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Sample records for generates realistic connection

  1. Simple and Realistic Data Generation

    DEFF Research Database (Denmark)

    Pedersen, Kenneth Houkjær; Torp, Kristian; Wind, Rico

    2006-01-01

    This paper presents a generic, DBMS independent, and highly extensible relational data generation tool. The tool can efficiently generate realistic test data for OLTP, OLAP, and data streaming applications. The tool uses a graph model to direct the data generation. This model makes it very simple...

  2. Generating realistic roofs over a rectilinear polygon

    KAUST Repository

    Ahn, Heekap

    2011-01-01

    Given a simple rectilinear polygon P in the xy-plane, a roof over P is a terrain over P whose faces are supported by planes through edges of P that make a dihedral angle π/4 with the xy-plane. In this paper, we introduce realistic roofs by imposing a few additional constraints. We investigate the geometric and combinatorial properties of realistic roofs, and show a connection with the straight skeleton of P. We show that the maximum possible number of distinct realistic roofs over P is ( ⌊(n-4)/4⌋ (n-4)/2) when P has n vertices. We present an algorithm that enumerates a combinatorial representation of each such roof in O(1) time per roof without repetition, after O(n 4) preprocessing time. We also present an O(n 5)-time algorithm for computing a realistic roof with minimum height or volume. © 2011 Springer-Verlag.

  3. Generating Realistic Environments for Cyber Operations Development, Testing, and Training

    Science.gov (United States)

    2011-10-01

    capture comparator ................................................................. 11  Figure 9. Detailed view of social net behavioral analysis scoring...of social net behavioral analysis scoring 5.0 CONCLUSIONS AND RECOMMENDATIONS Truly realistic traffic generation can arguably only be achieved

  4. Generating Realistic Labelled, Weighted Random Graphs

    CERN Document Server

    Davis, Michael Charles; Liu, Weiru; Miller, Paul; Hunter, Ruth; Kee, Frank

    2015-01-01

    Generative algorithms for random graphs have yielded insights into the structure and evolution of real-world networks. Most networks exhibit a well-known set of properties, such as heavy-tailed degree distributions, clustering and community formation. Usually, random graph models consider only structural information, but many real-world networks also have labelled vertices and weighted edges. In this paper, we present a generative model for random graphs with discrete vertex labels and numeric edge weights. The weights are represented as a set of Beta Mixture Models (BMMs) with an arbitrary number of mixtures, which are learned from real-world networks. We propose a Bayesian Variational Inference (VI) approach, which yields an accurate estimation while keeping computation times tractable. We compare our approach to state-of-the-art random labelled graph generators and an earlier approach based on Gaussian Mixture Models (GMMs). Our results allow us to draw conclusions about the contribution of vertex labels a...

  5. A method for generating realistic correlation matrices

    CERN Document Server

    Garcia, Stephan Ramon

    2011-01-01

    Simulating sample correlation matrices is important in many areas of statistics. Approaches such as generating normal data and finding their sample correlation matrix or generating random uniform $[-1,1]$ deviates as pairwise correlations both have drawbacks. We develop an algorithm for adding noise, in a highly controlled manner, to general correlation matrices. In many instances, our method yields results which are superior to those obtained by simply simulating normal data. Moreover, we demonstrate how our general algorithm can be tailored to a number of different correlation models. Finally, using our results with an existing clustering algorithm, we show that simulating correlation matrices can help assess statistical methodology.

  6. Generating Realistic Labelled, Weighted Random Graphs

    Directory of Open Access Journals (Sweden)

    Michael Charles Davis

    2015-12-01

    Full Text Available Generative algorithms for random graphs have yielded insights into the structure and evolution of real-world networks. Most networks exhibit a well-known set of properties, such as heavy-tailed degree distributions, clustering and community formation. Usually, random graph models consider only structural information, but many real-world networks also have labelled vertices and weighted edges. In this paper, we present a generative model for random graphs with discrete vertex labels and numeric edge weights. The weights are represented as a set of Beta Mixture Models (BMMs with an arbitrary number of mixtures, which are learned from real-world networks. We propose a Bayesian Variational Inference (VI approach, which yields an accurate estimation while keeping computation times tractable. We compare our approach to state-of-the-art random labelled graph generators and an earlier approach based on Gaussian Mixture Models (GMMs. Our results allow us to draw conclusions about the contribution of vertex labels and edge weights to graph structure.

  7. The Always-Connected Generation

    Science.gov (United States)

    Bull, Glen

    2010-01-01

    The Pew Internet and American Life project characterizes the millennials--the first generation to come of age in the new millennium--as the first "always-connected" generation. Significant aspects of culture are changing as a result. A changing world where all students are connected all the time has substantial educational implications. Despite…

  8. Survey of Approaches to Generate Realistic Synthetic Graphs

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Seung-Hwan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lee, Sangkeun [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Powers, Sarah S [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Shankar, Mallikarjun [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Imam, Neena [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-10-01

    A graph is a flexible data structure that can represent relationships between entities. As with other data analysis tasks, the use of realistic graphs is critical to obtaining valid research results. Unfortunately, using the actual ("real-world") graphs for research and new algorithm development is difficult due to the presence of sensitive information in the data or due to the scale of data. This results in practitioners developing algorithms and systems that employ synthetic graphs instead of real-world graphs. Generating realistic synthetic graphs that provide reliable statistical confidence to algorithmic analysis and system evaluation involves addressing technical hurdles in a broad set of areas. This report surveys the state of the art in approaches to generate realistic graphs that are derived from fitted graph models on real-world graphs.

  9. Configuration of Dual Connectivity with Flow Control in a Realistic Urban Scenario

    DEFF Research Database (Denmark)

    Wang, Hua; Gerardino, Guillermo Andrés Pocovi; Rosa, Claudio;

    2015-01-01

    the performance of DC in a realistic deployment based on three-dimensional data from a dense urban European capital area, assuming realistic flow control on the backhaul connections between the macro and small cell eNBs. It is found that the configuration of UEs with DC plays a critical role in the performance...

  10. An iterative approach for generating statistically realistic populations of households

    CERN Document Server

    Gargiulo, Floriana; Huet, Sylvie; Deffuant, Guillaume

    2009-01-01

    Background: Many different simulation frameworks, in different topics, need to treat realistic datasets to initialize and calibrate the system. A precise reproduction of initial states is extremely important to obtain reliable forecast from the model. Methodology/Principal Findings: This paper proposes an algorithm to create an artificial population where individuals are described by their age, and are gathered in households respecting a variety of statistical constraints (distribution of household types, sizes, age of household head, difference of age between partners and among parents and children). Such a population is often the initial state of microsimulation or (agent) individual-based models. To get a realistic distribution of households is often very important, because this distribution has an impact on the demographic evolution. Usual techniques from microsimulation approach cross different sources of aggregated data for generating individuals. In our case the number of combinations of different hous...

  11. Realistic facial animation generation based on facial expression mapping

    Science.gov (United States)

    Yu, Hui; Garrod, Oliver; Jack, Rachael; Schyns, Philippe

    2014-01-01

    Facial expressions reflect internal emotional states of a character or in response to social communications. Though much effort has been taken to generate realistic facial expressions, it still remains a challenging topic due to human being's sensitivity to subtle facial movements. In this paper, we present a method for facial animation generation, which reflects true facial muscle movements with high fidelity. An intermediate model space is introduced to transfer captured static AU peak frames based on FACS to the conformed target face. And then dynamic parameters derived using a psychophysics method is integrated to generate facial animation, which is assumed to represent natural correlation of multiple AUs. Finally, the animation sequence in the intermediate model space is mapped to the target face to produce final animation.

  12. Generation of anatomically realistic numerical phantoms for optoacoustic breast imaging

    Science.gov (United States)

    Lou, Yang; Mitsuhashi, Kenji; Appleton, Catherine M.; Oraevsky, Alexander; Anastasio, Mark A.

    2016-03-01

    Because optoacoustic tomography (OAT) can provide functional information based on hemoglobin contrast, it is a promising imaging modality for breast cancer diagnosis. Developing an effective OAT breast imaging system requires balancing multiple design constraints, which can be expensive and time-consuming. Therefore, computer- simulation studies are often conducted to facilitate this task. However, most existing computer-simulation studies of OAT breast imaging employ simple phantoms such as spheres or cylinders that over-simplify the complex anatomical structures in breasts, thus limiting the value of these studies in guiding real-world system design. In this work, we propose a method to generate realistic numerical breast phantoms for OAT research based on clinical magnetic resonance imaging (MRI) data. The phantoms include a skin layer that defines breast-air boundary, major vessel branches that affect light absorption in the breast, and fatty tissue and fibroglandular tissue whose acoustical heterogeneity perturbs acoustic wave propagation. By assigning realistic optical and acoustic parameters to different tissue types, we establish both optic and acoustic breast phantoms, which will be exported into standard data formats for cross-platform usage.

  13. Tool for Generating Realistic Residential Hot Water Event Schedules: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Hendron, B.; Burch, J.; Barker, G.

    2010-08-01

    The installed energy savings for advanced residential hot water systems can depend greatly on detailed occupant use patterns. Quantifying these patterns is essential for analyzing measures such as tankless water heaters, solar hot water systems with demand-side heat exchangers, distribution system improvements, and recirculation loops. This paper describes the development of an advanced spreadsheet tool that can generate a series of year-long hot water event schedules consistent with realistic probability distributions of start time, duration and flow rate variability, clustering, fixture assignment, vacation periods, and seasonality. This paper also presents the application of the hot water event schedules in the context of an integral-collector-storage solar water heating system in a moderate climate.

  14. Realistic packed bed generation using small numbers of spheres

    Energy Technology Data Exchange (ETDEWEB)

    Pavlidis, D., E-mail: dimitrios.pavlidis04@imperial.ac.uk; Lathouwers, D.

    2013-10-15

    Highlights: • A method for generating 3D, periodic, closely packed beds of small numbers (<50) of spheres is presented. • The method is able to reproduce characteristics for the entirety (including nearwall area) of a randomly stacked bed. • Results are in good agreement with reference numerical data. -- Abstract: A method for stochastically generating three-dimensional, periodic, closely packed beds of small numbers (less than 50) of spheres is presented. This is an essential and integral part of realistic modelling of fluid flow and heat transfer through packed beds. In order to be able to reproduce the entirety of these complex geometries (in the radial direction) using small numbers of spheres, they are divided into two regions: the near-wall region (up to 4–5 sphere diameters from the solid wall in the wall-normal direction) and the core region. Near-wall stackings are doubly periodic and include a solid wall, while core stackings are triply periodic. A computational method for generating such geometries is presented for each region. Both are based on overlap removal methods. Results are compared against reference numerical data. Diagnostics used to evaluate the models include average packing fractions and coordination numbers, porosity profiles and distributions of the angle between two spheres which touch a common neighbour. Results are in good qualitative and quantitative agreement with the available reference data.

  15. Optimizing Wind And Hydropower Generation Within Realistic Reservoir Operating Policy

    Science.gov (United States)

    Magee, T. M.; Clement, M. A.; Zagona, E. A.

    2012-12-01

    Previous studies have evaluated the benefits of utilizing the flexibility of hydropower systems to balance the variability and uncertainty of wind generation. However, previous hydropower and wind coordination studies have simplified non-power constraints on reservoir systems. For example, some studies have only included hydropower constraints on minimum and maximum storage volumes and minimum and maximum plant discharges. The methodology presented here utilizes the pre-emptive linear goal programming optimization solver in RiverWare to model hydropower operations with a set of prioritized policy constraints and objectives based on realistic policies that govern the operation of actual hydropower systems, including licensing constraints, environmental constraints, water management and power objectives. This approach accounts for the fact that not all policy constraints are of equal importance. For example target environmental flow levels may not be satisfied if it would require violating license minimum or maximum storages (pool elevations), but environmental flow constraints will be satisfied before optimizing power generation. Additionally, this work not only models the economic value of energy from the combined hydropower and wind system, it also captures the economic value of ancillary services provided by the hydropower resources. It is recognized that the increased variability and uncertainty inherent with increased wind penetration levels requires an increase in ancillary services. In regions with liberalized markets for ancillary services, a significant portion of hydropower revenue can result from providing ancillary services. Thus, ancillary services should be accounted for when determining the total value of a hydropower system integrated with wind generation. This research shows that the end value of integrated hydropower and wind generation is dependent on a number of factors that can vary by location. Wind factors include wind penetration level

  16. Towards a realistic event generator for in-medium signals

    Energy Technology Data Exchange (ETDEWEB)

    Seck, Florian [TU Darmstadt (Germany); Collaboration: HADES-Collaboration

    2015-07-01

    The most important task of theoretical heavy-ion physics is to link experimental observables to the bulk properties and the microscopic structure of the different phases of strongly interacting matter. Until now the hadronic cocktails produced with the event generator Pluto for the HADES and CBM experiments only included a contribution from freeze-out ρ mesons modeled by a Breit-Wigner distribution around its pole mass. However as dileptons are radiated from the fireball during the whole time evolution, medium effects like the broadening of the ρ should also be included in the simulations. Calculations of the in-medium ρ spectral function by R. Rapp and J. Wambach demonstrate, that a large part of the in-medium ρ mesons feed into the mass region below the ρ/ω pole mass down to zero masses. The modular structure of Pluto makes it feasible to customize the event generator and incorporate models of in-medium physics, like the Rapp-Wambach spectral function, as plug-ins. For masses above 1 GeV/c{sup 2} we include emission due to multi-pion annihilation and due to QGP radiation. In this contribution first steps towards the implementation of such a plug-in into the event generator Pluto are presented.

  17. A Simplified Model for Generating 3D Realistic Sound in the Multimedia and Virtual Reality Systems

    Institute of Scientific and Technical Information of China (English)

    赵Yu; 何志均; 等

    1996-01-01

    It is a key feature to embed 3D realistic sound effect in the future multimedia and virtual reality systems.Recent research on acoustics and psychoacoustics reveals the important cues for sound localization and sound perception.One promising approach to generate 3D realistic sound effect uses two earphones by simulating the sound waveforms from sound source to eardrum.This paper summarizes two methods for generating 3D realistic sound and points out their inherent drawbacks.To overcome these drawbacks we propose a simplified model to generate 3D realistic sound at any positions in the horizontal plane based on the results of sound perception and localization.Experimental results show that the model is correct and efficient.

  18. Optimal working conditions for thermoelectric generators with realistic thermal coupling

    CERN Document Server

    Apertet, Y; Glavatskaya, O; Goupil, C; Lecoeur, P

    2011-01-01

    We study how maximum output power can be obtained from a thermoelectric generator(TEG) with nonideal heat exchangers. We demonstrate with an analytic approach based on a force-flux formalism that the sole improvement of the intrinsic characteristics of thermoelectric modules including the enhancement of the figure of merit is of limited interest: the constraints imposed by the working conditions of the TEG must be considered on the same footing. Introducing an effective thermal conductance we derive the conditions which permit maximization of both efficiency and power production of the TEG dissipatively coupled to heat reservoirs. Thermal impedance matching must be accounted for as well as electrical impedance matching in order to maximize the output power. Our calculations also show that the thermal impedance does not only depend on the thermal conductivity at zero electrical current: it also depends on the TEG figure of merit. Our analysis thus yields both electrical and thermal conditions permitting optima...

  19. Internet services for planning distributed generation connections

    Energy Technology Data Exchange (ETDEWEB)

    Curry, D.; Morgan, A.; Barbier, C.; Reay, P.

    2005-07-01

    The required publication by distributed network operators (DNOs) of details of the current state of their network systems and future planned developments in the form of Long Term Development Statements (LTDS) are discussed. This project aims to increase the usefulness of the information in the LTDS by making it available on the internet and by providing an initial assessment of connection opportunities and the possibility of viewing existing renewable generation projects. The services developed covered data loading, data visualisation, security, connection assessment, reporting, and generation site registration. The benefits of an electronic version of the LTDS are highlighted.

  20. Hair Image Generation Using Connected Texels

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiaopeng; CHEN Yanyun; WU Enhua

    2001-01-01

    Generation of photo-realistic images of human hair is a challenging topic in computer graphics. The difficulty in solving the problem in this aspect comes mainly from the extremely large number of hairs and the high complexity of the hair shapes. Regarding to the modeling and rendering of hair-type objects,Kajiya proposed a so-called texel model for producing furry surfaces. However,Kajiya's model could be only used for the generation of short hairs. In this paper,a concise and practical approach is presented to solve the problem of rendering long hairs, and in particular the method of rendering the smooth segmental texels for the generation of long hairs is addressed.

  1. NETMORPH: a framework for the stochastic generation of large scale neuronal networks with realistic neuron morphologies

    NARCIS (Netherlands)

    Koene, R.A.; Tijms, B.; van Hees, P.; Postma, F.; de Ridder, A.; Ramakers, G.J.A.; van Pelt, J.; van Ooyen, A.

    2009-01-01

    We present a simulation framework, called NETMORPH, for the developmental generation of 3D large-scale neuronal networks with realistic neuron morphologies. In NETMORPH, neuronal morphogenesis is simulated from the perspective of the individual growth cone. For each growth cone in a growing axonal o

  2. A realistic neural mass model of the cortex with laminar-specific connections and synaptic plasticity - evaluation with auditory habituation.

    Directory of Open Access Journals (Sweden)

    Peng Wang

    Full Text Available In this work we propose a biologically realistic local cortical circuit model (LCCM, based on neural masses, that incorporates important aspects of the functional organization of the brain that have not been covered by previous models: (1 activity dependent plasticity of excitatory synaptic couplings via depleting and recycling of neurotransmitters and (2 realistic inter-laminar dynamics via laminar-specific distribution of and connections between neural populations. The potential of the LCCM was demonstrated by accounting for the process of auditory habituation. The model parameters were specified using Bayesian inference. It was found that: (1 besides the major serial excitatory information pathway (layer 4 to layer 2/3 to layer 5/6, there exists a parallel "short-cut" pathway (layer 4 to layer 5/6, (2 the excitatory signal flow from the pyramidal cells to the inhibitory interneurons seems to be more intra-laminar while, in contrast, the inhibitory signal flow from inhibitory interneurons to the pyramidal cells seems to be both intra- and inter-laminar, and (3 the habituation rates of the connections are unsymmetrical: forward connections (from layer 4 to layer 2/3 are more strongly habituated than backward connections (from Layer 5/6 to layer 4. Our evaluation demonstrates that the novel features of the LCCM are of crucial importance for mechanistic explanations of brain function. The incorporation of these features into a mass model makes them applicable to modeling based on macroscopic data (like EEG or MEG, which are usually available in human experiments. Our LCCM is therefore a valuable building block for future realistic models of human cognitive function.

  3. Complete methodology on generating realistic wind speed profiles based on measurements

    DEFF Research Database (Denmark)

    Gavriluta, Catalin; Spataru, Sergiu; Mosincat, Ioan;

    2012-01-01

    , wind modelling for medium and large time scales is poorly treated in the present literature. This paper presents methods for generating realistic wind speed profiles based on real measurements. The wind speed profile is divided in a low- frequency component (describing long term variations......The wind speed represents the main exogenous signal applied to a Wind Energy Conversion System (WECS) and determines its behavior. The erratic variation of the wind speed, highly dependent on the given site and on the atmospheric conditions, makes the wind speed quite difficult to model. Moreover...

  4. The Teacher's Role in Supporting Students' Connections between Realistic Situations and Conventional Symbol Systems.

    Science.gov (United States)

    Lobato, Joanne; Ellis, Amy Burns

    2002-01-01

    Uses the notion of focusing phenomena to explain how a teacher's actions were connected to her students' interpretations of a linear equation. Conducts interviews and analyzes a high-school classroom that emphasized dependency relationships in real-world situations. Describes how the teacher directed attention away from functional relationships…

  5. Optimized Load Shedding Approach for Grid-Connected DC Microgrid Systems under Realistic Constraints

    Directory of Open Access Journals (Sweden)

    Leonardo Trigueiro dos Santos

    2016-12-01

    Full Text Available The microgrid system is an answer to the necessity of increasing renewable energy penetration and also works as a bridge for the future smart grid. Considering the microgrid system applied to commercial building equipped with photovoltaic sources, the usage of a DC microgrid architecture can improve the efficiency of the system, while ensuring robustness and reducing the overall energy cost. Given the power grid stress and the intermittency of the DC microgrid power production, backup power provision and load shedding operations may occur to stabilize the DC bus voltage. Based on the knapsack problem formulation, this paper presents a realistic optimization approach to shedding a building’s appliances, considering the priority of each appliance, and also considering a minimum amount of load that must be attended. The problem is solved by mixed integer linear programming and the CPLEX solver. The proposed architecture ensures critical load supply and voltage stabilization through the real-time operation of the operational algorithm allowing the load shedding optimization approach to be applied without compromising the robustness of the system. The results obtained by simulation prove that the DC microgrid is able to supply the building power network by applying the load shedding optimization program to overcome, mainly, the renewable energy intermittency.

  6. Generation of anatomically realistic numerical phantoms for photoacoustic and ultrasonic breast imaging.

    Science.gov (United States)

    Lou, Yang; Zhou, Weimin; Matthews, Thomas P; Appleton, Catherine M; Anastasio, Mark A

    2017-04-01

    Photoacoustic computed tomography (PACT) and ultrasound computed tomography (USCT) are emerging modalities for breast imaging. As in all emerging imaging technologies, computer-simulation studies play a critically important role in developing and optimizing the designs of hardware and image reconstruction methods for PACT and USCT. Using computer-simulations, the parameters of an imaging system can be systematically and comprehensively explored in a way that is generally not possible through experimentation. When conducting such studies, numerical phantoms are employed to represent the physical properties of the patient or object to-be-imaged that influence the measured image data. It is highly desirable to utilize numerical phantoms that are realistic, especially when task-based measures of image quality are to be utilized to guide system design. However, most reported computer-simulation studies of PACT and USCT breast imaging employ simple numerical phantoms that oversimplify the complex anatomical structures in the human female breast. We develop and implement a methodology for generating anatomically realistic numerical breast phantoms from clinical contrast-enhanced magnetic resonance imaging data. The phantoms will depict vascular structures and the volumetric distribution of different tissue types in the breast. By assigning optical and acoustic parameters to different tissue structures, both optical and acoustic breast phantoms will be established for use in PACT and USCT studies.

  7. Generation of anatomically realistic numerical phantoms for photoacoustic and ultrasonic breast imaging

    Science.gov (United States)

    Lou, Yang; Zhou, Weimin; Matthews, Thomas P.; Appleton, Catherine M.; Anastasio, Mark A.

    2017-04-01

    Photoacoustic computed tomography (PACT) and ultrasound computed tomography (USCT) are emerging modalities for breast imaging. As in all emerging imaging technologies, computer-simulation studies play a critically important role in developing and optimizing the designs of hardware and image reconstruction methods for PACT and USCT. Using computer-simulations, the parameters of an imaging system can be systematically and comprehensively explored in a way that is generally not possible through experimentation. When conducting such studies, numerical phantoms are employed to represent the physical properties of the patient or object to-be-imaged that influence the measured image data. It is highly desirable to utilize numerical phantoms that are realistic, especially when task-based measures of image quality are to be utilized to guide system design. However, most reported computer-simulation studies of PACT and USCT breast imaging employ simple numerical phantoms that oversimplify the complex anatomical structures in the human female breast. We develop and implement a methodology for generating anatomically realistic numerical breast phantoms from clinical contrast-enhanced magnetic resonance imaging data. The phantoms will depict vascular structures and the volumetric distribution of different tissue types in the breast. By assigning optical and acoustic parameters to different tissue structures, both optical and acoustic breast phantoms will be established for use in PACT and USCT studies.

  8. TextGen:a realistic text data content generation method for modern storage system benchmarks

    Institute of Scientific and Technical Information of China (English)

    Long-xiang WANG; Xiao-she DONG; Xing-jun ZHANG; Yin-feng WANG; Tao JU; Guo-fu FENG

    2016-01-01

    Modern storage systems incorporate data compressors to improve their performance and capacity. As a result, data content can significantly influence the result of a storage system benchmark. Because real-world proprietary datasets are too large to be copied onto a test storage system, and most data cannot be shared due to privacy issues, a benchmark needs to generate data synthetically. To ensure that the result is accurate, it is necessary to generate data content based on the characterization of real-world data properties that influence the storage system performance during the execution of a benchmark. The existing approach, called SDGen, cannot guarantee that the benchmark result is accurate in storage systems that have built-in word-based compressors. The reason is that SDGen characterizes the properties that influence compression performance only at the byte level, and no properties are characterized at the word level. To address this problem, we present TextGen, a realistic text data content generation method for modern storage system benchmarks. TextGen builds the word corpus by segmenting real-world text datasets, and creates a word-frequency distribution by counting each word in the corpus. To improve data generation performance, the word-frequency distribution is fitted to a lognormal distribution by maximum likelihood estimation. The Monte Carlo approach is used to generate synthetic data. The running time of TextGen generation depends only on the expected data size, which means that the time complexity of TextGen isO(n). To evaluate TextGen, four real-world datasets were used to perform an experiment. The experimental results show that, compared with SDGen, the compression performance and compression ratio of the datasets generated by TextGen deviate less from real-world datasets when end-tagged dense code, a representative of word-based compressors, is evaluated.

  9. The 4-D descent trajectory generation techniques under realistic operating conditions

    Science.gov (United States)

    Williams, David H.; Knox, Charles E.

    1990-01-01

    NASA-Langley has been conducting and sponsoring research in airborne energy management for a number of years. During the course of this research, two fundamental techniques for the generation of 4D (fixed time) descent trajectories have emerged as viable candidates for advanced flight management systems. The first technique utilizes speed schedules of constant Mach number transitioning to constant calibrated airspeed chosen empirically to produce minimum fuel usage. The second technique computes cost optimized speed schedules of variable airspeed developed through application of optimal control theory. Both techniques have been found to produce reasonable and flyable descent trajectories. The formulation of the algorithms for each technique is evaluated and their suitability for operations in realistic conditions is discussed. Operational factors considered include: airplace speed, thrust, and altitude rate constaints; wind, temperature, and pressure variations; Air Traffic Control altitude, speed, and time constaints; and pilot interface and guidance considerations. Time flexibility, fuel usage, and airborne computational requirements were the primary performance measures.

  10. A GIS-based simulation architecture and prototype for realistic spectral scene generation of vegetated areas

    Science.gov (United States)

    Fink, Christopher E.; Moulton, Joseph R., Jr.; Ortalano, Michael; Helmsen, John; Soiguine, Alexander; Kaplan, Raymond; Seng, William; Haren, Raymond E.

    2004-08-01

    Vehicles concealed in highly cluttered, vegetated scene environments pose significant challenges for passive sensor systems and algorithms. System analysts working hyperspectral exploitation research require an at-aperture simulation capability that allows them to reliably investigate beyond the highly-limited scenarios that expensive field data sets afford. To be useful to the analyst, such a simulation should address the following requirements: (1) the ability to easily generate scene representations for arbitrary Earth regions of tactical interest; (2) the ability to represent scene components, like terrain, trees and bushes, to an extremely high spatial resolution for calculation of accurate multiple spectral reflections, occlusions and shadowing; (3) the ability to stimulate the 3D scene with realistic natural spectral irradiances for arbitrary 3D model atmospheres; (4) the ability to appropriately integrate constantly improving, rigorous thermal, spectral signature and atmospheric propagation models; (5) the ability to efficiently render at-aperture hyperspectral data sets in a reasonable run-time. Herein the authors describe their work toward a comprehensive ray-tracer-based simulation architecture and prototype capability that addresses these requirements. They describe their development of a GIS-based toolset for database generation, tools for 3D vegetated terrain-model development, and a prototype raytracer-based spectral scene generator.

  11. Embedded generation connection incentives for distribution network operators

    Energy Technology Data Exchange (ETDEWEB)

    Williams, P.; Andrews, S.

    2002-07-01

    This is the final report with respect to work commissioned by the Department of Trade and Industry (DTI) as part of the New and Renewable Energy Programme into incentives for distribution network operators (DNOs) for the connection of embedded generation. This report, which incorporates the contents of the interim report submitted in February 2002, considers the implications of changes in the structure and regulation in the UK electricity industry on the successful technical and commercial integrated of embedded generation into distribution networks. The report examines: the obligations of public electricity suppliers (PESs); current DNO practices regarding the connection of embedded generation; the changes introduced by the Utilities Act 2000, including the impact of new obligations placed on DNOs on the connection of embedded generation and the requirements of the new Electricity Distribution Standard Licence conditions; and problems and prospects for DNO incentives.

  12. Grid-connected inverter for wind power generation system

    Institute of Scientific and Technical Information of China (English)

    YANG Yong; RUAN Yi; SHEN Huan-qing; TANG Yan-yan; YANG Ying

    2009-01-01

    In wind power generation system the grid-connected inverter is an important section for energy conversion and transmission, of which the performance has a direct influence on the entire wind power generation system. The mathematical model of the grid-connected inverter is deduced firstly. Then, the space vector pulse width modulation (SVPWM) is analyzed. The power factor can be controlled close to unity, leading or lagging, which is realized based on PI-type current controller and grid voltage vector-oriented control. The control strategy is verified by the simulation and experimental results with a good sinusoidal current, a small harmonic component and a fast dynamic response.

  13. Realistic three-generation models from SO(32) heterotic string theory

    CERN Document Server

    Abe, Hiroyuki; Otsuka, Hajime; Takano, Yasufumi

    2015-01-01

    We search for realistic supersymmetric standard-like models from SO(32) heterotic string theory on factorizable tori with multiple magnetic fluxes. Three chiral ganerations of quarks and leptons are derived from the adjoint and vector representations of SO(12) gauge groups embedded in SO(32) adjoint representation. Massless spectra of our models also include Higgs fields, which have desired Yukawa couplings to quarks and leptons at the tree-level.

  14. Is realistic neuronal modeling realistic?

    Science.gov (United States)

    Almog, Mara; Korngreen, Alon

    2016-11-01

    Scientific models are abstractions that aim to explain natural phenomena. A successful model shows how a complex phenomenon arises from relatively simple principles while preserving major physical or biological rules and predicting novel experiments. A model should not be a facsimile of reality; it is an aid for understanding it. Contrary to this basic premise, with the 21st century has come a surge in computational efforts to model biological processes in great detail. Here we discuss the oxymoronic, realistic modeling of single neurons. This rapidly advancing field is driven by the discovery that some neurons don't merely sum their inputs and fire if the sum exceeds some threshold. Thus researchers have asked what are the computational abilities of single neurons and attempted to give answers using realistic models. We briefly review the state of the art of compartmental modeling highlighting recent progress and intrinsic flaws. We then attempt to address two fundamental questions. Practically, can we realistically model single neurons? Philosophically, should we realistically model single neurons? We use layer 5 neocortical pyramidal neurons as a test case to examine these issues. We subject three publically available models of layer 5 pyramidal neurons to three simple computational challenges. Based on their performance and a partial survey of published models, we conclude that current compartmental models are ad hoc, unrealistic models functioning poorly once they are stretched beyond the specific problems for which they were designed. We then attempt to plot possible paths for generating realistic single neuron models. Copyright © 2016 the American Physiological Society.

  15. A Framework for the Generation of Realistic Synthetic Cardiac Ultrasound and Magnetic Resonance Imaging Sequences from the same Virtual Patients.

    Science.gov (United States)

    Zhou, Yitian; Giffard-Roisin, Sophie; De Craene, Mathieu; Camarasu-Pop, Sorina; D'hooge, Jan; Alessandrini, Martino; Friboulet, Denis; Sermesant, Maxime; Bernard, Olivier

    2017-05-25

    The use of synthetic sequences is one of the most promising tools for advanced in silico evaluation of the quantification of cardiac deformation and strain through 3D ultrasound (US) and magnetic resonance (MR) imaging. In this paper, we propose the first simulation framework which allows the generation of realistic 3D synthetic cardiac US and MR (both cine and tagging) image sequences from the same virtual patient. A state-of-the-art electromechanical (E/M) model was exploited for simulating groundtruth cardiac motion fields ranging from healthy to various pathological cases including both ventricular dyssynchrony and myocardial ischemia. The E/M groundtruth along with template MR/US images and physical simulators were combined in a unified framework for generating synthetic data. We efficiently merged several warping strategies to keep full control of myocardial deformations while preserving realistic image texture. In total, we generated 18 virtual patients, each with synthetic 3D US, cine MR and tagged MR sequences. The simulated images were evaluated both qualitatively by showing realistic textures and quantitatively by observing myocardial intensity distributions similar to real data. In particular, the US simulation showed a smoother myocardium/background interface than the state-of-the-art. We also assessed the mechanical properties. The pathological subjects were discriminated from the healthy ones by both global indexes (ejection fraction and the global circumferential strain) and regional strain curves. The synthetic database is comprehensive in terms of both pathology and modality, and has a level of realism sufficient for validation purposes. All the 90 sequences are made publicly available to the research community via an open-access database.

  16. Improved Power Decoupling Scheme for Single-Phase Grid-Connected Differential Inverter with Realistic Mismatch in Storage Capacitances

    DEFF Research Database (Denmark)

    Yao, Wenli; Wang, Xiongfei; Loh, Poh Chiang;

    2017-01-01

    A single-phase differential inverter consists of two elementary dc-dc converters, sharing a common dc source and a common ac output terminal. The other ac terminals of the two converters are connected to the grid in the case of grid-connected applications. The differential inverter has subsequent...... provided have verified the computation and control scheme developed....

  17. A Vector Control for Grid-connected Wind Power Generation with Doubly Fed Induction Generator

    Science.gov (United States)

    Kai, Takaaki; Tanaka, Yuji; Kaneda, Hirotoshi; Kobayashi, Daichi; Tanaka, Akio

    Recently, doubly fed induction generator (DFIG) and synchronous generator are mostly applied for wind power generation due to high efficiently for wind energy capture. An inverter system is required to control wind turbine speed and power factor in those generators. The inverter rating of the synchronous generator equals to generator rating. However, DFIG has the advantage that the inverter rating is about 25% to the generator rating. The paper describes a vector control of DFIG inter-connected to power line. The performance of proposed vector control is examined using power system simulation software PSCAD/EMTDC for the DFIG inter-connected to 6.6kv distribution line. The results show good dynamic responses and high accuracy to the stator active power control and the stator reactive power control.

  18. Generation of realistic tsunami waves using a bottom-tilting wave maker

    Science.gov (United States)

    Park, Yong Sung; Hwang, Jin Hwan

    2016-11-01

    Tsunamis have caused more than 260,000 human losses and 250 billion in damage worldwide in the last ten years. Observations made during 2011 Japan Tohoku Tsunami revealed that the commonly used waves (solitary waves) to model tsunamis are at least an order-of-magnitude shorter than the real tsunamis, which calls for re-evaluation of the current understanding of tsunamis. To prompt the required paradigm shift, a new wave generator, namely the bottom-tilting wave generator, has been developed at the University of Dundee. The wave tank is fitted with an adjustable slope and a bottom flap hinged at the beginning of the slope. By moving the bottom flap up and down, we can generate very long waves. Here we will report characteristics of waves generated by simple bottom motions, either moving it upward or downward from an initial displacement ending it being horizontal. Two parameters, namely the initial displacement of the bottom and the speed of the motion, determine characteristics of the generated waves. Wave amplitudes scale well with the volume flux of the displaced water. On the other hand, due to combined effects of nonlinearity and dispersion, wavelengths show more complicated relationship with the two bottom motion parameters. We will also demonstrate that by combining simple up and down motions, it is possible to generate waves resembling the one measured during 2011 tsunami. YSP acknowledges financial support from the Royal Society of Edinburgh through the Royal Society of Edinburgh and Scottish Government Personal Research Fellowship Co-Funded by the Marie-Curie Actions.

  19. A generic approach to generating optimal controlled prespective route guidance in realistic traffic networks

    NARCIS (Netherlands)

    Chen, Y.; Zuurbier, F.S.; Zuylen, H.J. van; Hoogendoorn, S.P.

    2006-01-01

    This paper presents a generic methodology to generate optimal controlled dynamic prescriptive route guidance to be disseminated by means of variable message signs (VMS). The methodology is generic in the sense it can be used on any network topology and network model, with any number of VMS’s, for di

  20. Large-scale, realistic laboratory modeling of M2 internal tide generation at the Luzon Strait

    CERN Document Server

    Mercier, Matthieu J; Helfrich, Karl; Sommeria, Joël; Viboud, Samuel; Didelle, Henri; Saidi, Sasan; Dauxois, Thierry; Peacock, Thomas

    2015-01-01

    The complex double-ridge system in the Luzon Strait in the South China Sea (SCS) is one of the strongest sources of internal tides in the oceans, associated with which are some of the largest amplitude internal solitary waves on record. An issue of debate, however, has been the specific nature of their generation mechanism. To provide insight, we present the results of a large-scale laboratory experiment performed at the Coriolis platform. The experiment was carefully designed so that the relevant dimensionless parameters, which include the excursion parameter, criticality, Rossby, and Froude numbers, closely matched the ocean scenario. The results advocate that a broad and coherent weakly nonlinear, three-dimensional, M2 internal tide that is shaped by the overall geometry of the double-ridge system is radiated into the South China Sea and subsequently steepens, as opposed to being generated by a particular feature or localized region within the ridge system.

  1. Remembrance of phases past: An autoregressive method for generating realistic atmospheres in simulations

    Science.gov (United States)

    Srinath, Srikar; Poyneer, Lisa A.; Rudy, Alexander R.; Ammons, S. M.

    2014-08-01

    The advent of expensive, large-aperture telescopes and complex adaptive optics (AO) systems has strengthened the need for detailed simulation of such systems from the top of the atmosphere to control algorithms. The credibility of any simulation is underpinned by the quality of the atmosphere model used for introducing phase variations into the incident photons. Hitherto, simulations which incorporate wind layers have relied upon phase screen generation methods that tax the computation and memory capacities of the platforms on which they run. This places limits on parameters of a simulation, such as exposure time or resolution, thus compromising its utility. As aperture sizes and fields of view increase the problem will only get worse. We present an autoregressive method for evolving atmospheric phase that is efficient in its use of computation resources and allows for variability in the power contained in frozen flow or stochastic components of the atmosphere. Users have the flexibility of generating atmosphere datacubes in advance of runs where memory constraints allow to save on computation time or of computing the phase at each time step for long exposure times. Preliminary tests of model atmospheres generated using this method show power spectral density and rms phase in accordance with established metrics for Kolmogorov models.

  2. Simulation of Photovoltaic generator Connected To a Grid

    Directory of Open Access Journals (Sweden)

    F. Slama

    2014-03-01

    Full Text Available This paper presents the mathematical and the total Matlab-simulink model of the various components, of the photovoltaic power station connected to a network, (PSCN, namely the model of the photovoltaic generator. It is a comprehensive behavioural study which performed according to varying conditions of solar insulation and temperature. The photovoltaic generator and the inverter of single-phase current are modeled. The former by using a mathematical model that gives the values of maximum power according to the variation of the weather conditions, and the latter by a source of voltage controlled by voltage in order to inject a sinusoidal current and to estimate or predict the energy injected monthly or annually into the network.

  3. Facilitate generation connections on Orkney by automatic distribution network management

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    This report summarises the results of a study assessing the capability and limitations of the Orkney Network under a variety of conditions of demand, generation connections, network configuration, and reactive compensation). A conceptual active management scheme (AMS) suitable for the conditions on Orkney is developed and evaluated. Details are given of a proposed framework for the design and evaluation of future active management schemes, logic control sequences for managed generation units, and a proposed evaluation method for the active management scheme. Implications of introducing the proposed AMS are examined, and the commercial aspects of an AMS and system security are considered. The existing Orkney network is described; and an overview of the SHEPDL (Scottish Hydro Electric Power Distribution Ltd.) SCADA system is presented with a discussion of AMS identification, selection, and development.

  4. Facilitate generation connections on Orkney by automatic distribution network management

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    This report summarises the results of a study assessing the capability and limitations of the Orkney Network under a variety of conditions of demand, generation connections, network configuration, and reactive compensation). A conceptual active management scheme (AMS) suitable for the conditions on Orkney is developed and evaluated. Details are given of a proposed framework for the design and evaluation of future active management schemes, logic control sequences for managed generation units, and a proposed evaluation method for the active management scheme. Implications of introducing the proposed AMS are examined, and the commercial aspects of an AMS and system security are considered. The existing Orkney network is described; and an overview of the SHEPDL (Scottish Hydro Electric Power Distribution Ltd.) SCADA system is presented with a discussion of AMS identification, selection, and development.

  5. Generation of realistic virtual nodules based on three-dimensional spatial resolution in lung computed tomography: A pilot phantom study.

    Science.gov (United States)

    Narita, Akihiro; Ohkubo, Masaki; Murao, Kohei; Matsumoto, Toru; Wada, Shinichi

    2017-08-04

    The aim of this feasibility study using phantoms was to propose a novel method for obtaining computer-generated realistic virtual nodules in lung computed tomography (CT). In the proposed methodology, pulmonary nodule images obtained with a CT scanner are deconvolved with the point spread function (PSF) in the scan plane and slice sensitivity profile (SSP) measured for the scanner; the resultant images are referred to as nodule-like object functions. Next, by convolving the nodule-like object function with the PSF and SSP of another (target) scanner, the virtual nodule can be generated so that it has the characteristics of the spatial resolution of the target scanner. To validate the methodology, the authors applied physical nodules of 5-, 7- and 10-mm-diameter (uniform spheres) included in a commercial CT test phantom. The nodule-like object functions were calculated from the sphere images obtained with two scanners (Scanner A and Scanner B); these functions were referred to as nodule-like object functions A and B, respectively. From these, virtual nodules were generated based on the spatial resolution of another scanner (Scanner C). By investigating the agreement of the virtual nodules generated from the nodule-like object functions A and B, the equivalence of the nodule-like object functions obtained from different scanners could be assessed. In addition, these virtual nodules were compared with the real (true) sphere images obtained with Scanner C. As a practical validation, five types of laboratory-made physical nodules with various complicated shapes and heterogeneous densities, similar to real lesions, were used. The nodule-like object functions were calculated from the images of these laboratory-made nodules obtained with Scanner A. From them, virtual nodules were generated based on the spatial resolution of Scanner C and compared with the real images of laboratory-made nodules obtained with Scanner C. Good agreement of the virtual nodules generated from

  6. Power Smoothing and MPPT for Grid-connected Wind Power Generation with Doubly Fed Induction Generator

    Science.gov (United States)

    Kai, Takaaki; Tanaka, Yuji; Kaneda, Hirotoshi; Kobayashi, Daichi; Tanaka, Akio

    Recently, doubly fed induction generator (DFIG) and synchronous generator are mostly applied for wind power generation, and variable speed control and power factor control are executed for high efficiently for wind energy capture and high quality for power system voltage. In variable speed control, a wind speed or a generator speed is used for maximum power point tracking. However, performances of a wind generation power fluctuation due to wind speed variation have not yet investigated for those controls. The authors discuss power smoothing by those controls for the DFIG inter-connected to 6.6kV distribution line. The performances are verified using power system simulation software PSCAD/EMTDC for actual wind speed data and are examined from an approximate equation of wind generation power fluctuation for wind speed variation.

  7. Vortex generated fluid flows in multiply connected domains

    CERN Document Server

    Zemlyanova, Anna; Handley, Demond

    2016-01-01

    A fluid flow in a multiply connected domain generated by an arbitrary number of point vortices is considered. A stream function for this flow is constructed as a limit of a certain functional sequence using the method of images. The convergence of this sequence is discussed, and the speed of convergence is determined explicitly. The presented formulas allow for the easy computation of the values of the stream function with arbitrary precision in the case of well-separated cylinders. The considered problem is important for applications such as eddy flows in the oceans. Moreover, since finding the stream function of the flow is essentially identical to finding the modified Green's function for Laplace's equation, the presented method can be applied to a more general class of applied problems which involve solving the Dirichlet problem for Laplace's equation.

  8. Computation of a leakage in a stream generator heating tube with realistic initial and boundary conditions; Berechnung eines Dampferzeugerheizrohrlecks mit realistischen Anfangs- und Randbedingungen

    Energy Technology Data Exchange (ETDEWEB)

    Sarkadi, Peter; Schaffrath, Andreas [TUEV NORD SysTec GmbH und Co. KG, Hamburg (Germany)

    2009-02-15

    Within the framework of the safety review of a pressurized water reactor, TUeV NORD SysTec GmbH and Co.KG analyzed plant behavior for the case of a leakage in a steam generator heating tube by means of the ATHLET thermohydraulic code system using realistic initial and boundary conditions. The analysis was performed to show that operation of the safety injection pumps avoids 2 out of 3 emergency cooling criteria being triggered. After coolant transfer from the primary to the secondary side, activity retention is ensured only if the coolant is contained by the components of the secondary system. This requires the pressure in the failed steam generator to remain below the level of 88.3 bar at which the safety valves respond. Startup of the safety injection pumps would jeopardize activity retention because of the zero head of these pumps. Analysis indicated the filling level of the pressurizer to be above 3.6 m during the accident. The minimum margin from the ''pressurizer level <2.28 m'' reactor protection limit is around 1.3 m. Consequently, only the first of the 3 emergency cooling criteria (in this case, 'coolant pressure <132 bar') will respond. This avoids unwanted boosting of the coolant pressure due to connection of the safety injection pumps. By the end of the period of observation, approx. 36 Mg of coolant are transferred to the secondary side. Activity retention is ensured by the components of the secondary system. (orig.)

  9. Time series power flow analysis for distribution connected PV generation.

    Energy Technology Data Exchange (ETDEWEB)

    Broderick, Robert Joseph; Quiroz, Jimmy Edward; Ellis, Abraham; Reno, Matthew J.; Smith, Jeff; Dugan, Roger

    2013-01-01

    Distributed photovoltaic (PV) projects must go through an interconnection study process before connecting to the distribution grid. These studies are intended to identify the likely impacts and mitigation alternatives. In the majority of the cases, system impacts can be ruled out or mitigation can be identified without an involved study, through a screening process or a simple supplemental review study. For some proposed projects, expensive and time-consuming interconnection studies are required. The challenges to performing the studies are twofold. First, every study scenario is potentially unique, as the studies are often highly specific to the amount of PV generation capacity that varies greatly from feeder to feeder and is often unevenly distributed along the same feeder. This can cause location-specific impacts and mitigations. The second challenge is the inherent variability in PV power output which can interact with feeder operation in complex ways, by affecting the operation of voltage regulation and protection devices. The typical simulation tools and methods in use today for distribution system planning are often not adequate to accurately assess these potential impacts. This report demonstrates how quasi-static time series (QSTS) simulation and high time-resolution data can be used to assess the potential impacts in a more comprehensive manner. The QSTS simulations are applied to a set of sample feeders with high PV deployment to illustrate the usefulness of the approach. The report describes methods that can help determine how PV affects distribution system operations. The simulation results are focused on enhancing the understanding of the underlying technical issues. The examples also highlight the steps needed to perform QSTS simulation and describe the data needed to drive the simulations. The goal of this report is to make the methodology of time series power flow analysis readily accessible to utilities and others responsible for evaluating

  10. SU-E-J-126: Generation of Fluoroscopic 3D Images Using Single X-Ray Projections on Realistic Modified XCAT Phantom Data.

    Science.gov (United States)

    Mishra, P; Li, R; St James, S; Yue, Y; Mak, R; Berbeco, R; Lewis, J

    2012-06-01

    To simulate the process of generating fluoroscopic 3D treatment images from 4DCT and measured 2D x-ray projections using a realistic modified XCAT phantom based on measured patient 3D tumor trajectories. First, the existing XCAT phantom is adapted to incorporate measured patient lung tumor trajectories. Realistic diaphragm and chest wall motion are automatically generated based on input tumor motion and position, producing synchronized, realistic motion in the phantom. Based on 4DCT generated with the XCAT phantom, we derive patient-specific motion models that are used to generate 3D fluoroscopic images. Patient-specific models are created in two steps: first, the displacement vector fields (DVFs) are obtained through deformable image registration of each phase of 4DCT with respect to a reference image (typically peak-exhale). Each phase is registered to the reference image to obtain (n-1) DVFs. Second, the most salient characteristics in the DVFs are captured in a compact representation through principal component analysis (PCA). Since PCA is a linear decomposition method, all the DVFs can be represented as linear combinations of eigenvectors. Fluoroscopic 3D images are obtained using the projection image to determine optimal weights for the eigenvectors. These weights are determined through iterative optimization of a cost function relating the projection image to the 3D image via the PCA lung motion model and a projection operator. Constructing fluoroscopic 3D images is thus reduced to finding optimal weights for the eigenvectors. Fluoroscopic 3D treatment images were generated using the modified XCAT phantom. The average relative error of the reconstructed image over 30 sec is 0.0457 HU and the standard deviation is 0.0063. The XCAT phantom was modified to produce realistic images by incorporating patient tumor trajectories. The modified XCAT phantom can be used to simulate the process of generating fluoroscopic 3D treatment images from 4DCT and 2D x

  11. Connecting the Generations: Memory, Magic, and Harry Potter.

    Science.gov (United States)

    Radigan, Winifred M.

    2001-01-01

    Explains that the author reads the Harry Potter books because of their impact on middle-school-age kids and their appeal to children ages 9 to 15. Explains also that she works in professional development, especially literacy, and that she connects kids and teachers to the books. Admits that she reads the books because "they are wonderful." (SG)

  12. Connecting the Generations: Memory, Magic, and Harry Potter.

    Science.gov (United States)

    Radigan, Winifred M.

    2001-01-01

    Explains that the author reads the Harry Potter books because of their impact on middle-school-age kids and their appeal to children ages 9 to 15. Explains also that she works in professional development, especially literacy, and that she connects kids and teachers to the books. Admits that she reads the books because "they are wonderful." (SG)

  13. Efficient generation of connectivity in neuronal networks from simulator-independent descriptions

    Directory of Open Access Journals (Sweden)

    Mikael eDjurfeldt

    2014-04-01

    Full Text Available Simulator-independent descriptions of connectivity in neuronal networks promise greater ease of model sharing, improved reproducibility of simulation results, and reduced programming effort for computational neuroscientists. However, until now, enabling the use of such descriptions in a given simulator in a computationally efficient way has entailed considerable work for simulator developers, which must be repeated for each new connectivity-generating library that is developed.We have developed a generic connection generator interface that provides a standard way to connect a connectivity-generating library to a simulator, such that one library can easily be replaced by another, according to the modeller's needs. We have used the connection generator interface to connect C++ and Python implementations of the connection-set algebra to the NEST simulator. We also demonstrate how the simulator-independent modelling framework PyNN can transparently take advantage of this, passing a connection description through to the simulator layer for rapid processing in C++ where a simulator supports the connection generator interface and falling-back to slower iteration in Python otherwise. A set of benchmarks demonstrates the good performance of the interface.

  14. Efficient generation of connectivity in neuronal networks from simulator-independent descriptions.

    Science.gov (United States)

    Djurfeldt, Mikael; Davison, Andrew P; Eppler, Jochen M

    2014-01-01

    Simulator-independent descriptions of connectivity in neuronal networks promise greater ease of model sharing, improved reproducibility of simulation results, and reduced programming effort for computational neuroscientists. However, until now, enabling the use of such descriptions in a given simulator in a computationally efficient way has entailed considerable work for simulator developers, which must be repeated for each new connectivity-generating library that is developed. We have developed a generic connection generator interface that provides a standard way to connect a connectivity-generating library to a simulator, such that one library can easily be replaced by another, according to the modeler's needs. We have used the connection generator interface to connect C++ and Python implementations of the previously described connection-set algebra to the NEST simulator. We also demonstrate how the simulator-independent modeling framework PyNN can transparently take advantage of this, passing a connection description through to the simulator layer for rapid processing in C++ where a simulator supports the connection generator interface and falling-back to slower iteration in Python otherwise. A set of benchmarks demonstrates the good performance of the interface.

  15. Hysteresis Control for a DC Connected Synchronous Generator

    DEFF Research Database (Denmark)

    Rasmussen, Tonny Wederberg; Evangelos, Dimarakis

    2009-01-01

    Abstract— for offshore wind farms the distance to the coast increases, therefore DC cables will have to be used. For a variable speed wind turbine a rectifier and a synchronous generator with a boost converter is used. As a new suggestion for control the generator speed hysteresis control...

  16. Computation of a leakage in a stream generator heating tube with realistic initial and boundary conditions; Berechnung eines Dampferzeugerheizrohrlecks mit realistischen Anfangs- und Randbedingungen

    Energy Technology Data Exchange (ETDEWEB)

    Sarkadi, Peter; Schaffrath, Andreas [TUeV NORD SysTec GmbH und Co. KG, Hamburg (Germany)

    2009-07-01

    In the frame of a PWR reactor safety analysis the TUEV Nord Sys Tec GmbH has analyzed the plant behavior in case of a steam generator tube leakage using the thermal hydraulic code ATHLET and realistic initial and boundary conditions. The aim of the analysis was to show that the response of the emergency cooling criteria including the activation of safety injection pumps can be avoided. The Activation of the safety injection pumps could jeopardize the activity retention.

  17. Issues and regulatory requirements for the connection of wind generation

    Energy Technology Data Exchange (ETDEWEB)

    Gimenez Alvarez, J.M. [National University of San Juan (Argentina)], E-mail: jgimenez@unsj.edu.ar; Gomez Targarona, J.C. [National University of Rio Cuarto, Cordoba (Argentina). Electric Power Systems Protection Institute (IPSEP)], E-mail: jcgomez@ing.unrc.edu.ar

    2009-07-01

    Pollution problems such as greenhouse effect as well as the high value and volatility of fuel prices have forced and accelerated the development and use of renewable energy sources. In this work a complete revision of wind generation is presented. In the first part a brief history of the wind energy developments is detailed. Next, some commentaries related to the present and future state are made. Then, a revision of the modern structures of wind generation is realized. In fourth place it is included a brief comparison between small and big size turbines. Then, different types of energy storage are mentioned. Finally regulatory aspects are discussed, respect to the treatment of the technical problems. (author)

  18. Special issue on advancing grid-connected renewable generation systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Yang, Yongheng

    2017-01-01

    Renewables are heavily involved in power generation, as an essential component for today’s energy paradigm. Energy structure—both national and international—has been undergoing significant changes over the past few decades. For instance, in Denmark, power generation is shifting from fossil......-fuel-based to renewable-based in terms of energy sources, from centralized to decentralized in terms of architectures, and from sole to miscellaneous in terms of energy varieties [1]. In this energy evolution, the power electronic technology plays an enabling role in the integration and advancements of renewables......—such as wind turbine, photovoltaics, fuel cells, and other emerging energy systems. At the same time, various control strategies are necessary to guide the energy integration (i.e., to enhance the energy transition), and on the other hand, to flexibly, reliably, and efficiently utilize the energy. Tremendous...

  19. Fast clique minor generation in Chimera qubit connectivity graphs

    Science.gov (United States)

    Boothby, Tomas; King, Andrew D.; Roy, Aidan

    2016-01-01

    The current generation of D-Wave quantum annealing processor is designed to minimize the energy of an Ising spin configuration whose pairwise interactions lie on the edges of a Chimera graph C_{M,N,L}. In order to solve an Ising spin problem with arbitrary pairwise interaction structure, the corresponding graph must be minor-embedded into a Chimera graph. We define a combinatorial class of native clique minors in Chimera graphs with vertex images of uniform, near minimal size and provide a polynomial-time algorithm that finds a maximum native clique minor in a given induced subgraph of a Chimera graph. These minors allow improvement over recent work and have immediate practical applications in the field of quantum annealing.

  20. Connection between solar activity cycles and grand minima generation

    Science.gov (United States)

    Vecchio, A.; Lepreti, F.; Laurenza, M.; Alberti, T.; Carbone, V.

    2017-03-01

    Aims: The revised dataset of sunspot and group numbers (released by WDC-SILSO) and the sunspot number reconstruction based on dendrochronologically dated radiocarbon concentrations have been analyzed to provide a deeper characterization of the solar activity main periodicities and to investigate the role of the Gleissberg and Suess cycles in the grand minima occurrence. Methods: Empirical mode decomposition (EMD) has been used to isolate the time behavior of the different solar activity periodicities. A general consistency among the results from all the analyzed datasets verifies the reliability of the EMD approach. Results: The analysis on the revised sunspot data indicates that the highest energy content is associated with the Schwabe cycle. In correspondence with the grand minima (Maunder and Dalton), the frequency of this cycle changes to longer timescales of 14 yr. The Gleissberg and Suess cycles, with timescales of 60-120 yr and 200-300 yr, respectively, represent the most energetic contribution to sunspot number reconstruction records and are both found to be characterized by multiple scales of oscillation. The grand minima generation and the origin of the two expected distinct types of grand minima, Maunder and longer Spörer-like, are naturally explained through the EMD approach. We found that the grand minima sequence is produced by the coupling between Gleissberg and Suess cycles, the latter being responsible for the most intense and longest Spörer-like minima (with typical duration longer than 80 yr). Finally, we identified a non-solar component, characterized by a very long scale oscillation of 7000 yr, and the Hallstatt cycle ( 2000 yr), likely due to the solar activity. Conclusions: These results provide new observational constraints on the properties of the solar cycle periodicities, the grand minima generation, and thus the long-term behavior of the solar dynamo.

  1. System efficiency of a tap transformer based grid connection topology applied on a direct driven generator for wind power.

    Science.gov (United States)

    Apelfröjd, Senad; Eriksson, Sandra

    2014-01-01

    Results from experiments on a tap transformer based grid connection system for a variable speed vertical axis wind turbine are presented. The tap transformer based system topology consists of a passive diode rectifier, DC-link, IGBT inverter, LCL-filter, and tap transformer. Full range variable speed operation is enabled by using the different step-up ratios of a tap transformer. Simulations using MATLAB/Simulink have been performed in order to study the behavior of the system. A full experimental set up of the system has been used in the laboratory study, where a clone of the on-site generator was driven by an induction motor and the system was connected to a resistive load to better evaluate the performance. Furthermore, the system is run and evaluated for realistic wind speeds and variable speed operation. For a more complete picture of the system performance, a case study using real site Weibull parameters is done, comparing different tap selection options. The results show high system efficiency at nominal power and an increase in overall power output for full tap operation in comparison with the base case, a standard transformer. In addition, the loss distribution at different wind speeds is shown, which highlights the dominant losses at low and high wind speeds. Finally, means for further increasing the overall system efficiency are proposed.

  2. ASP - Grid connections of large power generating units; ASP - Anslutning av stoerre produktionsanlaeggningar till elnaetet

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, Aake; Larsson, Richard [Vattenfall Power Consultants, Stockholm (Sweden)

    2006-12-15

    Grid connections of large power generating units normally require more detailed studies compared to small single units. The required R and D-level depends on the specific characteristics of the production units and the connecting grid. An inquiry for a grid connection will raise questions for the grid owner regarding transmission capability, losses, fault currents, relay protection, dynamic stability etc. Then only a few larger wind farms have been built, the experiences from these types of grid connections are limited and for that reason it can be difficult to identify issues appropriate for further studies. To ensure that electric power generating units do not have unacceptable impact on the grid, directions from the Swedish TSO (Svenska Kraftnaet) have been stated. The directions deal, for example, with power generation in specific ranges of voltage level and frequency and the possibility to remain connected to the grid when different faults occur. The requirements and the consequences of these directions are illustrated. There are three main issues that should be considered: Influence on the power flow from generating units regarding voltage level, currents, losses etc.; Different types of electric systems in generating units contribute to different levels of fault currents. For that reason the resulting fault current levels have to be studied; It is required that generating units should remain connected to the grid at different modes of operation and faults. These modes have to be verified. Load flow and dynamic studies normally demand computer models. Comprehensive models, for instance of wind farms, can bee difficult to design and normally large computer capacity is required. Therefore simplified methods to perform relevant studies are described. How to model an electric power generating unit regarding fault currents and dynamic stability is described. An inquiry for a grid connection normally brings about a discussion concerning administration. To make it

  3. Performance analysis of commercial scale Ar-Cs disk MHD generator connected to electric power system with synchronous generator

    Energy Technology Data Exchange (ETDEWEB)

    Kang, L.; Matsuo, T. [Kyoto University (Japan). Dept. of Electrical Engineering; Inui, Y. [Toyohashi University of Technology (Japan). Dept. of Electrical and Electronic Engineering; Ishikawa, M. [University of Tsukuba (Japan). Inst. of Engineering Mechanics and Systems; Umoto, J. [Fukuyama University (Japan)

    2000-09-01

    Performance analyses of a commercial scale closed-cycle MHD disk generator are performed. A large scale MHD generator, superconducting magnet, inversion system and synchronous generator are designed. The MHD generator is operated with Ar-Cs plasma and connected to the ac power infinite bus through line-commutated inverters, while the synchronous generator is operated in parallel. The thermal input is 1000 MW, and the power output is 400 and 200 MW, from the MHD and synchronous generators. Fault analyses have found that rather large fluctuations within the MHD generator are induced by faults of the inverter and power transmission line, but control of the inverters can recover the MHD generation system to normal operation within 0.15 s. The feature of behavior of the MHD generator is the same with or without the parallel operation of the synchronous generator. The interaction between the MHD and the synchronous generators is small, and this feature is much different from the open-cycle MHD generation system, since the variation of output current of the closed-cycle disk MHD generator is much smaller compared with open-cycle MHD generators. (author)

  4. Control strategies for gas turbine generators for grid connected and islanding operations

    DEFF Research Database (Denmark)

    Mahat, Pukar; Chen, Zhe; Bak-Jensen, Birgitte

    2010-01-01

    Islanding operation of distribution systems with distributed generations (DG) is becoming a viable option for economical and technical reasons. However, there are various issues to be resolved before it can be a reality. One of the main issues is control of the DG. Control strategies, that may work...... fine while a DG is connected to a grid, might not work as desired while it is islanded and vise versa. This paper presents a strategy to operate distribution systems with a small gas turbine generator (GTG), which is capable of supplying local loads, in both islanding and grid connected conditions....... Separate strategies are used to control the GTG while it is connected to the grid and while it is islanded. Switching between the control strategies is achieved through a state detection algorithm that includes islanding and grid re-connection detections. An existing islanding detection technique has been...

  5. Modelling and simulation of load connected fixed blade wind turbine with permanent magnet synchronous generators

    OpenAIRE

    Al-Toma, AS; Taylor, GA; Abbod, M

    2015-01-01

    This paper presents the modelling and simulation of a wind turbine driven Permanent Magnet Synchronous Generator connected to a load. The system has been tested at different wind speeds. The machine side controller has been designed to match Maximum Power Point Tracking (MPPT) to obtain high extraction of wind power when connected to a load, while the load side controller fixes the DC voltage that is converted to the AC load voltage. Detailed plots of voltage and current profiles are also pre...

  6. Inrush Current Limitation in Wind Generators by SCR Based Soft-starter during grid connection

    Directory of Open Access Journals (Sweden)

    Sanjay Mishra

    2013-10-01

    Full Text Available High Inrush current & harmonics is a generic problem wind generators during grid connection.The designed SCR based soft-starter successfully limits the high inrush current during the connection of the wind-turbine system to the grid. The proposed SCR based soft starter using will be simulating in PSCAD on a three-phase induction generator. Expected results will show a significant reduction in high inrush current and smooth connection of the three phase induction generator to the grid with small impact on the power quality. A small-scale wind turbine coupled three phase induction generator is an attractive choice for an isolated grid hybrid power system in remote areas because of its low cost, compactness, ruggedness, high reliability, low inertia and ease in control. In this work, a SCR based soft starter for limiting the high inrush current during the connection of the small-scale wind turbine coupled three phase induction generator to an isolated weak grid has been proposed. Soft-starter is designed to reduce inrush current or surge in current while achieving a proper synchronism between the generator and the grid.

  7. Fatigue damage of steam turbine shaft at asynchronous connections of turbine generator to electrical network

    Science.gov (United States)

    Bovsunovsky, A. P.

    2015-07-01

    The investigations of cracks growth in the fractured turbine rotors point out at theirs fatigue nature. The main reason of turbine shafts fatigue damage is theirs periodical startups which are typical for steam turbines. Each startup of a turbine is accompanied by the connection of turbine generator to electrical network. During the connection because of the phase shift between the vector of electromotive force of turbine generator and the vector of supply-line voltage the short-term but powerful reactive shaft torque arises. This torque causes torsional vibrations and fatigue damage of turbine shafts of different intensity. Based on the 3D finite element model of turbine shaft of the steam turbine K-200-130 and the mechanical properties of rotor steel there was estimated the fatigue damage of the shaft at its torsional vibrations arising as a result of connection of turbine generator to electric network.

  8. Noise, transient dynamics, and the generation of realistic interspike interval variation in square-wave burster neurons

    Science.gov (United States)

    Marin, Bóris; Pinto, Reynaldo Daniel; Elson, Robert C.; Colli, Eduardo

    2014-10-01

    First return maps of interspike intervals for biological neurons that generate repetitive bursts of impulses can display stereotyped structures (neuronal signatures). Such structures have been linked to the possibility of multicoding and multifunctionality in neural networks that produce and control rhythmical motor patterns. In some cases, isolating the neurons from their synaptic network reveals irregular, complex signatures that have been regarded as evidence of intrinsic, chaotic behavior. We show that incorporation of dynamical noise into minimal neuron models of square-wave bursting (either conductance-based or abstract) produces signatures akin to those observed in biological examples, without the need for fine tuning of parameters or ad hoc constructions for inducing chaotic activity. The form of the stochastic term is not strongly constrained and can approximate several possible sources of noise, e.g., random channel gating or synaptic bombardment. The cornerstone of this signature generation mechanism is the rich, transient, but deterministic dynamics inherent in the square-wave (saddle-node and homoclinic) mode of neuronal bursting. We show that noise causes the dynamics to populate a complex transient scaffolding or skeleton in state space, even for models that (without added noise) generate only periodic activity (whether in bursting or tonic spiking mode).

  9. The need to generate realistic strain signals at an automotive coil spring for durability simulation leading to fatigue life assessment

    Science.gov (United States)

    Putra, T. E.; Abdullah, S.; Schramm, D.; Nuawi, M. Z.; Bruckmann, T.

    2017-09-01

    This study aims to accelerate fatigue tests using simulated strain signals. Strain signals were acquired from a coil spring involving car movements. Using a mathematical expression, the measured strain signals yielded acceleration signals, and were considered as disturbances on generating strain signals. The simulated strain signals gave the testing time deviation by only 1.5%. The wavelet-based data editing was applied to shorten the strain signals time up to 36.7% and reduced the testing time up to 33.9%. In conclusion, the simulated strain signals were able to maintain the majority of fatigue damage and decreased the testing time.

  10. Voltage Stability Improvement of Grid Connected Wind Driven Induction Generator Using Svc

    Directory of Open Access Journals (Sweden)

    Ruchi Aggarwal

    2014-05-01

    Full Text Available Voltage stability is one of the major problem associated with wind power generating system which may be due to fluctuating nature of wind, heavy load, fault occurrence or insufficient reactive power supply. The wind power generating system most commonly employed with squirrel cage induction generator(SCIG that needs the support of an external device such as capacitor bank, FACTS devices etc. to support reactive power in order to remain connected with the grid during voltage dips. The voltage stability of a wind driven induction generator can be improved by using FACTS devices such as SVC, STATCOM.In this paper svc is used for voltage stability improvement.

  11. Connection and Commitment: Exploring the Generation and Experience of Emotion in a Participatory Drama

    Science.gov (United States)

    Dunn, Julie; Bundy, Penny; Stinson, Madonna

    2015-01-01

    Emotion is a complex and important aspect of participatory drama experience. This is because drama work of this kind provokes emotional responses to both actual and dramatic worlds. This paper identifies two key features of participatory drama that influence the generation and experience of emotion: commitment and connection. These features are…

  12. Reaching the Connected Generation: "College Access Marketers" Slow in Adopting New Techniques

    Science.gov (United States)

    Gastwirth, David

    2007-01-01

    This author states that "college access marketing" efforts aimed at increasing college attendance and success have been slow to incorporate new techniques such as "buzz marketing," "viral marketing," "product seeding," and "guerrilla marketing." Yet for a "connected generation" of potential college students, these kinds of strategies could be…

  13. A Fast Component-Tree Algorithm for High Dynamic-Range Images and Second Generation Connectivity

    NARCIS (Netherlands)

    Wilkinson, Michael H.F.

    2011-01-01

    Component trees are important data structures for computation of connected attribute filters. Though some of the available algorithms are suitable for high-dynamic range, and in particular floating point data, none are suitable for computation of component trees for so-called second-generation, and

  14. Development of Adult-Generated Cell Connectivity with Excitatory and Inhibitory Cell Populations in the Hippocampus.

    Science.gov (United States)

    Restivo, Leonardo; Niibori, Yosuke; Mercaldo, Valentina; Josselyn, Sheena A; Frankland, Paul W

    2015-07-22

    New neurons are generated continuously in the subgranular zone of the hippocampus and integrate into existing hippocampal circuits throughout adulthood. Although the addition of these new neurons may facilitate the formation of new memories, as they integrate, they provide additional excitatory drive to CA3 pyramidal neurons. During development, to maintain homeostasis, new neurons form preferential contacts with local inhibitory circuits. Using retroviral and transgenic approaches to label adult-generated granule cells, we first asked whether a comparable process occurs in the adult hippocampus in mice. Similar to development, we found that, during adulthood, new neurons form connections with inhibitory cells in the dentate gyrus, hilus, and CA3 regions as they integrate into hippocampal circuits. In particular, en passant bouton and filopodia connections with CA3 interneurons peak when adult-generated dentate granule cells (DGCs) are ∼4 weeks of age, a time point when these cells are most excitable. Consistent with this, optical stimulation of 4-week-old (but not 6- or 8-week-old) adult-generated DGCs strongly activated CA3 interneurons. Finally, we found that CA3 interneurons were activated robustly during learning and that their activity was strongly coupled with activity of 4-week-old (but not older) adult-generated DGCs. These data indicate that, as adult-generated neurons integrate into hippocampal circuits, they transiently form strong anatomical, effective, and functional connections with local inhibitory circuits in CA3. Significance statement: New neurons are generated continuously in the subgranular zone of the hippocampus and integrate into existing hippocampal circuits throughout adulthood. Understanding how these cells integrate within well formed circuits will increase our knowledge about the basic principles governing circuit assembly in the adult hippocampus. This study uses a combined connectivity analysis (anatomical, functional, and effective

  15. Dynamic Response of a Grid Connected Wind Farm with Different Types of Generators

    Directory of Open Access Journals (Sweden)

    Helmy Mohammed El_ Zoghby

    2012-01-01

    Full Text Available For a wide areas wind farm, which composed of different zones of different wind turbines and different generators , this paper aims to simulate  a wind farm model that icludes  a wind turbine and three different  types of generators , which are three phase synchronous generator, three phase squirrel-cage induction generator and three phase doubly-fed induction generator ,these generators are the main machines that generally used in the field of wind energy generation.  All generators are connected in parallel at the point of common coupling (pcc  and connected to the utility grid  .  This model is a simple representation of the actual  model of  zafarana  wind farm,  which is the biggest wind farm in Egypt and further to use it in different kinds of simulations, and display the difference in response among all generators, where all generators are  500 kw power rating , and subjected to the same operating conditions . After modeling the system, the transient response of the system will be studied and analyzed at different operating cases as: Case.1 constant wind speed operation Case.2 variable wind speed operation Case.3 sudden change in turbine mechanical power Case.4 sudden change in wind speed. So this paper introduces a survey on the dynamic response of a large wind farm of different generators at different operating conditions Keywords: modeling, synchronous generator, induction generator, wind farm, simulation model, transient analysis.

  16. Realization of a high voltage generator by series connection of floating modules.

    Science.gov (United States)

    Antonini, P; Benato, A; Borsato, E; Carugno, G; Gobbo, R; Montecassiano, F; Pegoraro, M; Pesavento, G; Zago, M; Zotto, P

    2017-02-01

    A high voltage generator built by a series connection of 100 kV modules was produced. The series connection feasibility is ensured by the inherent floating character of each module which is wireless powered by high efficiency photovoltaic cells illuminated by a laser system. Each module is equipped with a control and monitoring board allowing excellent stabilization of the high voltage output. The performance of the system in terms of reliability, stability, and efficiency was evaluated. In particular using a three module setup, we achieved a maximum voltage of 234 kV with stability better than 0.1%.

  17. Change in network connectivity during fictive-gasping generation in hypoxia: Prevention by a metabolic intermediate

    Directory of Open Access Journals (Sweden)

    Andrés eNieto-Posadas

    2014-07-01

    Full Text Available The neuronal circuit in charge of generating the respiratory rhythms, localized in the pre-Bötzinger complex (preBötC, is configured to produce fictive-eupnea during normoxia and reconfigures to produce fictive-gasping during hypoxic conditions in vitro. The mechanisms involved in such reconfiguration have been extensively investigated by cell-focused studies, but the actual changes at the network level remain elusive. Since a failure to generate gasping has been linked to Sudden Infant Death Syndrome, the study of gasping generation and pharmacological approaches to promote it may have clinical relevance. Here, we study the changes in network dynamics and circuit reconfiguration that occur during the transition to fictive-gasping generation in the brainstem slice preparation by recording the preBötC with multi-electrode arrays and assessing correlated firing among respiratory neurons or clusters of respiratory neurons (multiunits. We studied whether the respiratory network reconfiguration in hypoxia involves changes in either the number of active respiratory elements, the number of functional connections among elements, or the strength of these connections. Moreover, we tested the influence of isocitrate, a Krebs cycle intermediate that has recently been shown to promote breathing, on the configuration of the preBötC circuit during normoxia and on its reconfiguration during hypoxia. We found that, in contrast to previous suggestions based on cell-focused studies, the number and the overall activity of respiratory neurons change only slightly during hypoxia. However, hypoxia induces a reduction in the strength of functional connectivity within the circuit without reducing the number of connections. Isocitrate prevented this reduction during hypoxia while increasing the strength of network connectivity. In conclusion, we provide an overview of the configuration of the respiratory network under control conditions and how it is reconfigured

  18. Identification of Synchronous Generator Electric Parameters Connected to the Distribution Grid

    Directory of Open Access Journals (Sweden)

    Frolov M. Yu.

    2017-04-01

    Full Text Available According to modern trends, the power grids with distributed generation will have an open system architecture. It means that active consumers, owners of distributed power units, including mobile units, must have free access to the grid, like when using internet, so it is necessary to have plug and play technologies. Thanks to them, the system will be able to identify the unit type and the unit parameters. Therefore, the main aim of research, described in the paper, was to develop and research a new method of electric parameters identification of synchronous generator. The main feature of the proposed method is that parameter identification is performed while the generator to the grid, so it fits in the technological process of operation of the machine and does not influence on the connection time of the machine. For the implementation of the method, it is not necessary to create dangerous operation modes for the machine or to have additional expensive equipment and it can be used for salient pole machines and round rotor machines. The parameter identification accuracy can be achieved by more accurate account of electromechanical transient process, and making of overdetermined system with many more numbers of equations. Parameter identification will be made with each generator connection to the grid. Comparing data obtained from each connection, the middle values can be find by numerical method, and thus, each subsequent identification will accurate the machine parameters.

  19. Exploring 'generative mechanisms' of the antiretroviral adherence club intervention using the realist approach: a scoping review of research-based antiretroviral treatment adherence theories.

    Science.gov (United States)

    Mukumbang, Ferdinand C; Van Belle, Sara; Marchal, Bruno; van Wyk, Brian

    2017-05-04

    Poor retention in care and non-adherence to antiretroviral therapy (ART) continue to undermine the success of HIV treatment and care programmes across the world. There is a growing recognition that multifaceted interventions - application of two or more adherence-enhancing strategies - may be useful to improve ART adherence and retention in care among people living with HIV/AIDS. Empirical evidence shows that multifaceted interventions produce better results than interventions based on a singular perspective. Nevertheless, the bundle of mechanisms by which multifaceted interventions promote ART adherence are poorly understood. In this paper, we reviewed theories on ART adherence to identify candidate/potential mechanisms by which the adherence club intervention works. We searched five electronic databases (PubMed, EBSCOhost, CINAHL, PsycARTICLES and Google Scholar) using Medical Subject Headings (MeSH) terms. A manual search of citations from the reference list of the studies identified from the electronic databases was also done. Twenty-six articles that adopted a theory-guided inquiry of antiretroviral adherence behaviour were included for the review. Eleven cognitive and behavioural theories underpinning these studies were explored. We examined each theory for possible 'generative causality' using the realist evaluation heuristic (Context-Mechanism-Outcome) configuration, then, we selected candidate mechanisms thematically. We identified three major sets of theories: Information-Motivation-Behaviour, Social Action Theory and Health Behaviour Model, which explain ART adherence. Although they show potential in explaining adherence bebahiours, they fall short in explaining exactly why and how the various elements they outline combine to explain positive or negative outcomes. Candidate mechanisms indentified were motivation, self-efficacy, perceived social support, empowerment, perceived threat, perceived benefits and perceived barriers. Although these candidate

  20. Dynamic angle stability of an industrial turbo generator connected in power system

    Science.gov (United States)

    Grouni, S.; Hallak, M.; Aibeche, A.; Ramdani, A.; Bouallegue, K.

    2014-12-01

    This paper deals with the dynamic problem of oscillation and damping on an industrial turbo generator connected to infinite networks. A set of equations that governs the turbo generator connected to infinite bus are written in characteristic form. The power system stabilizer PSS applied in order to solve the problem of damping internal angle and operating power system synchronization. The PSS model described is inspired from Heffron-Philips model is applied on real parameters simulation under Matlab simulink. The results obtained from practical application are advantageous which variations of amplitude and time mitigation oscillations magnitude of electrical and mechanical output variables. This numerical experiment permits to gain more simplicity compared with several methods applied in a real operating prototyping systems. The PSS that is used will improve the dynamic stability.

  1. Conceptual Frameworks and Practical Applications to Connect Generations in the Technoscape

    Directory of Open Access Journals (Sweden)

    Matthew Kaplan

    2015-11-01

    Full Text Available There are many ways to frame and use technology so it functions as a pathway to intergenerational engagement.  The ever evolving technoscape is filled with powerful technological tools and resources that help people connect, communicate, build relationships, and take collective action across generations.  This technology can be life-altering, especially for isolated seniors and families navigating long distance relationships.  However, at the center of the intervention equation is not the technology itself, but the quest for tapping into the relationship-enhancing potential of the technology. To explore this potential, an international survey was conducted with 46 intergenerational programs that reflect innovation and intensive uses of technology. Results demonstrate that important strides are being made in utilizing new technology for effectively connecting generations and positively affecting aging adults’ lives.

  2. Design, Digital Control, and Simulation of a Grid-Connected Photovoltaic Generation System

    OpenAIRE

    Feshara, Hazem; Elharony, Mohamed; Sharaf, Soliman

    2016-01-01

    This paper presents simulation and digital control of a three-phase grid-connected photovoltaic (PV) generation system. The technique used for maximum power point tracking (MPPT) of photovoltaic power is sliding mode (SM) control. Control of power extraction from DC link capacitor is presented. Space vector pulse width modulation (SVPWM) inverter is utilized to deliver power to utility grid. Simulation is performed using PLECS standalone software package and simulation results are shown. Comp...

  3. Performance Of Microturbine Generation System in Grid Connected and Islanding Modes of Operation

    OpenAIRE

    Gaonkar, Dattatraya N.

    2010-01-01

    The Distributed generation based on microturbine technology is new and a fast growing business. These DG systems are quickly becoming an energy management solution that saves money, resources, and environment in one compact and scalable package- be it stationary or mobile, remote or interconnected with the utility grid. In this thesis the MTG system model suitable for grid connected and islanding operation has been presented.The detailed modeling of a single-shaft MTG system suitable for grid...

  4. Research on grid connection control technology of double fed wind generator

    Science.gov (United States)

    Ling, Li

    2017-01-01

    The composition and working principle of variable speed constant frequency doubly fed wind power generation system is discussed in this thesis. On the basis of theoretical analysis and control on the modeling, the doubly fed wind power generation simulation control system is designed based on a TMS320F2407 digital signal processor (DSP), and has done a large amount of experimental research, which mainly include, variable speed constant frequency, constant pressure, Grid connected control experiment. The running results show that the design of simulation control system is reasonable and can meet the need of experimental research.

  5. RMS Current of a Photovoltaic Generator in Grid-Connected PV Systems: Definition and Application

    Directory of Open Access Journals (Sweden)

    P. J. Pérez

    2008-01-01

    Full Text Available This paper includes a definition of a new and original concept in the photovoltaic field, RMS current of a photovoltaic generator for grid-connected systems. The RMS current is very useful for calculating energy losses in cables used in a PV generator. As well, a current factor has been defined in order to simplify RMS current calculation. This factor provides an immediate (quick and easy calculation method for the RMS current that does not depend on the case particular conditions (orientation, location, etc.. RMS current and current factor values have been calculated for different locations and modules.

  6. Exploring connections between statistical mechanics and Green's functions for realistic systems. Temperature dependent entropy and internal energy from a self-consistent second-order Green's function

    CERN Document Server

    Welden, Alicia Rae; Zgid, Dominika

    2016-01-01

    Including finite-temperature effects into electronic structure calculations of semiconductors and metals is frequently necessary, but can become cumbersome using zero-temperature methods, which require an explicit evaluation of excited states to extend the approach to finite-temperature. Using a Matsubara Green's function formalism, it is easy to include the effects of temperature and to connect dynamic quantities such as the self-energy with static thermodynamic quantities such as the Helmholtz energy, entropy, and internal energy. We evaluate the thermodynamic quantities with a self-consistent Green's function where the self-energy is approximated to second-order (GF2). To validate our method, we benchmark it against finite temperature full configuration interaction (FCI) calculations for a hydrogen fluoride (HF) molecule and find excellent agreement at high temperatures and very good agreement at low temperatures. Then, we proceed to evaluate thermodynamic quantities for a one-dimension hydrogen solid at v...

  7. Impact of Rural Grid-Connected Photovoltaic Generation Systems on Power Quality

    Directory of Open Access Journals (Sweden)

    Rita Pinto

    2016-09-01

    Full Text Available Photovoltaic (PV generation systems have been increasingly used to generate electricity from renewable sources, attracting a growing interest. Recently, grid connected PV micro-generation facilities in individual homes have increased due to governmental policies as well as greater attention by industry. As low voltage (LV distribution systems were built to make energy flow in one direction, the power feed-in of PV generation in rural low-voltage grids can influence power quality (PQ as well as facility operation and reliability. This paper presents results on PQ analysis of a real PV generation facility connected to a rural low-voltage grid. Voltage fluctuations and voltage harmonic contents were observed. Statistical analysis shows a negative impact on PQ produced by this PV facility and also that only a small fraction of the energy available during a sunny day is converted, provoking losses of revenue and forcing the converter to work in an undesirable operating mode. We discuss the disturbances imposed upon the grid and their outcome regarding technical and economic viability of the PV system, as well as possible solutions. A low-voltage grid strengthening has been suggested and implemented. After that a new PQ analysis shows an improvement in the impact upon PQ, making this facility economically viable.

  8. Exploring connections between statistical mechanics and Green's functions for realistic systems: Temperature dependent electronic entropy and internal energy from a self-consistent second-order Green's function.

    Science.gov (United States)

    Welden, Alicia Rae; Rusakov, Alexander A; Zgid, Dominika

    2016-11-28

    Including finite-temperature effects from the electronic degrees of freedom in electronic structure calculations of semiconductors and metals is desired; however, in practice it remains exceedingly difficult when using zero-temperature methods, since these methods require an explicit evaluation of multiple excited states in order to account for any finite-temperature effects. Using a Matsubara Green's function formalism remains a viable alternative, since in this formalism it is easier to include thermal effects and to connect the dynamic quantities such as the self-energy with static thermodynamic quantities such as the Helmholtz energy, entropy, and internal energy. However, despite the promising properties of this formalism, little is known about the multiple solutions of the non-linear equations present in the self-consistent Matsubara formalism and only a few cases involving a full Coulomb Hamiltonian were investigated in the past. Here, to shed some light onto the iterative nature of the Green's function solutions, we self-consistently evaluate the thermodynamic quantities for a one-dimensional (1D) hydrogen solid at various interatomic separations and temperatures using the self-energy approximated to second-order (GF2). At many points in the phase diagram of this system, multiple phases such as a metal and an insulator exist, and we are able to determine the most stable phase from the analysis of Helmholtz energies. Additionally, we show the evolution of the spectrum of 1D boron nitride to demonstrate that GF2 is capable of qualitatively describing the temperature effects influencing the size of the band gap.

  9. Exploring connections between statistical mechanics and Green's functions for realistic systems: Temperature dependent electronic entropy and internal energy from a self-consistent second-order Green's function

    Science.gov (United States)

    Welden, Alicia Rae; Rusakov, Alexander A.; Zgid, Dominika

    2016-11-01

    Including finite-temperature effects from the electronic degrees of freedom in electronic structure calculations of semiconductors and metals is desired; however, in practice it remains exceedingly difficult when using zero-temperature methods, since these methods require an explicit evaluation of multiple excited states in order to account for any finite-temperature effects. Using a Matsubara Green's function formalism remains a viable alternative, since in this formalism it is easier to include thermal effects and to connect the dynamic quantities such as the self-energy with static thermodynamic quantities such as the Helmholtz energy, entropy, and internal energy. However, despite the promising properties of this formalism, little is known about the multiple solutions of the non-linear equations present in the self-consistent Matsubara formalism and only a few cases involving a full Coulomb Hamiltonian were investigated in the past. Here, to shed some light onto the iterative nature of the Green's function solutions, we self-consistently evaluate the thermodynamic quantities for a one-dimensional (1D) hydrogen solid at various interatomic separations and temperatures using the self-energy approximated to second-order (GF2). At many points in the phase diagram of this system, multiple phases such as a metal and an insulator exist, and we are able to determine the most stable phase from the analysis of Helmholtz energies. Additionally, we show the evolution of the spectrum of 1D boron nitride to demonstrate that GF2 is capable of qualitatively describing the temperature effects influencing the size of the band gap.

  10. Reliability Oriented Design Tool For the New Generation of Grid Connected PV-Inverters

    DEFF Research Database (Denmark)

    Sintamarean, Nicolae Cristian; Blaabjerg, Frede; Wang, Huai

    2015-01-01

    This paper introduces a reliability-oriented design tool for a new generation of grid-connected photovoltaic (PV) inverters. The proposed design tool consists of a real field mission profile (RFMP) model (for two operating regions: USA and Denmark), a PV panel model, a grid-connected PV inverter...... model, an electrothermal model, and the lifetime model of the power semiconductor devices. An accurate long-term simulation model able to consider the one-year RFMP (solar irradiance and ambient temperature) is developed. Thus, the one-year estimation of the converter device thermal loading distribution...... is achieved and is further used as an input to the lifetime model. The proposed reliability-oriented design tool is used to study the impact of mission profile (MP) variation and device degradation (aging) in the PV inverter lifetime. The obtained results indicate that the MP of the field where the PV...

  11. Modified Grid-Connected CSI for Hybrid PV/Wind Power Generation System

    Directory of Open Access Journals (Sweden)

    D. Amorndechaphon

    2012-01-01

    Full Text Available The principle of a power conditioning unit for hybrid PV/wind power generation system is proposed. The proposed power conditioner is based on the current source inverter (CSI topology. All energy sources are connected in parallel with a DC-bus through the modified wave-shaping circuits. To achieve the unity power factor at the utility grid, the DC-link current can be controlled via the wave-shaping circuits with the sinusoidal PWM scheme. In this work, the carrier-based PWM scheme is also proposed to minimize the utility current THD. The power rating of the proposed system can be increased by connecting more PV/wind modules through their wave-shaping circuits in parallel with the other modules. The details of the operating principles, the system configurations, and the design considerations are described. The effectiveness of the proposed CSI is demonstrated by simulation results.

  12. Optimum siting and sizing of a large distributed generator in a mesh connected system

    Energy Technology Data Exchange (ETDEWEB)

    Elnashar, Mohab M.; El Shatshat, Ramadan; Salama, Magdy M.A. [Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, Ontario (Canada)

    2010-06-15

    This paper proposes a new approach to optimally determine the appropriate size and location of the distributed generator (DG) in a large mesh connected system. This paper presents a visual optimization approach in which the planner plays an important role in determining the optimal siting and sizing of the DG through the choice of the appropriate weight factors of the parameters included in the optimization technique according to the system deficiencies. Losses, voltage profile and short circuit level are used in the algorithm to determine the optimum sizes and locations of the DG. The short circuit level parameter is introduced to represent the protective device requirements in the selection of the size and location of the DG. The proposed technique has been tested on the IEEE 24 - bus mesh connected test system. The obtained results showed clearly that the optimal size and location can be simply determined through the proposed approach. (author)

  13. Analysis and estimation of transient stability for a grid-connected wind turbine with induction generator

    Energy Technology Data Exchange (ETDEWEB)

    Li, H.; Yang, C.; Chen, H.W. [The State Key Laboratory of Equipment and System Safety of Power Transmission and Distribution and New Technology, Electrical Engineering College of Chongqing University, Chongqing 400044 (China); Zhao, B. [The State Key Laboratory of Equipment and System Safety of Power Transmission and Distribution and New Technology, Electrical Engineering College of Chongqing University, Chongqing 400044 (China); Sichuan Electric Vocational and Technical College, Chengdu 610072 (China); Chen, Z. [Institute of Energy Technology, Aalborg University, Aalborg East DK-9220 (Denmark)

    2011-05-15

    Increasing levels of wind energy in modern electrical power system is initiating a need for accurate analysis and estimation of transient stability of wind turbine generation systems. This paper investigates the transient behaviors and possible direct methods for transient stability evaluation of a grid-connected wind turbine with squirrel cage induction generator (SCIG). Firstly, by using an equivalent lump mass method, a three-mass wind turbine equivalent model is proposed considering both the blades and the shaft flexibility of the wind turbine drive train system. Combined with the detailed electromagnetic transient models of a SCIG, the transient behaviors of the wind turbine generation system during a three-phase fault are simulated and compared with the traditional models. Secondly, in order to quickly estimate the transient stability limit of the wind turbine generation system, a direct method based on normal form theory is proposed. The transient models of the wind turbine generation system including the flexible drive train model are derived based on the direct transient stability estimation method. A method of critical clearing time (CCT) calculation is developed for the transient stability estimation of the wind turbine generation system. Finally, the CCT at various initial mechanical torques for different dynamical models are calculated and compared with the trial and error method by simulation, when the SCIG stator terminal is subjected to a three-phase short-circuit fault. The results have shown the proposed method and models are correct and valid. (author)

  14. Dual generators of the fundamental group and the moduli space of flat connections

    CERN Document Server

    Meusburger, C

    2006-01-01

    We define the dual of a set of generators of the fundamental group of an oriented two-surface $S_{g,n}$ of genus $g$ with $n$ punctures and the associated surface $S_{g,n}\\setminus D$ with a disc $D$ removed. This dual is another set of generators related to the original generators via an involution and has the properties of a dual graph. In particular, it provides an algebraic prescription for determining the intersection points of a curve representing a general element of the fundamental group $\\pi_1(S_{g,n}\\setminus D)$ with the representatives of the generators and the order in which these intersection points occur on the generators.We apply this dual to the moduli space of flat connections on $S_{g,n}$ and show that when expressed in terms both, the holonomies along a set of generators and their duals, the Poisson structure on the moduli space takes a particularly simple form. Using this description of the Poisson structure, we derive explicit expressions for the Poisson brackets of general Wilson loop o...

  15. Control and Modulation Techniques for a Centralized PV Generation System Grid Connected via an Interleaved Inverter

    Directory of Open Access Journals (Sweden)

    Gianluca Brando

    2016-09-01

    Full Text Available In the context of grid connected photovoitaic (PV generation systems, there are two paramount aspects regarding the Maximum Power Point Tracking (MPPT of the photovoltaic units and the continuity of the service. The most diffused MPPT algorithms are based on either perturb and observe, or on an incremental conductance approach and need both PV current and voltage measurements. Several topology reconfigurable converters are also associated with the PV plants, guaranteeing fault-tolerant features. The generation continuity can also be assured by interleaved inverters, which keep the system operating at reduced maximum power in case of failure. In this paper, an evolution of a hysteresis based MPPT algorithm is presented, based on the measurement of only one voltage, together with a novel space vector modulation suitable for a two-channel three-phase grid connected interleaved inverter. The proposed MMPT algorithm and modulation technique are tested by means of several numerical analyses on a PV generation system of about 200 kW maximum power. The results testify the validity of the proposed strategies, showing good performance, even during a fault occurrence and in the presence of deep shading conditions.

  16. Artificial Bee Colony Algorithm for Transient Performance Augmentation of Grid Connected Distributed Generation

    Science.gov (United States)

    Chatterjee, A.; Ghoshal, S. P.; Mukherjee, V.

    In this paper, a conventional thermal power system equipped with automatic voltage regulator, IEEE type dual input power system stabilizer (PSS) PSS3B and integral controlled automatic generation control loop is considered. A distributed generation (DG) system consisting of aqua electrolyzer, photovoltaic cells, diesel engine generator, and some other energy storage devices like flywheel energy storage system and battery energy storage system is modeled. This hybrid distributed system is connected to the grid. While integrating this DG with the onventional thermal power system, improved transient performance is noticed. Further improvement in the transient performance of this grid connected DG is observed with the usage of superconducting magnetic energy storage device. The different tunable parameters of the proposed hybrid power system model are optimized by artificial bee colony (ABC) algorithm. The optimal solutions offered by the ABC algorithm are compared with those offered by genetic algorithm (GA). It is also revealed that the optimizing performance of the ABC is better than the GA for this specific application.

  17. Realistic simulation of the emergence of magnetic field generated in a solar convective dynamo from the convection zone into the corona

    Science.gov (United States)

    Chen, Feng; Rempel, Matthias D.; Fan, Yuhong

    2017-08-01

    We present a comprehensive realistic numerical model of emergence of magnetic flux generated in a solar convective dynamo from the convection zone to the corona. The magnetic and velocity fields in a horizontal layer near the top boundary of the solar convective dynamo simulation are used as a time-dependent bottom boundary to drive the radiation magnetohydrodynamic simulations of the emergence of the flux bundles through the upper most convection zone to more than 100 Mm above the surface of the Sun. The simualtion allows a direct comparison bewtween model synthesized observable and real obervations of flux emergence processes through different layers of the solar atmopshere.Emerging flux bundles bring more than 1e23 Mx flux to the photosphere in a period of about 50 hours and give rise to several active regions in a horizontal domain of 200 Mm. The mean corona temperature is about 1 MK for the quiet Sun and is significantly increased after active regions form at the photosphere. The flux emergence process produces a lot of dynamical features, such as coronal bright points, jets, waves and propagating disturbances, as well as flares and mass ejections. The biggest flare reaches M2.5 as indicated by synthetic GOES-15 soft X-ray flux. The total magnetic energy released during the eruption is about 5e31 ergs. The flare leads to a significant corona heating. The mean temperature in the coronal reaches more than 5 MK. And plasma in cusp-shaped post-flare loops is heated to several tens MK. The flare is accompanied by the ejection of a giant flux rope that carries cool and dense plasma. The flux rope is formed during the eruption by the reconnection between a sheared arcade that rises up from the low atmosphere above a bipolar sunspot pair and overlying fieldlines that are mostly perpendicular to the axis of the sheared arcade.

  18. Models for the transient stability of conventional power generating stations connected to low inertia systems

    Science.gov (United States)

    Zarifakis, Marios; Coffey, William T.; Kalmykov, Yuri P.; Titov, Sergei V.

    2017-06-01

    An ever-increasing requirement to integrate greater amounts of electrical energy from renewable sources especially from wind turbines and solar photo-voltaic installations exists and recent experience in the island of Ireland demonstrates that this requirement influences the behaviour of conventional generating stations. One observation is the change in the electrical power output of synchronous generators following a transient disturbance especially their oscillatory behaviour accompanied by similar oscillatory behaviour of the grid frequency, both becoming more pronounced with reducing grid inertia. This behaviour cannot be reproduced with existing mathematical models indicating that an understanding of the behaviour of synchronous generators, subjected to various disturbances especially in a system with low inertia requires a new modelling technique. Thus two models of a generating station based on a double pendulum described by a system of coupled nonlinear differential equations and suitable for analysis of its stability corresponding to infinite or finite grid inertia are presented. Formal analytic solutions of the equations of motion are given and compared with numerical solutions. In particular the new finite grid model will allow one to identify limitations to the operational range of the synchronous generators used in conventional power generation and also to identify limits, such as the allowable Rate of Change of Frequency which is currently set to ± 0.5 Hz/s and is a major factor in describing the volatility of a grid as well as identifying requirements to the total inertia necessary, which is currently provided by conventional power generators only, thus allowing one to maximise the usage of grid connected non-synchronous generators, e.g., wind turbines and solar photo-voltaic installations.

  19. The effects of realistic synaptic distribution and 3D geometry on signal integration and extracellular field generation of hippocampal pyramidal cells and inhibitory neurons

    Directory of Open Access Journals (Sweden)

    Attila I Gulyas

    2016-11-01

    Full Text Available In vivo and in vitro multichannel field and somatic intracellular recordings are frequently used to study mechanisms of network pattern generation. When interpreting these data, neurons are often implicitly considered as electrotonically compact cylinders with a homogeneous distribution of excitatory and inhibitory inputs. However, the actual distributions of dendritic length, diameter, and the densities of excitatory and inhibitory input are non-uniform and cell type-specific. We first review quantitative data on the dendritic structure and synaptic input and output distribution of pyramidal cells and interneurons in the hippocampal CA1 area. Second, using multicompartmental passive models of four different types of neurons, we quantitatively explore the effect of differences in dendritic structure and synaptic distribution on the errors and biases of voltage clamp measurements of inhibitory and excitatory postsynaptic currents. Finally, using the 3-dimensional distribution of dendrites and synaptic inputs we calculate how different inhibitory and excitatory inputs contribute to the generation of local field potential in the hippocampus. We analyze these effects at different realistic background activity levels as synaptic bombardment influences neuronal conductance and thus the propagation of signals in the dendritic tree.We conclude that, since dendrites are electrotonically long and entangled in 3D, somatic intracellular and field potential recordings miss the majority of dendritic events in some cell types, and thus overemphasize the importance of perisomatic inhibitory inputs and belittle the importance of complex dendritic processing. Modeling results also suggest that pyramidal cells and inhibitory neurons probably use different input integration strategies. In pyramidal cells, second- and higher-order thin dendrites are relatively well-isolated from each other, which may support branch-specific local processing as suggested by studies

  20. Design and Modeling of Grid Connected Hybrid Renewable Energy Power Generation

    Directory of Open Access Journals (Sweden)

    M. Kishore Reddy,

    2014-09-01

    Full Text Available This paper proposes a design and modeling of grid connected hybrid renewable energy power generation. The energy system having a photo voltaic (PV panel, Srg wind turbine and fuel cell (sofc for continuous power flow management. Fuel cells (storage & generating are added to ensure uninterrupted power supply due to the discontinuous nature of solar and wind resources. Renewable energy generated during times of plenty can be stored for use during periods when sufficient electricity is not available. But storing this energy is a difficult task: batteries and similar technologies perform well over short timescales, but over periods of weeks or months a different approach is necessary. Energy storage in the form of hydrogen is one such possibility: excess electricity is fed into an electrolyser to split water into its constituent parts, oxygen and hydrogen. The hydrogen is then used in fuel cells to produce electricity when needed which will overcome the problem of storage. This work is mainly concentrated on the design, analysis and modelling of Fuel cells and Analysis and modelling of Switched Reluctance Generator (SRG in the application of Wind Energy Generation and pv cell. Also an effective approach is proposed in this thesis to ensure renewable energy diversity and effective utilization. The pv cell, wind and fuel cell renewable energy system is digitally simulated using the MATLAB/SIMULINK software environment and fully validated for efficient energy utilizations and enhanced interface power quality under different operating conditions and load excursions

  1. 3D reconstruction method and connectivity rules of fracture networks generated under different mining layouts

    Institute of Scientific and Technical Information of China (English)

    Zhang Ru; Ai Ting; Li Hegui; Zhang Zetian; Liu Jianfeng

    2013-01-01

    In current research, a series of triaxial tests, which were employed to simulate three typical mining lay-outs (i.e., top-coal caving, non-pillar mining and protected coal seam mining), were conducted on coal by using MTS815 Flex Test GT rock mechanics test system, and the fracture networks in the broken coal samples were qualitatively and quantitatively investigated by employing CT scanning and 3D reconstruc-tion techniques. This work aimed at providing a detail description on the micro-structure and fracture-connectivity characteristics of rupture coal samples under different mining layouts. The results show that: (i) for protected coal seam mining layout, the coal specimens failure is in a compression-shear manner and oppositely, (ii) the tension-shear failure phenomenon is observed for top-coal caving and non-pillar mining layouts. By investigating the connectivity features of the generated fractures in the direction of r1 under different mining layouts, it is found that the connectivity level of the fractures of the samples corresponding to non-pillar mining layout was the highest.

  2. A Determination Method of the Restoration Configuration Considering Many Connections of Distributed Generators

    Science.gov (United States)

    Takano, Hirotaka; Hayashi, Yasuhiro; Matsuki, Junya; Sugaya, Shuhei

    In the field of electrical power system, various approaches, such as utilization of renewable energy, loss reduction, and so on, have been taken to reduce CO2 emission. So as to work toward this goal, the total number of distributed generators (DGs) using renewable energy connected into 6.6kV distribution system has been increasing rapidly. However, when a fault occurs such as distribution line faults and bank faults, DGs connecting outage sections are disconnected simultaneously. Since the output of DGs influences feeder current and node voltage of distribution system, it is necessary to determine the optimal system configuration considering simultaneous disconnection and reconnection of DGs. In this paper, the authors propose a computation method to determine the optimal restoration configuration considering many connections of DGs. The feature of determined restoration configurations is prevention of the violation of operational constraints by disconnection and reconnection of DGs. Numerical simulations are carried out for a real scale distribution system model with 4 distribution substations, 72 distribution feeders, 252 sectionalizing switches (configuration candidates are 2252) and 23.2MW DGs (which is 14% of total load) in order to examine the validity of the proposed algorithm.

  3. Integration of a finite element generator model into a simulated HVDC connected system

    Energy Technology Data Exchange (ETDEWEB)

    Preston, T.W.; Sturgess, J.P. [GEC Alsthom Engineering Research Center, Stafford (United Kingdom)

    1994-12-31

    Within most system analysis programs generators and motors are represented by an equivalent circuit model either a 2-axis model for both stators and rotor or a three-phase model of the stator and a two-axis model of the rotor. This may be adequate under certain operating conditions such as steady-state or some symmetrical faults but for inverter-fed motors or generators feeding into a rectified load a more rigorous model of the machine is required. This paper describes the theory and development of such a model, its integration with the power electronics and application to 6-pulse and 12-pulse converters, the latter being appropriate in systems similar to HVDC unit connection. (author) 5 refs., 16 figs.

  4. Thermoelectric generator sandwiched in a crossflow heat exchanger with optimal connectivity between modules

    Energy Technology Data Exchange (ETDEWEB)

    Belanger, Simon [Departement de genie mecanique, Universite Laval, 1065, avenue de la Medecine, Quebec City, QC, G1V 0A6 (Canada); Gosselin, Louis, E-mail: Louis.Gosselin@gmc.ulaval.ca [Departement de genie mecanique, Universite Laval, 1065, avenue de la Medecine, Quebec City, QC, G1V 0A6 (Canada)

    2011-08-15

    Highlights: {yields} In this paper, we propose a numerical model for a crossflow heat exchanger with a thermoelectric generator sandwiched in its wall. {yields} The number of thermoelectric modules and the electrical connections between them is optimized with a genetic algorithm. {yields} Complex electric current topologies are achieved in order to maximize the total power output. - Abstract: The design of a thermoelectric generator sandwiched in the wall of a crossflow heat exchanger was optimized. A numerical model has been developed and validated. The objective function was the total power output. The design variables were the number of modules and the current in each control volume of the mesh. We also optimize directly the electrical topology of the system. A genetic algorithm was used to perform the optimizations. Complex optimal electrical topologies were achieved due to the non-uniform temperatures distributions in the heat exchanger.

  5. A generative modeling approach to connectivity-Electrical conduction in vascular networks

    DEFF Research Database (Denmark)

    Hald, Bjørn Olav

    2016-01-01

    The physiology of biological structures is inherently dynamic and emerges from the interaction and assembly of large collections of small entities. The extent of coupled entities complicates modeling and increases computational load. Here, microvascular networks are used to present a novel...... generative approach to connectivity based on the observation that biological organization is hierarchical and composed of a limited set of building blocks, i.e. a vascular network consists of blood vessels which in turn are composed by one or more cell types. Fast electrical communication is crucial...... sophisticated models of vascular dynamics, the generative approach can be applied to other biological systems, e.g. nervous tissue, the lymphatics, or the biliary system....

  6. Experimental Section: On the magnetic field distribution generated by a dipolar current source situated in a realistically shaped compartment model of the head

    NARCIS (Netherlands)

    Meijs, J.W.H.; Bosch, F.G.C.; Peters, M.J.; Lopes da silva, F.H.

    1987-01-01

    The magnetic field distribution around the head is simulated using a realistically shaped compartment model of the head. The model is based on magnetic resonance images. The 3 compartments describe the brain, the skull and the scalp. The source is represented by a current dipole situated in the

  7. What is the primary driver of downstream connectivity: runoff generation, storage or conveyance?

    Science.gov (United States)

    Ali, G.; Elliott, J.; Lobb, D.; Yarotski, J.

    2013-12-01

    Understanding how headwater streams are connected to downstream areas through the generation and delivery of stream discharge is critical for process conceptualization and hydrological modelling. Several factors have been shown to influence downstream connectivity (DC), notably the location of runoff-generating areas, the mitigating effect of surface depressional storage areas on the delivery of runoff to streams, and the effectiveness of diffuse and concentrated flow paths as runoff conveyance features. Limited efforts have been made to rank these factors in order of importance. Here we aimed to identify the relative influence of runoff generation, storage and conveyance factors on DC in an agricultural Prairie watershed. The 75 km2 South Tobacco Creek Watershed (STCW, south-central Manitoba, Canada) is drained by a 20 km-long creek that drops nearly 200 m in elevation over its course; it is characterized by highly seasonal dynamics such as sheet flow on frozen ground in spring, intermittent flow in summer, and significant surface and subsurface flow events in fall. Hourly discharge records were obtained for seven pairs of upstream-downstream gauging stations within the STCW: for each pair, the magnitude of DC was estimated using cross-correlation values of the two discharge timeseries, while the timing of DC was characterized using cross-correlation lags (in hours or days) to assess the delay of peak flows between upstream and downstream stations. LiDAR data was also used to extract topographic information on: i) the location of runoff-generating areas (i.e., upper-, mid-, low- slope and riparian areas), ii) the area and depth of surface depressional storage basins, and iii) the total length of flow conveyance features (defined streams, all flow paths) in the incremental catchment area between upstream and downstream gauging stations. The computed discharge cross-correlation values indicate that the magnitude of DC is highest in spring, followed by fall then

  8. FACTS Devices Using Neuro Fuzzy Controller in Stabilization of Grid Connected Wind Generator.

    Directory of Open Access Journals (Sweden)

    ROHI KACHROO

    2012-05-01

    Full Text Available Wind power is one of the renewable energy sources. It has various advantages like, cost competitiveness, environmentally clean and safeness. Large wind farms have stability problems when they are integrated to the power system. A thorough analysis is required to identify the stability problems and to develop measures to improve it. Mostly used wind generator is a fixed speed induction generator, which requires reactive power to maintain air gap flux. Reactive ower equipments are used to enable recovery of large wind farms from severe system disturbances. In this paper shunt and series FACTS evices, Static Synchronous Compensator (STATCOM and Static ynchronous Series Compensator are used for the purpose of stabilizing grid connected wind generator against the grid-side disturbances. The essential feature of the FACTS devices is their ability to absorb or inject the reactive power. Since stability is a non linear process so system performance can be improved by using nonlinear controllers. Neurofuzzy controller (NFC is a non linear controller. NFC has fasterresponse than conventional PI controllers

  9. Performance of a grid-connected wind generation system with a robust susceptance controller

    Energy Technology Data Exchange (ETDEWEB)

    Rahim, A.H.M.A. [Department of Electrical Engineering, K.F. University of Petroleum and Minerals, KFUPM Box 349, Dhahran 31261 (Saudi Arabia); Nowicki, E.P. [Department of Electrical and Computer Engineering, University of Calgary, Calgary, AB (Canada)

    2011-01-15

    Wind turbine driven induction generators are vulnerable to transient disturbances like wind gusts and low voltages on the system. The fixed capacitor at the generator terminal or the limited support from the grid may not be able to provide the requisite reactive power under these abnormal conditions. This paper presents a susceptance control strategy for a variable speed wound-rotor induction generator which can cater for the reactive power requirement. The susceptance is adjusted through a robust feedback controller included in the terminal voltage driven automatic excitation control circuit. The fixed parameter robust controller design is carried out in frequency domain using multiplicative uncertainty modeling and H{sub {infinity}} norms. The robustness of the controller has been evaluated through optimally tuned PID controllers. Simulation results show that the robust controller can effectively restore normal operation following emergencies like sudden load changes, wind gusts and low voltage conditions. The proposed robust controller has been shown to have adequate fault ride through capabilities in order to be able to meet connection requirements defined by transmission system operators. (author)

  10. Voltage dip generator for testing wind turbines connected to electrical networks

    Energy Technology Data Exchange (ETDEWEB)

    Veganzones, C.; Martinez, S.; Platero, C.A.; Blazquez, F.; Ramirez, D.; Arribas, J.R.; Merino, J.; Gordillo, F. [Department of Electrical Engineering, ETSII, Universidad Politecnica de Madrid, C/Jose Gutierrez Abascal 2, 28006 Madrid (Spain); Sanchez, J.A.; Herrero, N. [Department of Civil Engineering, Hydraulics and Energy, ETSICCP, Universidad Politecnica de Madrid, Ciudad Universitaria, s/n. 28040 Madrid (Spain)

    2011-05-15

    This paper describes a new voltage dip generator that allows the shape of the time profile of the voltage generated to be configured. The use of this device as a tool to test the fault ride-through capability of wind turbines connected to the electricity grid can provide some remarkable benefits: First, this system offers the possibility of adapting the main features of the time-voltage profile generated (dip depth, dip duration, the ramp slope during the recovery process after clearing fault, etc.) to the specific requirements set forth by the grid operation codes, in accordance with different network electrical systems standards. Second, another remarkable ability of this system is to provide sinusoidal voltage and current wave forms during the overall testing process without the presence of harmonic components. This is made possible by the absence of electronic converters. Finally, the paper includes results and a discussion on the experimental data obtained with the use of a reduced size laboratory prototype that was constructed to validate the operating features of this new device. (author)

  11. Overview of Power Generation Sector of Bangladesh and Proposed Grid Connected Hybrid Renewable Energy System

    Directory of Open Access Journals (Sweden)

    Md. Raju Ahmed

    2014-11-01

    Full Text Available Electricity is the most usable form of energy, and one of the most crucial strategic issues for the sustainable development of a country. The projection of demand of electricity is an integral part of the planning process. Severe power crisis compelled the government to enter into contractual agreements for high-cost temporary solution such as rental power and small IPPS, on an emergency basis, most of these are diesel or liquid-fuel based. Load shading is an acute problem for the country. The country is confronting a simultaneous shortage of electricity. However, the country has substantial amount of renewable energy resources. The overview of power generation section of Bangladesh is presented; the potentiality of renewable energy sources in Bangladesh is discussed. Finally, a grid connected hybrid renewable energy system is proposed to overcome the problem of power crisis using sustainable clean energy at rural area.

  12. Optimal DG Source Allocation for Grid Connected Distributed Generation with Energy Storage System

    Directory of Open Access Journals (Sweden)

    S. Ezhilarasan

    2015-05-01

    Full Text Available This study proposes an Energy Management System (EMS for allocation of DG source in a grid connected hybrid power system. Modeling and simulation for EMS is implemented using MATLAB/SIMULINK package. The objective of proposed EMS for micro grid is to optimize the fuel cost, improving the energy utilization efficiency and to manage the peak load demand by scheduling the generation according to the availability of the fuel. The proposed intelligent energy management system is designed to optimize the availability of energy to the load according to the level of priority and to manage the power flow. The developed management system performance was assessed using a hybrid system having PV panels, Wind Turbine (WT, battery and biomass gasifier. Real time field test has been conducted and the parameters i.e., solar irradiance, temperature, wind speed are gathered from 4.05 KW off grid and 2.0 KW On grid Solar Photovoltaic systems (SPV system and wind turbine. The dynamic behavior of the proposed model is examined under different operating conditions. The simulation results of proposed EMS using fuzzy logic expert system shows the minimization on the operating cost and emission level of micro grid by optimal scheduling of power generation and maintains the State of Charge (SOC of batteries in desired value which improves the battery life. The proposed multi objective intelligent energy management system aims to minimize the operational cost and the environmental impact of a micro grid.

  13. Voltage Control Scheme with Distributed Generation and Grid Connected Converter in a DC Microgrid

    Directory of Open Access Journals (Sweden)

    Jong-Chan Choi

    2014-10-01

    Full Text Available Direct Current (DC microgrids are expected to become larger due to the rapid growth of DC energy sources and power loads. As the scale of the system expends, the importance of voltage control will be increased to operate power systems stably. Many studies have been performed on voltage control methods in a DC microgrid, but most of them focused only on a small scale microgrid, such as a building microgrid. Therefore, a new control method is needed for a middle or large scale DC microgrid. This paper analyzes voltage drop problems in a large DC microgrid and proposes a cooperative voltage control scheme with a distributed generator (DG and a grid connected converter (GCC. For the voltage control with DGs, their location and capacity should be considered for economic operation in the systems. Accordingly, an optimal DG allocation algorithm is proposed to minimize the capacity of a DG for voltage control in DC microgrids. The proposed methods are verified with typical load types by a simulation using MATLAB and PSCAD/EMTDC.

  14. Benchmarking of Constant Power Generation Strategies for Single-Phase Grid-Connected Photovoltaic Systems

    DEFF Research Database (Denmark)

    Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede

    2018-01-01

    strategies based on: 1) a power control method (P-CPG), 2) a current limit method (I-CPG) and 3) the Perturb and Observe algorithm (P&O-CPG). However, the operational mode changes (e.g., from the maximum power point tracking to a CPG operation) will affect the entire system performance. Thus, a benchmarking...... of the presented CPG strategies is also conducted on a 3-kW single-phase grid-connected PV system. Comparisons reveal that either the P-CPG or I-CPG strategies can achieve fast dynamics and satisfactory steady-state performance. In contrast, the P&O-CPG algorithm is the most suitable solution in terms of high...... active power control methods are required. As a cost-effective solution to avoid overloading, a Constant Power Generation (CPG) control scheme by limiting the feed-in power has been introduced into the currently active grid regulations. In order to achieve a CPG operation, this paper presents three CPG...

  15. Benchmarking of Constant Power Generation Strategies for Single-Phase Grid-Connected Photovoltaic Systems

    DEFF Research Database (Denmark)

    Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede

    2016-01-01

    strategies based on: 1) a power control (P-CPG), 2) a current limit method (I-CPG) and 3) the Perturb and Observe algorithm (P&O-CPG). However, the operational mode changes (e.g., from the maximum power point tracking to a CPG operation) will affect the entire system performance. Thus, a benchmarking...... of the proposed CPG strategies is also conducted on a 3-kW single-phase grid-connected PV system. Comparisons reveal that either the P-CPG or I-CPG strategies can achieve fast dynamics and satisfactory steady-state performance. In contrast, the P&OCPG algorithm is the most suitable solution in terms of high...... active power control methods are required. As a cost-effective solution to avoid overloading, a Constant Power Generation (CPG) control scheme by limiting the feed-in power has been introduced into the currently active grid regulations. In order to achieve a CPG operation, this paper proposes three CPG...

  16. Modal analysis of a grid-connected direct-drive permanent magnet synchronous generator wind turbine system

    DEFF Research Database (Denmark)

    Tan, Jin; Wang, Xiao Ru; Chen, Zhe

    2013-01-01

    In order to study the stability of a grid-connected direct-drive permanent magnet synchronous generator (PMSG) wind turbine systems, this paper presents the modal analysis of a PMSG wind turbine system. A PMSG model suitable for small signal stability analysis is presented. The modal properties o...

  17. Pedagogy for the Connected Science Classroom: Computer Supported Collaborative Science and the Next Generation Science Standards

    Science.gov (United States)

    Foley, Brian J.; Reveles, John M.

    2014-01-01

    The prevalence of computers in the classroom is compelling teachers to develop new instructional skills. This paper provides a theoretical perspective on an innovative pedagogical approach to science teaching that takes advantage of technology to create a connected classroom. In the connected classroom, students collaborate and share ideas in…

  18. Renewable Energy Jobs. Status, prospects and policies. Biofuels and grid-connected electricity generation

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, H.; Ferroukhi, R. [et al.] [IRENA Policy Advisory Services and Capacity Building Directorate, Abu Dhabi (United Arab Emirates)

    2012-01-15

    Over the past years, interest has grown in the potential for the renewable energy industry to create jobs. Governments are seeking win-win solutions to the dual challenge of high unemployment and climate change. By 2010, USD 51 billion had been pledged to renewables in stimulus packages, and by early 2011 there were 119 countries with some kind of policy target and/or support policy for renewable energy, such as feed-in tariffs, quota obligations, favourable tax treatment and public loans or grants, many of which explicitly target job creation as a policy goal. Policy-makers in many countries are now designing renewable energy policies that aim to create new jobs, build industries and benefit particular geographic areas. But how much do we know for certain about the job creation potential for renewable energy? This working paper aims to provide an overview of current knowledge on five questions: (1) How can jobs in renewable energy be characterised?; (2) How are they shared out across the technology value chain and what skill levels are required?; (3) How many jobs currently exist and where are they in the world?; (4) How many renewable energy jobs could there be in the future?; and (5) What policy frameworks can be used to promote employment benefits from renewable energy? This paper focuses on grid-connected electricity generation technologies and biofuels. Since the employment potential of off-grid applications is large, it will be covered by a forthcoming study by IRENA on job creation in the context of energy access, based on a number of case studies.

  19. Automatic generation of smart earthquake-resistant building system: Hybrid system of base-isolation and building-connection.

    Science.gov (United States)

    Kasagi, M; Fujita, K; Tsuji, M; Takewaki, I

    2016-02-01

    A base-isolated building may sometimes exhibit an undesirable large response to a long-duration, long-period earthquake ground motion and a connected building system without base-isolation may show a large response to a near-fault (rather high-frequency) earthquake ground motion. To overcome both deficiencies, a new hybrid control system of base-isolation and building-connection is proposed and investigated. In this new hybrid building system, a base-isolated building is connected to a stiffer free wall with oil dampers. It has been demonstrated in a preliminary research that the proposed hybrid system is effective both for near-fault (rather high-frequency) and long-duration, long-period earthquake ground motions and has sufficient redundancy and robustness for a broad range of earthquake ground motions.An automatic generation algorithm of this kind of smart structures of base-isolation and building-connection hybrid systems is presented in this paper. It is shown that, while the proposed algorithm does not work well in a building without the connecting-damper system, it works well in the proposed smart hybrid system with the connecting damper system.

  20. Automatic generation of smart earthquake-resistant building system: Hybrid system of base-isolation and building-connection

    Directory of Open Access Journals (Sweden)

    M. Kasagi

    2016-02-01

    Full Text Available A base-isolated building may sometimes exhibit an undesirable large response to a long-duration, long-period earthquake ground motion and a connected building system without base-isolation may show a large response to a near-fault (rather high-frequency earthquake ground motion. To overcome both deficiencies, a new hybrid control system of base-isolation and building-connection is proposed and investigated. In this new hybrid building system, a base-isolated building is connected to a stiffer free wall with oil dampers. It has been demonstrated in a preliminary research that the proposed hybrid system is effective both for near-fault (rather high-frequency and long-duration, long-period earthquake ground motions and has sufficient redundancy and robustness for a broad range of earthquake ground motions.An automatic generation algorithm of this kind of smart structures of base-isolation and building-connection hybrid systems is presented in this paper. It is shown that, while the proposed algorithm does not work well in a building without the connecting-damper system, it works well in the proposed smart hybrid system with the connecting damper system.

  1. Evaluation of local electric fields generated by transcranial direct current stimulation with an extracephalic reference electrode based on realistic 3D body modeling

    Science.gov (United States)

    Im, Chang-Hwan; Park, Ji-Hye; Shim, Miseon; Chang, Won Hyuk; Kim, Yun-Hee

    2012-04-01

    In this study, local electric field distributions generated by transcranial direct current stimulation (tDCS) with an extracephalic reference electrode were evaluated to address extracephalic tDCS safety issues. To this aim, we generated a numerical model of an adult male human upper body and applied the 3D finite element method to electric current conduction analysis. In our simulations, the active electrode was placed over the left primary motor cortex (M1) and the reference electrode was placed at six different locations: over the right temporal lobe, on the right supraorbital region, on the right deltoid, on the left deltoid, under the chin, and on the right buccinator muscle. The maximum current density and electric field intensity values in the brainstem generated by the extracephalic reference electrodes were comparable to, or even less than, those generated by the cephalic reference electrodes. These results suggest that extracephalic reference electrodes do not lead to unwanted modulation of the brainstem cardio-respiratory and autonomic centers, as indicated by recent experimental studies. The volume energy density was concentrated at the neck area by the use of deltoid reference electrodes, but was still smaller than that around the active electrode locations. In addition, the distributions of elicited cortical electric fields demonstrated that the use of extracephalic reference electrodes might allow for the robust prediction of cortical modulations with little dependence on the reference electrode locations.

  2. The Importance of Lateral Connections in the Parietal Cortex for Generating Motor Plans.

    Directory of Open Access Journals (Sweden)

    Derrik E Asher

    Full Text Available Substantial evidence has highlighted the significant role of associative brain areas, such as the posterior parietal cortex (PPC in transforming multimodal sensory information into motor plans. However, little is known about how different sensory information, which can have different delays or be absent, combines to produce a motor plan, such as executing a reaching movement. To address these issues, we constructed four biologically plausible network architectures to simulate PPC: 1 feedforward from sensory input to the PPC to a motor output area, 2 feedforward with the addition of an efference copy from the motor area, 3 feedforward with the addition of lateral or recurrent connectivity across PPC neurons, and 4 feedforward plus efference copy, and lateral connections. Using an evolutionary strategy, the connectivity of these network architectures was evolved to execute visually guided movements, where the target stimulus provided visual input for the entirety of each trial. The models were then tested on a memory guided motor task, where the visual target disappeared after a short duration. Sensory input to the neural networks had sensory delays consistent with results from monkey studies. We found that lateral connections within the PPC resulted in smoother movements and were necessary for accurate movements in the absence of visual input. The addition of lateral connections resulted in velocity profiles consistent with those observed in human and non-human primate visually guided studies of reaching, and allowed for smooth, rapid, and accurate movements under all conditions. In contrast, Feedforward or Feedback architectures were insufficient to overcome these challenges. Our results suggest that intrinsic lateral connections are critical for executing accurate, smooth motor plans.

  3. A Current-Forced Line-Commutated Inverter for Single-Phase Grid-Connected Photovoltaic Generation Systems

    OpenAIRE

    2015-01-01

    A simple power electronic interface based on the line-commutated inverter (LCI) has been developed in order to inject sinusoidal current to the grid for single-phase grid-connected photovoltaic (PV) energy generation systems. The proposed inverter facilitates controlling the injecting/grid current with a controllable power factor in contrast to the conventional LCI system. It is achieved that the total harmonic distortion (THD) of the injecting currents for the different firin...

  4. Fuzzy Logic Control of Wind Turbine System Connection to PM Synchronous Generator for Maximum Power Point Tracking

    Directory of Open Access Journals (Sweden)

    Hadi Sefidgar

    2014-06-01

    Full Text Available in this paper, a fuzzy logic control (FLC is proposed for maximum power point tracking (MPPT in wind turbine connection to Permanent Magnet Synchronous Generator (PMSG. The proposed fuzzy logic controller tracks the maximum power point (MPP by measurements the load voltage and current. This controller calculates the load power and sent through the fuzzy logic system. The main goal of this paper is design of the fuzzy logic controller in the model of DC-DC converter (boost converter. This method allows the MPPT controller output (duty cycle adjusts the voltage input to the converter to track the maximum power point of the wind generator.

  5. On Realistic Demand of the New Generation of Migrant Workers in China%我国新生代农民工的现实诉求探析

    Institute of Scientific and Technical Information of China (English)

    宋平

    2015-01-01

    This article summed up the new generation of migrant workers ’ real life demands from six aspects:the desire for human care ,cultural education needs ,their own development ,integration into the city ,the maintenance of the rights and interests ,participation in politics and other aspects .And discussed the main reason of the new genera-tion of migrant workers from six dimensions , put forward the major way to solve the reasonable demands so as to cause the social concern and promote the society to be more harmonious and stable .%从渴望人文关怀、文化教育需求、自身发展、融入城市、维护权益、参与政治等六个方面归纳了我国新生代农民工对现实生活的诉求,又从六个维度探讨了新生代农民工诉求的主要原因,提出了解决其合理诉求的主要途径,以期引起政府部门和社会的关注,帮助新生代农民工走出利益诉求困境,促进全社会和谐稳定。

  6. Controls on Connectivity and Streamflow Generation in a Canadian Prairie Landscape

    Science.gov (United States)

    Brannen, R.; Spence, C.; Ireson, A. M.

    2013-12-01

    In the semi-arid, internally drained Prairie Pothole Region, the large volume of surface storage in depressional wetlands is a major factor in determining the extent and distribution of surface connections between wetlands. At catchment and sub-catchment scales, storage thresholds of different wetlands have been observed to control the connectivity of landscape components and the timing and degree of streamflow. We used a wide range of field observations in a 1 km2 sub-catchment in central Saskatchewan to analyze the surface and subsurface processes that contribute to or draw on basin storage, and how this controls the connectivity of stream networks and basin streamflow. It is well understood how surface water storage in depressions changes over time due to processes of snowmelt runoff, infiltration, and evapotranspiration. Missing is a quantification of the groundwater processes that may sustain surface storage in wetlands and prolong the receding limb of stream hydrographs. Although current models are capable of predicting many hydrological processes in this region, they do not integrate dynamic surface and subsurface processes that together influence the connectivity of headwater resources to downstream areas. In spring 2013, it was observed that surface storage capacity within wetland ponds mediated the streamflow response and occurrence of spills between wetlands, in accordance with the ';fill-spill' theory for prairie wetlands. The flux of shallow groundwater between pond and upland was negligible during snowmelt, as the water balance of ponds was dominated by the snowmelt signal from a larger than average winter snowpack. Gradual pond recession and sustained streamflow well into the summer season suggests that groundwater exchange may be a control on maintaining the water level of ponds above spill threshold.

  7. Connecting the Water and Carbon Cycles for the Generation of Food Security and Ecosystem Services

    OpenAIRE

    Burke, Shivaan M.; Poncé-Hernandez, Raul

    2014-01-01

    Water scarcity and food insecurity are pervasive issues in the developing world and are also intrinsically linked to one another. Through the connection of the water cycle and the carbon cycle this study illustrates that synergistic benefits can be realized by small scale farmers through the implementation of waste water irrigated agroforestry. The WaNuLCAS model is employed using La Huerta agroforestry site in Texcoco, South Central Mexico, as the basis for parameterization. The results of m...

  8. Some methods to connect a windpower induction generator to the utility network

    Science.gov (United States)

    Carlsson, O.; Hylander, J.

    1981-04-01

    When an induction generator is switched on to a grid, heavy inrush currents may appear, which may result in a transient voltage variation. By using inductors or thyristors in series with the generator, or capacitor excitation before synchronizing it, the inrush currents could be limited to acceptable levels.

  9. Kuhn: Realist or Antirealist?

    Directory of Open Access Journals (Sweden)

    Michel Ghins

    1998-06-01

    Full Text Available Although Kuhn is much more an antirealist than a realist, the earlier and later articulations of realist and antirealist ingredients in his views merit close scrutiny. What are the constituents of the real invariant World posited by Kuhn and its relation to the mutable paradigm-related worlds? Various proposed solutions to this problem (dubbed the "new-world problem" by Ian Hacking are examined and shown to be unsatisfactory. In The Structure of Scientific Revolutions, the stable World can reasonably be taken to be made up of ordinary perceived objects, whereas in Kuhn's later works the transparadigmatic World is identified with something akin to the Kantian world-in-itself. It is argued that both proposals are beset with insuperable difficulties which render Kuhn's earlier and later versions of antirealism implausible.

  10. Analysis and estimation of transient stability for a grid-connected wind turbine with induction generator

    DEFF Research Database (Denmark)

    Li, H.; Zhao, B.; Yang, C.

    2011-01-01

    Increasing levels of wind energy in modern electrical power system is initiating a need for accurate analysis and estimation of transient stability of wind turbine generation systems. This paper investigates the transient behaviors and possible direct methods for transient stability evaluation...... electromagnetic transient models of a SCIG, the transient behaviors of the wind turbine generation system during a three-phase fault are simulated and compared with the traditional models. Secondly, in order to quickly estimate the transient stability limit of the wind turbine generation system, a direct method...... based on normal form theory is proposed. The transient models of the wind turbine generation system including the flexible drive train model are derived based on the direct transient stability estimation method. A method of critical clearing time (CCT) calculation is developed for the transient...

  11. Adaptive Droop Control Applied to Distributed Generation Inverters Connected to the Grid

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Teodorescu, Remus; Vásquez, Juan C.

    2008-01-01

    This paper proposes a novel control for voltage source inverters connected to the grid. The control scheme is based on the droop method, and it uses some estimated variables from the grid such as the voltage and the frequency, and the magnitude and angle of the grid impedance. Hence, the inverter...... is able to inject independently active and reactive power to the grid. The controller provides a proper dynamics decoupled from the grid impedance. Simulation results are provided in order to show the feasibility of the control proposed....

  12. A Battery-less Grid Connected Photovoltaic Power generation using Five-Level Common-Emitter Current-Source Inverter

    Directory of Open Access Journals (Sweden)

    Suroso Suroso

    2014-12-01

    Full Text Available Renewable power generation using photovoltaic is very interesting to be developed to deal with the problems of conventional energy sources and environmental issues. The photovoltaic power generation can operate both in stand-alone and grid-connected operations. This paper presents an application of the five-level common-emitter current-source inverter (CE-CSI for grid connected photovoltaic system without batteries as energy storage system. In the proposed system, the five-level CE-CSI works generating a sinusoidal output current from photovoltaic system to be injected into the power grid. The transformer is used in the system to step-down the grid voltage to meet the voltage level of the photovoltaic system, and also works as a galvanic insulation between the power grid and the inverter system. Two conditions of the power grid voltage, i.e. a pure sinusoidal and a distorted power grid, are tested through computer simulation using PSIM software. Furthermore, experimental test result of the five-level inverter is also presented. The test results show that the five-level CE-CSI works well injecting a sinusoidal current into the power grid with low harmonic contents, and with unity power factor operation. The results also show that the distorted grid voltage affects the harmonic contents of the current injected by the inverter.

  13. Dynamic model of Stirling engine crank mechanism with connected electric generator

    Directory of Open Access Journals (Sweden)

    Vlach R.

    2009-06-01

    Full Text Available This paper treats of a numerical dynamic model of Stirling engine crank mechanism. The model is included in the complex model of combined heat and power unit. The unit is composed of the Stirling engine and of attached three-phase synchronous generator. This generator should start the Stirling engine in motor mode as well. It is necessary to combine the crank shaft dynamic model and the complete thermal model of Stirling engine for simulations and analyses of engine run. Our aim is to create a dynamics model which takes into account the parameters of crankshaft, piston rods, pistons, and attached generator. For unit working, the electro-mechanical behaviour of generator is also important. That is why we experimentally verified the parameters of generator. The measured characteristics are used in a complex model of heat and power unit. Moreover, it is also possible to determine the Stirling engine torque by the help of these electro-mechanical characteristics. These values can be used e. g. for determination of optimal engine working point or for unit control.

  14. Generation and detection of spin polarization in parallel coupled double quantum dots connected to four terminals

    Energy Technology Data Exchange (ETDEWEB)

    An, Xing-Tao, E-mail: anxt2005@163.com [School of Sciences, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018 (China); Mu, Hui-Ying [Department of Chemistry and Environmental Engineering, Hebei Chemical and Pharmaceutical Vocational Technology College, Shijiazhuang, Hebei 050026 (China); Li, Yu-Xian [College of Physical Science and Information Engineering, Hebei Normal University, and Hebei Advanced Thin Films Laboratory, Shijiazhuang, Hebei 050016 (China); Liu, Jian-Jun [College of Physical Science and Information Engineering, Hebei Normal University, and Hebei Advanced Thin Films Laboratory, Shijiazhuang, Hebei 050016 (China); Physics Department, Shijiazhuang University, Shijiazhuang 050035 (China)

    2011-10-31

    A four-terminal parallel double quantum dots (QDs) device is proposed to generate and detect the spin polarization in QDs. It is found that the spin accumulation in QDs and the spin-polarized currents in the upper and down leads can be generated when a bias voltage is applied between the left and right leads. It is more interesting that the spin polarization in the QDs can be detected using the upper and down leads. Moreover, the direction and magnitude of the spin polarization in the QDs, and in the upper and down leads can be tuned by the energy levels of QDs and the bias. -- Highlights: → The spin polarization in the quantum dots can be generated and controlled. → The spin polarization in quantum dots can be detected by the nonferromagnetic leads. → The system our studied is a discrete level spin Hall system.

  15. A Current-Forced Line-Commutated Inverter for Single-Phase Grid-Connected Photovoltaic Generation Systems

    Directory of Open Access Journals (Sweden)

    UNLU, M.

    2015-05-01

    Full Text Available A simple power electronic interface based on the line-commutated inverter (LCI has been developed in order to inject sinusoidal current to the grid for single-phase grid-connected photovoltaic (PV energy generation systems. The proposed inverter facilitates controlling the injecting/grid current with a controllable power factor in contrast to the conventional LCI system. It is achieved that the total harmonic distortion (THD of the injecting currents for the different firing angles/power factors and reference currents is about 5% or less than 5%. Thus, the grid-connected standards for injecting current are satisfied without filter equipment unlike the conventional LCI system. The proposed system has been built in MATLAB/Simulink and examined experimentally on PV array of 160 W. The simulation and experimental results are better performance than the conventional line-commutated inverter methods reported in the literature. The proposed LCI has a simple and robust structure, and it can be easily synchronized with grid thanks to self-latching property of SCRs. Therefore, it is a good alternative for the power transferring from PV panels to the utility grid in grid-connected PV systems.

  16. Evaluation of a Wind Turbine Generation System Connected to Distribution Network from Viewpoint of Acceptable Maximum Output

    Science.gov (United States)

    Hanai, Yuji; Hayashi, Yasuhiro; Matsuki, Junya; Kobayashi, Naoki

    Recently, the total number of Wind Turbine Generation System (WTGS) connected to distribution network has been increased drastically. Installation of WTGS can reduce the distribution loss and emission of CO2. However, the distribution network with WTGS must be operated keeping reliability of power supply and power quality. The WTGS's effects to distribution network depend on its structure. In order to accomplish both the stable operation of distribution network and the progress of WTGS's prevalence, it is necessary to evaluate the acceptable output of WTGS quantitatively. In this paper, the authors evaluate several WTGSs connected to distribution network from viewpoint of Acceptable Maximum Output (AMO). The operational constrains to calculate the AMO of a WTGS are the following, (1) voltage limit, (2) line current capacity, (3) no reverse flow to distribution transformer, (4) short circuit capacity, and (5) voltage dip by inrush current. In order to evaluate the WTGS from viewpoint of AMO, numerical simulations are accomplished for a distribution system model. Furthermore, characteristics of AMO of a WTGS connected to distribution feeder are analyzed by several numerical examples.

  17. From grid cells to place cells with realistic field sizes.

    Science.gov (United States)

    Neher, Torsten; Azizi, Amir Hossein; Cheng, Sen

    2017-01-01

    While grid cells in the medial entorhinal cortex (MEC) of rodents have multiple, regularly arranged firing fields, place cells in the cornu ammonis (CA) regions of the hippocampus mostly have single spatial firing fields. Since there are extensive projections from MEC to the CA regions, many models have suggested that a feedforward network can transform grid cell firing into robust place cell firing. However, these models generate place fields that are consistently too small compared to those recorded in experiments. Here, we argue that it is implausible that grid cell activity alone can be transformed into place cells with robust place fields of realistic size in a feedforward network. We propose two solutions to this problem. Firstly, weakly spatially modulated cells, which are abundant throughout EC, provide input to downstream place cells along with grid cells. This simple model reproduces many place cell characteristics as well as results from lesion studies. Secondly, the recurrent connections between place cells in the CA3 network generate robust and realistic place fields. Both mechanisms could work in parallel in the hippocampal formation and this redundancy might account for the robustness of place cell responses to a range of disruptions of the hippocampal circuitry.

  18. A solar PV augmented hybrid scheme for enhanced wind power generation through improved control strategy for grid connected doubly fed induction generator

    Directory of Open Access Journals (Sweden)

    Adikanda Parida

    2016-12-01

    Full Text Available In this paper, a wind power generation scheme using a grid connected doubly fed induction generator (DFIG augmented with solar PV has been proposed. A reactive power-based rotor speed and position estimation technique with reduced machine parameter sensitivity is also proposed to improve the performance of the DFIG controller. The estimation algorithm is based on model reference adaptive system (MRAS, which uses the air gap reactive power as the adjustable variable. The overall generation reliability of the wind energy conversion system can be considerably improved as both solar and wind energy can supplement each other during lean periods of either of the sources. The rotor-side DC-link voltage and active power generation at the stator terminals of the DFIG are maintained constant with minimum storage battery capacity using single converter arrangement without grid-side converter (GSC. The proposed scheme has been simulated and experimentally validated with a practical 2.5 kW DFIG using dSPACE CP1104 module which produced satisfactory results.

  19. Differential Evolution Based IDWNN Controller for Fault Ride-Through of Grid-Connected Doubly Fed Induction Wind Generators.

    Science.gov (United States)

    Manonmani, N; Subbiah, V; Sivakumar, L

    2015-01-01

    The key objective of wind turbine development is to ensure that output power is continuously increased. It is authenticated that wind turbines (WTs) supply the necessary reactive power to the grid at the time of fault and after fault to aid the flowing grid voltage. At this juncture, this paper introduces a novel heuristic based controller module employing differential evolution and neural network architecture to improve the low-voltage ride-through rate of grid-connected wind turbines, which are connected along with doubly fed induction generators (DFIGs). The traditional crowbar-based systems were basically applied to secure the rotor-side converter during the occurrence of grid faults. This traditional controller is found not to satisfy the desired requirement, since DFIG during the connection of crowbar acts like a squirrel cage module and absorbs the reactive power from the grid. This limitation is taken care of in this paper by introducing heuristic controllers that remove the usage of crowbar and ensure that wind turbines supply necessary reactive power to the grid during faults. The controller is designed in this paper to enhance the DFIG converter during the grid fault and this controller takes care of the ride-through fault without employing any other hardware modules. The paper introduces a double wavelet neural network controller which is appropriately tuned employing differential evolution. To validate the proposed controller module, a case study of wind farm with 1.5 MW wind turbines connected to a 25 kV distribution system exporting power to a 120 kV grid through a 30 km 25 kV feeder is carried out by simulation.

  20. Differential Evolution Based IDWNN Controller for Fault Ride-Through of Grid-Connected Doubly Fed Induction Wind Generators

    Directory of Open Access Journals (Sweden)

    N. Manonmani

    2015-01-01

    Full Text Available The key objective of wind turbine development is to ensure that output power is continuously increased. It is authenticated that wind turbines (WTs supply the necessary reactive power to the grid at the time of fault and after fault to aid the flowing grid voltage. At this juncture, this paper introduces a novel heuristic based controller module employing differential evolution and neural network architecture to improve the low-voltage ride-through rate of grid-connected wind turbines, which are connected along with doubly fed induction generators (DFIGs. The traditional crowbar-based systems were basically applied to secure the rotor-side converter during the occurrence of grid faults. This traditional controller is found not to satisfy the desired requirement, since DFIG during the connection of crowbar acts like a squirrel cage module and absorbs the reactive power from the grid. This limitation is taken care of in this paper by introducing heuristic controllers that remove the usage of crowbar and ensure that wind turbines supply necessary reactive power to the grid during faults. The controller is designed in this paper to enhance the DFIG converter during the grid fault and this controller takes care of the ride-through fault without employing any other hardware modules. The paper introduces a double wavelet neural network controller which is appropriately tuned employing differential evolution. To validate the proposed controller module, a case study of wind farm with 1.5 MW wind turbines connected to a 25 kV distribution system exporting power to a 120 kV grid through a 30 km 25 kV feeder is carried out by simulation.

  1. High-Performance Constant Power Generation in Grid-Connected PV Systems

    DEFF Research Database (Denmark)

    Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede

    2016-01-01

    An advanced power control strategy by limiting the maximum feed-in power of PV systems has been proposed, which can ensure a fast and smooth transition between maximum power point tracking and Constant Power Generation (CPG). Regardless of the solar irradiance levels, high-performance and stable...... operation are always achieved by the proposed control strategy. It can regulate the PV output power according to any set-point, and force the PV systems to operate at the left side of the maximum power point without stability problems. Experimental results have verified the effectiveness of the proposed CPG...

  2. The PWM strategies of grid-connected distributed generation active NPC inverters

    DEFF Research Database (Denmark)

    Ma, Lin; Xinmin, Jin; Kerekes, Tamas

    2009-01-01

    The Neutral Point Clamped topology due to high efficiency, low leakage current and EMI, its integration is widely used in the distributed generation (DG) systems. However the main disadvantage of the NPC inverter is given by an unequal distribution of the losses in the semiconductor devices, which...... leads to an unequal distribution of temperature. By using the Active NPC topology, the power losses distribution problem is alleviated. The modulation strategy is a key issue for losses distribution in this topology. In this paper two known strategies are discussed and a new proposed PWM strategy...

  3. A Serially-Connected Compensator for Eliminating the Unbalanced Three-Phase Voltage Impact on Wind Turbine Generators

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Ziping; Hsu, Ping; Muljadi, Eduard; Gao, Wenzhong

    2015-10-05

    Untransposed transmission lines, unbalanced tap changer operations, and unbalanced loading in weak distribution lines can cause unbalanced-voltage conditions. The resulting unbalanced voltage at the point of interconnection affects proper gird integration and reduces the lifetime of wind turbines due to power oscillations, torque pulsations, mechanical stresses, energy losses, and uneven and overheating of the generator stator winding. This work investigates the dynamic impact of unbalanced voltage on the mechanical and electrical components of integrated Fatigue, Aerodynamics, Structures, and Turbulence (FAST) wind turbine generation systems (WTGs) of Type 1 (squirrel-cage induction generator) and Type 3 (doubly-fed induction generator). To alleviate this impact, a serially-connected compensator for a three-phase power line is proposed to balance the wind turbine-side voltage. Dynamic simulation studies are conducted in MATLAB/Simulink to compare the responses of these two types of wind turbine models under normal and unbalanced-voltage operation conditions and demonstrate the effectiveness of the proposed compensator.

  4. Serially-Connected Compensator for Eliminating the Unbalanced Three-Phase Voltage Impact on Wind Turbine Generators: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Z.; Hsu, P.; Muljadi, E.; Gao, W.

    2015-04-06

    Untransposed transmission lines, unbalanced tap changer operations, and unbalanced loading in weak distribution lines can cause unbalanced-voltage conditions. The resulting unbalanced voltage at the point of interconnection affects proper gird integration and reduces the lifetime of wind turbines due to power oscillations, torque pulsations, mechanical stresses, energy losses, and uneven and overheating of the generator stator winding. This work investigates the dynamic impact of unbalanced voltage on the mechanical and electrical components of integrated Fatigue, Aerodynamics, Structures, and Turbulence (FAST) wind turbine generation systems (WTGs) of Type 1 (squirrel-cage induction generator) and Type 3 (doubly-fed induction generator). To alleviate this impact, a serially-connected compensator for a three-phase power line is proposed to balance the wind turbine-side voltage. Dynamic simulation studies are conducted in MATLAB/Simulink to compare the responses of these two types of wind turbine models under normal and unbalanced-voltage operation conditions and demonstrate the effectiveness of the proposed compensator.

  5. The contribution to distribution network fault levels from the connection of distributed generation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This report summarises the findings of a study investigating the potential impact of distributed generation (DG) on the UK distribution network fault levels up to the year 2010, and examining ways of managing the fault levels so that they do not become a barrier to increased penetration of DG. The project focuses on the circumstances and scenarios that give rise to the fault levels. The background to the study is traced, and a technical review is presented covering the relationship between DG and fault levels, and the likely impact in the period to 2010. Options for managing increased fault levels, and fault level management and costs are outlined, and a case study is given. The measurement and calculation of fault level values are described along with constraints to DG penetration due to fault level limitations, characteristics of DG machines, and long term perspectives to 2020-2030.

  6. Control strategy of hybrid fuel cell/battery distributed generation system for grid-connected operation

    Institute of Scientific and Technical Information of China (English)

    Masoud Aliakbar GOLKAR; Amin HAJIZADEH

    2009-01-01

    This paper presents a control strategy of a hybrid fuel cell/battery distributed generation (HDG) system in distribution systems. The overall structure of the HDG system is given, dynamic models for the solid oxide fuel cell (SOFC) power plant,battery bank and its power electronic interfacing are briefly described, and controller design methodologies for the power conditioning units and fuel cell to control the power flow from the hybrid power plant to the utility grid are presented. To distribute the power between the fuel cell power plant and the battery energy storage, a neuro-fuzzy controller has been developed. Also, for controlling the active and reactive power independently in distribution systems, the current control strategy based on two fuzzy logic controllers has been presented. A Matlab/Simulink simulation model is developed for the HDG system by combining the individual component models and their controllers. Simulation results show the overall system performance including load-following and power management of the HDG system.

  7. Quantification of wing and body kinematics in connection to torque generation during damselfly yaw turn

    Science.gov (United States)

    Zeyghami, Samane; Bode-Oke, Ayodeji T.; Dong, HaiBo

    2017-01-01

    This study provides accurate measurements of the wing and body kinematics of three different species of damselflies in free yaw turn flights. The yaw turn is characterized by a short acceleration phase which is immediately followed by an elongated deceleration phase. Most of the heading change takes place during the latter stage of the flight. Our observations showed that yaw turns are executed via drastic rather than subtle changes in the kinematics of all four wings. The motion of the inner and outer wings were found to be strongly linked through their orientation as well as their velocities with the inner wings moving faster than the outer wings. By controlling the pitch angle and wing velocity, a damselfly adjusts the angle of attack. The wing angle of attack exerted the strongest influence on the yaw torque, followed by the flapping and deviation velocities of the wings. Moreover, no evidence of active generation of counter torque was found in the flight data implying that deceleration and stopping of the maneuver is dominated by passive damping. The systematic analysis carried out on the free flight data advances our understanding of the mechanisms by which these insects achieve their observed maneuverability. In addition, the inspiration drawn from this study can be employed in the design of low frequency flapping wing micro air vehicles (MAV's).

  8. Electricity generation and microbial community in response to short-term changes in stack connection of self-stacked submersible microbial fuel cell powered by glycerol

    DEFF Research Database (Denmark)

    Zhao, Nannan; Angelidaki, Irini; Zhang, Yifeng

    2017-01-01

    Stack connection (i.e., in series or parallel) of microbial fuel cell (MFC) is an efficient way to boost the power output for practical application. However, there is little information available on short-term changes in stack connection and its effect on the electricity generation and microbial...... community. In this study, a self-stacked submersible microbial fuel cell (SSMFC) powered by glycerol was tested to elucidate this important issue. In series connection, the maximum voltage output reached to 1.15 V, while maximum current density was 5.73 mA in parallel. In both connections, the maximum power...... density increased with the initial glycerol concentration. However, the glycerol degradation was even faster in parallel connection. When the SSMFC was shifted from series to parallel connection, the reactor reached to a stable power output without any lag phase. Meanwhile, the anodic microbial community...

  9. Optimal Dispatch of Unreliable Electric Grid-Connected Diesel Generator-Battery Power Systems

    Science.gov (United States)

    Xu, D.; Kang, L.

    2015-06-01

    Diesel generator (DG)-battery power systems are often adopted by telecom operators, especially in semi-urban and rural areas of developing countries. Unreliable electric grids (UEG), which have frequent and lengthy outages, are peculiar to these regions. DG-UEG-battery power system is an important kind of hybrid power system. System dispatch is one of the key factors to hybrid power system integration. In this paper, the system dispatch of a DG-UEG-lead acid battery power system is studied with the UEG of relatively ample electricity in Central African Republic (CAR) and UEG of poor electricity in Congo Republic (CR). The mathematical models of the power system and the UEG are studied for completing the system operation simulation program. The net present cost (NPC) of the power system is the main evaluation index. The state of charge (SOC) set points and battery bank charging current are the optimization variables. For the UEG in CAR, the optimal dispatch solution is SOC start and stop points 0.4 and 0.5 that belong to the Micro-Cycling strategy and charging current 0.1 C. For the UEG in CR, the optimal dispatch solution is of 0.1 and 0.8 that belongs to the Cycle-Charging strategy and 0.1 C. Charging current 0.1 C is suitable for both grid scenarios compared to 0.2 C. It makes the dispatch strategy design easier in commercial practices that there are a few very good candidate dispatch solutions with system NPC values close to that of the optimal solution for both UEG scenarios in CAR and CR.

  10. Dynamic imaging of coherent sources reveals different network connectivity underlying the generation and perpetuation of epileptic seizures.

    Directory of Open Access Journals (Sweden)

    Lydia Elshoff

    Full Text Available The concept of focal epilepsies includes a seizure origin in brain regions with hyper synchronous activity (epileptogenic zone and seizure onset zone and a complex epileptic network of different brain areas involved in the generation, propagation, and modulation of seizures. The purpose of this work was to study functional and effective connectivity between regions involved in networks of epileptic seizures. The beginning and middle part of focal seizures from ictal surface EEG data were analyzed using dynamic imaging of coherent sources (DICS, an inverse solution in the frequency domain which describes neuronal networks and coherences of oscillatory brain activities. The information flow (effective connectivity between coherent sources was investigated using the renormalized partial directed coherence (RPDC method. In 8/11 patients, the first and second source of epileptic activity as found by DICS were concordant with the operative resection site; these patients became seizure free after epilepsy surgery. In the remaining 3 patients, the results of DICS / RPDC calculations and the resection site were discordant; these patients had a poorer post-operative outcome. The first sources as found by DICS were located predominantly in cortical structures; subsequent sources included some subcortical structures: thalamus, Nucl. Subthalamicus and cerebellum. DICS seems to be a powerful tool to define the seizure onset zone and the epileptic networks involved. Seizure generation seems to be related to the propagation of epileptic activity from the primary source in the seizure onset zone, and maintenance of seizures is attributed to the perpetuation of epileptic activity between nodes in the epileptic network. Despite of these promising results, this proof of principle study needs further confirmation prior to the use of the described methods in the clinical praxis.

  11. Toward the classification of the realistic free fermionic models

    Energy Technology Data Exchange (ETDEWEB)

    Faraggi, A.E.

    1997-08-01

    The realistic free fermionic models have had remarkable success in providing plausible explanations for various properties of the Standard Model which include the natural appearance of three generations, the explanation of the heavy top quark mass and the qualitative structure of the fermion mass spectrum in general, the stability of the proton and more. These intriguing achievements makes evident the need to understand the general space of these models. While the number of possibilities is large, general patterns can be extracted. In this paper the author presents a detailed discussion on the construction of the realistic free fermionic models with the aim of providing some insight into the basic structures and building blocks that enter the construction. The role of free phases in the determination of the phenomenology of the models is discussed in detail. The author discusses the connection between the free phases and mirror symmetry in (2,2) models and the corresponding symmetries in the case of (2,0) models. The importance of the free phases in determining the effective low energy phenomenology is illustrated in several examples. The classification of the models in terms of boundary condition selection rules, real world-sheet fermion pairings, exotic matter states and the hidden sector is discussed.

  12. Integration of Hybrid PV/Wind Generation System Using Fuzzy MPPT in Grid Connected System for Remote Area

    Directory of Open Access Journals (Sweden)

    Soedibyo

    2016-01-01

    Full Text Available Photovoltaic and wind are renewable energy resources that widely used and grow rapidly in fulfilling electricity demand. Powers from both technologies depend on sunlight intensity and wind speed. For small scale power generation, DC voltage from both technologies is low and requires step-up converter to raise DC voltage ratio before converted into AC voltage. To optimize this system, step-up converter must have high ratio and efficiency to a distance of wide voltage input. This paper proposed an operation simulation and arrangement of DC-DC converter along with DC-AC from hybrid source PV-Wind which integrated to grid utilities without using storage device. High Gain Integrated Cascade Boost (HGICB is DC-DC converter that has quadratic voltage ratio and used in this research. Then DC link connected to Voltage Source Inverter (VSI which interconnected with utility grid and controlled by current control method. The total installed capacity of hybrid source is 4.4 kW. Wind turbine uses PMSG along with full bridge rectifier. To maximize and stabilize the generated power, MPPT fuzzy is used. Result from the simulation shows that converter capable to maintain maximum power whether from PV and wind turbine which canalized to utility grid in various irradiation condition, wind speed, and grid load alteration.

  13. ANALYSIS OF MONTE CARLO SIMULATION SAMPLING TECHNIQUES ON SMALL SIGNAL STABILITY OF WIND GENERATOR- CONNECTED POWER SYSTEM

    Directory of Open Access Journals (Sweden)

    TEMITOPE RAPHAEL AYODELE

    2016-04-01

    Full Text Available Monte Carlo simulation using Simple Random Sampling (SRS technique is popularly known for its ability to handle complex uncertainty problems. However, to produce a reasonable result, it requires huge sample size. This makes it to be computationally expensive, time consuming and unfit for online power system applications. In this article, the performance of Latin Hypercube Sampling (LHS technique is explored and compared with SRS in term of accuracy, robustness and speed for small signal stability application in a wind generator-connected power system. The analysis is performed using probabilistic techniques via eigenvalue analysis on two standard networks (Single Machine Infinite Bus and IEEE 16–machine 68 bus test system. The accuracy of the two sampling techniques is determined by comparing their different sample sizes with the IDEAL (conventional. The robustness is determined based on a significant variance reduction when the experiment is repeated 100 times with different sample sizes using the two sampling techniques in turn. Some of the results show that sample sizes generated from LHS for small signal stability application produces the same result as that of the IDEAL values starting from 100 sample size. This shows that about 100 sample size of random variable generated using LHS method is good enough to produce reasonable results for practical purpose in small signal stability application. It is also revealed that LHS has the least variance when the experiment is repeated 100 times compared to SRS techniques. This signifies the robustness of LHS over that of SRS techniques. 100 sample size of LHS produces the same result as that of the conventional method consisting of 50000 sample size. The reduced sample size required by LHS gives it computational speed advantage (about six times over the conventional method.

  14. Generation connected with images

    Directory of Open Access Journals (Sweden)

    Adriana RECAMÁN PAYO

    2011-12-01

    Full Text Available 0 0 1 197 1086 Instituto Universitario de Ciencias de la Educación 9 2 1281 14.0 Normal 0 21 false false false ES JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-ansi-language:ES; mso-fareast-language:EN-US;} In learning contexts studying the image as a focus of sensitive knowledge and formative purposes is crucial to achieve high levels of quality and educational excellence. As Renobell (2005 stated, image analysis encourages the development of critical capacity and contributes to developing a personal style for the gradual acquisition of a visual culture. Images educate and consequently, their presence in the field of education should not be a mere accompaniment to the text. They should not be limited to adorn or illustrate a linguistic content but to complement and deepen it, activating the thought and the reflection of the reader. In Internet culture, image as a focus of knowledge, of shared use, of social content and educational purposes, contribute to explain the implications and vivacity around this technological environment, which plays a leading role in the current social changes and movements. The culture of the network has changed our perceptual sensitivity to interpret images, which are now more complex, integrated, multidimensional and dynamic than ever. The interactivity, the strong relationship with the text content, the graphic sequentiality, the associated sound effects or the iconical text design reveal the importance of image in the net culture.

  15. Electricity generation and microbial community in response to short-term changes in stack connection of self-stacked submersible microbial fuel cell powered by glycerol.

    Science.gov (United States)

    Zhao, Nannan; Angelidaki, Irini; Zhang, Yifeng

    2017-02-01

    Stack connection (i.e., in series or parallel) of microbial fuel cell (MFC) is an efficient way to boost the power output for practical application. However, there is little information available on short-term changes in stack connection and its effect on the electricity generation and microbial community. In this study, a self-stacked submersible microbial fuel cell (SSMFC) powered by glycerol was tested to elucidate this important issue. In series connection, the maximum voltage output reached to 1.15 V, while maximum current density was 5.73 mA in parallel. In both connections, the maximum power density increased with the initial glycerol concentration. However, the glycerol degradation was even faster in parallel connection. When the SSMFC was shifted from series to parallel connection, the reactor reached to a stable power output without any lag phase. Meanwhile, the anodic microbial community compositions were nearly stable. Comparatively, after changing parallel to series connection, there was a lag period for the system to get stable again and the microbial community compositions became greatly different. This study is the first attempt to elucidate the influence of short-term changes in connection on the performance of MFC stack, and could provide insight to the practical utilization of MFC.

  16. Storage dynamics in hydropedological units control hillslope connectivity, runoff generation, and the evolution of catchment transit time distributions.

    Science.gov (United States)

    Tetzlaff, D; Birkel, C; Dick, J; Geris, J; Soulsby, C

    2014-02-01

    We examined the storage dynamics and isotopic composition of soil water over 12 months in three hydropedological units in order to understand runoff generation in a montane catchment. The units form classic catena sequences from freely draining podzols on steep upper hillslopes through peaty gleys in shallower lower slopes to deeper peats in the riparian zone. The peaty gleys and peats remained saturated throughout the year, while the podzols showed distinct wetting and drying cycles. In this region, most precipitation events are 80% of flow, even in large events, reflecting the displacement of water from the riparian soils that has been stored in the catchment for >2 years. These riparian areas are the key zone where different source waters mix. Our study is novel in showing that they act as "isostats," not only regulating the isotopic composition of stream water, but also integrating the transit time distribution for the catchment. Hillslope connectivity is controlled by small storage changes in soil unitsDifferent catchment source waters mix in large riparian wetland storageIsotopes show riparian wetlands set the catchment transit time distribution.

  17. Electrostatic generator/motor having rotors of varying thickness and a central stator electrically connected together into two groups

    Science.gov (United States)

    Post, Richard F.

    2010-11-16

    A sub-module consists of a set of two outer sets of stationary fan-blade-shaped sectors. These outer sectors include conductive material and are maintained at ground potential in several examples. Located midway between them is a set of stationary sector plates with each plate being electrically insulated from the others. An example provides that the inner sector plates are connected together alternately, forming two groups of parallel-connected condensers that are then separately connected, through high charging circuit resistances, to a source of DC potential with respect to ground, with an additional connecting lead being provided for each group to connect their output as an AC output to a load. These same leads can he used, when connected to a driver circuit, to produce motor action.

  18. RAMESES publication standards: realist syntheses

    Directory of Open Access Journals (Sweden)

    Wong Geoff

    2013-01-01

    Full Text Available Abstract Background There is growing interest in realist synthesis as an alternative systematic review method. This approach offers the potential to expand the knowledge base in policy-relevant areas - for example, by explaining the success, failure or mixed fortunes of complex interventions. No previous publication standards exist for reporting realist syntheses. This standard was developed as part of the RAMESES (Realist And MEta-narrative Evidence Syntheses: Evolving Standards project. The project's aim is to produce preliminary publication standards for realist systematic reviews. Methods We (a collated and summarized existing literature on the principles of good practice in realist syntheses; (b considered the extent to which these principles had been followed by published syntheses, thereby identifying how rigor may be lost and how existing methods could be improved; (c used a three-round online Delphi method with an interdisciplinary panel of national and international experts in evidence synthesis, realist research, policy and/or publishing to produce and iteratively refine a draft set of methodological steps and publication standards; (d provided real-time support to ongoing realist syntheses and the open-access RAMESES online discussion list so as to capture problems and questions as they arose; and (e synthesized expert input, evidence syntheses and real-time problem analysis into a definitive set of standards. Results We identified 35 published realist syntheses, provided real-time support to 9 on-going syntheses and captured questions raised in the RAMESES discussion list. Through analysis and discussion within the project team, we summarized the published literature and common questions and challenges into briefing materials for the Delphi panel, comprising 37 members. Within three rounds this panel had reached consensus on 19 key publication standards, with an overall response rate of 91%. Conclusion This project used multiple

  19. Letter to the editor: Generation of self organized critical connectivity network map (SOCCNM) of randomly situated water bodies during flooding process

    OpenAIRE

    B. S. Daya Sagar

    2001-01-01

    This letter presents a brief framework based on nonlinear morphological transformations to generate a self organized critical connectivity network map (SOCCNM) in 2-dimensional space. This simple and elegant framework is implemented on a section that contains a few simulated water bodies to generate SOCCNM. This is based on a postulate that the randomly situated surface water bodies of various sizes and shapes self organize during flooding process.

  20. Letter to the editor: Generation of self organized critical connectivity network map (SOCCNM of randomly situated water bodies during flooding process

    Directory of Open Access Journals (Sweden)

    B. S. Daya Sagar

    2001-01-01

    Full Text Available This letter presents a brief framework based on nonlinear morphological transformations to generate a self organized critical connectivity network map (SOCCNM in 2-dimensional space. This simple and elegant framework is implemented on a section that contains a few simulated water bodies to generate SOCCNM. This is based on a postulate that the randomly situated surface water bodies of various sizes and shapes self organize during flooding process.

  1. Realistic face modeling based on multiple deformations

    Institute of Scientific and Technical Information of China (English)

    GONG Xun; WANG Guo-yin

    2007-01-01

    On the basis of the assumption that the human face belongs to a linear class, a multiple-deformation model is proposed to recover face shape from a few points on a single 2D image. Compared to the conventional methods, this study has the following advantages. First, the proposed modified 3D sparse deforming model is a noniterative approach that can compute global translation efficiently and accurately. Subsequently, the overfitting problem can be alleviated based on the proposed multiple deformation model. Finally, by keeping the main features, the texture generated is realistic. The comparison results show that this novel method outperforms the existing methods by using ground truth data and that realistic 3D faces can be recovered efficiently from a single photograph.

  2. Should scientific realists be platonists?

    DEFF Research Database (Denmark)

    Busch, Jacob; Morrison, Joe

    2015-01-01

    Realists about are arrived at by any inferen- tial route which eschews causes (§3), and nor is there any direct pressure for Scientific Real- ists to change their inferential methods (§4). We suggest that in order to maintain inferential parity with Scientific Realism, proponents of EIA need to give......Enhanced Indispensability Arguments (EIA) claim that Scientific Realists are committed to the existence of mathematical entities due to their reliance on Inference to the Best Explana- tion (IBE). Our central question concerns this purported parity of reasoning: do people who defend the EIA make...... an appropriate use of the resources of Scientific Realism (in particular, IBE) to achieve platonism? (§2) We argue that just because a variety of different inferential strategies can be employed by Scientific Realists does not mean that ontological conclusions concerning which things we should be Scientific...

  3. Realistic Visualization of Virtual Views

    DEFF Research Database (Denmark)

    Livatino, Salvatore

    2005-01-01

    Computer Graphics allows us today to visualize in real-time innumerable and amazing scenarios with no limits on viewpoint and viewing direction. However, to design accurate object models and to simulate all the physical phenomena occurring in analogous real situations often represents a job...... that can be impractical and sometime impossible. In addition, the artificial nature of data often makes visualized virtual scenarios not realistic enough. Not realistic in the sense that a synthetic scene is easy to discriminate visually from a natural scene. A new field of research has consequently...... developed and received much attention in recent years: Realistic Virtual View Synthesis. The main goal is a high fidelity representation of virtual scenarios while easing modeling and physical phenomena simulation. In particular, realism is achieved by the transfer to the novel view of all the physical...

  4. Photo-Realistic Image Synthesis and Virtual Cinematography

    DEFF Research Database (Denmark)

    Livatino, Salvatore

    2005-01-01

    Realistic Virtual View Synthesis is a new field of research that has received increasing attention in recent years. It is strictly related to the grown popularity of virtual reality and the spread of its applications, among which virtual photography and cinematography. The use of computer generated......: the augmented actor. Fundamental concepts and examples of methods proposed for realistic view synthesis based on the transfer of photo-realism from reference photographs to novel views, will be presented. The application of methods for realistic image synthesis to virtual cinematography will also be illustrated...

  5. Photo-Realistic Image Synthesis and Virtual Cinematography

    DEFF Research Database (Denmark)

    Livatino, Salvatore

    2005-01-01

    Realistic Virtual View Synthesis is a new field of research that has received increasing attention in recent years. It is strictly related to the grown popularity of virtual reality and the spread of its applications, among which virtual photography and cinematography. The use of computer generated......: the augmented actor. Fundamental concepts and examples of methods proposed for realistic view synthesis based on the transfer of photo-realism from reference photographs to novel views, will be presented. The application of methods for realistic image synthesis to virtual cinematography will also be illustrated...

  6. Exophobic quasi-realistic heterotic string vacua

    Energy Technology Data Exchange (ETDEWEB)

    Assel, Benjamin [Centre de Physique Theorique, Ecole Polytechnique, F-91128 Palaiseau (France); Christodoulides, Kyriakos [Dept. of Mathematical Sciences, University of Liverpool, Liverpool L69 7ZL (United Kingdom); Faraggi, Alon E., E-mail: faraggi@amtp.liv.ac.u [Dept. of Mathematical Sciences, University of Liverpool, Liverpool L69 7ZL (United Kingdom); Kounnas, Costas [Lab. Physique Theorique, Ecole Normale Superieure, F-75231 Paris 05 (France); Rizos, John [Department of Physics, University of Ioannina, GR45110 Ioannina (Greece)

    2010-01-25

    We demonstrate the existence of heterotic string vacua that are free of massless exotic fields. The need to break the non-Abelian GUT symmetries in k=1 heterotic string models by Wilson lines, while preserving the GUT embedding of the weak hypercharge and the GUT prediction sin{sup 2}theta{sub w}(M{sub GUT})=3/8, necessarily implies that the models contain states with fractional electric charge. Such states are severely restricted by observations, and must be confined or sufficiently massive and diluted. We construct the first quasi-realistic heterotic string models in which the exotic states do not appear in the massless spectrum, and only exist, as they must, in the massive spectrum. The SO(10) GUT symmetry is broken to the Pati-Salam subgroup. Our PS heterotic string models contain adequate Higgs representations to break the GUT and electroweak symmetry, as well as colour Higgs triplets that can be used for the missing partner mechanism. By statistically sampling the space of Pati-Salam vacua we demonstrate the abundance of quasi-realistic three generation models that are completely free of massless exotics, rendering it plausible that obtaining realistic Yukawa couplings may be possible in this space of models.

  7. Quantum coding theory with realistic physical constraints

    CERN Document Server

    Yoshida, Beni

    2010-01-01

    The following open problems, which concern a fundamental limit on coding properties of quantum codes with realistic physical constraints, are analyzed and partially answered here: (a) the upper bound on code distances of quantum error-correcting codes with geometrically local generators, (b) the feasibility of a self-correcting quantum memory. To investigate these problems, we study stabilizer codes supported by local interaction terms with translation and scale symmetries on a $D$-dimensional lattice. Our analysis uses the notion of topology emerging in geometric shapes of logical operators, which sheds a surprising new light on theory of quantum codes with physical constraints.

  8. Functional connectivity between parietal and frontal brain regions and intelligence in young children: the Generation R study.

    Science.gov (United States)

    Langeslag, Sandra J E; Schmidt, Marcus; Ghassabian, Akhgar; Jaddoe, Vincent W; Hofman, Albert; van der Lugt, Aad; Verhulst, Frank C; Tiemeier, Henning; White, Tonya J H

    2013-12-01

    It has been shown in adults that individual differences in intelligence are related to the integrity of the interaction between parietal and frontal brain regions. Since connectivity between distant brain regions strengthens during childhood, it is unclear when in the course of development this relationship emerges. Thus, the goal of this study was to determine whether parietal-frontal functional connectivity is associated with intelligence in young children. We performed independent component analyses on resting-state fMRI data of 115 children (6-8 years old) to select seed and target regions for a seed/target region correlation analysis. We found that higher nonverbal intelligence was associated with increased functional connectivity between right parietal and right frontal regions, and between right parietal and dorsal anterior cingulate regions. The association between intelligence and functional connectivity between certain brain regions was stronger in girls than boys. In conclusion, we found that connectivity between the parietal and frontal lobes is critically involved in intelligence in young children. Copyright © 2012 Wiley Periodicals, Inc.

  9. Time management: a realistic approach.

    Science.gov (United States)

    Jackson, Valerie P

    2009-06-01

    Realistic time management and organization plans can improve productivity and the quality of life. However, these skills can be difficult to develop and maintain. The key elements of time management are goals, organization, delegation, and relaxation. The author addresses each of these components and provides suggestions for successful time management.

  10. Assessment and realistic mathematics education

    NARCIS (Netherlands)

    Heuvel-Panhuizen, M.H.A.M. van den

    1996-01-01

    This book describes the consequences of Realistic Mathematics Education (RME) for assessing students’ understanding of mathematics in primary school. RME is the Dutch answer to the worldwide need to reform mathematics education. Changed ideas about mathematics as a school subject, its goals, ideas a

  11. Probabilistic Bisimulation for Realistic Schedulers

    DEFF Research Database (Denmark)

    Eisentraut, Christian; Godskesen, Jens Christian; Hermanns, Holger

    2015-01-01

    . This holds in the classical context of arbitrary schedulers, but it has been argued that this class of schedulers is unrealistically powerful. This paper studies a strictly coarser notion of bisimilarity, which still enjoys these properties in the context of realistic subclasses of schedulers: Trace...

  12. Assessment and realistic mathematics education

    NARCIS (Netherlands)

    Heuvel-Panhuizen, M.H.A.M. van den

    1996-01-01

    This book describes the consequences of Realistic Mathematics Education (RME) for assessing students’ understanding of mathematics in primary school. RME is the Dutch answer to the worldwide need to reform mathematics education. Changed ideas about mathematics as a school subject, its goals,

  13. Distributed Generation and Islanding – Study on Converter Modeling of PV Grid-Connected Systems under Islanding Phenomena

    OpenAIRE

    2010-01-01

    The technique to derive a dc-ac full bridge switching converter for a PV grid-connected system are proposed in this paper. An analysis of islanding phenomena due to load variations of R and RLC connections can be easily derived by using the state-space averaging technique and the piecewise technique with feedback current control by setting up the duty cycle with sinusoidal terms around constant value of 0.5. The solution of the two proposed models can be handled via MATLAB/SIMULINK in fast sp...

  14. True-to-Life? Realistic Fiction.

    Science.gov (United States)

    Jordan, Anne Devereaux

    1995-01-01

    Suggests that modern realistic fiction for young readers is intensely moralistic and directive at the spoken and unspoken behest of the adults who write, select, and buy that literature. Discusses moral tales, early realistic fiction, modern realistic fiction, and choosing realistic fiction. (RS)

  15. True-to-Life? Realistic Fiction.

    Science.gov (United States)

    Jordan, Anne Devereaux

    1995-01-01

    Suggests that modern realistic fiction for young readers is intensely moralistic and directive at the spoken and unspoken behest of the adults who write, select, and buy that literature. Discusses moral tales, early realistic fiction, modern realistic fiction, and choosing realistic fiction. (RS)

  16. Statistical analysis of simulation-generated time series : Systolic vs. semi-systolic correlation on the Connection Machine

    NARCIS (Netherlands)

    Dontje, T.; Lippert, Th.; Petkov, N.; Schilling, K.

    1992-01-01

    Autocorrelation becomes an increasingly important tool to verify improvements in the state of the simulational art in Latice Gauge Theory. Semi-systolic and full-systolic algorithms are presented which are intensively used for correlation computations on the Connection Machine CM-2. The semi-systoli

  17. Statistical analysis of simulation-generated time series : Systolic vs. semi-systolic correlation on the Connection Machine

    NARCIS (Netherlands)

    Dontje, T.; Lippert, Th.; Petkov, N.; Schilling, K.

    1992-01-01

    Autocorrelation becomes an increasingly important tool to verify improvements in the state of the simulational art in Latice Gauge Theory. Semi-systolic and full-systolic algorithms are presented which are intensively used for correlation computations on the Connection Machine CM-2. The

  18. Realist Criminology and its Discontents

    Directory of Open Access Journals (Sweden)

    Simon Winlow

    2016-09-01

    Full Text Available Critical criminology must move beyond twentieth-century empiricist and idealist paradigms because the concepts and research programmes influenced by these paradigms are falling into obsolescence. Roger Matthews’ recent work firmly advocates this position and helps to set the ball rolling. Here we argue that Matthews’ attempt to use critical realist thought to move Left Realism towards an advanced position can help to put criminology on a sound new footing. However, before this becomes possible numerous philosophical and theoretical issues must be ironed out. Most importantly, critical criminology must avoid political pragmatism and adopt a more critical stance towards consumer culture’s spectacle. A searching analysis of these issues suggests that, ultimately, criminology is weighed down with obsolete thinking to such an extent that to remain intellectually relevant it must move beyond both Left Realism and Critical Realism to construct a new ultra-realist position.

  19. Assessment and realistic mathematics education

    OpenAIRE

    Heuvel-Panhuizen, M.H.A.M. van den

    1996-01-01

    This book describes the consequences of Realistic Mathematics Education (RME) for assessing students’ understanding of mathematics in primary school. RME is the Dutch answer to the worldwide need to reform mathematics education. Changed ideas about mathematics as a school subject, its goals, ideas about teaching and learning mathematics, require new forms of assessment. Within RME this means a preference for observation and individual interviews. However, written tests have not been abandoned...

  20. Changes in Functional Connectivity Associated with Direct Training and Generalization Effects of a Theory-Based Generative Naming Treatment

    Directory of Open Access Journals (Sweden)

    Swathi Kiran

    2014-04-01

    Nine PWA improved on the trained abstract words; seven PWA also showed generalization to concrete words in the same context-category. The region with the highest node degree in the trained abstract network across PWA was left inferior frontal gyrus pars triangularis (L IFGtri; while the highest node degree in the generalized concrete network was left precentral gyrus. Regions that showed increased connectivity for both training and generalization included L IFGtri, right middle frontal gyrus (MFG, and bilateral angular gyrus. Regions that showed increased connectivity regardless of whether or not treatment was given and whether or not treatment was successful included left MFG and bilateral superior frontal gyrus. Additionally, PWA who generalized showed more left than right hemisphere changes in both abstract and concrete networks; while PWA who improved on the trained abstract words, but did not generalize to concrete words showed more left than right hemisphere changes for the abstract network, but more right than left hemisphere changes for the concrete network. These results suggest that (a direct training and generalization are tapping into similar neural mechanisms, and (b changes in the left hemisphere coincide with better treatment outcomes.

  1. Generating a New Higher-Dimensional Ultra-Short Pulse System: Lie-Algebra Valued Connection and Hidden Structural Symmetries

    Institute of Scientific and Technical Information of China (English)

    Hermann T. Tchokouansi; Victor K. Kuetche; Abbagari Souleymanou; Thomas B. Bouetou; Timoleon C. Kofane

    2012-01-01

    We carry out the hidden structural symmetries embedded within a system comprising ultra-short pulses which propagate in optical nonlinear media. Based upon the Wahlquist Estabrook approach, we construct the Lie-algebra valued connections associated to the previous symmetries while deriving their corresponding Lax-pairs, which are particularly useful in soliton theory. In the wake of previous results, we extend the above prolongation scheme to higher-dimensional systems from which a new (2 + l)-dimensional ultra-short pulse equation is unveiled along with its inverse scattering formulation, the application of which are straightforward in nonlinear optics where an additional propagating dimension deserves some attention.%We carry out the hidden structural symmetries embedded within a system comprising ultra-short pulses which propagate in optical nonlinear media.Based upon the Wahlquist Estabrook approach,we construct the Liealgebra valued connections associated to the previous symmetries while deriving their corresponding Lax-pairs,which are particularly useful in soliton theory.In the wake of previous results,we extend the above prolongation scheme to higher-dimensional systems from which a new (2+ 1)-dimensional ultra-short pulse equation is unveiled along with its inverse scattering formulation,the application of which are straightforward in nonlinear optics where an additional propagating dimension deserves some attention.

  2. Coordinated Control of Superconducting Fault Current Limiter and Superconducting Magnetic Energy Storage for Transient Performance Enhancement of Grid-Connected Photovoltaic Generation System

    Directory of Open Access Journals (Sweden)

    Lei Chen

    2017-01-01

    Full Text Available In regard to the rapid development of renewable energy sources, more and more photovoltaic (PV generation systems have been connected to main power networks, and it is critical to enhance their transient performance under short-circuit faults conditions. This paper proposes and studies the coordinated control of a flux-coupling-type superconducting fault current limiter (SFCL and a superconducting magnetic energy storage (SMES, to improve the fault ride through (FRT capability and smooth the power fluctuation of a grid-connected PV generation system. Theoretical analyses of the device structure, operating principle and control strategy are conducted, and a detailed simulation model of 100 kW class PV generation system is built in MATLAB/SIMULINK. During the simulations of the symmetrical and asymmetrical faults, the maximum power point tracking (MPPT control is disabled, and four different cases including without auxiliary, with SFCL, with SMES, and with SFCL-SMES, are compared. From the demonstrated results, the combination of without MPPT and with SFCL-SMES can more efficiently improve the point of common coupling (PCC voltage sag, inhibit the DC-link overvoltage and alleviate the power fluctuation. Finally, a preliminary parameter optimization method is suggested for the SFCL and the SMES, and it is helpful to promote their future application in the real PV projects.

  3. Functional connectivity associated with hand shape generation: Imitating novel hand postures and pantomiming tool grips challenge different nodes of a shared neural network.

    Science.gov (United States)

    Vingerhoets, Guy; Clauwaert, Amanda

    2015-09-01

    Clinical research suggests that imitating meaningless hand postures and pantomiming tool-related hand shapes rely on different neuroanatomical substrates. We investigated the BOLD responses to different tasks of hand posture generation in 14 right handed volunteers. Conjunction and contrast analyses were applied to select regions that were either common or sensitive to imitation and/or pantomime tasks. The selection included bilateral areas of medial and lateral extrastriate cortex, superior and inferior regions of the lateral and medial parietal lobe, primary motor and somatosensory cortex, and left dorsolateral prefrontal, and ventral and dorsal premotor cortices. Functional connectivity analysis revealed that during hand shape generation the BOLD-response of every region correlated significantly with every other area regardless of the hand posture task performed, although some regions were more involved in some hand postures tasks than others. Based on between-task differences in functional connectivity we predict that imitation of novel hand postures would suffer most from left superior parietal disruption and that pantomiming hand postures for tools would be impaired following left frontal damage, whereas both tasks would be sensitive to inferior parietal dysfunction. We also unveiled that posterior temporal cortex is committed to pantomiming tool grips, but that the involvement of this region to the execution of hand postures in general appears limited. We conclude that the generation of hand postures is subserved by a highly interconnected task-general neural network. Depending on task requirements some nodes/connections will be more engaged than others and these task-sensitive findings are in general agreement with recent lesion studies.

  4. A reduced switch count UPF power conditioner for grid connected variable speed wind energy conversion system employing PM generators: a simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Raju, A.B.; Fernandes, B.G.; Chatterjee, K. [Indian Institute of Technology, Mumbai (India). Dept. of Electrical Engineering

    2004-07-01

    In this paper, modelling and simulation of a grid connected variable speed wind energy conversion system (VSWECS) with reduced switch count power converter is presented. The system consists of a permanent magnet synchronous generator (PMSG), two-pulse width modulated B-4 power converters and a maximum power point tracker (MPPT). Mathematical models of each element of the system are developed separately and are then integrated to simulate the whole system for various wind velocities. The complete system is simulated using MATLAB/SIMULINK and simulation results are presented. (author)

  5. Generating Units

    Data.gov (United States)

    Department of Homeland Security — Generating Units are any combination of physically connected generators, reactors, boilers, combustion turbines, and other prime movers operated together to produce...

  6. Hysteresis Current Controller Based Grid Connected Wind Energy Conversion System for Permanent Magnet Synchronous Generator and Quasi Z-Source Inverter Using Power Quality Improvement

    Directory of Open Access Journals (Sweden)

    E.Rajendran

    2013-10-01

    Full Text Available Wind energy is a leader area of application for variable-speed generators operating on the constant grid frequency. This paper depicts the power quality enhancement in wind power system using permanent magnet synchronous generator (PMSG and Quasi Z-source Inverter. The PMSG is connected to the power network by means of a quasi z-source inverter (qZSI. The PMSG are used by these technologies due to extraordinary characteristics such as a smaller amount weight and volume, superior performance, eradicate the gear box and no need of peripheral power in permanent magnet excitation. The PMSG overcome the induction generator and other generators, because of their splendid performances without take up the grid power. But Induction Generator always needs the grid connectionfor getting power to start. In this paper the quasi Z-source inverter is a present that is a novel topology conjugated from the traditional Z source Inverter. The qZSI inherits all the advantages of the ZSI, that is performs buck-boost, inversion and power control in wind energy conversion system (WECS Moreover, the proposed qZSI the matchless advantages of less component ratings and stable dc current from the source. All over boost control methods are built for the ZSI can be used by the qZSI .This Paper presents hysteresis current control technique for the quasi Z- source inverter.

  7. Realistic Real-Time Outdoor Rendering in Augmented Reality

    Science.gov (United States)

    Kolivand, Hoshang; Sunar, Mohd Shahrizal

    2014-01-01

    Realistic rendering techniques of outdoor Augmented Reality (AR) has been an attractive topic since the last two decades considering the sizeable amount of publications in computer graphics. Realistic virtual objects in outdoor rendering AR systems require sophisticated effects such as: shadows, daylight and interactions between sky colours and virtual as well as real objects. A few realistic rendering techniques have been designed to overcome this obstacle, most of which are related to non real-time rendering. However, the problem still remains, especially in outdoor rendering. This paper proposed a much newer, unique technique to achieve realistic real-time outdoor rendering, while taking into account the interaction between sky colours and objects in AR systems with respect to shadows in any specific location, date and time. This approach involves three main phases, which cover different outdoor AR rendering requirements. Firstly, sky colour was generated with respect to the position of the sun. Second step involves the shadow generation algorithm, Z-Partitioning: Gaussian and Fog Shadow Maps (Z-GaF Shadow Maps). Lastly, a technique to integrate sky colours and shadows through its effects on virtual objects in the AR system, is introduced. The experimental results reveal that the proposed technique has significantly improved the realism of real-time outdoor AR rendering, thus solving the problem of realistic AR systems. PMID:25268480

  8. Realistic real-time outdoor rendering in augmented reality.

    Science.gov (United States)

    Kolivand, Hoshang; Sunar, Mohd Shahrizal

    2014-01-01

    Realistic rendering techniques of outdoor Augmented Reality (AR) has been an attractive topic since the last two decades considering the sizeable amount of publications in computer graphics. Realistic virtual objects in outdoor rendering AR systems require sophisticated effects such as: shadows, daylight and interactions between sky colours and virtual as well as real objects. A few realistic rendering techniques have been designed to overcome this obstacle, most of which are related to non real-time rendering. However, the problem still remains, especially in outdoor rendering. This paper proposed a much newer, unique technique to achieve realistic real-time outdoor rendering, while taking into account the interaction between sky colours and objects in AR systems with respect to shadows in any specific location, date and time. This approach involves three main phases, which cover different outdoor AR rendering requirements. Firstly, sky colour was generated with respect to the position of the sun. Second step involves the shadow generation algorithm, Z-Partitioning: Gaussian and Fog Shadow Maps (Z-GaF Shadow Maps). Lastly, a technique to integrate sky colours and shadows through its effects on virtual objects in the AR system, is introduced. The experimental results reveal that the proposed technique has significantly improved the realism of real-time outdoor AR rendering, thus solving the problem of realistic AR systems.

  9. Realistic real-time outdoor rendering in augmented reality.

    Directory of Open Access Journals (Sweden)

    Hoshang Kolivand

    Full Text Available Realistic rendering techniques of outdoor Augmented Reality (AR has been an attractive topic since the last two decades considering the sizeable amount of publications in computer graphics. Realistic virtual objects in outdoor rendering AR systems require sophisticated effects such as: shadows, daylight and interactions between sky colours and virtual as well as real objects. A few realistic rendering techniques have been designed to overcome this obstacle, most of which are related to non real-time rendering. However, the problem still remains, especially in outdoor rendering. This paper proposed a much newer, unique technique to achieve realistic real-time outdoor rendering, while taking into account the interaction between sky colours and objects in AR systems with respect to shadows in any specific location, date and time. This approach involves three main phases, which cover different outdoor AR rendering requirements. Firstly, sky colour was generated with respect to the position of the sun. Second step involves the shadow generation algorithm, Z-Partitioning: Gaussian and Fog Shadow Maps (Z-GaF Shadow Maps. Lastly, a technique to integrate sky colours and shadows through its effects on virtual objects in the AR system, is introduced. The experimental results reveal that the proposed technique has significantly improved the realism of real-time outdoor AR rendering, thus solving the problem of realistic AR systems.

  10. How do we decide what to do? Resting-state connectivity patterns and components of self-generated thought linked to the development of more concrete personal goals.

    Science.gov (United States)

    Medea, Barbara; Karapanagiotidis, Theodoros; Konishi, Mahiko; Ottaviani, Cristina; Margulies, Daniel; Bernasconi, Andrea; Bernasconi, Neda; Bernhardt, Boris C; Jefferies, Elizabeth; Smallwood, Jonathan

    2016-07-21

    Human cognition is not limited to the available environmental input but can consider realities that are different to the here and now. We describe the cognitive states and neural processes linked to the refinement of descriptions of personal goals. When personal goals became concrete, participants reported greater thoughts about the self and the future during mind-wandering. This pattern was not observed for descriptions of TV programmes. Connectivity analysis of participants who underwent a resting-state functional magnetic resonance imaging scan revealed neural traits associated with this pattern. Strong hippocampal connectivity with ventromedial pre-frontal cortex was common to better-specified descriptions of goals and TV programmes, while connectivity between hippocampus and the pre-supplementary motor area was associated with individuals whose goals were initially abstract but became more concrete over the course of the experiment. We conclude that self-generated cognition that arises during the mind-wandering state can allow goals to be refined, and this depends on neural systems anchored in the hippocampus.

  11. 并网光伏电站置信容量评估%Capacity Credit Evaluation of Grid-Connected Photovoltaie Generation

    Institute of Scientific and Technical Information of China (English)

    方鑫; 郭强; 张东霞; 梁双

    2012-01-01

    To evaluate the capacity credit of photovoltaic (PV) generation is one of urgent problems to be considered when large-scale PV station is connected to traditional power grid. The capacity credit of PV generation is evaluated by the generation capacity that could be reduced in traditional power grid after the grid-connection of PV station. For this purpose, a new method for evaluating the capacity credit of PV generation is proposed. Firstly, an annual output fluctuating model of PV generation, in which the occurrence probabilities of different weather types, the maximum proportions of solar radiation under various whether conditions, the fluctuation radiation range due to clouds mask and the temperature coefficient random variation range are taken into account, is built; secondly, based on sequential Monte-Carlo simulation, a method to calculate generation reliability of power grid is put forward and its objective function is established based on the loss of load expectation (LOLE) before and after the grid-connection of PV station, and then the particle swarm optimization is utilized to search optimal combination of traditional generation sets to make the generation reliability level of power grid conforming with that before the grid-connection of PV station. Both correctness and effectiveness of the proposed model and algorithm are verified by simulation results of IEEE-RTS79 system..%衡量光伏发电的置信容量是大规模光伏电站接入电网时需要考虑的问题之一.以光伏发电接入后系统可以减少的发电容量来评估光伏发电的置信容量,建立了考虑不同天气类型概率、最大辐射强度、云遮波动以及温度系数波动的年光伏出力波动模型.提出了基于序贯蒙特卡罗仿真的电力系统发电可靠性的计算方法,并以光伏发电接入前后的系统电力不足期望(loss of load expectation,LOLE)为基础,建立了目标函数,并用粒子群优化算法搜索光伏发电接入后系

  12. Design of DC-DC Converter and its Control for a Wind Generation System Connected to an Isolated Load

    Directory of Open Access Journals (Sweden)

    Carlos A. Ramírez Gómez

    2013-11-01

    Full Text Available A method to design a Buck converter and its control, which are associated to a wind generation system that is feeding an isolated load, is presented in this paper. To design the converter a Thevenin equivalent is deduced, which represents the behavior of the wind turbine, the permanent magnet synchronous generator, and the rectifier. The design of the converter elements guarantees input/output voltages and inductor current ripples of 5 % or less. The output voltage control is developed with a proportional-integral-derivative controller and as design criteria a damping of 0,707 and cutoff frequency of 1/5 converter commutation frequency are selected. The designed controller regulates the output voltage faced load perturbations and wind speed variations. 

  13. An Optimized Combination of a Large Grid Connected PV System along with Battery Cells and a Diesel Generator

    OpenAIRE

    2016-01-01

    Environmental, economical and technical benefits of photovoltaic (PV) systems make them to be used in many countries. The main characteristic of PV systems is the fluctuations of their output power. Hence, high penetration of PV systems into electric network could be detrimental to overall system performance. Furthermore, the fluctuations in the output power of PV systems make it difficult to predict their output, and to consider them in generation planning of the units. The main objective of...

  14. 太阳能光伏发电并网模拟装置的研究%Research on simulated devices for photovoltaic grid-connected generation system

    Institute of Scientific and Technical Information of China (English)

    彭其泽; 张全柱

    2012-01-01

    On the standpoint of energy conservation and emission reduction, one device simulating the photovoltaic grid-connected generation system based on SPWM was designed in the paper. And DC/AC inverter could transduce efficiently direct current to alternating current. The MCU (micro-control-unit), in this system could achieve the control method for maximum-power-point and tracking for frequency and phase. Moreover, the MCU could implement PWM (plus-width modulating) through programming. The system showed clearly the whole photovoltaic grid-connected generation system using simulated methods and ways.%从节能减排的角度出发,设计了一种基于SPWM技术的光伏并网发电模拟装置,DC/AC逆变可以有效地进行直流至交流的转换.系统通过单片机编程的方式实现了最大功率点控制、频率和相位的跟踪.同时单片机还能通过编程方式实现PWM脉冲宽度调制.本系统最大的特点是用模拟的方式简明地介绍了整个光伏并网发电系统.

  15. Simulating realistic enough patient records.

    Science.gov (United States)

    Cunningham, James; Ainsworth, John

    2015-01-01

    Information systems for storing, managing and manipulating electronic medical records must place an emphasis on maintaining the privacy and security of those records. Though the design, development and testing of such systems also requires the use of data, the developers of these systems, rarely also their final end users, are unlikely to have ethical or governance approval to use real data. Alternative test data is commonly either randomly produced or taken from carefully anonymised subsets of records. In both cases there are potential shortcomings that can impact on the quality of the product being developed. We have addressed these shortcomings with a tool and methodology for efficiently simulating large amounts of realistic enough electronic patient records which can underpin the development of data-centric electronic healthcare systems.

  16. Realist RCTs of complex interventions - an oxymoron.

    Science.gov (United States)

    Marchal, Bruno; Westhorp, Gill; Wong, Geoff; Van Belle, Sara; Greenhalgh, Trisha; Kegels, Guy; Pawson, Ray

    2013-10-01

    Bonell et al. discuss the challenges of carrying out randomised controlled trials (RCTs) to evaluate complex interventions in public health, and consider the role of realist evaluation in enhancing this design (Bonell, Fletcher, Morton, Lorenc, & Moore, 2012). They argue for a "synergistic, rather than oppositional relationship between realist and randomised evaluation" and that "it is possible to benefit from the insights provided by realist evaluation without relinquishing the RCT as the best means of examining intervention causality." We present counter-arguments to their analysis of realist evaluation and their recommendations for realist RCTs. Bonell et al. are right to question whether and how (quasi-)experimental designs can be improved to better evaluate complex public health interventions. However, the paper does not explain how a research design that is fundamentally built upon a positivist ontological and epistemological position can be meaningfully adapted to allow it to be used from within a realist paradigm. The recommendations for "realist RCTs" do not sufficiently take into account important elements of complexity that pose major challenges for the RCT design. They also ignore key tenets of the realist evaluation approach. We propose that the adjective 'realist' should continue to be used only for studies based on a realist philosophy and whose analytic approach follows the established principles of realist analysis. It seems more correct to call the approach proposed by Bonell and colleagues 'theory informed RCT', which indeed can help in enhancing RCTs. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Realist Stronghold in the Land of Thucydides? - Appraising and Resisting a Realist Tradition in Greece

    Directory of Open Access Journals (Sweden)

    Kyriakos Mikelis

    2015-10-01

    Full Text Available Given the integration of the discipline of International Relations in Greece into the global discipline since a few decades, the article addresses the reflection of the ‘realism in and for the globe’ question to this specific case. Although the argument doesn’t go as far as to ‘recover’ forgotten IR theorists or self-proclaimed realists, a geopolitical dimension of socio-economic thought during interwar addressed concerns which could be related to the intricacies of realpolitik. Then again at current times, certain scholars have been eager to maintain a firm stance in favor of realism, focusing on the work of ancient figures, especially Thucydides or Homer, and on questions of the offensive-defensive realism debate as well as on the connection with the English School, while others have offered fruitful insights matching the broad constructivist agenda. Overall, certain genuine arguments have appeared, reflecting diversified views about sovereignty and its function or mitigation.

  18. A natural connection between neutrino mass generation and the lightness of a next-to-minimal supersymmetric Standard Model pseudoscalar

    Indian Academy of Sciences (India)

    Debottam Das; Asmaa Abada; Gautam Bhattacharyya; Cédric Weiland

    2012-10-01

    One of the attractive properties of the NMSSM is that it can accommodate a light pseudoscalar of order 10 GeV. However, such scenarios are constrained by several experimental results, especially those related to the fermionic decays of the pseudoscalar. In this work, extending the NMSSM field content by two gauge singlets, with lepton number +1 and −1, we generate neutrino masses via the inverse see-saw mechanism at one hand and on the other hand a very light pseudoscalar becomes experimentally viable by having dominant invisible decay channels which help it to evade the existing bounds.

  19. Study of airflow during respiratory cycle in semi-realistic model of human tracheobronchial tree

    Science.gov (United States)

    Elcner, Jakub; Zaremba, M.; Maly, M.; Jedelsky, J.; Lizal, F.; Jicha, M.

    2016-06-01

    This article deals with study of airflow under breathing process, which is characteristic by unsteady behavior. Simulations provided by computational fluid dynamics (CFD) was compared with experiments performed on similar geometry of human upper airways. This geometry was represented by mouth cavity of realistic shape connected to an idealized tracheobronchial tree up to fourth generation of branching. Commercial CFD software Star-CCM+ was used to calculate airflow inside investigated geometry and method of Reynolds averaging of Navier-Stokes equations was used for subscribing the turbulent behavior through model geometry. Conditions corresponding to resting state were considered. Comparisons with experiments were provided on several points through trachea and bronchial tree and results with respect to inspiratory and respiratory part of breathing cycle was discussed.

  20. 光伏发电并网系统相量模型建模研究%Research on Phasor Model of Grid Connection PV Generation System

    Institute of Scientific and Technical Information of China (English)

    邱革非; 张春刚; 仲泽坤; 字杨

    2015-01-01

    A grid connection photovoltaic power generation system model is built in this paper.By this model, power characters of power grid which is connected with PV generation systems can be researched without igno-rance of the characters of PV generation system.Based on phasor analyzing method,PV generation system with power output controlling unit is built in detail,so that it can reflect actual controlling characteristics of PV system truthfully.Compared with existing grid connection PV models,it has the advantage of faster simulation,which can be applied to power system researches on power transferring and controlling characteristics of power system based on phasor analysis.%建立了一个既适用于电力系统网络功率分析,同时也能够在仿真过程中较为细致地反映光伏发电系统实际并网运行特性的并网光伏发电系统模型。文中以相量分析为基础对包含功率控制单元在内的发电系统进行了较为详细的相量建模,使得所建立的发电系统模型能够更为真实地体现光伏发电系统功率输出及控制特性,且由于模型系针对电力系统能量关系的分析研究而建,相较于现有光伏发电并网模型具备仿真速度快的优势,弥补了现存模型存在的缺点,可以方便地融合到以相量分析方法为基础的电力系统运行及控制特性相关研究中。

  1. An Adaptive Quadrature Signal Generation Based Single-Phase Phase-Locked Loop for Grid-Connected Applications

    DEFF Research Database (Denmark)

    Golestan, Saeed; Guerrero, Josep M.; Abusorrah, Abdullah

    2017-01-01

    The quadrature signal generation based phase-locked loops (QSG-PLLs) are highly popular for synchronization purposes in single-phase systems. The main difference among these PLLs often lies in the technique they use for creating the fictitious quadrature component. One of the easiest QSG approaches...... is delaying the original single-phase signal by a quarter of a cycle. The PLL with such QSG technique is often called the transfer delay based PLL (TD-PLL). The TD-PLL benefits from a simple structure, rather fast dynamic response, and a good detection accuracy when the grid frequency is at its nominal value......, but it suffers from a phase offset error and double frequency oscillatory error in the estimated phase and frequency in the presence of frequency drifts. In this paper, a simple yet effective approach to remove the aforementioned errors of the TD-PLL is proposed. The resultant PLL structure is called...

  2. Eigenvalue Analysis of a Network Connected to a Wind Turbine Implemented with a Doubly-Fed Induction Generator (DFIG

    Directory of Open Access Journals (Sweden)

    M. Jazaeri

    2012-10-01

    Full Text Available Recently, the growing integration of wind energy into power networks has had a significant impact on power systemstability. Amongst types of large capacity wind turbines (WTs, doubly-fed induction generator (DFIG wind turbinesrepresent an important percentage. This paper attemps to study the impact of DFIG wind turbines on the powersystem stability and dynamics by modeling all components of a case study system (CSS. Modal analysis is usedfor the study of the dynamic stability of the CSS. The system dynamics are studied by examining the eigenvaluesof the matrix system of the case study and the impact of all parameters of the CSS are studied in normal,subsynchronous and super-synchronous modes. The results of the eigenvalue analysis are verified by usingdynamic simulation software. The results show that each of the electrical and mechanical parameters of the CSSaffect specific eigenvalues.

  3. Transient analysis of a grid connected wind driven induction generator using a real-time simulation platform

    Energy Technology Data Exchange (ETDEWEB)

    Ouhrouche, Mohand [Department of Applied Sciences, University of Quebec at Chicoutimi, Quebec, G7H2B1 (Canada)

    2009-03-15

    Due to its simple construction, ruggedness and low cost, the induction generator driven by a wind turbine and feeding power to the grid appears to be an attractive solution to the problem of growing energy demand in the context of environmental issues. This paper investigates the integration of such a system into the main utility using RT-Lab trademark (Trademark of Opal-RT Technologies) software package running on a simple off-the-shelf PC. This real-time simulation platform is now adopted by many high-tech industries as a real-time laboratory package for rapid control prototyping and for Hardware-in-the-Loop applications. Real-time digital simulation results obtained during contingencies, such as islanding and unbalanced faults are presented and analysed. (author)

  4. Helping With All Your Heart: Realistic Heart Stimulus and Compliance With an Organ Donation Request.

    Science.gov (United States)

    Jacob, Céline; Guéguen, Nicolas

    2015-01-01

    Pictures and images are important aspects in fundraising advertising and could generate more donations. In two experimental studies, we examined the effect of various pictures of hearts on compliance with a request for organ donations. The solicitor wore a white tee shirt where various forms of hearts were printed: symbolic versus realistic (first experiment), none versus symbolic versus realistic (second experiment). Results showed that more compliance was found in the realistic heart experimental condition whereas the symbolic heart form had no significant effect.

  5. Performance Evaluation of Realistic Vanet Using Traffic Light Scenario

    CERN Document Server

    Nidhi,

    2012-01-01

    Vehicular Ad-hoc Networks (VANETs) is attracting considerable attention from the research community and the automotive industry to improve the services of Intelligent Transportation System (ITS). As today's transportation system faces serious challenges in terms of road safety, efficiency, and environmental friendliness, the idea of so called "ITS" has emerged. Due to the expensive cost of deployment and complexity of implementing such a system in real world, research in VANET relies on simulation. This paper attempts to evaluate the performance of VANET in a realistic environment. The paper contributes by generating a real world road Map of JNU using existing Google Earth and GIS tools. Traffic data from a limited region of road Map is collected to capture the realistic mobility. In this work, the entire region has been divided into various smaller routes. The realistic mobility model used here considers the driver's route choice at the run time. It also studies the clustering effect caused by traffic lights...

  6. Realistic modeling of neurons and networks: towards brain simulation.

    Science.gov (United States)

    D'Angelo, Egidio; Solinas, Sergio; Garrido, Jesus; Casellato, Claudia; Pedrocchi, Alessandra; Mapelli, Jonathan; Gandolfi, Daniela; Prestori, Francesca

    2013-01-01

    Realistic modeling is a new advanced methodology for investigating brain functions. Realistic modeling is based on a detailed biophysical description of neurons and synapses, which can be integrated into microcircuits. The latter can, in turn, be further integrated to form large-scale brain networks and eventually to reconstruct complex brain systems. Here we provide a review of the realistic simulation strategy and use the cerebellar network as an example. This network has been carefully investigated at molecular and cellular level and has been the object of intense theoretical investigation. The cerebellum is thought to lie at the core of the forward controller operations of the brain and to implement timing and sensory prediction functions. The cerebellum is well described and provides a challenging field in which one of the most advanced realistic microcircuit models has been generated. We illustrate how these models can be elaborated and embedded into robotic control systems to gain insight into how the cellular properties of cerebellar neurons emerge in integrated behaviors. Realistic network modeling opens up new perspectives for the investigation of brain pathologies and for the neurorobotic field.

  7. Induction of Heat Resistance in Wheat Coleoptiles by 4-Hydroxybenzoic Acid: Connection with the Generation of Reactive Oxygen Species

    Directory of Open Access Journals (Sweden)

    Yastreb T.O.

    2012-08-01

    Full Text Available The effect of 4-hydroxybenzoic acid (4-HBA on resistance of coleoptiles of 4-day-old etiolated seedlings of wheat (Triticum aestivum L., cv. Elegiya to damaging heating (10 min at 43°C and possible dependence of this effect on changes in the activities of enzymes producing and scavenging reactive oxygen species (ROS were investigated. Treatment of coleoptiles with 10 μM 4-HBA resulted in enhancing of superoxide anion-radical generation and maintaining of hydrogen peroxide content there in. Increasing of the rate of ROS production was significantly suppressed by inhibitors of NADPH oxidase (α-naphthol and peroxidase (salicylhydroxamic acid. Under the influence of 4-HBA the activities of superoxide dismutase and apoplastic forms of peroxidase were increased. The activity of oxalate oxidase and catalase has not changed. Exogenous 4-HBA improved coleoptiles heat resistance and its effects were comparable with the influence of salicylic acid. Antioxidant agent BHT (butylhydroxytoluene, inhibitors of NADPH oxidase and peroxidase significantly reduced the increasing of wheat coleoptiles heat resistance, caused by 4-HBA action. It was concluded that 4-HBA influence on coleoptiles heat resistance is realized with the ROS mediation.

  8. Inverter systems with intermediate current cycle connecting photovoltaic generators to grids; Wechselrichtersysteme mit Stromzwischenkreis zur Netzanbindung von Photovoltaik-Generatoren

    Energy Technology Data Exchange (ETDEWEB)

    Sahan, Benjamin

    2010-11-13

    Power electronic converters for adapting the volatile photovoltaic dc generators to the relatively stiff requirements of the distribution and transmission grids are rapidly gaining importance. The inverter technology is principally based on two types of concepts: Voltage Source Inverters and Current Source Inverters. Especially self-commutated Current Source Inverters did not achieve significance until today. This raises the question of the basic criteria which could either prevent the use of those inverters or even promote them. The two basic concepts are first subjected to a systematic comparison. For this purpose dimensionless benchmark factors are used. At the same time different exemplarily setups are described and documented by measurements. A Current Source Inverter system for integration into high-voltage PV modules is presented, which features a single-stage approach and thus achieves a very high efficiency and compact dimensions. Moreover, new types of inverter topology are considered with indirect (controlled) current dc links. Combining low frequency with only a very few high frequency switches opens up new possibilities for power electronics design, e.g. the use of Normally-on SiC-JFETs. This, however, contradicts the common paradigm to only use normally-off switches in power electronics. Apart from this, new approaches for the use of robust and cost efficient thyristor circuits are presented. These are enabled to fulfill the new grid codes even with injected leading reactive power into the electricity grid which contributes to its stability. (orig.)

  9. Transistor Effect in Improperly Connected Transistors.

    Science.gov (United States)

    Luzader, Stephen; Sanchez-Velasco, Eduardo

    1996-01-01

    Discusses the differences between the standard representation and a realistic representation of a transistor. Presents an experiment that helps clarify the explanation of the transistor effect and shows why transistors should be connected properly. (JRH)

  10. Optimal energy management system in grid connected Microgrid integrated with distributed generation by using the multi-period artificial bee colony

    Directory of Open Access Journals (Sweden)

    Fatemeh Azarinejadian

    2014-10-01

    Full Text Available Presenting proper and efficient energy management system (EMS in the Microgrids (MG is an important issue for gaining assurance to optimize energy usage based on price preference and system technical constraints. Nowadays by utilizing renewable energy resources and energy storage systems in MG, in addition to reducing the pollution caused by fossil fuels, the safety and power system reliability can also be improved. The proposed algorithm to implement an EMS shall increase the MG ability in both islanded and grid connected operating mode to supply non-responsive load demands from the economic points of view. Implementing EMS over the MG of Institute de Recerca on Energia de Catalunya (IREC based on artificial bee colony (ABC optimization approach to economic dispatch between various generation units, considering their offer price is main novelty of this paper. The obtained results from the proposed algorithm when compared with the EMS algorithm based on mixed integer non-linear programming (MINLP demonstrate the reduction of about 18% of the total generation; and it also improves the efficiency of the demand/ generation side management.

  11. Object detection approach using generative sparse, hierarchical networks with top-down and lateral connections for combining texture/color detection and shape/contour detection

    Energy Technology Data Exchange (ETDEWEB)

    Paiton, Dylan M.; Kenyon, Garrett T.; Brumby, Steven P.; Schultz, Peter F.; George, John S.

    2016-10-25

    An approach to detecting objects in an image dataset may combine texture/color detection, shape/contour detection, and/or motion detection using sparse, generative, hierarchical models with lateral and top-down connections. A first independent representation of objects in an image dataset may be produced using a color/texture detection algorithm. A second independent representation of objects in the image dataset may be produced using a shape/contour detection algorithm. A third independent representation of objects in the image dataset may be produced using a motion detection algorithm. The first, second, and third independent representations may then be combined into a single coherent output using a combinatorial algorithm.

  12. Object detection approach using generative sparse, hierarchical networks with top-down and lateral connections for combining texture/color detection and shape/contour detection

    Energy Technology Data Exchange (ETDEWEB)

    Paiton, Dylan M.; Kenyon, Garrett T.; Brumby, Steven P.; Schultz, Peter F.; George, John S.

    2015-07-28

    An approach to detecting objects in an image dataset may combine texture/color detection, shape/contour detection, and/or motion detection using sparse, generative, hierarchical models with lateral and top-down connections. A first independent representation of objects in an image dataset may be produced using a color/texture detection algorithm. A second independent representation of objects in the image dataset may be produced using a shape/contour detection algorithm. A third independent representation of objects in the image dataset may be produced using a motion detection algorithm. The first, second, and third independent representations may then be combined into a single coherent output using a combinatorial algorithm.

  13. Object detection approach using generative sparse, hierarchical networks with top-down and lateral connections for combining texture/color detection and shape/contour detection

    Science.gov (United States)

    Paiton, Dylan M.; Kenyon, Garrett T.; Brumby, Steven P.; Schultz, Peter F.; George, John S.

    2016-10-25

    An approach to detecting objects in an image dataset may combine texture/color detection, shape/contour detection, and/or motion detection using sparse, generative, hierarchical models with lateral and top-down connections. A first independent representation of objects in an image dataset may be produced using a color/texture detection algorithm. A second independent representation of objects in the image dataset may be produced using a shape/contour detection algorithm. A third independent representation of objects in the image dataset may be produced using a motion detection algorithm. The first, second, and third independent representations may then be combined into a single coherent output using a combinatorial algorithm.

  14. Generations.

    Science.gov (United States)

    Chambers, David W

    2005-01-01

    Groups naturally promote their strengths and prefer values and rules that give them an identity and an advantage. This shows up as generational tensions across cohorts who share common experiences, including common elders. Dramatic cultural events in America since 1925 can help create an understanding of the differing value structures of the Silents, the Boomers, Gen Xers, and the Millennials. Differences in how these generations see motivation and values, fundamental reality, relations with others, and work are presented, as are some applications of these differences to the dental profession.

  15. On Grid-connected of Distributed Generation in Smart Distribution Grid%智能配电网中分布式电源并网的思考

    Institute of Scientific and Technical Information of China (English)

    王淼; 董仲星; 刘宗歧

    2012-01-01

    智能配电网是统一坚强智能电网的重要组成,是智能电网中连接主网和面向用户供电的重要组成部分。而接纳大规模分布式电源的灵活运行和操作,是智能配电网建成的重要特征之一。本文综合阐述和分析了分布式电源并网的相关内容,介绍了分布式发电技术及相关特性,结合具体算例,重点分析了并网带来的影响,指出智能配电网优化规划的问题和主要研究思路和方法,综合分析分布式并网的保护与控制,为未来分布式电源并网的深入研究和工程实践做铺垫。%Smart distribution grid is an important part of smart grid, which is the connection of main network and customers in smart grid. The acceptation of large-scale distributed generationrs is one of the symbols of the success of smart distribution network. This paper describes the related content about the distributed generation and its parallel operation on power system. Features of distributed generation are raised at first. Then example, the paper focuses on the influence caused by distributed generation synchronization. The technologies and ideas about smart distribution network planning with DGs are discussed in detail, as well as the protection of the parallel operation. This indeed sheds light on unified smart grid construction and its futuristic research of smart grid with distributed generation.

  16. Analysis of a modular generator for high-voltage, high-frequency pulsed applications, using low voltage semiconductors (series connected step-up (1:10) transformers

    Science.gov (United States)

    Redondo, L. M.; Fernando Silva, J.; Margato, E.

    2007-03-01

    This article discusses the operation of a modular generator topology, which has been developed for high-frequency (kHz), high-voltage (kV) pulsed applications. The proposed generator uses individual modules, each one consisting of a pulse circuit based on a modified forward converter, which takes advantage of the required low duty cycle to operate with a low voltage clamp reset circuit for the step-up transformer. This reduces the maximum voltage on the semiconductor devices of both primary and secondary transformer sides. The secondary winding of each step-up transformer is series connected, delivering a fraction of the total voltage. Each individual pulsed module is supplied via an isolation transformer. The assembled modular laboratorial prototype, with three 5kV modules, 800V semiconductor switches, and 1:10 step-up transformers, has 80% efficiency, and is capable of delivering, into resistive loads, -15kV/1A pulses with 5μs width, 10kHz repetition rate, with less than 1μs pulse rise time. Experimental results for resistive loads are presented and discussed.

  17. A New Robust Decoupled Control of the Stator Active and Reactive Currents for Grid-Connected Doubly-Fed Induction Generators

    Directory of Open Access Journals (Sweden)

    Ahmad Bashar Ataji

    2016-03-01

    Full Text Available This paper addresses the grid-connected variable speed doubly-fed induction generator, and proposes a new decoupled control to replace the conventional decoupled active and reactive powers (P-Q control. The proposed decoupled control is based on decoupling the stator active and reactive currents, in contrast with the conventional decoupled P-Q control, which is based on decoupling the stator active and reactive powers by forcing the stator d- or q-voltage to zero. The proposed decoupled control has all the advantages of the conventional decoupled P-Q control such as constant switching frequency and robustness against slip angle inaccuracy, and it has some additional advantages: The proposed control requires less machine parameters; for the controller design, it requires the stator-to-rotor turns ratio only; for the online calculation, it does not requires any machine parameter. The proposed decoupled control is more flexible and robust since the control is independent of the grid voltage orientation. It is robust against variation in the grid voltage amplitude. Several experiments are carried out using a 1.1 kW doubly-fed induction generator (DFIG, and the results support the proposed decoupled control and demonstrate some of its advantages.

  18. Analysis of a modular generator for high-voltage, high-frequency pulsed applications, using low voltage semiconductors (series connected step-up (1:10) transformers.

    Science.gov (United States)

    Redondo, L M; Fernando Silva, J; Margato, E

    2007-03-01

    This article discusses the operation of a modular generator topology, which has been developed for high-frequency (kHz), high-voltage (kV) pulsed applications. The proposed generator uses individual modules, each one consisting of a pulse circuit based on a modified forward converter, which takes advantage of the required low duty cycle to operate with a low voltage clamp reset circuit for the step-up transformer. This reduces the maximum voltage on the semiconductor devices of both primary and secondary transformer sides. The secondary winding of each step-up transformer is series connected, delivering a fraction of the total voltage. Each individual pulsed module is supplied via an isolation transformer. The assembled modular laboratorial prototype, with three 5 kV modules, 800 V semiconductor switches, and 1:10 step-up transformers, has 80% efficiency, and is capable of delivering, into resistive loads, -15 kV1 A pulses with 5 micros width, 10 kHz repetition rate, with less than 1 micros pulse rise time. Experimental results for resistive loads are presented and discussed.

  19. Leadership research in healthcare: A realist review.

    Science.gov (United States)

    Lega, Federico; Prenestini, Anna; Rosso, Matilde

    2017-05-01

    Being largely considered a human right, healthcare needs leaders who are able to make choices and to set directions. Following the recommendations expressed by Gilmartin and D'Aunno's review and roadmap compiled in 2008, today, it is important to acknowledge researchers' contributions to outline this landscape. The realist review of 77 publications answered questions such as "what works, for whom, and in which circumstances" highlighting: the effectiveness and acceptance of transformational and collaborative approaches; professionalism, expertise, and good task delegation within operational teams; distributed leadership, relationships, and social responsibility at a systemic level. The relevancy and need of leadership development programs, framed within a wider strategy, emerged. Nonetheless, gaps still exist and require further investigation: particular needs in public vs. private contexts; professionals' and women's differentiating characters; generational gaps; associations between leadership and recruitment HR practices research; how (and if) leaders (should) influence the organizational culture and values; and developing countries specific challenges. Also, a greater proportion of relevant findings should be drawn by empirical and more rigorous studies. Finally, a major attention could be paid to interactions happening at the team, organizational, and systemic level among different leaders and among leaders, followers and external actors.

  20. 光伏并网发电实验系统设计%Design of experimental system for grid-connected photovoltaic power generation

    Institute of Scientific and Technical Information of China (English)

    刘佐濂; 杨汝; 何清平; 崔海霞

    2011-01-01

    设计开发了1套光伏并网发电实验系统.该系统由太阳能电池板及控制器、模拟负载、PC机和参数测量设备组成,系统可独立运行和模拟并网运行,控制器电路采用DC/DC/AC架构,实验装置可以测量系统的最大功率点跟踪能力、频率跟踪能力、逆变器的效率和逆变器的失真度等重要指标,具有二次开发功能,适合学生开展设计性实验.系统采用开放形式,直观性好,针对性强,结构原理清楚.%A experimental system for grid-connected photovoltaic power generation is designed. It consists of solar panels, simulating load, PC and a measuring equipment of parameter. The system can operate independently and simulate grid-connected operation. DC/DC/AC structure is applied to main control circuit. Some important indexes are measured by this experimental system, such as the capacities of maximum power point tracking and frequency tracking, the efficiency and the distortion of the inverter, etc. The secondary developing function of the system suits students to carry out the designing experiments. This system applies open form; there is good visuality, strong relevance and clear structure.

  1. Toward the M(F)-theory embedding of realistic free-fermion models

    Energy Technology Data Exchange (ETDEWEB)

    Berglund, P. [Univ. of California, Santa Barbara, CA (United States). Institute for Theoretical Physics; Ellis, J. [CERN, Geneva (Switzerland). Theory Division; Faraggi, A.E. [Univ. of Florida, Gainesville, FL (United States). Institute for Fundamental Theory] [and others

    1998-03-01

    We construct a Landau-Ginzburg model with the same data and symmetries as a Z{sub 2} x Z{sub 2} orbifold that corresponds to a class of realistic free-fermion models. Within the class of interest, we show that this orbifolding connects between different Z{sub 2} x Z{sub 2} orbifold models and connects with the mirror symmetry. Our work suggests that duality symmetries previously discussed in the context of specific M and F theory compactifications may be extended to the special Z{sub 2} x Z{sub 2} orbifold that characterizes realistic free-fermion models.

  2. Stability of realistic strange stars (RSS)

    CERN Document Server

    Bhowmick, S; Dey, M; Ray, S; Ray, R; Bhowmick, Siddhartha; Dey, Jishnu; Dey, Mira; Ray, Subharthi; Ray, Ranjan

    2001-01-01

    Strange stars (SS) calculated from a realistic equation of state (EOS) are very stable, for example under fast rotation but have a soft surface, on which ripples may occur when radiation is emitted close to it. We suggest this as a natural explanation of the fluctuations observed in the intensity profile of X-ray pulsars. In contrast, SS based on EOS derived from the bag models (Bag SS) are less stable against fast rotation and do not have a hard surface and cannot explain these ripples. There are other important differences between Bag SS and the SS, based on a realistic EOS, which we call realistic strange stars (RSS).

  3. Optimizing performance of hybrid FSO/RF networks in realistic dynamic scenarios

    Science.gov (United States)

    Llorca, Jaime; Desai, Aniket; Baskaran, Eswaran; Milner, Stuart; Davis, Christopher

    2005-08-01

    Hybrid Free Space Optical (FSO) and Radio Frequency (RF) networks promise highly available wireless broadband connectivity and quality of service (QoS), particularly suitable for emerging network applications involving extremely high data rate transmissions such as high quality video-on-demand and real-time surveillance. FSO links are prone to atmospheric obscuration (fog, clouds, snow, etc) and are difficult to align over long distances due the use of narrow laser beams and the effect of atmospheric turbulence. These problems can be mitigated by using adjunct directional RF links, which provide backup connectivity. In this paper, methodologies for modeling and simulation of hybrid FSO/RF networks are described. Individual link propagation models are derived using scattering theory, as well as experimental measurements. MATLAB is used to generate realistic atmospheric obscuration scenarios, including moving cloud layers at different altitudes. These scenarios are then imported into a network simulator (OPNET) to emulate mobile hybrid FSO/RF networks. This framework allows accurate analysis of the effects of node mobility, atmospheric obscuration and traffic demands on network performance, and precise evaluation of topology reconfiguration algorithms as they react to dynamic changes in the network. Results show how topology reconfiguration algorithms, together with enhancements to TCP/IP protocols which reduce the network response time, enable the network to rapidly detect and act upon link state changes in highly dynamic environments, ensuring optimized network performance and availability.

  4. Connected Traveler

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Alex

    2015-11-01

    The Connected Traveler project is a multi-disciplinary undertaking that seeks to validate potential for transformative transportation system energy savings by incentivizing efficient traveler behavior. This poster outlines various aspects of the Connected Traveler project, including market opportunity, understanding traveler behavior and decision-making, automation and connectivity, and a projected timeline for Connected Traveler's key milestones.

  5. Sotsialistlik realist Keskküla

    Index Scriptorium Estoniae

    1998-01-01

    Londonis 1998. a. ilmunud inglise kunstikriitiku Matthew Cullerne Bowni monograafias "Socialist Realist Painting" on eesti kunstnikest Enn Põldroos, Nikolai Kormashov, Ando Keskküla, Kormashovi ja Keskküla maalide reproduktsioonid

  6. Sotsialistlik realist Keskküla

    Index Scriptorium Estoniae

    1998-01-01

    Londonis 1998. a. ilmunud inglise kunstikriitiku Matthew Cullerne Bowni monograafias "Socialist Realist Painting" on eesti kunstnikest Enn Põldroos, Nikolai Kormashov, Ando Keskküla, Kormashovi ja Keskküla maalide reproduktsioonid

  7. Realistic Approach for Phasor Measurement Unit Placement

    DEFF Research Database (Denmark)

    Rather, Zakir Hussain; Chen, Zhe; Thøgersen, Paul

    2015-01-01

    This paper presents a realistic cost-effectivemodel for optimal placement of phasor measurement units (PMUs) for complete observability of a power system considering practical cost implications. The proposed model considers hidden or otherwise unaccounted practical costs involved in PMU...

  8. Electron percolation in realistic models of carbon nanotube networks

    Science.gov (United States)

    Simoneau, Louis-Philippe; Villeneuve, Jérémie; Rochefort, Alain

    2015-09-01

    The influence of penetrable and curved carbon nanotubes (CNT) on the charge percolation in three-dimensional disordered CNT networks have been studied with Monte-Carlo simulations. By considering carbon nanotubes as solid objects but where the overlap between their electron cloud can be controlled, we observed that the structural characteristics of networks containing lower aspect ratio CNT are highly sensitive to the degree of penetration between crossed nanotubes. Following our efficient strategy to displace CNT to different positions to create more realistic statistical models, we conclude that the connectivity between objects increases with the hard-core/soft-shell radii ratio. In contrast, the presence of curved CNT in the random networks leads to an increasing percolation threshold and to a decreasing electrical conductivity at saturation. The waviness of CNT decreases the effective distance between the nanotube extremities, hence reducing their connectivity and degrading their electrical properties. We present the results of our simulation in terms of thickness of the CNT network from which simple structural parameters such as the volume fraction or the carbon nanotube density can be accurately evaluated with our more realistic models.

  9. Towards an agential realist thinking of learning

    DEFF Research Database (Denmark)

    Plauborg, Helle

    2014-01-01

    This paper explores what can be understood by learning based on agential realist thinking. An agential realist thinking about learning is sensitive to the complexity that characterizes learning as a phenomenon. Thus, learning, from an agential realist perspective, is a dynamic and emergent phenom...... or a radical change in the sense of 'penny dropped'. For although learning processes that are not recognized as 'aha moments' do not call much attention to themselves, this is how they occur most often.......This paper explores what can be understood by learning based on agential realist thinking. An agential realist thinking about learning is sensitive to the complexity that characterizes learning as a phenomenon. Thus, learning, from an agential realist perspective, is a dynamic and emergent...... human, which means that it is not only the human and the discursive possessing empowerment in relation to learning; the non-human also is woven into - and makes constitutive difference to - human learning processes. An excerpt from a field note will be used to illustrate these mutual shaping processes...

  10. Realist synthesis: illustrating the method for implementation research

    Directory of Open Access Journals (Sweden)

    Rycroft-Malone Jo

    2012-04-01

    Full Text Available Abstract Background Realist synthesis is an increasingly popular approach to the review and synthesis of evidence, which focuses on understanding the mechanisms by which an intervention works (or not. There are few published examples of realist synthesis. This paper therefore fills a gap by describing, in detail, the process used for a realist review and synthesis to answer the question ‘what interventions and strategies are effective in enabling evidence-informed healthcare?’ The strengths and challenges of conducting realist review are also considered. Methods The realist approach involves identifying underlying causal mechanisms and exploring how they work under what conditions. The stages of this review included: defining the scope of the review (concept mining and framework formulation; searching for and scrutinising the evidence; extracting and synthesising the evidence; and developing the narrative, including hypotheses. Results Based on key terms and concepts related to various interventions to promote evidence-informed healthcare, we developed an outcome-focused theoretical framework. Questions were tailored for each of four theory/intervention areas within the theoretical framework and were used to guide development of a review and data extraction process. The search for literature within our first theory area, change agency, was executed and the screening procedure resulted in inclusion of 52 papers. Using the questions relevant to this theory area, data were extracted by one reviewer and validated by a second reviewer. Synthesis involved organisation of extracted data into evidence tables, theming and formulation of chains of inference, linking between the chains of inference, and hypothesis formulation. The narrative was developed around the hypotheses generated within the change agency theory area. Conclusions Realist synthesis lends itself to the review of complex interventions because it accounts for context as well as

  11. On the Quality of Wireless Network Connectivity

    CERN Document Server

    Dasgupta, Soura

    2011-01-01

    Despite intensive research in the area of network connectivity, there is an important category of problems that remain unsolved: how to measure the quality of connectivity of a wireless multi-hop network which has a realistic number of nodes, not necessarily large enough to warrant the use of asymptotic analysis, and has unreliable connections, reflecting the inherent unreliable characteristics of wireless communications? The quality of connectivity measures how easily and reliably a packet sent by a node can reach another node. It complements the use of \\emph{capacity} to measure the quality of a network in saturated traffic scenarios and provides a native measure of the quality of (end-to-end) network connections. In this paper, we explore the use of probabilistic connectivity matrix as a possible tool to measure the quality of network connectivity. Some interesting properties of the probabilistic connectivity matrix and their connections to the quality of connectivity are demonstrated. We argue that the la...

  12. Realistic costs of carbon capture

    Energy Technology Data Exchange (ETDEWEB)

    Al Juaied, Mohammed (Harvard Univ., Cambridge, MA (US). Belfer Center for Science and International Affiaris); Whitmore, Adam (Hydrogen Energy International Ltd., Weybridge (GB))

    2009-07-01

    There is a growing interest in carbon capture and storage (CCS) as a means of reducing carbon dioxide (CO2) emissions. However there are substantial uncertainties about the costs of CCS. Costs for pre-combustion capture with compression (i.e. excluding costs of transport and storage and any revenue from EOR associated with storage) are examined in this discussion paper for First-of-a-Kind (FOAK) plant and for more mature technologies, or Nth-of-a-Kind plant (NOAK). For FOAK plant using solid fuels the levelised cost of electricity on a 2008 basis is approximately 10 cents/kWh higher with capture than for conventional plants (with a range of 8-12 cents/kWh). Costs of abatement are found typically to be approximately US$150/tCO2 avoided (with a range of US$120-180/tCO2 avoided). For NOAK plants the additional cost of electricity with capture is approximately 2-5 cents/kWh, with costs of the range of US$35-70/tCO2 avoided. Costs of abatement with carbon capture for other fuels and technologies are also estimated for NOAK plants. The costs of abatement are calculated with reference to conventional SCPC plant for both emissions and costs of electricity. Estimates for both FOAK and NOAK are mainly based on cost data from 2008, which was at the end of a period of sustained escalation in the costs of power generation plant and other large capital projects. There are now indications of costs falling from these levels. This may reduce the costs of abatement and costs presented here may be 'peak of the market' estimates. If general cost levels return, for example, to those prevailing in 2005 to 2006 (by which time significant cost escalation had already occurred from previous levels), then costs of capture and compression for FOAK plants are expected to be US$110/tCO2 avoided (with a range of US$90-135/tCO2 avoided). For NOAK plants costs are expected to be US$25-50/tCO2. Based on these considerations a likely representative range of costs of abatement from CCS

  13. Historic and pre-historic tsunamis in the Mediterranean and its connected seas: a review on documentation, geological signatures, generation mechanisms and coastal impacts

    Science.gov (United States)

    Papadopoulos, Gerassimos; Gràcia, Eulàlia; Urgeles, Roger; Sallares, Valenti; De Martini, Paolo Marco; Pantosti, Daniela; González, Mauricio; Yalciner, Ahmet C.; Mascle, Jean; Sakellariou, Dimitris; Salamon, Amos; Tinti, Stefano; Fokaefs, Anna; Camerlenghi, Angelo; Novikova, Tatyana; Papageorgiou, Antonia

    2013-04-01

    The origin of tsunamis in the Mediterranean region and its connected seas is reviewed. A variety of historical documentary sources combined with evidence from on-shore and off-shore geological signatures, geomorphological imprints, observations from selected coastal archaeological sites, as well as from instrumental records, clearly indicate that seismic and non-seismic (e.g. volcanism, landslides) tsunami sources can be found in all the seas of the region. Local, regional and basin-wide tsunamis have been documented. An improved map of 22 tsunamigenic zones and their relative potential for tsunami generation is presented. From west to east, the most tsunamigenic zones are situated offshore SW Iberia, in North Algeria, in the Tyrrhenian Calabria and Messina Straits, in the western and eastern segments of the Hellenic Arc, in Corinth Gulf (Central Greece), in the Levantine Sea off-shore the Dead Sea Transform Fault and in the eastern Marmara Sea. The mean recurrence of large (intensity≥8) tsunamis in the entire region is ~90 yrs and in the Mediterranean basin ~102 yrs. However, for most of the historical events it is still doubtful which one was the causative seismic fault and if the tsunami was caused by co-seismic fault dislocation or by earthquake-triggered submarine landslides or by a combined source mechanism (e.g. Lisbon 1755). Instrumentally recorded seismic tsunamis (e.g. Messina 1908, S. Aegean 1956) are still with debatable sources. Calculation of seismic slip slowness factor does not indicate that the 1908 and 1956 events were "tsunami earthquakes". In pre-historical times large tsunamis were caused by volcanic processes in Thera and Etna. A tsunami was supposedly generated in the Holocene by the so-called BIG'95 large submarine landslide in W. Mediterranean. The AD 1650 eruption of the submarine Columbo volcano, off-shore Thera, caused an important tsunami but very little is known about its source mechanism. We concluded that investigating further the

  14. Connecting Grammaticalisation

    DEFF Research Database (Denmark)

    Nørgård-Sørensen, Jens; Heltoft, Lars; Schøsler, Lene

    morphological, topological and constructional paradigms often connect to form complex paradigms. The book introduces the concept of connecting grammaticalisation to describe the formation, restructuring and dismantling of such complex paradigms. Drawing primarily on data from Germanic, Romance and Slavic...

  15. Realistic roofs over a rectilinear polygon

    KAUST Repository

    Ahn, Heekap

    2013-11-01

    Given a simple rectilinear polygon P in the xy-plane, a roof over P is a terrain over P whose faces are supported by planes through edges of P that make a dihedral angle π/4 with the xy-plane. According to this definition, some roofs may have faces isolated from the boundary of P or even local minima, which are undesirable for several practical reasons. In this paper, we introduce realistic roofs by imposing a few additional constraints. We investigate the geometric and combinatorial properties of realistic roofs and show that the straight skeleton induces a realistic roof with maximum height and volume. We also show that the maximum possible number of distinct realistic roofs over P is ((n-4)(n-4)/4 /2⌋) when P has n vertices. We present an algorithm that enumerates a combinatorial representation of each such roof in O(1) time per roof without repetition, after O(n4) preprocessing time. We also present an O(n5)-time algorithm for computing a realistic roof with minimum height or volume. © 2013 Elsevier B.V.

  16. Development of a realistic human airway model.

    Science.gov (United States)

    Lizal, Frantisek; Elcner, Jakub; Hopke, Philip K; Jedelsky, Jan; Jicha, Miroslav

    2012-03-01

    Numerous models of human lungs with various levels of idealization have been reported in the literature; consequently, results acquired using these models are difficult to compare to in vivo measurements. We have developed a set of model components based on realistic geometries, which permits the analysis of the effects of subsequent model simplification. A realistic digital upper airway geometry except for the lack of an oral cavity has been created which proved suitable both for computational fluid dynamics (CFD) simulations and for the fabrication of physical models. Subsequently, an oral cavity was added to the tracheobronchial geometry. The airway geometry including the oral cavity was adjusted to enable fabrication of a semi-realistic model. Five physical models were created based on these three digital geometries. Two optically transparent models, one with and one without the oral cavity, were constructed for flow velocity measurements, two realistic segmented models, one with and one without the oral cavity, were constructed for particle deposition measurements, and a semi-realistic model with glass cylindrical airways was developed for optical measurements of flow velocity and in situ particle size measurements. One-dimensional phase doppler anemometry measurements were made and compared to the CFD calculations for this model and good agreement was obtained.

  17. 弱诱导和可拓扑生成的L-双拓扑空间中的WP-δ连通性%WP -δ connectivity of weakly induced and topologically generated L -bi topological space

    Institute of Scientific and Technical Information of China (English)

    王小霞; 姜金平

    2012-01-01

    WP -δ connectivity of weakly induced and lopologically generated L - bi topological space were studied, that is, if the base space of weakly induced L - bi topological space was WP - δ connected, then weakly induced I - bi topological space was WP -δconnected. If the general bi - topological space was WP -S connected, then its topologically generated L - bi topological space was WP -δ connected.%研究了弱诱导和可拓扑生成的L-双拓扑空间中的WP-δ连通性,并证明了若弱诱导的L -双拓扑空间的底空间是WP-δ连通的,则弱诱导的L-双拓扑空间也是WP-δ连通的;若分明双拓扑空间是WP-δ连通的,则由其拓扑生成的F双拓扑空间是WP-δ连通的.

  18. Role of dissipation in realistic Majorana nanowires

    Science.gov (United States)

    Liu, Chun-Xiao; Sau, Jay D.; Das Sarma, S.

    2017-02-01

    We carry out a realistic simulation of Majorana nanowires in order to understand the latest high-quality experimental data [H. Zhang et al., arXiv:1603.04069 (2016)] and, in the process, develop a comprehensive picture for what physical mechanisms may be operational in realistic nanowires leading to discrepancies between minimal theory and experimental observations (e.g., weakness and broadening of the zero-bias peak and breaking of particle-hole symmetry). Our focus is on understanding specific intriguing features in the data, and our goal is to establish matters of principle controlling the physics of the best possible nanowires available in current experiments. We identify dissipation, finite temperature, multi-sub-band effects, and the finite tunnel barrier as the four most important physical mechanisms controlling the zero-bias conductance peak. Our theoretical results including these realistic effects agree well with the best available experimental data in ballistic nanowires.

  19. Neo-realistic Features in Snow Child

    Institute of Scientific and Technical Information of China (English)

    夏静林

    2013-01-01

    This essay illustrates neo-realistic features in Snow Child. This short story inherits and develops“the typical character in the typical environment”and the traditional linear time order in realistic works. At the same time, it has some changes and transcendent. It uses real brands, events and goods in reality to create a-true to-life picture of the contemporary world. It ex⁃plores deeper in character’s psychology and creates a circular narration with three flashbacks.

  20. Research of Alternating Bus Protection of Grid-connected Photovoltaic Power Generation System%光伏发电系统并网的母线保护研究

    Institute of Scientific and Technical Information of China (English)

    詹红霞; 王秋红; 彭勇

    2012-01-01

    针对光伏发电系统并网技术的特点,分析了系统并网后对配电网继电保护的影响,提出了通过利用母线保护物理对象的函数关系来构建光伏发电系统并网的交流母线保护的ANN模型的新方法。采用该方法解决了光伏发电系统并网造成交流母线保护误动作的问题。%Based on the characteristics of grid-connected technology of photovoltaic power generation system,the effect of grid-connected on relay protection of distribution network is analyzed.A new method for constructing ANN model of alternating bus protection of grid-connected photovoltaic power generation system by using function relationship of physical object is proposed.The malfunction problem of alternating bus protection of grid-connected photovoltaic power generation system can be resolved by the proposed method.

  1. Keeping It Real: How Realistic Does Realistic Fiction for Children Need to Be?

    Science.gov (United States)

    O'Connor, Barbara

    2010-01-01

    O'Connor, an author of realistic fiction for children, shares her attempts to strike a balance between carefree, uncensored, authentic, realistic writing and age-appropriate writing. Of course, complicating that balancing act is the fact that what seems age-appropriate to her might not seem so to everyone. O'Connor suggests that while it may be…

  2. Keeping It Real: How Realistic Does Realistic Fiction for Children Need to Be?

    Science.gov (United States)

    O'Connor, Barbara

    2010-01-01

    O'Connor, an author of realistic fiction for children, shares her attempts to strike a balance between carefree, uncensored, authentic, realistic writing and age-appropriate writing. Of course, complicating that balancing act is the fact that what seems age-appropriate to her might not seem so to everyone. O'Connor suggests that while it may be…

  3. The international regulations for connection of park generators to the grid; As normas internacionais para conexao de parques geradores a rede eletrica

    Energy Technology Data Exchange (ETDEWEB)

    Sangroniz, Natalia; Mora, Jose Arturo; Teixeira [Arteche (Brazil)

    2010-08-15

    This paper gives a general view of the the international regulations for connections of the aeolian parks to the power systems. The requisites countries are compared for frequency control, voltage control, frequency range and sustain capacity.

  4. Blend Shape Interpolation and FACS for Realistic Avatar

    Science.gov (United States)

    Alkawaz, Mohammed Hazim; Mohamad, Dzulkifli; Basori, Ahmad Hoirul; Saba, Tanzila

    2015-03-01

    The quest of developing realistic facial animation is ever-growing. The emergence of sophisticated algorithms, new graphical user interfaces, laser scans and advanced 3D tools imparted further impetus towards the rapid advancement of complex virtual human facial model. Face-to-face communication being the most natural way of human interaction, the facial animation systems became more attractive in the information technology era for sundry applications. The production of computer-animated movies using synthetic actors are still challenging issues. Proposed facial expression carries the signature of happiness, sadness, angry or cheerful, etc. The mood of a particular person in the midst of a large group can immediately be identified via very subtle changes in facial expressions. Facial expressions being very complex as well as important nonverbal communication channel are tricky to synthesize realistically using computer graphics. Computer synthesis of practical facial expressions must deal with the geometric representation of the human face and the control of the facial animation. We developed a new approach by integrating blend shape interpolation (BSI) and facial action coding system (FACS) to create a realistic and expressive computer facial animation design. The BSI is used to generate the natural face while the FACS is employed to reflect the exact facial muscle movements for four basic natural emotional expressions such as angry, happy, sad and fear with high fidelity. The results in perceiving the realistic facial expression for virtual human emotions based on facial skin color and texture may contribute towards the development of virtual reality and game environment of computer aided graphics animation systems.

  5. A Look at Young Children's Realistic Fiction.

    Science.gov (United States)

    Madsen, Jane M.; Wickersham, Elaine B.

    1980-01-01

    Analyzes recent realistic fiction for children produced in the United States in terms of ethnicity, stereotyped behavior, and themes. Concludes that the sample did not reflect equivalent treatment of males and females nor the culturally pluralistic makeup of U.S. society. Provides an annotated bibliography of the books analyzed. (Author/FL)

  6. The romantic paradigm of realist Dostoyevsky

    OpenAIRE

    LIPICH V.V.; LIPICH T.I.

    2015-01-01

    The article is devoted to the inheritance of the traditions of romanticism in the creative activity of young F. M. Dostoyevsky. The article dwells upon the certain points of integration and the typological interrelation of the artistic views of F. M. Dostoyevsky a writer-realist with the esthetic system and poetics of romanticism.

  7. Satellite Maps Deliver More Realistic Gaming

    Science.gov (United States)

    2013-01-01

    When Redwood City, California-based Electronic Arts (EA) decided to make SSX, its latest snowboarding video game, it faced challenges in creating realistic-looking mountains. The solution was NASA's ASTER Global Digital Elevation Map, made available by the Jet Propulsion Laboratory, which EA used to create 28 real-life mountains from 9 different ranges for its award-winning game.

  8. A Look at Young Children's Realistic Fiction.

    Science.gov (United States)

    Madsen, Jane M.; Wickersham, Elaine B.

    1980-01-01

    Analyzes recent realistic fiction for children produced in the United States in terms of ethnicity, stereotyped behavior, and themes. Concludes that the sample did not reflect equivalent treatment of males and females nor the culturally pluralistic makeup of U.S. society. Provides an annotated bibliography of the books analyzed. (Author/FL)

  9. Improving Intuition Skills with Realistic Mathematics Education

    Science.gov (United States)

    Hirza, Bonita; Kusumah, Yaya S.; Darhim; Zulkardi

    2014-01-01

    The intention of the present study was to see the improvement of students' intuitive skills. This improvement was seen by comparing the Realistic Mathematics Education (RME)-based instruction with the conventional mathematics instruction. The subject of this study was 164 fifth graders of elementary school in Palembang. The design of this study…

  10. Culture from the Perspective of Realistic Philosophy

    Directory of Open Access Journals (Sweden)

    Wojciech Daszkiewicz

    2015-12-01

    Full Text Available The article underlines the moments that define the metaphysical understanding of culture. According to this conception, culture in its most basic meaning is rationalization (intellectualization of nature. The article is focused on the following areas: genetic-exemplarist analysis of cultural works and definition of culture from the perspective of realistic philosophy.

  11. Power Quality Improvement Using Custom Power Devices in Squirrel Cage Induction Generator Wind Farm to Weak-Grid Connection by using neuro-fuzzy control

    Directory of Open Access Journals (Sweden)

    Kopella Sai Teja

    2015-02-01

    Full Text Available Wind farm is connected to the grid directly.The wind is not constant voltage fluctuations occur at point of common coupling (PCC and WF terminal . To over come this problem a new compensation strategy is used . By using Custom power devices (UPQC.It injects reactive power at PCC . The advantages of UPQC is it consists of both DVR and D-STATCOM . DVR is connected in series to the line and it injects in phase voltage into the line .D-STATCOM is connected shunt to the line .The internal control strategy is based on management of active and reactive power in series and shunt converters of UPQC . The power exchainge is done by using DC-link

  12. Study on SPLL of Grid-connected PV Generation System%光伏并网发电系统软件锁相技术的研究

    Institute of Scientific and Technical Information of China (English)

    李文杰; 孙志毅; 何秋生

    2012-01-01

    光伏并网发电系统是利用太阳能的主要技术之一,并网逆变器是实现其与电网连接的核心部分.为使光伏并网逆变器逆变输出电流能够更好地跟踪电网电压基波,完成同步锁相功能,本文以1kW单相光伏并网逆变器为研究平台,阐述光伏并网逆变器的工作原理和系统结构,分析并网逆变器的并网控制技术,提出一种基于坐标变换的双park鉴相器的软件锁相技术,最后通过Matlab仿真验证该方法的可行性.%Grid-connected PV system is one of the technologies to use the solar energy. Grid-connected inverter is a core part of linking the grid. In order to make the output current of grid-connected inverter track the grid voltage fundamental and complete the Genlock, this paper uses 1 Kw single-phase photovoltaic grid-connected inverter as research platform. The paper describes the working principle of the photovoltaic grid-connected inverter and the system architecture. It analyzes the control technology of grid-connected inverter and proposes a software phase-locked loop of a dual-park phase detector based on coordinate transformation. At last it verifies the feasibility of this method by Matlab simulation.

  13. Realistic Modeling of Wireless Network Environments

    Science.gov (United States)

    2015-03-01

    1 2.0 INTRODUCTION ... SCM ) .................................................................................................. 8 3.3.3 RF Front Ends...3 Figure 2: SCM -based Emulator (top) Connecting Two Nodes (bottom

  14. Economic evaluation of photovoltaic electric power generation connected to the grid in deregulated electric power markets; Avaliacao economica da geracao de energia eletrica fotovoltaica conectada a rede em mercados eletricos desregulados

    Energy Technology Data Exchange (ETDEWEB)

    Zumaran, David Richard Orosco

    2000-12-01

    This work presents an analysis of economic, tariff and regulating issues related to the introduction of Grid Connected Photovoltaic Systems in a deregulated electric market context; a case study for the peruvian electric market is realized. Based on the pricing system of the electric market, it is developed an economic assessment model that can be used by institutions interested in promoting this technology for generating electricity. (author)

  15. Spectral tunability of realistic plasmonic nanoantennas

    Energy Technology Data Exchange (ETDEWEB)

    Portela, Alejandro; Matsui, Hiroaki; Tabata, Hitoshi, E-mail: tabata@bioeng.t.u-tokyo.ac.jp [Department of Bioengineering, School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656 (Japan); Yano, Takaaki; Hayashi, Tomohiro; Hara, Masahiko [Department of Electronic Chemistry, Tokyo Institute of Technology, Midori-ku, Yokohama, Kanagawa 226-8502 (Japan); Santschi, Christian; Martin, Olivier J. F. [Nanophotonics and Metrology Laboratory, Swiss Federal Institute of Technology Lausanne, Lausanne CH-1015 (Switzerland)

    2014-09-01

    Single nanoantenna spectroscopy was carried out on realistic dipole nanoantennas with various arm lengths and gap sizes fabricated by electron-beam lithography. A significant difference in resonance wavelength between realistic and ideal nanoantennas was found by comparing their spectral response. Consequently, the spectral tunability (96 nm) of the structures was significantly lower than that of simulated ideal nanoantennas. These observations, attributed to the nanofabrication process, are related to imperfections in the geometry, added metal adhesion layer, and shape modifications, which are analyzed in this work. Our results provide important information for the design of dipole nanoantennas clarifying the role of the structural modifications on the resonance spectra, as supported by calculations.

  16. Presupernova neutrinos: realistic emissivities from stellar evolution

    CERN Document Server

    Patton, Kelly M

    2015-01-01

    We present a new calculation of neutrino emissivities and energy spectra from a presupernova, a massive star going through the advanced stages of nuclear burning in the months before becoming a supernova. The contributions from beta decay and electron capture, pair annihilation, plasmon decay, and the photoneutrino process are modeled in detail, using updated tabulated nuclear rates. We also use realistic conditions of temperature, density, electron fraction and nuclear isotopic composition of the star from the state of the art stellar evolution code MESA. It is found that beta processes contribute substantially to the neutrino flux above realistic detection thresholds of few MeV, at selected positions and times in the evolution of the star.

  17. Realistic molecular model of kerogen's nanostructure

    Science.gov (United States)

    Bousige, Colin; Ghimbeu, Camélia Matei; Vix-Guterl, Cathie; Pomerantz, Andrew E.; Suleimenova, Assiya; Vaughan, Gavin; Garbarino, Gaston; Feygenson, Mikhail; Wildgruber, Christoph; Ulm, Franz-Josef; Pellenq, Roland J.-M.; Coasne, Benoit

    2016-05-01

    Despite kerogen's importance as the organic backbone for hydrocarbon production from source rocks such as gas shale, the interplay between kerogen's chemistry, morphology and mechanics remains unexplored. As the environmental impact of shale gas rises, identifying functional relations between its geochemical, transport, elastic and fracture properties from realistic molecular models of kerogens becomes all the more important. Here, by using a hybrid experimental-simulation method, we propose a panel of realistic molecular models of mature and immature kerogens that provide a detailed picture of kerogen's nanostructure without considering the presence of clays and other minerals in shales. We probe the models' strengths and limitations, and show that they predict essential features amenable to experimental validation, including pore distribution, vibrational density of states and stiffness. We also show that kerogen's maturation, which manifests itself as an increase in the sp2/sp3 hybridization ratio, entails a crossover from plastic-to-brittle rupture mechanisms.

  18. Realistic molecular model of kerogen's nanostructure.

    Science.gov (United States)

    Bousige, Colin; Ghimbeu, Camélia Matei; Vix-Guterl, Cathie; Pomerantz, Andrew E; Suleimenova, Assiya; Vaughan, Gavin; Garbarino, Gaston; Feygenson, Mikhail; Wildgruber, Christoph; Ulm, Franz-Josef; Pellenq, Roland J-M; Coasne, Benoit

    2016-05-01

    Despite kerogen's importance as the organic backbone for hydrocarbon production from source rocks such as gas shale, the interplay between kerogen's chemistry, morphology and mechanics remains unexplored. As the environmental impact of shale gas rises, identifying functional relations between its geochemical, transport, elastic and fracture properties from realistic molecular models of kerogens becomes all the more important. Here, by using a hybrid experimental-simulation method, we propose a panel of realistic molecular models of mature and immature kerogens that provide a detailed picture of kerogen's nanostructure without considering the presence of clays and other minerals in shales. We probe the models' strengths and limitations, and show that they predict essential features amenable to experimental validation, including pore distribution, vibrational density of states and stiffness. We also show that kerogen's maturation, which manifests itself as an increase in the sp(2)/sp(3) hybridization ratio, entails a crossover from plastic-to-brittle rupture mechanisms.

  19. Realistic level density calculation for heavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Cerf, N. [Institut de Physique Nucleaire, Orsay (France); Pichon, B. [Observatoire de Paris, Meudon (France); Rayet, M.; Arnould, M. [Institut d`Astronomie et d`Astrophysique, Bruxelles (Belgium)

    1994-12-31

    A microscopic calculation of the level density is performed, based on a combinatorial evaluation using a realistic single-particle level scheme. This calculation relies on a fast Monte Carlo algorithm, allowing to consider heavy nuclei (i.e., large shell model spaces) which could not be treated previously in combinatorial approaches. An exhaustive comparison of the predicted neutron s-wave resonance spacings with experimental data for a wide range of nuclei is presented.

  20. Humanoid robot simulator: a realistic dynamics approach

    OpenAIRE

    Lima, José; Gonçalves, José; Costa, Paulo; Moreira, António

    2008-01-01

    This paper describes a humanoid robot simulator with realistic dynamics. As simulation is a powerful tool for speeding up the control software development, the suggested accurate simulator allows to accomplish this goal. The simulator, based on the Open Dynamics Engine and GLScene graphics library, provides instant visual feedback and allows the user to test any control strategy without damaging the real robot in the early stages of the development. The proposed simulator also captures some c...

  1. Realistic Behaviour Simulation of a Humanoid Robot

    OpenAIRE

    2008-01-01

    This paper describes a humanoid robot simulator with realistic dynamics. As simulation is a powerful tool for speeding up the control software development, the proposed accurate simulator allows to fulfil this goal. The simulator is based on the Open Dynamics Engine and GLScene graphics library, providing instant visual feedback. User is able to test any control strategy without bringing damage to the real robot in the early stages of the development. The proposed simulator also captures some...

  2. Algorithm for Realistic Modeling of Graphitic Systems

    Directory of Open Access Journals (Sweden)

    A.V. Khomenko

    2011-01-01

    Full Text Available An algorithm for molecular dynamics simulations of graphitic systems using realistic semiempirical interaction potentials of carbon atoms taking into account both short-range and long-range contributions is proposed. Results of the use of the algorithm for a graphite sample are presented. The scalability of the algorithm depending on the system size and the number of processor cores involved in the calculations is analyzed.

  3. Dynamical Symmetries Reflected in Realistic Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Sviratcheva, K.D.; Draayer, J.P.; /Louisiana State U.; Vary, J.P.; /Iowa State U. /LLNL, Livermore /SLAC

    2007-04-06

    Realistic nucleon-nucleon (NN) interactions, derived within the framework of meson theory or more recently in terms of chiral effective field theory, yield new possibilities for achieving a unified microscopic description of atomic nuclei. Based on spectral distribution methods, a comparison of these interactions to a most general Sp(4) dynamically symmetric interaction, which previously we found to reproduce well that part of the interaction that is responsible for shaping pairing-governed isobaric analog 0{sup +} states, can determine the extent to which this significantly simpler model Hamiltonian can be used to obtain an approximate, yet very good description of low-lying nuclear structure. And furthermore, one can apply this model in situations that would otherwise be prohibitive because of the size of the model space. In addition, we introduce a Sp(4) symmetry breaking term by including the quadrupole-quadrupole interaction in the analysis and examining the capacity of this extended model interaction to imitate realistic interactions. This provides a further step towards gaining a better understanding of the underlying foundation of realistic interactions and their ability to reproduce striking features of nuclei such as strong pairing correlations or collective rotational motion.

  4. Realistically Rendering SoC Traffic Patterns with Interrupt Awareness

    DEFF Research Database (Denmark)

    Angiolini, Frederico; Mahadevan, Sharkar; Madsen, Jan;

    2005-01-01

    traffic generators have been used to overcome such an issue. However, target applications increasingly present non-trivial execution flows and synchronization patterns, especially in presence of underlying operating systems and when exploiting interrupt facilities. This property makes it very difficult...... to generate realistic test traffic. This paper presents a selection of applications using interrupt-based synchronization; a reference methodology to split such applications in execution subflows and to adjust the overall execution stream based upon hardware events; a reactive simulation device capable......In Multi-Processor System-on-Chip (MPSoC) design stages, accurate modeling of IP behaviour is crucial to analyze interconnect effectiveness. However, parallel development of components may cause IP core models to be still unavailable when tuning communication performance. Traditionally, synthetic...

  5. About Connections

    Directory of Open Access Journals (Sweden)

    Kathleen S Rockland

    2015-05-01

    Full Text Available Despite the attention attracted by connectomics, one can lose sight of the very real questions concerning What are connections? In the neuroimaging community, structural connectivity is ground truth and underlying constraint on functional or effective connectivity. It is referenced to underlying anatomy; but, as increasingly remarked, there is a large gap between the wealth of human brain mapping and the relatively scant data on actual anatomical connectivity. Moreover, connections have typically been discussed as pairwise, point x projecting to point y (or: to points y and z, or more recently, in graph theoretical terms, as nodes or regions and the interconnecting edges. This is a convenient shorthand, but tends not to capture the richness and nuance of basic anatomical properties as identified in the classic tradition of tracer studies. The present short review accordingly revisits connectional weights, heterogeneity, reciprocity, topography, and hierarchical organization, drawing on concrete examples. The emphasis is on presynaptic long-distance connections, motivated by the intention to probe current assumptions and promote discussions about further progress and synthesis.

  6. Comprehensive Evaluation Model of Photovoitaic Generation Grid-connected Planning and Its Application%光伏发电并网规划综合评价模型及其应用

    Institute of Scientific and Technical Information of China (English)

    王琬; 曾博; 刘宗歧; 张建华

    2011-01-01

    This paper reveals influence mechanism and operation theory of grid- connected photovoltaic (PV) generation on traditional power grid planning modes, and analyzes the improvement in security, reliability, economics and environmental benefits of power grid with grid - connected PV generation. A series of comprehensive quantitative indices, such as remission degree of power transmission, the improvement rate of system voltage and environment, are proposed to establish a comprehensive evaluation indices system for PV generation grid - connected planning. A new methodology to evaluate the stability degree of solar energy by introducing the concepts of unavailability frequency and average unavailability duration of solar resource is proposed. The weights are determined based on information entropy method, and analytical hierarchy process (AHP) is used to comprehensively evaluate PV generation grid - connected planning. Simulation results show that the proposed evaluation system can reflect the influences of grid - connected PV generation on power grid planning and operation effectively, which provides important reference for the further practices.%在揭示光伏发电并网对传统电网规划模式的影响机制与作用原理的基础上,深入分析光伏电源接入对电网安全性、可靠性、经济性、环境效益的改善效果,提出传输功率缓解度、系统电压改善率、环境改善率等一系列综合性量化指标,构建了一套较完整的光伏发电并网规划综合评价指标体系.提出了光能不可用频率和光能不可用平均持续时间两项新指标以评价光伏系统能量供给的稳定程度.采用基于信息熵修正的权重确定方法,并利用群决策层次分析法实现对光伏发电并网规划的综合评判决策.仿真计算结果表明,本文方法能够全面、有效地反映光伏电源并网后对电网规划运行的影响,可为灵活规划光伏电源位置和容量提供重要的参考依据.

  7. Gendered Connections

    DEFF Research Database (Denmark)

    Jensen, Steffen Bo

    2009-01-01

    This article explores the gendered nature of urban politics in Cape Town by focusing on a group of female, township politicians. Employing the Deleuzian concept of `wild connectivity', it argues that these politically entrepreneurial women were able to negotiate a highly volatile urban landscape...... space also drew on quite traditional notions of female respectability. Furthermore, the article argues, the form of wild connectivity to an extent was a function of the political transition, which destabilized formal structures of gendered authority. It remains a question whether this form...... of connectivity might endure, as Capetonian politics assumes a post-apartheid structure....

  8. Modeling and Coordinated Control of Grid-Connected PV Generation System With Energy Storage Devices%光-储联合并网发电系统建模与协调控制

    Institute of Scientific and Technical Information of China (English)

    孔令国; 蔡国伟; 杨德友; 孙正龙

    2013-01-01

    针对光伏并网发电系统具有随机性,且不具备故障暂态电压支撑能力的特征,提出一种有效调节功率且改善低电压穿越能力的光储联合并网发电系统动态模型及协调控制策略.在电力系统仿真分析平台DIgSILENT/Power Factory中建立了光储联合并网发电系统协调控制及低电压穿越功能模型.应用协调控制策略实现储能系统和静止同步补偿器功率平衡,维持并网点电压稳定.利用气象和负荷数据,验证了上述模型及协调控制策略的有效性.%In allusion to the randomness of grid-connected PV generation system that does not possess the ability to support fault-caused transient voltage, a dynamic model and corresponding coordinated control strategy for grid-connected PV generation system with energy storage devices that can effectively regulate power output and improve low-voltage ride through (LVRT) are proposed. A coordinated control model of grid-connected PV generation system with energy storage devices and an LVRT model are built on power system simulation analysis platform DIgSILENT/Power Factory. Using coordinated control strategy, the power balance between energy storage devices and static synchronous compensator (STATCOM) is implemented to make the voltage at grid-connected point stable. Availability of the proposed model and coordinated control strategy is verified by meteorological data and load data.

  9. ANALYSIS OF PROCESSES IN AN INDEPENDENT GENERATOR WITH A NONCONTACT CASCADE THREE-PHASE MODULATED EXCITER VIA A STAR-CONNECTED CIRCUIT WITH A COMMON MODULATOR PHASE CONNECTION UNDER OPERATION TO AN INDUCTION MOTORS SITE

    Directory of Open Access Journals (Sweden)

    K.M. Vasyliv

    2013-04-01

    Full Text Available By means of a mathematical experiment, electromagnetic and electromechanical processes in an independent electric power supply system based on an asynchronized generator with a three-phase modulated exciter are investigated. The processes are analyzed to specify the working capacity of the power supply system during its operation to an induction motors site. Regularities of the electromagnetic and electromechanical processes behavior versus load intensity and the switch control system parameters are identified.

  10. HR Connect

    Data.gov (United States)

    US Agency for International Development — HR Connect is the USAID HR personnel system which allows HR professionals to process HR actions related to employee's personal and position information. This system...

  11. Adiabatic hyperspherical analysis of realistic nuclear potentials

    CERN Document Server

    Daily, K M; Greene, Chris H

    2015-01-01

    Using the hyperspherical adiabatic method with the realistic nuclear potentials Argonne V14, Argonne V18, and Argonne V18 with the Urbana IX three-body potential, we calculate the adiabatic potentials and the triton bound state energies. We find that a discrete variable representation with the slow variable discretization method along the hyperradial degree of freedom results in energies consistent with the literature. However, using a Laguerre basis results in missing energy, even when extrapolated to an infinite number of basis functions and channels. We do not include the isospin $T=3/2$ contribution in our analysis.

  12. Cellular automaton for realistic modelling of landslides

    CERN Document Server

    Segrè, E; Enrico Segre; Chiara Deangeli

    1994-01-01

    We develop a numerical model for the simulation of debris flow in landslides over a complex three dimensional topography. The model is based on a lattice, in which debris can be transferred among nearest neighbours according to established empirical relationships for granular flows. The model is validated comparing its results with reported field data. Our model is in fact a realistic elaboration of simpler ``sandpile automata'', which have in recent years been studied as supposedly paradigmatic of ``self organized criticality''. Statistics and scaling properties of the simulation are examined, showing that the model has an intermittent behaviour.

  13. Realistic searches on stretched exponential networks

    Indian Academy of Sciences (India)

    Parogama Sen

    2008-08-01

    We consider navigation or search schemes on networks which have a degree distribution of the form () ∝ exp(−). In addition, the linking probability is taken to be dependent on social distances and is governed by a parameter . The searches are realistic in the sense that not all search chains can be completed. An estimate of = ρ/d, where is the success rate and d the dynamic path length, shows that for a network of nodes, ∝ - in general. Dynamic small world effect, i.e., ≃ 0 is shown to exist in a restricted region of the - plane.

  14. An Introduction to a Realistic Quantum Physics

    CERN Document Server

    Preparata, Giuliano

    2003-01-01

    This book is a remarkable synthesis, a clear and simple introduction to Quantum Physics with a sort of Galilean dialogue on the supreme systems of contemporary Physics. The author, whose research interests and work extended from quarks to liquid systems and from crystals to stars, introduces the common conceptual and mathematical framework of all quantum theories, realistic enough to successfully confront Nature: Quantum Field Theory applied to the study of both dilute and condensed matter. In the dilute limit, quantum mechanics is shown to be a good approximation to Quantum Field Theory. Howe

  15. Simulating realistic predator signatures in quantitative fatty acid signature analysis

    Science.gov (United States)

    Bromaghin, Jeffrey F.

    2015-01-01

    Diet estimation is an important field within quantitative ecology, providing critical insights into many aspects of ecology and community dynamics. Quantitative fatty acid signature analysis (QFASA) is a prominent method of diet estimation, particularly for marine mammal and bird species. Investigators using QFASA commonly use computer simulation to evaluate statistical characteristics of diet estimators for the populations they study. Similar computer simulations have been used to explore and compare the performance of different variations of the original QFASA diet estimator. In both cases, computer simulations involve bootstrap sampling prey signature data to construct pseudo-predator signatures with known properties. However, bootstrap sample sizes have been selected arbitrarily and pseudo-predator signatures therefore may not have realistic properties. I develop an algorithm to objectively establish bootstrap sample sizes that generates pseudo-predator signatures with realistic properties, thereby enhancing the utility of computer simulation for assessing QFASA estimator performance. The algorithm also appears to be computationally efficient, resulting in bootstrap sample sizes that are smaller than those commonly used. I illustrate the algorithm with an example using data from Chukchi Sea polar bears (Ursus maritimus) and their marine mammal prey. The concepts underlying the approach may have value in other areas of quantitative ecology in which bootstrap samples are post-processed prior to their use.

  16. Modeling of Transmembrane Potential in Realistic Multicellular Structures before Electroporation.

    Science.gov (United States)

    Murovec, Tomo; Sweeney, Daniel C; Latouche, Eduardo; Davalos, Rafael V; Brosseau, Christian

    2016-11-15

    Many approaches for studying the transmembrane potential (TMP) induced during the treatment of biological cells with pulsed electric fields have been reported. From the simple analytical models to more complex numerical models requiring significant computational resources, a gamut of methods have been used to recapitulate multicellular environments in silico. Cells have been modeled as simple shapes in two dimensions as well as more complex geometries attempting to replicate realistic cell shapes. In this study, we describe a method for extracting realistic cell morphologies from fluorescence microscopy images to generate the piecewise continuous mesh used to develop a finite element model in two dimensions. The preelectroporation TMP induced in tightly packed cells is analyzed for two sets of pulse parameters inspired by clinical irreversible electroporation treatments. We show that high-frequency bipolar pulse trains are better, and more homogeneously raise the TMP of tightly packed cells to a simulated electroporation threshold than conventional irreversible electroporation pulse trains, at the expense of larger applied potentials. Our results demonstrate the viability of our method and emphasize the importance of considering multicellular effects in the numerical models used for studying the response of biological tissues exposed to electric fields. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  17. Towards Modeling Realistic Mobility for Performance Evaluations in MANET

    Science.gov (United States)

    Aravind, Alex; Tahir, Hassan

    Simulation modeling plays crucial role in conducting research on complex dynamic systems like mobile ad hoc networks and often the only way. Simulation has been successfully applied in MANET for more than two decades. In several recent studies, it is observed that the credibility of the simulation results in the field has decreased while the use of simulation has steadily increased. Part of this credibility crisis has been attributed to the simulation of mobility of the nodes in the system. Mobility has such a fundamental influence on the behavior and performance of mobile ad hoc networks. Accurate modeling and knowledge of mobility of the nodes in the system is not only helpful but also essential for the understanding and interpretation of the performance of the system under study. Several ideas, mostly in isolation, have been proposed in the literature to infuse realism in the mobility of nodes. In this paper, we attempt a holistic analysis of creating realistic mobility models and then demonstrate creation and analysis of realistic mobility models using a software tool we have developed. Using our software tool, desired mobility of the nodes in the system can be specified, generated, analyzed, and then the trace can be exported to be used in the performance studies of proposed algorithms or systems.

  18. UAV based distributed ATR under realistic simulated environmental effects

    Science.gov (United States)

    Chen, Xiaohan; Gong, Shanshan; Schmid, Natalia A.; Valenti, Matthew C.

    2007-04-01

    Over the past several years, the military has grown increasingly reliant upon the use of unattended aerial vehicles (UAVs) for surveillance missions. There is an increasing trend towards fielding swarms of UAVs operating as large-scale sensor networks in the air. Such systems tend to be used primarily for the purpose of acquiring sensory data with the goal of automatic detection, identification, and tracking objects of interest. These trends have been paralleled by advances in both distributed detection, image/signal processing and data fusion techniques. Furthermore, swarmed UAV systems must operate under severe constraints on environmental conditions and sensor limitations. In this work, we investigate the effects of environmental conditions on target detection and recognition performance in a UAV network. We assume that each UAV is equipped with an optical camera, and use a realistic computer simulation to generate synthetic images. The detection algorithm relies on Haar-based features while the automatic target recognition (ATR) algorithm relies on Bessel K features. The performance of both algorithms is evaluated using simulated images that closely mimic data acquired in a UAV network under realistic environmental conditions. We design several fusion techniques and analyze both the case of a single observation and the case of multiple observations of the same target.

  19. Shadow obstacle model for realistic corner-turning behavior in crowd simulation

    Institute of Scientific and Technical Information of China (English)

    Gao-qi HE; Yi JIN; Qi CHEN; Zhen LIU; Wen-hui YUE; Xing-jian LU

    2016-01-01

    This paper describes a novel model known as the shadow obstacle model to generate a realistic corner-turning be-havior in crowd simulation. The motivation for this model comes from the observation that people tend to choose a safer route rather than a shorter one when turning a corner. To calculate a safer route, an optimization method is proposed to generate the corner-turning rule that maximizes the viewing range for the agents. By combining psychological and physical forces together, a full crowd simulation framework is established to provide a more realistic crowd simulation. We demonstrate that our model produces a more realistic corner-turning behavior by comparison with real data obtained from the experiments. Finally, we per-form parameter analysis to show the believability of our model through a series of experiments.

  20. Realistic affective forecasting: The role of personality.

    Science.gov (United States)

    Hoerger, Michael; Chapman, Ben; Duberstein, Paul

    2016-11-01

    Affective forecasting often drives decision-making. Although affective forecasting research has often focused on identifying sources of error at the event level, the present investigation draws upon the "realistic paradigm" in seeking to identify factors that similarly influence predicted and actual emotions, explaining their concordance across individuals. We hypothesised that the personality traits neuroticism and extraversion would account for variation in both predicted and actual emotional reactions to a wide array of stimuli and events (football games, an election, Valentine's Day, birthdays, happy/sad film clips, and an intrusive interview). As hypothesised, individuals who were more introverted and neurotic anticipated, correctly, that they would experience relatively more unpleasant emotional reactions, and those who were more extraverted and less neurotic anticipated, correctly, that they would experience relatively more pleasant emotional reactions. Personality explained 30% of the concordance between predicted and actual emotional reactions. Findings suggest three purported personality processes implicated in affective forecasting, highlight the importance of individual-differences research in this domain, and call for more research on realistic affective forecasts.

  1. Realistic Radio Communications in Pilot Simulator Training

    Science.gov (United States)

    Burki-Cohen, Judith; Kendra, Andrew J.; Kanki, Barbara G.; Lee, Alfred T.

    2000-01-01

    Simulators used for total training and evaluation of airline pilots must satisfy stringent criteria in order to assure their adequacy for training and checking maneuvers. Air traffic control and company radio communications simulation, however, may still be left to role-play by the already taxed instructor/evaluators in spite of their central importance in every aspect of the flight environment. The underlying premise of this research is that providing a realistic radio communications environment would increase safety by enhancing pilot training and evaluation. This report summarizes the first-year efforts of assessing the requirement and feasibility of simulating radio communications automatically. A review of the training and crew resource/task management literature showed both practical and theoretical support for the need for realistic radio communications simulation. A survey of 29 instructor/evaluators from 14 airlines revealed that radio communications are mainly role-played by the instructor/evaluators. This increases instructor/evaluators' own workload while unrealistically lowering pilot communications load compared to actual operations, with a concomitant loss in training/evaluation effectiveness. A technology review searching for an automated means of providing radio communications to and from aircraft with minimal human effort showed that while promising, the technology is still immature. Further research and the need for establishing a proof-of-concept are also discussed.

  2. 逆变型分布式电源并网系统的失步保护研究%Out-of-Step Separation Protection of Inverter-Based Grid-Connecting System for Distributed Generation

    Institute of Scientific and Technical Information of China (English)

    赵杰; 张艳霞; 宣文博; 童锐; 田斌

    2013-01-01

    In allusion to the out-of-step fault occurred in inverter-based grid-connecting system for distributed generation, the differences between the out-of-step fault occurred in traditional power grid composed of rotating generators and that occurred in inverter-based grid-connecting system for distributed generation are analyzed, and a new principle for out-of-step separation protection for inverter-based grid-connecting system for distributed generation is proposed. Firstly, the absolute value of apparent impedance angle deviation at the point of common coupling (PCC) is utilized to construct the tripping criterion and out-of-step separation criterion respectively; secondly, the absolute value of variation acceleration of apparent impedance angle is used to judge the out-of-step state. A model of grid-connected three-phase photovoltaic (PV) power system is built by MATLAB/SIMULINK to simulate the three-phase short-circuit fault and out-of-step fault. Simulation results show that the proposed new principle for out-of-step separation protection is correct and the principle is clear, the three-phase short-circuit fault occurred in inverter-based grid-connecting system for distributed generation can be precisely distinguished from the out-of-step fault, and the proposed protection principle is not affected by three-phase short-circuit fault occurred in inverter-based grid-connecting system for distributed generation.%针对逆变型分布式电源并网系统中存在的失步问题,分析了逆变型分布式电源并网系统失步和传统旋转型电源电网失步的区别,提出了适用于分布式电源并网系统的失步保护新原理.该保护首先利用公共耦合节点处视在阻抗角偏移量的绝对值构建失步保护启动判据,其次利用视在阻抗角变化的加速度绝对值来判断失步状态.通过MATLAB/SIMULINK搭建三相光伏并网发电系统模型,进行三相短路和失步仿真.仿真结果验证了提出的失步保护原

  3. Connected Traveler

    Energy Technology Data Exchange (ETDEWEB)

    2016-06-01

    The Connected Traveler framework seeks to boost the energy efficiency of personal travel and the overall transportation system by maximizing the accuracy of predicted traveler behavior in response to real-time feedback and incentives. It is anticipated that this approach will establish a feedback loop that 'learns' traveler preferences and customizes incentives to meet or exceed energy efficiency targets by empowering individual travelers with information needed to make energy-efficient choices and reducing the complexity required to validate transportation system energy savings. This handout provides an overview of NREL's Connected Traveler project, including graphics, milestones, and contact information.

  4. Dynamics of entanglement in realistic chains of superconducting qubits

    CERN Document Server

    Tsomokos, D I; Huelga, S F; Plenio, M B

    2006-01-01

    The quantum dynamics of chains of superconducting qubits is analyzed under realistic experimental conditions. Electromagnetic fluctuations due to the background circuitry, finite temperature in the external environment, and disorder in the initial preparation and the control parameters are taken into account. It is shown that the amount of disorder that is typically present in current experiments does not affect the entanglement dynamics significantly. However, the effect of the environmental noise can modify entanglement generation and propagation across the chain. We study the persistence of coherent effects in the presence of noise and possible ways to efficiently detect the presence of quantum entanglement. We also discuss under which circumstances the system exhibits steady state entanglement for both short (N30) chains and show that there are parameter regimes where the steady state entanglement is strictly non-monotonic as a function of the noise strength. We present optimized schemes for entanglement ...

  5. Unsteady velocity measurements in a realistic intracranial aneurysm model

    Science.gov (United States)

    Ugron, Ádám; Farinas, Marie-Isabelle; Kiss, László; Paál, György

    2012-01-01

    The initiation, growth and rupture of intracranial aneurysms are intensively studied by computational fluid dynamics. To gain confidence in the results of numerical simulations, validation of the results is necessary. To this end the unsteady flow was measured in a silicone phantom of a realistic intracranial aneurysm. A flow circuit was built with a novel unsteady flow rate generating method, used to model the idealised shape of the heartbeat. This allowed the measurement of the complex three-dimensional velocity distribution by means of laser-optical methods such as laser doppler anemometry (LDA) and particle image velocimetry (PIV). The PIV measurements, available with high temporal and spatial distribution, were found to have good agreement with the control LDA measurements. Furthermore, excellent agreement was found with the numerical results.

  6. Towards realistic string vacua from branes at singularities

    CERN Document Server

    Conlon, Joseph P; Quevedo, Fernando

    2009-01-01

    We report on progress towards constructing string models incorporating both realistic D-brane matter content and full moduli stabilisation with dynamical low-scale supersymmetry breaking. The general framework is that of local D-brane models embedded into the LARGE volume approach to moduli stabilisation. We review quiver theories on del Pezzo n (dP_n) singularities including both D3 and D7 branes. We provide supersymmetric examples with three quark/lepton families and the gauge symmetries of the Standard, Left-Right Symmetric, Pati-Salam and Trinification models, without unwanted chiral exotics. We describe how the singularity structure leads to family symmetries governing the Yukawa couplings which can give mass hierarchies among the different generations. We outline how these models can be embedded into compact Calabi-Yau compactifications with LARGE volume moduli stabilisation, and state the minimal conditions for this to be possible. We study the general structure of soft supersymmetry breaking. At the s...

  7. Grid-Connected Fuzzy-PID Control of PV Power Generation System%光伏发电系统的并网模糊PID控制

    Institute of Scientific and Technical Information of China (English)

    贺运胜

    2013-01-01

    在三相两级式并网逆变器数学模型的基础上,将模糊PID控制策略引入光伏发电系统的并网控制中.通过数字仿真和物理仿真表明模糊控制与PID控制相结合的模糊PID控制,改善了光伏系统并网控制的动态过程,能够实现光伏系统的平滑并网.%ied in the grid control of PV system in this paper. The digital simulation and physical simulation show that the fuzzy-PID control strategy can improve the PV system grid control dynamic process and realize the smooth connection of the PV system with the power grid.

  8. Plasticity-modulated seizure dynamics for seizure termination in realistic neuronal models

    NARCIS (Netherlands)

    Koppert, M.M.J.; Kalitzin, S.; Lopes da Silva, F.H.; Viergever, M.A.

    2011-01-01

    In previous studies we showed that autonomous absence seizure generation and termination can be explained by realistic neuronal models eliciting bi-stable dynamics. In these models epileptic seizures are triggered either by external stimuli (reflex epilepsies) or by internal fluctuations. This scena

  9. Plasticity-modulated seizure dynamics for seizure termination in realistic neuronal models

    NARCIS (Netherlands)

    Koppert, M.M.J.; Kalitzin, S.; Lopes da Silva, F.H.; Viergever, M.A.

    2011-01-01

    In previous studies we showed that autonomous absence seizure generation and termination can be explained by realistic neuronal models eliciting bi-stable dynamics. In these models epileptic seizures are triggered either by external stimuli (reflex epilepsies) or by internal fluctuations. This

  10. Order-theoretical connectivity

    Directory of Open Access Journals (Sweden)

    T. A. Richmond

    1990-01-01

    Full Text Available Order-theoretically connected posets are introduced and applied to create the notion of T-connectivity in ordered topological spaces. As special cases T-connectivity contains classical connectivity, order-connectivity, and link-connectivity.

  11. Getting Connected

    Science.gov (United States)

    Larkin, Patrick

    2011-01-01

    That the world outside schools is changing faster than ever is old news. Unfortunately, that the world "inside" schools is changing at a glacial pace is even older news. As school leaders, principals have an important choice to make as they move into the second decade of the 21st century. School leaders have a moral obligation to connect and…

  12. Connecting dots

    DEFF Research Database (Denmark)

    Murakami, Kyoko; Jacobs, Rachel L.

    2017-01-01

    of connecting the dots of recalled moments of individual family members lives and is geared towards building a family’s shared future for posterity. Lastly, we consider a wider implication of family reminiscence in terms of human development. http://www.infoagepub.com/products/Memory-Practices-and-Learning...

  13. Learning Connections

    Science.gov (United States)

    Royer, Regina D.; Richards, Patricia O.

    2005-01-01

    In this edition of Learning Connections, the authors show how technology can enhance study of weather patterns, reading comprehension, real-world training, critical thinking, health education, and art criticism. The following sections are included: (1) Social Studies; (2) Language Arts; (3) Computer Science and ICT; (4) Art; and (5) Health.…

  14. Best connected rectangular arrangements

    Directory of Open Access Journals (Sweden)

    Krishnendra Shekhawat

    2016-03-01

    Full Text Available It can be found quite often in the literature that many well-known architects have employed either the golden rectangle or the Fibonacci rectangle in their works. On contrary, it is rare to find any specific reason for using them so often. Recently, Shekhawat (2015 proved that the golden rectangle and the Fibonacci rectangle are one of the best connected rectangular arrangements and this may be one of the reasons for their high presence in architectural designs. In this work we present an algorithm that generates n-4 best connected rectangular arrangements so that the proposed solutions can be further used by architects for their designs.

  15. Teaching Practice in a Realistic Context

    Institute of Scientific and Technical Information of China (English)

    1994-01-01

    Introduction For two academic years, Teaching Practice (TP), an important component of the in-service Advanced Teacher Training Course at Chongqing University, was set up in an almost ideal context: students specially recruited, materials selected by the trainees and photo-copying facilities provided. While trainees felt very excited by their performances during TP, when all the excitement had gone, they felt less optimistic at the thought of the constraints which would be placed on their teaching in their own institutions. So their evaluation of TP ended with a "Yes, but" statement. Drawing on insights gained from those two years, the British lecturers and Chinese counterparts generally felt that TP should, in future, operate within a realistic context. In this paper, we shall report how TP was conducted within our Foreign Languages Department.

  16. Realistic Detectability of Close Interstellar Comets

    CERN Document Server

    Cook, Nathaniel V; Granvik, Mikael; Stephens, Denise C

    2016-01-01

    During the planet formation process, billions of comets are created and ejected into interstellar space. The detection and characterization of such interstellar comets (also known as extra-solar planetesimals or extra-solar comets) would give us in situ information about the efficiency and properties of planet formation throughout the galaxy. However, no interstellar comets have ever been detected, despite the fact that their hyperbolic orbits would make them readily identifiable as unrelated to the solar system. Moro-Mart\\'in et al. 2009 have made a detailed and reasonable estimate of the properties of the interstellar comet population. We extend their estimates of detectability with a numerical model that allows us to consider "close" interstellar comets, e.g., those that come within the orbit of Jupiter. We include several constraints on a "detectable" object that allow for realistic estimates of the frequency of detections expected from the Large Synoptic Survey Telescope (LSST) and other surveys. The inf...

  17. Realistic page-turning of electronic books

    Science.gov (United States)

    Fan, Chaoran; Li, Haisheng; Bai, Yannan

    2014-01-01

    The booming electronic books (e-books), as an extension to the paper book, are popular with readers. Recently, many efforts are put into the realistic page-turning simulation o f e-book to improve its reading experience. This paper presents a new 3D page-turning simulation approach, which employs piecewise time-dependent cylindrical surfaces to describe the turning page and constructs smooth transition method between time-dependent cylinders. The page-turning animation is produced by sequentially mapping the turning page into the cylinders with different radii and positions. Compared to the previous approaches, our method is able to imitate various effects efficiently and obtains more natural animation of turning page.

  18. Realistic Multimedia Simulations for Informatics Students

    Directory of Open Access Journals (Sweden)

    Ioannis Pachoulaki

    2012-08-01

    Full Text Available Realistic multimedia simulations are effective in helping students overcome their fear of physics and gain fundamental knowledge of physical processes. An elective course has been designed in the Applied Informatics and Multimedia Department at TEI of Crete to help informatics students overcome their physics shyness by hands-on experience on scientific multimedia simulations. The approach is justified in terms of the rich employment opportunities in the game and multimedia industries where a sound basis in physics, mathematics and numerical analysis is a necessity. Student feedback shows that they embrace the adopted approach, which uses open source tools to minimize programming so as to allow both instructor and students to focus on the science and complete a greater number of simulations.

  19. Realistic model for radiation-matter interaction

    CERN Document Server

    Pakula, R A

    2004-01-01

    This paper presents a realistic model that describes radiation-matter interactions. This is achieved by a generalization of first quantization, where the Maxwell equations are interpreted as the electromagnetic component of the Schrodinger equation. This picture is complemented by the consideration of electrons and photons as real particles in three-dimensional space, following guiding conditions derived from the particle-wave-functions to which they are associated. The guiding condition for the electron is taken from Bohmian mechanics, while the photon velocity is defined as the ratio between the Poynting vector and the electromagnetic energy density. The case of many particles is considered, taking into account their statistical properties. The formalism is applied to a two level system, providing an intuitive description for spontaneous emission, Lamb shift, scattering, absorption, dispersion, resonance fluorescence and vacuum fields. This model describes quantum jumps by the entanglement between the photo...

  20. Performance Evaluation of MANET in Realistic Environment

    Directory of Open Access Journals (Sweden)

    Shailender Gupta

    2012-07-01

    Full Text Available In order to facilitate communication in Mobile Ad hoc Network (MANET, routing protocols are developed. The performance of these protocols depends upon various factors such as: transmission range, number of nodes deployed and mobility of the nodes. Another factor which affects the performance of MANET routing protocols is the environment in which ad hoc network is deployed. The MANET environment may contain obstacles such as mountains lakes, buildings and river. These obstacles restrict nodes movement but may or may not obstruct the effective transmission range of nodes deployed. This paper is an effort to evaluate the performance of MANET routing protocols in presence of obstacles by designing a simulator in MATLAB-10. To make the situation more realistic obstacle of different shapes, size, number and type were introduced in the simulation region. We found significant impact of the same on the performance of routing protocols

  1. E. H. Carr: En kompleks realist

    DEFF Research Database (Denmark)

    Meyn, Carina Ann

    2008-01-01

    Edward Hallett Carr er blevet kaldt alt fra realist til utopist til slet og ret ,,farlig". Denne artikel giver en bedre forstaelse af, hvorfor et centralt pejlemærke i disci­plinen international politik bliver beskrevet på så mange - tilsyneladende - modsætningsfyldte måder. I stedet for at tage...... udgangspunkt i en realistisk eller en utopisk læsning af Carrs værker bidrager denne artikel med en tredje læsning af Carrs teori, der samtænker ,,den realistiske Carr" og ,,den utopiske Carr". Det overordnede argument i artiklen er, at for at kunne finde mening og sammen­hæng i Carrs politiske teori, ma man...... nødvendigvis samtænke Carrs realisme og utopisme med hans underliggende radikalisme....

  2. The Radiative Tail of Realistic Gravitational Collapse

    CERN Document Server

    Hod, S

    2000-01-01

    An astrophysically realistic model of wave dynamics in black-hole spacetimes must involve a {\\it non}-spherical background geometry with {\\it angular momentum}. We consider the evolution of {\\it gravitational} (and electromagnetic) perturbations in {\\it rotating} Kerr spacetimes. We show that a rotating Kerr black hole becomes ``bald'' {\\it slower} than the corresponding spherically-symmetric Schwarzschild black hole. Moreover, our results {\\it turn over} the traditional belief (which has been widely accepted during the last three decades) that the late-time tail of gravitational collapse is universal. In particular, we show that different fields have {\\it different} decaying rates. Our results are also of importance both to the study of the no-hair conjecture and the mass-inflation scenario (stability of Cauchy horizons).

  3. Helioseismology of a Realistic Magnetoconvective Sunspot Simulation

    Science.gov (United States)

    Braun, D. C.; Birch, A. C.; Rempel, M.; Duvall, T. L., Jr.

    2012-01-01

    We compare helioseismic travel-time shifts measured from a realistic magnetoconvective sunspot simulation using both helioseismic holography and time-distance helioseismology, and measured from real sunspots observed with the Helioseismic and Magnetic Imager instrument on board the Solar Dynamics Observatory and the Michelson Doppler Imager instrument on board the Solar and Heliospheric Observatory. We find remarkable similarities in the travel-time shifts measured between the methodologies applied and between the simulated and real sunspots. Forward modeling of the travel-time shifts using either Born or ray approximation kernels and the sound-speed perturbations present in the simulation indicates major disagreements with the measured travel-time shifts. These findings do not substantially change with the application of a correction for the reduction of wave amplitudes in the simulated and real sunspots. Overall, our findings demonstrate the need for new methods for inferring the subsurface structure of sunspots through helioseismic inversions.

  4. Nonsymmetrized hyperspherical harmonics with realistic NN potentials

    CERN Document Server

    Deflorian, Sergio; Leidemann, Winfried; Orlandini, Giuseppina

    2012-01-01

    The Schroedinger equation is solved for an A-nucleon system using an expansion of the wave function in nonsymmetrized hyperspherical harmonics. Our approach is both an extension and a modification of the formalism developed by Gattobigio et al.. The extension consists in the inclusion of spin and isospin degrees of freedom such that a calculation with more realistic NN potential models becomes possible, whereas the modification allows a much simpler determination of the fermionic ground state. The approach is applied to four- and six-body nuclei (4He, 6Li) with various NN potential models. It is shown that the results for ground-state energy and radius agree well with those from the literature.

  5. Presupernova neutrinos: realistic emissivities from stellar evolution

    Science.gov (United States)

    Patton, Kelly; Lunardini, Cecilia; Farmer, Rob; Timmes, Frank

    2017-01-01

    We present a calculation of neutrino emissivities and energy spectra from a presupernova, a massive star going through the advanced stages of nuclear burning before becoming a supernova. Neutrinos produced from beta decay and electron capture, as well as pair annihilation, plasmon decay, and the photoneutrino process are included. We use the state of the art stellar evolution code MESA to obtain realistic conditions for temperature, density, electron fraction, and nuclear isotopic composition. We have found that beta processes contribute significantly to the neutrino flux at potentially detectable energies of a few MeV. Estimates for the number of events at several current and future detectors are presented for the last few hours before collapse.

  6. Realistic Real World Contexts: Model Eliciting Activities

    Science.gov (United States)

    Doruk, Bekir Kürsat

    2016-01-01

    Researchers have proposed a variety of methods to make a connection between real life and mathematics so that it can be learned in a practical way and enable people to utilise mathematics in their daily lives. Model-eliciting activities (MEAs) were developed to fulfil this need and are very capable of serving this purpose. The reason MEAs are so…

  7. 大型并网光伏发电系统方案设计探讨%Discussion on the Design of Large-scale Grid-connected Photovoltaic Power Generation System

    Institute of Scientific and Technical Information of China (English)

    马春兰

    2015-01-01

    As a non-exhausted and clean energy source, the solar energy attracts worldwide attention nowadays.A grid-connected photovoltaic power generation project located in the Ruoqiang Industry Park is presented, including the design of photovoltaic power generation system and the optimization scheme, which could be a useful reference for similar pro-jects.%太阳能作为一种永不枯竭、无污染的清洁能源,已经越来越受到科技工作者们的重视,各国也在努力开发和利用太阳能。以若羌产业园区光伏并网项目为依托,介绍了光伏发电站的发电系统方案设计及其优化设计,可供类似工程参考。

  8. STEAMakers- a global initiative to connect STEM career professionals with the public to inspire the next generation and nurture a creative approach to science, technology, maths & engineering

    Science.gov (United States)

    Shaw, Niamh; Sorkhabi, Elburz; Gasquez, Oriol; Yajima, Saho

    2016-04-01

    STEAMakers is a global initiative founded by Niamh Shaw, Elburz Sorkhabi, Oriol Gasquez & Saho Yajima, four alumni of The International Space University's Space Studies Programme 2015 who each shared a vision to inspire the next generation to embrace science, technology, engineering & maths (STEM) in new ways, by embedding the Arts within STEM, putting the 'A' in STEAM. STEAMakers invited STEM professionals around the world to join their community, providing training and a suite of STEAM events, specially designed to encourage students to perceive science, technology, engineering & maths as a set of tools with which to create, design, troubleshoot, innovate, and imagine. The ultimate goal of STEAMakers is to grow this community and create a global culture of non-linear learning among the next generation, to nurture within them a new multidisciplinary mindset and incubate new forms of innovation and thought leadership required for the future through the power of inspiration and creativity.

  9. Biomass and bio-fuel based poly-generation for off-grid and grid-connected operation. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    2012-07-01

    The overall objective of this project was to design and build a combined heat and power plant based on an updraft gasifier and a 35 kW electrical output Stirling engine and further to test the flexibility of the plant with regards to fuel and application. In the project a containerized combined heat and power plant including a 200 kW updraft gasifier and a 35 kW electrical output Stirling engine was designed, the specified components were procured, the plant was installed in the three containers and the plant was erected at Amagerforbraendingen ready for the COP15 in November 2009. The potential of operating the Stirling engine in island-mode (without grid connection) was investigated by mathematical modelling. Using an absorption cooling plant connected to the Stirling CHP plant was also investigated. A technical feasibility study was undertaken and it was concluded that from the two available technologies (water/LiBr and Ammonia/water) the appropriate choice is depending on the required cooling temperature. Test runs focussed on investigating the fuel flexibility of two different configurations of Stirling engine CHP plants were carried out - respectively the updraft gasifier plant (the containerized plant and the DTU plant) and the pyrolysis plant (the plant situated at Barritskov). In order to perform these test runs a stable operation is required. On both the containerized plant and the pyrolysis plant this proved to be more challenging than expected and therefore the number of fuels tested was limited to willow chips at the containerized plant and dry wood residues, wood pellets and straw pellets on the pyrolysis plant. For all tested fuels it was possible to operate the plants, however different issues mainly related to the quality of the fuels were encountered. And so it can be concluded that the quality of the fuel is critical for the operation of both the updraft gasifier plant and the pyrolysis plant. A comprehensive desktop evaluation of the feasibility

  10. Realist trials and the testing of context-mechanism-outcome configurations: a response to Van Belle et al.

    Science.gov (United States)

    Bonell, Chris; Warren, Emily; Fletcher, Adam; Viner, Russell

    2016-10-01

    Van Belle et al. argue that our attempt to pursue realist evaluation via a randomised trial will be fruitless because we misunderstand realist ontology (confusing intervention mechanisms with intervention activities and with statistical mediation analyses) and because RCTs cannot comprehensively examine how and why outcome patterns are caused by mechanisms triggered in specific contexts. Through further consideration of our trial methods, we explain more fully how we believe complex social interventions work and what realist evaluation should aim to do within a trial. Like other realists, those undertaking realist trials assume that: social interventions provide resources which local actors may draw on in actions that can trigger mechanisms; these mechanisms may interact with contextual factors to generate outcomes; and data in the 'empirical' realm can be used to test hypotheses about mechanisms in the 'real' realm. Whether or not there is sufficient contextual diversity to test such hypotheses is a contingent not a necessary feature of trials. Previous exemplars of realist evaluation have compared empirical data from intervention and control groups to test hypotheses about real mechanisms. There is no inevitable reason why randomised trials should not also be able to do so. Random allocation merely ensures the comparability of such groups without necessarily causing evaluation to lapse from a realist into a 'positivist' or 'post-positivist' paradigm. Realist trials are ontologically and epistemologically plausible. Further work is required to assess whether they are feasible and useful but such work should not be halted on spurious philosophical grounds.

  11. 光伏组件倾斜角对并网发电影响的研究%Research on the Influence of the Inclination Angle of Solar Module to PV Grid-Connected Generation

    Institute of Scientific and Technical Information of China (English)

    王帅杰

    2014-01-01

    Solar PV generation has been developing rapidly from the beginning of 21 th century in China and other countries. Contrast to the stand-alone system,PV grid-connected system has more economic superiority,which leads to the trend of development in the future. The inclination angle of solar module has great impact on the quantity and price of electricity generated in the full year. This paper analyzes and describes the influence of the inclination angle of solar module to PV Grid-connected system based on solar radiation data obtained from a certain region.%以某地太阳能辐射量数据为基础,研究了光伏组件倾斜角对并网发电的影响,并根据所得数据进行了光资源计算和年度发电量分析,得出结论:以最佳倾斜角为基点,偏离5°以内对发电量影响为0.2%~0.4%,偏离10°左右时对发电量影响为0.7%~1.4%,偏离15°左右时对发电量影响为2.8%~7.8%。

  12. THE STUDY ON PV GRID CONNECTED GENERATION SYSTEM BASED ON ANALYTIC INVERSE CONTROL OF CURRENT%基于电流解析逆控制的光伏并网发电系统研究

    Institute of Scientific and Technical Information of China (English)

    王新; 张耀明; 李小燕; 郑飞

    2011-01-01

    Hie model of PV grid connected inverter generation system under synchronous rotating coordinate frame (dq) is three order, multivariate and couple nonlinear system, in this paper, the invertibility of the current dynamic system was analyzed firstly, the analytic inverse system was deduced, and the coupling between the two current components was cancelled, which make easy to realize the high static and dynamic performance control. And then the DC link voltage regulator was designed, the PV grid connected inverter generation system structure based on current analytic inverse control was proposed. At last, the simulation study of the system was done with the Matlah/Simulink, the performance of the proposed system was verified.%首先采用解析逆系统理论对模型电流动态环节的可逆性进行了分析,推导出解析逆系统,消除了电流分量之间的耦合,从而实现电流环的高动、静态性能控制.然后设计了直流母线电压调节器,提出了基于电流解析逆控制的光伏并网逆变发电系统结构.最后,采用Matlab/Simulink对整个系统进行仿真研究,验证了所提系统结构的有效性.

  13. Grid-connected Technology for Two Stages Hybrid PV-wind Generation System with Double Input%采用双输入两级式风光互补发电的并网技术

    Institute of Scientific and Technical Information of China (English)

    於锋; 胡国文

    2011-01-01

    A new Buck/Buck-Boost DC chopper circuit for hybrid PV-wind generation system is proposed and variable step perturbation method is used to achieve the maximum power point tracking (MPPT) on the basis of the proposed circuit. Grid-connected side, a new design method of grid-connected combinating dynamic reactive power compensation and active power filter is presented which based onip-iq current detection method of instaneous reactive power theory.From the simulation results, it is demonstrated that the proposed DC chopper circuit is enable to achieve the MPPT of the input side on the power system isimultaneously or individually. The proposed grid-connected scheme can achieve hybrid PV-wind generation and can also improve power quality effectively.%提出了一种新颖的供风光互补发电系统发电侧输入的升降压直流斩波电路.在该电路基础上,通过变步长扰动法实现对系统的最大功率点跟踪(MPPT).在其并网侧,基于瞬时无功理论的i-i电流检测法,成功实现了具有动态无功补偿、有源滤波功能的并网发电技术.仿真结果表明,所设计的直流斩波电路能够同时或独立地对发电系统输入端进行MPPT,所提出的并网方案在实现风光互补并网发电的同时,有效改善了电能质量.

  14. 具有限定功率运行的永磁直驱风力发电并网控制设计%Grid-connected control design for directly-driven PM wind generation with limited power operation

    Institute of Scientific and Technical Information of China (English)

    任碧莹; 同向前; 孙向东

    2014-01-01

    当风力发电或光伏电站这些间歇式可再生能源因外界环境影响而出力过高时,会使得配网系统潮流发生变化,并网处电压会超出运行的安全限值范围。为使系统处于可控范围,可对这些能源进行实时容量限制。对直驱式永磁同步风力发电系统的控制策略进行了研究,分析了风机输出功率曲线,设计了最大风能跟踪和限定功率运行输出的控制方法和系统后级逆变并网控制方法,使得风力发电系统具有最大功率跟踪或限定功率运行、并网有功/无功功率独立控制等功能。最后建立了风力发电并网系统仿真模型,仿真结果对所设计控制策略进行了验证。%When the intermittent renewable energies, such as wind generation or PV plant, generate more powers under the condition of the environmental influence, the tidal current of the distribution network will change and the voltage at the connected-grid point may exceed the safe limited range. In order to avoid the above phenomenon, it could be done to limit the output energy for these power generation systems. The control methods for the directly-driven permanent magnet (PM) wind generation system are studied, output power curves of the wind turbine are analyzed, control methods of the optimal wind-energy tracking or limiting power operation and end-stage control strategy of the system are designed. This makes wind generation system and PV generation system have the functions of MPPT or limiting power operation, and independent control of grid-connected active power and reactive power. At last, the simulation model of wind generation system is built, and the control strategy is verified by the simulation results.

  15. A Data-Driven Approach to Realistic Shape Morphing

    KAUST Repository

    Gao, Lin

    2013-05-01

    Morphing between 3D objects is a fundamental technique in computer graphics. Traditional methods of shape morphing focus on establishing meaningful correspondences and finding smooth interpolation between shapes. Such methods however only take geometric information as input and thus cannot in general avoid producing unnatural interpolation, in particular for large-scale deformations. This paper proposes a novel data-driven approach for shape morphing. Given a database with various models belonging to the same category, we treat them as data samples in the plausible deformation space. These models are then clustered to form local shape spaces of plausible deformations. We use a simple metric to reasonably represent the closeness between pairs of models. Given source and target models, the morphing problem is casted as a global optimization problem of finding a minimal distance path within the local shape spaces connecting these models. Under the guidance of intermediate models in the path, an extended as-rigid-as-possible interpolation is used to produce the final morphing. By exploiting the knowledge of plausible models, our approach produces realistic morphing for challenging cases as demonstrated by various examples in the paper. © 2013 The Eurographics Association and Blackwell Publishing Ltd.

  16. Simulation of realistic instrument noise for GRACE follow-on.

    Science.gov (United States)

    Ellmer, Matthias; Mayer-Gürr, Torsten

    2014-05-01

    Computer simulations have been an indispensable tool in assessing and predicting the performance of gravity recovery satellite missions, both present and future. Future satellite missions like GRACE follow-on will measure Earth's gravity with a much higher precision than their predecessors. This increased precision makes it necessary to reevaluate the applicability of current simulation strategies to future gravity missions. In past simulation efforts, effects that are known to be relevant factors for mission performance are often approximated or modeled incompletely. One such effect is the noise applied to simulated observables like precise orbits or K-Band ranges. These noisy observables are generated by adding simple white noise of a specific power to noise-free raw measurements. The noisy observables are then used in closed-loop simulations to quantify the performance of specific instruments, or a mission scenario as a whole. This work presents strategies to generate more realistic noise for satellite missions as implemented in the GROOPS (Gravity Recovery Object Orientated Programming System) software package. A generic interface for different noise generators is implemented in GROOPS. This interface is used to add different types of noise, such as white noise, colored or correlated noise, or noise with a given power spectral density to generated observables. It is thus possible to study the effect of the chosen noise model on the generated observable, and conversely the recovered gravity field as a whole. A better knowledge of the noise characteristics of the instruments on GRACE and GRACE follow-on will allow us to improve our understanding of their complex interactions. It will also allow us to improve our processing strategies for both simulated and real data, and will thus lead to a more precise and better understood recovered gravity field.

  17. The realistic meaning of Larry’s image in The Razor’s Edge

    Institute of Scientific and Technical Information of China (English)

    王国婧

    2015-01-01

    Larry, a character in the novel The Razor's Edge written by British novelist Maugham, was shocked in the First World War and went into a way of exploring the meaning of life. In this paper, the author ana-lyzed the image of Larry as a free explorer and a selfless rescuer so as to probe into the image of Larry further and researched its corresponding realistic meaning; especially his image played an important role in guiding the explorative generation after the Second World War and representing the modern people in the realistic society. Larry surmounted the boundaries of the time and space, which revealed the plight of the people and showed a way of ideal life with realistic meaning.

  18. 同步发电机模型在MMC并网控制中的应用%Application of Synchronous Generator's Model in Grid-connected Control of MMC

    Institute of Scientific and Technical Information of China (English)

    刘喜梅; 陈朋; 张群; 赵倩

    2013-01-01

    为了实现模块化多电平换流器MMC (modular multilevel converter)快速、平滑并网,该文将同步发电机模型与同步发电机准同步并网原理应用于MMC并网控制.先对同步发电机进行建模,根据MMC的原理及其控制原则确定控制策略,并结合同步发电机模型设计控制器控制MMC输送到电网的功率,实现功率跟踪;引入同步发电机准同步并网原理,根据锁相环PLL (phase locked loop)检测到的电网电压与MMC输出电压的相位信息自动搜寻最佳合闸时间,控制MMC在最佳时刻平滑并入电网,实现友好并网.MATLAB/Simulink仿真结果验证了该控制策略的正确性和有效性.%In order to realize modular multilevel converter (MMC) grid-connected fast and smoothly, the model and quasi synchronous principle of synchronous generator is applied to control MMC in this paper. First, a model of synchronous generator is built, and a control strategy is determined according to the theory and control principle of MMC, and a controller is designed with the model of synchronous generator to control MMC conveying power to the grid and realize power tracking. The quasi synchronous principle of synchronous generator is introduced to search the optimal switching time according to the phase of grid voltage and MMC output voltage detected by PLL, and control MMC to connect with grid smoothly at the optimal time to realize grid-connected friendly. Simulation results of MATLAB/ simulink verify the correctness and effectiveness of this control strategy.

  19. By-law from July 4, 2003, relative to the technical prescriptions of design and operation for the connection of a power generating facility to the public power transportation grid; Arrete du 4 juillet 2003 relatif aux prescriptions techniques de conception et de fonctionnement pour le raccordement au reseau public de transport d'une installation de production d'energie electrique

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-09-01

    This by-law fixes the constructive and organisational dispositions that must fulfill the power generating facilities in order to make their connection to the public power grid conformable with the objectives of the decree from June 27, 2003. The dispositions concern: the voltage, connection scheme, protection systems, earthing, domain of operation, frequency adjustment and quality of current, communication and remote control systems of the power generating facility. (J.S.)

  20. 面向综合负荷的并网光伏发电系统等效建模%Equivalent Modeling of Grid-connected Photovoltaic Power Generation Systems for Comprehensive Load

    Institute of Scientific and Technical Information of China (English)

    李培强; 曾小军; 黄际元; 童莹; 张晓敏; 张立

    2016-01-01

    A simulation system for the grid-connected photovoltaic (PV) power generation system is developed based on the MATLAB/Simulink and the physical mechanism of the PV cells.The influence of the grid-connected PV power generation system on the comprehensive load characteristic of distribution network is studied.And several equivalent models available to the PV power generation system are analyzed and compared.On this basis,a new equivalent model based on transfer functions for the PV power generation system is proposed.The model has a simple structure,less parameters,and can effectively describe the output limit of PV power generation system.At the same time,it is easy to implement in the power system simulation software.A generalized comprehensive load model is developed by paralleling the conventional comprehensive load model with the new equivalent model to describe the characteristic of the comprehensive load containing PV power generation systems.Simulation results show that the generalized comprehensive load model has good generalization ability and stable identification parameters,while meeting the need of engineering simulation.%基于 MATLAB/Simulink 和光伏电池自身的物理机理搭建了并网光伏发电的仿真系统,研究了其对配电网综合负荷特性的影响因素,分析比较了已有光伏发电系统等效模型的优劣。在此基础上构建了光伏发电系统传递函数等效模型,该模型具有结构简单、参数少、能有效描述光伏发电系统的出力极限等优点,同时易于在电力系统仿真软件中实现。采用所提出的等效模型与传统综合负荷模型并联,构建广义综合负荷模型,对含光伏发电系统的综合负荷进行建模,仿真实践表明此广义综合负荷模型具有良好的泛化能力,辨识参数稳定,能够满足工程仿真的需要。

  1. Performance of Airborne Precision Spacing Under Realistic Wind Conditions

    Science.gov (United States)

    Wieland, Frederick; Santos, Michel; Krueger, William; Houston, Vincent E.

    2011-01-01

    With the expected worldwide increase of air traffic during the coming decade, both the Federal Aviation Administration s (FAA s) Next Generation Air Transportation System (NextGen), as well as Eurocontrol s Single European Sky ATM Research (SESAR) program have, as part of their plans, air traffic management solutions that can increase performance without requiring time-consuming and expensive infrastructure changes. One such solution involves the ability of both controllers and flight crews to deliver aircraft to the runway with greater accuracy than is possible today. Previous research has shown that time-based spacing techniques, wherein the controller assigns a time spacing to each pair of arriving aircraft, is one way to achieve this goal by providing greater runway delivery accuracy that produces a concomitant increase in system-wide performance. The research described herein focuses on a specific application of time-based spacing, called Airborne Precision Spacing (APS), which has evolved over the past ten years. This research furthers APS understanding by studying its performance with realistic wind conditions obtained from atmospheric sounding data and with realistic wind forecasts obtained from the Rapid Update Cycle (RUC) short-range weather forecast. In addition, this study investigates APS performance with limited surveillance range, as provided by the Automatic Dependent Surveillance-Broadcast (ADS-B) system, and with an algorithm designed to improve APS performance when an ADS-B signal is unavailable. The results presented herein quantify the runway threshold delivery accuracy of APS un-der these conditions, and also quantify resulting workload metrics such as the number of speed changes required to maintain spacing.

  2. A Straightforward Convergence Method for ICCG Simulation of Multiloop and Time-Stepping FE Model of Synchronous Generators with Simultaneous AC and Rectified DC Connections

    Directory of Open Access Journals (Sweden)

    Shanming Wang

    2015-01-01

    Full Text Available Now electric machines integrate with power electronics to form inseparable systems in lots of applications for high performance. For such systems, two kinds of nonlinearities, the magnetic nonlinearity of iron core and the circuit nonlinearity caused by power electronics devices, coexist at the same time, which makes simulation time-consuming. In this paper, the multiloop model combined with FE model of AC-DC synchronous generators, as one example of electric machine with power electronics system, is set up. FE method is applied for magnetic nonlinearity and variable-step variable-topology simulation method is applied for circuit nonlinearity. In order to improve the simulation speed, the incomplete Cholesky conjugate gradient (ICCG method is used to solve the state equation. However, when power electronics device switches off, the convergence difficulty occurs. So a straightforward approach to achieve convergence of simulation is proposed. At last, the simulation results are compared with the experiments.

  3. Realistic Scheduling Mechanism for Smart Homes

    Directory of Open Access Journals (Sweden)

    Danish Mahmood

    2016-03-01

    Full Text Available In this work, we propose a Realistic Scheduling Mechanism (RSM to reduce user frustration and enhance appliance utility by classifying appliances with respective constraints and their time of use effectively. Algorithms are proposed regarding functioning of home appliances. A 24 hour time slot is divided into four logical sub-time slots, each composed of 360 min or 6 h. In these sub-time slots, only desired appliances (with respect to appliance classification are scheduled to raise appliance utility, restricting power consumption by a dynamically modelled power usage limiter that does not only take the electricity consumer into account but also the electricity supplier. Once appliance, time and power usage limiter modelling is done, we use a nature-inspired heuristic algorithm, Binary Particle Swarm Optimization (BPSO, optimally to form schedules with given constraints representing each sub-time slot. These schedules tend to achieve an equilibrium amongst appliance utility and cost effectiveness. For validation of the proposed RSM, we provide a comparative analysis amongst unscheduled electrical load usage, scheduled directly by BPSO and RSM, reflecting user comfort, which is based upon cost effectiveness and appliance utility.

  4. Towards a realistic description of hadron resonances

    Science.gov (United States)

    Schmidt, R. A.; Canton, L.; Schweiger, W.; Plessas, W.

    2016-08-01

    We report on our attempts of treating excited hadron states as true quantum resonances. Hitherto the spectroscopy of mesons, usually considered as quark-antiquark systems, and of baryons, usually considered as three-quark systems, has been treated through excitation spectra of bound states (namely, confined few-quark systems), corresponding to poles of the quantum-mechanical resolvent at real negative values in the complex energy plane. As a result the wave functions, i.e. the residua of the resolvent, have not exhibited the behaviour as required for hadron resonances with their multiple decay modes. This has led to disturbing shortcomings in the description of hadronic resonance phenomena. We have aimed at a more realistic description of hadron resonances within relativistic constituent-quark models taking into account explicitly meson-decay channels. The corresponding coupled-channels theory is based on a relativistically invariant mass operator capable of producing hadron ground states with real energies and hadron resonances with complex energies, the latter corresponding to poles in the lower half-plane of the unphysical sheet of the complex energy plane. So far we have demonstrated the feasibility of the coupled-channels approach to hadron resonances along model calculations producing indeed the desired properties. The corresponding spectral properties will be discussed in this contribution. More refined studies are under way towards constructing a coupled-channels relativistic constituent-quark model for meson and baryon resonances.

  5. Pricing European Options in Realistic Markets

    CERN Document Server

    Schaden, M

    2002-01-01

    We investigate the relation between the fair price for European-style vanilla options and the distribution of short-term returns on the underlying asset ignoring transaction and other costs. We compute the risk-neutral probability density conditional on the total variance of the asset's returns when the option expires. If the asset's future price has finite expectation, the option's fair value satisfies a parabolic partial differential equation of the Black-Scholes type in which the variance of the asset's returns rather than a trading time is the evolution parameter. By immunizing the portfolio against large-scale price fluctuations of the asset, the valuation of options is extended to the realistic case\\cite{St99} of assets whose short-term returns have finite variance but very large, or even infinite, higher moments. A dynamic Delta-hedged portfolio that is statically insured against exceptionally large fluctuations includes at least two different options on the asset. The fair value of an option in this c...

  6. Determination of Realistic Fire Scenarios in Spacecraft

    Science.gov (United States)

    Dietrich, Daniel L.; Ruff, Gary A.; Urban, David

    2013-01-01

    This paper expands on previous work that examined how large a fire a crew member could successfully survive and extinguish in the confines of a spacecraft. The hazards to the crew and equipment during an accidental fire include excessive pressure rise resulting in a catastrophic rupture of the vehicle skin, excessive temperatures that burn or incapacitate the crew (due to hyperthermia), carbon dioxide build-up or accumulation of other combustion products (e.g. carbon monoxide). The previous work introduced a simplified model that treated the fire primarily as a source of heat and combustion products and sink for oxygen prescribed (input to the model) based on terrestrial standards. The model further treated the spacecraft as a closed system with no capability to vent to the vacuum of space. The model in the present work extends this analysis to more realistically treat the pressure relief system(s) of the spacecraft, include more combustion products (e.g. HF) in the analysis and attempt to predict the fire spread and limiting fire size (based on knowledge of terrestrial fires and the known characteristics of microgravity fires) rather than prescribe them in the analysis. Including the characteristics of vehicle pressure relief systems has a dramatic mitigating effect by eliminating vehicle overpressure for all but very large fires and reducing average gas-phase temperatures.

  7. Sialendoscopy Training: Presentation of a Realistic Model.

    Science.gov (United States)

    Pascoto, Gabriela Robaskewicz; Stamm, Aldo Cassol; Lyra, Marcos

    2017-01-01

    Introduction Several surgical training simulators have been created for residents and young surgeons to gain experience with surgical procedures. Laboratory training is fundamental for acquiring familiarity with the techniques of surgery and skill in handing instruments. Objective The aim of this study is to present a novel simulator for training sialendoscopy. Method This realistic simulator was built with a synthetic thermo-retractile, thermo-sensible rubber which, when combined with different polymers, produces more than 30 different formulas. These formulas present textures, consistencies, and mechanical resistance are similar to many human tissues. Results The authors present a training model to practice sialendoscopy. All aspects of the procedure are simulated: month opening, dilatation of papillae, insert of the scope, visualization of stones, extraction of these stones with grasping or baskets, and finally, stone fragmentation with holmium laser. Conclusion This anatomical model for sialendoscopy training should be considerably useful to abbreviate the learning curve during the qualification of young surgeons while minimizing the consequences of technical errors.

  8. Cerebral blood flow simulations in realistic geometries

    Directory of Open Access Journals (Sweden)

    Szopos Marcela

    2012-04-01

    Full Text Available The aim of this work is to perform the computation of the blood flow in all the cerebral network, obtained from medical images as angiographies. We use free finite elements codes as FreeFEM++. We first test the code on analytical solutions in simplified geometries. Then, we study the influence of boundary conditions on the flow and we finally perform first computations on realistic meshes. L’objectif est ici de simuler l’écoulement sanguin dans tout le réseau cérébral (artériel et veineux obtenu à partir d’angiographies cérébrales 3D à l’aide de logiciels d’éléments finis libres, comme FreeFEM++. Nous menons d’abord une étude détaillée des résultats sur des solutions analytiques et l’influence des conditions limites à imposer dans des géométries simplifiées avant de travailler sur les maillages réalistes.

  9. Design of 1.1 MW Solar Energy PV Electricity Generation and Grid Connected System%1.1MW太阳能光伏发电并网系统的设计

    Institute of Scientific and Technical Information of China (English)

    陆建国; 张竟若; 唐风芹; 汤士敏

    2011-01-01

    随着光伏技术的不断成熟,太阳能光伏发电正由补充能源逐渐向替代能源过度.常州科教城太阳能光伏发电并网系统主要包含TSM - 230PC05光伏组件、PVS -8防雷汇流箱、PMB型直流防雷配电柜、SG100K3型逆变器、升压站及并网接入系统、光伏发电展示系统和电网调度通讯系统.讨论了主要设备的选型、并网接入点的选择和提高光伏并网电能质量的措施等相关技术问题.实际运行表明,主要参数符合国标规定,系统运行平稳,达到了使用要求.%While technology for solar photovoltaic technology is becoming more and more mature, solar photovoltaic power generation system has been transferring from traditional supplementary energy to emerging substitutes . A solar energy PV electricity generation and system is developed in Changzhou science and technology & education city. It consists of many parts, such as TSM - 230PC05 PV modules, PVS - 8 convergence boxes for lighting protection, PMB current power distribution cabinets, SG100K3 inverters, boosting stations, grid connected system, PV electricity generation display system, and power network control and communication system, etc. Some correlation techniques were discussed, such as type selection of main equipments, point selection of grid connection, and measures for improving electrical energy quality of PV grid connected , etc. Actual motion shows that system key parameters are in line with the set of national standard, and system run smoothly. This design meets the need of utilization.

  10. Improving Transient Stability in a Grid-Connected Squirrel-Cage Induction Generator Wind Turbine System Using a Fuzzy Logic Controller

    Directory of Open Access Journals (Sweden)

    Minh Quan Duong

    2015-06-01

    Full Text Available A common problem in wind power plants involves fixed-speed wind turbines. In fact, being equipped with a squirrel-cage induction generator (SCIG, they tend to drain a relevant amount of reactive power from the grid, potentially causing voltage drops and possible voltage instability. To improve SCIG power quality and transient stability, this paper investigates a new control strategy for pitch angle control based on proportional-integral (PI controller and a fuzzy logic controller (FLC, considering both normal and fault ride-through (FRT schemes. In the literature, often, the mechanical torque output is assumed constant for a specific wind speed. This might not be accurate, because the mechanical torque-speed typical of a wind turbine depends also on the power coefficient or pitch angle. In this paper, an analytic model of transient stability is proposed using the equivalent circuit of the SCIG and using the concepts of stable and unstable electrical-mechanical equilibrium. The method has been evaluated by comparing the results obtained by the analytic method with the dynamic simulation. The results show that the proposed hybrid controller is effective at smoothing the output power and complying with FRT requirements for SCIG in the power system.

  11. Realistic modeling of seismic input for megacities and large urban areas

    Science.gov (United States)

    Panza, G. F.; Unesco/Iugs/Igcp Project 414 Team

    2003-04-01

    The project addressed the problem of pre-disaster orientation: hazard prediction, risk assessment, and hazard mapping, in connection with seismic activity and man-induced vibrations. The definition of realistic seismic input has been obtained from the computation of a wide set of time histories and spectral information, corresponding to possible seismotectonic scenarios for different source and structural models. The innovative modeling technique, that constitutes the common tool to the entire project, takes into account source, propagation and local site effects. This is done using first principles of physics about wave generation and propagation in complex media, and does not require to resort to convolutive approaches, that have been proven to be quite unreliable, mainly when dealing with complex geological structures, the most interesting from the practical point of view. In fact, several techniques that have been proposed to empirically estimate the site effects using observations convolved with theoretically computed signals corresponding to simplified models, supply reliable information about the site response to non-interfering seismic phases. They are not adequate in most of the real cases, when the seismic sequel is formed by several interfering waves. The availability of realistic numerical simulations enables us to reliably estimate the amplification effects even in complex geological structures, exploiting the available geotechnical, lithological, geophysical parameters, topography of the medium, tectonic, historical, palaeoseismological data, and seismotectonic models. The realistic modeling of the ground motion is a very important base of knowledge for the preparation of groundshaking scenarios that represent a valid and economic tool for the seismic microzonation. This knowledge can be very fruitfully used by civil engineers in the design of new seismo-resistant constructions and in the reinforcement of the existing built environment, and, therefore

  12. 光伏发电并网及其相关技术发展现状与展望%The Development Status and Prospect of Grid-connected Photovoltaic Generation and Its Related Technologies

    Institute of Scientific and Technical Information of China (English)

    艾欣; 韩晓男; 孙英云

    2013-01-01

    介绍了光伏发电的优势及发展方向,着重阐述了国内外光伏发电技术的发展现状及前景.鉴于光伏发电出力的随机性和不连续性,最大功率点跟踪技术(MPPT)一直都是研究重点,随着光伏技术的发展,MPPT也为了满足新的要求而不断发展,一些改进方法应运而生,以提高系统稳定性并适应各种运行条件.光伏电站并入电网运行会对电网造成多方面影响,例如孤岛效应、谐波污染、无功补偿、电压闪变等问题,随着光伏电站容量的增大,上述问题更是迫切需要解决,本文总结了一些目前用于解决这些问题的方法.逆变器是光伏发电并网的关键技术,在这方面本文叙述了并网逆变器的功能,拓扑结构的发展、有待解决的问题以及大型光伏电站并网逆变器的发展趋势.%In this paper, the principle of photovoltaic (PV) power generation is introduced briefly, the advantage and development trend of PV are also discussed, and the development status and the prospects of photovoltaic generation and grid-connected technology at home and abroad are mainly demonstrated. Due to the randomness and discontinuity of the output of photovoltaic generation, maximum power point tracking (MPPT) has always been the hot topic. With the development of photovoltaic technology, to meet new requirements, some improved MPPT methods have been presented, which can not only enhance the system stability, but also be applied to numerous operating conditions. The grid-connected photovoltaic plant will have impact on the power grid, such as the islanding effect, the problem of harmonic pollution, reactive power compensation and voltage flicker. With the capacity increasing of photovoltaic plants, the above influences need to be solved urgently, so some current countermeasures are concluded. The inverter is the key technology of grid-connected PV system. In this paper, the functions and requirements of the grid-connected inverter

  13. Simulation of Distributed Generation Connected to Distribution Network and Harmonic Analysis%分布式电源接入配电网的仿真与谐波分析

    Institute of Scientific and Technical Information of China (English)

    朱旭; 陈武; 赵波; 窦晓波; 吴在军; 顾伟

    2016-01-01

    To analyze the harmonic characteristics of distributed generation of high penetration connected to the large distribution network, the mathematical model and simulation model of grid-connected photovoltaic system and grid-connected wind power system are introduced and several photovoltaic cells and wind turbines are taken into the IEEE 30 bus test system to be simulated in PSCAD/EMTDC. Through fast Fourier transformation (FFT) analysis of node voltage and branch current which are measured, the factors which affect total harmonic distortion of voltage and current are found.%为分析高渗透率情况下的分布式电源接入规模较大的配电网的谐波特性,介绍光伏发电并网系统和风力发电并网系统的数学模型和仿真模型,在PSCAD/EMTDC中将多组光伏电池和风力发电机接入IEEE 30节点标准测试系统进行仿真。测量相应的节点电压和支路电流,对测量的节点电压和支路电流进行快速傅里叶变换(fast Fourier transformation,FFT)分析,得出了影响谐波电压畸变率的因素和影响谐波电流畸变率的因素。

  14. 基于并网光伏发电系统的反孤岛研究%Anti-Islanding Research Based on Photovoltaic Grid-Connected Generation System

    Institute of Scientific and Technical Information of China (English)

    肖建东; 于淼; 黄孝鹏; 沈友建; 陈煊之

    2015-01-01

    Solar photovoltaic grid generation is a kind of green energy and it is more and more used in the market However,in the process of its development the island fault as a common problem has discovered, how to detect the fault effectively is more and more important.The positive feedback active frequency drift is put forward in this paper can detect island failure timely,in order to verify the results,we use Matlab/simulink to simulat this method,you can see from the simulation results,this method can detect the phenomenon ef-fectively,and shorten the fault detection time.%太阳能光伏并网发电是一种绿色环保的电能,在市场中的应用也越来越多。然而在快速发展的过程中出现了孤岛故障这个较为普遍的问题,及时有效地检测出孤岛故障显得越来越重要。该文提出的正反馈主动式频率偏移法能够及时地检测孤岛故障。为了验证这一结果,用Matlab/simulink对该方法进行了仿真。从仿真结果中可以看到,此方法确实能够及时有效地检测出这一现象,而且缩短了故障检测时间。

  15. Realistic Detectability of Close Interstellar Comets

    Science.gov (United States)

    Cook, Nathaniel V.; Ragozzine, Darin; Granvik, Mikael; Stephens, Denise C.

    2016-07-01

    During the planet formation process, billions of comets are created and ejected into interstellar space. The detection and characterization of such interstellar comets (ICs) (also known as extra-solar planetesimals or extra-solar comets) would give us in situ information about the efficiency and properties of planet formation throughout the galaxy. However, no ICs have ever been detected, despite the fact that their hyperbolic orbits would make them readily identifiable as unrelated to the solar system. Moro-Martín et al. have made a detailed and reasonable estimate of the properties of the IC population. We extend their estimates of detectability with a numerical model that allows us to consider “close” ICs, e.g., those that come within the orbit of Jupiter. We include several constraints on a “detectable” object that allow for realistic estimates of the frequency of detections expected from the Large Synoptic Survey Telescope (LSST) and other surveys. The influence of several of the assumed model parameters on the frequency of detections is explored in detail. Based on the expectation from Moro-Martín et al., we expect that LSST will detect 0.001-10 ICs during its nominal 10 year lifetime, with most of the uncertainty from the unknown number density of small (nuclei of ˜0.1-1 km) ICs. Both asteroid and comet cases are considered, where the latter includes various empirical prescriptions of brightening. Using simulated LSST-like astrometric data, we study the problem of orbit determination for these bodies, finding that LSST could identify their orbits as hyperbolic and determine an ephemeris sufficiently accurate for follow-up in about 4-7 days. We give the hyperbolic orbital parameters of the most detectable ICs. Taking the results into consideration, we give recommendations to future searches for ICs.

  16. On the realistic validation of photometric redshifts

    Science.gov (United States)

    Beck, R.; Lin, C.-A.; Ishida, E. E. O.; Gieseke, F.; de Souza, R. S.; Costa-Duarte, M. V.; Hattab, M. W.; Krone-Martins, A.

    2017-07-01

    Two of the main problems encountered in the development and accurate validation of photometric redshift (photo-z) techniques are the lack of spectroscopic coverage in the feature space (e.g. colours and magnitudes) and the mismatch between the photometric error distributions associated with the spectroscopic and photometric samples. Although these issues are well known, there is currently no standard benchmark allowing a quantitative analysis of their impact on the final photo-z estimation. In this work, we present two galaxy catalogues, Teddy and Happy, built to enable a more demanding and realistic test of photo-z methods. Using photometry from the Sloan Digital Sky Survey and spectroscopy from a collection of sources, we constructed data sets that mimic the biases between the underlying probability distribution of the real spectroscopic and photometric sample. We demonstrate the potential of these catalogues by submitting them to the scrutiny of different photo-z methods, including machine learning (ML) and template fitting approaches. Beyond the expected bad results from most ML algorithms for cases with missing coverage in the feature space, we were able to recognize the superiority of global models in the same situation and the general failure across all types of methods when incomplete coverage is convoluted with the presence of photometric errors - a data situation which photo-z methods were not trained to deal with up to now and which must be addressed by future large-scale surveys. Our catalogues represent the first controlled environment allowing a straightforward implementation of such tests. The data are publicly available within the COINtoolbox (https://github.com/COINtoolbox/photoz_catalogues).

  17. Calculation of 3-Dimensional Synthetic Seismograms on the Connection Machine

    Science.gov (United States)

    1989-10-01

    modes with direction to be visualized . The extensive calculations required for realistic size models stretches the resources of serial computers like...Output is to the Imagen laser printer (figure 6): RED-$ Oimg cbxz0200.img 3.4.2 Using the CM frame buffer The CM graphics display system (GDS... visualized . The extensive calculations required for realistic size models stretches the resources of serial computers like the VAX 8800. On the Connection

  18. Non-tachyonic semi-realistic non-supersymmetric heterotic-string vacua

    Energy Technology Data Exchange (ETDEWEB)

    Ashfaque, Johar M.; Athanasopoulos, Panos; Faraggi, Alon E.; Sonmez, Hasan [University of Liverpool, Department of Mathematical Sciences, Liverpool (United Kingdom)

    2016-04-15

    The heterotic-string models in the free fermionic formulation gave rise to some of the most realistic-string models to date, which possess N = 1 spacetime supersymmetry. Lack of evidence for supersymmetry at the LHC instigated recent interest in non-supersymmetric heterotic-string vacua. We explore what may be learned in this context from the quasi-realistic free fermionic models. We show that constructions with a low number of families give rise to proliferation of a priori tachyon producing sectors, compared to the non-realistic examples, which typically may contain only one such sector. The reason being that in the realistic cases the internal six dimensional space is fragmented into smaller units. We present one example of a quasi-realistic, non-supersymmetric, non-tachyonic, heterotic-string vacuum and compare the structure of its massless spectrum to the corresponding supersymmetric vacuum. While in some sectors supersymmetry is broken explicitly, i.e. the bosonic and fermionic sectors produce massless and massive states, other sectors, and in particular those leading to the chiral families, continue to exhibit Fermi-Bose degeneracy. In these sectors the massless spectrum, as compared to the supersymmetric cases, will only differ in some local or global U(1) charges. We discuss the conditions for obtaining n{sub b} = n{sub f} at the massless level in these models. Our example model contains an anomalous U(1) symmetry, which generates a tadpole diagram at one-loop order in string perturbation theory. We speculate that this tadpole diagram may cancel the corresponding diagram generated by the one-loop non-vanishing vacuum energy and that in this respect the supersymmetric and non-supersymmetric vacua should be regarded on an equal footing. Finally we discuss vacua that contain two supersymmetry generating sectors. (orig.)

  19. Non-tachyonic semi-realistic non-supersymmetric heterotic-string vacua

    Science.gov (United States)

    Ashfaque, Johar M.; Athanasopoulos, Panos; Faraggi, Alon E.; Sonmez, Hasan

    2016-04-01

    The heterotic-string models in the free fermionic formulation gave rise to some of the most realistic-string models to date, which possess N=1 spacetime supersymmetry. Lack of evidence for supersymmetry at the LHC instigated recent interest in non-supersymmetric heterotic-string vacua. We explore what may be learned in this context from the quasi-realistic free fermionic models. We show that constructions with a low number of families give rise to proliferation of a priori tachyon producing sectors, compared to the non-realistic examples, which typically may contain only one such sector. The reason being that in the realistic cases the internal six dimensional space is fragmented into smaller units. We present one example of a quasi-realistic, non-supersymmetric, non-tachyonic, heterotic-string vacuum and compare the structure of its massless spectrum to the corresponding supersymmetric vacuum. While in some sectors supersymmetry is broken explicitly, i.e. the bosonic and fermionic sectors produce massless and massive states, other sectors, and in particular those leading to the chiral families, continue to exhibit Fermi-Bose degeneracy. In these sectors the massless spectrum, as compared to the supersymmetric cases, will only differ in some local or global U(1) charges. We discuss the conditions for obtaining n_b=n_f at the massless level in these models. Our example model contains an anomalous U(1) symmetry, which generates a tadpole diagram at one-loop order in string perturbation theory. We speculate that this tadpole diagram may cancel the corresponding diagram generated by the one-loop non-vanishing vacuum energy and that in this respect the supersymmetric and non-supersymmetric vacua should be regarded on an equal footing. Finally we discuss vacua that contain two supersymmetry generating sectors.

  20. Realistic CT simulation using the 4D XCAT phantom.

    Science.gov (United States)

    Segars, W P; Mahesh, M; Beck, T J; Frey, E C; Tsui, B M W

    2008-08-01

    The authors develop a unique CT simulation tool based on the 4D extended cardiac-torso (XCAT) phantom, a whole-body computer model of the human anatomy and physiology based on NURBS surfaces. Unlike current phantoms in CT based on simple mathematical primitives, the 4D XCAT provides an accurate representation of the complex human anatomy and has the advantage, due to its design, that its organ shapes can be changed to realistically model anatomical variations and patient motion. A disadvantage to the NURBS basis of the XCAT, however, is that the mathematical complexity of the surfaces makes the calculation of line integrals through the phantom difficult. They have to be calculated using iterative procedures; therefore, the calculation of CT projections is much slower than for simpler mathematical phantoms. To overcome this limitation, the authors used efficient ray tracing techniques from computer graphics, to develop a fast analytic projection algorithm to accurately calculate CT projections directly from the surface definition of the XCAT phantom given parameters defining the CT scanner and geometry. Using this tool, realistic high-resolution 3D and 4D projection images can be simulated and reconstructed from the XCAT within a reasonable amount of time. In comparison with other simulators with geometrically defined organs, the XCAT-based algorithm was found to be only three times slower in generating a projection data set of the same anatomical structures using a single 3.2 GHz processor. To overcome this decrease in speed would, therefore, only require running the projection algorithm in parallel over three processors. With the ever decreasing cost of computers and the rise of faster processors and multi-processor systems and clusters, this slowdown is basically inconsequential, especially given the vast improvement the XCAT offers in terms of realism and the ability to generate 3D and 4D data from anatomically diverse patients. As such, the authors conclude

  1. Analysis on Grid-Connectible Capacity of Distributed PV Generation in Case of PV Generation Distribution Close to Load Distribution%分布式光伏电源与负荷分布接近条件下的可接入容量分析

    Institute of Scientific and Technical Information of China (English)

    刘健; 黄炜

    2015-01-01

    为了给分布式光伏电源接入规划提供科学决策依据,建立了负荷和分布式光伏电源在各种分布下所引起的电压偏差和电压波动数学模型。在此基础上,以分布式光伏电源引起的最大电压上偏差和最大电压波动以及无分布式光伏电源时单纯由负载引起的最大电压下偏差为约束条件,推导出了6种负荷和分布式光伏电源容量沿馈线相同分布条件下能够满足电压质量要求的分布式光伏电源允许接入容量范围。以城市配电网和农村配电网的典型参数为例对所提出方法进行了分析和说明,结果表明所建议方法是可行的,并且能够有效得出允许接入的分布式光伏电源的容量范围。%To offer reasonable foundation for the planning of grid-connection of distributed photovoltaic (PV) generations, the mathematical models for voltage deviation and voltage fluctuation caused by various distributions of loads and PV generations are established. Taking the maximum upper deviation of voltage and the maximum voltage fluctuation caused by distributed PV generations and the maximum lower voltage deviation caused by the load only when the PV generation does not exist as constraints, the capacity range of allowed grid-connected distributed PV generations, by which the demand on voltage quality can be met under six distribution conditions of load and distributed PV generations along the feeder, is derived. Taking typical parameters of urban distribution network and those of rural distribution network for example, the proposed method is analyzed and illustrated, results of the analysis show that the proposed method is feasible, and using the proposed method the allowed grid-connected capacity range of distributed PV generations can be determined.

  2. Design and implementation of energy saving controller for photovoltaic power generation grid-connected system%光伏发电中并网系统的节能控制器的设计与实现

    Institute of Scientific and Technical Information of China (English)

    褚新建

    2016-01-01

    The energy saving controller for photovoltaic power generation grid⁃connected system was designed and imple⁃mented. The design processes of hardware and software are presented. The optimal current value of the photovoltaic array output is obtained by means of the voltage and current values acquired from module analysis of the designed photovoltaic grid⁃connect⁃ed scheme. And then the current value is fed back to the grid⁃connected current management module to control the output cur⁃rent of grid⁃connected inverter in real time,so as to ensure it in the optimal status,and make the consumption of grid⁃connect⁃ed electric energy minimum. The wavelet analysis method is used to detect the islanding effect of the photovoltaic grid,regulate the grid⁃connected current positioning module for work ending,avoid the waste of energy,and realize the energy⁃saving control. The experiment results indicate that the energy⁃saving control effect of the designed controller is remarkable,and the controller can realize the balance of energy consumption.%设计并实现光伏发电中并网系统的节能控制器,给出硬件软件设计流程。设计光伏并网方案模块分析获取的电压电流值,得到光伏阵列输出的最佳电流值,将该值反馈到并网电流管理模块中,对并网变流器输出电流实时调控,确保其处于最佳状态,使得并网电能的消耗最低化。通过小波分析方法检测光伏电网孤岛效应,并调控并网电流定位模块终止工作,避免能量的浪费,实现节能控制。实验结果表明,所设计控制器节能控制效果显著,可实现能耗的均衡。

  3. 基于光伏并网的电能质量控制系统%A Power Quality Control System Based on Grid-Connected Photovoltaic Power Generation

    Institute of Scientific and Technical Information of China (English)

    王晓; 罗安; 邓才波; 帅智康; 孙运宾; 肖萍

    2012-01-01

    Considering the features of microgrid with grid-connected photovoltaic (PV) generation, a PV grid-connecting and power quality control system that not only can implement grid-connection of PV generation but also can implement reactive power compensation and filter harmonic currents is proposed. Firstly, the architecture and principle of the proposed system are presented and its mathematical model is built; then a dead-bead compound control strategy suitable to the proposed system is put forward, and theoretical calculation of pulse width modulation under the proposed control strategy is emphatically analyzed and the method to acquire compound instruction is given; finally, the simulation model and experimental platform for the proposed system are constructed and a concrete scheme to implement the proposed system is given. Operational data shows that the architecture and control strategy for the proposed system are effective and reasonable.%结合微网光伏并网系统和电能质量调节器的特点,提出了一种既能够并网发电,又能实现无功补偿和滤除电网谐波电流的光伏并网及电能质量控制系统(micro photovoltaic grid and power quality control system,MPG—PQC)结构。首先介绍了该系统的结构和原理,构建了该系统的数学模型;然后提出了适用于该系统的无差拍复合控制策略,重点分析了该控制策略下调制脉宽的理论计算,给出了复合指令的求取方法;最后,搭建了仿真模型和实验平台,给出了该系统的具体实现方案。运行数据表明了系统结构和控制策略的有效性和合理性。

  4. Partition-induced connections and operators for pattern analysis

    NARCIS (Netherlands)

    Ouzounis, Georgios K.; Wilkinson, Michael H.F.

    2010-01-01

    In this paper we present a generalization on the notion of image connectivity similar to that modeled by second-generation connections. The connected operators based on this new type of connection make use of image partitions aided by mask images to extract path-wise connected regions that were prev

  5. Realistic and interactive high-resolution 4D environments for real-time surgeon and patient interaction.

    Science.gov (United States)

    Smith, L N; Farooq, A R; Smith, M L; Ivanov, I E; Orlando, A

    2017-06-01

    Remote consultations that are realistic enough to be useful medically offer considerable clinical, logistical and cost benefits. Despite advances in virtual reality and vision hardware and software, these benefits are currently often unrealised. The proposed approach combines high spatial and temporal resolution 3D and 2D machine vision with virtual reality techniques, in order to develop new environments and instruments that will enable realistic remote consultations and the generation of new types of useful clinical data. New types of clinical data have been generated for skin analysis and respiration measurement; and the combination of 3D with 2D data was found to offer potential for the generation of realistic virtual consultations. An innovative combination of high resolution machine vision data and virtual reality online methods, promises to provide advanced functionality and significant medical benefits, particularly in regions where populations are dispersed or access to clinicians is limited. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  6. HYBRID EXCITATION CLAW-POLE SYNCHRONOUS GENERATOR WITH MAGNETIC CIRCUIT SERIES CONNECTION%串联磁路混合励磁爪极发电机的研究

    Institute of Scientific and Technical Information of China (English)

    赵朝会; 秦海鸿; 严仰光

    2009-01-01

    针对电励磁爪极发电机效率低、永磁爪极发电机磁场调节困难的问题,提出了一种串联磁路混合励磁爪极同步发电机,利用磁路计算方法和三维有限元的分析研究了这种新型电机各部分的磁密大小,确定了合适的极对数和合理的磁钢厚度,探讨了这种新型电机的空载特性、外特性和调节特性.研究表明:串联磁路混合励磁爪极发电机合适的极对数为2,且磁钢厚度存在一个较为合理的优化值.相对于电励磁爪极发电机,它实现了励磁电流的双向控制;相对于永磁爪极发电机它使得输出电压可调,在更宽的负载范围内实现了输出电压的恒定.在参数相同的情况下,与电励磁爪极发电机相比,该电机具有更高的气隙磁密和功率密度.%To solve the low efficiency of electric excitation claw-pole synchronous generator(EECPSG) and regulate the magnetic field of permanent magnet (PM) claw-pole synchronous generator(PMCPSG), a novel hybrid excitation claw-pole synchronous generator(HECPSG) with magnetic circuit series connection is proposed. Through the simulation study on the generator using the calculation method for magnetic circuit and 3-D finite element method(FEA), the appropriate magnet thickness and the number of pole-pairs for the proposed generator are determined. Its off-loading characteristics, load characteristics, and regulation behaviors are investigated. The study shows that the appropriate number of pole-pairs in HECPSG with series magnetic circuits is two, and there exists an optimum magnet thickness.Compared to EECPSG, HECPSG realizes dual-directional control to the excitation current. Moreover, the generator can adjust the output voltage and keep the output voltage stable in a broad load range. Under the condition of same parametes, the motor has higer air-gap flux density and power density.

  7. 计入光伏发电的电力系统分时段随机生产模拟%A Time-Interval Based Probabilistic Production Simulation of Power System With Grid-Connected Photovoltaic Generation

    Institute of Scientific and Technical Information of China (English)

    郭旭阳; 谢开贵; 胡博; 陈涛; 龙虹毓

    2013-01-01

    With increasingly increased photovoltaic (PV) generation capacity, the PV generation plays an increasingly prominent role in planning and operation, reliability and economy of power system. Using auto regression moving average (ARMA) model the illumination radiation intensity of photoillumination is predicted, and combining with output characteristics of PV generation and clustering theory a multi-state stochastic prediction model of PV output is established, in which the influence of PV generation system itself is taken into account. Using equivalent energy function method the time-interval based probabilistic production simulation of power system containing PV generation is performed. The correctness of probabilistic production simulation in accordance with time-interval is verified by EPRI 36-machine system. Based on the proposed method, the influences of grid-connected PV generation on power system are analyzed in the aspects of economy and reliability.%  随着光伏发电并网容量的不断提高,其对电力系统规划运行,以及可靠性、经济性等方面的影响日益突出。利用自回归滑动平均(auto regression moving average,ARMA)模型对光照辐射强度进行预测,结合光伏出力特性和聚类理论建立了光伏出力多状态随机预测模型,并计入光伏系统自身故障的影响,基于等效电量函数法分时段对含有光伏的电力系统进行随机生产模拟。采用EPRI-36测试系统验证了分时段随机生产模拟方法的正确性,并基于此方法分别从经济性、可靠性等层面分析了光伏并网对电力系统的影响。

  8. Super stereoscopy technique for comfortable and realistic 3D displays.

    Science.gov (United States)

    Akşit, Kaan; Niaki, Amir Hossein Ghanbari; Ulusoy, Erdem; Urey, Hakan

    2014-12-15

    Two well-known problems of stereoscopic displays are the accommodation-convergence conflict and the lack of natural blur for defocused objects. We present a new technique that we name Super Stereoscopy (SS3D) to provide a convenient solution to these problems. Regular stereoscopic glasses are replaced by SS3D glasses which deliver at least two parallax images per eye through pinholes equipped with light selective filters. The pinholes generate blur-free retinal images so as to enable correct accommodation, while the delivery of multiple parallax images per eye creates an approximate blur effect for defocused objects. Experiments performed with cameras and human viewers indicate that the technique works as desired. In case two, pinholes equipped with color filters per eye are used; the technique can be used on a regular stereoscopic display by only uploading a new content, without requiring any change in display hardware, driver, or frame rate. Apart from some tolerable loss in display brightness and decrease in natural spatial resolution limit of the eye because of pinholes, the technique is quite promising for comfortable and realistic 3D vision, especially enabling the display of close objects that are not possible to display and comfortably view on regular 3DTV and cinema.

  9. Improved transcranial magnetic stimulation coil design with realistic head modeling

    Science.gov (United States)

    Crowther, Lawrence; Hadimani, Ravi; Jiles, David

    2013-03-01

    We are investigating Transcranial magnetic stimulation (TMS) as a noninvasive technique based on electromagnetic induction which causes stimulation of the neurons in the brain. TMS can be used as a pain-free alternative to conventional electroconvulsive therapy (ECT) which is still widely implemented for treatment of major depression. Development of improved TMS coils capable of stimulating subcortical regions could also allow TMS to replace invasive deep brain stimulation (DBS) which requires surgical implantation of electrodes in the brain. Our new designs allow new applications of the technique to be established for a variety of diagnostic and therapeutic applications of psychiatric disorders and neurological diseases. Calculation of the fields generated inside the head is vital for the use of this method for treatment. In prior work we have implemented a realistic head model, incorporating inhomogeneous tissue structures and electrical conductivities, allowing the site of neuronal activation to be accurately calculated. We will show how we utilize this model in the development of novel TMS coil designs to improve the depth of penetration and localization of stimulation produced by stimulator coils.

  10. Realistic Data-Driven Traffic Flow Animation Using Texture Synthesis.

    Science.gov (United States)

    Chao, Qianwen; Deng, Zhigang; Ren, Jiaping; Ye, Qianqian; Jin, Xiaogang

    2017-01-11

    We present a novel data-driven approach to populate virtual road networks with realistic traffic flows. Specifically, given a limited set of vehicle trajectories as the input samples, our approach first synthesizes a large set of vehicle trajectories. By taking the spatio-temporal information of traffic flows as a 2D texture, the generation of new traffic flows can be formulated as a texture synthesis process, which is solved by minimizing a newly developed traffic texture energy. The synthesized output captures the spatio-temporal dynamics of the input traffic flows, and the vehicle interactions in it strictly follow traffic rules. After that, we position the synthesized vehicle trajectory data to virtual road networks using a cage-based registration scheme, where a few traffic-specific constraints are enforced to maintain each vehicle's original spatial location and synchronize its motion in concert with its neighboring vehicles. Our approach is intuitive to control and scalable to the complexity of virtual road networks. We validated our approach through many experiments and paired comparison user studies.

  11. Modelisation of synchrotron radiation losses in realistic tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Albajar, F.; Johner, J.; Granata, G

    2000-08-01

    Synchrotron radiation losses become significant in the power balance of high-temperature plasmas envisaged for next step tokamaks. Due to the complexity of the exact calculation, these losses are usually roughly estimated with expressions derived from a plasma description using simplifying assumptions on the geometry, radiation absorption, and density and temperature profiles. In the present article, the complete formulation of the transport of synchrotron radiation is performed for realistic conditions of toroidal plasma geometry with elongated cross-section, using an exact method for the calculation of the absorption coefficient, and for arbitrary shapes of density and temperature profiles. The effects of toroidicity and temperature profile on synchrotron radiation losses are analyzed in detail. In particular, when the electron temperature profile is almost flat in the plasma center, as for example in ITB confinement regimes, synchrotron losses are found to be much stronger than in the case where the profile is represented by its best generalized parabolic approximation, though both cases give approximately the same thermal energy contents. Such an effect is not included in present approximate expressions. Finally, we propose a seven-variable fit for the fast calculation of synchrotron radiation losses. This fit is derived from a large database, which has been generated using a code implementing the complete formulation and optimized for massively parallel computing. (author)

  12. Boundary effects in welded steel moment connections

    Science.gov (United States)

    Lee, Kyoung-Hyeog

    Unprecedented widespread failure of welded moment connections in steel frames caused by the 1994 Northridge and the 1995 Kobe earthquakes have alarmed the engineering communities throughout the world. Welded moment connections in steel frames have been traditionally designed by using the classical beam theory which leads to assumptions that the flanges transfer moment while the web connection primarily resists the shear force. However, this study shows that the magnitude and direction of the principal stresses in the connection region are better approximated by using truss analogy rather than the classical beam theory. Accordingly, both the bending moment and the shear force are transferred across the connection near the beam flanges through diagonal strut action. Thus, the beam flange region of the traditionally designed connection is overloaded. This conclusion explains, to a large extent, the recently observed steel moment connection failures. In this study, detailed finite element analyses were carried out for a representative beam-to-column subassemblage with fully welded connection. The stress distribution in the beam web and flanges in the vicinity of the connection were closely studied. The factors responsible for stress redistribution and concentration were identified by using fundamental principles of mechanics. It was concluded that peak resultant stresses can exceed the values used in simple design calculations by large margins. Using the finite element analysis results and the truss analogy to establish a realistic load path in the connection, a practical and more rational analysis and design procedure was developed. The proposed design procedure and the new connection details were successfully validated through cyclic load testing of a nearly full size specimen. The truss model represented the force transmission around the beam-to-column moment connection region very well. Results of the finite element analyses and the laboratory testing showed

  13. Larval dispersal modeling of pearl oyster Pinctada margaritifera following realistic environmental and biological forcing in Ahe atoll lagoon.

    Directory of Open Access Journals (Sweden)

    Yoann Thomas

    Full Text Available Studying the larval dispersal of bottom-dwelling species is necessary to understand their population dynamics and optimize their management. The black-lip pearl oyster (Pinctada margaritifera is cultured extensively to produce black pearls, especially in French Polynesia's atoll lagoons. This aquaculture relies on spat collection, a process that can be optimized by understanding which factors influence larval dispersal. Here, we investigate the sensitivity of P. margaritifera larval dispersal kernel to both physical and biological factors in the lagoon of Ahe atoll. Specifically, using a validated 3D larval dispersal model, the variability of lagoon-scale connectivity is investigated against wind forcing, depth and location of larval release, destination location, vertical swimming behavior and pelagic larval duration (PLD factors. The potential connectivity was spatially weighted according to both the natural and cultivated broodstock densities to provide a realistic view of connectivity. We found that the mean pattern of potential connectivity was driven by the southwest and northeast main barotropic circulation structures, with high retention levels in both. Destination locations, spawning sites and PLD were the main drivers of potential connectivity, explaining respectively 26%, 59% and 5% of the variance. Differences between potential and realistic connectivity showed the significant contribution of the pearl oyster broodstock location to its own dynamics. Realistic connectivity showed larger larval supply in the western destination locations, which are preferentially used by farmers for spat collection. In addition, larval supply in the same sectors was enhanced during summer wind conditions. These results provide new cues to understanding the dynamics of bottom-dwelling populations in atoll lagoons, and show how to take advantage of numerical models for pearl oyster management.

  14. Larval Dispersal Modeling of Pearl Oyster Pinctada margaritifera following Realistic Environmental and Biological Forcing in Ahe Atoll Lagoon

    Science.gov (United States)

    Thomas, Yoann; Dumas, Franck; Andréfouët, Serge

    2014-01-01

    Studying the larval dispersal of bottom-dwelling species is necessary to understand their population dynamics and optimize their management. The black-lip pearl oyster (Pinctada margaritifera) is cultured extensively to produce black pearls, especially in French Polynesia's atoll lagoons. This aquaculture relies on spat collection, a process that can be optimized by understanding which factors influence larval dispersal. Here, we investigate the sensitivity of P. margaritifera larval dispersal kernel to both physical and biological factors in the lagoon of Ahe atoll. Specifically, using a validated 3D larval dispersal model, the variability of lagoon-scale connectivity is investigated against wind forcing, depth and location of larval release, destination location, vertical swimming behavior and pelagic larval duration (PLD) factors. The potential connectivity was spatially weighted according to both the natural and cultivated broodstock densities to provide a realistic view of connectivity. We found that the mean pattern of potential connectivity was driven by the southwest and northeast main barotropic circulation structures, with high retention levels in both. Destination locations, spawning sites and PLD were the main drivers of potential connectivity, explaining respectively 26%, 59% and 5% of the variance. Differences between potential and realistic connectivity showed the significant contribution of the pearl oyster broodstock location to its own dynamics. Realistic connectivity showed larger larval supply in the western destination locations, which are preferentially used by farmers for spat collection. In addition, larval supply in the same sectors was enhanced during summer wind conditions. These results provide new cues to understanding the dynamics of bottom-dwelling populations in atoll lagoons, and show how to take advantage of numerical models for pearl oyster management. PMID:24740288

  15. The use and limitation of realistic evaluation as a tool for evidence-based practice: a critical realist perspective.

    Science.gov (United States)

    Porter, Sam; O'Halloran, Peter

    2012-03-01

    The use and limitation of realistic evaluation as a tool for evidence-based practice: a critical realist perspective In this paper, we assess realistic evaluation's articulation with evidence-based practice (EBP) from the perspective of critical realism. We argue that the adoption by realistic evaluation of a realist causal ontology means that it is better placed to explain complex healthcare interventions than the traditional method used by EBP, the randomized controlled trial (RCT). However, we do not conclude from this that the use of RCTs is without merit, arguing that it is possible to use both methods in combination under the rubric of realist theory. More negatively, we contend that the rejection of critical theory and utopianism by realistic evaluation in favour of the pragmatism of piecemeal social engineering means that it is vulnerable to accusations that it promotes technocratic interpretations of human problems. We conclude that, insofar as realistic evaluation adheres to the ontology of critical realism, it provides a sound contribution to EBP, but insofar as it rejects the critical turn of Bhaskar's realism, it replicates the technocratic tendencies inherent in EBP. © 2011 Blackwell Publishing Ltd.

  16. Smoothing of Grid-connected Wind-Diesel Power Output Using Energy Capacitor System

    Directory of Open Access Journals (Sweden)

    Adel A. Elbaset

    2014-06-01

    Full Text Available This paper presents a small hybrid power system consists of two types of power generation; wind turbine and diesel generation, DG connected to power distribution system. The fluctuations like random nature of wind power, turbulent wind, and sudden changes in load demand create imbalances in power distribution that can affect the frequency and the voltage in the power system. So, addition of Energy capacitor System, ECS is useful for compensation of fluctuating power, since it is capable of controlling both active and reactive power simultaneously and can smooth the output power flow. Hence, this paper proposes herein a dynamic model and simulation of a grid connected wind/DG based-ECS with power flow controllers between load and generation. Moreover, the paper presents a study to analyze the leveling of output fluctuation of wind power with the installation of ECS. To control the power exchanged between the ECS system and the AC grid, a load Following Control, LFC based supervisor is proposed with the aim to minimize variations of the power generated by the diesel generator. The interesting performance of the proposed supervisor is shown with the help of simulations. The computer simulation program is confirmed on a realistic circuit model which implemented in the Simulink environment of Matlab and works as if on line.

  17. Development and validation of a realistic head model for EEG

    Science.gov (United States)

    Bangera, Nitin Bhalchandra

    The utility of extracranial electrical or magnetic field recordings (EEG or MEG) is greatly enhanced if the generators of the bioelectromagnetic fields can be determined accurately from the measured fields. This procedure, known as the 'inverse method,' depends critically on calculations of the projection from generators in the brain to the EEG and MEG sensors. Improving and validating this calculation, known as the 'forward solution,' is the focus of this dissertation. The improvements involve more accurate modeling of the structures of the brain and thus understanding how current flows within the brain as a result of addition of structures in the forward model. Validation compares calculations using different forward models to the experimental results obtained by stimulating with implanted dipole electrodes. The human brain tissue displays inhomogeneity in electrical conductivity and also displays anisotropy, notably in the skull and brain white matter. In this dissertation, a realistic head model has been implemented using the finite element method to calculate the effects of inhomogeneity and anisotropy in the human brain. Accurate segmentation of the brain tissue type is implemented using a semi-automatic method to segment multimodal imaging data from multi-spectral MRI scans (different flip angles) in conjunction with the regular T1-weighted scans and computed x-ray tomography images. The electrical conductivity in the anisotropic white matter tissue is quantified from diffusion tensor MRI. The finite element model is constructed using AMIRA, a commercial segmentation and visualization tool and solved using ABAQUS, a commercial finite element solver. The model is validated using experimental data collected from intracranial stimulation in medically intractable epileptic patients. Depth electrodes are implanted in medically intractable epileptic patients in order to direct surgical therapy when the foci cannot be localized with the scalp EEG. These patients

  18. Simulating Longitudinal Brain MRIs with Known Volume Changes and Realistic Variations in Image Intensity.

    Science.gov (United States)

    Khanal, Bishesh; Ayache, Nicholas; Pennec, Xavier

    2017-01-01

    This paper presents a simulator tool that can simulate large databases of visually realistic longitudinal MRIs with known volume changes. The simulator is based on a previously proposed biophysical model of brain deformation due to atrophy in AD. In this work, we propose a novel way of reproducing realistic intensity variation in longitudinal brain MRIs, which is inspired by an approach used for the generation of synthetic cardiac sequence images. This approach combines a deformation field obtained from the biophysical model with a deformation field obtained by a non-rigid registration of two images. The combined deformation field is then used to simulate a new image with specified atrophy from the first image, but with the intensity characteristics of the second image. This allows to generate the realistic variations present in real longitudinal time-series of images, such as the independence of noise between two acquisitions and the potential presence of variable acquisition artifacts. Various options available in the simulator software are briefly explained in this paper. In addition, the software is released as an open-source repository. The availability of the software allows researchers to produce tailored databases of images with ground truth volume changes; we believe this will help developing more robust brain morphometry tools. Additionally, we believe that the scientific community can also use the software to further experiment with the proposed model, and add more complex models of brain deformation and atrophy generation.

  19. Connectivity of Caribbean coral populations: complementary insights from empirical and modelled gene flow

    NARCIS (Netherlands)

    Foster, N.L.; Paris, C.B.; Kool, J.T.; Baums, I.B.; Stevens, J.R.; Sanchez, J.A.; Bastidas, C.; Agudelo, C.; Bush, P.; Day, O.; Ferrari, R.; Gonzalez, P.; Gore, S.; Guppy, R.; McCartney, M.A.; McCoy, C.; Mendes, J.; Srinivasan, A.; Steiner, S.; Vermeij, M.J.A.; Weil, E.; Mumby, P.J.

    2012-01-01

    Understanding patterns of connectivity among populations of marine organisms is essential for the development of realistic, spatially explicit models of population dynamics. Two approaches, empirical genetic patterns and oceanographic dispersal modelling, have been used to estimate levels of

  20. Using realist synthesis to understand the mechanisms of interprofessional teamwork in health and social care.

    Science.gov (United States)

    Hewitt, Gillian; Sims, Sarah; Harris, Ruth

    2014-11-01

    Realist synthesis offers a novel and innovative way to interrogate the large literature on interprofessional teamwork in health and social care teams. This article introduces realist synthesis and its approach to identifying and testing the underpinning processes (or "mechanisms") that make an intervention work, the contexts that trigger those mechanisms and their subsequent outcomes. A realist synthesis of the evidence on interprofessional teamwork is described. Thirteen mechanisms were identified in the synthesis and findings for one mechanism, called "Support and value" are presented in this paper. The evidence for the other twelve mechanisms ("collaboration and coordination", "pooling of resources", "individual learning", "role blurring", "efficient, open and equitable communication", "tactical communication", "shared responsibility and influence", "team behavioural norms", "shared responsibility and influence", "critically reviewing performance and decisions", "generating and implementing new ideas" and "leadership") are reported in a further three papers in this series. The "support and value" mechanism referred to the ways in which team members supported one another, respected other's skills and abilities and valued each other's contributions. "Support and value" was present in some, but far from all, teams and a number of contexts that explained this variation were identified. The article concludes with a discussion of the challenges and benefits of undertaking this realist synthesis.

  1. Grid-connection device based on TMS320F28027 for photovoltaic power generation%基于TMS320F28027的光伏并网发电装置

    Institute of Scientific and Technical Information of China (English)

    胡小行; 杨景常; 周涛; 敬海兵; 韩冬军

    2012-01-01

    提出了满足光伏并网发电的逆变器和最大功率点跟踪(MPPT)的设计方法.光伏并网发电装置系统的硬件以TMS320F28027为核心处理器,光耦与驱动芯片IR2110为隔离驱动电路,DC-AC为逆变主电路,包括滤波和升压模块、信号采集调理模块;系统软件设计采用SPWM控制策略实现对光伏直流电源的逆变,通过调节SPWM信号的占空比实现MPPT控制策略.装置采用闭环控制,最后给出了系统指标,实现并网同频、同相和逆变效率较高、谐波较少的要求.%The design method of inverter and MPPT(Maximum Power Point Tracking) is proposed for the grid connection device of photovoltaic power generation. Its hardware takes TMS320F28027 as its core processor, IR2110 (optical coupler and driving chip) as its isolated driving circuit, and DC-AC circuit, including the filter & Boost module and the signal acquisition & conditioning module,as its inverter. Its software applies the SPWM control strategy to realize the inversion of photovoltaic DC power and the duty cycle regulation to realize MPPT. The device adopts the closed-loop control and its system indicators are given, which meets the requirements of grid connection for same frequency and phase, higher inverter efficiency and less harmonic.

  2. 直驱风力发电三相并网逆变电源研究%The Research on Three-phase Grid-connected Inverters for Direct-drive Wind Power Generation

    Institute of Scientific and Technical Information of China (English)

    田君龙; 陈荣

    2013-01-01

    The control and algorithm for the space vector pulse width modulation (SVPWM) was analyzed in the three-phase grid-connected inverters for direct-drive wind power generation. Compared with the traditional pulse width modulation, the SVPWM control has the advantages of high DC voltage utilization and low harmonic. Combined with Matlab software simulation system, the vector control method was analyzed. In order to verify the correctness of the control theory, the experimental platform based on high-speed digital processing chip TMS320F2812DSP was designed. The experimental results show that the control scheme is feasible and the grid-connected current could have a good tracking of the voltage change, the system achieves unity power factor to the grid.%以直驱风力发电的三相并网逆变电源为研究对象,针对传统的脉冲宽度调制方式谐波含量高、直流侧电压利用率低等不足,采用空间矢量脉宽调制(SVPWM)的算法控制.利用Matlab软件仿真系统,对该矢量控制方法进行分析.为了进一步验证控制理论的有效性,设计了基于高速数字化处理芯片TMS320F2812DSP的实验平台.实验结果表明该控制方案可行,系统并网效果良好,实现了单位功率因数并网,使电流能够很好的跟踪电网电压的变化.

  3. Design of Power Generating Unit in 30 MW Peak Value Grid-connected Photovoltaic Power Plant%峰值30MW并网光伏电站发电单元设计

    Institute of Scientific and Technical Information of China (English)

    智腾飞; 王金梅; 台流臣; 朱菊; 肖龙

    2012-01-01

    A power generating unit design including the choices of photovoltaic(PV) module and inverter based on the technical parameters of 30 MW peak value grid-connected PV power plant was proposed. Statistics analysis was conducted on solar radiation data of chosing engineering area in the typical year with the assistance of RETScreen, Based on the above analysis, the curve chart was done, which can be concluded that the average daily solar radiation get most in a year when the tilt angle of PV modules is 36? Designed the technical parameters of the LCL filter. The output current and its harmonics through LCL filter were simulated via Mat-lab/Simulink. The result indicates that current waveform has been significantly improved due to the above experiment. Moreover, the harmonics content fulfill the index requirements for current harmonic technique of grid-connected system.%针对峰值30 MW并网光伏电站的技术参数要求,提出发电单元设计方案,包括太阳能电池组件与逆变器选型等,并利用RETScreen软件对所选工程代表年的太阳辐射资料进行数据分析,做出曲线图,得到结论:当太阳能电池组件的倾角为36°时,全年日平均太阳总辐射量最大.设计了LCL滤波器的参数,通过Matlab/Simulink对滤波器输出电流进行仿真并检测谐波含量,电流波形改善明显,输出电流谐波含量符合并网发电系统入网电流的谐波技术指标要求.

  4. The Study on Solid Oxide Fuel Cell with Grid Connected Power Generation%固体氧化物燃料电池及其并网发电研究

    Institute of Scientific and Technical Information of China (English)

    王鹤; 尚学武; 刘博

    2011-01-01

    The Solid Oxide Fuel Cell(SOFC) is a new generating set,which directly changes the chemical energy into electric energy at high temperatures.This paper deals with the modeling and analysis of the model of SOFC system in response to the grid connection.The SOFC is interfaced with Buck-Boost converter to obtain stable DC output voltage;then the three-phase inverter widi constant power control using SPWM technique is connected to ensure stable operation in a microgrid.Several simulations using PSCAD/EMTDC software are implemented to show that SOFC can support stable power output,and that it can provide certain load following capacity under the support of energy storage devices and power electronic equipments.%固体氧化物燃料电池(Solid Oxide Fuel Cell,SOFC)是一种在中高温下直接将燃料中的化学能转化成电能的新型发电装置。对SOFC及其并网发电系统的动态数学模型进行研究,将SOFC与Buck-Boost变换器连接获得稳定的直流输出电压,然后再通过采用SPWM恒功率控制的三相逆变器并网发电。基于PSCAD/EMTDC软件环境的仿真实验证明了SOFC能够在微网中提供稳定的功率输出,并且在储能装置和电力电子设备的支持下,SOFC发电系统能够在一定范围内动态的跟踪负荷的变化。

  5. 并网永磁直驱式风电系统的模态分析%Modal analysis of a grid-connected direct-drive permanent magnet synchronous generator wind turbine system

    Institute of Scientific and Technical Information of China (English)

    谭谨; 王晓茹; 陈哲

    2013-01-01

    为研究永磁直驱风电系统(PMSG)并网后自身的稳定性问题,进行了并网风电系统的模态分析。建立了适用于系统小扰动稳定分析的 PMSG 风电系统模型,研究了并网风机无穷大系统的模式特性。采用特征值法分析了轴系模型、轴系刚性参数、运行点、并网距离对并网风电系统模式的影响。并在PSCAD/EMTDC上建立了相应的非线性模型,利用Prony方法对输出功率曲线进行模式识别,验证了模态分析结论。研究从模态分析的角度说明了轴系双质块建模的重要性,以及上述参数对并网PMSG稳定性影响的相关结论,结果有助于了解并网PMSG风电系统稳定性问题的本质。%In order to study the stability of a grid-connected direct-drive permanent magnet synchronous generator (PMSG) wind turbine systems, this paper presents the modal analysis of a PMSG wind turbine system. A PMSG model suitable for small signal stability analysis is presented. The modal properties of a grid-connected PMSG wind turbine system are studied. Then the comprehensive impacts of the shaft model, shaft parameters, operation points and lengths of the transmission line on the modal characteristic of the system are investigated by the eigenvalue analysis method. Meanwhile, the corresponding nonlinear model is set up in the PSCAD/EMTDC, and the output power curve is analyzed by Prony method to validate the modal analysis results. The results show the importance of shaft two-mass model and the relationship between the stability of PMSG system and the system parameters from the angle of modal analysis. It offers a better understanding about the essence of the stability of grid-connected PMSG wind turbine system. This work is supported by National Natural Science Foundation of China (No. 50937002).

  6. Low Voltage Ride-Through Control of High Power Inverter for Gird-Connection of Photovoltaic Generation%大功率光伏逆变器的低电压穿越控制

    Institute of Scientific and Technical Information of China (English)

    周京华; 刘劲东; 陈亚爱; 李津

    2013-01-01

      根据光伏阵列输出特性和电网电压异常时响应要求,选取抑制负序电流以保持三相并网电流平衡作为控制目标,建立含有LCL网侧滤波器的并网逆变器数学模型,计算精确的电流指令。基于正负序双电流环控制,提出电网电压不平衡时的滤波电容电流前馈有源阻尼控制,并引入电网电压前馈以抑制电压跌落瞬间的电流冲击,结合快速的正负序分量提取和精确的电网电压同步信号,保证了大功率光伏并网系统的稳定并网运行和电网故障时的低电压穿越。仿真及实验结果均验证了控制策略的有效性。%  Based on output characteristics of photovoltaic (PV) array and the requirement for the response of grid-connected PV inverter under abnormal grid voltage, taking maintaining the balance among three-phase grid-connected currents by suppressing negative-sequence current as control objective, a mathematical model containing LCL filter at grid-side is established to calculate accurate current instruction. Based on positive- and negative-sequence dual closed-loop current control, an active feed-forward damping control of filter capacitor current under unbalanced grid voltage is put forward, and the grid voltage feed-forward control is led in to suppress the current impact at the moment of voltage dip;combining with fast extraction of positive- and negative-sequence components of current and accurate synchronization signal of grid voltage, the stable operation of grid-connected high-power inverter for PV generation system and its low voltage ride-through (LVRT) under fault occurred in power grid can be ensured. Both results from simulation and experiments prove that the proposed control strategy is effective.

  7. Realistic Visualization of Virtual Views and Virtual Cinema

    DEFF Research Database (Denmark)

    Livatino, Salvatore

    2005-01-01

    Realistic Virtual View Visualization is a new field of research which has received increasing attention in recent years. It is strictly related to the increased popularity of virtual reality and the spread of its applications, among which virtual photography and cinematography. The use of computer...... is then gaining consensus: the augmented actor. Fundamental concepts and examples of methods proposed for realistic view synthesis, based on the transfer of photorealism from reference photographs to novel views, will be presented. The application of methods for realistic image synthesis to virtual cinematography...

  8. Wind Generators

    Science.gov (United States)

    1989-01-01

    When Enerpro, Inc. president, Frank J. Bourbeau, attempted to file a patent on a system for synchronizing a wind generator to the electric utility grid, he discovered Marshall Space Flight Center's Frank Nola's power factor controller. Bourbeau advanced the technology and received a NASA license and a patent for his Auto Synchronous Controller (ASC). The ASC reduces generator "inrush current," which occurs when large generators are abruptly brought on line. It controls voltage so the generator is smoothly connected to the utility grid when it reaches its synchronous speed, protecting the components from inrush current damage. Generator efficiency is also increased in light winds by applying lower than rated voltage. Wind energy is utilized to drive turbines to generate electricity for utility companies.

  9. Structural Properties of Realistic Cultural Space Distributions

    CERN Document Server

    Babeanu, Alexandru-Ionut; Garlaschelli, Diego

    2015-01-01

    An interesting sociophysical research problem consists of the compatibility between collective social behavior in the short term and cultural diversity in the long term. Recently, it has been shown that, when studying a model of short term collective behavior in parallel with one of long term cultural diversity, one is lead to the puzzling conclusion that the 2 aspects are mutually exclusive. However, the compatibility is restored when switching from the randomly generated cultural space distribution to an empirical one for specifying the initial conditions in those models. This calls for understanding the extent to which such a compatibility restoration is independent of the empirical data set, as well as the relevant structural properties of such data. Firstly, this work shows that the restoration patterns are largely robust across data sets. Secondly, it provides a possible mechanism explaining the restoration, for the special case when the cultural space is formulated only in terms of nominal variables. T...

  10. Realistic Silver Optical Constants for Plasmonics

    Science.gov (United States)

    Jiang, Yajie; Pillai, Supriya; Green, Martin A.

    2016-07-01

    Silver remains the preferred conductor for optical and near-infrared plasmonics. Many high-profile studies focus exclusively on performance simulation in such applications. Almost invariably, these use silver optical data either from Palik’s 1985 handbook or, more frequently, an earlier Johnson and Christy (J&C) tabulation. These data are inconsistent, making it difficult to ascertain the reliability of the simulations. The inconsistency stems from challenges in measuring representative properties of pristine silver, due to tarnishing on air exposure. We demonstrate techniques, including use of silicon-nitride membranes, to access the full capabilities of multiple-angle, spectrometric-ellipsometry to generate an improved data set, representative of overlayer-protected, freshly-deposited silver films on silicon-nitride and glass.

  11. Connectivity of communication networks

    CERN Document Server

    Mao, Guoqiang

    2017-01-01

    This book introduces a number of recent developments on connectivity of communication networks, ranging from connectivity of large static networks and connectivity of highly dynamic networks to connectivity of small to medium sized networks. This book also introduces some applications of connectivity studies in network optimization, in network localization, and in estimating distances between nodes. The book starts with an overview of the fundamental concepts, models, tools, and methodologies used for connectivity studies. The rest of the chapters are divided into four parts: connectivity of large static networks, connectivity of highly dynamic networks, connectivity of small to medium sized networks, and applications of connectivity studies.

  12. A Clustering Graph Generator

    Energy Technology Data Exchange (ETDEWEB)

    Winlaw, Manda [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); De Sterck, Hans [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Sanders, Geoffrey [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-26

    In very simple terms a network can be de ned as a collection of points joined together by lines. Thus, networks can be used to represent connections between entities in a wide variety of elds including engi- neering, science, medicine, and sociology. Many large real-world networks share a surprising number of properties, leading to a strong interest in model development research and techniques for building synthetic networks have been developed, that capture these similarities and replicate real-world graphs. Modeling these real-world networks serves two purposes. First, building models that mimic the patterns and prop- erties of real networks helps to understand the implications of these patterns and helps determine which patterns are important. If we develop a generative process to synthesize real networks we can also examine which growth processes are plausible and which are not. Secondly, high-quality, large-scale network data is often not available, because of economic, legal, technological, or other obstacles [7]. Thus, there are many instances where the systems of interest cannot be represented by a single exemplar network. As one example, consider the eld of cybersecurity, where systems require testing across diverse threat scenarios and validation across diverse network structures. In these cases, where there is no single exemplar network, the systems must instead be modeled as a collection of networks in which the variation among them may be just as important as their common features. By developing processes to build synthetic models, so-called graph generators, we can build synthetic networks that capture both the essential features of a system and realistic variability. Then we can use such synthetic graphs to perform tasks such as simulations, analysis, and decision making. We can also use synthetic graphs to performance test graph analysis algorithms, including clustering algorithms and anomaly detection algorithms.

  13. Spatial organization and connectivity of caves

    Science.gov (United States)

    Jouves, Johan; Viseur, Sophie; Guglielmi, Yves; Camus, Hubert

    2015-04-01

    The main particularity of karst systems is their hierarchical organization as three-dimensional network of conduits behaving as drain. They are recognized as having a major influence on fluid flow at reservoir scale. However, a karstic network is generally hardly continuously observable and their great intrinsic heterogeneity makes their characterization very complex. This media can be only observed by speleological investigation, conditioned to human possibilities. As a result, only few parts can be observed and therefore it is required to model the non-observable parts for reservoir characterizations. To provide realistic 3D models, non-observable karstic features will be generated using parameters extracted from observed ones. Morphometric analysis of the three-dimensional karstic network provides quantitative measures that can (i) give information on speleogenesis processes, (ii) be used to compare different karst systems, (iii) be correlated with hydrogeological behavior and (iii) control the simulation of realistic karst networks. Recent work done on the subject characterize the karstic network as a whole, without genetic a-priori. However, most of observable caves appears to have a polygenic history due to modifications in boundary conditions and some different karst features can be observed in a same cavity. To study the geometrical organization of caves, we propose to analyze 3D speleological topographies for which speleogenetic context is known. This way, it is possible to characterize karst features according to speleogenetic processes. Several morphometric descriptors have been calculated on three-dimensional topographies provided by speleological works. Some parameters describe the existence of preferential direction of karstification and preferential flow paths, other parameters describe the complexity, geometry and connectivity of the three-dimensional karstic networks. Through the study of fifteen different caves, 150km of 3D data have been analyzed

  14. A framework for creating realistic synthetic fluorescence microscopy image sequences

    CSIR Research Space (South Africa)

    Mabaso, M

    2016-02-01

    Full Text Available of the 9th International Joint Conference on Biomedical Engineering Systems and Technologies, Rome, Italy. 21-23 February, 2016 A Framework for Creating Realistic Synthetic Fluorescence Microscopy Image Sequences Matsilele Mabaso1, Daniel Withey1...

  15. Student Work Experience: A Realistic Approach to Merchandising Education.

    Science.gov (United States)

    Horridge, Patricia; And Others

    1980-01-01

    Relevant and realistic experiences are needed to prepare the student for a future career. Addresses the results of a survey of colleges and universities in the United States in regard to their student work experience (SWE) in fashion merchandising. (Author)

  16. Student Work Experience: A Realistic Approach to Merchandising Education.

    Science.gov (United States)

    Horridge, Patricia; And Others

    1980-01-01

    Relevant and realistic experiences are needed to prepare the student for a future career. Addresses the results of a survey of colleges and universities in the United States in regard to their student work experience (SWE) in fashion merchandising. (Author)

  17. Preliminary Study of Realistic Blast Impact on Cultured Brain Slices

    Science.gov (United States)

    2015-04-01

    hippocampal slice samples to better understand blast-induced brain damage. 15. SUBJECT TERMS RDX spheres , organotypic cultures of hippocampus, small...Preliminary Study of Realistic Blast Impact on Cultured Brain Slices by Thuvan Piehler, Rohan Banton, Lars Piehler, Richard Benjamin, Ray...Aberdeen Proving Ground, MD 21005-5066 ARL-TR-7197 April 2015 Preliminary Study of Realistic Blast Impact on Cultured Brain Slices Thuvan

  18. Three-neutron resonance trajectories for realistic interaction models

    CERN Document Server

    Lazauskas, R

    2005-01-01

    Three-neutron resonances are searched using realistic nucleon-nucleon interaction models. Resonance pole trajectories were explored by artificially binding three-neutron and then gradually removing additional interaction. The final pole positions for three-neutron states up to $|J|$=5/2 finish in the fourth energy quadrant with Re(E)$\\leqslant0$ before additional interaction is removed. This study shows that realistic nucleon-nucleon interaction models exclude possible existence of observable three-neutron resonances.

  19. Toward realistic gauge-Higgs grand unification

    Science.gov (United States)

    Furui, Atsushi; Hosotani, Yutaka; Yamatsu, Naoki

    2016-09-01

    The SO(11) gauge-Higgs grand unification in the Randall-Sundrum warped space is presented. The 4D Higgs field is identified as the zero mode of the fifth-dimensional component of the gauge potentials, or as the fluctuation mode of the Aharonov-Bohm phase θ along the fifth dimension. Fermions are introduced in the bulk in the spinor and vector representations of SO(11). SO(11) is broken to SO(4)×SO(6) by the orbifold boundary conditions, which is broken to SU2×U1×SU3 by a brane scalar. Evaluating the effective potential V(θ), we show that the electroweak symmetry is dynamically broken to U1. The quark-lepton masses are generated by the Hosotani mechanism and brane interactions, with which the observed mass spectrum is reproduced. Proton decay is forbidden thanks to the new fermion number conservation. It is pointed out that there appear light exotic fermions. The Higgs boson mass is determined with the quark-lepton masses given; however, it turns out to be smaller than the observed value.

  20. Toward Realistic Gauge-Higgs Grand Unification

    CERN Document Server

    Furui, Atsushi; Yamatsu, Naoki

    2016-01-01

    The $SO(11)$ gauge-Higgs grand unification in the Randall-Sundrum warped space is presented. The 4D Higgs field is identified as the zero mode of the fifth dimensional component of the gauge potentials, or as the fluctuation mode of the Aharonov-Bohm phase $\\theta_H$ along the fifth dimension. Fermions are introduced in the bulk in the spinor and vector representations of $SO(11)$. $SO(11)$ is broken to $SO(4) \\times SO(6)$ by the orbifold boundary conditions, which is broken to $SU(2)_L \\times U(1)_Y \\times SU(3)_C$ by a brane scalar. Evaluating the effective potential $V_{\\rm eff} (\\theta_H)$, we show that the electroweak symmetry is dynamically broken to $U(1)_{\\rm EM}$. The quark-lepton masses are generated by the Hosotani mechanism and brane interactions, with which the observed mass spectrum is reproduced. The proton decay is forbidden thanks to the new fermion number conservation. It is pointed out that there appear light exotic fermions. The Higgs boson mass is determined with the quark-lepton masses ...

  1. Towards a realistic F-theory GUT

    Science.gov (United States)

    Callaghan, James C.; King, Stephen F.; Leontaris, George K.; Ross, Graham G.

    2012-04-01

    We consider semi-local F-theory GUTs arising from a single E 8 point of local enhancement, leading to simple GUT groups based on E 6, SO(10) and SU(5) with SU(3), SU(4) and SU(5) spectral covers, respectively. Assuming the minimal {{Z}_2} monodromy, we determine the homology classes and the associated spectra after flux breaking for each case. Using these results we construct an E 6 based model that demonstrates, for the first time, that it is possible to construct a phenomenologically viable model which leads to the MSSM at low energies. The exotics that result from flux breaking all get a large mass when singlet fields acquire vacuum expectation values driven by D- and F-flatness. Due to the underlying GUT symmetry and the U(1)s descending from E 8, bare baryon- and lepton-number violating terms are forbidden up to and including dimension 5. As a result nucleon decay is naturally suppressed below present bounds. The μ-term is generated by non-perturbative U(1) breaking effects. After including the effect of flux and instanton corrections acceptable quark and charged lepton masses and mixing angles can be obtained. Neutrinos get a mass from the see-saw mechanism through their coupling to singlet neutrinos that acquire large Majorana mass as a result of the monodromy.

  2. 光伏并网式家用空调系统性能的实验研究%Experimental Investigation on the Performance of Household Air Conditioning System with Grid-connected Photovoltaic Generation

    Institute of Scientific and Technical Information of China (English)

    金听祥; 徐笑锋

    2015-01-01

    With the base of traditional air conditioning system, the grid-connected photovoltaic household air conditioning sys-tem based on the solar photovoltaic power generation technology is designed in this paper. The power with the solar photovoltaic power generation technology is transformed into the household power of 220 V and 50 Hz by inverter. The household air condi-tioning system is then driven by the transformed power and national grid. The performance of the photovoltaic grid-connected household air conditioning system was tested by Enthalpy Difference Lab under the different power ( 100 W, 135 W and 185 W) of solar panels. The experimental results show that under normal cooling conditions, the average power consumption of the air conditioning system with the different power (100 W, 135 W and 185 W) of solar panels are 52 W, 78 W and 104 W lower than that of the traditional air conditioning system respectively. Similarly, energy efficiency ratios of the air conditioning system with the different power (100 W, 135 W and 185 W) of solar panels are 4. 2%, 5. 5% and 10. 2% lower than that of the tra-ditional air conditioning system respectively. Under heating mode, the average power consumption of the air conditioning system with the different power (100 W, 135 W and 185 W) of solar panels are 68 W, 84 W and 116 W lower than that of the tradi-tional air conditioning system, and the coefficients of performances are 6. 4%, 8% and 11% lower than that of the traditional air conditioning system. It can be concluded that the photovoltaic grid-connected household air conditioning system is feasible.%针对目前的家用空调系统,本文设计了一种以太阳能光伏发电技术为基础,与国家电网并网,共同驱动空调工作的系统,称为光伏并网式家用空调系统。利用光伏发电技术,通过逆变器将太阳能提供的电力转变为220 V、50 Hz家用电源,实现与市电电网的并网,来共同驱动空调运行。利用焓差实验室,

  3. Connection Strings Property on ADO Connection Object

    Institute of Scientific and Technical Information of China (English)

    Girigi Deogratias; Wu Min; Cao Weihua

    2002-01-01

    The connection string property on ADO connection object contains the information used to establish a connection to the data source. The syntax, the keyword of that information must be in specific format. Depending on the type of data you are connecting to, you need either specify an OLEDB provider or use on ODBC driver. The biggest problem, the industries face is the proliferation of data access interfaces, and the complexity of creating,maintaining and programming against them, and the network problem when communicating over the Intranet or the Internet. This paper first provides an in-depth look of the standard arguments supported by ADO connection string; then gives the easier way for understanding the meaning, the utility and the syntax of the connection strings property on ADO connection object, and finally proposes solution to work around the problems due to the connection strings errors.

  4. Controlling IP Falsifying Using Realistic Simulation

    Directory of Open Access Journals (Sweden)

    Govindavaram Madhusri

    2013-07-01

    Full Text Available The study of Internet-scale events such as worm proliferation, distributed denial-of-service attacks (DDoS,flash crowds, routing volatilities, and DNS attacks depend on the formation of all the networks thatgenerate or forward valid and malevolent traffic,The Distributed Denial of Services (DDoS attack is aserious threat to the valid use of the Internet. Forestalling mechanisms are disappointed by the ability ofattackers to steal, or spoof, the source addresses in IP packets. IP falsifying is still widespread in networkscanning and investigates, as well as denial of service floods.IDPFs can limit the falsifying capability ofattackers. Moreover, it works on a small number of candidate networks easily traceable, thus simplifyingthe reactive IP trace back process. However, this technique does not allow large number of networks,which is a common misapprehension for those unfamiliar with the practice. Current network simulatorscannot be used to study Internet-scale events. They are general-purpose, packet-level simulators thatreproduce too many details of network communication, which limits scalability. We propose to develop adistributed Internet simulator, with the following novel features. It will provide a built-in Internet model,including the topology, routing, link bandwidths and delays, Instead of being a general-purpose simulator,it will provide a common simulation core for traffic generation and message passing, on top of which wewill build separate modules that customize messages and level of simulation details for the event of interest.Customization modules will ensure that all and only the relevant details of the event of interest aresimulated, cutting down the simulation time. We will also provide an interface for new modulespecification, and for existing module modification, this will bring the Internet event simulation at thefingertips of all interested researchers. The simulator will promote research in worm detection and defense

  5. Multimodal person authentication on a smartphone under realistic conditions

    Science.gov (United States)

    Morris, Andrew C.; Jassim, Sabah; Sellahewa, Harin; Allano, Lorene; Ehlers, Johan; Wu, Dalei; Koreman, Jacques; Garcia-Salicetti, Sonia; Ly-Van, Bao; Dorizzi, Bernadette

    2006-05-01

    Verification of a person's identity by the combination of more than one biometric trait strongly increases the robustness of person authentication in real applications. This is particularly the case in applications involving signals of degraded quality, as for person authentication on mobile platforms. The context of mobility generates degradations of input signals due to the variety of environments encountered (ambient noise, lighting variations, etc.), while the sensors' lower quality further contributes to decrease in system performance. Our aim in this work is to combine traits from the three biometric modalities of speech, face and handwritten signature in a concrete application, performing non intrusive biometric verification on a personal mobile device (smartphone/PDA). Most available biometric databases have been acquired in more or less controlled environments, which makes it difficult to predict performance in a real application. Our experiments are performed on a database acquired on a PDA as part of the SecurePhone project (IST-2002-506883 project "Secure Contracts Signed by Mobile Phone"). This database contains 60 virtual subjects balanced in gender and age. Virtual subjects are obtained by coupling audio-visual signals from real English speaking subjects with signatures from other subjects captured on the touch screen of the PDA. Video data for the PDA database was recorded in 2 recording sessions separated by at least one week. Each session comprises 4 acquisition conditions: 2 indoor and 2 outdoor recordings (with in each case, a good and a degraded quality recording). Handwritten signatures were captured in one session in realistic conditions. Different scenarios of matching between training and test conditions are tested to measure the resistance of various fusion systems to different types of variability and different amounts of enrolment data.

  6. MOHCS: Towards Mining Overlapping Highly Connected Subgraphs

    CERN Document Server

    Lin, Xiahong; Chen, Kefei; Chiu, David K Y

    2008-01-01

    Many networks in real-life typically contain parts in which some nodes are more highly connected to each other than the other nodes of the network. The collection of such nodes are usually called clusters, communities, cohesive groups or modules. In graph terminology, it is called highly connected graph. In this paper, we first prove some properties related to highly connected graph. Based on these properties, we then redefine the highly connected subgraph which results in an algorithm that determines whether a given graph is highly connected in linear time. Then we present a computationally efficient algorithm, called MOHCS, for mining overlapping highly connected subgraphs. We have evaluated experimentally the performance of MOHCS using real and synthetic data sets from computer-generated graph and yeast protein network. Our results show that MOHCS is effective and reliable in finding overlapping highly connected subgraphs. Keywords-component; Highly connected subgraph, clustering algorithms, minimum cut, m...

  7. Minimum cost connection networks

    DEFF Research Database (Denmark)

    Hougaard, Jens Leth; Tvede, Mich

    In the present paper we consider the allocation of cost in connection networks. Agents have connection demands in form of pairs of locations they want to be connected. Connections between locations are costly to build. The problem is to allocate costs of networks satisfying all connection demands...

  8. Numerical Modeling of Plasmonic Nanoantennas with Realistic 3D Roughness and Distortion

    Directory of Open Access Journals (Sweden)

    Vladimir P. Drachev

    2011-07-01

    Full Text Available Nanostructured plasmonic metamaterials, including optical nanoantenna arrays, are important for advanced optical sensing and imaging applications including surface-enhanced fluorescence, chemiluminescence, and Raman scattering. Although designs typically use ideally smooth geometries, realistic nanoantennas have nonzero roughness, which typically results in a modified enhancement factor that should be involved in their design. Herein we aim to treat roughness by introducing a realistic roughened geometry into the finite element (FE model. Even if the roughness does not result in significant loss, it does result in a spectral shift and inhomogeneous broadening of the resonance, which could be critical when fitting the FE simulations of plasmonic nanoantennas to experiments. Moreover, the proposed approach could be applied to any model, whether mechanical, acoustic, electromagnetic, thermal, etc, in order to simulate a given roughness-generated physical phenomenon.

  9. A realistic polarizing Sagnac topology with DC readout for the Einstein Telescope

    CERN Document Server

    Wang, Mengyao; Brown, Daniel; Brueckner, Frank; Carbone, Ludovico; Palmer, Rebecca; Freise, Andreas

    2013-01-01

    The Einstein Telescope (ET) is a proposed future gravitational wave detector. Its design is original, using a triangular orientation of three detectors and a xylophone configuration, splitting each detector into one high-frequency and one low-frequency system. In other aspects the current design retains the dual-recycled Michelson interferometer typical of current detectors, such as Advanced LIGO. In this paper, we investigate the feasibility of replacing the low-frequency part of the ET detectors with a Sagnac interferometer. We show that a Sagnac interferometer, using realistic optical parameters based on the ET design, could provide a similar level of radiation pressure noise suppression without the need for a signal recycling mirror and the extensive filter cavities. We consider the practical issues of a realistic, power-recycled Sagnac, using linear arm cavities and polarizing optics. In particular we investigate the effects of non-perfect polarizing optics and propose a new method for the generation of ...

  10. A realistic theory of health sector management. The case for critical realism.

    Science.gov (United States)

    Connelly, J

    2000-01-01

    To date the practice of health sector management has not been sufficiently theorised. An adequate theory should be able to answer the pre-eminent critique of managerial rationality and ethics mounted by Alasdair MacIntyre in After Virtue and should also offer robust analytical and ethical resources to identify and engage with the social, political, economic and moral issues underlying health sector management. Critical realism with its ontology of generative mechanisms, agency-structure relationships, valorisation of activity and ideology critique offers such resources in an empirically orientated but adequately theorised realist framework. Rather than negate MacIntyre, critical realism incorporates and transcends his key arguments regarding the rationality and ethics of management. This article introduces the main elements of critical realism and clears a conceptual space for the cumulation of critical realist case-studies and managerial craft knowledge.

  11. Attribute-space connectivity and connected filters

    NARCIS (Netherlands)

    Wilkinson, Michael H.F.

    2007-01-01

    In this paper connected operators from mathematical morphology are extended to a wider class of operators, which are based on connectivities in higher dimensional spaces, similar to scale spaces, which will be called attribute-spaces. Though some properties of connected filters are lost, granulometr

  12. Undifferentiated Connective Tissue Disease

    Science.gov (United States)

    ... Home Conditions Undifferentiated Connective Tissue Disease (UCTD) Undifferentiated Connective Tissue Disease (UCTD) Make an Appointment Find a Doctor ... L. Goldstein, MD, MMSc (February 01, 2016) Undifferentiated connective tissue disease (UCTD) is a systemic autoimmune disease. This ...

  13. Connective Tissue Disorders

    Science.gov (United States)

    Connective tissue is the material inside your body that supports many of its parts. It is the "cellular ... their work. Cartilage and fat are examples of connective tissue. There are over 200 disorders that impact connective ...

  14. Minimum cost connection networks

    DEFF Research Database (Denmark)

    Hougaard, Jens Leth; Tvede, Mich

    . We use three axioms to characterize allocation rules that truthfully implement cost minimizing networks satisfying all connection demands in a game where: (1) a central planner announces an allocation rule and a cost estimation rule; (2) every agent reports her own connection demand as well as all...... connection costs; and, (3) the central planner selects a cost minimizing network satisfying reported connection demands based on estimated connection costs and allocates true connection costs of the selected network....

  15. The construction of context-mechanisms-outcomes in realistic evaluation.

    Science.gov (United States)

    Linsley, Paul; Howard, David; Owen, Sara

    2015-01-01

    To discuss the construction of context-mechanisms-outcomes (CMOs) developed as part of a realistic evaluation study of two aggression management training programmes. Realistic evaluation draws on theories and methods derived from the social sciences. It provides a distinctive account of the nature of programmes and how they work. Realistic evaluation is a form of evaluation that is driven by theory, and was based by Pawson and Tilley ( 1997 ) on the philosophy of critical realism. Critical realism is an important perspective in modern philosophy and social science, but it is largely absent in the field of healthcare research. This paper provides a critical discussion on the construction of CMOs as part of a realistic evaluation study. This paper draws on the personal experiences of the author in using realistic evaluation to evaluate training in aggression management. Realistic evaluation stresses four key linked concepts for explaining and understanding programmes: 'mechanism', 'context', 'outcome pattern' and 'context-mechanisms-outcomes (CMO) pattern configuration'. A CMO configuration is a proposition stating what it is about an initiative that works, for whom and in what circumstances. In this way, the effectiveness of the programme is understood, with an explanation of why the outcomes developed as they did and how the programme was able to react to underlying mechanisms and in what contexts. Therefore, a realistic evaluation researcher is not just inspecting outcomes to see if an initiative (implementation) works, but is analysing the outcomes to discover if the conjectured mechanism or context theories are confirmed. This analysis provides not only evidence of effectiveness, but also an explanation that helps to develop and improve the content and the targeting of future programmes. The development of CMOs requires a great deal of skill on the part of the researcher and requires a flexibility of approach when collecting and analysing the data and in

  16. Strengthening connections: functional connectivity and brain plasticity.

    Science.gov (United States)

    Kelly, Clare; Castellanos, F Xavier

    2014-03-01

    The ascendancy of functional neuroimaging has facilitated the addition of network-based approaches to the neuropsychologist's toolbox for evaluating the sequelae of brain insult. In particular, intrinsic functional connectivity (iFC) mapping of resting state fMRI (R-fMRI) data constitutes an ideal approach to measuring macro-scale networks in the human brain. Beyond the value of iFC mapping for charting how the functional topography of the brain is altered by insult and injury, iFC analyses can provide insights into experience-dependent plasticity at the macro level of large-scale functional networks. Such insights are foundational to the design of training and remediation interventions that will best facilitate recovery of function. In this review, we consider what is currently known about the origin and function of iFC in the brain, and how this knowledge is informative in neuropsychological settings. We then summarize studies that have examined experience-driven plasticity of iFC in healthy control participants, and frame these findings in terms of a schema that may aid in the interpretation of results and the generation of hypotheses for rehabilitative studies. Finally, we outline some caveats to the R-fMRI approach, as well as some current developments that are likely to bolster the utility of the iFC paradigm for neuropsychology.

  17. 并网风光发电中混合储能系统容量优化配置%Capacity Optimization of Hybrid Energy Storage System in Grid-Connected Wind and PV Power Generation System

    Institute of Scientific and Technical Information of China (English)

    杨珺; 张建成; 桂勋

    2013-01-01

      提高并网风光发电系统的调度灵活性需要引入储能技术,而储能技术研究的首要关键技术问题就是储能系统的容量配置。利用蓄电池和超级电容器的互补特性,提出了一种以优化蓄电池工作状态为原则,以提高储能系统整体经济性为目标的能量管理策略。基于该能量管理策略分析了并网风光发电系统能量损失率和能量缺失率的计算流程,根据全生命周期费用理论,建立了储能装置的年均费用函数表达式,并建立了以该函数值最小为目标,以系统能量损失率及能量缺失率等运行指标为约束的储能容量优化配置模型。运用改进混沌优化算法对实例进行了计算,验证了该优化模型与算法的正确性和有效性。%  To improve scheduling flexibility of grid-connected Wind and PV power generation system, it is necessary for the system to apply energy storage technology, and the primary key technological problem to be researched is how to determine the capacity configuration of the energy storage system. Using complementary characteristics of the battery and the supercapacitor, an energy management strategy, in which the optimization of battery operating condition is taken as the principle and the improvement of overall economy of energy storage system as the objective, is proposed. Based on the proposed energy management storage, the energy loss rate of grid-connected wind and PV generation system and the calculation course of the rate are analyzed. According to the theory of life cycle cost, the expressions for annual average cost function of energy storage system is established;taking the minimization of this function value as the objective and the loss of produced power probability and the loss of power supply probability as constraints, an optimal configuration model for optimal configuration of the capacity of energy storage system is built. Case calculation is performed by

  18. 下一代互联网中移动自组网的移动管理研究%Mobility management for MANETs connected to next-generation Internet

    Institute of Scientific and Technical Information of China (English)

    王晓喃; 钱焕延

    2012-01-01

    This paper presented a mobility management scheme for MANETs connected to the next-generation Internet. In this scheme,it proposed the MANET hierarchical architecture based on clusters which was fully compatible with the IPv6 network architecture. Accordingly, it proposed the establishment algorithm for establishing a cluster to minimize the number of the cluster heads. Based on the proposed MANET hierarchical architecture, it also put forward the hierarchical IPv6 address structure for MANETs and discussed the corresponding IPv6 address configuration algorithm. Based on the proposed MANET hierarchical architecture and the proposed IPv6 address structure, it presented the mobility management scheme. The comparative results show that the proposed scheme can effectively reduce the number of mobility handovers, and decrease both the control message cost and the packet loss rate.%提出了一种下一代互联网中移动自组网的移动管理方案.此方案提出了与IPv6网络体系结构充分融合的基于簇的MANET层次体系结构,并提出了簇的建立算法,实现了簇首节点数量最小化.基于所提的MANET层次体系结构,提出了MANET节点的IPv6地址分层结构以及相应的IPv6地址配置算法.基于所提的MANET层次体系结构以及IPv6地址分层结构,提出了移动自组网移动管理方案.分析结果验证了本方案有效减少了移动转交次数,降低了控制信息代价以及数据包丢失率.

  19. Breaking with fun, educational and realistic learning games

    DEFF Research Database (Denmark)

    Duus Henriksen, Thomas

    2009-01-01

    between the game and other didactic activities that formed the learning process; and, the game might have been intended to be realistic, but it was in the gaps where this realism was critically assessed that learned understanding was forged. While thinking learning games as fun, educative and realistic......This paper addresses the game conceptions and values that learning games inherit from regular gaming, as well as how they affect the use and development of learning games. Its key points concern the issues of thinking learning games as fun, educative and realistic, which is how learning games...... are commonly conceived as means for staging learning processes, and that thinking learning games so has an inhibiting effect in regard to creating learning processes. The paper draws upon a qualitative study of participants' experiences with ‘the EIS Simulation', which is a computer-based learning game...

  20. Principles of maximally classical and maximally realistic quantum mechanics

    Indian Academy of Sciences (India)

    S M Roy

    2002-08-01

    Recently Auberson, Mahoux, Roy and Singh have proved a long standing conjecture of Roy and Singh: In 2-dimensional phase space, a maximally realistic quantum mechanics can have quantum probabilities of no more than + 1 complete commuting cets (CCS) of observables coexisting as marginals of one positive phase space density. Here I formulate a stationary principle which gives a nonperturbative definition of a maximally classical as well as maximally realistic phase space density. I show that the maximally classical trajectories are in fact exactly classical in the simple examples of coherent states and bound states of an oscillator and Gaussian free particle states. In contrast, it is known that the de Broglie–Bohm realistic theory gives highly nonclassical trajectories.

  1. 2 types of spicules "observed" in 3D realistic models

    CERN Document Server

    Martínez-Sykora, Juan

    2010-01-01

    Realistic numerical 3D models of the outer solar atmosphere show two different kind of spicule-like phenomena, as also observed on the solar limb. The numerical models are calculated using the 2 types of spicules "observed" in 3D realistic models Oslo Staggered Code (OSC) to solve the full MHD equations with non-grey and NLTE radiative transfer and thermal conduction along the magnetic field lines. The two types of spicules arise as a natural result of the dynamical evolution in the models. We discuss the different properties of these two types of spicules, their differences from observed spicules and what needs to be improved in the models.

  2. Putting a Realistic Theory of Mind into Agency Theory

    DEFF Research Database (Denmark)

    Foss, Nicolai Juul; Stea, Diego

    2014-01-01

    concerning other such content. More realistically, individuals have some limited access to the minds of others. We explore the implications for classical agency theory of realistic assumptions regarding the human potential for interpersonal sensemaking. We discuss implications for the design and management......Agency theory is one of the most important foundational theories in management research, but it rests on contestable cognitive assumptions. Specifically, the principal is assumed to hold a perfect (correct) theory regarding some of the content of the agent's mind, while he is entirely ignorant...... of rewards, and trace implications for value creation in principal-agent relations....

  3. The effects of realistic pancake solenoids on particle transport

    Energy Technology Data Exchange (ETDEWEB)

    Gu, X.; Okamura, M.; Pikin, A.; Fischer, W.; Luo, Y.

    2011-02-01

    Solenoids are widely used to transport or focus particle beams. Usually, they are assumed as being ideal solenoids with a high axial-symmetry magnetic field. Using the Vector Field Opera program, we modeled asymmetrical solenoids with realistic geometry defects, caused by finite conductor and current jumpers. Their multipole magnetic components were analyzed with the Fourier fit method; we present some possible optimized methods for them. We also discuss the effects of 'realistic' solenoids on low energy particle transport. The finding in this paper may be applicable to some lower energy particle transport system design.

  4. Evaluating Adverse Effects of Inhaled Nanoparticles by Realistic In Vitro Technology.

    Science.gov (United States)

    Geiser, Marianne; Jeannet, Natalie; Fierz, Martin; Burtscher, Heinz

    2017-02-22

    The number of daily products containing nanoparticles (NP) is rapidly increasing. NP in powders, dispersions, or sprays are a yet unknown risk for incidental exposure, especially at workplaces during NP production and processing, and for consumers of any health status and age using NP containing sprays. We developed the nano aerosol chamber for in vitro toxicity (NACIVT), a portable instrument for realistic safety testing of inhaled NP in vitro and evaluated effects of silver (Ag) and carbon (C) NP-which belong to the most widely used nanomaterials-on normal and compromised airway epithelia. We review the development, physical performance, and suitability of NACIVT for short and long-term exposures with air-liquid interface (ALI) cell cultures in regard to the prerequisites of a realistic in vitro test system for inhalation toxicology and in comparison to other commercially available, well characterized systems. We also review doses applied to cell cultures in vitro and acknowledge that a single exposure to realistic doses of spark generated 20-nm Ag- or CNP results in small, similar cellular responses to both NP types and that cytokine release generally increased with increasing NP dose.

  5. Protocol: realist synthesis of the impact of unemployment insurance policies on poverty and health.

    Science.gov (United States)

    Molnar, Agnes; O'Campo, Patricia; Ng, Edwin; Mitchell, Christiane; Muntaner, Carles; Renahy, Emilie; St John, Alexander; Shankardass, Ketan

    2015-02-01

    Unemployment insurance is an important social protection policy that buffers unemployed workers against poverty and poor health. Most unemployment insurance studies focus on whether increases in unemployment insurance generosity are predictive of poverty and health outcomes. Less work has used theory-driven approaches to understand and explain how and why unemployment insurance works, for whom, and under what circumstances. Given this, we present a realist synthesis protocol that seeks to unpack how contextual influences trigger relevant mechanisms to generate poverty and health outcomes. In this protocol, we conceptualize unemployment insurance as a key social protection policy; provide a supporting rationale on the need for a realist synthesis; and describe our process on identifying context-mechanism-outcome pattern configurations. Six methodological steps are described: initial theory development, search strategy; selection and appraisal of documents; data extraction; analysis and synthesis process; and presentation and dissemination of revised theory. Our forthcoming realist synthesis will be the first to build and test theory on the intended and unintended outcomes of unemployment insurance policies. Anticipated findings will allow policymakers to move beyond 'black box' approaches to consider 'mechanism-based' explanations that explicate the logic on how and why unemployment insurance matters.

  6. Evaluating Adverse Effects of Inhaled Nanoparticles by Realistic In Vitro Technology

    Science.gov (United States)

    Geiser, Marianne; Jeannet, Natalie; Fierz, Martin; Burtscher, Heinz

    2017-01-01

    The number of daily products containing nanoparticles (NP) is rapidly increasing. NP in powders, dispersions, or sprays are a yet unknown risk for incidental exposure, especially at workplaces during NP production and processing, and for consumers of any health status and age using NP containing sprays. We developed the nano aerosol chamber for in vitro toxicity (NACIVT), a portable instrument for realistic safety testing of inhaled NP in vitro and evaluated effects of silver (Ag) and carbon (C) NP—which belong to the most widely used nanomaterials—on normal and compromised airway epithelia. We review the development, physical performance, and suitability of NACIVT for short and long-term exposures with air-liquid interface (ALI) cell cultures in regard to the prerequisites of a realistic in vitro test system for inhalation toxicology and in comparison to other commercially available, well characterized systems. We also review doses applied to cell cultures in vitro and acknowledge that a single exposure to realistic doses of spark generated 20-nm Ag- or CNP results in small, similar cellular responses to both NP types and that cytokine release generally increased with increasing NP dose. PMID:28336883

  7. Hematopoietic stem cell origin of connective tissues.

    Science.gov (United States)

    Ogawa, Makio; Larue, Amanda C; Watson, Patricia M; Watson, Dennis K

    2010-07-01

    Connective tissue consists of "connective tissue proper," which is further divided into loose and dense (fibrous) connective tissues and "specialized connective tissues." Specialized connective tissues consist of blood, adipose tissue, cartilage, and bone. In both loose and dense connective tissues, the principal cellular element is fibroblasts. It has been generally believed that all cellular elements of connective tissue, including fibroblasts, adipocytes, chondrocytes, and bone cells, are generated solely by mesenchymal stem cells. Recently, a number of studies, including those from our laboratory based on transplantation of single hematopoietic stem cells, strongly suggested a hematopoietic stem cell origin of these adult mesenchymal tissues. This review summarizes the experimental evidence for this new paradigm and discusses its translational implications.

  8. Ion size effects on the electric double layer of a spherical particle in a realistic salt-free concentrated suspension.

    Science.gov (United States)

    Roa, Rafael; Carrique, Félix; Ruiz-Reina, Emilio

    2011-05-28

    A new modified Poisson-Boltzmann equation accounting for the finite size of the ions valid for realistic salt-free concentrated suspensions has been derived, extending the formalism developed for pure salt-free suspensions [Roa et al., Phys. Chem. Chem. Phys., 2011, 13, 3960-3968] to real experimental conditions. These realistic suspensions include water dissociation ions and those generated by atmospheric carbon dioxide contamination, in addition to the added counterions released by the particles to the solution. The electric potential at the particle surface will be calculated for different ion sizes and compared with classical Poisson-Boltzmann predictions for point-like ions, as a function of particle charge and volume fraction. The realistic predictions turn out to be essential to achieve a closer picture of real salt-free suspensions, and even more important when ionic size effects are incorporated to the electric double layer description. We think that both corrections have to be taken into account when developing new realistic electrokinetic models, and surely will help in the comparison with experiments for low-salt or realistic salt-free systems. This journal is © the Owner Societies 2011

  9. Countering oversegmentation in partitioning-based connectivities

    NARCIS (Netherlands)

    Ouzounis, Georgios K.; Wilkinson, Michael H.F.

    2005-01-01

    A new theoretical development is presented for handling the over-segmentation problem in partitioning-based connected openings. The definition we propose treats singletons generated with the earlier method, as elements of a larger connected component. Unlike the existing formalism, this new method a

  10. Boundary conditions towards realistic simulation of jet engine noise

    Science.gov (United States)

    Dhamankar, Nitin S.

    Strict noise regulations at major airports and increasing environmental concerns have made prediction and attenuation of jet noise an active research topic. Large eddy simulation coupled with computational aeroacoustics has the potential to be a significant research tool for this problem. With the emergence of petascale computer clusters, it is now computationally feasible to include the nozzle geometry in jet noise simulations. In high Reynolds number experiments on jet noise, the turbulent boundary layer on the inner surface of the nozzle separates into a turbulent free shear layer. Inclusion of a nozzle with turbulent inlet conditions is necessary to simulate this phenomenon realistically. This will allow a reasonable comparison of numerically computed noise levels with the experimental results. Two viscous wall boundary conditions are implemented for modeling the nozzle walls. A characteristic-based approach is compared with a computationally cheaper, extrapolation-based formulation. In viscous flow over a circular cylinder under two different regimes, excellent agreement is observed between the results of the two approaches. The results agree reasonably well with reference experimental and numerical results. Both the boundary conditions are thus found to be appropriate, the extrapolation-based formulation having an edge with its low cost. This is followed with the crucial step of generation of a turbulent boundary layer inside the nozzle. A digital filter-based turbulent inflow condition, extended in a new way to non-uniform curvilinear grids is implemented to achieve this. A zero pressure gradient flat plate turbulent boundary layer is simulated at a high Reynolds number to show that the method is capable of producing sustained turbulence. The length of the adjustment region necessary for synthetic inlet turbulence to recover from modeling errors is estimated. A low Reynolds number jet simulation including a round nozzle geometry is performed and the method

  11. Visualizing neuronal network connectivity with connectivity pattern tables

    Directory of Open Access Journals (Sweden)

    Eilen Nordlie

    2010-01-01

    Full Text Available Complex ideas are best conveyed through well-designed illustrations. Up to now, computational neuroscientists have mostly relied on box-and-arrow diagrams of even complex neuronal networks, often using ad hoc notations with conflicting use of symbols from paper to paper. This significantly impedes the communication of ideas in neuronal network modeling. We present here Connectivity Pattern Tables (CPTs as a clutter-free visualization of connectivity in large neuronal networks containing two-dimensional populations of neurons. CPTs can be generated automatically from the same script code used to create the actual network in the NEST simulator. Through aggregation, CPTs can be viewed at different levels, providing either full detail or summary information. We also provide the open source ConnPlotter tool as a means to create connectivity pattern tables.

  12. On Connectivity of Wireless Sensor Networks with Directional Antennas.

    Science.gov (United States)

    Wang, Qiu; Dai, Hong-Ning; Zheng, Zibin; Imran, Muhammad; Vasilakos, Athanasios V

    2017-01-12

    In this paper, we investigate the network connectivity of wireless sensor networks with directional antennas. In particular, we establish a general framework to analyze the network connectivity while considering various antenna models and the channel randomness. Since existing directional antenna models have their pros and cons in the accuracy of reflecting realistic antennas and the computational complexity, we propose a new analytical directional antenna model called the iris model to balance the accuracy against the complexity. We conduct extensive simulations to evaluate the analytical framework. Our results show that our proposed analytical model on the network connectivity is accurate, and our iris antenna model can provide a better approximation to realistic directional antennas than other existing antenna models.

  13. On Connectivity of Wireless Sensor Networks with Directional Antennas

    Science.gov (United States)

    Wang, Qiu; Dai, Hong-Ning; Zheng, Zibin; Imran, Muhammad; Vasilakos, Athanasios V.

    2017-01-01

    In this paper, we investigate the network connectivity of wireless sensor networks with directional antennas. In particular, we establish a general framework to analyze the network connectivity while considering various antenna models and the channel randomness. Since existing directional antenna models have their pros and cons in the accuracy of reflecting realistic antennas and the computational complexity, we propose a new analytical directional antenna model called the iris model to balance the accuracy against the complexity. We conduct extensive simulations to evaluate the analytical framework. Our results show that our proposed analytical model on the network connectivity is accurate, and our iris antenna model can provide a better approximation to realistic directional antennas than other existing antenna models. PMID:28085081

  14. On Connectivity of Wireless Sensor Networks with Directional Antennas

    Directory of Open Access Journals (Sweden)

    Qiu Wang

    2017-01-01

    Full Text Available In this paper, we investigate the network connectivity of wireless sensor networks with directional antennas. In particular, we establish a general framework to analyze the network connectivity while considering various antenna models and the channel randomness. Since existing directional antenna models have their pros and cons in the accuracy of reflecting realistic antennas and the computational complexity, we propose a new analytical directional antenna model called the iris model to balance the accuracy against the complexity. We conduct extensive simulations to evaluate the analytical framework. Our results show that our proposed analytical model on the network connectivity is accurate, and our iris antenna model can provide a better approximation to realistic directional antennas than other existing antenna models.

  15. 直流逆变分布式电源降阶模型及小扰动稳定分析∗%The Small Signal Stability Analysis of the Grid Connected DC Distributed Generation with Reduced Order Model

    Institute of Scientific and Technical Information of China (English)

    李培强; 胡泽; 李欣然; 周丽英; 曾小军; 邱时严

    2016-01-01

    Compared with the traditional power,many different kinds of micro sources and control modes are used in distributed generation (DG),which makes the small signal electromechanical transient analysis of the power grid difficult.This study established a reduced order model of photovoltaic (PV)power generation considering the behavior of battery and inverter,and presented a power source model of solid-oxide fuel cell (SOFC)by analyzing the charac-teristic patterns of the full-order state-space model and the time constant of SOFC and PV.Then,the model was used to study the effect of grid-connected DC distributed generation on power system small signal stability through simula-tion examples.The research shows that SOFC or PV affects the system damping characteristics by changing the power flow and the system equilibrium point.When the output increases,due to the increasing spinning reserve of the con-ventional unit,the damping characteristics are strongly related to the conventional unit,in which working in the oper-ation mode of reducing output will show a tendency to increase.%分布式电源类型及控制方式多样,致使含多种分布式电源的小扰动机电暂态分析的电网模型复杂,分析难度加大。针对应用较广的光伏和燃料电池两种分布式电源,在对其全阶状态空间模型的特征分析和电池动特性时间尺度分析的基础上,提出了前馈解耦控制下考虑电池U-I 外特性和逆变控制系统动特性的光伏发电系统降阶模型和忽略逆变系统快动态特性的燃料电池降阶模型,并应用于4机2区域系统并网小扰动分析。研究结果表明:直流DG并网主要通过改变系统潮流及平衡点影响系统阻尼特性;直流DG出力增加时,与采用降低出力增加旋转备用运行方式的常规机组强相关的模式阻尼特性会呈现增大的趋势。

  16. 风电并网用全功率变流器谐波电流抑制研究%Harmonic Currents Suppression for Full Size Power Grid-connection Converter Used for Wind Power Generation

    Institute of Scientific and Technical Information of China (English)

    姚骏; 夏先锋; 陈西寅; 廖勇

    2012-01-01

    电网低次谐波电压和电力电子器件的非线性将使得风电并网变流器产生较重的并网谐波电流,为改善风电并网用全功率变流器系统的输出电能质量,在详细分析网侧变换器的谐波数学模型的基础上,提出一种抑制并网低次(5、7、11、13次)谐波电流分量的交叉耦合控制策略。该控制策略通过在多同步旋转坐标系下检测各次并网谐波电流的直流分量,采用电流交叉耦合控制方式实现对各次谐波电流的准确控制,详细分析并设计谐波电流交叉耦合控制器。所提控制方案考虑了各次谐波电流回路的交叉耦合影响,可有效降低各次谐波电流以及基波电流之间的相互影响作用,有利于提高系统工作的稳定性。仿真和实验结果验证了所提控制方案的正确性和可行性。%The low order harmonic in grid voltage combined with the nonlinear characteristics of the power electronics devices will cause great amount of harmonic currents from the grid-connection converter used for wind power generation system, this will degrade the operational performance of the generation system. In order to improve the power quality of the full size power converter for the wind power generation system, a method was proposed to suppress the harmonic currents of the grid-side converter (GSC) in this paper. The harmonic mathematic model of the GSC wasinvestigated in detail, and the cross-coupling control strategy was proposed to suppress the low order (5th, 7th, llth, 13th) harmonic current components. In the proposed control scheme, the DC components of each order harmonic currents could be detected in the multiple synchronous rotating reference frames, and they could be accurately controlled to be zero with the cross-coupling current controller which was analyzed and designed. Taking into account the cross-coupling influence of the each order harmonic current circuit, the proposed control

  17. Microscopic calculations of elastic scattering between light nuclei based on a realistic nuclear interaction

    Energy Technology Data Exchange (ETDEWEB)

    Dohet-Eraly, Jeremy [F.R.S.-FNRS (Belgium); Sparenberg, Jean-Marc; Baye, Daniel, E-mail: jdoheter@ulb.ac.be, E-mail: jmspar@ulb.ac.be, E-mail: dbaye@ulb.ac.be [Physique Nucleaire et Physique Quantique, CP229, Universite Libre de Bruxelles (ULB), B-1050 Brussels (Belgium)

    2011-09-16

    The elastic phase shifts for the {alpha} + {alpha} and {alpha} + {sup 3}He collisions are calculated in a cluster approach by the Generator Coordinate Method coupled with the Microscopic R-matrix Method. Two interactions are derived from the realistic Argonne potentials AV8' and AV18 with the Unitary Correlation Operator Method. With a specific adjustment of correlations on the {alpha} + {alpha} collision, the phase shifts for the {alpha} + {alpha} and {alpha} + {sup 3}He collisions agree rather well with experimental data.

  18. A Sense of Responsibility in Realistic Children's Fiction.

    Science.gov (United States)

    Rochelle, Warren

    1991-01-01

    Discusses the qualities of successful realistic children's fiction and examines issues involved in writing and publishing for children. A historical overview of the image of children in fiction is presented; dealing with sensitive, emotional topics is discussed; and concerns of editors and publishers of children's fiction are addressed. (12…

  19. Realistic Fiction and the Social Studies. Children's Literature.

    Science.gov (United States)

    Mitchell-Powell, Brenda, Ed.

    1995-01-01

    Asserts that children's literature is an effective tool to access and present sophisticated social studies concepts in the elementary classroom. Maintains that realistic fiction can integrate the social sciences with philosophy and religion. Presents a bibliographic essay including children's books and teacher resources. (CFR)

  20. Creating a Realistic Context for Team Projects in HCI

    NARCIS (Netherlands)

    Koppelman, H.; Dijk, van E.M.A.G.

    2006-01-01

    Team projects are nowadays common practice in HCI education. This paper focuses on the role of clients and users in team projects in introductory HCI courses. In order to provide projects with a realistic context we invite people from industry to serve as clients for the student teams. Some of them

  1. The Potential and Challenges of Critical Realist Ethnography

    Science.gov (United States)

    Barron, Ian

    2013-01-01

    This article revisits the critical realist ethnographic process that was adopted in my doctoral thesis, which was concerned with the experiences of ethnic identity of white British and Pakistani British children as they started kindergarten in the northwest of England. The article focuses on the ethnography that emerged from the visits that I…

  2. Hope in Janusz Korczak's Pedagogy of Realistic Idealism

    Science.gov (United States)

    Silverman, Marc

    2017-01-01

    This article explores the approach of "Realistic Idealism" to moral education developed by the humanist-progressive moral educator Janusz Korczak, and the role hope plays in it. This pair of terms seems to be an oxymoron. However, their employment is intentional and the article will demonstrate their dialectical interdependence:…

  3. "Shut My Mouth Wide Open": Realistic Fiction and Social Action.

    Science.gov (United States)

    Tyson, Cynthia A.

    1999-01-01

    Shares the responses of seven urban, male, African-American fifth graders to contemporary realistic fiction, discussing how the tying of this literature to the events in the boys' lives had the potential to move them toward social action. The paper examines the following: literature as a catalyst, reader responses to texts, critical literacy, and…

  4. Realistic glottal motion and airflow rate during human breathing.

    Science.gov (United States)

    Scheinherr, Adam; Bailly, Lucie; Boiron, Olivier; Lagier, Aude; Legou, Thierry; Pichelin, Marine; Caillibotte, Georges; Giovanni, Antoine

    2015-09-01

    The glottal geometry is a key factor in the aerosol delivery efficiency for treatment of lung diseases. However, while glottal vibrations were extensively studied during human phonation, the realistic glottal motion during breathing is poorly understood. Therefore, most current studies assume an idealized steady glottis in the context of respiratory dynamics, and thus neglect the flow unsteadiness related to this motion. This is particularly important to assess the aerosol transport mechanisms in upper airways. This article presents a clinical study conducted on 20 volunteers, to examine the realistic glottal motion during several breathing tasks. Nasofibroscopy was used to investigate the glottal geometrical variations simultaneously with accurate airflow rate measurements. In total, 144 breathing sequences of 30s were recorded. Regarding the whole database, two cases of glottal time-variations were found: "static" or "dynamic" ones. Typically, the peak value of glottal area during slow breathing narrowed from 217 ± 54 mm(2) (mean ± STD) during inspiration, to 178 ± 35 mm(2) during expiration. Considering flow unsteadiness, it is shown that the harmonic approximation of the airflow rate underevaluates the inertial effects as compared to realistic patterns, especially at the onset of the breathing cycle. These measurements provide input data to conduct realistic numerical simulations of laryngeal airflow and particle deposition. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

  5. Using a Realist Research Methodology in Policy Analysis

    Science.gov (United States)

    Lourie, Megan; Rata, Elizabeth

    2017-01-01

    The article describes the usefulness of a realist methodology in linking sociological theory to empirically obtained data through the development of a methodological device. Three layers of analysis were integrated: 1. the findings from a case study about Maori language education in New Zealand; 2. the identification and analysis of contradictions…

  6. Realistic Fiction and the Social Studies. Children's Literature.

    Science.gov (United States)

    Mitchell-Powell, Brenda, Ed.

    1995-01-01

    Asserts that children's literature is an effective tool to access and present sophisticated social studies concepts in the elementary classroom. Maintains that realistic fiction can integrate the social sciences with philosophy and religion. Presents a bibliographic essay including children's books and teacher resources. (CFR)

  7. Representations of Adoption in Contemporary Realistic Fiction for Young Adults

    Science.gov (United States)

    Parsons, Sue Christian; Fuxa, Robin; Kander, Faryl; Hardy, Dana

    2017-01-01

    In this critical content analysis of thirty-seven contemporary realistic fiction books about adoption, the authors examine how adoption and adoptive families are depicted in young adult (YA) literature. The critical literacy theoretical frame brings into focus significant social implications of these depictions as the researchers illuminate and…

  8. A Sense of Responsibility in Realistic Children's Fiction.

    Science.gov (United States)

    Rochelle, Warren

    1991-01-01

    Discusses the qualities of successful realistic children's fiction and examines issues involved in writing and publishing for children. A historical overview of the image of children in fiction is presented; dealing with sensitive, emotional topics is discussed; and concerns of editors and publishers of children's fiction are addressed. (12…

  9. "Shut My Mouth Wide Open": Realistic Fiction and Social Action.

    Science.gov (United States)

    Tyson, Cynthia A.

    1999-01-01

    Shares the responses of seven urban, male, African-American fifth graders to contemporary realistic fiction, discussing how the tying of this literature to the events in the boys' lives had the potential to move them toward social action. The paper examines the following: literature as a catalyst, reader responses to texts, critical literacy, and…

  10. Highly realistic, immersive training for navy corpsmen: preliminary results.

    Science.gov (United States)

    Booth-Kewley, Stephanie; McWhorter, Stephanie K

    2014-12-01

    Highly realistic, immersive training has been developed for Navy corpsmen based on the success of the Infantry Immersion Trainer. This new training is built around scenarios that are designed to depict real-life, operational situations. Each scenario used in the training includes sights, sounds, smells, and distractions to simulate realistic and challenging combat situations. The primary objective of this study was to assess corpsmen participants' satisfaction with highly realistic training. The study sample consisted of 434 male Navy service members attending Field Medical Training Battalion-West, Camp Pendleton, California. Corpsmen participants completed surveys after receiving the training. Participants expressed high levels of satisfaction with the training overall and with several specific elements of the training. The element of the training that the corpsmen rated the highest was the use of live actors. The vast majority of the participants reported that the training had increased their overall confidence about being successful corpsmen and had strengthened their confidence in their ability to provide care under pressure. Additional research should extend highly realistic training to other military medical provider populations. Reprint & Copyright © 2014 Association of Military Surgeons of the U.S.

  11. Using Concrete and Realistic Data in Evaluating Initial Visualization Designs

    DEFF Research Database (Denmark)

    Knudsen, Søren; Pedersen, Jeppe Gerner; Herdal, Thor

    2016-01-01

    We explore means of designing and evaluating initial visualization ideas, with concrete and realistic data in cases where data is not readily available. Our approach is useful in exploring new domains and avenues for visualization, and contrasts other visualization work, which typically operate u...

  12. How outcomes are achieved through patient portals: A realist review

    NARCIS (Netherlands)

    E.T. Otte-Trojel (Eva Terese); A.A. de Bont (Antoinette); T.G. Rundall (Thomas); J.J. van de Klundert (Joris)

    2014-01-01

    textabstractObjective: To examine how patient portals contribute to health service delivery and patient outcomes. The specific aims were to examine how outcomes are produced, and how variations in outcomes can be explained. Methods: We used a realist review method, which aims to describe how 'an

  13. Realistic Visualization of Virtual Views and Virtual Cinema

    DEFF Research Database (Denmark)

    Livatino, Salvatore

    2005-01-01

    Realistic Virtual View Visualization is a new field of research which has received increasing attention in recent years. It is strictly related to the increased popularity of virtual reality and the spread of its applications, among which virtual photography and cinematography. The use of compute...

  14. Improving Mathematics Teaching in Kindergarten with Realistic Mathematical Education

    Science.gov (United States)

    Papadakis, Stamatios; Kalogiannakis, Michail; Zaranis, Nicholas

    2017-01-01

    The present study investigates and compares the influence of teaching Realistic Mathematics on the development of mathematical competence in kindergarten. The sample consisted of 231 Greek kindergarten students. For the implementation of the survey, we conducted an intervention, which included one experimental and one control group. Children in…

  15. Using a Realist Research Methodology in Policy Analysis

    Science.gov (United States)

    Lourie, Megan; Rata, Elizabeth

    2017-01-01

    The article describes the usefulness of a realist methodology in linking sociological theory to empirically obtained data through the development of a methodological device. Three layers of analysis were integrated: 1. the findings from a case study about Maori language education in New Zealand; 2. the identification and analysis of contradictions…

  16. An Overview of Westinghouse Realistic Large Break LOCA Evaluation Model

    Directory of Open Access Journals (Sweden)

    Cesare Frepoli

    2008-01-01

    Full Text Available Since the 1988 amendment of the 10 CFR 50.46 rule in 1988, Westinghouse has been developing and applying realistic or best-estimate methods to perform LOCA safety analyses. A realistic analysis requires the execution of various realistic LOCA transient simulations where the effect of both model and input uncertainties are ranged and propagated throughout the transients. The outcome is typically a range of results with associated probabilities. The thermal/hydraulic code is the engine of the methodology but a procedure is developed to assess the code and determine its biases and uncertainties. In addition, inputs to the simulation are also affected by uncertainty and these uncertainties are incorporated into the process. Several approaches have been proposed and applied in the industry in the framework of best-estimate methods. Most of the implementations, including Westinghouse, follow the Code Scaling, Applicability and Uncertainty (CSAU methodology. Westinghouse methodology is based on the use of the WCOBRA/TRAC thermal-hydraulic code. The paper starts with an overview of the regulations and its interpretation in the context of realistic analysis. The CSAU roadmap is reviewed in the context of its implementation in the Westinghouse evaluation model. An overview of the code (WCOBRA/TRAC and methodology is provided. Finally, the recent evolution to nonparametric statistics in the current edition of the W methodology is discussed. Sample results of a typical large break LOCA analysis for a PWR are provided.

  17. D-term Spectroscopy in Realistic Heterotic-String Models

    CERN Document Server

    Dedes, Athanasios

    2000-01-01

    The emergence of free fermionic string models with solely the MSSM charged spectrum below the string scale provides further evidence to the assertion that the true string vacuum is connected to the Z_2 x Z_2 orbifold in the vicinity of the free fermionic point in the Narain moduli space. An important property of the Z_2 x Z_2 orbifold is the cyclic permutation symmetry between the three twisted sectors. If preserved in the three generations models the cyclic permutation symmetry results in a family universal anomalous U(1)_A, which is instrumental in explaining squark degeneracy, provided that the dominant component of supersymmetry breaking arises from the U(1)_A D-term. Interestingly, the contribution of the family--universal D_A-term to the squark masses may be intra-family non-universal, and may differ from the usual (universal) boundary conditions assumed in the MSSM. We contemplate how D_A--term spectroscopy may be instrumental in studying superstring models irrespective of our ignorance of the details ...

  18. The solar-stellar connection

    Science.gov (United States)

    Giampapa, Mark S.

    2016-07-01

    A review of some principal results achieved in the area of stellar astrophysics with its origins in solar physics - the Solar-Stellar Connection - is presented from the perspective of an observational astronomer. The historical origins of the Solar-Stellar Connection are discussed followed by a review of key results from observations of stellar cycles analogous to the solar cycle in terms of parameters relevant to dynamo theory. A review of facets of angular momentum evolution and irradiance variations, each of which is determined by emergent, dynamo-generated magnetic fields, is given. Recent considerations of the impacts of stellar magnetic activity on the ambient radiative and energetic particle environment of the habitable zone of exoplanet systems are summarized. Some anticipated directions of the Solar-Stellar Connection in the new era of astronomy as defined by the advent of transformative facilities are presented.

  19. Time-scale invariance as an emergent property in a perceptron with realistic, noisy neurons

    Science.gov (United States)

    Buhusi, Catalin V.; Oprisan, Sorinel A.

    2013-01-01

    In most species, interval timing is time-scale invariant: errors in time estimation scale up linearly with the estimated duration. In mammals, time-scale invariance is ubiquitous over behavioral, lesion, and pharmacological manipulations. For example, dopaminergic drugs induce an immediate, whereas cholinergic drugs induce a gradual, scalar change in timing. Behavioral theories posit that time-scale invariance derives from particular computations, rules, or coding schemes. In contrast, we discuss a simple neural circuit, the perceptron, whose output neurons fire in a clockwise fashion (interval timing) based on the pattern of coincidental activation of its input neurons. We show numerically that time-scale invariance emerges spontaneously in a perceptron with realistic neurons, in the presence of noise. Under the assumption that dopaminergic drugs modulate the firing of input neurons, and that cholinergic drugs modulate the memory representation of the criterion time, we show that a perceptron with realistic neurons reproduces the pharmacological clock and memory patterns, and their time-scale invariance, in the presence of noise. These results suggest that rather than being a signature of higher-order cognitive processes or specific computations related to timing, time-scale invariance may spontaneously emerge in a massively-connected brain from the intrinsic noise of neurons and circuits, thus providing the simplest explanation for the ubiquity of scale invariance of interval timing. PMID:23518297

  20. Developing a realistic model for the training of the laparoscopic Nissen fundoplication.

    Science.gov (United States)

    Botden, Sanne M B I; Goossens, Richard; Jakimowicz, Jack J

    2010-06-01

    A realistic human anatomy simulation model developed for training to perform laparoscopic Nissen fundoplication (antireflux surgery) could reduce the need and use of animal tissue models. This article elaborates the designing process of this model and the development process used to create the abdominal organs with realistic haptic feedback. Before developing the artificial organs, first the mechanical characteristics of human tissue were examined. Next, separate animal organs that resembled these characteristics the closest was used to create the model. The haptic feedback of the intra-abdominal organs variables studied included tissue, geometry, and context. The stress-strain curves of the different tissues were calculated and compared with the properties of industrial materials to find the best material for the production of the organs. The aspects that influenced haptic feedback as determined above and used to select the most promising material groups were: E-modulus, density, coefficient of friction, sensitivity to tearing, wall thickness, and shelf life. Based on these criteria, silicone and latex materials mimiked human tissue best. Changeable velvet rope was used for connections of the organs to the surface and other simulated tissue. A reusable modular model of the upper abdomen anatomy with haptic properties was created for training of upper gastrointestinal surgery laparoscopic procedures, such as the Nissen fundoplication.

  1. Further analysis of the connected moments expansion

    Energy Technology Data Exchange (ETDEWEB)

    Amore, Paolo; Rodriguez, Martin [Facultad de Ciencias, Universidad de Colima, Bernal Diaz del Castillo 340, Colima, Colima (Mexico); Fernandez, Francisco M, E-mail: paolo.amore@gmail.com, E-mail: fernande@quimica.unlp.edu.ar, E-mail: martinalexander.rv@gmail.com [INIFTA (UNLP, CCT La Plata-CONICET), Division Quimica Teorica, Blvd. 113 S/N, Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina)

    2011-12-16

    By means of simple quantum-mechanical models we show that under certain conditions the main assumptions of the connected moments expansion (CMX) are no longer valid. In particular, we consider two-level systems: the harmonic oscillator and the pure quartic oscillator. Although derived from such simple models, we think that the results of this investigation may be of utility in future applications of the approach to realistic problems. We show that a straightforward analysis of the CMX exponential parameters may provide a clear indication of the success of the approach. (paper)

  2. Effect of geometry on concentration polarization in realistic heterogeneous permselective systems

    CERN Document Server

    Green, Yoav; Yossifon, Gilad

    2014-01-01

    This study extends previous analytical solutions of concentration-polarization occurring solely in the depleted region, to the more realistic geometry consisting of a three dimensional (3D) heterogeneous ion-permselective medium connecting two opposite microchambers (i.e. 3 layers system). Under the local electro-neutrality approximation, the separation of variable methods is used to derive an analytical solution of the electro-diffusive problem for the two opposing asymmetric microchambers. Assuming an ideal permselective medium allows for the analytic calculation of the 3D concentration and electric potential distributions as well as a current-voltage relation. It is shown that any asymmetry in the microchamber geometries will result in current rectification. Moreover, it is demonstrated that for non-negligible microchamber resistances the conductance does not exhibit the expected saturation at low concentrations but instead shows a continuous decrease. The results are intended to facilitate a more direct c...

  3. Photovoltaic systems connected to electric power like distributed generators: the recent situation at the PVPS-IEA and at the Brazilian scenario; Sistemas fotovoltaicos conectados a rede eletrica como geradores distribuidos: a situacao recente no PVPS-IEA e no cenario brasileiro

    Energy Technology Data Exchange (ETDEWEB)

    Quaglia, Renato Brito; Oliveira, Sergio Henrique Ferreira de [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil). Centro de Engenharia, Modelagem e Ciencias Sociais Aplicadas. Programa de Pos-Graduacao em Energia], email: renato.quaglia@ufabc.edu.br

    2008-07-01

    In this paper it is considered the use of Distributed Generation (GD) as a further option to centralized generation of electricity and treats its photovoltaic systems connected to power network (SFCR's) technology as an option in this interesting 'new' model to plan the expansion of the brazilian electrical energy matrix, mainly in urban centres. For this reason, it was necessary to mention the main characteristics of this technology as distributed generators, and the profile of his generation when connected in homes and commercial buildings. Moreover, it presents the benefits that these systems can offer the electricity sector, society and the economy. In the study of Photovoltaic Power Systems Programme (PVPS), specifically the situation of this technology in Germany, realized that the creation of mechanisms of financial incentives provided to implement some of the main barriers associated with the integration of photovoltaic systems as distributed generators. In assessing the Brazilian context, there was the incipient photovoltaic market in the country, even taking some systems already installed, note that the vast majority are intended for studies of Research and Development. There is also the exploitation of photovoltaic systems connected to the network for use in homes, businesses or industries, probably because of the lack of incentive programs for SFCR's. Although there is a programme of incentives to Alternative Sources of Electricity - Proinfa, it does not consider the SFCR's in its guidelines for qualification, only the wind systems, small hydroelectric plants and systems powered by biomass. Point is, therefore, the need for the creation of an energy policy that encourages the Brazilian market photovoltaic, more precisely a policy of offering incentives conditions of maturity of this technology when connected to the network - technical standards, decrease costs, creation of hand of specialized work, installation of manufacturers

  4. Development of a realistic, dynamic digital brain phantom for CT perfusion validation

    Science.gov (United States)

    Divel, Sarah E.; Segars, W. Paul; Christensen, Soren; Wintermark, Max; Lansberg, Maarten G.; Pelc, Norbert J.

    2016-03-01

    Physicians rely on CT Perfusion (CTP) images and quantitative image data, including cerebral blood flow, cerebral blood volume, and bolus arrival delay, to diagnose and treat stroke patients. However, the quantification of these metrics may vary depending on the computational method used. Therefore, we have developed a dynamic and realistic digital brain phantom upon which CTP scans can be simulated based on a set of ground truth scenarios. Building upon the previously developed 4D extended cardiac-torso (XCAT) phantom containing a highly detailed brain model, this work consisted of expanding the intricate vasculature by semi-automatically segmenting existing MRA data and fitting nonuniform rational B-spline surfaces to the new vessels. Using time attenuation curves input by the user as reference, the contrast enhancement in the vessels changes dynamically. At each time point, the iodine concentration in the arteries and veins is calculated from the curves and the material composition of the blood changes to reflect the expected values. CatSim, a CT system simulator, generates simulated data sets of this dynamic digital phantom which can be further analyzed to validate CTP studies and post-processing methods. The development of this dynamic and realistic digital phantom provides a valuable resource with which current uncertainties and controversies surrounding the quantitative computations generated from CTP data can be examined and resolved.

  5. Realistic Modeling of Multi-Scale MHD Dynamics of the Solar Atmosphere

    Science.gov (United States)

    Kitiashvili, Irina; Mansour, Nagi N.; Wray, Alan; Couvidat, Sebastian; Yoon, Seokkwan; Kosovichev, Alexander

    2014-01-01

    Realistic 3D radiative MHD simulations open new perspectives for understanding the turbulent dynamics of the solar surface, its coupling to the atmosphere, and the physical mechanisms of generation and transport of non-thermal energy. Traditionally, plasma eruptions and wave phenomena in the solar atmosphere are modeled by prescribing artificial driving mechanisms using magnetic or gas pressure forces that might arise from magnetic field emergence or reconnection instabilities. In contrast, our 'ab initio' simulations provide a realistic description of solar dynamics naturally driven by solar energy flow. By simulating the upper convection zone and the solar atmosphere, we can investigate in detail the physical processes of turbulent magnetoconvection, generation and amplification of magnetic fields, excitation of MHD waves, and plasma eruptions. We present recent simulation results of the multi-scale dynamics of quiet-Sun regions, and energetic effects in the atmosphere and compare with observations. For the comparisons we calculate synthetic spectro-polarimetric data to model observational data of SDO, Hinode, and New Solar Telescope.

  6. The role of topography in the transformation of spatiotemporal patterns by a large-scale, biologically realistic model of the rat dentate gyrus.

    Science.gov (United States)

    Yu, Gene J; Hendrickson, Phillip J; Robinson, Brian S; Song, Dong; Berger, Theodore W

    2013-01-01

    A large-scale, biologically realistic, computational model of the rat hippocampus is being constructed to study the input-output transformation that the hippocampus performs. In the initial implementation, the layer II entorhinal cortex neurons, which provide the major input to the hippocampus, and the granule cells of the dentate gyrus, which receive the majority of the input, are modeled. In a previous work, the topography, or the wiring diagram, connecting these two populations had been derived and implemented. This paper explores the consequences of two features of the topography, the distribution of the axons and the size of the neurons' axon terminal fields. The topography converts streams of independently generated random Poisson trains into structured spatiotemporal patterns through spatiotemporal convergence achievable by overlapping axon terminal fields. Increasing the axon terminal field lengths allowed input to converge over larger regions of space resulting in granule activation across a greater area but did not increase the total activity as a function of time as the number of targets per input remained constant. Additional simulations demonstrated that the total distribution of spikes in space depends not on the distribution of the presynaptic axons but the distribution of the postsynaptic population. Analyzing spike counts emphasizes the importance of the postsynaptic distribution, but it ignores the fact that each individual input may be carrying unique information. Therefore, a metric should be created that relates and tracks individual inputs as they are propagated and integrated through hippocampus.

  7. Synthetic neuronal datasets for benchmarking directed functional connectivity metrics

    National Research Council Canada - National Science Library

    Rodrigues, João; Andrade, Alexandre

    2015-01-01

    Background. Datasets consisting of synthetic neural data generated with quantifiable and controlled parameters are a valuable asset in the process of testing and validating directed functional connectivity metrics...

  8. Role-playing for more realistic technical skills training.

    Science.gov (United States)

    Nikendei, C; Zeuch, A; Dieckmann, P; Roth, C; Schäfer, S; Völkl, M; Schellberg, D; Herzog, W; Jünger, J

    2005-03-01

    Clinical skills are an important and necessary part of clinical competence. Simulation plays an important role in many fields of medical education. Although role-playing is common in communication training, there are no reports about the use of student role-plays in the training of technical clinical skills. This article describes an educational intervention with analysis of pre- and post-intervention self-selected student survey evaluations. After one term of skills training, a thorough evaluation showed that the skills-lab training did not seem very realistic nor was it very demanding for trainees. To create a more realistic training situation and to enhance students' involvement, case studies and role-plays with defined roles for students (i.e. intern, senior consultant) were introduced into half of the sessions. Results of the evaluation in the second term showed that sessions with role-playing were rated significantly higher than sessions without role-playing.

  9. Towards a Realistic Parsing of the Feynman Path Integral

    Directory of Open Access Journals (Sweden)

    Ken Wharton

    2016-01-01

    Full Text Available The Feynman path integral does not allow a one real path interpretation, because the quantum amplitudes contribute to probabilities in a non-separable manner. The opposite extreme, all paths happen, is not a useful or informative account. In this paper it is shown that an intermediate parsing of the path integral, into realistic non-interfering possibilities, is always available. Each realistic possibility formally corresponds to numerous particle paths, but is arguably best interpreted as a spacetime-valued field. Notably, one actual field history can always be said to occur, although it will generally not have an extremized action. The most obvious concerns with this approach are addressed, indicating necessary follow-up research. But without obvious showstoppers, it seems plausible that the path integral might be reinterpreted to explain quantum phenomena in terms of Lorentz covariant field histories.Quanta 2016; 5: 1–11.

  10. A general realistic treatment of the disk paradox

    CERN Document Server

    Pantazis, George

    2016-01-01

    Mechanical angular momentum is not conserved in systems involving electromagnetic fields with non-zero electromagnetic field angular momentum. Conservation is restored only if the total (mechanical and field) angular momentum is considered. Previous studies have investigated this effect, known as "Feynman's Electromagnetic Paradox" or simply "Disk Paradox" in the context of idealized systems (infinite or infinitesimal solenoids and charged cylinders \\etc). In the present analysis we generalize previous studies by considering more realistic systems with finite components and demonstrating explicitly the conservation of the total angular momentum. This is achieved by expressing both the mechanical and the field angular momentum in terms of charges and magnetic field fluxes through various system components. Using this general expression we demonstrate explicitly the conservation of total angular momentum in both idealized and realistic systems (finite solenoid concentric with two charged long cylinders) taking ...

  11. Bell's inequalities with realistic noise for polarization-entangled photons

    CERN Document Server

    Cabello, A; Lamas-Linares, A; Cabello, Adan; Feito, Alvaro; Lamas-Linares, Antia

    2005-01-01

    Contrary to the usual assumption that the experimental preparation of pure entangled states can be described by mixed states due to white noise, a more realistic description for polarization-entangled states produced by parametric down-conversion is that they are mixed states due to decoherence in a preferred polarization basis. This distinction between white and colored noise is crucial when we look for maximal violations of Bell's inequalities for two-qubit and two-qutrit entangled states. We find that violations of Bell's inequalities with realistic noise for polarization-entangled photons are extremely robust for colored noise, whereas this is not the case for white noise. In addition, we study the difference between white and colored noise for maximal violations of Bell's inequalities for three and four-qubit entangled states.

  12. Modeling of biofuel pellets torrefaction in a realistic geometry

    Directory of Open Access Journals (Sweden)

    Artiukhina Ekaterina

    2016-01-01

    Full Text Available Low temperature pyrolysis also known as torrefaction is considered as a promising pretreatment technology for conversion of biomass into a solid biofuel with enhanced properties in terms of lower moisture and volatile matter content, hydrophobicity and increased heating value. A thermal treatment leads to a non-uniform temperature field and chemical reactions proceeding unevenly within the pellets. However the temperature is assumed to be uniform in the pellets in the majority of models. Here we report on the model of single pellet biomass torrefaction, taking into account the heat transfer and chemical kinetics in the realistic geometry. The evolution of temperature and material density in the non-stationary thermo-chemical process is described by the system of non-linear partial differential equations. The model describing the high-temperature drying of biomass pellet was also introduced. The importance of boundary effects in realistic simulations of biomass pellets torrefaction is underlined in this work.

  13. Applying a realistic evaluation model to occupational safety interventions

    DEFF Research Database (Denmark)

    Pedersen, Louise Møller

    2017-01-01

    of occupational safety interventions. Conclusion: The revised realistic evaluation model can help safety science forward in identifying key factors for the success of occupational safety interventions. However, future research should strengthen the link between the immediate intervention results and outcome.......Background: Recent literature characterizes occupational safety interventions as complex social activities, applied in complex and dynamic social systems. Hence, the actual outcomes of an intervention will vary, depending on the intervention, the implementation process, context, personal...... characteristics of key actors (defined mechanisms), and the interplay between them, and can be categorized as expected or unexpected. However, little is known about ’how’ to include context and mechanisms in evaluations of intervention effectiveness. A revised realistic evaluation model has been introduced...

  14. Large-scale neural model validation of partial correlation analysis for effective connectivity investigation in functional MRI.

    Science.gov (United States)

    Marrelec, G; Kim, J; Doyon, J; Horwitz, B

    2009-03-01

    Recent studies of functional connectivity based upon blood oxygen level dependent functional magnetic resonance imaging have shown that this technique allows one to investigate large-scale functional brain networks. In a previous study, we advocated that data-driven measures of effective connectivity should be developed to bridge the gap between functional and effective connectivity. To attain this goal, we proposed a novel approach based on the partial correlation matrix. In this study, we further validate the use of partial correlation analysis by employing a large-scale, neurobiologically realistic neural network model to generate simulated data that we analyze with both structural equation modeling (SEM) and the partial correlation approach. Unlike real experimental data, where the interregional anatomical links are not necessarily known, the links between the nodes of the network model are fully specified, and thus provide a standard against which to judge the results of SEM and partial correlation analyses. Our results show that partial correlation analysis from the data alone exhibits patterns of effective connectivity that are similar to those found using SEM, and both are in agreement with respect to the underlying neuroarchitecture. Our findings thus provide a strong validation for the partial correlation method.

  15. Highly Realistic, Immersive Training for Navy Corpsmen: Preliminary Results

    Science.gov (United States)

    2014-12-01

    the actors who play the role of casualties are actual amputees , some of whom were injured in combat. The scenarios require that corpsmen demonstrate...black (9%), Hispanic (5%), and other race groups. A quarter of respon- dents (25%) marked “mixed or multiple races.” Measures To evaluate satisfaction...feel realistic Participants’ Suggestions for Improving the Training Give more scenarios and more time at MOUT Do the training multiple times, so that

  16. Music therapy for palliative care: A realist review.

    OpenAIRE

    McConnell, T; Porter, Samuel

    2016-01-01

    OBJECTIVE: Music therapy has experienced a rising demand as an adjunct therapy for symptom management among palliative care patients. We conducted a realist review of the literature to develop a greater understanding of how music therapy might benefit palliative care patients and the contextual mechanisms that promote or inhibit its successful implementation. METHOD: We searched electronic databases (CINAHL, Embase, Medline, and PsychINFO) for literature containing information on music therap...

  17. Music therapy for palliative care: A realist review

    OpenAIRE

    McConnell, T.; Porter, Samuel

    2016-01-01

    OBJECTIVE: Music therapy has experienced a rising demand as an adjunct therapy for symptom management among palliative care patients. We conducted a realist review of the literature to develop a greater understanding of how music therapy might benefit palliative care patients and the contextual mechanisms that promote or inhibit its successful implementation. METHOD: We searched electronic databases (CINAHL, Embase, Medline, and PsychINFO) for literature containing information on music therap...

  18. Simulation of human ischemic stroke in realistic 3D geometry

    Science.gov (United States)

    Dumont, Thierry; Duarte, Max; Descombes, Stéphane; Dronne, Marie-Aimée; Massot, Marc; Louvet, Violaine

    2013-06-01

    In silico research in medicine is thought to reduce the need for expensive clinical trials under the condition of reliable mathematical models and accurate and efficient numerical methods. In the present work, we tackle the numerical simulation of reaction-diffusion equations modeling human ischemic stroke. This problem induces peculiar difficulties like potentially large stiffness which stems from the broad spectrum of temporal scales in the nonlinear chemical source term as well as from the presence of steep spatial gradients in the reaction fronts, spatially very localized. Furthermore, simulations on realistic 3D geometries are mandatory in order to describe correctly this type of phenomenon. The main goal of this article is to obtain, for the first time, 3D simulations on realistic geometries and to show that the simulation results are consistent with those obtain in experimental studies or observed on MRI images in stroke patients. For this purpose, we introduce a new resolution strategy based mainly on time operator splitting that takes into account complex geometry coupled with a well-conceived parallelization strategy for shared memory architectures. We consider then a high order implicit time integration for the reaction and an explicit one for the diffusion term in order to build a time operator splitting scheme that exploits efficiently the special features of each problem. Thus, we aim at solving complete and realistic models including all time and space scales with conventional computing resources, that is on a reasonably powerful workstation. Consequently and as expected, 2D and also fully 3D numerical simulations of ischemic strokes for a realistic brain geometry, are conducted for the first time and shown to reproduce the dynamics observed on MRI images in stroke patients. Beyond this major step, in order to improve accuracy and computational efficiency of the simulations, we indicate how the present numerical strategy can be coupled with spatial

  19. An Argument Against the Realistic Interpretation of the Wave Function

    Science.gov (United States)

    Rovelli, Carlo

    2016-10-01

    Testable predictions of quantum mechanics are invariant under time reversal. But the evolution of the quantum state in time is not so, neither in the collapse nor in the no-collapse interpretations of the theory. This is a fact that challenges any realistic interpretation of the quantum state. On the other hand, this fact raises no difficulty if we interpret the quantum state as a mere calculation device, bookkeeping past real quantum events.

  20. Extending AI Planning to Solve more Realistic Problems

    OpenAIRE

    Zalaket, Joseph

    2008-01-01

    In this chapter, we have presented multiple extensions for classical planning algorithms in order to allow them to solve more realistic problems. This kind of problems can contain any type of knowledge and can require complex handling which is not yet supported by the existing planning algorithms. Some complicated problems can be expressed with the recent extensions to PDDL language, but the main lack remains especially because of the incapacity of the current planners. We have suggested and ...

  1. Investigation of the Airflow inside Realistic and Semi-Realistic Replicas of Human Airways

    Directory of Open Access Journals (Sweden)

    Lizal Frantisek

    2015-01-01

    Full Text Available Measurement of velocity in human lungs during breathing cycle is a challenging task for researchers, since the measuring location is accessible only with significant difficulties. A special measuring rig consisting of optically transparent replica of human lungs, breathing simulator, particle generator and Laser-Doppler anemometer was developed and used for investigation of the velocity in specific locations of lungs during simulated breathing cycle. Experiments were performed on two different replicas of human lungs in corresponding measuring points to facilitate the analysis of the influence of the geometry and its simplification on the flow. The analysis of velocity course and turbulence intensity revealed that special attention should be devoted to the modelling of vocal cords position during breathing, as the position of laryngeal jet created by vocal cords significantly influences velocity profiles in trachea. The shapes of velocity courses during expiration proved to be consistent for both replicas; however magnitudes of peak expiratory velocity differ between the corresponding measuring points in both the replicas.

  2. MRXCAT: Realistic numerical phantoms for cardiovascular magnetic resonance.

    Science.gov (United States)

    Wissmann, Lukas; Santelli, Claudio; Segars, William P; Kozerke, Sebastian

    2014-08-20

    Computer simulations are important for validating novel image acquisition and reconstruction strategies. In cardiovascular magnetic resonance (CMR), numerical simulations need to combine anatomical information and the effects of cardiac and/or respiratory motion. To this end, a framework for realistic CMR simulations is proposed and its use for image reconstruction from undersampled data is demonstrated. The extended Cardiac-Torso (XCAT) anatomical phantom framework with various motion options was used as a basis for the numerical phantoms. Different tissue, dynamic contrast and signal models, multiple receiver coils and noise are simulated. Arbitrary trajectories and undersampled acquisition can be selected. The utility of the framework is demonstrated for accelerated cine and first-pass myocardial perfusion imaging using k-t PCA and k-t SPARSE. MRXCAT phantoms allow for realistic simulation of CMR including optional cardiac and respiratory motion. Example reconstructions from simulated undersampled k-t parallel imaging demonstrate the feasibility of simulated acquisition and reconstruction using the presented framework. Myocardial blood flow assessment from simulated myocardial perfusion images highlights the suitability of MRXCAT for quantitative post-processing simulation. The proposed MRXCAT phantom framework enables versatile and realistic simulations of CMR including breathhold and free-breathing acquisitions.

  3. An anatomically realistic temperature phantom for radiofrequency heating measurements.

    Science.gov (United States)

    Graedel, Nadine N; Polimeni, Jonathan R; Guerin, Bastien; Gagoski, Borjan; Wald, Lawrence L

    2015-01-01

    An anthropomorphic phantom with realistic electrical properties allows for a more accurate reproduction of tissue current patterns during excitation. A temperature map can then probe the worst-case heating expected in the unperfused case. We describe an anatomically realistic human head phantom that allows rapid three-dimensional (3D) temperature mapping at 7T. The phantom was based on hand-labeled anatomical imaging data and consists of four compartments matching the corresponding human tissues in geometry and electrical properties. The increases in temperature resulting from radiofrequency excitation were measured with MR thermometry using a temperature-sensitive contrast agent (TmDOTMA(-)) validated by direct fiber optic temperature measurements. Acquisition of 3D temperature maps of the full phantom with a temperature accuracy better than 0.1°C was achieved with an isotropic resolution of 5 mm and acquisition times of 2-4 minutes. Our results demonstrate the feasibility of constructing anatomically realistic phantoms with complex geometries incorporating the ability to measure accurate temperature maps in the phantom. The anthropomorphic temperature phantom is expected to provide a useful tool for the evaluation of the heating effects of both conventional and parallel transmit pulses and help validate electromagnetic and temperature simulations. © 2014 Wiley Periodicals, Inc.

  4. Depigmented Skin and Phantom Color Measurements for Realistic Prostheses

    Science.gov (United States)

    Tanner, Paul; Leachman, Sancy; Boucher, Kenneth; Ozçelik, Tunçer Burak

    2013-01-01

    Purpose The purpose of this study was to test the hypothesis that regardless of human skin phototype, areas of depigmented skin, as seen in vitiligo, are optically indistinguishable among skin phototypes. The average of the depigmented skin measurements can be used to develop the base color of realistic prostheses. Methods and Materials Data from 20 of 32 recruited vitiligo study participants. Diffuse reflectance spectroscopy measurements were made from depigmented skin and adjacent pigmented skin, then compared to 66 pigmented polydimethylsiloxane phantoms to determine pigment concentrations in turbid media for making realistic facial prostheses. Results The Area Under spectral intensity Curve (AUC) was calculated for average spectroscopy measurements of pigmented sites in relation to skin phototype (p=0.0505) and depigmented skin in relation to skin phototype (p=0.59). No significant relationship exists between skin phototypes and depigmented skin spectroscopy measurements. The average of the depigmented skin measurements (AUC 19,129) was the closest match to phantom 6.4 (AUC 19,162) Conclusions Areas of depigmented skin are visibly indistinguishable per skin phototype, yet spectrometry shows that depigmented skin measurements varied and were unrelated to skin phototype. Possible sources of optical variation of depigmented skin include age, body site, blood flow, quantity/quality of collagen, and other chromophores. The average of all depigmented skin measurements can be used to derive the pigment composition and concentration for realistic facial prostheses. PMID:23750920

  5. Relating realist metatheory to issues of gender and mental health.

    Science.gov (United States)

    Bergin, M; Wells, John S G; Owen, Sara

    2010-06-01

    This paper seeks to advance the debate that considers critical realism as an alternative approach for understanding gender and mental health and its relatedness to mental health research and practice. The knowledge base of how 'sex' and 'gender' affect mental health and illness is expanding. However, the way we conceptualize gender is significant and challenging as quite often our ability to think about 'gender' as independent of 'sex' is not common. The influences and interplay of how sex (biological) and gender (social) affect mental health and illness requires consideration. Critical realism suggests a shared ontology and epistemology for the natural and social sciences. While much of the debate surrounding gender is guided within a constructivist discourse, an exploration of the concept 'gender' is reflected on and some key realist propositions are considered for mental health research and practice. This is achieved through the works of some key realist theorists. Critical realism offers potential for research and practice in relation to gender and mental health because it facilitates changes in our understanding, while simultaneously, not discarding that which is already known. In so doing, it allows the biological (sex) and social (gender) domains of knowledge for mental health and illness to coexist, without either being reduced to or defined by the other. Arguably, greater depth and explanations for gender and mental health issues are presented within a realist metatheory.

  6. Exposure render: an interactive photo-realistic volume rendering framework.

    Directory of Open Access Journals (Sweden)

    Thomas Kroes

    Full Text Available The field of volume visualization has undergone rapid development during the past years, both due to advances in suitable computing hardware and due to the increasing availability of large volume datasets. Recent work has focused on increasing the visual realism in Direct Volume Rendering (DVR by integrating a number of visually plausible but often effect-specific rendering techniques, for instance modeling of light occlusion and depth of field. Besides yielding more attractive renderings, especially the more realistic lighting has a positive effect on perceptual tasks. Although these new rendering techniques yield impressive results, they exhibit limitations in terms of their exibility and their performance. Monte Carlo ray tracing (MCRT, coupled with physically based light transport, is the de-facto standard for synthesizing highly realistic images in the graphics domain, although usually not from volumetric data. Due to the stochastic sampling of MCRT algorithms, numerous effects can be achieved in a relatively straight-forward fashion. For this reason, we have developed a practical framework that applies MCRT techniques also to direct volume rendering (DVR. With this work, we demonstrate that a host of realistic effects, including physically based lighting, can be simulated in a generic and flexible fashion, leading to interactive DVR with improved realism. In the hope that this improved approach to DVR will see more use in practice, we have made available our framework under a permissive open source license.

  7. Behaviorly realistic simulations of stock market traders with a soul

    Science.gov (United States)

    Solomon, Sorin

    1999-09-01

    The price fluctuations of the stocks in the financial markets are the result of the individual operations by many individual investors. However for many decades the financial theory did not use directly this “microscopic representation” of the markets. The main difficulties preventing this approach were solved recently with the advent of modern computer technology: - massive detailed data on the individual market operations became available; - “microscopic simulations” of the stock markets in terms of their individual participating agents allow very realistic treatment of the problem. By taking advantage of the modern computer processing and simulation techniques, we are now able to confront real market data with the results of simulating “microscopic” realistic models of the markets. These models have the potential to include and study the effects on the market of any desired feature in the investors behavior: departures from rationality, herding effects, heterogeneous investor-specific trading strategies. We propose to use the comparison of computer simulations of microscopic models with the actual market data in order to validate and enhance the knowledge on the financial behavior of individuals. Moreover we hope to explain, understand (and may be predict and control) macroscopic market dynamical features (e.g., cycles of booms and crashes, investors wealth distribution, market returns probability distribution etc.) based on realistic models using this knowledge.

  8. Towards Performance Evaluation of Cognitive Radio Network in Realistic Environment

    Directory of Open Access Journals (Sweden)

    Vivek Kukreja

    2013-11-01

    Full Text Available The scarcity of free spectrum compels us to look for alternatives for ever increasing wireless applications. Cognitive Radios (CR is one such alternative that can solve this problem. The network nodes having CR capability is termed as Cognitive Radio Network (CRN. To have communication in CRN a routing protocol is required. The primary goal of which is to provide a route from source to destination. Various routing protocols have been proposed and tested in idealistic environment using simulation software such as NS-2 and QualNet. This paper is an effort in the same direction but the efficacy is evaluated in realistic conditions by designing a simulator in MATLAB-7. To make the network scenario realistic obstacles of different shapes, type, sizes and numbers have been introduced. In addition to that the shape of the periphery is also varied to find the impact of it on routing protocols. From the results it is observed that the outcomes in the realistic and idealistic vary significantly. The reason for the same has also been discussed in this paper.

  9. Fast Rendering of Realistic Virtual Character in Game Scene

    Directory of Open Access Journals (Sweden)

    Mengzhao Yang

    2013-07-01

    Full Text Available Human skin is made up of multiple translucent layers and rendering of skin appearance usually acquire complex modeling and massive calculation. In some practical applications such as 3D game development, we not only approximate the realistic looking skin but also develop efficient method to implement easily for meeting needs of real-time rendering. In this study, we solve the problem of wrap lighting and introduce a surface details approximation method to give realistic rendering of virtual character. Our method considers that different thicknesses of geometry on the skin surface can result in different scattering degree of incident light and so pre-calculate the diffuse falloff into a look-up texture. Also, we notice that scattering is strongly color dependent and small bumps are common on the skin surface and so pre-soften the finer details on the skin surface according to the R/G/B channel. At last, we linearly interpolate the diffuse lighting with different scattering degree from the look-up texture sampled with the curvature and NdotL. Experiment results show that the proposed approach yields realistic virtual character and obtains high frames per second in real-time rendering.

  10. Modeling short-term dynamics and variability for realistic interactive facial animation.

    Science.gov (United States)

    Stoiber, Nicolas; Breton, Gaspard; Seguier, Renaud

    2010-01-01

    Modern modeling and rendering techniques have produced nearly photorealistic face models, but truly expressive digital faces also require natural-looking movements. Virtual characters in today's applications often display unrealistic facial expressions. Indeed, facial animation with traditional schemes such as keyframing and motion capture demands expertise. Moreover, the traditional schemes aren't adapted to interactive applications that require the real-time generation of context-dependent movements. A new animation system produces realistic expressive facial motion at interactive speed. The system relies on a set of motion models controlling facial-expression dynamics. The models are fitted on captured motion data and therefore retain the dynamic signature of human facial expressions. They also contain a nondeterministic component that ensures the variety of the long-term visual behavior. This system can efficiently animate any synthetic face. The video illustrates interactive use of a system that generates facial-animation sequences.

  11. The Exploration Connection

    Science.gov (United States)

    Anbar, A. D.; Elkins-Tanton, L. T.; Klug Boonstra, S.; Ben-Naim, D.

    2016-12-01

    In the past decade, advances in scientific visualization and public data access transformed science outreach and communication. At the same time, the development of adaptive, personalized online learning platforms began to transform education. These revolutions are advancing rapidly, but largely separately: spectacular visualizations have found only limited use in formal instruction, while online learning experiences do not often effectively integrate the cutting edge of visualization and accessible data. With support from NASA SMD, we are developing a new type of learning experience that brings these revolutions together, centered on space science, for the purpose of improving science literacy at societal scale. In these experiences, learners develop and apply authentic scientific reasoning skills to explore, test, and discover the science of our Solar System. These experiences embed state-of-the-art, authentic data and 3D visualization within purpose-built interactive simulations. These simulations are, in turn, embedded in standards-aligned, gamefully designed learning experiences developed using the Smart Sparrow e-learning platform. The platform enables interactive feedback and adaptive learning pathways, and provides rich analytics about learner interaction from large-scale deployments that can guide rapid improvement cycles. In the first of these learning experiences, centered on the "small worlds" of the Solar System and aimed at informal settings, learners explore the motions of different objects in the sky to discover the locations of asteroids, Near Earth Objects, and Kuiper Belt Objects, in relation to the planets. Exploration takes place in a visually rich, interactive environment built on a 3D graphics engine and realistic physics model. Learners make observations, and develop and test their conceptual understanding of these observations, via a learning process that is guided by adaptive feedback. The experience is motivated by an "astrocaching

  12. Adaptation and applications of a realistic digital phantom based on patient lung tumor trajectories

    Science.gov (United States)

    Mishra, Pankaj; St. James, Sara; Segars, W Paul; Berbeco, Ross I; Lewis, John H

    2012-01-01

    Digital phantoms continue to play a significant role in modeling and characterizing medical imaging. The currently available XCAT phantom incorporates both the flexibility of mathematical phantoms and the realistic nature of voxelized phantoms. This phantom generates images based on a regular breathing pattern and can include arbitrary lung tumor trajectories. In this work, we present an algorithm that modifies the current XCAT phantom to generate 4D imaging data based on irregular breathing. First, a parameter is added to the existing XCAT phantom to include any arbitrary tumor motion. This modification introduces the desired tumor motion but, comes at the cost of decoupled diaphragm, chest wall and lung motion. To remedy this problem diaphragm and chest wall motion is first modified based on initial tumor location and then input to the XCAT phantom. This generates a phantom with synchronized respiratory motion. Mapping of tumor motion trajectories to diaphragm and chest wall motion is done by adaptively calculating a scale factor based on tumor to lung contour distance. The distance is calculated by projecting the initial tumor location to lung edge contours characterized by quadratic polynomials. Data from 10 patients were used to evaluate the accuracy between actual independent tumor location and the location obtained from the modified XCAT phantom. The rmse and standard deviations for 10 patients in x, y, and z directions are: (0.29 ± 0.04, 0.54 ± 0.17, and 0.39 ± 0.06) mm. To demonstrate the utility of the phantom, we use the new phantom to simulate a 4DCT acquisition as well as a recently published method for phase sorting. The modified XCAT phantom can be used to generate more realistic imaging data for enhanced testing of algorithms for CT reconstruction, tumor tracking, and dose reconstruction. PMID:22595980

  13. A realistic evaluation: the case of protocol-based care

    Science.gov (United States)

    2010-01-01

    Background 'Protocol based care' was envisioned by policy makers as a mechanism for delivering on the service improvement agenda in England. Realistic evaluation is an increasingly popular approach, but few published examples exist, particularly in implementation research. To fill this gap, within this paper we describe the application of a realistic evaluation approach to the study of protocol-based care, whilst sharing findings of relevance about standardising care through the use of protocols, guidelines, and pathways. Methods Situated between positivism and relativism, realistic evaluation is concerned with the identification of underlying causal mechanisms, how they work, and under what conditions. Fundamentally it focuses attention on finding out what works, for whom, how, and in what circumstances. Results In this research, we were interested in understanding the relationships between the type and nature of particular approaches to protocol-based care (mechanisms), within different clinical settings (context), and what impacts this resulted in (outcomes). An evidence review using the principles of realist synthesis resulted in a number of propositions, i.e., context, mechanism, and outcome threads (CMOs). These propositions were then 'tested' through multiple case studies, using multiple methods including non-participant observation, interviews, and document analysis through an iterative analysis process. The initial propositions (conjectured CMOs) only partially corresponded to the findings that emerged during analysis. From the iterative analysis process of scrutinising mechanisms, context, and outcomes we were able to draw out some theoretically generalisable features about what works, for whom, how, and what circumstances in relation to the use of standardised care approaches (refined CMOs). Conclusions As one of the first studies to apply realistic evaluation in implementation research, it was a good fit, particularly given the growing emphasis on

  14. Asymptotically hyperbolic connections

    CERN Document Server

    Fine, Joel; Krasnov, Kirill; Scarinci, Carlos

    2015-01-01

    General Relativity in 4 dimensions can be equivalently described as a dynamical theory of SO(3)-connections rather than metrics. We introduce the notion of asymptotically hyperbolic connections, and work out an analog of the Fefferman-Graham expansion in the language of connections. As in the metric setup, one can solve the arising "evolution" equations order by order in the expansion in powers of the radial coordinate. The solution in the connection setting is arguably simpler, and very straightforward algebraic manipulations allow one to see how the obstruction appears at third order in the expansion. Another interesting feature of the connection formulation is that the "counter terms" required in the computation of the renormalised volume all combine into the Chern-Simons functional of the restriction of the connection to the boundary. As the Chern-Simons invariant is only defined modulo large gauge transformations, the requirement that the path integral over asymptotically hyperbolic connections is well-d...

  15. A developmental approach to predicting neuronal connectivity from small biological datasets: a gradient-based neuron growth model.

    Science.gov (United States)

    Borisyuk, Roman; Al Azad, Abul Kalam; Conte, Deborah; Roberts, Alan; Soffe, Stephen R

    2014-01-01

    Relating structure and function of neuronal circuits is a challenging problem. It requires demonstrating how dynamical patterns of spiking activity lead to functions like cognitive behaviour and identifying the neurons and connections that lead to appropriate activity of a circuit. We apply a "developmental approach" to define the connectome of a simple nervous system, where connections between neurons are not prescribed but appear as a result of neuron growth. A gradient based mathematical model of two-dimensional axon growth from rows of undifferentiated neurons is derived for the different types of neurons in the brainstem and spinal cord of young tadpoles of the frog Xenopus. Model parameters define a two-dimensional CNS growth environment with three gradient cues and the specific responsiveness of the axons of each neuron type to these cues. The model is described by a nonlinear system of three difference equations; it includes a random variable, and takes specific neuron characteristics into account. Anatomical measurements are first used to position cell bodies in rows and define axon origins. Then a generalization procedure allows information on the axons of individual neurons from small anatomical datasets to be used to generate larger artificial datasets. To specify parameters in the axon growth model we use a stochastic optimization procedure, derive a cost function and find the optimal parameters for each type of neuron. Our biologically realistic model of axon growth starts from axon outgrowth from the cell body and generates multiple axons for each different neuron type with statistical properties matching those of real axons. We illustrate how the axon growth model works for neurons with axons which grow to the same and the opposite side of the CNS. We then show how, by adding a simple specification for dendrite morphology, our model "developmental approach" allows us to generate biologically-realistic connectomes.

  16. A developmental approach to predicting neuronal connectivity from small biological datasets: a gradient-based neuron growth model.

    Directory of Open Access Journals (Sweden)

    Roman Borisyuk

    Full Text Available Relating structure and function of neuronal circuits is a challenging problem. It requires demonstrating how dynamical patterns of spiking activity lead to functions like cognitive behaviour and identifying the neurons and connections that lead to appropriate activity of a circuit. We apply a "developmental approach" to define the connectome of a simple nervous system, where connections between neurons are not prescribed but appear as a result of neuron growth. A gradient based mathematical model of two-dimensional axon growth from rows of undifferentiated neurons is derived for the different types of neurons in the brainstem and spinal cord of young tadpoles of the frog Xenopus. Model parameters define a two-dimensional CNS growth environment with three gradient cues and the specific responsiveness of the axons of each neuron type to these cues. The model is described by a nonlinear system of three difference equations; it includes a random variable, and takes specific neuron characteristics into account. Anatomical measurements are first used to position cell bodies in rows and define axon origins. Then a generalization procedure allows information on the axons of individual neurons from small anatomical datasets to be used to generate larger artificial datasets. To specify parameters in the axon growth model we use a stochastic optimization procedure, derive a cost function and find the optimal parameters for each type of neuron. Our biologically realistic model of axon growth starts from axon outgrowth from the cell body and generates multiple axons for each different neuron type with statistical properties matching those of real axons. We illustrate how the axon growth model works for neurons with axons which grow to the same and the opposite side of the CNS. We then show how, by adding a simple specification for dendrite morphology, our model "developmental approach" allows us to generate biologically-realistic connectomes.

  17. "It's Just Not Very Realistic": Perceptions of Media Among Pregnant and Postpartum Women.

    Science.gov (United States)

    Liechty, Toni; Coyne, Sarah M; Collier, Kevin M; Sharp, Aubrey D

    2017-05-03

    Although research has documented a connection between media and body image for women, little research has explored this connection among pregnant or postpartum women. The purpose of this study was to explore women's perceptions of media and body image during the perinatal period. Fredrickson's objectification theory provided a theoretical framework for the study. Data collection involved semi-structured in-depth interviews with 50 pregnant or postpartum women in which they were asked to describe their perceptions of media depictions of pregnant or postpartum women and its impact on their body image. Interviews were audio-recorded, transcribed verbatim, and analyzed thematically. Four major themes emerged: (1) participants questioned the realism of media depictions of pregnant and postpartum women, (2) participants described complex reactions to media messages including negative impacts on body image and strategies for mitigating negative impacts, (3) participants desired changes in media messages to be more realistic and to depict a more complex portrayal of the life stage, and (4) participants discussed the unique and complex role of social media including both negative and positive impacts. Implications of the findings for pregnant and postpartum women, communication scholars, and healthcare professionals are discussed.

  18. Development of a realistic in vivo bone metastasis model of human renal cell carcinoma.

    Science.gov (United States)

    Valta, Maija P; Zhao, Hongjuan; Ingels, Alexandre; Thong, Alan E; Nolley, Rosalie; Saar, Matthias; Peehl, Donna M

    2014-06-01

    About one-third of patients with advanced renal cell carcinoma (RCC) have bone metastases. The incidence of RCC is increasing and bone metastatic RCC merits greater focus. Realistic preclinical bone metastasis models of RCC are lacking, hampering the development of effective therapies. We developed a realistic in vivo bone metastasis model of human RCC by implanting precision-cut tissue slices under the renal capsule of immunodeficient mice. The presence of disseminated cells in bone marrow of tissue slice graft (TSG)-bearing mice was screened by human-specific polymerase chain reaction and confirmed by immunohistology using human-specific antibody. Disseminated tumor cells in bone marrow of TSG-bearing mice derived from three of seven RCC patients were detected as early as 1 month after tissue implantation at a high frequency with close resemblance to parent tumors (e.g., CAIX expression and high vascularity). The metastatic patterns of TSGs correlated with disease progression in patients. In addition, TSGs retained capacity to metastasize to bone at high frequency after serial passaging and cryopreservation. Moreover, bone metastases in mice responded to Temsirolimus treatment. Intratibial injections of single cells generated from TSGs showed 100 % engraftment and produced X-ray-visible tumors as early as 3 weeks after cancer cell inoculation. Micro-computed tomography (μCT) and histological analysis revealed osteolytic characteristics of these lesions. Our results demonstrated that orthotopic RCC TSGs have potential to develop bone metastases that respond to standard therapy. This first reported primary RCC bone metastasis model provides a realistic setting to test therapeutics to prevent or treat bone metastases in RCC.

  19. Complete methodology on generating realistic wind speed profiles based on measurements

    DEFF Research Database (Denmark)

    Gavriluta, Catalin; Spataru, Sergiu; Mosincat, Ioan

    2012-01-01

    The wind speed represents the main exogenous signal applied to a Wind Energy Conversion System (WECS) and determines its behavior. The erratic variation of the wind speed, highly dependent on the given site and on the atmospheric conditions, makes the wind speed quite difficult to model. Moreover...

  20. Temperature simulations in tissue with a realistic computer generated vessel network.

    Science.gov (United States)

    Van Leeuwen, G M; Kotte, A N; Raaymakers, B W; Lagendijk, J J

    2000-04-01

    The practical use of a discrete vessel thermal model for hyperthermia treatment planning requires a number of choices with respect to the unknown part of the patient's vasculature. This work presents a study of the thermal effects of blood flow in a simple tissue geometry with a detailed artificial vessel network. The simulations presented here demonstrate that an incomplete discrete description of the detailed network results in a better prediction of the temperature distribution than is obtained using the conventional bio-heatsink equation. Therefore, efforts to obtain information on the positions of the large vessels in an individual hyperthermia patient will be rewarded with a more accurate prediction of the temperature distribution.

  1. Generating Geospatially Realistic Driving Patterns Derived From Clustering Analysis Of Real EV Driving Data

    DEFF Research Database (Denmark)

    Pedersen, Anders Bro; Aabrandt, Andreas; Østergaard, Jacob

    2014-01-01

    scales, which calls for a statistically correct, yet flexible model. This paper describes a method for modelling EV, based on non-categorized data, which takes into account the plug in locations of the vehicles. By using clustering analysis to extrapolate and classify the primary locations where...

  2. Generation of higher order Gauss-Laguerre modes in single-pass 2nd harmonic generation

    DEFF Research Database (Denmark)

    Buchhave, Preben; Tidemand-Lichtenberg, Peter

    2008-01-01

    We present a realistic method for dynamic simulation of the development of higher order modes in second harmonic generation. The deformation of the wave fronts due to the nonlinear interaction is expressed by expansion in higher order Gauss-Laguerre modes.......We present a realistic method for dynamic simulation of the development of higher order modes in second harmonic generation. The deformation of the wave fronts due to the nonlinear interaction is expressed by expansion in higher order Gauss-Laguerre modes....

  3. Using computational models to relate structural and functional brain connectivity.

    Science.gov (United States)

    Hlinka, Jaroslav; Coombes, Stephen

    2012-07-01

    Modern imaging methods allow a non-invasive assessment of both structural and functional brain connectivity. This has lead to the identification of disease-related alterations affecting functional connectivity. The mechanism of how such alterations in functional connectivity arise in a structured network of interacting neural populations is as yet poorly understood. Here we use a modeling approach to explore the way in which this can arise and to highlight the important role that local population dynamics can have in shaping emergent spatial functional connectivity patterns. The local dynamics for a neural population is taken to be of the Wilson-Cowan type, whilst the structural connectivity patterns used, describing long-range anatomical connections, cover both realistic scenarios (from the CoComac database) and idealized ones that allow for more detailed theoretical study. We have calculated graph-theoretic measures of functional network topology from numerical simulations of model networks. The effect of the form of local dynamics on the observed network state is quantified by examining the correlation between structural and functional connectivity. We document a profound and systematic dependence of the simulated functional connectivity patterns on the parameters controlling the dynamics. Importantly, we show that a weakly coupled oscillator theory explaining these correlations and their variation across parameter space can be developed. This theoretical development provides a novel way to characterize the mechanisms for the breakdown of functional connectivity in diseases through changes in local dynamics.

  4. 并网光伏发电系统在污水处理厂中的应用%Application of Grid-connected Photovoltaic Generation System in Sewage Treatment Factory

    Institute of Scientific and Technical Information of China (English)

    言穆昀

    2015-01-01

    This paper introduced the design of grid-connected photovoltaic power in Beijing sewage treatment factory.By using the effective space above the structure,the installation of a solar cell panel roof was carried out,so the nonadjustable focus grid-connected photovoltaic power station was built.The grid-connected photovoltaic power meets the electricity demand of sewage treatment factory during the day,and to a certain extent controls the evaporation capacity and the temperature of the sewage pool,to improve the sewage treatment capacity.%介绍了北京市郊某污水处理厂并网光伏发电系统的设计。利用污水处理厂构筑物上方的有效空间,加装带有太阳能电池板的顶棚,建成不可调型集中并网光伏发电站,既满足了污水处理厂白天用电高峰期时的电力供应,又在一定程度上控制了污水池的蒸发量和温度,提高了污水处理能力。

  5. Eccentric connectivity index

    CERN Document Server

    Ilić, Aleksandar

    2011-01-01

    The eccentric connectivity index $\\xi^c$ is a novel distance--based molecular structure descriptor that was recently used for mathematical modeling of biological activities of diverse nature. It is defined as $\\xi^c (G) = \\sum_{v \\in V (G)} deg (v) \\cdot \\epsilon (v)$\\,, where $deg (v)$ and $\\epsilon (v)$ denote the vertex degree and eccentricity of $v$\\,, respectively. We survey some mathematical properties of this index and furthermore support the use of eccentric connectivity index as topological structure descriptor. We present the extremal trees and unicyclic graphs with maximum and minimum eccentric connectivity index subject to the certain graph constraints. Sharp lower and asymptotic upper bound for all graphs are given and various connections with other important graph invariants are established. In addition, we present explicit formulae for the values of eccentric connectivity index for several families of composite graphs and designed a linear algorithm for calculating the eccentric connectivity in...

  6. On eccentric connectivity index

    CERN Document Server

    Zhou, Bo

    2010-01-01

    The eccentric connectivity index, proposed by Sharma, Goswami and Madan, has been employed successfully for the development of numerous mathematical models for the prediction of biological activities of diverse nature. We now report mathematical properties of the eccentric connectivity index. We establish various lower and upper bounds for the eccentric connectivity index in terms of other graph invariants including the number of vertices, the number of edges, the degree distance and the first Zagreb index. We determine the n-vertex trees of diameter with the minimum eccentric connectivity index, and the n-vertex trees of pendent vertices, with the maximum eccentric connectivity index. We also determine the n-vertex trees with respectively the minimum, second-minimum and third-minimum, and the maximum, second-maximum and third-maximum eccentric connectivity indices for

  7. Using digital colour to increase the realistic appearance of SEM micrographs of bloodstains.

    Science.gov (United States)

    Hortolà, Policarp

    2010-10-01

    Although in the scientific-research literature the micrographs from scanning electron microscopes (SEMs) are usually displayed in greyscale, the potential of colour resources provided by the SEM-coupled image-acquiring systems and, subsidiarily, by image-manipulation free softwares deserves be explored as a tool for colouring SEM micrographs of bloodstains. After acquiring greyscale SEM micrographs of a (dark red to the naked eye) human blood smear on grey chert, they were manually obtained in red tone using both the SEM-coupled image-acquiring system and an image-manipulation free software, as well as they were automatically generated in thermal tone using the SEM-coupled system. Red images obtained by the SEM-coupled system demonstrated lower visual-discrimination capability than the other coloured images, whereas those in red generated by the free software rendered better magnitude of scopic information than the red images generated by the SEM-coupled system. Thermal-tone images, although were further from the real sample colour than the red ones, not only increased their realistic appearance over the greyscale images, but also yielded the best visual-discrimination capability among all the coloured SEM micrographs, and fairly enhanced the relief effect of the SEM micrographs over both the greyscale and the red images. The application of digital colour by means of the facilities provided by an SEM-coupled image-acquiring system or, when required, by an image-manipulation free software provides a user-friendly, quick and inexpensive way of obtaining coloured SEM micrographs of bloodstains, avoiding to do sophisticated, time-consuming colouring procedures. Although this work was focused on bloodstains, well probably other monochromatic or quasi-monochromatic samples are also susceptible of increasing their realistic appearance by colouring them using the simple methods utilized in this study.

  8. Institutions for Asian Connectivity

    OpenAIRE

    Bhattacharyay, Biswa

    2010-01-01

    To make Asia more economically sustainable and resilient against external shocks, regional economies need to be rebalanced toward regional demand- and trade-driven growth through increased regional connectivity. The effectiveness of connectivity depends on the quality of hard and soft infrastructure. Of particular importance in terms of soft infrastructure which makes hard infrastructure work are the facilitating institutions that support connectivity through appropriate policies, reforms, sy...

  9. Handbook of networking & connectivity

    CERN Document Server

    McClain, Gary R

    1994-01-01

    Handbook of Networking & Connectivity focuses on connectivity standards in use, including hardware and software options. The book serves as a guide for solving specific problems that arise in designing and maintaining organizational networks.The selection first tackles open systems interconnection, guide to digital communications, and implementing TCP/IP in an SNA environment. Discussions focus on elimination of the SNA backbone, routing SNA over internets, connectionless versus connection-oriented networks, internet concepts, application program interfaces, basic principles of layering, proto

  10. Scaling up complex interventions: insights from a realist synthesis.

    Science.gov (United States)

    Willis, Cameron D; Riley, Barbara L; Stockton, Lisa; Abramowicz, Aneta; Zummach, Dana; Wong, Geoff; Robinson, Kerry L; Best, Allan

    2016-12-19

    Preventing chronic diseases, such as cancer, cardiovascular disease and diabetes, requires complex interventions, involving multi-component and multi-level efforts that are tailored to the contexts in which they are delivered. Despite an increasing number of complex interventions in public health, many fail to be 'scaled up'. This study aimed to increase understanding of how and under what conditions complex public health interventions may be scaled up to benefit more people and populations.A realist synthesis was conducted and discussed at an in-person workshop involving practitioners responsible for scaling up activities. Realist approaches view causality through the linkages between changes in contexts (C) that activate mechanisms (M), leading to specific outcomes (O) (CMO configurations). To focus this review, three cases of complex interventions that had been successfully scaled up were included: Vibrant Communities, Youth Build USA and Pathways to Education. A search strategy of published and grey literature related to each case was developed, involving searches of relevant databases and nominations from experts. Data extracted from included documents were classified according to CMO configurations within strategic themes. Findings were compared and contrasted with guidance from diffusion theory, and interpreted with knowledge users to identify practical implications and potential directions for future research.Four core mechanisms were identified, namely awareness, commitment, confidence and trust. These mechanisms were activated within two broad scaling up strategies, those of renewing and regenerating, and documenting success. Within each strategy, specific actions to change contexts included building partnerships, conducting evaluations, engaging political support and adapting funding models. These modified contexts triggered the identified mechanisms, leading to a range of scaling up outcomes, such as commitment of new communities, changes in relevant

  11. A continuous family of realistic Susy SU(5) GUTs

    Science.gov (United States)

    Bajc, Borut

    2016-06-01

    It is shown that the minimal renormalizable supersymmetric SU(5) is still realistic providing the supersymmetric scale is at least few tens of TeV or large R-parity violating terms are considered. In the first case the vacuum is metastable, and different consistency constraints can give a bounded allowed region in the tan β - msusy plane. In the second case the mass eigenstate electron (down quark) is a linear combination of the original electron (down quark) and Higgsino (heavy colour triplet), and the mass ratio of bino and wino is determined. Both limits lead to light gravitino dark matter.

  12. ROC Analysis and a Realistic Model of Heart Rate Variability

    CERN Document Server

    Thurner, S; Teich, M C; Thurner, Stefan; Feurstein, Markus C.; Teich, Malvin C.

    1998-01-01

    We have carried out a pilot study on a standard collection of electrocardiograms from patients who suffer from congestive heart failure, and subjects without cardiac pathology, using receiver-operating-characteristic (ROC) analysis. The scale-dependent wavelet-coefficient standard deviation superior to two commonly used measures of cardiac dysfunction when the two classes of patients cannot be completely separated. A jittered integrate-and-fire model with a fractal Gaussian-noise kernel provides a realistic simulation of heartbeat sequences for both heart-failure patients and normal subjects.

  13. Recovering the quantum formalism from physically realist axioms.

    Science.gov (United States)

    Auffèves, Alexia; Grangier, Philippe

    2017-03-03

    We present a heuristic derivation of Born's rule and unitary transforms in Quantum Mechanics, from a simple set of axioms built upon a physical phenomenology of quantization. This approach naturally leads to the usual quantum formalism, within a new realistic conceptual framework that is discussed in details. Physically, the structure of Quantum Mechanics appears as a result of the interplay between the quantized number of "modalities" accessible to a quantum system, and the continuum of "contexts" that are required to define these modalities. Mathematically, the Hilbert space structure appears as a consequence of a specific "extra-contextuality" of modalities, closely related to the hypothesis of Gleason's theorem, and consistent with its conclusions.

  14. Centralized Cooperative Positioning and Tracking with Realistic Communications Constraints

    DEFF Research Database (Denmark)

    Mensing, Christian; Nielsen, Jimmy Jessen

    2010-01-01

    In this paper, we investigate the performance of centralized cooperative positioning algorithms. Compared to traditional positioning algorithms which solely exploit ranging information from anchor nodes, cooperative positioning additionally uses measurements from peer-to-peer links between...... on the overall performance will be assessed. As we are considering a dynamic scenario, the cooperative positioning algorithms are based on extended Kalman filtering for position estimation and tracking. Simulation results for ultra-wideband based ranging information and WLAN based communications infrastructure...... show the benefits of cooperative position and tracking for realistic measurement and mobility models....

  15. Assumptions behind size-based ecosystem models are realistic

    DEFF Research Database (Denmark)

    Andersen, Ken Haste; Blanchard, Julia L.; Fulton, Elizabeth A.;

    2016-01-01

    A recent publication about balanced harvesting (Froese et al., ICES Journal of Marine Science; doi:10.1093/icesjms/fsv122) contains several erroneous statements about size-spectrum models. We refute the statements by showing that the assumptions pertaining to size-spectrum models discussed...... by Froese et al. are realistic and consistent. We further show that the assumption about density-dependence being described by a stock recruitment relationship is responsible for determining whether a peak in the cohort biomass of a population occurs late or early in life. Finally, we argue...

  16. Mode-Coupling in Realistic Rotating Gravitational Collapse

    CERN Document Server

    Hod, S

    2000-01-01

    We analyze the mode-coupling phenomena in realistic rotating gravitational collapse. Physically, this phenomena is caused by the dragging of reference frames, due to the black-hole (or star's) rotation. It is shown that different modes become coupled during the rotating collapse. As a consequence, the asymptotic late-time tails are dominated by modes which, in general, have an angular distribution different from the original one. We show that a rotating Kerr black hole becomes ``bald'' slower than a spherically-symmetric Schwarzschild black hole. This paper considers gravitational, electromagnetic and neutrino fields propagating on a Kerr background.

  17. Ultra-Reliable Communications in Failure-Prone Realistic Networks

    DEFF Research Database (Denmark)

    Gerardino, Guillermo Andrés Pocovi; Lauridsen, Mads; Alvarez, Beatriz Soret

    2016-01-01

    We investigate the potential of different diversity and interference management techniques to achieve the required downlink SINR outage probability for ultra-reliable communications. The evaluation is performed in a realistic network deployment based on site-specific data from a European capital....... Micro and macroscopic diversity techniques are proved to be important enablers of ultra-reliable communications. Particularly, it is shown how a 4x4 MIMO scheme with three orders of macroscopic diversity can achieve the required SINR outage performance. Smaller gains are obtained from interference...

  18. Dynamic Enhanced Inter-Cell Interference Coordination for Realistic Networks

    DEFF Research Database (Denmark)

    Pedersen, Klaus I.; Alvarez, Beatriz Soret; Barcos, Sonia;

    2016-01-01

    Enhanced Inter-Cell Interference Coordination (eICIC) is a key ingredient to boost the performance of co-channel Heterogeneous Networks (HetNets). eICIC encompasses two main techniques: Almost Blank Subframes (ABS), during which the macro cell remains silent to reduce the interference, and biased...... and an opportunistic approach exploiting the varying cell conditions. Moreover, an autonomous fast distributed muting algorithm is presented, which is simple, robust, and well suited for irregular network deployments. Performance results for realistic network deployments show that the traditional semi-static e...

  19. Can realistic nuclear interactions tolerate a resonant tetraneutron ?

    CERN Document Server

    Lazauskas, R

    2005-01-01

    The possible existence of four-neutron resonances close to the physical energy region is explored. Faddeev-Yakubovsky equations have been solved in configuration space using realistic nucleon-nucleon interaction models. Complex Scaling and Analytical Continuation in the Coupling Constant methods were used to follow the resonance pole trajectories, which emerge out of artificially bound tetraneutron states. The final pole positions for four-neutron states lie in the third energy quadrant with negative real energy parts and should thus not be physically observable.

  20. The KM phase in semi-realistic heterotic orbifold models

    Energy Technology Data Exchange (ETDEWEB)

    Giedt, Joel

    2000-07-05

    In string-inspired semi-realistic heterotic orbifolds models with an anomalous U(1){sub X},a nonzero Kobayashi-Masakawa (KM) phase is shown to arise generically from the expectation values of complex scalar fields, which appear in nonrenormalizable quark mass couplings. Modular covariant nonrenormalizable superpotential couplings are constructed. A toy Z{sub 3} orbifold model is analyzed in some detail. Modular symmetries and orbifold selection rules are taken into account and do not lead to a cancellation of the KM phase. We also discuss attempts to obtain the KM phase solely from renormalizable interactions.