Impact ionization in GaAs: A screened exchange density-functional approach
International Nuclear Information System (INIS)
Picozzi, S.; Asahi, R.; Geller, C.B.; Continenza, A.; Freeman, A.J.
2001-01-01
Results are presented of a fully ab initio calculation of impact ionization rates in GaAs within the density functional theory framework, using a screened-exchange formalism and the highly precise all-electron full-potential linearized augmented plane wave method. The calculated impact ionization rates show a marked orientation dependence in k space, indicating the strong restrictions imposed by the conservation of energy and momentum. This anisotropy diminishes as the impacting electron energy increases. A Keldysh type fit performed on the energy-dependent rate shows a rather soft edge and a threshold energy greater than the direct band gap. The consistency with available Monte Carlo and empirical pseudopotential calculations shows the reliability of our approach and paves the way to ab initio calculations of pair production rates in new and more complex materials
Beyond the G W approximation: A second-order screened exchange correction
Ren, Xinguo; Marom, Noa; Caruso, Fabio; Scheffler, Matthias; Rinke, Patrick
2015-08-01
Motivated by the recently developed renormalized second-order perturbation theory for ground-state energy calculations, we propose a second-order screened exchange correction (SOSEX) to the G W self-energy. This correction follows the spirit of the SOSEX correction to the random-phase approximation for the electron correlation energy and can be clearly represented in terms of Feynman diagrams. We benchmark the performance of the perturbative G0W0 +SOSEX scheme for a set of molecular systems, including the G2 test set from quantum chemistry as well as benzene and tetracyanoethylene. We find that G0W0 +SOSEX improves over G0W0 for the energy levels of the highest occupied and lowest unoccupied molecular orbitals. In addition, it can resolve some of the difficulties encountered by the G W method for relative energy positions as exemplified by benzene where the energy spacing between certain valence orbitals is severely underestimated.
Extended screened exchange functional derived from transcorrelated density functional theory.
Umezawa, Naoto
2017-09-14
We propose a new formulation of the correlation energy functional derived from the transcorrelated method in use in density functional theory (TC-DFT). An effective Hamiltonian, H TC , is introduced by a similarity transformation of a many-body Hamiltonian, H, with respect to a complex function F: H TC =1FHF. It is proved that an expectation value of H TC for a normalized single Slater determinant, D n , corresponds to the total energy: E[n] = ⟨Ψ n |H|Ψ n ⟩/⟨Ψ n |Ψ n ⟩ = ⟨D n |H TC |D n ⟩ under the two assumptions: (1) The electron density nr associated with a trial wave function Ψ n = D n F is v-representable and (2) Ψ n and D n give rise to the same electron density nr. This formulation, therefore, provides an alternative expression of the total energy that is useful for the development of novel correlation energy functionals. By substituting a specific function for F, we successfully derived a model correlation energy functional, which resembles the functional form of the screened exchange method. The proposed functional, named the extended screened exchange (ESX) functional, is described within two-body integrals and is parametrized for a numerically exact correlation energy of the homogeneous electron gas. The ESX functional does not contain any ingredients of (semi-)local functionals and thus is totally free from self-interactions. The computational cost for solving the self-consistent-field equation is comparable to that of the Hartree-Fock method. We apply the ESX functional to electronic structure calculations for a solid silicon, H - ion, and small atoms. The results demonstrate that the TC-DFT formulation is promising for the systematic improvement of the correlation energy functional.
Regularization methods in Banach spaces
Schuster, Thomas; Hofmann, Bernd; Kazimierski, Kamil S
2012-01-01
Regularization methods aimed at finding stable approximate solutions are a necessary tool to tackle inverse and ill-posed problems. Usually the mathematical model of an inverse problem consists of an operator equation of the first kind and often the associated forward operator acts between Hilbert spaces. However, for numerous problems the reasons for using a Hilbert space setting seem to be based rather on conventions than on an approprimate and realistic model choice, so often a Banach space setting would be closer to reality. Furthermore, sparsity constraints using general Lp-norms or the B
Short-range second order screened exchange correction to RPA correlation energies
Beuerle, Matthias; Ochsenfeld, Christian
2017-11-01
Direct random phase approximation (RPA) correlation energies have become increasingly popular as a post-Kohn-Sham correction, due to significant improvements over DFT calculations for properties such as long-range dispersion effects, which are problematic in conventional density functional theory. On the other hand, RPA still has various weaknesses, such as unsatisfactory results for non-isogyric processes. This can in parts be attributed to the self-correlation present in RPA correlation energies, leading to significant self-interaction errors. Therefore a variety of schemes have been devised to include exchange in the calculation of RPA correlation energies in order to correct this shortcoming. One of the most popular RPA plus exchange schemes is the second order screened exchange (SOSEX) correction. RPA + SOSEX delivers more accurate absolute correlation energies and also improves upon RPA for non-isogyric processes. On the other hand, RPA + SOSEX barrier heights are worse than those obtained from plain RPA calculations. To combine the benefits of RPA correlation energies and the SOSEX correction, we introduce a short-range RPA + SOSEX correction. Proof of concept calculations and benchmarks showing the advantages of our method are presented.
Short-range second order screened exchange correction to RPA correlation energies.
Beuerle, Matthias; Ochsenfeld, Christian
2017-11-28
Direct random phase approximation (RPA) correlation energies have become increasingly popular as a post-Kohn-Sham correction, due to significant improvements over DFT calculations for properties such as long-range dispersion effects, which are problematic in conventional density functional theory. On the other hand, RPA still has various weaknesses, such as unsatisfactory results for non-isogyric processes. This can in parts be attributed to the self-correlation present in RPA correlation energies, leading to significant self-interaction errors. Therefore a variety of schemes have been devised to include exchange in the calculation of RPA correlation energies in order to correct this shortcoming. One of the most popular RPA plus exchange schemes is the second order screened exchange (SOSEX) correction. RPA + SOSEX delivers more accurate absolute correlation energies and also improves upon RPA for non-isogyric processes. On the other hand, RPA + SOSEX barrier heights are worse than those obtained from plain RPA calculations. To combine the benefits of RPA correlation energies and the SOSEX correction, we introduce a short-range RPA + SOSEX correction. Proof of concept calculations and benchmarks showing the advantages of our method are presented.
State Space Methods for Timed Petri Nets
DEFF Research Database (Denmark)
Christensen, Søren; Jensen, Kurt; Mailund, Thomas
2001-01-01
We present two recently developed state space methods for timed Petri nets. The two methods reconciles state space methods and time concepts based on the introduction of a global clock and associating time stamps to tokens. The first method is based on an equivalence relation on states which makes...
Directory of Open Access Journals (Sweden)
Riccardo Lucchetti
2011-05-01
Full Text Available gretl is a general-purpose econometric package, whose most important characteristic is being free software. This ensures that its source code is freely available under the general public license (GPL and, like most GPL software, that it can be used free of charge. As of version 1.8.1 (released in May 2009, it offers a mechanism for handling linear state space models in a reasonably general and efficient way. This article illustrates its main features with two examples.
State space Newton's method for topology optimization
DEFF Research Database (Denmark)
Evgrafov, Anton
2014-01-01
We introduce a new algorithm for solving certain classes of topology optimization problems, which enjoys fast local convergence normally achieved by the full space methods while working in a smaller reduced space. The computational complexity of Newton’s direction finding subproblem in the algori......We introduce a new algorithm for solving certain classes of topology optimization problems, which enjoys fast local convergence normally achieved by the full space methods while working in a smaller reduced space. The computational complexity of Newton’s direction finding subproblem...
Diagrammatic methods in phase-space regularization
International Nuclear Information System (INIS)
Bern, Z.; Halpern, M.B.; California Univ., Berkeley
1987-11-01
Using the scalar prototype and gauge theory as the simplest possible examples, diagrammatic methods are developed for the recently proposed phase-space form of continuum regularization. A number of one-loop and all-order applications are given, including general diagrammatic discussions of the nogrowth theorem and the uniqueness of the phase-space stochastic calculus. The approach also generates an alternate derivation of the equivalence of the large-β phase-space regularization to the more conventional coordinate-space regularization. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Akiyama, Toru; Nakamura, Kohji; Ito, Tomonori [Department of Physics Engineering, Mie University, 1577 Kurima-Machiya, Tsu 514-8507 (Japan); Freeman, Arthur J. [Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208 (United States)
2014-03-31
The electronic band structures and excited states of III-V semiconductors such as GaP, AlP, AlAs, and AlSb for various polytypes are determined employing the screened-exchange density functional calculations implemented in the full-potential linearized augmented plane-wave methods. We demonstrate that GaP and AlSb in the wurtzite (WZ) structure have direct gap while III-V semiconductors in the zinc blende, 4H, and 6H structures considered in this study exhibit an indirect gap. Furthermore, we find that inclusion of Al atoms less than 17% and 83% in the hexagonal Al{sub x}Ga{sub 1−x}P and Al{sub x}Ga{sub 1−x}As alloys, respectively, leads to a direct transition with a gap energy of ∼2.3 eV. The feasibility of III-V semiconductors with a direct gap in WZ structure offers a possible crystal structure engineering to tune the optical properties of semiconductor materials.
Statistical Software for State Space Methods
Directory of Open Access Journals (Sweden)
Jacques J. F. Commandeur
2011-05-01
Full Text Available In this paper we review the state space approach to time series analysis and establish the notation that is adopted in this special volume of the Journal of Statistical Software. We first provide some background on the history of state space methods for the analysis of time series. This is followed by a concise overview of linear Gaussian state space analysis including the modelling framework and appropriate estimation methods. We discuss the important class of unobserved component models which incorporate a trend, a seasonal, a cycle, and fixed explanatory and intervention variables for the univariate and multivariate analysis of time series. We continue the discussion by presenting methods for the computation of different estimates for the unobserved state vector: filtering, prediction, and smoothing. Estimation approaches for the other parameters in the model are also considered. Next, we discuss how the estimation procedures can be used for constructing confidence intervals, detecting outlier observations and structural breaks, and testing model assumptions of residual independence, homoscedasticity, and normality. We then show how ARIMA and ARIMA components models fit in the state space framework to time series analysis. We also provide a basic introduction for non-Gaussian state space models. Finally, we present an overview of the software tools currently available for the analysis of time series with state space methods as they are discussed in the other contributions to this special volume.
Space Archaeology: Attribute, Object, Task and Method
Wang, Xinyuan; Guo, Huadong; Luo, Lei; Liu, Chuansheng
2017-04-01
Archaeology takes the material remains of human activity as the research object, and uses those fragmentary remains to reconstruct the humanistic and natural environment in different historical periods. Space Archaeology is a new branch of the Archaeology. Its study object is the humanistic-natural complex including the remains of human activities and living environments on the earth surface. The research method, space information technologies applied to this complex, is an innovative process concerning archaeological information acquisition, interpretation and reconstruction, and to achieve the 3-D dynamic reconstruction of cultural heritages by constructing the digital cultural-heritage sphere. Space archaeology's attribute is highly interdisciplinary linking several areas of natural and social and humanities. Its task is to reveal the history, characteristics, and patterns of human activities in the past, as well as to understand the evolutionary processes guiding the relationship between human and their environment. This paper summarizes six important aspects of space archaeology and five crucial recommendations for the establishment and development of this new discipline. The six important aspects are: (1) technologies and methods for non-destructive detection of archaeological sites; (2) space technologies for the protection and monitoring of cultural heritages; (3) digital environmental reconstruction of archaeological sites; (4) spatial data storage and data mining of cultural heritages; (5) virtual archaeology, digital reproduction and public information and presentation system; and (6) the construction of scientific platform of digital cultural-heritage sphere. The five key recommendations for establishing the discipline of Space Archaeology are: (1) encouraging the full integration of the strengths of both archaeology and museology with space technology to promote the development of space technologies' application for cultural heritages; (2) a new
Three-dimensional space charge calculation method
International Nuclear Information System (INIS)
Lysenko, W.P.; Wadlinger, E.A.
1981-01-01
A method is presented for calculating space-charge forces suitable for use in a particle tracing code. Poisson's equation is solved in three dimensions with boundary conditions specified on an arbitrary surface by using a weighted residual method. Using a discrete particle distribution as our source input, examples are shown of off-axis, bunched beams of noncircular crosssection in radio-frequency quadrupole (RFQ) and drift-tube linac geometries
Modern methods in topological vector spaces
Wilansky, Albert
2013-01-01
Designed for a one-year course in topological vector spaces, this text is geared toward advanced undergraduates and beginning graduate students of mathematics. The subjects involve properties employed by researchers in classical analysis, differential and integral equations, distributions, summability, and classical Banach and Frechét spaces. Optional problems with hints and references introduce non-locally convex spaces, Köthe-Toeplitz spaces, Banach algebra, sequentially barrelled spaces, and norming subspaces.Extensive introductory chapters cover metric ideas, Banach space, topological vect
Improvement in Space Food Packaging Methods
National Aeronautics and Space Administration — The Space Food Systems Laboratory's (SFSL) current Bulk Overwrap Bag (BOB) package, while simple and effective, leaves room for improvement. Currently, BOBs are...
Space program management methods and tools
Spagnulo, Marcello; Balduccini, Mauro; Nasini, Federico
2013-01-01
Beginning with the basic elements that differentiate space programs from other management challenges, Space Program Management explains through theory and example of real programs from around the world, the philosophical and technical tools needed to successfully manage large, technically complex space programs both in the government and commercial environment. Chapters address both systems and configuration management, the management of risk, estimation, measurement and control of both funding and the program schedule, and the structure of the aerospace industry worldwide.
Noncommutative Phase Spaces by Coadjoint Orbits Method
Directory of Open Access Journals (Sweden)
Ancille Ngendakumana
2011-12-01
Full Text Available We introduce noncommutative phase spaces by minimal couplings (usual one, dual one and their mixing. We then realize some of them as coadjoint orbits of the anisotropic Newton-Hooke groups in two- and three-dimensional spaces. Through these constructions the positions and the momenta of the phase spaces do not commute due to the presence of a magnetic field and a dual magnetic field.
Agile Development Methods for Space Operations
Trimble, Jay; Webster, Chris
2012-01-01
Main stream industry software development practice has gone from a traditional waterfall process to agile iterative development that allows for fast response to customer inputs and produces higher quality software at lower cost. How can we, the space ops community, adopt state of the art software development practice, achieve greater productivity at lower cost, and maintain safe and effective space flight operations? At NASA Ames, we are developing Mission Control Technologies Software, in collaboration with Johnson Space Center (JSC) and, more recently, the Jet Propulsion Laboratory (JPL).
The Fock space method of vibrational analysis.
Jung, Christof; Taylor, Howard S
2010-06-21
A reformulation of a semiclassical theory that presently seems uniquely capable of interpreting generic complex multiresonant vibrational spectra is presented. Once given the spectroscopic Hamiltonian which reveals the set of possible resonant couplings and its eigenstates, the new and old formulations both yield without any further computation level by level dynamical assignments for the spectra. Computing a simple trajectory in phase space reveals the motions that when quantized yield the assigned levels. The reformulation introduces two new projected representations of the wave functions. The first is in action space and the second in angle space. The projected representations often allow the reduced angle space, where nodal searches are made, to be of lower dimension than formally occurred. In addition the action representation is a similarly lower dimension lattice representation whose discreteness and regularity allow higher reduced dimensions to be studied. The lattice representation is used to produce a significantly more complete and detailed assignment of the thiophosgene spectrum than previously published.
Hilbert space methods in partial differential equations
Showalter, Ralph E
1994-01-01
This graduate-level text opens with an elementary presentation of Hilbert space theory sufficient for understanding the rest of the book. Additional topics include boundary value problems, evolution equations, optimization, and approximation.1979 edition.
Phase space methods for degenerate quantum gases
Dalton, Bryan J; Barnett, Stephen M
2015-01-01
Recent experimental progress has enabled cold atomic gases to be studied at nano-kelvin temperatures, creating new states of matter where quantum degeneracy occurs - Bose-Einstein condensates and degenerate Fermi gases. Such quantum states are of macroscopic dimensions. This book presents the phase space theory approach for treating the physics of degenerate quantum gases, an approach already widely used in quantum optics. However, degenerate quantum gases involve massive bosonic and fermionic atoms, not massless photons. The book begins with a review of Fock states for systems of identical atoms, where large numbers of atoms occupy the various single particle states or modes. First, separate modes are considered, and here the quantum density operator is represented by a phase space distribution function of phase space variables which replace mode annihilation, creation operators, the dynamical equation for the density operator determines a Fokker-Planck equation for the distribution function, and measurable...
Systems and methods for free space optical communication
Harper, Warren W [Benton City, WA; Aker, Pamela M [Richland, WA; Pratt, Richard M [Richland, WA
2011-05-10
Free space optical communication methods and systems, according to various aspects are described. The methods and systems are characterized by transmission of data through free space with a digitized optical signal acquired using wavelength modulation, and by discrimination between bit states in the digitized optical signal using a spectroscopic absorption feature of a chemical substance.
Sleeve Push Technique: A Novel Method of Space Gaining.
Verma, Sanjeev; Bhupali, Nameksh Raj; Gupta, Deepak Kumar; Singh, Sombir; Singh, Satinder Pal
2018-01-01
Space gaining is frequently required in orthodontics. Multiple loops were initially used for space gaining and alignment. The most common used mechanics for space gaining is the use of nickel-titanium open coil springs. The disadvantage of nickel-titanium coil spring is that they cannot be used until the arches are well aligned to receive the stiffer stainless steel wires. Therefore, a new method of gaining space during initial alignment and leveling has been developed and named as sleeve push technique (SPT). The nickel-titanium wires, i.e. 0.012 inches and 0.014 inches along with archwire sleeve (protective tubing) can be used in a modified way to gain space along with alignment. This method helps in gaining space right from day 1 of treatment. The archwire sleeve and nickel-titanium wire in this new SPT act as a mutually synergistic combination and provide the orthodontist with a completely new technique for space opening.
Finite element method for time-space-fractional Schrodinger equation
Directory of Open Access Journals (Sweden)
Xiaogang Zhu
2017-07-01
Full Text Available In this article, we develop a fully discrete finite element method for the nonlinear Schrodinger equation (NLS with time- and space-fractional derivatives. The time-fractional derivative is described in Caputo's sense and the space-fractional derivative in Riesz's sense. Its stability is well derived; the convergent estimate is discussed by an orthogonal operator. We also extend the method to the two-dimensional time-space-fractional NLS and to avoid the iterative solvers at each time step, a linearized scheme is further conducted. Several numerical examples are implemented finally, which confirm the theoretical results as well as illustrate the accuracy of our methods.
A Compositional Sweep-Line State Space Exploration Method
DEFF Research Database (Denmark)
Kristensen, Lars Michael; Mailund, Thomas
2002-01-01
State space exploration is a main approach to verification of finite-state systems. The sweep-line method exploits a certain kind of progress present in many systems to reduce peak memory usage during state space exploration. We present a new sweep-line algorithm for a compositional setting where...
Space-time discontinuous Galerkin finite element methods
van der Vegt, Jacobus J.W.; Deconinck, H.; Ricchiuto, M.
2006-01-01
In these notes an introduction is given to space-time discontinuous Galerkin (DG) finite element methods for hyperbolic and parabolic conservation laws on time dependent domains. the space-time DG discretization is explained in detail, including the definition of the numerical fluxes and
Space-time discontinuous Galerkin method for compressible flow
Klaij, C.M.
2006-01-01
The space-time discontinuous Galerkin method allows the simulation of compressible flow in complex aerodynamical applications requiring moving, deforming and locally refined meshes. This thesis contains the space-time discretization of the physical model, a fully explicit solver for the resulting
Homotopy deform method for reproducing kernel space for ...
Indian Academy of Sciences (India)
2016-09-23
s12043-016-1269-8. Homotopy deform method for reproducing kernel space for nonlinear boundary value problems. MIN-QIANG XU. ∗ and YING-ZHEN LIN. School of Science, Zhuhai Campus, Beijing Institute of Technology, ...
An Asymmetrical Space Vector Method for Single Phase Induction Motor
DEFF Research Database (Denmark)
Cui, Yuanhai; Blaabjerg, Frede; Andersen, Gert Karmisholt
2002-01-01
the motor torque performance is not good enough. This paper addresses a new control method, an asymmetrical space vector method with PWM modulation, also a three-phase inverter is used for the main winding and the auxiliary winding. This method with PWM modulation is implemented to control the motor speed...
Symmetric spaces and the Kashiwara-Vergne method
Rouvière, François
2014-01-01
Gathering and updating results scattered in journal articles over thirty years, this self-contained monograph gives a comprehensive introduction to the subject. Its goal is to: - motivate and explain the method for general Lie groups, reducing the proof of deep results in invariant analysis to the verification of two formal Lie bracket identities related to the Campbell-Hausdorff formula (the "Kashiwara-Vergne conjecture"); - give a detailed proof of the conjecture for quadratic and solvable Lie algebras, which is relatively elementary; - extend the method to symmetric spaces; here an obstruction appears, embodied in a single remarkable object called an "e-function"; - explain the role of this function in invariant analysis on symmetric spaces, its relation to invariant differential operators, mean value operators and spherical functions; - give an explicit e-function for rank one spaces (the hyperbolic spaces); - construct an e-function for general symmetric spaces, in the spirit of Kashiwara and Vergne's or...
METHOD OF IMAGE QUALITY ENHANCEMENT FOR SPACE OBJECTS
Directory of Open Access Journals (Sweden)
D. S. Korshunov
2014-07-01
Full Text Available The paper deals with an approach for image quality improvement of the space objects in the visible range of electromagnetic wave spectrum. The proposed method is based on the joint taking into account of both the motion velocity of the space supervisory apparatus and a space object observed in the near-earth space when the time of photo-detector exposure is chosen. The timing of exposure is carried out by light-signal characteristics, which determines the optimal value of the charge package formed in the charge-coupled device being irradiated. Thus, the parameters of onboard observation equipment can be selected, which provides space images suitable for interpretation. The linear resolving capacity is used as quality indicator for space images, giving a complete picture for the image contrast and geometric properties of the object on the photo. Observation scenario modeling of the space object, done by sputnik-inspector, has shown the possibility of increasing the linear resolution up to10% - 20% or up to 40% - 50% depending on the non-complanarity angle at the movement along orbits. The proposed approach to the increase of photographs quality provides getting sharp and highcontrast images of space objects by the optical-electronic equipment of the space-based remote sensing. The usage of these images makes it possible to detect in time the space technology failures, which are the result of its exploitation in the nearearth space. The proposed method can be also applied at the stage of space systems design for optical-electronic surveillance in computer models used for facilities assessment of the shooting equipment information tract.
Aveiro method in reproducing kernel Hilbert spaces under complete dictionary
Mai, Weixiong; Qian, Tao
2017-12-01
Aveiro Method is a sparse representation method in reproducing kernel Hilbert spaces (RKHS) that gives orthogonal projections in linear combinations of reproducing kernels over uniqueness sets. It, however, suffers from determination of uniqueness sets in the underlying RKHS. In fact, in general spaces, uniqueness sets are not easy to be identified, let alone the convergence speed aspect with Aveiro Method. To avoid those difficulties we propose an anew Aveiro Method based on a dictionary and the matching pursuit idea. What we do, in fact, are more: The new Aveiro method will be in relation to the recently proposed, the so called Pre-Orthogonal Greedy Algorithm (P-OGA) involving completion of a given dictionary. The new method is called Aveiro Method Under Complete Dictionary (AMUCD). The complete dictionary consists of all directional derivatives of the underlying reproducing kernels. We show that, under the boundary vanishing condition, bring available for the classical Hardy and Paley-Wiener spaces, the complete dictionary enables an efficient expansion of any given element in the Hilbert space. The proposed method reveals new and advanced aspects in both the Aveiro Method and the greedy algorithm.
Decision Making Methods in Space Economics and Systems Engineering
Shishko, Robert
2006-01-01
This viewgraph presentation reviews various methods of decision making and the impact that they have on space economics and systems engineering. Some of the methods discussed are: Present Value and Internal Rate of Return (IRR); Cost-Benefit Analysis; Real Options; Cost-Effectiveness Analysis; Cost-Utility Analysis; Multi-Attribute Utility Theory (MAUT); and Analytic Hierarchy Process (AHP).
Method for fabricating a substrate having spaced apart microcapillaries thereon
Jarvis, Eric E.
1995-01-01
Methods for manufacturing a self-supporting substrate having a plurality of spaced-apart needles (spikes or microcapillaries) projecting upwardly from a major surface of the substrate. In a preferred method, metal is deposited onto a porous membrane such that the metal extends into the pores, after which the membrane is dissolved.
Sleeve push technique: A novel method of space gaining
Directory of Open Access Journals (Sweden)
Sanjeev Verma
2018-01-01
Full Text Available Space gaining is frequently required in orthodontics. Multiple loops were initially used for space gaining and alignment. The most common used mechanics for space gaining is the use of nickel–titanium open coil springs. The disadvantage of nickel–titanium coil spring is that they cannot be used until the arches are well aligned to receive the stiffer stainless steel wires. Therefore, a new method of gaining space during initial alignment and leveling has been developed and named as sleeve push technique (SPT. The nickel–titanium wires, i.e. 0.012 inches and 0.014 inches along with archwire sleeve (protective tubing can be used in a modified way to gain space along with alignment. This method helps in gaining space right from day 1 of treatment. The archwire sleeve and nickel–titanium wire in this new SPT act as a mutually synergistic combination and provide the orthodontist with a completely new technique for space opening.
Multigrid methods for space fractional partial differential equations
Jiang, Yingjun; Xu, Xuejun
2015-12-01
We propose some multigrid methods for solving the algebraic systems resulting from finite element approximations of space fractional partial differential equations (SFPDEs). It is shown that our multigrid methods are optimal, which means the convergence rates of the methods are independent of the mesh size and mesh level. Moreover, our theoretical analysis and convergence results do not require regularity assumptions of the model problems. Numerical results are given to support our theoretical findings.
Methods for microbiological and immunological studies of space flight crews
Taylor, G. R. (Editor); Zaloguev, S. N. (Editor)
1978-01-01
Systematic laboratory procedures compiled as an outgrowth of a joint U.S./U.S.S.R. microbiological-immunological experiment performed during the Apollo-Soyuz Test Project space flight are presented. Included are mutually compatible methods for the identification of aerobic and microaerophilic bacteria, yeast and yeastlike microorganisms, and filamentous fungi; methods for the bacteriophage typing of Staphylococcus aureus; and methods for determining the sensitivity of S. aureus to antibiotics. Immunological methods using blood and immunological and biochemical methods using salivary parotid fluid are also described. Formulas for media and laboratory reagents used are listed.
The sweep-line state space exploration method
DEFF Research Database (Denmark)
Jensen, Kurt; Kristensen, Lars M.; Mailund, Thomas
2012-01-01
The sweep-line method exploits intrinsic progress in concurrent systems to alleviate the state explosion problem in explicit state model checking. The concept of progress makes it possible to delete states from the memory during state space exploration and thereby reduce peak memory usage...
Space-time adaptive wavelet methods for parabolic evolution problems
Schwab, C.; Stevenson, R.
2009-01-01
With respect to space-time tensor-product wavelet bases, parabolic initial boundary value problems are equivalently formulated as bi-infinite matrix problems. Adaptive wavelet methods are shown to yield sequences of approximate solutions which converge at the optimal rate. In case the spatial domain
Calibration Methods for a Space Borne Backscatter Lidar
Kunz, G.J.
1996-01-01
Lidar returns from cloud decks and from the Earth's surface are useful for calibrating single scatter lidar signals from space. To this end analytical methods (forward and backward) are presented for inverting lidar waveforms in terms of the path integrated lidar retum and the transmission losses
High-resolution methods for fluorescence retrieval from space
Mazzoni, M.; Falorni, P.; Verhoef, W.
2010-01-01
The retrieval from space of a very weak fluorescence signal was studied in the O2A and O2B oxygen atmospheric absorption bands. The accuracy of the method was tested for the retrieval of the chlorophyll fluorescence and reflectance terms contributing to the sensor signal. The radiance at the top of
VanDersarl, Jules J.; Xu, Alexander M.; Melosh, Nicholas A.; Tayebi, Noureddine
2016-02-23
In accordance with the purpose(s) of the present disclosure, as embodied and broadly described herein, embodiments of the present disclosure, in one aspect, relate to methods of making a structure including nanotubes, a structure including nanotubes, methods of delivering a fluid to a cell, methods of removing a fluid to a cell, methods of accessing intracellular space, and the like.
Space Syntax: a method to measure urban space related to social, economic and cognitive factors
van Nes, Akkelies; Yamu, Claudia; Yamu, Claudia; Poplin, Alenka; Devisch, Oswald; De Roo, Gert
2017-01-01
Configurational analysis represented by the method of space syntax allows the modelling of a city that links intuition and science, and it can be used for designing and planning cities, as well as in research (Hillier 2009). Developed by Bill Hillier and his colleagues at the University College
A New Method of Space Travel Optimized for Space Tourism and Colonization
Turek, Philip A.
2006-01-01
High costs associated with expendable rockets are stifling the development of permanent space colonies. A new method of space travel is presented that enjoys significantly increased performance and reduced cost relative to competing concepts. Based on recycling the kinetic energy of an arriving spacecraft, up to 200 MW of average electrical power is generated and sustained for 2 minutes, and is immediately applied in launching a departing partner spacecraft. The resulting required delta vee for a round trip between low Earth orbit (LEO) and geosynchronous orbit (GEO) drops from 7.6 km/s to 0.54 km/s when 3 recycling stations with an 80 % energy coupling efficiency are used to exchange kinetic energy between 8 partner spacecraft transiting the same route. This method is well suited for round trip high volume space travel such as space tourism traffic to LEO, lunar orbit, and beyond. As the kinetic energy of an arriving spacecraft is the power source for launching departing spacecraft, nascent lunar colonies can electrically launch 26,000 kg payloads long before sustained 100 MW level power supplies become locally available. A pair of recycling stations at an orbiting space colony construction site provides a resource of net impulse, net torque, and electrical power to the colony irrespective of the contents of the arriving payloads. Kinetic energy recycling technology, configuration, operations, and near Earth applications are described.
Estimation methods for nonlinear state-space models in ecology
DEFF Research Database (Denmark)
Pedersen, Martin Wæver; Berg, Casper Willestofte; Thygesen, Uffe Høgsbro
2011-01-01
The use of nonlinear state-space models for analyzing ecological systems is increasing. A wide range of estimation methods for such models are available to ecologists, however it is not always clear, which is the appropriate method to choose. To this end, three approaches to estimation in the theta...... Markov model (HMM). The second method uses the mixed effects modeling and fast numerical integration framework of the AD Model Builder (ADMB) open-source software. The third alternative is to use the popular Bayesian framework of BUGS. The study showed that state and parameter estimation performance...
Grassmann phase space methods for fermions. II. Field theory
Energy Technology Data Exchange (ETDEWEB)
Dalton, B.J., E-mail: bdalton@swin.edu.au [Centre for Quantum and Optical Science, Swinburne University of Technology, Melbourne, Victoria 3122 (Australia); Jeffers, J. [Department of Physics, University of Strathclyde, Glasgow G4ONG (United Kingdom); Barnett, S.M. [School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)
2017-02-15
In both quantum optics and cold atom physics, the behaviour of bosonic photons and atoms is often treated using phase space methods, where mode annihilation and creation operators are represented by c-number phase space variables, with the density operator equivalent to a distribution function of these variables. The anti-commutation rules for fermion annihilation, creation operators suggests the possibility of using anti-commuting Grassmann variables to represent these operators. However, in spite of the seminal work by Cahill and Glauber and a few applications, the use of Grassmann phase space methods in quantum-atom optics to treat fermionic systems is rather rare, though fermion coherent states using Grassmann variables are widely used in particle physics. This paper presents a phase space theory for fermion systems based on distribution functionals, which replace the density operator and involve Grassmann fields representing anti-commuting fermion field annihilation, creation operators. It is an extension of a previous phase space theory paper for fermions (Paper I) based on separate modes, in which the density operator is replaced by a distribution function depending on Grassmann phase space variables which represent the mode annihilation and creation operators. This further development of the theory is important for the situation when large numbers of fermions are involved, resulting in too many modes to treat separately. Here Grassmann fields, distribution functionals, functional Fokker–Planck equations and Ito stochastic field equations are involved. Typical applications to a trapped Fermi gas of interacting spin 1/2 fermionic atoms and to multi-component Fermi gases with non-zero range interactions are presented, showing that the Ito stochastic field equations are local in these cases. For the spin 1/2 case we also show how simple solutions can be obtained both for the untrapped case and for an optical lattice trapping potential.
Grassmann phase space methods for fermions. II. Field theory
International Nuclear Information System (INIS)
Dalton, B.J.; Jeffers, J.; Barnett, S.M.
2017-01-01
In both quantum optics and cold atom physics, the behaviour of bosonic photons and atoms is often treated using phase space methods, where mode annihilation and creation operators are represented by c-number phase space variables, with the density operator equivalent to a distribution function of these variables. The anti-commutation rules for fermion annihilation, creation operators suggests the possibility of using anti-commuting Grassmann variables to represent these operators. However, in spite of the seminal work by Cahill and Glauber and a few applications, the use of Grassmann phase space methods in quantum-atom optics to treat fermionic systems is rather rare, though fermion coherent states using Grassmann variables are widely used in particle physics. This paper presents a phase space theory for fermion systems based on distribution functionals, which replace the density operator and involve Grassmann fields representing anti-commuting fermion field annihilation, creation operators. It is an extension of a previous phase space theory paper for fermions (Paper I) based on separate modes, in which the density operator is replaced by a distribution function depending on Grassmann phase space variables which represent the mode annihilation and creation operators. This further development of the theory is important for the situation when large numbers of fermions are involved, resulting in too many modes to treat separately. Here Grassmann fields, distribution functionals, functional Fokker–Planck equations and Ito stochastic field equations are involved. Typical applications to a trapped Fermi gas of interacting spin 1/2 fermionic atoms and to multi-component Fermi gases with non-zero range interactions are presented, showing that the Ito stochastic field equations are local in these cases. For the spin 1/2 case we also show how simple solutions can be obtained both for the untrapped case and for an optical lattice trapping potential.
Two-level method with coarse space size independent convergence
Energy Technology Data Exchange (ETDEWEB)
Vanek, P.; Brezina, M. [Univ. of Colorado, Denver, CO (United States); Tezaur, R.; Krizkova, J. [UWB, Plzen (Czech Republic)
1996-12-31
The basic disadvantage of the standard two-level method is the strong dependence of its convergence rate on the size of the coarse-level problem. In order to obtain the optimal convergence result, one is limited to using a coarse space which is only a few times smaller than the size of the fine-level one. Consequently, the asymptotic cost of the resulting method is the same as in the case of using a coarse-level solver for the original problem. Today`s two-level domain decomposition methods typically offer an improvement by yielding a rate of convergence which depends on the ratio of fine and coarse level only polylogarithmically. However, these methods require the use of local subdomain solvers for which straightforward application of iterative methods is problematic, while the usual application of direct solvers is expensive. We suggest a method diminishing significantly these difficulties.
A new method to culture sweetpotato in space farming
Tsuyuki, I.; Ishii, Y.; Oda, M.; Kitaya, Y.; Mori, G.
Sweetpotato production in space has many advantages over that of other crops; the plant has a higher growth rate and a higher yield with less fertilizer and less water, and functions as an efficient CO_2/O_2 converter. In a limited space in space farming, however, it is not favorable that sweetpotato shoots develop vigorously while the roots have not enlarged yet, because the sweetpotato organ of interest is not the shoot but the tuberous root. Cuttings of sweetpotato (Ipomoea batatas Lam. "Beniazuma") were used in this study. Each cutting was cut off from the 2nd - 10th nodes from the apices of mother branches and consisted of one expanded leaf, one node and five cm long stem. The cuttings were cultured suboptimally on a mixed soil (peat-moss:vermiculite=1:1 in volume) in a greenhouse under sunlight. Growth characteristics of the cuttings removed axillary buds were compared with cuttings with axillary buds in the first experiment. The cuttings without axillary buds started tuberous root bulking about 30 days after the onset of the experiment. The harvest index (tuberous root dry mass/total dry mass) was 0.5 after 70 days. Whereas, the control plant with an axillary bud developed a lateral shoot and formed no tuberous root during 70 days in the experiment. It was necessary to remove the axillary buds in order to form the tuberous roots in this method. To evaluate the effect of light intensity on tuberous root formation, cuttings without axillary buds were shaded with cheesecloth having 43% of light transmittance in the second experiment. The tuberous root formation was retarded 50 days in shaded cuttings compared with control cuttings. The tuberous roots were quickly formed and the large harvest index was ensured in this method with cuttings without axillary buds. Therefore the method is expected to be advantageous to culture sweetpotato at a high density with rapid turn over in a limited culture space in space farming.
Space Environment Modelling with the Use of Artificial Intelligence Methods
Lundstedt, H.; Wintoft, P.; Wu, J.-G.; Gleisner, H.; Dovheden, V.
1996-12-01
Space based technological systems are affected by the space weather in many ways. Several severe failures of satellites have been reported at times of space storms. Our society also increasingly depends on satellites for communication, navigation, exploration, and research. Predictions of the conditions in the satellite environment have therefore become very important. We will here present predictions made with the use of artificial intelligence (AI) techniques, such as artificial neural networks (ANN) and hybrids of AT methods. We are developing a space weather model based on intelligence hybrid systems (IHS). The model consists of different forecast modules, each module predicts the space weather on a specific time-scale. The time-scales range from minutes to months with the fundamental time-scale of 1-5 minutes, 1-3 hours, 1-3 days, and 27 days. Solar and solar wind data are used as input data. From solar magnetic field measurements, either made on the ground at Wilcox Solar Observatory (WSO) at Stanford, or made from space by the satellite SOHO, solar wind parameters can be predicted and modelled with ANN and MHD models. Magnetograms from WSO are available on a daily basis. However, from SOHO magnetograms will be available every 90 minutes. SOHO magnetograms as input to ANNs will therefore make it possible to even predict solar transient events. Geomagnetic storm activity can today be predicted with very high accuracy by means of ANN methods using solar wind input data. However, at present real-time solar wind data are only available during part of the day from the satellite WIND. With the launch of ACE in 1997, solar wind data will on the other hand be available during 24 hours per day. The conditions of the satellite environment are not only disturbed at times of geomagnetic storms but also at times of intense solar radiation and highly energetic particles. These events are associated with increased solar activity. Predictions of these events are therefore
The class as space and fundamental method for educational guidance
Directory of Open Access Journals (Sweden)
Irela Margarita Paz-Domínguez
2016-11-01
Full Text Available Educational guidance is a function of professional education that is still blurred in the pedagogical theory and practice, as has been subsumed by the methodological and research teaching function, as well as being valued by many as specific task of psycho pedagogues, counselors and psychologists. This article is the result of a theoretical study aims to argue the role of educational guidance as a function of teaching, highlighting the class as space and fundamental method in it. Were used for this purpose, theoretical methods of analysis-synthesis, induction-deduction and dialectic hermeneutical, which it was the precision of ideas around the class as space sociological, psychological and pedagogical partner especially for the orientation and way peculiar that favors such a process, if personal and group learners resources for the development of his personality are promoted from class.
Statistical learning modeling method for space debris photometric measurement
Sun, Wenjing; Sun, Jinqiu; Zhang, Yanning; Li, Haisen
2016-03-01
Photometric measurement is an important way to identify the space debris, but the present methods of photometric measurement have many constraints on star image and need complex image processing. Aiming at the problems, a statistical learning modeling method for space debris photometric measurement is proposed based on the global consistency of the star image, and the statistical information of star images is used to eliminate the measurement noises. First, the known stars on the star image are divided into training stars and testing stars. Then, the training stars are selected as the least squares fitting parameters to construct the photometric measurement model, and the testing stars are used to calculate the measurement accuracy of the photometric measurement model. Experimental results show that, the accuracy of the proposed photometric measurement model is about 0.1 magnitudes.
Singular perturbation method for evolution equations in Banach spaces
International Nuclear Information System (INIS)
Mika, J.
1976-01-01
The singular perturbation method is applied to linear evolution equations in Banach spaces containing a small parameter multiplying the time derivative. Outer and inner asymptotic solutions are formulated and the sense in which they converge to the exact solution is rigorously defined. It is then shown that the sum of the two asymptotic solutions converges uniformly to the exact solution. Possible applications to various physical situations are indicated. (Auth.)
Forecasting space weather: Can new econometric methods improve accuracy?
Reikard, Gordon
2011-06-01
Space weather forecasts are currently used in areas ranging from navigation and communication to electric power system operations. The relevant forecast horizons can range from as little as 24 h to several days. This paper analyzes the predictability of two major space weather measures using new time series methods, many of them derived from econometrics. The data sets are the A p geomagnetic index and the solar radio flux at 10.7 cm. The methods tested include nonlinear regressions, neural networks, frequency domain algorithms, GARCH models (which utilize the residual variance), state transition models, and models that combine elements of several techniques. While combined models are complex, they can be programmed using modern statistical software. The data frequency is daily, and forecasting experiments are run over horizons ranging from 1 to 7 days. Two major conclusions stand out. First, the frequency domain method forecasts the A p index more accurately than any time domain model, including both regressions and neural networks. This finding is very robust, and holds for all forecast horizons. Combining the frequency domain method with other techniques yields a further small improvement in accuracy. Second, the neural network forecasts the solar flux more accurately than any other method, although at short horizons (2 days or less) the regression and net yield similar results. The neural net does best when it includes measures of the long-term component in the data.
A Method to Overcome Space Charge at Injection
International Nuclear Information System (INIS)
Ya. Derbenev
2005-01-01
The transverse space charge forces in a high current, low energy beam can be reduced by mean of a large increase of the beam's transverse sizes while maintaining the beam area in the 4D phase space. This can be achieved by transforming the beam area in phase space of each of two normal 2D transverse (either plane or circular) modes from a spot shape into a narrow ring of a large amplitude, but homogeneous in phase. Such a transformation results from the beam evolution in the island of a dipole resonance when the amplitude width of the island shrinks adiabatically. After stacking (by using stripping foils or cooling) the beam in such a state and accelerating to energies sufficiently high that the space charge becomes insignificant, the beam then can be returned back to a normal spot shape by applying the reverse transformation. An arrangement that can provide such beam gymnastics along a transport line after a linac and before a booster and/or in a ring with circulating beam will be described and numerical estimates will be presented. Other potential applications of the method will be briefly discussed
Exploration of Stellarator Configuration Space with Global Search Methods
International Nuclear Information System (INIS)
Mynick, H.E.; Pomphrey, N.; Ethier, S.
2001-01-01
An exploration of stellarator configuration space z for quasi-axisymmetric stellarator (QAS) designs is discussed, using methods which provide a more global view of that space. To this end, we have implemented a ''differential evolution'' (DE) search algorithm in an existing stellarator optimizer, which is much less prone to become trapped in local, suboptimal minima of the cost function chi than the local search methods used previously. This search algorithm is complemented by mapping studies of chi over z aimed at gaining insight into the results of the automated searches. We find that a wide range of the attractive QAS configurations previously found fall into a small number of classes, with each class corresponding to a basin of chi(z). We develop maps on which these earlier stellarators can be placed, the relations among them seen, and understanding gained into the physics differences between them. It is also found that, while still large, the region of z space containing practically realizable QAS configurations is much smaller than earlier supposed
High Performance Parallel Methods for Space Weather Simulations
Hunter, Paul (Technical Monitor); Gombosi, Tamas I.
2003-01-01
This is the final report of our NASA AISRP grant entitled 'High Performance Parallel Methods for Space Weather Simulations'. The main thrust of the proposal was to achieve significant progress towards new high-performance methods which would greatly accelerate global MHD simulations and eventually make it possible to develop first-principles based space weather simulations which run much faster than real time. We are pleased to report that with the help of this award we made major progress in this direction and developed the first parallel implicit global MHD code with adaptive mesh refinement. The main limitation of all earlier global space physics MHD codes was the explicit time stepping algorithm. Explicit time steps are limited by the Courant-Friedrichs-Lewy (CFL) condition, which essentially ensures that no information travels more than a cell size during a time step. This condition represents a non-linear penalty for highly resolved calculations, since finer grid resolution (and consequently smaller computational cells) not only results in more computational cells, but also in smaller time steps.
Delange, Pascal; Backes, Steffen; van Roekeghem, Ambroise; Pourovskii, Leonid; Jiang, Hong; Biermann, Silke
2018-04-01
The most intriguing properties of emergent materials are typically consequences of highly correlated quantum states of their electronic degrees of freedom. Describing those materials from first principles remains a challenge for modern condensed matter theory. Here, we review, apply and discuss novel approaches to spectral properties of correlated electron materials, assessing current day predictive capabilities of electronic structure calculations. In particular, we focus on the recent Screened Exchange Dynamical Mean-Field Theory scheme and its relation to generalized Kohn-Sham Theory. These concepts are illustrated on the transition metal pnictide BaCo2As2 and elemental zinc and cadmium.
On High Dimensional Searching Spaces and Learning Methods
DEFF Research Database (Denmark)
Yazdani, Hossein; Ortiz-Arroyo, Daniel; Choros, Kazimierz
2017-01-01
for the upper and lower boundaries for data objects with respect to each cluster. BFPM facilitates algorithms to converge and also inherits the abilities of conventional fuzzy and possibilistic methods. In Big Data applications knowing the exact type of data objects and selecting the most accurate similarity [1......In data science, there are important parameters that affect the accuracy of the algorithms used. Some of these parameters are: the type of data objects, the membership assignments, and distance or similarity functions. In this chapter we describe different data types , membership functions...... , and similarity functions and discuss the pros and cons of using each of them. Conventional similarity functions evaluate objects in the vector space. Contrarily, Weighted Feature Distance (WFD) functions compare data objects in both feature and vector spaces, preventing the system from being affected by some...
A new method for mapping perceptual biases across visual space.
Finlayson, Nonie J; Papageorgiou, Andriani; Schwarzkopf, D Samuel
2017-08-01
How we perceive the environment is not stable and seamless. Recent studies found that how a person qualitatively experiences even simple visual stimuli varies dramatically across different locations in the visual field. Here we use a method we developed recently that we call multiple alternatives perceptual search (MAPS) for efficiently mapping such perceptual biases across several locations. This procedure reliably quantifies the spatial pattern of perceptual biases and also of uncertainty and choice. We show that these measurements are strongly correlated with those from traditional psychophysical methods and that exogenous attention can skew biases without affecting overall task performance. Taken together, MAPS is an efficient method to measure how an individual's perceptual experience varies across space.
A comparison of tagging methods and their tagging space.
Ke, Xiayi; Miretti, Marcos M; Broxholme, John; Hunt, Sarah; Beck, Stephan; Bentley, David R; Deloukas, Panos; Cardon, Lon R
2005-09-15
Single-nucleotide polymorphism (SNP) tagging is widely used as a way of saving genotyping costs in association studies. A number of different tagging methods have been developed to reduce the number of markers to be genotyped while maintaining power for detecting effects on non-assayed SNPs. How the different methods perform in different settings, the degree to which they overlap and share common tags and how they differ are important questions. We investigated these questions by comparing three widely used tagging methods/algorithms--one haplotype r2-based method, one pair-wise r2-based method and one method which was based on haplotype diversity but focused on major haplotypes. Tagging efficiency was defined as the number of genotyped markers divided by the number of tagging SNPs. Tagging effectiveness was defined as the proportion of un-genotyped or 'hidden' SNPs being detected (having a pair-wise or haplotype r2 with a set of tagging SNPs over a threshold, e.g. haplotype r2> or =0.80). The ENCODE regions genotyped on the HapMap CEPH individuals were examined in this study. Tagging effectiveness was generally poor for rare SNPs than for common SNPs, for all three tagging methods. Inclusion of rare SNPs into initial HapMap scheme could enhance the performance of tags on rare hidden SNPs at the expense of increased genotyping cost. At a moderate tagging efficiency, more than 90% of hidden SNPs detected by tagging SNPs selected by one method were also detected by tagging SNPs selected by another method, and this figure could be increased to 100% if tagging efficiency was allowed to drop. These results indicate that the tagging space is highly concordant between different tagging methods, despite the fact that they often involve different sets of tagging SNPs.
Grassmann phase space methods for fermions. I. Mode theory
Dalton, B. J.; Jeffers, J.; Barnett, S. M.
2016-07-01
In both quantum optics and cold atom physics, the behaviour of bosonic photons and atoms is often treated using phase space methods, where mode annihilation and creation operators are represented by c-number phase space variables, with the density operator equivalent to a distribution function of these variables. The anti-commutation rules for fermion annihilation, creation operators suggest the possibility of using anti-commuting Grassmann variables to represent these operators. However, in spite of the seminal work by Cahill and Glauber and a few applications, the use of Grassmann phase space methods in quantum-atom optics to treat fermionic systems is rather rare, though fermion coherent states using Grassmann variables are widely used in particle physics. The theory of Grassmann phase space methods for fermions based on separate modes is developed, showing how the distribution function is defined and used to determine quantum correlation functions, Fock state populations and coherences via Grassmann phase space integrals, how the Fokker-Planck equations are obtained and then converted into equivalent Ito equations for stochastic Grassmann variables. The fermion distribution function is an even Grassmann function, and is unique. The number of c-number Wiener increments involved is 2n2, if there are n modes. The situation is somewhat different to the bosonic c-number case where only 2 n Wiener increments are involved, the sign of the drift term in the Ito equation is reversed and the diffusion matrix in the Fokker-Planck equation is anti-symmetric rather than symmetric. The un-normalised B distribution is of particular importance for determining Fock state populations and coherences, and as pointed out by Plimak, Collett and Olsen, the drift vector in its Fokker-Planck equation only depends linearly on the Grassmann variables. Using this key feature we show how the Ito stochastic equations can be solved numerically for finite times in terms of c-number stochastic
Hierarchical N-body methods on shared address space multiprocessors.
Holt, C.; Singh, J. P.
The authors examine the parallelization issues in and architectural implications of the two dominant adaptive hierarchical N-body methods: the Barnes-Hut method and the Fast Multipole Method. They show that excellent parallel performance can be obtained on cache-coherent shared address space multiprocessors, by demonstrating performance on three cache-coherent machines: the Stanford DASH, the Kendall Square Research KSR-1, and the Silicon Graphics Challenge. Even on machines that have their main memory physically distributed among processing nodes and highly nonuniform memory access costs, the speedups are obtained without any attention to where memory is allocated on the machine. The authors show that the reason for good performance is the high degree of temporal locality afforded by the applications, and the fact that working sets are small (and scale slowly) so that caching shared data automatically in hardware exploits this locality very effectively. Even if data distribution in main memory is assumed to be free, it does not help very much. Finally, they address a potential bottleneck in scaling the parallelism to large machines, namely the fraction of time spent in building the tree used by hierarchical N-body methods.
Phonon Calculations Using the Real-Space Multigrid Method (RMG)
Zhang, Jiayong; Lu, Wenchang; Briggs, Emil; Cheng, Yongqiang; Ramirez-Cuesta, A. J.; Bernholc, Jerry
RMG, a DFT-based open-source package using the real-space multigrid method, has proven to work effectively on large scale systems with thousands of atoms. Our recent work has shown its practicability for high accuracy phonon calculations employing the frozen phonon method. In this method, a primary unit cell with a small lattice constant is enlarged to a supercell that is sufficiently large to obtain the force constants matrix by finite displacements of atoms in the supercell. An open-source package PhonoPy is used to determine the necessary displacements by taking symmetry into account. A python script coupling RMG and PhonoPy enables us to perform high-throughput calculations of phonon properties. We have applied this method to many systems, such as silicon, silica glass, ZIF-8, etc. Results from RMG are compared to the experimental spectra measured using the VISION inelastic neutron scattering spectrometer at the Spallation Neutron Source at ORNL, as well as results from other DFT codes. The computing resources were made available through the VirtuES (Virtual Experiments in Spectroscopy) project, funded by Laboratory Directed Research and Development program (LDRD project No. 7739)
High-Order Space-Time Methods for Conservation Laws
Huynh, H. T.
2013-01-01
Current high-order methods such as discontinuous Galerkin and/or flux reconstruction can provide effective discretization for the spatial derivatives. Together with a time discretization, such methods result in either too small a time step size in the case of an explicit scheme or a very large system in the case of an implicit one. To tackle these problems, two new high-order space-time schemes for conservation laws are introduced: the first is explicit and the second, implicit. The explicit method here, also called the moment scheme, achieves a Courant-Friedrichs-Lewy (CFL) condition of 1 for the case of one-spatial dimension regardless of the degree of the polynomial approximation. (For standard explicit methods, if the spatial approximation is of degree p, then the time step sizes are typically proportional to 1/p(exp 2)). Fourier analyses for the one and two-dimensional cases are carried out. The property of super accuracy (or super convergence) is discussed. The implicit method is a simplified but optimal version of the discontinuous Galerkin scheme applied to time. It reduces to a collocation implicit Runge-Kutta (RK) method for ordinary differential equations (ODE) called Radau IIA. The explicit and implicit schemes are closely related since they employ the same intermediate time levels, and the former can serve as a key building block in an iterative procedure for the latter. A limiting technique for the piecewise linear scheme is also discussed. The technique can suppress oscillations near a discontinuity while preserving accuracy near extrema. Preliminary numerical results are shown
Hilbert asymptotic expansion method for evolution equations in Banach spaces
International Nuclear Information System (INIS)
Mika, J.
1978-01-01
In the paper an abstract initial value problem for a singularly perturbed linear evolution equation in a Banach space is considered. The evolution operator consists of two operators. One of them having an eigenvalue at the origin is multiplied by 1/epsilon where epsilon is a small positive parameter. The Hilbert expansion method is applied to solving the problem and the asymptotic solution is shown to converge uniformly to the exact one with epsilon tending to zero. The results of the paper are applicable to the linear Boltzmann equation if the scattering operator is bounded and the streaming operator is represented in the finite-differnce form. As an example, the Boltzmann equation for neutrons is considered and the Hilbert expansion used to derive the diffusion equation. (author)
Recursion method in the k-space representation
International Nuclear Information System (INIS)
Anlage, S.M.; Smith, D.L.
1986-01-01
We show that by using a unitary transformation to k space and the special-k-point method for evaluating Brillouin-zone sums, the recursion method can be very effectively applied to translationally invariant systems. We use this approach to perform recursion calculations for realistic tight-binding Hamiltonians which describe diamond- and zinc-blende-structure semiconductors. Projected densities of states for these Hamiltonians have band gaps and internal van Hove singularities. We calculate coefficients for 63 recursion levels exactly and for about 200 recursion levels to a good approximation. Comparisons are made for materials with different magnitude band gaps (diamond, Si, α-Sn). Comparison is also made between materials with one (e.g., diamond) and two (e.g., GaAs) band gaps. The asymptotic behavior of the recursion coefficients is studied by Fourier analysis. Band gaps in the projected density of states dominate the asymptotic behavior. Perturbation analysis describes the asymptotic behavior rather well. Projected densities of states are calculated using a very simple termination scheme. These densities of states compare favorably with the results of Gilat-Raubenheimer integration
Low Cost Method of Manufacturing Space Optics, Phase I
National Aeronautics and Space Administration — Proposed is the development of a manufacturing technology that will increase feasible large optics design options and significantly reduce the manufacturing time,...
Two methods of space--time energy densification
International Nuclear Information System (INIS)
Sahlin, R.L.
1976-01-01
With a view to the goal of net energy production from a DT microexplosion, we study two ideas (methods) through which (separately or in combination) energy may be ''concentrated'' into a small volume and short period of time--the so-called space-time energy densification or compression. We first discuss the advantages and disadvantages of lasers and relativistic electron-beam (E-beam) machines as the sources of such energy and identify the amplification of laser pulses as a key factor in energy compression. The pulse length of present relativistic E-beam machines is the most serious limitation of this pulsed-power source. The first energy-compression idea we discuss is the reasonably efficient production of short-duration, high-current relativistic electron pulses by the self interruption and restrike of a current in a plasma pinch due to the rapid onset of strong turbulence. A 1-MJ plasma focus based on this method is nearing completion at this Laboratory. The second energy-compression idea is based on laser-pulse production through the parametric amplification of a self-similar or solitary wave pulse, for which analogs can be found in other wave processes. Specifically, the second energy-compression idea is a proposal for parametric amplification of a solitary, transverse magnetic pulse in a coaxial cavity with a Bennett dielectric rod as an inner coax. Amplifiers of this type can be driven by the pulsed power from a relativistic E-beam machine. If the end of the inner dielectric coax is made of LiDT or another fusionable material, the amplified pulse can directly drive a fusion reaction--there would be no need to switch the pulse out of the system toward a remote target
Two methods of space-time energy densification
International Nuclear Information System (INIS)
Sahlin, H.L.
1975-01-01
With a view to the goal of net energy production from a DT microexplosion, two ideas (methods) are studied through which (separately or in combination) energy may be ''concentrated'' into a small volume and short period of time--the so-called space-time energy densification or compression. The advantages and disadvantages of lasers and relativistic electron-beam (E-beam) machines as the sources of such energy are studied and the amplification of laser pulses as a key factor in energy compression is discussed. The pulse length of present relativistic E-beam machines is the most serious limitation of this pulsed-power source. The first energy-compression idea discussed is the reasonably efficient production of short-duration, high-current relativistic electron pulses by the self interruption and restrike of a current in a plasma pinch due to the rapid onset of strong turbulence. A 1-MJ plasma focus based on this method is nearing completion at this Laboratory. The second energy-compression idea is based on laser-pulse production through the parametric amplification of a self-similar or solitary wave pulse, for which analogs can be found in other wave processes. Specifically, the second energy-compression idea is a proposal for parametric amplification of a solitary, transverse magnetic pulse in a coaxial cavity with a Bennett dielectric rod as an inner coax. Amplifiers of this type can be driven by the pulsed power from a relativistic E-beam machine. If the end of the inner dielectric coax is made of LiDT or another fusionable material, the amplified pulse can directly drive a fusion reaction--there would be no need to switch the pulse out of the system toward a remote target. (auth)
Computational methods for microfluidic microscopy and phase-space imaging
Pegard, Nicolas Christian Richard
Modern optical devices are made by assembling separate components such as lenses, objectives, and cameras. Traditionally, each part is optimized separately, even though the trade-offs typically limit the performance of the system overall. This component-based approach is particularly unfit to solve the new challenges brought by modern biology: 3D imaging, in vivo environments, and high sample throughput. In the first part of this thesis, we introduce a general method to design integrated optical systems. The laws of wave propagation, the performance of available technology, as well as other design parameters are combined as constraints into a single optimization problem. The solution provides qualitative design rules to improve optical systems as well as quantitative task-specific methods to minimize loss of information. Our results have applications in optical data storage, holography, and microscopy. The second part of this dissertation presents a direct application. We propose a more efficient design for wide-field microscopy with coherent light, based on double transmission through the sample. Historically, speckle noise and aberrations caused by undesired interferences have made coherent illumination unpopular for imaging. We were able to dramatically reduce speckle noise and unwanted interferences using optimized holographic wavefront reconstruction. The resulting microscope not only yields clear coherent images with low aberration---even in thick samples---but also increases contrast and enables optical filtering and in-depth sectioning. In the third part, we develop new imaging techniques that better respond to the needs of modern biology research through implementing optical design optimization. Using a 4D phase-space distribution, we first represent the state and propagation of incoherent light. We then introduce an additional degree of freedom by putting samples in motion in a microfluidic channel, increasing image diversity. From there, we develop a
Open Problem: Kernel methods on manifolds and metric spaces
DEFF Research Database (Denmark)
Feragen, Aasa; Hauberg, Søren
2016-01-01
Radial kernels are well-suited for machine learning over general geodesic metric spaces, where pairwise distances are often the only computable quantity available. We have recently shown that geodesic exponential kernels are only positive definite for all bandwidths when the input space has strong...... linear properties. This negative result hints that radial kernel are perhaps not suitable over geodesic metric spaces after all. Here, however, we present evidence that large intervals of bandwidths exist where geodesic exponential kernels have high probability of being positive definite over finite...... datasets, while still having significant predictive power. From this we formulate conjectures on the probability of a positive definite kernel matrix for a finite random sample, depending on the geometry of the data space and the spread of the sample....
Low Cost Method of Manufacturing Space Optics Project
National Aeronautics and Space Administration — The Phase I project successfully demonstrated the feasibility of developing a technology that will reduce cost and manufacturing time, broaden design options, and...
The method of moments and nested Hilbert spaces in quantum mechanics
International Nuclear Information System (INIS)
Adeniyi Bangudu, E.
1980-08-01
It is shown how the structures of a nested Hilbert space Hsub(I), associated with a given Hilbert space Hsub(O), may be used to simplify our understanding of the effects of parameters, whose values have to be chosen rather than determined variationally, in the method of moments. The result, as applied to non-relativistic quartic oscillator and helium atom, is to associate the parameters with sequences of Hilbert spaces, while the error of the method of moments relative to the variational method corresponds to a nesting operator of the nested Hilbert space. Difficulties hindering similar interpretations in terms of rigged Hilbert space structures are highlighted. (author)
Application of nuclear-physics methods in space materials science
Novikov, L. S.; Voronina, E. N.; Galanina, L. I.; Chirskaya, N. P.
2017-07-01
The brief history of the development of investigations at the Skobeltsyn Institute of Nuclear Physics, Moscow State University (SINP MSU) in the field of space materials science is outlined. A generalized scheme of a numerical simulation of the radiation impact on spacecraft materials and elements of spacecraft equipment is examined. The results obtained by solving some of the most important problems that modern space materials science should address in studying nuclear processes, the interaction of charged particles with matter, particle detection, the protection from ionizing radiation, and the impact of particles on nanostructures and nanomaterials are presented.
A Sweep-Line Method for State Space Exploration
DEFF Research Database (Denmark)
Christensen, Søren; Kristensen, Lars Michael; Mailund, Thomas
2001-01-01
generation, since these states can never be reached again. This in turn reduces the memory used for state space storage during the task of verification. Examples of progress measures are sequence numbers in communication protocols and time in certain models with time. We illustrate the application...
Lyman, Katie J; Keister, Kassiann; Gange, Kara; Mellinger, Christopher D; Hanson, Thomas A
2017-04-01
Limited quantitative, physiological evidence exists regarding the effectiveness of Kinesio® Taping methods, particularly with respect to the potential ability to impact underlying physiological joint space and structures. To better understand the impact of these techniques, the underlying physiological processes must be investigated in addition to the examination of more subjective measures related to pain in unhealthy tissues. The purpose of this study was to determine whether the Kinesio® Taping Space Correction Method created a significant difference in patellofemoral joint space, as quantified by diagnostic ultrasound. Pre-test/post-test prospective cohort study. Thirty-two participants with bilaterally healthy knees and no past history of surgery took part in the study. For each participant, diagnostic ultrasound was utilized to collect three measurements: the patellofemoral joint space, the distance from the skin to the superficial patella, and distance from the skin to the patellar tendon. The Kinesio® Taping Space Correction Method was then applied. After a ten-minute waiting period in a non-weight bearing position, all three measurements were repeated. Each participant served as his or her own control. Paired t tests showed a statistically significant difference (mean difference = 1.1 mm, t [3,1] = 2.823, p = 0.008, g = .465) between baseline and taped conditions in the space between the posterior surface of the patella to the medial femoral condyle. Neither the distance from the skin to the superficial patella nor the distance from the skin to the patellar tendon increased to a statistically significant degree. The application of the Kinesio® Taping Space Correction Method increases the patellofemoral joint space in healthy adults by increasing the distance between the patella and the medial femoral condyle, though it does not increase the distance from the skin to the superficial patella nor to the patellar tendon. 3.
Radiation reaction in curved space-time:. local method
Gal'Tsov, Dmitri; Spirin, Pavel; Staub, Simona
Although consensus seems to exist about the validity of equations accounting for radiation reaction in curved space-time, their previous derivations were criticized recently as not fully satisfactory: some ambiguities were noticed in the procedure of integration of the field momentum over the tube surrounding the world-line. To avoid these problems we suggest a purely local derivation dealing with the field quantities defined only on the world-line. We consider point particle interacting with scalar, vector (electromagnetic) and linearized gravitational fields in the (generally non-vacuum) curved space-time. To properly renormalize the self-action in the gravitational case, we use a manifestly reparameterization-invariant formulation of the theory. Scalar and vector divergences are shown to cancel for a certain ratio of the corresponding charges. We also report on a modest progress in extending the results for the gravitational radiation reaction to the case of non-vacuum background.
Methods for Intelligent Mapping of the IPV6 Address Space
2015-03-01
combat cyber threats, just as we have done to combat terrorism . [3] In IPv4, that intelligence included a fundamental understanding of how networks...countries abroad. Peru , Norway, Germany, China, Japan, Belgium, and Malaysia all show significant increases in IPv6 adoption, while several match or...accurate. 5.3 Concluding Remarks With the imminent exhaustion of the IPv4 address space, adoption of IPv6 is occurring at a rapid pace. As systems migrate
Homotopy deform method for reproducing kernel space for ...
Indian Academy of Sciences (India)
2016-09-23
Sep 23, 2016 ... Nonlinear differential equations; the homotopy deform method; the simplified reproducing kernel ... an equivalent integro differential equation. ... an algorithm for solving nonlinear multipoint BVPs by combining homotopy perturbation and variational iteration methods. Most recently, Duan and Rach [12].
Introduction to partial differential equations and Hilbert space methods
Gustafson, Karl E
1997-01-01
Easy-to-use text examines principal method of solving partial differential equations, 1st-order systems, computation methods, and much more. Over 600 exercises, with answers for many. Ideal for a 1-semester or full-year course.
Homotopy deform method for reproducing kernel space for ...
Indian Academy of Sciences (India)
In this paper, the combination of homotopy deform method (HDM) and simplified reproducing kernel method (SRKM) is introduced for solving the boundary value problems (BVPs) of nonlinear differential equations. The solution methodology is based on Adomian decomposition and reproducing kernel method (RKM).
Blanchard, Philippe
2015-01-01
The second edition of this textbook presents the basic mathematical knowledge and skills that are needed for courses on modern theoretical physics, such as those on quantum mechanics, classical and quantum field theory, and related areas. The authors stress that learning mathematical physics is not a passive process and include numerous detailed proofs, examples, and over 200 exercises, as well as hints linking mathematical concepts and results to the relevant physical concepts and theories. All of the material from the first edition has been updated, and five new chapters have been added on such topics as distributions, Hilbert space operators, and variational methods. The text is divided into three main parts. Part I is a brief introduction to distribution theory, in which elements from the theories of ultradistributions and hyperfunctions are considered in addition to some deeper results for Schwartz distributions, thus providing a comprehensive introduction to the theory of generalized functions. P...
Convex optimization in normed spaces theory, methods and examples
Peypouquet, Juan
2015-01-01
This work is intended to serve as a guide for graduate students and researchers who wish to get acquainted with the main theoretical and practical tools for the numerical minimization of convex functions on Hilbert spaces. Therefore, it contains the main tools that are necessary to conduct independent research on the topic. It is also a concise, easy-to-follow and self-contained textbook, which may be useful for any researcher working on related fields, as well as teachers giving graduate-level courses on the topic. It will contain a thorough revision of the extant literature including both classical and state-of-the-art references.
Method for Ground-to-Space Laser Calibration System
Lukashin, Constantine (Inventor); Wielicki, Bruce A. (Inventor)
2014-01-01
The present invention comprises an approach for calibrating the sensitivity to polarization, optics degradation, spectral and stray light response functions of instruments on orbit. The concept is based on using an accurate ground-based laser system, Ground-to-Space Laser Calibration (GSLC), transmitting laser light to instrument on orbit during nighttime substantially clear-sky conditions. To minimize atmospheric contribution to the calibration uncertainty the calibration cycles should be performed in short time intervals, and all required measurements are designed to be relative. The calibration cycles involve ground operations with laser beam polarization and wavelength changes.
An Asymmetrical Space Vector Method for Single Phase Induction Motor
DEFF Research Database (Denmark)
Cui, Yuanhai; Blaabjerg, Frede; Andersen, Gert Karmisholt
2002-01-01
Single phase induction motors are the workhorses in low-power applications in the world, and also the variable speed is necessary. Normally it is achieved either by the mechanical method or by controlling the capacitor connected with the auxiliary winding. Any above method has some drawback which...
Signal processing using methods of dimensionality reduction of representation space
Popovskiy, V. V.
2003-01-01
The universal method of processing of signals with the help of downturn of their dimensions is considered. This work has methodical, generalizing nature, and is aimed at drawing the attention of specialist and scientist to the unity of the definitions and solutions of the problems, connected with N-dimensional presentation and confluent presentations.
Space-time discontinuous Galerkin method for parabolic problems in time-dependent domains
Janivita Joto Sudirham, J.J.S.; Sudirham, J.J.; van der Vegt, Jacobus J.W.; van Damme, Rudolf M.J.
2004-01-01
In this report a space-time discontinuous Galerkin (DG) finite element method for the solution of the advection-diffusion-reaction equation in time-dependent domains is presented and analyzed. The variational formulation is based on a combination of the space-time DG method developed by van der Vegt
Computer based methods for measurement of joint space width: update of an ongoing OMERACT project
Sharp, John T.; Angwin, Jane; Boers, Maarten; Duryea, Jeff; von Ingersleben, Gabriele; Hall, James R.; Kauffman, Joost A.; Landewé, Robert; Langs, Georg; Lukas, Cédric; Maillefert, Jean-Francis; Bernelot Moens, Hein J.; Peloschek, Philipp; Strand, Vibeke; van der Heijde, Désirée
2007-01-01
Computer-based methods of measuring joint space width (JSW) could potentially have advantages over scoring joint space narrowing, with regard to increased standardization, sensitivity, and reproducibility. In an early exercise, 4 different methods showed good agreement on measured change in JSW over
Exploring the Gendering of Space by Using Memory Work as a Reflexive Research Method
Directory of Open Access Journals (Sweden)
Lia Bryant
2007-09-01
Full Text Available How can memory work be used as a pathway to reflect on the situatedness of the researcher and field of inquiry? The key aim of this article is to contribute to knowledge about the gendering of space developed by feminist geographers by using memory work as a reflexive research method. The authors present a brief review of feminist literature that covers the local and global symbolic meanings of spaces and the power relations within which space is experienced. From the literature they interpret themes of the interconnections between space, place, and time; sexualization of public space; and the bodily praxis of using space. Memories of gendered bodies and landscapes, movement and restricted space, and the disrupting of space allow the exploration of conceptualizations within the literature as active, situated, fragmented, and contextualized.
Ivanic, Joseph
2003-11-01
In order to reduce the number of ineffective configurations in a priori generated configuration spaces, a direct configuration interaction method has been developed which limits the electron occupations of orbital groups making up a total active space. A wave function is specified by first partitioning an active space into an unrestricted number of orbital groups and second by providing limiting values, in the form of minima and maxima, for the electron occupancies of each group. The configuration interaction problem corresponding to all possible determinants satisfying these conditions is solved in a fully direct manner by the use of Slater-Condon expressions in conjunction with single and double replacements. This configuration interaction approach, termed occupation restricted multiple active space-configuration interaction, has also been linked with orbital optimization programs to produce the occupation restricted multiple active space-self consistent field method.
Fast State-Space Methods for Inferring Dendritic Synaptic Connectivity
2013-08-08
2.23) which we can sample from using Markov Chain Monte Carlo ( MCMC ) methods. In particular we use a Gibbs sampler that cyclically samples a, τ2 and (W...computationally more intensive than the LARS method, not only due to the computational cost of the MCMC sampling , but because we need to pre-compute the full M... sampling from the posterior (2.23), but it is known that heavy- tailed distributions, such as log-Normal, are a more realistic choice (Song et al
State Space Methods in Ox/SsfPack
Directory of Open Access Journals (Sweden)
Matteo M. Pelagatti
2011-05-01
Full Text Available The use of state space models and their inference is illustrated using the package SsfPack for Ox. After a rather long introduction that explains the use of SsfPack and many of its functions, four case-studies illustrate the practical implementation of the software to real world problems through short sample programs. The first case consists in the analysis of the well-known (at least to time series analysis experts Nile data with a local level model. The other case-studies deal with ARIMA and RegARIMA models applied to the (also well-known Airline time series, structural time series models applied to the Italian industrial production index and stochastic volatility models applied to the FTSE100 index. In all applications inference on the model (hyper- parameters is carried out by maximum likelihood, but in one case (stochastic volatility also an MCMC-based approach is illustrated. Cubic splines are covered in a very short example as well.
The Marker State Space (MSS method for classifying clinical samples.
Directory of Open Access Journals (Sweden)
Brian P Fallon
Full Text Available The development of accurate clinical biomarkers has been challenging in part due to the diversity between patients and diseases. One approach to account for the diversity is to use multiple markers to classify patients, based on the concept that each individual marker contributes information from its respective subclass of patients. Here we present a new strategy for developing biomarker panels that accounts for completely distinct patient subclasses. Marker State Space (MSS defines "marker states" based on all possible patterns of high and low values among a panel of markers. Each marker state is defined as either a case state or a control state, and a sample is classified as case or control based on the state it occupies. MSS was used to define multi-marker panels that were robust in cross validation and training-set/test-set analyses and that yielded similar classification accuracy to several other classification algorithms. A three-marker panel for discriminating pancreatic cancer patients from control subjects revealed subclasses of patients based on distinct marker states. MSS provides a straightforward approach for modeling highly divergent subclasses of patients, which may be adaptable for diverse applications.
Space-time multiscale methods for Large Eddy Simulation
Munts, E.A.
2006-01-01
The Variational Multiscale (VMS) method has appeared as a promising new approach to the Large Eddy Simulation (LES) of turbulent flows. The key advantage of the VMS approach is that it allows different subgrid-scale (SGS) modeling assumptions to be made at different ranges of the resolved scales.
Time and space efficient multi-method dispatching
DEFF Research Database (Denmark)
Alstrup, Stephen; Brodal, Gerth Stølting; Gørtz, Inge Li
2002-01-01
The dispatching problem for object oriented languages is the problem of determining the most specialized method to invoke for calls at run-time. This can be a critical component of execution performance. A number of recent results, including [Muthukrishnan and Müller SODA’96, Ferragina and Muthuk...
Comparing Value of Urban Green Space Using Contingent Valuation and Travel Cost Methods
Directory of Open Access Journals (Sweden)
Chintantya Dea
2018-01-01
Full Text Available Green urban open space are an important element of the city. They gives multiple benefits for social life, human health, biodiversity, air quality, carbon sequestration, and water management. Travel Cost Method (TCM and Contingent Valuation Method (CVM are the most frequently used method in various studies that assess environmental good and services in monetary term for valuing urban green space. Both of those method are determined the value of urban green space through willingness to pay (WTP for ecosystem benefit and collected data through direct interview and questionnaire. Findings of this study showed the weaknesses and strengths of both methods for valuing urban green space and provided factors influencing the probability of user’s willingness to pay in each method.
Comparing Value of Urban Green Space Using Contingent Valuation and Travel Cost Methods
Chintantya, Dea; Maryono
2018-02-01
Green urban open space are an important element of the city. They gives multiple benefits for social life, human health, biodiversity, air quality, carbon sequestration, and water management. Travel Cost Method (TCM) and Contingent Valuation Method (CVM) are the most frequently used method in various studies that assess environmental good and services in monetary term for valuing urban green space. Both of those method are determined the value of urban green space through willingness to pay (WTP) for ecosystem benefit and collected data through direct interview and questionnaire. Findings of this study showed the weaknesses and strengths of both methods for valuing urban green space and provided factors influencing the probability of user's willingness to pay in each method.
Real-space Kerker method for self-consistent calculation using non-orthogonal basis functions
International Nuclear Information System (INIS)
Shiihara, Yoshinori; Kuwazuru, Osamu; Yoshikawa, Nobuhiro
2008-01-01
We have proposed the real-space Kerker method for fast self-consistent-field calculations in real-space approaches using non-orthogonal basis functions. In large-scale systems with many atoms, the Kerker method is a very efficient way to prevent charge sloshing, which induces numerical instability during the self-consistent iterations. We construct the Kerker preconditioning matrix with non-orthogonal basis functions and the preconditioning is performed by solving linear equations. The proposed real-space Kerker method is identical to the method in reciprocal space, with the following two advantages: (i) the method is suitable for massively parallel computation since it does not use the fast Fourier transform. (ii) The preconditioning is performed in an acceptable computational time since time-consuming integration, including the exponential kernel, need not be performed, unlike the method used by Manninen et al (1975 Phys. Rev. B 12 4012)
Comparison of enclosed space detection system with conventional methods
International Nuclear Information System (INIS)
Kercel, S.W.; Baylor, V.M.; Labaj, L.E.
1997-01-01
Enclosed Space Detection System (ESDS) is a fast, inexpensive, and reliable device for detecting human occupants hidden in vehicles. Operation requires less than two minutes. ESDS is used to foil attempts at smuggling illegal aliens, terrorists, and escaping prisoners. It is being tested at nuclear weapons facilities and has been operated at several prisons and international border crossings. ESDS is the first practical electronic alternative to physical searches of vehicles for hidden passengers. At critical checkpoints, a thorough physical search of a single fully loaded truck requires a team of from two to six people, and may take as long as eight hours. Despite this level of security, experience has shown that the search can occasionally be foiled. Due to the enormous time and expense of thorough physical searches of vehicles, they are seldom conducted at any but the most critical of locations, simply leaving many sites vulnerable to crime and terrorism. Prior to the development of the ESDS, the only other effective alternative to physical search was the use of specially-trained canines, which can be vastly superior to the physical search in both time and accuracy. However, as discussed in this paper, canine inspection is not really a competitive substitute for ESDS because canine reliability (80% at most) is not as high as that of the ESDS (99%+), while the costs, training requirements, and operator skill needed are significantly higher with canines than with the ESDS. In addition, the ESDS has straightforward self-diagnostic tests to ensure the system is operating correctly; such tests are not currently available with either canine or human inspectors. ESDS offers an attractive supplement or alternative to meet current security requirements for vehicle searches at portals at government, nuclear, industrial, and other facilities where concealed persons may pose a threat either by entering or leaving
Comparison of enclosed space detection system with conventional methods
Energy Technology Data Exchange (ETDEWEB)
Kercel, S.W.; Baylor, V.M.; Labaj, L.E.
1997-09-01
Enclosed Space Detection System (ESDS) is a fast, inexpensive, and reliable device for detecting human occupants hidden in vehicles. Operation requires less than two minutes. ESDS is used to foil attempts at smuggling illegal aliens, terrorists, and escaping prisoners. It is being tested at nuclear weapons facilities and has been operated at several prisons and international border crossings. ESDS is the first practical electronic alternative to physical searches of vehicles for hidden passengers. At critical checkpoints, a thorough physical search of a single fully loaded truck requires a team of from two to six people, and may take as long as eight hours. Despite this level of security, experience has shown that the search can occasionally be foiled. Due to the enormous time and expense of thorough physical searches of vehicles, they are seldom conducted at any but the most critical of locations, simply leaving many sites vulnerable to crime and terrorism. Prior to the development of the ESDS, the only other effective alternative to physical search was the use of specially-trained canines, which can be vastly superior to the physical search in both time and accuracy. However, as discussed in this paper, canine inspection is not really a competitive substitute for ESDS because canine reliability (80% at most) is not as high as that of the ESDS (99%+), while the costs, training requirements, and operator skill needed are significantly higher with canines than with the ESDS. In addition, the ESDS has straightforward self-diagnostic tests to ensure the system is operating correctly; such tests are not currently available with either canine or human inspectors. ESDS offers an attractive supplement or alternative to meet current security requirements for vehicle searches at portals at government, nuclear, industrial, and other facilities where concealed persons may pose a threat either by entering or leaving.
Asymptotic Solutions of Time-Space Fractional Coupled Systems by Residual Power Series Method
Directory of Open Access Journals (Sweden)
Wenjin Li
2017-01-01
Full Text Available This paper focuses on the asymptotic solutions to time-space fractional coupled systems, where the fractional derivative and integral are described in the sense of Caputo derivative and Riemann-Liouville integral. We introduce the Residual Power Series (for short RPS method to construct the desired asymptotic solutions. Furthermore, we apply this method to some time-space fractional coupled systems. The simplicity and efficiency of RPS method are shown by the application.
Space-angle approximations in the variational nodal method
International Nuclear Information System (INIS)
Lewis, E. E.; Palmiotti, G.; Taiwo, T.
1999-01-01
The variational nodal method is formulated such that the angular and spatial approximations maybe examined separately. Spherical harmonic, simplified spherical harmonic, and discrete ordinate approximations are coupled to the primal hybrid finite element treatment of the spatial variables. Within this framework, two classes of spatial trial functions are presented: (1) orthogonal polynomials for the treatment of homogeneous nodes and (2) bilinear finite subelement trial functions for the treatment of fuel assembly sized nodes in which fuel-pin cell cross sections are represented explicitly. Polynomial and subelement trial functions are applied to benchmark water-reactor problems containing MOX fuel using spherical harmonic and simplified spherical harmonic approximations. The resulting accuracy and computing costs are compared
Multigrid method based on a space-time approach with standard coarsening for parabolic problems
S.R. Franco (Sebastião Romero); F.J. Gaspar Lorenz (Franscisco); M.A. Villela Pinto (Marcio Augusto); C. Rodrigo (Carmen)
2018-01-01
textabstractIn this work, a space-time multigrid method which uses standard coarsening in both temporal and spatial domains and combines the use of different smoothers is proposed for the solution of the heat equation in one and two space dimensions. In particular, an adaptive smoothing strategy,
Autogenic feedback training experiment: A preventative method for space motion sickness
Cowings, Patricia S.
1993-01-01
Space motion sickness is a disorder which produces symptoms similar to those of motion sickness on Earth. This syndrome has affected approximately 50 percent of all astronauts and cosmonauts exposed to microgravity in space, but it differs from what is commonly known as motion sickness in a number of critical ways. There is currently no ground-based method for predicting susceptibility to motion sickness in space. Antimotion sickness drugs have had limited success in preventing or counteracting symptoms in space, and frequently caused debilitating side effects. The objectives were: (1) to evaluate the effectiveness of Autogenic-Feedback Training as a countermeasure for space motion sickness; (2) to compare physiological data and in-flight symptom reports to ground-based motion sickness data; and (3) to predict susceptibility to space motion sickness based on pre-flight data of each treatment group crew member.
On Landweber–Kaczmarz methods for regularizing systems of ill-posed equations in Banach spaces
International Nuclear Information System (INIS)
Leitão, A; Alves, M Marques
2012-01-01
In this paper, iterative regularization methods of Landweber–Kaczmarz type are considered for solving systems of ill-posed equations modeled (finitely many) by operators acting between Banach spaces. Using assumptions of uniform convexity and smoothness on the parameter space, we are able to prove a monotony result for the proposed method, as well as to establish convergence (for exact data) and stability results (in the noisy data case). (paper)
The method of rigged spaces in singular perturbation theory of self-adjoint operators
Koshmanenko, Volodymyr; Koshmanenko, Nataliia
2016-01-01
This monograph presents the newly developed method of rigged Hilbert spaces as a modern approach in singular perturbation theory. A key notion of this approach is the Lax-Berezansky triple of Hilbert spaces embedded one into another, which specifies the well-known Gelfand topological triple. All kinds of singular interactions described by potentials supported on small sets (like the Dirac δ-potentials, fractals, singular measures, high degree super-singular expressions) admit a rigorous treatment only in terms of the equipped spaces and their scales. The main idea of the method is to use singular perturbations to change inner products in the starting rigged space, and the construction of the perturbed operator by the Berezansky canonical isomorphism (which connects the positive and negative spaces from a new rigged triplet). The approach combines three powerful tools of functional analysis based on the Birman-Krein-Vishik theory of self-adjoint extensions of symmetric operators, the theory of singular quadra...
Wang, Min
2017-06-01
This paper aims to establish the Tikhonov regularization method for generalized mixed variational inequalities in Banach spaces. For this purpose, we firstly prove a very general existence result for generalized mixed variational inequalities, provided that the mapping involved has the so-called mixed variational inequality property and satisfies a rather weak coercivity condition. Finally, we establish the Tikhonov regularization method for generalized mixed variational inequalities. Our findings extended the results for the generalized variational inequality problem (for short, GVIP( F, K)) in R^n spaces (He in Abstr Appl Anal, 2012) to the generalized mixed variational inequality problem (for short, GMVIP(F,φ , K)) in reflexive Banach spaces. On the other hand, we generalized the corresponding results for the generalized mixed variational inequality problem (for short, GMVIP(F,φ ,K)) in R^n spaces (Fu and He in J Sichuan Norm Univ (Nat Sci) 37:12-17, 2014) to reflexive Banach spaces.
A Summary of the Space-Time Conservation Element and Solution Element (CESE) Method
Wang, Xiao-Yen J.
2015-01-01
The space-time Conservation Element and Solution Element (CESE) method for solving conservation laws is examined for its development motivation and design requirements. The characteristics of the resulting scheme are discussed. The discretization of the Euler equations is presented to show readers how to construct a scheme based on the CESE method. The differences and similarities between the CESE method and other traditional methods are discussed. The strengths and weaknesses of the method are also addressed.
Blokhinov, Y. B.; Chernyavskiy, A. S.; Zheltov, S. Y.
2012-07-01
The technical problem of creating the new Russian version of an automatic Space Cargo Ship (SCS) for the International Space Station (ISS) is inseparably connected to the development of a digital video system for automatically measuring the SCS position relative to ISS in the process of spacecraft docking. This paper presents a method for estimating the orientation elements based on the use of a highly detailed digital model of the ISS. The input data are digital frames from a calibrated video system and the initial values of orientation elements, these can be estimated from navigation devices or by fast-and-rough viewpoint-dependent algorithm. Then orientation elements should be defined precisely by means of algorithmic processing. The main idea is to solve the exterior orientation problem mainly on the basis of contour information of the frame image of ISS instead of ground control points. A detailed digital model is used for generating raster templates of ISS nodes; the templates are used to detect and locate the nodes on the target image with the required accuracy. The process is performed for every frame, the resulting parameters are considered to be the orientation elements. The Kalman filter is used for statistical support of the estimation process and real time pose tracking. Finally, the modeling results presented show that the proposed method can be regarded as one means to ensure the algorithmic support of automatic space ships docking.
Directory of Open Access Journals (Sweden)
Y. B. Blokhinov
2012-07-01
Full Text Available The technical problem of creating the new Russian version of an automatic Space Cargo Ship (SCS for the International Space Station (ISS is inseparably connected to the development of a digital video system for automatically measuring the SCS position relative to ISS in the process of spacecraft docking. This paper presents a method for estimating the orientation elements based on the use of a highly detailed digital model of the ISS. The input data are digital frames from a calibrated video system and the initial values of orientation elements, these can be estimated from navigation devices or by fast-and-rough viewpoint-dependent algorithm. Then orientation elements should be defined precisely by means of algorithmic processing. The main idea is to solve the exterior orientation problem mainly on the basis of contour information of the frame image of ISS instead of ground control points. A detailed digital model is used for generating raster templates of ISS nodes; the templates are used to detect and locate the nodes on the target image with the required accuracy. The process is performed for every frame, the resulting parameters are considered to be the orientation elements. The Kalman filter is used for statistical support of the estimation process and real time pose tracking. Finally, the modeling results presented show that the proposed method can be regarded as one means to ensure the algorithmic support of automatic space ships docking.
Niemi, Antti
2013-05-01
We revisit the finite element analysis of convection-dominated flow problems within the recently developed Discontinuous Petrov-Galerkin (DPG) variational framework. We demonstrate how test function spaces that guarantee numerical stability can be computed automatically with respect to the optimal test space norm. This makes the DPG method not only stable but also robust, that is, uniformly stable with respect to the Péclet number in the current application. We employ discontinuous piecewise Bernstein polynomials as trial functions and construct a subgrid discretization that accounts for the singular perturbation character of the problem to resolve the corresponding optimal test functions. We also show that a smooth B-spline basis has certain computational advantages in the subgrid discretization. The overall effectiveness of the algorithm is demonstrated on two problems for the linear advection-diffusion equation. © 2011 Elsevier B.V.
Wang, Xueying; Li, Jun; Sheng, Weidong; An, Wei; Du, Qinfeng
2015-10-01
ABSTRACT In Space-based optical system, during the tracking for closely spaced objects (CSOs), the traditional method with a constant false alarm rate(CFAR) detecting brings either more clutter measurements or the loss of target information. CSOs can be tracked as Extended targets because their features on optical sensor's pixel-plane. A pixel partition method under the framework of Markov random field(MRF) is proposed, simulation results indicate: the method proposed provides higher pixel partition performance than traditional method, especially when the signal-noise-rate is poor.
[The combined plunger pressure-manometer method. A technique for identifying the peridural space].
Bhate, H
1992-04-01
The modified combined plunger pressure and manometer method (KSMM = Kombinierte Stempeldruck-Manometer-Methode) has proved to be a satisfactory alternative to the loss of resistance technique of Dogliotti. The method was tested for practicability and successful identification of the epidural space in 200 patients (80 of them pregnant) by physicians at different stages of their training. It makes it easy for young anaesthetists who are still in training and have not had much experience to learn to identify the epidural space. With this method the experienced operator can make an important contribution to the training of young doctors in epidural anaesthesia without fear of risks and failures.
International Nuclear Information System (INIS)
BEEBE - WANG, J.; LUCCIO, A.U.; D IMPERIO, N.; MACHIDA, S.
2002-01-01
Space charge in high intensity beams is an important issue in accelerator physics. Due to the complicity of the problems, the most effective way of investigating its effect is by computer simulations. In the resent years, many space charge simulation methods have been developed and incorporated in various 2D or 3D multi-particle-tracking codes. It has becoming necessary to benchmark these methods against each other, and against experimental results. As a part of global effort, we present our initial comparison of the space charge methods incorporated in simulation codes ORBIT++, ORBIT and SIMPSONS. In this paper, the methods included in these codes are overviewed. The simulation results are presented and compared. Finally, from this study, the advantages and disadvantages of each method are discussed
Valuing urban open space using the travel-cost method and the implications of measurement error.
Hanauer, Merlin M; Reid, John
2017-08-01
Urbanization has placed pressure on open space within and adjacent to cities. In recent decades, a greater awareness has developed to the fact that individuals derive multiple benefits from urban open space. Given the location, there is often a high opportunity cost to preserving urban open space, thus it is important for both public and private stakeholders to justify such investments. The goals of this study are twofold. First, we use detailed surveys and precise, accessible, mapping methods to demonstrate how travel-cost methods can be applied to the valuation of urban open space. Second, we assess the degree to which typical methods of estimating travel times, and thus travel costs, introduce bias to the estimates of welfare. The site we study is Taylor Mountain Regional Park, a 1100-acre space located immediately adjacent to Santa Rosa, California, which is the largest city (∼170,000 population) in Sonoma County and lies 50 miles north of San Francisco. We estimate that the average per trip access value (consumer surplus) is $13.70. We also demonstrate that typical methods of measuring travel costs significantly understate these welfare measures. Our study provides policy-relevant results and highlights the sensitivity of urban open space travel-cost studies to bias stemming from travel-cost measurement error. Copyright © 2017 Elsevier Ltd. All rights reserved.
Topics on Test Methods for Space Systems and Operations Safety: Applicability of Experimental Data
Hirsch, David B.
2009-01-01
This viewgraph presentation reviews topics on test methods for space systems and operations safety through experimentation and analysis. The contents include: 1) Perception of reality through experimentation and analysis; 2) Measurements, methods, and correlations with real life; and 3) Correlating laboratory aerospace materials flammability data with data in spacecraft environments.
Space-time discontinuous Galerkin finite element method for inviscid gas dynamics
van der Ven, H.; van der Vegt, Jacobus J.W.; Bouwman, E.G.; Bathe, K.J.
2003-01-01
In this paper an overview is given of the space-time discontinuous Galerkin finite element method for the solution of the Euler equations of gas dynamics. This technique is well suited for problems which require moving meshes to deal with changes in the domain boundary. The method is demonstrated
Variational space-time (dis)continuous Galerkin method for nonlinear free surface waves
Gagarina, Elena; van der Vegt, Jacobus J.W.; Ambati, V.R.; Bokhove, Onno
A new variational finite element method is developed for nonlinear free surface gravity water waves. This method also handles waves generated by a wave maker. Its formulation stems from Miles' variational principle for water waves together with a space-time finite element discretization that is
Two fluid space-time discontinuous Galerkin finite element method. Part II: Applications
Sollie, W.E.H.; van der Vegt, Jacobus J.W.
2009-01-01
The numerical method for two fluid flow computations presented in Sollie, Bokhove \\& van der Vegt, Two Fluid Space-Time Discontinuous Galerkin Finite Element Method. Part I: Numerical Algorithm is applied to a number of one and two dimensional single and two fluid test problems, including a magma -
Fabrication of Metallic Biomedical Scaffolds with the Space Holder Method: A Review.
Arifvianto, Budi; Zhou, Jie
2014-05-06
Bone tissue engineering has been increasingly studied as an alternative approach to bone defect reconstruction. In this approach, new bone cells are stimulated to grow and heal the defect with the aid of a scaffold that serves as a medium for bone cell formation and growth. Scaffolds made of metallic materials have preferably been chosen for bone tissue engineering applications where load-bearing capacities are required, considering the superior mechanical properties possessed by this type of materials to those of polymeric and ceramic materials. The space holder method has been recognized as one of the viable methods for the fabrication of metallic biomedical scaffolds. In this method, temporary powder particles, namely space holder, are devised as a pore former for scaffolds. In general, the whole scaffold fabrication process with the space holder method can be divided into four main steps: (i) mixing of metal matrix powder and space-holding particles; (ii) compaction of granular materials; (iii) removal of space-holding particles; (iv) sintering of porous scaffold preform. In this review, detailed procedures in each of these steps are presented. Technical challenges encountered during scaffold fabrication with this specific method are addressed. In conclusion, strategies are yet to be developed to address problematic issues raised, such as powder segregation, pore inhomogeneity, distortion of pore sizes and shape, uncontrolled shrinkage and contamination.
McLinko, Ryan M.; Sagar, Basant V.
2009-12-01
Space-based solar power (SSP) generation is being touted as a solution to our ever-increasing energy consumption and dependence on fossil fuels. Satellites in Earth's orbit can capture solar energy through photovoltaic cells and transmit that power to ground based stations. Solar cells in orbit are not hindered by weather, clouds, or night. The energy generated by this process is clean and pollution-free. Although the concept of space-based solar power was initially proposed nearly 40 years ago, the level of technology in photovoltaics, power transmission, materials, and efficient satellite design has finally reached a level of maturity that makes solar power from space a feasible prospect. Furthermore, new strategies in methods for solar energy acquisition and transmission can lead to simplifications in design, reductions in cost and reduced risk. This paper proposes using a distributed array of small satellites to collect power from the Sun, as compared to the more traditional SSP design that consists of one monolithic satellite. This concept mitigates some of SSP's most troublesome historic constraints, such as the requirement for heavy lift launch vehicles and the need for significant assembly in space. Instead, a larger number of smaller satellites designed to collect solar energy are launched independently. A high frequency beam will be used to aggregate collected power into a series of transmission antennas, which beam the energy to Earth's surface at a lower frequency. Due to the smaller power expectations of each satellite and the relatively short distance of travel from low earth orbit, such satellites can be designed with smaller arrays. The inter-satellite rectenna devices can also be smaller and lighter in weight. Our paper suggests how SSP satellites can be designed small enough to fit within ESPA standards and therefore use rideshare to achieve orbit. Alternatively, larger versions could be launched on Falcon 9s or on Falcon 1s with booster stages
Landweber-Kaczmarz method in Banach spaces with inexact inner solvers
Jin, Qinian
2016-10-01
In recent years the Landweber-Kaczmarz method has been proposed for solving nonlinear ill-posed inverse problems in Banach spaces using general convex penalty functions. The implementation of this method involves solving a (nonsmooth) convex minimization problem at each iteration step and the existing theory requires its exact resolution which in general is impossible in practical applications. In this paper we propose a version of the Landweber-Kaczmarz method in Banach spaces in which the minimization problem involved in each iteration step is solved inexactly. Based on the \\varepsilon -subdifferential calculus we give a convergence analysis of our method. Furthermore, using Nesterov's strategy, we propose a possible accelerated version of the Landweber-Kaczmarz method. Numerical results on computed tomography and parameter identification in partial differential equations are provided to support our theoretical results and to demonstrate our accelerated method.
Methods of body orientation in space in the absence of support under weightless conditions
Yeremin, A. V.; Stepantsov, V. I.; Chekidra, I. F.; Borisenko, I. P.; Kolosov, I. A.
1975-01-01
The experience accumulated in training subjects in methods of body orientation in space indicates the necessity of clear planning of the training process. After theoretical familiarization with the principles of body orientation in space and reviewing training films, practical mastery of the body orientation methods begins with working out of the individual elements on the Zhukovskiy stool. Then, the correctness and sequence of movements are carefully mastered in water, and the motor skills are then reinforced under time deficit conditions, on the vaulting bars, trampolines, and, in the concluding stage of training, the methods of orienting the body in space in weightlessness are worked out in laboratory-aircraft, with and without the spacesuit and with and without a load.
A randomized clinical trial to compare three methods of orthodontic space closure.
Dixon, V; Read, M J F; O'Brien, K D; Worthington, H V; Mandall, N A
2002-03-01
To compare the rates of orthodontic space closure for: Active ligatures, polyurethane powerchain (Rocky Mountain Orthodontics, RMO Europe, Parc d'Innovation, Rue Geiler de Kaysersberg, 67400 Illkirch-Graffenstaden, Strasbourg, France) and nickel titanium springs. Patients entering the space closure phase of fixed orthodontic treatment attending six orthodontic providers. Twelve patients received active ligatures (48 quadrants), 10 patients received powerchain (40 quadrants) and 11 patients, nickel-titanium springs (44 quadrants). Patients were randomly allocated for treatment with active ligatures, powerchain or nickel titanium springs. Upper and lower study models were collected at the start of space closure (T(o)) and 4 months later (T(1)). We recorded whether the patient wore Class II or Class III elastics. Space present in all four quadrants was measured, by a calibrated examiner, using Vernier callipers at T(o) and T(1.) The rate of space closure, in millimetres per month (4 weeks) and a 4-monthly rate, was then calculated. Examiner reliability was assessed at least 2 weeks later. Mean rates of space closure were 0.35 mm/month for active ligatures, 0.58 mm/month for powerchain, and 0.81 mm/month for NiTi springs. No statistically significant differences were found between any methods with the exception of NiTi springs showing more rapid space closure than active ligatures (P space closure. NiTi springs gave the most rapid rate of space closure and may be considered the treatment of choice. However, powerchain provides a cheaper treatment option that is as effective. The use of inter-arch elastics does not appear to influence rate of space closure.
The application of the phase space time evolution method to electron shielding
Cordaro, M. C.; Zucker, M. S.
1972-01-01
A computer technique for treating the motion of charged and neutral particles and called the phase space time evolution method was developed. This technique employs the computer's bookkeeping capacity to keep track of the time development of a phase space distribution of particles. This method was applied to a study of the penetration of electrons. A 1 MeV beam of electrons normally incident on a semi-infinite slab of aluminum was used. Results of the calculation were compared with Monte Carlo calculations and experimental results. Time-dependent PSTE electron penetration results for the same problem are presented.
A domain decomposition method for analyzing a coupling between multiple acoustical spaces (L).
Chen, Yuehua; Jin, Guoyong; Liu, Zhigang
2017-05-01
This letter presents a domain decomposition method to predict the acoustic characteristics of an arbitrary enclosure made up of any number of sub-spaces. While the Lagrange multiplier technique usually has good performance for conditional extremum problems, the present method avoids involving extra coupling parameters and theoretically ensures the continuity conditions of both sound pressure and particle velocity at the coupling interface. Comparisons with the finite element results illustrate the accuracy and efficiency of the present predictions and the effect of coupling parameters between sub-spaces on the natural frequencies and mode shapes of the overall enclosure is revealed.
Modeling and Simulation of DC Power Electronics Systems Using Harmonic State Space (HSS) Method
DEFF Research Database (Denmark)
Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth
2015-01-01
based on the state-space averaging and generalized averaging, these also have limitations to show the same results as with the non-linear time domain simulations. This paper presents a modeling and simulation method for a large dc power electronic system by using Harmonic State Space (HSS) modeling....... Through this method, the required computation time and CPU memory for large dc power electronics systems can be reduced. Besides, the achieved results show the same results as with the non-linear time domain simulation, but with the faster simulation time which is beneficial in a large network....
Directory of Open Access Journals (Sweden)
Panfeng Huang
2014-09-01
Full Text Available The tethered space robot (TSR is a new concept of space robot which consists of a robot platform, space tether and operation robot. This paper presents a multi-objective optimal trajectory planning and a coordinated tracking control scheme for TSR based on velocity impulse in the approaching phase. Both total velocity impulse and flight time are included in this optimization. The non-dominated sorting genetic algorithm is employed to obtain the optimal trajectory Pareto solution using the TSR dynamic model and optimal trajectory planning model. The coordinated tracking control scheme utilizes optimal velocity impulse. Furthermore, the PID controller is designed in order to compensate for the distance measurement errors. The PID control force is optimized and distributed to thrusters and the space tether using a simulated annealing algorithm. The attitude interferential torque of the space tether is compensated a using time-delay algorithm through reaction wheels. The simulation results show that the multi-objective optimal trajectory planning method can reveal the relationships among flight time, fuel consumption, planar view angle and velocity impulse number. This method can provide a series of optimal trajectory according to a number of special tasks. The coordinated control scheme can significantly save thruster fuel for tracking the optimal trajectory, restrain the attitude interferential torque produced by space tether and maintain the relative attitude stability of the operation robot.
Some Results of Fixed Points in Generalized Metric Space by Methods of Suzuki and Samet
Directory of Open Access Journals (Sweden)
Hojjat Afshari
2015-08-01
Full Text Available In 1992 Dhage introduced the notion of generalized metric or D-metric spaces and claimed that D-metric convergence define a Hausdorff topology and that $D$-metric is sequentially continuous in all the three variables. Many authors have taken these claims for granted and used them in proving fixed point theorems in $D$-metric spaces. In 1996 Rhoades generalized Dhages contractive condition by increasing the number of factors and proved the existence of unique fixed point of a self map in $D$-metric space. Recently motivated by the concept of compatibility for metric space. In 2002 Sing and Sharma introduced the concept of $D$-compatibility of maps in $D$-metric space and proved some fixed point theorems using a contractive condition. In this paper ,we prove some fixed point theorems and common fixed point theorems in $D^*$-complete metric spaces under particular conditions among weak compatibility. Also by Using method of Suzuki and Samet we prove some theorems in generalised metric spaces.
Markov chain Monte Carlo methods for state-space models with point process observations.
Yuan, Ke; Girolami, Mark; Niranjan, Mahesan
2012-06-01
This letter considers how a number of modern Markov chain Monte Carlo (MCMC) methods can be applied for parameter estimation and inference in state-space models with point process observations. We quantified the efficiencies of these MCMC methods on synthetic data, and our results suggest that the Reimannian manifold Hamiltonian Monte Carlo method offers the best performance. We further compared such a method with a previously tested variational Bayes method on two experimental data sets. Results indicate similar performance on the large data sets and superior performance on small ones. The work offers an extensive suite of MCMC algorithms evaluated on an important class of models for physiological signal analysis.
Frames and other bases in abstract and function spaces novel methods in harmonic analysis
Gia, Quoc; Mayeli, Azita; Mhaskar, Hrushikesh; Zhou, Ding-Xuan
2017-01-01
The first of a two volume set on novel methods in harmonic analysis, this book draws on a number of original research and survey papers from well-known specialists detailing the latest innovations and recently discovered links between various fields. Along with many deep theoretical results, these volumes contain numerous applications to problems in signal processing, medical imaging, geodesy, statistics, and data science. The chapters within cover an impressive range of ideas from both traditional and modern harmonic analysis, such as: the Fourier transform, Shannon sampling, frames, wavelets, functions on Euclidean spaces, analysis on function spaces of Riemannian and sub-Riemannian manifolds, Fourier analysis on manifolds and Lie groups, analysis on combinatorial graphs, sheaves, co-sheaves, and persistent homologies on topological spaces. Volume I is organized around the theme of frames and other bases in abstract and function spaces, covering topics such as: The advanced development of frames, including ...
Method of locating related items in a geometric space for data mining
Hendrickson, Bruce A.
1999-01-01
A method for locating related items in a geometric space transforms relationships among items to geometric locations. The method locates items in the geometric space so that the distance between items corresponds to the degree of relatedness. The method facilitates communication of the structure of the relationships among the items. The method is especially beneficial for communicating databases with many items, and with non-regular relationship patterns. Examples of such databases include databases containing items such as scientific papers or patents, related by citations or keywords. A computer system adapted for practice of the present invention can include a processor, a storage subsystem, a display device, and computer software to direct the location and display of the entities. The method comprises assigning numeric values as a measure of similarity between each pairing of items. A matrix is constructed, based on the numeric values. The eigenvectors and eigenvalues of the matrix are determined. Each item is located in the geometric space at coordinates determined from the eigenvectors and eigenvalues. Proper construction of the matrix and proper determination of coordinates from eigenvectors can ensure that distance between items in the geometric space is representative of the numeric value measure of the items' similarity.
Protein space: a natural method for realizing the nature of protein universe.
Yu, Chenglong; Deng, Mo; Cheng, Shiu-Yuen; Yau, Shek-Chung; He, Rong L; Yau, Stephen S-T
2013-02-07
Current methods cannot tell us what the nature of the protein universe is concretely. They are based on different models of amino acid substitution and multiple sequence alignment which is an NP-hard problem and requires manual intervention. Protein structural analysis also gives a direction for mapping the protein universe. Unfortunately, now only a minuscule fraction of proteins' 3-dimensional structures are known. Furthermore, the phylogenetic tree representations are not unique for any existing tree construction methods. Here we develop a novel method to realize the nature of protein universe. We show the protein universe can be realized as a protein space in 60-dimensional Euclidean space using a distance based on a normalized distribution of amino acids. Every protein is in one-to-one correspondence with a point in protein space, where proteins with similar properties stay close together. Thus the distance between two points in protein space represents the biological distance of the corresponding two proteins. We also propose a natural graphical representation for inferring phylogenies. The representation is natural and unique based on the biological distances of proteins in protein space. This will solve the fundamental question of how proteins are distributed in the protein universe. Copyright © 2012 Elsevier Ltd. All rights reserved.
Fast polarimetric dehazing method for visibility enhancement in HSI colour space
Zhang, Wenfei; Liang, Jian; Ren, Liyong; Ju, Haijuan; Bai, Zhaofeng; Wu, Zhaoxin
2017-09-01
Image haze removal has attracted much attention in optics and computer vision fields in recent years due to its wide applications. In particular, the fast and real-time dehazing methods are of significance. In this paper, we propose a fast dehazing method in hue, saturation and intensity colour space based on the polarimetric imaging technique. We implement the polarimetric dehazing method in the intensity channel, and the colour distortion of the image is corrected using the white patch retinex method. This method not only reserves the detailed information restoration capacity, but also improves the efficiency of the polarimetric dehazing method. Comparison studies with state of the art methods demonstrate that the proposed method obtains equal or better quality results and moreover the implementation is much faster. The proposed method is promising in real-time image haze removal and video haze removal applications.
Geometric shapes inversion method of space targets by ISAR image segmentation
Huo, Chao-ying; Xing, Xiao-yu; Yin, Hong-cheng; Li, Chen-guang; Zeng, Xiang-yun; Xu, Gao-gui
2017-11-01
The geometric shape of target is an effective characteristic in the process of space targets recognition. This paper proposed a method of shape inversion of space target based on components segmentation from ISAR image. The Radon transformation, Hough transformation, K-means clustering, triangulation will be introduced into ISAR image processing. Firstly, we use Radon transformation and edge detection to extract space target's main body spindle and solar panel spindle from ISAR image. Then the targets' main body, solar panel, rectangular and circular antenna are segmented from ISAR image based on image detection theory. Finally, the sizes of every structural component are computed. The effectiveness of this method is verified using typical targets' simulation data.
A method simulating random magnetic field in interplanetary space by an autoregressive method
International Nuclear Information System (INIS)
Kato, Masahito; Sakai, Takasuke
1985-01-01
With an autoregressive method, we tried to generate the random noise fitting in with the power spectrum which can be analytically Fouriertransformed into an autocorrelation function. Although we can not directly compare our method with FFT by Owens (1978), we can only point out the following; FFT method should determine at first the number of data points N, or the total length to be generated and we cannot generate random data more than N. Because, beyond the NΔy, the generated data repeats the same pattern as below NΔy, where Δy = minimum interval for random noise. So if you want to change or increase N after generating the random noise, you should start the generation from the first step. The characteristic of the generated random number may depend upon the number of N, judging from the generating method. Once the prediction error filters are determined, our method can produce successively the random numbers, that is, we can possibly extend N to infinite without any effort. (author)
A BHR Composite Network-Based Visualization Method for Deformation Risk Level of Underground Space.
Directory of Open Access Journals (Sweden)
Wei Zheng
Full Text Available This study proposes a visualization processing method for the deformation risk level of underground space. The proposed method is based on a BP-Hopfield-RGB (BHR composite network. Complex environmental factors are integrated in the BP neural network. Dynamic monitoring data are then automatically classified in the Hopfield network. The deformation risk level is combined with the RGB color space model and is displayed visually in real time, after which experiments are conducted with the use of an ultrasonic omnidirectional sensor device for structural deformation monitoring. The proposed method is also compared with some typical methods using a benchmark dataset. Results show that the BHR composite network visualizes the deformation monitoring process in real time and can dynamically indicate dangerous zones.
A Novel Line Space Voting Method for Vanishing-Point Detection of General Road Images
Directory of Open Access Journals (Sweden)
Zongsheng Wu
2016-06-01
Full Text Available Vanishing-point detection is an important component for the visual navigation system of an autonomous mobile robot. In this paper, we present a novel line space voting method for fast vanishing-point detection. First, the line segments are detected from the road image by the line segment detector (LSD method according to the pixel’s gradient and texture orientation computed by the Sobel operator. Then, the vanishing-point of the road is voted on by considering the points of the lines and their neighborhood spaces with weighting methods. Our algorithm is simple, fast, and easy to implement with high accuracy. It has been experimentally tested with over hundreds of structured and unstructured road images. The experimental results indicate that the proposed method is effective and can meet the real-time requirements of navigation for autonomous mobile robots and unmanned ground vehicles.
A Novel Line Space Voting Method for Vanishing-Point Detection of General Road Images.
Wu, Zongsheng; Fu, Weiping; Xue, Ru; Wang, Wen
2016-06-23
Vanishing-point detection is an important component for the visual navigation system of an autonomous mobile robot. In this paper, we present a novel line space voting method for fast vanishing-point detection. First, the line segments are detected from the road image by the line segment detector (LSD) method according to the pixel's gradient and texture orientation computed by the Sobel operator. Then, the vanishing-point of the road is voted on by considering the points of the lines and their neighborhood spaces with weighting methods. Our algorithm is simple, fast, and easy to implement with high accuracy. It has been experimentally tested with over hundreds of structured and unstructured road images. The experimental results indicate that the proposed method is effective and can meet the real-time requirements of navigation for autonomous mobile robots and unmanned ground vehicles.
Real-space grid implementation of the projector augmented wave method
DEFF Research Database (Denmark)
Mortensen, Jens Jørgen; Hansen, Lars Bruno; Jacobsen, Karsten Wedel
2005-01-01
, and potentials allows for flexible boundary conditions, efficient multigrid algorithms for solving Poisson and Kohn-Sham equations, and efficient parallelization using simple real-space domain-decomposition. We use the PAW method to perform all-electron calculations in the frozen core approximation, with smooth...
Reconstruction of electron beam distribution in phase space by using parallel maximum entropy method
International Nuclear Information System (INIS)
Hajima, R.; Hirotsu, T.; Kondo, S.
1997-01-01
Reconstruction of electron beam distribution in six-dimensional phase space by tomographic approach is presented. Maximum entropy method (MENT) is applied to the reconstruction and compared with filtered back-projection. Finally, MENT is adapted to parallel computing environment with PVM. (orig.)
A new method of spatial analysis of irregularly spaced HLB data and biological implications
Field data on intensity of plant diseases is very often irregularly spaced (i.e., there are varying amounts of distance between rows, ponds, voids, roads, houses, or other land areas). A new method of analysis, sometimes called second-generation wavelet analysis, can be used on this type of irregula...
DEFF Research Database (Denmark)
Chen, Jingzhe; Thygesen, Kristian S.; Jacobsen, Karsten W.
2012-01-01
over k points and real space makes the code highly efficient and applicable to systems containing several hundreds of atoms. The method is applied to a number of different systems, demonstrating the effects of bias and gate voltages, multiterminal setups, nonequilibrium forces, and spin transport....
Energy Technology Data Exchange (ETDEWEB)
Mezzacappa, Anthony [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Endeve, Eirik [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hauck, Cory D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Xing, Yulong [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2015-02-01
We extend the positivity-preserving method of Zhang & Shu [49] to simulate the advection of neutral particles in phase space using curvilinear coordinates. The ability to utilize these coordinates is important for non-equilibrium transport problems in general relativity and also in science and engineering applications with specific geometries. The method achieves high-order accuracy using Discontinuous Galerkin (DG) discretization of phase space and strong stabilitypreserving, Runge-Kutta (SSP-RK) time integration. Special care in taken to ensure that the method preserves strict bounds for the phase space distribution function f; i.e., f ϵ [0, 1]. The combination of suitable CFL conditions and the use of the high-order limiter proposed in [49] is su cient to ensure positivity of the distribution function. However, to ensure that the distribution function satisfies the upper bound, the discretization must, in addition, preserve the divergencefree property of the phase space ow. Proofs that highlight the necessary conditions are presented for general curvilinear coordinates, and the details of these conditions are worked out for some commonly used coordinate systems (i.e., spherical polar spatial coordinates in spherical symmetry and cylindrical spatial coordinates in axial symmetry, both with spherical momentum coordinates). Results from numerical experiments - including one example in spherical symmetry adopting the Schwarzschild metric - demonstrate that the method achieves high-order accuracy and that the distribution function satisfies the maximum principle.
Analysis of Surface Waves in Saturated Layered Poroelastic Half-Spaces Using the Thin Layer Method
Chai, Huayou; Cui, Yujun; Zhang, Dianji
2018-03-01
There are multiple modes of surface waves in saturated layered poroelastic half-spaces. The phase velocity and the attenuation of the modes are frequency dependent. The frequency behaviour of the modes can be studied using the layer transfer, stiffness and the transmission/reflection matrix methods. However, it is very difficult to find the complex roots of the determinants because the entries of the matrices involve the complex exponential functions of the wavenumber and the thickness of layer. To overcome this difficulty, the entries in the matrix are expressed in the form of algebraic functions using the thin layer method. Thus, the eigenvalues and eigenvectors can be easily solved using the matrix decomposition techniques instead of the root-searching ones. Some of the eigenvalues correspond to the wavenumbers of the surface waves, and can be picked out based on the characteristics of the surface waves. The frequency behaviour, variations of the pore pressure and the skeleton's displacements with the depth can be then investigated from the corresponding eigenvalues and eigenvectors, respectively. The method is verified by comparing the analytical and the discrete results in the saturated poroelastic half-space with the permeable surface. The method is applied to appreciate the effects of an impermeable surface on Rayleigh waves (R-waves) and the existence of Stoneley waves in the poroelastic half-space. The frequency behaviour of Rayleigh waves in three typical layered poroelastic half-spaces is also analyzed.
The foam drainage equation with time- and space-fractional derivatives solved by the Adomian method
Directory of Open Access Journals (Sweden)
Zoubir Dahmani
2008-10-01
Full Text Available In this paper, by introducing the fractional derivative in the sense of Caputo, we apply the Adomian decomposition method for the foam drainage equation with time- and space-fractional derivative. As a result, numerical solutions are obtained in a form of rapidly convergent series with easily computable components.
Review of the different methods to derive average spacing from resolved resonance parameters sets
International Nuclear Information System (INIS)
Fort, E.; Derrien, H.; Lafond, D.
1979-12-01
The average spacing of resonances is an important parameter for statistical model calculations, especially concerning non fissile nuclei. The different methods to derive this average value from resonance parameters sets have been reviewed and analyzed in order to tentatively detect their respective weaknesses and propose recommendations. Possible improvements are suggested
The General Iterative Methods for Asymptotically Nonexpansive Semigroups in Banach Spaces
Directory of Open Access Journals (Sweden)
Rabian Wangkeeree
2012-01-01
Full Text Available We introduce the general iterative methods for finding a common fixed point of asymptotically nonexpansive semigroups which is a unique solution of some variational inequalities. We prove the strong convergence theorems of such iterative scheme in a reflexive Banach space which admits a weakly continuous duality mapping. The main result extends various results existing in the current literature.
Preconditioned iterative methods for space-time fractional advection-diffusion equations
Zhao, Zhi; Jin, Xiao-Qing; Lin, Matthew M.
2016-08-01
In this paper, we propose practical numerical methods for solving a class of initial-boundary value problems of space-time fractional advection-diffusion equations. First, we propose an implicit method based on two-sided Grünwald formulae and discuss its stability and consistency. Then, we develop the preconditioned generalized minimal residual (preconditioned GMRES) method and preconditioned conjugate gradient normal residual (preconditioned CGNR) method with easily constructed preconditioners. Importantly, because resulting systems are Toeplitz-like, fast Fourier transform can be applied to significantly reduce the computational cost. We perform numerical experiments to demonstrate the efficiency of our preconditioners, even in cases with variable coefficients.
A Microwave Free-Space Method Using Artificial Lens with Anti-reflection Layer
Zhang, Yangjun; Aratani, Yuki; Nakazima, Hironari
2017-12-01
This paper describes a microwave free-space method using flat artificial lens antennas with anti-reflection layer. The lens antenna is made of an artificial material of metal particle. Comparing with our previous study, Anti-reflection (AR) layers are supplemented to the lens in this study to obtain a wave matching on the air-lens interface. The improved lens is in a disk shape of 50 mm diameter and 5.9 mm thickness. The lens is applied in a free-space setup, in which it is set in front of a patch antenna resonating at 15 GHz to get a high gain. The free-space setup is used to measure microwave attenuation and phase shift through a sawdust sample. The experimental results show that the multiple-reflection in the free-space method becomes small, because the reflection on air-lens interface has been reduced. The proposed AR lens antenna is flat and very small in the size. It is possible to construct a very compact and low cost free-space setup using the improved lens.
Convergence rates for the iteratively regularized Gauss–Newton method in Banach spaces
International Nuclear Information System (INIS)
Kaltenbacher, Barbara; Hofmann, Bernd
2010-01-01
In this paper we consider the iteratively regularized Gauss–Newton method (IRGNM) in a Banach space setting and prove optimal convergence rates under approximate source conditions. These are related to the classical concept of source conditions that is available only in Hilbert space. We provide results in the framework of general index functions, which include, e.g. Hölder and logarithmic rates. Concerning the regularization parameters in each Newton step as well as the stopping index, we provide both a priori and a posteriori strategies, the latter being based on the discrepancy principle
Optical method for mapping the transverse phase space of a charged particle beam
International Nuclear Information System (INIS)
Fiorito, R.B.; Shkvarunets, A.G.; O'Shea, P.G.
2002-01-01
We are developing an all optical method to map the transverse phase space map of a charged particle beam. Our technique employs OTR interferometry (OTRI) in combination with a scanning pinhole to make local orthogonal (x,y) divergence and trajectory angle measurements as function of position within the transverse profile of the beam. The localized data allows a reconstruction of the horizontal and vertical phase spaces of the beam. We have also demonstrated how single and multiple pinholes can in principle be used to make such measurements simultaneously
A Fully Discrete Galerkin Method for a Nonlinear Space-Fractional Diffusion Equation
Directory of Open Access Journals (Sweden)
Yunying Zheng
2011-01-01
Full Text Available The spatial transport process in fractal media is generally anomalous. The space-fractional advection-diffusion equation can be used to characterize such a process. In this paper, a fully discrete scheme is given for a type of nonlinear space-fractional anomalous advection-diffusion equation. In the spatial direction, we use the finite element method, and in the temporal direction, we use the modified Crank-Nicolson approximation. Here the fractional derivative indicates the Caputo derivative. The error estimate for the fully discrete scheme is derived. And the numerical examples are also included which are in line with the theoretical analysis.
Populating the Mix Space: Parametric Methods for Generating Multitrack Audio Mixtures
Directory of Open Access Journals (Sweden)
Alex Wilson
2017-12-01
Full Text Available The creation of multitrack mixes by audio engineers is a time-consuming activity and creating high-quality mixes requires a great deal of knowledge and experience. Previous studies on the perception of music mixes have been limited by the relatively small number of human-made mixes analysed. This paper describes a novel “mix-space”, a parameter space which contains all possible mixes using a finite set of tools, as well as methods for the parametric generation of artificial mixes in this space. Mixes that use track gain, panning and equalisation are considered. This allows statistical methods to be used in the study of music mixing practice, such as Monte Carlo simulations or population-based optimisation methods. Two applications are described: an investigation into the robustness and accuracy of tempo-estimation algorithms and an experiment to estimate distributions of spectral centroid values within sets of mixes. The potential for further work is also described.
An Encoding Method for Compressing Geographical Coordinates in 3d Space
Qian, C.; Jiang, R.; Li, M.
2017-09-01
This paper proposed an encoding method for compressing geographical coordinates in 3D space. By the way of reducing the length of geographical coordinates, it helps to lessen the storage size of geometry information. In addition, the encoding algorithm subdivides the whole space according to octree rules, which enables progressive transmission and loading. Three main steps are included in this method: (1) subdividing the whole 3D geographic space based on octree structure, (2) resampling all the vertices in 3D models, (3) encoding the coordinates of vertices with a combination of Cube Index Code (CIC) and Geometry Code. A series of geographical 3D models were applied to evaluate the encoding method. The results showed that this method reduced the storage size of most test data by 90 % or even more under the condition of a speed of encoding and decoding. In conclusion, this method achieved a remarkable compression rate in vertex bit size with a steerable precision loss. It shall be of positive meaning to the web 3d map storing and transmission.
Colombo, Oscar L. (Editor)
1992-01-01
This symposium on space and airborne techniques for measuring gravity fields, and related theory, contains papers on gravity modeling of Mars and Venus at NASA/GSFC, an integrated laser Doppler method for measuring planetary gravity fields, observed temporal variations in the earth's gravity field from 16-year Starlette orbit analysis, high-resolution gravity models combining terrestrial and satellite data, the effect of water vapor corrections for satellite altimeter measurements of the geoid, and laboratory demonstrations of superconducting gravity and inertial sensors for space and airborne gravity measurements. Other papers are on airborne gravity measurements over the Kelvin Seamount; the accuracy of GPS-derived acceleration from moving platform tests; airborne gravimetry, altimetry, and GPS navigation errors; controlling common mode stabilization errors in airborne gravity gradiometry, GPS/INS gravity measurements in space and on a balloon, and Walsh-Fourier series expansion of the earth's gravitational potential.
Directory of Open Access Journals (Sweden)
Fengqian Dou
2016-01-01
Full Text Available This paper proposes a novel relative navigation control strategy based on the relation space method (RSM for articulated underground trackless vehicles. In the RSM, a self-organizing, competitive neural network is used to identify the space around the vehicle, and the spatial geometric relationships of the identified space are used to determine the vehicle’s optimal driving direction. For driving control, the trajectories of the articulated vehicles are analyzed, and data-based steering and speed control modules are developed to reduce modeling complexity. Simulation shows that the proposed RSM can choose the correct directions for articulated vehicles in different tunnels. The effectiveness and feasibility of the resulting novel relative navigation control strategy are validated through experiments.
Scale Space Methods for Analysis of Type 2 Diabetes Patients' Blood Glucose Values
Directory of Open Access Journals (Sweden)
Stein Olav Skrøvseth
2011-01-01
Full Text Available We describe how scale space methods can be used for quantitative analysis of blood glucose concentrations from type 2 diabetes patients. Blood glucose values were recorded voluntarily by the patients over one full year as part of a self-management process, where the time and frequency of the recordings are decided by the patients. This makes a unique dataset in its extent, though with a large variation in reliability of the recordings. Scale space and frequency space techniques are suited to reveal important features of unevenly sampled data, and useful for identifying medically relevant features for use both by patients as part of their self-management process, and provide useful information for physicians.
A Novel Transfer Learning Method Based on Common Space Mapping and Weighted Domain Matching
Liang, Ru-Ze
2017-01-17
In this paper, we propose a novel learning framework for the problem of domain transfer learning. We map the data of two domains to one single common space, and learn a classifier in this common space. Then we adapt the common classifier to the two domains by adding two adaptive functions to it respectively. In the common space, the target domain data points are weighted and matched to the target domain in term of distributions. The weighting terms of source domain data points and the target domain classification responses are also regularized by the local reconstruction coefficients. The novel transfer learning framework is evaluated over some benchmark cross-domain data sets, and it outperforms the existing state-of-the-art transfer learning methods.
Applications of asynoptic space - Time Fourier transform methods to scanning satellite measurements
Lait, Leslie R.; Stanford, John L.
1988-01-01
A method proposed by Salby (1982) for computing the zonal space-time Fourier transform of asynoptically acquired satellite data is discussed. The method and its relationship to other techniques are briefly described, and possible problems in applying it to real data are outlined. Examples of results obtained using this technique are given which demonstrate its sensitivity to small-amplitude signals. A number of waves are found which have previously been observed as well as two not heretofore reported. A possible extension of the method which could increase temporal and longitudinal resolution is described.
A Novel Method Describing the Space Charge Limited Region in a Planar Diode
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Mitra Ghergherehchi
2017-11-01
Full Text Available A novel and rather simple method is presented to describe the physics of space-charge region in a planar diode. The method deals with the issue in the time domain and as a consequence transient time behavior can be achieved. Potential distributions and currents obtained using this technique, supposing zero initial velocity for electrons, reveal absolute agreement with Child's results. Moreover, applying the method for non-zero uniform initial velocity for electrons, gives results which are in good agreement with previous works
Directory of Open Access Journals (Sweden)
Sedigheh Farzaneh Javan
2017-01-01
Full Text Available A new approach based on the Reproducing Kernel Hilbert Space Method is proposed to approximate the solution of the second-kind nonlinear integral equations. In this case, the Gram-Schmidt process is substituted by another process so that a satisfactory result is obtained. In this method, the solution is expressed in the form of a series. Furthermore, the convergence of the proposed technique is proved. In order to illustrate the effectiveness and efficiency of the method, four sample integral equations arising in electromagnetics are solved via the given algorithm.
Guidance methods in psychological «spaces» of self-determination
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Nikolai S. Prjazhnikov
2017-09-01
Full Text Available Self-determination is deemed as search and continuous refinement of the meaning of the future life. The paper discusses various options for self-determination, i.e. professional, personal, social, and other ones. Self-determination means making a certain choice. This may be career choice («career self-determination», choice of a moral position («personal self-determination», choice of one’s position in society associated with image and style of life, status in various social groups («social self-determination», choice of options («Leisure selfdetermination», or even choice of relationship type («family self-determination», etc. The generalized options and methods of orientation in various «space» of self-determination are highlighted. The psychological «spaces» are regarded as a metaphor that reflects and arranges a certain field of search for the meanings of self-determination. Each «space» is constructed according to a certain principle based on certain criteria. Psychological «space» may be determined as diverse, and in this set of self-determining personality one must be able to navigate. There are main groups of psychological «space» including the typology of options for planning life and career, the typology of work activity, the typology of professions. It is important for self-determination to define the future professional activity. Various methods are presented that allow a person to get a career orientation in complex «space» of career and life choices. Particular attention is paid to self-determination of children in adolescence. Various modern approaches in career guidance and P.Ya. Galperin’s career «orientation» principles are drawn to a concordance.
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Xingchu Gong
Full Text Available A design space approach was applied to optimize the extraction process of Danhong injection. Dry matter yield and the yields of five active ingredients were selected as process critical quality attributes (CQAs. Extraction number, extraction time, and the mass ratio of water and material (W/M ratio were selected as critical process parameters (CPPs. Quadratic models between CPPs and CQAs were developed with determination coefficients higher than 0.94. Active ingredient yields and dry matter yield increased as the extraction number increased. Monte-Carlo simulation with models established using a stepwise regression method was applied to calculate the probability-based design space. Step length showed little effect on the calculation results. Higher simulation number led to results with lower dispersion. Data generated in a Monte Carlo simulation following a normal distribution led to a design space with a smaller size. An optimized calculation condition was obtained with 10,000 simulation times, 0.01 calculation step length, a significance level value of 0.35 for adding or removing terms in a stepwise regression, and a normal distribution for data generation. The design space with a probability higher than 0.95 to attain the CQA criteria was calculated and verified successfully. Normal operating ranges of 8.2-10 g/g of W/M ratio, 1.25-1.63 h of extraction time, and two extractions were recommended. The optimized calculation conditions can conveniently be used in design space development for other pharmaceutical processes.
Application of hierarchical clustering method to classify of space-time rainfall patterns
Yu, Hwa-Lung; Chang, Tu-Je
2010-05-01
Understanding the local precipitation patterns is essential to the water resources management and flooding mitigation. The precipitation patterns can vary in space and time depending upon the factors from different spatial scales such as local topological changes and macroscopic atmospheric circulation. The spatiotemporal variation of precipitation in Taiwan is significant due to its complex terrain and its location at west pacific and subtropical area, where is the boundary between the pacific ocean and Asia continent with the complex interactions among the climatic processes. This study characterizes local-scale precipitation patterns by classifying the historical space-time precipitation records. We applied the hierarchical ascending clustering method to analyze the precipitation records from 1960 to 2008 at the six rainfall stations located in Lan-yang catchment at the northeast of the island. Our results identify the four primary space-time precipitation types which may result from distinct driving forces from the changes of atmospheric variables and topology at different space-time scales. This study also presents an important application of the statistical downscaling to combine large-scale upper-air circulation with local space-time precipitation patterns.
Gong, Xingchu; Li, Yao; Chen, Huali; Qu, Haibin
2015-01-01
A design space approach was applied to optimize the extraction process of Danhong injection. Dry matter yield and the yields of five active ingredients were selected as process critical quality attributes (CQAs). Extraction number, extraction time, and the mass ratio of water and material (W/M ratio) were selected as critical process parameters (CPPs). Quadratic models between CPPs and CQAs were developed with determination coefficients higher than 0.94. Active ingredient yields and dry matter yield increased as the extraction number increased. Monte-Carlo simulation with models established using a stepwise regression method was applied to calculate the probability-based design space. Step length showed little effect on the calculation results. Higher simulation number led to results with lower dispersion. Data generated in a Monte Carlo simulation following a normal distribution led to a design space with a smaller size. An optimized calculation condition was obtained with 10,000 simulation times, 0.01 calculation step length, a significance level value of 0.35 for adding or removing terms in a stepwise regression, and a normal distribution for data generation. The design space with a probability higher than 0.95 to attain the CQA criteria was calculated and verified successfully. Normal operating ranges of 8.2-10 g/g of W/M ratio, 1.25-1.63 h of extraction time, and two extractions were recommended. The optimized calculation conditions can conveniently be used in design space development for other pharmaceutical processes.
Mixed gradient-Tikhonov methods for solving nonlinear ill-posed problems in Banach spaces
Margotti, Fábio
2016-12-01
Tikhonov regularization is a very useful and widely used method for finding stable solutions of ill-posed problems. A good choice of the penalization functional as well as a careful selection of the topologies of the involved spaces is fundamental to the quality of the reconstructions. These choices can be combined with some a priori information about the solution in order to preserve desired characteristics like sparsity constraints for example. To prove convergence and stability properties of this method, one usually has to assume that a minimizer of the Tikhonov functional is known. In practical situations however, the exact computation of a minimizer is very difficult and even finding an approximation can be a very challenging and expensive task if the involved spaces have poor convexity or smoothness properties. In this paper we propose a method to attenuate this gap between theory and practice, applying a gradient-like method to a Tikhonov functional in order to approximate a minimizer. Using only available information, we explicitly calculate a maximal step-size which ensures a monotonically decreasing error. The resulting algorithm performs only finitely many steps and terminates using the discrepancy principle. In particular the knowledge of a minimizer or even its existence does not need to be assumed. Under standard assumptions, we prove convergence and stability results in relatively general Banach spaces, and subsequently, test its performance numerically, reconstructing conductivities with sparsely located inclusions and different kinds of noise in the 2D electrical impedance tomography.
Development of irradiation methods and degradation modeling for state-of-the-art space solar cells
Ohshima, Takeshi; Sato, Shin-ichiro; Sumita, Taishi; Nakamura, Tetsuya; Imaizumi, Mitsuru
2014-06-01
Japan Atomic Energy Agency (JAEA) together with Japan Aerospace Exploration Agency (JAXA) has developed an insitu evaluation technique for understanding radiation response of space solar cells, by which the electrical characteristics of solar cells can be measured under AM0 light illumination during proton/electron irradiation experiments (Simultaneous method). Using the simultaneous method, we revealed the radiation degradation of multi-junction solar cells such as InGaP/GaAs/Ge triple junction (3J) solar cells. A modeling of the radiation degradation of 3J solar cells based on the Non-Ionizing Energy Loss (NIEL) concept was established. Flexible multi-junction solar cells are under development for space applications.
Non-linear shape functions over time in the space-time finite element method
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Kacprzyk Zbigniew
2017-01-01
Full Text Available This work presents a generalisation of the space-time finite element method proposed by Kączkowski in his seminal of 1970’s and early 1980’s works. Kączkowski used linear shape functions in time. The recurrence formula obtained by Kączkowski was conditionally stable. In this paper, non-linear shape functions in time are proposed.
Steady flow of non-Newtonian fluids - monotonicity methods in generalized orlicz spaces
Czech Academy of Sciences Publication Activity Database
Wróblewska, Aneta
2010-01-01
Roč. 72, č. 11 (2010), s. 4136-4147 ISSN 0362-546X Institutional research plan: CEZ:AV0Z10190503 Keywords : non-Newtonian fluid * Orlicz spaces * modular convergence of symmetric gradients * general ized Minty method * smart fluids Subject RIV: BA - General Mathematics Impact factor: 1.279, year: 2010 http://www.sciencedirect.com/science/article/pii/S0362546X10000568
Local deformation method for measuring element tension in space deployable structures
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Belov Sergey
2017-01-01
Full Text Available The article describes the local deformation method to determine the tension of cord and thin membrane elements in space deployable structure as antenna reflector. Possible measuring instrument model, analytical and numerical solutions and experimental results are presented. The boundary effects on measurement results of metallic mesh reflector surface tension are estimated. The study case depicting non-uniform reflector surface tension is considered.
CMC-1 Surfaces in Hyperbolic 3-space using the Bianchi-Calo method
de Lima, Levi Lopes; Roitman, Pedro
2001-01-01
In this note we present a method for constructing CMC-1 surfaces in hyperbolic 3-space $\\bfH^3(-1)$ in terms of holomorphic data first introduced in Bianchi's Lezioni di Geometria Differenziale of 1927, therefore predating by many years the modern approaches due to Bryant, Small and others. Besides its obvious historical interest, this note aims to complement Bianchi's analysis by deriving explicit formulae for CMC-1 surfaces and comparing the various approaches encountered in the literature.
Constant mean curvature one surfaces in hyperbolic 3-space using the Bianchi-Calò method
LIMA LEVI L. DE; ROITMAN PEDRO
2002-01-01
In this note we present a method for constructing constant mean curvature on surfaces in hyperbolic 3-space in terms of holomorphic data first introduced in Bianchi's Lezioni di Geometria Differenziale of 1927, therefore predating by many years the modern approaches due to Bryant, Small and others. Besides its obvious historical interest, this note aims to complement Bianchi's analysis by deriving explicit formulae for CMC-1 surfaces and comparing the various approaches encountered in the lit...
Improving the space-domain methods of forward modeling for geodynamic studies by GRACE
DEFF Research Database (Denmark)
Strykowski, Gabriel
The present and future satellite missions CHAMP, GRACE and GOCE make it possible to study from space the local and the regional geophysical signals. This implies the revision of the methods of forward modelling of the gravitational attraction generated by known sources; e.g. the topography...... in the Nordic and Baltic countries for studying the post-glacial rebound in Scandinavia by the GRACE satellite....
Steady flow of non-Newtonian fluids - monotonicity methods in generalized orlicz spaces
Czech Academy of Sciences Publication Activity Database
Wróblewska, Aneta
2010-01-01
Roč. 72, č. 11 (2010), s. 4136-4147 ISSN 0362-546X Institutional research plan: CEZ:AV0Z10190503 Keywords : non-Newtonian fluid * Orlicz spaces * modular convergence of symmetric gradients * generalized Minty method * smart fluids Subject RIV: BA - General Mathematics Impact factor: 1.279, year: 2010 http://www.sciencedirect.com/science/article/pii/S0362546X10000568
METHOD OF GROUP OBJECTS FORMING FOR SPACE-BASED REMOTE SENSING OF THE EARTH
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A. N. Grigoriev
2015-07-01
Full Text Available Subject of Research. Research findings of the specific application of space-based optical-electronic and radar means for the Earth remote sensing are considered. The subject matter of the study is the current planning of objects survey on the underlying surface in order to increase the effectiveness of sensing system due to the rational use of its resources. Method. New concept of a group object, stochastic swath and stochastic length of the route is introduced. The overview of models for single, group objects and their parameters is given. The criterion for the existence of the group object based on two single objects is formulated. The method for group objects formation while current survey planning has been developed and its description is presented. The method comprises several processing stages for data about objects with the calculation of new parameters, the stochastic characteristics of space means and validates the spatial size of the object value of the stochastic swath and stochastic length of the route. The strict mathematical description of techniques for model creation of a group object based on data about a single object and onboard special complex facilities in difficult conditions of registration of spatial data is given. Main Results. The developed method is implemented on the basis of modern geographic information system in the form of a software tool layout with advanced tools of processing and analysis of spatial data in vector format. Experimental studies of the forming method for the group of objects were carried out on a different real object environment using the parameters of modern national systems of the Earth remote sensing detailed observation Canopus-B and Resurs-P. Practical Relevance. The proposed models and method are focused on practical implementation using vector spatial data models and modern geoinformation technologies. Practical value lies in the reduction in the amount of consumable resources by means of
A new method of effective training of crew members for long-term space mission
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Victor N. Skakov
2013-05-01
Full Text Available Aims The aim of the study is to select an effective method of system recovery of the organism for space pre-flight training to provide the normal long-term human stay in space. Materials and methods For this purpose, the method of acupuncture is used. Its distinctive feature is the needle acupuncture technique based on the fundamental knowledge of the classical Chinese Book of Changes. This technique was developed by Master of Traditional Chinese Medicine A.I. Falev (1953-2005 and improved by his followers. The above method allows awakening the energy of Chi in the human organism that in its turn initiates the therapeutic & health improving programs stored in the deepest layers of the human body nature. Results As a result of the Chi energy awakening, a complex of therapeutic & health improving reactions stored in the human body nature initiates. During the treatment, uncontrolled movements of the body and limbs appear, and the patient involuntarily performs some elements of point and remote energetic massage, self-manual therapy, yoga exercises, health-improving breathing exercises. The health-improving reactions appearing thereafter restore the proper circulation of Chi energy in the organism that leads to true recovery and full health restoration. Conclusion This method of treatment based on the ancient techniques of acupuncture, aimed at awakening the Chi energy in the organism, can be effectively used in an integrated program of systematic health improvement of crew members during long-term space missions. This method is very efficient, does not require expensive equipment and is based exclusively on releasing hidden reserves stored in the human body.
Method of the Determination of Exterior Orientation of Sensors in Hilbert Type Space.
Stępień, Grzegorz
2018-03-17
The following article presents a new isometric transformation algorithm based on the transformation in the newly normed Hilbert type space. The presented method is based on so-called virtual translations, already known in advance, of two relative oblique orthogonal coordinate systems-interior and exterior orientation of sensors-to a common, known in both systems, point. Each of the systems is translated along its axis (the systems have common origins) and at the same time the angular relative orientation of both coordinate systems is constant. The translation of both coordinate systems is defined by the spatial norm determining the length of vectors in the new Hilbert type space. As such, the displacement of two relative oblique orthogonal systems is reduced to zero. This makes it possible to directly calculate the rotation matrix of the sensor. The next and final step is the return translation of the system along an already known track. The method can be used for big rotation angles. The method was verified in laboratory conditions for the test data set and measurement data (field data). The accuracy of the results in the laboratory test is on the level of 10 -6 of the input data. This confirmed the correctness of the assumed calculation method. The method is a further development of the author's 2017 Total Free Station (TFS) transformation to several centroids in Hilbert type space. This is the reason why the method is called Multi-Centroid Isometric Transformation-MCIT. MCIT is very fast and enables, by reducing to zero the translation of two relative oblique orthogonal coordinate systems, direct calculation of the exterior orientation of the sensors.
Method of the Determination of Exterior Orientation of Sensors in Hilbert Type Space
Directory of Open Access Journals (Sweden)
Grzegorz Stępień
2018-03-01
Full Text Available The following article presents a new isometric transformation algorithm based on the transformation in the newly normed Hilbert type space. The presented method is based on so-called virtual translations, already known in advance, of two relative oblique orthogonal coordinate systems—interior and exterior orientation of sensors—to a common, known in both systems, point. Each of the systems is translated along its axis (the systems have common origins and at the same time the angular relative orientation of both coordinate systems is constant. The translation of both coordinate systems is defined by the spatial norm determining the length of vectors in the new Hilbert type space. As such, the displacement of two relative oblique orthogonal systems is reduced to zero. This makes it possible to directly calculate the rotation matrix of the sensor. The next and final step is the return translation of the system along an already known track. The method can be used for big rotation angles. The method was verified in laboratory conditions for the test data set and measurement data (field data. The accuracy of the results in the laboratory test is on the level of 10−6 of the input data. This confirmed the correctness of the assumed calculation method. The method is a further development of the author’s 2017 Total Free Station (TFS transformation to several centroids in Hilbert type space. This is the reason why the method is called Multi-Centroid Isometric Transformation—MCIT. MCIT is very fast and enables, by reducing to zero the translation of two relative oblique orthogonal coordinate systems, direct calculation of the exterior orientation of the sensors.
Ball convergence for Traub-Steffensen like methods in Banach space
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Argyros Ioannis K.
2015-12-01
Full Text Available We present a local convergence analysis for two Traub-Steffensen-like methods in order to approximate a locally unique solution of an equation in a Banach space setting. In earlier studies such as [16, 23] Taylor expansions and hypotheses up to the third Fréchet-derivative are used. We expand the applicability of these methods using only hypotheses on the first Fréchet derivative. Moreover, we obtain a radius of convergence and computable error bounds using Lipschitz constants not given before. Numerical examples are also presented in this study.
Chang, J. L. C.; Kwak, D.; Rogers, S. E.; Yang, R.-J.
1988-01-01
This paper discusses incompressible Navier-Stokes solution methods with an emphasis on the pseudocompressibility method. A steady-state flow solver based on the pseudocompressibility approach is then described. This flow solver code has been used to analyze the internal flow in the Space Shuttle main engine hot-gas manifold. Salient features associated with this three-dimensional realistic flow simulation are discussed. Numerical solutions relevant to the current engine analysis and the redesign effort are discussed along with experimental results. This example demonstrates the potential of computational fluid dynamics as a design tool for aerospace applications.
Inversion methods for fast-ion velocity-space tomography in fusion plasmas
DEFF Research Database (Denmark)
Jacobsen, Asger Schou; Stagner, L.; Salewski, Mirko
2016-01-01
Velocity-space tomography has been used to infer 2D fast-ion velocity distribution functions. Here we compare the performance of five different tomographic inversion methods: truncated singular value decomposition, maximum entropy, minimum Fisher information and zeroth and first-order Tikhonov re...... confidence regions, all methods agree that ions with pitch values close to zero, as well as ions with large pitch values, are ejected from the plasma center by the sawtooth crash, and that this ejection depletes the ion population with large pitch values more strongly....
DEFF Research Database (Denmark)
Kwon, Jun Bum; Wang, Xiongfei; Blaabjerg, Frede
2017-01-01
. Through this method, the required computation time and CPU memory can be reduced, where this faster simulation can be an advantage of a large network simulation. Besides, the achieved results show the same results as the non-linear time-domain simulation. Furthermore, the HSS modeling can describe how...... with different switching frequency or harmonics from ac-dc converters makes that harmonics and frequency coupling are both problems of ac system and challenges of dc system. This paper presents a modeling and simulation method for a large dc power electronic system by using Harmonic State Space (HSS) modeling...
Local convergence of a fifth convergence order method in Banach space
Directory of Open Access Journals (Sweden)
Ioannis K. Argyros
2017-07-01
Full Text Available We provide a local convergence analysis for a fifth convergence order method to find a solution of a nonlinear equation in a Banach space. In our paper the sufficient convergence conditions involve only hypotheses on the first Fréchet-derivative. Previous works use conditions reaching up to the fourth Fréchet-derivative. This way, the applicability of these methods is extended under weaker conditions and less computational cost for the Lipschitz constants appearing in the convergence analysis. Numerical examples are also given in this paper.
Electro-Optical Sensing Apparatus and Method for Characterizing Free-Space Electromagnetic Radiation
Zhang, Xi-Cheng; Libelo, Louis Francis; Wu, Qi
1999-09-14
Apparatus and methods for characterizing free-space electromagnetic energy, and in particular, apparatus/method suitable for real-time two-dimensional far-infrared imaging applications are presented. The sensing technique is based on a non-linear coupling between a low-frequency electric field and a laser beam in an electro-optic crystal. In addition to a practical counter-propagating sensing technique, a co-linear approach is described which provides longer radiated field--optical beam interaction length, thereby making imaging applications practical.
Impact mitigation using kinematic constraints and the full space parameterization method
Energy Technology Data Exchange (ETDEWEB)
Morgansen, K.A.; Pin, F.G.
1996-02-01
A new method for mitigating unexpected impact of a redundant manipulator with an object in its environment is presented. Kinematic constraints are utilized with the recently developed method known as Full Space Parameterization (FSP). System performance criterion and constraints are changed at impact to return the end effector to the point of impact and halt the arm. Since large joint accelerations could occur as the manipulator is halted, joint acceleration bounds are imposed to simulate physical actuator limitations. Simulation results are presented for the case of a simple redundant planar manipulator.
Recursive prediction error methods for online estimation in nonlinear state-space models
Directory of Open Access Journals (Sweden)
Dag Ljungquist
1994-04-01
Full Text Available Several recursive algorithms for online, combined state and parameter estimation in nonlinear state-space models are discussed in this paper. Well-known algorithms such as the extended Kalman filter and alternative formulations of the recursive prediction error method are included, as well as a new method based on a line-search strategy. A comparison of the algorithms illustrates that they are very similar although the differences can be important for the online tracking capabilities and robustness. Simulation experiments on a simple nonlinear process show that the performance under certain conditions can be improved by including a line-search strategy.
McGregor, Stephen; Agres, Kat; Purver, Matthew; Wiggins, Geraint A.
2015-12-01
We investigate the relationship between lexical spaces and contextually-defined conceptual spaces, offering applications to creative concept discovery. We define a computational method for discovering members of concepts based on semantic spaces: starting with a standard distributional model derived from corpus co-occurrence statistics, we dynamically select characteristic dimensions associated with seed terms, and thus a subspace of terms defining the related concept. This approach performs as well as, and in some cases better than, leading distributional semantic models on a WordNet-based concept discovery task, while also providing a model of concepts as convex regions within a space with interpretable dimensions. In particular, it performs well on more specific, contextualized concepts; to investigate this we therefore move beyond WordNet to a set of human empirical studies, in which we compare output against human responses on a membership task for novel concepts. Finally, a separate panel of judges rate both model output and human responses, showing similar ratings in many cases, and some commonalities and divergences which reveal interesting issues for computational concept discovery.
Analysis in Banach spaces volume II probabilistic methods and operator theory
Hytönen, Tuomas; Veraar, Mark; Weis, Lutz
2017-01-01
This second volume of Analysis in Banach Spaces, Probabilistic Methods and Operator Theory, is the successor to Volume I, Martingales and Littlewood-Paley Theory. It presents a thorough study of the fundamental randomisation techniques and the operator-theoretic aspects of the theory. The first two chapters address the relevant classical background from the theory of Banach spaces, including notions like type, cotype, K-convexity and contraction principles. In turn, the next two chapters provide a detailed treatment of the theory of R-boundedness and Banach space valued square functions developed over the last 20 years. In the last chapter, this content is applied to develop the holomorphic functional calculus of sectorial and bi-sectorial operators in Banach spaces. Given its breadth of coverage, this book will be an invaluable reference to graduate students and researchers interested in functional analysis, harmonic analysis, spectral theory, stochastic analysis, and the operator-theoretic approac...
Method and apparatus for dual-spaced fast/epithermal neutron porosity measurements
International Nuclear Information System (INIS)
Smith, H.D. Jr.
1986-01-01
A method is described for determining the porosity of earth formations in the vicinity of a well borehole, comprising: (a) irradiating the earth formations in the vicinity of the well borehole with a continuous chemical type source of fast neutrons, (b) detecting the fast neutron population at a first shorter spaced distance from the neutron source in the borehole and generating signals representative thereof, (c) detecting the epithermal neutron population at a second space distance from the neutron source in the borehole and generating signals representative thereof, the second spaced distance being greater than the first spaced distance from the neutron source, (d) forming a ratio of the signals representing the fast and epithermal neutron populations to derive a measurement signal functionally related to the porosity of the earth formations in the vicinity of the borehole, and (e) calibrating the measurement signal according to a predetermined functional relationship to derive a porosity signal quantitatively representative of the porosity of the earth formations in the vicinity of the borehole
Directory of Open Access Journals (Sweden)
Pedro Brandão
2015-06-01
• In the development of design practice and studio teaching methods We shall see in this paper how interdisciplinary approaches correspond to new and complex urban transformations, focusing on the importance of actors’ interaction processes, combining professional and non-professional knowledge and theory-practice relations. Therefore, we aim at a deepening in public space area of knowledge under the growing complexity of urban life. We see it as a base for further development of collaborative projects and their implications on community empowerment and urban governance at local level. Motivations of this line of work are persistent in several ongoing research projects, aiming to: - Understand public space as a cohesion factor both in urban life and urban form - Manage processes and strategies as elements of urban transformation, - Stimulate the understanding of actors’ roles in urban design practices. - Favoring the questioning of emerging aspects of urban space production… The paper presents and analyses processes, methods and results from civic participation projects developed in the neighbourhood of Barò de Viver (Barcelona and in the District of Marvila (Lisbon. In the first case, a long process initiated in 2004 and partially completed in 2011, neighbours developed the projects "Memory Wall" and Ciutat d'Asuncion Promenade as part of identity construction in public space, in collaboration with a team of facilitators from CrPolis group. In the second case, different participatory processes dated from 2001 and 2003 have resulted in the implementation of a specific identity urban brand and communication system with an ongoing project of "maps" construction according to the neighbours perception and representation systems. We may conclude that processes of urban governance require more active participation of citizens in projects regarding the improvement of quality of life. At the same time, the implementation of these processes requires a clear
Directory of Open Access Journals (Sweden)
Lee Hotaik
2006-10-01
Full Text Available Abstract Background Ultrasound induced hyperthermia is a useful adjuvant to radiation therapy in the treatment of prostate cancer. A uniform thermal dose (43°C for 30 minutes is required within the targeted cancerous volume for effective therapy. This requires specific ultrasound phased array design and appropriate thermometry method. Inhomogeneous, acoustical, three-dimensional (3D prostate models and economical computational methods provide necessary tools to predict the appropriate shape of hyperthermia phased arrays for better focusing. This research utilizes the k-space computational method and a 3D human prostate model to design an intracavitary ultrasound probe for hyperthermia treatment of prostate cancer. Evaluation of the probe includes ex vivo and in vivo controlled hyperthermia experiments using the noninvasive magnetic resonance imaging (MRI thermometry. Methods A 3D acoustical prostate model was created using photographic data from the Visible Human Project®. The k-space computational method was used on this coarse grid and inhomogeneous tissue model to simulate the steady state pressure wavefield of the designed phased array using the linear acoustic wave equation. To ensure the uniformity and spread of the pressure in the length of the array, and the focusing capability in the width of the array, the equally-sized elements of the 4 × 20 elements phased array were 1 × 14 mm. A probe was constructed according to the design in simulation using lead zerconate titanate (PZT-8 ceramic and a Delrin® plastic housing. Noninvasive MRI thermometry and a switching feedback controller were used to accomplish ex vivo and in vivo hyperthermia evaluations of the probe. Results Both exposimetry and k-space simulation results demonstrated acceptable agreement within 9%. With a desired temperature plateau of 43.0°C, ex vivo and in vivo controlled hyperthermia experiments showed that the MRI temperature at the steady state was 42.9 ± 0.38
Chai, Runqi; Savvaris, Al; Tsourdos, Antonios
2016-06-01
In this paper, a fuzzy physical programming (FPP) method has been introduced for solving multi-objective Space Manoeuvre Vehicles (SMV) skip trajectory optimization problem based on hp-adaptive pseudospectral methods. The dynamic model of SMV is elaborated and then, by employing hp-adaptive pseudospectral methods, the problem has been transformed to nonlinear programming (NLP) problem. According to the mission requirements, the solutions were calculated for each single-objective scenario. To get a compromised solution for each target, the fuzzy physical programming (FPP) model is proposed. The preference function is established with considering the fuzzy factor of the system such that a proper compromised trajectory can be acquired. In addition, the NSGA-II is tested to obtain the Pareto-optimal solution set and verify the Pareto optimality of the FPP solution. Simulation results indicate that the proposed method is effective and feasible in terms of dealing with the multi-objective skip trajectory optimization for the SMV.
International Nuclear Information System (INIS)
Leote, Joao; Nunes, Rita; Cerqueira, Luis; Ferreira, Hugo Alexandre
2015-01-01
Recently, DKI-based tractography has been developed, showing improved crossing-fiber resolution in comparison to deterministic DTI-based tractography in healthy subjects. In this work, DTI and DKI-based tractography methods were compared regarding the assessment of the corticospinal tract in patients presenting space-occupying brain lesions near cortical motor areas. Nine patients (4 males) aged 23 to 62 years old, with space-occupying brain lesions (e.g. tumors) were studied for pre-surgical planning using a 1.5T MRI scanner and a 12-channel head coil. In 5 patients diffusion data was acquired along 64 directions and in 4 patients along 32 directions both with b-values 0, 1000 and 2000 s/mm2. Corticospinal tracts were estimated using deterministic DTI and DKI methods and also using probabilistic DTI. The superior cerebellar peduncles and the motor cortical areas, ipsilateral and contralateral to the lesions, were used as seed regions-of-interest for fiber tracking. Tracts courses and volumes were documented and compared between methods. Results showed that it was possible to estimate fiber tracts using deterministic DTI and DKI methods in 8/9 patients, and using the probabilistic DTI method in all patients. Overall, it was observed that DKI-based tractography showed more voluminous fiber tracts than when using deterministic DTI. The DKI method also showed curvilinear fibers mainly above lesions margins, which were not visible with deterministic DTI in 5 patients. Similar tracts were observed when using probabilistic DTI in 3 of those patients. Results suggest that the DKI method contribute with additional information about the corticospinal tract course in comparison with the DTI method, especially with subcortical lesions and near lesions’ margins. Therefore, this study suggests that DKI-based tractography could be useful in MRI and hybrid PET-MRI pre-surgical planning protocols for improved corticospinal tract evaluation.
Zhang, Jian; Zhang, Xin; Bi, Yu-An; Xu, Gui-Hong; Huang, Wen-Zhe; Wang, Zhen-Zhong; Xiao, Wei
2017-09-01
The "design space" method was used to optimize the purification process of Resina Draconis phenol extracts by using the concept of "quality derived from design" (QbD). The content and transfer rate of laurin B and 7,4'-dihydroxyflavone and yield of extract were selected as the critical quality attributes (CQA). Plackett-Burman design showed that the critical process parameters (CPP) were concentration of alkali, the amount of alkali and the temperature of alkali dissolution. Then the Box-Behnken design was used to establish the mathematical model between CQA and CPP. The variance analysis results showed that the P values of the five models were less than 0.05 and the mismatch values were all greater than 0.05, indicating that the model could well describe the relationship between CQA and CPP. Finally, the control limits of the above 5 indicators (content and transfer rate of laurine B and 7,4'-dihydroxyflavone, as well as the extract yield) were set, and then the probability-based design space was calculated by Monte Carlo simulation and verified. The results of the design space validation showed that the optimized purification method can ensure the stability of the Resina Draconis phenol extracts refining process, which would help to improve the quality uniformity between batches of phenol extracts and provide data support for production automation control. Copyright© by the Chinese Pharmaceutical Association.
Research into topology optimization and the FDM method for a space cracked membrane
Hu, Qingxi; Li, Wanyuan; Zhang, Haiguang; Liu, Dali; Peng, Fujun; Duan, Yongchao
2017-07-01
The problem that the space membranes are easily torn open is the main focus in this paper, and a bionic strengthening-ribs structure is proposed for a space membrane based on interdisciplinary strengths, such as topology optimization, composite materials, and rapid prototyping. The optimization method and modeling method of membranes with bionic strengthening-ribs was studied. The PEEK and SCF/PEEK composite material which are applied to the space environment are chosen, and FDM technology is used. Through topology optimization, bionic strengthening-ribs with good tensile and tear capacities were obtained. Cracked membranes, cracked membranes with PEEK strengthening-ribs and SCF/PEEK strengthening-ribs were tested and test data were obtained. An extension situation and tension fracture were compared for three cases. The experimental results showed that membranes with the bionic strengthening-ribs structure have better mechanical properties, and the strength of the membranes with PEEK and SCF/PEEK strengthening-ribs were raised, respectively, up to 266.9% and 185.9%. The strengthening-ribs structure greatly improves the capacity to halt membrane crack-growth, which has an important significance to avoid membrane tear, and to ensure the spacecraft orbital lifetime.
Lu, Chao; Li, Xubin; Wu, Dongsheng; Zheng, Lianqing; Yang, Wei
2016-01-12
In aqueous solution, solute conformational transitions are governed by intimate interplays of the fluctuations of solute-solute, solute-water, and water-water interactions. To promote molecular fluctuations to enhance sampling of essential conformational changes, a common strategy is to construct an expanded Hamiltonian through a series of Hamiltonian perturbations and thereby broaden the distribution of certain interactions of focus. Due to a lack of active sampling of configuration response to Hamiltonian transitions, it is challenging for common expanded Hamiltonian methods to robustly explore solvent mediated rare conformational events. The orthogonal space sampling (OSS) scheme, as exemplified by the orthogonal space random walk and orthogonal space tempering methods, provides a general framework for synchronous acceleration of slow configuration responses. To more effectively sample conformational transitions in aqueous solution, in this work, we devised a generalized orthogonal space tempering (gOST) algorithm. Specifically, in the Hamiltonian perturbation part, a solvent-accessible-surface-area-dependent term is introduced to implicitly perturb near-solute water-water fluctuations; more importantly in the orthogonal space response part, the generalized force order parameter is generalized as a two-dimension order parameter set, in which essential solute-solvent and solute-solute components are separately treated. The gOST algorithm is evaluated through a molecular dynamics simulation study on the explicitly solvated deca-alanine (Ala10) peptide. On the basis of a fully automated sampling protocol, the gOST simulation enabled repetitive folding and unfolding of the solvated peptide within a single continuous trajectory and allowed for detailed constructions of Ala10 folding/unfolding free energy surfaces. The gOST result reveals that solvent cooperative fluctuations play a pivotal role in Ala10 folding/unfolding transitions. In addition, our assessment
A fast nonstationary iterative method with convex penalty for inverse problems in Hilbert spaces
Jin, Qinian; Lu, Xiliang
2014-04-01
In this paper we consider the computation of approximate solutions for inverse problems in Hilbert spaces. In order to capture the special feature of solutions, non-smooth convex functions are introduced as penalty terms. By exploiting the Hilbert space structure of the underlying problems, we propose a fast iterative regularization method which reduces to the classical nonstationary iterated Tikhonov regularization when the penalty term is chosen to be the square of norm. Each iteration of the method consists of two steps: the first step involves only the operator from the problem while the second step involves only the penalty term. This splitting character has the advantage of making the computation efficient. In case the data is corrupted by noise, a stopping rule is proposed to terminate the method and the corresponding regularization property is established. Finally, we test the performance of the method by reporting various numerical simulations, including the image deblurring, the determination of source term in Poisson equation, and the de-autoconvolution problem.
A fast nonstationary iterative method with convex penalty for inverse problems in Hilbert spaces
International Nuclear Information System (INIS)
Jin, Qinian; Lu, Xiliang
2014-01-01
In this paper we consider the computation of approximate solutions for inverse problems in Hilbert spaces. In order to capture the special feature of solutions, non-smooth convex functions are introduced as penalty terms. By exploiting the Hilbert space structure of the underlying problems, we propose a fast iterative regularization method which reduces to the classical nonstationary iterated Tikhonov regularization when the penalty term is chosen to be the square of norm. Each iteration of the method consists of two steps: the first step involves only the operator from the problem while the second step involves only the penalty term. This splitting character has the advantage of making the computation efficient. In case the data is corrupted by noise, a stopping rule is proposed to terminate the method and the corresponding regularization property is established. Finally, we test the performance of the method by reporting various numerical simulations, including the image deblurring, the determination of source term in Poisson equation, and the de-autoconvolution problem. (paper)
Directory of Open Access Journals (Sweden)
Qiuming Cheng
2007-06-01
Full Text Available The patterns shown on two-dimensional images (fields used in geosciences reflect the end products of geo-processes that occurred on the surface and in the subsurface of the Earth. Anisotropy of these types of patterns can provide information useful for interpretation of geo-processes and identification of features in the mapped area. Quantification of the anisotropy property is therefore essential for image processing and interpretation. This paper introduces several techniques newly developed on the basis of multifractal modeling in space, Fourier frequency, and eigen domains, respectively. A singularity analysis method implemented in the space domain can be used to quantify the intensity and anisotropy of local singularities. The second method, called S-A, characterizes the generalized scale invariance property of a field in the Fourier frequency domain. The third method characterizes the field using a power-law model on the basis of eigenvalues and eigenvectors of the field. The applications of these methods are demonstrated with a case study of Environment Scan Electric Microscope (ESEM microimages for identification of sphalerite (ZnS ore minerals from the Jinding Pb/Zn/Ag mineral deposit in Shangjiang District, Yunnan Province, China.
Super-High Resolution Time Interval Measurement Method Based on Time-Space Relationships
International Nuclear Information System (INIS)
Bao-Qiang, Du; Wei, Zhou
2009-01-01
Based on the principle of quantized delay-time, a super-high resolution time interval measurement method is proposed based on time-space relationships. Using the delay-time stability that time and frequency signal travel in a specific medium, the measured time interval can be quantized. Combined with the phase coincidence detection technique, the measurement of time can be changed into the measurement of space length. The resolution and the stability of the measurement system are easily improved. Experimental results show that the measurement resolution of the measured time interval depends on the length difference of the double delay-time unit. When the length difference is set up on millimeter level or sub-millimeter level, super-high measurement resolution from hundreds of picosecond to tens of picosecond can be obtained
Scalable implicit methods for reaction-diffusion equations in two and three space dimensions
Energy Technology Data Exchange (ETDEWEB)
Veronese, S.V.; Othmer, H.G. [Univ. of Utah, Salt Lake City, UT (United States)
1996-12-31
This paper describes the implementation of a solver for systems of semi-linear parabolic partial differential equations in two and three space dimensions. The solver is based on a parallel implementation of a non-linear Alternating Direction Implicit (ADI) scheme which uses a Cartesian grid in space and an implicit time-stepping algorithm. Various reordering strategies for the linearized equations are used to reduce the stride and improve the overall effectiveness of the parallel implementation. We have successfully used this solver for large-scale reaction-diffusion problems in computational biology and medicine in which the desired solution is a traveling wave that may contain rapid transitions. A number of examples that illustrate the efficiency and accuracy of the method are given here; the theoretical analysis will be presented.
Fano, Guido
2017-01-01
This book is designed to make accessible to nonspecialists the still evolving concepts of quantum mechanics and the terminology in which these are expressed. The opening chapters summarize elementary concepts of twentieth century quantum mechanics and describe the mathematical methods employed in the field, with clear explanation of, for example, Hilbert space, complex variables, complex vector spaces and Dirac notation, and the Heisenberg uncertainty principle. After detailed discussion of the Schrödinger equation, subsequent chapters focus on isotropic vectors, used to construct spinors, and on conceptual problems associated with measurement, superposition, and decoherence in quantum systems. Here, due attention is paid to Bell’s inequality and the possible existence of hidden variables. Finally, progression toward quantum computation is examined in detail: if quantum computers can be made practicable, enormous enhancements in computing power, artificial intelligence, and secure communication will result...
Method of phase space beam dilution utilizing bounded chaos generated by rf phase modulation
Directory of Open Access Journals (Sweden)
Alfonse N. Pham
2015-12-01
Full Text Available This paper explores the physics of chaos in a localized phase-space region produced by rf phase modulation applied to a double rf system. The study can be exploited to produce rapid particle bunch broadening exhibiting longitudinal particle distribution uniformity. Hamiltonian models and particle-tracking simulations are introduced to understand the mechanism and applicability of controlled particle diffusion. When phase modulation is applied to the double rf system, regions of localized chaos are produced through the disruption and overlapping of parametric resonant islands and configured to be bounded by well-behaved invariant tori to prevent particle loss. The condition of chaoticity and the degree of particle dilution can be controlled by the rf parameters. The method has applications in alleviating adverse space-charge effects in high-intensity beams, particle bunch distribution uniformization, and industrial radiation-effects experiments.
RESEARCH INTO PSYCHOLOGICAL EVALUATION METHOD OF UNDERGROUND SPACE - CENTERING ON THE TOKYO METRO -
Yoshimoto, Naomi; Wake, Tenji; Mita, Takeshi; Wake, Hiromi
This research is concerned with developing evaluation methods that can be useful for environmental design from the psychological perspective of QOL, that is comfort, in underground space. For this research, eight stations on the Tokyo Metro, including the Fukutoshin line, were selected and two types of questionnaires were carried out after respondents had walked through the station areas and the walkways connecting the stations. From the results of the first questionnaire, four factors, comfort/convenience, insecurity, visibility/noticeability, brightness/ease of walking, were extracted. From the results of the second questionnaire, three factors were extracted: visibility of noticeboards, overall atmosphere of underground space, visibility of fare chart/subway map. There was a strong correlation between the factors comfort/convenience and insecurity, extracted from the first questionnaire, and the overall atmosphere factor extracted from the second questionnaire. For visibility/noticeability, there was a strong correlation with notices, fares chart, and subway map.
A New Ensemble Method with Feature Space Partitioning for High-Dimensional Data Classification
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Yongjun Piao
2015-01-01
Full Text Available Ensemble data mining methods, also known as classifier combination, are often used to improve the performance of classification. Various classifier combination methods such as bagging, boosting, and random forest have been devised and have received considerable attention in the past. However, data dimensionality increases rapidly day by day. Such a trend poses various challenges as these methods are not suitable to directly apply to high-dimensional datasets. In this paper, we propose an ensemble method for classification of high-dimensional data, with each classifier constructed from a different set of features determined by partitioning of redundant features. In our method, the redundancy of features is considered to divide the original feature space. Then, each generated feature subset is trained by a support vector machine, and the results of each classifier are combined by majority voting. The efficiency and effectiveness of our method are demonstrated through comparisons with other ensemble techniques, and the results show that our method outperforms other methods.
Inversion methods for fast-ion velocity-space tomography in fusion plasmas
DEFF Research Database (Denmark)
Jacobsen, Asger Schou; Stagner, L.; Salewski, Mirko
2016-01-01
Velocity-space tomography has been used to infer 2D fast-ion velocity distribution functions. Here we compare the performance of five different tomographic inversion methods: truncated singular value decomposition, maximum entropy, minimum Fisher information and zeroth and first-order Tikhonov...... regularization. The inversion methods are applied to fast-ion Dα measurements taken just before and just after a sawtooth crash in the ASDEX Upgrade tokamak as well as to synthetic measurements from different test distributions. We find that the methods regularizing by penalizing steep gradients or maximizing...... entropy perform best. We assess the uncertainty of the calculated inversions taking into account photon noise, uncertainties in the forward model as well as uncertainties introduced by the regularization which allows us to distinguish regions of high and low confidence in the tomographies. In high...
A Parallel Strategy for High-speed Interpolation of CNC Using Data Space Constraint Method
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Shuan-qiang Yang
2013-12-01
Full Text Available A high-speed interpolation scheme using parallel computing is proposed in this paper. The interpolation method is divided into two tasks, namely, the rough task executing in PC and the fine task in the I/O card. During the interpolation procedure, the double buffers are constructed to exchange the interpolation data between the two tasks. Then, the data space constraint method is adapted to ensure the reliable and continuous data communication between the two buffers. Therefore, the proposed scheme can be realized in the common distribution of the operation systems without real-time performance. The high-speed and high-precision motion control can be achieved as well. Finally, an experiment is conducted on the self-developed CNC platform, the test results are shown to verify the proposed method.
Correlating the EMC analysis and testing methods for space systems in MIL-STD-1541A
Perez, Reinaldo J.
A study was conducted to improve the correlation between the electromagnetic compatibility (EMC) analysis models stated in MIL-STD-1541A and the suggested testing methods used for space systems. The test and analysis methods outlined in MIL-STD-1541A are described, and a comparative assessment of testing and analysis techniques as they relate to several EMC areas is presented. Suggestions on present analysis and test methods are introduced to harmonize and bring the analysis and testing tools in MIL-STD-1541A into closer agreement. It is suggested that test procedures in MIL-STD-1541A must be improved by providing alternatives to the present use of shielded enclosures as the primary site for such tests. In addition, the alternate use of anechoic chambers and open field test sites must be considered.
Correlating the EMC analysis and testing methods for space systems in MIL-STD-1541A
Perez, Reinaldo J.
1990-01-01
A study was conducted to improve the correlation between the electromagnetic compatibility (EMC) analysis models stated in MIL-STD-1541A and the suggested testing methods used for space systems. The test and analysis methods outlined in MIL-STD-1541A are described, and a comparative assessment of testing and analysis techniques as they relate to several EMC areas is presented. Suggestions on present analysis and test methods are introduced to harmonize and bring the analysis and testing tools in MIL-STD-1541A into closer agreement. It is suggested that test procedures in MIL-STD-1541A must be improved by providing alternatives to the present use of shielded enclosures as the primary site for such tests. In addition, the alternate use of anechoic chambers and open field test sites must be considered.
A self-consistent TB-LMTO-augmented space recursion method for disordered binary alloys
Chakrabarti, A.; Mookerjee, A.
2005-03-01
We developed a complete self-consistent TB-LMTO-Augmented space recursion (ASR) method for calculating configurational average properties of substitutionally disordered binary alloys. We applied our method to fcc based Cu-Ni, Ag-Pd for different concentrations of constituent elements and body-centered cubic based ferromagnetic Fe-V (50-50) alloy. For this systems we investigated the convergence of total energy and l-dependent potential parameters, charges, magnetic moment, energy moments of density of states with the number of iterations. Our results show good agreement with the existing calculations and also with the experimental results where it is available. The Madelung energy correction due to the charge transfer has also been included by the method developed by Ruban et al.
Error Analysis of a Finite Element Method for the Space-Fractional Parabolic Equation
Jin, Bangti
2014-01-01
© 2014 Society for Industrial and Applied Mathematics We consider an initial boundary value problem for a one-dimensional fractional-order parabolic equation with a space fractional derivative of Riemann-Liouville type and order α ∈ (1, 2). We study a spatial semidiscrete scheme using the standard Galerkin finite element method with piecewise linear finite elements, as well as fully discrete schemes based on the backward Euler method and the Crank-Nicolson method. Error estimates in the L2(D)- and Hα/2 (D)-norm are derived for the semidiscrete scheme and in the L2(D)-norm for the fully discrete schemes. These estimates cover both smooth and nonsmooth initial data and are expressed directly in terms of the smoothness of the initial data. Extensive numerical results are presented to illustrate the theoretical results.
Mustapha, K.
2017-06-03
Anomalous diffusion is a phenomenon that cannot be modeled accurately by second-order diffusion equations, but is better described by fractional diffusion models. The nonlocal nature of the fractional diffusion operators makes substantially more difficult the mathematical analysis of these models and the establishment of suitable numerical schemes. This paper proposes and analyzes the first finite difference method for solving {\\\\em variable-coefficient} fractional differential equations, with two-sided fractional derivatives, in one-dimensional space. The proposed scheme combines first-order forward and backward Euler methods for approximating the left-sided fractional derivative when the right-sided fractional derivative is approximated by two consecutive applications of the first-order backward Euler method. Our finite difference scheme reduces to the standard second-order central difference scheme in the absence of fractional derivatives. The existence and uniqueness of the solution for the proposed scheme are proved, and truncation errors of order $h$ are demonstrated, where $h$ denotes the maximum space step size. The numerical tests illustrate the global $O(h)$ accuracy of our scheme, except for nonsmooth cases which, as expected, have deteriorated convergence rates.
Fernand Braudel and Formation of Geohistorical Method in the Study of Economic Space
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Alexander Nikolaevich Demyanenko
2013-09-01
Full Text Available The essay analyzes the part of the scientific extensive heritage of F. Braudel which is devoted to formation of geohistorical method as a methodological platform that allows realization of the idea of interdisciplinary synthesis in the study of economic space. The very name of the method contains a direct reference to the synthesis of geographical and historical approaches to the study of society and economy. For its part, the introduction of geographical approaches in the framework of interdisciplinary synthesis involves not only the introduction of space in the analysis of economic phenomena, but also the inclusion of geographical environment. That in turn requires consideration of extension in time during the analysis of spatial economic systems because temporal rhythms are usually ignored by economists in view of their duration. At the same time, neglect or time constraints hindered and keep hindering the development of economic thought. The authors paid special attention to analysis of the matter of the monograph «The Mediterranean and the Mediterranean World in the Age of Philip II» which is a landmark work both for historical and economic sciences as it pioneered the substantiation of the geohistorical method
Wang, Geng; Xing, Fei; Wei, Minsong; Sun, Ting; You, Zheng
2017-05-20
Star trackers, optical attitude sensors with high precision, are susceptible to space light from the Sun and the Earth albedo. Until now, research in this field has lacked systematic analysis. In this paper, we propose an installation orientation method for a star tracker onboard sun-synchronous-orbit spacecraft and analyze the space light distribution by transforming the complicated relative motion among the Sun, Earth, and the satellite to the body coordinate system of the satellite. Meanwhile, the boundary-curve equations of the areas exposed to the stray light from the Sun and the Earth albedo were calculated by the coordinate-transformation matrix under different maneuver attitudes, and the installation orientation of the star tracker was optimized based on the boundary equations instead of the traditional iterative simulation method. The simulation and verification experiment indicate that this installation orientation method is effective and precise and can provide a reference for the installation of sun-synchronous orbit star trackers free from the stray light.
Pérez-González, Rocío; Gauthier, Sebastien A; Kumar, Asok; Saito, Mitsuo; Saito, Mariko; Levy, Efrat
2017-01-01
Extracellular vesicles (EV), including exosomes, secreted vesicles of endocytic origin, and microvesicles derived from the plasma membrane, have been widely isolated and characterized from conditioned culture media and bodily fluids. The difficulty in isolating EV from tissues, however, has hindered their study in vivo. Here, we describe a novel method designed to isolate EV and characterize exosomes from the extracellular space of brain tissues. The purification of EV is achieved by gentle dissociation of the tissue to free the brain extracellular space, followed by sequential low-speed centrifugations, filtration, and ultracentrifugations. To further purify EV from other extracellular components, they are separated on a sucrose step gradient. Characterization of the sucrose step gradient fractions by electron microscopy demonstrates that this method yields pure EV preparations free of large vesicles, subcellular organelles, or debris. The level of EV secretion and content are determined by assays for acetylcholinesterase activity and total protein estimation, and exosomal identification and protein content are analyzed by Western blot and immuno-electron microscopy. Additionally, we present here a method to delipidate EV in order to improve the resolution of downstream electrophoretic analysis of EV proteins.
3D shape detection of the indoor space based on 3D-Hough method
安齋, 達也; ANZAI, Tatsuya
2013-01-01
This paper describes methods for detecting the 3D shapes of the indoor space that is represented as a combination of planes such as a wall, desk, or whatnot. Detecting the planes makes it possible to perform calibration of multiple sensors and 3D mapping, and then produces various services such as the acquisition of life logs, AR interaction, and invader detection. This paper proposes and verifies three algorithms. First, it mentions a way to use2D-Hough.The proposed technique converts 3D dat...
The study of importance of the storage method of the space foods
Katayama, Naomi; Yamashita, Masamichi; Space Agriculture Task Force, J.
Providing foods to space crew is the important requirements to support long term manned space exploration. Foods fill not only physiological requirements to sustain life, but psychological needs for refreshment and joy during the long and hard mission to extraterrestrial planets. In the space stay of the long term, the storage technology of the food is important. Surplus food and the establishment of a safe save method of the food are essential. However, in Moon and Mars base or spaceship, there are limited spaces. We need to think about how to use the storage food when we have the time of emergency. The fundamental composition of our recipe is unpolished rice, barley, soybean, sweat potato and green-yellow vegetables. Supplement food materials to fulfill the nutritional requirements we chose are loach, silkworm pupa, termite, snail, mud snail, bee, cassava and quinoa. The pupa of the silkworm becomes the important nourishment source as protein and lipid. The silk thread uses it as clothing and cosmetics and medical supplies. However, we can use the silk thread as food as protein. The silk thread is mad of sericin and fibroin. The sericin is used for cosmetics mainly, but can make sheet food by mixing it with rice flour. We can make Japanese rolled sushi with this product. In addition, we can make spring roll and gyoza and shao-mai. As for the fibroin which is the subject of the silk thread, is to extract it high pressure heat; of the protein can powder it, and can use it as food. Even if there is the silk thread in this way after having made it clothes once, we can do it to food again. We can reuse the cotton thread as carbohydrates equally, too. We can use the wood as carbohydrates, also. Based upon the foregoing, we use the pupa of the silkworm as protein and lipid, and the silk thread as protein, and the cotton thread and wood as carbohydrates. It is recommended as healthy meal balance; Protein: Lipid: Carbohydrate ratio equal 15We succeeded to develop joyful
Combining local scaling and global methods to detect soil pore space
Martin-Sotoca, Juan Jose; Saa-Requejo, Antonio; Grau, Juan B.; Tarquis, Ana M.
2017-04-01
The characterization of the spatial distribution of soil pore structures is essential to obtain different parameters that will influence in several models related to water flow and/or microbial growth processes. The first step in pore structure characterization is obtaining soil images that best approximate reality. Over the last decade, major technological advances in X-ray computed tomography (CT) have allowed for the investigation and reconstruction of natural porous media architectures at very fine scales. The subsequent step is delimiting the pore structure (pore space) from the CT soil images applying a thresholding. Many times we could find CT-scan images that show low contrast at the solid-void interface that difficult this step. Different delimitation methods can result in different spatial distributions of pores influencing the parameters used in the models. Recently, new local segmentation method using local greyscale value (GV) concentration variabilities, based on fractal concepts, has been presented. This method creates singularity maps to measure the GV concentration at each point. The C-A method was combined with the singularity map approach (Singularity-CA method) to define local thresholds that can be applied to binarize CT images. Comparing this method with classical methods, such as Otsu and Maximum Entropy, we observed that more pores can be detected mainly due to its ability to amplify anomalous concentrations. However, it delineated many small pores that were incorrect. In this work, we present an improve version of Singularity-CA method that avoid this problem basically combining it with the global classical methods. References Martín-Sotoca, J.J., A. Saa-Requejo, J.B. Grau, A.M. Tarquis. New segmentation method based on fractal properties using singularity maps. Geoderma, 287, 40-53, 2017. Martín-Sotoca, J.J, A. Saa-Requejo, J.B. Grau, A.M. Tarquis. Local 3D segmentation of soil pore space based on fractal properties using singularity
Introduction to real-space renormalization-group methods in critical and chaotic phenomena
Hu, Bambi
1982-11-01
The methods of the real-space renormalization group, and their application to critical and chaotic phenomena are reviewed. The article consists of two parts: the first part deals with phase transitions and critical phenomena; the second part, bifurcations and transitions to chaos. We begin with an introduction to the phenomenology of phase transitions and critical phenomena. Seminal concepts such as scaling and universality, and their characterization by critical exponents are discussed. The basic ideas of the renormalization group are then explained. A survey of real-space renormalization-group methods: decimation, Migdal-Kadanoff approximation, cumulant and cluster expansions, is given. The Hamiltonian formulation of classical statistical systems into quantum mechanical systems by the method of the transfer matrix is introduced. Quantum renormalization-group methods of truncation and projection, and their application to the transcribed quantum mechanical Ising model in a transverse field are illustrated. Finally, the quantum cumulant-expansion method as applied to the one-dimensional quantum mechanical XY model is discussed. The second part of the article is devoted to the subject of bifurcations and transitions to chaos. The three most commonly discussed kinds of bifurcations: the pitchfork, tangent and Hopf bifurcations, and the associated routes to chaos: period doubling, intermittency and quasiperiodicity are discussed. Period doubling based on the logistic map is explained in detail. Universality and its expression in terms of functional renormalization-group equations is discussed. The Liapunov characteristic exponent and its analogy to the order parameter are introduced. The effect of external noise and its universal scaling feature are shown. The simplest characterizations of the Hénon strange attractor are intuitively illustrated. The purpose of this article is primarily pedagogical. The similarity between critical and chaotic phenomena is a recurrent
Transient Response of Thin Wire above a Layered Half-Space Using TDIE/FDTD Hybrid Method
Directory of Open Access Journals (Sweden)
Bing Wei
2012-01-01
Full Text Available The TDIE/FDTD hybrid method is applied to calculate the transient responses of thin wire above a lossy layered half-space. The time-domain reflection of the layered half space is computed by one-dimensional modified FDTD method. Then, transient response of thin wire induced by two excitation sources (the incident wave and reflected wave is calculated by TDIE method. Finally numerical results are given to illustrate the feasibility and high efficiency of the presented scheme.
Antonille, Scott R.; Miskey, Cherie L.; Ohl, Raymond G.; Rohrbach, Scott O.; Aronstein, David L.; Bartoszyk, Andrew E.; Bowers, Charles W.; Cofie, Emmanuel; Collins, Nicholas R.; Comber, Brian J.;
2016-01-01
NASA's James Webb Space Telescope (JWST) is a 6.6m diameter, segmented, deployable telescope for cryogenic IR space astronomy (40K). The JWST Observatory includes the Optical Telescope Element (OTE) and the Integrated Science Instrument Module (ISIM) that contains four science instruments (SI) and the fine guider. The SIs are mounted to a composite metering structure. The SI and guider units were integrated to the ISIM structure and optically tested at the NASA Goddard Space Flight Center as a suite using the Optical Telescope Element SIMulator (OSIM). OSIM is a full field, cryogenic JWST telescope simulator. SI performance, including alignment and wave front error, were evaluated using OSIM. We describe test and analysis methods for optical performance verification of the ISIM Element, with an emphasis on the processes used to plan and execute the test. The complexity of ISIM and OSIM drove us to develop a software tool for test planning that allows for configuration control of observations, associated scripts, and management of hardware and software limits and constraints, as well as tools for rapid data evaluation, and flexible re-planning in response to the unexpected. As examples of our test and analysis approach, we discuss how factors such as the ground test thermal environment are compensated in alignment. We describe how these innovative methods for test planning and execution and post-test analysis were instrumental in the verification program for the ISIM element, with enough information to allow the reader to consider these innovations and lessons learned in this successful effort in their future testing for other programs.
Effects of 3 Different Elastic Therapeutic Taping Methods on the Subacromial Joint Space.
Lyman, Katie J; Gange, Kara N; Hanson, Thomas A; Mellinger, Christopher D
2017-09-01
The purpose of this study was to examine the effects of 3 different elastic therapeutic taping methods on the subacromial joint space in healthy adults. Pre-/post-test laboratory study method was used in this study. Forty-eight healthy adults with no prior history of shoulder injury or surgery and no history of dominant shoulder pain in the past 6 months were enrolled in the study. Participants were placed into 3 groups (8 males and 8 females per group) on the basis of a consecutively assigned allocation design. A baseline measurement of the acromiohumeral distance (AHD) was taken by using diagnostic ultrasonography for every participant. On the basis of group assignment, participants were then taped according to the Kinesio Tape (Kinesio Tex Classic Tape) guidelines in one of 3 conditions: (1) taping of the supraspinatus from insertion to origin; (2) taping of the anterior and posterior deltoids from insertion to origin; and (3) a combination of both techniques. After a 5-minute wait period, the AHD was remeasured with the tape intervention in place, with each participant serving as his or her own control. Data analysis showed a statistically significant increase in AHD when using the taping technique over the anterior and posterior deltoids (Condition 2). The subacromial space increased in both males and females when the supraspinatus was taped from insertion to origin (Condition 1), but not at a statistically significant level. Condition 3, in which both taping techniques were used simultaneously, did not show an increase at a statistically significant level. The application of the Kinesio Tape from insertion to muscle origin of the supraspinatus or the anterior and posterior deltoid increased the subacromial joint space. Copyright © 2017. Published by Elsevier Inc.
Directory of Open Access Journals (Sweden)
Cristian PETCU
2010-01-01
Full Text Available This paper is part of the series of pre-standardization research aimed to analyze the existing methods of calculating the Buildings Energy Performance (PEC in view of their correction of completing. The entire research activity aims to experimentally validate the PEC Calculation Algorithm as well as the comparative application, on the support of several case studies focused on representative buildings of the stock of buildings in Romania, of the PEC calculation methodology for buildings equipped with occupied spaces heating systems. The targets of the report are the experimental testing of the calculation models so far known (NP 048-2000, Mc 001-2006, SR EN 13790:2009, on the support provided by the CE INCERC Bucharest experimental building, together with the complex calculation algorithms specific to the dynamic modeling, for the evaluation of the occupied spaces heat demand in the cold season, specific to the traditional buildings and to modern buildings equipped with solar radiation passive systems, of the ventilated solar space type. The schedule of the measurements performed in the 2008-2009 cold season is presented as well as the primary processing of the measured data and the experimental validation of the heat demand monthly calculation methods, on the support of CE INCERC Bucharest. The calculation error per heating season (153 days of measurements between the measured heat demand and the calculated one was of 0.61%, an exceptional value confirming the phenomenological nature of the INCERC method, NP 048-2006. The mathematical model specific to the hourly thermal balance is recurrent – decisional with alternating paces. The experimental validation of the theoretical model is based on the measurements performed on the CE INCERC Bucharest building, within a time lag of 57 days (06.01-04.03.2009. The measurements performed on the CE INCERC Bucharest building confirm the accuracy of the hourly calculation model by comparison to the values
Li, Xiangzhen; Liu, Shuai; Li, Zhi; Gong, Jiancun
2017-11-01
Data missing is a common phenomenon in the space environment measurements, which impacts or even blocks the following model-building procedures, predictions and posterior analysis. To fill these data gaps, an improved filling method based on iterative singular spectrum analysis is proposed. It first extracts a distribution array of the gaps and then fills the gaps with all known data. The distribution array is utilized to generate the test sets for cross validation. The embedding window length and principal components are determined by the discrete particle swarm optimization algorithm in a noncontinuous fashion. The effectiveness and adaptability of the filling method are proved by some tests done on solar wind data and geomagnetic indices from different solar activity years.
Single image super-resolution via an iterative reproducing kernel Hilbert space method.
Deng, Liang-Jian; Guo, Weihong; Huang, Ting-Zhu
2016-11-01
Image super-resolution, a process to enhance image resolution, has important applications in satellite imaging, high definition television, medical imaging, etc. Many existing approaches use multiple low-resolution images to recover one high-resolution image. In this paper, we present an iterative scheme to solve single image super-resolution problems. It recovers a high quality high-resolution image from solely one low-resolution image without using a training data set. We solve the problem from image intensity function estimation perspective and assume the image contains smooth and edge components. We model the smooth components of an image using a thin-plate reproducing kernel Hilbert space (RKHS) and the edges using approximated Heaviside functions. The proposed method is applied to image patches, aiming to reduce computation and storage. Visual and quantitative comparisons with some competitive approaches show the effectiveness of the proposed method.
Directory of Open Access Journals (Sweden)
Serhii Kovbasiuk
2017-04-01
Full Text Available One of the reasons for the decrease of efficiency in low-speed communication systems, satellite communication, which are based on nanoplatform is a high degree of operational planning centralisation. To overcome this problem the method which carries out the distribution of tasks of communications operational planning minimizing the exchange of information between spatially remote sites, and takes into account the computing performance of software and hardware was developed. The technique is based on the use of methods of structural and parametric synthesis, simulation and statistical analysis of the results. Its use allows to obtain the optimal structure of the automated system of operational planning in low-space communication system messaging evaluation of efficiency in terms of fixed communication of information load.
A hybrid method of estimating pulsating flow parameters in the space-time domain
Pałczyński, Tomasz
2017-05-01
This paper presents a method for estimating pulsating flow parameters in partially open pipes, such as pipelines, internal combustion engine inlets, exhaust pipes and piston compressors. The procedure is based on the method of characteristics, and employs a combination of measurements and simulations. An experimental test rig is described, which enables pressure, temperature and mass flow rate to be measured within a defined cross section. The second part of the paper discusses the main assumptions of a simulation algorithm elaborated in the Matlab/Simulink environment. The simulation results are shown as 3D plots in the space-time domain, and compared with proposed models of phenomena relating to wave propagation, boundary conditions, acoustics and fluid mechanics. The simulation results are finally compared with acoustic phenomena, with an emphasis on the identification of resonant frequencies.
Three-Dimensional Navier-Stokes Calculations Using the Modified Space-Time CESE Method
Chang, Chau-lyan
2007-01-01
The space-time conservation element solution element (CESE) method is modified to address the robustness issues of high-aspect-ratio, viscous, near-wall meshes. In this new approach, the dependent variable gradients are evaluated using element edges and the corresponding neighboring solution elements while keeping the original flux integration procedure intact. As such, the excellent flux conservation property is retained and the new edge-based gradients evaluation significantly improves the robustness for high-aspect ratio meshes frequently encountered in three-dimensional, Navier-Stokes calculations. The order of accuracy of the proposed method is demonstrated for oblique acoustic wave propagation, shock-wave interaction, and hypersonic flows over a blunt body. The confirmed second-order convergence along with the enhanced robustness in handling hypersonic blunt body flow calculations makes the proposed approach a very competitive CFD framework for 3D Navier-Stokes simulations.
Exploiting Stabilizers and Parallelism in State Space Generation with the Symmetry Method
DEFF Research Database (Denmark)
Lorentsen, Louise; Kristensen, Lars Michael
2001-01-01
The symmetry method is a main reduction paradigm for alleviating the state explosion problem. For large symmetry groups deciding whether two states are symmetric becomes time expensive due to the apparent high time complexity of the orbit problem. The contribution of this paper is to alleviate th...... the negative impact of the orbit problem by the specification of canonical representatives for equivalence classes of states in Coloured Petri Nets, and by giving algorithms exploiting stabilizers and parallelism for computing the condensed state space.......The symmetry method is a main reduction paradigm for alleviating the state explosion problem. For large symmetry groups deciding whether two states are symmetric becomes time expensive due to the apparent high time complexity of the orbit problem. The contribution of this paper is to alleviate...
Directory of Open Access Journals (Sweden)
JERFFSON LUCAS SANTOS
2016-01-01
Full Text Available The passion fruit (Passiflora cincinnata Mast. is a perennial and drought resistant species that represents a new alternative crop for small farmers in rainfed conditions. This study aimed to evaluate the vegetative and physiological development of passion fruit plants derived from two propagation methods and grown at varied planting spacing. The experiment was conducted from January to June of 2012, in the Universidade Estadual do Sudoeste da Bahia (State University from Southwestern Bahia, in Brazil. It was carried out in a randomized block design under a 2 x 3 factorial scheme, which consisted of two propagation methods (cutting and seeds and three planting spacing distances within a row (1.5; 3.0 and 4.0 m, however, at same distance between rows (3.0 m, with four replicates and four plants per plot. Cuttings and seeds were sampled from adult plants pre-selected in native areas from Vitória da Conquista - BA, Brazil. Growth (stem diameter and leaf area and physiological parameters (leaf chlorophyll content, leaf water potential before dawn, relative water content and leaf gas exchange were assessed on the 90th, 120th and 150th day after transplanting of seedlings into the field (DAT. Based on our results, we concluded that despite plants propagated via cuttings showed most favorable water status, vegetative growth and photosynthetic capacity were lower whether compared to plants obtained from seeds.
A METHOD FOR SELF-CALIBRATION IN SATELLITE WITH HIGH PRECISION OF SPACE LINEAR ARRAY CAMERA
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W. Liu
2016-06-01
Full Text Available At present, the on-orbit calibration of the geometric parameters of a space surveying camera is usually processed by data from a ground calibration field after capturing the images. The entire process is very complicated and lengthy and cannot monitor and calibrate the geometric parameters in real time. On the basis of a large number of on-orbit calibrations, we found that owing to the influence of many factors, e.g., weather, it is often difficult to capture images of the ground calibration field. Thus, regular calibration using field data cannot be ensured. This article proposes a real time self-calibration method for a space linear array camera on a satellite using the optical auto collimation principle. A collimating light source and small matrix array CCD devices are installed inside the load system of the satellite; these use the same light path as the linear array camera. We can extract the location changes of the cross marks in the matrix array CCD to determine the real-time variations in the focal length and angle parameters of the linear array camera. The on-orbit status of the camera is rapidly obtained using this method. On one hand, the camera’s change regulation can be mastered accurately and the camera’s attitude can be adjusted in a timely manner to ensure optimal photography; in contrast, self-calibration of the camera aboard the satellite can be realized quickly, which improves the efficiency and reliability of photogrammetric processing.
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Yasas Shri Nalaka JAYARATNE
2017-12-01
Full Text Available Purpose: The objective of this systematic review was to compare the antero-posterior, vertical and angular changes of maxillary incisors with conventional anchorage control techniques and mini-implant based space closure methods. Materials and Methods: The electronic databases Pubmed, Scopus, ISI Web of knowledge, Cochrane Library and Open Grey were searched for potentially eligible studies using a set of predetermined keywords. Full texts meeting the inclusion criteria as well as their references were manually searched. The primary outcome data (linear, angular, and vertical maxillary incisor changes and secondary outcome data (overbite changes, soft tissue changes, biomechanical factors, root resorption and treatment duration were extracted from the selected articles and entered into spreadsheets based on the type of anchorage used. The methodological quality of each study was assessed. Results: Six studies met the inclusion criteria. The amount of incisor retraction was greater with buccally placed mini-implants than conventional anchorage techniques. The incisor retraction with indirect anchorage from palatal mini-implants was less when compared with buccally placed mini-implants. Incisor intrusion occurred with buccal mini-implants, whereas extrusion was seen with conventional anchorage. Limited data on the biomechanical variables or adverse effects such as root resorption were reported in these studies. Conclusion: More RCT’s that take in to account relevant biomechanical variables and employ three-dimensional quantification of tooth movements are required to provide information on incisor changes during space closure.
A Gauss-Newton method for the integration of spatial normal fields in shape Space
Balzer, Jonathan
2011-08-09
We address the task of adjusting a surface to a vector field of desired surface normals in space. The described method is entirely geometric in the sense, that it does not depend on a particular parametrization of the surface in question. It amounts to solving a nonlinear least-squares problem in shape space. Previously, the corresponding minimization has been performed by gradient descent, which suffers from slow convergence and susceptibility to local minima. Newton-type methods, although significantly more robust and efficient, have not been attempted as they require second-order Hadamard differentials. These are difficult to compute for the problem of interest and in general fail to be positive-definite symmetric. We propose a novel approximation of the shape Hessian, which is not only rigorously justified but also leads to excellent numerical performance of the actual optimization. Moreover, a remarkable connection to Sobolev flows is exposed. Three other established algorithms from image and geometry processing turn out to be special cases of ours. Our numerical implementation founds on a fast finite-elements formulation on the minimizing sequence of triangulated shapes. A series of examples from a wide range of different applications is discussed to underline flexibility and efficiency of the approach. © 2011 Springer Science+Business Media, LLC.
International Nuclear Information System (INIS)
Rios, I.J.; Mayer, R.E.
2016-01-01
When proportional counters are employed in charge integration mode to determine the magnitude of a radiation pulse, so intense that individual detection events take place in a time too short to produce individual output pulses, mostly in pulsed neutron sources, the strong build-up of positive space charge reduces the electric multiplication factor of the proportional detector. Under such conditions the ensuing measurement underestimates the amount of radiation that interacted with the detector. If the geometric characteristics, the filling gas pressure and the voltage applied to that detector are known, it becomes possible to apply an analytical correction method to the measurement. In this article we present a method that allows to determine the absolute value of the detected radiation burst without the need to know the characteristics of the employed detectors. It is necessary to employ more than one detector, taking advantage of the Influence Method. The “Influence Method” is conceived for the absolute determination of a nuclear particle flux in the absence of known detector efficiency and without the need to register coincidences of any kind. This method exploits the influence of the presence of one detector in the count rate of another detector, when they are placed one behind the other and define statistical estimators for the absolute number of incident particles and for the efficiency (Rios and Mayer, 2015 [1,2]). Its practical implementation in the measurement of a moderated neutron flux arising from an isotopic neutron source was exemplified in (Rios and Mayer, 2016 [3]) and the extension for multiple detectors in (Rios and Mayer 2016 [4]). - Highlights: • Absolute determination of radiation burst. • Proportional counters space charge effect. • Radiation measurements on pulsed devices.
Zhang, Dai; Hao, Shiqi; Zhao, Qingsong; Zhao, Qi; Wang, Lei; Wan, Xiongfeng
2018-03-01
Existing wavefront reconstruction methods are usually low in resolution, restricted by structure characteristics of the Shack Hartmann wavefront sensor (SH WFS) and the deformable mirror (DM) in the adaptive optics (AO) system, thus, resulting in weak homodyne detection efficiency for free space optical (FSO) communication. In order to solve this problem, we firstly validate the feasibility of liquid crystal spatial light modulator (LC SLM) using in an AO system. Then, wavefront reconstruction method based on wavelet fractal interpolation is proposed after self-similarity analysis of wavefront distortion caused by atmospheric turbulence. Fast wavelet decomposition is operated to multiresolution analyze the wavefront phase spectrum, during which soft threshold denoising is carried out. The resolution of estimated wavefront phase is then improved by fractal interpolation. Finally, fast wavelet reconstruction is taken to recover wavefront phase. Simulation results reflect the superiority of our method in homodyne detection. Compared with minimum variance estimation (MVE) method based on interpolation techniques, the proposed method could obtain superior homodyne detection efficiency with lower operation complexity. Our research findings have theoretical significance in the design of coherent FSO communication system.
Space-Time Conservation Element and Solution Element Method Being Developed
Chang, Sin-Chung; Himansu, Ananda; Jorgenson, Philip C. E.; Loh, Ching-Yuen; Wang, Xiao-Yen; Yu, Sheng-Tao
1999-01-01
The engineering research and design requirements of today pose great computer-simulation challenges to engineers and scientists who are called on to analyze phenomena in continuum mechanics. The future will bring even more daunting challenges, when increasingly complex phenomena must be analyzed with increased accuracy. Traditionally used numerical simulation methods have evolved to their present state by repeated incremental extensions to broaden their scope. They are reaching the limits of their applicability and will need to be radically revised, at the very least, to meet future simulation challenges. At the NASA Lewis Research Center, researchers have been developing a new numerical framework for solving conservation laws in continuum mechanics, namely, the Space-Time Conservation Element and Solution Element Method, or the CE/SE method. This method has been built from fundamentals and is not a modification of any previously existing method. It has been designed with generality, simplicity, robustness, and accuracy as cornerstones. The CE/SE method has thus far been applied in the fields of computational fluid dynamics, computational aeroacoustics, and computational electromagnetics. Computer programs based on the CE/SE method have been developed for calculating flows in one, two, and three spatial dimensions. Results have been obtained for numerous problems and phenomena, including various shock-tube problems, ZND detonation waves, an implosion and explosion problem, shocks over a forward-facing step, a blast wave discharging from a nozzle, various acoustic waves, and shock/acoustic-wave interactions. The method can clearly resolve shock/acoustic-wave interactions, wherein the difference of the magnitude between the acoustic wave and shock could be up to six orders. In two-dimensional flows, the reflected shock is as crisp as the leading shock. CE/SE schemes are currently being used for advanced applications to jet and fan noise prediction and to chemically
A continuous scale-space method for the automated placement of spot heights on maps
Rocca, Luigi; Jenny, Bernhard; Puppo, Enrico
2017-12-01
Spot heights and soundings explicitly indicate terrain elevation on cartographic maps. Cartographers have developed design principles for the manual selection, placement, labeling, and generalization of spot height locations, but these processes are work-intensive and expensive. Finding an algorithmic criterion that matches the cartographers' judgment in ranking the significance of features on a terrain is a difficult endeavor. This article proposes a method for the automated selection of spot heights locations representing natural features such as peaks, saddles and depressions. A lifespan of critical points in a continuous scale-space model is employed as the main measure of the importance of features, and an algorithm and a data structure for its computation are described. We also introduce a method for the comparison of algorithmically computed spot height locations with manually produced reference compilations. The new method is compared with two known techniques from the literature. Results show spot height locations that are closer to reference spot heights produced manually by swisstopo cartographers, compared to previous techniques. The introduced method can be applied to elevation models for the creation of topographic and bathymetric maps. It also ranks the importance of extracted spot height locations, which allows for a variation in the size of symbols and labels according to the significance of represented features. The importance ranking could also be useful for adjusting spot height density of zoomable maps in real time.
Optimal q-homotopy analysis method for time-space fractional gas dynamics equation
Saad, K. M.; AL-Shareef, E. H.; Mohamed, Mohamed S.; Yang, Xiao-Jun
2017-01-01
It is well known that the homotopy analysis method is one of the most efficient methods for obtaining analytical or approximate semi-analytical solutions of both linear and non-linear partial differential equations. A more general form of HAM is introduced in this paper, which is called Optimal q-Homotopy Analysis Method (Oq-HAM). It has better convergence properties as compared with the usual HAM, due to the presence of fraction factor associated with the solution. The convergence of q-HAM is studied in details elsewhere (M.A. El-Tawil, Int. J. Contemp. Math. Sci. 8, 481 (2013)). Oq-HAM is applied to the non-linear homogeneous and non-homogeneous time and space fractional gas dynamics equations with initial condition. An optimal convergence region is determined through the residual error. By minimizing the square residual error, the optimal convergence control parameters can be obtained. The accuracy and efficiency of the proposed method are verified by comparison with the exact solution of the fractional gas dynamics equation. Also, it is shown that the Oq-HAM for the fractional gas dynamics equation is equivalent to the exact solution. We obtain graphical representations of the solutions using MATHEMATICA.
Kijvikai, Kittinut; Laguna, M. Pilar; de la Rosette, Jean
2006-01-01
We describe our technique for large renal vein control in the limited dissected space during laparoscopic nephrectomy. This technique is a simple, inexpensive and reliable method, especially for large and short renal vein ligation
Discrete- vs. Continuous-Time Modeling of Unequally Spaced Experience Sampling Method Data
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Silvia de Haan-Rietdijk
2017-10-01
Full Text Available The Experience Sampling Method is a common approach in psychological research for collecting intensive longitudinal data with high ecological validity. One characteristic of ESM data is that it is often unequally spaced, because the measurement intervals within a day are deliberately varied, and measurement continues over several days. This poses a problem for discrete-time (DT modeling approaches, which are based on the assumption that all measurements are equally spaced. Nevertheless, DT approaches such as (vector autoregressive modeling are often used to analyze ESM data, for instance in the context of affective dynamics research. There are equivalent continuous-time (CT models, but they are more difficult to implement. In this paper we take a pragmatic approach and evaluate the practical relevance of the violated model assumption in DT AR(1 and VAR(1 models, for the N = 1 case. We use simulated data under an ESM measurement design to investigate the bias in the parameters of interest under four different model implementations, ranging from the true CT model that accounts for all the exact measurement times, to the crudest possible DT model implementation, where even the nighttime is treated as a regular interval. An analysis of empirical affect data illustrates how the differences between DT and CT modeling can play out in practice. We find that the size and the direction of the bias in DT (VAR models for unequally spaced ESM data depend quite strongly on the true parameter in addition to data characteristics. Our recommendation is to use CT modeling whenever possible, especially now that new software implementations have become available.
Saedpanah, Fardin
2012-01-01
An integro-differential equation of hyperbolic type, with mixed boundary conditions, is considered. A continuous space-time finite element method of degree one is formulated. A posteriori error representations based on space-time cells is presented such that it can be used for adaptive strategies based on dual weighted residual methods. A posteriori error estimates based on weighted global projections and local projections are also proved.
Hybrid methods for a finite family of G-nonexpansive mappings in Hilbert spaces endowed with graphs
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Raweerote Suparatulatorn
2017-08-01
Full Text Available In this paper, we prove a strong convergence theorem for two different hybrid methods by using CQ method for a finite family of G-nonexpansive mappings in a Hilbert space. We give an example and numerical results for supporting our main results and compare the rate of convergence of the two iterative methods.
Focus determination for the James Webb Space Telescope Science Instruments: A Survey of Methods
Davila, Pamela S.; Bolcar, Matthew R.; Boss, B.; Dean, B.; Hapogian, J.; Howard, J.; Unger, B.; Wilson, M.
2006-01-01
The James Webb Space Telescope (JWST) is a segmented deployable telescope that will require on-orbit alignment using the Near Infrared Camera as a wavefront sensor. The telescope will be aligned by adjusting seven degrees of freedom on each of 18 primary mirror segments and five degrees of freedom on the secondary mirror to optimize the performance of the telescope and camera at a wavelength of 2 microns. With the completion of these adjustments, the telescope focus is set and the optical performance of each of the other science instruments should then be optimal without making further telescope focus adjustments for each individual instrument. This alignment approach requires confocality of the instruments after integration and alignment to the composite metering structure, which will be verified during instrument level testing at Goddard Space Flight Center with a telescope optical simulator. In this paper, we present the results from a study of several analytical approaches to determine the focus for each instrument. The goal of the study is to compare the accuracies obtained for each method, and to select the most feasible for use during optical testing.
Jayaratne, Yasas Shri Nalaka; Uribe, Flavio; Janakiraman, Nandakumar
2017-01-01
The objective of this systematic review was to compare the antero-posterior, vertical and angular changes of maxillary incisors with conventional anchorage control techniques and mini-implant based space closure methods. The electronic databases Pubmed, Scopus, ISI Web of knowledge, Cochrane Library and Open Grey were searched for potentially eligible studies using a set of predetermined keywords. Full texts meeting the inclusion criteria as well as their references were manually searched. The primary outcome data (linear, angular, and vertical maxillary incisor changes) and secondary outcome data (overbite changes, soft tissue changes, biomechanical factors, root resorption and treatment duration) were extracted from the selected articles and entered into spreadsheets based on the type of anchorage used. The methodological quality of each study was assessed. Six studies met the inclusion criteria. The amount of incisor retraction was greater with buccally placed mini-implants than conventional anchorage techniques. The incisor retraction with indirect anchorage from palatal mini-implants was less when compared with buccally placed mini-implants. Incisor intrusion occurred with buccal mini-implants, whereas extrusion was seen with conventional anchorage. Limited data on the biomechanical variables or adverse effects such as root resorption were reported in these studies. More RCT's that take in to account relevant biomechanical variables and employ three-dimensional quantification of tooth movements are required to provide information on incisor changes during space closure.
Method and device for fabricating dispersion fuel comprising fission product collection spaces
Shaber, Eric L; Fielding, Randall S
2015-05-05
A method of fabricating a nuclear fuel comprising a fissile material, one or more hollow microballoons, a phenolic resin, and metal matrix. The fissile material, phenolic resin and the one or more hollow microballoons are combined. The combined fissile material, phenolic resin and the hollow microballoons are heated sufficiently to form at least some fissile material carbides creating a nuclear fuel particle. The resulting nuclear fuel particle comprises one or more fission product collection spaces. In a preferred embodiment, the fissile material, phenolic resin and the one or more hollow microballoons are combined by forming the fissile material into microspheres. The fissile material microspheres are then overcoated with the phenolic resin and microballoon. In another preferred embodiment, the fissile material, phenolic resin and the one or more hollow microballoons are combined by overcoating the microballoon with the fissile material, and phenolic resin.
Becker, F.; Seguin, B.
Climate being the result of many interconnected processes, it can hardly be understood without models which describe these various processes as quantitatively as possible and define the parameters which are relevant for climate studies. Among those, surface processes and therefore surface parameters are now recognized to be of great importance. Some examples are discussed in the first part, showing the great interest to measure the relevant parameters on a multi-year basis, over large areas with sufficiently dense array and on a stable basis, in order to monitor climate changes or to study the impact on climate of the modifications of some relevant parameters which are analysed. Since space observations from satellites fulfil these requirements, it is clear that they will become very soon a fundamental tool for climate studies. Unfortunately, as it is discussed in the second part, satellites do measure only spectral radiances at the top of the atmosphere and the determination of the relevant surface parameters (or fluxes) from these radiances still raises many problems which have to be solved, although many progresses have already been made. The aim of this paper is therefore to review and discuss these problems and the various ways they have been tackled until now. The first part is devoted to an overview of what needs to be measured and why, while the existing methods for determining the most important surface parameters from space observations are presented in the second part where a particular attention is given to the theoretical and experimental validations of these methods, their limits and the problems still to be solved.
Potential Functions of Al2 by the Relativistic Fock-Space Coupled Cluster Method
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Uzi Kaldor
2002-05-01
Full Text Available Abstract: Potential functions of the ground and low excited states of Al2 are calculated by the relativistic Fock-space coupled cluster method in the framework of the projected Dirac-Coulomb Hamiltonian. A moderate-size basis [16s11p3d3f/6s6p3d2f] is used. 3ÃŽÂ u is confirmed as the ground state of the system. Its spin orbit splittings are reproduced well, with the ÃŽÂ› = 1, 2 states lying 32.5 and 66.1 cmÃ¢ÂˆÂ’1, respectively, above the ÃŽÂ› = 0 minimum (experimental values are 30.4 and 63.4 cmÃ¢ÂˆÂ’1. The bond is somewhat too weak, with De 0.14 eV below experiment, Re too high by 0.08 Ã‹ÂšA, and ÃÂ‰e 21 cmÃ¢ÂˆÂ’1 too low. It is speculated that the better agreement obtained in earlier calculations may be due to neglect of basis set superposition errors. The description of bonding in the molecule may be improved by the use of a better basis and the inclusion of more correlation by the intermediate Hamiltonian coupled cluster method, which makes it possible to handle larger P spaces and extend the potential functions to the whole range of internuclear separations.
Quick acquisition and recognition method for the beacon in deep space optical communications.
Wang, Qiang; Liu, Yuefei; Ma, Jing; Tan, Liying; Yu, Siyuan; Li, Changjiang
2016-12-01
In deep space optical communications, it is very difficult to acquire the beacon given the long communication distance. Acquisition efficiency is essential for establishing and holding the optical communication link. Here we proposed a quick acquisition and recognition method for the beacon in deep optical communications based on the characteristics of the deep optical link. To identify the beacon from the background light efficiently, we utilized the maximum similarity between the collecting image and the reference image for accurate recognition and acquisition of the beacon in the area of uncertainty. First, the collecting image and the reference image were processed by Fourier-Mellin. Second, image sampling and image matching were applied for the accurate positioning of the beacon. Finally, the field programmable gate array (FPGA)-based system was used to verify and realize this method. The experimental results showed that the acquisition time for the beacon was as fast as 8.1s. Future application of this method in the system design of deep optical communication will be beneficial.
Image enhancement methods for turbulence mitigation and the influence of different color spaces
Huebner, Claudia S.
2015-10-01
In mid- to long-range horizontal imaging applications it is quite often atmospheric turbulence which limits the performance of an electro-optical system rather than the design and quality of the system itself. Even weak or moderate turbulence conditions can suffice to cause significant image degradation, the predominant effects being image dancing and blurring. To mitigate these effects many different methods have been proposed, most of which use either a hardware approach, such as adaptive optics, or a software approach. A great number of these methods are highly specialized with regard to input data, e.g. aiming exclusively at very short exposure images or at infrared data. So far, only a very limited number of these methods are concerned specifically with the restoration of RGB colour video. Beside motion compensation and deblurring, contrast enhancement plays a vital part in many turbulence mitigation schemes. While most contrast enhancement techniques, such as Contrast Limited Adaptive Histogram Equalization (CLAHE) work quite well on monochrome data or single colour frames, they tend to amplify noise in a colour video stream disproportionately, especially in scenes with low contrast. Therefore, in this paper the impact of different colour spaces (RGB, LAB, HSV) on the application of such typical image enhancement techniques is discussed and evaluated with regard to suppressing temporal noise as well as to their suitability for use in software-based turbulence mitigation algorithms.
Bostic, Susan W.; Fulton, Robert E.
1987-01-01
Eigenvalue analyses of complex structures is a computationally intensive task which can benefit significantly from new and impending parallel computers. This study reports on a parallel computer implementation of the Lanczos method for free vibration analysis. The approach used here subdivides the major Lanczos calculation tasks into subtasks and introduces parallelism down to the subtask levels such as matrix decomposition and forward/backward substitution. The method was implemented on a commercial parallel computer and results were obtained for a long flexible space structure. While parallel computing efficiency is problem and computer dependent, the efficiency for the Lanczos method was good for a moderate number of processors for the test problem. The greatest reduction in time was realized for the decomposition of the stiffness matrix, a calculation which took 70 percent of the time in the sequential program and which took 25 percent of the time on eight processors. For a sample calculation of the twenty lowest frequencies of a 486 degree of freedom problem, the total sequential computing time was reduced by almost a factor of ten using 16 processors.
Fabrication of T-SOFC via Freeze Cast Methods for Space and Portable Applications, Phase I
National Aeronautics and Space Administration — As NASA space missions become longer in duration the need for high efficiency power generator sets that can operate on NASA logistical fuel become critical....
A comparison of the super-CI and the Newton-Raphson scheme in the complete active space SCF method
International Nuclear Information System (INIS)
Siegbahn, P.; Heiberg, A.; Roos, B.; Levy, B.
1980-01-01
A density matrix formulation is presented of the super-CI and Newton-Raphson methods in complete active space SCF (CASSCF) calculations. The CASSCF method is a special form of the MC-SCF method, where the CI wave function is assumed to be complete in a subset of the orbital space (the active space), leaving the remaining orbitals doubly occupied in all configurations. Explicit formulas are given for all matrix elements in the super-CI method and the first and second derivatives in the Newton-Raphson formulation. The similarities between the two methods are pointed out and the differences in the detailed formulations are discussed. Especially interesting is the fact, that while the second derivatives can be expressed in terms of first and second order density matrices, the matrix elements between the super-CI states involve also the third order density matrix in some cases. (Auth.)
Application of RBS and XFA methods to investigation of polyimide films from Mir space station
International Nuclear Information System (INIS)
Zatekin, V.V.; Kulikauskas, V.S.; Novikov, L.S.; Petukhov, V.P.; Chernik, V.N.; Chernykh, P.N.; Bakhvalov, Yu.O.; Aleksandrov, N.G.; Smirnova, T.N.
2008-01-01
Elemental composition of contaminations of polyimide films were studied by RBS and XFA. The films were exposed to space on orbital space station Mir during in-flight experiment KOMPLAST. Deposit dominating element is shown to be silicon in accordance with another space crafts measurements [ru
International Nuclear Information System (INIS)
Ageev, S M
2007-01-01
The Noebeling space N k 2k+1 , a k-dimensional analogue of the Hilbert space, is considered; this is a topologically complete separable (that is, Polish) k-dimensional absolute extensor in dimension k (that is, AE(k)) and a strongly k-universal space. The conjecture that the above-listed properties characterize the Noebeling space N k 2k+1 in an arbitrary finite dimension k is proved. In the first part of the paper a full axiom system of the Noebeling spaces is presented and the problem of the improvement of a partition connectivity is solved on its basis. Bibliography: 29 titles.
A Space-Frequency Data Compression Method for Spatially Dense Laser Doppler Vibrometer Measurements
Directory of Open Access Journals (Sweden)
José Roberto de França Arruda
1996-01-01
Full Text Available When spatially dense mobility shapes are measured with scanning laser Doppler vibrometers, it is often impractical to use phase-separation modal parameter estimation methods due to the excessive number of highly coupled modes and to the prohibitive computational cost of processing huge amounts of data. To deal with this problem, a data compression method using Chebychev polynomial approximation in the frequency domain and two-dimensional discrete Fourier series approximation in the spatial domain, is proposed in this article. The proposed space-frequency regressive approach was implemented and verified using a numerical simulation of a free-free-free-free suspended rectangular aluminum plate. To make the simulation more realistic, the mobility shapes were synthesized by modal superposition using mode shapes obtained experimentally with a scanning laser Doppler vibrometer. A reduced and smoothed model, which takes advantage of the sinusoidal spatial pattern of structural mobility shapes and the polynomial frequency-domain pattern of the mobility shapes, is obtained. From the reduced model, smoothed curves with any desired frequency and spatial resolution can he produced whenever necessary. The procedure can he used either to generate nonmodal models or to compress the measured data prior to modal parameter extraction.
Energy expenditure in space flight (doubly labelled water method) (8-IML-1)
Parsons, Howard G.
1992-01-01
The objective of the Energy Expenditure in Space Flight (ESS) experiment is to demonstrate and evaluate the doubly labeled water method of measuring the energy expended by crew members during approximately 7 days in microgravity. The doubly labeled water technique determines carbon dioxide production which is then used to calculate energy expenditure. The method relies on the equilibrium between oxygen in respiratory carbon dioxide and oxygen in body water. Because of this equilibrium, the kinetic of water turnover and respiration are interdependent. Under normal conditions, man contains small but significant amounts of deuterium and oxygen 18. Deuterium is eliminated from the body as water while oxygen 18 is eliminated as water and carbon dioxide. The difference in the turnover rates in the two isotopes is proportional to the carbon dioxide production. Deliberately enriching the total body water with both of these isotopes allows the isotope turnovers to be accurately measured in urine, plasma, or saliva samples. The samples are taken to the laboratory for analysis using an ion-ratio spectrometer.
Energy Technology Data Exchange (ETDEWEB)
Hollerbach, K.; Van Vorhis, R.L. [Lawrence Livermore National Lab., CA (United States); Hollister, A. [Louisiana State Univ., Shreveport, LA (United States)
1996-03-01
Wrist posture and rapid wrist movements are risk factors for work related musculoskeletal disorders. Measurement studies frequently involve optoelectronic methods in which markers are placed on the subject`s hand and wrist and the trajectories of the markers are tracked in three dimensional space. A goal of wrist posture measurements is to quantitatively establish wrist posture orientation. Accuracy and fidelity of the measurement data with respect to kinematic mechanisms are essential in wrist motion studies. Fidelity with the physical kinematic mechanism can be limited by the choice of kinematic modeling techniques and the representation of motion. Frequently, ergonomic studies involving wrist kinematics make use of two dimensional measurement and analysis techniques. Two dimensional measurement of human joint motion involves the analysis of three dimensional displacements in an obersver selected measurement plane. Accurate marker placement and alignment of joint motion plane with the observer plane are difficult. In nature, joint axes can exist at any orientation and location relative to an arbitrarily chosen global reference frame. An arbitrary axis is any axis that is not coincident with a reference coordinate. We calculate the errors that result from measuring joint motion about an arbitrary axis using two dimensional methods.
Exploring context and content links in social media: a latent space method.
Qi, Guo-Jun; Aggarwal, Charu; Tian, Qi; Ji, Heng; Huang, Thomas S
2012-05-01
Social media networks contain both content and context-specific information. Most existing methods work with either of the two for the purpose of multimedia mining and retrieval. In reality, both content and context information are rich sources of information for mining, and the full power of mining and processing algorithms can be realized only with the use of a combination of the two. This paper proposes a new algorithm which mines both context and content links in social media networks to discover the underlying latent semantic space. This mapping of the multimedia objects into latent feature vectors enables the use of any off-the-shelf multimedia retrieval algorithms. Compared to the state-of-the-art latent methods in multimedia analysis, this algorithm effectively solves the problem of sparse context links by mining the geometric structure underlying the content links between multimedia objects. Specifically for multimedia annotation, we show that an effective algorithm can be developed to directly construct annotation models by simultaneously leveraging both context and content information based on latent structure between correlated semantic concepts. We conduct experiments on the Flickr data set, which contains user tags linked with images. We illustrate the advantages of our approach over the state-of-the-art multimedia retrieval techniques.
Papaya Tree Detection with UAV Images Using a GPU-Accelerated Scale-Space Filtering Method
Directory of Open Access Journals (Sweden)
Hao Jiang
2017-07-01
Full Text Available The use of unmanned aerial vehicles (UAV can allow individual tree detection for forest inventories in a cost-effective way. The scale-space filtering (SSF algorithm is commonly used and has the capability of detecting trees of different crown sizes. In this study, we made two improvements with regard to the existing method and implementations. First, we incorporated SSF with a Lab color transformation to reduce over-detection problems associated with the original luminance image. Second, we ported four of the most time-consuming processes to the graphics processing unit (GPU to improve computational efficiency. The proposed method was implemented using PyCUDA, which enabled access to NVIDIA’s compute unified device architecture (CUDA through high-level scripting of the Python language. Our experiments were conducted using two images captured by the DJI Phantom 3 Professional and a most recent NVIDIA GPU GTX1080. The resulting accuracy was high, with an F-measure larger than 0.94. The speedup achieved by our parallel implementation was 44.77 and 28.54 for the first and second test image, respectively. For each 4000 × 3000 image, the total runtime was less than 1 s, which was sufficient for real-time performance and interactive application.
Directory of Open Access Journals (Sweden)
Haiwen Li
2018-01-01
Full Text Available The estimation speed of positioning parameters determines the effectiveness of the positioning system. The time of arrival (TOA and direction of arrival (DOA parameters can be estimated by the space-time two-dimensional multiple signal classification (2D-MUSIC algorithm for array antenna. However, this algorithm needs much time to complete the two-dimensional pseudo spectral peak search, which makes it difficult to apply in practice. Aiming at solving this problem, a fast estimation method of space-time two-dimensional positioning parameters based on Hadamard product is proposed in orthogonal frequency division multiplexing (OFDM system, and the Cramer-Rao bound (CRB is also presented. Firstly, according to the channel frequency domain response vector of each array, the channel frequency domain estimation vector is constructed using the Hadamard product form containing location information. Then, the autocorrelation matrix of the channel response vector for the extended array element in frequency domain and the noise subspace are calculated successively. Finally, by combining the closed-form solution and parameter pairing, the fast joint estimation for time delay and arrival direction is accomplished. The theoretical analysis and simulation results show that the proposed algorithm can significantly reduce the computational complexity and guarantee that the estimation accuracy is not only better than estimating signal parameters via rotational invariance techniques (ESPRIT algorithm and 2D matrix pencil (MP algorithm but also close to 2D-MUSIC algorithm. Moreover, the proposed algorithm also has certain adaptability to multipath environment and effectively improves the ability of fast acquisition of location parameters.
Optimal control for wind turbine system via state-space method
Shanoob, Mudhafar L.
Renewable energy is becoming a fascinating research interest in future energy production because it is green and does not pollute nature. Wind energy is an excellent example of renewable resources that are evolving. Throughout the history of humanity, wind energy has been used. In ancient time, it was used to grind seeds, sailing etc. Nowadays, wind energy has been used to generate electrical power. Researchers have done a lot of research about using a wind source to generate electricity. As wind flow is not reliable, there is a challenge to get stable electricity out of this varying wind. This problem leads to the use of different control methods and the optimization of these methods to get a stable and reliable electrical energy. In this research, a wind turbine system is considered to study the transient and the steady-state stability; consisting of the aerodynamic system, drive train and generator. The Doubly Feed Induction Generator (DFIG) type generator is used in this thesis. The wind turbine system is connected to power system network. The grid is an infinite bus bar connected to a short transmission line and transformer. The generator is attached to the grid from the stator side. State-space method is used to model the wind turbine parts. The system is modeled and controlled using MATLAB/Simulation software. First, the current-mode control method (PVdq) with (PI) regulator is operated as a reference to find how the system reacts to an unexpected disturbance on the grid side or turbine side. The controller is operated with three scenarios of disruption: Disturbance-mechanical torque input, Step disturbance in the electrical torque reference and Fault Ride-through. In the simulation results, the time response and the transient stability of the system is a product of the disturbances that take a long time to settle. So, for this reason, Linear Quadratic Regulation (LQR) optimal control is utilized to solve this problem. The LQR method is designed based on
Gene flow analysis method, the D-statistic, is robust in a wide parameter space.
Zheng, Yichen; Janke, Axel
2018-01-08
We evaluated the sensitivity of the D-statistic, a parsimony-like method widely used to detect gene flow between closely related species. This method has been applied to a variety of taxa with a wide range of divergence times. However, its parameter space and thus its applicability to a wide taxonomic range has not been systematically studied. Divergence time, population size, time of gene flow, distance of outgroup and number of loci were examined in a sensitivity analysis. The sensitivity study shows that the primary determinant of the D-statistic is the relative population size, i.e. the population size scaled by the number of generations since divergence. This is consistent with the fact that the main confounding factor in gene flow detection is incomplete lineage sorting by diluting the signal. The sensitivity of the D-statistic is also affected by the direction of gene flow, size and number of loci. In addition, we examined the ability of the f-statistics, [Formula: see text] and [Formula: see text], to estimate the fraction of a genome affected by gene flow; while these statistics are difficult to implement to practical questions in biology due to lack of knowledge of when the gene flow happened, they can be used to compare datasets with identical or similar demographic background. The D-statistic, as a method to detect gene flow, is robust against a wide range of genetic distances (divergence times) but it is sensitive to population size. The D-statistic should only be applied with critical reservation to taxa where population sizes are large relative to branch lengths in generations.
Raslan, K. R.; EL-Danaf, Talaat S.; Ali, Khalid K.
2017-07-01
In the present paper, we established a traveling wave solution by using modified Kudryashov method for the space-time fractional nonlinear partial differential equations. The method is used to obtain the exact solutions for different types of the space-time fractional nonlinear partial differential equations such as, the space-time fractional coupled equal width wave equation (CEWE) and the space-time fractional coupled modified equal width wave equation (CMEW), which are the important soliton equations. Both equations are reduced to ordinary differential equations by the use of fractional complex transform and properties of modified Riemann-Liouville derivative. We plot the exact solutions for these equations at different time levels.
International Nuclear Information System (INIS)
Raslan, K. R.; Ali, Khalid K.; EL-Danaf, Talaat S.
2017-01-01
In the present paper, we established a traveling wave solution by using modified Kudryashov method for the space-time fractional nonlinear partial differential equations. The method is used to obtain the exact solutions for different types of the space-time fractional nonlinear partial differential equations such as, the space-time fractional coupled equal width wave equation (CEWE) and the space-time fractional coupled modified equal width wave equation (CMEW), which are the important soliton equations. Both equations are reduced to ordinary differential equations by the use of fractional complex transform and properties of modified Riemann–Liouville derivative. We plot the exact solutions for these equations at different time levels. (paper)
Surian, Didi; Dunn, Adam G; Orenstein, Liat; Bashir, Rabia; Coiera, Enrico; Bourgeois, Florence T
2018-02-01
Clinical trial registries can be used to monitor the production of trial evidence and signal when systematic reviews become out of date. However, this use has been limited to date due to the extensive manual review required to search for and screen relevant trial registrations. Our aim was to evaluate a new method that could partially automate the identification of trial registrations that may be relevant for systematic review updates. We identified 179 systematic reviews of drug interventions for type 2 diabetes, which included 537 clinical trials that had registrations in ClinicalTrials.gov. Text from the trial registrations were used as features directly, or transformed using Latent Dirichlet Allocation (LDA) or Principal Component Analysis (PCA). We tested a novel matrix factorisation approach that uses a shared latent space to learn how to rank relevant trial registrations for each systematic review, comparing the performance to document similarity to rank relevant trial registrations. The two approaches were tested on a holdout set of the newest trials from the set of type 2 diabetes systematic reviews and an unseen set of 141 clinical trial registrations from 17 updated systematic reviews published in the Cochrane Database of Systematic Reviews. The performance was measured by the number of relevant registrations found after examining 100 candidates (recall@100) and the median rank of relevant registrations in the ranked candidate lists. The matrix factorisation approach outperformed the document similarity approach with a median rank of 59 (of 128,392 candidate registrations in ClinicalTrials.gov) and recall@100 of 60.9% using LDA feature representation, compared to a median rank of 138 and recall@100 of 42.8% in the document similarity baseline. In the second set of systematic reviews and their updates, the highest performing approach used document similarity and gave a median rank of 67 (recall@100 of 62.9%). A shared latent space matrix factorisation
Singular solutions to the Seiberg-Witten and Freund equations on flat space from an iterative method
International Nuclear Information System (INIS)
Mosna, Ricardo A.
2006-01-01
Although it is well known that the Seiberg-Witten equations do not admit nontrivial L 2 solutions in flat space, singular solutions to them have been previously exhibited--either in R 3 or in the dimensionally reduced spaces R 2 and R 1 --which have physical interest. In this work, we employ an extension of the Hopf fibration to obtain an iterative procedure to generate particular singular solutions to the Seiberg-Witten and Freund equations on flat space. Examples of solutions obtained by such method are presented and briefly discussed
International Nuclear Information System (INIS)
Holmes-siedle, A.; Freeman, R.
1978-04-01
Space radiation effects in electronic subsystems are discussed. Useful data from a wide range of sources are presented and methods which have been newly developed to provide engineering solutions to the problem of degradation of devices in space are described. The new developments include a simple model for analyzing space-charge buildup in MOS devices, a ranking scheme for CMOS - LSI circuits and improved dose transmission curves and tradeoff curves for spacecraft life against shield weight. A complete analysis of a piece of spacecraft equipment is given. Recommendations for future progress in hardness engineering are made
Osetrin, Evgeny; Osetrin, Konstantin
2017-11-01
We consider space-time models with pure radiation, which admit integration of the eikonal equation by the method of separation of variables. For all types of these models, the equations of the energy-momentum conservation law are integrated. The resulting form of metric, energy density, and wave vectors of radiation as functions of metric for all types of spaces under consideration is presented. The solutions obtained can be used for any metric theories of gravitation.
About One Approach to Determine the Weights of the State Space Method
Directory of Open Access Journals (Sweden)
I. K. Romanova
2015-01-01
Full Text Available The article studies methods of determining weight coefficients, also called coefficients of criteria importance in multiobjective optimization (MOO. It is assumed that these coefficients indicate a degree of individual criteria influence on the final selection (final or summary assessment: the more is coefficient, the greater is contribution of its corresponding criterion.Today in the framework of modern information systems to support decision making for various purposes a number of methods for determining relative importance of criteria has been developed. Among those methods we can distinguish a utility method, method of weighted power average; weighted median; method of matching clustered rankings, method of paired comparison of importance, etc.However, it should be noted that different techniques available for calculating weights does not eliminate the main problem of multicriteria optimization namely, the inconsistency of individual criteria. The basis for solving multicriteria problems is a fundamental principle of multi-criteria selection i.e. Edgeworth - Pareto principle.Despite a large number of methods to determine the weights, the task remains relevant not only for reasons of evaluations subjectivity, but also because of the mathematical aspects. Today, recognized is the fact that, for example, such a popular method as linear convolution of private criteria, essentially, represents one of the heuristic approaches and, applying it, you can have got not the best final choice. Carlin lemma reflects the limits of the method application.The aim of this work is to offer one of the methods to calculate the weights applied to the problem of dynamic system optimization, the quality of which is determined by the criterion of a special type, namely integral quadratic quality criterion. The main challenge relates to the method of state space, which in the literature also is called the method of analytical design of optimal controllers.Despite the
Koohsari, Mohammad Javad; Mavoa, Suzanne; Villanueva, Karen; Sugiyama, Takemi; Badland, Hannah; Kaczynski, Andrew T; Owen, Neville; Giles-Corti, Billie
2015-05-01
Public open spaces such as parks and green spaces are key built environment elements within neighbourhoods for encouraging a variety of physical activity behaviours. Over the past decade, there has been a burgeoning number of active living research studies examining the influence of public open space on physical activity. However, the evidence shows mixed associations between different aspects of public open space (e.g., proximity, size, quality) and physical activity. These inconsistencies hinder the development of specific evidence-based guidelines for urban designers and policy-makers for (re)designing public open space to encourage physical activity. This paper aims to move this research agenda forward, by identifying key conceptual and methodological issues that may contribute to inconsistencies in research examining relations between public open space and physical activity. Copyright © 2015 Elsevier Ltd. All rights reserved.
Huang, Panfeng; Xu, Xiudong; Meng, Zhongjie
2014-01-01
The tethered space robot (TSR) is a new concept of space robot which consists of a robot platform, space tether and operation robot. This paper presents a multi-objective optimal trajectory planning and a coordinated tracking control scheme for TSR based on velocity impulse in the approaching phase. Both total velocity impulse and flight time are included in this optimization. The non-dominated sorting genetic algorithm is employed to obtain the optimal trajectory Pareto solution using the TS...
Fourier spectral methods for fractional-in-space reaction-diffusion equations
Bueno-Orovio, Alfonso
2014-04-01
© 2014, Springer Science+Business Media Dordrecht. Fractional differential equations are becoming increasingly used as a powerful modelling approach for understanding the many aspects of nonlocality and spatial heterogeneity. However, the numerical approximation of these models is demanding and imposes a number of computational constraints. In this paper, we introduce Fourier spectral methods as an attractive and easy-to-code alternative for the integration of fractional-in-space reaction-diffusion equations described by the fractional Laplacian in bounded rectangular domains of ℝ. The main advantages of the proposed schemes is that they yield a fully diagonal representation of the fractional operator, with increased accuracy and efficiency when compared to low-order counterparts, and a completely straightforward extension to two and three spatial dimensions. Our approach is illustrated by solving several problems of practical interest, including the fractional Allen–Cahn, FitzHugh–Nagumo and Gray–Scott models, together with an analysis of the properties of these systems in terms of the fractional power of the underlying Laplacian operator.
A two-level space-time color-coding method for 3D measurements using structured light
International Nuclear Information System (INIS)
Xue, Qi; Wang, Zhao; Huang, Junhui; Gao, Jianmin; Qi, Zhaoshuai
2015-01-01
Color-coding methods have significantly improved the measurement efficiency of structured light systems. However, some problems, such as color crosstalk and chromatic aberration, decrease the measurement accuracy of the system. A two-level space-time color-coding method is thus proposed in this paper. The method, which includes a space-code level and a time-code level, is shown to be reliable and efficient. The influence of chromatic aberration is completely mitigated when using this method. Additionally, a self-adaptive windowed Fourier transform is used to eliminate all color crosstalk components. Theoretical analyses and experiments have shown that the proposed coding method solves the problems of color crosstalk and chromatic aberration effectively. Additionally, the method guarantees high measurement accuracy which is very close to the measurement accuracy using monochromatic coded patterns. (paper)
A new cyber security risk evaluation method for oil and gas SCADA based on factor state space
International Nuclear Information System (INIS)
Yang, Li; Cao, Xiedong; Li, Jie
2016-01-01
Based on comprehensive analysis of the structure and the potential safety problem of oil and gas SCADA(Supervisor control and data acquisition) network, aiming at the shortcomings of traditional evaluation methods, combining factor state space and fuzzy comprehensive evaluation method, a new network security risk evaluation method of oil and gas SCADA is proposed. First of all, formal description of factor state space and its complete mathematical definition were presented; secondly, factor fuzzy evaluation steps were discussed; then, using analytic hierarchy method, evaluation index system for oil and gas SCADA system was established, the index weights of all factors were determined by two-two comparisons; structure design of three layers in reasoning machine was completed. Experiments and tests show that the proposed method is accurate, reliable and practical. Research results provide the template and the new method for the other industries.
Trembach, Vera
2014-01-01
Space is an introduction to the mysteries of the Universe. Included are Task Cards for independent learning, Journal Word Cards for creative writing, and Hands-On Activities for reinforcing skills in Math and Language Arts. Space is a perfect introduction to further research of the Solar System.
Solving the Poisson partial differential equation using vector space projection methods
Marendic, Boris
This research presents a new approach at solving the Poisson partial differential equation using Vector Space Projection (VSP) methods. The work attacks the Poisson equation as encountered in two-dimensional phase unwrapping problems, and in two-dimensional electrostatic problems. Algorithms are developed by first considering simple one-dimensional cases, and then extending them to two-dimensional problems. In the context of phase unwrapping of two-dimensional phase functions, we explore an approach to the unwrapping using a robust extrapolation-projection algorithm. The unwrapping is done iteratively by modification of the Gerchberg-Papoulis (GP) extrapolation algorithm, and the solution is refined by projecting onto the available global data. An important contribution to the extrapolation algorithm is the formulation of the algorithm with the relaxed bandwidth constraint, and the proof that such modified GP extrapolation algorithm still converges. It is also shown that the unwrapping problem is ill-posed in the VSP setting, and that the modified GP algorithm is the missing link to pushing the iterative algorithm out of the trap solution under certain conditions. Robustness of the algorithm is demonstrated through its performance in a noisy environment. Performance is demonstrated by applying it to phantom phase functions, as well as to the real phase functions. Results are compared to well known algorithms in literature. Unlike many existing unwrapping methods which perform unwrapping locally, this work approaches the unwrapping problem from a globally, and eliminates the need for guiding instruments, like quality maps. VSP algorithm also very effectively battles problems of shadowing and holes, where data is not available or is heavily corrupted. In solving the classical Poisson problems in electrostatics, we demonstrate the effectiveness and ease of implementation of the VSP methodology to solving the equation, as well as imposing of the boundary conditions
Pankratz, C. K.; Baker, D. N.; Jaynes, A. N.; Elkington, S. R.; Baltzer, T.; Sanchez, F.
2017-12-01
Society's growing reliance on complex and highly interconnected technological systems makes us increasingly vulnerable to the effects of space weather events - maybe more than for any other natural hazard. An extreme solar storm today could conceivably impact hundreds of the more than 1400 operating Earth satellites. Such an extreme storm could cause collapse of the electrical grid on continental scales. The effects on navigation, communication, and remote sensing of our home planet could be devastating to our social functioning. Thus, it is imperative that the scientific community address the question of just how severe events might become. At least as importantly, it is crucial that policy makers and public safety officials be informed by the facts on what might happen during extreme conditions. This requires essentially real-time alerts, warnings, and also forecasts of severe space weather events, which in turn demands measurements, models, and associated data products to be available via the most effective data discovery and access methods possible. Similarly, advancement in the fundamental scientific understanding of space weather processes is also vital, requiring that researchers have convenient and effective access to a wide variety of data sets and models from multiple sources. The space weather research community, as with many scientific communities, must access data from dispersed and often uncoordinated data repositories to acquire the data necessary for the analysis and modeling efforts that advance our understanding of solar influences and space physics on the Earth's environment. The Laboratory for Atmospheric and Space Physics (LASP), as a leading institution in both producing data products and advancing the state of scientific understanding of space weather processes, is well positioned to address many of these issues. In this presentation, we will outline the motivating factors for effective space weather data access, summarize the various data
Interpolation of unevenly spaced data using a parabolic leapfrog correction method and cubic splines
Julio L. Guardado; William T. Sommers
1977-01-01
The technique proposed allows interpolation of data recorded at unevenly spaced sites to a regular grid or to other sites. Known data are interpolated to an initial guess field grid of unevenly spaced rows and columns by a simple distance weighting procedure. The initial guess field is then adjusted by using a parabolic leapfrog correction and the known data. The final...
International Nuclear Information System (INIS)
Aviles, B.N.; Sutton, T.M.; Kelly, D.J. III.
1991-09-01
A generalized Runge-Kutta method has been employed in the numerical integration of the stiff space-time diffusion equations. The method is fourth-order accurate, using an embedded third-order solution to arrive at an estimate of the truncation error for automatic timestep control. The efficiency of the Runge-Kutta method is enhanced by a block-factorization technique that exploits the sparse structure of the matrix system resulting from the space and energy discretized form of the time-dependent neutron diffusion equations. Preliminary numerical evaluation using a one-dimensional finite difference code shows the sparse matrix implementation of the generalized Runge-Kutta method to be highly accurate and efficient when compared to an optimized iterative theta method. 12 refs., 5 figs., 4 tabs
Cowings, Patricia S.; Toscano, William B.
1993-01-01
Finding an effective treatment for the motion sickness-like symptoms that occur in space has become a high priority for NASA. The background research is reviewed and the experimental design of a formal life sciences shuttle flight experiment designed to prevent space motion sickness in shuttle crew members is presented. This experiment utilizes a behavioral medicine approach to solving this problem. This method, Autogenic-Feedback Training (AFT), involves training subjects to voluntarily control several of their own physiological responses to environmental stressors. AFT has been used reliably to increase tolerance to motion sickness during ground-based tests in over 200 men and women under a variety of conditions that induce motion sickness, and preliminary evidence from space suggests that AFT may be an effective treatment for space motion sickness as well. Proposed changes to this experiment for future manifests are included.
Gia, Quoc; Mayeli, Azita; Mhaskar, Hrushikesh; Zhou, Ding-Xuan
2017-01-01
The second of a two volume set on novel methods in harmonic analysis, this book draws on a number of original research and survey papers from well-known specialists detailing the latest innovations and recently discovered links between various fields. Along with many deep theoretical results, these volumes contain numerous applications to problems in signal processing, medical imaging, geodesy, statistics, and data science. The chapters within cover an impressive range of ideas from both traditional and modern harmonic analysis, such as: the Fourier transform, Shannon sampling, frames, wavelets, functions on Euclidean spaces, analysis on function spaces of Riemannian and sub-Riemannian manifolds, Fourier analysis on manifolds and Lie groups, analysis on combinatorial graphs, sheaves, co-sheaves, and persistent homologies on topological spaces. Volume II is organized around the theme of recent applications of harmonic analysis to function spaces, differential equations, and data science, covering topics such a...
Methods for assessment of climate variability and climate changes in different time-space scales
International Nuclear Information System (INIS)
Lobanov, V.; Lobanova, H.
2004-01-01
climate changes indexes of such classification have been developed which included: statistical significance or non-significance of climate changes, direction of climate change tendency in conditions of its statistical significance, assessment of its contribution and a form of the tendency if it enough complex over the time. In detected homogeneous regions the spatial generalization is fulfilled which includes different approach in dependence on regularities of spatial features. They are: an averaging, development of spatial distribution functions or spatial simulation. New spatial linear model has been developed and suggested which includes two coefficients connected with a gradient and a level of space field and one parameter which characterizes the internal inhomogeneity of the field. The last step of the suggested methodology is a using of the detected point and field climate changes for determination of design hydrological value. Traditional design characteristics (as one random event in each year) as well as new ones (POT, rare extremes, characteristics of cycles of climate variability), which can be rare or often than one value per year have been chosen. Approach and methods for using of detected climate changes in hydrological computations have been developed. Application of developed methods has been shown on some examples of different hydrometeorological characteristics (floods, low flow, annual runoff, monthly and annual temperature and precipitation) in some regions with different climatic conditions.(Author)
The effects of cooperative learning methods on minority ninth graders in earth and space science
Eshietedoho, Cobb G.
This research was conducted using a quasi-experimental study design. The study took place at a local high school in the Miami-Dade County Public School System, the 4th largest school system in the nation. Students in the researcher's high school class were entering high school for the first time and were promoted into 9th grade at the end of the 2008--2009 school year. The observed problem that necessitated the study had been noticed during the writer's tenure at the school. The minority students, Blacks and Hispanics in particular, were underperforming in the researcher's earth science class when compared to their White and Asian American counterparts. The researcher conducted the study for the purpose of determining whether cooperative learning through active engagement techniques could enhance these students' achievement in earth and space science. The researcher used a cooperative learning technique in combination with technology integration, research activities, laboratory experimentation, and other aspects of group projects to engage students in a collaborative effort with the hope of enhancing their performance. The method involved grouping students using Kagan's numerical system. Students were placed in groups of 4, which included 1 high achiever, 2 average achievers, and 1 low achiever. The placement process utilized the incoming students' 8th-grade Florida Comprehensive Assessment Test science results. Placement was carried out after the researcher had the opportunity to observe the students so that groups did not contain friends and adversaries or all-male or all-female members. The premise for using this technique was to engage the students actively, help them become self-reliant, develop skills in teamwork, and work cooperatively to contribute equally to each other's success. A paired sample t test was conducted to evaluate the hypothesis that achievement scores from the posttest would be statistically more significant than the pretest. The test was
Yin, Xianghui; Wang, Rui; Wang, Shaoxin; Wang, Yukun; Jin, Chengbin; Cao, Zhaoliang; Xuan, Li
2018-02-01
Atmospheric turbulence seriously affects the quality of free-space laser communication. The Strehl ratio (SR) is used to evaluate the effect of atmospheric turbulence on the receiving energy of free-space laser communication systems. However, the SR method does not consider the area of the laser-receiving end face. In this study, the power-in-the-bucket (PIB) method is demonstrated to accurately evaluate the effect of turbulence on the receiving energy. A theoretical equation is first obtained to calculate PIB. Simulated and experimental validations are then performed to verify the effectiveness of the theoretical equation. This work may provide effective guidance for the design and evaluation of free-space laser communication systems.
Active Vibration Control Method for Space Truss Using Piezoelectric Actuators and Finite Elements
National Research Council Canada - National Science Library
Pantling, Carey
1999-01-01
.... With the use of a dSPACE data acquisition and processing system, quartz force transducer and piezoelectric actuator, active controls using an integral plus double integral control law were used...
Innovative Methods for the Benefit of Public Health Using Space Technologies for Disaster Response.
Dinas, Petros C; Mueller, Christian; Clark, Nathan; Elgin, Tim; Nasseri, S Ali; Yaffe, Etai; Madry, Scott; Clark, Jonathan B; Asrar, Farhan
2015-06-01
Space applications have evolved to play a significant role in disaster relief by providing services including remote sensing imagery for mitigation and disaster damage assessments; satellite communication to provide access to medical services; positioning, navigation, and timing services; and data sharing. Common issues identified in past disaster response and relief efforts include lack of communication, delayed ordering of actions (eg, evacuations), and low levels of preparedness by authorities during and after disasters. We briefly summarize the Space for Health (S4H) Team Project, which was prepared during the Space Studies Program 2014 within the International Space University. The S4H Project aimed to improve the way space assets and experiences are used in support of public health during disaster relief efforts. We recommend an integrated solution based on nano-satellites or a balloon communication system, mobile self-contained relief units, portable medical scanning devices, and micro-unmanned vehicles that could revolutionize disaster relief and disrupt different markets. The recommended new system of coordination and communication using space assets to support public health during disaster relief efforts is feasible. Nevertheless, further actions should be taken by governments and organizations in collaboration with the private sector to design, test, and implement this system.
Ghosh, Soumen; Cramer, Christopher J; Truhlar, Donald G; Gagliardi, Laura
2017-04-01
Predicting ground- and excited-state properties of open-shell organic molecules by electronic structure theory can be challenging because an accurate treatment has to correctly describe both static and dynamic electron correlation. Strongly correlated systems, i.e. , systems with near-degeneracy correlation effects, are particularly troublesome. Multiconfigurational wave function methods based on an active space are adequate in principle, but it is impractical to capture most of the dynamic correlation in these methods for systems characterized by many active electrons. We recently developed a new method called multiconfiguration pair-density functional theory (MC-PDFT), that combines the advantages of wave function theory and density functional theory to provide a more practical treatment of strongly correlated systems. Here we present calculations of the singlet-triplet gaps in oligoacenes ranging from naphthalene to dodecacene. Calculations were performed for unprecedently large orbitally optimized active spaces of 50 electrons in 50 orbitals, and we test a range of active spaces and active space partitions, including four kinds of frontier orbital partitions. We show that MC-PDFT can predict the singlet-triplet splittings for oligoacenes consistent with the best available and much more expensive methods, and indeed MC-PDFT may constitute the benchmark against which those other models should be compared, given the absence of experimental data.
Hong, Baojian; Lu, Dianchen
2014-01-01
Based on He's variational iteration method idea, we modified the fractional variational iteration method and applied it to construct some approximate solutions of the generalized time-space fractional Schrödinger equation (GFNLS). The fractional derivatives are described in the sense of Caputo. With the help of symbolic computation, some approximate solutions and their iterative structure of the GFNLS are investigated. Furthermore, the approximate iterative series and numerical results show that the modified fractional variational iteration method is powerful, reliable, and effective when compared with some classic traditional methods such as homotopy analysis method, homotopy perturbation method, adomian decomposition method, and variational iteration method in searching for approximate solutions of the Schrödinger equations.
Directory of Open Access Journals (Sweden)
Baojian Hong
2014-01-01
Full Text Available Based on He’s variational iteration method idea, we modified the fractional variational iteration method and applied it to construct some approximate solutions of the generalized time-space fractional Schrödinger equation (GFNLS. The fractional derivatives are described in the sense of Caputo. With the help of symbolic computation, some approximate solutions and their iterative structure of the GFNLS are investigated. Furthermore, the approximate iterative series and numerical results show that the modified fractional variational iteration method is powerful, reliable, and effective when compared with some classic traditional methods such as homotopy analysis method, homotopy perturbation method, adomian decomposition method, and variational iteration method in searching for approximate solutions of the Schrödinger equations.
Application of the space-time conservation element and solution element method to shock-tube problem
Wang, Xiao-Yen; Chow, Chuen-Yen; Chang, Sin-Chung
1994-01-01
An Euler solver based on the method of space-time conservation element and solution element is in this paper to simulate shock-tube flows involving shock waves, contact discontinuities, expansion waves and their intersections. Seven test problems are considered to examine the capability of this method. The numerical results, when compared with exact solutions and/or numerical solutions by other methods, indicate that the present method can accurately resolve strong shock and contact discontinuities without using any ad hoc techniques which are used only at the neighborhood of a discontinuity.
Gao, Xin; Wang, Yifan; Sun, Hanxu; Jia, Qingxuan; Chen, Gang; Du, Mingtao; Yang, Yukun
2016-01-01
In order to maintain and enhance the operational reliability of a robotic manipulator deployed in space, an operational reliability system control method is presented in this paper. First, a method to divide factors affecting the operational reliability is proposed, which divides the operational reliability factors into task-related factors and cost-related factors. Then the models describing the relationships between the two kinds of factors and control variables are established. Based on th...
Pandey, Rishi Kumar; Mishra, Hradyesh Kumar
2017-03-01
The time and space fractional wave and heat type equations with variable coefficients are considered, and the variable order derivative in He`s fractional derivative sense are taken. The utility of the homotopy analysis fractional sumudu transform method is shown in the form of a series solution for these generalized fractional order equations. Some discussion with examples are presented to explain the accuracy and ease of the method.
Knudsen, Steven; Golubovic, Leonardo
2015-04-01
With the advent of ultra-strong materials, the Space Elevator has changed from science fiction to real science. We discuss computational and theoretical methods we developed to explore classical and statistical mechanics of rotating Space Elevators (RSE). An RSE is a loopy string reaching deep into outer space. The floppy RSE loop executes a motion which is nearly a superposition of two rotations: geosynchronous rotation around the Earth, and yet another faster rotational motion of the string which goes on around a line perpendicular to the Earth at its equator. Strikingly, objects sliding along the RSE loop spontaneously oscillate between two turning points, one of which is close to the Earth (starting point) whereas the other one is deeply in the outer space. The RSE concept thus solves a major problem in space elevator science which is how to supply energy to the climbers moving along space elevator strings. The exploration of the dynamics of a floppy string interacting with objects sliding along it has required development of novel finite element algorithms described in this presentation. We thank Prof. Duncan Lorimer of WVU for kindly providing us access to his computational facility.
Dittermore, Gary; Bertels, Christie
2011-01-01
Operations of human spaceflight systems is extremely complex; therefore, the training and certification of operations personnel is a critical piece of ensuring mission success. Mission Control Center (MCC-H), at the Lyndon B. Johnson Space Center in Houston, Texas, manages mission operations for the Space Shuttle Program, including the training and certification of the astronauts and flight control teams. An overview of a flight control team s makeup and responsibilities during a flight, and details on how those teams are trained and certified, reveals that while the training methodology for developing flight controllers has evolved significantly over the last thirty years the core goals and competencies have remained the same. In addition, the facilities and tools used in the control center have evolved. Changes in methodology and tools have been driven by many factors, including lessons learned, technology, shuttle accidents, shifts in risk posture, and generational differences. Flight controllers share their experiences in training and operating the space shuttle. The primary training method throughout the program has been mission simulations of the orbit, ascent, and entry phases, to truly train like you fly. A review of lessons learned from flight controller training suggests how they could be applied to future human spaceflight endeavors, including missions to the moon or to Mars. The lessons learned from operating the space shuttle for over thirty years will help the space industry build the next human transport space vehicle.
Directory of Open Access Journals (Sweden)
Ah-Long Son
2016-11-01
Full Text Available This study proposed two methods, boundary-type and pond-type, to link overland and underground space in urban flood modeling. The boundary-type treats the exit of underground space as an interface for inflow of floodwater by imposing open boundary condition and pond-type considers underground space as an underground pond by configuring pond terrain. The effect of underground space in urban flood inundation was examined by coupling one-dimensional (1D stormwater management model (SWMM and two-dimensional (2D overland flood model. The models were applied to the Hyoja drainage basin, Seoul, Korea where urban flood occurred due to heavy rainfall in 21 September 2010. The conduit roughness coefficient of SWMM was calibrated to minimize the difference between observed and predicted water depth of pipe. In addition, the surface roughness coefficient of 2D model was calibrated by comparing observed and predicted flood extent. Then, urban flood analysis was performed on three different scenarios involving a case not considering underground (Case 1 and cases considering underground, boundary-type (Case 2 and pond-type (Case 3. The simulation results have shown that the boundary-type is simple but robust method with high computational efficiency to link overland and underground space in urban flood modeling.
Riedell, James A. (Inventor); Easler, Timothy E. (Inventor)
2009-01-01
A precursor of a ceramic adhesive suitable for use in a vacuum, thermal, and microgravity environment. The precursor of the ceramic adhesive includes a silicon-based, preceramic polymer and at least one ceramic powder selected from the group consisting of aluminum oxide, aluminum nitride, boron carbide, boron oxide, boron nitride, hafnium boride, hafnium carbide, hafnium oxide, lithium aluminate, molybdenum silicide, niobium carbide, niobium nitride, silicon boride, silicon carbide, silicon oxide, silicon nitride, tin oxide, tantalum boride, tantalum carbide, tantalum oxide, tantalum nitride, titanium boride, titanium carbide, titanium oxide, titanium nitride, yttrium oxide, zirconium diboride, zirconium carbide, zirconium oxide, and zirconium silicate. Methods of forming the ceramic adhesive and of repairing a substrate in a vacuum and microgravity environment are also disclosed, as is a substrate repaired with the ceramic adhesive.
Nashed, G. G. L.
2015-10-01
A tetrad field, which gives Schwarzschild-NUT-AdS metric, is provided. We calculate the total conserved charges of this tetrad. This is done by using "regularization through relocalization" for the first time. This method gives the correct value of the total charge of Schwarzschild-NUT-AdS space-time, which depends on the gravitational mass of the system. We show that the NUT parameter has no physical meaning on the conserved quantities of the Schwarzschild-NUT-AdS space-time.
Niemi, Antti
2011-05-14
We revisit the finite element analysis of convection dominated flow problems within the recently developed Discontinuous Petrov-Galerkin (DPG) variational framework. We demonstrate how test function spaces that guarantee numerical stability can be computed automatically with respect to the so called optimal test space norm by using an element subgrid discretization. This should make the DPG method not only stable but also robust, that is, uniformly stable with respect to the Ṕeclet number in the current application. The e_ectiveness of the algorithm is demonstrated on two problems for the linear advection-di_usion equation.
Effective Numerical Methods for Solving Elliptical Problems in Strengthened Sobolev Spaces
D'yakonov, Eugene G.
1996-01-01
Fourth-order elliptic boundary value problems in the plane can be reduced to operator equations in Hilbert spaces G that are certain subspaces of the Sobolev space W(sub 2)(exp 2)(Omega) is identical with G(sup (2)). Appearance of asymptotically optimal algorithms for Stokes type problems made it natural to focus on an approach that considers rot w is identical with (D(sub 2)w - D(sub 1)w) is identical with vector of u as a new unknown vector-function, which automatically satisfies the condition div vector of u = 0. In this work, we show that this approach can also be developed for an important class of problems from the theory of plates and shells with stiffeners. The main mathematical problem was to show that the well-known inf-sup condition (normal solvability of the divergence operator) holds for special Hilbert spaces. This result is also essential for certain hydrodynamics problems.
A space-time adaptive method for simulating complex cardiac dynamics.
Cherry, E M; Greenside, H S; Henriquez, C S
2000-02-07
For plane-wave and many-spiral states of the experimentally based Luo-Rudy 1 model of heart tissue in large (8 cm square) domains, we show that a space-time-adaptive time-integration algorithm can achieve a factor of 5 reduction in computational effort and memory-but without a reduction in accuracy-when compared to an algorithm using a uniform space-time mesh at the finest resolution. Our results indicate that such an algorithm can be extended straightforwardly to simulate quantitatively three-dimensional electrical dynamics over the whole human heart.
Dósa, M.; Opitz, A.; Szegő, K.
2017-09-01
Concerning the increasing number of heliospheric space missions it is a key issue to foresee space weather conditions in the spacecraft's and the target object's neighborhood. Solar wind parameters are propagated to outer orbits by several ballistic and magnetohydrodynamic (MHD) methods. The ballistic model presented here is enhanced by adjusting for the target movement during the propagation time through a two-step method. First, the magnetic field line connecting the Sun and the target has to be found. Once the proper magnetic field line is found, solar wind bulk velocity, density and magnetic field polarity is propagated assuming no change during travel time. The method was tested successfully during the Rosetta mission. While the spacecraft was investigating the close environment of the comet Churyumov-Gerasimenko it was necessary to know the properties of the ambient solar wind in order to evaluate data and account for the dynamic changes.
Jiao, C. F.; Engel, J.; Holt, J. D.
2017-11-01
We use the generator-coordinate method (GCM) with realistic shell-model interactions to closely approximate full shell-model calculations of the matrix elements for the neutrinoless double-β decay of 48Ca, 76Ge, and 82Se. We work in one major shell for the first isotope, in the f5 /2p g9 /2 space for the second and third, and finally in two major shells for all three. Our coordinates include not only the usual axial deformation parameter β , but also the triaxiality angle γ and neutron-proton pairing amplitudes. In the smaller model spaces our matrix elements agree well with those of full shell-model diagonalization, suggesting that our Hamiltonian-based GCM captures most of the important valence-space correlations. In two major shells, where exact diagonalization is not currently possible, our matrix elements are only slightly different from those in a single shell.
Space-planning and structural solutions of low-rise buildings: Optimal selection methods
Gusakova, Natalya; Minaev, Nikolay; Filushina, Kristina; Dobrynina, Olga; Gusakov, Alexander
2017-11-01
The present study is devoted to elaboration of methodology used to select appropriately the space-planning and structural solutions in low-rise buildings. Objective of the study is working out the system of criteria influencing the selection of space-planning and structural solutions which are most suitable for low-rise buildings and structures. Application of the defined criteria in practice aim to enhance the efficiency of capital investments, energy and resource saving, create comfortable conditions for the population considering climatic zoning of the construction site. Developments of the project can be applied while implementing investment-construction projects of low-rise housing at different kinds of territories based on the local building materials. The system of criteria influencing the optimal selection of space-planning and structural solutions of low-rise buildings has been developed. Methodological basis has been also elaborated to assess optimal selection of space-planning and structural solutions of low-rise buildings satisfying the requirements of energy-efficiency, comfort and safety, and economical efficiency. Elaborated methodology enables to intensify the processes of low-rise construction development for different types of territories taking into account climatic zoning of the construction site. Stimulation of low-rise construction processes should be based on the system of approaches which are scientifically justified; thus it allows enhancing energy efficiency, comfort, safety and economical effectiveness of low-rise buildings.
Aerts, Sven
2011-12-01
We introduce vector space based approaches to natural language processing and some of their similarities with quantum theory when applied to information retrieval. We explain how dimensional reduction is called for from both a practical and theoretical point of view and how this can be achieved through choice of product or through projectors onto subspaces.
The set up of an evaluation method to judge the effectiveness of the space time cube
DEFF Research Database (Denmark)
Kveladze, Irma; Kraak, Menno-Jan
2012-01-01
Over the last years an increased interest in the use of the space-time cube to visualize movement data can be witnessed. However, little is known if the cube is truly efficient, and effective to satisfactory display complex movement datasets. Limited usability research has been done. This paper d...
Qualitative methods to explore thermo-spatial perception in outdoor urban spaces
Lenzholzer, S.; Klemm, W.; Vasilikou, Carolina
2018-01-01
To be able to design thermally comfortable urban spaces, designers require design guidelines that respond to people's thermal and spatial perception. This thermo-spatial perception is influenced by a range of dimensions: the nature and scale of spatial contexts, the kinetic state of the people and
Directory of Open Access Journals (Sweden)
A. V. Markeeva
2017-01-01
Full Text Available T his article deals with transformation of consumer practices, which become (and maybe have already turned into the dominated form of social behavior and cannot be described within the model of purposeful-rational action. Utilizing the analytical distinction between “doing shopping” as routine practice, related to satisfaction of basic needs, and “going shopping” as pleasure and leasuretime social activity, this article demonstrates series of changes, resulting in generation of new consumer culture. These changes are compared with a range of transfigurations of the consumers’ spaces (trade spaces, which are at once places (scenes, where consumer practices deploy, and the structural condition of their possibility. According to the logic of the modern man, his focus on fast and diverse consumption and his desire of consuming everything in one place, “in one bottle” on the run, the shopping spaces are becoming the center of new industries-cultural, educational, recreational. The modern retail spaces become not only a place of shopping, but also closely incorporate into the social life of the community and turn into the centers of social life. Effectively combining and managing the various scenarios of consumption, the modern retail helps to feel and join the happiness of live communication in the overbounded with the online social contacts, but atomized world, to get rid of the feeling of emotional emptiness. Special design of retail space and the integration of various social technologies, which are created for manipulating the emotional sphere of the customers (non-standard architectural solutions, catchy window dressing, interior design, background music, aromamarketing, psychologically adjusted range of color, taste and tactile solutions create a special entertainment and attraction of space, control the consumer and are ready not only to stimulate the purchase, but to form an unforgettable impressions. P roducers and retailers
Ryan, Robert S.; Townsend, John S.
1993-01-01
The prospective improvement of probabilistic methods for space program analysis/design entails the further development of theories, codes, and tools which match specific areas of application, the drawing of lessons from previous uses of probability and statistics data bases, the enlargement of data bases (especially in the field of structural failures), and the education of engineers and managers on the advantages of these methods. An evaluation is presently made of the current limitations of probabilistic engineering methods. Recommendations are made for specific applications.
Directory of Open Access Journals (Sweden)
Kezerashvili Roman Ya.
2014-01-01
Full Text Available The kaonic clusters K̄NN and K̄NNN are studied within the method of hyperspherical functions in the momentum representation. Binding energies and widths of three- and four-body nuclear quasibound states are calculated by employing realistic NN potentials and the energy dependent chiral K̄N interaction, as well as a phenomenological K̄N potential. The comparison of the results of calculations obtained in the framework of the variational method, Faddeev, Faddeev-Yakubovsky equations, and method of hyperspherical functions in configuration space are discussed.
Johnson, C. W.
2010-09-01
Configuration management ensures that the requirements and constraints, identified in previous stages of development, are preserved throughout the design, implementation and operation of complex systems. Space-related, software systems pose particular problems because, for instance, it can be hard to determine what code is actually running on a platform as successive updates are performed over many months of remote operation. It is, therefore, important we learn as much as possible from previous mishaps that have involved configuration management; given that software continues to play a critical role in the safety of many space missions. The following pages extend the US Air Force’s 8-Step Method to identify lessons learned from space related incidents. This approach builds on Boyd’s OODA(Observe, Orient, Decide and Act) Loop and provides a common framework for the analysis of these complex incidents. It is important to stress that the application of an existing general approach to problem solving, rather than the development of a specific approach for configuration management, is intended to reduce training costs and to increase the value added from existing investments in the use of the 8-Step Method. Many specialised software engineering techniques are not used because they cannot easily be applied within the financial limits and deadlines that constrain most space programmes. The closing sections of this paper identify areas for further work; in particular, we stress the importance of links with recent European Space Agency problem solving techniques that support the early-stage development of long duration space missions.
Himansu, Ananda; Chang, Sin-Chung; Yu, Sheng-Tao; Wang, Xiao-Yen; Loh, Ching-Yuen; Jorgenson, Philip C. E.
1999-01-01
In this overview paper, we review the basic principles of the method of space-time conservation element and solution element for solving the conservation laws in one and two spatial dimensions. The present method is developed on the basis of local and global flux conservation in a space-time domain, in which space and time are treated in a unified manner. In contrast to the modern upwind schemes, the approach here does not use the Riemann solver and the reconstruction procedure as the building blocks. The drawbacks of the upwind approach, such as the difficulty of rationally extending the 1D scalar approach to systems of equations and particularly to multiple dimensions is here contrasted with the uniformity and ease of generalization of the Conservation Element and Solution Element (CE/SE) 1D scalar schemes to systems of equations and to multiple spatial dimensions. The assured compatibility with the simplest type of unstructured meshes, and the uniquely simple nonreflecting boundary conditions of the present method are also discussed. The present approach has yielded high-resolution shocks, rarefaction waves, acoustic waves, vortices, ZND detonation waves, and shock/acoustic waves/vortices interactions. Moreover, since no directional splitting is employed, numerical resolution of two-dimensional calculations is comparable to that of the one-dimensional calculations. Some sample applications displaying the strengths and broad applicability of the CE/SE method are reviewed.
Directory of Open Access Journals (Sweden)
V. V. Zelentsov
2017-01-01
Full Text Available Significant amount of space debris available in the near-Earth space is a reason to protect space vehicles from the fragments of space debris. Existing empirical calculation methods do not allow us to estimate quality of developed protection. Experimental verification of protection requires complex and expensive installations that do not allow having a desirable impact velocity. The article proposes to use the ANSYS AUTODYN software environment – a software complex of the nonlinear dynamic analysis to evaluate quality of developed protection. The ANSYS AUTODYN environment is based on the integration methods of a system of equations of continuum mechanics. The SPH (smoothed particle method method is used as a solver. The SPH method is based on the area of sampling by a finite set of the Lagrangian particles that can be represented as the elementary volumes of the medium. In modeling the targets were under attack of 2 and 3 mm spheres and cylinders with 2 mm in bottom diameter and with generator of 2 and 3 mm. The apheres and cylinders are solid and hollow, with a wall thickness of 0.5 mm. The impact velocity of the particles with a target was assumed to be 7.5 km / s. The number of integration cycles in all cases of calculation was assumed to be 1000. The rate of flying debris fragments of the target material as a function of the h / d ratio (h - the thickness of the target, / d - the diameter of a sphere or a cylinder end is obtained. In simulation the sample picture obtained coincides both with results of experimental study carried out at the Tomsk State Technical University and with results described in the literature.
Kou, Zhuangfei; Shen, Jun; Xu, Enhua; Li, Shuhua
2012-05-21
Based on the coupled-cluster singles, doubles, and a hybrid treatment of triples (CCSD(T)-h) method developed by us [J. Shen, E. Xu, Z. Kou, and S. Li, J. Chem. Phys. 132, 114115 (2010); and ibid. 133, 234106 (2010); and ibid. 134, 044134 (2011)], we developed and implemented a new hybrid coupled cluster (CC) method, named CCSD(T)q-h, by combining CC singles and doubles, and active triples and quadruples (CCSDtq) with CCSD(T) to deal with the electronic structures of molecules with significant multireference character. These two hybrid CC methods can be solved with non-canonical and canonical MOs. With canonical MOs, the CCSD(T)-like equations in these two methods can be solved directly without iteration so that the storage of all triple excitation amplitudes can be avoided. A practical procedure to divide canonical MOs into active and inactive subsets is proposed. Numerical calculations demonstrated that CCSD(T)-h with canonical MOs can well reproduce the corresponding results obtained with non-canonical MOs. For three atom exchange reactions, we found that CCSD(T)-h can offer a significant improvement over the popular CCSD(T) method in describing the reaction barriers. For the bond-breaking processes in F(2) and H(2)O, our calculations demonstrated that CCSD(T)q-h is a good approximation to CCSDTQ over the entire bond dissociation processes.
Trivailo, O.; Sippel, M.; Şekercioğlu, Y. A.
2012-08-01
The primary purpose of this paper is to review currently existing cost estimation methods, models, tools and resources applicable to the space sector. While key space sector methods are outlined, a specific focus is placed on hardware cost estimation on a system level, particularly for early mission phases during which specifications and requirements are not yet crystallised, and information is limited. For the space industry, cost engineering within the systems engineering framework is an integral discipline. The cost of any space program now constitutes a stringent design criterion, which must be considered and carefully controlled during the entire program life cycle. A first step to any program budget is a representative cost estimate which usually hinges on a particular estimation approach, or methodology. Therefore appropriate selection of specific cost models, methods and tools is paramount, a difficult task given the highly variable nature, scope as well as scientific and technical requirements applicable to each program. Numerous methods, models and tools exist. However new ways are needed to address very early, pre-Phase 0 cost estimation during the initial program research and establishment phase when system specifications are limited, but the available research budget needs to be established and defined. Due to their specificity, for vehicles such as reusable launchers with a manned capability, a lack of historical data implies that using either the classic heuristic approach such as parametric cost estimation based on underlying CERs, or the analogy approach, is therefore, by definition, limited. This review identifies prominent cost estimation models applied to the space sector, and their underlying cost driving parameters and factors. Strengths, weaknesses, and suitability to specific mission types and classes are also highlighted. Current approaches which strategically amalgamate various cost estimation strategies both for formulation and validation
Phase-space methods for the spin dynamics in condensed matter systems
Hurst, Jérôme; Hervieux, Paul-Antoine; Manfredi, Giovanni
2017-03-01
Using the phase-space formulation of quantum mechanics, we derive a four-component Wigner equation for a system composed of spin- fermions (typically, electrons) including the Zeeman effect and the spin-orbit coupling. This Wigner equation is coupled to the appropriate Maxwell equations to form a self-consistent mean-field model. A set of semiclassical Vlasov equations with spin effects is obtained by expanding the full quantum model to first order in the Planck constant. The corresponding hydrodynamic equations are derived by taking velocity moments of the phase-space distribution function. A simple closure relation is proposed to obtain a closed set of hydrodynamic equations. This article is part of the themed issue 'Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces'.
A new method for power generation and distribution in outer space
Energy Technology Data Exchange (ETDEWEB)
Bamberger, J.A.
1989-09-01
The power system is a major component of a space system's size, mass, technical complexity, and hence, cost. To date, space systems include the energy source as an integral part of the mission satellite. Potentially significant benefit could be realized by separating the energy source from the end-use system and transmitting the power via an energy beam (power beaming) (Coomes et al., 1989). This concept parallels the terrestrial central generating station and transmission grid. In this summary, the system components required for power beaming implementation are outlined and applied to a satellite for power beaming implementation are outlined and applied to a satellite constellation to demonstrate the feasibility of implementing power beaming in the next 20 years. 5 refs., 1 fig., 3 tabs.
Babiak-Vazquez, Adriana; Ruffaner, Lanie; Wear, Mary; Crucian Brian; Sams, Clarence; Lee, Lesley R.; Van Baalen, Mary
2016-01-01
Space medicine presents unique challenges and opportunities for epidemiologists, such as the use of telemedicine during spaceflight. Medical capabilities aboard the International Space Station (ISS) are limited due to severe restrictions on power, volume, and mass. Consequently, inflight health information is based heavily on crewmember (CM) self-report of signs and symptoms, rather than formal diagnoses. While CM's are in flight, the primary source of crew health information is verbal communication between physicians and crewmembers. In 2010 NASA implemented the Lifetime Surveillance of Astronaut Health, an occupational surveillance program for the U.S. Astronaut corps. This has shifted the epidemiological paradigm from tracking diagnoses based on traditional terrestrial clinical practice to one that incorporates symptomatology and may gain a more population-based understanding of early detection of disease process.
Flight Dynamics Operations: Methods and Lessons Learned from Space Shuttle Orbit Operations
Cutri-Kohart, Rebecca M.
2011-01-01
The Flight Dynamics Officer is responsible for trajectory maintenance of the Space Shuttle. This paper will cover high level operational considerations, methodology, procedures, and lessons learned involved in performing the functions of orbit and rendezvous Flight Dynamics Officer and leading the team of flight dynamics specialists during different phases of flight. The primary functions that will be address are: onboard state vector maintenance, ground ephemeris maintenance, calculation of ground and spacecraft acquisitions, collision avoidance, burn targeting for the primary mission, rendezvous, deorbit and contingencies, separation sequences, emergency deorbit preparation, mass properties coordination, payload deployment planning, coordination with the International Space Station, and coordination with worldwide trajectory customers. Each of these tasks require the Flight Dynamics Officer to have cognizance of the current trajectory state as well as the impact of future events on the trajectory plan in order to properly analyze and react to real-time changes. Additionally, considerations are made to prepare flexible alternative trajectory plans in the case timeline changes or a systems failure impact the primary plan. The evolution of the methodology, procedures, and techniques used by the Flight Dynamics Officer to perform these tasks will be discussed. Particular attention will be given to how specific Space Shuttle mission and training simulation experiences, particularly off-nominal or unexpected events such as shortened mission durations, tank failures, contingency deorbit, navigation errors, conjunctions, and unexpected payload deployments, have influenced the operational procedures and training for performing Space Shuttle flight dynamics operations over the history of the program. These lessons learned can then be extended to future vehicle trajectory operations.
Chan, William M.
1995-01-01
Algorithms and computer code developments were performed for the overset grid approach to solving computational fluid dynamics problems. The techniques developed are applicable to compressible Navier-Stokes flow for any general complex configurations. The computer codes developed were tested on different complex configurations with the Space Shuttle launch vehicle configuration as the primary test bed. General, efficient and user-friendly codes were produced for grid generation, flow solution and force and moment computation.
Wan, Yong
2012-02-01
2D image space methods are processing methods applied after the volumetric data are projected and rendered into the 2D image space, such as 2D filtering, tone mapping and compositing. In the application domain of volume visualization, most 2D image space methods can be carried out more efficiently than their 3D counterparts. Most importantly, 2D image space methods can be used to enhance volume visualization quality when applied together with volume rendering methods. In this paper, we present and discuss the applications of a series of 2D image space methods as enhancements to confocal microscopy visualizations, including 2D tone mapping, 2D compositing, and 2D color mapping. These methods are easily integrated with our existing confocal visualization tool, FluoRender, and the outcome is a full-featured visualization system that meets neurobiologists\\' demands for qualitative analysis of confocal microscopy data. © 2012 IEEE.
Using observational methods to evaluate public open spaces and physical activity in Brazil.
Hino A A, F; Reis, Rodrigo S; Ribeiro, Isabela C; Parra, Diana C; Brownson, Ross C; Fermino, Rogerio C
2010-07-01
Open public spaces have been identified as important facilities to promote physical activity (PA) at the community level. The main goals of this study are to describe open public spaces user's characteristics and to explore to what extent these characteristics are associated with PA behavior. A system of direct observation was used to evaluate the PA levels on parks and squares (smaller parks) and users's characteristics (gender and age). The 4 parks and 4 squares observed were selected from neighborhoods with different socioeconomic status and environmental characteristics. The settings were observed 3 times a day, 6 days per week, during 2 weeks. More men than women were observed in parks (63.1%) and squares (70.0%) as well as more adults and adolescents than older adults and children. Users were more physically active in parks (men = 34.1%, women = 36.1%) than in squares (men = 25.5%, women 22.8%). The characteristics of public open spaces may affect PA in the observed places. Initiatives to improve PA levels in community settings should consider users' characteristics and preferences to be more effective and reach a larger number of people.
A Quality Function Deployment Method Applied to Highly Reusable Space Transportation
Zapata, Edgar
2016-01-01
This paper will describe a Quality Function Deployment (QFD) currently in work the goal of which is to add definition and insight to the development of long term Highly Reusable Space Transportation (HRST). The objective here is twofold. First, to describe the process, the actual QFD experience as applies to the HRST study. Second, to describe the preliminary results of this process, in particular the assessment of possible directions for future pursuit such as promising candidate technologies or approaches that may finally open the space frontier. The iterative and synergistic nature of QFD provides opportunities in the process for the discovery of what is key in so far as it is useful, what is not, and what is merely true. Key observations on the QFD process will be presented. The importance of a customer definition as well as the similarity of the process of developing a technology portfolio to product development will be shown. Also, the relation of identified cost and operating drivers to future space vehicle designs that are robust to an uncertain future will be discussed. The results in particular of this HRST evaluation will be preliminary given the somewhat long term (or perhaps not?) nature of the task being considered.
The Study of Importance of the Balance Space Food -Storage Method -
Katayama, Naomi; Yamashita, Masamichi; Hashimoto, Hirofumi; Space Agriculture Task Force, J.
Providing foods to space crew is the important requirements to support long term manned space exploration. Foods fill not only physiological requirements to sustain life, but psychological needs for refreshment and joy during the long and hard mission to extraterrestrial planets. We designed joyful and healthy recipe with materials, which can be produced by the bio-regenerative agricultural system operated at limited resources available in Mars base, Moon base and spaceship. We need to think about how to use the storage food when we have the time of emergency. The pupa of the silkworm becomes the important nourishment source as protein and lipid. The silk thread uses it as clothing and cosmetics and medical supplies. However, we can use the silk thread as food as protein. The silk thread is mad of sericin and fibroin. The sericin is used for cosmetics mainly, but can make sheet food by mixing it with rice flour. We can make Japanese rolled sushi with this product. In addition, we can make spring roll and gyoza and shao-mai. As for the fibroin which is the subject of the silk thread, is to extract it high pressure heat; of the protein can powder it, and can use it as food. Even if there is the silk thread in this way after having made it clothes once, we can do it to food again. We can reuse the cotton thread as carbohydrates equally, too. We can use the wood as carbohydrates, also. Based upon the foregoing, we use the pupa of the silkworm as protein and lipid, and the silk thread as protein, and the cotton thread and wood as carbohydrates. It is recommended as healthy meal balance; Protein: Lipid: Carbohydrate ratio equal 15-20We succeeded to develop joyful and nutritious space recipe at the end. Since energy consumption for physical exercise activities under micro-or sub-gravity is less than the terrestrial case, choice of our space foods is essencial to suppress blood sugar level, and prevent the metabolic syndrome. Because of less need of agricultural resources
Lyashenko, I A; Popov, V L
2015-02-16
An impact of an elastic sphere with an elastic half space under no-slip conditions (infinitely large coefficient of friction) is studied numerically using the method of dimensionality reduction. It is shown that the rebound velocity and angular velocity, written as proper dimensionless variables, are determined by a function of only the ratio of tangential and normal stiffness ("Mindlin-ratio"). The obtained numerical results can be approximated by a simple analytical expression.
Space systems conceptual design : Analysis methods for engineering-team support
Ridolfi, G.
2013-01-01
The research can be placed in the framework of designing methods for complex systems focused on the conceptual design phase of the systems’ life-cycle. More specifically, the methods presented in the dissertation belong to the category of Operational Research methods. They aim at the creation of
PDE-Foam - a probability-density estimation method using self-adapting phase-space binning
Dannheim, Dominik; Voigt, Alexander; Grahn, Karl-Johan; Speckmayer, Peter
2009-01-01
Probability-Density Estimation (PDE) is a multivariate discrimination technique based on sampling signal and background densities defined by event samples from data or Monte-Carlo (MC) simulations in a multi-dimensional phase space. To efficiently use large event samples to estimate the probability density, a binary search tree (range searching) is used in the PDE-RS implementation. It is a generalisation of standard likelihood methods and a powerful classification tool for problems with highly non-linearly correlated observables. In this paper, we present an innovative improvement of the PDE method that uses a self-adapting binning method to divide the multi-dimensional phase space in a finite number of hyper-rectangles (cells). The binning algorithm adjusts the size and position of a predefined number of cells inside the multidimensional phase space, minimizing the variance of the signal and background densities inside the cells. The binned density information is stored in binary trees, allowing for a very ...
A new method of testing space-based high-energy electron detectors with radioactive electron sources
International Nuclear Information System (INIS)
Zhang, S.Y.; Shen, G.H.; Sun, Y.; Zhou, D.Z.; Zhang, X.X.; Li, J.W.; Huang, C.; Zhang, X.G.; Dong, Y.J.; Zhang, W.J.; Zhang, B.Q.; Shi, C.Y.
2016-01-01
Space-based electron detectors are commonly tested using radioactive β-sources which emit a continuous spectrum without spectral lines. Therefore, the tests are often to be considered only qualitative. This paper introduces a method, which results in more than a qualitative test even when using a β-source. The basic idea is to use the simulated response function of the instrument to invert the measured spectrum and compare this inverted spectrum with a reference spectrum obtained from the same source. Here we have used Geant4 to simulate the instrument response function (IRF) and a 3.5 mm thick Li-drifted Si detector to obtain the reference 90 Sr/ 90 Yi source spectrum to test and verify the geometric factors of the Omni-Direction Particle Detector (ODPD) on the Tiangong-1 (TG-1) and Tiangong-2 (TG-2) spacecraft. The TG spacecraft are experimental space laboratories and prototypes of the Chinese space station. The excellent agreement between the measured and reference spectra demonstrates that this test method can be used to quantitatively assess the quality of the instrument. Due to its simplicity, the method is faster and therefore more efficient than traditional full calibrations using an electron accelerator.
Sørensen, Lasse K; Olsen, Jeppe; Fleig, Timo
2011-06-07
A string-based coupled-cluster method of general excitation rank and with optimal scaling which accounts for special relativity within the four-component framework is presented. The method opens the way for the treatment of multi-reference problems through an active-space inspired single-reference based state-selective expansion of the model space. The evaluation of the coupled-cluster vector function is implemented by considering contractions of elementary second-quantized operators without setting up the amplitude equations explicitly. The capabilities of the new method are demonstrated in application to the electronic ground state of the bismuth monohydride molecule. In these calculations simulated multi-reference expansions with both doubles and triples excitations into the external space as well as the regular coupled-cluster hierarchy up to full quadruples excitations are compared. The importance of atomic outer core-correlation for obtaining accurate results is shown. Comparison to the non-relativistic framework is performed throughout to illustrate the additional work of the transition to the four-component relativistic framework both in implementation and application. Furthermore, an evaluation of the highest order scaling for general-order expansions is presented. © 2011 American Institute of Physics
Directory of Open Access Journals (Sweden)
Özkan Güner
2014-01-01
Full Text Available We apply the functional variable method, exp-function method, and (G′/G-expansion method to establish the exact solutions of the nonlinear fractional partial differential equation (NLFPDE in the sense of the modified Riemann-Liouville derivative. As a result, some new exact solutions for them are obtained. The results show that these methods are very effective and powerful mathematical tools for solving nonlinear fractional equations arising in mathematical physics. As a result, these methods can also be applied to other nonlinear fractional differential equations.
Yatsenko, Vitaliy; Falchenko, Iurii; Fedorchuk, Viktor; Petrushynets, Lidiia
2016-07-01
This report focuses on the results of the EU project "Superlight-weight thermal protection system for space application (LIGHT-TPS)". The bottom line is an analysis of influence of the free space environment on the superlight-weight thermal protection system (TPS). This report focuses on new methods that based on the following models: synergetic, physical, and computational. This report concentrates on four approaches. The first concerns the synergetic approach. The synergetic approach to the solution of problems of self-controlled synthesis of structures and creation of self-organizing technologies is considered in connection with the super-problem of creation of materials with new functional properties. Synergetics methods and mathematical design are considered according to actual problems of material science. The second approach describes how the optimization methods can be used to determine material microstructures with optimized or targeted properties. This technique enables one to find unexpected microstructures with exotic behavior (e.g., negative thermal expansion coefficients). The third approach concerns the dynamic probabilistic risk analysis of TPS l elements with complex characterizations for damages using a physical model of TPS system and a predictable level of ionizing radiation and space weather. Focusing is given mainly on the TPS model, mathematical models for dynamic probabilistic risk assessment and software for the modeling and prediction of the influence of the free space environment. The probabilistic risk assessment method for TPS is presented considering some deterministic and stochastic factors. The last approach concerns results of experimental research of the temperature distribution on the surface of the honeycomb sandwich panel size 150 x 150 x 20 mm at the diffusion welding in vacuum are considered. An equipment, which provides alignment of temperature fields in a product for the formation of equal strength of welded joints is
Li, Zhifei; Qin, Dongliang; Yang, Feng
2014-01-01
In defense related programs, the use of capability-based analysis, design, and acquisition has been significant. In order to confront one of the most challenging features of a huge design space in capability based analysis (CBA), a literature review of design space exploration was first examined. Then, in the process of an aerospace system of systems design space exploration, a bilayer mapping method was put forward, based on the existing experimental and operating data. Finally, the feasibility of the foregoing approach was demonstrated with an illustrative example. With the data mining RST (rough sets theory) and SOM (self-organized mapping) techniques, the alternative to the aerospace system of systems architecture was mapping from P-space (performance space) to C-space (configuration space), and then from C-space to D-space (design space), respectively. Ultimately, the performance space was mapped to the design space, which completed the exploration and preliminary reduction of the entire design space. This method provides a computational analysis and implementation scheme for large-scale simulation.
Energy Technology Data Exchange (ETDEWEB)
Trias, Miquel [Departament de Fisica, Universitat de les Illes Balears, Cra. Valldemossa Km. 7.5, E-07122 Palma de Mallorca (Spain); Vecchio, Alberto; Veitch, John, E-mail: miquel.trias@uib.e, E-mail: av@star.sr.bham.ac.u, E-mail: jveitch@star.sr.bham.ac.u [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)
2009-10-21
Bayesian analysis of Laser Interferometer Space Antenna (LISA) data sets based on Markov chain Monte Carlo methods has been shown to be a challenging problem, in part due to the complicated structure of the likelihood function consisting of several isolated local maxima that dramatically reduces the efficiency of the sampling techniques. Here we introduce a new fully Markovian algorithm, a delayed rejection Metropolis-Hastings Markov chain Monte Carlo method, to efficiently explore these kind of structures and we demonstrate its performance on selected LISA data sets containing a known number of stellar-mass binary signals embedded in Gaussian stationary noise.
A new time–space domain high-order finite-difference method for the acoustic wave equation
Liu, Yang
2009-12-01
A new unified methodology was proposed in Finkelstein and Kastner (2007) [39] to derive spatial finite-difference (FD) coefficients in the joint time-space domain to reduce numerical dispersion. The key idea of this method is that the dispersion relation is completely satisfied at several designated frequencies. We develop this new time-space domain FD method further for 1D, 2D and 3D acoustic wave modeling using a plane wave theory and the Taylor series expansion. New spatial FD coefficients are frequency independent though they lead to a frequency dependent numerical solution. We prove that the modeling accuracy is 2nd-order when the conventional (2 M)th-order space domain FD and the 2nd-order time domain FD stencils are directly used to solve the acoustic wave equation. However, under the same discretization, the new 1D method can reach (2 M)th-order accuracy and is always stable. The 2D method can reach (2 M)th-order accuracy along eight directions and has better stability. Similarly, the 3D method can reach (2 M)th-order accuracy along 48 directions and also has better stability than the conventional FD method. The advantages of the new method are also demonstrated by the results of dispersion analysis and numerical modeling of acoustic wave equation for homogeneous and inhomogeneous acoustic models. In addition, we study the influence of the FD stencil length on numerical modeling for 1D inhomogeneous media, and derive an optimal FD stencil length required to balance the accuracy and efficiency of modeling. A new time-space domain high-order staggered-grid FD method for the 1D acoustic wave equation with variable densities is also developed, which has similar advantages demonstrated by dispersion analysis, stability analysis and modeling experiments. The methodology presented in this paper can be easily extended to solve similar partial difference equations arising in other fields of science and engineering. © 2009 Elsevier Inc.
Zhang, Xi-Cheng; Riordan, Jenifer Ann; Sun, Feng-Guo
2000-08-29
Apparatus and methods for characterizing free-space electromagnetic energy, and in particular, apparatus/method suitable for real-time two-dimensional far-infrared imaging applications are presented. The sensing technique is based on a non-linear coupling between a low-frequency electric (or magnetic) field and a laser beam in an electro-optic (or magnetic-optic) crystal. In addition to a practical counter-propagating sensing technique, a co-linear approach is described which provides longer radiated field-optical beam interaction length, thereby making imaging applications practical.
A Comparative of Nuclear Technology and Direct Energy Conversion Methods for Space Power Systems
1997-06-01
0.2 I I I 0 200 400 600 800 Temperature (0CQ Figure 2-7. Semiconductor FOM. From ( Gulp , 1979). 17 The fundamental components of a thermionic generator...in. dian . ś • Ceramic insulator ’-Collector 0.010 to 0.015-in. "’’Tube for introducing Spacers brazed to spacing cesium vapor into Collector to...reactor core. Each fuel rod was encased in a ceramic -lined, Hastelloy cylinder. Liquid metal from the primary loop passed through a plenum chamber at the
Vector space methods of photometric analysis - Applications to O stars and interstellar reddening
Massa, D.; Lillie, C. F.
1978-01-01
A multivariate vector-space formulation of photometry is developed which accounts for error propagation. An analysis of uvby and H-beta photometry of O stars is presented, with attention given to observational errors, reddening, general uvby photometry, early stars, and models of O stars. The number of observable parameters in O-star continua is investigated, the way these quantities compare with model-atmosphere predictions is considered, and an interstellar reddening law is derived. It is suggested that photospheric expansion affects the formation of the continuum in at least some O stars.
Cheng, Rongjun; Sun, Fengxin; Wei, Qi; Wang, Jufeng
2018-02-01
Space-fractional advection-dispersion equation (SFADE) can describe particle transport in a variety of fields more accurately than the classical models of integer-order derivative. Because of nonlocal property of integro-differential operator of space-fractional derivative, it is very challenging to deal with fractional model, and few have been reported in the literature. In this paper, a numerical analysis of the two-dimensional SFADE is carried out by the element-free Galerkin (EFG) method. The trial functions for the SFADE are constructed by the moving least-square (MLS) approximation. By the Galerkin weak form, the energy functional is formulated. Employing the energy functional minimization procedure, the final algebraic equations system is obtained. The Riemann-Liouville operator is discretized by the Grünwald formula. With center difference method, EFG method and Grünwald formula, the fully discrete approximation schemes for SFADE are established. Comparing with exact results and available results by other well-known methods, the computed approximate solutions are presented in the format of tables and graphs. The presented results demonstrate the validity, efficiency and accuracy of the proposed techniques. Furthermore, the error is computed and the proposed method has reasonable convergence rates in spatial and temporal discretizations.
Directory of Open Access Journals (Sweden)
Sayangku Nor Ariati Mohamad Aris
2014-01-01
Full Text Available Three-dimensional structure of thermostable lipase is much sought after nowadays as it is important for industrial application mainly found in the food, detergent, and pharmaceutical sectors. Crystallization utilizing the counter diffusion method in space was performed with the aim to obtain high resolution diffracting crystals with better internal order to improve the accuracy of the structure. Thermostable T1 lipase enzyme has been crystallized in laboratory on earth and also under microgravity condition aboard Progress spacecraft to the ISS in collaboration with JAXA (Japanese Aerospace Exploration Agency. This study is conducted with the aims of improving crystal packing and structure resolution. The diffraction data set for ground grown crystal was collected to 1.3 Å resolution and belonged to monoclinic C2 space group with unit cell parameters a=117.40 Å, b=80.95 Å, and c=99.81 Å, whereas the diffraction data set for space grown crystal was collected to 1.1 Å resolution and belonged to monoclinic C2 space group with unit cell parameters a=117.31 Å, b=80.85 Å, and c=99.81 Å. The major difference between the two crystal growth systems is the lack of convection and sedimentation in microgravity environment resulted in the growth of much higher quality crystals of T1 lipase.
Burst suppression probability algorithms: state-space methods for tracking EEG burst suppression
Chemali, Jessica; Ching, ShiNung; Purdon, Patrick L.; Solt, Ken; Brown, Emery N.
2013-10-01
Objective. Burst suppression is an electroencephalogram pattern in which bursts of electrical activity alternate with an isoelectric state. This pattern is commonly seen in states of severely reduced brain activity such as profound general anesthesia, anoxic brain injuries, hypothermia and certain developmental disorders. Devising accurate, reliable ways to quantify burst suppression is an important clinical and research problem. Although thresholding and segmentation algorithms readily identify burst suppression periods, analysis algorithms require long intervals of data to characterize burst suppression at a given time and provide no framework for statistical inference. Approach. We introduce the concept of the burst suppression probability (BSP) to define the brain's instantaneous propensity of being in the suppressed state. To conduct dynamic analyses of burst suppression we propose a state-space model in which the observation process is a binomial model and the state equation is a Gaussian random walk. We estimate the model using an approximate expectation maximization algorithm and illustrate its application in the analysis of rodent burst suppression recordings under general anesthesia and a patient during induction of controlled hypothermia. Main result. The BSP algorithms track burst suppression on a second-to-second time scale, and make possible formal statistical comparisons of burst suppression at different times. Significance. The state-space approach suggests a principled and informative way to analyze burst suppression that can be used to monitor, and eventually to control, the brain states of patients in the operating room and in the intensive care unit.
3D VIRTUAL RECONSTRUCTION OF AN URBAN HISTORICAL SPACE: A CONSIDERATION ON THE METHOD
Directory of Open Access Journals (Sweden)
M. Galizia
2012-09-01
Full Text Available Urban historical spaces are often characterized by a variety of shapes, geometries, volumes, materials. Their virtual reconstruction requires a critical approach in terms of acquired data's density, timing optimization, final product's quality and slimness. The research team has focused its attention on the study on Francesco Neglia square (previously named Saint Thomas square in Enna. This square is an urban space fronted by architectures which present historical and stylistic differences. For example you can find the Saint Thomas'church belfry (in aragounese-catalan stile dated XIV century and the porch, the Anime Sante baroque's church (XVII century, Saint Mary of the Grace's nunnery (XVIII century and as well as some civil buildings of minor importance built in the mid twentieth century. The research has compared two different modeling tools approaches: the first one is based on the construction of triangulated surfaces which are segmented and simplified; the second one is based on the detection of surfaces geometrical features, the extraction of the more significant profiles by using a software dedicated to the elaboration of cloud points and the subsequent mathematical reconstruction by using a 3d modelling software. The following step was aimed to process the virtual reconstruction of urban scene by assembling the single optimized models. This work highlighted the importance of the image of the operator and of its cultural contribution, essential to recognize geometries which generates surfaces in order to create high quality semantic models.
D Virtual Reconstruction of AN Urban Historical Space: a Consideration on the Method
Galizia, M.; Santagati, C.
2011-09-01
Urban historical spaces are often characterized by a variety of shapes, geometries, volumes, materials. Their virtual reconstruction requires a critical approach in terms of acquired data's density, timing optimization, final product's quality and slimness. The research team has focused its attention on the study on Francesco Neglia square (previously named Saint Thomas square) in Enna. This square is an urban space fronted by architectures which present historical and stylistic differences. For example you can find the Saint Thomas'church belfry (in aragounese-catalan stile dated XIV century) and the porch, the Anime Sante baroque's church (XVII century), Saint Mary of the Grace's nunnery (XVIII century) and as well as some civil buildings of minor importance built in the mid twentieth century. The research has compared two different modeling tools approaches: the first one is based on the construction of triangulated surfaces which are segmented and simplified; the second one is based on the detection of surfaces geometrical features, the extraction of the more significant profiles by using a software dedicated to the elaboration of cloud points and the subsequent mathematical reconstruction by using a 3d modelling software. The following step was aimed to process the virtual reconstruction of urban scene by assembling the single optimized models. This work highlighted the importance of the image of the operator and of its cultural contribution, essential to recognize geometries which generates surfaces in order to create high quality semantic models.
Investigating plasma-rotation methods for the Space-Plasma Physics Campaign at UCLA's BAPSF.
Finnegan, S. M.; Koepke, M. E.; Reynolds, E. W.
2006-10-01
In D'Angelo et al., JGR 79, 4747 (1974), rigid-body ExB plasma flow was inferred from parabolic floating-potential profiles produced by a spiral ionizing surface. Here, taking a different approach, we report effects on barium-ion azimuthal-flow profiles using either a non-emissive or emissive spiral end-electrode in the WVU Q-machine. Neither electrode produced a radially-parabolic space-potential profile. The emissive spiral, however, generated controllable, radially-parabolic structure in the floating potential, consistent with a second population of electrons having a radially-parabolic parallel-energy profile. Laser-induced-fluorescence measurements of spatially resolved, azimuthal-velocity distribution functions show that, for a given flow profile, the diamagnetic drift of hot (>>0.2eV) ions overwhelms the ExB-drift contribution. Our experiments constitute a first attempt at producing controllable, rigid-body, ExB plasma flow for future experiments on the LArge-Plasma-Device (LAPD), as part of the Space-Plasma Physics Campaign (at UCLA's BAPSF).
Space-time adaptive solution of inverse problems with the discrete adjoint method
Alexe, Mihai; Sandu, Adrian
2014-08-01
This paper develops a framework for the construction and analysis of discrete adjoint sensitivities in the context of time dependent, adaptive grid, adaptive step models. Discrete adjoints are attractive in practice since they can be generated with low effort using automatic differentiation. However, this approach brings several important challenges. The space-time adjoint of the forward numerical scheme may be inconsistent with the continuous adjoint equations. A reduction in accuracy of the discrete adjoint sensitivities may appear due to the inter-grid transfer operators. Moreover, the optimization algorithm may need to accommodate state and gradient vectors whose dimensions change between iterations. This work shows that several of these potential issues can be avoided through a multi-level optimization strategy using discontinuous Galerkin (DG) hp-adaptive discretizations paired with Runge-Kutta (RK) time integration. We extend the concept of dual (adjoint) consistency to space-time RK-DG discretizations, which are then shown to be well suited for the adaptive solution of time-dependent inverse problems. Furthermore, we prove that DG mesh transfer operators on general meshes are also dual consistent. This allows the simultaneous derivation of the discrete adjoint for both the numerical solver and the mesh transfer logic with an automatic code generation mechanism such as algorithmic differentiation (AD), potentially speeding up development of large-scale simulation codes. The theoretical analysis is supported by numerical results reported for a two-dimensional non-stationary inverse problem.
A method of evaluating efficiency during space-suited work in a neutral buoyancy environment
Greenisen, Michael C.; West, Phillip; Newton, Frederick K.; Gilbert, John H.; Squires, William G.
1991-01-01
The purpose was to investigate efficiency as related to the work transmission and the metabolic cost of various extravehicular activity (EVA) tasks during simulated microgravity (whole body water immersion) using three space suits. Two new prototype space station suits, AX-5 and MKIII, are pressurized at 57.2 kPa and were tested concurrently with the operationally used 29.6 kPa shuttle suit. Four male astronauts were asked to perform a fatigue trial on four upper extremity exercises during which metabolic rate and work output were measured and efficiency was calculated in each suit. The activities were selected to simulate actual EVA tasks. The test article was an underwater dynamometry system to which the astronauts were secured by foot restraints. All metabolic data was acquired, calculated, and stored using a computerized indirect calorimetry system connected to the suit ventilation/gas supply control console. During the efficiency testing, steady state metabolic rate could be evaluated as well as work transmitted to the dynamometer. Mechanical efficiency could then be calculated for each astronaut in each suit performing each movement.
International Nuclear Information System (INIS)
Pushkarskij, A.S.; Okhotin, A.S.
1975-01-01
The present state and prospects for development of space programmes of the USSR and the USA, as well as of a number of countries of Europe and Asia, and of international programmes, provide for a steady rise in the need for on-board energy supply of space objects. The solution of both scientific and technical problems, as well as of the problem of survival on-board the spacecraft, depends to a considerable extent upon such energy supplies. Nuclear sources of heat such as reactors or radioisotopes and energy converters, which feature a number of advantages for autonomous power supply over solar cells and fuel cells, have already been operated, or been designed and developed for use as on-board power sources for the execution of some space programmes. Major difficulties are now presented by the problem of developing converter units for space applications that would be both reliable in operation and economical with regard to their power and weight. The review discusses methods for the conversion of nuclear heat to electricity in spaceborne power systems. For a better understanding of processes occurring in dynamic converters, namely, gas-turbine and vapour-turbine ones, brief consideration is given to their thermodynamic cycles, and, in the case of direct conversion methods such as thermoelectric, thermionic and magnetohydrodynamic ones, to the physical principles underlying such methods. Conversion diagrams are considered, basic characteristics of the existing or projected nuclear power plants for space applications are combined in tables, and an attempt is made to compare these characteristics to determine the place of such power plants in space power engineering. The review is intended for large sections of scientists, engineers and state employees concerned with this problem, and aims at presenting in condensed and general form the current state of the problem. The bibliography has been compiled to cover the major works published during the last five years on the
Kimoto, K.; Hirose, S.
2002-05-01
This paper presents a boundary integral equation method for 3D ultrasonic scattering problems in a fluid-loaded elastic half space. Since full scale of numerical calculation using finite element or boundary element method is still very expensive, we formulate a boundary integral equation for the scattered field, which is amenable to numerical treatment. In order to solve the problem using the integral equation, however, the wave field without scattering objects, so-called free field need to be given in advance. We calculate the free field by the plane wave spectral method where the asymptotic approximation is introduced for computational efficiency. To show the efficiency of our method, scattering by a spherical cavity near fluid-solid interface is solved and the validity of the results is discussed.
Cao, Ying; Yang, Lin; He, Zichang
2017-01-01
Specific emitter identification plays an important role in contemporary military affairs. However, most of the existing specific emitter identification methods haven’t taken into account the processing of uncertain information. Therefore, this paper proposes a time–space domain information fusion method based on Dempster–Shafer evidence theory, which has the ability to deal with uncertain information in the process of specific emitter identification. In this paper, radars will generate a group of evidence respectively based on the information they obtained, and our main task is to fuse the multiple groups of evidence to get a reasonable result. Within the framework of recursive centralized fusion model, the proposed method incorporates a correlation coefficient, which measures the relevance between evidence and a quantum mechanical approach, which is based on the parameters of radar itself. The simulation results of an illustrative example demonstrate that the proposed method can effectively deal with uncertain information and get a reasonable recognition result. PMID:28846629
Jiang, Wen; Cao, Ying; Yang, Lin; He, Zichang
2017-08-28
Specific emitter identification plays an important role in contemporary military affairs. However, most of the existing specific emitter identification methods haven't taken into account the processing of uncertain information. Therefore, this paper proposes a time-space domain information fusion method based on Dempster-Shafer evidence theory, which has the ability to deal with uncertain information in the process of specific emitter identification. In this paper, radars will generate a group of evidence respectively based on the information they obtained, and our main task is to fuse the multiple groups of evidence to get a reasonable result. Within the framework of recursive centralized fusion model, the proposed method incorporates a correlation coefficient, which measures the relevance between evidence and a quantum mechanical approach, which is based on the parameters of radar itself. The simulation results of an illustrative example demonstrate that the proposed method can effectively deal with uncertain information and get a reasonable recognition result.
Non-parametric method for separating domestic hot water heating spikes and space heating
DEFF Research Database (Denmark)
Bacher, Peder; de Saint-Aubain, Philip Anton; Christiansen, Lasse Engbo
2016-01-01
In this paper a method for separating spikes from a noisy data series, where the data change and evolve over time, is presented. The method is applied on measurements of the total heat load for a single family house. It relies on the fact that the domestic hot water heating is a process generatin...
Mission from Mars - a method for exploring user requirements for children in a narrative space
DEFF Research Database (Denmark)
Dindler, Christian; Ludvigsen, Martin; Lykke-Olesen, Andreas
2005-01-01
In this paper a particular design method is propagated as a supplement to existing descriptive approaches to current practice studies especially suitable for gathering requirements for the design of children's technology. The Mission from Mars method was applied during the design of an electronic...
Directory of Open Access Journals (Sweden)
Guoxu Wang
2017-02-01
Full Text Available A well-performed core power control to track load changes is crucial in pressurized water reactor (PWR nuclear power stations. It is challenging to keep the core power stable at the desired value within acceptable error bands for the safety demands of the PWR due to the sensitivity of nuclear reactors. In this paper, a state-space model predictive control (MPC method was applied to the control of the core power. The model for core power control was based on mathematical models of the reactor core, the MPC model, and quadratic programming (QP. The mathematical models of the reactor core were based on neutron dynamic models, thermal hydraulic models, and reactivity models. The MPC model was presented in state-space model form, and QP was introduced for optimization solution under system constraints. Simulations of the proposed state-space MPC control system in PWR were designed for control performance analysis, and the simulation results manifest the effectiveness and the good performance of the proposed control method for core power control.
Energy Technology Data Exchange (ETDEWEB)
Wang, Guo Xu; Wu, Jie; Zeng, Bifan; Wu, Wangqiang; Ma, Xiao Qian [School of Electric Power, South China University of Technology, Guangzhou (China); Xu, Zhibin [Electric Power Research Institute of Guangdong Power Grid Corporation, Guangzhou (China)
2017-02-15
A well-performed core power control to track load changes is crucial in pressurized water reactor (PWR) nuclear power stations. It is challenging to keep the core power stable at the desired value within acceptable error bands for the safety demands of the PWR due to the sensitivity of nuclear reactors. In this paper, a state-space model predictive control (MPC) method was applied to the control of the core power. The model for core power control was based on mathematical models of the reactor core, the MPC model, and quadratic programming (QP). The mathematical models of the reactor core were based on neutron dynamic models, thermal hydraulic models, and reactivity models. The MPC model was presented in state-space model form, and QP was introduced for optimization solution under system constraints. Simulations of the proposed state-space MPC control system in PWR were designed for control performance analysis, and the simulation results manifest the effectiveness and the good performance of the proposed control method for core power control.
Roberts, Brenden; Vidick, Thomas; Motrunich, Olexei I.
2017-12-01
The success of polynomial-time tensor network methods for computing ground states of certain quantum local Hamiltonians has recently been given a sound theoretical basis by Arad et al. [Math. Phys. 356, 65 (2017), 10.1007/s00220-017-2973-z]. The convergence proof, however, relies on "rigorous renormalization group" (RRG) techniques which differ fundamentally from existing algorithms. We introduce a practical adaptation of the RRG procedure which, while no longer theoretically guaranteed to converge, finds matrix product state ansatz approximations to the ground spaces and low-lying excited spectra of local Hamiltonians in realistic situations. In contrast to other schemes, RRG does not utilize variational methods on tensor networks. Rather, it operates on subsets of the system Hilbert space by constructing approximations to the global ground space in a treelike manner. We evaluate the algorithm numerically, finding similar performance to density matrix renormalization group (DMRG) in the case of a gapped nondegenerate Hamiltonian. Even in challenging situations of criticality, large ground-state degeneracy, or long-range entanglement, RRG remains able to identify candidate states having large overlap with ground and low-energy eigenstates, outperforming DMRG in some cases.
Directory of Open Access Journals (Sweden)
Zeqing Liu
2006-01-01
Full Text Available We investigate the equivalence between the convergences of the Mann iteration method and the Ishikawa iteration method with errors for demicontinuous φ-strongly accretive operators in uniformly smooth Banach spaces. A related result deals with the equivalence of the Mann iteration method and the Ishikawa iteration method for φ-pseudocontractive operators in nonempty closed convex subsets of uniformly smooth Banach spaces. The results presented in this paper extend and improve the corresponding results in the literature.
Berman, Gennady P [Los Alamos, NM; Bishop, Alan R [Los Alamos, NM; Nguyen, Dinh C [Los Alamos, NM; Chernobrod, Boris M [Santa Fe, NM; Gorshkov, Vacheslav N [Kiev, UA
2009-10-13
A high-speed (Gbps), free space optical communication system is based on spectral encoding of radiation from a wide band light source, such as a laser. By using partially coherent laser beams in combination with a relatively slow photosensor, scintillations can be suppressed by orders of magnitude for distances of more than 10 km. To suppress the intensity fluctuations due to atmospheric turbulence, a source with partial transverse coherence in combination with slow response time photodetector is used. Information is encoded in the spectral domain of a wideband optical source by modulation of spectral amplitudes. A non-coherent light source with wide spectrum (an LED, for example) may be used for high-speed communication over short (less than about a mile) distances.
Hybrid methods for accretive variational inequalities involving pseudocontractions in Banach spaces
Directory of Open Access Journals (Sweden)
Chen Rudong
2011-01-01
Full Text Available Abstract We use strongly pseudocontractions to regularize a class of accretive variational inequalities in Banach spaces, where the accretive operators are complements of pseudocontractions and the solutions are sought in the set of fixed points of another pseudocontraction. In this paper, we consider an implicit scheme that can be used to find a solution of a class of accretive variational inequalities. Our results improve and generalize some recent results of Yao et al. (Fixed Point Theory Appl, doi:10.1155/2011/180534, 2011 and Lu et al. (Nonlinear Anal, 71(3-4, 1032-1041, 2009. 2000 Mathematics subject classification 47H05; 47H09; 65J15
Choi, Michael K.
2014-01-01
A thermal design concept of attaching the thermoelectric cooler (TEC) hot side directly to the radiator and maximizing the number of TECs to cool multiple detectors in space is presented. It minimizes the temperature drop between the TECs and radiator. An ethane constant conductance heat pipe transfers heat from the detectors to a TEC cold plate which the cold side of the TECs is attached to. This thermal design concept minimizes the size of TEC heat rejection systems. Hence it reduces the problem of accommodating the radiator within a required envelope. It also reduces the mass of the TEC heat rejection system. Thermal testing of a demonstration unit in vacuum verified the thermal performance of the thermal design concept.
Stabilities of Cubic Mappings in Various Normed Spaces: Direct and Fixed Point Methods
Directory of Open Access Journals (Sweden)
H. Azadi Kenary
2012-01-01
Full Text Available In 1940 and 1964, Ulam proposed the general problem: “When is it true that by changing a little the hypotheses of a theorem one can still assert that the thesis of the theorem remains true or approximately true?”. In 1941, Hyers solved this stability problem for linear mappings. According to Gruber (1978 this kind of stability problems are of the particular interest in probability theory and in the case of functional equations of different types. In 1981, Skof was the first author to solve the Ulam problem for quadratic mappings. In 1982–2011, J. M. Rassias solved the above Ulam problem for linear and nonlinear mappings and established analogous stability problems even on restricted domains. The purpose of this paper is the generalized Hyers-Ulam stability for the following cubic functional equation: (++(−=(++(−+2(3−(,≥2 in various normed spaces.
A definition of distance and method of making space-time measurements
International Nuclear Information System (INIS)
Brisson, D.W.
1980-01-01
The paper explores an extended definition of the absolute value of a complex number and thus a new definition of distance. This new definition, called the nabsolute value of a complex number, is (Z) where Z = (a or ia) + (b or ib), so that (Z) is equivalent to [α 2 + β 2 ]sup(1/2), and α = a or ia, β = b or ib. This is shown on a superimposed X,Y plot and iX,iY plot so that four dimensions are represented in a plane. The application of this scheme to space-time measurement is then identified with the Minkowski Plane which has identical properties with the complex plane, with this new interpretation of the absolute value of a complex number. (Auth.)
Method for the control of NOx emissions in long-range space travel
Xu, X. H.; Shi, Y.; Liu, S. H.; Wang, H. P.; Chang, S. G.; Fisher, J. W.; Pisharody, S.; Moran, M.; Wignarajah, K.
2003-01-01
The wheat straw, an inedible biomass that can be continuously produced in a space vehicle has been used to produce activated carbon for effective control of NOx emissions from the incineration of wastes. The optimal carbonization temperature of wheat straw was found to be around 600 degrees C when a burnoff of 67% was observed. The BET surface area of the activated carbon produced from the wheat straw reached as high as 300 m2/g. The presence of oxygen in flue gas is essential for effective adsorption of NO by activated carbon. On the contrary, water vapor inhibits the adsorption efficiency of NO. Consequently, water vapor in flue gas should be removed by drying agents before adsorption to ensure high NO adsorption efficiency. All of the NO in the flue gas was removed for more than 2 h by the activated carbons when 10% oxygen was present and the ratio of carbon weight to the flue gas flow rate (W/F) was 30 g min/L, with a contact time of 10.2 s. All of NO was reduced to N2 by the activated carbon at 450 degrees C with a W/F ratio of 15 g min/L and a contact time of 5.1 s. Reduction of the adsorbed NO also regenerated the activated carbon, and the regenerated activated carbon exhibited an improved NO adsorption efficiency. However, the reduction of the adsorbed NO resulted in a loss of carbon which was determined to be about 0.99% of the activated carbon per cycle of regeneration. The sufficiency of the amount of wheat straw in providing the activated carbon based on a six-person crew, such as the mission planned for Mars, has been determined. This novel approach for the control of NOx emissions is sustainable in a closed system such as the case in space travel. It is simple to operate and is functional under microgravity environment.
Wang, Xiao-Yen; Chow, Chuen-Yen; Chang, Sin-Chung
1995-01-01
The existing 2-D alpha-mu scheme and alpha-epsilon scheme based on the method of space-time conservation element and solution element, which were constructed for solving the linear 2-D unsteady advection-diffusion equation and unsteady advection equation, respectively, are tested. Also, the alpha-epsilon scheme is modified to become the V-E scheme for solving the nonlinear 2-D inviscid Burgers equation. Numerical solutions of six test problems are presented in comparison with their exact solutions or numerical solutions obtained by traditional finite-difference or finite-element methods. It is demonstrated that the 2-D alpha-mu, alpha-epsilon, and nu-epsilon schemes can be used to obtain numerical results which are more accurate than those based on some of the traditional methods but without using any artificial tuning in the computation. Similar to the previous 1-D test problems, the high accuracy and simplicity features of the space-time conservation element and solution element method have been revealed again in the present 2-D test results.
Measuring the W-Boson mass at a hadron collider: a study of phase-space singularity methods
De Rújula, A
2011-01-01
The traditional method to measure the W-Boson mass at a hadron collider (more precisely, its ratio to the Z-mass) utilizes the distributions of three variables in events where the W decays into an electron or a muon: the charged-lepton transverse momentum, the missing transverse energy and the transverse mass of the lepton pair. We study the putative advantages of the additional measurement of a fourth variable: an improved phase-space singularity mass. This variable is statistically optimal, and simultaneously exploits the longitudinal- and transverse-momentum distributions of the charged lepton. Though the process we discuss is one of the simplest realistic ones involving just one unobservable particle, it is fairly non-trivial and constitutes a good "training" example for the scrutiny of phenomena involving invisible objects. Our graphical analysis of the phase space is akin to that of a Dalitz plot, extended to such processes.
Yang, Haijian
2016-07-26
Fully implicit methods are drawing more attention in scientific and engineering applications due to the allowance of large time steps in extreme-scale simulations. When using a fully implicit method to solve two-phase flow problems in porous media, one major challenge is the solution of the resultant nonlinear system at each time step. To solve such nonlinear systems, traditional nonlinear iterative methods, such as the class of the Newton methods, often fail to achieve the desired convergent rate due to the high nonlinearity of the system and/or the violation of the boundedness requirement of the saturation. In the paper, we reformulate the two-phase model as a variational inequality that naturally ensures the physical feasibility of the saturation variable. The variational inequality is then solved by an active-set reduced-space method with a nonlinear elimination preconditioner to remove the high nonlinear components that often causes the failure of the nonlinear iteration for convergence. To validate the effectiveness of the proposed method, we compare it with the classical implicit pressure-explicit saturation method for two-phase flow problems with strong heterogeneity. The numerical results show that our nonlinear solver overcomes the often severe limits on the time step associated with existing methods, results in superior convergence performance, and achieves reduction in the total computing time by more than one order of magnitude.
A New Design Method based on Cooperative Data Mining from Multi-Objective Design Space
Sugimura, Kazuyuki; Obayashi, Shigeru; Jeong, Shinkyu
We propose a new multi-objective parameter design method that uses the combination of the following data mining techniques: analysis of variance, self-organizing map, decision tree analysis, rough set theory, and association rule. This method first aims to improve multiple objective functions simultaneously using as much predominant main effects of different design variables as possible. Then it resolves the remaining conflictions between the objective functions using predominant interaction effects of design variables. The key to realizing this method is the obtaining of various design rules that quantitatively relate levels of design variables to levels of objective functions. Based on comparative studies of data mining techniques, the systematic processes for obtaining these design rules have been clarified, and the points of combining data mining techniques have also been summarized. This method has been applied to a multi-objective robust optimization problem of an industrial fan, and the results show its superior capabilities for controlling parameters to traditional single-objective parameter design methods like the Taguchi method.
International Nuclear Information System (INIS)
Haeberlein, F.
2011-01-01
Reactive transport modelling is a basic tool to model chemical reactions and flow processes in porous media. A totally reduced multi-species reactive transport model including kinetic and equilibrium reactions is presented. A structured numerical formulation is developed and different numerical approaches are proposed. Domain decomposition methods offer the possibility to split large problems into smaller subproblems that can be treated in parallel. The class of Schwarz-type domain decomposition methods that have proved to be high-performing algorithms in many fields of applications is presented with a special emphasis on the geometrical viewpoint. Numerical issues for the realisation of geometrical domain decomposition methods and transmission conditions in the context of finite volumes are discussed. We propose and validate numerically a hybrid finite volume scheme for advection-diffusion processes that is particularly well-suited for the use in a domain decomposition context. Optimised Schwarz waveform relaxation methods are studied in detail on a theoretical and numerical level for a two species coupled reactive transport system with linear and nonlinear coupling terms. Well-posedness and convergence results are developed and the influence of the coupling term on the convergence behaviour of the Schwarz algorithm is studied. Finally, we apply a Schwarz waveform relaxation method on the presented multi-species reactive transport system. (author)
Chang, S. C.; Wang, X. Y.; Chow, C. Y.; Himansu, A.
1995-01-01
The method of space-time conservation element and solution element is a nontraditional numerical method designed from a physicist's perspective, i.e., its development is based more on physics than numerics. It uses only the simplest approximation techniques and yet is capable of generating nearly perfect solutions for a 2-D shock reflection problem used by Helen Yee and others. In addition to providing an overall view of the new method, we introduce a new concept in the design of implicit schemes, and use it to construct a highly accurate solver for a convection-diffusion equation. It is shown that, in the inviscid case, this new scheme becomes explicit and its amplification factors are identical to those of the Leapfrog scheme. On the other hand, in the pure diffusion case, its principal amplification factor becomes the amplification factor of the Crank-Nicolson scheme.
International Nuclear Information System (INIS)
Matausek, M.
1972-01-01
A new proposed method for solving the space-energy dependent spherical harmonics equations represents a methodological contribution to neutron transport theory. The proposed method was applied for solving the problem of spec-energy transport of fast and resonance neutrons in multi-zone, cylindrical y symmetric infinite reactor cell and is related to previously developed procedure for treating the thermal energy region. The advantages of this method are as follows: a unique algorithm was obtained for detailed determination of spatial and energy distribution of neutrons (from thermal to fast) in the reactor cell; these detailed distributions enable more precise calculations of criticality conditions, obtaining adequate multigroup data and better interpretation of experimental data; computing time is rather short
Directory of Open Access Journals (Sweden)
Lei Ma
2016-09-01
Full Text Available Object-based change detection (OBCD has recently been receiving increasing attention as a result of rapid improvements in the resolution of remote sensing data. However, some OBCD issues relating to the segmentation of high-resolution images remain to be explored. For example, segmentation units derived using different segmentation strategies, segmentation scales, feature space, and change detection methods have rarely been assessed. In this study, we have tested four common unsupervised change detection methods using different segmentation strategies and a series of segmentation scale parameters on two WorldView-2 images of urban areas. We have also evaluated the effect of adding extra textural and Normalized Difference Vegetation Index (NDVI information instead of using only spectral information. Our results indicated that change detection methods performed better at a medium scale than at a fine scale where close to the pixel size. Multivariate Alteration Detection (MAD always outperformed the other methods tested, at the same confidence level. The overall accuracy appeared to benefit from using a two-date segmentation strategy rather than single-date segmentation. Adding textural and NDVI information appeared to reduce detection accuracy, but the magnitude of this reduction was not consistent across the different unsupervised methods and segmentation strategies. We conclude that a two-date segmentation strategy is useful for change detection in high-resolution imagery, but that the optimization of thresholds is critical for unsupervised change detection methods. Advanced methods need be explored that can take advantage of additional textural or other parameters.
Energy Technology Data Exchange (ETDEWEB)
Darula, Stanislav; Kocifaj, Miroslav; Kittler, Richard [ICA, Slovak Academy of Sciences, Bratislava (Slovakia); Kundracik, Frantisek [Department of Experimental Physics, FMPI, Comenius University, Bratislava (Slovakia)
2010-12-15
To ensure comfort and healthy conditions in interior spaces the thermal, acoustics and daylight factors of the environment have to be considered in the building design. Due to effective energy performance in buildings the new technology and applications also in daylight engineering are sought such as tubular light guides. These allow the transport of natural light into the building core reducing energy consumption. A lot of installations with various geometrical and optical properties can be applied in real buildings. The simplest set of tubular light guide consists of a transparent cupola, direct tube with high reflected inner surface and a ceiling cover or diffuser redistributing light into the interior. Such vertical tubular guide is often used on flat roofs. When the roof construction is inclined a bend in the light guide system has to be installed. In this case the cupola is set on the sloped roof which collects sunlight and skylight from the seen part of the sky hemisphere as well as that reflected from the ground and opposite facades. In comparison with the vertical tube some additional light losses and distortions of the propagated light have to be expected in bended tubular light guides. Recently the theoretical model of light propagation was already published and its applications are presented in this study solving illuminance distributions on the ceiling cover interface and further illuminance distribution on the working plane in the interior. (author)
A novel method to optimize the wavelength for underwater free-space optical communications
Neuner, Burton; Pascoguin, B. Melvin
2014-10-01
Wirelessly transmitting large volumes of information at high data rates underwater is becoming increasingly important for such applications as environmental monitoring and petroleum exploration and maintenance. Underwater free-space optical (FSO) communication addresses the aforementioned need by providing wireless high-data-rate links. Visible light transmission through seawater typically peaks in the blue-green spectrum (475 nm-575 nm), but local clarity conditions, which are dynamic, strongly influence the actual maximum. We describe the development of a new laser-wavelength auto-selection algorithm and system for optimized underwater FSO communication. This system has the potential to improve underwater optical link reliability for high-data-rate communications. First, we describe the laser system and water tube setup for performing optical experiments. Next, we present research on recreating various seawater types (from clear to turbid) in the laboratory using particle suspensions and dye, which will enable wavelength-dependent transmission tests. Finally, we show experimental results from optical water tube tests, and describe the development of the autoselection algorithm.
Convergence of hybrid steepest descent method for variational inequalities in Banach spaces
International Nuclear Information System (INIS)
Chidume, C.E.; Chidume, C.O.; Bashir, Ali
2007-07-01
Let E be a real q-uniformly smooth Banach space with constant d q , q ≥ 2. Let T : E → E and G : E → E be a nonexpansive map and an η-strongly accretive map which is also κ - Lipschitzian, respectively. Let {λ n } be a real sequence in [0, 1] satisfying some appropriate conditions. For δ element of (0, ( q η/d q κ q ) q-1 ), define a sequence { x n } iteratively in E by x 0 element of E, x n+1 = T λ n+1 x n = Tx n - δ λ n+1 G(Tx n ), n ≥ 0. Then, {x n } converges strongly to the unique solution x* of the variational inequality problem VI(G,K) (search for x* element of K such that q (y - x*)> ≥ 0 for all y element of K), where K := Fix(T) { x element of E : Tx = x} ≠ 0. A convergence theorem related to fi nite family of nonexpansive maps is also proved. (author)
Zhang, Hua; Zeng, Luan
2017-11-01
Binocular stereoscopic vision can be used for space-based space targets near observation. In order to solve the problem that the traditional binocular vision system cannot work normally after interference, an online calibration method of binocular stereo measuring camera with self-reference is proposed. The method uses an auxiliary optical imaging device to insert the image of the standard reference object into the edge of the main optical path and image with the target on the same focal plane, which is equivalent to a standard reference in the binocular imaging optical system; When the position of the system and the imaging device parameters are disturbed, the image of the standard reference will change accordingly in the imaging plane, and the position of the standard reference object does not change. The camera's external parameters can be re-calibrated by the visual relationship of the standard reference object. The experimental results show that the maximum mean square error of the same object can be reduced from the original 72.88mm to 1.65mm when the right camera is deflected by 0.4 degrees and the left camera is high and low with 0.2° rotation. This method can realize the online calibration of binocular stereoscopic vision measurement system, which can effectively improve the anti - jamming ability of the system.
A method for evaluating bias in global measurements of CO_{2} total columns from space
Energy Technology Data Exchange (ETDEWEB)
Wunch, D.; Wennberg, P. O.; Toon, G. C.; Connor, B. J.; Fisher, B.; Osterman, G. B.; Frankenberg, C.; Mandrake, L.; O' Dell, C.; Ahonen, P.; Biraud, S. C.; Castano, R.; Cressie, N.; Crisp, D.; Deutscher, N. M.; Eldering, A.; Fisher, M. L.; Griffith, D. W. T.; Gunson, M.; Heikkinen, P.; Keppel-Aleks, G.; Kyrö, E.; Lindenmaier, R.; Macatangay, R.; Mendonca, J.; Messerschmidt, J.; Miller, C. E.; Morino, I.; Notholt, J.; Oyafuso, F. A.; Rettinger, M.; Robinson, J.; Roehl, C. M.; Salawitch, R. J.; Sherlock, V.; Strong, K.; Sussmann, R.; Tanaka, T.; Thompson, D. R.; Uchino, O.; Warneke, T.; Wofsy, S. C.
2011-01-01
We describe a method of evaluating systematic errors in measurements of total column dry-air mole fractions of CO{sub 2} (X{sub CO{sub 2}} ) from space, and we illustrate the method by applying it to the Atmospheric CO{sub 2} Observations from Space retrievals of the Greenhouse Gases Observing Satellite (ACOS-GOSAT) v2.8. The approach exploits the lack of large gradients in X{sub CO{sub 2}} south of 25{degree} S to identify large-scale offsets and other biases in the ACOS-GOSAT data with several retrieval parameters and errors in instrument calibration. We demonstrate the effectiveness of the method by comparing the ACOS-GOSAT data in the Northern Hemisphere with ground truth provided by the Total Carbon Column Observing Network (TCCON). We use the correlation between free-tropospheric temperature and X{sub CO{sub 2}} in the Northern Hemisphere to define a dynamically informed coincidence criterion between the ground-based TCCON measurements and the ACOS-GOSAT measurements. We illustrate that this approach provides larger sample sizes, hence giving a more robust comparison than one that simply uses time, latitude and longitude criteria. Our results show that the agreement with the TCCON data improves after accounting for the systematic errors. A preliminary evaluation of the improved v2.9 ACOS-GOSAT data is also discussed.
Guoxu Wang; Jie Wu; Bifan Zeng; Zhibin Xu; Wanqiang Wu; Xiaoqian Ma
2017-01-01
A well-performed core power control to track load changes is crucial in pressurized water reactor (PWR) nuclear power stations. It is challenging to keep the core power stable at the desired value within acceptable error bands for the safety demands of the PWR due to the sensitivity of nuclear reactors. In this paper, a state-space model predictive control (MPC) method was applied to the control of the core power. The model for core power control was based on mathematical models of the reacto...
Wang, Xiao-Yen; Chow, Chuen-Yen; Chang, Sin-Chung
1999-01-01
Test problems are used to examine the performance of several one-dimensional numerical schemes based on the space-time conservation and solution element (CE/SE) method. Investigated in this paper are the CE/SE schemes constructed previously for solving the linear unsteady advection-diffusion equation and the schemes derived here for solving the nonlinear viscous and inviscid Burgers equations. In comparison with the numerical solutions obtained using several traditional finite-difference schemes with similar accuracy, the CE/SE solutions display much lower numerical dissipation and dispersion errors.
Argatov, Ivan I.; Popov, Valentin L.
2016-08-01
The method of dimensionality reduction (MDR) is extended for the axisymmetric frictionless unilateral Hertz-type contact problem for a viscoelastic half-space and an arbitrary axisymmetric rigid indenter under the assumption that an arbitrarily evolving in time circular contact area remains singly connected during the whole process of indentation. In particular, the MDR is applied to study in detail the so-called rebound indentation problem, where the contact radius has a single maximum. It is shown that the obtained closed-form analytical solution for the rebound indentation displacement (recorded in the recovery phase, when the contact force vanishes) does not depend on the indenter shape.
Directory of Open Access Journals (Sweden)
YUE Chunyu
2017-03-01
Full Text Available A matching method of space-borne laser altimeter big footprint waveform and terrain based on cross cumulative residual entropy(CCRE is proposed. Firstly, the waveform data and digital surface model(DSM data are projected to the statistics domain, according to the terrain structure information of the waveform, where statistics signal vectors of the two data are in the same dimension. Then, the waveform data and DSM image are matched in the statistics domain with CCRE. Experiments show that the algorithm proposed is effective in waveform and terrain matching, and the matching accuracy is within 1 pixel.
Tang, Jiayu; Kayo, Issha; Takada, Masahiro
2011-09-01
We develop a maximum likelihood based method of reconstructing the band powers of the density and velocity power spectra at each wavenumber bin from the measured clustering features of galaxies in redshift space, including marginalization over uncertainties inherent in the small-scale, non-linear redshift distortion, the Fingers-of-God (FoG) effect. The reconstruction can be done assuming that the density and velocity power spectra depend on the redshift-space power spectrum having different angular modulations of μ with μ2n (n= 0, 1, 2) and that the model FoG effect is given as a multiplicative function in the redshift-space spectrum. By using N-body simulations and the halo catalogues, we test our method by comparing the reconstructed power spectra with the spectra directly measured from the simulations. For the spectrum of μ0 or equivalently the density power spectrum Pδδ(k), our method recovers the amplitudes to an accuracy of a few per cent up to k≃ 0.3 h Mpc-1 for both dark matter and haloes. For the power spectrum of μ2, which is equivalent to the density-velocity power spectrum Pδθ(k) in the linear regime, our method can recover, within the statistical errors, the input power spectrum for dark matter up to k≃ 0.2 h Mpc-1 and at both redshifts z= 0 and 1, if the adequate FoG model being marginalized over is employed. However, for the halo spectrum that is least affected by the FoG effect, the reconstructed spectrum shows greater amplitudes than the spectrum Pδθ(k) inferred from the simulations over a range of wavenumbers 0.05 ≤k≤ 0.3 h Mpc-1. We argue that the disagreement may be ascribed to a non-linearity effect that arises from the cross-bispectra of density and velocity perturbations. Using the perturbation theory and assuming Einstein gravity as in simulations, we derive the non-linear correction term to the redshift-space spectrum, and find that the leading-order correction term is proportional to μ2 and increases the μ2-power
DEFF Research Database (Denmark)
Enkovaara, J.; Rostgaard, Carsten; Mortensen, Jens Jørgen
2010-01-01
Electronic structure calculations have become an indispensable tool in many areas of materials science and quantum chemistry. Even though the Kohn-Sham formulation of the density-functional theory (DFT) simplifies the many-body problem significantly, one is still confronted with several numerical...... challenges. In this article we present the projector augmented-wave (PAW) method as implemented in the GPAW program package (https://wiki.fysik.dtu.dk/gpaw) using a uniform real-space grid representation of the electronic wavefunctions. Compared to more traditional plane wave or localized basis set...
Ebert, Marcelo R
2018-01-01
This book provides an overview of different topics related to the theory of partial differential equations. Selected exercises are included at the end of each chapter to prepare readers for the “research project for beginners” proposed at the end of the book. It is a valuable resource for advanced graduates and undergraduate students who are interested in specializing in this area. The book is organized in five parts: In Part 1 the authors review the basics and the mathematical prerequisites, presenting two of the most fundamental results in the theory of partial differential equations: the Cauchy-Kovalevskaja theorem and Holmgren's uniqueness theorem in its classical and abstract form. It also introduces the method of characteristics in detail and applies this method to the study of Burger's equation. Part 2 focuses on qualitative properties of solutions to basic partial differential equations, explaining the usual properties of solutions to elliptic, parabolic and hyperbolic equations for the archetypes...
Active vibration control using state space LQG and internal model control methods
DEFF Research Database (Denmark)
Mørkholt, Jakob; Elliott, S.J.
1998-01-01
Two ways of designing discrete time robust H2-controllers for feedback broadband active vibration control are compared through computer simulations. The methods are based on different models of disturbance and plant transfer functions, but yield controllers with identical properties. Two simple...... ways of introducing robustness into the H2-design are compared, and finally an efficient way of designing a practical IIR-controller is proposed....
Hu, Rui; Liu, Shutian; Li, Quhao
2017-05-20
For the development of a large-aperture space telescope, one of the key techniques is the method for designing the flexures for mounting the primary mirror, as the flexures are the key components. In this paper, a topology-optimization-based method for designing flexures is presented. The structural performances of the mirror system under multiple load conditions, including static gravity and thermal loads, as well as the dynamic vibration, are considered. The mirror surface shape error caused by gravity and the thermal effect is treated as the objective function, and the first-order natural frequency of the mirror structural system is taken as the constraint. The pattern repetition constraint is added, which can ensure symmetrical material distribution. The topology optimization model for flexure design is established. The substructuring method is also used to condense the degrees of freedom (DOF) of all the nodes of the mirror system, except for the nodes that are linked to the mounting flexures, to reduce the computation effort during the optimization iteration process. A potential optimized configuration is achieved by solving the optimization model and post-processing. A detailed shape optimization is subsequently conducted to optimize its dimension parameters. Our optimization method deduces new mounting structures that significantly enhance the optical performance of the mirror system compared to the traditional methods, which only focus on the parameters of existing structures. Design results demonstrate the effectiveness of the proposed optimization method.
Directory of Open Access Journals (Sweden)
Kravtsenyuk Olga V
2007-01-01
Full Text Available The possibility of improving the spatial resolution of diffuse optical tomograms reconstructed by the photon average trajectories (PAT method is substantiated. The PAT method recently presented by us is based on a concept of an average statistical trajectory for transfer of light energy, the photon average trajectory (PAT. The inverse problem of diffuse optical tomography is reduced to a solution of an integral equation with integration along a conditional PAT. As a result, the conventional algorithms of projection computed tomography can be used for fast reconstruction of diffuse optical images. The shortcoming of the PAT method is that it reconstructs the images blurred due to averaging over spatial distributions of photons which form the signal measured by the receiver. To improve the resolution, we apply a spatially variant blur model based on an interpolation of the spatially invariant point spread functions simulated for the different small subregions of the image domain. Two iterative algorithms for solving a system of linear algebraic equations, the conjugate gradient algorithm for least squares problem and the modified residual norm steepest descent algorithm, are used for deblurring. It is shown that a gain in spatial resolution can be obtained.
Mass change distribution inverted from space-borne gravimetric data using a Monte Carlo method
Zhou, X.; Sun, X.; Wu, Y.; Sun, W.
2017-12-01
Mass estimate plays a key role in using temporally satellite gravimetric data to quantify the terrestrial water storage change. GRACE (Gravity Recovery and Climate Experiment) only observes the low degree gravity field changes, which can be used to estimate the total surface density or equivalent water height (EWH) variation, with a limited spatial resolution of 300 km. There are several methods to estimate the mass variation in an arbitrary region, such as averaging kernel, forward modelling and mass concentration (mascon). Mascon method can isolate the local mass from the gravity change at a large scale through solving the observation equation (objective function) which represents the relationship between unknown masses and the measurements. To avoid the unreasonable local mass inverted from smoothed gravity change map, regularization has to be used in the inversion. We herein give a Markov chain Monte Carlo (MCMC) method to objectively determine the regularization parameter for the non-negative mass inversion problem. We first apply this approach to the mass inversion from synthetic data. Result show MCMC can effectively reproduce the local mass variation taking GRACE measurement error into consideration. We then use MCMC to estimate the ground water change rate of North China Plain from GRACE gravity change rate from 2003 to 2014 under a supposition of the continuous ground water loss in this region. Inversion result show that the ground water loss rate in North China Plain is 7.6±0.2Gt/yr during past 12 years which is coincident with that from previous researches.
Mechanisms of deterioration of nutrients. [freeze drying methods for space flight food
Karel, M.; Flink, J. M.
1974-01-01
Methods are reported by which freeze dried foods of improved quality will be produced. The applicability of theories of flavor retention has been demonstrated for a number of food polymers, both proteins and polysacchardies. Studies on the formation of structures during freeze drying have been continued for emulsified systems. Deterioration of organoleptic quality of freeze dried foods due to high temperature heating has been evaluated and improved procedures developed. The influence of water activity and high temperature on retention of model flavor materials and browning deterioration has been evaluated for model systems and food materials.
Geometric Methods for ATR: Shape Spaces, Metrics, Object/Image Relations, and Shapelets
2007-09-30
and only if Kr - 4 C L r - 3 C H r - l C r This fact and the incidence relations given in Theorem I, §5, Chapter VII of Hodge and Pedoe [4] give us our...Springer-Verlag, 1992. 4. W.V.D. Hodge and D. Pedoe , Methods of Algebraic Geometry, nos. 1, 2, and 3, in Mathematical Library Series, Cambridge...and Pedoe [5] give us our object-image relations. Theorem 2.4. Let Pi = (xi, yi, zi), 1 < i < r be an object configuration with corresponding matrix M
A novel weld seam detection method for space weld seam of narrow butt joint in laser welding
Shao, Wen Jun; Huang, Yu; Zhang, Yong
2018-02-01
Structured light measurement is widely used for weld seam detection owing to its high measurement precision and robust. However, there is nearly no geometrical deformation of the stripe projected onto weld face, whose seam width is less than 0.1 mm and without misalignment. So, it's very difficult to ensure an exact retrieval of the seam feature. This issue is raised as laser welding for butt joint of thin metal plate is widely applied. Moreover, measurement for the seam width, seam center and the normal vector of the weld face at the same time during welding process is of great importance to the welding quality but rarely reported. Consequently, a seam measurement method based on vision sensor for space weld seam of narrow butt joint is proposed in this article. Three laser stripes with different wave length are project on the weldment, in which two red laser stripes are designed and used to measure the three dimensional profile of the weld face by the principle of optical triangulation, and the third green laser stripe is used as light source to measure the edge and the centerline of the seam by the principle of passive vision sensor. The corresponding image process algorithm is proposed to extract the centerline of the red laser stripes as well as the seam feature. All these three laser stripes are captured and processed in a single image so that the three dimensional position of the space weld seam can be obtained simultaneously. Finally, the result of experiment reveals that the proposed method can meet the precision demand of space narrow butt joint.
Niemi, Antti H.
2013-12-01
We investigate the application of the discontinuous Petrov-Galerkin (DPG) finite element framework to stationary convection-diffusion problems. In particular, we demonstrate how the quasi-optimal test space norm improves the robustness of the DPG method with respect to vanishing diffusion. We numerically compare coarse-mesh accuracy of the approximation when using the quasi-optimal norm, the standard norm, and the weighted norm. Our results show that the quasi-optimal norm leads to more accurate results on three benchmark problems in two spatial dimensions. We address the problems associated to the resolution of the optimal test functions with respect to the quasi-optimal norm by studying their convergence numerically. In order to facilitate understanding of the method, we also include a detailed explanation of the methodology from the algorithmic point of view. © 2013 Elsevier Ltd. All rights reserved.
Strauss, R. Du Toit; Effenberger, Frederic
2017-10-01
In this review, an overview of the recent history of stochastic differential equations (SDEs) in application to particle transport problems in space physics and astrophysics is given. The aim is to present a helpful working guide to the literature and at the same time introduce key principles of the SDE approach via "toy models". Using these examples, we hope to provide an easy way for newcomers to the field to use such methods in their own research. Aspects covered are the solar modulation of cosmic rays, diffusive shock acceleration, galactic cosmic ray propagation and solar energetic particle transport. We believe that the SDE method, due to its simplicity and computational efficiency on modern computer architectures, will be of significant relevance in energetic particle studies in the years to come.
Tian, Jialin; Madaras, Eric I.
2009-01-01
The development of a robust and efficient leak detection and localization system within a space station environment presents a unique challenge. A plausible approach includes the implementation of an acoustic sensor network system that can successfully detect the presence of a leak and determine the location of the leak source. Traditional acoustic detection and localization schemes rely on the phase and amplitude information collected by the sensor array system. Furthermore, the acoustic source signals are assumed to be airborne and far-field. Likewise, there are similar applications in sonar. In solids, there are specialized methods for locating events that are used in geology and in acoustic emission testing that involve sensor arrays and depend on a discernable phase front to the received signal. These methods are ineffective if applied to a sensor detection system within the space station environment. In the case of acoustic signal location, there are significant baffling and structural impediments to the sound path and the source could be in the near-field of a sensor in this particular setting.
Wang, Jiang; Yang, Chen; Wang, Ruofan; Yu, Haitao; Cao, Yibin; Liu, Jing
2016-10-01
In this paper, EEG series are applied to construct functional connections with the correlation between different regions in order to investigate the nonlinear characteristic and the cognitive function of the brain with Alzheimer's disease (AD). First, limited penetrable visibility graph (LPVG) and phase space method map single EEG series into networks, and investigate the underlying chaotic system dynamics of AD brain. Topological properties of the networks are extracted, such as average path length and clustering coefficient. It is found that the network topology of AD in several local brain regions are different from that of the control group with no statistically significant difference existing all over the brain. Furthermore, in order to detect the abnormality of AD brain as a whole, functional connections among different brain regions are reconstructed based on similarity of clustering coefficient sequence (CCSS) of EEG series in the four frequency bands (delta, theta, alpha, and beta), which exhibit obvious small-world properties. Graph analysis demonstrates that for both methodologies, the functional connections between regions of AD brain decrease, particularly in the alpha frequency band. AD causes the graph index complexity of the functional network decreased, the small-world properties weakened, and the vulnerability increased. The obtained results show that the brain functional network constructed by LPVG and phase space method might be more effective to distinguish AD from the normal control than the analysis of single series, which is helpful for revealing the underlying pathological mechanism of the disease.
Directory of Open Access Journals (Sweden)
Morteza Eskandari-Ghadi
2014-06-01
Full Text Available This paper is concerned with investigation of vertical impedance function of a surface rigid circular foundation resting on a semi-infinite transversely isotropic alluvium. To this end, the equations of motion in cylindrical coordinate system, which because of axissymmetry are two coupled equations, are converted into one partial differential equation using a method of potential function. The governing partial differential equation for the potential function is solved via implementing Hankel integral transforms in radial direction. The vertical and radial components of displacement vector are determined with the use of transformed displacement-potential function relationships. The mixed boundary conditions at the surface are satisfied by specifying the traction between the rigid foundation and the underneath alluvium in a special function space introduced in this paper, where the vertical displacements are forced to satisfy the rigid boundary condition. Through exercising these restraints, the normal traction and then the vertical impedance function are obtained. The results are then compared with the existing results in the literature for the simpler case of isotropic half-space, which shows an excellent agreement. Eventually, the impedance functions are presented in terms of dimensionless frequency for different materials. The method presented here may be used to obtain the impedance function in any other direction as well as in buried footing in layered media.
Xu, Rui; Zhou, Xiangrong; Hirano, Yasushi; Tachibana, Rie; Hara, Takeshi; Kido, Shoji; Fujita, Hiroshi
2013-01-01
Minimum description length (MDL) based group-wise registration was a state-of-the-art method to determine the corresponding points of 3D shapes for the construction of statistical shape models (SSMs). However, it suffered from the problem that determined corresponding points did not uniformly spread on original shapes, since corresponding points were obtained by uniformly sampling the aligned shape on the parameterized space of unit sphere. We proposed a particle-system based method to obtain adaptive sampling positions on the unit sphere to resolve this problem. Here, a set of particles was placed on the unit sphere to construct a particle system whose energy was related to the distortions of parameterized meshes. By minimizing this energy, each particle was moved on the unit sphere. When the system became steady, particles were treated as vertices to build a spherical mesh, which was then relaxed to slightly adjust vertices to obtain optimal sampling-positions. We used 47 cases of (left and right) lungs and 50 cases of livers, (left and right) kidneys, and spleens for evaluations. Experiments showed that the proposed method was able to resolve the problem of the original MDL method, and the proposed method performed better in the generalization and specificity tests.
Directory of Open Access Journals (Sweden)
Rui Xu
2013-01-01
Full Text Available Minimum description length (MDL based group-wise registration was a state-of-the-art method to determine the corresponding points of 3D shapes for the construction of statistical shape models (SSMs. However, it suffered from the problem that determined corresponding points did not uniformly spread on original shapes, since corresponding points were obtained by uniformly sampling the aligned shape on the parameterized space of unit sphere. We proposed a particle-system based method to obtain adaptive sampling positions on the unit sphere to resolve this problem. Here, a set of particles was placed on the unit sphere to construct a particle system whose energy was related to the distortions of parameterized meshes. By minimizing this energy, each particle was moved on the unit sphere. When the system became steady, particles were treated as vertices to build a spherical mesh, which was then relaxed to slightly adjust vertices to obtain optimal sampling-positions. We used 47 cases of (left and right lungs and 50 cases of livers, (left and right kidneys, and spleens for evaluations. Experiments showed that the proposed method was able to resolve the problem of the original MDL method, and the proposed method performed better in the generalization and specificity tests.
Directory of Open Access Journals (Sweden)
Lothar Eysn
2015-05-01
Full Text Available In this study, eight airborne laser scanning (ALS-based single tree detection methods are benchmarked and investigated. The methods were applied to a unique dataset originating from different regions of the Alpine Space covering different study areas, forest types, and structures. This is the first benchmark ever performed for different forests within the Alps. The evaluation of the detection results was carried out in a reproducible way by automatically matching them to precise in situ forest inventory data using a restricted nearest neighbor detection approach. Quantitative statistical parameters such as percentages of correctly matched trees and omission and commission errors are presented. The proposed automated matching procedure presented herein shows an overall accuracy of 97%. Method based analysis, investigations per forest type, and an overall benchmark performance are presented. The best matching rate was obtained for single-layered coniferous forests. Dominated trees were challenging for all methods. The overall performance shows a matching rate of 47%, which is comparable to results of other benchmarks performed in the past. The study provides new insight regarding the potential and limits of tree detection with ALS and underlines some key aspects regarding the choice of method when performing single tree detection for the various forest types encountered in alpine regions.
International Nuclear Information System (INIS)
Han, Jaeyoung; Jung, Mooncheong; Yu, Sangseok; Yi, Sun
2016-01-01
In this study, a model reference adaptive controller is developed to regulate the outlet air flow rate of centrifugal compressor for automotive supercharger. The centrifugal compressor is developed using the analytical based method to predict the transient behavior of operating and the designed model is validated with experimental data to confirm the system accuracy. The model reference adaptive control structure consists of a compressor model and a MRAC(model reference adaptive control) mechanism. The feedback control do not robust with variation of system parameter but the applied adaptive control is robust even if the system parameter is changed. As a result, the MRAC was regulated to reference air flow rate. Also MRAC was found to be more robust control compared with the feedback control even if the system parameter is changed.
Hao, Xiao-Hu; Zhang, Gui-Jun; Zhou, Xiao-Gen; Yu, Xu-Feng
2016-01-01
To address the searching problem of protein conformational space in ab-initio protein structure prediction, a novel method using abstract convex underestimation (ACUE) based on the framework of evolutionary algorithm was proposed. Computing such conformations, essential to associate structural and functional information with gene sequences, is challenging due to the high-dimensionality and rugged energy surface of the protein conformational space. As a consequence, the dimension of protein conformational space should be reduced to a proper level. In this paper, the high-dimensionality original conformational space was converted into feature space whose dimension is considerably reduced by feature extraction technique. And, the underestimate space could be constructed according to abstract convex theory. Thus, the entropy effect caused by searching in the high-dimensionality conformational space could be avoided through such conversion. The tight lower bound estimate information was obtained to guide the searching direction, and the invalid searching area in which the global optimal solution is not located could be eliminated in advance. Moreover, instead of expensively calculating the energy of conformations in the original conformational space, the estimate value is employed to judge if the conformation is worth exploring to reduce the evaluation time, thereby making computational cost lower and the searching process more efficient. Additionally, fragment assembly and the Monte Carlo method are combined to generate a series of metastable conformations by sampling in the conformational space. The proposed method provides a novel technique to solve the searching problem of protein conformational space. Twenty small-to-medium structurally diverse proteins were tested, and the proposed ACUE method was compared with It Fix, HEA, Rosetta and the developed method LEDE without underestimate information. Test results show that the ACUE method can more rapidly and more
Prioritizing the mHealth Design Space: A Mixed-Methods Analysis of Smokers’ Perspectives
BlueSpruce, June; Catz, Sheryl L; McClure, Jennifer B
2016-01-01
Background Smoking remains the leading cause of preventable disease and death in the United States. Therefore, researchers are constantly exploring new ways to promote smoking cessation. Mobile health (mHealth) technologies could be effective cessation tools. Despite the availability of commercial quit-smoking apps, little research to date has examined smokers’ preferred treatment intervention components (ie, design features). Honoring these preferences is important for designing programs that are appealing to smokers and may be more likely to be adopted and used. Objective The aim of this study was to understand smokers’ preferred design features of mHealth quit-smoking tools. Methods We used a mixed-methods approach consisting of focus groups and written surveys to understand the design preferences of adult smokers who were interested in quitting smoking (N=40). Focus groups were stratified by age to allow differing perspectives to emerge between older (>40 years) and younger (brainstorming exercise followed by participant reactions to contrasting design options for communicating with smokers, providing social support, and incentivizing program use. Participants rated the importance of preselected design features on an exit survey. Qualitative analyses examined emergent discussion themes and quantitative analyses compared feature ratings to determine which were perceived as most important. Results Participants preferred a highly personalized and adaptive mHealth experience. Their ideal mHealth quit-smoking tool would allow personalized tracking of their progress, adaptively tailored feedback, and real-time peer support to help manage smoking cravings. Based on qualitative analysis of focus group discussion, participants preferred pull messages (ie, delivered upon request) over push messages (ie, sent automatically) and preferred interaction with other smokers through closed social networks. Preferences for entertaining games or other rewarding incentives to
Asteroseismology: Data Analysis Methods and Interpretation for Space and Ground-based Facilities
Campante, T. L.
2012-06-01
This dissertation has been submitted to the Faculdade de Ciências da Universidade do Porto in partial fulfillment of the requirements for the PhD degree in Astronomy. The scientific results presented herein follow from the research activity performed under the supervision of Dr. Mário João Monteiro at the Centro de Astrofísica da Universidade do Porto and Dr. Hans Kjeldsen at the Institut for Fysik og Astronomi, Aarhus Universitet. The dissertation is composed of three chapters and a list of appendices. Chapter 1 serves as an unpretentious and rather general introduction to the field of asteroseismology of solar-like stars. It starts with a historical account of the field of asteroseismology followed by a general review of the basic physics and properties of stellar pulsations. Emphasis is then naturally placed on the stochastic excitation of stellar oscillations and on the potential of asteroseismic inference. The chapter closes with a discussion about observational techniques and the observational status of the field. Chapter 2 is devoted to the subject of data analysis in asteroseismology. This is an extensive subject, therefore, a compilation is presented of the relevant data analysis methods and techniques employed contemporarily in asteroseismology of solar-like stars. Special attention has been drawn to the subject of statistical inference both from the competing Bayesian and frequentist perspectives. The chapter ends with a description of the implementation of a pipeline for mode parameter analysis of Kepler data. In the course of these two first chapters, reference is made to a series of articles led by the author (or otherwise having greatly benefited from his contribution) that can be found in Appendices A to E. Chapter 3 then goes on to present a series of additional published results.
Yu, Sheng-Tao
2001-01-01
This document reports the conclusion and findings of our research activities for this grant. The goal of the project is the development and application of the method of Space-Time Conservation Element and Solution Element, or the CE/SE method, to simulate chemically reacting flows. The product of this project will be a high-fidelity, time-accurate flow solver analyzing unsteady flow fields advanced propulsion concepts, including the low-emission turbojet engine combustion and flow fields of the Pulse Detonation Engines (PDE). Based on the documents and computer software of the CE/SE method that we have received from the CE/SE working group at NASA Lewis, we have focused our research effort on addressing outstanding technical issues related to the extension of the CE/SE method for unsteady, chemically reactive flows. In particular, we have made progresses in the following three aspects: (1) Derivation of the governing equations for reacting flows; (2) Numerical treatments of stiff source terms; and (3) Detailed simulations of ZND detonation waves.
Directory of Open Access Journals (Sweden)
Ion DIMA
2017-06-01
Full Text Available Random vibrations occur during the launch at the fastening interface between thruster brackets and basic support of satellite. These are generated in the launcher by the motion of some mechanical parts, combustion phenomena or structural elements excited by the acoustic environment. The goal of this comparative study is to find a simplified and efficient validation method using FEM PATRAN-NASTRAN software for thruster brackets in the random vibrations environment for space applications. The random vibration analysis requests complex pre/ post processing efforts and large hardware resources for various geometrical shapes. The PATRAN-NASTRAN random vibration analysis consists of frequency response analysis (111 solver and Acceleration Spectral Density (ASD diagram, taking into account the natural frequencies of the bracket. The Miles method computes the root mean square acceleration (aRMS using the natural frequencies and the ASD diagram as input. As a conservative hypothesis in the random analysis, the three sigma standard deviation criteria in normal Gaussian distribution is applied at these RMS acceleration values, which means to multiply the aRMS by a load factor of three. Simplified method consists of using linear static PATRAN-NASTRAN analysis (101 solver where the aRMS are introduced as loads. For validation of the simplified method, a comparative study was made between the random vibration and the linear static analysis. The final results are presented in detail in this article.
Method and Circuit for In-Situ Health Monitoring of Solar Cells in Space
Krasowski, Michael J.; Prokop, Norman F.
2010-01-01
This innovation represents a method and circuit realization of a system designed to make in-situ measurements of test solar-cell operational parameters on orbit using readily available high-temperature and high-ionizing-radiation- tolerant electronic components. This innovation enables on-orbit in-situ solar-array health monitoring and is in response to a need recognized by the U.S. Air Force for future solar arrays for unmanned spacecraft. This system can also be constructed out of commercial-grade electronics and can be embedded into terrestrial solar power system as a diagnostics instrument. This innovation represents a novel approach to I-V curve measurement that is radiation and temperature hard, consumes very few system resources, is economical, and utilizes commercially available components. The circuit will also operate at temperatures as low as 55 C and up to +225 C, allowing it to reside close to the array in direct sunlight. It uses a swept mode transistor functioning as a resistive load while utilizing the solar cells themselves as the biasing device, so the size of the instrument is small and there is no danger of over-driving the cells. Further, this innovation utilizes nearly universal spacecraft bus resources and therefore can be readily adapted to any spacecraft bus allowing for ease of retrofit, or designed into new systems without requiring the addition of infrastructure. One unique characteristic of this innovation is that it effects the measurement of I-V curves without the use of large resistor arrays or active current sources normally used to characterize cells. A single transistor is used as a variable resistive load across the cell. This multi-measurement instrument was constructed using operational amplifiers, analog switches, voltage regulators, MOSFETs, resistors, and capacitors. The operational amplifiers, analog switches, and voltage regulators are silicon-on-insulator (SOI) technology known for its hardness to the effects of ionizing
Prioritizing the mHealth Design Space: A Mixed-Methods Analysis of Smokers' Perspectives.
Hartzler, Andrea Lisabeth; BlueSpruce, June; Catz, Sheryl L; McClure, Jennifer B
2016-08-05
Smoking remains the leading cause of preventable disease and death in the United States. Therefore, researchers are constantly exploring new ways to promote smoking cessation. Mobile health (mHealth) technologies could be effective cessation tools. Despite the availability of commercial quit-smoking apps, little research to date has examined smokers' preferred treatment intervention components (ie, design features). Honoring these preferences is important for designing programs that are appealing to smokers and may be more likely to be adopted and used. The aim of this study was to understand smokers' preferred design features of mHealth quit-smoking tools. We used a mixed-methods approach consisting of focus groups and written surveys to understand the design preferences of adult smokers who were interested in quitting smoking (N=40). Focus groups were stratified by age to allow differing perspectives to emerge between older (>40 years) and younger (quantitative analyses compared feature ratings to determine which were perceived as most important. Participants preferred a highly personalized and adaptive mHealth experience. Their ideal mHealth quit-smoking tool would allow personalized tracking of their progress, adaptively tailored feedback, and real-time peer support to help manage smoking cravings. Based on qualitative analysis of focus group discussion, participants preferred pull messages (ie, delivered upon request) over push messages (ie, sent automatically) and preferred interaction with other smokers through closed social networks. Preferences for entertaining games or other rewarding incentives to encourage program use differed by age group. Based on quantitative analysis of surveys, participants rated the importance of select design features significantly differently (Ptechnology, and frequency of smoking. Future mHealth cessation aids should be designed with an understanding of smokers' needs and preferences for these tools. Doing so does not guarantee
Directory of Open Access Journals (Sweden)
Patel S.M.
2013-01-01
Full Text Available A free-space transmission method has been used for reliable shielding effectiveness measurement of the easily available textile materials. Textiles with three different yarn densities were studied for their shielding effectiveness with the help of a vector network analyzer and laboratory calibrated two X-band horn antennas. The expressions of uncertainty estimation have been derived in accordance with the present free-space measurement setup for the calculated SE values. The measurements have shown that an electromagnetic energy can be maximum shielded up to 16.24 dB with measurement uncertainty less than 0.21 dB in 8.2 to 12.4 GHz range by a 160.85 μm textile. Thus, a thin textile with a high density can have higher shielding and this property mainly depends on its intrinsic structure, frequency range and thickness. This study promises the potential applications of such materials as a very cost effective shielding material at microwave frequencies with some modifications.
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Chen Wei
2015-01-01
Full Text Available In recent years, the ancient town of update and development has become a new hot spot, the study of old town renewal of concern is gradually warming. And again there are a lot of space in the middle of the old town renewal design and traditional style, space activities and use the contradiction between population, which becomes a problem urgently to be solved in design stage. The purpose of this study was to explore old town design space and behavior, traditional and modern conflict resolution methods, and to present the town development and design with a design concept. This paper’ uses three theories of urban design (The relationship between figure and ground, Contact theory and Place theory as a real-time monitoring, assessment, comparison of methods, to study Yan Dao Ancient Town, and the space for analysis. In the research, this paper based on the design theory of the three major city as a starting point, detailedly describes the different types in a certain area of difference in the behavior and the properties of space, and the ancient town of Hubei Shennongjia forest region salt path planning and design practice, the ancient town of updating the connotation of the historical context and space behavior of connection. The conclusion of this thesis put forward the method of that based on the space shape of ancient design method of its application in practice.
DEFF Research Database (Denmark)
Bolashikov, Zhecho Dimitrov
and by protecting medical staff, patients and visitors from cross-infection in hospital wards. The first part of the thesis focuses on improvement of inhaled air quality and thus reduction in the risk from cross-infection by advanced ventilation, providing clean air close to the occupants with personalized...... environment related to control and, handling the spread and treating patients with contagious airborne diseases, as well as problems with insufficient space in hospital wards in times of epidemics and pandemics.......The current Ph.D. thesis deals with new advanced methods of air distribution in occupied places aimed to improve the inhaled air quality and to reduce the risk from airborne cross infection among the occupants. The existing ventilation strategies nowadays are not able to provide enough clean air...
Blumenstock, Kenneth A.
2017-01-01
Throughout the history of the Hubble Space Telescope (HST) program, gyro current increases have been observed to occur, often times leading to gyro failure. The explanation was that debris from the surfaces of the gas bearings, with only 1.27 micron clearance, resulted in rotor restriction, which increased friction, torque, and current. However, the rotor restriction theory never could account for the fact that a restart of the gyro would restore the current back to nominal. An effort was made to understand this puzzling gyro behavior after two HST gyros exhibited increased current within the same week in November 2015. A review board was created to resolve these anomalies and generate operational procedures to potentially extend gyro life. A new understanding of gyro current behavior led to implementation of a method that could potentially save a failing gyro.
Gaudiuso, Rosalba; Dell'Aglio, Marcella; De Pascale, Olga; Senesi, Giorgio S; De Giacomo, Alessandro
2010-01-01
Analytical applications of Laser Induced Breakdown Spectroscopy (LIBS), namely optical emission spectroscopy of laser-induced plasmas, have been constantly growing thanks to its intrinsic conceptual simplicity and versatility. Qualitative and quantitative analysis can be performed by LIBS both by drawing calibration lines and by using calibration-free methods and some of its features, so as fast multi-elemental response, micro-destructiveness, instrumentation portability, have rendered it particularly suitable for analytical applications in the field of environmental science, space exploration and cultural heritage. This review reports and discusses LIBS achievements in these areas and results obtained for soils and aqueous samples, meteorites and terrestrial samples simulating extraterrestrial planets, and cultural heritage samples, including buildings and objects of various kinds.
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Tieliang Yang
2016-01-01
Full Text Available This paper presents an analytical study for sound radiation of functionally graded materials (FGM plate based on the three-dimensional theory of elasticity. The FGM plate is a mixture of metal and ceramic, and its material properties are assumed to have smooth and continuous variation in the thickness direction according to a power-law distribution in terms of volume fractions of the constituents. Based on the three-dimensional theory of elasticity and state space method, the governing equations with variable coefficients of the FGM plate are derived. The sound radiation of the vibration plate is calculated with Rayleigh integral. Comparisons of the present results with those of solutions in the available literature are made and good agreements are achieved. Finally, some parametric studies are carried out to investigate the sound radiation properties of FGM plates.
International Nuclear Information System (INIS)
Beckman, S.P.; Chelikowsky, James R.
2007-01-01
The structure and properties of vacancies in a 2 nm Si nano-crystal are studied using a real space density functional theory/pseudopotential method. It is observed that a vacancy's electronic properties and energy of formation are directly related to the local symmetry of the vacancy site. The formation energy for vacancies and Frenkel pair are calculated. It is found that both defects have lower energy in smaller crystals. In a 2 nm nano-crystal the energy to form a Frenkel pair is 1.7 eV and the energy to form a vacancy is no larger than 2.3 eV. The energy barrier for vacancy diffusion is examined via a nudged elastic band algorithm
Balsara, Dinshaw S.
2017-12-01
As computational astrophysics comes under pressure to become a precision science, there is an increasing need to move to high accuracy schemes for computational astrophysics. The algorithmic needs of computational astrophysics are indeed very special. The methods need to be robust and preserve the positivity of density and pressure. Relativistic flows should remain sub-luminal. These requirements place additional pressures on a computational astrophysics code, which are usually not felt by a traditional fluid dynamics code. Hence the need for a specialized review. The focus here is on weighted essentially non-oscillatory (WENO) schemes, discontinuous Galerkin (DG) schemes and PNPM schemes. WENO schemes are higher order extensions of traditional second order finite volume schemes. At third order, they are most similar to piecewise parabolic method schemes, which are also included. DG schemes evolve all the moments of the solution, with the result that they are more accurate than WENO schemes. PNPM schemes occupy a compromise position between WENO and DG schemes. They evolve an Nth order spatial polynomial, while reconstructing higher order terms up to Mth order. As a result, the timestep can be larger. Time-dependent astrophysical codes need to be accurate in space and time with the result that the spatial and temporal accuracies must be matched. This is realized with the help of strong stability preserving Runge-Kutta schemes and ADER (Arbitrary DERivative in space and time) schemes, both of which are also described. The emphasis of this review is on computer-implementable ideas, not necessarily on the underlying theory.
Directory of Open Access Journals (Sweden)
Nowak Aleksander
2015-12-01
Full Text Available Nowadays, we can observe an increase in research on the use of small unmanned autonomous vessel (SUAV to patrol and guiding critical areas including harbours. The proposal to “snapshot” RAIM (Receiver Autonomous Integrity Monitoring method for GNSS receivers mounted on SUAV operating in poor space segment geometry is presented in the paper. Existing “snapshot” RAIM methods and algorithms which are used in practical applications have been developed for airborne receivers, thus two main assumptions have been made. The first one is that the geometry of visible satellites is strong. It means that the exclusion of any satellite from the positioning solution don’t cause significant deterioration of Dilution of Precision (DOP coefficients. The second one is that only one outlier could appear in pseudorange measurements. In case of SUAV operating in harbour these two assumptions cannot be accepted. Because of their small dimensions, GNSS antenna is only a few decimetres above sea level and regular ships, buildings and harbour facilities block and reflect satellite signals. Thus, different approach to “snapshot” RAIM is necessary. The proposal to method based on analyses of allowable maximal separation of positioning sub-solutions with using some information from EGNOS messages is described in the paper. Theoretical assumptions and results of numerical experiments are presented.
Rigatos, Gerasimos G
2017-01-01
The book conclusively solves problems associated with the control and estimation of nonlinear and chaotic dynamics in ﬁnancial systems when these are described in the form of nonlinear ordinary diﬀerential equations. It then addresses problems associated with the control and estimation of ﬁnancial systems governed by partial diﬀerential equations (e.g. the Black–Scholes partial differential equation (PDE) and its variants). Lastly it an offers optimal solution to the problem of statistical validation of computational models and tools used to support ﬁnancial engineers in decision making. The application of state-space models in ﬁnancial engineering means that the heuristics and empirical methods currently in use in decision-making procedures for ﬁnance can be eliminated. It also allows methods of fault-free performance and optimality in the management of assets and capitals and methods assuring stability in the functioning of ﬁnancial systems to be established. Covering the following key are...
Dynamic simulation of a pilot scale vacuum gas oil hydrocracking unit by the space-time CE/SE method
Energy Technology Data Exchange (ETDEWEB)
Sadighi, S.; Ahmad, A. [Institute of Hydrogen Economy, Universiti Teknologi Malaysia, Johor Bahru (Malaysia); Shirvani, M. [Faculty of Chemical Engineering, University of Science and Technology, Tehran (Iran, Islamic Republic of)
2012-05-15
This work introduces a modified space-time conservation element/solution element (CE/SE) method for the simulation of the dynamic behavior of a pilot-scale hydrocracking reactor. With this approach, a four-lump dynamic model including vacuum gas oil (VGO), middle distillate, naphtha and gas is solved. The proposed method is capable of handling the stiffness of the partial differential equations resulting from the hydrocracking reactions. To have a better judgment, the model is also solved by the finite difference method (FDM), and the results from both approaches are compared. Initially, the absolute average deviation of the cold dynamic simulation using the CE/SE approach is 8.98 %, which is better than that obtained using the FDM. Then, the stability analysis proves that for achieving an appropriate response from the dynamic model, the Courant number, which is a function of the time step size, mesh size and volume flow rate through the catalytic bed, should be less than 1. Finally, it is found that, following a careful selection of these parameters, the CE/SE solutions to the hydrocracking model can produce higher accuracy than the FDM results. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Wang, Xiao-Yen; Himansu, Ananda; Chang, Sin-Chung; Jorgenson, Philip C. E.
2000-01-01
The Internal Propagation problems, Fan Noise problem, and Turbomachinery Noise problems are solved using the space-time conservation element and solution element (CE/SE) method. The problems in internal propagation problems address the propagation of sound waves through a nozzle. Both the nonlinear and linear quasi 1D Euler equations are solved. Numerical solutions are presented and compared with the analytical solution. The fan noise problem concerns the effect of the sweep angle on the acoustic field generated by the interaction of a convected gust with a cascade of 3D flat plates. A parallel version of the 3D CE/SE Euler solver is developed and employed to obtain numerical solutions for a family of swept flat plates. Numerical solutions for sweep angles of 0, 5, 10, and 15 deg are presented. The turbomachinery problems describe the interaction of a 2D vortical gust with a cascade of flat-plate airfoils with/without a downstream moving grid. The 2D nonlinear Euler Equations are solved and the converged numerical solutions are presented and compared with the corresponding analytical solution. All the comparisons demonstrate that the CE/SE method is capable of solving aeroacoustic problems with/without shock waves in a simple and efficient manner. Furthermore, the simple non-reflecting boundary condition used in the CE/SE method which is not based on the characteristic theory works very well in 1D, 2D and 3D problems.
Directory of Open Access Journals (Sweden)
Nur Azemil
2017-09-01
Full Text Available Development of manufacturing and service institutions can not be separated from the role of human resources. Human resources have an important role in fulfilling vision and mission. University of A is one of the private educational institutions in East Java to achieve the goal must be managed properly that can be utilized optimally, this can be done by analyzing workload and performance or optimizing the number of employees. The purpose this research is measure workload and effect the employee’s performance. Measurement of workload is using National Aeronautics and Space Administration-Task Load Index (NASA-TLX method, NASA-TLX method is rating multidimentional subjective mental workload that divides the workload based on the average load of 6 dimensions, and the measurement of performance is using questionnaire with 5 scales by likert scale. The results showed that employees who have Medium workload is 8%, High workload is 84% and Very high workload is 8%. The result of the questionnaire showed the category of employee’s performance, simply performance is 24% and satisfactory performance is 76%. From the statistical test by using Chi Square method, it is known that the value = 5,9915 and = 2,2225, the result shows < , then is accepted and is rejected. Thus, there is influence between the workload of employees and the employees’s performance.
DEFF Research Database (Denmark)
2005-01-01
of digital technology with space poses new challenges that call for new approaches. Creative alternatives to traditional systems methodologies are called for when designers use digital media to create new possibilities for action in space. Design Spaces explores how design and media art can provide creative......Digital technologies and media are becoming increasingly embodied and entangled in the spaces and places at work and at home. However, our material environment is more than a geometric abstractions of space: it contains familiar places, social arenas for human action. For designers, the integration...... alternatives for integrating digital technology with space. Connecting practical design work with conceptual development and theorizing, art with technology, and usesr-centered methods with social sciences, Design Spaces provides a useful research paradigm for designing ubiquitous computing. This book...
DEFF Research Database (Denmark)
2005-01-01
Digital technologies and media are becoming increasingly embodied and entangled in the spaces and places at work and at home. However, our material environment is more than a geometric abstractions of space: it contains familiar places, social arenas for human action. For designers, the integration...... of digital technology with space poses new challenges that call for new approaches. Creative alternatives to traditional systems methodologies are called for when designers use digital media to create new possibilities for action in space. Design Spaces explores how design and media art can provide creative...... alternatives for integrating digital technology with space. Connecting practical design work with conceptual development and theorizing, art with technology, and usesr-centered methods with social sciences, Design Spaces provides a useful research paradigm for designing ubiquitous computing. This book...
Branduardi, Davide; Faraldo-Gómez, José D.
2014-01-01
The string method is a molecular-simulation technique that aims to calculate the minimum free-energy path of a chemical reaction or conformational transition, in the space of a pre-defined set of reaction coordinates that is typically highly dimensional. Any descriptor may be used as a reaction coordinate, but arguably the Cartesian coordinates of the atoms involved are the most unprejudiced and intuitive choice. Cartesian coordinates, however, present a non-trivial problem, in that they are not invariant to rigid-body molecular rotations and translations, which ideally ought to be unrestricted in the simulations. To overcome this difficulty, we reformulate the framework of the string method to integrate an on-the-fly structural-alignment algorithm. This approach, referred to as SOMA (String method with Optimal Molecular Alignment), enables the use of Cartesian reaction coordinates in freely tumbling molecular systems. In addition, this scheme permits the dissection of the free-energy change along the most probable path into individual atomic contributions, thus revealing the dominant mechanism of the simulated process. This detailed analysis also provides a physically-meaningful criterion to coarse-grain the representation of the path. To demonstrate the accuracy of the method we analyze the isomerization of the alanine dipeptide in vacuum and the chair-to-inverted-chair transition of β-D mannose in explicit water. Notwithstanding the simplicity of these systems, the SOMA approach reveals novel insights into the atomic mechanism of these isomerizations. In both cases, we find that the dynamics and the energetics of these processes are controlled by interactions involving only a handful of atoms in each molecule. Consistent with this result, we show that a coarse-grained SOMA calculation defined in terms of these subsets of atoms yields nearidentical minimum free-energy paths and committor distributions to those obtained via a highly-dimensional string. PMID
Nizam, Navid Ibtehaj; Alam, S Kaisar; Hasan, Md Kamrul
2017-10-01
We present a novel method for estimating the mean scatterer spacing (MSS) of breast tumors using ensemble empirical mode decomposition (EEMD) domain analysis of deconvolved backscattered radio frequency (RF) data. The autoregressive (AR) spectrum from which the MSS is estimated is obtained from the intrinsic mode functions (IMFs) due to regular scatterers embedded in RF data corrupted by the diffuse scatterers. The IMFs are chosen by giving priority to the presence of an enhanced fundamental harmonic and the presence of a greater number of higher harmonics in the AR spectrum estimated from the IMFs. The AR model order is chosen by minimizing the mean absolute percentage error (MAPE) criterion. In order to ensure that the backscattered data is indeed from a source of coherent scattering, we begin by performing a non-parametric Kolmogorov-Smirnov (K-S) classification test on the backscattered RF data. Deconvolution of the backscattered RF data, which have been classified by the K-S test as sources of significant coherent scattering, is done to reduce the system effect. EEMD domain analysis is then performed on the deconvolved data. The proposed method is able to recover the harmonics associated with the regular scatterers and overcomes many problems encountered while estimating the MSS from the AR spectrum of raw RF data. Using our technique, a mean absolute percentage error (MAPE) of 5.78% is obtained while estimating the MSS from simulated data, which is lower than that of the existing techniques. Our proposed method is shown to outperform the state of the art techniques, namely, singular spectrum analysis, generalized spectrum (GS), spectral autocorrelation (SAC), and modified SAC for different simulation conditions. The MSS for in vivo normal breast tissue is found to be 0.69 ± 0.04 mm; for benign and malignant tumors it is found to be 0.73 ± 0.03 and 0.79 ± 0.04 mm, respectively. The separation between the MSS values of normal and benign tissues for our
Kim, Jaewook; Hong, Kwangwoo; Choi, Sunghwan; Hwang, Sang-Yeon; Youn Kim, Woo
2015-12-21
We developed a program code of configuration interaction singles (CIS) based on a numerical grid method. We used Kohn-Sham (KS) as well as Hartree-Fock (HF) orbitals as a reference configuration and Lagrange-sinc functions as a basis set. Our calculations show that KS-CIS is more cost-effective and more accurate than HF-CIS. The former is due to the fact that the non-local HF exchange potential greatly reduces the sparsity of the Hamiltonian matrix in grid-based methods. The latter is because the energy gaps between KS occupied and virtual orbitals are already closer to vertical excitation energies and thus KS-CIS needs small corrections, whereas HF results in much larger energy gaps and more diffuse virtual orbitals. KS-CIS using the Lagrange-sinc basis set also shows a better or a similar accuracy to smaller orbital space compared to the standard HF-CIS using Gaussian basis sets. In particular, KS orbitals from an exact exchange potential by the Krieger-Li-Iafrate approximation lead to more accurate excitation energies than those from conventional (semi-) local exchange-correlation potentials.
Chang, Sin-Chung; Wang, Xiao-Yen; To, Wai-Ming
2000-01-01
In the space-time conservation element and solution element (CE/SE) method, the independent marching variables used comprise not only the mesh value of the physical dependent variables but also, in contrast to it typical numerical method, the Mesh values of the spatial derivatives of the physical variables The use of the extra marching variables results from the need to construct the two-level explicit and nondissipative schemes which are at the core of the CE/SE development. It also results from the need to minimize the stencil while maintaining accuracy. In this paper using the 1D(sub (alpha)-mu) scheme as an example, the effect of this added complication on consistency, accuracy and operation count is assessed. As part of this effort, an equivalent yet more efficient form of the alpha-mu scheme in which the independent marching variables are the local fluxes tied to each mesh point is introduced. Also, the intriguing relations that exist among the alpha-mu. Leapfrog, and DuFort-Frankel schemes are further explored. In addition, the redundance of the Leapfrog, DUFort-Frankel, and Lax scheme and the remedy for this redundance are discussed. This paper is concluded with the construction and evaluation of a CE/SE solver for the inviscid Burger equation.
Energy Technology Data Exchange (ETDEWEB)
Pin, F.G.; Hacker, C.J.; Gower, K.B.; Morgansen, K.A.
1997-03-01
The efficient utilization of the motion capabilities of mobile manipulators, i.e.. manipulators mounted on mobile platforms, requires the resolution of the kinematically redundant system formed by the addition of the degrees of freedom (d.o.f.) of the platform to those of the manipulator. At the velocity level, the linearized Jacobian equation for such a redundant system represents an underspecified system of algebraic equations, which can be subject to a set of constraints such as obstacles in the workspace and various limits on the joint motions. A method, which we named the FSP (Full Space Parameterization), has recently been developed to resolve such underspecified systems with constraints that may vary in time and in number during a single trajectory. The application of the method to motion planning problems with obstacle and joint limit avoidance was discussed in some of our previous work. In this paper, we present the treatment in the FSP of a non-holonomic constraint on the platform motion, and give corresponding analytical solutions for resolving the redundancy with a general optimization criterion. Comparative trajectories involving a 10 d.o.f. mobile manipulator testbed moving with and without a non-holonomic constraint for the platform motion, are presented to illustrate the use and efficiency of the FSP approach in motion planning problems for highly kinematically redundant and constrained systems.
Carleo, Giuseppe; Cevolani, Lorenzo; Sanchez-Palencia, Laurent; Holzmann, Markus
2017-07-01
We introduce the time-dependent variational Monte Carlo method for continuous-space Bose gases. Our approach is based on the systematic expansion of the many-body wave function in terms of multibody correlations and is essentially exact up to adaptive truncation. The method is benchmarked by comparison to an exact Bethe ansatz or existing numerical results for the integrable Lieb-Liniger model. We first show that the many-body wave function achieves high precision for ground-state properties, including energy and first-order as well as second-order correlation functions. Then, we study the out-of-equilibrium, unitary dynamics induced by a quantum quench in the interaction strength. Our time-dependent variational Monte Carlo results are benchmarked by comparison to exact Bethe ansatz results available for a small number of particles, and are also compared to quench action results available for noninteracting initial states. Moreover, our approach allows us to study large particle numbers and general quench protocols, previously inaccessible beyond the mean-field level. Our results suggest that it is possible to find correlated initial states for which the long-term dynamics of local density fluctuations is close to the predictions of a simple Boltzmann ensemble.
Inc, Mustafa; Akgül, Ali; Kılıçman, Adem
2013-01-01
The present paper emphasizes Jeffery-Hamel flow: fluid flow between two rigid plane walls, where the angle between them is 2 $\\alpha $ . A new method called the reproducing kernel Hilbert space method (RKHSM) is briefly introduced. The validity of the reproducing kernel method is set by comparing our results with HAM, DTM, and HPM and numerical results for different values of $H$ , $\\alpha $ , and Re. The results show up that the proposed reproducing kernel method can achieve good results in ...
Rash, James
2014-01-01
NASA's space data-communications infrastructure-the Space Network and the Ground Network-provide scheduled (as well as some limited types of unscheduled) data-communications services to user spacecraft. The Space Network operates several orbiting geostationary platforms (the Tracking and Data Relay Satellite System (TDRSS)), each with its own servicedelivery antennas onboard. The Ground Network operates service-delivery antennas at ground stations located around the world. Together, these networks enable data transfer between user spacecraft and their mission control centers on Earth. Scheduling data-communications events for spacecraft that use the NASA communications infrastructure-the relay satellites and the ground stations-can be accomplished today with software having an operational heritage dating from the 1980s or earlier. An implementation of the scheduling methods and algorithms disclosed and formally specified herein will produce globally optimized schedules with not only optimized service delivery by the space data-communications infrastructure but also optimized satisfaction of all user requirements and prescribed constraints, including radio frequency interference (RFI) constraints. Evolutionary algorithms, a class of probabilistic strategies for searching large solution spaces, is the essential technology invoked and exploited in this disclosure. Also disclosed are secondary methods and algorithms for optimizing the execution efficiency of the schedule-generation algorithms themselves. The scheduling methods and algorithms as presented are adaptable to accommodate the complexity of scheduling the civilian and/or military data-communications infrastructure within the expected range of future users and space- or ground-based service-delivery assets. Finally, the problem itself, and the methods and algorithms, are generalized and specified formally. The generalized methods and algorithms are applicable to a very broad class of combinatorial
International Nuclear Information System (INIS)
Kheymits, M D; Leonov, A A; Zverev, V G; Galper, A M; Arkhangelskaya, I V; Arkhangelskiy, A I; Yurkin, Yu T; Bakaldin, A V; Suchkov, S I; Topchiev, N P; Dalkarov, O D
2016-01-01
The GAMMA-400 gamma-ray space-based telescope has as its main goals to measure cosmic γ-ray fluxes and the electron-positron cosmic-ray component produced, theoretically, in dark-matter-particles decay or annihilation processes, to search for discrete γ-ray sources and study them in detail, to examine the energy spectra of diffuse γ-rays — both galactic and extragalactic — and to study gamma-ray bursts (GRBs) and γ-rays from the active Sun. Scientific goals of GAMMA-400 telescope require fine angular resolution. The telescope is of a pair-production type. In the converter-tracker, the incident gamma-ray photon converts into electron-positron pair in the tungsten layer and then the tracks are detected by silicon- strip position-sensitive detectors. Multiple scattering processes become a significant obstacle in the incident-gamma direction reconstruction for energies below several gigaelectronvolts. The method of utilising this process to improve the resolution is proposed in the presented work. (paper)
Directory of Open Access Journals (Sweden)
Jin-Woo Jung
2005-04-01
Full Text Available A new human-friendly assistive home environment, Intelligent Sweet Home (ISH, developed at KAIST, Korea for testing advanced concepts for independent living of the elderly/the physically handicapped. The concept of ISH is to consider the home itself as an intelligent robot. ISH always checks the intention or health status of the resident. Therefore, ISH can do actively the most proper services considering the resident's life-style by the detected intention or emergency information. But, when there are more than two residents, ISH cannot consider the residents' characteristics or tastes if ISH cannot identify who he/she is before. To realize a personalized service system in the intelligent residential space like ISH, we deal with a human-friendly user identification method for ubiquitous computing environment, specially focused on dynamic human footprint recognition. And then, we address some case studies of personalized services that have been experienced by Human-friendly Welfare Robot System research center, KAIST.
Sepehry-Fard, F.; Coulthard, Maurice H.
1995-01-01
The objective of this publication is to introduce the enhancement methods for the overall reliability and maintainability methods of assessment on the International Space Station. It is essential that the process to predict the values of the maintenance time dependent variable parameters such as mean time between failure (MTBF) over time do not in themselves generate uncontrolled deviation in the results of the ILS analysis such as life cycle costs, spares calculation, etc. Furthermore, the very acute problems of micrometeorite, Cosmic rays, flares, atomic oxygen, ionization effects, orbital plumes and all the other factors that differentiate maintainable space operations from non-maintainable space operations and/or ground operations must be accounted for. Therefore, these parameters need be subjected to a special and complex process. Since reliability and maintainability strongly depend on the operating conditions that are encountered during the entire life of the International Space Station, it is important that such conditions are accurately identified at the beginning of the logistics support requirements process. Environmental conditions which exert a strong influence on International Space Station will be discussed in this report. Concurrent (combined) space environments may be more detrimental to the reliability and maintainability of the International Space Station than the effects of a single environment. In characterizing the logistics support requirements process, the developed design/test criteria must consider both the single and/or combined environments in anticipation of providing hardware capability to withstand the hazards of the International Space Station profile. The effects of the combined environments (typical) in a matrix relationship on the International Space Station will be shown. The combinations of the environments where the total effect is more damaging than the cumulative effects of the environments acting singly, may include a
International Nuclear Information System (INIS)
Hoffman, A. J.; Lee, J. C.
2013-01-01
A new time-dependent neutron transport method based on the method of characteristics (MOC) has been developed. Whereas most spatial kinetics methods treat time dependence through temporal discretization, this new method treats time dependence by defining the characteristics to span space and time. In this implementation regions are defined in space-time where the thickness of the region in time fulfills an analogous role to the time step in discretized methods. The time dependence of the local source is approximated using a truncated Taylor series expansion with high order derivatives approximated using backward differences, permitting the solution of the resulting space-time characteristic equation. To avoid a drastic increase in computational expense and memory requirements due to solving many discrete characteristics in the space-time planes, the temporal variation of the boundary source is similarly approximated. This allows the characteristics in the space-time plane to be represented analytically rather than discretely, resulting in an algorithm comparable in implementation and expense to one that arises from conventional time integration techniques. Furthermore, by defining the boundary flux time derivative in terms of the preceding local source time derivative and boundary flux time derivative, the need to store angularly-dependent data is avoided without approximating the angular dependence of the angular flux time derivative. The accuracy of this method is assessed through implementation in the neutron transport code DeCART. The method is employed with variable-order local source representation to model a TWIGL transient. The results demonstrate that this method is accurate and more efficient than the discretized method. (authors)
Wang, Jue; Kwan, Mei-Po; Chai, Yanwei
2018-04-09
Scholars in the fields of health geography, urban planning, and transportation studies have long attempted to understand the relationships among human movement, environmental context, and accessibility. One fundamental question for this research area is how to measure individual activity space, which is an indicator of where and how people have contact with their social and physical environments. Conventionally, standard deviational ellipses, road network buffers, minimum convex polygons, and kernel density surfaces have been used to represent people's activity space, but they all have shortcomings. Inconsistent findings of the effects of environmental exposures on health behaviors/outcomes suggest that the reliability of existing studies may be affected by the uncertain geographic context problem (UGCoP). This paper proposes the context-based crystal-growth activity space as an innovative method for generating individual activity space based on both GPS trajectories and the environmental context. This method not only considers people's actual daily activity patterns based on GPS tracks but also takes into account the environmental context which either constrains or encourages people's daily activity. Using GPS trajectory data collected in Chicago, the results indicate that the proposed new method generates more reasonable activity space when compared to other existing methods. This can help mitigate the UGCoP in environmental health studies.
DEFF Research Database (Denmark)
Brander, David; Rossman, Wayne; Schmitt, Nicholas
2010-01-01
We give an infinite dimensional generalized Weierstrass representation for spacelike constant mean curvature (CMC) surfaces in Minkowski 3-space $\\R^{2,1}$. The formulation is analogous to that given by Dorfmeister, Pedit and Wu for CMC surfaces in Euclidean space, replacing the group $SU_2...... symmetry, as well as studying another class of surfaces for which the metric is rotationally invariant....
Directory of Open Access Journals (Sweden)
Hao Wu
2018-01-01
Full Text Available Urban green space is closely related to the quality of life of residents. However, the traditional approach to its planning often fails to address its actual service capacity and users’ demand. In this study, facilitated by mobile phone location data, more specific features of the spatial distribution of urban residents are identified. Further, population distribution in relation to traffic analysis zones is mapped. On this basis, the two-step floating catchment area method (2SFCA is adopted in combination with urban green space planning to evaluate the per capita area of green space and its accessibility in practice. Subsequently, classification of per capita area and spatial distribution of green spaces within the study area are obtained; thus, urban districts currently with low accessibility to green areas are identified and can be deemed as key areas for the planning of green areas in the future. The study concludes that mobile phone data can be used to more accurately map the spatial distribution of residents; while, the 2SFCA offers a more comprehensive quantitative measuring of the supply and demand of green spaces. The two combined can be used as an important basis for decision-making in the planning of urban green spaces. Since urban green space can be regarded as a kind of public facility, the methodology of the present study is also believed to be applicable in studies of other types of urban facilities.
Schmitz, Oliver; Soenario, Ivan; Vaartjes, Ilonca; Strak, Maciek; Hoek, Gerard; Brunekreef, Bert; Dijst, Martin; Karssenberg, Derek
2016-04-01
Air pollution is one of the major concerns for human health. Associations between air pollution and health are often calculated using long-term (i.e. years to decades) information on personal exposure for each individual in a cohort. Personal exposure is the air pollution aggregated along the space-time path visited by an individual. As air pollution may vary considerably in space and time, for instance due to motorised traffic, the estimation of the spatio-temporal location of a persons' space-time path is important to identify the personal exposure. However, long term exposure is mostly calculated using the air pollution concentration at the x, y location of someone's home which does not consider that individuals are mobile (commuting, recreation, relocation). This assumption is often made as it is a major challenge to estimate space-time paths for all individuals in large cohorts, mostly because limited information on mobility of individuals is available. We address this issue by evaluating multiple approaches for the calculation of space-time paths, thereby estimating the personal exposure along these space-time paths with hyper resolution air pollution maps at national scale. This allows us to evaluate the effect of the space-time path and resulting personal exposure. Air pollution (e.g. NO2, PM10) was mapped for the entire Netherlands at a resolution of 5×5 m2 using the land use regression models developed in the European Study of Cohorts for Air Pollution Effects (ESCAPE, http://escapeproject.eu/) and the open source software PCRaster (http://www.pcraster.eu). The models use predictor variables like population density, land use, and traffic related data sets, and are able to model spatial variation and within-city variability of annual average concentration values. We approximated space-time paths for all individuals in a cohort using various aggregations, including those representing space-time paths as the outline of a persons' home or associated parcel
Arifvianto, B; Leeflang, M A; Zhou, J
2017-04-01
Scaffolds with open, interconnected pores and appropriate mechanical properties are required to provide mechanical support and to guide the formation and development of new tissue in bone tissue engineering. Since the mechanical properties of the scaffold tend to decrease with increasing porosity, a balance must be sought in order to meet these two conflicting requirements. In this research, open, interconnected pores and mechanical properties of biomedical titanium scaffolds prepared by using the space holder method were characterized. Micro-computed tomography (micro-CT) and permeability analysis were carried out to quantify the porous structures and ascertain the presence of open, interconnected pores in the scaffolds fabricated. Diametral compression (DC) tests were performed to generate stress-strain diagrams that could be used to determine the elastic moduli and yield strengths of the scaffolds. Deformation and failure mechanisms involved in the DC tests of the titanium scaffolds were examined. The results of micro-CT and permeability analyses confirmed the presence of open, interconnected pores in the titanium scaffolds with porosity over a range of 31-61%. Among these scaffolds, a maximum specific surface area could be achieved in the scaffold with a total porosity of 5-55%. DC tests showed that the titanium scaffolds with elastic moduli and yield strengths of 0.64-3.47GPa and 28.67-80MPa, respectively, could be achieved. By comprehensive consideration of specific surface area, permeability and mechanical properties, the titanium scaffolds with porosities in a range of 50-55% were recommended to be used in cancellous bone tissue engineering. Copyright © 2017 Elsevier Ltd. All rights reserved.
National Aeronautics and Space Administration — Spaceflight is known to affect immune cell populations. In particular splenic B-cell numbers decrease during spaceflight and in ground-based physiological models....
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Quynh Anh NguyenThi
2011-01-01
Full Text Available We introduce a new implicit iteration method for finding a solution for a variational inequality involving Lipschitz continuous and strongly monotone mapping over the set of common fixed points for a finite family of nonexpansive mappings on Hilbert spaces.
Directory of Open Access Journals (Sweden)
Bisheng He
2014-01-01
Full Text Available A time-space network based optimization method is designed for high-speed rail train timetabling problem to improve the service level of the high-speed rail. The general time-space path cost is presented which considers both the train travel time and the high-speed rail operation requirements: (1 service frequency requirement; (2 stopping plan adjustment; and (3 priority of train types. Train timetabling problem based on time-space path aims to minimize the total general time-space path cost of all trains. An improved branch-and-price algorithm is applied to solve the large scale integer programming problem. When dealing with the algorithm, a rapid branching and node selection for branch-and-price tree and a heuristic train time-space path generation for column generation are adopted to speed up the algorithm computation time. The computational results of a set of experiments on China’s high-speed rail system are presented with the discussions about the model validation, the effectiveness of the general time-space path cost, and the improved branch-and-price algorithm.
Norman, Noraina Hafizan; Worthington, Helen; Chadwick, Stephen Mark
2016-09-01
To compare the clinical performance of nickel titanium (NiTi) versus stainless steel (SS) springs during orthodontic space closure. Two-centre parallel group randomized clinical trial. Orthodontic Department University of Manchester Dental Hospital and Orthodontic Department Countess of Chester Hospital, United Kingdom. Forty orthodontic patients requiring fixed appliance treatment were enrolled, each being randomly allocated into either NiTi (n = 19) or SS groups (n = 21). Study models were constructed at the start of the space closure phase (T0) and following the completion of space closure (T1). The rate of space closure achieved for each patient was calculated by taking an average measurement from the tip of the canine to the mesiobuccal groove on the first permanent molar of each quadrant. The study was terminated early due to time constraints. Only 30 patients completed, 15 in each study group. There was no statistically significant difference between the amounts of space closed (mean difference 0.17 mm (95%CI -0.99 to 1.34; P = 0.76)). The mean rate of space closure for NiTi coil springs was 0.58 mm/4 weeks (SD 0.24) and 0.85 mm/4 weeks (SD 0.36) for the stainless steel springs. There was a statistically significant difference between the two groups (P = 0.024), in favour of the stainless steel springs, when the mean values per patient were compared. Our study shows that stainless steel springs are clinically effective; these springs produce as much space closure as their more expensive rivals, the NiTi springs.
Ostrik, A. V.; Kazantsev, A. M.
2018-01-01
The problem of principal change of asteroid 99952 (Apophis) orbit is formulated. Aim of this change is the termination of asteroid motion in Solar system. Instead of the passive rescue tactics from asteroid threat, an option is proposed for using the asteroid for setting up a large-scale space experiment on the impact interaction of the asteroid with the Moon. The scientific and methodical apparatus for calculating the possibility of realization, searching and justification the scientific uses of this space experiment is considered.
International Nuclear Information System (INIS)
Weigert, S.
1999-01-01
To reconstruct a mixed or pure quantum state of a spin s is possible through coherent states: its density matrix is fixed by the probabilities to measure the value s along 4s(s+1) appropriately chosen directions in space. Thus, after inverting the experimental data, the statistical operator is parametrized entirely by expectation values. On this basis, a symbolic calculus for quantum spins is developed, the e xpectation-value representation . It resembles the Moyal representation for SU(2) but two important differences exist. On the one hand, the symbols take values on a discrete set of points in phase space only. On the other hand, no quasi-probabilities - that is, phase-space distributions with negative values - are encountered in this approach. (Author)
Directory of Open Access Journals (Sweden)
Zhansheng Li
2014-12-01
Full Text Available Accurate evapotranspiration (ET estimation is very crucial for water resource management, particularly for the arid and semi-arid region. The remote sensing-based Priestley-Taylor method (RS-PT method can estimate ET at regional scale, using the feature space of remotely sensed land surface temperature (LST and vegetation index (VI. This study evaluates the RS-PT feature space method over an arid and semi-arid region in northwest China using satellite data from the moderate-resolution space-borne sensor Advanced Along-Track Scanning Radiometer (AATSR, the observations from the high-resolution airborne sensor Wide-angle Infrared Dual-mode line/area Array Scanner (WiDAS and ground measurements of heat fluxes collected in summer 2008. The results show that the mean difference for latent heat flux (LE estimates resulting from different domain sizes is 69.5 W/m2. When using high-resolution images from airborne measurements, the dry boundary is strongly affected by the pixels of impervious surfaces, which lead to a mean difference of 15.36 W/m2 for LE estimates. In addition, the physically based Surface Energy Balance Index (SEBI model is used to analyze the accuracy of dry/wet boundaries in the RS-PT method. Compared with the SEBI-estimated relative evaporative fraction (Λr, the RS-PT method underestimated Λr by ~0.11. For the RS-PT method, the uncertainty in the determination of the dry/wet boundaries has a significant impact on the accuracy of the ET estimate, not only depending on the size of the area to build the feature space, but also on the land covers.
Chang, Sin-Chung; To, Wai-Ming
1991-01-01
A new numerical framework for solving conservation laws is being developed. It employs: (1) a nontraditional formulation of the conservation laws in which space and time are treated on the same footing, and (2) a nontraditional use of discrete variables such as numerical marching can be carried out by using a set of relations that represents both local and global flux conservation.
Chan, William M.
1992-01-01
This project forms part of the long term computational effort to simulate the time dependent flow over the integrated Space Shuttle vehicle (orbiter, solid rocket boosters (SRB's), external tank (ET), and attach hardware) during its ascent mode for various nominal and abort flight conditions. Due to the limitations of experimental data such as wind tunnel wall effects and the difficulty of safely obtaining valid flight data, numerical simulations are undertaken to supplement the existing data base. This data can then be used to predict the aerodynamic behavior over a wide range of flight conditions. Existing computational results show relatively good overall comparison with experiments but further refinement is required to reduce numerical errors and to obtain finer agreements over a larger parameter space. One of the important goals of this project is to obtain better comparisons between numerical simulations and experiments. In the simulations performed so far, the geometry has been simplified in various ways to reduce the complexity so that useful results can be obtained in a reasonable time frame due to limitations in computer resources. In this project, the finer details of the major components of the Space Shuttle are modeled better by including more complexity in the geometry definition. Smaller components not included in early Space Shuttle simulations will now be modeled and gridded.
Han, Yaohui; Mou, Lan; Xu, Gengchi; Yang, Yiqiang; Ge, Zhenlin
2015-03-01
To construct a three-dimensional finite element model comparing between one-step and two-step methods in torque control of anterior teeth during space closure. Dicom image data including maxilla and upper teeth were obtained though cone-beam CT. A three-dimensional model was set up and the maxilla, upper teeth and periodontium were separated using Mimics software. The models were instantiated using Pro/Engineer software, and Abaqus finite element analysis software was used to simulate the sliding mechanics by loading 1.47 Nforce on traction hooks with different heights (2, 4, 6, 8, 10, 12 and 14 mm, respectively) in order to compare the initial displacement between six maxillary anterior teeth (one-step method) and four maxillary anterior teeth (two-step method). When moving anterior teeth bodily, initial displacements of central incisors in two-step method and in one-step method were 29.26 × 10⁻⁶ mm and 15.75 × 10⁻⁶ mm, respectively. The initial displacements of lateral incisors in two-step method and in one-step method were 46.76 × 10(-6) mm and 23.18 × 10(-6) mm, respectively. Under the same amount of light force, the initial displacement of anterior teeth in two-step method was doubled compared with that in one-step method. The root and crown of the canine couldn't obtain the same amount of displacement in one-step method. Two-step method could produce more initial displacement than one-step method. Therefore, two-step method was easier to achieve torque control of the anterior teeth during space closure.
DEFF Research Database (Denmark)
Lindholst, Andrej Christian; Caspersen, Ole H.; Konijnendijk, Cecil Cornelis
2015-01-01
One of the challenges faced by urban planning is to identify and evaluate recreational and social values of urban and peri-urban green spaces. Over the past 30 years a number of methods for mapping recreational and social values have been developed and implemented in the Nordic countries......, in dialogue between research and urban planning practice. This paper provides a framework for assessment of planning methods and an analysis of the comparative merits of seven Nordic mapping methods and how they address the challenges of identification and evaluation of recreational and social values...
DEFF Research Database (Denmark)
Cujia, Kristian; Wirz, Martin; Kjærgaard, Mikkel Baun
2012-01-01
Fingerprinting-based localization methods relying on WiFi and GSM information provide sufficient localization accuracy for many mobile phone applications. Most of the existing approaches require a training set consisting of geo-referenced fingerprints to build a reference database. We propose...... a collaborative, semi-supervised WiFi+GSM fingerprinting method where only a small fraction of all fingerprints needs to be geo-referenced. Our approach enables indexing of areas in the absence of GPS reception as often found in urban spaces and indoors without manual labeling of fingerprints. The method takes...
Directory of Open Access Journals (Sweden)
Qianqian Yang
2010-01-01
fractional Fokker-Planck equations with a nonlinear source term (TSFFPENST, which involve the Caputo time fractional derivative (CTFD of order ∈ (0, 1 and the symmetric Riesz space fractional derivative (RSFD of order ∈ (1, 2]. Approximating the CTFD and RSFD using the L1-algorithm and shifted Grünwald method, respectively, a computationally effective numerical method is presented to solve the TSFFPE-NST. The stability and convergence of the proposed numerical method are investigated. Finally, numerical experiments are carried out to support the theoretical claims.
Directory of Open Access Journals (Sweden)
Mustafa Inc
2013-01-01
Full Text Available The present paper emphasizes Jeffery-Hamel flow: fluid flow between two rigid plane walls, where the angle between them is 2α. A new method called the reproducing kernel Hilbert space method (RKHSM is briefly introduced. The validity of the reproducing kernel method is set by comparing our results with HAM, DTM, and HPM and numerical results for different values of H, α, and Re. The results show up that the proposed reproducing kernel method can achieve good results in predicting the solutions of such problems. Comparison between obtained results showed that RKHSM is more acceptable and accurate than other methods. This method is very useful and applicable for solving nonlinear problems.
Directory of Open Access Journals (Sweden)
Farshid Mirzaee
2014-06-01
Full Text Available In this paper, we present a numerical method for solving two-dimensional Fredholm–Volterra integral equations (F-VIE. The method reduces the solution of these integral equations to the solution of a linear system of algebraic equations. The existence and uniqueness of the solution and error analysis of proposed method are discussed. The method is computationally very simple and attractive. Finally, numerical examples illustrate the efficiency and accuracy of the method.
Jiang, Hongquan; Zhao, Yalin; Gao, Jianmin; Gao, Zhiyong
2017-06-01
The radiographic testing (RT) image of a steam turbine manufacturing enterprise has the characteristics of low gray level, low contrast, and blurriness, which lead to a substandard image quality. Moreover, it is not conducive for human eyes to detect and evaluate defects. This study proposes an adaptive pseudo-color enhancement method for weld radiographic images based on the hue, saturation, and intensity (HSI) color space and the self-transformation of pixels to solve these problems. First, the pixel's self-transformation is performed to the pixel value of the original RT image. The function value after the pixel's self-transformation is assigned to the HSI components in the HSI color space. Thereafter, the average intensity of the enhanced image is adaptively adjusted to 0.5 according to the intensity of the original image. Moreover, the hue range and interval can be adjusted according to personal habits. Finally, the HSI components after the adaptive adjustment can be transformed to display in the red, green, and blue color space. Numerous weld radiographic images from a steam turbine manufacturing enterprise are used to validate the proposed method. The experimental results show that the proposed pseudo-color enhancement method can improve image definition and make the target and background areas distinct in weld radiographic images. The enhanced images will be more conducive for defect recognition. Moreover, the image enhanced using the proposed method conforms to the human eye visual properties, and the effectiveness of defect recognition and evaluation can be ensured.
Jiang, Hongquan; Zhao, Yalin; Gao, Jianmin; Gao, Zhiyong
2017-06-01
The radiographic testing (RT) image of a steam turbine manufacturing enterprise has the characteristics of low gray level, low contrast, and blurriness, which lead to a substandard image quality. Moreover, it is not conducive for human eyes to detect and evaluate defects. This study proposes an adaptive pseudo-color enhancement method for weld radiographic images based on the hue, saturation, and intensity (HSI) color space and the self-transformation of pixels to solve these problems. First, the pixel's self-transformation is performed to the pixel value of the original RT image. The function value after the pixel's self-transformation is assigned to the HSI components in the HSI color space. Thereafter, the average intensity of the enhanced image is adaptively adjusted to 0.5 according to the intensity of the original image. Moreover, the hue range and interval can be adjusted according to personal habits. Finally, the HSI components after the adaptive adjustment can be transformed to display in the red, green, and blue color space. Numerous weld radiographic images from a steam turbine manufacturing enterprise are used to validate the proposed method. The experimental results show that the proposed pseudo-color enhancement method can improve image definition and make the target and background areas distinct in weld radiographic images. The enhanced images will be more conducive for defect recognition. Moreover, the image enhanced using the proposed method conforms to the human eye visual properties, and the effectiveness of defect recognition and evaluation can be ensured.
Safie, Fayssal M.
1992-01-01
This paper presents a reliability evaluation process designed to improve the reliability of advanced launch systems. The work performed includes the development of a reliability prediction methodology to be used in the design phase of the Space Transportation Main Engine (STME). This includes prediction techniques which use historical data bases as well as deterministic and probabilistic engineering models for predicting design reliability. In summary, this paper describes a probabilistic design approach for the next-generation liquid rocket engine, the STME.
1992-01-01
The technical effort and computer code developed during the first year are summarized. Several formulations for Probabilistic Finite Element Analysis (PFEA) are described with emphasis on the selected formulation. The strategies being implemented in the first-version computer code to perform linear, elastic PFEA is described. The results of a series of select Space Shuttle Main Engine (SSME) component surveys are presented. These results identify the critical components and provide the information necessary for probabilistic structural analysis.
Griko, Yuri; Regan, Matthew D.
2018-02-01
Animal research aboard the Space Shuttle and International Space Station has provided vital information on the physiological, cellular, and molecular effects of spaceflight. The relevance of this information to human spaceflight is enhanced when it is coupled with information gleaned from human-based research. As NASA and other space agencies initiate plans for human exploration missions beyond low Earth orbit (LEO), incorporating animal research into these missions is vitally important to understanding the biological impacts of deep space. However, new technologies will be required to integrate experimental animals into spacecraft design and transport them beyond LEO in a safe and practical way. In this communication, we propose the use of metabolic control technologies to reversibly depress the metabolic rates of experimental animals while in transit aboard the spacecraft. Compared to holding experimental animals in active metabolic states, the advantages of artificially inducing regulated, depressed metabolic states (called synthetic torpor) include significantly reduced mass, volume, and power requirements within the spacecraft owing to reduced life support requirements, and mitigated radiation- and microgravity-induced negative health effects on the animals owing to intrinsic physiological properties of torpor. In addition to directly benefitting animal research, synthetic torpor-inducing systems will also serve as test beds for systems that may eventually hold human crewmembers in similar metabolic states on long-duration missions. The technologies for inducing synthetic torpor, which we discuss, are at relatively early stages of development, but there is ample evidence to show that this is a viable idea and one with very real benefits to spaceflight programs. The increasingly ambitious goals of world's many spaceflight programs will be most quickly and safely achieved with the help of animal research systems transported beyond LEO; synthetic torpor may
Directory of Open Access Journals (Sweden)
Zhang Guowei
2014-01-01
Full Text Available Based on a full-scale bookcase fire experiment, a fire development model is proposed for the whole process of localized fires in large-space buildings. We found that for localized fires in large-space buildings full of wooden combustible materials the fire growing phases can be simplified into a t2 fire with a 0.0346 kW/s2 fire growth coefficient. FDS technology is applied to study the smoke temperature curve for a 2 MW to 25 MW fire occurring within a large space with a height of 6 m to 12 m and a building area of 1 500 m2 to 10 000 m2 based on the proposed fire development model. Through the analysis of smoke temperature in various fire scenarios, a new approach is proposed to predict the smoke temperature curve. Meanwhile, a modified model of steel temperature development in localized fire is built. In the modified model, the localized fire source is treated as a point fire source to evaluate the flame net heat flux to steel. The steel temperature curve in the whole process of a localized fire could be accurately predicted by the above findings. These conclusions obtained in this paper could provide valuable reference to fire simulation, hazard assessment, and fire protection design.
Cort, Cliff
2006-01-01
Education administrators face the dual dilemma of crowded, aging facilities and tightening capital budgets. The challenge is to build the necessary classroom, laboratory and activity space while minimizing the length and expense of the construction process. One solution that offers an affordable alternative is modular construction, a method that…
Schmidt, Alexander H; Stanic, Mijo; Molnár, Imre
2014-03-01
Purity testing of the active pharmaceutical ingredient (API) pramipexole is performed using an official (compendial) and harmonized method published in the European Pharmacopeia (E.P.) and United States Pharmacopeia (USP). According to this monograph the successful chromatographic separation of the API from impurities is achieved on a C18 column with gradient elution of an ion pairing buffer of pH 3.0 (mobile phase A) and acetonitrile (mobile phase B). Although not recommended in general, compendial methods are often adapted for purity testing of generic formulations. In this paper a novel approach to evaluate method robustness of an adapted method - prior of full method validation - is described. Based on Quality-by-Design (QbD) principles, a small number of experiments are performed, which after entering them into a chromatography modeling software allow to visualize a multidimensional "Design Space", a region, in which changes in method parameters will not significantly affect the results as defined in the ICH guideline Q8(R2) leading to a more flexible method handling in routine analysis. For two different recommended C18 columns a multidimensional Design Space (Method Operating Design Region, MODR) was constructed to study the robustness of the adapted method with a newly developed Robustness Module. In a full factorial design the following six parameters were varied at three levels (low, nominal, high): gradient time, temperature, pH of the aqueous eluent (A), flow rate, start- and end concentration of the organic mobile phase component (eluent B). The resulting 3(6)=729 experiments were performed in silico from the previously constructed models for Design Space in less than 1min and showed that the required resolution of 2.0 could not be reached in all experiments for the two columns which were recommended by the E.P. (failure rate 25% and 16%, respectively). However, by adjusting the gradient time, we were able to fulfill the requirements with a failure
Schwandt, Hilary M; Skinner, Joanna; Hebert, Luciana Estelle; Cobb, Lisa; Saad, Abdulmumin; Odeku, Mojisola
2017-09-11
Fertility is high in Nigeria and contraceptive use is low. Little is known about how urban Nigerians perceive the risk of contraceptive use in relation to pregnancy and birth. This study examines and compares the risk perception of family planning methods and pregnancy related scenarios among urban Nigerians. A total of 26 focus group discussions with 243 participants were conducted in September and October 2010 in Ibadan and Kaduna. The groups were stratified by sex, age, family planning use, and city. Study participants were asked to identify the risk associated with six different family planning methods and four pregnancy related risks. The data were coded in ATLAS.ti 6 and analyzed using the thematic content analysis approach. The ten family planning and pregnancy related items ranked as follows from most to least risky: sterilization, abortion, getting pregnant soon after having a baby (no birth spacing), pill, IUD, injectable, having a birth under 18 years of age (teenage motherhood), condom use, having six children, and fertility awareness methods. Risk of family planning methods was often categorized in terms of side effects and complications. Positive perceptions of teenage motherhood and having many children influenced the low ranking of these items. Inadequate birth spacing was rated as more risky than all contraceptive methods and pregnancy related events except for sterilization and abortion. Some of the participants' risk perceptions of contraceptives and pregnancy related scenarios does not correspond to actual risk of methods and practices. Instead, the items' perceived riskiness largely correspond with prevailing social norms. However, there was a high level of understanding of the risks of inadequate birth spacing. This study is not a randomized control trial so the study has not been registered as such.
Jiang, S W; Trujillo, M A; Eberhardt, N L
1996-08-15
Tandemly repeated DNA sequences generated from single synthetic oligonucleotide monomers are useful for many purposes. With conventional ligation procedures low yields and random orientation of oligomers makes cloning of defined repeated sequences difficult. We solved these problems using 2 bp overhangs to direct orientation and random incorporation of linkers containing restriction sites during ligation. Ligation products are amplified by PCR using the linker oligonucleotides as primers. Restriction digestion of the PCR products generate multimer distributions whose length is controlled by the monomer/linker ratio. The concatenated DNA fragments of defined length, orientation and spacing can be directly used for subcloning or other applications without further treatment.
International Nuclear Information System (INIS)
Gorbunova, Eh.M.; Ivanchenko, G.N.
2004-01-01
Performance of underground nuclear explosions (UNE) leads to irreversible changes in geological environment around the boreholes. In natural environment it was detected inhomogeneity of rock massif condition changes, which depended on characteristics of the underground nuclear explosion, anisotropy of medium and presence of faulting. Application of automated selection and statistic analysis of unstretched lineaments in high resolution space images using special software pack LESSA allows specifying the geologic-structural features of Semipalatinsk Test Site (STS), ranging selected fracture zones, outlining and analyzing post-explosion zone surface deformations. (author)
Directory of Open Access Journals (Sweden)
Yan Tang
2013-01-01
Full Text Available Suppose that C is a nonempty closed convex subset of a real reflexive Banach space E which has a uniformly Gateaux differentiable norm. A viscosity iterative process is constructed in this paper. A strong convergence theorem is proved for a common element of the set of fixed points of a finite family of pseudocontractive mappings and the set of solutions of a finite family of monotone mappings. And the common element is the unique solution of certain variational inequality. The results presented in this paper extend most of the results that have been proposed for this class of nonlinear mappings.
Simon, Geoffroy; Lendasse, Amaury; Cottrell, Marie; Fort, Jean-Claude; Verleysen, Michel
2004-01-01
The Kohonen self-organization map is usually considered as a classification or clustering tool, with only a few applications in time series prediction. In this paper, a particular time series forecasting method based on Kohonen maps is described. This method has been specifically designed for the prediction of long-term trends. The proof of the stability of the method for long-term forecasting is given, as well as illustrations of the utilization of the method both in the scalar and vectorial cases.
Zhang, Su-Jing; Shen, Bao-Hua; Zhuo, Xian-Yi
2013-04-01
To develop a simple, validated method for identifying and quantifying 1,3-butadiene (BD) in human blood by gas chromatography-mass spectrometry (GC-MS) and head-space gas chromatography (HS-GC). BD was identified by GC-MS and HS-GC, and quantified by HS-GC. The method showed that BD had a good linearity from 50 to 500 microg/mL (r > 0.99). The limits of detection and quantification were 10 microg/mL and 50 microg/mL, respectively. Both the intra-day precision and inter-day precision were < 6.08%, and the accuracy was 96.98%-103.81%. The method was applied to an actual case, and the concentration of BD in the case was 242 microg/mL in human blood. This simple method is found to be useful for the routine forensic analysis of acute exposure to BD.
Chattopadhyay, Sudip; Chaudhuri, Rajat K; Freed, Karl F
2011-04-28
The improved virtual orbital (IVO) complete active space (CAS) configuration interaction (IVO-CASCI) method is a simplified CAS self-consistent field (SCF), CASSCF, method. Unlike the CASSCF approach, the IVO-CASCI method does not require iterations beyond an initial SCF calculation, rendering the IVO-CASCI scheme computationally more tractable than the CASSCF method and devoid of the convergence problems that sometimes plague CASSCF calculations as the CAS size increases, while retaining all the essential positive benefits of the CASSCF method. Earlier applications demonstrate that the IVO-CASCI energies are at least as accurate as those from the CASSCF and provide the impetus for our recent development of the analytical derivative procedures that are necessary for a wide applicability of the IVO-CASCI approach. Here we test the ability of the analytic energy gradient IVO-CASCI approach (which can treat both closed- and open-shell molecules of arbitrary spin multiplicity) to compute the equilibrium geometries of four organic radicaloid species, namely, (i) the diradicals trimethylenemethane (TMM), 2,6-pyridyne, and the 2,6-pyridynium cation and (ii) a triradical 1,2,3-tridehydrobenzene (TDB), using various basis sets and different choices for the active space. Although these systems and related molecules have fascinated theoretical chemists for many years, their strong multireference character makes their description quite difficult with most standard many-body approaches. Thus, they provide ideal tests to assess the performance of the IVO-CASCI method. The present work demonstrates consistent agreement with far more expensive benchmark state-of-the-art ab initio calculations and thereby indicates that this new gradient method is able to describe the geometries of various radicaloids very accurately, even when small, but qualitatively correct, reference spaces are used. For example, the IVO-CASCI method leads to a monocyclic structure for the 2,6-isomers of the
Tishkin, S S
2001-01-01
In the paper the procedure of solving integral equations with the use of auxiliary charges is used. The electrostatic field potential is presented in the form of superposition of the fields of point sources located out of the investigated region at some distance from it. The values of N charges are determined from the boundary conditions at N points of the boundary. The definition of the point sources is equivalent to using some function of the charge density at the boundary of the region.This approach was used for the calculation of structures with the space-uniform quadruple focusing with sinusoidal and trapezoidal modulation, and also a section of the transverse matching of the 'funnel'.
Ren, Kai; Xu, Leiqing
2017-10-01
The data related in this paper are related to "Environmental-behavior studies of sustainable construction of the third place - based on outdoor environment-behavior cross-feed symbiotic analysis and verification of selective activities" (Ren, 2017) [1]. The dataset was from a field sub-time extended investigation to children of Hohhot West Inner Mongolia Electric Power Community Residential Area in Inner Mongolia of China that belongs to cold region of ID area according to Chinese design code for buildings. This filed data provided descriptive statistics about outdoor time, behavior scale specificity, age exclusivity and self-centeredness for children in different ages (babies, preschool children, school age children). This data provided five measurement elements of child-friendly space and their weight ratio. The field data set is made publicly available to enable critical or extended analyzes.
Blumenstock, Kenneth A.
2017-01-01
Throughout the history of the Hubble Space Telescope (HST) program, gyro current increases have been observed to occur, oftentimes leading to gyro failure. The explanation was that debris from the surfaces of the gas bearings, with only 50 millionths on an inch clearance, resulted in rotor restriction, which increased friction, torque, and current. However, the rotor restriction theory never could account for the fact that a restart of the gyro would restore the current back to nominal. An effort was made to understand this puzzling gyro behavior after two HST gyros exhibited increased current within the same week in November 2015. A review board was created to resolve these anomalies and generate operational procedures to potentially extend gyro life.
DEFF Research Database (Denmark)
Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth
2015-01-01
The increasing number of renewable energy sources at the distribution grid is becoming a major issue for utility companies, since the grid connected converters are operating at different operating points due to the probabilistic characteristics of renewable energy. Besides, typically, the harmonics...... proposes a new model of a single phase grid connected renewable energy source using the Harmonic State Space modeling approach, which is able to identify such problems and the model can be extended to be applied in the multiple connected converter analysis. The modeling results show the different harmonic...... and impedance from other renewable energy sources are not taken carefully into account in the installation and design. However, this may bring an unknown harmonic instability into the multiple power sourced system and also make the analysis difficult due to the complexity of the grid network. This paper...
Sugimoto, Nobuo; Minato, Atsushi; Sasano, Yasuhiro
1992-01-01
The Retroreflector in Space (RIS) is a single element cube-corner retroreflector with a diameter of 0.5 m designed for earth-satellite-earth laser long-path absorption experiments. The RIS is to be loaded on the Advanced Earth Observing System (ADEOS) satellite which is scheduled for launch in Feb. 1996. The orbit for ADEOS is a sun synchronous subrecurrent polar-orbit with an inclination of 98.6 deg. It has a period of 101 minutes and an altitude of approximately 800 km. The local time at descending node is 10:15-10:45, and the recurrent period is 41 days. The velocity relative to the ground is approximately 7 km/s. In the RIS experiment, a laser beam transmitted from a ground station is reflected by RIS and received at the ground station. The absorption of the intervening atmosphere is measured in the round-trip optical path.
A Two-Stage Space-Time Adaptive Processing Method for MIMO Radar Based on Sparse Reconstruction
Liu, Hanwei; Zhang, Yongshun; Guo, Yiduo; Wang, Qiang
2017-10-01
To effectively suppress clutter and blocking interference for MIMO radar, a two-stage STAP method based on sparse reconstruction is proposed. As interference is sparse in spatial domain, the subspace of it is estimated with only one snapshot by using Orthogonal Matching Pursuit (OMP) algorithm, and the array data is projected onto the complementary subspace of interference. In the sequel, matched-filtering is applied to the output data followed by clutter suppression with temporal and spatial freedom. The clutter suppression is utilized directly to reduced-dimension STAP (RD-STAP) algorithms. Simulation results demonstrate that the proposed method outperforms traditional methods and reduces sample requirement.
International Nuclear Information System (INIS)
Itagaki, M.; Brebbia, C.A.
1991-01-01
This paper reports on the boundary element method used to generate energy-dependent matrix-type boundary conditions along core/reflector interfaces and along baffle-plate surfaces of pressurized water reactors. This method enables one to deal with all types of boundary geometries including convex and concave corners. The method is applicable to neutron diffusion problems with more than two energy groups and also can be used to model a reflector with or without a baffle plate. Excellent eigenvalue and flux shape results can be obtained when the boundary conditions generated by this technique are coupled with core-only finite difference calculations
Fixed point theorems in locally convex spacesÃ¢Â€Â”the Schauder mapping method
Directory of Open Access Journals (Sweden)
S. Cobzaş
2006-03-01
Full Text Available In the appendix to the book by F. F. Bonsal, Lectures on Some Fixed Point Theorems of Functional Analysis (Tata Institute, Bombay, 1962 a proof by Singbal of the Schauder-Tychonoff fixed point theorem, based on a locally convex variant of Schauder mapping method, is included. The aim of this note is to show that this method can be adapted to yield a proof of Kakutani fixed point theorem in the locally convex case. For the sake of completeness we include also the proof of Schauder-Tychonoff theorem based on this method. As applications, one proves a theorem of von Neumann and a minimax result in game theory.
International Nuclear Information System (INIS)
Wiener, M.C.; White, S.H.
1991-01-01
This is the second of two papers describing a method for the joint refinement of the structure of fluid bilayers using x-ray and neutron diffraction data. We showed in the first paper that fluid bilayers generally consist of a nearly perfect lattice of thermally disordered unit cells and that the canonical resolution d/hmax is a measure of the widths of quasimolecular components represented by simple Gaussian functions. The thermal disorder makes possible a 'composition space' representation in which the quasimolecular Gaussian distributions describe the number or probability of occupancy per unit length across the width of the bilayer of each component. This representation permits the joint refinement of neutron and x-ray lamellar diffraction data by means of a single quasimolecular structure that is fit simultaneously to both diffraction data sets. Scaling of each component by the appropriate neutron or x-ray scattering length maps the composition space profile to the appropriate scattering length space for comparison to experimental data. Other extensive properties, such as mass, can also be obtained by an appropriate scaling of the refined composition space structure. Based upon simple bilayer models involving crystal and liquid crystal structural information, we estimate that a fluid bilayer with hmax observed diffraction orders will be accurately represented by a structure with approximately hmax quasimolecular components. Strategies for assignment of quasimolecular components are demonstrated through detailed parsing of a phospholipid molecule based upon the one-dimensional projection of the crystal structure of dimyristoylphosphatidylcholine. Finally, we discuss in detail the number of experimental variables required for the composition space joint refinement. We find fluid bilayer structures to be marginally determined by the experimental data
Wiener, M C; White, S H
1991-01-01
This is the second of two papers describing a method for the joint refinement of the structure of fluid bilayers using x-ray and neutron diffraction data. We showed in the first paper (Wiener, M. C., and S. H. White. 1990. Biophys. J. 59:162-173) that fluid bilayers generally consist of a nearly perfect lattice of thermally disordered unit cells and that the canonical resolution d/hmax is a measure of the widths of quasimolecular components represented by simple Gaussian functions. The thermal disorder makes possible a "composition space" representation in which the quasimolecular Gaussian distributions describe the number or probability of occupancy per unit length across the width of the bilayer of each component. This representation permits the joint refinement of neutron and x-ray lamellar diffraction data by means of a single quasimolecular structure that is fit simultaneously to both diffraction data sets. Scaling of each component by the appropriate neutron or x-ray scattering length maps the composition space profile to the appropriate scattering length space for comparison to experimental data. Other extensive properties, such as mass, can also be obtained by an appropriate scaling of the refined composition space structure. Based upon simple bilayer models involving crystal and liquid crystal structural information, we estimate that a fluid bilayer with hmax observed diffraction orders will be accurately represented by a structure with approximately hmax quasimolecular components. Strategies for assignment of quasimolecular components are demonstrated through detailed parsing of a phospholipid molecule based upon the one-dimensional projection of the crystal structure of dimyristoylphosphatidylcholine. Finally, we discuss in detail the number of experimental variables required for the composition space joint refinement. We find fluid bilayer structures to be marginally determined by the experimental data. The analysis of errors, which takes on particular
Peng, Bo; Zheng, Sifa; Liao, Xiangning; Lian, Xiaomin
2018-03-01
In order to achieve sound field reproduction in a wide frequency band, multiple-type speakers are used. The reproduction accuracy is not only affected by the signals sent to the speakers, but also depends on the position and the number of each type of speaker. The method of optimizing a mixed speaker array is investigated in this paper. A virtual-speaker weighting method is proposed to optimize both the position and the number of each type of speaker. In this method, a virtual-speaker model is proposed to quantify the increment of controllability of the speaker array when the speaker number increases. While optimizing a mixed speaker array, the gain of the virtual-speaker transfer function is used to determine the priority orders of the candidate speaker positions, which optimizes the position of each type of speaker. Then the relative gain of the virtual-speaker transfer function is used to determine whether the speakers are redundant, which optimizes the number of each type of speaker. Finally the virtual-speaker weighting method is verified by reproduction experiments of the interior sound field in a passenger car. The results validate that the optimum mixed speaker array can be obtained using the proposed method.
Wang, Xiao-Yen; Chang, Sin-Chung; Jorgenson, Philip C. E.
2000-01-01
The benchmark problems in Category 1 (Internal Propagation) of the third Computational Aeroacoustics (CAA) Work-shop sponsored by NASA Glenn Research Center are solved using the space-time conservation element and solution element (CE/SE) method. The first problem addresses the propagation of sound waves through a nearly choked transonic nozzle. The second one concerns shock-sound interaction in a supersonic nozzle. A quasi one-dimension CE/SE Euler solver for a nonuniform mesh is developed and employed to solve both problems. Numerical solutions are compared with the analytical solution for both problems. It is demonstrated that the CE/SE method is capable of solving aeroacoustic problems with/without shock waves in a simple way. Furthermore, the simple nonreflecting boundary condition used in the CE/SE method which is not based on the characteristic theory works very well.
Patterson, Toey A; McConnell, Bernie J; Fedak, Mike A; Bravington, Mark V; Hindell, Mark A
2010-01-01
Recent studies have applied state-space models to satellite telemetry data in order to remove noise from raw location estimates and infer the true tracks of animals. However, while the resulting tracks may appear plausible, it is difficult to determine the accuracy of the estimated positions, especially for position estimates interpolated to times between satellite locations. In this study, we use data from two gray seals (Halichoerus grypus) carrying tags that transmitted Fastloc GPS positions via Argos satellites. This combination of Service Argos data and highly accurate GPS data allowed examination of the accuracy of state-space position estimates and their uncertainty derived from satellite telemetry data. After applying a speed filter to remove aberrant satellite telemetry locations, we fit a continuous-time Kalman filter to estimate the parameters of a random walk, used Kalman smoothing to infer positions at the times of the GPS measurements, and then compared the filtered telemetry estimates with the actual GPS measurements. We investigated the effect of varying maximum speed thresholds in the speed-filtering algorithm on the root mean-square error (RMSE) estimates and used minimum RMSE as a criterion to guide the final choice of speed threshold. The optimal speed thresholds differed between the two animals (1.1 m/s and 2.5 m/s) and retained 50% and 65% of the data for each seal. However, using a speed filter of 1.1 m/s resulted in very similar RMSE for both animals. For the two seals, the RMSE of the Kalman-filtered estimates of location were 5.9 and 12.76 km, respectively, and 75% of the modeled positions had errors less than 6.25 km and 11.7 km for each seal. Confidence interval coverage was close to correct at typical levels (80-95%), although it tended to be overly generous at smaller sizes. The reliability of uncertainty estimates was also affected by the chosen speed threshold. The combination of speed and Kalman filtering allows for effective
Accomando, Alyssa W.; Vargas-Irwin, Carlos E.; Simmons, James A.
2018-01-01
Bats emit biosonar pulses in complex temporal patterns that change to accommodate dynamic surroundings. Efforts to quantify these patterns have included analyses of inter-pulse intervals, sonar sound groups, and changes in individual signal parameters such as duration or frequency. Here, the similarity in temporal structure between trains of biosonar pulses is assessed. The spike train similarity space (SSIMS) algorithm, originally designed for neural activity pattern analysis, was applied to determine which features of the environment influence temporal patterning of pulses emitted by flying big brown bats, Eptesicus fuscus. In these laboratory experiments, bats flew down a flight corridor through an obstacle array. The corridor varied in width (100, 70, or 40 cm) and shape (straight or curved). Using a relational point-process framework, SSIMS was able to discriminate between echolocation call sequences recorded from flights in each of the corridor widths. SSIMS was also able to tell the difference between pulse trains recorded during flights where corridor shape through the obstacle array matched the previous trials (fixed, or expected) as opposed to those recorded from flights with randomized corridor shape (variable, or unexpected), but only for the flight path shape in which the bats had previous training. The results show that experience influences the temporal patterns with which bats emit their echolocation calls. It is demonstrated that obstacle proximity to the bat affects call patterns more dramatically than flight path shape. PMID:29472848
Directory of Open Access Journals (Sweden)
Jonathas Magalhães Pereira da Silva
2014-12-01
Full Text Available Considering the contemporary practices of teaching in Project and in Urban and Regional Planning this text aims to share the teaching experience developed between 2009 and 2012 at FAU PUC-Campinas. The article presents the procedures and attitudinal postures adopted in the classroom detailing the development stages, the arguments and results. The text search, through the teaching experience systematization, the construction of an interdisciplinary dialogue which sets out clearly the progress when the open spaces system is considered in the territorial planning process. The proposed exercise aims to question the contemporary territorial processes occupation conditioned by a logic where the individual transport is dominant and the absence of a territorial structuring. The discipline is not to be limited to exploit for professional practice, but provoke a reflective practice based on the construction of arguments that reveal themselves in drawings considering the different scales, the interests of different actors, the contradictions and the history of the discipline. The landscape design is used here as an instrument of reflection that contests the reality and creates arguments for new urban spatial configurations.
KOK, LP; SCHELLINGERHOUT, NW
1991-01-01
The three-body problem is solved at negative energies using the Faddeev-Noyes equations. The latter are reduced to a matrix equation by spline approximation and orthogonal collocation. This matrix equation is solved using a method that is based on the tensor structure of the matrices. High-accuracy
International Nuclear Information System (INIS)
Shieh, Chun-Chien; Kipritidis, John; O’Brien, Ricky T.; Keall, Paul J.; Kuncic, Zdenka
2014-01-01
Purpose: Respiratory signal, binning method, and reconstruction algorithm are three major controllable factors affecting image quality in thoracic 4D cone-beam CT (4D-CBCT), which is widely used in image guided radiotherapy (IGRT). Previous studies have investigated each of these factors individually, but no integrated sensitivity analysis has been performed. In addition, projection angular spacing is also a key factor in reconstruction, but how it affects image quality is not obvious. An investigation of the impacts of these four factors on image quality can help determine the most effective strategy in improving 4D-CBCT for IGRT. Methods: Fourteen 4D-CBCT patient projection datasets with various respiratory motion features were reconstructed with the following controllable factors: (i) respiratory signal (real-time position management, projection image intensity analysis, or fiducial marker tracking), (ii) binning method (phase, displacement, or equal-projection-density displacement binning), and (iii) reconstruction algorithm [Feldkamp–Davis–Kress (FDK), McKinnon–Bates (MKB), or adaptive-steepest-descent projection-onto-convex-sets (ASD-POCS)]. The image quality was quantified using signal-to-noise ratio (SNR), contrast-to-noise ratio, and edge-response width in order to assess noise/streaking and blur. The SNR values were also analyzed with respect to the maximum, mean, and root-mean-squared-error (RMSE) projection angular spacing to investigate how projection angular spacing affects image quality. Results: The choice of respiratory signals was found to have no significant impact on image quality. Displacement-based binning was found to be less prone to motion artifacts compared to phase binning in more than half of the cases, but was shown to suffer from large interbin image quality variation and large projection angular gaps. Both MKB and ASD-POCS resulted in noticeably improved image quality almost 100% of the time relative to FDK. In addition, SNR
Morand, Josselin; Moss, Raymond; Hachem, Sabet; Sauerwein, Wolfgang
2009-07-01
This work provides the basis of a methodology to build a deterministic model for the spatial distribution of the (10)B(n,alpha)(7)Li reaction rate in boron neutron capture therapy (BNCT), as a function of space variables, boron concentration and beam incidence angle in homogeneous isotropic environments but also in different heterogeneous environments. Building the analytic function in a simple homogeneous environment with numerical methods leads to a mathematical formulation of the (10)B(n,alpha)(7)Li reactions rate.
Habboush, Nawar; Hamid, Laith; Japaridze, Natia; Wiegand, Gert; Heute, Ulrich; Stephani, Ulrich; Galka, Andreas; Siniatchkin, Michael
2015-08-01
The discretization of the brain and the definition of the Laplacian matrix influence the results of methods based on spatial and spatio-temporal smoothness, since the Laplacian operator is used to define the smoothness based on the neighborhood of each grid point. In this paper, the results of low resolution electromagnetic tomography (LORETA) and the spatiotemporal Kalman filter (STKF) are computed using, first, a greymatter source space with the standard definition of the Laplacian matrix and, second, using a whole-brain source space and a modified definition of the Laplacian matrix. Electroencephalographic (EEG) source imaging results of five inter-ictal spikes from a pre-surgical patient with epilepsy are used to validate the two aforementioned approaches. The results using the whole-brain source space and the modified definition of the Laplacian matrix were concentrated in a single source activation, stable, and concordant with the location of the focal cortical dysplasia (FCD) in the patient's brain compared with the results which use a grey-matter grid and the classical definition of the Laplacian matrix. This proof-of-concept study demonstrates a substantial improvement of source localization with both LORETA and STKF and constitutes a basis for further research in a large population of patients with epilepsy.
Space and Time Adaptive Two-Mesh hp-Finite Element Method for Transient Microwave Heating Problems
Czech Academy of Sciences Publication Activity Database
Dubcová, Lenka; Šolín, Pavel; Červený, Jakub; Kůs, Pavel
1-2, č. 30 (2010), s. 23-40 ISSN 0272-6343 R&D Projects: GA ČR(CZ) GA102/07/0496; GA AV ČR IAA100760702 Institutional research plan: CEZ:AV0Z20570509 Keywords : hp-finite element method * microwave heating * edge elements Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.844, year: 2010
Directory of Open Access Journals (Sweden)
R. Talebitooti
Full Text Available In this paper the effect of quadratic and cubic non-linearities of the system consisting of the crankshaft and torsional vibration damper (TVD is taken into account. TVD consists of non-linear elastomer material used for controlling the torsional vibration of crankshaft. The method of multiple scales is used to solve the governing equations of the system. Meanwhile, the frequency response of the system for both harmonic and sub-harmonic resonances is extracted. In addition, the effects of detuning parameters and other dimensionless parameters for a case of harmonic resonance are investigated. Moreover, the external forces including both inertia and gas forces are simultaneously applied into the model. Finally, in order to study the effectiveness of the parameters, the dimensionless governing equations of the system are solved, considering the state space method. Then, the effects of the torsional damper as well as all corresponding parameters of the system are discussed.
Macías-Díaz, J. E.
2017-12-01
In this manuscript, we consider an initial-boundary-value problem governed by a (1 + 1)-dimensional hyperbolic partial differential equation with constant damping that generalizes many nonlinear wave equations from mathematical physics. The model considers the presence of a spatial Laplacian of fractional order which is defined in terms of Riesz fractional derivatives, as well as the inclusion of a generic continuously differentiable potential. It is known that the undamped regime has an associated positive energy functional, and we show here that it is preserved throughout time under suitable boundary conditions. To approximate the solutions of this model, we propose a finite-difference discretization based on fractional centered differences. Some discrete quantities are proposed in this work to estimate the energy functional, and we show that the numerical method is capable of conserving the discrete energy under the same boundary conditions for which the continuous model is conservative. Moreover, we establish suitable computational constraints under which the discrete energy of the system is positive. The method is consistent of second order, and is both stable and convergent. The numerical simulations shown here illustrate the most important features of our numerical methodology.
Vivodtzev, Fabien; Pascucci, Valerio
2015-01-01
This book contains papers presented at the Workshop on the Analysis of Large-scale, High-Dimensional, and Multi-Variate Data Using Topology and Statistics, held in Le Barp, France, June 2013. It features the work of some of the most prominent and recognized leaders in the field who examine challenges as well as detail solutions to the analysis of extreme scale data. The book presents new methods that leverage the mutual strengths of both topological and statistical techniques to support the management, analysis, and visualization of complex data. It covers both theory and application and provides readers with an overview of important key concepts and the latest research trends. Coverage in the book includes multi-variate and/or high-dimensional analysis techniques, feature-based statistical methods, combinatorial algorithms, scalable statistics algorithms, scalar and vector field topology, and multi-scale representations. In addition, the book details algorithms that are broadly applicable and can be us...
Chang, Sin-Chung; Wang, Xiao-Yen; Chow, Chuen-Yen
1994-01-01
A new numerical discretization method for solving conservation laws is being developed. This new approach differs substantially in both concept and methodology from the well-established methods, i.e., finite difference, finite volume, finite element, and spectral methods. It is motivated by several important physical/numerical considerations and designed to avoid several key limitations of the above traditional methods. As a result of the above considerations, a set of key principles for the design of numerical schemes was put forth in a previous report. These principles were used to construct several numerical schemes that model a 1-D time-dependent convection-diffusion equation. These schemes were then extended to solve the time-dependent Euler and Navier-Stokes equations of a perfect gas. It was shown that the above schemes compared favorably with the traditional schemes in simplicity, generality, and accuracy. In this report, the 2-D versions of the above schemes, except the Navier-Stokes solver, are constructed using the same set of design principles. Their constructions are simplified greatly by the use of a nontraditional space-time mesh. Its use results in the simplest stencil possible, i.e., a tetrahedron in a 3-D space-time with a vertex at the upper time level and other three at the lower time level. Because of the similarity in their design, each of the present 2-D solvers virtually shares with its 1-D counterpart the same fundamental characteristics. Moreover, it is shown that the present Euler solver is capable of generating highly accurate solutions for a famous 2-D shock reflection problem. Specifically, both the incident and the reflected shocks can be resolved by a single data point without the presence of numerical oscillations near the discontinuity.
Zhang, Zeng-Chan; Yu, S. T. John; Chang, Sin-Chung; Jorgenson, Philip (Technical Monitor)
2001-01-01
In this paper, we report a version of the Space-Time Conservation Element and Solution Element (CE/SE) Method in which the 2D and 3D unsteady Euler equations are simulated using structured or unstructured quadrilateral and hexahedral meshes, respectively. In the present method, mesh values of flow variables and their spatial derivatives are treated as independent unknowns to be solved for. At each mesh point, the value of a flow variable is obtained by imposing a flux conservation condition. On the other hand, the spatial derivatives are evaluated using a finite-difference/weighted-average procedure. Note that the present extension retains many key advantages of the original CE/SE method which uses triangular and tetrahedral meshes, respectively, for its 2D and 3D applications. These advantages include efficient parallel computing ease of implementing non-reflecting boundary conditions, high-fidelity resolution of shocks and waves, and a genuinely multidimensional formulation without using a dimensional-splitting approach. In particular, because Riemann solvers, the cornerstones of the Godunov-type upwind schemes, are not needed to capture shocks, the computational logic of the present method is considerably simpler. To demonstrate the capability of the present method, numerical results are presented for several benchmark problems including oblique shock reflection, supersonic flow over a wedge, and a 3D detonation flow.
Energy Technology Data Exchange (ETDEWEB)
Korotkin, Ivan, E-mail: i.korotkin@qmul.ac.uk; Karabasov, Sergey; Markesteijn, Anton [The School of Engineering and Material Science, Queen Mary University of London, Mile End Road, E1 4NS London (United Kingdom); Nerukh, Dmitry; Scukins, Arturs [Institute of Systems Analytics, Aston University, Birmingham B4 7ET (United Kingdom); Farafonov, Vladimir [Department of Physical Chemistry, V. N. Karazin Kharkiv National University, Svobody Square 4, 61022 Kharkiv (Ukraine); Pavlov, Evgen [Institute of Systems Analytics, Aston University, Birmingham B4 7ET (United Kingdom); Faculty of Physics, Kiev National Taras Shevchenko University, Prospect Acad. Glushkova 4, Kiev 03127 (Ukraine)
2015-07-07
A new 3D implementation of a hybrid model based on the analogy with two-phase hydrodynamics has been developed for the simulation of liquids at microscale. The idea of the method is to smoothly combine the atomistic description in the molecular dynamics zone with the Landau-Lifshitz fluctuating hydrodynamics representation in the rest of the system in the framework of macroscopic conservation laws through the use of a single “zoom-in” user-defined function s that has the meaning of a partial concentration in the two-phase analogy model. In comparison with our previous works, the implementation has been extended to full 3D simulations for a range of atomistic models in GROMACS from argon to water in equilibrium conditions with a constant or a spatially variable function s. Preliminary results of simulating the diffusion of a small peptide in water are also reported.
Perisic, Milun; Kinoshita, Michael H; Ranson, Ray M; Gallegos-Lopez, Gabriel
2014-06-03
Methods, system and apparatus are provided for controlling third harmonic voltages when operating a multi-phase machine in an overmodulation region. The multi-phase machine can be, for example, a five-phase machine in a vector controlled motor drive system that includes a five-phase PWM controlled inverter module that drives the five-phase machine. Techniques for overmodulating a reference voltage vector are provided. For example, when the reference voltage vector is determined to be within the overmodulation region, an angle of the reference voltage vector can be modified to generate a reference voltage overmodulation control angle, and a magnitude of the reference voltage vector can be modified, based on the reference voltage overmodulation control angle, to generate a modified magnitude of the reference voltage vector. By modifying the reference voltage vector, voltage command signals that control a five-phase inverter module can be optimized to increase output voltages generated by the five-phase inverter module.
Directory of Open Access Journals (Sweden)
Grażyna Łaska
2015-09-01
Full Text Available The study aimed at evaluation of the current state and description of changes in plant communities in wetland habitats in the Czarna river valley and at recommendation of effective methods for the renewal of vegetation on the basis of detail analysis of its space-time changes. The methods applied included a compilation of field studies (inventory, cartographic study and phytosociological analyses, valorisation of nature, numerical syntaxonomy with the use of MVSP program (Cluster Analysis and PCA and digital methods GIS (Geomedia Professional 6.1. The field study of the vegetation cover of the Czarna river valley was performed in the years 2010–2011. The space-time analysis of changes in the vegetation cover and renewal of vegetation was made with the use of archive aerial photographs from 1966, topographic maps from 1982 and 2000 and orthophotomaps from 2011. The vegetation cover of the Czarna river valley was found to be composed of 12 plant communities representing 6 syntaxonomic classes, and to include sites of 8 protected species. The space-time analysis of the vegetation cover of the Czarna river valley, taking into account the changes in the forms of the valley use over the period 1966–2011, showed that the area occupied by forest communities in wetland habitats as a result of secondary succession has increased by 0.16 km2, so by 27% with respect to the area of 0.4406 km2 from 1966. Chronological changes in the vegetation cover over this area analysed on the basis of GIS and digital methods indicate that in the wet meadows in the valley studied the secondary succession leads to the reproduction of the potential forest communities that were growing there once in the past. The renewal of forestless greeneries in the Czarna river valley is related to changes in the use of the area realised by mowing and restoration of the earlier hydrological regime in the entire catchment area, changed by the network of channels and drainage ditches.
Ben Regaya, Chiheb; Farhani, Fethi; Zaafouri, Abderrahmen; Chaari, Abdelkader
2018-02-01
This paper presents a new adaptive Backstepping technique to handle the induction motor (IM) rotor resistance tracking problem. The proposed solution leads to improve the robustness of the control system. Given the presence of static error when estimating the rotor resistance with classical methods, and the sensitivity to the load torque variation at low speed, a new Backstepping observer enhanced with an integral action of the tracking errors is presented, which can be established in two steps. The first one consists to estimate the rotor flux using a Backstepping observer. The second step, defines the adaptation mechanism of the rotor resistance based on the estimated rotor-flux. The asymptotic stability of the observer is proven by Lyapunov theory. To validate the proposed solution, a simulation and experimental benchmarking of a 3 kW induction motor are presented and analyzed. The obtained results show the effectiveness of the proposed solution compared to the model reference adaptive system (MRAS) rotor resistance observer presented in other recent works.
Cheng, Jianjun; Jin, Ke; Kou, Yong; Hu, Ruifeng; Zheng, Xiaojing
2017-03-01
When a hypersonic vehicle travels in the Earth and Mars atmosphere, the surface of the vehicle is surrounded by a plasma layer, which is an envelope of ionized air, created from the compression and heat of the atmosphere by the shock wave. The vehicles will lose contact with ground stations known as the reentry communication blackout. Based on the magnetohydrodynamic framework and electromagnetic wave propagation theory, an analytical model is proposed to describe the effect of the effectiveness of electromagnetic mitigation scheme on removing the reentry communication blackout. C and Global Positioning System (GPS) bands, two commonly used radio bands for communication, are taken as the cases to discuss the effectiveness of the electromagnetic field mitigation scheme. The results show that the electron density near the antenna of vehicles can be reduced by the electromagnetic field, and the required external magnetic field strength is far below the one in the magnetic window method. The directions of the external electric field and magnetic field have a significant impact on the effectiveness of the mitigation scheme. Furthermore, the effect of electron collisions on the required applied electromagnetic field is discussed, and the result indicates that electron collisions are a key factor to analyze the electromagnetic mitigation scheme. Finally, the feasible regions of the applied electromagnetic field for eliminating blackout are given. These investigations could have a significant benefit on the design and optimization of electromagnetic mitigation scheme for the blackout problem.
Ball, Natalie; Kagawa, Hiromi; Hindupur, Aditya; Hogan, John
2017-01-01
Long-duration space missions will benefit from closed-loop life support technologies that minimize mass, volume, and power as well as decrease reliance on Earth-based resupply. A system for In situ production of essential vitamins and nutrients can address the documented problem of degradation of stored food and supplements. Research has shown that the edible yeast Saccharomyces cerevisiae can be used as an on-demand system for the production of various compounds that are beneficial to human health. A critical objective in the development of this approach for long-duration space missions is the effective storage of the selected microorganisms. This research investigates the effects of different storage methods on survival rates of the non-sporulating probiotic S. boulardii, and S. cerevisiae spores and vegetative cells. Dehydration has been shown to increase long-term yeast viability, which also allows increased shelf-life and reduction in mass and volume. The process of dehydration causes detrimental effects on vegetative cells, including oxidative damage and membrane disruption. To maximize cell viability, various dehydration methods are tested here, including lyophilization (freeze-drying), air drying, and dehydration by vacuum. As a potential solution to damage caused by lyophilization, the efficacy of various cryoprotectants was tested. Furthermore, in an attempt to maintain higher survival rates, the effect of temperature during long-term storage was investigated. Data show spores of the wild-type strain to be more resilient to dehydration-related stressors than vegetative cells of either strain, and maintain high viability rates even after one year at room temperature. In the event that engineering the organism to produce targeted nutrient compounds interferes with effective sporulation of S. cerevisiae, a more robust method for improving vegetative cell storage is being sought. Therefore, anhydrobiotic engineering of S. cerevisiae and S. boulardii is being
Directory of Open Access Journals (Sweden)
Ling Fiona W.M.
2017-01-01
Full Text Available Rapid prototyping of microchannel gain lots of attention from researchers along with the rapid development of microfluidic technology. The conventional methods carried few disadvantages such as high cost, time consuming, required high operating pressure and temperature and involve expertise in operating the equipment. In this work, new method adapting xurography method is introduced to replace the conventional method of fabrication of microchannels. The novelty in this study is replacing the adhesion film with clear plastic film which was used to cut the design of the microchannel as the material is more suitable for fabricating more complex microchannel design. The microchannel was then mold using polymethyldisiloxane (PDMS and bonded with a clean glass to produce a close microchannel. The microchannel produced had a clean edge indicating good master mold was produced using the cutting plotter and the bonding between the PDMS and glass was good where no leakage was observed. The materials used in this method is cheap and the total time consumed is less than 5 hours where this method is suitable for rapid prototyping of microchannel.