Issues in measure-preserving three dimensional flow integrators: Self-adjointness, reversibility, and non-uniform time stepping

International Nuclear Information System (INIS)

Finn, John M.

2015-01-01

Properties of integration schemes for solenoidal fields in three dimensions are studied, with a focus on integrating magnetic field lines in a plasma using adaptive time stepping. It is shown that implicit midpoint (IM) and a scheme we call three-dimensional leapfrog (LF) can do a good job (in the sense of preserving KAM tori) of integrating fields that are reversible, or (for LF) have a “special divergence-free” (SDF) property. We review the notion of a self-adjoint scheme, showing that such schemes are at least second order accurate and can always be formed by composing an arbitrary scheme with its adjoint. We also review the concept of reversibility, showing that a reversible but not exactly volume-preserving scheme can lead to a fractal invariant measure in a chaotic region, although this property may not often be observable. We also show numerical results indicating that the IM and LF schemes can fail to preserve KAM tori when the reversibility property (and the SDF property for LF) of the field is broken. We discuss extensions to measure preserving flows, the integration of magnetic field lines in a plasma and the integration of rays for several plasma waves. The main new result of this paper relates to non-uniform time stepping for volume-preserving flows. We investigate two potential schemes, both based on the general method of Feng and Shang [Numer. Math. 71, 451 (1995)], in which the flow is integrated in split time steps, each Hamiltonian in two dimensions. The first scheme is an extension of the method of extended phase space, a well-proven method of symplectic integration with non-uniform time steps. This method is found not to work, and an explanation is given. The second method investigated is a method based on transformation to canonical variables for the two split-step Hamiltonian systems. This method, which is related to the method of non-canonical generating functions of Richardson and Finn [Plasma Phys. Controlled Fusion 54, 014004 (2012

On the Derivation of Highest-Order Compact Finite Difference Schemes for the One- and Two-Dimensional Poisson Equation with Dirichlet Boundary Conditions

KAUST Repository

Settle, Sean O.

2013-01-01

The primary aim of this paper is to answer the question, What are the highest-order five- or nine-point compact finite difference schemes? To answer this question, we present several simple derivations of finite difference schemes for the one- and two-dimensional Poisson equation on uniform, quasi-uniform, and nonuniform face-to-face hyperrectangular grids and directly prove the existence or nonexistence of their highest-order local accuracies. Our derivations are unique in that we do not make any initial assumptions on stencil symmetries or weights. For the one-dimensional problem, the derivation using the three-point stencil on both uniform and nonuniform grids yields a scheme with arbitrarily high-order local accuracy. However, for the two-dimensional problem, the derivation using the corresponding five-point stencil on uniform and quasi-uniform grids yields a scheme with at most second-order local accuracy, and on nonuniform grids yields at most first-order local accuracy. When expanding the five-point stencil to the nine-point stencil, the derivation using the nine-point stencil on uniform grids yields at most sixth-order local accuracy, but on quasi- and nonuniform grids yields at most fourth- and third-order local accuracy, respectively. © 2013 Society for Industrial and Applied Mathematics.

Pumping tests in nonuniform aquifers - The radially symmetric case

Science.gov (United States)

Butler, J.J.

1988-01-01

Traditionally, pumping-test-analysis methodology has been limited to applications involving aquifers whose properties are assumed uniform in space. This work attempts to assess the applicability of analytical methodology to a broader class of units with spatially varying properties. An examination of flow behavior in a simple configuration consisting of pumping from the center of a circular disk embedded in a matrix of differing properties is the basis for this investigation. A solution describing flow in this configuration is obtained through Laplace-transform techniques using analytical and numerical inversion schemes. Approaches for the calculation of flow properties in conditions that can be roughly represented by this simple configuration are proposed. Possible applications include a wide variety of geologic structures, as well as the case of a well skin resulting from drilling or development. Of more importance than the specifics of these techniques for analysis of water-level responses is the insight into flow behavior during a pumping test that is provided by the large-time form of the derived solution. The solution reveals that drawdown during a pumping test can be considered to consist of two components that are dependent and independent of near-well properties, respectively. Such an interpretation of pumping-test drawdown allows some general conclusions to be drawn concerning the relationship between parameters calculated using analytical approaches based on curve-matching and those calculated using approaches based on the slope of a semilog straight line plot. The infinite-series truncation that underlies the semilog analytical approaches is shown to remove further contributions of near-well material to total drawdown. In addition, the semilog distance-drawdown approach is shown to yield an expression that is equivalent to the Thiem equation. These results allow some general recommendations to be made concerning observation-well placement for pumping

POSSOL, 2-D Poisson Equation Solver for Nonuniform Grid

International Nuclear Information System (INIS)

Orvis, W.J.

1988-01-01

1 - Description of program or function: POSSOL is a two-dimensional Poisson equation solver for problems with arbitrary non-uniform gridding in Cartesian coordinates. It is an adaptation of the uniform grid PWSCRT routine developed by Schwarztrauber and Sweet at the National Center for Atmospheric Research (NCAR). 2 - Method of solution: POSSOL will solve the Helmholtz equation on an arbitrary, non-uniform grid on a rectangular domain allowing only one type of boundary condition on any one side. It can also be used to handle more than one type of boundary condition on a side by means of a capacitance matrix technique. There are three types of boundary conditions that can be applied: fixed, derivative, or periodic

Adaptive Image Transmission Scheme over Wavelet-Based OFDM System

Institute of Scientific and Technical Information of China (English)

GAOXinying; YUANDongfeng; ZHANGHaixia

2005-01-01

In this paper an adaptive image transmission scheme is proposed over Wavelet-based OFDM (WOFDM) system with Unequal error protection (UEP) by the design of non-uniform signal constellation in MLC. Two different data division schemes: byte-based and bitbased, are analyzed and compared. Different bits are protected unequally according to their different contribution to the image quality in bit-based data division scheme, which causes UEP combined with this scheme more powerful than that with byte-based scheme. Simulation results demonstrate that image transmission by UEP with bit-based data division scheme presents much higher PSNR values and surprisingly better image quality. Furthermore, by considering the tradeoff of complexity and BER performance, Haar wavelet with the shortest compactly supported filter length is the most suitable one among orthogonal Daubechies wavelet series in our proposed system.

Gas-Dynamic Methods to Reduce Gas Flow Nonuniformity from the Annular Frames of Gas Turbine Engines

Science.gov (United States)

Kolmakova, D.; Popov, G.

2018-01-01

Gas flow nonuniformity is one of the main sources of rotor blade vibrations in the gas turbine engines. Usually, the flow circumferential nonuniformity occurs near the annular frames, located in the flow channel of the engine. This leads to the increased dynamic stresses in blades and consequently to the blade damage. The goal of the research was to find an acceptable method of reducing the level of gas flow nonuniformity. Two different methods were investigated during this research. Thus, this study gives the ideas about methods of improving the flow structure in gas turbine engine. Based on existing conditions (under development or existing engine) it allows the selection of the most suitable method for reducing gas flow nonuniformity.

Reduction of gas flow nonuniformity in gas turbine engines by means of gas-dynamic methods

Science.gov (United States)

Matveev, V.; Baturin, O.; Kolmakova, D.; Popov, G.

2017-08-01

Gas flow nonuniformity is one of the main sources of rotor blade vibrations in the gas turbine engines. Usually, the flow circumferential nonuniformity occurs near the annular frames, located in the flow channel of the engine. This leads to the increased dynamic stresses in blades and as a consequence to the blade damage. The goal of the research was to find an acceptable method of reducing the level of gas flow nonuniformity as the source of dynamic stresses in the rotor blades. Two different methods were investigated during this research. Thus, this study gives the ideas about methods of improving the flow structure in gas turbine engine. On the basis of existing conditions (under development or existing engine) it allows the selection of the most suitable method for reducing gas flow nonuniformity.

Non-uniformity measurements of PbWO4 crystals

International Nuclear Information System (INIS)

Depasse, P.; Ernenwein, J.P.; Ille, B.; Martin, F.; Rosset, C.; Zach, F.

1998-11-01

Two independent methods have been used to measure the longitudinal non-uniformity scintillation response of 3 different (23-cm long) PbWO 4 crystals. The first one is the classical 60 Co source method. The source is collimated along the crystal, each 1,5-cm, and the scintillation signal is measured with a photomultiplier (a hybrid photomultiplier in our case). The second one is the use of cosmic particles (Minimum Ionizing Particles). A cosmic bench allows reconstructing the track of the MIP's and thus the energy deposit with the help of a full GEANT simulation of the setup. Variations of E along the crystal artificially cut in 1,5-cm divisions, leads to determine the non-uniformity. The conclusion is that both methods agree quite well. Furthermore, a good estimation of crystal light yield can be obtained. (author)

Non-similar solutions for unsteady flow over a yawed cylinder with non-uniform mass transfer through a slot

Directory of Open Access Journals (Sweden)

G. Revathi

2014-12-01

Full Text Available Non-similar solutions are found numerically to a system of coupled non-linear partial differential equations indicating, unsteady laminar water boundary layer flow over yawed cylinder using implicit finite difference scheme along with Quasi-linearization technique. The fluid properties such as viscosity and Prandtl number are considered as an inverse function of temperature. Unsteadiness is caused by upstream velocity in and directions and non-uniform mass transfer (suction/injection which is applied through slot on the surface of the geometry. The effect of yaw angle, variable fluid properties and non-uniform mass transfer on skin friction and heat transfer coefficients is analyzed. It is found that non-uniform slot suction and downstream movement of the slot cause the point of vanishing skin friction moves downstream, but non-uniform slot injection produces the opposite result of that corresponding to the suction case. When the yaw angle increases, both the skin friction coefficient in the – direction and the heat transfer coefficient decrease but the skin friction coefficient in the – direction increases for all times. The effect of the yaw angle is very little on the point of vanishing skin friction.

Instruction sequence based non-uniform complexity classes

NARCIS (Netherlands)

Bergstra, J.A.; Middelburg, C.A.

2013-01-01

We present an approach to non-uniform complexity in which single-pass instruction sequences play a key part, and answer various questions that arise from this approach. We introduce several kinds of non-uniform complexity classes. One kind includes a counterpart of the well-known non-uniform

TDM/FM/FDMA - A modulation technique for multiple-beam satellites which precludes cochannel interference and allows non-uniform geographic distribution of user channels

Science.gov (United States)

Springett, J. C.

1982-01-01

The technique outlined in this paper is intended to eliminate the problems of cochannel interference and uniform geographic distribution of user channels which arise in conventional designs for a multiple spot beam communication satellite to serve mobile telephony users across the CONUS. By time multiplexing FM/FDMA signal ensembles so that only those beams operating on distinct frequency subbands are allowed to transmit concurrently, cochannel interference arising from simultaneous frequency subband reuse is precluded. Thus, time disjoint frequency reuse is accomplished over a repetitive sequence of fixed time slots. By assigning different size subbands to each time slot, a market of nonuniform users can be accommodated. The technique results in a greatly simplified antenna feed system design for the satellite, at a cost of imposing the need for time slot synchronization on the mobile FM receivers whose ability for rejecting adjacent channel interference is somewhat diminished.

TDM/FM/FDMA - A modulation technique for multiple-beam satellites which precludes cochannel interference and allows non-uniform geographic distribution of user channels

Science.gov (United States)

Springett, J. C.

The technique outlined in this paper is intended to eliminate the problems of cochannel interference and uniform geographic distribution of user channels which arise in conventional designs for a multiple spot beam communication satellite to serve mobile telephony users across the CONUS. By time multiplexing FM/FDMA signal ensembles so that only those beams operating on distinct frequency subbands are allowed to transmit concurrently, cochannel interference arising from simultaneous frequency subband reuse is precluded. Thus, time disjoint frequency reuse is accomplished over a repetitive sequence of fixed time slots. By assigning different size subbands to each time slot, a market of nonuniform users can be accommodated. The technique results in a greatly simplified antenna feed system design for the satellite, at a cost of imposing the need for time slot synchronization on the mobile FM receivers whose ability for rejecting adjacent channel interference is somewhat diminished.

Quantum ratchet effect in a time non-uniform double-kicked model

Science.gov (United States)

Chen, Lei; Wang, Zhen-Yu; Hui, Wu; Chu, Cheng-Yu; Chai, Ji-Min; Xiao, Jin; Zhao, Yu; Ma, Jin-Xiang

2017-07-01

The quantum ratchet effect means that the directed transport emerges in a quantum system without a net force. The delta-kicked model is a quantum Hamiltonian model for the quantum ratchet effect. This paper investigates the quantum ratchet effect based on a time non-uniform double-kicked model, in which two flashing potentials alternately act on a particle with a homogeneous initial state of zero momentum, while the intervals between adjacent actions are not equal. The evolution equation of the state of the particle is derived from its Schrödinger equation, and the numerical method to solve the evolution equation is pointed out. The results show that quantum resonances can induce the ratchet effect in this time non-uniform double-kicked model under certain conditions; some quantum resonances, which cannot induce the ratchet effect in previous models, can induce the ratchet effect in this model, and the strengths of the ratchet effect in this model are stronger than those in previous models under certain conditions. These results enrich people’s understanding of the delta-kicked model, and provides a new optional scheme to control the quantum transport of cold atoms in experiment.

Assessment of 12 CHF prediction methods, for an axially non-uniform heat flux distribution, with the RELAP5 computer code

Energy Technology Data Exchange (ETDEWEB)

Ferrouk, M. [Laboratoire du Genie Physique des Hydrocarbures, University of Boumerdes, Boumerdes 35000 (Algeria)], E-mail: m_ferrouk@yahoo.fr; Aissani, S. [Laboratoire du Genie Physique des Hydrocarbures, University of Boumerdes, Boumerdes 35000 (Algeria); D' Auria, F.; DelNevo, A.; Salah, A. Bousbia [Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione, Universita di Pisa (Italy)

2008-10-15

The present article covers the evaluation of the performance of twelve critical heat flux methods/correlations published in the open literature. The study concerns the simulation of an axially non-uniform heat flux distribution with the RELAP5 computer code in a single boiling water reactor channel benchmark problem. The nodalization scheme employed for the considered particular geometry, as modelled in RELAP5 code, is described. For this purpose a review of critical heat flux models/correlations applicable to non-uniform axial heat profile is provided. Simulation results using the RELAP5 code and those obtained from our computer program, based on three type predictions methods such as local conditions, F-factor and boiling length average approaches were compared.

Going from microscopic to macroscopic on nonuniform growing domains.

Science.gov (United States)

Yates, Christian A; Baker, Ruth E; Erban, Radek; Maini, Philip K

2012-08-01

Throughout development, chemical cues are employed to guide the functional specification of underlying tissues while the spatiotemporal distributions of such chemicals can be influenced by the growth of the tissue itself. These chemicals, termed morphogens, are often modeled using partial differential equations (PDEs). The connection between discrete stochastic and deterministic continuum models of particle migration on growing domains was elucidated by Baker, Yates, and Erban [Bull. Math. Biol. 72, 719 (2010)] in which the migration of individual particles was modeled as an on-lattice position-jump process. We build on this work by incorporating a more physically reasonable description of domain growth. Instead of allowing underlying lattice elements to instantaneously double in size and divide, we allow incremental element growth and splitting upon reaching a predefined threshold size. Such a description of domain growth necessitates a nonuniform partition of the domain. We first demonstrate that an individual-based stochastic model for particle diffusion on such a nonuniform domain partition is equivalent to a PDE model of the same phenomenon on a nongrowing domain, providing the transition rates (which we derive) are chosen correctly and we partition the domain in the correct manner. We extend this analysis to the case where the domain is allowed to change in size, altering the transition rates as necessary. Through application of the master equation formalism we derive a PDE for particle density on this growing domain and corroborate our findings with numerical simulations.

Compensation for nonuniform attenuation in SPECT brain imaging

International Nuclear Information System (INIS)

Glick, S.J.; King, M.A.; Pan, T.S.; Soares, E.J.

1996-01-01

Accurate compensation for photon attenuation is needed to perform quantitative brain single-photon-emission computed tomographic (SPECT) imaging. Bellini's attenuation-compensation method has been used with a nonuniform attenuation map to account for the nonuniform attenuation properties of the head. Simulation studies using a three-dimensional (3-D) digitized anthropomorphic brain phantom were conducted to compare quantitative accuracy of reconstructions obtained with the nonuniform Bellini method to that obtained with the Chang method and to iterative reconstruction using maximum-likelihood expectation maximization (ML-EM). Using the Chang method and assuming the head to be a uniform attenuator gave reconstructions with an average bias of approximately 6-8%, whereas using the Bellini or the iterative ML-EM method with a nonuniform attenuation map gave an average bias of approximately 1%. The computation time required to implement nonuniform attenuation compensation with the Bellini algorithm is approximately equivalent to the time required to perform one iteration of ML-EM. Thus, using the Bellini method with a nonuniform attenuation map provides accurate compensation for photon attenuation within the head, and the method can be implemented in computation times suitable for routine clinical use

Estimation of Interchannel Time Difference in Frequency Subbands Based on Nonuniform Discrete Fourier Transform

Directory of Open Access Journals (Sweden)

Qiu Bo

2008-01-01

Full Text Available Binaural cue coding (BCC is an efficient technique for spatial audio rendering by using the side information such as interchannel level difference (ICLD, interchannel time difference (ICTD, and interchannel correlation (ICC. Of the side information, the ICTD plays an important role to the auditory spatial image. However, inaccurate estimation of the ICTD may lead to the audio quality degradation. In this paper, we develop a novel ICTD estimation algorithm based on the nonuniform discrete Fourier transform (NDFT and integrate it with the BCC approach to improve the decoded auditory image. Furthermore, a new subjective assessment method is proposed for the evaluation of auditory image widths of decoded signals. The test results demonstrate that the NDFT-based scheme can achieve much wider and more externalized auditory image than the existing BCC scheme based on the discrete Fourier transform (DFT. It is found that the present technique, regardless of the image width, does not deteriorate the sound quality at the decoder compared to the traditional scheme without ICTD estimation.

Non-uniform sampling of NMR relaxation data

DEFF Research Database (Denmark)

Schwarz-Linnet, Troels; Teilum, Kaare

2016-01-01

The use of non-uniform sampling of NMR spectra may give significant reductions in the data acquisition time. For quantitative experiments such as the measurement of spin relaxation rates, non-uniform sampling is however not widely used as inaccuracies in peak intensities may lead to errors...... in the extracted dynamic parameters. By systematic reducing the coverage of the Nyquist grid of (15)N Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion datasets for four different proteins and performing a full data analysis of the resulting non-uniform sampled datasets, we have compared the performance...... of the multi-dimensional decomposition and iterative re-weighted least-squares algorithms in reconstructing spectra with accurate peak intensities. As long as a single fully sampled spectrum is included in a series of otherwise non-uniform sampled two-dimensional spectra, multi-dimensional decomposition...

Detection of Uniform and Nonuniform Differential Item Functioning by Item-Focused Trees

Science.gov (United States)

Berger, Moritz; Tutz, Gerhard

2016-01-01

Detection of differential item functioning (DIF) by use of the logistic modeling approach has a long tradition. One big advantage of the approach is that it can be used to investigate nonuniform (NUDIF) as well as uniform DIF (UDIF). The classical approach allows one to detect DIF by distinguishing between multiple groups. We propose an…

Interest of seeing Precision Viticulture through two distributed competences: Determination of resources and schemes allowing some practical recommendations

OpenAIRE

Moreiro Leslie B.

2017-01-01

The aim of this article is to better understand resources needed and constraints to avoid in implementation of Precision Viticulture technologies. In this view, we adapt distributed cognition theory to multilevel model of competence in management sciences. We use a qualitative methodology based on semi-structured interviews in 7 cases study. The main results allow us to distinguish the two aspects of Precision Viticulture, artifacts, providers of resources, and their utilization scheme. Furth...

Poverty reduction in Bangladesh: A qualitative analysis of the "Allowance Scheme for Widowed and Husband-deserted Distressed Women"

OpenAIRE

Islam, K.M. Kabirul

2007-01-01

Mastergradsoppgave i "Comparative social work" - Høgskolen i Bodø, 2007 While Bangladesh has been persistently trying to overcome the poverty regime, yet most of the distressed widowed, divorced and husband-deserted women are struggling hard to subsist due to impoverished economic condition. The Government of Bangladesh has given due attention in the recent past to empower these disadvantaged groups of people. The “Allowance Scheme for Widowed and Husband-deserted Distressed Wo...

Properties of multilayer nonuniform holographic structures

International Nuclear Information System (INIS)

Pen, E F; Rodionov, Mikhail Yu

2010-01-01

Experimental results and analysis of properties of multilayer nonuniform holographic structures formed in photopolymer materials are presented. The theoretical hypotheses is proved that the characteristics of angular selectivity for the considered structures have a set of local maxima, whose number and width are determined by the thicknesses of intermediate layers and deep holograms and that the envelope of the maxima coincides with the selectivity contour of a single holographic array. It is also experimentally shown that hologram nonuniformities substantially distort shapes of selectivity characteristics: they become asymmetric, the local maxima differ in size and the depths of local minima reduce. The modelling results are made similar to experimental data by appropriately choosing the nonuniformity parameters. (imaging and image processing. holography)

Cap and trade schemes on waste management: A case study of the Landfill Allowance Trading Scheme (LATS) in England

International Nuclear Information System (INIS)

Calaf-Forn, Maria; Roca, Jordi; Puig-Ventosa, Ignasi

2014-01-01

Highlights: • LATS has been effective to achieve a reduction of the amount of landfilled waste. • LATS has been one of the few environmental instruments for waste management with a cap and trade methodology. • LATS has achieved to increase recycling of the biodegradable and other waste fractions. - Abstract: The Landfill Allowance Trading Scheme (LATS) is one of the main instruments used in England to enforce the landfill diversion targets established in the Directive 1999/31/EC of the European Parliament and of the Council of 26 April 1999 on the landfill of waste (Landfill Directive). Through the LATS, biodegradable municipal waste (BMW) allowances for landfilling are allocated to each local authority, otherwise known as waste disposal authorities (WDAs). The quantity of landfill allowances received is expected to decrease continuously from 2005/06 to 2019/20 so as to meet the objectives of the Landfill Directive. To achieve their commitments, WDAs can exchange, buy, sell or transfer allowances among each other, or may re-profile their own allocation through banking and/or borrowing. Despite the goals for the first seven years – which included two target years (2005/06 and 2009/10) – being widely achieved (the average allocation of allowances per WDA was 22.9% higher than those finally used), market activity among WDAs was high and prices were not very stable. Results in terms of waste reduction and recycling levels have been satisfactory. The reduction of BMW landfilled (in percentage) was higher during the first seven years of the LATS period (2005/06–2011/12) (around 7% annually) than during the previous period (2001/02–2004/05) (4.2% annually). Since 2008, the significance of the LATS diminished because of an increase in the rate of the UK Landfill Tax. The LATS was suppressed after the 2012/13 target year, before what it was initially scheduled. The purpose of this paper is to describe the particularities of the LATS, analyse its performance as

Cap and trade schemes on waste management: A case study of the Landfill Allowance Trading Scheme (LATS) in England

Energy Technology Data Exchange (ETDEWEB)

Calaf-Forn, Maria, E-mail: mcalaf@ent.cat [Institut de Ciència i Tecnologia Ambientals (ICTA), Universitat Autònoma de Barcelona (UAB), E-08193 Bellaterra, Barcelona (Spain); ENT Environment and Management, Carrer Sant Joan 39, First Floor, E-08800 Vilanova i la Geltrú, Barcelona (Spain); Roca, Jordi [Departament de Teoria Econòmica, Universitat de Barcelona (UB), Diagonal, 696, E-08034 Barcelona (Spain); Puig-Ventosa, Ignasi [ENT Environment and Management, Carrer Sant Joan 39, First Floor, E-08800 Vilanova i la Geltrú, Barcelona (Spain)

2014-05-01

Highlights: • LATS has been effective to achieve a reduction of the amount of landfilled waste. • LATS has been one of the few environmental instruments for waste management with a cap and trade methodology. • LATS has achieved to increase recycling of the biodegradable and other waste fractions. - Abstract: The Landfill Allowance Trading Scheme (LATS) is one of the main instruments used in England to enforce the landfill diversion targets established in the Directive 1999/31/EC of the European Parliament and of the Council of 26 April 1999 on the landfill of waste (Landfill Directive). Through the LATS, biodegradable municipal waste (BMW) allowances for landfilling are allocated to each local authority, otherwise known as waste disposal authorities (WDAs). The quantity of landfill allowances received is expected to decrease continuously from 2005/06 to 2019/20 so as to meet the objectives of the Landfill Directive. To achieve their commitments, WDAs can exchange, buy, sell or transfer allowances among each other, or may re-profile their own allocation through banking and/or borrowing. Despite the goals for the first seven years – which included two target years (2005/06 and 2009/10) – being widely achieved (the average allocation of allowances per WDA was 22.9% higher than those finally used), market activity among WDAs was high and prices were not very stable. Results in terms of waste reduction and recycling levels have been satisfactory. The reduction of BMW landfilled (in percentage) was higher during the first seven years of the LATS period (2005/06–2011/12) (around 7% annually) than during the previous period (2001/02–2004/05) (4.2% annually). Since 2008, the significance of the LATS diminished because of an increase in the rate of the UK Landfill Tax. The LATS was suppressed after the 2012/13 target year, before what it was initially scheduled. The purpose of this paper is to describe the particularities of the LATS, analyse its performance as

A Non-Equilibrium Sediment Transport Model for Dam Break Flow over Moveable Bed Based on Non-Uniform Rectangular Mesh

Directory of Open Access Journals (Sweden)

Gangfeng Wu

2018-05-01

Full Text Available The use of multiple-level non-uniform rectangular mesh in coupled flow and sediment transport modeling is preferred to achieve high accuracy in important region without increasing computational cost greatly. Here, a robust coupled hydrodynamic and non-equilibrium sediment transport model is developed on non-uniform rectangular mesh to simulate dam break flow over movable beds. The enhanced shallow water and sediment transport equations are adopted to consider the mass and momentum exchange between the flow phase and sediment phase. The flux at the interface is calculated by the positivity preserving central upwind scheme, which belongs to Godunov-type Riemann-problem-solver-free central schemes and is less expensive than other popular Riemann solvers while still capable of tracking wet/dry fronts accurately. The nonnegative water depth reconstruction method is used to achieve second-order accuracy in space. The model was first verified against two laboratory experiments of dam break flow over irregular fixed bed. Then the quantitative performance of the model was further investigated by comparing the computational results with measurement data of dam break flow over movable bed. The good agreements between the measurements and the numerical simulations are found for the flow depth, velocity and bed changes.

A stability criterion for HNFDE with non-uniform delays

International Nuclear Information System (INIS)

Liu Xingwen; Zhong Shouming; Zhang Fengli

2005-01-01

Stability of functional differential equations (FDE) is an increasingly important problem in both science and engineering. Delays, whether uniform or non-uniform, play an important role in the dynamics of a system. Since non-uniform delay is more general and less focused than uniform delay, this paper concentrates on the stability of high-order neutral functional differential equations (HNFDE) with non-uniform delay, and proposes a sufficient condition for it. This result may be widely helpful, thanks to the frequent emergence of a HNFDE with non-uniform delay in various fields. Its effectiveness is illustrated by some examples

Quasiparticles in non-uniformly magnetized plasma

International Nuclear Information System (INIS)

Sosenko, P.P.

1994-01-01

A quasiparticle concept is generalized for the case of non-uniformly magnetized plasma. Exact and reduced continuity equations for the microscopic density in the quasiparticle phase space are derived, and the nature of quasiparticles is analyzed. The theory is developed for the general case of relativistic particles in electromagnetic fields, besides non-uniform but stationary magnetic fields. Effects of non-stationary magnetic fields are briefly investigated also. 26 refs

Statistical evaluation of unobserved nonuniform corrosion in A216 steel

International Nuclear Information System (INIS)

Pulsipher, B.A.

1988-07-01

Tests designed to promote nonuniform corrosion have been conducted at PNL on A216 steel. In all of the tests performed to date, there have been no manifestations of significant nonuniform corrosion. Although this may suggest that nonuniform corrosion in A216 steel may not be a significant problem in the nuclear waste repository, a question arises as to whether enough tests have been conducted for a sufficient length of time to rule out nonuniform corrosion of A216 steel. In this report, a method for determining the required number of tests is examined for two of the mechanisms of nonuniform corrosion: pitting and crevice corrosion

Conductance dips and spin precession in a nonuniform waveguide with spin–orbit coupling

Energy Technology Data Exchange (ETDEWEB)

Malyshev, A. I., E-mail: malyshev@phys.unn.ru; Kozulin, A. S. [Lobachevsky Nizhny Novgorod State University (Russian Federation)

2015-07-15

An infinite waveguide with a nonuniformity, a segment of finite length with spin–orbit coupling, is considered in the case when the Rashba and Dresselhaus parameters are identical. Analytical expressions have been derived in the single-mode approximation for the conductance of the system for an arbitrary initial spin state. Based on numerical calculations with several size quantization modes, we have detected and described the conductance dips arising when the waves are localized in the nonuniformity due to the formation of an effective potential well in it. We show that allowance for the evanescent modes under carrier spin precession in an effective magnetic field does not lead to a change in the direction of the average spin vector at the output of the system.

Stable and efficient retrospective 4D-MRI using non-uniformly distributed quasi-random numbers

Science.gov (United States)

Breuer, Kathrin; Meyer, Cord B.; Breuer, Felix A.; Richter, Anne; Exner, Florian; Weng, Andreas M.; Ströhle, Serge; Polat, Bülent; Jakob, Peter M.; Sauer, Otto A.; Flentje, Michael; Weick, Stefan

2018-04-01

The purpose of this work is the development of a robust and reliable three-dimensional (3D) Cartesian imaging technique for fast and flexible retrospective 4D abdominal MRI during free breathing. To this end, a non-uniform quasi random (NU-QR) reordering of the phase encoding (k y –k z ) lines was incorporated into 3D Cartesian acquisition. The proposed sampling scheme allocates more phase encoding points near the k-space origin while reducing the sampling density in the outer part of the k-space. Respiratory self-gating in combination with SPIRiT-reconstruction is used for the reconstruction of abdominal data sets in different respiratory phases (4D-MRI). Six volunteers and three patients were examined at 1.5 T during free breathing. Additionally, data sets with conventional two-dimensional (2D) linear and 2D quasi random phase encoding order were acquired for the volunteers for comparison. A quantitative evaluation of image quality versus scan times (from 70 s to 626 s) for the given sampling schemes was obtained by calculating the normalized mutual information (NMI) for all volunteers. Motion estimation was accomplished by calculating the maximum derivative of a signal intensity profile of a transition (e.g. tumor or diaphragm). The 2D non-uniform quasi-random distribution of phase encoding lines in Cartesian 3D MRI yields more efficient undersampling patterns for parallel imaging compared to conventional uniform quasi-random and linear sampling. Median NMI values of NU-QR sampling are the highest for all scan times. Therefore, within the same scan time 4D imaging could be performed with improved image quality. The proposed method allows for the reconstruction of motion artifact reduced 4D data sets with isotropic spatial resolution of 2.1  ×  2.1  ×  2.1 mm3 in a short scan time, e.g. 10 respiratory phases in only 3 min. Cranio-caudal tumor displacements between 23 and 46 mm could be observed. NU-QR sampling enables for stable 4D

Theoretical investigations on two-phase flow instability in parallel channels under axial non-uniform heating

International Nuclear Information System (INIS)

Lu, Xiaodong; Wu, Yingwei; Zhou, Linglan; Tian, Wenxi; Su, Guanghui; Qiu, Suizheng; Zhang, Hong

2014-01-01

Highlights: • We developed a model based on homogeneous flow model to analyze two-phase flow instability in parallel channels. • The influence of axial non-uniform heating on the system stability has been investigated. • Influences of various factors on system instability under cosine heat flux have been studied. • The system under top-peaked heat flux is the most stable system. - Abstract: Two-phase flow instability in parallel channels heated by axial non-uniform heat flux has been theoretically studied in this paper. The system control equations of parallel channels were established based on the homogeneous flow model in two-phase region. Semi-implicit finite-difference scheme and staggered mesh method were used to discretize the equations, and the difference equations were solved by chasing method. Cosine, bottom-peaked and top-peaked heat fluxes were used to study the influence of non-uniform heating on two-phase flow instability of the parallel channels system. The marginal stability boundaries (MSB) of parallel channels and three-dimensional instability spaces (or instability reefs) under different heat flux conditions have been obtained. Compared with axial uniform heating, axial non-uniform heating will affect the system stability. Cosine and bottom-peaked heat fluxes can destabilize the system stability in high inlet subcooling region, while the opposite effect can be found in low inlet subcooling region. However, top-peaked heat flux can enhance the system stability in the whole region. In addition, for cosine heat flux, increasing the system pressure or inlet resistance coefficient can strengthen the system stability, and increasing the heating power will destabilize the system stability. The influence of inlet subcooling number on the system stability is multi-valued under cosine heat flux

Induced charge of spherical dust particle on plasma-facing wall in non-uniform electric field

International Nuclear Information System (INIS)

Tomita, Y.; Smirnov, R.; Zhu, S.

2005-01-01

Induced charge of a spherical dust particle on a plasma-facing wall is investigated analytically, where non-uniform electric field is applied externally. The one-dimensional non-uniform electrostatic potential is approximated by the polynomial of the normal coordinate toward the wall. The bipolar coordinate is introduced to solve the Laplace equation of the induced electrostatic potential. The boundary condition at the dust surface determines the unknown coefficients of the general solution of the Laplace equation for the induced potential. From the obtained potential the surface induced charge can be calculated. This result allows estimating the effect of the surrounding plasma, which shields the induced charge. (author)

Nonuniformity mitigation of beam illumination in heavy ion inertial fusion

International Nuclear Information System (INIS)

Kawata, S; Noguchi, K; Suzuki, T; Kurosaki, T; Barada, D; Ogoyski, A I; Zhang, W; Xie, J; Zhang, H; Dai, D

2014-01-01

In inertial fusion, a target DT fuel should be compressed to typically 1000 times the solid density. The target implosion nonuniformity is introduced by a driver beam’s illumination nonuniformity, for example. The target implosion should be robust against the implosion nonuniformities. In this paper, the requirement for implosion uniformity is first discussed. The implosion non-uniformity should be less than a few percent. The implosion dynamics is also briefly reviewed in heavy ion inertial fusion (HIF). Heavy ions deposit their energy inside the target energy absorber, and the energy deposition layer is rather thick, depending on the ion particle energy. Then nonuniformity mitigation mechanisms of the heavy ion beam (HIB) illumination in HIF are discussed. A density valley appears in the energy absorber, and the large-scale density valley also works as a radiation energy confinement layer, which contributes to a radiation energy smoothing. In HIF, wobbling heavy ion beam illumination was also introduced to realize a uniform implosion. The wobbling HIB axis oscillation is precisely controlled. In the wobbling HIBs’ illumination, the illumination nonuniformity oscillates in time and space on an HIF target. The oscillating-HIB energy deposition may contribute to the reduction of the HIBs’ illumination nonuniformity by its smoothing effect on the HIB illumination nonuniformity and also by a growth mitigation effect on the Rayleigh–Taylor instability. (invited comment)

A non-uniform expansion mechanical safety model of the stent.

Science.gov (United States)

Yang, J; Huang, N; Du, Q

2009-01-01

Stents have a serial unstable structure that readily leads to non-uniform expansion. Non-uniform expansion in turn creates a stent safety problem. We explain how a stent may be simplified to a serial unstable structure, and present a method to calculate the non-uniform expansion of the stent on the basis of the serial unstable structure. We propose a safety criterion based on the expansion displacement instead of the strain, and explain that the parameter Rd, the ratio of the maximum displacement of the elements to normal displacement, is meaningful to assess the safety level of the stent. We also examine how laser cutting influences non-uniform expansion. The examples illustrate how to calculate the parameter Rd to assess non-uniform expansion of the stent, and demonstrate how the laser cutting offset and strengthening coefficient of the material influence the stent expansion behaviour. The methods are valuable for assessing stent safety due to non-uniform expansion.

Integer channels in nonuniform non-equilibrium 2D systems

Science.gov (United States)

Shikin, V.

2018-01-01

We discuss the non-equilibrium properties of integer channels in nonuniform 2D electron (hole) systems in the presence of a strong magnetic field. The results are applied to a qualitative explanation of the Corbino disk current-voltage characteristics (IVC) in the quantum Hall effect (QHE) regime. Special consideration is paid to the so-called "QHE breakdown" effect, which is readily observed in both the Hall bar and Corbino geometries of the tested cells. The QHE breakdown is especially evident in the Corbino samples, allowing for a more in-depth study of these effects.

Carbon allowance auction design of China's emissions trading scheme: A multi-agent-based approach

International Nuclear Information System (INIS)

Tang, Ling; Wu, Jiaqian; Yu, Lean; Bao, Qin

2017-01-01

In this paper, a multi-agent-based ETS simulation model is proposed for carbon allowance auction design in China. In the proposed model, two main agents, i.e., the government (the ETS implementer) and the firms in different sectors (the ETS targets), are considered. Under the ETS policy, all agents make various decisions individually according to their own goals, and interact with each other through three main markets: the commodity market, the primary carbon auction market and the secondary carbon trading market. Different popular auction designs are introduced into the ETS formulation to offer helpful insights into China's ETS design. (1) Generally, the ETS would lead to positive effects on China's carbon mitigation and energy structure improvement, but a negative impact on economy. (2) As for auction forms, the uniform-price design is relatively moderate, while the discriminative-price design is quite aggressive in both economic damage and emissions reduction. (3) As for carbon price, the uniform-price auction might generate a slightly higher market clearing price than the discriminative-price auction, and the prices under two auction rules fluctuate about RMB 40 per metric ton. (4) As for carbon cap, the total allowances in the carbon auction market should be carefully set to well balance economic growth and mitigation effect. - Highlights: • A multi-agent-based model is proposed for China's emissions trading scheme (ETS). • Two main economic agents are included: government and firms in different sectors. • Auction-based allocation for initial carbon allowances is especially investigated. • Economic and environmental impacts of different auction designs are analyzed. • Results confirm the validity of the model and give helpful insights into ETS design.

Alternative methods for evaluation of non-uniformity in nuclear medicine images

International Nuclear Information System (INIS)

Rasaneh, S.; Rajabi, H.; Hajizadeh, E.

2005-01-01

Non-uniformity test is the most essential in daily quality control procedures of nuclear medicine equipment's. However, the calculation of non-uniformity is hindered due to high level of noise in nuclear medicine data. Non-uniformity may be considered as a type of systematic error while noise is certainly a random error. The present methods of uniformity evaluation are not able to distinguish between systematic and random error and therefore produce incorrect results when noise is significant. In the present study, two hypothetical methods have been tested for evaluation of non-uniformity in nuclear medicine images. Materials and Methods: Using the Monte Carlo method, uniform and non-uniform flood images of different matrix sizes and different counts were generated. The uniformity of the images was calculated using the conventional method and proposed methods. The results were compared with the known non-uniformity data of simulated images. Results: It was observed that the value of integral uniformity never went below the recommended values except in small matrix size of high counts (more than 80 millions counts). The differential uniformity was quite insensitive to the degree of non-uniformity in large matrix size. Matrix size of 64*64 was only found to be suitable for the calculation of differential uniformity. It was observed that in uniform images, a small amount of non-uniformity changes the p-value of Kolmogorov-Smirnov test and noise amplitude of fast fourier transformation test significantly while the conventional methods failed to detect the nonuniformity. Conclusion: The conventional methods do not distinguish noise, which is always present in the data and occasional non-uniformity at low count density. In a uniform intact flood image, the difference between maximum and minimum pixel count (the value of integral uniformity) is much more than the recommended values for non-uniformity. After filtration of image, this difference decreases, but remains high

Selective exfoliation of single-layer graphene from non-uniform graphene grown on Cu

International Nuclear Information System (INIS)

Lim, Jae-Young; Lee, Jae-Hyun; Jang, Hyeon-Sik; Whang, Dongmok; Joo, Won-Jae; Hwang, SungWoo

2015-01-01

Graphene growth on a copper surface via metal-catalyzed chemical vapor deposition has several advantages in terms of providing high-quality graphene with the potential for scale-up, but the product is usually inhomogeneous due to the inability to control the graphene layer growth. The non-uniform regions strongly affect the reliability of the graphene in practical electronic applications. Herein, we report a novel graphene transfer method that allows for the selective exfoliation of single-layer graphene from non-uniform graphene grown on a Cu foil. Differences in the interlayer bonding energy are exploited to mechanically separate only the top single-layer graphene and transfer this to an arbitrary substrate. The dry-transferred single-layer graphene showed electrical characteristics that were more uniform than those of graphene transferred using conventional wet-etching transfer steps. (paper)

Axisymmetric alternating direction explicit scheme for efficient coupled simulation of hydro-mechanical interaction in geotechnical engineering—Application to circular footing and deep tunnel in saturated ground

Directory of Open Access Journals (Sweden)

Simon Heru Prassetyo

2018-04-01

Full Text Available Explicit solution techniques have been widely used in geotechnical engineering for simulating the coupled hydro-mechanical (H-M interaction of fluid flow and deformation induced by structures built above and under saturated ground, i.e. circular footing and deep tunnel. However, the technique is only conditionally stable and requires small time steps, portending its inefficiency for simulating large-scale H-M problems. To improve its efficiency, the unconditionally stable alternating direction explicit (ADE scheme could be used to solve the flow problem. The standard ADE scheme, however, is only moderately accurate and is restricted to uniform grids and plane strain flow conditions. This paper aims to remove these drawbacks by developing a novel high-order ADE scheme capable of solving flow problems in non-uniform grids and under axisymmetric conditions. The new scheme is derived by performing a fourth-order finite difference (FD approximation to the spatial derivatives of the axisymmetric fluid–diffusion equation in a non-uniform grid configuration. The implicit Crank-Nicolson technique is then applied to the resulting approximation, and the subsequent equation is split into two alternating direction sweeps, giving rise to a new axisymmetric ADE scheme. The pore pressure solutions from the new scheme are then sequentially coupled with an existing geomechanical simulator in the computer code fast Lagrangian analysis of continua (FLAC. This coupling procedure is called the sequentially-explicit coupling technique based on the fourth-order axisymmetric ADE scheme or SEA-4-AXI. Application of SEA-4-AXI for solving axisymmetric consolidation of a circular footing and of advancing tunnel in deep saturated ground shows that SEA-4-AXI reduces computer runtime up to 42%–50% that of FLAC's basic scheme without numerical instability. In addition, it produces high numerical accuracy of the H-M solutions with average percentage difference of only 0.5%�

Non-Uniformity Correction Using Nonlinear Characteristic Performance Curves for Calibration

Science.gov (United States)

Lovejoy, McKenna Roberts

Infrared imaging is an expansive field with many applications. Advances in infrared technology have lead to a greater demand from both commercial and military sectors. However, a known problem with infrared imaging is its non-uniformity. This non-uniformity stems from the fact that each pixel in an infrared focal plane array has its own photoresponse. Many factors such as exposure time, temperature, and amplifier choice affect how the pixels respond to incoming illumination and thus impact image uniformity. To improve performance non-uniformity correction (NUC) techniques are applied. Standard calibration based techniques commonly use a linear model to approximate the nonlinear response. This often leaves unacceptable levels of residual non-uniformity. Calibration techniques often have to be repeated during use to continually correct the image. In this dissertation alternates to linear NUC algorithms are investigated. The goal of this dissertation is to determine and compare nonlinear non-uniformity correction algorithms. Ideally the results will provide better NUC performance resulting in less residual non-uniformity as well as reduce the need for recalibration. This dissertation will consider new approaches to nonlinear NUC such as higher order polynomials and exponentials. More specifically, a new gain equalization algorithm has been developed. The various nonlinear non-uniformity correction algorithms will be compared with common linear non-uniformity correction algorithms. Performance will be compared based on RMS errors, residual non-uniformity, and the impact quantization has on correction. Performance will be improved by identifying and replacing bad pixels prior to correction. Two bad pixel identification and replacement techniques will be investigated and compared. Performance will be presented in the form of simulation results as well as before and after images taken with short wave infrared cameras. The initial results show, using a third order

Optimal threshold of error decision related to non-uniform phase distribution QAM signals generated from MZM based on OCS

Science.gov (United States)

Han, Xifeng; Zhou, Wen

2018-03-01

Optical vector radio-frequency (RF) signal generation based on optical carrier suppression (OCS) in one Mach-Zehnder modulator (MZM) can realize frequency-doubling. In order to match the phase or amplitude of the recovered quadrature amplitude modulation (QAM) signal, phase or amplitude pre-coding is necessary in the transmitter side. The detected QAM signals usually have one non-uniform phase distribution after square-law detection at the photodiode because of the imperfect characteristics of the optical and electrical devices. We propose to use optimal threshold of error decision for non-uniform phase contribution to reduce the bit error rate (BER). By employing this scheme, the BER of 16 Gbaud (32 Gbit/s) quadrature-phase-shift-keying (QPSK) millimeter wave signal at 36 GHz is improved from 1 × 10-3 to 1 × 10-4 at - 4 . 6 dBm input power into the photodiode.

Enceladus's crust as a non-uniform thin shell: I tidal deformations

Science.gov (United States)

Beuthe, Mikael

2018-03-01

The geologic activity at Enceladus's south pole remains unexplained, though tidal deformations are probably the ultimate cause. Recent gravity and libration data indicate that Enceladus's icy crust floats on a global ocean, is rather thin, and has a strongly non-uniform thickness. Tidal effects are enhanced by crustal thinning at the south pole, so that realistic models of tidal tectonics and dissipation should take into account the lateral variations of shell structure. I construct here the theory of non-uniform viscoelastic thin shells, allowing for depth-dependent rheology and large lateral variations of shell thickness and rheology. Coupling to tides yields two 2D linear partial differential equations of the fourth order on the sphere which take into account self-gravity, density stratification below the shell, and core viscoelasticity. If the shell is laterally uniform, the solution agrees with analytical formulas for tidal Love numbers; errors on displacements and stresses are less than 5% and 15%, respectively, if the thickness is less than 10% of the radius. If the shell is non-uniform, the tidal thin shell equations are solved as a system of coupled linear equations in a spherical harmonic basis. Compared to finite element models, thin shell predictions are similar for the deformations due to Enceladus's pressurized ocean, but differ for the tides of Ganymede. If Enceladus's shell is conductive with isostatic thickness variations, surface stresses are approximately inversely proportional to the local shell thickness. The radial tide is only moderately enhanced at the south pole. The combination of crustal thinning and convection below the poles can amplify south polar stresses by a factor of 10, but it cannot explain the apparent time lag between the maximum plume brightness and the opening of tiger stripes. In a second paper, I will study the impact of a non-uniform crust on tidal dissipation.

Nanosecond laser texturing of uniformly and non-uniformly wettable micro structured metal surfaces for enhanced boiling heat transfer

Energy Technology Data Exchange (ETDEWEB)

Zupančič, Matevž, E-mail: matevz.zupancic@fs.uni-lj.si; Može, Matic; Gregorčič, Peter; Golobič, Iztok

2017-03-31

Highlights: • Surfaces with periodically changed wettability were produced by a ns marking laser. • Heat transfer was investigated on uniformly and non-uniformly wettable surfaces. • Microporous surfaces with non-uniform wettability enhance boiling heat transfer. • The most bubble nucleations were observed in the vicinity of the microcavities. • Results agree with the predictions of the nucleation criteria. - Abstract: Microstructured uniformly and non-uniformly wettable surfaces were created on 25-μm-thin stainless steel foils by laser texturing using a marking nanosecond Nd:YAG laser (λ = 1064 nm) and utilizing various laser fluences and scan line separations. High-speed photography and high-speed IR thermography were used to investigate nucleate boiling heat transfer on the microstructured surfaces. The most pronounced results were obtained on a surface with non-uniform microstructure and non-uniform wettability. The obtained results show up to a 110% higher heat transfer coefficients and 20–40 times higher nucleation site densities compared to the untextured surface. We show that the number of active nucleation sites is significantly increased in the vicinity of microcavities that appeared in areas with the smallest (10 μm) scan line separation. Furthermore, this confirms the predictions of nucleation criteria and proves that straightforward, cost-effective nanosecond laser texturing allows the production of cavities with diameters of up to a few micrometers and surfaces with non-uniform wettability. Additionally, this opens up important possibilities for a more deterministic control over the complex boiling process.

Subrandom methods for multidimensional nonuniform sampling.

Science.gov (United States)

Worley, Bradley

2016-08-01

Methods of nonuniform sampling that utilize pseudorandom number sequences to select points from a weighted Nyquist grid are commonplace in biomolecular NMR studies, due to the beneficial incoherence introduced by pseudorandom sampling. However, these methods require the specification of a non-arbitrary seed number in order to initialize a pseudorandom number generator. Because the performance of pseudorandom sampling schedules can substantially vary based on seed number, this can complicate the task of routine data collection. Approaches such as jittered sampling and stochastic gap sampling are effective at reducing random seed dependence of nonuniform sampling schedules, but still require the specification of a seed number. This work formalizes the use of subrandom number sequences in nonuniform sampling as a means of seed-independent sampling, and compares the performance of three subrandom methods to their pseudorandom counterparts using commonly applied schedule performance metrics. Reconstruction results using experimental datasets are also provided to validate claims made using these performance metrics. Copyright © 2016 Elsevier Inc. All rights reserved.

Strategic partitioning of emission allowances under the EU Emission Trading Scheme

Energy Technology Data Exchange (ETDEWEB)

Boehringer, Christoph [Univ. of Oldenburg, Department of Economics, and Centre for European Economic Research (ZEW) (Germany); Rosendahl, Knut Einar [Statistics Norway, Research Department, Pob. 8131 Dep., N-0033 Oslo (Norway)

2009-08-15

The EU Emission Trading Scheme (ETS) is breaking new ground in the experience with emission trading regimes across multiple jurisdictions. Since the EU ETS covers only some industries, it implies a hybrid emission control scheme where EU member states must apply complementary domestic emissions regulation for the non-trading sectors of their economies in order to comply with their national emission reduction targets. The EU ETS thus opens up for strategic partitioning of national emissions budgets by the member states between trading and non-trading sectors. In this paper we examine the potential effects of such strategic behavior on compliance cost and emissions prices. We show that concerns on efficiency losses from strategic partitioning are misplaced. In turn, our analysis implicitly indicates significant political economy forces behind EU climate policy, as both cost-effective and strategically motivated partitioning of national emission budgets are far off from the actual break-down between trading and non-trading sectors. (author)

Pattern of diffusion-limited aggregation on nonuniform substrate

CERN Document Server

Ouyang Wen Ze; Zou Xian Wu; Jin Zhun Zhi

2003-01-01

Pattern of diffusion-limited aggregation (DLA) on nonuniform substrate was investigated by computer simulations. The nonuniform substrates are represented by Leath percolations with the probability p. p stands for the degree of nonuniformity and takes values in the range p sub c<=p<=1, where p sub c is the threshold of percolation. The DLA cluster grows up on the Leath percolation substrate. The patterns of the DLA clusters appear asymmetrical and nonuniform, and the branches are relative few for the case p is close to p sub c. In addition, the pattern depends on the shape of substrate. As p increases from p sub c to 1, cluster changes to pure DLA gradually. Correspondingly, the fractal dimension increases from 1.46 to 1.68. Also, the random walks on Leath percolations through the range p sub c<=p<=1 were examined. Our simulations show the Honda-Toyoki-Matsushita relation is still reasonable for fractional dimensional systems.

CAC DPLB MCN: A Distributed Load Balancing Scheme in Multimedia Mobile Cellular Networks

Directory of Open Access Journals (Sweden)

Sharma Abhijit

2016-11-01

Full Text Available The problem of non-uniform traffic demand in different cells of a cellular network may lead to a gross imbalance in the system performance. Thus, the users in hot cells may suffer from low throughput. In this paper, an effective and simple load balancing scheme CAC_DPLB_MCN is proposed that can effectively reduce the overall call blocking. This model considers dealing with multi-media traffic as well as time-varying geographical traffic distribution. The proposed scheme uses the concept of cell-tiering thereby creating fractional frequency reuse environment. A message exchange based distributed scheme instead of centralized one is used which help the proposed scheme be implemented in a multiple hot cell environment also. Furthermore, concept of dynamic pricing is used to serve the best interest of the users as well as for the service providers. The performance of the proposed scheme is compared with two other existing schemes in terms of call blocking probability and bandwidth utilization. Simulation results show that the proposed scheme can reduce the call blocking significantly in highly congested cell with highest bandwidth utilization. Use of dynamic pricing also makes the scheme useful to increase revenue of the service providers in contrast with compared schemes.

Systematic Evaluation of Non-Uniform Sampling Parameters in the Targeted Analysis of Urine Metabolites by 1H,1H 2D NMR Spectroscopy.

Science.gov (United States)

Schlippenbach, Trixi von; Oefner, Peter J; Gronwald, Wolfram

2018-03-09

Non-uniform sampling (NUS) allows the accelerated acquisition of multidimensional NMR spectra. The aim of this contribution was the systematic evaluation of the impact of various quantitative NUS parameters on the accuracy and precision of 2D NMR measurements of urinary metabolites. Urine aliquots spiked with varying concentrations (15.6-500.0 µM) of tryptophan, tyrosine, glutamine, glutamic acid, lactic acid, and threonine, which can only be resolved fully by 2D NMR, were used to assess the influence of the sampling scheme, reconstruction algorithm, amount of omitted data points, and seed value on the quantitative performance of NUS in 1 H, 1 H-TOCSY and 1 H, 1 H-COSY45 NMR spectroscopy. Sinusoidal Poisson-gap sampling and a compressed sensing approach employing the iterative re-weighted least squares method for spectral reconstruction allowed a 50% reduction in measurement time while maintaining sufficient quantitative accuracy and precision for both types of homonuclear 2D NMR spectroscopy. Together with other advances in instrument design, such as state-of-the-art cryogenic probes, use of 2D NMR spectroscopy in large biomedical cohort studies seems feasible.

High harmonic terahertz confocal gyrotron with nonuniform electron beam

Energy Technology Data Exchange (ETDEWEB)

Fu, Wenjie; Guan, Xiaotong; Yan, Yang [THz Research Center, School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)

2016-01-15

The harmonic confocal gyrotron with nonuniform electron beam is proposed in this paper in order to develop compact and high power terahertz radiation source. A 0.56 THz third harmonic confocal gyrotron with a dual arc section nonuniform electron beam has been designed and investigated. The studies show that confocal cavity has extremely low mode density, and has great advantage to operate at high harmonic. Nonuniform electron beam is an approach to improve output power and interaction efficiency of confocal gyrotron. A dual arc beam magnetron injection gun for designed confocal gyrotron has been developed and presented in this paper.

Normal tissue complication probabilities: dependence on choice of biological model and dose-volume histogram reduction scheme

International Nuclear Information System (INIS)

Moiseenko, Vitali; Battista, Jerry; Van Dyk, Jake

2000-01-01

Purpose: To evaluate the impact of dose-volume histogram (DVH) reduction schemes and models of normal tissue complication probability (NTCP) on ranking of radiation treatment plans. Methods and Materials: Data for liver complications in humans and for spinal cord in rats were used to derive input parameters of four different NTCP models. DVH reduction was performed using two schemes: 'effective volume' and 'preferred Lyman'. DVHs for competing treatment plans were derived from a sample DVH by varying dose uniformity in a high dose region so that the obtained cumulative DVHs intersected. Treatment plans were ranked according to the calculated NTCP values. Results: Whenever the preferred Lyman scheme was used to reduce the DVH, competing plans were indistinguishable as long as the mean dose was constant. The effective volume DVH reduction scheme did allow us to distinguish between these competing treatment plans. However, plan ranking depended on the radiobiological model used and its input parameters. Conclusions: Dose escalation will be a significant part of radiation treatment planning using new technologies, such as 3-D conformal radiotherapy and tomotherapy. Such dose escalation will depend on how the dose distributions in organs at risk are interpreted in terms of expected complication probabilities. The present study indicates considerable variability in predicted NTCP values because of the methods used for DVH reduction and radiobiological models and their input parameters. Animal studies and collection of standardized clinical data are needed to ascertain the effects of non-uniform dose distributions and to test the validity of the models currently in use

Nonuniformities in organic liquid ionization calorimeters

International Nuclear Information System (INIS)

Wenzel, W.A.

1989-06-01

Hermeticity and uniformity in SSC calorimeter designs are compromised by structure and modularity. Some of the consequences of the cryogenic needs of liquid argon calorimetry are relatively well known. If the active medium is an organic liquid (TMP, TMS, etc.), a large number of independent liquid volumes is needed for safety and for rapid liquid exchange to eliminate local contamination. Modular construction ordinarily simplifies fabrication, assembly, handling and preliminary testing at the price of additional walls, other dead regions and many nonuniformities. Here we examine ways of minimizing the impact of some generic nonuniformities on the quality of calorimeter performance. 6 refs., 7 figs

Calculation of stresses and deformations in a cylindrical shell with imperfect initial shape and at the circumference nonuniform temperature

International Nuclear Information System (INIS)

Leonchuk, M.P.; Pyl'chenkov, Eh.Kh.; Dvortsova, L.I.

1976-01-01

A method is proposed for calculating the stress-strain state of a thin cylindrical shell with initial shape imperfections under conditions of peripheral nonuniformity of temperatures and a prolonged effect of external loads. The method is based on the plane deformation hypothesis, it takes into account geometrical nonlinearity and also the steady and nonsteady stages of creep. Different schemes are considered of the problem realization on the computer. The possibility of using the method for analyzing stresses, strains and lifetime of the fuel elements and other reactor elements is demonstrated

Non-uniformity Correction of Infrared Images by Midway Equalization

Directory of Open Access Journals (Sweden)

Yohann Tendero

2012-07-01

Full Text Available The non-uniformity is a time-dependent noise caused by the lack of sensor equalization. We present here the detailed algorithm and on line demo of the non-uniformity correction method by midway infrared equalization. This method was designed to suit infrared images. Nevertheless, it can be applied to images produced for example by scanners, or by push-broom satellites. The obtained single image method works on static images, is fully automatic, having no user parameter, and requires no registration. It needs no camera motion compensation, no closed aperture sensor equalization and is able to correct for a fully non-linear non-uniformity.

Temporal high-pass non-uniformity correction algorithm based on grayscale mapping and hardware implementation

Science.gov (United States)

Jin, Minglei; Jin, Weiqi; Li, Yiyang; Li, Shuo

2015-08-01

In this paper, we propose a novel scene-based non-uniformity correction algorithm for infrared image processing-temporal high-pass non-uniformity correction algorithm based on grayscale mapping (THP and GM). The main sources of non-uniformity are: (1) detector fabrication inaccuracies; (2) non-linearity and variations in the read-out electronics and (3) optical path effects. The non-uniformity will be reduced by non-uniformity correction (NUC) algorithms. The NUC algorithms are often divided into calibration-based non-uniformity correction (CBNUC) algorithms and scene-based non-uniformity correction (SBNUC) algorithms. As non-uniformity drifts temporally, CBNUC algorithms must be repeated by inserting a uniform radiation source which SBNUC algorithms do not need into the view, so the SBNUC algorithm becomes an essential part of infrared imaging system. The SBNUC algorithms' poor robustness often leads two defects: artifacts and over-correction, meanwhile due to complicated calculation process and large storage consumption, hardware implementation of the SBNUC algorithms is difficult, especially in Field Programmable Gate Array (FPGA) platform. The THP and GM algorithm proposed in this paper can eliminate the non-uniformity without causing defects. The hardware implementation of the algorithm only based on FPGA has two advantages: (1) low resources consumption, and (2) small hardware delay: less than 20 lines, it can be transplanted to a variety of infrared detectors equipped with FPGA image processing module, it can reduce the stripe non-uniformity and the ripple non-uniformity.

Skin carcinogenesis following uniform and non-uniform β irradiation

International Nuclear Information System (INIS)

Charles, M.W.; Williams, J.P.; Coggle, J.E.

1989-01-01

Where workers or the general public may be exposed to ionising radiation, the irradiation is rarely uniform. The risk figures and dose limits recommended by the International Commission on Radiological Protection (ICRP) are based largely on clinical and epidemiological studies of reasonably uniform irradiated organs. The paucity of clinical or experimental data for highly non-uniform exposures has prevented the ICRP from providing adequate recommendations. This weakness has led on a number of occasions to the postulate that highly non-uniform exposures of organs could be 100,000 times more carcinogenic than ICRP risk figures would predict. This so-called ''hot-particle hypothesis'' found little support among reputable radiobiologists, but could not be clearly and definitively refuted on the basis of experiment. An experiment, based on skin tumour induction in mouse skin, is described which was developed to test the hypothesis. The skin of 1200 SAS/4 male mice has been exposed to a range of uniform and non-uniform sources of the β emitter 170 Tm (E max ∼ 1 MeV). Non-uniform exposures were produced using arrays of 32 or 8 2-mm diameter sources distributed over the same 8-cm 2 area as a uniform control source. Average skin doses varied from 2-100 Gy. The results for the non-uniform sources show a 30% reduction in tumour incidence by the 32-point array at the lower mean doses compared with the response from uniform sources. The eight-point array showed an order-of-magnitude reduction in tumour incidence compared to uniform irradiation at low doses. These results, in direct contradiction to the ''hot particle hypothesis'', indicate that non-uniform exposures produce significantly fewer tumours than uniform exposures. (author)

Vortices in nonuniform upper-hybrid field

International Nuclear Information System (INIS)

Davydova, T.A.; Vranjes, J.

1992-01-01

The equations describing the interaction of an upper-hybrid pump wave with small low-frequency density perturbations are discussed under assumption that the pump is spatially nonuniform. The conditions for the modulational instability are investigated. Instead of a dispersion relation, describing the growth of perturbations in the case of an uniform pump, in our case of nonuniform pump a differential equation is obtained and from its eigenvalues are found the instability criteria. Taking into account the slow-frequency self-interaction terms some localized solutions similar to dipole vortices are found, but described by analytic functions in all space. It is shown that their characteristic size and speed are determined by the pump intensity and its spatial structure. (au)

Below-threshold harmonic generation from strong non-uniform fields

Science.gov (United States)

Yavuz, I.

2017-10-01

Strong-field photoemission below the ionization threshold is a rich/complex region where atomic emission and harmonic generation may coexist. We studied the mechanism of below-threshold harmonics (BTH) from spatially non-uniform local fields near the metallic nanostructures. Discrete harmonics are generated due to the broken inversion symmetry, suggesting enriched coherent emission in the vuv frequency range. Through the numerical solution of the time-dependent Schrödinger equation, we investigate wavelength and intensity dependence of BTH. Wavelength dependence identifies counter-regular resonances; individual contributions from the multi-photon emission and channel-closing effects due to quantum path interferences. In order to understand the underlying mechanism of BTH, we devised a generalized semi-classical model, including the influence of Coulomb and non-uniform field interactions. As in uniform fields, Coulomb potential in non-uniform fields is the determinant of BTH; we observed that the generation of BTH are due to returning trajectories with negative energies. Due to large distance effectiveness of the non-uniformity, only long trajectories are noticeably affected.

A method to measure the mean thickness and non-uniformity of non-uniform thin film by alpha-ray thickness gauge

International Nuclear Information System (INIS)

Miyahara, Hiroshi; Yoshida, Makoto; Watanabe, Tamaki

1977-01-01

The α-ray thickness gauge is used to measure non-destructively the thicknesses of thin films, and up to the present day, a thin film with uniform thickness is only taken up as the object of α-ray thickness gauge. When the thickness is determined from the displacement between the absorption curves in the presence and absence of thin film, the absorption curve must be displaced in parallel. When many uniform particles were dispersed as sample, the shape of the absorption curve was calculated as the sum of many absorption curves corresponding to the thin films with different thicknesses. By the comparison of the calculated and measured absorption curves, the number of particles, or the mean superficial density can be determined. This means the extension of thickness measurement from uniform to non-uniform films. Furthermore, these particle models being applied to non-uniform thin film, the possibility of measuring the mean thickness and non-uniformity was discussed. As the result, if the maximum difference of the thickness was more than 0.2 mg/cm 2 , the nonuniformity was considered to distinguish by the usual equipment. In this paper, an α-ray thickness gauge using the absorption curve method was treated, but one can apply this easily to an α-ray thickness gauge using α-ray energy spectra before and after the penetration of thin film. (auth.)

Design of Nonuniform Filter Bank Transceivers for Frequency Selective Channels

Directory of Open Access Journals (Sweden)

Yuan-Pei Lin

2007-01-01

Full Text Available In recent years, there has been considerable interest in the theory and design of filter bank transceivers due to their superior frequency response. In many applications, it is desired to have transceivers that can support multiple services with different incoming data rates and different quality-of-service requirements. To meet these requirements, we can either do resource allocation or design transceivers with a nonuniform bandwidth partition. In this paper, we propose a method for the design of nonuniform filter bank transceivers for frequency selective channels. Both frequency response and signal-to-interference ratio (SIR can be incorporated in the transceiver design. Moreover, the technique can be extended to the case of nonuniform filter bank transceivers with rational sampling factors. Simulation results show that nonuniform filter bank transceivers with good filter responses as well as high SIR can be obtained by the proposed design method.

Non-uniformity calibration for MWIR polarization imagery obtained with integrated microgrid polarimeters

Science.gov (United States)

Liu, Hai-Zheng; Shi, Ze-Lin; Feng, Bin; Hui, Bin; Zhao, Yao-Hong

2016-03-01

Integrating microgrid polarimeters on focal plane array (FPA) of an infrared detector causes non-uniformity of polarization response. In order to reduce the effect of polarization non-uniformity, this paper constructs an experimental setup for capturing raw flat-field images and proposes a procedure for acquiring non-uniform calibration (NUC) matrix and calibrating raw polarization images. The proposed procedure takes the incident radiation as a polarization vector and offers a calibration matrix for each pixel. Both our matrix calibration and two-point calibration are applied to our mid-wavelength infrared (MWIR) polarization imaging system with integrated microgrid polarimeters. Compared with two point calibration, our matrix calibration reduces non-uniformity by 30 40% under condition of flat-field data test with polarization. The ourdoor scene observation experiment indicates that our calibration can effectively reduce polarization non-uniformity and improve the image quality of our MWIR polarization imaging system.

Non-uniform tube representation of proteins

DEFF Research Database (Denmark)

Hansen, Mikael Sonne

Treating the full protein structure is often neither computationally nor physically possible. Instead one is forced to consider various reduced models capturing the properties of interest. Previous work have used tubular neighborhoods of the C-alpha backbone. However, assigning a unique radius...... might not correctly capture volume exclusion - of crucial importance when trying to understand a proteins $3$d-structure. We propose a new reduced model treating the protein as a non-uniform tube with a radius reflecting the positions of atoms. The tube representation is well suited considering X......-ray crystallographic resolution ~ 3Å while a varying radius accounts for the different sizes of side chains. Such a non-uniform tube better capture the protein geometry and has numerous applications in structural/computational biology from the classification of protein structures to sequence-structure prediction....

A full quantum network scheme

International Nuclear Information System (INIS)

Ma Hai-Qiang; Wei Ke-Jin; Yang Jian-Hui; Li Rui-Xue; Zhu Wu

2014-01-01

We present a full quantum network scheme using a modified BB84 protocol. Unlike other quantum network schemes, it allows quantum keys to be distributed between two arbitrary users with the help of an intermediary detecting user. Moreover, it has good expansibility and prevents all potential attacks using loopholes in a detector, so it is more practical to apply. Because the fiber birefringence effects are automatically compensated, the scheme is distinctly stable in principle and in experiment. The simple components for every user make our scheme easier for many applications. The experimental results demonstrate the stability and feasibility of this scheme. (general)

Field nonuniformity correction for quantitative analysis of digitized mammograms

International Nuclear Information System (INIS)

Pawluczyk, Olga; Yaffe, Martin J.

2001-01-01

Several factors, including the heel effect, variation in distance from the x-ray source to points in the image and path obliquity contribute to the signal nonuniformity of mammograms. To best use digitized mammograms for quantitative image analysis, these field non-uniformities must be corrected. An empirically based correction method, which uses a bowl-shaped calibration phantom, has been developed. Due to the annular spherical shape of the phantom, its attenuation is constant over the entire image. Remaining nonuniformities are due only to the heel and inverse square effects as well as the variable path through the beam filter, compression plate and image receptor. In logarithmic space, a normalized image of the phantom can be added to mammograms to correct for these effects. Then, an analytical correction for path obliquity in the breast can be applied to the images. It was found that the correction causes the errors associated with field nonuniformity to be reduced from 14% to 2% for a 4 cm block of material corresponding to a combination of 50% fibroglandular and 50% fatty breast tissue. A repeatability study has been conducted to show that in regions as far as 20 cm away from the chest wall, variations due to imaging conditions and phantom alignment contribute to <2% of overall corrected signal

Numerical modeling of positive streamer in air in nonuniform fields: Efficiency of radicals production

International Nuclear Information System (INIS)

Kulikovsky, A.A.

2001-01-01

The efficiency of streamer corona depends on a number of factors such as geometry of electrodes, voltage pulse parameters, gas pressure etc. In a past 5 years a two-dimensional models of streamer in nonuniform fields in air have been developed. These models allow to simulate streamer dynamics and generation of species and to investigate the influence of external parameters on species production. In this work the influence of Laplacian field on efficiency of radicals generation is investigated

Parallel processing and non-uniform grids in global air quality modeling

NARCIS (Netherlands)

Berkvens, P.J.F.; Bochev, Mikhail A.

2002-01-01

A large-scale global air quality model, running efficiently on a single vector processor, is enhanced to make more realistic and more long-term simulations feasible. Two strategies are combined: non-uniform grids and parallel processing. The communication through the hierarchy of non-uniform grids

Space cutter compensation method for five-axis nonuniform rational basis spline machining

Directory of Open Access Journals (Sweden)

Yanyu Ding

2015-07-01

Full Text Available In view of the good machining performance of traditional three-axis nonuniform rational basis spline interpolation and the space cutter compensation issue in multi-axis machining, this article presents a triple nonuniform rational basis spline five-axis interpolation method, which uses three nonuniform rational basis spline curves to describe cutter center location, cutter axis vector, and cutter contact point trajectory, respectively. The relative position of the cutter and workpiece is calculated under the workpiece coordinate system, and the cutter machining trajectory can be described precisely and smoothly using this method. The three nonuniform rational basis spline curves are transformed into a 12-dimentional Bézier curve to carry out discretization during the discrete process. With the cutter contact point trajectory as the precision control condition, the discretization is fast. As for different cutters and corners, the complete description method of space cutter compensation vector is presented in this article. Finally, the five-axis nonuniform rational basis spline machining method is further verified in a two-turntable five-axis machine.

Downsampling Non-Uniformly Sampled Data

Directory of Open Access Journals (Sweden)

Fredrik Gustafsson

2007-10-01

Full Text Available Decimating a uniformly sampled signal a factor D involves low-pass antialias filtering with normalized cutoff frequency 1/D followed by picking out every Dth sample. Alternatively, decimation can be done in the frequency domain using the fast Fourier transform (FFT algorithm, after zero-padding the signal and truncating the FFT. We outline three approaches to decimate non-uniformly sampled signals, which are all based on interpolation. The interpolation is done in different domains, and the inter-sample behavior does not need to be known. The first one interpolates the signal to a uniformly sampling, after which standard decimation can be applied. The second one interpolates a continuous-time convolution integral, that implements the antialias filter, after which every Dth sample can be picked out. The third frequency domain approach computes an approximate Fourier transform, after which truncation and IFFT give the desired result. Simulations indicate that the second approach is particularly useful. A thorough analysis is therefore performed for this case, using the assumption that the non-uniformly distributed sampling instants are generated by a stochastic process.

Evaluation of nonuniform field exposures with coupling factors

International Nuclear Information System (INIS)

Sunohara, Tetsu; Hirata, Akimasa; Laakso, Ilkka; De Santis, Valerio; Onishi, Teruo

2015-01-01

In this study, the safety compliance for nonuniform field exposures is discussed using coupling factor concepts. The coupling factor, which is defined in the International Electrotechnical Commission 62311 standard, is extended to consider the effects of harmonics and also to apply to the specific absorption rate (for frequencies up to 30 MHz). The proposed compliance procedure is applied to and demonstrated for a prototype wireless power transfer (WPT) system with induction coupling operating at the fundamental frequency in 140 kHz band. First, measurements confirm that the perturbation of the external magnetic field strength and S 11 parameter of a one-loop antenna by a human-equivalent phantom are sufficiently small, suggesting the applicability of the magneto-quasi-static approximation to frequencies up to 30 MHz. Then, the frequency characteristics of the coupling factor are derived for the WPT system. For the prototype system that is not optimized for commercial usage, the maximum allowable transmitting power is relaxed by a factor of 23 with the proposed procedure. The contribution of the harmonics decreased the allowable transmitting power by 39%, indicating their importance for safety compliance. (paper)

Evaluation of nonuniform field exposures with coupling factors.

Science.gov (United States)

Sunohara, Tetsu; Hirata, Akimasa; Laakso, Ilkka; De Santis, Valerio; Onishi, Teruo

2015-10-21

In this study, the safety compliance for nonuniform field exposures is discussed using coupling factor concepts. The coupling factor, which is defined in the International Electrotechnical Commission 62311 standard, is extended to consider the effects of harmonics and also to apply to the specific absorption rate (for frequencies up to 30 MHz). The proposed compliance procedure is applied to and demonstrated for a prototype wireless power transfer (WPT) system with induction coupling operating at the fundamental frequency in 140 kHz band. First, measurements confirm that the perturbation of the external magnetic field strength and S11 parameter of a one-loop antenna by a human-equivalent phantom are sufficiently small, suggesting the applicability of the magneto-quasi-static approximation to frequencies up to 30 MHz. Then, the frequency characteristics of the coupling factor are derived for the WPT system. For the prototype system that is not optimized for commercial usage, the maximum allowable transmitting power is relaxed by a factor of 23 with the proposed procedure. The contribution of the harmonics decreased the allowable transmitting power by 39%, indicating their importance for safety compliance.

Enhanced finite difference scheme for the neutron diffusion equation using the importance function

International Nuclear Information System (INIS)

Vagheian, Mehran; Vosoughi, Naser; Gharib, Morteza

2016-01-01

Highlights: • An enhanced finite difference scheme for the neutron diffusion equation is proposed. • A seven-step algorithm is considered based on the importance function. • Mesh points are distributed through entire reactor core with respect to the importance function. • The results all proved that the proposed algorithm is highly efficient. - Abstract: Mesh point positions in Finite Difference Method (FDM) of discretization for the neutron diffusion equation can remarkably affect the averaged neutron fluxes as well as the effective multiplication factor. In this study, by aid of improving the mesh point positions, an enhanced finite difference scheme for the neutron diffusion equation is proposed based on the neutron importance function. In order to determine the neutron importance function, the adjoint (backward) neutron diffusion calculations are performed in the same procedure as for the forward calculations. Considering the neutron importance function, the mesh points can be improved through the entire reactor core. Accordingly, in regions with greater neutron importance, density of mesh elements is higher than that in regions with less importance. The forward calculations are then performed for both of the uniform and improved non-uniform mesh point distributions and the results (the neutron fluxes along with the corresponding eigenvalues) for the two cases are compared with each other. The results are benchmarked against the reference values (with fine meshes) for Kang and Rod Bundle BWR benchmark problems. These benchmark cases revealed that the improved non-uniform mesh point distribution is highly efficient.

Further Development of Ko Displacement Theory for Deformed Shape Predictions of Nonuniform Aerospace Structures

Science.gov (United States)

Ko, William L.; Fleischer, Van Tran

2009-01-01

The Ko displacement theory previously formulated for deformed shape predictions of nonuniform beam structures is further developed mathematically. The further-developed displacement equations are expressed explicitly in terms of geometrical parameters of the beam and bending strains at equally spaced strain-sensing stations along the multiplexed fiber-optic sensor line installed on the bottom surface of the beam. The bending strain data can then be input into the displacement equations for calculations of local slopes, deflections, and cross-sectional twist angles for generating the overall deformed shapes of the nonuniform beam. The further-developed displacement theory can also be applied to the deformed shape predictions of nonuniform two-point supported beams, nonuniform panels, nonuniform aircraft wings and fuselages, and so forth. The high degree of accuracy of the further-developed displacement theory for nonuniform beams is validated by finite-element analysis of various nonuniform beam structures. Such structures include tapered tubular beams, depth-tapered unswept and swept wing boxes, width-tapered wing boxes, and double-tapered wing boxes, all under combined bending and torsional loads. The Ko displacement theory, combined with the fiber-optic strain-sensing system, provide a powerful tool for in-flight deformed shape monitoring of unmanned aerospace vehicles by ground-based pilots to maintain safe flights.

Laguerre-Freud equations for the recurrence coefficients of the Laguerre-Hahn orthogonal polynomials on special nonuniform lattices

International Nuclear Information System (INIS)

Bangerezako, Gaspard; Foupouagnigni, Mama

2003-10-01

We give an algorithmic derivation of the Laguerre-Freud equations for the recurrence coefficients β n and γ n of the Laguerre-Hahn orthogonal polynomials on special nonuniform lattices. This algorithm is the most general one since it is valid for the Laguerre-Hahn orthogonal polynomials of any class k, on the special nonuniform lattices including the continuous (limiting cases), linear, q-linear and the q-nonlinear ones. Moreover, the algorithm allows to deduce an upper bound for the order of the equations in β n and γ n , which is respectively 2 k + 2 and 2 k + 3 when k is even, or 2 k + 3 and 2 k + 2 when k is odd. Finally, as applications, we discuss explicitly these equations for k = 1 in the continuous and linear cases, and k = 2 in the continuous symmetric one. (author)

Interest of seeing Precision Viticulture through two distributed competences: Determination of resources and schemes allowing some practical recommendations

Directory of Open Access Journals (Sweden)

Moreiro Leslie B.

2017-01-01

Full Text Available The aim of this article is to better understand resources needed and constraints to avoid in implementation of Precision Viticulture technologies. In this view, we adapt distributed cognition theory to multilevel model of competence in management sciences. We use a qualitative methodology based on semi-structured interviews in 7 cases study. The main results allow us to distinguish the two aspects of Precision Viticulture, artifacts, providers of resources, and their utilization scheme. Furthermore, Precision Viticulture is decomposed here in two tasks. The first task is characterization of heterogeneity. The second is modulation of technical itineraries. These two tasks are complementary. In addition, we present ours results by highlighting resources used by firm using these technologies and constraints that they face. Finally, with these results, we can do some practical recommendations to designers and users of these technologies.

Investigation of the Periodic Absolute Parametric Instability in a Nonuniform Cylindrical Warm Plasma Waveguide

International Nuclear Information System (INIS)

Zaki, N.G.

2009-01-01

In this paper, the effect of spatial plasma nonuniformity on periodic Absolute Parametric Instability (API) of electrostatic waves in a magnetized pump warm plasma is investigated in a cylindrical geometry. An API plays a crucial role in the processes of the energy transfer from the electromagnetic radiation to the plasma and may have an important consequences for experiments on RF plasma heating in a magnetic traps and for a laser-fusion system. In conclusion; it is found that: A) allowance for the spatial nonuniformity of the plasma density leads to A.I) localization of an unstable wave in a finite region of a plasma volume, A.2) increasing the threshold value of the pump wave amplitude above which parametric amplification occurs and A.3) decreasing the value of the growth rate of unstable waves, B) more growth rate of periodic API is decreased due to electrons warmness in comparison with the case of cold plasma, and C) Independent of the geometry of the problem ( plane or cylinder), the results of the API in a warm plasma waveguide are still valid

The magnetostriction in a superconductor-magnet system under non-uniform magnetic field

Energy Technology Data Exchange (ETDEWEB)

Li, Xueyi; Jiang, Lang; Wu, Hao [Key Laboratory of Mechanics on Disaster and Environment in Western China attached to the Ministry of Education of China, Lanzhou University, Lanzhou, Gansu 730000 (China); Gao, Zhiwen, E-mail: gaozhw@lzu.edu.cn [Department of Mechanics and Engineering Science, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000 (China)

2017-03-15

Highlights: • We studied firstly magnetostriction in HTS under non-uniform magnetic field. • The superconductors may be homogeneous and nonhomogeneous. • The magnetostrictions response of the HTS is sensitive to the critical current density and amplitude of the applied magnetic field. • The magnetostriction of nonhomogeneous HTS is larger than that of homogeneous HTS. - Abstract: This paper describes a numerical model to examine the magnetostriction of bulk high-temperature superconductor (HTS) under non-uniform magnetic field in conjunction with finite element analysis. Through this model, the magnetostriction of homogeneous and nonhomogeneous HTS can be implemented under non-uniform magnetic field. Further, the effects of critical current density, applied field frequency and amplitude are also considered. The computational study can provide a fundamental mechanistic understanding the effects of non-uniform magnetic field on magnetostriction of HTS.

Modelling of HVDC wall bushing flashover in nonuniform rain

International Nuclear Information System (INIS)

Rizk, F.A.M.; Kamel, S.I.

1991-01-01

This paper presents the first mathematical model to provide necessary and sufficient conditions for flashover of an HVDC wall bushing under nonuniform rain. The suggested mechanism is initiated by streamer bridging of the dry zone enhanced by nonuniform voltage distribution along the bushing and within the dry zone. Fast voltage collapse across the dry zone die to energy stored in the bushing stray capacitance to ground leads to impulsive stressing of the wet part of the bushing. The nonuniform distribution of the impulse stress and the process of streamer bridging, fast voltage collapse as well as subsequent recharging of the bushing capacitances can lead to continued discharge propagation and flashover of the complete bushing. The findings of the model have been satisfactorily compared with previous experiments and field observations and can, for the first time, account for the following aspects of the flashover mechanism: critical dry zone length, polarity effect, specific leakage path, wet layer conductance per unit leakage length as well as the DC system voltage

Stone Stability in Non-uniform Flow

NARCIS (Netherlands)

Hoan, N.T.; Stive, M.J.F.; Booij, R.; Hofland, B.; Verhagen, H.J.

2011-01-01

This paper presents the results of an experimental study on stone stability under nonuniform turbulent flow, in particular expanding flow. Detailed measurements of both flow and turbulence and the bed stability are described. Than various manners of quantifying the hydraulic loads exerted on the

Stone Stability under Stationary Nonuniform Flows

NARCIS (Netherlands)

Steenstra, Remco; Hofland, B.; Paarlberg, Andries; Smale, Alfons; Huthoff, Fredrik; Uijttewaal, W.S.J.

2016-01-01

A stability parameter for rock in bed protections under nonuniform stationary flow is derived. The influence of the mean flow velocity, turbulence, and mean acceleration of the flow are included explicitly in the parameter. The relatively new notion of explicitly incorporating the mean acceleration

Charged particle acceleration in nonuniform plasmas

International Nuclear Information System (INIS)

Bulanov, S.V.; Naumova, N.M.; Pegoraro, F.

1996-11-01

The high-gradient electron acceleration schemes that have been demonstrated using LWFA appear promising for the development of plasma-based laser accelerators into practical devices. However, a question still exists: how to avoid the wake field deterioration and the loss of the phase synchronism between the plasma wave and the electrons that prevent them from being accelerated up to the theoretical limit. In order to obtain the highest possible values of the wake electric field one must use as intense laser pulses as possible i.e., pulses with dimensionless amplitudes a much-gt 1. Pulses that have a dimensionless amplitude larger than one tend to be subject to a host of instabilities, such as relativistic self-focusing, self modulation and stimulated Raman scattering, that affect their propagation in the plasma. Such processes could be beneficial, in so far as they increase the pulse energy density, enhance the wake field generation, and provide the mechanism for transporting the laser radiation over several Rayleigh lengths without diffraction spreading. However, it is still far from certain that these processes can be exploited in a controlled form and can lead to regular, stationary wake fields. It is known that, in order to create good quality wake fields, it would be preferable to use laser pulses with steep fronts of order λ p . The present paper aims at analyzing the influence of the laser pulse shape and of the plasma nonuniformity on the charged particle acceleration. This study is based on the results obtained with one dimensional PIC simulations

An improved non-uniformity correction algorithm and its GPU parallel implementation

Science.gov (United States)

Cheng, Kuanhong; Zhou, Huixin; Qin, Hanlin; Zhao, Dong; Qian, Kun; Rong, Shenghui

2018-05-01

The performance of SLP-THP based non-uniformity correction algorithm is seriously affected by the result of SLP filter, which always leads to image blurring and ghosting artifacts. To address this problem, an improved SLP-THP based non-uniformity correction method with curvature constraint was proposed. Here we put forward a new way to estimate spatial low frequency component. First, the details and contours of input image were obtained respectively by minimizing local Gaussian curvature and mean curvature of image surface. Then, the guided filter was utilized to combine these two parts together to get the estimate of spatial low frequency component. Finally, we brought this SLP component into SLP-THP method to achieve non-uniformity correction. The performance of proposed algorithm was verified by several real and simulated infrared image sequences. The experimental results indicated that the proposed algorithm can reduce the non-uniformity without detail losing. After that, a GPU based parallel implementation that runs 150 times faster than CPU was presented, which showed the proposed algorithm has great potential for real time application.

Determination of Solution Accuracy of Numerical Schemes as Part of Code and Calculation Verification

Energy Technology Data Exchange (ETDEWEB)

Blottner, F.G.; Lopez, A.R.

1998-10-01

This investigation is concerned with the accuracy of numerical schemes for solving partial differential equations used in science and engineering simulation codes. Richardson extrapolation methods for steady and unsteady problems with structured meshes are presented as part of the verification procedure to determine code and calculation accuracy. The local truncation error de- termination of a numerical difference scheme is shown to be a significant component of the veri- fication procedure as it determines the consistency of the numerical scheme, the order of the numerical scheme, and the restrictions on the mesh variation with a non-uniform mesh. Genera- tion of a series of co-located, refined meshes with the appropriate variation of mesh cell size is in- vestigated and is another important component of the verification procedure. The importance of mesh refinement studies is shown to be more significant than just a procedure to determine solu- tion accuracy. It is suggested that mesh refinement techniques can be developed to determine con- sistency of numerical schemes and to determine if governing equations are well posed. The present investigation provides further insight into the conditions and procedures required to effec- tively use Richardson extrapolation with mesh refinement studies to achieve confidence that sim- ulation codes are producing accurate numerical solutions.

High-order nonuniformly correlated beams

Science.gov (United States)

Wu, Dan; Wang, Fei; Cai, Yangjian

2018-02-01

We have introduced a class of partially coherent beams with spatially varying correlations named high-order nonuniformly correlated (HNUC) beams, as an extension of conventional nonuniformly correlated (NUC) beams. Such beams bring a new parameter (mode order) which is used to tailor the spatial coherence properties. The behavior of the spectral density of the HNUC beams on propagation has been investigated through numerical examples with the help of discrete model decomposition and fast Fourier transform (FFT) algorithm. Our results reveal that by selecting the mode order appropriately, the more sharpened intensity maxima can be achieved at a certain propagation distance compared to that of the NUC beams, and the lateral shift of the intensity maxima on propagation is closed related to the mode order. Furthermore, analytical expressions for the r.m.s width and the propagation factor of the HNUC beams on free-space propagation are derived by means of Wigner distribution function. The influence of initial beam parameters on the evolution of the r.m.s width and the propagation factor, and the relation between the r.m.s width and the occurring of the sharpened intensity maxima on propagation have been studied and discussed in detail.

Assessment indices for uniform and non-uniform thermal environments

Institute of Scientific and Technical Information of China (English)

2008-01-01

Different assessment indices for thermal environments were compared and selected for proper assessment of indoor thermal environments.30 subjects reported their overall thermal sensation,thermal comfort,and thermal acceptability in uniform and non-uniform conditions.The results show that these three assessment indices provide equivalent evaluations in uniform environments.However,overall thermal sensation differs from the other two indices and cannot be used as a proper index for the evaluation of non-uniform environments.The relationship between the percentage and the mean vote for each index is established.

On natural frequencies of non-uniform beams modulated by finite periodic cells

International Nuclear Information System (INIS)

Xu, Yanlong; Zhou, Xiaoling; Wang, Wei; Wang, Longqi; Peng, Fujun; Li, Bin

2016-01-01

It is well known that an infinite periodic beam can support flexural wave band gaps. However, in real applications, the number of the periodic cells is always limited. If a uniform beam is replaced by a non-uniform beam with finite periodicity, the vibration changes are vital by mysterious. This paper employs the transfer matrix method (TMM) to study the natural frequencies of the non-uniform beams with modulation by finite periodic cells. The effects of the amounts, cross section ratios, and arrangement forms of the periodic cells on the natural frequencies are explored. The relationship between the natural frequencies of the non-uniform beams with finite periodicity and the band gap boundaries of the corresponding infinite periodic beam is also investigated. Numerical results and conclusions obtained here are favorable for designing beams with good vibration control ability. - Highlights: • The transfer matrix method to study the natural frequencies of the finite periodic non-uniform beams is derived. • The transfer matrix method to study the band gaps of the infinite periodic non-uniform beams is derived. • The effects of the periodic cells on the natural frequencies are explored. • The relationships of the natural frequencies and band gap boundaries are investigated.

On natural frequencies of non-uniform beams modulated by finite periodic cells

Energy Technology Data Exchange (ETDEWEB)

Xu, Yanlong, E-mail: xuyanlong@nwpu.edu.cn [School of Aeronautics, Northwestern Polytechnical University, Xi' an 710072, Shaanxi (China); Zhou, Xiaoling [Shanghai Institute of Aerospace System Engineering, Shanghai 201109 (China); Wang, Wei [School of Aeronautics, Northwestern Polytechnical University, Xi' an 710072, Shaanxi (China); Wang, Longqi [School of Civil & Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Peng, Fujun [Shanghai Institute of Aerospace System Engineering, Shanghai 201109 (China); Li, Bin [School of Aeronautics, Northwestern Polytechnical University, Xi' an 710072, Shaanxi (China)

2016-09-23

It is well known that an infinite periodic beam can support flexural wave band gaps. However, in real applications, the number of the periodic cells is always limited. If a uniform beam is replaced by a non-uniform beam with finite periodicity, the vibration changes are vital by mysterious. This paper employs the transfer matrix method (TMM) to study the natural frequencies of the non-uniform beams with modulation by finite periodic cells. The effects of the amounts, cross section ratios, and arrangement forms of the periodic cells on the natural frequencies are explored. The relationship between the natural frequencies of the non-uniform beams with finite periodicity and the band gap boundaries of the corresponding infinite periodic beam is also investigated. Numerical results and conclusions obtained here are favorable for designing beams with good vibration control ability. - Highlights: • The transfer matrix method to study the natural frequencies of the finite periodic non-uniform beams is derived. • The transfer matrix method to study the band gaps of the infinite periodic non-uniform beams is derived. • The effects of the periodic cells on the natural frequencies are explored. • The relationships of the natural frequencies and band gap boundaries are investigated.

Gyrokinetic approach to the propagation of electromagnetic waves in nonuniform bounded plasma slabs

International Nuclear Information System (INIS)

Sauter, O.; Vaclavik, J.

1994-05-01

A new code, SEMAL, has been developed which solves the linearized Vlasov-Maxwell wave equations to all orders in Larmor radii. Arbitrary density and temperature profiles as well as nonuniform magnetic fields are considered in slab geometry. The vacuum regions adjacent to the plasma slab are limited by perfect conducting walls and contain an antenna as an excitation source. The linear response is obtained by solving the system of one first-order and two second-order integro-differential equations using a non-polluting finite element discretization. The general equations in the Fourier space, derived in a new comprehensive way, and their inverse transform, using k y =0, are described as well as the convergence and non-polluting properties of the method. We present the results concerning the influence of alpha particles on ICRF heating schemes for ITER, where we show that small alphas concentration can alter the steady-state operation envisaged with ICRF fast wave current-drive. (author) 7 figs., 3 tabs., 28 refs

Capacitated Vehicle Routing with Nonuniform Speeds

DEFF Research Database (Denmark)

Gørtz, Inge Li; Molinaro, Marco; Nagarajan, Viswanath

2016-01-01

is the distance traveled divided by its speed.Our algorithm relies on a new approximate minimum spanning tree construction called Level-Prim, which is related to but different from Light Approximate Shortest-path Trees. We also extend the widely used tour-splitting technique to nonuniform speeds, using ideas from...

Harmonisation between National and International Tradeable Permit Schemes. CATEP Synthesis Paper

International Nuclear Information System (INIS)

Haites, E.

2003-01-01

It is technically possible to link national emissions trading schemes with widely divergent designs. Where design differences create potential problems, technical solutions are available. The greater the similarity of their designs, the easier schemes are to link. During the 2005 - 2007 period the EU Directive, if it is adopted, will lead to the establishment of at least 25 national emissions trading schemes. The Directive specifies many of the design features of these schemes, but leaves the allocation of allowances, rules for banking allowances into the commitment period, use of the opt-out provision, and a few other design features to Member States. The resulting differences among Member State schemes are unlikely to undermine the links between the schemes established by the Directive. The Community may enter into agreements with non-members for mutual recognition of allowances between their emissions trading schemes, but few, if any, links of this type are expected prior to 2008 for practical reasons. Beginning in 2008, Article 17 of the Kyoto Protocol establishes an international emissions trading scheme that can link the national trading schemes of Annex I Parties. It imposes no requirements for harmonisation on the national emissions trading schemes linked. Some design differences could create technical problems, although solutions are available and at least one of the governments involved has an incentive to solve the problem. Adverse competitiveness impacts due to differences in the distribution of allowances across national schemes may need to be addressed through institutions such as the WTO. Most of the national trading schemes will also be subject to the EU Directive and be subject to greater harmonisation after 2008. The result is likely to be a progressive expansion and integration of greenhouse gas allowance markets over the next decade

Nonuniform charging effects on ion drag force in drifting dusty plasmas

International Nuclear Information System (INIS)

Chang, Dong-Man; Chang, Won-Seok; Jung, Young-Dae

2006-01-01

The nonuniform polarization charging effects on the ion drag force are investigated in drifting dusty plasmas. The ion drag force due to the ion-dust grain interaction is obtained as a function of the dust charge, ion charge, plasma temperature, Mach number, Debye length, and collision energy. The result shows that the nonuniform charging effects enhance the momentum transfer cross section as well as the ion drag force. It is found that the momentum transfer cross section and the ion drag force including nonuniform polarization charging effects increase with increasing the Mach number and also the ion drag force increases with increasing the temperature. In addition, it is found that the ion drag force is slightly decreasing with an increase of the Debye length

The effect of non-uniform fuel rod temperatures on effective resonance integrals

International Nuclear Information System (INIS)

Reichel, A.

1961-06-01

The effective resonance integral for heterogeneous lattices can be reduced to the effective resonance integral for an equivalent homogeneous system with a fairly well defined error depending on lump size and geometry. This report investigates the effect of a radial parabolic temperature variation in cylindrical lumps on the equivalent homogeneous effective resonance integral. Also determined is the equivalent uniform temperature to be taken in the usual formulae to allow for non-uniform fuel rod temperature. This effective temperature is found to be T eff. = T s + 4/9 (T c - T s ) where T s and T c are the surface and central temperatures of the lump. (author)

Making It Personal: Per Capita Carbon Allowances

DEFF Research Database (Denmark)

Fawcett, Tina; Hvelplund, Frede; Meyer, Niels I

2009-01-01

The Chapter highligts the importance of introducing new, efficient schemes for mitigation of global warming. One such scheme is Personal Carbon Allowances (PCA), whereby individuals are allotted a tradable ration of CO2 emission per year.This chapter reviews the fundamentals of PCA and analyzes its...... merits and problems. The United Kingdom and Denmark have been chosen as case studies because the energy situation and the institutional setup are quite different between the two countries....

Spatial model of the gecko foot hair: functional significance of highly specialized non-uniform geometry.

Science.gov (United States)

Filippov, Alexander E; Gorb, Stanislav N

2015-02-06

One of the important problems appearing in experimental realizations of artificial adhesives inspired by gecko foot hair is so-called clusterization. If an artificially produced structure is flexible enough to allow efficient contact with natural rough surfaces, after a few attachment-detachment cycles, the fibres of the structure tend to adhere one to another and form clusters. Normally, such clusters are much larger than original fibres and, because they are less flexible, form much worse adhesive contacts especially with the rough surfaces. Main problem here is that the forces responsible for the clusterization are the same intermolecular forces which attract fibres to fractal surface of the substrate. However, arrays of real gecko setae are much less susceptible to this problem. One of the possible reasons for this is that ends of the seta have more sophisticated non-uniformly distributed three-dimensional structure than that of existing artificial systems. In this paper, we simulated three-dimensional spatial geometry of non-uniformly distributed branches of nanofibres of the setal tip numerically, studied its attachment-detachment dynamics and discussed its advantages versus uniformly distributed geometry.

A DSP-based neural network non-uniformity correction algorithm for IRFPA

Science.gov (United States)

Liu, Chong-liang; Jin, Wei-qi; Cao, Yang; Liu, Xiu

2009-07-01

An effective neural network non-uniformity correction (NUC) algorithm based on DSP is proposed in this paper. The non-uniform response in infrared focal plane array (IRFPA) detectors produces corrupted images with a fixed-pattern noise(FPN).We introduced and analyzed the artificial neural network scene-based non-uniformity correction (SBNUC) algorithm. A design of DSP-based NUC development platform for IRFPA is described. The DSP hardware platform designed is of low power consumption, with 32-bit fixed point DSP TMS320DM643 as the kernel processor. The dependability and expansibility of the software have been improved by DSP/BIOS real-time operating system and Reference Framework 5. In order to realize real-time performance, the calibration parameters update is set at a lower task priority then video input and output in DSP/BIOS. In this way, calibration parameters updating will not affect video streams. The work flow of the system and the strategy of real-time realization are introduced. Experiments on real infrared imaging sequences demonstrate that this algorithm requires only a few frames to obtain high quality corrections. It is computationally efficient and suitable for all kinds of non-uniformity.

Testing for Nonuniform Differential Item Functioning with Multiple Indicator Multiple Cause Models

Science.gov (United States)

Woods, Carol M.; Grimm, Kevin J.

2011-01-01

In extant literature, multiple indicator multiple cause (MIMIC) models have been presented for identifying items that display uniform differential item functioning (DIF) only, not nonuniform DIF. This article addresses, for apparently the first time, the use of MIMIC models for testing both uniform and nonuniform DIF with categorical indicators. A…

Microwave interaction with nonuniform hydrogen gas in carbon nanotubes

International Nuclear Information System (INIS)

Babaei, S.; Babaei, Sh.

2009-01-01

In this paper we study the reflection, absorption, and transmission of microwave from nonuniform hydrogen gas in carbon nanotubes, grown by iron-catalyzed high-pressure carbon monoxide disproportionate (HiPco) process. A discussion on the effect of various hydrogen gas parameters on the reflected power, absorbed power, and transmitted power is presented. The nonuniform hydrogen gas slab is modeled by a series of subslabs. The overall number density profile across the whole slab follows a parabolic function. The total reflected, absorbed, and transmitted powers are then deduced and their functional dependence on the number density, collision frequency, and angle of propagation is studied

Stochastic Differential Equation Models for the Price of European CO2 Emissions Allowances

Directory of Open Access Journals (Sweden)

Wugan Cai

2017-02-01

Full Text Available Understanding the stochastic nature of emissions allowances is crucial for risk management in emissions trading markets. In this study, we discuss the emissions allowances spot price within the European Union Emissions Trading Scheme: Powernext and European Climate Exchange. To compare the fitness of five stochastic differential equations (SDEs to the European Union allowances spot price, we apply regression theory to obtain the point and interval estimations for the parameters of the SDEs. An empirical evaluation demonstrates that the mean reverting square root process (MRSRP has the best fitness of five SDEs to forecast the spot price. To reduce the degree of smog, we develop a new trading scheme in which firms have to hand many more allowances to the government when they emit one unit of air pollution on heavy pollution days, versus one allowance on clean days. Thus, we set up the SDE MRSRP model with Markovian switching to analyse the evolution of the spot price in such a scheme. The analysis shows that the allowances spot price will not jump too much in the new scheme. The findings of this study could contribute to developing a new type of emissions trading.

Characterization and Processing of Non-Uniformities in Back-Illuminated CCDs

Science.gov (United States)

Lemm, Alia D.; Della-Rose, Devin J.; Maddocks, Sally

2018-01-01

In astronomical photometry, Charged Coupled Device (CCD) detectors are used to achieve high precision photometry and must be properly calibrated to correct for noise and pixel non-uniformities. Uncalibrated images may contain bias offset, dark current, bias structure and uneven illumination. In addition, standard data reduction is often not sufficient to “normalize” imagery to single-digit millimagnitude (mmag) precision. We are investigating an apparent non-uniformity, or interference pattern, in a back-illuminated sensor, the Alta U-47, attached to a DFM Engineering 41-cm Ritchey-Chrétien f/8 telescope. Based on the amplitude of this effect, we estimate that instrument magnitude peak-to-valley deviations of 50 mmag or more may result. Our initial testing strongly suggests that reflected skylight from high pressure sodium city lights may be the cause of this interference pattern. Our research goals are twofold: to fully characterize this non-uniformity and to determine the best method to remove this interference pattern from our reduced CCD images.

Weighted backprojection implemented with a non-uniform attenuation map for improved SPECT quantitation

International Nuclear Information System (INIS)

Manglos, S.H.; Jaszczak, R.J.; Floyd, C.E.

1988-01-01

A method is developed to improve quantitation in SPECT imaging by using an attenuation compensation method which includes the correct non-uniform attenuation spatial distribution (''map''). The method is based on the technique of weighted back projection, previously developed for uniform attenuation. The method is tested by imaging a non-uniform phantom, reconstructing with the known attenuation map, and quantitatively comparing the resultant image with the known activity distribution. Reconstructed image profiles are dramatically improved in comparison to reconstructions without compensation or with an assumed uniform attenuation map. Contrast measurements further quantify the improvement. Line spread function distortions seen previously in non-uniform geometries are essentially eliminated by the method. Therefore, the method appears to be appropriate for these geometries, if the non-uniform map can be determined. Some additional image distortions introduced by the compensation method are noted and will require further study

The Effects of Nonuniform Illumination on the Electrical Performance of a Single Conventional Photovoltaic Cell

Directory of Open Access Journals (Sweden)

Damasen Ikwaba Paul

2015-01-01

Full Text Available Photovoltaic (PV concentrators are a promising approach for lowering PV electricity costs in the near future. However, most of the concentrators that are currently used for PV applications yield nonuniform flux profiles on the surface of a PV module which in turn reduces its electrical performance if the cells are serially connected. One way of overcoming this effect is the use of PV modules with isolated cells so that each cell generates current that is proportional to the energy flux absorbed. However, there are some cases where nonuniform illumination also exists in a single cell in an isolated cells PV module. This paper systematically studied the effect of nonuniform illumination on various cell performance parameters of a single monocrystalline standard PV cell at low and medium energy concentration ratios. Furthermore, the effect of orientation, size, and geometrical shapes of nonuniform illumination was also investigated. It was found that the effect of nonuniform illumination on various PV cell performance parameters of a single standard PV cell becomes noticeable at medium energy flux concentration whilst the location, size, and geometrical shape of nonuniform illumination have no effect on the performance parameters of the cell.

ACCOUNTING FOR GREENHOUSE GASES EMISSIONS ALLOWANCES IN ROMANIA

Directory of Open Access Journals (Sweden)

Marius Deac

2013-02-01

Full Text Available The present paper tries to analyze the accounting challenges that the implementation of EU Emissions Trading Scheme has risen. On 2 December 2004, IASB has issued an interpretation regarding the accounting of the GHG emissions allowances (IFRIC 3 „Emission Rights”. This interpretation should have been effective for annual periods beginning after 1 March 2005, the first year of the EU Emission Trading Scheme implementation. Less than a year after it was issued, IFRIC has withdrawn IFRIC 3. In December 2007, IASB has started a new project in order to provide guidance on accounting for carbon allowances called Emissions Trading Schemes Project. In the absence of an accounting standard regarding the accounting of these emissions allowances a diversity of accounting practices have been identified. Nowadays, there are three main accounting practices for the recognition of the emissions allowances and the GHG emissions liabilities: IFRIC 3 approach, the government grants approach and the net liability or off balance sheet approach. The accounting treatment of greenhouse gas emissions allowances by Romanian companies resembles the net liability or off balance sheet approach. Finance Ministry Order no. 1118/2012 states that GHG emission certificates should be recognized as fixed assets (if the entity is expecting a profit in the long term or in the category of short term investments (if the entity is expecting a profit in the short term. The accounting of the greenhouse gas emissions allowances described above is applicable mainly to traders of such certificates and not for the installations in the scope of the EU ETS directive, which should recognize GHG emissions off balance sheet, at their nominal value (nil if received for free. The shortfall or excess of allowances will be recognized in the profit or loss as they are bought or sold by the entity (the accounting treatment imposed by Finance Ministry Order no. 3055/2009.

Investigation of the influence of sampling schemes on quantitative dynamic fluorescence imaging.

Science.gov (United States)

Dai, Yunpeng; Chen, Xueli; Yin, Jipeng; Wang, Guodong; Wang, Bo; Zhan, Yonghua; Nie, Yongzhan; Wu, Kaichun; Liang, Jimin

2018-04-01

Dynamic optical data from a series of sampling intervals can be used for quantitative analysis to obtain meaningful kinetic parameters of probe in vivo . The sampling schemes may affect the quantification results of dynamic fluorescence imaging. Here, we investigate the influence of different sampling schemes on the quantification of binding potential ( BP ) with theoretically simulated and experimentally measured data. Three groups of sampling schemes are investigated including the sampling starting point, sampling sparsity, and sampling uniformity. In the investigation of the influence of the sampling starting point, we further summarize two cases by considering the missing timing sequence between the probe injection and sampling starting time. Results show that the mean value of BP exhibits an obvious growth trend with an increase in the delay of the sampling starting point, and has a strong correlation with the sampling sparsity. The growth trend is much more obvious if throwing the missing timing sequence. The standard deviation of BP is inversely related to the sampling sparsity, and independent of the sampling uniformity and the delay of sampling starting time. Moreover, the mean value of BP obtained by uniform sampling is significantly higher than that by using the non-uniform sampling. Our results collectively suggest that a suitable sampling scheme can help compartmental modeling of dynamic fluorescence imaging provide more accurate results and simpler operations.

Experimental and theoretical studies of the effects of nonuniformities in equilibrium MHD generators

International Nuclear Information System (INIS)

Rosenbaum, M.; Shamma, S.E.; Louis, J.F.

1980-01-01

An experimental study of the effects of thermal and velocity nonuniformities is performed in an equilibrium plasma for a range of Hall parameters. An electrodeless MHD disk generator with radial flow is chosen as the ideal geometry for these experiments. By introducing equally spaced cold blades in the flow, it is possible to create well defined two-dimensional wake nonuniformities with strong variations of the plasma properties in the direction normal to the magnetic field and the flow. This type of nonuniformity is predicted to provide the strongest reduction of Hall coefficient and effective conductivity for high values of Hall parameter. This degradation is controlled by both the level of nonuniformities and the value of the ideal Hall parameter. The former is dependent upon the number of blades (root mean square deviation of the conductivity), and the latter is dependent upon the values of the magnetic field intensities. The results provide basic quantitative information about the effects of conductivity and velocity nonuniformities on the performance of equilibrium MHD generators over a wide range of Hall coefficients, between 2 and 7. Reduction formulae are established between the effective and ideal Hall parameters for different levels of nonuniformities intensities. Theoretical predictions are derived from a detailed two-dimensional electrodynamic analysis and a simplified engineering model based on a generalization of Rosa's layer model. These experiments validate the analytical studies and support the use of the theoretical layer models in describing the effect of boundary layers on the performance of linear generators

Fluxon dynamics in long Josephson junctions in the presence of a temperature gradient or spatial nonuniformity

DEFF Research Database (Denmark)

Krasnov, V.M.; Oboznov, V.A.; Pedersen, Niels Falsig

1997-01-01

Fluxon dynamics in nonuniform Josephson junctions was studied both experimentally and theoretically. Two types of nonuniform junctions were considered: the first type had a nonuniform spatial distribution of critical and bias currents and the second had a temperature gradient applied along...... the junction. An analytical expression for the I-V curve in the presence of a temperature gradient or spatial nonuniformity was derived. It was shown that there is no static thermomagnetic Nernst effect due to Josephson fluxon motion despite the existence of a force pushing fluxons in the direction of smaller...

Analytical modeling of large amplitude free vibration of non-uniform beams carrying a both transversely and axially eccentric tip mass

Science.gov (United States)

Malaeke, Hasan; Moeenfard, Hamid

2016-03-01

The objective of this paper is to study large amplitude flexural-extensional free vibration of non-uniform cantilever beams carrying a both transversely and axially eccentric tip mass. The effects of variable axial force is also taken into account. Hamilton's principle is utilized to obtain the partial differential equations governing the nonlinear vibration of the system as well as the corresponding boundary conditions. A numerical finite difference scheme is proposed to find the natural frequencies and mode shapes of the system which is validated specifically for a beam with linearly varying cross section. Using a single mode approximation in conjunction with the Lagrange method, the governing equations are reduced to a set of two nonlinear ordinary differential equations in terms of end displacement components of the beam which are coupled due to the presence of the transverse eccentricity. These temporal coupled equations are then solved analytically using the multiple time scales perturbation technique. The obtained analytical results are compared with the numerical ones and excellent agreement is observed. The qualitative and quantitative knowledge resulting from this research is expected to enable the study of the effects of eccentric tip mass and non-uniformity on the large amplitude flexural-extensional vibration of beams for improved dynamic performance.

Radio-frequency properties of stacked long Josephson junctions with nonuniform bias current distribution

DEFF Research Database (Denmark)

Filatrella, G; Pedersen, Niels Falsig

1999-01-01

We have numerically investigated the behavior of stacks of long Josephson junctions considering a nonuniform bias profile. In the presence of a microwave field the nonuniform bias, which favors the formation of fluxons, can give rise to a change of the sequence of radio-frequency induced steps...

Instruction sequences and non-uniform complexity theory

NARCIS (Netherlands)

Bergstra, J.A.; Middelburg, C.A.

2008-01-01

We develop theory concerning non-uniform complexity in a setting in which the notion of single-pass instruction sequence considered in program algebra is the central notion. We define counterparts of the complexity classes P/poly and NP/poly and formulate a counterpart of the complexity theoretic

Derivation of nonlinear wave equations for ultrasound beam in nonuniform bubbly liquids

Science.gov (United States)

Kanagawa, Tetsuya; Yano, Takeru; Kawahara, Junya; Kobayashi, Kazumichi; Watanabe, Masao; Fujikawa, Shigeo

2012-09-01

Weakly nonlinear propagation of diffracted ultrasound beams in a nonuniform bubbly liquid is theoretically studied based on the method of multiple scales with the set of scaling relations of some physical parameters. It is assumed that the spatial distribution of the number density of bubbles in an initial state at rest is a slowly varying function of space coordinates and the amplitude of its variation is small compared with a mean number density. As a result, a Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation with dispersion and nonuniform effects for a low frequency case and a nonlinear Schrödinger (NLS) equation with dissipation, diffraction, and nonuniform effects for a high frequency case, are derived from the basic equations of bubbly flows.

Cryo-EM image alignment based on nonuniform fast Fourier transform

International Nuclear Information System (INIS)

Yang Zhengfan; Penczek, Pawel A.

2008-01-01

In single particle analysis, two-dimensional (2-D) alignment is a fundamental step intended to put into register various particle projections of biological macromolecules collected at the electron microscope. The efficiency and quality of three-dimensional (3-D) structure reconstruction largely depends on the computational speed and alignment accuracy of this crucial step. In order to improve the performance of alignment, we introduce a new method that takes advantage of the highly accurate interpolation scheme based on the gridding method, a version of the nonuniform fast Fourier transform, and utilizes a multi-dimensional optimization algorithm for the refinement of the orientation parameters. Using simulated data, we demonstrate that by using less than half of the sample points and taking twice the runtime, our new 2-D alignment method achieves dramatically better alignment accuracy than that based on quadratic interpolation. We also apply our method to image to volume registration, the key step in the single particle EM structure refinement protocol. We find that in this case the accuracy of the method not only surpasses the accuracy of the commonly used real-space implementation, but results are achieved in much shorter time, making gridding-based alignment a perfect candidate for efficient structure determination in single particle analysis

Cryo-EM image alignment based on nonuniform fast Fourier transform.

Science.gov (United States)

Yang, Zhengfan; Penczek, Pawel A

2008-08-01

In single particle analysis, two-dimensional (2-D) alignment is a fundamental step intended to put into register various particle projections of biological macromolecules collected at the electron microscope. The efficiency and quality of three-dimensional (3-D) structure reconstruction largely depends on the computational speed and alignment accuracy of this crucial step. In order to improve the performance of alignment, we introduce a new method that takes advantage of the highly accurate interpolation scheme based on the gridding method, a version of the nonuniform fast Fourier transform, and utilizes a multi-dimensional optimization algorithm for the refinement of the orientation parameters. Using simulated data, we demonstrate that by using less than half of the sample points and taking twice the runtime, our new 2-D alignment method achieves dramatically better alignment accuracy than that based on quadratic interpolation. We also apply our method to image to volume registration, the key step in the single particle EM structure refinement protocol. We find that in this case the accuracy of the method not only surpasses the accuracy of the commonly used real-space implementation, but results are achieved in much shorter time, making gridding-based alignment a perfect candidate for efficient structure determination in single particle analysis.

Casimir energy of a nonuniform string

Science.gov (United States)

Hadasz, L.; Lambiase, G.; Nesterenko, V. V.

2000-07-01

The Casimir energy of a nonuniform string built up from two pieces with different speeds of sound is calculated. A standard procedure of subtracting the energy of an infinite uniform string is applied, the subtraction being interpreted as the renormalization of the string tension. It is shown that in the case of a homogeneous string this method is completely equivalent to zeta renormalization.

Verifiable Secret Redistribution for Threshold Sharing Schemes

National Research Council Canada - National Science Library

Wong, Theodore M; Wang, Chenxi; Wing, Jeannette M

2002-01-01

.... Our protocol guards against dynamic adversaries. We observe that existing protocols either cannot be readily extended to allow redistribution between different threshold schemes, or have vulnerabilities that allow faulty old shareholders...

The Superconvergence Phenomenon and Proof of the MAC Scheme for the Stokes Equations on Non-uniform Rectangular Meshes

KAUST Repository

Li, Jichun; Sun, Shuyu

2014-01-01

For decades, the widely used finite difference method on staggered grids, also known as the marker and cell (MAC) method, has been one of the simplest and most effective numerical schemes for solving the Stokes equations and Navier–Stokes equations

Outer region scaling using the freestream velocity for nonuniform open channel flow over gravel

Science.gov (United States)

Stewart, Robert L.; Fox, James F.

2017-06-01

The theoretical basis for outer region scaling using the freestream velocity for nonuniform open channel flows over gravel is derived and tested for the first time. Owing to the gradual expansion of the flow within the nonuniform case presented, it is hypothesized that the flow can be defined as an equilibrium turbulent boundary layer using the asymptotic invariance principle. The hypothesis is supported using similarity analysis to derive a solution, followed by further testing with experimental datasets. For the latter, 38 newly collected experimental velocity profiles across three nonuniform flows over gravel in a hydraulic flume are tested as are 43 velocity profiles previously published in seven peer-reviewed journal papers that focused on fluid mechanics of nonuniform open channel over gravel. The findings support the nonuniform flows as equilibrium defined by the asymptotic invariance principle, which is reflective of the consistency of the turbulent structure's form and function within the expanding flow. However, roughness impacts the flow structure when comparing across the published experimental datasets. As a secondary objective, we show how previously published mixed scales can be used to assist with freestream velocity scaling of the velocity deficit and thus empirically account for the roughness effects that extend into the outer region of the flow. One broader finding of this study is providing the theoretical context to relax the use of the elusive friction velocity when scaling nonuniform flows in gravel bed rivers; and instead to apply the freestream velocity. A second broader finding highlighted by our results is that scaling of nonuniform flow in gravel bed rivers is still not fully resolved theoretically since mixed scaling relies to some degree on empiricism. As researchers resolve the form and function of macroturbulence in the outer region, we hope to see the closing of this research gap.

Non-uniform Mutation Rates for Problems with Unknown Solution Lengths

DEFF Research Database (Denmark)

Cathabard, Stephan; Lehre, Per Kristian; Yao, Xin

2011-01-01

Many practical optimisation problems allow candidate solu- tions of varying lengths, and where the length of the opti- mal solution is thereby a priori unknown. We suggest that non-uniform mutation rates can be beneficial when solving such problems. In particular, we consider a mutation oper- ator...... that flips each bit with a probability that is inversely proportional to the bit position, rather than the bitstring length. The runtime of the (1+1) EA using this mutation operator is analysed rigorously on standard example func- tions. Furthermore, the behaviour of the new mutation op- erator...... distribution, and show that the new operator can yield exponentially faster runtimes for some parameters of this distribution. The experimental results show that the new mutation operator leads to dramatically shorter runtimes on a class of instances of the software engi- neering problem that is conjectured...

Joint de-blurring and nonuniformity correction method for infrared microscopy imaging

Science.gov (United States)

Jara, Anselmo; Torres, Sergio; Machuca, Guillermo; Ramírez, Wagner; Gutiérrez, Pablo A.; Viafora, Laura A.; Godoy, Sebastián E.; Vera, Esteban

2018-05-01

In this work, we present a new technique to simultaneously reduce two major degradation artifacts found in mid-wavelength infrared microscopy imagery, namely the inherent focal-plane array nonuniformity noise and the scene defocus presented due to the point spread function of the infrared microscope. We correct both nuisances using a novel, recursive method that combines the constant range nonuniformity correction algorithm with a frame-by-frame deconvolution approach. The ability of the method to jointly compensate for both nonuniformity noise and blur is demonstrated using two different real mid-wavelength infrared microscopic video sequences, which were captured from two microscopic living organisms using a Janos-Sofradir mid-wavelength infrared microscopy setup. The performance of the proposed method is assessed on real and simulated infrared data by computing the root mean-square error and the roughness-laplacian pattern index, which was specifically developed for the present work.

Investigation of Non-Uniform Rust Distribution and Its Effects on Corrosion Induced Cracking in Reinforced Concrete

Directory of Open Access Journals (Sweden)

Sutrisno Wahyuniarsih

2017-01-01

Full Text Available Uniform corrosion still widely used by a lot of researchers and engineers to analyze the corrosion induced cracking. However, in practice, corrosion process occurred non-uniformly. The part nearest to the exposed surface is more likely to have faster corrosion initiation compared with other regions. This research is mainly focused on investigating the effect of non-uniform rust distribution to cover cracking in reinforced concrete. An experimental test performed using accelerated corrosion test by using 5% NaCl solution and applied a constant electric current to the concrete samples. The rust distribution and measurement were observed by using a digital microscope. Based on the experimental result, it was found that the rust was distributed in a non-uniform pattern. As a result, the cracks also formed non-uniformly along the perimeter of steel bar. At the last part of this paper, a simulation result of concrete cracking induced by non-uniform corrosion is presented. The result compared with a simulation using uniform corrosion assumption to investigate the damage pattern of each model. The simulation result reveals stress evolution due to rust expansion which leads to concrete cracking. Furthermore, a comparison of stresses induced by non-uniform corrosion and uniform corrosion indicates that non-uniform corrosion could lead to earlier damage to the structure which is specified by the formation and propagation of the crack.

Asynchronous discrete event schemes for PDEs

Science.gov (United States)

Stone, D.; Geiger, S.; Lord, G. J.

2017-08-01

A new class of asynchronous discrete-event simulation schemes for advection-diffusion-reaction equations is introduced, based on the principle of allowing quanta of mass to pass through faces of a (regular, structured) Cartesian finite volume grid. The timescales of these events are linked to the flux on the face. The resulting schemes are self-adaptive, and local in both time and space. Experiments are performed on realistic physical systems related to porous media flow applications, including a large 3D advection diffusion equation and advection diffusion reaction systems. The results are compared to highly accurate reference solutions where the temporal evolution is computed with exponential integrator schemes using the same finite volume discretisation. This allows a reliable estimation of the solution error. Our results indicate a first order convergence of the error as a control parameter is decreased, and we outline a framework for analysis.

Computer Simulation of Nonuniform MTLs via Implicit Wendroff and State-Variable Methods

Directory of Open Access Journals (Sweden)

L. Brancik

2011-04-01

Full Text Available The paper deals with techniques for a computer simulation of nonuniform multiconductor transmission lines (MTLs based on the implicit Wendroff and the statevariable methods. The techniques fall into a class of finitedifference time-domain (FDTD methods useful to solve various electromagnetic systems. Their basic variants are extended and modified to enable solving both voltage and current distributions along nonuniform MTL’s wires and their sensitivities with respect to lumped and distributed parameters. An experimental error analysis is performed based on the Thomson cable whose analytical solutions are known, and some examples of simulation of both uniform and nonuniform MTLs are presented. Based on the Matlab language programme, CPU times are analyzed to compare efficiency of the methods. Some results for nonlinear MTLs simulation are presented as well.

Circumferential nonuniformity of cladding radiation swelling of fast reactor peripheral fuel elements

International Nuclear Information System (INIS)

Reutov, V.F.; Farkhutdinov, K.G.

1977-01-01

The results are presented of the investigation into the perimeter radiation swelling of Kh18N10T stainless steel cladding in different cross sections of a peripheral fuel element of the BR-5 reactor. The fluence on the cladding is 1.8-2.9 x 10 22 fast neutr/cm 2 , the operating temperatures in different parts of the fuel element being 430 deg to 585 deg C. There has been observed circumferential non-uniformity of the distribution, concentration, and of the total volume of radiation cavities, which is due to temperature non-uniformity along the cladding perimeter. It is shown that such non-uniformity of radiation swelling of the cladding material may result in bending of the peripheral fuel element with regard to the fuel assembly sheath walls

Photocathode non-uniformity contribution to the energy resolution of scintillators

International Nuclear Information System (INIS)

Mottaghian, M.; Koohi-Fayegh, R.; Ghal-Eh, N.; Etaati, G. R.

2010-01-01

This paper introduces the basics of the light transport simulation in scintillators and the wavelength-dependencies in the process. The non-uniformity measurement of the photocathode surface is undertaken, showing that for the photocathode used in this study the quantum efficiency falls to about 4% of its maximum value, especially in areas far from the centre. The wavelength-and position-dependent quantum efficiency is implemented in the Monte Carlo light transport code, showing that, the contribution of the photocathode non-uniformity to the energy resolution is estimated to be around 18%, when all position-and wavelength-dependencies are included. (authors)

A repeat-until-success quantum computing scheme

Energy Technology Data Exchange (ETDEWEB)

Beige, A [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Lim, Y L [DSO National Laboratories, 20 Science Park Drive, Singapore 118230, Singapore (Singapore); Kwek, L C [Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore (Singapore)

2007-06-15

Recently we proposed a hybrid architecture for quantum computing based on stationary and flying qubits: the repeat-until-success (RUS) quantum computing scheme. The scheme is largely implementation independent. Despite the incompleteness theorem for optical Bell-state measurements in any linear optics set-up, it allows for the implementation of a deterministic entangling gate between distant qubits. Here we review this distributed quantum computation scheme, which is ideally suited for integrated quantum computation and communication purposes.

A repeat-until-success quantum computing scheme

International Nuclear Information System (INIS)

Beige, A; Lim, Y L; Kwek, L C

2007-01-01

Recently we proposed a hybrid architecture for quantum computing based on stationary and flying qubits: the repeat-until-success (RUS) quantum computing scheme. The scheme is largely implementation independent. Despite the incompleteness theorem for optical Bell-state measurements in any linear optics set-up, it allows for the implementation of a deterministic entangling gate between distant qubits. Here we review this distributed quantum computation scheme, which is ideally suited for integrated quantum computation and communication purposes

A poloidal non-uniformity of the collisionless parallel current in a tokamak plasma

Energy Technology Data Exchange (ETDEWEB)

Romannikov, A.; Fenzi-Bonizec, C

2005-07-01

The collisionless distortion of the ion (electron) distribution function at certain points on a magnetic surface is studied in the framework of a simple model of a large aspect ratio tokamak plasma. The flow velocity driven by this distortion is calculated. The possibility of an additional non-uniform collisionless parallel current density on a magnetic surface, other than the known neo-classical non-uniformity is shown. The difference between the parallel current density on the low and high field side of a magnetic surface is close to the neoclassical bootstrap current density. The first Tore-Supra experimental test indicates the possibility of the poloidal non-uniformity of the parallel current density. (authors)

Emittance growth caused by nonuniform charge distribution of bunched beam in linac

International Nuclear Information System (INIS)

Chen Yinbao; Zhang Zhenhai

1993-09-01

The nonlinear space charge effect of bunched beam in linac is one of the important reasons that induces the emittance growth because of the conversion of the field energy to kinetic energy. The authors have worked out the internal field energies associated with some nonuniform space change distributions of a bunched beam, such as Gaussian distribution, waterbag distribution and parabolic distribution. And the emittance growths caused by these nonuniformities are obtained

Effects of non-uniform core flow on peak cladding temperature: MOXY/SCORE sensitivity calculations

Energy Technology Data Exchange (ETDEWEB)

Chang, S.C.

1979-08-15

The MOXY/SCORE computer program is used to evaluate the potential effect on peak cladding temperature of selective cooling that may result from a nonuniform mass flux at the core boundaries during the blowdown phase of the LOFT L2-4 test. The results of this study indicate that the effect of the flow nonuniformity at the core boundaries will be neutralized by a strong radial flow redistribution in the neighborhood of core boundaries. The implication is that the flow nonuniformity at the core boundaries has no significant effect on the thermal-hydraulic behavior and cladding temperature at the hot plane.

Effects of non-uniform core flow on peak cladding temperature: MOXY/SCORE sensitivity calculations

International Nuclear Information System (INIS)

Chang, S.C.

1979-01-01

The MOXY/SCORE computer program is used to evaluate the potential effect on peak cladding temperature of selective cooling that may result from a nonuniform mass flux at the core boundaries during the blowdown phase of the LOFT L2-4 test. The results of this study indicate that the effect of the flow nonuniformity at the core boundaries will be neutralized by a strong radial flow redistribution in the neighborhood of core boundaries. The implication is that the flow nonuniformity at the core boundaries has no significant effect on the thermal-hydraulic behavior and cladding temperature at the hot plane

Wastewater diffusive dilution and sedimentation of the fine contaminated particles for nonuniform flow in open channels

Directory of Open Access Journals (Sweden)

Lyapin Anton

2018-01-01

Full Text Available The influence of non-uniformity on mass transfer processes in open channels have been investigated under the action of urbanization factors. The study is related to the urgent problem of environmental degradation of water objects in urbanized areas. It is known that the water quality in the water objects depends on the manner in which the contaminants spread how they mix with the river water and diluted by it. The main results of the study consist of recommendations to incorporate non-uniformity factor to the calculation of diffusion dilution of wastewater and prediction of river processes. So the effect of the flow non-uniformity on the diffusion model of pollutants dilution and diffusion coefficient have been investigated. Formulas for the concentration profiles calculating and the average concentration of fine particulate matter in nonuniform gradually varied flow were presented. The deposition length of suspended contaminants were received, based on the hydraulic resistance laws of nonuniform gradually varied flow.

The Pierce diode with an external circuit: II, Non-uniform equilibria

International Nuclear Information System (INIS)

Lawson, W.S.

1987-01-01

The non-uniform (non-linear) equilibria of the classical (short circuit) Pierce diode and the extended (series RLC external circuit) Pierce diode are described theoretically, and explored via computer simulation. It is found that most equilibria are correctly predicted by theory, but that the continuous set of equilibria of the classical Pierce diode at α = 2π are not observed. The stability characteristics of the non-uniform equilibria are also worked out, and are consistent with the simulations. 8 refs., 22 figs., 3 tabs

Nonuniform Illumination Correction Algorithm for Underwater Images Using Maximum Likelihood Estimation Method

Directory of Open Access Journals (Sweden)

Sonali Sachin Sankpal

2016-01-01

Full Text Available Scattering and absorption of light is main reason for limited visibility in water. The suspended particles and dissolved chemical compounds in water are also responsible for scattering and absorption of light in water. The limited visibility in water results in degradation of underwater images. The visibility can be increased by using artificial light source in underwater imaging system. But the artificial light illuminates the scene in a nonuniform fashion. It produces bright spot at the center with the dark region at surroundings. In some cases imaging system itself creates dark region in the image by producing shadow on the objects. The problem of nonuniform illumination is neglected by the researchers in most of the image enhancement techniques of underwater images. Also very few methods are discussed showing the results on color images. This paper suggests a method for nonuniform illumination correction for underwater images. The method assumes that natural underwater images are Rayleigh distributed. This paper used maximum likelihood estimation of scale parameter to map distribution of image to Rayleigh distribution. The method is compared with traditional methods for nonuniform illumination correction using no-reference image quality metrics like average luminance, average information entropy, normalized neighborhood function, average contrast, and comprehensive assessment function.

Nonuniform grid implicit spatial finite difference method for acoustic wave modeling in tilted transversely isotropic media

KAUST Repository

Chu, Chunlei

2012-01-01

Discrete earth models are commonly represented by uniform structured grids. In order to ensure accurate numerical description of all wave components propagating through these uniform grids, the grid size must be determined by the slowest velocity of the entire model. Consequently, high velocity areas are always oversampled, which inevitably increases the computational cost. A practical solution to this problem is to use nonuniform grids. We propose a nonuniform grid implicit spatial finite difference method which utilizes nonuniform grids to obtain high efficiency and relies on implicit operators to achieve high accuracy. We present a simple way of deriving implicit finite difference operators of arbitrary stencil widths on general nonuniform grids for the first and second derivatives and, as a demonstration example, apply these operators to the pseudo-acoustic wave equation in tilted transversely isotropic (TTI) media. We propose an efficient gridding algorithm that can be used to convert uniformly sampled models onto vertically nonuniform grids. We use a 2D TTI salt model to demonstrate its effectiveness and show that the nonuniform grid implicit spatial finite difference method can produce highly accurate seismic modeling results with enhanced efficiency, compared to uniform grid explicit finite difference implementations. © 2011 Elsevier B.V.

A simple smoothness indicator for the WENO scheme with adaptive order

Science.gov (United States)

Huang, Cong; Chen, Li Li

2018-01-01

The fifth order WENO scheme with adaptive order is competent for solving hyperbolic conservation laws, its reconstruction is a convex combination of a fifth order linear reconstruction and three third order linear reconstructions. Note that, on uniform mesh, the computational cost of smoothness indicator for fifth order linear reconstruction is comparable with the sum of ones for three third order linear reconstructions, thus it is too heavy; on non-uniform mesh, the explicit form of smoothness indicator for fifth order linear reconstruction is difficult to be obtained, and its computational cost is much heavier than the one on uniform mesh. In order to overcome these problems, a simple smoothness indicator for fifth order linear reconstruction is proposed in this paper.

Modeling of nonuniform corrosion in salt brines: Salt Repository Project

International Nuclear Information System (INIS)

Reimus, P.W.

1988-03-01

A mechanistic approach to modeling nonuniform corrosion in brines is presented in this report. Equations are derived for completely describing the electrochemical environment within a localized corrosion cavity, and appropriate initial and boundary conditions are invoked to obtain a solvable system of equations. The initial and boundary conditions can be adjusted to simulate pitting, crevice corrosion, or stress corrosion cracking. Although no numerical results are presented, a numerical strategy for solving the equations is presented. The report focuses on the nonuniform corrosion behavior of mild steel; however, the modeling approach presented is expected to apply to a broad range of metallic materials. 34 refs., 5 figs., 2 tabs

Vibration of nonuniform carbon nanotube with attached mass via nonlocal Timoshenko beam theory

International Nuclear Information System (INIS)

Tang, Hai Li; Shen, Zhi Bin; Li, Dao Kui

2014-01-01

This paper studies the vibrational behavior of nonuniform single-walled carbon nanotube (SWCNT) carrying a nanoparticle. A nonuniform cantilever beam with a concentrated mass at the free end is analyzed according to the nonlocal Timoshenko beam theory. A governing equation of a nonuniform SWCNT with attached mass is established. The transfer function method incorporating with the perturbation method is utilized to obtain the resonant frequencies of a vibrating nonlocal cantilever-mass system. The effects of the nonlocal parameter, taper ratio and attached mass on the natural frequencies and frequency shifts are discussed. Obtained results indicate that the sensitivity of the frequency shifts on the attached mass increases when the length-to-diameter ratio decreases. Tapered SWCNT possesses higher fundamental frequencies if the taper ratio becomes larger.

An Investigation into Conversion from Non-Uniform Rational B-Spline Boundary Representation Geometry to Constructive Solid Geometry

Science.gov (United States)

2015-12-01

ARL-SR-0347 ● DEC 2015 US Army Research Laboratory An Investigation into Conversion from Non-Uniform Rational B-Spline Boundary...US Army Research Laboratory An Investigation into Conversion from Non-Uniform Rational B-Spline Boundary Representation Geometry to...from Non-Uniform Rational B-Spline Boundary Representation Geometry to Constructive Solid Geometry 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

Improvement of a Privacy Authentication Scheme Based on Cloud for Medical Environment.

Science.gov (United States)

Chiou, Shin-Yan; Ying, Zhaoqin; Liu, Junqiang

2016-04-01

Medical systems allow patients to receive care at different hospitals. However, this entails considerable inconvenience through the need to transport patients and their medical records between hospitals. The development of Telecare Medicine Information Systems (TMIS) makes it easier for patients to seek medical treatment and to store and access medical records. However, medical data stored in TMIS is not encrypted, leaving patients' private data vulnerable to external leaks. In 2014, scholars proposed a new cloud-based medical information model and authentication scheme which would not only allow patients to remotely access medical services but also protects patient privacy. However, this scheme still fails to provide patient anonymity and message authentication. Furthermore, this scheme only stores patient medical data, without allowing patients to directly access medical advice. Therefore, we propose a new authentication scheme, which provides anonymity, unlinkability, and message authentication, and allows patients to directly and remotely consult with doctors. In addition, our proposed scheme is more efficient in terms of computation cost. The proposed system was implemented in Android system to demonstrate its workability.

The magneto-optical properties of non-uniform graphene nanoribbons

Science.gov (United States)

Chung, Hsien-Ching; Lin, Ming-Fa

2015-03-01

When synthesizing few-layer graphene nanoribbons (GNRs), non-uniform GNRs would be made simultaneously. Recently, the non-uniform GNRs, which is a stack of two GNRs with unequal widths, have been fabricated by mechanically exfoliated from bulk graphite. Some theoretical predictions have been reported, such as gap opening and transport properties. Under the influence of magnetic fields, magnetic quantization takes place and drastically changes the electronic properties. By tuning the geometric configuration, four categories of magneto-electronic spectra are exhibited. (1) The spectrum is mostly contributed by quasi-Landau levels (QLLs) of monolayer GNRs. (2) The spectrum displays two groups of QLLs, and the non-uniform GNR behaves like a bilayer one. (3) An intermediate category, the spectrum is composite disordered. (4) The spectrum presents the coexistence of monolayer and bilayer spectra. In this work, the magneto-electronic and optical properties for different geometric configurations are given, such as energy dispersions, density of states, wave functions, and magneto-absorption spectra are presented. Furthermore, the transformation between monolayer and bilayer spectra as well as the coexistence of monolayer and bilayer spectra are discussed in detail. One of us (Hsien-Ching Chung) thanks Ming-Hui Chung and Su-Ming Chen for financial support. This work was supported in part by the National Science Council of Taiwan under Grant Number 98-2112-M-006-013-MY4.

Effects of Nonuniform Incident Illumination on the Thermal Performance of a Concentrating Triple Junction Solar Cell

Directory of Open Access Journals (Sweden)

Fahad Al-Amri

2014-01-01

Full Text Available A numerical heat transfer model was developed to investigate the temperature of a triple junction solar cell and the thermal characteristics of the airflow in a channel behind the solar cell assembly using nonuniform incident illumination. The effects of nonuniformity parameters, emissivity of the two channel walls, and Reynolds number were studied. The maximum solar cell temperature sharply increased in the presence of nonuniform light profiles, causing a drastic reduction in overall efficiency. This resulted in two possible solutions for solar cells to operate in optimum efficiency level: (i adding new receiver plate with higher surface area or (ii using forced cooling techniques to reduce the solar cell temperature. Thus, surface radiation exchanges inside the duct and Re significantly reduced the maximum solar cell temperature, but a conventional plain channel cooling system was inefficient for cooling the solar cell at medium concentrations when the system was subjected to a nonuniform light distribution. Nonuniformity of the incident light and surface radiation in the duct had negligible effects on the collected thermal energy.

Synergistic nonuniform shortening of atrial refractory period induced by autonomic stimulation.

Science.gov (United States)

Takei, M; Furukawa, Y; Narita, M; Ren, L M; Karasawa, Y; Murakami, M; Chiba, S

1991-12-01

We investigated the nonuniform effects of autonomic nerve stimulation of the effective refractory period (ERP) of the right atrium in the anesthetized dog. Stimulation of the discrete intracardiac sympathetic nerves to the sinoatrial (SA) nodal region uniformly shortened ERPs at three sites in the right atrium after administration of atropine. Right ansa subclavia (RS) stimulation similarly shortened ERPs in the absence of atropine. Stimulation of the discrete intracardiac parasympathetic nerves to the SA nodal region (SAP stimulation) shortened ERPs of the right atrium in a nonuniform manner. Simultaneous RS and SAP stimulation additively shortened ERPs at each site and decreased sinus rate much more than SAP stimulation alone. Shortening of ERP induced by SAP stimulation was greater than that induced by RS stimulation at similar absolute changes in heart rate. These results suggest that simultaneous activation of sympathetic and parasympathetic nerves nonuniformly shortens the ERP in the right atrium as the algebraic sum of the individual responses to each stimulation. However, parasympathetics exert the principal neural control over atrial ERP.

Formal Model of Certificate Omission Schemes in VANET

NARCIS (Netherlands)

Feiri, Michael; Petit, Jonathan; Kargl, Frank

2014-01-01

The benefits of certificate omission schemes in VANET have been so far proven by simulation. However, the research community is lacking of a formal model that would allow implementers and policy makers to select the optimal parameters for such schemes. In this paper, we lay the foundations of the

A nonuniform-polarization high-energy ultra-broadband laser with a long erbium-doped fiber

International Nuclear Information System (INIS)

Mao, Dong

2013-01-01

We have experimentally investigated nonuniformly polarized broadband high-energy pulses delivered from a mode-locked laser with an ultra-long erbium-doped fiber (EDF). The pulses exhibit a broadband spectrum of ∼73 nm and can avoid optical wave breaking at high-pump regimes. The polarization states of the pulses evolve from uniform to nonuniform at each round trip in the oscillator, which is distinct from other pulses. Remarkably, the output pulses broaden in anomalous- or normal-dispersion regimes while they can be shortened with an EDF amplifier external to the cavity. Our results suggest that the long EDF results in a nonuniform-polarization state and plays a decisive role in the formation of high-energy pulses. (paper)

Josephson flux-flow oscillators in nonuniform microwave fields

DEFF Research Database (Denmark)

Salerno, Mario; Samuelsen, Mogens Rugholm

2000-01-01

We present a simple theory for Josephson flux-flow oscillators in the presence of nonuniform microwave fields. In particular we derive an analytical expression for the I-V characteristic of the oscillator from which we show that satellite steps are spaced around the main flux-flow resonance by only...

Absolute parametric instability in a nonuniform plane plasma

Indian Academy of Sciences (India)

The paper reports an analysis of the effect of spatial plasma nonuniformity on absolute parametric instability (API) of electrostatic waves in magnetized plane waveguides subjected to an intense high-frequency (HF) electric field using the separation method. In this case the effect of strong static magnetic field is considered.

Nested Hilbert schemes on surfaces: Virtual fundamental class

DEFF Research Database (Denmark)

Gholampour, Amin; Sheshmani, Artan; Yau, Shing-Tung

We construct natural virtual fundamental classes for nested Hilbert schemes on a nonsingular projective surface S. This allows us to define new invariants of S that recover some of the known important cases such as Poincare invariants of Durr-Kabanov-Okonek and the stable pair invariants of Kool......-Thomas. In the case of the nested Hilbert scheme of points, we can express these invariants in terms of integrals over the products of Hilbert scheme of points on S, and relate them to the vertex operator formulas found by Carlsson-Okounkov. The virtual fundamental classes of the nested Hilbert schemes play a crucial...

Thermal freeze-out and longitudinally non-uniform collective expansion flow in relativistic heavy ion collisions

CERN Document Server

Feng Sheng Qin; LianShouLiu

2002-01-01

The non-uniform longitudinal flow model (NUFM) proposed recently is extended to include also the transverse flow. The resulting longitudinally non-uniform collective expansion model (NUCEM) is applied to the calculation of rapidity distribution of kaons, lambdas and protons in relativistic heavy ion collisions at CERN-SPS energies. The model results are compared with the 200 A GeV/c S-S and 158 A GeV/c Pb-Pb collision data. The central dips observed in experiments are reproduced in a natural way. It is found that the depth of the central dip depends on the magnitude of the parameter e and the mass of produced particles, i.e. the non-uniformity of the longitudinal flow which is described by the parameter e determines the depth of the central dip for produced particles. Comparing with one-dimensional non-uniform longitudinal flow model, the rapidity distribution of lighter strange particle kaon also shows a dip due to the effect of transverse flow

Reaction schemes of immunoanalysis

International Nuclear Information System (INIS)

Delaage, M.; Barbet, J.

1991-01-01

The authors apply a general theory for multiple equilibria to the reaction schemes of immunoanalysis, competition and sandwich. This approach allows the manufacturer to optimize the system and provide the user with interpolation functions for the standard curve and its first derivative as well, thus giving access to variance [fr

An improved biometrics-based remote user authentication scheme with user anonymity.

Science.gov (United States)

Khan, Muhammad Khurram; Kumari, Saru

2013-01-01

The authors review the biometrics-based user authentication scheme proposed by An in 2012. The authors show that there exist loopholes in the scheme which are detrimental for its security. Therefore the authors propose an improved scheme eradicating the flaws of An's scheme. Then a detailed security analysis of the proposed scheme is presented followed by its efficiency comparison. The proposed scheme not only withstands security problems found in An's scheme but also provides some extra features with mere addition of only two hash operations. The proposed scheme allows user to freely change his password and also provides user anonymity with untraceability.

Research on Creep Relaxation Non-uniformity and Effect on Performance of Combined Rotor

Science.gov (United States)

Liu, Qingya; He, Jingfei; Zhao, Lijia

2017-11-01

The combined rotor of gas turbine is connected by a certain number of rod bolts. It works in the high temperature environment for a long time, and the rod bolts will creep and relax. Under the influence of elastic interaction, the loss of pretightening force of rod bolts at different positions is non-uniform, which will cause the connection of the combined rotor to be out of tune. In this paper, the creep relaxation non-uniformity model for a class F heavy duty gas turbine is established. On the basis of this, the performance degradation and structural strength change of combined rotor resulting from creep relaxation non-uniformity of rod bolts are studied. The results show that the ratio of preload mistuning increases with time and then converges, and there is a threshold inflection point in about seven thousand hours.

Proposal for a Domain Wall Nano-Oscillator driven by Non-uniform Spin Currents

Science.gov (United States)

Sharma, Sanchar; Muralidharan, Bhaskaran; Tulapurkar, Ashwin

2015-09-01

We propose a new mechanism and a related device concept for a robust, magnetic field tunable radio-frequency (rf) oscillator using the self oscillation of a magnetic domain wall subject to a uniform static magnetic field and a spatially non-uniform vertical dc spin current. The self oscillation of the domain wall is created as it translates periodically between two unstable positions, one being in the region where both the dc spin current and the magnetic field are present, and the other, being where only the magnetic field is present. The vertical dc spin current pushes it away from one unstable position while the magnetic field pushes it away from the other. We show that such oscillations are stable under noise and can exhibit a quality factor of over 1000. A domain wall under dynamic translation, not only being a source for rich physics, is also a promising candidate for advancements in nanoelectronics with the actively researched racetrack memory architecture, digital and analog switching paradigms as candidate examples. Devising a stable rf oscillator using a domain wall is hence another step towards the realization of an all domain wall logic scheme.

Nonquasineutral electron vortices in nonuniform plasmas

Energy Technology Data Exchange (ETDEWEB)

Angus, J. R.; Richardson, A. S.; Swanekamp, S. B.; Schumer, J. W. [Plasma Physics Division, Naval Research Laboratory, Washington, District of Columbia 20375 (United States); Ottinger, P. F. [Engility Corporation, Chantilly, Virginia 20151 (United States)

2014-11-15

Electron vortices are observed in the numerical simulation of current carrying plasmas on fast time scales where the ion motion can be ignored. In plasmas with nonuniform density n, vortices drift in the B × ∇n direction with a speed that is on the order of the Hall speed. This provides a mechanism for magnetic field penetration into a plasma. Here, we consider strong vortices with rotation speeds V{sub ϕ} close to the speed of light c where the vortex size δ is on the order of the magnetic Debye length λ{sub B}=|B|/4πen and the vortex is thus nonquasineutral. Drifting vortices are typically studied using the electron magnetohydrodynamic model (EMHD), which ignores the displacement current and assumes quasineutrality. However, these assumptions are not strictly valid for drifting vortices when δ ≈ λ{sub B}. In this paper, 2D electron vortices in nonuniform plasmas are studied for the first time using a fully electromagnetic, collisionless fluid code. Relatively large amplitude oscillations with periods that correspond to high frequency extraordinary modes are observed in the average drift speed. The drift speed W is calculated by averaging the electron velocity field over the vorticity. Interestingly, the time-averaged W from these simulations matches very well with W from the much simpler EMHD simulations even for strong vortices with order unity charge density separation.

Absolute parametric instability in a nonuniform plane plasma ...

Indian Academy of Sciences (India)

Abstract. The paper reports an analysis of the effect of spatial plasma nonuniformity on absolute parametric instability (API) of electrostatic waves in magnetized plane waveguides subjected to an intense high-frequency (HF) electric field using the separation method. In this case the effect of strong static magnetic field is ...

Nonuniform grid implicit spatial finite difference method for acoustic wave modeling in tilted transversely isotropic media

KAUST Repository

Chu, Chunlei; Stoffa, Paul L.

2012-01-01

sampled models onto vertically nonuniform grids. We use a 2D TTI salt model to demonstrate its effectiveness and show that the nonuniform grid implicit spatial finite difference method can produce highly accurate seismic modeling results with enhanced

Determination of non-uniformity correction factors for cylindrical ionization chambers close to 192Ir brachytherapy sources

International Nuclear Information System (INIS)

Toelli, H.; Bielajew, A. F.; Mattsson, O.; Sernbo, G.

1995-01-01

When ionization chambers are used in brachytherapy dosimetry, the measurements must be corrected for the non-uniformity of the incident photon fluence. The theory for determination of non-uniformity correction factors, developed by Kondo and Randolph (Rad. Res. 1960) assumes that the electron fluence within the air cavity is isotropic and does not take into account material differences in the chamber wall. The theory was extended by Bielajew (PMB 1990) using an anisotropic electron angular fluence in the cavity. In contrast to the theory by Kondo and Randolph, the anisotropic theory predicts a wall material dependence in the non-uniformity correction factors. This work presents experimental determination of non-uniformity correction factors at distances between 10 and 140 mm from an Ir-192 source. The experimental work makes use of a PTW23331-chamber and Farmer-type chambers (NE2571 and NE2581) with different materials in the walls. The results of the experiments agree well with the anisotropic theory. Due to the geometrical shape of the NE-type chambers, it is shown that the full length of the these chambers, 24.1mm, is not an appropriate input parameter when theoretical non-uniformity correction factors are evaluated

A Non-Uniformly Under-Sampled Blade Tip-Timing Signal Reconstruction Method for Blade Vibration Monitoring

Directory of Open Access Journals (Sweden)

Zheng Hu

2015-01-01

Full Text Available High-speed blades are often prone to fatigue due to severe blade vibrations. In particular, synchronous vibrations can cause irreversible damages to the blade. Blade tip-timing methods (BTT have become a promising way to monitor blade vibrations. However, synchronous vibrations are unsuitably monitored by uniform BTT sampling. Therefore, non-equally mounted probes have been used, which will result in the non-uniformity of the sampling signal. Since under-sampling is an intrinsic drawback of BTT methods, how to analyze non-uniformly under-sampled BTT signals is a big challenge. In this paper, a novel reconstruction method for non-uniformly under-sampled BTT data is presented. The method is based on the periodically non-uniform sampling theorem. Firstly, a mathematical model of a non-uniform BTT sampling process is built. It can be treated as the sum of certain uniform sample streams. For each stream, an interpolating function is required to prevent aliasing in the reconstructed signal. Secondly, simultaneous equations of all interpolating functions in each sub-band are built and corresponding solutions are ultimately derived to remove unwanted replicas of the original signal caused by the sampling, which may overlay the original signal. In the end, numerical simulations and experiments are carried out to validate the feasibility of the proposed method. The results demonstrate the accuracy of the reconstructed signal depends on the sampling frequency, the blade vibration frequency, the blade vibration bandwidth, the probe static offset and the number of samples. In practice, both types of blade vibration signals can be particularly reconstructed by non-uniform BTT data acquired from only two probes.

Semi-quantum Secure Direct Communication Scheme Based on Bell States

Science.gov (United States)

Xie, Chen; Li, Lvzhou; Situ, Haozhen; He, Jianhao

2018-06-01

Recently, the idea of semi-quantumness has been often used in designing quantum cryptographic schemes, which allows some of the participants of a quantum cryptographic scheme to remain classical. One of the reasons why this idea is popular is that it allows a quantum information processing task to be accomplished by using quantum resources as few as possible. In this paper, we extend the idea to quantum secure direct communication(QSDC) by proposing a semi-quantum secure direct communication scheme. In the scheme, the message sender, Alice, encodes each bit into a Bell state |φ+> = 1/{√2}(|00> +|11> ) or |{Ψ }+> = 1/{√ 2}(|01> +|10> ), and the message receiver, Bob, who is classical in the sense that he can either let the qubit he received reflect undisturbed, or measure the qubit in the computational basis |0>, |1> and then resend it in the state he found. Moreover, the security analysis of our scheme is also given.

Surface magnetic canting in a nonuniform film

International Nuclear Information System (INIS)

Pini, M.G.; Rettori, A.; Pappas, D.P.; Anisimov, A.V.; Popov, A.P.

2004-01-01

The zero temperature equilibrium configuration of a nonuniform system made of a ferromagnetic (FM) monolayer on top of a semi-infinite FM film is calculated using a nonlinear mapping formulation of mean-field theory, where the surface is taken into account via an appropriate boundary condition. The analytical criterion for the existence of surface magnetic canting, previously obtained by Popov and Pappas, is also recovered

Asynchronous Channel-Hopping Scheme under Jamming Attacks

Directory of Open Access Journals (Sweden)

Yongchul Kim

2018-01-01

Full Text Available Cognitive radio networks (CRNs are considered an attractive technology to mitigate inefficiency in the usage of licensed spectrum. CRNs allow the secondary users (SUs to access the unused licensed spectrum and use a blind rendezvous process to establish communication links between SUs. In particular, quorum-based channel-hopping (CH schemes have been studied recently to provide guaranteed blind rendezvous in decentralized CRNs without using global time synchronization. However, these schemes remain vulnerable to jamming attacks. In this paper, we first analyze the limitations of quorum-based rendezvous schemes called asynchronous channel hopping (ACH. Then, we introduce a novel sequence sensing jamming attack (SSJA model in which a sophisticated jammer can dramatically reduce the rendezvous success rates of ACH schemes. In addition, we propose a fast and robust asynchronous rendezvous scheme (FRARS that can significantly enhance robustness under jamming attacks. Our numerical results demonstrate that the performance of the proposed scheme vastly outperforms the ACH scheme when there are security concerns about a sequence sensing jammer.

Improving the quality factor of an RF spiral inductor with non-uniform metal width and non-uniform coil spacing

International Nuclear Information System (INIS)

Shen Pei; Zhang Wanrong; Huang Lu; Jin Dongyue; Xie Hongyun

2011-01-01

An improved inductor layout with non-uniform metal width and non-uniform spacing is proposed to increase the quality factor (Q factor). For this inductor layout, from outer coil to inner coil, the metal width is reduced by an arithmetic-progression step, while the metal spacing is increased by a geometric-progression step. An improved layout with variable width and changed spacing is of benefit to the Q factor of RF spiral inductor improvement (approximately 42.86%), mainly due to the suppression of eddy-current loss by weakening the current crowding effect in the center of the spiral inductor. In order to increase the Q factor further, for the novel inductor, a patterned ground shield is used with optimized layout together. The results indicate that, in the range of 0.5 to 16 GHz, the Q factor of the novel inductor is at an optimum, which improves by 67% more than conventional inductors with uniform geometry dimensions (equal width and equal spacing), is enhanced by nearly 23% more than a PGS inductor with uniform geometry dimensions, and improves by almost 20% more than an inductor with an improved layout. (semiconductor devices)

The use of non-uniform drowning terminology: a follow-up study.

Science.gov (United States)

Schmidt, Andrew C; Sempsrott, Justin R; Szpilman, David; Queiroga, Ana Catarina; Davison, Matt S; Zeigler, Ryan J; McAlister, Sean J

2017-07-17

In 2002, the World Congress on Drowning developed a uniform definition for drowning. The aim of this study is to determine the prevalence of "non-uniform drowning terminology" (NUDT) and "non-uniform drowning definitions" (NUDD) in peer-reviewed scientific literature from 2010 to 2016, and compare these findings with those from our unpublished study performing a similar analysis on literature from 2003 to 2010. A systematic review was performed using drowning-specific search terms in Pubmed and Web of Science. Titles and abstracts published between July 2010 and January 2016 were screened for relevance to the study focus. Articles meeting screening criteria were reviewed for exclusion criteria to produce the final group of studies. These articles were reviewed by four reviewers for NUDT and NUDD. The Fisher exact test was used to determine any statistically significant changes. The final group of studies included 167 articles. A total of 53 articles (32%) utilized NUDT, with 100% of these including the term "near drowning". The proportion of articles utilizing NUDT was significantly less than reported by our previous study (p drowning (uniform or non-uniform), with 15% of these utilizing NUDD. Our study reveals a statistically significant improvement over the past thirteen years in the use of uniform drowning terminology in peer-reviewed scientific literature, although year-to-year variability over the current study period does not yield an obvious trend. Of the articles reviewed during the 2010-2016 study period, 32% included outdated and non-uniform drowning terminology and definitions. While this reveals an absolute decrease of 11% as compared with the previous study period (2003-2010), there is still significant room for improvement.

Analysis of Quantum Effects in Non-Uniformly Doped MOS Structures

National Research Council Canada - National Science Library

Fiegna, Claudio

1997-01-01

This paper presents results from the self-consistent solution of Schrodinger and Poisson equations obtained in one-dimensional non-uniformly doped MOS structures suitable for the fabrication of very short transistors...

Effects of non-uniformities on electrical conduction in weakly ionized plasmas

International Nuclear Information System (INIS)

Numano, M.; Murakami, Y.; Nitta, T.

1989-01-01

The effect of non-uniformities on the flow of electric current in weakly ionized plasmas is investigated by taking into account the ion slip as well as the Hall current. An Ohm's law for a non-uniform plasma is derived, from which the formula previously obtained by Numano, i.e. an extension of Rosa's equation, is obtainable as a special case. Making use of this new Ohm's law, the effective electrical conductivity and the effective Hall parameter are determined for isotropically turbulent plasmas. It is found that when the ion-slip effect is absent they are in good agreement with the results obtained previously. (author)

A dynamic model of gas flow in a non-uniform pipe

International Nuclear Information System (INIS)

Mensah, S.; Lepp, R.M.

1979-08-01

A gas-line model, based on the analysis of compressible flow with friction, has been developed to describe the dynamics of gas flow in a non-uniform line, i.e. one comprising segments of different lengths and diameters. Acoustic wave analysis was used in a novel way, by considering the line as a cascaded connection of uniform pipes separated by discontinuities. The transmission matrix representing this non-uniform line is the product of the matrices for each element in the system. To facilitate implementation of the theoretical model on a hybrid computer, modal approximatons to its transfer functions were derived. Both models were validated against experimental data. (author)

The Political Economy of International Emissions Trading Scheme Choice

DEFF Research Database (Denmark)

Boom, Jan-Tjeerd; Svendsen, Jan Tinggard

2000-01-01

The Kyoto Protocol allows emission trade between the Annex B countries. We consider three schemes of emissions trading: government trading, permit trading and credit trading. The schemes are compared in a public choice setting focusing on group size and rent-seeking from interest groups. We find ...

To the problem of spatial focusing of ultracold neutrons by nonuniform magnetic field. Eikonal approximation

CERN Document Server

Chen, T

2002-01-01

Motion of the ultracold neutrons in the nonuniform magnetic field with a square nonuniformity by two coordinates is considered. The Schroedinger equation is solved with application of the quasi-classical (eikonal) approach. The theoretical possibility of the neutrons spatial focusing with formation of the point focus and also the neutrons bunches is shown

Influence of Non-Uniform Magnetic Field on Quantum Teleportation in Heisenberg XY Model

Institute of Scientific and Technical Information of China (English)

SHAO Bin; YANG Tie-jian; ZHAO Yue-hong; ZOU Jian

2007-01-01

By considering the intrinsic decoherence, the validity of quantum teleportation of a two-qubit 1D Heisenberg XY chain in a non-uniform external magnetic field is studied. The fidelity as the measurement of a possible quantum teleportation is calculated and the effects of the non-uniform magnetic field and the intrinsic decoherence are discussed. It is found that anti-parallel magnetic field is more favorable for teleportation and the fidelity is suppressed by the intrinsic decoherence.

An Improved Biometrics-Based Remote User Authentication Scheme with User Anonymity

Directory of Open Access Journals (Sweden)

Muhammad Khurram Khan

2013-01-01

Full Text Available The authors review the biometrics-based user authentication scheme proposed by An in 2012. The authors show that there exist loopholes in the scheme which are detrimental for its security. Therefore the authors propose an improved scheme eradicating the flaws of An’s scheme. Then a detailed security analysis of the proposed scheme is presented followed by its efficiency comparison. The proposed scheme not only withstands security problems found in An’s scheme but also provides some extra features with mere addition of only two hash operations. The proposed scheme allows user to freely change his password and also provides user anonymity with untraceability.

Nonuniform transformation field analysis of multiphase elasto viscoplastic materials: application to MOX fuels

International Nuclear Information System (INIS)

Roussette, S.

2005-05-01

The description of the overall behavior of nonlinear materials with nonlinear dissipative phases requires an infinity of internal variables. An approximate model involving only a finite number of internal variables, Nonuniform Transformation Field Analysis, is obtained by considering a decomposition of these variables on a finite set of nonuniform transformation fields, called plastic modes. The method is initially developed for incompressible elasto viscoplastic materials. Karhunen-Loeve expansion is proposed to optimize the plastic modes. Then the method is extended to porous elasto viscoplastic materials. Finally the transformation field analysis, developed by Dvorak, is applied to nuclear fuels MOX. This method enables to make sensitivity studies to determine the role of some microstructural parameters on the fuel behaviour. Moreover the adequacy of the nonuniform method for fuels MOX is shown, the final objective being to be able to apply the model to the MOX in 3D. (author)

Long GRBs sources population non-uniformity

Science.gov (United States)

Arkhangelskaja, Irene

Long GRBs observed in the very wide energy band. It is possible to separate two subsets of GRBs with high energy component (E > 500 MeV) presence. First type events energy spectra in low and high energy intervals are similar (as for GRB 021008) and described by Band, power law or broken power law models look like to usual bursts without emission in tens MeV region. For example, Band spectrum of GRB080916C covering 6 orders of magnitude. Second ones contain new additional high energy spectral component (for example, GRB 050525B and GRB 090902B). Both types of GRBs observed since CGRO mission beginning. The low energy precursors existence are typical for all types bursts. Both types of bursts temporal profiles can be similar in the various energy regions during some events or different in other cases. The absence of hard to soft evolution in low energy band and (or) presence of high energy precursors for some events are the special features of second class of GRBs by the results of preliminary data analysis and this facts gives opportunities to suppose differences between these two GRBs subsets sources. Also the results of long GRB redshifts distribution analysis have shown its shape contradiction to uniform population objects one for our Metagalaxy to both total and various redshifts definition methods GRBs sources samples. These evidences allow making preliminary conclusion about non-uniformity of long GRBs sources population.

A Practical Voter-Verifiable Election Scheme.

OpenAIRE

Chaum, D; Ryan, PYA; Schneider, SA

2005-01-01

We present an election scheme designed to allow voters to verify that their vote is accurately included in the count. The scheme provides a high degree of transparency whilst ensuring the secrecy of votes. Assurance is derived from close auditing of all the steps of the vote recording and counting process with minimal dependence on the system components. Thus, assurance arises from verification of the election rather than having to place trust in the correct behaviour of components of the vot...

Identification of the material properties in nonuniform nanostructures

International Nuclear Information System (INIS)

Bao, Gang; Xu, Xiang

2015-01-01

This paper is concerned with addressing two significant challenges arising from quantifying mechanical properties of nanomaterials, namely nonuniformity of the nanomaterial and the high noise level of measurements. For nonuniformity, an explicit solution is derived for the general Euler–Bernoulli equation in terms of the Green function for the Poisson equation. Then, by examining a stochastic source, the systematic error may be removed from measurements, which leads to more accurate estimation of mechanical properties. Based on Itô integral properties, three deterministic Fredholm integral equations can be deduced to extract the stiffness and the structure of the random source from measured data. To overcome ill-posedness and high nonlinearity in solving the Fredholm equations, a Tikhonov regularization method is developed with an a priori strategy of choosing the regularization parameter. Moreover, under a regularity assumption for the stiffness coefficient and structures of the random source, the convergence rate can be obtained in the sense of probability. Numerical examples are presented to illustrate the validity and effectiveness of the novel model and regularization method. (paper)

Laterally excited flexible tanks with nonuniform density liquid

International Nuclear Information System (INIS)

Tang, Yu

1996-01-01

A study of the dynamic responses of flexible tanks containing nonuniform liquid under horizontal base excitations is presented. The system considered is an upright, circular cylindrical tank filled with an incompressible and inviscid liquid in which the density increases with the liquid depth. Only the impulsive components of response are considered in this study since the convective components can be computed by considering the tank to be rigid. It is shown in this study that for tanks with height-to-radius ratios between 0.3 and 1.2, the response quantities may be estimated utilizing the rigid tank solutions. Also, it is found that the pressure distribution along the tank wall is not sensitive to the detailed distribution function of the liquid density, and that the base shear and moments for the tank with nonuniform liquid can be estimated conservatively by assuming that the tank is filled with an equivalent uniform liquid density that preserves the total liquid weight. Finally, a simple equation for evaluating the fundamental natural frequency of the system is proposed

Potential coherent structures in nonuniform streaming dusty magnetoplasma

Energy Technology Data Exchange (ETDEWEB)

Vranjes, Jovo [Inst. of Physics, Belgrade (Yugoslavia); Shukla, Padma Kant [Ruhr-Universitaet Bochum, Institut fuer Theoretische Physik IV, Bochum (Germany)

2001-07-01

In this paper we study linear and nonlinear behaviour of modified convective cells and vortices in nonuniform dusty magnetoplasmas with perpendicular and parallel to the magnetic field plasma flows, and in basically two different physical systems, with stationary (corresponding to the case of ShuklaVarma mode) and nonstationary (i.e. taking part in perturbations) dust particles. For the case of stationary dust, by choosing some specific profiles for the sheared plasma flow and the dust density, we analyze the eigenvalue equation in order to deduce the growth rate. A threshold is also obtained for the wavenumber separating spatially damped and convective modes (growing in space) due to its interaction with the sheared plasma flow. In the nonlinear regime, for both stationary and nonstationary dust particles, and in the presence of various plasma flows perpendicular and parallel to the magnetic field lines, a variety of possible nonlinear solutions, driven by the nonuniform shear flow and dust density is presented, i.e., single and double vortex chains accompanied with zonal flows, and tripolar and global vortices. (author)

Scaled nonuniform Fourier transform for image reconstruction in swept source optical coherence tomography

Science.gov (United States)

Mezgebo, Biniyam; Nagib, Karim; Fernando, Namal; Kordi, Behzad; Sherif, Sherif

2018-02-01

Swept Source optical coherence tomography (SS-OCT) is an important imaging modality for both medical and industrial diagnostic applications. A cross-sectional SS-OCT image is obtained by applying an inverse discrete Fourier transform (DFT) to axial interferograms measured in the frequency domain (k-space). This inverse DFT is typically implemented as a fast Fourier transform (FFT) that requires the data samples to be equidistant in k-space. As the frequency of light produced by a typical wavelength-swept laser is nonlinear in time, the recorded interferogram samples will not be uniformly spaced in k-space. Many image reconstruction methods have been proposed to overcome this problem. Most such methods rely on oversampling the measured interferogram then use either hardware, e.g., Mach-Zhender interferometer as a frequency clock module, or software, e.g., interpolation in k-space, to obtain equally spaced samples that are suitable for the FFT. To overcome the problem of nonuniform sampling in k-space without any need for interferogram oversampling, an earlier method demonstrated the use of the nonuniform discrete Fourier transform (NDFT) for image reconstruction in SS-OCT. In this paper, we present a more accurate method for SS-OCT image reconstruction from nonuniform samples in k-space using a scaled nonuniform Fourier transform. The result is demonstrated using SS-OCT images of Axolotl salamander eggs.

Joint multiuser switched diversity and adaptive modulation schemes for spectrum sharing systems

KAUST Repository

Qaraqe, Marwa

2012-12-01

In this paper, we develop multiuser access schemes for spectrum sharing systems whereby secondary users are allowed to share the spectrum with primary users under the condition that the interference observed at the primary receiver is below a predetermined threshold. In particular, we devise two schemes for selecting a user among those that satisfy the interference constraint and achieve an acceptable signal-to-noise ratio level. The first scheme selects the user that reports the best channel quality. In order to alleviate the high feedback load associated with the first scheme, we develop a second scheme based on the concept of switched diversity where the base station scans the users in a sequential manner until an acceptable user is found. In addition to these two selection schemes, we consider two power adaptive settings at the secondary users based on the amount of interference available at the secondary transmitter. In the On/Off power setting, users are allowed to transmit based on whether the interference constraint is met or not, while in the full power adaptive setting, the users are allowed to vary their transmission power to satisfy the interference constraint. Finally, we present numerical results for our proposed algorithms where we show the trade-off between the average spectral efficiency and average feedback load for both schemes. © 2012 IEEE.

Joint multiuser switched diversity and adaptive modulation schemes for spectrum sharing systems

KAUST Repository

Qaraqe, Marwa; Abdallah, Mohamed M.; Serpedin, Erchin; Alouini, Mohamed-Slim; Alnuweiri, Hussein M.

2012-01-01

In this paper, we develop multiuser access schemes for spectrum sharing systems whereby secondary users are allowed to share the spectrum with primary users under the condition that the interference observed at the primary receiver is below a predetermined threshold. In particular, we devise two schemes for selecting a user among those that satisfy the interference constraint and achieve an acceptable signal-to-noise ratio level. The first scheme selects the user that reports the best channel quality. In order to alleviate the high feedback load associated with the first scheme, we develop a second scheme based on the concept of switched diversity where the base station scans the users in a sequential manner until an acceptable user is found. In addition to these two selection schemes, we consider two power adaptive settings at the secondary users based on the amount of interference available at the secondary transmitter. In the On/Off power setting, users are allowed to transmit based on whether the interference constraint is met or not, while in the full power adaptive setting, the users are allowed to vary their transmission power to satisfy the interference constraint. Finally, we present numerical results for our proposed algorithms where we show the trade-off between the average spectral efficiency and average feedback load for both schemes. © 2012 IEEE.

Protostellar formation in rotating interstellar clouds. VI. Nonuniform initial conditions

International Nuclear Information System (INIS)

Boss, A.P.

1987-01-01

The collapse and fragmentation of rotating protostellar clouds is explored, starting from nonuniform density and nonuniform rotation initial conditions. Whether binary fragmentation occurs during the first dynamic collapse phase depends strongly on the initial density profile. Exponential clouds are only somewhat more resistant to fragmentation than uniform-density clouds, but power-law clouds do not undergo fragmentation for likely values of a relevant parameter. Because binary fragments start from profiles intermediate between uniform density and exponential clouds, minimum protostellar mass for population I stars should be increased to approximately 0.02 solar mass. The axisymmetric Terey et al. (1984) model should be stable with respect to nonaxisymmetric perturbations. Considering the observed binary frequency, collapse from power-law initial conditions appears to be less common than collapse from more uniform initial conditions. 34 references

Study of submelt laser induced junction nonuniformities using Therma-Probe

DEFF Research Database (Denmark)

Rosseel, E.; Bogdanowicz, J; Clarysse, T.

2010-01-01

to standard and micro-four-point probe sheet resistance data, secondary ion mass spectrometry, and Hall measurements obtained during earlier studies. Besides the impact of the nonuniformities on the “conventional” thermal wave signal, they found a strong correlation to the dc reflectance of the probe laser...... both at macroscopic and microscopic levels. In this work, the authors present high resolution Therma-Probe® measurements to assess the junction nonuniformity on 0.5 keV boron junctions and zoom in on the effect of temperature variations and multiple subsequent laser scans. The results are compared...... (lambda = 675 nm). The dc probe reflectance is dominated by free carriers and is highly correlated to the sheet resistance both on blanket wafers and on real device wafers. ©2010 American Vacuum Society...

Exploring field-of-view non-uniformities produced by a hand-held spectroradiometer

Directory of Open Access Journals (Sweden)

Tamir Caras

2011-01-01

Full Text Available The shape of a spectroradiometer’s field of view (FOV affects the way spectral measurements are acquired. Knowing this property is a prerequisite for the correct use of the spectrometer. If the substrate is heterogeneous, the ability to accurately know what is being measured depends on knowing the FOV location, shape, spectral and spatial sensitivity. The GER1500 is a hand-held spectrometer with a fixed lens light entry slit and has a laser guide that allows control over the target by positioning the entire unit. In the current study, the FOV of the GER1500 was mapped and analysed. The spectral and spatial non-uniformities of the FOV were examined and were found to be spectrally independent. The relationship between the FOV and the built-in laser guide was tested and found to have a linear displacement dependent on the distance to the target. This allows an accurate prediction of the actual FOV position. A correction method to improve the agreement between the expected and measured reflectance over heterogeneous targets was developed and validated. The methods described are applicable and may be of use with other hand-held spectroradiometers.

Effects of Long- and Intermediate-Wavelength Nonuniformities on Hot-Spot Energetics of Hydrodynamic Equivalent Targets

Science.gov (United States)

Bose, A.; Betti, R.; Woo, K. M.; Christopherson, A. R.; Shvarts, D.

2015-11-01

The impact of intermediate- and low-mode nonuniformities on the performance of inertial confinement fusion (ICF) implosions is investigated by a detailed study of hot-spot energetics. It is found that low- (1 ~ 2) and intermediate-mode (1 >= 10) asymmetries affect the hot-spot hydrodynamics in very different ways. It is observed that for low-mode asymmetries, the fusion yield decreases because of a significant reduction in hot-spot pressure while the neutron-averaged hot-spot volume remains comparable to that of unperturbed (clean) simulations. On the other hand, implosions with moderate-amplitude, intermediate-wavelength modes, which are amplified by the Rayleigh-Taylor instability (RTI), exhibit a fusion-yield degradation primarily caused by a reduction in the burn volume without significant degradation of the pressure. For very large amplitudes, the intermediate modes show a ``secondary piston effect,'' where the converging RTI spikes compress a much smaller volume, allowing for a secondary conversion of the shell's kinetic energy to internal energy at a central region. Understanding the effects of nonuniformities on the hot-spot energetics provides valuable insight in determining the causes of performance degradation in current ICF experiments. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944 and DE-FC02-04ER54789 (Fusion Science Center).

Enhancement of quasi-static strain energy harvesters using non-uniform cross-section post-buckled beams

Science.gov (United States)

Jiao, Pengcheng; Borchani, Wassim; Hasni, Hassene; Lajnef, Nizar

2017-08-01

Thanks to their efficiency enhancement systems based on post-buckled structural elements have been extensively used in many applications such as actuation, remote sensing and energy harvesting. The post-buckling snap-through behavior of bilaterally constrained beams has been exploited to create sensing or energy harvesting mechanisms for quasi-static applications. The conversion mechanism has been used to transform low-rate and low-frequency excitations into high-rate motions. Electric energy has been generated from such high-rate motions using piezoelectric transducers. However, lack of control over the post-buckling behavior severely limits the mechanism’s efficiency. This study aims to maximize the levels of harvestable power by controlling the location of snap-throughs along the beam at different buckling transitions. Since the snap-through location cannot be controlled by tuning the geometric properties of a uniform beam, non-uniform cross-sections are examined. An energy-based theoretical model is herein developed to predict the post-buckling response of non-prismatic beams. The total potential energy is minimized under constraints that represent the physical confinement of the beam between the lateral boundaries. The experimentally validated results show that changing the shape and geometric dimensions of non-uniform beams allows for the accurate controlling of the snap-through location at different buckling transitions. A 78.59% improvement in harvested energy levels has been achieved by optimization of beam shape.

Factors affecting the carbon allowance market in the US

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyun Seok; Koo, Won W. [Center for Agricultural Policy and Trade Studies, Department of Agribusiness and Applied Economics, North Dakota State University, Dept 7610, P.O. Box 6050, Fargo, ND 58103-6050 (United States)

2010-04-15

The US carbon allowance market has different characteristic and price determination process from the EU ETS market, since emitting installations voluntarily participate in emission trading scheme. This paper examines factors affecting the US carbon allowance market. An autoregressive distributed lag model is used to examine the short- and long-run relationships between the US carbon allowance market and its determinant factors. In the long-run, the price of coal is a main factor in the determination of carbon allowance trading. In the short-run, on the other hand, the changes in crude oil and natural gas prices as well as coal price have significant effects on carbon allowance market. (author)

Factors affecting the carbon allowance market in the US

International Nuclear Information System (INIS)

Kim, Hyun Seok; Koo, Won W.

2010-01-01

The US carbon allowance market has different characteristic and price determination process from the EU ETS market, since emitting installations voluntarily participate in emission trading scheme. This paper examines factors affecting the US carbon allowance market. An autoregressive distributed lag model is used to examine the short- and long-run relationships between the US carbon allowance market and its determinant factors. In the long-run, the price of coal is a main factor in the determination of carbon allowance trading. In the short-run, on the other hand, the changes in crude oil and natural gas prices as well as coal price have significant effects on carbon allowance market.

Incentive schemes in development of socio-economic systems

Science.gov (United States)

Grachev, V. V.; Ivushkin, K. A.; Myshlyaev, L. P.

2018-05-01

The paper is devoted to the study of incentive schemes when developing socio-economic systems. The article analyzes the existing incentive schemes. It is established that the traditional incentive mechanisms do not fully take into account the specifics of the creation of each socio-economic system and, as a rule, are difficult to implement. The incentive schemes based on the full-scale simulation approach, which allow the most complete information from the existing projects of creation of socio-economic systems to be extracted, are proposed. The statement of the problem is given, the method and algorithm of the full-scale simulation study of the efficiency of incentive functions is developed. The results of the study are presented. It is shown that the use of quadratic and piecewise linear functions of incentive allows the time and costs for creating social and economic systems to be reduced by 10%-15%.

An efficient quantum scheme for Private Set Intersection

Science.gov (United States)

Shi, Run-hua; Mu, Yi; Zhong, Hong; Cui, Jie; Zhang, Shun

2016-01-01

Private Set Intersection allows a client to privately compute set intersection with the collaboration of the server, which is one of the most fundamental and key problems within the multiparty collaborative computation of protecting the privacy of the parties. In this paper, we first present a cheat-sensitive quantum scheme for Private Set Intersection. Compared with classical schemes, our scheme has lower communication complexity, which is independent of the size of the server's set. Therefore, it is very suitable for big data services in Cloud or large-scale client-server networks.

An efficient shutter-less non-uniformity correction method for infrared focal plane arrays

Science.gov (United States)

Huang, Xiyan; Sui, Xiubao; Zhao, Yao

2017-02-01

The non-uniformity response in infrared focal plane array (IRFPA) detectors has a bad effect on images with fixed pattern noise. At present, it is common to use shutter to prevent from radiation of target and to update the parameters of non-uniformity correction in the infrared imaging system. The use of shutter causes "freezing" image. And inevitably, there exists the problems of the instability and reliability of system, power consumption, and concealment of infrared detection. In this paper, we present an efficient shutter-less non-uniformity correction (NUC) method for infrared focal plane arrays. The infrared imaging system can use the data gaining in thermostat to calculate the incident infrared radiation by shell real-timely. And the primary output of detector except the shell radiation can be corrected by the gain coefficient. This method has been tested in real infrared imaging system, reaching high correction level, reducing fixed pattern noise, adapting wide temperature range.

Additive non-uniform random sampling in superimposed fiber Bragg grating strain gauge

Science.gov (United States)

Ma, Y. C.; Liu, H. Y.; Yan, S. B.; Yang, Y. H.; Yang, M. W.; Li, J. M.; Tang, J.

2013-05-01

This paper demonstrates an additive non-uniform random sampling and interrogation method for dynamic and/or static strain gauge using a reflection spectrum from two superimposed fiber Bragg gratings (FBGs). The superimposed FBGs are designed to generate non-equidistant space of a sensing pulse train in the time domain during dynamic strain gauge. By combining centroid finding with smooth filtering methods, both the interrogation speed and accuracy are improved. A 1.9 kHz dynamic strain is measured by generating an additive non-uniform randomly distributed 2 kHz optical sensing pulse train from a mean 500 Hz triangular periodically changing scanning frequency.

Non-Uniform Dose Mapping Controlled by Modulated Vertical and Horizontal Scans

International Nuclear Information System (INIS)

Ninomiya, S.; Kimura, Y.; Kudo, T.; Ochi, A.; Toda, R.; Tsukihara, M.; Sato, F.; Fuse, G.; Ueno, K.; Sugitani, M.

2008-01-01

Since geometries of semi-conductor devices continue to shrink, the requirement for each process becomes severer to keep uniformity of electrical parameters of the semi-conductor devices. A larger wafer also causes larger variations. Thus it has been strongly required for ion implantation process to compensate for the variations from other processes because of its good dose controllability. A newly developed mapping of intentional non-uniform dosage system, which is named 'MIND system', is implemented in SEN's single-wafer-type implanters. The MIND system controls both horizontal and vertical scan speed simultaneously. Intentional two-dimensional non-uniform profiles of sheet resistance, such as concentric and eccentric profiles, are obtained only by single-step ion implantation.

Low-frequency electrostatic dust-modes in a non-uniform

Indian Academy of Sciences (India)

A self-consistent and general description of obliquely propagating low-frequency electrostatic dust-modes in a non-uniform magnetized dusty plasma system has been presented. A number of different situations, which correspond to different low-frequency electrostatic dust-modes, namely, dust-acoustic mode, dust-drift ...

A two-dimensional finite element model of front surface current flow in cells under non-uniform, concentrated illumination

Energy Technology Data Exchange (ETDEWEB)

Mellor, A.; Domenech-Garret, J.L.; Chemisana, D.; Rosell, J.I. [Departament de Medi Ambient i C.S., University of Lleida, Av. Alcalde Rovira Roure 191, E25198 (Spain)

2009-09-15

A two-dimensional finite element model of current flow in the front surface of a PV cell is presented. In order to validate this model we perform an experimental test. Later, particular attention is paid to the effects of non-uniform illumination in the finger direction which is typical in a linear concentrator system. Fill factor, open circuit voltage and efficiency are shown to decrease with increasing degree of non-uniform illumination. It is shown that these detrimental effects can be mitigated significantly by reoptimization of the number of front surface metallization fingers to suit the degree of non-uniformity. The behavior of current flow in the front surface of a cell operating at open circuit voltage under non-uniform illumination is discussed in detail. (author)

Hot deformation behavior and microstructure evolution of TA15 titanium alloy with nonuniform microstructure

Energy Technology Data Exchange (ETDEWEB)

Gao, Pengfei; Zhan, Mei, E-mail: zhanmei@nwpu.edu.cn; Fan, Xiaoguang; Lei, Zhenni; Cai, Yang

2017-03-24

The flow behavior and microstructure evolution of a near α titanium alloy with nonuniform microstructure during hot deformation were studied by isothermal compression test and electron backscatter diffraction technique. It is found that the nonuniform microstructure prior to deformation consists of equiaxed α, lamellar α in the colony form and β phase, and the α colony keeps the Burgers orientation relationship with β phase. The flow stress of nonuniform microstructure exhibits significant flow softening after reaching the peak stress at a low strain, which is similar to the lamellar microstructure. Nevertheless, the existence of equiaxed α in nonuniform microstructure makes its flow stress and softening rate be lower than the lamellar microstructure. During deformation, the lamellar α undertakes most of the deformation and turns to be rotated, bended and globularized. Moreover, these phenomena exhibit significant heterogeneity due to the orientation dependence of the deformation of lamellar α. The continuous dynamic recrystallization and bending of lamellar α lead to the “fragmentation” during globularization of lamellar α. The bending of lamellar α is speculated as a form of plastic buckling, because the bending of lamellar α almost proceed in the manner of “rigid rotation” and presents opposite bending directions for the adjacent colonies.

CHF multiplier of subcooled flow boiling for non-uniform heating conditions in swirl tube

International Nuclear Information System (INIS)

Inasaka, F.; Nariai, H.

1994-01-01

The high heat flux components of fusion reactors, such as divertor plates and beam dumps of neutral beam injectors, are estimated to be subjected to very high heat loads more than 10 MW/m 2 . Critical heat flux (CHF), which determines the upper limit of heat removal, is one of the most important problems in designing cooling systems. For practical applications in cooling systems, subcooled flow boiling in water combined with swirl-flow in tubes with internal twisted tape is thought to be the most superior for CHF characteristics in fusion reactor components, heat by irradiation comes in from one side of the wall, and cooling channel is then under circumferentially non-uniform heating condition. Authors have conducted the experiments on the CHF with internal twisted tapes under circumferentially non-uniform heating conditions and showed that when the intensity of non-uniformity increased, q cH (peak heat flux at burnout under nonuniform heating condition) in tube with internal twisted tape increased above the q c,unif (CHF under uniform heating condition), though the average qualities were the same for both cases. They also showed that this CHF enhancement was not seen in smooth tubes without tape under the same average qualities

Measurement of reactivity effect caused by nonuniform fuel distribution

International Nuclear Information System (INIS)

Yamane, Yoshihiro; Hirano, Yasushi; Yasui, Hazime; Nishina, Kojiro; Shiroya, Seiji

1991-01-01

A reactivity effect due to a spatial variation of nuclear fuel concentration is an important problem in a reprocessing plant. To estimate this reactivity effect theoretically, the ''Goertzel's necessary condition, and th Fuel Importance'' theory have been proposed. In order to verify these theories, we have performed systematic measurements of reactivity effect due to the nonuniformity in the fuel distribution within the Kyoto University Critical Assembly. Neutron flux distribution and Fuel Importance distribution were also determined. A nonuniform assembly whose fuel concentration in the center region was 40% higher than the uniform one was found to have an excess reactivity of 0.3%Δk/k, with the same total uranium mass for which the uniform assembly was just critical. Moreover, its spatial distribution of thermal neutron flux and of Fuel Importance were more flat than those of the uniform assembly, as expected by the Goertzel's condition and the Fuel Importance theory. (Author)

Influence Of Nonuniformity On Infrared Focal Plane Array Performance

Science.gov (United States)

Milton, A. F.; Barone, F. R.; Kruer, M. R.

1985-08-01

It is well known that detector response nonuniformity results in pattern noise with staring sensors that is a severe problem in the infrared due to the low intrinsic contrast of IR imagery. The pattern noise can be corrected by electronic processing; however, the ability to correct for pattern noise is limited by the interaction of interscene and intrascene variability with the dynamic range of the processor (number of bits) and, depending upon the algorithm used, by nonlinearities in the detector response. This paper quantifies these limitations and describes the interaction of detector gain nonuniformity and detector nonlinearities. Probabilistic models are developed to determine the maximum sensitivity that can be obtained using a two-point algorithm to correct a nonlinear response curve over a wide temperature range. Curves that permit a prediction of the noise equivalent differential temperature (NEAT) under varying circumstances are presented. A piecewise linear approach to dealing with severe detector response nonlinearities is presented and analyzed for its effectiveness.

Nonuniform code concatenation for universal fault-tolerant quantum computing

Science.gov (United States)

Nikahd, Eesa; Sedighi, Mehdi; Saheb Zamani, Morteza

2017-09-01

Using transversal gates is a straightforward and efficient technique for fault-tolerant quantum computing. Since transversal gates alone cannot be computationally universal, they must be combined with other approaches such as magic state distillation, code switching, or code concatenation to achieve universality. In this paper we propose an alternative approach for universal fault-tolerant quantum computing, mainly based on the code concatenation approach proposed in [T. Jochym-O'Connor and R. Laflamme, Phys. Rev. Lett. 112, 010505 (2014), 10.1103/PhysRevLett.112.010505], but in a nonuniform fashion. The proposed approach is described based on nonuniform concatenation of the 7-qubit Steane code with the 15-qubit Reed-Muller code, as well as the 5-qubit code with the 15-qubit Reed-Muller code, which lead to two 49-qubit and 47-qubit codes, respectively. These codes can correct any arbitrary single physical error with the ability to perform a universal set of fault-tolerant gates, without using magic state distillation.

Measurement of fuel importance distribution in non-uniformly distributed fuel systems

International Nuclear Information System (INIS)

Yamane, Yoshihiro; Hirano, Yasushi; Yasui, Hazime; Izima, Kazunori; Shiroya, Seiji; Kobayashi, Keiji.

1995-01-01

A reactivity effect due to a spatial variation of nuclear fuel concentration is an important problem for nuclear criticality safety in a reprocessing plant. As a theory estimating this reactivity effect, the Goertzel and fuel importance theories are well known. It has been shown that the Goertzel's theory is valid in the range of our experiments based on measurements of reactivity effect and thermal neutron flux in non-uniformly distributed fuel systems. On the other hand, there have been no reports concerning systematic experimental studies on the flatness of fuel importance which is a more general index than the Goertzel's theory. It is derived from the perturbation theory that the fuel importance is proportional to the reactivity change resulting from a change of small amount of fuel mass. Using a uniform and three kinds of nonuniform fuel systems consisting of 93.2% enriched uranium plates and polyethylene plates, the fuel importance distributions were measured. As a result, it was found experimentally that the fuel importance distribution became flat, as its reactivity effect became large. Therefore it was concluded that the flatness of fuel importance distribution is the useful index for estimating reactivity effect of non-uniformly distributed fuel system. (author)

Additive operator-difference schemes splitting schemes

CERN Document Server

Vabishchevich, Petr N

2013-01-01

Applied mathematical modeling isconcerned with solving unsteady problems. This bookshows how toconstruct additive difference schemes to solve approximately unsteady multi-dimensional problems for PDEs. Two classes of schemes are highlighted: methods of splitting with respect to spatial variables (alternating direction methods) and schemes of splitting into physical processes. Also regionally additive schemes (domain decomposition methods)and unconditionally stable additive schemes of multi-component splitting are considered for evolutionary equations of first and second order as well as for sy

New Imaging Operation Scheme at VLTI

Science.gov (United States)

Haubois, Xavier

2018-04-01

After PIONIER and GRAVITY, MATISSE will soon complete the set of 4 telescope beam combiners at VLTI. Together with recent developments in the image reconstruction algorithms, the VLTI aims to develop its operation scheme to allow optimized and adaptive UV plane coverage. The combination of spectro-imaging instruments, optimized operation framework and image reconstruction algorithms should lead to an increase of the reliability and quantity of the interferometric images. In this contribution, I will present the status of this new scheme as well as possible synergies with other instruments.

Maximum Likelihood DOA Estimation of Multiple Wideband Sources in the Presence of Nonuniform Sensor Noise

Directory of Open Access Journals (Sweden)

K. Yao

2007-12-01

Full Text Available We investigate the maximum likelihood (ML direction-of-arrival (DOA estimation of multiple wideband sources in the presence of unknown nonuniform sensor noise. New closed-form expression for the direction estimation Cramér-Rao-Bound (CRB has been derived. The performance of the conventional wideband uniform ML estimator under nonuniform noise has been studied. In order to mitigate the performance degradation caused by the nonuniformity of the noise, a new deterministic wideband nonuniform ML DOA estimator is derived and two associated processing algorithms are proposed. The first algorithm is based on an iterative procedure which stepwise concentrates the log-likelihood function with respect to the DOAs and the noise nuisance parameters, while the second is a noniterative algorithm that maximizes the derived approximately concentrated log-likelihood function. The performance of the proposed algorithms is tested through extensive computer simulations. Simulation results show the stepwise-concentrated ML algorithm (SC-ML requires only a few iterations to converge and both the SC-ML and the approximately-concentrated ML algorithm (AC-ML attain a solution close to the derived CRB at high signal-to-noise ratio.

Numerical simulation of effect of laser nonuniformity in interior interface

International Nuclear Information System (INIS)

Yu Xiaojin; Wu Junfeng; Ye Wenhua

2007-01-01

Using the LARED-S code and referring to the NIF direct-drive DT ignition target, the effect of laser nonuniformity on the interior interface in direct-drive spherical implosion with high convergence ratio was numerically studied. The two-dimensional results show that the implosion with high convergence ratio is sensitive to the nonuniformity of driving laser, and the growth of hydrodynamic instability on interior interface destroys the symmetric-drive and reduces the volume of central hot spot observably. Taking the limit that perturbation amplitude is equal to 1/3 radius of central hot spot, the simulation also gives that the requirements for the laser uniformity for different mode number(less than 12) on simple physical model are between 2.5% -0.25%, and the modes between 8-10 have the most rigorous requirement which is about 0.25%. (authors)

Signal multiplexing scheme for LINAC

International Nuclear Information System (INIS)

Sujo, C.I.; Mohan, Shyam; Joshi, Gopal; Singh, S.K.; Karande, Jitendra

2004-01-01

For the proper operation of the LINAC some signals, RF (radio frequency) as well as LF (low frequency) have to be available at the Master Control Station (MCS). These signals are needed to control, calibrate and characterize the RF fields in the resonators. This can be achieved by proper multiplexing of various signals locally and then routing the selected signals to the MCS. A multiplexing scheme has been designed and implemented, which will allow the signals from the selected cavity to the MCS. High isolation between channels and low insertion loss for a given signal are important issues while selecting the multiplexing scheme. (author)

The non-uniformity correction factor for the cylindrical ionization chambers in dosimetry of an HDR 192Ir brachytherapy source

International Nuclear Information System (INIS)

Majumdar, Bishnu; Patel, Narayan Prasad; Vijayan, V.

2006-01-01

The aim of this study is to derive the non-uniformity correction factor for the two therapy ionization chambers for the dose measurement near the brachytherapy source. The two ionization chambers of 0.6 cc and 0.1 cc volume were used. The measurement in air was performed for distances between 0.8 cm and 20 cm from the source in specially designed measurement jig. The non-uniformity correction factors were derived from the measured values. The experimentally derived factors were compared with the theoretically calculated non-uniformity correction factors and a close agreement was found between these two studies. The experimentally derived non-uniformity correction factor supports the anisotropic theory. (author)

Bridge density functional approximation for non-uniform hard core repulsive Yukawa fluid

International Nuclear Information System (INIS)

Zhou Shiqi

2008-01-01

In this work, a bridge density functional approximation (BDFA) (J. Chem. Phys. 112, 8079 (2000)) for a non-uniform hard-sphere fluid is extended to a non-uniform hard-core repulsive Yukawa (HCRY) fluid. It is found that the choice of a bulk bridge functional approximation is crucial for both a uniform HCRY fluid and a non-uniform HCRY fluid. A new bridge functional approximation is proposed, which can accurately predict the radial distribution function of the bulk HCRY fluid. With the new bridge functional approximation and its associated bulk second order direct correlation function as input, the BDFA can be used to well calculate the density profile of the HCRY fluid subjected to the influence of varying external fields, and the theoretical predictions are in good agreement with the corresponding simulation data. The calculated results indicate that the present BDFA captures quantitatively the phenomena such as the coexistence of solid-like high density phase and low density gas phase, and the adsorption properties of the HCRY fluid, which qualitatively differ from those of the fluids combining both hard-core repulsion and an attractive tail. (condensed matter: structure, thermal and mechanical properties)

A Cell-Centered Multiphase ALE Scheme With Structural Coupling

Energy Technology Data Exchange (ETDEWEB)

Dunn, Timothy Alan [Univ. of California, Davis, CA (United States)

2012-04-16

A novel computational scheme has been developed for simulating compressible multiphase flows interacting with solid structures. The multiphase fluid is computed using a Godunov-type finite-volume method. This has been extended to allow computations on moving meshes using a direct arbitrary-Eulerian- Lagrangian (ALE) scheme. The method has been implemented within a Lagrangian hydrocode, which allows modeling the interaction with Lagrangian structural regions. Although the above scheme is general enough for use on many applications, the ultimate goal of the research is the simulation of heterogeneous energetic material, such as explosives or propellants. The method is powerful enough for application to all stages of the problem, including the initial burning of the material, the propagation of blast waves, and interaction with surrounding structures. The method has been tested on a number of canonical multiphase tests as well as fluid-structure interaction problems.

Dynamic behaviour of non-uniform Bernoulli-Euler beams subjected ...

African Journals Online (AJOL)

This paper investigates the dynamics behaviour of non-uniform Bernoulli-Euler beams subjected to concentrated loads ravelling at variable velocities. The solution technique is based on the Generalized Galerkin Method and the use of the generating function of the Bessel function type. The results show that, for all the ...

Many-junction photovoltaic device performance under non-uniform high-concentration illumination

Science.gov (United States)

Valdivia, Christopher E.; Wilkins, Matthew M.; Chahal, Sanmeet S.; Proulx, Francine; Provost, Philippe-Olivier; Masson, Denis P.; Fafard, Simon; Hinzer, Karin

2017-09-01

A parameterized 3D distributed circuit model was developed to calculate the performance of III-V solar cells and photonic power converters (PPC) with a variable number of epitaxial vertically-stacked pn junctions. PPC devices are designed with many pn junctions to realize higher voltages and to operate under non-uniform illumination profiles from a laser or LED. Performance impacts of non-uniform illumination were greatly reduced with increasing number of junctions, with simulations comparing PPC devices with 3 to 20 junctions. Experimental results using Azastra Opto's 12- and 20-junction PPC illuminated by an 845 nm diode laser show high performance even with a small gap between the PPC and optical fiber output, until the local tunnel junction limit is reached.

Additive non-uniform random sampling in superimposed fiber Bragg grating strain gauge

International Nuclear Information System (INIS)

Ma, Y C; Liu, H Y; Yan, S B; Li, J M; Tang, J; Yang, Y H; Yang, M W

2013-01-01

This paper demonstrates an additive non-uniform random sampling and interrogation method for dynamic and/or static strain gauge using a reflection spectrum from two superimposed fiber Bragg gratings (FBGs). The superimposed FBGs are designed to generate non-equidistant space of a sensing pulse train in the time domain during dynamic strain gauge. By combining centroid finding with smooth filtering methods, both the interrogation speed and accuracy are improved. A 1.9 kHz dynamic strain is measured by generating an additive non-uniform randomly distributed 2 kHz optical sensing pulse train from a mean 500 Hz triangular periodically changing scanning frequency. (paper)

An Improved Rate-Transient Analysis Model of Multi-Fractured Horizontal Wells with Non-Uniform Hydraulic Fracture Properties

Directory of Open Access Journals (Sweden)

Youwei He

2018-02-01

Full Text Available Although technical advances in hydraulically fracturing and drilling enable commercial production from tight reservoirs, oil/gas recovery remains at a low level. Due to the technical and economic limitations of well-testing operations in tight reservoirs, rate-transient analysis (RTA has become a more attractive option. However, current RTA models hardly consider the effect of the non-uniform production on rate decline behaviors. In fact, PLT results demonstrate that production profile is non-uniform. To fill this gap, this paper presents an improved RTA model of multi-fractured horizontal wells (MFHWs to investigate the effects of non-uniform properties of hydraulic fractures (production of fractures, fracture half-length, number of fractures, fracture conductivity, and vertical permeability on rate transient behaviors through the diagnostic type curves. Results indicate obvious differences on the rate decline curves among the type curves of uniform properties of fractures (UPF and non-uniform properties of fractures (NPF. The use of dimensionless production integral derivative curve magnifies the differences so that we can diagnose the phenomenon of non-uniform production. Therefore, it’s significant to incorporate the effects of NPF into the RDA models of MFHWs, and the model proposed in this paper enables us to better evaluate well performance based on long-term production data.

A Method of Sky Ripple Residual Nonuniformity Reduction for a Cooled Infrared Imager and Hardware Implementation.

Science.gov (United States)

Li, Yiyang; Jin, Weiqi; Li, Shuo; Zhang, Xu; Zhu, Jin

2017-05-08

Cooled infrared detector arrays always suffer from undesired ripple residual nonuniformity (RNU) in sky scene observations. The ripple residual nonuniformity seriously affects the imaging quality, especially for small target detection. It is difficult to eliminate it using the calibration-based techniques and the current scene-based nonuniformity algorithms. In this paper, we present a modified temporal high-pass nonuniformity correction algorithm using fuzzy scene classification. The fuzzy scene classification is designed to control the correction threshold so that the algorithm can remove ripple RNU without degrading the scene details. We test the algorithm on a real infrared sequence by comparing it to several well-established methods. The result shows that the algorithm has obvious advantages compared with the tested methods in terms of detail conservation and convergence speed for ripple RNU correction. Furthermore, we display our architecture with a prototype built on a Xilinx Virtex-5 XC5VLX50T field-programmable gate array (FPGA), which has two advantages: (1) low resources consumption; and (2) small hardware delay (less than 10 image rows). It has been successfully applied in an actual system.

Explicit TE/TM scheme for particle beam simulations

International Nuclear Information System (INIS)

Dohlus, M.; Zagorodnov, I.

2008-10-01

In this paper we propose an explicit two-level conservative scheme based on a TE/TM like splitting of the field components in time. Its dispersion properties are adjusted to accelerator problems. It is simpler and faster than the implicit version. It does not have dispersion in the longitudinal direction and the dispersion properties in the transversal plane are improved. The explicit character of the new scheme allows a uniformly stable conformal method without iterations and the scheme can be parallelized easily. It assures energy and charge conservation. A version of this explicit scheme for rotationally symmetric structures is free from the progressive time step reducing for higher order azimuthal modes as it takes place for Yee's explicit method used in the most popular electrodynamics codes. (orig.)

Experimental observation of the inductive electric field and related plasma nonuniformity in high frequency capacitive discharge

International Nuclear Information System (INIS)

Ahn, S. K.; Chang, H. Y.

2008-01-01

To elucidate plasma nonuniformity in high frequency capacitive discharges, Langmuir probe and B-dot probe measurements were carried out in the radial direction in a cylindrical capacitive discharge driven at 90 MHz with argon pressures of 50 and 400 mTorr. Through the measurements, a significant inductive electric field (i.e., time-varying magnetic field) was observed at the radial edge, and it was found that the inductive electric field creates strong plasma nonuniformity at high pressure operation. The plasma nonuniformity at high pressure operation is physically similar to the E-H mode transition typically observed in inductive discharges. This result agrees well with the theories of electromagnetic effects in large area and/or high frequency capacitive discharges

Security of Linear Secret-Sharing Schemes Against Mass Surveillance

DEFF Research Database (Denmark)

Giacomelli, Irene; Olimid, Ruxandra; Ranellucci, Samuel

2015-01-01

by a proprietary code that the provider (“big brother”) could manipulate to covertly violate the privacy of the users (by implementing Algorithm-Substitution Attacks or ASAs). First, we formalize the security notion that expresses the goal of big brother and prove that for any linear secret-sharing scheme...... there exists an undetectable subversion of it that efficiently allows surveillance. Second, we formalize the security notion that assures that a sharing scheme is secure against ASAs and construct the first sharing scheme that meets this notion....

A Single Image Deblurring Algorithm for Nonuniform Motion Blur Using Uniform Defocus Map Estimation

Directory of Open Access Journals (Sweden)

Chia-Feng Chang

2017-01-01

Full Text Available One of the most common artifacts in digital photography is motion blur. When capturing an image under dim light by using a handheld camera, the tendency of the photographer’s hand to shake causes the image to blur. In response to this problem, image deblurring has become an active topic in computational photography and image processing in recent years. From the view of signal processing, image deblurring can be reduced to a deconvolution problem if the kernel function of the motion blur is assumed to be shift invariant. However, the kernel function is not always shift invariant in real cases; for example, in-plane rotation of a camera or a moving object can blur different parts of an image according to different kernel functions. An image that is degraded by multiple blur kernels is called a nonuniform blur image. In this paper, we propose a novel single image deblurring algorithm for nonuniform motion blur images that is blurred by moving object. First, a proposed uniform defocus map method is presented for measurement of the amounts and directions of motion blur. These blurred regions are then used to estimate point spread functions simultaneously. Finally, a fast deconvolution algorithm is used to restore the nonuniform blur image. We expect that the proposed method can achieve satisfactory deblurring of a single nonuniform blur image.

Novel communication scheme based on chaotic Roessler circuits

International Nuclear Information System (INIS)

GarcIa-Lopez, J H; Jaimes-Reategui, R; Pisarchik, A N; MurguIa-Hernandez, A; Medina-Gutierrez, C; Valdivia-Hernadez, R; Villafana-Rauda, E

2005-01-01

We present a novel synchronization scheme for secure communication with two chaotic unidirectionally coupled Roessler circuits. The circuits are synchronized via one of the variables, while a signal is transmitted through another variable. We show that this scheme allows more stable communications. The system dynamics is studied numerically and experimentally in a wide range of a control parameter. The possibility of secure communications with an audio signal is demonstrated

Beam pattern improvement by compensating array nonuniformities in a guided wave phased array

International Nuclear Information System (INIS)

Kwon, Hyu-Sang; Lee, Seung-Seok; Kim, Jin-Yeon

2013-01-01

This paper presents a simple data processing algorithm which can improve the performance of a uniform circular array based on guided wave transducers. The algorithm, being intended to be used with the delay-and-sum beamformer, effectively eliminates the effects of nonuniformities that can significantly degrade the beam pattern. Nonuniformities can arise intrinsically from the array geometry when the circular array is transformed to a linear array for beam steering and extrinsically from unequal conditions of transducers such as element-to-element variations of sensitivity and directivity. The effects of nonuniformities are compensated by appropriately imposing weight factors on the elements in the projected linear array. Different cases are simulated, where the improvements of the beam pattern, especially the level of the highest sidelobe, are clearly seen, and related issues are discussed. An experiment is performed which uses A0 mode Lamb waves in a steel plate, to demonstrate the usefulness of the proposed method. The discrepancy between theoretical and experimental beam patterns is explained by accounting for near-field effects. (paper)

Non-uniform cosine modulated filter banks using meta-heuristic algorithms in CSD space

Directory of Open Access Journals (Sweden)

Shaeen Kalathil

2015-11-01

Full Text Available This paper presents an efficient design of non-uniform cosine modulated filter banks (CMFB using canonic signed digit (CSD coefficients. CMFB has got an easy and efficient design approach. Non-uniform decomposition can be easily obtained by merging the appropriate filters of a uniform filter bank. Only the prototype filter needs to be designed and optimized. In this paper, the prototype filter is designed using window method, weighted Chebyshev approximation and weighted constrained least square approximation. The coefficients are quantized into CSD, using a look-up-table. The finite precision CSD rounding, deteriorates the filter bank performances. The performances of the filter bank are improved using suitably modified meta-heuristic algorithms. The different meta-heuristic algorithms which are modified and used in this paper are Artificial Bee Colony algorithm, Gravitational Search algorithm, Harmony Search algorithm and Genetic algorithm and they result in filter banks with less implementation complexity, power consumption and area requirements when compared with those of the conventional continuous coefficient non-uniform CMFB.

Complete mechanical behavior analysis of FG Nano Beam under non-uniform loading using non-local theory

Science.gov (United States)

Ghaffari, I.; Parhizkar Yaghoobi, M.; Ghannad, M.

2018-01-01

The purpose of this study is to offer a complete solution to analyze the mechanical behavior (bending, buckling and vibration) of Nano-beam under non-uniform loading. Furthermore, the effects of size (nonlocal parameters), non-homogeneity constants, and different boundary conditions are investigated by using this method. The exact solution presented here reduces costs incurred by experiments. In this research, the displacement field obeys the kinematics of the Euler-Bernoulli beam theory and non-local elasticity theory has been used. The governing equations and general boundary conditions are derived for a beam by using energy method. The presented solution enables us to analyze any kind of loading profile and boundary conditions with no limitations. Furthermore, this solution, unlike previous studies, is not a series-solution; hence, there is no limitation prior to existing with the series-solution, nor does it need to check convergence. Based on the developed analytical solution, the influence of size, non-homogeneity and non-uniform loads on bending, buckling and vibration behaviors is discussed. Also, the obtained result is highly accurate and in good agreement with previous research. In theoretical method, the allowable range for non-local parameters can be determined so as to make a major contribution to the reduction of the cost of experiments determining the value of non-local parameters.

Analysis of central and upwind compact schemes

International Nuclear Information System (INIS)

Sengupta, T.K.; Ganeriwal, G.; De, S.

2003-01-01

Central and upwind compact schemes for spatial discretization have been analyzed with respect to accuracy in spectral space, numerical stability and dispersion relation preservation. A von Neumann matrix spectral analysis is developed here to analyze spatial discretization schemes for any explicit and implicit schemes to investigate the full domain simultaneously. This allows one to evaluate various boundary closures and their effects on the domain interior. The same method can be used for stability analysis performed for the semi-discrete initial boundary value problems (IBVP). This analysis tells one about the stability for every resolved length scale. Some well-known compact schemes that were found to be G-K-S and time stable are shown here to be unstable for selective length scales by this analysis. This is attributed to boundary closure and we suggest special boundary treatment to remove this shortcoming. To demonstrate the asymptotic stability of the resultant schemes, numerical solution of the wave equation is compared with analytical solution. Furthermore, some of these schemes are used to solve two-dimensional Navier-Stokes equation and a computational acoustic problem to check their ability to solve problems for long time. It is found that those schemes, that were found unstable for the wave equation, are unsuitable for solving incompressible Navier-Stokes equation. In contrast, the proposed compact schemes with improved boundary closure and an explicit higher-order upwind scheme produced correct results. The numerical solution for the acoustic problem is compared with the exact solution and the quality of the match shows that the used compact scheme has the requisite DRP property

Modeling of parallel-plate regenerators with non-uniform plate distributions

DEFF Research Database (Denmark)

Jensen, Jesper Buch; Engelbrecht, Kurt; Bahl, Christian Robert Haffenden

2010-01-01

plate spacing distributions are presented in order to understand the impact of spacing non-uniformity. Simulations of more realistic distributions where the plate spacings follow normal distributions are then discussed in order to describe the deviation of the performance of a regenerator relative...

A novel scene-based non-uniformity correction method for SWIR push-broom hyperspectral sensors

Science.gov (United States)

Hu, Bin-Lin; Hao, Shi-Jing; Sun, De-Xin; Liu, Yin-Nian

2017-09-01

A novel scene-based non-uniformity correction (NUC) method for short-wavelength infrared (SWIR) push-broom hyperspectral sensors is proposed and evaluated. This method relies on the assumption that for each band there will be ground objects with similar reflectance to form uniform regions when a sufficient number of scanning lines are acquired. The uniform regions are extracted automatically through a sorting algorithm, and are used to compute the corresponding NUC coefficients. SWIR hyperspectral data from airborne experiment are used to verify and evaluate the proposed method, and results show that stripes in the scenes have been well corrected without any significant information loss, and the non-uniformity is less than 0.5%. In addition, the proposed method is compared to two other regular methods, and they are evaluated based on their adaptability to the various scenes, non-uniformity, roughness and spectral fidelity. It turns out that the proposed method shows strong adaptability, high accuracy and efficiency.

Public pensions, family allowances and endogenous demographic change.

Science.gov (United States)

Peters, W

1995-05-01

"A tax-transfer system deals with redistribution a PAYGmong generations and corrective taxation a PAYGt the same time. Since such a policy is a government's task, we take a normative approach and pose the question: Which tax-transfer system should a government apply to maximize social welfare? The framework we consider allows for endogenous demographic aspects...: first, fertility has a great impact on a PAYG [pay-as-you-go] financed pension insurance; and second, through education human capital is accumulated.... We analyzed the optimal extent of a public pension scheme in the presence of external effects of fertility and education on the net domestic product." Pension schemes in Germany and the United States are compared. excerpt

Fine-Grained Forward-Secure Signature Schemes without Random Oracles

DEFF Research Database (Denmark)

Camenisch, Jan; Koprowski, Maciej

2006-01-01

We propose the concept of fine-grained forward-secure signature schemes. Such signature schemes not only provide nonrepudiation w.r.t. past time periods the way ordinary forward-secure signature schemes do but, in addition, allow the signer to specify which signatures of the current time period...... remain valid when revoking the public key. This is an important advantage if the signer produces many signatures per time period as otherwise the signer would have to re-issue those signatures (and possibly re-negotiate the respective messages) with a new key.Apart from a formal model for fine......-grained forward-secure signature schemes, we present practical schemes and prove them secure under the strong RSA assumption only, i.e., we do not resort to the random oracle model to prove security. As a side-result, we provide an ordinary forward-secure scheme whose key-update time is significantly smaller than...

Non-Uniform Cathode Emission Studies of a MIG Gun

Science.gov (United States)

Marchewka, C. D.; Shapiro, M. A.; Sirigiri, J. R.; Temkin, R. J.

2004-11-01

We present the initial results of the modeling of the effect of emission non-uniformity in 96 kV, 40 A Magnetron Injection Gun (MIG) of a 1.5 MW 110 GHz gyrotron using a 3D gun simulation code. The azimuthal emission nonuniformity can lead to increased mode competition and an overall decreased efficiency of the device [1]. The electron beam is modeled from the cathode to a downstream position where the velocity spread saturates using the AMAZE 3D suite of codes. After bench marking the results of the 3D code with 2D codes such as TRAK2D and EGUN, the emitter was modified to simulate asymmetric emission from the cathode to gain an understanding into the effects of inhomogeneous beam current density on the velocity spread and pitch factor of the electron beam. [1] G. S. Nusinovich, A.N. Vlasov, M. Botton, T. M. Antonsen, Jr., S. Cauffman, K. Felch, ``Effect of the azimuthal inhomogeneity of electron emission on gyrotron operation,'' Phys. Plasmas, vol. 8, no. 7, pp. 3473-3479, 2001

Electrostatic ion-cyclotron waves in a nonuniform magnetic field

International Nuclear Information System (INIS)

Cartier, S.L.; D'Angelo, N.; Merlino, R.L.

1985-01-01

The properties of electrostatic ion-cyclotron waves excited in a single-ended cesium Q machine with a nonuniform magnetic field are described. The electrostatic ion-cyclotron waves are generated in the usual manner by drawing an electron current to a small exciter disk immersed in the plasma column. The parallel and perpendicular (to B) wavelengths and phase velocities are determined by mapping out two-dimensional wave phase contours. The wave frequency f depends on the location of the exciter disk in the nonuniform magnetic field, and propagating waves are only observed in the region where f> or approx. =f/sub c/i, where f/sub c/i is the local ion-cyclotron frequency. The parallel phase velocity is in the direction of the electron drift. From measurements of the plasma properties along the axis, it is inferred that the electron drift velocity is not uniform along the entire current channel. The evidence suggests that the waves begin being excited at that axial position where the critical drift velocity is first exceeded, consistent with a current-driven excitation mechanism

Deep convolutional neural networks for dense non-uniform motion deblurring

CSIR Research Space (South Africa)

Cronje, J

2015-11-01

Full Text Available to form a dense non-uniform motion estimation map. Furthermore, a second CNN is trained to perform deblurring given a blurry image patch and the estimated motion vector. Combining the two trained networks result in a deep learning approach that can enhance...

Hitting emissions targets with (statistical) confidence in multi-instrument Emissions Trading Schemes

International Nuclear Information System (INIS)

Shipworth, David

2003-12-01

A means of assessing, monitoring and controlling aggregate emissions from multi-instrument Emissions Trading Schemes is proposed. The approach allows contributions from different instruments with different forms of emissions targets to be integrated. Where Emissions Trading Schemes are helping to meet specific national targets, the approach allows the entry requirements of new participants to be calculated and set at a level that will achieve these targets. The approach is multi-levelled, and may be extended downwards to support pooling of participants within instruments, or upwards to embed Emissions Trading Schemes within a wider suite of policies and measures with hard and soft targets. Aggregate emissions from each instrument are treated stochastically. Emissions from the scheme as a whole are then the joint probability distribution formed by integrating the emissions from its instruments. Because a Bayesian approach is adopted, qualitative and semi-qualitative data from expert opinion can be used where quantitative data is not currently available, or is incomplete. This approach helps government retain sufficient control over emissions trading scheme targets to allow them to meet their emissions reduction obligations, while minimising the need for retrospectively adjusting existing participants' conditions of entry. This maintains participant confidence, while providing the necessary policy levers for good governance

Factorization method for difference equations of hypergeometric type on nonuniform lattices

Energy Technology Data Exchange (ETDEWEB)

Alvarez-Nodarse, R. [Departamento de Analisis Matematico, Universidad de Sevilla, Sevilla (Spain); Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, Granada (Spain); Costas-Santos, R.S. [Departamento de Analisis Matematico, Universidad de Sevilla, Sevilla (Spain)

2001-07-13

We study the factorization of the hypergeometric-type difference equation of Nikiforov and Uvarov on nonuniform lattices. An explicit form of the raising and lowering operators is derived and some relevant examples are given. (author)

A numerical study on the importance of non-uniform index modification during femtosecond grating inscription in microstructured optical fibers

Science.gov (United States)

Baghdasaryan, Tigran; Geernaert, Thomas; Thienpont, Hugo; Berghmans, Francis

2016-04-01

Fiber Bragg grating (FBG) inscription methods based on femtosecond laser sources are becoming increasingly popular owing to the (usually) non-linear nature of the index modification mechanism and to the resulting advantages. They allow, for example, fabricating fiber gratings that can survive temperatures exceeding 700°C, which can be an asset in the domain of fiber sensing. However applying femtosecond laser based grating fabrication to microstructured optical fibers (MOFs) can be challenging due to the presence of the air holes in the fiber cladding. The microstructured cladding not only impedes light delivery to the core in most cases, but also causes a non-uniform intensity distribution in the MOF core. To deal with these challenges we present a modeling approach that allows simulating how the reflectivity of the grating and the nature of the index modulation are affected by the inscription conditions. We rely on transverse coupling simulations, empirical data and coupled mode analysis to model the induced index change and the resulting grating reflectivity. For IR femtosecond grating inscription we show that due to the intensity redistribution in the core region, irreversible Type II index changes can be induced in a MOF at laser peak intensities below the Type II threshold for step-index fibers. The resulting non-uniform induced index change has repercussions on the reflection spectrum of the grating as well. Our coupled mode analysis reveals, for example, that although the average index change in the core region can be high, the partial overlap of the core mode with the index change region limits the reflectivity of the grating.

Non-uniformity of phase structure in immiscible polymer blends

Czech Academy of Sciences Publication Activity Database

Fortelný, Ivan; Lapčíková, Monika; Lednický, František; Starý, Zdeněk; Kruliš, Zdeněk

2008-01-01

Roč. 48, č. 3 (2008), s. 564-571 ISSN 0032-3888 R&D Projects: GA ČR GA106/06/0729; GA ČR GA106/06/0761 Institutional research plan: CEZ:AV0Z40500505 Keywords : polymer blends * melt mixing * non-uniform morphology Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.245, year: 2008

3D-2D Deformable Image Registration Using Feature-Based Nonuniform Meshes.

Science.gov (United States)

Zhong, Zichun; Guo, Xiaohu; Cai, Yiqi; Yang, Yin; Wang, Jing; Jia, Xun; Mao, Weihua

2016-01-01

By using prior information of planning CT images and feature-based nonuniform meshes, this paper demonstrates that volumetric images can be efficiently registered with a very small portion of 2D projection images of a Cone-Beam Computed Tomography (CBCT) scan. After a density field is computed based on the extracted feature edges from planning CT images, nonuniform tetrahedral meshes will be automatically generated to better characterize the image features according to the density field; that is, finer meshes are generated for features. The displacement vector fields (DVFs) are specified at the mesh vertices to drive the deformation of original CT images. Digitally reconstructed radiographs (DRRs) of the deformed anatomy are generated and compared with corresponding 2D projections. DVFs are optimized to minimize the objective function including differences between DRRs and projections and the regularity. To further accelerate the above 3D-2D registration, a procedure to obtain good initial deformations by deforming the volume surface to match 2D body boundary on projections has been developed. This complete method is evaluated quantitatively by using several digital phantoms and data from head and neck cancer patients. The feature-based nonuniform meshing method leads to better results than either uniform orthogonal grid or uniform tetrahedral meshes.

3D-2D Deformable Image Registration Using Feature-Based Nonuniform Meshes

Directory of Open Access Journals (Sweden)

Zichun Zhong

2016-01-01

Full Text Available By using prior information of planning CT images and feature-based nonuniform meshes, this paper demonstrates that volumetric images can be efficiently registered with a very small portion of 2D projection images of a Cone-Beam Computed Tomography (CBCT scan. After a density field is computed based on the extracted feature edges from planning CT images, nonuniform tetrahedral meshes will be automatically generated to better characterize the image features according to the density field; that is, finer meshes are generated for features. The displacement vector fields (DVFs are specified at the mesh vertices to drive the deformation of original CT images. Digitally reconstructed radiographs (DRRs of the deformed anatomy are generated and compared with corresponding 2D projections. DVFs are optimized to minimize the objective function including differences between DRRs and projections and the regularity. To further accelerate the above 3D-2D registration, a procedure to obtain good initial deformations by deforming the volume surface to match 2D body boundary on projections has been developed. This complete method is evaluated quantitatively by using several digital phantoms and data from head and neck cancer patients. The feature-based nonuniform meshing method leads to better results than either uniform orthogonal grid or uniform tetrahedral meshes.

A Hybrid Single-Carrier/Multicarrier Transmission Scheme with Power Allocation

Directory of Open Access Journals (Sweden)

Luc Féty

2007-11-01

Full Text Available We propose a flexible transmission scheme which easily allows to switch between cyclic-prefixed single-carrier (CP-SC and cyclic-prefixed multicarrier (CP-MC transmissions. This scheme takes advantage of the best characteristic of each scheme, namely, the low peak-to-average power ratio (PAPR of the CP-SC scheme and the robustness to channel selectivity of the CP-MC scheme. Moreover, we derive the optimum power allocation for the CP-SC transmission considering a zero-forcing (ZF and a minimum mean-square error (MMSE receiver. By taking the PAPR into account, we are able to make a better analysis of the overall system and the results show the advantage of the CP-SC-MMSE scheme for flat and mild selective channels due to their low PAPR and that the CP-MC scheme is more advantageous for a narrow range of channels with severe selectivity.

Measurement of Anisotropic Particle Interactions with Nonuniform ac Electric Fields.

Science.gov (United States)

Rupp, Bradley; Torres-Díaz, Isaac; Hua, Xiaoqing; Bevan, Michael A

2018-02-20

Optical microscopy measurements are reported for single anisotropic polymer particles interacting with nonuniform ac electric fields. The present study is limited to conditions where gravity confines particles with their long axis parallel to the substrate such that particles can be treated using quasi-2D analysis. Field parameters are investigated that result in particles residing at either electric field maxima or minima and with long axes oriented either parallel or perpendicular to the electric field direction. By nonintrusively observing thermally sampled positions and orientations at different field frequencies and amplitudes, a Boltzmann inversion of the time-averaged probability of states yields kT-scale energy landscapes (including dipole-field, particle-substrate, and gravitational potentials). The measured energy landscapes show agreement with theoretical potentials using particle conductivity as the sole adjustable material property. Understanding anisotropic particle-field energy landscapes vs field parameters enables quantitative control of local forces and torques on single anisotropic particles to manipulate their position and orientation within nonuniform fields.

Decentralized Economic Dispatch Scheme With Online Power Reserve for Microgrids

DEFF Research Database (Denmark)

Nutkani, I. U.; Loh, Poh Chiang; Wang, P.

2017-01-01

Decentralized economic operation schemes have several advantages when compared with the traditional centralized management system for microgrids. Specifically, decentralized schemes are more flexible, less computationally intensive, and easier to implement without relying on communication...... costs, their power ratings, and other necessary constraints, before deciding the DG dispatch priorities and droop characteristics. The proposed scheme also allows online power reserve to be set and regulated within the microgrid. This, together with the generation cost saved, has been verified...... infrastructure. Economic operation of existing decentralized schemes is also usually achieved by either tuning the droop characteristics of distributed generators (DGs) or prioritizing their dispatch order. For the latter, an earlier scheme has tried to prioritize the DG dispatch based on their no...

Characterization of nonuniform chaos in area-preserving nonlinear maps through a continuous archetype

International Nuclear Information System (INIS)

Cerbelli, S.; Giona, M.

2008-01-01

Numerical investigations conducted over a wealth of nonlinear area-preserving smooth maps (e.g. the Standard Map) showed that these systems possess physically relevant features that are not captured by any continuous archetype of two-dimensional conservative dynamics. Among these properties are the dispersive behavior of stretch factor statistics, the multifractal character of the measure associated with invariant foliations, the sign-alternating property, accounting for the nestedly bent structure of invariant foliations, and the strict inequality between the topological entropy, h top , and the Lyapunov exponent, Λ. We refer to systems possessing all of these properties as nonuniformly chaotic. In this article, we present a globally continuous, piecewise-smooth area-preserving transformation, the toral homeomorphism H, as an archetype of nonuniformly chaotic behavior. The relatively simple structure of point set dynamics and the closed-form knowledge of the pointwise expanding and contracting invariant directions associated with H, permits to derive either analytically, or with arbitrary numerical precision, the standard chaotic properties as well as the dynamics of the physically relevant properties that define nonuniform chaos. Potentialities and limitations of the model proposed in representing geometric and statistical properties of physically relevant smooth systems are discussed in detail

On The Dynamic Analysis of Non-Uniform Beams Under Uniformly ...

African Journals Online (AJOL)

... the non-uniform continuous beam was replaced by a non-continuous (discrete) system made up of beam elements. The modified elemental and overall stiffness, and mass matrices, the elemental and overall centripetal acceleration matrices as well as the load vector were derived. Next, the Newmark's direct integration ...

Effects of a nonuniform open magnetic field on the plasma presheath

International Nuclear Information System (INIS)

Sato, Kunihiro; Miyawaki, Fujio

1991-01-01

Effects of a nonuniform magnetic field on the plasma presheath is numerically investigated using the plasma equation for a collisionless plasma with a finite-temperature particle source. The present calculation confirms that analytical solutions previously published by the authors are available over a wide range of mirror ratio. Potential drop in the presheath, which considerably depends on both the magnetic strength profile and the spatial distribution of the particle source, is remarkably increased by applying an expanding magnetic field when plasma particles are generated in the inner part of the plasma. An effect of a nonuniform magnetic field on sheath formation is also discussed by using the calculated ion distribution function. If the plasma equation has no singularity at the sheath edge, its solution satisfies the generalized Bohm criterion with the inequality sign in the expanding magnetic field. (author)

A new purely growing instability in a strongly magnetized nonuniform pair plasma

International Nuclear Information System (INIS)

Shukla, Nitin; Shukla, P.K.

2007-01-01

It is shown that a strongly magnetized nonuniform electron-positron (hereafter referred to as e-p or pair) plasma is unstable against low-frequency (in comparison with the electron gyrofrequency) electrostatic oscillations. For this purpose, a dispersion relation is derived by using the Poisson equation as well as the electron and positron continuity equations with the guiding center drifts for the electron and positron fluids. The dispersion relation admits a purely growing instability in the presence of the equilibrium density and magnetic field inhomogeneities. Physically, instability arises because of the inhomogeneous magnetic field induced differential electron and positron density fluctuations, which do not keep in phase with the electrostatic potential arising from the charge separation in our nonuniform pair plasmas

THE BEHAVIOR OF TRANSVERSE WAVES IN NONUNIFORM SOLAR FLUX TUBES. I. COMPARISON OF IDEAL AND RESISTIVE RESULTS

International Nuclear Information System (INIS)

Soler, Roberto; Terradas, Jaume; Oliver, Ramón; Goossens, Marcel

2013-01-01

Magnetohydrodynamic (MHD) waves are ubiquitously observed in the solar atmosphere. Kink waves are a type of transverse MHD waves in magnetic flux tubes that are damped due to resonant absorption. The theoretical study of kink MHD waves in solar flux tubes is usually based on the simplification that the transverse variation of density is confined to a nonuniform layer much thinner than the radius of the tube, i.e., the so-called thin boundary approximation. Here, we develop a general analytic method to compute the dispersion relation and the eigenfunctions of ideal MHD waves in pressureless flux tubes with transversely nonuniform layers of arbitrary thickness. Results for kink waves are produced and compared with fully numerical resistive MHD eigenvalue computations in the limit of small resistivity. We find that the frequency and resonant damping rate are the same in both ideal and resistive cases. The actual results for thick nonuniform layers deviate from the behavior predicted in the thin boundary approximation and strongly depend on the shape of the nonuniform layer. The eigenfunctions in ideal MHD are very different from those in resistive MHD. The ideal eigenfunctions display a global character regardless of the thickness of the nonuniform layer, while the resistive eigenfunctions are localized around the resonance and are indistinguishable from those of ordinary resistive Alfvén modes. Consequently, the spatial distribution of wave energy in the ideal and resistive cases is dramatically different. This poses a fundamental theoretical problem with clear observational consequences

Analysis of Causes of Non-Uniform Flow Distribution in Manifold Systems with Variable Flow Rate along Length

Science.gov (United States)

Zemlyanaya, N. V.; Gulyakin, A. V.

2017-11-01

The uniformity of flow distribution in perforated manifolds is a relevant task. The efficiency of water supply, sewerage and perflation systems is determined by hydraulics of the flow with a variable mass. The extensive study of versatile available information showed that achieving a uniform flow distribution through all of the outlets is almost impossible. The analysis of the studies conducted by other authors and our numerical experiments performed with the help of the software package ANSYS 16.1 were made in this work. The results allowed us to formulate the main causes of non-uniform flow distribution. We decided to suggest a hypothesis to explain the static pressure rise problem at the end of a perforated manifold.

Sharp lower bounds on the extractable randomness from non-uniform sources

NARCIS (Netherlands)

Skoric, B.; Obi, C.; Verbitskiy, E.A.; Schoenmakers, B.

2011-01-01

Extraction of uniform randomness from (noisy) non-uniform sources is an important primitive in many security applications, e.g. (pseudo-)random number generators, privacy-preserving biometrics, and key storage based on Physical Unclonable Functions. Generic extraction methods exist, using universal

Numerical analysis of blood flow in realistic arteries subjected to strong non-uniform magnetic fields

International Nuclear Information System (INIS)

Kenjeres, Sasa

2008-01-01

The paper reports on a comprehensive mathematical model for simulations of blood flow under the presence of strong non-uniform magnetic fields. The model consists of a set of Navier-Stokes equations accounting for the Lorentz and magnetisation forces, and a simplified set of Maxwell's equations (Biot-Savart/Ampere's law) for treating the imposed magnetic fields. The relevant hydrodynamic and electromagnetic properties of human blood were taken from the literature. The model is then validated for different test cases ranging from a simple cylindrical geometry to real-life right-coronary arteries in humans. The time-dependency of the wall-shear-stress for different stenosis growth rates and the effects of the imposed strong non-uniform magnetic fields on the blood flow pattern are presented and analysed. It is concluded that an imposed non-uniform magnetic field can create significant changes in the secondary flow patterns, thus making it possible to use this technique for optimisations of targeted drug delivery

Deformation of Two-Dimensional Nonuniform-Membrane Red Blood Cells Simulated by a Lattice Boltzmann Model

International Nuclear Information System (INIS)

Hua-Bing, Li; Li, Jin; Bing, Qiu

2008-01-01

To study two-dimensional red blood cells deforming in a shear Bow with the membrane nonuniform on the rigidity and mass, the membrane is discretized into equilength segments. The fluid inside and outside the red blood cell is simulated by the D2Q9 lattice Boltzmann model and the hydrodynamic forces exerted on the membrane from the inner and outer of the red blood cell are calculated by a stress-integration method. Through the global deviation from the curvature of uniform-membrane, we find that when the membrane is nonuniform on the rigidity, the deviation first decreases with the time increases and implies that the terminal profile of the red blood cell is static. To a red blood cell with the mass nonuniform on the membrane, the deviation becomes more large, and the mass distribution affects the profile of the two sides of the flattened red blood cell in a shear flow. (fundamental areas of phenomenology(including applications))

The effects of non-uniform flow velocity on vibrations of single-walled carbon nanotube conveying fluid

Energy Technology Data Exchange (ETDEWEB)

Sadeghi-Goughari, Moslem [Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Hosseini, Mohammad [Sirjan University of Technology, Sirjan (Iran, Islamic Republic of)

2015-02-15

The vibrational behavior of a viscous nanoflow-conveying single-walled carbon nanotube (SWCNT) was investigated. The nonuniformity of the flow velocity distribution caused by the viscosity of fluid and the small-size effects on the flow field was considered. Euler-Bernoulli beam model was used to investigate flow-induced vibration of the nanotube, while the non-uniformity of the flow velocity and the small-size effects of the flow field were formulated through Knudsen number (Kn), as a discriminant parameter. For laminar flow in a circular nanotube, the momentum correction factor was developed as a function of Kn. For Kn = 0 (continuum flow), the momentum correction factor was found to be 1.33, which decreases by the increase in Kn may even reach near 1 for the transition flow regime. We observed that for passage of viscous flow through a nanotube with the non-uniform flow velocity, the critical continuum flow velocity for divergence decreased considerably as opposed to those for the uniform flow velocity, while by increasing Kn, the difference between the uniform and non-uniform flow models may be reduced. In the solution part, the differential transformation method (DTM) was used to solve the governing differential equations of motion.

The effects of non-uniform flow velocity on vibrations of single-walled carbon nanotube conveying fluid

International Nuclear Information System (INIS)

Sadeghi-Goughari, Moslem; Hosseini, Mohammad

2015-01-01

The vibrational behavior of a viscous nanoflow-conveying single-walled carbon nanotube (SWCNT) was investigated. The nonuniformity of the flow velocity distribution caused by the viscosity of fluid and the small-size effects on the flow field was considered. Euler-Bernoulli beam model was used to investigate flow-induced vibration of the nanotube, while the non-uniformity of the flow velocity and the small-size effects of the flow field were formulated through Knudsen number (Kn), as a discriminant parameter. For laminar flow in a circular nanotube, the momentum correction factor was developed as a function of Kn. For Kn = 0 (continuum flow), the momentum correction factor was found to be 1.33, which decreases by the increase in Kn may even reach near 1 for the transition flow regime. We observed that for passage of viscous flow through a nanotube with the non-uniform flow velocity, the critical continuum flow velocity for divergence decreased considerably as opposed to those for the uniform flow velocity, while by increasing Kn, the difference between the uniform and non-uniform flow models may be reduced. In the solution part, the differential transformation method (DTM) was used to solve the governing differential equations of motion.

Desynchronization boost by non-uniform coordinated reset stimulation in ensembles of pulse-coupled neurons

Science.gov (United States)

Lücken, Leonhard; Yanchuk, Serhiy; Popovych, Oleksandr V.; Tass, Peter A.

2013-01-01

Several brain diseases are characterized by abnormal neuronal synchronization. Desynchronization of abnormal neural synchrony is theoretically compelling because of the complex dynamical mechanisms involved. We here present a novel type of coordinated reset (CR) stimulation. CR means to deliver phase resetting stimuli at different neuronal sub-populations sequentially, i.e., at times equidistantly distributed in a stimulation cycle. This uniform timing pattern seems to be intuitive and actually applies to the neural network models used for the study of CR so far. CR resets the population to an unstable cluster state from where it passes through a desynchronized transient, eventually resynchronizing if left unperturbed. In contrast, we show that the optimal stimulation times are non-uniform. Using the model of weakly pulse-coupled neurons with phase response curves, we provide an approach that enables to determine optimal stimulation timing patterns that substantially maximize the desynchronized transient time following the application of CR stimulation. This approach includes an optimization search for clusters in a low-dimensional pulse coupled map. As a consequence, model-specific non-uniformly spaced cluster states cause considerably longer desynchronization transients. Intriguingly, such a desynchronization boost with non-uniform CR stimulation can already be achieved by only slight modifications of the uniform CR timing pattern. Our results suggest that the non-uniformness of the stimulation times can be a medically valuable parameter in the calibration procedure for CR stimulation, where the latter has successfully been used in clinical and pre-clinical studies for the treatment of Parkinson's disease and tinnitus. PMID:23750134

GEPOIS: a two dimensional nonuniform mesh Poisson solver

International Nuclear Information System (INIS)

Quintenz, J.P.; Freeman, J.R.

1979-06-01

A computer code is described which solves Poisson's equation for the electric potential over a two dimensional cylindrical (r,z) nonuniform mesh which can contain internal electrodes. Poisson's equation is solved over a given region subject to a specified charge distribution with either Neumann or Dirichlet perimeter boundary conditions and with Dirichlet boundary conditions on internal surfaces. The static electric field is also computed over the region with special care given to normal electric field components at boundary surfaces

A Positivity-Preserving Numerical Scheme for Nonlinear Option Pricing Models

Directory of Open Access Journals (Sweden)

Shengwu Zhou

2012-01-01

Full Text Available A positivity-preserving numerical method for nonlinear Black-Scholes models is developed in this paper. The numerical method is based on a nonstandard approximation of the second partial derivative. The scheme is not only unconditionally stable and positive, but also allows us to solve the discrete equation explicitly. Monotone properties are studied in order to avoid unwanted oscillations of the numerical solution. The numerical results for European put option and European butterfly spread are compared to the standard finite difference scheme. It turns out that the proposed scheme is efficient and reliable.

Temperature dependence of o-Ps annihilation lifetime in non-uniform cylindrical pores in comparison with ETE model

Energy Technology Data Exchange (ETDEWEB)

Khaghani, Morteza, E-mail: m.khaghani@pgs.usb.ac.ir; Mehmandoost-Khajeh-Dad, Ali Akbar, E-mail: mehmandoost@phys.usb.ac.ir

2017-04-01

Highlights: • Using the well known multi-physics program COMSOL calculating o-Ps annihilation lifetime in complex geometries. • Investigation of shape non-uniformity of cylindrical pores on o-Ps annihilation lifetime. • Verifying temperature dependency of o-Ps lifetime in non-uniform cylindrical pores. • Suggesting PALS at low temperature as a method to verify pore uniformity in porous material. - Abstract: Ortho-positronium (o-Ps) annihilation lifetime was calculated in non-uniform cylinder-shaped pores by solving Schrodinger equation using a well-known multi-physics program called COMSOL. The o-Ps annihilation lifetime variation in terms of temperature was calculated on the basis of ETE model via a numerical method. The COMSOL simulations indicate that as long as the pore is uniform cylinder-shaped, the results agree with those of two-dimensional ETE model, whereas deformations in the cylinder shape (indentation or protrusion) change the temperature behavior of ETE model and, thereby, higher values are predicted for o-Ps lifetime in the pore at lower temperatures. The geometry of the non-uniform cylinder-shaped pores, which is accompanied by empirical evidence, can be used for the analysis of empirical results obtained from positron lifetime spectroscopy in different temperatures.

Impulsive response of nonuniform density liquid in a laterally excited tank

International Nuclear Information System (INIS)

Tang, Y.; Chang, Y.W.

1994-04-01

A study on the impulsive component of the dynamic response of a liquid of nonuniform density in a tank undergoing lateral base excitations is presented. The system considered is a circular cylindrical tank containing an incompressible and inviscid liquid whose density increases with the liquid depth. The density distribution along the depth can be of any arbitrary continuous or discontinuous function. In the analysis, the liquid field is divided into n layers. The thickness of the liquid layers can be different, but the density of each liquid layer is considered to be uniform and is equal to the value of the original liquid density at the mid-height of that layer. The problem is solved by the eigenfunction expansion in conjunction with the transfer matrix technique. The effect of the nonuniform liquid density on the impulsive component of the dynamic response is illustrated in a numerical example in which the linear and cosine distributions of the liquid density are assumed. The response quantities examined include the impulsive pressure, base shear and moments. The results are presented in tabular and graphical forms. It is found that the impulsive pressure distribution along the tank wall is not sensitive to the detailed distribution function of the density, and the base shear and moments for the nonuniform liquid can be estimated by assuming an equivalent uniform liquid density that preserves the total liquid weight. The effect of tank flexibility is assessed by a simple approach in which the response quantities for flexible tanks are evaluated by simplified equations

Scalable Fault-Tolerant Location Management Scheme for Mobile IP

Directory of Open Access Journals (Sweden)

JinHo Ahn

2001-11-01

Full Text Available As the number of mobile nodes registering with a network rapidly increases in Mobile IP, multiple mobility (home of foreign agents can be allocated to a network in order to improve performance and availability. Previous fault tolerant schemes (denoted by PRT schemes to mask failures of the mobility agents use passive replication techniques. However, they result in high failure-free latency during registration process if the number of mobility agents in the same network increases, and force each mobility agent to manage bindings of all the mobile nodes registering with its network. In this paper, we present a new fault-tolerant scheme (denoted by CML scheme using checkpointing and message logging techniques. The CML scheme achieves low failure-free latency even if the number of mobility agents in a network increases, and improves scalability to a large number of mobile nodes registering with each network compared with the PRT schemes. Additionally, the CML scheme allows each failed mobility agent to recover bindings of the mobile nodes registering with the mobility agent when it is repaired even if all the other mobility agents in the same network concurrently fail.

Numerical schemes for explosion hazards

International Nuclear Information System (INIS)

Therme, Nicolas

2015-01-01

'G-equation'), which is a particular Hamilton-Jacobi equation, into a transport equation so we can use the methods developed for the Euler system. A consistent gradient discretization at the faces of the mesh is needed though. For irregular meshing a 'SUSHI-scheme' technique is used. It is then adapted to cartesian grids in order to get mono-tonicity of the scheme alongside with the strong consistency of the discrete spatial operators. These joint properties insure a uniform convergence result for the upwind scheme on cartesian grids. Numerical experiments allow to check the convergence of the scheme on more irregular meshing. (author)

Canonical, stable, general mapping using context schemes.

Science.gov (United States)

Novak, Adam M; Rosen, Yohei; Haussler, David; Paten, Benedict

2015-11-15

Sequence mapping is the cornerstone of modern genomics. However, most existing sequence mapping algorithms are insufficiently general. We introduce context schemes: a method that allows the unambiguous recognition of a reference base in a query sequence by testing the query for substrings from an algorithmically defined set. Context schemes only map when there is a unique best mapping, and define this criterion uniformly for all reference bases. Mappings under context schemes can also be made stable, so that extension of the query string (e.g. by increasing read length) will not alter the mapping of previously mapped positions. Context schemes are general in several senses. They natively support the detection of arbitrary complex, novel rearrangements relative to the reference. They can scale over orders of magnitude in query sequence length. Finally, they are trivially extensible to more complex reference structures, such as graphs, that incorporate additional variation. We demonstrate empirically the existence of high-performance context schemes, and present efficient context scheme mapping algorithms. The software test framework created for this study is available from https://registry.hub.docker.com/u/adamnovak/sequence-graphs/. anovak@soe.ucsc.edu Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Analysis of single blow effectiveness in non-uniform parallel plate regenerators

DEFF Research Database (Denmark)

Jensen, Jesper Buch; Bahl, Christian Robert Haffenden; Engelbrecht, Kurt

2011-01-01

Non-uniform distributions of plate spacings in parallel plate regenerators have been found to induce loss of performance. In this paper, it has been investigated how variations of three geometric parameters (the aspect ratio, the porosity, and the standard deviation of the plate spacing) affects...

Critical opalescence of neutrons in nonuniform liquid in the gravitational field

International Nuclear Information System (INIS)

Sugakov, V.I.; Chalyj, A.V.; Chernenko, L.M.

1990-01-01

The altitude dependence of the refractive index and refractive angle of the neutron beam in a nonuniform liquid near the critical point is investigated. The neutron wave function in a passing beam as well as monochromatic transmission and reflection coefficients of neutrons are found

Analysis of the Elastic Large Deflection Behavior for Metal Plates under Nonuniformly Distributed Lateral Pressure with In-Plane Loads

Directory of Open Access Journals (Sweden)

Jeom Kee Paik

2012-01-01

Full Text Available The Galerkin method is applied to analyze the elastic large deflection behavior of metal plates subject to a combination of in-plane loads such as biaxial loads, edge shear and biaxial inplane bending moments, and uniformly or nonuniformly distributed lateral pressure loads. The motive of the present study was initiated by the fact that metal plates of ships and ship-shaped offshore structures at sea are often subjected to non-uniformly distributed lateral pressure loads arising from cargo or water pressure, together with inplane axial loads or inplane bending moments, but the current practice of the maritime industry usually applies some simplified design methods assuming that the non-uniform pressure distribution in the plates can be replaced by an equivalence of uniform pressure distribution. Applied examples are presented, demonstrating that the current plate design methods of the maritime industry may be inappropriate when the non-uniformity of lateral pressure loads becomes more significant.

Physical Limitations To Nonuniformity Correction In IR Focal Plane Arrays

Science.gov (United States)

Scribner, D. A.; Kruer, M. R.; Gridley, J. C.; Sarkady, K.

1988-05-01

Simple nonuniformity correction algorithms currently in use can be severely limited by nonlinear response characteristics of the individual pixels in an IR focal plane array. Although more complicated multi-point algorithms improve the correction process they too can be limited by nonlinearities. Furthermore, analysis of single pixel noise power spectrums usually show some level of 1 /f noise. This in turn causes pixel outputs to drift independent of each other thus causing the spatial noise (often called fixed pattern noise) of the array to increase as a function of time since the last calibration. Measurements are presented for two arrays (a HgCdTe hybrid and a Pt:Si CCD) describing pixel nonlinearities, 1/f noise, and residual spatial noise (after nonuniforming correction). Of particular emphasis is spatial noise as a function of the lapsed time since the last calibration and the calibration process selected. The resulting spatial noise is examined in terms of its effect on the NEAT performance of each array tested and comparisons are made. Finally, a discussion of implications for array developers is given.

Probing Photocurrent Nonuniformities in the Subcells of Monolithic Perovskite/Silicon Tandem Solar Cells

KAUST Repository

Song, Zhaoning

2016-11-23

Perovskite/silicon tandem solar cells with high power conversion efficiencies have the potential to become a commercially viable photovoltaic option in the near future. However, device design and optimization is challenging because conventional characterization methods do not give clear feedback on the localized chemical and physical factors that limit performance within individual subcells, especially when stability and degradation is a concern. In this study, we use light beam induced current (LBIC) to probe photocurrent collection nonuniformities in the individual subcells of perovskite/silicon tandems. The choices of lasers and light biasing conditions allow efficiency-limiting effects relating to processing defects, optical interference within the individual cells, and the evolution of water-induced device degradation to be spatially resolved. The results reveal several types of microscopic defects and demonstrate that eliminating these and managing the optical properties within the multilayer structures will be important for future optimization of perovskite/silicon tandem solar cells.

A user-driven treadmill control scheme for simulating overground locomotion.

Science.gov (United States)

Kim, Jonghyun; Stanley, Christopher J; Curatalo, Lindsey A; Park, Hyung-Soon

2012-01-01

Treadmill-based locomotor training should simulate overground walking as closely as possible for optimal skill transfer. The constant speed of a standard treadmill encourages automaticity rather than engagement and fails to simulate the variable speeds encountered during real-world walking. To address this limitation, this paper proposes a user-driven treadmill velocity control scheme that allows the user to experience natural fluctuations in walking velocity with minimal unwanted inertial force due to acceleration/deceleration of the treadmill belt. A smart estimation limiter in the scheme effectively attenuates the inertial force during velocity changes. The proposed scheme requires measurement of pelvic and swing foot motions, and is developed for a treadmill of typical belt length (1.5 m). The proposed scheme is quantitatively evaluated here with four healthy subjects by comparing it with the most advanced control scheme identified in the literature.

Effect of non-uniform surface resistance on the quality factor of superconducting niobium cavity

Science.gov (United States)

Tan, Weiwei; Lu, Xiangyang; Yang, Ziqin; Zhao, Jifei; Yang, Deyu; Yang, Yujia

2016-08-01

The formula Rs = G /Q0 is commonly used in the calculation of the surface resistance of radio frequency niobium superconducting cavities. The applying of such equation is under the assumption that surface resistance is consistent over the cavity. However, the distribution of the magnetic field varies over the cavity. The magnetic field in the equator is much higher than that in the iris. According to Thermal Feedback Theory, it leads non-uniform distribution of the density of heat flux, which results in a different temperature distribution along the cavity inter surface. The BCS surface resistance, which depends largely on the temperature, is different in each local inner surface. In this paper, the effect of surface non-uniform resistance on the quality factor has been studied, through the calculation of Q0 in the original definition of it. The results show that it is necessary to consider the non-uniform distribution of magnetic field when the accelerating field is above 20 MV/m for TESLA cavities. Also, the effect of inhomogeneity of residual resistance on the quality factor is discussed. Its distribution barely affects the quality factor.

Nonuniform Sparse Data Clustering Cascade Algorithm Based on Dynamic Cumulative Entropy

Directory of Open Access Journals (Sweden)

Ning Li

2016-01-01

Full Text Available A small amount of prior knowledge and randomly chosen initial cluster centers have a direct impact on the accuracy of the performance of iterative clustering algorithm. In this paper we propose a new algorithm to compute initial cluster centers for k-means clustering and the best number of the clusters with little prior knowledge and optimize clustering result. It constructs the Euclidean distance control factor based on aggregation density sparse degree to select the initial cluster center of nonuniform sparse data and obtains initial data clusters by multidimensional diffusion density distribution. Multiobjective clustering approach based on dynamic cumulative entropy is adopted to optimize the initial data clusters and the best number of the clusters. The experimental results show that the newly proposed algorithm has good performance to obtain the initial cluster centers for the k-means algorithm and it effectively improves the clustering accuracy of nonuniform sparse data by about 5%.

Prevention of Bridge Scour with Non-uniform Circular Piers Plane under Steady Flows

Science.gov (United States)

Chen, Hsing-Ting; Wang, Chuan-Yi

2017-04-01

River bed scour and deposit variation extremely severe because of most of rivers are steep and rapid flows, and river discharge extremely unstable and highly unsteady during different seasons in Taiwan. In addition to the obstruction of piers foundation, it causes local scour and threatens the safety of bridges. In the past, riprap, wire gabion or wrap pier works were adopted as the protections of piers foundation, but there were no effectual outcomes. The events of break off piers still happen sometimes. For example, typhoon Kalmaegi (2008) and Morakot (2009) caused heavy damages on Ho-Fon bridge in the Da-jia river and Shuang-Yuan bridge in the Kao-Ping river, respectively. Accordingly, to understand the piers scour system and propose an appropriate protection of piers foundation becomes an important topic for this study currently. This research improves the protection works of the existing uniform bridge pier (diameter D) to ensure the safety of the bridge. The non-uniform plane of circular piers (diameter D*) are placed on the top of a bridge pier foundation to reduce the down flow impacting energy and scour by its' surface roughness characteristics. This study utilize hydraulic models to simulate local scour depth and scour depth change with time for non-uniform pier diameter ratio D/D* of 0.3,0.4,0.5,0.6,0.7 and 0.8, and different type pier and initial bed level (Y) relative under the foundation top elevation under steady flows of V/Vc=0.95,0.80 and 0.65. The research results show that the scour depth increases with an increase of flow intensity (V/Vc) under different types of steady flow hydrographs. The scour depth decreases with increase of initial bed level (Y=+0.2D*,0D*and -0.2D*) relative under the foundation top elevation of the different type pier. The maximum scour depth occurred in the front of the pier for all conditions. Because of the scouring retardation by the non-uniform plane of foundation, the scour depth is reduced for the un-exposed bridge

Extension of the time-average model to Candu refueling schemes involving reshuffling

International Nuclear Information System (INIS)

Rouben, Benjamin; Nichita, Eleodor

2008-01-01

Candu reactors consist of a horizontal non-pressurized heavy-water-filled vessel penetrated axially by fuel channels, each containing twelve 50-cm-long fuel bundles cooled by pressurized heavy water. Candu reactors are refueled on-line and, as a consequence, the core flux and power distributions change continuously. For design purposes, a 'time-average' model was developed in the 1970's to calculate the average over time of the flux and power distribution and to study the effects of different refueling schemes. The original time-average model only allows treatment of simple push-through refueling schemes whereby fresh fuel is inserted at one end of the channel and irradiated fuel is removed from the other end. With the advent of advanced fuel cycles and new Candu designs, novel refueling schemes may be considered, such as reshuffling discharged fuel from some channels into other channels, to achieve better overall discharge burnup. Such reshuffling schemes cannot be handled by the original time-average model. This paper presents an extension of the time-average model to allow for the treatment of refueling schemes with reshuffling. Equations for the extended model are presented, together with sample results for a simple demonstration case. (authors)

Can preapproval jump-start the allowance market

Energy Technology Data Exchange (ETDEWEB)

Dudek, D.J.; Goffman, J.

1992-06-01

With compliance deadlines approaching in three years, utility, environmental and financial planners and their regulators are in the process of grappling with the requirements imposed, and opportunities created, by the acid rain program established under Title 4 of the Clean Air Act amendments of 1990. The novel element of the program - emissions or allowance trading through a nationwide allowance market - presents great challenges for utilities and their regulators. Perhaps the foremost challenge is establishing the allowance market. If state utility commissions subject utilities' compliance strategies to traditional after-the-fact prudence reviews, as tradition would impel them to do, the attendant regulatory risks are likely to push utilities toward more conservative compliance schemes that underuse allowance trading (as the exchange at the head of this article demonstrates). If that happens, the market will fail to develop, and its full potential for environmental benefit at least cost will go unrealized. This, in turn, is likely to strengthen the case for non-market regulatory mechanisms - a vicious circle. In this paper, the authors suggest a way out of this.

Can preapproval jump-start the allowance market?

International Nuclear Information System (INIS)

Dudek, D.J.; Goffman, J.

1992-01-01

With compliance deadlines approaching in three years, utility, environmental and financial planners and their regulators are in the process of grappling with the requirements imposed, and opportunities created, by the acid rain program established under Title 4 of the Clean Air Act amendments of 1990. The novel element of the program - emissions or allowance trading through a nationwide allowance market - presents great challenges for utilities and their regulators. Perhaps the foremost challenge is establishing the allowance market. If state utility commissions subject utilities' compliance strategies to traditional after-the-fact prudence reviews, as tradition would impel them to do, the attendant regulatory risks are likely to push utilities toward more conservative compliance schemes that underuse allowance trading (as the exchange at the head of this article demonstrates). If that happens, the market will fail to develop, and its full potential for environmental benefit at least cost will go unrealized. This, in turn, is likely to strengthen the case for non-market regulatory mechanisms - a vicious circle. In this paper, the authors suggest a way out of this

Generation of zonal magnetic fields by drift waves in a current carrying nonuniform magnetoplasma

International Nuclear Information System (INIS)

Shukla, Nitin; Shukla, P.K.

2010-01-01

It is shown that zonal magnetic fields (ZMFs) can be nonlinearly excited by incoherent drift waves (DWs) in a current carrying nonuniform magnetoplasma. The dynamics of incoherent DWs in the presence of ZMFs is governed by a wave-kinetic equation. The governing equation for ZMFs in the presence of nonlinear advection force of the DWs is obtained from the parallel component of the electron momentum equation and the Faraday law. Standard techniques are used to derive a nonlinear dispersion relation, which depicts instability via which ZMFs are excited in plasmas. ZMFs may inhibit the turbulent cross-field particle and energy transport in a nonuniform magnetoplasma.

Dynamic droop scheme considering effect of intermittent renewable energy source

DEFF Research Database (Denmark)

Wang, Yanbo; Chen, Zhe; Deng, Fujin

2016-01-01

This paper presents a dynamic droop control scheme for islanded microgrids dominated by intermittent renewable energy sources, which is able to perform desirable power sharing in the presence of renewable energy source fluctuation. First, allowable maximum power points of wind generator and PV...... flexibility and effectiveness in the presence of the renewable energy sources fluctuation....... controller of each DG unit is activated through local logic variable inferred by wind speed and solar insolation information. Simulation results are given for validating the droop control scheme. The proposed dynamic droop scheme preserves the advantage of conventional droop control method, and provides...

Mechanism and scaling for convection of isolated structures in nonuniformly magnetized plasmas

DEFF Research Database (Denmark)

Garcia, O.E.; Bian, N.H.; Naulin, V.

2005-01-01

Large-scale radial advection of isolated structures in nonuniformly magnetized plasmas is investigated. The underlying mechanism considered is due to the nonlinear evolution of interchange motions, without any presumption of plasma sheaths. Theoretical arguments supported by numerical simulations...

Wastewater diffusive dilution and sedimentation of the fine contaminated particles for nonuniform flow in open channels

OpenAIRE

Lyapin Anton; Lyapin Valery

2018-01-01

The influence of non-uniformity on mass transfer processes in open channels have been investigated under the action of urbanization factors. The study is related to the urgent problem of environmental degradation of water objects in urbanized areas. It is known that the water quality in the water objects depends on the manner in which the contaminants spread how they mix with the river water and diluted by it. The main results of the study consist of recommendations to incorporate non-uniform...

On Converting Secret Sharing Scheme to Visual Secret Sharing Scheme

Directory of Open Access Journals (Sweden)

Wang Daoshun

2010-01-01

Full Text Available Abstract Traditional Secret Sharing (SS schemes reconstruct secret exactly the same as the original one but involve complex computation. Visual Secret Sharing (VSS schemes decode the secret without computation, but each share is m times as big as the original and the quality of the reconstructed secret image is reduced. Probabilistic visual secret sharing (Prob.VSS schemes for a binary image use only one subpixel to share the secret image; however the probability of white pixels in a white area is higher than that in a black area in the reconstructed secret image. SS schemes, VSS schemes, and Prob. VSS schemes have various construction methods and advantages. This paper first presents an approach to convert (transform a -SS scheme to a -VSS scheme for greyscale images. The generation of the shadow images (shares is based on Boolean XOR operation. The secret image can be reconstructed directly by performing Boolean OR operation, as in most conventional VSS schemes. Its pixel expansion is significantly smaller than that of VSS schemes. The quality of the reconstructed images, measured by average contrast, is the same as VSS schemes. Then a novel matrix-concatenation approach is used to extend the greyscale -SS scheme to a more general case of greyscale -VSS scheme.

A joint asymmetric watermarking and image encryption scheme

Science.gov (United States)

Boato, G.; Conotter, V.; De Natale, F. G. B.; Fontanari, C.

2008-02-01

Here we introduce a novel watermarking paradigm designed to be both asymmetric, i.e., involving a private key for embedding and a public key for detection, and commutative with a suitable encryption scheme, allowing both to cipher watermarked data and to mark encrypted data without interphering with the detection process. In order to demonstrate the effectiveness of the above principles, we present an explicit example where the watermarking part, based on elementary linear algebra, and the encryption part, exploiting a secret random permutation, are integrated in a commutative scheme.

Security of helper data Schemes for SRAM-PUF in multiple enrollment scenarios

NARCIS (Netherlands)

Kusters, C.J.; Ignatenko, T.; Maes, R.; van der Sluis, E.; Selimis, G.; Willems, F.M.J.

2017-01-01

Fuzzy commitment and syndrome-based schemes are two well-known helper data schemes used to bind and generate, respectively, a secret key to/from SRAM-PUF observations. To allow the decoder to reconstruct this secret key from a new (verification) observation of an SRAM-PUF, an encoder has to generate

Two types of nonlinear wave equations for diffractive beams in bubbly liquids with nonuniform bubble number density.

Science.gov (United States)

Kanagawa, Tetsuya

2015-05-01

This paper theoretically treats the weakly nonlinear propagation of diffracted sound beams in nonuniform bubbly liquids. The spatial distribution of the number density of the bubbles, initially in a quiescent state, is assumed to be a slowly varying function of the spatial coordinates; the amplitude of variation is assumed to be small compared to the mean number density. A previous derivation method of nonlinear wave equations for plane progressive waves in uniform bubbly liquids [Kanagawa, Yano, Watanabe, and Fujikawa (2010). J. Fluid Sci. Technol. 5(3), 351-369] is extended to handle quasi-plane beams in weakly nonuniform bubbly liquids. The diffraction effect is incorporated by adding a relation that scales the circular sound source diameter to the wavelength into the original set of scaling relations composed of nondimensional physical parameters. A set of basic equations for bubbly flows is composed of the averaged equations of mass and momentum, the Keller equation for bubble wall, and supplementary equations. As a result, two types of evolution equations, a nonlinear Schrödinger equation including dissipation, diffraction, and nonuniform effects for high-frequency short-wavelength case, and a Khokhlov-Zabolotskaya-Kuznetsov equation including dispersion and nonuniform effects for low-frequency long-wavelength case, are derived from the basic set.

Some Analytical Properties of the Model for Stochastic Evolutionary Games in Finite Populations with Non-uniform Interaction Rate

International Nuclear Information System (INIS)

Quan Ji; Wang Xianjia

2013-01-01

Traditional evolutionary games assume uniform interaction rate, which means that the rate at which individuals meet and interact is independent of their strategies. But in some systems, especially biological systems, the players interact with each other discriminately. Taylor and Nowak (2006) were the first to establish the corresponding non-uniform interaction rate model by allowing the interaction rates to depend on strategies. Their model is based on replicator dynamics which assumes an infinite size population. But in reality, the number of individuals in the population is always finite, and there will be some random interference in the individuals' strategy selection process. Therefore, it is more practical to establish the corresponding stochastic evolutionary model in finite populations. In fact, the analysis of evolutionary games in a finite size population is more difficult. Just as Taylor and Nowak said in the outlook section of their paper, ''The analysis of non-uniform interaction rates should be extended to stochastic game dynamics of finite populations''. In this paper, we are exactly doing this work. We extend Taylor and Nowak's model from infinite to finite case, especially focusing on the infiuence of non-uniform connection characteristics on the evolutionary stable state of the system. We model the strategy evolutionary process of the population by a continuous ergodic Markov process. Based on the limit distribution of the process, we can give the evolutionary stable state of the system. We make a complete classification of the symmetric 2 × 2 games. For each case game, the corresponding limit distribution of the Markov-based process is given when noise intensity is small enough. In contrast with most literatures in evolutionary games using the simulation method, all our results obtained are analytical. Especially, in the dominant-case game, coexistence of the two strategies may become evolutionary stable states in our model. This result can be

Balanced Central Schemes for the Shallow Water Equations on Unstructured Grids

Science.gov (United States)

Bryson, Steve; Levy, Doron

2004-01-01

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

Using Nonuniform Fiber to Generate Slow Light via SBS

Directory of Open Access Journals (Sweden)

Wenhai Li

2008-01-01

Full Text Available The data pulse delay based on slow light induced by stimulated Brillouin scattering (SBS in a nonuniform dispersion decreasing fiber (DDF is demonstrated experimentally, and the distortions of data pulses at different beat frequencies are studied. We found that a delay exceeding a pulse width can be achieved at particular beat frequency, and the DDF has larger delay versus gain slope coefficient with much better output pulse quality than single-mode fiber.

Determination of the axial thermal neutron flux non-uniform factor in the MNSR inner irradiation capsule

International Nuclear Information System (INIS)

Khattab, K.; Ghazi, N.; Omar, H.

2007-01-01

A 3-D neutronic model, using the WIMSD4 and CITATION codes, for the Syrian Miniature Neutron source Reactor (MNSR) is used to calculate the axial thermal neutron flux non-uniform factor in the inner irradiation capsule. The calculated result is 4%. A copper wire is used to measure the axial thermal neutron flux non-uniform factor in the inner irradiation capsule to be compared with the calculated result. The measured result is 5%. Good agreement between the measured and calculated results is obtained. (author)

Determination of the axial thermal neutron flux non-uniform factor in the MNSR inner irradiation capsule

International Nuclear Information System (INIS)

Khattab, K.; Ghazi, N.; Omar, H.

2007-01-01

A 3-D neutronic model, using the WIMSD4 and CITATION codes, for the Syrian Miniature Neutron Source Reactor (MNSR) is used to calculate the axial thermal neutron flux non-uniform factor in the inner irradiation capsule. The calculated result is 4%. A copper wire is used to measure the axial thermal neutron flux non-uniform factor in the inner irradiation capsule to be compared with the calculated result. The measured result is 5%. Good agreement between the measured and calculated results is obtained

Towards the ultimate variance-conserving convection scheme

International Nuclear Information System (INIS)

Os, J.J.A.M. van; Uittenbogaard, R.E.

2004-01-01

In the past various arguments have been used for applying kinetic energy-conserving advection schemes in numerical simulations of incompressible fluid flows. One argument is obeying the programmed dissipation by viscous stresses or by sub-grid stresses in Direct Numerical Simulation and Large Eddy Simulation, see e.g. [Phys. Fluids A 3 (7) (1991) 1766]. Another argument is that, according to e.g. [J. Comput. Phys. 6 (1970) 392; 1 (1966) 119], energy-conserving convection schemes are more stable i.e. by prohibiting a spurious blow-up of volume-integrated energy in a closed volume without external energy sources. In the above-mentioned references it is stated that nonlinear instability is due to spatial truncation rather than to time truncation and therefore these papers are mainly concerned with the spatial integration. In this paper we demonstrate that discretized temporal integration of a spatially variance-conserving convection scheme can induce non-energy conserving solutions. In this paper the conservation of the variance of a scalar property is taken as a simple model for the conservation of kinetic energy. In addition, the derivation and testing of a variance-conserving scheme allows for a clear definition of kinetic energy-conserving advection schemes for solving the Navier-Stokes equations. Consequently, we first derive and test a strictly variance-conserving space-time discretization for the convection term in the convection-diffusion equation. Our starting point is the variance-conserving spatial discretization of the convection operator presented by Piacsek and Williams [J. Comput. Phys. 6 (1970) 392]. In terms of its conservation properties, our variance-conserving scheme is compared to other spatially variance-conserving schemes as well as with the non-variance-conserving schemes applied in our shallow-water solver, see e.g. [Direct and Large-eddy Simulation Workshop IV, ERCOFTAC Series, Kluwer Academic Publishers, 2001, pp. 409-287

On the Time Variation of Dust Extinction and Gas Absorption for Type Ia Supernovae Observed Through Non-uniform Interstellar Medium

Science.gov (United States)

Huang, Xiaosheng; Aldering, Gregory; Biederman, Moriah; Herger, Brendan

2018-01-01

For Type Ia supernovae (SNe Ia) observed through a non-uniform interstellar medium (ISM) in its host galaxy, we investigate whether the non-uniformity can cause observable time variations in dust extinction and in gas absorption due to the expansion of the SN photosphere with time. We show that, owing to the steep spectral index of the ISM density power spectrum, sizable density fluctuation amplitudes at the length scale of typical ISM structures (>~ 10 pc) will translate to much smaller fluctuations on the scales of a SN photosphere. Therefore the typical amplitude of time variation due to non-uniform ISM, of absorption equivalent widths and of extinction, would be small. As a result, we conclude that non-uniform ISM density should not impact cosmology measurements based on SNe Ia. We apply our predictions based on the ISM density power law power spectrum to the observations of two highly reddened SNe Ia, SN 2012cu and SN 2014J.

On the Time Variation of Dust Extinction and Gas Absorption for Type Ia Supernovae Observed through a Nonuniform Interstellar Medium

Science.gov (United States)

Huang, X.; Aldering, G.; Biederman, M.; Herger, B.

2017-11-01

For Type Ia supernovae (SNe Ia) observed through a nonuniform interstellar medium (ISM) in its host galaxy, we investigate whether the nonuniformity can cause observable time variations in dust extinction and in gas absorption due to the expansion of the SN photosphere with time. We show that, owing to the steep spectral index of the ISM density power spectrum, sizable density fluctuation amplitudes at the length scale of typical ISM structures (≳ 10 {pc}) will translate to much smaller fluctuations on the scales of an SN photosphere. Therefore, the typical amplitude of time variation due to a nonuniform ISM, of absorption equivalent widths, and of extinction, would be small. As a result, we conclude that nonuniform ISM density should not impact cosmology measurements based on SNe Ia. We apply our predictions based on the ISM density power-law power spectrum to the observations of two highly reddened SNe Ia, SN 2012cu and SN 2014J.

The influence of printing substrate on macro non-uniformity and line reproduction quality of imprints printed with electrophotographic process

Directory of Open Access Journals (Sweden)

Đorđe Vujčić

2016-12-01

Full Text Available Print quality is very important for every printing technique. It depends on many different quality attributes. This research included analysis of macro non-uniformities and line reproduction. 16 different paper substrates printed by electrophotographic process were analyzed. They were separated in two groups: coated and uncoated papers. Analysis of macro non-uniformity showed that print mottle has lower values when printed on coated papers than on uncoated papers. Line reproduction analysis showed that the toner spreaded, during melting and fixation, on line edges for both types of paper. According to these results it can be concluded that paper substrate affects the macro non-uniformity and line reproduction, thus overall print quality.

Cooperation schemes for rate enhancement in detect-and-forward relay channels

KAUST Repository

Benjillali, Mustapha

2010-05-01

To improve the spectral efficiency of "Detect-and-Forward" (DetF) half-duplex relaying in fading channels, we propose a cooperation scheme where the relay uses a modulation whose order is higher than the one at the source. In a new common framework, we show that the proposed scheme offers considerable gains - in terms of achievable information rates - compared to the conventional DetF relaying schemes for both orthogonal and non-orthogonal source/relay cooperation. This allows us to propose an adaptive cooperation scheme based on the maximization of the information rate at the destination which needs to observe only the average signal-to-noise ratios of direct and relaying links. ©2010 IEEE.

Effective electrodiffusion equation for non-uniform nanochannels.

Science.gov (United States)

Marini Bettolo Marconi, Umberto; Melchionna, Simone; Pagonabarraga, Ignacio

2013-06-28

We derive a one-dimensional formulation of the Planck-Nernst-Poisson equation to describe the dynamics of a symmetric binary electrolyte in channels whose section is nanometric and varies along the axial direction. The approach is in the spirit of the Fick-Jacobs diffusion equation and leads to a system of coupled equations for the partial densities which depends on the charge sitting at the walls in a non-trivial fashion. We consider two kinds of non-uniformities, those due to the spatial variation of charge distribution and those due to the shape variation of the pore and report one- and three-dimensional solutions of the electrokinetic equations.

Flexible RF filter using a nonuniform SCISSOR.

Science.gov (United States)

Zhuang, Leimeng

2016-03-15

This work presents a flexible radiofrequency (RF) filter using an integrated microwave photonic circuit that comprises a nonuniform side-coupled integrated spaced sequence of resonators (N-SCISSOR). The filter passband can be reconfigured by varying the N-SCISSOR parameters. When employing a dual-parallel Mach-Zechnder modulator, the filter is also able to perform frequency down-conversion. In the experiment, various filter response shapes are shown, ranging from a flat-top band-pass filter to a total opposite high-rejection (>40  dB) notch filter, with a frequency coverage of greater than two octaves. The frequency down-conversion function is also demonstrated.

Cost-Prioritized Droop Schemes for Autonomous AC Microgrids

DEFF Research Database (Denmark)

Nutkani, Inam Ullah; Loh, Poh Chiang; Wang, Peng

2015-01-01

This paper presents two cost-prioritized droop sche- mes for distributed generators (DGs) in a rural or islanded microgrid. Dispatch prioritization of the schemes allows autonomous identification of the appropriate DGs for generation, in accordance to the overall load conditions of the microgrid....

Human thermal sensation and comfort in a non-uniform environment with personalized heating.

Science.gov (United States)

Deng, Qihong; Wang, Runhuai; Li, Yuguo; Miao, Yufeng; Zhao, Jinping

2017-02-01

Thermal comfort in traditionally uniform environment is apparent and can be improved by increasing energy expenses. To save energy, non-uniform environment implemented by personalized conditioning system attracts considerable attention, but human response in such environment is unclear. To investigate regional- and whole-body thermal sensation and comfort in a cool environment with personalized heating. In total 36 subjects (17 males and 19 females) including children, adults and the elderly, were involved in our experiment. Each subject was first asked to sit on a seat in an 18°C chamber (uniform environment) for 40min and then sit on a heating seat in a 16°C chamber (non-uniform environment) for another 40min after 10min break. Subjects' regional- and whole-body thermal sensation and comfort were surveyed by questionnaire and their skin temperatures were measured by wireless sensors. We statistically analyzed subjects' thermal sensation and comfort and their skin temperatures in different age and gender groups and compared them between the uniform and non-uniform environments. Overall thermal sensation and comfort votes were respectively neutral and just comfortable in 16°C chamber with personalized heating, which were significantly higher than those in 18°C chamber without heating (pthermal sensation and comfort was consistent in subjects of different age and gender. However, adults and the females were more sensitive to the effect of personalized heating and felt cooler and less comfort than children/elderly and the males respectively. Variations of the regional thermal sensation/comfort across human body were consistent with those of skin temperature. Personalized heating significantly improved human thermal sensation and comfort in non-uniform cooler environment, probably due to the fact that it increased skin temperature. However, the link between thermal sensation/comfort and variations of skin temperature is rather complex and warrant further

A METHOD FOR EVALUATION OF NON-UNIFORM RADIANT-CONVECTIVE LOAD ON HUMAN BODY DURING MENTAL WORK

Directory of Open Access Journals (Sweden)

Lenka Prokšová Zuská

2017-10-01

Full Text Available The objective of this study was to develop a documentation for the amendment of the microclimatic part of the Czech Government Regulation, particularly in a non-uniform radiant-convective load evaluation. Changes in regulation were made based on experimental data obtained on a group of experimental individuals in a climatic chamber. One of the objectives of the climatic chamber experiments was to evaluate whether there was a possibility to use an alternative method, which utilizes a new value – stereotemperature, for the assessment. A group of 24 women was exposed to a non-uniform radiant-convective load in a climatic chamber for 1 hour during their computer work. Measurements were divided according to the globe temperature into 3 stages. The physical parameters of air were continuously measured: the air temperature, globe temperature, air velocity, radiant temperature, relative humidity, stereotemperature and physiological parameters. Thermal sensations of experimental subjects were expressed in the seven-point scale according to EN ISO 7730. The thermal sensation correlated very well with the difference of stereotemperature and the globe temperature. The stereotemperature correlated very well with the radiant temperature. In this work, the composed equations were used to develop the limit values for the thermal stress evaluation in the uniform and non-uniform thermal environment at workplaces. It is possible to determine how the body of an exposed person perceives the non-uniform climatic conditions in the indoor environment, by adding the stereotemperature to government regulations.

The design of renewable support schemes and CO_2 emissions in China

International Nuclear Information System (INIS)

Wu, Jie; Albrecht, Johan; Fan, Ying; Xia, Yan

2016-01-01

The renewable energy targets put forward by the Chinese government need comprehensive incentive schemes. This paper uses a multi-regional CGE model to evaluate two types of renewable support schemes; a subsidy scheme like a feed-in tariff (FIT) with a direct price impact for final consumers and a subsidy scheme without any price impact. We assess the CO_2 consequences of both approaches, as well as their impact on economic activity in terms of GDP, industrial structure, electricity generation structure, and regional final demand elasticities of electricity. We find that a support scheme with price impact is much more effective in reducing CO_2 emissions while the difference in GDP between the two policies is small. We estimate that the price implications of the support scheme allow for an additional emissions reduction of 113 Mt CO_2—or 0.07% of total emissions—in China during 2020–2035. The support scheme with a price impact does not lead to a negative impact on the Chinese economy although there are significant differences among regions. In addition, while the whole country faces an approximately unitary electricity elasticity demand, we find significant differences in electricity demand elasticities among Chinese regions. - Highlights: • Two types of FIT policies—with and without a price impact—are evaluated. • We assess the CO_2 emissions of both schemes and their impact on economic activity. • A support scheme with price impact is more effective in reducing CO_2 emissions. • The price impact allows for an additional reduction of 113 Mt CO_2 in China during 2020–2035. • Both of the FIT types have a very similar impact on coal consumption.

Smoothing and instability with magnetic field in a non-uniformly laser-irradiated planar target

International Nuclear Information System (INIS)

Bell, A.R.; Epperlein, E.M.

1986-01-01

Calculations are presented of the magneto-hydrodynamic response of a planar target to non-uniformities in energy deposition by a laser. The amplitude of the non-uniformities are assumed small and the equations are linearised in small perturbations about the solution for steady planar ablation driven by uniform laser energy deposition. The grad(n)xgrad(T) magnetic field source is included, along with Nernst convection and the Righi-Leduc heat flow. The magnetic field is shown to give a small increase in smoothing. A source term for magnetic field is included to simulate the effects of the Weibel instability. The instability is not strong enough to overcome the smoothing processes under the present assumptions. (author)

A blind reversible robust watermarking scheme for relational databases.

Science.gov (United States)

Chang, Chin-Chen; Nguyen, Thai-Son; Lin, Chia-Chen

2013-01-01

Protecting the ownership and controlling the copies of digital data have become very important issues in Internet-based applications. Reversible watermark technology allows the distortion-free recovery of relational databases after the embedded watermark data are detected or verified. In this paper, we propose a new, blind, reversible, robust watermarking scheme that can be used to provide proof of ownership for the owner of a relational database. In the proposed scheme, a reversible data-embedding algorithm, which is referred to as "histogram shifting of adjacent pixel difference" (APD), is used to obtain reversibility. The proposed scheme can detect successfully 100% of the embedded watermark data, even if as much as 80% of the watermarked relational database is altered. Our extensive analysis and experimental results show that the proposed scheme is robust against a variety of data attacks, for example, alteration attacks, deletion attacks, mix-match attacks, and sorting attacks.

Effects of non-uniform embedments on earthquake responses of nuclear reactor building

International Nuclear Information System (INIS)

Koyanagi, Y.; Okamoto, S.; Yoshida, K.; Inove, H.

1989-01-01

The nuclear reactor buildings have the portion embedded in soil. In the seismic design of such structures, it is essential to consider the effects of the embedment on the earthquake response. Most studies on these effects, however, assume the uniform embedment, i.e. the depth of the embedment is constant, which is convenient for the design and analysis. The behavior of the earthquake response considering the three-dimensional aspects of non-uniform embedment has not been made clear yet. In this paper, the authors evaluate the effects of the non-uniform embedment in an inclined ground surface on the earthquake response of a nuclear reactor building as illustrated. A typical PWR type reactor building is chosen as an analysis structure model. Four different types of embedment are set up for the comparison study. The three-dimensional analysis is carried out considering the geometry of embedment

Nonuniform Overlapping Method in Designing Microstrip Patch Antennas Using Genetic Algorithm Optimization

Directory of Open Access Journals (Sweden)

J. M. Jeevani W. Jayasinghe

2015-01-01

Full Text Available Genetic algorithm (GA has been a popular optimization technique used for performance improvement of microstrip patch antennas (MPAs. When using GA, the patch geometry is optimized by dividing the patch area into small rectangular cells. This has an inherent problem of adjacent cells being connected to each other with infinitesimal connections, which may not be achievable in practice due to fabrication tolerances in chemical etching. As a solution, this paper presents a novel method of dividing the patch area into cells with nonuniform overlaps. The optimized design, which is obtained by using fixed overlap sizes, shows a quad-band performance covering GSM1800, GSM1900, LTE2300, and Bluetooth bands. In contrast, use of nonuniform overlap sizes leads to obtaining a pentaband design covering GSM1800, GSM1900, UMTS, LTE2300, and Bluetooth bandswith fractional bands with of 38% due to the extra design flexibility.

Mechanical analysis of non-uniform bi-directional functionally graded intelligent micro-beams using modified couple stress theory

Science.gov (United States)

Bakhshi Khaniki, Hossein; Rajasekaran, Sundaramoorthy

2018-05-01

This study develops a comprehensive investigation on mechanical behavior of non-uniform bi-directional functionally graded beam sensors in the framework of modified couple stress theory. Material variation is modelled through both length and thickness directions using power-law, sigmoid and exponential functions. Moreover, beam is assumed with linear, exponential and parabolic cross-section variation through the length using power-law and sigmoid varying functions. Using these assumptions, a general model for microbeams is presented and formulated by employing Hamilton’s principle. Governing equations are solved using a mixed finite element method with Lagrangian interpolation technique, Gaussian quadrature method and Wilson’s Lagrangian multiplier method. It is shown that by using bi-directional functionally graded materials in nonuniform microbeams, mechanical behavior of such structures could be affected noticeably and scale parameter has a significant effect in changing the rigidity of nonuniform bi-directional functionally graded beams.

Effects of warmness and spatial nonuniformity of plasma waveguide on periodic absolute parametric instability

International Nuclear Information System (INIS)

Zaki, N.G.; Bekheit, A.H.

2011-01-01

The periodic absolute parametric instability (API) of the low-frequency oscillations excited by a monochromatic pumping field of an arbitrary amplitude in a warm 1-D (one-dimensional) nonuniform magnetoactive plasma is investigated. The separation method can be used for solving the two-fluid plasma equations describing the system. By applying this method we were able to determine the frequencies and growth rates of unstable modes and the self-consistent electric field. Plasma electrons are considered to have a thermal velocity. Different solutions for the spatial equation can be obtained the following cases: A) API in a uniform plasma, B) API in a nonuniform plasma. The latter has been studied here for two cases: B.1) the exact harmonic oscillator and B.2) the bounded harmonic oscillator (a bounded plasma). An increment has been found in the build-up of the oscillations, and it has been shown that the spatial nonuniformity of the plasma exerts the stabilizing effect on the parametric instability. A reduced growth rate of API in the warm plasma, in comparison to the cold plasma, is reported. It has also been found that the warmness of the plasma has no effect on the solution of the space part of the problem (only through the separation constant). (authors)

A disclosure scheme for protecting the victims of domestic violence.

Science.gov (United States)

Griffith, Richard

2017-06-08

Richard Griffith, Senior Lecturer in Health Law at Swansea University, explains how the Domestic Violence Disclosure Scheme aims to protect potential victims by allowing disclosure of a partner's previous crimes.

Modelling non-uniform strain distributions in aerospace composites using fibre Bragg gratings

NARCIS (Netherlands)

Rajabzadehdizaji, Aydin; Groves, R.M.; Hendriks, R.C.; Heusdens, R.; Chung, Y.; Jin, W.; Lee, B.; Canning, J.; Nakamura, K.; Yuan, L.

2017-01-01

In this paper the behaviour of fibre Bragg grating (FBG) sensors under non-uniform strain distributions was analysed. Using the fundamental matrix approach, the length of the FBG sensor was discretised, with each segment undergoing different strain values. FBG sensors that are embedded inside

Hybrid flux splitting schemes for numerical resolution of two-phase flows

Energy Technology Data Exchange (ETDEWEB)

Flaatten, Tore

2003-07-01

This thesis deals with the construction of numerical schemes for approximating. solutions to a hyperbolic two-phase flow model. Numerical schemes for hyperbolic models are commonly divided in two main classes: Flux Vector Splitting (FVS) schemes which are based on scalar computations and Flux Difference Splitting (FDS) schemes which are based on matrix computations. FVS schemes are more efficient than FDS schemes, but FDS schemes are more accurate. The canonical FDS schemes are the approximate Riemann solvers which are based on a local decomposition of the system into its full wave structure. In this thesis the mathematical structure of the model is exploited to construct a class of hybrid FVS/FDS schemes, denoted as Mixture Flux (MF) schemes. This approach is based on a splitting of the system in two components associated with the pressure and volume fraction variables respectively, and builds upon hybrid FVS/FDS schemes previously developed for one-phase flow models. Through analysis and numerical experiments it is demonstrated that the MF approach provides several desirable features, including (1) Improved efficiency compared to standard approximate Riemann solvers, (2) Robustness under stiff conditions, (3) Accuracy on linear and nonlinear phenomena. In particular it is demonstrated that the framework allows for an efficient weakly implicit implementation, focusing on an accurate resolution of slow transients relevant for the petroleum industry. (author)

Effects of Warmness and Spatial Nonuniformity of the Plasma Waveguide on Periodic Absolute Parametric Instability

International Nuclear Information System (INIS)

Zaki, N.G.; Bekheit, A.H.

2011-01-01

The periodic absolute parametric instability (API) of the low-frequency oscillations excited by a monochromatic pumping field of arbitrary amplitude in a warm I-D nonuniform magneto active plasma is investigated. One can use the separation method to solve the two-fluid plasma equations which describe the system. The method used enables us to determine the frequencies and growth rates of unstable modes and the self-consistent electric field. Plasma electrons are considered to have a thermal velocity. One can examine different solutions for the spatial equation in the following cases: A) API in uniform Plasma B) API in nonuniform plasma, we study this case for two variants: B.1) Exact harmonic oscillator and B.2) Bounded harmonic oscillator (bounded plasma). Increment is found in the buildup of the oscillations, and it is shown that the spatial nonuniformity of the plasma exerts a stabilizing effect on the parametric instability. It is shown that the growth rate of API in warm plasma is reduced compared to cold plasma. It is found also that the warmness of the plasma has no effect on the solution of the space part of the problem ( only through the separation constant )

Design of Chebychev’s Low Pass Filters Using Nonuniform Transmission Lines

Directory of Open Access Journals (Sweden)

Said Attamimi

2016-03-01

Full Text Available Transmission lines are utilized in many applications to convey energy as well as information. Nonuniform transmission lines (NTLs are obtained through variation of the characteristic quantities along the axial direction. Such NTLs can be used to design network elements, like matching circuits, delay equalizers, filters, VLSI interconnections, etc. In this work, NTLs were analyzed with a numerical method based on the implementation of method of moment. In order to approximate the voltage and current distribution along the transmission line, a sum of basis functions with unknown amplitudes was introduced. As basis function, a constant function was used. In this work, we observed several cases such as lossless and lossy uniform transmission lines with matching and arbitrary load. These cases verified the algorithm developed in this work. The second example consists of nonuniform transmission lines in the form of abruptly changing transmission lines. This structure was used to design a Chebychev’s low pass filter. The calculated reflection and transmission factors of the filters showed some coincidences with the measurements.

Gravitational Influences on Flame Propagation through Non-Uniform, Premixed Gas Systems

Science.gov (United States)

Miller, Fletcher J.; Easton, John; Ross, Howard D.; Marchese, Anthony; Perry, David; Kulis, Michael

2001-01-01

Flame propagation through non-uniformly premixed (or layered) gases has importance both in useful combustion systems and in unintentional fires. As summarized previously, non-uniform premixed gas combustion receives scant attention compared to the more usual limiting cases of diffusion or uniformly premixed flames, especially regarding the role gravity plays. This paper summarizes our progress on furthering the knowledge of layered combustion, in which a fuel concentration gradient exists normal to the direction of flame spread. We present experimental and numerical results for flame spread through propanol-air layers formed near the flash point temperature (25 C) or near the stoichiometric temperature (33 C). Both the model and experimental results show that the removal of gravity results in a faster spreading flame, by as much as 80% depending on conditions. This is exactly the opposite effect as that predicted by an earlier model reported. We also found that having a gallery lid results in faster flame spread, an effect more pronounced at normal gravity, demonstrating the importance of enclosure geometry. Also reported here is the beginning of our spectroscopic measurements of fuel vapor.

Numerical research on natural convection in molten salt reactor with non-uniformly distributed volumetric heat generation

International Nuclear Information System (INIS)

Qian Libo; Qiu Suizheng; Zhang Dalin; Su Guanghui; Tian Wenxi

2010-01-01

Molten salt reactor is one of the six Generation IV systems capable of breeding and transmutation of actinides and long-lived fission products, which uses the liquid molten salt as the fuel solvent, coolant and heat generation simultaneously. The present work presents a numerical investigation on natural convection with non-uniform heat generation through which the heat generated by the fluid fuel is removed out of the core region when the reactor is under post-accident condition or zero-power condition. The two-group neutron diffusion equation is applied to calculated neutron flux distribution, which leads to non-uniform heat generation. The SIMPLER algorithm is used to calculate natural convective heat transfer rate with isothermal or adiabatic rigid walls. These two models are coupled through the temperature field and heat sources. The peculiarities of natural convection with non-uniform heat generation are investigated in a range of Ra numbers (10 3 ∼ 10 7 ) for the laminar regime of fluid motion. In addition, the numerical results are also compared with those containing uniform heat generation.

A numerical scheme for the one-dimensional pressureless gases system

OpenAIRE

Boudin , Laurent; Mathiaud , Julien

2012-01-01

International audience; In this work, we investigate the numerical solving of the one-dimensional pressureless gases system. After briefly recalling the mathematical framework of the duality solutions introduced by Bouchut and James, we point out that the upwind scheme for the density and momentum does not satisfy the one-sided Lipschitz (OSL) condition on the expansion rate required for the duality solutions. Then we build a diffusive scheme which allows to recover the OSL condition by follo...

On applications of chimera grid schemes to store separation

Science.gov (United States)

Cougherty, F. C.; Benek, J. A.; Steger, J. L.

1985-01-01

A finite difference scheme which uses multiple overset meshes to simulate the aerodynamics of aircraft/store interaction and store separation is described. In this chimera, or multiple mesh, scheme, a complex configuration is mapped using a major grid about the main component of the configuration, and minor overset meshes are used to map each additional component such as a store. As a first step in modeling the aerodynamics of store separation, two dimensional inviscid flow calculations were carried out in which one of the minor meshes is allowed to move with respect to the major grid. Solutions of calibrated two dimensional problems indicate that allowing one mesh to move with respect to another does not adversely affect the time accuracy of an unsteady solution. Steady, inviscid three dimensional computations demonstrate the capability to simulate complex configurations, including closely packed multiple bodies.

A national quality control scheme for serum HGH assays

International Nuclear Information System (INIS)

Hunter, W.M.; McKenzie, I.

1979-01-01

In the autumn of 1975 the Supraregional Assay Service established a Quality Control Sub-Committee and the intra-laboratory QC Scheme for Growth Hormone (HGH) assays which is described here has served, in many respects, as a pilot scheme for protein RIA. Major improvements in accuracy, precision and between-laboratory agreement can be brought about by intensively interactive quality control schemes. A common standard is essential and should consist of ampoules used for one or only a small number of assays. Accuracy and agreement were not good enough to allow the overall means to serve as target values but a group of 11 laboratories were sufficiently accurate to provide a 'reference group mean' to so serve. Gross non-specificity was related to poor assay design and was quickly eliminated. Within-laboratory between-batch variability was much worse than that normally claimed for simple protein hormone RIA. A full report on this Scheme will appear shortly in Annals of Clinical Biochemistry. (Auth.)

Magneto-acoustic resonance in a non-uniform current carrying plasma column

OpenAIRE

Vaclavik, J.

2017-01-01

The forced radial magneto-acoustic oscillations in a plasma column with nonuniform mass density and temperature are investigated. It turns out that the oscillations have a resonant character similar to that of the magneto-acoustic oscillations in a uniform plasma column. The properties of the axial and azimuthal components of the oscillating magnetic field are discussed in detail

Non-uniform approximations for sums of discrete m-dependent random variables

OpenAIRE

Vellaisamy, P.; Cekanavicius, V.

2013-01-01

Non-uniform estimates are obtained for Poisson, compound Poisson, translated Poisson, negative binomial and binomial approximations to sums of of m-dependent integer-valued random variables. Estimates for Wasserstein metric also follow easily from our results. The results are then exemplified by the approximation of Poisson binomial distribution, 2-runs and $m$-dependent $(k_1,k_2)$-events.

Selective catalytic reduction converter design: The effect of ammonia nonuniformity at inlet

International Nuclear Information System (INIS)

Paramadayalan, Thiyagarajan; Pant, Atul

2013-01-01

A three-dimensional CFD model of SCR converter with detailed chemistry is developed. The model is used to study the effects of radial variation in inlet ammonia profile on SCR emission performance at different temperatures. The model shows that radial variation in inlet ammonia concentration affects the SCR performance in the operating range of 200-400 .deg. C. In automotive SCR systems, ammonia is non-uniformly distributed due to evaporation/reaction of injected urea, and using a 1D model or a 3D model with flat ammonia profile at inlet for these conditions can result in erroneous emission prediction. The 3D SCR model is also used to study the effect of converter design parameters like inlet cone angle and monolith cell density on the SCR performance for a non-uniform ammonia concentration profile at the inlet. The performance of SCR is evaluated using DeNO x efficiency and ammonia slip

Linearization of Nonautonomous Impulsive System with Nonuniform Exponential Dichotomy

Directory of Open Access Journals (Sweden)

Yongfei Gao

2014-01-01

Full Text Available This paper gives a version of Hartman-Grobman theorem for the impulsive differential equations. We assume that the linear impulsive system has a nonuniform exponential dichotomy. Under some suitable conditions, we proved that the nonlinear impulsive system is topologically conjugated to its linear system. Indeed, we do construct the topologically equivalent function (the transformation. Moreover, the method to prove the topological conjugacy is quite different from those in previous works (e.g., see Barreira and Valls, 2006.

Scheme for teleportation of unknown states of trapped ion

Institute of Scientific and Technical Information of China (English)

Chen Mei-Feng; Ma Song-She

2008-01-01

A scheme is presented for teleporting an unknown state in a trapped ion system.The scheme only requires a single laser beam.It allows the trap to be in any state with a few phonons,e.g.a thermal motion.Furthermore,it works in the regime,where the Rabi frequency of the laser is on the order of the trap frequency.Thus,the teleportation speed is greatly increased,which is important for decreasing the decoherence effect.This idea can also be used to teleport an unknown ionic entangled state.

Tunable pinning effects produced by non-uniform antidot arrays in YBCO thin films

Energy Technology Data Exchange (ETDEWEB)

George, J.; Jones, A.; Al-Qurainy, M. [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW (Australia); Fedoseev, S.A. [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW (Australia); Centre for Medical Radiation Physics, University of Wollongong, NSW (Australia); Rosenfeld, A. [Centre for Medical Radiation Physics, University of Wollongong, NSW (Australia); Pan, A.V. [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW (Australia); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation)

2017-04-15

Uniform, graded and spaced arrays of 3 μm triangular antidots in pulsed laser deposited YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO) superconducting thin films are compared by examining the improvements in the critical current density J{sub c} they produced. The comparison is made to establish the role of their lithographically defined (non-)uniformity and the effectiveness to control and/or enhance the critical current density. It is found that almost all types of non-uniform arrays, including graded ones enhance J{sub c} over the broad applied magnetic field and temperature range due to the modified critical state. Whereas uniform arrays of antidots either reduce or produce no effect on J{sub c} compared to the original (as-deposited) thin films. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Non-uniform velocity profile mechanism for flame stabilization in a porous radiant burner

Energy Technology Data Exchange (ETDEWEB)

Catapan, R.C.; Costa, M. [Mechanical Engineering Department, Instituto Superior Tecnico, Technical University of Lisbon, Avenida Rovisco Pais, 1049-001 Lisbon (Portugal); Oliveira, A.A.M. [Mechanical Engineering Department, Federal University of Santa Catarina, Campus Universitario Professor Joao David Ferreira Lima, 88040-900 Florianopolis, SC (Brazil)

2011-01-15

Industrial processes where the heating of large surfaces is required lead to the possibility of using large surface porous radiant burners. This causes additional temperature uniformity problems, since it is increasingly difficult to evenly distribute the reactant mixture over a large burner surface while retaining its stability and keeping low pollutant emissions. In order to allow for larger surface area burners, a non-uniform velocity profile mechanism for flame stabilization in a porous radiant burner using a single large injection hole is proposed and analyzed for a double-layered burner operating in open and closed hot (laboratory-scale furnace, with temperature-controlled, isothermal walls) environments. In both environments, local mean temperatures within the porous medium have been measured. For lower reactant flow rate and ambient temperature the flame shape is conical and anchored at the rim of the injection hole. As the volumetric flow rate or furnace temperature is raised, the flame undergoes a transition to a plane flame stabilized near the external burner surface. However, the stability range envelope remains the same in both regimes. (author)

Nonuniform nuclear structures and QPOs in giant flares

International Nuclear Information System (INIS)

Sotani, Hajime

2012-01-01

We show that the shear modes in the neutron star crust are quite sensitive to the existence of nonuniform nuclear structures, the so-called “pasta”. Due to the existence of pasta phase, the frequencies of shear modes are reduced. Since the torsional shear frequencies depend strongly on the structure of pasta phase, through the observations of stellar oscillations, one can probe the pasta structure in the crust. Additionally, considering the effect of pasta phase, we show the possibility to explain all the observed frequencies in the SGR 1806-20 with using only crust torsional oscillations.

Nonuniform nuclear structures and QPOs in giant flares

Energy Technology Data Exchange (ETDEWEB)

Sotani, Hajime [Division of Theoretical Astronomy, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

2012-11-12

We show that the shear modes in the neutron star crust are quite sensitive to the existence of nonuniform nuclear structures, the so-called 'pasta'. Due to the existence of pasta phase, the frequencies of shear modes are reduced. Since the torsional shear frequencies depend strongly on the structure of pasta phase, through the observations of stellar oscillations, one can probe the pasta structure in the crust. Additionally, considering the effect of pasta phase, we show the possibility to explain all the observed frequencies in the SGR 1806-20 with using only crust torsional oscillations.

A Test of Thick-Target Nonuniform Ionization as an Explanation for Breaks in Solar Flare Hard X-Ray Spectra

Science.gov (United States)

Holman, gordon; Dennis Brian R.; Tolbert, Anne K.; Schwartz, Richard

2010-01-01

Solar nonthermal hard X-ray (HXR) flare spectra often cannot be fitted by a single power law, but rather require a downward break in the photon spectrum. A possible explanation for this spectral break is nonuniform ionization in the emission region. We have developed a computer code to calculate the photon spectrum from electrons with a power-law distribution injected into a thick-target in which the ionization decreases linearly from 100% to zero. We use the bremsstrahlung cross-section from Haug (1997), which closely approximates the full relativistic Bethe-Heitler cross-section, and compare photon spectra computed from this model with those obtained by Kontar, Brown and McArthur (2002), who used a step-function ionization model and the Kramers approximation to the cross-section. We find that for HXR spectra from a target with nonuniform ionization, the difference (Delta-gamma) between the power-law indexes above and below the break has an upper limit between approx.0.2 and 0.7 that depends on the power-law index delta of the injected electron distribution. A broken power-law spectrum with a. higher value of Delta-gamma cannot result from nonuniform ionization alone. The model is applied to spectra obtained around the peak times of 20 flares observed by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI from 2002 to 2004 to determine whether thick-target nonuniform ionization can explain the measured spectral breaks. A Monte Carlo method is used to determine the uncertainties of the best-fit parameters, especially on Delta-gamma. We find that 15 of the 20 flare spectra require a downward spectral break and that at least 6 of these could not be explained by nonuniform ionization alone because they had values of Delta-gamma with less than a 2.5% probability of being consistent with the computed upper limits from the model. The remaining 9 flare spectra, based on this criterion, are consistent with the nonuniform ionization model.

A privacy authentication scheme based on cloud for medical environment.

Science.gov (United States)

Chen, Chin-Ling; Yang, Tsai-Tung; Chiang, Mao-Lun; Shih, Tzay-Farn

2014-11-01

With the rapid development of the information technology, the health care technologies already became matured. Such as electronic medical records that can be easily stored. However, how to get medical resources more convenient is currently concerning issue. In spite of many literatures discussed about medical systems, these literatures should face many security challenges. The most important issue is patients' privacy. Therefore, we propose a privacy authentication scheme based on cloud environment. In our scheme, we use mobile device's characteristics, allowing peoples to use medical resources on the cloud environment to find medical advice conveniently. The digital signature is used to ensure the security of the medical information that is certified by the medical department in our proposed scheme.

Improvement of the mining technology with the ring movement scheme of the haul trucks

Directory of Open Access Journals (Sweden)

Slobodyanyuk R.V.

2016-04-01

Full Text Available The article describes the designed technology that allows to expand the use of the haul truck ring movement scheme and to reduce the share of an empty run time in the transportation cycle. A preliminary calculation of the efficiency of its usage has allowed to confirm the main advantages of this scheme over the existing one as follows: reducing the required number of transport for the needs of open-pit mine operation by increasing the productivity of mining trucks; decreasing the transport operating costs (some part of an empty truck movement occurs when the engine is switched off; dropping the probability of accidents (reduced a number of the counter transport maneuvers. The calculation showed the regularity of changes in the efficiency using the alternative scheme in relation to the basic one, which reflecting significantly higher effectiveness in situations with a smaller distance between the empty run sites of the ring scheme.

Short-run allocation of emissions allowances and long-term goals for climate policy

NARCIS (Netherlands)

Zetterberg, Lars; Wråke, Markus; Sterner, Thomas; Fischer, Carolyn; Burtraw, Dallas

We use economic analysis to evaluate grandfathering, auctioning, and benchmarking approaches for allocation of emissions allowances and then discuss practical experience from European and American schemes. In principle, auctions are superior from the viewpoints of efficiency, fairness, transparency,

Development of Mycoplasma synoviae (MS) core genome multilocus sequence typing (cgMLST) scheme.

Science.gov (United States)

Ghanem, Mostafa; El-Gazzar, Mohamed

2018-05-01

Mycoplasma synoviae (MS) is a poultry pathogen with reported increased prevalence and virulence in recent years. MS strain identification is essential for prevention, control efforts and epidemiological outbreak investigations. Multiple multilocus based sequence typing schemes have been developed for MS, yet the resolution of these schemes could be limited for outbreak investigation. The cost of whole genome sequencing became close to that of sequencing the seven MLST targets; however, there is no standardized method for typing MS strains based on whole genome sequences. In this paper, we propose a core genome multilocus sequence typing (cgMLST) scheme as a standardized and reproducible method for typing MS based whole genome sequences. A diverse set of 25 MS whole genome sequences were used to identify 302 core genome genes as cgMLST targets (35.5% of MS genome) and 44 whole genome sequences of MS isolates from six countries in four continents were used for typing applying this scheme. cgMLST based phylogenetic trees displayed a high degree of agreement with core genome SNP based analysis and available epidemiological information. cgMLST allowed evaluation of two conventional MLST schemes of MS. The high discriminatory power of cgMLST allowed differentiation between samples of the same conventional MLST type. cgMLST represents a standardized, accurate, highly discriminatory, and reproducible method for differentiation between MS isolates. Like conventional MLST, it provides stable and expandable nomenclature, allowing for comparing and sharing the typing results between different laboratories worldwide. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Thermal stability improvement of a multiple finger power SiGe heterojunction bipolar transistor under different power dissipations using non-uniform finger spacing

International Nuclear Information System (INIS)

Chen Liang; Zhang Wan-Rong; Jin Dong-Yue; Shen Pei; Xie Hong-Yun; Ding Chun-Bao; Xiao Ying; Sun Bo-Tao; Wang Ren-Qing

2011-01-01

A method of non-uniform finger spacing is proposed to enhance thermal stability of a multiple finger power SiGe heterojunction bipolar transistor under different power dissipations. Temperature distribution on the emitter fingers of a multi-finger SiGe heterojunction bipolar transistor is studied using a numerical electro-thermal model. The results show that the SiGe heterojunction bipolar transistor with non-uniform finger spacing has a small temperature difference between fingers compared with a traditional uniform finger spacing heterojunction bipolar transistor at the same power dissipation. What is most important is that the ability to improve temperature non-uniformity is not weakened as power dissipation increases. So the method of non-uniform finger spacing is very effective in enhancing the thermal stability and the power handing capability of power device. Experimental results verify our conclusions. (interdisciplinary physics and related areas of science and technology)

On the burnout in annular channels at non-uniform heat release distribution in length

International Nuclear Information System (INIS)

Ornatskij, A.P.; Chernobaj, V.A.; Vasil'ev, A.F.; Struts, G.V.

1982-01-01

The effect of axial heat release non-uniformity on the conditions of the burnout in annular channels is investigated. The investigation is carried out in annular channels with different laws of heat flux density distribution by channel length. The heat release non-uniformity coefficient was varied from 4.4 to 10, the pressure from 9.8 to 17.6 MPa, mass rate from 500 to 1700 kg (m 2 xS), liquid temperature (chemically desalted water) at the channel inlet constituted 30-300 deg C. The experiments have been performed at the test bench with a closed circulation circuit. The data obtained testify to the fact that under non-uniform heat release the influence of main operating parameters on the value of critical power is of the same character as under uniform heat release. The character of wall temperature variation by channel length before the burnout is determined by the form of heat supply temperature profile. The temperature maximum is observed in the region lying behind the cross section with maximum heat flux. The conclusion is drawn that the dominant influence on the position of the cross section in which the burnout arises is exerted by the form of heat flux density distribution by length. Independently of this distribution form the burnout developes when the vapour content near the wall reaches a limiting value

Strength analysis of fast gas cooled reactor fuel element in conditions of fuel-cladding interraction and non-uniform azimuthal heating

International Nuclear Information System (INIS)

Kulikov, I.S.; Tverkovkin, B.E.

1984-01-01

The technique and the PRORT mathematical program in FORTRAN language for determining mechanical properties of a fuel element with motionless fuel-cladding interaction taking into account circular temperature non-uniformity in gas-cooled fast reactor conditions are proposed. The calculation results of the fuel element of dissociating gas cooled fast reactor are presented for seven cross-sections over the height of the core. The obtained data testify to appreciable swelling of Cr16Ni15Mo3Nb steel fuel cladding in the conditions of dissociating gas cooled fast reactor through the allowance for the effect of stresses on this essential parameter shows, that its value is lower in comparison with swelling, wherein stresses are not taken into account

Sparse grid techniques for particle-in-cell schemes

Science.gov (United States)

Ricketson, L. F.; Cerfon, A. J.

2017-02-01

We propose the use of sparse grids to accelerate particle-in-cell (PIC) schemes. By using the so-called ‘combination technique’ from the sparse grids literature, we are able to dramatically increase the size of the spatial cells in multi-dimensional PIC schemes while paying only a slight penalty in grid-based error. The resulting increase in cell size allows us to reduce the statistical noise in the simulation without increasing total particle number. We present initial proof-of-principle results from test cases in two and three dimensions that demonstrate the new scheme’s efficiency, both in terms of computation time and memory usage.

An Energy-aware Routing Scheme in Delay Tolerant Mobile Sensor Networking

Directory of Open Access Journals (Sweden)

Zhe Chen

2014-08-01

Full Text Available In Delay Tolerant Mobile Sensor Networking (DTMSN, mobile sensor nodes are usually limited to their energy capacity, one important concern in routing design of DTMSN is energy consumption. This paper presents a number of variations of the Epidemic Routing Protocol (ERP to extend the DTMSN lifetime. It introduces the analytical model for ERP, after introducing the concepts behind the Target Delivery Probability and Minimum Delivery Probability, it defines the network lifetime. In this paper, it firstly studies many variations of the Epidemic Routing Protocol to extend the lifetime of the DTMSN. Secondly, based on the Epidemic Routing Protocol, three schemes are introduced. Those schemes rely on the limiting the times of message allowed for propagation (LT scheme, directly controlling the number of the copies (LC scheme, split the copies to the residual energies of the nodes (LE scheme. Finally, with the experiment and the validation of the simulation, the LE scheme can significantly maximize the lifetime of DTMSN, because it minimizes the number of copies and that shifts the generation of the copies to the nodes with larger residual energy.

Absolute parametric instability of low frequency waves in a 2-D nonuniform anisotropic warm plasma

International Nuclear Information System (INIS)

Zaki, N.G.

2004-01-01

Using the separation method, the problem of absolute parametric instability (API) of electrostatic waves in magnetized pumped warm plasma is investigated. In this case the effect of static strong magnetic field is considered. The problem of strong magnetic field is solved in 2-D nonuniform plane plasma. The equations which describe the spatial part of the electric potential are obtained. Also the growth rates and conditions of the parametric instability for periodic cases are obtained. It is found that the spatial nonuniformity of the plasma exerts a stabilizing effect on the API. It is shown that the growth rates of periodic and aperiodic API in warm plasma are reduced in comparison with a cold plasma case

Novel scheme for simple label-swapping employing XOR logic in an integrated interferometric wavelength converter

DEFF Research Database (Denmark)

Fjelde, Tina; Kloch, Allan; Wolfson, David

2001-01-01

We present a novel scheme for all-optical label swapping that relies on logic exclusive-OR (XOR) in an integrated SOA-based Michelson interferometer. The scheme allows simple, efficient and mechanically stable operation, while relaxing the requirements on packet format and simplifying switch...

Design of multiplier-less sharp non-uniform cosine modulated filter banks for efficient channelizers in software defined radio

Directory of Open Access Journals (Sweden)

Shaeen Kalathil

2016-03-01

Full Text Available Forthcoming software defined radios require filter banks which satisfy stringent specifications efficiently with low implementation complexity. Cosine modulated filter banks (CMFB have simple and efficient design procedure. The different wireless standards have different channel spacing or bandwidths and hence demand non-uniform decomposition of subbands. The non-uniform CMFB can be obtained from a uniform CMFB in a simple and efficient approach by merging the adjacent channels of the uniform CMFB. Very narrow transition width filters with low complexity can be achieved using frequency response masking (FRM filter as prototype filter. The complexity is further reduced by the multiplier-less realization of filter banks in which the least number of signed power of two (SPT terms is achieved by representing the filter coefficients using canonic signed digit (CSD representation and then optimizing using suitable modified meta-heuristic algorithms. Hybrid meta-heuristic algorithms are used in this paper. A hybrid algorithm combines the qualities of two meta-heuristic algorithms and results in improved performances with low implementation complexity. Highly frequency selective filter banks characterized by small passband ripple, narrow transition width and high stopband attenuation with non-uniform decomposition of subbands can be designed with least the implementation complexity, using this approach. A digital channelizer can be designed for SDR implementations, using the proposed approach. In this paper, the non-uniform CMFB is designed for various existing wireless standards.

Security Analysis and Improvement of an Anonymous Authentication Scheme for Roaming Services

Directory of Open Access Journals (Sweden)

Youngsook Lee

2014-01-01

Full Text Available An anonymous authentication scheme for roaming services in global mobility networks allows a mobile user visiting a foreign network to achieve mutual authentication and session key establishment with the foreign-network operator in an anonymous manner. In this work, we revisit He et al.’s anonymous authentication scheme for roaming services and present previously unpublished security weaknesses in the scheme: (1 it fails to provide user anonymity against any third party as well as the foreign agent, (2 it cannot protect the passwords of mobile users due to its vulnerability to an offline dictionary attack, and (3 it does not achieve session-key security against a man-in-the-middle attack. We also show how the security weaknesses of He et al.’s scheme can be addressed without degrading the efficiency of the scheme.

Effect of disjoining pressure in a thin film equation with non-uniform forcing

KAUST Repository

MOULTON, D. E.; LEGA, J.

2013-01-01

We explore the effect of disjoining pressure on a thin film equation in the presence of a non-uniform body force, motivated by a model describing the reverse draining of a magnetic film. To this end, we use a combination of numerical investigations

Concentration polarization effects on the macromolecular transport in the presence of non-uniform magnetic field: A numerical study using a lumen-wall model

Energy Technology Data Exchange (ETDEWEB)

Mohammadpourfard, M., E-mail: Mohammadpour@azaruniv.edu [Department of Mechanical Engineering, Azarbaijan Shahid Madani University, Tabriz 53751-71379 (Iran, Islamic Republic of); Aminfar, H., E-mail: hh_aminfar@tabrizu.ac.ir [Faculty of Mechanical Engineering, University of Tabriz, Tabriz (Iran, Islamic Republic of); Khajeh, K., E-mail: khajeh.k.2005@gmail.com [Faculty of Mechanical Engineering, University of Tabriz, Tabriz (Iran, Islamic Republic of)

2014-04-01

In this paper, the concentration polarization phenomena in a two dimensional tube under steady state conditions containing ferrofluid (blood and 4 vol% Fe{sub 3}O{sub 4}) is reported in the presence of non-uniform magnetic field. Lumen-wall model has been used for solving the mass transport equation. Hemodynamics parameters such as flow rate, viscosity, wall shear stress (WSS) and the macromolecules surface concentration which accumulate on the blood vessel wall, influenced the formation and progression of atherosclerosis disease. Effective parameters on the low density lipoprotein (LDL) surface concentration (LSC) such as: the wall filtration velocity, inlet Reynolds number and WSS under applied non-uniform magnetic field have been examined. Numerical solution of governing equations of the flow field have been obtained by using the single-phase model and the control volume technique. Magnetic field is generated by an electric current going through a thin and straight wire oriented perpendicular to the tube. Results show WSS in the vicinity of magnetic field source increased and LSC decreased along the wall. - Highlights: • In this paper the concentration polarization phenomena of blood flow is reported in the presence of non-uniform magnetic field. • In presence of non-uniform magnetic field LSC will decrease along the wall due to the increasing the velocity gradients near the magnetic source. • When non-uniform magnetic field intensity increases, LSC along the wall becomes lower. • Non-uniform magnetic field can affects the flow more in low Reynolds numbers.

Non-uniformly sampled grids in double pole coordinate system for freeform reflector construction

Science.gov (United States)

Ma, Donglin; Pacheco, Shaun; Feng, Zexin; Liang, Rongguang

2015-08-01

We propose a new method to design freeform reflectors by nonuniformly sampling the source intensity distribution in double pole coordinate system. In double pole coordinate system, there is no pole for the whole hemisphere because both poles of the spherical coordinate system are moved to southernmost point of the sphere and overlapped together. With symmetric definition of both angular coordinates in the modified double pole coordinate system, a better match between the source intensity distribution and target irradiance distribution can be achieved for reflectors with large acceptance solid angle, leading to higher light efficiency and better uniformity on the target surface. With non-uniform sampling of the source intensity, we can design circular freeform reflector to obtain uniform rectangular illumination pattern. Aided by the feedback optimization, the freeform reflector can achieve the collection efficiency for ideal point source over 0.7 and relative standard deviation (RSD) less than 0.1.

Dimensional renormalization and comparison of renormalization schemes in quantum electrodynamics

International Nuclear Information System (INIS)

Coquereaux, R.

1979-02-01

The method of dimensional renormalization as applied to quantum electrodynamics is discussed. A general method is given which allows one to compare the various quantities like coupling constants and masses that appear in different renormalization schemes

ROC evaluation of SPECT myocardial lesion detectability with and without single iteration non-uniform Chang attenuation compensation using an anthropomorphic female phantom

International Nuclear Information System (INIS)

Jang, S.; Jaszczak, R.J.; Duke Univ. Medical Center, Durham, NC; Gilland, D.R.; Turkington, T.G.; Coleman, R.E.; Tsui, B.M.W.; Metz, C.E.

1998-01-01

The purpose of this work was to evaluate lesion detectability with and without nonuniform attenuation compensation (AC) in myocardial perfusion SPECT imaging in women using an anthropomorphic phantom and receiver operating characteristics (ROC) methodology. Breast attenuation causes artifacts in reconstructed images and may increase the difficulty of diagnosis of myocardial perfusion imaging in women. The null hypothesis tested using the ROC study was that nonuniform AC does not change the lesion detectability in myocardial perfusion SPECT imaging in women. The authors used a filtered backprojection (FBP) reconstruction algorithm and Chang's single iteration method for AC. In conclusion, with the proposed myocardial defect model nuclear medicine physicians demonstrated no significant difference for the detection of the anterior wall defect; however, a greater accuracy for the detection of the inferior wall defect was observed without nonuniform AC than with it. Medical physicists did not demonstrate any statistically significant difference in defect detection accuracy with or without nonuniform AC in the female phantom

Distributed ISAR Subimage Fusion of Nonuniform Rotating Target Based on Matching Fourier Transform.

Science.gov (United States)

Li, Yuanyuan; Fu, Yaowen; Zhang, Wenpeng

2018-06-04

In real applications, the image quality of the conventional monostatic Inverse Synthetic Aperture Radar (ISAR) for the maneuvering target is subject to the strong fluctuation of Radar Cross Section (RCS), as the target aspect varies enormously. Meanwhile, the maneuvering target introduces nonuniform rotation after translation motion compensation which degrades the imaging performance of the conventional Fourier Transform (FT)-based method in the cross-range dimension. In this paper, a method which combines the distributed ISAR technique and the Matching Fourier Transform (MFT) is proposed to overcome these problems. Firstly, according to the characteristics of the distributed ISAR, the multiple channel echoes of the nonuniform rotation target from different observation angles can be acquired. Then, by applying the MFT to the echo of each channel, the defocused problem of nonuniform rotation target which is inevitable by using the FT-based imaging method can be avoided. Finally, after preprocessing, scaling and rotation of all subimages, the noncoherent fusion image containing all the RCS information in all channels can be obtained. The accumulation coefficients of all subimages are calculated adaptively according to the their image qualities. Simulation and experimental data are used to validate the effectiveness of the proposed approach, and fusion image with improved recognizability can be obtained. Therefore, by using the distributed ISAR technique and MFT, subimages of high-maneuvering target from different observation angles can be obtained. Meanwhile, by employing the adaptive subimage fusion method, the RCS fluctuation can be alleviated and more recognizable final image can be obtained.

Security enhanced multi-factor biometric authentication scheme using bio-hash function.

Directory of Open Access Journals (Sweden)

Younsung Choi

Full Text Available With the rapid development of personal information and wireless communication technology, user authentication schemes have been crucial to ensure that wireless communications are secure. As such, various authentication schemes with multi-factor authentication have been proposed to improve the security of electronic communications. Multi-factor authentication involves the use of passwords, smart cards, and various biometrics to provide users with the utmost privacy and data protection. Cao and Ge analyzed various authentication schemes and found that Younghwa An's scheme was susceptible to a replay attack where an adversary masquerades as a legal server and a user masquerading attack where user anonymity is not provided, allowing an adversary to execute a password change process by intercepting the user's ID during login. Cao and Ge improved upon Younghwa An's scheme, but various security problems remained. This study demonstrates that Cao and Ge's scheme is susceptible to a biometric recognition error, slow wrong password detection, off-line password attack, user impersonation attack, ID guessing attack, a DoS attack, and that their scheme cannot provide session key agreement. Then, to address all weaknesses identified in Cao and Ge's scheme, this study proposes a security enhanced multi-factor biometric authentication scheme and provides a security analysis and formal analysis using Burrows-Abadi-Needham logic. Finally, the efficiency analysis reveals that the proposed scheme can protect against several possible types of attacks with only a slightly high computational cost.

Security enhanced multi-factor biometric authentication scheme using bio-hash function.

Science.gov (United States)

Choi, Younsung; Lee, Youngsook; Moon, Jongho; Won, Dongho

2017-01-01

With the rapid development of personal information and wireless communication technology, user authentication schemes have been crucial to ensure that wireless communications are secure. As such, various authentication schemes with multi-factor authentication have been proposed to improve the security of electronic communications. Multi-factor authentication involves the use of passwords, smart cards, and various biometrics to provide users with the utmost privacy and data protection. Cao and Ge analyzed various authentication schemes and found that Younghwa An's scheme was susceptible to a replay attack where an adversary masquerades as a legal server and a user masquerading attack where user anonymity is not provided, allowing an adversary to execute a password change process by intercepting the user's ID during login. Cao and Ge improved upon Younghwa An's scheme, but various security problems remained. This study demonstrates that Cao and Ge's scheme is susceptible to a biometric recognition error, slow wrong password detection, off-line password attack, user impersonation attack, ID guessing attack, a DoS attack, and that their scheme cannot provide session key agreement. Then, to address all weaknesses identified in Cao and Ge's scheme, this study proposes a security enhanced multi-factor biometric authentication scheme and provides a security analysis and formal analysis using Burrows-Abadi-Needham logic. Finally, the efficiency analysis reveals that the proposed scheme can protect against several possible types of attacks with only a slightly high computational cost.

Security enhanced multi-factor biometric authentication scheme using bio-hash function

Science.gov (United States)

Lee, Youngsook; Moon, Jongho

2017-01-01

With the rapid development of personal information and wireless communication technology, user authentication schemes have been crucial to ensure that wireless communications are secure. As such, various authentication schemes with multi-factor authentication have been proposed to improve the security of electronic communications. Multi-factor authentication involves the use of passwords, smart cards, and various biometrics to provide users with the utmost privacy and data protection. Cao and Ge analyzed various authentication schemes and found that Younghwa An’s scheme was susceptible to a replay attack where an adversary masquerades as a legal server and a user masquerading attack where user anonymity is not provided, allowing an adversary to execute a password change process by intercepting the user’s ID during login. Cao and Ge improved upon Younghwa An’s scheme, but various security problems remained. This study demonstrates that Cao and Ge’s scheme is susceptible to a biometric recognition error, slow wrong password detection, off-line password attack, user impersonation attack, ID guessing attack, a DoS attack, and that their scheme cannot provide session key agreement. Then, to address all weaknesses identified in Cao and Ge’s scheme, this study proposes a security enhanced multi-factor biometric authentication scheme and provides a security analysis and formal analysis using Burrows-Abadi-Needham logic. Finally, the efficiency analysis reveals that the proposed scheme can protect against several possible types of attacks with only a slightly high computational cost. PMID:28459867

Locally decodable codes and private information retrieval schemes

CERN Document Server

Yekhanin, Sergey

2010-01-01

Locally decodable codes (LDCs) are codes that simultaneously provide efficient random access retrieval and high noise resilience by allowing reliable reconstruction of an arbitrary bit of a message by looking at only a small number of randomly chosen codeword bits. Local decodability comes with a certain loss in terms of efficiency - specifically, locally decodable codes require longer codeword lengths than their classical counterparts. Private information retrieval (PIR) schemes are cryptographic protocols designed to safeguard the privacy of database users. They allow clients to retrieve rec

Restoration of non-uniform exposure motion blurred image

Science.gov (United States)

Luo, Yuanhong; Xu, Tingfa; Wang, Ningming; Liu, Feng

2014-11-01

Restoring motion-blurred image is the key technologies in the opto-electronic detection system. The imaging sensors such as CCD and infrared imaging sensor, which are mounted on the motion platforms, quickly move together with the platforms of high speed. As a result, the images become blur. The image degradation will cause great trouble for the succeeding jobs such as objects detection, target recognition and tracking. So the motion-blurred images must be restoration before detecting motion targets in the subsequent images. On the demand of the real weapon task, in order to deal with targets in the complex background, this dissertation uses the new theories in the field of image processing and computer vision to research the new technology of motion deblurring and motion detection. The principle content is as follows: 1) When the prior knowledge about degradation function is unknown, the uniform motion blurred images are restored. At first, the blur parameters, including the motion blur extent and direction of PSF(point spread function), are estimated individually in domain of logarithmic frequency. The direction of PSF is calculated by extracting the central light line of the spectrum, and the extent is computed by minimizing the correction between the fourier spectrum of the blurred image and a detecting function. Moreover, in order to remove the strip in the deblurred image, windows technique is employed in the algorithm, which makes the deblurred image clear. 2) According to the principle of infrared image non-uniform exposure, a new restoration model for infrared blurred images is developed. The fitting of infrared image non-uniform exposure curve is performed by experiment data. The blurred images are restored by the fitting curve.

SU-F-E-03: PET/CT Guided Dose Boost to Hypoxic Sub-Volume in Nasopharyngeal Carcinomas Using Self-Optimizing Non-Uniform VMAT

Energy Technology Data Exchange (ETDEWEB)

Qiu, J; Zheng, X; Liu, H; Chen, B; Zhuo, W [FuDan University HuaDong Hospital, Institute of Radiation Medicine Fudan University Shanghai, Shanghai (China)

2016-06-15

Purpose: This study is to evaluate the feasibility of simultaneously integrated boost (SIB) to hypoxic subvolume (HTV) in nasopharyngeal carcinomas under the guidance of 18F-Fluoromisonidazole (FMISO) PET/CT using a novel non-uniform volumetric modulated arc therapy (VMAT)technique. Methods: Eight nasopharyngeal carcinoma patients treated with conventional uniform VMAT were retrospectively analyzed. For each treatment, actual conventional uniform VMAT plan with two or more arcs (2–2.5 arcs, totally rotating angle < 1000o) was designed with dose boost to hopxic subvolume (total dose, 84Gy) in the gross tumor volme (GTV) under the guidance of 18F- FMISO PET/CT. Based on the same dataset, experimental single arc non-uniform VAMT plans were generated with the same dose prescription using customized software tools. Dosimetric parameters, quality assurance and the efficiency of the treatment delivery were compared between the uniform and non-uniform VMAT plans. Results: To develop the non-uniform VMAT technique, a specific optimization model was successfully established. Both techniques generate high-quality plans with pass rate (>98%) with the 3mm, 3% criterion. HTV received dose of 84.1±0.75Gy and 84.1±1.2Gy from uniform and non-uniform VMAT plans, respectively. In terms of target coverage and dose homogeneity, there was no significant statistical difference between actual and experimental plans for each case. However, for critical organs at risk (OAR), including the parotids, oral cavity and larynx, dosimetric difference was significant with better dose sparing form experimental plans. Regarding plan implementation efficiency, the average machine time was 3.5 minutes for the actual VMAT plans and 3.7 minutes for the experimental nonuniform VMAT plans (p>0.050). Conclusion: Compared to conventional VMAT technique, the proposed non-uniform VMAT technique has the potential to produce efficient and safe treatment plans, especially in cases with complicated anatomical

A Stereo Music Preprocessing Scheme for Cochlear Implant Users.

Science.gov (United States)

Buyens, Wim; van Dijk, Bas; Wouters, Jan; Moonen, Marc

2015-10-01

Listening to music is still one of the more challenging aspects of using a cochlear implant (CI) for most users. Simple musical structures, a clear rhythm/beat, and lyrics that are easy to follow are among the top factors contributing to music appreciation for CI users. Modifying the audio mix of complex music potentially improves music enjoyment in CI users. A stereo music preprocessing scheme is described in which vocals, drums, and bass are emphasized based on the representation of the harmonic and the percussive components in the input spectrogram, combined with the spatial allocation of instruments in typical stereo recordings. The scheme is assessed with postlingually deafened CI subjects (N = 7) using pop/rock music excerpts with different complexity levels. The scheme is capable of modifying relative instrument level settings, with the aim of improving music appreciation in CI users, and allows individual preference adjustments. The assessment with CI subjects confirms the preference for more emphasis on vocals, drums, and bass as offered by the preprocessing scheme, especially for songs with higher complexity. The stereo music preprocessing scheme has the potential to improve music enjoyment in CI users by modifying the audio mix in widespread (stereo) music recordings. Since music enjoyment in CI users is generally poor, this scheme can assist the music listening experience of CI users as a training or rehabilitation tool.

Security enhanced anonymous multiserver authenticated key agreement scheme using smart cards and biometrics.

Science.gov (United States)

Choi, Younsung; Nam, Junghyun; Lee, Donghoon; Kim, Jiye; Jung, Jaewook; Won, Dongho

2014-01-01

An anonymous user authentication scheme allows a user, who wants to access a remote application server, to achieve mutual authentication and session key establishment with the server in an anonymous manner. To enhance the security of such authentication schemes, recent researches combined user's biometrics with a password. However, these authentication schemes are designed for single server environment. So when a user wants to access different application servers, the user has to register many times. To solve this problem, Chuang and Chen proposed an anonymous multiserver authenticated key agreement scheme using smart cards together with passwords and biometrics. Chuang and Chen claimed that their scheme not only supports multiple servers but also achieves various security requirements. However, we show that this scheme is vulnerable to a masquerade attack, a smart card attack, a user impersonation attack, and a DoS attack and does not achieve perfect forward secrecy. We also propose a security enhanced anonymous multiserver authenticated key agreement scheme which addresses all the weaknesses identified in Chuang and Chen's scheme.

Security Enhanced Anonymous Multiserver Authenticated Key Agreement Scheme Using Smart Cards and Biometrics

Directory of Open Access Journals (Sweden)

Younsung Choi

2014-01-01

Full Text Available An anonymous user authentication scheme allows a user, who wants to access a remote application server, to achieve mutual authentication and session key establishment with the server in an anonymous manner. To enhance the security of such authentication schemes, recent researches combined user’s biometrics with a password. However, these authentication schemes are designed for single server environment. So when a user wants to access different application servers, the user has to register many times. To solve this problem, Chuang and Chen proposed an anonymous multiserver authenticated key agreement scheme using smart cards together with passwords and biometrics. Chuang and Chen claimed that their scheme not only supports multiple servers but also achieves various security requirements. However, we show that this scheme is vulnerable to a masquerade attack, a smart card attack, a user impersonation attack, and a DoS attack and does not achieve perfect forward secrecy. We also propose a security enhanced anonymous multiserver authenticated key agreement scheme which addresses all the weaknesses identified in Chuang and Chen’s scheme.

The demagnetizing field of a non-uniform rectangular prism

DEFF Research Database (Denmark)

Smith, Anders; Nielsen, Kaspar Kirstein; Christensen, Dennis

2010-01-01

The effect of demagnetization on the magnetic properties of a rectangular ferromagnetic prism under non-uniform conditions is investigated. A numerical model for solving the spatially varying internal magnetic field is developed, validated and applied to relevant cases. The demagnetizing field...... is solved by an analytical calculation and the coupling between applied field, the demagnetization tensor field and spatially varying temperature is solved through iteration. We show that the demagnetizing field is of great importance in many cases and that it is necessary to take into account the non...

How nonuniform contact profiles of T cell receptors modulate thymic selection outcomes

Science.gov (United States)

Chen, Hanrong; Chakraborty, Arup K.; Kardar, Mehran

2018-03-01

T cell receptors (TCRs) bind foreign or self-peptides attached to major histocompatibility complex (MHC) molecules, and the strength of this interaction determines T cell activation. Optimizing the ability of T cells to recognize a diversity of foreign peptides yet be tolerant of self-peptides is crucial for the adaptive immune system to properly function. This is achieved by selection of T cells in the thymus, where immature T cells expressing unique, stochastically generated TCRs interact with a large number of self-peptide-MHC; if a TCR does not bind strongly enough to any self-peptide-MHC, or too strongly with at least one self-peptide-MHC, the T cell dies. Past theoretical work cast thymic selection as an extreme value problem and characterized the statistical enrichment or depletion of amino acids in the postselection TCR repertoire, showing how T cells are selected to be able to specifically recognize peptides derived from diverse pathogens yet have limited self-reactivity. Here, we investigate how the diversity of the postselection TCR repertoire is modified when TCRs make nonuniform contacts with peptide-MHC. Specifically, we were motivated by recent experiments showing that amino acids at certain positions of a TCR sequence have large effects on thymic selection outcomes, and crystal structure data that reveal a nonuniform contact profile between a TCR and its peptide-MHC ligand. Using a representative TCR contact profile as an illustration, we show via simulations that the statistical enrichment or depletion of amino acids now varies by position according to the contact profile, and, importantly, it depends on the implementation of nonuniform contacts during thymic selection. We explain these nontrivial results analytically. Our study has implications for understanding the selection forces that shape the functionality of the postselection TCR repertoire.

A Credit-Based Congestion-Aware Incentive Scheme for DTNs

Directory of Open Access Journals (Sweden)

Qingfeng Jiang

2016-12-01

Full Text Available In Delay-Tolerant Networks (DTNs, nodes may be selfish and reluctant to expend their precious resources on forwarding messages for others. Therefore, an incentive scheme is necessary to motivate selfish nodes to cooperatively forward messages. However, the current incentive schemes mainly focus on encouraging nodes to participate in message forwarding, without considering the node congestion problem. When many messages are forwarded to the nodes with high connection degree, these nodes will become congested and deliberately discard messages, which will seriously degrade the routing performance and reduce the benefits of other nodes. To address this problem, we propose a credit-based congestion-aware incentive scheme (CBCAIS for DTNs. In CBCAIS, a check and punishment mechanism is proposed to prevent forwarding nodes from deliberately discarding message. In addition, a message acceptance selection mechanism is proposed to allow the nodes to decide whether to accept other messages, according to self congestion degree. The experimental results show that CBCAIS can effectively stimulate selfish nodes to cooperatively forward messages, and achieve a higher message delivery ratio with lower overhead ratio, compared with other schemes.

Analysis of effect on microdose of 10B nonuniform distribution in cellular

International Nuclear Information System (INIS)

Xie Qin; Geng Changran; Tang Xiaobin; Chen Da

2012-01-01

Boron neutron capture therapy (BNCT) is one of the effective way to treat malignant melanoma and head-neck cancer. The intercellular nonuniform distributions of 10 B in tumor cell impact the estimates of inactivation dose. The α-Li Version l.0 code was developed based on Monte-Carlo method to calculate the S values of cell induced by α and 7 Li particle which are the products of 10 B (n,a) 7 Li. The calculation included two types of cell size, eight kinds of energy of a particle and three kinds of source distributions. Differences between results of this code and an analytical algorithm of MIRD committee were within 1%. On this basis, a total of 3420 cases were calculated and analyzed with different kinds of nucleus radius, cell radius, and source launch position combination. Finally, cellular S values of 10 B (n,a) 7 Li calculated in this paper can be used to compute the excellent precision dose under 10 B compound nonuniform distribution in intercellular scale. (authors)

Use of extremity insulation during whole body hyperthermia to reduce temperature nonuniformity

International Nuclear Information System (INIS)

Thrall, D.E.; Page, R.L.

1987-01-01

The author previously documented during whole body hyperthermia in dogs using a radiant heating device that temperature at superficial sites, including tibial bone marrow, falls below systemic arterial temperature during the plateau phase of heating. This may be due to direct heat loss to the environment. Sites where temperature is lower than systemic arterial temperature during the plateau phase may become sanctuary sites where tumor deposits are spared because they do not receive the prescribed thermal dose. In an attempt to decrease temperature nonuniformity and increase thermal dose delivered to such superficial sites, extremity insulation has been employed during whole body hyperthermia in dogs. The author measured temperature at cutaneous and subcutaneous sites and within tibial bone marrow in insulated and noninsulated extremities of dogs undergoing whole body hyperthermia in the radiant heating device. The author found that extremity insulation is effective in reducing extremity temperature nonuniformity. Specific results are presented. Extremity insulation may be necessary during whole body hyperthermia to assure that extremity tumor deposits receive a thermal dose similar to that prescribed for the entire body

A Hybrid DGTD-MNA Scheme for Analyzing Complex Electromagnetic Systems

KAUST Repository

Li, Peng

2015-01-07

A hybrid electromagnetics (EM)-circuit simulator for analyzing complex systems consisting of EM devices loaded with nonlinear multi-port lumped circuits is described. The proposed scheme splits the computational domain into two subsystems: EM and circuit subsystems, where field interactions are modeled using Maxwell and Kirchhoff equations, respectively. Maxwell equations are discretized using a discontinuous Galerkin time domain (DGTD) scheme while Kirchhoff equations are discretized using a modified nodal analysis (MNA)-based scheme. The coupling between the EM and circuit subsystems is realized at the lumped ports, where related EM fields and circuit voltages and currents are allowed to “interact’’ via numerical flux. To account for nonlinear lumped circuit elements, the standard Newton-Raphson method is applied at every time step. Additionally, a local time-stepping scheme is developed to improve the efficiency of the hybrid solver. Numerical examples consisting of EM systems loaded with single and multiport linear/nonlinear circuit networks are presented to demonstrate the accuracy, efficiency, and applicability of the proposed solver.

Nonlocal Poisson-Fermi double-layer models: Effects of nonuniform ion sizes on double-layer structure

Science.gov (United States)

Xie, Dexuan; Jiang, Yi

2018-05-01

This paper reports a nonuniform ionic size nonlocal Poisson-Fermi double-layer model (nuNPF) and a uniform ionic size nonlocal Poisson-Fermi double-layer model (uNPF) for an electrolyte mixture of multiple ionic species, variable voltages on electrodes, and variable induced charges on boundary segments. The finite element solvers of nuNPF and uNPF are developed and applied to typical double-layer tests defined on a rectangular box, a hollow sphere, and a hollow rectangle with a charged post. Numerical results show that nuNPF can significantly improve the quality of the ionic concentrations and electric fields generated from uNPF, implying that the effect of nonuniform ion sizes is a key consideration in modeling the double-layer structure.

Pondermotive absorption of a short intense laser pulse in a non-uniform plasma

Energy Technology Data Exchange (ETDEWEB)

Andreev, A A; Platonov, K Yu [Inst. for Laser Physics, SC ` Vavilov State Optical Inst.` 12, Birzhevaya line, St Petersburg (Russian Federation); Tanaka, K A

1998-03-01

An analytical description of the pondermotive absorption mechanism at a short high intense laser pulse interaction with a strong inhomogeneous plasma is presented. The optimal conditions for the maximum of resonance absorption of laser pulse interaction with non-uniform plasma at normal incidence are founded. (author)

Standard compliant channel selection scheme for TV white space networks

CSIR Research Space (South Africa)

Masonta, MT

2014-08-01

Full Text Available CHANNEL DECISION SCHEME The proposed channel selection model is performed based on the flowchart shown in Fig. 1. We assume that the TVWS- BS is authorised and registered with the national GSDB. The model starts when the TVWS-BS queries the GSDB after...-BS will query the GSDB after a predefined period of time until at least more than one channel is available to allow the channel allocation process to start. Fig. 1: Proposed channel selection scheme flowchart A. White Space Channel Attributes Collection Based...

Microscopic image processing system for measuring nonuniform film thickness profiles: Image scanning ellipsometry

International Nuclear Information System (INIS)

Liu, A.H.; Plawsky, J.L.; Wayner, P.C. Jr.

1993-01-01

The long-term objective of this research program is to determine the stability and heat transfer characteristics of evaporating thin films. The current objective is to develop and use a microscopic image-processing system (IPS) which has two parts: an image analyzing interferometer (IAI) and an image scanning ellipsometer (ISE). The primary purpose of this paper is to present the basic concept of ISE, which is a novel technique to measure the two dimensional thickness profile of a non-uniform, thin film, from several nm up to several μm, in a steady state as well as in a transient state. It is a full-field imaging technique which can study every point on the surface simultaneously with high spatial resolution and thickness sensitivity, i.e., it can measure and map the 2-D film thickness profile. The ISE was tested by measuring the thickness profile and the refractive index of a nonuniform solid film

Effects of transverse temperature field nonuniformity on stress in silicon sheet growth

Science.gov (United States)

Mataga, P. A.; Hutchinson, J. W.; Chalmers, B.; Bell, R. O.; Kalejs, J. P.

1987-01-01

Stress and strain rate distributions are calculated using finite element analysis for steady-state growth of thin silicon sheet temperature nonuniformities imposed in the transverse (sheet width) dimension. Significant reductions in residual stress are predicted to occur for the case where the sheet edge is cooled relative to its center provided plastic deformation with high creep rates is present.

The Political Economy of International Emission Trading Scheme Choice: Empirical Evidence

DEFF Research Database (Denmark)

Boom, J.T.; Svendsen, Gert Tinggaard

2000-01-01

The Kyoto Protocol allows emissions trading. It does however not specify how this is to take place and the discussion on the design of an emissions trading scheme is ongoing. In this paper, we give some empirical evidence on the preference of industry and environmental organizations for internati...... for international emissions trading scheme. Since they may have an influence on decision makers, their opinion is important. Our conclusion is that both industry and environmental organizations prefer credit trading, although for widely different reasons....

Key Management Schemes for Peer-to-Peer Multimedia Streaming Overlay Networks

Science.gov (United States)

Naranjo, J. A. M.; López-Ramos, J. A.; Casado, L. G.

Key distribution for multimedia live streaming peer-to-peer overlay networks is a field still in its childhood stage. A scheme designed for networks of this kind must seek security and efficiency while keeping in mind the following restrictions: limited bandwidth, continuous playing, great audience size and clients churn. This paper introduces two novel schemes that allow a trade-off between security and efficiency by allowing to dynamically vary the number of levels used in the key hierarchy. These changes are motivated by great variations in audience size, and initiated by decision of the Key Server. Additionally, a comparative study of both is presented, focusing on security and audience size. Results show that larger key hierarchies can supply bigger audiences, but offer less security against statistical attacks. The opposite happens for shorter key hierarchies.

Exact analysis of Packet Reversed Packet Combining Scheme and Modified Packet Combining Scheme; and a combined scheme

International Nuclear Information System (INIS)

Bhunia, C.T.

2007-07-01

Packet combining scheme is a well defined simple error correction scheme for the detection and correction of errors at the receiver. Although it permits a higher throughput when compared to other basic ARQ protocols, packet combining (PC) scheme fails to correct errors when errors occur in the same bit locations of copies. In a previous work, a scheme known as Packet Reversed Packet Combining (PRPC) Scheme that will correct errors which occur at the same bit location of erroneous copies, was studied however PRPC does not handle a situation where a packet has more than 1 error bit. The Modified Packet Combining (MPC) Scheme that can correct double or higher bit errors was studied elsewhere. Both PRPC and MPC schemes are believed to offer higher throughput in previous studies, however neither adequate investigation nor exact analysis was done to substantiate this claim of higher throughput. In this work, an exact analysis of both PRPC and MPC is carried out and the results reported. A combined protocol (PRPC and MPC) is proposed and the analysis shows that it is capable of offering even higher throughput and better error correction capability at high bit error rate (BER) and larger packet size. (author)

Research of non-uniform multiple hole straighteners for measuring flow rate

International Nuclear Information System (INIS)

Wen Duanzhong; Zhong Dezhen; Cai Zhuti

1989-01-01

Standard throttling flowmeters are widely used in process flow rate measurement. Enough upstream and downstream straight pipe are necessary for it. If not, the error will be increased. Mounting straightener is an effective way for solving this problem. Advantages of non-uniform multiple hole straighteners studied by authors are good results for straighting, simple in Structure, convenient for mounting and low cost. So it can be popularized in many applications

Interpretation of UV radiometric measurements of spectrally non-uniform sources

International Nuclear Information System (INIS)

Murphy, P.J.; Gardner, D.G.

1988-01-01

Narrow bandpass UV radiometers are used in a variety of high-temperature measurement applications. Significant systematic errors, in the form of an apparent wavelength shift in the system response curve, may be introduced when interpreting data obtained from spectrally nonuniform sources. Theoretical calculations, using transmission curves from commercially available narrow bandpass filters, show that the apparent shift in the system spectral response is a function of temperature for a blackbody source. A brief comparison between the theoretical analysis and experimentaal data is presented

Experimental study on the CHF in uniformly and non-uniformly heated vertical annuli

Energy Technology Data Exchange (ETDEWEB)

Chun, Se Young; Moon, Sang Ki; Chung, Heung June; Park, Jong Kuk; Kim, Bok Deuk; Youn, Young Jung; Chung, Moon Ki

2001-09-01

Up to now, KAERI has performed critical heat flux experiments in water under zero-flow and low-flow conditions using a RCS CHF loop facility with uniformly and non-uniformly heated vertical annulus. Since the existing CHF experiments were mainly performed under low-pressure conditions, we performed the CHF experiment to investigate the pressure effect on the CHF under zero-flow and low-flow conditions for a wide range of system pressures. Also, two vertical annuli with the same geometry have been used to investigate the axial heat flux distributions on the CHF. This report summarizes the experimental results and provides the CHF data that can be used for the development for CHF correlation and a thermal hydraulic analysis code. The CHF data have been collected for system pressures ranging from 0.57 to 15.15 MPa, mass flux 0 and from 200 to 650 kg/m2s, inlet subcooling from 75 to 360 kJ/kg and exit quality from 0.07 to 0.57. At low-flow conditions, the total number of data are 242 and 290 with uniformly heated- and non-uniformly heated test sections, respectively. 41 and 94 CHF data are generated with uniformly heated- and non-uniformly heated test sections, respectively, in zero-flow CHF experiments that are performed by blocking test section bottoms. The CHF experiment result shows that the effects of system pressure, mass flux and inlet subcooling are consistent with conventional understandings and similar to those for round tubes. The behavior of the CHF is relatively complex at low pressures. Also, the effects of axial heat flux profile are large at low-pressure conditions.

Experimental study on the CHF in uniformly and non-uniformly heated vertical annuli

International Nuclear Information System (INIS)

Chun, Se Young; Moon, Sang Ki; Chung, Heung June; Park, Jong Kuk; Kim, Bok Deuk; Youn, Young Jung; Chung, Moon Ki

2001-09-01

Up to now, KAERI has performed critical heat flux experiments in water under zero-flow and low-flow conditions using a RCS CHF loop facility with uniformly and non-uniformly heated vertical annulus. Since the existing CHF experiments were mainly performed under low-pressure conditions, we performed the CHF experiment to investigate the pressure effect on the CHF under zero-flow and low-flow conditions for a wide range of system pressures. Also, two vertical annuli with the same geometry have been used to investigate the axial heat flux distributions on the CHF. This report summarizes the experimental results and provides the CHF data that can be used for the development for CHF correlation and a thermal hydraulic analysis code. The CHF data have been collected for system pressures ranging from 0.57 to 15.15 MPa, mass flux 0 and from 200 to 650 kg/m2s, inlet subcooling from 75 to 360 kJ/kg and exit quality from 0.07 to 0.57. At low-flow conditions, the total number of data are 242 and 290 with uniformly heated- and non-uniformly heated test sections, respectively. 41 and 94 CHF data are generated with uniformly heated- and non-uniformly heated test sections, respectively, in zero-flow CHF experiments that are performed by blocking test section bottoms. The CHF experiment result shows that the effects of system pressure, mass flux and inlet subcooling are consistent with conventional understandings and similar to those for round tubes. The behavior of the CHF is relatively complex at low pressures. Also, the effects of axial heat flux profile are large at low-pressure conditions

Impact of roof height non-uniformity on pollutant transport between a street canyon and intersections

International Nuclear Information System (INIS)

Nosek, Štěpán; Kukačka, Libor; Jurčáková, Klára; Kellnerová, Radka; Jaňour, Zbyněk

2017-01-01

This paper presents an extension of our previous wind-tunnel study (Nosek et al., 2016) in which we highlighted the need for investigation of the removal mechanisms of traffic pollution from all openings of a 3D street canyon. The extension represents the pollution flux (turbulent and advective) measurements at the lateral openings of three different 3D street canyons for the winds perpendicular and oblique to the along-canyon axis. The pollution was simulated by emitting a passive gas (ethane) from a homogeneous ground-level line source positioned along the centreline of the investigated street canyons. The street canyons were formed by courtyard-type buildings of two different regular urban-array models. The first model has a uniform building roof height, while the second model has a non-uniform roof height along each building's wall. The mean flow and concentration fields at the canyons' lateral openings confirm the findings of other studies that the buildings' roof-height variability at the intersections plays an important role in the dispersion of the traffic pollutants within the canyons. For the perpendicular wind, the non-uniform roof-height canyon appreciably removes or entrains the pollutant through its lateral openings, contrary to the uniform canyon, where the pollutant was removed primarily through the top. The analysis of the turbulent mass transport revealed that the coherent flow structures of the lateral momentum transport correlate with the ventilation processes at the lateral openings of all studied canyons. These flow structures coincide at the same areas and hence simultaneously transport the pollutant in opposite directions. - Highlights: • The pollutant transport strongly depends on the roof-height arrangement. • The non-uniform canyons also remove the pollutants through their lateral openings. • The higher the upstream wall, the more pollutant is removed through the top. • The lateral coherent structures correlate

The IFIEC method for the allocation of CO2 allowances in the EU Emissions Trading Scheme. A review applied to the electricity sector

International Nuclear Information System (INIS)

Bart Wesselink; Sebastian Klaus Alyssa; Gilbert Kornelis Blok

2008-03-01

Recently the European Commission has published a proposal to improve the function of the EU-ETS by amending the Directive which establishes the EU-ETS. The main changes proposed are the establishment of one EU-wide cap and the use of auctioning for a much greater share of allowances than is currently the case, replacing most of the allocation free of charge. Auctioning of allowances will eliminate the so-called windfall profits that occur under the current allocation free of charge that is based on historic production and emission levels; a grandfathering approach. IFIEC EUROPE, the international federation of industrial energy consumers, asked Ecofys to review the method that IFIEC has developed in recent years to allocate CO2 allowances in the EU emissions trading scheme (EU-ETS). According to IFIEC, their allocation method guarantees the same environmental outcome as other methods, without causing windfall profits and with lower risks of competitiveness loss for so-called exposed industrial users of electricity. It was decided to focus this study on the European electricity sector. This was done for several reasons: CO2 emissions from electricity generation cover a large part of the overall emission under EU-ETS, the electricity sector has a single well defined output (electricity) that can be used to illustrate the potential impact of the IFIEC benchmark based allocation approach, and electricity is a substantial cost factor for IFIEC members. This evaluation covers many aspects of IFIEC's method and compares these with two other allocation methods: auctioning and historic grandfathering. Within the IFIEC method two example approaches are evaluated: a single benchmark for electricity production and fuel-specific benchmarks for coal and gas fired electricity production. In the evaluation, we cover the following aspects: What is the IFIEC method; how does it differ from other allocation methods in character (chapter 2); What is the impact of different allocation

Effective Quality-of-Service Renegotiating Schemes for Streaming Video

Directory of Open Access Journals (Sweden)

Song Hwangjun

2004-01-01

Full Text Available This paper presents effective quality-of-service renegotiating schemes for streaming video. The conventional network supporting quality of service generally allows a negotiation at a call setup. However, it is not efficient for the video application since the compressed video traffic is statistically nonstationary. Thus, we consider the network supporting quality-of-service renegotiations during the data transmission and study effective quality-of-service renegotiating schemes for streaming video. The token bucket model, whose parameters are token filling rate and token bucket size, is adopted for the video traffic model. The renegotiating time instants and the parameters are determined by analyzing the statistical information of compressed video traffic. In this paper, two renegotiating approaches, that is, fixed renegotiating interval case and variable renegotiating interval case, are examined. Finally, the experimental results are provided to show the performance of the proposed schemes.

Efficient and Provable Secure Pairing-Free Security-Mediated Identity-Based Identification Schemes

Directory of Open Access Journals (Sweden)

Ji-Jian Chin

2014-01-01

Full Text Available Security-mediated cryptography was first introduced by Boneh et al. in 2001. The main motivation behind security-mediated cryptography was the capability to allow instant revocation of a user’s secret key by necessitating the cooperation of a security mediator in any given transaction. Subsequently in 2003, Boneh et al. showed how to convert a RSA-based security-mediated encryption scheme from a traditional public key setting to an identity-based one, where certificates would no longer be required. Following these two pioneering papers, other cryptographic primitives that utilize a security-mediated approach began to surface. However, the security-mediated identity-based identification scheme (SM-IBI was not introduced until Chin et al. in 2013 with a scheme built on bilinear pairings. In this paper, we improve on the efficiency results for SM-IBI schemes by proposing two schemes that are pairing-free and are based on well-studied complexity assumptions: the RSA and discrete logarithm assumptions.

Efficient and provable secure pairing-free security-mediated identity-based identification schemes.

Science.gov (United States)

Chin, Ji-Jian; Tan, Syh-Yuan; Heng, Swee-Huay; Phan, Raphael C-W

2014-01-01

Security-mediated cryptography was first introduced by Boneh et al. in 2001. The main motivation behind security-mediated cryptography was the capability to allow instant revocation of a user's secret key by necessitating the cooperation of a security mediator in any given transaction. Subsequently in 2003, Boneh et al. showed how to convert a RSA-based security-mediated encryption scheme from a traditional public key setting to an identity-based one, where certificates would no longer be required. Following these two pioneering papers, other cryptographic primitives that utilize a security-mediated approach began to surface. However, the security-mediated identity-based identification scheme (SM-IBI) was not introduced until Chin et al. in 2013 with a scheme built on bilinear pairings. In this paper, we improve on the efficiency results for SM-IBI schemes by proposing two schemes that are pairing-free and are based on well-studied complexity assumptions: the RSA and discrete logarithm assumptions.

An Efficient Code-Based Threshold Ring Signature Scheme with a Leader-Participant Model

Directory of Open Access Journals (Sweden)

Guomin Zhou

2017-01-01

Full Text Available Digital signature schemes with additional properties have broad applications, such as in protecting the identity of signers allowing a signer to anonymously sign a message in a group of signers (also known as a ring. While these number-theoretic problems are still secure at the time of this research, the situation could change with advances in quantum computing. There is a pressing need to design PKC schemes that are secure against quantum attacks. In this paper, we propose a novel code-based threshold ring signature scheme with a leader-participant model. A leader is appointed, who chooses some shared parameters for other signers to participate in the signing process. This leader-participant model enhances the performance because every participant including the leader could execute the decoding algorithm (as a part of signing process upon receiving the shared parameters from the leader. The time complexity of our scheme is close to Courtois et al.’s (2001 scheme. The latter is often used as a basis to construct other types of code-based signature schemes. Moreover, as a threshold ring signature scheme, our scheme is as efficient as the normal code-based ring signature.

An improved anonymous authentication scheme for roaming in ubiquitous networks.

Science.gov (United States)

Lee, Hakjun; Lee, Donghoon; Moon, Jongho; Jung, Jaewook; Kang, Dongwoo; Kim, Hyoungshick; Won, Dongho

2018-01-01

With the evolution of communication technology and the exponential increase of mobile devices, the ubiquitous networking allows people to use our data and computing resources anytime and everywhere. However, numerous security concerns and complicated requirements arise as these ubiquitous networks are deployed throughout people's lives. To meet the challenge, the user authentication schemes in ubiquitous networks should ensure the essential security properties for the preservation of the privacy with low computational cost. In 2017, Chaudhry et al. proposed a password-based authentication scheme for the roaming in ubiquitous networks to enhance the security. Unfortunately, we found that their scheme remains insecure in its protection of the user privacy. In this paper, we prove that Chaudhry et al.'s scheme is vulnerable to the stolen-mobile device and user impersonation attacks, and its drawbacks comprise the absence of the incorrect login-input detection, the incorrectness of the password change phase, and the absence of the revocation provision. Moreover, we suggest a possible way to fix the security flaw in Chaudhry et al's scheme by using the biometric-based authentication for which the bio-hash is applied in the implementation of a three-factor authentication. We prove the security of the proposed scheme with the random oracle model and formally verify its security properties using a tool named ProVerif, and analyze it in terms of the computational and communication cost. The analysis result shows that the proposed scheme is suitable for resource-constrained ubiquitous environments.

An improved anonymous authentication scheme for roaming in ubiquitous networks.

Directory of Open Access Journals (Sweden)

Hakjun Lee

Full Text Available With the evolution of communication technology and the exponential increase of mobile devices, the ubiquitous networking allows people to use our data and computing resources anytime and everywhere. However, numerous security concerns and complicated requirements arise as these ubiquitous networks are deployed throughout people's lives. To meet the challenge, the user authentication schemes in ubiquitous networks should ensure the essential security properties for the preservation of the privacy with low computational cost. In 2017, Chaudhry et al. proposed a password-based authentication scheme for the roaming in ubiquitous networks to enhance the security. Unfortunately, we found that their scheme remains insecure in its protection of the user privacy. In this paper, we prove that Chaudhry et al.'s scheme is vulnerable to the stolen-mobile device and user impersonation attacks, and its drawbacks comprise the absence of the incorrect login-input detection, the incorrectness of the password change phase, and the absence of the revocation provision. Moreover, we suggest a possible way to fix the security flaw in Chaudhry et al's scheme by using the biometric-based authentication for which the bio-hash is applied in the implementation of a three-factor authentication. We prove the security of the proposed scheme with the random oracle model and formally verify its security properties using a tool named ProVerif, and analyze it in terms of the computational and communication cost. The analysis result shows that the proposed scheme is suitable for resource-constrained ubiquitous environments.

Vacuum polarisation in some static nonuniform magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Calucci, G. [Trieste Univ. (Italy). Dip. di Fisica Teorica]|[INFN, Trieste (Italy)

1995-11-01

Vacuum polarisation in QED in presence of some configurations of external magnetic fields is investigated. The configuration considered correspond to fields is investigated. The configuration considered correspond to fields lying in a plane and without sources. The motion of a Dirac electron in this field configuration is studied and arguments are found to conclude that the lowest level gives the most important contribution. The result is that the main effect is not very different from the uniform case, the possibilities of calculating the corrections due to the uniformity is explicitly shown. A typical effect of nonuniformity of the field shows out in the refractivity of the field shows out in the refractivity of the vacuum.

Vacuum polarisation in some static nonuniform magnetic fields

International Nuclear Information System (INIS)

Calucci, G.

1995-11-01

Vacuum polarisation in QED in presence of some configurations of external magnetic fields is investigated. The configuration considered correspond to fields is investigated. The configuration considered correspond to fields lying in a plane and without sources. The motion of a Dirac electron in this field configuration is studied and arguments are found to conclude that the lowest level gives the most important contribution. The result is that the main effect is not very different from the uniform case, the possibilities of calculating the corrections due to the uniformity is explicitly shown. A typical effect of nonuniformity of the field shows out in the refractivity of the field shows out in the refractivity of the vacuum

One-step fabrication of nanostructure-covered microstructures using selective aluminum anodization based on non-uniform electric field

Science.gov (United States)

Park, Yong Min; Kim, Byeong Hee; Seo, Young Ho

2016-06-01

This paper presents a selective aluminum anodization technique for the fabrication of microstructures covered by nanoscale dome structures. It is possible to fabricate bulging microstructures, utilizing the different growth rates of anodic aluminum oxide in non-uniform electric fields, because the growth rate of anodic aluminum oxide depends on the intensity of electric field, or current density. After anodizing under a non-uniform electric field, bulging microstructures covered by nanostructures were fabricated by removing the residual aluminum layer. The non-uniform electric field induced by insulative micropatterns was estimated by computational simulations and verified experimentally. Utilizing computational simulations, the intensity profile of the electric field was calculated according to the ratio of height and width of the insulative micropatterns. To compare computational simulation results and experimental results, insulative micropatterns were fabricated using SU-8 photoresist. The results verified that the shape of the bottom topology of anodic alumina was strongly dependent on the intensity profile of the applied electric field, or current density. The one-step fabrication of nanostructure-covered microstructures can be applied to various fields, such as nano-biochip and nano-optics, owing to its simplicity and cost effectiveness.

GRAP, Gamma-Ray Level-Scheme Assignment

International Nuclear Information System (INIS)

Franklyn, C.B.

2002-01-01

1 - Description of program or function: An interactive program for allocating gamma-rays to an energy level scheme. Procedure allows for searching for new candidate levels of the form: 1) L1 + G(A) + G(B) = L2; 2) G(A) + G(B) = G(C); 3) G(A) + G(B) = C (C is a user defined number); 4) L1 + G(A) + G(B) + G(C) = L2. Procedure indicates intensity balance of feed and decay of each energy level. Provides for optimization of a level energy (and associated error). Overall procedure allows for pre-defining of certain gamma-rays as belonging to particular regions of the level scheme, for example, high energy transition levels, or due to beta- decay. 2 - Method of solution: Search for cases in which the energy difference between two energy levels is equal to a gamma-ray energy within user-defined limits. 3 - Restrictions on the complexity of the problem: Maximum number of gamma-rays: 999; Maximum gamma ray energy: 32000 units; Minimum gamma ray energy: 10 units; Maximum gamma-ray intensity: 32000 units; Minimum gamma-ray intensity: 0.001 units; Maximum number of levels: 255; Maximum level energy: 32000 units; Minimum level energy: 10 units; Maximum error on energy, intensity: 32 units; Minimum error on energy, intensity: 0.001 units; Maximum number of combinations: 6400 (ca); Maximum number of gamma-ray types : 127

Compatible discrete operator schemes on polyhedral meshes for elliptic and Stokes equations

International Nuclear Information System (INIS)

Bonelle, Jerome

2014-01-01

This thesis presents a new class of spatial discretization schemes on polyhedral meshes, called Compatible Discrete Operator (CDO) schemes and their application to elliptic and Stokes equations In CDO schemes, preserving the structural properties of the continuous equations is the leading principle to design the discrete operators. De Rham maps define the degrees of freedom according to the physical nature of fields to discretize. CDO schemes operate a clear separation between topological relations (balance equations) and constitutive relations (closure laws). Topological relations are related to discrete differential operators, and constitutive relations to discrete Hodge operators. A feature of CDO schemes is the explicit use of a second mesh, called dual mesh, to build the discrete Hodge operator. Two families of CDO schemes are considered: vertex-based schemes where the potential is located at (primal) mesh vertices, and cell-based schemes where the potential is located at dual mesh vertices (dual vertices being in one-to-one correspondence with primal cells). The CDO schemes related to these two families are presented and their convergence is analyzed. A first analysis hinges on an algebraic definition of the discrete Hodge operator and allows one to identify three key properties: symmetry, stability, and P0-consistency. A second analysis hinges on a definition of the discrete Hodge operator using reconstruction operators, and the requirements on these reconstruction operators are identified. In addition, CDO schemes provide a unified vision on a broad class of schemes proposed in the literature (finite element, finite element, mimetic schemes... ). Finally, the reliability and the efficiency of CDO schemes are assessed on various test cases and several polyhedral meshes. (author)

A versatile lattice for a tau-charm factory that includes a monochromatization scheme

International Nuclear Information System (INIS)

Faus-Golfe, A.; Le Duff, J.

1992-02-01

A double ring system with multibunch scheme and high luminosity is discussed. An attempt for beam monochromatization at the crossing point was made by increasing the vertical bending angle, and it succeeded in providing a proper matching. The next step consisted of demonstrating that the new ring geometry that permits a monochromatization scheme could be returned and rematched to operate without monochromatization, allowing only relocation of quadrupoles and readjustment of their gradient in the sloping region. The results of this work are reported after a brief recall of the monochromatization scheme requirements. (K.A.) 10 refs., 13 figs., 2 tabs

On the Super-Turing Computational Power of Non-Uniform Families of Neuromata

Czech Academy of Sciences Publication Activity Database

Wiedermann, Jiří

2002-01-01

Roč. 12, č. 5 (2002), s. 509-516 ISSN 1210-0552. [SOFSEM 2002 Workshop on Soft Computing. Milovy, 28.11.2002-29.11.2002] R&D Projects: GA ČR GA201/00/1489 Institutional research plan: AV0Z1030915 Keywords : neuromata * Turing machines with advice * non-uniform computational complexity * super-Turing computational power Subject RIV: BA - General Mathematics

Viscoelastic Fluid over a Stretching Sheet with Electromagnetic Effects and Nonuniform Heat Source/Sink

Directory of Open Access Journals (Sweden)

Kai-Long Hsiao

2010-01-01

Full Text Available A magnetic hydrodynamic (MHD of an incompressible viscoelastic fluid over a stretching sheet with electric and magnetic dissipation and nonuniform heat source/sink has been studied. The buoyant effect and the electric number E1 couple with magnetic parameter M to represent the dominance of the electric and magnetic effects, and adding the specific item of nonuniform heat source/sink is presented in governing equations which are the main contribution of this study. The similarity transformation, the finite-difference method, Newton method, and Gauss elimination method have been used to analyze the present problem. The numerical solutions of the flow velocity distributions, temperature profiles, and the important wall unknown values of f''(0 and θ'(0 have been carried out. The parameter Pr, E1, or Ec can increase the heat transfer effects, but the parameter M or A* may decrease the heat transfer effects.

Haldane model under nonuniform strain

Science.gov (United States)

Ho, Yen-Hung; Castro, Eduardo V.; Cazalilla, Miguel A.

2017-10-01

We study the Haldane model under strain using a tight-binding approach, and compare the obtained results with the continuum-limit approximation. As in graphene, nonuniform strain leads to a time-reversal preserving pseudomagnetic field that induces (pseudo-)Landau levels. Unlike a real magnetic field, strain lifts the degeneracy of the zeroth pseudo-Landau levels at different valleys. Moreover, for the zigzag edge under uniaxial strain, strain removes the degeneracy within the pseudo-Landau levels by inducing a tilt in their energy dispersion. The latter arises from next-to-leading order corrections to the continuum-limit Hamiltonian, which are absent for a real magnetic field. We show that, for the lowest pseudo-Landau levels in the Haldane model, the dominant contribution to the tilt is different from graphene. In addition, although strain does not strongly modify the dispersion of the edge states, their interplay with the pseudo-Landau levels is different for the armchair and zigzag ribbons. Finally, we study the effect of strain in the band structure of the Haldane model at the critical point of the topological transition, thus shedding light on the interplay between nontrivial topology and strain in quantum anomalous Hall systems.

Tamper-proof secret image-sharing scheme for identifying cheated secret keys and shared images

Science.gov (United States)

Chen, Chien-Chang; Liu, Chong-An

2013-01-01

A (t,n) secret image-sharing scheme shares a secret image to n participants, and the t users recover the image. During the recovery procedure of a conventional secret image-sharing scheme, cheaters may use counterfeit secret keys or modified shared images to cheat other users' secret keys and shared images. A cheated secret key or shared image leads to an incorrect secret image. Unfortunately, the cheater cannot be identified. We present an exponent and modulus-based scheme to provide a tamper-proof secret image-sharing scheme for identifying cheaters on secret keys or shared images. The proposed scheme allows users to securely select their secret key. This assignment can be performed over networks. Modulus results of each shared image is calculated to recognize cheaters of a shared image. Experimental results indicate that the proposed scheme is excellent at identifying cheated secret keys and shared images.

Advanced lattice Boltzmann scheme for high-Reynolds-number magneto-hydrodynamic flows

Science.gov (United States)

De Rosis, Alessandro; Lévêque, Emmanuel; Chahine, Robert

2018-06-01

Is the lattice Boltzmann method suitable to investigate numerically high-Reynolds-number magneto-hydrodynamic (MHD) flows? It is shown that a standard approach based on the Bhatnagar-Gross-Krook (BGK) collision operator rapidly yields unstable simulations as the Reynolds number increases. In order to circumvent this limitation, it is here suggested to address the collision procedure in the space of central moments for the fluid dynamics. Therefore, an hybrid lattice Boltzmann scheme is introduced, which couples a central-moment scheme for the velocity with a BGK scheme for the space-and-time evolution of the magnetic field. This method outperforms the standard approach in terms of stability, allowing us to simulate high-Reynolds-number MHD flows with non-unitary Prandtl number while maintaining accuracy and physical consistency.

Radiation flaw detector for testing non-uniform surface bodies of revolution

International Nuclear Information System (INIS)

Valevich, M.I.

1984-01-01

Radiation flaw detector for testing bodies of revolution with non-uniform surface, welded joints, etc., based on spatial filtration and differentiation of ionizing radiation flux has been described. The calculation of the most important unit of flaw detector - integrators - is made. Experimental studies of the sensitivity have shown, that the radiation flaw detector can be used for rapid testing of products with the sensitivity comparable with the sensitivity of radiographic testing of steel

Novel powering schemes for pixel and tracking detectors

CERN Document Server

Feld, Lutz Werner

2013-01-01

Future pixel and tracking systems like the ones foreseen in the upgrade programs of the LHC experiments are very demanding on the power supply systems. An increased amount of power has to be supplied to the front-end electronics at a reduced voltage, through existing cable plants. Novel powering schemes are needed to avoid excessive cable losses. The two schemes under consideration, serial powering and DC-DC conversion, are reviewed. Particular emphasis is put on system integration aspects. As an example, the new CMS pixel system, which will be powered via DC-DC conversion, is presented in more detail. This allows to discuss challenges and solutions for a concrete application while the conclusions should be relevant for other applications as well.

Direct-driven target implosion in heavy ion fusion

International Nuclear Information System (INIS)

Noguchi, K.; Suzuki, T.; Kurosaki, T.; Barada, D.; Kawata, S.; Ma, Y. Y.; Ogoyski, A. I.

2016-01-01

In inertial confinement fusion, the driver beam illumination non-uniformity leads a degradation of fusion energy output. A fuel target alignment error would happen in a fusion reactor; the target alignment error induces heavy ion beam illumination non-uniformity on a target. On the other hand, heavy ion beam accelerator provides a capability to oscillate a beam axis with a high frequency. The wobbling beams may provide a new method to reduce or smooth the beam illumination non-uniformity. First we study the effect of driver irradiation non-uniformity induced by the target alignment error (dz) on the target implosion. We found that dz should be less than about 130 μm for a sufficient fusion energy output. We also optimize the wobbling scheme. The spiral wobbling heavy ion beams would provide a promissing scheme to the uniform beam illumination. (paper)

Finite Boltzmann schemes

NARCIS (Netherlands)

Sman, van der R.G.M.

2006-01-01

In the special case of relaxation parameter = 1 lattice Boltzmann schemes for (convection) diffusion and fluid flow are equivalent to finite difference/volume (FD) schemes, and are thus coined finite Boltzmann (FB) schemes. We show that the equivalence is inherent to the homology of the

Improvements and validation of the linear surface characteristics scheme

International Nuclear Information System (INIS)

Santandrea, S.; Jaboulay, J.C.; Bellier, P.; Fevotte, F.; Golfier, H.

2009-01-01

In this paper we present the last improvements of the recently proposed linear surface (LS) characteristics scheme for unstructured meshes. First we introduce a new numerical tracking technique, specifically adapted to the LS method, which tailors transverse integration weights to take into account the geometrical discontinuities that appear along the pipe affected to every trajectory in classical characteristics schemes. Another development allows using the volumetric flux variation of the LS method to re-compute step-wise constant fluxes to be used in other parts of a computational scheme. This permits to take greater advantage of the higher precision of the LS method without necessarily conceiving specialized theories for all the modular functionalities of a spectral code such as APOLLO2. Moreover we present a multi-level domain decomposition method for solving the synthetic acceleration operator that is used to accelerate the free iterations for the LS method. We discuss all these new developments by illustrating some benchmarks results obtained with the LS method. This is done by detailed comparisons with Monte-Carlo calculations. In particular we show that the new method can be used not only as a reference tool, but also inside a suitable industrial calculation scheme

Effect of non-uniform mean flow field on acoustic propagation problems in computational aeroacoustics

DEFF Research Database (Denmark)

Si, Haiqing; Shen, Wen Zhong; Zhu, Wei Jun

2013-01-01

Acoustic propagation in the presence of a non-uniform mean flow is studied numerically by using two different acoustic propagating models, which solve linearized Euler equations (LEE) and acoustic perturbation equations (APE). As noise induced by turbulent flows often propagates from near field t...

Direct numerical simulation of turbulent pipe flow with nonuniform surface heat flux

International Nuclear Information System (INIS)

Satake, Shin-ichi; Kunugi, Tomoaki

1998-01-01

Turbulent transport computations of a scalar quantity for fully-developed turbulent pipe flow were carried out by means of a direct numerical simulation (DNS) procedure. In this paper, three wall-heating boundary conditions were considered as follows: Case-1) a uniform heat-flux condition along the wall, Case-2) a nonuniform wall-heating condition, that is, a cosine heat-flux distribution along the wall and Case-3) a nonuniform wall-heating condition with a constant temperature over a half of the pipe wall. The number of computational grids used in this paper is 256 x 128 x 128. Prandtl number of the working fluid is 0.71. The Nusselt number in case of Case-1 is in good agreement with the empirical correlation. In case of Case-3, the distributions of the turbulent quantity and the Nusselt number seem to be reasonable. However, as for Case-2, the distributions of the turbulent quantity and the Nusselt number seem to be unrealistic. Two numerical treatments of thermal boundary condition on the wall were applied and their results were discussed from the viewpoint of the turbulent transport feature. (author)

Optical property of few-mode fiber with non-uniform refractive index for cylindrical vector beam generation

Science.gov (United States)

Li, Hongye; Wan, Hongdan; Zhang, Zuxing; Sun, Bing; Zhang, Lin

2016-10-01

This paper investigates optical properties of few-mode fiber with non-uniform refractive index, namely: the few mode fiber with U-shape refractive index and the two-mode and four-mode few-mode fiber with bent radius. Finite element method is used to analyze the mode distributions based on their non-uniform refractive index. Effective mode control can be achieved through these few mode fibers to achieve vector beam generation. Finally, reflection spectra of a few-mode fiber Bragg grating are calculated theoretically and then measured under different bending conditions. Experimental results are in good accordance with the theoretical ones. These few mode fibers show potential applications in generation of cylindrical vector beam both for optical lasing and sensing systems.

Non-Uniform Heat Transfer in Thermal Regenerators

DEFF Research Database (Denmark)

Jensen, Jesper Buch

, a numerical model, which simulates a single-blow operation in a parallel-plate regenerator, was developed and used to model the heat transfer under various conditions. In addition to the modeling of the heat transfer, a series of experiments on passive regenerators with non-uniform, but precisely controlled....... Additionally, the experiments gave real comparative results, whereas the model to a certain degree more served to provide insight to the heat transfer processes taking place inside the regenera- tors, something that would be - if not impossible - then highly impractical to do experimentally. It has been found......This thesis presents investigations on the heat transfer in complex heat ex- changers in general and in regenerative heat exchangers (regenerators) in par- ticular. The motivation for this work is a result of inconsistencies obeserved in the results from a series of experiments on active magnetic...

Nonuniform radiation damage in permanent magnet quadrupoles.

Science.gov (United States)

Danly, C R; Merrill, F E; Barlow, D; Mariam, F G

2014-08-01

We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL's pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

Nonuniform radiation damage in permanent magnet quadrupoles

International Nuclear Information System (INIS)

Danly, C. R.; Merrill, F. E.; Barlow, D.; Mariam, F. G.

2014-01-01

We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components

Nonuniform radiation damage in permanent magnet quadrupoles

Energy Technology Data Exchange (ETDEWEB)

Danly, C. R.; Merrill, F. E.; Barlow, D.; Mariam, F. G. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)

2014-08-15

We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

Numerical study of a hybrid jet impingement/micro-channel cooling scheme

International Nuclear Information System (INIS)

Barrau, Jérôme; Omri, Mohammed; Chemisana, Daniel; Rosell, Joan; Ibañez, Manel; Tadrist, Lounes

2012-01-01

A new hybrid jet impingement/micro-channel cooling scheme is studied numerically for use in high-heat-flux thermal management of electronic and power devices. The device is developed with the objective of improving the temperature uniformity of the cooled object. A numerical model based on the k–ω SST turbulent model is developed and validated experimentally. This model is used to carry out a parametrical characterization of the heat sink. The study shows that variations in key parameters of jet impingement and micro-channel technologies allow for the cooling scheme to obtain a wide range of temperature profiles for the cooled object. - Highlights: ► A new hybrid cooling scheme is numerically studied. ► The cooling scheme combines the benefits of jet impingement and micro-channel flows. ► The numerical model is validated by comparison with experimental results. ► The temperature distribution can be adapted to the needs of the cooled system.

Influence of the Emissions Trading Scheme on generation scheduling

International Nuclear Information System (INIS)

Kockar, Ivana; McDonald, James R.; Conejo, Antonio J.

2009-01-01

The paper investigates the effects of emissions constraints and Emissions Trading Scheme (ETS) on the generation scheduling outcome. ETS is a cap-and-trade market mechanism that has been introduced in European Union in order to facilitate CO 2 emissions management. This scheme gives generators certain amount of CO 2 allowances which they can use to cover emissions produced during energy generation. In a current setting, most of the allowances are given for free. However, under ETS generators also have an opportunity to buy and sell CO 2 allowances on the market. Since generation power outputs are bounded by the amount of CO 2 emissions that they are allowed to produce over time, it is becoming increasingly important for generating units to manage their allocations in the most profitable way and decide when and how much of permissions to spent to produce electricity. The method proposed here allows for modeling of this new limitation by including costs of buying and selling of CO 2 allowance in the generation scheduling procedure. It also introduces additional emissions constraints in the problem formulation. Although CO 2 permissions and energy are traded in separate markets, the proposed formulation permits analysis on how emission caps and emission market prices can influence market outcome. The method is illustrated on a 5-unit system. Given examples compare (i) a base-case when all generators have made a decision to use portions of their total free allocations that do not cause any shortfall during the investigated time period; (ii) two cases when the least expensive generators' decisions on the amount of free allowances they are willing to use during the considered period are insufficient. In all cases generators also submit prices at which they expect to be able to ''top-up'' or sell allowances on the market, however, only in the second and third case the ''buying'' option becomes active and affects generation scheduling and total costs. In addition, the

Firm performance and employment in the EU emissions trading scheme: An empirical assessment for Germany

International Nuclear Information System (INIS)

Anger, Niels; Oberndorfer, Ulrich

2008-01-01

This paper empirically investigates the role of the EU Emissions Trading Scheme (EU ETS) for firm performance and employment in Germany. We provide an overview of relative allowance allocation within the EU ETS as well as an econometric analysis for a large sample of German firms covered by the scheme in order to assess the impacts of EU emissions regulation on both firm revenues and employment. The dataset indicates that the EU ETS was in an overall long position in 2005, although allowance allocation was very heterogeneous across member states. Our econometric analysis suggests that, within the first phase of the EU ETS, relative allowance allocation did not have a significant impact on firm performance and employment of regulated German firms

Efficient SPECT scatter calculation in non-uniform media using correlated Monte Carlo simulation

International Nuclear Information System (INIS)

Beekman, F.J.

1999-01-01

Accurate simulation of scatter in projection data of single photon emission computed tomography (SPECT) is computationally extremely demanding for activity distribution in non-uniform dense media. This paper suggests how the computation time and memory requirements can be significantly reduced. First the scatter projection of a uniform dense object (P SDSE ) is calculated using a previously developed accurate and fast method which includes all orders of scatter (slab-derived scatter estimation), and then P SDSE is transformed towards the desired projection P which is based on the non-uniform object. The transform of P SDSE is based on two first-order Compton scatter Monte Carlo (MC) simulated projections. One is based on the uniform object (P u ) and the other on the object with non-uniformities (P ν ). P is estimated by P-tilde=P SDSE P ν /P u . A tremendous decrease in noise in P-tilde is achieved by tracking photon paths for P ν identical to those which were tracked for the calculation of P u and by using analytical rather than stochastic modelling of the collimator. The method was validated by comparing the results with standard MC-simulated scatter projections (P) of 99m Tc and 201 Tl point sources in a digital thorax phantom. After correction, excellent agreement was obtained between P-tilde and P. The total computation time required to calculate an accurate scatter projection of an extended distribution in a thorax phantom on a PC is a only few tens of seconds per projection, which makes the method attractive for application in accurate scatter correction in clinical SPECT. Furthermore, the method removes the need of excessive computer memory involved with previously proposed 3D model-based scatter correction methods. (author)

Secure and Efficient Access Control Scheme for Wireless Sensor Networks in the Cross-Domain Context of the IoT

Directory of Open Access Journals (Sweden)

Ming Luo

2018-01-01

Full Text Available Nowadays wireless sensor network (WSN is increasingly being used in the Internet of Things (IoT for data collection, and design of an access control scheme that allows an Internet user as part of IoT to access the WSN becomes a hot topic. A lot of access control schemes have been proposed for the WSNs in the context of the IoT. Nevertheless, almost all of these schemes assume that communication nodes in different network domains share common system parameters, which is not suitable for cross-domain IoT environment in practical situations. To solve this shortcoming, we propose a more secure and efficient access control scheme for wireless sensor networks in the cross-domain context of the Internet of Things, which allows an Internet user in a certificateless cryptography (CLC environment to communicate with a sensor node in an identity-based cryptography (IBC environment with different system parameters. Moreover, our proposed scheme achieves known session-specific temporary information security (KSSTIS that most of access control schemes cannot satisfy. Performance analysis is given to show that our scheme is well suited for wireless sensor networks in the cross-domain context of the IoT.

Test stand for non-uniformity correction of microbolometer focal plane arrays used in thermal cameras

Science.gov (United States)

Krupiński, Michał; Bareła, Jaroslaw; Firmanty, Krzysztof; Kastek, Mariusz

2013-10-01

Uneven response of particular detectors (pixels) to the same incident power of infrared radiation is an inherent feature of microbolometer focal plane arrays. As a result an image degradation occurs, known as Fixed Pattern Noise (FPN), which distorts the thermal representation of an observed scene and impairs the parameters of a thermal camera. In order to compensate such non-uniformity, several NUC correction methods are applied in digital data processing modules implemented in thermal cameras. Coefficients required to perform the non-uniformity correction procedure (NUC coefficients) are determined by calibrating the camera against uniform radiation sources (blackbodies). Non-uniformity correction is performed in a digital processing unit in order to remove FPN pattern in the registered thermal images. Relevant correction coefficients are calculated on the basis of recorded detector responses to several values of radiant flux emitted from reference IR radiation sources (blackbodies). The measurement of correction coefficients requires specialized setup, in which uniform, extended radiation sources with high temperature stability are one of key elements. Measurement stand for NUC correction developed in Institute of Optoelectronics, MUT, comprises two integrated extended blackbodies with the following specifications: area 200×200 mm, stabilized absolute temperature range +15 °C÷100 °C, and uniformity of temperature distribution across entire surface +/-0.014 °C. Test stand, method used for the measurement of NUC coefficients and the results obtained during the measurements conducted on a prototype thermal camera will be presented in the paper.

Maximum principle and convergence of central schemes based on slope limiters

KAUST Repository

Mehmetoglu, Orhan; Popov, Bojan

2012-01-01

A maximum principle and convergence of second order central schemes is proven for scalar conservation laws in dimension one. It is well known that to establish a maximum principle a nonlinear piecewise linear reconstruction is needed and a typical choice is the minmod limiter. Unfortunately, this implies that the scheme uses a first order reconstruction at local extrema. The novelty here is that we allow local nonlinear reconstructions which do not reduce to first order at local extrema and still prove maximum principle and convergence. © 2011 American Mathematical Society.

Emissions trading and competitiveness: pros and cons of relative and absolute schemes

International Nuclear Information System (INIS)

Kuik, Onno; Mulder, Machiel

2004-01-01

Emissions trading is a hot issue. At national as well as supranational levels, proposals for introduction of emissions trading schemes have been made. This paper assesses alternative emissions trading schemes at domestic level: (1) schemes where the total level of emissions is fixed (absolute cap-and-trade), (2) schemes where the allowable level of emissions per firm is related to some firm-specific indicator (relative cap-and-trade), and (3) mixed schemes which combine elements of the above alternatives. We present a quantitative assessment of these alternatives for climate change policy in the Netherlands. It is concluded that while relative cap-and-trade would avoid negative effects on competitiveness, it would not reduce emissions at the lowest costs. Besides, the addition of a trade system to existing relative standards does not result in additional emission reduction; it should be combined with other policy measures, such as energy taxes, in order to realise further reduction. Absolute cap-and-trade leads to efficient emissions reduction, but, implemented at the national level, its overall macroeconomic costs may be significant. The mixed scheme has as drawback that it treats firms unequal, which leads to high administrative costs. We conclude that none of the trading schemes is an advisable instrument for domestic climate policy

A predictive control scheme for real-time demand response applications

NARCIS (Netherlands)

Lampropoulos, I.; Baghina, N.G.; Kling, W.L.; Ribeiro, P.F.

2013-01-01

In this work, the focus is placed on the proof of concept of a novel control scheme for demand response. The control architecture considers a uniform representation of non-homogeneous distributed energy resources and allows the participation of virtually all system users in electricity markets. The

Physical correction model for automatic correction of intensity non-uniformity in magnetic resonance imaging

Directory of Open Access Journals (Sweden)

Stefan Leger

2017-10-01

Conclusion: The proposed PCM algorithm led to a significantly improved image quality compared to the originally acquired images, suggesting that it is applicable to the correction of MRI data. Thus it may help to reduce intensity non-uniformity which is an important step for advanced image analysis.

Dust grain dynamics due to nonuniform and nonstationary high-frequency radiations in cold magnetoplasmas

Directory of Open Access Journals (Sweden)

A. K. Nekrasov

2006-03-01

Full Text Available A general nonlinear theory for low-frequency electromagnetic field generation due to high-frequency nonuniform and nonstationary electromagnetic radiations in cold, uniform, multicomponent, dusty magnetoplasmas is developed. This theory permits us to consider the nonlinear action of all waves that can exist in such plasmas. The equations are derived for the dust grain velocities in the low-frequency nonlinear electric fields arising due to the presence of electromagnetic cyclotron waves travelling along the background magnetic field. The dust grains are considered to be magnetized as well as unmagnetized. Different regimes for the dust particle dynamics, depending on the spatio-temporal change of the wave amplitudes and plasma parameters, are discussed. It is shown that induced nonlinear electric fields can have both an electrostatic and electromagnetic nature. Conditions for maximum dust acceleration are found. The results obtained may be useful for understanding the possible mechanisms of dust grain dynamics in astrophysical, cosmic and laboratory plasmas under the action of nonuniform and nonstationary electromagnetic waves.

An optimized cosine-modulated nonuniform filter bank design for subband coding of ECG signal

Directory of Open Access Journals (Sweden)

A. Kumar

2015-07-01

Full Text Available A simple iterative technique for the design of nonuniform cosine modulated filter banks (CMFBS is presented in this paper. The proposed technique employs a single parameter for optimization. The nonuniform cosine modulated filter banks are derived by merging the adjacent filters of uniform cosine modulated filter banks. The prototype filter is designed with the aid of different adjustable window functions such as Kaiser, Cosh and Exponential, and by using the constrained equiripple finite impulse response (FIR digital filter design technique. In this method, either cut off frequency or passband edge frequency is varied in order to adjust the filter coefficients so that reconstruction error could be optimized/minimized to zero. Performance and effectiveness of the proposed method in terms of peak reconstruction error (PRE, aliasing distortion (AD, computational (CPU time, and number of iteration (NOI have been shown through the numerical examples and comparative studies. Finally, the technique is exploited for the subband coding of electrocardiogram (ECG and speech signals.

Equidistribution for Nonuniformly Expanding Dynamical Systems, and Application to the Almost Sure Invariance Principle

Science.gov (United States)

Korepanov, Alexey

2017-12-01

Let {T : M \\to M} be a nonuniformly expanding dynamical system, such as logistic or intermittent map. Let {v : M \\to R^d} be an observable and {v_n = \\sum_{k=0}^{n-1} v circ T^k} denote the Birkhoff sums. Given a probability measure {μ} on M, we consider v n as a discrete time random process on the probability space {(M, μ)} . In smooth ergodic theory there are various natural choices of {μ} , such as the Lebesgue measure, or the absolutely continuous T-invariant measure. They give rise to different random processes. We investigate relation between such processes. We show that in a large class of measures, it is possible to couple (redefine on a new probability space) every two processes so that they are almost surely close to each other, with explicit estimates of "closeness". The purpose of this work is to close a gap in the proof of the almost sure invariance principle for nonuniformly hyperbolic transformations by Melbourne and Nicol.

The importance of non-uniform dose-distribution in an organ

International Nuclear Information System (INIS)

Richmond, C.R.

1975-01-01

The recent revival of interest in the 'hot particle' problem, especially as regards particulate plutonium and other actinide elements in the lung, stimulated the preparation of this paper. Non-uniformity of dose-distribution has been of concern to standards-setting bodies and other groups such as the National Academy of Sciences and to health protectionists for many years. This paper reviews data from animal experiments that are used by some to implicate particulate plutonium as being especially hazardous to man. Other relevant biological data are also discussed. (author)

Analyte preconcentration in nanofluidic channels with nonuniform zeta potential

Science.gov (United States)

Eden, A.; McCallum, C.; Storey, B. D.; Pennathur, S.; Meinhart, C. D.

2017-12-01

It is well known that charged analytes in the presence of nonuniform electric fields concentrate at locations where the relevant driving forces balance, and a wide range of ionic stacking and focusing methods are commonly employed to leverage these physical mechanisms in order to improve signal levels in biosensing applications. In particular, nanofluidic channels with spatially varying conductivity distributions have been shown to provide increased preconcentration of charged analytes due to the existence of a finite electric double layer (EDL), in which electrostatic attraction and repulsion from charged surfaces produce nonuniform transverse ion distributions. In this work, we use numerical simulations to show that one can achieve greater levels of sample accumulation by using field-effect control via wall-embedded electrodes to tailor the surface potential heterogeneity in a nanochannel with overlapped EDLs. In addition to previously demonstrated stacking and focusing mechanisms, we find that the coupling between two-dimensional ion distributions and the axial electric field under overlapped EDL conditions can generate an ion concentration polarization interface in the middle of the channel. Under an applied electric field, this interface can be used to concentrate sample ions between two stationary regions of different surface potential and charge density. Our numerical model uses the Poisson-Nernst-Planck system of equations coupled with the Stokes equation to demonstrate the phenomenon, and we discuss in detail the driving forces behind the predicted sample enhancement. The numerical velocity and salt concentration profiles exhibit good agreement with analytical results from a simplified one-dimensional area-averaged model for several limiting cases, and we show predicted amplification ratios of up to 105.

AN ADVANCED LEAKAGE SCHEME FOR NEUTRINO TREATMENT IN ASTROPHYSICAL SIMULATIONS

Energy Technology Data Exchange (ETDEWEB)

Perego, A. [Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 2, D-64289 Darmstadt (Germany); Cabezón, R. M. [Physics Department, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Käppeli, R., E-mail: albino.perego@physik.tu-darmstadt.de [Seminar for Applied Mathematics, ETH Zürich, Rämistrasse 101, 8092 Zürich (Switzerland)

2016-04-15

We present an Advanced Spectral Leakage (ASL) scheme to model neutrinos in the context of core-collapse supernovae (CCSNe) and compact binary mergers. Based on previous gray leakage schemes, the ASL scheme computes the neutrino cooling rates by interpolating local production and diffusion rates (relevant in optically thin and thick regimes, respectively) separately for discretized values of the neutrino energy. Neutrino trapped components are also modeled, based on equilibrium and timescale arguments. The better accuracy achieved by the spectral treatment allows a more reliable computation of neutrino heating rates in optically thin conditions. The scheme has been calibrated and tested against Boltzmann transport in the context of Newtonian spherically symmetric models of CCSNe. ASL shows a very good qualitative and a partial quantitative agreement for key quantities from collapse to a few hundreds of milliseconds after core bounce. We have proved the adaptability and flexibility of our ASL scheme, coupling it to an axisymmetric Eulerian and to a three-dimensional smoothed particle hydrodynamics code to simulate core collapse. Therefore, the neutrino treatment presented here is ideal for large parameter-space explorations, parametric studies, high-resolution tests, code developments, and long-term modeling of asymmetric configurations, where more detailed neutrino treatments are not available or are currently computationally too expensive.

An improved anonymous authentication scheme for roaming in ubiquitous networks

Science.gov (United States)

Lee, Hakjun; Lee, Donghoon; Moon, Jongho; Jung, Jaewook; Kang, Dongwoo; Kim, Hyoungshick

2018-01-01

With the evolution of communication technology and the exponential increase of mobile devices, the ubiquitous networking allows people to use our data and computing resources anytime and everywhere. However, numerous security concerns and complicated requirements arise as these ubiquitous networks are deployed throughout people’s lives. To meet the challenge, the user authentication schemes in ubiquitous networks should ensure the essential security properties for the preservation of the privacy with low computational cost. In 2017, Chaudhry et al. proposed a password-based authentication scheme for the roaming in ubiquitous networks to enhance the security. Unfortunately, we found that their scheme remains insecure in its protection of the user privacy. In this paper, we prove that Chaudhry et al.’s scheme is vulnerable to the stolen-mobile device and user impersonation attacks, and its drawbacks comprise the absence of the incorrect login-input detection, the incorrectness of the password change phase, and the absence of the revocation provision. Moreover, we suggest a possible way to fix the security flaw in Chaudhry et al’s scheme by using the biometric-based authentication for which the bio-hash is applied in the implementation of a three-factor authentication. We prove the security of the proposed scheme with the random oracle model and formally verify its security properties using a tool named ProVerif, and analyze it in terms of the computational and communication cost. The analysis result shows that the proposed scheme is suitable for resource-constrained ubiquitous environments. PMID:29505575

Improved Seasonal Prediction of European Summer Temperatures With New Five-Layer Soil-Hydrology Scheme

Science.gov (United States)

Bunzel, Felix; Müller, Wolfgang A.; Dobrynin, Mikhail; Fröhlich, Kristina; Hagemann, Stefan; Pohlmann, Holger; Stacke, Tobias; Baehr, Johanna

2018-01-01

We evaluate the impact of a new five-layer soil-hydrology scheme on seasonal hindcast skill of 2 m temperatures over Europe obtained with the Max Planck Institute Earth System Model (MPI-ESM). Assimilation experiments from 1981 to 2010 and 10-member seasonal hindcasts initialized on 1 May each year are performed with MPI-ESM in two soil configurations, one using a bucket scheme and one a new five-layer soil-hydrology scheme. We find the seasonal hindcast skill for European summer temperatures to improve with the five-layer scheme compared to the bucket scheme and investigate possible causes for these improvements. First, improved indirect soil moisture assimilation allows for enhanced soil moisture-temperature feedbacks in the hindcasts. Additionally, this leads to improved prediction of anomalies in the 500 hPa geopotential height surface, reflecting more realistic atmospheric circulation patterns over Europe.

Optimal Tradable Credits Scheme and Congestion Pricing with the Efficiency Analysis to Congestion

Directory of Open Access Journals (Sweden)

Ge Gao

2015-01-01

Full Text Available We allow for three traffic scenarios: the tradable credits scheme, congestion pricing, and no traffic measure. The utility functions of different modes (car, bus, and bicycle are developed by considering the income’s impact on travelers’ behaviors. Their purpose is to analyze the demand distribution of different modes. A social optimization model is built aiming at maximizing the social welfare. The optimal tradable credits scheme (distribution of credits, credits charging, and the credit price, congestion pricing fees, bus frequency, and bus fare are obtained by solving the model. Mode choice behavior under the tradable credits scheme is also studied. Numerical examples are presented to demonstrate the model’s availability and explore the effects of the three schemes on traffic system’s performance. Results show congestion pricing would earn more social welfare than the other traffic measures. However, tradable credits scheme will give travelers more consumer surplus than congestion pricing. Travelers’ consumer surplus with congestion pricing is the minimum, which injures the travelers’ benefits. Tradable credits scheme is considered the best scenario by comparing the three scenarios’ efficiency.

New Financing Schemes of Public Infrastructure

Directory of Open Access Journals (Sweden)

Ignacio de la Riva

2017-01-01

Full Text Available Public works procurements and concessions are traditional legal techniques used to shape the financing of public infrastructure. Fiscal constraints faced by public administrations at the end of the 20th century, and the subsequent increase of private participation in the provision of public goods and services, encouraged the development of new legal schemes allowing a higher degree of private investment in public infrastructure; such as Public Private Partnerships, project finance, securitizations, the shadow toll, turn-key agreements, public leasing and public trusts.

Jeans Instability of the Self-Gravitating Viscoelastic Ferromagnetic Cylinder with Axial Nonuniform Rotation and Magnetic Field

Science.gov (United States)

Dhiman, Joginder Singh; Sharma, Rajni

2017-12-01

The effects of nonuniform rotation and magnetic field on the instability of a self gravitating infinitely extending axisymmetric cylinder of viscoelastic ferromagnetic medium have been studied using the Generalised Hydrodynamic (GH) model. The non-uniform magnetic field and rotation are acting along the axial direction of the cylinder and the propagation of the wave is considered along the radial direction, while the ferrofluid magnetization is taken collinear with the magnetic field. A general dispersion relation representing magnetization, magnetic permeability and viscoelastic relaxation time parameters is obtained using the normal mode analysis method in the linearized perturbation equation system. Jeans criteria which represent the onset of instability of self gravitating medium are obtained under the limits; when the medium behaves like a viscous liquid (strongly coupled limit) and a Newtonian liquid (weakly coupled limit). The effects of various parameters on the Jeans instability criteria and on the growth rate of self gravitating viscoelastic ferromagnetic medium have been discussed. It is found that the magnetic polarizability due to ferromagnetization of medium marginalizes the effect of non-uniform magnetic field on the Jeans instability, whereas the viscoelasticity of the medium has the usual stabilizing effect on the instability of the system. Further, it is found that the cylindrical geometry is more stable than the Cartesian one. The variation of growth rate against the wave number and radial distance has been depicted graphically.

Prediction-based association control scheme in dense femtocell networks

Science.gov (United States)

Pham, Ngoc-Thai; Huynh, Thong; Hwang, Won-Joo; You, Ilsun; Choo, Kim-Kwang Raymond

2017-01-01

The deployment of large number of femtocell base stations allows us to extend the coverage and efficiently utilize resources in a low cost manner. However, the small cell size of femtocell networks can result in frequent handovers to the mobile user, and consequently throughput degradation. Thus, in this paper, we propose predictive association control schemes to improve the system’s effective throughput. Our design focuses on reducing handover frequency without impacting on throughput. The proposed schemes determine handover decisions that contribute most to the network throughput and are proper for distributed implementations. The simulation results show significant gains compared with existing methods in terms of handover frequency and network throughput perspective. PMID:28328992

Study of response nonuniformity for the LHCb calorimeter module and the prototype of the CBM calorimeter module

International Nuclear Information System (INIS)

Korolko, I. E.; Prokudin, M. S.

2009-01-01

A spatial nonuniformity of the response to high-energy muons is studied in the modules of the LHCb electromagnetic calorimeter and the prototype of the calorimeter module with lead plates and scintillator tiles 0.5 mm thick. The nonuniformity of the response of the inner LHCb modules to 50-GeV electrons is also measured. Software is developed for a thorough simulation of light collection in scintillator plates of a shashlik calorimeter. A model is elaborated to describe light transmission from the initial scintillation to the wavelength-shifting fiber with a subsequent reradiation and propagation of light over the fiber to the photodetector. The results of the simulation are in good agreement with data.

Development and test of a classification scheme for human factors in incident reports

International Nuclear Information System (INIS)

Miller, R.; Freitag, M.; Wilpert, B.

1997-01-01

The Research Center System Safety of the Berlin University of Technology conducted a research project on the analysis of Human Factors (HF) aspects in incident reported by German Nuclear Power Plants. Based on psychological theories and empirical studies a classification scheme was developed which permits the identification of human involvement in incidents. The classification scheme was applied in an epidemiological study to a selection of more than 600 HF - relevant incidents. The results allow insights into HF related problem areas. An additional study proved that the application of the classification scheme produces results which are reliable and independent from raters. (author). 13 refs, 1 fig

Linear kinetic enlightenment of a slab of nonuniform plasma

International Nuclear Information System (INIS)

Revenchuk, S.M.

1996-01-01

A phenomenon of linear kinetic regeneration of a harmonic electric-field perturbation beyond the nonuniform opacity barrier due to electrons trapped by a potential well is investigated. Such electrons are reflected by the well walls without loss of phase memory about the external perturbation, which is rehabilitated on the other side of the barrier. The incidence of the electromagnetic wave polarized in the plane of incidence on a plasma slab. Analytic expressions for the regenerated electric field and regeneration coefficient are obtained in the ballistic approximation. The dependence of the regeneration coefficient on shape of the electrostatic potential confining the wave barrier is discussed

Effect of annealing, thickness ratio and bend angle on springback of AA6061-T6 with non-uniform thickness section

Directory of Open Access Journals (Sweden)

Adnan M.F.

2017-01-01

Full Text Available Non-uniform thickness section section is considered one of the most effective approaches to reduce automotive part weight. Reduction in term of mass and size result in less fuel consumption and greenhouse gases. Thickness is the most significant parameter to formability, therefore forming a section with non-uniform thickness becomes a great challenge. Improper process and incorrect decision may lead to severe defect and one of the main concerns is the springback. This study will focus on springback behaviour of non-uniform thickness AA6061 strip with complex profile using Taguchi Method. Profile projector (PC 3000 is used to measure the spring back and two-line technique is applied to measure angles (after loading between two lines. Three parameters (i.e. annealing temperature, thickness ratio and bend angle are studied, and results determine that the most significant parameter is bend angle, followed by thickness ratio, and then by the annealing temperature of the specimen during bending process.

A New Framework to Compare Mass-Flux Schemes Within the AROME Numerical Weather Prediction Model

Science.gov (United States)

Riette, Sébastien; Lac, Christine

2016-08-01

In the Application of Research to Operations at Mesoscale (AROME) numerical weather forecast model used in operations at Météo-France, five mass-flux schemes are available to parametrize shallow convection at kilometre resolution. All but one are based on the eddy-diffusivity-mass-flux approach, and differ in entrainment/detrainment, the updraft vertical velocity equation and the closure assumption. The fifth is based on a more classical mass-flux approach. Screen-level scores obtained with these schemes show few discrepancies and are not sufficient to highlight behaviour differences. Here, we describe and use a new experimental framework, able to compare and discriminate among different schemes. For a year, daily forecast experiments were conducted over small domains centred on the five French metropolitan radio-sounding locations. Cloud base, planetary boundary-layer height and normalized vertical profiles of specific humidity, potential temperature, wind speed and cloud condensate were compared with observations, and with each other. The framework allowed the behaviour of the different schemes in and above the boundary layer to be characterized. In particular, the impact of the entrainment/detrainment formulation, closure assumption and cloud scheme were clearly visible. Differences mainly concerned the transport intensity thus allowing schemes to be separated into two groups, with stronger or weaker updrafts. In the AROME model (with all interactions and the possible existence of compensating errors), evaluation diagnostics gave the advantage to the first group.

An adjoint-based scheme for eigenvalue error improvement

International Nuclear Information System (INIS)

Merton, S.R.; Smedley-Stevenson, R.P.; Pain, C.C.; El-Sheikh, A.H.; Buchan, A.G.

2011-01-01

A scheme for improving the accuracy and reducing the error in eigenvalue calculations is presented. Using a rst order Taylor series expansion of both the eigenvalue solution and the residual of the governing equation, an approximation to the error in the eigenvalue is derived. This is done using a convolution of the equation residual and adjoint solution, which is calculated in-line with the primal solution. A defect correction on the solution is then performed in which the approximation to the error is used to apply a correction to the eigenvalue. The method is shown to dramatically improve convergence of the eigenvalue. The equation for the eigenvalue is shown to simplify when certain normalizations are applied to the eigenvector. Two such normalizations are considered; the rst of these is a fission-source type of normalisation and the second is an eigenvector normalisation. Results are demonstrated on a number of demanding elliptic problems using continuous Galerkin weighted nite elements. Moreover, the correction scheme may also be applied to hyperbolic problems and arbitrary discretization. This is not limited to spatial corrections and may be used throughout the phase space of the discrete equation. The applied correction not only improves fidelity of the calculation, it allows assessment of the reliability of numerical schemes to be made and could be used to guide mesh adaption algorithms or to automate mesh generation schemes. (author)

Unified analytical threshold voltage model for non-uniformly doped dual metal gate fully depleted silicon-on-insulator MOSFETs

Science.gov (United States)

Rao, Rathnamala; Katti, Guruprasad; Havaldar, Dnyanesh S.; DasGupta, Nandita; DasGupta, Amitava

2009-03-01

The paper describes the unified analytical threshold voltage model for non-uniformly doped, dual metal gate (DMG) fully depleted silicon-on-insulator (FDSOI) MOSFETs based on the solution of 2D Poisson's equation. 2D Poisson's equation is solved analytically for appropriate boundary conditions using separation of variables technique. The solution is then extended to obtain the threshold voltage of the FDSOI MOSFET. The model is able to handle any kind of non-uniform doping, viz. vertical, lateral as well as laterally asymetric channel (LAC) profile in the SOI film in addition to the DMG structure. The analytical results are validated with the numerical simulations using the device simulator MEDICI.

Secure Dynamic access control scheme of PHR in cloud computing.

Science.gov (United States)

Chen, Tzer-Shyong; Liu, Chia-Hui; Chen, Tzer-Long; Chen, Chin-Sheng; Bau, Jian-Guo; Lin, Tzu-Ching

2012-12-01

With the development of information technology and medical technology, medical information has been developed from traditional paper records into electronic medical records, which have now been widely applied. The new-style medical information exchange system "personal health records (PHR)" is gradually developed. PHR is a kind of health records maintained and recorded by individuals. An ideal personal health record could integrate personal medical information from different sources and provide complete and correct personal health and medical summary through the Internet or portable media under the requirements of security and privacy. A lot of personal health records are being utilized. The patient-centered PHR information exchange system allows the public autonomously maintain and manage personal health records. Such management is convenient for storing, accessing, and sharing personal medical records. With the emergence of Cloud computing, PHR service has been transferred to storing data into Cloud servers that the resources could be flexibly utilized and the operation cost can be reduced. Nevertheless, patients would face privacy problem when storing PHR data into Cloud. Besides, it requires a secure protection scheme to encrypt the medical records of each patient for storing PHR into Cloud server. In the encryption process, it would be a challenge to achieve accurately accessing to medical records and corresponding to flexibility and efficiency. A new PHR access control scheme under Cloud computing environments is proposed in this study. With Lagrange interpolation polynomial to establish a secure and effective PHR information access scheme, it allows to accurately access to PHR with security and is suitable for enormous multi-users. Moreover, this scheme also dynamically supports multi-users in Cloud computing environments with personal privacy and offers legal authorities to access to PHR. From security and effectiveness analyses, the proposed PHR access

Setting aside Transactions from Pyramid Schemes as Impeachable Dispositions under South African Insolvency Legislation

Directory of Open Access Journals (Sweden)

Zingapi Mabe

2016-10-01

Full Text Available South African courts have experienced a rise in the number of cases involving schemes that promise a return on investment with interest rates which are considerably above the maximum amount allowed by law, or schemes which promise compensation from the active recruitment of participants. These schemes, which are often referred to as pyramid or Ponzi schemes, are unsustainable operations and give rise to problems in the law of insolvency. Investors in these schemes are often left empty-handed upon the scheme’s eventual collapse and insolvency. Investors who received pay-outs from the scheme find themselves in the defence against the trustee’s claims for the return of the pay-outs to the insolvent estate. As the schemes are illegal and the pay-outs are often in terms of void agreements, the question arises whether they can be returned to the insolvent estate. A similar situation arose in Griffiths v Janse van Rensburg 2015 ZASCA 158 (26 October 2015. The point of contention in this case was whether the illegality of the business of the scheme was a relevant consideration in determining whether the pay-outs were made in the ordinary course of business of the scheme. This paper discusses pyramid schemes in the context of impeachable dispositions in terms of the Insolvency Act 24 of 1936.

Adaptive protection scheme

Directory of Open Access Journals (Sweden)

R. Sitharthan

2016-09-01

Full Text Available This paper aims at modelling an electronically coupled distributed energy resource with an adaptive protection scheme. The electronically coupled distributed energy resource is a microgrid framework formed by coupling the renewable energy source electronically. Further, the proposed adaptive protection scheme provides a suitable protection to the microgrid for various fault conditions irrespective of the operating mode of the microgrid: namely, grid connected mode and islanded mode. The outstanding aspect of the developed adaptive protection scheme is that it monitors the microgrid and instantly updates relay fault current according to the variations that occur in the system. The proposed adaptive protection scheme also employs auto reclosures, through which the proposed adaptive protection scheme recovers faster from the fault and thereby increases the consistency of the microgrid. The effectiveness of the proposed adaptive protection is studied through the time domain simulations carried out in the PSCAD⧹EMTDC software environment.

Implementation of a european directive establishing a negotiable CO2 emissions trading scheme

International Nuclear Information System (INIS)

Coussy, P.

2003-01-01

Approved on July 22, 2003, European Directive 87/2003/EC establishes a scheme for the trading of greenhouse gas emissions allowances. Before the market comes into effect on January 1, 2005, industrialists will have to account for a new financial asset in planning development strategy: the CO 2 allowance. Each Member State is currently developing a climate plan that includes the allocation of CO 2 emissions allowances to industrial installations. It will not be possible to exceed these allowances without incurring a financial penalty. (author)

Comparative study of numerical schemes of TVD3, UNO3-ACM and optimized compact scheme

Science.gov (United States)

Lee, Duck-Joo; Hwang, Chang-Jeon; Ko, Duck-Kon; Kim, Jae-Wook

1995-01-01

Three different schemes are employed to solve the benchmark problem. The first one is a conventional TVD-MUSCL (Monotone Upwind Schemes for Conservation Laws) scheme. The second scheme is a UNO3-ACM (Uniformly Non-Oscillatory Artificial Compression Method) scheme. The third scheme is an optimized compact finite difference scheme modified by us: the 4th order Runge Kutta time stepping, the 4th order pentadiagonal compact spatial discretization with the maximum resolution characteristics. The problems of category 1 are solved by using the second (UNO3-ACM) and third (Optimized Compact) schemes. The problems of category 2 are solved by using the first (TVD3) and second (UNO3-ACM) schemes. The problem of category 5 is solved by using the first (TVD3) scheme. It can be concluded from the present calculations that the Optimized Compact scheme and the UN03-ACM show good resolutions for category 1 and category 2 respectively.

Regional allocation of CO2 emissions allowance over provinces in China by 2020

International Nuclear Information System (INIS)

Wang, Ke; Zhang, Xian; Wei, Yi-Ming; Yu, Shiwei

2013-01-01

The mitigation efforts of China are increasingly important for meeting global climate target since the rapid economic growth of China has led to an increasing share in the world's total CO 2 emissions. This paper sets out to explore the approach for realizing China's national mitigation targets submitted to the UNFCCC as part of the Copenhagen Accord; that is, to reduce the intensity of CO 2 emissions per unit of GDP by 40–45% by 2020, as well as reducing the energy intensity and increasing the share of non-fossil fuel consumption, through regional allocation of emission allowance over China's provinces. Since the realization of China's mitigation target essentially represents a total amount emission allowance allocation problem, an improved zero sum gains data envelopment analysis optimization model, which could deal with the constant total amount resources allocation, is proposed in this study. By utilizing this model and based on several scenarios of China's economic growth, CO 2 emissions, and energy consumption, a new efficient emission allowance allocation scheme on provincial level for China by 2020 is proposed. The allocation results indicate that different provinces have to shoulder different mitigation burdens in terms of emission intensity reduction, energy intensity reduction, and share of non-fossil fuels increase. - Highlights: ► We explore the approach to realize national CO 2 emissions reduction target of China by 2020. ► The CO 2 emissions allowance is allocated over China's 30 administrative regions. ► Several scenarios of China's regional economy, emission, energy consumption are given. ► The zero sum gains data envelopment analysis model is applied in emission allowance allocation. ► An efficient emission allowance allocation scheme on provincial level is proposed

A parametric transfer function methodology for analyzing reactive transport in nonuniform flow.

Science.gov (United States)

Luo, Jian; Cirpka, Olaf A; Fienen, Michael N; Wu, Wei-min; Mehlhorn, Tonia L; Carley, Jack; Jardine, Philip M; Criddle, Craig S; Kitanidis, Peter K

2006-02-01

We analyze reactive transport during in-situ bioremediation in a nonuniform flow field, involving multiple extraction and injection wells, by the method of transfer functions. Gamma distributions are used as parametric models of the transfer functions. Apparent parameters of classical transport models may be estimated from those of the gamma distributions by matching temporal moments. We demonstrate the method by application to measured data taken at a field experiment on bioremediation conducted in a multiple-well system in Oak Ridge, TN. Breakthrough curves (BTCs) of a conservative tracer (bromide) and a reactive compound (ethanol) are measured at multi-level sampling (MLS) wells and in extraction wells. The BTCs of both compounds are jointly analyzed to estimate the first-order degradation rate of ethanol. To quantify the tracer loss, we compare the approaches of using a scaling factor and a first-order decay term. Results show that by including a scaling factor both gamma distributions and inverse-Gaussian distributions (transfer functions according to the advection-dispersion equation) are suitable to approximate the transfer functions and estimate the reactive rate coefficients for both MLS and extraction wells. However, using a first-order decay term for tracer loss fails to describe the BTCs at the extraction well, which is affected by the nonuniform distribution of travel paths.

Modelling of Spring Constant and Pull-down Voltage of Non-uniform RF MEMS Cantilever Incorporating Stress Gradient

Directory of Open Access Journals (Sweden)

Shimul Chandra SAHA

2008-11-01

Full Text Available We have presented a model for spring constant and pull-down voltage of a non-uniform radio frequency microelectromechanical systems (RF MEMS cantilever that works on electrostatic actuation. The residual stress gradient in the beam material that may arise during the fabrication process is also considered in the model. Using basic force deflection calculation of the suspended beam, a stand-alone model for the spring constant and pull-down voltage of the non-uniform cantilever is developed. To compare the model, simulation is performed using standard Finite Element Method (FEM analysis tolls from CoventorWare. The model matches very well with the FEM simulation results. The model will offer an efficient means of design, analysis, and optimization of RF MEMS cantilever switches.

Kinetics of charged particles in a high-voltage gas discharge in a nonuniform electrostatic field

Energy Technology Data Exchange (ETDEWEB)

Kolpakov, V. A., E-mail: kolpakov683@gmail.com; Krichevskii, S. V.; Markushin, M. A. [Korolev Samara National Research University (Russian Federation)

2017-01-15

A high-voltage gas discharge is of interest as a possible means of generating directed flows of low-temperature plasma in the off-electrode space distinguished by its original features [1–4]. We propose a model for calculating the trajectories of charges particles in a high-voltage gas discharge in nitrogen at a pressure of 0.15 Torr existing in a nonuniform electrostatic field and the strength of this field. Based on the results of our calculations, we supplement and refine the extensive experimental data concerning the investigation of such a discharge published in [1, 2, 5–8]; good agreement between the theory and experiment has been achieved. The discharge burning is initiated and maintained through bulk electron-impact ionization and ion–electron emission. We have determined the sizes of the cathode surface regions responsible for these processes, including the sizes of the axial zone involved in the discharge generation. The main effect determining the kinetics of charged particles consists in a sharp decrease in the strength of the field under consideration outside the interelectrode space, which allows a free motion of charges with specific energies and trajectories to be generated in it. The simulation results confirm that complex electrode systems that allow directed plasma flows to be generated at a discharge current of hundreds or thousands of milliamperes and a voltage on the electrodes of 0.3–1 kV can be implemented in practice [3, 9, 10].

The Preliminary Research for Implementation of Improved DTC Scheme of High Performance PMSM Drives

Directory of Open Access Journals (Sweden)

Tole Sutikno

2008-12-01

Full Text Available The direct torque control (DTC is one of control approache that is used commonly in PMSM control system. This method supports a very quick and precise torque response. However, the DTC method is not perfect and has some disadvantages. Many researchers have been proposed to modify the basic DTC scheme for PMSM drive. All this contributions allow performance to be improved, but at the same time they lead to more complex schemes. Furthermore, the PMSM drive control systems are usually based on microcontroller and DSP. Some researchers also have been used DSP and FPGA together to develop DTC for AC drives. These allow improving the performance, but they will increase cost. For the reason above, this paper proposed a new DTC scheme to apply only based on FPGA. The preliminary research showed that the proposed DTC sheme can reduce torque and flux ripples significantly. Therefore, this paper also recomend to realize proposed DTC scheme based on FPGA in order to support to execute very fast computation.The implementation is hoped that it will very potential to replace not only the induction motor but also the DC servo motor in a number of industrial process, commercial, domestic and modern military applications of high-performance drive.

Developing and modifying behavioral coding schemes in pediatric psychology: a practical guide.

Science.gov (United States)

Chorney, Jill MacLaren; McMurtry, C Meghan; Chambers, Christine T; Bakeman, Roger

2015-01-01

To provide a concise and practical guide to the development, modification, and use of behavioral coding schemes for observational data in pediatric psychology. This article provides a review of relevant literature and experience in developing and refining behavioral coding schemes. A step-by-step guide to developing and/or modifying behavioral coding schemes is provided. Major steps include refining a research question, developing or refining the coding manual, piloting and refining the coding manual, and implementing the coding scheme. Major tasks within each step are discussed, and pediatric psychology examples are provided throughout. Behavioral coding can be a complex and time-intensive process, but the approach is invaluable in allowing researchers to address clinically relevant research questions in ways that would not otherwise be possible. © The Author 2014. Published by Oxford University Press on behalf of the Society of Pediatric Psychology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Enhanced Security and Pairing-free Handover Authentication Scheme for Mobile Wireless Networks

Science.gov (United States)

Chen, Rui; Shu, Guangqiang; Chen, Peng; Zhang, Lijun

2017-10-01

With the widely deployment of mobile wireless networks, we aim to propose a secure and seamless handover authentication scheme that allows users to roam freely in wireless networks without worrying about security and privacy issues. Given the open characteristic of wireless networks, safety and efficiency should be considered seriously. Several previous protocols are designed based on a bilinear pairing mapping, which is time-consuming and inefficient work, as well as unsuitable for practical situations. To address these issues, we designed a new pairing-free handover authentication scheme for mobile wireless networks. This scheme is an effective improvement of the protocol by Xu et al., which is suffer from the mobile node impersonation attack. Security analysis and simulation experiment indicate that the proposed protocol has many excellent security properties when compared with other recent similar handover schemes, such as mutual authentication and resistance to known network threats, as well as requiring lower computation and communication cost.

Tunnel Face Stability and the Effectiveness of Advance Drainage Measures in Water-Bearing Ground of Non-uniform Permeability

Science.gov (United States)

Zingg, Sara; Anagnostou, Georg

2018-01-01

Non-uniform permeability may result in complex hydraulic head fields with potentially very high hydraulic gradients close to the tunnel face, which may be adverse for stability depending on the ground strength. Pore pressure relief by drainage measures in advance of the tunnel excavation improves stability, but the effectiveness of drainage boreholes may be low in the case of alternating aquifers and aquitards. This paper analyses the effects of hydraulic heterogeneity and advance drainage quantitatively by means of limit equilibrium computations that take account of the seepage forces acting upon the ground in the vicinity the tunnel face. The piezometric field is determined numerically by means of steady-state, three-dimensional seepage flow analyses considering the heterogeneous structure of the ground and a typical advance drainage scheme consisting of six axial boreholes drilled from the tunnel face. A suite of stability analyses was carried out covering a wide range of heterogeneity scales. The computational results show the effect of the orientation, thickness, location, number and permeability ratio of aquifers and aquitards and provide valuable indications about potentially critical situations, the effectiveness of advance drainage and the adequate arrangement of drainage boreholes. The paper shows that hydraulic heterogeneity results in highly variable face behaviour, even if the shear strength of the ground is constant along the alignment, but ground behaviour is considerably less variable in the presence of advance drainage measures.

A Lattice-Based Identity-Based Proxy Blind Signature Scheme in the Standard Model

Directory of Open Access Journals (Sweden)

Lili Zhang

2014-01-01

Full Text Available A proxy blind signature scheme is a special form of blind signature which allowed a designated person called proxy signer to sign on behalf of original signers without knowing the content of the message. It combines the advantages of proxy signature and blind signature. Up to date, most proxy blind signature schemes rely on hard number theory problems, discrete logarithm, and bilinear pairings. Unfortunately, the above underlying number theory problems will be solvable in the postquantum era. Lattice-based cryptography is enjoying great interest these days, due to implementation simplicity and provable security reductions. Moreover, lattice-based cryptography is believed to be hard even for quantum computers. In this paper, we present a new identity-based proxy blind signature scheme from lattices without random oracles. The new scheme is proven to be strongly unforgeable under the standard hardness assumption of the short integer solution problem (SIS and the inhomogeneous small integer solution problem (ISIS. Furthermore, the secret key size and the signature length of our scheme are invariant and much shorter than those of the previous lattice-based proxy blind signature schemes. To the best of our knowledge, our construction is the first short lattice-based identity-based proxy blind signature scheme in the standard model.

An Improvement to a Multi-Client Searchable Encryption Scheme for Boolean Queries.

Science.gov (United States)

Jiang, Han; Li, Xue; Xu, Qiuliang

2016-12-01

The migration of e-health systems to the cloud computing brings huge benefits, as same as some security risks. Searchable Encryption(SE) is a cryptography encryption scheme that can protect the confidentiality of data and utilize the encrypted data at the same time. The SE scheme proposed by Cash et al. in Crypto2013 and its follow-up work in CCS2013 are most practical SE Scheme that support Boolean queries at present. In their scheme, the data user has to generate the search tokens by the counter number one by one and interact with server repeatedly, until he meets the correct one, or goes through plenty of tokens to illustrate that there is no search result. In this paper, we make an improvement to their scheme. We allow server to send back some information and help the user to generate exact search token in the search phase. In our scheme, there are only two round interaction between server and user, and the search token has [Formula: see text] elements, where n is the keywords number in query expression, and [Formula: see text] is the minimum documents number that contains one of keyword in query expression, and the computation cost of server is [Formula: see text] modular exponentiation operation.

Hydrodynamic characteristics of steady magnetic fluid flow in a straight tube by taking into account the non-uniform distribution of mass concentration

International Nuclear Information System (INIS)

Shuchi, S.; Shimada, K.; Kamiyama, S.; Yamaguchi, H.

2002-01-01

We clarify numerically the wall friction coefficient, the distributions of velocity and shear rate, and the number of aggregated particles on steady magnetic fluid flow in a straight tube by taking into account the non-uniform distribution of mass concentration (DMC). Also the effect of DMC is clarified under the uniform and non-uniform transverse steady magnetic field. In comparison with the published data, the numerical results show good agreement with the experimental data

DYNSUB: A high fidelity coupled code system for the evaluation of local safety parameters – Part II: Comparison of different temporal schemes

International Nuclear Information System (INIS)

Gomez-Torres, Armando Miguel; Sanchez-Espinoza, Victor Hugo; Ivanov, Kostadin; Macian-Juan, Rafael

2012-01-01

Highlights: ► A fixed point iteration (FPI) is implemented in DYNSUB. ► Comparisons between the explicit scheme and the FPI are done. ► The FPI scheme allows moving from one time step to the other with converged solution. ► FPI allows the use of larger time steps without compromising the accuracy of results. ► FPI results are promising and represent an option in order to optimize calculations. -- Abstract: DYNSUB is a novel two-way pin-based coupling of the simplified transport (SP 3 ) version of DYN3D with the subchannel code SUBCHANFLOW. The new coupled code system allows for a more realistic description of the core behaviour under steady state and transients conditions, and has been widely described in Part I of this paper. Additionally to the explicit coupling developed and described in Part I, a nested loop iteration or fixed point iteration (FPI) is implemented in DYNSUB. A FPI is not an implicit scheme but approximates it by adding an iteration loop to the current explicit scheme. The advantage of the method is that it allows the use of larger time steps; however the nested loop iteration could take much more time in getting a converged solution that could be less efficient than the explicit scheme with small time steps. A comparison of the two temporal schemes is performed. The results using FPI are very promising and represent a very good option in order to optimize computational times without losing accuracy. However it is also shown that a FPI scheme can produce inaccurate results if the time step is not chosen in agreement with the analyzed transient.

Experience with nonuniform damping in the seismic analysis of nuclear plant components

International Nuclear Information System (INIS)

Winkel, B.V.; Julyk, L.J.

1983-01-01

Individual components of nuclear power plants may exhibit pronounced differences in damping magnitude. Various methods for accounting for nonuniform damping in a structural model are reviewed and evaluated. The methods are compared by solving a beam/pipe model subjected to a typical seismic ground motion. A two-degree-of-freedom variable damping parameter study is also presented. Based upon the experience of evaluating and applying the available methods, application guidelines are presented

A tuning method for nonuniform traveling-wave accelerating structures

International Nuclear Information System (INIS)

Gong Cunkui; Zheng Shuxin; Shao Jiahang; Jia Xiaoyu; Chen Huaibi

2013-01-01

The tuning method of uniform traveling-wave structures based on non-resonant perturbation field distribution measurement has been widely used in tuning both constant-impedance and constant-gradient structures. In this paper, the method of tuning nonuniform structures is proposed on the basis of the above theory. The internal reflection coefficient of each cell is obtained from analyzing the normalized voltage distribution. A numerical simulation of tuning process according to the coupled cavity chain theory has been done and the result shows each cell is in right phase advance after tuning. The method will be used in the tuning of a disk-loaded traveling-wave structure being developed at the Accelerator Laboratory, Tsinghua University. (authors)

Calibration of EBT2 film by the PDD method with scanner non-uniformity correction.

Science.gov (United States)

Chang, Liyun; Chui, Chen-Shou; Ding, Hueisch-Jy; Hwang, Ing-Ming; Ho, Sheng-Yow

2012-09-21

The EBT2 film together with a flatbed scanner is a convenient dosimetry QA tool for verification of clinical radiotherapy treatments. However, it suffers from a relatively high degree of uncertainty and a tedious film calibration process for every new lot of films, including cutting the films into several small pieces, exposing with different doses, restoring them back and selecting the proper region of interest (ROI) for each piece for curve fitting. In this work, we present a percentage depth dose (PDD) method that can accurately calibrate the EBT2 film together with the scanner non-uniformity correction and provide an easy way to perform film dosimetry. All films were scanned before and after the irradiation in one of the two homemade 2 mm thick acrylic frames (one portrait and the other landscape), which was located at a fixed position on the scan bed of an Epson 10 000XL scanner. After the pre-irradiated scan, the film was placed parallel to the beam central axis and sandwiched between six polystyrene plates (5 cm thick each), followed by irradiation of a 20 × 20 cm² 6 MV photon beam. Two different beams on times were used on two different films to deliver a dose to the film ranging from 32 to 320 cGy. After the post-irradiated scan, the net optical densities for a total of 235 points on the beam central axis on the films were auto-extracted and compared with the corresponding depth doses that were calculated through the measurement of a 0.6 cc farmer chamber and the related PDD table to perform the curve fitting. The portrait film location was selected for routine calibration, since the central beam axis on the film is parallel to the scanning direction, where non-uniformity correction is not needed (Ferreira et al 2009 Phys. Med. Biol. 54 1073-85). To perform the scanner non-uniformity calibration, the cross-beam profiles of the film were analysed by referencing the measured profiles from a Profiler™. Finally, to verify our method, the films were

Calibration of EBT2 film by the PDD method with scanner non-uniformity correction

International Nuclear Information System (INIS)

Chang Liyun; Ding, Hueisch-Jy; Chui, Chen-Shou; Hwang, Ing-Ming; Ho, Sheng-Yow

2012-01-01

The EBT2 film together with a flatbed scanner is a convenient dosimetry QA tool for verification of clinical radiotherapy treatments. However, it suffers from a relatively high degree of uncertainty and a tedious film calibration process for every new lot of films, including cutting the films into several small pieces, exposing with different doses, restoring them back and selecting the proper region of interest (ROI) for each piece for curve fitting. In this work, we present a percentage depth dose (PDD) method that can accurately calibrate the EBT2 film together with the scanner non-uniformity correction and provide an easy way to perform film dosimetry. All films were scanned before and after the irradiation in one of the two homemade 2 mm thick acrylic frames (one portrait and the other landscape), which was located at a fixed position on the scan bed of an Epson 10 000XL scanner. After the pre-irradiated scan, the film was placed parallel to the beam central axis and sandwiched between six polystyrene plates (5 cm thick each), followed by irradiation of a 20 × 20 cm 2 6 MV photon beam. Two different beams on times were used on two different films to deliver a dose to the film ranging from 32 to 320 cGy. After the post-irradiated scan, the net optical densities for a total of 235 points on the beam central axis on the films were auto-extracted and compared with the corresponding depth doses that were calculated through the measurement of a 0.6 cc farmer chamber and the related PDD table to perform the curve fitting. The portrait film location was selected for routine calibration, since the central beam axis on the film is parallel to the scanning direction, where non-uniformity correction is not needed (Ferreira et al 2009 Phys. Med. Biol. 54 1073–85). To perform the scanner non-uniformity calibration, the cross-beam profiles of the film were analysed by referencing the measured profiles from a Profiler™. Finally, to verify our method, the films were

Genetic progress in multistage dairy cattle breeding schemes using genetic markers.

Science.gov (United States)

Schrooten, C; Bovenhuis, H; van Arendonk, J A M; Bijma, P

2005-04-01

QTL explaining 5% of the additive genetic variance allowed a 35% reduction in the number of progeny tested bulls, while maintaining genetic response at the level of the base scheme. Genetic progress was up to 31.3% higher for schemes with increased embryo production and selection of embryos based on QTL information. The challenge for breeding organizations is to find the optimum breeding program with regard to additional genetic progress and additional (or reduced) cost.

Numerical analysis of blood flow in realistic arteries subjected to strong non-uniform magnetic fields

NARCIS (Netherlands)

Kenjeres, S.

2008-01-01

The paper reports on a comprehensive mathematical model for simulations of blood flow under the presence of strong non-uniform magnetic fields. The model consists of a set of Navier–Stokes equations accounting for the Lorentz and magnetisation forces, and a simplified set of Maxwell’s equations

New advection schemes for free surface flows

International Nuclear Information System (INIS)

Pavan, Sara

2016-01-01

The purpose of this thesis is to build higher order and less diffusive schemes for pollutant transport in shallow water flows or 3D free surface flows. We want robust schemes which respect the main mathematical properties of the advection equation with relatively low numerical diffusion and apply them to environmental industrial applications. Two techniques are tested in this work: a classical finite volume method and a residual distribution technique combined with a finite element method. For both methods we propose a decoupled approach since it is the most advantageous in terms of accuracy and CPU time. Concerning the first technique, a vertex-centred finite volume method is used to solve the augmented shallow water system where the numerical flux is computed through an Harten-Lax-Van Leer-Contact Riemann solver. Starting from this solution, a decoupled approach is formulated and is preferred since it allows to compute with a larger time step the advection of a tracer. This idea was inspired by Audusse, E. and Bristeau, M.O. [13]. The Monotonic Upwind Scheme for Conservation Law, combined with the decoupled approach, is then used for the second order extension in space. The wetting and drying problem is also analysed and a possible solution is presented. In the second case, the shallow water system is entirely solved using the finite element technique and the residual distribution method is applied to the solution of the tracer equation, focusing on the case of time-dependent problems. However, for consistency reasons the resolution of the continuity equation must be considered in the numerical discretization of the tracer. In order to get second order schemes for unsteady cases a predictor-corrector scheme is used in this work. A first order but less diffusive version of the predictor-corrector scheme is also introduced. Moreover, we also present a new locally semi-implicit version of the residual distribution method which, in addition to good properties in

A numerical relativity scheme for cosmological simulations

Science.gov (United States)

Daverio, David; Dirian, Yves; Mitsou, Ermis

2017-12-01

Cosmological simulations involving the fully covariant gravitational dynamics may prove relevant in understanding relativistic/non-linear features and, therefore, in taking better advantage of the upcoming large scale structure survey data. We propose a new 3  +  1 integration scheme for general relativity in the case where the matter sector contains a minimally-coupled perfect fluid field. The original feature is that we completely eliminate the fluid components through the constraint equations, thus remaining with a set of unconstrained evolution equations for the rest of the fields. This procedure does not constrain the lapse function and shift vector, so it holds in arbitrary gauge and also works for arbitrary equation of state. An important advantage of this scheme is that it allows one to define and pass an adaptation of the robustness test to the cosmological context, at least in the case of pressureless perfect fluid matter, which is the relevant one for late-time cosmology.

Light extraction in planar light-emitting diode with nonuniform current injection: model and simulation.

Science.gov (United States)

Khmyrova, Irina; Watanabe, Norikazu; Kholopova, Julia; Kovalchuk, Anatoly; Shapoval, Sergei

2014-07-20

We develop an analytical and numerical model for performing simulation of light extraction through the planar output interface of the light-emitting diodes (LEDs) with nonuniform current injection. Spatial nonuniformity of injected current is a peculiar feature of the LEDs in which top metal electrode is patterned as a mesh in order to enhance the output power of light extracted through the top surface. Basic features of the model are the bi-plane computation domain, related to other areas of numerical grid (NG) cells in these two planes, representation of light-generating layer by an ensemble of point light sources, numerical "collection" of light photons from the area limited by acceptance circle and adjustment of NG-cell areas in the computation procedure by the angle-tuned aperture function. The developed model and procedure are used to simulate spatial distributions of the output optical power as well as the total output power at different mesh pitches. The proposed model and simulation strategy can be very efficient in evaluation of the output optical performance of LEDs with periodical or symmetrical configuration of the electrodes.

An in-depth stability analysis of nonuniform FDTD combined with novel local implicitization techniques

Science.gov (United States)

Van Londersele, Arne; De Zutter, Daniël; Vande Ginste, Dries

2017-08-01

This work focuses on efficient full-wave solutions of multiscale electromagnetic problems in the time domain. Three local implicitization techniques are proposed and carefully analyzed in order to relax the traditional time step limit of the Finite-Difference Time-Domain (FDTD) method on a nonuniform, staggered, tensor product grid: Newmark, Crank-Nicolson (CN) and Alternating-Direction-Implicit (ADI) implicitization. All of them are applied in preferable directions, alike Hybrid Implicit-Explicit (HIE) methods, as to limit the rank of the sparse linear systems. Both exponential and linear stability are rigorously investigated for arbitrary grid spacings and arbitrary inhomogeneous, possibly lossy, isotropic media. Numerical examples confirm the conservation of energy inside a cavity for a million iterations if the time step is chosen below the proposed, relaxed limit. Apart from the theoretical contributions, new accomplishments such as the development of the leapfrog Alternating-Direction-Hybrid-Implicit-Explicit (ADHIE) FDTD method and a less stringent Courant-like time step limit for the conventional, fully explicit FDTD method on a nonuniform grid, have immediate practical applications.

Efficient decoupling schemes with bounded controls based on Eulerian orthogonal arrays

International Nuclear Information System (INIS)

Wocjan, Pawel

2006-01-01

The task of decoupling, i.e., removing unwanted internal couplings of a quantum system and its couplings to an environment, plays an important role in quantum control theory. There are many efficient decoupling schemes based on combinatorial concepts such as orthogonal arrays, difference schemes, and Hadamard matrices. So far these combinatorial decoupling schemes have relied on the ability to effect sequences of instantaneous, arbitrarily strong control Hamiltonians (bang-bang controls). To overcome the shortcomings of bang-bang control, Viola and Knill proposed a method called 'Eulerian decoupling' that allows the use of bounded-strength controls for decoupling. However, their method was not directly designed to take advantage of the local structure of internal couplings and couplings to an environment that typically occur in multipartite quantum systems. In this paper we define a combinatorial structure called Eulerian orthogonal array. It merges the desirable properties of orthogonal arrays and Eulerian cycles in Cayley graphs (that are the basis of Eulerian decoupling). We show that this structure gives rise to decoupling schemes with bounded-strength control Hamiltonians that can be used to remove both internal couplings and couplings to an environment of a multipartite quantum system. Furthermore, we show how to construct Eulerian orthogonal arrays having good parameters in order to obtain efficient decoupling schemes

The construction of Shenzhen's carbon emission trading scheme

International Nuclear Information System (INIS)

Jiang, Jing Jing; Ye, Bin; Ma, Xiao Ming

2014-01-01

The Shenzhen ETS is the first urban-level “cap-and-trade” carbon emissions trading scheme to operate in China. This paper gives an overview of the economic and emissions situation in Shenzhen and focuses on the development of the Shenzhen ETS regulatory framework. It is devised as an ETS with an intensity-based cap, output-based allocation and a market for trading of allowances. The design of the Shenzhen ETS attaches great importance to coordinate the dynamic relationships between economic growth, industrial transition and emissions control. The cap and its allocation are determined by carbon intensity reduction targets and economic output, with an aim to slow down emissions growth while mitigating shocks from economic fluctuation and industrial adjustment to market stability. The Shenzhen ETS features extensive coverage consisting of three types of regulated entities and four categories of covered emissions, in order to control carbon emissions by both improving energy efficiency and restraining growing energy demand. A competitive game theory method is created for allocation of free allowances to manufacturing enterprises. Mechanisms for carbon offsets and market stabilization are developed to promote active and orderly trading in the carbon market. Moreover, several challenges and their policy choices are detailed for the development of the Shenzhen ETS. - Highlights: • The Shenzhen ETS is the first urban-level “cap-and-trade” carbon emission trading scheme operated in China. • This paper focuses on the construction of Shenzhen carbon emission trading scheme. It is devised as the intensity-based cap, output-based allocation and allowance trade carbon market. • It has some signatures in the general principles, coverage and scope, cap and allocation and other mechanisms. • Several challenges and their policy choices are detailed for the development of Shenzhen ETS

A method for real time detecting of non-uniform magnetic field

Science.gov (United States)

Marusenkov, Andriy

2015-04-01

The principle of measuring magnetic signatures for observing diverse objects is widely used in Near Surface work (unexploded ordnance (UXO); engineering & environmental; archaeology) and security and vehicle detection systems as well. As a rule, the magnitude of the signals to be measured is much lower than that of the quasi-uniform Earth magnetic field. Usually magnetometers for these purposes contain two or more spatially separated sensors to estimate the full tensor gradient of the magnetic field or, more frequently, only partial gradient components. The both types (scalar and vector) of magnetic sensors could be used. The identity of the scale factors and proper alignment of the sensitivity axes of the vector sensors are very important for deep suppression of the ambient field and detection of weak target signals. As a rule, the periodical calibration procedure is used to keep matching sensors' parameters as close as possible. In the present report we propose the technique for detection magnetic anomalies, which is almost insensitive to imperfect matching of the sensors. This method based on the idea that the difference signals between two sensors are considerably different when the instrument is rotated or moved in uniform and non-uniform fields. Due to the misfit of calibration parameters the difference signal observed at the rotation in the uniform field is similar to the total signal - the sum of the signals of both sensors. Zero change of the difference and total signals is expected, if the instrument moves in the uniform field along a straight line. In contrast, the same move in the non-uniform field produces some response of each of the sensors. In case one measures dB/dx and moves along x direction, the sensors signals is shifted in time with the lag proportional to the distance between sensors and the speed of move. It means that the difference signal looks like derivative of the total signal at move in the non-uniform field. So, using quite simple

A non-uniform three-gap buncher cavity with suppression of transverse-electromagnetic mode leakage in the triaxial klystron amplifier

Energy Technology Data Exchange (ETDEWEB)

Qi, Zumin; Zhang, Jun, E-mail: zhangjun-nudt@126.com; Zhong, Huihuang; Zhu, Danni; Qiu, Yongfeng [College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, Hunan 410073 (China)

2014-01-15

The triaxial klystron amplifier is an efficient high power relativistic klystron amplifier operating at high frequencies due to its coaxial structure with large radius. However, the coaxial structures result in coupling problems among the cavities as the TEM mode is not cut-off in the coaxial tube. Therefore, the suppression of the TEM mode leakage, especially the leakage from the buncher cavity to the input cavity, is crucial in the design of a triaxial klystron amplifier. In this paper, a non-uniform three-gap buncher cavity is proposed to suppress the TEM mode leakage. The cold cavity analysis shows that the non-uniform three-gap buncher cavity can significantly suppress the TEM mode generation compared to a uniform three-gap buncher cavity. Particle-in-cell simulation shows that the power leakage to the input cavity is less than 1.5‰ of the negative power in the buncher cavity and the buncher cavity can efficiently modulate an intense relativistic electron beam free of self-oscillations. A fundamental current modulation depth of 117% is achieved by employing the proposed non-uniform buncher cavity into an X-band triaxial amplifier, which results in the high efficiency generation of high power microwave.

'Massfunktionen' as limit conditions of an optimization scheme for the telecobalt therapy

International Nuclear Information System (INIS)

Kirsch, M.; Forth, E.; Schumann, E.

1978-01-01

The basic ideas of the 'Score-Funktionen-Modell' of Hope and his collaborators are used for the establishment of the first stage of an optimization scheme for the telecobalt therapy. The new 'Massfunktionen' for the telecobalt therapy are limit conditions for the criterion of the optimum, i.e. the dose distribution in a body section. The 'Massfunktionen' are an analytic registration of parameters for the dose distribution such as dose homogeneity in the focal region and sparing of the subcutaneous tissues, the radiosensitive organs and the sound surroundings of the tumor. The functions are derived from the dose conditions in the irradiated body section. At the actual stage of development of the optimization scheme, these functions allow to decide whether an irradiation scheme is acceptable or not. (orig.) [de

Random noise attenuation of non-uniformly sampled 3D seismic data along two spatial coordinates using non-equispaced curvelet transform

Science.gov (United States)

Zhang, Hua; Yang, Hui; Li, Hongxing; Huang, Guangnan; Ding, Zheyi

2018-04-01

The attenuation of random noise is important for improving the signal to noise ratio (SNR). However, the precondition for most conventional denoising methods is that the noisy data must be sampled on a uniform grid, making the conventional methods unsuitable for non-uniformly sampled data. In this paper, a denoising method capable of regularizing the noisy data from a non-uniform grid to a specified uniform grid is proposed. Firstly, the denoising method is performed for every time slice extracted from the 3D noisy data along the source and receiver directions, then the 2D non-equispaced fast Fourier transform (NFFT) is introduced in the conventional fast discrete curvelet transform (FDCT). The non-equispaced fast discrete curvelet transform (NFDCT) can be achieved based on the regularized inversion of an operator that links the uniformly sampled curvelet coefficients to the non-uniformly sampled noisy data. The uniform curvelet coefficients can be calculated by using the inversion algorithm of the spectral projected-gradient for ℓ1-norm problems. Then local threshold factors are chosen for the uniform curvelet coefficients for each decomposition scale, and effective curvelet coefficients are obtained respectively for each scale. Finally, the conventional inverse FDCT is applied to the effective curvelet coefficients. This completes the proposed 3D denoising method using the non-equispaced curvelet transform in the source-receiver domain. The examples for synthetic data and real data reveal the effectiveness of the proposed approach in applications to noise attenuation for non-uniformly sampled data compared with the conventional FDCT method and wavelet transformation.

Heat transfer in boundary layer stagnation-point flow towards a shrinking sheet with non-uniform heat flux

International Nuclear Information System (INIS)

Bhattacharyya Krishnendu

2013-01-01

In this paper, the effect of non-uniform heat flux on heat transfer in boundary layer stagnation-point flow over a shrinking sheet is studied. The variable boundary heat fluxes are considered of two types: direct power-law variation with the distance along the sheet and inverse power-law variation with the distance. The governing partial differential equations (PDEs) are transformed into non linear self-similar ordinary differential equations (ODEs) by similarity transformations, and then those are solved using very efficient shooting method. The direct variation and inverse variation of heat flux along the sheet have completely different effects on the temperature distribution. Moreover, the heat transfer characteristics in the presence of non-uniform heat flux for several values of physical parameters are also found to be interesting

Observer-based output feedback control of networked control systems with non-uniform sampling and time-varying delay

Science.gov (United States)

Meng, Su; Chen, Jie; Sun, Jian

2017-10-01

This paper investigates the problem of observer-based output feedback control for networked control systems with non-uniform sampling and time-varying transmission delay. The sampling intervals are assumed to vary within a given interval. The transmission delay belongs to a known interval. A discrete-time model is first established, which contains time-varying delay and norm-bounded uncertainties coming from non-uniform sampling intervals. It is then converted to an interconnection of two subsystems in which the forward channel is delay-free. The scaled small gain theorem is used to derive the stability condition for the closed-loop system. Moreover, the observer-based output feedback controller design method is proposed by utilising a modified cone complementary linearisation algorithm. Finally, numerical examples illustrate the validity and superiority of the proposed method.

Effect of non-uniform Hall parameter on the electrode voltage drop in Faraday-type combustion MHD generators

International Nuclear Information System (INIS)

Gupta, G.P.; Rohatgi, V.K.

1982-01-01

Following a simplified approach, an expression is derived for the gas-dynamic voltage drop in a finitely segmented Faraday-type combustion MHD generator, taking into account the non-uniform Hall parameter across the channel. Combining the electrical sheath voltage drop, discussed briefly, with the gas-dynamic voltage drop, the effect of a non-uniform Hall parameter on the electrode voltage drop is studied using the theoretical and experimental input parameters of the Indian MHD channel test. The condition for the validity of the usual assumption of uniform Hall parameter across the channel is pointed out. Analysis of the measured electrode voltage drop predicts the real gas conductivity in the core to be in the range of 60 to 75 per cent of the theoretically calculated core conductivity. (author)

A new correlation of non-uniformly heated round tube burnout data

International Nuclear Information System (INIS)

Kirby, G.J.

1966-07-01

A new correlation of non-uniformly heated round tube burnout data is presented. This fits the available data better than any previously published correlation - the root-mean-square deviation being 5.7% for all data at 1000 p.s.i.a. and the worst fit being to data at 2000 p.s.i.a. where the r.m.s. error is 6.6%. The correlation is used to investigate the effect of flux profile changes and no significant increase in burnout power is obtained by modifying the present chopped cosine distribution. (author)

Non-uniform plastic deformation of micron scale objects

DEFF Research Database (Denmark)

Niordson, Christian Frithiof; Hutchinson, J. W.

2003-01-01

Significant increases in apparent flow strength are observed when non-uniform plastic deformation of metals occurs at the scale ranging from roughly one to ten microns. Several basic plane strain problems are analyzed numerically in this paper based on a new formulation of strain gradient...... plasticity. The problems are the tangential and normal loading of a finite rectangular block of material bonded to rigid platens and having traction-free ends, and the normal loading of a half-space by a flat, rigid punch. The solutions illustrate fundamental features of plasticity at the micron scale...... that are not captured by conventional plasticity theory. These include the role of material length parameters in establishing the size dependence of strength and the elevation of resistance to plastic flow resulting from constraint on plastic flow at boundaries. Details of the finite element method employed...

Two-loop RGE of a general renormalizable Yang-Mills theory in a renormalization scheme with an explicit UV cutoff

Energy Technology Data Exchange (ETDEWEB)

Chankowski, Piotr H. [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw,Pasteura 5, 02-093 Warsaw (Poland); Lewandowski, Adrian [Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut),Mühlenberg 1, D-14476 Potsdam (Germany); Institute of Theoretical Physics, Faculty of Physics, University of Warsaw,Pasteura 5, 02-093 Warsaw (Poland); Meissner, Krzysztof A. [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw,Pasteura 5, 02-093 Warsaw (Poland)

2016-11-18

We perform a systematic one-loop renormalization of a general renormalizable Yang-Mills theory coupled to scalars and fermions using a regularization scheme with a smooth momentum cutoff Λ (implemented through an exponential damping factor). We construct the necessary finite counterterms restoring the BRST invariance of the effective action by analyzing the relevant Slavnov-Taylor identities. We find the relation between the renormalized parameters in our scheme and in the conventional (MS)-bar scheme which allow us to obtain the explicit two-loop renormalization group equations in our scheme from the known two-loop ones in the (MS)-bar scheme. We calculate in our scheme the divergences of two-loop vacuum graphs in the presence of a constant scalar background field which allow us to rederive the two-loop beta functions for parameters of the scalar potential. We also prove that consistent application of the proposed regularization leads to counterterms which, together with the original action, combine to a bare action expressed in terms of bare parameters. This, together with treating Λ as an intrinsic scale of a hypothetical underlying finite theory of all interactions, offers a possibility of an unconventional solution to the hierarchy problem if no intermediate scales between the electroweak scale and the Planck scale exist.

Colour schemes

DEFF Research Database (Denmark)

van Leeuwen, Theo

2013-01-01

This chapter presents a framework for analysing colour schemes based on a parametric approach that includes not only hue, value and saturation, but also purity, transparency, luminosity, luminescence, lustre, modulation and differentiation.......This chapter presents a framework for analysing colour schemes based on a parametric approach that includes not only hue, value and saturation, but also purity, transparency, luminosity, luminescence, lustre, modulation and differentiation....

Image restoration from non-uniform magnetic field influence for direct Fourier NMR imaging

International Nuclear Information System (INIS)

Sekihara, K.; Kuroda, M.; Kohno, H.

1984-01-01

A new technique is proposed for NMR image restoration from the influence of main magnetic field non-uniformities. This technique is applicable to direct Fourier NMR imaging. The mathematical basis and details of this technique are fully described. Modification to include image restoration from non-linear field gradient influence is also presented. Computer simulation demonstrates the effectiveness of this technique for both Fourier zeugmatography and spin-warp imaging. (author)

Decomposed Photo Response Non-Uniformity for Digital Forensic Analysis

Science.gov (United States)

Li, Yue; Li, Chang-Tsun

The last few years have seen the applications of Photo Response Non-Uniformity noise (PRNU) - a unique stochastic fingerprint of image sensors, to various types of digital forensic investigations such as source device identification and integrity verification. In this work we proposed a new way of extracting PRNU noise pattern, called Decomposed PRNU (DPRNU), by exploiting the difference between the physical andartificial color components of the photos taken by digital cameras that use a Color Filter Array for interpolating artificial components from physical ones. Experimental results presented in this work have shown the superiority of the proposed DPRNU to the commonly used version. We also proposed a new performance metrics, Corrected Positive Rate (CPR) to evaluate the performance of the common PRNU and the proposed DPRNU.

An inter-lighting interference cancellation scheme for MISO-VLC systems

Science.gov (United States)

Kim, Kyuntak; Lee, Kyujin; Lee, Kyesan

2017-08-01

In this paper, we propose an inter-lighting interference cancellation (ILIC) scheme to reduce the interference between adjacent light-emitting diodes (LEDs) and enhance the transmission capacity of multiple-input-single-output (MISO)-visible light communication (VLC) systems. In indoor environments, multiple LEDs have normally been used as lighting sources, allowing the design of MISO-VLC systems. To enhance the transmission capacity, different data should be simultaneously transmitted from each LED; however, that can lead to interference between adjacent LEDs. In that case, relatively low-received power signals are subjected to large interference because wireless optical systems generally use intensity modulation and direct detection. Thus, only the signal with the highest received power can be detected, while the other received signals cannot be detected. To solve this problem, we propose the ILIC scheme for MISO-VLC systems. The proposed scheme preferentially detects the highest received power signal, and this signal is referred as interference signal by an interference component generator. Then, relatively low-received power signal can be detected by cancelling the interference signal from the total received signals. Therefore, the performance of the proposed scheme can improve the total average bit error rate and throughput of a MISO-VLC system.

Application of a robust and efficient Lagrangian particle scheme to soot transport in turbulent flames

KAUST Repository

Attili, Antonio

2013-09-01

A Lagrangian particle scheme is applied to the solution of soot dynamics in turbulent nonpremixed flames. Soot particulate is described using a method of moments and the resulting set of continuum advection-reaction equations is solved using the Lagrangian particle scheme. The key property of the approach is the independence between advection, described by the movement of Lagrangian notional particles along pathlines, and internal aerosol processes, evolving on each notional particle via source terms. Consequently, the method overcomes the issues in Eulerian grid-based schemes for the advection of moments: errors in the advective fluxes pollute the moments compromising their realizability and the stiffness of source terms weakens the stability of the method. The proposed scheme exhibits superior properties with respect to conventional Eulerian schemes in terms of stability, accuracy, and grid convergence. Taking into account the quality of the solution, the Lagrangian approach can be computationally more economical than commonly used Eulerian schemes as it allows the resolution requirements dictated by the different physical phenomena to be independently optimized. Finally, the scheme posseses excellent scalability on massively parallel computers. © 2013 Elsevier Ltd.

Stress state of thin – walled member of the structure with operation damages under nonuniform loading

Directory of Open Access Journals (Sweden)

В.В. Астанін

2004-01-01

Full Text Available  The publication is dedicated to determining of stress state in particular the stress concentration factors for thin – walled members of the structures subject to nonuniform tension. A structure member has obtained the operation damage generation by corrosion and other causes.

Anonymous authentication and location privacy preserving schemes for LTE-A networks

Directory of Open Access Journals (Sweden)

Zaher Jabr Haddad

2017-11-01

Full Text Available Long Term Evaluation Advanced (LTE-A is the third generation partnership project for cellular network that allows subscribers to roam into networks (i.e., the Internet and wireless connections using spacial purpose base-stations, such as wireless access points and home node B. In such LTE-A based networks, neither base-stations, nor the Internet and wireless connections are trusted because base-stations are operated by un-trusted subscribers. Attackers may exploit these vulnerabilities to violate the privacy of the LTE-A subscribers. On the other hand, the tradeoff between privacy and authentication is another challenge in such networks. Therefore, in this paper, we propose two anonymous authentication schemes based on one-time pseudonymes and Schnorr Zero Knowledge Protocols. Instead of the international mobile subscriber identity, these schemes enable the user equipment, base-stations and mobility management entity to mutually authenticate each others and update the location of the user equipment without evolving the home subscriber server. The security analysis demonstrate that the proposed schemes thwart security and privacy attacks, such as malicious, international mobile subscriber identity catching, and tracking attacks. Additionally, our proposed schemes preserve the location privacy of user equipment since no entity except the mobility management entity and Gate-Way Mobile Location Center can link between the pseudonymes and the international mobile subscriber identity. Also attackers have no knowledge about international mobile subscriber identity. Hence, the proposed schemes achieve backward/forward secrecy. Furthermore, the performance evaluation shows that the proposed handover schemes impose a small overhead on the mobile nodes and it has smaller computation and communication overheads than those in other schemes.

Splitting Schemes & Segregation In Reaction-(Cross-)Diffusion Systems

OpenAIRE

Carrillo, José A.; Fagioli, Simone; Santambrogio, Filippo; Schmidtchen, Markus

2017-01-01

One of the most fascinating phenomena observed in reaction-diffusion systems is the emergence of segregated solutions, i.e. population densities with disjoint supports. We analyse such a reaction cross-diffusion system. In order to prove existence of weak solutions for a wide class of initial data without restriction about their supports or their positivity, we propose a variational splitting scheme combining ODEs with methods from optimal transport. In addition, this approach allows us to pr...

SDN-Based Mobile Data Offloading Scheme Using a Femtocell and WiFi Networks

Directory of Open Access Journals (Sweden)

Chang-Woo Ahn

2017-01-01

Full Text Available Because of the many applications running on smartphones, the load of mobile data traffic on cellular networks is increasing rapidly. A femtocell is a solution to increase the cellular network capacity and coverage. However, because it uses the same frequency bands as a macrocell, interference problems have prevented its widespread adoption. In this paper, we propose a scheme for traffic offloading between femtocells and WiFi networks utilizing software-defined networking (SDN technology. In the proposed offloading scheme, the SDN technology allows a terminal to maintain existing sessions after offloading through a centralized control of the SDN-based equipment. We also propose an offloading target selection scheme based on available bandwidth estimation and an association control mechanism to reduce the femtocell load while ensuring quality of service (QoS in terms of throughput. Experimental results on an actual testbed showed that the proposed offloading scheme provides seamless connectivity and reduces the femtocell load by up to 46% with the aid of the proposed target selection scheme, while ensuring QoS after offloading. We also observed that the proposed target selection scheme offloads 28% more traffic to WiFi networks compared to received signal strength indicator-based target selection in a low background traffic environment.

Influence of Non-uniform Temperature Field on Spectra of Fibre Bragg Grating

International Nuclear Information System (INIS)

Yan, Zhou; Xing-Fang, He; Xiao-Yong, Fang; Jie, Yuan; Li-Qun, Yin; Mao-Sheng, Cao

2009-01-01

We simulate the spectrum characteristics of fibre Bragg grating (FBG) with non-uniform temperature using the transmission matrix method, and the results are analysed. It is found that firstly the modulated coefficient of average refractive index is a very important parameter that influences the spectrum characteristic of the fibre Bragg grating, and secondly the spectrum curves are different in different temperature fields at the same parameter. Hence, we can determine the metrical temperature by analysing the spectrum of fibre Bragg grating

Nonuniform sampling by quantiles

Science.gov (United States)

Craft, D. Levi; Sonstrom, Reilly E.; Rovnyak, Virginia G.; Rovnyak, David

2018-03-01

A flexible strategy for choosing samples nonuniformly from a Nyquist grid using the concept of statistical quantiles is presented for broad classes of NMR experimentation. Quantile-directed scheduling is intuitive and flexible for any weighting function, promotes reproducibility and seed independence, and is generalizable to multiple dimensions. In brief, weighting functions are divided into regions of equal probability, which define the samples to be acquired. Quantile scheduling therefore achieves close adherence to a probability distribution function, thereby minimizing gaps for any given degree of subsampling of the Nyquist grid. A characteristic of quantile scheduling is that one-dimensional, weighted NUS schedules are deterministic, however higher dimensional schedules are similar within a user-specified jittering parameter. To develop unweighted sampling, we investigated the minimum jitter needed to disrupt subharmonic tracts, and show that this criterion can be met in many cases by jittering within 25-50% of the subharmonic gap. For nD-NUS, three supplemental components to choosing samples by quantiles are proposed in this work: (i) forcing the corner samples to ensure sampling to specified maximum values in indirect evolution times, (ii) providing an option to triangular backfill sampling schedules to promote dense/uniform tracts at the beginning of signal evolution periods, and (iii) providing an option to force the edges of nD-NUS schedules to be identical to the 1D quantiles. Quantile-directed scheduling meets the diverse needs of current NUS experimentation, but can also be used for future NUS implementations such as off-grid NUS and more. A computer program implementing these principles (a.k.a. QSched) in 1D- and 2D-NUS is available under the general public license.

A Time Marching Scheme for Solving Volume Integral Equations on Nonlinear Scatterers

KAUST Repository

Bagci, Hakan

2015-01-07

Transient electromagnetic field interactions on inhomogeneous penetrable scatterers can be analyzed by solving time domain volume integral equations (TDVIEs). TDVIEs are oftentimes solved using marchingon-in-time (MOT) schemes. Unlike finite difference and finite element schemes, MOT-TDVIE solvers require discretization of only the scatterers, do not call for artificial absorbing boundary conditions, and are more robust to numerical phase dispersion. On the other hand, their computational cost is high, they suffer from late-time instabilities, and their implicit nature makes incorporation of nonlinear constitutive relations more difficult. Development of plane-wave time-domain (PWTD) and FFT-based schemes has significantly reduced the computational cost of the MOT-TDVIE solvers. Additionally, latetime instability problem has been alleviated for all practical purposes with the development of accurate integration schemes and specially designed temporal basis functions. Addressing the third challenge is the topic of this presentation. I will talk about an explicit MOT scheme developed for solving the TDVIE on scatterers with nonlinear material properties. The proposed scheme separately discretizes the TDVIE and the nonlinear constitutive relation between electric field intensity and flux density. The unknown field intensity and flux density are expanded using half and full Schaubert-Wilton-Glisson (SWG) basis functions in space and polynomial temporal interpolators in time. The resulting coupled system of the discretized TDVIE and constitutive relation is integrated in time using an explicit P E(CE) m scheme to yield the unknown expansion coefficients. Explicitness of time marching allows for straightforward incorporation of the nonlinearity as a function evaluation on the right hand side of the coupled system of equations. Consequently, the resulting MOT scheme does not call for a Newton-like nonlinear solver. Numerical examples, which demonstrate the applicability

A Time Marching Scheme for Solving Volume Integral Equations on Nonlinear Scatterers

KAUST Repository

Bagci, Hakan

2015-01-01

Transient electromagnetic field interactions on inhomogeneous penetrable scatterers can be analyzed by solving time domain volume integral equations (TDVIEs). TDVIEs are oftentimes solved using marchingon-in-time (MOT) schemes. Unlike finite difference and finite element schemes, MOT-TDVIE solvers require discretization of only the scatterers, do not call for artificial absorbing boundary conditions, and are more robust to numerical phase dispersion. On the other hand, their computational cost is high, they suffer from late-time instabilities, and their implicit nature makes incorporation of nonlinear constitutive relations more difficult. Development of plane-wave time-domain (PWTD) and FFT-based schemes has significantly reduced the computational cost of the MOT-TDVIE solvers. Additionally, latetime instability problem has been alleviated for all practical purposes with the development of accurate integration schemes and specially designed temporal basis functions. Addressing the third challenge is the topic of this presentation. I will talk about an explicit MOT scheme developed for solving the TDVIE on scatterers with nonlinear material properties. The proposed scheme separately discretizes the TDVIE and the nonlinear constitutive relation between electric field intensity and flux density. The unknown field intensity and flux density are expanded using half and full Schaubert-Wilton-Glisson (SWG) basis functions in space and polynomial temporal interpolators in time. The resulting coupled system of the discretized TDVIE and constitutive relation is integrated in time using an explicit P E(CE) m scheme to yield the unknown expansion coefficients. Explicitness of time marching allows for straightforward incorporation of the nonlinearity as a function evaluation on the right hand side of the coupled system of equations. Consequently, the resulting MOT scheme does not call for a Newton-like nonlinear solver. Numerical examples, which demonstrate the applicability

Experimental results on advanced inertial fusion schemes obtained within the HiPER project

International Nuclear Information System (INIS)

Batani, Dimitri; Santos, Jorge J.; Schurtz, Guy; Hulin, Sebastien; Ribeyre, Xavier; Nicolai, Philippe; Vauzour, Benjamin; Dorchies, Fabien; Gizzi, Leonida A.; Koester, Petra; Labate, Luca; Honrubia, Javier; Antonelli, Luca; Morace, Alessio; Volpe, Luca; Nazarov, Wiger; Pasley, John; Richetta, Maria; Lancaster, Kate; Spindloe, Christopher; Tolley, Martin; Neely, David; Kozlova, Michaela; Nejdl, Jaroslav; Rus, Bedrich; Wolowski, Jerzy; Badziak, Jan

2012-01-01

This paper presents the results of experiments conducted within the Work Package 10 (fusion experimental programme) of the HiPER project. The aim of these experiments was to study the physics relevant for advanced ignition schemes for inertial confinement fusion, i.e. the fast ignition and the shock ignition. Such schemes allow to achieve a higher fusion gain compared to the indirect drive approach adopted in the National Ignition Facility in United States, which is important for the future inertial fusion energy reactors and for realising the inertial fusion with smaller facilities. (authors)

Non-uniform temperature field measurement and simulation of a radio telescope’s main reflector under solar radiation

International Nuclear Information System (INIS)

Chen, Deshen; Qian, Hongliang; Wang, Huajie; Zhang, Gang; Fan, Feng; Shen, Shizhao

2017-01-01

Highlights: • Solar non-uniform temperature field test of a telescope’s reflector is conducted initially. • Time-varying distribution regularities are analyzed contrastively. • Simulation methods are proposed involving environmental factors and self-shadowing. • Refined discrimination method for the shadow distribution is put forward. • Validity of simulation methods is evaluated with the experimental data. - Abstract: To improve the ability of deep-space exploration, many astronomers around the world are actively engaged in the construction of large-aperture and high-precision radio telescopes. The temperature effect is one of three main factors affecting the reflector accuracy of radio telescopes. To study the daily non-uniform temperature field of the main reflector, experimental studies are first carried out with a 3-m-aperture radio telescope model. According to the test results for 16 working conditions, the distribution rule and time-varying regularity of the daily temperature field are summarized initially. Next, theoretical methods for the temperature field of the main reflector are studied considering multiple environmental parameters and self-shadows. Finally, the validity of the theoretical methods is evaluated with test results. The experimental study demonstrates that the non-uniform temperature distribution of the main reflector truly exists and should not be overlooked, and that the theoretical methods for the reflector temperature field proposed in this paper are effective. The research methods and conclusions can provide valuable references for thermal design, monitoring and control of similar high-precision radio telescopes.

A continuous latitudinal energy balance model to explore non-uniform climate engineering strategies

Science.gov (United States)

Bonetti, F.; McInnes, C. R.

2016-12-01

Current concentrations of atmospheric CO2 exceed measured historical levels in modern times, largely attributed to anthropogenic forcing since the industrial revolution. The required decline in emissions rates has never been achieved leading to recent interest in climate engineering for future risk-mitigation strategies. Climate engineering aims to offset human-driven climate change. It involves techniques developed both to reduce the concentration of CO2 in the atmosphere (Carbon Dioxide Removal (CDR) methods) and to counteract the radiative forcing that it generates (Solar Radiation Management (SRM) methods). In order to investigate effects of SRM technologies for climate engineering, an analytical model describing the main dynamics of the Earth's climate has been developed. The model is a time-dependent Energy Balance Model (EBM) with latitudinal resolution and allows for the evaluation of non-uniform climate engineering strategies. A significant disadvantage of climate engineering techniques involving the management of solar radiation is regional disparities in cooling. This model offers an analytical approach to design multi-objective strategies that counteract climate change on a regional basis: for example, to cool the Artic and restrict undesired impacts at mid-latitudes, or to control the equator-to-pole temperature gradient. Using the Green's function approach the resulting partial differential equation allows for the computation of the surface temperature as a function of time and latitude when a 1% per year increase in the CO2 concentration is considered. After the validation of the model through comparisons with high fidelity numerical models, it will be used to explore strategies for the injection of the aerosol precursors in the stratosphere. In particular, the model involves detailed description of the optical properties of the particles, the wash-out dynamics and the estimation of the radiative cooling they can generate.

The influence of nonuniform micro-distribution of alpha emitter on microdosimetry in cells

International Nuclear Information System (INIS)

Tian Yuan; Zhang Liang'an; Dai Guangfu

2007-01-01

Objective: To study the influence of nonuniform micro-distribution of alpha emitter on cellular S values(in the radioimmunotherapy). Methods: Emission of alpha particles is randomly simulated by Monte Carlo method; the incident energy and exit energy are calculated with interpolation technique based on the relationship between range and energy of alpha particle and the analytical Continuous Slowing Down Approximation (CSDA) model. So energy deposited in the target area can be obtained. To take 213 Po as an example, cellular S values with various cell dimensions and possible micro-distributions of radioactivity are calculated, such as linear increase, linear decrease, exponential increase and exponential decrease. Results: S values from cell to cell of uniform distribution showed no difference with the Hamacher's results. S values of different micro-distributions are distinguishing with each other. It is indicated that different micro-distributions of radioactivity will result in significant change of average chord length of alpha particles traveling in the target area, as well as the change of average stopping power over the chord, which is primary reason for differences of S values. Conclusions: The nonuniform micro-distributions show remarkable influence on cellular S values and hence should be taken consideration in cellular absorbed dose estimation, especially in microdosimetry. (authors)

REMINDER - Extension/suppression of allowance for dependent children aged 20 to 25

CERN Multimedia

HR Department

2008-01-01

Members of the personnel with dependent children aged 20 to 25 (or reaching 20 during the 2008/2009 school year), for whom an allowance for dependent children is paid, must provide the School Fees service with a: SCHOOL CERTIFICATE Unless we receive, by 31 October, 2008 at the latest, a school certificate or similar written proof (contract of work placement, sandwich course or apprenticeship) covering your child / children for the school year 2008/2009, we will be obliged to stop payment of the allowance for dependent children as well as affiliation to the health insurance scheme retroactively as of1st July 2008. School fees service (33-1-017) HR/SPS-SER Tel. 72862

REMINDER - Extension/suppression of allowance for dependent children aged 20 to 25

CERN Multimedia

HR Department

2010-01-01

Members of the personnel with dependent children aged 20 to 25 (or reaching 20 during the 2010/2011 school year), for whom an allowance for dependent children is currently paid, are invited to provide the Education Fees Service with a: SCHOOL CERTIFICATE Unless we receive, by 31 October 2010 at the latest, a school certificate or similar written proof (work placement contract, evidence of sandwich courses or apprenticeship) covering your child / children for the school year 2010/2011, we will be obliged to stop payment of the allowance for dependent children as well as membership of the health insurance scheme at the appropriate date, retroactively if necessary. Education Fees Service HR/SPS-SER Tel. 72862 / 71421

Reminder - Extension/suppression of allowance for dependent children aged 20 to 25

CERN Multimedia

HR Department

2009-01-01

Members of the personnel with dependent children aged 20 to 25 (or reaching 20 during the 2009/2010 school year), for whom a dependent child’s allowance is currently paid, are invited to provide the Education Fees service with a: SCHOOL CERTIFICATE Unless we receive, by October 31, 2009 at the latest, a school certificate or similar written proof (contract of work placement, sandwich course or apprenticeship) covering your child / children for the 2009/2010 school year, we will be obliged to stop payment of the dependent child’s allowance as well as membership of the health insurance scheme at the appropriate date, retroactively if necessary. Education Fees service (33-1-017) HR Department - Tel. 72862

Correction method and software for image distortion and nonuniform response in charge-coupled device-based x-ray detectors utilizing x-ray image intensifier

International Nuclear Information System (INIS)

Ito, Kazuki; Kamikubo, Hironari; Yagi, Naoto; Amemiya, Yoshiyuki

2005-01-01

An on-site method of correcting the image distortion and nonuniform response of a charge-coupled device (CCD)-based X-ray detector was developed using the response of the imaging plate as a reference. The CCD-based X-ray detector consists of a beryllium-windowed X-ray image intensifier (Be-XRII) and a CCD as the image sensor. An image distortion of 29% was improved to less than 1% after the correction. In the correction of nonuniform response due to image distortion, subpixel approximation was performed for the redistribution of pixel values. The optimal number of subpixels was also discussed. In an experiment with polystyrene (PS) latex, it was verified that the correction of both image distortion and nonuniform response worked properly. The correction for the 'contrast reduction' problem was also demonstrated for an isotropic X-ray scattering pattern from the PS latex. (author)

Nonuniform multiview color texture mapping of image sequence and three-dimensional model for faded cultural relics with sift feature points

Science.gov (United States)

Li, Na; Gong, Xingyu; Li, Hongan; Jia, Pengtao

2018-01-01

For faded relics, such as Terracotta Army, the 2D-3D registration between an optical camera and point cloud model is an important part for color texture reconstruction and further applications. This paper proposes a nonuniform multiview color texture mapping for the image sequence and the three-dimensional (3D) model of point cloud collected by Handyscan3D. We first introduce nonuniform multiview calibration, including the explanation of its algorithm principle and the analysis of its advantages. We then establish transformation equations based on sift feature points for the multiview image sequence. At the same time, the selection of nonuniform multiview sift feature points is introduced in detail. Finally, the solving process of the collinear equations based on multiview perspective projection is given with three steps and the flowchart. In the experiment, this method is applied to the color reconstruction of the kneeling figurine, Tangsancai lady, and general figurine. These results demonstrate that the proposed method provides an effective support for the color reconstruction of the faded cultural relics and be able to improve the accuracy of 2D-3D registration between the image sequence and the point cloud model.