
2017-12-01
Seismic data that characterize the morphology of modern subducted slabs on Earth suggest that a two-dimensional paradigm is no longer adequate to describe the subduction process. Here we demonstrate the effect of data exploration of three-dimensional (3D) global slab geometries with the open source program ShowEarthModel. ShowEarthModel was designed specifically to support data exploration, by focusing on interactivity and real-time response using the Vrui toolkit. Sixteen movies are presented that explore the 3D complexity of modern subduction zones on Earth. The first movie provides a guided tour through the Earth's major subduction zones, comparing the global slab geometry data sets of Gudmundsson and Sambridge (1998), Syracuse and Abers (2006), and Hayes et al. (2012). Fifteen regional movies explore the individual subduction zones and regions intersecting slabs, using the Hayes et al. (2012) slab geometry models where available and the Engdahl and Villasenor (2002) global earthquake data set. Viewing the subduction zones in this way provides an improved conceptualization of the 3D morphology within a given subduction zone as well as the 3D spatial relations between the intersecting slabs. This approach provides a powerful tool for rendering earth properties and broadening capabilities in both Earth Science research and education by allowing for whole earth visualization. The 3D characterization of global slab geometries is placed in the context of 3D slab-driven mantle flow and observations of shear wave splitting in subduction zones. These visualizations contribute to the paradigm shift from a 2D to 3D subduction framework by facilitating the conceptualization of the modern subduction system on Earth in 3D space.
Pinsky, Peter M
2014-05-15
Intrastromal inlays for refractive correction of presbyopia are being adopted into clinical practice. An important concern is the effect of the inlay on the long-term health of the cornea due to disturbances in the concentration profiles of metabolic species. A three-dimensional metabolic model for the cornea is employed to investigate oxygen, glucose, and lactate ion transport in the cornea and to estimate changes in species concentrations induced by the introduction of a hydrogel inlay. A reaction-diffusion metabolic model, appropriate for highly oxygen-permeable hydrogel inlays, is used to describe cellular consumption of oxygen and glucose and production of lactic acid. A three-layer corneal geometry (epithelium, stroma, endothelium) is employed with a hydrogel inlay placed under a lamellar flap. The model is solved numerically by the finite element method. For a commercially available hydrogel material with a relative inlay diffusivity of 43.5%, maximum glucose depletion and lactate ion accumulation occur anterior to the inlay and both are less than 3%. Below 20% relative diffusivity, glucose depletion and lactate ion accumulation increase exponentially. Glucose depletion increases slightly with increasing depth of inlay placement. The flux of metabolic species is modified by an inlay, depending on the inlay relative diffusivity. For commercially available hydrogel materials and a typical inlay design, predicted changes in species concentrations are small when compared to the variation of concentrations across the normal cornea. In general, glucose depletion and lactate ion accumulation are highly sensitive to inlay diffusivity and somewhat insensitive to inlay depth. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.
Nickerson, C. A.; Goodwin, T. J.; Terlonge, J.; Ott, C. M.; Buchanan, K. L.; Uicker, W. C.; Emami, K.; LeBlanc, C. L.; Ramamurthy, R.; Clarke, M. S.;
2001-01-01
The lack of readily available experimental systems has limited knowledge pertaining to the development of Salmonella-induced gastroenteritis and diarrheal disease in humans. We used a novel low-shear stress cell culture system developed at the National Aeronautics and Space Administration in conjunction with cultivation of three-dimensional (3-D) aggregates of human intestinal tissue to study the infectivity of Salmonella enterica serovar Typhimurium for human intestinal epithelium. Immunohistochemical characterization and microscopic analysis of 3-D aggregates of the human intestinal epithelial cell line Int-407 revealed that the 3-D cells more accurately modeled human in vivo differentiated tissues than did conventional monolayer cultures of the same cells. Results from infectivity studies showed that Salmonella established infection of the 3-D cells in a much different manner than that observed for monolayers. Following the same time course of infection with Salmonella, 3-D Int-407 cells displayed minimal loss of structural integrity compared to that of Int-407 monolayers. Furthermore, Salmonella exhibited significantly lower abilities to adhere to, invade, and induce apoptosis of 3-D Int-407 cells than it did for infected Int-407 monolayers. Analysis of cytokine expression profiles of 3-D Int-407 cells and monolayers following infection with Salmonella revealed significant differences in expression of interleukin 1alpha (IL-1alpha), IL-1beta, IL-6, IL-1Ra, and tumor necrosis factor alpha mRNAs between the two cultures. In addition, uninfected 3-D Int-407 cells constitutively expressed higher levels of transforming growth factor beta1 mRNA and prostaglandin E2 than did uninfected Int-407 monolayers. By more accurately modeling many aspects of human in vivo tissues, the 3-D intestinal cell model generated in this study offers a novel approach for studying microbial infectivity from the perspective of the host-pathogen interaction.
Three-dimensional in vitro tumor models for cancer research and drug evaluation.
Xu, Xian; Farach-Carson, Mary C; Jia, Xinqiao
2014-11-15
Cancer occurs when cells acquire genomic instability and inflammation, produce abnormal levels of epigenetic factors/proteins and tumor suppressors, reprogram the energy metabolism and evade immune destruction, leading to the disruption of cell cycle/normal growth. An early event in carcinogenesis is loss of polarity and detachment from the natural basement membrane, allowing cells to form distinct three-dimensional (3D) structures that interact with each other and with the surrounding microenvironment. Although valuable information has been accumulated from traditional in vitro studies in which cells are grown on flat and hard plastic surfaces (2D culture), this culture condition does not reflect the essential features of tumor tissues. Further, fundamental understanding of cancer metastasis cannot be obtained readily from 2D studies because they lack the complex and dynamic cell-cell communications and cell-matrix interactions that occur during cancer metastasis. These shortcomings, along with lack of spatial depth and cell connectivity, limit the applicability of 2D cultures to accurate testing of pharmacologically active compounds, free or sequestered in nanoparticles. To recapitulate features of native tumor microenvironments, various biomimetic 3D tumor models have been developed to incorporate cancer and stromal cells, relevant matrix components, and biochemical and biophysical cues, into one spatially and temporally integrated system. In this article, we review recent advances in creating 3D tumor models employing tissue engineering principles. We then evaluate the utilities of these novel models for the testing of anticancer drugs and their delivery systems. We highlight the profound differences in responses from 3D in vitro tumors and conventional monolayer cultures. Overall, strategic integration of biological principles and engineering approaches will both improve understanding of tumor progression and invasion and support discovery of more personalized
Three-dimensional hydrogel cell culture systems for modeling neural tissue
Frampton, John
Two-dimensional (2-D) neural cell culture systems have served as physiological models for understanding the cellular and molecular events that underlie responses to physical and chemical stimuli, control sensory and motor function, and lead to the development of neurological diseases. However, the development of three-dimensional (3-D) cell culture systems will be essential for the advancement of experimental research in a variety of fields including tissue engineering, chemical transport and delivery, cell growth, and cell-cell communication. In 3-D cell culture, cells are provided with an environment similar to tissue, in which they are surrounded on all sides by other cells, structural molecules and adhesion ligands. Cells grown in 3-D culture systems display morphologies and functions more similar to those observed in vivo, and can be cultured in such a way as to recapitulate the structural organization and biological properties of tissue. This thesis describes a hydrogel-based culture system, capable of supporting the growth and function of several neural cell types in 3-D. Alginate hydrogels were characterized in terms of their biomechanical and biochemical properties and were functionalized by covalent attachment of whole proteins and peptide epitopes. Methods were developed for rapid cross-linking of alginate hydrogels, thus permitting the incorporation of cells into 3-D scaffolds without adversely affecting cell viability or function. A variety of neural cell types were tested including astrocytes, microglia, and neurons. Cells remained viable and functional for longer than two weeks in culture and displayed process outgrowth in 3-D. Cell constructs were created that varied in cell density, type and organization, providing experimental flexibility for studying cell interactions and behavior. In one set of experiments, 3-D glial-endothelial cell co-cultures were used to model blood-brain barrier (BBB) structure and function. This co-culture system was
Maltha, J. Bacchetti, A.C. & Heijer, T.
1977-01-01
Two different computer programs have been developed for a two-dimensional and a three-dimensional crash victim model. In this study the three-dimensional model is tested in comparison with the two-dimensional model. A test run of the two-dimensional model is simulated with the SWOV-TNO
Damayanti, Ista; Lilies, Latief, Benny S.
2017-02-01
Three-dimensional (3-D) printing has been identified as an innovative manufacturing technology of functional parts. The 3-D model was produced based on CT-Scan using Osyrix software, where automatic segmentation was performed and convert into STL format. This STL format was then ready to be produced physically, layer-by-layer to create 3-D model.
DEFF Research Database (Denmark)
Eldrup, Mads Røge; Andersen, Thomas Lykke
The present report presents results from a three-dimensional model test study carried out at Aalborg University in January 2018 with the new western breakwater in Port of Hanstholm as proposed by the contractor Aarsleff and their consultant Cowi. The objectives of the model tests were to study th...
Three-Dimensional Numerical Modeling of Acoustic Trapping in Glass Capillaries
DEFF Research Database (Denmark)
Ley, Mikkel Wennemoes Hvitfeld; Bruus, Henrik
2017-01-01
Acoustic traps are used to capture and handle suspended microparticles and cells in microfluidic applications. A particular simple and much-used acoustic trap consists of a commercially available, millimeter-sized, liquid-filled straight glass capillary actuated by a piezoelectric transducer. Here...... of localized acoustic resonance modes in such a straight acoustic waveguide without any geometrical cavities in the axial direction of the capillary. The model further predicts that some of these modes are well suited for acoustic trapping, and it provides estimates for their frequencies and quality factors...
STRATAQ: A three-dimensional Chemical Transport Model of the stratosphere
Directory of Open Access Journals (Sweden)
B. Grassi
Full Text Available A three-dimensional (3-D Chemical Transport Model (CTM of the stratosphere has been developed and used for a test study of the evolution of chemical species in the arctic lower stratosphere during winter 1996/97. This particular winter has been chosen for testing the model’s capabilities for its remarkable dynamical situation (very cold and strong polar vortex along with the availability of sparse chlorine, HNO_{3} and O_{3} data, showing also very low O_{3} values in late March/April. Due to those unusual features, the winter 1996/97 can be considered an excellent example of the impact of both dynamics and heterogeneous reactions on the chemistry of the stratosphere. Model integration has been performed from January to March 1997 and the resulting long-lived and short-lived tracer fields compared with available measurements. The model includes a detailed gas phase chemical scheme and a parameterization of the heterogeneous reactions occurring on liquid aerosol and polar stratospheric cloud (PSC surfaces. The transport is calculated using a semi-lagrangian flux scheme, forced by meteorological analyses. In such form, the STRATAQ CTM model is suitable for short-term integrations to study transport and chemical evolution related to "real" meteorological situations. Model simulation during the chosen winter shows intense PSC formation, with noticeable local HNO_{3} capture by PSCs, and the activation of vortex air leading to chlorine production and subsequent O_{3} destruction. The resulting model fields show generally good agreement with satellite data (MLS and TOMS, although the available observations, due to their limited number and time/space sparse nature, are not enough to effectively constraint the model. In particular, the model seems to perform well in reproducing the rapid processing of air inside the polar vortex on PSC converting reservoir species in active chlorine. In addition, it
A model of Stokesian peristalsis and vesicle transport in a three-dimensional closed cavity.
Aranda, Vivian; Cortez, Ricardo; Fauci, Lisa
2015-06-25
The complexity of the mechanics involved in the mammalian reproductive process is evident. Neither an ovum nor an embryo is self-propelled, but move through the oviduct or uterus due to the peristaltic action of the tube walls, imposed pressure gradients, and perhaps ciliary motion. Here we use the method of regularized Stokeslets to model the transport of an ovum or an embryo within a peristaltic tube. We represent the ovum or the embryo as a spherical vesicle of finite volume - not a massless point particle. The outer membrane of the neutrally buoyant vesicle is discretized by nodes that are joined by a network of springs. The elastic moduli of these springs are chosen large enough so that a spherical shape is maintained. For simplicity, here we choose an axisymmetric tube where the geometry of the two-dimensional cross-section along the tube axis reflects that of the sagittal cross-section of the uterine cavity. Although the tube motion is axisymmetric, the presence of the vesicle within the tube requires a fully three-dimensional model. As was found in Yaniv et al. (2009, 2012) for a 2D closed channel, we find that the flow dynamics in a 3D peristaltic tube are strongly influenced by the closed end and the manner in which the peristaltic wave damps out towards the closure. In addition, we demonstrate that the trajectory of a vesicle of finite volume can greatly differ from the trajectory of a massless fluid particle initially placed at the vesicle׳s centroid. Copyright © 2015 Elsevier Ltd. All rights reserved.
High-immersion three-dimensional display of the numerical computer model
Xing, Shujun; Yu, Xunbo; Zhao, Tianqi; Cai, Yuanfa; Chen, Duo; Chen, Zhidong; Sang, Xinzhu
2013-08-01
High-immersion three-dimensional (3D) displays making them valuable tools for many applications, such as designing and constructing desired building houses, industrial architecture design, aeronautics, scientific research, entertainment, media advertisement, military areas and so on. However, most technologies provide 3D display in the front of screens which are in parallel with the walls, and the sense of immersion is decreased. To get the right multi-view stereo ground image, cameras' photosensitive surface should be parallax to the public focus plane and the cameras' optical axes should be offset to the center of public focus plane both atvertical direction and horizontal direction. It is very common to use virtual cameras, which is an ideal pinhole camera to display 3D model in computer system. We can use virtual cameras to simulate the shooting method of multi-view ground based stereo image. Here, two virtual shooting methods for ground based high-immersion 3D display are presented. The position of virtual camera is determined by the people's eye position in the real world. When the observer stand in the circumcircle of 3D ground display, offset perspective projection virtual cameras is used. If the observer stands out the circumcircle of 3D ground display, offset perspective projection virtual cameras and the orthogonal projection virtual cameras are adopted. In this paper, we mainly discussed the parameter setting of virtual cameras. The Near Clip Plane parameter setting is the main point in the first method, while the rotation angle of virtual cameras is the main point in the second method. In order to validate the results, we use the D3D and OpenGL to render scenes of different viewpoints and generate a stereoscopic image. A realistic visualization system for 3D models is constructed and demonstrated for viewing horizontally, which provides high-immersion 3D visualization. The displayed 3D scenes are compared with the real objects in the real world.
Three-dimensional simulations of pure deflagration models for thermonuclear supernovae
International Nuclear Information System (INIS)
Long, Min; Jordan, George C. IV; Van Rossum, Daniel R.; Diemer, Benedikt; Graziani, Carlo; Kessler, Richard; Rich, Paul; Lamb, Don Q.; Meyer, Bradley
2014-01-01
We present a systematic study of the pure deflagration model of Type Ia supernovae (SNe Ia) using three-dimensional, high-resolution, full-star hydrodynamical simulations, nucleosynthetic yields calculated using Lagrangian tracer particles, and light curves calculated using radiation transport. We evaluate the simulations by comparing their predicted light curves with many observed SNe Ia using the SALT2 data-driven model and find that the simulations may correspond to under-luminous SNe Iax. We explore the effects of the initial conditions on our results by varying the number of randomly selected ignition points from 63 to 3500, and the radius of the centered sphere they are confined in from 128 to 384 km. We find that the rate of nuclear burning depends on the number of ignition points at early times, the density of ignition points at intermediate times, and the radius of the confining sphere at late times. The results depend primarily on the number of ignition points, but we do not expect this to be the case in general. The simulations with few ignition points release more nuclear energy E nuc , have larger kinetic energies E K , and produce more 56 Ni than those with many ignition points, and differ in the distribution of 56 Ni, Si, and C/O in the ejecta. For these reasons, the simulations with few ignition points exhibit higher peak B-band absolute magnitudes M B and light curves that rise and decline more quickly; their M B and light curves resemble those of under-luminous SNe Iax, while those for simulations with many ignition points are not.
Kinney, Melissa A; Hookway, Tracy A; Wang, Yun; McDevitt, Todd C
2014-02-01
The physiochemical stem cell microenvironment regulates the delicate balance between self-renewal and differentiation. The three-dimensional assembly of stem cells facilitates cellular interactions that promote morphogenesis, analogous to the multicellular, heterotypic tissue organization that accompanies embryogenesis. Therefore, expansion and differentiation of stem cells as multicellular aggregates provides a controlled platform for studying the biological and engineering principles underlying spatiotemporal morphogenesis and tissue patterning. Moreover, three-dimensional stem cell cultures are amenable to translational screening applications and therapies, which underscores the broad utility of scalable suspension cultures across laboratory and clinical scales. In this review, we discuss stem cell morphogenesis in the context of fundamental biophysical principles, including the three-dimensional modulation of adhesions, mechanics, and molecular transport and highlight the opportunities to employ stem cell spheroids for tissue modeling, bioprocessing, and regenerative therapies.
The three-dimensional leading-edge vortex of a "hovering' model hawkmoth
van den Berg, C.; Ellington, C.P.
1997-01-01
Recent flow visualization experiments with the hawkmoth, Manduca sexta, revealed a small but clear leading-edge vortex and a pronounced three-dimensional flow. Details of this flow pattern were studied with a scaled-up, robotic insect ('the flapper') that accurately mimicked the wing movements of a
Coupling reducing k-points for supercell models of defects in three-dimensional photonic crystals
DEFF Research Database (Denmark)
Lægsgaard, Jesper; Bjarklev, Anders Overgaard
2004-01-01
The optimum choice of k-point for supercell calculations of defect states in a three-dimensional photonic crystal is investigated for the case of a supercell with a simple cubic (SC) structure. By using the k-point (1/4,1/4,1/4) it is possible to eliminate the symmetric part of the repeated...
Montessori, A; Falcucci, G; Prestininzi, P; La Rocca, M; Succi, S
2014-05-01
We investigate the accuracy and performance of the regularized version of the single-relaxation-time lattice Boltzmann equation for the case of two- and three-dimensional lid-driven cavities. The regularized version is shown to provide a significant gain in stability over the standard single-relaxation time, at a moderate computational overhead.
Directory of Open Access Journals (Sweden)
A. V. Krasnyuk
2008-03-01
Full Text Available Three-dimensional design possibilities of the AutoCAD system for performing graphic tasks are presented in the article. On the basis of the studies conducted the features of application of computer-aided design system are noted and the methods allowing to decrease considerably the quantity of errors at making the drawings are offered.
Yufeng, Guo; Zhigong, Wang; Gene, Sheu
2009-11-01
This paper presents an analytical three-dimensional breakdown model of SOI lateral power devices with a circular layout. The Poisson equation is solved in cylindrical coordinates to obtain the radial surface potential and electric field distributions for both fully- and partially-depleted drift regions. The breakdown voltages for N+N and P+N junctions are derived and employed to investigate the impact of cathode region curvature. A modified RESURF criterion is proposed to provide a design guideline for optimizing the breakdown voltage and doping concentration in the drift region in three dimensional space. The analytical results agree well with MEDICI simulation results and experimental data from earlier publications.
Sergovich, Aimée; Johnson, Marjorie; Wilson, Timothy D
2010-01-01
The anatomy of the pelvis is complex, multilayered, and its three-dimensional organization is conceptually difficult for students to grasp. The aim of this project was to create an explorable and projectable stereoscopic, three-dimensional (3D) model of the female pelvis and pelvic contents for anatomical education. The model was created using cryosection images obtained from the Visible Human Project, in conjunction with a general-purpose three-dimensional segmentation and surface-rendering program. Anatomical areas of interest were identified and labeled on consecutive images. Each 2D slice was reassembled, forming a three-dimensional model. The model includes the pelvic girdle, organs of the pelvic cavity, surrounding musculature, the perineum, neurovascular structures, and the peritoneum. Each structure can be controlled separately (e.g. added, subtracted, made transparent) to reveal organization and/or relationships between structures. The model can be manipulated and/or projected stereoscopically to visualize structures and relationships from different angles with excellent spatial perception. Because of its ease of use and versatility, we expect this model may provide a powerful teaching tool for learning in the classroom or in the laboratory. (c) 2010 American Association of Anatomists.
Directory of Open Access Journals (Sweden)
Efstathia Papafragkou
Full Text Available Human noroviruses are the most common cause of acute gastroenteritis worldwide. Recently, cell culture systems have been described using either human embryonic intestinal epithelial cells (Int-407 or human epithelial colorectal adenocarcinoma cells (Caco-2 growing on collagen-I porous micro carrier beads in a rotating bioreactor under conditions of physiological fluid shear. Here, we describe the efforts from two independent laboratories to implement this three dimensional (3D cell culture system for the replication of norovirus. Int-407 and Caco-2 were grown in a rotating bioreactor for up to 28 days. Prior to infection, cells were screened for the presence of microvilli by electron microscopy and stained for junction proteins (zonula occludens-1, claudin-1, and β-catenin. Differentiated 3D cells were transferred to 24-well plates and infected with bacteria-free filtrates of various norovirus genotypes (GI.1, GI.3, GI.8, GII.2, GII.4, GII.7, and GII.8. At 12 h, 24 h, and 48 h post inoculation, viral RNA from both cells and supernatants were collected and analyzed for norovirus RNA by real-time reverse transcription PCR. Despite observations of high expression of junction proteins and microvilli development in stained thin sections, our data suggest no significant increase in viral titer based on norovirus RNA copy number during the first 48 h after inoculation for the different samples and virus culture conditions tested. Our combined efforts demonstrate that 3D cell culture models using Int-407 or Caco-2 cells do not support norovirus replication and highlight the complexity and difficulty of developing a reproducible in vitro cell culture system for human norovirus.
Modeling of three-dimensional diffusible resistors with the one-dimensional tube multiplexing method
International Nuclear Information System (INIS)
Gillet, Jean-Numa; Degorce, Jean-Yves; Meunier, Michel
2009-01-01
Electronic-behavior modeling of three-dimensional (3D) p + -π-p + and n + -ν-n + semiconducting diffusible devices with highly accurate resistances for the design of analog resistors, which are compatible with the CMOS (complementary-metal-oxide-semiconductor) technologies, is performed in three dimensions with the fast tube multiplexing method (TMM). The current–voltage (I–V) curve of a silicon device is usually computed with traditional device simulators of technology computer-aided design (TCAD) based on the finite-element method (FEM). However, for the design of 3D p + -π-p + and n + -ν-n + diffusible resistors, they show a high computational cost and convergence that may fail with fully non-separable 3D dopant concentration profiles as observed in many diffusible resistors resulting from laser trimming. These problems are avoided with the proposed TMM, which divides the 3D resistor into one-dimensional (1D) thin tubes with longitudinal axes following the main orientation of the average electrical field in the tubes. The I–V curve is rapidly obtained for a device with a realistic 3D dopant profile, since a system of three first-order ordinary differential equations has to be solved for each 1D multiplexed tube with the TMM instead of three second-order partial differential equations in the traditional TCADs. Simulations with the TMM are successfully compared to experimental results from silicon-based 3D resistors fabricated by laser-induced dopant diffusion in the gaps of MOSFETs (metal-oxide-semiconductor field-effect transistors) without initial gate. Using thin tubes with other shapes than parallelepipeds as ring segments with toroidal lateral surfaces, the TMM can be generalized to electronic devices with other types of 3D diffusible microstructures
Three dimensional models in uro-oncology: a future built with additive fabrication.
Manning, Todd G; O'Brien, Jonathan S; Christidis, Daniel; Perera, Marlon; Coles-Black, Jasamine; Chuen, Jason; Bolton, Damien M; Lawrentschuk, Nathan
2018-04-01
Three-dimensional (3D) printing was invented in 1983 but has only just begun to influence medicine and surgery. Conversion of digital images into physical models demonstrates promise to revolutionize multiple domains of surgery. In the field of uro-oncology, researchers and clinicians have recognized the potential of this technology and are working towards making it an integral part of urological practice. We review current literature regarding 3D printing and other 3D technology in the field of urology. A comprehensive assessment of contemporary literature was performed according to a modified PRISMA analysis for the purposes of this narrative review article. Medical databases that were searched included: Web of Science, EMBASE and Cochrane databases. Articles assessed were limited only to English-language peer-reviewed articles published between 1980 and 2017. The search terms used were "3D", "3-dimensional", "printing", "printing technology", "urology", "surgery". Acceptable articles were reviewed and incorporated for their merit and relevance with preference given for articles with high impact, original research and recent advances. Thirty-five publications were included in final analysis and discussion. The area of 3D printing in Urology shows promising results, but further research is required and cost reduction must occur before clinicians fully embrace its use. As costs continue to decline and diversity of materials continues to expand, research and clinical utilization will increase. Recent advances have demonstrated the potential of this technology in the realms of education and surgical optimization. The generation of personalized organs using 3D printing scaffolding remains the 'holy grail' of this technology.
Effects of a three-dimensional hill on the wake characteristics of a model wind turbine
Yang, Xiaolei; Howard, Kevin B.; Guala, Michele; Sotiropoulos, Fotis
2015-02-01
The spatial evolution of a turbine wake downwind of a three-dimensional sinusoidal hill is studied using large-eddy simulations and wind tunnel measurements. The computed flow fields behind the hill show good agreement with wind tunnel measurements. Three different heights of the hill, i.e., hhill = zh - 0.5D, ≈ zh and =zh + 0.5D (where zh is the turbine hub height and D is the diameter of the turbine rotor), were considered. The effect of the hill turbine spacing was investigated through a comparative analysis with the turbine wake results in the undisturbed turbulent boundary layer. It is observed that the turbine wakes downwind of the hill with hhill ≈ zh and hhill = zh + 0.5D recover faster because of the increased entrainment of ambient flow into the turbine wake, which is due to the enhanced turbulent transport in both spanwise and vertical directions. In comparison with the turbine only case, significant increases in the turbulence kinetic energy (TKE) in the turbine wake are observed for the hill-turbine cases with hhill ≈ zh and hhill = zh + 0.5D. A velocity scale UT, defined in terms of the thrust force acting on the turbine, is introduced for the turbine-added velocity deficit and TKE. For the turbine-added velocity deficit, UT is shown to be an appropriate scale at wake locations sufficiently far downwind of the turbine (i.e., greater than or equal to 8D). The vertical profiles of the turbine-added TKE normalized by UT 2 are shown to nearly collapse in the wake both for the turbine only and hill-turbine cases at all locations greater than 4D downwind of the turbine. A simple model for the turbine-added TKE in complex terrain is also proposed based on the new physical insights obtained from our simulations.
Low Doses of Celecoxib Stimulate Human Endometrium Growth in A Three-Dimensional Culture Model
Directory of Open Access Journals (Sweden)
Mohammad Rasool Khazaei
2013-01-01
Full Text Available Background: The endometrium plays a pivotal role in implantation and pregnancy. CyclooxygenaseII (COX-2 has an important function in biological processes such as cellproliferation and inflammation. Celecoxib is a selective inhibitor of COX-2 with numerouspharmacologic functions. The aim of present study is to investigate the effects ofcelecoxib on the human endometrium in a three-dimensional (3D culture model.Materials and Methods: In this experimental study, normal human endometria (n=10obtained from reproductive age women were cut into 1×1 mm sections. Endometrialexplants were placed between two layers of fibrin gel. To create the fibrin gel, we poureda thin layer of fibrinogen solution [3 mg/ml in medium 199 (M199] into each well of a24-well culture dish and added thrombin enzyme. Endometrial fragments were placed inthe center of each well and covered with a second layer of fibrinogen solution. M199 supplementedwith L-glutamine, fetal bovine serum (FBS, 5% and antibiotics were addedto each well. The media in each experimental well contained either1, 10 or 50 μM ofcelecoxib. At the end of the study, we calculated endometrial tissue growth changes byscoring methods and determined the percentage of angiogenesis. Data were analyzed bythe Kruskal-Wallis method. P<0.05 was considered significant.Results: The growth scores were as follows: control (1.37 ± 0.16, 1 μM (1.96 ± 0.28,10 μM (2.01 ± 0.25, and 50 μM (1.17 ± 0.14 celecoxib, all of which were significantlydifferent. The angiogenesis percentages were: 25.56 ± 6.72% (control, 31.98 ± 6.18% (1μM, 42.67 ± 7.27% (10 μM and 23.44 ± 4.03% (50 μM, which were not significantlydifferent from each other.
A bio-inspired device for drag reduction on a three-dimensional model vehicle.
Kim, Dongri; Lee, Hoon; Yi, Wook; Choi, Haecheon
2016-03-10
In this paper, we introduce a bio-mimetic device for the reduction of the drag force on a three-dimensional model vehicle, the Ahmed body (Ahmed et al 1984 SAE Technical Paper 840300). The device, called automatic moving deflector (AMD), is designed inspired by the movement of secondary feathers on bird's wing suction surface: i.e., secondary feathers pop up when massive separation occurs on bird's wing suction surface at high angles of attack, which increases the lift force at landing. The AMD is applied to the rear slanted surface of the Ahmed body to control the flow separation there. The angle of the slanted surface considered is 25° at which the drag coefficient on the Ahmed body is highest. The wind tunnel experiment is conducted at Re H = 1.0 × 10(5)-3.8 × 10(5), based on the height of the Ahmed body (H) and the free-stream velocity (U ∞). Several AMDs of different sizes and materials are tested by measuring the drag force on the Ahmed body, and showed drag reductions up to 19%. The velocity and surface-pressure measurements show that AMD starts to pop up when the pressure in the thin gap between the slanted surface and AMD is much larger than that on the upper surface of AMD. We also derive an empirical formula that predicts the critical free-stream velocity at which AMD starts to operate. Finally, it is shown that the drag reduction by AMD is mainly attributed to a pressure recovery on the slanted surface by delaying the flow separation and suppressing the strength of the longitudinal vortices emanating from the lateral edges of the slanted surface.
Komatsu, K; Abe, Y; Yoshioka, T; Ishimura, H; Ebihara, A; Suda, H
2014-01-01
The purpose of this study was to evaluate the accuracy of diagnosing vertical root fractures (VRFs) by comparing the volume of bone defects in VRFs with those in non-VRFs on reconstructed three-dimensional (3D) models (TDMs) using CBCT. 32 maxillary pre-molars and anterior teeth with radiolucent areas were evaluated on pre-operative CBCT images. Of the 32 teeth, 16 had a fractured root (VRF group) and 16 had a non-fractured root (non-VRF group). The radiolucent area of each tooth was traced in each dimension [mesiodistal, buccolingual and horizontal (the apicoincisal aspect)] by two observers, and 3D images were reconstructed with the Amira(®) software (Visage Imaging Inc., Richmond, Australia). The volume, V, of the TDM was divided into the coronal side and the periapical side at the horizontal slice through the apical foramen, and v was defined as the volume of the coronal side. The values of v/V were calculated for all cases. The Mann-Whitney U test was used to compare values between the VRF group and the non-VRF group (p < 0.05). A receiver operating characteristic (ROC) curve was constructed to select the optimal cut-point. There was a statistically significant difference in the value of v/V between the two groups (p < 0.05). With a cut-point derived from the ROC curve, and the sensitivity, specificity and accuracy of predicting the VRFs were 1.00, 0.75 and 0.88, respectively. Lesions resulting from VRFs can be distinguished from those of non-VRFs on 3D CBCT images with a high degree of accuracy, based on their different 3D shapes.
Fatone, Stefania; Johnson, William Brett; Tucker, Kerice
2016-04-01
Misalignment of an articulated ankle-foot orthosis joint axis with the anatomic joint axis may lead to discomfort, alterations in gait, and tissue damage. Theoretical, two-dimensional models describe the consequences of misalignments, but cannot capture the three-dimensional behavior of ankle-foot orthosis use. The purpose of this project was to develop a model to describe the effects of ankle-foot orthosis ankle joint misalignment in three dimensions. Computational simulation. Three-dimensional scans of a leg and ankle-foot orthosis were incorporated into a link segment model where the ankle-foot orthosis joint axis could be misaligned with the anatomic ankle joint axis. The leg/ankle-foot orthosis interface was modeled as a network of nodes connected by springs to estimate interface pressure. Motion between the leg and ankle-foot orthosis was calculated as the ankle joint moved through a gait cycle. While the three-dimensional model corroborated predictions of the previously published two-dimensional model that misalignments in the anterior -posterior direction would result in greater relative motion compared to misalignments in the proximal -distal direction, it provided greater insight showing that misalignments have asymmetrical effects. The three-dimensional model has been incorporated into a freely available computer program to assist others in understanding the consequences of joint misalignments. Models and simulations can be used to gain insight into functioning of systems of interest. We have developed a three-dimensional model to assess the effect of ankle joint axis misalignments in ankle-foot orthoses. The model has been incorporated into a freely available computer program to assist understanding of trainees and others interested in orthotics. © The International Society for Prosthetics and Orthotics 2014.
Yoshida, Masaki
2010-06-01
Characteristic tectonic structures such as young orogenic belts and suture zones in a continent are expected to be mechanically weaker than the stable part of the continental lithosphere with the cratonic root (or cratonic lithosphere) and yield lateral viscosity variations in the continental lithosphere. In the present-day Earth's lithosphere, the pre-existing, mechanically weak zones emerge as a diffuse plate boundary. However, the dynamic role of a weak (low-viscosity) continental margin (WCM) in the stability of continental lithosphere has not been understood in terms of geophysics. Here, a new numerical simulation model of mantle convection with a compositionally and rheologically heterogeneous, deformable, mobile continental lithosphere is presented for the first time by using three-dimensional regional spherical-shell geometry. A compositionally buoyant and highly viscous continental assemblage with pre-existing WCMs, analogous to the past supercontinent, is modeled and imposed on well-developed mantle convection whose vigor of convection, internal heating rate, and rheological parameters are appropriate for the Earth's mantle. The visco-plastic oceanic lithosphere and the associated subduction of oceanic plates are incorporated. The time integration of the advection of continental materials with zero chemical diffusion is performed by a tracer particle method. The time evolution of mantle convection after setting the model supercontinent is followed over 800 Myr. Earth-like continental drift is successfully reproduced, and the characteristic thermal interaction between the mantle and the continent/supercontinent is observed in my new numerical model. Results reveal that the WCM protects the cratonic lithosphere from being stretched by the convecting mantle and may play a significant role in the stability of the cratonic lithosphere during the geological timescale because it acts as a buffer that prevents the cratonic lithosphere from undergoing global
Directory of Open Access Journals (Sweden)
Kazuyuki Yusa
2017-06-01
Full Text Available Objectives: Recently, three-dimensional printing models based on preoperative computed tomography and magnetic resonance imaging images have been widely used in medical fields. This study presents an effective use of the three-dimensional printing model in exploring complex spatial relationship between the tumour and surrounding tissue and in simulation surgery based planning of the operative procedure. Material and Methods: The patient was a 7-year-old boy with ameloblastic fibro-odontoma. Prior to surgery, a hybrid three-dimensional printing model consisting of the jaw bone, the tumour and the inferior alveolar nerve was fabricated. After the simulation surgery based on this model, enucleation of the tumour, leaving tooth 46 intact (Universal Numbering System by ADA safe, was planned. Results: Enucleation of the tumour was successfully carried out. One year later, healing was found to be satisfactory both clinically and radiographically. Conclusions: The study presented an effective application of a novel hybrid three-dimensional printing model composed of hard and soft tissues. Such innovations can bring significant benefits, especially to the field of oncological surgery.
Taher, Fadi; Falkensammer, Juergen; McCarte, Jamie; Strassegger, Johann; Uhlmann, Miriam; Schuch, Philipp; Assadian, Afshin
2017-06-01
The fenestrated Anaconda endograft (Vascutek/Terumo, Inchinnan, UK) is intended for the treatment of abdominal aortic aneurysms with an insufficient infrarenal landing zone. The endografts are custom-made with use of high-resolution, 1-mm-slice computed tomography angiography images. For every case, a nonsterile prototype and a three-dimensional (3D) model of the patient's aorta are constructed to allow the engineers as well as the physician to test-implant the device and to review the fit of the graft. The aim of this investigation was to assess the impact of 3D model construction and prototype testing on the design of the final sterile endograft. A prospectively held database on fenestrated endovascular aortic repair patients treated at a single institution was completed with data from the Vascutek engineers' prototype test results as well as the product request forms. Changes to endograft design based on prototype testing were assessed and are reported for all procedures. Between April 1, 2013, and August 18, 2015, 60 fenestrated Anaconda devices were implanted. Through prototype testing, engineers were able to identify and report potential risks to technical success related to use of the custom device for the respective patient. Theoretical concerns about endograft fit in the rigid model were expressed in 51 cases (85.0%), and the engineers suggested potential changes to the design of 21 grafts (35.0%). Thirteen cases (21.7%) were eventually modified after the surgeon's testing of the prototype. A second prototype was ordered in three cases (5.0%) because of extensive changes to endograft design, such as inclusion of an additional fenestration. Technical success rates were comparable for grafts that showed a perfect fit from the beginning and cases in which prototype testing resulted in a modification of graft design. Planning and construction of fenestrated endografts for complex aortic anatomies where exact fit and positioning of the graft are paramount to
Three-Dimensional Numerical Modeling of Crustal Growth at Active Continental Margins
Zhu, G.; Gerya, T.; Tackley, P. J.
2011-12-01
Active margins are important sites of new continental crust formation by magmatic processes related to the subduction of oceanic plates. We investigate these phenomena using a three-dimensional coupled petrological-geochemical-thermomechanical numerical model, which combines a finite-difference flow solver with a non-diffusive marker-in-cell technique for advection (I3ELVIS code, Gerya and Yuen, PEPI,2007). The model includes mantle flow associated with the subducting plate, water release from the slab, fluid propagation that triggers partial melting at the slab surface, melt extraction and the resulting volcanic crustal growth at the surface. The model also accounts for variations in physical properties (mainly density and viscosity) of both fluids and rocks as a function of local conditions in temperature, pressure, deformation, nature of the rocks, and chemical exchanges. Our results show different patterns of crustal growth and surface topography, which are comparable to nature, during subduction at active continental margins. Often, two trench-parallel lines of magmatic activity, which reflect two maxima of melt production atop the slab, are formed on the surface. The melt extraction rate controls the patterns of new crust at different ages. Moving free water reflects the path of fluids, and the velocity of free water shows the trend of two parallel lines of magmatic activity. The formation of new crust in particular time intervals is distributed in finger-like shapes, corresponding to finger-like and ridge-like cold plumes developed atop the subducting slabs (Zhu et al., G-cubed,2009; PEPI,2011). Most of the new crust is basaltic, formed from peridotitic mantle. Granitic crust extracted from melted sediment and upper crust forms in a line closer to the trench, and its distribution reflects the finger-like cold plumes. Dacitic crust extracted from the melted lower crust forms in a line farther away from the trench, and its distribution is anticorrelated with
Cytocompatibility of Biodentine using a three-dimensional cell culture model.
Silva, E J N L; Senna, P M; De-Deus, G; Zaia, A A
2016-06-01
To evaluate the cytotoxic effects of Biodentine, using a three-dimensional (3D) cell culture associated with an in situ root-end filling experimental model. White mineral trioxide aggregate (MTA) and zinc oxide cement were used as reference for comparison. IL-1α and TNF-α cytokine production were also evaluated. The root canals of 24 human maxillary incisor teeth were prepared using a single-file reciprocating technique. After root filling, a 3-mm root-end resection was performed and 3 mm of gutta-percha was removed from the canal. The teeth were randomly distributed to receive one of the following root-end filling materials: Biodentine, white MTA or zinc oxide cement (positive control group). In the negative control group, the root canal was not retro-filled. The cytocompatibility of the materials was evaluated using the methyl-thiazol-diphenyl-tetrazolium (MTT) assay in an in situ root-end filling experimental model. Balb/c 3T3 fibroblasts, cultured in rat tail collagen type I 3D scaffold, were exposed to the root apex for 24 h, and cell viability was measured by means of reduction MTT salt. IL-1α and TNF-α production were analysed using enzyme-linked immunosorbent assay. One-way analysis of variance was performed and, when the F-ratios were significant, data were compared by Duncan's multiple-range test. The alpha-type error was set at 0.05. Biodentine and MTA groups had similar cell activity to the negative control group (P > 0.05), indicating low cytotoxicity for both materials. The stronger cytotoxicity effect was identified on the zinc oxide cement (P Biodentine and the negative control group were observed for TNF-α (P > 0.05); however, both MTA and Biodentine were associated with overproduction of IL-1α when compared to the control group (P Biodentine and MTA had similar cytocompatibility in a 3D cell culture model associated with an in situ root-end filling model. The methodology could be used as an alternative to assess the
Keating, Thomas; Barnett, Michael; Barab, Sasha A.; Hay, Kenneth E.
2002-01-01
Describes the Virtual Solar System (VSS) course which is one of the first attempts to integrate three-dimensional (3-D) computer modeling as a central component of introductory undergraduate education. Assesses changes in student understanding of astronomy concepts as a result of participating in an experimental introductory astronomy course in…
Hansen, John; Barnett, Michael; MaKinster, James; Keating, Thomas
2004-01-01
In this study, we explore an alternate mode for teaching and learning the dynamic, three-dimensional (3D) relationships that are central to understanding astronomical concepts. To this end, we implemented an innovative undergraduate course in which we used inexpensive computer modeling tools. As the second of a two-paper series, this report…
DEFF Research Database (Denmark)
Christensen, I T; Jørgensen, Flemming Steen; Svensson, L A
1993-01-01
Three-dimensional structures of the enzyme phospholipase A2 (PLA2) from human pancreas and from human synovial fluid were constructed by model building based on high-resolution X-ray crystallographic structures and homology considerations. The structure of the human pancreatic PLA2 was based...
Goffart, D.; Wal, D.J. van der; Klomp, E.M.; Hoogstraten, H.W.; Janssen, L.P.B.M.; Breysse, L.; Trolez, Y.
1996-01-01
A three-dimensional modeling of the transporting elements in a self-wiping corotating twin-screw extruder has been carried out by using the finite element package Sepran. This simulation uses the 3D geometry of the channel rolled over the twin-screw, which consists of the intermeshing and normal
2017-11-01
pages were written in JavaScript to allow the user to run those Fortran90 and C executable programs as mentioned in the previous section to: 1) produce...documentation/ javascript . Huynh G, Wang Y, Williamson C. Building and vegetation rasterization for the three-dimensional wind field (3DWF) model. Aberdeen
Oortgiesen, D.A.W.; Yu, N.; Bronckers, A.L.; Yang, F.; Walboomers, X.F.; Jansen, J.A.
2012-01-01
Periodontitis is a disease affecting the supporting structures of the teeth, which can eventually result in tooth loss. A three-dimensional (3D) tissue culture model was developed that may serve to grow a 3D construct that not only transplants into defective periodontal sites, but also allows to
Oortgiesen, D.A.W.; Yu, N.; Bronckers, A.L.J.J.; Yang, F.; Walboomers, X.F.; Jansen, J.A.
2012-01-01
Periodontitis is a disease affecting the supporting structures of the teeth, which can eventually result in tooth loss. A three-dimensional (3D) tissue culture model was developed that may serve to grow a 3D construct that not only transplants into defective periodontal sites, but also allows to
Song-Gui Chen; Chuan-Hu Zhang; Yun-Tian Feng; Qi-Cheng Sun; Feng Jin
2016-01-01
This paper presents a three-dimensional (3D) parallel multiple-relaxation-time lattice Boltzmann model (MRT-LBM) for Bingham plastics which overcomes numerical instabilities in the simulation of non-Newtonian fluids for the Bhatnagar–Gross–Krook (BGK) model. The MRT-LBM and several related mathematical models are briefly described. Papanastasiou’s modified model is incorporated for better numerical stability. The impact of the relaxation parameters of the model is studied in detail. The MRT-L...
Three-Dimensional Thermal Modeling of Dry Spent Nuclear Fuel Storage Canisters
International Nuclear Information System (INIS)
Lee, S.Y.
1998-05-01
One of the interim storage configurations being considered for aluminum-clad foreign research reactor fuel, such as the Material and Testing Reactor (MTR) design, is a dry storage facility. To support design studies of storage options, a computational and experimental program was conducted at the Savannah River Site (SRS). The objective was to develop computational fluid dynamics (CFD) conjugate models which would be benchmarked using data obtained from a full scale heat transfer experiment conducted in the SRS Experimental Thermal Fluids Laboratory. The current work describes the modeling approach and presents comparison of computational results with experimental data. The experimental set up consists of an instrumented fuel canister 16 inches in diameter and 36 inches in height.The canister contains a sealed fuel can which is designed to store four fuel assemblies. The fuel assembly heat generation is simulated by an imbeded electrical heater. Each fuel assembly is separated from the others by a stainless steel grid and the assemblies can communicate thermal-hydraulically only through narrow slot holes located at the top and bottom of the assembly. The flow within an enclosed canister is a buoyancy-induced motion resulting from body force acting on density gradients which arise from fluid temperature gradients. The canister is filled with helium or nitrogen gas. The heated canister is surrounded by five unheated dummy canisters and is located inside a wind tunnel. During the test, data are obtained for the radial and axial heat flux/temperature profiles inside the canister, air velocity outside the canister, and ambient air temperature. CFD approach has been used to model the three-dimensional convective velocity and temperature distributions within a single dry storage canister of MTR fuel elements.The final analysis was made for the cases with internal heat source of 85 to 138 watts per MTR fuel element (equivalent to 22 to 35 kW/m3) using various different
Three-Dimensional Super-Resolution: Theory, Modeling, and Field Tests Results
Bulyshev, Alexander; Amzajerdian, Farzin; Roback, Vincent E.; Hines, Glenn; Pierrottet, Diego; Reisse, Robert
2014-01-01
Many flash lidar applications continue to demand higher three-dimensional image resolution beyond the current state-of-the-art technology of the detector arrays and their associated readout circuits. Even with the available number of focal plane pixels, the required number of photons for illuminating all the pixels may impose impractical requirements on the laser pulse energy or the receiver aperture size. Therefore, image resolution enhancement by means of a super-resolution algorithm in near real time presents a very attractive solution for a wide range of flash lidar applications. This paper describes a superresolution technique and illustrates its performance and merits for generating three-dimensional image frames at a video rate.
Frahm, Jan-Michael; Pollefeys, Marc Andre Leon; Gallup, David Robert
2015-12-08
Methods of generating a three dimensional representation of an object in a reference plane from a depth map including distances from a reference point to pixels in an image of the object taken from a reference point. Weights are assigned to respective voxels in a three dimensional grid along rays extending from the reference point through the pixels in the image based on the distances in the depth map from the reference point to the respective pixels, and a height map including an array of height values in the reference plane is formed based on the assigned weights. An n-layer height map may be constructed by generating a probabilistic occupancy grid for the voxels and forming an n-dimensional height map comprising an array of layer height values in the reference plane based on the probabilistic occupancy grid.
Maidment, Susannah C R; Bates, Karl T; Falkingham, Peter L; VanBuren, Collin; Arbour, Victoria; Barrett, Paul M
2014-08-01
Ornithischian dinosaurs were primitively bipedal with forelimbs modified for grasping, but quadrupedalism evolved in the clade on at least three occasions independently. Outside of Ornithischia, quadrupedality from bipedal ancestors has only evolved on two other occasions, making this one of the rarest locomotory transitions in tetrapod evolutionary history. The osteological and myological changes associated with these transitions have only recently been documented, and the biomechanical consequences of these changes remain to be examined. Here, we review previous approaches to understanding locomotion in extinct animals, which can be broadly split into form-function approaches using analogy based on extant animals, limb-bone scaling, and computational approaches. We then carry out the first systematic attempt to quantify changes in locomotor muscle function in bipedal and quadrupedal ornithischian dinosaurs. Using three-dimensional computational modelling of the major pelvic locomotor muscle moment arms, we examine similarities and differences among individual taxa, between quadrupedal and bipedal taxa, and among taxa representing the three major ornithischian lineages (Thyreophora, Ornithopoda, Marginocephalia). Our results suggest that the ceratopsid Chasmosaurus and the ornithopod Hypsilophodon have relatively low moment arms for most muscles and most functions, perhaps suggesting poor locomotor performance in these taxa. Quadrupeds have higher abductor moment arms than bipeds, which we suggest is due to the overall wider bodies of the quadrupeds modelled. A peak in extensor moment arms at more extended hip angles and lower medial rotator moment arms in quadrupeds than in bipeds may be due to a more columnar hindlimb and loss of medial rotation as a form of lateral limb support in quadrupeds. We are not able to identify trends in moment arm evolution across Ornithischia as a whole, suggesting that the bipedal ancestry of ornithischians did not constrain the
International Nuclear Information System (INIS)
Wei Xin; Xie Xiaodong; Wang Chaohua
2007-01-01
Objective: To establish virtual three-dimensional instrument and cerebral aneurysm models by using three-dimensional moulding software, and to explore the effect of the models in interventional preoperative simulation. Methods: The virtual individual models including cerebral arteries and aneurysms were established by using the three-dimensional moulding software of 3D Studio MAX R3 based on standard virtual cerebral aneurysm models and individual DSA image. The virtual catheter, guide wire, stent and coil were also established. The study of interventional preoperative simulation was run in personal computer, and included 3 clinical cases. Results: The simulation results of the working angle and the moulding angle of the head of catheter and guide wire in 3 cases were identical with that of operation results. The simulation results of the requirement of number and size of coil in 1 case of anterior communicating aneurysm and 1 case of posterior communicating aneurysm were identical with that of operation results. The simulation results of coil for aneurysmal shape in 1 case of giant internal carotid artery aneurysm were more than 2 three-dimensional coils with size of 3 mm x 3 cm from the operation results, and the position of the second coil in aneurysmal neck was adjusted according to the results of real-time simulation. The results of retrospective simulation of operation procedure indicated that the simulation methods for regular and small aneurysms could become a routine simulation means but more simulation experience was needed to build up for the giant aneurysms. Conclusions: The virtual three-dimensional instrument and cerebral aneurysm models established by the general software provided a new study method for neuro-interventional preoperative simulation, and it played an important guidance role in developing neuro-interventional operation. (authors)
THREE-DIMENSIONAL NONLINEAR FINITE ELEMENT MODELING FOR LATERALLY LOADED VERTICAL PILES
Directory of Open Access Journals (Sweden)
M. Kubilay KELESOĞLU
2006-01-01
Full Text Available This paper presents a study for laterally loaded free head concrete piles using the finite element method (FEM. The finite element mesh is constituted from three-dimensional elements. The pile and soil boundary are defined cylindrically while lateral load is defined as single concentrated load from the top of the pile head. Various types of soil and pile properties are analysed and the load-deformation curves for different types of soils namely, sands and clays are evaluated.
Three-dimensional finite element modelling of the uniaxial tension test
DEFF Research Database (Denmark)
Østergaard, Lennart; Stang, Henrik
2002-01-01
. One of the most direct methods for determination of the σ-w relationship is the uniaxial tension test, where a notched specimen is pulled apart while the tensile load and the crack opening displacement is observed. This method is appealing since the interpretation is straightforward. The method...... is examined in this paper through three dimensional finite element analyses. It is concluded that the interpretation of the uniaxial tension test is indeed straightforward, if the testing machine stiffness is sufficiently high....
Lindsay, M. D.; Ailleres, L.; Jessell, Mark; de Kemp, E. A.; Betts, P. G.
2012-01-01
Geological three-dimensional (3D) models are constructed to reliably represent a given geological target. The reliability of a model is heavily dependent on the input data and is sensitive to uncertainty. This study examines the uncertainty introduced by geological orientation data by producing a suite of implicit 3d models generated from orientation measurements subjected to uncertainty simulations. The resulting uncertainty associated with different regions of the geological model can be lo...
International Nuclear Information System (INIS)
Nagai, Haruyasu; Yamazawa, Hiromi
1994-11-01
A three-dimensional atmospheric dynamic model (PHYSIC) was improved and its performance was examined using the meteorological data observed at a coastal area with a complex terrain. To introduce synoptic meteorological conditions into the model, the initial and boundary conditions were improved. By this improvement, the model can predict the temporal change of wind field for more than 24 hours. Moreover, the model successfully simulates the land and sea breeze observed at Shimokita area in the summer of 1992. (author)
Beam halo studies using a three-dimensional particle-core model
Directory of Open Access Journals (Sweden)
Ji Qiang
2000-06-01
Full Text Available In this paper we present a study of beam halo based on a three-dimensional particle-core model of an ellipsoidal bunched beam in a constant focusing channel including the effects of nonlinear rf focusing. For an initially mismatched beam, three linear envelope modes—a high frequency mode, a low frequency mode, and a quadrupole mode—are identified for an azimuthally symmetric bunched beam. The high frequency mode has three components all in phase; the low frequency mode has the transverse components in phase and the longitudinal component 180° out of phase; the quadrupole mode has no longitudinal component, and the two transverse components in the mode are 180° out of phase. We also study the case of an ellipsoidal bunched beam without azimuthal symmetry and find that the high frequency mode and the low frequency mode are still present but the quadrupole mode is replaced by a new mode with transverse components 180° out of phase and a nonzero longitudinal component. Previous studies, which generally addressed the situation where the longitudinal-to-transverse focusing strength is roughly 0.6 or less, conclude that the oscillation of the high frequency mode is predominantly transverse, and that of the low frequency mode is predominantly longitudinal. In this paper we present a systematic study of the features of the modes as a function of the longitudinal-to-transverse focusing strength ratio. We find that, when the ratio is greater than unity, the high frequency mode may contain a significant longitudinal component. Thus, excitation of the high frequency mode in this situation can be responsible for the formation of longitudinal beam halo. Furthermore, while previous studies have observed halo amplitudes roughly 2–3 times the matched beam edge, for the present parameters we observe much larger amplitudes (5 times or more. This is due to the fact that the longitudinal-to-transverse focusing ratio used here is greater than that of previous
Computational methods for a three-dimensional model of the petroleum-discovery process
Schuenemeyer, J.H.; Bawiec, W.J.; Drew, L.J.
1980-01-01
A discovery-process model devised by Drew, Schuenemeyer, and Root can be used to predict the amount of petroleum to be discovered in a basin from some future level of exploratory effort: the predictions are based on historical drilling and discovery data. Because marginal costs of discovery and production are a function of field size, the model can be used to make estimates of future discoveries within deposit size classes. The modeling approach is a geometric one in which the area searched is a function of the size and shape of the targets being sought. A high correlation is assumed between the surface-projection area of the fields and the volume of petroleum. To predict how much oil remains to be found, the area searched must be computed, and the basin size and discovery efficiency must be estimated. The basin is assumed to be explored randomly rather than by pattern drilling. The model may be used to compute independent estimates of future oil at different depth intervals for a play involving multiple producing horizons. We have written FORTRAN computer programs that are used with Drew, Schuenemeyer, and Root's model to merge the discovery and drilling information and perform the necessary computations to estimate undiscovered petroleum. These program may be modified easily for the estimation of remaining quantities of commodities other than petroleum. ?? 1980.
Holland, Scott D.; Murphy, Kelly J.
1993-01-01
Since mission profiles for airbreathing hypersonic vehicles such as the National Aero-Space Plane include single-stage-to-orbit requirements, real gas effects may become important with respect to engine performance. The effects of the decrease in the ratio of specific heats have been investigated in generic three-dimensional sidewall compression scramjet inlets with leading-edge sweep angles of 30 and 70 degrees. The effects of a decrease in ratio of specific heats were seen by comparing data from two facilities in two test gases: in the Langley Mach 6 CF4 Tunnel in tetrafluoromethane (where gamma=1.22) and in the Langley 15-Inch Mach 6 Air Tunnel in perfect gas air (where gamma=1.4). In addition to the simulated real gas effects, the parametric effects of cowl position, contraction ratio, leading-edge sweep, and Reynolds number were investigated in the 15-Inch Mach 6 Air Tunnel. The models were instrumented with a total of 45 static pressure orifices distributed on the sidewalls and baseplate. Surface streamline patterns were examined via oil flow, and schlieren videos were made of the external flow field. The results of these tests have significant implications to ground based testing of inlets in facilities which do not operate at flight enthalpies.
Morris, Kevin Peter
thinning and extraction) and manual interpretation techniques are used to identify a set of 'geological primitives' (linear or arc features representing lithological boundaries) within these data. Inclusion of the DEM data provides the three-dimensional co-ordinates of these primitives enabling a least-squares fit to be employed to calculate dip and strike values, based, initially, on the assumption of a simple, linearly dipping structural model. A very large number of scene 'primitives' is identified using these procedures, only some of which have geological significance. Knowledge-based rules are therefore used to identify the relevant. For example, rules are developed to identify lake edges, forest boundaries, forest tracks, rock-vegetation boundaries, and areas of geomorphological interest. Confidence in the geological significance of some of the geological primitives is increased where they are found independently in both the DEM and remotely sensed data. The dip and strike values derived in this way are compared to information taken from the published geological map for this area, as well as measurements taken in the field. Many results are shown to correspond closely to those taken from the map and in the field, with an error of < 1°. These data and rules are incorporated into an expert system which, initially, produces a simple model of the geological structure. The system also provides a graphical user interface for manual control and interpretation, where necessary. Although the system currently only allows a relatively simple structural model (linearly dipping with faulting), in the future it will be possible to extend the system to model more complex features, such as anticlines, synclines, thrusts, nappes, and igneous intrusions.
Directory of Open Access Journals (Sweden)
F. Tsai
2014-06-01
Full Text Available This paper briefly presents two approaches for effective three-dimensional (3D building model reconstruction from terrestrial laser scanning (TLS data and single perspective view imagery and assesses their applicability to the reconstruction of 3D models of landmark or historical buildings. The collected LiDAR point clouds are registered based on conjugate points identified using a seven-parameter transformation system. Three dimensional models are generated using plan and surface fitting algorithms. The proposed single-view reconstruction (SVR method is based on vanishing points and single-view metrology. More detailed models can also be generated according to semantic analysis of the façade images. Experimental results presented in this paper demonstrate that both TLS and SVR approaches can successfully produce accurate and detailed 3D building models from LiDAR point clouds or different types of single-view perspective images.
Modeling a TRIGA Mark II reactor using the Attila three-dimensional deterministic transport code
International Nuclear Information System (INIS)
Keller, S.T.; Palmer, T.S.; Wareing, T.A.
2005-01-01
A benchmark model of a TRIGA reactor constructed using materials and dimensions similar to existing TRIGA reactors was analyzed using MCNP and the recently developed deterministic transport code Attila TM . The benchmark reactor requires no MCNP modeling approximations, yet is sufficiently complex to validate the new modeling techniques. Geometric properties of the benchmark reactor are specified for use by Attila TM with CAD software. Materials are treated individually in MCNP. Materials used in Attila TM that are clad are homogenized. Attila TM uses multigroup energy discretization. Two cross section libraries were constructed for comparison. A 16 group library collapsed from the SCALE 4.4.a 238 group library provided better results than a seven group library calculated with WIMS-ANL. Values of the k-effective eigenvalue and scalar flux as a function of location and energy were calculated by the two codes. The calculated values for k-effective and spatially averaged neutron flux were found to be in good agreement. Flux distribution by space and energy also agreed well. Attila TM results could be improved with increased spatial and angular resolution and revised energy group structure. (authors)
International Nuclear Information System (INIS)
Bernard, J.P.; Haekkinen, J.; Sarkomaa, P.
1997-01-01
A number of numerical studies on three-dimensional flows in reactor vessels of nuclear power plants have been carried out recently. The main reason for this is the phenomenon of inherent boron dilution. These studies have been done for Loviisa nuclear power plant as well. This presentation focuses on the three dimensional modeling of Loviisa's lower plenum with the commercial CFX code. The investigations particularly deal with the modeling of the two perforated plates located at the bottom and just below the core of the vessel. The perforated plates can be modeled as porous media in the CFX code. The model has been validated against available experimental data. Velocity profiles around the plates, the pressure drop through the plates, and the simulation of mixing factors have been investigated specifically. (author)
Three-dimensional radiative transfer modeling using the control volume finite element method
International Nuclear Information System (INIS)
Grissa, H.; Askri, F.; Ben Salah, M.; Ben Nasrallah, S.
2007-01-01
In the present study, a three-dimensional algorithm for the treatment of radiative heat transfer in emitting, absorbing and scattering media is developed. The approach is based on the utilization of control volume finite element method (CVFEM) which, to the knowledge of the authors, is applied at the first time to 3D radiative heat transfer in participating media. The accuracy of the present algorithm is tested by comparing its predictions to other published works. Comparisons show that CVFEM produces good results. Moreover, this approach permits compatibility with other numerical methods used for computational fluids mechanics problems
Modelling three-dimensional beta sources for skin dose calculations using VARSKIN Mod 2
International Nuclear Information System (INIS)
Durham, J.S.; Reece, W.D.
1991-01-01
The computer code VARSKIN Mod 1 has been modified to include three-dimensional sources and insertion of layers of protective clothing between the source and the skin. The new code, VARSKIN Mod 2, is described, and the sensitivity of the dose to source geometry, diameter, thickness, density, and protective clothing thickness are presented for low, intermediate, and high energy beta emitters. Finally, doses calculated using VARSKIN Mod 2 are compared with dose measured from hot particles found in nuclear power plants. The results indicate that VARSKIN Mod 2 will greatly improve the accuracy of hot particle dosimetry. (author)
Lee, S. S.; Nwadike, E. V.; Sinha, S. E.
1982-01-01
The theory of a three dimensional (3-D) mathematical thermal discharge model and a related one dimensional (1-D) model are described. Model verification at two sites, a separate user's manual for each model are included. The 3-D model has two forms: free surface and rigid lid. The former allows a free air/water interface and is suited for significant surface wave heights compared to mean water depth, estuaries and coastal regions. The latter is suited for small surface wave heights compared to depth because surface elevation was removed as a parameter. These models allow computation of time dependent velocity and temperature fields for given initial conditions and time-varying boundary conditions. The free surface model also provides surface height variations with time.
Goodwin, T. J.; Coate-Li, L.; Linnehan, R. M.; Hammond, T. G.
2000-01-01
This study established two- and three-dimensional renal proximal tubular cell cultures of the endangered species bowhead whale (Balaena mysticetus), developed SV40-transfected cultures, and cloned the 61-amino acid open reading frame for the metallothionein protein, the primary binding site for heavy metal contamination in mammals. Microgravity research, modulations in mechanical culture conditions (modeled microgravity), and shear stress have spawned innovative approaches to understanding the dynamics of cellular interactions, gene expression, and differentiation in several cellular systems. These investigations have led to the creation of ex vivo tissue models capable of serving as physiological research analogs for three-dimensional cellular interactions. These models are enabling studies in immune function, tissue modeling for basic research, and neoplasia. Three-dimensional cellular models emulate aspects of in vivo cellular architecture and physiology and may facilitate environmental toxicological studies aimed at elucidating biological functions and responses at the cellular level. Marine mammals occupy a significant ecological niche (72% of the Earth's surface is water) in terms of the potential for information on bioaccumulation and transport of terrestrial and marine environmental toxins in high-order vertebrates. Few ex vivo models of marine mammal physiology exist in vitro to accomplish the aforementioned studies. Techniques developed in this investigation, based on previous tissue modeling successes, may serve to facilitate similar research in other marine mammals.
Energy Technology Data Exchange (ETDEWEB)
Bibb, Richard [Department of Design and Technology, Loughborough University, Ashby Road, Loughborough, Leicestershire LE11 3TU (United Kingdom)], E-mail: r.j.bibb@lboro.ac.uk; Winder, John [Health and Rehabilitation Sciences Research Institute, University of Ulster, Shore Road, Newtownabbey, BT37 0QB (United Kingdom)], E-mail: rj.winder@ulster.ac.uk
2010-02-15
This technical note aims to raise awareness amongst radiographers of the application of Computed Tomography data in the production of models using Rapid Prototyping technologies. It also aims to provide radiographers with recommendations that will assist them in providing three-dimensional Computed Tomography data that can fulfil the requirements of medical modelling. Potential problem areas in data acquisition and transfer are discussed and suggestions are given for methods that aim to avoid these.
Directory of Open Access Journals (Sweden)
Khansa Rubab
Full Text Available This letter investigates the MHD three-dimensional flow of upper-convected Maxwell (UCM fluid over a bi-directional stretching surface by considering the Cattaneo-Christov heat flux model. This model has tendency to capture the characteristics of thermal relaxation time. The governing partial differential equations even after employing the boundary layer approximations are non linear. Accurate analytic solutions for velocity and temperature distributions are computed through well-known homotopy analysis method (HAM. It is noticed that velocity decreases and temperature rises when stronger magnetic field strength is accounted. Penetration depth of temperature is a decreasing function of thermal relaxation time. The analysis for classical Fourier heat conduction law can be obtained as a special case of the present work. To our knowledge, the Cattaneo-Christov heat flux model law for three-dimensional viscoelastic flow problem is just introduced here.
Rubab, Khansa; Mustafa, M
2016-01-01
This letter investigates the MHD three-dimensional flow of upper-convected Maxwell (UCM) fluid over a bi-directional stretching surface by considering the Cattaneo-Christov heat flux model. This model has tendency to capture the characteristics of thermal relaxation time. The governing partial differential equations even after employing the boundary layer approximations are non linear. Accurate analytic solutions for velocity and temperature distributions are computed through well-known homotopy analysis method (HAM). It is noticed that velocity decreases and temperature rises when stronger magnetic field strength is accounted. Penetration depth of temperature is a decreasing function of thermal relaxation time. The analysis for classical Fourier heat conduction law can be obtained as a special case of the present work. To our knowledge, the Cattaneo-Christov heat flux model law for three-dimensional viscoelastic flow problem is just introduced here.
Hase, Kazunori; Obuchi, Shuichi
The three-dimensional entire-body neuro-musculo-skeletal model generating normal walking motion was modified to synthesize pathological walking including asymmetricalcompensatorymotions. Inadditiontotheneuronalparameters, musculo-skeletal parameters were employed as search parameters to represent affected musculo-skeletal systems. This model successfully generated pathological walking patterns, such as walking by a person with one lower extremity shorter than the other and walking by a person with an affected gluteus medius muscle. The simulated walking patterns were of the entire body, three-dimensional, continuous and asymmetrical, and demonstrated the characteristics of actual pathological walking. The walking model with an artificial foot also predicted not only the walking pattern adapted to the artificial foot but also the design parameters of the artificial foot adapted to the effective walking pattern simultaneously. Such simulation methods will establish a novel methodology that we call computational rehabilitation engineering.
Karlin, Lawrence; Weinstock, Peter; Hedequist, Daniel; Prabhu, Sanjay P
2017-07-01
This study was carried out to evaluate the benefits of personalized three-dimensional printing as an aid to the performance of surgery for the correction of spinal deformity in children with myelomeningocele. We performed a retrospective review to include all such children for whom personalized three-dimensional spine models were used for surgical planning (group A) and compared them through subjective and objective criteria to a similar group that had no models (group B). The seven children in group A were younger and had more complex deformities than the 10 children in group B. The models provided a markedly improved appreciation of the complex anatomy and enabled the planning and performance of patient-specific spinal instrumentation that was secure and low profile. The efficiency of the surgery as measured by intraoperative fluoroscopy time and blood loss and the extent of the deformity correction was comparable or superior in group A.
Aksenova, Olesya; Nikolaeva, Evgenia; Cehlár, Michal
2017-11-01
This work aims to investigate the effectiveness of mathematical and three-dimensional computer modeling tools in the planning of processes of fuel and energy complexes at the planning and design phase of a thermal power plant (TPP). A solution for purification of gas emissions at the design development phase of waste treatment systems is proposed employing mathematical and three-dimensional computer modeling - using the E-nets apparatus and the development of a 3D model of the future gas emission purification system. Which allows to visualize the designed result, to select and scientifically prove economically feasible technology, as well as to ensure the high environmental and social effect of the developed waste treatment system. The authors present results of a treatment of planned technological processes and the system for purifying gas emissions in terms of E-nets. using mathematical modeling in the Simulink application. What allowed to create a model of a device from the library of standard blocks and to perform calculations. A three-dimensional model of a system for purifying gas emissions has been constructed. It allows to visualize technological processes and compare them with the theoretical calculations at the design phase of a TPP and. if necessary, make adjustments.
A three-dimensional mathematical model for the signal propagation on a neuron’s membrane.
Directory of Open Access Journals (Sweden)
Konstantinos eXylouris
2015-07-01
Full Text Available In order to be able to examine the extracellular potential's influence on network activity and to better understand dipole properties of the extracellular potential, we present and analyze a three-dimensional formulation of the cable equation which facilitates numeric simulations.When the neuron's intra- and extracellular space is assumed to be purely resistive (i.e. no free charges, the balance law of electric fluxes leads to the Laplace equation for the distribution of the intra- and extracellular potential. Moreover, the flux across the neuron's membrane is continuous. This observation already delivers the three dimensional cable equation. The coupling of the intra- and extracellular potential over the membrane is not trivial. Here, we present a continuous extension of the extracellular potential to the intracellular space and combine the resulting equation with the intracellular problem. This approach makes the system numerically accessible.On the basis of the assumed pure resistive intra- and extracellular spaces, we conclude that a cell's out-flux balances out completely. As a consequence neurons do not own any current monopoles. We present a rigorous analysis with spherical harmonics for the extracellular potential by approximating the neuron's geometry to a sphere. Furthermore, we show with first numeric simulations on idealized circumstances that the extracellular potential can have a decisive effect on network activity through ephaptic interactions.
Biofabrication of a three-dimensional liver micro-organ as an in vitro drug metabolism model
International Nuclear Information System (INIS)
Chang, Robert; Sun Wei; Emami, Kamal; Wu Honglu
2010-01-01
In their normal in vivo matrix milieu, tissues assume complex well-organized three-dimensional architectures. Therefore, the primary aim in the tissue engineering design process is to fabricate an optimal analog of the in vivo scenario. This challenge can be addressed by applying emerging layered biofabrication approaches in which the precise configuration and composition of cells and bioactive matrix components can recapitulate the well-defined three-dimensional biomimetic microenvironments that promote cell-cell and cell-matrix interactions. Furthermore, the advent of and refinements in microfabricated systems can present physical and chemical cues to cells in a controllable and reproducible fashion unmatched with conventional cultures, resulting in the precise construction of engineered biomimetic microenvironments on the cellular length scale in geometries that are readily parallelized for high throughput in vitro models. As such, the convergence of layered solid freeform fabrication (SFF) technologies along with microfabrication techniques enables the creation of a three-dimensional micro-organ device to serve as an in vitro platform for cell culture, drug screening or to elicit further biological insights, particularly for NASA's interest in a flight-suitable high-fidelity microscale platform to study drug metabolism in space and planetary environments. The proposed model in this paper involves the combinatorial setup of an automated syringe-based, layered direct cell writing bioprinting process with micro-patterning techniques to fabricate a microscale in vitro device housing a chamber of bioprinted three-dimensional liver cell-encapsulated hydrogel-based tissue constructs in defined design patterns that biomimic the cell's natural microenvironment for enhanced biological functionality. In order to assess the structural formability and biological feasibility of such a micro-organ, reproducibly fabricated tissue constructs were biologically characterized for
Directory of Open Access Journals (Sweden)
Marco Giorgio Bevilacqua
2016-03-01
Full Text Available In the field of documentation and preservation of cultural heritage, there is keen interest in 3D metric viewing and rendering of architecture for both formal appearance and color. On the other hand, operative steps of restoration interventions still require full-scale, 2D metric surface representations. The transition from 3D to 2D representation, with the related geometric transformations, has not yet been fully formalized for planar development of frescoed vaults. Methodologies proposed so far on this subject provide transitioning from point cloud models to ideal mathematical surfaces and projecting textures using software tools. The methodology used for geometry and texture development in the present work does not require any dedicated software. The different processing steps can be individually checked for any error introduced, which can be then quantified. A direct accuracy check of the planar development of the frescoed surface has been carried out by qualified restorers, yielding a result of 3 mm. The proposed methodology, although requiring further studies to improve automation of the different processing steps, allowed extracting 2D drafts fully usable by operators restoring the vault frescoes.
Directory of Open Access Journals (Sweden)
Budrukkar Ashwini
2008-01-01
Full Text Available Aims and Objectives: To study the geometric uncertainties in the treatment and evaluate the adequacy of the margins employed for planning target volume (PTV generation in the treatment of focal conformal radiotherapy (CRT for patients with brain tumors treated with different head support systems. Materials and Methods: The study population included 11 patients with brain tumors who were to be treated with CRT. Contrast-enhanced planning CT scan (5-mm spacing and reconstructed to 2 mm of brain were performed. Five patients were immobilized using neck support only (NR-only and six patients had neck support with flexion (NRF, the form of immobilization being decided by the likely beam arrangements to be employed for that particular patient. The data was transferred to the planning system (CadPlan where three-dimensional conformal radiation therapy was planned. Digitally reconstructed radiographs (DRRs were created for the orthogonal portals with the fixed field sizes of 10 x 10 taken at the isocenter. Treatment verification was done using an amorphous silicon detector portal imaging device for using orthogonal portals and the DRR was used as a reference image. An image matching software was used to match the anatomical landmarks in the DRR and the portal imaging and the displacement of the portals in x, y axis and rotation were noted in the anteroposterior (AP and lateral images. Electronic portal imaging was repeated twice weekly and an average of 8-14 images per patient was recorded. The mean deviation in all the directions was calculated for the each patient. Comparison of setup errors between the two head support systems was done. Results: A total 224 images were studied in anterior and lateral portals. The patient group with NR-only had 100 images, while the NRF group had 124 images. The mean total error in all patients, NR-only group, and NRF group was 0.33 mm, 0.24 mm, and 0.79 mm in the mediolateral (ML direction; 1.16 mm, 0.14 mm, and 2
Three-dimensional modelling and numerical optimisation of the W7-X ICRH antenna
Energy Technology Data Exchange (ETDEWEB)
Louche, F., E-mail: fabrice.louche@rma.ac.be [Laboratoire de physique des plasmas de l’ERM, Laboratorium voor plasmafysica van de KMS (LPP-ERM/KMS), Ecole Royale Militaire, Koninklijke Militaire School, Brussels (Belgium); Křivská, A.; Messiaen, A.; Ongena, J. [Laboratoire de physique des plasmas de l’ERM, Laboratorium voor plasmafysica van de KMS (LPP-ERM/KMS), Ecole Royale Militaire, Koninklijke Militaire School, Brussels (Belgium); Borsuk, V. [Institute of Energy and Climate Research – Plasma Physics, Forschungszentrum Juelich (Germany); Durodié, F.; Schweer, B. [Laboratoire de physique des plasmas de l’ERM, Laboratorium voor plasmafysica van de KMS (LPP-ERM/KMS), Ecole Royale Militaire, Koninklijke Militaire School, Brussels (Belgium)
2015-10-15
Highlights: • A simplified version of the ICRF antenna for the stellarator W7-X has been modelled with the 3D electromagnetic software Microwave Studio. This antenna can be tuned between 25 and 38 MHz with the help of adjustable capacitors. • In previous modellings the front of the antenna was modelled with the help of 3D codes, while the capacitors were modelled as lumped elements with a given DC capacitance. As this approach does not take into account the effect of the internal inductance, a MWS model of these capacitors has been developed. • The initial geometry does not permit the operation at 38 MHz. By modifying some geometrical parameters of the front face, it was possible to increase the frequency band of the antenna, and to increase (up to 25%) the maximum coupled power accounting for the technical constraints on the capacitors. • The W7-X ICRH antenna must be operated at 25 and 38 MHz, and for various toroidal phasings of the strap RF currents. Due to the considered duty cycle it is shown that thanks to a special procedure based on minimisation techniques, it is possible to define a satisfactory optimum geometry in agreement with the specifications of the capacitors. • The various steps of the optimisation are validated with TOPICA simulations. For a given density profile the RF power coupling expectancy can be precisely computed. - Abstract: Ion Cyclotron Resonance Heating (ICRH) is a promising heating and wall conditioning method considered for the W7-X stellarator and a dedicated ICRH antenna has been designed. This antenna must perform several tasks in a long term physics programme: fast particles generation, heating at high densities, current drive and ICRH physics studies. Various minority heating scenarios are considered and two frequency bands will be used. In the present work a design for the low frequency range (25–38 MHz) only is developed. The antenna is made of 2 straps with tap feeds and tuning capacitors with DC capacitance in
Fortova, S. V.; Utkin, P. S.; Pronina, A. P.; Narkunas, T. S.; Shepelev, V. V.
2018-01-01
The work is devoted to the development of the authors software package Turbulence Problem Solver originally created for the study of three-dimensional problems of hydrodynamic instabilities. Mathematical model is based on the three-dimensional two-component Euler equations, the numerical algorithm is based on the grid-characteristics scheme of the second approximation order in space. The functionality of the mathematical model and the numerical algorithm of the package is extended to consider the problem of high-speed metallic plates impact. The detailed description of the proposed numerical approach is presented. The problem of high-speed metallic plates impact is solved using stiffened gas equation of state. The parameters of the equation of state are calibrated on the basis of computational results obtained with the use of wide-range equations of states for the metals.
Marloes A. Huis; Nina Hansen; Sabine Otten; Robert Lensink; Robert Lensink
2017-01-01
Women’s empowerment is an important goal in achieving sustainable development worldwide. Offering access to microfinance services to women is one way to increase women’s empowerment. However, empirical evidence provides mixed results with respect to its effectiveness. We reviewed previous research on the impact of microfinance services on different aspects of women’s empowerment. We propose a Three-Dimensional Model of Women’s Empowerment to integrate previous findings and to gain a deeper un...
Huis, Marloes A.; Hansen, Nina; Otten, Sabine; Lensink, Robert
2017-01-01
Women's empowerment is an important goal in achieving sustainable development worldwide. Offering access to microfinance services to women is one way to increase women's empowerment. However, empirical evidence provides mixed results with respect to its effectiveness. We reviewed previous research on the impact of microfinance services on different aspects of women's empowerment. We propose a Three-Dimensional Model of Women's Empowerment to integrate previous findings and to gain a deeper un...
Modelling stratospheric chemistry in a global three-dimensional chemical transport model
Energy Technology Data Exchange (ETDEWEB)
Rummukainen, M. [Finnish Meteorological Inst., Sodankylae (Finland). Sodankylae Observatory
1995-12-31
Numerical modelling of atmospheric chemistry aims to increase the understanding of the characteristics, the behavior and the evolution of atmospheric composition. These topics are of utmost importance in the study of climate change. The multitude of gases and particulates making up the atmosphere and the complicated interactions between them affect radiation transfer, atmospheric dynamics, and the impacts of anthropogenic and natural emissions. Chemical processes are fundamental factors in global warming, ozone depletion and atmospheric pollution problems in general. Much of the prevailing work on modelling stratospheric chemistry has so far been done with 1- and 2-dimensional models. Carrying an extensive chemistry parameterisation in a model with high spatial and temporal resolution is computationally heavy. Today, computers are becoming powerful enough to allow going over to 3-dimensional models. In order to concentrate on the chemistry, many Chemical Transport Models (CTM) are still run off-line, i.e. with precalculated and archived meteorology and radiation. In chemistry simulations, the archived values drive the model forward in time, without interacting with the chemical evolution. This is an approach that has been adopted in stratospheric chemistry modelling studies at the Finnish Meteorological Institute. In collaboration with the University of Oslo, a development project was initiated in 1993 to prepare a stratospheric chemistry parameterisation, fit for global 3-dimensional modelling. This article presents the parameterisation approach. Selected results are shown from basic photochemical simulations
House, Michael; McCabe, Reid; Socrate, Simona
2013-01-01
Preterm birth affects over 12% of all pregnancies in the United States for an annual healthcare cost of $26 billion. Preterm birth is a multifactorial disorder but cervical abnormalities are a prominent feature in many patients. Women with a short cervix are known to be at increased risk for preterm birth and a short cervix is used to target therapy to prevent preterm birth. Although the clinical significance of a short cervix is well known, the three-dimensional anatomical changes that lead to cervical shortening are poorly understood. Here, we review our previous studies of the three-dimensional anatomy of the cervix and uterus during pregnancy. The rationale for these studies was to improve our understanding of the deformation mechanisms leading to cervical shortening. Both magnetic resonance imaging and three-dimensional (3D) ultrasound were used to obtain anatomical data in healthy, pregnant volunteers. Solid models were constructed from the 3D imaging data. These solid models were used to create numerical models suitable for biomechanical simulation. Three simulations were studied: cervical funneling, uterine growth, and fundal pressure. These simulations showed that cervical changes are a complex function of the tissue properties of the cervical stroma, the loading conditions associated with pregnancy and the 3D anatomical geometry of the cervix and surrounding structures. An improved understanding of these cervical changes could point to new approaches to prevent undesired cervical shortening. This new insight should lead to therapeutic strategies to delay or prevent preterm birth. Copyright © 2012 Wiley Periodicals, Inc.
Coupling reducing k-points for supercell models of defects in three-dimensional photonic crystals
DEFF Research Database (Denmark)
Lægsgaard, Jesper; Bjarklev, Anders Overgaard
2004-01-01
The optimum choice of k-point for supercell calculations of defect states in a three-dimensional photonic crystal is investigated for the case of a supercell with a simple cubic (SC) structure. By using the k-point (1/4,1/4,1/4) it is possible to eliminate the symmetric part of the repeated......-image couplings for the first three neighbour shells in the SC lattice. This result is shown to hold also for the case of non-equivalent axes (e.g. a distorted lattice, or an asymmetric defect structure). A specific example of a donor defect in a woodpile structure demonstrates that use of this k-point can lead...
International Nuclear Information System (INIS)
Kobayashi, Yoko; Aiyoshi, Eitaro
2001-01-01
Fast and accurate prediction of three-dimensional (3D) power distribution is essential in a boiling water reactor (BWR). The prediction method of 3D power distribution in BWR is developed using the neural network. Application of the neural network starts with selecting the learning algorithm. In the proposed method, we use the learning algorithms based on a class of Quasi-Newton optimization techniques called Self-Scaling Variable Metric (SSVM) methods. Prediction studies were done for a core of actual BWR plant with octant symmetry. Compared to classical Quasi-Newton methods, it is shown that the SSVM method reduces the number of iterations in the learning mode. The results of prediction demonstrate that the neural network can predict 3D power distribution of BWR reasonably well. The proposed method will be very useful for BWR loading pattern optimization problems where 3D power distribution for a huge number of loading patterns (LPs) must be performed. (author)
Energy Technology Data Exchange (ETDEWEB)
Marghany, Maged [Universiti Teknologi Malaysia, Skudai, Johor Bahru (Malaysia). Inst. for Science and Technology Geospatial (INSTeG)
2012-06-15
This work presents a new approach for three-dimensional (3D) coastal deformation simulation using differential synthetic aperture interferometry (DInSAR). In doing so, conventional InSAR procedures are implemented to three repeat passes of RADARSAT-1 SAR fine mode data (F1). Further, the DInSAR method is implemented with the phase unwrapping technique. Consequently, DInSAR is used to eliminate the phase decorrelation impact from the interferograms. The study shows the accurate performance of DInSAR with a root mean square error of 0.02 {+-} 0.21 m and 90% confidence intervals. In conclusion, the DInSAR technique produces an accurate 3D coastal geomorphology reconstruction. (orig.)
Three-dimensional radar imaging of buildings based on computer models
Dogaru, Traian; Liao, DaHan; Le, Calvin
2013-05-01
This paper describes the study of a through-the-wall radar system for three-dimensional (3-D) building imaging, based on computer simulations. Two possible configurations are considered, corresponding to an airborne spotlight and a ground-based strip-map geometry. The paper details all the steps involved in this analysis: creating the computational meshes, calculating the radar signals scattered by the target, forming the radar images, and processing the images for visualization and interpretation. Particular attention is given to the scattering phenomenology and its dependence on the system geometry. The images are created via the backprojection algorithm and further processed using a constant falsealarm rate (CFAR) detector. We discuss methods of 3-D image visualization and interpretation of the results.
Three-dimensional FEM model of FBGs in PANDA fibers with experimentally determined model parameters
Lindner, Markus; Hopf, Barbara; Koch, Alexander W.; Roths, Johannes
2017-04-01
A 3D-FEM model has been developed to improve the understanding of multi-parameter sensing with Bragg gratings in attached or embedded polarization maintaining fibers. The material properties of the fiber, especially Young's modulus and Poisson's ratio of the fiber's stress applying parts, are crucial for accurate simulations, but are usually not provided by the manufacturers. A methodology is presented to determine the unknown parameters by using experimental characterizations of the fiber and iterative FEM simulations. The resulting 3D-Model is capable of describing the change in birefringence of the free fiber when exposed to longitudinal strain. In future studies the 3D-FEM model will be employed to study the interaction of PANDA fibers with the surrounding materials in which they are embedded.
Nakanishi, A.; Shimomura, N.; Kodaira, S.; Obana, K.; Takahashi, T.; Yamamoto, Y.; Yamashita, M.; Takahashi, N.; Kaneda, Y.
2012-12-01
In the Nankai Trough subduction seismogenic zone, the Nankai and Tonankai earthquakes had often occurred simultaneously, and caused a great event. In order to reduce a great deal of damage to coastal area from both strong ground motion and tsunami generation, it is necessary to understand rupture synchronization and segmentation of the Nankai megathrust earthquake. For a precise estimate of the rupture zone of the Nankai megathrust event based on the knowledge of realistic earthquake cycle and variation of magnitude, it is important to know the geometry and property of the plate boundary of the subduction seismogenic zone. To improve a physical model of the Nankai Trough seismogenic zone, the large-scale high-resolution wide-angle and reflection (MCS) seismic study, and long-term observation has been conducted since 2008. Marine active source seismic data have been acquired along grid two-dimensional profiles having the total length of ~800km every year. A three-dimensional seismic tomography using active and passive seismic data observed both land and ocean bottom stations have been also performed. From those data, we found that several strong lateral variations of the subducting Philippine Sea plate and overriding plate corresponding to margins of coseismic rupture zone of historical large event occurred along the Nankai Trough. Particularly a possible prominent reflector for the forearc Moho is recently imaged in the offshore side in the Kii channel at the depth of ~18km which is shallower than those of other area along the Nankai Trough. Such a drastic variation of the overriding plate might be related to the existence of the segmentation of the Nankai megathrust earthquake. Based on our results derived from seismic studies, we have tried to make a geometrical model of the Philippine Sea plate and a three-dimensional velocity structure model of the Nankai Trough seismogenic zone. In this presentation, we will summarize major results of out seismic studies, and
DEFF Research Database (Denmark)
Olchev, A.; Radler, K.; Sogachev, Andrey
2009-01-01
A three-dimensional model Mixfor-3D of soil–vegetation–atmosphere transfer (SVAT) was developed and applied to estimate possible effects of tree clear-cutting on radiation and soil temperature regimes of a forest ecosystem. The Mixfor-3D model consists of several closely coupled 3D sub...... and soil temperature profiles showed that the model adequately describes the spatial heterogeneity and dynamics of these variables under different weather conditions. The model can be used to explore solar radiation and soil temperature patterns within heterogeneous forest plots, with applications...
Energy Technology Data Exchange (ETDEWEB)
Sato, T.; Matsuoka, T. [Japan Petroleum Exploration Corp., Tokyo (Japan); Saeki, T. [Japan National Oil Corp., Tokyo (Japan). Technology Research Center
1997-05-27
Discussed in this report is a wavefield simulation in the 3-dimensional seismic survey. With the level of the object of exploration growing deeper and the object more complicated in structure, the survey method is now turning 3-dimensional. There are several modelling methods for numerical calculation of 3-dimensional wavefields, such as the difference method, pseudospectral method, and the like, all of which demand an exorbitantly large memory and long calculation time, and are costly. Such methods have of late become feasible, however, thanks to the advent of the parallel computer. As compared with the difference method, the pseudospectral method requires a smaller computer memory and shorter computation time, and is more flexible in accepting models. It outputs the result in fullwave just like the difference method, and does not cause wavefield numerical variance. As the computation platform, the parallel computer nCUBE-2S is used. The object domain is divided into the number of the processors, and each of the processors takes care only of its share so that parallel computation as a whole may realize a very high-speed computation. By the use of the pseudospectral method, a 3-dimensional simulation is completed within a tolerable computation time length. 7 refs., 3 figs., 1 tab.
DEFF Research Database (Denmark)
Shapiro, Alexander A.
2018-01-01
A new three-dimensional hydrodynamic model for unsteady two-phase flows in a porous medium, accounting for the motion of the interface between the flowing liquids, is developed. In a minimum number of interpretable geometrical assumptions, a complete system of macroscale flow equations is derived......, their expansion or contraction is also described, while rotation has been proven negligible. A detailed comparison with the previous studies for the two-phase flows accounting for propagation of the interface on micro- and macroscale has been carried out. A numerical algorithm has been developed allowing...... by averaging the microscale equations for viscous flow. The macroscale flow velocities of the phases may be non-parallel, while the interface between them is, on average, inclined to the directions of the phase velocities, as well as to the direction of the saturation gradient. The last gradient plays...
Directory of Open Access Journals (Sweden)
Wong Kelvin KL
2012-02-01
Full Text Available Abstract Background This study characterizes the distribution and components of plaque structure by presenting a three-dimensional blood-vessel modelling with the aim of determining mechanical properties due to the effect of lipid core and calcification within a plaque. Numerical simulation has been used to answer how cap thickness and calcium distribution in lipids influence the biomechanical stress on the plaque. Method Modelling atherosclerotic plaque based on structural analysis confirms the rationale for plaque mechanical examination and the feasibility of our simulation model. Meaningful validation of predictions from modelled atherosclerotic plaque model typically requires examination of bona fide atherosclerotic lesions. To analyze a more accurate plaque rupture, fluid-structure interaction is applied to three-dimensional blood-vessel carotid bifurcation modelling. A patient-specific pressure variation is applied onto the plaque to influence its vulnerability. Results Modelling of the human atherosclerotic artery with varying degrees of lipid core elasticity, fibrous cap thickness and calcification gap, which is defined as the distance between the fibrous cap and calcification agglomerate, form the basis of our rupture analysis. Finite element analysis shows that the calcification gap should be conservatively smaller than its threshold to maintain plaque stability. The results add new mechanistic insights and methodologically sound data to investigate plaque rupture mechanics. Conclusion Structural analysis using a three-dimensional calcified model represents a more realistic simulation of late-stage atherosclerotic plaque. We also demonstrate that increases of calcium content that is coupled with a decrease in lipid core volume can stabilize plaque structurally.
2012-01-01
Background This study characterizes the distribution and components of plaque structure by presenting a three-dimensional blood-vessel modelling with the aim of determining mechanical properties due to the effect of lipid core and calcification within a plaque. Numerical simulation has been used to answer how cap thickness and calcium distribution in lipids influence the biomechanical stress on the plaque. Method Modelling atherosclerotic plaque based on structural analysis confirms the rationale for plaque mechanical examination and the feasibility of our simulation model. Meaningful validation of predictions from modelled atherosclerotic plaque model typically requires examination of bona fide atherosclerotic lesions. To analyze a more accurate plaque rupture, fluid-structure interaction is applied to three-dimensional blood-vessel carotid bifurcation modelling. A patient-specific pressure variation is applied onto the plaque to influence its vulnerability. Results Modelling of the human atherosclerotic artery with varying degrees of lipid core elasticity, fibrous cap thickness and calcification gap, which is defined as the distance between the fibrous cap and calcification agglomerate, form the basis of our rupture analysis. Finite element analysis shows that the calcification gap should be conservatively smaller than its threshold to maintain plaque stability. The results add new mechanistic insights and methodologically sound data to investigate plaque rupture mechanics. Conclusion Structural analysis using a three-dimensional calcified model represents a more realistic simulation of late-stage atherosclerotic plaque. We also demonstrate that increases of calcium content that is coupled with a decrease in lipid core volume can stabilize plaque structurally. PMID:22336469
International Nuclear Information System (INIS)
Bernhardt, P.A.
1979-01-01
A time-varying model of neutral gas expansion in a nonuniform environment is developed. The model includes diffusion in a multicomponent atmosphere, chemical reactions between the diffusing gases and the atmosphere, thermal diffusion effects, and transport due to altitude-dependent winds. The three-dimensional diffusion equation governing the neutral gas flow is solved numerically using Fourier transform and finite difference techniques. Examples of H 2 , OH, and CO 2 diffusion illustrate the effects of chemical reactions and wind shears on the neutral expansion. The model may be applied to chemical releases which produce ionospheric depletions or luminescent trails
Finite element analysis of three dimensional crack growth by the use of a boundary element sub model
DEFF Research Database (Denmark)
Lucht, Tore
2009-01-01
A new automated method to model non-planar three dimensional crack growth is proposed which combines the advantages of both the boundary element method and the finite element method. The proposed method links the two methods by a submodelling strategy in which the solution of a global finite...... element model containing an approximation of the crack is interpolated to a much smaller boundary element model containing a fine discretization of the real crack. The method is validated through several numerical comparisons and by comparison to crack growth measured in a test specimen for an engineering...
Similarity reduction of a three-dimensional model of the far turbulent wake behind a towed body
Schmidt, Alexey
2011-12-01
Semi-empirical three-dimensional model of turbulence in the approximation of the far turbulent wake behind a towed body in a passively stratified medium is considered. The sought-for quantities of the model are the velocity defect, kinetic turbulent energy, kinetic energy dissipation rate, averaged density defect and density fluctuation variance. The full group of transformations admitted by this model is found. The governing equations are reduced into ordinary differential equations by similarity reduction and method of the B-determining equations (BDE method). System of ordinary differential equations was solved numerically. The obtained solutions agree with experimental data.
Ott, Mark; Yang, J; Barilla, J.; Crabbe, A.; Sarker, S. F.; Liu, Y.
2017-01-01
Three-dimensional/3-D organotypic models of human intestinal epithelium mimic the differentiated form and function of parental tissues often not exhibited by 2-D monolayers and respond to Salmonella in ways that reflect in vivo infections. To further enhance the physiological relevance of 3-D models to more closely approximate in vivo intestinal microenvironments during infection, we developed and validated a novel 3-D intestinal co-culture model containing multiple epithelial cell types and phagocytic macrophages, and applied to study enteric infection by different Salmonella pathovars.
A three-dimensional (3D) analytical model for subthreshold characteristics of uniformly doped FinFET
Tripathi, Shweta; Narendar, Vadthiya
2015-07-01
In this paper, three dimensional (3D) analytical model for subthreshold characteristics of doped FinFET has been presented. The separation of variables technique is used to solve the 3D Poisson's equation analytically with appropriate boundary conditions so as to obtain the expression for channel potential. The thus obtained potential distribution function has been employed in deriving subthreshold current and subthreshold slope model. The channel potential characteristics have been studied as a function of various device parameters such as gate length, gate oxide thickness and channel doping. The proposed analytical model results have been validated by comparing with the simulation data obtained by the 3D device simulator ATLAS™ from Silvaco.
A Semi-Implicit, Three-Dimensional Model for Estuarine Circulation
Smith, Peter E.
2006-01-01
A semi-implicit, finite-difference method for the numerical solution of the three-dimensional equations for circulation in estuaries is presented and tested. The method uses a three-time-level, leapfrog-trapezoidal scheme that is essentially second-order accurate in the spatial and temporal numerical approximations. The three-time-level scheme is shown to be preferred over a two-time-level scheme, especially for problems with strong nonlinearities. The stability of the semi-implicit scheme is free from any time-step limitation related to the terms describing vertical diffusion and the propagation of the surface gravity waves. The scheme does not rely on any form of vertical/horizontal mode-splitting to treat the vertical diffusion implicitly. At each time step, the numerical method uses a double-sweep method to transform a large number of small tridiagonal equation systems and then uses the preconditioned conjugate-gradient method to solve a single, large, five-diagonal equation system for the water surface elevation. The governing equations for the multi-level scheme are prepared in a conservative form by integrating them over the height of each horizontal layer. The layer-integrated volumetric transports replace velocities as the dependent variables so that the depth-integrated continuity equation that is used in the solution for the water surface elevation is linear. Volumetric transports are computed explicitly from the momentum equations. The resulting method is mass conservative, efficient, and numerically accurate.
International Nuclear Information System (INIS)
Kamaya, Masayuki; Kitamura, Takayuki
2006-01-01
In order to understand the initiation behavior of microstructurally small cracks in a stress corrosion cracking condition, it is important to know the tensile normal stress acting on the grain boundary (normal G.B. stress). The local stress in a polycrystalline body is greatly influenced by deformation constraint which is caused by anisotropic and/or inhomogeneous property of each grain. In present study, the local normal G.B. stress on bi- and tri-crystal bodies and a three-dimensional polycrystalline body consisting of 100 grains were evaluated by the finite element method under a remote uniform tensile stress condition. The polycrystalline body was generated by using a Monte Carlo procedure and random orientations were assigned to each grain. It was revealed that the local normal G.B. stress on the polycrystalline body is inhomogeneous under uniform applied stress. The stress tends to be large near the triple points due to the deformation constraint caused by adjacent grains, even though the grain boundary inclination to the load axis has large influence. It was also shown that particular high stress was not observed at corners of the polycrystalline body. (author)
Hsieh, Paul A.; Winston, Richard B.
2002-01-01
Model Viewer is a computer program that displays the results of three-dimensional groundwater models. Scalar data (such as hydraulic head or solute concentration) may be displayed as a solid or a set of isosurfaces, using a red-to-blue color spectrum to represent a range of scalar values. Vector data (such as velocity or specific discharge) are represented by lines oriented to the vector direction and scaled to the vector magnitude. Model Viewer can also display pathlines, cells or nodes that represent model features such as streams and wells, and auxiliary graphic objects such as grid lines and coordinate axes. Users may crop the model grid in different orientations to examine the interior structure of the data. For transient simulations, Model Viewer can animate the time evolution of the simulated quantities. The current version (1.0) of Model Viewer runs on Microsoft Windows 95, 98, NT and 2000 operating systems, and supports the following models: MODFLOW-2000, MODFLOW-2000 with the Ground-Water Transport Process, MODFLOW-96, MOC3D (Version 3.5), MODPATH, MT3DMS, and SUTRA (Version 2D3D.1). Model Viewer is designed to directly read input and output files from these models, thus minimizing the need for additional postprocessing. This report provides an overview of Model Viewer. Complete instructions on how to use the software are provided in the on-line help pages.
John F. Hunt; Margit. Tamasy-Bano; Heike. Nyist
1999-01-01
A three-dimensional structural panel, called FPL Spaceboard, was developed at the USDA Forest Products Laboratory. Spaceboard panels have been formed using a variety of fibrous materials using either a wet- or dry-forming process. Geometrically, the panel departs from the traditional two-dimensional flat panel by integrally forming an array of perpendicular ribs and...
Directory of Open Access Journals (Sweden)
Jean-Paul Kone
2017-03-01
Full Text Available A review of published three-dimensional, computational fluid dynamics models for proton exchange membrane fuel cells that accounts for multiphase flow is presented. The models can be categorized as models for transport phenomena, geometry or operating condition effects, and thermal effects. The influences of heat and water management on the fuel cell performance have been repeatedly addressed, and these still remain two central issues in proton exchange membrane fuel cell technology. The strengths and weaknesses of the models, the modelling assumptions, and the model validation are discussed. The salient numerical features of the models are examined, and an overview of the most commonly used computational fluid dynamic codes for the numerical modelling of proton exchange membrane fuel cells is given. Comprehensive three-dimensional multiphase flow computational fluid dynamic models accounting for the major transport phenomena inside a complete cell have been developed. However, it has been noted that more research is required to develop models that include among other things, the detailed composition and structure of the catalyst layers, the effects of water droplets movement in the gas flow channels, the consideration of phase change in both the anode and the cathode sides of the fuel cell, and dissolved water transport.
Energy Technology Data Exchange (ETDEWEB)
Hu, Rui
2017-09-03
Mixing, thermal-stratification, and mass transport phenomena in large pools or enclosures play major roles for the safety of reactor systems. Depending on the fidelity requirement and computational resources, various modeling methods, from the 0-D perfect mixing model to 3-D Computational Fluid Dynamics (CFD) models, are available. Each is associated with its own advantages and shortcomings. It is very desirable to develop an advanced and efficient thermal mixing and stratification modeling capability embedded in a modern system analysis code to improve the accuracy of reactor safety analyses and to reduce modeling uncertainties. An advanced system analysis tool, SAM, is being developed at Argonne National Laboratory for advanced non-LWR reactor safety analysis. While SAM is being developed as a system-level modeling and simulation tool, a reduced-order three-dimensional module is under development to model the multi-dimensional flow and thermal mixing and stratification in large enclosures of reactor systems. This paper provides an overview of the three-dimensional finite element flow model in SAM, including the governing equations, stabilization scheme, and solution methods. Additionally, several verification and validation tests are presented, including lid-driven cavity flow, natural convection inside a cavity, laminar flow in a channel of parallel plates. Based on the comparisons with the analytical solutions and experimental results, it is demonstrated that the developed 3-D fluid model can perform very well for a wide range of flow problems.
Energy Technology Data Exchange (ETDEWEB)
Suh, Kyung Suk; Park, Ki Hyun; Min, Byung Il; Kim, Sora; Yang, Byung Mo [Nuclear Environmental Safety Research Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2016-05-15
It is necessary to consider the overall countermeasure for analysis of nuclear activities according to the increase of the nuclear facilities like nuclear power and reprocessing plants in the neighboring countries including China, Taiwan, North Korea, Japan and South Korea. South Korea and comprehensive nuclear-test-ban treaty organization (CTBTO) are now operating the monitoring instruments to detect radionuclides released into the air. It is important to estimate the origin of radionuclides measured using the detection technology as well as the monitoring analysis in aspects of investigation and security of the nuclear activities in neighboring countries. A three-dimensional forward/backward trajectory model has been developed to estimate the origin of radionuclides for a covert nuclear activity. The developed trajectory model was composed of forward and backward modules to track the particle positions using finite difference method. A three-dimensional trajectory model was validated using the measured data at Chernobyl accident. The calculated results showed a good agreement by using the high concentration measurements and the locations where was near a release point. The three-dimensional trajectory model had some uncertainty according to the release time, release height and time interval of the trajectory at each release points. An atmospheric dispersion model called long-range accident dose assessment system (LADAS), based on the fields of regards (FOR) technique, was applied to reduce the uncertainties of the trajectory model and to improve the detective technology for estimating the radioisotopes emission area. The detective technology developed in this study can evaluate in release area and origin for covert nuclear activities based on measured radioisotopes at monitoring stations, and it might play critical tool to improve the ability of the nuclear safety field.
International Nuclear Information System (INIS)
Suh, Kyung Suk; Park, Ki Hyun; Min, Byung Il; Kim, Sora; Yang, Byung Mo
2016-01-01
It is necessary to consider the overall countermeasure for analysis of nuclear activities according to the increase of the nuclear facilities like nuclear power and reprocessing plants in the neighboring countries including China, Taiwan, North Korea, Japan and South Korea. South Korea and comprehensive nuclear-test-ban treaty organization (CTBTO) are now operating the monitoring instruments to detect radionuclides released into the air. It is important to estimate the origin of radionuclides measured using the detection technology as well as the monitoring analysis in aspects of investigation and security of the nuclear activities in neighboring countries. A three-dimensional forward/backward trajectory model has been developed to estimate the origin of radionuclides for a covert nuclear activity. The developed trajectory model was composed of forward and backward modules to track the particle positions using finite difference method. A three-dimensional trajectory model was validated using the measured data at Chernobyl accident. The calculated results showed a good agreement by using the high concentration measurements and the locations where was near a release point. The three-dimensional trajectory model had some uncertainty according to the release time, release height and time interval of the trajectory at each release points. An atmospheric dispersion model called long-range accident dose assessment system (LADAS), based on the fields of regards (FOR) technique, was applied to reduce the uncertainties of the trajectory model and to improve the detective technology for estimating the radioisotopes emission area. The detective technology developed in this study can evaluate in release area and origin for covert nuclear activities based on measured radioisotopes at monitoring stations, and it might play critical tool to improve the ability of the nuclear safety field
Susilo, Monica E; Roeder, Blayne A; Voytik-Harbin, Sherry L; Kokini, Klod; Nauman, Eric A
2010-04-01
The three-dimensional microstructure and mechanical properties of the collagen fibrils within the extracellular matrix (ECM) is now being recognized as a primary factor in regulating cell proliferation and differentiation. Therefore, an appreciation of the mechanical aspects by which a cell interacts with its ECM is required for the development of engineered tissues. Ultimately, using these interactions to design tissue equivalents requires mathematical models with three-dimensional architecture. In this study, a three-dimensional model of a collagen fibril matrix undergoing uniaxial tensile stress was developed by making use of cellular solids. A structure consisting of thin struts was chosen to represent the arrangement of collagen fibrils within an engineered ECM. To account for the large deformation of tissues, the collagen fibrils were modeled as hyperelastic neo-Hookean or Mooney-Rivlin materials. The use of cellular solids allowed the fibril properties to be related to the ECM properties in closed form, which, in turn, allowed the estimation of fibril properties using ECM experimental data. A set of previously obtained experimental data consisting of simultaneous measures of the fibril microstructure and mechanical tests was used to evaluate the model's capability to estimate collagen fibril mechanical property when given tissue-scale data and to predict the tissue-scale mechanical properties when given estimated fibril stiffness. The fibril tangent modulus was found to be 1.26 + or - 0.70 and 1.62 + or - 0.88 MPa when the fibril was modeled as neo-Hookean and Mooney-Rivlin material, respectively. There was no statistical significance of the estimated fibril tangent modulus among the different groups. Sensitivity analysis showed that the fibril mechanical properties and volume fraction were the two input parameters which required accurate values. While the volume fraction was easily obtained from the initial image of the gel, the fibril mechanical properties
Design of a three-dimensional site-scale model for the unsaturated zone at Yucca Mountain, Nevada
International Nuclear Information System (INIS)
Wittwer, C.S.; Bodvarsson, G.S.; Chornack, M.P.; Flint, A.L.; Lewis, B.D.; Spengler, R.W.; Flint, L.E.; Rautman, C.A.
1992-01-01
A three-dimensional model of moisture flow within the unsaturated zone at Yucca Mountain is being developed. This site-scale model covers an area of about 30 km 2 and is bounded by major faults to the east and west. A detailed numerical grid has been developed based on location of boreholes, different infiltration zones, hydrogeological units and their outcrops, major faults, and water level data. Different maps, such as contour maps and isopachs maps, are presented for the different infiltration zones, and for the base of the Tiva Canyon, the Paintbrush, and the Topopah Spring hydrogeological units
International Nuclear Information System (INIS)
Zhang, Jinping; Chen, Yuping; Hu, Mengning; Chen, Xianfeng
2015-01-01
In this paper, an improved three-dimensional two-temperature model for multi-pulse femtosecond laser ablation of aluminum was proposed and proved in our experiment. Aiming to achieve hole-drilling with a high ratio of depth/entrance diameter in vacuum, this model can predict the depth and radius of the drilled holes precisely when employing different laser parameters. Additionally, for multi-pulse laser ablation, we found that the laser fluence and number of pulses are the dominant parameters and the multi-pulse ablation threshold is much lower than the single-pulse one, which will help to obtain high-quality holes
Energy Technology Data Exchange (ETDEWEB)
Zhang, Jinping; Chen, Yuping, E-mail: ypchen@sjtu.edu.cn; Hu, Mengning; Chen, Xianfeng [State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China)
2015-02-14
In this paper, an improved three-dimensional two-temperature model for multi-pulse femtosecond laser ablation of aluminum was proposed and proved in our experiment. Aiming to achieve hole-drilling with a high ratio of depth/entrance diameter in vacuum, this model can predict the depth and radius of the drilled holes precisely when employing different laser parameters. Additionally, for multi-pulse laser ablation, we found that the laser fluence and number of pulses are the dominant parameters and the multi-pulse ablation threshold is much lower than the single-pulse one, which will help to obtain high-quality holes.
International Nuclear Information System (INIS)
Collins, R.; Perez-Martin, A.M.C.; Dominguez-Vazquez, J.; Jimenez-Rodriguez, J.J.
1994-01-01
A simple model for three-dimensional material relaxation associated with atomic mixing is presented. The relaxation of the solid to accommodate the extra effective displacement volume Ω of an implanted or relocated atom is modelled by treating the surrounding solid as an incompressible medium. This leads to a tractable general formalism which can be used to predict implant distribution and changes in surface topography induced by ion beams, both in monatomic and multicomponent targets. The two-component case is discussed in detail. (orig.)
Lazarowitz, Reuven; Naim, Raphael
2014-01-01
The cell topic was taught to 9th-grade students in three modes of instruction: (a) students "hands-on," who constructed three-dimensional cell organelles and macromolecules during the learning process; (b) teacher demonstration of the three-dimensional model of the cell structures; and (c) teaching the cell topic with the regular…
Gong, Zhenyu; Li, Guohua; Liu, Yanpu; He, Lisheng; Zhou, Bing; Li, Dichen
2012-01-01
To evaluate the feasibility and effectiveness of reconstruction of mandibular bone defects using three-dimensional skull model and individualized titanium prosthetics from computer assisted design. Between July 2002 and November 2009, 9 patients with mandibular defects accepted restorative operation using individualized bone prosthetics. Among 9 cases, 4 were male and 5 were female, aged 19-55 years. The causes of mandibulectomy were benign lesions in 8 patients and carcinoma of gingival in 1 patient. Mandibular defects exceeded midline in 2 cases, involved condylar in 4 cases, and was limited in one side without involvement of temporo-mandibular joint in 3 cases. The range of bone defects was 9.0 cm x 2.5 cm-17.0 cm x 2.5 cm. The preoperative spiral CT scan was performed and three-dimensional skull model was obtained. Titanium prosthetics of mandibular defects were designed and fabricated through multi-step procedure of reverse engineering and rapid prototyping. Titanium prosthetics were used for one-stage repair of mandibular bone defects, then two-stage implant denture was performed after 6 months. The individualized titanium prosthetics were inserted smoothly with one-stage operative time of 10-23 minutes. All the cases achieved incision healing by first intention and the oblique mandibular movement was corrected. They all got satisfactory face, had satisfactory contour and good occlusion. In two-stage operation, no loosening of the implants was observed and the abutments were in good position with corresponding teeth which were designed ideally before operation. All cases got satisfactory results after 1-9 years of follow-up. At last follow-up, X-ray examinations showed no loosening of implants with symmetry contour. Computer assisted design and three-dimensional skull model techniques could accomplish the design and manufacture of individualized prosthetic for the repair of mandibular bone defects.
Kinetic theory model for the flow of a simple gas from a three-dimensional axisymmetric nozzle
Riley, B. R.
1991-01-01
A system of nonlinear integral equations equivalent to the Krook kinetic equations for the steady state is the mathematical basis used to develop a computer code to model the flowfields for low-thrust three-dimensional axisymmetric nozzles. The method of characteristics is used to solve numerically by an iteration process the approximated Boltzmann equation for the number density, temperature, and velocity profiles of a simple gas as it expands into a vacuum. Results predict backscatter and show the effect of the nozzle wall boundary layer on the external flowfields.
Directory of Open Access Journals (Sweden)
Soo Y. Kim
2015-01-01
Full Text Available Supraspinatus tendon tears are common and lead to changes in the muscle architecture. To date, these changes have not been investigated for the distinct regions and parts of the pathologic supraspinatus. The purpose of this study was to create a novel three-dimensional (3D model of the muscle architecture throughout the supraspinatus and to compare the architecture between muscle regions and parts in relation to tear severity. Twelve cadaveric specimens with varying degrees of tendon tears were used. Three-dimensional coordinates of fiber bundles were collected in situ using serial dissection and digitization. Data were reconstructed and modeled in 3D using Maya. Fiber bundle length (FBL and pennation angle (PA were computed and analyzed. FBL was significantly shorter in specimens with large retracted tears compared to smaller tears, with the deeper fibers being significantly shorter than other parts in the anterior region. PA was significantly greater in specimens with large retracted tears, with the superficial fibers often demonstrating the largest PA. The posterior region was absent in two specimens with extensive tears. Architectural changes associated with tendon tears affect the regions and varying depths of supraspinatus differently. The results provide important insights on residual function of the pathologic muscle, and the 3D model includes detailed data that can be used in future modeling studies.
Directory of Open Access Journals (Sweden)
Arunachalam Sangeetha
2012-01-01
Full Text Available Context: To understand the effect of masticatory and parafunctional forces on the integrity of the prosthesis and the underlying cement layer. Aims: The purpose of this study was to evaluate the stress pattern in the cement layer and the fixed prosthesis, on subjecting a three-dimensional finite element model to simulated occlusal loading. Materials and Methods: Three-dimensional finite element model was simulated to replace missing mandibular first molar with second premolar and second molar as abutments. The model was subjected to a range of occlusal loads (20, 30, 40 MPa in two different directions - vertical and 30° to the vertical. The cements (zinc phosphate, polycarboxylate, glass ionomer, and composite were modeled with two cement thicknesses - 25 and 100 μm. Stresses were determined in certain reference points in fixed prosthesis and the cement layer. Statistical Analysis Used: The stress values are mathematic calculations without variance; hence, statistical analysis is not routinely required. Results: Stress levels were calculated according to Von Mises criteria for each node. Maximum stresses were recorded at the occlusal surface, axio-gingival corners, followed by axial wall. The stresses were greater with lateral load and with 100-μm cement thickness. Results revealed higher stresses for zinc phosphate cement, followed by composites. Conclusions: The thinner cement interfaces favor the success of the prosthesis. The stresses in the prosthesis suggest rounding of axio-gingival corners and a well-established finish line as important factors in maintaining the integrity of the prosthesis.
Lu, Dongliang; Li, Keqiang; Liang, Shengkang; Lin, Guohong; Wang, Xiulin
2017-01-15
With anthropogenic changes, the structure and quantity of nitrogen nutrients have changed in coastal ocean, which has dramatically influenced the water quality. Water quality modeling can contribute to the necessary scientific grounding of coastal management. In this paper, some of the dynamic functions and parameters of nitrogen were calibrated based on coastal field experiments covering the dynamic nitrogen processes in Jiaozhou Bay (JZB), including phytoplankton growth, respiration, and mortality; particulate nitrogen degradation; and dissolved organic nitrogen remineralization. The results of the field experiments and box model simulations showed good agreement (RSD=20%±2% and SI=0.77±0.04). A three-dimensional water quality model of nitrogen (3DWQMN) in JZB was improved and the dynamic parameters were updated according to field experiments. The 3DWQMN was validated based on observed data from 2012 to 2013, with good agreement (RSD=27±4%, SI=0.68±0.06, and K=0.48±0.04), which testifies to the model's credibility. Copyright © 2016 Elsevier Ltd. All rights reserved.
Geometric Model of a Coronal Cavity
Kucera, Therese A.; Gibson, S. E.; Ratawicki, D.; Dove, J.; deToma, G.; Hao, J.; Hudson, H. S.; Marque, C.; McIntosh, P. S.; Reeves, K. K.;
2010-01-01
We observed a coronal cavity from August 8-18 2007 during a multi-instrument observing campaign organized under the auspices of the International Heliophysical Year (IHY). Here we present initial efforts to model the cavity with a geometrical streamer-cavity model. The model is based the white-light streamer mode] of Gibson et a]. (2003 ), which has been enhanced by the addition of a cavity and the capability to model EUV and X-ray emission. The cavity is modeled with an elliptical cross-section and Gaussian fall-off in length and width inside the streamer. Density and temperature can be varied in the streamer and cavity and constrained via comparison with data. Although this model is purely morphological, it allows for three-dimensional, multi-temperature analysis and characterization of the data, which can then provide constraints for future physical modeling. Initial comparisons to STEREO/EUVI images of the cavity and streamer show that the model can provide a good fit to the data. This work is part of the effort of the International Space Science Institute International Team on Prominence Cavities
A GRID OF THREE-DIMENSIONAL STELLAR ATMOSPHERE MODELS OF SOLAR METALLICITY. I. GENERAL PROPERTIES, GRANULATION, AND ATMOSPHERIC EXPANSION
International Nuclear Information System (INIS)
Trampedach, Regner; Asplund, Martin; Collet, Remo; Nordlund, Åke; Stein, Robert F.
2013-01-01
Present grids of stellar atmosphere models are the workhorses in interpreting stellar observations and determining their fundamental parameters. These models rely on greatly simplified models of convection, however, lending less predictive power to such models of late-type stars. We present a grid of improved and more reliable stellar atmosphere models of late-type stars, based on deep, three-dimensional (3D), convective, stellar atmosphere simulations. This grid is to be used in general for interpreting observations and improving stellar and asteroseismic modeling. We solve the Navier Stokes equations in 3D and concurrent with the radiative transfer equation, for a range of atmospheric parameters, covering most of stellar evolution with convection at the surface. We emphasize the use of the best available atomic physics for quantitative predictions and comparisons with observations. We present granulation size, convective expansion of the acoustic cavity, and asymptotic adiabat as functions of atmospheric parameters.
Moon, S.; Perron, J. T.; Martel, S. J.; Holbrook, W. S.; St. Clair, J.
2017-04-01
Bedrock fractures influence the rates of surface processes that drive landscape evolution and are in turn influenced by landforms that perturb ambient tectonic and gravitational stress fields. In this modeling study, we examine how three-dimensional topography and tectonic stress regimes influence elastic stress fields and bedrock fracture patterns beneath Earth's surface. We illustrate general effects of landform orientation and of tectonic stress magnitude and anisotropy using boundary element models of stresses beneath synthetic elongated ridges with different aspect ratios. We then examine the more detailed effects of landform shape using natural landscapes in Colorado and South Carolina. We show that the stress field is most sensitive to topographic perturbations if the most compressive horizontal tectonic stress is oriented perpendicular to the long axis of elongated landforms such as ridges and valleys and that topographic stress perturbations are most pronounced beneath landforms with higher mean curvatures, such as channel junctions and ridge crests. The shape of a predicted fracture-rich zone in the subsurface depends mainly on the orientation of landforms relative to the most compressive horizontal tectonic stress direction and a dimensionless ratio that expresses the relative magnitudes of topographic stresses associated with horizontal tectonic compression and topographic relief. Variations in this dimensionless ratio can also change the predicted orientations of potential opening-mode fracture planes. We use these model results to illustrate how topographic perturbations of three-dimensional tectonic and gravitational stresses could influence landscape evolution by altering the rates and spatial heterogeneity of surface processes and groundwater flow.
Olszewski, R; Tranduy, K; Reychler, H
2010-07-01
The authors present a new procedure of computer-assisted genioplasty. They determined the anterior, posterior and inferior limits of the chin in relation to the skull and face with the newly developed and validated three-dimensional cephalometric planar analysis (ACRO 3D). Virtual planning of the osteotomy lines was carried out with Mimics (Materialize) software. The authors built a three-dimensional rapid-prototyping multi-position model of the chin area from a medical low-dose CT scan. The transfer of virtual information to the operating room consisted of two elements. First, the titanium plates on the 3D RP model were pre-bent. Second, a surgical guide for the transfer of the osteotomy lines and the positions of the screws to the operating room was manufactured. The authors present the first case of the use of this model on a patient. The postoperative results are promising, and the technique is fast and easy-to-use. More patients are needed for a definitive clinical validation of this procedure. Copyright 2010 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Campbell, C. L.; Wood, K.; Brown, C. T. A.; Moseley, H.
2016-07-01
We explore the effects of three dimensional (3D) tumour structures on depth dependent fluence rates, photodynamic doses (PDD) and fluorescence images through Monte Carlo radiation transfer modelling of photodynamic therapy. The aim with this work was to compare the commonly used uniform tumour densities with non-uniform densities to determine the importance of including 3D models in theoretical investigations. It was found that fractal 3D models resulted in deeper penetration on average of therapeutic radiation and higher PDD. An increase in effective treatment depth of 1 mm was observed for one of the investigated fractal structures, when comparing to the equivalent smooth model. Wide field fluorescence images were simulated, revealing information about the relationship between tumour structure and the appearance of the fluorescence intensity. Our models indicate that the 3D tumour structure strongly affects the spatial distribution of therapeutic light, the PDD and the wide field appearance of surface fluorescence images.
International Nuclear Information System (INIS)
Dudek, M.A.; Hunter, L.; Kranz, S.; Williams, J.J.; Lau, S.H.; Chawla, N.
2010-01-01
The volume, size, and dispersion of porosity in solder joints are known to affect mechanical performance and reliability. Most of the techniques used to characterize the three-dimensional (3D) nature of these defects are destructive. With the enhancements in high resolution computed tomography (CT), the detection limits of intrinsic microstructures have been significantly improved. Furthermore, the 3D microstructure of the material can be used in finite element models to understand their effect on microscopic deformation. In this paper we describe a technique utilizing high resolution (< 1 μm) X-ray tomography for the three-dimensional (3D) visualization of pores in Sn-3.9Ag-0.7Cu/Cu joints. The characteristics of reflow porosity, including volume fraction and distribution, were investigated for two reflow profiles. The size and distribution of porosity size were visualized in 3D for four different solder joints. In addition, the 3D virtual microstructure was incorporated into a finite element model to quantify the effect of voids on the lap shear behavior of a solder joint. The presence, size, and location of voids significantly increased the severity of strain localization at the solder/copper interface.
Cheng, Wen-Nuan Kara; Hardy, Lew; Woodman, Tim
2011-02-01
We tested the predictive validity of the recently validated three-dimensional model of performance anxiety (Chang, Hardy, & Markland, 2009) with elite tae-kwon-do competitors (N = 99). This conceptual framework emphasized the adaptive potential of anxiety by including a regulatory dimension (reflected by perceived control) along with the intensity-oriented dimensions of cognitive and physiological anxiety. Anxiety was assessed 30 min before a competitive contest using the Three-Factor Anxiety Inventory. Competitors rated their performance on a tae-kwon-do-specific performance scale within 30 min after completion of their contest. Moderated hierarchical regression analyses revealed initial support for the predictive validity of the three-dimensional performance anxiety model. The regulatory dimension of anxiety (perceived control) revealed significant main and interactive effects on performance. This dimension appeared to be adaptive, as performance was better under high than low perceived control, and best vs. worst performance was associated with highest vs. lowest perceived control, respectively. Results are discussed in terms of the importance of the regulatory dimension of anxiety.
Huang, M.; Bisht, G.; Zhou, T.; Chen, X.; Dai, H.; Hammond, G. E.; Riley, W. J.; Downs, J.; Liu, Y.; Zachara, J. M.
2016-12-01
A fully coupled three-dimensional surface and subsurface land model is developed and applied to a site along the Columbia River to simulate three-way interactions among river water, groundwater, and land surface processes. The model features the coupling of the Community Land Model version 4.5 (CLM4.5) and a massively-parallel multi-physics reactive tranport model (PFLOTRAN). The coupled model (CLM-PFLOTRAN) is applied to a 400m×400m study domain instrumented with groundwater monitoring wells in the Hanford 300 Area along the Columbia River. CLM-PFLOTRAN simulations are performed at three different spatial resolutions over the period 2011-2015 to evaluate the impact of spatial resolution on simulated variables. To demonstrate the difference in model simulations with and without lateral subsurface flow, a vertical-only CLM-PFLOTRAN simulation is also conducted for comparison. Results show that the coupled model is skillful in simulating stream-aquifer interactions, and the land-surface energy partitioning can be strongly modulated by groundwater-river water interactions in high water years due to increased soil moisture availability caused by elevated groundwater table. In addition, spatial resolution does not seem to impact the land surface energy flux simulations, although it is a key factor for accurately estimating the mass exchange rates at the boundaries and associated biogeochemical reactions in the aquifer. The coupled model developed in this study establishes a solid foundation for understanding co-evolution of hydrology and biogeochemistry along the river corridors under historical and future hydro-climate changes.
Energy Technology Data Exchange (ETDEWEB)
Noguchi, K.; Endo, M. [Waseda University, Tokyo (Japan). School of Science and Engineering
1997-10-22
Study is made on the theory of three-dimensional modelling of TDEM (Time Domain Electromagnetic) method based on the theory of Wang and Hohmann. A difference scheme is built and investigation is conducted about calculation accuracy with attention paid especially to space and time division, and the obtained optimum value is compared with the analytical solution for a homogeneous medium. As the result, it becomes possible to have a high-accuracy TDEM response thanks to the obtained optimum parameter. In an example, a response is determined in the case of a high-resistivity body in presence near the ground surface. Calculation is performed under the given conditions of a medium 100 ohm/m in resistivity, anomalous bodies 200, 500, 1000, 2000,5000, and 10,000 ohm/m in resistivity, respectively, and a distance in the direction of depth of 20m. The result indicates that it is possible to estimate the effect of the ground surface terrain on a TDEM response. Since the effect of the ground surface terrain emerges at the initial part of a response, it is inferred that consideration of terrain is mandatory in building a model if it is for interpreting the subsurface structure in detail. 5 refs., 7 figs.
Ferrage, Eric; Hubert, Fabien; Tertre, Emmanuel; Delville, Alfred; Michot, Laurent J.; Levitz, Pierre
2015-06-01
Swelling clay minerals play a key role in the control of water and pollutant migration in natural media such as soils. Moreover, swelling clay particles' orientational properties in porous media have significant implications for the directional dependence of fluid transfer. Herein we investigate the ability to mimic the organization of particles in natural swelling-clay porous media using a three-dimensional sequential particle deposition procedure [D. Coelho, J.-F. Thovert, and P. M. Adler, Phys. Rev. E 55, 1959 (1997), 10.1103/PhysRevE.55.1959]. The algorithm considered is first used to simulate disk packings. Porosities of disk packings fall onto a single master curve when plotted against the orientational scalar order parameter value. This relation is used to validate the algorithm used in comparison with existing ones. The ellipticity degree of the particles is shown to have a negligible effect on the packing porosity for ratios ℓa/ℓb less than 1.5, whereas a significant increase in porosity is obtained for higher values. The effect of the distribution of the geometrical parameters (size, aspect ratio, and ellipticity degree) of particles on the final packing properties is also investigated. Finally, the algorithm is used to simulate particle packings for three size fractions of natural swelling-clay mineral powders. Calculated data regarding the distribution of the geometrical parameters and orientation of particles in porous media are successfully compared with experimental data obtained for the same samples. The results indicate that the obtained virtual porous media can be considered representative of natural samples and can be used to extract properties difficult to obtain experimentally, such as the anisotropic features of pore and solid phases in a system.
Ferrage, Eric; Hubert, Fabien; Tertre, Emmanuel; Delville, Alfred; Michot, Laurent J; Levitz, Pierre
2015-06-01
Swelling clay minerals play a key role in the control of water and pollutant migration in natural media such as soils. Moreover, swelling clay particles' orientational properties in porous media have significant implications for the directional dependence of fluid transfer. Herein we investigate the ability to mimic the organization of particles in natural swelling-clay porous media using a three-dimensional sequential particle deposition procedure [D. Coelho, J.-F. Thovert, and P. M. Adler, Phys. Rev. E 55, 1959 (1997)]. The algorithm considered is first used to simulate disk packings. Porosities of disk packings fall onto a single master curve when plotted against the orientational scalar order parameter value. This relation is used to validate the algorithm used in comparison with existing ones. The ellipticity degree of the particles is shown to have a negligible effect on the packing porosity for ratios ℓ(a)/ℓ(b) less than 1.5, whereas a significant increase in porosity is obtained for higher values. The effect of the distribution of the geometrical parameters (size, aspect ratio, and ellipticity degree) of particles on the final packing properties is also investigated. Finally, the algorithm is used to simulate particle packings for three size fractions of natural swelling-clay mineral powders. Calculated data regarding the distribution of the geometrical parameters and orientation of particles in porous media are successfully compared with experimental data obtained for the same samples. The results indicate that the obtained virtual porous media can be considered representative of natural samples and can be used to extract properties difficult to obtain experimentally, such as the anisotropic features of pore and solid phases in a system.
Three-dimensional reactor model for the Paks NPP full-scope simulator
International Nuclear Information System (INIS)
Gyori, C.; Hegyi, G.; Hozer, Z.; Kereszturi, A.; Maraczy, C.
1993-01-01
The reactor model includes thermohydraulic and neutron-physical components. The thermohydraulic model is based on the SMABRE code developed at the Technical Research Centre of Finland for the analysis of loss-of-coolant transients in PWRs. The fuel rod model will be replaced by a new software module providing a comprehensive description of the behavior of fuel rods during reactor transients and hypothetical accidents. The calculation is performed in four individual models: fuel rod temperature model, fuel rod internal pressure model, fuel rod deformation model and fuel rod failure model. In the neutron-physical model the core is calculated with nodes for all of the 349 fuel assemblies, and each assembly is calculated in ten layers. (Z.S.) 1 fig., 5 refs
Savitri, I. T.; Badri, C.; Sulistyani, L. D.
2017-08-01
Presurgical treatment planning plays an important role in the reconstruction and correction of defects in the craniomaxillofacial region. The advance of solid freeform fabrication techniques has significantly improved the process of preparing a biomodel using computer-aided design and data from medical imaging. Many factors are implicated in the accuracy of the 3D model. To determine the accuracy of three-dimensional fused deposition modeling (FDM) models compared with three-dimensional CT scans in the measurement of the mandibular ramus vertical length, gonion-menton length, and gonial angle. Eight 3D models were produced from the CT scan data (DICOM file) of eight patients at the Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, University of Indonesia, Cipto Mangunkusumo Hospital. Three measurements were done three times by two examiners. The measurements of the 3D CT scans were made using OsiriX software, while the measurements of the 3D models were made using a digital caliper and goniometry. The measurement results were then compared. There is no significant difference between the measurements of the mandibular ramus vertical length, gonion-menton length, and gonial angle using 3D CT scans and FDM 3D models. FDM 3D models are considered accurate and are acceptable for clinical applications in dental and craniomaxillofacial surgery.
DEFF Research Database (Denmark)
Shaikh, Danish; Kjær Schmidt, Michael
2017-01-01
Three-dimensional acoustic localisation is relevant in personal and social robot platforms. Conventional approaches extract interaural time difference cues via impractically large stationary two-dimensional multi-microphone grids with at least four microphones or spectral cues via head-related tr......Three-dimensional acoustic localisation is relevant in personal and social robot platforms. Conventional approaches extract interaural time difference cues via impractically large stationary two-dimensional multi-microphone grids with at least four microphones or spectral cues via head......-related transfer functions of stationary KEMAR dummy heads equipped with two microphones. We present a preliminary approach using two sound sensors, whose directed movements resolve the location of a stationary acoustic target in three dimensions. A model of the peripheral auditory system of lizards provides sound...... direction information in a single plane which by itself is insufficient to localise the acoustic target in three dimensions. Two spatial orientations of this plane by rotating the sound sensors by -45 deg. and +45 deg. along the sagittal axis generate a pair of measurements, each encoding the location...
International Nuclear Information System (INIS)
Meloni, S.
1998-01-01
To simulate transmitted radiation in agroforestry systems, radiative transfer models usually require a detailed three-dimensional description of the tree canopy. We propose here a simplification of the description of the three-dimensional structure of wild cherry trees (Prunus avium). The simplified tree description was tested against the detailed one for five-year-old wild cherry. It allowed accurate simulation of transmitted radiation and avoided tedious measurements of tree structure. The simplified description was then applied to older trees. Allometric relationships were used to compute the parameters not available on free-grown trees. The transmitted radiation in an agroforestry system was simulated at four different ages: 5, 10, 15 and 20 years. The trees were planted on a 5 m square grid. Two row orientations, chosen to provide different transmitted radiation patterns, were tested: north/south and north- east/south-west. The simulations showed that the daily mean transmitted radiation was reduced from 92% of incident radiation under five-year-old trees to 37% under 20-year-old trees. The variability of transmitted radiation increased with tree growth. The row orientation had only small effects on the shaded area at the beginning and end of the day when solar elevation was low. (author)
Directory of Open Access Journals (Sweden)
Ada J Klinkhamer
Full Text Available Digital dissection is a relatively new technique that has enabled scientists to gain a better understanding of vertebrate anatomy. It can be used to rapidly disseminate detailed, three-dimensional information in an easily accessible manner that reduces the need for destructive, traditional dissections. Here we present the results of a digital dissection on the appendicular musculature of the Australian estuarine crocodile (Crocodylus porosus. A better understanding of this until now poorly known system in C. porosus is important, not only because it will expand research into crocodilian locomotion, but because of its potential to inform muscle reconstructions in dinosaur taxa. Muscles of the forelimb and hindlimb are described and three-dimensional interactive models are included based on CT and MRI scans as well as fresh-tissue dissections. Differences in the arrangement of musculature between C. porosus and other groups within the Crocodylia were found. In the forelimb, differences are restricted to a single tendon of origin for triceps longus medialis. For the hindlimb, a reduction in the number of heads of ambiens was noted as well as changes to the location of origin and insertion for iliofibularis and gastrocnemius externus.
International Nuclear Information System (INIS)
Hall, M.L.; Davis, A.B.
2005-01-01
Accurate modeling of radiative energy transport through cloudy atmospheres is necessary for both climate modeling with GCMs (Global Climate Models) and remote sensing. Previous modeling efforts have taken advantage of extreme aspect ratios (cells that are very wide horizontally) by assuming a 1-D treatment vertically - the Independent Column Approximation (ICA). Recent attempts to resolve radiation transport through the clouds have drastically changed the aspect ratios of the cells, moving them closer to unity, such that the ICA model is no longer valid. We aim to provide a higher-fidelity atmospheric radiation transport model which increases accuracy while maintaining efficiency. To that end, this paper describes the development of an efficient 3-D-capable radiation code that can be easily integrated into cloud resolving models as an alternative to the resident 1-D model. Applications to test cases from the Intercomparison of 3-D Radiation Codes (I3RC) protocol are shown
Three-Dimensional Subsurface Flow, Fate and Transport of Microbes and Chemicals (3DFATMIC) Model
This model simulates subsurface flow, fate and transport of contaminants that are undergoing chemical or biological transformations. The model is applicable to transient conditions in both saturated and unsaturated zones.
A Monte Carlo reflectance model for soil surfaces with three-dimensional structure
Cooper, K. D.; Smith, J. A.
1985-01-01
A Monte Carlo soil reflectance model has been developed to study the effect of macroscopic surface irregularities larger than the wavelength of incident flux. The model treats incoherent multiple scattering from Lambertian facets distributed on a periodic surface. Resulting bidirectional reflectance distribution functions are non-Lambertian and compare well with experimental trends reported in the literature. Examples showing the coupling of the Monte Carlo soil model to an adding bidirectional canopy of reflectance model are also given.
Three-dimensional combustion modelling of a biomass fired pulverized fuel boiler
Stastny, M.;Ahnert, F.;Spliethoff, H.
2017-01-01
A Computational fluid dynamic (CFD) model was applied for a 200 MW pulverised fuel boiler. Peat, demolition wood and wood residuals were used as fuel. The computer code FLUENT was used for the modelling of the combustion process inside the boiler. The RNG k-epsilon turbulence model together with wall functions was adapted for characterization of the flue gas behaviour. Reaction between fuel and oxidizer was modelled using the mixture-fraction/PDF approach. The CFD calculations were compared w...
Three-dimensional modeling of flow through fractured tuff at Fran Ridge
International Nuclear Information System (INIS)
Eaton, R.R.; Ho, C.K.; Glass, R.J.; Nicholl, M.J.; Arnold, B.W.
1996-01-01
Numerical studies have been made of an infiltration experiment at Fran Ridge using the TOUGH2 code to aid in the selection of computational models for performance assessment. The exercise investigates the capabilities of TOUGH2 to model transient flows through highly fractured tuff and provides a possible means of calibration. Two distinctly different conceptual models were used in the TOUGH2 code, the dual permeability model and the equivalent continuum model. The infiltration test modeled involved the infiltration of dyed ponded water for 36 minutes. The 205 gallon filtration of water observed in the experiment was subsequently modeled using measured Fran Ridge fracture frequencies, and a specified fracture aperture of 285 μm. The dual permeability formulation predicted considerable infiltration along the fracture network, which was in agreement with the experimental observations. As expected, minimal fracture penetration of the infiltrating water was calculated using the equivalent continuum model, thus demonstrating that this model is not appropriate for modeling the highly transient experiment. It is therefore recommended that the dual permeability model be given priority when computing high-flux infiltration for use in performance assessment studies
Three-dimensional modeling of flow through fractured tuff at Fran Ridge
International Nuclear Information System (INIS)
Eaton, R.R.; Ho, C.K.; Glass, RJ.; Nicholl, M.J.; Arnold, B.W.
1996-09-01
Numerical studies have been made of an infiltration experiment at Fran Ridge using the TOUGH2 code to aid in the selection of computational models for performance assessment. The exercise investigates the capabilities of TOUGH2 to model transient flows through highly fractured tuff and provides a possible means of calibration. Two distinctly different conceptual models were used in the TOUGH2 code, the dual permeability model and the equivalent continuum model. The infiltration test modeled involved the infiltration of dyed ponded water for 36 minutes. The 205 gallon infiltration of water observed in the experiment was subsequently modeled using measured Fran Ridge fracture frequencies, and a specified fracture aperture of 285 microm. The dual permeability formulation predicted considerable infiltration along the fracture network, which was in agreement with the experimental observations. As expected, al fracture penetration of the infiltrating water was calculated using the equivalent continuum model, thus demonstrating that this model is not appropriate for modeling the highly transient experiment. It is therefore recommended that the dual permeability model be given priority when computing high-flux infiltration for use in performance assessment studies
A three-dimensional spectral element model for the solution of the hydrostatic primitive equations
International Nuclear Information System (INIS)
Iskandarani, M.; Haidvogel, D.B.; Levin, J.C.
2003-01-01
We present a spectral element model to solve the hydrostatic primitive equations governing large-scale geophysical flows. The highlights of this new model include unstructured grids, dual h-p paths to convergence, and good scalability characteristics on present day parallel computers including Beowulf-class systems. The behavior of the model is assessed on three process-oriented test problems involving wave propagation, gravitational adjustment, and nonlinear flow rectification, respectively. The first of these test problems is a study of the convergence properties of the model when simulating the linear propagation of baroclinic Kelvin waves. The second is an intercomparison of spectral element and finite-difference model solutions to the adjustment of a density front in a straight channel. Finally, the third problem considers the comparison of model results to measurements obtained from a laboratory simulation of flow around a submarine canyon. The aforementioned tests demonstrate the good performance of the model in the idealized/process-oriented limits
Directory of Open Access Journals (Sweden)
Alexandr Kоshev
2014-12-01
Full Text Available The mathematical model of electrochemical processes distribution within the three-dimensional flow-through electrode for the system Fe(III/Fe(II/Fe is described in this paper, considering also the electrochemical reactions of hydrogen and molecular oxygen reduction. Possible dynamic changes in the parameters of electrode, electrolyte and the process are taken into account in the mathematical model, such as electro-conductivity of electrode material, electrolyte flow rate, material porosity and specific electrode surface, concentrations of electro-active substances and other characteristics within the local volume of electrode. Electrode and process characteristics are treated as time and coordinate functions within the electrode volume. The results of calculations and experimental studies of iron electro-reduction are given, the analysis of the numerical modeling is provided.
International Nuclear Information System (INIS)
Chourasia, M.K.; Goswami, T.K.
2007-01-01
A three dimensional model was developed to simulate the transport phenomena in heat and mass generating porous medium cooled under natural convective environment. Unlike the previous works on this aspect, the present model was aimed for bulk stored agricultural produce contained in a permeable package placed on a hard surface. This situation made the bottom of the package impermeable to fluid flow as well as moisture transfer and adiabatic to heat transfer. The velocity vectors, isotherms and contours of rate of moisture loss were presented during transient cooling as well as at steady state using the commercially available computational fluid dynamics (CFD) code based on the finite volume technique. The CFD model was validated using the experimental data on the time-temperature history as well as weight loss obtained from a bag of potatoes kept in a cold store. The simulated and experimental values on temperature and moisture loss of the product were found to be in good agreement
A Reduced Three Dimensional Model for SAW Sensors Using Finite Element Analysis.
El Gowini, Mohamed M; Moussa, Walied A
2009-01-01
A major problem that often arises in modeling Micro Electro Mechanical Systems (MEMS) such as Surface Acoustic Wave (SAW) sensors using Finite Element Analysis (FEA) is the extensive computational capacity required. In this study a new approach is adopted to significantly reduce the computational capacity needed for analyzing the response of a SAW sensor using the finite element (FE) method. The approach is based on the plane wave solution where the properties of the wave vary in two dimensions and are uniform along the thickness of the device. The plane wave solution therefore allows the thickness of the SAW device model to be minimized; the model is referred to as a Reduced 3D Model (R3D). Various configurations of this novel R3D model are developed and compared with theoretical and experimental frequency data and the results show very good agreement. In addition, two-dimensional (2D) models with similar configurations to the R3D are developed for comparison since the 2D approach is widely adopted in the literature as a computationally inexpensive approach to model SAW sensors using the FE method. Results illustrate that the R3D model is capable of capturing the SAW response more accurately than the 2D model; this is demonstrated by comparison of centre frequency and insertion loss values. These results are very encouraging and indicate that the R3D model is capable of capturing the MEMS-based SAW sensor response without being computationally expensive.
A three-dimensional spectral element model for the solution of the hydrostatic primitive equations
Iskandarani, M; Levin, J C
2003-01-01
We present a spectral element model to solve the hydrostatic primitive equations governing large-scale geophysical flows. The highlights of this new model include unstructured grids, dual h-p paths to convergence, and good scalability characteristics on present day parallel computers including Beowulf-class systems. The behavior of the model is assessed on three process-oriented test problems involving wave propagation, gravitational adjustment, and nonlinear flow rectification, respectively. The first of these test problems is a study of the convergence properties of the model when simulating the linear propagation of baroclinic Kelvin waves. The second is an intercomparison of spectral element and finite-difference model solutions to the adjustment of a density front in a straight channel. Finally, the third problem considers the comparison of model results to measurements obtained from a laboratory simulation of flow around a submarine canyon. The aforementioned tests demonstrate the good performance of th...
Three-Dimensional Model Test Study of the New Breakwaters at Playa Blanca, Lanzarote
DEFF Research Database (Denmark)
Andersen, Thomas Lykke; Garborg, Karsten; Stagsted, Esben Rubech
This report present the results of 3-D physical model tests (length scale 1:42.5) carried out in a wave bassin at Department of Civil Engineering, Aalborg University (AAU) on behalf of SENER Ingenera y Sistemas S.A. Associate Prof. Thomas Lykke Andersen was in charge of the model tests, assisted...... by B.Sc. Karsten Garborg and B.Sc. Esben Rubeck Stagsted. Engineer assistant Niels Drustrup and Leif Mortensen assisted in the laboratory with the construction and instrumentation of the model. The model construction, testing and reporting were performed during August and September 2012. For further...
Parametric analysis of three dimensional flow models applied to tidal energy sites in Scotland
Rahman, Anas; Venugopal, Vengatesan
2017-04-01
This paper presents a detailed parametric analysis on various input parameters of two different numerical models, namely Telemac3D and Delft3D, used for the simulation of tidal current flow at potential tidal energy sites in the Pentland Firth in Scotland. The motivation behind this work is to investigate the influence of the input parameters on the above 3D models, as the majority of past research has mainly focused on using the 2D depth-averaged flow models for this region. An extended description of the models setup, along with the utilised parameters is provided. The International Hydrographic Organisation (IHO) tidal gauges and Acoustic Doppler and Current Profiler (ADCP) measurements are used in calibrating model output to ensure the robustness of the models. Extensive parametric study on the impact of varying drag coefficients, roughness formulae and turbulence models has been investigated and reported. The results indicate that both Telemac3D and Delft3D models are able to produce excellent comparison against measured data; however, with Delft3D, the model parameters which provided higher correlation with the measured data, are found to be different from those reported in the previous literature, which could be attributed to the choice of boundary conditions and the mesh size.
Energy Technology Data Exchange (ETDEWEB)
Atherton, C.S.
1995-01-05
Two of the most important chemically reactive tropospheric gases are ozone (O{sub 3}) and the hydroxyl radical (OH). Although ozone in the stratosphere is a necessary protector against the sun`s radiation, tropospheric ozone is actually a pollutant which damages materials and vegetation, acts as a respiratory irritant, and is a greenhouse gas. One of the two main sources of ozone in the troposphere is photochemical production. The photochemistry is initiated when hydrocarbons and carbon monoxide (CO) react with nitrogen oxides (NO{sub x} = NO + NO{sub 2}) in the presence of sunlight. Reaction with the hydroxyl radical, OH, is the main sink for many tropospheric gases. The hydroxyl radical is highly reactive and has a lifetime on the order of seconds. Its formation is initiated by the photolysis of tropospheric ozone. Tropospheric chemistry involves a complex, non-linear set of chemical reactions between atmospheric species that vary substantially in time and space. To model these and other species on a global scale requires the use of a global, three-dimensional chemistry, transport, and deposition (CTD) model. In this work, I developed two such three dimensional CTD models. The first model incorporated the chemistry necessary to model tropospheric ozone production from the reactions of nitrogen oxides with carbon monoxide (CO) and methane (CH{sub 4}). The second also included longer-lived alkane species and the biogenic hydrocarbon isoprene, which is emitted by growing plants and trees. The models` ability to predict a number of key variables (including the concentration of O{sub 3}, OH, and other species) were evaluated. Then, several scenarios were simulated to understand the change in the chemistry of the troposphere since preindustrial times and the role of anthropogenic NO{sub x} on present day conditions.
Wang, Shuai; Wang, Yu; Zi, Yanyang; Li, Bing; He, Zhengjia
2015-10-01
A novel reduced-order modeling method is presented in this paper for dynamics analysis of rotating impeller-shaft-bearing assembly with cracked impellers. Based on three-dimensional finite element model, the complex component mode synthesis (CMS) method is employed to generate an efficient reduced-order model (ROM) for studying the effects of crack on the global vibration of the rotating assembly. First, a modeling framework for impeller-shaft-bearing systems in rotating frame is presented. Rotational effects, including Coriolis matrix and centrifugal softening, have been taken into account. Then, the governing equation of motion of the damped gyroscopic system is reduced by the complex CMS method. Finally, the obtained ROM is employed to study the effects of crack on assembly's vibration. During the steady-state response analysis, external excitations on the impeller due to rotor-stator interactions have been taken into account, which was however neglected in previous investigations on rotordynamics. Numerical results show that the lower-order eigenvalues and the unbalance response of the assembly are not sensitive to the local crack on impeller. Nevertheless, the flexible coupling between impeller and shaft becomes more complex when the air flow-induced excitations are considered. Under EO1 traveling wave excitations, a crack leads to slight changes in the assembly's response. In contrast, the effect of crack becomes significant when the assembly is excited by EO2 and higher EO excitations. Moreover, the nonlinear crack breathing effects affect the assembly's response obviously. Finally, a potential technique for detecting the crack on impeller during operation is discussed.
A Study of a Three-Dimensional Action Research Training Model for School Library Programs
Gordon, Carol
2006-01-01
This is a detailed review of an in-depth action research training model and an investigation of how that model, supported through virtual and personal guidance from an academic researcher, served to impact the instructional practice of a small sample of school library media specialists (SLMSs). The researcher operates in the third dimension,…
International Nuclear Information System (INIS)
Chen Jian-Lin; Li Lei; Wang Lin-Yuan; Cai Ai-Long; Xi Xiao-Qi; Zhang Han-Ming; Li Jian-Xin; Yan Bin
2015-01-01
The projection matrix model is used to describe the physical relationship between reconstructed object and projection. Such a model has a strong influence on projection and backprojection, two vital operations in iterative computed tomographic reconstruction. The distance-driven model (DDM) is a state-of-the-art technology that simulates forward and back projections. This model has a low computational complexity and a relatively high spatial resolution; however, it includes only a few methods in a parallel operation with a matched model scheme. This study introduces a fast and parallelizable algorithm to improve the traditional DDM for computing the parallel projection and backprojection operations. Our proposed model has been implemented on a GPU (graphic processing unit) platform and has achieved satisfactory computational efficiency with no approximation. The runtime for the projection and backprojection operations with our model is approximately 4.5 s and 10.5 s per loop, respectively, with an image size of 256×256×256 and 360 projections with a size of 512×512. We compare several general algorithms that have been proposed for maximizing GPU efficiency by using the unmatched projection/backprojection models in a parallel computation. The imaging resolution is not sacrificed and remains accurate during computed tomographic reconstruction. (paper)
Budd, Julia M.; LaGrow, Steven J.
2000-01-01
A study investigated the efficacy of using the Buddy Road Kit, an interactive, wooden model, to teach environmental concepts to 4 children with visual impairments ages 7 to 11 years old. Results indicate the model was effective in teaching environmental concepts and traffic safety to the children involved. (Contains references.) (CR)
A three-dimensional fixed grid model for shallow-water flow
Bijvelds, M.D.J.P.
1998-01-01
In this report the implementation and testing of a numerical model that is based on a Cartesian fixed grid in vertical direction is described. The model uses the shallow-water equations and accounts for effects of stratification. In stratified environments, the terrain-following 0-transformation,
Programming Models for Three-Dimensional Hydrodynamics on the CM-5 (Part II)
International Nuclear Information System (INIS)
Amala, P.A.K.; Rodrigue, G.H.
1994-01-01
This is a two-part presentation of a timing study on the Thinking Machines CORP. CM-5 computer. Part II is given in this study and represents domain-decomposition and message-passing models. Part I described computational problems using a SIMD model and connection machine FORTRAN (CMF)
Bezemer-Krijnen, Marieke; Wijnant, Ysbrand H.; de Boer, Andries; Glorieux, C.
2015-01-01
Sound absorption of porous asphalt pavements is an important property when reducing tyre-road noise. A hybrid model has been developed to predict the sound absorption of porous roads. This model is a combination of an analytical analysis of the sound eld and a numerical approach, including both the
Hartmann, Timo; Levitt, R.
2010-01-01
This paper introduces an extant, theoretical, social-psychological model that explains the sense-making processes of project managers confronted with a new technology to improve our understanding of project-based innovation processes. The model represents the interlinked processes through which
Li, Fangzheng; Liu, Chunying; Song, Xuexiong; Huan, Yanjun; Gao, Shansong; Jiang, Zhongling
2018-01-01
Access to adequate anatomical specimens can be an important aspect in learning the anatomy of domestic animals. In this study, the authors utilized a structured light scanner and fused deposition modeling (FDM) printer to produce highly accurate animal skeletal models. First, various components of the bovine skeleton, including the femur, the…
National Research Council Canada - National Science Library
Lottero, Richard
2001-01-01
This report describes the results of three-dimensional (3-D) hydrocode computations modeling the detonation of a donor munitions stack and the loading on and response of a protective water barricade and a nearby acceptor munitions stack...
Three-Dimensional Model Test Study of a CUBIPOD Armoured Roundhead
DEFF Research Database (Denmark)
Burcharth, Hans F.; Andersen, Thomas Lykke; Aldama, J. M. Urrutia
The present report presents results from a three‐dimensional model test study carried out at Aalborg University in the period September 2008 - December 2008. The model tests were carried out to study the stability of a CUBIPOD armoured roundhead under short‐crested wave attack. Few long‐crested w......The present report presents results from a three‐dimensional model test study carried out at Aalborg University in the period September 2008 - December 2008. The model tests were carried out to study the stability of a CUBIPOD armoured roundhead under short‐crested wave attack. Few long......‐crested wave tests were performed as well. One objective of the tests was to compare the stability of CUBIPOD armoured roundheads to the stability of cube armoured roundheads. This could be done by choosing a model test setup identical to that previous used in a study of the stability of a cube armoured...
Directory of Open Access Journals (Sweden)
D. V. Rose
2010-09-01
Full Text Available A 3D fully electromagnetic (EM model of the principal pulsed-power components of a high-current linear transformer driver (LTD has been developed. LTD systems are a relatively new modular and compact pulsed-power technology based on high-energy density capacitors and low-inductance switches located within a linear-induction cavity. We model 1-MA, 100-kV, 100-ns rise-time LTD cavities [A. A. Kim et al., Phys. Rev. ST Accel. Beams 12, 050402 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050402] which can be used to drive z-pinch and material dynamics experiments. The model simulates the generation and propagation of electromagnetic power from individual capacitors and triggered gas switches to a radially symmetric output line. Multiple cavities, combined to provide voltage addition, drive a water-filled coaxial transmission line. A 3D fully EM model of a single 1-MA 100-kV LTD cavity driving a simple resistive load is presented and compared to electrical measurements. A new model of the current loss through the ferromagnetic cores is developed for use both in circuit representations of an LTD cavity and in the 3D EM simulations. Good agreement between the measured core current, a simple circuit model, and the 3D simulation model is obtained. A 3D EM model of an idealized ten-cavity LTD accelerator is also developed. The model results demonstrate efficient voltage addition when driving a matched impedance load, in good agreement with an idealized circuit model.
Evaluation of cloud convection and tracer transport in a three-dimensional chemical transport model
Directory of Open Access Journals (Sweden)
W. Feng
2011-06-01
Full Text Available We investigate the performance of cloud convection and tracer transport in a global off-line 3-D chemical transport model. Various model simulations are performed using different meteorological (reanalyses (ERA-40, ECMWF operational and ECMWF Interim to diagnose the updraft mass flux, convective precipitation and cloud top height.
The diagnosed upward mass flux distribution from TOMCAT agrees quite well with the ECMWF reanalysis data (ERA-40 and ERA-Interim below 200 hPa. Inclusion of midlevel convection improves the agreement at mid-high latitudes. However, the reanalyses show strong convective transport up to 100 hPa, well into the tropical tropopause layer (TTL, which is not captured by TOMCAT. Similarly, the model captures the spatial and seasonal variation of convective cloud top height although the mean modelled value is about 2 km lower than observed.
The ERA-Interim reanalyses have smaller archived upward convective mass fluxes than ERA-40, and smaller convective precipitation, which is in better agreement with satellite-based data. TOMCAT captures these relative differences when diagnosing convection from the large-scale fields. The model also shows differences in diagnosed convection with the version of the operational analyses used, which cautions against using results of the model from one specific time period as a general evaluation.
We have tested the effect of resolution on the diagnosed modelled convection with simulations ranging from 5.6° × 5.6° to 1° × 1°. Overall, in the off-line model, the higher model resolution gives stronger vertical tracer transport, however, it does not make a large change to the diagnosed convective updraft mass flux (i.e., the model results using the convection scheme fail to capture the strong convection transport up to 100 hPa as seen in the archived convective mass fluxes. Similarly, the resolution of the forcing winds in the higher resolution CTM does not make a
Porto, Betina Grehs; Porto, Thiago Soares; Silva, Monica Barros; Grehs, Renésio Armindo; Pinto, Ary dos Santos; Bhandi, Shilpa H; Tonetto, Mateus Rodrigues; Bandéca, Matheus Coelho; dos Santos-Pinto, Lourdes Aparecida Martins
2014-11-01
Digital models are an alternative for carrying out analyses and devising treatment plans in orthodontics. The objective of this study was to evaluate the accuracy and the reproducibility of measurements of tooth sizes, interdental distances and analyses of occlusion using plaster models and their digital images. Thirty pairs of plaster models were chosen at random, and the digital images of each plaster model were obtained using a laser scanner (3Shape R-700, 3Shape A/S). With the plaster models, the measurements were taken using a caliper (Mitutoyo Digimatic(®), Mitutoyo (UK) Ltd) and the MicroScribe (MS) 3DX (Immersion, San Jose, Calif). For the digital images, the measurement tools used were those from the O3d software (Widialabs, Brazil). The data obtained were compared statistically using the Dahlberg formula, analysis of variance and the Tukey test (p < 0.05). The majority of the measurements, obtained using the caliper and O3d were identical, and both were significantly different from those obtained using the MS. Intra-examiner agreement was lowest when using the MS. The results demonstrated that the accuracy and reproducibility of the tooth measurements and analyses from the plaster models using the caliper and from the digital models using O3d software were identical.
Directory of Open Access Journals (Sweden)
Fukushima Kensuke
2017-01-01
Full Text Available Introduction: Periacetabular osteotomy (PAO is an effective joint-preserving procedure for young adults with developmental dysplasia of the hip. Although PAO provides excellent radiographic and clinical results, it is a technically demanding procedure with a distinct learning curve that requires careful 3D planning and, above all, has a number of potential complications. We therefore developed a pre-operative simulation method for PAO via creation of a new full-scale model. Methods: The model was prepared from the patient’s Digital Imaging and Communications in Medicine (DICOM formatted data from computed tomography (CT, for construction and assembly using 3D printing technology. A major feature of our model is that it is constructed from salt. In contrast to conventional models, our model provides a more accurate representation, at a lower manufacturing cost, and requires a shorter production time. Furthermore, our model realized simulated operation normally with using a chisel and drill without easy breakage or fissure. We were able to easily simulate the line of osteotomy and confirm acetabular version and coverage after moving to the osteotomized fragment. Additionally, this model allowed a dynamic assessment that avoided anterior impingement following the osteotomy. Results: Our models clearly reflected the anatomical shape of the patient’s hip. Our models allowed for surgical simulation, making realistic use of the chisel and drill. Our method of pre-operative simulation for PAO allowed for the assessment of accurate osteotomy line, determination of the position of the osteotomized fragment, and prevented anterior impingement after the operation. Conclusion: Our method of pre-operative simulation might improve the safety, accuracy, and results of PAO.
International Nuclear Information System (INIS)
Li, Y F; Wang, G L; Lu, Z S; Shao, D X
2006-01-01
A contact model and corresponding numerical method are proposed in this paper to study the influences of contact deformations on stiffness measuring precision of spring tubes. Firstly, measuring principle and the force analysis are presented. Then, the contact model is set up by simplifying the contact force and considering the real contact condition. Lastly, a numerical method is developed to solve the contact equation, and quantizing relationships between measurement errors and the contact deformation are derived subsequently. It's proved by simulation and tests that the contact model is more accurate than Herzian contact theory and the contact deformation can make stiffness values lower than its true ones
Highway three-dimensional modeling based on Vehicle-borne laser data
International Nuclear Information System (INIS)
Weili, Sun; Ruofei, Zhong; Jiangxia, Wei; Fanyang, Zeng
2014-01-01
The of Vehicle-borne LiDAR (Light Detection And Ranging) scanning technology is an efficiently practical approach on the acquisition and application of 3D information and its geographic elements of highway(including road surface, rails, attached facilities, slopes, ditches, etc.). The acquired information is significant on many aspects such as road maintenance, reconstruction, survey, landscape design, visualized modelling and highway hazard supervision and prevention. The initial laser data cannot be directly used to construct highway 3D model, operations of pre-processing are necessary. This paper presented a set of procedure about pre-processing laser data and constructing TIN (Triangle Irregular Net) model of highway
Evidence Meshes for Three-Dimensional Modeling, Visualization, and Navigation, Phase I
National Aeronautics and Space Administration — As robots are tasked with ever more complex missions, they demand more sophisticated models of the environments in which they must work. Rough-terrain mobility, site...
Three-Dimensional Model of a Muscle and Simulation of its Surface EMG
National Research Council Canada - National Science Library
Schnetzer, M
2001-01-01
...) and a simulation of its surface EMG. The simulations are part of a larger model including in addition the input system to the motoneuronal pool, the motoneuronal pool itself and the force generating mechanism...
Residual estuarine circulation in the Mandovi, a monsoonal estuary: A three-dimensional model study
Digital Repository Service at National Institute of Oceanography (India)
Vijith, V.; Shetye, S.R.; Baetens, K.; Luyten, P.; Michael, G.S.
then analyse the model results to define characteristics of residual estuarine circulation in the Mandovi. Our motivation to study this aspect of the Mandovi`s dynamics is derived from the following three considerations. First, residual circulation is important...
Nonequilibrium behaviors of the three-dimensional Heisenberg model in the Swendsen-Wang algorithm
Nonomura, Yoshihiko; Tomita, Yusuke
2016-01-01
Recently, it was shown [Y. Nonomura, J. Phys. Soc. Jpn. 83, 113001 (2014), 10.7566/JPSJ.83.113001] that the nonequilibrium critical relaxation of the two-dimensional (2D) Ising model from a perfectly ordered state in the Wolff algorithm is described by stretched-exponential decay, and a universal scaling scheme was found to connect nonequilibrium and equilibrium behaviors. In the present study we extend these findings to vector spin models, and the 3D Heisenberg model could be a typical example. To evaluate the critical temperature and critical exponents precisely using the above scaling scheme, we calculate nonequilibrium ordering from the perfectly disordered state in the Swendsen-Wang algorithm, and we find that the critical ordering process is described by stretched-exponential growth with a comparable exponent to that of the 3D X Y model. The critical exponents evaluated in the present study are consistent with those in previous studies.
AUTOMATING THREE DIMENSIONAL (3D) MODEL CREATION OF CIRCUIT CARD ASSEMBLIES
2017-07-01
If done correctly, both decals will now appear with the proper orientation, verifiable by the proper alignment of the through holes to decal...Figure 3 shows a properly aligned graphical decal of the solid board model. Figure 3 Printed wiring board with decal Now that a model of the... interference between CCA components and features of other CCAs or parts, insufficient clearances with CCA enclosure, misaligned mounting holes
A three-dimensional model for calculating the micro disk laser resonant-modes
International Nuclear Information System (INIS)
Sabetjoo, H.; Bahrampor, A.; Farrahi-Moghaddam, R.
2006-01-01
In this article, a semi-analytical model for theoretical analysis of micro disk lasers is presented. Using this model, the necessary conditions for the existence of loss less and low-loss modes of micro-resonators are obtained. The resonance frequency of the resonant modes and also the attenuation of low-loss modes are calculated. By comparing the results with results of finite difference method, their validity is certified.
The accuracy of a method for printing three-dimensional spinal models.
Directory of Open Access Journals (Sweden)
Ai-Min Wu
Full Text Available To study the morphology of the human spine and new spinal fixation methods, scientists require cadaveric specimens, which are dependent on donation. However, in most countries, the number of people willing to donate their body is low. A 3D printed