Gust Acoustics Computation with a Space-Time CE/SE Parallel 3D Solver

NASA Technical Reports Server (NTRS)

Wang, X. Y.; Himansu, A.; Chang, S. C.; Jorgenson, P. C. E.; Reddy, D. R. (Technical Monitor)

2002-01-01

The benchmark Problem 2 in Category 3 of the Third Computational Aero-Acoustics (CAA) Workshop is solved using the space-time conservation element and solution element (CE/SE) method. This problem concerns the unsteady response of an isolated finite-span swept flat-plate airfoil bounded by two parallel walls to an incident gust. The acoustic field generated by the interaction of the gust with the flat-plate airfoil is computed by solving the 3D (three-dimensional) Euler equations in the time domain using a parallel version of a 3D CE/SE solver. The effect of the gust orientation on the far-field directivity is studied. Numerical solutions are presented and compared with analytical solutions, showing a reasonable agreement.

Boundary Layer Model for Air Pollutant Concentrations Due to Highway Traffic

ERIC Educational Resources Information Center

Ragland, Kenneth W.; Peirce, J. Jeffrey

1975-01-01

A numerical solution of the three-dimensional steady-state diffusion equation for a finite width line source is presented. The wind speed and eddy diffusivity as a function of height above the roadway are obtained. Normalized ground level and elevated concentrations near a highway are obtained for winds perpendicular, parallel, and at 45 degrees.…

HPCC Methodologies for Structural Design and Analysis on Parallel and Distributed Computing Platforms

NASA Technical Reports Server (NTRS)

Farhat, Charbel

1998-01-01

In this grant, we have proposed a three-year research effort focused on developing High Performance Computation and Communication (HPCC) methodologies for structural analysis on parallel processors and clusters of workstations, with emphasis on reducing the structural design cycle time. Besides consolidating and further improving the FETI solver technology to address plate and shell structures, we have proposed to tackle the following design related issues: (a) parallel coupling and assembly of independently designed and analyzed three-dimensional substructures with non-matching interfaces, (b) fast and smart parallel re-analysis of a given structure after it has undergone design modifications, (c) parallel evaluation of sensitivity operators (derivatives) for design optimization, and (d) fast parallel analysis of mildly nonlinear structures. While our proposal was accepted, support was provided only for one year.

Field theoretic approach to roughness corrections

NASA Astrophysics Data System (ADS)

Wu, Hua Yao; Schaden, Martin

2012-02-01

We develop a systematic field theoretic description of roughness corrections to the Casimir free energy of a massless scalar field in the presence of parallel plates with mean separation a. Roughness is modeled by specifying a generating functional for correlation functions of the height profile. The two-point correlation function being characterized by its variance, σ2, and correlation length, ℓ. We obtain the partition function of a massless scalar quantum field interacting with the height profile of the surface via a δ-function potential. The partition function is given by a holographic reduction of this model to three coupled scalar fields on a two-dimensional plane. The original three-dimensional space with a flat parallel plate at a distance a from the rough plate is encoded in the nonlocal propagators of the surface fields on its boundary. Feynman rules for this equivalent 2+1-dimensional model are derived and its counterterms constructed. The two-loop contribution to the free energy of this model gives the leading roughness correction. The effective separation, aeff, to a rough plate is measured to a plane that is displaced a distance ρ∝σ2/ℓ from the mean of its profile. This definition of the separation eliminates corrections to the free energy of order 1/a4 and results in unitary scattering matrices. We obtain an effective low-energy model in the limit ℓ≪a. It determines the scattering matrix and equivalent planar scattering surface of a very rough plate in terms of the single length scale ρ. The Casimir force on a rough plate is found to always weaken with decreasing correlation length ℓ. The two-loop approximation to the free energy interpolates between the free energy of the effective low-energy model and that of the proximity force approximation - the force on a very rough plate with σ≳0.5ℓ being weaker than on a planar Dirichlet surface at any separation.

Subduction Thermal Regime, Slab Dehydration, and Seismicity Distribution Beneath Hikurangi Based on 3-D Simulations

NASA Astrophysics Data System (ADS)

Suenaga, Nobuaki; Ji, Yingfeng; Yoshioka, Shoichi; Feng, Deshan

2018-04-01

The downdip limit of seismogenic interfaces inferred from the subduction thermal regime by thermal models has been suggested to relate to the faulting instability caused by the brittle failure regime in various plate convergent systems. However, the featured three-dimensional thermal state, especially along the horizontal (trench-parallel) direction of a subducted oceanic plate, remains poorly constrained. To robustly investigate and further map the horizontal (trench-parallel) distribution of the subduction regime and subsequently induced slab dewatering in a descending plate beneath a convergent margin, we construct a regional thermal model that incorporates an up-to-date three-dimensional slab geometry and the MORVEL plate velocity to simulate the plate subduction history in Hikurangi. Our calculations suggest an identified thrust zone featuring remarkable slab dehydration near the Taupo volcanic arc in the North Island distributed in the Kapiti, Manawatu, and Raukumara region. The calculated average subduction-associated slab dehydration of 0.09 to 0.12 wt%/km is greater than the dehydration in other portions of the descending slab and possibly contributes to an along-arc variation in the interplate pore fluid pressure. A large-scale slab dehydration (>0.05 wt%/km) and a high thermal gradient (>4 °C/km) are also identified in the Kapiti, Manawatu, and Raukumara region and are associated with frequent deep slow slip events. An intraslab dehydration that exceeds 0.2 wt%/km beneath Manawatu near the source region of tectonic tremors suggests an unknown relationship in the genesis of slow earthquakes.

Telescoping tube assembly

NASA Technical Reports Server (NTRS)

Sturm, Albert J. (Inventor); Marrinan, Thomas E. (Inventor)

1995-01-01

An extensible and retractable telescoping tube positions test devices that inspect large stationary objects. The tube has three dimensional adjustment capabilities and is vertically suspended from a frame. The tube sections are independently supported with each section comprising U-shaped housing secured to a thicker support plate. Guide mechanisms preferably mounted only to the thicker plates guide each tube section parallel to a reference axis with improved accuracy so that the position of the remote end of the telescoping tube is precisely known.

A lattice relaxation algorithm for three-dimensional Poisson-Nernst-Planck theory with application to ion transport through the gramicidin A channel.

PubMed Central

Kurnikova, M G; Coalson, R D; Graf, P; Nitzan, A

1999-01-01

A lattice relaxation algorithm is developed to solve the Poisson-Nernst-Planck (PNP) equations for ion transport through arbitrary three-dimensional volumes. Calculations of systems characterized by simple parallel plate and cylindrical pore geometries are presented in order to calibrate the accuracy of the method. A study of ion transport through gramicidin A dimer is carried out within this PNP framework. Good agreement with experimental measurements is obtained. Strengths and weaknesses of the PNP approach are discussed. PMID:9929470

Design of an open-ended plenoptic camera for three-dimensional imaging of dusty plasmas

NASA Astrophysics Data System (ADS)

Sanpei, Akio; Tokunaga, Kazuya; Hayashi, Yasuaki

2017-08-01

Herein, the design of a plenoptic imaging system for three-dimensional reconstructions of dusty plasmas using an integral photography technique has been reported. This open-ended system is constructed with a multi-convex lens array and a typical reflex CMOS camera. We validated the design of the reconstruction system using known target particles. Additionally, the system has been applied to observations of fine particles floating in a horizontal, parallel-plate radio-frequency plasma. Furthermore, the system works well in the range of our dusty plasma experiment. We can identify the three-dimensional positions of dust particles from a single-exposure image obtained from one viewing port.

New 2D diffraction model and its applications to terahertz parallel-plate waveguide power splitters

PubMed Central

Zhang, Fan; Song, Kaijun; Fan, Yong

2017-01-01

A two-dimensional (2D) diffraction model for the calculation of the diffraction field in 2D space and its applications to terahertz parallel-plate waveguide power splitters are proposed in this paper. Compared with the Huygens-Fresnel principle in three-dimensional (3D) space, the proposed model provides an approximate analytical expression to calculate the diffraction field in 2D space. The diffraction filed is regarded as the superposition integral in 2D space. The calculated results obtained from the proposed diffraction model agree well with the ones by software HFSS based on the element method (FEM). Based on the proposed 2D diffraction model, two parallel-plate waveguide power splitters are presented. The splitters consist of a transmitting horn antenna, reflectors, and a receiving antenna array. The reflector is cylindrical parabolic with superimposed surface relief to efficiently couple the transmitted wave into the receiving antenna array. The reflector is applied as computer-generated holograms to match the transformed field to the receiving antenna aperture field. The power splitters were optimized by a modified real-coded genetic algorithm. The computed results of the splitters agreed well with the ones obtained by software HFSS verify the novel design method for power splitter, which shows good applied prospects of the proposed 2D diffraction model. PMID:28181514

Impact of local diffusion on macroscopic dispersion in three-dimensional porous media

NASA Astrophysics Data System (ADS)

Dartois, Arthur; Beaudoin, Anthony; Huberson, Serge

2018-02-01

While macroscopic longitudinal and transverse dispersion in three-dimensional porous media has been simulated previously mostly under purely advective conditions, the impact of diffusion on macroscopic dispersion in 3D remains an open question. Furthermore, both in 2D and 3D, recurring difficulties have been encountered due to computer limitation or analytical approximation. In this work, we use the Lagrangian velocity covariance function and the temporal derivative of second-order moments to study the influence of diffusion on dispersion in highly heterogeneous 2D and 3D porous media. The first approach characterizes the correlation between the values of Eulerian velocity components sampled by particles undergoing diffusion at two times. The second approach allows the estimation of dispersion coefficients and the analysis of their behaviours as functions of diffusion. These two approaches allowed us to reach new results. The influence of diffusion on dispersion seems to be globally similar between highly heterogeneous 2D and 3D porous media. Diffusion induces a decrease in the dispersion in the direction parallel to the flow direction and an increase in the dispersion in the direction perpendicular to the flow direction. However, the amplification of these two effects with the permeability variance is clearly different between 2D and 3D. For the direction parallel to the flow direction, the amplification is more important in 3D than in 2D. It is reversed in the direction perpendicular to the flow direction.

Investigating axial diffusion in cylindrical pores using confocal single-particle fluorescence correlation spectroscopy.

PubMed

Chen, Fang; Neupane, Bhanu; Li, Peiyuan; Su, Wei; Wang, Gufeng

2016-08-01

We explored the feasibility of using confocal fluorescence correlation spectroscopy to study small nanoparticle diffusion in hundred-nanometer-sized cylindrical pores. By modeling single particle diffusion in tube-like confined three-dimensional space aligned parallel to the confocal optical axis, we showed that two diffusion dynamics can be observed in both original intensity traces and the autocorrelation functions (ACFs): the confined two-dimensional lateral diffusion and the unconfined one-dimensional (1D) axial diffusion. The separation of the axial and confined lateral diffusion dynamics provides an opportunity to study diffusions in different dimensions separately. We further experimentally studied 45 nm carboxylated polystyrene particles diffusing in 300 nm alumina pores. The experimental data showed consistency with the simulation. To extract the accurate axial diffusion coefficient, we found that a 1D diffusion model with a Lorentzian axial collection profile needs to be used to analyze the experimental ACFs. The diffusion of the 45 nm nanoparticles in polyethyleneglycol-passivated 300 nm pores slowed down by a factor of ∼2, which can be satisfactorily explained by hydrodynamic frictions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Two Colorable Fourth Order Compact Difference Scheme and Parallel Iterative Solution of the 3D Convection Diffusion Equation

NASA Technical Reports Server (NTRS)

Zhang, Jun; Ge, Lixin; Kouatchou, Jules

2000-01-01

A new fourth order compact difference scheme for the three dimensional convection diffusion equation with variable coefficients is presented. The novelty of this new difference scheme is that it Only requires 15 grid points and that it can be decoupled with two colors. The entire computational grid can be updated in two parallel subsweeps with the Gauss-Seidel type iterative method. This is compared with the known 19 point fourth order compact differenCe scheme which requires four colors to decouple the computational grid. Numerical results, with multigrid methods implemented on a shared memory parallel computer, are presented to compare the 15 point and the 19 point fourth order compact schemes.

Heterodyne frequency-domain multispectral diffuse optical tomography of breast cancer in the parallel-plane transmission geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ban, H. Y.; Kavuri, V. C., E-mail: venk@physics.up

Purpose: The authors introduce a state-of-the-art all-optical clinical diffuse optical tomography (DOT) imaging instrument which collects spatially dense, multispectral, frequency-domain breast data in the parallel-plate geometry. Methods: The instrument utilizes a CCD-based heterodyne detection scheme that permits massively parallel detection of diffuse photon density wave amplitude and phase for a large number of source–detector pairs (10{sup 6}). The stand-alone clinical DOT instrument thus offers high spatial resolution with reduced crosstalk between absorption and scattering. Other novel features include a fringe profilometry system for breast boundary segmentation, real-time data normalization, and a patient bed design which permits both axial and sagittalmore » breast measurements. Results: The authors validated the instrument using tissue simulating phantoms with two different chromophore-containing targets and one scattering target. The authors also demonstrated the instrument in a case study breast cancer patient; the reconstructed 3D image of endogenous chromophores and scattering gave tumor localization in agreement with MRI. Conclusions: Imaging with a novel parallel-plate DOT breast imager that employs highly parallel, high-resolution CCD detection in the frequency-domain was demonstrated.« less

Parallel 3-D numerical simulation of dielectric barrier discharge plasma actuators

NASA Astrophysics Data System (ADS)

Houba, Tomas

Dielectric barrier discharge plasma actuators have shown promise in a range of applications including flow control, sterilization and ozone generation. Developing numerical models of plasma actuators is of great importance, because a high-fidelity parallel numerical model allows new design configurations to be tested rapidly. Additionally, it provides a better understanding of the plasma actuator physics which is useful for further innovation. The physics of plasma actuators is studied numerically. A loosely coupled approach is utilized for the coupling of the plasma to the neutral fluid. The state of the art in numerical plasma modeling is advanced by the development of a parallel, three-dimensional, first-principles model with detailed air chemistry. The model incorporates 7 charged species and 18 reactions, along with a solution of the electron energy equation. To the author's knowledge, a parallel three-dimensional model of a gas discharge with a detailed air chemistry model and the solution of electron energy is unique. Three representative geometries are studied using the gas discharge model. The discharge of gas between two parallel electrodes is used to validate the air chemistry model developed for the gas discharge code. The gas discharge model is then applied to the discharge produced by placing a dc powered wire and grounded plate electrodes in a channel. Finally, a three-dimensional simulation of gas discharge produced by electrodes placed inside a riblet is carried out. The body force calculated with the gas discharge model is loosely coupled with a fluid model to predict the induced flow inside the riblet.

In Situ Three-Dimensional Reciprocal-Space Mapping of Diffuse Scattering Intensity Distribution and Data Analysis for Precursor Phenomenon in Shape-Memory Alloy

NASA Astrophysics Data System (ADS)

Cheng, Tian-Le; Ma, Fengde D.; Zhou, Jie E.; Jennings, Guy; Ren, Yang; Jin, Yongmei M.; Wang, Yu U.

2012-01-01

Diffuse scattering contains rich information on various structural disorders, thus providing a useful means to study the nanoscale structural deviations from the average crystal structures determined by Bragg peak analysis. Extraction of maximal information from diffuse scattering requires concerted efforts in high-quality three-dimensional (3D) data measurement, quantitative data analysis and visualization, theoretical interpretation, and computer simulations. Such an endeavor is undertaken to study the correlated dynamic atomic position fluctuations caused by thermal vibrations (phonons) in precursor state of shape-memory alloys. High-quality 3D diffuse scattering intensity data around representative Bragg peaks are collected by using in situ high-energy synchrotron x-ray diffraction and two-dimensional digital x-ray detector (image plate). Computational algorithms and codes are developed to construct the 3D reciprocal-space map of diffuse scattering intensity distribution from the measured data, which are further visualized and quantitatively analyzed to reveal in situ physical behaviors. Diffuse scattering intensity distribution is explicitly formulated in terms of atomic position fluctuations to interpret the experimental observations and identify the most relevant physical mechanisms, which help set up reduced structural models with minimal parameters to be efficiently determined by computer simulations. Such combined procedures are demonstrated by a study of phonon softening phenomenon in precursor state and premartensitic transformation of Ni-Mn-Ga shape-memory alloy.

Reconciling surface plate motions with rapid three-dimensional mantle flow around a slab edge.

PubMed

Jadamec, Margarete A; Billen, Magali I

2010-05-20

The direction of tectonic plate motion at the Earth's surface and the flow field of the mantle inferred from seismic anisotropy are well correlated globally, suggesting large-scale coupling between the mantle and the surface plates. The fit is typically poor at subduction zones, however, where regional observations of seismic anisotropy suggest that the direction of mantle flow is not parallel to and may be several times faster than plate motions. Here we present three-dimensional numerical models of buoyancy-driven deformation with realistic slab geometry for the Alaska subduction-transform system and use them to determine the origin of this regional decoupling of flow. We find that near a subduction zone edge, mantle flow velocities can have magnitudes of more than ten times the surface plate motions, whereas surface plate velocities are consistent with plate motions and the complex mantle flow field is consistent with observations from seismic anisotropy. The seismic anisotropy observations constrain the shape of the eastern slab edge and require non-Newtonian mantle rheology. The incorporation of the non-Newtonian viscosity results in mantle viscosities of 10(17) to 10(18) Pa s in regions of high strain rate (10(-12) s(-1)), and this low viscosity enables the mantle flow field to decouple partially from the motion of the surface plates. These results imply local rapid transport of geochemical signatures through subduction zones and that the internal deformation of slabs decreases the slab-pull force available to drive subducting plates.

Transport of cosmic-ray protons in intermittent heliospheric turbulence: Model and simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alouani-Bibi, Fathallah; Le Roux, Jakobus A., E-mail: fb0006@uah.edu

The transport of charged energetic particles in the presence of strong intermittent heliospheric turbulence is computationally analyzed based on known properties of the interplanetary magnetic field and solar wind plasma at 1 astronomical unit. The turbulence is assumed to be static, composite, and quasi-three-dimensional with a varying energy distribution between a one-dimensional Alfvénic (slab) and a structured two-dimensional component. The spatial fluctuations of the turbulent magnetic field are modeled either as homogeneous with a Gaussian probability distribution function (PDF), or as intermittent on large and small scales with a q-Gaussian PDF. Simulations showed that energetic particle diffusion coefficients both parallelmore » and perpendicular to the background magnetic field are significantly affected by intermittency in the turbulence. This effect is especially strong for parallel transport where for large-scale intermittency results show an extended phase of subdiffusive parallel transport during which cross-field transport diffusion dominates. The effects of intermittency are found to depend on particle rigidity and the fraction of slab energy in the turbulence, yielding a perpendicular to parallel mean free path ratio close to 1 for large-scale intermittency. Investigation of higher order transport moments (kurtosis) indicates that non-Gaussian statistical properties of the intermittent turbulent magnetic field are present in the parallel transport, especially for low rigidity particles at all times.« less

A one-dimensional heat transfer model for parallel-plate thermoacoustic heat exchangers.

PubMed

de Jong, J A; Wijnant, Y H; de Boer, A

2014-03-01

A one-dimensional (1D) laminar oscillating flow heat transfer model is derived and applied to parallel-plate thermoacoustic heat exchangers. The model can be used to estimate the heat transfer from the solid wall to the acoustic medium, which is required for the heat input/output of thermoacoustic systems. The model is implementable in existing (quasi-)1D thermoacoustic codes, such as DeltaEC. Examples of generated results show good agreement with literature results. The model allows for arbitrary wave phasing; however, it is shown that the wave phasing does not significantly influence the heat transfer.

VizieR Online Data Catalog: Solar wind 3D magnetohydrodynamic simulation (Chhiber+, 2017)

NASA Astrophysics Data System (ADS)

Chhiber, R.; Subedi, P.; Usmanov, A. V.; Matthaeus, W. H.; Ruffolo, D.; Goldstein, M. L.; Parashar, T. N.

2017-08-01

We use a three-dimensional magnetohydrodynamic simulation of the solar wind to calculate cosmic-ray diffusion coefficients throughout the inner heliosphere (2Rȯ-3au). The simulation resolves large-scale solar wind flow, which is coupled to small-scale fluctuations through a turbulence model. Simulation results specify background solar wind fields and turbulence parameters, which are used to compute diffusion coefficients and study their behavior in the inner heliosphere. The parallel mean free path (mfp) is evaluated using quasi-linear theory, while the perpendicular mfp is determined from nonlinear guiding center theory with the random ballistic interpretation. Several runs examine varying turbulent energy and different solar source dipole tilts. We find that for most of the inner heliosphere, the radial mfp is dominated by diffusion parallel to the mean magnetic field; the parallel mfp remains at least an order of magnitude larger than the perpendicular mfp, except in the heliospheric current sheet, where the perpendicular mfp may be a few times larger than the parallel mfp. In the ecliptic region, the perpendicular mfp may influence the radial mfp at heliocentric distances larger than 1.5au; our estimations of the parallel mfp in the ecliptic region at 1 au agree well with the Palmer "consensus" range of 0.08-0.3au. Solar activity increases perpendicular diffusion and reduces parallel diffusion. The parallel mfp mostly varies with rigidity (P) as P.33, and the perpendicular mfp is weakly dependent on P. The mfps are weakly influenced by the choice of long-wavelength power spectra. (2 data files).

Assessment of the Biomechanical Performance of 5 Plating Techniques in Fixation of Mandibular Subcondylar Fracture Using Finite Element Analysis.

PubMed

Darwich, Mhd Ayham; Albogha, Mhd Hassan; Abdelmajeed, Adnan; Darwich, Khaldoun

2016-04-01

The aim of this study was to compare the performances of 5 plating techniques for fixation of unilateral mandibular subcondylar fracture. Five titanium plating techniques for fixation of condylar fracture were analyzed using the finite element method. The modeled techniques were 1) 1 straight plate, 2) 2 parallel straight plates, 3) 2 angulated straight plates, 4) 1 trapezoidal plate, and 5) 1 square plate. Three-dimensional models were generated using patient-specific geometry for the mandible obtained from a computerized tomographic image of a healthy living man. Plates were designed and combined with the mandible and analyzed under a 500-N load. The single straight plate presented the most inferior performance; it presented maximum displacement and strain on cortical bone. The trapezoidal plate induced the least amount of strain on cortical bone and was best at resisting displacement. The trapezoidal plate is recommended for fixation of subcondylar fracture. Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Quantifying the effect of hydrogen on dislocation dynamics: A three-dimensional discrete dislocation dynamics framework

NASA Astrophysics Data System (ADS)

Gu, Yejun; El-Awady, Jaafar A.

2018-03-01

We present a new framework to quantify the effect of hydrogen on dislocations using large scale three-dimensional (3D) discrete dislocation dynamics (DDD) simulations. In this model, the first order elastic interaction energy associated with the hydrogen-induced volume change is accounted for. The three-dimensional stress tensor induced by hydrogen concentration, which is in equilibrium with respect to the dislocation stress field, is derived using the Eshelby inclusion model, while the hydrogen bulk diffusion is treated as a continuum process. This newly developed framework is utilized to quantify the effect of different hydrogen concentrations on the dynamics of a glide dislocation in the absence of an applied stress field as well as on the spacing between dislocations in an array of parallel edge dislocations. A shielding effect is observed for materials having a large hydrogen diffusion coefficient, with the shield effect leading to the homogenization of the shrinkage process leading to the glide loop maintaining its circular shape, as well as resulting in a decrease in dislocation separation distances in the array of parallel edge dislocations. On the other hand, for materials having a small hydrogen diffusion coefficient, the high hydrogen concentrations around the edge characters of the dislocations act to pin them. Higher stresses are required to be able to unpin the dislocations from the hydrogen clouds surrounding them. Finally, this new framework can open the door for further large scale studies on the effect of hydrogen on the different aspects of dislocation-mediated plasticity in metals. With minor modifications of the current formulations, the framework can also be extended to account for general inclusion-induced stress field in discrete dislocation dynamics simulations.

Three-dimensional Numerical Models of the Cocos-northern Nazca Slab Gap

NASA Astrophysics Data System (ADS)

Jadamec, M.; Fischer, K. M.

2012-12-01

In contrast to anisotropy beneath the middle of oceanic plates, seismic observations in subduction zones often indicate mantle flow patterns that are not easily explained by simple coupling of the subducting and overriding plates to the mantle. For example, in the Costa Rica-Nicaragua subduction zone local S shear wave splitting measurements combined with geochemical data indicate trench parallel flow in the mantle wedge with flow rates of 6.3-19 cm/yr, which is on order of or may be up to twice the subducting plate velocity. We construct geographically referenced high-resolution three-dimensional (3D) geodynamic models of the Cocos-northern Nazca subduction system to investigate what is driving the northwest directed, and apparently rapid, trench-parallel flow in the mantle wedge beneath Costa Rica-Nicaragua. We use the SlabGenerator code to construct a 3D plate configuration that is used as input to the community mantle convection code, CitcomCU. Models are run on over 400 CPUs on XSEDE, with a mesh resolution of up to 3 km at the plate boundary. Seismicity and seismic tomography delineate the shape and depth of the Cocos and northern Nazca slabs. The subducting plate thermal structure is based on a plate cooling model and ages from the seafloor age grid. Overriding plate thickness is constrained by the ages from the sea floor age grid where available and the depth to the lithosphere-asthenosphere boundary from the greatest negative gradient in absolute shear wave velocity. The geodynamic models test the relative controls of the change in the dip of the Cocos plate and the slab gap between the Cocos and northern Nazca plates in driving the mantle flow beneath Central America. The models also investigate the effect of a non-Newtonian rheology in dynamically generating a low viscosity mantle wedge and how this controls mantle flow rates. To what extent the Cocos-northern Nazca slab gap channelizes mantle flow between Central and South America has direct application to geochemical and geologic studies of the region. In addition, 3D geodynamic models of this kind can further test the hypothesis of rapid mantle flow in subduction zones as a global process and the non-Newtonian rheology as a mechanism for decoupling the mantle from lithospheric plate motion.

Dynamic strain distribution of FRP plate under blast loading

NASA Astrophysics Data System (ADS)

Saburi, T.; Yoshida, M.; Kubota, S.

2017-02-01

The dynamic strain distribution of a fiber re-enforced plastic (FRP) plate under blast loading was investigated using a Digital Image Correlation (DIC) image analysis method. The testing FRP plates were mounted in parallel to each other on a steel frame. 50 g of composition C4 explosive was used as a blast loading source and set in the center of the FRP plates. The dynamic behavior of the FRP plate under blast loading were observed by two high-speed video cameras. The set of two high-speed video image sequences were used to analyze the FRP three-dimensional strain distribution by means of DIC method. A point strain profile extracted from the analyzed strain distribution data was compared with a directly observed strain profile using a strain gauge and it was shown that the strain profile under the blast loading by DIC method is quantitatively accurate.

Modelling Detailed-Chemistry Effects on Turbulent Diffusion Flames using a Parallel Solution-Adaptive Scheme

NASA Astrophysics Data System (ADS)

Jha, Pradeep Kumar

Capturing the effects of detailed-chemistry on turbulent combustion processes is a central challenge faced by the numerical combustion community. However, the inherent complexity and non-linear nature of both turbulence and chemistry require that combustion models rely heavily on engineering approximations to remain computationally tractable. This thesis proposes a computationally efficient algorithm for modelling detailed-chemistry effects in turbulent diffusion flames and numerically predicting the associated flame properties. The cornerstone of this combustion modelling tool is the use of parallel Adaptive Mesh Refinement (AMR) scheme with the recently proposed Flame Prolongation of Intrinsic low-dimensional manifold (FPI) tabulated-chemistry approach for modelling complex chemistry. The effect of turbulence on the mean chemistry is incorporated using a Presumed Conditional Moment (PCM) approach based on a beta-probability density function (PDF). The two-equation k-w turbulence model is used for modelling the effects of the unresolved turbulence on the mean flow field. The finite-rate of methane-air combustion is represented here by using the GRI-Mech 3.0 scheme. This detailed mechanism is used to build the FPI tables. A state of the art numerical scheme based on a parallel block-based solution-adaptive algorithm has been developed to solve the Favre-averaged Navier-Stokes (FANS) and other governing partial-differential equations using a second-order accurate, fully-coupled finite-volume formulation on body-fitted, multi-block, quadrilateral/hexahedral mesh for two-dimensional and three-dimensional flow geometries, respectively. A standard fourth-order Runge-Kutta time-marching scheme is used for time-accurate temporal discretizations. Numerical predictions of three different diffusion flames configurations are considered in the present work: a laminar counter-flow flame; a laminar co-flow diffusion flame; and a Sydney bluff-body turbulent reacting flow. Comparisons are made between the predicted results of the present FPI scheme and Steady Laminar Flamelet Model (SLFM) approach for diffusion flames. The effects of grid resolution on the predicted overall flame solutions are also assessed. Other non-reacting flows have also been considered to further validate other aspects of the numerical scheme. The present schemes predict results which are in good agreement with published experimental results and reduces the computational cost involved in modelling turbulent diffusion flames significantly, both in terms of storage and processing time.

Analysis of absorption and reflection mechanisms in a three-dimensional plate silencer

NASA Astrophysics Data System (ADS)

Wang, Chunqi; Huang, Lixi

2008-06-01

When a segment of a rigid duct is replaced by a plate backed by a hard-walled cavity, grazing incident sound waves induce plate vibration, hence sound reflection. Based on this mechanism, a broadband plate silencer, which works effectively from low-to-medium frequencies have been developed recently. A typical plate silencer consists of an expansion chamber with two side-branch cavities covered by light but extremely stiff plates. Such a configuration is two-dimensional in nature. In this paper, numerical study is extended to three-dimensional configurations to investigate the potential improvement in sound reflection. Finite element simulation shows that the three-dimensional configurations perform better than the corresponding two-dimensional design, especially in the relatively high frequency region. Further analysis shows that the three-dimensional design gives better plate response at higher axial modes than the simple two-dimensional design. Sound absorption mechanism is also introduced to the plate silencer by adding two dissipative chambers on the two lateral sides of a two-cavity wave reflector, hence a hybrid silencer. Numerical simulation shows that the proposed hybrid silencer is able to achieve a good moderate bandwidth with much reduced total length in comparison with pure absorption design.

THE EFFECT OF INTERMITTENT GYRO-SCALE SLAB TURBULENCE ON PARALLEL AND PERPENDICULAR COSMIC-RAY TRANSPORT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Le Roux, J. A.

Earlier work based on nonlinear guiding center (NLGC) theory suggested that perpendicular cosmic-ray transport is diffusive when cosmic rays encounter random three-dimensional magnetohydrodynamic turbulence dominated by uniform two-dimensional (2D) turbulence with a minor uniform slab turbulence component. In this approach large-scale perpendicular cosmic-ray transport is due to cosmic rays microscopically diffusing along the meandering magnetic field dominated by 2D turbulence because of gyroresonant interactions with slab turbulence. However, turbulence in the solar wind is intermittent and it has been suggested that intermittent turbulence might be responsible for the observation of 'dropout' events in solar energetic particle fluxes on small scales.more » In a previous paper le Roux et al. suggested, using NLGC theory as a basis, that if gyro-scale slab turbulence is intermittent, large-scale perpendicular cosmic-ray transport in weak uniform 2D turbulence will be superdiffusive or subdiffusive depending on the statistical characteristics of the intermittent slab turbulence. In this paper we expand and refine our previous work further by investigating how both parallel and perpendicular transport are affected by intermittent slab turbulence for weak as well as strong uniform 2D turbulence. The main new finding is that both parallel and perpendicular transport are the net effect of an interplay between diffusive and nondiffusive (superdiffusive or subdiffusive) transport effects as a consequence of this intermittency.« less

Preliminary Diffusive Clearance of Silicon Nanopore Membranes in a Parallel Plate Configuration for Renal Replacement Therapy

PubMed Central

Kim, Steven; Heller, James; Iqbal, Zohora; Kant, Rishi; Kim, Eun Jung; Durack, Jeremy; Saeed, Maythem; Do, Loi; Hetts, Steven; Wilson, Mark; Brakeman, Paul; Fissell, William H.; Roy, Shuvo

2015-01-01

Silicon nanopore membranes (SNM) with compact geometry and uniform pore size distribution have demonstrated a remarkable capacity for hemofiltration. These advantages could potentially be used for hemodialysis. Here we present an initial evaluation of the SNM’s mechanical robustness, diffusive clearance, and hemocompatibility in a parallel plate configuration. Mechanical robustness of the SNM was demonstrated by exposing membranes to high flows (200ml/min) and pressures (1,448mmHg). Diffusive clearance was performed in an albumin solution and whole blood with blood and dialysate flow rates of 25ml/min. Hemocompatibility was evaluated using scanning electron microscopy and immunohistochemistry after 4-hours in an extra-corporeal porcine model. The pressure drop across the flow cell was 4.6mmHg at 200ml/min. Mechanical testing showed that SNM could withstand up to 775.7mmHg without fracture. Urea clearance did not show an appreciable decline in blood versus albumin solution. Extra-corporeal studies showed blood was successfully driven via the arterial-venous pressure differential without thrombus formation. Bare silicon showed increased cell adhesion with a 4.1 fold increase and 1.8 fold increase over polyethylene-glycol (PEG)-coated surfaces for tissue plasminogen factor (t-PA) and platelet adhesion (CD-41), respectively. These initial results warrant further design and development of a fully scaled SNM-based parallel plate dialyzer for renal replacement therapy. PMID:26692401

Lattice Boltzmann approach for complex nonequilibrium flows.

PubMed

Montessori, A; Prestininzi, P; La Rocca, M; Succi, S

2015-10-01

We present a lattice Boltzmann realization of Grad's extended hydrodynamic approach to nonequilibrium flows. This is achieved by using higher-order isotropic lattices coupled with a higher-order regularization procedure. The method is assessed for flow across parallel plates and three-dimensional flows in porous media, showing excellent agreement of the mass flow with analytical and numerical solutions of the Boltzmann equation across the full range of Knudsen numbers, from the hydrodynamic regime to ballistic motion.

Modeling snow-crystal growth: a three-dimensional mesoscopic approach.

PubMed

Gravner, Janko; Griffeath, David

2009-01-01

We introduce a three-dimensional, computationally feasible, mesoscopic model for snow-crystal growth, based on diffusion of vapor, anisotropic attachment, and a boundary layer. Several case studies are presented that faithfully replicate most observed snow-crystal morphology, an unusual achievement for a mathematical model. In particular, many of the most striking physical specimens feature both facets and branches, and our model provides an explanation for this phenomenon. We also duplicate many other observed traits, including ridges, ribs, sandwich plates, and hollow columns, as well as various dynamic instabilities. The concordance of observed phenomena suggests that the ingredients in our model are the most important ones in the development of physical snow crystals.

THz wavefront manipulation based on metal waveguides

NASA Astrophysics Data System (ADS)

Wu, Mengru; Lang, Tingting; Shen, Changyu; Shi, Guohua; Han, Zhanghua

2018-07-01

In this paper, two waveguiding structures for arbitrary wavefront manipulation in the terahertz spectral region were proposed, designed and characterized. The first structure consists of parallel stack copper plates forming an array of parallel-plate waveguides (PPWGs). The second structure is three-dimensional metal rectangular waveguides array. The phase delay of the input wave after passing through the waveguide array is mainly determined by the effective index of the waveguides. Therefore, the waveguide array can be engineered using different core width distribution to generate any desired light beam. Examples, working at the frequency of 0.3 THz show that good focusing phenomenon with different focus lengths and spot sizes were observed, as well as arbitrarily tilted propagation of incident plane waves. The structure introduces a new method to perform wavefront manipulation, and can be utilized in many important applications in terahertz imaging and communication systems.

Impact of current speed on mass flux to a model flexible seagrass blade

NASA Astrophysics Data System (ADS)

Lei, Jiarui; Nepf, Heidi

2016-07-01

Seagrass and other freshwater macrophytes can acquire nutrients from surrounding water through their blades. This flux may depend on the current speed (U), which can influence both the posture of flexible blades (reconfiguration) and the thickness of the flux-limiting diffusive layer. The impact of current speed (U) on mass flux to flexible blades of model seagrass was studied through a combination of laboratory flume experiments, numerical modeling and theory. Model seagrass blades were constructed from low-density polyethylene (LDPE), and 1, 2-dichlorobenzene was used as a tracer chemical. The tracer mass accumulation in the blades was measured at different unidirectional current speeds. A numerical model was used to estimate the transfer velocity (K) by fitting the measured mass uptake to a one-dimensional diffusion model. The measured transfer velocity was compared to predictions based on laminar and turbulent boundary layers developing over a flat plate parallel to flow, for which K∝U0.5 and ∝U, respectively. The degree of blade reconfiguration depended on the dimensionless Cauchy number, Ca, which is a function of both the blade stiffness and flow velocity. For large Ca, the majority of the blade was parallel to the flow, and the measured transfer velocity agreed with laminar boundary layer theory, K∝U0.5. For small Ca, the model blades remained upright, and the flux to the blade was diminished relative to the flat-plate model. A meadow-scale analysis suggests that the mass exchange at the blade scale may control the uptake at the meadow scale.

On a model of three-dimensional bursting and its parallel implementation

NASA Astrophysics Data System (ADS)

Tabik, S.; Romero, L. F.; Garzón, E. M.; Ramos, J. I.

2008-04-01

A mathematical model for the simulation of three-dimensional bursting phenomena and its parallel implementation are presented. The model consists of four nonlinearly coupled partial differential equations that include fast and slow variables, and exhibits bursting in the absence of diffusion. The differential equations have been discretized by means of a second-order accurate in both space and time, linearly-implicit finite difference method in equally-spaced grids. The resulting system of linear algebraic equations at each time level has been solved by means of the Preconditioned Conjugate Gradient (PCG) method. Three different parallel implementations of the proposed mathematical model have been developed; two of these implementations, i.e., the MPI and the PETSc codes, are based on a message passing paradigm, while the third one, i.e., the OpenMP code, is based on a shared space address paradigm. These three implementations are evaluated on two current high performance parallel architectures, i.e., a dual-processor cluster and a Shared Distributed Memory (SDM) system. A novel representation of the results that emphasizes the most relevant factors that affect the performance of the paralled implementations, is proposed. The comparative analysis of the computational results shows that the MPI and the OpenMP implementations are about twice more efficient than the PETSc code on the SDM system. It is also shown that, for the conditions reported here, the nonlinear dynamics of the three-dimensional bursting phenomena exhibits three stages characterized by asynchronous, synchronous and then asynchronous oscillations, before a quiescent state is reached. It is also shown that the fast system reaches steady state in much less time than the slow variables.

Salinity transfer in double diffusive convection bounded by two parallel plates

NASA Astrophysics Data System (ADS)

Yang, Yantao; van der Poel, Erwin P.; Ostilla-Monico, Rodolfo; Sun, Chao; Verzicco, Roberto; Grossmann, Siegfried; Lohse, Detlef

2014-11-01

The double diffusive convection (DDC) is the convection flow with the fluid density affected by two different components. In this study we numerically investigate DDC between two parallel plates with no-slip boundary conditions. The top plate has higher salinity and temperature than the lower one. Thus the flow is driven by the salinity difference and stabilised by the temperature difference. Our simulations are compared with the experiments by Hage and Tilgner (Phys. Fluids 22, 076603 (2010)) for several sets of parameters. Reasonable agreement is achieved for the salinity flux and its dependence on the salinity Rayleigh number. For all parameters considered, salt fingers emerge and extend through the entire domain height. The thermal Rayleigh number shows minor influence on the salinity flux although it does affect the Reynolds number. We apply the Grossmann-Lohse theory for Rayleigh-Bénard flow to the current problem without introducing any new coefficients. The theory successfully predicts the salinity flux with respect to the scaling for both the numerical and experimental results.

Control of the pattern of perithecium development in Sordaria fimicola on agar medium.

PubMed

Pollock, R T

1975-06-01

In a Sordaria fimicola (Rob.) Ces. and de Not. colony grown on agar medium in a petri plate, perithecia developed in a narrow band around the plate edge after the colony margin reached the edge. Physical wounding of the colony carried out shortly before or during the time perithecia were developing around the plate edge stimulated perithecium development in the wound area. Diffusion barriers were created by cutting small trenches in the agar parallel to the plate edge. The trenches were made at several different positions between the plate center and edge using cultures of several different ages, and the resultant distribution of perithecia along the trench edges suggested that the colony center and periphery produce diffusible inhibitors of perithecium development. These inhibitors may be responsible, in part, for the observed pattern of perithecium development in the colony.

Efficient implementation of parallel three-dimensional FFT on clusters of PCs

NASA Astrophysics Data System (ADS)

Takahashi, Daisuke

2003-05-01

In this paper, we propose a high-performance parallel three-dimensional fast Fourier transform (FFT) algorithm on clusters of PCs. The three-dimensional FFT algorithm can be altered into a block three-dimensional FFT algorithm to reduce the number of cache misses. We show that the block three-dimensional FFT algorithm improves performance by utilizing the cache memory effectively. We use the block three-dimensional FFT algorithm to implement the parallel three-dimensional FFT algorithm. We succeeded in obtaining performance of over 1.3 GFLOPS on an 8-node dual Pentium III 1 GHz PC SMP cluster.

Cell growth and differentiation on feeder layers is predicted to be influenced by bioreactor geometry.

PubMed

Peng, C A; Palsson, B Ø

1996-06-05

Tissue function is comprised of a complex interplay between biological and physicochemical rate processes. The design of bioreactors for tissue engineering must account for these processes simultaneously in order to obtain a bioreactor that provides a uniform environment for tissue growth and development. In the present study we consider the effects of fluid flow and mass transfer on the growth of a tissue in a parallel-plate bioreactor configuration. The parenchymal cells grow on a preformed stromal (feeder) layer that secretes a growth factor that stimulates parenchymal stem cell replication and differentiation. The biological dynamics are described by a unilineage model that describes the replication and differentiation of the tissue stem cell. The physicochemical rates are described by the Navier-Stokes and convective-diffusion equations. The model equations are solved by a finite element method. Two dimensionless groups govern the behavior of the solution. One is the Graetz number (Gz) that describes the relative rates of convection and diffusion, and the other a new dimensionless ratio (designated by P) that describes the interplay of the growth factor production, diffusion, and stimulation. Four geometries (slab, gondola, diamond, and radial shapes) for the parallel-plate bioreactor are analyzed. The uniformity of cell growth is measured by a two-dimensional coefficient of variance. The concentration distribution of the stroma-derived growth factor was computed first based on fluid flow and bioreactor geometry. Then the concomitant cell density distribution was obtained by integrating the calculated growth factor concentration with the parenchymal cell growth and unilineage differentiation process. The spatiotemporal cell growth patterns in four different bioreactor configurations were investigated under a variety of combinations of Gz (10(-1), 10(0), and 10(1)) and P(10(-2), 10(-1), 10(0), 10(1), and 10(2)). The results indicate high cell density and uniformity can be achieved for parameter values of P = 0.01, ..., 0.1 and Gz = 0.1, ..., 1.0. Among the four geometries investigated the radial-flow-type bioreactor provides the most uniform environment in which parenchymal cells can grow and differentiate ex vivo due to the absence of walls that are parallel to the flow paths creating slow flowing regions.

A parallel reaction-transport model applied to cement hydration and microstructure development

NASA Astrophysics Data System (ADS)

Bullard, Jeffrey W.; Enjolras, Edith; George, William L.; Satterfield, Steven G.; Terrill, Judith E.

2010-03-01

A recently described stochastic reaction-transport model on three-dimensional lattices is parallelized and is used to simulate the time-dependent structural and chemical evolution in multicomponent reactive systems. The model, called HydratiCA, uses probabilistic rules to simulate the kinetics of diffusion, homogeneous reactions and heterogeneous phenomena such as solid nucleation, growth and dissolution in complex three-dimensional systems. The algorithms require information only from each lattice site and its immediate neighbors, and this localization enables the parallelized model to exhibit near-linear scaling up to several hundred processors. Although applicable to a wide range of material systems, including sedimentary rock beds, reacting colloids and biochemical systems, validation is performed here on two minerals that are commonly found in Portland cement paste, calcium hydroxide and ettringite, by comparing their simulated dissolution or precipitation rates far from equilibrium to standard rate equations, and also by comparing simulated equilibrium states to thermodynamic calculations, as a function of temperature and pH. Finally, we demonstrate how HydratiCA can be used to investigate microstructure characteristics, such as spatial correlations between different condensed phases, in more complex microstructures.

Clustering on Magnesium Surfaces - Formation and Diffusion Energies.

PubMed

Chu, Haijian; Huang, Hanchen; Wang, Jian

2017-07-12

The formation and diffusion energies of atomic clusters on Mg surfaces determine the surface roughness and formation of faulted structure, which in turn affect the mechanical deformation of Mg. This paper reports first principles density function theory (DFT) based quantum mechanics calculation results of atomic clustering on the low energy surfaces {0001} and [Formula: see text]. In parallel, molecular statics calculations serve to test the validity of two interatomic potentials and to extend the scope of the DFT studies. On a {0001} surface, a compact cluster consisting of few than three atoms energetically prefers a face-centered-cubic stacking, to serve as a nucleus of stacking fault. On a [Formula: see text], clusters of any size always prefer hexagonal-close-packed stacking. Adatom diffusion on surface [Formula: see text] is high anisotropic while isotropic on surface (0001). Three-dimensional Ehrlich-Schwoebel barriers converge as the step height is three atomic layers or thicker. Adatom diffusion along steps is via hopping mechanism, and that down steps is via exchange mechanism.

Computational investigation of longitudinal diffusion, eddy dispersion, and trans-particle mass transfer in bulk, random packings of core-shell particles with varied shell thickness and shell diffusion coefficient.

PubMed

Daneyko, Anton; Hlushkou, Dzmitry; Baranau, Vasili; Khirevich, Siarhei; Seidel-Morgenstern, Andreas; Tallarek, Ulrich

2015-08-14

In recent years, chromatographic columns packed with core-shell particles have been widely used for efficient and fast separations at comparatively low operating pressure. However, the influence of the porous shell properties on the mass transfer kinetics in core-shell packings is still not fully understood. We report on results obtained with a modeling approach to simulate three-dimensional advective-diffusive transport in bulk random packings of monosized core-shell particles, covering a range of reduced mobile phase flow velocities from 0.5 up to 1000. The impact of the effective diffusivity of analyte molecules in the porous shell and the shell thickness on the resulting plate height was investigated. An extension of Giddings' theory of coupled eddy dispersion to account for retention of analyte molecules due to stagnant regions in porous shells with zero mobile phase flow velocity is presented. The plate height equation involving a modified eddy dispersion term excellently describes simulated data obtained for particle-packings with varied shell thickness and shell diffusion coefficient. It is confirmed that the model of trans-particle mass transfer resistance of core-shell particles by Kaczmarski and Guiochon [42] is applicable up to a constant factor. We analyze individual contributions to the plate height from different mass transfer mechanisms in dependence of the shell parameters. The simulations demonstrate that a reduction of plate height in packings of core-shell relative to fully porous particles arises mainly due to reduced trans-particle mass transfer resistance and transchannel eddy dispersion. Copyright © 2015 Elsevier B.V. All rights reserved.

Trench-parallel flow beneath the nazca plate from seismic anisotropy.

PubMed

Russo, R M; Silver, P G

1994-02-25

Shear-wave splitting of S and SKS phases reveals the anisotropy and strain field of the mantle beneath the subducting Nazca plate, Cocos plate, and the Caribbean region. These observations can be used to test models of mantle flow. Two-dimensional entrained mantle flow beneath the subducting Nazca slab is not consistent with the data. Rather, there is evidence for horizontal trench-parallel flow in the mantle beneath the Nazca plate along much of the Andean subduction zone. Trench-parallel flow is attributale utable to retrograde motion of the slab, the decoupling of the slab and underlying mantle, and a partial barrier to flow at depth, resulting in lateral mantle flow beneath the slab. Such flow facilitates the transfer of material from the shrinking mantle reservoir beneath the Pacific basin to the growing mantle reservoir beneath the Atlantic basin. Trenchparallel flow may explain the eastward motions of the Caribbean and Scotia sea plates, the anomalously shallow bathymetry of the eastern Nazca plate, the long-wavelength geoid high over western South America, and it may contribute to the high elevation and intense deformation of the central Andes.

Parallel SOR methods with a parabolic-diffusion acceleration technique for solving an unstructured-grid Poisson equation on 3D arbitrary geometries

NASA Astrophysics Data System (ADS)

Zapata, M. A. Uh; Van Bang, D. Pham; Nguyen, K. D.

2016-05-01

This paper presents a parallel algorithm for the finite-volume discretisation of the Poisson equation on three-dimensional arbitrary geometries. The proposed method is formulated by using a 2D horizontal block domain decomposition and interprocessor data communication techniques with message passing interface. The horizontal unstructured-grid cells are reordered according to the neighbouring relations and decomposed into blocks using a load-balanced distribution to give all processors an equal amount of elements. In this algorithm, two parallel successive over-relaxation methods are presented: a multi-colour ordering technique for unstructured grids based on distributed memory and a block method using reordering index following similar ideas of the partitioning for structured grids. In all cases, the parallel algorithms are implemented with a combination of an acceleration iterative solver. This solver is based on a parabolic-diffusion equation introduced to obtain faster solutions of the linear systems arising from the discretisation. Numerical results are given to evaluate the performances of the methods showing speedups better than linear.

Couette flow of an incompressible fluid in a porous channel with mass transfer

NASA Astrophysics Data System (ADS)

Niranjana, N.; Vidhya, M.; Govindarajan, A.

2018-04-01

The present discussion deals with the study of couette flow through a porous medium of a viscous incompressible fluid between two infinite horizontal parallel porous flat plates with heat and mass transfer. The stationary plate and the plate in uniform motion are subjected to transverse sinusoidal injection and uniform suction of the fluid. Due to this type of injection velocity, the flow becomes three dimensional. The analytical solutions of the nonlinear partial differential equations of this problem are obtained by using perturbation technique. Expressions for the velocity, temperature fields and the rate of heat and mass transfers are obtained. Effects of the following parameters Schmidt number (Sc), Modified Grashof number (Gm) on the velocity, temperature and concentration fields are obtained numerically and depicted through graphs. The rate of heat and mass transfer are also analyzed.

Nonlinear parallel momentum transport in strong electrostatic turbulence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Lu, E-mail: luwang@hust.edu.cn; Wen, Tiliang; Diamond, P. H.

2015-05-15

Most existing theoretical studies of momentum transport focus on calculating the Reynolds stress based on quasilinear theory, without considering the nonlinear momentum flux-〈v{sup ~}{sub r}n{sup ~}u{sup ~}{sub ∥}〉. However, a recent experiment on TORPEX found that the nonlinear toroidal momentum flux induced by blobs makes a significant contribution as compared to the Reynolds stress [Labit et al., Phys. Plasmas 18, 032308 (2011)]. In this work, the nonlinear parallel momentum flux in strong electrostatic turbulence is calculated by using a three dimensional Hasegawa-Mima equation, which is relevant for tokamak edge turbulence. It is shown that the nonlinear diffusivity is smaller thanmore » the quasilinear diffusivity from Reynolds stress. However, the leading order nonlinear residual stress can be comparable to the quasilinear residual stress, and so may be important to intrinsic rotation in tokamak edge plasmas. A key difference from the quasilinear residual stress is that parallel fluctuation spectrum asymmetry is not required for nonlinear residual stress.« less

Three-Dimensional Numerical Modeling of Crustal Growth at Active Continental Margins

NASA Astrophysics Data System (ADS)

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 the finger-like plumes. We demonstrate the potential applicability of our model to clustering of arc magmatism in several subduction zones, such as Baja California (Ramos-Velázquez et al., Revista Mexicana de Ciencias Geológicas,2008), North Island of New Zealand (Booden et al., J. Volcanol. Geotherm. Res., 2010), Northeast Japan (Kimura and Yoshida,Journal of Petrology, 2006); Ecuador (Schütte et al., Tectonophysics,2010) and Lesser Antilles (Labanieh et al., EPSL,2010).

A variable-order laminated plate theory based on the variational-asymptotical method

NASA Technical Reports Server (NTRS)

Lee, Bok W.; Sutyrin, Vladislav G.; Hodges, Dewey H.

1993-01-01

The variational-asymptotical method is a mathematical technique by which the three-dimensional analysis of laminated plate deformation can be split into a linear, one-dimensional, through-the-thickness analysis and a nonlinear, two-dimensional, plate analysis. The elastic constants used in the plate analysis are obtained from the through-the-thickness analysis, along with approximate, closed-form three-dimensional distributions of displacement, strain, and stress. In this paper, a theory based on this technique is developed which is capable of approximating three-dimensional elasticity to any accuracy desired. The asymptotical method allows for the approximation of the through-the-thickness behavior in terms of the eigenfunctions of a certain Sturm-Liouville problem associated with the thickness coordinate. These eigenfunctions contain all the necessary information about the nonhomogeneities along the thickness coordinate of the plate and thus possess the appropriate discontinuities in the derivatives of displacement. The theory is presented in this paper along with numerical results for the eigenfunctions of various laminated plates.

Aeroelastic Flutter Behavior of a Cantilever and Elastically Mounted Plate within a Nozzle-Diffuser Geometry

NASA Astrophysics Data System (ADS)

Tosi, Luis Phillipe; Colonius, Tim; Lee, Hyeong Jae; Sherrit, Stewart; Jet Propulsion Laboratory Collaboration; California Institute of Technology Collaboration

2016-11-01

Aeroelastic flutter arises when the motion of a structure and its surrounding flowing fluid are coupled in a constructive manner, causing large amplitudes of vibration in the immersed solid. A cantilevered beam in axial flow within a nozzle-diffuser geometry exhibits interesting resonance behavior that presents good prospects for internal flow energy harvesting. Different modes can be excited as a function of throat velocity, nozzle geometry, fluid and cantilever material parameters. Similar behavior has been also observed in elastically mounted rigid plates, enabling new designs for such devices. This work explores the relationship between the aeroelastic flutter instability boundaries and relevant non-dimensional parameters via experiments, numerical, and stability analyses. Parameters explored consist of a non-dimensional stiffness, a non-dimensional mass, non-dimensional throat size, and Reynolds number. A map of the system response in this parameter space may serve as a guide to future work concerning possible electrical output and failure prediction in harvesting devices.

Two-dimensional numerical simulation of a Stirling engine heat exchanger

NASA Technical Reports Server (NTRS)

Ibrahim, Mounir; Tew, Roy C.; Dudenhoefer, James E.

1989-01-01

The first phase of an effort to develop multidimensional models of Stirling engine components is described. The ultimate goal is to model an entire engine working space. Parallel plate and tubular heat exchanger models are described, with emphasis on the central part of the channel (i.e., ignoring hydrodynamic and thermal end effects). The model assumes laminar, incompressible flow with constant thermophysical properties. In addition, a constant axial temperature gradient is imposed. The governing equations describing the model have been solved using the Crack-Nicloson finite-difference scheme. Model predictions are compared with analytical solutions for oscillating/reversing flow and heat transfer in order to check numerical accuracy. Excellent agreement is obtained for flow both in circular tubes and between parallel plates. The computational heat transfer results are in good agreement with the analytical heat transfer results for parallel plates.

An efficient high-frequency analysis of modal reflection and transmission coefficients for a class of waveguide discontinuities

NASA Technical Reports Server (NTRS)

Pathak, P. H.; Altintas, A.

1988-01-01

A high-frequency analysis of electromagnetic modal reflection and transmission coefficients is presented for waveguide discontinuities formed by joining different waveguide sections. The analysis uses an extended version of the concept of geometrical theory of diffraction based equivalent edge currents in conjunction with the reciprocity theorem to describe interior scattering effects. If the waveguide modes and their associated modal rays can be found explicitly, general two- and three-dimensional waveguide geometries can be analyzed. Expressions are developed for two-dimensional reflection and transmission coefficients. Numerical results are given for a flanged, semi-infinite parallel plate waveguide and for the junction between two linearly tapered waveguides.

Superfocusing terahertz waves below lambda/250 using plasmonic parallel-plate waveguides.

PubMed

Zhan, Hui; Mendis, Rajind; Mittleman, Daniel M

2010-04-26

We experimentally demonstrate complete two-dimensional (2-D) confinement of terahertz (THz) energy in finite-width parallel-plate waveguides, defying conventional wisdom in the century-old field of microwave waveguide technology. We find that the degree of energy confinement increases exponentially with decreasing plate separation. We propose that this 2-D confinement is mediated by the mutual coupling of plasmonic edge modes, analogous to that observed in slot waveguides at optical wavelengths. By adiabatically tapering the width and the separation, we focus THz waves down to a size of 10 microm (approximately lambda/260) by 18 microm ( approximately lambda/145), which corresponds to a mode area of only 2.6 x 10(-5) lambda(2).

Diffusion Tractography of the Entire Left Ventricle by Using Free-breathing Accelerated Simultaneous Multisection Imaging

PubMed Central

Reese, Timothy G.; Jackowski, Marcel P.; Cauley, Stephen F.; Setsompop, Kawin; Bhat, Himanshu; Sosnovik, David E.

2017-01-01

Purpose To develop a clinically feasible whole-heart free-breathing diffusion-tensor (DT) magnetic resonance (MR) imaging approach with an imaging time of approximately 15 minutes to enable three-dimensional (3D) tractography. Materials and Methods The study was compliant with HIPAA and the institutional review board and required written consent from the participants. DT imaging was performed in seven healthy volunteers and three patients with pulmonary hypertension by using a stimulated echo sequence. Twelve contiguous short-axis sections and six four-chamber sections that covered the entire left ventricle were acquired by using simultaneous multisection (SMS) excitation with a blipped-controlled aliasing in parallel imaging readout. Rate 2 and rate 3 SMS excitation was defined as two and three times accelerated in the section axis, respectively. Breath-hold and free-breathing images with and without SMS acceleration were acquired. Diffusion-encoding directions were acquired sequentially, spatiotemporally registered, and retrospectively selected by using an entropy-based approach. Myofiber helix angle, mean diffusivity, fractional anisotropy, and 3D tractograms were analyzed by using paired t tests and analysis of variance. Results No significant differences (P > .63) were seen between breath-hold rate 3 SMS and free-breathing rate 2 SMS excitation in transmural myofiber helix angle, mean diffusivity (mean ± standard deviation, [0.89 ± 0.09] × 10−3 mm2/sec vs [0.9 ± 0.09] × 10−3 mm2/sec), or fractional anisotropy (0.43 ± 0.05 vs 0.42 ± 0.06). Three-dimensional tractograms of the left ventricle with no SMS and rate 2 and rate 3 SMS excitation were qualitatively similar. Conclusion Free-breathing DT imaging of the entire human heart can be performed in approximately 15 minutes without section gaps by using SMS excitation with a blipped-controlled aliasing in parallel imaging readout, followed by spatiotemporal registration and entropy-based retrospective image selection. This method may lead to clinical translation of whole-heart DT imaging, enabling broad application in patients with cardiac disease. © RSNA, 2016 Online supplemental material is available for this article. PMID:27681278

Diffusion Tractography of the Entire Left Ventricle by Using Free-breathing Accelerated Simultaneous Multisection Imaging.

PubMed

Mekkaoui, Choukri; Reese, Timothy G; Jackowski, Marcel P; Cauley, Stephen F; Setsompop, Kawin; Bhat, Himanshu; Sosnovik, David E

2017-03-01

Purpose To develop a clinically feasible whole-heart free-breathing diffusion-tensor (DT) magnetic resonance (MR) imaging approach with an imaging time of approximately 15 minutes to enable three-dimensional (3D) tractography. Materials and Methods The study was compliant with HIPAA and the institutional review board and required written consent from the participants. DT imaging was performed in seven healthy volunteers and three patients with pulmonary hypertension by using a stimulated echo sequence. Twelve contiguous short-axis sections and six four-chamber sections that covered the entire left ventricle were acquired by using simultaneous multisection (SMS) excitation with a blipped-controlled aliasing in parallel imaging readout. Rate 2 and rate 3 SMS excitation was defined as two and three times accelerated in the section axis, respectively. Breath-hold and free-breathing images with and without SMS acceleration were acquired. Diffusion-encoding directions were acquired sequentially, spatiotemporally registered, and retrospectively selected by using an entropy-based approach. Myofiber helix angle, mean diffusivity, fractional anisotropy, and 3D tractograms were analyzed by using paired t tests and analysis of variance. Results No significant differences (P > .63) were seen between breath-hold rate 3 SMS and free-breathing rate 2 SMS excitation in transmural myofiber helix angle, mean diffusivity (mean ± standard deviation, [0.89 ± 0.09] × 10 -3 mm 2 /sec vs [0.9 ± 0.09] × 10 -3 mm 2 /sec), or fractional anisotropy (0.43 ± 0.05 vs 0.42 ± 0.06). Three-dimensional tractograms of the left ventricle with no SMS and rate 2 and rate 3 SMS excitation were qualitatively similar. Conclusion Free-breathing DT imaging of the entire human heart can be performed in approximately 15 minutes without section gaps by using SMS excitation with a blipped-controlled aliasing in parallel imaging readout, followed by spatiotemporal registration and entropy-based retrospective image selection. This method may lead to clinical translation of whole-heart DT imaging, enabling broad application in patients with cardiac disease. © RSNA, 2016 Online supplemental material is available for this article.

On the strain energy of laminated composite plates

NASA Technical Reports Server (NTRS)

Atilgan, Ali R.; Hodges, Dewey H.

1991-01-01

The present effort to obtain the asymptotically correct form of the strain energy in inhomogeneous laminated composite plates proceeds from the geometrically nonlinear elastic theory-based three-dimensional strain energy by decomposing the nonlinear three-dimensional problem into a linear, through-the-thickness analysis and a nonlinear, two-dimensional analysis analyzing plate formation. Attention is given to the case in which each lamina exhibits material symmetry about its middle surface, deriving closed-form analytical expressions for the plate elastic constants and the displacement and strain distributions through the plate's thickness. Despite the simplicity of the plate strain energy's form, there are no restrictions on the magnitudes of displacement and rotation measures.

Reconnection in Three Dimensions

NASA Technical Reports Server (NTRS)

Hesse, Michael

1999-01-01

Analyzing the qualitative three-dimensional magnetic structure of a plasmoid, we were led to reconsider the concept of magnetic reconnection from a general point of view. The properties of relatively simple magnetic field models provide a strong preference for one of two definitions of magnetic reconnection that exist in the literature. Any concept of magnetic reconnection defined in terms of magnetic topology seems naturally restricted to cases where the magnetic field vanishes somewhere in the nonideal (diffusion) region. The main part of this paper is concerned with magnetic reconnection in nonvanishing magnetic fields (finite-B reconnection), which has attracted less attention in the past. We show that the electric field component parallel to the magnetic field plays a crucial physical role in finite-B reconnection, and we present two theorems involving the former. The first states a necessary and sufficient condition on the parallel electric field for global reconnection to occur. Here the term "global" means the generic case where the breakdown of magnetic connection occurs for plasma elements that stay outside the nonideal region. The second theorem relates the change of magnetic helicity to the parallel electric field for cases where the electric field vanishes at large distances. That these results provide new insight into three-dimensional reconnection processes is illustrated in terms of the plasmoid configuration, which was our starting point.

Short-time dynamics of monomers and dimers in quasi-two-dimensional colloidal mixtures.

PubMed

Sarmiento-Gómez, Erick; Villanueva-Valencia, José Ramón; Herrera-Velarde, Salvador; Ruiz-Santoyo, José Arturo; Santana-Solano, Jesús; Arauz-Lara, José Luis; Castañeda-Priego, Ramón

2016-07-01

We report on the short-time dynamics in colloidal mixtures made up of monomers and dimers highly confined between two glass plates. At low concentrations, the experimental measurements of colloidal motion agree well with the solution of the Navier-Stokes equation at low Reynolds numbers; the latter takes into account the increase in the drag force on a colloidal particle due to wall-particle hydrodynamic forces. More importantly, we find that the ratio of the short-time diffusion coefficient of the monomer and that of the center of mass of the dimmer is almost independent of both the dimer molar fraction, x_{d}, and the total packing fraction, ϕ, up to ϕ≈0.5. At higher concentrations, this ratio displays a small but systematic increase. A similar physical scenario is observed for the ratio between the parallel and the perpendicular components of the short-time diffusion coefficients of the dimer. This dynamical behavior is corroborated by means of molecular dynamics computer simulations that include explicitly the particle-particle hydrodynamic forces induced by the solvent. Our results suggest that the effects of colloid-colloid hydrodynamic interactions on the short-time diffusion coefficients are almost identical and factorable in both species.

Massively Parallel Simulations of Diffusion in Dense Polymeric Structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faulon, Jean-Loup, Wilcox, R.T.

1997-11-01

An original computational technique to generate close-to-equilibrium dense polymeric structures is proposed. Diffusion of small gases are studied on the equilibrated structures using massively parallel molecular dynamics simulations running on the Intel Teraflops (9216 Pentium Pro processors) and Intel Paragon(1840 processors). Compared to the current state-of-the-art equilibration methods this new technique appears to be faster by some orders of magnitude.The main advantage of the technique is that one can circumvent the bottlenecks in configuration space that inhibit relaxation in molecular dynamics simulations. The technique is based on the fact that tetravalent atoms (such as carbon and silicon) fit in themore » center of a regular tetrahedron and that regular tetrahedrons can be used to mesh the three-dimensional space. Thus, the problem of polymer equilibration described by continuous equations in molecular dynamics is reduced to a discrete problem where solutions are approximated by simple algorithms. Practical modeling applications include the constructing of butyl rubber and ethylene-propylene-dimer-monomer (EPDM) models for oxygen and water diffusion calculations. Butyl and EPDM are used in O-ring systems and serve as sealing joints in many manufactured objects. Diffusion coefficients of small gases have been measured experimentally on both polymeric systems, and in general the diffusion coefficients in EPDM are an order of magnitude larger than in butyl. In order to better understand the diffusion phenomena, 10, 000 atoms models were generated and equilibrated for butyl and EPDM. The models were submitted to a massively parallel molecular dynamics simulation to monitor the trajectories of the diffusing species.« less

High loading uranium fuel plate

DOEpatents

Wiencek, Thomas C.; Domagala, Robert F.; Thresh, Henry R.

1990-01-01

Two embodiments of a high uranium fuel plate are disclosed which contain a meat comprising structured uranium compound confined between a pair of diffusion bonded ductile metal cladding plates uniformly covering the meat, the meat having a uniform high fuel loading comprising a content of uranium compound greater than about 45 Vol. % at a porosity not greater than about 10 Vol. %. In a first embodiment, the meat is a plurality of parallel wires of uranium compound. In a second embodiment, the meat is a dispersion compact containing uranium compound. The fuel plates are fabricated by a hot isostatic pressing process.

A direct numerical method for predicting concentration profiles in a turbulent boundary layer over a flat plate. M.S. Thesis

NASA Technical Reports Server (NTRS)

Dow, J. W.

1972-01-01

A numerical solution of the turbulent mass transport equation utilizing the concept of eddy diffusivity is presented as an efficient method of investigating turbulent mass transport in boundary layer type flows. A FORTRAN computer program is used to study the two-dimensional diffusion of ammonia, from a line source on the surface, into a turbulent boundary layer over a flat plate. The results of the numerical solution are compared with experimental data to verify the results of the solution. Several other solutions to diffusion problems are presented to illustrate the versatility of the computer program and to provide some insight into the problem of mass diffusion as a whole.

Two-dimensional numerical simulation of a Stirling engine heat exchanger

NASA Technical Reports Server (NTRS)

Ibrahim, Mounir B.; Tew, Roy C.; Dudenhoefer, James E.

1989-01-01

The first phase of an effort to develop multidimensional models of Stirling engine components is described; the ultimate goal is to model an entire engine working space. More specifically, parallel plate and tubular heat exchanger models with emphasis on the central part of the channel (i.e., ignoring hydrodynamic and thermal end effects) are described. The model assumes: laminar, incompressible flow with constant thermophysical properties. In addition, a constant axial temperature gradient is imposed. The governing equations, describing the model, were solved using Crank-Nicloson finite-difference scheme. Model predictions were compared with analytical solutions for oscillating/reversing flow and heat transfer in order to check numerical accuracy. Excellent agreement was obtained for the model predictions with analytical solutions available for both flow in circular tubes and between parallel plates. Also the heat transfer computational results are in good agreement with the heat transfer analytical results for parallel plates.

Clustering on Magnesium Surfaces – Formation and Diffusion Energies

DOE PAGES

Chu, Haijian; Huang, Hanchen; Wang, Jian

2017-07-12

The formation and diffusion energies of atomic clusters on Mg surfaces determine the surface roughness and formation of faulted structure, which in turn affect the mechanical deformation of Mg. This paper reports first principles density function theory (DFT) based quantum mechanics calculation results of atomic clustering on the low energy surfaces {0001} and {more » $$\\bar{1}$$011} . In parallel, molecular statics calculations serve to test the validity of two interatomic potentials and to extend the scope of the DFT studies. On a {0001} surface, a compact cluster consisting of few than three atoms energetically prefers a face-centered-cubic stacking, to serve as a nucleus of stacking fault. On a {$$\\bar{1}$$011} , clusters of any size always prefer hexagonal-close-packed stacking. Adatom diffusion on surface {$$\\bar{1}$$011} is high anisotropic while isotropic on surface (0001). Three-dimensional Ehrlich–Schwoebel barriers converge as the step height is three atomic layers or thicker. FInally, adatom diffusion along steps is via hopping mechanism, and that down steps is via exchange mechanism.« less

Clustering on Magnesium Surfaces – Formation and Diffusion Energies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chu, Haijian; Huang, Hanchen; Wang, Jian

The formation and diffusion energies of atomic clusters on Mg surfaces determine the surface roughness and formation of faulted structure, which in turn affect the mechanical deformation of Mg. This paper reports first principles density function theory (DFT) based quantum mechanics calculation results of atomic clustering on the low energy surfaces {0001} and {more » $$\\bar{1}$$011} . In parallel, molecular statics calculations serve to test the validity of two interatomic potentials and to extend the scope of the DFT studies. On a {0001} surface, a compact cluster consisting of few than three atoms energetically prefers a face-centered-cubic stacking, to serve as a nucleus of stacking fault. On a {$$\\bar{1}$$011} , clusters of any size always prefer hexagonal-close-packed stacking. Adatom diffusion on surface {$$\\bar{1}$$011} is high anisotropic while isotropic on surface (0001). Three-dimensional Ehrlich–Schwoebel barriers converge as the step height is three atomic layers or thicker. FInally, adatom diffusion along steps is via hopping mechanism, and that down steps is via exchange mechanism.« less

Analytical investigation of third grade nanofluidic flow over a riga plate using Cattaneo-Christov model

NASA Astrophysics Data System (ADS)

Naseem, Anum; Shafiq, Anum; Zhao, Lifeng; Farooq, M. U.

2018-06-01

This article addresses third grade nanofluidic flow instigated by riga plate and Cattaneo-Christov theory is adopted to investigate thermal and mass diffusions with the incorporation of newly eminent zero nanoparticles mass flux condition. The governing system of equations is nondimensionalized through relevant similarity transformations and significatory findings are attained by using optimal homotopy analysis method. The behaviors of affecting parameters for velocity, temperature and concentration profiles are depicted graphically and also verified through three dimensional patterns for some parameters. Values of skin friction coefficient and Nusselt number with the apposite discussion have been recorded. The current results reveal that temperature and concentration profiles experience decline when thermal and concentration relaxation parameters are augmented respectively.

Diffuse Extension of the Southern Mariana Margin: Implications for Subduction Zone Infancy and Plate Tectonics

NASA Astrophysics Data System (ADS)

Martinez, F.; Stern, R. J.; Kelley, K. A.; Ohara, Y.; Sleeper, J. D.; Ribeiro, J. M.; Brounce, M. N.

2017-12-01

Opening of the southern Mariana margin takes place in contrasting modes: Extension normal to the trench forms crust that is passively accreted to a rigid Philippine Sea plate and forms along focused and broad accretion axes. Extension also occurs parallel to the trench and has split apart an Eocene-Miocene forearc terrain accreting new crust diffusely over a 150-200 km wide zone forming a pervasive volcano-tectonic fabric oriented at high angles to the trench and the backarc spreading center. Earthquake seismicity indicates that the forearc extension is active over this broad area and basement samples date young although waning volcanic activity. Diffuse formation of new oceanic crust and lithosphere is unusual; in most oceanic settings extension rapidly focuses to narrow plate boundary zones—a defining feature of plate tectonics. Diffuse crustal accretion has been inferred to occur during subduction zone infancy, however. We hypothesize that, in a near-trench extensional setting, the continual addition of water from the subducting slab creates a weak overriding hydrous lithosphere that deforms broadly. This process counteracts mantle dehydration and strengthening proposed to occur at mid-ocean ridges that may help to focus deformation and melt delivery to narrow plate boundary zones. The observations from the southern Mariana margin suggest that where lithosphere is weakened by high water content narrow seafloor spreading centers cannot form. These conditions likely prevail during subduction zone infancy, explaining the diffuse contemporaneous volcanism inferred in this setting.

A cellular automaton method to simulate the microstructure and evolution of low-enriched uranium (LEU) U-Mo/Al dispersion type fuel plates

NASA Astrophysics Data System (ADS)

Drera, Saleem S.; Hofman, Gerard L.; Kee, Robert J.; King, Jeffrey C.

2014-10-01

Low-enriched uranium (LEU) fuel plates for high power materials test reactors (MTR) are composed of nominally spherical uranium-molybdenum (U-Mo) particles within an aluminum matrix. Fresh U-Mo particles typically range between 10 and 100 μm in diameter, with particle volume fractions up to 50%. As the fuel ages, reaction-diffusion processes cause the formation and growth of interaction layers that surround the fuel particles. The growth rate depends upon the temperature and radiation environment. The cellular automaton algorithm described in this paper can synthesize realistic random fuel-particle structures and simulate the growth of the intermetallic interaction layers. Examples in the present paper pack approximately 1000 particles into three-dimensional rectangular fuel structures that are approximately 1 mm on each side. The computational approach is designed to yield synthetic microstructures consistent with images from actual fuel plates and is validated by comparison with empirical data on actual fuel plates.

Multi-Dimensional, Mesoscopic Monte Carlo Simulations of Inhomogeneous Reaction-Drift-Diffusion Systems on Graphics-Processing Units

PubMed Central

Vigelius, Matthias; Meyer, Bernd

2012-01-01

For many biological applications, a macroscopic (deterministic) treatment of reaction-drift-diffusion systems is insufficient. Instead, one has to properly handle the stochastic nature of the problem and generate true sample paths of the underlying probability distribution. Unfortunately, stochastic algorithms are computationally expensive and, in most cases, the large number of participating particles renders the relevant parameter regimes inaccessible. In an attempt to address this problem we present a genuine stochastic, multi-dimensional algorithm that solves the inhomogeneous, non-linear, drift-diffusion problem on a mesoscopic level. Our method improves on existing implementations in being multi-dimensional and handling inhomogeneous drift and diffusion. The algorithm is well suited for an implementation on data-parallel hardware architectures such as general-purpose graphics processing units (GPUs). We integrate the method into an operator-splitting approach that decouples chemical reactions from the spatial evolution. We demonstrate the validity and applicability of our algorithm with a comprehensive suite of standard test problems that also serve to quantify the numerical accuracy of the method. We provide a freely available, fully functional GPU implementation. Integration into Inchman, a user-friendly web service, that allows researchers to perform parallel simulations of reaction-drift-diffusion systems on GPU clusters is underway. PMID:22506001

Magnetospheric Multiscale Satellites Observations of Parallel Electric Fields Associated with Magnetic Reconnection

NASA Technical Reports Server (NTRS)

Ergun, R. E.; Goodrich, K. A.; Wilder, F. D.; Holmes, J. C.; Stawarz, J. E.; Eriksson, S.; Sturner, A. P.; Malaspina, D. M.; Usanova, M. E.; Torbert, R. B.;

Remote micro-encapsulation of curium-gold cermets

NASA Astrophysics Data System (ADS)

Coops, M. S.; Voegele, A. L.; Hayes, W. N.; Sisson, D. H.

1982-09-01

A technique has been developed to produce miniature, high-density capsules of curium-244 oxide contained in three concentric jackets of metallic gold or silver. The final capsules are right circular cylinders, 6.350 mm diameter by (3.18±0.05) mm long, with a minimum density of 11.0 g/cm 3. Each level of containment was soldered or brazed closed, with the outer surface free of detectable alpha contamination. Fabrication was performed in three separate small cells operated by standard master-slave manipulators. Production capsules have been stored for up to five years without indication of dimensional growth or leakage of radioactive contents. The dimensional stability of the capsules is attributed to the microporous structure of the plated-gold structure which permits helium gas resulting from alpha decay to diffuse through the capsule wall while retaining all radioactive materials.

Decoupling Principle Analysis and Development of a Parallel Three-Dimensional Force Sensor

PubMed Central

Zhao, Yanzhi; Jiao, Leihao; Weng, Dacheng; Zhang, Dan; Zheng, Rencheng

2016-01-01

In the development of the multi-dimensional force sensor, dimension coupling is the ubiquitous factor restricting the improvement of the measurement accuracy. To effectively reduce the influence of dimension coupling on the parallel multi-dimensional force sensor, a novel parallel three-dimensional force sensor is proposed using a mechanical decoupling principle, and the influence of the friction on dimension coupling is effectively reduced by making the friction rolling instead of sliding friction. In this paper, the mathematical model is established by combining with the structure model of the parallel three-dimensional force sensor, and the modeling and analysis of mechanical decoupling are carried out. The coupling degree (ε) of the designed sensor is defined and calculated, and the calculation results show that the mechanical decoupling parallel structure of the sensor possesses good decoupling performance. A prototype of the parallel three-dimensional force sensor was developed, and FEM analysis was carried out. The load calibration and data acquisition experiment system are built, and then calibration experiments were done. According to the calibration experiments, the measurement accuracy is less than 2.86% and the coupling accuracy is less than 3.02%. The experimental results show that the sensor system possesses high measuring accuracy, which provides a basis for the applied research of the parallel multi-dimensional force sensor. PMID:27649194

Convection in three dimensions with surface plates - Generation of toroidal flow

NASA Technical Reports Server (NTRS)

Gable, Carl W.; O'Connell, Richard J.; Travis, Bryan J.

1991-01-01

This work presents numerical calculations of mantle convection that incorporate some of the basic observational constraints imposed by plate tectonics. The model is three-dimensional and includes surface plates; it allows plate velocity to change dynamically according to the forces which result from convection. It is shown that plates are an effective means of introducing a toroidal component into the flow field. After initial transients the plate motion is nearly parallel to transform faults and in the direction that tends to minimize the toroidal flow field. The toroidal field decays with depth from its value at the surface; the poloidal field is relatively constant throughout the layer but falls off slightly at the top and bottom boundaries. Layered viscosity increasing with depth causes the toroidal field to decay more rapidly, effectively confining it to the upper, low-viscosity layer. The effect of viscosity layering on the poloidal field is relatively small, which is attributed to its generation by temperature variations distributed throughout the system. The generation of toroidal flow by surface plates would seem to account for the observed nearly equal energy of toroidal and poloidal fields of plate motions on the earth. A low-viscosity region in the upper mantle will cause the toroidal flow to decay significantly before reaching the lower mantle. The resulting concentration of toroidal flow in the upper mantle may result in more thorough mixing there and account for some of the geochemical and isotopic differences proposed to exist between the upper and lower mantles.

System and method for representing and manipulating three-dimensional objects on massively parallel architectures

DOEpatents

Karasick, Michael S.; Strip, David R.

1996-01-01

A parallel computing system is described that comprises a plurality of uniquely labeled, parallel processors, each processor capable of modelling a three-dimensional object that includes a plurality of vertices, faces and edges. The system comprises a front-end processor for issuing a modelling command to the parallel processors, relating to a three-dimensional object. Each parallel processor, in response to the command and through the use of its own unique label, creates a directed-edge (d-edge) data structure that uniquely relates an edge of the three-dimensional object to one face of the object. Each d-edge data structure at least includes vertex descriptions of the edge and a description of the one face. As a result, each processor, in response to the modelling command, operates upon a small component of the model and generates results, in parallel with all other processors, without the need for processor-to-processor intercommunication.

Parallel Computation and Visualization of Three-dimensional, Time-dependent, Thermal Convective Flows

NASA Technical Reports Server (NTRS)

Wang, P.; Li, P.

1998-01-01

A high-resolution numerical study on parallel systems is reported on three-dimensional, time-dependent, thermal convective flows. A parallel implentation on the finite volume method with a multigrid scheme is discussed, and a parallel visualization systemm is developed on distributed systems for visualizing the flow.

Three-dimensional charge coupled device

DOEpatents

Conder, Alan D.; Young, Bruce K. F.

1999-01-01

A monolithic three dimensional charged coupled device (3D-CCD) which utilizes the entire bulk of the semiconductor for charge generation, storage, and transfer. The 3D-CCD provides a vast improvement of current CCD architectures that use only the surface of the semiconductor substrate. The 3D-CCD is capable of developing a strong E-field throughout the depth of the semiconductor by using deep (buried) parallel (bulk) electrodes in the substrate material. Using backside illumination, the 3D-CCD architecture enables a single device to image photon energies from the visible, to the ultra-violet and soft x-ray, and out to higher energy x-rays of 30 keV and beyond. The buried or bulk electrodes are electrically connected to the surface electrodes, and an E-field parallel to the surface is established with the pixel in which the bulk electrodes are located. This E-field attracts charge to the bulk electrodes independent of depth and confines it within the pixel in which it is generated. Charge diffusion is greatly reduced because the E-field is strong due to the proximity of the bulk electrodes.

A solution procedure for behavior of thick plates on a nonlinear foundation and postbuckling behavior of long plates

NASA Technical Reports Server (NTRS)

Stein, M.; Stein, P. A.

1978-01-01

Approximate solutions for three nonlinear orthotropic plate problems are presented: (1) a thick plate attached to a pad having nonlinear material properties which, in turn, is attached to a substructure which is then deformed; (2) a long plate loaded in inplane longitudinal compression beyond its buckling load; and (3) a long plate loaded in inplane shear beyond its buckling load. For all three problems, the two dimensional plate equations are reduced to one dimensional equations in the y-direction by using a one dimensional trigonometric approximation in the x-direction. Each problem uses different trigonometric terms. Solutions are obtained using an existing algorithm for simultaneous, first order, nonlinear, ordinary differential equations subject to two point boundary conditions. Ordinary differential equations are derived to determine the variable coefficients of the trigonometric terms.

MPI-AMRVAC 2.0 for Solar and Astrophysical Applications

NASA Astrophysics Data System (ADS)

Xia, C.; Teunissen, J.; El Mellah, I.; Chané, E.; Keppens, R.

2018-02-01

We report on the development of MPI-AMRVAC version 2.0, which is an open-source framework for parallel, grid-adaptive simulations of hydrodynamic and magnetohydrodynamic (MHD) astrophysical applications. The framework now supports radial grid stretching in combination with adaptive mesh refinement (AMR). The advantages of this combined approach are demonstrated with one-dimensional, two-dimensional, and three-dimensional examples of spherically symmetric Bondi accretion, steady planar Bondi–Hoyle–Lyttleton flows, and wind accretion in supergiant X-ray binaries. Another improvement is support for the generic splitting of any background magnetic field. We present several tests relevant for solar physics applications to demonstrate the advantages of field splitting on accuracy and robustness in extremely low-plasma β environments: a static magnetic flux rope, a magnetic null-point, and magnetic reconnection in a current sheet with either uniform or anomalous resistivity. Our implementation for treating anisotropic thermal conduction in multi-dimensional MHD applications is also described, which generalizes the original slope-limited symmetric scheme from two to three dimensions. We perform ring diffusion tests that demonstrate its accuracy and robustness, and show that it prevents the unphysical thermal flux present in traditional schemes. The improved parallel scaling of the code is demonstrated with three-dimensional AMR simulations of solar coronal rain, which show satisfactory strong scaling up to 2000 cores. Other framework improvements are also reported: the modernization and reorganization into a library, the handling of automatic regression tests, the use of inline/online Doxygen documentation, and a new future-proof data format for input/output.

Coherent structures and flow topology of transitional separated-reattached flow over two and three dimensional geometrical shapes

NASA Astrophysics Data System (ADS)

Diabil, Hayder Azeez; Li, Xin Kai; Abdalla, Ibrahim Elrayah

2017-09-01

Large-scale organized motions (commonly referred to coherent structures) and flow topology of a transitional separated-reattached flow have been visualised and investigated using flow visualisation techniques. Two geometrical shapes including two-dimensional flat plate with rectangular leading edge and three-dimensional square cylinder are chosen to shed a light on the flow topology and present coherent structures of the flow over these shapes. For both geometries and in the early stage of the transition, two-dimensional Kelvin-Helmholtz rolls are formed downstream of the leading edge. They are observed to be twisting around the square cylinder while they stay flat in the case of the two-dimensional flat plate. For both geometrical shapes, the two-dimensional Kelvin-Helmholtz rolls move downstream of the leading edge and they are subjected to distortion to form three-dimensional hairpin structures. The flow topology in the flat plate is different from that in the square cylinder. For the flat plate, there is a merging process by a pairing of the Kelvin-Helmholtz rolls to form a large structure that breaks down directly into many hairpin structures. For the squire cylinder case, the Kelvin-Helmholtz roll evolves topologically to form a hairpin structure. In the squire cylinder case, the reattachment length is much shorter and a forming of the three-dimensional structures is closer to the leading edge than that in the flat plate case.

Electromagnetic Design of a Magnetically-Coupled Spatial Power Combiner

NASA Technical Reports Server (NTRS)

Bulcha, B.; Cataldo, G.; Stevenson, T. R.; U-Yen, K.; Moseley, S. H.; Wollack, E. J.

2017-01-01

The design of a two-dimensional beam-combining network employing a parallel-plate superconducting waveguide with a mono-crystalline silicon dielectric is presented. This novel beam-combining network structure employs an array of magnetically coupled antenna elements to achieve high coupling efficiency and full sampling of the intensity distribution while avoiding diffractive losses in the multi-mode region defined by the parallel-plate waveguide. These attributes enable the structures use in realizing compact far-infrared spectrometers for astrophysical and instrumentation applications. When configured with a suitable corporate-feed power-combiner, this fully sampled array can be used to realize a low-sidelobe apodized response without incurring a reduction in coupling efficiency. To control undesired reflections over a wide range of angles in the finite-sized parallel-plate waveguide region, a wideband meta-material electromagnetic absorber structure is implemented. This adiabatic structure absorbs greater than 99 of the power over the 1.7:1 operational band at angles ranging from normal (0 degree) to near parallel (180 degree) incidence. Design, simulations, and application of the device will be presented.

The transference of heat from a hot plate to an air stream

NASA Technical Reports Server (NTRS)

Elias, Franz

1931-01-01

The object of the present study was to define experimentally the field of temperature and velocity in a heated flat plate when exposed to an air stream whose direction is parallel to it, then calculate therefrom the heat transference and the friction past the flat plate, and lastly, compare the test data with the mathematical theory. To ensure comparable results, we were to actually obtain or else approximate: a) two-dimensional flow; b) constant plate temperature in the direction of the stream. To approximate the flow in two dimensions, we chose a relatively wide plate and measured the velocity and temperature in the median plane.

Ex-vessel neutron dosimetry analysis for westinghouse 4-loop XL pressurized water reactor plant using the RadTrack{sup TM} Code System with the 3D parallel discrete ordinates code RAPTOR-M3G

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, J.; Alpan, F. A.; Fischer, G.A.

2011-07-01

Traditional two-dimensional (2D)/one-dimensional (1D) SYNTHESIS methodology has been widely used to calculate fast neutron (>1.0 MeV) fluence exposure to reactor pressure vessel in the belt-line region. However, it is expected that this methodology cannot provide accurate fast neutron fluence calculation at elevations far above or below the active core region. A three-dimensional (3D) parallel discrete ordinates calculation for ex-vessel neutron dosimetry on a Westinghouse 4-Loop XL Pressurized Water Reactor has been done. It shows good agreement between the calculated results and measured results. Furthermore, the results show very different fast neutron flux values at some of the former plate locationsmore » and elevations above and below an active core than those calculated by a 2D/1D SYNTHESIS method. This indicates that for certain irregular reactor internal structures, where the fast neutron flux has a very strong local effect, it is required to use a 3D transport method to calculate accurate fast neutron exposure. (authors)« less

Direct measurement of lateral transport in membranes by using time-resolved spatial photometry.

PubMed Central

Kapitza, H G; McGregor, G; Jacobson, K A

1985-01-01

Spatially resolving light detectors allow, with proper calibration, quantitative analysis of the variations in two-dimensional intensity distributions over time. An ultrasensitive microfluorometer was assembled by using as a detector a microchannel plate-intensified video camera. The camera was interfaced with a software-based digital video analysis system to digitize, average, and process images and to directly control the timing of the experiments to minimize exposure of the specimen to light. The detector system has been characterized to allow its use as a photometer. A major application has been to perform fluorescence recovery after photobleaching measurements by using the camera in place of a photomultiplier tube (video-FRAP) with the goal of detecting possible anisotropic diffusion or convective flow. Analysis of the data on macromolecular diffusion in homogenous aqueous glycol solutions yielded diffusion constants in agreement with previous measurements. Results on lipid probe diffusion in dimyristoylphosphatidylcholine multibilayers indicated that at temperatures above the gel-to-liquid crystalline phase transition diffusion is isotropic, and analysis of video-FRAP data yielded diffusion coefficients consistent with those measured previously by using spot photobleaching. However, lipid probes in these multibilayers held just below the main phase transition temperature exhibited markedly anisotropic diffusive fluxes when the bleaching beam was positioned proximate to domain boundaries in the P beta' phase. Lipid probes and lectin receptor complexes diffused isotropically in fibroblast surface membranes with little evidence for diffusion channeled parallel to stress fibers. A second application was to trace the time evolution of cell surface reactions such as patching. The feasibility of following, on the optical scale, the growth of individual receptor clusters induced by the ligand wheat germ agglutinin was demonstrated. PMID:3858869

Direct measurement of lateral transport in membranes by using time-resolved spatial photometry.

PubMed

Kapitza, H G; McGregor, G; Jacobson, K A

1985-06-01

Spatially resolving light detectors allow, with proper calibration, quantitative analysis of the variations in two-dimensional intensity distributions over time. An ultrasensitive microfluorometer was assembled by using as a detector a microchannel plate-intensified video camera. The camera was interfaced with a software-based digital video analysis system to digitize, average, and process images and to directly control the timing of the experiments to minimize exposure of the specimen to light. The detector system has been characterized to allow its use as a photometer. A major application has been to perform fluorescence recovery after photobleaching measurements by using the camera in place of a photomultiplier tube (video-FRAP) with the goal of detecting possible anisotropic diffusion or convective flow. Analysis of the data on macromolecular diffusion in homogenous aqueous glycol solutions yielded diffusion constants in agreement with previous measurements. Results on lipid probe diffusion in dimyristoylphosphatidylcholine multibilayers indicated that at temperatures above the gel-to-liquid crystalline phase transition diffusion is isotropic, and analysis of video-FRAP data yielded diffusion coefficients consistent with those measured previously by using spot photobleaching. However, lipid probes in these multibilayers held just below the main phase transition temperature exhibited markedly anisotropic diffusive fluxes when the bleaching beam was positioned proximate to domain boundaries in the P beta' phase. Lipid probes and lectin receptor complexes diffused isotropically in fibroblast surface membranes with little evidence for diffusion channeled parallel to stress fibers. A second application was to trace the time evolution of cell surface reactions such as patching. The feasibility of following, on the optical scale, the growth of individual receptor clusters induced by the ligand wheat germ agglutinin was demonstrated.

Nonclassical models of the theory of plates and shells

NASA Astrophysics Data System (ADS)

Annin, Boris D.; Volchkov, Yuri M.

2017-11-01

Publications dealing with the study of methods of reducing a three-dimensional problem of the elasticity theory to a two-dimensional problem of the theory of plates and shells are reviewed. Two approaches are considered: the use of kinematic and force hypotheses and expansion of solutions of the three-dimensional elasticity theory in terms of the complete system of functions. Papers where a three-dimensional problem is reduced to a two-dimensional problem with the use of several approximations of each of the unknown functions (stresses and displacements) by segments of the Legendre polynomials are also reviewed.

System and method for representing and manipulating three-dimensional objects on massively parallel architectures

DOEpatents

Karasick, M.S.; Strip, D.R.

1996-01-30

A parallel computing system is described that comprises a plurality of uniquely labeled, parallel processors, each processor capable of modeling a three-dimensional object that includes a plurality of vertices, faces and edges. The system comprises a front-end processor for issuing a modeling command to the parallel processors, relating to a three-dimensional object. Each parallel processor, in response to the command and through the use of its own unique label, creates a directed-edge (d-edge) data structure that uniquely relates an edge of the three-dimensional object to one face of the object. Each d-edge data structure at least includes vertex descriptions of the edge and a description of the one face. As a result, each processor, in response to the modeling command, operates upon a small component of the model and generates results, in parallel with all other processors, without the need for processor-to-processor intercommunication. 8 figs.

On the dimensionally correct kinetic theory of turbulence for parallel propagation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaelzer, R., E-mail: rudi.gaelzer@ufrgs.br, E-mail: yoonp@umd.edu, E-mail: 007gasun@khu.ac.kr, E-mail: luiz.ziebell@ufrgs.br; Ziebell, L. F., E-mail: rudi.gaelzer@ufrgs.br, E-mail: yoonp@umd.edu, E-mail: 007gasun@khu.ac.kr, E-mail: luiz.ziebell@ufrgs.br; Yoon, P. H., E-mail: rudi.gaelzer@ufrgs.br, E-mail: yoonp@umd.edu, E-mail: 007gasun@khu.ac.kr, E-mail: luiz.ziebell@ufrgs.br

2015-03-15

Yoon and Fang [Phys. Plasmas 15, 122312 (2008)] formulated a second-order nonlinear kinetic theory that describes the turbulence propagating in directions parallel/anti-parallel to the ambient magnetic field. Their theory also includes discrete-particle effects, or the effects due to spontaneously emitted thermal fluctuations. However, terms associated with the spontaneous fluctuations in particle and wave kinetic equations in their theory contain proper dimensionality only for an artificial one-dimensional situation. The present paper extends the analysis and re-derives the dimensionally correct kinetic equations for three-dimensional case. The new formalism properly describes the effects of spontaneous fluctuations emitted in three-dimensional space, while the collectivelymore » emitted turbulence propagates predominantly in directions parallel/anti-parallel to the ambient magnetic field. As a first step, the present investigation focuses on linear wave-particle interaction terms only. A subsequent paper will include the dimensionally correct nonlinear wave-particle interaction terms.« less

Investigation of the Non-Isothermal Convective Mixing of Turbulent, Round, Wall Jets

NASA Astrophysics Data System (ADS)

Kristo, Paul; Kimber, Mark

2017-11-01

The wall jet has become a paradigm for geometrically bounded flows due to the intrinsically difficult nature of the advection promoted by the geometry of the jet, coupled with prompt diffusion from the adjacent wall. Previous experimental investigations have sought to characterize the hydraulic and thermal behavior of such flows, however the physics promoted by parallel coplanar round jets has received inadequate experimental attention. The current effort is comprised of three parallel, coplanar, equidistant round jets issuing vertically downward into a pseudo-unconfined test section. The outer diameters of the jets are placed tangentially along a smooth flat plate. Non-intrusive optical techniques are incorporated for both hydraulic and thermal observations. Preliminary tests provide accurate inlet boundary conditions for each case. Reference metrics are captured during testing to account for ambient effects and readings inside of the test section. By varying the velocity and temperature inlet parameters, insights are drawn regarding the effects on the merging point (MP) and combined point (CP) of both the flow and thermal fields. Velocity fields in the plane normal to the wall yield additional insight into the deceleration caused by dissipation from both the plate and surrounding stagnant fluid.

Tensile behaviors of three-dimensionally free-formable titanium mesh plates for bone graft applications

NASA Astrophysics Data System (ADS)

He, Jianmei

2017-11-01

Present metal artificial bones for bone grafts have the problems like too heavy and excessive elastic modulus compared with natural bones. In this study, three-dimensionally (3D) free-formable titanium mesh plates for bone graft applications was introduced to improve these problems. Fundamental mesh shapes and patterns were designed under different base shapes and design parameters through three dimensional CAD tools from higher flexibility and strength points of view. Based on the designed mesh shape and patterns, sample specimens of titanium mesh plates with different base shapes and design variables were manufactured through laser processing. Tensile properties of the sample titanium mesh plates like volume density, tensile elastic modulus were experimentally and analytically evaluated. Experimental results showed that such titanium mesh plates had much higher flexibility and their mechanical properties could be controlled to close to the natural bones. More details on the mechanical properties of titanium mesh plates including compression, bending, torsion and durability will be carried out in future study.

INJECTION TO RAPID DIFFUSIVE SHOCK ACCELERATION AT PERPENDICULAR SHOCKS IN PARTIALLY IONIZED PLASMAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ohira, Yutaka, E-mail: ohira@phys.aoyama.ac.jp

2016-08-10

We present a three-dimensional hybrid simulation of a collisionless perpendicular shock in a partially ionized plasma for the first time. In this simulation, the shock velocity and upstream ionization fraction are v {sub sh} ≈ 1333 km s{sup −1} and f {sub i} ∼ 0.5, which are typical values for isolated young supernova remnants (SNRs) in the interstellar medium. We confirm previous two-dimensional simulation results showing that downstream hydrogen atoms leak into the upstream region and are accelerated by the pickup process in the upstream region, and large magnetic field fluctuations are generated both in the upstream and downstream regions.more » In addition, we find that the magnetic field fluctuations have three-dimensional structures and the leaking hydrogen atoms are injected into the diffusive shock acceleration (DSA) at the perpendicular shock after the pickup process. The observed DSA can be interpreted as shock drift acceleration with scattering. In this simulation, particles are accelerated to v ∼ 100 v {sub sh} ∼ 0.3 c within ∼100 gyroperiods. The acceleration timescale is faster than that of DSA in parallel shocks. Our simulation results suggest that SNRs can accelerate cosmic rays to 10{sup 15.5} eV (the knee) during the Sedov phase.« less

Evaluation of molecular dynamics simulation methods for ionic liquid electric double layers.

PubMed

Haskins, Justin B; Lawson, John W

2016-05-14

We investigate how systematically increasing the accuracy of various molecular dynamics modeling techniques influences the structure and capacitance of ionic liquid electric double layers (EDLs). The techniques probed concern long-range electrostatic interactions, electrode charging (constant charge versus constant potential conditions), and electrolyte polarizability. Our simulations are performed on a quasi-two-dimensional, or slab-like, model capacitor, which is composed of a polarizable ionic liquid electrolyte, [EMIM][BF4], interfaced between two graphite electrodes. To ensure an accurate representation of EDL differential capacitance, we derive new fluctuation formulas that resolve the differential capacitance as a function of electrode charge or electrode potential. The magnitude of differential capacitance shows sensitivity to different long-range electrostatic summation techniques, while the shape of differential capacitance is affected by charging technique and the polarizability of the electrolyte. For long-range summation techniques, errors in magnitude can be mitigated by employing two-dimensional or corrected three dimensional electrostatic summations, which led to electric fields that conform to those of a classical electrostatic parallel plate capacitor. With respect to charging, the changes in shape are a result of ions in the Stern layer (i.e., ions at the electrode surface) having a higher electrostatic affinity to constant potential electrodes than to constant charge electrodes. For electrolyte polarizability, shape changes originate from induced dipoles that soften the interaction of Stern layer ions with the electrode. The softening is traced to ion correlations vertical to the electrode surface that induce dipoles that oppose double layer formation. In general, our analysis indicates an accuracy dependent differential capacitance profile that transitions from the characteristic camel shape with coarser representations to a more diffuse profile with finer representations.

A Green's function method for two-dimensional reactive solute transport in a parallel fracture-matrix system

NASA Astrophysics Data System (ADS)

Chen, Kewei; Zhan, Hongbin

2018-06-01

The reactive solute transport in a single fracture bounded by upper and lower matrixes is a classical problem that captures the dominant factors affecting transport behavior beyond pore scale. A parallel fracture-matrix system which considers the interaction among multiple paralleled fractures is an extension to a single fracture-matrix system. The existing analytical or semi-analytical solution for solute transport in a parallel fracture-matrix simplifies the problem to various degrees, such as neglecting the transverse dispersion in the fracture and/or the longitudinal diffusion in the matrix. The difficulty of solving the full two-dimensional (2-D) problem lies in the calculation of the mass exchange between the fracture and matrix. In this study, we propose an innovative Green's function approach to address the 2-D reactive solute transport in a parallel fracture-matrix system. The flux at the interface is calculated numerically. It is found that the transverse dispersion in the fracture can be safely neglected due to the small scale of fracture aperture. However, neglecting the longitudinal matrix diffusion would overestimate the concentration profile near the solute entrance face and underestimate the concentration profile at the far side. The error caused by neglecting the longitudinal matrix diffusion decreases with increasing Peclet number. The longitudinal matrix diffusion does not have obvious influence on the concentration profile in long-term. The developed model is applied to a non-aqueous-phase-liquid (DNAPL) contamination field case in New Haven Arkose of Connecticut in USA to estimate the Trichloroethylene (TCE) behavior over 40 years. The ratio of TCE mass stored in the matrix and the injected TCE mass increases above 90% in less than 10 years.

A cellular automaton method to simulate the microstructure and evolution of low-enriched uranium (LEU) U–Mo/Al dispersion type fuel plates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drera, Saleem S.; Hofman, Gerard L.; Kee, Robert J.

Low-enriched uranium (LEU) fuel plates for high power materials test reactors (MTR) are composed of nominally spherical uranium-molybdenum (U-Mo) particles within an aluminum matrix. Fresh U-Mo particles typically range between 10 and 100 mu m in diameter, with particle volume fractions up to 50%. As the fuel ages, reaction-diffusion processes cause the formation and growth of interaction layers that surround the fuel particles. The growth rate depends upon the temperature and radiation environment. The cellular automaton algorithm described in this paper can synthesize realistic random fuel-particle structures and simulate the growth of the intermetallic interaction layers. Examples in the presentmore » paper pack approximately 1000 particles into three-dimensional rectangular fuel structures that are approximately 1 mm on each side. The computational approach is designed to yield synthetic microstructures consistent with images from actual fuel plates and is validated by comparison with empirical data on actual fuel plates. (C) 2014 Elsevier B.V. All rights reserved.« less

Implementation of one and three dimensional models for heat transfer coeffcient identification over the plate cooled by the circular water jets

NASA Astrophysics Data System (ADS)

Malinowski, Zbigniew; Cebo-Rudnicka, Agnieszka; Hadała, Beata; Szajding, Artur; Telejko, Tadeusz

2017-10-01

A cooling rate affects the mechanical properties of steel which strongly depend on microstructure evolution processes. The heat transfer boundary condition for the numerical simulation of steel cooling by water jets can be determined from the local one dimensional or from the three dimensional inverse solutions in space and time. In the present study the inconel plate has been heated to about 900 °C and then cooled by six circular water jets. The plate temperature has been measured by 30 thermocouples. The heat transfer coefficient and the heat flux distributions at the plate surface have been determined in time and space. The one dimensional solutions have given a local error to the heat transfer coefficient of about 35%. The three dimensional inverse solution has allowed reducing the local error to about 20%. The uncertainty test has confirmed that a better approximation of the heat transfer coefficient distribution over the cooled surface can be obtained even for limited number of thermocouples. In such a case it was necessary to constrain the inverse solution with the interpolated temperature sensors.

X-ray-diffraction study of in-plane and interlayer correlations in layered compounds AgxTiS2

NASA Astrophysics Data System (ADS)

Kuroiwa, Yoshihiro; Ohshima, Ken-Ichi; Watanabe, Yousuke

1990-12-01

X-ray measurements have been performed on the development of in-plane and interplanar correlations of intercalated Ag atoms in stage-2 and -1 AgxTiS2 single crystals. The abrupt change of the c-axis parameter for stage-2 Ag0.15TiS2 at around 250 K, due to the structural transformation of the stacking sequence, was observed, although the a-axis parameter changes continuously. Rodlike diffuse scattering parallel to c* at 1/31/3.0, 2/32/3.0, and their equivalent positions is observed for stage-2 Ag0.15TiS2 above 250 K and shows the two-dimensional (2D) feature of the disordered state. Such a diffuse rod is modulated below 250 K, with maxima appearing at every half-integer. This reveals an enhancement of the three-dimensional nature and a stacking sequence αβαβ... . By analyzing rodlike diffuse scattering at 350, 300, 280, and 250 K for stage-2 Ag0.15TiS2, the 2D short-range-order parameters were determined. By comparing the 2D short-range-order parameters with the 2D Ornstein-Zernike correlation function, it was obtained that the correlation length varies from 4.1+/-0.6 Å at 350 K to 37.1+/-1.6 Å at 250 K. These results can be interpreted with the use of the Daumas-Hérold island model. On the other hand, for stage-1 AgxTiS2, the modulation of the diffuse rod parallel to the c* axis at 1/31/3.0, 2/32/3.0, and their equivalent positions was observed at room temperature, which shows the 3D nature.

Kubo conductivity of a strongly magnetized two-dimensional plasma.

NASA Technical Reports Server (NTRS)

Montgomery, D.; Tappert, F.

1971-01-01

The Kubo formula is used to evaluate the bulk electrical conductivity of a two-dimensional guiding-center plasma in a strong dc magnetic field. The particles interact only electrostatically. An ?anomalous' electrical conductivity is derived for this system, which parallels a recent result of Taylor and McNamara for the coefficient of spatial diffusion.

DSMC Studies of the Richtmyer-Meshkov Instability

NASA Astrophysics Data System (ADS)

Gallis, M. A.; Koehler, T. P.; Torczynski, J. R.

2014-11-01

A new exascale-capable Direct Simulation Monte Carlo (DSMC) code, SPARTA, developed to be highly efficient on massively parallel computers, has extended the applicability of DSMC to challenging, transient three-dimensional problems in the continuum regime. Because DSMC inherently accounts for compressibility, viscosity, and diffusivity, it has the potential to improve the understanding of the mechanisms responsible for hydrodynamic instabilities. Here, the Richtmyer-Meshkov instability at the interface between two gases was studied parametrically using SPARTA. Simulations performed on Sequoia, an IBM Blue Gene/Q supercomputer at Lawrence Livermore National Laboratory, are used to investigate various Atwood numbers (0.33-0.94) and Mach numbers (1.2-12.0) for two-dimensional and three-dimensional perturbations. Comparisons with theoretical predictions demonstrate that DSMC accurately predicts the early-time growth of the instability. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Large-scale three-dimensional phase-field simulations for phase coarsening at ultrahigh volume fraction on high-performance architectures

NASA Astrophysics Data System (ADS)

Yan, Hui; Wang, K. G.; Jones, Jim E.

2016-06-01

A parallel algorithm for large-scale three-dimensional phase-field simulations of phase coarsening is developed and implemented on high-performance architectures. From the large-scale simulations, a new kinetics in phase coarsening in the region of ultrahigh volume fraction is found. The parallel implementation is capable of harnessing the greater computer power available from high-performance architectures. The parallelized code enables increase in three-dimensional simulation system size up to a 5123 grid cube. Through the parallelized code, practical runtime can be achieved for three-dimensional large-scale simulations, and the statistical significance of the results from these high resolution parallel simulations are greatly improved over those obtainable from serial simulations. A detailed performance analysis on speed-up and scalability is presented, showing good scalability which improves with increasing problem size. In addition, a model for prediction of runtime is developed, which shows a good agreement with actual run time from numerical tests.

Influence of the three-dimensional heterogeneous roughness on electrokinetic transport in microchannels.

PubMed

Hu, Yandong; Werner, Carsten; Li, Dongqing

2004-12-15

Surface roughness has been considered as a passive means of enhancing species mixing in electroosmotic flow through microfluidic systems. It is highly desirable to understand the synergetic effect of three-dimensional (3D) roughness and surface heterogeneity on the electrokinetic flow through microchannels. In this study, we developed a three-dimensional finite-volume-based numerical model to simulate electroosmotic transport in a slit microchannel (formed between two parallel plates) with numerous heterogeneous prismatic roughness elements arranged symmetrically and asymmetrically on the microchannel walls. We consider that all 3D prismatic rough elements have the same surface charge or zeta potential, the substrate (the microchannel wall) surface has a different zeta potential. The results showed that the rough channel's geometry and the electroosmotic mobility ratio of the roughness elements' surface to that of the substrate, epsilon(mu), have a dramatic influence on the induced-pressure field, the electroosmotic flow patterns, and the electroosmotic flow rate in the heterogeneous rough microchannels. The associated sample-species transport presents a tidal-wave-like concentration field at the intersection between four neighboring rough elements under low epsilon(mu) values and has a concentration field similar to that of the smooth channels under high epsilon(mu) values.

Vectorization of a particle simulation method for hypersonic rarefied flow

NASA Technical Reports Server (NTRS)

Mcdonald, Jeffrey D.; Baganoff, Donald

1988-01-01

An efficient particle simulation technique for hypersonic rarefied flows is presented at an algorithmic and implementation level. The implementation is for a vector computer architecture, specifically the Cray-2. The method models an ideal diatomic Maxwell molecule with three translational and two rotational degrees of freedom. Algorithms are designed specifically for compatibility with fine grain parallelism by reducing the number of data dependencies in the computation. By insisting on this compatibility, the method is capable of performing simulation on a much larger scale than previously possible. A two-dimensional simulation of supersonic flow over a wedge is carried out for the near-continuum limit where the gas is in equilibrium and the ideal solution can be used as a check on the accuracy of the gas model employed in the method. Also, a three-dimensional, Mach 8, rarefied flow about a finite-span flat plate at a 45 degree angle of attack was simulated. It utilized over 10 to the 7th particles carried through 400 discrete time steps in less than one hour of Cray-2 CPU time. This problem was chosen to exhibit the capability of the method in handling a large number of particles and a true three-dimensional geometry.

Evaluation of a two-dimensional numerical model for air quality simulation in a street canyon

NASA Astrophysics Data System (ADS)

Okamoto, Shin `Ichi; Lin, Fu Chi; Yamada, Hiroaki; Shiozawa, Kiyoshige

For many urban areas, the most severe air pollution caused by automobile emissions appears along a road surrounded by tall buildings: the so=called street canyon. A practical two-dimensional numerical model has been developed to be applied to this kind of road structure. This model contains two submodels: a wind-field model and a diffusion model based on a Monte Carlo particle scheme. In order to evaluate the predictive performance of this model, an air quality simulation was carried out at three trunk roads in the Tokyo metropolitan area: Nishi-Shimbashi, Aoyama and Kanda-Nishikicho (using SF 6 as a tracer and NO x measurement). Since this model has two-dimensional properties and cannot be used for the parallel wind condition, the perpendicular wind condition was selected for the simulation. The correlation coefficients for the SF 6 and NO x data in Aoyama were 0.67 and 0.62, respectively. When predictive performance of this model is compared with other models, this model is comparable to the SRI model, and superior to the APPS three-dimensional numerical model.

Three-Point Gear/Lead Screw Positioning

NASA Technical Reports Server (NTRS)

Calco, Frank S.

1993-01-01

Triple-ganged-lead-screw positioning mechanism drives movable plate toward or away from fixed plate and keeps plates parallel to each other. Designed for use in tuning microwave resonant cavity. Other potential applications include adjustable bed plates and cantilever tail stocks in machine tools, adjustable platforms for optical equipment, and lifting platforms.

Casimir force in O(n) systems with a diffuse interface.

PubMed

Dantchev, Daniel; Grüneberg, Daniel

2009-04-01

We study the behavior of the Casimir force in O(n) systems with a diffuse interface and slab geometry infinity;{d-1}xL , where 2infinity limit of O(n) models with antiperiodic boundary conditions applied along the finite dimension L of the film. We observe that the Casimir amplitude Delta_{Casimir}(dmid R:J_{ perpendicular},J_{ parallel}) of the anisotropic d -dimensional system is related to that of the isotropic system Delta_{Casimir}(d) via Delta_{Casimir}(dmid R:J_{ perpendicular},J_{ parallel})=(J_{ perpendicular}J_{ parallel});{(d-1)2}Delta_{Casimir}(d) . For d=3 we derive the exact Casimir amplitude Delta_{Casimir}(3,mid R:J_{ perpendicular},J_{ parallel})=[Cl_{2}(pi3)3-zeta(3)(6pi)](J_{ perpendicular}J_{ parallel}) , as well as the exact scaling functions of the Casimir force and of the helicity modulus Upsilon(T,L) . We obtain that beta_{c}Upsilon(T_{c},L)=(2pi;{2})[Cl_{2}(pi3)3+7zeta(3)(30pi)](J_{ perpendicular}J_{ parallel})L;{-1} , where T_{c} is the critical temperature of the bulk system. We find that the contributions in the excess free energy due to the existence of a diffuse interface result in a repulsive Casimir force in the whole temperature region.

Three-dimensional displacement measurement of image point by point-diffraction interferometry

NASA Astrophysics Data System (ADS)

He, Xiao; Chen, Lingfeng; Meng, Xiaojie; Yu, Lei

2018-01-01

This paper presents a method for measuring the three-dimensional (3-D) displacement of an image point based on point-diffraction interferometry. An object Point-light-source (PLS) interferes with a fixed PLS and its interferograms are captured by an exit pupil. When the image point of the object PLS is slightly shifted to a new position, the wavefront of the image PLS changes. And its interferograms also change. Processing these figures (captured before and after the movement), the wavefront difference of the image PLS can be obtained and it contains the information of three-dimensional (3-D) displacement of the image PLS. However, the information of its three-dimensional (3-D) displacement cannot be calculated until the distance between the image PLS and the exit pupil is calibrated. Therefore, we use a plane-parallel-plate with a known refractive index and thickness to determine this distance, which is based on the Snell's law for small angle of incidence. Thus, since the distance between the exit pupil and the image PLS is a known quantity, the 3-D displacement of the image PLS can be simultaneously calculated through two interference measurements. Preliminary experimental results indicate that its relative error is below 0.3%. With the ability to accurately locate an image point (whatever it is real or virtual), a fiber point-light-source can act as the reticle by itself in optical measurement.

Contribution of human skin topography to the characterization of dynamic skin tension during senescence: morpho-mechanical approach

NASA Astrophysics Data System (ADS)

Zahouani, H.; Djaghloul, M.; Vargiolu, R.; Mezghani, S.; Mansori, M. E. L.

2014-03-01

The structuring of the dermis with a network of collagen and elastic fibres gives a three-dimensional structure to the skin network with directions perpendicular and parallel to the skin surface. This three-dimensional morphology prints on the surface of the stratum corneum a three dimensional network of lines which express the mechanical tension of the skin at rest. To evaluate the changes of skin morphology, we used a three-dimensional confocal microscopy and characterization of skin imaging of volar forearm microrelief. We have accurately characterize the role of skin line network during chronological aging with the identification of depth scales on the network of lines (z <= 60μm) and the network of lines covering Langer's lines (z > 60 microns). During aging has been highlighted lower rows for elastic fibres, the decrease weakened the tension and results in enlargement of the plates of the microrelief, which gives us a geometric pertinent indicator to quantify the loss of skin tension and assess the stage of aging. The study of 120 Caucasian women shows that ageing in the volar forearm zone results in changes in the morphology of the line network organisation. The decrease in secondary lines (z <= 60 μm) is counterbalanced by an increase in the depth of the primary lines (z > 60 μm) and an accentuation of the anisotropy index.

Deformational History and Rotation of the Leeward Antilles Island Arc: Results of the BOLIVAR Project

NASA Astrophysics Data System (ADS)

Beardsley, A. G.; Avé Lallemant, H. G.

2005-12-01

The Leeward Antilles island arc is located offshore northern Venezuela and includes Aruba, Curaçao, and Bonaire (ABCs). The ABCs trend WNW-ESE parallel to the obliquely convergent Caribbean-South American plate boundary zone. Field work on the ABCs has provided new structural data supporting a minimum of 90° clockwise rotation of the islands within the diffuse plate boundary zone. Analysis of faulting, bedding, and cleavages suggest three phases of deformation (D1-D3). The oldest phase of deformation, D1, is characterized by northeast trending normal faults, northwest trending fold axes and cleavages, and northeast striking dextral strike-slip faults. East striking sinstral strike-slip faults are rare. The second phase of deformation, D2, is represented by west-northwest trending thrust faults, north-northeast striking normal faults, northwest trending dextral strike-slip faults, and northeast striking sinstral strike-slip faults. Finally, the youngest phase of deformation, D3, is characterized by northeast striking thrust faults, northwest striking normal faults, east-west dextral strike-slip faults, and north-northwest sinstral strike-slip faults. Quartz and calcite veins were also studied on the ABCs. Cross-cutting relationships in outcrop suggest three phases of veining (V1-V3). The oldest veins, V1, trend northeastward; V2 veins trend northward; and the youngest veins, V3, trend northwestward. Additionally, joints were measured on the ABCs. On Bonaire and Curaçao, joints trend approximately northeast while joints on Aruba are almost random with a slight preference for west-northwest. Fluid inclusion analysis of quartz and calcite veins provides additional information about the pressure and temperature conditions of the deformation phases. Preliminary results from the earliest veins (V1) show a single deformational event on Aruba and Bonaire. On Bonaire, they exhibit both hydrostatic and lithostatic pressure conditions. This new data supports three stages of deformation accompanied by rotation of the ABCs. The structures identified suggest a clockwise rotation of the principal stress orientation since the Late Cretaceous. D1 deformation and rotation occurred at the southeastern Caribbean plate margin beginning approximately 73 Ma on Aruba. Arc-parallel strike-slip motion rotated the islands clockwise 90° Internal deformation features of the island blocks are consistent with an obliquely convergent plate boundary. D2 deformation is characterized by clockwise block rotation facilitated by dextral strike-slip faults defining the northern and southern boundaries of the diffuse plate boundary zone. Most likely, D2 correlates to the Eocene change in plate motions due to convergence between North and South America, approximately 55 Ma. The youngest phase of deformation and rotation, D3, happens along the arcuate South Caribbean Deformed Belt. Since approximately 25 Ma, rotation and development of northwest trending pull-apart basins between the ABCs progressed. Northeastward motion of the Maracaibo block may also contribute to recent rotation of the island arc.

A unified theory for laminated plates

NASA Astrophysics Data System (ADS)

Guiamatsia Tafeuvoukeng, Irene

A literature survey on plate and beam theories show how the advent of the finite element method and the variational method circa 1940 have been a great stimulant for the research in this field. The initial thin plate formulation has been incrementally expanded to treat the isotropic thick plate, the anisotropic single layer, and then laminated plates. It appears however that current formulations still fall into one of two categories: (1) The formulation is tailored for a specific laminate and/or loading case; (2) or the formulation is too complicated to be of practical relevance. In this work a new unifying approach to laminated plate formulation is presented. All laminated plates, including sandwich panels, subjected to any surface load and with any boundary conditions are treated within a single model. In addition, the fundamental behavior of the plate as a two-dimensional structural element is explained. The novel idea is the introduction of fundamental state solutions, which are analytical far field stress and strain solutions of the laminated plate subjected to a set of hierarchical primary loads, the fundamental loads. These loads are carefully selected to form a basis of the load space, and corresponding solutions are superposed to obtain extremely accurate predictions of the three dimensional solution. six,y,z =aklx,y sikl z where i = 1,..., 6; 1=1,...,l max is a substate of the kth fundamental state k=1,2,3,... Typically, a fundamental state solution is expressed as a through-thickness function (z), while the amplitudes of each fundamental load are found from two dimensional finite element solution as a function of in-plane coordinates (x,y). Three major contributions are produced in this work: (1) A complete calibration of the plate as a two-dimensional structure is performed with pure bending and constant shear fundamental states. (2) There are four independent ways to apply a constant shear resultant on a plate, as opposed to one for a beam. This makes it impossible to define a unique 2 x 2 transverse shear stiffness matrix. Therefore the traditional problem of the shear correction factor loses all relevance. It is however shown that an explicit transverse constitutive relation can be obtained for isotropic-layered laminates or single-layers. (3) Higher accuracy, three-dimensional solutions are obtained using a two-dimensional finite element model with a complexity level (degrees of freedom) similar to the Reissner-Mindlin plate. The proof of concept is realized using Pagano solution for rectangular plates under sinusoidal load, for a sandwich panel. Additional comparisons are also performed for four and six-layer symmetric and antisymmetric laminates, between the new plate theory results and full three-dimensional finite element solutions.

Three-Dimensional Transport Modeling for Proton Exchange Membrane(PEM) Fuel Cell with Micro Parallel Flow Field

PubMed Central

Lee, Pil Hyong; Han, Sang Seok; Hwang, Sang Soon

2008-01-01

Modeling and simulation for heat and mass transport in micro channel are being used extensively in researches and industrial applications to gain better understanding of the fundamental processes and to optimize fuel cell designs before building a prototype for engineering application. In this study, we used a single-phase, fully three dimensional simulation model for PEMFC that can deal with both anode and cathode flow field for examining the micro flow channel with electrochemical reaction. The results show that hydrogen and oxygen were solely supplied to the membrane by diffusion mechanism rather than convection transport, and the higher pressure drop at cathode side is thought to be caused by higher flow rate of oxygen at cathode. And it is found that the amount of water in cathode channel was determined by water formation due to electrochemical reaction plus electro-osmotic mass flux directing toward the cathode side. And it is very important to model the back diffusion and electro-osmotic mass flux accurately since the two flux was closely correlated each other and greatly influenced for determination of ionic conductivity of the membrane which directly affects the performance of fuel cell. PMID:27879774

Artifact correction in diffusion MRI of non-human primate brains on a clinical 3T scanner.

PubMed

Zhang, Xiaodong; Kirsch, John E; Zhong, Xiaodong

2016-02-01

Smearing artifacts were observed and investigated in diffusion tensor imaging (DTI) studies of macaque monkeys on a clinical whole-body 3T scanner. Four adult macaques were utilized to evaluate DTI artifacts. DTI images were acquired with a single-shot echo-planar imaging (EPI) sequence using a parallel imaging technique. The smearing artifacts observed on the diffusion-weighted images and fractional anisotropy maps were caused by the incomplete fat suppression due to the irregular macaque frontal skull geometry and anatomy. The artifact can be reduced substantially using a novel three-dimensional (3D) shimming procedure. The smearing artifacts observed on diffusion weighted images and fractional anisotropy (FA) maps of macaque brains can be reduced substantially using a robust 3D shimming approach. The DTI protocol combined with the shimming procedure could be a robust approach to examine brain connectivity and white matter integrity of non-human primates using a conventional clinical setting. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Relativistic analysis of stochastic kinematics

NASA Astrophysics Data System (ADS)

Giona, Massimiliano

2017-10-01

The relativistic analysis of stochastic kinematics is developed in order to determine the transformation of the effective diffusivity tensor in inertial frames. Poisson-Kac stochastic processes are initially considered. For one-dimensional spatial models, the effective diffusion coefficient measured in a frame Σ moving with velocity w with respect to the rest frame of the stochastic process is inversely proportional to the third power of the Lorentz factor γ (w ) =(1-w2/c2) -1 /2 . Subsequently, higher-dimensional processes are analyzed and it is shown that the diffusivity tensor in a moving frame becomes nonisotropic: The diffusivities parallel and orthogonal to the velocity of the moving frame scale differently with respect to γ (w ) . The analysis of discrete space-time diffusion processes permits one to obtain a general transformation theory of the tensor diffusivity, confirmed by several different simulation experiments. Several implications of the theory are also addressed and discussed.

Failure modes for compression loaded angle-ply plates with holes

NASA Technical Reports Server (NTRS)

Burns, S. W.; Herakovich, C. T.; Williams, J. G.

1987-01-01

A combined theoretical-experimental investigation of failure in notched, graphite-epoxy, angle-ply laminates subjected to far-field compression loading indicates that failure generally initiates on the hole boundary and propagates along a line parallel to the fiber orientation of the laminate. The strength of notched laminates with specimen width-to-hole diameter ratios of 5 and 10 are compared to the strength of unnotched laminates. The experimental results are complemented by a three-dimensional finite element stress analysis that includes interlaminar stresses around holes in (+/- theta)s laminates. The finite element predictions indicate that failure is initiated by shear stresses at the hole boundary.

Polymer diffusion in the interphase between surface and solution.

PubMed

Weger, Lukas; Weidmann, Monika; Ali, Wael; Hildebrandt, Marcus; Gutmann, Jochen Stefan; Hoffmann-Jacobsen, Kerstin

2018-05-22

Total internal reflection fluorescence correlation spectroscopy (TIR-FCS) is applied to study the self-diffusion of polyethylene glycol solutions in the presence of weakly attractive interfaces. Glass coverslips modified with aminopropyl- and propyl-terminated silanes are used to study the influence of solid surfaces on polymer diffusion. A model of three phases of polymer diffusion allows to describe the experimental fluorescence autocorrelation functions. Besides the two-dimensional diffusion of adsorbed polymer on the substrate and three-dimensional free diffusion in bulk solution, a third diffusion time scale is observed with intermediate diffusion times. This retarded three-dimensional diffusion in solution is assigned to long range effects of solid surfaces on diffusional dynamics of polymers. The respective diffusion constants show Rouse scaling (D~N -1 ) indicating a screening of hydrodynamic interactions by the presence of the surface. Hence, the presented TIR-FCS method proves to be a valuable tool to investigate the effect of surfaces on polymer diffusion beyond the first adsorbed polymer layer on the 100 nm length scale.

The 2.5-dimensional equivalent sources method for directly exposed and shielded urban canyons.

PubMed

Hornikx, Maarten; Forssén, Jens

2007-11-01

When a domain in outdoor acoustics is invariant in one direction, an inverse Fourier transform can be used to transform solutions of the two-dimensional Helmholtz equation to a solution of the three-dimensional Helmholtz equation for arbitrary source and observer positions, thereby reducing the computational costs. This previously published approach [D. Duhamel, J. Sound Vib. 197, 547-571 (1996)] is called a 2.5-dimensional method and has here been extended to the urban geometry of parallel canyons, thereby using the equivalent sources method to generate the two-dimensional solutions. No atmospheric effects are considered. To keep the error arising from the transform small, two-dimensional solutions with a very fine frequency resolution are necessary due to the multiple reflections in the canyons. Using the transform, the solution for an incoherent line source can be obtained much more efficiently than by using the three-dimensional solution. It is shown that the use of a coherent line source for shielded urban canyon observer positions leads mostly to an overprediction of levels and can yield erroneous results for noise abatement schemes. Moreover, the importance of multiple facade reflections in shielded urban areas is emphasized by vehicle pass-by calculations, where cases with absorptive and diffusive surfaces have been modeled.

Accurate reaction-diffusion operator splitting on tetrahedral meshes for parallel stochastic molecular simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hepburn, I.; De Schutter, E., E-mail: erik@oist.jp; Theoretical Neurobiology & Neuroengineering, University of Antwerp, Antwerp 2610

Spatial stochastic molecular simulations in biology are limited by the intense computation required to track molecules in space either in a discrete time or discrete space framework, which has led to the development of parallel methods that can take advantage of the power of modern supercomputers in recent years. We systematically test suggested components of stochastic reaction-diffusion operator splitting in the literature and discuss their effects on accuracy. We introduce an operator splitting implementation for irregular meshes that enhances accuracy with minimal performance cost. We test a range of models in small-scale MPI simulations from simple diffusion models to realisticmore » biological models and find that multi-dimensional geometry partitioning is an important consideration for optimum performance. We demonstrate performance gains of 1-3 orders of magnitude in the parallel implementation, with peak performance strongly dependent on model specification.« less

Controlled Self-Assembly of Low-Dimensional Alq3 Nanostructures from 1D Nanowires to 2D Plates via Intermolecular Interactions

NASA Astrophysics Data System (ADS)

Gu, Jianmin; Yin, Baipeng; Fu, Shaoyan; Jin, Cuihong; Liu, Xin; Bian, Zhenpan; Li, Jianjun; Wang, Lu; Li, Xiaoyu

2018-03-01

Due to the intense influence of the shape and size of the photon building blocks on the limitation and guidance of optical waves, an important strategy is the fabrication of different structures. Herein, organic semiconductor tris-(8-hydroxyquinoline)aluminium (Alq3) nanostructures with controllable morphology, ranging from one-dimensional nanowires to two-dimensional plates, have been prepared through altering intermolecular interactions with employing the anti-solvent diffusion cooperate with solvent-volatilization induced self-assembly method. The morphologies of the formed nanostructures, which are closely related to the stacking modes of the molecules, can be exactly controlled by altering the polarity of anti-solvents that can influence various intermolecular interactions. The synthesis strategy reported here can potentially be extended to other functional organic nanomaterials.

Static Internal Performance of a Two-Dimensional Convergent-Divergent Nozzle with External Shelf

NASA Technical Reports Server (NTRS)

Lamb, Milton; Taylor, John G.; Frassinelli, Mark C.

1996-01-01

An investigation was conducted in the static test facility of the Langley 16-Foot Transonic Tunnel to determine the internal performance of a two-dimensional convergent-divergent nozzle. The nozzle design was tested with dry and afterburning throat areas, which represent different power settings and three expansion ratios. For each of these configurations, three trailing-edge geometries were tested. The baseline geometry had a straight trailing edge. Two different shaping techniques were applied to the baseline nozzle design to reduce radar observables: the scarfed design and the sawtooth design. A flat plate extended downstream of the lower divergent flap trailing edge parallel to the model centerline to form a shelf-like expansion surface. This shelf was designed to shield the plume from ground observation (infrared radiation (IR) signature suppression). The shelf represents the part of the aircraft structure that might be present in an installed configuration. These configurations were tested at nozzle pressure ratios from 2.0 to 12.0.

Tectonic and Magmatic Controls on Extension and Crustalaccretion in Backarc Basins, Insights from the Lau Basin and Southern Mariana Trough

NASA Astrophysics Data System (ADS)

Sleeper, Jonathan D.

This dissertation examines magmatic and tectonic processes in backarc basins, and how they are modulated by plate- and mantle-driven mechanisms. Backarc basins initiate by tectonic rifting near the arc volcanic front and transition to magmatic seafloor spreading. As at mid-ocean ridges (MORs), spreading can be focused in narrow plate boundary zones, but we also describe a diffuse spreading mode particular to backarc basins. At typical MORs away from hot spots and other melting anomalies, spreading rate is the primary control on the rate of mantle upwelling and decompression melting. At backarc spreading centers, water derived from the subducting slab creates an additional mantle-driven source of melt and buoyant upwelling. Furthermore, because basins open primarily in response to trench rollback, which is inherently a non-rigid process, backarc extensional systems often have to respond to a constantly evolving stress regime, generating complex tectonics and unusual plate boundaries not typically found at MORs. The interplay between these plate- and mantle-driven processes gives rise to the variety of tectonic and volcanic morphologies peculiar to backarc basins. Chapter 2 is focused on the Fonualei Rift and Spreading Center in the Lau Basin. The southern portion of the axis is spreading at ultraslow (<20 mm/yr) opening rates in close proximity to the arc volcanic front and axial morphology abruptly changes from a volcanic ridge to spaced volcanic cones resembling arc volcanoes. Spreading rate and arc proximity appear to control transitions between two-dimensional and three-dimensional mantle upwelling and volcanism. In the second study (Chapter 3), I develop a new model for the rollback-driven kinematic and tectonic evolution of the Lau Basin, where microplate tectonics creates rapidly changing plate boundary configurations. The third study (Chapter 4) focuses on the southern Mariana Trough and the transitions between arc rifting, seafloor spreading, and a new mode of "diffuse spreading," where new crust is accreted in broad zones rather than along a narrow spreading axis, apparently controlled by a balance between slab water addition and its extraction due to melting and crustal accretion.

A novel model of photothermal diffusion (PTD) for polymer nano-composite semiconducting of thin circular plate

NASA Astrophysics Data System (ADS)

Lotfy, Kh.

2018-05-01

In this article, theoretical discussions for a novel mathematical-physical Photothermal diffusion (PTD) model in the generalized thermoelasticity theory with photothermal processes and chemical action are introduced. The mean idea of this model depends on the interaction between quasi-particles (plasma waves) that depends on the kind of the used materials, the mechanical forces acting on the surface, the generalized thermo and mass diffusion (due to coupling of temperature fields with thermal waves and chemical potential) and the elastic waves. The one dimensional Laplace transforms is used to obtain the exact solution for some physical and chemical quantities for a thin circular plate of a semiconducting polymer nanocomposite such as silicon (Si). New variables are deduced and discussed. The obtained results of the physical quantities are presented analytically and illustrated graphically with some important applications.

Comparative Three-Dimensional Morphology of Baleen: Cross-Sectional Profiles and Volume Measurements Using CT Images.

PubMed

Jensen, Megan M; Saladrigas, Amalia H; Goldbogen, Jeremy A

2017-11-01

Baleen whales are obligate filter feeders, straining prey-laden seawater through racks of keratinized baleen plates. Despite the importance of baleen to the ecology and natural history of these animals, relatively little work has been done on baleen morphology, particularly with regard to the three-dimensional morphology and structure of baleen. We used computed tomography (CT) scanning to take 3D images of six baleen specimens representing five species, including three complete racks. With these images, we described the three-dimensional shape of the baleen plates using cross-sectional profiles from within the gum tissue to the tip of the plates. We also measured the percentage of each specimen that was composed of either keratinized plate material or was void space between baleen plates, and thus available for seawater flow. Baleen plates have a complex three-dimensional structure with curvature that varies across the anterior-posterior, proximal-distal, and medial-lateral (lingual-labial) axes. These curvatures also vary with location along the baleen rack, and between species. Cross-sectional profiles resemble backwards-facing airfoils, and some specimens display S-shaped, or reflexed, camber. Within a baleen specimen, the intra-baleen void volume correlates with the average bristle diameter for a species, suggesting that essentially, thinner plates (with more space between them for flow) have thinner bristles. Both plate curvature and the relative proportions of plate and void volumes are likely to have implications for the mechanics of mysticete filtration, and future studies are needed to determine the particular functions of these morphological characters. Anat Rec, 300:1942-1952, 2017. © 2017 The Authors The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists. © 2017 The Authors The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.

A GENERALIZED TWO-COMPONENT MODEL OF SOLAR WIND TURBULENCE AND AB INITIO DIFFUSION MEAN-FREE PATHS AND DRIFT LENGTHSCALES OF COSMIC RAYS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiengarten, T.; Fichtner, H.; Kleimann, J.

2016-12-10

We extend a two-component model for the evolution of fluctuations in the solar wind plasma so that it is fully three-dimensional (3D) and also coupled self-consistently to the large-scale magnetohydrodynamic equations describing the background solar wind. The two classes of fluctuations considered are a high-frequency parallel-propagating wave-like piece and a low-frequency quasi-two-dimensional component. For both components, the nonlinear dynamics is dominanted by quasi-perpendicular spectral cascades of energy. Driving of the fluctuations by, for example, velocity shear and pickup ions is included. Numerical solutions to the new model are obtained using the Cronos framework, and validated against previous simpler models. Comparing results frommore » the new model with spacecraft measurements, we find improved agreement relative to earlier models that employ prescribed background solar wind fields. Finally, the new results for the wave-like and quasi-two-dimensional fluctuations are used to calculate ab initio diffusion mean-free paths and drift lengthscales for the transport of cosmic rays in the turbulent solar wind.« less

STAN5: A program for numerical computation of two-dimensional internal and external boundary layer flows

NASA Technical Reports Server (NTRS)

Crawford, M. E.; Kays, W. M.

1976-01-01

A large variety of two dimensional flows can be accommodated by the program, including boundary layers on a flat plate, flow inside nozzles and diffusers (for a prescribed potential flow distribution), flow over axisymmetric bodies, and developing and fully developed flow inside circular pipes and flat ducts. The flows may be laminar or turbulent, and provision is made to handle transition.

A parallel algorithm for the two-dimensional time fractional diffusion equation with implicit difference method.

PubMed

Gong, Chunye; Bao, Weimin; Tang, Guojian; Jiang, Yuewen; Liu, Jie

2014-01-01

It is very time consuming to solve fractional differential equations. The computational complexity of two-dimensional fractional differential equation (2D-TFDE) with iterative implicit finite difference method is O(M(x)M(y)N(2)). In this paper, we present a parallel algorithm for 2D-TFDE and give an in-depth discussion about this algorithm. A task distribution model and data layout with virtual boundary are designed for this parallel algorithm. The experimental results show that the parallel algorithm compares well with the exact solution. The parallel algorithm on single Intel Xeon X5540 CPU runs 3.16-4.17 times faster than the serial algorithm on single CPU core. The parallel efficiency of 81 processes is up to 88.24% compared with 9 processes on a distributed memory cluster system. We do think that the parallel computing technology will become a very basic method for the computational intensive fractional applications in the near future.

Generation of plate tectonics with two-phase grain-damage and pinning: Source-sink model and toroidal flow

NASA Astrophysics Data System (ADS)

Bercovici, David; Ricard, Yanick

2013-03-01

The grain-damage and pinning mechanism of Bercovici and Ricard (2012) for lithospheric shear-localization is employed in two-dimensional flow calculations to test its ability to generate toroidal (strike-slip) motion and influence plate evolution. This mechanism posits that damage to the interface between phases in a polycrystalline material like peridotite (composed primarily of olivine and pyroxene) increases the number of small Zener pinning surfaces, which then constrain mineral grains to ever smaller sizes, regardless of creep mechanism. This effect allows a self-softening feedback in which damage and grain-reduction can co-exist with a grain-size dependent diffusion creep rheology; moreover, grain growth and weak-zone healing are greatly impeded by Zener pinning thereby leading to long-lived relic weak zones. The fluid dynamical calculations employ source-sink driven flow as a proxy for convective poloidal flow (upwelling/downwelling and divergent/convergent motion), and the coupling of this flow with non-linear rheological mechanisms excites toroidal or strike-slip motion. The numerical experiments show that pure dislocation-creep rheology, and grain-damage without Zener pinning (as occurs in a single-phase assemblages) permit only weak localization and toroidal flow; however, the full grain-damage with pinning readily allows focussed localization and intense, plate-like toroidal motion and strike-slip deformation. Rapid plate motion changes are also tested with abrupt rotations of the source-sink field after a plate-like configuration is developed; the post-rotation flow and material property fields retain memory of the original configuration for extensive periods, leading to suboptimally aligned plate boundaries (e.g., strike-slip margins non-parallel to plate motion), oblique subduction, and highly localized, weak and long lived acute plate-boundary junctions such as at what is observed at the Aleutian-Kurile intersection. The grain-damage and pinning theory therefore readily satisfies key plate-tectonic metrics of localized toroidal motion and plate-boundary inheritance, and thus provides a predictive theory for the generation of plate tectonics on Earth and other planets.

Variational asymptotic modeling of composite dimensionally reducible structures

NASA Astrophysics Data System (ADS)

Yu, Wenbin

A general framework to construct accurate reduced models for composite dimensionally reducible structures (beams, plates and shells) was formulated based on two theoretical foundations: decomposition of the rotation tensor and the variational asymptotic method. Two engineering software systems, Variational Asymptotic Beam Sectional Analysis (VABS, new version) and Variational Asymptotic Plate and Shell Analysis (VAPAS), were developed. Several restrictions found in previous work on beam modeling were removed in the present effort. A general formulation of Timoshenko-like cross-sectional analysis was developed, through which the shear center coordinates and a consistent Vlasov model can be obtained. Recovery relations are given to recover the asymptotic approximations for the three-dimensional field variables. A new version of VABS has been developed, which is a much improved program in comparison to the old one. Numerous examples are given for validation. A Reissner-like model being as asymptotically correct as possible was obtained for composite plates and shells. After formulating the three-dimensional elasticity problem in intrinsic form, the variational asymptotic method was used to systematically reduce the dimensionality of the problem by taking advantage of the smallness of the thickness. The through-the-thickness analysis is solved by a one-dimensional finite element method to provide the stiffnesses as input for the two-dimensional nonlinear plate or shell analysis as well as recovery relations to approximately express the three-dimensional results. The known fact that there exists more than one theory that is asymptotically correct to a given order is adopted to cast the refined energy into a Reissner-like form. A two-dimensional nonlinear shell theory consistent with the present modeling process was developed. The engineering computer code VAPAS was developed and inserted into DYMORE to provide an efficient and accurate analysis of composite plates and shells. Numerical results are compared with the exact solutions, and the excellent agreement proves that one can use VAPAS to analyze composite plates and shells efficiently and accurately. In conclusion, rigorous modeling approaches were developed for composite beams, plates and shells within a general framework. No such consistent and general treatment is found in the literature. The associated computer programs VABS and VAPAS are envisioned to have many applications in industry.

Parallelism measurement for base plate of standard artifact with multiple tactile approaches

NASA Astrophysics Data System (ADS)

Ye, Xiuling; Zhao, Yan; Wang, Yiwen; Wang, Zhong; Fu, Luhua; Liu, Changjie

2018-01-01

Nowadays, as workpieces become more precise and more specialized which results in more sophisticated structures and higher accuracy for the artifacts, higher requirements have been put forward for measuring accuracy and measuring methods. As an important method to obtain the size of workpieces, coordinate measuring machine (CMM) has been widely used in many industries. In order to achieve the calibration of a self-developed CMM, it is found that the parallelism of the base plate used for fixing the standard artifact is an important factor which affects the measurement accuracy in the process of studying self-made high-precision standard artifact. And aimed to measure the parallelism of the base plate, by using the existing high-precision CMM, gauge blocks, dial gauge and marble platform with the tactile approach, three methods for parallelism measurement of workpieces are employed, and comparisons are made within the measurement results. The results of experiments show that the final accuracy of all the three methods is able to reach micron level and meets the measurement requirements. Simultaneously, these three approaches are suitable for different measurement conditions which provide a basis for rapid and high-precision measurement under different equipment conditions.

Surface relief model for photopolymers without cover plating.

PubMed

Gallego, S; Márquez, A; Ortuño, M; Francés, J; Marini, S; Beléndez, A; Pascual, I

2011-05-23

Relief surface changes provide interesting possibilities for storing diffractive optical elements on photopolymers and are an important source of information to characterize and understand the material behaviour. In this paper we present a 3-dimensional model based on direct measurements of parameters to predict the relief structures generated on the material. This model is successfully applied to different photopolymers with different values of monomer diffusion. The importance of monomer diffusion in depth is also discussed.

Effect of diffuser vane shape on the performance of a centrifugal compressor stage

NASA Astrophysics Data System (ADS)

Reddy, T. Ch Siva; Ramana Murty, G. V.; Prasad, M. V. S. S. S. M.

2014-04-01

The present paper reports the results of experimental investigations on the effect of diffuser vane shape on the performance of a centrifugal compressor stage. These studies were conducted on the chosen stage having a backward curved impeller of 500 mm tip diameter and 24.5 mm width and its design flow coefficient is ϕd=0.0535. Three different low solidity diffuser vane shapes namely uncambered aerofoil, constant thickness flat plate and circular arc cambered constant thickness plate were chosen as the variants for diffuser vane shape and all the three shapes have the same thickness to chord ratio (t/c=0.1). Flow coefficient, polytropic efficiency, total head coefficient, power coefficient and static pressure recovery coefficient were chosen as the parameters for evaluating the effect of diffuser vane shape on the stage performance. The results show that there is reasonable improvement in stage efficiency and total head coefficient with the use of the chosen diffuser vane shapes as compared to conventional vaneless diffuser. It is also noticed that the aero foil shaped LSD has shown better performance when compared to flat plate and circular arc profiles. The aerofoil vane shape of the diffuser blade is seen to be tolerant over a considerable range of incidence.

Asymptotic derivation of nonlocal plate models from three-dimensional stress gradient elasticity

NASA Astrophysics Data System (ADS)

Hache, F.; Challamel, N.; Elishakoff, I.

2018-01-01

This paper deals with the asymptotic derivation of thin and thick nonlocal plate models at different orders from three-dimensional stress gradient elasticity, through the power series expansions of the displacements in the thickness ratio of the plate. Three nonlocal asymptotic approaches are considered: a partial nonlocality following the thickness of the plate, a partial nonlocality following the two directions of the plates and a full nonlocality (following all the directions). The three asymptotic approaches lead at the zeroth order to a nonlocal Kirchhoff-Love plate model, but differ in the expression of the length scale. The nonlocal asymptotic models coincide at this order with the stress gradient Kirchhoff-Love plate model, only when the nonlocality is following the two directions of the plate and expressed through a nabla operator. This asymptotic model also yields the nonlocal truncated Uflyand-Mindlin plate model at the second order. However, the two other asymptotic models lead to equations that differ from the current existing nonlocal engineering models (stress gradient engineering plate models). The natural frequencies for an all-edges simply supported plate are obtained for each model. It shows that the models provide similar results for low orders of frequencies or small thickness ratio or nonlocal lengths. Moreover, only the asymptotic model with a partial nonlocality following the two directions of the plates is consistent with a stress gradient plate model, whatever the geometry of the plate.

Subcontinental-scale crustal velocity changes along the Pacific-North America plate boundary.

PubMed

Davis, J L; Wernicke, B P; Bisnath, S; Niemi, N A; Elósegui, P

2006-06-29

Transient tectonic deformation has long been noted within approximately 100 km of plate boundary fault zones and within active volcanic regions, but it is unknown whether transient motions also occur at larger scales within plates. Relatively localized transients are known to occur as both seismic and episodic aseismic events, and are generally ascribed to motions of magma bodies, aseismic creep on faults, or elastic or viscoelastic effects associated with earthquakes. However, triggering phenomena and systematic patterns of seismic strain release at subcontinental (approximately 1,000 km) scale along diffuse plate boundaries have long suggested that energy transfer occurs at larger scale. Such transfer appears to occur by the interaction of stresses induced by surface wave propagation and magma or groundwater in the crust, or from large-scale stress diffusion within the oceanic mantle in the decades following clusters of great earthquakes. Here we report geodetic evidence for a coherent, subcontinental-scale change in tectonic velocity along a diffuse approximately 1,000-km-wide deformation zone. Our observations are derived from continuous GPS (Global Positioning System) data collected over the past decade across the Basin and Range province, which absorbs approximately 25 per cent of Pacific-North America relative plate motion. The observed changes in site velocity define a sharp boundary near the centre of the province oriented roughly parallel to the north-northwest relative plate motion vector. We show that sites to the west of this boundary slowed relative to sites east of it by approximately 1 mm yr(-1) starting in late 1999.

Conceptual design of a Bitter-magnet toroidal-field system for the ZEPHYR Ignition Test Reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, J.E.C.; Becker, H.D.; Bobrov, E.S.

1981-05-01

The following problems are described and discussed: (1) parametric studies - these studies examine among other things the interdependence of throat stresses, plasma parameters (margins of ignition) and stored energy. The latter is a measure of cost and is minimized in the present design; (2) magnet configuration - the shape of the plates are considered in detail including standard turns, turns located at beam ports, diagnostic and closure flanges; (3) ripple computation - this section describes the codes by which ripple is computed; (4) field diffusion and nuclear heating - the effect of magnetic field diffusion on heating is consideredmore » along with neutron heating. Current, field and temperature profiles are computed; (5) finite element analysis - the two and three dimensional finite element codes are described and the results discussed in detail; (6) structures engineering - this considers the calculation of critical stresses due to toroidal and overturning forces and discusses the method of constraint of these forces. The Materials Testing Program is also discussed; (7) fabrication - the methods available for the manufacture of the constituent parts of the Bitter plates, the method of assembly and remote maintenance are summarized.« less

A {1,2}-Order Plate Theory Accounting for Three-Dimensional Thermoelastic Deformations in Thick Composite and Sandwich Laminates

NASA Technical Reports Server (NTRS)

Tessler, A.; Annett, M. S.; Gendron, G.

2001-01-01

A {1,2}-order theory for laminated composite and sandwich plates is extended to include thermoelastic effects. The theory incorporates all three-dimensional strains and stresses. Mixed-field assumptions are introduced which include linear in-plane displacements, parabolic transverse displacement and shear strains, and a cubic distribution of the transverse normal stress. Least squares strain compatibility conditions and exact traction boundary conditions are enforced to yield higher polynomial degree distributions for the transverse shear strains and transverse normal stress through the plate thickness. The principle of virtual work is used to derive a 10th-order system of equilibrium equations and associated Poisson boundary conditions. The predictive capability of the theory is demonstrated using a closed-form analytic solution for a simply-supported rectangular plate subjected to a linearly varying temperature field across the thickness. Several thin and moderately thick laminated composite and sandwich plates are analyzed. Numerical comparisons are made with corresponding solutions of the first-order shear deformation theory and three-dimensional elasticity theory. These results, which closely approximate the three-dimensional elasticity solutions, demonstrate that through - the - thickness deformations even in relatively thin and, especially in thick. composite and sandwich laminates can be significant under severe thermal gradients. The {1,2}-order kinematic assumptions insure an overall accurate theory that is in general superior and, in some cases, equivalent to the first-order theory.

Flow of nanofluid past a Riga plate

NASA Astrophysics Data System (ADS)

Ahmad, Adeel; Asghar, Saleem; Afzal, Sumaira

2016-03-01

This paper studies the mixed convection boundary layer flow of a nanofluid past a vertical Riga plate in the presence of strong suction. The mathematical model incorporates the Brownian motion and thermophoresis effects due to nanofluid and the Grinberg-term for the wall parallel Lorentz force due to Riga plate. The analytical solution of the problem is presented using the perturbation method for small Brownian and thermophoresis diffusion parameters. The numerical solution is also presented to ensure the reliability of the asymptotic method. The comparison of the two solutions shows an excellent agreement. The correlation expressions for skin friction, Nusselt number and Sherwood number are developed by performing linear regression on the obtained numerical data. The effects of nanofluid and the Lorentz force due to Riga plate, on the skin friction are discussed.

Stress-intensity factor equations for cracks in three-dimensional finite bodies

NASA Technical Reports Server (NTRS)

Newman, J. C., Jr.; Raju, I. S.

1981-01-01

Empirical stress intensity factor equations are presented for embedded elliptical cracks, semi-elliptical surface cracks, quarter-elliptical corner cracks, semi-elliptical surface cracks at a hole, and quarter-elliptical corner cracks at a hole in finite plates. The plates were subjected to remote tensile loading. Equations give stress intensity factors as a function of parametric angle, crack depth, crack length, plate thickness, and where applicable, hole radius. The stress intensity factors used to develop the equations were obtained from three dimensional finite element analyses of these crack configurations.

SubductionGenerator: A program to build three-dimensional plate configurations

NASA Astrophysics Data System (ADS)

Jadamec, M. A.; Kreylos, O.; Billen, M. I.; Turcotte, D. L.; Knepley, M.

2016-12-01

Geologic, geochemical, and geophysical data from subduction zones indicate that a two-dimensional paradigm for plate tectonic boundaries is no longer adequate to explain the observations. Many open source software packages exist to simulate the viscous flow of the Earth, such as the dynamics of subduction. However, there are few open source programs that generate the three-dimensional model input. We present an open source software program, SubductionGenerator, that constructs the three-dimensional initial thermal structure and plate boundary structure. A 3D model mesh and tectonic configuration are constructed based on a user specified model domain, slab surface, seafloor age grid file, and shear zone surface. The initial 3D thermal structure for the plates and mantle within the model domain is then constructed using a series of libraries within the code that use a half-space cooling model, plate cooling model, and smoothing functions. The code maps the initial 3D thermal structure and the 3D plate interface onto the mesh nodes using a series of libraries including a k-d tree to increase efficiency. In this way, complicated geometries and multiple plates with variable thickness can be built onto a multi-resolution finite element mesh with a 3D thermal structure and 3D isotropic shear zones oriented at any angle with respect to the grid. SubductionGenerator is aimed at model set-ups more representative of the earth, which can be particularly challenging to construct. Examples include subduction zones where the physical attributes vary in space, such as slab dip and temperature, and overriding plate temperature and thickness. Thus, the program can been used to construct initial tectonic configurations for triple junctions and plate boundary corners.

Development and verification of global/local analysis techniques for laminated composites

NASA Technical Reports Server (NTRS)

Thompson, Danniella Muheim; Griffin, O. Hayden, Jr.

1991-01-01

A two-dimensional to three-dimensional global/local finite element approach was developed, verified, and applied to a laminated composite plate of finite width and length containing a central circular hole. The resulting stress fields for axial compression loads were examined for several symmetric stacking sequences and hole sizes. Verification was based on comparison of the displacements and the stress fields with those accepted trends from previous free edge investigations and a complete three-dimensional finite element solution of the plate. The laminates in the compression study included symmetric cross-ply, angle-ply and quasi-isotropic stacking sequences. The entire plate was selected as the global model and analyzed with two-dimensional finite elements. Displacements along a region identified as the global/local interface were applied in a kinematically consistent fashion to independent three-dimensional local models. Local areas of interest in the plate included a portion of the straight free edge near the hole, and the immediate area around the hole. Interlaminar stress results obtained from the global/local analyses compares well with previously reported trends, and some new conclusions about interlaminar stress fields in plates with different laminate orientations and hole sizes are presented for compressive loading. The effectiveness of the global/local procedure in reducing the computational effort required to solve these problems is clearly demonstrated through examination of the computer time required to formulate and solve the linear, static system of equations which result for the global and local analyses to those required for a complete three-dimensional formulation for a cross-ply laminate. Specific processors used during the analyses are described in general terms. The application of this global/local technique is not limited software system, and was developed and described in as general a manner as possible.

3D Modeling of Ultrasonic Wave Interaction with Disbonds and Weak Bonds

NASA Technical Reports Server (NTRS)

Leckey, C.; Hinders, M.

2011-01-01

Ultrasonic techniques, such as the use of guided waves, can be ideal for finding damage in the plate and pipe-like structures used in aerospace applications. However, the interaction of waves with real flaw types and geometries can lead to experimental signals that are difficult to interpret. 3-dimensional (3D) elastic wave simulations can be a powerful tool in understanding the complicated wave scattering involved in flaw detection and for optimizing experimental techniques. We have developed and implemented parallel 3D elastodynamic finite integration technique (3D EFIT) code to investigate Lamb wave scattering from realistic flaws. This paper discusses simulation results for an aluminum-aluminum diffusion disbond and an aluminum-epoxy disbond and compares results from the disbond case to the common artificial flaw type of a flat-bottom hole. The paper also discusses the potential for extending the 3D EFIT equations to incorporate physics-based weak bond models for simulating wave scattering from weak adhesive bonds.

Load Diffusion in Composite and Smart Structures

NASA Technical Reports Server (NTRS)

Horgan, C. O.

2003-01-01

The research carried out here builds on our previous NASA supported research on the general topic of edge effects and load diffusion in composite structures. Further fundamental solid mechanics studies were carried out to provide a basis for assessing the complicated modeling necessary for the multi-functional large scale structures used by NASA. An understanding of the fundamental mechanisms of load diffusion in composite subcomponents is essential in developing primary composite structures. Some specific problems recently considered were those of end effects in smart materials and structures, study of the stress response of pressurized linear piezoelectric cylinders for both static and steady rotating configurations, an analysis of the effect of pre-stressing and pre-polarization on the decay of end effects in piezoelectric solids and investigation of constitutive models for hardening rubber-like materials. Our goal in the study of load diffusion is the development of readily applicable results for the decay lengths in terms of non-dimensional material and geometric parameters. Analytical models of load diffusion behavior are extremely valuable in building an intuitive base for developing refined modeling strategies and assessing results from finite element analyses. The decay behavior of stresses and other field quantities provides a significant aid towards this process. The analysis is also amenable to parameter study with a large parameter space and should be useful in structural tailoring studies. Special purpose analytical models of load diffusion behavior are extremely valuable in building an intuitive base for developing refined modeling strategies and in assessing results from general purpose finite element analyses. For example, a rational basis is needed in choosing where to use three-dimensional to two-dimensional transition finite elements in analyzing stiffened plates and shells. The decay behavior of stresses and other field quantities furnished by this research provides a significant aid towards this element transition issue. A priori knowledge of the extent of boundary-layers induced by edge effects is also useful in determination of the instrumentation location in structural verification tests or in material characterization tests.

Hydroelastic behaviour of a structure exposed to an underwater explosion

PubMed Central

Colicchio, G.; Greco, M.; Brocchini, M.; Faltinsen, O. M.

2015-01-01

The hydroelastic interaction between an underwater explosion and an elastic plate is investigated num- erically through a domain-decomposition strategy. The three-dimensional features of the problem require a large computational effort, which is reduced through a weak coupling between a one-dimensional radial blast solver, which resolves the blast evolution far from the boundaries, and a three-dimensional compressible flow solver used where the interactions between the compression wave and the boundaries take place and the flow becomes three-dimensional. The three-dimensional flow solver at the boundaries is directly coupled with a modal structural solver that models the response of the solid boundaries like elastic plates. This enables one to simulate the fluid–structure interaction as a strong coupling, in order to capture hydroelastic effects. The method has been applied to the experimental case of Hung et al. (2005 Int. J. Impact Eng. 31, 151–168 (doi:10.1016/j.ijimpeng.2003.10.039)) with explosion and structure sufficiently far from other boundaries and successfully validated in terms of the evolution of the acceleration induced on the plate. It was also used to investigate the interaction of an underwater explosion with the bottom of a close-by ship modelled as an orthotropic plate. In the application, the acoustic phase of the fluid–structure interaction is examined, highlighting the need of the fluid–structure coupling to capture correctly the possible inception of cavitation. PMID:25512585

Logarithmic Superdiffusion in Two Dimensional Driven Lattice Gases

NASA Astrophysics Data System (ADS)

Krug, J.; Neiss, R. A.; Schadschneider, A.; Schmidt, J.

2018-03-01

The spreading of density fluctuations in two-dimensional driven diffusive systems is marginally anomalous. Mode coupling theory predicts that the diffusivity in the direction of the drive diverges with time as (ln t)^{2/3} with a prefactor depending on the macroscopic current-density relation and the diffusion tensor of the fluctuating hydrodynamic field equation. Here we present the first numerical verification of this behavior for a particular version of the two-dimensional asymmetric exclusion process. Particles jump strictly asymmetrically along one of the lattice directions and symmetrically along the other, and an anisotropy parameter p governs the ratio between the two rates. Using a novel massively parallel coupling algorithm that strongly reduces the fluctuations in the numerical estimate of the two-point correlation function, we are able to accurately determine the exponent of the logarithmic correction. In addition, the variation of the prefactor with p provides a stringent test of mode coupling theory.

Computational strategies for three-dimensional flow simulations on distributed computer systems. Ph.D. Thesis Semiannual Status Report, 15 Aug. 1993 - 15 Feb. 1994

NASA Technical Reports Server (NTRS)

Weed, Richard Allen; Sankar, L. N.

1994-01-01

An increasing amount of research activity in computational fluid dynamics has been devoted to the development of efficient algorithms for parallel computing systems. The increasing performance to price ratio of engineering workstations has led to research to development procedures for implementing a parallel computing system composed of distributed workstations. This thesis proposal outlines an ongoing research program to develop efficient strategies for performing three-dimensional flow analysis on distributed computing systems. The PVM parallel programming interface was used to modify an existing three-dimensional flow solver, the TEAM code developed by Lockheed for the Air Force, to function as a parallel flow solver on clusters of workstations. Steady flow solutions were generated for three different wing and body geometries to validate the code and evaluate code performance. The proposed research will extend the parallel code development to determine the most efficient strategies for unsteady flow simulations.

Effects of Cocos Ridge Collision on the Western Caribbean: Is there a Panama Block?

NASA Astrophysics Data System (ADS)

Kobayashi, D.; La Femina, P. C.; Geirsson, H.; Chichaco, E.; Abrego M, A. A.; Fisher, D. M.; Camacho, E. I.

2011-12-01

It has been recognized that the subduction and collision of the Cocos Ridge, a 2 km high aseismic ridge standing on >20 km thick oceanic crust of the Cocos plate, drives upper plate deformation in southern Central America. Recent studies of Global Positioning System (GPS) derived horizontal velocities relative to the Caribbean Plate showed a radial pattern centered on the Cocos Ridge axis where Cocos-Caribbean convergence is orthogonal, and margin-parallel velocities to the northwest. Models of the full three-dimensional GPS velocity field and earthquake slip vectors demonstrate low mechanical coupling along the Middle America subduction zone in Nicaragua and El Salvador, and a broad zone of high coupling beneath the Osa Peninsula, where the Cocos Ridge intersects the margin. These results suggest that Cocos Ridge collision may be the main driver for trench-parallel motion of the fore arc to the northwest and for uplift and shortening of the outer fore arc in southern Central America, whereby thickened and hence buoyant Cocos Ridge crust acts as an indenter causing the tectonic escape of the fore arc. These studies, however, were not able to constrain well the pattern of surface deformation east-southeast of the ridge axis due to a lack of GPS stations, and Cocos Ridge collision may be responsible for the kinematics and deformation of the proposed Panama block. Recent reinforcement of the GPS network in southeastern Costa Rica and Panama has increased the spatial and temporal resolution of the network and made it possible to further investigate surface deformation of southern Central America and the Panama block. We present a new regional surface velocity field for Central America from geodetic GPS data collected at 11 recently-installed and 178 existing episodic, semi-continuous, and continuous GPS sites in Nicaragua, Costa Rica, and Panama. We investigate the effects of Cocos Ridge collision on the Panama block through kinematic block modeling. Published earthquake relocation and geologic data are used to define block boundaries and fault geometries. We invert the three-dimensional GPS velocity vectors and earthquake slip vectors to estimate the magnitude and spatial distribution of interplate mechanical coupling on active plate and block boundaries around the Panama block; the Middle America Trench - South Panama Deformed Belt, the Central Costa Rican Deformed Belt, and the North Panama Deformed Belt in particular, and the rates of relative plate motion between the Panama block and the adjacent Cocos, Nazca, and Caribbean plates. This study tests whether the Panama block responds to the ridge collision as a rigid tectonic block or as a deforming zone consisting of multiple blocks.

Thermal radiation and mass transfer effects on unsteady MHD free convection flow past a vertical oscillating plate

NASA Astrophysics Data System (ADS)

Rana, B. M. Jewel; Ahmed, Rubel; Ahmmed, S. F.

2017-06-01

Unsteady MHD free convection flow past a vertical porous plate in porous medium with radiation, diffusion thermo, thermal diffusion and heat source are analyzed. The governing non-linear, partial differential equations are transformed into dimensionless by using non-dimensional quantities. Then the resultant dimensionless equations are solved numerically by applying an efficient, accurate and conditionally stable finite difference scheme of explicit type with the help of a computer programming language Compaq Visual Fortran. The stability and convergence analysis has been carried out to establish the effect of velocity, temperature, concentration, skin friction, Nusselt number, Sherwood number, stream lines and isotherms line. Finally, the effects of various parameters are presented graphically and discussed qualitatively.

Three-dimensional solutions for the thermal buckling and sensitivity derivatives of temperature-sensitive multilayered angle-ply plates

NASA Technical Reports Server (NTRS)

Noor, A. K.; Burton, W. S.

1992-01-01

Analytic three-dimensional thermoelasticity solutions are presented for the thermal buckling of multilayered angle-ply composite plates with temperature-dependent thermoelastic properties. Both the critical temperatures and the sensitivity derivatives are computed. The sensitivity derivatives measure the sensitivity of the buckling response to variations in the different lamination and material parameters of the plate. The plates are assumed to have rectangular geometry and an antisymmetric lamination with respect to the middle plane. The temperature is assumed to be independent of the surface coordinates, but has an arbitrary symmetric variation through the thickness of the plate. The prebuckling deformations are accounted for. Numerical results are presented, for plates subjected to uniform temperature increase, showing the effects of temperature-dependent material properties on the prebuckling stresses, critical temperatures, and their sensitivity derivatives.

Accuracy and predictability in use of AO three-dimensionally preformed titanium mesh plates for posttraumatic orbital reconstruction: a pilot study.

PubMed

Scolozzi, Paolo; Momjian, Armen; Heuberger, Joris; Andersen, Elene; Broome, Martin; Terzic, Andrej; Jaques, Bertrand

2009-07-01

The aim of this study was to prospectively evaluate the accuracy and predictability of new three-dimensionally preformed AO titanium mesh plates for posttraumatic orbital wall reconstruction.We analyzed the preoperative and postoperative clinical and radiologic data of 10 patients with isolated blow-out orbital fractures. Fracture locations were as follows: floor (N = 7; 70%), medial wall (N = 1; 1%), and floor/medial wall (N = 2; 2%). The floor fractures were exposed by a standard transconjunctival approach, whereas a combined transcaruncular transconjunctival approach was used in patients with medial wall fractures. A three-dimensional preformed AO titanium mesh plate (0.4 mm in thickness) was selected according to the size of the defect previously measured on the preoperative computed tomographic (CT) scan examination and fixed at the inferior orbital rim with 1 or 2 screws. The accuracy of plate positioning of the reconstructed orbit was assessed on the postoperative CT scan. Coronal CT scan slices were used to measure bony orbital volume using OsiriX Medical Image software. Reconstructed versus uninjured orbital volume were statistically correlated.Nine patients (90%) had a successful treatment outcome without complications. One patient (10%) developed a mechanical limitation of upward gaze with a resulting handicapping diplopia requiring hardware removal. Postoperative orbital CT scan showed an anatomic three-dimensional placement of the orbital mesh plates in all of the patients. Volume data of the reconstructed orbit fitted that of the contralateral uninjured orbit with accuracy to within 2.5 cm(3). There was no significant difference in volume between the reconstructed and uninjured orbits.This preliminary study has demonstrated that three-dimensionally preformed AO titanium mesh plates for posttraumatic orbital wall reconstruction results in (1) a high rate of success with an acceptable rate of major clinical complications (10%) and (2) an anatomic restoration of the bony orbital contour and volume that closely approximates that of the contralateral uninjured orbit.

Three-dimensional nanoscale imaging by plasmonic Brownian microscopy

NASA Astrophysics Data System (ADS)

Labno, Anna; Gladden, Christopher; Kim, Jeongmin; Lu, Dylan; Yin, Xiaobo; Wang, Yuan; Liu, Zhaowei; Zhang, Xiang

2017-12-01

Three-dimensional (3D) imaging at the nanoscale is a key to understanding of nanomaterials and complex systems. While scanning probe microscopy (SPM) has been the workhorse of nanoscale metrology, its slow scanning speed by a single probe tip can limit the application of SPM to wide-field imaging of 3D complex nanostructures. Both electron microscopy and optical tomography allow 3D imaging, but are limited to the use in vacuum environment due to electron scattering and to optical resolution in micron scales, respectively. Here we demonstrate plasmonic Brownian microscopy (PBM) as a way to improve the imaging speed of SPM. Unlike photonic force microscopy where a single trapped particle is used for a serial scanning, PBM utilizes a massive number of plasmonic nanoparticles (NPs) under Brownian diffusion in solution to scan in parallel around the unlabeled sample object. The motion of NPs under an evanescent field is three-dimensionally localized to reconstruct the super-resolution topology of 3D dielectric objects. Our method allows high throughput imaging of complex 3D structures over a large field of view, even with internal structures such as cavities that cannot be accessed by conventional mechanical tips in SPM.

Method of manufacturing lightweight thermo-barrier material

NASA Technical Reports Server (NTRS)

Blair, Winford (Inventor)

1987-01-01

A method of manufacturing thermal barrier structures comprising at least three dimpled cores separated by flat plate material with the outer surface of the flat plate material joined together by diffusion bonding.

Numerical aspects and implementation of a two-layer zonal wall model for LES of compressible turbulent flows on unstructured meshes

NASA Astrophysics Data System (ADS)

Park, George Ilhwan; Moin, Parviz

2016-01-01

This paper focuses on numerical and practical aspects associated with a parallel implementation of a two-layer zonal wall model for large-eddy simulation (LES) of compressible wall-bounded turbulent flows on unstructured meshes. A zonal wall model based on the solution of unsteady three-dimensional Reynolds-averaged Navier-Stokes (RANS) equations on a separate near-wall grid is implemented in an unstructured, cell-centered finite-volume LES solver. The main challenge in its implementation is to couple two parallel, unstructured flow solvers for efficient boundary data communication and simultaneous time integrations. A coupling strategy with good load balancing and low processors underutilization is identified. Face mapping and interpolation procedures at the coupling interface are explained in detail. The method of manufactured solution is used for verifying the correct implementation of solver coupling, and parallel performance of the combined wall-modeled LES (WMLES) solver is investigated. The method has successfully been applied to several attached and separated flows, including a transitional flow over a flat plate and a separated flow over an airfoil at an angle of attack.

Parallel computation of three-dimensional aeroelastic fluid-structure interaction

NASA Astrophysics Data System (ADS)

Sadeghi, Mani

This dissertation presents a numerical method for the parallel computation of aeroelasticity (ParCAE). A flow solver is coupled to a structural solver by use of a fluid-structure interface method. The integration of the three-dimensional unsteady Navier-Stokes equations is performed in the time domain, simultaneously to the integration of a modal three-dimensional structural model. The flow solution is accelerated by using a multigrid method and a parallel multiblock approach. Fluid-structure coupling is achieved by subiteration. A grid-deformation algorithm is developed to interpolate the deformation of the structural boundaries onto the flow grid. The code is formulated to allow application to general, three-dimensional, complex configurations with multiple independent structures. Computational results are presented for various configurations, such as turbomachinery blade rows and aircraft wings. Investigations are performed on vortex-induced vibrations, effects of cascade mistuning on flutter, and cases of nonlinear cascade and wing flutter.

Synchronous parallel spatially resolved stochastic cluster dynamics

DOE PAGES

Dunn, Aaron; Dingreville, Rémi; Martínez, Enrique; ...

2016-04-23

In this work, a spatially resolved stochastic cluster dynamics (SRSCD) model for radiation damage accumulation in metals is implemented using a synchronous parallel kinetic Monte Carlo algorithm. The parallel algorithm is shown to significantly increase the size of representative volumes achievable in SRSCD simulations of radiation damage accumulation. Additionally, weak scaling performance of the method is tested in two cases: (1) an idealized case of Frenkel pair diffusion and annihilation, and (2) a characteristic example problem including defect cluster formation and growth in α-Fe. For the latter case, weak scaling is tested using both Frenkel pair and displacement cascade damage.more » To improve scaling of simulations with cascade damage, an explicit cascade implantation scheme is developed for cases in which fast-moving defects are created in displacement cascades. For the first time, simulation of radiation damage accumulation in nanopolycrystals can be achieved with a three dimensional rendition of the microstructure, allowing demonstration of the effect of grain size on defect accumulation in Frenkel pair-irradiated α-Fe.« less

The novel implicit LU-SGS parallel iterative method based on the diffusion equation of a nuclear reactor on a GPU cluster

NASA Astrophysics Data System (ADS)

Zhang, Jilin; Sha, Chaoqun; Wu, Yusen; Wan, Jian; Zhou, Li; Ren, Yongjian; Si, Huayou; Yin, Yuyu; Jing, Ya

2017-02-01

GPU not only is used in the field of graphic technology but also has been widely used in areas needing a large number of numerical calculations. In the energy industry, because of low carbon, high energy density, high duration and other characteristics, the development of nuclear energy cannot easily be replaced by other energy sources. Management of core fuel is one of the major areas of concern in a nuclear power plant, and it is directly related to the economic benefits and cost of nuclear power. The large-scale reactor core expansion equation is large and complicated, so the calculation of the diffusion equation is crucial in the core fuel management process. In this paper, we use CUDA programming technology on a GPU cluster to run the LU-SGS parallel iterative calculation against the background of the diffusion equation of the reactor. We divide one-dimensional and two-dimensional mesh into a plurality of domains, with each domain evenly distributed on the GPU blocks. A parallel collision scheme is put forward that defines the virtual boundary of the grid exchange information and data transmission by non-stop collision. Compared with the serial program, the experiment shows that GPU greatly improves the efficiency of program execution and verifies that GPU is playing a much more important role in the field of numerical calculations.

Further two-dimensional code development for Stirling space engine components

NASA Technical Reports Server (NTRS)

Ibrahim, Mounir; Tew, Roy C.; Dudenhoefer, James E.

1990-01-01

The development of multidimensional models of Stirling engine components is described. Two-dimensional parallel plate models of an engine regenerator and a cooler were used to study heat transfer under conditions of laminar, incompressible oscillating flow. Substantial differences in the nature of the temperature variations in time over the cycle were observed for the cooler as contrasted with the regenerator. When the two-dimensional cooler model was used to calculate a heat transfer coefficient, it yields a very different result from that calculated using steady-flow correlations. Simulation results for the regenerator and the cooler are presented.

Cross-stream diffusion under pressure-driven flow in microchannels with arbitrary aspect ratios: a phase diagram study using a three-dimensional analytical model

PubMed Central

Song, Hongjun; Wang, Yi; Pant, Kapil

2011-01-01

This article presents a three-dimensional analytical model to investigate cross-stream diffusion transport in rectangular microchannels with arbitrary aspect ratios under pressure-driven flow. The Fourier series solution to the three-dimensional convection–diffusion equation is obtained using a double integral transformation method and associated eigensystem calculation. A phase diagram derived from the dimensional analysis is presented to thoroughly interrogate the characteristics in various transport regimes and examine the validity of the model. The analytical model is verified against both experimental and numerical models in terms of the concentration profile, diffusion scaling law, and mixing efficiency with excellent agreement (with <0.5% relative error). Quantitative comparison against other prior analytical models in extensive parameter space is also performed, which demonstrates that the present model accommodates much broader transport regimes with significantly enhanced applicability. PMID:22247719

Cross-stream diffusion under pressure-driven flow in microchannels with arbitrary aspect ratios: a phase diagram study using a three-dimensional analytical model.

PubMed

Song, Hongjun; Wang, Yi; Pant, Kapil

2012-01-01

This article presents a three-dimensional analytical model to investigate cross-stream diffusion transport in rectangular microchannels with arbitrary aspect ratios under pressure-driven flow. The Fourier series solution to the three-dimensional convection-diffusion equation is obtained using a double integral transformation method and associated eigensystem calculation. A phase diagram derived from the dimensional analysis is presented to thoroughly interrogate the characteristics in various transport regimes and examine the validity of the model. The analytical model is verified against both experimental and numerical models in terms of the concentration profile, diffusion scaling law, and mixing efficiency with excellent agreement (with <0.5% relative error). Quantitative comparison against other prior analytical models in extensive parameter space is also performed, which demonstrates that the present model accommodates much broader transport regimes with significantly enhanced applicability.

Rapid prototyping to design a customized locking plate for pancarpal arthrodesis in a giant breed dog.

PubMed

Petazzoni, M; Nicetto, T

2014-01-01

This report describes the treatment of traumatic carpal hyperextension in a giant breed dog by pancarpal arthrodesis using a custom-made Fixin locking plate, created with the aid of a three-dimensional plastic model of the bones of the antebrachium produced by rapid prototyping technology. A three-year-old 104 kg male Mastiff dog was admitted for treatment of carpal hyperextension injury. After diagnosis of carpal instability, surgery was recommended. Computed tomography images were used to create a life-size three-dimensional plastic model of the forelimb. The model was used as the basis for constructing a customized 12-hole Fixin locking plate. The plate was used to attain successful pancarpal arthrodesis in the animal. Radiographic examination after 74 and 140 days revealed signs of osseous union of the arthrodesis. Further clinical and radiographic follow-up examination three years later did not reveal any changes in implant position or complications.

A three-dimensional spectral algorithm for simulations of transition and turbulence

NASA Technical Reports Server (NTRS)

Zang, T. A.; Hussaini, M. Y.

1985-01-01

A spectral algorithm for simulating three dimensional, incompressible, parallel shear flows is described. It applies to the channel, to the parallel boundary layer, and to other shear flows with one wall bounded and two periodic directions. Representative applications to the channel and to the heated boundary layer are presented.

Global Search of a Three-dimensional Low Solidity Circular Cascade Diffuser for Centrifugal Blowers by Meta-model Assisted Optimization

NASA Astrophysics Data System (ADS)

Sakaguchi, Daisaku; Sakue, Daiki; Tun, Min Thaw

2018-04-01

A three-dimensional blade of a low solidity circular cascade diffuser in centrifugal blowers is designed by means of a multi-point optimization technique. The optimization aims at improving static pressure coefficient at a design point and at a small flow rate condition. Moreover, a clear definition of secondary flow expressed by positive radial velocity at hub side is taken into consideration in constraints. The number of design parameters for three-dimensional blade reaches to 10 in this study, such as a radial gap, a radial chord length and mean camber angle distribution of the LSD blade with five control points, control point between hub and shroud with two design freedom. Optimization results show clear Pareto front and selected optimum design shows good improvement of pressure rise in diffuser at small flow rate conditions. It is found that three-dimensional blade has advantage to stabilize the secondary flow effect with improving pressure recovery of the low solidity circular cascade diffuser.

Electro-osmotic flow in coated nanocapillaries: a theoretical investigation.

PubMed

Marini Bettolo Marconi, Umberto; Monteferrante, Michele; Melchionna, Simone

2014-12-14

Motivated by recent experiments, we present a theoretical investigation of how the electro-osmotic flow occurring in a capillary is modified when its charged surfaces are coated with charged polymers. The theoretical treatment is based on a three-dimensional model consisting of a ternary fluid-mixture, representing the solvent and two species for the ions, confined between two parallel charged plates decorated with a fixed array of scatterers representing the polymer coating. The electro-osmotic flow, generated by a constant electric field applied in a direction parallel to the plates, is studied numerically by means of Lattice Boltzmann simulations. In order to gain further understanding we performed a simple theoretical analysis by extending the Stokes-Smoluchowski equation to take into account the porosity induced by the polymers in the region adjacent to the walls. We discuss the nature of the velocity profiles by focusing on the competing effects of the polymer charges and the frictional forces they exert. We show evidence of the flow reduction and of the flow inversion phenomenon when the polymer charge is opposite to the surface charge. By using the density of polymers and the surface charge as control variables, we propose a phase diagram that discriminates the direct and the reversed flow regimes and determines their dependence on the ionic concentration.

Generation of plate tectonics via grain-damage and pinning

NASA Astrophysics Data System (ADS)

Bercovici, D.; Ricard, Y. R.

2012-12-01

Weakening and shear localization in the lithosphere are essential ingredients for understanding how and whether plate tectonics is generated from mantle convection on terrestrial planets. The grain-damage and pinning mechanism of Bercovici & Ricard (2012) for lithospheric shear--localization proposes that damage to the interface between phases in a polycrystalline material like peridotite (composed primarily of olivine and pyroxene) increases the number of small Zener pinning surfaces that constrain mineral grains to ever smaller sizes regardless of creep mechanism. This effect allows a self-softening feedback in which damage and grain-reduction can co-exist with a grain-size dependent diffusion creep rheology; moreoever, grain growth and weak-zone healing are greatly impeded by Zener pinning thereby leading to long-lived relic weak zones. This mechanism is employed in two-dimensional flow calculations to test its ability to generate toroidal (strike-slip) motion from convective type flow and to influence plate evolution. The fluid dynamical calculations employ source-sink driven flow as a proxy for convective poloidal flow (upwelling/downwelling and divergent/convergent motion), and the coupling of this flow with non-linear rheological mechanisms excites toroidal or strike-slip motion. The numerical experiments show that pure dislocation-creep rheology, and grain-damage without Zener pinning (as occurs in a single-phase assemblages) permit only weak localization and toroidal flow; however, the full grain-damage with pinning readily allows focussed localization and intense, plate-like toroidal motion and strike-slip deformation. Rapid plate motion changes are also tested with abrupt rotations of the source-sink field after a plate-like configuration is developed; the post-rotation flow and material property fields are found to never recover or lose memory of the original configuration, leading to suboptimally aligned plate boundaries (e.g., strike-slip margins non-parallel to plate motion), oblique subduction and highly localized, weak and long lived acute plate-boundary junctions such as at the Aleution-Kurile intersection. The grain-damage and pinning theory therefore readily satisfies key plate-tectonic metrics of localized toroidal motion and plate-boundary inheritance, and thus provides a predictive theory for the generation of plate tectonics on Earth and other planets. References: Bercovici, D., Ricard, Y., 2012. Mechanisms for the generation of plate tectonics by two-phase grain-damage and pinning. Phys. Earth Planet. Int. 202-203, 27--55.

Rectification of depth measurement using pulsed thermography with logarithmic peak second derivative method

NASA Astrophysics Data System (ADS)

Li, Xiaoli; Zeng, Zhi; Shen, Jingling; Zhang, Cunlin; Zhao, Yuejin

2018-03-01

Logarithmic peak second derivative (LPSD) method is the most popular method for depth prediction in pulsed thermography. It is widely accepted that this method is independent of defect size. The theoretical model for LPSD method is based on the one-dimensional solution of heat conduction without considering the effect of defect size. When a decay term considering defect aspect ratio is introduced into the solution to correct the three-dimensional thermal diffusion effect, we found that LPSD method is affected by defect size by analytical model. Furthermore, we constructed the relation between the characteristic time of LPSD method and defect aspect ratio, which was verified with the experimental results of stainless steel and glass fiber reinforced plate (GFRP) samples. We also proposed an improved LPSD method for depth prediction when the effect of defect size was considered, and the rectification results of stainless steel and GFRP samples were presented and discussed.

A transition in the viscous fingering instability in miscible fluids

NASA Astrophysics Data System (ADS)

Videbaek, Thomas; Nagel, Sidney R.

2017-11-01

The viscous fingering instability in a quasi-two dimensional Hele-Shaw cell is an example of complex structure formation from benign initial conditions. When the invading fluid has the lesser viscosity, the interface between the two fluids is unstable to finger formation. Here, we study the instability between pairs of miscible fluids in a circular cell with fluid injected at its center. As the injection rate is decreased, diffusion will smooth out the discontinuity in the gap-averaged viscosity at the interface between the fluids. At high injection rates (i.e., high Péclet number, Pe), fingering is associated with three-dimensional structure within the gap between the confining plates. On lowering Pe, we find a sharp transition in the finger morphology at a critical value, Pec (ηi /ηo) 1 / 2 , with ηi (ηo) being the viscosity of the inner (outer) fluid; at this point, the width of the fingers jumps, the length of the fingers shrinks towards zero and the three-dimensional structure goes from half filling to fully filling the gap. Thus, by controlling the viscosity contrast at the interface, one can alter and even completely suppress the instability.

Electroless plated maghemite for three-dimensional magneto photonic crystals

NASA Astrophysics Data System (ADS)

Mito, Shinichiro; Kawashima, Takuya; Kawaguchi, Takuma; Sasano, Junji; Takagi, Hiroyuki; Inoue, Mitsuteru

2017-05-01

Three-dimensional magneto photonic crystals (3D-MPCs) are promising material for manipulating light in 3D space. In this study, we fabricated 3D-MPC that is filling the air-gap of opal photonic crystal with magnetic material by electroless plating. The electroless plating is an attractive film-forming method which provides magnetic material films on various substrates in aqueous solution at 24-90 °C. As magnetic material for filling the air-gap, maghemite (γ-Fe2O3) film was plated in opal photonic crystal. The plated maghemite film showed a Faraday rotation of 0.6 deg./μm at 440 nm and significantly lower absorption than magnetite. The plated opal showed photonic band gap and magneto-optic response. Faraday rotation of the plated opal was enhanced at the band edge. The photonic band gap and the Faraday rotation spectra were changed as a function of incident angle of light. Electroless plating of maghemite could be promising technique for fabricating 3D-MPCs.

Unsteady Separated Flows: Vorticity and Turbulence.

DTIC Science & Technology

1987-04-06

plate, the results are somewhat different . A vortex initiated before : max is obtained in the oscillation cycle yielded convection velocities not...in flat plate m resulted in a 6.25% advance in the cycle where the leading edge vortex was initiated; a value close to that measured using the NACA...three-dimensional model we have used to initiate the three- dimensional study of unsteady flows is a symmetric airfoil (NACA 0015) section fitted witL, a

Three-Dimensional Thermal Boundary Layer Corrections for Circular Heat Flux Gauges Mounted in a Flat Plate with a Surface Temperature Discontinuity

NASA Technical Reports Server (NTRS)

Kandula, M.; Haddad, G. F.; Chen, R.-H.

2006-01-01

Three-dimensional Navier-Stokes computational fluid dynamics (CFD) analysis has been performed in an effort to determine thermal boundary layer correction factors for circular convective heat flux gauges (such as Schmidt-Boelter and plug type)mounted flush in a flat plate subjected to a stepwise surface temperature discontinuity. Turbulent flow solutions with temperature-dependent properties are obtained for a free stream Reynolds number of 1E6, and freestream Mach numbers of 2 and 4. The effect of gauge diameter and the plate surface temperature have been investigated. The 3-D CFD results for the heat flux correction factors are compared to quasi-21) results deduced from constant property integral solutions and also 2-D CFD analysis with both constant and variable properties. The role of three-dimensionality and of property variations on the heat flux correction factors has been demonstrated.

Hydroelastic behaviour of a structure exposed to an underwater explosion.

PubMed

Colicchio, G; Greco, M; Brocchini, M; Faltinsen, O M

2015-01-28

The hydroelastic interaction between an underwater explosion and an elastic plate is investigated num- erically through a domain-decomposition strategy. The three-dimensional features of the problem require a large computational effort, which is reduced through a weak coupling between a one-dimensional radial blast solver, which resolves the blast evolution far from the boundaries, and a three-dimensional compressible flow solver used where the interactions between the compression wave and the boundaries take place and the flow becomes three-dimensional. The three-dimensional flow solver at the boundaries is directly coupled with a modal structural solver that models the response of the solid boundaries like elastic plates. This enables one to simulate the fluid-structure interaction as a strong coupling, in order to capture hydroelastic effects. The method has been applied to the experimental case of Hung et al. (2005 Int. J. Impact Eng. 31, 151-168 (doi:10.1016/j.ijimpeng.2003.10.039)) with explosion and structure sufficiently far from other boundaries and successfully validated in terms of the evolution of the acceleration induced on the plate. It was also used to investigate the interaction of an underwater explosion with the bottom of a close-by ship modelled as an orthotropic plate. In the application, the acoustic phase of the fluid-structure interaction is examined, highlighting the need of the fluid-structure coupling to capture correctly the possible inception of cavitation. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Hydrodynamics of a three-dimensional self-propelled flexible plate

NASA Astrophysics Data System (ADS)

Ryu, Jaeha; Sung, Hyung Jin

2017-11-01

A three-dimensional self-propelled flexible plate in a quiescent flow was simulated using the immersed boundary method. The clamped leading edge of the flexible plate was forced into a vertical oscillation, while free to move horizontally. To reveal the hydrodynamics of the plate, the averaged cruising speed (UC) , the input power (P) , and the swimming efficiency (η) were analyzed as a function of the bending rigidity (γ) and the flapping frequency (f) . The velocity field around the plate and the exerted force on the plate were demonstrated to find out the dynamic interaction between the plate and the surrounding fluid. The kinematics of the plate, the maximum angle of attack (ϕmax) , and the mean effective length (Leff) were examined accounting for the hydrodynamics of the self-propelled flexible plate. The vortical structures around the plate were visualized, and the influence of the tip vortex on the swimming efficiency was explored qualitatively and quantitatively. This work was supported by the Creative Research Initiatives (No. 2017-013369) program of the National Research Foundation of Korea (MSIP).

Bistatic scattering from a three-dimensional object above a two-dimensional randomly rough surface modeled with the parallel FDTD approach.

PubMed

Guo, L-X; Li, J; Zeng, H

2009-11-01

We present an investigation of the electromagnetic scattering from a three-dimensional (3-D) object above a two-dimensional (2-D) randomly rough surface. A Message Passing Interface-based parallel finite-difference time-domain (FDTD) approach is used, and the uniaxial perfectly matched layer (UPML) medium is adopted for truncation of the FDTD lattices, in which the finite-difference equations can be used for the total computation domain by properly choosing the uniaxial parameters. This makes the parallel FDTD algorithm easier to implement. The parallel performance with different number of processors is illustrated for one rough surface realization and shows that the computation time of our parallel FDTD algorithm is dramatically reduced relative to a single-processor implementation. Finally, the composite scattering coefficients versus scattered and azimuthal angle are presented and analyzed for different conditions, including the surface roughness, the dielectric constants, the polarization, and the size of the 3-D object.

Nonequilibrium fluctuations during diffusion in liquid layers

NASA Astrophysics Data System (ADS)

Brogioli, Doriano; Vailati, Alberto

2017-07-01

Theoretical analysis and experiments have provided compelling evidence of the presence of long-range nonequilibrium concentration fluctuations during diffusion processes in fluids. In this paper, we investigate the dependence of the features of the fluctuations from the dimensionality of the system. In three-dimensional fluids the amplitude of nonequilibrium fluctuations can become several orders of magnitude larger than that of equilibrium fluctuations. Notwithstanding that, the amplitude of nonequilibrium fluctuations remains small with respect to the concentration difference driving the diffusion process. By extending the theory to two-dimensional systems, such as liquid monolayers and bilayers, we show that the amplitude of the fluctuations becomes much stronger than in three-dimensional systems. We investigate the properties of the fronts of diffusion and show that they have a self-affine structure characterized by a Hurst exponent H =1 . We discuss the implications of these results for diffusion in liquid crystals and in cellular membranes of living organisms.

Nonequilibrium fluctuations during diffusion in liquid layers.

PubMed

Brogioli, Doriano; Vailati, Alberto

2017-07-01

Theoretical analysis and experiments have provided compelling evidence of the presence of long-range nonequilibrium concentration fluctuations during diffusion processes in fluids. In this paper, we investigate the dependence of the features of the fluctuations from the dimensionality of the system. In three-dimensional fluids the amplitude of nonequilibrium fluctuations can become several orders of magnitude larger than that of equilibrium fluctuations. Notwithstanding that, the amplitude of nonequilibrium fluctuations remains small with respect to the concentration difference driving the diffusion process. By extending the theory to two-dimensional systems, such as liquid monolayers and bilayers, we show that the amplitude of the fluctuations becomes much stronger than in three-dimensional systems. We investigate the properties of the fronts of diffusion and show that they have a self-affine structure characterized by a Hurst exponent H=1. We discuss the implications of these results for diffusion in liquid crystals and in cellular membranes of living organisms.

Scalar Casimir densities and forces for parallel plates in cosmic string spacetime

NASA Astrophysics Data System (ADS)

Bezerra de Mello, E. R.; Saharian, A. A.; Abajyan, S. V.

2018-04-01

We analyze the Green function, the Casimir densities and forces associated with a massive scalar quantum field confined between two parallel plates in a higher dimensional cosmic string spacetime. The plates are placed orthogonal to the string, and the field obeys the Robin boundary conditions on them. The boundary-induced contributions are explicitly extracted in the vacuum expectation values (VEVs) of the field squared and of the energy-momentum tensor for both the single plate and two plates geometries. The VEV of the energy-momentum tensor, in additional to the diagonal components, contains an off diagonal component corresponding to the shear stress. The latter vanishes on the plates in special cases of Dirichlet and Neumann boundary conditions. For points outside the string core the topological contributions in the VEVs are finite on the plates. Near the string the VEVs are dominated by the boundary-free part, whereas at large distances the boundary-induced contributions dominate. Due to the nonzero off diagonal component of the vacuum energy-momentum tensor, in addition to the normal component, the Casimir forces have nonzero component parallel to the boundary (shear force). Unlike the problem on the Minkowski bulk, the normal forces acting on the separate plates, in general, do not coincide if the corresponding Robin coefficients are different. Another difference is that in the presence of the cosmic string the Casimir forces for Dirichlet and Neumann boundary conditions differ. For Dirichlet boundary condition the normal Casimir force does not depend on the curvature coupling parameter. This is not the case for other boundary conditions. A new qualitative feature induced by the cosmic string is the appearance of the shear stress acting on the plates. The corresponding force is directed along the radial coordinate and vanishes for Dirichlet and Neumann boundary conditions. Depending on the parameters of the problem, the radial component of the shear force can be either positive or negative.

Numerical modeling of the Indo-Australian intraplate deformation

NASA Astrophysics Data System (ADS)

Brandon, Vincent; Royer, Jean-Yves

2014-05-01

The Indo-Australian plate is perhaps the best example of wide intraplate deformation within an oceanic plate. The deformation is expressed by an unusual level of intraplate seismicity, including magnitude Mw > 8 events, large-scale folding and deep faulting of the oceanic lithosphere and reactivation of extinct fracture zones. The deformation pattern and kinematic data inversions suggest that the Indo-Australian plate can be viewed as a composite plate made of three rigid component plates - India, Capricorn, Australia - separated by wide and diffuse boundaries undergoing either extensional or compressional deformation. We tested this model using the SHELLS numerical code (Kong & Bird, 1995). The Indo-Australian plate is modeled by a mesh of 5281 spherical triangular finite elements. Mesh edges parallel the major extinct fracture zones so that they can be reactivated by reducing their friction rates. Strength of the plate is defined by the age of the lithosphere and seafloor topography. Model boundary conditions are only defined by the plate velocities predicted by the rotation vectors between rigid components of the Indo-Australian plate and their neighboring plates. Since the mesh limits all belong to rigid plates with fully defined Euler vectors, no conditions are imposed on the location, extent and limits of the diffuse and deforming zones. Using MORVEL plate velocities (DeMets et al., 2010), predicted deformation patterns are very consistent with that observed. Pre-existing structures of the lithosphere play an important role in the intraplate deformation and its distribution. The Chagos Bank focuses most of the extensional deformation between the Indian and Capricorn plates. Agreement between models and observation improves by weakening fossil fracture zones relative to the surrounding crust; however only limited sections of FZ's accommodate deformation. The reactivation of the Eocene FZ's in the Central Indian Basin (CIB) and Wharton Basin (WB) explains the drastic change in the deformation style between these basins across the Ninetyeast ridge. The highest slip rates along the WB FZ's are predicted where two major strike-slip faulting earthquakes occurred in April 2012 (Mw=8.6 and 8.2). The best model is obtained when adding a local HF anomaly in the center of the CIB (proxy for weakening the lithospheric strength), consistent with evidence of mantle serpentinization in the CIB where deep seismics image a series of N-S dipping thrust faults reaching Moho depths. The rates of extension or shortening, inferred from the predicted strain rates, are consistent with previous estimates based on different approaches. This finite element modeling confirms that oceanic lithosphere, like the continental lithosphere, can slowly deform over very broad areas (> 1000 x 1000 km).

Uniform electric field generation in circular multi-well culture plates using polymeric inserts

NASA Astrophysics Data System (ADS)

Tsai, Hsieh-Fu; Cheng, Ji-Yen; Chang, Hui-Fang; Yamamoto, Tadashi; Shen, Amy Q.

2016-05-01

Applying uniform electric field (EF) in vitro in the physiological range has been achieved in rectangular shaped microchannels. However, in a circular-shaped device, it is difficult to create uniform EF from two electric potentials due to different electrical resistances originated from the length difference between the diameter of the circle and the length of any parallel chord of the bottom circular chamber where cells are cultured. To address this challenge, we develop a three-dimensional (3D) computer-aided designed (CAD) polymeric insert to create uniform EF in circular shaped multi-well culture plates. A uniform EF with a coefficient of variation (CV) of 1.2% in the 6-well plate can be generated with an effective stimulation area percentage of 69.5%. In particular, NIH/3T3 mouse embryonic fibroblast cells are used to validate the performance of the 3D designed Poly(methyl methacrylate) (PMMA) inserts in a circular-shaped 6-well plate. The CAD based inserts can be easily scaled up (i.e., 100 mm dishes) to further increase effective stimulation area percentages, and also be implemented in commercially available cultureware for a wide variety of EF-related research such as EF-cell interaction and tissue regeneration studies.

Viscous, resistive MHD stability computed by spectral techniques

NASA Technical Reports Server (NTRS)

Dahlburg, R. B.; Zang, T. A.; Montgomery, D.; Hussaini, M. Y.

1983-01-01

Expansions in Chebyshev polynomials are used to study the linear stability of one dimensional magnetohydrodynamic (MHD) quasi-equilibria, in the presence of finite resistivity and viscosity. The method is modeled on the one used by Orszag in accurate computation of solutions of the Orr-Sommerfeld equation. Two Reynolds like numbers involving Alfven speeds, length scales, kinematic viscosity, and magnetic diffusivity govern the stability boundaries, which are determined by the geometric mean of the two Reynolds like numbers. Marginal stability curves, growth rates versus Reynolds like numbers, and growth rates versus parallel wave numbers are exhibited. A numerical result which appears general is that instability was found to be associated with inflection points in the current profile, though no general analytical proof has emerged. It is possible that nonlinear subcritical three dimensional instabilities may exist, similar to those in Poiseuille and Couette flow.

Magnetorheological effect in the magnetic field oriented along the vorticity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuzhir, P., E-mail: pavel.kuzhir@unice.fr; Magnet, C.; Fezai, H.

2014-11-01

In this work, we have studied the magnetorheological (MR) fluid rheology in the magnetic field parallel to the fluid vorticity. Experimentally, the MR fluid flow was realized in the Couette coaxial cylinder geometry with the magnetic field parallel to the symmetry axis. The rheological measurements were compared to those obtained in the cone-plate geometry with the magnetic field perpendicular to the lower rheometer plate. Experiments revealed a quasi-Bingham behavior in both geometries with the stress level being just a few dozens of percent smaller in the Couette cylindrical geometry at the same internal magnetic field. The unexpectedly high MR responsemore » in the magnetic field parallel to the fluid vorticity is explained by stochastic fluctuations of positions and orientations of the particle aggregates. These fluctuations are induced by magnetic interactions between them. Once misaligned from the vorticity direction, the aggregates generate a high stress independent of the shear rate, and thus assimilated to the suspension apparent (dynamic) yield stress. Quantitatively, the fluctuations of the aggregate orientation are modeled as a rotary diffusion process with a diffusion constant proportional to the mean square interaction torque. The model gives a satisfactory agreement with the experimental field dependency of the apparent yield stress and confirms the nearly quadratic concentration dependency σ{sub Y}∝Φ{sup 2.2}, revealed in experiments. The practical interest of this study lies in the development of MR smart devices with the magnetic field nonperpendicular to the channel walls.« less

Convection with a simple chemically reactive passive scalar

NASA Astrophysics Data System (ADS)

Herring, J. R.; Wyngaard, J. C.

Convection between horizontal stress-free perfectly conducting plates is examined in the turbulent regime for air. Results are presented for an additional scalar undergoing simple linear decay. We discuss qualitative aspects of the flow in terms of spectral and three-dimensional contour maps of the velocity and scalar fields. The horizontal mean profiles of scalar gradients and fluxes agree rather well with simple mixing-length concepts. Further, the mean profiles for a range of the destruction-rate parameter are shown to be nearly completely characterized by the boundary fluxes. Finally, we shall use the present numerical data as a basis for exploring a generalization of eddy-diffusion concepts so as to properly incorporate non-local effects.

Three point lead screw positioning apparatus for a cavity tuning plate

NASA Technical Reports Server (NTRS)

Calco, Frank S. (Inventor)

1993-01-01

Three lead screws are provided for adjusting the position of a traversing plate. Each of the three lead screws is threaded through a collar that is press fitted through the center of one of three pinion gears. A sun gear meshes with all three pinion gears and transversely moves the three lead screws upon actuation of a drive gear. The drive gear meshes with the sun gear and is driven by a handle or servomotor. When the handle or servomotor rotates the drive gear, the sun gear rotates causing the three pinion gears to rotate, thus, causing transverse movement of the three lead screws and, accordingly, transverse movement of the transversing plate. When the drive gear rotates, the traversing plate is driven in and out of a microwave cavity. Thus, the length or size of the cavity can be tuned while maintaining the traversing plate in an exact parallel relationship with an opposing plate on another end of the cavity.

Three point lead screw positioning apparatus for a cavity tuning plate

NASA Astrophysics Data System (ADS)

Calco, Frank S.

1993-09-01

Three lead screws are provided for adjusting the position of a traversing plate. Each of the three lead screws is threaded through a collar that is press fitted through the center of one of three pinion gears. A sun gear meshes with all three pinion gears and transversely moves the three lead screws upon actuation of a drive gear. The drive gear meshes with the sun gear and is driven by a handle or servomotor. When the handle or servomotor rotates the drive gear, the sun gear rotates causing the three pinion gears to rotate, thus, causing transverse movement of the three lead screws and, accordingly, transverse movement of the transversing plate. When the drive gear rotates, the traversing plate is driven in and out of a microwave cavity. Thus, the length or size of the cavity can be tuned while maintaining the traversing plate in an exact parallel relationship with an opposing plate on another end of the cavity.

An experimental study of multiple jet mixing

NASA Technical Reports Server (NTRS)

Krothapalli, D.; Baganoff, D.; Karamcheti, K.

1979-01-01

Measurements of an incompressible jet issuing from an array of rectangular lobes, equally spaced with their small dimensions in a line, both as a free jet, and as a confined jet, are carried out in three parts: (1) on a single rectangular free jet, (2) on the same jet in a multiple free jet configuration, and (3) on the same jet in a multiple jet configuration with confining surfaces (two parallel plates are symmetrically placed perpendicular to the long dimension of each lobe covering the entire flow field under consideration). In the case of a single rectangular free jet, the flow field of the jet is characterized by the presence of three distinct regions in the axial mean velocity decay and are referred to as: potential core region, two dimensional type region, and axisymmetric type region. In the case of a multiple free jet, the flow field for downstream distance X greater than 60D (D = width of a lobe) resembles that of a jet exiting from a two dimensional nozzle with its short dimension being the long dimension of the lobe.

Selective electroless plating of 3D-printed plastic structures for three-dimensional microwave metamaterials

NASA Astrophysics Data System (ADS)

Ishikawa, Atsushi; Kato, Taiki; Takeyasu, Nobuyuki; Fujimori, Kazuhiro; Tsuruta, Kenji

2017-10-01

A technique of selective electroless plating onto PLA-ABS (Polylactic Acid-Acrylonitrile Butadiene Styrene) composite structures fabricated by three-dimensional (3D) printing is demonstrated to construct 3D microwave metamaterials. The reducing activity of the PLA surface is selectively enhanced by the chemical modification involving Sn2+ in a simple wet process, thereby forming a highly conductive Ag-plated membrane only onto the PLA surface. The fabricated metamaterial composed of Ag-plated PLA and non-plated ABS parts is characterized experimentally and numerically to demonstrate the important bi-anisotropic microwave responses arising from the 3D nature of metallodielectric structures. Our approach based on a simple wet chemical process allows for the creation of highly complex 3D metal-insulator structures, thus paving the way toward the sophisticated microwave applications of the 3D printing technology.

Fracture Mechanics of Thin, Cracked Plates Under Tension, Bending and Out-of-Plane Shear Loading

NASA Technical Reports Server (NTRS)

Zehnder, Alan T.; Hui, C. Y.; Potdar, Yogesh; Zucchini, Alberto

1999-01-01

Cracks in the skin of aircraft fuselages or other shell structures can be subjected to very complex stress states, resulting in mixed-mode fracture conditions. For example, a crack running along a stringer in a pressurized fuselage will be subject to the usual in-plane tension stresses (Mode-I) along with out-of-plane tearing stresses (Mode-III like). Crack growth and initiation in this case is correlated not only with the tensile or Mode-I stress intensity factor, K(sub I), but depends on a combination of parameters and on the history of crack growth. The stresses at the tip of a crack in a plate or shell are typically described in terms of either the small deflection Kirchhoff plate theory. However, real applications involve large deflections. We show, using the von-Karman theory, that the crack tip stress field derived on the basis of the small deflection theory is still valid for large deflections. We then give examples demonstrating the exact calculation of energy release rates and stress intensity factors for cracked plates loaded to large deflections. The crack tip fields calculated using the plate theories are an approximation to the actual three dimensional fields. Using three dimensional finite element analyses we have explored the relationship between the three dimensional elasticity theory and two dimensional plate theory results. The results show that for out-of-plane shear loading the three dimensional and Kirchhoff theory results coincide at distance greater than h/2 from the crack tip, where h/2 is the plate thickness. Inside this region, the distribution of stresses through the thickness can be very different from the plate theory predictions. We have also explored how the energy release rate varies as a function of crack length to plate thickness using the different theories. This is important in the implementation of fracture prediction methods using finite element analysis. Our experiments show that under certain conditions, during fatigue crack growth, the presence of out-of-plane shear loads induces a great deal of contact and friction on the crack surfaces, dramatically reducing crack growth rate. A series of experiments and a proposed computational approach for accounting for the friction is discussed.

Inverse design of centrifugal compressor vaned diffusers in inlet shear flows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zangeneh, M.

1996-04-01

A three-dimensional inverse design method in which the blade (or vane) geometry is designed for specified distributions of circulation and blade thickness is applied to the design of centrifugal compressor vaned diffusers. Two generic diffusers are designed, one with uniform inlet flow (equivalent to a conventional design) and the other with a sheared inlet flow. The inlet shear flow effects are modeled in the design method by using the so-called ``Secondary Flow Approximation`` in which the Bernoulli surfaces are convected by the tangentially mean inviscid flow field. The difference between the vane geometry of the uniform inlet flow and nonuniformmore » inlet flow diffusers is found to be most significant from 50 percent chord to the trailing edge region. The flows through both diffusers are computed by using Denton`s three-dimensional inviscid Euler solver and Dawes` three-dimensional Navier-Stokes solver under sheared in-flow conditions. The predictions indicate improved pressure recovery and internal flow field for the diffuser designed for shear inlet flow conditions.« less

Rough Electrode Creates Excess Capacitance in Thin-Film Capacitors

PubMed Central

2017-01-01

The parallel-plate capacitor equation is widely used in contemporary material research for nanoscale applications and nanoelectronics. To apply this equation, flat and smooth electrodes are assumed for a capacitor. This essential assumption is often violated for thin-film capacitors because the formation of nanoscale roughness at the electrode interface is very probable for thin films grown via common deposition methods. In this work, we experimentally and theoretically show that the electrical capacitance of thin-film capacitors with realistic interface roughness is significantly larger than the value predicted by the parallel-plate capacitor equation. The degree of the deviation depends on the strength of the roughness, which is described by three roughness parameters for a self-affine fractal surface. By applying an extended parallel-plate capacitor equation that includes the roughness parameters of the electrode, we are able to calculate the excess capacitance of the electrode with weak roughness. Moreover, we introduce the roughness parameter limits for which the simple parallel-plate capacitor equation is sufficiently accurate for capacitors with one rough electrode. Our results imply that the interface roughness beyond the proposed limits cannot be dismissed unless the independence of the capacitance from the interface roughness is experimentally demonstrated. The practical protocols suggested in our work for the reliable use of the parallel-plate capacitor equation can be applied as general guidelines in various fields of interest. PMID:28745040

Rough Electrode Creates Excess Capacitance in Thin-Film Capacitors.

PubMed

Torabi, Solmaz; Cherry, Megan; Duijnstee, Elisabeth A; Le Corre, Vincent M; Qiu, Li; Hummelen, Jan C; Palasantzas, George; Koster, L Jan Anton

2017-08-16

The parallel-plate capacitor equation is widely used in contemporary material research for nanoscale applications and nanoelectronics. To apply this equation, flat and smooth electrodes are assumed for a capacitor. This essential assumption is often violated for thin-film capacitors because the formation of nanoscale roughness at the electrode interface is very probable for thin films grown via common deposition methods. In this work, we experimentally and theoretically show that the electrical capacitance of thin-film capacitors with realistic interface roughness is significantly larger than the value predicted by the parallel-plate capacitor equation. The degree of the deviation depends on the strength of the roughness, which is described by three roughness parameters for a self-affine fractal surface. By applying an extended parallel-plate capacitor equation that includes the roughness parameters of the electrode, we are able to calculate the excess capacitance of the electrode with weak roughness. Moreover, we introduce the roughness parameter limits for which the simple parallel-plate capacitor equation is sufficiently accurate for capacitors with one rough electrode. Our results imply that the interface roughness beyond the proposed limits cannot be dismissed unless the independence of the capacitance from the interface roughness is experimentally demonstrated. The practical protocols suggested in our work for the reliable use of the parallel-plate capacitor equation can be applied as general guidelines in various fields of interest.

Development of a Reduced-Order Three-Dimensional Flow Model for Thermal Mixing and Stratification Simulation during Reactor Transients

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 developedmore » 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.« less

A high frequency analysis of electromagnetic plane wave scattering by perfectly-conducting semi-infinite parallel plate and rectangular waveguides with absorber coated inner walls

NASA Technical Reports Server (NTRS)

Noh, H. M.; Pathak, P. H.

1986-01-01

An approximate but sufficiently accurate high frequency solution which combines the uniform geometrical theory of diffraction (UTD) and the aperture integration (AI) method is developed for analyzing the problem of electromagnetic (EM) plane wave scattering by an open-ended, perfectly-conducting, semi-infinite hollow rectangular waveguide (or duct) with a thin, uniform layer of lossy or absorbing material on its inner wall, and with a planar termination inside. In addition, a high frequency solution for the EM scattering by a two dimensional (2-D), semi-infinite parallel plate waveguide with a absorber coating on the inner walls is also developed as a first step before analyzing the open-ended semi-infinite three dimensional (3-D) rectangular waveguide geometry. The total field scattered by the semi-infinite waveguide consists firstly of the fields scattered from the edges of the aperture at the open-end, and secondly of the fields which are coupled into the waveguide from the open-end and then reflected back from the interior termination to radiate out of the open-end. The first contribution to the scattered field can be found directly via the UTD ray method. The second contribution is found via the AI method which employs rays to describe the fields in the aperture that arrive there after reflecting from the interior termination. It is assumed that the direction of the incident plane wave and the direction of observation lie well inside the forward half space tht exists outside the half space containing the semi-infinite waveguide geometry. Also, the medium exterior to the waveguide is assumed to be free space.

Corrugated megathrust revealed offshore from Costa Rica

NASA Astrophysics Data System (ADS)

Edwards, Joel H.; Kluesner, Jared W.; Silver, Eli A.; Brodsky, Emily E.; Brothers, Daniel S.; Bangs, Nathan L.; Kirkpatrick, James D.; Wood, Ruby; Okamoto, Kristina

2018-03-01

Exhumed faults are rough, often exhibiting topographic corrugations oriented in the direction of slip; such features are fundamental to mechanical processes that drive earthquakes and fault evolution. However, our understanding of corrugation genesis remains limited due to a lack of in situ observations at depth, especially at subducting plate boundaries. Here we present three-dimensional seismic reflection data of the Costa Rica subduction zone that image a shallow megathrust fault characterized by corrugated, and chaotic and weakly corrugated topographies. The corrugated surfaces extend from near the trench to several kilometres down-dip, exhibit high reflection amplitudes (consistent with high fluid content/pressure) and trend 11-18° oblique to subduction, suggesting 15 to 25 mm yr-1 of trench-parallel slip partitioning across the plate boundary. The corrugations form along portions of the megathrust with greater cumulative slip and may act as fluid conduits. In contrast, weakly corrugated areas occur adjacent to active plate bending faults where the megathrust has migrated up-section, forming a nascent fault surface. The variations in megathrust roughness imaged here suggest that abandonment and then reestablishment of the megathrust up-section transiently increases fault roughness. Analogous corrugations may exist along significant portions of subduction megathrusts globally.

Corrugated megathrust revealed offshore from Costa Rica

USGS Publications Warehouse

Edwards, Joel H.; Kluesner, Jared; Silver, Eli A.; Brodsky, Emily E.; Brothers, Daniel; Bangs, Nathan L.; Kirkpatrick, James D.; Wood, Ruby; Okamato, Kristina

2018-01-01

Exhumed faults are rough, often exhibiting topographic corrugations oriented in the direction of slip; such features are fundamental to mechanical processes that drive earthquakes and fault evolution. However, our understanding of corrugation genesis remains limited due to a lack of in situ observations at depth, especially at subducting plate boundaries. Here we present three-dimensional seismic reflection data of the Costa Rica subduction zone that image a shallow megathrust fault characterized by corrugated, and chaotic and weakly corrugated topographies. The corrugated surfaces extend from near the trench to several kilometres down-dip, exhibit high reflection amplitudes (consistent with high fluid content/pressure) and trend 11–18° oblique to subduction, suggesting 15 to 25 mm yr−1 of trench-parallel slip partitioning across the plate boundary. The corrugations form along portions of the megathrust with greater cumulative slip and may act as fluid conduits. In contrast, weakly corrugated areas occur adjacent to active plate bending faults where the megathrust has migrated up-section, forming a nascent fault surface. The variations in megathrust roughness imaged here suggest that abandonment and then reestablishment of the megathrust up-section transiently increases fault roughness. Analogous corrugations may exist along significant portions of subduction megathrusts globally.

Directly measuring of thermal pulse transfer in one-dimensional highly aligned carbon nanotubes

PubMed Central

Zhang, Guang; Liu, Changhong; Fan, Shoushan

2013-01-01

Using a simple and precise instrument system, we directly measured the thermo-physical properties of one-dimensional highly aligned carbon nanotubes (CNTs). A kind of CNT-based macroscopic materials named super aligned carbon nanotube (SACNT) buckypapers was measured in our experiment. We defined a new one-dimensional parameter, the “thermal transfer speed” to characterize the thermal damping mechanisms in the SACNT buckypapers. Our results indicated that the SACNT buckypapers with different densities have obviously different thermal transfer speeds. Furthermore, we found that the thermal transfer speed of high-density SACNT buckypapers may have an obvious damping factor along the CNTs aligned direction. The anisotropic thermal diffusivities of SACNT buckypapers could be calculated by the thermal transfer speeds. The thermal diffusivities obviously increase as the buckypaper-density increases. For parallel SACNT buckypapers, the thermal diffusivity could be as high as 562.2 ± 55.4 mm2/s. The thermal conductivities of these SACNT buckypapers were also calculated by the equation k = Cpαρ. PMID:23989589

Directly measuring of thermal pulse transfer in one-dimensional highly aligned carbon nanotubes.

PubMed

Zhang, Guang; Liu, Changhong; Fan, Shoushan

2013-01-01

Using a simple and precise instrument system, we directly measured the thermo-physical properties of one-dimensional highly aligned carbon nanotubes (CNTs). A kind of CNT-based macroscopic materials named super aligned carbon nanotube (SACNT) buckypapers was measured in our experiment. We defined a new one-dimensional parameter, the "thermal transfer speed" to characterize the thermal damping mechanisms in the SACNT buckypapers. Our results indicated that the SACNT buckypapers with different densities have obviously different thermal transfer speeds. Furthermore, we found that the thermal transfer speed of high-density SACNT buckypapers may have an obvious damping factor along the CNTs aligned direction. The anisotropic thermal diffusivities of SACNT buckypapers could be calculated by the thermal transfer speeds. The thermal diffusivities obviously increase as the buckypaper-density increases. For parallel SACNT buckypapers, the thermal diffusivity could be as high as 562.2 ± 55.4 mm(2)/s. The thermal conductivities of these SACNT buckypapers were also calculated by the equation k = Cpαρ.

Anomalous cation diffusion in salt-doped confined bilayer ice.

PubMed

Qiu, Hu; Xue, Minmin; Shen, Chun; Guo, Wanlin

2018-05-17

The diffusive dynamics of aqueous electrolyte solutions in nanoconfined spaces has attracted considerable attention due to their potential applications in desalination, biosensors and supercapacitors. Here we show by molecular dynamics simulations that lithium and sodium ions diffuse at a rate at least an order of magnitude higher than that of water molecules when the ions are trapped in an ice bilayer confined between two parallel plates. This novel picture is in sharp contrast to the prevailing view that the diffusion rate of ions is comparable to or even lower than that of water in both bulk and confined solutions. The predicted high ion mobility stems from frequent lateral hopping of ions along the coordination sites inside the hydrogen-bonding network connecting the two water layers of the ice bilayer. This anomalous diffusion should provide new insights into the physics of confined aqueous electrolytes.

Resonant Interaction of a Rectangular Jet with a Flat-Plate

NASA Technical Reports Server (NTRS)

Zaman, K. B. M. Q.; Fagan, A. F.; Clem, M. M.; Brown, C. A.

2014-01-01

A resonant interaction between a large aspect ratio rectangular jet and a flat-plate is addressed in this experimental study. The plate is placed parallel to but away from the direct path of the jet. At high subsonic conditions and for certain relative locations of the plate, the resonance accompanied by an audible tone is encountered. The trends of the tone frequency variation exhibit some similarities to, but also marked differences from, corresponding trends of the well-known edge-tone phenomenon. Under the resonant condition flow visualization indicates a periodic flapping motion of the jet column. Phase-averaged Mach number data obtained near the plate's trailing edge illustrate that the jet cross-section goes through large contortions within the period of the tone. Farther downstream a clear 'axis switching' takes place. These results suggest that the assumption of two-dimensionality should be viewed with caution in any analysis of the flow.

Ground cross-modal impedance as a tool for analyzing ground/plate interaction and ground wave propagation.

PubMed

Grau, L; Laulagnet, B

2015-05-01

An analytical approach is investigated to model ground-plate interaction based on modal decomposition and the two-dimensional Fourier transform. A finite rectangular plate subjected to flexural vibration is coupled with the ground and modeled with the Kirchhoff hypothesis. A Navier equation represents the stratified ground, assumed infinite in the x- and y-directions and free at the top surface. To obtain an analytical solution, modal decomposition is applied to the structure and a Fourier Transform is applied to the ground. The result is a new tool for analyzing ground-plate interaction to resolve this problem: ground cross-modal impedance. It allows quantifying the added-stiffness, added-mass, and added-damping from the ground to the structure. Similarity with the parallel acoustic problem is highlighted. A comparison between the theory and the experiment shows good matching. Finally, specific cases are investigated, notably the influence of layer depth on plate vibration.

Size and Charge Dependence of Ion Transport in Human Nail Plate

PubMed Central

Baswan, Sudhir M.; Li, S. Kevin; LaCount, Terri D.; Kasting, Gerald B.

2016-01-01

The electrical properties of human nail plate are poorly characterized, yet are a key determinate of the potential to treat nail diseases such as onychomycosis using iontophoresis. In order to address this deficiency, molar conductivities of 17 electrolytes comprising 12 ionic species were determined in hydrated human nail plate in vitro. Cation transport numbers across the nail for 11 of these electrolytes were determined by the electromotive force method. Effective ionic mobilities and diffusivities at infinite dilution for all ionic species were determined by regression analysis. The ratios of diffusivities in nail to those in solution were found to correlate inversely with the hydrodynamic radii of the ions according to a power law relationship having an exponent of −1.75 ± 0.27, a substantially steeper size dependence than observed for similar experiments in skin. Effective diffusivities of cations in nail were three-fold higher than those of comparably sized anions. These results reflect the strong size and charge selectivity of the nail plate for ionic conduction and diffusion. The analysis implies that efficient transungual iontophoretic delivery of ionized drugs having radii upwards of 5 Å (approximately MW ≥ 340 Da) will require chemical or mechanical alteration of the nail plate. PMID:26886342

Diffuse Pacific-North American plate boundary: 1000 km of dextral shear inferred from modeling geodetic data

USGS Publications Warehouse

Parsons, T.; Thatcher, W.

2011-01-01

Geodetic measurements tell us that the eastern part of the Basin and Range Province expands in an east-west direction relative to stable North America, whereas the western part of the province moves to the northwest. We develop three-dimensional finite element representations of the western United States lithosphere in an effort to understand the global positioning system (GPS) signal. The models are constrained by known bounding-block velocities and topography, and Basin and Range Province deformation is represented by simple plastic (thermal creep) rheology. We show that active Basin and Range spreading by gravity collapse is expected to have a strong southward component that does not match the GPS signal. We can reconcile the gravitational component of displacement with observed velocity vectors if the Pacific plate applies northwest-directed shear stress to the Basin and Range via the Sierra Nevada block. This effect reaches at least 1000 km east of the San Andreas fault in our models. ?? 2011 Geological Society of America.

Manganese molybdate nanoflakes on silicon microchannel plates as novel nano energetic material

PubMed Central

Zhang, Chi; Wu, Dajun; Shi, Liming; Zhu, Yiping; Xiong, Dayuan; Xu, Shaohui; Huang, Rong; Qi, Ruijuan; Zhang, Wenchao; Chu, Paul K.

2017-01-01

Nano energetic materials have attracted great attention recently owing to their potential applications for both civilian and military purposes. By introducing silicon microchannel plates (Si-MCPs) three-dimensional (3D)-ordered structures, monocrystalline MnMoO4 with a size of tens of micrometres and polycrystalline MnMoO4 nanoflakes are produced on the surface and sidewall of nickel-coated Si-MCP, respectively. The MnMoO4 crystals ripen controllably forming polycrystalline nanoflakes with lattice fringes of 0.542 nm corresponding to the (1¯11) plane on the sidewall. And these MnMoO4 nanoflakes show apparent thermite performance which is rarely reported and represents MnMoO4 becoming a new category of energetic materials after nanocrystallization. Additionally, the nanocrystallization mechanism is interpreted by ionic diffusion caused by 3D structure. The results indicate that the Si-MCP is a promising substrate for nanocrystallization of energetic materials such as MnMoO4. PMID:29308255

Manganese molybdate nanoflakes on silicon microchannel plates as novel nano energetic material.

PubMed

Zhang, Chi; Wu, Dajun; Shi, Liming; Zhu, Yiping; Xiong, Dayuan; Xu, Shaohui; Huang, Rong; Qi, Ruijuan; Zhang, Wenchao; Wang, Lianwei; Chu, Paul K

2017-12-01

Nano energetic materials have attracted great attention recently owing to their potential applications for both civilian and military purposes. By introducing silicon microchannel plates (Si-MCPs) three-dimensional (3D)-ordered structures, monocrystalline MnMoO 4 with a size of tens of micrometres and polycrystalline MnMoO 4 nanoflakes are produced on the surface and sidewall of nickel-coated Si-MCP, respectively. The MnMoO 4 crystals ripen controllably forming polycrystalline nanoflakes with lattice fringes of 0.542 nm corresponding to the [Formula: see text] plane on the sidewall. And these MnMoO 4 nanoflakes show apparent thermite performance which is rarely reported and represents MnMoO 4 becoming a new category of energetic materials after nanocrystallization. Additionally, the nanocrystallization mechanism is interpreted by ionic diffusion caused by 3D structure. The results indicate that the Si-MCP is a promising substrate for nanocrystallization of energetic materials such as MnMoO 4 .

Unsteady boundary-layer injection

NASA Technical Reports Server (NTRS)

Telionis, D. P.; Jones, G. S.

1981-01-01

The boundary-layer equations for two-dimensional incompressible flow are integrated numerically for the flow over a flat plate and a Howarth body. Injection is introduced either impulsively or periodically along a narrow strip. Results indicate that injection perpendicular to the wall is transmitted instantly across the boundary layer and has little effect on the velocity profile parallel to the wall. The effect is a little more noticeable for flows with adverse pressure gradients. Injection parallel to the wall results in fuller velocity profiles. Parallel and oscillatory injection appears to influence the mean. The amplitude of oscillation decreases with distance from the injection strip but further downstream it increases again in a manner reminiscent of an unstable process.

Three-dimensional solutions for the free vibrations and buckling of thermally stressed multilayered angle-ply composite plates

NASA Technical Reports Server (NTRS)

Noor, Ahmed K.; Burton, W. S.

1992-01-01

Analytic three-dimensional elasticity solutions are developed for the free vibration and buckling of thermally stressed rectangular multilayered angle-ply anisotropic plates which are assumed to have an antisymmetric lamination with respect to the middle plane. Sensitivity derivatives are evaluated and used to investigate the sensitivity of the vibration and buckling responses to variations in the different lamination and material parameters of the plate. A Duhamel-Neumann-type constitutive model is used, and the material properties are assumed to be independent of temperature. Numerical results are presented, showing the effects of variations in the material characteristics and fiber orientation of different layers, as well as the effect of initial thermal deformation on the vibrational and buckling responses of the plate.

[Three-dimensional Finite Element Analysis to T-shaped Fracture of Pelvis in Sitting Position].

PubMed

Fan, Yanping; Lei, Jianyin; Liu, Haibo; Li, Zhiqiang; Cai, Xianhua; Chen, Weiyi

2015-10-01

We developed a three-dimensional finite element model of the pelvis. According to Letournel methods, we established a pelvis model of T-shaped fracture with its three different fixation systems, i. e. double column reconstruction plates, anterior column plate combined with posterior column screws and anterior column plate combined with quadrilateral area screws. It was found that the pelvic model was effective and could be used to simulate the mechanical behavior of the pelvis. Three fixation systems had great therapeutic effect on the T-shaped fracture. All fixation systems could increase the stiffness of the model, decrease the stress concentration level and decrease the displacement difference along the fracture line. The quadrilateral area screws, which were drilled into cortical bone, could generate beneficial effect on the T-type fracture. Therefore, the third fixation system mentioned above (i. e. the anterior column plate combined with quadrilateral area screws) has the best biomechanical stability to the T-type fracture.

Three-dimensional magnetic bubble memory system

NASA Technical Reports Server (NTRS)

Stadler, Henry L. (Inventor); Katti, Romney R. (Inventor); Wu, Jiin-Chuan (Inventor)

1994-01-01

A compact memory uses magnetic bubble technology for providing data storage. A three-dimensional arrangement, in the form of stacks of magnetic bubble layers, is used to achieve high volumetric storage density. Output tracks are used within each layer to allow data to be accessed uniquely and unambiguously. Storage can be achieved using either current access or field access magnetic bubble technology. Optical sensing via the Faraday effect is used to detect data. Optical sensing facilitates the accessing of data from within the three-dimensional package and lends itself to parallel operation for supporting high data rates and vector and parallel processing.

The Malpelo Plate Hypothesis and Implications for Non-closure of the Cocos-Nazca-Pacific Plate Motion Circuit

NASA Astrophysics Data System (ADS)

Zhang, T.; Gordon, R. G.; Mishra, J. K.; Wang, C.

2017-12-01

The non-closure of the Cocos-Nazca-Pacific plate motion circuit by 15.0 mm a-1± 3.8 mm a-1 (95% confidence limits throughout this abstract) [DeMets et al. 2010] represents a daunting challenge to the central tenet of plate tectonics—that the plates are rigid. This misfit is difficult to explain from known processes of intraplate deformation, such as horizontal thermal contraction [Collette, 1974; Kumar and Gordon, 2009; Kreemer and Gordon, 2014; Mishra and Gordon, 2016] or movement of plates over a non-spherical Earth [McKenzie, 1972; Turcotte and Oxburgh, 1973]. Possibly there are one or more unrecognized plate boundaries in the circuit, but no such boundary has been found to date. To make progress on this problem, we present three new Cocos-Nazca transform fault azimuths from multibeam data now available through Geomapapp's global multi-resolution topography [Ryan et al., 2009]. We determine a new Cocos-Nazca best-fitting angular velocity from the three new transform-fault azimuths combined with the spreading rates of DeMets et al. [2010]. The new direction of relative plate motion is 3.3° ±1.8° clockwise of prior estimates and is 4.9° ±2.7° clockwise of the azimuth of the Panama transform fault, demonstrating that the Panama transform fault does not parallel Nazca-Cocos plate motion. We infer that the plate east of the Panama transform fault is not the Nazca plate, but instead is a microplate that we term the Malpelo plate. We hypothesize that a diffuse plate boundary separates the Malpelo plate from the much larger Nazca plate. The Malpelo plate extends only as far north as ≈6°N where seismicity marks another boundary with a previously recognized microplate, the Coiba plate [Pennington, 1981, Adamek et al., 1988]. The Malpelo plate moves 5.9 mm a-1 relative to the Nazca plate along the Panama transform fault. When we sum the Cocos-Pacific and Pacific-Nazca best-fitting angular velocities of DeMets et al. [2010] with our new Nazca-Cocos best-fitting angular velocity, we find a new linear velocity of non-closure of 11.6 mm a-1± 3.8 mm a-1, i.e., the non-closure is reduced by 3.4 mm a-1. The non-closure still seems too large to be due entirely to intraplate deformation and suggests that one or more additional plate boundaries remain to be discovered.

Two-dimensional dynamics of a trapped active Brownian particle in a shear flow

NASA Astrophysics Data System (ADS)

Li, Yunyun; Marchesoni, Fabio; Debnath, Tanwi; Ghosh, Pulak K.

2017-12-01

We model the two-dimensional dynamics of a pointlike artificial microswimmer diffusing in a harmonic trap subject to the shear flow of a highly viscous medium. The particle is driven simultaneously by the linear restoring force of the trap, the drag force exerted by the flow, and the torque due to the shear gradient. For a Couette flow, elliptical orbits in the noiseless regime, and the correlation functions between the particle's displacements parallel and orthogonal to the flow are computed analytically. The effects of thermal fluctuations (translational) and self-propulsion fluctuations (angular) are treated separately. Finally, we discuss how to extend our approach to the diffusion of a microswimmer in a Poiseuille flow. These results provide an accurate reference solution to investigate, both numerically and experimentally, hydrodynamics corrections to the diffusion of active matter in confined geometries.

Implementation and Characterization of Three-Dimensional Particle-in-Cell Codes on Multiple-Instruction-Multiple-Data Massively Parallel Supercomputers

NASA Technical Reports Server (NTRS)

Lyster, P. M.; Liewer, P. C.; Decyk, V. K.; Ferraro, R. D.

1995-01-01

A three-dimensional electrostatic particle-in-cell (PIC) plasma simulation code has been developed on coarse-grain distributed-memory massively parallel computers with message passing communications. Our implementation is the generalization to three-dimensions of the general concurrent particle-in-cell (GCPIC) algorithm. In the GCPIC algorithm, the particle computation is divided among the processors using a domain decomposition of the simulation domain. In a three-dimensional simulation, the domain can be partitioned into one-, two-, or three-dimensional subdomains ("slabs," "rods," or "cubes") and we investigate the efficiency of the parallel implementation of the push for all three choices. The present implementation runs on the Intel Touchstone Delta machine at Caltech; a multiple-instruction-multiple-data (MIMD) parallel computer with 512 nodes. We find that the parallel efficiency of the push is very high, with the ratio of communication to computation time in the range 0.3%-10.0%. The highest efficiency (> 99%) occurs for a large, scaled problem with 64(sup 3) particles per processing node (approximately 134 million particles of 512 nodes) which has a push time of about 250 ns per particle per time step. We have also developed expressions for the timing of the code which are a function of both code parameters (number of grid points, particles, etc.) and machine-dependent parameters (effective FLOP rate, and the effective interprocessor bandwidths for the communication of particles and grid points). These expressions can be used to estimate the performance of scaled problems--including those with inhomogeneous plasmas--to other parallel machines once the machine-dependent parameters are known.

A parallel finite-difference method for computational aerodynamics

NASA Technical Reports Server (NTRS)

Swisshelm, Julie M.

1989-01-01

A finite-difference scheme for solving complex three-dimensional aerodynamic flow on parallel-processing supercomputers is presented. The method consists of a basic flow solver with multigrid convergence acceleration, embedded grid refinements, and a zonal equation scheme. Multitasking and vectorization have been incorporated into the algorithm. Results obtained include multiprocessed flow simulations from the Cray X-MP and Cray-2. Speedups as high as 3.3 for the two-dimensional case and 3.5 for segments of the three-dimensional case have been achieved on the Cray-2. The entire solver attained a factor of 2.7 improvement over its unitasked version on the Cray-2. The performance of the parallel algorithm on each machine is analyzed.

Parallel Plate System for Collecting Data Used to Determine Viscosity

NASA Technical Reports Server (NTRS)

Ethridge, Edwin C. (Inventor); Kaukler, William (Inventor)

2013-01-01

A parallel-plate system collects data used to determine viscosity. A first plate is coupled to a translator so that the first plate can be moved along a first direction. A second plate has a pendulum device coupled thereto such that the second plate is suspended above and parallel to the first plate. The pendulum device constrains movement of the second plate to a second direction that is aligned with the first direction and is substantially parallel thereto. A force measuring device is coupled to the second plate for measuring force along the second direction caused by movement of the second plate.

A new procedure for investigating three-dimensional stress fields in a thin plate with a through-the-thickness crack

NASA Astrophysics Data System (ADS)

Yi, Dake; Wang, TzuChiang

2018-06-01

In the paper, a new procedure is proposed to investigate three-dimensional fracture problems of a thin elastic plate with a long through-the-thickness crack under remote uniform tensile loading. The new procedure includes a new analytical method and high accurate finite element simulations. In the part of theoretical analysis, three-dimensional Maxwell stress functions are employed in order to derive three-dimensional crack tip fields. Based on the theoretical analysis, an equation which can describe the relationship among the three-dimensional J-integral J( z), the stress intensity factor K( z) and the tri-axial stress constraint level T z ( z) is derived first. In the part of finite element simulations, a fine mesh including 153360 elements is constructed to compute the stress field near the crack front, J( z) and T z ( z). Numerical results show that in the plane very close to the free surface, the K field solution is still valid for in-plane stresses. Comparison with the numerical results shows that the analytical results are valid.

Implementation of a 3D mixing layer code on parallel computers

NASA Technical Reports Server (NTRS)

Roe, K.; Thakur, R.; Dang, T.; Bogucz, E.

1995-01-01

This paper summarizes our progress and experience in the development of a Computational-Fluid-Dynamics code on parallel computers to simulate three-dimensional spatially-developing mixing layers. In this initial study, the three-dimensional time-dependent Euler equations are solved using a finite-volume explicit time-marching algorithm. The code was first programmed in Fortran 77 for sequential computers. The code was then converted for use on parallel computers using the conventional message-passing technique, while we have not been able to compile the code with the present version of HPF compilers.

Three-dimensional scapular dyskinesis in hook-plated acromioclavicular dislocation including hook motion.

PubMed

Kim, Eugene; Lee, Seunghee; Jeong, Hwa-Jae; Park, Jai Hyung; Park, Se-Jin; Lee, Jaewook; Kim, Woosub; Park, Hee Jin; Lee, So Yeon; Murase, Tsuyoshi; Sugamoto, Kazuomi; Ikemoto, Sumika

2018-06-01

The purpose of this study is to analyze the 3-dimensional scapular dyskinesis and the kinematics of a hook plate relative to the acromion after hook-plated acromioclavicular dislocation in vivo. Reported complications of acromioclavicular reduction using a hook plate include subacromial erosion and impingement. However, there are few reports of the 3-dimensional kinematics of the hook and scapula after the aforementioned surgical procedure. We studied 15 cases of acromioclavicular dislocation treated with a hook plate and 15 contralateral normal shoulders using computed tomography in the neutral and full forward flexion positions. Three-dimensional motion of the scapula relative to the thorax during arm elevation was analyzed using a computer simulation program. We also measured the distance from the tip of the hook plate to the greater tuberosity, as well as the angular motion of the plate tip in the subacromial space. Decreased posterior tilting (22° ± 10° vs 31° ± 8°) in the sagittal plane and increased external rotation (19° ± 9° vs 7° ± 5°) in the axial plane were evident in the affected shoulders. The mean values of translation of the hook plate and angular motion against the acromion were 4.0 ± 1.6 mm and 15° ± 8°, respectively. The minimum value of the distance from the hook plate to the humeral head tuberosity was 6.9 mm during arm elevation. Acromioclavicular reduction using a hook plate may cause scapular dyskinesis. Translational and angular motion of the hook plate against the acromion could lead to subacromial erosion. However, the hook does not seem to impinge directly on the humeral head. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Effects of curved midline and varying width on the description of the effective diffusivity of Brownian particles

NASA Astrophysics Data System (ADS)

Chávez, Yoshua; Chacón-Acosta, Guillermo; Dagdug, Leonardo

2018-05-01

Axial diffusion in channels and tubes of smoothly-varying geometry can be approximately described as one-dimensional diffusion in the entropy potential with a position-dependent effective diffusion coefficient, by means of the modified Fick–Jacobs equation. In this work, we derive analytical expressions for the position-dependent effective diffusivity for two-dimensional asymmetric varying-width channels, and for three-dimensional curved midline tubes, formed by straight walls. To this end, we use a recently developed theoretical framework using the Frenet–Serret moving frame as the coordinate system (2016 J. Chem. Phys. 145 074105). For narrow tubes and channels, an effective one-dimensional description reducing the diffusion equation to a Fick–Jacobs-like equation in general coordinates is used. From this last equation, one can calculate the effective diffusion coefficient applying Neumann boundary conditions.

Three-dimensional inversion of regional P and S arrival times in the East Aleutians and sources of subduction zone gravity highs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abers, G.A.

1994-03-10

Free-air gravity highs over forearcs represent a large fraction of the power in the Earth`s anomalous field, yet their origin remains uncertain. Seismic velocities, as indicators of density, are estimated here as a means to compare the relative importance of upper plate sources for the gravity high with sources in the downgoing plate. P and S arrival times for local earthquakes, recorded by a seismic network in the eastern Aleutians, are inverted for three-dimensional velocity structure between the volcanic arc and the downgoing plate. A three-dimensional ray tracing scheme is used to invert the 7974 P and 6764 S arrivalsmore » for seismic velocities and hypocenters of 635 events. One-dimensional inversions show that station P residuals are systematically 0.25 - 0.5 s positive at stations 0-30 km north of the Aleutian volcanic arc, indicating slow material, while residuals at stations 10-30 km south of the arc are 0.1-0.25 s negative. Both features are explained in three-dimensional inversions by velocity variations at depths less than 25-35 km. Tests using a one-dimensional or a two-dimensional slab starting model show that below 100 km depth, velocities are poorly determined and trade off almost completely with hypocenters for earthquakes at these depths. The locations of forearc velocity highs, in the crust of the upper plate, correspond to the location of the gravity high between the trench and volcanic arc. Free-air anomalies, calculated from the three-dimensional velocity inversion result, match observed gravity for a linear density-velocity relationship between 0.1 and 0.3 (Mg m{sup {minus}3})/(km s{sup {minus}1}), when a 50-km-thick slab is included with a density of 0.055{+-}0.005 Mg m{sup {minus}3}. Values outside these ranges do not match the observed gravity. The slab alone contributes one third to one half of the total 75-150 mGal amplitude of the gravity high but predicts a high that is much broader than is observed.« less

Hierarchic models for laminated plates

NASA Technical Reports Server (NTRS)

Szabo, Barna A.; Actis, Ricardo L.

1991-01-01

The research conducted in the formulation of hierarchic models for laminated plates is described. The work is an extension of the work done for laminated strips. The use of a single parameter, beta, is investigated that represents the degree to which the equilibrium equations of three dimensional elasticity are satisfied. The powers of beta identify members in the hierarchic sequence. Numerical examples that were analyzed with the proposed sequence of models are included. The results obtained for square plates with uniform loading and homogeneous boundary conditions are very encouraging. Several cross-ply and angle-ply laminates were evaluated and the results compared with those of the fully three dimensional model, computed using MSC/PROBE, and with previously reported work on laminated strips.

Hierarchic plate and shell models based on p-extension

NASA Technical Reports Server (NTRS)

Szabo, Barna A.; Sahrmann, Glenn J.

1988-01-01

Formulations of finite element models for beams, arches, plates and shells based on the principle of virtual work was studied. The focus is on computer implementation of hierarchic sequences of finite element models suitable for numerical solution of a large variety of practical problems which may concurrently contain thin and thick plates and shells, stiffeners, and regions where three dimensional representation is required. The approximate solutions corresponding to the hierarchic sequence of models converge to the exact solution of the fully three dimensional model. The stopping criterion is based on: (1) estimation of the relative error in energy norm; (2) equilibrium tests, and (3) observation of the convergence of quantities of interest.

An analytical theory for a three-dimensional thick-disc thin-plate vibratory gyroscope

NASA Astrophysics Data System (ADS)

Sedebo, G. T.; Joubert, S. V.; Shatalov, M. Y.

2018-04-01

We consider a cylindrical vibratory gyroscope comprising a not necessarliy thin-shelled annular disc with small-plate thickness, vibrating in the m -th vibration mode in-plane and in the (m + 1)st vibration mode out-of-plane. We derive the equations of motion for this contrivance in the “force-to-rebalance regime” and show how a slow (three-dimensional) inertial rotation rate of the gyroscope can be calculated in terms of amplitudes of vibration and other constants, all of which can be measured experimentally or calculated when the eigenfunctions and eigenvalues of the system are known. By means of a concrete example, a numerical experiment demonstrates how varying the inner radius of the annulus as well as the thickness of the plate allows us to “tune” the vibration frequencies of the in-plane and out-of-plane vibrations so that they coincide (for all practical purposes), eliminating any frequency split. Conventionally, an array of at least three thin-shelled hemispherical (or thin-ring) vibratory (resonator) gyroscopes is used to measure any three-dimensional rotation of the craft to which the gyroscopes are fixed. With the design proposed here, the array can be reduced to a solitary, tuned, annular thick-disc thin-plate vibratory gyroscope, reducing both size and cost.

Moment tensor inversion of the 2016 southeast offshore Mie earthquake in the Tonankai region using a three-dimensional velocity structure model: effects of the accretionary prism and subducting oceanic plate

NASA Astrophysics Data System (ADS)

Takemura, Shunsuke; Kimura, Takeshi; Saito, Tatsuhiko; Kubo, Hisahiko; Shiomi, Katsuhiko

2018-03-01

The southeast offshore Mie earthquake occurred on April 1, 2016 near the rupture area of the 1944 Tonankai earthquake, where seismicity around the interface of the Philippine Sea plate had been very low until this earthquake. Since this earthquake occurred outside of seismic arrays, the focal mechanism and depth were not precisely constrained using a one-dimensional velocity model, as in a conventional approach. We conducted a moment tensor inversion of this earthquake by using a three-dimensional velocity structure model. Before the analysis of observed data, we investigated the effects of offshore heterogeneous structures such as the seawater, accretionary prism, and subducting oceanic plate by using synthetic seismograms in a full three-dimensional model and simpler models. The accretionary prism and subducting oceanic plate play important roles in the moment tensor inversion for offshore earthquakes in the subduction zone. Particularly, the accretionary prism, which controls the excitation and propagation of long-period surface waves around the offshore region, provides better estimations of the centroid depths and focal mechanisms of earthquakes around the Nankai subduction zone. The result of moment tensor inversion for the 2016 southeast offshore Mie earthquake revealed low-angle thrust faulting with a moment magnitude of 5.6. According to geophysical surveys in the Nankai Trough, our results suggest that the rupture of this earthquake occurred on the interface of the Philippine Sea plate, rather than on a mega-splay fault. Detailed comparisons of first-motion polarizations provided additional constraints of the rupture that occurred on the interface of the Philippine Sea plate.

Effect of Shear Deformation and Continuity on Delamination Modelling with Plate Elements

NASA Technical Reports Server (NTRS)

Glaessgen, E. H.; Riddell, W. T.; Raju, I. S.

1998-01-01

The effects of several critical assumptions and parameters on the computation of strain energy release rates for delamination and debond configurations modeled with plate elements have been quantified. The method of calculation is based on the virtual crack closure technique (VCCT), and models that model the upper and lower surface of the delamination or debond with two-dimensional (2D) plate elements rather than three-dimensional (3D) solid elements. The major advantages of the plate element modeling technique are a smaller model size and simpler geometric modeling. Specific issues that are discussed include: constraint of translational degrees of freedom, rotational degrees of freedom or both in the neighborhood of the crack tip; element order and assumed shear deformation; and continuity of material properties and section stiffness in the vicinity of the debond front, Where appropriate, the plate element analyses are compared with corresponding two-dimensional plane strain analyses.

Effects of boundary layer refraction and fuselage scattering on fuselage surface noise from advanced turboprop propellers

NASA Technical Reports Server (NTRS)

Mcaninch, G. L.; Rawls, J. W., Jr.

1984-01-01

An acoustic disturbance's propagation through a boundary layer is discussed with a view to the analysis of the acoustic field generated by a propfan rotor incident to the fuselage of an aircraft. Applying the parallel flow assumption, the resulting partial differential equations are reduced to an ordinary acoustic pressure differential equation by means of the Fourier transform. The methods used for the solution of this equation include those of Frobenius and of analytic continuation; both yield exact solutions in series form. Two models of the aircraft fuselage-boundary layer system are considered, in the first of which the fuselage is replaced by a flat plate and the acoustic field is assumed to be two-dimensional, while in the second the fuselage is a cylinder in a fully three-dimensional acoustic field. It is shown that the boundary layer correction improves theory-data comparisons over simple application of a pressure-doubling rule at the fuselage.

Diffuse optical correlation tomography of cerebral blood flow during cortical spreading depression in rat brain

NASA Astrophysics Data System (ADS)

Zhou, Chao; Yu, Guoqiang; Furuya, Daisuke; Greenberg, Joel; Yodh, Arjun; Durduran, Turgut

2006-02-01

Diffuse optical correlation methods were adapted for three-dimensional (3D) tomography of cerebral blood flow (CBF) in small animal models. The image reconstruction was optimized using a noise model for diffuse correlation tomography which enabled better data selection and regularization. The tomographic approach was demonstrated with simulated data and during in-vivo cortical spreading depression (CSD) in rat brain. Three-dimensional images of CBF were obtained through intact skull in tissues(~4mm) deep below the cortex.

Three-dimensional models of deformation near strike-slip faults

USGS Publications Warehouse

ten Brink, Uri S.; Katzman, Rafael; Lin, J.

1996-01-01

We use three-dimensional elastic models to help guide the kinematic interpretation of crustal deformation associated with strike-slip faults. Deformation of the brittle upper crust in the vicinity of strike-slip fault systems is modeled with the assumption that upper crustal deformation is driven by the relative plate motion in the upper mantle. The driving motion is represented by displacement that is specified on the bottom of a 15-km-thick elastic upper crust everywhere except in a zone of finite width in the vicinity of the faults, which we term the "shear zone." Stress-free basal boundary conditions are specified within the shear zone. The basal driving displacement is either pure strike slip or strike slip with a small oblique component, and the geometry of the fault system includes a single fault, several parallel faults, and overlapping en echelon faults. We examine the variations in deformation due to changes in the width of the shear zone and due to changes in the shear strength of the faults. In models with weak faults the width of the shear zone has a considerable effect on the surficial extent and amplitude of the vertical and horizontal deformation and on the amount of rotation around horizontal and vertical axes. Strong fault models have more localized deformation at the tip of the faults, and the deformation is partly distributed outside the fault zone. The dimensions of large basins along strike-slip faults, such as the Rukwa and Dead Sea basins, and the absence of uplift around pull-apart basins fit models with weak faults better than models with strong faults. Our models also suggest that the length-to-width ratio of pull-apart basins depends on the width of the shear zone and the shear strength of the faults and is not constant as previously suggested. We show that pure strike-slip motion can produce tectonic features, such as elongate half grabens along a single fault, rotated blocks at the ends of parallel faults, or extension perpendicular to overlapping en echelon faults, which can be misinterpreted to indicate a regional component of extension. Zones of subsidence or uplift can become wider than expected for transform plate boundaries when a minor component of oblique motion is added to a system of parallel strike-slip faults.

Three-dimensional models of deformation near strike-slip faults

USGS Publications Warehouse

ten Brink, Uri S.; Katzman, Rafael; Lin, Jian

1996-01-01

We use three-dimensional elastic models to help guide the kinematic interpretation of crustal deformation associated with strike-slip faults. Deformation of the brittle upper crust in the vicinity of strike-slip fault systems is modeled with the assumption that upper crustal deformation is driven by the relative plate motion in the upper mantle. The driving motion is represented by displacement that is specified on the bottom of a 15-km-thick elastic upper crust everywhere except in a zone of finite width in the vicinity of the faults, which we term the “shear zone.” Stress-free basal boundary conditions are specified within the shear zone. The basal driving displacement is either pure strike slip or strike slip with a small oblique component, and the geometry of the fault system includes a single fault, several parallel faults, and overlapping en echelon faults. We examine the variations in deformation due to changes in the width of the shear zone and due to changes in the shear strength of the faults. In models with weak faults the width of the shear zone has a considerable effect on the surficial extent and amplitude of the vertical and horizontal deformation and on the amount of rotation around horizontal and vertical axes. Strong fault models have more localized deformation at the tip of the faults, and the deformation is partly distributed outside the fault zone. The dimensions of large basins along strike-slip faults, such as the Rukwa and Dead Sea basins, and the absence of uplift around pull-apart basins fit models with weak faults better than models with strong faults. Our models also suggest that the length-to-width ratio of pull-apart basins depends on the width of the shear zone and the shear strength of the faults and is not constant as previously suggested. We show that pure strike-slip motion can produce tectonic features, such as elongate half grabens along a single fault, rotated blocks at the ends of parallel faults, or extension perpendicular to overlapping en echelon faults, which can be misinterpreted to indicate a regional component of extension. Zones of subsidence or uplift can become wider than expected for transform plate boundaries when a minor component of oblique motion is added to a system of parallel strike-slip faults.

Nonlinear theory for laminated and thick plates and shells including the effects of transverse shearing

NASA Technical Reports Server (NTRS)

Stein, M.

1985-01-01

Nonlinear strain displacement relations for three-dimensional elasticity are determined in orthogonal curvilinear coordinates. To develop a two-dimensional theory, the displacements are expressed by trigonometric series representation through-the-thickness. The nonlinear strain-displacement relations are expanded into series which contain all first and second degree terms. In the series for the displacements only the first few terms are retained. Insertion of the expansions into the three-dimensional virtual work expression leads to nonlinear equations of equilibrium for laminated and thick plates and shells that include the effects of transverse shearing. Equations of equilibrium and buckling equations are derived for flat plates and cylindrical shells. The shell equations reduce to conventional transverse shearing shell equations when the effects of the trigonometric terms are omitted and to classical shell equations when the trigonometric terms are omitted and the shell is assumed to be thin.

Three-dimensional characterization of bacterial microcolonies on solid agar-based culture media.

PubMed

Drazek, Laurent; Tournoud, Maud; Derepas, Frédéric; Guicherd, Maryse; Mahé, Pierre; Pinston, Frédéric; Veyrieras, Jean-Baptiste; Chatellier, Sonia

2015-02-01

For the last century, in vitro diagnostic process in microbiology has mainly relied on the growth of bacteria on the surface of a solid agar medium. Nevertheless, few studies focused in the past on the dynamics of microcolonies growth on agar surface before 8 to 10h of incubation. In this article, chromatic confocal microscopy has been applied to characterize the early development of a bacterial colony. This technology relies on a differential focusing depth of the white light. It allows one to fully measure the tridimensional shape of microcolonies more quickly than classical confocal microscopy but with the same spatial resolution. Placing the device in an incubator, the method was able to individually track colonies growing on an agar plate, and to follow the evolution of their surface or volume. Using an appropriate statistical modeling framework, for a given microorganism, the doubling time has been estimated for each individual colony, as well as its variability between colonies, both within and between agar plates. A proof of concept led on four bacterial strains of four distinct species demonstrated the feasibility and the interest of the approach. It showed in particular that doubling times derived from early tri-dimensional measurements on microcolonies differed from classical measurements in micro-dilutions based on optical diffusion. Such a precise characterization of the tri-dimensional shape of microcolonies in their late-lag to early-exponential phase could be beneficial in terms of in vitro diagnostics. Indeed, real-time monitoring of the biomass available in a colony could allow to run well established microbial identification workflows like, for instance, MALDI-TOF mass-spectrometry, as soon as a sufficient quantity of material is available, thereby reducing the time needed to provide a diagnostic. Moreover, as done for pre-identification of macro-colonies, morphological indicators such as three-dimensional growth profiles derived from microcolonies could be used to perform a first pre-identification step, but in a shorten time. Copyright © 2014 Elsevier B.V. All rights reserved.

Biomechanical evaluation of two types of short-stemmed hip prostheses compared to the trust plate prosthesis by three-dimensional measurement of micromotions.

PubMed

Fottner, Andreas; Schmid, Markus; Birkenmaier, Christof; Mazoochian, Farhad; Plitz, Wolfgang; Volkmar, Jansson

2009-06-01

Stemless and short-stemmed hip prostheses have been developed to preserve femoral bone stock. While all these prostheses claim a more or less physiological load transfer, clinical long-term results are only available for the stemless thrust plate prosthesis. In this study, the in vitro primary stability of the thrust plate prosthesis was compared to two types of short-stemmed prostheses. In addition to the well-established Mayo prosthesis, the modular Metha prosthesis was tested using cone adapters with 130 degrees and 140 degrees neck-shaft-angles. The prostheses were implanted in composite femurs and loaded dynamically (300-1700 N). Three-dimensional micromotions at the bone-prosthesis interface were measured. In addition, the three-dimensional deformations at the surface of the composite femur were measured to gain data on the strain distribution. For all tested prostheses, the micromotions did not exceed 150 microm, the critical value for osteointegration. The thrust plate prosthesis revealed similar motions as the short-stemmed prostheses. The short-stemmed prosthesis with the 130 degrees cone tended to have the highest micromotions of all tested short-stemmed prostheses. The thrust plate prosthesis revealed the lowest alteration of bone surface deformation after implantation. The comparably low micromotions of the thrust plate prosthesis and the short-stemmed prostheses should be conducive to osseous integration. The higher alteration of load transmission after implantation reveals a higher risk of stress shielding for the short-stemmed prostheses.

Quantum field between moving mirrors: A three dimensional example

NASA Technical Reports Server (NTRS)

Hacyan, S.; Jauregui, Roco; Villarreal, Carlos

1995-01-01

The scalar quantum field uniformly moving plates in three dimensional space is studied. Field equations for Dirichlet boundary conditions are solved exactly. Comparison of the resulting wavefunctions with their instantaneous static counterpart is performed via Bogolubov coefficients. Unlike the one dimensional problem, 'particle' creation as well as squeezing may occur. The time dependent Casimir energy is also evaluated.

Rapid Prediction of Unsteady Three-Dimensional Viscous Flows in Turbopump Geometries

NASA Technical Reports Server (NTRS)

Dorney, Daniel J.

1998-01-01

A program is underway to improve the efficiency of a three-dimensional Navier-Stokes code and generalize it for nozzle and turbopump geometries. Code modifications have included the implementation of parallel processing software, incorporation of new physical models and generalization of the multiblock capability. The final report contains details of code modifications, numerical results for several nozzle and turbopump geometries, and the implementation of the parallelization software.

Shallow cells in directional solidification

NASA Technical Reports Server (NTRS)

Merchant, G. J.; Davis, S. H.

1989-01-01

The existing theory on two-dimensional transitions (appropriate to thin parallel-plate geometries) is presented in such a way that it is possible to identify easily conditions for the onset of shallow cells. Conditions are given under which succinonitrile-acetone mixtures should undergo supercritical bifurcation in experimentally accessible ranges. These results suggest a means for the quantitative test of the Mullins and Sekerka (1964) model and its weakly nonlinear extensions.

UFO: A THREE-DIMENSIONAL NEUTRON DIFFUSION CODE FOR THE IBM 704

DOE Office of Scientific and Technical Information (OSTI.GOV)

Auerbach, E.H.; Jewett, J.P.; Ketchum, M.A.

A description of UFO, a code for the solution of the fewgroup neutron diffusion equation in three-dimensional Cartesian coordinates on the IBM 704, is given. An accelerated Liebmann flux iteration scheme is used, and optimum parameters can be calculated by the code whenever they are required. The theory and operation of the program are discussed. (auth)

Vibro-acoustic modeling and analysis of a coupled acoustic system comprising a partially opened cavity coupled with a flexible plate

NASA Astrophysics Data System (ADS)

Shi, Shuangxia; Su, Zhu; Jin, Guoyong; Liu, Zhigang

2018-01-01

This paper is concerned with the modeling and solution method of a three-dimensional (3D) coupled acoustic system comprising a partially opened cavity coupled with a flexible plate and an exterior field of semi-infinite size, which is ubiquitously encountered in architectural acoustics and is a reasonable representation of many engineering occasions. A general solution method is presented to predict the dynamic behaviors of the three-dimensional (3D) acoustic coupled system, in which the displacement of the plate and the sound pressure in the cavity are respectively constructed in the form of the two-dimensional and three-dimensional modified Fourier series with several auxiliary functions introduced to ensure the uniform convergence of the solution over the entire solution domain. The effect of the opening is taken into account via the work done by the sound pressure acting at the coupling aperture that is contributed from the vibration of particles on the acoustic coupling interface and on the structural-acoustic coupling interface. Both the acoustic coupling between finite cavity and exterior field and the structural-acoustic coupling between flexible plate and interior acoustic field are considered in the vibro-acoustic modeling of the three-dimensional acoustic coupled acoustic system. The dynamic responses of the coupled structural-acoustic system are obtained using the Rayleigh-Ritz procedure based on the energy expressions for the coupled system. The accuracy and effectiveness of the proposed method are validated through numerical examples and comparison with results obtained by the boundary element analysis. Furthermore, the influence of the opening and the cavity volume on the acoustic behaviors of opened cavity system is studied.

The distribution of the scattered laser light in laser-plate-target coupling

NASA Astrophysics Data System (ADS)

Xiao-bo, Nie; Tie-qiang, Chang; Dong-xian, Lai; Shen-ye, Liu; Zhi-jian, Zheng

1997-04-01

Theoretical and experimental studies of the angular distributions of scattered laser light in laser-Au-plate-target coupling are reported. A simple model that describes three-dimensional plasmas and scattered laser light is presented. The approximate shape of critical density surface has been given and the three-dimensional laser ray tracing is applied in the model. The theoretical results of the model are consistent with the experimental data for the scattered laser light in the polar angle range of 25° to 145° from the laser beam.

Sputtering and ion plating for aerospace applications

NASA Technical Reports Server (NTRS)

Spalvins, T.

1981-01-01

Sputtering and ion plating technologies are reviewed in terms of their potential and present uses in the aerospace industry. Sputtering offers great universality and flexibility in depositing any material or in the synthesis of new ones. The sputter deposition process has two areas of interest: thin film and fabrication technology. Thin film sputtering technology is primarily used for aerospace mechanical components to reduce friction, wear, erosion, corrosion, high temperature oxidation, diffusion and fatigue, and also to sputter-construct temperature and strain sensors for aircraft engines. Sputter fabrication is used in intricate aircraft component manufacturing. Ion plating applications are discussed in terms of the high energy evaporant flux and the high throwing power. Excellent adherence and 3 dimensional coverage are the primary attributes of this technology.

Sputtering and ion plating for aerospace applications

NASA Technical Reports Server (NTRS)

Spalvins, T.

1981-01-01

Sputtering and ion plating technologies are reviewed in terms of their potential and present uses in the aerospace industry. Sputtering offers great universality and flexibility in depositing any material or in the synthesis of new ones. The sputter deposition process has two areas of interest: thin film and fabrication technology. Thin film sputtering technology is primarily used for aerospace mechanical components to reduce friction, wear, erosion, corrosion, high temperature oxidation, diffusion and fatigue, and also to sputter-construct temperature and strain sensors for aircraft engines. Sputter fabrication is used in intricate aircraft component manufacturing. Ion plating applications are discussed in terms of the high energy evaporant flux and the high throwing power. Excellent adherence and 3-dimensional coverage are the primary attributes of this technology.

High-performance parallel approaches for three-dimensional light detection and ranging point clouds gridding

NASA Astrophysics Data System (ADS)

Rizki, Permata Nur Miftahur; Lee, Heezin; Lee, Minsu; Oh, Sangyoon

2017-01-01

With the rapid advance of remote sensing technology, the amount of three-dimensional point-cloud data has increased extraordinarily, requiring faster processing in the construction of digital elevation models. There have been several attempts to accelerate the computation using parallel methods; however, little attention has been given to investigating different approaches for selecting the most suited parallel programming model for a given computing environment. We present our findings and insights identified by implementing three popular high-performance parallel approaches (message passing interface, MapReduce, and GPGPU) on time demanding but accurate kriging interpolation. The performances of the approaches are compared by varying the size of the grid and input data. In our empirical experiment, we demonstrate the significant acceleration by all three approaches compared to a C-implemented sequential-processing method. In addition, we also discuss the pros and cons of each method in terms of usability, complexity infrastructure, and platform limitation to give readers a better understanding of utilizing those parallel approaches for gridding purposes.

Three-dimensional aspects of radiative transfer in remote sensing of precipitation: Application to the 1986 COHMEX storm

NASA Technical Reports Server (NTRS)

Haferman, J. L.; Krajewski, W. F.; Smith, T. F.

1994-01-01

Several multifrequency techniques for passive microwave estimation of precipitation based on the absorption and scattering properties of hydrometers have been proposed in the literature. In the present study, plane-parallel limitations are overcome by using a model based on the discrete-ordinates method to solve the radiative transfer equation in three-dimensional rectangular domains. This effectively accounts for the complexity and variety of radiation problems encountered in the atmosphere. This investigation presents result for plane-parallel and three-dimensional radiative transfer for a precipitating system, discusses differences between these results, and suggests possible explanations for these differences. Microphysical properties were obtained from the Colorado State University Regional Atmospehric Modeling System and represent a hailstorm observed during the 1986 Cooperative Huntsville Meteorological Experiment. These properties are used as input to a three-dimensional radiative transfer model in order to simulate satellite observation of the storm. The model output consists of upwelling brightness temperatures at several of the frequencies on the Special Sensor Microwave/Imager. The radiative transfer model accounts for scattering and emission of atmospheric gases and hydrometers in liquid and ice phases. Brightness temperatures obtained from the three-dimensional model of this investigation indicate that horizontal inhomogeneities give rise to brightness temperature fields that can be quite different from fields obtained using plane-parallel radiative transfer theory. These differences are examined for various resolutions of the satellite sensor field of view. In adddition, the issue of boundary conditions for three-dimensional atmospheric radiative transfer is addressed.

Construction and comparison of parallel implicit kinetic solvers in three spatial dimensions

NASA Astrophysics Data System (ADS)

Titarev, Vladimir; Dumbser, Michael; Utyuzhnikov, Sergey

2014-01-01

The paper is devoted to the further development and systematic performance evaluation of a recent deterministic framework Nesvetay-3D for modelling three-dimensional rarefied gas flows. Firstly, a review of the existing discretization and parallelization strategies for solving numerically the Boltzmann kinetic equation with various model collision integrals is carried out. Secondly, a new parallelization strategy for the implicit time evolution method is implemented which improves scaling on large CPU clusters. Accuracy and scalability of the methods are demonstrated on a pressure-driven rarefied gas flow through a finite-length circular pipe as well as an external supersonic flow over a three-dimensional re-entry geometry of complicated aerodynamic shape.

Three-Dimensional Solution of the Free Vibration Problem for Metal-Ceramic Shells Using the Method of Sampling Surfaces

NASA Astrophysics Data System (ADS)

Kulikov, G. M.; Plotnikova, S. V.

2017-03-01

The possibility of using the method of sampling surfaces (SaS) for solving the free vibration problem of threedimensional elasticity for metal-ceramic shells is studied. According to this method, in the shell body, an arbitrary number of SaS parallel to its middle surface are selected in order to take displacements of these surfaces as unknowns. The SaS pass through the nodes of a Chebyshev polynomial, which improves the convergence of the SaS method significantly. As a result, the SaS method can be used to obtain analytical solutions of the vibration problem for metal-ceramic plates and cylindrical shells that asymptotically approach the exact solutions of elasticity as the number of SaS tends to infinity.

Experimental Observation of the Effects of Translational and Rotational Electrode Misalignment on a Planar Linear Ion Trap Mass Spectrometer

NASA Astrophysics Data System (ADS)

Tian, Yuan; Decker, Trevor K.; McClellan, Joshua S.; Wu, Qinghao; De la Cruz, Abraham; Hawkins, Aaron R.; Austin, Daniel E.

2018-04-01

The performance of miniaturized ion trap mass analyzers is limited, in part, by the accuracy with which electrodes can be fabricated and positioned relative to each other. Alignment of plates in a two-plate planar LIT is ideal to characterize misalignment effects, as it represents the simplest possible case, having only six degrees of freedom (DOF) (three translational and three rotational). High-precision motorized actuators were used to vary the alignment between the two ion trap plates in five DOFs—x, y, z, pitch, and yaw. A comparison between the experiment and previous simulations shows reasonable agreement. Pitch, or the degree to which the plates are parallel along the axial direction, has the largest and sharpest impact to resolving power, with resolving power dropping noticeably with pitch misalignment of a fraction of a degree. Lateral displacement (x) and yaw (rotation of one plate, but plates remain parallel) both have a strong impact on ion ejection efficiency, but little effect on resolving power. The effects of plate spacing (y-displacement) on both resolving power and ion ejection efficiency are attributable to higher-order terms in the trapping field. Varying the DC (axial) trapping potential can elucidate the effects where more misalignments in more than one DOF affect performance. Implications of these results for miniaturized ion traps are discussed. [Figure not available: see fulltext.

Hydrodynamic and Thermal Slip Effect on Double-Diffusive Free Convective Boundary Layer Flow of a Nanofluid Past a Flat Vertical Plate in the Moving Free Stream

PubMed Central

Khan, Waqar A.; Uddin, Md Jashim; Ismail, A. I. Md.

2013-01-01

The effects of hydrodynamic and thermal slip boundary conditions on the double-diffusive free convective flow of a nanofluid along a semi-infinite flat solid vertical plate are investigated numerically. It is assumed that free stream is moving. The governing boundary layer equations are non-dimensionalized and transformed into a system of nonlinear, coupled similarity equations. The effects of the controlling parameters on the dimensionless velocity, temperature, solute and nanofluid concentration as well as on the reduced Nusselt number, reduced Sherwood number and the reduced nanoparticle Sherwood number are investigated and presented graphically. To the best of our knowledge, the effects of hydrodynamic and thermal slip boundary conditions have not been investigated yet. It is found that the reduced local Nusselt, local solute and the local nanofluid Sherwood numbers increase with hydrodynamic slip and decrease with thermal slip parameters. PMID:23533566

Large-area assembly of three-dimensional nanoparticle structures via ion assisted aerosol lithography with a multi-pin spark discharge generator.

PubMed

Ha, Kyungyeon; Choi, Hoseop; Jung, Kinam; Han, Kyuhee; Lee, Jong-Kwon; Ahn, KwangJun; Choi, Mansoo

2014-06-06

We present an approach utilizing ion assisted aerosol lithography (IAAL) with a newly designed multi-pin spark discharge generator (SDG) for fabricating large-area three-dimensional (3D) nanoparticle-structure (NPS) arrays. The design of the multi-pin SDG allows us to uniformly construct 3D NPSs on a large area of 50 mm × 50 mm in a parallel fashion at atmospheric pressure. The ion-induced focusing capability of IAAL significantly reduces the feature size of 3D NPSs compared to that of the original pre-patterns formed on a substrate. The spatial uniformity of 3D NPSs is above 95% using the present multi-pin SDG, which is far superior to that of the previous single-pin SDG with less than 32% uniformity. The effect of size distributions of nanoparticles generated via the multi-pin SDG on the 3D NPSs also has been studied. In addition, we measured spectral reflectance for the present 3D NPSs coated with Ag, demonstrating enhanced diffuse reflectance.

Large-area assembly of three-dimensional nanoparticle structures via ion assisted aerosol lithography with a multi-pin spark discharge generator

NASA Astrophysics Data System (ADS)

Ha, Kyungyeon; Choi, Hoseop; Jung, Kinam; Han, Kyuhee; Lee, Jong-Kwon; Ahn, KwangJun; Choi, Mansoo

2014-06-01

We present an approach utilizing ion assisted aerosol lithography (IAAL) with a newly designed multi-pin spark discharge generator (SDG) for fabricating large-area three-dimensional (3D) nanoparticle-structure (NPS) arrays. The design of the multi-pin SDG allows us to uniformly construct 3D NPSs on a large area of 50 mm × 50 mm in a parallel fashion at atmospheric pressure. The ion-induced focusing capability of IAAL significantly reduces the feature size of 3D NPSs compared to that of the original pre-patterns formed on a substrate. The spatial uniformity of 3D NPSs is above 95% using the present multi-pin SDG, which is far superior to that of the previous single-pin SDG with less than 32% uniformity. The effect of size distributions of nanoparticles generated via the multi-pin SDG on the 3D NPSs also has been studied. In addition, we measured spectral reflectance for the present 3D NPSs coated with Ag, demonstrating enhanced diffuse reflectance.

Measurement of nanoscale three-dimensional diffusion in the interior of living cells by STED-FCS.

PubMed

Lanzanò, Luca; Scipioni, Lorenzo; Di Bona, Melody; Bianchini, Paolo; Bizzarri, Ranieri; Cardarelli, Francesco; Diaspro, Alberto; Vicidomini, Giuseppe

2017-07-06

The observation of molecular diffusion at different spatial scales, and in particular below the optical diffraction limit (<200 nm), can reveal details of the subcellular topology and its functional organization. Stimulated-emission depletion microscopy (STED) has been previously combined with fluorescence correlation spectroscopy (FCS) to investigate nanoscale diffusion (STED-FCS). However, stimulated-emission depletion fluorescence correlation spectroscopy has only been used successfully to reveal functional organization in two-dimensional space, such as the plasma membrane, while, an efficient implementation for measurements in three-dimensional space, such as the cellular interior, is still lacking. Here we integrate the STED-FCS method with two analytical approaches, the recent separation of photons by lifetime tuning and the fluorescence lifetime correlation spectroscopy, to simultaneously probe diffusion in three dimensions at different sub-diffraction scales. We demonstrate that this method efficiently provides measurement of the diffusion of EGFP at spatial scales tunable from the diffraction size down to ∼80 nm in the cytoplasm of living cells.The measurement of molecular diffusion at sub-diffraction scales has been achieved in 2D space using STED-FCS, but an implementation for 3D diffusion is lacking. Here the authors present an analytical approach to probe diffusion in 3D space using STED-FCS and measure the diffusion of EGFP at different spatial scales.

Casimir energy between two parallel plates and projective representation of the Poincaré group

NASA Astrophysics Data System (ADS)

Akita, Takamaru; Matsunaga, Mamoru

2016-06-01

The Casimir effect is a physical manifestation of zero point energy of quantum vacuum. In a relativistic quantum field theory, Poincaré symmetry of the theory seems, at first sight, to imply that nonzero vacuum energy is inconsistent with translational invariance of the vacuum. In the setting of two uniform boundary plates at rest, quantum fields outside the plates have (1 +2 )-dimensional Poincaré symmetry. Taking a massless scalar field as an example, we have examined the consistency between the Poincaré symmetry and the existence of the vacuum energy. We note that, in quantum theory, symmetries are represented projectively in general and show that the Casimir energy is connected to central charges appearing in the algebra of generators in the projective representations.

The Proof of the ``Vortex Theory of Matter''

NASA Astrophysics Data System (ADS)

Moon, Russell

2009-11-01

According to the Vortex Theory, protons and electrons are three-dimensional holes connected by fourth-dimensional vortices. It was further theorized that when photons are absorbed then readmitted by atoms, the photon is absorbed into the proton, moves through the fourth-dimensional vortex, then reemerges back into three-dimensional space through the electron. To prove this hypothesis, an experiment was conducted using a hollow aluminum sphere containing a powerful permanent magnet suspended directly above a zinc plate. Ultraviolet light was then shined upon the zinc. The zinc emits electrons via the photoelectric effect that are attracted to the surface of the aluminum sphere. The sphere was removed from above the zinc plate and repositioned above a sensitive infrared digital camera in another room. The ball and camera were placed within a darkened box inside a Faraday cage. Light was shined upon the zinc plate and the picture taken by the camera was observed. When the light was turned on above the zinc plate in one room, the camera recorded increased light coming from the surface of the sphere within the other room; when the light was turned off, the intensity of the infrared light coming from the surface of the sphere was suddenly diminished. Five other tests were then performed to eliminate other possible explanations such as quantum-entangled electrons.

The Proof of the ``Vortex Theory of Matter''

NASA Astrophysics Data System (ADS)

Gridnev, Konstantin; Moon, Russell; Vasiliev, Victor

2009-11-01

According to the Vortex Theory, protons and electrons are three-dimensional holes connected by fourth-dimensional vortices. It was further theorized that when photons are absorbed then readmitted by atoms, the photon is absorbed into the proton, moves through the fourth-dimensional vortex, then reemerges back into three-dimensional space through the electron^2. To prove this hypothesis, an experiment was conducted using a hollow aluminum sphere containing a powerful permanent magnet suspended directly above a zinc plate. Ultraviolet light was then shined upon the zinc. The zinc emits electrons via the photoelectric effect that are attracted to the surface of the aluminum sphere. The sphere was removed from above the zinc plate and repositioned above a sensitive infrared digital camera in another room. The ball and camera were placed within a darkened box inside a Faraday cage. Light was shined upon the zinc plate and the picture taken by the camera was observed. When the light was turned on above the zinc plate in one room, the camera recorded increased light coming from the surface of the sphere within the other room; when the light was turned off, the intensity of the infrared light coming from the surface of the sphere was suddenly diminished. Five other tests were then performed to eliminate other possible explanations such as quantum-entangled electrons.

The Proof of the ``Vortex Theory of Matter''

NASA Astrophysics Data System (ADS)

Gridnev, Konstantin; Moon, Russell; Vasiliev, Victor

2009-10-01

According to the Vortex Theory, protons and electrons are three-dimensional holes connected by fourth-dimensional vortices. It was further theorized that when photons are absorbed then readmitted by atoms, the photon is absorbed into the proton, moves through the fourth-dimensional vortex, then reemerges back into three-dimensional space through the electron^2. To prove this hypothesis, an experiment was conducted using a hollow aluminum sphere containing a powerful permanent magnet suspended directly above a zinc plate. Ultraviolet light was then shined upon the zinc. The zinc emits electrons via the photoelectric effect that are attracted to the surface of the aluminum sphere. The sphere was removed from above the zinc plate and repositioned above a sensitive infrared digital camera in another room. The ball and camera were placed within a darkened box inside a Faraday cage. Light was shined upon the zinc plate and the picture taken by the camera was observed. When the light was turned on above the zinc plate in one room, the camera recorded increased light coming from the surface of the sphere within the other room; when the light was turned off, the intensity of the infrared light coming from the surface of the sphere was suddenly diminished. Five other tests were then performed to eliminate other possible explanations such as quantum-entangled electrons.

The Proof of the ``Vortex Theory of Matter''

NASA Astrophysics Data System (ADS)

Moon, Russell; Gridnev, Konstantin; Vasiliev, Victor

2010-02-01

According to the Vortex Theory, protons and electrons are three-dimensional holes connected by fourth-dimensional vortices. It was further theorized that when photons are absorbed then readmitted by atoms, the photon is absorbed into the proton, moves through the fourth-dimensional vortex, then reemerges back into three-dimensional space through the electron. To prove this hypothesis, an experiment was conducted using a hollow aluminum sphere containing a powerful permanent magnet suspended directly above a zinc plate. Ultraviolet light was then shined upon the zinc. The zinc emits electrons via the photoelectric effect that are attracted to the surface of the aluminum sphere. The sphere was removed from above the zinc plate and repositioned above a sensitive infrared digital camera in another room. The ball and camera were placed within a darkened box inside a Faraday cage. Light was shined upon the zinc plate and the picture taken by the camera was observed. When the light was turned on above the zinc plate in one room, the camera recorded increased light coming from the surface of the sphere within the other room; when the light was turned off, the intensity of the infrared light coming from the surface of the sphere was suddenly diminished. Five other tests were then performed to eliminate other possible explanations such as quantum-entangled electrons. )

Stresses and strains in thick perforated orthotropic plates

Treesearch

A. Alshaya; John Hunt; R. Rowlands

2016-01-01

Stress and strain concentrations and in-plane and out-of-plane stress constraint factors associated with a circular hole in thick, loaded orthotropic composite plates are determined by three-dimensional finite element method. The plate has essentially infinite in-plane geometry but finite thickness. Results for Sitka Spruce wood are emphasized, although some for carbon...

Influence of rheology on realignment of mantle convective structure with plate motion after a plate reorganization

NASA Astrophysics Data System (ADS)

van Hunen, J.; Zhong, S.

2006-08-01

Small-scale convection (SSC) rolls below the oceanic lithosphere have the tendency to align with the large-scale shearing direction and thus with the plate motion direction relative to the deep mantle. Understanding the timescales of and processes responsible for realignment would contribute significantly to our understanding of the unresolved phenomena in the Pacific such as gravity lineations, small-scale seismic velocity variations, and intraplate volcanism that cannot be explained by hot spots. In this study we examine the evolution of those convection rolls when this relative plate motion direction is suddenly changed, as suggested by the kink in the Hawaii-Emperor seamount chain. Using three-dimensional numerical flow models, we investigate the realignment of SSC rolls after a change in plate motion direction. From the nature of the SSC, it is expected that rheological parameters dominate the characteristics of this realignment. Our results show that this is indeed the case. We find that (1) using constraints from onset timing of SSC, realignment of rolls can occur as fast as within 20 Ma, but might also take much longer, dependent on the rheology; (2) the realignment period is strongly correlated to the sum of large-scale shear stress induced by plate motion and small-scale shear stress from the SSC itself; (3) in a mantle deforming by dislocation creep, realignment occurs faster than by diffusion creep, because dislocation creep SSC is more vigorous; and (4) activation energy has little influence on the realignment time. Possible evidence for the realignment period might come from precise age determination of intraplate volcanism or azimuthal seismic anisotropy.

Numerical investigation of the self-starting of a vertical axis wind turbine

NASA Astrophysics Data System (ADS)

Tsai, Hsieh-Chen; Colonius, Tim

2014-11-01

The immersed boundary method is used to simulate the incompressible flow around two-dimensional airfoils at sub-scale Reynolds number in order to investigate the self-starting capability of a vertical-axis wind turbine (VAWT). By investigating a single blade fixed at various angle of attacks, the leading edge vortex (LEV) is shown to play an important role in the starting mechanism for both flat-plate and NACA 0018 blades. Depending on the angle of attack of the blade, as the LEV grows, the corresponding low pressure region results in a thrust in the tangential direction, which produces a positive torque to VAWT. Due to the characteristics of the blades, a NACA 0018 blade produces a larger thrust over a wider range of angle of attacks than a flat-plate blade. Therefore, a VAWT with NACA 0018 blades can self-start more easily than one with flat-plate blades. Moreover, by investigating the starting torque of three-bladed VAWTs fixed at various orientations, the optimal orientation that produces the largest torque to start both VAWTs is with a blade parallel to the flow and facing downstream. The simulations are also compared to results from companion water-tunnel experiments at Caltech. This project is supported by Caltech FLOWE center/Gordon and Betty Moore Foundation.

Multiscale modeling and simulation for polymer melt flows between parallel plates

NASA Astrophysics Data System (ADS)

Yasuda, Shugo; Yamamoto, Ryoichi

2010-03-01

The flow behaviors of polymer melt composed of short chains with ten beads between parallel plates are simulated by using a hybrid method of molecular dynamics and computational fluid dynamics. Three problems are solved: creep motion under a constant shear stress and its recovery motion after removing the stress, pressure-driven flows, and the flows in rapidly oscillating plates. In the creep/recovery problem, the delayed elastic deformation in the creep motion and evident elastic behavior in the recovery motion are demonstrated. The velocity profiles of the melt in pressure-driven flows are quite different from those of Newtonian fluid due to shear thinning. Velocity gradients of the melt become steeper near the plates and flatter at the middle between the plates as the pressure gradient increases and the temperature decreases. In the rapidly oscillating plates, the viscous boundary layer of the melt is much thinner than that of Newtonian fluid due to the shear thinning of the melt. Three different rheological regimes, i.e., the viscous fluid, viscoelastic liquid, and viscoelastic solid regimes, form over the oscillating plate according to the local Deborah numbers. The melt behaves as a viscous fluid in a region for ωτR≲1 , and the crossover between the liquidlike and solidlike regime takes place around ωτα≃1 (where ω is the angular frequency of the plate and τR and τα are Rouse and α relaxation time, respectively).

Multiscale modeling and simulation for polymer melt flows between parallel plates.

PubMed

Yasuda, Shugo; Yamamoto, Ryoichi

2010-03-01

The flow behaviors of polymer melt composed of short chains with ten beads between parallel plates are simulated by using a hybrid method of molecular dynamics and computational fluid dynamics. Three problems are solved: creep motion under a constant shear stress and its recovery motion after removing the stress, pressure-driven flows, and the flows in rapidly oscillating plates. In the creep/recovery problem, the delayed elastic deformation in the creep motion and evident elastic behavior in the recovery motion are demonstrated. The velocity profiles of the melt in pressure-driven flows are quite different from those of Newtonian fluid due to shear thinning. Velocity gradients of the melt become steeper near the plates and flatter at the middle between the plates as the pressure gradient increases and the temperature decreases. In the rapidly oscillating plates, the viscous boundary layer of the melt is much thinner than that of Newtonian fluid due to the shear thinning of the melt. Three different rheological regimes, i.e., the viscous fluid, viscoelastic liquid, and viscoelastic solid regimes, form over the oscillating plate according to the local Deborah numbers. The melt behaves as a viscous fluid in a region for omegatauR < approximately 1 , and the crossover between the liquidlike and solidlike regime takes place around omegataualpha approximately equal 1 (where omega is the angular frequency of the plate and tauR and taualpha are Rouse and alpha relaxation time, respectively).

Three-dimensional anisotropy contrast periodically rotated overlapping parallel lines with enhanced reconstruction (3DAC PROPELLER) on a 3.0T system: a new modality for routine clinical neuroimaging.

PubMed

Nakada, Tsutomu; Matsuzawa, Hitoshi; Fujii, Yukihiko; Takahashi, Hitoshi; Nishizawa, Masatoyo; Kwee, Ingrid L

2006-07-01

Clinical magnetic resonance imaging (MRI) has recently entered the "high-field" era, and systems equipped with 3.0-4.0T superconductive magnets are becoming the gold standard for diagnostic imaging. While higher signal-to-noise ratio (S/N) is a definite advantage of higher field systems, higher susceptibility effect remains to be a significant trade-off. To take advantage of a higher field system in performing routine clinical images of higher anatomical resolution, we implemented a vector contrast image technique to 3.0T imaging, three-dimensional anisotropy contrast (3DAC), with a PROPELLER (Periodically Rotated Overlapping Parallel Lines with Enhanced Reconstruction) sequence, a method capable of effectively eliminating undesired artifacts on rapid diffusion imaging sequences. One hundred subjects (20 normal volunteers and 80 volunteers with various central nervous system diseases) participated in the study. Anisotropic diffusion-weighted PROPELLER images were obtained on a General Electric (Waukesha, WI, USA) Signa 3.0T for each axis, with b-value of 1100 sec/mm(2). Subsequently, 3DAC images were constructed using in-house software written on MATLAB (MathWorks, Natick, MA, USA). The vector contrast allows for providing exquisite anatomical detail illustrated by clear identification of all major tracts through the entire brain. 3DAC images provide better anatomical resolution for brainstem glioma than higher-resolution T2 reversed images. Degenerative processes of disease-specific tracts were clearly identified as illustrated in cases of multiple system atrophy and Joseph-Machado disease. Anatomical images of significantly higher resolution than the best current standard, T2 reversed images, were successfully obtained. As a technique readily applicable under routine clinical setting, 3DAC PROPELLER on a 3.0T system will be a powerful addition to diagnostic imaging.

Multilayer based lab-on-a-chip-systems for substance testing

NASA Astrophysics Data System (ADS)

Sonntag, Frank; Grünzner, Stefan; Schmieder, Florian; Busek, Mathias; Klotzbach, Udo; Franke, Volker

2015-03-01

An integrated technology chain for laser-microstructuring and bonding of polymer foils for fast, flexible and low-cost manufacturing of multilayer lab-on-a-chip devices especially for complex cell and tissue culture applications, which provides pulsatile fluid flow within physiological ranges at low media-to-cells ratio, was developed and established. Initially the microfluidic system is constructively divided into individual layers which are formed by separate foils or plates. Based on the functional boundary conditions and the necessary properties of each layer the corresponding foils and plates are chosen. In the third step the foils and plates are laser microstructured and functionalized from both sides. In the fourth and last manufacturing step the multiple plates and foils are joined using thermal diffusion bonding. Membranes for pneumatically driven valves and micropumps where bonded via chemical surface modification. Based on the established lab-on-a-chip platform for perfused cell-based assays, a multilayer microfluidic system with two parallel connected cell culture chambers was successfully implemented.

3D vortex formation of drag-based propulsors

NASA Astrophysics Data System (ADS)

Kim, Daegyoum; Gharib, Morteza

2008-11-01

Three dimensional vortex formation mechanism of impulsively rotating plates is studied experimentally using defocusing digital particle image velocimetry. The plate face is normal to the moving direction to simulate drag-based propulsion and only one power stroke is considered. In order to compare the effect of shape on vortex generation, three different shapes of plate (rectangular, triangular and duck's webbed-foot shapes) are used. These three cases show striking differences in vortex formation process during power stroke. Axial flow is shown to play an important role in the tip vortex formation. Correlation between hydrodynamic forces acting on the plate and vortex formation processes is described.

A Novel Multi-scale Simulation Strategy for Turbulent Reacting Flows

DOE Office of Scientific and Technical Information (OSTI.GOV)

James, Sutherland C.

In this project, a new methodology was proposed to bridge the gap between Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES). This novel methodology, titled Lattice-Based Multiscale Simulation (LBMS), creates a lattice structure of One-Dimensional Turbulence (ODT) models. This model has been shown to capture turbulent combustion with high fidelity by fully resolving interactions between turbulence and diffusion. By creating a lattice of ODT models, which are then coupled, LBMS overcomes the shortcomings of ODT, which are its inability to capture large scale three dimensional flow structures. However, by spacing these lattices significantly apart, LBMS can avoid the cursemore » of dimensionality that creates untenable computational costs associated with DNS. This project has shown that LBMS is capable of reproducing statistics of isotropic turbulent flows while coarsening the spacing between lines significantly. It also investigates and resolves issues that arise when coupling ODT lines, such as flux reconstruction perpendicular to a given ODT line, preservation of conserved quantities when eddies cross a course cell volume and boundary condition application. Robust parallelization is also investigated.« less

Global isostatic geoid anomalies for plate and boundary layer models of the lithosphere

NASA Technical Reports Server (NTRS)

Hager, B. H.

1981-01-01

Commonly used one dimensional geoid models predict that the isostatic geoid anomaly over old ocean basins for the boundary layer thermal model of the lithosphere is a factor of two greater than that for the plate model. Calculations presented, using the spherical analogues of the plate and boundary layer thermal models, show that for the actual global distribution of plate ages, one dimensional models are not accurate and a spherical, fully three dimensional treatment is necessary. The maximum difference in geoid heights predicted for the two models is only about two meters. The thermal structure of old lithosphere is unlikely to be resolvable using global geoid anomalies. Stripping the effects of plate aging and a hypothetical uniform, 35 km, isostatically-compensated continental crust from the observed geoid emphasizes that the largest-amplitude geoid anomaly is the geoid low of almost 120 m over West Antarctica, a factor of two greater than the low of 60 m over Ceylon.

Rapid Prediction of Unsteady Three-Dimensional Viscous Flows in Turbopump Geometries

NASA Technical Reports Server (NTRS)

Dorney, Daniel J.

1998-01-01

A program is underway to improve the efficiency of a three-dimensional Navier-Stokes code and generalize it for nozzle and turbopump geometries. Code modifications will include the implementation of parallel processing software, incorporating new physical models and generalizing the multi-block capability to allow the simultaneous simulation of nozzle and turbopump configurations. The current report contains details of code modifications, numerical results of several flow simulations and the status of the parallelization effort.

Numerical simulations of human tibia osteosynthesis using modular plates based on Nitinol staples.

PubMed

Tarniţă, Daniela; Tarniţă, D N; Popa, D; Grecu, D; Tarniţă, Roxana; Niculescu, D; Cismaru, F

2010-01-01

The shape memory alloys exhibit a number of remarkable properties, which open new possibilities in engineering and more specifically in biomedical engineering. The most important alloy used in biomedical applications is NiTi. This alloy combines the characteristics of the shape memory effect and superelasticity with excellent corrosion resistance, wear characteristics, mechanical properties and a good biocompatibility. These properties make it an ideal biological engineering material, especially in orthopedic surgery and orthodontics. In this work, modular plates for the osteosynthesis of the long bones fractures are presented. The proposed modular plates are realized from identical modules, completely interchangeable, made of titanium or stainless steel having as connecting elements U-shaped staples made of Nitinol. Using computed tomography (CT) images to provide three-dimensional geometric details and SolidWorks software package, the three dimensional virtual models of the tibia bone and of the modular plates are obtained. The finite element models of the tibia bone and of the modular plate are generated. For numerical simulation, VisualNastran software is used. Finally, displacements diagram, von Misses strain diagram, for the modular plate and for the fractured tibia and modular plate ensemble are obtained.

Performance analysis of three dimensional integral equation computations on a massively parallel computer. M.S. Thesis

NASA Technical Reports Server (NTRS)

Logan, Terry G.

1994-01-01

The purpose of this study is to investigate the performance of the integral equation computations using numerical source field-panel method in a massively parallel processing (MPP) environment. A comparative study of computational performance of the MPP CM-5 computer and conventional Cray-YMP supercomputer for a three-dimensional flow problem is made. A serial FORTRAN code is converted into a parallel CM-FORTRAN code. Some performance results are obtained on CM-5 with 32, 62, 128 nodes along with those on Cray-YMP with a single processor. The comparison of the performance indicates that the parallel CM-FORTRAN code near or out-performs the equivalent serial FORTRAN code for some cases.

Fringe Capacitance of a Parallel-Plate Capacitor.

ERIC Educational Resources Information Center

Hale, D. P.

1978-01-01

Describes an experiment designed to measure the forces between charged parallel plates, and determines the relationship among the effective electrode area, the measured capacitance values, and the electrode spacing of a parallel plate capacitor. (GA)

A four-dimensional variational chemistry data assimilation scheme for Eulerian chemistry transport modeling

NASA Astrophysics Data System (ADS)

Eibern, Hendrik; Schmidt, Hauke

1999-08-01

The inverse problem of data assimilation of tropospheric trace gas observations into an Eulerian chemistry transport model has been solved by the four-dimensional variational technique including chemical reactions, transport, and diffusion. The University of Cologne European Air Pollution Dispersion Chemistry Transport Model 2 with the Regional Acid Deposition Model 2 gas phase mechanism is taken as the basis for developing a full four-dimensional variational data assimilation package, on the basis of the adjoint model version, which includes the adjoint operators of horizontal and vertical advection, implicit vertical diffusion, and the adjoint gas phase mechanism. To assess the potential and limitations of the technique without degrading the impact of nonperfect meteorological analyses and statistically not established error covariance estimates, artificial meteorological data and observations are used. The results are presented on the basis of a suite of experiments, where reduced records of artificial "observations" are provided to the assimilation procedure, while other "data" is retained for performance control of the analysis. The paper demonstrates that the four-dimensional variational technique is applicable for a comprehensive chemistry transport model in terms of computational and storage requirements on advanced parallel platforms. It is further shown that observed species can generally be analyzed, even if the "measurements" have unbiased random errors. More challenging experiments are presented, aiming to tax the skill of the method (1) by restricting available observations mostly to surface ozone observations for a limited assimilation interval of 6 hours and (2) by starting with poorly chosen first guess values. In this first such application to a three-dimensional chemistry transport model, success was also achieved in analyzing not only observed but also chemically closely related unobserved constituents.

Massively parallel GPU-accelerated minimization of classical density functional theory

NASA Astrophysics Data System (ADS)

Stopper, Daniel; Roth, Roland

2017-08-01

In this paper, we discuss the ability to numerically minimize the grand potential of hard disks in two-dimensional and of hard spheres in three-dimensional space within the framework of classical density functional and fundamental measure theory on modern graphics cards. Our main finding is that a massively parallel minimization leads to an enormous performance gain in comparison to standard sequential minimization schemes. Furthermore, the results indicate that in complex multi-dimensional situations, a heavy parallel minimization of the grand potential seems to be mandatory in order to reach a reasonable balance between accuracy and computational cost.

On the motion of viscous fluids in the presence of diffusion

NASA Astrophysics Data System (ADS)

Secchi, Paolo

1988-01-01

The flow of a viscous incompressible two-component fluid with Fick's-law diffusion is investigated analytically. The existence of a unique global solution for small values of the diffusion coefficient (lambda) is proved for two-dimensional flow. The two- and three-dimensional solutions are also shown to converge toward the solutions of the Navier-Stokes equations for inhomogeneous fluids as lambda approaches zero.

Three-dimensional cellular automata as a model of a seismic fault

NASA Astrophysics Data System (ADS)

Gálvez, G.; Muñoz, A.

2017-01-01

The Earth's crust is broken into a series of plates, whose borders are the seismic fault lines and it is where most of the earthquakes occur. This plating system can in principle be described by a set of nonlinear coupled equations describing the motion of the plates, its stresses, strains and other characteristics. Such a system of equations is very difficult to solve, and nonlinear parts leads to a chaotic behavior, which is not predictable. In 1989, Bak and Tang presented an earthquake model based on the sand pile cellular automata. The model though simple, provides similar results to those observed in actual earthquakes. In this work the cellular automata in three dimensions is proposed as a best model to approximate a seismic fault. It is noted that the three-dimensional model reproduces similar properties to those observed in real seismicity, especially, the Gutenberg-Richter law.

Analytical modeling of operating characteristics of premixing-prevaporizing fuel-air mixing passages. Volume 1: Analysis and results

NASA Technical Reports Server (NTRS)

Anderson, O. L.; Chiappetta, L. M.; Edwards, D. E.; Mcvey, J. B.

1982-01-01

A model for predicting the distribution of liquid fuel droplets and fuel vapor in premixing-prevaporizing fuel-air mixing passages of the direct injection type is reported. This model consists of three computer programs; a calculation of the two dimensional or axisymmetric air flow field neglecting the effects of fuel; a calculation of the three dimensional fuel droplet trajectories and evaporation rates in a known, moving air flow; a calculation of fuel vapor diffusing into a moving three dimensional air flow with source terms dependent on the droplet evaporation rates. The fuel droplets are treated as individual particle classes each satisfying Newton's law, a heat transfer, and a mass transfer equation. This fuel droplet model treats multicomponent fuels and incorporates the physics required for the treatment of elastic droplet collisions, droplet shattering, droplet coalescence and droplet wall interactions. The vapor diffusion calculation treats three dimensional, gas phase, turbulent diffusion processes. The analysis includes a model for the autoignition of the fuel air mixture based upon the rate of formation of an important intermediate chemical species during the preignition period.

Design and analysis of all-dielectric broadband nonpolarizing parallel-plate beam splitters.

PubMed

Wang, Wenliang; Xiong, Shengming; Zhang, Yundong

2007-06-01

Past research on the all-dielectric nonpolarizing beam splitter is reviewed. With the aid of the needle thin-film synthesis method and the conjugate graduate refine method, three different split ratio nonpolarizing parallel-plate beam splitters over a 200 nm spectral range centered at 550 nm with incidence angles of 45 degrees are designed. The chosen materials component and the initial stack are based on the Costich and Thelen theories. The results of design and analysis show that the designs maintain a very low polarization ratio in the working range of the spectrum and has a reasonable angular field.

All-dielectric broadband non-polarizing parallel plate beam splitter operating between 450-650nm

NASA Astrophysics Data System (ADS)

Wang, Wenliang; Xiong, Shenming; Zhang, Yundong

2007-12-01

Past research on all-dielectric non-polarizing beam splitter is reviewed. With the aid of needle thin film synthesis method and conjugate graduate refining method, three non-polarizing parallel plate beam splitters with different split ratios over a 200nm spectral range centered at 550nm with incidence angle 45° are designed. Selection of material components and initial stack are based on Costich and Thelen's theory. The results of design and analysis show that it maintains a very low polarization ratio in the working range of spectrum and has a reasonable angular field.

Magnetospheric Multiscale Satellites Observations of Parallel Electric Fields Associated with Magnetic Reconnection.

PubMed

Ergun, R E; Goodrich, K A; Wilder, F D; Holmes, J C; Stawarz, J E; Eriksson, S; Sturner, A P; Malaspina, D M; Usanova, M E; Torbert, R B; Lindqvist, P-A; Khotyaintsev, Y; Burch, J L; Strangeway, R J; Russell, C T; Pollock, C J; Giles, B L; Hesse, M; Chen, L J; Lapenta, G; Goldman, M V; Newman, D L; Schwartz, S J; Eastwood, J P; Phan, T D; Mozer, F S; Drake, J; Shay, M A; Cassak, P A; Nakamura, R; Marklund, G

2016-06-10

We report observations from the Magnetospheric Multiscale satellites of parallel electric fields (E_{∥}) associated with magnetic reconnection in the subsolar region of the Earth's magnetopause. E_{∥} events near the electron diffusion region have amplitudes on the order of 100  mV/m, which are significantly larger than those predicted for an antiparallel reconnection electric field. This Letter addresses specific types of E_{∥} events, which appear as large-amplitude, near unipolar spikes that are associated with tangled, reconnected magnetic fields. These E_{∥} events are primarily in or near a current layer near the separatrix and are interpreted to be double layers that may be responsible for secondary reconnection in tangled magnetic fields or flux ropes. These results are telling of the three-dimensional nature of magnetopause reconnection and indicate that magnetopause reconnection may be often patchy and/or drive turbulence along the separatrix that results in flux ropes and/or tangled magnetic fields.

First Results from a Forward, 3-Dimensional Regional Model of a Transpressional San Andreas Fault System

NASA Astrophysics Data System (ADS)

Fitzenz, D. D.; Miller, S. A.

2001-12-01

We present preliminary results from a 3-dimensional fault interaction model, with the fault system specified by the geometry and tectonics of the San Andreas Fault (SAF) system. We use the forward model for earthquake generation on interacting faults of Fitzenz and Miller [2001] that incorporates the analytical solutions of Okada [85,92], GPS-constrained tectonic loading, creep compaction and frictional dilatancy [Sleep and Blanpied, 1994, Sleep, 1995], and undrained poro-elasticity. The model fault system is centered at the Big Bend, and includes three large strike-slip faults (each discretized into multiple subfaults); 1) a 300km, right-lateral segment of the SAF to the North, 2) a 200km-long left-lateral segment of the Garlock fault to the East, and 3) a 100km-long right-lateral segment of the SAF to the South. In the initial configuration, three shallow-dipping faults are also included that correspond to the thrust belt sub-parallel to the SAF. Tectonic loading is decomposed into basal shear drag parallel to the plate boundary with a 35mm yr-1 plate velocity, and East-West compression approximated by a vertical dislocation surface applied at the far-field boundary resulting in fault-normal compression rates in the model space about 4mm yr-1. Our aim is to study the long-term seismicity characteristics, tectonic evolution, and fault interaction of this system. We find that overpressured faults through creep compaction are a necessary consequence of the tectonic loading, specifically where high normal stress acts on long straight fault segments. The optimal orientation of thrust faults is a function of the strike-slip behavior, and therefore results in a complex stress state in the elastic body. This stress state is then used to generate new fault surfaces, and preliminary results of dynamically generated faults will also be presented. Our long-term aim is to target measurable properties in or around fault zones, (e.g. pore pressures, hydrofractures, seismicity catalogs, stress orientation, surface strain, triggering, etc.), which may allow inferences on the stress state of fault systems.

Stress wave calculations in composite plates using the fast Fourier transform.

NASA Technical Reports Server (NTRS)

Moon, F. C.

1973-01-01

The protection of composite turbine fan blades against impact forces has prompted the study of dynamic stresses in composites due to transient loads. The mathematical model treats the laminated plate as an equivalent anisotropic material. The use of Mindlin's approximate theory of crystal plates results in five two-dimensional stress waves. Three of the waves are flexural and two involve in-plane extensional strains. The initial value problem due to a transient distributed transverse force on the plate is solved using Laplace and Fourier transforms. A fast computer program for inverting the two-dimensional Fourier transform is used. Stress contours for various stresses and times after application of load are obtained for a graphite fiber-epoxy matrix composite plate. Results indicate that the points of maximum stress travel along the fiber directions.

Stress concentrations for straight-shank and countersunk holes in plates subjected to tension, bending, and pin loading

NASA Technical Reports Server (NTRS)

Shivakumar, K. N.; Newman, J. C., Jr.

1992-01-01

A three dimensional stress concentration analysis was conducted on straight shank and countersunk (rivet) holes in a large plate subjected to various loading conditions. Three dimensional finite element analysis were performed with 20 node isoparametric elements. The plate material was assumed to be linear elastic and isotropic, with a Poisson ratio of 0.3. Stress concentration along the bore of the hole were computed for several ratios of hole radius to plate thickness (0.1 to 2.5) and ratios of countersink depth to plate thickness (0.25 to 1). The countersink angles were varied from 80 to 100 degrees in some typical cases, but the angle was held constant at 100 degrees for most cases. For straight shank holes, three types of loading were considered: remote tension, remote bending, and wedge loading in the hole. Results for remote tension and wedge loading were used to estimate stress concentration for simulated rivet in pin loading. For countersunk holes only remote tension and bending were considered. Based on the finite element results, stress concentration equations were developed. Whenever possible, the present results were compared with other numerical solutions and experimental results from the literature.

Air cycle machine for an aircraft environmental control system

NASA Technical Reports Server (NTRS)

Decrisantis, Angelo A. (Inventor); O'Coin, James R. (Inventor); Taddey, Edmund P. (Inventor)

2010-01-01

An ECS system includes an ACM mounted adjacent an air-liquid heat exchanger through a diffuser that contains a diffuser plate. The diffuser plate receives airflow from the ACM which strikes the diffuser plate and flows radially outward and around the diffuser plate and into the air-liquid heat exchanger to provide minimal pressure loss and proper flow distribution into the air-liquid heat exchanger with significantly less packaging space.

Self-diffusion in a stochastically heated two-dimensional dusty plasma

NASA Astrophysics Data System (ADS)

Sheridan, T. E.

2016-09-01

Diffusion in a two-dimensional dusty plasma liquid (i.e., a Yukawa liquid) is studied experimentally. The dusty plasma liquid is heated stochastically by a surrounding three-dimensional toroidal dusty plasma gas which acts as a thermal reservoir. The measured dust velocity distribution functions are isotropic Maxwellians, giving a well-defined kinetic temperature. The mean-square displacement for dust particles is found to increase linearly with time, indicating normal diffusion. The measured diffusion coefficients increase approximately linearly with temperature. The effective collision rate is dominated by collective dust-dust interactions rather than neutral gas drag, and is comparable to the dusty-plasma frequency.

Surface flatness measurement of quasi-parallel plates employing three-beam interference with strong reference beam

NASA Astrophysics Data System (ADS)

Sunderland, Zofia; Patorski, Krzysztof

2016-12-01

A big challenge for standard interferogram analysis methods such as Temporal Phase Shifting or Fourier Transform is a parasitic set of fringes which might occur in the analyzed fringe pattern intensity distribution. It is encountered, for example, when transparent glass plates with quasi-parallel surfaces are tested in Fizeau or Twyman-Green interferometers. Besides the beams reflected from the plate front surface and the interferometer reference the beam reflected from the plate rear surface also plays important role; its amplitude is comparable with the amplitude of other beams. In result we face three families of fringes of high contrast which cannot be easily separated. Earlier we proposed a competitive solution for flatness measurements which relies on eliminating one of those fringe sets from the three-beam interferogram and separating two remaining ones with the use of 2D Continuous Wavelet Transform. In this work we cover the case when the intensity of the reference beam is significantly higher than the intensities of two object beams. The main advantage of differentiating beam intensities is the change in contrast of individual fringe families. Processing of such three-beam interferograms is modified but also takes advantage of 2D CWT. We show how to implement this method in Twyman-Green and Fizeau setups and compare this processing path and measurement procedures with previously proposed solutions.

On the Transition from Two-Dimensional to Three-Dimensional MHD Turbulence

NASA Technical Reports Server (NTRS)

Thess, A.; Zikanov, Oleg

2004-01-01

We report a theoretical investigation of the robustness of two-dimensional inviscid MHD flows at low magnetic Reynolds numbers with respect to three-dimensional perturbations. We analyze three model problems, namely flow in the interior of a triaxial ellipsoid, an unbounded vortex with elliptical streamlines, and a vortex sheet parallel to the magnetic field. We demonstrate that motion perpendicular to the magnetic field with elliptical streamlines becomes unstable with respect to the elliptical instability once the velocity has reached a critical magnitude whose value tends to zero as the eccentricity of the streamlines becomes large. Furthermore, vortex sheets parallel to the magnetic field, which are unstable for any velocity and any magnetic field, are found to emit eddies with vorticity perpendicular to the magnetic field and with an aspect ratio proportional to N(sup 1/2). The results suggest that purely two-dimensional motion without Joule energy dissipation is a singular type of flow which does not represent the asymptotic behaviour of three-dimensional MHD turbulence in the limit of infinitely strong magnetic fields.

Additivity Principle in High-Dimensional Deterministic Systems

NASA Astrophysics Data System (ADS)

Saito, Keiji; Dhar, Abhishek

2011-12-01

The additivity principle (AP), conjectured by Bodineau and Derrida [Phys. Rev. Lett. 92, 180601 (2004)PRLTAO0031-900710.1103/PhysRevLett.92.180601], is discussed for the case of heat conduction in three-dimensional disordered harmonic lattices to consider the effects of deterministic dynamics, higher dimensionality, and different transport regimes, i.e., ballistic, diffusive, and anomalous transport. The cumulant generating function (CGF) for heat transfer is accurately calculated and compared with the one given by the AP. In the diffusive regime, we find a clear agreement with the conjecture even if the system is high dimensional. Surprisingly, even in the anomalous regime the CGF is also well fitted by the AP. Lower-dimensional systems are also studied and the importance of three dimensionality for the validity is stressed.

Electrodeposition of Zn and Cu-Zn alloy from ZnO/CuO precursors in deep eutectic solvent

NASA Astrophysics Data System (ADS)

Xie, Xueliang; Zou, Xingli; Lu, Xionggang; Lu, Changyuan; Cheng, Hongwei; Xu, Qian; Zhou, Zhongfu

2016-11-01

The electrodeposition of Zn and Cu-Zn alloy has been investigated in choline chloride (ChCl)/urea (1:2 molar ratio) based deep eutectic solvent (DES). Cyclic voltammetry study demonstrates that the reduction of Zn(II) to Zn is a diffusion-controlled quasi-reversible, one-step, two electrons transfer process. Chronoamperometric investigation indicates that the electrodeposition of Zn on a Cu electrode typically involves three-dimensional instantaneous nucleation with diffusion-controlled growth process. Micro/nanostructured Zn films can be obtained by controlling the electrodeposition potential and temperature. The electrodeposited Zn crystals preferentially orient parallel to the (101) plane. The Zn films electrodeposited under more positive potentials and low temperatures exhibit improved corrosion resistance in 3 wt% NaCl solution. In addition, Cu-Zn alloy films have also been electrodeposited directly from CuO-ZnO precursors in ChCl/urea-based DES. The XRD analysis indicates that the phase composition of the electrodeposited Cu-Zn alloy depends on the electrodeposition potential.

Validation of a mixture-averaged thermal diffusion model for premixed lean hydrogen flames

NASA Astrophysics Data System (ADS)

Schlup, Jason; Blanquart, Guillaume

2018-03-01

The mixture-averaged thermal diffusion model originally proposed by Chapman and Cowling is validated using multiple flame configurations. Simulations using detailed hydrogen chemistry are done on one-, two-, and three-dimensional flames. The analysis spans flat and stretched, steady and unsteady, and laminar and turbulent flames. Quantitative and qualitative results using the thermal diffusion model compare very well with the more complex multicomponent diffusion model. Comparisons are made using flame speeds, surface areas, species profiles, and chemical source terms. Once validated, this model is applied to three-dimensional laminar and turbulent flames. For these cases, thermal diffusion causes an increase in the propagation speed of the flames as well as increased product chemical source terms in regions of high positive curvature. The results illustrate the necessity for including thermal diffusion, and the accuracy and computational efficiency of the mixture-averaged thermal diffusion model.

Three-dimensional hologram display system

NASA Technical Reports Server (NTRS)

Mintz, Frederick (Inventor); Chao, Tien-Hsin (Inventor); Bryant, Nevin (Inventor); Tsou, Peter (Inventor)

2009-01-01

The present invention relates to a three-dimensional (3D) hologram display system. The 3D hologram display system includes a projector device for projecting an image upon a display medium to form a 3D hologram. The 3D hologram is formed such that a viewer can view the holographic image from multiple angles up to 360 degrees. Multiple display media are described, namely a spinning diffusive screen, a circular diffuser screen, and an aerogel. The spinning diffusive screen utilizes spatial light modulators to control the image such that the 3D image is displayed on the rotating screen in a time-multiplexing manner. The circular diffuser screen includes multiple, simultaneously-operated projectors to project the image onto the circular diffuser screen from a plurality of locations, thereby forming the 3D image. The aerogel can use the projection device described as applicable to either the spinning diffusive screen or the circular diffuser screen.

[Three-dimensional parallel collagen scaffold promotes tendon extracellular matrix formation].

PubMed

Zheng, Zefeng; Shen, Weiliang; Le, Huihui; Dai, Xuesong; Ouyang, Hongwei; Chen, Weishan

2016-03-01

To investigate the effects of three-dimensional parallel collagen scaffold on the cell shape, arrangement and extracellular matrix formation of tendon stem cells. Parallel collagen scaffold was fabricated by unidirectional freezing technique, while random collagen scaffold was fabricated by freeze-drying technique. The effects of two scaffolds on cell shape and extracellular matrix formation were investigated in vitro by seeding tendon stem/progenitor cells and in vivo by ectopic implantation. Parallel and random collagen scaffolds were produced successfully. Parallel collagen scaffold was more akin to tendon than random collagen scaffold. Tendon stem/progenitor cells were spindle-shaped and unified orientated in parallel collagen scaffold, while cells on random collagen scaffold had disorder orientation. Two weeks after ectopic implantation, cells had nearly the same orientation with the collagen substance. In parallel collagen scaffold, cells had parallel arrangement, and more spindly cells were observed. By contrast, cells in random collagen scaffold were disorder. Parallel collagen scaffold can induce cells to be in spindly and parallel arrangement, and promote parallel extracellular matrix formation; while random collagen scaffold can induce cells in random arrangement. The results indicate that parallel collagen scaffold is an ideal structure to promote tendon repairing.

Structured light optical microscopy for three-dimensional reconstruction of technical surfaces

NASA Astrophysics Data System (ADS)

Kettel, Johannes; Reinecke, Holger; Müller, Claas

2016-04-01

In microsystems technology quality control of micro structured surfaces with different surface properties is playing an ever more important role. The process of quality control incorporates three-dimensional (3D) reconstruction of specularand diffusive reflecting technical surfaces. Due to the demand on high measurement accuracy and data acquisition rates, structured light optical microscopy has become a valuable solution to solve this problem providing high vertical and lateral resolution. However, 3D reconstruction of specular reflecting technical surfaces still remains a challenge to optical measurement principles. In this paper we present a measurement principle based on structured light optical microscopy which enables 3D reconstruction of specular- and diffusive reflecting technical surfaces. It is realized using two light paths of a stereo microscope equipped with different magnification levels. The right optical path of the stereo microscope is used to project structured light onto the object surface. The left optical path is used to capture the structured illuminated object surface with a camera. Structured light patterns are generated by a Digital Light Processing (DLP) device in combination with a high power Light Emitting Diode (LED). Structured light patterns are realized as a matrix of discrete light spots to illuminate defined areas on the object surface. The introduced measurement principle is based on multiple and parallel processed point measurements. Analysis of the measured Point Spread Function (PSF) by pattern recognition and model fitting algorithms enables the precise calculation of 3D coordinates. Using exemplary technical surfaces we demonstrate the successful application of our measurement principle.

Seismicity of the Earth 1900-2010 Aleutian arc and vicinity

USGS Publications Warehouse

Benz, Harley M.; Herman, Matthew; Tarr, Arthur C.; Hayes, Gavin P.; Furlong, Kevin P.; Villaseñor, Antonio; Dart, Richard L.; Rhea, Susan

2011-01-01

This map shows details of the Aleutian arc not visible in an earlier publication. The Aleutian arc extends about 3,000 km from the Gulf of Alaska to the Kamchatka Peninsula. It marks the region where the Pacific plate subducts into the mantle beneath the North America plate. This subduction is responsible for the generation of the Aleutian Islands and the deep offshore Aleutian Trench. Relative to a fixed North America plate, the Pacific plate is moving northwest at a rate that increases from about 55 mm per year at the arc's eastern edge to 75 mm per year near its western terminus. In the east, the convergence of the plates is nearly perpendicular to the plate boundary. However, because of the boundary's curvature, as one travels westward along the arc, the subduction becomes more and more oblique to the boundary until the relative plate motion becomes parallel to the arc at the Near Islands near its western edge. Subduction zones such as the Aleutian arc are geologically complex and produce numerous earthquakes from multiple sources. Deformation of the overriding North America plate generates shallow crustal earthquakes, whereas slip at the interface of the plates generates interplate earthquakes that extend from near the base of the trench to depths of 40 to 60 km. At greater depths, Aleutian arc earthquakes occur within the subducting Pacific plate and can reach depths of 300 km. Since 1900, six great earthquakes have occurred along the Aleutian Trench, Alaska Peninsula, and Gulf of Alaska: M8.4 1906 Rat Islands; M8.6 1938 Shumagin Islands; M8.6 1946 Unimak Island; M8.6 1957 Andreanof Islands; M9.2 1964 Prince William Sound; and M8.7 1965 Rat Islands. Several relevant tectonic elements (plate boundaries and active volcanoes) provide a context for the seismicity presented on the main map panel. The plate boundaries are most accurate along the axis of the Aleutian Trench and more diffuse or speculative in extreme northeastern Russia. The active volcanoes parallel the Aleutian Trench from the Gulf of Alaska to the Rat Islands.

The parallel-antiparallel signal difference in double-wave-vector diffusion-weighted MR at short mixing times: A phase evolution perspective

NASA Astrophysics Data System (ADS)

Finsterbusch, Jürgen

2011-01-01

Experiments with two diffusion weightings applied in direct succession in a single acquisition, so-called double- or two-wave-vector diffusion-weighting (DWV) experiments at short mixing times, have been shown to be a promising tool to estimate cell or compartment sizes, e.g. in living tissue. The basic theory for such experiments predicts that the signal decays for parallel and antiparallel wave vector orientations differ by a factor of three for small wave vectors. This seems to be surprising because in standard, single-wave-vector experiments the polarity of the diffusion weighting has no influence on the signal attenuation. Thus, the question how this difference can be understood more pictorially is often raised. In this rather educational manuscript, the phase evolution during a DWV experiment for simple geometries, e.g. diffusion between parallel, impermeable planes oriented perpendicular to the wave vectors, is considered step-by-step and demonstrates how the signal difference develops. Considering the populations of the phase distributions obtained, the factor of three between the signal decays which is predicted by the theory can be reproduced. Furthermore, the intermediate signal decay for orthogonal wave vector orientations can be derived when investigating diffusion in a box. Thus, the presented “phase gymnastics” approach may help to understand the signal modulation observed in DWV experiments at short mixing times.

Knudsen pump inspired by Crookes radiometer with a specular wall

NASA Astrophysics Data System (ADS)

Baier, Tobias; Hardt, Steffen; Shahabi, Vahid; Roohi, Ehsan

2017-03-01

A rarefied gas is considered in a channel consisting of two infinite parallel plates between which an evenly spaced array of smaller plates is arranged normal to the channel direction. Each of these smaller plates is assumed to possess one ideally specularly reflective and one ideally diffusively reflective side. When the temperature of the small plates differs from the temperature of the sidewalls of the channel, these boundary conditions result in a temperature profile around the edges of each small plate that breaks the reflection symmetry along the channel direction. This in turn results in a force on each plate and a net gas flow along the channel. The situation is analyzed numerically using the direct simulation Monte Carlo method and compared with analytical results where available. The influence of the ideally specularly reflective wall is assessed by comparing with simulations using a finite accommodation coefficient at the corresponding wall. The configuration bears some similarity to a Crookes radiometer, where a nonsymmetric temperature profile at the radiometer vanes is generated by different temperatures on each side of the vane, resulting in a motion of the rotor. The described principle may find applications in pumping gas on small scales driven by temperature gradients.

Three-dimensional elastic-plastic finite-element analyses of constraint variations in cracked bodies

NASA Technical Reports Server (NTRS)

Newman, J. C., Jr.; Bigelow, C. A.; Shivakumar, K. N.

1993-01-01

Three-dimensional elastic-plastic (small-strain) finite-element analyses were used to study the stresses, deformations, and constraint variations around a straight-through crack in finite-thickness plates for an elastic-perfectly plastic material under monotonic and cyclic loading. Middle-crack tension specimens were analyzed for thicknesses ranging from 1.25 to 20 mm with various crack lengths. Three local constraint parameters, related to the normal, tangential, and hydrostatic stresses, showed similar variations along the crack front for a given thickness and applied stress level. Numerical analyses indicated that cyclic stress history and crack growth reduced the local constraint parameters in the interior of a plate, especially at high applied stress levels. A global constraint factor alpha(sub g) was defined to simulate three-dimensional effects in two-dimensional crack analyses. The global constraint factor was calculated as an average through-the-thickness value over the crack-front plastic region. Values of alpha(sub g) were found to be nearly independent of crack length and were related to the stress-intensity factor for a given thickness.

Unsteady Heat and Mass Transfer of Chemically Reacting Micropolar Fluid in a Porous Channel with Hall and Ion Slip Currents

PubMed Central

2014-01-01

This paper presents an incompressible two-dimensional heat and mass transfer of an electrically conducting micropolar fluid flow in a porous medium between two parallel plates with chemical reaction, Hall and ion slip effects. Let there be periodic injection or suction at the lower and upper plates and the nonuniform temperature and concentration at the plates are varying periodically with time. The flow field equations are reduced to nonlinear ordinary differential equations using similarity transformations and then solved numerically by quasilinearization technique. The profiles of velocity components, microrotation, temperature distribution and concentration are studied for different values of fluid and geometric parameters such as Hartmann number, Hall and ion slip parameters, inverse Darcy parameter, Prandtl number, Schmidt number, and chemical reaction rate and shown in the form of graphs. PMID:27419211

Current Plate Motion Across the Southwest Indian Ridge: Implications for the Diffuse Oceanic Plate Boundary Between Nubia and Somalia

NASA Astrophysics Data System (ADS)

Horner-Johnson, B. C.; Cowles, S. M.; Gordon, R. G.; Argus, D. F.

2001-12-01

Prior studies of plate motion data along the Southwest Indian Ridge (SWIR) have produced results that conflict in detail. Chu & Gordon [1999], from an analysis of 59 spreading rates averaged over 3 Myr and of the azimuths of active transform faults, found that the data are most consistent with a diffuse Nubia-Somalia plate boundary where it intersects the SWIR. When they solve for the best-fitting hypothetical narrow boundary, they find that it lies near 37° E, east of the Prince Edward fracture zone. They find a Nubia-Somalia pole of rotation near the east coast of South Africa. In contrast, Lemaux, Gordon, and Royer [2001], from an analysis of 237 crossings of marine magnetic anomaly 5 (11 Ma), find that most of the motion is accommodated in a narrow zone, most likely along the ``inactive'' trace of the Andrew Bain fracture zone complex (ABFZC), which intersects the SWIR near 32° E. They find a pole well to the west of, and probably to the southwest of, the pole of rotation found by Chu & Gordon. Their pole indicates mainly strike-slip motion along the ``inactive'' ABFZC. To resolve these conflicting results, we determined a new greatly expanded and spatially much denser set of 243 spreading rates and analyzed available bathymetric data of active transform faults along the SWIR. The data show that the African oceanic lithosphere spreading away from the SWIR cannot simply be two plates divided by a single narrow boundary. Our interpretation of the data is as follows. Near the SWIR, there is a diffuse boundary with a western limit near the ABFZC and an eastern limit near 63.5° E. Slip is partitioned in this wide boundary. Somewhere near the ABFZC (most likely the ABFZC itself) is a concentrated locus of right-lateral shearing parallel to the ABFZC whereas contraction perpendicular to the ABFZC is accommodated east of the ABFZC, perhaps over a very broad zone.

Analytical and numerical study on cooling flow field designs performance of PEM fuel cell with variable heat flux

NASA Astrophysics Data System (ADS)

Afshari, Ebrahim; Ziaei-Rad, Masoud; Jahantigh, Nabi

2016-06-01

In PEM fuel cells, during electrochemical generation of electricity more than half of the chemical energy of hydrogen is converted to heat. This heat of reactions, if not exhausted properly, would impair the performance and durability of the cell. In general, large scale PEM fuel cells are cooled by liquid water that circulates through coolant flow channels formed in bipolar plates or in dedicated cooling plates. In this paper, a numerical method has been presented to study cooling and temperature distribution of a polymer membrane fuel cell stack. The heat flux on the cooling plate is variable. A three-dimensional model of fluid flow and heat transfer in cooling plates with 15 cm × 15 cm square area is considered and the performances of four different coolant flow field designs, parallel field and serpentine fields are compared in terms of maximum surface temperature, temperature uniformity and pressure drop characteristics. By comparing the results in two cases, the constant and variable heat flux, it is observed that applying constant heat flux instead of variable heat flux which is actually occurring in the fuel cells is not an accurate assumption. The numerical results indicated that the straight flow field model has temperature uniformity index and almost the same temperature difference with the serpentine models, while its pressure drop is less than all of the serpentine models. Another important advantage of this model is the much easier design and building than the spiral models.

Two-dimensional photon-counting detector arrays based on microchannel array plates

NASA Technical Reports Server (NTRS)

Timothy, J. G.; Bybee, R. L.

1975-01-01

The production of simple and rugged photon-counting detector arrays has been made possible by recent improvements in the performance of the microchannel array plate (MCP) and by the parallel development of compatible electronic readout systems. The construction of proximity-focused MCP arrays of novel design in which photometric information from (n x m) picture elements is read out with a total of (n + m) amplifier and discriminator circuits is described. Results obtained with a breadboard (32 x 32)-element array employing 64 charge-sensitive amplifiers are presented, and the application of systems of this type in spectrometers and cameras for use with ground-based telescopes and on orbiting spacecraft discussed.

Stability of a viscous fluid in a rectangular cavity in the presence of a magnetic field

NASA Technical Reports Server (NTRS)

Liang, C. Y.; Hung, Y. Y.

1976-01-01

The stability of an electrically conducting fluid subjected to two dimensional disturbance was investigated. A physical system consisting of two parallel infinite vertical plates which are thermally insulated was studied. An external magnetic field of constant strength was applied to normal plates. The fluid was heated from below so that a steady temperature gradient was maintained in the fluid. The governing equations were derived by perturbation technique, and solutions were obtained by a modified Galerkin method. It was found that the presence of the magnetic field increases the stability of the physical system and instability can occur in the form of neutral or oscillatory instability.

Modified equations of finite-size layered plates made of orthotropic material. Comparison of the results of numerical calculations with analytical solutions

NASA Astrophysics Data System (ADS)

Volchkov, Yu. M.

2017-09-01

This paper describes the modified bending equations of layered orthotropic plates in the first approximation. The approximation of the solution of the equation of the three-dimensional theory of elasticity by the Legendre polynomial segments is used to obtain differential equations of the elastic layer. For the approximation of equilibrium equations and boundary conditions of three-dimensional theory of elasticity, several approximations of each desired function (stresses and displacements) are used. The stresses at the internal points of the plate are determined from the defining equations for the orthotropic material, averaged with respect to the plate thickness. The construction of the bending equations of layered plates for each layer is carried out with the help of the elastic layer equations and the conjugation conditions on the boundaries between layers, which are conditions for the continuity of normal stresses and displacements. The numerical solution of the problem of bending of the rectangular layered plate obtained with the help of modified equations is compared with an analytical solution. It is determined that the maximum error in determining the stresses does not exceed 3 %.

The Japan Trench and its juncture with the Kuril Trench: cruise results of the Kaiko project, Leg 3

USGS Publications Warehouse

Cadet, J.-P.; Kobayashi, K.; Aubouin, J.; Boulegue, J.; Deplus, C.; Dubois, J.; von Huene, Roland E.; Jolivet, L.; Kanazawa, T.; Kasahara, J.; Koizumi, K.; Lallemand, S.; Nakamura, Y.; Pautot, G.; Suyehiro, K.; Tani, S.; Tokuyama, H.; Yamazaki, T.

1987-01-01

This paper presents the results of a detailed survey combining Seabeam mapping, gravity and geomagnetic measurements as well as single-channel seismic reflection observations in the Japan Trench and the juncture with the Kuril Trench during the French-Japanese Kaiko project (northern sector of the Leg 3) on the R/V "Jean Charcot". The main data acquired during the cruise, such as the Seabeam maps, magnetic anomalies pattern, and preliminary interpretations are discussed. These new data cover an area of 18,000 km2 and provide for the first time a detailed three-dimensional image of the Japan Trench. Combined with the previous results, the data indicate new structural interpretations. A comparative study of Seabeam morphology, single-channel and reprocessed multichannel records lead to the conclusion that along the northern Japan Trench there is little evidence of accretion but, instead, a tectonic erosion of the overriding plate. The tectonic pattern on the oceanic side of the trench is controlled by the creation of new normal faults parallel to the Japan Trench axis, which is a direct consequence of the downward flexure of the Pacific plate. In addition to these new faults, ancient normal faults trending parallel to the N65?? oceanic magnetic anomalies and oblique to the Japan trench axis are reactivated, so that two directions of normal faulting are observed seaward of the Japan Trench. Only one direction of faulting is observed seaward of the Kuril Trench because of the parallelism between the trench axis and the magnetic anomalies. The convergent front of the Kuril Trench is offset left-laterally by 20 km relative to those of the Japan Trench. This transform fault and the lower slope of the southernmost Kuril Trench are represented by very steep scarps more than 2 km high. Slightly south of the juncture, the Erimo Seamount riding on the Pacific plate, is now entering the subduction zone. It has been preceded by at least another seamount as revealed by magnetic anomalies across the landward slope of the trench. Deeper future studies will be necessary to discriminate between the two following hypothesis about the origin of the curvature between both trenches: Is it due to the collision of an already subducted chain of seamounts? or does it correspond to one of the failure lines of the America/Eurasia plate boundary? ?? 1987.

Computation of three-dimensional shock wave and boundary-layer interactions

NASA Technical Reports Server (NTRS)

Hung, C. M.

1985-01-01

Computations of the impingement of an oblique shock wave on a cylinder and a supersonic flow past a blunt fin mounted on a plate are used to study three dimensional shock wave and boundary layer interaction. In the impingement case, the problem of imposing a planar impinging shock as an outer boundary condition is discussed and the details of particle traces in windward and leeward symmetry planes and near the body surface are presented. In the blunt fin case, differences between two dimensional and three dimensional separation are discussed, and the existence of an unique high speed, low pressure region under the separated spiral vortex core is demonstrated. The accessibility of three dimensional separation is discussed.

Diffusion, Absorbing States, and Nonequilibrium Phase Transitions in Range Expansions and Evolution

NASA Astrophysics Data System (ADS)

Lavrentovich, Maxim Olegovich

The spatial organization of a population plays a key role in its evolutionary dynamics and growth. In this thesis, we study the dynamics of range expansions, in which populations expand into new territory. Focussing on microbes, we first consider how nutrients diffuse and are absorbed in a population, allowing it to grow. These nutrients may be absorbed before reaching the population interior, and this "nutrient shielding'' can confine the growth to a thin region on the population periphery. A thin population front implies a small local effective population size and enhanced number fluctuations (or genetic drift). We then study evolutionary dynamics under these growth conditions. In particular, we calculate the survival probability of mutations with a selective advantage occurring at the population front for two-dimensional expansions (e.g., along the surface of an agar plate), and three-dimensional expansions (e.g., an avascular tumor). We also consider the effects of irreversible, deleterious mutations which can lead to the loss of the advantageous mutation in the population via a "mutational meltdown,'' or non-equilibrium phase transition. We examine the effects of an inflating population frontier on the phase transition. Finally, we discuss how spatial dimension and frontier roughness influence range expansions of mutualistic, cross-feeding variants. We find here universal features of the phase diagram describing the onset of a mutualistic phase in which the variants remain mixed at long times.

Strongly nonlinear dynamics of electrolytes in large ac voltages.

PubMed

Højgaard Olesen, Laurits; Bazant, Martin Z; Bruus, Henrik

2010-07-01

We study the response of a model microelectrochemical cell to a large ac voltage of frequency comparable to the inverse cell relaxation time. To bring out the basic physics, we consider the simplest possible model of a symmetric binary electrolyte confined between parallel-plate blocking electrodes, ignoring any transverse instability or fluid flow. We analyze the resulting one-dimensional problem by matched asymptotic expansions in the limit of thin double layers and extend previous work into the strongly nonlinear regime, which is characterized by two features--significant salt depletion in the electrolyte near the electrodes and, at very large voltage, the breakdown of the quasiequilibrium structure of the double layers. The former leads to the prediction of "ac capacitive desalination" since there is a time-averaged transfer of salt from the bulk to the double layers, via oscillating diffusion layers. The latter is associated with transient diffusion limitation, which drives the formation and collapse of space-charge layers, even in the absence of any net Faradaic current through the cell. We also predict that steric effects of finite ion sizes (going beyond dilute-solution theory) act to suppress the strongly nonlinear regime in the limit of concentrated electrolytes, ionic liquids, and molten salts. Beyond the model problem, our reduced equations for thin double layers, based on uniformly valid matched asymptotic expansions, provide a useful mathematical framework to describe additional nonlinear responses to large ac voltages, such as Faradaic reactions, electro-osmotic instabilities, and induced-charge electrokinetic phenomena.

Finite element analysis of three patterns of internal fixation of fractures of the mandibular condyle.

PubMed

Aquilina, Peter; Chamoli, Uphar; Parr, William C H; Clausen, Philip D; Wroe, Stephen

2013-06-01

The most stable pattern of internal fixation for fractures of the mandibular condyle is a matter for ongoing discussion. In this study we investigated the stability of three commonly used patterns of plate fixation, and constructed finite element models of a simulated mandibular condylar fracture. The completed models were heterogeneous in the distribution of bony material properties, contained about 1.2 million elements, and incorporated simulated jaw-adducting musculature. Models were run assuming linear elasticity and isotropic material properties for bone. This model was considerably larger and more complex than previous finite element models that have been used to analyse the biomechanical behaviour of differing plating techniques. The use of two parallel 2.0 titanium miniplates gave a more stable configuration with lower mean element stresses and displacements over the use of a single miniplate. In addition, a parallel orientation of two miniplates resulted in lower stresses and displacements than did the use of two miniplates in an offset pattern. The use of two parallel titanium plates resulted in a superior biomechanical result as defined by mean element stresses and relative movement between the fractured fragments in these finite element models. Copyright © 2012 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Effects of mass transfer on MHD three dimensional flow of a Prandtl liquid over a flat plate in the presence of chemical reaction

NASA Astrophysics Data System (ADS)

Ganesh Kumar, K.; Rizwan-ul-Haq; Rudraswamy, N. G.; Gireesha, B. J.

The present study addresses the three-dimensional flow of a Prandtl fluid over a Riga plate in the presence of chemical reaction and convective condition. The converted set of boundary layer equations are solved numerically by RKF four-fifth method. Obtained numerical results for flow and mass transfer characteristics are discussed for various physical parameters. Additionally, the skin friction coefficient and Sherwood number are also presented. It is found that, the momentum boundary layer thickness is dominant for higher values of α and solutal boundary layer is low for higher Schmidt number and chemical reaction parameter.

Stratified Shear Flows In Pipe Geometries

NASA Astrophysics Data System (ADS)

Harabin, George; Camassa, Roberto; McLaughlin, Richard; UNC Joint Fluids Lab Team Team

2015-11-01

Exact and series solutions to the full Navier-Stokes equations coupled to the advection diffusion equation are investigated in tilted three-dimensional pipe geometries. Analytic techniques for studying the three-dimensional problem provide a means for tackling interesting questions such as the optimal domain for mass transport, and provide new avenues for experimental investigation of diffusion driven flows. Both static and time dependent solutions will be discussed. NSF RTG DMS-0943851, NSF RTG ARC-1025523, NSF DMS-1009750.

78 FR 50378 - Diffusion-Annealed, Nickel-Plated Flat-Rolled Steel Products From Japan: Postponement of...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-19

...-Plated Flat-Rolled Steel Products From Japan: Postponement of Preliminary Determination of Antidumping... investigation of diffusion-annealed, nickel-plated flat-rolled steel products from Japan. See Diffusion- Annealed, Nickel-Plated Flat-Rolled Steel Products From Japan: Initiation of Antidumping Duty Investigation...

Parallel Simulation of Three-Dimensional Free Surface Fluid Flow Problems

DOE Office of Scientific and Technical Information (OSTI.GOV)

BAER,THOMAS A.; SACKINGER,PHILIP A.; SUBIA,SAMUEL R.

1999-10-14

Simulation of viscous three-dimensional fluid flow typically involves a large number of unknowns. When free surfaces are included, the number of unknowns increases dramatically. Consequently, this class of problem is an obvious application of parallel high performance computing. We describe parallel computation of viscous, incompressible, free surface, Newtonian fluid flow problems that include dynamic contact fines. The Galerkin finite element method was used to discretize the fully-coupled governing conservation equations and a ''pseudo-solid'' mesh mapping approach was used to determine the shape of the free surface. In this approach, the finite element mesh is allowed to deform to satisfy quasi-staticmore » solid mechanics equations subject to geometric or kinematic constraints on the boundaries. As a result, nodal displacements must be included in the set of unknowns. Other issues discussed are the proper constraints appearing along the dynamic contact line in three dimensions. Issues affecting efficient parallel simulations include problem decomposition to equally distribute computational work among a SPMD computer and determination of robust, scalable preconditioners for the distributed matrix systems that must be solved. Solution continuation strategies important for serial simulations have an enhanced relevance in a parallel coquting environment due to the difficulty of solving large scale systems. Parallel computations will be demonstrated on an example taken from the coating flow industry: flow in the vicinity of a slot coater edge. This is a three dimensional free surface problem possessing a contact line that advances at the web speed in one region but transitions to static behavior in another region. As such, a significant fraction of the computational time is devoted to processing boundary data. Discussion focuses on parallel speed ups for fixed problem size, a class of problems of immediate practical importance.« less

Microrheology: Structural evolution under static and dynamic conditions by simultaneous analysis of confocal microscopy and diffusing wave spectroscopy

NASA Astrophysics Data System (ADS)

Nicolas, Yves; Paques, Marcel; Knaebel, Alexandra; Steyer, Alain; Munch, Jean-Pierre; Blijdenstein, Theo B. J.; van Aken, George A.

2003-08-01

An oscillatory shear configuration was developed to improve understanding of structural evolution during deformation. It combines an inverted confocal scanning laser microscope (CSLM) and a special sample holder that can apply to the sample specific deformation: oscillatory shear or steady strain. In this configuration, a zero-velocity plane is created in the sample by moving two plates in opposite directions, thereby providing stable observation conditions of the structural behavior under deformation. The configuration also includes diffusion wave spectroscopy (DWS) to monitor the network properties via particle mobility under static and dynamic conditions. CSLM and DWS can be performed simultaneously and three-dimensional images can be obtained under static conditions. This configuration is mainly used to study mechanistic phenomena like particle interaction, aggregation, gelation and network disintegration, interactions at interfaces under static and dynamic conditions in semisolid food materials (desserts, dressings, sauces, dairy products) and in nonfood materials (mineral emulsions, etc.). Preliminary data obtained with this new oscillatory shear configuration are described that demonstrate their capabilities and the potential contribution to other areas of application also.

Roles of Diffusion Dynamics in Stem Cell Signaling and Three-Dimensional Tissue Development.

PubMed

McMurtrey, Richard J

2017-09-15

Recent advancements in the ability to construct three-dimensional (3D) tissues and organoids from stem cells and biomaterials have not only opened abundant new research avenues in disease modeling and regenerative medicine but also have ignited investigation into important aspects of molecular diffusion in 3D cellular architectures. This article describes fundamental mechanics of diffusion with equations for modeling these dynamic processes under a variety of scenarios in 3D cellular tissue constructs. The effects of these diffusion processes and resultant concentration gradients are described in the context of the major molecular signaling pathways in stem cells that both mediate and are influenced by gas and nutrient concentrations, including how diffusion phenomena can affect stem cell state, cell differentiation, and metabolic states of the cell. The application of these diffusion models and pathways is of vital importance for future studies of developmental processes, disease modeling, and tissue regeneration.

Statistical analysis of vibration in tyres

NASA Astrophysics Data System (ADS)

Le Bot, Alain; Bazari, Zakia; Klein, Philippe; Lelong, Joël

2017-03-01

The vibration in tyres submitted to random forces in the contact zone is investigated with the model of prestressed orthotropic plate on visco-elastic foundation. It is shown that beyond a cut-on frequency a single wave propagates whose speed is directional-dependent. A systematic numerical exploration of the governing equation solutions shows that three regimes may exist in such plates. These are modal field, diffuse field and free field. For actual tyres which present a high level of damping, the passage from low to high frequencies generally explores the modal and free field regimes but not the diffuse field regime.

A geometrical multi-scale numerical method for coupled hygro-thermo-mechanical problems in photovoltaic laminates.

PubMed

Lenarda, P; Paggi, M

A comprehensive computational framework based on the finite element method for the simulation of coupled hygro-thermo-mechanical problems in photovoltaic laminates is herein proposed. While the thermo-mechanical problem takes place in the three-dimensional space of the laminate, moisture diffusion occurs in a two-dimensional domain represented by the polymeric layers and by the vertical channel cracks in the solar cells. Therefore, a geometrical multi-scale solution strategy is pursued by solving the partial differential equations governing heat transfer and thermo-elasticity in the three-dimensional space, and the partial differential equation for moisture diffusion in the two dimensional domains. By exploiting a staggered scheme, the thermo-mechanical problem is solved first via a fully implicit solution scheme in space and time, with a specific treatment of the polymeric layers as zero-thickness interfaces whose constitutive response is governed by a novel thermo-visco-elastic cohesive zone model based on fractional calculus. Temperature and relative displacements along the domains where moisture diffusion takes place are then projected to the finite element model of diffusion, coupled with the thermo-mechanical problem by the temperature and crack opening dependent diffusion coefficient. The application of the proposed method to photovoltaic modules pinpoints two important physical aspects: (i) moisture diffusion in humidity freeze tests with a temperature dependent diffusivity is a much slower process than in the case of a constant diffusion coefficient; (ii) channel cracks through Silicon solar cells significantly enhance moisture diffusion and electric degradation, as confirmed by experimental tests.

Electrostatically confined nanoparticle interactions and dynamics.

PubMed

Eichmann, Shannon L; Anekal, Samartha G; Bevan, Michael A

2008-02-05

We report integrated evanescent wave and video microscopy measurements of three-dimensional trajectories of 50, 100, and 250 nm gold nanoparticles electrostatically confined between parallel planar glass surfaces separated by 350 and 600 nm silica colloid spacers. Equilibrium analyses of single and ensemble particle height distributions normal to the confining walls produce net electrostatic potentials in excellent agreement with theoretical predictions. Dynamic analyses indicate lateral particle diffusion coefficients approximately 30-50% smaller than expected from predictions including the effects of the equilibrium particle distribution within the gap and multibody hydrodynamic interactions with the confining walls. Consistent analyses of equilibrium and dynamic information in each measurement do not indicate any roles for particle heating or hydrodynamic slip at the particle or wall surfaces, which would both increase diffusivities. Instead, lower than expected diffusivities are speculated to arise from electroviscous effects enhanced by the relative extent (kappaa approximately 1-3) and overlap (kappah approximately 2-4) of electrostatic double layers on the particle and wall surfaces. These results demonstrate direct, quantitative measurements and a consistent interpretation of metal nanoparticle electrostatic interactions and dynamics in a confined geometry, which provides a basis for future similar measurements involving other colloidal forces and specific biomolecular interactions.

Evaporative cooling of air in an adiabatic channel with partially wetted zones

NASA Astrophysics Data System (ADS)

Terekhov, V. I.; Gorbachev, M. V.; Khafaji, H. Q.

2016-03-01

The paper deals with the numerical study of heat and mass transfer in the process of direct evaporation air cooling in the laminar flow of forced convection in a channel between two parallel insulated plates with alternating wet and dry zones along the length. The system of Navier-Stokes equations and equations of energy and steam diffusion are being solved in two-dimensional approximation. At the channel inlet, all thermal gas-dynamic parameters are constant over the cross section, and the channel walls are adiabatic. The studies were carried out with varying number of dry zones ( n = 0-16), their relative length ( s/l = 0-1) and Reynolds number Re = 50-1000 in the flow of dry air (φ0 = 0) with a constant temperature at the inlet (T 0 = 30 °C). The main attention is paid to optimization analysis of evaporation cell characteristics. It is shown that an increase in the number of alternating steps leads to an increase in the parameters of thermal and humid efficiency. With an increase in Re number and a decrease in the extent of wet areas, the efficiency parameter reduces.

Source Term Model for Steady Micro Jets in a Navier-Stokes Computer Code

NASA Technical Reports Server (NTRS)

Waithe, Kenrick A.

2005-01-01

A source term model for steady micro jets was implemented into a non-proprietary Navier-Stokes computer code, OVERFLOW. The source term models the mass flow and momentum created by a steady blowing micro jet. The model is obtained by adding the momentum and mass flow created by the jet to the Navier-Stokes equations. The model was tested by comparing with data from numerical simulations of a single, steady micro jet on a flat plate in two and three dimensions. The source term model predicted the velocity distribution well compared to the two-dimensional plate using a steady mass flow boundary condition, which was used to simulate a steady micro jet. The model was also compared to two three-dimensional flat plate cases using a steady mass flow boundary condition to simulate a steady micro jet. The three-dimensional comparison included a case with a grid generated to capture the circular shape of the jet and a case without a grid generated for the micro jet. The case without the jet grid mimics the application of the source term. The source term model compared well with both of the three-dimensional cases. Comparisons of velocity distribution were made before and after the jet and Mach and vorticity contours were examined. The source term model allows a researcher to quickly investigate different locations of individual or several steady micro jets. The researcher is able to conduct a preliminary investigation with minimal grid generation and computational time.

A comparison between orthogonal and parallel plating methods for distal humerus fractures: a prospective randomized trial.

PubMed

Lee, Sang Ki; Kim, Kap Jung; Park, Kyung Hoon; Choy, Won Sik

2014-10-01

With the continuing improvements in implants for distal humerus fractures, it is expected that newer types of plates, which are anatomically precontoured, thinner and less irritating to soft tissue, would have comparable outcomes when used in a clinical study. The purpose of this study was to compare the clinical and radiographic outcomes in patients with distal humerus fractures who were treated with orthogonal and parallel plating methods using precontoured distal humerus plates. Sixty-seven patients with a mean age of 55.4 years (range 22-90 years) were included in this prospective study. The subjects were randomly assigned to receive 1 of 2 treatments: orthogonal or parallel plating. The following results were assessed: operating time, time to fracture union, presence of a step or gap at the articular margin, varus-valgus angulation, functional recovery, and complications. No intergroup differences were observed based on radiological and clinical results between the groups. In our practice, no significant differences were found between the orthogonal and parallel plating methods in terms of clinical outcomes, mean operation time, union time, or complication rates. There were no cases of fracture nonunion in either group; heterotrophic ossification was found 3 patients in orthogonal plating group and 2 patients in parallel plating group. In our practice, no significant differences were found between the orthogonal and parallel plating methods in terms of clinical outcomes or complication rates. However, orthogonal plating method may be preferred in cases of coronal shear fractures, where posterior to anterior fixation may provide additional stability to the intraarticular fractures. Additionally, parallel plating method may be the preferred technique used for fractures that occur at the most distal end of the humerus.

Effects of calcium leaching on diffusion properties of hardened and altered cement pastes

NASA Astrophysics Data System (ADS)

Kurumisawa, Kiyofumi; Haga, Kazuko; Hayashi, Daisuke; Owada, Hitoshi

2017-06-01

It is very important to predict alterations in the concrete used for fabricating disposal containers for radioactive waste. Therefore, it is necessary to understand the alteration of cementitious materials caused by calcium leaching when they are in contact with ground water in the long term. To evaluate the long-term transport characteristics of cementitious materials, the microstructural behavior of these materials should be considered. However, many predictive models of transport characteristics focus on the pore structure, while only few such models consider both, the spatial distribution of calcium silicate hydrate (C-S-H), portlandite, and the pore spaces. This study focused on the spatial distribution of these cement phases. The auto-correlation function of each phase of cementitious materials was calculated from two-dimensional backscattered electron imaging, and the three-dimensional spatial image of the cementitious material was produced using these auto-correlation functions. An attempt was made to estimate the diffusion coefficient of chloride from the three-dimensional spatial image. The estimated diffusion coefficient of the altered sample from the three-dimensional spatial image was found to be comparable to the measured value. This demonstrated that it is possible to predict the diffusion coefficient of the altered cement paste by using the proposed model.

Biomechanical analysis of titanium fixation plates and screws in sagittal split ramus osteotomies.

PubMed

Atik, F; Atac, M S; Özkan, A; Kılınc, Y; Arslan, M

2016-01-01

The aim of the study was to evaluate the mechanical behavior of three different fixation methods used in the bilateral sagittal split ramus osteotomy. Three different three-dimensional finite element models were created, each corresponding to three different fixation methods. The mandibles were fixed with double straight 4-hole, square 4-hole, and 5-hole Y plates. 150 N incisal occlusal loads were simulated on the distal segments. ANSYS software ((v 10; ANSYS Inc., Canonsburg, PA) was used to calculate the Von Mises stresses on fixative appliances. The highest Von Mises stress values were found in Y plate. The lowest values were isolated in double straight plate group. It was concluded that the use of double 4-hole straight plates provided the sufficient stability on the osteotomy site when compared with the other rigid fixation methods used in this study.

Functional Parallel Factor Analysis for Functions of One- and Two-dimensional Arguments.

PubMed

Choi, Ji Yeh; Hwang, Heungsun; Timmerman, Marieke E

2018-03-01

Parallel factor analysis (PARAFAC) is a useful multivariate method for decomposing three-way data that consist of three different types of entities simultaneously. This method estimates trilinear components, each of which is a low-dimensional representation of a set of entities, often called a mode, to explain the maximum variance of the data. Functional PARAFAC permits the entities in different modes to be smooth functions or curves, varying over a continuum, rather than a collection of unconnected responses. The existing functional PARAFAC methods handle functions of a one-dimensional argument (e.g., time) only. In this paper, we propose a new extension of functional PARAFAC for handling three-way data whose responses are sequenced along both a two-dimensional domain (e.g., a plane with x- and y-axis coordinates) and a one-dimensional argument. Technically, the proposed method combines PARAFAC with basis function expansion approximations, using a set of piecewise quadratic finite element basis functions for estimating two-dimensional smooth functions and a set of one-dimensional basis functions for estimating one-dimensional smooth functions. In a simulation study, the proposed method appeared to outperform the conventional PARAFAC. We apply the method to EEG data to demonstrate its empirical usefulness.

Partial Arc Curvilinear Direct Drive Servomotor

NASA Technical Reports Server (NTRS)

Sun, Xiuhong (Inventor)

2014-01-01

A partial arc servomotor assembly having a curvilinear U-channel with two parallel rare earth permanent magnet plates facing each other and a pivoted ironless three phase coil armature winding moves between the plates. An encoder read head is fixed to a mounting plate above the coil armature winding and a curvilinear encoder scale is curved to be co-axis with the curvilinear U-channel permanent magnet track formed by the permanent magnet plates. Driven by a set of miniaturized power electronics devices closely looped with a positioning feedback encoder, the angular position and velocity of the pivoted payload is programmable and precisely controlled.

Modeling the poroelastic response to megathrust earthquakes: A look at the 2012 Mw 7.6 Costa Rican event

NASA Astrophysics Data System (ADS)

McCormack, Kimberly A.; Hesse, Marc A.

2018-04-01

We model the subsurface hydrologic response to the 7.6 Mw subduction zone earthquake that occurred on the plate interface beneath the Nicoya peninsula in Costa Rica on September 5, 2012. The regional-scale poroelastic model of the overlying plate integrates seismologic, geodetic and hydrologic data sets to predict the post-seismic poroelastic response. A representative two-dimensional model shows that thrust earthquakes with a slip width less than a third of their depth produce complex multi-lobed pressure perturbations in the shallow subsurface. This leads to multiple poroelastic relaxation timescales that may overlap with the longer viscoelastic timescales. In the three-dimensional model, the complex slip distribution of 2012 Nicoya event and its small width to depth ratio lead to a pore pressure distribution comprising multiple trench parallel ridges of high and low pressure. This leads to complex groundwater flow patterns, non-monotonic variations in predicted well water levels, and poroelastic relaxation on multiple time scales. The model also predicts significant tectonically driven submarine groundwater discharge off-shore. In the weeks following the earthquake, the predicted net submarine groundwater discharge in the study area increases, creating a 100 fold increase in net discharge relative to topography-driven flow over the first 30 days. Our model suggests the hydrological response on land is more complex than typically acknowledged in tectonic studies. This may complicate the interpretation of transient post-seismic surface deformations. Combined tectonic-hydrological observation networks have the potential to reduce such ambiguities.

Plate kinematics of the Afro-Arabian Rift System with emphasis on the Afar Depression, Ethiopia

NASA Astrophysics Data System (ADS)

Bottenberg, Helen Carrie

This work utilizes the Four-Dimensional Plates (4DPlates) software, and Differential Interferometric Synthetic Aperture Radar (DInSAR) to examine plate-scale, regional-scale and local-scale kinematics of the Afro-Arabian Rift System with emphasis on the Afar Depression in Ethiopia. First, the 4DPlates is used to restore the Red Sea, the Gulf of Aden, the Afar Depression and the Main Ethiopian Rift to development of a new model that adopts two poles of rotation for Arabia. Second, the 4DPlates is used to model regional-scale and local-scale kinematics within the Afar Depression. Most plate reconstruction models of the Afro-Arabian Rift System relies on considering the Afar Depression as a typical rift-rift-rift triple junction where the Arabian, Somali and Nubian (African) plates are separating by the Red Sea, the Gulf of Aden and the Main Ethiopian Rift suggesting the presence of "sharp and rigid" plate boundaries. However, at the regional-scale the Afar kinematics are more complex due to stepping of the Red Sea propagator and the Gulf of Aden propagator onto Afar as well as the presence of the Danakil, Ali Sabieh and East Central Block "micro-plates". This study incorporates the motion of these micro-plates into the regional-scale model and defined the plate boundary between the Arabian and the African plates within Afar as likely a diffused zone of extensional strain within the East Central Block. Third, DInSAR technology is used to create ascending and descending differential interferograms from the Envisat Advanced Synthetic Aperture Radar (ASAR) C-Band data for the East Central Block to image active crustal deformation related to extensional tectonics and volcanism. Results of the DInSAR study indicate no strong strain localization but rather a diffused pattern of deformation across the entire East Central Block.

Low-energy ion acceleration at quasi-perpendicular shocks: Transverse diffusion

NASA Technical Reports Server (NTRS)

Giacalone, J.; Jokipii, J. R.

1995-01-01

The problem of ion injection and acceleration at quasi perpendicular shocks has been the subject of some debate over the past two decades. It is widely known that these shocks efficiently accelerate particles that are well in the high-energy tail of the distribution. However, the issue of injection, or the acceleration of low-energy ions, has yet to reach a consensus. The fundamental issue is whether there is enough diffusion normal to the magnetic field for the particles to remain near the shock. Since transverse diffusion is a physical process that is not well understood in space plasmas, this is an important, and difficult issue to address. In this report, we will investigate the ion injection problem by performing test particle orbit integrations using synthesized turbulent fields. These fields are fully three-dimensional so that transverse diffusion is possible (cross-field diffusion is not possible in geometries where the electromagnetic fields are less than three dimensional). The synthesized fields are produced by superimposing a three-dimensional wave field on a background field. For completeness, we will compare the results from this model with the more well-established theories, such as the diffusive approximation and scatter-free shock drift acceleration. We will also compare these results with other numerical simulation techniques such as the well known hybrid simulation, and other test-particle calculations in which the shock fields are specified to have less than three dimensions. We will also discuss some recent relevant observations and how these compare with our results.

78 FR 75371 - Diffusion-Annealed, Nickel-Plated Flat-Rolled Steel Products From Japan; Scheduling of the Final...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-11

...-Plated Flat-Rolled Steel Products From Japan; Scheduling of the Final Phase of an Antidumping... imports from Japan of diffusion-annealed, nickel- plated flat-rolled steel products, provided for... diffusion-annealed, nickel- plated flat-rolled steel products from Japan are being sold in the United States...

Three-dimensional wideband electromagnetic modeling on massively parallel computers

NASA Astrophysics Data System (ADS)

Alumbaugh, David L.; Newman, Gregory A.; Prevost, Lydie; Shadid, John N.

1996-01-01

A method is presented for modeling the wideband, frequency domain electromagnetic (EM) response of a three-dimensional (3-D) earth to dipole sources operating at frequencies where EM diffusion dominates the response (less than 100 kHz) up into the range where propagation dominates (greater than 10 MHz). The scheme employs the modified form of the vector Helmholtz equation for the scattered electric fields to model variations in electrical conductivity, dielectric permitivity and magnetic permeability. The use of the modified form of the Helmholtz equation allows for perfectly matched layer ( PML) absorbing boundary conditions to be employed through the use of complex grid stretching. Applying the finite difference operator to the modified Helmholtz equation produces a linear system of equations for which the matrix is sparse and complex symmetrical. The solution is obtained using either the biconjugate gradient (BICG) or quasi-minimum residual (QMR) methods with preconditioning; in general we employ the QMR method with Jacobi scaling preconditioning due to stability. In order to simulate larger, more realistic models than has been previously possible, the scheme has been modified to run on massively parallel (MP) computer architectures. Execution on the 1840-processor Intel Paragon has indicated a maximum model size of 280 × 260 × 200 cells with a maximum flop rate of 14.7 Gflops. Three different geologic models are simulated to demonstrate the use of the code for frequencies ranging from 100 Hz to 30 MHz and for different source types and polarizations. The simulations show that the scheme is correctly able to model the air-earth interface and the jump in the electric and magnetic fields normal to discontinuities. For frequencies greater than 10 MHz, complex grid stretching must be employed to incorporate absorbing boundaries while below this normal (real) grid stretching can be employed.

Measurement of the eddy diffusion term in chromatographic columns. I. Application to the first generation of 4.6mm I.D. monolithic columns.

PubMed

Gritti, Fabrice; Guiochon, Georges

2011-08-05

The corrected heights equivalent to a theoretical plate (HETP) of three 4.6mm I.D. monolithic Onyx-C(18) columns (Onyx, Phenomenex, Torrance, CA) of different lengths (2.5, 5, and 10 cm) are reported for retained (toluene, naphthalene) and non-retained (uracil, caffeine) small molecules. The moments of the peak profiles were measured according to the accurate numerical integration method. Correction for the extra-column contributions was systematically applied. The peak parking method was used in order to measure the bulk diffusion coefficients of the sample molecules, their longitudinal diffusion terms, and the eddy diffusion term of the three monolithic columns. The experimental results demonstrate that the maximum efficiency was 60,000 plates/m for retained compounds. The column length has a large impact on the plate height of non-retained species. These observations were unambiguously explained by a large trans-column eddy diffusion term in the van Deemter HETP equation. This large trans-rod eddy diffusion term is due to the combination of a large trans-rod velocity bias (≃3%), a small radial dispersion coefficient in silica monolithic columns, and a poorly designed distribution and collection of the sample streamlets at the inlet and outlet of the monolithic rod. Improving the performance of large I.D. monolithic columns will require (1) a detailed knowledge of the actual flow distribution across and along these monolithic rod and (2) the design of appropriate inlet and outlet distributors designed to minimize the nefarious impact of the radial flow heterogeneity on band broadening. Copyright © 2011 Elsevier B.V. All rights reserved.

An efficient three-dimensional Poisson solver for SIMD high-performance-computing architectures

NASA Technical Reports Server (NTRS)

Cohl, H.

1994-01-01

We present an algorithm that solves the three-dimensional Poisson equation on a cylindrical grid. The technique uses a finite-difference scheme with operator splitting. This splitting maps the banded structure of the operator matrix into a two-dimensional set of tridiagonal matrices, which are then solved in parallel. Our algorithm couples FFT techniques with the well-known ADI (Alternating Direction Implicit) method for solving Elliptic PDE's, and the implementation is extremely well suited for a massively parallel environment like the SIMD architecture of the MasPar MP-1. Due to the highly recursive nature of our problem, we believe that our method is highly efficient, as it avoids excessive interprocessor communication.

FORCE2: A state-of-the-art two-phase code for hydrodynamic calculations

NASA Astrophysics Data System (ADS)

Ding, Jianmin; Lyczkowski, R. W.; Burge, S. W.

1993-02-01

A three-dimensional computer code for two-phase flow named FORCE2 has been developed by Babcock and Wilcox (B & W) in close collaboration with Argonne National Laboratory (ANL). FORCE2 is capable of both transient as well as steady-state simulations. This Cartesian coordinates computer program is a finite control volume, industrial grade and quality embodiment of the pilot-scale FLUFIX/MOD2 code and contains features such as three-dimensional blockages, volume and surface porosities to account for various obstructions in the flow field, and distributed resistance modeling to account for pressure drops caused by baffles, distributor plates and large tube banks. Recently computed results demonstrated the significance of and necessity for three-dimensional models of hydrodynamics and erosion. This paper describes the process whereby ANL's pilot-scale FLUFIX/MOD2 models and numerics were implemented into FORCE2. A description of the quality control to assess the accuracy of the new code and the validation using some of the measured data from Illinois Institute of Technology (UT) and the University of Illinois at Urbana-Champaign (UIUC) are given. It is envisioned that one day, FORCE2 with additional modules such as radiation heat transfer, combustion kinetics and multi-solids together with user-friendly pre- and post-processor software and tailored for massively parallel multiprocessor shared memory computational platforms will be used by industry and researchers to assist in reducing and/or eliminating the environmental and economic barriers which limit full consideration of coal, shale and biomass as energy sources, to retain energy security, and to remediate waste and ecological problems.

Comparative Three‐Dimensional Morphology of Baleen: Cross‐Sectional Profiles and Volume Measurements Using CT Images

PubMed Central

Saladrigas, Amalia H.; Goldbogen, Jeremy A.

2017-01-01

ABSTRACT Baleen whales are obligate filter feeders, straining prey‐laden seawater through racks of keratinized baleen plates. Despite the importance of baleen to the ecology and natural history of these animals, relatively little work has been done on baleen morphology, particularly with regard to the three‐dimensional morphology and structure of baleen. We used computed tomography (CT) scanning to take 3D images of six baleen specimens representing five species, including three complete racks. With these images, we described the three‐dimensional shape of the baleen plates using cross‐sectional profiles from within the gum tissue to the tip of the plates. We also measured the percentage of each specimen that was composed of either keratinized plate material or was void space between baleen plates, and thus available for seawater flow. Baleen plates have a complex three‐dimensional structure with curvature that varies across the anterior‐posterior, proximal‐distal, and medial‐lateral (lingual‐labial) axes. These curvatures also vary with location along the baleen rack, and between species. Cross‐sectional profiles resemble backwards‐facing airfoils, and some specimens display S‐shaped, or reflexed, camber. Within a baleen specimen, the intra‐baleen void volume correlates with the average bristle diameter for a species, suggesting that essentially, thinner plates (with more space between them for flow) have thinner bristles. Both plate curvature and the relative proportions of plate and void volumes are likely to have implications for the mechanics of mysticete filtration, and future studies are needed to determine the particular functions of these morphological characters. Anat Rec, 300:1942–1952, 2017. © 2017 The Authors The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists PMID:28971628

Thermal limitations in a rapid-fire multirail launcher powered by a pulsed magnetodhydrodynamic generator

NASA Astrophysics Data System (ADS)

Stankevich, S. V.; Shvetsov, G. A.; Butov, V. G.; Sinyaev, S. V.

2017-09-01

The operation of rapid burst firing multirail electromagnetic launchers of solids is numerically simulated using unsteady two-dimensional and three-dimensional models. In the calculations, the launchers are powered by a Sakhalin pulsed magnetohydrodynamic generator. Launchers with three and five pairs of parallel rails connected in a series electrical circuit are considered. Firing sequences of different numbers of solid projectiles of different masses is modeled. It is established that the heating of the rails is one of the main factors limiting the performance of launchers under such conditions. It is shown that the rate of heating of the rails is determined by the nonuniformity of the current density distribution over the rail cross-section due to the unsteady diffusion of the magnetic field into the rails. Calculations taking into account the unsteady current density distribution in the rails of a multirail launcher show that with an appropriate of the mass of the projectiles (up to 800 g), their number in the sequence, and the material of the rails, it is possible to attain launching velocities of 1.8-2.5 km/s with moderate heating of the rails.

Three-dimensional finite amplitude electroconvection in dielectric liquids

NASA Astrophysics Data System (ADS)

Luo, Kang; Wu, Jian; Yi, Hong-Liang; Tan, He-Ping

2018-02-01

Charge injection induced electroconvection in a dielectric liquid lying between two parallel plates is numerically simulated in three dimensions (3D) using a unified lattice Boltzmann method (LBM). Cellular flow patterns and their subcritical bifurcation phenomena of 3D electroconvection are numerically investigated for the first time. A unit conversion is also derived to connect the LBM system to the real physical system. The 3D LBM codes are validated by three carefully chosen cases and all results are found to be highly consistent with the analytical solutions or other numerical studies. For strong injection, the steady state roll, polygon, and square flow patterns are observed under different initial disturbances. Numerical results show that the hexagonal cell with the central region being empty of charge and centrally downward flow is preferred in symmetric systems under random initial disturbance. For weak injection, the numerical results show that the flow directly passes from the motionless state to turbulence once the system loses its linear stability. In addition, the numerically predicted linear and finite amplitude stability criteria of different flow patterns are discussed.

Proxy-equation paradigm: A strategy for massively parallel asynchronous computations

NASA Astrophysics Data System (ADS)

Mittal, Ankita; Girimaji, Sharath

2017-09-01

Massively parallel simulations of transport equation systems call for a paradigm change in algorithm development to achieve efficient scalability. Traditional approaches require time synchronization of processing elements (PEs), which severely restricts scalability. Relaxing synchronization requirement introduces error and slows down convergence. In this paper, we propose and develop a novel "proxy equation" concept for a general transport equation that (i) tolerates asynchrony with minimal added error, (ii) preserves convergence order and thus, (iii) expected to scale efficiently on massively parallel machines. The central idea is to modify a priori the transport equation at the PE boundaries to offset asynchrony errors. Proof-of-concept computations are performed using a one-dimensional advection (convection) diffusion equation. The results demonstrate the promise and advantages of the present strategy.

Stagnation point properties for non-continuum gaseous jet impinging at a flat plate surface from a planar exit

NASA Astrophysics Data System (ADS)

Cai, Chunpei

2013-10-01

In this paper, we investigate highly rarefied gaseous jet flows out of a planar exit and impinging at a normally set flat plate. Especially, we concentrate on the plate center stagnation point pressure and heat flux coefficients. For a specular reflective plate, the stagnation point pressure coefficient can be represented using two non-dimensional factors: the characteristic gas exit speed ratio S0 and the geometry ratio of H/L, where H is the planar exit semi-height and L is the center-to-center distance from the exit to the plate. For a diffuse reflective plate, the stagnation point pressure and heat flux coefficients involve an extra factor of T0/Tw, i.e., the ratio of exit gas temperature to the plate wall temperature. These results allow us to develop four diagrams, from which we can conveniently obtain the pressure and heat flux coefficients for the stagnation impingement point, at the collisionless flow limit. After normalization with these maximum coefficients, the pressure and heat flux coefficient distributions along the surface essentially degenerate to almost identical curves. As a result, with known plate surface pressure coefficient distributions and these diagrams, we can conveniently construct the heat flux coefficient distributions along the plate surface, and vice versa.

Parallel computation of fluid-structural interactions using high resolution upwind schemes

NASA Astrophysics Data System (ADS)

Hu, Zongjun

An efficient and accurate solver is developed to simulate the non-linear fluid-structural interactions in turbomachinery flutter flows. A new low diffusion E-CUSP scheme, Zha CUSP scheme, is developed to improve the efficiency and accuracy of the inviscid flux computation. The 3D unsteady Navier-Stokes equations with the Baldwin-Lomax turbulence model are solved using the finite volume method with the dual-time stepping scheme. The linearized equations are solved with Gauss-Seidel line iterations. The parallel computation is implemented using MPI protocol. The solver is validated with 2D cases for its turbulence modeling, parallel computation and unsteady calculation. The Zha CUSP scheme is validated with 2D cases, including a supersonic flat plate boundary layer, a transonic converging-diverging nozzle and a transonic inlet diffuser. The Zha CUSP2 scheme is tested with 3D cases, including a circular-to-rectangular nozzle, a subsonic compressor cascade and a transonic channel. The Zha CUSP schemes are proved to be accurate, robust and efficient in these tests. The steady and unsteady separation flows in a 3D stationary cascade under high incidence and three inlet Mach numbers are calculated to study the steady state separation flow patterns and their unsteady oscillation characteristics. The leading edge vortex shedding is the mechanism behind the unsteady characteristics of the high incidence separated flows. The separation flow characteristics is affected by the inlet Mach number. The blade aeroelasticity of a linear cascade with forced oscillating blades is studied using parallel computation. A simplified two-passage cascade with periodic boundary condition is first calculated under a medium frequency and a low incidence. The full scale cascade with 9 blades and two end walls is then studied more extensively under three oscillation frequencies and two incidence angles. The end wall influence and the blade stability are studied and compared under different frequencies and incidence angles. The Zha CUSP schemes are the first time to be applied in moving grid systems and 2D and 3D calculations. The implicit Gauss-Seidel iteration with dual time stepping is the first time to be used for moving grid systems. The NASA flutter cascade is the first time to be calculated in full scale.

Pull-Apart vs. Subduction Rollback Mechanisms For The Cenozoic Formation Of Bohai Basin, Eastern China

NASA Astrophysics Data System (ADS)

Castellanos, H. A.; Mann, P.

2005-12-01

The Bohai basin of eastern China covers an area of about 200,000 km2 and forms one of a family of basins that record Cenozoic extension along the eastern margin of Asia from Viet Nam to northeastern Russia. Two very different deformational mechanisms have been proposed for the Cenozoic formation of the Bohai basin. The first model proposes a two-stage extension model consisting of Paleogene rifting in a WNW-ESE direction followed by Neogene thermal subsidence that controlled overlying and less deformed sag basins above the rifted section (Ye et al., 1985). The mechanism for two-stage rifting is generally attributed to rollback of the subducted Pacific plate beneath the Asian continent, lithospheric extension of the overriding continental plate, and thermally-driven, regional subsidence. A second model invokes a more localized Cenozoic pull-apart basin formed at a right-step in a right-lateral shear system parallel to the Asian continental margin (Allen et al., 1997). Earthquakes and GPS data indicate that right-lateral strike-slip faulting continues to the present-day in a pattern consistent with the regional-scale "lazy-Z" map pattern of the Cenozoic Bohai depocenter. Allen et al. (1997) propose the subsurface of the large pull-apart structure contains diffuse, sub-parallel strike-slip faults offset by smaller-scale, intrabasinal stepovers. In order to better distinguish the timing and mechanism for the formation of the Bohai basin, we have interpreted 1400 km of offshore 2D seismic data, a 3D seismic volume, and integrated lithostratigraphic data from 6 wells that are tied to these reflection data. Three major units were identified and mapped on a basin-wide scale: basement, a syn-rift unit, and a post-rift sag unit. Thickening trends and ages indicate the syn-rift phase occurred from late Paleocene to late Oligocene. Basin opening occurred on a series of half-grabens trending NNE-SSW. Rifting ended during the late Oligocene when a regional uplift and erosional event affected the basin. The Miocene to recent was marked by the formation of sag basins deformed by widely-spaced strike-slip faults. These active strike-slip faults are commonly localized on earlier normal faults. Given these observations a three stage basin history is proposed: 1) Eocene-late Oligocene basin opening across a diffuse set of half-grabens; the pattern of rifts supports a regional extension possibly related to subduction rollback of the Pacific plate; 2) a late Oligocene uplift and erosional event of unknown origin; and 3) late Oligocene to recent strike-slip faulting; the regional-scale "lazy-Z" map pattern of Bohai depocenter indicates the importance of right-stepping pull-apart control on the younger sag section.

Biodynamic profiling of three-dimensional tissue growth techniques

NASA Astrophysics Data System (ADS)

Sun, Hao; Merrill, Dan; Turek, John; Nolte, David

2016-03-01

Three-dimensional tissue culture presents a more biologically relevant environment in which to perform drug development than conventional two-dimensional cell culture. However, obtaining high-content information from inside three dimensional tissue has presented an obstacle to rapid adoption of 3D tissue culture for pharmaceutical applications. Biodynamic imaging is a high-content three-dimensional optical imaging technology based on low-coherence interferometry and digital holography that uses intracellular dynamics as high-content image contrast. In this paper, we use biodynamic imaging to compare pharmaceutical responses to Taxol of three-dimensional multicellular spheroids grown by three different growth techniques: rotating bioreactor, hanging-drop and plate-grown spheroids. The three growth techniques have systematic variations among tissue cohesiveness and intracellular activity and consequently display different pharmacodynamics under identical drug dose conditions. The in vitro tissue cultures are also compared to ex vivo living biopsies. These results demonstrate that three-dimensional tissue cultures are not equivalent, and that drug-response studies must take into account the growth method.

Improved tests of extra-dimensional physics and thermal quantum field theory from new Casimir force measurements

NASA Astrophysics Data System (ADS)

Decca, R. S.; Fischbach, E.; Klimchitskaya, G. L.; Krause, D. E.; López, D.; Mostepanenko, V. M.

2003-12-01

We report new constraints on extra-dimensional models and other physics beyond the standard model based on measurements of the Casimir force between two dissimilar metals for separations in the range 0.2 1.2 μm. The Casimir force between a Au-coated sphere and a Cu-coated plate of a microelectromechanical torsional oscillator was measured statically with an absolute error of 0.3 pN. In addition, the Casimir pressure between two parallel plates was determined dynamically with an absolute error of ≈0.6 mPa. Within the limits of experimental and theoretical errors, the results are in agreement with a theory that takes into account the finite conductivity and roughness of the two metals. The level of agreement between experiment and theory was then used to set limits on the predictions of extra-dimensional physics and thermal quantum field theory. It is shown that two theoretical approaches to the thermal Casimir force which predict effects linear in temperature are ruled out by these experiments. Finally, constraints on Yukawa corrections to Newton’s law of gravity are strengthened by more than an order of magnitude in the range 56 330 nm.

Fully customized placement of orthodontic miniplates: a novel clinical technique

PubMed Central

2014-01-01

Introduction The initial stability and survival rate of orthodontic mini-implants are highly dependent on the amount of cortical bone at their insertion site. In areas with limited bone availability, mini-plates are preferred to provide effective skeletal anchorage. The purpose of this paper was to present a new clinical technique for the insertion of mini-plates. Methods In order to apply this new technique, a cone-beam image of the insertion area is required. A software (Galaxy Sirona, Bensheim, Germany) is used to construct a three-dimensional image of the scanned area and to virtually determine the exact location of the mini-plate as well as the position of the fixation screws. A stereolithographic model (STL) is then created by means of a three-dimensional scanner. Prior to its surgical insertion, the bone plate is adapted to the stereo-lithographic model. Finally, a custom transfer jig is fabricated in order to assist with accurate placement of the mini-plate intra-operatively. Results The presented technique minimizes intra-operative decision making, because the final position of the bone plate is determined pre-surgically. This significantly reduces the duration of the surgical procedure and improves its outcome. Conclusions A novel method for surgical placement of orthodontic mini-plates is presented. The technique facilitates accurate adaptation of mini-plates and insertion of retaining surgical screws; thereby enabling clinicians to more confidently increase the use of bone plates, especially in anatomical areas where the success of non-osseointegrated mini-screws is less favorable. PMID:24886597

Geometrically nonlinear analysis of layered composite plates and shells

NASA Technical Reports Server (NTRS)

Chao, W. C.; Reddy, J. N.

1983-01-01

A degenerated three dimensional finite element, based on the incremental total Lagrangian formulation of a three dimensional layered anisotropic medium was developed. Its use in the geometrically nonlinear, static and dynamic, analysis of layered composite plates and shells is demonstrated. A two dimenisonal finite element based on the Sanders shell theory with the von Karman (nonlinear) strains was developed. It is shown that the deflections obtained by the 2D shell element deviate from those obtained by the more accurate 3D element for deep shells. The 3D degenerated element can be used to model general shells that are not necessarily doubly curved. The 3D degenerated element is computationally more demanding than the 2D shell theory element for a given problem. It is found that the 3D element is an efficient element for the analysis of layered composite plates and shells undergoing large displacements and transient motion.

Piezoelectrically forced vibrations of rectangular SC-cut quartz plates

NASA Astrophysics Data System (ADS)

Lee, P. C. Y.; Lin, W. S.

1998-06-01

A system of two-dimensional first-order equations for piezoelectric crystal plates with general symmetry and with electroded faces was recently deduced from the three-dimensional equations of linear piezoelectricity. Solutions of these equations for AT-cut plates of quartz were shown to give accurate dispersion curves without corrections, and the resonances predicted agree closely with the experimental data of Koga and Fukuyo [I. Koga and H. Fukuyo, J. Inst. Electr. Commun. Eng. Jpn. 36, 59 (1953)] and that of Nakazawa, Horiuchi, and Ito (M. Nakazawa, K. Horiuchi, and H. Ito, Proceedings of the 1990 IEEE Ultrasonics Symposium, pp. 547-555). In this article, these equations are employed to study the free as well as the forced vibrations of doubly rotated quartz plates. Solutions of straight-crested vibrational modes varying in the x1 and x3 directions of SC-cut quartz plates of infinite extent are obtained and from which dispersion curves are computed. Comparison of those dispersion curves with those from the three-dimensional equations shows that the agreement is very close without any corrections. Resonance frequencies for free vibrations and capacitance ratios for piezoelectrically forced vibrations are computed and examined for various length-to-thickness or width-to-thickness ratios of rectangular SC-cut quartz plates. The capacitance ratio as a function of forcing frequency is computed for a rectangular AT-cut quartz and compared with the experimental data of Seikimoto, Watanabe, and Nakazawa (H. Sekimoto, Y. Watanabe, and M. Nakazawa, Proceedings of the 1992 IEEE Frequency Control Symposium, pp. 532-536) and is in close agreement.

Parallel Visualization of Large-Scale Aerodynamics Calculations: A Case Study on the Cray T3E

NASA Technical Reports Server (NTRS)

Ma, Kwan-Liu; Crockett, Thomas W.

1999-01-01

This paper reports the performance of a parallel volume rendering algorithm for visualizing a large-scale, unstructured-grid dataset produced by a three-dimensional aerodynamics simulation. This dataset, containing over 18 million tetrahedra, allows us to extend our performance results to a problem which is more than 30 times larger than the one we examined previously. This high resolution dataset also allows us to see fine, three-dimensional features in the flow field. All our tests were performed on the Silicon Graphics Inc. (SGI)/Cray T3E operated by NASA's Goddard Space Flight Center. Using 511 processors, a rendering rate of almost 9 million tetrahedra/second was achieved with a parallel overhead of 26%.

Flat-plate solar array project process development area: Process research of non-CZ silicon material

NASA Technical Reports Server (NTRS)

Campbell, R. B.

1986-01-01

Several different techniques to simultaneously diffuse the front and back junctions in dendritic web silicon were investigated. A successful simultaneous diffusion reduces the cost of the solar cell by reducing the number of processing steps, the amount of capital equipment, and the labor cost. The three techniques studied were: (1) simultaneous diffusion at standard temperatures and times using a tube type diffusion furnace or a belt furnace; (2) diffusion using excimer laser drive-in; and (3) simultaneous diffusion at high temperature and short times using a pulse of high intensity light as the heat source. The use of an excimer laser and high temperature short time diffusion experiment were both more successful than the diffusion at standard temperature and times. The three techniques are described in detail and a cost analysis of the more successful techniques is provided.

Dynamic behaviour of thin composite plates for different boundary conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sprintu, Iuliana, E-mail: sprintui@yahoo.com, E-mail: rotaruconstantin@yahoo.com; Rotaru, Constantin, E-mail: sprintui@yahoo.com, E-mail: rotaruconstantin@yahoo.com

2014-12-10

In the context of composite materials technology, which is increasingly present in industry, this article covers a topic of great interest and theoretical and practical importance. Given the complex design of fiber-reinforced materials and their heterogeneous nature, mathematical modeling of the mechanical response under different external stresses is very difficult to address in the absence of simplifying assumptions. In most structural applications, composite structures can be idealized as beams, plates, or shells. The analysis is reduced from a three-dimensional elasticity problem to a oneor two-dimensional problem, based on certain simplifying assumptions that can be made because the structure is thin.more » This paper aims to validate a mathematical model illustrating how thin rectangular orthotropic plates respond to the actual load. Thus, from the theory of thin plates, new analytical solutions are proposed corresponding to orthotropic rectangular plates having different boundary conditions. The proposed analytical solutions are considered both for solving equation orthotropic rectangular plates and for modal analysis.« less

Time dependent deformation and stress in the lithosphere. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Yang, M.

1980-01-01

Efficient computer programs incorporating frontal solution and time stepping procedure were developed for the modelling of geodynamic problems. This scheme allows for investigating the quasi static phenomena including the effects of the rheological structure of a tectonically active region. From three dimensional models of strike slip earthquakes, it was found that lateral variation of viscosity affects the characteristics of surface deformations. The vertical deformation is especially informative about the viscosity structure in a strike slip fault zone. A three dimensional viscoelastic model of a thrust earthquake indicated that the transient disturbance on plate velocity due to a great plate boundary earthquake is significant at intermediate distances, but becomes barely measurable 1000 km away from the source.

Three Dimensional Forming Simulation of the Shielded Slot Plate for the MCFC Using a Ductile Fracture Criterion

NASA Astrophysics Data System (ADS)

Lee, C. H.; Yang, D. Y.; Lee, S. R.; Chang, I. G.; Lee, T. W.

2011-08-01

The shielded slot plate, which has a sheared corrugated trapezoidal pattern, is a component of the metallic bipolar plate for the molten carbonate fuel cell (MCFC). In order to increase the efficiency of the fuel cell, the unit cell of the shielded slot plate should have a relatively large upper area. Additionally, defects from the forming process should be minimized. In order to simulate the slitting process, whereby sheared corrugated patterns are formed, ductile fracture criteria based on the histories of stress and strain are employed. The user material subroutine VUMAT is employed for implementation of the material and ductile fracture criteria in the commercial FEM software ABAQUS. The variables of the ductile fracture criteria were determined by comparing the simulation results and the experimental results of the tension test and the shearing test. Parametric studies were conducted to determine the critical value of the ductile fracture criterion. Employing these ductile fracture criteria, the three dimensional forming process of the shielded slot plate was numerically simulated. The effects of the slitting process in the forming process of the shielded slot plate were analyzed through a FEM simulation and experimental studies. Finally, experiments involving microscopic and macroscopic observations were conducted to verify the numerical simulations of the 3-step forming process.

Biomechanical Property of a Newly Designed Assembly Locking Compression Plate: Three-Dimensional Finite Element Analysis

PubMed Central

Liu, Da

2017-01-01

In this study, we developed and validated a refined three-dimensional finite element model of middle femoral comminuted fracture to compare the biomechanical stability after two kinds of plate fixation: a newly designed assembly locking compression plate (NALCP) and a locking compression plate (LCP). CT data of a male volunteer was converted to middle femoral comminuted fracture finite element analysis model. The fracture was fixated by NALCP and LCP. Stress distributions were observed. Under slow walking load and torsion load, the stress distribution tendency of the two plates was roughly uniform. The anterolateral femur was the tension stress area, and the bone block shifted toward the anterolateral femur. Maximum stress was found on the lateral border of the number 5 countersink of the plate. Under a slow walking load, the NALCP maximum stress was 2.160e+03 MPa and the LCP was 8.561e+02 MPa. Under torsion load, the NALCP maximum stress was 2.260e+03 MPa and the LCP was 6.813e+02 MPa. Based on those results of finite element analysis, the NALCP can provide adequate mechanical stability for comminuted fractures, which would help fixate the bone block and promote bone healing. PMID:29065654

Three-Dimensional Modeling of Fluid and Heat Transport in an Accretionary Complex

NASA Astrophysics Data System (ADS)

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.

The Experimental Study of Rayleigh-Taylor Instability using a Linear Induction Motor Accelerator

NASA Astrophysics Data System (ADS)

Yamashita, Nicholas; Jacobs, Jeffrey

2009-11-01

The experiments to be presented utilize an incompressible system of two stratified miscible liquids of different densities that are accelerated in order to produce the Rayleigh-Taylor instability. Three liquid combinations are used: isopropyl alcohol with water, a calcium nitrate solution or a lithium polytungstate solution, giving Atwood numbers of 0.11, 0.22 and 0.57, respectively. The acceleration required to drive the instability is produced by two high-speed linear induction motors mounted to an 8 m tall drop tower. The motors are mounted in parallel and have an effective acceleration length of 1.7 m and are each capable of producing 15 kN of thrust. The liquid system is contained within a square acrylic tank with inside dimensions 76 x76x184 mm. The tank is mounted to an aluminum plate, which is driven by the motors to create constant accelerations in the range of 1-20 g's, though the potential exists for higher accelerations. Also attached to the plate are a high-speed camera and an LED backlight to provide continuous video of the instability. In addition, an accelerometer is used to provide acceleration measurements during each experiment. Experimental image sequences will be presented which show the development of a random three-dimensional instability from an unforced initial perturbation. Measurements of the mixing zone width will be compared with traditional growth models.

Development of an automated large-scale protein-crystallization and monitoring system for high-throughput protein-structure analyses.

PubMed

Hiraki, Masahiko; Kato, Ryuichi; Nagai, Minoru; Satoh, Tadashi; Hirano, Satoshi; Ihara, Kentaro; Kudo, Norio; Nagae, Masamichi; Kobayashi, Masanori; Inoue, Michio; Uejima, Tamami; Oda, Shunichiro; Chavas, Leonard M G; Akutsu, Masato; Yamada, Yusuke; Kawasaki, Masato; Matsugaki, Naohiro; Igarashi, Noriyuki; Suzuki, Mamoru; Wakatsuki, Soichi

2006-09-01

Protein crystallization remains one of the bottlenecks in crystallographic analysis of macromolecules. An automated large-scale protein-crystallization system named PXS has been developed consisting of the following subsystems, which proceed in parallel under unified control software: dispensing precipitants and protein solutions, sealing crystallization plates, carrying robot, incubators, observation system and image-storage server. A sitting-drop crystallization plate specialized for PXS has also been designed and developed. PXS can set up 7680 drops for vapour diffusion per hour, which includes time for replenishing supplies such as disposable tips and crystallization plates. Images of the crystallization drops are automatically recorded according to a preprogrammed schedule and can be viewed by users remotely using web-based browser software. A number of protein crystals were successfully produced and several protein structures could be determined directly from crystals grown by PXS. In other cases, X-ray quality crystals were obtained by further optimization by manual screening based on the conditions found by PXS.

Efficient electron open boundaries for simulating electrochemical cells

NASA Astrophysics Data System (ADS)

Zauchner, Mario G.; Horsfield, Andrew P.; Todorov, Tchavdar N.

2018-01-01

Nonequilibrium electrochemistry raises new challenges for atomistic simulation: we need to perform molecular dynamics for the nuclear degrees of freedom with an explicit description of the electrons, which in turn must be free to enter and leave the computational cell. Here we present a limiting form for electron open boundaries that we expect to apply when the magnitude of the electric current is determined by the drift and diffusion of ions in a solution and which is sufficiently computationally efficient to be used with molecular dynamics. We present tight-binding simulations of a parallel-plate capacitor with nothing, a dimer, or an atomic wire situated in the space between the plates. These simulations demonstrate that this scheme can be used to perform molecular dynamics simulations when there is an applied bias between two metal plates with, at most, weak electronic coupling between them. This simple system captures some of the essential features of an electrochemical cell, suggesting this approach might be suitable for simulations of electrochemical cells out of equilibrium.

Electrochemical Device Comprising Composite Bipolar Plate and Method of Using the Same

NASA Technical Reports Server (NTRS)

Mittelsteadt, Cortney K. (Inventor); Braff, William A. (Inventor)

2013-01-01

An electrochemical device and methods of using the same. In one embodiment, the electrochemical device may be used as a fuel cell and/or as an electrolyzer and includes a membrane electrode assembly (MEA), an anodic gas diffusion medium in contact with the anode of the MEA, a cathodic gas diffusion medium in contact with the cathode, a first bipolar plate in contact with the anodic gas diffusion medium, and a second bipolar plate in contact with the cathodic gas diffusion medium. Each of the bipolar plates includes an electrically-conductive, chemically-inert, non-porous, liquid-permeable, substantially gas-impermeable membrane in contact with its respective gas diffusion medium, as well as a fluid chamber and a non-porous an electrically-conductive plate.

Electrochemical Device Comprising Composite Bipolar Plate and Method of Using the Same

NASA Technical Reports Server (NTRS)

Mittelsteadt, Cortney K. (Inventor); Braff, William A. (Inventor)

2017-01-01

An electrochemical device and methods of using the same. In one embodiment, the electrochemical device may be used as a fuel cell and/or as an electrolyzer and includes a membrane electrode assembly (MEA), an anodic gas diffusion medium in contact with the anode of the MEA, a cathodic gas diffusion medium in contact with the cathode, a first bipolar plate in contact with the anodic gas diffusion medium, and a second bipolar plate in contact with the cathodic gas diffusion medium. Each of the bipolar plates includes an electrically-conductive, chemically-inert, non-porous, liquid-permeable, substantially gas-impermeable membrane in contact with its respective gas diffusion medium, as well as a fluid chamber and a non-porous an electrically-conductive plate.

Modeling the role of back-arc spreading in controlling 3-D circulation and temperature patterns in subduction zones

NASA Astrophysics Data System (ADS)

Kincaid, C.

2005-12-01

Subduction of oceanic lithosphere provides a dominant driving force for mantle dynamics and plate tectonics, and strongly modulates the thermal evolution of the mantle. Magma generation in arc environments is related to slab temperatures, slab dehydration/wedge hydration processes and circulation patterns in the mantle wedge. A series of laboratory experiments is used to model three-dimensional aspects of flow in subduction zones, and the consequent temperature variations in the slab and overlying mantle wedge. The experiments utilize a tank of glucose syrup to simulate the mantle and a Phenolic plate to represent subducting oceanic lithosphere. Different modes of plate sinking are produced using hydraulic pistons. The effects of longitudinal, rollback and slab-steepening components of slab motions are considered, along with different thicknesses of the over-riding lithosphere. Models look specifically at how distinct modes of back-arc spreading alter subduction zone temperatures and flow in the mantle wedge. Results show remarkably different temperature and circulation patterns when spreading is produced by rollback of the trench-slab-arc relative to a stationary overriding back-arc plate versus spreading due to motion of the overriding plate away from a fixed trench location. For rollback-induced spreading, flow trajectories in the wedge are shallow (e.g., limited upwelling), both the sub-arc and back-arc regions are supplied by material flowing around the receding slab. Flow lines in the sub-arc wedge are strongly trench-parallel. In these cases, strong lateral variations in slab surface temperature (SST) are recorded (hot at plate center, cool at plate edge). When the trench is fixed in space and spreading is produced by motion of the overriding plate, strong vertical flow velocities are recorded in the wedge, both the shallow sub-arc and back-arc regions are supplied by flow from under the overriding plate producing strong vertical shear. In these cases SSTs are nearly uniform across the plate. Results have implications for geochemical and seismic models of 3-D flow in subduction zones influenced by back-arc spreading, such as the Marianas.

Quantitative Three-Dimensional Imaging of Heterogeneous Materials by Thermal Tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, J. G.

2016-07-19

Infrared thermal imaging based on active thermal excitations has been widely used for nondestructive evaluation ( NDE) of materials. While the experimental systems have remained essentially the same during the last few decades, development of advanced data-processing methods has significantly improved the capabilities of this technology. However, many limitations still exist. One fundamental limitation is the requirement, either explicitly or implicitly, of the tested material to be homogeneous such that detected thermal contrasts may be used to determine an average material property or attributed to flaws. In this paper, a new thermal tomography ( TT) method is introduced, which formore » the first time can evaluate heterogeneous materials by directly imaging their thermal-property variations with space. It utilizes one-sided flash thermal-imaging data to construct the three-dimensional ( 3D) distribution of thermal effusivity in the entire volume of a test sample. Theoretical analyses for single and multilayer material systems were conducted to validate its formulation and to demonstrate its performance. Experimental results for a ceramic composite plate and a thermal barrier coating ( TBC) sample are also presented. It was shown that thermal diffusion is the primary factor that degrades the spatial resolution with depth for TT; the spatial resolutions in the lateral and axial directions were quantitatively evaluated.« less

A broadband polarization-insensitive cloak based on mode conversion

PubMed Central

Gu, Chendong; Xu, Yadong; Li, Sucheng; Lu, Weixin; Li, Jensen; Chen, Huanyang; Hou, Bo

2015-01-01

In this work, we demonstrate an one-dimensional cloak consisting of parallel-plated waveguide with two slabs of gradient index metamaterials attached to its metallic walls. In it objects are hidden without limitation of polarizations, and good performance is observed for a broadband of frequencies. The experiments at microwave frequencies are carried out, supporting the theoretical results very well. The essential principle behind the proposed cloaking device is based on mode conversion, which provides a new strategy to manipulate wave propagation. PMID:26175114

Continuous Diffusion Flames and Flame Streets in Micro-Channels

NASA Astrophysics Data System (ADS)

Mohan, Shikhar; Matalon, Moshe

2015-11-01

Experiments of non-premixed combustion in micro-channels have shown different modes of burning. Normally, a flame is established along, or near the axis of a channel that spreads the entire mixing layer and separates a region of fuel but no oxidizer from a region with only oxidizer. Often, however, a periodic sequence of extinction and reignition events, termed collectively as ``flame streets'', are observed. They constitute a series of diffusion flames, each with a tribrachial leading edge stabilized along the channel. This work focuses on understanding the underlying mechanism responsible for these distinct observations. Numerical simulations were conducted in the thermo-diffusive limit in order to study the effects of confinement and heat loss on non-premixed flames in three-dimensional micro-channels with low aspect ratios. The three dimensionality of the channel was captured qualitatively through a systematic asymptotic analysis that led to a two dimensional problem with an effective parameter representing heat losses in the vertical direction. There exist three key flame regimes: (1) a stable continuous diffusion flame, (2) an unsteady flame, and (3) a stable ``flame street'' the transition between regimes demarcated primarily by Reynolds and Nusselt numbers.

ANALYTICAL SOLUTIONS OF THE ATMOSPHERIC DIFFUSION EQUATION WITH MULTIPLE SOURCES AND HEIGHT-DEPENDENT WIND SPEED AND EDDY DIFFUSIVITIES. (R825689C072)

EPA Science Inventory

Abstract

Three-dimensional analytical solutions of the atmospheric diffusion equation with multiple sources and height-dependent wind speed and eddy diffusivities are derived in a systematic fashion. For homogeneous Neumann (total reflection), Dirichlet (total adsorpti...

ANALYTICAL SOLUTIONS OF THE ATMOSPHERIC DIFFUSION EQUATION WITH MULTIPLE SOURCES AND HEIGHT-DEPENDENT WIND SPEED AND EDDY DIFFUSIVITIES. (R825689C048)

EPA Science Inventory

Abstract

Three-dimensional analytical solutions of the atmospheric diffusion equation with multiple sources and height-dependent wind speed and eddy diffusivities are derived in a systematic fashion. For homogeneous Neumann (total reflection), Dirichlet (total adsorpti...

Large-scale parallel lattice Boltzmann-cellular automaton model of two-dimensional dendritic growth

NASA Astrophysics Data System (ADS)

Jelinek, Bohumir; Eshraghi, Mohsen; Felicelli, Sergio; Peters, John F.

2014-03-01

An extremely scalable lattice Boltzmann (LB)-cellular automaton (CA) model for simulations of two-dimensional (2D) dendritic solidification under forced convection is presented. The model incorporates effects of phase change, solute diffusion, melt convection, and heat transport. The LB model represents the diffusion, convection, and heat transfer phenomena. The dendrite growth is driven by a difference between actual and equilibrium liquid composition at the solid-liquid interface. The CA technique is deployed to track the new interface cells. The computer program was parallelized using the Message Passing Interface (MPI) technique. Parallel scaling of the algorithm was studied and major scalability bottlenecks were identified. Efficiency loss attributable to the high memory bandwidth requirement of the algorithm was observed when using multiple cores per processor. Parallel writing of the output variables of interest was implemented in the binary Hierarchical Data Format 5 (HDF5) to improve the output performance, and to simplify visualization. Calculations were carried out in single precision arithmetic without significant loss in accuracy, resulting in 50% reduction of memory and computational time requirements. The presented solidification model shows a very good scalability up to centimeter size domains, including more than ten million of dendrites. Catalogue identifier: AEQZ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEQZ_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, UK Licensing provisions: Standard CPC license, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 29,767 No. of bytes in distributed program, including test data, etc.: 3131,367 Distribution format: tar.gz Programming language: Fortran 90. Computer: Linux PC and clusters. Operating system: Linux. Has the code been vectorized or parallelized?: Yes. Program is parallelized using MPI. Number of processors used: 1-50,000 RAM: Memory requirements depend on the grid size Classification: 6.5, 7.7. External routines: MPI (http://www.mcs.anl.gov/research/projects/mpi/), HDF5 (http://www.hdfgroup.org/HDF5/) Nature of problem: Dendritic growth in undercooled Al-3 wt% Cu alloy melt under forced convection. Solution method: The lattice Boltzmann model solves the diffusion, convection, and heat transfer phenomena. The cellular automaton technique is deployed to track the solid/liquid interface. Restrictions: Heat transfer is calculated uncoupled from the fluid flow. Thermal diffusivity is constant. Unusual features: Novel technique, utilizing periodic duplication of a pre-grown “incubation” domain, is applied for the scaleup test. Running time: Running time varies from minutes to days depending on the domain size and number of computational cores.

Three-dimensional structure determination protocol for noncrystalline biomolecules using x-ray free-electron laser diffraction imaging.

PubMed

Oroguchi, Tomotaka; Nakasako, Masayoshi

2013-02-01

Coherent and intense x-ray pulses generated by x-ray free-electron laser (XFEL) sources are paving the way for structural determination of noncrystalline biomolecules. However, due to the small scattering cross section of electrons for x rays, the available incident x-ray intensity of XFEL sources, which is currently in the range of 10(12)-10(13) photons/μm(2)/pulse, is lower than that necessary to perform single-molecule diffraction experiments for noncrystalline biomolecules even with the molecular masses of megadalton and submicrometer dimensions. Here, we propose an experimental protocol and analysis method for visualizing the structure of those biomolecules by the combined application of coherent x-ray diffraction imaging and three-dimensional reconstruction methods. To compensate the small scattering cross section of biomolecules, in our protocol, a thin vitreous ice plate containing several hundred biomolecules/μm(2) is used as sample, a setup similar to that utilized by single-molecule cryoelectron microscopy. The scattering cross section of such an ice plate is far larger than that of a single particle. The images of biomolecules contained within irradiated areas are then retrieved from each diffraction pattern, and finally provide the three-dimensional electron density model. A realistic atomic simulation using large-scale computations proposed that the three-dimensional structure determination of the 50S ribosomal subunit embedded in a vitreous ice plate is possible at a resolution of 0.8 nm when an x-ray beam of 10(16) photons/500×500 nm(2)/pulse is available.

Measurement of impinging butane flame using combined optical system with digital speckle tomography

NASA Astrophysics Data System (ADS)

Ko, Han Seo; Ahn, Seong Soo; Kim, Hyun Jung

2011-11-01

Three-dimensional density distributions of an impinging and eccentric flame were measured experimentally using a combined optical system with digital speckle tomography. In addition, a three-dimensional temperature distribution of the flame was reconstructed from an ideal gas equation based on the reconstructed density data. The flame was formed by the ignition of premixed butane/air from air holes and impinged upward against a plate located 24 mm distance from the burner nozzle. In order to verify the reconstruction process for the experimental measurements, numerically synthesized phantoms of impinging and eccentric flames were derived and reconstructed using a developed three-dimensional multiplicative algebraic reconstruction technique (MART). A new scanning technique was developed for the accurate analysis of speckle displacements necessary for investigating the wall jet regions of the impinging flame at which a sharp variation of the flow direction and pressure gradient occur. The reconstructed temperatures by the digital speckle tomography were applied to the boundary condition for numerical analysis of a flame impinged plate. Then, the numerically calculated temperature distribution of the upper side of the flame impinged plate was compared to temperature data taken by an infrared camera. The absolute average uncertainty between the numerical and infrared camera data was 3.7%.

Process for fabricating a charge coupled device

DOEpatents

Conder, Alan D.; Young, Bruce K. F.

2002-01-01

A monolithic three dimensional charged coupled device (3D-CCD) which utilizes the entire bulk of the semiconductor for charge generation, storage, and transfer. The 3D-CCD provides a vast improvement of current CCD architectures that use only the surface of the semiconductor substrate. The 3D-CCD is capable of developing a strong E-field throughout the depth of the semiconductor by using deep (buried) parallel (bulk) electrodes in the substrate material. Using backside illumination, the 3D-CCD architecture enables a single device to image photon energies from the visible, to the ultra-violet and soft x-ray, and out to higher energy x-rays of 30 keV and beyond. The buried or bulk electrodes are electrically connected to the surface electrodes, and an E-field parallel to the surface is established with the pixel in which the bulk electrodes are located. This E-field attracts charge to the bulk electrodes independent of depth and confines it within the pixel in which it is generated. Charge diffusion is greatly reduced because the E-field is strong due to the proximity of the bulk electrodes.

Investigation of Three-Dimensional Unsteady Flow Characteristics in Transonic Diffusers

NASA Astrophysics Data System (ADS)

Proshchanka, Dzianis; Yonezawa, Koichi; Tsujimoto, Yoshinobu

Three-dimensional characteristics of unsteady flow in supercritical transonic diffuser are investigated. For various pressure ratios three-dimensional flow containing a normal shock/turbulent boundary layer interaction regions with shockwave and pseudo-shockwaves fluctuating in longitudinal and spanwise directions is observed. Experimental and numerical investigations show details of the flowfield in the vicinity of terminal shock, interaction regions and downstream turbulent unsteady flow. Spectral analysis of pressure fluctuations reveals existence of two characteristic frequencies attributed to the shockwave fluctuation in longitudinal direction for the lower frequency case and acoustic resonance in spanwise direction for the higher one. Vortices appear at each corner in transversal sections modifying the core flow. As a result, size and depth of longitudinal and vertical penetration of separation regions impelled by the terminal shock is either increased or decreased.

Mean apparent propagator (MAP) MRI: a novel diffusion imaging method for mapping tissue microstructure.

PubMed

Özarslan, Evren; Koay, Cheng Guan; Shepherd, Timothy M; Komlosh, Michal E; İrfanoğlu, M Okan; Pierpaoli, Carlo; Basser, Peter J

2013-09-01

Diffusion-weighted magnetic resonance (MR) signals reflect information about underlying tissue microstructure and cytoarchitecture. We propose a quantitative, efficient, and robust mathematical and physical framework for representing diffusion-weighted MR imaging (MRI) data obtained in "q-space," and the corresponding "mean apparent propagator (MAP)" describing molecular displacements in "r-space." We also define and map novel quantitative descriptors of diffusion that can be computed robustly using this MAP-MRI framework. We describe efficient analytical representation of the three-dimensional q-space MR signal in a series expansion of basis functions that accurately describes diffusion in many complex geometries. The lowest order term in this expansion contains a diffusion tensor that characterizes the Gaussian displacement distribution, equivalent to diffusion tensor MRI (DTI). Inclusion of higher order terms enables the reconstruction of the true average propagator whose projection onto the unit "displacement" sphere provides an orientational distribution function (ODF) that contains only the orientational dependence of the diffusion process. The representation characterizes novel features of diffusion anisotropy and the non-Gaussian character of the three-dimensional diffusion process. Other important measures this representation provides include the return-to-the-origin probability (RTOP), and its variants for diffusion in one- and two-dimensions-the return-to-the-plane probability (RTPP), and the return-to-the-axis probability (RTAP), respectively. These zero net displacement probabilities measure the mean compartment (pore) volume and cross-sectional area in distributions of isolated pores irrespective of the pore shape. MAP-MRI represents a new comprehensive framework to model the three-dimensional q-space signal and transform it into diffusion propagators. Experiments on an excised marmoset brain specimen demonstrate that MAP-MRI provides several novel, quantifiable parameters that capture previously obscured intrinsic features of nervous tissue microstructure. This should prove helpful for investigating the functional organization of normal and pathologic nervous tissue. Copyright © 2013 Elsevier Inc. All rights reserved.

Advanced miniature processing handware for ATR applications

NASA Technical Reports Server (NTRS)

Chao, Tien-Hsin (Inventor); Daud, Taher (Inventor); Thakoor, Anikumar (Inventor)

2003-01-01

A Hybrid Optoelectronic Neural Object Recognition System (HONORS), is disclosed, comprising two major building blocks: (1) an advanced grayscale optical correlator (OC) and (2) a massively parallel three-dimensional neural-processor. The optical correlator, with its inherent advantages in parallel processing and shift invariance, is used for target of interest (TOI) detection and segmentation. The three-dimensional neural-processor, with its robust neural learning capability, is used for target classification and identification. The hybrid optoelectronic neural object recognition system, with its powerful combination of optical processing and neural networks, enables real-time, large frame, automatic target recognition (ATR).

Wetting of silicone oil onto a cell-seeded substrate

NASA Astrophysics Data System (ADS)

Lu, Yongjie; Chan, Yau Kei; Chao, Youchuang; Shum, Ho Cheung

2017-11-01

Wetting behavior of solid substrates in three-phase systems containing two immiscible liquids are widely studied. There exist many three-phase systems in biological environments, such as droplet-based microfluidics or tamponade of silicone oil for eye surgery. However, few studies focus on wetting behavior of biological surfaces with cells. Here we investigate wetting of silicone oil onto cell-seeded PMMA sheet immersed in water. Using a simple parallel-plate cell, we show the effect of cell density, viscosity of silicone oil, morphology of silicone oil drops and interfacial tension on the wetting phenomenon. The dynamics of wetting is also observed by squeezing silicone oil drop using two parallel plates. Experimental results are explained based on disjoining pressure which is dependent on the interaction of biological surfaces and liquid used. These findings are useful for explaining emulsification of silicone oil in ophthalmological applications.

Multi-dimensional modeling of atmospheric copper-sulfidation corrosion on non-planar substrates.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Ken Shuang

2004-11-01

This report documents the author's efforts in the deterministic modeling of copper-sulfidation corrosion on non-planar substrates such as diodes and electrical connectors. A new framework based on Goma was developed for multi-dimensional modeling of atmospheric copper-sulfidation corrosion on non-planar substrates. In this framework, the moving sulfidation front is explicitly tracked by treating the finite-element mesh as a pseudo solid with an arbitrary Lagrangian-Eulerian formulation and repeatedly performing re-meshing using CUBIT and re-mapping using MAPVAR. Three one-dimensional studies were performed for verifying the framework in asymptotic regimes. Limited model validation was also carried out by comparing computed copper-sulfide thickness with experimentalmore » data. The framework was first demonstrated in modeling one-dimensional copper sulfidation with charge separation. It was found that both the thickness of the space-charge layers and the electrical potential at the sulfidation surface decrease rapidly as the Cu{sub 2}S layer thickens initially but eventually reach equilibrium values as Cu{sub 2}S layer becomes sufficiently thick; it was also found that electroneutrality is a reasonable approximation and that the electro-migration flux may be estimated by using the equilibrium potential difference between the sulfidation and annihilation surfaces when the Cu{sub 2}S layer is sufficiently thick. The framework was then employed to model copper sulfidation in the solid-state-diffusion controlled regime (i.e. stage II sulfidation) on a prototypical diode until a continuous Cu{sub 2}S film was formed on the diode surface. The framework was also applied to model copper sulfidation on an intermittent electrical contact between a gold-plated copper pin and gold-plated copper pad; the presence of Cu{sub 2}S was found to raise the effective electrical resistance drastically. Lastly, future research needs in modeling atmospheric copper sulfidation are discussed.« less

Experience with the Use of Prebent Plates for the Reconstruction of Mandibular Defects

PubMed Central

Salgueiro, Martin I.; Stevens, Mark R.

2010-01-01

Bending of large titanium plates for mandibular reconstruction is a tedious task. This is usually done by trial and error over an intraoperatively bent template. By means of rapid prototype technology, accurate three-dimensional models can be obtained. Using these models, it is possible to design, obtain, and adapt custom hardware for individual surgical cases. Reductions of operating room time when using this technology have been reported from 17% to 60%, with an average of 20%. This translates to reduction of cost and risks, improving the overall surgical outcome. The purpose of this article is to establish the indications and contraindication for the use three-dimensional models and prebent plates. We present our experience with five cases in which prebent reconstruction plates were used for mandibular reconstruction. No significant complications occurred, and satisfactory results were achieved in all cases. We found that the models required to obtain the hardware are extremely accurate, have multiple reported applications, and represent a valuable surgical tool in the planning and execution of reconstructive surgery. PMID:22132258

Novel 16-channel receive coil array for accelerated upper airway MRI at 3 Tesla.

PubMed

Kim, Yoon-Chul; Hayes, Cecil E; Narayanan, Shrikanth S; Nayak, Krishna S

2011-06-01

Upper airway MRI can provide a noninvasive assessment of speech and swallowing disorders and sleep apnea. Recent work has demonstrated the value of high-resolution three-dimensional imaging and dynamic two-dimensional imaging and the importance of further improvements in spatio-temporal resolution. The purpose of the study was to describe a novel 16-channel 3 Tesla receive coil that is highly sensitive to the human upper airway and investigate the performance of accelerated upper airway MRI with the coil. In three-dimensional imaging of the upper airway during static posture, 6-fold acceleration is demonstrated using parallel imaging, potentially leading to capturing a whole three-dimensional vocal tract with 1.25 mm isotropic resolution within 9 sec of sustained sound production. Midsagittal spiral parallel imaging of vocal tract dynamics during natural speech production is demonstrated with 2 × 2 mm(2) in-plane spatial and 84 ms temporal resolution. Copyright © 2010 Wiley-Liss, Inc.

Parallel processing a three-dimensional free-lagrange code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mandell, D.A.; Trease, H.E.

1989-01-01

A three-dimensional, time-dependent free-Lagrange hydrodynamics code has been multitasked and autotasked on a CRAY X-MP/416. The multitasking was done by using the Los Alamos Multitasking Control Library, which is a superset of the CRAY multitasking library. Autotasking is done by using constructs which are only comment cards if the source code is not run through a preprocessor. The three-dimensional algorithm has presented a number of problems that simpler algorithms, such as those for one-dimensional hydrodynamics, did not exhibit. Problems in converting the serial code, originally written for a CRAY-1, to a multitasking code are discussed. Autotasking of a rewritten versionmore » of the code is discussed. Timing results for subroutines and hot spots in the serial code are presented and suggestions for additional tools and debugging aids are given. Theoretical speedup results obtained from Amdahl's law and actual speedup results obtained on a dedicated machine are presented. Suggestions for designing large parallel codes are given.« less

Three-dimensional charge transport in organic semiconductor single crystals.

PubMed

He, Tao; Zhang, Xiying; Jia, Jiong; Li, Yexin; Tao, Xutang

2012-04-24

Three-dimensional charge transport anisotropy in organic semiconductor single crystals - both plates and rods (above and below, respectively, in the figure) - is measured in well-performing organic field-effect transistors for the first time. The results provide an excellent model for molecular design and device preparation that leads to good performance. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Gibbs point field model for the spatial pattern of coronary capillaries

NASA Astrophysics Data System (ADS)

Karch, R.; Neumann, M.; Neumann, F.; Ullrich, R.; Neumüller, J.; Schreiner, W.

2006-09-01

We propose a Gibbs point field model for the pattern of coronary capillaries in transverse histologic sections from human hearts, based on the physiology of oxygen supply from capillaries to tissue. To specify the potential energy function of the Gibbs point field, we draw on an analogy between the equation of steady-state oxygen diffusion from an array of parallel capillaries to the surrounding tissue and Poisson's equation for the electrostatic potential of a two-dimensional distribution of identical point charges. The influence of factors other than diffusion is treated as a thermal disturbance. On this basis, we arrive at the well-known two-dimensional one-component plasma, a system of identical point charges exhibiting a weak (logarithmic) repulsive interaction that is completely characterized by a single dimensionless parameter. By variation of this parameter, the model is able to reproduce many characteristics of real capillary patterns.

Heat exchange apparatus

DOEpatents

Degtiarenko, Pavel V.

2003-08-12

A heat exchange apparatus comprising a coolant conduit or heat sink having attached to its surface a first radial array of spaced-apart parallel plate fins or needles and a second radial array of spaced-apart parallel plate fins or needles thermally coupled to a body to be cooled and meshed with, but not contacting the first radial array of spaced-apart parallel plate fins or needles.

Two-dimensional dynamics of elasto-inertial turbulence and its role in polymer drag reduction

NASA Astrophysics Data System (ADS)

Sid, S.; Terrapon, V. E.; Dubief, Y.

2018-02-01

The goal of the present study is threefold: (i) to demonstrate the two-dimensional nature of the elasto-inertial instability in elasto-inertial turbulence (EIT), (ii) to identify the role of the bidimensional instability in three-dimensional EIT flows, and (iii) to establish the role of the small elastic scales in the mechanism of self-sustained EIT. Direct numerical simulations of viscoelastic fluid flows are performed in both two- and three-dimensional straight periodic channels using the Peterlin finitely extensible nonlinear elastic model (FENE-P). The Reynolds number is set to Reτ=85 , which is subcritical for two-dimensional flows but beyond the transition for three-dimensional ones. The polymer properties selected correspond to those of typical dilute polymer solutions, and two moderate Weissenberg numbers, Wiτ=40 ,100 , are considered. The simulation results show that sustained turbulence can be observed in two-dimensional subcritical flows, confirming the existence of a bidimensional elasto-inertial instability. The same type of instability is also observed in three-dimensional simulations where both Newtonian and elasto-inertial turbulent structures coexist. Depending on the Wi number, one type of structure can dominate and drive the flow. For large Wi values, the elasto-inertial instability tends to prevail over the Newtonian turbulence. This statement is supported by (i) the absence of typical Newtonian near-wall vortices and (ii) strong similarities between two- and three-dimensional flows when considering larger Wi numbers. The role of small elastic scales is investigated by introducing global artificial diffusion (GAD) in the hyperbolic transport equation for polymers. The aim is to measure how the flow reacts when the smallest elastic scales are progressively filtered out. The study results show that the introduction of large polymer diffusion in the system strongly damps a significant part of the elastic scales that are necessary to feed turbulence, eventually leading to flow laminarization. A sufficiently high Schmidt number (weakly diffusive polymers) is necessary to allow self-sustained turbulence to settle. Although EIT can withstand a low amount of diffusion and remains in a nonlaminar chaotic state, adding a finite amount of GAD in the system can have an impact on the dynamics and lead to important quantitative changes, even for Schmidt numbers as large as 102. The use of GAD should therefore be avoided in viscoelastic flow simulations.

Omnidirectional-view three-dimensional display system based on cylindrical selective-diffusing screen.

PubMed

Xia, Xinxing; Zheng, Zhenrong; Liu, Xu; Li, Haifeng; Yan, Caijie

2010-09-10

We utilized a high-frame-rate projector, a rotating mirror, and a cylindrical selective-diffusing screen to present a novel three-dimensional (3D) omnidirectional-view display system without the need for any special viewing aids. The display principle and image size are analyzed, and the common display zone is proposed. The viewing zone for one observation place is also studied. The experimental results verify this method, and a vivid color 3D scene with occlusion and smooth parallax is also demonstrated with the system.

Three-dimensional MR imaging in the assessment of physeal growth arrest.

PubMed

Sailhan, Frédéric; Chotel, Franck; Guibal, Anne-Laure; Gollogly, Sohrab; Adam, Philippe; Bérard, Jérome; Guibaud, Laurent

2004-09-01

The purpose of this study is to describe an imaging method for identifying and characterising physeal growth arrest following physeal plate aggression. The authors describe the use of three-dimensional MRI performed with fat-suppressed three-dimensional spoiled gradient-recalled echo sequences followed by manual image reconstruction to create a 3D model of the physeal plate. This retrospective series reports the analysis of 33 bony physeal bridges in 28 children (mean age 10.5 years) with the use of fat-suppressed three-dimensional spoiled gradient-recalled echo imaging and 3D reconstructions from the source images. 3D reconstructions were obtained after the outlining was done manually on each source image. Files of all patients were reviewed for clinical data at the time of MRI, type of injury, age at MRI and bone bridge characteristics on reconstructions. Twenty-one (63%) of the 33 bridges were post-traumatic and were mostly situated in the lower extremities (19/21). The distal tibia was involved in 66% (14/21) of the cases. Bridges due to causes other than trauma were located in the lower extremities in 10/12 cases, and the distal femur represented 60% of these cases. Of the 28 patients, five presented with two bridges involving two different growth plates making a total of 33 physeal bone bars. The location and shape of each bridge was accurately identified in each patient, and in post-traumatic cases, 89% of bone bars were of Ogden type III (central) or I (peripheral). Reconstructions were obtained in 15 min and are easy to interpret. Volumes of the physeal bone bridge(s) and of the remaining normal physis were calculated. The bone bridging represented less than 1% to 47% of the total physeal plate volume. The precise shape and location of the bridge can be visualised on the 3D reconstructions. This information is useful in the surgical management of these deformities; as for the eight patients who underwent bone bar resection, an excellent correspondence was found by the treating surgeon between the MRI 3D model and the per-operative findings. Accurate 3D mapping obtained after manual reconstruction can also visualise very small physeal plates and bridges such as in cases of finger physeal disorders. MR imaging with fat-suppressed three-dimensional spoiled gradient-recalled echo sequences can be used to identify patterns of physeal growth arrest. 3D reconstructions can be obtained from the manual outlining of source images to provide an accurate representation of the bony bridge that can be a guide during surgical management.

X-ray evaluation of SEM technique for determining the crystallography of echinoid skeletons.

PubMed

Dillaman, R M; Hart, H V

1981-01-01

Coronal plates of the sea urchin Strongylocentrotus purpuratus have a microstructure typified by smooth textured trabeculae. When plates were decorated with calcite crystals each rhombohedron had the same orientation regardless of its location on the plate. When the sample was oriented so that the three edges of the rhombohedron formed equal 120 degrees angles and the three crystal faces appeared to form equal angles with the plane of the photograph, the c-axis of the plate paralleled the electron beam and the three a-axes were 30 degrees counterclockwise from the edges. These a-axes were then related to a plate edge recorded in a low magnification micrograph. Directions of the a-axes of each plate were also measured using a back-reflection Laue x-ray diffraction camera. A comparison of a-axes measured by the two techniques showed an average difference of 3 degrees, indicating that decorated crystal grew in crystallographic continuity with the plate. Assuming this relationship remains constant, the decoration technique appears to be an accurate and efficient method for evaluating the crystallography of echinoid skeletal units. Analysis of a polar plot of a-axes for 11 plates indicated that the a-axes were not randomly oriented; however, definitive relationships must await more extensive investigations.

Three-dimensional finite element analysis of occipitocervical fixation using an anterior occiput-to-axis locking plate system: a pilot study.

PubMed

Cai, Xianhua; Yu, Yang; Liu, Zhichao; Zhang, Meichao; Huang, Weibing

2014-08-01

Although there are many techniques for occipitocervical fixation, there have been no reports regarding occipitocervical fixation via the use of an anterior anatomical locking plate system. The biomechanics of this new system were analyzed by a three-dimensional finite element to provide a theoretical basis for clinical application. This was a modeling study. We studied a 27-year-old healthy male volunteer in whom cervical disease was excluded via X-ray examination. The states of stress and strain of these two internal fixation devices were analyzed. A three-dimensional finite element model of normal occiput-C2 was established based on the anatomical data from a Chinese population. An unstable model of occipital-cervical region was established by subtracting several unit structures from the normal model. An anterior occiput-to-axis locking titanium plate system was then applied and an anterior occiput-to-axis screw fixation was performed on the unstable model. Limitation of motion was performed on the surface of the fixed model, and physiological loads were imposed on the surface of the skull base. Under various loads from different directions, the peak values of displacement of the anterior occiput-to-axis locking titanium plate system decreased 15.5%, 12.5%, 14.4%, and 23.7%, respectively, under the loads of flexion, extension, lateral bending, and axial rotation. Compared with the anterior occiput-to-axis screw fixation, the peak values of stress of the anterior occiput-to-axis locking titanium plate system also decreased 3.9%, 2.9%, 9.7%, and 7.2%, respectively, under the loads of flexion, extension, lateral bending, and axial rotation. The anterior occiput-to-axis locking titanium plate system proved superior to the anterior occiput-to-axis screw system both in the stress distribution and fixation stability based on finite element analysis. It provides a new clinical option for anterior occipitocervical fixation. Copyright © 2014 Elsevier Inc. All rights reserved.

Characterizing the adhesion of motile and nonmotile Escherichia coli to a glass surface using a parallel-plate flow chamber.

PubMed

McClaine, Jennifer W; Ford, Roseanne M

2002-04-20

A parallel-plate flow chamber was used to measure the attachment and detachment rates of Escherichia coli to a glass surface at various fluid velocities. The effect of flagella on adhesion was investigated by performing experiments with several E. coli strains: AW405 (motile); HCB136 (nonmotile mutant with paralyzed flagella); and HCB137 (nonmotile mutant without flagella). We compared the total attachment rates and the fraction of bacteria retained on the surface to determine how the presence and movement of the flagella influence transport to the surface and adhesion strength in this dynamic system. At the lower fluid velocities, there was no significant difference in the total attachment rates for the three bacterial strains; nonmotile strains settled at a rate that was of the same order of magnitude as the diffusion rate of the motile strain. At the highest fluid velocity, the effect of settling was minimized to better illustrate the importance of motility, and the attachment rates of both nonmotile strains were approximately five times slower than that of the motile bacteria. Thus, different processes controlled the attachment rate depending on the parameter regime in which the experiment was performed. The fractions of motile bacteria retained on the glass surface increased with increasing velocity, whereas the opposite trend was found for the nonmotile strains. This suggests that the rotation of the flagella enables cells to detach from the surface (at the lower fluid velocities) and strengthens adhesion (at higher fluid velocities), whereas nonmotile cells detach as a result of shear. There was no significant difference in the initial attachment rates of the two nonmotile species, which suggests that merely the presence of flagella was not important in this stage of biofilm development. Copyright 2002 Wiley Periodicals, Inc.

Multitasking the three-dimensional transport code TORT on CRAY platforms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azmy, Y.Y.; Barnett, D.A.; Burre, C.A.

1996-04-01

The multitasking options in the three-dimensional neutral particle transport code TORT originally implemented for Cray`s CTSS operating system are revived and extended to run on Cray Y/MP and C90 computers using the UNICOS operating system. These include two coarse-grained domain decompositions; across octants, and across directions within an octant, termed Octant Parallel (OP), and Direction Parallel (DP), respectively. Parallel performance of the DP is significantly enhanced by increasing the task grain size and reducing load imbalance via dynamic scheduling of the discrete angles among the participating tasks. Substantial Wall Clock speedup factors, approaching 4.5 using 8 tasks, have been measuredmore » in a time-sharing environment, and generally depend on the test problem specifications, number of tasks, and machine loading during execution.« less

Three-dimensional vectorial multifocal arrays created by pseudo-period encoding

NASA Astrophysics Data System (ADS)

Zeng, Tingting; Chang, Chenliang; Chen, Zhaozhong; Wang, Hui-Tian; Ding, Jianping

2018-06-01

Multifocal arrays have been attracting considerable attention recently owing to their potential applications in parallel optical tweezers, parallel single-molecule orientation determination, parallel recording and multifocal multiphoton microscopy. However, the generation of vectorial multifocal arrays with a tailorable structure and polarization state remains a great challenge, and reports on multifocal arrays have hitherto been restricted either to scalar focal spots without polarization versatility or to regular arrays with fixed spacing. In this work, we propose a specific pseudo-period encoding technique to create three-dimensional (3D) vectorial multifocal arrays with the ability to manipulate the position, polarization state and intensity of each focal spot. We experimentally validated the flexibility of our approach in the generation of 3D vectorial multiple spots with polarization multiplicity and position tunability.

MULTI-SPACECRAFT OBSERVATIONS AND TRANSPORT MODELING OF ENERGETIC ELECTRONS FOR A SERIES OF SOLAR PARTICLE EVENTS IN AUGUST 2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dröge, W.; Kartavykh, Y. Y.; Dresing, N.

During 2010 August a series of solar particle events was observed by the two STEREO spacecraft as well as near-Earth spacecraft. The events, occurring on August 7, 14, and 18, originated from active regions 11093 and 11099. We combine in situ and remote-sensing observations with predictions from our model of three-dimensional anisotropic particle propagation in order to investigate the physical processes that caused the large angular spreads of energetic electrons during these events. In particular, we address the effects of the lateral transport of the electrons in the solar corona that is due to diffusion perpendicular to the average magneticmore » field in the interplanetary medium. We also study the influence of two coronal mass ejections and associated shock waves on the electron propagation, and a possible time variation of the transport conditions during the above period. For the August 18 event we also utilize electron observations from the MESSENGER spacecraft at a distance of 0.31 au from the Sun for an attempt to separate between radial and longitudinal dependencies in the transport process. Our modelings show that the parallel and perpendicular diffusion mean free paths of electrons can vary significantly not only as a function of the radial distance, but also of the heliospheric longitude. Normalized to a distance of 1 au, we derive values of λ {sub ∥} in the range of 0.15–0.6 au, and values of λ {sub ⊥} in the range of 0.005–0.01 au. We discuss how our results relate to various theoretical models for perpendicular diffusion, and whether there might be a functional relationship between the perpendicular and the parallel mean free path.« less

Multi-spacecraft Observations and Transport Modeling of Energetic Electrons for a Series of Solar Particle Events in August 2010

NASA Astrophysics Data System (ADS)

Dröge, W.; Kartavykh, Y. Y.; Dresing, N.; Klassen, A.

2016-08-01

During 2010 August a series of solar particle events was observed by the two STEREO spacecraft as well as near-Earth spacecraft. The events, occurring on August 7, 14, and 18, originated from active regions 11093 and 11099. We combine in situ and remote-sensing observations with predictions from our model of three-dimensional anisotropic particle propagation in order to investigate the physical processes that caused the large angular spreads of energetic electrons during these events. In particular, we address the effects of the lateral transport of the electrons in the solar corona that is due to diffusion perpendicular to the average magnetic field in the interplanetary medium. We also study the influence of two coronal mass ejections and associated shock waves on the electron propagation, and a possible time variation of the transport conditions during the above period. For the August 18 event we also utilize electron observations from the MESSENGER spacecraft at a distance of 0.31 au from the Sun for an attempt to separate between radial and longitudinal dependencies in the transport process. Our modelings show that the parallel and perpendicular diffusion mean free paths of electrons can vary significantly not only as a function of the radial distance, but also of the heliospheric longitude. Normalized to a distance of 1 au, we derive values of λ ∥ in the range of 0.15-0.6 au, and values of λ ⊥ in the range of 0.005-0.01 au. We discuss how our results relate to various theoretical models for perpendicular diffusion, and whether there might be a functional relationship between the perpendicular and the parallel mean free path.

2-D to 3-D global/local finite element analysis of cross-ply composite laminates

NASA Technical Reports Server (NTRS)

Thompson, D. Muheim; Griffin, O. Hayden, Jr.

1990-01-01

An example of two-dimensional to three-dimensional global/local finite element analysis of a laminated composite plate with a hole is presented. The 'zoom' technique of global/local analysis is used, where displacements of the global/local interface from the two-dimensional global model are applied to the edges of the three-dimensional local model. Three different hole diameters, one, three, and six inches, are considered in order to compare the effect of hole size on the three-dimensional stress state around the hole. In addition, three different stacking sequences are analyzed for the six inch hole case in order to study the effect of stacking sequence. The existence of a 'critical' hole size, where the interlaminar stresses are maximum, is indicated. Dispersion of plies at the same angle, as opposed to clustering, is found to reduce the magnitude of some interlaminar stress components and increase others.

Parallel flow diffusion battery

DOEpatents

Yeh, H.C.; Cheng, Y.S.

1984-01-01

A parallel flow diffusion battery for determining the mass distribution of an aerosol has a plurality of diffusion cells mounted in parallel to an aerosol stream, each diffusion cell including a stack of mesh wire screens of different density.

Parallel flow diffusion battery

DOEpatents

Yeh, Hsu-Chi; Cheng, Yung-Sung

1984-08-07

A parallel flow diffusion battery for determining the mass distribution of an aerosol has a plurality of diffusion cells mounted in parallel to an aerosol stream, each diffusion cell including a stack of mesh wire screens of different density.

The formation of thermohaline staircases for large salt concentration differences in double diffusive convection

NASA Astrophysics Data System (ADS)

Yang, Yantao; Verzicco, Roberto; Lohse, Detlef

2016-11-01

In the upper layers of the tropical and subtropical ocean, step-like mean profiles for both temperature and salinity are often observed, a phenomenon referred to as thermohaline staircase. It consists of alternatively stacked mixing layers, and finger layers with sharp gradients in both mean temperature and salinity. It is believed that thermohaline staircases are caused by double diffusive convection (DDC), i.e. the convection flow with fluid density affected by two different scalars. Here we conducted direct numerical simulations of DDC bounded by two parallel plates and aimed to realise the multi-layer state similar to the oceanic thermohaline staircase. We applied an unstable salinity difference and a stable temperature difference across the two plates. We gradually increased the salinity Rayleigh number RaS , i.e. the strength of salinity difference, and fixed the relative strength of temperature difference. When RaS is high enough the flow undergoes a transition from a single finger layer to a triple layer state, where one mixing layer emerges between two finger layers. Such triple layer state is stable up to the turbulent diffusive time scale. The finger-layer height is larger for higher RaS . The dependences of the scalar fluxes on RaS were also investigated. Supported by Dutch FOM Foundation and NWO rpogramme MCEC; Computing resources from SURFSara and PRACE project 2015133124.

An Interdisciplinary Theme: Topographic Maps and Plate Tectonics

ERIC Educational Resources Information Center

Concannon, James P.; Aulgur, Linda

2011-01-01

This is an interdisciplinary lesson designed for middle school students studying landforms and geological processes. Students create a two-dimensional topographic map from a three-dimensional landform that they create using clay. Students then use other groups' topographic maps to re-create landforms. Following this, students explore some basic…

Self-propulsion of Leidenfrost Drops between Non-Parallel Structures.

PubMed

Luo, Cheng; Mrinal, Manjarik; Wang, Xiang

2017-09-20

In this work, we explored self-propulsion of a Leidenfrost drop between non-parallel structures. A theoretical model was first developed to determine conditions for liquid drops to start moving away from the corner of two non-parallel plates. These conditions were then simplified for the case of a Leidenfrost drop. Furthermore, ejection speeds and travel distances of Leidenfrost drops were derived using a scaling law. Subsequently, the theoretical models were validated by experiments. Finally, three new devices have been developed to manipulate Leidenfrost drops in different ways.

Reduced-thickness backlighter for autostereoscopic display and display using the backlighter

NASA Technical Reports Server (NTRS)

Eichenlaub, Jesse B (Inventor); Gruhlke, Russell W (Inventor)

1999-01-01

A reduced-thickness backlighter for an autostereoscopic display is disclosed having a lightguide and at least one light source parallel to an edge of the lightguide so as to be substantially coplanar with the lightguide. The lightguide is provided with a first surface which has a plurality of reflective linear regions, such as elongated grooves or glossy lines, parallel to the illuminated edge of the lightguide. Preferably the lightguide further has a second surface which has a plurality of lenticular lenses for reimaging the reflected light from the linear regions into a series of thin vertical lines outside the guide. Because of the reduced thickness of the backlighter system, autostereoscopic viewing is enabled in applications requiring thin backlighter systems. In addition to taking up less space, the reduced-thickness backlighter uses less lamps and less power. For accommodating 2-D applications, a 2-D diffuser plate or a 2-D lightguide parallel to the 3-D backlighter is disclosed for switching back and forth between 3-D viewing and 2-D viewing.

A calibration mechanism based on worm drive for space telescope

NASA Astrophysics Data System (ADS)

Chong, Yaqin; Li, Chuang; Xia, Siyu; Zhong, Peifeng; Lei, Wang

2017-08-01

In this paper, a new type of calibration mechanism based on worm drive is presented for a space telescope. This calibration mechanism based on worm drive has the advantages of compact size and self-lock. The mechanism mainly consists of thirty-six LEDs as the light source for flat calibration, a diffuse plate, a step motor, a worm gear reducer and a potentiometer. As the main part of the diffuse plate, a PTFE tablet is mounted in an aluminum alloy frame. The frame is fixed on the shaft of the worm gear, which is driven by the step motor through the worm. The shaft of the potentiometer is connected to that of the worm gear to measure the rotation angle of the diffuse plate through a flexible coupler. Firstly, the calibration mechanism is designed, which includes the LEDs assembly design, the worm gear reducer design and the diffuse plate assembly design. The counterweight blocks and two end stops are also designed for the diffuse plate assembly. Then a modal analysis with finite element method for the diffuse plate assembly is completed.

Multigrid finite element method in stress analysis of three-dimensional elastic bodies of heterogeneous structure

NASA Astrophysics Data System (ADS)

Matveev, A. D.

2016-11-01

To calculate the three-dimensional elastic body of heterogeneous structure under static loading, a method of multigrid finite element is provided, when implemented on the basis of algorithms of finite element method (FEM), using homogeneous and composite threedimensional multigrid finite elements (MFE). Peculiarities and differences of MFE from the currently available finite elements (FE) are to develop composite MFE (without increasing their dimensions), arbitrarily small basic partition of composite solids consisting of single-grid homogeneous FE of the first order can be used, i.e. in fact, to use micro approach in finite element form. These small partitions allow one to take into account in MFE, i.e. in the basic discrete models of composite solids, complex heterogeneous and microscopically inhomogeneous structure, shape, the complex nature of the loading and fixation and describe arbitrarily closely the stress and stain state by the equations of three-dimensional elastic theory without any additional simplifying hypotheses. When building the m grid FE, m of nested grids is used. The fine grid is generated by a basic partition of MFE, the other m —1 large grids are applied to reduce MFE dimensionality, when m is increased, MFE dimensionality becomes smaller. The procedures of developing MFE of rectangular parallelepiped, irregular shape, plate and beam types are given. MFE generate the small dimensional discrete models and numerical solutions with a high accuracy. An example of calculating the laminated plate, using three-dimensional 3-grid FE and the reference discrete model is given, with that having 2.2 milliards of FEM nodal unknowns.

Galaxy interactions and star formation: Results of a survey of global H-alpha emission in spiral galaxies in 8 clusters

NASA Technical Reports Server (NTRS)

Moss, C.

1990-01-01

Kennicutt and Kent (1983) have shown that the global H alpha emission from a spiral galaxy is an indicator of the formation rate of massive stars. Moss, Whittle and Irwin (1988) have surveyed two clusters (Abell 347 and 1367) for galaxies with H alpha emission using a high dispersion objective prism technique. The purpose of the survey is to investigate environmental effects on star formation in spiral galaxies, and in particular to ascertain whether star formation is enhanced in cluster spirals. Approximately 20 percent of CGCG galaxies were detected in emission. Two plates of excellent quality were obtained for each of the two clusters, and galaxies were only identified to have emission if this was detected on both plates of a plate pair. In this way, plate flaws and other spurious identifications of emission could be rejected, and weak emission confirmed. The results of this survey have been discussed by Moss (1987). The detected galaxies are of types SO-a and later. The frequency with which galaxies are detected in emission increases towards later morphological type as expected (cf. Kennicutt and Kent 1983). There is no evidence of any dependence of the frequency of detected emission on the absolute magnitude of the galaxy (cf. Moss and Whittle 1990), but there is a strong correlation between a disturbed morphological appearance of the galaxy and the detection of emission. Furthermore it is found that the emission is more centrally concentrated in those galaxies which show a disturbed morphology. It may be noted that the objective prism plate gives a spectrum of a 400 A region around rest wavelength H alpha, but superposed on this is the H alpha emission from the galaxy which, because the light is essentially monochromatic, results in a true two-dimensional image of the H alpha distribution. The visual appearance of the emission on the prism plates was classified according to its diffuseness on a 5 point scale (very diffuse, diffuse, intermediate, compact, and very compact). In tabular form, the relation is shown between this classification and a morphologically disturbed appearance for the galaxy.

Analysis of Delamination Growth from Matrix Cracks in Laminates Subjected to Bending Loads

NASA Technical Reports Server (NTRS)

Murri, G. B.; Guynn, E. G.

1986-01-01

A major source of delamination damage in laminated composite materials is from low-velocity impact. In thin composite laminates under point loads, matrix cracks develop first in the plies, and delaminations then grow from these cracks at the ply interfaces. The purpose of this study was to quantify the combined effects of bending and transverse shear loads on delamination initiation from matrix cracks. Graphite-epoxy laminates with 90 deg. plies on the outside were used to provide a two-dimensional simulation of the damage due to low-velocity impact. Three plate bending problems were considered: a 4-point bending, 3-point bending, and an end-clamped center-loaded plate. Under bending, a matrix crack will form on the tension side of the laminate, through the outer 90 deg. plies and parallel to the fibers. Delaminations will then grow in the interface between the cracked 90 deg. ply and the next adjacent ply. Laminate plate theory was used to derive simple equations relating the total strain energy release rate, G, associated with the delamination growth from a 90 deg. ply crack to the applied bending load and laminate stiffness properties. Three different lay-ups were tested and results compared. Test results verified that the delamination always formed at the interface between the cracked 90 deg. ply and the next adjacent ply. Calculated values for total G sub c from the analysis showed good agreement for all configurations. The analysis was able to predict the delamination onset load for the cases considered. The result indicated that the opening mode component (Mode I) for delamination growth from a matrix crack may be much larger than the component due to interlaminar shear (Mode II).

Computer-generated 3D ultrasound images of the carotid artery

NASA Technical Reports Server (NTRS)

Selzer, Robert H.; Lee, Paul L.; Lai, June Y.; Frieden, Howard J.; Blankenhorn, David H.

1989-01-01

A method is under development to measure carotid artery lesions from a computer-generated three-dimensional ultrasound image. For each image, the position of the transducer in six coordinates (x, y, z, azimuth, elevation, and roll) is recorded and used to position each B-mode picture element in its proper spatial position in a three-dimensional memory array. After all B-mode images have been assembled in the memory, the three-dimensional image is filtered and resampled to produce a new series of parallel-plane two-dimensional images from which arterial boundaries are determined using edge tracking methods.

Computer-generated 3D ultrasound images of the carotid artery

NASA Astrophysics Data System (ADS)

Selzer, Robert H.; Lee, Paul L.; Lai, June Y.; Frieden, Howard J.; Blankenhorn, David H.

A method is under development to measure carotid artery lesions from a computer-generated three-dimensional ultrasound image. For each image, the position of the transducer in six coordinates (x, y, z, azimuth, elevation, and roll) is recorded and used to position each B-mode picture element in its proper spatial position in a three-dimensional memory array. After all B-mode images have been assembled in the memory, the three-dimensional image is filtered and resampled to produce a new series of parallel-plane two-dimensional images from which arterial boundaries are determined using edge tracking methods.

A three-dimensional spin-diffusion model for micromagnetics

PubMed Central

Abert, Claas; Ruggeri, Michele; Bruckner, Florian; Vogler, Christoph; Hrkac, Gino; Praetorius, Dirk; Suess, Dieter

2015-01-01

We solve a time-dependent three-dimensional spin-diffusion model coupled to the Landau-Lifshitz-Gilbert equation numerically. The presented model is validated by comparison to two established spin-torque models: The model of Slonzewski that describes spin-torque in multi-layer structures in the presence of a fixed layer and the model of Zhang and Li that describes current driven domain-wall motion. It is shown that both models are incorporated by the spin-diffusion description, i.e., the nonlocal effects of the Slonzewski model are captured as well as the spin-accumulation due to magnetization gradients as described by the model of Zhang and Li. Moreover, the presented method is able to resolve the time dependency of the spin-accumulation. PMID:26442796

High-fidelity meshes from tissue samples for diffusion MRI simulations.

PubMed

Panagiotaki, Eleftheria; Hall, Matt G; Zhang, Hui; Siow, Bernard; Lythgoe, Mark F; Alexander, Daniel C

2010-01-01

This paper presents a method for constructing detailed geometric models of tissue microstructure for synthesizing realistic diffusion MRI data. We construct three-dimensional mesh models from confocal microscopy image stacks using the marching cubes algorithm. Random-walk simulations within the resulting meshes provide synthetic diffusion MRI measurements. Experiments optimise simulation parameters and complexity of the meshes to achieve accuracy and reproducibility while minimizing computation time. Finally we assess the quality of the synthesized data from the mesh models by comparison with scanner data as well as synthetic data from simple geometric models and simplified meshes that vary only in two dimensions. The results support the extra complexity of the three-dimensional mesh compared to simpler models although sensitivity to the mesh resolution is quite robust.

Failed oceanic transform models: experience of shaking the tree

NASA Astrophysics Data System (ADS)

Gerya, Taras

2017-04-01

In geodynamics, numerical modeling is often used as a trial-and-error tool, which does not necessarily requires full understanding or even a correct concept for a modeled phenomenon. Paradoxically, in order to understand an enigmatic process one should simply try to model it based on some initial assumptions, which must not even be correct… The reason is that our intuition is not always well "calibrated" for understanding of geodynamic phenomena, which develop on space- and timescales that are very different from our everyday experience. We often have much better ideas about physical laws governing geodynamic processes than on how these laws should interact on geological space- and timescales. From this prospective, numerical models, in which these physical laws are self-consistently implemented, can gradually calibrate our intuition by exploring what scenarios are physically sensible and what are not. I personally went through this painful learning path many times and one noteworthy example was my 3D numerical modeling of oceanic transform faults. As I understand in retrospective, my initial literature-inspired concept of how and why transform faults form and evolve was thermomechanically inconsistent and based on two main assumptions (btw. both were incorrect!): (1) oceanic transforms are directly inherited from the continental rifting and breakup stages and (2) they represent plate fragmentation structures having peculiar extension-parallel orientation due to the stress rotation caused by thermal contraction of the oceanic lithosphere. During one year (!) of high-resolution thermomechanical numerical experiments exploring various physics (including very computationally demanding thermal contraction) I systematically observed how my initially prescribed extension-parallel weak transform faults connecting ridge segments rotated away from their original orientation and get converted into oblique ridge sections… This was really an epic failure! However, at the very same time, some pseudo-2D "side-models" with initial strait ridge and ad-hock strain weakened rheology, which were run for curiosity, suddenly showed spontaneous development of ridge curvature… Fraction of these models showed spontaneous development of orthogonal ridge-transform patterns by rotation of oblique ridge sections toward extension-parallel direction to accommodate asymmetric plate accretion. The later was controlled by detachment faults stabilized by strain weakening. Further exploration of these "side-models" resulted in complete changing of my concept for oceanic transforms: they are not plate fragmentation but rather plate growth structures stabilized by continuous plate accretion and rheological weakening of deforming rocks (Gerya, 2010, 2013). The conclusion is - keep shaking the tree and banana will fall… Gerya, T. (2010) Dynamical instability produces transform faults at mid-ocean ridges. Science, 329, 1047-1050. Gerya, T.V. (2013) Three-dimensional thermomechanical modeling of oceanic spreading initiation and evolution. Phys. Earth Planet. Interiors, 214, 35-52.

Posttest analysis of a 1:6-scale reinforced concrete reactor containment building

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weatherby, J.R.

In an experiment conducted at Sandia National Laboratories, 1:6-scale model of a reinforced concrete light water reactor containment building was pressurized with nitrogen gas to more than three times its design pressure. The pressurization produced one large tear and several smaller tears in the steel liner plate that functioned as the primary pneumatic seal for the structure. The data collected from the overpressurization test have been used to evaluate and further refine methods of structural analysis that can be used to predict the performance of containment buildings under conditions produced by a severe accident. This report describes posttest finite elementmore » analyses of the 1:6-scale model tests and compares pretest predictions of the structural response to the experimental results. Strain and displacements calculated in axisymmetric finite element analyses of the 1:6-scale model are compared to strains and displacement measured in the experiment. Detailed analyses of the liner plate are also described in the report. The region of the liner surrounding the large tear was analyzed using two different two-dimensional finite elements model. The results from these analyzed indicate that the primary mechanisms that initiated the tear can be captured in a two- dimensional finite element model. Furthermore, the analyses show that studs used to anchor the liner to the concrete wall, played an important role in initiating the liner tear. Three-dimensional finite element analyses of liner plates loaded by studs are also presented. Results from the three-dimensional analyses are compared to results from two-dimensional analyses of the same problems. 12 refs., 56 figs., 1 tab.« less

Determination of the Fracture Parameters in a Stiffened Composite Panel

NASA Technical Reports Server (NTRS)

Lin, Chung-Yi

2000-01-01

A modified J-integral, namely the equivalent domain integral, is derived for a three-dimensional anisotropic cracked solid to evaluate the stress intensity factor along the crack front using the finite element method. Based on the equivalent domain integral method with auxiliary fields, an interaction integral is also derived to extract the second fracture parameter, the T-stress, from the finite element results. The auxiliary fields are the two-dimensional plane strain solutions of monoclinic materials with the plane of symmetry at x(sub 3) = 0 under point loads applied at the crack tip. These solutions are expressed in a compact form based on the Stroh formalism. Both integrals can be implemented into a single numerical procedure to determine the distributions of stress intensity factor and T-stress components, T11, T13, and thus T33, along a three-dimensional crack front. The effects of plate thickness and crack length on the variation of the stress intensity factor and T-stresses through the thickness are investigated in detail for through-thickness center-cracked plates (isotropic and orthotropic) and orthotropic stiffened panels under pure mode-I loading conditions. For all the cases studied, T11 remains negative. For plates with the same dimensions, a larger size of crack yields larger magnitude of the normalized stress intensity factor and normalized T-stresses. The results in orthotropic stiffened panels exhibit an opposite trend in general. As expected, for the thicker panels, the fracture parameters evaluated through the thickness, except the region near the free surfaces, approach two-dimensional plane strain solutions. In summary, the numerical methods presented in this research demonstrate their high computational effectiveness and good numerical accuracy in extracting these fracture parameters from the finite element results in three-dimensional cracked solids.

SERODS optical data storage with parallel signal transfer

DOEpatents

Vo-Dinh, Tuan

2003-09-02

Surface-enhanced Raman optical data storage (SERODS) systems having increased reading and writing speeds, that is, increased data transfer rates, are disclosed. In the various SERODS read and write systems, the surface-enhanced Raman scattering (SERS) data is written and read using a two-dimensional process called parallel signal transfer (PST). The various embodiments utilize laser light beam excitation of the SERODS medium, optical filtering, beam imaging, and two-dimensional light detection. Two- and three-dimensional SERODS media are utilized. The SERODS write systems employ either a different laser or a different level of laser power.

SERODS optical data storage with parallel signal transfer

DOEpatents

Vo-Dinh, Tuan

2003-06-24

Surface-enhanced Raman optical data storage (SERODS) systems having increased reading and writing speeds, that is, increased data transfer rates, are disclosed. In the various SERODS read and write systems, the surface-enhanced Raman scattering (SERS) data is written and read using a two-dimensional process called parallel signal transfer (PST). The various embodiments utilize laser light beam excitation of the SERODS medium, optical filtering, beam imaging, and two-dimensional light detection. Two- and three-dimensional SERODS media are utilized. The SERODS write systems employ either a different laser or a different level of laser power.

MARGINS mini-lessons: A tour of the Mariana Subduction System (Invited)

NASA Astrophysics Data System (ADS)

Goodliffe, A. M.; Oakley, A.

2009-12-01

MARGINS mini-lessons provide an efficient way to quickly move cutting edge MARGINS research into the university classroom. Instructors who are not necessarily familiar with the MARGINS program can easily use mini-lessons in a variety of educational settings. The mini-lesson described herein is centered on bathymetric and multi-channel seismic data collected during a 2003 NSF-MARGINS funded marine geophysical survey in the Mariana Basin. Designed as an approximately sixty minute lecture segment, the lesson covers both the techniques used to collect marine geophysical data and a description of the geology of the system. All geological provinces are included, from the subducting Pacific Plate in the east to the remnant arc in the west. Representative seismic lines and bathymetric images are presented for each province, along with a description of key processes including deformation of the subducting plate, serpentinite mud volcanism, forearc faulting, potentially tsunamigenic landslides, arc volcanism, and backarc spreading. The Mariana subduction system mini-lesson requires a computer with an internet connection, powerpoint, Google Earth, and a web-browser. Questions are embedded in the powerpoint presentation that can be adapted to a specific interactive response system as needed. Optimally the lesson should be used in parallel with a GeoWall. A 3-dimensional ArcScene visualization of the Mariana system is available for download through the MARGINS mini-lessons web site. Such visualizations are particularly effective in helping students understand complex three-dimensional systems. If presented in a computer lab students will benefit from being able to explore the Mariana system using tools such as GeoMapApp.

A new general circulation model of Jupiter's atmosphere based on the UKMO Unified Model: Three-dimensional evolution of isolated vortices and zonal jets in mid-latitudes

NASA Astrophysics Data System (ADS)

Yamazaki, Y. H.; Skeet, D. R.; Read, P. L.

2004-04-01

We have been developing a new three-dimensional general circulation model for the stratosphere and troposphere of Jupiter based on the dynamical core of a portable version of the Unified Model of the UK Meteorological Office. Being one of the leading terrestrial GCMs, employed for operational weather forecasting and climate research, the Unified Model has been thoroughly tested and performance tuned for both vector and parallel computers. It is formulated as a generalized form of the standard primitive equations to handle a thick atmosphere, using a scaled pressure as the vertical coordinate. It is able to accurately simulate the dynamics of a three-dimensional fully compressible atmosphere on the whole or a part of a spherical shell at high spatial resolution in all three directions. Using the current version of the GCM, we examine the characteristics of the Jovian winds in idealized configurations based on the observed vertical structure of temperature. Our initial focus is on the evolution of isolated eddies in the mid-latitudes. Following a brief theoretical investigation of the vertical structure of the atmosphere, limited-area cyclic channel domains are used to numerically investigate the nonlinear evolution of the mid-latitude winds. First, the evolution of deep and shallow cyclones and anticyclones are tested in the atmosphere at rest to identify a preferred horizontal and vertical structure of the vortices. Then, the dependency of the migration characteristics of the vortices are investigated against modelling parameters to find that it is most sensitive to the horizontal diffusion. We also examine the hydrodynamical stability of observed subtropical jets in both northern and southern hemispheres in the three-dimensional nonlinear model as initial value problems. In both cases, it was found that the prominent jets are unstable at various scales and that vorteces of various sizes are generated including those comparable to the White Ovals and the Great Red Spot.

The high performance parallel algorithm for Unified Gas-Kinetic Scheme

NASA Astrophysics Data System (ADS)

Li, Shiyi; Li, Qibing; Fu, Song; Xu, Jinxiu

2016-11-01

A high performance parallel algorithm for UGKS is developed to simulate three-dimensional flows internal and external on arbitrary grid system. The physical domain and velocity domain are divided into different blocks and distributed according to the two-dimensional Cartesian topology with intra-communicators in physical domain for data exchange and other intra-communicators in velocity domain for sum reduction to moment integrals. Numerical results of three-dimensional cavity flow and flow past a sphere agree well with the results from the existing studies and validate the applicability of the algorithm. The scalability of the algorithm is tested both on small (1-16) and large (729-5832) scale processors. The tested speed-up ratio is near linear ashind thus the efficiency is around 1, which reveals the good scalability of the present algorithm.

Parallel Simulation of Three-Dimensional Free-Surface Fluid Flow Problems

DOE Office of Scientific and Technical Information (OSTI.GOV)

BAER,THOMAS A.; SUBIA,SAMUEL R.; SACKINGER,PHILIP A.

2000-01-18

We describe parallel simulations of viscous, incompressible, free surface, Newtonian fluid flow problems that include dynamic contact lines. The Galerlin finite element method was used to discretize the fully-coupled governing conservation equations and a ''pseudo-solid'' mesh mapping approach was used to determine the shape of the free surface. In this approach, the finite element mesh is allowed to deform to satisfy quasi-static solid mechanics equations subject to geometric or kinematic constraints on the boundaries. As a result, nodal displacements must be included in the set of problem unknowns. Issues concerning the proper constraints along the solid-fluid dynamic contact line inmore » three dimensions are discussed. Parallel computations are carried out for an example taken from the coating flow industry, flow in the vicinity of a slot coater edge. This is a three-dimensional free-surface problem possessing a contact line that advances at the web speed in one region but transitions to static behavior in another part of the flow domain. Discussion focuses on parallel speedups for fixed problem size, a class of problems of immediate practical importance.« less

Three-dimensional analysis of maxillary stability after Le Fort I osteotomy using hydroxyapatite/poly-L-lactide plate.

PubMed

Park, Jung-Hyun; Kim, Minkyu; Kim, Sang Yoon; Jung, Hwi-Dong; Jung, Young-Soo

2016-04-01

To evaluate three-dimensional change in maxillary position using biodegradable plates. A total of 53 patients who underwent orthognathic surgery using biodegradable plates were analyzed retrospectively. The position of maxilla was measured three-dimensionally using cone beam computed tomography data at preoperative (T0), 1-month postoperative (T1), and 1-year postoperative (T2) time points. Changes in the maxilla 1 year after the operation (T2-T1) were analyzed to demonstrate postoperative stability. The correlation between postoperative relapse (T2-T1) and surgical movement (T1-T0) of the maxilla was investigated. At 1-year postoperatively, no significant changes in maxillary position were noted in the antero-posterior and transverse dimensions. The anterior maxillary position in the vertical dimension also showed no significant changes, but the posterior maxillary position (posterior nasal spine, greater palatine foramen) showed a 0- to 2.98-mm relapse at 1-year postoperatively. The posterior maxilla tended to relapse inferiorly when the amount of surgical upward movement was greater than 3-3.5 mm and to relapse superiorly when the amount of surgical upward movement was less than 3-3.5 mm. For all patients, no postoperative complications in the osteofixated maxilla were observed during the follow-up period. Maxilla fixed with biodegradable plates was stable in the antero-posterior and transverse and the vertical (anterior maxilla) dimensions. Posterior maxillary vertical relapse was clinically acceptable, but relapse patterns that relate to the amount of surgical upward movement should be considered for surgical treatment planning. Copyright © 2016. Published by Elsevier Ltd.

Dynamically tunable graphene/dielectric photonic crystal transmission lines

NASA Astrophysics Data System (ADS)

Williamson, Ian; Mousavi, S. Hossein; Wang, Zheng

2015-03-01

It is well known that graphene supports plasmonic modes with high field confinement and lower losses when compared to conventional metals. Additionally, graphene features a highly tunable conductivity through which the plasmon dispersion can be modulated. Over the years these qualities have inspired a wide range of applications for graphene in the THz and infrared regimes. In this presentation we theoretically demonstrate a graphene parallel plate waveguide (PPWG) that sandwiches a 2D photonic crystal slab. The marriage of these two geometries offers a large two dimensional band gap that can be dynamically tuned over a very broad bandwidth. Our device operates in the low-THz band where the graphene PPWG supports a quasi-TEM mode with a relatively flat attenuation. Unlike conventional photonic crystal slabs, the quasi-TEM nature of the graphene PPWG mode allows the slab thickness to be less than 1/10 of the photonic crystal lattice constant. These features offer up a wealth of opportunities, including tunable metamaterials with a possible platform for large band gaps in 3D structures through tiling and stacking. Additionally, the geometry provides a platform for tunable defect cavities without needing three dimensional periodicity.

Repulsive Casimir effect from extra dimensions and Robin boundary conditions: From branes to pistons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elizalde, E.; Odintsov, S. D.; Institucio Catalana de Recerca i Estudis Avanccats

2009-03-15

We evaluate the Casimir energy and force for a massive scalar field with general curvature coupling parameter, subject to Robin boundary conditions on two codimension-one parallel plates, located on a (D+1)-dimensional background spacetime with an arbitrary internal space. The most general case of different Robin coefficients on the two separate plates is considered. With independence of the geometry of the internal space, the Casimir forces are seen to be attractive for special cases of Dirichlet or Neumann boundary conditions on both plates and repulsive for Dirichlet boundary conditions on one plate and Neumann boundary conditions on the other. For Robinmore » boundary conditions, the Casimir forces can be either attractive or repulsive, depending on the Robin coefficients and the separation between the plates, what is actually remarkable and useful. Indeed, we demonstrate the existence of an equilibrium point for the interplate distance, which is stabilized due to the Casimir force, and show that stability is enhanced by the presence of the extra dimensions. Applications of these properties in braneworld models are discussed. Finally, the corresponding results are generalized to the geometry of a piston of arbitrary cross section.« less

Native architecture of the Chlamydomonas chloroplast revealed by in situ cryo-electron tomography

PubMed Central

Engel, Benjamin D; Schaffer, Miroslava; Kuhn Cuellar, Luis; Villa, Elizabeth; Plitzko, Jürgen M; Baumeister, Wolfgang

2015-01-01

Chloroplast function is orchestrated by the organelle's intricate architecture. By combining cryo-focused ion beam milling of vitreous Chlamydomonas cells with cryo-electron tomography, we acquired three-dimensional structures of the chloroplast in its native state within the cell. Chloroplast envelope inner membrane invaginations were frequently found in close association with thylakoid tips, and the tips of multiple thylakoid stacks converged at dynamic sites on the chloroplast envelope, implicating lipid transport in thylakoid biogenesis. Subtomogram averaging and nearest neighbor analysis revealed that RuBisCO complexes were hexagonally packed within the pyrenoid, with ∼15 nm between their centers. Thylakoid stacks and the pyrenoid were connected by cylindrical pyrenoid tubules, physically bridging the sites of light-dependent photosynthesis and light-independent carbon fixation. Multiple parallel minitubules were bundled within each pyrenoid tubule, possibly serving as conduits for the targeted one-dimensional diffusion of small molecules such as ATP and sugars between the chloroplast stroma and the pyrenoid matrix. DOI: http://dx.doi.org/10.7554/eLife.04889.001 PMID:25584625

Non-parallel divergence across freshwater and marine three-spined stickleback Gasterosteus aculeatus populations.

PubMed

Pujolar, J M; Ferchaud, A L; Bekkevold, D; Hansen, M M

2017-07-01

This work investigated whether multiple freshwater populations of three-spined stickleback Gasterosteus aculeatus in different freshwater catchments in the Jutland Peninsula, Denmark, derived from the same marine populations show repeated adaptive responses. A total of 327 G. aculeatus collected at 13 sampling locations were screened for genetic variation using a combination of 70 genes putatively under selection and 26 neutral genes along with a marker linked to the ectodysplasin gene (eda), which is strongly correlated with plate armour morphs in the species. A highly significant genetic differentiation was found that was higher among different freshwater samples than between marine-freshwater samples. Tests for selection between marine and freshwater populations showed a very low degree of parallelism and no single nucleotide polymorphism was detected as outlier in all freshwater-marine pairwise comparisons, including the eda. This suggests that G. aculeatus is not necessarily the prime example of parallel local adaptation suggested in much of the literature and that important exceptions exist (i.e. the Jutland Peninsula). While marine populations in the results described here showed a high phenotype-genotype correlation at eda, a low association was found for most of the freshwater populations. The most extreme case was found in the freshwater Lake Hald where all low-plated phenotypes were either homozygotes for the allele supposed to be associated with completely plated morphs or heterozygotes, but none were homozygotes for the putative low-plated allele. Re-examination of data from seven G. aculeatus studies agrees in showing a high but partial association between phenotype-genotype at eda in G. aculeatus freshwater populations and that mismatches occur everywhere in the European regions studied (higher in some areas, i.e. Denmark). This is independent of the eda marker used. © 2017 The Fisheries Society of the British Isles.

Fractional calculus phenomenology in two-dimensional plasma models

NASA Astrophysics Data System (ADS)

Gustafson, Kyle; Del Castillo Negrete, Diego; Dorland, Bill

2006-10-01

Transport processes in confined plasmas for fusion experiments, such as ITER, are not well-understood at the basic level of fully nonlinear, three-dimensional kinetic physics. Turbulent transport is invoked to describe the observed levels in tokamaks, which are orders of magnitude greater than the theoretical predictions. Recent results show the ability of a non-diffusive transport model to describe numerical observations of turbulent transport. For example, resistive MHD modeling of tracer particle transport in pressure-gradient driven turbulence for a three-dimensional plasma reveals that the superdiffusive (2̂˜t^α where α> 1) radial transport in this system is described quantitatively by a fractional diffusion equation Fractional calculus is a generalization involving integro-differential operators, which naturally describe non-local behaviors. Our previous work showed the quantitative agreement of special fractional diffusion equation solutions with numerical tracer particle flows in time-dependent linearized dynamics of the Hasegawa-Mima equation (for poloidal transport in a two-dimensional cold-ion plasma). In pursuit of a fractional diffusion model for transport in a gyrokinetic plasma, we now present numerical results from tracer particle transport in the nonlinear Hasegawa-Mima equation and a planar gyrokinetic model. Finite Larmor radius effects will be discussed. D. del Castillo Negrete, et al, Phys. Rev. Lett. 94, 065003 (2005).

Modelling Polymer Deformation and Welding Behaviour during 3D Printing

NASA Astrophysics Data System (ADS)

McIlroy, Claire; Olmsted, Peter

2016-11-01

3D printing has the potential to transform manufacturing processes, yet improving the strength of printed parts, to equal that of traditionally-manufactured parts, remains an underlying issue. The most common method, fused deposition modelling, involves melting a thermoplastic, followed by layer-by-layer extrusion of the material to fabricate a three-dimensional object. The key to the ensuring strength at the weld between these layers is successful inter-diffusion. However, as the printed layer cools towards the glass transition temperature, the time available for diffusion is limited. In addition, the extrusion process significantly deforms the polymer micro-structure prior to welding and consequently affects how the polymers "re-entangle" across the weld. We have developed a simple model of the non-isothermal printing process to explore the effects that typical printing conditions and amorphous polymer rheology have on the ultimate weld structure. In particular, we incorporate both the stretch and orientation of the polymer using the Rolie-Poly constitutive equation to examine how the melt flows through the nozzle and is deposited onto the build plate. We then address how this deformation relaxes and contributes to the thickness and structure of the weld. National Institute for Standards and Technology (NIST) and Georgetown University.

Towards energy-efficient nonoscillatory forward-in-time integrations on lat-lon grids

NASA Astrophysics Data System (ADS)

Polkowski, Marcin; Piotrowski, Zbigniew; Ryczkowski, Adam

2017-04-01

The design of the next-generation weather prediction models calls for new algorithmic approaches allowing for robust integrations of atmospheric flow over complex orography at sub-km resolutions. These need to be accompanied by efficient implementations exposing multi-level parallelism, capable to run on modern supercomputing architectures. Here we present the recent advances in the energy-efficient implementation of the consistent soundproof/implicit compressible EULAG dynamical core of the COSMO weather prediction framework. Based on the experiences of the atmospheric dwarfs developed within H2020 ESCAPE project, we develop efficient, architecture agnostic implementations of fully three-dimensional MPDATA advection schemes and generalized diffusion operator in curvilinear coordinates and spherical geometry. We compare optimized Fortran implementation with preliminary C++ implementation employing the Gridtools library, allowing for integrations on CPU and GPU while maintaining single source code.

Facilitated Diffusion of Transcription Factor Proteins with Anomalous Bulk Diffusion.

PubMed

Liu, Lin; Cherstvy, Andrey G; Metzler, Ralf

2017-02-16

What are the physical laws of the diffusive search of proteins for their specific binding sites on DNA in the presence of the macromolecular crowding in cells? We performed extensive computer simulations to elucidate the protein target search on DNA. The novel feature is the viscoelastic non-Brownian protein bulk diffusion recently observed experimentally. We examine the influence of the protein-DNA binding affinity and the anomalous diffusion exponent on the target search time. In all cases an optimal search time is found. The relative contribution of intermittent three-dimensional bulk diffusion and one-dimensional sliding of proteins along the DNA is quantified. Our results are discussed in the light of recent single molecule tracking experiments, aiming at a better understanding of the influence of anomalous kinetics of proteins on the facilitated diffusion mechanism.

Three-dimensional particle-in-cell simulation on gain saturation effect of microchannel plate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Qiangqiang; Yuan, Zheng; Cao, Zhurong, E-mail: cao33jin@aliyun.com

We present here the results of the simulation work, using the three-dimensional particle-in-cell method, on the performance of the lead glass microchannel plate under saturated state. We calculated the electron cascade process with different DC bias voltages under both self-consistent condition and non-self-consistent condition. The comparative results have demonstrated that the strong self-consistent field can suppress the cascade process and make the microchannel plate saturated. The simulation results were also compared to the experimental data and good agreement was obtained. The simulation results also show that the electron multiplication process in the channel is accompanied by the buildup process ofmore » positive charges in the channel wall. Though the interactions among the secondary electron cloud in the channel, the positive charges in the channel wall, and the external acceleration field can make the electron-surface collision more frequent, the collision energy will be inevitably reduced, thus the electron gain will also be reduced.« less

Development of high-resolution x-ray CT system using parallel beam geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoneyama, Akio, E-mail: akio.yoneyama.bu@hitachi.com; Baba, Rika; Hyodo, Kazuyuki

2016-01-28

For fine three-dimensional observations of large biomedical and organic material samples, we developed a high-resolution X-ray CT system. The system consists of a sample positioner, a 5-μm scintillator, microscopy lenses, and a water-cooled sCMOS detector. Parallel beam geometry was adopted to attain a field of view of a few mm square. A fine three-dimensional image of birch branch was obtained using a 9-keV X-ray at BL16XU of SPring-8 in Japan. The spatial resolution estimated from the line profile of a sectional image was about 3 μm.

Optical processing furnace with quartz muffle and diffuser plate

DOEpatents

Sopori, Bhushan L.

1995-01-01

An optical furnace for annealing a process wafer comprising a source of optical energy, a quartz muffle having a door to hold the wafer for processing, and a quartz diffuser plate to diffuse the light impinging on the quartz muffle; a feedback system with a light sensor located in the door or wall of the muffle is also provided for controlling the source of optical energy. The quartz for the diffuser plate is surface etched (to give the quartz diffusive qualities) in the furnace during a high intensity burn-in process.

An experimental investigation of compressible three-dimensional boundary layer flow in annular diffusers

NASA Technical Reports Server (NTRS)

Om, Deepak; Childs, Morris E.

1987-01-01

An experimental study is described in which detailed wall pressure measurements have been obtained for compressible three-dimensional unseparated boundary layer flow in annular diffusers with and without normal shock waves. Detailed mean flow-field data were also obtained for the diffuser flow without a shock wave. Two diffuser flows with shock waves were investigated. In one case, the normal shock existed over the complete annulus whereas in the second case, the shock existed over a part of the annulus. The data obtained can be used to validate computational codes for predicting such flow fields. The details of the flow field without the shock wave show flow reversal in the circumferential direction on both inner and outer surfaces. However, there is a lag in the flow reversal between the inner nad the outer surfaces. This is an interesting feature of this flow and should be a good test for the computational codes.

Cattaneo-Christov double-diffusion theory for three-dimensional flow of viscoelastic nanofluid with the effect of heat generation/absorption

NASA Astrophysics Data System (ADS)

Hayat, Tasawar; Qayyum, Sajid; Shehzad, Sabir Ali; Alsaedi, Ahmed

2018-03-01

The present research article focuses on three-dimensional flow of viscoelastic(second grade) nanofluid in the presence of Cattaneo-Christov double-diffusion theory. Flow caused is due to stretching sheet. Characteristics of heat transfer are interpreted by considering the heat generation/absorption. Nanofluid theory comprises of Brownian motion and thermophoresis. Cattaneo-Christov double-diffusion theory is introduced in the energy and concentration expressions. Such diffusions are developed as a part of formulating the thermal and solutal relaxation times framework. Suitable variables are implemented for the conversion of partial differential systems into a sets of ordinary differential equations. The transformed expressions have been explored through homotopic algorithm. Behavior of sundry variables on the velocities, temperature and concentration are scrutinized graphically. Numerical values of skin friction coefficients are also calculated and examined. Here thermal field enhances for heat generation parameter while reverse situation is noticed for heat absorption parameter.

On the local well-posedness and a Prodi-Serrin-type regularity criterion of the three-dimensional MHD-Boussinesq system without thermal diffusion

NASA Astrophysics Data System (ADS)

Larios, Adam; Pei, Yuan

2017-07-01

We prove a Prodi-Serrin-type global regularity condition for the three-dimensional Magnetohydrodynamic-Boussinesq system (3D MHD-Boussinesq) without thermal diffusion, in terms of only two velocity and two magnetic components. To the best of our knowledge, this is the first Prodi-Serrin-type criterion for such a 3D hydrodynamic system which is not fully dissipative, and indicates that such an approach may be successful on other systems. In addition, we provide a constructive proof of the local well-posedness of solutions to the fully dissipative 3D MHD-Boussinesq system, and also the fully inviscid, irresistive, non-diffusive MHD-Boussinesq equations. We note that, as a special case, these results include the 3D non-diffusive Boussinesq system and the 3D MHD equations. Moreover, they can be extended without difficulty to include the case of a Coriolis rotational term.

NASA Tech Briefs, September 2010

NASA Technical Reports Server (NTRS)

2010-01-01

Topics covered include: Instrument for Measuring Thermal Conductivity of Materials at Low Temperatures; Multi-Axis Accelerometer Calibration System; Pupil Alignment Measuring Technique and Alignment Reference for Instruments or Optical Systems; Autonomous System for Monitoring the Integrity of Composite Fan Housings; A Safe, Self-Calibrating, Wireless System for Measuring Volume of Any Fuel at Non-Horizontal Orientation; Adaptation of the Camera Link Interface for Flight-Instrument Applications; High-Performance CCSDS Encapsulation Service Implementation in FPGA; High-Performance CCSDS AOS Protocol Implementation in FPGA; Advanced Flip Chips in Extreme Temperature Environments; Diffuse-Illumination Systems for Growing Plants; Microwave Plasma Hydrogen Recovery System; Producing Hydrogen by Plasma Pyrolysis of Methane; Self-Deployable Membrane Structures; Reactivation of a Tin-Oxide-Containing Catalys; Functionalization of Single-Wall Carbon Nanotubes by Photo-Oxidation; Miniature Piezoelectric Macro-Mass Balance; Acoustic Liner for Turbomachinery Applications; Metering Gas Strut for Separating Rocket Stages; Large-Flow-Area Flow-Selective Liquid/Gas Separator; Counterflowing Jet Subsystem Design; Water Tank with Capillary Air/Liquid Separation; True Shear Parallel Plate Viscometer; Focusing Diffraction Grating Element with Aberration Control; Universal Millimeter-Wave Radar Front End; Mode Selection for a Single-Frequency Fiber Laser; Qualification and Selection of Flight Diode Lasers for Space Applications; Plenoptic Imager for Automated Surface Navigation; Maglev Facility for Simulating Variable Gravity; Hybrid AlGaN-SiC Avalanche Photodiode for Deep-UV Photon Detection; High-Speed Operation of Interband Cascade Lasers; 3D GeoWall Analysis System for Shuttle External Tank Foreign Object Debris Events; Charge-Spot Model for Electrostatic Forces in Simulation of Fine Particulates; Hidden Statistics Approach to Quantum Simulations; Reconstituted Three-Dimensional Interactive Imaging; Determining Atmospheric-Density Profile of Titan; Digital Microfluidics Sample Analyzer; Radiation Protection Using Carbon Nanotube Derivatives; Process to Selectively Distinguish Viable from Non-Viable Bacterial Cells; and TEAMS Model Analyzer.

Hotspot-Ridge Interaction: Shaping the Geometry of Mid-Ocean Ridges

NASA Astrophysics Data System (ADS)

Mittelstaedt, E.; Ito, G.

2004-12-01

Surface manifestations of hotspot-ridge interaction include geochemical anomalies, elevated ridge topography, negative gravity anomalies, off-axis volcanic lineaments, and ridge reorganization events. The last of these is expressed as either "captured" ridge segments due to asymmetric spreading, such as at the Galapagos, or as discrete jumps of the ridge axis toward the hotspot, such as at the Iceland, Tristan de Cuhna, Discovery, Shona, Louisville, Kerguelen, and Reunion hotspots. Mid-ocean ridge axis reorganizations through discrete jumps will cause variations in local volcanic patterns, lead to changes in overall plate shape and ridge axis morphology, and alter local mantle flow patterns. It has been proposed that discrete ridge jumps are a product of interaction between the lithosphere and a mantle plume. We examine this hypothesis using thin plate theory coupled with continuum damage mechanics to calculate the two-dimensional (plan-view) pattern of depth-integrated stresses in a plate of varying thickness with weakening due to volcanism at the ridge and above the plume center. Forces on the plate include plume shear, plate parallel gravitational forces due to buoyant uplift, and a prescribed velocity of plate motion along the edges of the model. We explore these forces and the effect of damage as mechanisms that may be required to predict ridge jumps.

Cross-scale transport processes in the three-dimensional Kelvin-Helmholtz instability

NASA Astrophysics Data System (ADS)

Delamere, P. A.; Burkholder, B. L.; Ma, X.; Nykyri, K.

2017-12-01

The Kelvin-Helmholtz (KH) instability is a crucial aspect of the solar wind interaction with the giant magnetospheres. Rapid internal rotation of the magnetodisc produces conditions favorable for the growth of KH vortices along much of the equatorial magnetopause boundary. Pronounced dawn/dusk asymmetries at Jupiter and Saturn indicate a robust interaction with the solar wind. Using three-dimensional hybrid simulations we investigate the transport processes associated with the flow shear-driven KH instability. Of particular importance is small-scale and intermittent reconnection generated by the twisting of the magnetic field into configurations with antiparallel components. In three-dimensions strong guide field reconnection can occur even for initially parallel magnetic field configurations. Often the twisting motion leads to pairs of reconnection sites that can operate asynchronously, generating intermittent open flux and Maxwell stresses at the magnetopause boundary. We quantify the generation of open flux using field line tracing methods, determine the Reynolds and Maxwell stresses, and evaluate the mass transport as functions of magnetic shear, velocity shear, electron pressure and plasma beta. These results are compared with magnetohydrodynamic simulations (Ma et al., 2017). In addition, we present preliminary results for the role of cross-scale coupling processes, from fluid to ion scales. In particular, we characterize small-scale waves and the their role in mixing, diffusing and heating plasma at the magnetopause boundary.

Electrochemical Device Comprising an Electrically-Conductive, Selectively-Permeable Membrane

NASA Technical Reports Server (NTRS)

Laicer, Castro S. T. (Inventor); Mittelsteadt, Cortney K. (Inventor); Harrison, Katherine E. (Inventor); McPheeters, Bryn M. (Inventor)

2017-01-01

An electrochemical device, such as a fuel cell or an electrolyzer. In one embodiment, the electrochemical device includes a membrane electrode assembly (MEA), an anodic gas diffusion medium in contact with the anode of the MEA, a cathodic gas diffusion medium in contact with the cathode, a first bipolar plate in contact with the anodic gas diffusion medium, and a second bipolar plate in contact with the cathodic gas diffusion medium. Each of the bipolar plates includes an electrically-conductive, non-porous, liquid-permeable, substantially gas-impermeable membrane in contact with its respective gas diffusion medium, the membrane including a solid polymer electrolyte and a non-particulate, electrically-conductive material, such as carbon nanotubes, carbon nanofibers, and/or metal nanowires. In addition, each bipolar plate also includes an electrically-conductive fluid chamber in contact with the electrically-conductive, selectively-permeable membrane and further includes a non-porous and electrically-conductive plate in contact with the fluid chamber.

Application of advanced computational codes in the design of an experiment for a supersonic throughflow fan rotor

NASA Technical Reports Server (NTRS)

Wood, Jerry R.; Schmidt, James F.; Steinke, Ronald J.; Chima, Rodrick V.; Kunik, William G.

1987-01-01

Increased emphasis on sustained supersonic or hypersonic cruise has revived interest in the supersonic throughflow fan as a possible component in advanced propulsion systems. Use of a fan that can operate with a supersonic inlet axial Mach number is attractive from the standpoint of reducing the inlet losses incurred in diffusing the flow from a supersonic flight Mach number to a subsonic one at the fan face. The design of the experiment using advanced computational codes to calculate the components required is described. The rotor was designed using existing turbomachinery design and analysis codes modified to handle fully supersonic axial flow through the rotor. A two-dimensional axisymmetric throughflow design code plus a blade element code were used to generate fan rotor velocity diagrams and blade shapes. A quasi-three-dimensional, thin shear layer Navier-Stokes code was used to assess the performance of the fan rotor blade shapes. The final design was stacked and checked for three-dimensional effects using a three-dimensional Euler code interactively coupled with a two-dimensional boundary layer code. The nozzle design in the expansion region was analyzed with a three-dimensional parabolized viscous code which corroborated the results from the Euler code. A translating supersonic diffuser was designed using these same codes.

Flow reversal, convection, and modeling in the DIII-D divertor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boedo, J.A.; Porter, G.D.; Schaffer, M.J.

1998-12-01

Measurements of the parallel Mach number of background plasma in the DIII-D tokamak divertor [M. A. Mahdavi {ital et al.} in {ital Proceedings, 16th International Conference}, Montreal, 1996 (International Atomic Energy Agency, Vienna, 1997) Vol. I, p. 397] were performed using a fast scanning Mach probe. The parallel particle flow shows evidence of complex behavior such as reverse flow, i.e., flow away from the target plate, stagnant flow, and large scale convection. For detached discharges, measurements confirm predictions of convective flow towards the divertor target plate at near sound speed over large regions in the divertor. The resulting convected heatmore » flux is a dominant heat transport mechanism in the divertor. For attached discharges with high recycling, particle flow reversal in a thin region at or near the outer separatrix, thereby confirming the existence of a mechanism by which impurities can be transported away from the divertor target plates. Modeling results from the two-dimensional fluid code UEDGE [G. D. Porter and the DIII-D Team, {open_quotes}Divertor characterization experiments and modelling in DIII-D,{close_quotes} in {ital Proceedings of the 23rd European Conference on Controlled Fusion and Plasma Physics}, 24{endash}28 June 1996, Kiev, Ukraine (European Physical Society, Petit-Lancy, Switzerland, 1996), Vol. 20C, Part II, p. 699] can reproduce the main features of the experimental observations. {copyright} {ital 1998 American Institute of Physics.}« less

Three-dimensional photoacoustic tomography based on graphics-processing-unit-accelerated finite element method.

PubMed

Peng, Kuan; He, Ling; Zhu, Ziqiang; Tang, Jingtian; Xiao, Jiaying

2013-12-01

Compared with commonly used analytical reconstruction methods, the frequency-domain finite element method (FEM) based approach has proven to be an accurate and flexible algorithm for photoacoustic tomography. However, the FEM-based algorithm is computationally demanding, especially for three-dimensional cases. To enhance the algorithm's efficiency, in this work a parallel computational strategy is implemented in the framework of the FEM-based reconstruction algorithm using a graphic-processing-unit parallel frame named the "compute unified device architecture." A series of simulation experiments is carried out to test the accuracy and accelerating effect of the improved method. The results obtained indicate that the parallel calculation does not change the accuracy of the reconstruction algorithm, while its computational cost is significantly reduced by a factor of 38.9 with a GTX 580 graphics card using the improved method.

Mathematical modeling of a dynamic thin plate deformation in acoustoelasticity problems

NASA Astrophysics Data System (ADS)

Badriev, I. B.; Paimuhin, V. N.

2018-01-01

The coupled problem of planar acoustic wave propagation through a composite plate covered with a second damping layer with a large logarithmic decrement of oscillations is formulated. The aerohydrodynamic interaction of a plate with external acoustic environment is described by three-dimensional wave equations and the mechanical behavior of a two-layer plate by the classical Kirchhoff-Love model. An exact analytic solution of the problem is found for the case of hinged support of the edges of a plate. On the basis of this, the parameters of the covering damping layer were found, under which it is possible to achieve a practically complete damping of the plate vibration under resonant modes of its acoustic loading.

Speckle contrast optical tomography: A new method for deep tissue three-dimensional tomography of blood flow

PubMed Central

Varma, Hari M.; Valdes, Claudia P.; Kristoffersen, Anna K.; Culver, Joseph P.; Durduran, Turgut

2014-01-01

A novel tomographic method based on the laser speckle contrast, speckle contrast optical tomography (SCOT) is introduced that allows us to reconstruct three dimensional distribution of blood flow in deep tissues. This method is analogous to the diffuse optical tomography (DOT) but for deep tissue blood flow. We develop a reconstruction algorithm based on first Born approximation to generate three dimensional distribution of flow using the experimental data obtained from tissue simulating phantoms. PMID:24761306

Progress of High Efficiency Centrifugal Compressor Simulations Using TURBO

NASA Technical Reports Server (NTRS)

Kulkarni, Sameer; Beach, Timothy A.

2017-01-01

Three-dimensional, time-accurate, and phase-lagged computational fluid dynamics (CFD) simulations of the High Efficiency Centrifugal Compressor (HECC) stage were generated using the TURBO solver. Changes to the TURBO Parallel Version 4 source code were made in order to properly model the no-slip boundary condition along the spinning hub region for centrifugal impellers. A startup procedure was developed to generate a converged flow field in TURBO. This procedure initialized computations on a coarsened mesh generated by the Turbomachinery Gridding System (TGS) and relied on a method of systematically increasing wheel speed and backpressure. Baseline design-speed TURBO results generally overpredicted total pressure ratio, adiabatic efficiency, and the choking flow rate of the HECC stage as compared with the design-intent CFD results of Code Leo. Including diffuser fillet geometry in the TURBO computation resulted in a 0.6 percent reduction in the choking flow rate and led to a better match with design-intent CFD. Diffuser fillets reduced annulus cross-sectional area but also reduced corner separation, and thus blockage, in the diffuser passage. It was found that the TURBO computations are somewhat insensitive to inlet total pressure changing from the TURBO default inlet pressure of 14.7 pounds per square inch (101.35 kilopascals) down to 11.0 pounds per square inch (75.83 kilopascals), the inlet pressure of the component test. Off-design tip clearance was modeled in TURBO in two computations: one in which the blade tip geometry was trimmed by 12 mils (0.3048 millimeters), and another in which the hub flow path was moved to reflect a 12-mil axial shift in the impeller hub, creating a step at the hub. The one-dimensional results of these two computations indicate non-negligible differences between the two modeling approaches.

Biomechanical comparison of orthogonal versus parallel double plating systems in intraarticular distal humerus fractures.

PubMed

Atalar, Ata C; Tunalı, Onur; Erşen, Ali; Kapıcıoğlu, Mehmet; Sağlam, Yavuz; Demirhan, Mehmet S

2017-01-01

In intraarticular distal humerus fractures, internal fixation with double plates is the gold standard treatment. However the optimal plate configuration is not clear in the literature. The aim of this study was to compare the biomechanical stability of the parallel and the orthogonal anatomical locking plating systems in intraarticular distal humerus fractures in artificial humerus models. Intraarticular distal humerus fracture (AO13-C2) with 5 mm metaphyseal defect was created in sixteen artificial humeral models. Models were fixed with either orthogonal or parallel plating systems with locking screws (Acumed elbow plating systems). Both systems were tested for their stiffness with loads in axial compression, varus, valgus, anterior and posterior bending. Then plastic deformation after cyclic loading in posterior bending and load to failure in posterior bending were tested. The failure mechanisms of all the samples were observed. Stiffness values in every direction were not significantly different among the orthogonal and the parallel plating groups. There was no statistical difference between the two groups in plastic deformation values (0.31 mm-0.29 mm) and load to failure tests in posterior bending (372.4 N-379.7 N). In the orthogonal plating system most of the failures occurred due to the proximal shaft fracture, whereas in the parallel plating system failure occurred due to the shift of the most distal screw in proximal fragment. Our study showed that both plating systems had similar biomechanical stabilities when anatomic plates with distal locking screws were used in intraarticular distal humerus fractures in artificial humerus models. Copyright © 2016 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.

Heat source reconstruction from noisy temperature fields using a gradient anisotropic diffusion filter

NASA Astrophysics Data System (ADS)

Beitone, C.; Balandraud, X.; Delpueyo, D.; Grédiac, M.

2017-01-01

This paper presents a post-processing technique for noisy temperature maps based on a gradient anisotropic diffusion (GAD) filter in the context of heat source reconstruction. The aim is to reconstruct heat source maps from temperature maps measured using infrared (IR) thermography. Synthetic temperature fields corrupted by added noise are first considered. The GAD filter, which relies on a diffusion process, is optimized to retrieve as well as possible a heat source concentration in a two-dimensional plate. The influence of the dimensions and the intensity of the heat source concentration are discussed. The results obtained are also compared with two other types of filters: averaging filter and Gaussian derivative filter. The second part of this study presents an application for experimental temperature maps measured with an IR camera. The results demonstrate the relevancy of the GAD filter in extracting heat sources from noisy temperature fields.

Experimental study of shock-accelerated inclined heavy gas cylinder

DOE PAGES

Olmstead, Dell; Wayne, Patrick; Yoo, Jae-Hwun; ...

2017-05-23

An experimental study examines shock acceleration with an initially diffuse cylindrical column of sulfur hexafluoride surrounded by air and inclined with respect to the shock front. Three-dimensional vorticity deposition produces flow patterns whose evolution is captured with planar laser-induced fluorescence in two planes. Both planes are thus parallel to the direction of the shock propagation. The first plane is vertical and passes through the axis of the column. The second visualization plane is normal to the first plane and passes through the centerline of the shock tube. Vortex formation in the vertical and centerline planes is initially characterized by differentmore » rates and morphologies due to differences in initial vorticity deposition. In the vertical plane, the vortex structure manifests a periodicity that varies with Mach number. The dominant wavelength in the vertical plane can be related to the geometry and compressibility of the initial conditions. At later times, the vortex interaction produces a complex and irregular three-dimensional pattern suggesting transition to turbulence. We present highly repeatable experimental data for Mach numbers 1.13, 1.4, 1.7, and 2.0 at column incline angles of 0, 20, and 30 degrees for about 50 nominal cylinder diameters (30 cm) of downstream travel.« less

Modeling of composite beams and plates for static and dynamic analysis

NASA Technical Reports Server (NTRS)

Hodges, Dewey H.

1992-01-01

A rigorous theory and the corresponding computational algorithms were developed for through-the-thickness analysis of composite plates. This type of analysis is needed in order to find the elastic stiffness constants of a plate. Additionally, the analysis is used to post-process the resulting plate solution in order to find approximate three-dimensional displacement, strain, and stress distributions throughout the plate. It was decided that the variational-asymptotical method (VAM) would serve as a suitable framework in which to solve these types of problems. Work during this reporting period has progressed along two lines: (1) further evaluation of neo-classical plate theory (NCPT) as applied to shear-coupled laminates; and (2) continued modeling of plates with nonuniform thickness.

Diffuse scattering in relaxor ferroelectrics: true three-dimensional mapping, experimental artefacts and modelling.

PubMed

Bosak, A; Chernyshov, D; Vakhrushev, Sergey; Krisch, M

2012-01-01

The available body of experimental data in terms of the relaxor-specific component of diffuse scattering is critically analysed and a collection of related models is reviewed; the sources of experimental artefacts and consequent failures of modelling efforts are enumerated. Furthermore, it is shown that the widely used concept of polar nanoregions as individual static entities is incompatible with the experimental diffuse scattering results. Based on the synchrotron diffuse scattering three-dimensional data set taken for the prototypical ferroelectric relaxor lead magnesium niobate-lead titanate (PMN-PT), a new parameterization of diffuse scattering in relaxors is presented and a simple phenomenological picture is proposed to explain the unusual properties of the relaxor behaviour. The model assumes a specific slowly changing displacement pattern, which is indirectly controlled by the low-energy acoustic phonons of the system. The model provides a qualitative but rather detailed explanation of temperature, pressure and electric-field dependence of diffuse neutron and X-ray scattering, as well as of the existence of a hierarchy in the relaxation times of these materials.

Three-dimensional tomographic mapping related to primary stability and structural miniscrew characteristics.

PubMed

Silvestrini Biavati, A; Tecco, S; Migliorati, M; Festa, F; Panza, G; Marzo, G; Gherlone, E; Tetè, S

2011-05-01

To evaluate the maxilla, mandible, and cortical plates on computerized tomographic (CT) scans to achieve accurate three-dimensional bone thickness measurements. We selected the CT scans of 25 subjects (among 102), aged 18-58 years (10 men, 15 women), with nearly complete dentition. We performed interradicular and bucco-lingual (including cortical plate thickness) measurements in dental areas distal to the canines in both alveolar arches, at three levels (5, 8, and 11 mm) from the alveolar ridge. The mean thicknesses of the cortical plates in the maxilla were 1.10 mm buccally and 1.27 mm on the palatal side (p < 0.05). In the mandible, cortical plates were 2.23 mm buccally and 2.02 mm lingually. Mandibular buccal and lingual cortical plates became thicker distally in the second and third molar areas. There was considerable variation in cortical thickness (from 0.25 to 5.50 mm). Based on interradicular distances, only 13% of measured sites in the maxilla were suitable for miniscrew insertion (≥3.3 mm), but 63% of sites were suitable in the mandible. This study showed considerable individual variation in bone thickness. Our data suggested that the palatal/lingual side may provide greater primary stability for miniscrews. The palatal area, between the second upper bicuspid and the first molar, appeared to be the most suitable area for tapered 7- to 9-mm miniscrews, starting at 1.5-2 mm from the alveolar crest. © 2011 John Wiley & Sons A/S.

Dimensional stabilization of southern pines

Treesearch

E.T. Choong; H.M. Barnes

1969-01-01

The effectiveness of five dimensional stabilizing agents and three impregnation methods on southern pine was determined. Four southern pine species were studies in order to determine the effect of wood factors. The best dimensional stability was obtained when the wood was preswollen and the chemical was impregnated by a diffusion process. In general, polyethylene...

Experimental study on evaluation and optimization of tilt angle of parallel-plate electrodes using electrocoagulation device for oily water demulsification.

PubMed

Liu, Yang; Jiang, Wen-Ming; Yang, Jie; Li, Yu-Xing; Chen, Ming-Can; Li, Jian-Na

2017-08-01

Tilt angle of parallel-plate electrodes (APE) is very important as it improves the economy of diffusion controlled Electrocoagulation (EC) processes. This study aimed to evaluate and optimize APE of a self-made EC device including integrally rotary electrodes, at a fixed current density of 120 Am -2 . The APEs investigated in this study were selected at 0°, 30°, 45°, 60°, 90°, and a special value (α (d) ) which was defined as a special orientation of electrode when the upper end of anode and the lower end of cathode is in a line vertical to the bottom of reactor. Experiments were conducted to determine the optimum APE for demulsification process using four evaluation indexes, as: oil removal efficiency in the center between electrodes; energy consumption and Al consumption, and besides, a novel universal evaluation index named as evenness index of oil removal efficiency employed to fully reflect distribution characteristics of demulsification efficiency. At a given plate spacing of 4 cm, the optimal APE was found to be α (d) because of its potential of enhancing the mass transfer process within whole EC reactor without addition, external mechanical stirring energy, and finally the four evaluation indexed are 97.07%, 0.11 g Al g -1 oil, 2.99 kwhkg -1 oil, 99.97% and 99.97%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Global Dynamic Numerical Simulations of Plate Tectonic Reorganizations

NASA Astrophysics Data System (ADS)

Morra, G.; Quevedo, L.; Butterworth, N.; Matthews, K. J.; Müller, D.

2010-12-01

We use a new numerical approach for global geodynamics to investigate the origin of present global plate motion and to identify the causes of the last two global tectonic reorganizations occurred about 50 and 100 million years ago (Ma) [1]. While the 50 Ma event is the most well-known global plate-mantle event, expressed by the bend in the Hawaiian-Emperor volcanic chain, a prominent plate reorganization at about 100 Ma, although presently little studied, is clearly indicated by a major bend in the fracture zones in the Indian Ocean and by a change in Pacific plate motion [2]. Our workflow involves turning plate reconstructions into surface meshes that are subsequently employed as initial conditions for global Boundary Element numerical models. The tectonic setting that anticipates the reorganizations is processed with the software GPlates, combining the 3D mesh of the paleo-plate morphology and the reconstruction of paleo-subducted slabs, elaborated from tectonic history [3]. All our models involve the entire planetary system, are fully dynamic, have free surface, are characterized by a spectacular computational speed due to the simultaneous use of the multi-pole algorithm and the Boundary Element formulation and are limited only by the use of sharp material property variations [4]. We employ this new tool to unravel the causes of plate tectonic reorganizations, producing and comparing global plate motion with the reconstructed ones. References: [1] Torsvik, T., Müller, R.D., Van der Voo, R., Steinberger, B., and Gaina, C., 2008, Global Plate Motion Frames: Toward a unified model: Reviews in Geophysics, VOL. 46, RG3004, 44 PP., 2008 [2] Wessel, P. and Kroenke, L.W. Pacific absolute plate motion since 145 Ma: An assessment of the fixed hot spot hypothesis. Journal of Geophysical Research, Vol 113, B06101, 2008 [3] L. Quevedo, G. Morra, R. D. Mueller. Parallel Fast Multipole Boundary Element Method for Crustal Dynamics, Proceeding 9th World Congress and 4th Asian Pacific Congress on Computational Mechanics, July 2010, iopscience.iop.org/1757-899X/10/1/012012. [4] G. Morra, P. Chatelain, P. Tackley and P. Koumoutzakos, 2007, Large scale three-dimensional boundary element simulation of subduction, in Proceeding International Conference on Computational Science - Part III, LNCS 4489, pp. 1122-1129. Interaction between two subducting slabs.

Full-Scale Direct Numerical Simulation of Two- and Three-Dimensional Instabilities and Rivulet Formulation in Heated Falling Films

NASA Technical Reports Server (NTRS)

Krishnamoorthy, S.; Ramaswamy, B.; Joo, S. W.

1995-01-01

A thin film draining on an inclined plate has been studied numerically using finite element method. Three-dimensional governing equations of continuity, momentum and energy with a moving boundary are integrated in an arbitrary Lagrangian Eulerian frame of reference. Kinematic equation is solved to precisely update interface location. Rivulet formation based on instability mechanism has been simulated using full-scale computation. Comparisons with long-wave theory are made to validate the numerical scheme. Detailed analysis of two- and three-dimensional nonlinear wave formation and spontaneous rupture forming rivulets under the influence of combined thermocapillary and surface-wave instabilities is performed.

Vibration control of multiferroic fibrous composite plates using active constrained layer damping

NASA Astrophysics Data System (ADS)

Kattimani, S. C.; Ray, M. C.

2018-06-01

Geometrically nonlinear vibration control of fiber reinforced magneto-electro-elastic or multiferroic fibrous composite plates using active constrained layer damping treatment has been investigated. The piezoelectric (BaTiO3) fibers are embedded in the magnetostrictive (CoFe2O4) matrix forming magneto-electro-elastic or multiferroic smart composite. A three-dimensional finite element model of such fiber reinforced magneto-electro-elastic plates integrated with the active constrained layer damping patches is developed. Influence of electro-elastic, magneto-elastic and electromagnetic coupled fields on the vibration has been studied. The Golla-Hughes-McTavish method in time domain is employed for modeling a constrained viscoelastic layer of the active constrained layer damping treatment. The von Kármán type nonlinear strain-displacement relations are incorporated for developing a three-dimensional finite element model. Effect of fiber volume fraction, fiber orientation and boundary conditions on the control of geometrically nonlinear vibration of the fiber reinforced magneto-electro-elastic plates is investigated. The performance of the active constrained layer damping treatment due to the variation of piezoelectric fiber orientation angle in the 1-3 Piezoelectric constraining layer of the active constrained layer damping treatment has also been emphasized.

Chinks in Solar Dynamo Theory: Turbulent Diffusion, Dynamo Waves and Magnetic Helicity

NASA Technical Reports Server (NTRS)

DeLuca, E. E.; Wagner, William J. (Technical Monitor)

2001-01-01

We have investigated the generation of magnetic fields in the Sun using two-dimensional and three-dimensional numerical simulations. The results of our investigations have been presented at scientific meetings and published.

Linear and Nonlinear Analysis of Magnetic Bearing Bandwidth Due to Eddy Current Limitations

NASA Technical Reports Server (NTRS)

Kenny, Andrew; Palazzolo, Alan

2000-01-01

Finite element analysis was used to study the bandwidth of alloy hyperco50a and silicon iron laminated rotors and stators in magnetic bearings. A three dimensional model was made of a heteropolar bearing in which all the flux circulated in the plane of the rotor and stator laminate. A three dimensional model of a plate similar to the region of a pole near the gap was also studied with a very fine mesh. Nonlinear time transient solutions for the net flux carried by the plate were compared to steady state time harmonic solutions. Both linear and quasi-nonlinear steady state time harmonic solutions were calculated and compared. The finite element solutions for power loss and flux bandwidth were compared to those determined from classical analytical solutions to Maxwell's equations.

Mn-silicide nanostructures aligned on massively parallel silicon nano-ribbons

NASA Astrophysics Data System (ADS)

De Padova, Paola; Ottaviani, Carlo; Ronci, Fabio; Colonna, Stefano; Olivieri, Bruno; Quaresima, Claudio; Cricenti, Antonio; Dávila, Maria E.; Hennies, Franz; Pietzsch, Annette; Shariati, Nina; Le Lay, Guy

2013-01-01

The growth of Mn nanostructures on a 1D grating of silicon nano-ribbons is investigated at atomic scale by means of scanning tunneling microscopy, low energy electron diffraction and core level photoelectron spectroscopy. The grating of silicon nano-ribbons represents an atomic scale template that can be used in a surface-driven route to control the combination of Si with Mn in the development of novel materials for spintronics devices. The Mn atoms show a preferential adsorption site on silicon atoms, forming one-dimensional nanostructures. They are parallel oriented with respect to the surface Si array, which probably predetermines the diffusion pathways of the Mn atoms during the process of nanostructure formation.

Mn-silicide nanostructures aligned on massively parallel silicon nano-ribbons.

PubMed

De Padova, Paola; Ottaviani, Carlo; Ronci, Fabio; Colonna, Stefano; Olivieri, Bruno; Quaresima, Claudio; Cricenti, Antonio; Dávila, Maria E; Hennies, Franz; Pietzsch, Annette; Shariati, Nina; Le Lay, Guy

2013-01-09

The growth of Mn nanostructures on a 1D grating of silicon nano-ribbons is investigated at atomic scale by means of scanning tunneling microscopy, low energy electron diffraction and core level photoelectron spectroscopy. The grating of silicon nano-ribbons represents an atomic scale template that can be used in a surface-driven route to control the combination of Si with Mn in the development of novel materials for spintronics devices. The Mn atoms show a preferential adsorption site on silicon atoms, forming one-dimensional nanostructures. They are parallel oriented with respect to the surface Si array, which probably predetermines the diffusion pathways of the Mn atoms during the process of nanostructure formation.

Nonlinear viscoplasticity in ASPECT: benchmarking and applications to subduction

NASA Astrophysics Data System (ADS)

Glerum, Anne; Thieulot, Cedric; Fraters, Menno; Blom, Constantijn; Spakman, Wim

2018-03-01

ASPECT (Advanced Solver for Problems in Earth's ConvecTion) is a massively parallel finite element code originally designed for modeling thermal convection in the mantle with a Newtonian rheology. The code is characterized by modern numerical methods, high-performance parallelism and extensibility. This last characteristic is illustrated in this work: we have extended the use of ASPECT from global thermal convection modeling to upper-mantle-scale applications of subduction.

Subduction modeling generally requires the tracking of multiple materials with different properties and with nonlinear viscous and viscoplastic rheologies. To this end, we implemented a frictional plasticity criterion that is combined with a viscous diffusion and dislocation creep rheology. Because ASPECT uses compositional fields to represent different materials, all material parameters are made dependent on a user-specified number of fields.

The goal of this paper is primarily to describe and verify our implementations of complex, multi-material rheology by reproducing the results of four well-known two-dimensional benchmarks: the indentor benchmark, the brick experiment, the sandbox experiment and the slab detachment benchmark. Furthermore, we aim to provide hands-on examples for prospective users by demonstrating the use of multi-material viscoplasticity with three-dimensional, thermomechanical models of oceanic subduction, putting ASPECT on the map as a community code for high-resolution, nonlinear rheology subduction modeling.

78 FR 23905 - Diffusion-Annealed, Nickel-Plated Flat-Rolled Steel Products From Japan: Initiation of...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-23

...-Plated Flat-Rolled Steel Products From Japan: Initiation of Antidumping Duty Investigation AGENCY: Import... products from Japan (``certain nickel-plated, flat-rolled steel''), filed in proper form by Thomas Steel... Antidumping Duty Petition on Diffusion-Annealed, Nickel- Plated Steel Flat-Rolled Products from Japan, dated...

3DScapeCS: application of three dimensional, parallel, dynamic network visualization in Cytoscape

PubMed Central

2013-01-01

Background The exponential growth of gigantic biological data from various sources, such as protein-protein interaction (PPI), genome sequences scaffolding, Mass spectrometry (MS) molecular networking and metabolic flux, demands an efficient way for better visualization and interpretation beyond the conventional, two-dimensional visualization tools. Results We developed a 3D Cytoscape Client/Server (3DScapeCS) plugin, which adopted Cytoscape in interpreting different types of data, and UbiGraph for three-dimensional visualization. The extra dimension is useful in accommodating, visualizing, and distinguishing large-scale networks with multiple crossed connections in five case studies. Conclusions Evaluation on several experimental data using 3DScapeCS and its special features, including multilevel graph layout, time-course data animation, and parallel visualization has proven its usefulness in visualizing complex data and help to make insightful conclusions. PMID:24225050

3D-PDR: Three-dimensional photodissociation region code

NASA Astrophysics Data System (ADS)

Bisbas, T. G.; Bell, T. A.; Viti, S.; Yates, J.; Barlow, M. J.

2018-03-01

3D-PDR is a three-dimensional photodissociation region code written in Fortran. It uses the Sundials package (written in C) to solve the set of ordinary differential equations and it is the successor of the one-dimensional PDR code UCL_PDR (ascl:1303.004). Using the HEALpix ray-tracing scheme (ascl:1107.018), 3D-PDR solves a three-dimensional escape probability routine and evaluates the attenuation of the far-ultraviolet radiation in the PDR and the propagation of FIR/submm emission lines out of the PDR. The code is parallelized (OpenMP) and can be applied to 1D and 3D problems.

Fractional Steps methods for transient problems on commodity computer architectures

NASA Astrophysics Data System (ADS)

Krotkiewski, M.; Dabrowski, M.; Podladchikov, Y. Y.

2008-12-01

Fractional Steps methods are suitable for modeling transient processes that are central to many geological applications. Low memory requirements and modest computational complexity facilitates calculations on high-resolution three-dimensional models. An efficient implementation of Alternating Direction Implicit/Locally One-Dimensional schemes for an Opteron-based shared memory system is presented. The memory bandwidth usage, the main bottleneck on modern computer architectures, is specially addressed. High efficiency of above 2 GFlops per CPU is sustained for problems of 1 billion degrees of freedom. The optimized sequential implementation of all 1D sweeps is comparable in execution time to copying the used data in the memory. Scalability of the parallel implementation on up to 8 CPUs is close to perfect. Performing one timestep of the Locally One-Dimensional scheme on a system of 1000 3 unknowns on 8 CPUs takes only 11 s. We validate the LOD scheme using a computational model of an isolated inclusion subject to a constant far field flux. Next, we study numerically the evolution of a diffusion front and the effective thermal conductivity of composites consisting of multiple inclusions and compare the results with predictions based on the differential effective medium approach. Finally, application of the developed parabolic solver is suggested for a real-world problem of fluid transport and reactions inside a reservoir.

Resistance of a plate in parallel flow at low Reynolds numbers

NASA Technical Reports Server (NTRS)

Janour, Zbynek

1951-01-01

The present paper gives the results of measurements of the resistance of a plate placed parallel to the flow in the range of Reynolds numbers from 10 to 2300; in this range the resistance deviates from the formula of Blasius. The lower limit of validity of the Blasius formula is determined and also the increase in resistance at the edges parallel to the flow in the case of a plate of finite width.

Interface- and discontinuity-aware numerical schemes for plasma 3-T radiation diffusion in two and three dimensions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, William W., E-mail: dai@lanl.gov; Scannapieco, Anthony J.

2015-11-01

A set of numerical schemes is developed for two- and three-dimensional time-dependent 3-T radiation diffusion equations in systems involving multi-materials. To resolve sub-cell structure, interface reconstruction is implemented within any cell that has more than one material. Therefore, the system of 3-T radiation diffusion equations is solved on two- and three-dimensional polyhedral meshes. The focus of the development is on the fully coupling between radiation and material, the treatment of nonlinearity in the equations, i.e., in the diffusion terms and source terms, treatment of the discontinuity across cell interfaces in material properties, the formulations for both transient and steady states,more » the property for large time steps, and second order accuracy in both space and time. The discontinuity of material properties between different materials is correctly treated based on the governing physics principle for general polyhedral meshes and full nonlinearity. The treatment is exact for arbitrarily strong discontinuity. The scheme is fully nonlinear for the full nonlinearity in the 3-T diffusion equations. Three temperatures are fully coupled and are updated simultaneously. The scheme is general in two and three dimensions on general polyhedral meshes. The features of the scheme are demonstrated through numerical examples for transient problems and steady states. The effects of some simplifications of numerical schemes are also shown through numerical examples, such as linearization, simple average of diffusion coefficient, and approximate treatment for the coupling between radiation and material.« less

Parallel heat transport in integrable and chaotic magnetic fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Del-Castillo-Negrete, Diego B; Chacon, Luis

2012-01-01

The study of transport in magnetized plasmas is a problem of fundamental interest in controlled fusion, space plasmas, and astrophysics research. Three issues make this problem particularly chal- lenging: (i) The extreme anisotropy between the parallel (i.e., along the magnetic field), , and the perpendicular, , conductivities ( / may exceed 1010 in fusion plasmas); (ii) Magnetic field lines chaos which in general complicates (and may preclude) the construction of magnetic field line coordinates; and (iii) Nonlocal parallel transport in the limit of small collisionality. Motivated by these issues, we present a Lagrangian Green s function method to solve themore » local and non-local parallel transport equation applicable to integrable and chaotic magnetic fields in arbitrary geom- etry. The method avoids by construction the numerical pollution issues of grid-based algorithms. The potential of the approach is demonstrated with nontrivial applications to integrable (magnetic island chain), weakly chaotic (devil s staircase), and fully chaotic magnetic field configurations. For the latter, numerical solutions of the parallel heat transport equation show that the effective radial transport, with local and non-local closures, is non-diffusive, thus casting doubts on the appropriateness of the applicability of quasilinear diffusion descriptions. General conditions for the existence of non-diffusive, multivalued flux-gradient relations in the temperature evolution are derived.« less

Effective dimensional reduction algorithm for eigenvalue problems for thin elastic structures: A paradigm in three dimensions

PubMed Central

Ovtchinnikov, Evgueni E.; Xanthis, Leonidas S.

2000-01-01

We present a methodology for the efficient numerical solution of eigenvalue problems of full three-dimensional elasticity for thin elastic structures, such as shells, plates and rods of arbitrary geometry, discretized by the finite element method. Such problems are solved by iterative methods, which, however, are known to suffer from slow convergence or even convergence failure, when the thickness is small. In this paper we show an effective way of resolving this difficulty by invoking a special preconditioning technique associated with the effective dimensional reduction algorithm (EDRA). As an example, we present an algorithm for computing the minimal eigenvalue of a thin elastic plate and we show both theoretically and numerically that it is robust with respect to both the thickness and discretization parameters, i.e. the convergence does not deteriorate with diminishing thickness or mesh refinement. This robustness is sine qua non for the efficient computation of large-scale eigenvalue problems for thin elastic structures. PMID:10655469

Comparison of diffusion length measurements from the Flying Spot Technique and the photocarrier grating method in amorphous thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vieira, M.; Fantoni, A.; Martins, R.

1994-12-31

Using the Flying Spot Technique (FST) the authors have studied minority carrier transport parallel and perpendicular to the surface of amorphous silicon films (a-Si:H). To reduce slow transients due to charge redistribution in low resistivity regions during the measurement they have applied a strong homogeneously absorbed bias light. The defect density was estimated from Constant Photocurrent Method (CPM) measurements. The steady-state photocarrier grating technique (SSPG) is a 1-dimensional approach. However, the modulation depth of the carrier profile is also dependent on film surface properties, like surface recombination velocity. Both methods yield comparable diffusion lengths when applied to a-Si:H.

Intercondylar humerus fracture- parallel plating and its results.

PubMed

Kumar, Sanjiv; Singh, Sudhir; Kumar, Dharmender; Kumar, Neeraj; Verma, Reetu

2015-01-01

Intercondylar fracture of humerus is one of the commonest fractures of young adult and counts for about 30% of all elbow fractures. The treatment of these fractures continues to present challenges despite advances in internal fixation. Although orthogonal plating use to provid adequate functional results in these fractures, parallel plating is said to be mechanically more stable construct thus allowing early mobilization and better range of motion. AIM of the study is to assess the clinical as well functional results of these fractures treated with parallel plating. Prospective study in a tertiary care hospital. A total of 23 fresh patients of intercondylar fracture of humerus from Jan 2013 to May 2014 were included in the study and were treated with parallel plating. These patients were followed at 3, 6, 12, 24 weeks and at 1year of follow up and assessed in terms of time for union, range of motion, MAYO score, DASH score and complication rate. At final follow up Mayo score was 96.32±04.96 from 5.00±01.26 and DASH SCORE was 31.42±2.04 which dropped from 150±05.34, Range of motion improved from 21.38±05.70 to 116.1±07.92 with 100% union rate and complications less than 19%. Parallel plating for intercondylar fracture of humerus is excellent method of fixation and results are similar to those treated with orthogonal plating.

An improved large-field focusing schlieren system

NASA Technical Reports Server (NTRS)

Weinstein, Leonard M.

1991-01-01

The analysis and performance of a high-brightness large-field focusing schlieren system is described. The system can be used to examine complex two- and three-dimensional flows. Techniques are described to obtain focusing schlieren through distorting optical elements, to use multiple colors in a time multiplexing technique, and to use diffuse screen holography for three-dimensional photographs.

Diffusion accessibility as a method for visualizing macromolecular surface geometry.

PubMed

Tsai, Yingssu; Holton, Thomas; Yeates, Todd O

2015-10-01

Important three-dimensional spatial features such as depth and surface concavity can be difficult to convey clearly in the context of two-dimensional images. In the area of macromolecular visualization, the computer graphics technique of ray-tracing can be helpful, but further techniques for emphasizing surface concavity can give clearer perceptions of depth. The notion of diffusion accessibility is well-suited for emphasizing such features of macromolecular surfaces, but a method for calculating diffusion accessibility has not been made widely available. Here we make available a web-based platform that performs the necessary calculation by solving the Laplace equation for steady state diffusion, and produces scripts for visualization that emphasize surface depth by coloring according to diffusion accessibility. The URL is http://services.mbi.ucla.edu/DiffAcc/. © 2015 The Protein Society.

Two-dimensional infrared spectroscopy of supercooled water.

PubMed

Perakis, Fivos; Hamm, Peter

2011-05-12

We present two-dimensional infrared (2D IR) spectra of the OD stretch vibration of isotope diluted water (HOD/H(2)O) from ambient conditions (293 K) down to the metastable supercooled regime (260 K). We observe that spectral diffusion slows down from 700 fs to 2.6 ps as we lower the temperature. A comparison between measurements performed at the magic angle with those at parallel polarization shows that the 2D IR line shape is affected by the frequency-dependent anisotropy decay in the case of parallel polarization, altering the extracted correlation decay. A fit within the framework of an Arrhenius law reveals an activation energy of E(a) = 6.2 ± 0.2 kcal/mol and a pre-exponential factor of 1/A = 0.02 ± 0.01 fs. Alternatively, a power law fit results in an exponent γ = 2.2 and a singularity temperature T(s) = 221 K. We tentatively conclude that the power law provides the better physical picture to describe the dynamics of liquid water around the freezing point.

Research in computer science

NASA Technical Reports Server (NTRS)

Ortega, J. M.

1986-01-01

Various graduate research activities in the field of computer science are reported. Among the topics discussed are: (1) failure probabilities in multi-version software; (2) Gaussian Elimination on parallel computers; (3) three dimensional Poisson solvers on parallel/vector computers; (4) automated task decomposition for multiple robot arms; (5) multi-color incomplete cholesky conjugate gradient methods on the Cyber 205; and (6) parallel implementation of iterative methods for solving linear equations.

An Integrated Approach to Parameter Learning in Infinite-Dimensional Space

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boyd, Zachary M.; Wendelberger, Joanne Roth

The availability of sophisticated modern physics codes has greatly extended the ability of domain scientists to understand the processes underlying their observations of complicated processes, but it has also introduced the curse of dimensionality via the many user-set parameters available to tune. Many of these parameters are naturally expressed as functional data, such as initial temperature distributions, equations of state, and controls. Thus, when attempting to find parameters that match observed data, being able to navigate parameter-space becomes highly non-trivial, especially considering that accurate simulations can be expensive both in terms of time and money. Existing solutions include batch-parallel simulations,more » high-dimensional, derivative-free optimization, and expert guessing, all of which make some contribution to solving the problem but do not completely resolve the issue. In this work, we explore the possibility of coupling together all three of the techniques just described by designing user-guided, batch-parallel optimization schemes. Our motivating example is a neutron diffusion partial differential equation where the time-varying multiplication factor serves as the unknown control parameter to be learned. We find that a simple, batch-parallelizable, random-walk scheme is able to make some progress on the problem but does not by itself produce satisfactory results. After reducing the dimensionality of the problem using functional principal component analysis (fPCA), we are able to track the progress of the solver in a visually simple way as well as viewing the associated principle components. This allows a human to make reasonable guesses about which points in the state space the random walker should try next. Thus, by combining the random walker's ability to find descent directions with the human's understanding of the underlying physics, it is possible to use expensive simulations more efficiently and more quickly arrive at the desired parameter set.« less

Omni-directional railguns

DOEpatents

Shahinpoor, Mohsen

1995-01-01

A device for electromagnetically accelerating projectiles. The invention features two parallel conducting circular plates, a plurality of electrode connections to both upper and lower plates, a support base, and a projectile magazine. A projectile is spring-loaded into a firing position concentrically located between the parallel plates. A voltage source is applied to the plates to cause current to flow in directions defined by selectable, discrete electrode connections on both upper and lower plates. Repulsive Lorentz forces are generated to eject the projectile in a 360 degree range of fire.

A position sensitive microchannel photomultiplier for ultraviolet space astronomy

NASA Technical Reports Server (NTRS)

Lampton, M.; Siegmund, O. H. W.; Bixler, J.; Bowyer, S.

1986-01-01

The 25-mm microchannel-plate, position-sensitive UV astronomy photomultiplier tube presented is intended for the EOM-1 Spacelab Mission's FAUST payload and conducts wide-field imaging surveys in the VUV over the 1400-1800-A range. The sealed detector encompasses a CsI photocathode deposited on the inner surface of a MgF2 window, a stack of microchannel plates, and a wedge-and-strip two-dimensional position-sensing anode. Since the wedge-and-strip principle requires only three anode signals, flight electronics can be reduced to three charge amplifiers and three analog-to-digital converters.

The development of a three-dimensional partially elliptic flow computer program for combustor research

NASA Technical Reports Server (NTRS)

Pan, Y. S.

1978-01-01

A three dimensional, partially elliptic, computer program was developed. Without requiring three dimensional computer storage locations for all flow variables, the partially elliptic program is capable of predicting three dimensional combustor flow fields with large downstream effects. The program requires only slight increase of computer storage over the parabolic flow program from which it was developed. A finite difference formulation for a three dimensional, fully elliptic, turbulent, reacting, flow field was derived. Because of the negligible diffusion effects in the main flow direction in a supersonic combustor, the set of finite-difference equations can be reduced to a partially elliptic form. Only the pressure field was governed by an elliptic equation and requires three dimensional storage; all other dependent variables are governed by parabolic equations. A numerical procedure which combines a marching integration scheme with an iterative scheme for solving the elliptic pressure was adopted.

[Meta analysis of parallel versus perpendicular double plating for distal humerus fracture of type C in adults].

PubMed

Li, B B; Lin, F; Cai, L H; Chen, Y; Lin, Z J

2017-08-01

Objective: To evaluate the effects of parallel versus perpendicular double plating for distal humerus fracture of type C. Methods: A standardized comprehensive literature search was performed by PubMed, Embase, Cochrane library, CMB, CNKI and Medline datebase.Randomized controlled studies on comparison between parallel versus perpendicular double plating for distal humerus fracture of type C before December 2015 were enrolled in the study.All date were analyzed by the RevMan 5.2 software. Results: Six studies, including 284 patients, met the inclusion criteria.There were 155 patients in perpendicular double plating group, 129 patients in parallel double plating group.The results of Meta-analysis indicated that there were statistically significant difference between the two groups in complications ( OR =2.59, 95% CI : 1.03 to 6.53, P =0.04). There was no significant difference between the two groups in surgical duration ( MD =-1.84, 95% CI : -9.06 to 5.39, P =0.62), bone union time ( MD =0.09, 95% CI : -0.06 to 0.24, P =0.22), Mayo Elbow Performance Score ( MD =0.09, 95% CI : -0.06 to 0.24, P =0.22), Range of Motions ( MD =-0.92, 95% CI : -4.65 to 2.81, P =0.63) and the rate of excellent and good results ( OR =0.64, 95% CI : 0.27 to 1.52, P =0.31). Conclusion: Both perpendicular and parallel double plating are effective in distal humerus fracture of type C, parallel double plating has less complications.

Stress measurement in thick plates using nonlinear ultrasonics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abbasi, Zeynab, E-mail: zabbas5@uic.edu, E-mail: dozevin@uic.edu; Ozevin, Didem, E-mail: zabbas5@uic.edu, E-mail: dozevin@uic.edu

2015-03-31

In this paper the interaction between nonlinear ultrasonic characteristics and stress state of complex loaded thick steel plates using fundamental theory of nonlinear ultrasonics is investigated in order to measure the stress state at a given cross section. The measurement concept is based on phased array placement of ultrasonic transmitter-receiver to scan three angles of a given cross section using Rayleigh waves. The change in the ultrasonic data in thick steel plates is influenced by normal and shear stresses; therefore, three measurements are needed to solve the equations simultaneously. Different thickness plates are studied in order to understand the interactionmore » of Rayleigh wave penetration depth and shear stress. The purpose is that as the thickness becomes smaller, the shear stress becomes negligible at the angled measurement. For thicker cross section, shear stress becomes influential if the depth of penetration of Rayleigh wave is greater than the half of the thickness. The influences of plate thickness and ultrasonic frequency on the identification of stress tensor are numerically studied in 3D structural geometry and Murnaghan material model. The experimental component of this study includes uniaxial loading of the plate while measuring ultrasonic wave at three directions (perpendicular, parallel and angled to the loading direction). Instead of rotating transmitter-receiver pair for each test, a device capable of measuring the three angles is designed.« less

Efficacy of 3-Dimensional plates over Champys miniplates in mandibular anterior fractures

PubMed Central

Barde, Dhananjay H; Mudhol, Anupama; Ali, Fareedi Mukram; Madan, R S; Kar, Sanjay; Ustaad, Farheen

2014-01-01

Background: Mandibular fractures are treated surgically by either rigid or semi-rigid fixation, two techniques that reflect almost opposite concept of craniomaxillofacial osteosynthesis. The shortcomings of these fixations led to the development of 3 dimensional (3D) miniplates. This study was designed with the aim of evaluating the efficiency of 3D miniplate over Champys miniplate in anterior mandibular fractures. Materials & Methods: This study was done in 40 patients with anterior mandibular fractures. Group I consisting of 20 patients in whom 3D plates were used for fixation while in Group II consisting of other 20 patients, 4 holes straight plates were used. The efficacy of 3D miniplate over Champy’s miniplate was evaluated in terms of operating time, average pain, post operative infection, occlusion, wound dehiscence, post operative mobility and neurological deficit. Results: The mean operation time for Group II was more compared to Group I (statistically significant).There was significantly greater pain on day of surgery and at 2nd week for Group II patients but there was no significant difference between the two groups at 4th week. The post operative infection, occlusal disturbance, wound dehiscence, post operative mobility at facture site, neurological deficit was statistically insignificant (chi square test). Conclusion: The results of this study suggest that fixation of anterior mandibular fractures with 3D plates provides three dimensional stability and carries low morbidity and infection rates. The only probable limitation of these 3D plates may be excessive implant material, but they seem to be easy alternative to champys miniplate. How to cite the article: Barde DH, Mudhol A, Ali FM, Madan RS, Kar S, Ustaad F. Efficacy of 3-Dimensional plates over Champys miniplates in mandibular anterior fractures. J Int Oral Health 2014;6(1):20-6. PMID:24653598

A numerical study of incompressible juncture flows

NASA Technical Reports Server (NTRS)

Kwak, D.; Rogers, S. E.; Kaul, U. K.; Chang, J. L. C.

1986-01-01

The laminar, steady juncture flow around single or multiple posts mounted between two flat plates is simulated using the three dimensional incompressible Navier-Stokes code, INS3D. The three dimensional separation of the boundary layer and subsequent formation and development of the horseshoe vortex is computed. The computed flow compares favorably with the experimental observation. The recent numerical study to understand and quantify the juncture flow relevant to the Space Shuttle main engine power head is summarized.

Tumor cell culture on collagen-chitosan scaffolds as three-dimensional tumor model: A suitable model for tumor studies.

PubMed

Mahmoudzadeh, Aziz; Mohammadpour, Hemn

2016-07-01

Tumor cells naturally live in three-dimensional (3D) microenvironments, while common laboratory tests and evaluations are done in two-dimensional (2D) plates. This study examined the impact of cultured 4T1 cancer cells in a 3D collagen-chitosan scaffold compared with 2D plate cultures. Collagen-chitosan scaffolds were provided and passed confirmatory tests. 4T1 tumor cells were cultured on scaffolds and then tumor cells growth rate, resistance to X-ray radiation, and cyclophosphamide as a chemotherapy drug were analyzed. Furthermore, 4T1 cells were extracted from the scaffold model and were injected into the mice. Tumor growth rate, survival rate, and systemic immune responses were evaluated. Our results showed that 4T1 cells infiltrated the scaffolds pores and constructed a 3D microenvironment. Furthermore, 3D cultured tumor cells showed a slower proliferation rate, increased levels of survival to the X-ray irradiation, and enhanced resistance to chemotherapy drugs in comparison with 2D plate cultures. Transfer of extracted cells to the mice caused enhanced tumor volume and decreased life span. This study indicated that collagen-chitosan nanoscaffolds provide a suitable model of tumor that would be appropriate for tumor studies. Copyright © 2016. Published by Elsevier B.V.

Study of Lamb Waves for Non-Destructive Testing Behind Screens

NASA Astrophysics Data System (ADS)

Kauffmann, P.; Ploix, M.-A.; Chaix, J.-F.; Gueudré, C.; Corneloup, G.; Baqué, F. AF(; )

2018-01-01

The inspection and control of sodium-cooled fast reactors (SFR) is a major issue for the nuclear industry. Ultrasonic solutions are under study because of the opacity of liquid sodium. In this paper, the use of leaky Lamb waves is considered for non-destructive testing (NDT) on parallel and immersed structures assimilated as plates. The first phase of our approach involved studying the propagation properties of leaky Lamb waves. Equations that model the propagation of Lamb waves in an immersed plate were solved numerically. The phase velocity can be experimentally measured using a two dimensional Fourier transform. The group velocity can be experimentally measured using a short-time Fourier transform technique. Attenuation of leaky Lamb waves is mostly due to the re-emission of energy into the surrounding fluid, and it can be measured by these two techniques.

Computational Performance of a Parallelized Three-Dimensional High-Order Spectral Element Toolbox

NASA Astrophysics Data System (ADS)

Bosshard, Christoph; Bouffanais, Roland; Clémençon, Christian; Deville, Michel O.; Fiétier, Nicolas; Gruber, Ralf; Kehtari, Sohrab; Keller, Vincent; Latt, Jonas

In this paper, a comprehensive performance review of an MPI-based high-order three-dimensional spectral element method C++ toolbox is presented. The focus is put on the performance evaluation of several aspects with a particular emphasis on the parallel efficiency. The performance evaluation is analyzed with help of a time prediction model based on a parameterization of the application and the hardware resources. A tailor-made CFD computation benchmark case is introduced and used to carry out this review, stressing the particular interest for clusters with up to 8192 cores. Some problems in the parallel implementation have been detected and corrected. The theoretical complexities with respect to the number of elements, to the polynomial degree, and to communication needs are correctly reproduced. It is concluded that this type of code has a nearly perfect speed up on machines with thousands of cores, and is ready to make the step to next-generation petaflop machines.

Synchronized Molecular-Dynamics simulation for thermal lubrication of a polymeric liquid between parallel plates

NASA Astrophysics Data System (ADS)

Yasuda, Shugo; Yamamoto, Ryoichi

2015-11-01

The Synchronized Molecular-Dynamics simulation which was recently proposed by authors is applied to the analysis of polymer lubrication between parallel plates. In the SMD method, the MD simulations are assigned to small fluid elements to calculate the local stresses and temperatures and are synchronized at certain time intervals to satisfy the macroscopic heat- and momentum-transport equations.The rheological properties and conformation of the polymer chains coupled with local viscous heating are investigated with a non-dimensional parameter, the Nahme-Griffith number, which is defined as the ratio of the viscous heating to the thermal conduction at the characteristic temperature required to sufficiently change the viscosity. The present simulation demonstrates that strong shear thinning and a transitional behavior of the conformation of the polymer chains are exhibited with a rapid temperature rise when the Nahme-Griffith number exceeds unity.The results also clarify that the reentrant transition of the linear stress-optical relation occurs for large shear stresses due to the coupling of the conformation of polymer chains with heat generation under shear flows. This study was financially supported by JSPS KAKENHI Grant Nos. 26790080 and 26247069.

Distal radius osteotomy with volar locking plates based on computer simulation.

PubMed

Miyake, Junichi; Murase, Tsuyoshi; Moritomo, Hisao; Sugamoto, Kazuomi; Yoshikawa, Hideki

2011-06-01

Corrective osteotomy using dorsal plates and structural bone graft usually has been used for treating symptomatic distal radius malunions. However, the procedure is technically demanding and requires an extensive dorsal approach. Residual deformity is a relatively frequent complication of this technique. We evaluated the clinical applicability of a three-dimensional osteotomy using computer-aided design and manufacturing techniques with volar locking plates for distal radius malunions. Ten patients with metaphyseal radius malunions were treated. Corrective osteotomy was simulated with the help of three-dimensional bone surface models created using CT data. We simulated the most appropriate screw holes in the deformed radius using computer-aided design data of a locking plate. During surgery, using a custom-made surgical template, we predrilled the screw holes as simulated. After osteotomy, plate fixation using predrilled screw holes enabled automatic reduction of the distal radial fragment. Autogenous iliac cancellous bone was grafted after plate fixation. The median volar tilt, radial inclination, and ulnar variance improved from -20°, 13°, and 6 mm, respectively, before surgery to 12°, 24°, and 1 mm, respectively, after surgery. The median wrist flexion improved from 33° before surgery to 60° after surgery. The median wrist extension was 70° before surgery and 65° after surgery. All patients experienced wrist pain before surgery, which disappeared or decreased after surgery. Surgeons can operate precisely and easily using this advanced technique. It is a new treatment option for malunion of distal radius fractures.

Numerical Test of Analytical Theories for Perpendicular Diffusion in Small Kubo Number Turbulence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heusen, M.; Shalchi, A., E-mail: husseinm@myumanitoba.ca, E-mail: andreasm4@yahoo.com

In the literature, one can find various analytical theories for perpendicular diffusion of energetic particles interacting with magnetic turbulence. Besides quasi-linear theory, there are different versions of the nonlinear guiding center (NLGC) theory and the unified nonlinear transport (UNLT) theory. For turbulence with high Kubo numbers, such as two-dimensional turbulence or noisy reduced magnetohydrodynamic turbulence, the aforementioned nonlinear theories provide similar results. For slab and small Kubo number turbulence, however, this is not the case. In the current paper, we compare different linear and nonlinear theories with each other and test-particle simulations for a noisy slab model corresponding to smallmore » Kubo number turbulence. We show that UNLT theory agrees very well with all performed test-particle simulations. In the limit of long parallel mean free paths, the perpendicular mean free path approaches asymptotically the quasi-linear limit as predicted by the UNLT theory. For short parallel mean free paths we find a Rechester and Rosenbluth type of scaling as predicted by UNLT theory as well. The original NLGC theory disagrees with all performed simulations regardless what the parallel mean free path is. The random ballistic interpretation of the NLGC theory agrees much better with the simulations, but compared to UNLT theory the agreement is inferior. We conclude that for this type of small Kubo number turbulence, only the latter theory allows for an accurate description of perpendicular diffusion.« less

Effects of 3 dimensional crystal geometry and orientation on 1D and 2D time-scale determinations of magmatic processes using olivine and orthopyroxene

NASA Astrophysics Data System (ADS)

Shea, Thomas; Krimer, Daniel; Costa, Fidel; Hammer, Julia

2014-05-01

One of the achievements in recent years in volcanology is the determination of time-scales of magmatic processes via diffusion in minerals and its addition to the petrologists' and volcanologists' toolbox. The method typically requires one-dimensional modeling of randomly cut crystals from two-dimensional thin sections. Here we address the question whether using 1D (traverse) or 2D (surface) datasets exploited from randomly cut 3D crystals introduces a bias or dispersion in the time-scales estimated, and how this error can be improved or eliminated. Computational simulations were performed using a concentration-dependent, finite-difference solution to the diffusion equation in 3D. The starting numerical models involved simple geometries (spheres, parallelepipeds), Mg/Fe zoning patterns (either normal or reverse), and isotropic diffusion coefficients. Subsequent models progressively incorporated more complexity, 3D olivines possessing representative polyhedral morphologies, diffusion anisotropy along the different crystallographic axes, and more intricate core-rim zoning patterns. Sections and profiles used to compare 1, 2 and 3D diffusion models were selected to be (1) parallel to the crystal axes, (2) randomly oriented but passing through the olivine center, or (3) randomly oriented and sectioned. Results show that time-scales estimated on randomly cut traverses (1D) or surfaces (2D) can be widely distributed around the actual durations of 3D diffusion (~0.2 to 10 times the true diffusion time). The magnitude over- or underestimations of duration are a complex combination of the geometry of the crystal, the zoning pattern, the orientation of the cuts with respect to the crystallographic axes, and the degree of diffusion anisotropy. Errors on estimated time-scales retrieved from such models may thus be significant. Drastic reductions in the uncertainty of calculated diffusion times can be obtained by following some simple guidelines during the course of data collection (i.e. selection of crystals and concentration profiles, acquisition of crystallographic orientation data), thus allowing derivation of robust time-scales.

A Novel Computer-Aided Approach for Parametric Investigation of Custom Design of Fracture Fixation Plates.

PubMed

Chen, Xiaozhong; He, Kunjin; Chen, Zhengming

2017-01-01

The present study proposes an integrated computer-aided approach combining femur surface modeling, fracture evidence recover plate creation, and plate modification in order to conduct a parametric investigation of the design of custom plate for a specific patient. The study allows for improving the design efficiency of specific plates on the patients' femur parameters and the fracture information. Furthermore, the present approach will lead to exploration of plate modification and optimization. The three-dimensional (3D) surface model of a detailed femur and the corresponding fixation plate were represented with high-level feature parameters, and the shape of the specific plate was recursively modified in order to obtain the optimal plate for a specific patient. The proposed approach was tested and verified on a case study, and it could be helpful for orthopedic surgeons to design and modify the plate in order to fit the specific femur anatomy and the fracture information.

Investigating the Role of Surface Materials and Three Dimensional Architecture on In Vitro Differentiation of Porcine Monocyte-Derived Dendritic Cells

PubMed Central

Hartmann, Sofie Bruun; Mohanty, Soumyaranjan; Skovgaard, Kerstin; Brogaard, Louise; Flagstad, Frederikke Bjergvang; Emnéus, Jenny; Wolff, Anders; Summerfield, Artur; Jungersen, Gregers

2016-01-01

In vitro generation of dendritic-like cells through differentiation of peripheral blood monocytes is typically done using two-dimensional polystyrene culture plates. In the process of optimising cell culture techniques, engineers have developed fluidic micro-devises usually manufactured in materials other than polystyrene and applying three-dimensional structures more similar to the in vivo environment. Polydimethylsiloxane (PDMS) is an often used polymer for lab-on-a-chip devices but not much is known about the effect of changing the culture surface material from polystyrene to PDMS. In the present study the differentiation of porcine monocytes to monocyte-derived dendritic cells (moDCs) was investigated using CD172apos pig blood monocytes stimulated with GM-CSF and IL-4. Monocytes were cultured on surfaces made of two- and three-dimensional polystyrene as well as two- and three-dimensional PDMS and carbonised three-dimensional PDMS. Cells cultured conventionally (on two-dimensional polystyrene) differentiated into moDCs as expected. Interestingly, gene expression of a wide range of cytokines, chemokines, and pattern recognition receptors was influenced by culture surface material and architecture. Distinct clustering of cells, based on similar expression patterns of 46 genes of interest, was seen for cells isolated from two- and three-dimensional polystyrene as well as two- and three-dimensional PDMS. Changing the material from polystyrene to PDMS resulted in cells with expression patterns usually associated with macrophage expression (upregulation of CD163 and downregulation of CD1a, FLT3, LAMP3 and BATF3). However, this was purely based on gene expression level, and no functional assays were included in this study which would be necessary in order to classify the cells as being macrophages. When changing to three-dimensional culture the cells became increasingly activated in terms of IL6, IL8, IL10 and CCR5 gene expression. Further stimulation with LPS resulted in a slight increase in the expression of maturation markers (SLA-DRB1, CD86 and CD40) as well as cytokines (IL6, IL8, IL10 and IL23A) but the influence of the surfaces was unchanged. These findings highlights future challenges of combining and comparing data generated from microfluidic cell culture-devices made using alternative materials to data generated using conventional polystyrene plates used by most laboratories today. PMID:27362493

Investigating the Role of Surface Materials and Three Dimensional Architecture on In Vitro Differentiation of Porcine Monocyte-Derived Dendritic Cells.

PubMed

Hartmann, Sofie Bruun; Mohanty, Soumyaranjan; Skovgaard, Kerstin; Brogaard, Louise; Flagstad, Frederikke Bjergvang; Emnéus, Jenny; Wolff, Anders; Summerfield, Artur; Jungersen, Gregers

2016-01-01

In vitro generation of dendritic-like cells through differentiation of peripheral blood monocytes is typically done using two-dimensional polystyrene culture plates. In the process of optimising cell culture techniques, engineers have developed fluidic micro-devises usually manufactured in materials other than polystyrene and applying three-dimensional structures more similar to the in vivo environment. Polydimethylsiloxane (PDMS) is an often used polymer for lab-on-a-chip devices but not much is known about the effect of changing the culture surface material from polystyrene to PDMS. In the present study the differentiation of porcine monocytes to monocyte-derived dendritic cells (moDCs) was investigated using CD172apos pig blood monocytes stimulated with GM-CSF and IL-4. Monocytes were cultured on surfaces made of two- and three-dimensional polystyrene as well as two- and three-dimensional PDMS and carbonised three-dimensional PDMS. Cells cultured conventionally (on two-dimensional polystyrene) differentiated into moDCs as expected. Interestingly, gene expression of a wide range of cytokines, chemokines, and pattern recognition receptors was influenced by culture surface material and architecture. Distinct clustering of cells, based on similar expression patterns of 46 genes of interest, was seen for cells isolated from two- and three-dimensional polystyrene as well as two- and three-dimensional PDMS. Changing the material from polystyrene to PDMS resulted in cells with expression patterns usually associated with macrophage expression (upregulation of CD163 and downregulation of CD1a, FLT3, LAMP3 and BATF3). However, this was purely based on gene expression level, and no functional assays were included in this study which would be necessary in order to classify the cells as being macrophages. When changing to three-dimensional culture the cells became increasingly activated in terms of IL6, IL8, IL10 and CCR5 gene expression. Further stimulation with LPS resulted in a slight increase in the expression of maturation markers (SLA-DRB1, CD86 and CD40) as well as cytokines (IL6, IL8, IL10 and IL23A) but the influence of the surfaces was unchanged. These findings highlights future challenges of combining and comparing data generated from microfluidic cell culture-devices made using alternative materials to data generated using conventional polystyrene plates used by most laboratories today.

Near Earth Asteroid Scout Solar Sail Thrust and Torque Model

NASA Technical Reports Server (NTRS)

Heaton, Andy; Ahmad, Naeem; Miller, Kyle

2017-01-01

The Near Earth Asteroid (NEA) Scout is a solar sail mission whose objective is to scout at least one Near Earth Asteroid to help prepare for human missions to Near Earth Asteroids. NEA Scout will launch as a secondary payload on the first SLS-Orion mission. NEA Scout will perform a small trim maneuver shortly after deploy from the spent SLS upper stage using a cold gas propulsion system, but from that point on will depend entirely on the solar sail for thrust. As such, it is important to accurately characterize the thrust of the sail in order to achieve mission success. Additionally, the solar sail creates a relatively large solar disturbance torque that must be mitigated. For early mission design studies a flat plate model of the solar sail with a fixed center of pressure was adequate, but as mission concepts and the sail design matured, greater fidelity was required. Here we discuss the progress to a three-dimensional sail model that includes the effects of tension and thermal deformation that has been derived from a large structural Finite Element Model (FEM) developed by the Langley Research Center. We have found that the deformed sail membrane affects torque relatively much more than thrust; a flat plate model could potentially model thrust well enough to close mission design studies, but a three-dimensional solar sail is essential to control system design. The three-dimensional solar sail model revealed that thermal deformations of unshielded booms would create unacceptably large solar disturbance torques. The original large FEM model was used in control and mission simulations, but was resulted in simulations with prohibitive run times. This led us to adapt the Generalized Sail Model (GSM) of Rios-Reyes. A design reference sail model has been baselined for NEA Scout and has been used to design the mission and control system for the sailcraft. Additionally, since NEA Scout uses reaction wheels for attitude pointing and control, the solar torque model is essentially to successfully design the NEA Scout momentum management control system. We have also updated the estimate of diffusivity used for the aluminized sail material based on optical testing of wrinkled sail material. The model presented here represents the current state of the art of NASA's ability to model solar sail thrust and torque.

Plate tectonics on the Earth triggered by plume-induced subduction initiation.

PubMed

Gerya, T V; Stern, R J; Baes, M; Sobolev, S V; Whattam, S A

2015-11-12

Scientific theories of how subduction and plate tectonics began on Earth--and what the tectonic structure of Earth was before this--remain enigmatic and contentious. Understanding viable scenarios for the onset of subduction and plate tectonics is hampered by the fact that subduction initiation processes must have been markedly different before the onset of global plate tectonics because most present-day subduction initiation mechanisms require acting plate forces and existing zones of lithospheric weakness, which are both consequences of plate tectonics. However, plume-induced subduction initiation could have started the first subduction zone without the help of plate tectonics. Here, we test this mechanism using high-resolution three-dimensional numerical thermomechanical modelling. We demonstrate that three key physical factors combine to trigger self-sustained subduction: (1) a strong, negatively buoyant oceanic lithosphere; (2) focused magmatic weakening and thinning of lithosphere above the plume; and (3) lubrication of the slab interface by hydrated crust. We also show that plume-induced subduction could only have been feasible in the hotter early Earth for old oceanic plates. In contrast, younger plates favoured episodic lithospheric drips rather than self-sustained subduction and global plate tectonics.

Computing Shapes Of Cascade Diffuser Blades

NASA Technical Reports Server (NTRS)

Tran, Ken; Prueger, George H.

1993-01-01

Computer program generates sizes and shapes of cascade-type blades for use in axial or radial turbomachine diffusers. Generates shapes of blades rapidly, incorporating extensive cascade data to determine optimum incidence and deviation angle for blade design based on 65-series data base of National Advisory Commission for Aeronautics and Astronautics (NACA). Allows great variability in blade profile through input variables. Also provides for design of three-dimensional blades by allowing variable blade stacking. Enables designer to obtain computed blade-geometry data in various forms: as input for blade-loading analysis; as input for quasi-three-dimensional analysis of flow; or as points for transfer to computer-aided design.

A Galerkin approximation for linear elastic shallow shells

NASA Astrophysics Data System (ADS)

Figueiredo, I. N.; Trabucho, L.

1992-03-01

This work is a generalization to shallow shell models of previous results for plates by B. Miara (1989). Using the same basis functions as in the plate case, we construct a Galerkin approximation of the three-dimensional linearized elasticity problem, and establish some error estimates as a function of the thickness, the curvature, the geometry of the shell, the forces and the Lamé costants.

Feasibility of creating a high-resolution 3D diffusion tensor imaging based atlas of the human brainstem: A case study at 11.7T

PubMed Central

Aggarwal, Manisha; Zhang, Jiangyang; Pletnikova, Olga; Crain, Barbara; Troncoso, Juan; Mori, Susumu

2013-01-01

A three-dimensional stereotaxic atlas of the human brainstem based on high resolution ex vivo diffusion tensor imaging (DTI) is introduced. The atlas consists of high resolution (125–255 μm isotropic) three-dimensional DT images of the formalin-fixed brainstem acquired at 11.7T. The DTI data revealed microscopic neuroanatomical details, allowing three-dimensional visualization and reconstruction of fiber pathways including the decussation of the pyramidal tract fibers, and interdigitating fascicles of the corticospinal and transverse pontine fibers. Additionally, strong grey-white matter contrasts in the apparent diffusion coefficient (ADC) maps enabled precise delineation of grey matter nuclei in the brainstem, including the cranial nerve and the inferior olivary nuclei. Comparison with myelin-stained histology shows that at the level of resolution achieved in this study, the structural details resolved with DTI contrasts in the brainstem were comparable to anatomical delineation obtained with histological sectioning. Major neural structures delineated from DTI contrasts in the brainstem are segmented and three-dimensionally reconstructed. Further, the ex vivo DTI data are nonlinearly mapped to a widely-used in vivo human brain atlas, to construct a high-resolution atlas of the brainstem in the Montreal Neurological Institute (MNI) stereotaxic coordinate space. The results demonstrate the feasibility of developing a 3D DTI based atlas for detailed characterization of brainstem neuroanatomy with high resolution and contrasts, which will be a useful resource for research and clinical applications. PMID:23384518

Temperature field determination in slabs, circular plates and spheres with saw tooth heat generating sources

NASA Astrophysics Data System (ADS)

Diestra Cruz, Heberth Alexander

The Green's functions integral technique is used to determine the conduction heat transfer temperature field in flat plates, circular plates, and solid spheres with saw tooth heat generating sources. In all cases the boundary temperature is specified (Dirichlet's condition) and the thermal conductivity is constant. The method of images is used to find the Green's function in infinite solids, semi-infinite solids, infinite quadrants, circular plates, and solid spheres. The saw tooth heat generation source has been modeled using Dirac delta function and Heaviside step function. The use of Green's functions allows obtain the temperature distribution in the form of an integral that avoids the convergence problems of infinite series. For the infinite solid and the sphere, the temperature distribution is three-dimensional and in the cases of semi-infinite solid, infinite quadrant and circular plate the distribution is two-dimensional. The method used in this work is superior to other methods because it obtains elegant analytical or quasi-analytical solutions to complex heat conduction problems with less computational effort and more accuracy than the use of fully numerical methods.

Cooled particle accelerator target

DOEpatents

Degtiarenko, Pavel V.

2005-06-14

A novel particle beam target comprising: a rotating target disc mounted on a retainer and thermally coupled to a first array of spaced-apart parallel plate fins that extend radially inwardly from the retainer and mesh without physical contact with a second array of spaced-apart parallel plate fins that extend radially outwardly from and are thermally coupled to a cooling mechanism capable of removing heat from said second array of spaced-apart fins and located within the first array of spaced-apart parallel fins. Radiant thermal exchange between the two arrays of parallel plate fins provides removal of heat from the rotating disc. A method of cooling the rotating target is also described.

Use of gamma ray radiation to parallel the plates of a Fabry-Perot interferometer

NASA Technical Reports Server (NTRS)

Skinner, Wilbert R.; Hays, Paul B.; Anderson, Sally M.

1987-01-01

The use of gamma radiation to parallel the plates of a Fabry-Perot etalon is examined. The method for determining the etalon parallelism, and the procedure for irradiating the posts are described. Changes in effective gap for the etalon over the surface are utilized to measure the parallelism of the Fabry-Perot etalon. An example in which this technique is applied to an etalon of fused silica plates, which are 132 mm in diameter and coded with zinc sulfide and cryolite, with Zerodur spaces 2 cm in length. The effect of the irradiation of the posts on the thermal performance of the etalon is investigated.

Visualization of the contact line during the water exit of flat plates

NASA Astrophysics Data System (ADS)

Tassin, A.; Breton, T.; Forest, B.; Ohana, J.; Chalony, S.; Le Roux, D.; Tancray, A.

2017-08-01

We investigate experimentally the time evolution of the wetted surface during the lifting of a body initially floating at the water surface. This phenomenon is referred to as the water exit problem. The water exit experiments were conducted with transparent (PMMA) mock-ups of two different shapes: a circular disc and a square flat plate. Two different lighting systems were used to diffuse light in the mock-up material: a central high-power LED light normal to the surface and an edge-lighting system featuring an array of LED lights. These setups make it possible to illuminate the contact line, which delimits the surface of contact between the mock-up and the water. The characteristic size of the mock-ups is about 20 cm and the acceleration of the mock-up oscillates between 0 and 25 m/s^2. We show that the central light setup gives satisfactory results for the circular disc and that the edge lighting technique makes it possible to follow a contact line with a time-evolving complex shape (strong changes of convexity) up to 1000 fps. The observations presented in the paper support the possibility of extending this promising technique to more general three-dimensional bodies with arbitrary motion (e.g., including pitch motion).

Investigation of the oxygen exchange mechanism on Pt|yttria stabilized zirconia at intermediate temperatures: Surface path versus bulk path

PubMed Central

Opitz, Alexander K.; Lutz, Alexander; Kubicek, Markus; Kubel, Frank; Hutter, Herbert; Fleig, Jürgen

2011-01-01

The oxygen exchange kinetics of platinum on yttria-stabilized zirconia (YSZ) was investigated by means of geometrically well-defined Pt microelectrodes. By variation of electrode size and temperature it was possible to separate two temperature regimes with different geometry dependencies of the polarization resistance. At higher temperatures (550–700 °C) an elementary step located close to the three phase boundary (TPB) with an activation energy of ∼1.6 eV was identified as rate limiting. At lower temperatures (300–400 °C) the rate limiting elementary step is related to the electrode area and exhibited a very low activation energy in the order of 0.2 eV. From these observations two parallel pathways for electrochemical oxygen exchange are concluded. The nature of these two elementary steps is discussed in terms of equivalent circuits. Two combinations of parallel rate limiting reaction steps are found to explain the observed geometry dependencies: (i) Diffusion through an impurity phase at the TPB in parallel to diffusion of oxygen through platinum – most likely along Pt grain boundaries – as area-related process. (ii) Co-limitation of oxygen diffusion along the Pt|YSZ interface and charge transfer at the interface with a short decay length of the corresponding transmission line (as TPB-related process) in parallel to oxygen diffusion through platinum. PMID:22210951

Performance of a three-dimensional Navier-Stokes code on CYBER 205 for high-speed juncture flows

NASA Technical Reports Server (NTRS)

Lakshmanan, B.; Tiwari, S. N.

1987-01-01

A vectorized 3D Navier-Stokes code has been implemented on CYBER 205 for solving the supersonic laminar flow over a swept fin/flat plate junction. The code extends MacCormack's predictor-corrector finite volume scheme to a generalized coordinate system in a locally one dimensional time split fashion. A systematic parametric study is conducted to examine the effect of fin sweep on the computed flow field. Calculated results for the pressure distribution on the flat plate and fin leading edge are compared with the experimental measurements of a right angle blunt fin/flat plate junction. The decrease in the extent of the separated flow region and peak pressure on the fin leading edge, and weakening of the two reversed supersonic zones with increase in fin sweep have been clearly observed in the numerical simulation.

Accuracy of impressions with different impression materials in angulated implants.

PubMed

Reddy, S; Prasad, K; Vakil, H; Jain, A; Chowdhary, R

2013-01-01

To evaluate the dimensional accuracy of the resultant (duplicative) casts made from two different impression materials (polyvinyl siloxane and polyether) in parallel and angulated implants. Three definitive master casts (control groups) were fabricated in dental stone with three implants, placed at equi-distance. In first group (control), all three implants were placed parallel to each other and perpendicular to the plane of the cast. In the second and third group (control), all three implants were placed at 10° and 15 o angulation respectively to the long axis of the cast, tilting towards the centre. Impressions were made with polyvinyl siloxane and polyether impression materials in a special tray, using a open tray impression technique from the master casts. These impressions were poured to obtain test casts. Three reference distances were evaluated on each test cast by using a profile projector and compared with control groups to determine the effect of combined interaction of implant angulation and impression materials on the accuracy of implant resultant cast. Statistical analysis revealed no significant difference in dimensional accuracy of the resultant casts made from two different impression materials (polyvinyl siloxane and polyether) by closed tray impression technique in parallel and angulated implants. On the basis of the results of this study, the use of both the impression materials i.e., polyether and polyvinyl siloxane impression is recommended for impression making in parallel as well as angulated implants.

Landmark-based elastic registration using approximating thin-plate splines.

PubMed

Rohr, K; Stiehl, H S; Sprengel, R; Buzug, T M; Weese, J; Kuhn, M H

2001-06-01

We consider elastic image registration based on a set of corresponding anatomical point landmarks and approximating thin-plate splines. This approach is an extension of the original interpolating thin-plate spline approach and allows to take into account landmark localization errors. The extension is important for clinical applications since landmark extraction is always prone to error. Our approach is based on a minimizing functional and can cope with isotropic as well as anisotropic landmark errors. In particular, in the latter case it is possible to include different types of landmarks, e.g., unique point landmarks as well as arbitrary edge points. Also, the scheme is general with respect to the image dimension and the order of smoothness of the underlying functional. Optimal affine transformations as well as interpolating thin-plate splines are special cases of this scheme. To localize landmarks we use a semi-automatic approach which is based on three-dimensional (3-D) differential operators. Experimental results are presented for two-dimensional as well as 3-D tomographic images of the human brain.

MTR plates modeling with MAIA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marelle, V.; Dubois, S.; Ripert, M.

2008-07-15

MAIA is a thermo-mechanical code dedicated to the modeling of MTR fuel plates. The main physical phenomena modeled in the code are the cladding oxidation, the interaction between fuel and Al-matrix, the swelling due to fission products and the Al/fuel particles interaction. The creeping of the plate can be modeled in the mechanical calculation. MAIA has been validated on U-Mo dispersion fuel experiments such as IRIS 1 and 2 and FUTURE. The results are in rather good agreement with post-irradiation examinations. MAIA can also be used to calculate in-pile behavior of U{sub 3}Si{sub 2} plates as in the SHARE experimentmore » irradiated in the SCK/Mol BR2 reactor. The main outputs given by MAIA throughout the irradiation are temperatures, cladding oxidation thickness, interaction thickness, volume fraction of meat constituents, swelling, displacements, strains and stresses. MAIA is originally a two-dimensional code but a three-dimensional version is currently under development. (author)« less

Far-field analysis of coupled bulk and boundary layer diffusion toward an ion channel entrance.

PubMed Central

Schumaker, M F; Kentler, C J

1998-01-01

We present a far-field analysis of ion diffusion toward a channel embedded in a membrane with a fixed charge density. The Smoluchowski equation, which represents the 3D problem, is approximated by a system of coupled three- and two-dimensional diffusions. The 2D diffusion models the quasi-two-dimensional diffusion of ions in a boundary layer in which the electrical potential interaction with the membrane surface charge is important. The 3D diffusion models ion transport in the bulk region outside the boundary layer. Analytical expressions for concentration and flux are developed that are accurate far from the channel entrance. These provide boundary conditions for a numerical solution of the problem. Our results are used to calculate far-field ion flows corresponding to experiments of Bell and Miller (Biophys. J. 45:279, 1984). PMID:9591651

Oblique Collision of the Leeward Antilles, Offshore Venezuela: Linking Onshore and Offshore Data from BOLIVAR

NASA Astrophysics Data System (ADS)

Beardsley, A. G.; Avé Lallemant, H. G.; Levander, A.; Clark, S. A.

2006-12-01

The kinematic history of the Leeward Antilles (offshore Venezuela) can be characterized with the integration of onshore outcrop data and offshore seismic reflection data. Deformation structures and seismic interpretation show that oblique convergence and wrench tectonics have controlled the diachronous deformation identified along the Caribbean - South America plate boundary. Field studies of structural features in outcrop indicate one generation of ductile deformation (D1) structures and three generations of brittle deformation (F1 - F3) structures. The earliest deformation (D1/F1) began ~ 110 Ma with oblique convergence between the Caribbean plate and South American plate. The second generation of deformation (F2) structures initiated in the Eocene with the extensive development of strike-slip fault systems along the diffuse plate boundary and the onset of wrench tectonics within a large-scale releasing bend. The most recent deformation (F3) has been observed in the west since the Miocene where continued dextral strike-slip motion has led to the development of a major restraining bend between the Caribbean plate transform fault and the Oca - San Sebastian - El Pilar fault system. Deformation since the late Cretaceous has been accompanied by a total of 135° clockwise rotation. Interpretation of 2D marine reflection data indicates similar onshore and offshore deformation trends. Seismic lines that approximately parallel the coastline (NW-SE striking) show syndepositional normal faulting during F1/F2 and thrust faulting associated with F3. On seismic lines striking NNE-SSW, we interpret inversion of F2 normal faults with recent F3 deformation. We also observe both normal and thrust faults related to F3. The thick sequence of recent basin sedimentation (Miocene - Recent), interpreted from the seismic data, supports the ongoing uplift and erosion of the islands; as suggested by fluid inclusion analysis. Overall, there appears to be a strong correlation between onshore micro- and mesoscopic deformational structures and offshore macro-scale structural features seen in the reflection data. The agreement of features supports our regional deformation and rotation model along the Caribbean - South America obliquely convergent plate boundary.