Projection-based stabilization of interface Lagrange multipliers in immersogeometric fluid-thin structure interaction analysis, with application to heart valve modeling.

PubMed

Kamensky, David; Evans, John A; Hsu, Ming-Chen; Bazilevs, Yuri

2017-11-01

This paper discusses a method of stabilizing Lagrange multiplier fields used to couple thin immersed shell structures and surrounding fluids. The method retains essential conservation properties by stabilizing only the portion of the constraint orthogonal to a coarse multiplier space. This stabilization can easily be applied within iterative methods or semi-implicit time integrators that avoid directly solving a saddle point problem for the Lagrange multiplier field. Heart valve simulations demonstrate applicability of the proposed method to 3D unsteady simulations. An appendix sketches the relation between the proposed method and a high-order-accurate approach for simpler model problems.

Development and Evaluation of a Hydrostatic Dynamical Core Using the Spectral Element/Discontinuous Galerkin Methods

DTIC Science & Technology

2014-04-01

The CG and DG horizontal discretization employs high-order nodal basis functions associated with Lagrange polynomials based on Gauss-Lobatto- Legendre ...and DG horizontal discretization employs high-order nodal basis functions 29 associated with Lagrange polynomials based on Gauss-Lobatto- Legendre ...Inside 235 each element we build ( 1)N + Gauss-Lobatto- Legendre (GLL) quadrature points, where N 236 indicate the polynomial order of the basis

A discontinuous Galerkin method for the shallow water equations in spherical triangular coordinates

NASA Astrophysics Data System (ADS)

Läuter, Matthias; Giraldo, Francis X.; Handorf, Dörthe; Dethloff, Klaus

2008-12-01

A global model of the atmosphere is presented governed by the shallow water equations and discretized by a Runge-Kutta discontinuous Galerkin method on an unstructured triangular grid. The shallow water equations on the sphere, a two-dimensional surface in R3, are locally represented in terms of spherical triangular coordinates, the appropriate local coordinate mappings on triangles. On every triangular grid element, this leads to a two-dimensional representation of tangential momentum and therefore only two discrete momentum equations. The discontinuous Galerkin method consists of an integral formulation which requires both area (elements) and line (element faces) integrals. Here, we use a Rusanov numerical flux to resolve the discontinuous fluxes at the element faces. A strong stability-preserving third-order Runge-Kutta method is applied for the time discretization. The polynomial space of order k on each curved triangle of the grid is characterized by a Lagrange basis and requires high-order quadature rules for the integration over elements and element faces. For the presented method no mass matrix inversion is necessary, except in a preprocessing step. The validation of the atmospheric model has been done considering standard tests from Williamson et al. [D.L. Williamson, J.B. Drake, J.J. Hack, R. Jakob, P.N. Swarztrauber, A standard test set for numerical approximations to the shallow water equations in spherical geometry, J. Comput. Phys. 102 (1992) 211-224], unsteady analytical solutions of the nonlinear shallow water equations and a barotropic instability caused by an initial perturbation of a jet stream. A convergence rate of O(Δx) was observed in the model experiments. Furthermore, a numerical experiment is presented, for which the third-order time-integration method limits the model error. Thus, the time step Δt is restricted by both the CFL-condition and accuracy demands. Conservation of mass was shown up to machine precision and energy conservation converges for both increasing grid resolution and increasing polynomial order k.

Software for C1 interpolation

NASA Technical Reports Server (NTRS)

Lawson, C. L.

1977-01-01

The problem of mathematically defining a smooth surface, passing through a finite set of given points is studied. Literature relating to the problem is briefly reviewed. An algorithm is described that first constructs a triangular grid in the (x,y) domain, and first partial derivatives at the modal points are estimated. Interpolation in the triangular cells using a method that gives C sup.1 continuity overall is examined. Performance of software implementing the algorithm is discussed. Theoretical results are presented that provide valuable guidance in the development of algorithms for constructing triangular grids.

Deployment and Simulation of the Astrod-Gw Formation

NASA Astrophysics Data System (ADS)

Wu, An-Ming; Ni, Wei-Tou

2013-01-01

Constellation or formation flying is a common concept in space Gravitational Wave (GW) mission proposals for the required interferometry implementation. The spacecraft of most of these mission proposals go to deep space and many have Earthlike orbits around the Sun. Astrodynamical Space Test of Relativity using Optical Devices optimized for Gravitation Wave detection (ASTROD-GW), Big Bang Observer (BBO) and DECIGO have spacecraft distributed in Earthlike orbits in formation. The deployment of orbit formation is an important issue for these missions. ASTROD-GW is to focus on the goal of detection of GWs. The mission orbits of the three spacecraft forming a nearly equilateral triangular array are chosen to be near the Sun-Earth Lagrange points L3, L4 and L5. The three spacecraft range interferometrically with one another with arm length about 260 million kilometers with the scientific goals including detection of GWs from Massive Black Holes (MBH) and Extreme-Mass-Ratio Black Hole Inspirals (EMRI), and using these observations to find the evolution of the equation of state of dark energy and to explore the co-evolution of MBH with galaxies. In this paper, we review the formation flying for fundamental physics missions, design the preliminary transfer orbits of the ASTROD-GW spacecraft from the separations of the launch vehicles to the mission orbits, and simulate the arm lengths of the triangular formation. From our study, the optimal delta-Vs and propellant ratios of the transfer orbits could be within about 2.5 km/s and 0.55, respectively. From the simulation of the formation for 10 years, the arm lengths of the formation vary in the range 1.73210 ± 0.00015 AU with the arm length differences varying in the range ±0.00025 AU for formation with 1° inclination to the ecliptic plane. This meets the measurement requirements. Further studies on the optimizations of deployment and orbit configurations for a period of 20 years and with inclinations between 1° to 3° are currently ongoing.

Significance of specific force models in two applications: Solar sails to sun-earth L4/L5 and grail data analysis suggesting lava tubes and buried craters on the moon

NASA Astrophysics Data System (ADS)

Sood, Rohan

In the trajectory design process, gravitational interaction between the bodies of interest plays a key role in developing the over-arching force model. However, non-gravitational forces, such as solar radiation pressure (SRP), can significantly influence the motion of a spacecraft. Incorporating SRP within the dynamical model can assist in estimating the trajectory of a spacecraft with greater precision, in particular, for a spacecraft with a large area-to-mass ratio, i.e., solar sails. Subsequently, in the trajectory design process, solar radiation pressure can be leveraged to maneuver the sail-based spacecraft. First, to construct low energy transfers, the invariant manifolds are explored that form an important tool in the computation and design of complex trajectories. The focus is the investigation of trajectory design options, incorporating solar sail dynamics, from the Earth parking orbit to the vicinity of triangular Lagrange points. Thereafter, an optimization scheme assisted in investigating the ?V requirement to depart from the Earth parking orbit. Harnessing the solar radiation pressure, the spacecraft is delivered to the vicinity of the displaced Lagrange point and maintains a trajectory close to the artificial libration point with the help of the solar sail. However, these trajectories are converged in a model formulated as a three-body problem with additional acceleration from solar radiation pressure. Thus, the trajectories are transitioned to higher fidelity ephemeris model to account for additional perturbing accelerations that may dominate the sail-craft dynamics and improve upon the trajectory design process. Alternatively, precise knowledge of the motion of a spacecraft about a central body and the contribution of the SRP can assist in deriving a highly accurate gravity field model. The high resolution gravity data can potentially assist in exploring the surface and subsurface properties of a particular body. With the goal of expanding human presence beyond Earth, sub-surface empty lava tubes on other worlds form ideal candidates for creating a permanent habitation environment safe from cosmic radiation, micrometeorite impacts and temperature extremes. In addition, gravitational analysis has also revealed large buried craters under thick piles of mare basalt, shedding light on Moon's dynamic and hostile past. In this work, gravity mapping observations from NASA's Gravity Recovery and Interior Laboratory (GRAIL) are employed to detect the presence of potential empty lava tubes and large impact craters buried beneath the lunar maria.

Efficient generation of discontinuity-preserving adaptive triangulations from range images.

PubMed

Garcia, Miguel Angel; Sappa, Angel Domingo

2004-10-01

This paper presents an efficient technique for generating adaptive triangular meshes from range images. The algorithm consists of two stages. First, a user-defined number of points is adaptively sampled from the given range image. Those points are chosen by taking into account the surface shapes represented in the range image in such a way that points tend to group in areas of high curvature and to disperse in low-variation regions. This selection process is done through a noniterative, inherently parallel algorithm in order to gain efficiency. Once the image has been subsampled, the second stage applies a two and one half-dimensional Delaunay triangulation to obtain an initial triangular mesh. To favor the preservation of surface and orientation discontinuities (jump and crease edges) present in the original range image, the aforementioned triangular mesh is iteratively modified by applying an efficient edge flipping technique. Results with real range images show accurate triangular approximations of the given range images with low processing times.

Diffraction of V-point singularities through triangular apertures.

PubMed

Ram, B S Bhargava; Sharma, Anurag; Senthilkumaran, P

2017-05-01

In this paper we present experimental studies on diffraction of V-point singularities through equilateral and isosceles right triangular apertures. When V-point index, also called Poincare-Hopf index (η), of the optical field is +1, the diffraction disintegrates it into two monstars/lemons. When V-point index η is -1, diffraction produces two stars. The diffraction pattern, unlike phase singularity, is insensitive to polarity of the polarization singularity and the intensity pattern remains invariant. Higher order V-point singularities are generated using Sagnac interferometer and it is observed that the diffraction disintegrates them into lower order C-points.

Free-Lagrange methods for compressible hydrodynamics in two space dimensions

NASA Astrophysics Data System (ADS)

Crowley, W. E.

1985-03-01

Since 1970 a research and development program in Free-Lagrange methods has been active at Livermore. The initial steps were taken with incompressible flows for simplicity. Since then the effort has been concentrated on compressible flows with shocks in two space dimensions and time. In general, the line integral method has been used to evaluate derivatives and the artificial viscosity method has been used to deal with shocks. Basically, two Free-Lagrange formulations for compressible flows in two space dimensions and time have been tested and both will be described. In method one, all prognostic quantities were node centered and staggered in time. The artificial viscosity was zone centered. One mesh reconnection philosphy was that the mesh should be optimized so that nearest neighbors were connected together. Another was that vertex angles should tend toward equality. In method one, all mesh elements were triangles. In method two, both quadrilateral and triangular mesh elements are permitted. The mesh variables are staggered in space and time as suggested originally by Richtmyer and von Neumann. The mesh reconnection strategy is entirely different in method two. In contrast to the global strategy of nearest neighbors, we now have a more local strategy that reconnects in order to keep the integration time step above a user chosen threshold. An additional strategy reconnects in the vicinity of large relative fluid motions. Mesh reconnection consists of two parts: (1) the tools that permits nodes to be merged and quads to be split into triangles etc. and; (2) the strategy that dictates how and when to use the tools. Both tools and strategies change with time in a continuing effort to expand the capabilities of the method. New ideas are continually being tried and evaluated.

50 CFR Figures 18a, 18b and 18c to... - Large Frame TED Escape Opening; Minimum Dimensions Using All-Bar Cuts (Triangular Cuts); Large...

Code of Federal Regulations, 2013 CFR

2013-10-01

... Dimensions Using All-Bar Cuts (Triangular Cuts); Large Frame TED Escape Opening; Minimum Dimensions Using All-Bar Cuts and Leading Edge Cut; Large Frame TED Escape Opening; Minimum Dimensions Using All-Points...—Large Frame TED Escape Opening; Minimum Dimensions Using All-Bar Cuts (Triangular Cuts); Large Frame TED...

50 CFR Figures 18a, 18b and 18c to... - Large Frame TED Escape Opening; Minimum Dimensions Using All-Bar Cuts (Triangular Cuts); Large...

Code of Federal Regulations, 2012 CFR

2012-10-01

... Dimensions Using All-Bar Cuts (Triangular Cuts); Large Frame TED Escape Opening; Minimum Dimensions Using All-Bar Cuts and Leading Edge Cut; Large Frame TED Escape Opening; Minimum Dimensions Using All-Points...—Large Frame TED Escape Opening; Minimum Dimensions Using All-Bar Cuts (Triangular Cuts); Large Frame TED...

50 CFR Figures 18a, 18b and 18c to... - Large Frame TED Escape Opening; Minimum Dimensions Using All-Bar Cuts (Triangular Cuts); Large...

Code of Federal Regulations, 2014 CFR

2014-10-01

... Dimensions Using All-Bar Cuts (Triangular Cuts); Large Frame TED Escape Opening; Minimum Dimensions Using All-Bar Cuts and Leading Edge Cut; Large Frame TED Escape Opening; Minimum Dimensions Using All-Points...—Large Frame TED Escape Opening; Minimum Dimensions Using All-Bar Cuts (Triangular Cuts); Large Frame TED...

Coupling effect of topological states and Chern insulators in two-dimensional triangular lattices

NASA Astrophysics Data System (ADS)

Zhang, Jiayong; Zhao, Bao; Xue, Yang; Zhou, Tong; Yang, Zhongqin

2018-03-01

We investigate topological states of two-dimensional (2D) triangular lattices with multiorbitals. Tight-binding model calculations of a 2D triangular lattice based on px and py orbitals exhibit very interesting doubly degenerate energy points at different positions (Γ and K /K' ) in momentum space, with quadratic non-Dirac and linear Dirac band dispersions, respectively. Counterintuitively, the system shows a global topologically trivial rather than nontrivial state with consideration of spin-orbit coupling due to the "destructive interference effect" between the topological states at the Γ and K /K' points. The topologically nontrivial state can emerge by introducing another set of triangular lattices to the system (bitriangular lattices) due to the breakdown of the interference effect. With first-principles calculations, we predict an intrinsic Chern insulating behavior (quantum anomalous Hall effect) in a family of the 2D triangular lattice metal-organic framework of Co(C21N3H15) (TPyB-Co) from this scheme. Our results provide a different path and theoretical guidance for the search for and design of new 2D topological quantum materials.

Stability of triangular lagrangian points in elliptical restricted three body problem under the radiating binary systems

NASA Astrophysics Data System (ADS)

Narayan, A.; Singh, Nutan

2014-10-01

This paper studies the stability of Triangular Lagrangian points in the model of elliptical restricted three body problem, under the assumption that both the primaries are radiating. The model proposed is applicable to the well known binary systems Achird, Luyten, αCen AB, Kruger-60, Xi-Bootis. Conditional stability of the motion around the triangular points exists for 0≤ μ≤ μ ∗, where μ is the mass ratio. The method of averaging due to Grebenikov has been exploited throughout the analysis of stability of the system. The critical mass ratio depends on the combined effects of radiation of both the primaries and eccentricity of this orbit. It is found by adopting the simulation technique that the range of stability decreases as the radiation pressure parameter increases.

Synthesis of a controller for stabilizing the motion of a rigid body about a fixed point

NASA Astrophysics Data System (ADS)

Zabolotnov, Yu. M.; Lobanov, A. A.

2017-05-01

A method for the approximate design of an optimal controller for stabilizing the motion of a rigid body about a fixed point is considered. It is assumed that rigid body motion is nearly the motion in the classical Lagrange case. The method is based on the common use of the Bellman dynamic programming principle and the averagingmethod. The latter is used to solve theHamilton-Jacobi-Bellman equation approximately, which permits synthesizing the controller. The proposed method for controller design can be used in many problems close to the problem of motion of the Lagrange top (the motion of a rigid body in the atmosphere, the motion of a rigid body fastened to a cable in deployment of the orbital cable system, etc.).

A suggested trajectory for a Venus-sun, earth-sun Lagrange points mission, Vela

NASA Technical Reports Server (NTRS)

Bender, D. F.

1979-01-01

The possibility is suggested of investigating the existence of small, as-yet undiscovered, asteroids orbiting in the solar system near the earth-sun or Venus-sun stable Lagrange points by means of a spacecraft which traverses these regions. The type of trajectory suggested lies in the ecliptic plane and has a period of 5/6 years and a perihelion at the Venus orbital distance. The regions in which stable orbits associated with the earth and with Venus may lie are estimated to be a thin and tadpole-shaped area extending from 35 deg to 100 deg from the planet. Crossings of the regions by the trajectory are described, and the requirements for detecting the presence of 1 km sized asteroids are presented and shown to be attainable.

Triangular Libration Points in the CR3BP with Radiation, Triaxiality and Potential from a Belt

NASA Astrophysics Data System (ADS)

Singh, Jagadish; Taura, Joel John

2017-07-01

In this paper the equations of motion of the circular restricted three body problem is modified to include radiation of the bigger primary, triaxiality of the smaller primary; and gravitational potential created by a belt. We have obtained that due to the perturbations, the locations of the triangular libration points and their linear stability are affected. The points move towards the bigger primary due to the resultant effect of the perturbations. Triangular libration points are stable for 0<μ<μc0<μ<μc and unstable for μc≤μ≤12μc≤μ≤12, where μcμc is the critical mass ratio affected by the perturbations. The radiation of the bigger primary and triaxiality of the smaller primary have destabilizing propensities, whereas the potential created by the belt has stabilizing propensity. This model could be applied in the study of the motion of a dust particle near radiating -triaxial binary system surrounded by a belt.

Heteroclinic, Homoclinic Connections Between the Sun-Earth Triangular Points and Quasi-Satellite Orbits for Solar Observations

NASA Technical Reports Server (NTRS)

Llanos, Pedro J.; Hintz, Gerald R.; Lo, Martin W.; Miller, James K.

2013-01-01

Investigation of new orbit geometries exhibits a very attractive behavior for a spacecraft to monitor space weather coming from the Sun. Several orbit transfer mechanisms are analyzed as potential alternatives to monitor solar activity such as a sub-solar orbit or quasi-satellite orbit and short and long heteroclinic and homoclinic connections between the triangular points L(sub 4) and L(sub 5) and the collinear point L(sub 3) of the Circular Restricted Three-Body Problem (CRTBP) in the Sun-Earth system.

Convex Hull Aided Registration Method (CHARM).

PubMed

Fan, Jingfan; Yang, Jian; Zhao, Yitian; Ai, Danni; Liu, Yonghuai; Wang, Ge; Wang, Yongtian

2017-09-01

Non-rigid registration finds many applications such as photogrammetry, motion tracking, model retrieval, and object recognition. In this paper we propose a novel convex hull aided registration method (CHARM) to match two point sets subject to a non-rigid transformation. First, two convex hulls are extracted from the source and target respectively. Then, all points of the point sets are projected onto the reference plane through each triangular facet of the hulls. From these projections, invariant features are extracted and matched optimally. The matched feature point pairs are mapped back onto the triangular facets of the convex hulls to remove outliers that are outside any relevant triangular facet. The rigid transformation from the source to the target is robustly estimated by the random sample consensus (RANSAC) scheme through minimizing the distance between the matched feature point pairs. Finally, these feature points are utilized as the control points to achieve non-rigid deformation in the form of thin-plate spline of the entire source point set towards the target one. The experimental results based on both synthetic and real data show that the proposed algorithm outperforms several state-of-the-art ones with respect to sampling, rotational angle, and data noise. In addition, the proposed CHARM algorithm also shows higher computational efficiency compared to these methods.

Error estimates of Lagrange interpolation and orthonormal expansions for Freud weights

NASA Astrophysics Data System (ADS)

Kwon, K. H.; Lee, D. W.

2001-08-01

Let Sn[f] be the nth partial sum of the orthonormal polynomials expansion with respect to a Freud weight. Then we obtain sufficient conditions for the boundedness of Sn[f] and discuss the speed of the convergence of Sn[f] in weighted Lp space. We also find sufficient conditions for the boundedness of the Lagrange interpolation polynomial Ln[f], whose nodal points are the zeros of orthonormal polynomials with respect to a Freud weight. In particular, if W(x)=e-(1/2)x2 is the Hermite weight function, then we obtain sufficient conditions for the inequalities to hold:andwhere and k=0,1,2...,r.

Science Enabled by the Ares V: A Large Monolithic Telescope Placed at the Second Sun-Earth Lagrange Point

NASA Technical Reports Server (NTRS)

Hopkins, Randall C.; Stahl, H. Philip

2007-01-01

The payload mass and volume capabilities of the planned Ares V launch vehicle provide the science community with unprecedented opportunities to place large science payloads into low earth orbit and beyond. One example, the outcome of a recent study conducted at the NASA Marshall Space Flight Center, is a large, monolithic telescope with a primary mirror diameter of 6.2 meters placed into a halo orbit about the second Sun-Earth Lagrange point, or L2, approximately 1.5 million kin beyond Earth's orbit. Operating in the visible and ultraviolet regions of the electromagnetic spectrum, such a large telescope would allow astronomers to detect bio-signatures and characterize the atmospheres of transiting exoplanets, provide high resolution imaging three or more times better than the Hubble Space Telescope and the James Webb Space Telescope, and observe the ultraviolet light from warm baryonic matter.

Smoot Cosmology Group

Science.gov Websites

orbit around L2, the second Lagrange point of the Earth-Sun system, which is about 1.5 million orbits L2, it makes one rotation about the Sun per year. The spacecraft spin axis has to be rotated at the same rate in order to remain Sun pointed. This is achieved by making regular manoeuvres that will

DSCOVR: A New Perspective for Earth Observations from Space. Synergism and Complementarity with Existing Platforms

NASA Astrophysics Data System (ADS)

Valero, F. P.

2011-12-01

The Sun-Earth Lagrange points L-1 and L-2 mark positions where the gravitational pull of the Earth and Sun precisely equals the centripetal force required to rotate with the Earth about the Sun with the same orbital period as the Earth. Therefore, a satellite maintained at one of these Lagrange points would keep the same relative position to the Sun and the Earth and be able to observe most points on the planet as the Earth rotates during the day. L-1 and L-2 are of particular interest because a satellite at either location can easily be maintained near the Sun-Earth line and views the entire daytime hemisphere from L-1 and the entire nighttime hemisphere from L-2. Since L-1 and L-2 are in the ecliptic plane, synoptic, high temporal-resolution observations would be obtained as every point on the planet, including both polar regions, transits from sunrise to sunset (L-1) or from sunset to sunrise (L-2). In summary, a pair of deep-space observatories, one at L-1 (daytime) and one at L-2 (nighttime), could acquire minute by minute climate quality data for essentially every point on Earth, all observations simultaneously for the whole planet. Such unique attributes are incorporated in the Deep Space Climate Observatory (DSCOVR) that will systematically observe climate drivers (radiation, aerosols, ozone, clouds, oxygen A-band) from L-1 in ways not possible but synergistically complementary with platforms in Low Earth Orbit (LEO) or Geostationary Earth Orbit (GEO). The combination of Solar Lagrange Points (located in the ecliptic plane) GEO (located in the equatorial plane) and LEO platforms would certainly provide a powerful observational tool as well as enriched data sets for Earth sciences. Such synergism is greatly enhanced when one considers the potential of utilizing LEO, GEO, and Lagrange point satellites as components of an integrated observational system. For example, satellites at L-1 and L-2 will view the Earth plus the Moon while simultaneously having in their fields of view (at one time or another) all Earth-orbiting and GEO satellites. This view offers the opportunity to use the Moon as a comparison reference that can in turn be shared with all other Earth observation satellites. The L-1 and L-2 observatories can become important links between LEO and GEO satellites while at the same time providing the data necessary to build an integrated Earth observational system. A synergistic, integrated system composed of LEO, GEO, L-1 and L-2 platforms is likely the way of the future.

Wave Propagation Analysis of Edge Cracked Circular Beams under Impact Force

PubMed Central

Akbaş, Şeref Doğuşcan

2014-01-01

This paper presents responses of an edge circular cantilever beam under the effect of an impact force. The beam is excited by a transverse triangular force impulse modulated by a harmonic motion. The Kelvin–Voigt model for the material of the beam is used. The cracked beam is modelled as an assembly of two sub-beams connected through a massless elastic rotational spring. The considered problem is investigated within the Bernoulli-Euler beam theory by using energy based finite element method. The system of equations of motion is derived by using Lagrange's equations. The obtained system of linear differential equations is reduced to a linear algebraic equation system and solved in the time domain by using Newmark average acceleration method. In the study, the effects of the location of crack, the depth of the crack, on the characteristics of the reflected waves are investigated in detail. Also, the positions of the cracks are calculated by using reflected waves. PMID:24972050

SPHERES tethered formation flight testbed: application to NASA's SPECS mission

NASA Astrophysics Data System (ADS)

Chung, Soon-Jo; Kong, Edmund M.; Miller, David W.

2005-08-01

This paper elaborates on theory and experiment of the formation flight control for the future space-borne tethered interferometers. The nonlinear equations of multi-vehicle tethered spacecraft system are derived by Lagrange equations and decoupling method. The preliminary analysis predicts unstable dynamics depending on the direction of the tether motor. The controllability analysis indicates that both array resizing and spin-up are fully controllable only by the reaction wheels and the tether motor, thereby eliminating the need for thrusters. Linear and nonlinear decentralized control techniques have been implemented into the tethered SPHERES testbed, and tested at the NASA MSFC's flat floor facility using two and three SPHERES configurations. The nonlinear control using feedback linearization technique performed successfully in both two SPHERES in-line configuration and three triangular configuration while varying the tether length. The relative metrology system, using the ultra sound metrology system and the inertial sensors as well as the decentralized nonlinear estimator, is developed to provide necessary state information.

Higher Order Lagrange Finite Elements In M3D

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

J. Chen; H.R. Strauss; S.C. Jardin

The M3D code has been using linear finite elements to represent multilevel MHD on 2-D poloidal planes. Triangular higher order elements, up to third order, are constructed here in order to provide M3D the capability to solve highly anisotropic transport problems. It is found that higher order elements are essential to resolve the thin transition layer characteristic of the anisotropic transport equation, particularly when the strong anisotropic direction is not aligned with one of the Cartesian coordinates. The transition layer is measured by the profile width, which is zero for infinite anisotropy. It is shown that only higher order schemesmore » have the ability to make this layer converge towards zero when the anisotropy gets stronger and stronger. Two cases are considered. One has the strong transport direction partially aligned with one of the element edges, the other doesn't have any alignment. Both cases have the strong transport direction misaligned with the grid line by some angles.« less

16QAM Blind Equalization via Maximum Entropy Density Approximation Technique and Nonlinear Lagrange Multipliers

PubMed Central

Mauda, R.; Pinchas, M.

2014-01-01

Recently a new blind equalization method was proposed for the 16QAM constellation input inspired by the maximum entropy density approximation technique with improved equalization performance compared to the maximum entropy approach, Godard's algorithm, and others. In addition, an approximated expression for the minimum mean square error (MSE) was obtained. The idea was to find those Lagrange multipliers that bring the approximated MSE to minimum. Since the derivation of the obtained MSE with respect to the Lagrange multipliers leads to a nonlinear equation for the Lagrange multipliers, the part in the MSE expression that caused the nonlinearity in the equation for the Lagrange multipliers was ignored. Thus, the obtained Lagrange multipliers were not those Lagrange multipliers that bring the approximated MSE to minimum. In this paper, we derive a new set of Lagrange multipliers based on the nonlinear expression for the Lagrange multipliers obtained from minimizing the approximated MSE with respect to the Lagrange multipliers. Simulation results indicate that for the high signal to noise ratio (SNR) case, a faster convergence rate is obtained for a channel causing a high initial intersymbol interference (ISI) while the same equalization performance is obtained for an easy channel (initial ISI low). PMID:24723813

End of Life Disposal for Three Libration Point Missions through Manipulation of the Jacobi Constant and Zero Velocity Curves

NASA Technical Reports Server (NTRS)

Petersen, Jeremy; Brown, Jonathan

2015-01-01

Flight Dynamics Facility (FDF) located at NASA Goddard Space Flight Center (GSFC) provides the flight dynamics expertise for three Sun-Earth Moon L1 missions. Advanced Composition Explorer (ACE) launched August 1997 Solar and Heliospheric Observatory (SOHO) launched December 1995 Global Geospace Science WIND satellite launched November 1994 entered Lagrange point orbit in 2004.

Modified Interior Distance Functions (Theory and Methods)

NASA Technical Reports Server (NTRS)

Polyak, Roman A.

1995-01-01

In this paper we introduced and developed the theory of Modified Interior Distance Functions (MIDF's). The MIDF is a Classical Lagrangian (CL) for a constrained optimization problem which is equivalent to the initial one and can be obtained from the latter by monotone transformation both the objective function and constraints. In contrast to the Interior Distance Functions (IDF's), which played a fundamental role in Interior Point Methods (IPM's), the MIDF's are defined on an extended feasible set and along with center, have two extra tools, which control the computational process: the barrier parameter and the vector of Lagrange multipliers. The extra tools allow to attach to the MEDF's very important properties of Augmented Lagrangeans. One can consider the MIDFs as Interior Augmented Lagrangeans. It makes MIDF's similar in spirit to Modified Barrier Functions (MBF's), although there is a fundamental difference between them both in theory and methods. Based on MIDF's theory, Modified Center Methods (MCM's) have been developed and analyzed. The MCM's find an unconstrained minimizer in primal space and update the Lagrange multipliers, while both the center and the barrier parameter can be fixed or updated at each step. The MCM's convergence was investigated, and their rate of convergence was estimated. The extension of the feasible set and the special role of the Lagrange multipliers allow to develop MCM's, which produce, in case of nondegenerate constrained optimization, a primal and dual sequences that converge to the primal-dual solutions with linear rate, even when both the center and the barrier parameter are fixed. Moreover, every Lagrange multipliers update shrinks the distance to the primal dual solution by a factor 0 less than gamma less than 1 which can be made as small as one wants by choosing a fixed interior point as a 'center' and a fixed but large enough barrier parameter. The numericai realization of MCM leads to the Newton MCM (NMCM). The approximation for the primal minimizer one finds by Newton Method followed by the Lagrange multipliers update. Due to the MCM convergence, when both the center and the barrier parameter are fixed, the condition of the MDF Hessism and the neighborhood of the primal ninimizer where Newton method is 'well' defined remains stable. It contributes to both the complexity and the numerical stability of the NMCM.

Optimization of constrained density functional theory

NASA Astrophysics Data System (ADS)

O'Regan, David D.; Teobaldi, Gilberto

2016-07-01

Constrained density functional theory (cDFT) is a versatile electronic structure method that enables ground-state calculations to be performed subject to physical constraints. It thereby broadens their applicability and utility. Automated Lagrange multiplier optimization is necessary for multiple constraints to be applied efficiently in cDFT, for it to be used in tandem with geometry optimization, or with molecular dynamics. In order to facilitate this, we comprehensively develop the connection between cDFT energy derivatives and response functions, providing a rigorous assessment of the uniqueness and character of cDFT stationary points while accounting for electronic interactions and screening. In particular, we provide a nonperturbative proof that stable stationary points of linear density constraints occur only at energy maxima with respect to their Lagrange multipliers. We show that multiple solutions, hysteresis, and energy discontinuities may occur in cDFT. Expressions are derived, in terms of convenient by-products of cDFT optimization, for quantities such as the dielectric function and a condition number quantifying ill definition in multiple constraint cDFT.

Effectiveness of Rotation-free Triangular and Quadrilateral Shell Elements in Sheet-metal Forming Simulations

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

Brunet, M.; Sabourin, F.

2005-08-05

This paper is concerned with the effectiveness of triangular 3-node shell element without rotational d.o.f. and the extension to a new 4-node quadrilateral shell element called S4 with only 3 translational degrees of freedom per node and one-point integration. The curvatures are computed resorting to the surrounding elements. Extension from rotation-free triangular element to a quadrilateral element requires internal curvatures in order to avoid singular bending stiffness. Two numerical examples with regular and irregular meshes are performed to show the convergence and accuracy. Deep-drawing of a box, spring-back analysis of a U-shape strip sheet and the crash simulation of amore » beam-box complete the demonstration of the bending capabilities of the proposed rotation-free triangular and quadrilateral elements.« less

Polestitters: Using Solar Sails for Constant Real-time Sensing of Earth's Polar Regions

NASA Astrophysics Data System (ADS)

Mulligan, P.; Diedrich, B. L.; Barnes, N.; Derbes, B.

2012-12-01

NASA has funded the Sunjammer mission - a near term demonstration of solar sail technology (2014/15). Sunjammer has the potential to demonstrate stationkeeping out of Earth's orbital plane. This is a first step in achieving "polesitter" orbits with year-round, real-time visibility of Earth's polar regions. Potential applications for such missions are illustrated. Solar sails have long been a concept for spacecraft propulsion that works by exchanging momentum with sunlight reflected by large, lightweight, mirrored sails. In addition to enabling propellantless propulsion throughout the solar system and beyond, their continuous thrust enables artificial Lagrange orbits (ALOs), some of which can be called "polesitter" orbits, with 24-hour, year-round visibility of Earth's polar regions. Several potential Earth remote sensing applications have been identified that address the limited temporal and spatial coverage from traditional polar and geostationary satellites. The Galileo spacecraft during its 1990 Earth flyby acquired imagery and radiometer data similar to the view from a polesitter. The Galileo imagery was used to derive aerosols and cloud variations used in atmospheric motion vector (AMV) derivations. Composites of satellite imagery over the South Pole is routinely used to derive atmospheric motion vectors like those performed regularly from geostationary satellites. The JAXA IKAROS mission flew a 14x14m solar sail past Venus in 2010. Sunjammer will demonstrate a state of the art 38x38m solar sail from Earth to an artificial Lagrange orbit located sunward and north of the sun-Earth L1 point. Traditional spacecraft can orbit naturally occurring Lagrange equilibrium points between the sun and Earth. The low, continuous thrust of solar sails can change where these points occur, creating new orbits with a variety of potential applications including polar remote sensing, space weather monitoring, and polar communications. This figure illustrates a selection of possible solar sail orbits around the sun-Earth L1 and L2 points.

Characterization of high order spatial discretizations and lumping techniques for discontinuous finite element SN transport

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

Maginot, P. G.; Ragusa, J. C.; Morel, J. E.

2013-07-01

We examine several possible methods of mass matrix lumping for discontinuous finite element discrete ordinates transport using a Lagrange interpolatory polynomial trial space. Though positive outflow angular flux is guaranteed with traditional mass matrix lumping in a purely absorbing 1-D slab cell for the linear discontinuous approximation, we show that when used with higher degree interpolatory polynomial trial spaces, traditional lumping does yield strictly positive outflows and does not increase in accuracy with an increase in trial space polynomial degree. As an alternative, we examine methods which are 'self-lumping'. Self-lumping methods yield diagonal mass matrices by using numerical quadrature restrictedmore » to the Lagrange interpolatory points. Using equally-spaced interpolatory points, self-lumping is achieved through the use of closed Newton-Cotes formulas, resulting in strictly positive outflows in pure absorbers for odd power polynomials in 1-D slab geometry. By changing interpolatory points from the traditional equally-spaced points to the quadrature points of the Gauss-Legendre or Lobatto-Gauss-Legendre quadratures, it is possible to generate solution representations with a diagonal mass matrix and a strictly positive outflow for any degree polynomial solution representation in a pure absorber medium in 1-D slab geometry. Further, there is no inherent limit to local truncation error order of accuracy when using interpolatory points that correspond to the quadrature points of high order accuracy numerical quadrature schemes. (authors)« less

The James Webb Space Telescope

NASA Technical Reports Server (NTRS)

Mather, John

2003-01-01

The James Webb Space Telescope (JWST) will extend the discoveries of the Hubble Space Telescope by deploying a large cooled infrared telescope at the Sun-Earth Lagrange point L2. It will have a 6 m aperture and three instruments covering the wavelength range from 0.6 to 28 microns.

Effect of Finite Particle Size on Convergence of Point Particle Models in Euler-Lagrange Multiphase Dispersed Flow

NASA Astrophysics Data System (ADS)

Nili, Samaun; Park, Chanyoung; Haftka, Raphael T.; Kim, Nam H.; Balachandar, S.

2017-11-01

Point particle methods are extensively used in simulating Euler-Lagrange multiphase dispersed flow. When particles are much smaller than the Eulerian grid the point particle model is on firm theoretical ground. However, this standard approach of evaluating the gas-particle coupling at the particle center fails to converge as the Eulerian grid is reduced below particle size. We present an approach to model the interaction between particles and fluid for finite size particles that permits convergence. We use the generalized Faxen form to compute the force on a particle and compare the results against traditional point particle method. We apportion the different force components on the particle to fluid cells based on the fraction of particle volume or surface in the cell. The application is to a one-dimensional model of shock propagation through a particle-laden field at moderate volume fraction, where the convergence is achieved for a well-formulated force model and back coupling for finite size particles. Comparison with 3D direct fully resolved numerical simulations will be used to check if the approach also improves accuracy compared to the point particle model. Work supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, under Contract No. DE-NA0002378.

Suitable configurations for triangular formation flying about collinear libration points under the circular and elliptic restricted three-body problems

NASA Astrophysics Data System (ADS)

Ferrari, Fabio; Lavagna, Michèle

2018-06-01

The design of formations of spacecraft in a three-body environment represents one of the most promising challenges for future space missions. Two or more cooperating spacecraft can greatly answer some very complex mission goals, not achievable by a single spacecraft. The dynamical properties of a low acceleration environment such as the vicinity of libration points associated to a three-body system, can be effectively exploited to design spacecraft configurations able of satisfying tight relative position and velocity requirements. This work studies the evolution of an uncontrolled formation orbiting in the proximity of periodic orbits about collinear libration points under the Circular and Elliptic Restricted Three-Body Problems. A three spacecraft triangularly-shaped formation is assumed as a representative geometry to be investigated. The study identifies initial configurations that provide good performance in terms of formation keeping, and investigates key parameters that control the relative dynamics between the spacecraft within the three-body system. Formation keeping performance is quantified by monitoring shape and size changes of the triangular formation. The analysis has been performed under five degrees of freedom to define the geometry, the orientation and the location of the triangle in the synodic rotating frame.

Imaging Near-Earth Electron Densities Using Thomson Scattering

DTIC Science & Technology

2009-01-15

geocentric solar magnetospheric (GSM) coordinates1. TECs were initially computed from a viewing loca- tion at the Sun-Earth L1 Lagrange point2 for both...further find that an elliptical Earth orbit (apogee ~30 RE) is a suitable lower- cost option for a demonstration mission. 5. SIMULATED OBSERVATIONS We

Numerical-Diagonalization Study of Magnetization Process of Frustrated Spin-1/2 Heisenberg Antiferromagnets in Two Dimensions: —Triangular- and Kagome-Lattice Antiferromagnets—

NASA Astrophysics Data System (ADS)

Nakano, Hiroki; Sakai, Tôru

2018-06-01

The S = 1/2 triangular- and kagome-lattice Heisenberg antiferromagnets are investigated under a magnetic field using the numerical-diagonalization method. A procedure is proposed to extract data points with very small finite-size deviations using the numerical-diagonalization results for capturing the magnetization curve. For the triangular-lattice antiferromagnet, the plateau edges at one-third the height of the saturation and the saturation field are successfully estimated. This study additionally presents results of magnetization process for a 45-site cluster of the kagome-lattice antiferromagnet; the present analysis suggests that the plateau does not open at one-ninth the height of the saturation.

Improved-resolution real-time skin-dose mapping for interventional fluoroscopic procedures

NASA Astrophysics Data System (ADS)

Rana, Vijay K.; Rudin, Stephen; Bednarek, Daniel R.

2014-03-01

We have developed a dose-tracking system (DTS) that provides a real-time display of the skin-dose distribution on a 3D patient graphic during fluoroscopic procedures. Radiation dose to individual points on the skin is calculated using exposure and geometry parameters from the digital bus on a Toshiba C-arm unit. To accurately define the distribution of dose, it is necessary to use a high-resolution patient graphic consisting of a large number of elements. In the original DTS version, the patient graphics were obtained from a library of population body scans which consisted of larger-sized triangular elements resulting in poor congruence between the graphic points and the x-ray beam boundary. To improve the resolution without impacting real-time performance, the number of calculations must be reduced and so we created software-designed human models and modified the DTS to read the graphic as a list of vertices of the triangular elements such that common vertices of adjacent triangles are listed once. Dose is calculated for each vertex point once instead of the number of times that a given vertex appears in multiple triangles. By reformatting the graphic file, we were able to subdivide the triangular elements by a factor of 64 times with an increase in the file size of only 1.3 times. This allows a much greater number of smaller triangular elements and improves resolution of the patient graphic without compromising the real-time performance of the DTS and also gives a smoother graphic display for better visualization of the dose distribution.

Examination of ductile spall failure through direct numerical simulation

NASA Astrophysics Data System (ADS)

Becker, Richard

2017-06-01

Direct numerical simulation is used to examine the growth and coalescence of a random population of voids leading to spall failure. Void nucleating particles are explicitly represented in the initial geometry, and the arbitrary Lagrange-Eulerian finite element code tracks the void evolution to create the spall surface. The flow fields capture strain localization associated with void interaction at low porosities and ligament necking at final coalescence. Simulations are run to assess the influence of material strain hardening and strain rate sensitivity on void growth and coalescence. These analyses also provide the evolution of longitudinal stress and the energy dissipated, and they reveal a length scale associated with the spall. Additional calculations are performed to examine the influence of loading pulse shape on spall behavior for triangular shaped pressure loading. A dependence of spall scab thickness on pulse shape is determined. These results show localization delayed until porosities reach a few percent and they demonstrate a consistent stress versus porosity relation. The simulations also provide a direct correlation between the spall stress history and the free surface velocity, which can aid in understanding stress corrections applied to experimental data.

Quadratic polynomial interpolation on triangular domain

NASA Astrophysics Data System (ADS)

Li, Ying; Zhang, Congcong; Yu, Qian

2018-04-01

In the simulation of natural terrain, the continuity of sample points are not in consonance with each other always, traditional interpolation methods often can't faithfully reflect the shape information which lie in data points. So, a new method for constructing the polynomial interpolation surface on triangular domain is proposed. Firstly, projected the spatial scattered data points onto a plane and then triangulated them; Secondly, A C1 continuous piecewise quadric polynomial patch was constructed on each vertex, all patches were required to be closed to the line-interpolation one as far as possible. Lastly, the unknown quantities were gotten by minimizing the object functions, and the boundary points were treated specially. The result surfaces preserve as many properties of data points as possible under conditions of satisfying certain accuracy and continuity requirements, not too convex meantime. New method is simple to compute and has a good local property, applicable to shape fitting of mines and exploratory wells and so on. The result of new surface is given in experiments.

The motion near L{sub 4} equilibrium point under non-point mass primaries

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

Huda, I. N., E-mail: ibnu.nurul@students.itb.ac.id; Utama, J. A.; Madley, D.

2015-09-30

The Circular Restricted Three-Body Problem (CRTBP) possesses five equilibrium points, that comprise three collinear (L{sub 1}, L{sub 2}, and L{sub 3}) and two triangular points (L{sub 4} and L{sub 5}). The classical study (with the primaries are point mass) suggests that the equilibrium points may cause the velocity of infinitesimal object relatively becomes zero and reveals the zero velocity curve. We study the motion of infinitesimal object near triangular equilibrium point (L{sub 4}) and determine its zero velocity curve. We extend the study by taking into account the effects of radiation of the bigger primary (q{sub 1} ≠ 1, q{submore » 2} = 1) and oblateness of the smaller primary (A{sub 1} = 0, A{sub 2} ≠ 0). The location of L{sub 4} is analytically derived then the stability of L{sub 4} and its zero velocity curves are studied numerically. Our study suggests that the oblateness and the radiation of primaries may affect the stability and zero velocity curve around L{sub 4}.« less

Optical transmission for the James Webb Space Telescope

NASA Astrophysics Data System (ADS)

Lightsey, Paul A.; Gallagher, Benjamin B.; Nickles, Neal; Copp, Tracy

2012-09-01

The fabrication and coating of the mirrors for the James Webb Space Telescope has been completed. The spectral reflectivity of the protected gold coated beryllium mirrors has been measured. The predicted end-of-life transmission through the telescope builds from these values. The additional phenomena that have been analyzed are contamination effects and effects of the environment for the JWST operation about the Earth-Sun L2 Lagrange libration point. The L2 environment analysis has been based on radiation testing of mirror samples and hypervelocity testing to assess the micrometeoroid impact effects. The mirror showed no change in reflectance over the VIS-SWIR wavelengths after exposure to 6-9 Grad (Si) that simulated 6 years orbiting the L2 Lagrange point. The effects of hypervelocity particle impacts on the mirrors from test data has been extrapolated to the to the anticipated flux characteristics for micrometeoroids at the L2 environment. The results show that the micrometeoroid effects are orders of magnitude below the particulate contamination effects. The final end-of-life transmission for the mirrors including all of these phenomena will meet the performance requirements for JWST.

A brief history of partitions of numbers, partition functions and their modern applications

NASA Astrophysics Data System (ADS)

Debnath, Lokenath

2016-04-01

'Number rules the universe.' The Pythagoras 'If you wish to forsee the future of mathematics our course is to study the history and present conditions of the science.' Henri Poincaré 'The primary source (Urqell) of all mathematics are integers.' Hermann Minkowski This paper is written to commemorate the centennial anniversary of the Mathematical Association of America. It deals with a short history of different kinds of natural numbers including triangular, square, pentagonal, hexagonal and k-gonal numbers, and their simple properties and their geometrical representations. Included are Euclid's and Pythagorean's main contributions to elementary number theory with the main contents of the Euclid Elements of the 13-volume masterpiece of mathematical work. This is followed by Euler's new discovery of the additive number theory based on partitions of numbers. Special attention is given to many examples, Euler's theorems on partitions of numbers with geometrical representations of Ferrers' graphs, Young's diagrams, Lagrange's four-square theorem and the celebrated Waring problem. Included are Euler's generating functions for the partitions of numbers, Euler's pentagonal number theorem, Gauss' triangular and square number theorems and the Jacobi triple product identity. Applications of the theory of partitions of numbers to different statistics such as the Bose- Einstein, Fermi- Dirac, Gentile, and Maxwell- Boltzmann statistics are briefly discussed. Special attention is given to pedagogical information through historical approach to number theory so that students and teachers at the school, college and university levels can become familiar with the basic concepts of partitions of numbers, partition functions and their modern applications, and can pursue advanced study and research in analytical and computational number theory.

Triangular lattice atomic layer of Sn(1 × 1) at graphene/SiC(0001) interface

NASA Astrophysics Data System (ADS)

Hayashi, Shingo; Visikovskiy, Anton; Kajiwara, Takashi; Iimori, Takushi; Shirasawa, Tetsuroh; Nakastuji, Kan; Miyamachi, Toshio; Nakashima, Shuhei; Yaji, Koichiro; Mase, Kazuhiko; Komori, Fumio; Tanaka, Satoru

2018-01-01

Sn atomic layers attract considerable interest owing to their spin-related physical properties caused by their strong spin-orbit interactions. We performed Sn intercalation into the graphene/SiC(0001) interface and found a new type of Sn atomic layer. Sn atoms occupy on-top sites of Si-terminated SiC(0001) with in-plane Sn-Sn bondings, resulting in a triangular lattice. Angle-resolved photoemission spectroscopy revealed characteristic dispersions at \\bar{\\text{K}} and \\bar{\\text{M}} points, which agreed well with density functional theory calculations. The Sn triangular lattice atomic layer at the interface showed no oxidation upon exposure to air, which is useful for characterization and device fabrication ex situ.

Modeling the Global Coronal Field with Simulated Synoptic Magnetograms from Earth and the Lagrange Points L3, L4, and L5

NASA Astrophysics Data System (ADS)

Petrie, Gordon; Pevtsov, Alexei; Schwarz, Andrew; DeRosa, Marc

2018-06-01

The solar photospheric magnetic flux distribution is key to structuring the global solar corona and heliosphere. Regular full-disk photospheric magnetogram data are therefore essential to our ability to model and forecast heliospheric phenomena such as space weather. However, our spatio-temporal coverage of the photospheric field is currently limited by our single vantage point at/near Earth. In particular, the polar fields play a leading role in structuring the large-scale corona and heliosphere, but each pole is unobservable for {>} 6 months per year. Here we model the possible effect of full-disk magnetogram data from the Lagrange points L4 and L5, each extending longitude coverage by 60°. Adding data also from the more distant point L3 extends the longitudinal coverage much further. The additional vantage points also improve the visibility of the globally influential polar fields. Using a flux-transport model for the solar photospheric field, we model full-disk observations from Earth/L1, L3, L4, and L5 over a solar cycle, construct synoptic maps using a novel weighting scheme adapted for merging magnetogram data from multiple viewpoints, and compute potential-field models for the global coronal field. Each additional viewpoint brings the maps and models into closer agreement with the reference field from the flux-transport simulation, with particular improvement at polar latitudes, the main source of the fast solar wind.

The utility of polarized heliospheric imaging for space weather monitoring.

PubMed

DeForest, C E; Howard, T A; Webb, D F; Davies, J A

2016-01-01

A polarizing heliospheric imager is a critical next generation tool for space weather monitoring and prediction. Heliospheric imagers can track coronal mass ejections (CMEs) as they cross the solar system, using sunlight scattered by electrons in the CME. This tracking has been demonstrated to improve the forecasting of impact probability and arrival time for Earth-directed CMEs. Polarized imaging allows locating CMEs in three dimensions from a single vantage point. Recent advances in heliospheric imaging have demonstrated that a polarized imager is feasible with current component technology.Developing this technology to a high technology readiness level is critical for space weather relevant imaging from either a near-Earth or deep-space mission. In this primarily technical review, we developpreliminary hardware requirements for a space weather polarizing heliospheric imager system and outline possible ways to flight qualify and ultimately deploy the technology operationally on upcoming specific missions. We consider deployment as an instrument on NOAA's Deep Space Climate Observatory follow-on near the Sun-Earth L1 Lagrange point, as a stand-alone constellation of smallsats in low Earth orbit, or as an instrument located at the Sun-Earth L5 Lagrange point. The critical first step is the demonstration of the technology, in either a science or prototype operational mission context.

Tridimensional morphology and kinetics of etch pit on the {l_brace}0 0 0 1{r_brace} plane of sapphire crystal

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

Zhang Lunyong; Sun Jianfei, E-mail: jfsun_hit@263.net; Zuo Hongbo

2012-08-15

The tridimensional morphology and etching kinetics of the etch pit on the C-{l_brace}0 0 0 1{r_brace} plane of sapphire crystal ({alpha}-Al{sub 2}O{sub 3}) in molten KOH were studied experimentally. It was shown that the etch pit takes on tridimensional morphologies with triangular symmetry same as the symmetric property of the sapphire crystal. Pits like centric and eccentric triangular pyramid as well as hexagonal pyramid were observed, but the latter is less in density. In-depth analyses show the side walls of the etch pits belong to the {l_brace}1 1{sup Macron} 0 2{sup Macron }{r_brace} family, and the triangular pit contains edgesmore » full composed by Al{sup 3+} ions on the etching surface so it is more stable than the hexagonal pit since its edges on the etching surface contains Al{sup 2+} ions. The etch pits developed in a manner of kinematic wave by the step moving with constant speed, which is controlled by the chemical reaction with activation energy of 96.6 kJ/mol between Al{sub 2}O{sub 3} and KOH. - Graphical abstract: Schematic showing the atomic configuration of the predicted side walls of regular triangular pyramid shaped etch pit on the C-{l_brace}0 0 0 1{r_brace} plane of sapphire crystal. Highlights: Black-Right-Pointing-Pointer Observed the tridimensional morphology of etch pits. Black-Right-Pointing-Pointer Figured out the atomic configuration origin of the etch pits. Black-Right-Pointing-Pointer Quantitatively determined the etch rates of the etch pits.« less

Grid Effect on Spherical Shallow Water Jets Using Continuous and Discontinuous Galerkin Methods

DTIC Science & Technology

2013-01-01

The high-order Legendre -Gauss-Lobatto (LGL) points are added to the linear grid by projecting the linear elements onto the auxiliary gnomonic space...mapping, the triangles are subdivided into smaller ones by a Lagrange polynomial of order nI . The number of quadrilateral elements and grid points of...of the acceleration of gravity and the vertical height of the fluid), ν∇2 is the artificial viscosity term of viscous coefficient ν = 1× 105 m2 s−1

Dynamic analysis and control PID path of a model type gantry crane

NASA Astrophysics Data System (ADS)

Ospina-Henao, P. A.; López-Suspes, Framsol

2017-06-01

This paper presents an alternate form for the dynamic modelling of a mechanical system that simulates in real life a gantry crane type, using Euler’s classical mechanics and Lagrange formalism, which allows find the equations of motion that our model describe. Moreover, it has a basic model design system using the SolidWorks software, based on the material and dimensions of the model provides some physical variables necessary for modelling. In order to verify the theoretical results obtained, a contrast was made between solutions obtained by simulation in SimMechanics-Matlab and Euler-Lagrange equations system, has been solved through Matlab libraries for solving equation’s systems of the type and order obtained. The force is determined, but not as exerted by the spring, as this will be the control variable. The objective is to bring the mass of the pendulum from one point to another with a specified distance without the oscillation from it, so that, the answer is overdamped. This article includes an analysis of PID control in which the equations of motion of Euler-Lagrange are rewritten in the state space, once there, they were implemented in Simulink to get the natural response of the system to a step input in F and then draw the desired trajectories.

Dynamical Evolution of Planetesimals in the Outer Solar System. II. The Saturn/Uranus and Uranus/Neptune Zones

NASA Astrophysics Data System (ADS)

Grazier, Kevin R.; Newman, William I.; Varadi, Ferenc; Kaula, William M.; Hyman, James M.

1999-08-01

We report on numerical simulations exploring the dynamical stability of planetesimals in the gaps between the outer Solar System planets. We search for stable niches in the Saturn/Uranus and Uranus/Neptune zones by employing 10,000 massless particles-many more than previous studies in these two zones-using high-order optimized multistep integration schemes coupled with roundoff error minimizing methods. An additional feature of this study, differing from its predecessors, is the fact that our initial distributions contain particles on orbits which are both inclined and noncircular. These initial distributions were also Gaussian distributed such that the Gaussian peaks were at the midpoint between the neighboring perturbers. The simulations showed an initial transient phase where the bulk of the primordial planetesimal swarm was removed from the Solar System within 105 years. This is about 10 times longer than we observed in our previous Jupiter/Saturn studies. Next, there was a gravitational relaxation phase where the particles underwent a random walk in momentum space and were exponentially eliminated by random encounters with the planets. Unlike our previous Jupiter/Saturn simulation, the particles did not fully relax into a third Lagrangian niche phase where long-lived particles are at Lagrange points or stable niches. This is either because the Lagrangian niche phase never occurs or because these simulations did not have enough particles for this third phase to manifest. In these simulations, there was a general trend for the particles to migrate outward and eventually to be cleared out by the outermost planet in the zone. We confirmed that particles with higher eccentricities had shorter lifetimes and that the resonances between the jovian planets "pumped up" the eccentricities of the planetesimals with low-inclination orbits more than those with higher inclinations. We estimated the expected lifetime of particles using kinetic theory and even though the time scale of the Uranus/Neptune simulation was 380 times longer than our previous Jupiter/Saturn simulation, the planetesimals in the Uranus/Neptune zone were cleared out more quickly than those in the Saturn/Uranus zone because of the positions of resonances with the jovian planets. These resonances had an even greater effect than random gravitational stirring in the winnowing process and confirm that all the jovian planets are necessary in long simulations. Even though we observed several long-lived zones near 12.5, 14.4, 16, 24.5, and 26 AU, only two particles remained at the end of the 109-year integration: one near the 2 : 3 Saturn resonance, and the other near the Neptune 1 : 1 resonance. This suggests that niches for planetesimal material in the jovian planets are rare and may exist either only in extremely narrow bands or in the neighborhoods of the triangular Lagrange points of the outer planets.

A triangular thin shell finite element: Nonlinear analysis. [structural analysis

NASA Technical Reports Server (NTRS)

Thomas, G. R.; Gallagher, R. H.

1975-01-01

Aspects of the formulation of a triangular thin shell finite element which pertain to geometrically nonlinear (small strain, finite displacement) behavior are described. The procedure for solution of the resulting nonlinear algebraic equations combines a one-step incremental (tangent stiffness) approach with one iteration in the Newton-Raphson mode. A method is presented which permits a rational estimation of step size in this procedure. Limit points are calculated by means of a superposition scheme coupled to the incremental side of the solution procedure while bifurcation points are calculated through a process of interpolation of the determinants of the tangent-stiffness matrix. Numerical results are obtained for a flat plate and two curved shell problems and are compared with alternative solutions.

On the stability of triangular points in the relativistic R3BP when the bigger primary is oblate and the smaller one radiating with application on Cen X-4 binary system

NASA Astrophysics Data System (ADS)

Bello, Nakone; Umar, Aishetu

2018-06-01

In the framework of the relativistic R3BP, we examine the effects of oblateness of the primary body and radiation pressure of the secondary on the positions and stability of the triangular points L4,5. It is found that the parameters involved all affect the positions and increase in any of the parameters leads to a reduction in the size of the region of stability. Thus establishing their destabilizing tendencies. The presence of positive real roots or positive real part in complex roots affirms the instability of L4,5 of the problem when applied to Cen X-4.

Terahertz emission from the intrinsic Josephson junctions of high-symmetry thermally-managed Bi2Sr2CaCu2O8+δ microstrip antennas

NASA Astrophysics Data System (ADS)

Klemm, Richard A.; Davis, Andrew E.; Wang, Qing X.; Yamamoto, Takashi; Cerkoney, Daniel P.; Reid, Candy; Koopman, Maximiliaan L.; Minami, Hidetoshi; Kashiwagi, Takanari; Rain, Joseph R.; Doty, Constance M.; Sedlack, Michael A.; Morales, Manuel A.; Watanabe, Chiharu; Tsujimoto, Manabu; Delfanazari, Kaveh; Kadowaki, Kazuo

2017-12-01

We show for high-symmetry disk, square, or equilateral triangular thin microstrip antennas of any composition respectively obeying C ∞v , C 4v , and C 3v point group symmetries, that the transverse magnetic electromagnetic cavity mode wave functions are restricted in form to those that are one-dimensional representations of those point groups. Plots of the common nodal points of the ten lowest-energy non-radiating two-dimensional representations of each of these three symmetries are presented. For comparison with symmetry-broken disk intrinsic Josephson junction microstrip antennas constructed from the highly anisotropic layered superconductor Bi2Sr2CaCu2O8+δ (BSCCO), we present plots of the ten lowest frequency orthonormal wave functions and of their emission power angular distributions. These results are compared with previous results for square and equilateral triangular thin microstrip antennas.

Combined effect of oblateness, radiation and a circular cluster of material points on the stability of triangular liberation points in the R3BP

NASA Astrophysics Data System (ADS)

Singh, Jagadish; Taura, Joel John

2014-06-01

This paper studies the motion of an infinitesimal mass in the framework of the restricted three-body problem (R3BP) under the assumption that the primaries of the system are radiating-oblate spheroids, enclosed by a circular cluster of material points. It examines the effects of radiation and oblateness up to J 4 of the primaries and the potential created by the circular cluster, on the linear stability of the liberation locations of the infinitesimal mass. The liberation points are found to be stable for 0< μ< μ c and unstable for , where μ c is the critical mass value depending on terms which involve parameters that characterize the oblateness, radiation forces and the circular cluster of material points. The oblateness up to J 4 of the primaries and the gravitational potential from the circular cluster of material points have stabilizing propensities, while the radiation of the primaries and the oblateness up to J 2 of the primaries have destabilizing tendencies. The combined effect of these perturbations on the stability of the triangular liberation points is that, it has stabilizing propensity.

Motion in a modified Chermnykh's restricted three-body problem with oblateness

NASA Astrophysics Data System (ADS)

Singh, Jagadish; Leke, Oni

2014-03-01

In this paper, the restricted problem of three bodies is generalized to include a case when the passively gravitating test particle is an oblate spheroid under effect of small perturbations in the Coriolis and centrifugal forces when the first primary is a source of radiation and the second one an oblate spheroid, coupled with the influence of the gravitational potential from the belt. The equilibrium points are found and it is seen that, in addition to the usual three collinear equilibrium points, there appear two new ones due to the potential from the belt and the mass ratio. Two triangular equilibrium points exist. These equilibria are affected by radiation of the first primary, small perturbation in the centrifugal force, oblateness of both the test particle and second primary and the effect arising from the mass of the belt. The linear stability of the equilibrium points is explored and the stability outcome of the collinear equilibrium points remains unstable. In the case of the triangular points, motion is stable with respect to some conditions which depend on the critical mass parameter; influenced by the small perturbations, radiating effect of the first primary, oblateness of the test body and second primary and the gravitational potential from the belt. The effects of each of the imposed free parameters are analyzed. The potential from the belt and small perturbation in the Coriolis force are stabilizing parameters while radiation, small perturbation in the centrifugal force and oblateness reduce the stable regions. The overall effect is that the region of stable motion increases under the combine action of these parameters. We have also found the frequencies of the long and short periodic motion around stable triangular points. Illustrative numerical exploration is rendered in the Sun-Jupiter and Sun-Earth systems where we show that in reality, for some values of the system parameters, the additional equilibrium points do not in general exist even when there is a belt to interact with.

Polynomial expansions of single-mode motions around equilibrium points in the circular restricted three-body problem

NASA Astrophysics Data System (ADS)

Lei, Hanlun; Xu, Bo; Circi, Christian

2018-05-01

In this work, the single-mode motions around the collinear and triangular libration points in the circular restricted three-body problem are studied. To describe these motions, we adopt an invariant manifold approach, which states that a suitable pair of independent variables are taken as modal coordinates and the remaining state variables are expressed as polynomial series of them. Based on the invariant manifold approach, the general procedure on constructing polynomial expansions up to a certain order is outlined. Taking the Earth-Moon system as the example dynamical model, we construct the polynomial expansions up to the tenth order for the single-mode motions around collinear libration points, and up to order eight and six for the planar and vertical-periodic motions around triangular libration point, respectively. The application of the polynomial expansions constructed lies in that they can be used to determine the initial states for the single-mode motions around equilibrium points. To check the validity, the accuracy of initial states determined by the polynomial expansions is evaluated.

GPU surface extraction using the closest point embedding

NASA Astrophysics Data System (ADS)

Kim, Mark; Hansen, Charles

2015-01-01

Isosurface extraction is a fundamental technique used for both surface reconstruction and mesh generation. One method to extract well-formed isosurfaces is a particle system; unfortunately, particle systems can be slow. In this paper, we introduce an enhanced parallel particle system that uses the closest point embedding as the surface representation to speedup the particle system for isosurface extraction. The closest point embedding is used in the Closest Point Method (CPM), a technique that uses a standard three dimensional numerical PDE solver on two dimensional embedded surfaces. To fully take advantage of the closest point embedding, it is coupled with a Barnes-Hut tree code on the GPU. This new technique produces well-formed, conformal unstructured triangular and tetrahedral meshes from labeled multi-material volume datasets. Further, this new parallel implementation of the particle system is faster than any known methods for conformal multi-material mesh extraction. The resulting speed-ups gained in this implementation can reduce the time from labeled data to mesh from hours to minutes and benefits users, such as bioengineers, who employ triangular and tetrahedral meshes

Spacecraft Formation Flying near Sun-Earth L2 Lagrange Point: Trajectory Generation and Adaptive Full-State Feedback Control

NASA Technical Reports Server (NTRS)

Wong, Hong; Kapila, Vikram

2004-01-01

In this paper, we present a method for trajectory generation and adaptive full-state feedback control to facilitate spacecraft formation flying near the Sun-Earth L2 Lagrange point. Specifically, the dynamics of a spacecraft in the neighborhood of a Halo orbit reveals that there exist quasi-periodic orbits surrounding the Halo orbit. Thus, a spacecraft formation is created by placing a leader spacecraft on a desired Halo orbit and placing follower spacecraft on desired quasi-periodic orbits. To produce a formation maintenance controller, we first develop the nonlinear dynamics of a follower spacecraft relative to the leader spacecraft. We assume that the leader spacecraft is on a desired Halo orbit trajectory and the follower spacecraft is to track a desired quasi-periodic orbit surrounding the Halo orbit. Then, we design an adaptive, full-state feedback position tracking controller for the follower spacecraft providing an adaptive compensation for the unknown mass of the follower spacecraft. The proposed control law is simulated for the case of the leader and follower spacecraft pair and is shown to yield global, asymptotic convergence of the relative position tracking errors.

Dynamical evolution of a fictitious population of binary Neptune Trojans

NASA Astrophysics Data System (ADS)

Brunini, Adrián

2018-03-01

We present numerical simulations of the evolution of a synthetic population of Binary Neptune Trojans, under the influence of the solar perturbations and tidal friction (the so-called Kozai cycles and tidal friction evolution). Our model includes the dynamical influence of the four giant planets on the heliocentric orbit of the binary centre of mass. In this paper, we explore the evolution of initially tight binaries around the Neptune L4 Lagrange point. We found that the variation of the heliocentric orbital elements due to the libration around the Lagrange point introduces significant changes in the orbital evolution of the binaries. Collisional processes would not play a significant role in the dynamical evolution of Neptune Trojans. After 4.5 × 109 yr of evolution, ˜50 per cent of the synthetic systems end up separated as single objects, most of them with slow diurnal rotation rate. The final orbital distribution of the surviving binary systems is statistically similar to the one found for Kuiper Belt Binaries when collisional evolution is not included in the model. Systems composed by a primary and a small satellite are more fragile than the ones composed by components of similar sizes.

Transit detection of a `starshade' at the inner lagrange point of an exoplanet

NASA Astrophysics Data System (ADS)

Gaidos, E.

2017-08-01

All water-covered rocky planets in the inner habitable zones of solar-type stars will inevitably experience a catastrophic runaway climate due to increasing stellar luminosity and limits to outgoing infrared radiation from wet greenhouse atmospheres. Reflectors or scatterers placed near Earth's inner Lagrange point (L_1) have been proposed as a "geoengineering' solution to anthropogenic climate change and an advanced version of this could modulate incident irradiation over many Gyr or `rescue' a planet from the interior of the habitable zone. The distance of the starshade from the planet that minimizes its mass is 1.6 times the Earth-L_1 distance. Such a starshade would have to be similar in size to the planet and the mutual occultations during planetary transits could produce a characteristic maximum at mid-transit in the light curve. Because of a fortuitous ratio of densities, Earth-size planets around G dwarf stars present the best opportunity to detect such an artefact. The signal would be persistent and is potentially detectable by a future space photometry mission to characterize transiting planets. The signal could be distinguished from natural phenomenon, I.e. starspots or cometary dust clouds, by its shape, persistence and transmission spectrum.

Implicit Geometry Meshing for the simulation of Rotary Friction Welding

NASA Astrophysics Data System (ADS)

Schmicker, D.; Persson, P.-O.; Strackeljan, J.

2014-08-01

The simulation of Rotary Friction Welding (RFW) is a challenging task, since it states a coupled problem of phenomena like large plastic deformations, heat flux, contact and friction. In particular the mesh generation and its restoration when using a Lagrangian description of motion is of significant severity. In this regard Implicit Geometry Meshing (IGM) algorithms are promising alternatives to the more conventional explicit methods. Because of the implicit description of the geometry during remeshing, the IGM procedure turns out to be highly robust and generates spatial discretizations of high quality regardless of the complexity of the flash shape and its inclusions. A model for efficient RFW simulation is presented, which is based on a Carreau fluid law, an Augmented Lagrange approach in mapping the incompressible deformations, a penalty contact approach, a fully regularized Coulomb-/fluid friction law and a hybrid time integration strategy. The implementation of the IGM algorithm using 6-node triangular finite elements is described in detail. The techniques are demonstrated on a fairly complex friction welding problem, demonstrating the performance and the potentials of the proposed method. The techniques are general and straight-forward to implement, and offer the potential of successful adoption to a wide range of other engineering problems.

Searching for life with the Terrestrial Planet Finder: Lagrange point options for a formation flying interferometer

NASA Technical Reports Server (NTRS)

Beichman, C.; Gomez, G.; Lo, M.; Masdemont, J.; Romans, L.

2002-01-01

In this paper, we describe the mission design for TPF assuming a distributed spacecraft concept using formation flight around both a halo orbit around L2 as well as a heliocentric orbit. Although the mission architecture is still under study, the next two years will include study of four design cncepts and a downselect to two concepts around 2005.

Reconfirmation of the anatomy of the left triangular ligament and the appendix fibrosa hepatis in human livers, and its implication in abdominal surgery.

PubMed

Kogure, Kimitaka; Kojima, Itaru; Kuwano, Hiroyuki; Matsuzaki, Toshiyuki; Yorifuji, Hiroshi; Takata, Kuniaki; Makuuchi, Masatoshi

2014-12-01

The aim of the present study was to clarify the anatomy between the left triangular ligament (LTL) and the appendix fibrosa hepatis (AFH) in order not to sever the AFH when dissecting the LTL. Totals of 43 and 27 cadaveric livers were examined macroscopically and histologically, respectively. The LTL attached itself to the diaphragmatic surface of the AFH through almost all lengths of the AFH. This might be the reason why AFH is so often dissected together with the LTL. There were two types of relation between the LTL and the AFH; in one type, the starting point of the LTL existed on the left liver and in the other type, it was on the AFH. Twenty-five of 27 AFH included remnants of the bile duct and 12 of 25 AFH had comparatively large bile ducts, which was unexceptionally accompanied by the well-developed peribiliary vascular plexus. AFH showed a variety of shapes, such as rectangular (6/43), long triangular (4/43), short triangular (7/43), triangular plus cordlike (11/43), cordlike (12/43) and bifurcated (3/43) types. As AFH sometimes includes relatively large bile ducts, it is recommended for surgeons to sever the AFH not just simply by electrocautery but by ligating its stump securely. © 2014 Japanese Society of Hepato-Biliary-Pancreatic Surgery.

Sample Archaeological Survey of Public Use Areas, Milford Lake, Kansas

DTIC Science & Technology

1982-09-01

6,000 B.C. Llano -(Clovis projectile points) Lindenmeier - (Folsom projectile points) Plano -(Plainview, Angostora, Hell Gap, Scotts- bluff, etc...plain, flaring or S-form rims, shell tempered, plain surfaced pottery with low rolled rims 0 and incised alternating hatched triangles on the...tempered pottery with a marked collar rim incised with zig-zags, herringbone and hatched alternating triangles; unnotched triangular arrow points; French

Cavity mode enhancement of terahertz emission from equilateral triangular microstrip antennas of the high-Tc superconductor Bi2Sr2CaCu2O8+δ

NASA Astrophysics Data System (ADS)

Doty, Constance; Cerkoney, Daniel; Gramajo, Ashley; Campbell, Tyler; Reid, Candy; Morales, Manuel; Delfanazari, Kaveh; Yamamoto, Takashi; Tsujimoto, Manabu; Kashiwagi, Takanari; Watanabe, Chiharu; Minami, Hidetoshi; Kadowaki, Kazuo; Klemm, Richard

We study the transverse magnetic (TM) electromagnetic cavity mode wave functions for an ideal equilateral triangular microstrip antenna exhibiting C3v point group symmetry, which restricts the number of TM(n,m) modes to | m - n | = 3 p , where the integer p > 0 for the modes odd and even about the three mirror planes, but p = 0 can also exist for the even modes. We calculate the wave functions and the power distribution forms from the uniform Josephson current source and from the excitation of one of these cavity modes, and fit data on an early equilateral triangular Bi2Sr2CaCu2O8+δ mesa, for which the C3v symmetry was apparently broken. Work supported in part by the UCF RAMP, JSPS Fellowship, CREST-JST, and WPI-MANA.

Spin-Chirality-Driven Ferroelectricity on a Perfect Triangular Lattice Antiferromagnet

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

Mitamura, H.; Watanuki, R.; Kaneko, Koji

Magnetic field (B) variation of the electrical polarization P c ( ∥c) of the perfect triangular lattice antiferromagnet RbFe(MoO 4) 2 is examined up to the saturation point of the magnetization for B⊥c. P c is observed only in phases for which chirality is predicted in the in-plane magnetic structures. No strong anomaly is observed in P c at the field at which the spin modulation along the c axis, and hence the spin helicity, exhibits a discontinuity to the commensurate state. These results indicate that the ferroelectricity in this compound originates predominantly from the spin chirality, the explanation ofmore » which would require a new mechanism for magnetoferroelectricity. Lastly, the obtained field-temperature phase diagrams of ferroelectricity well agree with those theoretically predicted for the spin chirality of a Heisenberg spin triangular lattice antiferromagnet.« less

Spin-Chirality-Driven Ferroelectricity on a Perfect Triangular Lattice Antiferromagnet

DOE PAGES

Mitamura, H.; Watanuki, R.; Kaneko, Koji; ...

2014-10-01

Magnetic field (B) variation of the electrical polarization P c ( ∥c) of the perfect triangular lattice antiferromagnet RbFe(MoO 4) 2 is examined up to the saturation point of the magnetization for B⊥c. P c is observed only in phases for which chirality is predicted in the in-plane magnetic structures. No strong anomaly is observed in P c at the field at which the spin modulation along the c axis, and hence the spin helicity, exhibits a discontinuity to the commensurate state. These results indicate that the ferroelectricity in this compound originates predominantly from the spin chirality, the explanation ofmore » which would require a new mechanism for magnetoferroelectricity. Lastly, the obtained field-temperature phase diagrams of ferroelectricity well agree with those theoretically predicted for the spin chirality of a Heisenberg spin triangular lattice antiferromagnet.« less

Modified Lagrange invariants and their role in determining transverse and axial imaging resolutions of self-interference incoherent holographic systems.

PubMed

Rosen, Joseph; Kelner, Roy

2014-11-17

The Lagrange invariant is a well-known law for optical imaging systems formulated in the frame of ray optics. In this study, we reformulate this law in terms of wave optics and relate it to the resolution limits of various imaging systems. Furthermore, this modified Lagrange invariant is generalized for imaging along the z axis, resulting with the axial Lagrange invariant which can be used to analyze the axial resolution of various imaging systems. To demonstrate the effectiveness of the theory, analysis of the lateral and the axial imaging resolutions is provided for Fresnel incoherent correlation holography (FINCH) systems.

Investigations at Supersonic Speeds of 22 Triangular Wings Representing Two Airfoil Sections for Each of 11 Apex Angles

NASA Technical Reports Server (NTRS)

Love, Eugene S

1955-01-01

The results of tests of 22 triangular wings, representing two leading-edge shapes for each of 11 apex angles, at Mach numbers 1.62, 1.92, and 1.40 are presented and compared with theory. All wings have a common thickness ratio of 8 percent and a common maximum-thickness point at 18 percent chord. Lift, drag, and pitching moment are given for all wings at each Mach number. The relation of transition in the boundary layer, shocks on the wing surfaces, and characteristics of the pressure distributions is discussed for several wings.

Phase-plane analysis to an “anisotropic” higher-order traffic flow model

NASA Astrophysics Data System (ADS)

Wu, Chun-Xiu

2018-04-01

The qualitative theory of differential equations is applied to investigate the traveling wave solution to an “anisotropic” higher-order viscous traffic flow model under the Lagrange coordinate system. The types and stabilities of the equilibrium points are discussed in the phase plane. Through the numerical simulation, the overall distribution structures of trajectories are drawn to analyze the relation between the phase diagram and the selected conservative solution variables, and the influences of the parameters on the system are studied. The limit-circle, limit circle-spiral point, saddle-spiral point and saddle-nodal point solutions are obtained. These steady-state solutions provide good explanation for the phenomena of the oscillatory and homogeneous congestions in real-world traffic.

33 CFR 334.1125 - Pacific Ocean Naval Air Weapons Station, Point Mugu, Small Arms Range, Ventura County, California...

Code of Federal Regulations, 2014 CFR

2014-07-01

... Station, Point Mugu, Small Arms Range, Ventura County, California; danger zone. 334.1125 Section 334.1125 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE DANGER ZONE... Arms Range, Ventura County, California; danger zone. (a) The area. A triangular area extending...

33 CFR 334.1125 - Pacific Ocean Naval Air Weapons Station, Point Mugu, Small Arms Range, Ventura County, California...

Code of Federal Regulations, 2012 CFR

2012-07-01

... Station, Point Mugu, Small Arms Range, Ventura County, California; danger zone. 334.1125 Section 334.1125 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE DANGER ZONE... Arms Range, Ventura County, California; danger zone. (a) The area. A triangular area extending...

33 CFR 334.1125 - Pacific Ocean Naval Air Weapons Station, Point Mugu, Small Arms Range, Ventura County, California...

Code of Federal Regulations, 2013 CFR

2013-07-01

... Station, Point Mugu, Small Arms Range, Ventura County, California; danger zone. 334.1125 Section 334.1125 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE DANGER ZONE... Arms Range, Ventura County, California; danger zone. (a) The area. A triangular area extending...

Revisiting the Tale of Hercules: How Stars Orbiting the Lagrange Points Visit the Sun

NASA Astrophysics Data System (ADS)

Pérez-Villegas, Angeles; Portail, Matthieu; Wegg, Christopher; Gerhard, Ortwin

2017-05-01

We propose a novel explanation for the Hercules stream consistent with recent measurements of the extent and pattern speed of the Galactic bar. We have adapted a made-to-measure dynamical model tailored for the Milky Way to investigate the kinematics of the solar neighborhood (SNd). The model matches the 3D density of the red clump giant stars (RCGs) in the bulge and bar as well as stellar kinematics in the inner Galaxy, with a pattern speed of 39 km s-1 kpc-1. Cross-matching this model with the Gaia DR1 TGAS data combined with RAVE and LAMOST radial velocities, we find that the model naturally predicts a bimodality in the U-V-velocity distribution for nearby stars which is in good agreement with the Hercules stream. In the model, the Hercules stream is made of stars orbiting the Lagrange points of the bar which move outward from the bar’s corotation radius to visit the SNd. While the model is not yet a quantitative fit of the velocity distribution, the new picture naturally predicts that the Hercules stream is more prominent inward from the Sun and nearly absent only a few 100 pc outward of the Sun, and plausibly explains that Hercules is prominent in old and metal-rich stars.

Free time minimizers for the three-body problem

NASA Astrophysics Data System (ADS)

Moeckel, Richard; Montgomery, Richard; Sánchez Morgado, Héctor

2018-03-01

Free time minimizers of the action (called "semi-static" solutions by Mañe in International congress on dynamical systems in Montevideo (a tribute to Ricardo Mañé), vol 362, pp 120-131, 1996) play a central role in the theory of weak KAM solutions to the Hamilton-Jacobi equation (Fathi in Weak KAM Theorem in Lagrangian Dynamics Preliminary Version Number 10, 2017). We prove that any solution to Newton's three-body problem which is asymptotic to Lagrange's parabolic homothetic solution is eventually a free time minimizer. Conversely, we prove that every free time minimizer tends to Lagrange's solution, provided the mass ratios lie in a certain large open set of mass ratios. We were inspired by the work of Da Luz and Maderna (Math Proc Camb Philos Soc 156:209-227, 1980) which showed that every free time minimizer for the N-body problem is parabolic and therefore must be asymptotic to the set of central configurations. We exclude being asymptotic to Euler's central configurations by a second variation argument. Central configurations correspond to rest points for the McGehee blown-up dynamics. The large open set of mass ratios are those for which the linearized dynamics at each Euler rest point has a complex eigenvalue.

Connection forces in deformable multibody dynamics

NASA Technical Reports Server (NTRS)

Shabana, A. A.; Chang, C. W.

1989-01-01

In the dynamic formulation of holonomic and nonholonomic systems based on D'Alembert-Lagrange equation, the forces of constraints are maintained in the dynamic equations by introducing auxiliary variables, called Lagrange multipliers. This approach introduces a set of generalized reaction forces associated with the system generalized coordinates. Different sets of variables can be used as generalized coordinates and accordingly, the generalized reactions associated with these generalized coordinates may not be the actual reaction forces at the joints. In rigid body dynamics, the generalized reaction forces and the actual reaction forces at the joints represent equipollent systems of forces since they produce the same total forces and moments at and about any point on the rigid body. This is not, however, the case in deformable body analyses wherein the generalized reaction forces depend on the system generalized reference and elastic coordinates. In this paper, a method for determining the actual reaction forces at the joints from the generalized reaction forces in deformable multibody systems is presented.

Spin-Label CW Microwave Power Saturation and Rapid Passage with Triangular Non-Adiabatic Rapid Sweep (NARS) and Adiabatic Rapid Passage (ARP) EPR Spectroscopy

PubMed Central

Kittell, Aaron W.; Hyde, James S.

2015-01-01

Non-adiabatic rapid passage (NARS) electron paramagnetic resonance (EPR) spectroscopy was introduced by Kittell, A.W., Camenisch, T.G., Ratke, J.J. Sidabras, J.W., Hyde, J.S., 2011 as a general purpose technique to collect the pure absorption response. The technique has been used to improve sensitivity relative to sinusoidal magnetic field modulation, increase the range of inter-spin distances that can be measured under near physiological conditions, and enhance spectral resolution in copper (II) spectra. In the present work, the method is extended to CW microwave power saturation of spin-labeled T4 Lysozyme (T4L). As in the cited papers, rapid triangular sweep of the polarizing magnetic field was superimposed on slow sweep across the spectrum. Adiabatic rapid passage (ARP) effects were encountered in samples undergoing very slow rotational diffusion as the triangular magnetic field sweep rate was increased. The paper reports results of variation of experimental parameters at the interface of adiabatic and non-adiabatic rapid sweep conditions. Comparison of the forward (up) and reverse (down) triangular sweeps is shown to be a good indicator of the presence of rapid passage effects. Spectral turning points can be distinguished from spectral regions between turning points in two ways: differential microwave power saturation and differential passage effects. Oxygen accessibility data are shown under NARS conditions that appear similar to conventional field modulation data. However, the sensitivity is much higher, permitting, in principle, experiments at substantially lower protein concentrations. Spectral displays were obtained that appear sensitive to rotational diffusion in the range of rotational correlation times of 10−3 to 10−7 s in a manner that is analogous to saturation transfer spectroscopy. PMID:25917132

The Sun-Earth saddle point: characterization and opportunities to test general relativity

NASA Astrophysics Data System (ADS)

Topputo, Francesco; Dei Tos, Diogene A.; Rasotto, Mirco; Nakamiya, Masaki

2018-04-01

The saddle points are locations where the net gravitational accelerations balance. These regions are gathering more attention within the astrophysics community. Regions about the saddle points present clean, close-to-zero background acceleration environments where possible deviations from General Relativity can be tested and quantified. Their location suggests that flying through a saddle point can be accomplished by leveraging highly nonlinear orbits. In this paper, the geometrical and dynamical properties of the Sun-Earth saddle point are characterized. A systematic approach is devised to find ballistic orbits that experience one or multiple passages through this point. A parametric analysis is performed to consider spacecraft initially on L_{1,2} Lagrange point orbits. Sun-Earth saddle point ballistic fly-through trajectories are evaluated and classified for potential use. Results indicate an abundance of short-duration, regular solutions with a variety of characteristics.

A study of thin liquid sheet flows

NASA Technical Reports Server (NTRS)

Chubb, Donald L.; Calfo, Frederick D.; Mcconley, Marc W.; Mcmaster, Matthew S.; Afjeh, Abdollah A.

1993-01-01

This study was a theoretical and experimental investigation of thin liquid sheet flows in vacuum. A sheet flow created by a narrow slit of width, W, coalesces to a point at a distance, L, as a result of surface tension forces acting at the sheet edges. As the flow coalesces, the fluid accumulates in the sheet edges. The observed triangular shape of the sheet agrees with the calculated triangular result. Experimental results for L/W as a function of Weber number, We, agree with the calculated result, L/W = the sq. root of 8We. The edge cross sectional shape is found to oscillate from elliptic to 'cigar' like to 'peanut' like and then back to elliptic in the flow direction. A theoretical one-dimensional model was developed that yielded only elliptic solutions for the edge cross section. At the points where the elliptic shapes occur, there is agreement between theory and experiment.

Orbital Maneuvers for Spacecrafts Travelling to/from the Lagrangian Points

NASA Astrophysics Data System (ADS)

Bertachini, A.

The well-known Lagrangian points that appear in the planar restricted three-body problem (Szebehely, 1967) are very important for astronautical applications. They are five points of equilibrium in the equations of motion, what means that a particle located at one of those points with zero velocity will remain there indefinitely. The collinear points (L1, L2 and L3) are always unstable and the triangular points (L4 and L5) are stable in the present case studied (Sun-Earth system). They are all very good points to locate a space-station, since they require a small amount of V (and fuel), the control to be used for station-keeping. The triangular points are specially good for this purpose, since they are stable equilibrium points. In this paper, the planar restricted three-body problem is regularized (using Lemaître regularization) and combined with numerical integration and gradient methods to solve the two point boundary value problem (the Lambert's three-body problem). This combination is applied to the search of families of transfer orbits between the Lagrangian points and the Earth, in the Sun-Earth system, with the minimum possible cost of the control used. So, the final goal of this paper is to find the magnitude and direction of the two impulses to be applied in the spacecraft to complete the transfer: the first one when leaving/arriving at the Lagrangian point and the second one when arriving/living at the Earth. This paper is a continuation of two previous papers that studied transfers in the Earth-Moon system: Broucke (1979), that studied transfer orbits between the Lagrangian points and the Moon and Prado (1996), that studied transfer orbits between the Lagrangian points and the Earth. So, the equations of motion are: whereis the pseudo-potential given by: To solve the TPBVP in the regularized variables the following steps are used: i) Guess a initial velocity Vi, so together with the initial prescribed position ri the complete initial state is known; ii) Guess a final regularized time f and integrate the regularized equations of motion from 0 = 0 until f; iii) Check the final position rf obtained from the numerical integration with the prescribed final position and the final real time with the specified time of flight. If there is an agreement (difference less than a specified error allowed) the solution is found and the process can stop here. If there is no agreement, an increment in the initial guessed velocity Vi and in the guessed final regularized time is made and the process goes back to step i). The method used to find the increment in the guessed variables is the standard gradient method, as described in Press et. al., 1989. The routines available in this reference are also used in this research with minor modifications. After that this algorithm is implemented, the Lambert's three-body problem between the Earth and the Lagrangian points is solved for several values of the time of flight. Since the regularized system is used to solve this problem, there is no need to specify the final position of M3 as lying in an primary's parking orbit (to avoid the singularity). Then, to make a comparison with previous papers (Broucke, 1979 and Prado, 1996) the centre of the primary is used as the final position for M3. The results are organized in plots of the energy and the initial flight path angle (the control to be used) in the rotating frame against the time of flight. The definition of the angle is such that the zero is in the "x" axis, (pointing to the positive direction) and it increases in the counter-clock-wise sense. This problem, as well as the Lambert's original version, has two solutions for a given transfer time: one in the counter-clock-wise direction and one in the clock-wise direction in the inertial frame. In this paper, emphasis is given in finding the families with the smallest possible energy (and velocity), although many other families do exist. Broucke, R., (1979) Travelling Between the Lagrange Points and the Moon, Journal of Guidance and Control, Vol. 2, Prado, A.F.B.A., (1969) Travelling Between the Lagrangian Points and the Earth, Acta Astronautica, Vol. 39, No. 7, pp. Press, W. H.; B. P. Flannery; S. A. Teukolsky and W. T. Vetterling (1989), Numerical Recipes, Cambridge University Szebehely, V., (1967), Theory of Orbits, Academic Press, New York.

Low-energy transfers to cislunar periodic orbits visiting triangular libration points

NASA Astrophysics Data System (ADS)

Lei, Hanlun; Xu, Bo

2018-01-01

This paper investigates the cislunar periodic orbits that pass through triangular libration points of the Earth-Moon system and studies the techniques on design low-energy transfer trajectories. In order to compute periodic orbits, families of impulsive transfers between triangular libration points are taken to generate the initial guesses of periodic orbits, and multiple shooting techniques are applied to solving the problem. Then, varieties of periodic orbits in cislunar space are obtained, and stability analysis shows that the majority of them are unstable. Among these periodic orbits, an unstable periodic orbit in near 3:2 resonance with the Moon is taken as the nominal orbit of an assumed mission. As the stable manifolds of the target orbit could approach the Moon, low-energy transfer trajectories can be designed by combining lunar gravity assist with the invariant manifold structure of the target orbit. In practice, both the natural and perturbed invariant manifolds are considered to obtain the low-energy transfers, which are further refined to the Sun-perturbed Earth-Moon system. Results indicate that (a) compared to the case of natural invariant manifolds, the optimal transfers using perturbed invariant manifolds could reduce flight time at least 50 days, (b) compared to the cheapest direct transfer, the optimal low-energy transfer obtained by combining lunar gravity assist and invariant manifolds could save on-board fuel consumption more than 200 m/s, and (c) by taking advantage of the gravitational perturbation of the Sun, the low-energy transfers could save more fuel consumption than the corresponding ones obtained in the Earth-Moon system.

A new method for automated discontinuity trace mapping on rock mass 3D surface model

NASA Astrophysics Data System (ADS)

Li, Xiaojun; Chen, Jianqin; Zhu, Hehua

2016-04-01

This paper presents an automated discontinuity trace mapping method on a 3D surface model of rock mass. Feature points of discontinuity traces are first detected using the Normal Tensor Voting Theory, which is robust to noisy point cloud data. Discontinuity traces are then extracted from feature points in four steps: (1) trace feature point grouping, (2) trace segment growth, (3) trace segment connection, and (4) redundant trace segment removal. A sensitivity analysis is conducted to identify optimal values for the parameters used in the proposed method. The optimal triangular mesh element size is between 5 cm and 6 cm; the angle threshold in the trace segment growth step is between 70° and 90°; the angle threshold in the trace segment connection step is between 50° and 70°, and the distance threshold should be at least 15 times the mean triangular mesh element size. The method is applied to the excavation face trace mapping of a drill-and-blast tunnel. The results show that the proposed discontinuity trace mapping method is fast and effective and could be used as a supplement to traditional direct measurement of discontinuity traces.

Analytical and numerical construction of vertical periodic orbits about triangular libration points based on polynomial expansion relations among directions

NASA Astrophysics Data System (ADS)

Qian, Ying-Jing; Yang, Xiao-Dong; Zhai, Guan-Qiao; Zhang, Wei

2017-08-01

Innovated by the nonlinear modes concept in the vibrational dynamics, the vertical periodic orbits around the triangular libration points are revisited for the Circular Restricted Three-body Problem. The ζ -component motion is treated as the dominant motion and the ξ and η -component motions are treated as the slave motions. The slave motions are in nature related to the dominant motion through the approximate nonlinear polynomial expansions with respect to the ζ -position and ζ -velocity during the one of the periodic orbital motions. By employing the relations among the three directions, the three-dimensional system can be transferred into one-dimensional problem. Then the approximate three-dimensional vertical periodic solution can be analytically obtained by solving the dominant motion only on ζ -direction. To demonstrate the effectiveness of the proposed method, an accuracy study was carried out to validate the polynomial expansion (PE) method. As one of the applications, the invariant nonlinear relations in polynomial expansion form are used as constraints to obtain numerical solutions by differential correction. The nonlinear relations among the directions provide an alternative point of view to explore the overall dynamics of periodic orbits around libration points with general rules.

Integración automatizada de las ecuaciones de Lagrange en el movimiento orbital.

NASA Astrophysics Data System (ADS)

Abad, A.; San Juan, J. F.

The new techniques of algebraic manipulation, especially the Poisson Series Processor, permit the analytical integration of the more and more complex problems of celestial mechanics. The authors are developing a new Poisson Series Processor, PSPC, and they use it to solve the Lagrange equation of the orbital motion. They integrate the Lagrange equation by using the stroboscopic method, and apply it to the main problem of the artificial satellite theory.

Spin and charge controlled by antisymmetric spin-orbit coupling in a triangular-triple-quantum-dot Kondo system

NASA Astrophysics Data System (ADS)

Koga, M.; Matsumoto, M.; Kusunose, H.

2018-05-01

We study a local antisymmetric spin-orbit (ASO) coupling effect on a triangular-triple-quantum-dot (TTQD) system as a theoretical proposal for a new application of the Kondo physics to nanoscale devices. The electric polarization induced by the Kondo effect is strongly correlated with the spin configurations and molecular orbital degrees of freedom in the TTQD. In particular, an abrupt sign reversal of the emergent electric polarization is associated with a quantum critical point in a magnetic field, which can also be controlled by the ASO coupling that changes the mixing weight of different orbital components in the TTQD ground state.

Positional control of space robot manipulator

NASA Astrophysics Data System (ADS)

Kurochkin, Vladislav; Shymanchuk, Dzmitry

2018-05-01

In this article the mathematical model of a planar space robot manipulator is under study. The space robot manipulator represents a solid body with attached manipulators. The system of equations of motion is determined using the Lagrange's equations. The control problem concerning moving the robot to a given point and return it to a given trajectory in the phase space is solved. Changes of generalized coordinates and necessary control actions are plotted for a specific model.

Town Hall Meeting Presentation

NASA Technical Reports Server (NTRS)

Mather, John C.

2002-01-01

The James Webb Space Telescope (JWST), formerly known as the Next Generation Space Telescope (NGST), will be the successor to the Hubble Space Telescope. It will carry 3 instruments to a deep space orbit around the Sun-Earth Lagrange point L2, and will cover the wavelength range from 0.6 to 28 microns. The design concepts and current status of the project will be summarized, including the telescope and observatory contract proposed by the new prime contractor, TRW.

Weighted optimization of irradiance for photodynamic therapy of port wine stains

NASA Astrophysics Data System (ADS)

He, Linhuan; Zhou, Ya; Hu, Xiaoming

2016-10-01

Planning of irradiance distribution (PID) is one of the foremost factors for on-demand treatment of port wine stains (PWS) with photodynamic therapy (PDT). A weighted optimization method for PID was proposed according to the grading of PWS with a three dimensional digital illumination instrument. Firstly, the point clouds of lesions were filtered to remove the error or redundant points, the triangulation was carried out and the lesion was divided into small triangular patches. Secondly, the parameters such as area, normal vector and orthocenter for optimization of each triangular patch were calculated, and the weighted coefficients were determined by the erythema indexes and areas of patches. Then, the optimization initial point was calculated based on the normal vectors and orthocenters to optimize the light direction. In the end, the irradiation can be optimized according to cosine values of irradiance angles and weighted coefficients. Comparing the irradiance distribution before and after optimization, the proposed weighted optimization method can make the irradiance distribution match better with the characteristics of lesions, and has the potential to improve the therapeutic efficacy.

Aesthetic judgment of triangular shape: compactness and not the golden ratio determines perceived attractiveness

PubMed Central

Friedenberg, Jay

2012-01-01

Many studies over a period of more than a century have investigated the influence of the golden ratio on perceived geometric beauty. Surprisingly, very few of these studies used triangular shapes. In Experiment 1, we presented right triangles that differed in regard to their elongation determined by increasing the length of one side relative to another. Attractiveness ratings did not peak at the golden ratio, but there was a very strong influence of axis ratio overall. Participant ratings were a negative decreasing function of ratio. Triangles that pointed upward were judged as significantly more attractive than those that pointed down. We interpret these results according to a compactness hypothesis: triangles that are more compact are less likely to move or break and are thus considered more pleasing. Orientation also affects aesthetics. Upward-pointing triangles with a base parallel to the ground, regardless of their compactness, are also considered more perceptually stable and attractive. These findings were replicated across stimulus type in a second experiment with isosceles triangles and across testing procedure in a third experiment using a paired comparison technique. PMID:23145277

3D animation of facial plastic surgery based on computer graphics

NASA Astrophysics Data System (ADS)

Zhang, Zonghua; Zhao, Yan

2013-12-01

More and more people, especial women, are getting desired to be more beautiful than ever. To some extent, it becomes true because the plastic surgery of face was capable in the early 20th and even earlier as doctors just dealing with war injures of face. However, the effect of post-operation is not always satisfying since no animation could be seen by the patients beforehand. In this paper, by combining plastic surgery of face and computer graphics, a novel method of simulated appearance of post-operation will be given to demonstrate the modified face from different viewpoints. The 3D human face data are obtained by using 3D fringe pattern imaging systems and CT imaging systems and then converted into STL (STereo Lithography) file format. STL file is made up of small 3D triangular primitives. The triangular mesh can be reconstructed by using hash function. Top triangular meshes in depth out of numbers of triangles must be picked up by ray-casting technique. Mesh deformation is based on the front triangular mesh in the process of simulation, which deforms interest area instead of control points. Experiments on face model show that the proposed 3D animation facial plastic surgery can effectively demonstrate the simulated appearance of post-operation.

Competition between dynamic and structural disorder in a doped triangular antiferromagnet RbFe(MoO4)2

NASA Astrophysics Data System (ADS)

Smirnov, A. I.; Soldatov, T. A.; Petrenko, O. A.; Takata, A.; Kida, T.; Hagiwara, M.; Zhitomirsky, M. E.; Shapiro, A. Ya

2018-03-01

Magnetisation measurements and electron spin resonance (ESR) spectra of a doped quasi two dimensional (2D) antiferromagnet on a triangular lattice Rb1 ‑ x K x Fe(MoO4)2 reveal a crucial change of the ground state spin configuration and a disappearance of a characteristic 1/3-magnetisation plateau at x = 0.15. According to theory for triangular antiferromagnets with a weak random modulation of the exchange bonds, this is a result of the competition between the structural and dynamic disorders. The dynamic zero-point or thermal fluctuations are known to lift the degeneracy of the mean field ground state of a triangular antiferromagnet and cause the spin configuration to be the most collinear, while the static disorder provides another selection of the ground state, with the least collinear structure. Low-level doping (x ≤ 0.15) was found to decrease the Néel temperature and saturation field by only few percent, while the magnetisation plateau disappears completely and the spin configuration is drastically changed. ESR spectra confirm an impurity-induced change of the so-called Y-type structure to an inverted Y-structure for x = 0.15. For x = 0.075 the intermediate regime with the decrease of width and weakening of flattening of 1/3-plateau was found.

A free boundary approach to the Rosensweig instability of ferrofluids

NASA Astrophysics Data System (ADS)

Parini, Enea; Stylianou, Athanasios

2018-04-01

We establish the existence of saddle points for a free boundary problem describing the two-dimensional free surface of a ferrofluid undergoing normal field instability. The starting point is the ferrohydrostatic equations for the magnetic potentials in the ferrofluid and air, and the function describing their interface. These constitute the strong form for the Euler-Lagrange equations of a convex-concave functional, which we extend to include interfaces that are not necessarily graphs of functions. Saddle points are then found by iterating the direct method of the calculus of variations and applying classical results of convex analysis. For the existence part, we assume a general nonlinear magnetization law; for a linear law, we also show, via convex duality, that the saddle point is a constrained minimizer of the relevant energy functional.

1. EXTERIOR VIEW OF 209 WARE STREET LOOKING SOUTH. THIS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. EXTERIOR VIEW OF 209 WARE STREET LOOKING SOUTH. THIS STRUCTURE WAS ONE OF APPROXIMATELY SEVENTEEN DUPLEXES BUILT AS THE ORIGINAL WORKER HOUSING FOR THE LaGRANGE COTTON MILLS, LATER KNOWN AS CALUMET MILL. LaGRANGE MILLS (1888-89) WAS THE FIRST COTTON MILL IN LaGRANGE. NOTE THE GABLE-ON-HIP ROOF FORM AND TWO IDENTICAL STRUCTURES VISIBLE TO THE LEFT. - 209 Ware Street (House), 209 Ware Street, La Grange, Troup County, GA

Accuracy of Lagrange-sinc functions as a basis set for electronic structure calculations of atoms and molecules

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

Choi, Sunghwan; Hong, Kwangwoo; Kim, Jaewook

2015-03-07

We developed a self-consistent field program based on Kohn-Sham density functional theory using Lagrange-sinc functions as a basis set and examined its numerical accuracy for atoms and molecules through comparison with the results of Gaussian basis sets. The result of the Kohn-Sham inversion formula from the Lagrange-sinc basis set manifests that the pseudopotential method is essential for cost-effective calculations. The Lagrange-sinc basis set shows faster convergence of the kinetic and correlation energies of benzene as its size increases than the finite difference method does, though both share the same uniform grid. Using a scaling factor smaller than or equal tomore » 0.226 bohr and pseudopotentials with nonlinear core correction, its accuracy for the atomization energies of the G2-1 set is comparable to all-electron complete basis set limits (mean absolute deviation ≤1 kcal/mol). The same basis set also shows small mean absolute deviations in the ionization energies, electron affinities, and static polarizabilities of atoms in the G2-1 set. In particular, the Lagrange-sinc basis set shows high accuracy with rapid convergence in describing density or orbital changes by an external electric field. Moreover, the Lagrange-sinc basis set can readily improve its accuracy toward a complete basis set limit by simply decreasing the scaling factor regardless of systems.« less

Variational Integrators for Interconnected Lagrange-Dirac Systems

NASA Astrophysics Data System (ADS)

Parks, Helen; Leok, Melvin

2017-10-01

Interconnected systems are an important class of mathematical models, as they allow for the construction of complex, hierarchical, multiphysics, and multiscale models by the interconnection of simpler subsystems. Lagrange-Dirac mechanical systems provide a broad category of mathematical models that are closed under interconnection, and in this paper, we develop a framework for the interconnection of discrete Lagrange-Dirac mechanical systems, with a view toward constructing geometric structure-preserving discretizations of interconnected systems. This work builds on previous work on the interconnection of continuous Lagrange-Dirac systems (Jacobs and Yoshimura in J Geom Mech 6(1):67-98, 2014) and discrete Dirac variational integrators (Leok and Ohsawa in Found Comput Math 11(5), 529-562, 2011). We test our results by simulating some of the continuous examples given in Jacobs and Yoshimura (2014).

1. STREETSCAPE VIEW OF 208 VINE STREET (FIRST HOUSE ON ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. STREETSCAPE VIEW OF 208 VINE STREET (FIRST HOUSE ON RIGHT) LOOKING WEST. THIS STRUCTURE WAS ONE OF APPROXIMATELY SEVENTEEN DUPLEXES BUILT AS THE ORIGINAL WORKER HOUSING FOR THE LaGRANGE COTTON MILLS, LATER KNOWN AS CALUMET MILL. LaGRANGE MILLS (1888-89) WAS THE FIRST COTTON MILL IN LaGRANGE. NOTE THE GABLE-ON-HIP ROOF FORM AND IDENTICAL STRUCTURES FACING EACH OTHER ALONG BOTH SIDES OF THE NARROW STREET. - 208 Vine Street (House), 208 Vine Street, La Grange, Troup County, GA

Spacecraft Conceptual Design for the 8-Meter Advanced Technology Large Aperture Space Telescope (ATLAST)

NASA Technical Reports Server (NTRS)

Hopkins, Randall C.; Capizzo, Peter; Fincher, Sharon; Hornsby, Linda S.; Jones, David

2010-01-01

The Advanced Concepts Office at Marshall Space Flight Center completed a brief spacecraft design study for the 8-meter monolithic Advanced Technology Large Aperture Space Telescope (ATLAST-8m). This spacecraft concept provides all power, communication, telemetry, avionics, guidance and control, and thermal control for the observatory, and inserts the observatory into a halo orbit about the second Sun-Earth Lagrange point. The multidisciplinary design team created a simple spacecraft design that enables component and science instrument servicing, employs articulating solar panels for help with momentum management, and provides precise pointing control while at the same time fast slewing for the observatory.

LAGRANGE: LAser GRavitational-wave ANtenna in GEodetic Orbit

NASA Astrophysics Data System (ADS)

Buchman, S.; Conklin, J. W.; Balakrishnan, K.; Aguero, V.; Alfauwaz, A.; Aljadaan, A.; Almajed, M.; Altwaijry, H.; Saud, T. A.; Byer, R. L.; Bower, K.; Costello, B.; Cutler, G. D.; DeBra, D. B.; Faied, D. M.; Foster, C.; Genova, A. L.; Hanson, J.; Hooper, K.; Hultgren, E.; Klavins, A.; Lantz, B.; Lipa, J. A.; Palmer, A.; Plante, B.; Sanchez, H. S.; Saraf, S.; Schaechter, D.; Shu, K.; Smith, E.; Tenerelli, D.; Vanbezooijen, R.; Vasudevan, G.; Williams, S. D.; Worden, S. P.; Zhou, J.; Zoellner, A.

2013-01-01

We describe a new space gravitational wave observatory design called LAG-RANGE that maintains all important LISA science at about half the cost and with reduced technical risk. It consists of three drag-free spacecraft in a geocentric formation. Fixed antennas allow continuous contact with the Earth, solving the problem of communications bandwidth and latency. A 70 mm diameter sphere with a 35 mm gap to its enclosure serves as the single inertial reference per spacecraft, operating in “true” drag-free mode (no test mass forcing). Other advantages are: a simple caging design based on the DISCOS 1972 drag-free mission, an all optical read-out with pm fine and nm coarse sensors, and the extensive technology heritage from the Honeywell gyroscopes, and the DISCOS and Gravity Probe B drag-free sensors. An Interferometric Measurement System, designed with reflective optics and a highly stabilized frequency standard, performs the ranging between test masses and requires a single optical bench with one laser per spacecraft. Two 20 cm diameter telescopes per spacecraft, each with infield pointing, incorporate novel technology developed for advanced optical systems by Lockheed Martin, who also designed the spacecraft based on a multi-flight proven bus structure. Additional technological advancements include updated drag-free propulsion, thermal control, charge management systems, and materials. LAGRANGE subsystems are designed to be scalable and modular, making them interchangeable with those of LISA or other gravitational science missions. We plan to space qualify critical technologies on small and nano satellite flights, with the first launch (UV-LED Sat) in 2013.

Structure and Reversibility of 2D von Neumann Cellular Automata Over Triangular Lattice

NASA Astrophysics Data System (ADS)

Uguz, Selman; Redjepov, Shovkat; Acar, Ecem; Akin, Hasan

2017-06-01

Even though the fundamental main structure of cellular automata (CA) is a discrete special model, the global behaviors at many iterative times and on big scales could be a close, nearly a continuous, model system. CA theory is a very rich and useful phenomena of dynamical model that focuses on the local information being relayed to the neighboring cells to produce CA global behaviors. The mathematical points of the basic model imply the computable values of the mathematical structure of CA. After modeling the CA structure, an important problem is to be able to move forwards and backwards on CA to understand their behaviors in more elegant ways. A possible case is when CA is to be a reversible one. In this paper, we investigate the structure and the reversibility of two-dimensional (2D) finite, linear, triangular von Neumann CA with null boundary case. It is considered on ternary field ℤ3 (i.e. 3-state). We obtain their transition rule matrices for each special case. For given special triangular information (transition) rule matrices, we prove which triangular linear 2D von Neumann CAs are reversible or not. It is known that the reversibility cases of 2D CA are generally a much challenged problem. In the present study, the reversibility problem of 2D triangular, linear von Neumann CA with null boundary is resolved completely over ternary field. As far as we know, there is no structure and reversibility study of von Neumann 2D linear CA on triangular lattice in the literature. Due to the main CA structures being sufficiently simple to investigate in mathematical ways, and also very complex to obtain in chaotic systems, it is believed that the present construction can be applied to many areas related to these CA using any other transition rules.

Transition-metal oxides with triangular lattices: generation of new magnetic and electronic properties.

PubMed

Maignan, A; Kobayashi, W; Hébert, S; Martinet, G; Pelloquin, D; Bellido, N; Simon, Ch

2008-10-06

The search for multifunctional materials as multiferroics to be applied in microelectronic or for new, chemically stable and nontoxic, thermoelectric materials to recover waste heat is showing a common interest in the oxides whose structures contain a triangular network of transition-metal cations. To illustrate this point, two ternary systems, Ba-Co-O and Ca-Co-O, have been chosen. It is shown that new phases with a complex triangular structure can be discovered, for instance, by introduction of Ga (3+) into the Ba-Co-O system to stabilize Ba 6Ga 2Co 11O 26 and Ba 2GaCo 8O 14, which both belong to a large family of compounds with formula [Ba(Co,Ga)O 3-delta] n [BaCo 8O 11]. In the latter, both sublattices contain triangular networks derived from the hexagonal perovskite and the spinel structure. Among the hexagonal perovskite, the Ca 3Co 2O 6 crystals give clear evidence where the coupling of charges and spins is at the origin of a magnetocapacitance effect. In particular, the ferrimagnetic to ferromagnetic transition, with a one-third plateau on the M( H) curve characteristic of triangular magnetism, is accompanied by a peak in the dielectric constant. A second class of cobaltites is the focus of much interest. Their 2D structure, containing CoO 2 planes isostructural to a CdI 2 slice that are stacked in an incommensurate way with rock salt type layers, is referred to misfit cobaltite. The 2D triangular network of edge-shared CoO 6 octahedra is believed to be responsible for large values of the Seebeck coefficient and low electrical resistivity. A clear relationship between the structuresincommensurability ratiosand the electronic properties is evidenced, showing that the charge carrier concentration can be tuned via the control of the ionic radius of the cations in the separating layers.

Existence and instability of steady states for a triangular cross-diffusion system: A computer-assisted proof

NASA Astrophysics Data System (ADS)

Breden, Maxime; Castelli, Roberto

2018-05-01

In this paper, we present and apply a computer-assisted method to study steady states of a triangular cross-diffusion system. Our approach consist in an a posteriori validation procedure, that is based on using a fixed point argument around a numerically computed solution, in the spirit of the Newton-Kantorovich theorem. It allows to prove the existence of various non homogeneous steady states for different parameter values. In some situations, we obtain as many as 13 coexisting steady states. We also apply the a posteriori validation procedure to study the linear stability of the obtained steady states, proving that many of them are in fact unstable.

Emittance Measurements for a Thin Liquid Sheet Flow

NASA Technical Reports Server (NTRS)

Englehart, Amy N.; McConley, Marc W.; Chubb, Donald L.

1996-01-01

The Liquid Sheet Radiator (LSR) is an external flow radiator that uses a triangular-shaped flowing liquid sheet as the radiating surface. It has potentially much lower mass than solid wall radiators such as pumped loop and heat pipe radiators, along with being nearly immune to micrometeoroid penetration. The LSR has an added advantage of simplicity. Surface tension causes a thin (100-300 microns) liquid sheet to coalesce to a point, causing the sheet flow to have a triangular shape. Such a triangular sheet is desirable since it allows for simple collection of the flow at a single point. A major problem for all external flow radiators is the requirement that the working fluid be of very low (approx. 10(sup -8) torr) vapor pressure to keep evaporative losses low. As a result, working fluids are limited to certain oils (such as used in diffusion pumps) for low temperatures (300-400 K) and liquid metals for higher temperatures. Previous research on the LSR has been directed at understanding the fluid mechanics of thin sheet flows and assessing the stability of such flows, especially with regard to the formation of holes in the sheet. Taylor studied extensively the stability of thin liquid sheets both theoretically and experimentally. He showed that thin sheets in a vacuum are stable. The latest research has been directed at determining the emittance of thin sheet flows. The emittance was calculated from spectral transmittance data for the Dow Corning 705 silicone oil. By experimentally setting up a sheet flow, the emittance was also determined as a function of measurable quantities, most importantly, the temperature drop between the top of the sheet and the temperature at the coalescence point of the sheet. Temperature fluctuations upstream of the liquid sheet were a potential problem in the analysis and were investigated.

Normalization of Hamiltonian and nonlinear stability of the triangular equilibrium points in non-resonance case with perturbations

NASA Astrophysics Data System (ADS)

Kishor, Ram; Kushvah, Badam Singh

2017-09-01

For the study of nonlinear stability of a dynamical system, normalized Hamiltonian of the system is very important to discuss the dynamics in the vicinity of invariant objects. In general, it represents a nonlinear approximation to the dynamics, which is very helpful to obtain the information as regards a realistic solution of the problem. In the present study, normalization of the Hamiltonian and analysis of nonlinear stability in non-resonance case, in the Chermnykh-like problem under the influence of perturbations in the form of radiation pressure, oblateness, and a disc is performed. To describe nonlinear stability, initially, quadratic part of the Hamiltonian is normalized in the neighborhood of triangular equilibrium point and then higher order normalization is performed by computing the fourth order normalized Hamiltonian with the help of Lie transforms. In non-resonance case, nonlinear stability of the system is discussed using the Arnold-Moser theorem. Again, the effects of radiation pressure, oblateness and the presence of the disc are analyzed separately and it is observed that in the absence as well as presence of perturbation parameters, triangular equilibrium point is unstable in the nonlinear sense within the stability range 0<μ<μ1=\\bar{μc} due to failure of the Arnold-Moser theorem. However, perturbation parameters affect the values of μ at which D4=0, significantly. This study may help to analyze more generalized cases of the problem in the presence of some other types of perturbations such as P-R drag and solar wind drag. The results are limited to the regular symmetric disc but it can be extended in the future.

The Numerical Simulation of the Shock Wave of Coal Gas Explosions in Gas Pipe*

NASA Astrophysics Data System (ADS)

Chen, Zhenxing; Hou, Kepeng; Chen, Longwei

2018-03-01

For the problem of large deformation and vortex, the method of Euler and Lagrange has both advantage and disadvantage. In this paper we adopt special fuzzy interface method(volume of fluid). Gas satisfies the conditions of conservation equations of mass, momentum, and energy. Based on explosion and three-dimension fluid dynamics theory, using unsteady, compressible, inviscid hydrodynamic equations and state equations, this paper considers pressure gradient’s effects to velocity, mass and energy in Lagrange steps by the finite difference method. To minimize transport errors of material, energy and volume in Finite Difference mesh, it also considers material transport in Euler steps. Programmed with Fortran PowerStation 4.0 and visualized with the software designed independently, we design the numerical simulation of gas explosion with specific pipeline structure, check the key points of the pressure change in the flow field, reproduce the gas explosion in pipeline of shock wave propagation, from the initial development, flame and accelerate the process of shock wave. This offers beneficial reference and experience to coal gas explosion accidents or safety precautions.

COMMENTS ON THE PAPER 'ON THE STABILITY OF TRIANGULAR LAGRANGIAN POINTS IN THE RESTRICTED THREE-BODY PROBLEM' (2008, AJ, 135, 187)

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

Ivanov, A. P.

2009-06-15

In the referenced paper an analytical approach was introduced, which allows one to demonstrate the instability in linearly stable systems, specifically, in a classical three-body problem. These considerations are disproved here.

ELAS: A general-purpose computer program for the equilibrium problems of linear structures. Volume 2: Documentation of the program. [subroutines and flow charts

NASA Technical Reports Server (NTRS)

Utku, S.

1969-01-01

A general purpose digital computer program for the in-core solution of linear equilibrium problems of structural mechanics is documented. The program requires minimum input for the description of the problem. The solution is obtained by means of the displacement method and the finite element technique. Almost any geometry and structure may be handled because of the availability of linear, triangular, quadrilateral, tetrahedral, hexahedral, conical, triangular torus, and quadrilateral torus elements. The assumption of piecewise linear deflection distribution insures monotonic convergence of the deflections from the stiffer side with decreasing mesh size. The stresses are provided by the best-fit strain tensors in the least squares at the mesh points where the deflections are given. The selection of local coordinate systems whenever necessary is automatic. The core memory is used by means of dynamic memory allocation, an optional mesh-point relabelling scheme and imposition of the boundary conditions during the assembly time.

Grey-Markov prediction model based on background value optimization and central-point triangular whitenization weight function

NASA Astrophysics Data System (ADS)

Ye, Jing; Dang, Yaoguo; Li, Bingjun

2018-01-01

Grey-Markov forecasting model is a combination of grey prediction model and Markov chain which show obvious optimization effects for data sequences with characteristics of non-stationary and volatility. However, the state division process in traditional Grey-Markov forecasting model is mostly based on subjective real numbers that immediately affects the accuracy of forecasting values. To seek the solution, this paper introduces the central-point triangular whitenization weight function in state division to calculate possibilities of research values in each state which reflect preference degrees in different states in an objective way. On the other hand, background value optimization is applied in the traditional grey model to generate better fitting data. By this means, the improved Grey-Markov forecasting model is built. Finally, taking the grain production in Henan Province as an example, it verifies this model's validity by comparing with GM(1,1) based on background value optimization and the traditional Grey-Markov forecasting model.

Design and characterization of planar capacitive imaging probe based on the measurement sensitivity distribution

NASA Astrophysics Data System (ADS)

Yin, X.; Chen, G.; Li, W.; Huthchins, D. A.

2013-01-01

Previous work indicated that the capacitive imaging (CI) technique is a useful NDE tool which can be used on a wide range of materials, including metals, glass/carbon fibre composite materials and concrete. The imaging performance of the CI technique for a given application is determined by design parameters and characteristics of the CI probe. In this paper, a rapid method for calculating the whole probe sensitivity distribution based on the finite element model (FEM) is presented to provide a direct view of the imaging capabilities of the planar CI probe. Sensitivity distributions of CI probes with different geometries were obtained. Influencing factors on sensitivity distribution were studied. Comparisons between CI probes with point-to-point triangular electrode pair and back-to-back triangular electrode pair were made based on the analysis of the corresponding sensitivity distributions. The results indicated that the sensitivity distribution could be useful for optimising the probe design parameters and predicting the imaging performance.

Cause and Cure - Deterioration in Accuracy of CFD Simulations with Use of High-Aspect-Ratio Triangular/Tetrahedral Grids

NASA Technical Reports Server (NTRS)

Chang, Sin-Chung; Chang, Chau-Lyan; Venkatachari, Balaji Shankar

2017-01-01

Traditionally high-aspect ratio triangular/tetrahedral meshes are avoided by CFD researchers in the vicinity of a solid wall, as it is known to reduce the accuracy of gradient computations in those regions. Although for certain complex geometries, the use of high-aspect ratio triangular/tetrahedral elements in the vicinity of a solid wall can be replaced by quadrilateral/prismatic elements, ability to use triangular/tetrahedral elements in such regions without any degradation in accuracy can be beneficial from a mesh generation point of view. The benefits also carry over to numerical frameworks such as the space-time conservation element and solution element (CESE), where simplex elements are the mandatory building blocks. With the requirement of the CESE method in mind, a rigorous mathematical framework that clearly identifies the reason behind the difficulties in use of such high-aspect ratio simplex elements is formulated using two different approaches and presented here. Drawing insights from the analysis, a potential solution to avoid that pitfall is also provided as part of this work. Furthermore, through the use of numerical simulations of practical viscous problems involving high-Reynolds number flows, how the gradient evaluation procedures of the CESE framework can be effectively used to produce accurate and stable results on such high-aspect ratio simplex meshes is also showcased.

Scale-Limited Lagrange Stability and Finite-Time Synchronization for Memristive Recurrent Neural Networks on Time Scales.

PubMed

Xiao, Qiang; Zeng, Zhigang

2017-10-01

The existed results of Lagrange stability and finite-time synchronization for memristive recurrent neural networks (MRNNs) are scale-free on time evolvement, and some restrictions appear naturally. In this paper, two novel scale-limited comparison principles are established by means of inequality techniques and induction principle on time scales. Then the results concerning Lagrange stability and global finite-time synchronization of MRNNs on time scales are obtained. Scaled-limited Lagrange stability criteria are derived, in detail, via nonsmooth analysis and theory of time scales. Moreover, novel criteria for achieving the global finite-time synchronization are acquired. In addition, the derived method can also be used to study global finite-time stabilization. The proposed results extend or improve the existed ones in the literatures. Two numerical examples are chosen to show the effectiveness of the obtained results.

Analytical Dynamics and Nonrigid Spacecraft Simulation

NASA Technical Reports Server (NTRS)

Likins, P. W.

1974-01-01

Application to the simulation of idealized spacecraft are considered both for multiple-rigid-body models and for models consisting of combination of rigid bodies and elastic bodies, with the elastic bodies being defined either as continua, as finite-element systems, or as a collection of given modal data. Several specific examples are developed in detail by alternative methods of analytical mechanics, and results are compared to a Newton-Euler formulation. The following methods are developed from d'Alembert's principle in vector form: (1) Lagrange's form of d'Alembert's principle for independent generalized coordinates; (2) Lagrange's form of d'Alembert's principle for simply constrained systems; (3) Kane's quasi-coordinate formulation of D'Alembert's principle; (4) Lagrange's equations for independent generalized coordinates; (5) Lagrange's equations for simply constrained systems; (6) Lagrangian quasi-coordinate equations (or the Boltzmann-Hamel equations); (7) Hamilton's equations for simply constrained systems; and (8) Hamilton's equations for independent generalized coordinates.

Impacts of Sigma Coordinates on the Euler and Navier-Stokes Equations using Continuous Galerkin Methods

DTIC Science & Technology

2009-03-01

the 1- D local basis functions. The 1-D Lagrange polynomial local basis function, using Legendre -Gauss-Lobatto interpolation points, was defined by...cases were run using 10th order polynomials , with contours from -0.05 to 0.525 K with an interval of 0.025 K...after 700 s for reso- lutions: (a) 20, (b) 10, and (c) 5 m. All cases were run using 10th order polynomials , with contours from -0.05 to 0.525 K

Advances in Highly Constrained Multi-Phase Trajectory Generation using the General Pseudospectral Optimization Software (GPOPS)

DTIC Science & Technology

2013-08-01

release; distribution unlimited. PA Number 412-TW-PA-13395 f generic function g acceleration due to gravity h altitude L aerodynamic lift force L Lagrange...cost m vehicle mass M Mach number n number of coefficients in polynomial regression p highest order of polynomial regression Q dynamic pressure R...Method (RPM); the collocation points are defined by the roots of Legendre -Gauss- Radau (LGR) functions.9 GPOPS also automatically refines the “mesh” by

The Rényi entanglement entropy of a general quantum dimer model at the RK point: a highly efficient algorithm.

PubMed

Pei, Jiquan; Han, Steve; Liao, Haijun; Li, Tao

2014-01-22

A highly efficient and simple-to-implement Monte Carlo algorithm is proposed for the evaluation of the Rényi entanglement entropy (REE) of the quantum dimer model (QDM) at the Rokhsar-Kivelson (RK) point. It makes possible the evaluation of REE at the RK point to the thermodynamic limit for a general QDM. We apply the algorithm to a QDM defined on the triangular and the square lattice in two dimensions and the simple and the face centered cubic (fcc) lattice in three dimensions. We find the REE on all these lattices follows perfect linear scaling in the thermodynamic limit, apart from an even-odd oscillation in the case of the square lattice. We also evaluate the topological entanglement entropy (TEE) with both a subtraction and an extrapolation procedure. We find the QDMs on both the triangular and the fcc lattice exhibit robust Z2 topological order. The expected TEE of ln2 is clearly demonstrated in both cases. Our large scale simulation also proves the recently proposed extrapolation procedure in cylindrical geometry to be a highly reliable way to extract the TEE of a topologically ordered system.

A new standing-wave-type linear ultrasonic motor based on in-plane modes.

PubMed

Shi, Yunlai; Zhao, Chunsheng

2011-05-01

This paper presents a new standing-wave-type linear ultrasonic motor using combination of the first longitudinal and the second bending modes. Two piezoelectric plates in combination with a metal thin plate are used to construct the stator. The superior point of the stator is its isosceles triangular structure part of the stator, which can amplify the displacement in horizontal direction of the stator in perpendicular direction when the stator is operated in the first longitudinal mode. The influence of the base angle θ of the triangular structure part on the amplitude of the driving foot has been analyzed by numerical analysis. Four prototype stators with different angles θ have been fabricated and the experimental investigation of these stators has validated the numerical simulation. The overall dimensions of the prototype stators are no more than 40 mm (length) × 20 mm (width) × 5 mm (thickness). Driven by an AC signal with the driving frequency of 53.3 kHz, the no-load speed and the maximal thrust of the prototype motor using the stator with base angle 20° were 98 mm/s and 3.2N, respectively. The effective elliptical motion trajectory of the contact point of the stator can be achieved by the isosceles triangular structure part using only two PZTs, and thus it makes the motor low cost in fabrication, simple in structure and easy to realize miniaturization. Copyright © 2010 Elsevier B.V. All rights reserved.

Large area multi-channel plasmonic absorber based on the touching triangular dimers fabricated by angle controlled colloidal nanolithography

NASA Astrophysics Data System (ADS)

Hamidi, S. M.; Behjati, S.

2018-02-01

Here we introduce large area plasmonic touching triangular dimers by angle controlled colloidal nanolithography to use them as an efficient multi channel absorber and also high figure of merit sensors. For this purpose, we coated gold thin films onto nanometric and also micrometric polystyrene hexagonal closed packed masks in different deposition angles and also diverse substrate polar angles. Our prepared samples, after remove masks, show large area touching triangular pattern with different inter particle distances in greater polar angles. To get more sense about optical response of the samples such as transmittance and also electric field distribution, we use finite difference time domain method in simulation part. The transmittance plot shows one narrow or multi-channel adjustable deep depend on inter-particle distances which can be controlled by azimuthally angle in nano lithography process. Also, due to the isoelliptical points in the transmittance spectra; we can see the bright and dark plasmon modes coupling and thus the Fano like resonance takes place in the optical spectral region which is very useful for refractive index measurement.

Cavity mode enhancement of terahertz emission from equilateral triangular microstrip antennas of the high-T c superconductor Bi2Sr2CaCu2O8 + δ.

PubMed

Cerkoney, Daniel P; Reid, Candy; Doty, Constance M; Gramajo, Ashley; Campbell, Tyler D; Morales, Manuel A; Delfanazari, Kaveh; Tsujimoto, Manabu; Kashiwagi, Takanari; Yamamoto, Takashi; Watanabe, Chiharu; Minami, Hidetoshi; Kadowaki, Kazuo; Klemm, Richard A

2017-01-11

We study the transverse magnetic (TM) electromagnetic cavity mode wave functions for an ideal equilateral triangular microstrip antenna (MSA) exhibiting C 3v point group symmetry. When the C 3v operations are imposed upon the antenna, the TM(m,n) modes with wave vectors [Formula: see text] are much less dense than commonly thought. The R 3 operations restrict the integral n and m to satisfy [Formula: see text], where [Formula: see text] and [Formula: see text] for the modes even and odd under reflections about the three mirror planes, respectively. We calculate the forms of representative wave functions and the angular dependence of the output power when these modes are excited by the uniform and non-uniform ac Josephson current sources in thin, ideally equilateral triangular MSAs employing the intrinsic Josephson junctions in the high transition temperature T c superconductor Bi 2 Sr 2 CaCu 2 [Formula: see text], and fit the emissions data from an earlier sample for which the C 3v symmetry was apparently broken.

Space station architectural elements model study

NASA Technical Reports Server (NTRS)

Taylor, T. C.; Spencer, J. S.; Rocha, C. J.; Kahn, E.; Cliffton, E.; Carr, C.

1987-01-01

The worksphere, a user controlled computer workstation enclosure, was expanded in scope to an engineering workstation suitable for use on the Space Station as a crewmember desk in orbit. The concept was also explored as a module control station capable of enclosing enough equipment to control the station from each module. The concept has commercial potential for the Space Station and surface workstation applications. The central triangular beam interior configuration was expanded and refined to seven different beam configurations. These included triangular on center, triangular off center, square, hexagonal small, hexagonal medium, hexagonal large and the H beam. Each was explored with some considerations as to the utilities and a suggested evaluation factor methodology was presented. Scale models of each concept were made. The models were helpful in researching the seven beam configurations and determining the negative residual (unused) volume of each configuration. A flexible hardware evaluation factor concept is proposed which could be helpful in evaluating interior space volumes from a human factors point of view. A magnetic version with all the graphics is available from the author or the technical monitor.

Balanced Central Schemes for the Shallow Water Equations on Unstructured Grids

NASA Technical Reports Server (NTRS)

Bryson, Steve; Levy, Doron

2004-01-01

We present a two-dimensional, well-balanced, central-upwind scheme for approximating solutions of the shallow water equations in the presence of a stationary bottom topography on triangular meshes. Our starting point is the recent central scheme of Kurganov and Petrova (KP) for approximating solutions of conservation laws on triangular meshes. In order to extend this scheme from systems of conservation laws to systems of balance laws one has to find an appropriate discretization of the source terms. We first show that for general triangulations there is no discretization of the source terms that corresponds to a well-balanced form of the KP scheme. We then derive a new variant of a central scheme that can be balanced on triangular meshes. We note in passing that it is straightforward to extend the KP scheme to general unstructured conformal meshes. This extension allows us to recover our previous well-balanced scheme on Cartesian grids. We conclude with several simulations, verifying the second-order accuracy of our scheme as well as its well-balanced properties.

TIME-DEPENDENT COROTATION RESONANCE IN BARRED GALAXIES

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

Wu, Yu-Ting; Taam, Ronald E.; Pfenniger, Daniel, E-mail: ytwu@asiaa.sinica.edu.tw, E-mail: daniel.pfenniger@unige.ch, E-mail: taam@asiaa.sinica.edu.tw

2016-10-20

The effective potential neighboring the corotation resonance region in barred galaxies is shown to be strongly time-dependent in any rotating frame, due to the competition of nearby perturbations of similar strengths with differing rotation speeds. Contrary to the generally adopted assumption that in the bar rotating frame the corotation region should possess four stationary equilibrium points (Lagrange points), with high quality N -body simulations, we localize the instantaneous equilibrium points (EPs) and find that they circulate or oscillate broadly in azimuth with respect to the pattern speeds of the inner or outer perturbations. This implies that at the particle levelmore » the Jacobi integral is not well conserved around the corotation radius. That is, angular momentum exchanges decouple from energy exchanges, enhancing the chaotic diffusion of stars through the corotation region.« less

Cause and Cure - Deterioration in Accuracy of CFD Simulations With Use of High-Aspect-Ratio Triangular Tetrahedral Grids

NASA Technical Reports Server (NTRS)

Chang, Sin-Chung; Chang, Chau-Lyan; Venkatachari, Balaji Shankar

2017-01-01

Traditionally high-aspect ratio triangular/tetrahedral meshes are avoided by CFD re-searchers in the vicinity of a solid wall, as it is known to reduce the accuracy of gradient computations in those regions and also cause numerical instability. Although for certain complex geometries, the use of high-aspect ratio triangular/tetrahedral elements in the vicinity of a solid wall can be replaced by quadrilateral/prismatic elements, ability to use triangular/tetrahedral elements in such regions without any degradation in accuracy can be beneficial from a mesh generation point of view. The benefits also carry over to numerical frameworks such as the space-time conservation element and solution element (CESE), where triangular/tetrahedral elements are the mandatory building blocks. With the requirement of the CESE method in mind, a rigorous mathematical framework that clearly identities the reason behind the difficulties in use of such high-aspect ratio triangular/tetrahedral elements is presented here. As will be shown, it turns out that the degree of accuracy deterioration of gradient computation involving a triangular element is hinged on the value of its shape factor Gamma def = sq sin Alpha1 + sq sin Alpha2 + sq sin Alpha3, where Alpha1; Alpha2 and Alpha3 are the internal angles of the element. In fact, it is shown that the degree of accuracy deterioration increases monotonically as the value of Gamma decreases monotonically from its maximal value 9/4 (attained by an equilateral triangle only) to a value much less than 1 (associated with a highly obtuse triangle). By taking advantage of the fact that a high-aspect ratio triangle is not necessarily highly obtuse, and in fact it can have a shape factor whose value is close to the maximal value 9/4, a potential solution to avoid accuracy deterioration of gradient computation associated with a high-aspect ratio triangular grid is given. Also a brief discussion on the extension of the current mathematical framework to the tetrahedral-grid case along with some of the practical results of this extension is also provided. Furthermore, through the use of numerical simulations of practical viscous problems involving high-Reynolds number flows, the effectiveness of the gradient evaluation procedures within the CESE framework (that have their basis on the analysis presented here) to produce accurate and stable results on such high-aspect ratio meshes is also showcased.

Influence of a weak gravitational wave on a bound system of two point-masses. [of binary stars

NASA Technical Reports Server (NTRS)

Turner, M. S.

1979-01-01

The problem of a weak gravitational wave impinging upon a nonrelativistic bound system of two point masses is considered. The geodesic equation for each mass is expanded in terms of two small parameters, v/c and dimensionless wave amplitude, in a manner similar to the post-Newtonian expansion; the geodesic equations are resolved into orbital and center-of-mass equations of motion. The effect of the wave on the orbit is determined by using Lagrange's planetary equations to calculate the time evolution of the orbital elements. The gauge properties of the solutions and, in particular, the gauge invariance of the secular effects are discussed.

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

Lu, Yuan; Zuo, Xu, E-mail: xzuo@nankai.edu.cn; Feng, Min

Motivated by recent theoretical predications for Dirac cone in two-dimensional (2D) triangular lattice [H. Ishizuka, Phys. Rev. Lett. 109, 237207 (2012)], first-principles studies are performed to predict Dirac cones in artificial structures of 3d transitional-metals (TM = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) doped Mg-Al spinels. In investigated artificial structures, TM dopants substitute specific positions of the B sub-lattice in Mg-Al spinel, and form a quasi-2D triangular lattice in the a-b plane. Calculated results illustrate the existence of the spin-polarized Dirac cones formed in d-wave bands at (around) the K-point in the momentum space. The study provides a promisingmore » route for engineering Dirac physics in condensed matters.« less

Centrifuge Rotor Models: A Comparison of the Euler-Lagrange and the Bond Graph Modeling Approach

NASA Technical Reports Server (NTRS)

Granda, Jose J.; Ramakrishnan, Jayant; Nguyen, Louis H.

2006-01-01

A viewgraph presentation on centrifuge rotor models with a comparison using Euler-Lagrange and bond graph methods is shown. The topics include: 1) Objectives; 2) MOdeling Approach Comparisons; 3) Model Structures; and 4) Application.

On the commutator of C^{\\infty}} -symmetries and the reduction of Euler-Lagrange equations

NASA Astrophysics Data System (ADS)

Ruiz, A.; Muriel, C.; Olver, P. J.

2018-04-01

A novel procedure to reduce by four the order of Euler-Lagrange equations associated to nth order variational problems involving single variable integrals is presented. In preparation, a new formula for the commutator of two \

Dirac structures in vakonomic mechanics

NASA Astrophysics Data System (ADS)

Jiménez, Fernando; Yoshimura, Hiroaki

2015-08-01

In this paper, we explore dynamics of the nonholonomic system called vakonomic mechanics in the context of Lagrange-Dirac dynamical systems using a Dirac structure and its associated Hamilton-Pontryagin variational principle. We first show the link between vakonomic mechanics and nonholonomic mechanics from the viewpoints of Dirac structures as well as Lagrangian submanifolds. Namely, we clarify that Lagrangian submanifold theory cannot represent nonholonomic mechanics properly, but vakonomic mechanics instead. Second, in order to represent vakonomic mechanics, we employ the space TQ ×V∗, where a vakonomic Lagrangian is defined from a given Lagrangian (possibly degenerate) subject to nonholonomic constraints. Then, we show how implicit vakonomic Euler-Lagrange equations can be formulated by the Hamilton-Pontryagin variational principle for the vakonomic Lagrangian on the extended Pontryagin bundle (TQ ⊕T∗ Q) ×V∗. Associated with this variational principle, we establish a Dirac structure on (TQ ⊕T∗ Q) ×V∗ in order to define an intrinsic vakonomic Lagrange-Dirac system. Furthermore, we also establish another construction for the vakonomic Lagrange-Dirac system using a Dirac structure on T∗ Q ×V∗, where we introduce a vakonomic Dirac differential. Finally, we illustrate our theory of vakonomic Lagrange-Dirac systems by some examples such as the vakonomic skate and the vertical rolling coin.

Variational Ridging in Sea Ice Models

NASA Astrophysics Data System (ADS)

Roberts, A.; Hunke, E. C.; Lipscomb, W. H.; Maslowski, W.; Kamal, S.

2017-12-01

This work presents the results of a new development to make basin-scale sea ice models aware of the shape, porosity and extent of individual ridges within the pack. We have derived an analytic solution for the Euler-Lagrange equation of individual ridges that accounts for non-conservative forces, and therefore the compressive strength of individual ridges. Because a region of the pack is simply a collection of paths of individual ridges, we are able to solve the Euler-Lagrange equation for a large-scale sea ice field also, and therefore the compressive strength of a region of the pack that explicitly accounts for the macro-porosity of ridged debris. We make a number of assumptions that have simplified the problem, such as treating sea ice as a granular material in ridges, and assuming that bending moments associated with ridging are perturbations around an isostatic state. Regardless of these simplifications, the ridge model is remarkably predictive of macro-porosity and ridge shape, and, because our equations are analytic, they do not require costly computations to solve the Euler-Lagrange equation of ridges on the large scale. The new ridge model is therefore applicable to large-scale sea ice models. We present results from this theoretical development, as well as plans to apply it to the Regional Arctic System Model and a community sea ice code. Most importantly, the new ridging model is particularly useful for pinpointing gaps in our observational record of sea ice ridges, and points to the need for improved measurements of the evolution of porosity of deformed ice in the Arctic and Antarctic. Such knowledge is not only useful for improving models, but also for improving estimates of sea ice volume derived from altimetric measurements of sea ice freeboard.

A composite experimental dynamic substructuring method based on partitioned algorithms and localized Lagrange multipliers

NASA Astrophysics Data System (ADS)

Abbiati, Giuseppe; La Salandra, Vincenzo; Bursi, Oreste S.; Caracoglia, Luca

2018-02-01

Successful online hybrid (numerical/physical) dynamic substructuring simulations have shown their potential in enabling realistic dynamic analysis of almost any type of non-linear structural system (e.g., an as-built/isolated viaduct, a petrochemical piping system subjected to non-stationary seismic loading, etc.). Moreover, owing to faster and more accurate testing equipment, a number of different offline experimental substructuring methods, operating both in time (e.g. the impulse-based substructuring) and frequency domains (i.e. the Lagrange multiplier frequency-based substructuring), have been employed in mechanical engineering to examine dynamic substructure coupling. Numerous studies have dealt with the above-mentioned methods and with consequent uncertainty propagation issues, either associated with experimental errors or modelling assumptions. Nonetheless, a limited number of publications have systematically cross-examined the performance of the various Experimental Dynamic Substructuring (EDS) methods and the possibility of their exploitation in a complementary way to expedite a hybrid experiment/numerical simulation. From this perspective, this paper performs a comparative uncertainty propagation analysis of three EDS algorithms for coupling physical and numerical subdomains with a dual assembly approach based on localized Lagrange multipliers. The main results and comparisons are based on a series of Monte Carlo simulations carried out on a five-DoF linear/non-linear chain-like systems that include typical aleatoric uncertainties emerging from measurement errors and excitation loads. In addition, we propose a new Composite-EDS (C-EDS) method to fuse both online and offline algorithms into a unique simulator. Capitalizing from the results of a more complex case study composed of a coupled isolated tank-piping system, we provide a feasible way to employ the C-EDS method when nonlinearities and multi-point constraints are present in the emulated system.

78 FR 43821 - Final Flood Elevation Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-22

............ +902 Unincorporated Areas of LaGrange County. Big Long Lake Entire shoreline......... +957 Unincorporated Areas of LaGrange County. Big Turkey Lake Entire shoreline within +932 Unincorporated Areas of... Vertical Datum. + North American Vertical Datum. Depth in feet above ground. [caret] Mean Sea Level...

Quantitative Tomography for Continuous Variable Quantum Systems

NASA Astrophysics Data System (ADS)

Landon-Cardinal, Olivier; Govia, Luke C. G.; Clerk, Aashish A.

2018-03-01

We present a continuous variable tomography scheme that reconstructs the Husimi Q function (Wigner function) by Lagrange interpolation, using measurements of the Q function (Wigner function) at the Padua points, conjectured to be optimal sampling points for two dimensional reconstruction. Our approach drastically reduces the number of measurements required compared to using equidistant points on a regular grid, although reanalysis of such experiments is possible. The reconstruction algorithm produces a reconstructed function with exponentially decreasing error and quasilinear runtime in the number of Padua points. Moreover, using the interpolating polynomial of the Q function, we present a technique to directly estimate the density matrix elements of the continuous variable state, with only a linear propagation of input measurement error. Furthermore, we derive a state-independent analytical bound on this error, such that our estimate of the density matrix is accompanied by a measure of its uncertainty.

Using Solar Radiation Pressure to Control L2 Orbits

NASA Technical Reports Server (NTRS)

Tene, Noam; Richon, Karen; Folta, David

1998-01-01

The main perturbations at the Sun-Earth Lagrange points L1 and L2 are from solar radiation pressure (SRP), the Moon and the planets. Traditional approaches to trajectory design for Lagrange-point orbits use maneuvers every few months to correct for these perturbations. The gravitational effects of the Moon and the planets are small and periodic. However, they cannot be neglected because small perturbations in the direction of the unstable eigenvector are enough to cause exponential growth within a few months. The main effect of a constant SRP is to shift the center of the orbit by a small distance. For spacecraft with large sun-shields like the Microwave Anisotropy Probe (MAP) and the Next Generation Space Telescope (NGST), the SRP effect is larger than all other perturbations and depends mostly on spacecraft attitude. Small variations in the spacecraft attitude are large enough to excite or control the exponential eigenvector. A closed-loop linear controller based on the SRP variations would eliminate one of the largest errors to the orbit and provide a continuous acceleration for use in controlling other disturbances. It is possible to design reference trajectories that account for the periodic lunar and planetary perturbations and still satisfy mission requirements. When such trajectories are used the acceleration required to control the unstable eigenvector is well within the capabilities of a continuous linear controller. Initial estimates show that by using attitude control it should be possible to minimize and even eliminate thruster maneuvers for station keeping.

Simple, Robust Cryogenic Propellant Depot for Near Term Applications

NASA Technical Reports Server (NTRS)

McLean, Christopher; Pitchford, Brian; Mustafi, Shuvo; Wollen, Mark; Walls, Laurie; Schmidt, Jeff

2011-01-01

The ability to refuel cryogenic propulsion stages on-orbit provides an innovative paradigm shift for space transportation supporting National Aeronautics and Space Administration s (NASA) Exploration program as well as deep space robotic, national security and commercial missions. Refueling enables large beyond low Earth orbit (LEO) missions without requiring super heavy lift vehicles that must continuously grow to support increasing mission demands as America s exploration transitions from early Lagrange point missions to near Earth objects (NEO), the lunar surface and eventually Mars. Earth-to-orbit launch can be optimized to provide competitive, cost-effective solutions that allow sustained exploration. This paper describes an experimental platform developed to demonstrate the major technologies required for fuel depot technology. This test bed is capable of transferring residual liquid hydrogen (LH2) or liquid oxygen (LO2) from a Centaur upper stage, and storage in a secondary tank for up to one year on-orbit. A dedicated, flight heritage spacecraft bus is attached to an Evolved Expendable Launch Vehicle (EELV) Secondary Payload Adapter (ESPA) ring supporting experiments and data collection. This platform can be deployed as early as Q1 2013. The propellant depot design described in this paper can be deployed affordably this decade supporting missions to Earth-Moon Lagrange points and lunar fly by. The same depot concept can be scaled up to support more demanding missions and launch capabilities. The enabling depot design features, technologies and concept of operations are described.

Initial Results of a Survey of Earth's L4 Point for Possible Earth Trojan Asteroids

NASA Astrophysics Data System (ADS)

Connors, M.; Veillet, C.; Wiegert, P.; Innanen, K.; Mikkola, S.

2000-10-01

Using the Canada-France-Hawaii 3.6 m telescope and the new CFH12k wide-field CCD imager, a survey of the region near Earth's L4 (morning) Lagrange Point was conducted in May and July/August 2000, in hopes of finding asteroids at or near this point. This survey was motivated by the dynamical interest of a possible Earth Trojan asteroid (ETA) population and by the fact that they would be the easiest asteroids to access from Earth. Recent calculations (Wiegert, Innanen and Mikkola, 2000, Icarus v. 145, 33-43) indicate stability of objects in ETA orbits over a million year timescale and that their on-sky density would be greatest roughly five degrees sunward of the L4 position. An optimized search technique was used, with tracking at the anticipated rate of the target bodies, near real-time scanning of images, and duplication of fields to aid in detection and permit followup. Limited time is available on any given night to search near the Lagrange points, and operations must be conducted at large air mass. Approximately 9 square degrees were efficiently searched and two interesting asteroids were found, NEA 2000 PM8 and our provisionally named CFZ001. CFZ001 cannot be excluded from being an Earth Trojan although that is not the optimal solution for the short arc we observed. This object, of R magnitude 22, was easily detected, suggesting that our search technique worked well. This survey supports the earlier conclusion of Whitely and Tholen (1998, Icarus v. 136, 154-167) that a large population of several hundred meter diameter ETAs does not exist. However, our effective search technique and the discovery of two interesting asteroids suggest the value of completing the survey with approximately 10 more square degrees to be searched near L4 and a comparable search to be done at L5. Funding from Canada's NSERC and HIA and the Academic Research Fund of Athabasca University is gratefully acknowledged.

Efficient computer algebra algorithms for polynomial matrices in control design

NASA Technical Reports Server (NTRS)

Baras, J. S.; Macenany, D. C.; Munach, R.

1989-01-01

The theory of polynomial matrices plays a key role in the design and analysis of multi-input multi-output control and communications systems using frequency domain methods. Examples include coprime factorizations of transfer functions, cannonical realizations from matrix fraction descriptions, and the transfer function design of feedback compensators. Typically, such problems abstract in a natural way to the need to solve systems of Diophantine equations or systems of linear equations over polynomials. These and other problems involving polynomial matrices can in turn be reduced to polynomial matrix triangularization procedures, a result which is not surprising given the importance of matrix triangularization techniques in numerical linear algebra. Matrices with entries from a field and Gaussian elimination play a fundamental role in understanding the triangularization process. In the case of polynomial matrices, matrices with entries from a ring for which Gaussian elimination is not defined and triangularization is accomplished by what is quite properly called Euclidean elimination. Unfortunately, the numerical stability and sensitivity issues which accompany floating point approaches to Euclidean elimination are not very well understood. New algorithms are presented which circumvent entirely such numerical issues through the use of exact, symbolic methods in computer algebra. The use of such error-free algorithms guarantees that the results are accurate to within the precision of the model data--the best that can be hoped for. Care must be taken in the design of such algorithms due to the phenomenon of intermediate expressions swell.

Cultural Resources Inventory of Lands Adjacent to Big Sandy Lake. Volume 1,

DTIC Science & Technology

1979-01-18

population density. Late Prehistoric: 300 - 1640 A.D. Intensive wild rice -bison economic systems; St. Croix, Kathio, Clam River, Balckduck and Sandy...type are located on W- streams and near lake outlets that tend to be good wild rice harvesting .1. areas. Projectile points are either ososceles...triangular br side-notched points. The subsistence pattern of these people is that of hunting deer and smaller mammals and wild rice gathering. The time

Discovering phases, phase transitions, and crossovers through unsupervised machine learning: A critical examination

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

Hu, Wenjian; Singh, Rajiv R. P.; Scalettar, Richard T.

Here, we apply unsupervised machine learning techniques, mainly principal component analysis (PCA), to compare and contrast the phase behavior and phase transitions in several classical spin models - the square and triangular-lattice Ising models, the Blume-Capel model, a highly degenerate biquadratic-exchange spin-one Ising (BSI) model, and the 2D XY model, and examine critically what machine learning is teaching us. We find that quantified principal components from PCA not only allow exploration of different phases and symmetry-breaking, but can distinguish phase transition types and locate critical points. We show that the corresponding weight vectors have a clear physical interpretation, which ismore » particularly interesting in the frustrated models such as the triangular antiferromagnet, where they can point to incipient orders. Unlike the other well-studied models, the properties of the BSI model are less well known. Using both PCA and conventional Monte Carlo analysis, we demonstrate that the BSI model shows an absence of phase transition and macroscopic ground-state degeneracy. The failure to capture the 'charge' correlations (vorticity) in the BSI model (XY model) from raw spin configurations points to some of the limitations of PCA. Finally, we employ a nonlinear unsupervised machine learning procedure, the 'antoencoder method', and demonstrate that it too can be trained to capture phase transitions and critical points.« less

Discovering phases, phase transitions, and crossovers through unsupervised machine learning: A critical examination

DOE PAGES

Hu, Wenjian; Singh, Rajiv R. P.; Scalettar, Richard T.

2017-06-19

Here, we apply unsupervised machine learning techniques, mainly principal component analysis (PCA), to compare and contrast the phase behavior and phase transitions in several classical spin models - the square and triangular-lattice Ising models, the Blume-Capel model, a highly degenerate biquadratic-exchange spin-one Ising (BSI) model, and the 2D XY model, and examine critically what machine learning is teaching us. We find that quantified principal components from PCA not only allow exploration of different phases and symmetry-breaking, but can distinguish phase transition types and locate critical points. We show that the corresponding weight vectors have a clear physical interpretation, which ismore » particularly interesting in the frustrated models such as the triangular antiferromagnet, where they can point to incipient orders. Unlike the other well-studied models, the properties of the BSI model are less well known. Using both PCA and conventional Monte Carlo analysis, we demonstrate that the BSI model shows an absence of phase transition and macroscopic ground-state degeneracy. The failure to capture the 'charge' correlations (vorticity) in the BSI model (XY model) from raw spin configurations points to some of the limitations of PCA. Finally, we employ a nonlinear unsupervised machine learning procedure, the 'antoencoder method', and demonstrate that it too can be trained to capture phase transitions and critical points.« less

Discovering phases, phase transitions, and crossovers through unsupervised machine learning: A critical examination

NASA Astrophysics Data System (ADS)

Hu, Wenjian; Singh, Rajiv R. P.; Scalettar, Richard T.

2017-06-01

We apply unsupervised machine learning techniques, mainly principal component analysis (PCA), to compare and contrast the phase behavior and phase transitions in several classical spin models—the square- and triangular-lattice Ising models, the Blume-Capel model, a highly degenerate biquadratic-exchange spin-1 Ising (BSI) model, and the two-dimensional X Y model—and we examine critically what machine learning is teaching us. We find that quantified principal components from PCA not only allow the exploration of different phases and symmetry-breaking, but they can distinguish phase-transition types and locate critical points. We show that the corresponding weight vectors have a clear physical interpretation, which is particularly interesting in the frustrated models such as the triangular antiferromagnet, where they can point to incipient orders. Unlike the other well-studied models, the properties of the BSI model are less well known. Using both PCA and conventional Monte Carlo analysis, we demonstrate that the BSI model shows an absence of phase transition and macroscopic ground-state degeneracy. The failure to capture the "charge" correlations (vorticity) in the BSI model (X Y model) from raw spin configurations points to some of the limitations of PCA. Finally, we employ a nonlinear unsupervised machine learning procedure, the "autoencoder method," and we demonstrate that it too can be trained to capture phase transitions and critical points.

Deconfined quantum critical point on the triangular lattice

NASA Astrophysics Data System (ADS)

Jian, Chao-Ming; Thomson, Alex; Rasmussen, Alex; Bi, Zhen; Xu, Cenke

2018-05-01

In this work we propose a theory for the deconfined quantum critical point (DQCP) for spin-1/2 systems on a triangular lattice, which is a direct unfine-tuned quantum phase transition between the standard "√{3 }×√{3 } " noncollinear antiferromagnetic order (or the so-called 120∘ state) and the "√{12 }×√{12 } " valence solid bond (VBS) order, both of which are very standard ordered phases often observed in numerical simulations. This transition is beyond the standard Landau-Ginzburg paradigm and is also fundamentally different from the original DQCP theory on the square lattice due to the very different structures of both the magnetic and VBS order on frustrated lattices. We first propose a topological term in the effective-field theory that captures the "intertwinement" between the √{3 }×√{3 } antiferromagnetic order and the √{12 }×√{12 } VBS order. Then using a controlled renormalization-group calculation, we demonstrate that an unfine-tuned direct continuous DQCP exists between the two ordered phases mentioned above. This DQCP is described by the Nf=4 quantum electrodynamics (QED) with an emergent PSU(4)=SU(4)/Z4 symmetry only at the critical point. The aforementioned topological term is also naturally derived from the Nf=4 QED. We also point out that physics around this DQCP is analogous to the boundary of a 3 d bosonic symmetry- protected topological state with only on-site symmetries.

An immersed boundary method for simulating vesicle dynamics in three dimensions

NASA Astrophysics Data System (ADS)

Seol, Yunchang; Hu, Wei-Fan; Kim, Yongsam; Lai, Ming-Chih

2016-10-01

We extend our previous immersed boundary (IB) method for 3D axisymmetric inextensible vesicle in Navier-Stokes flows (Hu et al., 2014 [17]) to general three dimensions. Despite a similar spirit in numerical algorithms to the axisymmetric case, the fully 3D numerical implementation is much more complicated and is far from straightforward. A vesicle membrane surface is known to be incompressible and exhibits bending resistance. As in 3D axisymmetric case, instead of keeping the vesicle locally incompressible, we adopt a modified elastic tension energy to make the vesicle surface patch nearly incompressible so that solving the unknown tension (Lagrange multiplier for the incompressible constraint) can be avoided. Nevertheless, the new elastic force derived from the modified tension energy has exactly the same mathematical form as the original one except the different definitions of tension. The vesicle surface is discretized on a triangular mesh where the elastic tension and bending force are calculated on each vertex (Lagrangian marker in the IB method) of the triangulation. A series of numerical tests on the present scheme are conducted to illustrate the robustness and applicability of the method. We perform the convergence study for the immersed boundary forces and the fluid velocity field. We then study the vesicle dynamics in various flows such as quiescent, simple shear, and gravitational flows. Our numerical results show good agreements with those obtained in previous theoretical, experimental and numerical studies.

Integrable Seven-Point Discrete Equations and Second-Order Evolution Chains

NASA Astrophysics Data System (ADS)

Adler, V. E.

2018-04-01

We consider differential-difference equations defining continuous symmetries for discrete equations on a triangular lattice. We show that a certain combination of continuous flows can be represented as a secondorder scalar evolution chain. We illustrate the general construction with a set of examples including an analogue of the elliptic Yamilov chain.

Higher-order triangular spectral element method with optimized cubature points for seismic wavefield modeling

NASA Astrophysics Data System (ADS)

Liu, Youshan; Teng, Jiwen; Xu, Tao; Badal, José

2017-05-01

The mass-lumped method avoids the cost of inverting the mass matrix and simultaneously maintains spatial accuracy by adopting additional interior integration points, known as cubature points. To date, such points are only known analytically in tensor domains, such as quadrilateral or hexahedral elements. Thus, the diagonal-mass-matrix spectral element method (SEM) in non-tensor domains always relies on numerically computed interpolation points or quadrature points. However, only the cubature points for degrees 1 to 6 are known, which is the reason that we have developed a p-norm-based optimization algorithm to obtain higher-order cubature points. In this way, we obtain and tabulate new cubature points with all positive integration weights for degrees 7 to 9. The dispersion analysis illustrates that the dispersion relation determined from the new optimized cubature points is comparable to that of the mass and stiffness matrices obtained by exact integration. Simultaneously, the Lebesgue constant for the new optimized cubature points indicates its surprisingly good interpolation properties. As a result, such points provide both good interpolation properties and integration accuracy. The Courant-Friedrichs-Lewy (CFL) numbers are tabulated for the conventional Fekete-based triangular spectral element (TSEM), the TSEM with exact integration, and the optimized cubature-based TSEM (OTSEM). A complementary study demonstrates the spectral convergence of the OTSEM. A numerical example conducted on a half-space model demonstrates that the OTSEM improves the accuracy by approximately one order of magnitude compared to the conventional Fekete-based TSEM. In particular, the accuracy of the 7th-order OTSEM is even higher than that of the 14th-order Fekete-based TSEM. Furthermore, the OTSEM produces a result that can compete in accuracy with the quadrilateral SEM (QSEM). The high accuracy of the OTSEM is also tested with a non-flat topography model. In terms of computational efficiency, the OTSEM is more efficient than the Fekete-based TSEM, although it is slightly costlier than the QSEM when a comparable numerical accuracy is required.

Phase diagram of the triangular-lattice Potts antiferromagnet

DOE PAGES

Jacobsen, Jesper Lykke; Salas, Jesus; Scullard, Christian R.

2017-07-28

Here, we study the phase diagram of the triangular-lattice Q-state Potts model in the realmore » $(Q, v)$ -plane, where $$v={\\rm e}^J-1$$ is the temperature variable. Our first goal is to provide an obviously missing feature of this diagram: the position of the antiferromagnetic critical curve. This curve turns out to possess a bifurcation point with two branches emerging from it, entailing important consequences for the global phase diagram. We have obtained accurate numerical estimates for the position of this curve by combining the transfer-matrix approach for strip graphs with toroidal boundary conditions and the recent method of critical polynomials. The second goal of this work is to study the corresponding $$A_{p-1}$$ RSOS model on the torus, for integer $$p=4, 5, \\ldots, 8$$ . We clarify its relation to the corresponding Potts model, in particular concerning the role of boundary conditions. For certain values of p, we identify several new critical points and regimes for the RSOS model and we initiate the study of the flows between the corresponding field theories.« less

Conventional wallboard with latent heat storage for passive solar applications

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

Kedl, R.J.

1990-01-01

Conventional wallboard impregnated with octadecane paraffin (Melting Point -- 73.5{degree}F) is being developed as a building material with latent heat storage for passive solar applications. Impregnation was accomplished simply by soaking the wallboard in molten paraffin. Concentrations of paraffin in the combined product as high as 35{percent} by weight were achieved. In support of this concept, a computer model was developed to describe thermal transport and storage by a phase change material (PCM) dispersed in a porous media. The computer model was confirmed by comparison with known analytical solutions where the PCM melts at a specific melting point. However, agreementmore » between the model and an experimentally produced thermal transient involving impregnated wallboard was only good after the model was modified to allow the paraffin to melt over a temperature range. This was accomplished by replacing the heat of fusion with a triangular heat capacity relationship that mimics the triangular melt curve found through differential scanning calorimetry. When this change was made, agreement between the model and the experimental transient was very good. 4 refs., 8 figs.« less

Conventional wallboard with latent heat storage for passive solar applications

NASA Astrophysics Data System (ADS)

Kedl, R. J.

Conventional wallboard impregnated with octadecane paraffin (melting point -- 73.5 F) is being developed as a building material with latent heat storage for passive solar applications. Impregnation was accomplished simply by soaking the wallboard in molten paraffin. Concentrations of paraffin in the combined product as high as 35 percent by weight were achieved. In support of this concept, a computer model was developed to describe thermal transport and storage by a phase change material (PCM) dispersed in a porous media. The computer model was confirmed by comparison with known analytical solutions where the PCM melts at a specific melting point. However, agreement between the model and an experimentally produced thermal transient involving impregnated wallboard was only good after the model was modified to allow the paraffin to melt over a temperature range. This was accomplished by replacing the heat of fusion with a triangular heat capacity relationship that mimics the triangular melt curve found through differential scanning calorimetry. When this change was made, agreement between the model and the experimental transient was very good.

Contact solution algorithms

NASA Technical Reports Server (NTRS)

Tielking, John T.

1989-01-01

Two algorithms for obtaining static contact solutions are described in this presentation. Although they were derived for contact problems involving specific structures (a tire and a solid rubber cylinder), they are sufficiently general to be applied to other shell-of-revolution and solid-body contact problems. The shell-of-revolution contact algorithm is a method of obtaining a point load influence coefficient matrix for the portion of shell surface that is expected to carry a contact load. If the shell is sufficiently linear with respect to contact loading, a single influence coefficient matrix can be used to obtain a good approximation of the contact pressure distribution. Otherwise, the matrix will be updated to reflect nonlinear load-deflection behavior. The solid-body contact algorithm utilizes a Lagrange multiplier to include the contact constraint in a potential energy functional. The solution is found by applying the principle of minimum potential energy. The Lagrange multiplier is identified as the contact load resultant for a specific deflection. At present, only frictionless contact solutions have been obtained with these algorithms. A sliding tread element has been developed to calculate friction shear force in the contact region of the rolling shell-of-revolution tire model.

Dirac cones in artificial structures of 3d transitional-metals doped Mg-Al spinels

NASA Astrophysics Data System (ADS)

Lu, Yuan; Feng, Min; Shao, Bin; Zuo, Xu

2014-05-01

Motivated by recent theoretical predications for Dirac cone in two-dimensional (2D) triangular lattice [H. Ishizuka, Phys. Rev. Lett. 109, 237207 (2012)], first-principles studies are performed to predict Dirac cones in artificial structures of 3d transitional-metals (TM = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) doped Mg-Al spinels. In investigated artificial structures, TM dopants substitute specific positions of the B sub-lattice in Mg-Al spinel, and form a quasi-2D triangular lattice in the a-b plane. Calculated results illustrate the existence of the spin-polarized Dirac cones formed in d-wave bands at (around) the K-point in the momentum space. The study provides a promising route for engineering Dirac physics in condensed matters.

Comparative Analysis of Membership Function on Mamdani Fuzzy Inference System for Decision Making

NASA Astrophysics Data System (ADS)

harliana, Putri; Rahim, Robbi

2017-12-01

Membership function is a curve that shows mapping the input data points into the value or degree of membership which has an interval between 0 and 1. One way to get membership value is through a function approach. There are some membership functions can be used on mamdani fuzzy inference system. They are triangular, trapezoid, singleton, sigmoid, Gaussian, etc. In this paper only discuss three membership functions, are triangular, trapezoid and Gaussian. These three membership functions will be compared to see the difference in parameter values and results obtained. For case study in this paper is admission of students at popular school. There are three variable can be used, they are students’ report, IQ score and parents’ income. Which will then be created if-then rules.

Investigations at supersonic speeds of 22 triangular wings representing two airfoil sections for each of 11 apex angles

NASA Technical Reports Server (NTRS)

Love, Eugene S

1949-01-01

Data obtained from wind tunnel investigations of two series of 11 triangular wings conducted at Mach numbers of 1.62, 1.92, and 1.40 to determine the effect of leading-edge shape and to compare actual test values with the nonviscous linear theory are presented. The two series of wings had identical plan forms, a constant thickness ratio of 8 percent, a constant location of maximum-thickness point of 18 percent, and a range of apex half-angles from 10 degrees to forty-five degrees. The first series has an elliptical leading edge and the second series a wedge leading edge. Measurements were made of lift, drag, pitching moment, and pressure distribution, the latter being confined to three wings at one Mach number.

An Unstable Arch Model of a Solar Flare

DTIC Science & Technology

1976-08-10

where the Euler-Lagrange equation becomes singular. We now expand f(r) and g(r) around the singular point r. Thus k JA + - p x, (3.20) m where x...current layer, etc.) can result only from convection. The equations we will use are ()B E 2 - VX(vXB)- _ VX(1TV XB), (4.8) E+ vX B=77j (4.9) C and curl (P...d- curl (J ( curl B) X B+pg . (4.10) Since the treatment is principally concerned with resistive instabilities whose growth times are long compared to

Overview: Solar Electric Propulsion Concept Designs for SEP Technology Demonstration Mission

NASA Technical Reports Server (NTRS)

Mcguire, Melissa L.; Hack, Kurt J.; Manzella, David; Herman, Daniel

2014-01-01

JPC presentation of the Concept designs for NASA Solar Electric Propulsion Technology Demonstration mission paper. Multiple Solar Electric Propulsion Technology Demonstration Missions were developed to assess vehicle performance and estimated mission cost. Concepts ranged from a 10,000 kg spacecraft capable of delivering 4000 kg of payload to one of the Earth Moon Lagrange points in support of future human-crewed outposts to a 180 kg spacecraft capable of performing an asteroid rendezvous mission after launched to a geostationary transfer orbit as a secondary payload.

The Next Generation Space Telescope

NASA Technical Reports Server (NTRS)

Mather, John C.; Seery, Bernard (Technical Monitor)

2001-01-01

The Next Generation Space Telescope NGST is an 6-7 m class radiatively cooled telescope, planned for launch to the Lagrange point L2 in 2009, to be built by a partnership of NASA, ESA, and CSA. The NGST science program calls for three core instruments: 1) Near IR camera, 0.6 - 5 micrometer; 2) Near IR multiobject spectrometer, 1 - 5 micrometer, and 3) Mid IR camera and spectrometer, 5 - 28 micrometers. I will report on the scientific goals, project status, and the recent reduction in aperture from the target of 8 m.

Seeking a Human Spaceflight Program Worthy of a Great Nation. Review of U.S. Human Spaceflight Plans Committee

DTIC Science & Technology

2009-10-01

human spaceflight plan is its affordability. In the way of background , Fig- ures 1-4, 1- 5 and 1-6 present the overall NASA bud- get trend over time...build upon the experience gained from prior ones. All as- sume a first flight to lunar orbit, and then to the Lagrange points, and then to near-Earth...and a description of the scenarios considered for inclusion in the integrated options presented in this report. 4.1.1 Background . The Space

Lagrange formula for differential operators on a tree-graph and the resolvents of well-posed restrictions of operator

NASA Astrophysics Data System (ADS)

Koshkarbayev, Nurbol; Kanguzhin, Baltabek

2017-09-01

In this paper we study the question on the full description of well-posed restrictions of given maximal differential operator on a tree-graph. Lagrange formula for differential operator on a tree with Kirchhoff conditions at its internal vertices is presented.

Symbolic computation of the Birkhoff normal form in the problem of stability of the triangular libration points

NASA Astrophysics Data System (ADS)

Shevchenko, I. I.

2008-05-01

The problem of stability of the triangular libration points in the planar circular restricted three-body problem is considered. A software package, intended for normalization of autonomous Hamiltonian systems by means of computer algebra, is designed so that normalization problems of high analytical complexity could be solved. It is used to obtain the Birkhoff normal form of the Hamiltonian in the given problem. The normalization is carried out up to the 6th order of expansion of the Hamiltonian in the coordinates and momenta. Analytical expressions for the coefficients of the normal form of the 6th order are derived. Though intermediary expressions occupy gigabytes of the computer memory, the obtained coefficients of the normal form are compact enough for presentation in typographic format. The analogue of the Deprit formula for the stability criterion is derived in the 6th order of normalization. The obtained floating-point numerical values for the normal form coefficients and the stability criterion confirm the results by Markeev (1969) and Coppola and Rand (1989), while the obtained analytical and exact numeric expressions confirm the results by Meyer and Schmidt (1986) and Schmidt (1989). The given computational problem is solved without constructing a specialized algebraic processor, i.e., the designed computer algebra package has a broad field of applicability.

Simulations of Dissipative Circular Restricted Three-body Problems Using the Velocity-scaling Correction Method

NASA Astrophysics Data System (ADS)

Wang, Shoucheng; Huang, Guoqing; Wu, Xin

2018-02-01

In this paper, we survey the effect of dissipative forces including radiation pressure, Poynting–Robertson drag, and solar wind drag on the motion of dust grains with negligible mass, which are subjected to the gravities of the Sun and Jupiter moving in circular orbits. The effect of the dissipative parameter on the locations of five Lagrangian equilibrium points is estimated analytically. The instability of the triangular equilibrium point L4 caused by the drag forces is also shown analytically. In this case, the Jacobi constant varies with time, whereas its integral invariant relation still provides a probability for the applicability of the conventional fourth-order Runge–Kutta algorithm combined with the velocity scaling manifold correction scheme. Consequently, the velocity-only correction method significantly suppresses the effects of artificial dissipation and a rapid increase in trajectory errors caused by the uncorrected one. The stability time of an orbit, regardless of whether it is chaotic or not in the conservative problem, is apparently longer in the corrected case than in the uncorrected case when the dissipative forces are included. Although the artificial dissipation is ruled out, the drag dissipation leads to an escape of grains. Numerical evidence also demonstrates that more orbits near the triangular equilibrium point L4 escape as the integration time increases.

Evidence for a spinon Fermi surface in a triangular-lattice quantum-spin-liquid candidate

DOE PAGES

Shen, Yao; Li, Yao-Dong; Wo, Hongliang; ...

2016-12-05

A quantum spin liquid is an exotic quantum state of matter in which spins are highly entangled and remain disordered down to zero temperature. Such a state of matter is potentially relevant to high-temperature superconductivity and quantum-information applications, and experimental identification of a quantum spin liquid state is of fundamental importance for our understanding of quantum matter. Theoretical studies have proposed various quantum-spin-liquid ground states, most of which are characterized by exotic spin excitations with fractional quantum numbers (termed ‘spinons’). In this paper, we report neutron scattering measurements of the triangular-lattice antiferromagnet YbMgGaO 4 that reveal broad spin excitations coveringmore » a wide region of the Brillouin zone. The observed diffusive spin excitation persists at the lowest measured energy and shows a clear upper excitation edge, consistent with the particle–hole excitation of a spinon Fermi surface. Finally, our results therefore point to the existence of a quantum spin liquid state with a spinon Fermi surface in YbMgGaO 4, which has a perfect spin-1/2 triangular lattice as in the original proposal of quantum spin liquids.« less

Cavity mode enhancement of terahertz emission from equilateral triangular microstrip antennas of the high-T c superconductor Bi2Sr2CaCu2O8 + δ

NASA Astrophysics Data System (ADS)

Cerkoney, Daniel P.; Reid, Candy; Doty, Constance M.; Gramajo, Ashley; Campbell, Tyler D.; Morales, Manuel A.; Delfanazari, Kaveh; Tsujimoto, Manabu; Kashiwagi, Takanari; Yamamoto, Takashi; Watanabe, Chiharu; Minami, Hidetoshi; Kadowaki, Kazuo; Klemm, Richard A.

2017-01-01

We study the transverse magnetic (TM) electromagnetic cavity mode wave functions for an ideal equilateral triangular microstrip antenna (MSA) exhibiting C 3v point group symmetry. When the C 3v operations are imposed upon the antenna, the TM(m,n) modes with wave vectors \\propto \\sqrt{{{m}2}+nm+{{n}2}} are much less dense than commonly thought. The R 3 operations restrict the integral n and m to satisfy |m-n| =3p , where p≥slant 0 and p≥slant 1 for the modes even and odd under reflections about the three mirror planes, respectively. We calculate the forms of representative wave functions and the angular dependence of the output power when these modes are excited by the uniform and non-uniform ac Josephson current sources in thin, ideally equilateral triangular MSAs employing the intrinsic Josephson junctions in the high transition temperature T c superconductor Bi2Sr2CaCu2 {{\\text{O}}8+δ} , and fit the emissions data from an earlier sample for which the C 3v symmetry was apparently broken.

One dimensionalization in the spin-1 Heisenberg model on the anisotropic triangular lattice

NASA Astrophysics Data System (ADS)

Gonzalez, M. G.; Ghioldi, E. A.; Gazza, C. J.; Manuel, L. O.; Trumper, A. E.

2017-11-01

We investigate the effect of dimensional crossover in the ground state of the antiferromagnetic spin-1 Heisenberg model on the anisotropic triangular lattice that interpolates between the regime of weakly coupled Haldane chains (J'≪J ) and the isotropic triangular lattice (J'=J ). We use the density-matrix renormalization group (DMRG) and Schwinger boson theory performed at the Gaussian correction level above the saddle-point solution. Our DMRG results show an abrupt transition between decoupled spin chains and the spirally ordered regime at (J'/J) c˜0.42 , signaled by the sudden closing of the spin gap. Coming from the magnetically ordered side, the computation of the spin stiffness within Schwinger boson theory predicts the instability of the spiral magnetic order toward a magnetically disordered phase with one-dimensional features at (J'/J) c˜0.43 . The agreement of these complementary methods, along with the strong difference found between the intra- and the interchain DMRG short spin-spin correlations for sufficiently large values of the interchain coupling, suggests that the interplay between the quantum fluctuations and the dimensional crossover effects gives rise to the one-dimensionalization phenomenon in this frustrated spin-1 Hamiltonian.

Philtral columns and nostril shapes in nigerian children: a morphometric and aesthetic analysis.

PubMed

Abdulrasheed, Ibrahim; Eneye, Asuku Malachy

2013-01-01

Background. The upper lip-nose complex contributes significantly to the concept of symmetry and proportion of the face. A study of the morphology and aesthetic preferences of the lip-nose complex will provide a database that will serve as a guide for reconstruction. Subjects and Methods. Hundred Nigerian children participated in this study. Demographic data and standard photographs of the philtral column and nostrils were obtained. Sixty volunteers were recruited to evaluate the photographs. Each volunteer was asked to rank the photographs based on their aesthetic preference. Results. The morphology of the philtral columns was classified into four groups: (1) triangular, (2) concave, (3) flat, and (4) parallel. The nostril shape was also classified into four groups: (1) triangular, (2) round, (3) teardrop, and (4) rectangular. In both genders, the triangular shape of philtral column was the most common. There are significant age differences in the aesthetic rankings of philtral columns and nostril shapes. Conclusion. Our study establishes the basal values for the morphometric and aesthetic parameters of the lip-nose complex of 5- and 6-year-old children in Nigeria. We hope our results and reconstructive surgery will intersect at a point to treat disfigurements of the philtrum and nostrils successfully.

Surface sampling techniques for 3D object inspection

NASA Astrophysics Data System (ADS)

Shih, Chihhsiong S.; Gerhardt, Lester A.

1995-03-01

While the uniform sampling method is quite popular for pointwise measurement of manufactured parts, this paper proposes three novel sampling strategies which emphasize 3D non-uniform inspection capability. They are: (a) the adaptive sampling, (b) the local adjustment sampling, and (c) the finite element centroid sampling techniques. The adaptive sampling strategy is based on a recursive surface subdivision process. Two different approaches are described for this adaptive sampling strategy. One uses triangle patches while the other uses rectangle patches. Several real world objects were tested using these two algorithms. Preliminary results show that sample points are distributed more closely around edges, corners, and vertices as desired for many classes of objects. Adaptive sampling using triangle patches is shown to generally perform better than both uniform and adaptive sampling using rectangle patches. The local adjustment sampling strategy uses a set of predefined starting points and then finds the local optimum position of each nodal point. This method approximates the object by moving the points toward object edges and corners. In a hybrid approach, uniform points sets and non-uniform points sets, first preprocessed by the adaptive sampling algorithm on a real world object were then tested using the local adjustment sampling method. The results show that the initial point sets when preprocessed by adaptive sampling using triangle patches, are moved the least amount of distance by the subsequently applied local adjustment method, again showing the superiority of this method. The finite element sampling technique samples the centroids of the surface triangle meshes produced from the finite element method. The performance of this algorithm was compared to that of the adaptive sampling using triangular patches. The adaptive sampling with triangular patches was once again shown to be better on different classes of objects.

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

Jimenez, Bienvenido; Novo, Vicente

We provide second-order necessary and sufficient conditions for a point to be an efficient element of a set with respect to a cone in a normed space, so that there is only a small gap between necessary and sufficient conditions. To this aim, we use the common second-order tangent set and the asymptotic second-order cone utilized by Penot. As an application we establish second-order necessary conditions for a point to be a solution of a vector optimization problem with an arbitrary feasible set and a twice Frechet differentiable objective function between two normed spaces. We also establish second-order sufficient conditionsmore » when the initial space is finite-dimensional so that there is no gap with necessary conditions. Lagrange multiplier rules are also given.« less

A Free-Return Earth-Moon Cycler Orbit for an Interplanetary Cruise Ship

NASA Technical Reports Server (NTRS)

Genova, Anthony L.; Aldrin, Buzz

2015-01-01

A periodic circumlunar orbit is presented that can be used by an interplanetary cruise ship for regular travel between Earth and the Moon. This Earth-Moon cycler orbit was revealed by introducing solar gravity and modest phasing maneuvers (average of 39 m/s per month) which yields close-Earth encounters every 7 or 10 days. Lunar encounters occur every 26 days and offer the chance for a smaller craft to depart the cycler and enter lunar orbit, or head for a Lagrange point (e.g., EM-L2 halo orbit), distant retrograde orbit (DRO), or interplanetary destination such as a near-Earth object (NEO) or Mars. Additionally, return-to-Earth abort options are available from many points along the cycling trajectory.

Interpretive Overview of Cultural Resources in Saylorville Lake, Iowa. Volume 1,

DTIC Science & Technology

1985-09-01

Rice Corner Notched variety; CN9, Turin variety). Similar side notched points were found in horizons I and II at the Cherokee Sewer site (Anderson...1980) and in the Middle Archaic levels at Koster (Brown and Vierra 1983:182-4) and the Pigeon Roost Creek site (O’Brien and Warren 1983). The Rice ...triangular blades are like the Rice Corner Notched style of the Archaic periods. Slightly smaller Manker Corner Notched points (Figures A.6, A.13) are

Bounded state variables and the calculus of variations

NASA Technical Reports Server (NTRS)

Hanafy, L. M.

1972-01-01

An optimal control problem with bounded state variables is transformed into a Lagrange problem by means of differentiable mappings which take some Euclidean space onto the control and state regions. Whereas all such mappings lead to a Lagrange problem, it is shown that only those which are defined as acceptable pairs of transformations are suitable in the sense that solutions to the transformed Lagrange problem will lead to solutions to the original bounded state problem and vice versa. In particular, an acceptable pair of transformations is exhibited for the case when the control and state regions are right parallelepipeds. Finally, a description of the necessary conditions for the bounded state problem which were obtained by this method is given.

Technique to eliminate computational instability in multibody simulations employing the Lagrange multiplier

NASA Technical Reports Server (NTRS)

Watts, G.

1992-01-01

A programming technique to eliminate computational instability in multibody simulations that use the Lagrange multiplier is presented. The computational instability occurs when the attached bodies drift apart and violate the constraints. The programming technique uses the constraint equation, instead of integration, to determine the coordinates that are not independent. Although the equations of motion are unchanged, a complete derivation of the incorporation of the Lagrange multiplier into the equation of motion for two bodies is presented. A listing of a digital computer program which uses the programming technique to eliminate computational instability is also presented. The computer program simulates a solid rocket booster and parachute connected by a frictionless swivel.

New similarity of triangular fuzzy number and its application.

PubMed

Zhang, Xixiang; Ma, Weimin; Chen, Liping

2014-01-01

The similarity of triangular fuzzy numbers is an important metric for application of it. There exist several approaches to measure similarity of triangular fuzzy numbers. However, some of them are opt to be large. To make the similarity well distributed, a new method SIAM (Shape's Indifferent Area and Midpoint) to measure triangular fuzzy number is put forward, which takes the shape's indifferent area and midpoint of two triangular fuzzy numbers into consideration. Comparison with other similarity measurements shows the effectiveness of the proposed method. Then, it is applied to collaborative filtering recommendation to measure users' similarity. A collaborative filtering case is used to illustrate users' similarity based on cloud model and triangular fuzzy number; the result indicates that users' similarity based on triangular fuzzy number can obtain better discrimination. Finally, a simulated collaborative filtering recommendation system is developed which uses cloud model and triangular fuzzy number to express users' comprehensive evaluation on items, and result shows that the accuracy of collaborative filtering recommendation based on triangular fuzzy number is higher.

Triangular Resection of the Upper Lateral Cartilage for Middle Vault Deviation.

PubMed

Ryu, Gwanghui; Seo, Min Young; Lee, Kyung Eun; Hong, Sang Duk; Chung, Seung-Kyu; Dhong, Hun-Jong; Kim, Hyo Yeol

2018-06-02

Middle vault deviation has a significant effect on the aesthetic and functional aspects of the nose, and its management continues to be a challenge. Spreader graft and its modification techniques have been focused, but there has been scarce consideration for removing surplus portion and balancing the upper lateral cartilage (ULC). This study aimed to report the newly invented triangular-shaped resection technique ("triangular resection") of the ULC and to evaluate its efficacy for correcting middle vault deviation. A retrospective study included 17 consecutive patients who presented with middle vault deviation and underwent septorhinoplasty by using triangular resection at a tertiary academic hospital from February 2014 and March 2016. Their outcomes were evaluated pre- and postoperatively including medical photographs, acoustic rhinometry and subjective nasal obstruction using a 7-point Likert scale. The immediate outcomes were evaluated around 1 month after surgery, and long-term outcomes were available in 12 patients; the mean follow-up period was 9.1 months. Nasal tip deviation angle was reduced from 5.66º to 2.37º immediately (P<0.001). Middle vault deviation also improved from 169.50º to 177.24º (P<0.001). Long-term results were 2.49º (P=0.015) for nasal tip deviation and 178.68º (P=0.002) for middle vault deviation. The aesthetic outcome involved a complete correction in eight patients (47.1%), a minimally visible deviation in seven patients (41.2%) and a remaining residual deviation in two patients (11.8%). Pre- and postoperative minimal cross-sectional areas (summation of the right and left sides) were 0.86 and 1.07, respectively (P=0.021). Fifteen patients answered about their nasal obstruction symptoms and the median symptom score had alleviated from 6.0 to 3.0 (P=0.004). Triangular resection of the ULC is a simple and effective method for correcting middle vault deviation and balancing the ULCs without complications as internal nasal valve narrowing.

Advances in understanding quiescent H-mode plasmas in DIII-Da)

NASA Astrophysics Data System (ADS)

Burrell, K. H.; West, W. P.; Doyle, E. J.; Austin, M. E.; Casper, T. A.; Gohil, P.; Greenfield, C. M.; Groebner, R. J.; Hyatt, A. W.; Jayakumar, R. J.; Kaplan, D. H.; Lao, L. L.; Leonard, A. W.; Makowski, M. A.; McKee, G. R.; Osborne, T. H.; Snyder, P. B.; Solomon, W. M.; Thomas, D. M.; Rhodes, T. L.; Strait, E. J.; Wade, M. R.; Wang, G.; Zeng, L.

2005-05-01

Recent QH-mode research on DIII-D [J. L. Luxon et al., Plasma Physics and Controlled Nuclear Fusion Research 1996 (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159] has used the peeling-ballooning modes model of edge magnetohydrodynamic stability as a working hypothesis to organize the data; several predictions of this theory are consistent with the experimental results. Current ramping results indicate that QH modes operate near the edge current limit set by peeling modes. This operating point explains why QH mode is easier to get at lower plasma currents. Power scans have shown a saturation of edge pressure with increasing power input. This allows QH-mode plasmas to remain stable to edge localized modes (ELMs) to the highest powers used in DIII-D. At present, the mechanism for this saturation is unknown; if the edge harmonic oscillation (EHO) is playing a role here, the physics is not a simple amplitude dependence. The increase in edge stability with plasma triangularity predicted by the peeling-ballooning theory is consistent with the substantial improvement in pedestal pressure achieved by changing the plasma shape from a single null divertor to a high triangularity double null. Detailed ELITE calculations for the high triangularity plasmas have demonstrated that the plasma operating point is marginally stable to peeling-ballooning modes. Comparison of ELMing, coinjected and quiescent, counterinjected discharges with the same shape, current, toroidal field, electron density, and electron temperature indicates that the edge radial electric field or the edge toroidal rotation are also playing a role in edge stability. The EHO produces electron, main ion, and impurity particle transport at the plasma edge which is more rapid than that produced by ELMs under similar conditions. The EHO also decreases the edge rotation while producing little change in the edge electron and ion temperatures. Other edge electromagnetic modes also produce particle transport; this includes the incoherent, broadband activity seen at high triangularity. Pedestal values of ν* and βT bracketing, those required for International Experimental Thermonuclear Reactor [Nucl. Fusion 39, 2137 (1999)] have been achieved in DIII-D, demonstrating the QH-mode edge densities are sufficient for future devices.

Advances in understanding quiescent H-mode plasmas in DIII-D

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

Burrell, K.H.; West, W.P.; Gohil, P.

2005-05-15

Recent QH-mode research on DIII-D [J. L. Luxon et al., Plasma Physics and Controlled Nuclear Fusion Research 1996 (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159] has used the peeling-ballooning modes model of edge magnetohydrodynamic stability as a working hypothesis to organize the data; several predictions of this theory are consistent with the experimental results. Current ramping results indicate that QH modes operate near the edge current limit set by peeling modes. This operating point explains why QH mode is easier to get at lower plasma currents. Power scans have shown a saturation of edge pressure with increasingmore » power input. This allows QH-mode plasmas to remain stable to edge localized modes (ELMs) to the highest powers used in DIII-D. At present, the mechanism for this saturation is unknown; if the edge harmonic oscillation (EHO) is playing a role here, the physics is not a simple amplitude dependence. The increase in edge stability with plasma triangularity predicted by the peeling-ballooning theory is consistent with the substantial improvement in pedestal pressure achieved by changing the plasma shape from a single null divertor to a high triangularity double null. Detailed ELITE calculations for the high triangularity plasmas have demonstrated that the plasma operating point is marginally stable to peeling-ballooning modes. Comparison of ELMing, coinjected and quiescent, counterinjected discharges with the same shape, current, toroidal field, electron density, and electron temperature indicates that the edge radial electric field or the edge toroidal rotation are also playing a role in edge stability. The EHO produces electron, main ion, and impurity particle transport at the plasma edge which is more rapid than that produced by ELMs under similar conditions. The EHO also decreases the edge rotation while producing little change in the edge electron and ion temperatures. Other edge electromagnetic modes also produce particle transport; this includes the incoherent, broadband activity seen at high triangularity. Pedestal values of {nu}{sub *} and {beta}{sub T} bracketing, those required for International Experimental Thermonuclear Reactor [Nucl. Fusion 39, 2137 (1999)] have been achieved in DIII-D, demonstrating the QH-mode edge densities are sufficient for future devices.« less

Necessary conditions for weighted mean convergence of Lagrange interpolation for exponential weights

NASA Astrophysics Data System (ADS)

Damelin, S. B.; Jung, H. S.; Kwon, K. H.

2001-07-01

Given a continuous real-valued function f which vanishes outside a fixed finite interval, we establish necessary conditions for weighted mean convergence of Lagrange interpolation for a general class of even weights w which are of exponential decay on the real line or at the endpoints of (-1,1).

Visualizing and Understanding the Components of Lagrange and Newton Interpolation

ERIC Educational Resources Information Center

Yang, Yajun; Gordon, Sheldon P.

2016-01-01

This article takes a close look at Lagrange and Newton interpolation by graphically examining the component functions of each of these formulas. Although interpolation methods are often considered simply to be computational procedures, we demonstrate how the components of the polynomial terms in these formulas provide insight into where these…

An algorithm for propagating the square-root covariance matrix in triangular form

NASA Technical Reports Server (NTRS)

Tapley, B. D.; Choe, C. Y.

1976-01-01

A method for propagating the square root of the state error covariance matrix in lower triangular form is described. The algorithm can be combined with any triangular square-root measurement update algorithm to obtain a triangular square-root sequential estimation algorithm. The triangular square-root algorithm compares favorably with the conventional sequential estimation algorithm with regard to computation time.

Toward a New Method of Decoding Algebraic Codes Using Groebner Bases

DTIC Science & Technology

1993-10-01

variables over GF(2m). A celebrated algorithm by Buchberger produces a reduced Groebner basis of that ideal. It tums out that, since the common roots of...all the polynomials in the ideal are a set of isolated points, this reduced Groebner basis is in triangular form, and the univariate polynomial in that

Orbit period modulation for relative motion using continuous low thrust in the two-body and restricted three-body problems

NASA Astrophysics Data System (ADS)

Arnot, C. S.; McInnes, C. R.; McKay, R. J.; Macdonald, M.; Biggs, J.

2018-02-01

This paper presents rich new families of relative orbits for spacecraft formation flight generated through the application of continuous thrust with only minimal intervention into the dynamics of the problem. Such simplicity facilitates implementation for small, low-cost spacecraft with only position state feedback, and yet permits interesting and novel relative orbits in both two- and three-body systems with potential future applications in space-based interferometry, hyperspectral sensing, and on-orbit inspection. Position feedback is used to modify the natural frequencies of the linearised relative dynamics through direct manipulation of the system eigenvalues, producing new families of stable relative orbits. Specifically, in the Hill-Clohessy-Wiltshire frame, simple adaptations of the linearised dynamics are used to produce a circular relative orbit, frequency-modulated out-of-plane motion, and a novel doubly periodic cylindrical relative trajectory for the purposes of on-orbit inspection. Within the circular restricted three-body problem, a similar minimal approach with position feedback is used to generate new families of stable, frequency-modulated relative orbits in the vicinity of a Lagrange point, culminating in the derivation of the gain requirements for synchronisation of the in-plane and out-of-plane frequencies to yield a singly periodic tilted elliptical relative orbit with potential use as a Lunar far-side communications relay. The Δ v requirements for the cylindrical relative orbit and singly periodic Lagrange point orbit are analysed, and it is shown that these requirements are modest and feasible for existing low-thrust propulsion technology.

Evolutionary branching under multi-dimensional evolutionary constraints.

PubMed

Ito, Hiroshi; Sasaki, Akira

2016-10-21

The fitness of an existing phenotype and of a potential mutant should generally depend on the frequencies of other existing phenotypes. Adaptive evolution driven by such frequency-dependent fitness functions can be analyzed effectively using adaptive dynamics theory, assuming rare mutation and asexual reproduction. When possible mutations are restricted to certain directions due to developmental, physiological, or physical constraints, the resulting adaptive evolution may be restricted to subspaces (constraint surfaces) with fewer dimensionalities than the original trait spaces. To analyze such dynamics along constraint surfaces efficiently, we develop a Lagrange multiplier method in the framework of adaptive dynamics theory. On constraint surfaces of arbitrary dimensionalities described with equality constraints, our method efficiently finds local evolutionarily stable strategies, convergence stable points, and evolutionary branching points. We also derive the conditions for the existence of evolutionary branching points on constraint surfaces when the shapes of the surfaces can be chosen freely. Copyright © 2016 Elsevier Ltd. All rights reserved.

Triangular arbitrage in the foreign exchange market

NASA Astrophysics Data System (ADS)

Aiba, Yukihiro; Hatano, Naomichi

2004-12-01

We first review our previous work, showing what is the triangular arbitrage transaction and how to quantify the triangular arbitrage opportunity. Next we explain that the correlation of the foreign exchange rates can appear without actual triangular arbitrage transaction.

Magnetic and magnetocaloric properties of the exactly solvable mixed-spin Ising model on a decorated triangular lattice in a magnetic field

NASA Astrophysics Data System (ADS)

Gálisová, Lucia; Strečka, Jozef

2018-05-01

The ground state, zero-temperature magnetization process, critical behaviour and isothermal entropy change of the mixed-spin Ising model on a decorated triangular lattice in a magnetic field are exactly studied after performing the generalized decoration-iteration mapping transformation. It is shown that both the inverse and conventional magnetocaloric effect can be found near the absolute zero temperature. The former phenomenon can be found in a vicinity of the discontinuous phase transitions and their crossing points, while the latter one occurs in some paramagnetic phases due to a spin frustration to be present at zero magnetic field. The inverse magnetocaloric effect can also be detected slightly above continuous phase transitions following the power-law dependence | - ΔSisomin | ∝hn, where n depends basically on the ground-state spin ordering.

A Person Fit Test for IRT Models for Polytomous Items

ERIC Educational Resources Information Center

Glas, C. A. W.; Dagohoy, Anna Villa T.

2007-01-01

A person fit test based on the Lagrange multiplier test is presented for three item response theory models for polytomous items: the generalized partial credit model, the sequential model, and the graded response model. The test can also be used in the framework of multidimensional ability parameters. It is shown that the Lagrange multiplier…

Lagrange multiplier for perishable inventory model considering warehouse capacity planning

NASA Astrophysics Data System (ADS)

Amran, Tiena Gustina; Fatima, Zenny

2017-06-01

This paper presented Lagrange Muktiplier approach for solving perishable raw material inventory planning considering warehouse capacity. A food company faced an issue of managing perishable raw materials and marinades which have limited shelf life. Another constraint to be considered was the capacity of the warehouse. Therefore, an inventory model considering shelf life and raw material warehouse capacity are needed in order to minimize the company's inventory cost. The inventory model implemented in this study was the adapted economic order quantity (EOQ) model which is optimized using Lagrange multiplier. The model and solution approach were applied to solve a case industry in a food manufacturer. The result showed that the total inventory cost decreased 2.42% after applying the proposed approach.

Comparison of Numerical Modeling Methods for Soil Vibration Cutting

NASA Astrophysics Data System (ADS)

Jiang, Jiandong; Zhang, Enguang

2018-01-01

In this paper, we studied the appropriate numerical simulation method for vibration soil cutting. Three numerical simulation methods, commonly used for uniform speed soil cutting, Lagrange, ALE and DEM, are analyzed. Three models of vibration soil cutting simulation model are established by using ls-dyna.The applicability of the three methods to this problem is analyzed in combination with the model mechanism and simulation results. Both the Lagrange method and the DEM method can show the force oscillation of the tool and the large deformation of the soil in the vibration cutting. Lagrange method shows better effect of soil debris breaking. Because of the poor stability of ALE method, it is not suitable to use soil vibration cutting problem.

On some labelings of triangular snake and central graph of triangular snake graph

NASA Astrophysics Data System (ADS)

Agasthi, P.; Parvathi, N.

2018-04-01

A Triangular snake Tn is obtained from a path u 1 u 2 … u n by joining ui and u i+1 to a new vertex wi for 1≤i≤n‑1. A Central graph of Triangular snake C(T n ) is obtained by subdividing each edge of Tn exactly once and joining all the non adjacent vertices of Tn . In this paper the ways to construct square sum, square difference, Root Mean square, strongly Multiplicative, Even Mean and Odd Mean labeling for Triangular Snake and Central graph of Triangular Snake graphs are reported.

Strong-coupling analysis of two-dimensional O({ital N}) {sigma} models with {ital N}{le}2 on square, triangular, and honeycomb lattices

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

Campostrini, M.; Pelissetto, A.; Rossi, P.

1996-09-01

The critical behavior of two-dimensional (2D) O({ital N}) {sigma} models with {ital N}{le}2 on square, triangular, and honeycomb lattices is investigated by an analysis of the strong-coupling expansion of the two-point fundamental Green{close_quote}s function {ital G}({ital x}), calculated up to 21st order on the square lattice, 15th order on the triangular lattice, and 30th order on the honeycomb lattice. For {ital N}{lt}2 the critical behavior is of power-law type, and the exponents {gamma} and {nu} extracted from our strong-coupling analysis confirm exact results derived assuming universality with solvable solid-on-solid models. At {ital N}=2, i.e., for the 2D {ital XY} model,more » the results from all lattices considered are consistent with the Kosterlitz-Thouless exponential approach to criticality, characterized by an exponent {sigma}=1/2, and with universality. The value {sigma}=1/2 is confirmed within an uncertainty of few percent. The prediction {eta}=1/4 is also roughly verified. For various values of {ital N}{le}2, we determine some ratios of amplitudes concerning the two-point function {ital G}({ital x}) in the critical limit of the symmetric phase. This analysis shows that the low-momentum behavior of {ital G}({ital x}) in the critical region is essentially Gaussian at all values of {ital N}{le}2. Exact results for the long-distance behavior of {ital G}({ital x}) when {ital N}=1 (Ising model in the strong-coupling phase) confirm this statement. {copyright} {ital 1996 The American Physical Society.}« less

Deep Space Transportation System Using the Sun-Earth L2 Point

NASA Technical Reports Server (NTRS)

Matsumoto, Michihiro

2007-01-01

Recently, various kinds of planetary explorations have become more feasible, taking the advantage of low thrust propulsion means such as ion engines that have come into practical use. The field of space activity has now been expanded even to the rim of the outer solar system. In this context, the Japan Aerospace Exploration Agency (JAXA) has started investigating a Deep Space Port built at the L2 Lagrange point in the Sun-Earth system. For the purpose of making the deep space port practically useful, there is a need to establish a method to making spaceship depart and return from/to the port. This paper first discusses the escape maneuvers originating from the L2 point under the restricted three-body problem. Impulsive maneuvers from the L2 point are extensively studied here, and using the results, optimal low-thrust escape strategies are synthesized. Furthermore, this paper proposes the optimal escape and acceleration maneuvers schemes using Electric Delta-V Earth Gravity Assist (EDVEGA) technique.

Active and Passive Sensing from Geosynchronous and Libration Orbits

NASA Technical Reports Server (NTRS)

Schoeberl, Mark; Raymond, Carol; Hildebrand, Peter

2003-01-01

The development of the LEO (EOS) missions has led the way to new technologies and new science discoveries. However, LEO measurements alone cannot cost effectively produce high time resolution measurements needed to move the science to the next level. Both GEO and the Lagrange points, L1 and L2, provide vantage points that will allow higher time resolution measurements. GEO is currently being exploited by weather satellites, but the sensors currently operating at GEO do not provide the spatial or spectral resolution needed for atmospheric trace gas, ocean or land surface measurements. It is also may be possible to place active sensors in geostationary orbit. It seems clear, that the next era in earth observation and discovery will be opened by sensor systems operating beyond near earth orbit.

Mapping the cosmos

NASA Astrophysics Data System (ADS)

Clery, Daniel

2009-04-01

For the last seven years, NASA's Wilkinson Microwave Anisotropy Probe (WMAP) has kept a lonely vigil in an area in space some 1.5 million kilometres further out from the Sun beyond the Earth. Known as Lagrange point L2, it is where a space probe can usefully hover, little disturbed by stray signals from home and without having to use much fuel to keep it in position. But WMAP will soon have company: two groundbreaking missions from the European Space Agency (ESA), due to be launched on the same Ariane-5 rocket later this month, will take up their positions next to NASA's craft.

On the dynamics of chain systems. [applications in manipulator and human body models

NASA Technical Reports Server (NTRS)

Huston, R. L.; Passerello, C. E.

1974-01-01

A computer-oriented method for obtaining dynamical equations of motion for chain systems is presented. A chain system is defined as an arbitrarily assembled set of rigid bodies such that adjoining bodies have at least one common point and such that closed loops are not formed. The equations of motion are developed through the use of Lagrange's form of d'Alembert's principle. The method and procedure is illustrated with an elementary study of a tripod space manipulator. The method is designed for application with systems such as human body models, chains and cables, and dynamic finite-segment models.

Unified formalism for higher order non-autonomous dynamical systems

NASA Astrophysics Data System (ADS)

Prieto-Martínez, Pedro Daniel; Román-Roy, Narciso

2012-03-01

This work is devoted to giving a geometric framework for describing higher order non-autonomous mechanical systems. The starting point is to extend the Lagrangian-Hamiltonian unified formalism of Skinner and Rusk for these kinds of systems, generalizing previous developments for higher order autonomous mechanical systems and first-order non-autonomous mechanical systems. Then, we use this unified formulation to derive the standard Lagrangian and Hamiltonian formalisms, including the Legendre-Ostrogradsky map and the Euler-Lagrange and the Hamilton equations, both for regular and singular systems. As applications of our model, two examples of regular and singular physical systems are studied.

Explicitly computing geodetic coordinates from Cartesian coordinates

NASA Astrophysics Data System (ADS)

Zeng, Huaien

2013-04-01

This paper presents a new form of quartic equation based on Lagrange's extremum law and a Groebner basis under the constraint that the geodetic height is the shortest distance between a given point and the reference ellipsoid. A very explicit and concise formulae of the quartic equation by Ferrari's line is found, which avoids the need of a good starting guess for iterative methods. A new explicit algorithm is then proposed to compute geodetic coordinates from Cartesian coordinates. The convergence region of the algorithm is investigated and the corresponding correct solution is given. Lastly, the algorithm is validated with numerical experiments.

Split-step eigenvector-following technique for exploring enthalpy landscapes at absolute zero.

PubMed

Mauro, John C; Loucks, Roger J; Balakrishnan, Jitendra

2006-03-16

The mapping of enthalpy landscapes is complicated by the coupling of particle position and volume coordinates. To address this issue, we have developed a new split-step eigenvector-following technique for locating minima and transition points in an enthalpy landscape at absolute zero. Each iteration is split into two steps in order to independently vary system volume and relative atomic coordinates. A separate Lagrange multiplier is used for each eigendirection in order to provide maximum flexibility in determining step sizes. This technique will be useful for mapping the enthalpy landscapes of bulk systems such as supercooled liquids and glasses.

Evaluation of the AFWA WRF 4-KM Moving Nest Model Predictions for Western North Pacific Tropical Cyclones

DTIC Science & Technology

2006-03-01

16 3. Typhoon Mawar ..................................................................... 19 4. Typhoon Talim...From: Digital Typhoon website) Infrared satellite image of Tropical Storm Mawar (center) and the seedling convection of what would become...Typhoon Mawar . The red triangular points represent the period covered by the two 72-h ARW integrations. The large red dot indicates the ending time of

33 CFR 334.1330 - Bering Strait, Alaska; naval restricted area off Cape Prince of Wales.

Code of Federal Regulations, 2010 CFR

2010-07-01

... restricted area off Cape Prince of Wales. 334.1330 Section 334.1330 Navigation and Navigable Waters CORPS OF....1330 Bering Strait, Alaska; naval restricted area off Cape Prince of Wales. (a) The area. An area 2,000 feet wide extending from a point on Cape Prince of Wales marked by a triangular cable marker located...

Bone Pose Estimation in the Presence of Soft Tissue Artifact Using Triangular Cosserat Point Elements.

PubMed

Solav, Dana; Rubin, M B; Cereatti, Andrea; Camomilla, Valentina; Wolf, Alon

2016-04-01

Accurate estimation of the position and orientation (pose) of a bone from a cluster of skin markers is limited mostly by the relative motion between the bone and the markers, which is known as the soft tissue artifact (STA). This work presents a method, based on continuum mechanics, to describe the kinematics of a cluster affected by STA. The cluster is characterized by triangular cosserat point elements (TCPEs) defined by all combinations of three markers. The effects of the STA on the TCPEs are quantified using three parameters describing the strain in each TCPE and the relative rotation and translation between TCPEs. The method was evaluated using previously collected ex vivo kinematic data. Femur pose was estimated from 12 skin markers on the thigh, while its reference pose was measured using bone pins. Analysis revealed that instantaneous subsets of TCPEs exist which estimate bone position and orientation more accurately than the Procrustes Superimposition applied to the cluster of all markers. It has been shown that some of these parameters correlate well with femur pose errors, which suggests that they can be used to select, at each instant, subsets of TCPEs leading an improved estimation of the underlying bone pose.

Thermal Entanglement in XXZ Heisenberg Model for Coupled Spin-Half and Spin-One Triangular Cell

NASA Astrophysics Data System (ADS)

Najarbashi, Ghader; Balazadeh, Leila; Tavana, Ali

2018-01-01

In this paper, we investigate the thermal entanglement of two-spin subsystems in an ensemble of coupled spin-half and spin-one triangular cells, (1/2, 1/2, 1/2), (1/2, 1, 1/2), (1, 1/2, 1) and (1, 1, 1) with the XXZ anisotropic Heisenberg model subjected to an external homogeneous magnetic field. We adopt the generalized concurrence as the measure of entanglement which is a good indicator of the thermal entanglement and the critical points in the mixed higher dimensional spin systems. We observe that in the near vicinity of the absolute zero, the concurrence measure is symmetric with respect to zero magnetic field and changes abruptly from a non-null to null value for a critical magnetic field that can be signature of a quantum phase transition at finite temperature. The analysis of concurrence versus temperature shows that there exists a critical temperature, that depends on the type of the interaction, i.e. ferromagnetic or antiferromagnetic, the anisotropy parameter and the strength of the magnetic field. Results show that the pairwise thermal entanglement depends on the third spin which affects the maximum value of the concurrence at absolute zero and at quantum critical points.

A possible space VLBI constellation utilizing the stable orbits around the TLPs in the Earth-Moon system.

NASA Astrophysics Data System (ADS)

Liu, Bin; Tang, Jingshi; Hou, Xiyun

2016-07-01

Current studies indicate that there are stable orbits around but far away from the triangular libration points .Two special quasi-periodic orbits around each triangular libration points L4 , L5 in the Earth-Moon sys-tem perturbed by Sun are gain , and the stable orbits discussed in this work are ideal places for space colonies because no orbit control is needed. These stable orbits can also be used as nominal orbits for space VLBI (Very Long Baseline Interferometry) stations. The two stations can also form baselines with stations on the Earth and the Moon, or with stations located around another TLP. Due to the long distance between the stations, the observation precision can be greatly enhanced compared with the VLBI stations on the Earth. Such a VLBI constellation not only can advance the radio astronomy, but also can be used as a navigation system for human activities in the Earth-Moon system and even in the solar system. This paper will focus on the navigation constellation coverage issues, and the orbit determination accuracy problems within the Earth-Moon sys-tem and interplanetary space.

Investigation of a Structural Phase Transition and Magnetic Structure of Na 2BaFe(VO 4) 2: A Triangular Magnetic Lattice with a Ferromagnetic Ground State

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

Sanjeewa, Liurukara D.; Garlea, Vasile O.; McGuire, Michael A.

The structural and magnetic properties of a glaserite-type Na 2BaFe(VO 4) 2 compound, featuring a triangular magnetic lattice of Fe 2+ (S = 2), are reported. Temperature dependent X-ray single crystal studies indicate that at room temperature the system adopts a trigonal Pmore » $$\\bar{3}$$ m1 structure and undergoes a structural phase transition to a C2/c monoclinic phase slightly below room temperature (T s = 288 K). This structural transition involves a tilting of Fe–O–V bond angles and strongly influences the magnetic correlation within the Fe triangular lattice. The magnetic susceptibility measurements reveal a ferromagnetic transition near 7 K. Single crystal neutron diffraction confirms the structural distortion and the ferromagnetic spin ordering in Na 2BaFe(VO 4) 2. The magnetic structure of the ordered state is modeled in the magnetic space group C2'/c' that implies a ferromagnetic order of the a and c moment components and antiferromagnetic arrangement for the b components. Altogether, the Fe magnetic moments form ferromagnetic layers that are stacked along the c-axis, where the spins point along one of the (111) facets of the FeO 6 octahedron.« less

Absence of Long-Range Order in a Triangular Spin System with Dipolar Interactions

NASA Astrophysics Data System (ADS)

Keleş, Ahmet; Zhao, Erhai

2018-05-01

The antiferromagnetic Heisenberg model on the triangular lattice is perhaps the best known example of frustrated magnets, but it orders at low temperatures. Recent density matrix renormalization group (DMRG) calculations find that the next nearest neighbor interaction J2 enhances the frustration, and it leads to a spin liquid for J2/J1∈(0.08 ,0.15 ). In addition, a DMRG study of a dipolar Heisenberg model with longer range interactions gives evidence for a spin liquid at a small dipole tilting angle θ ∈[0 ,1 0 ° ). In both cases, the putative spin liquid region appears to be small. Here, we show that for the triangular lattice dipolar Heisenberg model, a robust quantum paramagnetic phase exists in a surprisingly wide region, θ ∈[0 ,5 4 ° ) , for dipoles tilted along the lattice diagonal direction. We obtain the phase diagram of the model by functional renormalization group (RG), which treats all magnetic instabilities on equal footing. The quantum paramagnetic phase is characterized by a smooth continuous flow of vertex functions and spin susceptibility down to the lowest RG scale, in contrast to the apparent breakdown of RG flow in phases with stripe or spiral order. Our finding points to a promising direction to search for quantum spin liquids in ultracold dipolar molecules.

Investigation of a Structural Phase Transition and Magnetic Structure of Na 2BaFe(VO 4) 2: A Triangular Magnetic Lattice with a Ferromagnetic Ground State

DOE PAGES

Sanjeewa, Liurukara D.; Garlea, Vasile O.; McGuire, Michael A.; ...

2017-12-07

The structural and magnetic properties of a glaserite-type Na 2BaFe(VO 4) 2 compound, featuring a triangular magnetic lattice of Fe 2+ (S = 2), are reported. Temperature dependent X-ray single crystal studies indicate that at room temperature the system adopts a trigonal Pmore » $$\\bar{3}$$ m1 structure and undergoes a structural phase transition to a C2/c monoclinic phase slightly below room temperature (T s = 288 K). This structural transition involves a tilting of Fe–O–V bond angles and strongly influences the magnetic correlation within the Fe triangular lattice. The magnetic susceptibility measurements reveal a ferromagnetic transition near 7 K. Single crystal neutron diffraction confirms the structural distortion and the ferromagnetic spin ordering in Na 2BaFe(VO 4) 2. The magnetic structure of the ordered state is modeled in the magnetic space group C2'/c' that implies a ferromagnetic order of the a and c moment components and antiferromagnetic arrangement for the b components. Altogether, the Fe magnetic moments form ferromagnetic layers that are stacked along the c-axis, where the spins point along one of the (111) facets of the FeO 6 octahedron.« less

Pairwise-interaction extended point-particle model for particle-laden flows

NASA Astrophysics Data System (ADS)

Akiki, G.; Moore, W. C.; Balachandar, S.

2017-12-01

In this work we consider the pairwise interaction extended point-particle (PIEP) model for Euler-Lagrange simulations of particle-laden flows. By accounting for the precise location of neighbors the PIEP model goes beyond local particle volume fraction, and distinguishes the influence of upstream, downstream and laterally located neighbors. The two main ingredients of the PIEP model are (i) the undisturbed flow at any particle is evaluated as a superposition of the macroscale flow and a microscale flow that is approximated as a pairwise superposition of perturbation fields induced by each of the neighboring particles, and (ii) the forces and torque on the particle are then calculated from the undisturbed flow using the Faxén form of the force relation. The computational efficiency of the standard Euler-Lagrange approach is retained, since the microscale perturbation fields induced by a neighbor are pre-computed and stored as PIEP maps. Here we extend the PIEP force model of Akiki et al. [3] with a corresponding torque model to systematically include the effect of perturbation fields induced by the neighbors in evaluating the net torque. Also, we use DNS results from a uniform flow over two stationary spheres to further improve the PIEP force and torque models. We then test the PIEP model in three different sedimentation problems and compare the results against corresponding DNS to assess the accuracy of the PIEP model and improvement over the standard point-particle approach. In the case of two sedimenting spheres in a quiescent ambient the PIEP model is shown to capture the drafting-kissing-tumbling process. In cases of 5 and 80 sedimenting spheres a good agreement is obtained between the PIEP simulation and the DNS. For all three simulations, the DEM-PIEP was able to recreate, to a good extent, the results from the DNS, while requiring only a negligible fraction of the numerical resources required by the fully-resolved DNS.

Dynamical computation of constrained flexible systems using a modal Udwadia-Kalaba formulation: Application to musical instruments.

PubMed

Antunes, J; Debut, V

2017-02-01

Most musical instruments consist of dynamical subsystems connected at a number of constraining points through which energy flows. For physical sound synthesis, one important difficulty deals with enforcing these coupling constraints. While standard techniques include the use of Lagrange multipliers or penalty methods, in this paper, a different approach is explored, the Udwadia-Kalaba (U-K) formulation, which is rooted on analytical dynamics but avoids the use of Lagrange multipliers. This general and elegant formulation has been nearly exclusively used for conceptual systems of discrete masses or articulated rigid bodies, namely, in robotics. However its natural extension to deal with continuous flexible systems is surprisingly absent from the literature. Here, such a modeling strategy is developed and the potential of combining the U-K equation for constrained systems with the modal description is shown, in particular, to simulate musical instruments. Objectives are twofold: (1) Develop the U-K equation for constrained flexible systems with subsystems modelled through unconstrained modes; and (2) apply this framework to compute string/body coupled dynamics. This example complements previous work [Debut, Antunes, Marques, and Carvalho, Appl. Acoust. 108, 3-18 (2016)] on guitar modeling using penalty methods. Simulations show that the proposed technique provides similar results with a significant improvement in computational efficiency.

Synoptic ozone, cloud reflectivity, and erythemal irradiance from sunrise to sunset for the whole earth as viewed by the DSCOVR spacecraft from the earth-sun Lagrange 1 orbit

NASA Astrophysics Data System (ADS)

Herman, Jay; Huang, Liang; McPeters, Richard; Ziemke, Jerry; Cede, Alexander; Blank, Karin

2018-01-01

EPIC (Earth Polychromatic Imaging Camera) on board the DSCOVR (Deep Space Climate Observatory) spacecraft is the first earth science instrument located near the earth-sun gravitational plus centrifugal force balance point, Lagrange 1. EPIC measures earth-reflected radiances in 10 wavelength channels ranging from 317.5 to 779.5 nm. Of these channels, four are in the UV range 317.5, 325, 340, and 388 nm, which are used to retrieve O3, 388 nm scene reflectivity (LER: Lambert equivalent reflectivity), SO2, and aerosol properties. These new synoptic quantities are retrieved for the entire sunlit globe from sunrise to sunset multiple times per day as the earth rotates in EPIC's field of view. Retrieved ozone amounts agree with ground-based measurements and satellite data to within 3 %. The ozone amounts and LER are combined to derive the erythemal irradiance for the earth's entire sunlit surface at a nadir resolution of 18 × 18 km2 using a computationally efficient approximation to a radiative transfer calculation of irradiance. The results show very high summertime values of the UV index (UVI) in the Andes and Himalayas (greater than 18), and high values of UVI near the Equator at equinox.

Application of shifted Jacobi pseudospectral method for solving (in)finite-horizon min-max optimal control problems with uncertainty

NASA Astrophysics Data System (ADS)

Nikooeinejad, Z.; Delavarkhalafi, A.; Heydari, M.

2018-03-01

The difficulty of solving the min-max optimal control problems (M-MOCPs) with uncertainty using generalised Euler-Lagrange equations is caused by the combination of split boundary conditions, nonlinear differential equations and the manner in which the final time is treated. In this investigation, the shifted Jacobi pseudospectral method (SJPM) as a numerical technique for solving two-point boundary value problems (TPBVPs) in M-MOCPs for several boundary states is proposed. At first, a novel framework of approximate solutions which satisfied the split boundary conditions automatically for various boundary states is presented. Then, by applying the generalised Euler-Lagrange equations and expanding the required approximate solutions as elements of shifted Jacobi polynomials, finding a solution of TPBVPs in nonlinear M-MOCPs with uncertainty is reduced to the solution of a system of algebraic equations. Moreover, the Jacobi polynomials are particularly useful for boundary value problems in unbounded domain, which allow us to solve infinite- as well as finite and free final time problems by domain truncation method. Some numerical examples are given to demonstrate the accuracy and efficiency of the proposed method. A comparative study between the proposed method and other existing methods shows that the SJPM is simple and accurate.

General invertible transformation and physical degrees of freedom

NASA Astrophysics Data System (ADS)

Takahashi, Kazufumi; Motohashi, Hayato; Suyama, Teruaki; Kobayashi, Tsutomu

2017-04-01

An invertible field transformation is such that the old field variables correspond one-to-one to the new variables. As such, one may think that two systems that are related by an invertible transformation are physically equivalent. However, if the transformation depends on field derivatives, the equivalence between the two systems is nontrivial due to the appearance of higher derivative terms in the equations of motion. To address this problem, we prove the following theorem on the relation between an invertible transformation and Euler-Lagrange equations: If the field transformation is invertible, then any solution of the original set of Euler-Lagrange equations is mapped to a solution of the new set of Euler-Lagrange equations, and vice versa. We also present applications of the theorem to scalar-tensor theories.

Generalizing boundaries for triangular designs, and efficacy estimation at extended follow-ups.

PubMed

Allison, Annabel; Edwards, Tansy; Omollo, Raymond; Alves, Fabiana; Magirr, Dominic; E Alexander, Neal D

2015-11-16

Visceral leishmaniasis (VL) is a parasitic disease transmitted by sandflies and is fatal if left untreated. Phase II trials of new treatment regimens for VL are primarily carried out to evaluate safety and efficacy, while pharmacokinetic data are also important to inform future combination treatment regimens. The efficacy of VL treatments is evaluated at two time points, initial cure, when treatment is completed and definitive cure, commonly 6 months post end of treatment, to allow for slow response to treatment and detection of relapses. This paper investigates a generalization of the triangular design to impose a minimum sample size for pharmacokinetic or other analyses, and methods to estimate efficacy at extended follow-up accounting for the sequential design and changes in cure status during extended follow-up. We provided R functions that generalize the triangular design to impose a minimum sample size before allowing stopping for efficacy. For estimation of efficacy at a second, extended, follow-up time, the performance of a shrinkage estimator (SHE), a probability tree estimator (PTE) and the maximum likelihood estimator (MLE) for estimation was assessed by simulation. The SHE and PTE are viable approaches to estimate an extended follow-up although the SHE performed better than the PTE: the bias and root mean square error were lower and coverage probabilities higher. Generalization of the triangular design is simple to implement for adaptations to meet requirements for pharmacokinetic analyses. Using the simple MLE approach to estimate efficacy at extended follow-up will lead to biased results, generally over-estimating treatment success. The SHE is recommended in trials of two or more treatments. The PTE is an acceptable alternative for one-arm trials or where use of the SHE is not possible due to computational complexity. NCT01067443 , February 2010.

Hierarchically triangular prism structured Co3O4: Self-supported fabrication and photocatalytic property

EPA Science Inventory

The formation of ammonium cobalt (II) phosphate was utilized to synthesize unprecedented 3D structures of Co3O4, triangular prisms and trunk-like structures, via a self-supported and organics-free method. The length of a triangular side of the prepared 3D triangular prisms is ~1...

Static and dynamical properties of the spin-1/2 equilateral triangular-lattice antiferromagnet Ba 3CoSb 2O 9

DOE PAGES

Ma, Jie; Kamiya, Yoshitomo; Hong, Tao; ...

2016-02-24

We present single-crystal neutron scattering measurements of the spin-1/2 equilateral triangular-lattice antiferromagnet Ba 3CoSb 2O 9. Besides confirming that the Co 2+ magnetic moments lie in the ab plane for zero magnetic field and then determining all the exchange parameters of the minimal quasi-2D spin Hamiltonian, we provide conclusive experimental evidence of magnon decay through observation of intrinsic line broadening. Through detailed comparisons with the linear and nonlinear spin-wave theories, we also point out that the large-S approximation, which is conventionally employed to predict magnon decay in noncollinear magnets, is inadequate to explain our experimental observation. Hence, our results callmore » for a new theoretical framework for describing excitation spectra in low-dimensional frustrated magnets under strong quantum effects.« less

An adaptive optics package designed for astronomical use with a laser guide star tuned to an absorption line of atomic sodium

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

Salmon, J.T.; Avicola, K.; Brase, J.M.

1994-04-11

We present the design and implementation of a very compact adaptive optic system that senses the return light from a sodium guide-star and controls a deformable mirror and a pointing mirror to compensate atmospheric perturbations in the wavefront. The deformable mirror has 19 electrostrictive actuators and triangular subapertures. The wavefront sensor is a Hartmann sensor with lenslets on triangular centers. The high-bandwidth steering mirror assembly incorporates an analog controller that samples the tilt with an avalanche photodiode quad cell. An {line_integral}/25 imaging leg focuses the light into a science camera that can either obtain long-exposure images or speckle data. Inmore » laboratory tests overall Strehl ratios were improved by a factor of 3 when a mylar sheet was used as an aberrator. The crossover frequency at unity gain is 30 Hz.« less

Bell inequalities stronger than the Clauser-Horne-Shimony-Holt inequality for three-level isotropic states

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

Ito, Tsuyoshi; Imai, Hiroshi; ERATO-SORST Quantum Computation and Information Project, Japan Science and Technology Agency, 5-28-3 Hongo, Bunkyo-ku, Tokyo, 113-0033

2006-04-15

We show that some two-party Bell inequalities with two-valued observables are stronger than the CHSH inequality for 3x3 isotropic states in the sense that they are violated by some isotropic states in the 3x3 system that do not violate the CHSH inequality. These Bell inequalities are obtained by applying triangular elimination to the list of known facet inequalities of the cut polytope on nine points. This gives a partial solution to an open problem posed by Collins and Gisin. The results of numerical optimization suggest that they are candidates for being stronger than the I{sub 3322} Bell inequality for 3x3more » isotropic states. On the other hand, we found no Bell inequalities stronger than the CHSH inequality for 2x2 isotropic states. In addition, we illustrate an inclusion relation among some Bell inequalities derived by triangular elimination.« less

Pointwise convergence of derivatives of Lagrange interpolation polynomials for exponential weights

NASA Astrophysics Data System (ADS)

Damelin, S. B.; Jung, H. S.

2005-01-01

For a general class of exponential weights on the line and on (-1,1), we study pointwise convergence of the derivatives of Lagrange interpolation. Our weights include even weights of smooth polynomial decay near +/-[infinity] (Freud weights), even weights of faster than smooth polynomial decay near +/-[infinity] (Erdos weights) and even weights which vanish strongly near +/-1, for example Pollaczek type weights.

Implicit Contractive Mappings in Modular Metric and Fuzzy Metric Spaces

PubMed Central

Hussain, N.; Salimi, P.

2014-01-01

The notion of modular metric spaces being a natural generalization of classical modulars over linear spaces like Lebesgue, Orlicz, Musielak-Orlicz, Lorentz, Orlicz-Lorentz, and Calderon-Lozanovskii spaces was recently introduced. In this paper we investigate the existence of fixed points of generalized α-admissible modular contractive mappings in modular metric spaces. As applications, we derive some new fixed point theorems in partially ordered modular metric spaces, Suzuki type fixed point theorems in modular metric spaces and new fixed point theorems for integral contractions. In last section, we develop an important relation between fuzzy metric and modular metric and deduce certain new fixed point results in triangular fuzzy metric spaces. Moreover, some examples are provided here to illustrate the usability of the obtained results. PMID:25003157

Materials trade study for lunar/gateway missions.

PubMed

Tripathi, R K; Wilson, J W; Cucinotta, F A; Anderson, B M; Simonsen, L C

2003-01-01

The National Aeronautics and Space Administration (NASA) administrator has identified protection from radiation hazards as one of the two biggest problems of the agency with respect to human deep space missions. The intensity and strength of cosmic radiation in deep space makes this a 'must solve' problem for space missions. The Moon and two Earth-Moon Lagrange points near Moon are being proposed as hubs for deep space missions. The focus of this study is to identify approaches to protecting astronauts and habitats from adverse effects from space radiation both for single missions and multiple missions for career astronauts to these destinations. As the great cost of added radiation shielding is a potential limiting factor in deep space missions, reduction of mass, without compromising safety, is of paramount importance. The choice of material and selection of the crew profile play major roles in design and mission operations. Material trade studies in shield design over multi-segmented missions involving multiple work and living areas in the transport and duty phase of space mission's to two Earth-Moon co-linear Lagrange points (L1) between Earth and the Moon and (L2) on back side of the moon as seen from Earth, and to the Moon have been studied. It is found that, for single missions, current state-of-the-art knowledge of material provides adequate shielding. On the other hand, the choice of shield material is absolutely critical for career astronauts and revolutionary materials need to be developed for these missions. This study also provides a guide to the effectiveness of multifunctional materials in preparation for more detailed geometry studies in progress. c2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

Feasibility of cooling the Earth with a cloud of small spacecraft near the inner Lagrange point (L1).

PubMed

Angel, Roger

2006-11-14

If it were to become apparent that dangerous changes in global climate were inevitable, despite greenhouse gas controls, active methods to cool the Earth on an emergency basis might be desirable. The concept considered here is to block 1.8% of the solar flux with a space sunshade orbited near the inner Lagrange point (L1), in-line between the Earth and sun. Following the work of J. Early [Early, JT (1989) J Br Interplanet Soc 42:567-569], transparent material would be used to deflect the sunlight, rather than to absorb it, to minimize the shift in balance out from L1 caused by radiation pressure. Three advances aimed at practical implementation are presented. First is an optical design for a very thin refractive screen with low reflectivity, leading to a total sunshade mass of approximately 20 million tons. Second is a concept aimed at reducing transportation cost to 50 dollars/kg by using electromagnetic acceleration to escape Earth's gravity, followed by ion propulsion. Third is an implementation of the sunshade as a cloud of many spacecraft, autonomously stabilized by modulating solar radiation pressure. These meter-sized "flyers" would be assembled completely before launch, avoiding any need for construction or unfolding in space. They would weigh a gram each, be launched in stacks of 800,000, and remain for a projected lifetime of 50 years within a 100,000-km-long cloud. The concept builds on existing technologies. It seems feasible that it could be developed and deployed in approximately 25 years at a cost of a few trillion dollars, <0.5% of world gross domestic product (GDP) over that time.

Feasibility of cooling the Earth with a cloud of small spacecraft near the inner Lagrange point (L1)

PubMed Central

Angel, Roger

2006-01-01

If it were to become apparent that dangerous changes in global climate were inevitable, despite greenhouse gas controls, active methods to cool the Earth on an emergency basis might be desirable. The concept considered here is to block 1.8% of the solar flux with a space sunshade orbited near the inner Lagrange point (L1), in-line between the Earth and sun. Following the work of J. Early [Early, JT (1989) J Br Interplanet Soc 42:567–569], transparent material would be used to deflect the sunlight, rather than to absorb it, to minimize the shift in balance out from L1 caused by radiation pressure. Three advances aimed at practical implementation are presented. First is an optical design for a very thin refractive screen with low reflectivity, leading to a total sunshade mass of ≈20 million tons. Second is a concept aimed at reducing transportation cost to $50/kg by using electromagnetic acceleration to escape Earth's gravity, followed by ion propulsion. Third is an implementation of the sunshade as a cloud of many spacecraft, autonomously stabilized by modulating solar radiation pressure. These meter-sized “flyers” would be assembled completely before launch, avoiding any need for construction or unfolding in space. They would weigh a gram each, be launched in stacks of 800,000, and remain for a projected lifetime of 50 years within a 100,000-km-long cloud. The concept builds on existing technologies. It seems feasible that it could be developed and deployed in ≈25 years at a cost of a few trillion dollars, <0.5% of world gross domestic product (GDP) over that time. PMID:17085589

ACOSS Eleven (Active Control of Space Structures). Volume 1

DTIC Science & Technology

1983-12-01

Influence Function ................. 19 3.4 Mirror Deformations. ........................... o............. 23 3.5 Selection of Point Objects...to simulate errors in the knowledge of influence function . 5) The influence function for edge actuators may be different from that for interior... Influence Function Each of the three mirrors has 37 actuators distributed on an equi- lateral triangular lattice as shown in Figure 3-3. In consultation with

Extended hamiltonian formalism and Lorentz-violating lagrangians

NASA Astrophysics Data System (ADS)

Colladay, Don

2017-09-01

A new perspective on the classical mechanical formulation of particle trajectories in Lorentz-violating theories is presented. Using the extended hamiltonian formalism, a Legendre Transformation between the associated covariant lagrangian and hamiltonian varieties is constructed. This approach enables calculation of trajectories using Hamilton's equations in momentum space and the Euler-Lagrange equations in velocity space away from certain singular points that arise in the theory. Singular points are naturally de-singularized by requiring the trajectories to be smooth functions of both velocity and momentum variables. In addition, it is possible to identify specific sheets of the dispersion relations that correspond to specific solutions for the lagrangian. Examples corresponding to bipartite Finsler functions are computed in detail. A direct connection between the lagrangians and the field-theoretic solutions to the Dirac equation is also established for a special case.

Transition from the mechanics of material points to the mechanics of structured particles

NASA Astrophysics Data System (ADS)

Somsikov, V. M.

2016-01-01

In this paper, necessity of creation of mechanics of structured particles is discussed. The way to create this mechanics within the laws of classical mechanics with the use of energy equation is shown. The occurrence of breaking of time symmetry within the mechanics of structured particles is shown, as well as the introduction of concept of entropy in the framework of classical mechanics. The way to create the mechanics of non-equilibrium systems in the thermodynamic approach is shown. It is also shown that the use of hypothesis of holonomic constraints while deriving the canonical Lagrange equation made it impossible to describe irreversible dynamics. The difference between the mechanics of structured particles and the mechanics of material points is discussed. It is also shown that the matter is infinitely divisible according to the laws of classical mechanics.

The correlation of initial radiographic characteristics of distal radius fractures and injuries of the triangular fibrocartilage complex.

PubMed

Kasapinova, K; Kamiloski, V

2016-06-01

Our purpose was to determine the correlation of initial radiographic parameters of a distal radius fracture with an injury of the triangular fibrocartilage complex. In a prospective study, 85 patients with surgically treated distal radius fractures were included. Wrist arthroscopy was used to identify and classify triangular fibrocartilage complex lesions. The initial radial length and angulation, dorsal angulation, ulnar variance and distal radioulnar distance were measured. Wrist arthroscopy identified a triangular fibrocartilage complex lesion in 45 patients. Statistical analysis did not identify a correlation with any single radiographic parameter of the distal radius fractures with the associated triangular fibrocartilage complex injuries. The initial radiograph of a distal radius fracture does not predict a triangular fibrocartilage complex injury. III. © The Author(s) 2016.

Hesitant triangular fuzzy information aggregation operators based on Bonferroni means and their application to multiple attribute decision making.

PubMed

Wang, Chunyong; Li, Qingguo; Zhou, Xiaoqiang; Yang, Tian

2014-01-01

We investigate the multiple attribute decision-making (MADM) problems with hesitant triangular fuzzy information. Firstly, definition and some operational laws of hesitant triangular fuzzy elements are introduced. Then, we develop some hesitant triangular fuzzy aggregation operators based on Bonferroni means and discuss their basic properties. Some existing operators can be viewed as their special cases. Next, we apply the proposed operators to deal with multiple attribute decision-making problems under hesitant triangular fuzzy environment. Finally, an illustrative example is given to show the developed method and demonstrate its practicality and effectiveness.

Hesitant Triangular Fuzzy Information Aggregation Operators Based on Bonferroni Means and Their Application to Multiple Attribute Decision Making

PubMed Central

Zhou, Xiaoqiang; Yang, Tian

2014-01-01

We investigate the multiple attribute decision-making (MADM) problems with hesitant triangular fuzzy information. Firstly, definition and some operational laws of hesitant triangular fuzzy elements are introduced. Then, we develop some hesitant triangular fuzzy aggregation operators based on Bonferroni means and discuss their basic properties. Some existing operators can be viewed as their special cases. Next, we apply the proposed operators to deal with multiple attribute decision-making problems under hesitant triangular fuzzy environment. Finally, an illustrative example is given to show the developed method and demonstrate its practicality and effectiveness. PMID:25140338

Series of Reciprocal Triangular Numbers

ERIC Educational Resources Information Center

Bruckman, Paul; Dence, Joseph B.; Dence, Thomas P.; Young, Justin

2013-01-01

Reciprocal triangular numbers have appeared in series since the very first infinite series were summed. Here we attack a number of subseries of the reciprocal triangular numbers by methodically expressing them as integrals.

A Generalization of the Formula for the Triangular Number of the Sum and Product of Natural Numbers

ERIC Educational Resources Information Center

Asiru, M. A.

2008-01-01

This note generalizes the formula for the triangular number of the sum and product of two natural numbers to similar results for the triangular number of the sum and product of "r" natural numbers. The formula is applied to derive formula for the sum of an odd and an even number of consecutive triangular numbers.

Biostereometric Data Processing In ERGODATA: Choice Of Human Body Models

NASA Astrophysics Data System (ADS)

Pineau, J. C.; Mollard, R.; Sauvignon, M.; Amphoux, M.

1983-07-01

The definition of human body models was elaborated with anthropometric data from ERGODATA. The first model reduces the human body into a series of points and lines. The second model is well adapted to represent volumes of each segmentary element. The third is an original model built from the conventional anatomical points. Each segment is defined in space by a tri-angular plane located with its 3-D coordinates. This new model can answer all the processing possibilities in the field of computer-aided design (C.A.D.) in ergonomy but also biomechanics and orthopaedics.

Acoustic response of a rectangular levitator with orifices

NASA Technical Reports Server (NTRS)

El-Raheb, Michael; Wagner, Paul

1990-01-01

The acoustic response of a rectangular cavity to speaker-generated excitation through waveguides terminating at orifices in the cavity walls is analyzed. To find the effects of orifices, acoustic pressure is expressed by eigenfunctions satisfying Neumann boundary conditions as well as by those satisfying Dirichlet ones. Some of the excess unknowns can be eliminated by point constraints set over the boundary, by appeal to Lagrange undetermined multipliers. The resulting transfer matrix must be further reduced by partial condensation to the order of a matrix describing unmixed boundary conditions. If the cavity is subjected to an axial temperature dependence, the transfer matrix is determined numerically.

The Impact of Discontinuity Front Orientation on the Accuracy of L1 Space Weather Forecasting

NASA Astrophysics Data System (ADS)

Szabo, A.

2013-12-01

Current space weather forecasting from the Sun-Earth first Lagrange (L1) point assumes that all observed solar wind discontinuity fronts (interplanetary shocks, ICME boundaries) are perpendicular to the Sun-Earth line and are propagating radially out from eh Sun. In reality, these weather fronts can have significantly tilted orientation. Combined ACE, Wind and Soho observations allow the quantification of this effect. With the launch of the DSCOVR spacecraft in early 2015, dual real-time solar wind measurements will become available (at least at some time). Algorithms and their impact exploiting this unique scenario will be discussed.

The James Webb Space Telescope

NASA Technical Reports Server (NTRS)

Mather, John C.

2003-01-01

The James Webb Space Telescope (JWST) will extend the discoveries of the Hubble Space Telescope by deploying a large cooled infrared telescope at the Sun-Earth Lagrange point L2. With a 6 m aperture and three instruments covering the wavelength range from 0.6 to 28 pm, it will provide sensitivities orders of magnitude better than any other facilities. It is intended to observe the light from the first galaxies and the first supernovae, the assembly of galaxies, and the formation and evolution of stars and planetary systems. In this talk I will review the scientific objectives, the hardware concepts and technology, and the predicted system performance.

The James Webb Space Telscope

NASA Technical Reports Server (NTRS)

Mather, John C.

2003-01-01

The James Webb Space Telescope (JWST) will extend the discoveries of the Hubble Space Telescope by deploying a large cooled infrared telescope at the Sun-Earth Lagrange point L2. With a 6 m aperture and three instruments covering the wavelength range from 0.6 to 28 microns, it will provide sensitivities orders of magnitude better than any other facilities. It is intended to observe the light from the first galaxies and the first supernovae, the assembly of galaxies, and the formation and evolution of stars and planetary systems. In this talk I will review the scientific objectives, the hardware concepts and technology, and the predicted system performance.

PID position regulation in one-degree-of-freedom Euler-Lagrange systems actuated by a PMSM

NASA Astrophysics Data System (ADS)

Verastegui-Galván, J.; Hernández-Guzmán, V. M.; Orrante-Sakanassi, J.

2018-02-01

This paper is concerned with position regulation in one-degree-of-freedom Euler-Lagrange Systems. We consider that the mechanical subsystem is actuated by a permanent magnet synchronous motor (PMSM). Our proposal consists of a Proportional-Integral-Derivative (PID) controller for the mechanical subsystem and a slight variation of field oriented control for the PMSM. We take into account the motor electric dynamics during the stability analysis. We present, for the first time, a global asymptotic stability proof for such a control scheme without requiring the mechanical subsystem to naturally possess viscous friction. Finally, as a corollary of our main result we prove global asymptotic stability for output feedback PID regulation of one-degree-of-freedom Euler-Lagrange systems when generated torque is considered as the system input, i.e. when the electric dynamics of PMSM's is not taken into account.

Application of parallel distributed Lagrange multiplier technique to simulate coupled Fluid-Granular flows in pipes with varying Cross-Sectional area

DOE PAGES

Kanarska, Yuliya; Walton, Otis

2015-11-30

Fluid-granular flows are common phenomena in nature and industry. Here, an efficient computational technique based on the distributed Lagrange multiplier method is utilized to simulate complex fluid-granular flows. Each particle is explicitly resolved on an Eulerian grid as a separate domain, using solid volume fractions. The fluid equations are solved through the entire computational domain, however, Lagrange multiplier constrains are applied inside the particle domain such that the fluid within any volume associated with a solid particle moves as an incompressible rigid body. The particle–particle interactions are implemented using explicit force-displacement interactions for frictional inelastic particles similar to the DEMmore » method with some modifications using the volume of an overlapping region as an input to the contact forces. Here, a parallel implementation of the method is based on the SAMRAI (Structured Adaptive Mesh Refinement Application Infrastructure) library.« less

Modeling of Mixing Behavior in a Combined Blowing Steelmaking Converter with a Filter-Based Euler-Lagrange Model

NASA Astrophysics Data System (ADS)

Li, Mingming; Li, Lin; Li, Qiang; Zou, Zongshu

2018-05-01

A filter-based Euler-Lagrange multiphase flow model is used to study the mixing behavior in a combined blowing steelmaking converter. The Euler-based volume of fluid approach is employed to simulate the top blowing, while the Lagrange-based discrete phase model that embeds the local volume change of rising bubbles for the bottom blowing. A filter-based turbulence method based on the local meshing resolution is proposed aiming to improve the modeling of turbulent eddy viscosities. The model validity is verified through comparison with physical experiments in terms of mixing curves and mixing times. The effects of the bottom gas flow rate on bath flow and mixing behavior are investigated and the inherent reasons for the mixing result are clarified in terms of the characteristics of bottom-blowing plumes, the interaction between plumes and top-blowing jets, and the change of bath flow structure.

Life History and Environmental Requirements of Loggerhead Turtles

DTIC Science & Technology

1988-08-01

NOMENCLATURE/TAXONOMY/RANGE Scientific name ........ .................... Caretta caretta Preferred common name ........ ................. Loggerhead...Green 51-105 113-140 Broad, oval Olive , dark- White- Small round 15(90)’ (100)a brown mottled yellowish Loggerhead 79-125 77-140 Heart-shaped Reddish...Cream- Very large 25 (110)8 (105)8 brown yellow triangular Kemp’s ridey 59-73 36-45 Circular Olive -green Yellow Medium 13 (70)a (42)’ pointed

An interactive display system for large-scale 3D models

NASA Astrophysics Data System (ADS)

Liu, Zijian; Sun, Kun; Tao, Wenbing; Liu, Liman

2018-04-01

With the improvement of 3D reconstruction theory and the rapid development of computer hardware technology, the reconstructed 3D models are enlarging in scale and increasing in complexity. Models with tens of thousands of 3D points or triangular meshes are common in practical applications. Due to storage and computing power limitation, it is difficult to achieve real-time display and interaction with large scale 3D models for some common 3D display software, such as MeshLab. In this paper, we propose a display system for large-scale 3D scene models. We construct the LOD (Levels of Detail) model of the reconstructed 3D scene in advance, and then use an out-of-core view-dependent multi-resolution rendering scheme to realize the real-time display of the large-scale 3D model. With the proposed method, our display system is able to render in real time while roaming in the reconstructed scene and 3D camera poses can also be displayed. Furthermore, the memory consumption can be significantly decreased via internal and external memory exchange mechanism, so that it is possible to display a large scale reconstructed scene with over millions of 3D points or triangular meshes in a regular PC with only 4GB RAM.

Ordering phenomena in a heterostructure of frustrated and unfrustrated triangular-lattice Ising layers

NASA Astrophysics Data System (ADS)

Žukovič, Milan; Tomita, Yusuke; Kamiya, Y.

2017-07-01

We study critical and magnetic properties of a bilayer Ising system consisting of two triangular planes A and B, with the antiferromagnetic (AF) coupling JA and the ferromagnetic (FM) one JB for the respective layers, which are coupled by the interlayer interaction JAB by using Monte Carlo simulations. When JA and JB are of the same order, the unfrustrated FM plane orders first at a high temperature Tc 1˜JB . The spontaneous FM order then exerts influence on the other frustrated AF plane as an effective magnetic field, which subsequently induces a ferrimagnetic order in this plane at low temperatures below Tc 2. When short-range order is developed in the AF plane while the influence of the FM plane is still small, there appears a preemptive Berezinskii-Kosterlitz-Thouless-type pseudocritical crossover regime just above the ferrimagnetic phase transition point, where the short-distance behavior up to a rather large length scale exponentially diverging in ∝JA/T is controlled by a line of Gaussian fixed points at T =0 . In the crossover region, a continuous variation in the effective critical exponent 4/9 ≲ηeff≲1/2 is observed. The phase diagram by changing the ratio JA/JB is also investigated.

Methodologies for Development of Patient Specific Bone Models from Human Body CT Scans

NASA Astrophysics Data System (ADS)

Chougule, Vikas Narayan; Mulay, Arati Vinayak; Ahuja, Bharatkumar Bhagatraj

2016-06-01

This work deals with development of algorithm for physical replication of patient specific human bone and construction of corresponding implants/inserts RP models by using Reverse Engineering approach from non-invasive medical images for surgical purpose. In medical field, the volumetric data i.e. voxel and triangular facet based models are primarily used for bio-modelling and visualization, which requires huge memory space. On the other side, recent advances in Computer Aided Design (CAD) technology provides additional facilities/functions for design, prototyping and manufacturing of any object having freeform surfaces based on boundary representation techniques. This work presents a process to physical replication of 3D rapid prototyping (RP) physical models of human bone from various CAD modeling techniques developed by using 3D point cloud data which is obtained from non-invasive CT/MRI scans in DICOM 3.0 format. This point cloud data is used for construction of 3D CAD model by fitting B-spline curves through these points and then fitting surface between these curve networks by using swept blend techniques. This process also can be achieved by generating the triangular mesh directly from 3D point cloud data without developing any surface model using any commercial CAD software. The generated STL file from 3D point cloud data is used as a basic input for RP process. The Delaunay tetrahedralization approach is used to process the 3D point cloud data to obtain STL file. CT scan data of Metacarpus (human bone) is used as the case study for the generation of the 3D RP model. A 3D physical model of the human bone is generated on rapid prototyping machine and its virtual reality model is presented for visualization. The generated CAD model by different techniques is compared for the accuracy and reliability. The results of this research work are assessed for clinical reliability in replication of human bone in medical field.

Mathematical model of parking space unit for triangular parking area

NASA Astrophysics Data System (ADS)

Syahrini, Intan; Sundari, Teti; Iskandar, Taufiq; Halfiani, Vera; Munzir, Said; Ramli, Marwan

2018-01-01

Parking space unit (PSU) is an effective measure for the area size of a vehicle, including the free space and the width of the door opening of the vehicle (car). This article discusses a mathematical model for parking space of vehicles in triangular shape area. An optimization model for triangular parking lot is developed. Integer Linear Programming (ILP) method is used to determine the maximum number of the PSU. The triangular parking lot is in isosceles and equilateral triangles shape and implements four possible rows and five possible angles for each field. The vehicles which are considered are cars and motorcycles. The results show that the isosceles triangular parking area has 218 units of optimal PSU, which are 84 units of PSU for cars and 134 units of PSU for motorcycles. Equilateral triangular parking area has 688 units of optimal PSU, which are 175 units of PSU for cars and 513 units of PSU for motorcycles.

A Novel Multi-Receiver Signcryption Scheme with Complete Anonymity.

PubMed

Pang, Liaojun; Yan, Xuxia; Zhao, Huiyang; Hu, Yufei; Li, Huixian

2016-01-01

Anonymity, which is more and more important to multi-receiver schemes, has been taken into consideration by many researchers recently. To protect the receiver anonymity, in 2010, the first multi-receiver scheme based on the Lagrange interpolating polynomial was proposed. To ensure the sender's anonymity, the concept of the ring signature was proposed in 2005, but afterwards, this scheme was proven to has some weakness and at the same time, a completely anonymous multi-receiver signcryption scheme is proposed. In this completely anonymous scheme, the sender anonymity is achieved by improving the ring signature, and the receiver anonymity is achieved by also using the Lagrange interpolating polynomial. Unfortunately, the Lagrange interpolation method was proven a failure to protect the anonymity of receivers, because each authorized receiver could judge whether anyone else is authorized or not. Therefore, the completely anonymous multi-receiver signcryption mentioned above can only protect the sender anonymity. In this paper, we propose a new completely anonymous multi-receiver signcryption scheme with a new polynomial technology used to replace the Lagrange interpolating polynomial, which can mix the identity information of receivers to save it as a ciphertext element and prevent the authorized receivers from verifying others. With the receiver anonymity, the proposed scheme also owns the anonymity of the sender at the same time. Meanwhile, the decryption fairness and public verification are also provided.

The triangular kagomé lattices revisited

NASA Astrophysics Data System (ADS)

Liu, Xiaoyun; Yan, Weigen

2013-11-01

The dimer problem, Ising spins and bond percolation on the triangular kagomé lattice have been studied extensively by physicists. In this paper, based on the fact the triangular kagomé lattice with toroidal boundary condition can be regarded as the line graph of 3.12.12 lattice with toroidal boundary condition, we derive the formulae of the number of spanning trees, the energy, and the Kirchhoff index of the triangular kagomé lattice with toroidal boundary condition.

Classification of ulnar triangular fibrocartilage complex tears. A treatment algorithm for Palmer type IB tears.

PubMed

Atzei, A; Luchetti, R; Garagnani, L

2017-05-01

The classical definition of 'Palmer Type IB' triangular fibrocartilage complex tear, includes a spectrum of clinical conditions. This review highlights the clinical and arthroscopic criteria that enable us to categorize five classes on a treatment-oriented classification system of triangular fibrocartilage complex peripheral tears. Class 1 lesions represent isolated tears of the distal triangular fibrocartilage complex without distal radio-ulnar joint instability and are amenable to arthroscopic suture. Class 2 tears include rupture of both the distal triangular fibrocartilage complex and proximal attachments of the triangular fibrocartilage complex to the fovea. Class 3 tears constitute isolated ruptures of the proximal attachment of the triangular fibrocartilage complex to the fovea; they are not visible at radio-carpal arthroscopy. Both Class 2 and Class 3 tears are diagnosed with a positive hook test and are typically associated with distal radio-ulnar joint instability. If required, treatment is through reattachment of the distal radio-ulnar ligament insertions to the fovea. Class 4 lesions are irreparable tears due to the size of the defect or to poor tissue quality and, if required, treatment is through distal radio-ulnar ligament reconstruction with tendon graft. Class 5 tears are associated with distal radio-ulnar joint arthritis and can only be treated with salvage procedures. This subdivision of type IB triangular fibrocartilage complex tear provides more insights in the pathomechanics and treatment strategies. II.

A novel method of the image processing on irregular triangular meshes

NASA Astrophysics Data System (ADS)

Vishnyakov, Sergey; Pekhterev, Vitaliy; Sokolova, Elizaveta

2018-04-01

The paper describes a novel method of the image processing based on irregular triangular meshes implementation. The triangular mesh is adaptive to the image content, least mean square linear approximation is proposed for the basic interpolation within the triangle. It is proposed to use triangular numbers to simplify using of the local (barycentric) coordinates for the further analysis - triangular element of the initial irregular mesh is to be represented through the set of the four equilateral triangles. This allows to use fast and simple pixels indexing in local coordinates, e.g. "for" or "while" loops for access to the pixels. Moreover, representation proposed allows to use discrete cosine transform of the simple "rectangular" symmetric form without additional pixels reordering (as it is used for shape-adaptive DCT forms). Furthermore, this approach leads to the simple form of the wavelet transform on triangular mesh. The results of the method application are presented. It is shown that advantage of the method proposed is a combination of the flexibility of the image-adaptive irregular meshes with the simple form of the pixel indexing in local triangular coordinates and the using of the common forms of the discrete transforms for triangular meshes. Method described is proposed for the image compression, pattern recognition, image quality improvement, image search and indexing. It also may be used as a part of video coding (intra-frame or inter-frame coding, motion detection).

Uncertainty propagation in the calibration equations for NTC thermistors

NASA Astrophysics Data System (ADS)

Liu, Guang; Guo, Liang; Liu, Chunlong; Wu, Qingwen

2018-06-01

The uncertainty propagation problem is quite important for temperature measurements, since we rely so much on the sensors and calibration equations. Although uncertainty propagation for platinum resistance or radiation thermometers is well known, there have been few publications concerning negative temperature coefficient (NTC) thermistors. Insight into the propagation characteristics of uncertainty that develop when equations are determined using the Lagrange interpolation or least-squares fitting method is presented here with respect to several of the most common equations used in NTC thermistor calibration. Within this work, analytical expressions of the propagated uncertainties for both fitting methods are derived for the uncertainties in the measured temperature and resistance at each calibration point. High-precision calibration of an NTC thermistor in a precision water bath was performed by means of the comparison method. Results show that, for both fitting methods, the propagated uncertainty is flat in the interpolation region but rises rapidly beyond the calibration range. Also, for temperatures interpolated between calibration points, the propagated uncertainty is generally no greater than that associated with the calibration points. For least-squares fitting, the propagated uncertainty is significantly reduced by increasing the number of calibration points and can be well kept below the uncertainty of the calibration points.

A Direct Method for Fuel Optimal Maneuvers of Distributed Spacecraft in Multiple Flight Regimes

NASA Technical Reports Server (NTRS)

Hughes, Steven P.; Cooley, D. S.; Guzman, Jose J.

2005-01-01

We present a method to solve the impulsive minimum fuel maneuver problem for a distributed set of spacecraft. We develop the method assuming a non-linear dynamics model and parameterize the problem to allow the method to be applicable to multiple flight regimes including low-Earth orbits, highly-elliptic orbits (HEO), Lagrange point orbits, and interplanetary trajectories. Furthermore, the approach is not limited by the inter-spacecraft separation distances and is applicable to both small formations as well as large constellations. Semianalytical derivatives are derived for the changes in the total AV with respect to changes in the independent variables. We also apply a set of constraints to ensure that the fuel expenditure is equalized over the spacecraft in formation. We conclude with several examples and present optimal maneuver sequences for both a HE0 and libration point formation.

Pairwise Interaction Extended Point-Particle (PIEP) model for multiphase jets and sedimenting particles

NASA Astrophysics Data System (ADS)

Liu, Kai; Balachandar, S.

2017-11-01

We perform a series of Euler-Lagrange direct numerical simulations (DNS) for multiphase jets and sedimenting particles. The forces the flow exerts on the particles in these two-way coupled simulations are computed using the Basset-Bousinesq-Oseen (BBO) equations. These forces do not explicitly account for particle-particle interactions, even though such pairwise interactions induced by the perturbations from neighboring particles may be important especially when the particle volume fraction is high. Such effects have been largely unaddressed in the literature. Here, we implement the Pairwise Interaction Extended Point-Particle (PIEP) model to simulate the effect of neighboring particle pairs. A simple collision model is also applied to avoid unphysical overlapping of solid spherical particles. The simulation results indicate that the PIEP model provides a more elaborative and complicated movement of the dispersed phase (droplets and particles). Office of Naval Research (ONR) Multidisciplinary University Research Initiative (MURI) project N00014-16-1-2617.

Spectroscopic properties of triangular silver nanoplates immobilized on polyelectrolyte multilayer-modified glass substrates

NASA Astrophysics Data System (ADS)

Rabor, Janice B.; Kawamura, Koki; Muko, Daiki; Kurawaki, Junichi; Niidome, Yasuro

2017-07-01

Fabrication of surface-immobilized silver nanostructures with reproducible plasmonic properties by dip-coating technique is difficult due to shape alteration. To address this challenge, we used a polyelectrolyte multilayer to promote immobilization of as-received triangular silver nanoplates (TSNP) on a glass substrate through electrostatic interaction. The substrate-immobilized TSNP were characterized by absorption spectrophotometry and scanning electron microscopy. The bandwidth and peak position of localized surface plasmon resonance (LSPR) bands can be tuned by simply varying the concentration of the colloidal solution and immersion time. TSNP immobilized from a higher concentration of colloidal solution with longer immersion time produced broadened LSPR bands in the near-IR region, while a lower concentration with shorter immersion time produced narrower bands in the visible region. The shape of the nanoplates was retained even at long immersion time. Analysis of peak positions and bandwidths also revealed the point at which the main species of the immobilization had been changed from isolates to aggregates.

Fall Down Detection Under Smart Home System.

PubMed

Juang, Li-Hong; Wu, Ming-Ni

2015-10-01

Medical technology makes an inevitable trend for the elderly population, therefore the intelligent home care is an important direction for science and technology development, in particular, elderly in-home safety management issues become more and more important. In this research, a low of operation algorithm and using the triangular pattern rule are proposed, then can quickly detect fall-down movements of humanoid by the installation of a robot with camera vision at home that will be able to judge the fall-down movements of in-home elderly people in real time. In this paper, it will present a preliminary design and experimental results of fall-down movements from body posture that utilizes image pre-processing and three triangular-mass-central points to extract the characteristics. The result shows that the proposed method would adopt some characteristic value and the accuracy can reach up to 90 % for a single character posture. Furthermore the accuracy can be up to 100 % when a continuous-time sampling criterion and support vector machine (SVM) classifier are used.

The Effect of a Soap Film on a Catenary: Measurement of Surface Tension from the Triangular Configuration

ERIC Educational Resources Information Center

Behroozi, F.; Behroozi, P. S.

2011-01-01

A chain assumes the well-known shape known as a catenary when it hangs loosely from two points in a gravitational field. The correct solution of the catenary was one of the early triumphs of the newly invented calculus of variations at the end of the 17th century. Here we revisit the catenary and show that, for a chain hanging from a horizontal…

Characterization of Martian Rock Shape for MER Airbag Drop Tests

NASA Astrophysics Data System (ADS)

Dimaggio, E. N.; Schroeder, R.; Castle, N.; Golombek, M.

2002-12-01

Rock distributions for the final platforms used in airbag drop tests are currently being designed for the Mars Exploration Rovers (MER) scheduled to launch in 2003. Like Mars Pathfinder (MPF), launched in 1996, MER will use a series of airbags to cushion its landing on the surface of Mars. Previous MER airbag drop tests have shown that sharp, angular (triangular) rocks >20 cm high may be hazardous. To aid in defining the rock distributions for the final airbag tests, images from the Viking Landers 1 and 2 and MPF were used to identify rocks that are >20 cm high, and characterize them as triangular, square or round. Approximately 33% of all rocks analyzed are triangular. Of the rocks analyzed that are ~20-60 cm high, ~14% are triangular. Most of these triangular rocks are small, ~20-30 cm high. Rock distributions of previous airbag platforms were similarly classified and show a greater percentage of triangular and square rocks that are ~20-60 cm high than at the landing sites. The burial of a rock (perched, partially buried or buried) was also considered because perched rocks may pose less of a threat to the airbags than those buried because perched rocks can be dislodged and roll during impact. Approximately 19% of all rocks analyzed, and ~19% of rocks that are ~20-60 cm high, are triangular and partially buried or buried. These data suggest that the platform rock distributions appropriately represented the risks to the airbags associated with triangular rocks. A similar percentage of >20 cm high triangular rocks will be added to the drop test platforms to represent landing site rock distributions.

The Relation Among the Likelihood Ratio-, Wald-, and Lagrange Multiplier Tests and Their Applicability to Small Samples,

DTIC Science & Technology

1982-04-01

S. (1979), "Conflict Among Criteria for Testing Hypothesis: Extension and Comments," Econometrica, 47, 203-207 Breusch , T. S. and Pagan , A. R. (1980...Savin, N. E. (1977), "Conflict Among Criteria for Testing Hypothesis in the Multivariate Linear Regression Model," Econometrica, 45, 1263-1278 Breusch , T...VNCLASSIFIED RAND//-6756NL U l~ I- THE RELATION AMONG THE LIKELIHOOD RATIO-, WALD-, AND LAGRANGE MULTIPLIER TESTS AND THEIR APPLICABILITY TO SMALL SAMPLES

Subscale Fast Cookoff Testing and Modeling for the Hazard Assessment of Large Rocket Motors

DTIC Science & Technology

2001-03-01

41 LIST OF TABLES Table 1 Heats of Vaporization Parameter for Two-liner Phase Transformation - Complete Liner Sublimation and/or Combined Liner...One-dimensional 2-D Two-dimensional ALE3D Arbitrary-Lagrange-Eulerian (3-D) Computer Code ALEGRA 3-D Arbitrary-Lagrange-Eulerian Computer Code for...case-liner bond areas and in the grain inner bore to explore the pre-ignition and ignition phases , as well as burning evolution in rocket motor fast

Magnetoresistance measurement of permalloy thin film rings with triangular fins

NASA Astrophysics Data System (ADS)

Lai, Mei-Feng; Hsu, Chia-Jung; Liao, Chun-Neng; Chen, Ying-Jiun; Wei, Zung-Hang

2010-01-01

Magnetization reversals in permalloy rings controlled by nucleation sites using triangular fins at the same side and diagonal with respect to the field direction are demonstrated by magnetoresistance measurement and micromagnetic simulation. In the ring with triangular fins at the same side, there exists two-step reversal from onion to flux-closure state (or vortex state) and then from flux-closure (or vortex state) to reverse onion state; in the ring with diagonal triangular fins, one-step reversal occurs directly from onion to reverse onion state. The reversal processes are repeatable and controllable in contrast to an ideal ring without triangular fins where one-step and two-step reversals occur randomly in sweep-up and sweep-down processes.

Benchmarks of simple, generic, shaped plates for validation of low-frequency electromagnetic computational codes

NASA Technical Reports Server (NTRS)

Deshpande, M. D.; Cockrell, C. R.; Beck, F. B.; Nguyen, T. X.

1993-01-01

The validation of low-frequency measurements and electromagnetic (EM) scattering computations for several simple, generic shapes, such as an equilateral-triangular plate, an equilateral-triangular plate with a concentric equilateral-triangular hole, and diamond- and hexagonal-shaped plates, is discussed. The plates were constructed from a thin aluminum sheet with a thickness of 0.08 cm. EM scattering by the planar plates was measured in the experimental test range (ETR) facility of NASA Langley Research Center. The dimensions of the plates were selected such that, over the frequency range of interest, the dimensions were in the range of lambda0 to 3(lambda0). In addition, the triangular plate with a triangular hole was selected to study internal-hole resonances.

Creating unconventional geometric beams with large depth of field using double freeform-surface optics.

PubMed

Feng, Zexin; Froese, Brittany D; Huang, Chih-Yu; Ma, Donglin; Liang, Rongguang

2015-07-10

We consider here creation of an unconventional flattop beam with a large depth of field by employing double freeform optical surfaces. The output beam is designed with continuous variations from the flattop to almost zero near the edges to resist the influence of diffraction on its propagation. We solve this challenging problem by naturally incorporating an optimal transport map computation scheme for unconventional boundary conditions with a simultaneous point-by-point double surface construction procedure. We demonstrate experimentally the generation of a long-range propagated triangular beam through a plano-freeform lens pair fabricated by a diamond-tuning machine.

Lagrange Point Missions: the Key to Next-Generation Integrated Earth Observations. DSCOVR Innovation

NASA Astrophysics Data System (ADS)

Valero, F. P. J.

2016-12-01

From L-1 DSCOVR is capable of new, unique observations potentially conducive to a deeper scientific understanding of the Earth sciences. At L-1 and L-2 the net gravitational pull of the Earth and Sun equals the centripetal force required to orbit the Sun with the same period as the Earth. Satellites at or near L-1 and L-2 keep the same position relative to the Sun and the Earth. DSCOVR does not orbit the Earth but the Sun in synchronism with Earth, acts like a planetoid (orbits the Sun in the ecliptic plane) while acquiring integrated plus spatially and time resolved scientific data as Earth rotates around its axis. Because of the planet's axial tilt relative to the ecliptic plane, the Polar Regions are visible during local summer from L-1 and local winter from L-2 (Fig. 1). DSCOVR's synoptic and continuous observations solve most of the temporal and spatial limitations associated with low Earth (LEO) and Geostationary (GEO) orbits. Two observatories, one at L-1 (daytime) and one at L-2 (nighttime), would acquire minute-by-minute climate quality data for essentially every point on Earth. The integration of L-1, L-2, LEO, and GEO satellites plus the Moon offers new scientific tools and enriched data sets for Earth sciences. Lagrange points observatories are key to next-generation integrated Earth observations. For example, DSCOVR at L-1 views the Earth plus the Moon (a reference) and simultaneously, at one time or another, all LEO and GEO satellites. The L-1 and L-2 satellites would be the link between the Moon, LEO and GEO satellites while providing the data needed to build an integrated Earth observational system. The above properties are the bases for DSCOVR's innovation and scientific approach that systematically observes climate drivers (radiation, aerosols, ozone, clouds, water vapor, vegetation) from L-1 in a way not possible but synergistic with other satellites. Next step: more capable L-1 plus L-2 satellites. The way of the future.

7 CFR 810.1002 - Definition of other terms.

Code of Federal Regulations, 2014 CFR

2014-01-01

... seeds. All matter that passes through a 5/64 triangular-hole sieve after sieving according to procedures..., rye, safflower, sorghum, soybeans, spelt, sunflower seed, sweet corn, triticale, and wheat. (e) Sieves—(1) 5/64 triangular-hole sieve. A metal sieve 0.032 inch thick with equilateral triangular...

7 CFR 810.1002 - Definition of other terms.

Code of Federal Regulations, 2012 CFR

2012-01-01

... seeds. All matter that passes through a 5/64 triangular-hole sieve after sieving according to procedures..., rye, safflower, sorghum, soybeans, spelt, sunflower seed, sweet corn, triticale, and wheat. (e) Sieves—(1) 5/64 triangular-hole sieve. A metal sieve 0.032 inch thick with equilateral triangular...

7 CFR 810.1002 - Definition of other terms.

Code of Federal Regulations, 2013 CFR

2013-01-01

... seeds. All matter that passes through a 5/64 triangular-hole sieve after sieving according to procedures..., rye, safflower, sorghum, soybeans, spelt, sunflower seed, sweet corn, triticale, and wheat. (e) Sieves—(1) 5/64 triangular-hole sieve. A metal sieve 0.032 inch thick with equilateral triangular...

An Exposition on the Nonlinear Kinematics of Shells, Including Transverse Shearing Deformations

NASA Technical Reports Server (NTRS)

Nemeth, Michael P.

2013-01-01

An in-depth exposition on the nonlinear deformations of shells with "small" initial geometric imperfections, is presented without the use of tensors. First, the mathematical descriptions of an undeformed-shell reference surface, and its deformed image, are given in general nonorthogonal coordinates. The two-dimensional Green-Lagrange strains of the reference surface derived and simplified for the case of "small" strains. Linearized reference-surface strains, rotations, curvatures, and torsions are then derived and used to obtain the "small" Green-Lagrange strains in terms of linear deformation measures. Next, the geometry of the deformed shell is described mathematically and the "small" three-dimensional Green-Lagrange strains are given. The deformations of the shell and its reference surface are related by introducing a kinematic hypothesis that includes transverse shearing deformations and contains the classical Love-Kirchhoff kinematic hypothesis as a proper, explicit subset. Lastly, summaries of the essential equations are given for general nonorthogonal and orthogonal coordinates, and the basis for further simplification of the equations is discussed.

Augmented Lagrange Hopfield network for solving economic dispatch problem in competitive environment

NASA Astrophysics Data System (ADS)

Vo, Dieu Ngoc; Ongsakul, Weerakorn; Nguyen, Khai Phuc

2012-11-01

This paper proposes an augmented Lagrange Hopfield network (ALHN) for solving economic dispatch (ED) problem in the competitive environment. The proposed ALHN is a continuous Hopfield network with its energy function based on augmented Lagrange function for efficiently dealing with constrained optimization problems. The ALHN method can overcome the drawbacks of the conventional Hopfield network such as local optimum, long computational time, and linear constraints. The proposed method is used for solving the ED problem with two revenue models of revenue based on payment for power delivered and payment for reserve allocated. The proposed ALHN has been tested on two systems of 3 units and 10 units for the two considered revenue models. The obtained results from the proposed methods are compared to those from differential evolution (DE) and particle swarm optimization (PSO) methods. The result comparison has indicated that the proposed method is very efficient for solving the problem. Therefore, the proposed ALHN could be a favorable tool for ED problem in the competitive environment.

Holonomicity analysis of electromechanical systems

NASA Astrophysics Data System (ADS)

Wcislik, Miroslaw; Suchenia, Karol

2017-12-01

Electromechanical systems are described using state variables that contain electrical and mechanical components. The equations of motion, both electrical and mechanical, describe the relationships between these components. These equations are obtained using Lagrange functions. On the basis of the function and Lagrange - d'Alembert equation the methodology of obtaining equations for electromechanical systems was presented, together with a discussion of the nonholonomicity of these systems. The electromechanical system in the form of a single-phase reluctance motor was used to verify the presented method. Mechanical system was built as a system, which can oscillate as the element of physical pendulum. On the base of the pendulum oscillation, parameters of the electromechanical system were defined. The identification of the motor electric parameters as a function of the rotation angle was carried out. In this paper the characteristics and motion equations parameters of the motor are presented. The parameters of the motion equations obtained from the experiment and from the second order Lagrange equations are compared.

Size effects in non-linear heat conduction with flux-limited behaviors

NASA Astrophysics Data System (ADS)

Li, Shu-Nan; Cao, Bing-Yang

2017-11-01

Size effects are discussed for several non-linear heat conduction models with flux-limited behaviors, including the phonon hydrodynamic, Lagrange multiplier, hierarchy moment, nonlinear phonon hydrodynamic, tempered diffusion, thermon gas and generalized nonlinear models. For the phonon hydrodynamic, Lagrange multiplier and tempered diffusion models, heat flux will not exist in problems with sufficiently small scale. The existence of heat flux needs the sizes of heat conduction larger than their corresponding critical sizes, which are determined by the physical properties and boundary temperatures. The critical sizes can be regarded as the theoretical limits of the applicable ranges for these non-linear heat conduction models with flux-limited behaviors. For sufficiently small scale heat conduction, the phonon hydrodynamic and Lagrange multiplier models can also predict the theoretical possibility of violating the second law and multiplicity. Comparisons are also made between these non-Fourier models and non-linear Fourier heat conduction in the type of fast diffusion, which can also predict flux-limited behaviors.

A macroscopic plasma Lagrangian and its application to wave interactions and resonances

NASA Technical Reports Server (NTRS)

Peng, Y. K. M.

1974-01-01

The derivation of a macroscopic plasma Lagrangian is considered, along with its application to the description of nonlinear three-wave interaction in a homogeneous plasma and linear resonance oscillations in a inhomogeneous plasma. One approach to obtain the Lagrangian is via the inverse problem of the calculus of variations for arbitrary first and second order quasilinear partial differential systems. Necessary and sufficient conditions for the given equations to be Euler-Lagrange equations of a Lagrangian are obtained. These conditions are then used to determine the transformations that convert some classes of non-Euler-Lagrange equations to Euler-Lagrange equation form. The Lagrangians for a linear resistive transmission line and a linear warm collisional plasma are derived as examples. Using energy considerations, the correct macroscopic plasma Lagrangian is shown to differ from the velocity-integrated low Lagrangian by a macroscopic potential energy that equals twice the particle thermal kinetic energy plus the energy lost by heat conduction.

Keeping a Spacecraft on the Sun-Earth Line

NASA Technical Reports Server (NTRS)

Roithmayr, Carlos M.; Kay-Bunnell, Linda

2005-01-01

Measurements of Earth's atmosphere as it occults sunlight can be obtained advantageously from a spacecraft placed in the proximity of the Sun-Earth Lagrange point L2. Maintaining the condition of continuous solar occultation by all parts of the atmospheric disk requires that the displacement of the spacecraft perpendicular to the Sun-Earth line remains less than 200 km. However, the gravitational force exerted by the Earth s moon must be negated by propulsion in order to meet this rather tight constraint. We provide an estimate of propulsive force needed to keep the spacecraft coincident with L2, as well as estimates of velocity increments needed to maintain various trajectories in the close vicinity of L2.

Low Energy Transfer to the Moon

NASA Astrophysics Data System (ADS)

Koon, W. S.; Lo, M. W.; Marsden, J. E.; Ross, S. D.

In 1991, the Japanese Hiten mission used a low energy transfer with a ballistic capture at the Moon which required less Δ V than a standard Hohmann transfer. In this paper, we apply the dynamical systems techniques developed in our earlier work to reproduce systematically a Hiten-like mission. We approximate the Sun-Earth-Moon-spacecraft 4-body system as two 3-body systems. Using the invariant manifold structures of the Lagrange points of the 3-body systems, we are able to construct low energy transfer trajectories from the Earth which execute ballistic capture at the Moon. The techniques used in the design and construction of this trajectory may be applied in many situations.

An Overview of the Formation and Attitude Control System for the Terrestrial Planet Finder Formation Flying Interferometer

NASA Technical Reports Server (NTRS)

Scharf, Daniel P.; Hadaegh, Fred Y.; Rahman, Zahidul H.; Shields, Joel F.; Singh, Gurkipal; Wette, Matthew R.

2004-01-01

The Terrestrial Planet Finder formation flying Interferometer (TPF-I) will be a five-spacecraft, precision formation operating near the second Sun-Earth Lagrange point. As part of technology development for TPF-I, a formation and attitude control system (FACS) is being developed that achieves the precision and functionality needed for the TPF-I formation and that will be demonstrated in a distributed, real-time simulation environment. In this paper we present an overview of FACS and discuss in detail its formation estimation, guidance and control architectures and algorithms. Since FACS is currently being integrated into a high-fidelity simulation environment, component simulations demonstrating algorithm performance are presented.

An Overview of the Formation and Attitude Control System for the Terrestrial Planet Finder Formation Flying Interferometer

NASA Technical Reports Server (NTRS)

Scharf, Daniel P.; Hadaegh, Fred Y.; Rahman, Zahidul H.; Shields, Joel F.; Singh, Gurkipal

2004-01-01

The Terrestrial Planet Finder formation flying Interferometer (TPF-I) will be a five-spacecraft, precision formation operating near a Sun-Earth Lagrange point. As part of technology development for TPF-I, a formation and attitude control system (FACS) is being developed that achieves the precision and functionality associated with the TPF-I formation. This FACS will be demonstrated in a distributed, real-time simulation environment. In this paper we present an overview of the FACS and discuss in detail its constituent formation estimation, guidance and control architectures and algorithms. Since the FACS is currently being integrated into a high-fidelity simulation environment, component simulations demonstrating algorithm performance are presented.

Development of an unstructured solution adaptive method for the quasi-three-dimensional Euler and Navier-Stokes equations

NASA Technical Reports Server (NTRS)

Jiang, Yi-Tsann

1993-01-01

A general solution adaptive scheme-based on a remeshing technique is developed for solving the two-dimensional and quasi-three-dimensional Euler and Favre-averaged Navier-Stokes equations. The numerical scheme is formulated on an unstructured triangular mesh utilizing an edge-based pointer system which defines the edge connectivity of the mesh structure. Jameson's four-stage hybrid Runge-Kutta scheme is used to march the solution in time. The convergence rate is enhanced through the use of local time stepping and implicit residual averaging. As the solution evolves, the mesh is regenerated adaptively using flow field information. Mesh adaptation parameters are evaluated such that an estimated local numerical error is equally distributed over the whole domain. For inviscid flows, the present approach generates a complete unstructured triangular mesh using the advancing front method. For turbulent flows, the approach combines a local highly stretched structured triangular mesh in the boundary layer region with an unstructured mesh in the remaining regions to efficiently resolve the important flow features. One-equation and two-equation turbulence models are incorporated into the present unstructured approach. Results are presented for a wide range of flow problems including two-dimensional multi-element airfoils, two-dimensional cascades, and quasi-three-dimensional cascades. This approach is shown to gain flow resolution in the refined regions while achieving a great reduction in the computational effort and storage requirements since solution points are not wasted in regions where they are not required.

ASICs Approach for the Implementation of a Symmetric Triangular Fuzzy Coprocessor and Its Application to Adaptive Filtering

NASA Technical Reports Server (NTRS)

Starks, Scott; Abdel-Hafeez, Saleh; Usevitch, Bryan

1997-01-01

This paper discusses the implementation of a fuzzy logic system using an ASICs design approach. The approach is based upon combining the inherent advantages of symmetric triangular membership functions and fuzzy singleton sets to obtain a novel structure for fuzzy logic system application development. The resulting structure utilizes a fuzzy static RAM to store the rule-base and the end-points of the triangular membership functions. This provides advantages over other approaches in which all sampled values of membership functions for all universes must be stored. The fuzzy coprocessor structure implements the fuzzification and defuzzification processes through a two-stage parallel pipeline architecture which is capable of executing complex fuzzy computations in less than 0.55us with an accuracy of more than 95%, thus making it suitable for a wide range of applications. Using the approach presented in this paper, a fuzzy logic rule-base can be directly downloaded via a host processor to an onchip rule-base memory with a size of 64 words. The fuzzy coprocessor's design supports up to 49 rules for seven fuzzy membership functions associated with each of the chip's two input variables. This feature allows designers to create fuzzy logic systems without the need for additional on-board memory. Finally, the paper reports on simulation studies that were conducted for several adaptive filter applications using the least mean squared adaptive algorithm for adjusting the knowledge rule-base.

Designing Tripodal and Triangular Gadolinium Oxide Nanoplates and Self-Assembled Nanofibrils as Potential Multimodal Bioimaging Probes

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

Paik, T; Gordon, TR; Prantner, AM

2013-03-01

Here, we report the shape-controlled synthesis of tripodal and triangular gadolinium oxide (Gd2O3) nanoplates. In the presence of lithium ions, the shape of the nanocrystals is readily controlled by tailoring reaction parameters such as temperature and time. We observe that the morphology transforms from an initial tripodal shape to a triangular shape with increasing reaction time or elevated temperatures. Highly uniform Gd2O3 nanoplates are self-assembled into nanofibril-like liquid-crystalline superlattices with long-range orientational and positional order. In addition, shape-directed self-assemblies are investigated by tailoring the aspect ratio of the arms of the Gd2O3 nanoplates. Due to a strong paramagnetic response, Gd2O3more » nanocrystals are excellent candidates for MRI contrast agents and also can be doped with rare-earth ions to form nanophosphors, pointing to their potential in multimodal imaging. In this work, we investigate the MR relaxometry at high magnetic fields (9,4 and 14.1 T) and the optical properties including near-IR to visible upconversion luminescence and X-ray excited optical luminescence of doped Gd2O3 nanoplates. The complex shape of Gd2O3 nanoplates, coupled with their magnetic properties and their ability to phosphoresce under NIR or X-ray excitation which penetrate deep into tissue, makes these nanoplates a promising platform for multimodal imaging in biomedical applications.« less

Development of an unstructured solution adaptive method for the quasi-three-dimensional Euler and Navier-Stokes equations

NASA Technical Reports Server (NTRS)

Jiang, Yi-Tsann; Usab, William J., Jr.

1993-01-01

A general solution adaptive scheme based on a remeshing technique is developed for solving the two-dimensional and quasi-three-dimensional Euler and Favre-averaged Navier-Stokes equations. The numerical scheme is formulated on an unstructured triangular mesh utilizing an edge-based pointer system which defines the edge connectivity of the mesh structure. Jameson's four-stage hybrid Runge-Kutta scheme is used to march the solution in time. The convergence rate is enhanced through the use of local time stepping and implicit residual averaging. As the solution evolves, the mesh is regenerated adaptively using flow field information. Mesh adaptation parameters are evaluated such that an estimated local numerical error is equally distributed over the whole domain. For inviscid flows, the present approach generates a complete unstructured triangular mesh using the advancing front method. For turbulent flows, the approach combines a local highly stretched structured triangular mesh in the boundary layer region with an unstructured mesh in the remaining regions to efficiently resolve the important flow features. One-equation and two-equation turbulence models are incorporated into the present unstructured approach. Results are presented for a wide range of flow problems including two-dimensional multi-element airfoils, two-dimensional cascades, and quasi-three-dimensional cascades. This approach is shown to gain flow resolution in the refined regions while achieving a great reduction in the computational effort and storage requirements since solution points are not wasted in regions where they are not required.

Triangular Diagrams Teach Steady and Dynamic Behaviour of Catalytic Reactions.

ERIC Educational Resources Information Center

Klusacek, K.; And Others

1989-01-01

Illustrates how triangular diagrams can aid in presenting some of the rather complex transient interactions that occur among gas and surface species during heterogeneous catalytic reactions. The basic equations and numerical examples are described. Classroom use of the triangular diagram is discussed. Several diagrams and graphs are provided. (YP)

On Certain Topological Indices of Boron Triangular Nanotubes

NASA Astrophysics Data System (ADS)

Aslam, Adnan; Ahmad, Safyan; Gao, Wei

2017-08-01

The topological index gives information about the whole structure of a chemical graph, especially degree-based topological indices that are very useful. Boron triangular nanotubes are now replacing usual carbon nanotubes due to their excellent properties. We have computed general Randić (Rα), first Zagreb (M1) and second Zagreb (M2), atom-bond connectivity (ABC), and geometric-arithmetic (GA) indices of boron triangular nanotubes. Also, we have computed the fourth version of atom-bond connectivity (ABC4) and the fifth version of geometric-arithmetic (GA5) indices of boron triangular nanotubes.

Adaptive non-predictor control of lower triangular uncertain nonlinear systems with an unknown time-varying delay in the input

NASA Astrophysics Data System (ADS)

Koo, Min-Sung; Choi, Ho-Lim

2018-01-01

In this paper, we consider a control problem for a class of uncertain nonlinear systems in which there exists an unknown time-varying delay in the input and lower triangular nonlinearities. Usually, in the existing results, input delays have been coupled with feedforward (or upper triangular) nonlinearities; in other words, the combination of lower triangular nonlinearities and input delay has been rare. Motivated by the existing controller for input-delayed chain of integrators with nonlinearity, we show that the control of input-delayed nonlinear systems with two particular types of lower triangular nonlinearities can be done. As a control solution, we propose a newly designed feedback controller whose main features are its dynamic gain and non-predictor approach. Three examples are given for illustration.

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

Kuprat, A.P.; Glasser, A.H.

The authors discuss unstructured grids for application to transport in the tokamak edge SOL. They have developed a new metric with which to judge element elongation and resolution requirements. Using this method, the authors apply a standard moving finite element technique to advance the SOL equations while inserting/deleting dynamically nodes that violate an elongation criterion. In a tokamak plasma, this method achieves a more uniform accuracy, and results in highly stretched triangular finite elements, except near separatrix X-point where transport is more isotropic.

Computational Fluid Dynamics (CFD) Simulations of a Finned Projectile with Microflaps for Flow Control

DTIC Science & Technology

2016-04-01

fields associated with these control mechanisms for US Army weapons are complex, involving 3-dimensional (3-D) shock- boundary layer interactions...distribution over the rear finned section and thus produce control forces and moments. Dykes et al.6 used a flat - plate fin interaction design of...cells—tetrahedrals, triangular prisms, and pyramids—were used in the mesh. Grid points shown in Fig. 3a were clustered in the boundary layer region

Anomalous finite-size effect due to quasidegenerate phases in triangular antiferromagnets with long-range interactions and mapping to the generalized six-state clock model

NASA Astrophysics Data System (ADS)

Nishino, Masamichi; Miyashita, Seiji

2016-11-01

The effect of long-range (LR) interactions on frustrated-spin models is an interesting problem, which provides rich ordering processes. We study the effect of LR interactions on triangular Ising antiferromagnets with the next-nearest-neighbor ferromagnetic interaction (TIAFF). In the thermodynamic limit, the LRTIAFF model should reproduce the corresponding mean-field results, in which successive phase transitions occur among various phases, i.e., the disordered paramagnetic phase, so-called partially disordered phase, three-sublattice ferrimagnetic phase, and two-sublattice ferrimagnetic phase. In the present paper we focus on the magnetic susceptibility at the transition point between the two-sublattice ferrimagnetic and the disordered paramagnetic phases at relatively large ferromagnetic interactions. In the mean-field analysis, the magnetic susceptibility shows no divergence at the transition point. In contrast, a divergencelike enhancement of the susceptibility is observed in Monte Carlo simulations in finite-size systems. We investigate the origin of this difference and find that it is attributed to a virtual degeneracy of the free energies of the partially disordered and 2-FR phases. We also exploit a generalized six-state clock model with an LR interaction, which is a more general system with Z6 symmetry. We discuss the phase diagram of this model and find that it exhibits richer transition patterns and contains the physics of the LRTIAFF model.

Heat transfer and pressure drop characteristics of the tube bank fin heat exchanger with fin punched with flow redistributors and curved triangular vortex generators

NASA Astrophysics Data System (ADS)

Liu, Song; Jin, Hua; Song, KeWei; Wang, LiangChen; Wu, Xiang; Wang, LiangBi

2017-10-01

The heat transfer performance of the tube bank fin heat exchanger is limited by the air-side thermal resistance. Thus, enhancing the air-side heat transfer is an effective method to improve the performance of the heat exchanger. A new fin pattern with flow redistributors and curved triangular vortex generators is experimentally studied in this paper. The effects of the flow redistributors located in front of the tube stagnation point and the curved vortex generators located around the tube on the characteristics of heat transfer and pressure drop are discussed in detail. A performance comparison is also carried out between the fins with and without flow redistributors. The experimental results show that the flow redistributors stamped out from the fin in front of the tube stagnation points can decrease the friction factor at the cost of decreasing the heat transfer performance. Whether the combination of the flow redistributors and the curved vortex generators will present a better heat transfer performance depends on the size of the curved vortex generators. As for the studied two sizes of vortex generators, the heat transfer performance is promoted by the flow redistributors for the fin with larger size of vortex generators and the performance is suppressed by the flow redistributors for the fin with smaller vortex generators.

Higher-order triangular spectral element method with optimized cubature points for seismic wavefield modeling

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

Liu, Youshan, E-mail: ysliu@mail.iggcas.ac.cn; Teng, Jiwen, E-mail: jwteng@mail.iggcas.ac.cn; Xu, Tao, E-mail: xutao@mail.iggcas.ac.cn

2017-05-01

The mass-lumped method avoids the cost of inverting the mass matrix and simultaneously maintains spatial accuracy by adopting additional interior integration points, known as cubature points. To date, such points are only known analytically in tensor domains, such as quadrilateral or hexahedral elements. Thus, the diagonal-mass-matrix spectral element method (SEM) in non-tensor domains always relies on numerically computed interpolation points or quadrature points. However, only the cubature points for degrees 1 to 6 are known, which is the reason that we have developed a p-norm-based optimization algorithm to obtain higher-order cubature points. In this way, we obtain and tabulate newmore » cubature points with all positive integration weights for degrees 7 to 9. The dispersion analysis illustrates that the dispersion relation determined from the new optimized cubature points is comparable to that of the mass and stiffness matrices obtained by exact integration. Simultaneously, the Lebesgue constant for the new optimized cubature points indicates its surprisingly good interpolation properties. As a result, such points provide both good interpolation properties and integration accuracy. The Courant–Friedrichs–Lewy (CFL) numbers are tabulated for the conventional Fekete-based triangular spectral element (TSEM), the TSEM with exact integration, and the optimized cubature-based TSEM (OTSEM). A complementary study demonstrates the spectral convergence of the OTSEM. A numerical example conducted on a half-space model demonstrates that the OTSEM improves the accuracy by approximately one order of magnitude compared to the conventional Fekete-based TSEM. In particular, the accuracy of the 7th-order OTSEM is even higher than that of the 14th-order Fekete-based TSEM. Furthermore, the OTSEM produces a result that can compete in accuracy with the quadrilateral SEM (QSEM). The high accuracy of the OTSEM is also tested with a non-flat topography model. In terms of computational efficiency, the OTSEM is more efficient than the Fekete-based TSEM, although it is slightly costlier than the QSEM when a comparable numerical accuracy is required. - Highlights: • Higher-order cubature points for degrees 7 to 9 are developed. • The effects of quadrature rule on the mass and stiffness matrices has been conducted. • The cubature points have always positive integration weights. • Freeing from the inversion of a wide bandwidth mass matrix. • The accuracy of the TSEM has been improved in about one order of magnitude.« less

7 CFR 810.802 - Definition of other terms.

Code of Federal Regulations, 2012 CFR

2012-01-01

... and fines. All matter other than whole flaxseed that passes through a 5/64 triangular-hole sieve, and... established under the Act, that are materially discolored and damaged by heat. (e) Sieve— 5/64 triangular-hole sieve. A metal sieve 0.032 inch thick with equilateral triangular perforations the inscribed circles of...

7 CFR 810.802 - Definition of other terms.

Code of Federal Regulations, 2013 CFR

2013-01-01

... and fines. All matter other than whole flaxseed that passes through a 5/64 triangular-hole sieve, and... established under the Act, that are materially discolored and damaged by heat. (e) Sieve— 5/64 triangular-hole sieve. A metal sieve 0.032 inch thick with equilateral triangular perforations the inscribed circles of...

7 CFR 810.802 - Definition of other terms.

Code of Federal Regulations, 2011 CFR

2011-01-01

... and fines. All matter other than whole flaxseed that passes through a 5/64 triangular-hole sieve, and... established under the Act, that are materially discolored and damaged by heat. (e) Sieve— 5/64 triangular-hole sieve. A metal sieve 0.032 inch thick with equilateral triangular perforations the inscribed circles of...

7 CFR 810.802 - Definition of other terms.

Code of Federal Regulations, 2014 CFR

2014-01-01

... and fines. All matter other than whole flaxseed that passes through a 5/64 triangular-hole sieve, and... established under the Act, that are materially discolored and damaged by heat. (e) Sieve— 5/64 triangular-hole sieve. A metal sieve 0.032 inch thick with equilateral triangular perforations the inscribed circles of...

Sorption of Triangular Silver Nanoplates on Polyurethane Foam

NASA Astrophysics Data System (ADS)

Furletov, A. A.; Apyari, V. V.; Garshev, A. V.; Volkov, P. A.; Tolmacheva, V. V.; Dmitrienko, S. G.

2018-02-01

The sorption of triangular silver nanoplates on polyurethane foam is investigated as a procedure for creating a nanocomposite sensing material for subsequent use in optical means of chemical analysis. Triangular silver nanoplates are synthesized and characterized, and a simple sorption technique for the formation of a composite material based on these nanoplates is proposed.

Properties of plane discrete Poisson-Voronoi tessellations on triangular tiling formed by the Kolmogorov-Johnson-Mehl-Avrami growth of triangular islands

NASA Astrophysics Data System (ADS)

Korobov, A.

2011-08-01

Discrete uniform Poisson-Voronoi tessellations of two-dimensional triangular tilings resulting from the Kolmogorov-Johnson-Mehl-Avrami (KJMA) growth of triangular islands have been studied. This shape of tiles and islands, rarely considered in the field of random tessellations, is prompted by the birth-growth process of Ir(210) faceting. The growth mode determines a triangular metric different from the Euclidean metric. Kinetic characteristics of tessellations appear to be metric sensitive, in contrast to area distributions. The latter have been studied for the variant of nuclei growth to the first impingement in addition to the conventional case of complete growth. Kiang conjecture works in both cases. The averaged number of neighbors is six for all studied densities of random tessellations, but neighbors appear to be mainly different in triangular and Euclidean metrics. Also, the applicability of the obtained results for simulating birth-growth processes when the 2D nucleation and impingements are combined with the 3D growth in the particular case of similar shape and the same orientation of growing nuclei is briefly discussed.

Properties of plane discrete Poisson-Voronoi tessellations on triangular tiling formed by the Kolmogorov-Johnson-Mehl-Avrami growth of triangular islands.

PubMed

Korobov, A

2011-08-01

Discrete uniform Poisson-Voronoi tessellations of two-dimensional triangular tilings resulting from the Kolmogorov-Johnson-Mehl-Avrami (KJMA) growth of triangular islands have been studied. This shape of tiles and islands, rarely considered in the field of random tessellations, is prompted by the birth-growth process of Ir(210) faceting. The growth mode determines a triangular metric different from the Euclidean metric. Kinetic characteristics of tessellations appear to be metric sensitive, in contrast to area distributions. The latter have been studied for the variant of nuclei growth to the first impingement in addition to the conventional case of complete growth. Kiang conjecture works in both cases. The averaged number of neighbors is six for all studied densities of random tessellations, but neighbors appear to be mainly different in triangular and Euclidean metrics. Also, the applicability of the obtained results for simulating birth-growth processes when the 2D nucleation and impingements are combined with the 3D growth in the particular case of similar shape and the same orientation of growing nuclei is briefly discussed.

A Ranking Analysis/An Interlinking Approach of New Triangular Fuzzy Cognitive Maps and Combined Effective Time Dependent Matrix

NASA Astrophysics Data System (ADS)

Adiga, Shreemathi; Saraswathi, A.; Praveen Prakash, A.

2018-04-01

This paper aims an interlinking approach of new Triangular Fuzzy Cognitive Maps (TrFCM) and Combined Effective Time Dependent (CETD) matrix to find the ranking of the problems of Transgenders. Section one begins with an introduction that briefly describes the scope of Triangular Fuzzy Cognitive Maps (TrFCM) and CETD Matrix. Section two provides the process of causes of problems faced by Transgenders using Fuzzy Triangular Fuzzy Cognitive Maps (TrFCM) method and performs the calculations using the collected data among the Transgender. In Section 3, the reasons for the main causes for the problems of the Transgenders. Section 4 describes the Charles Spearmans coefficients of rank correlation method by interlinking of Triangular Fuzzy Cognitive Maps (TrFCM) Method and CETD Matrix. Section 5 shows the results based on our study.

Proceedings of the Annual Symposium on Frequency Control (33rd) Held in Atlantic City, New Jersey on 30 May-1 June 1979

DTIC Science & Technology

1979-01-01

from the Bernoullis was Daniel Bernoulli’s n’est pas la meme dans tous les sens", Exercices addition of the acceleration term to the beam e- de Math...frequencies). improved during 1811-1816 by Germain and Lagrange and, finally, the correct derivation was produced 1852 G. Lame, "Leqons sur la ...de la re- tropic membranes and plates (low frequencies) sistance des solides et des solides d’egale by Euler, Jacques Bernoulli, Germin, Lagrange

A novel iterative scheme and its application to differential equations.

PubMed

Khan, Yasir; Naeem, F; Šmarda, Zdeněk

2014-01-01

The purpose of this paper is to employ an alternative approach to reconstruct the standard variational iteration algorithm II proposed by He, including Lagrange multiplier, and to give a simpler formulation of Adomian decomposition and modified Adomian decomposition method in terms of newly proposed variational iteration method-II (VIM). Through careful investigation of the earlier variational iteration algorithm and Adomian decomposition method, we find unnecessary calculations for Lagrange multiplier and also repeated calculations involved in each iteration, respectively. Several examples are given to verify the reliability and efficiency of the method.

Euler-Lagrange formulas for pseudo-Kähler manifolds

NASA Astrophysics Data System (ADS)

Park, JeongHyeong

2016-01-01

Let c be a characteristic form of degree k which is defined on a Kähler manifold of real dimension m > 2 k. Taking the inner product with the Kähler form Ωk gives a scalar invariant which can be considered as a generalized Lovelock functional. The associated Euler-Lagrange equations are a generalized Einstein-Gauss-Bonnet gravity theory; this theory restricts to the canonical formalism if c =c2 is the second Chern form. We extend previous work studying these equations from the Kähler to the pseudo-Kähler setting.

An inverse problem strategy based on forward model evaluations: Gradient-based optimization without adjoint solves

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

Aguilo Valentin, Miguel Alejandro

2016-07-01

This study presents a new nonlinear programming formulation for the solution of inverse problems. First, a general inverse problem formulation based on the compliance error functional is presented. The proposed error functional enables the computation of the Lagrange multipliers, and thus the first order derivative information, at the expense of just one model evaluation. Therefore, the calculation of the Lagrange multipliers does not require the solution of the computationally intensive adjoint problem. This leads to significant speedups for large-scale, gradient-based inverse problems.

Evolution of triangular topographic facets along active normal faults

NASA Astrophysics Data System (ADS)

Balogun, A.; Dawers, N. H.; Gasparini, N. M.; Giachetta, E.

2011-12-01

Triangular shaped facets, which are generally formed by the erosion of fault - bounded mountain ranges, are arguably one of the most prominent geomorphic features on active normal fault scarps. Some previous studies of triangular facet development have suggested that facet size and slope exhibit a strong linear dependency on fault slip rate, thus linking their growth directly to the kinematics of fault initiation and linkage. Other studies, however, generally conclude that there is no variation in triangular facet geometry (height and slope) with fault slip rate. The landscape of the northeastern Basin and Range Province of the western United States provides an opportunity for addressing this problem. This is due to the presence of well developed triangular facets along active normal faults, as well as spatial variations in fault scale and slip rate. In addition, the Holocene climatic record for this region suggests a dominant tectonic regime, as the faulted landscape shows little evidence of precipitation gradients associated with tectonic uplift. Using GIS-based analyses of USGS 30 m digital elevation data (DEMs) for east - central Idaho and southwestern Montana, we analyze triangular facet geometries along fault systems of varying number of constituent segments. This approach allows us to link these geometries with established patterns of along - strike slip rate variation. For this study, we consider major watersheds to include only catchments with upstream and downstream boundaries extending from the drainage divide to the mapped fault trace, respectively. In order to maintain consistency in the selection criteria for the analyzed triangular facets, only facets bounded on opposite sides by major watersheds were considered. Our preliminary observations reflect a general along - strike increase in the surface area, average slope, and relief of triangular facets from the tips of the fault towards the center. We attribute anomalies in the along - strike geometric measurements of the triangular facets to represent possible locations of fault segment linkage associated with normal fault evolution.

Gene Expression Data to Mouse Atlas Registration Using a Nonlinear Elasticity Smoother and Landmark Points Constraints

PubMed Central

Lin, Tungyou; Guyader, Carole Le; Dinov, Ivo; Thompson, Paul; Toga, Arthur; Vese, Luminita

2013-01-01

This paper proposes a numerical algorithm for image registration using energy minimization and nonlinear elasticity regularization. Application to the registration of gene expression data to a neuroanatomical mouse atlas in two dimensions is shown. We apply a nonlinear elasticity regularization to allow larger and smoother deformations, and further enforce optimality constraints on the landmark points distance for better feature matching. To overcome the difficulty of minimizing the nonlinear elasticity functional due to the nonlinearity in the derivatives of the displacement vector field, we introduce a matrix variable to approximate the Jacobian matrix and solve for the simplified Euler-Lagrange equations. By comparison with image registration using linear regularization, experimental results show that the proposed nonlinear elasticity model also needs fewer numerical corrections such as regridding steps for binary image registration, it renders better ground truth, and produces larger mutual information; most importantly, the landmark points distance and L2 dissimilarity measure between the gene expression data and corresponding mouse atlas are smaller compared with the registration model with biharmonic regularization. PMID:24273381

Relative Critical Points

NASA Astrophysics Data System (ADS)

Lewis, Debra

2013-05-01

Relative equilibria of Lagrangian and Hamiltonian systems with symmetry are critical points of appropriate scalar functions parametrized by the Lie algebra (or its dual) of the symmetry group. Setting aside the structures - symplectic, Poisson, or variational - generating dynamical systems from such functions highlights the common features of their construction and analysis, and supports the construction of analogous functions in non-Hamiltonian settings. If the symmetry group is nonabelian, the functions are invariant only with respect to the isotropy subgroup of the given parameter value. Replacing the parametrized family of functions with a single function on the product manifold and extending the action using the (co)adjoint action on the algebra or its dual yields a fully invariant function. An invariant map can be used to reverse the usual perspective: rather than selecting a parametrized family of functions and finding their critical points, conditions under which functions will be critical on specific orbits, typically distinguished by isotropy class, can be derived. This strategy is illustrated using several well-known mechanical systems - the Lagrange top, the double spherical pendulum, the free rigid body, and the Riemann ellipsoids - and generalizations of these systems.

Statistical Study of Turbulence: Spectral Functions and Correlation Coefficients

NASA Technical Reports Server (NTRS)

Frenkiel, Francois N.

1958-01-01

In reading the publications on turbulence of different authors, one often runs the risk of confusing the various correlation coefficients and turbulence spectra. We have made a point of defining, by appropriate concepts, the differences which exist between these functions. Besides, we introduce in the symbols a few new characteristics of turbulence. In the first chapter, we study some relations between the correlation coefficients and the different turbulence spectra. Certain relations are given by means of demonstrations which could be called intuitive rather than mathematical. In this way we demonstrate that the correlation coefficients between the simultaneous turbulent velocities at two points are identical, whether studied in Lagrange's or in Euler's systems. We then consider new spectra of turbulence, obtained by study of the simultaneous velocities along a straight line of given direction. We determine some relations between these spectra and the correlation coefficients. Examining the relation between the spectrum of the turbulence measured at a fixed point and the longitudinal-correlation curve given by G. I. Taylor, we find that this equation is exact only when the coefficient is very small.

Task-space separation principle: a force-field approach to motion planning for redundant manipulators.

PubMed

Tommasino, Paolo; Campolo, Domenico

2017-02-03

In this work, we address human-like motor planning in redundant manipulators. Specifically, we want to capture postural synergies such as Donders' law, experimentally observed in humans during kinematically redundant tasks, and infer a minimal set of parameters to implement similar postural synergies in a kinematic model. For the model itself, although the focus of this paper is to solve redundancy by implementing postural strategies derived from experimental data, we also want to ensure that such postural control strategies do not interfere with other possible forms of motion control (in the task-space), i.e. solving the posture/movement problem. The redundancy problem is framed as a constrained optimization problem, traditionally solved via the method of Lagrange multipliers. The posture/movement problem can be tackled via the separation principle which, derived from experimental evidence, posits that the brain processes static torques (i.e. posture-dependent, such as gravitational torques) separately from dynamic torques (i.e. velocity-dependent). The separation principle has traditionally been applied at a joint torque level. Our main contribution is to apply the separation principle to Lagrange multipliers, which act as task-space force fields, leading to a task-space separation principle. In this way, we can separate postural control (implementing Donders' law) from various types of tasks-space movement planners. As an example, the proposed framework is applied to the (redundant) task of pointing with the human wrist. Nonlinear inverse optimization (NIO) is used to fit the model parameters and to capture motor strategies displayed by six human subjects during pointing tasks. The novelty of our NIO approach is that (i) the fitted motor strategy, rather than raw data, is used to filter and down-sample human behaviours; (ii) our framework is used to efficiently simulate model behaviour iteratively, until it converges towards the experimental human strategies.

Habitation Concepts and Tools for Asteroid Missions and Commercial Applications

NASA Technical Reports Server (NTRS)

Smitherman, David

2010-01-01

In 2009 studies were initiated in response to the Augustine Commission s review of the Human Spaceflight Program to examine the feasibility of additional options for space exploration beyond the lunar missions planned in the Constellation Program. One approach called a Flexible Path option included possible human missions to near-Earth asteroids. This paper presents an overview of possible asteroid missions with emphasis on the habitation options and vehicle configurations conceived for the crew excursion vehicles. One launch vehicle concept investigated for the Flexible Path option was to use a dual launch architecture that could serve a wide variety of exploration goals. The dual launch concept used two medium sized heavy lift launch vehicles for lunar missions as opposed to the single Saturn V architecture used for the Apollo Program, or the one-and-a-half vehicle Ares I / Ares V architecture proposed for the Constellation Program. This dual launch approach was studied as a Flexible Path option for lunar missions and for possible excursions to other destinations like geosynchronous earth orbiting satellites, Lagrange points, and as presented in this paper, asteroid rendezvous. New habitation and exploration systems for the crew are presented that permit crew sizes from 2 to 4, and mission durations from 100 to 360 days. Vehicle configurations are presented that include habitation systems and tools derived from International Space Station (ISS) experience and new extra-vehicular activity tools for asteroid exploration, Figure 1. Findings from these studies and as presented in this paper indicate that missions to near-Earth asteroids appear feasible in the near future using the dual launch architecture, the technologies under development from the Constellation Program, and systems derived from the current ISS Program. In addition, the capabilities derived from this approach that are particularly beneficial to the commercial sector include human access to geosynchronous orbit and the Lagrange points with new tools for satellite servicing and in-space assembly.

Triangular Arbitrage as an Interaction in Foreign Exchange Markets

NASA Astrophysics Data System (ADS)

Aiba, Yukihiro; Hatano, Naomichi

Analyzing correlation in financial time series is a topic of considerable interest [1]-[17]. In the foreign exchange market, a correlation among the exchange rates can be generated by a triangular arbitrage transaction. The purpose of this article is to review our recent study [18]-[23] on modeling the interaction generated by the triangular arbitrage.

Energy variational analysis of ions in water and channels: Field theory for primitive models of complex ionic fluids

PubMed Central

Eisenberg, Bob; Hyon, YunKyong; Liu, Chun

2010-01-01

Ionic solutions are mixtures of interacting anions and cations. They hardly resemble dilute gases of uncharged noninteracting point particles described in elementary textbooks. Biological and electrochemical solutions have many components that interact strongly as they flow in concentrated environments near electrodes, ion channels, or active sites of enzymes. Interactions in concentrated environments help determine the characteristic properties of electrodes, enzymes, and ion channels. Flows are driven by a combination of electrical and chemical potentials that depend on the charges, concentrations, and sizes of all ions, not just the same type of ion. We use a variational method EnVarA (energy variational analysis) that combines Hamilton’s least action and Rayleigh’s dissipation principles to create a variational field theory that includes flow, friction, and complex structure with physical boundary conditions. EnVarA optimizes both the action integral functional of classical mechanics and the dissipation functional. These functionals can include entropy and dissipation as well as potential energy. The stationary point of the action is determined with respect to the trajectory of particles. The stationary point of the dissipation is determined with respect to rate functions (such as velocity). Both variations are written in one Eulerian (laboratory) framework. In variational analysis, an “extra layer” of mathematics is used to derive partial differential equations. Energies and dissipations of different components are combined in EnVarA and Euler–Lagrange equations are then derived. These partial differential equations are the unique consequence of the contributions of individual components. The form and parameters of the partial differential equations are determined by algebra without additional physical content or assumptions. The partial differential equations of mixtures automatically combine physical properties of individual (unmixed) components. If a new component is added to the energy or dissipation, the Euler–Lagrange equations change form and interaction terms appear without additional adjustable parameters. EnVarA has previously been used to compute properties of liquid crystals, polymer fluids, and electrorheological fluids containing solid balls and charged oil droplets that fission and fuse. Here we apply EnVarA to the primitive model of electrolytes in which ions are spheres in a frictional dielectric. The resulting Euler–Lagrange equations include electrostatics and diffusion and friction. They are a time dependent generalization of the Poisson–Nernst–Planck equations of semiconductors, electrochemistry, and molecular biophysics. They include the finite diameter of ions. The EnVarA treatment is applied to ions next to a charged wall, where layering is observed. Applied to an ion channel, EnVarA calculates a quick transient pile-up of electric charge, transient and steady flow through the channel, stationary “binding” in the channel, and the eventual accumulation of salts in “unstirred layers” near channels. EnVarA treats electrolytes in a unified way as complex rather than simple fluids. Ad hoc descriptions of interactions and flow have been used in many areas of science to deal with the nonideal properties of electrolytes. It seems likely that the variational treatment can simplify, unify, and perhaps derive and improve those descriptions. PMID:20849161

Variation in shape of the lingula in the adult human mandible

PubMed Central

TULI, A.; CHOUDHRY, R.; CHOUDHRY, S.; RAHEJA, S.; AGARWAL, S.

2000-01-01

The lingulae of both sides of 165 dry adult human mandibles, 131 males and 34 females of Indian origin, were classified by their shape into 4 types: 1, triangular; 2, truncated; 3, nodular; and 4, assimilated. Triangular lingulae were found in 226 (68.5%) sides, truncated in 52 (15.8%), nodular in 36 (10.9%) and assimilated in 16 (4.8%) sides. Triangular lingulae were found bilaterally in 110, truncated in 23, nodular in 17 and assimilated in 7 mandibles. Of the remaining 8 mandibles with different appearances on the 2 sides, 6 had a combination of triangular and truncated and 2 had nodular and assimilated. The incidence of triangular and assimilated types in the male and female mandibles are almost equal. In the truncated type it was double in the male mandibles while the nodular type was a little less than double in the female mandibles. PMID:11005723

Facile synthesis of microporous SiO2/triangular Ag composite nanostructures for photocatalysis

NASA Astrophysics Data System (ADS)

Sirohi, Sidhharth; Singh, Anandpreet; Dagar, Chakit; Saini, Gajender; Pani, Balaram; Nain, Ratyakshi

2017-11-01

In this article, we present a novel fabrication of microporous SiO2/triangular Ag nanoparticles for dye (methylene blue) adsorption and plasmon-mediated degradation. Microporous SiO2 nanoparticles with pore size <2 nm were synthesized using cetyltrimethylammonium bromide as a structure-directing agent and functionalized with APTMS ((3-aminopropyl) trimethoxysilane) to introduce amine groups. Amine-functionalized microporous silica was used for adsorption of triangular silver (Ag) nanoparticles. The synthesized microporous SiO2 nanostructures were investigated for adsorption of different dyes including methylene blue, congo red, direct green 26 and curcumin crystalline. Amine-functionalized microporous SiO2/triangular Ag nanostructures were used for plasmon-mediated photocatalysis of methylene blue. The experimental results revealed that the large surface area of microporous silica facilitated adsorption of dye. Triangular Ag nanoparticles, due to their better charge carrier generation and enhanced surface plasmon resonance, further enhanced the photocatalysis performance.

Strong Cosserat Elasticity in a Transversely Isotropic Polymer Lattice

NASA Astrophysics Data System (ADS)

Rueger, Z.; Lakes, R. S.

2018-02-01

Large size effects are experimentally measured in lattices of triangular unit cells: about a factor of 36 in torsion rigidity and 29 in bending rigidity. This nonclassical phenomenon is consistent with Cosserat elasticity, which allows for the rotation of points and distributed moments in addition to the translation of points and force stress of classical elasticity. The Cosserat characteristic length for torsion is ℓt=9.4 mm ; for bending, it is ℓb=8.8 mm ; these values are comparable to the cell size. Nonclassical effects are much stronger than in stretch-dominated lattices with uniform straight ribs. The lattice structure provides a path to the attainment of arbitrarily large effects.

Corkscrew point spread function for far-field three-dimensional nanoscale localization of pointlike objects

PubMed Central

Lew, Matthew D.; Lee, Steven F.; Badieirostami, Majid; Moerner, W. E.

2011-01-01

We describe the corkscrew point spread function (PSF), which can localize objects in three dimensions throughout a 3.2 µm depth of field with nanometer precision. The corkscrew PSF rotates as a function of the axial (z) position of an emitter. Fisher information calculations show that the corkscrew PSF can achieve nanometer localization precision with limited numbers of photons. We demonstrate three-dimensional super-resolution microscopy with the corkscrew PSF by imaging beads on the surface of a triangular polydimethylsiloxane (PDMS) grating. With 99,000 photons detected, the corkscrew PSF achieves a localization precision of 2.7 nm in x, 2.1 nm in y, and 5.7 nm in z. PMID:21263500

Corkscrew point spread function for far-field three-dimensional nanoscale localization of pointlike objects.

PubMed

Lew, Matthew D; Lee, Steven F; Badieirostami, Majid; Moerner, W E

2011-01-15

We describe the corkscrew point spread function (PSF), which can localize objects in three dimensions throughout a 3.2 μm depth of field with nanometer precision. The corkscrew PSF rotates as a function of the axial (z) position of an emitter. Fisher information calculations show that the corkscrew PSF can achieve nanometer localization precision with limited numbers of photons. We demonstrate three-dimensional super-resolution microscopy with the corkscrew PSF by imaging beads on the surface of a triangular polydimethylsiloxane (PDMS) grating. With 99,000 photons detected, the corkscrew PSF achieves a localization precision of 2.7 nm in x, 2.1 nm in y, and 5.7 nm in z.

Landing Trail in 3-D

NASA Technical Reports Server (NTRS)

2004-01-01

A three-dimensional color model created using data from the Mars Exploration Rover's panoramic camera shows images of airbag drag marks on the martian surface. The triangular rock in the upper left corner is approximately 20 centimeters (8 inches) tall. The meatball-shaped rock in the upper right corner is approximately 10 centimeters (4 inches) tall. The dark portion of the surface, or 'trough' is approximately 1 centimeter (0.4 inches) deep at its deepest point. This model is displayed using software developed by NASA's Ames Research Center.

Indications, techniques, and outcomes of arthroscopic repair of scapholunate ligament and triangular fibrocartilage complex.

PubMed

Mathoulin, C L

2017-07-01

This review includes updated understanding of the roles of intrinsic and extrinsic carpal ligaments in scapholunate instability and details the author's experience of indications, arthroscopic repair methods, and outcomes of treating the instability. A classification on triangular fibrocartilage complex injuries is reviewed, followed by author's indications, methods, and outcomes of arthroscopic repair of triangular fibrocartilage complex injuries.

Localized states in a triangular set of linearly coupled complex Ginzburg-Landau equations.

PubMed

Sigler, Ariel; Malomed, Boris A; Skryabin, Dmitry V

2006-12-01

We introduce a pattern-formation model based on a symmetric system of three linearly coupled cubic-quintic complex Ginzburg-Landau equations, which form a triangular configuration. This is the simplest model of a multicore fiber laser. We identify stability regions for various types of localized patterns possible in this setting, which include stationary and breathing triangular vortices.

26 CFR 1.367(b)-14T - Acquisition of parent stock for property in triangular reorganizations (temporary).

Code of Federal Regulations, 2010 CFR

2010-04-01

... 26 Internal Revenue 4 2010-04-01 2010-04-01 false Acquisition of parent stock for property in triangular reorganizations (temporary). 1.367(b)-14T Section 1.367(b)-14T Internal Revenue INTERNAL REVENUE... § 1.367(b)-14T Acquisition of parent stock for property in triangular reorganizations (temporary). (a...

Comparative analysis of film cooling efficiency at coolant supply into a single array of triangular dimples

NASA Astrophysics Data System (ADS)

Khalatov, A. A.; Petliak, O. O.; Severin, S. D.; Panchenko, N. A.

2018-03-01

The purpose of this work is a comparative study of the physical structure and film cooling efficiency of the single array of inclined holes, placed in triangular dimples and in a trench. The software package ANSYS CFX 17.0 was used along with RANS SST turbulence model. Calculations were made in a wide range of the blowing ratio ranging from 0.5 to 2.0. Results of modeling have shown high efficiency of triangular film cooling configuration. At m ≥ 1.5, the triangular configuration is comparable with the trench configuration in terms of the film cooling efficiency.

Nonzero θ13 from the Triangular Ansatz and Leptogenesis

NASA Astrophysics Data System (ADS)

Benaoum, H. B.

2012-08-01

Recent experiments indicate a departure from the exact tri-bimaximal mixing by measure ring definitive nonzero value of θ13. Within the framework of type I seesaw mechanism, we reconstruct the triangular Dirac neutrino mass matrix from the μ - τ symmetric mass matrix. The deviation from μ - τ symmetry is then parametrized by adding dimensionless parameters yi in the triangular mass matrix. In this parametrization of the neutrino mass matrix, the nonzero value θ13 is controlled by Δy = y4 - y6. We also calculate the resulting leptogenesis and show that the triangular texture can generate the observed baryon asymmetry in the universe via leptogenesis scenario.

Influence of two different flap designs on the sequelae of mandibular third molar surgery.

PubMed

Erdogan, Ozgür; Tatlı, Ufuk; Ustün, Yakup; Damlar, Ibrahim

2011-09-01

The aim of this study was to compare the influence of triangular and envelope flaps on trismus, pain, and facial swelling after mandibular third molar surgery. Twenty healthy patients with bilateral, symmetrically impacted mandibular third molars were included in this double-blinded, prospective, cross-over, randomized study. The patients were operated with envelope flap on one side and triangular flap on the other side. Trismus was determined by measuring maximum interincisal opening, and facial swelling was evaluated using a tape measuring method. Pain was determined using visual analog scale (VAS) and recording the number of pain pills taken. The facial swelling measurements and VAS scores were lower in the envelope flap group compared to the triangular flap group. There was no significant difference between the two flap designs in operation time, maximum interincisal opening, and the number of analgesics taken. Envelope flap yields to less facial swelling and reduced VAS scores in comparison to triangular flap. There is no clinical difference in trismus between the two flap designs. Despite the higher VAS scores with triangular flap, no additional doses of analgesics were required in triangular flap.

Compressible cavitation with stochastic field method

NASA Astrophysics Data System (ADS)

Class, Andreas; Dumond, Julien

2012-11-01

Non-linear phenomena can often be well described using probability density functions (pdf) and pdf transport models. Traditionally the simulation of pdf transport requires Monte-Carlo codes based on Lagrange particles or prescribed pdf assumptions including binning techniques. Recently, in the field of combustion, a novel formulation called the stochastic field method solving pdf transport based on Euler fields has been proposed which eliminates the necessity to mix Euler and Lagrange techniques or prescribed pdf assumptions. In the present work, part of the PhD Design and analysis of a Passive Outflow Reducer relying on cavitation, a first application of the stochastic field method to multi-phase flow and in particular to cavitating flow is presented. The application considered is a nozzle subjected to high velocity flow so that sheet cavitation is observed near the nozzle surface in the divergent section. It is demonstrated that the stochastic field formulation captures the wide range of pdf shapes present at different locations. The method is compatible with finite-volume codes where all existing physical models available for Lagrange techniques, presumed pdf or binning methods can be easily extended to the stochastic field formulation.

Generalized Lagrange Jacobi Gauss-Lobatto (GLJGL) Collocation Method for Solving Linear and Nonlinear Fokker-Planck Equations

NASA Astrophysics Data System (ADS)

Parand, K.; Latifi, S.; Moayeri, M. M.; Delkhosh, M.

2018-05-01

In this study, we have constructed a new numerical approach for solving the time-dependent linear and nonlinear Fokker-Planck equations. In fact, we have discretized the time variable with Crank-Nicolson method and for the space variable, a numerical method based on Generalized Lagrange Jacobi Gauss-Lobatto (GLJGL) collocation method is applied. It leads to in solving the equation in a series of time steps and at each time step, the problem is reduced to a problem consisting of a system of algebraic equations that greatly simplifies the problem. One can observe that the proposed method is simple and accurate. Indeed, one of its merits is that it is derivative-free and by proposing a formula for derivative matrices, the difficulty aroused in calculation is overcome, along with that it does not need to calculate the General Lagrange basis and matrices; they have Kronecker property. Linear and nonlinear Fokker-Planck equations are given as examples and the results amply demonstrate that the presented method is very valid, effective, reliable and does not require any restrictive assumptions for nonlinear terms.

Distributed Fault-Tolerant Control of Networked Uncertain Euler-Lagrange Systems Under Actuator Faults.

PubMed

Chen, Gang; Song, Yongduan; Lewis, Frank L

2016-05-03

This paper investigates the distributed fault-tolerant control problem of networked Euler-Lagrange systems with actuator and communication link faults. An adaptive fault-tolerant cooperative control scheme is proposed to achieve the coordinated tracking control of networked uncertain Lagrange systems on a general directed communication topology, which contains a spanning tree with the root node being the active target system. The proposed algorithm is capable of compensating for the actuator bias fault, the partial loss of effectiveness actuation fault, the communication link fault, the model uncertainty, and the external disturbance simultaneously. The control scheme does not use any fault detection and isolation mechanism to detect, separate, and identify the actuator faults online, which largely reduces the online computation and expedites the responsiveness of the controller. To validate the effectiveness of the proposed method, a test-bed of multiple robot-arm cooperative control system is developed for real-time verification. Experiments on the networked robot-arms are conduced and the results confirm the benefits and the effectiveness of the proposed distributed fault-tolerant control algorithms.

Stereo matching and view interpolation based on image domain triangulation.

PubMed

Fickel, Guilherme Pinto; Jung, Claudio R; Malzbender, Tom; Samadani, Ramin; Culbertson, Bruce

2013-09-01

This paper presents a new approach for stereo matching and view interpolation problems based on triangular tessellations suitable for a linear array of rectified cameras. The domain of the reference image is initially partitioned into triangular regions using edge and scale information, aiming to place vertices along image edges and increase the number of triangles in textured regions. A region-based matching algorithm is then used to find an initial disparity for each triangle, and a refinement stage is applied to change the disparity at the vertices of the triangles, generating a piecewise linear disparity map. A simple post-processing procedure is applied to connect triangles with similar disparities generating a full 3D mesh related to each camera (view), which are used to generate new synthesized views along the linear camera array. With the proposed framework, view interpolation reduces to the trivial task of rendering polygonal meshes, which can be done very fast, particularly when GPUs are employed. Furthermore, the generated views are hole-free, unlike most point-based view interpolation schemes that require some kind of post-processing procedures to fill holes.

Addressing the Big-Earth-Data Variety Challenge with the Hierarchical Triangular Mesh

NASA Technical Reports Server (NTRS)

Rilee, Michael L.; Kuo, Kwo-Sen; Clune, Thomas; Oloso, Amidu; Brown, Paul G.; Yu, Honfeng

2016-01-01

We have implemented an updated Hierarchical Triangular Mesh (HTM) as the basis for a unified data model and an indexing scheme for geoscience data to address the variety challenge of Big Earth Data. We observe that, in the absence of variety, the volume challenge of Big Data is relatively easily addressable with parallel processing. The more important challenge in achieving optimal value with a Big Data solution for Earth Science (ES) data analysis, however, is being able to achieve good scalability with variety. With HTM unifying at least the three popular data models, i.e. Grid, Swath, and Point, used by current ES data products, data preparation time for integrative analysis of diverse datasets can be drastically reduced and better variety scaling can be achieved. In addition, since HTM is also an indexing scheme, when it is used to index all ES datasets, data placement alignment (or co-location) on the shared nothing architecture, which most Big Data systems are based on, is guaranteed and better performance is ensured. Moreover, our updated HTM encoding turns most geospatial set operations into integer interval operations, gaining further performance advantages.

Critical frontier of the triangular Ising antiferromagnet in a field

NASA Astrophysics Data System (ADS)

Qian, Xiaofeng; Wegewijs, Maarten; Blöte, Henk W.

2004-03-01

We study the critical line of the triangular Ising antiferromagnet in an external magnetic field by means of a finite-size analysis of results obtained by transfer-matrix and Monte Carlo techniques. We compare the shape of the critical line with predictions of two different theoretical scenarios. Both scenarios, while plausible, involve assumptions. The first scenario is based on the generalization of the model to a vertex model, and the assumption that the exact analytic form of the critical manifold of this vertex model is determined by the zeroes of an O(2) gauge-invariant polynomial in the vertex weights. However, it is not possible to fit the coefficients of such polynomials of orders up to 10, such as to reproduce the numerical data for the critical points. The second theoretical prediction is based on the assumption that a renormalization mapping exists of the Ising model on the Coulomb gas, and analysis of the resulting renormalization equations. It leads to a shape of the critical line that is inconsistent with the first prediction, but consistent with the numerical data.

Exact ground states for the nearest neighbor quantum XXZ model on the kagome and other lattices with triangular motifs at Jz /Jxy = - 1 / 2

NASA Astrophysics Data System (ADS)

Changlani, Hitesh; Kumar, Krishna; Kochkov, Dmitrii; Fradkin, Eduardo; Clark, Bryan

We report the existence of a quantum macroscopically degenerate ground state manifold on the nearest neighbor XXZ model on the kagome lattice at the point Jz /Jxy = - 1 / 2 . On many lattices with triangular motifs (including the kagome, sawtooth, icosidodecahedron and Shastry-Sutherland lattice for a certain choice of couplings) this Hamiltonian is found to be frustration-free with exact ground states which correspond to three-colorings of these lattices. Several results also generalize to the case of variable couplings and to other motifs (albeit with possibly more complex Hamiltonians). The degenerate manifold on the kagome lattice corresponds to a ''many-body flat band'' of interacting hard-core bosons; and for the one boson case our results also explain the well-known non-interacting flat band. On adding realistic perturbations, state selection in this manifold of quantum many-body states is discussed along with the implications for the phase diagram of the kagome lattice antiferromagnet. supported by DE-FG02-12ER46875, DMR 1408713, DE-FG02-08ER46544.

A fast direct method for block triangular Toeplitz-like with tri-diagonal block systems from time-fractional partial differential equations

NASA Astrophysics Data System (ADS)

Ke, Rihuan; Ng, Michael K.; Sun, Hai-Wei

2015-12-01

In this paper, we study the block lower triangular Toeplitz-like with tri-diagonal blocks system which arises from the time-fractional partial differential equation. Existing fast numerical solver (e.g., fast approximate inversion method) cannot handle such linear system as the main diagonal blocks are different. The main contribution of this paper is to propose a fast direct method for solving this linear system, and to illustrate that the proposed method is much faster than the classical block forward substitution method for solving this linear system. Our idea is based on the divide-and-conquer strategy and together with the fast Fourier transforms for calculating Toeplitz matrix-vector multiplication. The complexity needs O (MNlog2 ⁡ M) arithmetic operations, where M is the number of blocks (the number of time steps) in the system and N is the size (number of spatial grid points) of each block. Numerical examples from the finite difference discretization of time-fractional partial differential equations are also given to demonstrate the efficiency of the proposed method.

Distance Determination by Gated Viewing Systems Taking into Account the Illuminating Pulse Shape

NASA Astrophysics Data System (ADS)

Gorobets, V. A.; Kuntsevich, B. F.; Shabrov, D. V.

2017-11-01

For gated viewing systems with triangular and trapezoidal illuminating pulses, we have obtained the range-intensity profiles (RIPs) of the signal as the time delay was varied between the leading edges of the gate pulse and the illuminating pulse. We have established that if the duration of the illuminating pulse Δtlas is less than or equal to the duration of the gate pulse ΔtIC, then the expressions for the characteristic distances are the same as for rectangular pulses and they can be used to determine the distance to objects. When Δtlas > ΔtIC, in the case of triangular illuminating pulses the RIP is bell-shaped. For trapezoidal pulses, the RIP is bell-shaped with or without a plateau section. We propose an empirical method for determining the characteristic distances to the RIP maximum and the boundary points for the plateau section, which we then use to calculate the distance to the object. Using calibration constants, we propose a method for determining the distance to an object and we have experimentally confirmed the feasibility of this method.

Triangular Quantum Loop Topography for Machine Learning

NASA Astrophysics Data System (ADS)

Zhang, Yi; Kim, Eun-Ah

Despite rapidly growing interest in harnessing machine learning in the study of quantum many-body systems there has been little success in training neural networks to identify topological phases. The key challenge is in efficiently extracting essential information from the many-body Hamiltonian or wave function and turning the information into an image that can be fed into a neural network. When targeting topological phases, this task becomes particularly challenging as topological phases are defined in terms of non-local properties. Here we introduce triangular quantum loop (TQL) topography: a procedure of constructing a multi-dimensional image from the ''sample'' Hamiltonian or wave function using two-point functions that form triangles. Feeding the TQL topography to a fully-connected neural network with a single hidden layer, we demonstrate that the architecture can be effectively trained to distinguish Chern insulator and fractional Chern insulator from trivial insulators with high fidelity. Given the versatility of the TQL topography procedure that can handle different lattice geometries, disorder, interaction and even degeneracy our work paves the route towards powerful applications of machine learning in the study of topological quantum matters.

Fast precalculated triangular mesh algorithm for 3D binary computer-generated holograms.

PubMed

Yang, Fan; Kaczorowski, Andrzej; Wilkinson, Tim D

2014-12-10

A new method for constructing computer-generated holograms using a precalculated triangular mesh is presented. The speed of calculation can be increased dramatically by exploiting both the precalculated base triangle and GPU parallel computing. Unlike algorithms using point-based sources, this method can reconstruct a more vivid 3D object instead of a "hollow image." In addition, there is no need to do a fast Fourier transform for each 3D element every time. A ferroelectric liquid crystal spatial light modulator is used to display the binary hologram within our experiment and the hologram of a base right triangle is produced by utilizing just a one-step Fourier transform in the 2D case, which can be expanded to the 3D case by multiplying by a suitable Fresnel phase plane. All 3D holograms generated in this paper are based on Fresnel propagation; thus, the Fresnel plane is treated as a vital element in producing the hologram. A GeForce GTX 770 graphics card with 2 GB memory is used to achieve parallel computing.

Two-Year Outcomes from a Randomized Controlled Trial of Minimally Invasive Sacroiliac Joint Fusion vs. Non-Surgical Management for Sacroiliac Joint Dysfunction.

PubMed

Polly, David W; Swofford, John; Whang, Peter G; Frank, Clay J; Glaser, John A; Limoni, Robert P; Cher, Daniel J; Wine, Kathryn D; Sembrano, Jonathan N

2016-01-01

Sacroiliac joint (SIJ) dysfunction is an important and underappreciated cause of chronic low back pain. To prospectively and concurrently compare outcomes after surgical and non-surgical treatment for chronic SIJ dysfunction. One hundred and forty-eight subjects with SIJ dysfunction were randomly assigned to minimally invasive SIJ fusion with triangular titanium implants (SIJF, n = 102) or non-surgical management (NSM, n = 46). SIJ pain (measured with a 100-point visual analog scale, VAS), disability (measured with Oswestry Disability Index, ODI) and quality of life scores were collected at baseline and at scheduled visits to 24 months. Crossover from non-surgical to surgical care was allowed after the 6-month study visit was complete. Improvements in continuous measures were compared using repeated measures analysis of variance. The proportions of subjects with clinical improvement (SIJ pain improvement ≥20 points, ODI ≥15 points) and substantial clinical benefit (SIJ pain improvement ≥25 points or SIJ pain rating ≤35, ODI ≥18.8 points) were compared. In the SIJF group, mean SIJ pain improved rapidly and was sustained (mean improvement of 55.4 points) at month 24. The 6-month mean change in the NSM group (12.2 points) was substantially smaller than that in the SIJF group (by 38.3 points, p<.0001 for superiority). By month 24, 83.1% and 82.0% received either clinical improvement or substantial clinical benefit in VAS SIJ pain score. Similarly, 68.2% and 65.9% had received clinical improvement or substantial clinical benefit in ODI score at month 24. In the NSM group, these proportions were <10% with non-surgical treatment only. Parallel changes were seen for EQ-5D and SF-36, with larger changes in the surgery group at 6 months compared to NSM. The rate of adverse events related to SIJF was low and only 3 subjects assigned to SIJF underwent revision surgery within the 24-month follow-up period. In this Level 1 multicenter prospective randomized controlled trial, minimally invasive SIJF with triangular titanium implants provided larger improvements in pain, disability and quality of life compared to NSM. Improvements after SIJF persisted to 24 months. This study was approved by a local or central IRB before any subjects were enrolled. All patients provided study-specific informed consent prior to participation.

Gravity Recovery and Interior Laboratory (GRAIL) Mission: Status at the Initiation of the Science Mapping Phase

NASA Technical Reports Server (NTRS)

Zuber, Maria T.; Smith, David E.; Asmar, Sami W.; Alomon; Konopliv, Alexander S.; Lemoine, Frank G.; Melosh, H. Jay; Neumann, Gregory A.; Phillips. Roger J.; Solomon, Sean C.;

A Chang'e-4 mission concept and vision of future Chinese lunar exploration activities

NASA Astrophysics Data System (ADS)

Wang, Qiong; Liu, Jizhong

2016-10-01

A novel concept for Chinese Chang'e-4 lunar exploration mission is presented in this paper at first. After the success of Chang'e-3, its backup probe, Chang'e-4 lander/rover combination, would be upgraded and land on the unexplored lunar farside by the aid of a relay satellite near the second Earth-Moon Lagrange point. Mineralogical and geochemical surveys on the farside to study the formation and evolution of lunar crust and observations at low radio frequencies to track the signals of the Universe's Dark Ages are priorities. Follow-up Chinese lunar exploration activities before 2030 are envisioned as building a robotic lunar science station by three to five missions. Finally several methods of international cooperation are proposed.

Distributed optical fiber-based monitoring approach of spatial seepage behavior in dike engineering

NASA Astrophysics Data System (ADS)

Su, Huaizhi; Ou, Bin; Yang, Lifu; Wen, Zhiping

2018-07-01

The failure caused by seepage is the most common one in dike engineering. As to the characteristics of seepage in dike, such as longitudinal extension engineering, the randomness, strong concealment and small initial quantity order, by means of distributed fiber temperature sensor system (DTS), adopting an improved optical fiber layer layout scheme, the location of initial interpolation point of the saturation line is obtained. With the barycentric Lagrange interpolation collocation method (BLICM), the infiltrated surface of dike full-section is generated. Combined with linear optical fiber monitoring seepage method, BLICM is applied in an engineering case, which shows that a real-time seepage monitoring technique is presented in full-section of dike based on the combination method.

WMAP Observatory Thermal Design and On-Orbit Thermal Performance

NASA Technical Reports Server (NTRS)

Glazer, Stuart D.; Brown, Kimberly D.; Michalek, Theodore J.; Ancarrow, Walter C.

2003-01-01

The Wilkinson Microwave Anisotropy Probe (WMAP) observatory, launched June 30, 2001, is designed to measure the cosmic microwave background radiation with unprecedented precision and accuracy while orbiting the second Lagrange point (L2). The instrument cold stage must be cooled passively to <95K, and systematic thermal variations in selected instrument components controlled to less than 0.5 mK (rms) per spin period. This paper describes the thermal design and testing of the WMAP spacecraft and instrument. Flight thermal data for key spacecraft and instrument components are presented from launch through the first year of mission operations. Effects of solar flux variation due to the Earth's elliptical orbit about the sun, surface thermo-optical property degradations, and solar flares on instrument thermal stability are discussed.

Modelling of charged satellite motion in Earth's gravitational and magnetic fields

NASA Astrophysics Data System (ADS)

Abd El-Bar, S. E.; Abd El-Salam, F. A.

2018-05-01

In this work Lagrange's planetary equations for a charged satellite subjected to the Earth's gravitational and magnetic force fields are solved. The Earth's gravity, and magnetic and electric force components are obtained and expressed in terms of orbital elements. The variational equations of orbit with the considered model in Keplerian elements are derived. The solution of the problem in a fully analytical way is obtained. The temporal rate of changes of the orbital elements of the spacecraft are integrated via Lagrange's planetary equations and integrals of the normalized Keplerian motion obtained by Ahmed (Astron. J. 107(5):1900, 1994).

Merging of the Dirac points in electronic artificial graphene

NASA Astrophysics Data System (ADS)

Feilhauer, J.; Apel, W.; Schweitzer, L.

2015-12-01

Theory predicts that graphene under uniaxial compressive strain in an armchair direction should undergo a topological phase transition from a semimetal into an insulator. Due to the change of the hopping integrals under compression, both Dirac points shift away from the corners of the Brillouin zone towards each other. For sufficiently large strain, the Dirac points merge and an energy gap appears. However, such a topological phase transition has not yet been observed in normal graphene (due to its large stiffness) neither in any other electronic system. We show numerically and analytically that such a merging of the Dirac points can be observed in electronic artificial graphene created from a two-dimensional electron gas by application of a triangular lattice of repulsive antidots. Here, the effect of strain is modeled by tuning the distance between the repulsive potentials along the armchair direction. Our results show that the merging of the Dirac points should be observable in a recent experiment with molecular graphene.

A Real-Time Marker-Based Visual Sensor Based on a FPGA and a Soft Core Processor

PubMed Central

Tayara, Hilal; Ham, Woonchul; Chong, Kil To

2016-01-01

This paper introduces a real-time marker-based visual sensor architecture for mobile robot localization and navigation. A hardware acceleration architecture for post video processing system was implemented on a field-programmable gate array (FPGA). The pose calculation algorithm was implemented in a System on Chip (SoC) with an Altera Nios II soft-core processor. For every frame, single pass image segmentation and Feature Accelerated Segment Test (FAST) corner detection were used for extracting the predefined markers with known geometries in FPGA. Coplanar PosIT algorithm was implemented on the Nios II soft-core processor supplied with floating point hardware for accelerating floating point operations. Trigonometric functions have been approximated using Taylor series and cubic approximation using Lagrange polynomials. Inverse square root method has been implemented for approximating square root computations. Real time results have been achieved and pixel streams have been processed on the fly without any need to buffer the input frame for further implementation. PMID:27983714

MAP Attitude Control System Design and Analysis

NASA Technical Reports Server (NTRS)

Andrews, S. F.; Campbell, C. E.; Ericsson-Jackson, A. J.; Markley, F. L.; ODonnell, J. R., Jr.

1997-01-01

The Microwave Anisotropy Probe (MAP) is a follow-on to the Differential Microwave Radiometer (DMR) instrument on the Cosmic Background Explorer (COBE) spacecraft. The MAP spacecraft will perform its mission in a Lissajous orbit around the Earth-Sun L(sub 2) Lagrange point to suppress potential instrument disturbances. To make a full-sky map of cosmic microwave background fluctuations, a combination fast spin and slow precession motion will be used. MAP requires a propulsion system to reach L(sub 2), to unload system momentum, and to perform stationkeeping maneuvers once at L(sub 2). A minimum hardware, power and thermal safe control mode must also be provided. Sufficient attitude knowledge must be provided to yield instrument pointing to a standard deviation of 1.8 arc-minutes. The short development time and tight budgets require a new way of designing, simulating, and analyzing the Attitude Control System (ACS). This paper presents the design and analysis of the control system to meet these requirements.

A Novel Model to Simulate Flexural Complements in Compliant Sensor Systems

PubMed Central

Tang, Hongyan; Zhang, Dan; Guo, Sheng; Qu, Haibo

2018-01-01

The main challenge in analyzing compliant sensor systems is how to calculate the large deformation of flexural complements. Our study proposes a new model that is called the spline pseudo-rigid-body model (spline PRBM). It combines dynamic spline and the pseudo-rigid-body model (PRBM) to simulate the flexural complements. The axial deformations of flexural complements are modeled by using dynamic spline. This makes it possible to consider the nonlinear compliance of the system using four control points. Three rigid rods connected by two revolute (R) pins with two torsion springs replace the three lines connecting the four control points. The kinematic behavior of the system is described using Lagrange equations. Both the optimization and the numerical fitting methods are used for resolving the characteristic parameters of the new model. An example is given of a compliant mechanism to modify the accuracy of the model. The spline PRBM is important in expanding the applications of the PRBM to the design and simulation of flexural force sensors. PMID:29596377

A Real-Time Marker-Based Visual Sensor Based on a FPGA and a Soft Core Processor.

PubMed

Tayara, Hilal; Ham, Woonchul; Chong, Kil To

2016-12-15

This paper introduces a real-time marker-based visual sensor architecture for mobile robot localization and navigation. A hardware acceleration architecture for post video processing system was implemented on a field-programmable gate array (FPGA). The pose calculation algorithm was implemented in a System on Chip (SoC) with an Altera Nios II soft-core processor. For every frame, single pass image segmentation and Feature Accelerated Segment Test (FAST) corner detection were used for extracting the predefined markers with known geometries in FPGA. Coplanar PosIT algorithm was implemented on the Nios II soft-core processor supplied with floating point hardware for accelerating floating point operations. Trigonometric functions have been approximated using Taylor series and cubic approximation using Lagrange polynomials. Inverse square root method has been implemented for approximating square root computations. Real time results have been achieved and pixel streams have been processed on the fly without any need to buffer the input frame for further implementation.

Trajectory planning of mobile robots using indirect solution of optimal control method in generalized point-to-point task

NASA Astrophysics Data System (ADS)

Nazemizadeh, M.; Rahimi, H. N.; Amini Khoiy, K.

2012-03-01

This paper presents an optimal control strategy for optimal trajectory planning of mobile robots by considering nonlinear dynamic model and nonholonomic constraints of the system. The nonholonomic constraints of the system are introduced by a nonintegrable set of differential equations which represent kinematic restriction on the motion. The Lagrange's principle is employed to derive the nonlinear equations of the system. Then, the optimal path planning of the mobile robot is formulated as an optimal control problem. To set up the problem, the nonlinear equations of the system are assumed as constraints, and a minimum energy objective function is defined. To solve the problem, an indirect solution of the optimal control method is employed, and conditions of the optimality derived as a set of coupled nonlinear differential equations. The optimality equations are solved numerically, and various simulations are performed for a nonholonomic mobile robot to illustrate effectiveness of the proposed method.

Diagnosing central lesions of the triangular fibrocartilage as traumatic or degenerative: a review of clinical accuracy.

PubMed

Löw, S; Erne, H; Pillukat, T; Mühldorfer-Fodor, M; Unglaub, F; Spies, C K

2017-05-01

This study examined the reliability of surgeons' estimations as to whether central lesions of the triangular fibrocartilage complex were traumatic or degenerative. A total of 50 consecutive central triangular fibrocartilage complex lesions were independently rated by ten experienced wrist surgeons viewing high-quality arthroscopy videos. The videos were reassessed after intervals of 3 months; at the second assessment surgeons were given the patient's history, radiographs and both, each in a randomized order. Finally, the surgeons assessed the histories and radiographs without the videos. Kappa statistics revealed fair interrater agreement when the histories were added to the videos. The other four modalities demonstrated moderate agreement, with lower Kappa values for the assessment without videos. Intra-rater reliability showed fair agreement for three surgeons, moderate agreement for two surgeons and substantial agreement for five surgeons. It appears that classification of central triangular fibrocartilage complex lesions depends on the information provided upon viewing the triangular fibrocartilage complex at arthroscopy. II.

Patients with triangular fibrocartilage complex injuries and distal radioulnar joint instability have reduced rotational torque in the forearm.

PubMed

Andersson, J K; Axelsson, P; Strömberg, J; Karlsson, J; Fridén, J

2016-09-01

A total of 20 patients scheduled for wrist arthroscopy, all with clinical signs of rupture to the triangular fibrocartilage complex and distal radioulnar joint instability, were tested pre-operatively by an independent observer for strength of forearm rotation. During surgery, the intra-articular pathology was documented by photography and also subsequently individually analysed by another independent hand surgeon. Arthroscopy revealed a type 1-B injury to the triangular fibrocartilage complex in 18 of 20 patients. Inter-rater reliability between the operating surgeon and the independent reviewer showed absolute agreement in all but one patient (95%) in terms of the injury to the triangular fibrocartilage complex and its classification. The average pre-operative torque strength was 71% of the strength of the non-injured contralateral side in pronation and supination. Distal radioulnar joint instability with an arthroscopically verified injury to the triangular fibrocartilage complex is associated with a significant loss of both pronation and supination torque. Case series, Level IV. © The Author(s) 2015.

Anisotropic magnetic properties of the triangular plane lattice material TmMgGaO 4

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

Cevallos, F. Alex; Stolze, Karoline; Kong, Tai

Here, the crystal growth, structure, and basic magnetic properties of TmMgGaO 4 are reported. The Tm ions are located in a planar triangular lattice consisting of distorted TmO6 octahedra, while the Mg and Ga atoms randomly occupy intermediary bilayers of M-O triangular bipyramids. The Tm ions are positionally disordered. The material displays an antiferromagnetic Curie Weiss theta of ~ -20 -25 K, with no clear ordering visible in the magnetic susceptibility down to 1.8 K; the structure and magnetic properties suggest that ordering of the magnetic moments is frustrated by both structural disorder and the triangular magnetic motif. Single crystalmore » magnetization measurements indicate that the magnetic properties are highly anisotropic, with large moments measured perpendicular to the triangular planes. At 2 K, a broad step-like feature is seen in the field-dependent magnetization perpendicular to the plane on applied field near 2 Tesla.« less

[Fluorescence Resonance Energy Transfer Detection of Cobalt Ions by Silver Triangular Nanoplates and Rhodamine 6G].

PubMed

Zhang, Xiu-qing; Peng, Jun; Ling, Jian; Liu, Chao-juan; Cao, Qiu-e; Ding, Zhong-tao

2015-04-01

In the present paper, the authors studied fluorescence resonance energy transfer (FRET) phenomenon between silver triangular nanoplates and bovine serum albumin (BSA)/Rhodamine 6G fluorescence complex, and established a fluorescence method for the detection of cobalt ions. We found that when increasing the silver triangular nanoplates added to certain concentrations of fluorescent bovine serum albumin (BSA)/Rhodamine 6G complex, the fluorescence of Rhodamine 6G would be quenched up to 80% due to the FRET between the quencher and donor. However, in the presence of cobalt ions, the disassociation of the fluorescent complex from silver triangular nanoplates occurred and the fluorescence of the Rhodamine 6G recovered. The recovery of fluorescence intensity rate (I/I0) has a good relationship with the cobalt ion concentration (cCO2+) added. Thus, the authors developed a fluorescence method for the detection of cobalt ions based on the FRET of silver triangular nanoplates and Rhodamine 6G.

Simultaneous travel time tomography for updating both velocity and reflector geometry in triangular/tetrahedral cell model

NASA Astrophysics Data System (ADS)

Bai, Chao-ying; He, Lei-yu; Li, Xing-wang; Sun, Jia-yu

2018-05-01

To conduct forward and simultaneous inversion in a complex geological model, including an irregular topography (or irregular reflector or velocity anomaly), we in this paper combined our previous multiphase arrival tracking method (referred as triangular shortest-path method, TSPM) in triangular (2D) or tetrahedral (3D) cell model and a linearized inversion solver (referred to as damped minimum norms and constrained least squares problem solved using the conjugate gradient method, DMNCLS-CG) to formulate a simultaneous travel time inversion method for updating both velocity and reflector geometry by using multiphase arrival times. In the triangular/tetrahedral cells, we deduced the partial derivative of velocity variation with respective to the depth change of reflector. The numerical simulation results show that the computational accuracy can be tuned to a high precision in forward modeling and the irregular velocity anomaly and reflector geometry can be accurately captured in the simultaneous inversion, because the triangular/tetrahedral cell can be easily used to stitch the irregular topography or subsurface interface.

Simultaneous travel time tomography for updating both velocity and reflector geometry in triangular/tetrahedral cell model

NASA Astrophysics Data System (ADS)

Bai, Chao-ying; He, Lei-yu; Li, Xing-wang; Sun, Jia-yu

2017-12-01

To conduct forward and simultaneous inversion in a complex geological model, including an irregular topography (or irregular reflector or velocity anomaly), we in this paper combined our previous multiphase arrival tracking method (referred as triangular shortest-path method, TSPM) in triangular (2D) or tetrahedral (3D) cell model and a linearized inversion solver (referred to as damped minimum norms and constrained least squares problem solved using the conjugate gradient method, DMNCLS-CG) to formulate a simultaneous travel time inversion method for updating both velocity and reflector geometry by using multiphase arrival times. In the triangular/tetrahedral cells, we deduced the partial derivative of velocity variation with respective to the depth change of reflector. The numerical simulation results show that the computational accuracy can be tuned to a high precision in forward modeling and the irregular velocity anomaly and reflector geometry can be accurately captured in the simultaneous inversion, because the triangular/tetrahedral cell can be easily used to stitch the irregular topography or subsurface interface.

Solution of Volterra and Fredholm Classes of Equations via Triangular Orthogonal Function (A Combination of Right Hand Triangular Function and Left Hand Triangular Function) and Hybrid Orthogonal Function (A Combination of Sample Hold Function and Right Hand Triangular Function)

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Anirban; Ganguly, Anindita; Chatterjee, Saumya Deep

2018-04-01

In this paper the authors have dealt with seven kinds of non-linear Volterra and Fredholm classes of equations. The authors have formulated an algorithm for solving the aforementioned equation types via Hybrid Function (HF) and Triangular Function (TF) piecewise-linear orthogonal approach. In this approach the authors have reduced integral equation or integro-differential equation into equivalent system of simultaneous non-linear equation and have employed either Newton's method or Broyden's method to solve the simultaneous non-linear equations. The authors have calculated the L2-norm error and the max-norm error for both HF and TF method for each kind of equations. Through the illustrated examples, the authors have shown that the HF based algorithm produces stable result, on the contrary TF-computational method yields either stable, anomalous or unstable results.

Logical spin-filtering in a triangular network of quantum nanorings with a Rashba spin-orbit interaction

NASA Astrophysics Data System (ADS)

Dehghan, E.; Sanavi Khoshnoud, D.; Naeimi, A. S.

2018-01-01

The spin-resolved electron transport through a triangular network of quantum nanorings is studied in the presence of Rashba spin-orbit interaction (RSOI) and a magnetic flux using quantum waveguide theory. This study illustrates that, by tuning Rashba constant, magnetic flux and incoming electron energy, the triangular network of quantum rings can act as a perfect logical spin-filtering with high efficiency. By changing in the energy of incoming electron, at a proper value of the Rashba constant and magnetic flux, a reverse in the direction of spin can take place in the triangular network of quantum nanorings. Furthermore, the triangular network of quantum nanorings can be designed as a device and shows several simultaneous spintronic properties such as spin-splitter and spin-inverter. This spin-splitting is dependent on the energy of the incoming electron. Additionally, different polarizations can be achieved in the two outgoing leads from an originally incoming spin state that simulates a Stern-Gerlach apparatus.

Anisotropic magnetic properties of the triangular plane lattice material TmMgGaO 4

DOE PAGES

Cevallos, F. Alex; Stolze, Karoline; Kong, Tai; ...

2018-04-30

Here, the crystal growth, structure, and basic magnetic properties of TmMgGaO 4 are reported. The Tm ions are located in a planar triangular lattice consisting of distorted TmO6 octahedra, while the Mg and Ga atoms randomly occupy intermediary bilayers of M-O triangular bipyramids. The Tm ions are positionally disordered. The material displays an antiferromagnetic Curie Weiss theta of ~ -20 -25 K, with no clear ordering visible in the magnetic susceptibility down to 1.8 K; the structure and magnetic properties suggest that ordering of the magnetic moments is frustrated by both structural disorder and the triangular magnetic motif. Single crystalmore » magnetization measurements indicate that the magnetic properties are highly anisotropic, with large moments measured perpendicular to the triangular planes. At 2 K, a broad step-like feature is seen in the field-dependent magnetization perpendicular to the plane on applied field near 2 Tesla.« less

Zero, minimum and maximum relative radial acceleration for planar formation flight dynamics near triangular libration points in the Earth-Moon system

NASA Astrophysics Data System (ADS)

Salazar, F. J. T.; Masdemont, J. J.; Gómez, G.; Macau, E. E.; Winter, O. C.

2014-11-01

Assume a constellation of satellites is flying near a given nominal trajectory around L4 or L5 in the Earth-Moon system in such a way that there is some freedom in the selection of the geometry of the constellation. We are interested in avoiding large variations of the mutual distances between spacecraft. In this case, the existence of regions of zero and minimum relative radial acceleration with respect to the nominal trajectory will prevent from the expansion or contraction of the constellation. In the other case, the existence of regions of maximum relative radial acceleration with respect to the nominal trajectory will produce a larger expansion and contraction of the constellation. The goal of this paper is to study these regions in the scenario of the Circular Restricted Three Body Problem by means of a linearization of the equations of motion relative to the periodic orbits around L4 or L5. This study corresponds to a preliminar planar formation flight dynamics about triangular libration points in the Earth-Moon system. Additionally, the cost estimate to maintain the constellation in the regions of zero and minimum relative radial acceleration or keeping a rigid configuration is computed with the use of the residual acceleration concept. At the end, the results are compared with the dynamical behavior of the deviation of the constellation from a periodic orbit.

Triangular arbitrage as an interaction among foreign exchange rates

NASA Astrophysics Data System (ADS)

Aiba, Yukihiro; Hatano, Naomichi; Takayasu, Hideki; Marumo, Kouhei; Shimizu, Tokiko

2002-07-01

We first show that there are in fact triangular arbitrage opportunities in the spot foreign exchange markets, analyzing the time dependence of the yen-dollar rate, the dollar-euro rate and the yen-euro rate. Next, we propose a model of foreign exchange rates with an interaction. The model includes effects of triangular arbitrage transactions as an interaction among three rates. The model explains the actual data of the multiple foreign exchange rates well.

Field-design optimization with triangular heliostat pods

NASA Astrophysics Data System (ADS)

Domínguez-Bravo, Carmen-Ana; Bode, Sebastian-James; Heiming, Gregor; Richter, Pascal; Carrizosa, Emilio; Fernández-Cara, Enrique; Frank, Martin; Gauché, Paul

2016-05-01

In this paper the optimization of a heliostat field with triangular heliostat pods is addressed. The use of structures which allow the combination of several heliostats into a common pod system aims to reduce the high costs associated with the heliostat field and therefore reduces the Levelized Cost of Electricity value. A pattern-based algorithm and two pattern-free algorithms are adapted to handle the field layout problem with triangular heliostat pods. Under the Helio100 project in South Africa, a new small-scale Solar Power Tower plant has been recently constructed. The Helio100 plant has 20 triangular pods (each with 6 heliostats) whose positions follow a linear pattern. The obtained field layouts after optimization are compared against the reference field Helio100.

Zeros of Schrödinger's Radial Function Rnl(r) and Kummer's Function 1F1(-a c; z) and Their ``Angle'' Distributions

NASA Astrophysics Data System (ADS)

Tarasov, V. F.

In the present paper exact formulae for the calculation of zeros of Rnl(r) and 1F1(-a c; z), where z = 2 λ r, a = n - l - 1 >= 0 and c = 2l + 2 >= 2 are presented. For a <= 4 the method due to Tartallia and Cardono, and that due to L. Ferrai, L. Euler and J. L. Lagrange are used. In other cases (a > 4) numerical methods are employed to obtain the results (to within 10-15). For greater geometrical obviousness of the irregulary distribution (as a > 3) of zeros xk = zk - (c + a - 1) on the axis y = 0, the circular diagrams with the radius Ra = (a - 1) √ {c + a - 1} are presented for the first time. It is possible to notice some singularities of distribution of these zeros and their images - the points Tk - on the circle. For a = 3 and 4 their exact ``angle'' asymptotics (as c --> ∞) are obtained. It is shown that in the basis of the L. Ferrari, L. Euler and J.-L. Lagrange methods, using for solving the equation 1F1(-4 c; z) = 0, one Common for all these methods. equation is obtained viz., the cubic resolvent equation of FEL-type. Calculating of zeros xk of the Rnl(r) and 1F1(z) functions enable us to show the ``singular'' cases (a, c) = (4, 6), (6, 4), (8, 14), ...

Using multi-dimensional Smolyak interpolation to make a sum-of-products potential

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

Avila, Gustavo, E-mail: Gustavo-Avila@telefonica.net; Carrington, Tucker, E-mail: Tucker.Carrington@queensu.ca

2015-07-28

We propose a new method for obtaining potential energy surfaces in sum-of-products (SOP) form. If the number of terms is small enough, a SOP potential surface significantly reduces the cost of quantum dynamics calculations by obviating the need to do multidimensional integrals by quadrature. The method is based on a Smolyak interpolation technique and uses polynomial-like or spectral basis functions and 1D Lagrange-type functions. When written in terms of the basis functions from which the Lagrange-type functions are built, the Smolyak interpolant has only a modest number of terms. The ideas are tested for HONO (nitrous acid)

A Fluid Structure Algorithm with Lagrange Multipliers to Model Free Swimming

NASA Astrophysics Data System (ADS)

Sahin, Mehmet; Dilek, Ezgi

2017-11-01

A new monolithic approach is prosed to solve the fluid-structure interaction (FSI) problem with Lagrange multipliers in order to model free swimming/flying. In the present approach, the fluid domain is modeled by the incompressible Navier-Stokes equations and discretized using an Arbitrary Lagrangian-Eulerian (ALE) formulation based on the stable side-centered unstructured finite volume method. The solid domain is modeled by the constitutive laws for the nonlinear Saint Venant-Kirchhoff material and the classical Galerkin finite element method is used to discretize the governing equations in a Lagrangian frame. In order to impose the body motion/deformation, the distance between the constraint pair nodes is imposed using the Lagrange multipliers, which is independent from the frame of reference. The resulting algebraic linear equations are solved in a fully coupled manner using a dual approach (null space method). The present numerical algorithm is initially validated for the classical FSI benchmark problems and then applied to the free swimming of three linked ellipses. The authors are grateful for the use of the computing resources provided by the National Center for High Performance Computing (UYBHM) under Grant Number 10752009 and the computing facilities at TUBITAK-ULAKBIM, High Performance and Grid Computing Center.

Prediction of a Densely Loaded Particle-Laden Jet using a Euler-Lagrange Dense Spray Model

NASA Astrophysics Data System (ADS)

Pakseresht, Pedram; Apte, Sourabh V.

2017-11-01

Modeling of a dense spray regime using an Euler-Lagrange discrete-element approach is challenging because of local high volume loading. A subgrid cluster of droplets can lead to locally high void fractions for the disperse phase. Under these conditions, spatio-temporal changes in the carrier phase volume fractions, which are commonly neglected in spray simulations in an Euler-Lagrange two-way coupling model, could become important. Accounting for the carrier phase volume fraction variations, leads to zero-Mach number, variable density governing equations. Using pressure-based solvers, this gives rise to a source term in the pressure Poisson equation and a non-divergence free velocity field. To test the validity and predictive capability of such an approach, a round jet laden with solid particles is investigated using Direct Numerical Simulation and compared with available experimental data for different loadings. Various volume fractions spanning from dilute to dense regimes are investigated with and without taking into account the volume displacement effects. The predictions of the two approaches are compared and analyzed to investigate the effectiveness of the dense spray model. Financial support was provided by National Aeronautics and Space Administration (NASA).

Efficient Numerical Methods for Nonlinear-Facilitated Transport and Exchange in a Blood-Tissue Exchange Unit

PubMed Central

Poulain, Christophe A.; Finlayson, Bruce A.; Bassingthwaighte, James B.

2010-01-01

The analysis of experimental data obtained by the multiple-indicator method requires complex mathematical models for which capillary blood-tissue exchange (BTEX) units are the building blocks. This study presents a new, nonlinear, two-region, axially distributed, single capillary, BTEX model. A facilitated transporter model is used to describe mass transfer between plasma and intracellular spaces. To provide fast and accurate solutions, numerical techniques suited to nonlinear convection-dominated problems are implemented. These techniques are the random choice method, an explicit Euler-Lagrange scheme, and the MacCormack method with and without flux correction. The accuracy of the numerical techniques is demonstrated, and their efficiencies are compared. The random choice, Euler-Lagrange and plain MacCormack method are the best numerical techniques for BTEX modeling. However, the random choice and Euler-Lagrange methods are preferred over the MacCormack method because they allow for the derivation of a heuristic criterion that makes the numerical methods stable without degrading their efficiency. Numerical solutions are also used to illustrate some nonlinear behaviors of the model and to show how the new BTEX model can be used to estimate parameters from experimental data. PMID:9146808

Cusp repair in aortic valve reconstruction: does the technique affect stability?

PubMed

Aicher, Diana; Langer, Frank; Adam, Oliver; Tscholl, Dietmar; Lausberg, Henning; Schäfers, Hans-Joachim

2007-12-01

Cusp prolapse may be an isolated cause of aortic regurgitation or may exist in conjunction with dilatation of the proximal aorta. Prolapse can be corrected by central plication, triangular resection, or pericardial patch implantation. We retrospectively analyzed our results with these techniques. From October 1995 to December 2006, 604 patients (aged 3-86 years) underwent aortic valve repair. Cusp prolapse was found in 427 patients (246 tricuspid, 181 bicuspid). Prolapse was corrected by central plication (n = 275) or triangular resection (n = 80). A pericardial patch was implanted for pre-existing cusp defects or after excision of calcium (n = 72). One cusp was repaired in 198 patients; the remaining patients underwent repair of 2 (n = 189) or 3 cusps (n = 40). In 102 patients more than one technique was used, and the patients were allocated to the group of the assumedly more complex repair (central plication < triangular resection < pericardial patch plasty). Cumulative follow-up was 1238 patient-years (mean 35 +/- 27 months). Hospital mortality was 2.6% (11/427). Actuarial freedom from aortic regurgitation of grade II or more at 5 years was 92% (central plication), 90% (triangular resection), and 90% (pericardial patch plasty). Thirteen patients were reoperated on, with prolapse as the most common reason for failure (n = 7); 6 underwent re-repair. Freedom from reoperation at 5 years was 95% (central plication), 94% (triangular resection), and 94% (pericardial patch plasty). Freedom from valve replacement at 5 years was 97% (central plication), 99% (triangular resection), and 98% (pericardial patch plasty). In aortic valve repair, cusp prolapse can be treated reliably by central plication. In the presence of more complex disease, triangular resection or pericardial patch plasty may be used without compromising midterm durability.

Dependence of the L-Mode scrape-off layer power fall-off length on the upper triangularity in TCV

NASA Astrophysics Data System (ADS)

Faitsch, M.; Maurizio, R.; Gallo, A.; Coda, S.; Eich, T.; Labit, B.; Merle, A.; Reimerdes, H.; Sieglin, B.; Theiler, C.; the Eurofusion MST1 Team; the TCV Team

2018-04-01

This paper reports on experimental observations on TCV with a scan in upper triangularity {δ }up}, including negative triangularity, focusing on the power fall-off length {λ }{{q}} in L-Mode. The upper triangularity is scanned from -0.28 to 0.47. Smaller {λ }{{q}}out} is measured at the outer divertor target for decreasing {δ }up} together with higher edge temperature {T}{{e},{edge}} leading to increased confinement. This effect is observed for both magnetic drift directions for discharges in deuterium and helium. In helium larger {λ }{{q}} values are observed compared to deuterium. The power fall-off length at the inner divertor target {λ }{{q}}in} has a non-monotonic behaviour with changing triangularity. The largest values are around {δ }up}=0. The ratio {λ }{{q}}in}/{λ }{{q}}out} increases for decreasing {δ }up} for positive triangularity and is approximately constant for negative triangularity. {λ }{{q}}out} is compared to available scaling laws. Partial agreement is only observed for a scaling law containing a proxy for {T}{{e},{edge}} at ASDEX Upgrade (Sieglin 2016 Plasma Phys. Control. Fusion 58 055015). Extending this scaling to TCV and using {T}{{e},{edge}} at {ρ }pol}=0.95 suggests that {λ }{{q}}out} is independent of machine size {λ }{{q}}{{L} - {Mode}} ({mm}) = 165\\cdot {B}pol}{({{T}})}-0.66\\cdot A{({{u}})}-0.15\\cdot {T}{{e},{edge}}{({eV})}-0.93\\cdot R{({{m}})}-0.03. Possible explanations for smaller {λ }{{q}}out} for decreasing {δ }up} is a reduction in turbulence or a direct effect of increasing {T}{{e},{edge}}.

Modulation transfer function of a triangular pixel array detector.

PubMed

Karimzadeh, Ayatollah

2014-07-01

The modulation transfer function (MTF) is the main parameter that is used to evaluate image quality in electro-optical systems. Detector sampling MTF in most electro-optical systems determines the cutoff frequency of the system. The MTF of the detector depends on its pixel shape. In this work, we calculated the MTF of a detector with an equilateral triangular pixel shape. Some new results were found in deriving the MTF for the equilateral triangular pixel shape.

Galerkin finite difference Laplacian operators on isolated unstructured triangular meshes by linear combinations

NASA Technical Reports Server (NTRS)

Baumeister, Kenneth J.

1990-01-01

The Galerkin weighted residual technique using linear triangular weight functions is employed to develop finite difference formulae in Cartesian coordinates for the Laplacian operator on isolated unstructured triangular grids. The weighted residual coefficients associated with the weak formulation of the Laplacian operator along with linear combinations of the residual equations are used to develop the algorithm. The algorithm was tested for a wide variety of unstructured meshes and found to give satisfactory results.

Unitary Root Music and Unitary Music with Real-Valued Rank Revealing Triangular Factorization

DTIC Science & Technology

2010-06-01

AFRL-RY-WP-TP-2010-1213 UNITARY ROOT MUSIC AND UNITARY MUSIC WITH REAL-VALUED RANK REVEALING TRIANGULAR FACTORIZATION (Postprint) Nizar...DATES COVERED (From - To) June 2010 Journal Article Postprint 08 September 2006 – 31 August 2009 4. TITLE AND SUBTITLE UNITARY ROOT MUSIC AND...UNITARY MUSIC WITH REAL-VALUED RANK REVEALING TRIANGULAR FACTORIZATION (Postprint) 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA8650-05-D-1912-0007 5c

Are the Color Gamuts of CRT and LCD Triangular? An Experimental Study

DTIC Science & Technology

2000-07-01

UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADPO113 31 TITLE: Are the Color Gamuts of CRT and LCD Triangular? An...ADP011297 thru ADP011332 UNCLASSIFIED Are the Color Gamuts of CRT and LCD Triangular? An Experimental Study Guan-wei Leea and Chao-hua Wenb aDepartment of...Tube) display. This study describes the difference of color gamuts in different luminance level and the accuracy of color between CRT and LCD. In the

Comparison of two-transsacral-screw fixation versus triangular osteosynthesis for transforaminal sacral fractures.

PubMed

Min, Kyong S; Zamorano, David P; Wahba, George M; Garcia, Ivan; Bhatia, Nitin; Lee, Thay Q

2014-09-01

Transforaminal pelvic fractures are high-energy injuries that are translationally and rotationally unstable. This study compared the biomechanical stability of triangular osteosynthesis vs 2-transsacral-screw fixation in the repair of a transforaminal pelvic fracture model. A transforaminal fracture model was created in 10 cadaveric lumbopelvic specimens. Five of the specimens were stabilized with triangular osteosynthesis, which consisted of unilateral L5-to-ilium lumbopelvic fixation and ipsilateral iliosacral screw fixation. The remaining 5 were stabilized with a 2-transsacral-screw fixation technique that consisted of 2 transsacral screws inserted across S1. All specimens were loaded cyclically and then loaded to failure. Translation and rotation were measured using the MicroScribe 3D digitizing system (Revware Inc, Raleigh, North Carolina). The 2-transsacral-screw group showed significantly greater stiffness than the triangular osteosynthesis group (2-transsacral-screw group, 248.7 N/mm [standard deviation, 73.9]; triangular osteosynthesis group, 125.0 N/mm [standard deviation, 66.9]; P=.02); however, ultimate load and rotational stiffness were not statistically significant. Compared with triangular osteosynthesis fixation, the use of 2 transsacral screws provides a comparable biomechanical stability profile in both translation and rotation. This newly revised 2-transsacral-screw construct offers the traumatologist an alternative method of repair for vertical shear fractures that provides biplanar stability. It also offers the advantage of percutaneous placement in either the prone or supine position. Copyright 2014, SLACK Incorporated.

On the Use of the Beta Distribution in Probabilistic Resource Assessments

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

Olea, Ricardo A., E-mail: olea@usgs.gov

2011-12-15

The triangular distribution is a popular choice when it comes to modeling bounded continuous random variables. Its wide acceptance derives mostly from its simple analytic properties and the ease with which modelers can specify its three parameters through the extremes and the mode. On the negative side, hardly any real process follows a triangular distribution, which from the outset puts at a disadvantage any model employing triangular distributions. At a time when numerical techniques such as the Monte Carlo method are displacing analytic approaches in stochastic resource assessments, easy specification remains the most attractive characteristic of the triangular distribution. Themore » beta distribution is another continuous distribution defined within a finite interval offering wider flexibility in style of variation, thus allowing consideration of models in which the random variables closely follow the observed or expected styles of variation. Despite its more complex definition, generation of values following a beta distribution is as straightforward as generating values following a triangular distribution, leaving the selection of parameters as the main impediment to practically considering beta distributions. This contribution intends to promote the acceptance of the beta distribution by explaining its properties and offering several suggestions to facilitate the specification of its two shape parameters. In general, given the same distributional parameters, use of the beta distributions in stochastic modeling may yield significantly different results, yet better estimates, than the triangular distribution.« less

Triangular-shaped landforms reveal subglacial drainage routes in SW Finland

NASA Astrophysics Data System (ADS)

Mäkinen, J.; Kajuutti, K.; Palmu, J.-P.; Ojala, A.; Ahokangas, E.

2017-05-01

The aim of this study is to present the first evidence of triangular-shaped till landforms and related erosional features indicative of subglacial drainage within the ice stream bed of the Scandinavian ice sheet in Finland. Previously unidentified grouped patterns of Quaternary deposits with triangular landforms can be recognized from LiDAR-based DEMs. The triangular landforms occur as segments within geomorphologically distinguishable routes that are associated with eskers. The morphological and sedimentological characteristics as well as the distribution of the triangular landforms are interpreted to involve the creep of saturated deforming till, flow and pressure fluctuations of subglacial meltwater associated with meltwater erosion. There are no existing models for the formation of this kind of large-scale drainage systems, but we claim that they represent an efficient drainage system for subglacial meltwater transfer under high pressure conditions. Our hypothesis is that the routed, large-scale subglacial drainage systems described herein form a continuum between channelized (eskers) and more widely spread small-scale distributed subglacial drainage. Moreover, the transition from the conduit dominated drainage to triangular-shaped subglacial landforms takes place about 50-60 km from the ice margin. We provide an important contribution towards a more realistic representation of ice sheet hydrological drainage systems that could be used to improve paleoglaciological models and to simulate likely responses of ice sheets to increased meltwater production.

Simulation of Needle-Type Corona Electrodes by the Finite Element Method

NASA Astrophysics Data System (ADS)

Yang, Shiyou; José Márcio, Machado; Nancy Mieko, Abe; Angelo, Passaro

2007-12-01

This paper describes a software tool, called LEVSOFT, suitable for the electric field simulations of corona electrodes by the Finite Element Method (FEM). Special attention was paid to the user friendly construction of geometries with corners and sharp points, and to the fast generation of highly refined triangular meshes and field maps. The execution of self-adaptive meshes was also implemented. These customized features make the code attractive for the simulation of needle-type corona electrodes. Some case examples involving needle type electrodes are presented.

A new preconditioner update strategy for the solution of sequences of linear systems in structural mechanics: application to saddle point problems in elasticity

NASA Astrophysics Data System (ADS)

Mercier, Sylvain; Gratton, Serge; Tardieu, Nicolas; Vasseur, Xavier

2017-12-01

Many applications in structural mechanics require the numerical solution of sequences of linear systems typically issued from a finite element discretization of the governing equations on fine meshes. The method of Lagrange multipliers is often used to take into account mechanical constraints. The resulting matrices then exhibit a saddle point structure and the iterative solution of such preconditioned linear systems is considered as challenging. A popular strategy is then to combine preconditioning and deflation to yield an efficient method. We propose an alternative that is applicable to the general case and not only to matrices with a saddle point structure. In this approach, we consider to update an existing algebraic or application-based preconditioner, using specific available information exploiting the knowledge of an approximate invariant subspace or of matrix-vector products. The resulting preconditioner has the form of a limited memory quasi-Newton matrix and requires a small number of linearly independent vectors. Numerical experiments performed on three large-scale applications in elasticity highlight the relevance of the new approach. We show that the proposed method outperforms the deflation method when considering sequences of linear systems with varying matrices.

Extracting Information about the Rotator Cuff from Magnetic Resonance Images Using Deterministic and Random Techniques

PubMed Central

De Los Ríos, F. A.; Paluszny, M.

2015-01-01

We consider some methods to extract information about the rotator cuff based on magnetic resonance images; the study aims to define an alternative method of display that might facilitate the detection of partial tears in the supraspinatus tendon. Specifically, we are going to use families of ellipsoidal triangular patches to cover the humerus head near the affected area. These patches are going to be textured and displayed with the information of the magnetic resonance images using the trilinear interpolation technique. For the generation of points to texture each patch, we propose a new method that guarantees the uniform distribution of its points using a random statistical method. Its computational cost, defined as the average computing time to generate a fixed number of points, is significantly lower as compared with deterministic and other standard statistical techniques. PMID:25650281

A comparative study of artificial intelligent-based maximum power point tracking for photovoltaic systems

NASA Astrophysics Data System (ADS)

Hussain Mutlag, Ammar; Mohamed, Azah; Shareef, Hussain

2016-03-01

Maximum power point tracking (MPPT) is normally required to improve the performance of photovoltaic (PV) systems. This paper presents artificial intelligent-based maximum power point tracking (AI-MPPT) by considering three artificial intelligent techniques, namely, artificial neural network (ANN), adaptive neuro fuzzy inference system with seven triangular fuzzy sets (7-tri), and adaptive neuro fuzzy inference system with seven gbell fuzzy sets. The AI-MPPT is designed for the 25 SolarTIFSTF-120P6 PV panels, with the capacity of 3 kW peak. A complete PV system is modelled using 300,000 data samples and simulated in the MATLAB/SIMULINK. The AI-MPPT has been tested under real environmental conditions for two days from 8 am to 18 pm. The results showed that the ANN based MPPT gives the most accurate performance and then followed by the 7-tri-based MPPT.

The effect of wing dihedral and section suction distribution on vortex bursting

NASA Technical Reports Server (NTRS)

Washburn, K. E.; Gloss, B. B.

1975-01-01

Eleven semi-span wing models were tested in the 1/8-scale model of the Langley V/STOL tunnel to qualitatively study vortex bursting. Flow visualization was achieved by using helium filled soap bubbles introduced upstream of the model. The angle of attack range was from 0 deg to 45 deg. The results show that the vortex is unstable, that is, the bursting point location is not fixed at a given angle of attack but moves within certain bounds. Upstream of the trailing edge, the bursting point location has a range of two inches; downstream, the range is about six inches. Anhedral and dihedral appear to have an insignificant effect on the vortex and its bursting point location. Altering the section suction distribution by improving the triangularity generally increases the angle of attack at which vortex bursting occurs at the trailing edge.

Clinical results of resection arthrodesis by triangular external fixation for posttraumatic arthrosis of the ankle joint in 89 cases.

PubMed

Kiene, J; Schulz, Arndt P; Hillbricht, S; Jürgens, Ch; Paech, A

2009-01-28

The methods for ankle arthrodesis differ significantly, probably a sign that no method is clearly superior to others. In the last ten years there is a clear favour toward internal fixation. We retrospectively evaluate the technique and evaluate the clinical long term results of external fixation in a triangular frame. From 1994 to 2001 a consecutive series of 95 patients with end stage arthritis of the ankle joint were treated. Retrospectively the case notes were evaluated regarding trauma history, medical complaints, further injuries and illnesses, walking and pain status and occupational issues and the clinical examination before arthrodesis. Mean age at the index procedure was 45.4 years (18-82), 67 patients were male (70.5%). Via a bilateral approach the malleoli and the joint surfaces were resected. An AO fixator was applied with two Steinmann-nails inserted with approximately 8 cm distance in the distal tibia, one in the neck of the talus and one in the dorsal calcaneus. The fixator was removed after approximately 12 weeks. Follow up examination at mean 4.4 years included a standardised questionnaire and a clinical examination including the criteria of the AOFAS-Score and radiographs. Due to different complications, 8 (8.9%) further surgical procedures were necessary including 1 below knee amputation. In 4 patients a non-union of the ankle arthrodesis developed (4.5%). The mean AOFAS score improved from 20.8 to 69.3 points. Non-union rates and clinical results of arthrodesis by triangular external fixation of the ankle joint do not differ to internal fixation methods. The complication rate and the reduced patient comfort reserve this method mainly for infected arthritis and complicated soft tissue situations.

Clinical results of resection arthrodesis by triangular external fixation for posttraumatic arthrosis of the ankle joint in 89 cases

PubMed Central

2009-01-01

The methods for ankle arthrodesis differ significantly, probably a sign that no method is clearly superior to others. In the last ten years there is a clear favour toward internal fixation. We retrospectively evaluate the technique and evaluate the clinical long term results of external fixation in a triangular frame. Patients and Methods From 1994 to 2001 a consecutive series of 95 patients with end stage arthritis of the ankle joint were treated. Retrospectively the case notes were evaluated regarding trauma history, medical complaints, further injuries and illnesses, walking and pain status and occupational issues and the clinical examination before arthrodesis. Mean age at the index procedure was 45.4 years (18-82), 67 patients were male (70.5%). Via a bilateral approach the malleoli and the joint surfaces were resected. An AO fixator was applied with two Steinmann-nails inserted with approximately 8 cm distance in the distal tibia, one in the neck of the talus and one in the dorsal calcaneus. The fixator was removed after approximately 12 weeks. Follow up examination at mean 4.4 years included a standardised questionnaire and a clinical examination including the criteria of the AOFAS-Score and radiographs. Results: Due to different complications, 8 (8.9%) further surgical procedures were necessary including 1 below knee amputation. In 4 patients a non-union of the ankle arthrodesis developed (4.5%). The mean AOFAS score improved from 20.8 to 69.3 points. Conclusion Non-union rates and clinical results of arthrodesis by triangular external fixation of the ankle joint do not differ to internal fixation methods. The complication rate and the reduced patient comfort reserve this method mainly for infected arthritis and complicated soft tissue situations. PMID:19258207

Randomized Controlled Trial of Minimally Invasive Sacroiliac Joint Fusion Using Triangular Titanium Implants vs Nonsurgical Management for Sacroiliac Joint Dysfunction: 12-Month Outcomes.

PubMed

Polly, David W; Cher, Daniel J; Wine, Kathryn D; Whang, Peter G; Frank, Clay J; Harvey, Charles F; Lockstadt, Harry; Glaser, John A; Limoni, Robert P; Sembrano, Jonathan N

2015-11-01

Sacroiliac joint (SIJ) dysfunction is a prevalent cause of chronic, unremitting lower back pain. To concurrently compare outcomes after surgical and nonsurgical treatment for chronic SIJ dysfunction. A total of 148 subjects with SIJ dysfunction were randomly assigned to minimally invasive SIJ fusion with triangular titanium implants (n = 102) or nonsurgical management (n = 46). Pain, disability, and quality-of-life scores were collected at baseline and at 1, 3, 6, and 12 months. Success rates were compared using Bayesian methods. Crossover from nonsurgical to surgical care was allowed after the 6-month study visit was complete. Six-month success rates were higher in the surgical group (81.4% vs 26.1%; posterior probability of superiority > 0.9999). Clinically important (≥ 15 point) Oswestry Disability Index improvement at 6 months occurred in 73.3% of the SIJ fusion group vs 13.6% of the nonsurgical management group (P < .001). At 12 months, improvements in SIJ pain and Oswestry Disability Index were sustained in the surgical group. Subjects who crossed over had improvements in pain, disability, and quality of life similar to those in the original surgical group. Adverse events were slightly more common in the surgical group (1.3 vs 1.1 events per subject; P = .31). This Level 1 study showed that minimally invasive SIJ fusion using triangular titanium implants was more effective than nonsurgical management at 1 year in relieving pain, improving function, and improving quality of life in patients with SIJ dysfunction caused by degenerative sacroiliitis or SIJ disruptions. Pain, disability, and quality of life also improved after crossover from nonsurgical to surgical treatment.

Itinerant fermions on a triangular lattice: Unconventional magnetism and other ordered states

NASA Astrophysics Data System (ADS)

Ye, Mengxing; Chubukov, Andrey V.

2018-06-01

We consider a system of 2D fermions on a triangular lattice with well separated electron and hole pockets of similar sizes, centered at certain high-symmetry points in the Brillouin zone. We first analyze Stoner-type spin-density-wave (SDW) magnetism. We show that SDW order is degenerate at the mean-field level. Beyond mean-field, the degeneracy is lifted and is either 120∘ "triangular" order (same as for localized spins), or a collinear order with antiferromagnetic spin arrangement on two-thirds of sites, and nonmagnetic on the rest of sites. We also study a time-reversal symmetric directional spin bond order, which emerges when some interactions are repulsive and some are attractive. We show that this order is also degenerate at a mean-field level, but beyond mean-field the degeneracy is again lifted. We next consider the evolution of a magnetic order in a magnetic field starting from an SDW state in zero field. We show that a field gives rise to a canting of an SDW spin configuration. In addition, it necessarily triggers the directional bond order, which, we argue, is linearly coupled to the SDW order in a finite field. We derive the corresponding term in the free energy. Finally, we consider the interplay between an SDW order and superconductivity and charge order. For this, we analyze the flow of the couplings within parquet renormalization group (pRG) scheme. We show that magnetism wins if all interactions are repulsive and there is little energy space for pRG to develop. However, if system parameters are such that pRG runs over a wide range of energies, the system may develop either superconductivity or an unconventional charge order, which breaks time-reversal symmetry.

Optimal parallel solution of sparse triangular systems

NASA Technical Reports Server (NTRS)

Alvarado, Fernando L.; Schreiber, Robert

1990-01-01

A method for the parallel solution of triangular sets of equations is described that is appropriate when there are many right-handed sides. By preprocessing, the method can reduce the number of parallel steps required to solve Lx = b compared to parallel forward or backsolve. Applications are to iterative solvers with triangular preconditioners, to structural analysis, or to power systems applications, where there may be many right-handed sides (not all available a priori). The inverse of L is represented as a product of sparse triangular factors. The problem is to find a factored representation of this inverse of L with the smallest number of factors (or partitions), subject to the requirement that no new nonzero elements be created in the formation of these inverse factors. A method from an earlier reference is shown to solve this problem. This method is improved upon by constructing a permutation of the rows and columns of L that preserves triangularity and allow for the best possible such partition. A number of practical examples and algorithmic details are presented. The parallelism attainable is illustrated by means of elimination trees and clique trees.

Power transmission by laser beam from lunar-synchronous satellite

NASA Technical Reports Server (NTRS)

Williams, M. D.; Deyoung, R. J.; Schuster, G. L.; Choi, S. H.; Dagle, J. E.; Coomes, E. P.; Antoniak, Z. I.; Bamberger, J. A.; Bates, J. M.; Chiu, M. A.

1993-01-01

The possibility of beaming power from synchronous lunar orbits (the L1 and L2 Lagrange points) to a manned long-range lunar rover is addressed. The rover and two versions of a satellite system (one powered by a nuclear reactor, the other by photovoltaics) are described in terms of their masses, geometries, power needs, missions, and technological capabilities. Laser beam power is generated by a laser diode array in the satellite and converted to 30 kW of electrical power at the rover. Present technological capabilities, with some extrapolation to near future capabilities, are used in the descriptions. The advantages of the two satellite/rover systems over other such systems and over rovers with onboard power are discussed along with the possibility of enabling other missions.

Analysis of heliographic missions complementary to ISPM. [International Solar Polar Mission

NASA Technical Reports Server (NTRS)

Driver, J. M.

1984-01-01

Five concepts were formulated, analyzed, and compared for satisfying heliographic science mission objectives both with and without a concurrent International Solar Polar Mission (ISPM) Spacecraft. Key astrodynamic constraints and performance factors are known from literature for the Lagrange point mission and the sun-synchronous earth orbit mission, but are set forth in this paper for the three solar orbiting missions concepts considered. Any of these five missions should be doable at modest cost since no strong cost drivers were encountered in the analyses. The mission to be flown depends on mission capability to meet science measurement needs more than on strong economic factors. Each mission offers special advantages for particular measurement emphasis. Based on selected qualitative mission discriminators, an overall 'best mission' was selected and described in some detail.

Order Reduction, Projectability and Constraints of Second-Order Field Theories and Higher-Order Mechanics

NASA Astrophysics Data System (ADS)

Gaset, Jordi; Román-Roy, Narciso

2016-12-01

The projectability of Poincaré-Cartan forms in a third-order jet bundle J3π onto a lower-order jet bundle is a consequence of the degenerate character of the corresponding Lagrangian. This fact is analyzed using the constraint algorithm for the associated Euler-Lagrange equations in J3π. The results are applied to study the Hilbert Lagrangian for the Einstein equations (in vacuum) from a multisymplectic point of view. Thus we show how these equations are a consequence of the application of the constraint algorithm to the geometric field equations, meanwhile the other constraints are related with the fact that this second-order theory is equivalent to a first-order theory. Furthermore, the case of higher-order mechanics is also studied as a particular situation.

Analytic theory of orbit contraction and ballistic entry into planetary atmospheres

NASA Technical Reports Server (NTRS)

Longuski, J. M.; Vinh, N. X.

1980-01-01

A space object traveling through an atmosphere is governed by two forces: aerodynamic and gravitational. On this premise, equations of motion are derived to provide a set of universal entry equations applicable to all regimes of atmospheric flight from orbital motion under the dissipate force of drag through the dynamic phase of reentry, and finally to the point of contact with the planetary surface. Rigorous mathematical techniques such as averaging, Poincare's method of small parameters, and Lagrange's expansion, applied to obtain a highly accurate, purely analytic theory for orbit contraction and ballistic entry into planetary atmospheres. The theory has a wide range of applications to modern problems including orbit decay of artificial satellites, atmospheric capture of planetary probes, atmospheric grazing, and ballistic reentry of manned and unmanned space vehicles.

Observation of two new L4 Neptune Trojans in the Dark Energy Survey supernova fields

DOE PAGES

Gerdes, D. W.

2016-01-28

We report the discovery of the eighth and ninth known Trojans in stable orbits around Neptune's leading Lagrange point, L4. The objects 2014 QO 441 and 2014 QP 441 were detected in data obtained during the 2013-14 and 2014-15 observing seasons by the Dark Energy Survey, using the Dark Energy Camera (DECam) on the 4-meter Blanco telescope at Cerro Tololo Inter- American Observatory. Both are in high-inclination orbits (18.8° and 19.4° respectively). Furthermore, with an eccentricity of 0.104, 2014 QO 441 has the most eccentric orbit of the eleven known stable Neptune Trojans. We describe the search procedure and investigatemore » the objects' long-term dynamical stability and physical properties.« less

The James Webb Space Telescope

NASA Technical Reports Server (NTRS)

Mather, John C.

2004-01-01

The James Webb Space Telescope (JWST) will extend the discoveries of the Hubble Space Telescope (HST) and the Spitzer Space Telescope (SST) by deploying a large cooled infrared telescope around the Sun-Earth Lagrange point L2. With a 6 m aperture and three instruments covering the wavelength range from 0.6 to 28 microns, it will provide sensitivities orders of magnitude better than any other facilities. It is intended to observe the light from the first galaxies and the first supernovae, the assembly of galaxies, and the formation and evolution of stars and planetary systems. In this talk I will review the scientific objectives and the ability of the system to meet them. I will close with a summary of possible future IR space missions, ranging from the far IR to planet-finding coronagraphs and interferometers

Next Generation Space Telescope

NASA Technical Reports Server (NTRS)

Mather, John; Stockman, H. S.; Fisher, Richard R. (Technical Monitor)

2000-01-01

The Next Generation Space Telescope (NGST), planned for launch in 2009, will be an 8-m class radiatively cooled infrared telescope at the Lagrange point L2. It will cover the wavelength range from 0.6 to 28 microns with cameras and spectrometers, to observe the first luminous objects after the Big Bang, and the formation, growth, clustering, and evolution of galaxies, stars, and protoplanetary clouds, leading to better understanding of our own Origins. It will seek evidence of the cosmic dark matter through its gravitational effects. With an aperture three times greater than the Hubble Space Telescope, it will provide extraordinary advances in capabilities and enable the discovery of many new phenomena. It is a joint project of the NASA, ESA, and CSA, and scientific operations will be provided by the Space Telescope Science Institute.

James Webb Space Telescope Status

NASA Technical Reports Server (NTRS)

Mather, John C.

2005-01-01

The James Webb Space Telescope (JWST) is the first deployable infrared to millimeter wave space telescopes. We will describe the progress on JWST and introduce other speakers in the session. The JWST will operate at the Sun-Earth Lagrange point L2, where radiative cooling lowers the telescope and instrument temperatures to about 35 K. It will have an 18-segment beryllium primary mirror with a 25 m2 area fitting inside a 6.6m circumscribed circle, and will provide spectroscopy and imaging over the wavelength range from 0.6 to 28 microns. It is planned for launch in 2011 on an Ariane 5 rocket. The project is a partnership of NASA, ESA, and CSA, and the prime contractor is Northrop Grumman. See http://www.jwst.nasa.gov for more details on JWST.

Modelling and simulation of parallel triangular triple quantum dots (TTQD) by using SIMON 2.0

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

Fathany, Maulana Yusuf, E-mail: myfathany@gmail.com; Fuada, Syifaul, E-mail: fsyifaul@gmail.com; Lawu, Braham Lawas, E-mail: bram-labs@rocketmail.com

2016-04-19

This research presents analysis of modeling on Parallel Triple Quantum Dots (TQD) by using SIMON (SIMulation Of Nano-structures). Single Electron Transistor (SET) is used as the basic concept of modeling. We design the structure of Parallel TQD by metal material with triangular geometry model, it is called by Triangular Triple Quantum Dots (TTQD). We simulate it with several scenarios using different parameters; such as different value of capacitance, various gate voltage, and different thermal condition.

Dynamic hysteresis behaviors in the kinetic Ising system on triangular lattice

NASA Astrophysics Data System (ADS)

Kantar, Ersin; Ertaş, Mehmet

2018-04-01

We studied dynamic hysteresis behaviors of the spin-1 Blume-Capel (BC) model in a triangular lattice by means of the effective-field theory (EFT) with correlations and using Glauber-type stochastic dynamics. The effects of the exchange interaction (J), crystal field (D), temperature (T) and oscillating frequency (w) on the hysteresis behaviors of the BC model in a triangular lattice are investigated in detail. Results are compared with some other dynamic studies and quantitatively good agreement is found.

MR imaging of the traumatic triangular fibrocartilaginous complex tear

PubMed Central

Griffith, James F.; Fung, Cindy S. Y.; Lee, Ryan K. L.; Tong, Cina S. L.; Wong, Clara W. Y.; Tse, Wing Lim; Ho, Pak Cheong

2017-01-01

Triangular fibrocartilage complex is a major stabilizer of the distal radioulnar joint (DRUJ). However, triangular fibrocartilage complex (TFCC) tear is difficult to be diagnosed on MRI for its intrinsic small and thin structure with complex anatomy. The purpose of this article is to review the anatomy of TFCC, state of art MRI imaging technique, normal appearance and features of tear on MRI according to the Palmar’s classification. Atypical tear and limitations of MRI in diagnosis of TFCC tear are also discussed. PMID:28932701

Opening the Door on Triangular Numbers

ERIC Educational Resources Information Center

McMartin, Kimberley; McMaster, Heather

2016-01-01

As an alternative to looking solely at linear functions, a three-lesson learning progression developed for Year 6 students that incorporates triangular numbers to develop children's algebraic thinking is described and evaluated.

Reconstruction of the lateral tibia plateau fracture with a third triangular support screw: A biomechanical study.

PubMed

Moran, Eduardo; Zderic, Ivan; Klos, Kajetan; Simons, Paul; Triana, Miguel; Richards, R Geoff; Gueorguiev, Boyko; Lenz, Mark

2017-10-01

Split fractures of the lateral tibia plateau in young patients with good bone quality are commonly treated using two minimally invasive percutaneous lag screws, followed by unloading of the knee joint. Improved stability could be achieved with the use of a third screw inserted either in the jail-technique fashion or with a triangular support screw configuration. The aim of this study was to investigate under cyclic loading the compliance and endurance of the triangular support fixation in comparison with the standard two lag-screw fixation and the jail technique. Lateral split fractures of type AO/OTA 41-B1 were created on 21 synthetic tibiae and subsequently fixed with one of the following three techniques for seven specimens: standard fixation by inserting two partially threaded 6.5 mm cannulated lag screws parallel to each other and orthogonal to the fracture plane; triangular support fixation-standard fixation with one additional support screw at the distal end of the fracture at 30° proximal inclination; and jail fixation-standard fixation with one additional orthogonal support screw inserted in the medial nonfractured part of the bone. Mechanical testing was performed under progressively increasing cyclic compression loading. Fragment displacement was registered via triggered radiographic imaging. Mean construct compliance was 3.847 × 10 -3  mm/N [standard deviation (SD) 0.784] for standard fixation, 3.838 × 10 -3  mm/N (SD 0.242) for triangular fixation, and 3.563 × 10 -3  mm/N (SD 0.383) for jail fixation, with no significant differences between the groups ( p  = 0.525). The mean numbers of cycles to 2 mm fragment dislocation, defined as a failure criterion, were 12,384 (SD 2267) for standard fixation, 17,708 (SD 2193) for triangular fixation, and 14,629 (SD 5194) for jail fixation. Triangular fixation revealed significantly longer endurance than the standard one ( p  = 0.047). Triangular support fixation enhanced interfragmentary stability at the ultimate stage of dynamic loading. However, the level of improvement seems to be limited and may not legitimate the intervention with an additional third screw.

Comparative morphometry of facial surface models obtained from a stereo vision system in a healthy population

NASA Astrophysics Data System (ADS)

López, Leticia; Gastélum, Alfonso; Chan, Yuk Hin; Delmas, Patrice; Escorcia, Lilia; Márquez, Jorge

2014-11-01

Our goal is to obtain three-dimensional measurements of craniofacial morphology in a healthy population, using standard landmarks established by a physical-anthropology specialist and picked from computer reconstructions of the face of each subject. To do this, we designed a multi-stereo vision system that will be used to create a data base of human faces surfaces from a healthy population, for eventual applications in medicine, forensic sciences and anthropology. The acquisition process consists of obtaining the depth map information from three points of views, each depth map is obtained from a calibrated pair of cameras. The depth maps are used to build a complete, frontal, triangular-surface representation of the subject face. The triangular surface is used to locate the landmarks and the measurements are analyzed with a MATLAB script. The classification of the subjects was done with the aid of a specialist anthropologist that defines specific subject indices, according to the lengths, areas, ratios, etc., of the different structures and the relationships among facial features. We studied a healthy population and the indices from this population will be used to obtain representative averages that later help with the study and classification of possible pathologies.

A constrained Delaunay discretization method for adaptively meshing highly discontinuous geological media

NASA Astrophysics Data System (ADS)

Wang, Yang; Ma, Guowei; Ren, Feng; Li, Tuo

2017-12-01

A constrained Delaunay discretization method is developed to generate high-quality doubly adaptive meshes of highly discontinuous geological media. Complex features such as three-dimensional discrete fracture networks (DFNs), tunnels, shafts, slopes, boreholes, water curtains, and drainage systems are taken into account in the mesh generation. The constrained Delaunay triangulation method is used to create adaptive triangular elements on planar fractures. Persson's algorithm (Persson, 2005), based on an analogy between triangular elements and spring networks, is enriched to automatically discretize a planar fracture into mesh points with varying density and smooth-quality gradient. The triangulated planar fractures are treated as planar straight-line graphs (PSLGs) to construct piecewise-linear complex (PLC) for constrained Delaunay tetrahedralization. This guarantees the doubly adaptive characteristic of the resulted mesh: the mesh is adaptive not only along fractures but also in space. The quality of elements is compared with the results from an existing method. It is verified that the present method can generate smoother elements and a better distribution of element aspect ratios. Two numerical simulations are implemented to demonstrate that the present method can be applied to various simulations of complex geological media that contain a large number of discontinuities.

Single Null Negative Triangularity Tokamak for Power Handling

NASA Astrophysics Data System (ADS)

Kikuchi, Mitsuru; Medvedev, S.; Takizuka, T.; Sauter, O.; Merle, A.; Coda, S.; Chen, D.; Li, J. X.

2017-10-01

Power and particle control in fusion reactor is challenge and we proposed the negative triangularity tokamak (NTT) to eliminate ELM by operating L-mode edge with improved core confinement. The SN configuration has more flexibility in shaping by adopting rectangular-shaped TF coils. The limiting normalized beta is 3.56 with wall stabilization and 3.14 without wall. The vertical stability is assured under a reasonable control system. The wetted area on the divertor plates becomes wider in proportion to the larger major radius at the divertor strike points due to the NT configuration. In addition to the major-radius effect, the ``Flux Tune Expansion (FTE)'' is adopted to further reduce the heat load on the divertor plate by factor of 2.6 with a coil current 3 MA. L-mode edge also allows further increase in wetted area. The fusion power of 3 GW is deliverable only at normalized beta 2.1. Therefore this reactor may be operable stably against the serious MHD activities. The CD power for SS operation is 175 MW at Q = 17. AC operation is also possible option. A required HH factor is relatively modest H = 1.12.

Frequency-doubled microwave waveforms generation using a dual-polarization quadrature phase shift keying modulator driven by a single frequency radio frequency signal

NASA Astrophysics Data System (ADS)

Zhu, Zihang; Zhao, Shanghong; Li, Xuan; Qu, Kun; Lin, Tao

2018-01-01

A photonic approach to generate frequency-doubled microwave waveforms using an integrated dual-polarization quadrature phase shift keying (DP-QPSK) modulator driven by a sinusoidal radio frequency (RF) signal is proposed. By adjusting the dc bias points of the DP-QPSK modulator, the obtained second-order and six-order harmonics are in phase while the fourth-order harmonics are complementary when the orthogonal polarized outputs of the modulator are photodetected. After properly setting the modulation indices of the modulator, the amplitude of the second-order harmonic is 9 times of that of the six-order harmonic, indicating a frequency-doubled triangular waveform is generated. If a broadband 90° microwave phase shifter is attached after the photodetector (PD) to introduce a 90° phase shift, a frequency-doubled square waveform can be obtained after adjusting the amplitude of the second-order harmonic 3 times of that of the six-order harmonic. The proposal is first theoretically analyzed and then validated by simulation. Simulation results show that a 10 GHz triangular and square waveform sequences are successfully generated from a 5 GHz sinusoidal RF drive signal.

Thermoviscoplastic analysis of fibrous periodic composites using triangular subvolumes

NASA Technical Reports Server (NTRS)

Walker, Kevin P.; Freed, Alan D.; Jordan, Eric H.

1993-01-01

The nonlinear viscoplastic behavior of fibrous periodic composites is analyzed by discretizing the unit cell into triangular subvolumes. A set of these subvolumes can be configured by the analyst to construct a representation for the unit cell of a periodic composite. In each step of the loading history, the total strain increment at any point is governed by an integral equation which applies to the entire composite. A Fourier series approximation allows the incremental stresses and strains to be determined within a unit cell of the periodic lattice. The nonlinearity arising from the viscoplastic behavior of the constituent materials comprising the composite is treated as fictitious body force in the governing integral equation. Specific numerical examples showing the stress distributions in the unit cell of a fibrous tungsten/copper metal matrix composite under viscoplastic loading conditions are given. The stress distribution resulting in the unit cell when the composite material is subjected to an overall transverse stress loading history perpendicular to the fibers is found to be highly heterogeneous, and typical homogenization techniques based on treating the stress and strain distributions within the constituent phases as homogeneous result in large errors under inelastic loading conditions.

Thermoviscoplastic analysis of fibrous periodic composites by the use of triangular subvolumes

NASA Technical Reports Server (NTRS)

Walker, Kevin P.; Freed, Alan D.; Jordan, Eric H.

1994-01-01

The non-linear viscoplastic behavior of fibrous periodic composites is analyzed by discretizing the unit cell into triangular subvolumes. A set of these subvolumes can be configured by the analyst to construct a representation for the unit cell of a periodic composite. In each step of the loading history the total strain increment at any point is governed by an integral equation which applies to the entire composite. A Fourier series approximation allows the incremental stresses and strains to be determined within a unit cell of the periodic lattice. The non-linearity arising from the viscoplastic behavior of the constituent materials comprising the composite is treated as a fictitious body force in the governing integral equation. Specific numerical examples showing the stress distributions in the unit cell of a fibrous tungsten/copper metal-matrix composite under viscoplastic loading conditions are given. The stress distribution resulting in the unit cell when the composite material is subjected to an overall transverse stress loading history perpendicular to the fibers is found to be highly heterogeneous, and typical homogenization techniques based on treating the stress and strain distributions within the constituent phases as homogeneous result in large errors under inelastic loading conditions.

'My heart belongs to daddy'. Some reflections on the difference between generations as the organiser of the triangular structure of the mind.

PubMed

Sapisochin, G

1999-08-01

The author begins his paper with a historical review of the concept of the difference between generations, which is in his opinion a metaphorical transformation that underpins the three-dimensional functioning of the psychic apparatus by introducing a differentiating intergenerational space between subject and object. He postulates that at the point of intersection between the intersubjective and the intrapsychic the subject clings to the specific fragments of his parents' history that are consistent with a belief about himself and the oedipal couple in which intergenerational links are severed and infantile incestuous wishes are seen as fulfilled. Disavowal of this generation gap is considered to lead to failure of post-oedipal secondary identifications, resulting in disturbance of the triangular structuring of the mind and consequent impairment of the genesis of thought processes. These ideas are compared with related conceptions of other authors and illustrated, with an account of the associated transference/countertransference vicissitudes, by a clinical example of the constellation the author calls 'My heart belongs to daddy', which he sees as a way station in the negotiation of the female Oedipus complex.

Two-Year Outcomes from a Randomized Controlled Trial of Minimally Invasive Sacroiliac Joint Fusion vs. Non-Surgical Management for Sacroiliac Joint Dysfunction

PubMed Central

Swofford, John; Whang, Peter G.; Frank, Clay J.; Glaser, John A.; Limoni, Robert P.; Cher, Daniel J.; Wine, Kathryn D.; Sembrano, Jonathan N.

2016-01-01

Background Sacroiliac joint (SIJ) dysfunction is an important and underappreciated cause of chronic low back pain. Objective To prospectively and concurrently compare outcomes after surgical and non-surgical treatment for chronic SIJ dysfunction. Methods One hundred and forty-eight subjects with SIJ dysfunction were randomly assigned to minimally invasive SIJ fusion with triangular titanium implants (SIJF, n = 102) or non-surgical management (NSM, n = 46). SIJ pain (measured with a 100-point visual analog scale, VAS), disability (measured with Oswestry Disability Index, ODI) and quality of life scores were collected at baseline and at scheduled visits to 24 months. Crossover from non-surgical to surgical care was allowed after the 6-month study visit was complete. Improvements in continuous measures were compared using repeated measures analysis of variance. The proportions of subjects with clinical improvement (SIJ pain improvement ≥20 points, ODI ≥15 points) and substantial clinical benefit (SIJ pain improvement ≥25 points or SIJ pain rating ≤35, ODI ≥18.8 points) were compared. Results In the SIJF group, mean SIJ pain improved rapidly and was sustained (mean improvement of 55.4 points) at month 24. The 6-month mean change in the NSM group (12.2 points) was substantially smaller than that in the SIJF group (by 38.3 points, p<.0001 for superiority). By month 24, 83.1% and 82.0% received either clinical improvement or substantial clinical benefit in VAS SIJ pain score. Similarly, 68.2% and 65.9% had received clinical improvement or substantial clinical benefit in ODI score at month 24. In the NSM group, these proportions were <10% with non-surgical treatment only. Parallel changes were seen for EQ-5D and SF-36, with larger changes in the surgery group at 6 months compared to NSM. The rate of adverse events related to SIJF was low and only 3 subjects assigned to SIJF underwent revision surgery within the 24-month follow-up period. Conclusions In this Level 1 multicenter prospective randomized controlled trial, minimally invasive SIJF with triangular titanium implants provided larger improvements in pain, disability and quality of life compared to NSM. Improvements after SIJF persisted to 24 months. This study was approved by a local or central IRB before any subjects were enrolled. All patients provided study-specific informed consent prior to participation. PMID:27652199

Accidental degeneracy in photonic bands and topological phase transitions in two-dimensional core-shell dielectric photonic crystals.

PubMed

Xu, Lin; Wang, Hai-Xiao; Xu, Ya-Dong; Chen, Huan-Yang; Jiang, Jian-Hua

2016-08-08

A simple core-shell two-dimensional photonic crystal is studied where the triangular lattice symmetry and the C₆ point group symmetry give rich physics in accidental touching points of photonic bands. We systematically evaluate different types of accidental nodal points at the Brillouin zone center for transverse-magnetic harmonic modes when the geometry and permittivity of the core-shell material are continuously tuned. The accidental nodal points can have different dispersions and topological properties (i.e., Berry phases). These accidental nodal points can be the critical states lying between a topological phase and a normal phase of the photonic crystal. They are thus very important for the study of topological photonic states. We show that, without breaking time-reversal symmetry, by tuning the geometry of the core-shell material, a phase transition into the photonic quantum spin Hall insulator can be achieved. Here the "spin" is defined as the orbital angular momentum of a photon. We study the topological phase transition as well as the properties of the edge and bulk states and their application potentials in optics.

On the Use of the Beta Distribution in Probabilistic Resource Assessments

USGS Publications Warehouse

Olea, R.A.

2011-01-01

The triangular distribution is a popular choice when it comes to modeling bounded continuous random variables. Its wide acceptance derives mostly from its simple analytic properties and the ease with which modelers can specify its three parameters through the extremes and the mode. On the negative side, hardly any real process follows a triangular distribution, which from the outset puts at a disadvantage any model employing triangular distributions. At a time when numerical techniques such as the Monte Carlo method are displacing analytic approaches in stochastic resource assessments, easy specification remains the most attractive characteristic of the triangular distribution. The beta distribution is another continuous distribution defined within a finite interval offering wider flexibility in style of variation, thus allowing consideration of models in which the random variables closely follow the observed or expected styles of variation. Despite its more complex definition, generation of values following a beta distribution is as straightforward as generating values following a triangular distribution, leaving the selection of parameters as the main impediment to practically considering beta distributions. This contribution intends to promote the acceptance of the beta distribution by explaining its properties and offering several suggestions to facilitate the specification of its two shape parameters. In general, given the same distributional parameters, use of the beta distributions in stochastic modeling may yield significantly different results, yet better estimates, than the triangular distribution. ?? 2011 International Association for Mathematical Geology (outside the USA).

Dynamics and Control of Constrained Multibody Systems modeled with Maggi's equation: Application to Differential Mobile Robots Part I

NASA Astrophysics Data System (ADS)

Amengonu, Yawo H.; Kakad, Yogendra P.

2014-07-01

Quasivelocity techniques such as Maggi's and Boltzmann-Hamel's equations eliminate Lagrange multipliers from the beginning as opposed to the Euler-Lagrange method where one has to solve for the n configuration variables and the multipliers as functions of time when there are m nonholonomic constraints. Maggi's equation produces n second-order differential equations of which (n-m) are derived using (n-m) independent quasivelocities and the time derivative of the m kinematic constraints which add the remaining m second order differential equations. This technique is applied to derive the dynamics of a differential mobile robot and a controller which takes into account these dynamics is developed.

Augmented Lagrange Programming Neural Network for Localization Using Time-Difference-of-Arrival Measurements.

PubMed

Han, Zifa; Leung, Chi Sing; So, Hing Cheung; Constantinides, Anthony George

2017-08-15

A commonly used measurement model for locating a mobile source is time-difference-of-arrival (TDOA). As each TDOA measurement defines a hyperbola, it is not straightforward to compute the mobile source position due to the nonlinear relationship in the measurements. This brief exploits the Lagrange programming neural network (LPNN), which provides a general framework to solve nonlinear constrained optimization problems, for the TDOA-based localization. The local stability of the proposed LPNN solution is also analyzed. Simulation results are included to evaluate the localization accuracy of the LPNN scheme by comparing with the state-of-the-art methods and the optimality benchmark of Cramér-Rao lower bound.

Domain decomposition methods for nonconforming finite element spaces of Lagrange-type

NASA Technical Reports Server (NTRS)

Cowsar, Lawrence C.

1993-01-01

In this article, we consider the application of three popular domain decomposition methods to Lagrange-type nonconforming finite element discretizations of scalar, self-adjoint, second order elliptic equations. The additive Schwarz method of Dryja and Widlund, the vertex space method of Smith, and the balancing method of Mandel applied to nonconforming elements are shown to converge at a rate no worse than their applications to the standard conforming piecewise linear Galerkin discretization. Essentially, the theory for the nonconforming elements is inherited from the existing theory for the conforming elements with only modest modification by constructing an isomorphism between the nonconforming finite element space and a space of continuous piecewise linear functions.

Chest Wall Kinematics Using Triangular Cosserat Point Elements in Healthy and Neuromuscular Subjects.

PubMed

Solav, Dana; Meric, Henri; Rubin, M B; Pradon, Didier; Lofaso, Frédéric; Wolf, Alon

2017-08-01

Optoelectronic plethysmography (OEP) is a noninvasive method for assessing lung volume variations and the contributions of different anatomical compartments of the chest wall (CW) through measurements of the motion of markers attached to the CW surface. The present study proposes a new method for analyzing the local CW kinematics from OEP measurements based on the kinematics of triangular Cosserat point elements (TCPEs). 52 reflective markers were placed on the anterior CW to create a mesh of 78 triangles according to an anatomical model. Each triangle was characterized by a TCPE and its kinematics was described using four time-variant scalar TCPE parameters. The total CW volume ([Formula: see text]) and the contributions of its six compartments were also estimated, using the same markers. The method was evaluated using measurements of ten healthy subjects, nine patients with Pompe disease, and ten patients with Duchenne muscular dystrophy (DMD), during spontaneous breathing (SB) and vital capacity maneuvers (VC) in the supine position. TCPE parameters and compartmental volumes were compared with [Formula: see text] by computing the phase angles [Formula: see text] (for SB) and the correlation r (for VC) between them. Analysis of [Formula: see text] and r of the outward translation parameter [Formula: see text] of each TCPE revealed that for healthy subjects it provided similar results to those obtained by compartmental volumes, whereas for the neuromuscular patients the TCPE method was capable of detecting local asynchronous and paradoxical movements also in cases where they were undistinguished by volumes. Therefore, the TCPE approach provides additional information to OEP that may enhance its clinical evaluation capabilities.

Hidden topological constellations and polyvalent charges in chiral nematic droplets

NASA Astrophysics Data System (ADS)

Posnjak, Gregor; Čopar, Simon; Muševič, Igor

2017-02-01

Topology has an increasingly important role in the physics of condensed matter, quantum systems, material science, photonics and biology, with spectacular realizations of topological concepts in liquid crystals. Here we report on long-lived hidden topological states in thermally quenched, chiral nematic droplets, formed from string-like, triangular and polyhedral constellations of monovalent and polyvalent singular point defects. These topological defects are regularly packed into a spherical liquid volume and stabilized by the elastic energy barrier due to the helical structure and confinement of the liquid crystal in the micro-sphere. We observe, for the first time, topological three-dimensional point defects of the quantized hedgehog charge q=-2, -3. These higher-charge defects act as ideal polyvalent artificial atoms, binding the defects into polyhedral constellations representing topological molecules.

Discrete cosine and sine transforms generalized to honeycomb lattice

NASA Astrophysics Data System (ADS)

Hrivnák, Jiří; Motlochová, Lenka

2018-06-01

The discrete cosine and sine transforms are generalized to a triangular fragment of the honeycomb lattice. The honeycomb point sets are constructed by subtracting the root lattice from the weight lattice points of the crystallographic root system A2. The two-variable orbit functions of the Weyl group of A2, discretized simultaneously on the weight and root lattices, induce a novel parametric family of extended Weyl orbit functions. The periodicity and von Neumann and Dirichlet boundary properties of the extended Weyl orbit functions are detailed. Three types of discrete complex Fourier-Weyl transforms and real-valued Hartley-Weyl transforms are described. Unitary transform matrices and interpolating behavior of the discrete transforms are exemplified. Consequences of the developed discrete transforms for transversal eigenvibrations of the mechanical graphene model are discussed.

Hidden topological constellations and polyvalent charges in chiral nematic droplets

PubMed Central

Posnjak, Gregor; Čopar, Simon; Muševič, Igor

2017-01-01

Topology has an increasingly important role in the physics of condensed matter, quantum systems, material science, photonics and biology, with spectacular realizations of topological concepts in liquid crystals. Here we report on long-lived hidden topological states in thermally quenched, chiral nematic droplets, formed from string-like, triangular and polyhedral constellations of monovalent and polyvalent singular point defects. These topological defects are regularly packed into a spherical liquid volume and stabilized by the elastic energy barrier due to the helical structure and confinement of the liquid crystal in the micro-sphere. We observe, for the first time, topological three-dimensional point defects of the quantized hedgehog charge q=−2, −3. These higher-charge defects act as ideal polyvalent artificial atoms, binding the defects into polyhedral constellations representing topological molecules. PMID:28220770

7 CFR 810.1403 - Basis of determination.

Code of Federal Regulations, 2012 CFR

2012-01-01

... broken kernels, and foreign material that will pass through a 1.98 mm (5/64 inches) triangular-hole sieve... (5/64 inches) triangular-hole sieve. [57 FR 58971, Dec. 14, 1992] Grades and Grade Requirements ...

7 CFR 810.1403 - Basis of determination.

Code of Federal Regulations, 2014 CFR

2014-01-01

... broken kernels, and foreign material that will pass through a 1.98 mm (5/64 inches) triangular-hole sieve... (5/64 inches) triangular-hole sieve. [57 FR 58971, Dec. 14, 1992] Grades and Grade Requirements ...

7 CFR 810.1403 - Basis of determination.

Code of Federal Regulations, 2011 CFR

2011-01-01

... broken kernels, and foreign material that will pass through a 1.98 mm (5/64 inches) triangular-hole sieve... (5/64 inches) triangular-hole sieve. [57 FR 58971, Dec. 14, 1992] Grades and Grade Requirements ...

7 CFR 810.1403 - Basis of determination.

Code of Federal Regulations, 2013 CFR

2013-01-01

... broken kernels, and foreign material that will pass through a 1.98 mm (5/64 inches) triangular-hole sieve... (5/64 inches) triangular-hole sieve. [57 FR 58971, Dec. 14, 1992] Grades and Grade Requirements ...

Scaffolded DNA origami of a DNA tetrahedron molecular container.

PubMed

Ke, Yonggang; Sharma, Jaswinder; Liu, Minghui; Jahn, Kasper; Liu, Yan; Yan, Hao

2009-06-01

We describe a strategy of scaffolded DNA origami to design and construct 3D molecular cages of tetrahedron geometry with inside volume closed by triangular faces. Each edge of the triangular face is approximately 54 nm in dimension. The estimated total external volume and the internal cavity of the triangular pyramid are about 1.8 x 10(-23) and 1.5 x 10(-23) m(3), respectively. Correct formation of the tetrahedron DNA cage was verified by gel electrophoresis, atomic force microscopy, transmission electron microscopy, and dynamic light scattering techniques.

The formulation of dynamical contact problems with friction in the case of systems of rigid bodies and general discrete mechanical systems—Painlevé and Kane paradoxes revisited

NASA Astrophysics Data System (ADS)

Charles, Alexandre; Ballard, Patrick

2016-08-01

The dynamics of mechanical systems with a finite number of degrees of freedom (discrete mechanical systems) is governed by the Lagrange equation which is a second-order differential equation on a Riemannian manifold (the configuration manifold). The handling of perfect (frictionless) unilateral constraints in this framework (that of Lagrange's analytical dynamics) was undertaken by Schatzman and Moreau at the beginning of the 1980s. A mathematically sound and consistent evolution problem was obtained, paving the road for many subsequent theoretical investigations. In this general evolution problem, the only reaction force which is involved is a generalized reaction force, consistently with the virtual power philosophy of Lagrange. Surprisingly, such a general formulation was never derived in the case of frictional unilateral multibody dynamics. Instead, the paradigm of the Coulomb law applying to reaction forces in the real world is generally invoked. So far, this paradigm has only enabled to obtain a consistent evolution problem in only some very few specific examples and to suggest numerical algorithms to produce computational examples (numerical modeling). In particular, it is not clear what is the evolution problem underlying the computational examples. Moreover, some of the few specific cases in which this paradigm enables to write down a precise evolution problem are known to show paradoxes: the Painlevé paradox (indeterminacy) and the Kane paradox (increase in kinetic energy due to friction). In this paper, we follow Lagrange's philosophy and formulate the frictional unilateral multibody dynamics in terms of the generalized reaction force and not in terms of the real-world reaction force. A general evolution problem that governs the dynamics is obtained for the first time. We prove that all the solutions are dissipative; that is, this new formulation is free of Kane paradox. We also prove that some indeterminacy of the Painlevé paradox is fixed in this formulation.

Lagrange constraint neural network for audio varying BSS

NASA Astrophysics Data System (ADS)

Szu, Harold H.; Hsu, Charles C.

2002-03-01

Lagrange Constraint Neural Network (LCNN) is a statistical-mechanical ab-initio model without assuming the artificial neural network (ANN) model at all but derived it from the first principle of Hamilton and Lagrange Methodology: H(S,A)= f(S)- (lambda) C(s,A(x,t)) that incorporates measurement constraint C(S,A(x,t))= (lambda) ([A]S-X)+((lambda) 0-1)((Sigma) isi -1) using the vector Lagrange multiplier-(lambda) and a- priori Shannon Entropy f(S) = -(Sigma) i si log si as the Contrast function of unknown number of independent sources si. Szu et al. have first solved in 1997 the general Blind Source Separation (BSS) problem for spatial-temporal varying mixing matrix for the real world remote sensing where a large pixel footprint implies the mixing matrix [A(x,t)] necessarily fill with diurnal and seasonal variations. Because the ground truth is difficult to be ascertained in the remote sensing, we have thus illustrated in this paper, each step of the LCNN algorithm for the simulated spatial-temporal varying BSS in speech, music audio mixing. We review and compare LCNN with other popular a-posteriori Maximum Entropy methodologies defined by ANN weight matrix-[W] sigmoid-(sigma) post processing H(Y=(sigma) ([W]X)) by Bell-Sejnowski, Amari and Oja (BSAO) called Independent Component Analysis (ICA). Both are mirror symmetric of the MaxEnt methodologies and work for a constant unknown mixing matrix [A], but the major difference is whether the ensemble average is taken at neighborhood pixel data X's in BASO or at the a priori sources S variables in LCNN that dictates which method works for spatial-temporal varying [A(x,t)] that would not allow the neighborhood pixel average. We expected the success of sharper de-mixing by the LCNN method in terms of a controlled ground truth experiment in the simulation of variant mixture of two music of similar Kurtosis (15 seconds composed of Saint-Saens Swan and Rachmaninov cello concerto).

On the divergence of triangular and eccentric spherical sums of double Fourier series

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

Karagulyan, G A

We construct a continuous function on the torus with almost everywhere divergent triangular sums of double Fourier series. We also prove an analogous theorem for eccentric spherical sums. Bibliography: 14 titles.

Chemical lift-off of (11-22) semipolar GaN using periodic triangular cavities

NASA Astrophysics Data System (ADS)

Jeon, Dae-Woo; Lee, Seung-Jae; Jeong, Tak; Baek, Jong Hyeob; Park, Jae-Woo; Jang, Lee-Woon; Kim, Myoung; Lee, In-Hwan; Ju, Jin-Woo

2012-01-01

Chemical lift-off of (11-22) semipolar GaN using triangular cavities was investigated. The (11-22) semipolar GaN was grown using epitaxial lateral overgrowth by metal-organic chemical vapor deposition on m-plane sapphire, in such a way as to keep N terminated surface of c-plane GaN exposed in the cavities. After regrowing 300 μm thick (11-22) semipolar GaN by hydride vapor phase epitaxy for a free-standing (11-22) semipolar GaN substrate, the triangular cavities of the templates were chemically etched in molten KOH. The (000-2) plane in the triangular cavities can be etched in the [0002] direction with the high lateral etching rate of 196 μm/min. The resulting free-standing (11-22) semipolar GaN substrate was confirmed to be strain-free by the Raman analysis.

An approach to decision-making with triangular fuzzy reciprocal preference relations and its application

NASA Astrophysics Data System (ADS)

Meng, Fanyong

2018-02-01

Triangular fuzzy reciprocal preference relations (TFRPRs) are powerful tools to denoting decision-makers' fuzzy judgments, which permit the decision-makers to apply triangular fuzzy ratio rather than real numbers to express their judgements. Consistency analysis is one of the most crucial issues in preference relations that can guarantee the reasonable ranking order. However, all previous consistency concepts cannot well address this type of preference relations. Based on the operational laws on triangular fuzzy numbers, this paper introduces an additive consistency concept for TFRPRs by using quasi TFRPRs, which can be seen as a natural extension of the crisp case. Using this consistency concept, models to judging the additive consistency of TFRPRs and to estimating missing values in complete TFRPRs are constructed. Then, an algorithm to decision-making with TFRPRs is developed. Finally, two numerical examples are offered to illustrate the application of the proposed procedure, and comparison analysis is performed.

Polarizing beam splitter of deep-etched triangular-groove fused-silica gratings.

PubMed

Zheng, Jiangjun; Zhou, Changhe; Feng, Jijun; Wang, Bo

2008-07-15

We investigated the use of a deep-etched fused-silica grating with triangular-shaped grooves as a highly efficient polarizing beam splitter (PBS). A triangular-groove PBS grating is designed at a wavelength of 1550 nm to be used in optical communication. When it is illuminated in Littrow mounting, the transmitted TE- and TM-polarized waves are mainly diffracted in the minus-first and zeroth orders, respectively. The design condition is based on the average differences of the grating mode indices, which is verified by using rigorous coupled-wave analysis. The designed PBS grating is highly efficient over the C+L band range for both TE and TM polarizations (>97.68%). It is shown that such a triangular-groove PBS grating can exhibit a higher diffraction efficiency, a larger extinction ratio, and less reflection loss than the binary-phase fused-silica PBS grating.

Arrays of flow channels with heat transfer embedded in conducting walls

DOE PAGES

Bejan, A.; Almerbati, A.; Lorente, S.; ...

2016-04-20

Here we illustrate the free search for the optimal geometry of flow channel cross-sections that meet two objectives simultaneously: reduced resistances to heat transfer and fluid flow. The element cross section and the wall material are fixed, while the shape of the fluid flow opening, or the wetted perimeter is free to vary. Two element cross sections are considered, square and equilateral triangular. We find that the two objectives are best met when the solid wall thickness is uniform, i.e., when the wetted perimeters are square and triangular, respectively. In addition, we consider arrays of square elements and triangular elements,more » on the basis of equal mass flow rate per unit of array cross sectional area. The conclusion is that the array of triangular elements meets the two objectives better than the array of square elements.« less

Motions about a fixed point by hypergeometric functions: new non-complex analytical solutions and integration of the herpolhode

NASA Astrophysics Data System (ADS)

Mingari Scarpello, Giovanni; Ritelli, Daniele

2018-06-01

The present study highlights the dynamics of a body moving about a fixed point and provides analytical closed form solutions. Firstly, for the symmetrical heavy body, that is the Lagrange-Poisson case, we compute the second (precession, ψ ) and third (spin, φ) Euler angles in explicit and real form by means of multiple hypergeometric (Lauricella) functions. Secondly, releasing the weight assumption but adding the complication of the asymmetry, by means of elliptic integrals of third kind, we provide the precession angle ψ completing the treatment of the Euler-Poinsot case. Thirdly, by integrating the relevant differential equation, we reach the finite polar equation of a special motion trajectory named the herpolhode. Finally, we keep the symmetry of the first problem, but without weight, and take into account a viscous dissipation. The use of motion first integrals—adopted for the first two problems—is no longer practicable in this situation; therefore, the Euler equations, faced directly, are driving to particular occurrences of Bessel functions of order - 1/2.

Fractional spectral and pseudo-spectral methods in unbounded domains: Theory and applications

NASA Astrophysics Data System (ADS)

Khosravian-Arab, Hassan; Dehghan, Mehdi; Eslahchi, M. R.

2017-06-01

This paper is intended to provide exponentially accurate Galerkin, Petrov-Galerkin and pseudo-spectral methods for fractional differential equations on a semi-infinite interval. We start our discussion by introducing two new non-classical Lagrange basis functions: NLBFs-1 and NLBFs-2 which are based on the two new families of the associated Laguerre polynomials: GALFs-1 and GALFs-2 obtained recently by the authors in [28]. With respect to the NLBFs-1 and NLBFs-2, two new non-classical interpolants based on the associated- Laguerre-Gauss and Laguerre-Gauss-Radau points are introduced and then fractional (pseudo-spectral) differentiation (and integration) matrices are derived. Convergence and stability of the new interpolants are proved in detail. Several numerical examples are considered to demonstrate the validity and applicability of the basis functions to approximate fractional derivatives (and integrals) of some functions. Moreover, the pseudo-spectral, Galerkin and Petrov-Galerkin methods are successfully applied to solve some physical ordinary differential equations of either fractional orders or integer ones. Some useful comments from the numerical point of view on Galerkin and Petrov-Galerkin methods are listed at the end.

Passive remote sensing of altitude and optical depth of dust plumes using the oxygen A and B bands: First results from EPIC/DSCOVR at Lagrange-1 point

NASA Astrophysics Data System (ADS)

Xu, Xiaoguang; Wang, Jun; Wang, Yi; Zeng, Jing; Torres, Omar; Yang, Yuekui; Marshak, Alexander; Reid, Jeffrey; Miller, Steve

2017-07-01

We presented an algorithm for inferring aerosol layer height (ALH) and optical depth (AOD) over ocean surface from radiances in oxygen A and B bands measured by the Earth Polychromatic Imaging Camera (EPIC) on the Deep Space Climate Observatory (DSCOVR) orbiting at Lagrangian-1 point. The algorithm was applied to EPIC imagery of a 2 day dust outbreak over the North Atlantic Ocean. Retrieved ALHs and AODs were evaluated against counterparts observed by Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), Moderate Resolution Imaging Spectroradiometer, and Aerosol Robotic Network. The comparisons showed 71.5% of EPIC-retrieved ALHs were within ±0.5 km of those determined from CALIOP and 74.4% of EPIC AOD retrievals fell within a ± (0.1 + 10%) envelope of MODIS retrievals. This study demonstrates the potential of EPIC measurements for retrieving global aerosol height multiple times daily, which are essential for evaluating aerosol profile simulated in climate models and for better estimating aerosol radiative effects.

Total Transfer Capability Assessment Incorporating Corrective Controls for Transient Stability using TSCOPF

NASA Astrophysics Data System (ADS)

Hakim, Lukmanul; Kubokawa, Junji; Yorino, Naoto; Zoka, Yoshifumi; Sasaki, Yutaka

Advancements have been made towards inclusion of both static and dynamic security into transfer capability calculation. However, to the authors' knowledge, work on considering corrective controls into the calculation has not been reported yet. Therefore, we propose a Total Transfer Capability (TTC) assessment considering transient stability corrective controls. The method is based on the Newton interior point method for nonlinear programming and transfer capability is approached as a maximization of power transfer with both static and transient stability constraints are incorporated into our Transient Stability Constrained Optimal Power Flow (TSCOPF) formulation. An interconnected power system is simulated to be subjected to a severe unbalanced 3-phase 4-line to ground fault and following the fault, generator and load are shed in a pre-defined sequence to mimic actual corrective controls. In a deregulated electricity market, both generator companies and large load customers are encouraged to actively participate in maintaining power system stability as corrective controls upon agreement of compensation for being shed following a disturbance. Implementation of this proposal on the actual power system operation should be carried out through combining it with the existing transient stabilization controller system. Utilization of these corrective controls results in increasing TTC as suggested in our numerical simulation. As Lagrange multipliers can also describe sensitivity of both inequality and equality constraints to the objective function, then selection of which generator or load to be shed can be carried out on the basis of values of Lagrange multipliers of its respective generator's rotor angle stability and active power balance equation. Hence, the proposal in this paper can be utilized by system operator to assess the maximum TTC for specific loads and network conditions.

Quantum canonical ensemble: A projection operator approach

NASA Astrophysics Data System (ADS)

Magnus, Wim; Lemmens, Lucien; Brosens, Fons

2017-09-01

Knowing the exact number of particles N, and taking this knowledge into account, the quantum canonical ensemble imposes a constraint on the occupation number operators. The constraint particularly hampers the systematic calculation of the partition function and any relevant thermodynamic expectation value for arbitrary but fixed N. On the other hand, fixing only the average number of particles, one may remove the above constraint and simply factorize the traces in Fock space into traces over single-particle states. As is well known, that would be the strategy of the grand-canonical ensemble which, however, comes with an additional Lagrange multiplier to impose the average number of particles. The appearance of this multiplier can be avoided by invoking a projection operator that enables a constraint-free computation of the partition function and its derived quantities in the canonical ensemble, at the price of an angular or contour integration. Introduced in the recent past to handle various issues related to particle-number projected statistics, the projection operator approach proves beneficial to a wide variety of problems in condensed matter physics for which the canonical ensemble offers a natural and appropriate environment. In this light, we present a systematic treatment of the canonical ensemble that embeds the projection operator into the formalism of second quantization while explicitly fixing N, the very number of particles rather than the average. Being applicable to both bosonic and fermionic systems in arbitrary dimensions, transparent integral representations are provided for the partition function ZN and the Helmholtz free energy FN as well as for two- and four-point correlation functions. The chemical potential is not a Lagrange multiplier regulating the average particle number but can be extracted from FN+1 -FN, as illustrated for a two-dimensional fermion gas.

Ultrasonographic Diagnosis of Biliary Atresia Based on a Decision-Making Tree Model.

PubMed

Lee, So Mi; Cheon, Jung-Eun; Choi, Young Hun; Kim, Woo Sun; Cho, Hyun-Hae; Cho, Hyun-Hye; Kim, In-One; You, Sun Kyoung

2015-01-01

To assess the diagnostic value of various ultrasound (US) findings and to make a decision-tree model for US diagnosis of biliary atresia (BA). From March 2008 to January 2014, the following US findings were retrospectively evaluated in 100 infants with cholestatic jaundice (BA, n = 46; non-BA, n = 54): length and morphology of the gallbladder, triangular cord thickness, hepatic artery and portal vein diameters, and visualization of the common bile duct. Logistic regression analyses were performed to determine the features that would be useful in predicting BA. Conditional inference tree analysis was used to generate a decision-making tree for classifying patients into the BA or non-BA groups. Multivariate logistic regression analysis showed that abnormal gallbladder morphology and greater triangular cord thickness were significant predictors of BA (p = 0.003 and 0.001; adjusted odds ratio: 345.6 and 65.6, respectively). In the decision-making tree using conditional inference tree analysis, gallbladder morphology and triangular cord thickness (optimal cutoff value of triangular cord thickness, 3.4 mm) were also selected as significant discriminators for differential diagnosis of BA, and gallbladder morphology was the first discriminator. The diagnostic performance of the decision-making tree was excellent, with sensitivity of 100% (46/46), specificity of 94.4% (51/54), and overall accuracy of 97% (97/100). Abnormal gallbladder morphology and greater triangular cord thickness (> 3.4 mm) were the most useful predictors of BA on US. We suggest that the gallbladder morphology should be evaluated first and that triangular cord thickness should be evaluated subsequently in cases with normal gallbladder morphology.

Arthroscopically assisted reconstruction of triangular fibrocartilage complex foveal avulsion in the ulnar variance-positive patient.

PubMed

Kim, ByungSung; Yoon, Hong-Kee; Nho, Jae-Hwi; Park, Kang Hee; Park, Sung-Yong; Yoon, Jun-Hee; Song, Hyun Seok

2013-11-01

Our aim was to evaluate the clinical results of patients treated by arthroscopically assisted reconstruction of foveal avulsion injury of the triangular fibrocartilage complex (TFCC) using a suture anchor. We retrospectively reviewed the results of 15 patients (11 men and 4 women; mean age, 30.5 years) who underwent surgical procedures for the treatment of TFCC foveal avulsion at our hospital. The patients were followed up for a mean of 29 months. The patients had TFCC foveal avulsion caused by sprains (n = 8), falls (n = 4), playing baseball (n = 2), and a motor vehicle accident (n = 1). All the patients underwent magnetic resonance imaging. Radiographs obtained to assess ulnar variance (UV), ulnar-dorsal subluxation, and function of the wrist based on grip power; Disabilities of the Arm, Shoulder and Hand score; and Mayo wrist score were examined for all patients both preoperatively and postoperatively. On preoperative magnetic resonance imaging, TFCC foveal avulsion was observed in 13 of 15 cases. The mean UV value based on preoperative simple radiographic findings was 1.7 ± 1.0 mm, and dorsal subluxation at the distal ulna improved from 2.9 ± 3.0 mm to 0.2 ± 0.9 mm (P = .017). In all cases the distal radioulnar joint instability disappeared postoperatively. Grip power (compared with the uninvolved limb) was 79.3% preoperatively and 82.9% postoperatively (P = .086). The Disabilities of the Arm, Shoulder and Hand scores were 28.4 points preoperatively and 16.6 points postoperatively (P = .061). The Mayo wrist scores were excellent in 10 cases, good in 2, and fair in 3, and the mean score improved significantly from 64 points preoperatively to 84 points postoperatively (P = .007). Arthroscopic-assisted suture anchor reattachment of the TFCC in patients with traumatic TFCC foveal avulsion can prevent or reduce distal radioulnar joint instability and reduce pain even in chronic cases with positive UV. Level IV, therapeutic case series. Copyright © 2013 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Long-term prospective outcomes after minimally invasive trans-iliac sacroiliac joint fusion using triangular titanium implants.

PubMed

Darr, Emily; Meyer, S Craig; Whang, Peter G; Kovalsky, Don; Frank, Clay; Lockstadt, Harry; Limoni, Robert; Redmond, Andy; Ploska, Philip; Oh, Michael Y; Cher, Daniel; Chowdhary, Abhineet

2018-01-01

Minimally invasive sacroiliac joint fusion (SIJF) has become an increasingly accepted surgical option for chronic sacroiliac (SI) joint dysfunction, a prevalent cause of unremitting low back/buttock pain. The objective of this study was to report clinical and functional outcomes of SIJF using triangular titanium implants (TTI) in the treatment of chronic SI joint dysfunction due to degenerative sacroiliitis or sacroiliac joint (SIJ) disruption at 3 years postoperatively. A total of 103 subjects with SIJ dysfunction at 12 centers were treated with TTI in two prospective clinical trials (NCT01640353 and NCT01681004) and enrolled in this long-term follow-up study (NCT02270203). Subjects were evaluated in study clinics at study start and again at 3, 4, and 5 years. Mean (SD) preoperative SIJ pain score was 81.5, and mean preoperative Oswestry Disability Index (ODI) was 56.3. At 3 years, mean pain SIJ pain score decreased to 26.2 (a 55-point improvement from baseline, p <0.0001). At 3 years, mean ODI was 28.2 (a 28-point improvement from baseline, p <0.0001). In all, 82% of subjects were very satisfied with the procedure at 3 years. EuroQol-5D (EQ-5D) time trade-off index improved by 0.30 points ( p <0.0001). No adverse events definitely related to the study device or procedure were reported; one subject underwent revision surgery at year 3.7. SIJ pain contralateral to the originally treated side occurred in 15 subjects of whom four underwent contralateral SIJF. The proportion of subjects who were employed outside the home full- or part-time at 3 years decreased somewhat from baseline ( p =0.1814), and the proportion of subjects who would have the procedure again was lower at 3 years compared to earlier time points. In long-term (3-year) follow-up, minimally invasive trans-iliac SIJF with TTI was associated with improved pain, disability, and quality of life with relatively high satisfaction rates. Level II. SIJF with TTI.

Long-term prospective outcomes after minimally invasive trans-iliac sacroiliac joint fusion using triangular titanium implants

PubMed Central

Darr, Emily; Meyer, S Craig; Whang, Peter G; Kovalsky, Don; Frank, Clay; Lockstadt, Harry; Limoni, Robert; Redmond, Andy; Ploska, Philip; Oh, Michael Y; Cher, Daniel; Chowdhary, Abhineet

2018-01-01

Background Minimally invasive sacroiliac joint fusion (SIJF) has become an increasingly accepted surgical option for chronic sacroiliac (SI) joint dysfunction, a prevalent cause of unremitting low back/buttock pain. Objective The objective of this study was to report clinical and functional outcomes of SIJF using triangular titanium implants (TTI) in the treatment of chronic SI joint dysfunction due to degenerative sacroiliitis or sacroiliac joint (SIJ) disruption at 3 years postoperatively. Methods A total of 103 subjects with SIJ dysfunction at 12 centers were treated with TTI in two prospective clinical trials (NCT01640353 and NCT01681004) and enrolled in this long-term follow-up study (NCT02270203). Subjects were evaluated in study clinics at study start and again at 3, 4, and 5 years. Results Mean (SD) preoperative SIJ pain score was 81.5, and mean preoperative Oswestry Disability Index (ODI) was 56.3. At 3 years, mean pain SIJ pain score decreased to 26.2 (a 55-point improvement from baseline, p<0.0001). At 3 years, mean ODI was 28.2 (a 28-point improvement from baseline, p<0.0001). In all, 82% of subjects were very satisfied with the procedure at 3 years. EuroQol-5D (EQ-5D) time trade-off index improved by 0.30 points (p<0.0001). No adverse events definitely related to the study device or procedure were reported; one subject underwent revision surgery at year 3.7. SIJ pain contralateral to the originally treated side occurred in 15 subjects of whom four underwent contralateral SIJF. The proportion of subjects who were employed outside the home full- or part-time at 3 years decreased somewhat from baseline (p=0.1814), and the proportion of subjects who would have the procedure again was lower at 3 years compared to earlier time points. Conclusion In long-term (3-year) follow-up, minimally invasive trans-iliac SIJF with TTI was associated with improved pain, disability, and quality of life with relatively high satisfaction rates. Level of evidence Level II. Clinical relevance SIJF with TTI. PMID:29674852

DSCOVR Science Data and Retrospective Access

NASA Astrophysics Data System (ADS)

Rowland, W. F.; Codrescu, S.; Tilton, M.; Cartwright, J.; Redmon, R. J.; Loto'aniu, P. T. M.; Mccullough, H.; Denig, W. F.

2016-12-01

On July 27, 2016 the Deep Space Climate Observatory (DSCOVR) became the first operational satellite at the first Lagrange point (L1). This vantage, approximately one percent of the distance from the Earth to the Sun along the Earth-Sun line, means that DSCOVR data provide critical advanced warning of impending space weather events. As such, DSCOVR data are essential for forecasters, modelers, and the scientific community. The National Oceanic and Atmospheric Administration's National Centers for Environmental Information (NOAA/NCEI) archives the retrospective data and shares them with the public. We examine the data available, with a focus on some of the more interesting events that have occurred. We also discuss mechanisms created to facilitate search and access for those data, including a user-driven interface that allows one to dynamically generate plots and order relevant data of interest.

Rotational Properties of Jupiter Trojan 1173 Anchises

NASA Astrophysics Data System (ADS)

Chatelain, Joseph; Henry, Todd; French, Linda; Trilling, David

2015-11-01

Anchises (1173) is a large Trojan asteroid librating about Jupiter’s L5 Lagrange point. Here we examine its rotational and lightcurve properties by way of data collected over a 3.5 year observing campaign. The length of the campaign means that data were gathered for more than a quarter of Anchises' full orbital revolution which allows for accurate determinations of pole orientation and bulk shape properties for the asteroid that can then be compared to results of previous work (i.e. French 1987, Horner et al. 2012). In addition to light curves, photometric data taken during this campaign could potentially detect color differences between hemispheres as the viewing geometry changes over time. Understanding these details about a prominent member of the Jupiter Trojans may help us better understand the history of this fascinating and important group of asteroids.

Real-time Kp predictions from ACE real time solar wind

NASA Astrophysics Data System (ADS)

Detman, Thomas; Joselyn, Joann

1999-06-01

The Advanced Composition Explorer (ACE) spacecraft provides nearly continuous monitoring of solar wind plasma, magnetic fields, and energetic particles from the Sun-Earth L1 Lagrange point upstream of Earth in the solar wind. The Space Environment Center (SEC) in Boulder receives ACE telemetry from a group of international network of tracking stations. One-minute, and 1-hour averages of solar wind speed, density, temperature, and magnetic field components are posted on SEC's World Wide Web page within 3 to 5 minutes after they are measured. The ACE Real Time Solar Wind (RTSW) can be used to provide real-time warnings and short term forecasts of geomagnetic storms based on the (traditional) Kp index. Here, we use historical data to evaluate the performance of the first real-time Kp prediction algorithm to become operational.

Prevalence of triangular fibrocartilage complex abnormalities regardless of symptoms rise with age: systematic review and pooled analysis.

PubMed

Chan, Jimmy J; Teunis, Teun; Ring, David

2014-12-01

Triangular fibrocartilage complex abnormalities seem to be more common with age, but the degree to which this is so, and the degree to which the presence of an abnormality is associated with symptoms, are topics of controversy. We wished to perform a systematic review to determine the prevalence of triangular fibrocartilage complex abnormalities, and to determine if the prevalence of abnormalities are greater with increasing age. In addition, we stratified age groups based on symptoms. We searched MEDLINE, EMBASE, and the Cochrane Library through August 15, 2013. Studies that reported triangular fibrocartilage complex abnormalities by age were included. Fifteen studies including 977 wrists met our criteria and reported a total of 368 (38%) triangular fibrocartilage complex abnormalities. Eight studies included symptomatic patients; the remainder studied cadavers (six studies) or asymptomatic volunteers (one study). Patients were divided into four age groups (< 30, 30-49, 50-69, and 70 years and older) for pooled analysis, comparing the proportions of patients with and without abnormalities between groups using chi-square analysis. We also evaluated the proportions after stratifying each age group by symptoms. Overall, the prevalence of triangular fibrocartilage complex abnormalities increased with age, from 27% (80/301) in patients younger than 30 years to 49% (130/265) in patients 70 years and older (p < 0.001), odds ratio (OR), 2.7, 95% CI, 1.9-3.8 (p < 0.001). In asymptomatic patients, triangular fibrocartilage complex prevalence abnormality increased from 15% (24/159) to 49% (129/263) in the same age groups (p < 0.001), OR, 5.4, 95% CI, 3.3-8.9 (p < 0.001). For symptomatic patients prevalence ranged from 39% (56/142) to 70% (14/20) in patients between 50 and 69 years old (p < 0.034), OR, 3.6, 95% CI, 1.3-9.9 (p < 0.014). Triangular fibrocartilage complex abnormalities are common in symptomatic and asymptomatic wrists, and they are increasingly common with age. As in all situations where abnormalities are so common that they may be incidental, we need (1) a reliable and accurate method for determining whether these abnormalities are the cause of symptoms; and (2) evidence that treatment of these abnormalities improves symptoms better than placebo. Level III, prognostic study. See the Instructions for Authors for a complete description of levels of evidence.

Chevron Defect at the Intersection of Grain Boundaries with Free Surfaces in Au

NASA Astrophysics Data System (ADS)

Radetic, T.; Lançon, F.; Dahmen, U.

2002-08-01

We have identified a new defect at the intersection between grain boundaries and surfaces in Au using atomic resolution transmission electron microscopy. At the junction line of 90° <110> tilt grain boundaries of (110)-(001) orientation with the free surface, a small segment of the grain boundary, about 1nm in length, dissociates into a triangular region with a chevronlike stacking disorder and a distorted hcp structure. The structure and stability of these defects are confirmed by atomistic simulations, and we point out the relationship with the one-dimensional incommensurate structure of the grain boundary.

Sandia Unstructured Triangle Tabular Interpolation Package v 0.1 beta

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

2013-09-24

The software interpolates tabular data, such as for equations of state, provided on an unstructured triangular grid. In particular, interpolation occurs in a two dimensional space by looking up the triangle in which the desired evaluation point resides and then performing a linear interpolation over the n-tuples associated with the nodes of the chosen triangle. The interface to the interpolation routines allows for automated conversion of units from those tabulated to the desired output units. when multiple tables are included in a data file, new tables may be generated by on-the-fly mixing of the provided tables

A 3D front tracking method on a CPU/GPU system

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

Bo, Wurigen; Grove, John

2011-01-21

We describe the method to port a sequential 3D interface tracking code to a GPU with CUDA. The interface is represented as a triangular mesh. Interface geometry properties and point propagation are performed on a GPU. Interface mesh adaptation is performed on a CPU. The convergence of the method is assessed from the test problems with given velocity fields. Performance results show overall speedups from 11 to 14 for the test problems under mesh refinement. We also briefly describe our ongoing work to couple the interface tracking method with a hydro solver.

On the photo-gravitational restricted four-body problem with variable mass

NASA Astrophysics Data System (ADS)

Mittal, Amit; Agarwal, Rajiv; Suraj, Md Sanam; Arora, Monika

2018-05-01

This paper deals with the photo-gravitational restricted four-body problem (PR4BP) with variable mass. Following the procedure given by Gascheau (C. R. 16:393-394, 1843) and Routh (Proc. Lond. Math. Soc. 6:86-97, 1875), the conditions of linear stability of Lagrange triangle solution in the PR4BP are determined. The three radiating primaries having masses m1, m2 and m3 in an equilateral triangle with m2=m3 will be stable as long as they satisfy the linear stability condition of the Lagrangian triangle solution. We have derived the equations of motion of the mentioned problem and observed that there exist eight libration points for a fixed value of parameters γ (m at time t/m at initial time, 0<γ≤1 ), α (the proportionality constant in Jeans' law (Astronomy and Cosmogony, Cambridge University Press, Cambridge, 1928), 0≤α≤2.2), the mass parameter μ=0.005 and radiation parameters qi, (0< qi≤1, i=1, 2, 3). All the libration points are non-collinear if q2≠ q3. It has been observed that the collinear and out-of-plane libration points also exist for q2=q3. In all the cases, each libration point is found to be unstable. Further, zero velocity curves (ZVCs) and Newton-Raphson basins of attraction are also discussed.

An Introduction to Lagrangian Differential Calculus.

ERIC Educational Resources Information Center

Schremmer, Francesca; Schremmer, Alain

1990-01-01

Illustrates how Lagrange's approach applies to the differential calculus of polynomial functions when approximations are obtained. Discusses how to obtain polynomial approximations in other cases. (YP)

Comments on "The multisynapse neural network and its application to fuzzy clustering".

PubMed

Yu, Jian; Hao, Pengwei

2005-05-01

In the above-mentioned paper, Wei and Fahn proposed a neural architecture, the multisynapse neural network, to solve constrained optimization problems including high-order, logarithmic, and sinusoidal forms, etc. As one of its main applications, a fuzzy bidirectional associative clustering network (FBACN) was proposed for fuzzy-partition clustering according to the objective-functional method. The connection between the objective-functional-based fuzzy c-partition algorithms and FBACN is the Lagrange multiplier approach. Unfortunately, the Lagrange multiplier approach was incorrectly applied so that FBACN does not equivalently minimize its corresponding constrained objective-function. Additionally, Wei and Fahn adopted traditional definition of fuzzy c-partition, which is not satisfied by FBACN. Therefore, FBACN can not solve constrained optimization problems, either.

Spherical Pendulum Small Oscillations for Slewing Crane Motion

PubMed Central

Perig, Alexander V.; Stadnik, Alexander N.; Deriglazov, Alexander I.

2014-01-01

The present paper focuses on the Lagrange mechanics-based description of small oscillations of a spherical pendulum with a uniformly rotating suspension center. The analytical solution of the natural frequencies' problem has been derived for the case of uniform rotation of a crane boom. The payload paths have been found in the inertial reference frame fixed on earth and in the noninertial reference frame, which is connected with the rotating crane boom. The numerical amplitude-frequency characteristics of the relative payload motion have been found. The mechanical interpretation of the terms in Lagrange equations has been outlined. The analytical expression and numerical estimation for cable tension force have been proposed. The numerical computational results, which correlate very accurately with the experimental observations, have been shown. PMID:24526891

Variational tricomplex of a local gauge system, Lagrange structure and weak Poisson bracket

NASA Astrophysics Data System (ADS)

Sharapov, A. A.

2015-09-01

We introduce the concept of a variational tricomplex, which is applicable both to variational and nonvariational gauge systems. Assigning this tricomplex with an appropriate symplectic structure and a Cauchy foliation, we establish a general correspondence between the Lagrangian and Hamiltonian pictures of one and the same (not necessarily variational) dynamics. In practical terms, this correspondence allows one to construct the generating functional of a weak Poisson structure starting from that of a Lagrange structure. As a byproduct, a covariant procedure is proposed for deriving the classical BRST charge of the BFV formalism by a given BV master action. The general approach is illustrated by the examples of Maxwell’s electrodynamics and chiral bosons in two dimensions.

Time and Energy, Exploring Trajectory Options Between Nodes in Earth-Moon Space

NASA Technical Reports Server (NTRS)

Martinez, Roland; Condon, Gerald; Williams, Jacob

2012-01-01

The Global Exploration Roadmap (GER) was released by the International Space Exploration Coordination Group (ISECG) in September of 2011. It describes mission scenarios that begin with the International Space Station and utilize it to demonstrate necessary technologies and capabilities prior to deployment of systems into Earth-Moon space. Deployment of these systems is an intermediate step in preparation for more complex deep space missions to near-Earth asteroids and eventually Mars. In one of the scenarios described in the GER, "Asteroid Next", there are activities that occur in Earth-Moon space at one of the Earth-Moon Lagrange (libration) points. In this regard, the authors examine the possible role of an intermediate staging point in an effort to illuminate potential trajectory options for conducting missions in Earth-Moon space of increasing duration, ultimately leading to deep space missions. This paper will describe several options for transits between Low Earth Orbit (LEO) and the libration points, transits between libration points, and transits between the libration points and interplanetary trajectories. The solution space provided will be constrained by selected orbital mechanics design techniques and physical characteristics of hardware to be used in both crewed missions and uncrewed missions. The relationships between time and energy required to transfer hardware between these locations will provide a better understanding of the potential trade-offs mission planners could consider in the development of capabilities, individual missions, and mission series in the context of the ISECG GER.

DETAIL VIEW OF LARGE BORE HOLE, SHOWING TRIANGULAR SHAPE FORMED ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DETAIL VIEW OF LARGE BORE HOLE, SHOWING TRIANGULAR SHAPE FORMED BY CHISEL METHOD OF DRILLING - Granite Hill Plantation, Quarry No. 3, South side of State Route 16, 1.3 miles northeast east of Sparta, Sparta, Hancock County, GA

Theoretical characteristics in supersonic flow of two types of control surfaces on triangular wings

NASA Technical Reports Server (NTRS)

Tucker, Warren A; Nelson, Robert L

1949-01-01

Methods based on the linearized theory for supersonic flow were used to find the characteristics of two types of control surfaces on thin triangular wings. The first type, the constant-chord partial-span flap, was considered to extend either outboard from the center of the wing or inboard from the wing tip. The second type, the full-triangular-tip flap, was treated only for the case in which the Mach number component normal to the leading edge is supersonic. For each type, expressions were found for the lift, rolling-moment, pitching-moment, and hinge-moment characteristics.

Structured background grids for generation of unstructured grids by advancing front method

NASA Technical Reports Server (NTRS)

Pirzadeh, Shahyar

1991-01-01

A new method of background grid construction is introduced for generation of unstructured tetrahedral grids using the advancing-front technique. Unlike the conventional triangular/tetrahedral background grids which are difficult to construct and usually inadequate in performance, the new method exploits the simplicity of uniform Cartesian meshes and provides grids of better quality. The approach is analogous to solving a steady-state heat conduction problem with discrete heat sources. The spacing parameters of grid points are distributed over the nodes of a Cartesian background grid by interpolating from a few prescribed sources and solving a Poisson equation. To increase the control over the grid point distribution, a directional clustering approach is used. The new method is convenient to use and provides better grid quality and flexibility. Sample results are presented to demonstrate the power of the method.

Half-metallic ferromagnetism in substitutionally doped boronitrene

NASA Astrophysics Data System (ADS)

Ukpong, A. M.; Chetty, N.

2012-11-01

We perform first-principles molecular dynamics simulations to investigate the magnetoelectronic response of substitutionally doped boronitrene to thermal excitation. We show that the local geometry, size, and edge termination of the substitutional complexes of boron, carbon, or nitrogen determine the thermodynamic stability of the monolayer. We find that hexagonal boron or triangular carbon clusters induce finite magnetic moments with 100% spin-polarized Fermi-level electrons in boronitrene. In such carbon substitutions, the spontaneous magnetic moment increases with the size of the embedded carbon cluster, and results in half-metallic ferrimagnetism above 750 K with a corresponding Curie point of 1250 K, above which the magnetization density vanishes. We predict an ultrahigh temperature half-metallic ferromagnetic phase in impurity-free boronitrene, when any three nearest-neighbor nitrogen atoms are substituted with boron, with unquenched magnetic moment up to its melting point.

Motion systems providing three or four degrees of freedom

NASA Technical Reports Server (NTRS)

Chou, Richard C. (Inventor)

1982-01-01

A motion system is provided by a platform generally parallel to a base and connected thereto by a column and powered and controlled extensible members, at least three of which are connected between distributed points around the column. In a three degree of freedom device, the column is conical, rigidly supported at its base with a universal joint at its top. The points of attachment define triangles in the base and in the platform surrounding the column with one extensible member connected between each. In the four degree of freedom version, the column is modified by making it effectively a column which is pivoted or guided at the base or contains an extensible member, preferably retains its triangular shape and its universal joint connection to the platform at its apex. For stability four powered and controlled extensible members are provided between points in the base and platform distributed around the column, a preferred pattern of arrangement being a square with the column at the center.

[Arthroscopically assisted transcapsular refixation of the triangular fibrocartilage complex of the wrist].

PubMed

Pillukat, T; Fuhrmann, R A; Windolf, J; van Schoonhoven, J

2016-08-01

Refixation of the triangular fibrocartilage complex (TFCC) to the ulnar capsule of the wrist. Distal TFCC tears without instability, proximal TFCC intact. Loose ulnar TFCC attachment without tear or instability. Peripheral TFCC tears with instability of the distal radioulnar joint (DRUJ). Complex or proximal tears of the TFCC. Isolated, central degenerative tears without healing potential. Arthroscopically guided, minimally invasive suture of the TFCC to the base of the sixth extensor compartment. Above elbow plaster splint, 70° flexion of the elbow joint, 45° supination for 6 weeks. Skin suture removal after 2 weeks. No physiotherapy to extend pronation and supination during the first 3 months. In an ongoing long-term study, 7 of 31 patients who underwent transcapsular refixation of the TFCC between 1 January 2003 and 31 December 2010 were evaluated after an average follow-up interval of 116 ± 34 months (range 68-152 months). All patients demonstrated an almost nearly unrestricted range of wrist motion and grip strength compared to the unaffected side. All distal radioulnar joints were stable. On the visual analogue scale (VAS 0-10), pain at rest was 1 ± 1 (range 0-2) and pain during exercise 2 ± 2 (range 0-5); the DASH score averaged 10 ± 14 points (range 0-39 points). All patients were satisfied. The modified Mayo wrist score showed four excellent, two good, and one fair result. These results correspond to the results of other series. Transcapsular refixation is a reliable, technically simple procedure in cases with ulnar-sided TFCC tears without instability leading to good results.

3D face analysis by using Mesh-LBP feature

NASA Astrophysics Data System (ADS)

Wang, Haoyu; Yang, Fumeng; Zhang, Yuming; Wu, Congzhong

2017-11-01

Objective: Face Recognition is one of the widely application of image processing. Corresponding two-dimensional limitations, such as the pose and illumination changes, to a certain extent restricted its accurate rate and further development. How to overcome the pose and illumination changes and the effects of self-occlusion is the research hotspot and difficulty, also attracting more and more domestic and foreign experts and scholars to study it. 3D face recognition fusing shape and texture descriptors has become a very promising research direction. Method: Our paper presents a 3D point cloud based on mesh local binary pattern grid (Mesh-LBP), then feature extraction for 3D face recognition by fusing shape and texture descriptors. 3D Mesh-LBP not only retains the integrity of the 3D geometry, is also reduces the need for recognition process of normalization steps, because the triangle Mesh-LBP descriptor is calculated on 3D grid. On the other hand, in view of multi-modal consistency in face recognition advantage, construction of LBP can fusing shape and texture information on Triangular Mesh. In this paper, some of the operators used to extract Mesh-LBP, Such as the normal vectors of the triangle each face and vertex, the gaussian curvature, the mean curvature, laplace operator and so on. Conclusion: First, Kinect devices obtain 3D point cloud face, after the pretreatment and normalization, then transform it into triangular grid, grid local binary pattern feature extraction from face key significant parts of face. For each local face, calculate its Mesh-LBP feature with Gaussian curvature, mean curvature laplace operator and so on. Experiments on the our research database, change the method is robust and high recognition accuracy.

Triangular Titanium Implants for Minimally Invasive Sacroiliac Joint Fusion: A Prospective Study.

PubMed

Duhon, Bradley S; Cher, Daniel J; Wine, Kathryn D; Kovalsky, Don A; Lockstadt, Harry

2016-05-01

Study Design Prospective multicenter single-arm interventional clinical trial. Objective To determine the degree of improvement in sacroiliac (SI) joint pain, disability related to SI joint pain, and quality of life in patients with SI joint dysfunction who undergo minimally invasive SI joint fusion using triangular-shaped titanium implants. Methods Subjects (n = 172) underwent minimally invasive SI joint fusion between August 2012 and January 2014 and completed structured assessments preoperatively and at 1, 3, 6, and 12 months postoperatively, including a 100-mm SI joint and back pain visual analog scale (VAS), Oswestry Disability Index (ODI), Short Form-36 (SF-36), and EuroQOL-5D. Patient satisfaction with surgery was assessed at 6 and 12 months. Results Mean SI joint pain improved from 79.8 at baseline to 30.0 and 30.4 at 6 and 12 months, respectively (mean improvements of 49.9 and 49.1 points, p < 0.0001 each). Mean ODI improved from 55.2 at baseline to 32.5 and 31.4 at 6 and 12 months (improvements of 22.7 and 23.9 points, p < 0.0001 each). SF-36 physical component summary improved from 31.7 at baseline to 40.2 and 40.3 at 6 and 12 months (p < 0.0001). At 6 and 12 months, 93 and 87% of subjects, respectively, were somewhat or very satisfied and 92 and 91%, respectively, would have the procedure again. Conclusions Minimally invasive SI joint fusion resulted in improvement of pain, disability, and quality of life in patients with SI joint dysfunction due to degenerative sacroiliitis and SI joint disruption.

Triangular Titanium Implants for Minimally Invasive Sacroiliac Joint Fusion: A Prospective Study

PubMed Central

Duhon, Bradley S.; Cher, Daniel J.; Wine, Kathryn D.; Kovalsky, Don A.; Lockstadt, Harry

2015-01-01

Study Design Prospective multicenter single-arm interventional clinical trial. Objective To determine the degree of improvement in sacroiliac (SI) joint pain, disability related to SI joint pain, and quality of life in patients with SI joint dysfunction who undergo minimally invasive SI joint fusion using triangular-shaped titanium implants. Methods Subjects (n = 172) underwent minimally invasive SI joint fusion between August 2012 and January 2014 and completed structured assessments preoperatively and at 1, 3, 6, and 12 months postoperatively, including a 100-mm SI joint and back pain visual analog scale (VAS), Oswestry Disability Index (ODI), Short Form-36 (SF-36), and EuroQOL-5D. Patient satisfaction with surgery was assessed at 6 and 12 months. Results Mean SI joint pain improved from 79.8 at baseline to 30.0 and 30.4 at 6 and 12 months, respectively (mean improvements of 49.9 and 49.1 points, p < 0.0001 each). Mean ODI improved from 55.2 at baseline to 32.5 and 31.4 at 6 and 12 months (improvements of 22.7 and 23.9 points, p < 0.0001 each). SF-36 physical component summary improved from 31.7 at baseline to 40.2 and 40.3 at 6 and 12 months (p < 0.0001). At 6 and 12 months, 93 and 87% of subjects, respectively, were somewhat or very satisfied and 92 and 91%, respectively, would have the procedure again. Conclusions Minimally invasive SI joint fusion resulted in improvement of pain, disability, and quality of life in patients with SI joint dysfunction due to degenerative sacroiliitis and SI joint disruption. PMID:27099817

Langley Full-scale-tunnel Investigation of Maximum Lift and Stability Characteristics of an Airplane Having Approximately Triangular Plan Form (DM-1 Glider)

NASA Technical Reports Server (NTRS)

Lovell, J Calvin; Wilson, Herbert A JR

1947-01-01

An investigation of the DM-1 Glider, which had approximately triangular plan form, an aspect ratio of 1.8 and a 60 degree sweptback leading edge, has been conducted in the Langley full-scale tunnel. The investigation consisted of the determination of the separate effects of the following modifications made to the glider on its maximum lift and stability characteristics: (a) installation of sharp leading edges over the inboard semispan of the wing, (b) removal of the vertical fin, (c) sealing of the elevon control-balance slots, (d) installation of redesigned thin vertical surfaces, (e) installation of faired sharp leading edges, and (f) installation of canopy. The maximum lift coefficient of the DM-1 glider was increased from 0.61 to 1.01 by the installation of semispan sharp leading edges, and from 1.01 to 1.24 by the removal of the vertical fin and sealing of the elevon control-balance slots. The highest maximum lift coefficient (1.32) was obtained when the faired sharp leading edges and the thin vertical surfaces were attached to the glider. The original DM-1 glider was longitudinally stable. The semispan sharp leading edges shifted the neutral point forward approximately 3 percent of the root chord at moderate lift coefficients, and the glider configuration with these sharp leading edges attached was longitudinally unstable, for the assumed center-of-gravity location, at lift coefficients above 0.73. Sealing the elevon control-balance slots and installing the faired sharp leading edges, the thin vertical surfaces, and the canopy shifted the neutral point forward approximately 8 percent of the root chord.

Mathematical Investigation of Fluid Flow, Mass Transfer, and Slag-steel Interfacial Behavior in Gas-stirred Ladles

NASA Astrophysics Data System (ADS)

Cao, Qing; Nastac, Laurentiu

2018-06-01

In this study, the Euler-Euler and Euler-Lagrange modeling approaches were applied to simulate the multiphase flow in the water model and gas-stirred ladle systems. Detailed comparisons of the computational and experimental results were performed to establish which approach is more accurate for predicting the gas-liquid multiphase flow phenomena. It was demonstrated that the Euler-Lagrange approach is more accurate than the Euler-Euler approach. The Euler-Lagrange approach was applied to study the effects of the free surface setup, injected bubble size, gas flow rate, and slag layer thickness on the slag-steel interaction and mass transfer behavior. Detailed discussions on the flat/non-flat free surface assumption were provided. Significant inaccuracies in the prediction of the surface fluid flow characteristics were found when the flat free surface was assumed. The variations in the main controlling parameters (bubble size, gas flow rate, and slag layer thickness) and their potential impact on the multiphase fluid flow and mass transfer characteristics (turbulent intensity, mass transfer rate, slag-steel interfacial area, flow patterns, etc.,) in gas-stirred ladles were quantitatively determined to ensure the proper increase in the ladle refining efficiency. It was revealed that by injecting finer bubbles as well as by properly increasing the gas flow rate and the slag layer thickness, the ladle refining efficiency can be enhanced significantly.

Interpreting medium ring canonical conformers by a triangular plane tessellation of the macrocycle

NASA Astrophysics Data System (ADS)

Khalili, Pegah; Barnett, Christopher B.; Naidoo, Kevin J.

2013-05-01

Cyclic conformational coordinates are essential for the distinction of molecular ring conformers as the use of Cremer-Pople coordinates have illustrated for five- and six-membered rings. Here, by tessellating medium rings into triangular planes and using the relative angles made between triangular planes we are able to assign macrocyclic pucker conformations into canonical pucker conformers such as chairs, boats, etc. We show that the definition is straightforward compared with other methods popularly used for small rings and that it is computationally simple to implement for complex macrocyclic rings. These cyclic conformational coordinates directly couple to the motion of individual nodes of a ring. Therefore, they are useful for correlating the physical properties of macrocycles with their ring pucker and measuring the dynamic ring conformational behavior. We illustrate the triangular tessellation, assignment, and pucker analysis on 7- and 8-membered rings. Sets of canonical states are given for cycloheptane and cyclooctane that have been previously experimentally analysed.

Arthroscopic assisted tendon reconstruction for triangular fibrocartilage complex irreparable tears.

PubMed

Luchetti, R; Atzei, A

2017-05-01

We report our 11-year experience of performing arthroscopically assisted triangular fibrocartilage complex reconstruction in the treatment of chronic distal radio-ulnar joint instability resulting from irreparable triangular fibrocartilage complex injuries. Eleven patients were treated. Three skin incisions were made in order to create radial and ulna tunnels for passage of the tendon graft, which is used to reconstruct the dorsal and palmar radio-ulnar ligaments, under fluoroscopic and arthroscopic guidance. At a mean follow-up of 68 months all but one had a stable distal radio-ulnar joint. Pain and grip strength, Mayo wrist score, Disability of the Arm Hand and Shoulder and patient-rated wrist and hand evaluation scores improved. The ranges of forearm rotation remained largely unchanged. Complications included an early tendon graft tear, two late-onset graft ruptures, one ulna styloid fracture during surgery and persistent wrist discomfort during forearm rotation requiring tendon graft revision in one case. An arthroscopic assisted approach for triangular fibrocartilage complex reconstruction appears safe and produces comparable results with the open technique. IV.

Topological magnon bands and unconventional thermal Hall effect on the frustrated honeycomb and bilayer triangular lattice.

PubMed

Owerre, S A

2017-09-27

In the conventional ferromagnetic systems, topological magnon bands and thermal Hall effect are due to the Dzyaloshinskii-Moriya interaction (DMI). In principle, however, the DMI is either negligible or it is not allowed by symmetry in some quantum magnets. Therefore, we expect that topological magnon features will not be present in those systems. In addition, quantum magnets on the triangular-lattice are not expected to possess topological features as the DMI or spin-chirality cancels out due to equal and opposite contributions from adjacent triangles. Here, however, we predict that the isomorphic frustrated honeycomb-lattice and bilayer triangular-lattice antiferromagnetic system will exhibit topological magnon bands and topological thermal Hall effect in the absence of an intrinsic DMI. These unconventional topological magnon features are present as a result of magnetic-field-induced non-coplanar spin configurations with nonzero scalar spin chirality. The relevance of the results to realistic bilayer triangular antiferromagnetic materials are discussed.

On Modeling and Analysis of MIMO Wireless Mesh Networks with Triangular Overlay Topology

DOE PAGES

Cao, Zhanmao; Wu, Chase Q.; Zhang, Yuanping; ...

2015-01-01

Multiple input multiple output (MIMO) wireless mesh networks (WMNs) aim to provide the last-mile broadband wireless access to the Internet. Along with the algorithmic development for WMNs, some fundamental mathematical problems also emerge in various aspects such as routing, scheduling, and channel assignment, all of which require an effective mathematical model and rigorous analysis of network properties. In this paper, we propose to employ Cartesian product of graphs (CPG) as a multichannel modeling approach and explore a set of unique properties of triangular WMNs. In each layer of CPG with a single channel, we design a node coordinate scheme thatmore » retains the symmetric property of triangular meshes and develop a function for the assignment of node identity numbers based on their coordinates. We also derive a necessary-sufficient condition for interference-free links and combinatorial formulas to determine the number of the shortest paths for channel realization in triangular WMNs.« less

Ising antiferromagnet on a finite triangular lattice with free boundary conditions

NASA Astrophysics Data System (ADS)

Kim, Seung-Yeon

2015-11-01

The exact integer values for the density of states of the Ising model on an equilateral triangular lattice with free boundary conditions are evaluated up to L = 24 spins on a side for the first time by using the microcanonical transfer matrix. The total number of states is 2 N s = 2300 ≈ 2.037 × 1090 for L = 24, where N s = L( L+1)/2 is the number of spins. Classifying all 2300 spin states according to their energy values is an enormous work. From the density of states, the exact partition function zeros in the complex temperature plane of the triangular-lattice Ising model are evaluated. Using the density of states and the partition function zeros, we investigate the properties of the triangularlattice Ising antiferromagnet. The scaling behavior of the ground-state entropy and the form of the correlation length at T = 0 are studied for the triangular-lattice Ising antiferromagnet with free boundary conditions. Also, the scaling behavior of the Fisher edge singularity is investigated.

Triangular flow of negative pions emitted in PbAu collisions at √{sNN} = 17.3 GeV

NASA Astrophysics Data System (ADS)

Adamová, D.; Agakichiev, G.; Andronic, A.; Antończyk, D.; Appelshäuser, H.; Belaga, V.; Bielčíková, J.; Braun-Munzinger, P.; Busch, O.; Cherlin, A.; Damjanović, S.; Dietel, T.; Dietrich, L.; Drees, A.; Dubitzky, W.; Esumi, S. I.; Filimonov, K.; Fomenko, K.; Fraenkel, Z.; Garabatos, C.; Glässel, P.; Hering, G.; Holeczek, J.; Kalisky, M.; Karpenko, Iu.; Krobath, G.; Kushpil, V.; Maas, A.; Marín, A.; Milošević, J.; Miśkowiec, D.; Panebrattsev, Y.; Petchenova, O.; Petráček, V.; Radomski, S.; Rak, J.; Ravinovich, I.; Rehak, P.; Sako, H.; Schmitz, W.; Schuchmann, S.; Sedykh, S.; Shimansky, S.; Stachel, J.; Šumbera, M.; Tilsner, H.; Tserruya, I.; Tsiledakis, G.; Wessels, J. P.; Wienold, T.; Wurm, J. P.; Yurevich, S.; Yurevich, V.

2017-01-01

Differential triangular flow, v3 (pT), of negative pions is measured at √{sNN} = 17.3 GeV around midrapidity by the CERES/NA45 experiment at CERN in central PbAu collisions in the range 0-30% with a mean centrality of 5.5%. This is the first measurement as a function of transverse momentum of the triangular flow at SPS energies. The pT range extends from about 0.05 GeV/c to more than 2 GeV/c. The triangular flow magnitude, corrected for the HBT effects, is smaller by a factor of about 2 than the one measured by the PHENIX experiment at RHIC and the ALICE experiment at the LHC. Within the analyzed range of central collisions no significant centrality dependence is observed. The data are found to be well described by a viscous hydrodynamic calculation combined with an UrQMD cascade model for the late stages.

A computerized symbolic integration technique for development of triangular and quadrilateral composite shallow-shell finite elements

NASA Technical Reports Server (NTRS)

Anderson, C. M.; Noor, A. K.

1975-01-01

Computerized symbolic integration was used in conjunction with group-theoretic techniques to obtain analytic expressions for the stiffness, geometric stiffness, consistent mass, and consistent load matrices of composite shallow shell structural elements. The elements are shear flexible and have variable curvature. A stiffness (displacement) formulation was used with the fundamental unknowns consisting of both the displacement and rotation components of the reference surface of the shell. The triangular elements have six and ten nodes; the quadrilateral elements have four and eight nodes and can have internal degrees of freedom associated with displacement modes which vanish along the edges of the element (bubble modes). The stiffness, geometric stiffness, consistent mass, and consistent load coefficients are expressed as linear combinations of integrals (over the element domain) whose integrands are products of shape functions and their derivatives. The evaluation of the elemental matrices is divided into two separate problems - determination of the coefficients in the linear combination and evaluation of the integrals. The integrals are performed symbolically by using the symbolic-and-algebraic-manipulation language MACSYMA. The efficiency of using symbolic integration in the element development is demonstrated by comparing the number of floating-point arithmetic operations required in this approach with those required by a commonly used numerical quadrature technique.

A topological framework for interactive queries on 3D models in the Web.

PubMed

Figueiredo, Mauro; Rodrigues, José I; Silvestre, Ivo; Veiga-Pires, Cristina

2014-01-01

Several technologies exist to create 3D content for the web. With X3D, WebGL, and X3DOM, it is possible to visualize and interact with 3D models in a web browser. Frequently, three-dimensional objects are stored using the X3D file format for the web. However, there is no explicit topological information, which makes it difficult to design fast algorithms for applications that require adjacency and incidence data. This paper presents a new open source toolkit TopTri (Topological model for Triangle meshes) for Web3D servers that builds the topological model for triangular meshes of manifold or nonmanifold models. Web3D client applications using this toolkit make queries to the web server to get adjacent and incidence information of vertices, edges, and faces. This paper shows the application of the topological information to get minimal local points and iso-lines in a 3D mesh in a web browser. As an application, we present also the interactive identification of stalactites in a cave chamber in a 3D web browser. Several tests show that even for large triangular meshes with millions of triangles, the adjacency and incidence information is returned in real time making the presented toolkit appropriate for interactive Web3D applications.

A Topological Framework for Interactive Queries on 3D Models in the Web

PubMed Central

Figueiredo, Mauro; Rodrigues, José I.; Silvestre, Ivo; Veiga-Pires, Cristina

2014-01-01

Several technologies exist to create 3D content for the web. With X3D, WebGL, and X3DOM, it is possible to visualize and interact with 3D models in a web browser. Frequently, three-dimensional objects are stored using the X3D file format for the web. However, there is no explicit topological information, which makes it difficult to design fast algorithms for applications that require adjacency and incidence data. This paper presents a new open source toolkit TopTri (Topological model for Triangle meshes) for Web3D servers that builds the topological model for triangular meshes of manifold or nonmanifold models. Web3D client applications using this toolkit make queries to the web server to get adjacent and incidence information of vertices, edges, and faces. This paper shows the application of the topological information to get minimal local points and iso-lines in a 3D mesh in a web browser. As an application, we present also the interactive identification of stalactites in a cave chamber in a 3D web browser. Several tests show that even for large triangular meshes with millions of triangles, the adjacency and incidence information is returned in real time making the presented toolkit appropriate for interactive Web3D applications. PMID:24977236

A multigrid method for steady Euler equations on unstructured adaptive grids

NASA Technical Reports Server (NTRS)

Riemslagh, Kris; Dick, Erik

1993-01-01

A flux-difference splitting type algorithm is formulated for the steady Euler equations on unstructured grids. The polynomial flux-difference splitting technique is used. A vertex-centered finite volume method is employed on a triangular mesh. The multigrid method is in defect-correction form. A relaxation procedure with a first order accurate inner iteration and a second-order correction performed only on the finest grid, is used. A multi-stage Jacobi relaxation method is employed as a smoother. Since the grid is unstructured a Jacobi type is chosen. The multi-staging is necessary to provide sufficient smoothing properties. The domain is discretized using a Delaunay triangular mesh generator. Three grids with more or less uniform distribution of nodes but with different resolution are generated by successive refinement of the coarsest grid. Nodes of coarser grids appear in the finer grids. The multigrid method is started on these grids. As soon as the residual drops below a threshold value, an adaptive refinement is started. The solution on the adaptively refined grid is accelerated by a multigrid procedure. The coarser multigrid grids are generated by successive coarsening through point removement. The adaption cycle is repeated a few times. Results are given for the transonic flow over a NACA-0012 airfoil.

6-DoF Haptic Rendering Using Continuous Collision Detection between Points and Signed Distance Fields.

PubMed

Hongyi Xu; Barbic, Jernej

2017-01-01

We present an algorithm for fast continuous collision detection between points and signed distance fields, and demonstrate how to robustly use it for 6-DoF haptic rendering of contact between objects with complex geometry. Continuous collision detection is often needed in computer animation, haptics, and virtual reality applications, but has so far only been investigated for polygon (triangular) geometry representations. We demonstrate how to robustly and continuously detect intersections between points and level sets of the signed distance field. We suggest using an octree subdivision of the distance field for fast traversal of distance field cells. We also give a method to resolve continuous collisions between point clouds organized into a tree hierarchy and a signed distance field, enabling rendering of contact between rigid objects with complex geometry. We investigate and compare two 6-DoF haptic rendering methods now applicable to point-versus-distance field contact for the first time: continuous integration of penalty forces, and a constraint-based method. An experimental comparison to discrete collision detection demonstrates that the continuous method is more robust and can correctly resolve collisions even under high velocities and during complex contact.

Effects of Shannon entropy and electric field on polaron in RbCl triangular quantum dot

NASA Astrophysics Data System (ADS)

M, Tiotsop; A, J. Fotue; S, C. Kenfack; N, Issofa; H, Fotsin; L, C. Fai

2016-04-01

In this paper, the time evolution of the quantum mechanical state of a polaron is examined using the Pekar type variational method on the condition of the electric-LO-phonon strong-coupling and polar angle in RbCl triangular quantum dot. We obtain the eigenenergies, and the eigenfunctions of the ground state, and the first excited state respectively. This system in a quantum dot can be treated as a two-level quantum system qubit and the numerical calculations are performed. The effects of Shannon entropy and electric field on the polaron in the RbCl triangular quantum dot are also studied.

Direct Measurement of the Topological Charge in Elliptical Beams Using Diffraction by a Triangular Aperture.

PubMed

Melo, Leandro A; Jesus-Silva, Alcenísio J; Chávez-Cerda, Sabino; Ribeiro, Paulo H Souto; Soares, Willamys C

2018-04-23

We introduce a simple method to characterize the topological charge associated with the orbital angular momentum of a m-order elliptic light beam. This method consists in the observation of the far field pattern of the beam carrying orbital angular momentum, diffracted from a triangular aperture. We show numerically and experimentally, for Mathieu, Ince-Gaussian, and vortex Hermite-Gaussian beams, that only isosceles triangular apertures allow us to determine in a precise and direct way, the magnitude m of the order and the number and sign of unitary topological charges of isolated vortices inside the core of these beams.

Nonlinear vibrations of thin arbitrarily laminated composite plates subjected to harmonic excitations using DKT elements

NASA Astrophysics Data System (ADS)

Chiang, C. K.; Xue, David Y.; Mei, Chuh

1993-04-01

A finite element formulation is presented for determining the large-amplitude free and steady-state forced vibration response of arbitrarily laminated anisotropic composite thin plates using the Discrete Kirchhoff Theory (DKT) triangular elements. The nonlinear stiffness and harmonic force matrices of an arbitrarily laminated composite triangular plate element are developed for nonlinear free and forced vibration analyses. The linearized updated-mode method with nonlinear time function approximation is employed for the solution of the system nonlinear eigenvalue equations. The amplitude-frequency relations for convergence with gridwork refinement, triangular plates, different boundary conditions, lamination angles, number of plies, and uniform versus concentrated loads are presented.

Nonlinear vibrations of thin arbitrarily laminated composite plates subjected to harmonic excitations using DKT elements

NASA Technical Reports Server (NTRS)

Chiang, C. K.; Xue, David Y.; Mei, Chuh

1993-01-01

A finite element formulation is presented for determining the large-amplitude free and steady-state forced vibration response of arbitrarily laminated anisotropic composite thin plates using the Discrete Kirchhoff Theory (DKT) triangular elements. The nonlinear stiffness and harmonic force matrices of an arbitrarily laminated composite triangular plate element are developed for nonlinear free and forced vibration analyses. The linearized updated-mode method with nonlinear time function approximation is employed for the solution of the system nonlinear eigenvalue equations. The amplitude-frequency relations for convergence with gridwork refinement, triangular plates, different boundary conditions, lamination angles, number of plies, and uniform versus concentrated loads are presented.

Magnetoelectric control of spin-chiral ferroelectric domains in a triangular lattice antiferromagnet

NASA Astrophysics Data System (ADS)

Kimura, Kenta; Nakamura, Hiroyuki; Ohgushi, Kenya; Kimura, Tsuyoshi

2008-10-01

We have grown single crystals of a triangular lattice antiferromagnet (TLA), CuCrO2 , and investigated the correlation between magnetic and dielectric properties. Two magnetic phase transitions are observed at TN2≈24.2K and TN1≈23.6K . It was found that ferroelectric polarization along the triangular lattice plane develops at TN1 , suggesting that the system undergoes a transition into an out-of-plane 120° spin-chiral phase at TN1 . The TLA provides an opportunity for unique magnetoelectric control of spin-chiral ferroelectric domain structures by means of electric and/or magnetic fields.

Yu-Shiba-Rusinov states of impurities in a triangular lattice of NbSe2 with spin-orbit coupling

NASA Astrophysics Data System (ADS)

Ptok, Andrzej; Głodzik, Szczepan; Domański, Tadeusz

2017-11-01

We study the topography of the spin-polarized bound states of magnetic impurities embedded in a triangular lattice of a superconducting host. Such states have been observed experimentally in 2 H -NbSe2 crystal [G. C. Ménard et al., Nat. Phys. 11, 1013 (2015), 10.1038/nphys3508], and they revealed oscillating particle-hole asymmetry extending to tens of nanometers. Using the Bogoliubov-de Gennes approach, we explore the Yu-Shiba-Rusinov states in the presence of spin-orbit interaction. We also study the bound states of double impurities for several relative positions in a triangular lattice.

Electronic spectrum of trilayer graphene

NASA Astrophysics Data System (ADS)

Kumar, S.; Ajay

2014-08-01

Present work deals with the analysis of the single particle electronic spectral function in trilayer (ABC-, ABA- and AAA-stacked) graphene. Tight binding Hamiltonian containing intralayer nearest-neighbor and next-nearest neighbor hopping along-with the interlayer coupling parameter within two triangular sub-lattice approach for trilayer graphene has been employed. The expression of single particle spectral functions A(kw) is obtained within mean-field Green's function equations of motion approach. Spectral function at Γ, M and K points of the Brillouin zone has been numerically computed. It is pointed out that the nature of electronic states at different points of Brillouin zone is found to be influenced by stacking order and Coulomb interactions. At Γ and M points, a trilayer splitting is predicted while at K point a bilayer splitting effect is observed due to crossing of two bands (at K point). Interlayer coupling ( t_{ bot } ) is found to be responsible for the splitting of quasi-particle peaks at each point of Brillouin zone. The influence of t_{ bot } in trilayer graphene is prominent for AAA-stacking compared to ABC- and ABA-stacking. On the other hand, onsite Coulomb interaction reduces the trilayer splitting effect into bilayer splitting at Γ and M points of Brillouin zone and bilayer splitting into single peak spectral function at K point with a shifting of the peak away from Fermi level.

Analysis of complex elastic structures by a Rayleigh-Ritz component modes method using Lagrange multipliers. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Klein, L. R.

1974-01-01

The free vibrations of elastic structures of arbitrary complexity were analyzed in terms of their component modes. The method was based upon the use of the normal unconstrained modes of the components in a Rayleigh-Ritz analysis. The continuity conditions were enforced by means of Lagrange Multipliers. Examples of the structures considered are: (1) beams with nonuniform properties; (2) airplane structures with high or low aspect ratio lifting surface components; (3) the oblique wing airplane; and (4) plate structures. The method was also applied to the analysis of modal damping of linear elastic structures. Convergence of the method versus the number of modes per component and/or the number of components is discussed and compared to more conventional approaches, ad-hoc methods, and experimental results.

Adapting the Euler-Lagrange equation to study one-dimensional motions under the action of a constant force

NASA Astrophysics Data System (ADS)

Dias, Clenilda F.; Araújo, Maria A. S.; Carvalho-Santos, Vagson L.

2018-01-01

The Euler-Lagrange equations (ELE) are very important in the theoretical description of several physical systems. In this work we have used a simplified form of ELE to study one-dimensional motions under the action of a constant force. From the use of the definition of partial derivative, we have proposed two operators, here called mean delta operators, which may be used to solve the ELE in a simplest way. We have applied this simplification to solve three simple mechanical problems in which the particle is under the action of the gravitational field: a free fall body, the Atwood’s machine and the inclined plan. The proposed simplification can be used to introduce the lagrangian formalism in teaching classical mechanics in introductory physics courses.

A domain decomposition approach to implementing fault slip in finite-element models of quasi-static and dynamic crustal deformation

USGS Publications Warehouse

Aagaard, Brad T.; Knepley, M.G.; Williams, C.A.

2013-01-01

We employ a domain decomposition approach with Lagrange multipliers to implement fault slip in a finite-element code, PyLith, for use in both quasi-static and dynamic crustal deformation applications. This integrated approach to solving both quasi-static and dynamic simulations leverages common finite-element data structures and implementations of various boundary conditions, discretization schemes, and bulk and fault rheologies. We have developed a custom preconditioner for the Lagrange multiplier portion of the system of equations that provides excellent scalability with problem size compared to conventional additive Schwarz methods. We demonstrate application of this approach using benchmarks for both quasi-static viscoelastic deformation and dynamic spontaneous rupture propagation that verify the numerical implementation in PyLith.

Cooperatively surrounding control for multiple Euler-Lagrange systems subjected to uncertain dynamics and input constraints

NASA Astrophysics Data System (ADS)

Chen, Liang-Ming; Lv, Yue-Yong; Li, Chuan-Jiang; Ma, Guang-Fu

2016-12-01

In this paper, we investigate cooperatively surrounding control (CSC) of multi-agent systems modeled by Euler-Lagrange (EL) equations under a directed graph. With the consideration of the uncertain dynamics in an EL system, a backstepping CSC algorithm combined with neural-networks is proposed first such that the agents can move cooperatively to surround the stationary target. Then, a command filtered backstepping CSC algorithm is further proposed to deal with the constraints on control input and the absence of neighbors’ velocity information. Numerical examples of eight satellites surrounding one space target illustrate the effectiveness of the theoretical results. Project supported by the National Basic Research Program of China (Grant No. 2012CB720000) and the National Natural Science Foundation of China (Grant Nos. 61304005 and 61403103).

Evaluation of a transient, simultaneous, arbitrary Lagrange-Euler based multi-physics method for simulating the mitral heart valve.

PubMed

Espino, Daniel M; Shepherd, Duncan E T; Hukins, David W L

2014-01-01

A transient multi-physics model of the mitral heart valve has been developed, which allows simultaneous calculation of fluid flow and structural deformation. A recently developed contact method has been applied to enable simulation of systole (the stage when blood pressure is elevated within the heart to pump blood to the body). The geometry was simplified to represent the mitral valve within the heart walls in two dimensions. Only the mitral valve undergoes deformation. A moving arbitrary Lagrange-Euler mesh is used to allow true fluid-structure interaction (FSI). The FSI model requires blood flow to induce valve closure by inducing strains in the region of 10-20%. Model predictions were found to be consistent with existing literature and will undergo further development.

Modelling of Dynamics of a Wheeled Mobile Robot with Mecanum Wheels with the use of Lagrange Equations of the Second Kind

NASA Astrophysics Data System (ADS)

Hendzel, Z.; Rykała, Ł.

2017-02-01

The work presents the dynamic equations of motion of a wheeled mobile robot with mecanum wheels derived with the use of Lagrange equations of the second kind. Mecanum wheels are a new type of wheels used in wheeled mobile robots and they consist of freely rotating rollers attached to the circumference of the wheels. In order to derive dynamic equations of motion of a wheeled mobile robot, the kinetic energy of the system is determined, as well as the generalised forces affecting the system. The resulting mathematical model of a wheeled mobile robot was generated with the use of Maple V software. The results of a solution of inverse and forward problems of dynamics of the discussed object are also published.

Robust adaptive uniform exact tracking control for uncertain Euler-Lagrange system

NASA Astrophysics Data System (ADS)

Yang, Yana; Hua, Changchun; Li, Junpeng; Guan, Xinping

2017-12-01

This paper offers a solution to the robust adaptive uniform exact tracking control for uncertain nonlinear Euler-Lagrange (EL) system. An adaptive finite-time tracking control algorithm is designed by proposing a novel nonsingular integral terminal sliding-mode surface. Moreover, a new adaptive parameter tuning law is also developed by making good use of the system tracking errors and the adaptive parameter estimation errors. Thus, both the trajectory tracking and the parameter estimation can be achieved in a guaranteed time adjusted arbitrarily based on practical demands, simultaneously. Additionally, the control result for the EL system proposed in this paper can be extended to high-order nonlinear systems easily. Finally, a test-bed 2-DOF robot arm is set-up to demonstrate the performance of the new control algorithm.

On a Lagrange-Hamilton formalism describing position and momentum uncertainties

NASA Technical Reports Server (NTRS)

Schuch, Dieter

1993-01-01

According to Heisenberg's uncertainty relation, in quantum mechanics it is not possible to determine, simultaneously, exact values for the position and the momentum of a material system. Calculating the mean value of the Hamiltonian operator with the aid of exact analytic Gaussian wave packet solutions, these uncertainties cause an energy contribution additional to the classical energy of the system. For the harmonic oscillator, e.g., this nonclassical energy represents the ground state energy. It will be shown that this additional energy contribution can be considered as a Hamiltonian function, if it is written in appropriate variables. With the help of the usual Lagrange-Hamilton formalism known from classical particle mechanics, but now considering this new Hamiltonian function, it is possible to obtain the equations of motion for position and momentum uncertainties.

Tool calibration system for micromachining system

DOEpatents

Miller, Donald M.

1979-03-06

A tool calibration system including a tool calibration fixture and a tool height and offset calibration insert for calibrating the position of a tool bit in a micromachining tool system. The tool calibration fixture comprises a yokelike structure having a triangular head, a cavity in the triangular head, and a port which communicates a side of the triangular head with the cavity. Yoke arms integral with the triangular head extend along each side of a tool bar and a tool head of the micromachining tool system. The yoke arms are secured to the tool bar to place the cavity around a tool bit which may be mounted to the end of the tool head. Three linear variable differential transformer's (LVDT) are adjustably mounted in the triangular head along an X axis, a Y axis, and a Z axis. The calibration insert comprises a main base which can be mounted in the tool head of the micromachining tool system in place of a tool holder and a reference projection extending from a front surface of the main base. Reference surfaces of the calibration insert and a reference surface on a tool bar standard length are used to set the three LVDT's of the calibration fixture to the tool reference position. These positions are transferred permanently to a mastering station. The tool calibration fixture is then used to transfer the tool reference position of the mastering station to the tool bit.

Effective elastic moduli of triangular lattice material with defects

NASA Astrophysics Data System (ADS)

Liu, Xiaoyu; Liang, Naigang

2012-10-01

This paper presents an attempt to extend homogenization analysis for the effective elastic moduli of triangular lattice materials with microstructural defects. The proposed homogenization method adopts a process based on homogeneous strain boundary conditions, the micro-scale constitutive law and the micro-to-macro static operator to establish the relationship between the macroscopic properties of a given lattice material to its micro-discrete behaviors and structures. Further, the idea behind Eshelby's equivalent eigenstrain principle is introduced to replace a defect distribution by an imagining displacement field (eigendisplacement) with the equivalent mechanical effect, and the triangular lattice Green's function technique is developed to solve the eigendisplacement field. The proposed method therefore allows handling of different types of microstructural defects as well as its arbitrary spatial distribution within a general and compact framework. Analytical closed-form estimations are derived, in the case of the dilute limit, for all the effective elastic moduli of stretch-dominated triangular lattices containing fractured cell walls and missing cells, respectively. Comparison with numerical results, the Hashin-Shtrikman upper bounds and uniform strain upper bounds are also presented to illustrate the predictive capability of the proposed method for lattice materials. Based on this work, we propose that not only the effective Young's and shear moduli but also the effective Poisson's ratio of triangular lattice materials depend on the number density of fractured cell walls and their spatial arrangements.

Fortifying the Bone-Implant Interface Part 2: An In Vivo Evaluation of 3D-Printed and TPS-Coated Triangular Implants.

PubMed

MacBarb, Regina F; Lindsey, Derek P; Woods, Shane A; Lalor, Peggy A; Gundanna, Mukund I; Yerby, Scott A

2017-01-01

Minimally invasive surgical fusion of the sacroiliac (SI) joint using machined solid triangular titanium plasma spray (TPS) coated implants has demonstrated positive clinical outcomes in SI joint pain patients. Additive manufactured (AM), i.e. 3D-printed, fenestrated triangular titanium implants with porous surfaces and bioactive agents, such as nanocrystalline hydroxyapatite (HA) or autograft, may further optimize bony fixation and subsequent biomechanical stability. A bilateral ovine distal femoral defect model was used to evaluate the cancellous bone-implant interfaces of TPS-coated and AM implants. Four implant groups (n=6/group/time-point) were included: 1)TPS-coated, 2)AM, 3)AM+HA, and 4)AM+Autograft. The bone-implant interfaces of 6- and 12-week specimens were investigated via radiographic, biomechanical, and histomorphometric methods. Imaging showed peri-implant bone formation around all implants. Push-out testing demonstrated forces greater than 2500 N, with no significant differences among groups. While TPS implants failed primarily at the bone-implant interface, AM groups failed within bone ~2-3mm away from implant surfaces. All implants exhibited bone ongrowth, with no significant differences among groups. AM implants had significantly more bone ingrowth into their porous surfaces than TPS-coated implants ( p <0.0001). Of the three AM groups, AM+Auto implants had the greatest bone ingrowth into the porous surface and through their core ( p <0.002). Both TPS and AM implants exhibited substantial bone ongrowth and ingrowth, with additional bone through growth into the AM implants' core. Overall, AM implants experienced significantly more bone infiltration compared to TPS implants. While HA-coating did not further enhance results, the addition of autograft fostered greater osteointegration for AM implants. Additive manufactured implants with a porous surface provide a highly interconnected porous surface that has comparatively greater surface area for bony integration. Results suggest this may prove advantageous toward promoting enhanced biomechanical stability compared to TPS-coated implants for SI joint fusion procedures.

Differential effects of labyrinthine dysfunction on distance and direction during blindfolded walking of a triangular path.

PubMed

Glasauer, S; Amorim, M-A; Viaud-Delmon, I; Berthoz, A

2002-08-01

While we walk through the environment, we constantly receive inputs from different sensory systems. For us to accomplish a given task, for example to reach a target location, the sensory information has to be integrated to update our knowledge of self-position and self-orientation with respect to the target so that we can correctly plan and perform the remaining trajectory. As has been shown previously, vestibular information plays a minor role in the performance of linear goal-directed locomotion when walking blindfolded toward a previously seen target within a few meters. The present study extends the question of whether vestibular information is a requirement for goal-directed locomotion by studying a more complex task that also involves rotation: walking a triangular path. Furthermore, studying this task provides information about how we walk a given trajectory, how we move around corners, and whether we are able to return to the starting point. Seven young male, five labyrinthine-defective (LD) and five age- and gender-matched control subjects were asked to walk a previously seen triangular path, which was marked on the ground, first without vision (EC) and then with vision (EO). Each subject performed three clockwise (CW) and three counterclockwise (CCW) walks under the EC condition and one CW and CCW walk under the EO condition. The movement of the subjects was recorded by means of a 3D motion analysis system. Analysis of the data showed that LD subjects had, in the EC condition, a significantly larger final arrival error, which was due to increased directional errors during the turns. However, there was no difference between the groups as regards the overall path length walked. This shows that LD subjects were able to plan and execute the given trajectory without vision, but failed to turn correctly around the corners. Hence, the results demonstrate that vestibular information enhances the ability to perform a planned trajectory incorporating whole body rotations when no visual feedback is available.

Recent Development in the CESE Method for the Solution of the Navier-Stokes Equations Using Unstructured Triangular or Tetrahedral Meshes With High Aspect Ratio

NASA Technical Reports Server (NTRS)

Chang, Sin-Chung; Chang, Chau-Lyan; Yen, Joseph C.

2013-01-01

In the multidimensional CESE development, triangles and tetrahedra turn out to be the most natural building blocks for 2D and 3D spatial meshes. As such the CESE method is compatible with the simplest unstructured meshes and thus can be easily applied to solve problems with complex geometries. However, because the method uses space-time staggered stencils, solution decoupling may become a real nuisance in applications involving unstructured meshes. In this paper we will describe a simple and general remedy which, according to numerical experiments, has removed any possibility of solution decoupling. Moreover, in a real-world viscous flow simulation near a solid wall, one often encounters a case where a boundary with high curvature or sharp corner is surrounded by triangular/tetrahedral meshes of extremely high aspect ratio (up to 106). For such an extreme case, the spatial projection of a space-time compounded conservation element constructed using the original CESE design may become highly concave and thus its centroid (referred to as a spatial solution point) may lie far outside of the spatial projection. It could even be embedded beyond a solid wall boundary and causes serious numerical difficulties. In this paper we will also present a new procedure for constructing conservation elements and solution elements which effectively overcomes the difficulties associated with the original design. Another difficulty issue which was addressed more recently is the wellknown fact that accuracy of gradient computations involving triangular/tetrahedral grids deteriorates rapidly as the aspect ratio of grid cells increases. The root cause of this difficulty was clearly identified and several remedies to overcome it were found through a rigorous mathematical analysis. However, because of the length of the current paper and the complexity of mathematics involved, this new work will be presented in another paper.

Extrahepatic Diseases and NAFLD: The Triangular Relationship between NAFLD, Type 2-Diabetes and Dysbiosis.

PubMed

Scorletti, Eleonora; Byrne, Christopher D

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of liver diseases from simple steatosis with hepatic lipid accumulation to end-stage liver disease with decompensated cirrhosis, liver failure and hepatocellular carcinoma. Recent data from the USA showed that in 2013, NAFLD was the second most frequent indication for liver transplantation behind hepatitis C. Since there are now effective treatments for hepatitis C and there is currently no licensed treatment for NAFLD, it has been predicted that over the next 10-15 years, NAFLD will replace hepatitis C as the most frequent indication for liver transplantation. Besides, increasing the risk of hepatocellular carcinoma and end-stage liver disease, it has recently become clear that NAFLD also increases risk of extrahepatic diseases such as type 2 diabetes mellitus (T2DM), cardiovascular disease, cardiac diseases and chronic kidney disease, to name but a few. Of each of these extrahepatic diseases, the evidence to date suggests that NAFLD is a strong risk factor for T2DM. When NAFLD occurs in combination with obesity and insulin resistance (as it frequently does), there is a marked increase in risk of incident T2DM with possible synergism occurring between liver fat accumulation, insulin resistance and obesity to further increase risk of development of T2DM. Thus, there is a reciprocal relationship between NAFLD as a risk factor for T2DM, and T2DM as a risk factor for liver disease progression in NAFLD. Moreover, recent evidence now points to the importance of perturbation of the intestinal microbiota (dysbiosis) in both T2DM and NAFLD. Consequently, there is a triangular relationship between dysbiosis and T2DM and NAFLD. This review will focus on T2DM as a key extrahepatic complication of NAFLD and will describe and discuss the triangular relationship between dysbiosis and T2DM and NAFLD and the factors and potential mechanisms underpinning this relationship. © 2016 S. Karger AG, Basel.

Anisotropic adhesion properties of triangular-tip-shaped micropillars.

PubMed

Kwak, Moon Kyu; Jeong, Hoon Eui; Bae, Won Gyu; Jung, Ho-Sup; Suh, Kahp Y

2011-08-22

Directional dry adhesive microstructures consisting of high-density triangular-tip-shaped micropillars are described. The wide-tip structures allow for unique directional shear adhesion properties with respect to the peeling direction, along with relatively high normal adhesion. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Triangular Plots and Spreadsheet Software.

ERIC Educational Resources Information Center

Holm, Paul Eric

1988-01-01

Describes how the limitations of the built-in graphics capabilities of spreadsheet software can be overcome by making full use of the flexibility of the grahics options. Uses triangular plots with labeled field boundaries produced using Lotus 1-2-3 to demonstrate these techniques and their use in teaching geology. (CW)

All Square Chiliagonal Numbers

ERIC Educational Resources Information Center

A?iru, Muniru A.

2016-01-01

A square chiliagonal number is a number which is simultaneously a chiliagonal number and a perfect square (just as the well-known square triangular number is both triangular and square). In this work, we determine which of the chiliagonal numbers are perfect squares and provide the indices of the corresponding chiliagonal numbers and square…

Worst case estimation of homology design by convex analysis

NASA Technical Reports Server (NTRS)

Yoshikawa, N.; Elishakoff, Isaac; Nakagiri, S.

1998-01-01

The methodology of homology design is investigated for optimum design of advanced structures. for which the achievement of delicate tasks by the aid of active control system is demanded. The proposed formulation of homology design, based on the finite element sensitivity analysis, necessarily requires the specification of external loadings. The formulation to evaluate the worst case for homology design caused by uncertain fluctuation of loadings is presented by means of the convex model of uncertainty, in which uncertainty variables are assigned to discretized nodal forces and are confined within a conceivable convex hull given as a hyperellipse. The worst case of the distortion from objective homologous deformation is estimated by the Lagrange multiplier method searching the point to maximize the error index on the boundary of the convex hull. The validity of the proposed method is demonstrated in a numerical example using the eleven-bar truss structure.

Concept Design of Cryogenic Propellant Storage and Transfer for Space Exploration

NASA Technical Reports Server (NTRS)

Free, James M.; Motil, Susan M.; Kortes, Trudy F.; Meyer, Michael L.; taylor, William J.

2012-01-01

NASA is in the planning and investigation process of developing innovative paths for human space exploration that strengthen the capability to extend human and robotic presence beyond low Earth orbit and throughout the solar system. NASA is establishing the foundations to enable humans to safely reach multiple potential destinations, including the Moon, asteroids, Lagrange points, and Mars and its environs through technology and capability development. To achieve access to these destinations within a reasonable flight time will require the use of high performance cryogenic propulsion systems. Therefore NASA is examining mission concepts for a Cryogenic Propellant Storage and Transfer (CPST) Flight Demonstration which will test and validate key capabilities and technologies required for future exploration elements such as large cryogenic propulsion stages and propellant depots. The CPST project will perform key ground testing in fiscal year 2012 and execute project formulation and implementation leading to a flight demonstration in 2017.

Application of GA, PSO, and ACO algorithms to path planning of autonomous underwater vehicles

NASA Astrophysics Data System (ADS)

Aghababa, Mohammad Pourmahmood; Amrollahi, Mohammad Hossein; Borjkhani, Mehdi

2012-09-01

In this paper, an underwater vehicle was modeled with six dimensional nonlinear equations of motion, controlled by DC motors in all degrees of freedom. Near-optimal trajectories in an energetic environment for underwater vehicles were computed using a numerical solution of a nonlinear optimal control problem (NOCP). An energy performance index as a cost function, which should be minimized, was defined. The resulting problem was a two-point boundary value problem (TPBVP). A genetic algorithm (GA), particle swarm optimization (PSO), and ant colony optimization (ACO) algorithms were applied to solve the resulting TPBVP. Applying an Euler-Lagrange equation to the NOCP, a conjugate gradient penalty method was also adopted to solve the TPBVP. The problem of energetic environments, involving some energy sources, was discussed. Some near-optimal paths were found using a GA, PSO, and ACO algorithms. Finally, the problem of collision avoidance in an energetic environment was also taken into account.