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Sample records for modelling approaches electronic

  1. Modeling Electronic Circular Dichroism within the Polarizable Embedding Approach

    DEFF Research Database (Denmark)

    Nørby, Morten S; Olsen, Jógvan Magnus Haugaard; Steinmann, Casper

    2017-01-01

    We present a systematic investigation of the key components needed to model single chromophore electronic circular dichroism (ECD) within the polarizable embedding (PE) approach. By relying on accurate forms of the embedding potential, where especially the inclusion of local field effects...... are in focus, we show that qualitative agreement between rotatory strength parameters calculated by full quantum mechanical calculations and the more efficient embedding calculations can be obtained. An important aspect in the computation of reliable absorption parameters is the need for conformational...

  2. Electron correlations in narrow energy bands: modified polar model approach

    Directory of Open Access Journals (Sweden)

    L. Didukh

    2008-09-01

    Full Text Available The electron correlations in narrow energy bands are examined within the framework of the modified form of polar model. This model permits to analyze the effect of strong Coulomb correlation, inter-atomic exchange and correlated hopping of electrons and explain some peculiarities of the properties of narrow-band materials, namely the metal-insulator transition with an increase of temperature, nonlinear concentration dependence of Curie temperature and peculiarities of transport properties of electronic subsystem. Using a variant of generalized Hartree-Fock approximation, the single-electron Green's function and quasi-particle energy spectrum of the model are calculated. Metal-insulator transition with the change of temperature is investigated in a system with correlated hopping. Processes of ferromagnetic ordering stabilization in the system with various forms of electronic DOS are studied. The static conductivity and effective spin-dependent masses of current carriers are calculated as a function of electron concentration at various DOS forms. The correlated hopping is shown to cause the electron-hole asymmetry of transport and ferromagnetic properties of narrow band materials.

  3. MODELING OF QUALITY MANAGEMENT SYSTEM FOR ELECTRONIC LEARNING RESOURCES: THE INTEGRATED AND DIFFERENTIATED APPROACHES

    Directory of Open Access Journals (Sweden)

    H. M. Kravtsov

    2012-03-01

    Full Text Available Abstract. Results on modeling of quality management system of electronic information resources on the basis of the analysis of its elements functioning with use of the integrated and differentiated approaches are presented. Application of such model is illustrated on an example of calculation and optimization of parameters of a quality management system at the organization of the co-ordinated work of services of monitoring, an estimation of quality and support of electronic learning resources.

  4. A graphical vector autoregressive modelling approach to the analysis of electronic diary data

    Directory of Open Access Journals (Sweden)

    Zipfel Stephan

    2010-04-01

    Full Text Available Abstract Background In recent years, electronic diaries are increasingly used in medical research and practice to investigate patients' processes and fluctuations in symptoms over time. To model dynamic dependence structures and feedback mechanisms between symptom-relevant variables, a multivariate time series method has to be applied. Methods We propose to analyse the temporal interrelationships among the variables by a structural modelling approach based on graphical vector autoregressive (VAR models. We give a comprehensive description of the underlying concepts and explain how the dependence structure can be recovered from electronic diary data by a search over suitable constrained (graphical VAR models. Results The graphical VAR approach is applied to the electronic diary data of 35 obese patients with and without binge eating disorder (BED. The dynamic relationships for the two subgroups between eating behaviour, depression, anxiety and eating control are visualized in two path diagrams. Results show that the two subgroups of obese patients with and without BED are distinguishable by the temporal patterns which influence their respective eating behaviours. Conclusion The use of the graphical VAR approach for the analysis of electronic diary data leads to a deeper insight into patient's dynamics and dependence structures. An increasing use of this modelling approach could lead to a better understanding of complex psychological and physiological mechanisms in different areas of medical care and research.

  5. Deducing Electronic Unit Internal Response During a Vibration Test Using a Lumped Parameter Modeling Approach

    Science.gov (United States)

    Van Dyke, Michael B.

    2014-01-01

    During random vibration testing of electronic boxes there is often a desire to know the dynamic response of certain internal printed wiring boards (PWBs) for the purpose of monitoring the response of sensitive hardware or for post-test forensic analysis in support of anomaly investigation. Due to restrictions on internally mounted accelerometers for most flight hardware there is usually no means to empirically observe the internal dynamics of the unit, so one must resort to crude and highly uncertain approximations. One common practice is to apply Miles Equation, which does not account for the coupled response of the board in the chassis, resulting in significant over- or under-prediction. This paper explores the application of simple multiple-degree-of-freedom lumped parameter modeling to predict the coupled random vibration response of the PWBs in their fundamental modes of vibration. A simple tool using this approach could be used during or following a random vibration test to interpret vibration test data from a single external chassis measurement to deduce internal board dynamics by means of a rapid correlation analysis. Such a tool might also be useful in early design stages as a supplemental analysis to a more detailed finite element analysis to quickly prototype and analyze the dynamics of various design iterations. After developing the theoretical basis, a lumped parameter modeling approach is applied to an electronic unit for which both external and internal test vibration response measurements are available for direct comparison. Reasonable correlation of the results demonstrates the potential viability of such an approach. Further development of the preliminary approach presented in this paper will involve correlation with detailed finite element models and additional relevant test data.

  6. Modeling a terminology-based electronic nursing record system: an object-oriented approach.

    Science.gov (United States)

    Park, Hyeoun-Ae; Cho, InSook; Byeun, NamSoo

    2007-10-01

    The aim of this study was to present our perspectives on healthcare information analysis at a conceptual level and the lessons learned from our experience with the development of a terminology-based enterprise electronic nursing record system - which was one of components in an EMR system at a tertiary teaching hospital in Korea - using an object-oriented system analysis and design concept. To ensure a systematic approach and effective collaboration, the department of nursing constituted a system modeling team comprising a project manager, systems analysts, user representatives, an object-oriented methodology expert, and healthcare informaticists (including the authors). A rational unified process (RUP) and the Unified Modeling Language were used as a development process and for modeling notation, respectively. From the scenario and RUP approach, user requirements were formulated into use case sets and the sequence of activities in the scenario was depicted in an activity diagram. The structure of the system was presented in a class diagram. This approach allowed us to identify clearly the structural and behavioral states and important factors of a terminology-based ENR system (e.g., business concerns and system design concerns) according to the viewpoints of both domain and technical experts.

  7. Electronics a systems approach

    CERN Document Server

    Storey, Neil

    2017-01-01

    Electronics plays a central role in our everyday lives. It is at the heart of almost all of today's essential technology, from mobile phones to computers and from cars to power stations. As such, all engineers, scientists and technologists need to have a fundamental understanding of this exciting subject, and for many this will just be the beginning. Now in its sixth edition, Electronics: A Systems Approach provides an outstanding introduction to this fast-moving and important field. Comprehensively revised and updated to cover the latest developments in the world of electronics, the text continues to use Neil Storey's established and well-respected systems approach. It introduces the basic concepts first before progressing to a more advanced analysis, enabling you to contextualise what a system is designed to achieve before tackling the intricacies of designing or analysing its various components with confidence. This book is accompanied by a website which contains over 100 video tutorials to help explain ke...

  8. Electronic Cigarettes and Indoor Air Quality: A Simple Approach to Modeling Potential Bystander Exposures to Nicotine

    Directory of Open Access Journals (Sweden)

    Stéphane Colard

    2014-12-01

    Full Text Available There has been rapid growth in the use of electronic cigarettes (“vaping” in Europe, North America and elsewhere. With such increased prevalence, there is currently a debate on whether the aerosol exhaled following the use of e-cigarettes has implications for the quality of air breathed by bystanders. Conducting chemical analysis of the indoor environment can be costly and resource intensive, limiting the number of studies which can be conducted. However, this can be modelled reasonably accurately based on empirical emissions data and using some basic assumptions. Here, we present a simplified model, based on physical principles, which considers aerosol propagation, dilution and extraction to determine the potential contribution of a single puff from an e-cigarette to indoor air. From this, it was then possible to simulate the cumulative effect of vaping over time. The model was applied to a virtual, but plausible, scenario considering an e-cigarette user and a non-user working in the same office space. The model was also used to reproduce published experimental studies and showed good agreement with the published values of indoor air nicotine concentration. With some additional refinements, such an approach may be a cost-effective and rapid way of assessing the potential exposure of bystanders to exhaled e-cigarette aerosol constituents.

  9. Development of an Electronic Portfolio System Success Model: An Information Systems Approach

    Science.gov (United States)

    Balaban, Igor; Mu, Enrique; Divjak, Blazenka

    2013-01-01

    This research has two main goals: to develop an instrument for assessing Electronic Portfolio (ePortfolio) success and to build a corresponding ePortfolio success model using DeLone and McLean's information systems success model as the theoretical framework. For this purpose, we developed an ePortfolio success measurement instrument and structural…

  10. Approaches to modelling irradiation-induced processes in transmission electron microscopy.

    Science.gov (United States)

    Skowron, Stephen T; Lebedeva, Irina V; Popov, Andrey M; Bichoutskaia, Elena

    2013-08-07

    The recent progress in high-resolution transmission electron microscopy (HRTEM) has given rise to the possibility of in situ observations of nanostructure transformations and chemical reactions induced by electron irradiation. In this article we briefly summarise experimental observations and discuss in detail atomistic modelling of irradiation-induced processes in HRTEM, as well as mechanisms of such processes recognised due to modelling. Accurate molecular dynamics (MD) techniques based on first principles or tight-binding models are employed in the analysis of single irradiation-induced events, and classical MD simulations are combined with a kinetic Monte Carlo algorithm to simulate continuous irradiation of nanomaterials. It has been shown that sulphur-terminated graphene nanoribbons are formed inside carbon nanotubes as a result of an irradiation-selective chemical reaction. The process of fullerene formation in HRTEM during continuous electron irradiation of a small graphene flake has been simulated, and mechanisms driving this transformation analysed.

  11. Predictive Modeling for Strongly Correlated f-electron Systems: A first-principles and database driven machine learning approach

    Science.gov (United States)

    Ahmed, Towfiq; Khair, Adnan; Abdullah, Mueen; Harper, Heike; Eriksson, Olle; Wills, John; Zhu, Jian-Xin; Balatsky, Alexander

    Data driven computational tools are being developed for theoretical understanding of electronic properties in f-electron based materials, e.g., Lanthanides and Actnides compounds. Here we show our preliminary work on Ce compounds. Due to a complex interplay among the hybridization of f-electrons to non-interacting conduction band, spin-orbit coupling, and strong coulomb repulsion of f-electrons, no model or first-principles based theory can fully explain all the structural and functional phases of f-electron systems. Motivated by the large need in predictive modeling of actinide compounds, we adopted a data-driven approach. We found negative correlation between the hybridization and atomic volume. Mutual information between these two features were also investigated. In order to extend our search space with more features and predictability of new compounds, we are currently developing electronic structure database. Our f-electron database will be potentially aided by machine learning (ML) algorithm to extract complex electronic, magnetic and structural properties in f-electron system, and thus, will open up new pathways for predictive capabilities and design principles of complex materials. NSEC, IMS at LANL.

  12. Modelling the experimental electron density: only the synergy of various approaches can tackle the new challenges

    Directory of Open Access Journals (Sweden)

    Piero Macchi

    2015-07-01

    Full Text Available Electron density is a fundamental quantity that enables understanding of the chemical bonding in a molecule or in a solid and the chemical/physical property of a material. Because electrons have a charge and a spin, two kinds of electron densities are available. Moreover, because electron distribution can be described in momentum or in position space, charge and spin density have two definitions and they can be observed through Bragg (for the position space or Compton (for the momentum space diffraction experiments, using X-rays (charge density or polarized neutrons (spin density. In recent years, we have witnessed many advances in this field, stimulated by the increased power of experimental techniques. However, an accurate modelling is still necessary to determine the desired functions from the acquired data. The improved accuracy of measurements and the possibility to combine information from different experimental techniques require even more flexibility of the models. In this short review, we analyse some of the most important topics that have emerged in the recent literature, especially the most thought-provoking at the recent IUCr general meeting in Montreal.

  13. 2D hybrid analysis: Approach for building three-dimensional atomic model by electron microscopy image matching.

    Science.gov (United States)

    Matsumoto, Atsushi; Miyazaki, Naoyuki; Takagi, Junichi; Iwasaki, Kenji

    2017-03-23

    In this study, we develop an approach termed "2D hybrid analysis" for building atomic models by image matching from electron microscopy (EM) images of biological molecules. The key advantage is that it is applicable to flexible molecules, which are difficult to analyze by 3DEM approach. In the proposed approach, first, a lot of atomic models with different conformations are built by computer simulation. Then, simulated EM images are built from each atomic model. Finally, they are compared with the experimental EM image. Two kinds of models are used as simulated EM images: the negative stain model and the simple projection model. Although the former is more realistic, the latter is adopted to perform faster computations. The use of the negative stain model enables decomposition of the averaged EM images into multiple projection images, each of which originated from a different conformation or orientation. We apply this approach to the EM images of integrin to obtain the distribution of the conformations, from which the pathway of the conformational change of the protein is deduced.

  14. Alternative approaches to electronic damage by ion-beam irradiation: Exciton models

    Energy Technology Data Exchange (ETDEWEB)

    Agullo-Lopez, F.; Munoz-Martin, A.; Zucchiatti, A. [Centro de Micro-Analisis de Materiales, Universidad Autonoma de Madrid, 28049, Madrid (Spain); Climent-Font, A. [Centro de Micro-Analisis de Materiales, Universidad Autonoma de Madrid, 28049, Madrid (Spain); Departamento de Fisica Aplicada, Universidad Autonoma de Madrid, 28049, Madrid (Spain)

    2016-11-15

    The paper briefly describes the main features of the damage produced by swift heavy ion (SHI) irradiation. After a short revision of the widely used thermal spike concept, it focuses on cumulative mechanisms of track formation which are alternative to those based on lattice melting (thermal spike models). These cumulative mechanisms rely on the production of point defects around the ion trajectory, and their accumulation up to a final lattice collapse or amorphization. As to the formation of point defects, the paper considers those mechanisms relying on direct local conversion of the excitation energy into atomic displacements (exciton models). A particular attention is given to processes based on the non-radiative recombination of excitons that have become self-trapped as a consequence of a strong electron-phonon interaction (STEs). These mechanisms, although operative under purely ionizing radiation in some dielectric materials, have been rarely invoked, so far, to discuss SHI damage. They are discussed in this paper together with relevant examples to materials such as Cu{sub 3}N, alkali halides, SiO{sub 2}, and LiNbO{sub 3}. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. In Silico Modeling of Indigo and Tyrian Purple Single-Electron Nano-Transistors Using Density Functional Theory Approach

    Science.gov (United States)

    Shityakov, Sergey; Roewer, Norbert; Förster, Carola; Broscheit, Jens-Albert

    2017-07-01

    The purpose of this study was to develop and implement an in silico model of indigoid-based single-electron transistor (SET) nanodevices, which consist of indigoid molecules from natural dye weakly coupled to gold electrodes that function in a Coulomb blockade regime. The electronic properties of the indigoid molecules were investigated using the optimized density-functional theory (DFT) with a continuum model. Higher electron transport characteristics were determined for Tyrian purple, consistent with experimentally derived data. Overall, these results can be used to correctly predict and emphasize the electron transport functions of organic SETs, demonstrating their potential for sustainable nanoelectronics comprising the biodegradable and biocompatible materials.

  16. Stationary Electron Atomic Model

    Science.gov (United States)

    Pressler, David E.

    1998-04-01

    I will present a novel theory concerning the position and nature of the electron inside the atom. This new concept is consistant with present experimental evidence and adheres strictly to the valence-shell electron-pair repulsion (VSEPR) model presently used in chemistry for predicting the shapes of molecules and ions. In addition, I will discuss the atomic model concept as being a true harmonic oscillator, periodic motion at resonant frequency which produces radiation at discrete frequencies or line spectra is possible because the electron is under the action of two restoring forces, electrostatic attraction and superconducting respulsion of the electron's magnetic field by the nucleus.

  17. StatSTEM: An efficient approach for accurate and precise model-based quantification of atomic resolution electron microscopy images.

    Science.gov (United States)

    De Backer, A; van den Bos, K H W; Van den Broek, W; Sijbers, J; Van Aert, S

    2016-12-01

    An efficient model-based estimation algorithm is introduced to quantify the atomic column positions and intensities from atomic resolution (scanning) transmission electron microscopy ((S)TEM) images. This algorithm uses the least squares estimator on image segments containing individual columns fully accounting for overlap between neighbouring columns, enabling the analysis of a large field of view. For this algorithm, the accuracy and precision with which measurements for the atomic column positions and scattering cross-sections from annular dark field (ADF) STEM images can be estimated, has been investigated. The highest attainable precision is reached even for low dose images. Furthermore, the advantages of the model-based approach taking into account overlap between neighbouring columns are highlighted. This is done for the estimation of the distance between two neighbouring columns as a function of their distance and for the estimation of the scattering cross-section which is compared to the integrated intensity from a Voronoi cell. To provide end-users this well-established quantification method, a user friendly program, StatSTEM, is developed which is freely available under a GNU public license. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Modeling Incoherent Electron Cloud Effects

    International Nuclear Information System (INIS)

    Vay, Jean-Luc; Benedetto, E.; Fischer, W.; Franchetti, G.; Ohmi, K.; Schulte, D.; Sonnad, K.; Tomas, R.; Vay, J.-L.; Zimmermann, F.; Rumolo, G.; Pivi, M.; Raubenheimer, T.

    2007-01-01

    Incoherent electron effects could seriously limit the beam lifetime in proton or ion storage rings, such as LHC, SPS, or RHIC, or blow up the vertical emittance of positron beams, e.g., at the B factories or in linear-collider damping rings. Different approaches to modeling these effects each have their own merits and drawbacks. We describe several simulation codes which simplify the descriptions of the beam-electron interaction and of the accelerator structure in various different ways, and present results for a toy model of the SPS. In addition, we present evidence that for positron beams the interplay of incoherent electron-cloud effects and synchrotron radiation can lead to a significant increase in vertical equilibrium emittance. The magnitude of a few incoherent e+e- scattering processes is also estimated. Options for future code development are reviewed

  19. A Data-Model Comparison Approach to Understand the Source and Transport Mechanisms of keV-Energy Electrons at Saturn

    Science.gov (United States)

    Santos-Costa, D.; Clark, G. B.; Paranicas, C.; Menietti, J. D.; Tseng, W. L.

    2014-12-01

    We present results from a multi-instrument data analysis and interpretation of Cassini observations that is guided by a theoretical model. Through this analysis, we discuss the source and transport mechanisms of energetic electrons at Saturn and attempt to explain their spatial distributions inside 20 planetary radii (Rs). Using only data sets from equatorial orbits, a recent analysis of Cassini MIMI/LEMMS, CAPS, and MAG data sets by Clark et al. (2014; doi:10.1016/j.pss.2014.07.004) demonstrated how the angular profiles (i.e., 'pancakes', 'isotropic', 'field-aligned', and 'butterfly' PADs) of keV-energy electrons are statistically distributed at Saturn. Through a theoretical transport model, Clark et al. (2014) also demonstrated the role of Saturn's neutral gas torus with adiabatic transport to explain the spatial distribution of electrons. However, their data/model comparison was limited to a case study analysis and the data-model comparison results still do not provide the full picture in understanding the source of keV-energy electrons and their radial evolution. Here we continue to refine our understanding of the spatial distributions of keV-energy electrons at Saturn with the use of a data-model comparison approach. Using the full set of MIMI/LEMMS particle data available for the period mid-2004 to mid-2014, we carefully reexamine the role of neutrals and adiabatic transport for the region ~10 to 15 Rs. Using PAD profiles deduced from data sets at 15 Rs, we build different boundary conditions for our computational model and discuss how angular profiles radially evolve throughout the region ~10-15 Rs and which PADs at our boundary condition can explain the Cassini observations near ~10 Rs. We also present the results from our ongoing investigation of the dominant processes inside ~10 Rs and focus on the impact of chorus emission on the energetic electron distributions.

  20. Ionization Energies, Electron Affinities, and Polarization Energies of Organic Molecular Crystals: Quantitative Estimations from a Polarizable Continuum Model (PCM)–Tuned Range-Separated Density Functional Approach

    KAUST Repository

    Sun, Haitao

    2016-05-16

    We propose a new methodology for the first-principles description of the electronic properties relevant for charge transport in organic molecular crystals. This methodology, which is based on the combination of a non-empirical, optimally tuned range-separated hybrid functional with the polarizable continuum model, is applied to a series of eight representative molecular semiconductor crystals. We show that it provides ionization energies, electron affinities, and transport gaps in very good agreement with experimental values as well as with the results of many-body perturbation theory within the GW approximation at a fraction of the computational costs. Hence, this approach represents an easily applicable and computationally efficient tool to estimate the gas-to-crystal-phase shifts of the frontier-orbital quasiparticle energies in organic electronic materials.

  1. A deterministic model of electron transport for electron probe microanalysis

    Science.gov (United States)

    Bünger, J.; Richter, S.; Torrilhon, M.

    2018-01-01

    Within the last decades significant improvements in the spatial resolution of electron probe microanalysis (EPMA) were obtained by instrumental enhancements. In contrast, the quantification procedures essentially remained unchanged. As the classical procedures assume either homogeneity or a multi-layered structure of the material, they limit the spatial resolution of EPMA. The possibilities of improving the spatial resolution through more sophisticated quantification procedures are therefore almost untouched. We investigate a new analytical model (M 1-model) for the quantification procedure based on fast and accurate modelling of electron-X-ray-matter interactions in complex materials using a deterministic approach to solve the electron transport equations. We outline the derivation of the model from the Boltzmann equation for electron transport using the method of moments with a minimum entropy closure and present first numerical results for three different test cases (homogeneous, thin film and interface). Taking Monte Carlo as a reference, the results for the three test cases show that the M 1-model is able to reproduce the electron dynamics in EPMA applications very well. Compared to classical analytical models like XPP and PAP, the M 1-model is more accurate and far more flexible, which indicates the potential of deterministic models of electron transport to further increase the spatial resolution of EPMA.

  2. The Electronic Dissertation: A less radical approach

    Directory of Open Access Journals (Sweden)

    Andre Costopoulos

    1999-05-01

    Full Text Available Cornelius Holtorf's article in Internet Archaeology, Issue 6 (1999 is a strident call for a radical application of hypermedia techniques to archaeological publishing. Like Holtorf, I recently produced and submitted a Ph.D. dissertation on electronic medium entitled Simulation and Modelling for Anthropological Archaeology (Costopoulos, 1999. My experience of the process, however, was quite different from Holtorf's. While his work concentrates on the hypertextuality of electronic media, mine tends to show the advantages of mass storage and easy access which are inherent to the media. My dissertation is a quite traditionally linear text which is intended to be read sequentially. My effort points, however, to the possibility of including non-textual documents and massive amounts of raw data in an academic publication. I was able to include in my dissertation a working version of my simulation as well as 150 000 pages of simulated data on which the analysis was based. These would clearly have had to be left out of a strictly paper document. In response to Holtorf, I am offering up a short account of the production and submission of my CD dissertation, concentrating on the differences and similarities between the processes we experienced as well as the approaches we used. I plan to present electronic publishing as a natural development of the communication of scientific results rather than as a hypertext revolution.

  3. General derivation of the Green's functions for the atomic approach of the Anderson model: application to a single electron transistor (SET)

    Science.gov (United States)

    Foglio, M. E.; Lobo, T.; Figueira, M. S.

    2012-09-01

    We consider the cumulant expansion of the periodic Anderson model (PAM) in the case of a finite electronic correlation U, employing the hybridization as perturbation, and obtain a formal expression of the exact one-electron Green's function (GF). This expression contains effective cumulants that are as difficult to calculate as the original GF, and the atomic approach consists in substituting the effective cumulants by the ones that correspond to the atomic case, namely by taking a conduction band of zeroth width and local hybridization. In a previous work (T. Lobo, M. S. Figueira, and M. E. Foglio, Nanotechnology 21, 274007 (2010), 10.1088/0957-4484/21/27/274007) we developed the atomic approach by considering only one variational parameter that is used to adjust the correct height of the Kondo peak by imposing the satisfaction of the Friedel sum rule. To obtain the correct width of the Kondo peak in the present work, we consider an additional variational parameter that guarantees this quantity. The two constraints now imposed on the formalism are the satisfaction of the Friedel sum rule and the correct Kondo temperature. In the first part of the work, we present a general derivation of the method for the single impurity Anderson model (SIAM), and we calculate several density of states representative of the Kondo regime for finite correlation U, including the symmetrical case. In the second part, we apply the method to study the electronic transport through a quantum dot (QD) embedded in a quantum wire (QW), which is realized experimentally by a single electron transistor (SET). We calculate the conductance of the SET and obtain a good agreement with available experimental and theoretical results.

  4. Hydrodynamic approach to electronic transport in graphene

    Energy Technology Data Exchange (ETDEWEB)

    Narozhny, Boris N. [Institute for Theoretical Condensed Matter Physics, Karlsruhe Institute of Technology, Karlsruhe (Germany); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Gornyi, Igor V. [Institute for Theoretical Condensed Matter Physics, Karlsruhe Institute of Technology, Karlsruhe (Germany); Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe (Germany); Ioffe Physical Technical Institute, St. Petersburg (Russian Federation); Mirlin, Alexander D. [Institute for Theoretical Condensed Matter Physics, Karlsruhe Institute of Technology, Karlsruhe (Germany); Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe (Germany); Petersburg Nuclear Physics Institute, St. Petersburg (Russian Federation); Schmalian, Joerg [Institute for Theoretical Condensed Matter Physics, Karlsruhe Institute of Technology, Karlsruhe (Germany); Institute for Solid State Physics, Karlsruhe Institute of Technology, Karlsruhe (Germany)

    2017-11-15

    The last few years have seen an explosion of interest in hydrodynamic effects in interacting electron systems in ultra-pure materials. In this paper we briefly review the recent advances, both theoretical and experimental, in the hydrodynamic approach to electronic transport in graphene, focusing on viscous phenomena, Coulomb drag, non-local transport measurements, and possibilities for observing nonlinear effects. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Multidisciplinary Modelling Tools for Power Electronic Circuits

    DEFF Research Database (Denmark)

    Bahman, Amir Sajjad

    package, e.g. power module, DFR approach meets trade-offs in electrical, thermal and mechanical design of the device. Today, virtual prototyping of power electronic circuits using advanced simulation tools is becoming attractive due to cost/time saving in building potential designs. With simulations......This thesis presents multidisciplinary modelling techniques in a Design For Reliability (DFR) approach for power electronic circuits. With increasing penetration of renewable energy systems, the demand for reliable power conversion systems is becoming critical. Since a large part of electricity...... is processed through power electronics, highly efficient, sustainable, reliable and cost-effective power electronic devices are needed. Reliability of a product is defined as the ability to perform within its predefined functions under given conditions in a specific time. Because power electronic devices...

  6. Regenerative electronic biosensors using supramolecular approaches

    NARCIS (Netherlands)

    Duan, X.; Rajan, N.; Routenberg, D.; Huskens, Jurriaan; Reed, M.

    2013-01-01

    A supramolecular interface for Si nanowire FETs has been developed with the aim of creating regenerative electronic biosensors. The key to the approach is Si-NWs functionalized with β-cyclodextrin (β-CD), to which receptor moieties can be attached with an orthogonal supramolecular linker. Here we

  7. Absence of Fungal Spore Internalization by Bronchial Epithelium in Mouse Models Evidenced by a New Bioimaging Approach and Transmission Electronic Microscopy.

    Science.gov (United States)

    Rammaert, Blandine; Jouvion, Grégory; de Chaumont, Fabrice; Garcia-Hermoso, Dea; Szczepaniak, Claire; Renaudat, Charlotte; Olivo-Marin, Jean-Christophe; Chrétien, Fabrice; Dromer, Françoise; Bretagne, Stéphane

    2015-09-01

    Clinical data and experimental studies suggest that bronchial epithelium could serve as a portal of entry for invasive fungal infections. We therefore analyzed the interactions between molds and the bronchial/bronchiolar epithelium at the early steps after inhalation. We developed invasive aspergillosis (Aspergillus fumigatus) and mucormycosis (Lichtheimia corymbifera) murine models that mimic the main clinical risk factors for these infections. Histopathology studies were completed with a specific computer-assisted morphometric method to quantify bronchial and alveolar spores and with transmission electron microscopy. Morphometric analysis revealed a higher number of bronchial/bronchiolar spores for A. fumigatus than L. corymbifera. The bronchial/bronchiolar spores decreased between 1 and 18 hours after inoculation for both fungi, except in corticosteroid-treated mice infected with A. fumigatus, suggesting an effect of cortisone on bronchial spore clearance. No increase in the number of spores of any species was observed over time at the basal pole of the epithelium, suggesting the lack of transepithelial crossing. Transmission electron microscopy did not show spore internalization by bronchial epithelial cells. Instead, spores were phagocytized by mononuclear cells on the apical pole of epithelial cells. Early epithelial internalization of fungal spores in vivo cannot explain the bronchial/bronchiolar epithelium invasion observed in some invasive mold infections. The bioimaging approach provides a useful means to accurately enumerate and localize the fungal spores in the pulmonary tissues. Copyright © 2015 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  8. Electron magnetic resonance data on high-spin Mn(III; S=2) ions in porphyrinic and salen complexes modeled by microscopic spin Hamiltonian approach.

    Science.gov (United States)

    Tadyszak, Krzysztof; Rudowicz, Czesław; Ohta, Hitoshi; Sakurai, Takahiro

    2017-10-01

    The spin Hamiltonian (SH) parameters experimentally determined by EMR (EPR) may be corroborated or otherwise using various theoretical modeling approaches. To this end semiempirical modeling is carried out for high-spin (S=2) manganese (III) 3d 4 ions in complex of tetraphenylporphyrinato manganese (III) chloride (MnTPPCl). This modeling utilizes the microscopic spin Hamiltonians (MSH) approach developed for the 3d 4 and 3d 6 ions with spin S=2 at orthorhombic and tetragonal symmetry sites in crystals, which exhibit an orbital singlet ground state. Calculations of the zero-field splitting (ZFS) parameters and the Zeeman electronic (Ze) factors (g || =g z , g ⊥ =g x =g y ) are carried out for wide ranges of values of the microscopic parameters using the MSH/VBA package. This enables to examine the dependence of the theoretically determined ZFS parameters b k q (in the Stevens notation) and the Zeeman factors g i on the spin-orbit (λ), spin-spin (ρ) coupling constant, and the ligand-field energy levels (Δ i ) within the 5 D multiplet. The results are presented in suitable tables and graphs. The values of λ, ρ, and Δ i best describing Mn(III) ions in MnTPPCl are determined by matching the theoretical second-rank ZFSP b 2 0 (D) parameter and the experimental one. The fourth-rank ZFS parameters (b 4 0 , b 4 4 ) and the ρ (spin-spin)-related contributions, which have been omitted in previous studies, are considered for the first time here and are found important. Semiempirical modeling results are compared with those obtained recently by the density functional theory (DFT) and/or ab initio methods. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Approaching an experimental electron density model of the biologically active trans -epoxysuccinyl amide group-Substituent effects vs. crystal packing

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Ming W.; Stewart, Scott G.; Sobolev, Alexandre N.; Dittrich, Birger; Schirmeister, Tanja; Luger, Peter; Hesse, Malte; Chen, Yu-Sheng; Spackman, Peter R.; Spackman, Mark A.; Grabowsky, Simon (Heinrich-Heine); (Freie); (UC); (Bremen); (JG-UM); (UWA)

    2017-01-24

    The trans-epoxysuccinyl amide group as a biologically active moiety in cysteine protease inhibitors such as loxistatin acid E64c has been used as a benchmark system for theoretical studies of environmental effects on the electron density of small active ingredients in relation to their biological activity. Here, the synthesis and the electronic properties of the smallest possible active site model compound are reported to close the gap between the unknown experimental electron density of trans-epoxysuccinyl amides and the well-known function of related drugs. Intramolecular substituent effects are separated from intermolecular crystal packing effects on the electron density, which allows us to predict the conditions under which an experimental electron density investigation on trans-epoxysuccinyl amides will be possible. In this context, the special importance of the carboxylic acid function in the model compound for both crystal packing and biological activity is revealed through the novel tool of model energy analysis.

  10. Nuclear-electronic orbital nonorthogonal configuration interaction approach.

    Science.gov (United States)

    Skone, Jonathan H; Pak, Michael V; Hammes-Schiffer, Sharon

    2005-10-01

    The nuclear-electronic orbital nonorthogonal configuration interaction (NEO-NOCI) approach is presented. In this framework, the hydrogen nuclei are treated quantum mechanically on the same level as the electrons, and a mixed nuclear-electronic time-independent Schrodinger equation is solved with molecular orbital techniques. For hydrogen transfer systems, the transferring hydrogen is represented by two basis function centers to allow delocalization of the nuclear wave function. In the two-state NEO-NOCI approach, the ground and excited state delocalized nuclear-electronic wave functions are expressed as linear combinations of two nonorthogonal localized nuclear-electronic wave functions obtained at the NEO-Hartree-Fock level. The advantages of the NEO-NOCI approach are the removal of the adiabatic separation between the electrons and the quantum nuclei, the computational efficiency, the potential for systematic improvement by enhancing the basis sets and number of configurations, and the applicability to a broad range of chemical systems. The tunneling splitting is determined by the energy difference between the two delocalized vibronic states. The hydrogen tunneling splittings calculated with the NEO-NOCI approach for the [He-H-He]+ model system with a range of fixed He-He distances are in excellent agreement with NEO-full CI and Fourier grid calculations. These benchmarking calculations indicate that NEO-NOCI is a promising approach for the calculation of delocalized, bilobal hydrogen wave functions and the corresponding hydrogen tunneling splittings.

  11. Electronic resource management systems a workflow approach

    CERN Document Server

    Anderson, Elsa K

    2014-01-01

    To get to the bottom of a successful approach to Electronic Resource Management (ERM), Anderson interviewed staff at 11 institutions about their ERM implementations. Among her conclusions, presented in this issue of Library Technology Reports, is that grasping the intricacies of your workflow-analyzing each step to reveal the gaps and problems-at the beginning is crucial to selecting and implementing an ERM. Whether the system will be used to fill a gap, aggregate critical data, or replace a tedious manual process, the best solution for your library depends on factors such as your current soft

  12. The Connecting South West Ontario (cSWO) Benefits Model: An Approach for the Collaborative Capture of Value of Electronic Health Records and Enabling Technology.

    Science.gov (United States)

    Alexander, Ted; Huebner, Lori-Anne; Alarakhia, Mohamed; Hollohan, Kirk

    2017-01-01

    This paper explains the benefits model developed and deployed by the connecting South West Ontario (cSWO) program. The cSWO approach is founded on the principles of enabling clinical and organizational value and the recognition that enabling requires a collaborative approach that can include several perspectives. We describe our approach which is aimed at creating a four-part harmony between change management and adoption, best practice research and quality indicators, data analytics and clinical value production.

  13. Models of fast-electron penetration

    International Nuclear Information System (INIS)

    Perry, D.J.; Raisis, S.K.

    1994-01-01

    We introduce multiple scattering models of charged-particle penetration which are based on the previous analyses of Yang and Perry. Our development removes the main limitations of the Fermi-Eyges approach while retaining its considerable potential as a theory which is useful for applied work. We illustrate key predictions with sample calculations that are of particular interest in therapeutic applications, 5-20 MeV electrons incident on water. 8 refs., 5 figs

  14. Interacting electrons theory and computational approaches

    CERN Document Server

    Martin, Richard M; Ceperley, David M

    2016-01-01

    Recent progress in the theory and computation of electronic structure is bringing an unprecedented level of capability for research. Many-body methods are becoming essential tools vital for quantitative calculations and understanding materials phenomena in physics, chemistry, materials science and other fields. This book provides a unified exposition of the most-used tools: many-body perturbation theory, dynamical mean field theory and quantum Monte Carlo simulations. Each topic is introduced with a less technical overview for a broad readership, followed by in-depth descriptions and mathematical formulation. Practical guidelines, illustrations and exercises are chosen to enable readers to appreciate the complementary approaches, their relationships, and the advantages and disadvantages of each method. This book is designed for graduate students and researchers who want to use and understand these advanced computational tools, get a broad overview, and acquire a basis for participating in new developments.

  15. HEDR modeling approach

    International Nuclear Information System (INIS)

    Shipler, D.B.; Napier, B.A.

    1992-07-01

    This report details the conceptual approaches to be used in calculating radiation doses to individuals throughout the various periods of operations at the Hanford Site. The report considers the major environmental transport pathways--atmospheric, surface water, and ground water--and projects and appropriate modeling technique for each. The modeling sequence chosen for each pathway depends on the available data on doses, the degree of confidence justified by such existing data, and the level of sophistication deemed appropriate for the particular pathway and time period being considered

  16. Modeling prosody: Different approaches

    Science.gov (United States)

    Carmichael, Lesley M.

    2002-11-01

    Prosody pervades all aspects of a speech signal, both in terms of raw acoustic outcomes and linguistically meaningful units, from the phoneme to the discourse unit. It is carried in the suprasegmental features of fundamental frequency, loudness, and duration. Several models have been developed to account for the way prosody organizes speech, and they vary widely in terms of their theoretical assumptions, organizational primitives, actual procedures of application to speech, and intended use (e.g., to generate speech from text vs. to model the prosodic phonology of a language). In many cases, these models overtly contradict one another with regard to their fundamental premises or their identification of the perceptible objects of linguistic prosody. These competing models are directly compared. Each model is applied to the same speech samples. This parallel analysis allows for a critical inspection of each model and its efficacy in assessing the suprasegmental behavior of the speech. The analyses illustrate how different approaches are better equipped to account for different aspects of prosody. Viewing the models and their successes from an objective perspective allows for creative possibilities in terms of combining strengths from models which might otherwise be considered fundamentally incompatible.

  17. Mathematical model I. Electron and quantum mechanics

    Directory of Open Access Journals (Sweden)

    Nitin Ramchandra Gadre

    2011-03-01

    Full Text Available The basic particle electron obeys various theories like electrodynamics, quantum mechanics and special relativity. Particle under different experimental conditions behaves differently, allowing us to observe different characteristics which become basis for these theories. In this paper, we have made an attempt to suggest a classical picture by studying the requirements of these three modern theories. The basic presumption is: There must be certain structural characteristics in a particle like electron which make it obey postulates of modern theories. As it is ‘difficult’ to find structure of electron experimentally, we make a mathematical attempt. For a classical approach, we require well defined systems and we have studied a system with two charged particles, proton and electron in a hydrogen atom. An attempt has been made to give a model to describe electron as seen by the proton. We then discuss how the model can satisfy the requirements of the three modern theories in a classical manner. The paper discusses basic aspects of relativity and electrodynamics. However the focus of the paper is on quantum mechanics.

  18. Mathematical model I. Electron and quantum mechanics

    Science.gov (United States)

    Gadre, Nitin Ramchandra

    2011-03-01

    The basic particle electron obeys various theories like electrodynamics, quantum mechanics and special relativity. Particle under different experimental conditions behaves differently, allowing us to observe different characteristics which become basis for these theories. In this paper, we have made an attempt to suggest a classical picture by studying the requirements of these three modern theories. The basic presumption is: There must be certain structural characteristics in a particle like electron which make it obey postulates of modern theories. As it is `difficult' to find structure of electron experimentally, we make a mathematical attempt. For a classical approach, we require well defined systems and we have studied a system with two charged particles, proton and electron in a hydrogen atom. An attempt has been made to give a model to describe electron as seen by the proton. We then discuss how the model can satisfy the requirements of the three modern theories in a classical manner. The paper discusses basic aspects of relativity and electrodynamics. However the focus of the paper is on quantum mechanics.

  19. Path-integral approach to resonant electron-molecule scattering

    International Nuclear Information System (INIS)

    Winterstetter, M.; Domcke, W.

    1993-01-01

    A path-integral formulation of resonant electron-molecule scattering is developed within the framework of the projection-operator formalism of scattering theory. The formation and decay of resonances is treated in real time as a quantum-mechanical electronic-tunneling process, modified by the coupling of the electronic motion with the nuclear degrees of freedom. It is shown that the electronic continuum can be summed over in the path-integral formulation, resulting formally in the path integral for an effective two-state system with coupling to vibrations. The harmonic-oscillator approximation is adopted for the vibrational motion in the present work. Approximation methods are introduced which render the numerical evaluation of the sum over paths feasible for up to ∼10 3 elementary time slices. The theory is numerically realized for simple but nontrivial models representing the 2 Π g d-wave shape resonance in e - +N 2 collisions and the 2 Σ u + p-wave shape resonance in e - +H 2 collisions, respectively. The accuracy of the path-integral results is assessed by comparison with exact numerical reference data for these models. The essential virtue of the path-integral approach is the fact that the computational effort scales at most linearly with the number of vibrational degrees of freedom. The path-integral method is thus well suited to treat electron collisions with polyatomic molecules and molecular aggregates

  20. Convergent Close-Coupling Approach to Electron-Atom Collisions

    Science.gov (United States)

    Bray, Igor; Stelbovics, Andris

    2007-01-01

    It was with great pleasure and honour to accept the invitation to make a presentation at the symposium celebrating the life-long work of Aaron Temkin and Richard Drachman. The work of Aaron Temkin was particularly influential on our own during the development of the CCC method for electron-atom collisions. There are a number of key problems that need to be dealt with when developing a general computational approach to such collisions. Traditionally, the electron energy range was subdivided into the low, intermediate, and high energies. At the low energies only a finite number of channels are open and variational or close-coupling techniques could be used to obtain accurate results. At high energies an infinite number of discrete channels and the target continuum are open, but perturbative techniques are able to yield accurate results. However, at the intermediate energies perturbative techniques fail and computational approaches need to be found for treating the infinite number of open channels. In addition, there are also problems associated with the identical nature of electrons and the difficulty of implementing the boundary conditions for ionization processes. The beauty of the Temkin-Poet model of electron-hydrogen scattering is that it simplifies the full computational problem by neglecting any non-zero orbital angular momenta in the partial-wave expansion, without loosing the complexity associated with the above-mentioned problems. The unique nature of the problem allowed for accurate solution leading to benchmark results which could then be used to test the much more general approaches to electron-atom collision problems. The immense value of the Temkin-Poet model is readily summarised by the fact that the initial papers of Temkin and Poet have been collectively cited around 250 times to date and are still being cited in present times. Many of the citations came from our own work during the course of the development of the CCC method, which we now describe.

  1. Local control approach to ultrafast electron transfer

    Energy Technology Data Exchange (ETDEWEB)

    Vindel-Zandbergen, Patricia [Departamento de Química Física, Universidad Complutense, 28040 Madrid (Spain); Meier, Christoph [Laboratoire Colisions, Agrégats et Reactivité, UMR 5589, IRSAMC, Université Paul Sabatier, 31062 Toulouse (France); Sola, Ignacio R., E-mail: isola@quim.ucm.es [Departamento de Química Física, Universidad Complutense, 28040 Madrid (Spain)

    2016-10-20

    We study ultrafast electron transfer between separated nuclei using local control theory. By imposing electron ionization and electron transport through the continuum, different local control formulations are used to increase the yield of retrapping the electron at the desired nuclei. The control mechanism is based on impulsive de-excitation. Both symmetric and asymmetric nuclear arrangements are analyzed, as well as the role of the nuclear motion.

  2. Effective approaches for managing electronic records and archives

    CERN Document Server

    Dearstyne, Bruce W

    2006-01-01

    This is a book of fresh insights, perspectives, strategies, and approaches for managing electronic records and archives. The authors draw on first-hand experience to present practical solutions, including recommendations for building and sustaining strong electronic records programs.

  3. CONCEPTUAL APPROACHES TO THE CREATION OF UNIVERSITY ELECTRONIC LIBRARIES

    Directory of Open Access Journals (Sweden)

    P. M. Lapo

    2013-01-01

    Full Text Available The peculiarities of informatization in education, conceptual approaches to the creation of electronic libraries, as well as the content and the rating of the electronic library of Belarusian State University are considered.

  4. Bonding and Molecular Geometry without Orbitals- The Electron Domain Model

    Science.gov (United States)

    Gillespie, Ronald J.; Spencer, James N.; Moog, Richard S.

    1996-07-01

    An alternative to the conventional valence bond approach to bonding and geometry-the electron domain model-is presented. This approach avoids some of the problems with the standard approach and presents fewer difficulties for the student, while still providing a physical basis for the VSEPR model and a link to the valence bond model. The electron domain model also emphasizes the importance of the Pauli principle in understanding the chemical bond and molecular geometry. A letter from Derek W. Smith in our April 2000 issue addresses the above.

  5. A stakeholder approach to electronic commerce diffusion

    OpenAIRE

    Papazafeiropoulou, Anastasia

    2002-01-01

    This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University. The evolution of electronic commerce as a global technological innovation raised a number of issues related to its adoption. Specifically, although electronic commerce use by companies has been associated with significant opportunities for growth, it has not been adopted in full. Small and Medium Size Enterprises (SMEs) in particular seem to hesitate to invest in electronic commerce technolog...

  6. Modeling Electronic Properties of Complex Oxides

    Science.gov (United States)

    Krishnaswamy, Karthik

    Complex oxides are a class of materials that have recently emerged as potential candidates for electronic applications owing to their interesting electronic properties. The goal of this dissertation is to develop a fundamental understanding of these electronic properties using a combination of first-principles approaches based on density functional theory (DFT), and Schrodinger-Poisson (SP) simulation (Abstract shortened by ProQuest.

  7. Electronics Lab Instructors' Approaches to Troubleshooting Instruction

    Science.gov (United States)

    Dounas-Frazer, Dimitri R.; Lewandowski, H. J.

    2017-01-01

    In this exploratory qualitative study, we describe instructors' self-reported practices for teaching and assessing students' ability to troubleshoot in electronics lab courses. We collected audio data from interviews with 20 electronics instructors from 18 institutions that varied by size, selectivity, and other factors. In addition to describing…

  8. Material Modelling - Composite Approach

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    1997-01-01

    This report is part of a research project on "Control of Early Age Cracking" - which, in turn, is part of the major research programme, "High Performance Concrete - The Contractor's Technology (HETEK)", coordinated by the Danish Road Directorate, Copenhagen, Denmark, 1997.A composite-rheological ......This report is part of a research project on "Control of Early Age Cracking" - which, in turn, is part of the major research programme, "High Performance Concrete - The Contractor's Technology (HETEK)", coordinated by the Danish Road Directorate, Copenhagen, Denmark, 1997.A composite......-rheological model of concrete is presented by which consistent predictions of creep, relaxation, and internal stresses can be made from known concrete composition, age at loading, and climatic conditions. No other existing "creep prediction method" offers these possibilities in one approach.The model...... in this report is that cement paste and concrete behave practically as linear-viscoelastic materials from an age of approximately 10 hours. This is a significant age extension relative to earlier studies in the literature where linear-viscoelastic behavior is only demonstrated from ages of a few days. Thus...

  9. Teaching Behavioral Modeling and Simulation Techniques for Power Electronics Courses

    Science.gov (United States)

    Abramovitz, A.

    2011-01-01

    This paper suggests a pedagogical approach to teaching the subject of behavioral modeling of switch-mode power electronics systems through simulation by general-purpose electronic circuit simulators. The methodology is oriented toward electrical engineering (EE) students at the undergraduate level, enrolled in courses such as "Power…

  10. Modeling of power electronic systems with EMTP

    Science.gov (United States)

    Tam, Kwa-Sur; Dravid, Narayan V.

    1989-01-01

    In view of the potential impact of power electronics on power systems, there is need for a computer modeling/analysis tool to perform simulation studies on power systems with power electronic components as well as to educate engineering students about such systems. The modeling of the major power electronic components of the NASA Space Station Freedom Electric Power System is described along with ElectroMagnetic Transients Program (EMTP) and it is demonstrated that EMTP can serve as a very useful tool for teaching, design, analysis, and research in the area of power systems with power electronic components. EMTP modeling of power electronic circuits is described and simulation results are presented.

  11. A kinetic model for runaway electrons in the ionosphere

    Directory of Open Access Journals (Sweden)

    G. Garcia

    2006-09-01

    Full Text Available Electrodynamic models and measurements with satellites and incoherent scatter radars predict large field aligned current densities on one side of the auroral arcs. Different authors and different kinds of studies (experimental or modeling agree that the current density can reach up to hundreds of µA/m2. This large current density could be the cause of many phenomena such as tall red rays or triggering of unstable ion acoustic waves. In the present paper, we consider the issue of electrons moving through an ionospheric gas of positive ions and neutrals under the influence of a static electric field. We develop a kinetic model of collisions including electrons/electrons, electrons/ions and electrons/neutrals collisions. We use a Fokker-Planck approach to describe binary collisions between charged particles with a long-range interaction. We present the essential elements of this collision operator: the Langevin equation for electrons/ions and electrons/electrons collisions and the Monte-Carlo and null collision methods for electrons/neutrals collisions. A computational example is given illustrating the approach to equilibrium and the impact of the different terms (electrons/electrons and electrons/ions collisions on the one hand and electrons/neutrals collisions on the other hand. Then, a parallel electric field is applied in a new sample run. In this run, the electrons move in the z direction parallel to the electric field. The first results show that all the electron distribution functions are non-Maxwellian. Furthermore, runaway electrons can carry a significant part of the total current density, up to 20% of the total current density.

  12. A kinetic model for runaway electrons in the ionosphere

    Directory of Open Access Journals (Sweden)

    G. Garcia

    2006-09-01

    Full Text Available Electrodynamic models and measurements with satellites and incoherent scatter radars predict large field aligned current densities on one side of the auroral arcs. Different authors and different kinds of studies (experimental or modeling agree that the current density can reach up to hundreds of µA/m2. This large current density could be the cause of many phenomena such as tall red rays or triggering of unstable ion acoustic waves. In the present paper, we consider the issue of electrons moving through an ionospheric gas of positive ions and neutrals under the influence of a static electric field. We develop a kinetic model of collisions including electrons/electrons, electrons/ions and electrons/neutrals collisions. We use a Fokker-Planck approach to describe binary collisions between charged particles with a long-range interaction. We present the essential elements of this collision operator: the Langevin equation for electrons/ions and electrons/electrons collisions and the Monte-Carlo and null collision methods for electrons/neutrals collisions. A computational example is given illustrating the approach to equilibrium and the impact of the different terms (electrons/electrons and electrons/ions collisions on the one hand and electrons/neutrals collisions on the other hand. Then, a parallel electric field is applied in a new sample run. In this run, the electrons move in the z direction parallel to the electric field. The first results show that all the electron distribution functions are non-Maxwellian. Furthermore, runaway electrons can carry a significant part of the total current density, up to 20% of the total current density.

  13. Analytical local electron-electron interaction model potentials for atoms

    International Nuclear Information System (INIS)

    Neugebauer, Johannes; Reiher, Markus; Hinze, Juergen

    2002-01-01

    Analytical local potentials for modeling the electron-electron interaction in an atom reduce significantly the computational effort in electronic structure calculations. The development of such potentials has a long history, but some promising ideas have not yet been taken into account for further improvements. We determine a local electron-electron interaction potential akin to those suggested by Green et al. [Phys. Rev. 184, 1 (1969)], which are widely used in atom-ion scattering calculations, electron-capture processes, and electronic structure calculations. Generalized Yukawa-type model potentials are introduced. This leads, however, to shell-dependent local potentials, because the origin behavior of such potentials is different for different shells as has been explicated analytically [J. Neugebauer, M. Reiher, and J. Hinze, Phys. Rev. A 65, 032518 (2002)]. It is found that the parameters that characterize these local potentials can be interpolated and extrapolated reliably for different nuclear charges and different numbers of electrons. The analytical behavior of the corresponding localized Hartree-Fock potentials at the origin and at long distances is utilized in order to reduce the number of fit parameters. It turns out that the shell-dependent form of Green's potential, which we also derive, yields results of comparable accuracy using only one shell-dependent parameter

  14. Computational Approach to Electron Charge Transfer Reactions

    DEFF Research Database (Denmark)

    Jónsson, Elvar Örn

    The step from ab initio atomic and molecular properties to thermodynamic - or macroscopic - properties requires the combination of several theoretical tools. This dissertation presents constant temperature molecular dynamics with bond length constraints, a hybrid quantum mechanics-molecular mecha...... structure modes. This is for a large iridium-iridium dimer complex which shows a dramatic structural (and vibrational) change upon electronic excitation....

  15. Boltzmann-Electron Model in Aleph.

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Thomas Patrick; Hooper, Russell

    2014-11-01

    We apply the Boltzmann-electron model in the electrostatic, particle-in-cell, finite- element code Aleph to a plasma sheath. By assuming a Boltzmann energy distribution for the electrons, the model eliminates the need to resolve the electron plasma fre- quency, and avoids the numerical "grid instability" that can cause unphysical heating of electrons. This allows much larger timesteps to be used than with kinetic electrons. Ions are treated with the standard PIC algorithm. The Boltzmann-electron model re- quires solution of a nonlinear Poisson equation, for which we use an iterative Newton solver (NOX) from the Trilinos Project. Results for the spatial variation of density and voltage in the plasma sheath agree well with an analytic model

  16. NASA and COTS Electronics: Past Approach and Successes - Future Considerations

    Science.gov (United States)

    LaBel, Kenneth A.

    2018-01-01

    NASA has a long history of using commercial grade electronics in space. In this talk, a brief history of NASAâ's trends and approaches to commercial grade electronics focusing on processing and memory systems will be presented. This will include providing summary information on the space hazards to electronics as well as NASA mission trade space. We will also discuss developing recommendations for risk management approaches to Electrical, Electronic and Electromechanical (EEE) parts and reliability in space. The final portion of the talk will discuss emerging aerospace trends and the future for Commercial Off The Shelf (COTS) usage.

  17. Reduced explicitly correlated Hartree-Fock approach within the nuclear-electronic orbital framework: theoretical formulation.

    Science.gov (United States)

    Sirjoosingh, Andrew; Pak, Michael V; Swalina, Chet; Hammes-Schiffer, Sharon

    2013-07-21

    The nuclear-electronic orbital (NEO) method treats electrons and select nuclei quantum mechanically on the same level to extend beyond the Born-Oppenheimer approximation. Electron-nucleus dynamical correlation has been found to be highly significant due to the attractive Coulomb interaction. The explicitly correlated Hartree-Fock (NEO-XCHF) approach includes explicit electron-nucleus correlation with Gaussian-type geminal functions during the variational optimization of the nuclear-electronic wavefunction. Although accurate for small model systems, the NEO-XCHF method is computationally impractical for larger chemical systems. In this paper, we develop the reduced explicitly correlated Hartree-Fock approach, denoted NEO-RXCHF, where only select electronic orbitals are explicitly correlated to the nuclear orbitals. By explicitly correlating only the relevant electronic orbitals to the nuclear orbitals, the NEO-RXCHF approach avoids problems that can arise when all electronic orbitals are explicitly correlated to the nuclear orbitals in the same manner. We examine three different NEO-RXCHF methods that differ in the treatment of the exchange between the geminal-coupled electronic orbitals and the other electronic orbitals: NEO-RXCHF-fe is fully antisymmetric with respect to exchange of all electronic coordinates and includes all electronic exchange terms; NEO-RXCHF-ne neglects the exchange between the geminal-coupled electronic orbitals and the other electronic orbitals; and NEO-RXCHF-ae includes approximate exchange terms between the geminal-coupled electronic orbitals and the other electronic orbitals. The latter two NEO-RXCHF methods offer substantial computational savings over the NEO-XCHF approach. The NEO-RXCHF approach is applicable to a wide range of chemical systems that exhibit non-Born-Oppenheimer effects between electrons and nuclei, as well as positron-containing molecular systems.

  18. FTL Quantum Models of the Photon and the Electron

    International Nuclear Information System (INIS)

    Gauthier, Richard F.

    2007-01-01

    A photon is modeled by an uncharged superluminal quantum moving at 1.414c along an open 45-degree helical trajectory with radius R = λ/2π (where λ is the helical pitch or wavelength). A mostly superluminal spatial model of an electron is composed of a charged pointlike quantum circulating at an extremely high frequency ( 2.5 x 1020 hz) in a closed, double-looped hehcal trajectory whose helical pitch is one Compton wavelength h/mc. The quantum has energy and momentum but not rest mass, so its speed is not limited by c. sThe quantum's speed is superluminal 57% of the time and subluminal 43% of the time, passing through c twice in each trajectory cycle. The quantum's maximum speed in the electron's rest frame is 2.515c and its minimum speed is .707c. The electron model's helical trajectory parameters are selected to produce the electron's spin (ℎ/2π)/2 and approximate (without small QED corrections) magnetic moment e(ℎ/2π)/2m (the Bohr magneton μB) as well as its Dirac equation-related 'jittery motion' angular frequency 2mc2/(ℎ/2π), amplitude (ℎ/2π)/2mc and internal speed c. The two possible helicities of the electron model correspond to the electron and the positron. With these models, an electron is like a closed circulating photon. The electron's inertia is proposed to be related to the electron model's circulating internal Compton momentum mc. The internal superluminalily of the photon model, the internal superluminahty/subluminality of the electron model, and the proposed approach to the electron's inertia as ''momentum at rest'' within the electron, could be relevant to possible mechanisms of superluminal communication and transportation

  19. Electronic waste management approaches: an overview.

    Science.gov (United States)

    Kiddee, Peeranart; Naidu, Ravi; Wong, Ming H

    2013-05-01

    Electronic waste (e-waste) is one of the fastest-growing pollution problems worldwide given the presence if a variety of toxic substances which can contaminate the environment and threaten human health, if disposal protocols are not meticulously managed. This paper presents an overview of toxic substances present in e-waste, their potential environmental and human health impacts together with management strategies currently being used in certain countries. Several tools including life cycle assessment (LCA), material flow analysis (MFA), multi criteria analysis (MCA) and extended producer responsibility (EPR) have been developed to manage e-wastes especially in developed countries. The key to success in terms of e-waste management is to develop eco-design devices, properly collect e-waste, recover and recycle material by safe methods, dispose of e-waste by suitable techniques, forbid the transfer of used electronic devices to developing countries, and raise awareness of the impact of e-waste. No single tool is adequate but together they can complement each other to solve this issue. A national scheme such as EPR is a good policy in solving the growing e-waste problems. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  20. Modeling ion sensing in molecular electronics

    Science.gov (United States)

    Chen, Caroline J.; Smeu, Manuel; Ratner, Mark A.

    2014-02-01

    We examine the ability of molecules to sense ions by measuring the change in molecular conductance in the presence of such charged species. The detection of protons (H+), alkali metal cations (M+), calcium ions (Ca2+), and hydronium ions (H3O+) is considered. Density functional theory (DFT) is used within the Keldysh non-equilibrium Green's function framework (NEGF) to model electron transport properties of quinolinedithiol (QDT, C9H7NS2), bridging Al electrodes. The geometry of the transport region is relaxed with DFT. The transport properties of the device are modeled with NEGF-DFT to determine if this device can distinguish among the M+ + QDT species containing monovalent cations, where M+ = H+, Li+, Na+, or K+. Because of the asymmetry of QDT in between the two electrodes, both positive and negative biases are considered. The electron transmission function and conductance properties are simulated for electrode biases in the range from -0.5 V to 0.5 V at increments of 0.1 V. Scattering state analysis is used to determine the molecular orbitals that are the main contributors to the peaks in the transmission function near the Fermi level of the electrodes, and current-voltage relationships are obtained. The results show that QDT can be used as a proton detector by measuring transport through it and can conceivably act as a pH sensor in solutions. In addition, QDT may be able to distinguish among different monovalent species. This work suggests an approach to design modern molecular electronic conductance sensors with high sensitivity and specificity using well-established quantum chemistry.

  1. Global approaches to regulating electronic cigarettes

    OpenAIRE

    Kennedy, Ryan David; Awopegba, Ayodeji; De Le?n, Elaine; Cohen, Joanna E

    2016-01-01

    Objectives Classify and describe the policy approaches used by countries to regulate e-cigarettes. Methods National policies regulating e-cigarettes were identified by (1) conducting web searches on Ministry of Health websites, and (2) broad web searches. The mechanisms used to regulate e-cigarettes were classified as new/amended laws, or existing laws. The policy domains identified include restrictions or prohibitions on product: sale, manufacturing, importation, distribution, use, product d...

  2. Electronic waste management approaches: An overview

    International Nuclear Information System (INIS)

    Kiddee, Peeranart; Naidu, Ravi; Wong, Ming H.

    2013-01-01

    Highlights: ► Human toxicity of hazardous substances in e-waste. ► Environmental impacts of e-waste from disposal processes. ► Life Cycle Assessment (LCA), Material Flow Analysis (MFA), Multi Criteria Analysis (MCA) and Extended Producer Responsibility (EPR) to and solve e-waste problems. ► Key issues relating to tools managing e-waste for sustainable e-waste management. - Abstract: Electronic waste (e-waste) is one of the fastest-growing pollution problems worldwide given the presence if a variety of toxic substances which can contaminate the environment and threaten human health, if disposal protocols are not meticulously managed. This paper presents an overview of toxic substances present in e-waste, their potential environmental and human health impacts together with management strategies currently being used in certain countries. Several tools including Life Cycle Assessment (LCA), Material Flow Analysis (MFA), Multi Criteria Analysis (MCA) and Extended Producer Responsibility (EPR) have been developed to manage e-wastes especially in developed countries. The key to success in terms of e-waste management is to develop eco-design devices, properly collect e-waste, recover and recycle material by safe methods, dispose of e-waste by suitable techniques, forbid the transfer of used electronic devices to developing countries, and raise awareness of the impact of e-waste. No single tool is adequate but together they can complement each other to solve this issue. A national scheme such as EPR is a good policy in solving the growing e-waste problems

  3. Toward Modeling the Social Edition: An Approach to Understanding the Electronic Scholarly Edition in the Context of New and Emerging Social Media

    NARCIS (Netherlands)

    Siemens, R.; Timney, M.; Leitch, C.; Koolen, C.; Garnett, A.

    2012-01-01

    This article explores building blocks in extant and emerging social media toward the possibilities they offer to the scholarly edition in electronic form, positing that we are witnessing the nascent stages of a new ‘social’ edition existing at the intersection of social media and digital editing.

  4. A Dictionary Approach to Electron Backscatter Diffraction Indexing.

    Science.gov (United States)

    Chen, Yu H; Park, Se Un; Wei, Dennis; Newstadt, Greg; Jackson, Michael A; Simmons, Jeff P; De Graef, Marc; Hero, Alfred O

    2015-06-01

    We propose a framework for indexing of grain and subgrain structures in electron backscatter diffraction patterns of polycrystalline materials. We discretize the domain of a dynamical forward model onto a dense grid of orientations, producing a dictionary of patterns. For each measured pattern, we identify the most similar patterns in the dictionary, and identify boundaries, detect anomalies, and index crystal orientations. The statistical distribution of these closest matches is used in an unsupervised binary decision tree (DT) classifier to identify grain boundaries and anomalous regions. The DT classifies a pattern as an anomaly if it has an abnormally low similarity to any pattern in the dictionary. It classifies a pixel as being near a grain boundary if the highly ranked patterns in the dictionary differ significantly over the pixel's neighborhood. Indexing is accomplished by computing the mean orientation of the closest matches to each pattern. The mean orientation is estimated using a maximum likelihood approach that models the orientation distribution as a mixture of Von Mises-Fisher distributions over the quaternionic three sphere. The proposed dictionary matching approach permits segmentation, anomaly detection, and indexing to be performed in a unified manner with the additional benefit of uncertainty quantification.

  5. A Unified Model of Secondary Electron Cascades in Diamond

    Energy Technology Data Exchange (ETDEWEB)

    Ziaja, B; London, R A; Hajdu, J

    2004-10-13

    In this paper we present a detailed and unified theoretical treatment of secondary electron cascades that follow the absorption of an X-ray photon. A Monte Carlo model has been constructed that treats in detail the evolution of electron cascades induced by photoelectrons and by Auger electrons following inner shell ionizations. Detailed calculations are presented for cascades initiated by electron energies between 0.1-10 keV. The present paper expands our earlier work by extending the primary energy range, by improving the treatment of secondary electrons, especially at low electron energies, by including ionization by holes, and by taking into account their coupling to the crystal lattice. The calculations describe the three-dimensional evolution of the electron cloud, and monitor the equivalent instantaneous temperature of the free-electron gas as the system cools. The dissipation of the impact energy proceeds predominantly through the production of secondary electrons whose energies are comparable to the binding energies of the valence (40-50 eV) and of the core electrons (300 eV). The electron cloud generated by a 10 keV electron is strongly anisotropic in the early phases of the cascade (t {le} 1 fs). At later times, the sample is dominated by low energy electrons, and these are scattered more isotropically by atoms in the sample. Our results for the total late time number of secondary electrons agree with available experimental data, and show that the emission of secondary electrons approaches saturation within about 100 fs, following the primary impact.

  6. Fuse Modeling for Reliability Study of Power Electronic Circuits

    DEFF Research Database (Denmark)

    Bahman, Amir Sajjad; Iannuzzo, Francesco; Blaabjerg, Frede

    2017-01-01

    This paper describes a comprehensive modeling approach on reliability of fuses used in power electronic circuits. When fuses are subjected to current pulses, cyclic temperature stress is introduced to the fuse element and will wear out the component. Furthermore, the fuse may be used in a large v...

  7. Pspice and Matlab for electronics an integrated approach

    CERN Document Server

    Attia, John Okyere

    2010-01-01

    Used collectively, PSPICE and MATLAB[registered] are unsurpassed for circuit modeling and data analysis. This title illustrates how to use the strong features of PSpice and the powerful functions of MATLAB for electronic circuit analysis.

  8. Visualized attribute analysis approach for characterization and quantification of rice taste flavor using electronic tongue.

    Science.gov (United States)

    Lu, Lin; Hu, Xianqiao; Tian, Shiyi; Deng, Shaoping; Zhu, Zhiwei

    2016-05-05

    This paper deals with a novel visualized attributive analysis approach for characterization and quantification of rice taste flavor attributes (softness, stickiness, sweetness and aroma) employing a multifrequency large-amplitude pulse voltammetric electronic tongue. Data preprocessing methods including Principal Component Analysis (PCA) and Fast Fourier Transform (FFT) were provided. An attribute characterization graph was represented for visualization of the interactive response in which each attribute responded by specific electrodes and frequencies. The model was trained using signal data from electronic tongue and attribute scores from artificial evaluation. The correlation coefficients for all attributes were over 0.9, resulting in good predictive ability of attributive analysis model preprocessed by FFT. This approach extracted more effective information about linear relationship between electronic tongue and taste flavor attribute. Results indicated that this approach can accurately quantify taste flavor attributes, and can be an efficient tool for data processing in a voltammetric electronic tongue system. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Understanding electron magnetic circular dichroism in a transition potential approach

    Science.gov (United States)

    Barthel, J.; Mayer, J.; Rusz, J.; Ho, P.-L.; Zhong, X. Y.; Lentzen, M.; Dunin-Borkowski, R. E.; Urban, K. W.; Brown, H. G.; Findlay, S. D.; Allen, L. J.

    2018-04-01

    This paper introduces an approach based on transition potentials for inelastic scattering to understand the underlying physics of electron magnetic circular dichroism (EMCD). The transition potentials are sufficiently localized to permit atomic-scale EMCD. Two-beam and three-beam systematic row cases are discussed in detail in terms of transition potentials for conventional transmission electron microscopy, and the basic symmetries which arise in the three-beam case are confirmed experimentally. Atomic-scale EMCD in scanning transmission electron microscopy (STEM), using both a standard STEM probe and vortex beams, is discussed.

  10. Theoretical model of fast electron emission from surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Reinhold, C.; Burgdoerfer, J. [Univ. of Tennessee, Knoxville, TN (United States)]|[Oak Ridge National Laboratory, TN (United States)

    1993-05-01

    Electron emission in glancing-angle ion-surface collisions has become a focus of ion-surface interactions. Electron spectra can provide detailed information on the above surface neutralization dynamics of multiply charged ions, the electronic structure of the surface (surface density of states), and the long-ranged image interactions near the surface. Recent experiments have found that the convoy peak, well known from ion-atom and ion-solid collisions, is dramatically altered. The peak is broadened and shifted in energy which has been attributed to dynamical image interactions. We present a microscopic model for the emission of fast electrons in glancing-angle surface collisions. A classical trajectory Monte Carlo approach is utilized to calculate the evolution of electrons in the presence of their self image, the projectile Coulomb field and the image potential induced by the projectile. The excitation of collective surface modes is also incorporated.

  11. Electron-Ionic Model of Ball Lightening

    OpenAIRE

    Fedosin, Sergey G.; Kim, Anatolii S.

    2001-01-01

    The model of ball lightning is presented where outside electron envelope is kept by inside volume of positive charges. The moving of electron in outside envelope is a reason of strong magnetic field, which controls the state of hot ionized air inside of ball lightning. The conditions of origins of ball lightning are investigated and the values of parameters for ball lightning of maximum power are calculated.

  12. Toward Environmentally Robust Organic Electronics: Approaches and Applications.

    Science.gov (United States)

    Lee, Eun Kwang; Lee, Moo Yeol; Park, Cheol Hee; Lee, Hae Rang; Oh, Joon Hak

    2017-11-01

    Recent interest in flexible electronics has led to a paradigm shift in consumer electronics, and the emergent development of stretchable and wearable electronics is opening a new spectrum of ubiquitous applications for electronics. Organic electronic materials, such as π-conjugated small molecules and polymers, are highly suitable for use in low-cost wearable electronic devices, and their charge-carrier mobilities have now exceeded that of amorphous silicon. However, their commercialization is minimal, mainly because of weaknesses in terms of operational stability, long-term stability under ambient conditions, and chemical stability related to fabrication processes. Recently, however, many attempts have been made to overcome such instabilities of organic electronic materials. Here, an overview is provided of the strategies developed for environmentally robust organic electronics to overcome the detrimental effects of various critical factors such as oxygen, water, chemicals, heat, and light. Additionally, molecular design approaches to π-conjugated small molecules and polymers that are highly stable under ambient and harsh conditions are explored; such materials will circumvent the need for encapsulation and provide a greater degree of freedom using simple solution-based device-fabrication techniques. Applications that are made possible through these strategies are highlighted. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Teaching Chemistry with Electron Density Models

    Science.gov (United States)

    Shusterman, Gwendolyn P.; Shusterman, Alan J.

    1997-07-01

    Linus Pauling once said that a topic must satisfy two criteria before it can be taught to students. First, students must be able to assimilate the topic within a reasonable amount of time. Second, the topic must be relevant to the educational needs and interests of the students. Unfortunately, the standard general chemistry textbook presentation of "electronic structure theory", set as it is in the language of molecular orbitals, has a difficult time satisfying either criterion. Many of the quantum mechanical aspects of molecular orbitals are too difficult for most beginning students to appreciate, much less master, and the few applications that are presented in the typical textbook are too limited in scope to excite much student interest. This article describes a powerful new method for teaching students about electronic structure and its relevance to chemical phenomena. This method, which we have developed and used for several years in general chemistry (G.P.S.) and organic chemistry (A.J.S.) courses, relies on computer-generated three-dimensional models of electron density distributions, and largely satisfies Pauling's two criteria. Students find electron density models easy to understand and use, and because these models are easily applied to a broad range of topics, they successfully convey to students the importance of electronic structure. In addition, when students finally learn about orbital concepts they are better prepared because they already have a well-developed three-dimensional picture of electronic structure to fall back on. We note in this regard that the types of models we use have found widespread, rigorous application in chemical research (1, 2), so students who understand and use electron density models do not need to "unlearn" anything before progressing to more advanced theories.

  14. Exact diagonalization library for quantum electron models

    Science.gov (United States)

    Iskakov, Sergei; Danilov, Michael

    2018-04-01

    We present an exact diagonalization C++ template library (EDLib) for solving quantum electron models, including the single-band finite Hubbard cluster and the multi-orbital impurity Anderson model. The observables that can be computed using EDLib are single particle Green's functions and spin-spin correlation functions. This code provides three different types of Hamiltonian matrix storage that can be chosen based on the model.

  15. New Approach to Total Dose Specification for Spacecraft Electronics

    Science.gov (United States)

    Xapsos, Michael

    2017-01-01

    Variability of the space radiation environment is investigated with regard to total dose specification for spacecraft electronics. It is shown to have a significant impact. A new approach is developed for total dose requirements that replaces the radiation design margin concept with failure probability during a mission.

  16. Regional 4-D modeling of the ionospheric electron density

    Science.gov (United States)

    Schmidt, M.; Bilitza, D.; Shum, C. K.; Zeilhofer, C.

    2008-08-01

    The knowledge of the electron density is the key point in correcting ionospheric delays of electromagnetic measurements and in studying the ionosphere. During the last decade GNSS, in particular GPS, has become a promising tool for monitoring the total electron content (TEC), i.e., the integral of the electron density along the ray-path between the transmitting satellite and the receiver. Hence, geometry-free GNSS measurements provide informations on the electron density, which is basically a four-dimensional function depending on spatial position and time. In addition, these GNSS measurements can be combined with other available data including nadir, over-ocean TEC observations from dual-frequency radar altimetry (T/P, JASON, ENVISAT), and TECs from GPS-LEO occultation systems (e.g., FORMOSAT-3/COSMIC, CHAMP) with heterogeneous sampling and accuracy. In this paper, we present different multi-dimensional approaches for modeling spatio-temporal variations of the ionospheric electron density. To be more specific, we split the target function into a reference part, computed from the International Reference Ionosphere (IRI), and an unknown correction term. Due to the localizing feature of B-spline functions we apply tensor-product spline expansions to model the correction term in a certain multi-dimensional region either completely or partly. Furthermore, the multi-resolution representation derived from wavelet analysis allows monitoring the ionosphere at different resolutions levels. For demonstration we apply three approaches to electron density data over South America.

  17. Multiple scattering approach to the vibrational excitation of molecules by slow electrons

    International Nuclear Information System (INIS)

    Drukarev, G.

    1976-01-01

    Another approach to the problem of vibrational excitation of homonuclear two-atomic molecules by slow electrons possibly accompanied by rotational transitions is presented based on the picture of multiple scattering of an electron inside the molecule. The scattering of two fixed centers in the zero range potential model is considered. The results indicate that the multiple scattering determines the order of magnitude of the vibrational excitation cross sections in the energy region under consideration even if the zero range potential model is used. Also the connection between the multiple scattering approach and quasi-stationary molecular ion picture is established. 9 refs

  18. Electronic structure of a striped nickelate studied by the exact exchange for correlated electrons (EECE) approach

    KAUST Repository

    Schwingenschlögl, Udo

    2009-12-01

    Motivated by a RIXS study of Wakimoto, et al.(Phys. Rev. Lett., 102 (2009) 157001) we use density functional theory to analyze the magnetic order in the nickelate La5/3Sr1/3NiO4 and the details of its crystal and electronic structure. We compare the generalized gradient approximation to the hybrid functional approach of exact exchange for correlated electrons (EECE). In contrast to the former, the latter reproduces the insulating state of the compound and the midgap states. The EECE approach, in general, appears to be appropriate for describing stripe phases in systems with orbital degrees of freedom. Copyright © EPLA, 2009.

  19. Neo-Institutional Approach to the Study of Electronic Government

    Directory of Open Access Journals (Sweden)

    Yan I. Vaslavskiy

    2016-01-01

    Full Text Available The article is devoted to the neo-institutional approach as a methodological basis in the study of electronic government. In this article substantiates the choice of neo-institutional approach to the study of the processes of implementation of information and communication technologies in the activity of state institutions, analyzes the differences of neoinstitutionalism from traditional institutional approach, considers the features of the different directions of neo-institutionalism, namely sociological, historical and rational choice theory. Attention is paid to the reasons for the renewed interest in political institutions in political science. The article emphasizes the importance of considering the electronic government as an institution, and the conditions for its implementation in the Russian political system as the institutional environment. The authors pay special attention to the variety of sociological neo-institutionalism, used, in addition to political science in sociology of organizations. The article substantiates the value of using sociological institutionalism to explore the electronic government based on a comparative analysis of e-government projects in Russia and abroad and explores its heuristic capabilities. It examines the impact of the system of norms and values of the institutional environment on the processes of formation and development of electronic government in Russia. The research capacity of this theory is due to the fact that it allows us to trace the reasons for copying and replication of inefficient practices and organizational and management schemes, to identify the factors impeding innovation use by the state of electronic interaction technologies. It is emphasized that the use of the theory of institutional isomorphism is useful in the sphere of implementation of electronic technologies, in which a key role play pluralism, horizontal managerial communication, inter-agency coordination.

  20. Orbital approach to the electronic structure of solids

    CERN Document Server

    Canadell, Enric; Iung, Christophe

    2012-01-01

    This book provides an intuitive yet sound understanding of how structure and properties of solids may be related. The natural link is provided by the band theory approach to the electronic structure of solids. The chemically insightful concept of orbital interaction and the essential machinery of band theory are used throughout the book to build links between the crystal and electronic structure of periodic systems. In such a way, it is shown how important tools for understandingproperties of solids like the density of states, the Fermi surface etc. can be qualitatively sketched and used to ei

  1. Ionospheric topside models compared with experimental electron density profiles

    Directory of Open Access Journals (Sweden)

    S. M. Radicella

    2005-06-01

    Full Text Available Recently an increasing number of topside electron density profiles has been made available to the scientific community on the Internet. These data are important for ionospheric modeling purposes, since the experimental information on the electron density above the ionosphere maximum of ionization is very scarce. The present work compares NeQuick and IRI models with the topside electron density profiles available in the databases of the ISIS2, IK19 and Cosmos 1809 satellites. Experimental electron content from the F2 peak up to satellite height and electron densities at fixed heights above the peak have been compared under a wide range of different conditions. The analysis performed points out the behavior of the models and the improvements needed to be assessed to have a better reproduction of the experimental results. NeQuick topside is a modified Epstein layer, with thickness parameter determined by an empirical relation. It appears that its performance is strongly affected by this parameter, indicating the need for improvements of its formulation. IRI topside is based on Booker's approach to consider two parts with constant height gradients. It appears that this formulation leads to an overestimation of the electron density in the upper part of the profiles, and overestimation of TEC.

  2. Path integral approach to electron scattering in classical electromagnetic potential

    International Nuclear Information System (INIS)

    Xu Chuang; Feng Feng; Li Ying-Jun

    2016-01-01

    As is known to all, the electron scattering in classical electromagnetic potential is one of the most widespread applications of quantum theory. Nevertheless, many discussions about electron scattering are based upon single-particle Schrodinger equation or Dirac equation in quantum mechanics rather than the method of quantum field theory. In this paper, by using the path integral approach of quantum field theory, we perturbatively evaluate the scattering amplitude up to the second order for the electron scattering by the classical electromagnetic potential. The results we derive are convenient to apply to all sorts of potential forms. Furthermore, by means of the obtained results, we give explicit calculations for the one-dimensional electric potential. (paper)

  3. Visualized attribute analysis approach for characterization and quantification of rice taste flavor using electronic tongue

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Lin; Hu, Xianqiao [Rice Product Quality Supervision and Inspection Center, Ministry of Agriculture, China National Rice Research Institute, Hangzhou 310006 (China); Tian, Shiyi; Deng, Shaoping [College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310035 (China); Zhu, Zhiwei, E-mail: 615834652@qq.com [Rice Product Quality Supervision and Inspection Center, Ministry of Agriculture, China National Rice Research Institute, Hangzhou 310006 (China)

    2016-05-05

    This paper deals with a novel visualized attributive analysis approach for characterization and quantification of rice taste flavor attributes (softness, stickiness, sweetness and aroma) employing a multifrequency large-amplitude pulse voltammetric electronic tongue. Data preprocessing methods including Principal Component Analysis (PCA) and Fast Fourier Transform (FFT) were provided. An attribute characterization graph was represented for visualization of the interactive response in which each attribute responded by specific electrodes and frequencies. The model was trained using signal data from electronic tongue and attribute scores from artificial evaluation. The correlation coefficients for all attributes were over 0.9, resulting in good predictive ability of attributive analysis model preprocessed by FFT. This approach extracted more effective information about linear relationship between electronic tongue and taste flavor attribute. Results indicated that this approach can accurately quantify taste flavor attributes, and can be an efficient tool for data processing in a voltammetric electronic tongue system. - Graphical abstract: Schematic process for visualized attributive analysis approach using multifrequency large-amplitude pulse voltammetric electronic tongue for determination of rice taste flavor attribute. (a) sample; (b) sensors in electronic tongue; (c) excitation voltage program and response current signal from MLAPS; (d) similarity data matrix by data preprocessing and similarity extraction; (e) feature data matrix of attribute; (f) attribute characterization graph; (g) attribute scores predicted by the model. - Highlights: • Multifrequency large-amplitude pulse voltammetric electronic tongue was used. • A visualized attributive analysis approach was created as an efficient tool for data processing. • Rice taste flavor attribute was determined and predicted. • The attribute characterization graph was represented for visualization of the

  4. Cyber Physical Systems Approach to Power Electronics Education

    Directory of Open Access Journals (Sweden)

    Marko Vekić

    2012-12-01

    Full Text Available This paper proposes a Cyber Physical Approach (CPS to power electronics (PE education where all aspects of PE technology from circuit topology to the implementation of real time control code on a microprocessor are dealt with as an inseparable whole, and only the system complexity is increased during the course of instruction. This approach is now made practical thanks to the affordable and unrestricted access to high-power PE laboratory infrastructure (PE laboratory in a box in the form of high-fidelity digital PE emulators with 1us calculation time step and latency.

  5. An effective approach for choosing an electronic health record.

    Science.gov (United States)

    Rowley, Robert

    2009-01-01

    With government stimulus money becoming available to encourage healthcare facilities to adopt electronic health record (EHR) systems, the decision to move forward with implementing an EHR system has taken on an urgency not previously seen. The EHR landscape is evolving rapidly and the underlying technology platform is becoming increasingly interconnected. One must make sure that an EHR decision does not lock oneself into technology obsolescence. The best approach for evaluating an EHR is on the basis of:usability, interoperability, and affordability.

  6. Materials and processing approaches for foundry-compatible transient electronics

    Science.gov (United States)

    Chang, Jan-Kai; Fang, Hui; Bower, Christopher A.; Song, Enming; Yu, Xinge; Rogers, John A.

    2017-07-01

    Foundry-based routes to transient silicon electronic devices have the potential to serve as the manufacturing basis for “green” electronic devices, biodegradable implants, hardware secure data storage systems, and unrecoverable remote devices. This article introduces materials and processing approaches that enable state-of-the-art silicon complementary metal-oxide-semiconductor (CMOS) foundries to be leveraged for high-performance, water-soluble forms of electronics. The key elements are (i) collections of biodegradable electronic materials (e.g., silicon, tungsten, silicon nitride, silicon dioxide) and device architectures that are compatible with manufacturing procedures currently used in the integrated circuit industry, (ii) release schemes and transfer printing methods for integration of multiple ultrathin components formed in this way onto biodegradable polymer substrates, and (iii) planarization and metallization techniques to yield interconnected and fully functional systems. Various CMOS devices and circuit elements created in this fashion and detailed measurements of their electrical characteristics highlight the capabilities. Accelerated dissolution studies in aqueous environments reveal the chemical kinetics associated with the underlying transient behaviors. The results demonstrate the technical feasibility for using foundry-based routes to sophisticated forms of transient electronic devices, with functional capabilities and cost structures that could support diverse applications in the biomedical, military, industrial, and consumer industries.

  7. Electronic excitation of atoms and molecules by electron impact in a linear algebraic, separable potential approach

    International Nuclear Information System (INIS)

    Collins, L.A.; Schneider, B.I.

    1984-01-01

    The linear algebraic, separable potential approach is applied to the electronic excitation of atoms and molecules by electron impact. By representing the exchange and off-diagonal direct terms on a basis, the standard set of coupled inelastic equations is reduced to a set of elastic inhomogeneous equations. The procedure greatly simplifies the formulation by allowing a large portion of the problem to be handled by standard bound-state techniques and by greatly reducing the order of the scattering equations that must be solved. Application is made to the excitation of atomic hydrogen in the three-state close-coupling (1s, 2s, 2p) approximation. (author)

  8. Ontological modeling of electronic health information exchange.

    Science.gov (United States)

    McMurray, J; Zhu, L; McKillop, I; Chen, H

    2015-08-01

    Investments of resources to purposively improve the movement of information between health system providers are currently made with imperfect information. No inventories of system-level electronic health information flows currently exist, nor do measures of inter-organizational electronic information exchange. Using Protégé 4, an open-source OWL Web ontology language editor and knowledge-based framework, we formalized a model that decomposes inter-organizational electronic health information flow into derivative concepts such as diversity, breadth, volume, structure, standardization and connectivity. The ontology was populated with data from a regional health system and the flows were measured. Individual instance's properties were inferred from their class associations as determined by their data and object property rules. It was also possible to visualize interoperability activity for regional analysis and planning purposes. A property called Impact was created from the total number of patients or clients that a health entity in the region served in a year, and the total number of health service providers or organizations with whom it exchanged information in support of clinical decision-making, diagnosis or treatment. Identifying providers with a high Impact but low Interoperability score could assist planners and policy-makers to optimize technology investments intended to electronically share patient information across the continuum of care. Finally, we demonstrated how linked ontologies were used to identify logical inconsistencies in self-reported data for the study. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. HEDR modeling approach: Revision 1

    International Nuclear Information System (INIS)

    Shipler, D.B.; Napier, B.A.

    1994-05-01

    This report is a revision of the previous Hanford Environmental Dose Reconstruction (HEDR) Project modeling approach report. This revised report describes the methods used in performing scoping studies and estimating final radiation doses to real and representative individuals who lived in the vicinity of the Hanford Site. The scoping studies and dose estimates pertain to various environmental pathways during various periods of time. The original report discussed the concepts under consideration in 1991. The methods for estimating dose have been refined as understanding of existing data, the scope of pathways, and the magnitudes of dose estimates were evaluated through scoping studies

  10. HEDR modeling approach: Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Shipler, D.B.; Napier, B.A.

    1994-05-01

    This report is a revision of the previous Hanford Environmental Dose Reconstruction (HEDR) Project modeling approach report. This revised report describes the methods used in performing scoping studies and estimating final radiation doses to real and representative individuals who lived in the vicinity of the Hanford Site. The scoping studies and dose estimates pertain to various environmental pathways during various periods of time. The original report discussed the concepts under consideration in 1991. The methods for estimating dose have been refined as understanding of existing data, the scope of pathways, and the magnitudes of dose estimates were evaluated through scoping studies.

  11. A Model-Driven Approach to e-Course Management

    Science.gov (United States)

    Savic, Goran; Segedinac, Milan; Milenkovic, Dušica; Hrin, Tamara; Segedinac, Mirjana

    2018-01-01

    This paper presents research on using a model-driven approach to the development and management of electronic courses. We propose a course management system which stores a course model represented as distinct machine-readable components containing domain knowledge of different course aspects. Based on this formally defined platform-independent…

  12. Modeling Approaches in Planetary Seismology

    Science.gov (United States)

    Weber, Renee; Knapmeyer, Martin; Panning, Mark; Schmerr, Nick

    2014-01-01

    Of the many geophysical means that can be used to probe a planet's interior, seismology remains the most direct. Given that the seismic data gathered on the Moon over 40 years ago revolutionized our understanding of the Moon and are still being used today to produce new insight into the state of the lunar interior, it is no wonder that many future missions, both real and conceptual, plan to take seismometers to other planets. To best facilitate the return of high-quality data from these instruments, as well as to further our understanding of the dynamic processes that modify a planet's interior, various modeling approaches are used to quantify parameters such as the amount and distribution of seismicity, tidal deformation, and seismic structure on and of the terrestrial planets. In addition, recent advances in wavefield modeling have permitted a renewed look at seismic energy transmission and the effects of attenuation and scattering, as well as the presence and effect of a core, on recorded seismograms. In this chapter, we will review these approaches.

  13. Computational electronics semiclassical and quantum device modeling and simulation

    CERN Document Server

    Vasileska, Dragica; Klimeck, Gerhard

    2010-01-01

    Starting with the simplest semiclassical approaches and ending with the description of complex fully quantum-mechanical methods for quantum transport analysis of state-of-the-art devices, Computational Electronics: Semiclassical and Quantum Device Modeling and Simulation provides a comprehensive overview of the essential techniques and methods for effectively analyzing transport in semiconductor devices. With the transistor reaching its limits and new device designs and paradigms of operation being explored, this timely resource delivers the simulation methods needed to properly model state-of

  14. Analysis of operating model of electronic invoice colombian Colombian electronic billing analysis of the operational model

    Directory of Open Access Journals (Sweden)

    Sérgio Roberto da Silva

    2016-06-01

    Full Text Available Colombia has been one of the first countries to introduce electronic billing process on a voluntary basis, from a traditional to a digital version. In this context, the article analyzes the electronic billing process implemented in Colombia and the advantages. Methodological research is applied, qualitative, descriptive and documentary; where the regulatory framework and the conceptualization of the model is identified; the process of adoption of electronic billing is analyzed, and finally the advantages and disadvantages of its implementation is analyzed. The findings indicate that the model applied in Colombia to issue an electronic billing in sending and receiving process, is not complex, but it requires a small adequate infrastructure and trained personnel to reach all sectors, especially the micro and business which is the largest business network in the country.

  15. Branding approach and valuation models

    Directory of Open Access Journals (Sweden)

    Mamula Tatjana

    2006-01-01

    Full Text Available Much of the skill of marketing and branding nowadays is concerned with building equity for products whose characteristics, pricing, distribution and availability are really quite close to each other. Brands allow the consumer to shop with confidence. The real power of successful brands is that they meet the expectations of those that buy them or, to put it another way, they represent a promise kept. As such they are a contract between a seller and a buyer: if the seller keeps to its side of the bargain, the buyer will be satisfied; if not, the buyer will in future look elsewhere. Understanding consumer perceptions and associations is an important first step to understanding brand preferences and choices. In this paper, we discuss different models to measure value of brand according to couple of well known approaches according to request by companies. We rely upon several empirical examples.

  16. Problems and Projects Based Approach For Analog Electronic Circuits' Course

    Directory of Open Access Journals (Sweden)

    Mustapha Rafaf

    2009-04-01

    Full Text Available New educational methods and approaches are recently introduced and implemented at several North American and European universities using Problems and Projects Based Approach (PPBA. The PPBA employs a teaching technique based mostly on competences/skills rather than only on knowledge. This method has been implemented and proven by several pedagogical instructors and authors at several educational institutions. This approach is used at different disciplines such as medicine, biology, engineering and many others. It has the advantage to improve the student's skills and the knowledge retention rate, and reflects the 21st century industrial/company needs and demands. Before implementing this approach to a course, a good resources preparation and planning is needed upfront by the responsible or instructor of the course to achieve the course and students related objectives. This paper presents the preparation, the generated documentation and the implementation of a pilot project utilizing PPBA education for a second year undergraduate electronic course over a complete semester, and for two different class groups (morning and evening groups. The outcome of this project (achieved goals, observed difficulties and lessons learned is presented based on different tools such as students 'in class' communication and feedback, different course evaluation forms and the professor/instructor feedback. Resources, challenges, difficulties and recommendations are also assessed and presented. The impact, the effect and the results (during and at the end of the academic fall session of the PPBA on students and instructor are discussed, validated, managed and communicated to help other instructor in taking appropriate approach decisions with respect to this new educational approach compared to the classical one.

  17. Evaluation of electronic polarization energy in oligoacene molecular crystals using the solvated supermolecular approach.

    Science.gov (United States)

    Xu, Tao; Wang, Wenliang; Yin, Shiwei; Wang, Yun

    2017-06-07

    The solvated supermolecular approach, i.e., block-localized wave function coupled with polarizable continuum model (BLW/PCM), was proposed to calculate molecular ionization potential (IP), electron affinity (EA) in the solid phase, and related electronic polarization. Via the calculations of a solvated supermolecule (5M), including four closest molecules, BLW/PCM overcomes the limitation in the calculation for the monomer PCM, that is, nearly same electronic polarization for cation (P + ) and anion (P - ). The solvated supermolecular approach successfully described asymmetric behaviors of P + and P - for oligoacene crystals. In addition, we also compared two charge-localized methods, i.e., BLW and constrained density functional theory (CDFT), to calculate the molecular IP and EA in supermolecules with/without PCM. Our results demonstrate that both the BLW and CDFT correctly estimate the EA and IP values in the gas phase cluster, whereas CDFT/PCM fails to evaluate the P - value of the bulk system.

  18. Model based design of electronic throttle control

    Science.gov (United States)

    Cherian, Fenin; Ranjan, Ashish; Bhowmick, Pathikrit; Rammohan, A.

    2017-11-01

    With the advent of torque based Engine Management Systems, the precise control and robust performance of the throttle body becomes a key factor in the overall performance of the vehicle. Electronic Throttle Control provides benefits such as improved air-fuel ratio for improving the vehicle performance and lower exhausts emissions to meet the stringent emission norms. Modern vehicles facilitate various features such as Cruise Control, Traction Control, Electronic Stability Program and Pre-crash systems. These systems require control over engine power without driver intervention, which is not possible with conventional mechanical throttle system. Thus these systems are integrated to function with the electronic throttle control. However, due to inherent non-linearities in the throttle body, the control becomes a difficult task. In order to eliminate the influence of this hysteresis at the initial operation of the butterfly valve, a control to compensate the shortage must be added to the duty required for starting throttle operation when the initial operation is detected. Therefore, a lot of work is being done in this field to incorporate the various nonlinearities to achieve robust control. In our present work, the ETB was tested to verify the working of the system. Calibration of the TPS sensors was carried out in order to acquire accurate throttle opening angle. The response of the calibrated system was then plotted against a step input signal. A linear model of the ETB was prepared using Simulink and its response was compared with the experimental data to find out the initial deviation of the model from the actual system. To reduce this deviation, non-linearities from existing literature were introduced to the system and a response analysis was performed to check the deviation from the actual system. Based on this investigation, an introduction of a new nonlinearity parameter can be used in future to reduce the deviation further making the control of the ETB more

  19. Development and application of a 2-electron reduced density matrix approach to electron transport via molecular junctions

    Science.gov (United States)

    Hoy, Erik P.; Mazziotti, David A.; Seideman, Tamar

    2017-11-01

    Can an electronic device be constructed using only a single molecule? Since this question was first asked by Aviram and Ratner in the 1970s [Chem. Phys. Lett. 29, 277 (1974)], the field of molecular electronics has exploded with significant experimental advancements in the understanding of the charge transport properties of single molecule devices. Efforts to explain the results of these experiments and identify promising new candidate molecules for molecular devices have led to the development of numerous new theoretical methods including the current standard theoretical approach for studying single molecule charge transport, i.e., the non-equilibrium Green's function formalism (NEGF). By pairing this formalism with density functional theory (DFT), a wide variety of transport problems in molecular junctions have been successfully treated. For some systems though, the conductance and current-voltage curves predicted by common DFT functionals can be several orders of magnitude above experimental results. In addition, since density functional theory relies on approximations to the exact exchange-correlation functional, the predicted transport properties can show significant variation depending on the functional chosen. As a first step to addressing this issue, the authors have replaced density functional theory in the NEGF formalism with a 2-electron reduced density matrix (2-RDM) method, creating a new approach known as the NEGF-RDM method. 2-RDM methods provide a more accurate description of electron correlation compared to density functional theory, and they have lower computational scaling compared to wavefunction based methods of similar accuracy. Additionally, 2-RDM methods are capable of capturing static electron correlation which is untreatable by existing NEGF-DFT methods. When studying dithiol alkane chains and dithiol benzene in model junctions, the authors found that the NEGF-RDM predicts conductances and currents that are 1-2 orders of magnitude below

  20. Putting structure into context: fitting of atomic models into electron microscopic and electron tomographic reconstructions.

    Science.gov (United States)

    Volkmann, Niels

    2012-02-01

    A complete understanding of complex dynamic cellular processes such as cell migration or cell adhesion requires the integration of atomic level structural information into the larger cellular context. While direct atomic-level information at the cellular level remains inaccessible, electron microscopy, electron tomography and their associated computational image processing approaches have now matured to a point where sub-cellular structures can be imaged in three dimensions at the nanometer scale. Atomic-resolution information obtained by other means can be combined with this data to obtain three-dimensional models of large macromolecular assemblies in their cellular context. This article summarizes some recent advances in this field. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Power electronic converters modeling and control with case studies

    CERN Document Server

    Bacha, Seddik; Bratcu, Antoneta Iuliana

    2014-01-01

    Modern power electronic converters are involved in a very broad spectrum of applications: switched-mode power supplies, electrical-machine-motion-control, active power filters, distributed power generation, flexible AC transmission systems, renewable energy conversion systems and vehicular technology, among them. Power Electronics Converters Modeling and Control teaches the reader how to analyze and model the behavior of converters and so to improve their design and control. Dealing with a set of confirmed algorithms specifically developed for use with power converters, this text is in two parts: models and control methods. The first is a detailed exposition of the most usual power converter models: ·        switched and averaged models; ·        small/large-signal models; and ·        time/frequency models. The second focuses on three groups of control methods: ·        linear control approaches normally associated with power converters; ·        resonant controllers b...

  2. Inverse Problem Approach for the Alignment of Electron Tomographic Series

    International Nuclear Information System (INIS)

    Tran, V.D.; Moreaud, M.; Thiebaut, E.; Denis, L.; Becker, J.M.

    2014-01-01

    In the refining industry, morphological measurements of particles have become an essential part in the characterization catalyst supports. Through these parameters, one can infer the specific physico-chemical properties of the studied materials. One of the main acquisition techniques is electron tomography (or nano-tomography). 3D volumes are reconstructed from sets of projections from different angles made by a Transmission Electron Microscope (TEM). This technique provides a real three-dimensional information at the nano-metric scale. A major issue in this method is the misalignment of the projections that contributes to the reconstruction. The current alignment techniques usually employ fiducial markers such as gold particles for a correct alignment of the images. When the use of markers is not possible, the correlation between adjacent projections is used to align them. However, this method sometimes fails. In this paper, we propose a new method based on the inverse problem approach where a certain criterion is minimized using a variant of the Nelder and Mead simplex algorithm. The proposed approach is composed of two steps. The first step consists of an initial alignment process, which relies on the minimization of a cost function based on robust statistics measuring the similarity of a projection to its previous projections in the series. It reduces strong shifts resulting from the acquisition between successive projections. In the second step, the pre-registered projections are used to initialize an iterative alignment-refinement process which alternates between (i) volume reconstructions and (ii) registrations of measured projections onto simulated projections computed from the volume reconstructed in (i). At the end of this process, we have a correct reconstruction of the volume, the projections being correctly aligned. Our method is tested on simulated data and shown to estimate accurately the translation, rotation and scale of arbitrary transforms. We

  3. A cloud-based approach for interoperable electronic health records (EHRs).

    Science.gov (United States)

    Bahga, Arshdeep; Madisetti, Vijay K

    2013-09-01

    We present a cloud-based approach for the design of interoperable electronic health record (EHR) systems. Cloud computing environments provide several benefits to all the stakeholders in the healthcare ecosystem (patients, providers, payers, etc.). Lack of data interoperability standards and solutions has been a major obstacle in the exchange of healthcare data between different stakeholders. We propose an EHR system - cloud health information systems technology architecture (CHISTAR) that achieves semantic interoperability through the use of a generic design methodology which uses a reference model that defines a general purpose set of data structures and an archetype model that defines the clinical data attributes. CHISTAR application components are designed using the cloud component model approach that comprises of loosely coupled components that communicate asynchronously. In this paper, we describe the high-level design of CHISTAR and the approaches for semantic interoperability, data integration, and security.

  4. Models for the transport of low energy electrons in water and the yield of hydrated electrons at early times

    International Nuclear Information System (INIS)

    Brenner, D.J.; Miller, J.H.; Ritchie, R.H.; Bichsel, H.

    1985-01-01

    An insulator model with four experimental energy bands was used to fit the optical properties of liquid water and to extend these data to non-zero momentum transfer. Inelastic mean free paths derived from this dielectric response function provided the basic information necessary to degrade high energy electrons to the subexcitation energy domain. Two approaches for the transport of subexcitation electrons were investigated. (i) Gas phase cross sections were used to degrade subexcitation electrons to thermal energy and the thermalization lengths were scaled to unit density. (ii) Thermalization lengths were estimated by age-diffusion theory with a stopping power deduced from the data on liquid water and transport cross sections derived from elastic scattering in water vapor. Theoretical ranges were compared to recent experimental results. A stochastic model was used to calculate the rapid diffusion and reaction of hydrated electrons with other radiolysis products. The sensitivity of the calculated yields to the model assumptions and comparison with experimental data are discussed

  5. A Bayesian approach to model uncertainty

    International Nuclear Information System (INIS)

    Buslik, A.

    1994-01-01

    A Bayesian approach to model uncertainty is taken. For the case of a finite number of alternative models, the model uncertainty is equivalent to parameter uncertainty. A derivation based on Savage's partition problem is given

  6. Real-Time Robust Adaptive Modeling and Scheduling for an Electronic Commerce Server

    Science.gov (United States)

    Du, Bing; Ruan, Chun

    With the increasing importance and pervasiveness of Internet services, it is becoming a challenge for the proliferation of electronic commerce services to provide performance guarantees under extreme overload. This paper describes a real-time optimization modeling and scheduling approach for performance guarantee of electronic commerce servers. We show that an electronic commerce server may be simulated as a multi-tank system. A robust adaptive server model is subject to unknown additive load disturbances and uncertain model matching. Overload control techniques are based on adaptive admission control to achieve timing guarantees. We evaluate the performance of the model using a complex simulation that is subjected to varying model parameters and massive overload.

  7. Model Order Reduction for Electronic Circuits:

    DEFF Research Database (Denmark)

    Hjorth, Poul G.; Shontz, Suzanne

    Electronic circuits are ubiquitous; they are used in numerous industries including: the semiconductor, communication, robotics, auto, and music industries (among many others). As products become more and more complicated, their electronic circuits also grow in size and complexity. This increased...

  8. A Model for an Electronic Information Marketplace

    Directory of Open Access Journals (Sweden)

    Wei Ge

    2005-11-01

    Full Text Available As the information content on the Internet increases, the task of locating desired information and assessing its quality becomes increasingly difficult. This development causes users to be more willing to pay for information that is focused on specific issues, verifiable, and available upon request. Thus, the nature of the Internet opens up the opportunity for information trading. In this context, the Internet cannot only be used to close the transaction, but also to deliver the product - desired information - to the user. Early attempts to implement such business models have fallen short of expectations. In this paper, we discuss the limitations of such practices and present a modified business model for information trading, which uses a reverse auction approach together with a multiple-buyer price discovery process

  9. On the Computation of Secondary Electron Emission Models

    OpenAIRE

    Clerc, Sebastien; Dennison, JR; Hoffmann, Ryan; Abbott, Jonathon

    2006-01-01

    Secondary electron emission is a critical contributor to the charge particle current balance in spacecraft charging. Spacecraft charging simulation codes use a parameterized expression for the secondary electron (SE) yield delta(Eo) as a function of the incident electron energy Eo. Simple three-step physics models of the electron penetration, transport, and emission from a solid are typically expressed in terms of the incident electron penetration depth at normal incidence R(Eo) and the mean ...

  10. A Model for Teaching Electronic Commerce Students

    Directory of Open Access Journals (Sweden)

    Howard C. Woodard

    2002-10-01

    Full Text Available The teaching of information technology in an ever-changing world at universities presents a challenge. Are courses taught as concepts, while ignoring hands-on courses, leaving the hands-on classes to the technical colleges or trade schools? Does this produce the best employees for industry or give students the knowledge and skills necessary to function in a high-tech world? At GeorgiaCollege & StateUniversity (GC&SU a model was developed that combines both concepts and practical hands-on skill to meet this challenge. Using this model, a program was developed that consists of classroom lecture of concepts as well as practical hands-on exercises for mastering the knowledge and developing the skills necessary to succeed in the high-tech world of electronic commerce. The students become productive day one of a new job assignment. This solves the problem of students having the "book knowledge" but not knowing how to apply what has been learned.

  11. Model of electron capture in low-temperature glasses

    International Nuclear Information System (INIS)

    Bartczak, W.M.; Swiatla, D.; Kroh, J.

    1983-01-01

    The new model of electron capture by a statistical variety of traps in glassy matrices is proposed. The electron capture is interpreted as the radiationless transition (assisted by multiphonon emission) of the mobile electron to the localized state in the trap. The conception of 'unfair' and 'fair' traps is introduced. The 'unfair' trap captures the mobile electron by the shallow excited state. In contrast, the 'fair' trap captures the electron by the ground state. The model calculations of the statistical distributions of the occupied electron traps are presented and discussed with respect to experimental results. (author)

  12. Nicotine and Cotinine Exposure from Electronic Cigarettes: A Population Approach

    Science.gov (United States)

    de Mendizábal, Nieves Vélez; Jones, David R.; Jahn, Andy; Bies, Robert R.; Brown, Joshua W.

    2015-01-01

    Background and Objectives Electronic cigarettes (e-cigarettes) are a recent technology that has gained rapid acceptance. Still, little is known about them in terms of safety and effectiveness. A basic question is how effectively they deliver nicotine, however the literature is surprisingly unclear on this point. Here, a population pharmacokinetic (PK) model was developed for nicotine and its major metabolite cotinine with the aim to provide a reliable framework for the simulation of nicotine and cotinine concentrations over time, based solely on inhalation airflow recordings and individual covariates (i.e. weight and breath carbon monoxide CO levels). Methods This study included 10 adults self-identified as heavy smokers (at least one pack per day). Plasma nicotine and cotinine concentrations were measured at regular 10-minute intervals for 90 minutes while human subjects inhaled nicotine vapor from a modified e-cigarette. Airflow measurements were recorded every 200 milliseconds throughout the session. A population PK model for nicotine and cotinine was developed based on previously published PK parameters and the airflow recordings. All the analyses were performed with the nonlinear mixed-effect modelling software NONMEM 7.2. Results The results show that e-cigarettes deliver nicotine effectively, although the pharmacokinetic profiles are lower than those achieved with regular cigarettes. Our PK model effectively predicts plasma nicotine and cotinine concentrations from the inhalation volume, and initial breath CO. Conclusion E-cigarettes are effective at delivering nicotine. This new PK model of e-cigarette usage might be used for pharmacodynamic analysis where the PK profiles are not available. PMID:25503588

  13. Reliable modeling of the electronic spectra of realistic uranium complexes

    Science.gov (United States)

    Tecmer, Paweł; Govind, Niranjan; Kowalski, Karol; de Jong, Wibe A.; Visscher, Lucas

    2013-07-01

    We present an EOMCCSD (equation of motion coupled cluster with singles and doubles) study of excited states of the small [UO2]2+ and [UO2]+ model systems as well as the larger UVIO2(saldien) complex. In addition, the triples contribution within the EOMCCSDT and CR-EOMCCSD(T) (completely renormalized EOMCCSD with non-iterative triples) approaches for the [UO2]2+ and [UO2]+ systems as well as the active-space variant of the CR-EOMCCSD(T) method—CR-EOMCCSd(t)—for the UVIO2(saldien) molecule are investigated. The coupled cluster data were employed as benchmark to choose the "best" appropriate exchange-correlation functional for subsequent time-dependent density functional (TD-DFT) studies on the transition energies for closed-shell species. Furthermore, the influence of the saldien ligands on the electronic structure and excitation energies of the [UO2]+ molecule is discussed. The electronic excitations as well as their oscillator dipole strengths modeled with TD-DFT approach using the CAM-B3LYP exchange-correlation functional for the [UVO2(saldien)]- with explicit inclusion of two dimethyl sulfoxide molecules are in good agreement with the experimental data of Takao et al. [Inorg. Chem. 49, 2349 (2010), 10.1021/ic902225f].

  14. Slow electron energy balance for hybrid models of direct-current glow discharges

    Science.gov (United States)

    Eliseev, S. I.; Bogdanov, E. A.; Kudryavtsev, A. A.

    2017-09-01

    In this paper, we present the formulation of slow electron energy balance for hybrid models of direct current (DC) glow discharge. Electrons originating from non-local ionization (secondary) contribute significantly to the energy balance of slow electrons. An approach towards calculating effective energy brought by a secondary electron to the group of slow electrons by means of Coulomb collisions is suggested. The value of effective energy shows a considerable dependence on external parameters of a discharge, such as gas pressure, type, and geometric parameters. The slow electron energy balance was implemented into a simple hybrid model that uses analytical formulation for the description of non-local ionization by fast electrons. Simulations of short (without positive column) DC glow discharge in argon are carried out for a range of gas pressures. Comparison with experimental data showed generally good agreement in terms of current-voltage characteristics, electron density, and electron temperature. Simulations also capture the trend of increasing electron density with decreasing pressure observed in the experiment. Analysis shows that for considered conditions, the product of maximum electron density ne and electron temperature Te in negative glow is independent of gas pressure and depends on the gas type, cathode material, and discharge current. Decreasing gas pressure reduces the heating rate of slow electrons during Coulomb collisions with secondary electrons, which leads to lower values of Te and, in turn, higher maximum ne.

  15. Research on lightning stroke model and characteristics of electronic transformer

    Directory of Open Access Journals (Sweden)

    Li Mu

    2018-01-01

    Full Text Available In order to improve the reliability of power supply, a large number of electronic voltage and current transformers are used in digital substations. In this paper, the mathematical model of the electronic transformer is analyzed firstly, and its circuit model is given. According to the difference of working characteristics between voltage transformer and current transformer, the circuit model of voltage type electronic transformer and current type electronic transformer is given respectively. By analyzing their broadband transmission characteristics, the accuracy of the model is verified, and their lightning analysis models are obtained.

  16. Learning Action Models: Qualitative Approach

    NARCIS (Netherlands)

    Bolander, T.; Gierasimczuk, N.; van der Hoek, W.; Holliday, W.H.; Wang, W.-F.

    2015-01-01

    In dynamic epistemic logic, actions are described using action models. In this paper we introduce a framework for studying learnability of action models from observations. We present first results concerning propositional action models. First we check two basic learnability criteria: finite

  17. Cosmic-ray electrons in the closed-galaxy model

    International Nuclear Information System (INIS)

    Badhwar, G.D.; Stephens, S.A.

    1976-01-01

    We have examined the consequences of the ''closed galaxy'' cosmic-ray confinement model of Rasmussen and Peters with regard to the electron component of cosmic rays. It is found that the predictions of this model are inconsistent with the observed intensity and charge composition of electrons. The model is also inconsistent with the galactic radio emission

  18. modeling, observation and control, a multi-model approach

    OpenAIRE

    Elkhalil, Mansoura

    2011-01-01

    This thesis is devoted to the control of systems which dynamics can be suitably described by a multimodel approach from an investigation study of a model reference adaptative control performance enhancement. Four multimodel control approaches have been proposed. The first approach is based on an output reference model control design. A successful experimental validation involving a chemical reactor has been carried out. The second approach is based on a suitable partial state model reference ...

  19. A novel approach to electron data background treatment in an online wide-angle spectrometer for laser-accelerated ion and electron bunches

    Science.gov (United States)

    Lindner, F. H.; Bin, J. H.; Englbrecht, F.; Haffa, D.; Bolton, P. R.; Gao, Y.; Hartmann, J.; Hilz, P.; Kreuzer, C.; Ostermayr, T. M.; Rösch, T. F.; Speicher, M.; Parodi, K.; Thirolf, P. G.; Schreiber, J.

    2018-01-01

    Laser-based ion acceleration is driven by electrical fields emerging when target electrons absorb laser energy and consecutively leave the target material. A direct correlation between these electrons and the accelerated ions is thus to be expected and predicted by theoretical models. We report on a modified wide-angle spectrometer, allowing the simultaneous characterization of angularly resolved energy distributions of both ions and electrons. Equipped with online pixel detectors, the RadEye1 detectors, the investigation of this correlation gets attainable on a single shot basis. In addition to first insights, we present a novel approach for reliably extracting the primary electron energy distribution from the interfering secondary radiation background. This proves vitally important for quantitative extraction of average electron energies (temperatures) and emitted total charge.

  20. The electronic-commerce-oriented virtual merchandise model

    Science.gov (United States)

    Fang, Xiaocui; Lu, Dongming

    2004-03-01

    Electronic commerce has been the trend of commerce activities. Providing with Virtual Reality interface, electronic commerce has better expressing capacity and interaction means. But most of the applications of virtual reality technology in EC, 3D model is only the appearance description of merchandises. There is almost no information concerned with commerce information and interaction information. This resulted in disjunction of virtual model and commerce information. So we present Electronic Commerce oriented Virtual Merchandise Model (ECVMM), which combined a model with commerce information, interaction information and figure information of virtual merchandise. ECVMM with abundant information provides better support to information obtainment and communication in electronic commerce.

  1. Lessons on electronic decoherence in molecules from exact modeling

    Science.gov (United States)

    Hu, Wenxiang; Gu, Bing; Franco, Ignacio

    2018-04-01

    Electronic decoherence processes in molecules and materials are usually thought and modeled via schemes for the system-bath evolution in which the bath is treated either implicitly or approximately. Here we present computations of the electronic decoherence dynamics of a model many-body molecular system described by the Su-Schrieffer-Heeger Hamiltonian with Hubbard electron-electron interactions using an exact method in which both electronic and nuclear degrees of freedom are taken into account explicitly and fully quantum mechanically. To represent the electron-nuclear Hamiltonian in matrix form and propagate the dynamics, the computations employ the Jordan-Wigner transformation for the fermionic creation/annihilation operators and the discrete variable representation for the nuclear operators. The simulations offer a standard for electronic decoherence that can be used to test approximations. They also provide a useful platform to answer fundamental questions about electronic decoherence that cannot be addressed through approximate or implicit schemes. Specifically, through simulations, we isolate basic mechanisms for electronic coherence loss and demonstrate that electronic decoherence is possible even for one-dimensional nuclear bath. Furthermore, we show that (i) decreasing the mass of the bath generally leads to faster electronic decoherence; (ii) electron-electron interactions strongly affect the electronic decoherence when the electron-nuclear dynamics is not pure-dephasing; (iii) classical bath models with initial conditions sampled from the Wigner distribution accurately capture the short-time electronic decoherence dynamics; (iv) model separable initial superpositions often used to understand decoherence after photoexcitation are only relevant in experiments that employ delta-like laser pulses to initiate the dynamics. These insights can be employed to interpret and properly model coherence phenomena in molecules.

  2. Global energy modeling - A biophysical approach

    Energy Technology Data Exchange (ETDEWEB)

    Dale, Michael

    2010-09-15

    This paper contrasts the standard economic approach to energy modelling with energy models using a biophysical approach. Neither of these approaches includes changing energy-returns-on-investment (EROI) due to declining resource quality or the capital intensive nature of renewable energy sources. Both of these factors will become increasingly important in the future. An extension to the biophysical approach is outlined which encompasses a dynamic EROI function that explicitly incorporates technological learning. The model is used to explore several scenarios of long-term future energy supply especially concerning the global transition to renewable energy sources in the quest for a sustainable energy system.

  3. The electronic disability record: purpose, parameters, and model use case.

    Science.gov (United States)

    Tulu, Bengisu; Horan, Thomas A

    2009-01-01

    The active engagement of consumers is an important factor in achieving widespread success of health information systems. The disability community represents a major segment of the healthcare arena, with more than 50 million Americans experiencing some form of disability. In keeping with the "consumer-driven" approach to e-health systems, this paper considers the distinctive aspects of electronic and personal health record use by this segment of society. Drawing upon the information shared during two national policy forums on this topic, the authors present the concept of Electronic Disability Records (EDR). The authors outline the purpose and parameters of such records, with specific attention to its ability to organize health and financial data in a manner that can be used to expedite the disability determination process. In doing so, the authors discuss its interaction with Electronic Health Records (EHR) and Personal Health Records (PHR). The authors then draw upon these general parameters to outline a model use case for disability determination and discuss related implications for disability health management. The paper further reports on the subsequent considerations of these and related deliberations by the American Health Information Community (AHIC).

  4. Learning Actions Models: Qualitative Approach

    DEFF Research Database (Denmark)

    Bolander, Thomas; Gierasimczuk, Nina

    2015-01-01

    —they are identifiable in the limit.We then move on to a particular learning method, which proceeds via restriction of a space of events within a learning-specific action model. This way of learning closely resembles the well-known update method from dynamic epistemic logic. We introduce several different learning...... identifiability (conclusively inferring the appropriate action model in finite time) and identifiability in the limit (inconclusive convergence to the right action model). We show that deterministic actions are finitely identifiable, while non-deterministic actions require more learning power...... methods suited for finite identifiability of particular types of deterministic actions....

  5. Reconstructing Regional Ionospheric Electron Density: A Combined Spherical Slepian Function and Empirical Orthogonal Function Approach

    Science.gov (United States)

    Farzaneh, Saeed; Forootan, Ehsan

    2018-03-01

    The computerized ionospheric tomography is a method for imaging the Earth's ionosphere using a sounding technique and computing the slant total electron content (STEC) values from data of the global positioning system (GPS). The most common approach for ionospheric tomography is the voxel-based model, in which (1) the ionosphere is divided into voxels, (2) the STEC is then measured along (many) satellite signal paths, and finally (3) an inversion procedure is applied to reconstruct the electron density distribution of the ionosphere. In this study, a computationally efficient approach is introduced, which improves the inversion procedure of step 3. Our proposed method combines the empirical orthogonal function and the spherical Slepian base functions to describe the vertical and horizontal distribution of electron density, respectively. Thus, it can be applied on regional and global case studies. Numerical application is demonstrated using the ground-based GPS data over South America. Our results are validated against ionospheric tomography obtained from the constellation observing system for meteorology, ionosphere, and climate (COSMIC) observations and the global ionosphere map estimated by international centers, as well as by comparison with STEC derived from independent GPS stations. Using the proposed approach, we find that while using 30 GPS measurements in South America, one can achieve comparable accuracy with those from COSMIC data within the reported accuracy (1 × 1011 el/cm3) of the product. Comparisons with real observations of two GPS stations indicate an absolute difference is less than 2 TECU (where 1 total electron content unit, TECU, is 1016 electrons/m2).

  6. Representing electrons a biographical approach to theoretical entities

    CERN Document Server

    Arabatzis, Theodore

    2006-01-01

    Both a history and a metahistory, Representing Electrons focuses on the development of various theoretical representations of electrons from the late 1890s to 1925 and the methodological problems associated with writing about unobservable scientific entities. Using the electron-or rather its representation-as a historical actor, Theodore Arabatzis illustrates the emergence and gradual consolidation of its representation in physics, its career throughout old quantum theory, and its appropriation and reinterpretation by chemists. As Arabatzis develops this novel biographical

  7. Continuum multiple-scattering approach to electron-molecule scattering and molecular photoionization

    International Nuclear Information System (INIS)

    Dehmer, J.L.; Dill, D.

    1979-01-01

    The multiple-scattering approach to the electronic continuum of molecules is described. The continuum multiple-scattering model (CMSM) was developed as a survey tool and, as such was required to satisfy two requirements. First, it had to have a very broad scope, which means (i) molecules of arbitrary geometry and complexity containing any atom in the periodic system, (ii) continuum electron energies from 0-1000 eV, and (iii) capability to treat a large range of processes involving both photoionization and electron scattering. Second, the structure of the theory was required to lend itself to transparent, physical interpretation of major spectral features such as shape resonances. A comprehensive theoretical framework for the continuum multiple scattering method is presented, as well as its applications to electron-molecule scattering and molecular photoionization. Highlights of recent applications in these two areas are reviewed. The major impact of the resulting studies over the last few years has been to establish the importance of shape resonances in electron collisions and photoionization of practically all (non-hydride) molecules

  8. VHDL Model of Electronic-Lock System

    Directory of Open Access Journals (Sweden)

    J. Noga

    2000-04-01

    Full Text Available The paper describes the design of an electronic-lock system which wascompleted as part of the Basic VHDL course in the Department of Controland Measurement Faculty of Electrical Engineering and Informatics,Technical University of Ostrava, Czech Republic in co-operation withthe Department if Electronic Engineering, University of Hull, GreatBritain in the frame of TEMPUS project no. S_JEP/09468-95.

  9. A Unified Approach to Modeling and Programming

    DEFF Research Database (Denmark)

    Madsen, Ole Lehrmann; Møller-Pedersen, Birger

    2010-01-01

    of this paper is to go back to the future and get inspiration from SIMULA and propose a unied approach. In addition to reintroducing the contributions of SIMULA and the Scandinavian approach to object-oriented programming, we do this by discussing a number of issues in modeling and programming and argue3 why we......SIMULA was a language for modeling and programming and provided a unied approach to modeling and programming in contrast to methodologies based on structured analysis and design. The current development seems to be going in the direction of separation of modeling and programming. The goal...

  10. 3D invariant embedding model for backscattering electrons applied to materials characterization

    International Nuclear Information System (INIS)

    Figueroa, C.; Nieva, N.; Heluani, S.P.

    2007-01-01

    In this work, the results of a 3D model used to describe the fraction of backscattered electrons, together with its energy and angular distributions, are reported. This 3D model is the result of improvements in the Invariant Embedding Approach to Microanalysis (IEAM). Comparisons with experiment show that the theoretical results follow the general trend of experimental data, when parameters (such as atomic number, energy of the impinging electrons and tilted angle) are changed

  11. Modeling electron fractionalization with unconventional Fock spaces

    Science.gov (United States)

    Cobanera, Emilio

    2017-08-01

    It is shown that certain fractionally-charged quasiparticles can be modeled on D-dimensional lattices in terms of unconventional yet simple Fock algebras of creation and annihilation operators. These unconventional Fock algebras are derived from the usual fermionic algebra by taking roots (the square root, cubic root, etc) of the usual fermionic creation and annihilation operators. If the fermions carry non-Abelian charges, then this approach fractionalizes the Abelian charges only. In particular, the mth-root of a spinful fermion carries charge e/m and spin 1/2. Just like taking a root of a complex number, taking a root of a fermion yields a mildly non-unique result. As a consequence, there are several possible choices of quantum exchange statistics for fermion-root quasiparticles. These choices are tied to the dimensionality D=1,2,3,\\ldots of the lattice by basic physical considerations. One particular family of fermion-root quasiparticles is directly connected to the parafermion zero-energy modes expected to emerge in certain mesoscopic devices involving fractional quantum Hall states. Hence, as an application of potential mesoscopic interest, I investigate numerically the hybridization of Majorana and parafermion zero-energy edge modes caused by fractionalizing but charge-conserving tunneling.

  12. A Transport Model for Non-Local Heating of Electrons in ICP Reactors

    Science.gov (United States)

    Chang, C. H.; Bose, Deepak; Arnold, James O. (Technical Monitor)

    1998-01-01

    A new model has been developed for non-local heating of electrons in ICP reactors, based on a hydrodynamic approach. The model has been derived using the electron momentum conservation in azimuthal direction with electromagnetic and frictional forces respectively as driving force and damper of harmonic oscillatory motion of electrons. The resulting transport equations include the convection of azimuthal electron momentum in radial and axial directions, thereby accounting for the non-local effects. The azimuthal velocity of electrons and the resulting electrical current are coupled to the Maxwell's relations, thus forming a self-consistent model for non-local heating. This model is being implemented along with a set of Navier-Stokes equations for plasma dynamics and gas flow to simulate low-pressure (few mTorr's) ICP discharges. Characteristics of nitrogen plasma in a TCP 300mm etch reactor is being studied. The results will be compared against the available Langmuir probe measurements.

  13. Modeling a Miniaturized Scanning Electron Microscope Focusing Column - Lessons Learned in Electron Optics Simulation

    Science.gov (United States)

    Loyd, Jody; Gregory, Don; Gaskin, Jessica

    2016-01-01

    /Fourier series hybrid approach. The presentation will give background remarks about the MSFC mini Lunar SEM concept and electron optics modeling, followed by a description of the alternate field modeling techniques that were tried, along with their incorporation into a ray-trace simulation. Next, the validation of this simulation against commercially available software will be discussed using an example lens as a test case. Then, the efficacy of aberration assessment using direct ray-tracing will be demonstrated, using this same validation case. The discussion will include practical error checks of the field solution. Finally, the ray-trace assessment of the MSFC mini Lunar SEM concept will be shown and discussed. The authors believe this presentation will be of general interest to practitioners of modeling and simulation, as well as those with a general optics background. Because electron optics and photon optics share many basic concepts (e.g., lenses, images, aberrations, etc.), the appeal of this presentation need not be restricted to just those interested in charged particle optics.

  14. A Landau fluid model for dissipative trapped electron modes

    International Nuclear Information System (INIS)

    Hedrick, C.L.; Leboeuf, J.N.; Sidikman, K.L.

    1995-09-01

    A Landau fluid model for dissipative trapped electron modes is developed which focuses on an improved description of the ion dynamics. The model is simple enough to allow nonlinear calculations with many harmonics for the times necessary to reach saturation. The model is motivated by a discussion that starts with the gyro-kinetic equation and emphasizes the importance of simultaneously including particular features of magnetic drift resonance, shear, and Landau effects. To ensure that these features are simultaneously incorporated in a Landau fluid model with only two evolution equations, a new approach to determining the closure coefficients is employed. The effect of this technique is to reduce the matching of fluid and kinetic responses to a single variable, rather than two, and to allow focusing on essential features of the fluctuations in question, rather than features that are only important for other types of fluctuations. Radially resolved nonlinear calculations of this model, advanced in time to reach saturation, are presented to partially illustrate its intended use. These calculations have a large number of poloidal and toroidal harmonics to represent the nonlinear dynamics in a converged steady state which includes cascading of energy to both short and long wavelengths

  15. Szekeres models: a covariant approach

    Science.gov (United States)

    Apostolopoulos, Pantelis S.

    2017-05-01

    We exploit the 1  +  1  +  2 formalism to covariantly describe the inhomogeneous and anisotropic Szekeres models. It is shown that an average scale length can be defined covariantly which satisfies a 2d equation of motion driven from the effective gravitational mass (EGM) contained in the dust cloud. The contributions to the EGM are encoded to the energy density of the dust fluid and the free gravitational field E ab . We show that the quasi-symmetric property of the Szekeres models is justified through the existence of 3 independent intrinsic Killing vector fields (IKVFs). In addition the notions of the apparent and absolute apparent horizons are briefly discussed and we give an alternative gauge-invariant form to define them in terms of the kinematical variables of the spacelike congruences. We argue that the proposed program can be used in order to express Sachs’ optical equations in a covariant form and analyze the confrontation of a spatially inhomogeneous irrotational overdense fluid model with the observational data.

  16. Modeling mini-orange electron spectrometers

    International Nuclear Information System (INIS)

    Canzian da Silva, Nelson; Dietzsch, Olacio

    1994-01-01

    A method for calculating the transmission of mini-orange electron spectrometers is presented. The method makes use of the analytical solution for the magnetic field of a plane magnet in the calculation of the spectrometer spatial field distribution by superimposing the fields of the several magnets that compose the system. Electron trajectories through the spectrometer are integrated numerically in a Monte Carlo calculation and the transmission of the spectrometer as a function of the electron energy is evaluated. A six-magnet mini-orange spectrometer was built and its transmission functions for several distances from source to detector were measured and compared to the calculations. The overall agreement is found to be good. The method is quite general and can be applied to the design of systems composed of plane magnets, predicting their performance before assembling them. ((orig.))

  17. Vehicle height and posture control of the electronic air suspension system using the hybrid system approach

    Science.gov (United States)

    Sun, Xiaoqiang; Cai, Yingfeng; Chen, Long; Liu, Yanling; Wang, Shaohua

    2016-03-01

    The electronic air suspension (EAS) system can improve ride comfort, fuel economy and handling safety of vehicles by adjusting vehicle height. This paper describes the development of a novel controller using the hybrid system approach to adjust the vehicle height (height control) and to regulate the roll and pitch angles of the vehicle body during the height adjustment process (posture control). The vehicle height adjustment system of EAS poses challenging hybrid control problems, since it features different discrete modes of operation, where each mode has an associated linear continuous-time dynamic. In this paper, we propose a novel approach to the modelling and controller design problem for the vehicle height adjustment system of EAS. The system model is described firstly in the hybrid system description language (HYSDEL) to obtain a mixed logical dynamical (MLD) hybrid model. For the resulting model, a hybrid model predictive controller is tuned to improve the vehicle height and posture tracking accuracy and to achieve the on-off statuses direct control of solenoid valves. The effectiveness and performance of the proposed approach are demonstrated by simulations and actual vehicle tests.

  18. On quantum approach to modeling of plasmon photovoltaic effect

    DEFF Research Database (Denmark)

    Kluczyk, Katarzyna; David, Christin; Jacak, Witold Aleksander

    2017-01-01

    .g., upon commercial COMSOL software system). Both approaches are essentially classical ones and neglect quantum particularities related to plasmon excitations in metallic components. We demonstrate that these quantum plasmon effects are of crucial importance especially in theoretical simulations of plasmon...... to the semiconductor solar cell mediated by surface plasmons in metallic nanoparticles deposited on the top of the battery. In addition, short-ranged electron-electron interaction in metals is discussed in the framework of the semiclassical hydrodynamic model. The significance of the related quantum corrections...

  19. Multiple Model Approaches to Modelling and Control,

    DEFF Research Database (Denmark)

    appeal in building systems which operate robustly over a wide range of operating conditions by decomposing them into a number of simplerlinear modelling or control problems, even for nonlinear modelling or control problems. This appeal has been a factor in the development of increasinglypopular `local...... to problems in the process industries, biomedical applications and autonomoussystems. The successful application of the ideas to demanding problems is already encouraging, but creative development of the basic framework isneeded to better allow the integration of human knowledge with automated learning....... The underlying question is `How should we partition the system - what is `local'?'. This book presents alternative ways of bringing submodels together,which lead to varying levels of performance and insight. Some are further developed for autonomous learning of parameters from data, while others havefocused...

  20. Modeling software behavior a craftsman's approach

    CERN Document Server

    Jorgensen, Paul C

    2009-01-01

    A common problem with most texts on requirements specifications is that they emphasize structural models to the near exclusion of behavioral models-focusing on what the software is, rather than what it does. If they do cover behavioral models, the coverage is brief and usually focused on a single model. Modeling Software Behavior: A Craftsman's Approach provides detailed treatment of various models of software behavior that support early analysis, comprehension, and model-based testing. Based on the popular and continually evolving course on requirements specification models taught by the auth

  1. Modeling Electronic-Nuclear Interactions for Excitation Energy Transfer Processes in Light-Harvesting Complexes.

    Science.gov (United States)

    Lee, Mi Kyung; Coker, David F

    2016-08-18

    An accurate approach for computing intermolecular and intrachromophore contributions to spectral densities to describe the electronic-nuclear interactions relevant for modeling excitation energy transfer processes in light harvesting systems is presented. The approach is based on molecular dynamics (MD) calculations of classical correlation functions of long-range contributions to excitation energy fluctuations and a separate harmonic analysis and single-point gradient quantum calculations for electron-intrachromophore vibrational couplings. A simple model is also presented that enables detailed analysis of the shortcomings of standard MD-based excitation energy fluctuation correlation function approaches. The method introduced here avoids these problems, and its reliability is demonstrated in accurate predictions for bacteriochlorophyll molecules in the Fenna-Matthews-Olson pigment-protein complex, where excellent agreement with experimental spectral densities is found. This efficient approach can provide instantaneous spectral densities for treating the influence of fluctuations in environmental dissipation on fast electronic relaxation.

  2. System Behavior Models: A Survey of Approaches

    Science.gov (United States)

    2016-06-01

    the Petri model allowed a quick assessment of all potential states but was more cumbersome to build than the MP model. A comparison of approaches...identical state space results. The combined state space graph of the Petri model allowed a quick assessment of all potential states but was more...59 INITIAL DISTRIBUTION LIST ...................................................................................65 ix LIST

  3. Molecular modeling and multiscaling issues for electronic material applications

    CERN Document Server

    Iwamoto, Nancy; Yuen, Matthew; Fan, Haibo

    Volume 1 : Molecular Modeling and Multiscaling Issues for Electronic Material Applications provides a snapshot on the progression of molecular modeling in the electronics industry and how molecular modeling is currently being used to understand material performance to solve relevant issues in this field. This book is intended to introduce the reader to the evolving role of molecular modeling, especially seen through the eyes of the IEEE community involved in material modeling for electronic applications.  Part I presents  the role that quantum mechanics can play in performance prediction, such as properties dependent upon electronic structure, but also shows examples how molecular models may be used in performance diagnostics, especially when chemistry is part of the performance issue.  Part II gives examples of large-scale atomistic methods in material failure and shows several examples of transitioning between grain boundary simulations (on the atomistic level)and large-scale models including an example ...

  4. Many-body approach to electronic excitations concepts and applications

    CERN Document Server

    Bechstedt, Friedhelm

    2015-01-01

    The many-body-theoretical basis and applications of theoretical spectroscopy of condensed matter, e.g. crystals, nanosystems, and molecules are unified in one advanced text for readers from graduate students to active researchers in the field. The theory is developed from first principles including fully the electron-electron interaction and spin interactions. It is based on the many-body perturbation theory, a quantum-field-theoretical description, and Green's functions. The important expressions for ground states as well as electronic single-particle and pair excitations are explained. Based on single-particle and two-particle Green's functions, the Dyson and Bethe-Salpeter equations are derived. They are applied to calculate spectral and response functions. Important spectra are those which can be measured using photoemission/inverse photoemission, optical spectroscopy, and electron energy loss/inelastic X-ray spectroscopy. Important approximations are derived and discussed in the light of selected computa...

  5. Current approaches to gene regulatory network modelling

    Directory of Open Access Journals (Sweden)

    Brazma Alvis

    2007-09-01

    Full Text Available Abstract Many different approaches have been developed to model and simulate gene regulatory networks. We proposed the following categories for gene regulatory network models: network parts lists, network topology models, network control logic models, and dynamic models. Here we will describe some examples for each of these categories. We will study the topology of gene regulatory networks in yeast in more detail, comparing a direct network derived from transcription factor binding data and an indirect network derived from genome-wide expression data in mutants. Regarding the network dynamics we briefly describe discrete and continuous approaches to network modelling, then describe a hybrid model called Finite State Linear Model and demonstrate that some simple network dynamics can be simulated in this model.

  6. Orbital Models and Electronic Structure Theory

    DEFF Research Database (Denmark)

    Linderberg, Jan

    2012-01-01

    This tribute to the work by Carl Johan Ballhausen focuses on the emergence of quantitative means for the study of the electronic properties of complexes and molecules. Development, refinement and application of the orbital picture elucidated electric and magnetic features of ranges of molecules w...

  7. An exciton approach to the excited states of two electron atoms. I Formalism and interpretation

    International Nuclear Information System (INIS)

    Schipper, P.E.

    1985-01-01

    The exciton model is formally applied to a description of the excited states of two electron atoms with the explicit inclusion of exchange. The model leads to a conceptually simple framework for the discussion of the electronic properties of the archetypical atomic electron pair

  8. Distributed simulation a model driven engineering approach

    CERN Document Server

    Topçu, Okan; Oğuztüzün, Halit; Yilmaz, Levent

    2016-01-01

    Backed by substantive case studies, the novel approach to software engineering for distributed simulation outlined in this text demonstrates the potent synergies between model-driven techniques, simulation, intelligent agents, and computer systems development.

  9. Validation of Modeling Flow Approaching Navigation Locks

    Science.gov (United States)

    2013-08-01

    USACE, Pittsburgh District ( LRP ) requested that the US Army Engineer Research and Development Center, Coastal and ERDC/CHL TR-13-9 2 Hydraulics...approaching the lock and dam. The second set of experiments considered a design, referred to as Plan B lock approach, which contained the weir field in...conditions and model parameters A discharge of 1.35 cfs was set as the inflow boundary condition at the upstream end of the model. The outflow boundary was

  10. Electronic Warfare in Army Models - A Survey.

    Science.gov (United States)

    1980-08-01

    CCM) PROVING GROUND TENIAS SAMJAM EIEM SPREAD SPECTRUM US ARMY ELECTRONIC FOREIGN SCIENCE & OFFICE OF MISSILE WARFARE LAB (EWL) TECHNOLOGY CENTER...IPAR MULTIRADAR SPREAD SPECTRUM ECMFUZ IRSS OTOALOC TAC ZINGERS EIEM ITF PATCOM TAM EOCM SIM FAC MGM-H4D RFSS TENIAS GTSF MG(-H4H ROLJAM ZAP I HMSM MSL...USAFAS TRASANA USAPAS TCF ASD WPAFU TENIAS ______ ___ ECAC _________ WAR EAGLE _________CATRADA WARRANT am________ 3DBDM ZAP 1 ____________ MEW EWL ZAP 2

  11. Reliability Modeling of Critical Electronic Devices.

    Science.gov (United States)

    1983-05-01

    Electronics, Vol. QE-15, No. 1, up January 1979, pp. 11-13. 15. Newman, D.H. and Ritchie, S., Degradation Pnenomena in Gallium Aluminium Arsenide Stripe...8217RESERVOIR COLD CATHODE TRAP FIGURE 7.2-1: HELIUM-CADMIUM LASER TUBE Principle design considerations relating to the lifetime of the device include (Ref 1): o...available in two basic design types. The contact design is either screw machined or stamped and formed. The screw machined contacts are close entry

  12. Mathematical model I. Electron and quantum mechanics

    OpenAIRE

    Nitin Ramchandra Gadre

    2011-01-01

    The basic particle electron obeys various theories like electrodynamics, quantum mechanics and special relativity. Particle under different experimental conditions behaves differently, allowing us to observe different characteristics which become basis for these theories. In this paper, we have made an attempt to suggest a classical picture by studying the requirements of these three modern theories. The basic presumption is: There must be certain structural characteristics in a particle like...

  13. Electronic learning and constructivism: a model for nursing education.

    Science.gov (United States)

    Kala, Sasikarn; Isaramalai, Sang-Arun; Pohthong, Amnart

    2010-01-01

    Nurse educators are challenged to teach nursing students to become competent professionals, who have both in-depth knowledge and decision-making skills. The use of electronic learning methods has been found to facilitate the teaching-learning process in nursing education. Although learning theories are acknowledged as useful guides to design strategies and activities of learning, integration of these theories into technology-based courses appears limited. Constructivism is a theoretical paradigm that could prove to be effective in guiding the design of electronic learning experiences for the purpose of providing positive outcomes, such as the acquisition of knowledge and decision-making skills. Therefore, the purposes of this paper are to: describe electronic learning, present a brief overview of what is known about the outcomes of electronic learning, discuss constructivism theory, present a model for electronic learning using constructivism, and describe educators' roles emphasizing the utilization of the model in developing electronic learning experiences in nursing education.

  14. Power Electronic Packaging Design, Assembly Process, Reliability and Modeling

    CERN Document Server

    Liu, Yong

    2012-01-01

    Power Electronic Packaging presents an in-depth overview of power electronic packaging design, assembly,reliability and modeling. Since there is a drastic difference between IC fabrication and power electronic packaging, the book systematically introduces typical power electronic packaging design, assembly, reliability and failure analysis and material selection so readers can clearly understand each task's unique characteristics. Power electronic packaging is one of the fastest growing segments in the power electronic industry, due to the rapid growth of power integrated circuit (IC) fabrication, especially for applications like portable, consumer, home, computing and automotive electronics. This book also covers how advances in both semiconductor content and power advanced package design have helped cause advances in power device capability in recent years. The author extrapolates the most recent trends in the book's areas of focus to highlight where further improvement in materials and techniques can d...

  15. Finite Element Models for Electron Beam Freeform Fabrication Process

    Science.gov (United States)

    Chandra, Umesh

    2012-01-01

    Electron beam freeform fabrication (EBF3) is a member of an emerging class of direct manufacturing processes known as solid freeform fabrication (SFF); another member of the class is the laser deposition process. Successful application of the EBF3 process requires precise control of a number of process parameters such as the EB power, speed, and metal feed rate in order to ensure thermal management; good fusion between the substrate and the first layer and between successive layers; minimize part distortion and residual stresses; and control the microstructure of the finished product. This is the only effort thus far that has addressed computer simulation of the EBF3 process. The models developed in this effort can assist in reducing the number of trials in the laboratory or on the shop floor while making high-quality parts. With some modifications, their use can be further extended to the simulation of laser, TIG (tungsten inert gas), and other deposition processes. A solid mechanics-based finite element code, ABAQUS, was chosen as the primary engine in developing these models whereas a computational fluid dynamics (CFD) code, Fluent, was used in a support role. Several innovative concepts were developed, some of which are highlighted below. These concepts were implemented in a number of new computer models either in the form of stand-alone programs or as user subroutines for ABAQUS and Fluent codes. A database of thermo-physical, mechanical, fluid, and metallurgical properties of stainless steel 304 was developed. Computing models for Gaussian and raster modes of the electron beam heat input were developed. Also, new schemes were devised to account for the heat sink effect during the deposition process. These innovations, and others, lead to improved models for thermal management and prediction of transient/residual stresses and distortions. Two approaches for the prediction of microstructure were pursued. The first was an empirical approach involving the

  16. A laser printing based approach for printed electronics

    Science.gov (United States)

    Zhang, T.; Hu, M.; Liu, Y.; Guo, Q.; Wang, X.; Zhang, W.; Lau, W.; Yang, J.

    2016-03-01

    Here we report a study of printing of electronics using an office use laser printer. The proposed method eliminates those critical disadvantages of solvent-based printing techniques by taking the advantages of electroless deposition and laser printing. The synthesized toner acts as a catalyst for the electroless copper deposition as well as an adhesion-promoting buffer layer between the substrate and deposited copper. The easy metallization of printed patterns and strong metal-substrate adhesion make it an especially effective method for massive production of flexible printed circuits. The proposed process is a high throughput, low cost, efficient, and environmentally benign method for flexible electronics manufacturing.

  17. Hybrid approaches to physiologic modeling and prediction

    Science.gov (United States)

    Olengü, Nicholas O.; Reifman, Jaques

    2005-05-01

    This paper explores how the accuracy of a first-principles physiological model can be enhanced by integrating data-driven, "black-box" models with the original model to form a "hybrid" model system. Both linear (autoregressive) and nonlinear (neural network) data-driven techniques are separately combined with a first-principles model to predict human body core temperature. Rectal core temperature data from nine volunteers, subject to four 30/10-minute cycles of moderate exercise/rest regimen in both CONTROL and HUMID environmental conditions, are used to develop and test the approach. The results show significant improvements in prediction accuracy, with average improvements of up to 30% for prediction horizons of 20 minutes. The models developed from one subject's data are also used in the prediction of another subject's core temperature. Initial results for this approach for a 20-minute horizon show no significant improvement over the first-principles model by itself.

  18. Electronic Business Development as a Sustainable Competitive Advantage Model

    Directory of Open Access Journals (Sweden)

    Narimantas Kazimieras Paliulis

    2012-07-01

    Full Text Available The paper examines the practical usefulness of information technologies in business reviewing electronic business concepts provided in science literature and also the newest tendencies of electronic business development. The paper offers a review of various authors works on e-strategies and IT influence on companies’ functionality. An analysis of disadvantages in various electronic business development models is provided. On the basis of analyses done on the theory of electronic business development and on disadvantages of e-business models, the main aspects of e-business development as sustainable competitive advantage are identified. A fully – formed model of electronic business development as sustainable competitive advantage is presented. Conclusions are provided.Article in Lithuanian

  19. Integrating Electronic Resources into the Library Catalog: A Collaborative Approach.

    Science.gov (United States)

    Herrera, Gail; Aldana, Lynda

    2001-01-01

    Describes a project at the University of Mississippi Libraries to catalog purchased electronic resources so that access to these resources is available only via the Web-based library catalog. Discusses collaboration between cataloging and systems personnel; and describes the MARC catalog record field that contains the information needed to locate…

  20. The highly reintegrative approach of electronic monitoring in the Netherlands

    NARCIS (Netherlands)

    Boone, M.M.; Kooij, van der M.; Rap, S.E.

    2017-01-01

    This contribution describes the way electronic monitoring (EM) is organized and implemented in the Netherlands. It will become clear that the situation in the Netherlands is characterized by, in particular, two features. The application of EM is highly interwoven with the Probation Service and its

  1. Inverse Problem Approach for the Alignment of Electron Tomographic Series.

    OpenAIRE

    Tran , Viet Dung; Moreaud , Maxime; Thiébaut , Éric; Denis , L.; Becker , Jean-Marie

    2014-01-01

    In the refining industry, morphological measurements of particles have become an essential part in the characterization catalyst supports. Through these parameters, one can infer the specific physicochemical properties of the studied materials. One of the main acquisition techniques is electron tomography (or nanotomography). 3D volumes are reconstructed from sets of projections from different angles made by a Transmission Elect...

  2. The electron-propagator approach to conceptual density-functional ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Both electron propagator theory and density-functional theory provide conceptually useful information about chemical reactivity and, most especially, charge transfer. This paper elucidates the qualitative and quantitative links between the two theories, with emphasis on how the reactivity indica- tors of conceptual ...

  3. The electron-propagator approach to conceptual density-functional ...

    Indian Academy of Sciences (India)

    Both electron propagator theory and density-functional theory provide conceptually useful information about chemical reactivity and, most especially, charge transfer. This paper elucidates thequalitative and quantitative links between the two theories, with emphasis on how the reactivity indicators of conceptual ...

  4. Modeling Electronic Skin Response to Normal Distributed Force

    Directory of Open Access Journals (Sweden)

    Lucia Seminara

    2018-02-01

    Full Text Available The reference electronic skin is a sensor array based on PVDF (Polyvinylidene fluoride piezoelectric polymers, coupled to a rigid substrate and covered by an elastomer layer. It is first evaluated how a distributed normal force (Hertzian distribution is transmitted to an extended PVDF sensor through the elastomer layer. A simplified approach based on Boussinesq’s half-space assumption is used to get a qualitative picture and extensive FEM simulations allow determination of the quantitative response for the actual finite elastomer layer. The ultimate use of the present model is to estimate the electrical sensor output from a measure of a basic mechanical action at the skin surface. However this requires that the PVDF piezoelectric coefficient be known a-priori. This was not the case in the present investigation. However, the numerical model has been used to fit experimental data from a real skin prototype and to estimate the sensor piezoelectric coefficient. It turned out that this value depends on the preload and decreases as a result of PVDF aging and fatigue. This framework contains all the fundamental ingredients of a fully predictive model, suggesting a number of future developments potentially useful for skin design and validation of the fabrication technology.

  5. Electron and photon reconstruction and performance in ATLAS using a dynamical, topological cell clustering-based approach

    CERN Document Server

    The ATLAS collaboration

    2017-01-01

    The electron and photon reconstruction in ATLAS has moved towards the use of a dynamical, topo- logical cell-based approach for cluster building, owing to advancements in the calibration procedure which allow for such a method to be applied. The move to this new technique allows for improved measurements of electron and photon energies, particularly in situations where an electron radiates a bremsstrahlung photon, or a photon converts to an electron-poistron pair. This note details the changes to the ATLAS electron and photon reconstruction software, and assesses its performance under current LHC luminosity conditions using simulated data. Changes to the converted photon reconstruction are also detailed, which improve the reconstruction efficiency of double-track converted photons, as well as reducing the reconstruction of spurious one-track converted photons. The performance of the new reconstruction algorithm is also presented in a number of important topologies relevant to precision Standard Model physics,...

  6. New two-fluid (localized + band electron) model for manganites

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. New two-fluid (localized + band electron) model for manganites. ( With HR Krishnamurthy,GV Pai,SR Hassan,V Shenoy,. Key ideas: T Gupta ….) Two types of eg electronic states arise in doped manganites (due to strong JT coupling, strong U, filling conditions, …):.

  7. Problem Resolution through Electronic Mail: A Five-Step Model.

    Science.gov (United States)

    Grandgenett, Neal; Grandgenett, Don

    2001-01-01

    Discusses the use of electronic mail within the general resolution and management of administrative problems and emphasizes the need for careful attention to problem definition and clarity of language. Presents a research-based five-step model for the effective use of electronic mail based on experiences at the University of Nebraska at Omaha.…

  8. Risk Modelling for Passages in Approach Channel

    Directory of Open Access Journals (Sweden)

    Leszek Smolarek

    2013-01-01

    Full Text Available Methods of multivariate statistics, stochastic processes, and simulation methods are used to identify and assess the risk measures. This paper presents the use of generalized linear models and Markov models to study risks to ships along the approach channel. These models combined with simulation testing are used to determine the time required for continuous monitoring of endangered objects or period at which the level of risk should be verified.

  9. Electronic Modeling and Design for Extreme Temperatures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We are developing CAD tools, models and methodologies for electronics design for circuit operation in extreme environments with focus on very low temperatures...

  10. Electronic field emission models beyond the Fowler-Nordheim one

    Science.gov (United States)

    Lepetit, Bruno

    2017-12-01

    We propose several quantum mechanical models to describe electronic field emission from first principles. These models allow us to correlate quantitatively the electronic emission current with the electrode surface details at the atomic scale. They all rely on electronic potential energy surfaces obtained from three dimensional density functional theory calculations. They differ by the various quantum mechanical methods (exact or perturbative, time dependent or time independent), which are used to describe tunneling through the electronic potential energy barrier. Comparison of these models between them and with the standard Fowler-Nordheim one in the context of one dimensional tunneling allows us to assess the impact on the accuracy of the computed current of the approximations made in each model. Among these methods, the time dependent perturbative one provides a well-balanced trade-off between accuracy and computational cost.

  11. Cosolvent approach for solution-processable electronic thin films.

    Science.gov (United States)

    Lin, Zhaoyang; He, Qiyuan; Yin, Anxiang; Xu, Yuxi; Wang, Chen; Ding, Mengning; Cheng, Hung-Chieh; Papandrea, Benjamin; Huang, Yu; Duan, Xiangfeng

    2015-04-28

    Low-temperature solution-processable electronic materials are of considerable interest for large-area, low-cost electronics, thermoelectrics, and photovoltaics. Using a soluble precursor and suitable solvent to formulate a semiconductor ink is essential for large-area fabrication of semiconductor thin films. To date, it has been shown that hydrazine can be used as a versatile solvent to process a wide range of inorganic semiconductors. However, hydrazine is highly toxic and not suitable for large-scale manufacturing. Here we report a binary mixed solvent of amine and thiol for effective dispersion and dissolution of a large number of inorganic semiconductors including Cu2S, Cu2Se, In2S3, In2Se3, CdS, SnSe, and others. The mixed solvent is significantly less toxic and safer than hydrazine, while at the same time offering the comparable capability of formulating diverse semiconductor ink with a concentration as high as >200 mg/mL. We further show that such ink material can be readily processed into high-performance semiconducting thin films (Cu2S and Cu2Se) with the highest room-temperature conductivity among solution-based materials. Furthermore, we show that complex semiconductor alloys with tunable band gaps, such as CuIn(S(x)Se(1-x))2 (0 ≤ x ≤ 1), can also be readily prepared by simply mixing Cu2S, Cu2Se, In2S3, and In2Se3 ink solutions in a proper ratio. Our study outlines a general strategy for the formulation of inorganic semiconductor ink for low-temperature processing of large-area electronic thin films on diverse substrates and can greatly impact diverse areas including flexible electronics, thermoelectrics, and photovoltaics.

  12. Modelling and implementing electronic health records in Denmark

    DEFF Research Database (Denmark)

    Bernstein, Knut; Rasmussen, Morten Bruun; Vingtoft, Søren

    2003-01-01

    The Danish Health IT strategy points out that integration between electronic health records (EHR) systems has a high priority. This paper reporst reports new tendencies in modelling and integration platforms globally and how this is reflected in the natinal development.......The Danish Health IT strategy points out that integration between electronic health records (EHR) systems has a high priority. This paper reporst reports new tendencies in modelling and integration platforms globally and how this is reflected in the natinal development....

  13. Confidence Level Based Approach to Total Dose Specification for Spacecraft Electronics

    Science.gov (United States)

    Xapsos, M. A.; Stauffer, C.; Phan, A.; McClure, S. S.; Ladbury, R. L.; Pellish, J. A.; Campola, M. J.; Label, K. A.

    2017-01-01

    A confidence level based approach to total dose radiation hardness assurance is presented for spacecraft electronics. It is applicable to both ionizing and displacement damage dose. Results are compared to the traditional approach that uses radiation design margin and advantages of the new approach are discussed.

  14. Real-space grids and the Octopus code as tools for the development of new simulation approaches for electronic systems

    Science.gov (United States)

    Andrade, Xavier; Strubbe, David; De Giovannini, Umberto; Larsen, Ask Hjorth; Oliveira, Micael J. T.; Alberdi-Rodriguez, Joseba; Varas, Alejandro; Theophilou, Iris; Helbig, Nicole; Verstraete, Matthieu J.; Stella, Lorenzo; Nogueira, Fernando; Aspuru-Guzik, Alán; Castro, Alberto; Marques, Miguel A. L.; Rubio, Angel

    Real-space grids are a powerful alternative for the simulation of electronic systems. One of the main advantages of the approach is the flexibility and simplicity of working directly in real space where the different fields are discretized on a grid, combined with competitive numerical performance and great potential for parallelization. These properties constitute a great advantage at the time of implementing and testing new physical models. Based on our experience with the Octopus code, in this article we discuss how the real-space approach has allowed for the recent development of new ideas for the simulation of electronic systems. Among these applications are approaches to calculate response properties, modeling of photoemission, optimal control of quantum systems, simulation of plasmonic systems, and the exact solution of the Schr\\"odinger equation for low-dimensionality systems.

  15. Towards new approaches in phenological modelling

    Science.gov (United States)

    Chmielewski, Frank-M.; Götz, Klaus-P.; Rawel, Harshard M.; Homann, Thomas

    2014-05-01

    Modelling of phenological stages is based on temperature sums for many decades, describing both the chilling and the forcing requirement of woody plants until the beginning of leafing or flowering. Parts of this approach go back to Reaumur (1735), who originally proposed the concept of growing degree-days. Now, there is a growing body of opinion that asks for new methods in phenological modelling and more in-depth studies on dormancy release of woody plants. This requirement is easily understandable if we consider the wide application of phenological models, which can even affect the results of climate models. To this day, in phenological models still a number of parameters need to be optimised on observations, although some basic physiological knowledge of the chilling and forcing requirement of plants is already considered in these approaches (semi-mechanistic models). Limiting, for a fundamental improvement of these models, is the lack of knowledge about the course of dormancy in woody plants, which cannot be directly observed and which is also insufficiently described in the literature. Modern metabolomic methods provide a solution for this problem and allow both, the validation of currently used phenological models as well as the development of mechanistic approaches. In order to develop this kind of models, changes of metabolites (concentration, temporal course) must be set in relation to the variability of environmental (steering) parameters (weather, day length, etc.). This necessarily requires multi-year (3-5 yr.) and high-resolution (weekly probes between autumn and spring) data. The feasibility of this approach has already been tested in a 3-year pilot-study on sweet cherries. Our suggested methodology is not only limited to the flowering of fruit trees, it can be also applied to tree species of the natural vegetation, where even greater deficits in phenological modelling exist.

  16. Pseudoclassical approach to electron and ion density correlations in simple liquid metals

    International Nuclear Information System (INIS)

    Vericat, F.; Tosi, M.P.; Pastore, G.

    1986-04-01

    Electron-electron and electron-ion structural correlations in simple liquid metals are treated by using effective pair potentials to incorporate quantal effects into a pseudoclassical description of the electron fluid. An effective pair potential between simultaneous electron density fluctuations is first constructed from known properties of the degenerate jellium model, which are the plasmon sum rule, the Kimball-Niklasson relation and Yasuhara's values of the electron pair distribution function at contact. An analytic expression is thereby obtained in the Debye-Hueckel approximation for the electronic structure factor in jellium over a range of density appropriate to metals, with results which compare favourably with those of fully quantal evaluations. A simple pseudoclassical model is then set up for a liquid metal: this involves a model of charged hard spheres for the ion-ion potential and an empty core model for the electron-ion potential, the Coulombic tails being scaled as required by the relation between the long-wavelength partial structure factors and the isothermal compressibility of the metal. The model is solved analytically by a pseudoclassical linear response treatment of the electron-ion coupling and numerical results are reported for partial structure factors in liquid sodium and liquid beryllium. Contact is made for the latter system with data on the electron-electron structure factor in the crystal from inelastic X-ray scattering experiments of Eisenberger, Marra and Brown. (author)

  17. Accounting of inter-electron correlations in the model of mobile electron shells

    International Nuclear Information System (INIS)

    Panov, Yu.D.; Moskvin, A.S.

    2000-01-01

    One studied the basic peculiar features of the model for mobile electron shells for multielectron atom or cluster. One offered a variation technique to take account of the electron correlations where the coordinates of the centre of single-particle atomic orbital served as variation parameters. It enables to interpret dramatically variation of electron density distribution under anisotropic external effect in terms of the limited initial basis. One studied specific correlated states that might make correlation contribution into the orbital current. Paper presents generalization of the typical MO-LCAO pattern with the limited set of single particle functions enabling to take account of additional multipole-multipole interactions in the cluster [ru

  18. Developing a model for application of electronic banking based on electronic trust

    Directory of Open Access Journals (Sweden)

    Amir Hooshang Nazarpoori

    2014-05-01

    Full Text Available This study develops a model for application of electronic banking based on electronic trust among costumers of Day bank in KhoramAbad city. A sample of 150 people was selected based on stratified random sampling. Questionnaires were used for the investigation. Results indicate that technology-based factors, user-based factors, and trust had negative relationships with perceived risk types including financial, functional, personal, and private. Moreover, trust including trust in system and trust in bank had a positive relationship with tendency to use and real application of electronic banking.

  19. A model for electron/ion recombination in ionization chambers

    International Nuclear Information System (INIS)

    Sailor, W.C.

    1988-05-01

    The recombination of free electrons and positive ions along charged particle tracks in gases has been modeled using electron tranport equations, which assume homogeneous distribution in the vicinity of the tracks. The equations include space charge terms, which have been negelected in previous models. A formula for the electron yield as a function of detector applied potential is obtained from a perturbation solution valid when the ratio of the Debye length to the charge column radius is larger then unity. When this ratio is very large, the formula reduces to that of previous models. Pulse height measurements in a 3 He ionization chamber indicate 2% to 30% losses to recombination which vary with applied field, particle type, and energy. Using reasonable values for the electron transport coefficients, the calculated loss of signal to recommendation is generally in agreement with experiment, but the variation with applied bias is stronger in the experiment

  20. Combined electronic structure and evolutionary search approach to materials design

    DEFF Research Database (Denmark)

    Johannesson, Gisli Holmar; Bligaard, Thomas; Ruban, Andrei

    2002-01-01

    We show that density functional theory calculations have reached an accuracy and speed making it possible to use them in conjunction with an evolutionary algorithm to search for materials with specific properties. The approach is illustrated by finding the most stable four component alloys out...

  1. Electronic system level design an open-source approach

    CERN Document Server

    Rigo, Sandro; Santos, Luiz

    2014-01-01

    This book devises ESL design from the pragmatic perspective of a SystemC-based representation by showing how to build and how to use ESL languages, models and tools. It includes TLM 2.0 and step-by-step examples; it also addresses power modeling.

  2. SLS Navigation Model-Based Design Approach

    Science.gov (United States)

    Oliver, T. Emerson; Anzalone, Evan; Geohagan, Kevin; Bernard, Bill; Park, Thomas

    2018-01-01

    The SLS Program chose to implement a Model-based Design and Model-based Requirements approach for managing component design information and system requirements. This approach differs from previous large-scale design efforts at Marshall Space Flight Center where design documentation alone conveyed information required for vehicle design and analysis and where extensive requirements sets were used to scope and constrain the design. The SLS Navigation Team has been responsible for the Program-controlled Design Math Models (DMMs) which describe and represent the performance of the Inertial Navigation System (INS) and the Rate Gyro Assemblies (RGAs) used by Guidance, Navigation, and Controls (GN&C). The SLS Navigation Team is also responsible for the navigation algorithms. The navigation algorithms are delivered for implementation on the flight hardware as a DMM. For the SLS Block 1-B design, the additional GPS Receiver hardware is managed as a DMM at the vehicle design level. This paper provides a discussion of the processes and methods used to engineer, design, and coordinate engineering trades and performance assessments using SLS practices as applied to the GN&C system, with a particular focus on the Navigation components. These include composing system requirements, requirements verification, model development, model verification and validation, and modeling and analysis approaches. The Model-based Design and Requirements approach does not reduce the effort associated with the design process versus previous processes used at Marshall Space Flight Center. Instead, the approach takes advantage of overlap between the requirements development and management process, and the design and analysis process by efficiently combining the control (i.e. the requirement) and the design mechanisms. The design mechanism is the representation of the component behavior and performance in design and analysis tools. The focus in the early design process shifts from the development and

  3. Task Flow Modeling in Electronic Business Environments

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available In recent years, internet based commerce has developed as a new paradigm. Many factors such as "at home delivery", easy ordering, and usually lower prices contributed to the success of the e-commerce. However, more recently, companies realized that one of the major factors in having a successful internet based business is the design of a user interface that is in concordance with the users' expectations, which includes both functionality and user friendly features. The func-tionality feature of an e-business interface is one of the most important elements when discussing about a specific internet based business. In our paper, we present methods to model task flows for e-business interfaces. We strengthen our study with the design modeling of a practical scenario that may appear in an on-line commercial environment.

  4. Novel approaches to study low-energy electron-induced damage to DNA oligonucleotides

    International Nuclear Information System (INIS)

    Rackwitz, Jenny; Bald, Ilko; Ranković, Miloš Lj; Milosavljević, Aleksandar R

    2015-01-01

    The novel approach of DNA origami structures as templates for precise quantification of various well- defined oligonucleotides provides the opportunity to determine the sensitivity of complex DNA sequences towards low-energy electrons. (paper)

  5. Renormalization group-theoretic approach to electron localization in disordered systems

    International Nuclear Information System (INIS)

    Kumar, N.; Heinrichs, J.

    1977-06-01

    The localization problem for the Anderson tight-binding model with site-diagonal (gaussian) disorder is studied, using a previously established analogy between this problem and the statistical mechanics of a zero-component classical field. The equivalent free-energy functional turns out to have complex coefficients in the bilinear terms but involves a real repulsive quartic interaction. The averaged one-electron propagator corresponds to the two-point correlation function for the equivalent statistical problem and the critical point gives the mobility edge, which is identified with the (real) fixed point energy of the associated renormalization group. Since for convergence reasons the conventional perturbative treatment of Wilson's formula is invalid, it is resorted to a non-perturbative approach which leads to a physical fixed point corresponding to a repulsive quartic interaction. The results for the mobility edge in three dimensions and for the critical disorder for an Anderson transition in two dimensions agree well with previous detailed predictions. The critical indices describing the approach of the transition at the mobility edge of various physical quantities, within the epsilon-expansion are also discussed. The more general problem where both diagonal and off-diagonal disorder is present in the Anderson hamiltonian is considered. In this case it is shown that the Hamilton function for the equivalent zero-component classical field model involves an additional biquadratic exchange term. From a simple generalization of Wilson's recursion relation and its non-perturbative solution explicit expressions for the mobility edges for weak diagonal and off-diagonal disorder in two and three dimensions are obtained. Our treatment casts doubts on the validity of recent conclusions about electron localization based on the renormalization group study of the nm-component spin model

  6. Method for secure electronic voting system: face recognition based approach

    Science.gov (United States)

    Alim, M. Affan; Baig, Misbah M.; Mehboob, Shahzain; Naseem, Imran

    2017-06-01

    In this paper, we propose a framework for low cost secure electronic voting system based on face recognition. Essentially Local Binary Pattern (LBP) is used for face feature characterization in texture format followed by chi-square distribution is used for image classification. Two parallel systems are developed based on smart phone and web applications for face learning and verification modules. The proposed system has two tire security levels by using person ID followed by face verification. Essentially class specific threshold is associated for controlling the security level of face verification. Our system is evaluated three standard databases and one real home based database and achieve the satisfactory recognition accuracies. Consequently our propose system provides secure, hassle free voting system and less intrusive compare with other biometrics.

  7. A first approach to runaway electron control in FTU

    Energy Technology Data Exchange (ETDEWEB)

    Boncagni, L. [Associazione Euratom/ENEA sulla Fusione, Centro Ricerche Frascati, CP 65, 00044 Frascati, Roma (Italy); Carnevale, D., E-mail: carnevaledaniele@gmail.com [Dipartimento Ing. Civile ed Ing. Informatica Università di Roma, Tor Vergata, Via del Politecnico 1, 00133 Roma (Italy); Cianfarani, C.; Esposito, B. [Associazione Euratom/ENEA sulla Fusione, Centro Ricerche Frascati, CP 65, 00044 Frascati, Roma (Italy); Granucci, G. [Associazione Euratom-CNR sulla Fusione, IFP-CNR, Via R. Cozzi 53, 20125 Milano (Italy); Maddaluno, G.; Marocco, D. [Associazione Euratom/ENEA sulla Fusione, Centro Ricerche Frascati, CP 65, 00044 Frascati, Roma (Italy); Martin-Solis, J.R. [Universidad Carlos III de Madrid, Avda. de la Universidad 30, 28911 Leganes-Madrid (Spain); Pucella, G. [Associazione Euratom/ENEA sulla Fusione, Centro Ricerche Frascati, CP 65, 00044 Frascati, Roma (Italy); Sozzi, C. [Associazione Euratom-CNR sulla Fusione, IFP-CNR, Via R. Cozzi 53, 20125 Milano (Italy); Varano, G. [Dipartimento Ing. Civile ed Ing. Informatica Università di Roma, Tor Vergata, Via del Politecnico 1, 00133 Roma (Italy); Vitale, V. [Associazione Euratom/ENEA sulla Fusione, Centro Ricerche Frascati, CP 65, 00044 Frascati, Roma (Italy); Zaccarian, L. [CNRS, LAAS, 7 av. du colonel Roche, F-31400 Toulouse (France); Univ. de Toulouse, LAAS, F-31400 Toulouse (France)

    2013-10-15

    The Plasma Control System (PCS) of the Frascati Tokamak Upgrade (FTU) is not equipped with any runaway electron (RE) beam control or suppression tool. In this paper we propose an upgraded PCS including an architecture for the control of disruption-generated REs that, making use of filtering techniques to estimate the onsets of the current quench (CQ) and of the RE beam current plateau, provides a controlled plasma current shut-down and a simultaneous RE position control. The control strategy is based on a nonlinear technique, called Input Allocation, that allows to re-configure the current in the poloidal field (PF) coils and improve the PCS responsiveness needed for RE position control. Preliminary results on the implementation of the Input Allocation and an experimental proposal to test the control scheme architecture are discussed.

  8. Classical Antiferromagnetism in Kinetically Frustrated Electronic Models

    Science.gov (United States)

    Sposetti, C. N.; Bravo, B.; Trumper, A. E.; Gazza, C. J.; Manuel, L. O.

    2014-05-01

    We study, by means of the density matrix renormalization group, the infinite U Hubbard model—with one hole doped away from half filling—in triangular and square lattices with frustrated hoppings, which invalidate Nagaoka's theorem. We find that these kinetically frustrated models have antiferromagnetic ground states with classical local magnetization in the thermodynamic limit. We identify the mechanism of this kinetic antiferromagnetism with the release of the kinetic energy frustration, as the hole moves in the established antiferromagnetic background. This release can occur in two different ways: by a nontrivial spin Berry phase acquired by the hole, or by the effective vanishing of the hopping amplitude along the frustrating loops.

  9. Prediction Model for Relativistic Electrons at Geostationary Orbit

    Science.gov (United States)

    Khazanov, George V.; Lyatsky, Wladislaw

    2008-01-01

    We developed a new prediction model for forecasting relativistic (greater than 2MeV) electrons, which provides a VERY HIGH correlation between predicted and actually measured electron fluxes at geostationary orbit. This model implies the multi-step particle acceleration and is based on numerical integrating two linked continuity equations for primarily accelerated particles and relativistic electrons. The model includes a source and losses, and used solar wind data as only input parameters. We used the coupling function which is a best-fit combination of solar wind/interplanetary magnetic field parameters, responsible for the generation of geomagnetic activity, as a source. The loss function was derived from experimental data. We tested the model for four year period 2004-2007. The correlation coefficient between predicted and actual values of the electron fluxes for whole four year period as well as for each of these years is stable and incredibly high (about 0.9). The high and stable correlation between the computed and actual electron fluxes shows that the reliable forecasting these electrons at geostationary orbit is possible.

  10. Modeling and simulation of electronic structure, material interface and random doping in nano-electronic devices

    International Nuclear Information System (INIS)

    Chen Duan; Wei Guowei

    2010-01-01

    The miniaturization of nano-scale electronic devices, such as metal oxide semiconductor field effect transistors (MOSFETs), has given rise to a pressing demand in the new theoretical understanding and practical tactic for dealing with quantum mechanical effects in integrated circuits. Modeling and simulation of this class of problems have emerged as an important topic in applied and computational mathematics. This work presents mathematical models and computational algorithms for the simulation of nano-scale MOSFETs. We introduce a unified two-scale energy functional to describe the electrons and the continuum electrostatic potential of the nano-electronic device. This framework enables us to put microscopic and macroscopic descriptions in an equal footing at nano-scale. By optimization of the energy functional, we derive consistently coupled Poisson-Kohn-Sham equations. Additionally, layered structures are crucial to the electrostatic and transport properties of nano-transistors. A material interface model is proposed for more accurate description of the electrostatics governed by the Poisson equation. Finally, a new individual dopant model that utilizes the Dirac delta function is proposed to understand the random doping effect in nano-electronic devices. Two mathematical algorithms, the matched interface and boundary (MIB) method and the Dirichlet-to-Neumann mapping (DNM) technique, are introduced to improve the computational efficiency of nano-device simulations. Electronic structures are computed via subband decomposition and the transport properties, such as the I-V curves and electron density, are evaluated via the non-equilibrium Green's functions (NEGF) formalism. Two distinct device configurations, a double-gate MOSFET and a four-gate MOSFET, are considered in our three-dimensional numerical simulations. For these devices, the current fluctuation and voltage threshold lowering effect induced by the discrete dopant model are explored. Numerical convergence

  11. A Conceptual Modeling Approach for OLAP Personalization

    Science.gov (United States)

    Garrigós, Irene; Pardillo, Jesús; Mazón, Jose-Norberto; Trujillo, Juan

    Data warehouses rely on multidimensional models in order to provide decision makers with appropriate structures to intuitively analyze data with OLAP technologies. However, data warehouses may be potentially large and multidimensional structures become increasingly complex to be understood at a glance. Even if a departmental data warehouse (also known as data mart) is used, these structures would be also too complex. As a consequence, acquiring the required information is more costly than expected and decision makers using OLAP tools may get frustrated. In this context, current approaches for data warehouse design are focused on deriving a unique OLAP schema for all analysts from their previously stated information requirements, which is not enough to lighten the complexity of the decision making process. To overcome this drawback, we argue for personalizing multidimensional models for OLAP technologies according to the continuously changing user characteristics, context, requirements and behaviour. In this paper, we present a novel approach to personalizing OLAP systems at the conceptual level based on the underlying multidimensional model of the data warehouse, a user model and a set of personalization rules. The great advantage of our approach is that a personalized OLAP schema is provided for each decision maker contributing to better satisfy their specific analysis needs. Finally, we show the applicability of our approach through a sample scenario based on our CASE tool for data warehouse development.

  12. Modeling the customer in electronic commerce.

    Science.gov (United States)

    Helander, M G; Khalid, H M

    2000-12-01

    This paper reviews interface design of web pages for e-commerce. Different tasks in e-commerce are contrasted. A systems model is used to illustrate the information flow between three subsystems in e-commerce: store environment, customer, and web technology. A customer makes several decisions: to enter the store, to navigate, to purchase, to pay, and to keep the merchandize. This artificial environment must be designed so that it can support customer decision-making. To retain customers it must be pleasing and fun, and create a task with natural flow. Customers have different needs, competence and motivation, which affect decision-making. It may therefore be important to customize the design of the e-store environment. Future ergonomics research will have to investigate perceptual aspects, such as presentation of merchandize, and cognitive issues, such as product search and navigation, as well as decision making while considering various economic parameters. Five theories on e-commerce research are presented.

  13. A New Perspective for Modeling Power Electronics Converters : Complementarity Framework

    NARCIS (Netherlands)

    Vasca, Francesco; Iannelli, Luigi; Camlibel, M. Kanat; Frasca, Roberto

    2009-01-01

    The switching behavior of power converters with "ideal" electronic devices (EDs) makes it difficult to define a switched model that describes the dynamics of the converter in all possible operating conditions, i.e., a "complete" model. Indeed, simplifying assumptions on the sequences of modes are

  14. Test of theoretical models for ultrafast heterogeneous electron ...

    Indian Academy of Sciences (India)

    Administrator

    with the predictions of different theoretical models for light-induced ultrafast heterogeneous electron transfer (HET). ... theory model based on molecular dynamics simulations for the vibrational modes were also considered. Based on the known vibrational .... Pseudo 3D map of a 2PPE measurement with. Pe' achored via the ...

  15. Modeling paraxial wave propagation in free-electron laser oscillators

    NARCIS (Netherlands)

    Karssenberg, J.G.; van der Slot, Petrus J.M.; Volokhine, I.; Verschuur, Jeroen W.J.; Boller, Klaus J.

    2006-01-01

    Modeling free-electron laser (FEL) oscillators requires calculation of both the light-beam interaction within the undulator and the light propagation outside the undulator. We have developed a paraxial optical propagation code that can be combined with various existing models of gain media, for

  16. Spin delocalization phase transition in a correlated electrons model

    International Nuclear Information System (INIS)

    Huerta, L.

    1990-11-01

    In a simplified one-site model for correlated electrons systems we show the existence of a phase transition corresponding to spin delocalization. The system becomes a solvable model and zero-dimensional functional techniques are used. (author). 7 refs, 3 figs

  17. Alternate approaches to future electron-positron linear colliders

    International Nuclear Information System (INIS)

    Loew, G.A.

    1998-01-01

    The purpose of this article is two-fold: to review the current international status of various design approaches to the next generation of e + e - linear colliders, and on the occasion of his 80th birthday, to celebrate Richard B. Neal's many contributions to the field of linear accelerators. As it turns out, combining these two tasks is a rather natural enterprise because of Neal's long professional involvement and insight into many of the problems and options which the international e + e - linear collider community is currently studying to achieve a practical design for a future machine

  18. Alternate approaches to future electron-positron linear colliders

    Energy Technology Data Exchange (ETDEWEB)

    Loew, G.A. [Stanford Univ., CA (United States). Stanford Linear Accelerator Center

    1998-07-01

    The purpose of this article is two-fold: to review the current international status of various design approaches to the next generation of e{sup +}e{sup {minus}} linear colliders, and on the occasion of his 80th birthday, to celebrate Richard B. Neal`s many contributions to the field of linear accelerators. As it turns out, combining these two tasks is a rather natural enterprise because of Neal`s long professional involvement and insight into many of the problems and options which the international e{sup +}e{sup {minus}} linear collider community is currently studying to achieve a practical design for a future machine.

  19. Neural network approaches for noisy language modeling.

    Science.gov (United States)

    Li, Jun; Ouazzane, Karim; Kazemian, Hassan B; Afzal, Muhammad Sajid

    2013-11-01

    Text entry from people is not only grammatical and distinct, but also noisy. For example, a user's typing stream contains all the information about the user's interaction with computer using a QWERTY keyboard, which may include the user's typing mistakes as well as specific vocabulary, typing habit, and typing performance. In particular, these features are obvious in disabled users' typing streams. This paper proposes a new concept called noisy language modeling by further developing information theory and applies neural networks to one of its specific application-typing stream. This paper experimentally uses a neural network approach to analyze the disabled users' typing streams both in general and specific ways to identify their typing behaviors and subsequently, to make typing predictions and typing corrections. In this paper, a focused time-delay neural network (FTDNN) language model, a time gap model, a prediction model based on time gap, and a probabilistic neural network model (PNN) are developed. A 38% first hitting rate (HR) and a 53% first three HR in symbol prediction are obtained based on the analysis of a user's typing history through the FTDNN language modeling, while the modeling results using the time gap prediction model and the PNN model demonstrate that the correction rates lie predominantly in between 65% and 90% with the current testing samples, and 70% of all test scores above basic correction rates, respectively. The modeling process demonstrates that a neural network is a suitable and robust language modeling tool to analyze the noisy language stream. The research also paves the way for practical application development in areas such as informational analysis, text prediction, and error correction by providing a theoretical basis of neural network approaches for noisy language modeling.

  20. MODEL OF ELECTRON CLOUD INSTABILITY IN FERMILAB RECYCLER

    Energy Technology Data Exchange (ETDEWEB)

    Antipov, Sergey A. [Chicago U.; Burov, A. [Fermilab; Nagaitsev, S. [Fermilab

    2016-10-04

    An electron cloud instability might limit the intensity in the Fermilab Recycler after the PIP-II upgrade. A multibunch instability typically develops in the horizontal plane within a hundred turns and, in certain conditions, leads to beam loss. Recent studies have indicated that the instability is caused by an electron cloud, trapped in the Recycler index dipole magnets. We developed an analytical model of an electron cloud driven instability with the electrons trapped in combined function dipoles. The resulting instability growth rate of about 30 revolutions is consistent with experimental observations and qualitatively agrees with the simulation in the PEI code. The model allows an estimation of the instability rate for the future intensity upgrades.

  1. Modelling hot electron generation in short pulse target heating experiments

    Directory of Open Access Journals (Sweden)

    Sircombe N.J.

    2013-11-01

    Full Text Available Target heating experiments planned for the Orion laser facility, and electron beam driven fast ignition schemes, rely on the interaction of a short pulse high intensity laser with dense material to generate a flux of energetic electrons. It is essential that the characteristics of this electron source are well known in order to inform transport models in radiation hydrodynamics codes and allow effective evaluation of experimental results and forward modelling of future campaigns. We present results obtained with the particle in cell (PIC code EPOCH for realistic target and laser parameters, including first and second harmonic light. The hot electron distributions are characterised and their implications for onward transport and target heating are considered with the aid of the Monte-Carlo transport code THOR.

  2. Dimensionality of electronic excitations in organic semiconductors: A dielectric function approach

    Science.gov (United States)

    Campoy-Quiles, Mariano; Nelson, Jenny; Bradley, Donal D. C.; Etchegoin, Pablo G.

    2007-12-01

    We present a detailed investigation on the effective dimensionality (associated with the degree of delocalization) of electronic excitations in thin organic films using the dielectric function as obtained from ellipsometry. To this end, we study first the best analytical representation of the optical dielectric function of these materials and compare different approaches found in the literature: (i) the harmonic oscillator approximation, (ii) the standard critical-point model (SCP), (iii) the model dielectric function (MDF), and (iv) the Forouhi-Bloomer model. We use these models to analyze variable angle spectroscopic ellipsometry raw data for a thin poly(9,9-dioctylfluorene) (PFO) film deposited on quartz (taken as an archetypal sample). The superiority of the SCP model for PFO films and a wide range of other spin-coated conjugated polymers (and guest-molecules in polymers) is demonstrated. Moreover, we show how the SCP model can be used to gain physical information on the microscopic structure. As an example, we show that the delocalization of excitons decreases for nonconjugated polymers, such as polymethylmethacrylate and polyimide, while the conjugation length and exciton delocalization are, respectively, enhanced in cases where a planar conformation (e.g., β phase of PFO) or a high degree of crystallinity [e.g., poly(3-hexylthiophene)] is achieved. As an additional example, we employ the SCP excitonic model to investigate the temperature dependence of the dielectric function of crystalline and glassy PFO films. We propose that the SCP excitonic model should be adopted as the standard choice to model the optical properties of polymer thin films from ellipsometry data.

  3. Transformer Model in Wide Frequency Bandwidth for Power Electronics Systems

    OpenAIRE

    Gonzalez-Garcia, Carlos; Pleite, Jorge

    2013-01-01

    The development of the smart grids leads to new challenges on the power electronics equipment and power transformers. The use of power electronic transformer presents several advantages, but new problems related with the application of high frequency voltage and current components come across. Thus, an accurate knowledge of the transformer behavior in a wide frequency range is mandatory. A novel modeling procedure to relate the transformer physical behavior and its frequency response by means...

  4. Heat transfer modeling an inductive approach

    CERN Document Server

    Sidebotham, George

    2015-01-01

    This innovative text emphasizes a "less-is-more" approach to modeling complicated systems such as heat transfer by treating them first as "1-node lumped models" that yield simple closed-form solutions. The author develops numerical techniques for students to obtain more detail, but also trains them to use the techniques only when simpler approaches fail. Covering all essential methods offered in traditional texts, but with a different order, Professor Sidebotham stresses inductive thinking and problem solving as well as a constructive understanding of modern, computer-based practice. Readers learn to develop their own code in the context of the material, rather than just how to use packaged software, offering a deeper, intrinsic grasp behind models of heat transfer. Developed from over twenty-five years of lecture notes to teach students of mechanical and chemical engineering at The Cooper Union for the Advancement of Science and Art, the book is ideal for students and practitioners across engineering discipl...

  5. QUANTITATIVE ELECTRONIC STRUCTURE - ACTIVITY RELATIONSHIP OF ANTIMALARIAL COMPOUND OF ARTEMISININ DERIVATIVES USING PRINCIPAL COMPONENT REGRESSION APPROACH

    Directory of Open Access Journals (Sweden)

    Paul Robert Martin Werfette

    2010-06-01

    Full Text Available Analysis of quantitative structure - activity relationship (QSAR for a series of antimalarial compound artemisinin derivatives has been done using principal component regression. The descriptors for QSAR study were representation of electronic structure i.e. atomic net charges of the artemisinin skeleton calculated by AM1 semi-empirical method. The antimalarial activity of the compound was expressed in log 1/IC50 which is an experimental data. The main purpose of the principal component analysis approach is to transform a large data set of atomic net charges to simplify into a data set which known as latent variables. The best QSAR equation to analyze of log 1/IC50 can be obtained from the regression method as a linear function of several latent variables i.e. x1, x2, x3, x4 and x5. The best QSAR model is expressed in the following equation,  (;;   Keywords: QSAR, antimalarial, artemisinin, principal component regression

  6. A ballistic transport model for electronic excitation following particle impact

    Science.gov (United States)

    Hanke, S.; Heuser, C.; Weidtmann, B.; Wucher, A.

    2018-01-01

    We present a ballistic model for the transport of electronic excitation energy induced by keV particle bombardment onto a solid surface. Starting from a free electron gas model, the Boltzmann transport equation (BTE) is employed to follow the evolution of the temporal and spatial distribution function f (r → , k → , t) describing the occupation probability of an electronic state k → at position r → and time t. Three different initializations of the distribution function are considered: i) a thermal distribution function with a locally and temporally elevated electron temperature, ii) a peak excitation at a specific energy above the Fermi level with a quasi-isotropic distribution in k-space and iii) an anisotropic peak excitation with k-vectors oriented in a specific transport direction. While the first initialization resembles a distribution function which may, for instance, result from electronic friction of moving atoms within an ion induced collision cascade, the peak excitation can in principle result from an autoionization process after excitation in close binary collisions. By numerically solving the BTE, we study the electronic energy exchange along a one dimensional transport direction to obtain a time and space resolved excitation energy distribution function, which is then analyzed in view of general transport characteristics of the chosen model system.

  7. Optimization of electronic enclosure design for thermal and moisture management using calibrated models of progressive complexity

    DEFF Research Database (Denmark)

    Mohanty, Sankhya; Staliulionis, Zygimantas; Shojaee Nasirabadi, Parizad

    2016-01-01

    The thermal and moisture management of electronic enclosures are fields of high interest in recent years. It is now generally accepted that the protection of electronic devices is dependent on avoiding critical levels of relative humidity (typically 60–90%) during operations. Leveraging...... focus the parameter-value space, before shifting to 3D CFD models for final evaluations and verification. The approach results in a system capable of predicting optimum design features for the thermal and moisture management of electronic enclosures in a time-efficient and practically implementable...... the development of rigorous calibrated CFD models as well as simple predictive numerical tools, the current paper tackles the optimization of critical features of a typical two-chamber electronic enclosure. The progressive optimization strategy begins the design parameter selection by initially using simpler...

  8. Photoemission in strongly correlated crystalline f-electron systems: A need for a new approach

    Energy Technology Data Exchange (ETDEWEB)

    Arko, A.J.; Joyce, J.J.; Sarrao, J. [and others

    1998-12-01

    The unusual properties of heavy fermion (or heavy electron) materials have sparked an avalanche of research over the last two decades in order to understand the basic phenomena responsible for these properties. Photoelectron spectroscopy (often referred to as PES in the following sections), the most direct measurement of the electronic structure of a material, should in principle be able to shed considerable light on this matter. In general the distinction between a localized and a band-like state is trivially observed in band dispersion. Much of the past work was performed on poly-crystalline samples, scraped in-situ to expose a clean surface for PES. There have since been considerable advances both in the quality of specimens as well as experimental resolution, which raise questions regarding these conclusions. Much of the past work on poly-crystalline samples has been reported in several review articles, most notably Allen et al., and it is not necessary here to review those efforts again, with the exception of subsequent work performed at high resolution. The primary focus of the present review will be on new measurements obtained on single crystals, cleaved or prepared in situ and measured at high resolution, which seem to suggest that agreement with the GS and NCA approximations is less than perfect, and that perhaps the starting models need to be modified, or that even an entirely new approach is called for. Of the promising new models the Periodic Anderson Model is most closely related to the SIM. Indeed, at high temperatures it reverts to the SIM. However, the charge polaron model of Liu (1997) as well as the two-electron band model of Sheng and Cooper (1995) cannot yet be ruled out. Inasmuch as the bulk of the single crystal work was performed by the Los Alamos group, this review will draw heavily on those results. Moreover, since the GS and NCA approximations represent the most comprehensive and widely accepted treatment of heavy fermion PES, it is only

  9. A novel approach for honey pollen profile assessment using an electronic tongue and chemometric tools

    International Nuclear Information System (INIS)

    Dias, Luís G.; Veloso, Ana C.A.; Sousa, Mara E.B.C.; Estevinho, Letícia; Machado, Adélio A.S.C.

    2015-01-01

    Nowadays the main honey producing countries require accurate labeling of honey before commercialization, including floral classification. Traditionally, this classification is made by melissopalynology analysis, an accurate but time-consuming task requiring laborious sample pre-treatment and high-skilled technicians. In this work the potential use of a potentiometric electronic tongue for pollinic assessment is evaluated, using monofloral and polyfloral honeys. The results showed that after splitting honeys according to color (white, amber and dark), the novel methodology enabled quantifying the relative percentage of the main pollens (Castanea sp., Echium sp., Erica sp., Eucaliptus sp., Lavandula sp., Prunus sp., Rubus sp. and Trifolium sp.). Multiple linear regression models were established for each type of pollen, based on the best sensors' sub-sets selected using the simulated annealing algorithm. To minimize the overfitting risk, a repeated K-fold cross-validation procedure was implemented, ensuring that at least 10–20% of the honeys were used for internal validation. With this approach, a minimum average determination coefficient of 0.91 ± 0.15 was obtained. Also, the proposed technique enabled the correct classification of 92% and 100% of monofloral and polyfloral honeys, respectively. The quite satisfactory performance of the novel procedure for quantifying the relative pollen frequency may envisage its applicability for honey labeling and geographical origin identification. Nevertheless, this approach is not a full alternative to the traditional melissopalynologic analysis; it may be seen as a practical complementary tool for preliminary honey floral classification, leaving only problematic cases for pollinic evaluation. - Highlights: • Honey's floral origin labeling is a legal requirement. • Melissopalynology analysis usually used to evaluate pollens profile is laborious. • A novel E-tongue based approach is applied to assess pollens

  10. A novel approach for honey pollen profile assessment using an electronic tongue and chemometric tools

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Luís G., E-mail: ldias@ipb.pt [Escola Superior Agrária, Instituto Politécnico de Bragança, Campus Santa Apolónia, 5301-855 Bragança (Portugal); CQ-VR, Centro de Química – Vila Real, University of Trás-os-Montes e Alto Douro, Apartado 1013, 5001-801 Vila Real (Portugal); Veloso, Ana C.A. [Instituto Politécnico de Coimbra, ISEC, DEQB, Rua Pedro Nunes, Quinta da Nora, 3030-199 Coimbra (Portugal); CEB-Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Sousa, Mara E.B.C.; Estevinho, Letícia [CIMO-Escola Superior Agrária, Instituto Politécnico de Bragança, Campus Santa Apolónia, 5301-855 Bragança (Portugal); Machado, Adélio A.S.C. [LAQUIPAI – Laboratório de Química Inorgânica Pura e de Aplicação Interdisciplinar, Departamento de Química, Faculdade de Ciências da, Universidade do Porto, Rua Campo Alegre n°. 687, 4169-007 Porto (Portugal); and others

    2015-11-05

    Nowadays the main honey producing countries require accurate labeling of honey before commercialization, including floral classification. Traditionally, this classification is made by melissopalynology analysis, an accurate but time-consuming task requiring laborious sample pre-treatment and high-skilled technicians. In this work the potential use of a potentiometric electronic tongue for pollinic assessment is evaluated, using monofloral and polyfloral honeys. The results showed that after splitting honeys according to color (white, amber and dark), the novel methodology enabled quantifying the relative percentage of the main pollens (Castanea sp., Echium sp., Erica sp., Eucaliptus sp., Lavandula sp., Prunus sp., Rubus sp. and Trifolium sp.). Multiple linear regression models were established for each type of pollen, based on the best sensors' sub-sets selected using the simulated annealing algorithm. To minimize the overfitting risk, a repeated K-fold cross-validation procedure was implemented, ensuring that at least 10–20% of the honeys were used for internal validation. With this approach, a minimum average determination coefficient of 0.91 ± 0.15 was obtained. Also, the proposed technique enabled the correct classification of 92% and 100% of monofloral and polyfloral honeys, respectively. The quite satisfactory performance of the novel procedure for quantifying the relative pollen frequency may envisage its applicability for honey labeling and geographical origin identification. Nevertheless, this approach is not a full alternative to the traditional melissopalynologic analysis; it may be seen as a practical complementary tool for preliminary honey floral classification, leaving only problematic cases for pollinic evaluation. - Highlights: • Honey's floral origin labeling is a legal requirement. • Melissopalynology analysis usually used to evaluate pollens profile is laborious. • A novel E-tongue based approach is applied to assess pollens

  11. Teaching Electronic Literacy A Concepts-Based Approach for School Library Media Specialists

    CERN Document Server

    Craver, Kathleen W

    1997-01-01

    School library media specialists will find this concepts-based approach to teaching electronic literacy an indispensable basic tool for instructing students and teachers. It provides step-by-step instruction on how to find and evaluate needed information from electronic databases and the Internet, how to formulate successful electronic search strategies and retrieve relevant results, and how to interpret and critically analyze search results. The chapters contain a suggested lesson plan and sample assignments for the school library media specialist to use in teaching electronic literacy skills

  12. A multiscale modeling approach for biomolecular systems

    Energy Technology Data Exchange (ETDEWEB)

    Bowling, Alan, E-mail: bowling@uta.edu; Haghshenas-Jaryani, Mahdi, E-mail: mahdi.haghshenasjaryani@mavs.uta.edu [The University of Texas at Arlington, Department of Mechanical and Aerospace Engineering (United States)

    2015-04-15

    This paper presents a new multiscale molecular dynamic model for investigating the effects of external interactions, such as contact and impact, during stepping and docking of motor proteins and other biomolecular systems. The model retains the mass properties ensuring that the result satisfies Newton’s second law. This idea is presented using a simple particle model to facilitate discussion of the rigid body model; however, the particle model does provide insights into particle dynamics at the nanoscale. The resulting three-dimensional model predicts a significant decrease in the effect of the random forces associated with Brownian motion. This conclusion runs contrary to the widely accepted notion that the motor protein’s movements are primarily the result of thermal effects. This work focuses on the mechanical aspects of protein locomotion; the effect ATP hydrolysis is estimated as internal forces acting on the mechanical model. In addition, the proposed model can be numerically integrated in a reasonable amount of time. Herein, the differences between the motion predicted by the old and new modeling approaches are compared using a simplified model of myosin V.

  13. Quasirelativistic quark model in quasipotential approach

    CERN Document Server

    Matveev, V A; Savrin, V I; Sissakian, A N

    2002-01-01

    The relativistic particles interaction is described within the frames of quasipotential approach. The presentation is based on the so called covariant simultaneous formulation of the quantum field theory, where by the theory is considered on the spatial-like three-dimensional hypersurface in the Minkowski space. Special attention is paid to the methods of plotting various quasipotentials as well as to the applications of the quasipotential approach to describing the characteristics of the relativistic particles interaction in the quark models, namely: the hadrons elastic scattering amplitudes, the mass spectra and widths mesons decays, the cross sections of the deep inelastic leptons scattering on the hadrons

  14. New Statistical Multiparticle Approach to the Acceleration of Electrons by the Ion Field in Plasmas

    Directory of Open Access Journals (Sweden)

    Eugene Oks

    2010-01-01

    Full Text Available The phenomenon of the acceleration of the (perturbing electrons by the ion field (AEIF significantly reduces Stark widths and shifts in plasmas of relatively high densities and/or relatively low temperature. Our previous analytical calculations of the AEIF were based on the dynamical treatment: the starting point was the ion-microfield-caused changes of the trajectories and velocities of individual perturbing electrons. In the current paper, we employ a statistical approach: the starting point is the electron velocity distribution function modified by the ion microfield. The latter had been calculated by Romanovsky and Ebeling in the multiparticle description of the ion microfield. The result shows again the reduction of the electron Stark broadening. Thus two totally different analytical approaches (dynamical and statistical agree with each other and therefore disprove the corresponding recent fully-numerical simulations by Stambulchik et al. that claimed an increase of the electron Stark broadening.

  15. Detailed modeling of electron emission for transpiration cooling of hypersonic vehicles

    Science.gov (United States)

    Hanquist, Kyle M.; Hara, Kentaro; Boyd, Iain D.

    2017-02-01

    Electron transpiration cooling (ETC) is a recently proposed approach to manage the high heating loads experienced at the sharp leading edges of hypersonic vehicles. Computational fluid dynamics (CFD) can be used to investigate the feasibility of ETC in a hypersonic environment. A modeling approach is presented for ETC, which includes developing the boundary conditions for electron emission from the surface, accounting for the space-charge limit effects of the near-wall plasma sheath. The space-charge limit models are assessed using 1D direct-kinetic plasma sheath simulations, taking into account the thermionically emitted electrons from the surface. The simulations agree well with the space-charge limit theory proposed by Takamura et al. for emitted electrons with a finite temperature, especially at low values of wall bias, which validates the use of the theoretical model for the hypersonic CFD code. The CFD code with the analytical sheath models is then used for a test case typical of a leading edge radius in a hypersonic flight environment. The CFD results show that ETC can lower the surface temperature of sharp leading edges of hypersonic vehicles, especially at higher velocities, due to the increase in ionized species enabling higher electron heat extraction from the surface. The CFD results also show that space-charge limit effects can limit the ETC reduction of surface temperatures, in comparison to thermionic emission assuming no effects of the electric field within the sheath.

  16. A new approach for developing adjoint models

    Science.gov (United States)

    Farrell, P. E.; Funke, S. W.

    2011-12-01

    Many data assimilation algorithms rely on the availability of gradients of misfit functionals, which can be efficiently computed with adjoint models. However, the development of an adjoint model for a complex geophysical code is generally very difficult. Algorithmic differentiation (AD, also called automatic differentiation) offers one strategy for simplifying this task: it takes the abstraction that a model is a sequence of primitive instructions, each of which may be differentiated in turn. While extremely successful, this low-level abstraction runs into time-consuming difficulties when applied to the whole codebase of a model, such as differentiating through linear solves, model I/O, calls to external libraries, language features that are unsupported by the AD tool, and the use of multiple programming languages. While these difficulties can be overcome, it requires a large amount of technical expertise and an intimate familiarity with both the AD tool and the model. An alternative to applying the AD tool to the whole codebase is to assemble the discrete adjoint equations and use these to compute the necessary gradients. With this approach, the AD tool must be applied to the nonlinear assembly operators, which are typically small, self-contained units of the codebase. The disadvantage of this approach is that the assembly of the discrete adjoint equations is still very difficult to perform correctly, especially for complex multiphysics models that perform temporal integration; as it stands, this approach is as difficult and time-consuming as applying AD to the whole model. In this work, we have developed a library which greatly simplifies and automates the alternate approach of assembling the discrete adjoint equations. We propose a complementary, higher-level abstraction to that of AD: that a model is a sequence of linear solves. The developer annotates model source code with library calls that build a 'tape' of the operators involved and their dependencies, and

  17. An Open Architecture Framework for Electronic Warfare Based Approach to HLA Federate Development

    Directory of Open Access Journals (Sweden)

    HyunSeo Kang

    2018-01-01

    Full Text Available A variety of electronic warfare models are developed in the Electronic Warfare Research Center. An Open Architecture Framework for Electronic Warfare (OAFEw has been developed for reusability of various object models participating in the electronic warfare simulation and for extensibility of the electronic warfare simulator. OAFEw is a kind of component-based software (SW lifecycle management support framework. This OAFEw is defined by six components and ten rules. The purpose of this study is to construct a Distributed Simulation Interface Model, according to the rules of OAFEw, and create Use Case Model of OAFEw Reference Conceptual Model version 1.0. This is embodied in the OAFEw-FOM (Federate Object Model for High-Level Architecture (HLA based distributed simulation. Therefore, we design and implement EW real-time distributed simulation that can work with a model in C++ and MATLAB API (Application Programming Interface. In addition, OAFEw-FOM, electronic component model, and scenario of the electronic warfare domain were designed through simple scenarios for verification, and real-time distributed simulation between C++ and MATLAB was performed through OAFEw-Distributed Simulation Interface.

  18. Dimer and cluster approach for the evaluation of electronic couplings governing charge transport: Application to two pentacene polymorphs

    Energy Technology Data Exchange (ETDEWEB)

    Canola, Sofia; Pecoraro, Claudia; Negri, Fabrizia

    2016-10-20

    Hole transport properties are modeled for two polymorphs of pentacene: the single crystal polymorph and the thin film polymorph relevant for organic thin-film transistor applications. Electronic couplings are evaluated in the standard dimer approach but also considering a cluster approach in which the central molecule is surrounded by a large number of molecules quantum-chemically described. The effective electronic couplings suitable for the parametrization of a tight-binding model are derived either from the orthogonalization scheme limited to HOMO orbitals and from the orthogonalization of the full basis of molecular orbitals. The angular dependent mobilities estimated for the two polymorphs using the predicted pattern of couplings display different anisotropy characteristics as suggested from experimental investigations.

  19. An equilibrium approach to modelling social interaction

    Science.gov (United States)

    Gallo, Ignacio

    2009-07-01

    The aim of this work is to put forward a statistical mechanics theory of social interaction, generalizing econometric discrete choice models. After showing the formal equivalence linking econometric multinomial logit models to equilibrium statical mechanics, a multi-population generalization of the Curie-Weiss model for ferromagnets is considered as a starting point in developing a model capable of describing sudden shifts in aggregate human behaviour. Existence of the thermodynamic limit for the model is shown by an asymptotic sub-additivity method and factorization of correlation functions is proved almost everywhere. The exact solution of the model is provided in the thermodynamical limit by finding converging upper and lower bounds for the system's pressure, and the solution is used to prove an analytic result regarding the number of possible equilibrium states of a two-population system. The work stresses the importance of linking regimes predicted by the model to real phenomena, and to this end it proposes two possible procedures to estimate the model's parameters starting from micro-level data. These are applied to three case studies based on census type data: though these studies are found to be ultimately inconclusive on an empirical level, considerations are drawn that encourage further refinements of the chosen modelling approach.

  20. Enhanced contrast separation in scanning electron microscopes via a suspended-thin sample approach.

    Science.gov (United States)

    Ji, Yuan; Wang, Li; Guo, Zhenxi; Wei, Bin; Zhao, Jie; Wang, Xiaodong; Zhang, Yinqi; Sui, Manling; Han, Xiaodong

    2014-11-01

    A suspended-thin-sample (STS) approach for signal selection and contrast separation is developed in scanning electron microscopes with commonly used primary beam energies and traditional detectors. Topography contrast, electron channeling contrast and composition contrast are separated and largely enhanced from suspended thin samples of several hundred nanometers in thickness, which is less than the escape depth of backscattered electrons. This imaging technique enables to detect relatively pure secondary electron and elastic backscattered electron singles, whereas suppress multiple inelastic scattering effects. The provided contrast features are different from those of bulk samples, which are largely mixed with inelastic scattering effects. The STS imaging concept and method could be expected to have more applications in distinguishing materials of nanostructures, multilayers, compounds and composites, as well as in SEM-based electron backscatter diffraction, cathodoluminesence, and x-ray microanalysis. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Evolutionary modeling-based approach for model errors correction

    Directory of Open Access Journals (Sweden)

    S. Q. Wan

    2012-08-01

    Full Text Available The inverse problem of using the information of historical data to estimate model errors is one of the science frontier research topics. In this study, we investigate such a problem using the classic Lorenz (1963 equation as a prediction model and the Lorenz equation with a periodic evolutionary function as an accurate representation of reality to generate "observational data."

    On the basis of the intelligent features of evolutionary modeling (EM, including self-organization, self-adaptive and self-learning, the dynamic information contained in the historical data can be identified and extracted by computer automatically. Thereby, a new approach is proposed to estimate model errors based on EM in the present paper. Numerical tests demonstrate the ability of the new approach to correct model structural errors. In fact, it can actualize the combination of the statistics and dynamics to certain extent.

  2. MODELS OF TECHNOLOGY ADOPTION: AN INTEGRATIVE APPROACH

    Directory of Open Access Journals (Sweden)

    Andrei OGREZEANU

    2015-06-01

    Full Text Available The interdisciplinary study of information technology adoption has developed rapidly over the last 30 years. Various theoretical models have been developed and applied such as: the Technology Acceptance Model (TAM, Innovation Diffusion Theory (IDT, Theory of Planned Behavior (TPB, etc. The result of these many years of research is thousands of contributions to the field, which, however, remain highly fragmented. This paper develops a theoretical model of technology adoption by integrating major theories in the field: primarily IDT, TAM, and TPB. To do so while avoiding mess, an approach that goes back to basics in independent variable type’s development is proposed; emphasizing: 1 the logic of classification, and 2 psychological mechanisms behind variable types. Once developed these types are then populated with variables originating in empirical research. Conclusions are developed on which types are underpopulated and present potential for future research. I end with a set of methodological recommendations for future application of the model.

  3. Interfacial Fluid Mechanics A Mathematical Modeling Approach

    CERN Document Server

    Ajaev, Vladimir S

    2012-01-01

    Interfacial Fluid Mechanics: A Mathematical Modeling Approach provides an introduction to mathematical models of viscous flow used in rapidly developing fields of microfluidics and microscale heat transfer. The basic physical effects are first introduced in the context of simple configurations and their relative importance in typical microscale applications is discussed. Then,several configurations of importance to microfluidics, most notably thin films/droplets on substrates and confined bubbles, are discussed in detail.  Topics from current research on electrokinetic phenomena, liquid flow near structured solid surfaces, evaporation/condensation, and surfactant phenomena are discussed in the later chapters. This book also:  Discusses mathematical models in the context of actual applications such as electrowetting Includes unique material on fluid flow near structured surfaces and phase change phenomena Shows readers how to solve modeling problems related to microscale multiphase flows Interfacial Fluid Me...

  4. Continuum modeling an approach through practical examples

    CERN Document Server

    Muntean, Adrian

    2015-01-01

    This book develops continuum modeling skills and approaches the topic from three sides: (1) derivation of global integral laws together with the associated local differential equations, (2) design of constitutive laws and (3) modeling boundary processes. The focus of this presentation lies on many practical examples covering aspects such as coupled flow, diffusion and reaction in porous media or microwave heating of a pizza, as well as traffic issues in bacterial colonies and energy harvesting from geothermal wells. The target audience comprises primarily graduate students in pure and applied mathematics as well as working practitioners in engineering who are faced by nonstandard rheological topics like those typically arising in the food industry.

  5. Status of the Galileo interim radiation electron model

    Science.gov (United States)

    Garrett, H. B.; Jun, I.; Ratliff, J. M.; Evans, R. W.; Clough, G. A.; McEntire, R. W.

    2003-04-01

    Measurements of the high energy, omni-directional electron environment by the Galileo spacecraft Energetic Particle Detector (EPD) were used to develop a new model of Jupiter's trapped electron radiation in the jovian equatorial plane for the range 8 to 16 Jupiter radii (1 jovian radius = 71,400 km). 10-minute averages of these data formed an extensive database of observations of the jovian radiation belts between Jupiter orbit insertion (JOI) in 1995 and 2002. These data were then averaged to provide a differential flux spectrum at 0.174, 0.304, 0.527, 1.5, 2.0, 11.0, and 31 MeV in the jovian equatorial plane as a function of radial distance. This omni-directional, equatorial model was combined with the original Divine model of jovian electron radiation to yield estimates of the out-of-plane radiation environment. That model, referred to here as the Galileo Interim Radiation Electron (or GIRE) model, was then used to calculate the Europa mission dose for an average and a 1-sigma worst-case situation. The prediction of the GIRE model is about a factor of 2 lower than the Divine model estimate over the range of 100 to 1000 mils (2.54 to 25.4 mm) of aluminum shielding, but exceeds the Divine model by about 50% for thicker shielding. The model, the steps leading to its creation, and relevant issues and concerns are discussed. While work remains to be done, the GIRE model clearly represents a significant step forward in the study of the jovian radiation environment, and it is a useful and valuable tool for estimating that environment for future space missions.

  6. 3D Modeling Activity for Novel High Power Electron Guns at SLAC

    CERN Document Server

    Krasnykh, Anatoly K

    2003-01-01

    The next generation of powerful electronic devices requires new approaches to overcome the known limitations of existing tube technology. Multi-beam and sheet beam approaches are novel concepts for the high power microwave devices. Direct and indirect modeling methods are being developed at SLAC to meet the new requirements in the 3D modeling. The direct method of solving of Poisson's equations for the multi-beam and sheet beam guns is employed in the TOPAZ 3D tool. The combination of TOPAZ 2D and EGUN (in the beginning) with MAFIA 3D and MAGIC 3D (at the end) is used in an indirect method to model the high power electron guns. Both methods complement each other to get reliable representation of the beam trajectories. Several gun ideas are under consideration at the present time. The collected results of these simulations are discussed.

  7. Modelling and simulation of beam formation in electron guns

    International Nuclear Information System (INIS)

    Sabchevski, S.; Barbarich, I.

    1996-01-01

    This paper describes a new PC version of the software package GUN-EBT for computer simulation of beam formation in rotationally symmetric electron guns with thermionic cathodes. It is based on a self-consistent physical model which takes into account the beam space charge and the initial velocity effects. The theoretical framework used for both the formulation of the model and for the interpretation of the results of numerical experiments is the formalism of the charged particle dynamics in phase space. This enables not only a trajectory analysis (ray tracing) but also a phase-space analysis of beams to be performed. The package can be used as an effective tool for computer aided design and optimization of electron guns in various electron-optical systems. The operation of the package is illustrated with a typical example. (orig.)

  8. Modelling and simulation of beam formation in electron guns

    Energy Technology Data Exchange (ETDEWEB)

    Sabchevski, S. [Bulgarian Academy of Sciences, Sofia (Bulgaria). Inst. po Elektronika; Mladenov, G. [Bulgarian Academy of Sciences, Sofia (Bulgaria). Inst. po Elektronika; Titov, A. [St. Petersburg State Electrotechnical University, St. Petersburg (Russian Federation); Barbarich, I. [St. Petersburg State Electrotechnical University, St. Petersburg (Russian Federation)

    1996-11-01

    This paper describes a new PC version of the software package GUN-EBT for computer simulation of beam formation in rotationally symmetric electron guns with thermionic cathodes. It is based on a self-consistent physical model which takes into account the beam space charge and the initial velocity effects. The theoretical framework used for both the formulation of the model and for the interpretation of the results of numerical experiments is the formalism of the charged particle dynamics in phase space. This enables not only a trajectory analysis (ray tracing) but also a phase-space analysis of beams to be performed. The package can be used as an effective tool for computer aided design and optimization of electron guns in various electron-optical systems. The operation of the package is illustrated with a typical example. (orig.).

  9. Datamining approaches for modeling tumor control probability.

    Science.gov (United States)

    Naqa, Issam El; Deasy, Joseph O; Mu, Yi; Huang, Ellen; Hope, Andrew J; Lindsay, Patricia E; Apte, Aditya; Alaly, James; Bradley, Jeffrey D

    2010-11-01

    Tumor control probability (TCP) to radiotherapy is determined by complex interactions between tumor biology, tumor microenvironment, radiation dosimetry, and patient-related variables. The complexity of these heterogeneous variable interactions constitutes a challenge for building predictive models for routine clinical practice. We describe a datamining framework that can unravel the higher order relationships among dosimetric dose-volume prognostic variables, interrogate various radiobiological processes, and generalize to unseen data before when applied prospectively. Several datamining approaches are discussed that include dose-volume metrics, equivalent uniform dose, mechanistic Poisson model, and model building methods using statistical regression and machine learning techniques. Institutional datasets of non-small cell lung cancer (NSCLC) patients are used to demonstrate these methods. The performance of the different methods was evaluated using bivariate Spearman rank correlations (rs). Over-fitting was controlled via resampling methods. Using a dataset of 56 patients with primary NCSLC tumors and 23 candidate variables, we estimated GTV volume and V75 to be the best model parameters for predicting TCP using statistical resampling and a logistic model. Using these variables, the support vector machine (SVM) kernel method provided superior performance for TCP prediction with an rs=0.68 on leave-one-out testing compared to logistic regression (rs=0.4), Poisson-based TCP (rs=0.33), and cell kill equivalent uniform dose model (rs=0.17). The prediction of treatment response can be improved by utilizing datamining approaches, which are able to unravel important non-linear complex interactions among model variables and have the capacity to predict on unseen data for prospective clinical applications.

  10. Electronic and magnetic properties of UPdSn: the itinerant 5f electrons approach

    CERN Document Server

    Sandratskii, L M

    1997-01-01

    Density functional theory, modified to include spin-orbit coupling and an effective orbital field to simulate Hound's second rule, is applied to investigate the magnetic structure and electronic properties of the compound Upends. Our theoretical results are in overall good agreement with experiment. Thus both theory and experiment find the magnetic structure of Upends to be non collinear, the calculated magnetic U-moments being in very good agreement with the measurements. Also, the calculated density of states is found to simulate closely the photoemission spectrum and the very low experimental value of 5 mJ mol sup - sup 1 K sup - sup 2 for the specific heat gamma is reproduced reasonably well by the calculated value of 7.5 mJ mol sup - sup 1 K sup - sup 2. Furthermore, the interconnection of the magnetic structure with the crystal structure is investigated. Here theory and experiment agree concerning the planar non collinear antiferromagnetic configuration in the orthorhombic crystal structure and for the ...

  11. Toward a generic model of trust for electronic commerce

    NARCIS (Netherlands)

    Tan, YH; Thoen, W

    2000-01-01

    The authors present a generic model of trust for electronic commerce consisting of two basic components, party trust and control trust, based on the concept that trust in a transaction with another party combines trust in the other parry and trust in the control mechanisms that ensure the successful

  12. Technical Communicator: A New Model for the Electronic Resources Librarian?

    Science.gov (United States)

    Hulseberg, Anna

    2016-01-01

    This article explores whether technical communicator is a useful model for electronic resources (ER) librarians. The fields of ER librarianship and technical communication (TC) originated and continue to develop in relation to evolving technologies. A review of the literature reveals four common themes for ER librarianship and TC. While the…

  13. Classical model of the Dirac electron in curved space

    International Nuclear Information System (INIS)

    Barut, A.O.; Pavsic, M.

    1987-01-01

    The action for the classical model of the electron exhibiting Zitterbewegung is generalized to curved space by introducing a spin connection. The dynamical equations and the symplectic structure are given for several different choices of the variables. In particular, we obtain the equation of motion for spin and compare it with the Papapetrou equation. (author)

  14. A new model of dependence of secondary electron emission yield on primary electron energy for application to polymers

    Energy Technology Data Exchange (ETDEWEB)

    Cazaux, J [LASSI/UTAP, Faculte des Sciences, BP1039, 51687 Reims Cedex 2 (France)

    2005-07-21

    A new analytical model for the secondary electron (SE) emission yield, {delta}, is applied to polymers. It involves a parameter k, k = z{sub C}/R, between the most probable energy dissipation depth, z{sub C}, of primary electrons (PE) and their range R, where k ranges from 0.5 and 0.45 for low-density, low atomic-weight materials. Reduced yield curves (RYC), {delta}/{delta}{sub (max)} versus E{sup 0}/E{sup 0}{sub (max)}, and normal yield curves, {delta} versus E{sup 0}, obtained from published experimental data on a wide variety of polymers (polystyrene, PET, polyimide; Kapton; PTFE; Teflon, PMMA, nylon, polyurethane) are compared with the calculated change of {delta} with PE energy, E{sup 0}. In contrast to the use of the conventional constant loss model where the best fit requires an empirical change in the exponent 'n' in the power law expression of the PE range, R versus E{sup 0}, the present approach is based on the usual choice for n, n = 1.35, and on a choice for k governed by physical arguments. This physical basis then enables one to predict the RYC of other polymers. Finally, values of the SE escape probability and SE attenuation length are estimated for the polymers of interest and a new mechanism is suggested for the contrast reversal in scanning electron microscopy.

  15. A new model of dependence of secondary electron emission yield on primary electron energy for application to polymers

    International Nuclear Information System (INIS)

    Cazaux, J

    2005-01-01

    A new analytical model for the secondary electron (SE) emission yield, δ, is applied to polymers. It involves a parameter k, k = z C /R, between the most probable energy dissipation depth, z C , of primary electrons (PE) and their range R, where k ranges from 0.5 and 0.45 for low-density, low atomic-weight materials. Reduced yield curves (RYC), δ/δ (max) versus E 0 /E 0 (max) , and normal yield curves, δ versus E 0 , obtained from published experimental data on a wide variety of polymers (polystyrene, PET, polyimide; Kapton; PTFE; Teflon, PMMA, nylon, polyurethane) are compared with the calculated change of δ with PE energy, E 0 . In contrast to the use of the conventional constant loss model where the best fit requires an empirical change in the exponent 'n' in the power law expression of the PE range, R versus E 0 , the present approach is based on the usual choice for n, n = 1.35, and on a choice for k governed by physical arguments. This physical basis then enables one to predict the RYC of other polymers. Finally, values of the SE escape probability and SE attenuation length are estimated for the polymers of interest and a new mechanism is suggested for the contrast reversal in scanning electron microscopy

  16. Modeling of magnetic components for power electronic converters

    Science.gov (United States)

    Hranov, Tsveti; Hinov, Nikolay

    2017-12-01

    The paper presents the modelling of magnetic components, used in the power electronic devices. Non-linear inductor and transformer are presented. During the design stage are taken into account that the converters are operated with non-sinusoidal currents and voltages. The models are realized in the MATLAB environment and their verification is done using computer simulations. The advantages of these models against the existing models are that relations between the parameters are formalized and this way the computational procedure is significantly faster. This is important in the cases when the quasi-steady-state regime in devices comes significantly slower and the investigations are requiring long simulation times.

  17. Crime Modeling using Spatial Regression Approach

    Science.gov (United States)

    Saleh Ahmar, Ansari; Adiatma; Kasim Aidid, M.

    2018-01-01

    Act of criminality in Indonesia increased both variety and quantity every year. As murder, rape, assault, vandalism, theft, fraud, fencing, and other cases that make people feel unsafe. Risk of society exposed to crime is the number of reported cases in the police institution. The higher of the number of reporter to the police institution then the number of crime in the region is increasing. In this research, modeling criminality in South Sulawesi, Indonesia with the dependent variable used is the society exposed to the risk of crime. Modelling done by area approach is the using Spatial Autoregressive (SAR) and Spatial Error Model (SEM) methods. The independent variable used is the population density, the number of poor population, GDP per capita, unemployment and the human development index (HDI). Based on the analysis using spatial regression can be shown that there are no dependencies spatial both lag or errors in South Sulawesi.

  18. A Set Theoretical Approach to Maturity Models

    DEFF Research Database (Denmark)

    Lasrado, Lester; Vatrapu, Ravi; Andersen, Kim Normann

    2016-01-01

    of it application on a social media maturity data-set. Specifically, we employ Necessary Condition Analysis (NCA) to identify maturity stage boundaries as necessary conditions and Qualitative Comparative Analysis (QCA) to arrive at multiple configurations that can be equally effective in progressing to higher......Maturity Model research in IS has been criticized for the lack of theoretical grounding, methodological rigor, empirical validations, and ignorance of multiple and non-linear paths to maturity. To address these criticisms, this paper proposes a novel set-theoretical approach to maturity models...... characterized by equifinality, multiple conjunctural causation, and case diversity. We prescribe methodological guidelines consisting of a six-step procedure to systematically apply set theoretic methods to conceptualize, develop, and empirically derive maturity models and provide a demonstration...

  19. MERGING DIGITAL SURFACE MODELS IMPLEMENTING BAYESIAN APPROACHES

    Directory of Open Access Journals (Sweden)

    H. Sadeq

    2016-06-01

    Full Text Available In this research different DSMs from different sources have been merged. The merging is based on a probabilistic model using a Bayesian Approach. The implemented data have been sourced from very high resolution satellite imagery sensors (e.g. WorldView-1 and Pleiades. It is deemed preferable to use a Bayesian Approach when the data obtained from the sensors are limited and it is difficult to obtain many measurements or it would be very costly, thus the problem of the lack of data can be solved by introducing a priori estimations of data. To infer the prior data, it is assumed that the roofs of the buildings are specified as smooth, and for that purpose local entropy has been implemented. In addition to the a priori estimations, GNSS RTK measurements have been collected in the field which are used as check points to assess the quality of the DSMs and to validate the merging result. The model has been applied in the West-End of Glasgow containing different kinds of buildings, such as flat roofed and hipped roofed buildings. Both quantitative and qualitative methods have been employed to validate the merged DSM. The validation results have shown that the model was successfully able to improve the quality of the DSMs and improving some characteristics such as the roof surfaces, which consequently led to better representations. In addition to that, the developed model has been compared with the well established Maximum Likelihood model and showed similar quantitative statistical results and better qualitative results. Although the proposed model has been applied on DSMs that were derived from satellite imagery, it can be applied to any other sourced DSMs.

  20. A Modeling Approach for Earthquake-Ionosphere Coupling

    Science.gov (United States)

    Meng, X.; Komjathy, A.; Verkhoglyadova, O. P.; Savastano, G.; Mannucci, A. J.

    2017-12-01

    We present a newly developed modeling approach for the earthquake-ionosphere coupling process, which extends the capability of Wave Perturbation - Global Ionosphere-Thermosphere Model (WP-GITM) developed originally for tsunami-ionosphere coupling. The new WP-GITM represents an earthquake as a point source at its epicenter, and takes the ground vertical velocity data from seismic measurements as input. The model then solves the neutral density, velocity, and temperature perturbations generated by spherical acoustic-gravity waves and the resulting perturbations in ions and electrons. We apply the model to simulate the near-field ionospheric disturbances during two earthquake events with different local times including the 2011 Tohoku-Oki (local afternoon) and the 2015 Illapel events (local evening). To validate the results, we retrieve receiver-to-satellite total electron content (TEC) perturbations from the simulations and compare them to the corresponding slant TEC perturbations from Global Positioning System (GPS) TEC observations. We find good agreement on magnitudes and arrival times between the simulations and observations and discuss directions of future research.

  1. Electron flux models for different energies at geostationary orbit

    Science.gov (United States)

    Boynton, R. J.; Balikhin, M. A.; Sibeck, D. G.; Walker, S. N.; Billings, S. A.; Ganushkina, N.

    2016-10-01

    Forecast models were derived for energetic electrons at all energy ranges sampled by the third-generation Geostationary Operational Environmental Satellites (GOES). These models were based on Multi-Input Single-Output Nonlinear Autoregressive Moving Average with Exogenous inputs methodologies. The model inputs include the solar wind velocity, density and pressure, the fraction of time that the interplanetary magnetic field (IMF) was southward, the IMF contribution of a solar wind-magnetosphere coupling function proposed by Boynton et al. (2011b), and the Dst index. As such, this study has deduced five new 1 h resolution models for the low-energy electrons measured by GOES (30-50 keV, 50-100 keV, 100-200 keV, 200-350 keV, and 350-600 keV) and extended the existing >800 keV and >2 MeV Geostationary Earth Orbit electron fluxes models to forecast at a 1 h resolution. All of these models were shown to provide accurate forecasts, with prediction efficiencies ranging between 66.9% and 82.3%.

  2. A semantic approach for digital long-term preservation of electronic health documents.

    Science.gov (United States)

    Kiefer, Stephan; Schäfer, Michael; Rauch, Jochen

    2012-01-01

    Long-term preservation of electronic patient health information is a key issue for life-long electronic health records, however, it is poorly implemented in healthcare institutions and little attention is given to problems like obsolescence of formats and EHR applications or changing regulations, which jeopardize reusability of information after decades of preservation. We present in this paper an ontology driven approach to digital preservation and related metadata management which seems to be superior to conventional concepts of the digital library world.

  3. Many-electron approaches in physics, chemistry and mathematics a multidisciplinary view

    CERN Document Server

    Site, Luigi

    2014-01-01

    This book provides a broad description of the development and (computational) application of many-electron approaches from a multidisciplinary perspective. In the context of studying many-electron systems Computer Science, Chemistry, Mathematics and Physics are all intimately interconnected. However, beyond a handful of communities working at the interface between these disciplines, there is still a marked separation of subjects. This book seeks to offer a common platform for possible exchanges between the various fields and to introduce the reader to perspectives for potential further developments across the disciplines. The rapid advances of modern technology will inevitably require substantial improvements in the approaches currently used, which will in turn make exchanges between disciplines indispensable. In essence this book is one of the very first attempts at an interdisciplinary approach to the many-electron problem.

  4. Band electron spectrum and thermodynamic properties of the pseudospin-electron model with tunneling splitting of levels

    Directory of Open Access Journals (Sweden)

    O.Ya.Farenyuk

    2006-01-01

    Full Text Available The pseudospin-electron model with tunneling splitting of levels is considered. Generalization of dynamic mean-field method for systems with correlated hopping was applied to the investigation of the model. Electron spectra, electron concentrations, average values of pseudospins and grand canonical potential were calculated within the alloy-analogy approximation. Electron spectrum and dependencies of the electron concentrations on chemical potential were obtained. It was shown that in the alloy-analogy approximation, the model possesses the first order phase transition to ferromagnetic state with the change of chemical potential and the second order phase transition with the change of temperature.

  5. Electrostatic models of electron-driven proton transfer across a lipid membrane

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, Anatoly Yu; Nori, Franco [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan); Mourokh, Lev G [Department of Physics, Queens College, The City University of New York, Flushing, NY 11367 (United States)

    2011-06-15

    We present two models for electron-driven uphill proton transport across lipid membranes, with the electron energy converted to the proton gradient via the electrostatic interaction. In the first model, associated with the cytochrome c oxidase complex in the inner mitochondria membranes, the electrostatic coupling to the site occupied by an electron lowers the energy level of the proton-binding site, making proton transfer possible. In the second model, roughly describing the redox loop in a nitrate respiration of E. coli bacteria, an electron displaces a proton from the negative side of the membrane to a shuttle, which subsequently diffuses across the membrane and unloads the proton to its positive side. We show that both models can be described by the same approach, which can be significantly simplified if the system is separated into several clusters, with strong Coulomb interaction inside each cluster and weak transfer couplings between them. We derive and solve the equations of motion for the electron and proton creation/annihilation operators, taking into account the appropriate Coulomb terms, tunnel couplings, and the interaction with the environment. For the second model, these equations of motion are solved jointly with a Langevin-type equation for the shuttle position. We obtain expressions for the electron and proton currents and determine their dependence on the electron and proton voltage build-ups, on-site charging energies, reorganization energies, temperature, and other system parameters. We show that the quantum yield in our models can be up to 100% and the power-conversion efficiency can reach 35%.

  6. On one peculiarity of the model describing the interaction of the electron beam with the semiconductor surface

    Science.gov (United States)

    Stepovich, M. A.; Amrastanov, A. N.; Seregina, E. V.; Filippov, M. N.

    2018-01-01

    The problem of heat distribution in semiconductor materials irradiated with sharply focused electron beams in the absence of heat exchange between the target and the external medium is considered by mathematical modeling methods. For a quantitative description of energy losses by probe electrons a model based on a separate description of the contributions of absorbed in the target and backscattered electrons and applicable to a wide class of solids and a range of primary electron energies is used. Using the features of this approach, the nonmonotonic dependence of the temperature of the maximum heating in the target on the energy of the primary electrons is explained. Some modeling results are illustrated for semiconductor materials of electronic engineering.

  7. Fusion modeling approach for novel plasma sources

    International Nuclear Information System (INIS)

    Melazzi, D; Manente, M; Pavarin, D; Cardinali, A

    2012-01-01

    The physics involved in the coupling, propagation and absorption of RF helicon waves (electronic whistler) in low temperature Helicon plasma sources is investigated by solving the 3D Maxwell-Vlasov model equations using a WKB asymptotic expansion. The reduced set of equations is formally Hamiltonian and allows for the reconstruction of the wave front of the propagating wave, monitoring along the calculation that the WKB expansion remains satisfied. This method can be fruitfully employed in a new investigation of the power deposition mechanisms involved in common Helicon low temperature plasma sources when a general confinement magnetic field configuration is allowed, unveiling new physical insight in the wave propagation and absorption phenomena and stimulating further research for the design of innovative and more efficient low temperature plasma sources. A brief overview of this methodology and its capabilities has been presented in this paper.

  8. A Modeling Approach for Marine Observatory

    Directory of Open Access Journals (Sweden)

    Charbel Geryes Aoun

    2015-02-01

    Full Text Available Infrastructure of Marine Observatory (MO is an UnderWater Sensor Networks (UW-SN to perform collaborative monitoring tasks over a given area. This observation should take into consideration the environmental constraints since it may require specific tools, materials and devices (cables, servers, etc.. The logical and physical components that are used in these observatories provide data exchanged between the various devices of the environment (Smart Sensor, Data Fusion. These components provide new functionalities or services due to the long period running of the network. In this paper, we present our approach in extending the modeling languages to include new domain- specific concepts and constraints. Thus, we propose a meta-model that is used to generate a new design tool (ArchiMO. We illustrate our proposal with an example from the MO domain on object localization with several acoustics sensors. Additionally, we generate the corresponding simulation code for a standard network simulator using our self-developed domain-specific model compiler. Our approach helps to reduce the complexity and time of the design activity of a Marine Observatory. It provides a way to share the different viewpoints of the designers in the MO domain and obtain simulation results to estimate the network capabilities.

  9. Modeling and Control of a teletruck using electronic load sensing

    DEFF Research Database (Denmark)

    Hansen, Rico Hjerm; Iversen, Asger Malte; Jensen, Mads Schmidt

    2010-01-01

    components and the potential of increased dynamic performance and efficiency, this paper investigates how HLS can be replaced with electronic control, i.e. Electronic Load Sensing (ELS). The investigation is performed by taking a specific application, a teletruck, and replace the HLS control with ELS. To aid...... the controller design for the ELS system, a complete model of the teletruck’s articulated arm and fluid power system is developed. To show the feasibility, a preliminary control structure for the ELS system is developed. The controller is tested on the machine, validating that features such as pump pressure...

  10. Transformer Model in Wide Frequency Bandwidth for Power Electronics Systems

    Directory of Open Access Journals (Sweden)

    Carlos Gonzalez-Garcia

    2013-01-01

    Full Text Available The development of the smart grids leads to new challenges on the power electronics equipment and power transformers. The use of power electronic transformer presents several advantages, but new problems related with the application of high frequency voltage and current components come across. Thus, an accurate knowledge of the transformer behavior in a wide frequency range is mandatory. A novel modeling procedure to relate the transformer physical behavior and its frequency response by means of electrical parameters is presented. Its usability is demonstrated by an example where a power transformer is used as filter and voltage reducer in an AC-DC-AC converter.

  11. ELECTRON AVALANCHE MODEL OF DIELECTRIC-VACUUM SURFACE BREAKDOWN

    Energy Technology Data Exchange (ETDEWEB)

    Lauer, E J

    2007-02-21

    The model assumes that an 'initiating event' results in positive ions on the surface near the anode and reverses the direction of the normal component of electric field so that electrons in vacuum are attracted to the dielectric locally. A sequence of surface electron avalanches progresses in steps from the anode to the cathode. For 200 kV across 1 cm, the spacing of avalanches is predicted to be about 13 microns. The time for avalanches to step from the anode to the cathode is predicted to be about a ns.

  12. Magnetic Electron Filtering by Fluid Models for the PEGASES Thruster

    Science.gov (United States)

    Leray, Gary; Chabert, Pascal; Lichtenberg, Allan; Lieberman, Michael

    2009-10-01

    The PEGASES thruster produces thrust by creating positive and negative ions, which are then accelerated. To accelerate both type of ions, electrons need to be filtered, which is achieved by applying a static magnetic field strong enough to magnetize the electrons but not the ions. A 1D fluid model with three species (electrons, positive and negative ions) and an analytical model are proposed to understand this process for an oxygen plasma with p = 10 mTorr and B0 = 300 G [1]. The resulting ion-ion plasma formation in the transverse direction (perpendicular to the magnetic field) is demonstrated. It is shown that an additional electron/positive ion loss term is required. The solutions are evaluated for two main parameters: the ionizing fraction at the plasma center (x = 0), ne0/ng, and the electronegativity ratio at the center, α0=nn0/ne0. The effect of geometry and magnetic field amplitude are also discussed. [4pt] [1] Leray G, Chabert P, Lichtenberg A J and Lieberman M A, J. Phys. D: Appl. Phys., Plasma Modelling Cluster issue, to appear (2009)

  13. A nationwide modelling approach to decommissioning - 16182

    International Nuclear Information System (INIS)

    Kelly, Bernard; Lowe, Andy; Mort, Paul

    2009-01-01

    In this paper we describe a proposed UK national approach to modelling decommissioning. For the first time, we shall have an insight into optimizing the safety and efficiency of a national decommissioning strategy. To do this we use the General Case Integrated Waste Algorithm (GIA), a universal model of decommissioning nuclear plant, power plant, waste arisings and the associated knowledge capture. The model scales from individual items of plant through cells, groups of cells, buildings, whole sites and then on up to a national scale. We describe the national vision for GIA which can be broken down into three levels: 1) the capture of the chronological order of activities that an experienced decommissioner would use to decommission any nuclear facility anywhere in the world - this is Level 1 of GIA; 2) the construction of an Operational Research (OR) model based on Level 1 to allow rapid what if scenarios to be tested quickly (Level 2); 3) the construction of a state of the art knowledge capture capability that allows future generations to learn from our current decommissioning experience (Level 3). We show the progress to date in developing GIA in levels 1 and 2. As part of level 1, GIA has assisted in the development of an IMechE professional decommissioning qualification. Furthermore, we describe GIA as the basis of a UK-Owned database of decommissioning norms for such things as costs, productivity, durations etc. From level 2, we report on a pilot study that has successfully tested the basic principles for the OR numerical simulation of the algorithm. We then highlight the advantages of applying the OR modelling approach nationally. In essence, a series of 'what if...' scenarios can be tested that will improve the safety and efficiency of decommissioning. (authors)

  14. A multiscale approach for modeling atherosclerosis progression.

    Science.gov (United States)

    Exarchos, Konstantinos P; Carpegianni, Clara; Rigas, Georgios; Exarchos, Themis P; Vozzi, Federico; Sakellarios, Antonis; Marraccini, Paolo; Naka, Katerina; Michalis, Lambros; Parodi, Oberdan; Fotiadis, Dimitrios I

    2015-03-01

    Progression of atherosclerotic process constitutes a serious and quite common condition due to accumulation of fatty materials in the arterial wall, consequently posing serious cardiovascular complications. In this paper, we assemble and analyze a multitude of heterogeneous data in order to model the progression of atherosclerosis (ATS) in coronary vessels. The patient's medical record, biochemical analytes, monocyte information, adhesion molecules, and therapy-related data comprise the input for the subsequent analysis. As indicator of coronary lesion progression, two consecutive coronary computed tomography angiographies have been evaluated in the same patient. To this end, a set of 39 patients is studied using a twofold approach, namely, baseline analysis and temporal analysis. The former approach employs baseline information in order to predict the future state of the patient (in terms of progression of ATS). The latter is based on an approach encompassing dynamic Bayesian networks whereby snapshots of the patient's status over the follow-up are analyzed in order to model the evolvement of ATS, taking into account the temporal dimension of the disease. The quantitative assessment of our work has resulted in 93.3% accuracy for the case of baseline analysis, and 83% overall accuracy for the temporal analysis, in terms of modeling and predicting the evolvement of ATS. It should be noted that the application of the SMOTE algorithm for handling class imbalance and the subsequent evaluation procedure might have introduced an overestimation of the performance metrics, due to the employment of synthesized instances. The most prominent features found to play a substantial role in the progression of the disease are: diabetes, cholesterol and cholesterol/HDL. Among novel markers, the CD11b marker of leukocyte integrin complex is associated with coronary plaque progression.

  15. A new approach to front-end electronics interfacing in the ATLAS experiment

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00015561; Borga, Andrea; Boterenbrood, Hendrik; Chen, Hucheng; Chen, Kai; Drake, Gary; Donszelmann, Mark; Francis, David; Gorini, Benedetto; Lanni, Francesco; Lehmann Miotto, Giovanna; Levinson, Lorne; Narevicius, Julia; Roich, Alexander; Ryu, Soo; Schreuder, Frans Philip; Schumacher, Jorn; Vandelli, Wainer; Vermeulen, Jos; Wu, Weihao; Zhang, Jinlong

    2016-01-01

    For new detector and trigger systems to be installed in the ATLAS experiment after LHC Run 2, a new approach will be followed for Front-End electronics interfacing. The FELIX (Front-End LInk eXchange) system will function as gateway connecting: on one side to detector and trigger electronics links, as well as providing timing and trigger (TTC) information; and on the other side a commodity switched network built using standard technology (either Ethernet or Infiniband). The new approach is described in this paper, and results achieved so far are presented.

  16. A new approach to front-­‐end electronics interfacing in the ATLAS experiment

    CERN Document Server

    Borga, Andrea; The ATLAS collaboration; Lanni, Francesco; Lehmann Miotto, Giovanna; Levinson, Lorne; Narevicius, Julia; Roich, Alexander; Schreuder, Frans Philip; Schumacher, J\\"orn; Vandelli, Wainer; Vermeulen, Jos; Ryu, Soo; Zhang, Jinlong; Anderson, John Thomas; Boterenbrood, Hendrik; Chen, Kai; Chen, Hucheng; Drake, Gary; Donszelmann, Mark; Francis, David

    2015-01-01

    For new detector and trigger systems to be installed in the ATLAS experiment after LHC Run 2 a new approach will be followed for front-end electronics interfacing. The FELIX (Front-End Link eXchange) system will interface to links connecting to front-end detector and trigger electronics instead of the RODs (ReadOut Drivers) currently used. FELIX will function as a gateway to a commodity switched network built using standard technology (either Ethernet or Infiniband). In the paper the new approach will be described and results of the demonstrator program currently in progress will be presented.

  17. The Development Model Electronic Commerce of Regional Agriculture

    Science.gov (United States)

    Kang, Jun; Cai, Lecai; Li, Hongchan

    With the developing of the agricultural information, it is inevitable trend of the development of agricultural electronic commercial affairs. On the basis of existing study on the development application model of e-commerce, combined with the character of the agricultural information, compared with the developing model from the theory and reality, a new development model electronic commerce of regional agriculture base on the government is put up, and such key issues as problems of the security applications, payment mode, sharing mechanisms, and legal protection are analyzed, etc. The among coordination mechanism of the region is discussed on, it is significance for regulating the development of agricultural e-commerce and promoting the regional economical development.

  18. Modeling in transport phenomena a conceptual approach

    CERN Document Server

    Tosun, Ismail

    2007-01-01

    Modeling in Transport Phenomena, Second Edition presents and clearly explains with example problems the basic concepts and their applications to fluid flow, heat transfer, mass transfer, chemical reaction engineering and thermodynamics. A balanced approach is presented between analysis and synthesis, students will understand how to use the solution in engineering analysis. Systematic derivations of the equations and the physical significance of each term are given in detail, for students to easily understand and follow up the material. There is a strong incentive in science and engineering to

  19. Model approach brings multi-level success.

    Science.gov (United States)

    Howell, Mark

    2012-08-01

    n an article that first appeared in US magazine, Medical Construction & Design, Mark Howell, senior vice-president of Skanska USA Building, based in Seattle, describes the design and construction of a new nine-storey, 350,000 ft2 extension to the Good Samaritan Hospital in Puyallup, Washington state. He explains how the use of an Integrated Project Delivery (IPD) approach by the key players, and extensive use of building information modelling (BIM), combined to deliver a healthcare facility that he believes should meet the needs of patients, families, and the clinical care team, 'well into the future'.

  20. Relativistic phase effect in modeling interactions between ultraintense laser beams and electrons plasma

    Science.gov (United States)

    Popa, Alexandru; Stancalie, Viorica

    2017-06-01

    In a series of previous papers we proved an accurate connection between quantum and classical equations in the case of electrodynamic systems. We have used this connection to elaborate simplified models for systems composed of very intense laser beams and electrons or atoms. These models are in good agreement with numerous experimental data from literature. In this paper we develop the above approach for the new field of interactions between ultraintense laser beams, having intensities in the range 1018 - 1022 W/cm2, and electron plasmas. We show that in this case new effects take place, such as the fact that the variation of the phase of the field at the point where the electron is situated, decreases when the intensity of the field increases, due to a strong relativistic behavior. This effect leads to an aperiodic behavior of the radiations generated by above interactions, and to a possible new method for solitary waves generation.

  1. Modeling power electronics and interfacing energy conversion systems

    CERN Document Server

    Simões, Marcelo Godoy

    2017-01-01

    Discusses the application of mathematical and engineering tools for modeling, simulation and control oriented for energy systems, power electronics and renewable energy. This book builds on the background knowledge of electrical circuits, control of dc/dc converters and inverters, energy conversion and power electronics. The book shows readers how to apply computational methods for multi-domain simulation of energy systems and power electronics engineering problems. Each chapter has a brief introduction on the theoretical background, a description of the problems to be solved, and objectives to be achieved. Block diagrams, electrical circuits, mathematical analysis or computer code are covered. Each chapter concludes with discussions on what should be learned, suggestions for further studies and even some experimental work.

  2. Global GPS Ionospheric Modelling Using Spherical Harmonic Expansion Approach

    Directory of Open Access Journals (Sweden)

    Byung-Kyu Choi

    2010-12-01

    Full Text Available In this study, we developed a global ionosphere model based on measurements from a worldwide network of global positioning system (GPS. The total number of the international GPS reference stations for development of ionospheric model is about 100 and the spherical harmonic expansion approach as a mathematical method was used. In order to produce the ionospheric total electron content (TEC based on grid form, we defined spatial resolution of 2.0 degree and 5.0 degree in latitude and longitude, respectively. Two-dimensional TEC maps were constructed within the interval of one hour, and have a high temporal resolution compared to global ionosphere maps which are produced by several analysis centers. As a result, we could detect the sudden increase of TEC by processing GPS observables on 29 October, 2003 when the massive solar flare took place.

  3. An object-oriented approach for structuring the electronic medical record.

    Science.gov (United States)

    Banhart, F; Lohmann, R

    2000-01-01

    We implemented a framework for modelling the electronic medical record on top of an object-oriented model. Clinical patient data are structured in a uniform way through the use of a comprehensive data model. The meaning of the information elements is explicitly determined by a medical data dictionary. The data structures of both, medical record and data dictionary are implemented, using a semantically rich, object-oriented data model. We examined several possibilities for the graphical preparation of the inherently recursive data structures. Again, we use object-oriented frameworks for the implementation of flexible user interfaces to the electronic medical record with a consistent look-and-feel.

  4. Pedagogic process modeling: Humanistic-integrative approach

    Directory of Open Access Journals (Sweden)

    Boritko Nikolaj M.

    2007-01-01

    Full Text Available The paper deals with some current problems of modeling the dynamics of the subject-features development of the individual. The term "process" is considered in the context of the humanistic-integrative approach, in which the principles of self education are regarded as criteria for efficient pedagogic activity. Four basic characteristics of the pedagogic process are pointed out: intentionality reflects logicality and regularity of the development of the process; discreteness (stageability in dicates qualitative stages through which the pedagogic phenomenon passes; nonlinearity explains the crisis character of pedagogic processes and reveals inner factors of self-development; situationality requires a selection of pedagogic conditions in accordance with the inner factors, which would enable steering the pedagogic process. Offered are two steps for singling out a particular stage and the algorithm for developing an integrative model for it. The suggested conclusions might be of use for further theoretic research, analyses of educational practices and for realistic predicting of pedagogical phenomena. .

  5. High throughput ab initio modeling of charge transport for bio-molecular-electronics

    Science.gov (United States)

    Bruque, Nicolas Alexander

    2009-12-01

    Self-assembled nanostructures, composed of inorganic and organic materials, have multiple applications in the fields of engineering and nanotechnology. Experimental research using nanoscaled materials, such as semiconductor/metallic nanocrystals, nanowires (NW), and carbon nanotube (CNT)-molecular systems have potential applications in next generation nano electronic devices. Many of these molecular systems exhibit electronic device functionality. However, experimental analytical techniques to determine how the chemistry and geometry affects electron transport through these devices does not yet exist. Using theory and modeling, one can approximate the chemistry and geometry at the atomic level and also determine how the chemistry and geometry governs electron current. Nanoelectronic devices however, contain several thousand atoms which makes quantum modeling difficult. Popular atomistic modeling approaches are capable of handling small molecular systems, which are of scientific interest, but have little engineering value. The lack of large scale modeling tools has left the scientific and engineering community with a limited ability to understand, explore, and design complex systems of engineering interest. To address these issues, I have developed a high performance general quantum charge transport model based on the non-equilibrium Green function (NEGF) formalism using density functional theory (DFT) as implemented in the FIREBALL software. FIREBALL is a quantum molecular dynamics code which has demonstrated the ability to model large molecular systems. This dissertation project of integrating NEGF into FIREBALL provides researchers with a modeling tool capable of simulating charge current in large inorganic/organic systems. To provide theoretical support for experimental efforts, this project focused on CNT-molecular systems, which includes the discovery of a CNT-molecular resonant tunneling diode (RTD) for electronic circuit applications. This research also

  6. Atomic modeling of cryo-electron microscopy reconstructions--joint refinement of model and imaging parameters.

    Science.gov (United States)

    Chapman, Michael S; Trzynka, Andrew; Chapman, Brynmor K

    2013-04-01

    When refining the fit of component atomic structures into electron microscopic reconstructions, use of a resolution-dependent atomic density function makes it possible to jointly optimize the atomic model and imaging parameters of the microscope. Atomic density is calculated by one-dimensional Fourier transform of atomic form factors convoluted with a microscope envelope correction and a low-pass filter, allowing refinement of imaging parameters such as resolution, by optimizing the agreement of calculated and experimental maps. A similar approach allows refinement of atomic displacement parameters, providing indications of molecular flexibility even at low resolution. A modest improvement in atomic coordinates is possible following optimization of these additional parameters. Methods have been implemented in a Python program that can be used in stand-alone mode for rigid-group refinement, or embedded in other optimizers for flexible refinement with stereochemical restraints. The approach is demonstrated with refinements of virus and chaperonin structures at resolutions of 9 through 4.5 Å, representing regimes where rigid-group and fully flexible parameterizations are appropriate. Through comparisons to known crystal structures, flexible fitting by RSRef is shown to be an improvement relative to other methods and to generate models with all-atom rms accuracies of 1.5-2.5 Å at resolutions of 4.5-6 Å. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. An integrated approach to the modelling of hydrogen assisted failure in 316L steel

    International Nuclear Information System (INIS)

    Toribio, J.; Justo, E.R.; Caballero, L.; Valiente, A.

    1998-01-01

    An integrated approach to the modelling of hydrogen assisted failure in 316L steel is presented. The approach includes experimental, fractographic, numerical and theoretical analysis of the phenomenon. The physical adequacy of the mechanical models of hydrogen embrittlement (notch extension model and notch cracking model) is discussed by comparing the virtual damage depth (theoretical) predicted by the models with the embrittled zone (microphysical) measured in the fractographic analysis by scanning electron microscopy. In addition, a numerical modelling of hydrogen diffusion is performed, concluding that bulk diffusion is not important in hydrogen embrittlement of 316L steel, so that hydrogen transport accelerated by the microdamage itself should be taken into account. (orig.)

  8. An analytical approach to characterize morbidity profile dissimilarity between distinct cohorts using electronic medical records

    OpenAIRE

    Schildcrout, Jonathan S.; Basford, Melissa A.; Pulley, Jill M.; Masys, Daniel R.; Roden, Dan M.; Wang, Deede; Chute, Christopher G.; Kullo, Iftikhar J.; Carrell, David; Peissig, Peggy; Kho, Abel; Denny, Joshua C.

    2010-01-01

    We describe a two-stage analytical approach for characterizing morbidity profile dissimilarity among patient cohorts using electronic medical records. We capture morbidities using the International Statistical Classification of Diseases and Related Health Problems (ICD-9) codes. In the first stage of the approach separate logistic regression analyses for ICD-9 sections (e.g., “hypertensive disease” or “appendicitis”) are conducted, and the odds ratios that describe adjusted differences in pre...

  9. Quantum Geometry: Relativistic energy approach to cooperative electron-nucleary-transition spectrum

    Directory of Open Access Journals (Sweden)

    Ольга Юрьевна Хецелиус

    2014-11-01

    Full Text Available An advanced relativistic energy approach is presented and applied to calculating parameters of electron-nuclear 7-transition spectra of nucleus in the atom. The intensities of the spectral satellites are defined in the relativistic version of the energy approach (S-matrix formalism, and gauge-invariant quantum-electrodynamical perturbation theory with the Dirac-Kohn-Sham density-functional zeroth approximation.

  10. Modeling and multidimensional optimization of a tapered free electron laser

    Directory of Open Access Journals (Sweden)

    Y. Jiao

    2012-05-01

    Full Text Available Energy extraction efficiency of a free electron laser (FEL can be greatly increased using a tapered undulator and self-seeding. However, the extraction rate is limited by various effects that eventually lead to saturation of the peak intensity and power. To better understand these effects, we develop a model extending the Kroll-Morton-Rosenbluth, one-dimensional theory to include the physics of diffraction, optical guiding, and radially resolved particle trapping. The predictions of the model agree well with that of the GENESIS single-frequency numerical simulations. In particular, we discuss the evolution of the electron-radiation interaction along the tapered undulator and show that the decreasing of refractive guiding is the major cause of the efficiency reduction, particle detrapping, and then saturation of the radiation power. With this understanding, we develop a multidimensional optimization scheme based on GENESIS simulations to increase the energy extraction efficiency via an improved taper profile and variation in electron beam radius. We present optimization results for hard x-ray tapered FELs, and the dependence of the maximum extractable radiation power on various parameters of the initial electron beam, radiation field, and the undulator system. We also study the effect of the sideband growth in a tapered FEL. Such growth induces increased particle detrapping and thus decreased refractive guiding that together strongly limit the overall energy extraction efficiency.

  11. Advanced electron crystallography through model-based imaging

    Science.gov (United States)

    Van Aert, Sandra; De Backer, Annick; Martinez, Gerardo T.; den Dekker, Arnold J.; Van Dyck, Dirk; Bals, Sara; Van Tendeloo, Gustaaf

    2016-01-01

    The increasing need for precise determination of the atomic arrangement of non-periodic structures in materials design and the control of nanostructures explains the growing interest in quantitative transmission electron microscopy. The aim is to extract precise and accurate numbers for unknown structure parameters including atomic positions, chemical concentrations and atomic numbers. For this purpose, statistical parameter estimation theory has been shown to provide reliable results. In this theory, observations are considered purely as data planes, from which structure parameters have to be determined using a parametric model describing the images. As such, the positions of atom columns can be measured with a precision of the order of a few picometres, even though the resolution of the electron microscope is still one or two orders of magnitude larger. Moreover, small differences in average atomic number, which cannot be distinguished visually, can be quantified using high-angle annular dark-field scanning transmission electron microscopy images. In addition, this theory allows one to measure compositional changes at interfaces, to count atoms with single-atom sensitivity, and to reconstruct atomic structures in three dimensions. This feature article brings the reader up to date, summarizing the underlying theory and highlighting some of the recent applications of quantitative model-based transmisson electron microscopy. PMID:26870383

  12. Advanced electron crystallography through model-based imaging

    Directory of Open Access Journals (Sweden)

    Sandra Van Aert

    2016-01-01

    Full Text Available The increasing need for precise determination of the atomic arrangement of non-periodic structures in materials design and the control of nanostructures explains the growing interest in quantitative transmission electron microscopy. The aim is to extract precise and accurate numbers for unknown structure parameters including atomic positions, chemical concentrations and atomic numbers. For this purpose, statistical parameter estimation theory has been shown to provide reliable results. In this theory, observations are considered purely as data planes, from which structure parameters have to be determined using a parametric model describing the images. As such, the positions of atom columns can be measured with a precision of the order of a few picometres, even though the resolution of the electron microscope is still one or two orders of magnitude larger. Moreover, small differences in average atomic number, which cannot be distinguished visually, can be quantified using high-angle annular dark-field scanning transmission electron microscopy images. In addition, this theory allows one to measure compositional changes at interfaces, to count atoms with single-atom sensitivity, and to reconstruct atomic structures in three dimensions. This feature article brings the reader up to date, summarizing the underlying theory and highlighting some of the recent applications of quantitative model-based transmisson electron microscopy.

  13. Electronic Model of a Ferroelectric Field Effect Transistor

    Science.gov (United States)

    MacLeod, Todd C.; Ho, Fat Duen; Russell, Larry (Technical Monitor)

    2001-01-01

    A pair of electronic models has been developed of a Ferroelectric Field Effect transistor. These models can be used in standard electrical circuit simulation programs to simulate the main characteristics of the FFET. The models use the Schmitt trigger circuit as a basis for their design. One model uses bipolar junction transistors and one uses MOSFET's. Each model has the main characteristics of the FFET, which are the current hysterisis with different gate voltages and decay of the drain current when the gate voltage is off. The drain current from each model has similar values to an actual FFET that was measured experimentally. T'he input and o Output resistance in the models are also similar to that of the FFET. The models are valid for all frequencies below RF levels. No attempt was made to model the high frequency characteristics of the FFET. Each model can be used to design circuits using FFET's with standard electrical simulation packages. These circuits can be used in designing non-volatile memory circuits and logic circuits and is compatible with all SPICE based circuit analysis programs. The models consist of only standard electrical components, such as BJT's, MOSFET's, diodes, resistors, and capacitors. Each model is compared to the experimental data measured from an actual FFET.

  14. Angular sensitivity of modeled scientific silicon charge-coupled devices to initial electron direction

    Energy Technology Data Exchange (ETDEWEB)

    Plimley, Brian, E-mail: brian.plimley@gmail.com [Nuclear Engineering Department, University of California, Berkeley, CA (United States); Coffer, Amy; Zhang, Yigong [Nuclear Engineering Department, University of California, Berkeley, CA (United States); Vetter, Kai [Nuclear Engineering Department, University of California, Berkeley, CA (United States); Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States)

    2016-08-11

    Previously, scientific silicon charge-coupled devices (CCDs) with 10.5-μm pixel pitch and a thick (650 μm), fully depleted bulk have been used to measure gamma-ray-induced fast electrons and demonstrate electron track Compton imaging. A model of the response of this CCD was also developed and benchmarked to experiment using Monte Carlo electron tracks. We now examine the trade-off in pixel pitch and electronic noise. We extend our CCD response model to different pixel pitch and readout noise per pixel, including pixel pitch of 2.5 μm, 5 μm, 10.5 μm, 20 μm, and 40 μm, and readout noise from 0 eV/pixel to 2 keV/pixel for 10.5 μm pixel pitch. The CCD images generated by this model using simulated electron tracks are processed by our trajectory reconstruction algorithm. The performance of the reconstruction algorithm defines the expected angular sensitivity as a function of electron energy, CCD pixel pitch, and readout noise per pixel. Results show that our existing pixel pitch of 10.5 μm is near optimal for our approach, because smaller pixels add little new information but are subject to greater statistical noise. In addition, we measured the readout noise per pixel for two different device temperatures in order to estimate the effect of temperature on the reconstruction algorithm performance, although the readout is not optimized for higher temperatures. The noise in our device at 240 K increases the FWHM of angular measurement error by no more than a factor of 2, from 26° to 49° FWHM for electrons between 425 keV and 480 keV. Therefore, a CCD could be used for electron-track-based imaging in a Peltier-cooled device.

  15. Analytical thermal modelling of multilayered active embedded chips into high density electronic board

    Directory of Open Access Journals (Sweden)

    Monier-Vinard Eric

    2013-01-01

    Full Text Available The recent Printed Wiring Board embedding technology is an attractive packaging alternative that allows a very high degree of miniaturization by stacking multiple layers of embedded chips. This disruptive technology will further increase the thermal management challenges by concentrating heat dissipation at the heart of the organic substrate structure. In order to allow the electronic designer to early analyze the limits of the power dissipation, depending on the embedded chip location inside the board, as well as the thermal interactions with other buried chips or surface mounted electronic components, an analytical thermal modelling approach was established. The presented work describes the comparison of the analytical model results with the numerical models of various embedded chips configurations. The thermal behaviour predictions of the analytical model, found to be within ±10% of relative error, demonstrate its relevance for modelling high density electronic board. Besides the approach promotes a practical solution to study the potential gain to conduct a part of heat flow from the components towards a set of localized cooled board pads.

  16. A doping-free approach to carbon nanotube electronics and optoelectronics

    Directory of Open Access Journals (Sweden)

    Lian-Mao Peng

    2012-12-01

    Full Text Available The electronic properties of conventional semiconductor are usually controlled by doping, which introduces carriers into the semiconductor but also distortion and scattering centers to the otherwise perfect lattice, leading to increased scattering and power consumption that becomes the limiting factors for the ultimate performance of the next generation electronic devices. Among new materials that have been considered as potential replacing channel materials for silicon, carbon nanotubes (CNTs have been extensively studied and shown to have all the remarkable electronic properties that an ideal electronic material should have, but controlled doping in CNTs has been proved to be challenging. In this article we will review a doping-free approach for constructing nanoelectronic and optoelectronic devices and integrated circuits. This technique relies on a unique property of CNTs, i.e. high quality ohmic contacts can be made to both the conduction band and valence band of a semiconducting CNT. High performance nanoelectronic and optoelectronic devices have been fabricated using CNTs with this method and performance approach to that of quantum limit. In principle high performance electronic devices and optoelectronic devices can be integrated on the same carbon nanotube with the same footing, and this opens new possibilities for electronics beyond the Moore law in the future.

  17. Systematic approach to verification and validation: High explosive burn models

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph [Los Alamos National Laboratory; Scovel, Christina A. [Los Alamos National Laboratory

    2012-04-16

    Most material models used in numerical simulations are based on heuristics and empirically calibrated to experimental data. For a specific model, key questions are determining its domain of applicability and assessing its relative merits compared to other models. Answering these questions should be a part of model verification and validation (V and V). Here, we focus on V and V of high explosive models. Typically, model developers implemented their model in their own hydro code and use different sets of experiments to calibrate model parameters. Rarely can one find in the literature simulation results for different models of the same experiment. Consequently, it is difficult to assess objectively the relative merits of different models. This situation results in part from the fact that experimental data is scattered through the literature (articles in journals and conference proceedings) and that the printed literature does not allow the reader to obtain data from a figure in electronic form needed to make detailed comparisons among experiments and simulations. In addition, it is very time consuming to set up and run simulations to compare different models over sufficiently many experiments to cover the range of phenomena of interest. The first difficulty could be overcome if the research community were to support an online web based database. The second difficulty can be greatly reduced by automating procedures to set up and run simulations of similar types of experiments. Moreover, automated testing would be greatly facilitated if the data files obtained from a database were in a standard format that contained key experimental parameters as meta-data in a header to the data file. To illustrate our approach to V and V, we have developed a high explosive database (HED) at LANL. It now contains a large number of shock initiation experiments. Utilizing the header information in a data file from HED, we have written scripts to generate an input file for a hydro code

  18. A modified linear algebraic approach to electron scattering using cubic splines

    International Nuclear Information System (INIS)

    Kinney, R.A.

    1986-01-01

    A modified linear algebraic approach to the solution of the Schrodiner equation for low-energy electron scattering is presented. The method uses a piecewise cubic-spline approximation of the wavefunction. Results in the static-potential and the static-exchange approximations for e - +H s-wave scattering are compared with unmodified linear algebraic and variational linear algebraic methods. (author)

  19. Electronic properties of GaV4S8: A percolation approach

    Indian Academy of Sciences (India)

    Electronic properties of GaV4S8: A percolation approach. I NAIK1,∗, S HANSDA1 and A K RASTOGI2. 1Department of Physics, North Orissa University, Baripada 757 003, India. 2School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110 067, India. ∗. Corresponding author. E-mail: indrajit_naik@yahoo.co.

  20. Hot electrons and the approach to metallic behavior in Kx(KCl)1-x

    NARCIS (Netherlands)

    Silvestrelli, P.L.; Alavi, A.; Parrinello, M.; Frenkel, D.

    1996-01-01

    The approach to the metallic phase of molten Kx(KCl)1-x mixtures is studied using ab initio molecular dynamics based on finite-temperature density functional theory. The finite electronic temperature is found to result in new and unexpected effects. In particular, we observe a thermally induced

  1. MediaEval 2014: A Multimodal Approach to Drop Detection in Electronic Dance Music

    NARCIS (Netherlands)

    Aljanaki, Anna; Soleymani, Mohammad; Wiering, Frans; Veltkamp, Remco

    2014-01-01

    We predict drops in electronic dance music (EDM), employing different multimodal approaches. We combine three sources of data: noisy labels collected through crowdsourcing, timed comments from SoundCloud and audio content analysis. We predict the correct labels from the noisy labels using the

  2. Quantum entanglement in two-electron atomic models

    Energy Technology Data Exchange (ETDEWEB)

    Manzano, D; Plastino, A R; Dehesa, J S [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, Granada E-18071 (Spain); Koga, T, E-mail: arplastino@ugr.e [Applied Chemistry Research Unit, Graduate School of Engineering, Muroran Institute of Technology, Muroran, Hokkaido 050-8585 (Japan)

    2010-07-09

    We explore the main entanglement properties exhibited by the eigenfunctions of two exactly soluble two-electron models, the Crandall atom and the Hooke atom, and compare them with the entanglement features of helium-like systems. We compute the amount of entanglement associated with the wavefunctions corresponding to the fundamental and first few excited states of these models. We investigate the dependence of the entanglement on the parameters of the models and on the quantum numbers of the eigenstates. It is found that the amount of entanglement of the system tends to increase with energy in both models. In addition, we study the entanglement of a few states of helium-like systems, which we compute using high-quality Kinoshita-like eigenfunctions. The dependence of the entanglement of helium-like atoms on the nuclear charge and on energy is found to be consistent with the trends observed in the previous two model systems.

  3. Use of mathematical modelling in electron beam processing: A guidebook

    International Nuclear Information System (INIS)

    2010-01-01

    The use of electron beam irradiation for industrial applications, like the sterilization of medical devices or cross-linking of polymers, has a long and successful track record and has proven itself to be a key technology. Emerging fields, including environmental applications of ionizing radiation, the sterilization of complex medical and pharmaceutical products or advanced material treatment, require the design and control of even more complex irradiators and irradiation processes. Mathematical models can aid the design process, for example by calculating absorbed dose distributions in a product, long before any prototype is built. They support process qualification through impact assessment of process variable uncertainties, and can be an indispensable teaching tool for technologists in training in the use of radiation processing. The IAEA, through various mechanisms, including its technical cooperation programme, coordinated research projects, technical meetings, guidelines and training materials, is promoting the use of radiation technologies to minimize the effects of harmful contaminants and develop value added products originating from low cost natural and human made raw materials. The need to publish a guidebook on the use of mathematical modelling for design processes in the electron beam treatment of materials was identified through the increased interest of radiation processing laboratories in Member States and as a result of recommendations from several IAEA expert meetings. In response, the IAEA has prepared this report using the services of an expert in the field. This publication should serve as both a guidebook and introductory tutorial for the use of mathematical modelling (using mostly Monte Carlo methods) in electron beam processing. The emphasis of this guide is on industrial irradiation methodologies with a strong reference to existing literature and applicable standards. Its target audience is readers who have a basic understanding of electron

  4. Transverse Momentum Distributions of Electron in Simulated QED Model

    Science.gov (United States)

    Kaur, Navdeep; Dahiya, Harleen

    2018-05-01

    In the present work, we have studied the transverse momentum distributions (TMDs) for the electron in simulated QED model. We have used the overlap representation of light-front wave functions where the spin-1/2 relativistic composite system consists of spin-1/2 fermion and spin-1 vector boson. The results have been obtained for T-even TMDs in transverse momentum plane for fixed value of longitudinal momentum fraction x.

  5. Electron microscopy approach for the visualization of the epithelial and endothelial glycocalyx.

    Science.gov (United States)

    Chevalier, L; Selim, J; Genty, D; Baste, J M; Piton, N; Boukhalfa, I; Hamzaoui, M; Pareige, P; Richard, V

    2017-06-01

    This study presents a methodological approach for the visualization of the glycocalyx by electron microscopy. The glycocalyx is a three dimensional network mainly composed of glycolipids, glycoproteins and proteoglycans associated with the plasma membrane. Since less than a decade, the epithelial and endothelial glycocalyx proved to play an important role in physiology and pathology, increasing its research interest especially in vascular functions. Therefore, visualization of the glycocalyx requires reliable techniques and its preservation remains challenging due to its fragile and dynamic organization, which is highly sensitive to the different process steps for electron microscopy sampling. In this study, chemical fixation was performed by perfusion as a good alternative to conventional fixation. Additional lanthanum nitrate in the fixative enhances staining of the glycocalyx in transmission electron microscopy bright field and improves its visualization by detecting the elastic scattered electrons, thus providing a chemical contrast. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  6. A new approach to modeling aviation accidents

    Science.gov (United States)

    Rao, Arjun Harsha

    views aviation accidents as a set of hazardous states of a system (pilot and aircraft), and triggers that cause the system to move between hazardous states. I used the NTSB's accident coding manual (that contains nearly 4000 different codes) to develop a "dictionary" of hazardous states, triggers, and information codes. Then, I created the "grammar", or a set of rules, that: (1) orders the hazardous states in each accident; and, (2) links the hazardous states using the appropriate triggers. This approach: (1) provides a more correct count of the causes for accidents in the NTSB database; and, (2) checks for gaps or omissions in NTSB accident data, and fills in some of these gaps using logic-based rules. These rules also help identify and count causes for accidents that were not discernable from previous analyses of historical accident data. I apply the model to 6200 helicopter accidents that occurred in the US between 1982 and 2015. First, I identify the states and triggers that are most likely to be associated with fatal and non-fatal accidents. The results suggest that non-fatal accidents, which account for approximately 84% of the accidents, provide valuable opportunities to learn about the causes for accidents. Next, I investigate the causes of inflight loss of control using both a conventional approach and using the state-based approach. The conventional analysis provides little insight into the causal mechanism for LOC. For instance, the top cause of LOC is "aircraft control/directional control not maintained", which does not provide any insight. In contrast, the state-based analysis showed that pilots' tendency to clip objects frequently triggered LOC (16.7% of LOC accidents)--this finding was not directly discernable from conventional analyses. Finally, I investigate the causes for improper autorotations using both a conventional approach and the state-based approach. The conventional approach uses modifiers (e.g., "improper", "misjudged") associated with "24520

  7. A new electron density model of the plasmasphere for operational applications and services

    Science.gov (United States)

    Jakowski, Norbert; Hoque, Mohammed Mainul

    2018-03-01

    The Earth's plasmasphere contributes essentially to total electron content (TEC) measurements from ground or satellite platforms. Furthermore, as an integral part of space weather, associated plasmaspheric phenomena must be addressed in conjunction with ionosphere weather monitoring by operational space weather services. For supporting space weather services and mitigation of propagation errors in Global Navigation Satellite Systems (GNSS) applications we have developed the empirical Neustrelitz plasmasphere model (NPSM). The model consists of an upper L shell dependent part and a lower altitude dependent part, both described by specific exponential decays. Here the McIllwain parameter L defines the geomagnetic field lines in a centered dipole model for the geomagnetic field. The coefficients of the developed approaches are successfully fitted to numerous electron density data derived from dual frequency GPS measurements on-board the CHAMP satellite mission from 2000 to 2005. The data are utilized for fitting up to the L shell L = 3 because a previous validation has shown a good agreement with IMAGE/RPI measurements up to this value. Using the solar radio flux index F10.7 as the only external parameter, the operation of the model is robust, with 40 coefficients fast and sufficiently accurate to be used as a background model for estimating TEC or electron density profiles in near real time GNSS applications and services. In addition to this, the model approach is sensitive to ionospheric coupling resulting in anomalies such as the Nighttime Winter Anomaly and the related Mid-Summer Nighttime Anomaly and even shows a slight plasmasphere compression of the dayside plasmasphere due to solar wind pressure. Modelled electron density and TEC values agree with estimates reported in the literature in similar cases.

  8. Modeling Earth's Outer Radiation Belt Electron Dynamics---Radial Diffusion, Heating, and Loss

    Science.gov (United States)

    Tu, Weichao

    belt electrons at low altitudes demonstrate that the adiabatic flux drop of electrons during the storm main phase is both altitude and storm dependent. During the main phase of a moderate geomagnetic storm, due solely to adiabatic effects a satellite at low altitude sees either zero electron flux or a fractional flux drop depending on its altitude. To physically quantify the radial diffusion rate, we use power spectral density and global mode structure of the Ultra-Low-Frequency (ULF) waves, which are derived from the Lyon-Fedder-Mobarry (LFM) MHD simulation and validated by field data from real satellites. The calculated total diffusion rate is shown to be dominated by the contribution from magnetic field perturbations, and much less from the electric field. Fast diffusion generally occurs when solar wind dynamic pressure is high or nightside geomagnetic activity is strong and with higher diffusion rates at higher L regions. Work performed in this thesis provides realistic loss rate and radial diffusion rate of radiation belt electrons, as well as a comprehensive Fokker-Planck model that can take the loss and radial diffusion rates as inputs and then determine the internal heating rate with less uncertainty. By this approach, we will be able to quantitatively understand the relative contribution of radial diffusion, wave heating, and loss to the variations of radiation belt electrons.

  9. Modeling of the atomic and electronic structures of interfaces

    International Nuclear Information System (INIS)

    Sutton, A.P.

    1988-01-01

    Recent tight binding and Car-Parrinello simulations of grain boundaries in semiconductors are reviewed. A critique is given of some models of embrittlement that are based on electronic structure considerations. The structural unit model of grain boundary structure is critically assessed using some results for mixed tilt and twist grain boundaries. A new method of characterizing interfacial structure in terms of bond angle distribution functions is described. A new formulation of thermodynamic properties of interfaces is presented which focusses on the local atomic environment. Effective, temperature dependent N-body atomic interactions are derived for studying grain boundary structure at elevated temperature

  10. Charge transfer dynamics from adsorbates to surfaces with single active electron and configuration interaction based approaches

    Energy Technology Data Exchange (ETDEWEB)

    Ramakrishnan, Raghunathan, E-mail: r.ramakrishnan@unibas.ch [Institute of Physical Chemistry, National Center for Computational Design and Discovery of Novel Materials (MARVEL), Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel (Switzerland); Nest, Mathias [Theoretische Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching (Germany)

    2015-01-13

    Highlights: • We model electron dynamics across cyano alkanethiolates attached to gold cluster. • We present electron transfer time scales from TD-DFT and TD-CI based simulations. • Both DFT and CI methods qualitatively predict the trend in time scales. • TD-CI predicts the experimental relative time scale very accurately. - Abstract: We employ wavepacket simulations based on many-body time-dependent configuration interaction (TD-CI), and single active electron theories, to predict the ultrafast molecule/metal electron transfer time scales, in cyano alkanethiolates bonded to model gold clusters. The initial states represent two excited states where a valence electron is promoted to one of the two virtual π{sup ∗} molecular orbitals localized on the cyanide fragment. The ratio of the two time scales indicate the efficiency of one charge transfer channel over the other. In both our one-and many-electron simulations, this ratio agree qualitatively with each other as well as with the previously reported experimental time scales (Blobner et al., 2012), measured for a macroscopic metal surface. We study the effect of cluster size and the description of electron correlation on the charge transfer process.

  11. Hot-electron-assisted femtochemistry at surfaces: A time-dependent density functional theory approach

    DEFF Research Database (Denmark)

    Gavnholt, Jeppe; Rubio, Angel; Olsen, Thomas

    2009-01-01

    Using time-evolution time-dependent density functional theory (TDDFT) within the adiabatic local-density approximation, we study the interactions between single electrons and molecular resonances at surfaces. Our system is a nitrogen molecule adsorbed on a ruthenium surface. The surface is modeled...... at two levels of approximation, first as a simple external potential and later as a 20-atom cluster. We perform a number of calculations on an electron hitting the adsorbed molecule from inside the surface and establish a picture, where the resonance is being probed by the hot electron. This enables us...

  12. The Empowerment of Plasma Modeling by Fundamental Electron Scattering Data

    Science.gov (United States)

    Kushner, Mark J.

    2015-09-01

    Modeling of low temperature plasmas addresses at least 3 goals - investigation of fundamental processes, analysis and optimization of current technologies, and prediction of performance of as yet unbuilt systems for new applications. The former modeling may be performed on somewhat idealized systems in simple gases, while the latter will likely address geometrically and electromagnetically intricate systems with complex gas mixtures, and now gases in contact with liquids. The variety of fundamental electron and ion scattering data (FSD) required for these activities increases from the former to the latter, while the accuracy required of that data probably decreases. In each case, the fidelity, depth and impact of the modeling depends on the availability of FSD. Modeling is, in fact, empowered by the availability and robustness of FSD. In this talk, examples of the impact of and requirements for FSD in plasma modeling will be discussed from each of these three perspectives using results from multidimensional and global models. The fundamental studies will focus on modeling of inductively coupled plasmas sustained in Ar/Cl2 where the electron scattering from feed gases and their fragments ultimately determine gas temperatures. Examples of the optimization of current technologies will focus on modeling of remote plasma etching of Si and Si3N4 in Ar/NF3/N2/O2 mixtures. Modeling of systems as yet unbuilt will address the interaction of atmospheric pressure plasmas with liquids Work was supported by the US Dept. of Energy (DE-SC0001939), National Science Foundation (CHE-124752), and the Semiconductor Research Corp.

  13. Approaches and models of intercultural education

    Directory of Open Access Journals (Sweden)

    Iván Manuel Sánchez Fontalvo

    2013-10-01

    Full Text Available Needed to be aware of the need to build an intercultural society, awareness must be assumed in all social spheres, where stands the role play education. A role of transcendental, since it must promote educational spaces to form people with virtues and powers that allow them to live together / as in multicultural contexts and social diversities (sometimes uneven in an increasingly globalized and interconnected world, and foster the development of feelings of civic belonging shared before the neighborhood, city, region and country, allowing them concern and critical judgement to marginalization, poverty, misery and inequitable distribution of wealth, causes of structural violence, but at the same time, wanting to work for the welfare and transformation of these scenarios. Since these budgets, it is important to know the approaches and models of intercultural education that have been developed so far, analysing their impact on the contexts educational where apply.   

  14. Energy Space Modeling of Power Electronics in Local Area Power Networks

    Directory of Open Access Journals (Sweden)

    Gregory M. Vosters

    2012-01-01

    Full Text Available Power electronics are a core enabling technology for local area power networks and microgrids for renewable energy, telecom, data centers, and many other applications. Unfortunately, the modeling, simulation, and control of power electronics in these systems are complicated when using traditional converter models in conjunction with the network nodal equations. This work proposes a change of variables for the power electronic converter models from traditional voltage and currents to input conductance and stored energy. From this change of state, a universal point of load converter model can be utilized in the network nodal equations irrespective of the topology of the converter. The only impact the original converter topology has on the new model is the bounds on the control and state variables, and the mapping back to the switching or duty cycle controls. The proposed approach greatly simplifies the modeling of local area power networks and microgrids. This simpler model can be used to study stability and energy utilization and develop high-level control strategies that were not previously feasible.

  15. Epidemic surveillance using an electronic medical record: an empiric approach to performance improvement.

    Directory of Open Access Journals (Sweden)

    Hongzhang Zheng

    Full Text Available Electronic medical records (EMR form a rich repository of information that could benefit public health. We asked how structured and free-text narrative EMR data should be combined to improve epidemic surveillance for acute respiratory infections (ARI.Eight previously characterized ARI case detection algorithms (CDA were applied to historical EMR entries to create authentic time series of daily ARI case counts (background. An epidemic model simulated influenza cases (injection. From the time of the injection, cluster-detection statistics were applied daily on paired background+injection (combined and background-only time series. This cycle was then repeated with the injection shifted to each week of the evaluation year. We computed: a the time from injection to the first statistical alarm uniquely found in the combined dataset (Detection Delay; b how often alarms originated in the background-only dataset (false-alarm rate, or FAR; and c the number of cases found within these false alarms (Caseload. For each CDA, we plotted the Detection Delay as a function of FAR or Caseload, over a broad range of alarm thresholds.CDAs that combined text analyses seeking ARI symptoms in clinical notes with provider-assigned diagnostic codes in order to maximize the precision rather than the sensitivity of case-detection lowered Detection Delay at any given FAR or Caseload.An empiric approach can guide the integration of EMR data into case-detection methods that improve both the timeliness and efficiency of epidemic detection.

  16. Reasons for electronic cigarette use beyond cigarette smoking cessation: A concept mapping approach.

    Science.gov (United States)

    Soule, Eric K; Rosas, Scott R; Nasim, Aashir

    2016-05-01

    Electronic cigarettes (ECIGs) continue to grow in popularity, however, limited research has examined reasons for ECIG use. This study used an integrated, mixed-method participatory research approach called concept mapping (CM) to characterize and describe adults' reasons for using ECIGs. A total of 108 adults completed a multi-module online CM study that consisted of brainstorming statements about their reasons for ECIG use, sorting each statement into conceptually similar categories, and then rating each statement based on whether it represented a reason why they have used an ECIG in the past month. Participants brainstormed a total of 125 unique statements related to their reasons for ECIG use. Multivariate analyses generated a map revealing 11, interrelated components or domains that characterized their reasons for use. Importantly, reasons related to Cessation Methods, Perceived Health Benefits, Private Regard, Convenience and Conscientiousness were rated significantly higher than other categories/types of reasons related to ECIG use (p<.05). There also were significant model differences in participants' endorsement of reasons based on their demography and ECIG behaviors. This study shows that ECIG users are motivated to use ECIGs for many reasons. ECIG regulations should address these reasons for ECIG use in addition to smoking cessation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Modelling low energy electron and positron tracks in biologically relevant media

    International Nuclear Information System (INIS)

    Blanco, F.; Munoz, A.; Almeida, D.; Ferreira da Silva, F.; Limao-Vieira, P.; Fuss, M.C.; Sanz, A.G.; Garcia, G.

    2013-01-01

    This colloquium describes an approach to incorporate into radiation damage models the effect of low and intermediate energy (0-100 eV) electrons and positrons, slowing down in biologically relevant materials (water and representative biomolecules). The core of the modelling procedure is a C++ computing programme named 'Low Energy Particle Track Simulation (LEPTS)', which is compatible with available general purpose Monte Carlo packages. Input parameters are carefully selected from theoretical and experimental cross section data and energy loss distribution functions. Data sources used for this purpose are reviewed showing examples of electron and positron cross section and energy loss data for interactions with different media of increasing complexity: atoms, molecules, clusters and condense matter. Finally, we show how such a model can be used to develop an effective dosimetric tool at the molecular level (i.e. nanodosimetry). Recent experimental developments to study the fragmentation induced in biologically material by charge transfer from neutrals and negative ions are also included. (authors)

  18. Electronic conductance model in constricted MoS{sub 2} with nanopores

    Energy Technology Data Exchange (ETDEWEB)

    Sarathy, Aditya [Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, Illinois 61801 (United States); Department of Electrical and Computer Engineering, University of Illinois, Urbana, Illinois 61801 (United States); Leburton, Jean-Pierre, E-mail: jleburto@illinois.edu [Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, Illinois 61801 (United States); Department of Electrical and Computer Engineering, University of Illinois, Urbana, Illinois 61801 (United States); Department of Physics, University of Illinois, Urbana, Illinois 61801 (United States)

    2016-02-01

    We describe a self-consistent model for electronic transport in a molybdenum di-sulphide (MoS{sub 2}) layer containing a nanopore in a constricted geometry. Our approach is based on a semi-classical thermionic Poisson-Boltzmann technique using a two-valley model within the effective mass approximation to investigate perturbations caused by the nanopore on the electronic current. In particular, we show that the effect of the nanopore on the conductance is reduced as the nanopore is moved from the center to the layer edges. Our model is applied to the detection of DNA translocating through the nanopore, which reveals current features similar to those as predicted in nanopore graphene layers.

  19. Modeling the high-energy electronic state manifold of adenine: Calibration for nonlinear electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nenov, Artur, E-mail: Artur.Nenov@unibo.it; Giussani, Angelo; Segarra-Martí, Javier; Jaiswal, Vishal K. [Dipartimento di Chimica “G. Ciamician,” Università di Bologna, Via Selmi 2, IT-40126 Bologna (Italy); Rivalta, Ivan [Université de Lyon, CNRS, Institut de Chimie de Lyon, École Normale Supérieure de Lyon, 46 Allée d’Italie, F-69364 Lyon Cedex 07 (France); Cerullo, Giulio [Dipartimento di Fisica, Politecnico di Milano, IFN-CNR, Piazza Leonardo Da Vinci 32, IT-20133 Milano (Italy); Mukamel, Shaul [Department of Chemistry, University of California, Irvine, California 92697-2025 (United States); Garavelli, Marco, E-mail: marco.garavelli@unibo.it, E-mail: marco.garavelli@ens-lyon.fr [Dipartimento di Chimica “G. Ciamician,” Università di Bologna, Via Selmi 2, IT-40126 Bologna (Italy); Université de Lyon, CNRS, Institut de Chimie de Lyon, École Normale Supérieure de Lyon, 46 Allée d’Italie, F-69364 Lyon Cedex 07 (France)

    2015-06-07

    Pump-probe electronic spectroscopy using femtosecond laser pulses has evolved into a standard tool for tracking ultrafast excited state dynamics. Its two-dimensional (2D) counterpart is becoming an increasingly available and promising technique for resolving many of the limitations of pump-probe caused by spectral congestion. The ability to simulate pump-probe and 2D spectra from ab initio computations would allow one to link mechanistic observables like molecular motions and the making/breaking of chemical bonds to experimental observables like excited state lifetimes and quantum yields. From a theoretical standpoint, the characterization of the electronic transitions in the visible (Vis)/ultraviolet (UV), which are excited via the interaction of a molecular system with the incoming pump/probe pulses, translates into the determination of a computationally challenging number of excited states (going over 100) even for small/medium sized systems. A protocol is therefore required to evaluate the fluctuations of spectral properties like transition energies and dipole moments as a function of the computational parameters and to estimate the effect of these fluctuations on the transient spectral appearance. In the present contribution such a protocol is presented within the framework of complete and restricted active space self-consistent field theory and its second-order perturbation theory extensions. The electronic excited states of adenine have been carefully characterized through a previously presented computational recipe [Nenov et al., Comput. Theor. Chem. 1040–1041, 295-303 (2014)]. A wise reduction of the level of theory has then been performed in order to obtain a computationally less demanding approach that is still able to reproduce the characteristic features of the reference data. Foreseeing the potentiality of 2D electronic spectroscopy to track polynucleotide ground and excited state dynamics, and in particular its expected ability to provide

  20. Modeling the high-energy electronic state manifold of adenine: Calibration for nonlinear electronic spectroscopy

    Science.gov (United States)

    Nenov, Artur; Giussani, Angelo; Segarra-Martí, Javier; Jaiswal, Vishal K.; Rivalta, Ivan; Cerullo, Giulio; Mukamel, Shaul; Garavelli, Marco

    2015-06-01

    Pump-probe electronic spectroscopy using femtosecond laser pulses has evolved into a standard tool for tracking ultrafast excited state dynamics. Its two-dimensional (2D) counterpart is becoming an increasingly available and promising technique for resolving many of the limitations of pump-probe caused by spectral congestion. The ability to simulate pump-probe and 2D spectra from ab initio computations would allow one to link mechanistic observables like molecular motions and the making/breaking of chemical bonds to experimental observables like excited state lifetimes and quantum yields. From a theoretical standpoint, the characterization of the electronic transitions in the visible (Vis)/ultraviolet (UV), which are excited via the interaction of a molecular system with the incoming pump/probe pulses, translates into the determination of a computationally challenging number of excited states (going over 100) even for small/medium sized systems. A protocol is therefore required to evaluate the fluctuations of spectral properties like transition energies and dipole moments as a function of the computational parameters and to estimate the effect of these fluctuations on the transient spectral appearance. In the present contribution such a protocol is presented within the framework of complete and restricted active space self-consistent field theory and its second-order perturbation theory extensions. The electronic excited states of adenine have been carefully characterized through a previously presented computational recipe [Nenov et al., Comput. Theor. Chem. 1040-1041, 295-303 (2014)]. A wise reduction of the level of theory has then been performed in order to obtain a computationally less demanding approach that is still able to reproduce the characteristic features of the reference data. Foreseeing the potentiality of 2D electronic spectroscopy to track polynucleotide ground and excited state dynamics, and in particular its expected ability to provide

  1. Fabrication Approaches to Interconnect Based Devices for Stretchable Electronics: A Review

    Science.gov (United States)

    Nagels, Steven

    2018-01-01

    Stretchable electronics promise to naturalize the way that we are surrounded by and interact with our devices. Sensors that can stretch and bend furthermore have become increasingly relevant as the technology behind them matures rapidly from lab-based workflows to industrially applicable production principles. Regardless of the specific materials used, creating stretchable conductors involves either the implementation of strain reliefs through insightful geometric patterning, the dispersion of stiff conductive filler in an elastomeric matrix, or the employment of intrinsically stretchable conductive materials. These basic principles however have spawned a myriad of materials systems wherein future application engineers need to find their way. This paper reports a literature study on the spectrum of different approaches towards stretchable electronics, discusses standardization of characteristic tests together with their reports and estimates matureness for industry. Patterned copper foils that are embedded in elastomeric sheets, which are closest to conventional electronic circuits processing, make up one end of the spectrum. Furthest from industry are the more recent circuits based on intrinsically stretchable liquid metals. These show extremely promising results, however, as a technology, liquid metal is not mature enough to be adapted. Printing makes up the transition between both ends, and is also well established on an industrial level, but traditionally not linked to creating electronics. Even though a certain level of maturity was found amongst the approaches that are reviewed herein, industrial adaptation for consumer electronics remains unpredictable without a designated break-through commercial application. PMID:29510497

  2. Fabrication Approaches to Interconnect Based Devices for Stretchable Electronics: A Review.

    Science.gov (United States)

    Nagels, Steven; Deferme, Wim

    2018-03-03

    Stretchable electronics promise to naturalize the way that we are surrounded by and interact with our devices. Sensors that can stretch and bend furthermore have become increasingly relevant as the technology behind them matures rapidly from lab-based workflows to industrially applicable production principles. Regardless of the specific materials used, creating stretchable conductors involves either the implementation of strain reliefs through insightful geometric patterning, the dispersion of stiff conductive filler in an elastomeric matrix, or the employment of intrinsically stretchable conductive materials. These basic principles however have spawned a myriad of materials systems wherein future application engineers need to find their way. This paper reports a literature study on the spectrum of different approaches towards stretchable electronics, discusses standardization of characteristic tests together with their reports and estimates matureness for industry. Patterned copper foils that are embedded in elastomeric sheets, which are closest to conventional electronic circuits processing, make up one end of the spectrum. Furthest from industry are the more recent circuits based on intrinsically stretchable liquid metals. These show extremely promising results, however, as a technology, liquid metal is not mature enough to be adapted. Printing makes up the transition between both ends, and is also well established on an industrial level, but traditionally not linked to creating electronics. Even though a certain level of maturity was found amongst the approaches that are reviewed herein, industrial adaptation for consumer electronics remains unpredictable without a designated break-through commercial application.

  3. Fabrication Approaches to Interconnect Based Devices for Stretchable Electronics: A Review

    Directory of Open Access Journals (Sweden)

    Steven Nagels

    2018-03-01

    Full Text Available Stretchable electronics promise to naturalize the way that we are surrounded by and interact with our devices. Sensors that can stretch and bend furthermore have become increasingly relevant as the technology behind them matures rapidly from lab-based workflows to industrially applicable production principles. Regardless of the specific materials used, creating stretchable conductors involves either the implementation of strain reliefs through insightful geometric patterning, the dispersion of stiff conductive filler in an elastomeric matrix, or the employment of intrinsically stretchable conductive materials. These basic principles however have spawned a myriad of materials systems wherein future application engineers need to find their way. This paper reports a literature study on the spectrum of different approaches towards stretchable electronics, discusses standardization of characteristic tests together with their reports and estimates matureness for industry. Patterned copper foils that are embedded in elastomeric sheets, which are closest to conventional electronic circuits processing, make up one end of the spectrum. Furthest from industry are the more recent circuits based on intrinsically stretchable liquid metals. These show extremely promising results, however, as a technology, liquid metal is not mature enough to be adapted. Printing makes up the transition between both ends, and is also well established on an industrial level, but traditionally not linked to creating electronics. Even though a certain level of maturity was found amongst the approaches that are reviewed herein, industrial adaptation for consumer electronics remains unpredictable without a designated break-through commercial application.

  4. Systems Approaches to Modeling Chronic Mucosal Inflammation

    Science.gov (United States)

    Gao, Boning; Choudhary, Sanjeev; Wood, Thomas G.; Carmical, Joseph R.; Boldogh, Istvan; Mitra, Sankar; Minna, John D.; Brasier, Allan R.

    2013-01-01

    The respiratory mucosa is a major coordinator of the inflammatory response in chronic airway diseases, including asthma and chronic obstructive pulmonary disease (COPD). Signals produced by the chronic inflammatory process induce epithelial mesenchymal transition (EMT) that dramatically alters the epithelial cell phenotype. The effects of EMT on epigenetic reprogramming and the activation of transcriptional networks are known, its effects on the innate inflammatory response are underexplored. We used a multiplex gene expression profiling platform to investigate the perturbations of the innate pathways induced by TGFβ in a primary airway epithelial cell model of EMT. EMT had dramatic effects on the induction of the innate pathway and the coupling interval of the canonical and noncanonical NF-κB pathways. Simulation experiments demonstrate that rapid, coordinated cap-independent translation of TRAF-1 and NF-κB2 is required to reduce the noncanonical pathway coupling interval. Experiments using amantadine confirmed the prediction that TRAF-1 and NF-κB2/p100 production is mediated by an IRES-dependent mechanism. These data indicate that the epigenetic changes produced by EMT induce dynamic state changes of the innate signaling pathway. Further applications of systems approaches will provide understanding of this complex phenotype through deterministic modeling and multidimensional (genomic and proteomic) profiling. PMID:24228254

  5. ECOMOD - An ecological approach to radioecological modelling

    International Nuclear Information System (INIS)

    Sazykina, Tatiana G.

    2000-01-01

    A unified methodology is proposed to simulate the dynamic processes of radionuclide migration in aquatic food chains in parallel with their stable analogue elements. The distinguishing feature of the unified radioecological/ecological approach is the description of radionuclide migration along with dynamic equations for the ecosystem. The ability of the methodology to predict the results of radioecological experiments is demonstrated by an example of radionuclide (iron group) accumulation by a laboratory culture of the algae Platymonas viridis. Based on the unified methodology, the 'ECOMOD' radioecological model was developed to simulate dynamic radioecological processes in aquatic ecosystems. It comprises three basic modules, which are operated as a set of inter-related programs. The 'ECOSYSTEM' module solves non-linear ecological equations, describing the biomass dynamics of essential ecosystem components. The 'RADIONUCLIDE DISTRIBUTION' module calculates the radionuclide distribution in abiotic and biotic components of the aquatic ecosystem. The 'DOSE ASSESSMENT' module calculates doses to aquatic biota and doses to man from aquatic food chains. The application of the ECOMOD model to reconstruct the radionuclide distribution in the Chernobyl Cooling Pond ecosystem in the early period after the accident shows good agreement with observations

  6. Modeling Radiation Belt Electron Dynamics with the DREAM3D Diffusion Model

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Weichao [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cunningham, Gregory S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chen, Yue [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Henderson, Michael G. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Morley, Steven K. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reeves, Geoffrey D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Blake, Bernard J. [The Aerospace Corporation, El Segundo, CA (United States); Baker, Daniel N. [Lab. for Atmospheric and Space Physics, Boulder, CO (United States); Spence, Harlan [Univ. of New Hampshire, Durham, NH (United States)

    2014-02-14

    The simulation results from our 3D diffusion model on the CRRES era suggest; our model captures the general variations of radiation belt electrons, including the dropouts and the enhancements; the overestimations inside the plasmapause can be improved by increasing the PA diffusion from hiss waves; and that better DLL and wave models are required.

  7. A Bayesian network model for predicting type 2 diabetes risk based on electronic health records

    Science.gov (United States)

    Xie, Jiang; Liu, Yan; Zeng, Xu; Zhang, Wu; Mei, Zhen

    2017-07-01

    An extensive, in-depth study of diabetes risk factors (DBRF) is of crucial importance to prevent (or reduce) the chance of suffering from type 2 diabetes (T2D). Accumulation of electronic health records (EHRs) makes it possible to build nonlinear relationships between risk factors and diabetes. However, the current DBRF researches mainly focus on qualitative analyses, and the inconformity of physical examination items makes the risk factors likely to be lost, which drives us to study the novel machine learning approach for risk model development. In this paper, we use Bayesian networks (BNs) to analyze the relationship between physical examination information and T2D, and to quantify the link between risk factors and T2D. Furthermore, with the quantitative analyses of DBRF, we adopt EHR and propose a machine learning approach based on BNs to predict the risk of T2D. The experiments demonstrate that our approach can lead to better predictive performance than the classical risk model.

  8. An ab initio model of electron transport in hematite (a-Fe2O3) basal planes

    International Nuclear Information System (INIS)

    Rosso, Kevin M.; Smith, Dayle MA; Dupuis, Michel

    2003-01-01

    Transport of conduction electrons through basal planes of the hematite lattice was modeled as a valence alternation of iron cations using ab initio molecular orbital calculations and electron transfer theory. A cluster approach was successfully implemented to compute electron transfer rate-controlling quantities such as the reorganization energy and electronic coupling matrix element. Localization of a conduction electron at an iron lattice site is accompanied by large iron/oxygen bond length increases that give rise to a large inner-sphere component of the reorganization energy. The interaction between the reactant and product electronic states in the crossing?point configuration is substantial and leads to an adiabatic electron transfer system. Electron transfer is predicted to possess a small positive activation energy that turns out to be in excellent agreement with values deduced from conductivity measurements. Measured electron mobility can be explained in terms of nearest neighbor electron hops without significant contribution from iron atoms further away. Comparison of the predicted maximum polaron binding energy with the predicted half bandwidth indicates compliance with the small polaron condition. Therefore the localized electron treatment is appropriate to describe electron transport in this system

  9. Direct electron transfer: an approach for electrochemical biosensors with higher selectivity and sensitivity

    Directory of Open Access Journals (Sweden)

    Freire Renato S.

    2003-01-01

    Full Text Available The most promising approach for the development of electrochemical biosensors is to establish a direct electrical communication between the biomolecules and the electrode surface. This review focuses on advances, directions and strategies in the development of third generation electrochemical biosensors. Subjects covered include a brief description of the fundamentals of the electron transfer phenomenon and amperometric biosensor development (different types and new oriented enzyme immobilization techniques. Special attention is given to different redox enzymes and proteins capable of electrocatalyzing reactions via direct electron transfer. The analytical applications and future trends for third generation biosensors are also presented and discussed.

  10. A unifying probabilistic Bayesian approach to derive electron density from MRI for radiation therapy treatment planning

    International Nuclear Information System (INIS)

    Gudur, Madhu Sudhan Reddy; Hara, Wendy; Le, Quynh-Thu; Wang, Lei; Xing, Lei; Li, Ruijiang

    2014-01-01

    MRI significantly improves the accuracy and reliability of target delineation in radiation therapy for certain tumors due to its superior soft tissue contrast compared to CT. A treatment planning process with MRI as the sole imaging modality will eliminate systematic CT/MRI co-registration errors, reduce cost and radiation exposure, and simplify clinical workflow. However, MRI lacks the key electron density information necessary for accurate dose calculation and generating reference images for patient setup. The purpose of this work is to develop a unifying method to derive electron density from standard T1-weighted MRI. We propose to combine both intensity and geometry information into a unifying probabilistic Bayesian framework for electron density mapping. For each voxel, we compute two conditional probability density functions (PDFs) of electron density given its: (1) T1-weighted MRI intensity, and (2) geometry in a reference anatomy, obtained by deformable image registration between the MRI of the atlas and test patient. The two conditional PDFs containing intensity and geometry information are combined into a unifying posterior PDF, whose mean value corresponds to the optimal electron density value under the mean-square error criterion. We evaluated the algorithm’s accuracy of electron density mapping and its ability to detect bone in the head for eight patients, using an additional patient as the atlas or template. Mean absolute HU error between the estimated and true CT, as well as receiver operating characteristics for bone detection (HU > 200) were calculated. The performance was compared with a global intensity approach based on T1 and no density correction (set whole head to water). The proposed technique significantly reduced the errors in electron density estimation, with a mean absolute HU error of 126, compared with 139 for deformable registration (p = 2  ×  10 −4 ), 283 for the intensity approach (p = 2  ×  10 −6 ) and 282

  11. Quantum ion acoustic solitary waves in electron-ion plasmas: A Sagdeev potential approach

    International Nuclear Information System (INIS)

    Mahmood, S.; Mushtaq, A.

    2008-01-01

    Linear and nonlinear ion acoustic waves are studied in unmagnetized electron-ion quantum plasmas. Sagdeev potential approach is employed to describe the nonlinear quantum ion acoustic waves. It is found that density dips structures are formed in the subsonic region in a electron-ion quantum plasma case. The amplitude of the nonlinear structures remains constant and the width is broadened with the increase in the quantization of the system. However, the nonlinear wave amplitude is reduced with the increase in the wave Mach number. The numerical results are also presented

  12. A unifying probabilistic Bayesian approach to derive electron density from MRI for radiation therapy treatment planning

    Science.gov (United States)

    Sudhan Reddy Gudur, Madhu; Hara, Wendy; Le, Quynh-Thu; Wang, Lei; Xing, Lei; Li, Ruijiang

    2014-11-01

    MRI significantly improves the accuracy and reliability of target delineation in radiation therapy for certain tumors due to its superior soft tissue contrast compared to CT. A treatment planning process with MRI as the sole imaging modality will eliminate systematic CT/MRI co-registration errors, reduce cost and radiation exposure, and simplify clinical workflow. However, MRI lacks the key electron density information necessary for accurate dose calculation and generating reference images for patient setup. The purpose of this work is to develop a unifying method to derive electron density from standard T1-weighted MRI. We propose to combine both intensity and geometry information into a unifying probabilistic Bayesian framework for electron density mapping. For each voxel, we compute two conditional probability density functions (PDFs) of electron density given its: (1) T1-weighted MRI intensity, and (2) geometry in a reference anatomy, obtained by deformable image registration between the MRI of the atlas and test patient. The two conditional PDFs containing intensity and geometry information are combined into a unifying posterior PDF, whose mean value corresponds to the optimal electron density value under the mean-square error criterion. We evaluated the algorithm’s accuracy of electron density mapping and its ability to detect bone in the head for eight patients, using an additional patient as the atlas or template. Mean absolute HU error between the estimated and true CT, as well as receiver operating characteristics for bone detection (HU > 200) were calculated. The performance was compared with a global intensity approach based on T1 and no density correction (set whole head to water). The proposed technique significantly reduced the errors in electron density estimation, with a mean absolute HU error of 126, compared with 139 for deformable registration (p = 2  ×  10-4), 283 for the intensity approach (p = 2  ×  10-6) and 282 without density

  13. Modeling molecular acidity with electronic properties and Hammett constants for substituted benzoic acids.

    Science.gov (United States)

    Huang, Ying; Liu, Lianghong; Liu, Wanhui; Liu, Shaogang; Liu, Shubin

    2011-12-29

    Molecular acidity is an important physiochemical property essential in many fields of molecular studies, but an efficient and reliable computational approach to make accurate predictions is still missing. In this work, based on our previous studies to use gas phase electronic properties such as molecular electrostatic potential and valence natural atomic orbitals of the acidic atom and leaving proton, we demonstrate here that different approaches can be employed to tackle this problem. To that end, we employ 196 singly, doubly, and triply substituted benzoic acids for the study. We show that two different approaches are possible, one focusing on the carboxyl group through its localized electronic properties and the other on the substituting groups via Hammett constants and their additivity rule. Our present results clearly exhibit that with the linear models built from the singly substituted species, one can accurately predict the pK(a) values for the doubly and triply substituted species with both of these two approaches. The predictions from these approaches are consistent with each other and agree well with the experimental data. These intrinsically different approaches are the two manifestations of the same molecular acidity property, both valid and complementary to each other. © 2011 American Chemical Society

  14. Electronic Commerce Success Model: A Search for Multiple Criteria

    Directory of Open Access Journals (Sweden)

    Didi Achjari

    2004-01-01

    Full Text Available The current study attempts to develop and examine framework of e-commerce success. In order to obtain comprehensive and robust measures, the framework accomodates key factors that are identified in the literature concerning the success of electronic commerce. The structural model comprises of four exogenous variables (Internal Driver, Internal Impediment, External Driver and Exgternal Impediment and one endogenous variable (Electornic Commerce Success eith 24 observed variables. The study that was administered within large Australian companies using questionaire survey concluded that benefits for both internal organization and external parties from the use of e-commerce were the main factor tro predict perceived and/or expected success of electronic commerce.

  15. An atomic model of brome mosaic virus using direct electron detection and real-space optimization

    Science.gov (United States)

    Wang, Zhao; Hryc, Corey F.; Bammes, Benjamin; Afonine, Pavel V.; Jakana, Joanita; Chen, Dong-Hua; Liu, Xiangan; Baker, Matthew L.; Kao, Cheng; Ludtke, Steven J.; Schmid, Michael F.; Adams, Paul D.; Chiu, Wah

    2014-09-01

    Advances in electron cryo-microscopy have enabled structure determination of macromolecules at near-atomic resolution. However, structure determination, even using de novo methods, remains susceptible to model bias and overfitting. Here we describe a complete workflow for data acquisition, image processing, all-atom modelling and validation of brome mosaic virus, an RNA virus. Data were collected with a direct electron detector in integrating mode and an exposure beyond the traditional radiation damage limit. The final density map has a resolution of 3.8 Å as assessed by two independent data sets and maps. We used the map to derive an all-atom model with a newly implemented real-space optimization protocol. The validity of the model was verified by its match with the density map and a previous model from X-ray crystallography, as well as the internal consistency of models from independent maps. This study demonstrates a practical approach to obtain a rigorously validated atomic resolution electron cryo-microscopy structure.

  16. An atomic model of brome mosaic virus using direct electron detection and real-space optimization.

    Science.gov (United States)

    Wang, Zhao; Hryc, Corey F; Bammes, Benjamin; Afonine, Pavel V; Jakana, Joanita; Chen, Dong-Hua; Liu, Xiangan; Baker, Matthew L; Kao, Cheng; Ludtke, Steven J; Schmid, Michael F; Adams, Paul D; Chiu, Wah

    2014-09-04

    Advances in electron cryo-microscopy have enabled structure determination of macromolecules at near-atomic resolution. However, structure determination, even using de novo methods, remains susceptible to model bias and overfitting. Here we describe a complete workflow for data acquisition, image processing, all-atom modelling and validation of brome mosaic virus, an RNA virus. Data were collected with a direct electron detector in integrating mode and an exposure beyond the traditional radiation damage limit. The final density map has a resolution of 3.8 Å as assessed by two independent data sets and maps. We used the map to derive an all-atom model with a newly implemented real-space optimization protocol. The validity of the model was verified by its match with the density map and a previous model from X-ray crystallography, as well as the internal consistency of models from independent maps. This study demonstrates a practical approach to obtain a rigorously validated atomic resolution electron cryo-microscopy structure.

  17. Spintronic device modeling and evaluation using modular approach to spintronics

    Science.gov (United States)

    Ganguly, Samiran

    Spintronics technology finds itself in an exciting stage today. Riding on the backs of rapid growth and impressive advances in materials and phenomena, it has started to make headway in the memory industry as solid state magnetic memories (STT-MRAM) and is considered a possible candidate to replace the CMOS when its scaling reaches physical limits. It is necessary to bring all these advances together in a coherent fashion to explore and evaluate the potential of spintronic devices. This work creates a framework for this exploration and evaluation based on Modular Approach to Spintronics, which encapsulate the physics of transport of charge and spin through materials and the phenomenology of magnetic dynamics and interaction in benchmarked elemental modules. These modules can then be combined together to form spin-circuit models of complex spintronic devices and structures which can be simulated using SPICE like circuit simulators. In this work we demonstrate how Modular Approach to Spintronics can be used to build spin-circuit models of functional spintronic devices of all types: memory, logic, and oscillators. We then show how Modular Approach to Spintronics can help identify critical factors behind static and dynamic dissipation in spintronic devices and provide remedies by exploring the use of various alternative materials and phenomena. Lastly, we show the use of Modular Approach to Spintronics in exploring new paradigms of computing enabled by the inherent physics of spintronic devices. We hope that this work will encourage more research and experiments that will establish spintronics as a viable technology for continued advancement of electronics.

  18. Integrated Nationwide Electronic Health Records system: Semi-distributed architecture approach.

    Science.gov (United States)

    Fragidis, Leonidas L; Chatzoglou, Prodromos D; Aggelidis, Vassilios P

    2016-11-14

    The integration of heterogeneous electronic health records systems by building an interoperable nationwide electronic health record system provides undisputable benefits in health care, like superior health information quality, medical errors prevention and cost saving. This paper proposes a semi-distributed system architecture approach for an integrated national electronic health record system incorporating the advantages of the two dominant approaches, the centralized architecture and the distributed architecture. The high level design of the main elements for the proposed architecture is provided along with diagrams of execution and operation and data synchronization architecture for the proposed solution. The proposed approach effectively handles issues related to redundancy, consistency, security, privacy, availability, load balancing, maintainability, complexity and interoperability of citizen's health data. The proposed semi-distributed architecture offers a robust interoperability framework without healthcare providers to change their local EHR systems. It is a pragmatic approach taking into account the characteristics of the Greek national healthcare system along with the national public administration data communication network infrastructure, for achieving EHR integration with acceptable implementation cost.

  19. Modeling radiation belt electron dynamics during GEM challenge intervals with the DREAM3D diffusion model

    Science.gov (United States)

    Tu, Weichao; Cunningham, G. S.; Chen, Y.; Henderson, M. G.; Camporeale, E.; Reeves, G. D.

    2013-10-01

    a response to the Geospace Environment Modeling (GEM) "Global Radiation Belt Modeling Challenge," a 3D diffusion model is used to simulate the radiation belt electron dynamics during two intervals of the Combined Release and Radiation Effects Satellite (CRRES) mission, 15 August to 15 October 1990 and 1 February to 31 July 1991. The 3D diffusion model, developed as part of the Dynamic Radiation Environment Assimilation Model (DREAM) project, includes radial, pitch angle, and momentum diffusion and mixed pitch angle-momentum diffusion, which are driven by dynamic wave databases from the statistical CRRES wave data, including plasmaspheric hiss, lower-band, and upper-band chorus. By comparing the DREAM3D model outputs to the CRRES electron phase space density (PSD) data, we find that, with a data-driven boundary condition at Lmax = 5.5, the electron enhancements can generally be explained by radial diffusion, though additional local heating from chorus waves is required. Because the PSD reductions are included in the boundary condition at Lmax = 5.5, our model captures the fast electron dropouts over a large L range, producing better model performance compared to previous published results. Plasmaspheric hiss produces electron losses inside the plasmasphere, but the model still sometimes overestimates the PSD there. Test simulations using reduced radial diffusion coefficients or increased pitch angle diffusion coefficients inside the plasmasphere suggest that better wave models and more realistic radial diffusion coefficients, both inside and outside the plasmasphere, are needed to improve the model performance. Statistically, the results show that, with the data-driven outer boundary condition, including radial diffusion and plasmaspheric hiss is sufficient to model the electrons during geomagnetically quiet times, but to best capture the radiation belt variations during active times, pitch angle and momentum diffusion from chorus waves are required.

  20. Electron reactions in model liquids and biological systems

    International Nuclear Information System (INIS)

    Bakale, G.; Gregg, E.C.

    1982-01-01

    Progress is reported in the following studies: (1) Field-dependent electron attachment; (2) Dependence of electron attachment rate on electron-acceptor dipole moment; (3) Electron attachment in i-octane/TMS mixtures; (4) Electron attachment/detachment equilibria; (5) Electron attachment to reversed micelles; (6) Electron attachment to chemical carcinogens; (7) Radiation-induced bacterial mutagenesis; and (8) Bacterial mutagenicity of nitrobenzene derivatives. 14 references

  1. Modelling of electron transport and of sawtooth activity in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Angioni, C

    2001-10-01

    Transport phenomena in tokamak plasmas strongly limit the particle and energy confinement and represent a crucial obstacle to controlled thermonuclear fusion. Within the vast framework of transport studies, three topics have been tackled in the present thesis: first, the computation of neoclassical transport coefficients for general axisymmetric equilibria and arbitrary collisionality regime; second, the analysis of the electron temperature behaviour and transport modelling of plasma discharges in the Tokamak a configuration Variable (TCV); third, the modelling and simulation of the sawtooth activity with different plasma heating conditions. The work dedicated to neoclassical theory has been undertaken in order to first analytically identify a set of equations suited for implementation in existing Fokker-Planck codes. Modifications of these codes enabled us to compute the neoclassical transport coefficients considering different realistic magnetic equilibrium configurations and covering a large range of variation of three key parameters: aspect ratio, collisionality, and effective charge number. A comparison of the numerical results with an analytical limit has permitted the identification of two expressions for the trapped particle fraction, capable of encapsulating the geometrical effects and thus enabling each transport coefficient to be fitted with a single analytical function. This has allowed us to provide simple analytical formulae for all the neoclassical transport coefficients valid for arbitrary aspect ratio and collisionality in general realistic geometry. This work is particularly useful for a correct evaluation of the neoclassical contribution in tokamak scenarios with large bootstrap cur- rent fraction, or improved confinement regimes with low anomalous transport and for the determination of the plasma current density profile, since the plasma conductivity is usually assumed neoclassical. These results have been included in the plasma transport code

  2. Electronic structure of vitamin B12 within the framework of the Haldane-Anderson impurity model

    Science.gov (United States)

    Kandemir, Zafer; Mayda, Selma; Bulut, Nejat

    2015-03-01

    We study the electronic structure of vitamin B12 (cyanocobalamine C63H88CoN14O14P) by using the framework of the multi-orbital single-impurity Haldane-Anderson model of a transition-metal impurity in a semiconductor host. Here, our purpose is to understand the many-body effects originating from the transition-metal impurity. In this approach, the cobalt 3 d orbitals are treated as the impurity states placed in a semiconductor host which consists of the rest of the molecule. The parameters of the resulting effective Haldane-Anderson model are obtained within the Hartree-Fock approximation for the electronic structure of the molecule. The quantum Monte Carlo technique is then used to calculate the one-electron and magnetic correlation functions of this effective Haldane-Anderson model for vitamin B12. We find that new states form inside the semiconductor gap due to the on-site Coulomb interaction at the impurity 3 d orbitals and that these states become the highest occupied molecular orbitals. In addition, we present results on the charge distribution and spin correlations around the Co atom. We compare the results of this approach with those obtained by the density-functional theory calculations.

  3. Quality assessment of Isfahan Medical Faculty web site electronic services and prioritizing solutions using analytic hierarchy process approach.

    Science.gov (United States)

    Hajrahimi, Nafiseh; Dehaghani, Sayed Mehdi Hejazi; Hajrahimi, Nargess; Sarmadi, Sima

    2014-01-01

    Implementing information technology in the best possible way can bring many advantages such as applying electronic services and facilitating tasks. Therefore, assessment of service providing systems is a way to improve the quality and elevate these systems including e-commerce, e-government, e-banking, and e-learning. This study was aimed to evaluate the electronic services in the website of Isfahan University of Medical Sciences in order to propose solutions to improve them. Furthermore, we aim to rank the solutions based on the factors that enhance the quality of electronic services by using analytic hierarchy process (AHP) method. Non-parametric test was used to assess the quality of electronic services. The assessment of propositions was based on Aqual model and they were prioritized using AHP approach. The AHP approach was used because it directly applies experts' deductions in the model, and lead to more objective results in the analysis and prioritizing the risks. After evaluating the quality of the electronic services, a multi-criteria decision making frame-work was used to prioritize the proposed solutions. Non-parametric tests and AHP approach using Expert Choice software. The results showed that students were satisfied in most of the indicators. Only a few indicators received low satisfaction from students including, design attractiveness, the amount of explanation and details of information, honesty and responsiveness of authorities, and the role of e-services in the user's relationship with university. After interviewing with Information and Communications Technology (ICT) experts at the university, measurement criteria, and solutions to improve the quality were collected. The best solutions were selected by EC software. According to the results, the solution "controlling and improving the process in handling users complaints" is of the utmost importance and authorities have to have it on the website and place great importance on updating this process

  4. Modeling healthcare authorization and claim submissions using the openEHR dual-model approach

    Science.gov (United States)

    2011-01-01

    Background The TISS standard is a set of mandatory forms and electronic messages for healthcare authorization and claim submissions among healthcare plans and providers in Brazil. It is not based on formal models as the new generation of health informatics standards suggests. The objective of this paper is to model the TISS in terms of the openEHR archetype-based approach and integrate it into a patient-centered EHR architecture. Methods Three approaches were adopted to model TISS. In the first approach, a set of archetypes was designed using ENTRY subclasses. In the second one, a set of archetypes was designed using exclusively ADMIN_ENTRY and CLUSTERs as their root classes. In the third approach, the openEHR ADMIN_ENTRY is extended with classes designed for authorization and claim submissions, and an ISM_TRANSITION attribute is added to the COMPOSITION class. Another set of archetypes was designed based on this model. For all three approaches, templates were designed to represent the TISS forms. Results The archetypes based on the openEHR RM (Reference Model) can represent all TISS data structures. The extended model adds subclasses and an attribute to the COMPOSITION class to represent information on authorization and claim submissions. The archetypes based on all three approaches have similar structures, although rooted in different classes. The extended openEHR RM model is more semantically aligned with the concepts involved in a claim submission, but may disrupt interoperability with other systems and the current tools must be adapted to deal with it. Conclusions Modeling the TISS standard by means of the openEHR approach makes it aligned with ISO recommendations and provides a solid foundation on which the TISS can evolve. Although there are few administrative archetypes available, the openEHR RM is expressive enough to represent the TISS standard. This paper focuses on the TISS but its results may be extended to other billing processes. A complete

  5. Modeling healthcare authorization and claim submissions using the openEHR dual-model approach

    Directory of Open Access Journals (Sweden)

    Freire Sergio M

    2011-10-01

    Full Text Available Abstract Background The TISS standard is a set of mandatory forms and electronic messages for healthcare authorization and claim submissions among healthcare plans and providers in Brazil. It is not based on formal models as the new generation of health informatics standards suggests. The objective of this paper is to model the TISS in terms of the openEHR archetype-based approach and integrate it into a patient-centered EHR architecture. Methods Three approaches were adopted to model TISS. In the first approach, a set of archetypes was designed using ENTRY subclasses. In the second one, a set of archetypes was designed using exclusively ADMIN_ENTRY and CLUSTERs as their root classes. In the third approach, the openEHR ADMIN_ENTRY is extended with classes designed for authorization and claim submissions, and an ISM_TRANSITION attribute is added to the COMPOSITION class. Another set of archetypes was designed based on this model. For all three approaches, templates were designed to represent the TISS forms. Results The archetypes based on the openEHR RM (Reference Model can represent all TISS data structures. The extended model adds subclasses and an attribute to the COMPOSITION class to represent information on authorization and claim submissions. The archetypes based on all three approaches have similar structures, although rooted in different classes. The extended openEHR RM model is more semantically aligned with the concepts involved in a claim submission, but may disrupt interoperability with other systems and the current tools must be adapted to deal with it. Conclusions Modeling the TISS standard by means of the openEHR approach makes it aligned with ISO recommendations and provides a solid foundation on which the TISS can evolve. Although there are few administrative archetypes available, the openEHR RM is expressive enough to represent the TISS standard. This paper focuses on the TISS but its results may be extended to other billing

  6. Electron/muon specific two Higgs doublet model

    Energy Technology Data Exchange (ETDEWEB)

    Kajiyama, Yuji, E-mail: kajiyama-yuuji@akita-pref.ed.jp [Akita Highschool, Tegata-Nakadai 1, Akita, 010-0851 (Japan); Okada, Hiroshi, E-mail: hokada@kias.re.kr [School of Physics, KIAS, Seoul 130-722 (Korea, Republic of); Yagyu, Kei, E-mail: keiyagyu@ncu.edu.tw [Department of Physics, National Central University, Chungli, 32001, Taiwan, ROC (China)

    2014-10-15

    We discuss two Higgs doublet models with a softly-broken discrete S{sub 3} symmetry, where the mass matrix for charged-leptons is predicted as the diagonal form in the weak eigenbasis of lepton fields. Similarly to an introduction of Z{sub 2} symmetry, the tree level flavor changing neutral current can be forbidden by imposing the S{sub 3} symmetry to the model. Under the S{sub 3} symmetry, there are four types of Yukawa interactions depending on the S{sub 3} charge assignment to right-handed fermions. We find that extra Higgs bosons can be muon and electron specific in one of four types of the Yukawa interaction. This property does not appear in any other two Higgs doublet models with a softly-broken Z{sub 2} symmetry. We discuss the phenomenology of the muon and electron specific Higgs bosons at the Large Hadron Collider; namely we evaluate allowed parameter regions from the current Higgs boson search data and discovery potential of such a Higgs boson at the 14 TeV run.

  7. Understanding valence-shell electron-pair repulsion (VSEPR) theory using origami molecular models

    Science.gov (United States)

    Endah Saraswati, Teguh; Saputro, Sulistyo; Ramli, Murni; Praseptiangga, Danar; Khasanah, Nurul; Marwati, Sri

    2017-01-01

    Valence-shell electron-pair repulsion (VSEPR) theory is conventionally used to predict molecular geometry. However, it is difficult to explore the full implications of this theory by simply drawing chemical structures. Here, we introduce origami modelling as a more accessible approach for exploration of the VSEPR theory. Our technique is simple, readily accessible and inexpensive compared with other sophisticated methods such as computer simulation or commercial three-dimensional modelling kits. This method can be implemented in chemistry education at both the high school and university levels. We discuss the example of a simple molecular structure prediction for ammonia (NH3). Using the origami model, both molecular shape and the scientific justification can be visualized easily. This ‘hands-on’ approach to building molecules will help promote understanding of VSEPR theory.

  8. Understanding valence-shell electron-pair repulsion (VSEPR) theory using origami molecular models

    International Nuclear Information System (INIS)

    Saraswati, Teguh Endah; Saputro, Sulistyo; Ramli, Murni; Praseptiangga, Danar; Khasanah, Nurul; Marwati, Sri

    2017-01-01

    Valence-shell electron-pair repulsion (VSEPR) theory is conventionally used to predict molecular geometry. However, it is difficult to explore the full implications of this theory by simply drawing chemical structures. Here, we introduce origami modelling as a more accessible approach for exploration of the VSEPR theory. Our technique is simple, readily accessible and inexpensive compared with other sophisticated methods such as computer simulation or commercial three-dimensional modelling kits. This method can be implemented in chemistry education at both the high school and university levels. We discuss the example of a simple molecular structure prediction for ammonia (NH_3). Using the origami model, both molecular shape and the scientific justification can be visualized easily. This ‘hands-on’ approach to building molecules will help promote understanding of VSEPR theory. (paper)

  9. Risk communication: a mental models approach

    National Research Council Canada - National Science Library

    Morgan, M. Granger (Millett Granger)

    2002-01-01

    ... information about risks. The procedure uses approaches from risk and decision analysis to identify the most relevant information; it also uses approaches from psychology and communication theory to ensure that its message is understood. This book is written in nontechnical terms, designed to make the approach feasible for anyone willing to try it. It is illustrat...

  10. A bioelectrochemical approach to characterize extracellular electron transfer by Synechocystis sp. PCC6803.

    Directory of Open Access Journals (Sweden)

    Angelo Cereda

    Full Text Available Biophotovoltaic devices employ photosynthetic organisms at the anode of a microbial fuel cell to generate electrical power. Although a range of cyanobacteria and algae have been shown to generate photocurrent in devices of a multitude of architectures, mechanistic understanding of extracellular electron transfer by phototrophs remains minimal. Here we describe a mediatorless bioelectrochemical device to measure the electrogenic output of a planktonically grown cyanobacterium, Synechocystis sp. PCC6803. Light dependent production of current is measured, and its magnitude is shown to scale with microbial cell concentration and light intensity. Bioelectrochemical characterization of a Synechocystis mutant lacking Photosystem II demonstrates conclusively that production of the majority of photocurrent requires a functional water splitting aparatus and electrons are likely ultimately derived from water. This shows the potential of the device to rapidly and quantitatively characterize photocurrent production by genetically modified strains, an approach that can be used in future studies to delineate the mechanisms of cyanobacterial extracellular electron transport.

  11. Electronic Design Automation Using Object Oriented Electronics

    OpenAIRE

    Walid M. Aly; Mohamed S. Abuelnasr

    2010-01-01

    Problem statement: Electronic design automation is the usage of computer technology and software tools for designing integrated electronic system and creating electrical schematics. Approach: An approach is presented for modeling of various electronic and electric devices using object oriented design, aiming on building a library of devices (classes) which can be used for electronic design automation. Results: The presented library was implemented using Java programming language to form an El...

  12. Spectroscopic and magnetic properties of Fe2+ (3d6; S = 2) ions in Fe(NH4)2(SO4)2·6H2O - Modeling zero-field splitting and Zeeman electronic parameters by microscopic spin Hamiltonian approach

    Science.gov (United States)

    Zając, Magdalena; Rudowicz, Czesław; Ohta, Hitoshi; Sakurai, Takahiro

    2018-03-01

    Utilizing the package MSH/VBA, based on the microscopic spin Hamiltonian (MSH) approach, spectroscopic and magnetic properties of Fe2+ (3d6; S = 2) ions at (nearly) orthorhombic sites in Fe(NH4)2(SO4)2·6H2O (FASH) are modeled. The zero-field splitting (ZFS) parameters and the Zeeman electronic (Ze) factors are predicted for wide ranges of values of the microscopic parameters, i.e. the spin-orbit (λ), spin-spin (ρ) coupling constants, and the crystal-field (ligand-field) energy levels (Δi) within the 5D multiplet. This enables to consider the dependence of the ZFS parameters bkq (in the Stevens notation), or the conventional ones (e.g., D and E), and the Zeeman factors gi on λ, ρ, and Δi. By matching the theoretical SH parameters and the experimental ones measured by electron magnetic resonance (EMR), the values of λ, ρ, and Δi best describing Fe2+ ions in FASH are determined. The novel aspect is prediction of the fourth-rank ZFS parameters and the ρ(spin-spin)-related contributions, not considered in previous studies. The higher-order contributions to the second- and fourth-rank ZFSPs are found significant. The MSH predictions provide guidance for high-magnetic field and high-frequency EMR (HMF-EMR) measurements and enable assessment of suitability of FASH for application as high-pressure probes for HMF-EMR studies. The method employed here and the present results may be also useful for other structurally related Fe2+ (S = 2) systems.

  13. A practical approach to temperature effects in dissociative electron attachment cross sections using local complex potential theory

    International Nuclear Information System (INIS)

    Sugioka, Yuji; Takayanagi, Toshiyuki

    2012-01-01

    Highlights: ► Dissociative electron attachment cross sections for polyatomic molecules are calculated by a simple theoretical approach. ► Temperature effects can be reasonably reproduced with the present model. ► All the degrees-of-freedom are taken into account in the present dynamics approach. -- Abstract: We propose a practical computational scheme to obtain temperature dependence of dissociative electron attachment cross sections to polyatomic molecules within a local complex potential theory formalism. First we perform quantum path-integral molecular dynamics simulations on the potential energy surface for the neutral molecule in order to sample initial nuclear configurations as well as momenta. Classical trajectories are subsequently integrated on the potential energy surface for the anionic state and survival probabilities are simultaneously calculated along the obtained trajectories. We have applied this simple scheme to dissociative electron attachment processes to H 2 O and CF 3 Cl, for which several previous studies are available from both the experimental and theoretical sides.

  14. Electronic Processes at Organic−Organic Interfaces: Insight from Modeling and Implications for Opto-electronic Devices †

    KAUST Repository

    Beljonne, David

    2011-02-08

    We report on the recent progress achieved in modeling the electronic processes that take place at interfaces between π-conjugated materials in organic opto-electronic devices. First, we provide a critical overview of the current computational techniques used to assess the morphology of organic: organic heterojunctions; we highlight the compromises that are necessary to handle large systems and multiple time scales while preserving the atomistic details required for subsequent computations of the electronic and optical properties. We then review some recent theoretical advances in describing the ground-state electronic structure at heterojunctions between donor and acceptor materials and highlight the role played by charge-transfer and long-range polarization effects. Finally, we discuss the modeling of the excited-state electronic structure at organic:organic interfaces, which is a key aspect in the understanding of the dynamics of photoinduced electron-transfer processes. © 2010 American Chemical Society.

  15. RENNSH: a novel α-helix identification approach for intermediate resolution electron density maps.

    Science.gov (United States)

    Ma, Lingyu; Reisert, Marco; Burkhardt, Hans

    2012-01-01

    Accurate identification of protein secondary structures is beneficial to understand three-dimensional structures of biological macromolecules. In this paper, a novel refined classification framework is proposed, which treats alpha-helix identification as a machine learning problem by representing each voxel in the density map with its Spherical Harmonic Descriptors (SHD). An energy function is defined to provide statistical analysis of its identification performance, which can be applied to all the α-helix identification approaches. Comparing with other existing α-helix identification methods for intermediate resolution electron density maps, the experimental results demonstrate that our approach gives the best identification accuracy and is more robust to the noise.

  16. A general theoretical model for electron transfer reactions in complex systems.

    Science.gov (United States)

    Amadei, Andrea; Daidone, Isabella; Aschi, Massimiliano

    2012-01-28

    In this paper we present a general theoretical-computational model for treating electron transfer reactions in complex atomic-molecular systems. The underlying idea of the approach, based on unbiased first-principles calculations at the atomistic level, utilizes the definition and the construction of the Diabatic Perturbed states of the involved reactive partners (i.e. the quantum centres in our perturbation approach) as provided by the interaction with their environment, including their mutual interaction. In this way we reconstruct the true Adiabatic states of the reactive partners characterizing the electron transfer process as the fluctuation of the electronic density due to the fluctuating perturbation. Results obtained by using a combination of Molecular Dynamics simulation and the Perturbed Matrix Method on a prototypical intramolecular electron transfer (from 2-(9,9'-dimethyl)fluorene to the 2-naphthalene group separated by a steroidal 5-α-androstane skeleton) well illustrate the accuracy of the method in reproducing both the thermodynamics and the kinetics of the process.

  17. Interatomic electron transport by semiempirical and ab initio tight-binding approaches

    Science.gov (United States)

    Turek, I.; Kudrnovský, J.; Drchal, V.; Szunyogh, L.; Weinberger, P.

    2002-03-01

    A unified approach to interatomic electron transport within Kubo linear-response theory is sketched that is applicable both in semiempirical (matrix-element-based) and ab initio (wave-function-based) tight-binding (TB) techniques. This approach is based on a systematic neglect of the electron motion inside the atomic (Wigner-Seitz) cells leading thus to velocity operators describing pure intersite hopping. This is achieved by using piecewise constant coordinates, i.e., coordinates that are constant inside the cells. The formalism is presented within the simple semiempirical TB method, the TB linear muffin-tin orbital (LMTO) method, and the screened Korringa-Kohn-Rostoker (KKR) method with emphasis on the formal analogy of the derived formulas. The results provide a justification of current assumptions used in semiempirical TB schemes, an assessment of properties of recent TB-LMTO approaches, and an alternative formulation of electron transport within the screened KKR method. The formalism is illustrated by a calculation of residual resistivity of substitutionally disordered fcc Ag-Pd alloys.

  18. Electron-Molecule Col1isions: Quantitative Approaches, and the Legacy of Aaron Temkin

    Science.gov (United States)

    Schneider, B.I.

    2007-01-01

    This article, on electron-molecule collisions, is dedicated to the legacy of my good friend and sometime collaborator, Aaron Temkin on his retirement from the NASA-Goddard Space Flight Center after many years of work at the highest intellectual level in the theoretical treatment of electron-atom and electron-molecule scattering. Aaron's contributions to the manner in which we think about electron-molecule collisions is clear to all of us who have worked in this field. I doubt that the great progress that has occurred in the computational treatment of such complex collision problems could have happened without these contributions. For a brief historical account, see the discussion of Temkin's contribution to electron-molecule scattering in the first article of this volume by Dr. A. K. Bhatia. In this article, I will concentrate on the application of the so called, non-adiabatic R-matrix theory, to vibrational excitation and dissociative attachment, although I will also present some results applying the Linear Algebraic and Kohn-Variational methods to vibrational excitation. As a starting point for almost all computationally effective approaches to electron-molecule collisions, is the fixed nuclei approximation. That is, one recognizes, just as one does with molecular bound states, that there is a separation of electronic(fast) and nuclear(s1ow) degrees of freedom. This separation makes it possible to "freeze" the nuclei in space, calculate the collision parameters for the frozen molecule and then, somehow to add back the vibrations and rotations. The manner in which this is done, depends on the details of the collision problem. It is the work of Aaron and a number of other researchers that has provided the guidance necessary to resolve these issues.

  19. Determination of equilibrium electron temperature and times using an electron swarm model with BOLSIG+ calculated collision frequencies and rate coefficients

    International Nuclear Information System (INIS)

    Pusateri, Elise N.; Morris, Heidi E.; Nelson, Eric M.; Ji, Wei

    2015-01-01

    Electromagnetic pulse (EMP) events produce low-energy conduction electrons from Compton electron or photoelectron ionizations with air. It is important to understand how conduction electrons interact with air in order to accurately predict EMP evolution and propagation. An electron swarm model can be used to monitor the time evolution of conduction electrons in an environment characterized by electric field and pressure. Here a swarm model is developed that is based on the coupled ordinary differential equations (ODEs) described by Higgins et al. (1973), hereinafter HLO. The ODEs characterize the swarm electric field, electron temperature, electron number density, and drift velocity. Important swarm parameters, the momentum transfer collision frequency, energy transfer collision frequency, and ionization rate, are calculated and compared to the previously reported fitted functions given in HLO. These swarm parameters are found using BOLSIG+, a two term Boltzmann solver developed by Hagelaar and Pitchford (2005), which utilizes updated cross sections from the LXcat website created by Pancheshnyi et al. (2012). We validate the swarm model by comparing to experimental effective ionization coefficient data in Dutton (1975) and drift velocity data in Ruiz-Vargas et al. (2010). In addition, we report on electron equilibrium temperatures and times for a uniform electric field of 1 StatV/cm for atmospheric heights from 0 to 40 km. We show that the equilibrium temperature and time are sensitive to the modifications in the collision frequencies and ionization rate based on the updated electron interaction cross sections

  20. Quantitative three-dimensional modeling of zeotile through discrete electron tomography.

    Science.gov (United States)

    Bals, Sara; Batenburg, K Joost; Liang, Duoduo; Lebedev, Oleg; Van Tendeloo, Gustaaf; Aerts, Alexander; Martens, Johan A; Kirschhock, Christine E A

    2009-04-08

    Discrete electron tomography is a new approach for three-dimensional reconstruction of nanoscale objects. The technique exploits prior knowledge of the object to be reconstructed, which results in an improvement of the quality of the reconstructions. Through the combination of conventional transmission electron microscopy and discrete electron tomography with a model-based approach, quantitative structure determination becomes possible. In the present work, this approach is used to unravel the building scheme of Zeotile-4, a silica material with two levels of structural order. The layer sequence of slab-shaped building units could be identified. Successive layers were found to be related by a rotation of 120 degrees, resulting in a hexagonal space group. The Zeotile-4 material is a demonstration of the concept of successive structuring of silica at two levels. At the first level, the colloid chemical properties of Silicalite-1 precursors are exploited to create building units with a slablike geometry. At the second level, the slablike units are tiled using a triblock copolymer to serve as a mesoscale structuring agent.

  1. Modeling Blazar Spectra by Solving an Electron Transport Equation

    Science.gov (United States)

    Lewis, Tiffany; Finke, Justin; Becker, Peter A.

    2018-01-01

    Blazars are luminous active galaxies across the entire electromagnetic spectrum, but the spectral formation mechanisms, especially the particle acceleration, in these sources are not well understood. We develop a new theoretical model for simulating blazar spectra using a self-consistent electron number distribution. Specifically, we solve the particle transport equation considering shock acceleration, adiabatic expansion, stochastic acceleration due to MHD waves, Bohm diffusive particle escape, synchrotron radiation, and Compton radiation, where we implement the full Compton cross-section for seed photons from the accretion disk, the dust torus, and 26 individual broad lines. We used a modified Runge-Kutta method to solve the 2nd order equation, including development of a new mathematical method for normalizing stiff steady-state ordinary differential equations. We show that our self-consistent, transport-based blazar model can qualitatively fit the IR through Fermi g-ray data for 3C 279, with a single-zone, leptonic configuration. We use the solution for the electron distribution to calculate multi-wavelength SED spectra for 3C 279. We calculate the particle and magnetic field energy densities, which suggest that the emitting region is not always in equipartition (a common assumption), but sometimes matter dominated. The stratified broad line region (based on ratios in quasar reverberation mapping, and thus adding no free parameters) improves our estimate of the location of the emitting region, increasing it by ~5x. Our model provides a novel view into the physics at play in blazar jets, especially the relative strength of the shock and stochastic acceleration, where our model is well suited to distinguish between these processes, and we find that the latter tends to dominate.

  2. Tunneling of electrons via rotor–stator molecular interfaces: Combined ab initio and model study

    Energy Technology Data Exchange (ETDEWEB)

    Petreska, Irina, E-mail: irina.petreska@pmf.ukim.mk [Institute of Physics, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University, PO Box 162, 1000 Skopje, Former Yugolav Republic of Macedonia, The (Macedonia, The Former Yugoslav Republic of); Ohanesjan, Vladimir [Institute of Physics, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University, PO Box 162, 1000 Skopje, Former Yugolav Republic of Macedonia, The (Macedonia, The Former Yugoslav Republic of); Pejov, Ljupčo [Institute of Chemistry, Department of Physical Chemistry, Ss. Cyril and Methodius University, Arhimedova 5, P.O. Box 162, 1000 Skopje, Former Yugolav Republic of Macedonia, The (Macedonia, The Former Yugoslav Republic of); Kocarev, Ljupčo [Macedonian Academy of Sciences and Arts, Krste Misirkov 2, PO Box 428, 1000 Skopje, Former Yugolav Republic of Macedonia, The (Macedonia, The Former Yugoslav Republic of); Faculty of Computer Science and Engineering, Ss. Cyril and Methodius University, Skopje, Former Yugolav Republic of Macedonia, The (Macedonia, The Former Yugoslav Republic of)

    2016-07-01

    Tunneling of electrons through rotor–stator anthracene aldehyde molecular interfaces is studied with a combined ab initio and model approach. Molecular electronic structure calculated from first principles is utilized to model different shapes of tunneling barriers. Together with a rectangular barrier, we also consider a sinusoidal shape that captures the effects of the molecular internal structure more realistically. Quasiclassical approach with the Simmons’ formula for current density is implemented. Special attention is paid on conformational dependence of the tunneling current. Our results confirm that the presence of the side aldehyde group enhances the interesting electronic properties of the pure anthracene molecule, making it a bistable system with geometry dependent transport properties. We also investigate the transition voltage and we show that conformation-dependent field emission could be observed in these molecular interfaces at realistically low voltages. The present study accompanies our previous work where we investigated the coherent transport via strongly coupled delocalized orbital by application of Non-equilibrium Green’s Function Formalism.

  3. A new ionospheric electron precipitation module coupled with RAM-SCB within the geospace general circulation model

    Science.gov (United States)

    Yu, Yiqun; Jordanova, Vania K.; Ridley, Aaron J.; Albert, Jay M.; Horne, Richard B.; Jeffery, Christopher A.

    2016-09-01

    Electron precipitation down to the atmosphere due to wave-particle scattering in the magnetosphere contributes significantly to the auroral ionospheric conductivity. In order to obtain the auroral conductivity in global MHD models that are incapable of capturing kinetic physics in the magnetosphere, MHD parameters are often used to estimate electron precipitation flux for the conductivity calculation. Such an MHD approach, however, lacks self-consistency in representing the magnetosphere-ionosphere coupling processes. In this study we improve the coupling processes in global models with a more physical method. We calculate the physics-based electron precipitation from the ring current and map it to the ionospheric altitude for solving the ionospheric electrodynamics. In particular, we use the BATS-R-US (Block Adaptive Tree Scheme-Roe type-Upstream) MHD model coupled with the kinetic ring current model RAM-SCB (Ring current-Atmosphere interaction Model with Self-Consistent Magnetic field (B)) that solves pitch angle-dependent electron distribution functions, to study the global circulation dynamics during the 25-26 January 2013 storm event. Since the electron precipitation loss is mostly governed by wave-particle resonant scattering in the magnetosphere, we further investigate two loss methods of specifying electron precipitation loss associated with wave-particle interactions: (1) using pitch angle diffusion coefficients Dαα(E,α) determined from the quasi-linear theory, with wave spectral and plasma density obtained from statistical observations (named as "diffusion coefficient method") and (2) using electron lifetimes τ(E) independent on pitch angles inferred from the above diffusion coefficients (named as "lifetime method"). We found that both loss methods demonstrate similar temporal evolution of the trapped ring current electrons, indicating that the impact of using different kinds of loss rates is small on the trapped electron population. However, for the

  4. A Discrete Monetary Economic Growth Model with the MIU Approach

    Directory of Open Access Journals (Sweden)

    Wei-Bin Zhang

    2008-01-01

    Full Text Available This paper proposes an alternative approach to economic growth with money. The production side is the same as the Solow model, the Ramsey model, and the Tobin model. But we deal with behavior of consumers differently from the traditional approaches. The model is influenced by the money-in-the-utility (MIU approach in monetary economics. It provides a mechanism of endogenous saving which the Solow model lacks and avoids the assumption of adding up utility over a period of time upon which the Ramsey approach is based.

  5. Mathematical Modelling Approach in Mathematics Education

    Science.gov (United States)

    Arseven, Ayla

    2015-01-01

    The topic of models and modeling has come to be important for science and mathematics education in recent years. The topic of "Modeling" topic is especially important for examinations such as PISA which is conducted at an international level and measures a student's success in mathematics. Mathematical modeling can be defined as using…

  6. A Multivariate Approach to Functional Neuro Modeling

    DEFF Research Database (Denmark)

    Mørch, Niels J.S.

    1998-01-01

    by the application of linear and more flexible, nonlinear microscopic regression models to a real-world dataset. The dependency of model performance, as quantified by generalization error, on model flexibility and training set size is demonstrated, leading to the important realization that no uniformly optimal model......, provides the basis for a generalization theoretical framework relating model performance to model complexity and dataset size. Briefly summarized the major topics discussed in the thesis include: - An introduction of the representation of functional datasets by pairs of neuronal activity patterns...... exists. - Model visualization and interpretation techniques. The simplicity of this task for linear models contrasts the difficulties involved when dealing with nonlinear models. Finally, a visualization technique for nonlinear models is proposed. A single observation emerges from the thesis...

  7. Modeling skin collimation using the electron pencil beam redefinition algorithm.

    Science.gov (United States)

    Chi, Pai-Chun M; Hogstrom, Kenneth R; Starkschall, George; Antolak, John A; Boyd, Robert A

    2005-11-01

    Skin collimation is an important tool for electron beam therapy that is used to minimize the penumbra when treating near critical structures, at extended treatment distances, with bolus, or using arc therapy. It is usually made of lead or lead alloy material that conforms to and is placed on patient surface. Presently, commercially available treatment-planning systems lack the ability to model skin collimation and to accurately calculate dose in its presence. The purpose of the present work was to evaluate the use of the pencil beam redefinition algorithm (PBRA) in calculating dose in the presence of skin collimation. Skin collimation was incorporated into the PBRA by terminating the transport of electrons once they enter the skin collimator. Both fixed- and arced-beam dose calculations for arced-beam geometries were evaluated by comparing them with measured dose distributions for 10- and 15-MeV beams. Fixed-beam dose distributions were measured in water at 88-cm source-to-surface distance with an air gap of 32 cm. The 6 x 20-cm2 field (dimensions projected to isocenter) had a 10-mm thick lead collimator placed on the surface of the water with its edge 5 cm inside the field's edge located at +10 cm. Arced-beam dose distributions were measured in a 13.5-cm radius polystyrene circular phantom. The beam was arced 90 degrees (-45 degrees to +45 degrees), and 10-mm thick lead collimation was placed at +/- 30 degrees. For the fixed beam at 10 MeV, the PBRA- calculated dose agreed with measured dose to within 2.0-mm distance to agreement (DTA) in the regions of high-dose gradient and 2.0% in regions of low dose gradient. At 15 MeV, the PBRA agreed to within a 2.0-mm DTA in the regions of high-dose gradient; however, the PBRA underestimated the dose by as much as 5.3% over small regions at depths less than 2 cm because it did not model electrons scattered from the edge of the skin collimation. For arced beams at 10 MeV, the agreement was 1-mm DTA in the high-dose gradient

  8. Accurate Electron Affinities and Orbital Energies of Anions from a Nonempirically Tuned Range-Separated Density Functional Theory Approach.

    Science.gov (United States)

    Anderson, Lindsey N; Oviedo, M Belén; Wong, Bryan M

    2017-04-11

    The treatment of atomic anions with Kohn-Sham density functional theory (DFT) has long been controversial because the highest occupied molecular orbital (HOMO) energy, E HOMO , is often calculated to be positive with most approximate density functionals. We assess the accuracy of orbital energies and electron affinities for all three rows of elements in the periodic table (H-Ar) using a variety of theoretical approaches and customized basis sets. Among all of the theoretical methods studied here, we find that a nonempirically tuned range-separated approach (constructed to satisfy DFT-Koopmans' theorem for the anionic electron system) provides the best accuracy for a variety of basis sets, even for small basis sets where most functionals typically fail. Previous approaches to solve this conundrum of positive E HOMO values have utilized non-self-consistent methods; however, electronic properties, such as electronic couplings/gradients (which require a self-consistent potential and energy), become ill-defined with these approaches. In contrast, the nonempirically tuned range-separated procedure used here yields well-defined electronic couplings/gradients and correct E HOMO values because both the potential and resulting electronic energy are computed self-consistently. Orbital energies and electron affinities are further analyzed in the context of the electronic energy as a function of electronic number (including fractional numbers of electrons) to provide a stringent assessment of self-interaction errors for these complex anion systems.

  9. Design of laser-generated shockwave experiments. An approach using analytic models

    International Nuclear Information System (INIS)

    Lee, Y.T.; Trainor, R.J.

    1980-01-01

    Two of the target-physics phenomena which must be understood before a clean experiment can be confidently performed are preheating due to suprathermal electrons and shock decay due to a shock-rarefaction interaction. Simple analytic models are described for these two processes and the predictions of these models are compared with those of the LASNEX fluid physics code. We have approached this work not with the view of surpassing or even approaching the reliability of the code calculations, but rather with the aim of providing simple models which may be used for quick parameter-sensitivity evaluations, while providing physical insight into the problems

  10. A correlative optical microscopy and scanning electron microscopy approach to locating nanoparticles in brain tumors.

    Science.gov (United States)

    Kempen, Paul J; Kircher, Moritz F; de la Zerda, Adam; Zavaleta, Cristina L; Jokerst, Jesse V; Mellinghoff, Ingo K; Gambhir, Sanjiv S; Sinclair, Robert

    2015-01-01

    The growing use of nanoparticles in biomedical applications, including cancer diagnosis and treatment, demands the capability to exactly locate them within complex biological systems. In this work a correlative optical and scanning electron microscopy technique was developed to locate and observe multi-modal gold core nanoparticle accumulation in brain tumor models. Entire brain sections from mice containing orthotopic brain tumors injected intravenously with nanoparticles were imaged using both optical microscopy to identify the brain tumor, and scanning electron microscopy to identify the individual nanoparticles. Gold-based nanoparticles were readily identified in the scanning electron microscope using backscattered electron imaging as bright spots against a darker background. This information was then correlated to determine the exact location of the nanoparticles within the brain tissue. The nanoparticles were located only in areas that contained tumor cells, and not in the surrounding healthy brain tissue. This correlative technique provides a powerful method to relate the macro- and micro-scale features visible in light microscopy with the nanoscale features resolvable in scanning electron microscopy. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Modeling of the response under radiation of electronic dosemeters

    International Nuclear Information System (INIS)

    Menard, S.

    2003-01-01

    The simulation with with calculation codes the interactions and the transport of primary and secondary radiations in the detectors allows to reduce the number of developed prototypes and the number of experiments under radiation. The simulation makes possible the determination of the response of the instrument for exposure configurations more extended that these ones of references radiations produced in laboratories. The M.C.N.P.X. allows to transport, over the photons, electrons and neutrons, the charged particles heavier than the electrons and to simulate the radiation - matter interactions for a certain number of particles. The present paper aims to present the interest of the use of the M.C.N.P.X. code in the study, research and evaluation phases of the instrumentation necessary to the dosimetry monitoring. To do that the presentation gives the results of the modeling of a prototype of a equivalent tissue proportional counter (C.P.E.T.) and of the C.R.A.M.A.L. ( radiation protection apparatus marketed by the Eurisys Mesures society). (N.C.)

  12. A Model of Electron-Positron Pair Formation

    Directory of Open Access Journals (Sweden)

    Lehnert B.

    2008-01-01

    Full Text Available The elementary electron-positron pair formation process is consideredin terms of a revised quantum electrodynamic theory, with specialattention to the conservation of energy, spin, and electric charge.The theory leads to a wave-packet photon model of narrow line widthand needle-radiation properties, not being available from conventionalquantum electrodynamics which is based on Maxwell's equations. Themodel appears to be consistent with the observed pair productionprocess, in which the created electron and positron form two raysthat start within a very small region and have original directionsalong the path of the incoming photon. Conservation of angular momentum requires the photon to possess a spin, as given by the present theory but not by the conventional one. The nonzero electric field divergence further gives rise to a local intrinsic electric charge density within the photon body, whereas there is a vanishing total charge of the latter. This may explain the observed fact that the photon decays on account of the impact from an external electric field. Such a behaviour should not become possible for a photon having zero local electric charge density.

  13. A proposed model of e-trust for electronic banking

    Directory of Open Access Journals (Sweden)

    Neda Yousefi

    2015-11-01

    Full Text Available Customer’s trust is the most important and one of the key factors of success in e-commerce. However, trust is the essential aspects of e-banking adoption and the main element for building long-term relationships with the bank's customers. So the purpose of this research is to investigate the factors influencing on customer′s trust in e-banking services and prioritize them. Therefore, designed questionnaire was distributed among 177 electronic service customers in number of banks in the city of Karaj, Iran. Likert quintuplet scales were used to measure the variables. After collecting the questionnaires, the data were analyzed by structural equation modeling (by using LISREL 8.5. The results revealed that quality of electronic services such as ease of use, privacy and security, individual characteristics of customers such as disposition to trust and features of bank such as reputation, size and dependence on government, have had the greatest effect on customer′s trust in e-banking services.

  14. Model of e-learning with electronic educational resources of new generation

    Directory of Open Access Journals (Sweden)

    A. V. Loban

    2017-01-01

    Full Text Available Purpose of the article: improving of scientific and methodical base of the theory of the е-learning of variability. Methods used: conceptual and logical modeling of the е-learning of variability process with electronic educational resource of new generation and system analysis of the interconnection of the studied subject area, methods, didactics approaches and information and communication technologies means. Results: the formalization complex model of the е-learning of variability with electronic educational resource of new generation is developed, conditionally decomposed into three basic components: the formalization model of the course in the form of the thesaurusclassifier (“Author of e-resource”, the model of learning as management (“Coordination. Consultation. Control”, the learning model with the thesaurus-classifier (“Student”. Model “Author of e-resource” allows the student to achieve completeness, high degree of didactic elaboration and structuring of the studied material in triples of variants: modules of education information, practical task and control tasks; the result of the student’s (author’s of e-resource activity is the thesaurus-classifier. Model of learning as management is based on the principle of personal orientation of learning in computer environment and determines the logic of interaction between the lecturer and the student when determining the triple of variants individually for each student; organization of a dialogue between the lecturer and the student for consulting purposes; personal control of the student’s success (report generation and iterative search for the concept of the class assignment in the thesaurus-classifier before acquiring the required level of training. Model “Student” makes it possible to concretize the learning tasks in relation to the personality of the student and to the training level achieved; the assumption of the lecturer about the level of training of a

  15. Uncertainty in biology a computational modeling approach

    CERN Document Server

    Gomez-Cabrero, David

    2016-01-01

    Computational modeling of biomedical processes is gaining more and more weight in the current research into the etiology of biomedical problems and potential treatment strategies.  Computational modeling allows to reduce, refine and replace animal experimentation as well as to translate findings obtained in these experiments to the human background. However these biomedical problems are inherently complex with a myriad of influencing factors, which strongly complicates the model building and validation process.  This book wants to address four main issues related to the building and validation of computational models of biomedical processes: Modeling establishment under uncertainty Model selection and parameter fitting Sensitivity analysis and model adaptation Model predictions under uncertainty In each of the abovementioned areas, the book discusses a number of key-techniques by means of a general theoretical description followed by one or more practical examples.  This book is intended for graduate stude...

  16. Relaxed memory models: an operational approach

    OpenAIRE

    Boudol , Gérard; Petri , Gustavo

    2009-01-01

    International audience; Memory models define an interface between programs written in some language and their implementation, determining which behaviour the memory (and thus a program) is allowed to have in a given model. A minimal guarantee memory models should provide to the programmer is that well-synchronized, that is, data-race free code has a standard semantics. Traditionally, memory models are defined axiomatically, setting constraints on the order in which memory operations are allow...

  17. Electronic design automation of analog ICs combining gradient models with multi-objective evolutionary algorithms

    CERN Document Server

    Rocha, Frederico AE; Lourenço, Nuno CC; Horta, Nuno CG

    2013-01-01

    This book applies to the scientific area of electronic design automation (EDA) and addresses the automatic sizing of analog integrated circuits (ICs). Particularly, this book presents an approach to enhance a state-of-the-art layout-aware circuit-level optimizer (GENOM-POF), by embedding statistical knowledge from an automatically generated gradient model into the multi-objective multi-constraint optimization kernel based on the NSGA-II algorithm. The results showed allow the designer to explore the different trade-offs of the solution space, both through the achieved device sizes, or the resp

  18. The Dismantling of the Japanese Model in Consumer Electronics

    DEFF Research Database (Denmark)

    Frøslev Christensen, Jens; Holm Olesen, Michael; Kjær, Jonas

    -based innovation, the current transformation ofsound amplification from conventional to digital amplifiers. We study the early formation of thisnew technology as especially reflected in the particularly dynamic cluster of innovation inDenmark and extend the analysis to the global strategizing around this new......This paper addresses an issue of great importance for the future organization of the consumerelectronics industry: the "battle" of control over component-based digitization. We are now witnessing the dismantling of the Japanese Model that has prevailed in consumer electronicsover the past 30 years....... Specialized and large-scale component suppliers have taken the lead inmost component-based innovations and have obtained increasingly powerful positions in thevalue chain of consumer electronics. This paper provides an in-depth study of the strategic andstructural ramifications of one such component...

  19. Nonlinear electromagnetic gyrokinetic particle simulations with the electron hybrid model

    Science.gov (United States)

    Nishimura, Y.; Lin, Z.; Chen, L.; Hahm, T.; Wang, W.; Lee, W.

    2006-10-01

    The electromagnetic model with fluid electrons is successfully implemented into the global gyrokinetic code GTC. In the ideal MHD limit, shear Alfven wave oscillation and continuum damping is demonstrated. Nonlinear electromagnetic simulation is further pursued in the presence of finite ηi. Turbulence transport in the AITG unstable β regime is studied. This work is supported by Department of Energy (DOE) Grant DE-FG02-03ER54724, Cooperative Agreement No. DE-FC02-04ER54796 (UCI), DOE Contract No. DE-AC02-76CH03073 (PPPL), and in part by SciDAC Center for Gyrokinetic Particle Simulation of Turbulent Transport in Burning Plasmas. Z. Lin, et al., Science 281, 1835 (1998). F. Zonca and L. Chen, Plasma Phys. Controlled Fusion 30, 2240 (1998); G. Zhao and L. Chen, Phys. Plasmas 9, 861 (2002).

  20. Comprehensive Power Losses Model for Electronic Power Transformer

    DEFF Research Database (Denmark)

    Yue, Quanyou; Li, Canbing; Cao, Yijia

    2018-01-01

    and considering the impact of the non-unity power factor and the three-phase unbalanced current, the overall power losses in the distribution network when using the EPT to replace the conventional transformer is analyzed, and the conditions in which the application of the EPT can cause less power losses...... reduced power losses in the distribution network require a comprehensive consideration when comparing the power losses of theEPT and conventional transformer. In this paper, a comprehensive power losses analysis model for the EPT in distribution networks is proposed. By analyzing the EPT self-losses......The electronic power transformer (EPT) has highe rpower losses than the conventional transformer. However, the EPT can correct the power factor, compensate the unbalanced current and reduce the line power losses in the distribution network.Therefore, the higher losses of the EPT and the consequent...

  1. Comprehensive Power Losses Model for Electronic Power Transformer

    DEFF Research Database (Denmark)

    Yue, Quanyou; Li, Canbing; Cao, Yijia

    2018-01-01

    The electronic power transformer (EPT) has highe rpower losses than the conventional transformer. However, the EPT can correct the power factor, compensate the unbalanced current and reduce the line power losses in the distribution network.Therefore, the higher losses of the EPT and the consequent......-losses and considering the impact of the non-unity power factor and the three-phase unbalanced current, the overall power losses in the distribution network when using the EPT to replace the conventional transformer is analyzed, and the conditions in which the application of the EPT can cause less power losses...... reduced power losses in the distribution network require a comprehensive consideration when comparing the power losses of theEPT and conventional transformer. In this paper, a comprehensive power losses analysis model for the EPT in distribution networks is proposed. By analyzing the EPT self...

  2. Numerical modelling approach for mine backfill

    Indian Academy of Sciences (India)

    ... of mine backfill material needs special attention as the numerical model must behave realistically and in accordance with the site conditions. This paper discusses a numerical modelling strategy for modelling mine backfill material. Themodelling strategy is studied using a case study mine from Canadian mining industry.

  3. Theoretical study of molecular vibrations in electron momentum spectroscopy experiments on furan: An analytical versus a molecular dynamical approach

    Energy Technology Data Exchange (ETDEWEB)

    Morini, Filippo; Deleuze, Michael S., E-mail: michael.deleuze@uhasselt.be [Center of Molecular and Materials Modelling, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek (Belgium); Watanabe, Noboru; Takahashi, Masahiko [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan)

    2015-03-07

    The influence of thermally induced nuclear dynamics (molecular vibrations) in the initial electronic ground state on the valence orbital momentum profiles of furan has been theoretically investigated using two different approaches. The first of these approaches employs the principles of Born-Oppenheimer molecular dynamics, whereas the so-called harmonic analytical quantum mechanical approach resorts to an analytical decomposition of contributions arising from quantized harmonic vibrational eigenstates. In spite of their intrinsic differences, the two approaches enable consistent insights into the electron momentum distributions inferred from new measurements employing electron momentum spectroscopy and an electron impact energy of 1.2 keV. Both approaches point out in particular an appreciable influence of a few specific molecular vibrations of A{sub 1} symmetry on the 9a{sub 1} momentum profile, which can be unravelled from considerations on the symmetry characteristics of orbitals and their energy spacing.

  4. Patient Electronic Health Data–Driven Approach to Clinical Decision Support

    Science.gov (United States)

    Mane, Ketan K.; Bizon, Chris; Owen, Phillips; Gersing, Ken; Mostafa, Javed; Schmitt, Charles

    2011-01-01

    Abstract  This article presents a novel visual analytics (VA)‐based clinical decision support (CDS) tool prototype that was designed as a collaborative work between Renaissance Computing Institute and Duke University. Using Major Depressive Disorder data from MindLinc electronic health record system at Duke, the CDS tool shows an approach to leverage data from comparative population (patients with similar medical profile) to enhance a clinicians’ decision making process at the point of care. The initial work is being extended in collaboration with the University of North Carolina CTSA to address the key challenges of CDS, as well as to show the use of VA to derive insight from large volumes of Electronic Health Record patient data. Clin Trans Sci 2011; Volume 4: 369–371 PMID:22029811

  5. NEW APPROACHES IN TEXTUAL EDITING. A SELECTION OF ELECTRONIC EDITIONS UNDER ANALYSIS

    Directory of Open Access Journals (Sweden)

    Isabel De la Cruz

    2005-12-01

    Full Text Available In the present article, we make an approach to the world of digital editions available in electronic format. Using as a starting point Professor González Fernández-Corugedo's classification of some of the best web pages related to the topic (available at http://www.uniovi.es/HELL/Hyptxed.html we have examined the design and contents of some sites that deal with texts mainly in Old and Middle English. The readers are offered an outline of what they are expected to find in every page, highlighting their main virtues and shortcomings. As a result of the analysis of al1 these pages we are ready to propose certain steps necessary in the elaboration of a 'good' electronic edition.

  6. Thermal expansion model for multiphase electronic packaging materials

    International Nuclear Information System (INIS)

    Allred, B.E.; Warren, W.E.

    1991-01-01

    Control of thermal expansion is often necessary in the design and selection of electronic packages. In some instances, it is desirable to have a coefficient of thermal expansion intermediate between values readily attainable with single or two phase materials. The addition of a third phase in the form of fillers, whiskers, or fibers can be used to attain intermediate expansions. To help design the thermal expansion of multiphase materials for specific applications, a closed form model has been developed that accurately predicts the effective elastic properties of isotropic filled materials and transversely isotropic lamina. Properties of filled matrix materials are used as inputs to the lamina model to obtain the composite elastic properties as a function of the volume fraction of each phase. Hybrid composites with two or more fiber types are easily handled with this model. This paper reports that results for glass, quartz, and Kevlar fibers with beta-eucryptite filled polymer matrices show good agreement with experimental results for X, Y, and Z thermal expansion coefficients

  7. Reduction of electronic delay in active noise control systems--a multirate signal processing approach.

    Science.gov (United States)

    Bai, Mingsian R; Lin, Yuanpei; Lai, Jienwen

    2002-02-01

    Electronic delay has been a critical problem in active noise control (ANC) systems. This is true whether a feedforward structure or a feedback structure is adopted. In particular, excessive delays would create a causality problem in a feedforward ANC system of a finite-length duct. This paper suggests a multirate signal-processing approach for minimizing the electronic delay in the control loop. In this approach, digital controllers are required in decimation and interpolation of discrete-time signals. The computation efficiency is further enhanced by a polyphase method, where the phases of low-pass finite impulse response (FIR) filters must be carefully designed to avoid unnecessary delays. Frequency domain optimization procedures based on H1, H2, and Hinfinity norms, respectively, are utilized in the FIR filter design. The proposed method was implemented by using a floating-point digital signal processor. Experimental results showed that the multirate approach remains effective for suppressing a broadband (200-600 Hz) noise in a duct with a minimum upstream measurement microphone placement of 20 cm.

  8. Comparing Fourier optics and contrast transfer function modeling of image formation in low energy electron microscopy.

    Science.gov (United States)

    Yu, K M; Locatelli, A; Altman, M S

    2017-12-01

    A theoretical understanding of image formation in cathode lens microscopy can facilitate image interpretation. We compare Fourier Optics (FO) and Contrast Transfer Function (CTF) approaches that were recently adapted from other realms of microscopy to model image formation in low energy electron microscopy (LEEM). Although these two approaches incorporate imaging errors from several sources similarly, they differ in the way that the image intensity is calculated. The simplification that is used in the CTF calculation advantageously leads to its computational efficiency. However, we find that lens aberrations, and spatial and temporal coherence may affect the validity of the CTF approach to model LEEM image formation under certain conditions. In particular, these effects depend strongly on the nature of the object being imaged and also become more pronounced with increasing defocus. While the use of the CTF approach appears to be justified for objects that are routinely imaged with LEEM, comparison of theory to experimental observations of a focal image series for rippled, suspended graphene reveals one example where FO works, but CTF does not. This work alerts us to potential pitfalls and guides the effective use of FO and CTF approaches. It also lays the foundation for quantitative image evaluation using these methods. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. A new approach in the development of quality management systems for (micro)electronics

    Science.gov (United States)

    Bacivarov, Ioan C.; Bacivarov, Angelica; Gherghina, Cǎtǎlina

    2016-12-01

    This paper presents the new approach in the analysis of the Quality Management Systems (QMS) of companies, based on the revised standard ISO 9001:2015. In the first part of the paper, QMS based on ISO 9001 certification are introduced; the changes and the updates proposed for the new version of ISO 9001:2015 are critically analyzed, based on the documents elaborated by ISO/TC 176. The approach based on ISO 9001:2015 could be considered as "beginning of a new era in development of quality management systems". A comparison between the between the "old" standard ISO 9001:2008 and the "new" standard ISO 9001:2015 is made. In the second part of the paper, steps to be followed in a company to implement this new standard are presented. A peculiar attention is given to the new concept of risk-based thinking in order to support and improve application of the process based approach. The authors conclude that, by considering risk throughout the organization the likelihood of achieving stated objectives is improved, output is more consistent and customers can be confident that they will receive the expected results. Finally, the benefits of the new approach in the development of quality management systems are outlined, as well as how they are reflected in the management of companies in general and those in electronics field, in particular. As demonstrated in this paper, well understood and properly applied, the new approach based on the revised standard ISO9001:2015 could offer a better quality management for companies operating in electronics and beyond.

  10. A New Approach in Teaching Power Electronics Control of Electrical Drives using Real-Time

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Bech, Michael Møller; Blaabjerg, Frede

    2000-01-01

    A new approach in teaching power electronics and electrical drives is achieved at the Flexible Drives System Laboratory (FDSL) from Aalborg University by using the new Total Development Environment (TDE) concept that allows a full visual block-oriented programming of dynamic real-time systems to ...... to be done using the Matlab/Simulink environment. Basics in Electrical Drives and Advanced Control of PWM Inverter Fed Induction Machines courses are succesfully using the new facility and an increased student enrollment is expected in the next coming years....

  11. Stepwise approach to establishing multiple outreach laboratory information system-electronic medical record interfaces.

    Science.gov (United States)

    Pantanowitz, Liron; Labranche, Wayne; Lareau, William

    2010-05-26

    Clinical laboratory outreach business is changing as more physician practices adopt an electronic medical record (EMR). Physician connectivity with the laboratory information system (LIS) is consequently becoming more important. However, there are no reports available to assist the informatician with establishing and maintaining outreach LIS-EMR connectivity. A four-stage scheme is presented that was successfully employed to establish unidirectional and bidirectional interfaces with multiple physician EMRs. This approach involves planning (step 1), followed by interface building (step 2) with subsequent testing (step 3), and finally ongoing maintenance (step 4). The role of organized project management, software as a service (SAAS), and alternate solutions for outreach connectivity are discussed.

  12. SXR Continuum Radiation Transmitted Through Metallic Filters: An Analytical Approach To Fast Electron Temperature Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Delgado-Aparicio, L.; Tritz, K.; Kramer, T.; Stutman, D.; Finkentha, M.; Hill, K.; Bitter, M.

    2010-08-26

    A new set of analytic formulae describes the transmission of soft X-ray (SXR) continuum radiation through a metallic foil for its application to fast electron temperature measurements in fusion plasmas. This novel approach shows good agreement with numerical calculations over a wide range of plasma temperatures in contrast with the solutions obtained when using a transmission approximated by a single-Heaviside function [S. von Goeler, Rev. Sci. Instrum., 20, 599, (1999)]. The new analytic formulae can improve the interpretation of the experimental results and thus contribute in obtaining fast teperature measurements in between intermittent Thomson Scattering data.

  13. Models Portability: Some Considerations about Transdisciplinary Approaches

    Science.gov (United States)

    Giuliani, Alessandro

    Some critical issues about the relative portability of models and solutions across disciplinary barriers are discussed. The risks linked to the use of models and theories coming from different disciplines are evidentiated with a particular emphasis on biology. A metaphorical use of conceptual tools coming from other fields is suggested, together with the unescapable need to judge about the relative merits of a model on the basis of the amount of facts relative to the particular domain of application it explains. Some examples of metaphorical modeling coming from biochemistry and psychobiology are briefly discussed in order to clarify the above positions.

  14. Nonlinear Modeling of the PEMFC Based On NNARX Approach

    OpenAIRE

    Shan-Jen Cheng; Te-Jen Chang; Kuang-Hsiung Tan; Shou-Ling Kuo

    2015-01-01

    Polymer Electrolyte Membrane Fuel Cell (PEMFC) is such a time-vary nonlinear dynamic system. The traditional linear modeling approach is hard to estimate structure correctly of PEMFC system. From this reason, this paper presents a nonlinear modeling of the PEMFC using Neural Network Auto-regressive model with eXogenous inputs (NNARX) approach. The multilayer perception (MLP) network is applied to evaluate the structure of the NNARX model of PEMFC. The validity and accurac...

  15. A visual approach for modeling spatiotemporal relations

    NARCIS (Netherlands)

    R.L. Guimarães (Rodrigo); C.S.S. Neto; L.F.G. Soares

    2008-01-01

    htmlabstractTextual programming languages have proven to be difficult to learn and to use effectively for many people. For this sake, visual tools can be useful to abstract the complexity of such textual languages, minimizing the specification efforts. In this paper we present a visual approach for

  16. DIVERSE APPROACHES TO MODELLING THE ASSIMILATIVE ...

    African Journals Online (AJOL)

    This study evaluated the assimilative capacity of Ikpoba River using different approaches namely: homogeneous differential equation, ANOVA/Duncan Multiple rage test, first and second order differential equations, correlation analysis, Eigen values and eigenvectors, multiple linear regression, bootstrapping and far-field ...

  17. Electronic pairing mechanism due to band modification in a two-band model: Tc evaluation

    International Nuclear Information System (INIS)

    Mizia, J.; Gorski, G.; Traa, M.R.M.J.

    1997-01-01

    Following the electronic model developed by us previously (Mizia and Romanowski, Mizia) we estimate the superconducting transition temperature in a simple electronic two-band model for materials characterized by a broad superconducting band and a narrow level within the same energy range. A large electron deformation coupling constant and large electron correlation effects are assumed. It is shown that high-temperature superconductivity is entirely possible within a range of reasonable electronic parameters. This model does not assume any artificial interactions to obtain a negative pairing potential. Instead, the negative part of the electronic interaction potential comes from the modification of the electron dispersion relation with growing number of superconducting pairs. Such a modification is possible in soft electronic systems, i.e. in systems partial to band modification due to large internal stresses, strong electronic correlation effects and broad band narrow level charge transfer during the superconducting transition. (orig.)

  18. Electronic transport in graphene-based structures: An effective cross-section approach

    DEFF Research Database (Denmark)

    Uppstu, Andreas; Saloriutta, Karri; Harju, Ari

    2012-01-01

    We show that transport in low-dimensional carbon structures with finite concentrations of scatterers can be modeled by utilizing scaling theory and effective cross sections. Our results are based on large-scale numerical simulations of carbon nanotubes and graphene nanoribbons, using a tight......-binding model with parameters obtained from first-principles electronic structure calculations. As shown by a comprehensive statistical analysis, the scattering cross sections can be used to estimate the conductance of a quasi-one-dimensional system both in the Ohmic and localized regimes. They can be computed...

  19. Improving high-altitude emp modeling capabilities by using a non-equilibrium electron swarm model to monitor conduction electron evolution

    Science.gov (United States)

    Pusateri, Elise Noel

    An Electromagnetic Pulse (EMP) can severely disrupt the use of electronic devices in its path causing a significant amount of infrastructural damage. EMP can also cause breakdown of the surrounding atmosphere during lightning discharges. This makes modeling EMP phenomenon an important research effort in many military and atmospheric physics applications. EMP events include high-energy Compton electrons or photoelectrons that ionize air and produce low energy conduction electrons. A sufficient number of conduction electrons will damp or alter the EMP through conduction current. Therefore, it is important to understand how conduction electrons interact with air in order to accurately predict the EMP evolution and propagation in the air. It is common for EMP simulation codes to use an equilibrium ohmic model for computing the conduction current. Equilibrium ohmic models assume the conduction electrons are always in equilibrium with the local instantaneous electric field, i.e. for a specific EMP electric field, the conduction electrons instantaneously reach steady state without a transient process. An equilibrium model will work well if the electrons have time to reach their equilibrium distribution with respect to the rise time or duration of the EMP. If the time to reach equilibrium is comparable or longer than the rise time or duration of the EMP then the equilibrium model would not accurately predict the conduction current necessary for the EMP simulation. This is because transport coefficients used in the conduction current calculation will be found based on equilibrium reactions rates which may differ significantly from their non-equilibrium values. We see this deficiency in Los Alamos National Laboratory's EMP code, CHAP-LA (Compton High Altitude Pulse-Los Alamos), when modeling certain EMP scenarios at high altitudes, such as upward EMP, where the ionization rate by secondary electrons is over predicted by the equilibrium model, causing the EMP to short

  20. Comparison of two novel approaches to model fibre reinforced concrete

    NARCIS (Netherlands)

    Radtke, F.K.F.; Simone, A.; Sluys, L.J.

    2009-01-01

    We present two approaches to model fibre reinforced concrete. In both approaches, discrete fibre distributions and the behaviour of the fibre-matrix interface are explicitly considered. One approach employs the reaction forces from fibre to matrix while the other is based on the partition of unity

  1. Modeling Approaches for Describing Microbial Population Heterogeneity

    DEFF Research Database (Denmark)

    Lencastre Fernandes, Rita

    in a computational (CFD) fluid dynamic model. The anaerobic Growth of a budding yeast population in a continuously run microbioreactor was used as example. The proposed integrated model describes the fluid flow, the local cell size and cell cycle position distributions, as well as the local concentrations of glucose...

  2. A simplified approach to feedwater train modeling

    International Nuclear Information System (INIS)

    Ollat, X.; Smoak, R.A.

    1990-01-01

    This paper presents a method to simplify feedwater train models for power plants. A simple set of algebraic equations, based on mass and energy balances, is developed to replace complex representations of the components under certain assumptions. The method was tested and used to model the low pressure heaters of the Sequoyah Nuclear Plant in a larger simulation

  3. Multi-timescale modelling for the loading behaviours of power electronics converter

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede

    2015-01-01

    -seconds to years, thereby the complete loading conditions of power device are still challenge to be predicted by the existing models, which normally have to be restricted at certain time ranges. As a result, a more advanced modelling concept is proposed in this paper, which separates the converter system......The thermal dynamics of power device, referred as “thermal cycling”, are closely related to the reliability as well as the cost of the power electronics converter. However, the device loading is disturbed by many factors of the converter system which present at various times-constants from micro......-timescales modelling concept and approaches, more complete loading information of power device can be mapped based on the mission profiles of converter, thus it is very helpful for better prediction of converter lifetime and more cost-effective design of the cooling system....

  4. A Study on Technology Architecture and Serving Approaches of Electronic Government System

    Science.gov (United States)

    Liu, Chunnian; Huang, Yiyun; Pan, Qin

    As E-government becomes a very active research area, a lot of solutions to solve citizens' needs are being deployed. This paper provides technology architecture of E-government system and approaches of service in Public Administrations. The proposed electronic system addresses the basic E-government requirements of user friendliness, security, interoperability, transparency and effectiveness in the communication between small and medium sized public organizations and their citizens, businesses and other public organizations. The paper has provided several serving approaches of E-government, which includes SOA, web service, mobile E-government, public library and every has its own characteristics and application scenes. Still, there are a number of E-government issues for further research on organization structure change, including research methodology, data collection analysis, etc.

  5. Analytical approach to phonons and electron-phonon interactions in single-walled zigzag carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Kandemir, B S; Keskin, M [Department of Physics, Faculty of Sciences, Ankara University, 06100 Tandogan, Ankara (Turkey)

    2008-08-13

    In this paper, exact analytical expressions for the entire phonon spectra in single-walled carbon nanotubes with zigzag geometry are presented by using a new approach, originally developed by Kandemir and Altanhan. This approach is based on the concept of construction of a classical lattice Hamiltonian of single-walled carbon nanotubes, wherein the nearest and next nearest neighbor and bond bending interactions are all included, then its quantization and finally diagonalization of the resulting second quantized Hamiltonian. Furthermore, within this context, explicit analytical expressions for the relevant electron-phonon interaction coefficients are also investigated for single-walled carbon nanotubes having this geometry, by the phonon modulation of the hopping interaction.

  6. Analytical approach to phonons and electron-phonon interactions in single-walled zigzag carbon nanotubes

    International Nuclear Information System (INIS)

    Kandemir, B S; Keskin, M

    2008-01-01

    In this paper, exact analytical expressions for the entire phonon spectra in single-walled carbon nanotubes with zigzag geometry are presented by using a new approach, originally developed by Kandemir and Altanhan. This approach is based on the concept of construction of a classical lattice Hamiltonian of single-walled carbon nanotubes, wherein the nearest and next nearest neighbor and bond bending interactions are all included, then its quantization and finally diagonalization of the resulting second quantized Hamiltonian. Furthermore, within this context, explicit analytical expressions for the relevant electron-phonon interaction coefficients are also investigated for single-walled carbon nanotubes having this geometry, by the phonon modulation of the hopping interaction

  7. Lumped Parameter Modeling for Rapid Vibration Response Prototyping and Test Correlation for Electronic Units

    Science.gov (United States)

    Van Dyke, Michael B.

    2013-01-01

    Present preliminary work using lumped parameter models to approximate dynamic response of electronic units to random vibration; Derive a general N-DOF model for application to electronic units; Illustrate parametric influence of model parameters; Implication of coupled dynamics for unit/board design; Demonstrate use of model to infer printed wiring board (PWB) dynamics from external chassis test measurement.

  8. A Massless-Point-Charge Model for the Electron

    Directory of Open Access Journals (Sweden)

    Daywitt W. C.

    2010-04-01

    Full Text Available "It is rather remarkable that the modern concept of electrodynamics is not quite 100 years old and yet still does not rest firmly upon uniformly accepted theoretical foundations. Maxwell's theory of the electromagnetic field is firmly ensconced in modern physics, to be sure, but the details of how charged particles are to be coupled to this field remain somewhat uncertain, despite the enormous advances in quantum electrodynamics over the past 45 years. Our theories remain mathematically ill-posed and mired in conceptual ambiguities which quantum mechanics has only moved to another arena rather than resolve. Fundamentally, we still do not understand just what is a charged particle" (Grandy W.T. Jr. Relativistic quantum mechanics of leptons and fields. Kluwer Academic Publishers, Dordrecht-London, 1991, p.367. As a partial answer to the preceeding quote, this paper presents a new model for the electron that combines the seminal work of Puthoff with the theory of the Planck vacuum (PV, the basic idea for the model following from Puthoff with the PV theory adding some important details.

  9. 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.

  10. Electron beam lithographic modeling assisted by artificial intelligence technology

    Science.gov (United States)

    Nakayamada, Noriaki; Nishimura, Rieko; Miura, Satoru; Nomura, Haruyuki; Kamikubo, Takashi

    2017-07-01

    We propose a new concept of tuning a point-spread function (a "kernel" function) in the modeling of electron beam lithography using the machine learning scheme. Normally in the work of artificial intelligence, the researchers focus on the output results from a neural network, such as success ratio in image recognition or improved production yield, etc. In this work, we put more focus on the weights connecting the nodes in a convolutional neural network, which are naturally the fractions of a point-spread function, and take out those weighted fractions after learning to be utilized as a tuned kernel. Proof-of-concept of the kernel tuning has been demonstrated using the examples of proximity effect correction with 2-layer network, and charging effect correction with 3-layer network. This type of new tuning method can be beneficial to give researchers more insights to come up with a better model, yet it might be too early to be deployed to production to give better critical dimension (CD) and positional accuracy almost instantly.

  11. Python framework for kinetic modeling of electronically excited reaction pathways

    Science.gov (United States)

    Verboncoeur, John; Parsey, Guy; Guclu, Yaman; Christlieb, Andrew

    2012-10-01

    The use of plasma energy to enhance and control the chemical reactions during combustion, a technology referred to as ``plasma assisted combustion'' (PAC), can result in a variety of beneficial effects: e.g. stable lean operation, pollution reduction, and wider range of p-T operating conditions. While experimental evidence abounds, theoretical understanding of PAC is at best incomplete, and numerical tools still lack in reliable predictive capabilities. In the context of a joint experimental-numerical effort at Michigan State University, we present here an open-source modular Python framework dedicated to the dynamic optimization of non-equilibrium PAC systems. Multiple sources of experimental reaction data, e.g. reaction rates, cross-sections and oscillator strengths, are used in order to quantify the effect of data uncertainty and limiting assumptions. A collisional-radiative model (CRM) is implemented to organize reactions by importance and as a potential means of measuring a non-Maxwellian electron energy distribution function (EEDF), when coupled to optical emission spectroscopy data. Finally, we explore scaling laws in PAC parameter space using a kinetic global model (KGM) accelerated with CRM optimized reaction sequences and sparse stiff integrators.

  12. The workshop on ecosystems modelling approaches for South ...

    African Journals Online (AJOL)

    roles played by models in the OMP approach, and raises questions about the costs of the data collection. (in particular) needed to apply a multispecies modelling approach in South African fisheries management. It then summarizes the deliberations of workshops held by the Scientific Committees of two international ma-.

  13. INTRODUCTION TO SUSTAINABLE MANAGEMENT APPROACHES AND REVITALIZATION TOOLS-ELECTRONIC (SMARTE): IMPROVING REVITALIZATION DECISIONS IN STELLA, MISSOURI

    Science.gov (United States)

    SMARTe (Sustainable Management Approaches and Revitalization Tools-electronic) is a web-based decision support tool being developed by the Office of Research and Development (ORD) in partnership with the Office of Brownfields Cleanup and ...

  14. A simple approach to modeling ductile failure.

    Energy Technology Data Exchange (ETDEWEB)

    Wellman, Gerald William

    2012-06-01

    Sandia National Laboratories has the need to predict the behavior of structures after the occurrence of an initial failure. In some cases determining the extent of failure, beyond initiation, is required, while in a few cases the initial failure is a design feature used to tailor the subsequent load paths. In either case, the ability to numerically simulate the initiation and propagation of failures is a highly desired capability. This document describes one approach to the simulation of failure initiation and propagation.

  15. Digital contract approach for consistent and predictable multimedia information delivery in electronic commerce

    Science.gov (United States)

    Konana, Prabhudev; Gupta, Alok; Whinston, Andrew B.

    1997-01-01

    A pure 'technological' solution to network quality problems is incomplete since any benefits from new technologies are offset by the demand from exponentially growing electronic commerce ad data-intensive applications. SInce an economic paradigm is implicit in electronic commerce, we propose a 'market-system' approach to improve quality of service. Quality of service for digital products takes on a different meaning since users view quality of service differently and value information differently. We propose a framework for electronic commerce that is based on an economic paradigm and mass-customization, and works as a wide-area distributed management system. In our framework, surrogate-servers act as intermediaries between information provides and end- users, and arrange for consistent and predictable information delivery through 'digital contracts.' These contracts are negotiated and priced based on economic principles. Surrogate servers pre-fetched, through replication, information from many different servers and consolidate based on demand expectations. In order to recognize users' requirements and process requests accordingly, real-time databases are central to our framework. We also propose that multimedia information be separated into slowly changing and rapidly changing data streams to improve response time requirements. Surrogate- servers perform the tasks of integration of these data streams that is transparent to end-users.

  16. Entanglement transfer from electrons to photons in quantum dots: an open quantum system approach

    International Nuclear Information System (INIS)

    Budich, Jan C; Trauzettel, Bjoern

    2010-01-01

    We investigate entanglement transfer from a system of two spin-entangled electron-hole pairs, each placed in a separate single mode cavity, to the photons emitted due to cavity leakage. Dipole selection rules and a splitting between the light hole and the heavy hole subbands are the crucial ingredients establishing a one-to-one correspondence between electron spins and circular photon polarizations. To account for the measurement of the photons as well as dephasing effects, we choose a stochastic Schroedinger equation and a conditional master equation approach, respectively. The influence of interactions with the environment as well as asymmetries in the coherent couplings on the photon entanglement is analysed for two concrete measurement schemes. The first one is designed to violate the Clauser-Horne-Shimony-Holt (CHSH) inequality, while the second one employs the visibility of interference fringes to prove the entanglement of the photons. Because of the spatial separation of the entangled electronic system over two quantum dots, a successful verification of entangled photons emitted by this system would imply the detection of nonlocal spin entanglement of massive particles in a solid state structure.

  17. First-principles momentum-dependent local ansatz approach to correlated electron system

    Science.gov (United States)

    Kakehashi, Yoshiro; Chandra, Sumal

    In spite of a great success of the density functional theory (DFT), quantitative description of correlated electron systems has not yet been achieved because of the difficulty in improvement of exchange-correlation potential. Toward the quantitative description of correlated electrons, we recently proposed the momentum-dependent local ansatz approach (MLA) based on the wavefunction method. The theory describes exactly the weak Coulomb interaction regime, and goes beyond the Gutzwiller wavefunction method in both the weak and strong interaction regimes. We present here the first principles version of the MLA, which is obtained by combining the LDA +U Hamiltonian with the MLA. We demonstrate that the theory describes quantitatively the Hund-rule correlation energies, the charge fluctuations, the amplitudes of local moments, the momentum distribution functions, as well as the mass enhancement factors in iron-group transition metals. The DFT does not describe these quantities because it is based on the Hohenberg-Kohn theorem and the Kohn-Sham independent-electron scheme.

  18. Advanced language modeling approaches, case study: Expert search

    NARCIS (Netherlands)

    Hiemstra, Djoerd

    2008-01-01

    This tutorial gives a clear and detailed overview of advanced language modeling approaches and tools, including the use of document priors, translation models, relevance models, parsimonious models and expectation maximization training. Expert search will be used as a case study to explain the

  19. Chemotaxis: A Multi-Scale Modeling Approach

    Science.gov (United States)

    Bhowmik, Arpan

    We are attempting to build a working simulation of population level self-organization in dictyostelium discoideum cells by combining existing models for chemo-attractant production and detection, along with phenomenological motility models. Our goal is to create a computationally-viable model-framework within which a population of cells can self-generate chemo-attractant waves and self-organize based on the directional cues of those waves. The work is a direct continuation of our previous work published in Physical Biology titled ``Excitable waves and direction-sensing in Dictyostelium Discoideum: steps towards a chemotaxis model''. This is a work in progress, no official draft/paper exists yet.

  20. An Integrated Approach to Modeling Evacuation Behavior

    Science.gov (United States)

    2011-02-01

    A spate of recent hurricanes and other natural disasters have drawn a lot of attention to the evacuation decision of individuals. Here we focus on evacuation models that incorporate two economic phenomena that seem to be increasingly important in exp...

  1. Infectious disease modeling a hybrid system approach

    CERN Document Server

    Liu, Xinzhi

    2017-01-01

    This volume presents infectious diseases modeled mathematically, taking seasonality and changes in population behavior into account, using a switched and hybrid systems framework. The scope of coverage includes background on mathematical epidemiology, including classical formulations and results; a motivation for seasonal effects and changes in population behavior, an investigation into term-time forced epidemic models with switching parameters, and a detailed account of several different control strategies. The main goal is to study these models theoretically and to establish conditions under which eradication or persistence of the disease is guaranteed. In doing so, the long-term behavior of the models is determined through mathematical techniques from switched systems theory. Numerical simulations are also given to augment and illustrate the theoretical results and to help study the efficacy of the control schemes.

  2. Challenges and opportunities for integrating lake ecosystem modelling approaches

    Science.gov (United States)

    Mooij, Wolf M.; Trolle, Dennis; Jeppesen, Erik; Arhonditsis, George; Belolipetsky, Pavel V.; Chitamwebwa, Deonatus B.R.; Degermendzhy, Andrey G.; DeAngelis, Donald L.; Domis, Lisette N. De Senerpont; Downing, Andrea S.; Elliott, J. Alex; Ruberto, Carlos Ruberto; Gaedke, Ursula; Genova, Svetlana N.; Gulati, Ramesh D.; Hakanson, Lars; Hamilton, David P.; Hipsey, Matthew R.; Hoen, Jochem 't; Hulsmann, Stephan; Los, F. Hans; Makler-Pick, Vardit; Petzoldt, Thomas; Prokopkin, Igor G.; Rinke, Karsten; Schep, Sebastiaan A.; Tominaga, Koji; Van Dam, Anne A.; Van Nes, Egbert H.; Wells, Scott A.; Janse, Jan H.

    2010-01-01

    A large number and wide variety of lake ecosystem models have been developed and published during the past four decades. We identify two challenges for making further progress in this field. One such challenge is to avoid developing more models largely following the concept of others ('reinventing the wheel'). The other challenge is to avoid focusing on only one type of model, while ignoring new and diverse approaches that have become available ('having tunnel vision'). In this paper, we aim at improving the awareness of existing models and knowledge of concurrent approaches in lake ecosystem modelling, without covering all possible model tools and avenues. First, we present a broad variety of modelling approaches. To illustrate these approaches, we give brief descriptions of rather arbitrarily selected sets of specific models. We deal with static models (steady state and regression models), complex dynamic models (CAEDYM, CE-QUAL-W2, Delft 3D-ECO, LakeMab, LakeWeb, MyLake, PCLake, PROTECH, SALMO), structurally dynamic models and minimal dynamic models. We also discuss a group of approaches that could all be classified as individual based: super-individual models (Piscator, Charisma), physiologically structured models, stage-structured models and trait-based models. We briefly mention genetic algorithms, neural networks, Kalman filters and fuzzy logic. Thereafter, we zoom in, as an in-depth example, on the multi-decadal development and application of the lake ecosystem model PCLake and related models (PCLake Metamodel, Lake Shira Model, IPH-TRIM3D-PCLake). In the discussion, we argue that while the historical development of each approach and model is understandable given its 'leading principle', there are many opportunities for combining approaches. We take the point of view that a single 'right' approach does not exist and should not be strived for. Instead, multiple modelling approaches, applied concurrently to a given problem, can help develop an integrative

  3. Modeling High Altitude EMP using a Non-Equilibrium Electron Swarm Model to Monitor Conduction Electron Evolution (LA-UR-15-26151)

    Science.gov (United States)

    Pusateri, E. N.; Morris, H. E.; Nelson, E.; Ji, W.

    2015-12-01

    Electromagnetic pulse (EMP) events in the atmosphere are important physical phenomena that occur through both man-made and natural processes, such as lightning, and can be disruptive to surrounding electrical systems. Due to the disruptive nature of EMP, it is important to accurately predict EMP evolution and propagation with computational models. In EMP, low-energy conduction electrons are produced from Compton electron or photoelectron ionizations with air. These conduction electrons continue to interact with the surrounding air and alter the EMP waveform. Many EMP simulation codes use an equilibrium ohmic model for computing the conduction current. The equilibrium model works well when the equilibration time is short compared to the rise time or duration of the EMP. However, at high altitude, the conduction electron equilibration time can be comparable to or longer than the rise time or duration of the EMP. This matters, for example, when calculating the EMP propagating upward toward a satellite. In these scenarios, the equilibrium ionization rate becomes very large for even a modest electric field. The ohmic model produces an unphysically large number of conduction electrons that prematurely and abruptly short the EMP in the simulation code. An electron swarm model, which simulates the time evolution of conduction electrons, can be used to overcome the limitations exhibited by the equilibrium ohmic model. We have developed and validated an electron swarm model in an environment characterized by electric field and pressure previously in Pusateri et al. (2015). This swarm model has been integrated into CHAP-LA, a state-of-the-art EMP code developed by researchers at Los Alamos National Laboratory, which previously calculated conduction current using an ohmic model. We demonstrate the EMP damping behavior caused by the ohmic model at high altitudes and show improvements on high altitude EMP modeling obtained by employing the swarm model.

  4. A new approach to modelling radiation noise in CCD's

    International Nuclear Information System (INIS)

    Chugg, A.; Hopkinson, G.

    1998-01-01

    The energy depositions reported by Monte Carlo electron-photon irradiation transport codes are subject to a random error due to the finite number of particle histories used to generate the results. These statistical variations, normally a nuisance, may also be identified with the real radiation noise effects experienced by CCD pixels in persistent radiation environments. This paper explores the practicability of such radiation noise modelling by applying the ACCEPT code from the ITS suite to the case of a shielded CCD exposed to an electron flux. The results are compared with those obtained in a subsequent electron irradiation of the CCD by a Van de Graaff accelerator

  5. "Dispersion modeling approaches for near road | Science ...

    Science.gov (United States)

    Roadway design and roadside barriers can have significant effects on the dispersion of traffic-generated pollutants, especially in the near-road environment. Dispersion models that can accurately simulate these effects are needed to fully assess these impacts for a variety of applications. For example, such models can be useful for evaluating the mitigation potential of roadside barriers in reducing near-road exposures and their associated adverse health effects. Two databases, a tracer field study and a wind tunnel study, provide measurements used in the development and/or validation of algorithms to simulate dispersion in the presence of noise barriers. The tracer field study was performed in Idaho Falls, ID, USA with a 6-m noise barrier and a finite line source in a variety of atmospheric conditions. The second study was performed in the meteorological wind tunnel at the US EPA and simulated line sources at different distances from a model noise barrier to capture the effect on emissions from individual lanes of traffic. In both cases, velocity and concentration measurements characterized the effect of the barrier on dispersion.This paper presents comparisons with the two datasets of the barrier algorithms implemented in two different dispersion models: US EPA’s R-LINE (a research dispersion modelling tool under development by the US EPA’s Office of Research and Development) and CERC’s ADMS model (ADMS-Urban). In R-LINE the physical features reveal

  6. An analytical approach to characterize morbidity profile dissimilarity between distinct cohorts using electronic medical records.

    Science.gov (United States)

    Schildcrout, Jonathan S; Basford, Melissa A; Pulley, Jill M; Masys, Daniel R; Roden, Dan M; Wang, Deede; Chute, Christopher G; Kullo, Iftikhar J; Carrell, David; Peissig, Peggy; Kho, Abel; Denny, Joshua C

    2010-12-01

    We describe a two-stage analytical approach for characterizing morbidity profile dissimilarity among patient cohorts using electronic medical records. We capture morbidities using the International Statistical Classification of Diseases and Related Health Problems (ICD-9) codes. In the first stage of the approach separate logistic regression analyses for ICD-9 sections (e.g., "hypertensive disease" or "appendicitis") are conducted, and the odds ratios that describe adjusted differences in prevalence between two cohorts are displayed graphically. In the second stage, the results from ICD-9 section analyses are combined into a general morbidity dissimilarity index (MDI). For illustration, we examine nine cohorts of patients representing six phenotypes (or controls) derived from five institutions, each a participant in the electronic MEdical REcords and GEnomics (eMERGE) network. The phenotypes studied include type II diabetes and type II diabetes controls, peripheral arterial disease and peripheral arterial disease controls, normal cardiac conduction as measured by electrocardiography, and senile cataracts. Copyright © 2010 Elsevier Inc. All rights reserved.

  7. Electronic approaches to making sense of the text in the adverse event reporting system.

    Science.gov (United States)

    Benin, Andrea L; Fodeh, Samah Jamal; Lee, Kyle; Koss, Michele; Miller, Perry; Brandt, Cynthia

    2016-08-01

    Health care organizations working to eliminate preventable harm and to improve patient safety must have robust programs to collect and to analyze data on adverse events in order to use the information to affect improvement. Such adverse event reporting systems are based on frontline personnel reporting issues that arise in the course of their daily work. Limitations in how existing software systems handle these reports mean that use of this potentially rich information is resource intensive and prone to variable results. The aim of this study was to develop an electronic approach to processing the text in medical event reports that would be reliable enough to be used to improve patient safety. At Connecticut Children's Medical Center, staff manually enter reports of adverse events into a web-based software tool. We evaluated the ability of 2 electronic methods-rule-based query and semi-supervised machine learning-to identify specific types of events ("use cases") versus a reference standard. Rule-based query was tested on 5 use cases and machine learning on a subset of 2 using 9164 events reported from February 2012-January 2014. Machine learning found 93% of the weight-based errors and 92% of the errors in patient-identification. Rule-based query had accuracy of 99% or greater, high precision, and high recall for all use cases. Electronic approaches to streamlining the use of adverse event reports are feasible to automate and valuable for categorizing this important data for use in improving patient safety. © 2016 American Society for Healthcare Risk Management of the American Hospital Association.

  8. First principles based multiparadigm modeling of electronic structures and dynamics

    Science.gov (United States)

    Xiao, Hai

    enabling the tunability of CBO. We predict that Na further improves the CBO through electrostatically elevating the valence levels to decrease the CBO, explaining the observed essential role of Na for high performance. Moreover we find that K leads to a dramatic decrease in the CBO to 0.05 eV, much better than Na. We suggest that the efficiency of CIGS devices might be improved substantially by tuning the ratio of Na to K, with the improved phase stability of Na balancing phase instability from K. All these defects reduce interfacial stability slightly, but not significantly. A number of exotic structures have been formed through high pressure chemistry, but applications have been hindered by difficulties in recovering the high pressure phase to ambient conditions (i.e., one atmosphere and room temperature). Here we use dispersion-corrected DFT (PBE-ulg flavor) to predict that above 60 GPa the most stable form of N2O (the laughing gas in its molecular form) is a 1D polymer with an all-nitrogen backbone analogous to cis-polyacetylene in which alternate N are bonded (ionic covalent) to O. The analogous trans-polymer is only 0.03-0.10 eV/molecular unit less stable. Upon relaxation to ambient conditions both polymers relax below 14 GPa to the same stable non-planar trans-polymer, accompanied by possible electronic structure transitions. The predicted phonon spectrum and dissociation kinetics validate the stability of this trans-poly-NNO at ambient conditions, which has potential applications as a new type of conducting polymer with all-nitrogen chains and as a high-energy oxidizer for rocket propulsion. This work illustrates in silico materials discovery particularly in the realm of extreme conditions. Modeling non-adiabatic electron dynamics has been a long-standing challenge for computational chemistry and materials science, and the eFF method presents a cost-efficient alternative. However, due to the deficiency of FSG representation, eFF is limited to low-Z elements with

  9. Modeling Photovoltaic Module-Level Power Electronics in the System Advisor Model; NREL (National Renewable Energy Laboratory)

    Energy Technology Data Exchange (ETDEWEB)

    None

    2015-07-01

    Module-level power electronics, such as DC power optimizers, microinverters, and those found in AC modules, are increasing in popularity in smaller-scale photovoltaic (PV) systems as their prices continue to decline. Therefore, it is important to provide PV modelers with guidelines about how to model these distributed power electronics appropriately in PV modeling software. This paper extends the work completed at NREL that provided recommendations to model the performance of distributed power electronics in NREL’s popular PVWatts calculator [1], to provide similar guidelines for modeling these technologies in NREL's more complex System Advisor Model (SAM). Module-level power electronics - such as DC power optimizers, microinverters, and those found in AC modules-- are increasing in popularity in smaller-scale photovoltaic (PV) systems as their prices continue to decline. Therefore, it is important to provide PV modelers with guidelines about how to model these distributed power electronics appropriately in PV modeling software.

  10. The COOLER Code: A Novel Analytical Approach to Calculate Subcellular Energy Deposition by Internal Electron Emitters.

    Science.gov (United States)

    Siragusa, Mattia; Baiocco, Giorgio; Fredericia, Pil M; Friedland, Werner; Groesser, Torsten; Ottolenghi, Andrea; Jensen, Mikael

    2017-08-01

    COmputation Of Local Electron Release (COOLER), a software program has been designed for dosimetry assessment at the cellular/subcellular scale, with a given distribution of administered low-energy electron-emitting radionuclides in cellular compartments, which remains a critical step in risk/benefit analysis for advancements in internal radiotherapy. The software is intended to overcome the main limitations of the medical internal radiation dose (MIRD) formalism for calculations of cellular S-values (i.e., dose to a target region in the cell per decay in a given source region), namely, the use of the continuous slowing down approximation (CSDA) and the assumption of a spherical cell geometry. To this aim, we developed an analytical approach, entrusted to a MATLAB-based program, using as input simulated data for electron spatial energy deposition directly derived from full Monte Carlo track structure calculations with PARTRAC. Results from PARTRAC calculations on electron range, stopping power and residual energy versus traveled distance curves are presented and, when useful for implementation in COOLER, analytical fit functions are given. Example configurations for cells in different culture conditions (V79 cells in suspension or adherent culture) with realistic geometrical parameters are implemented for use in the tool. Finally, cellular S-value predictions by the newly developed code are presented for different cellular geometries and activity distributions (uniform activity in the nucleus, in the entire cell or on the cell surface), validated against full Monte Carlo calculations with PARTRAC, and compared to MIRD standards, as well as results based on different track structure calculations (Geant4-DNA). The largest discrepancies between COOLER and MIRD predictions were generally found for electrons between 25 and 30 keV, where the magnitude of disagreement in S-values can vary from 50 to 100%, depending on the activity distribution. In calculations for

  11. Chemical and engineering approaches to enable organic field-effect transistors for electronic skin applications.

    Science.gov (United States)

    Sokolov, Anatoliy N; Tee, Benjamin C-K; Bettinger, Christopher J; Tok, Jeffrey B-H; Bao, Zhenan

    2012-03-20

    Skin is the body's largest organ and is responsible for the transduction of a vast amount of information. This conformable material simultaneously collects signals from external stimuli that translate into information such as pressure, pain, and temperature. The development of an electronic material, inspired by the complexity of this organ is a tremendous, unrealized engineering challenge. However, the advent of carbon-based electronics may offer a potential solution to this long-standing problem. In this Account, we describe the use of an organic field-effect transistor (OFET) architecture to transduce mechanical and chemical stimuli into electrical signals. In developing this mimic of human skin, we thought of the sensory elements of the OFET as analogous to the various layers and constituents of skin. In this fashion, each layer of the OFET can be optimized to carry out a specific recognition function. The separation of multimodal sensing among the components of the OFET may be considered a "divide and conquer" approach, where the electronic skin (e-skin) can take advantage of the optimized chemistry and materials properties of each layer. This design of a novel microstructured gate dielectric has led to unprecedented sensitivity for tactile pressure events. Typically, pressure-sensitive components within electronic configurations have suffered from a lack of sensitivity or long mechanical relaxation times often associated with elastomeric materials. Within our method, these components are directly compatible with OFETs and have achieved the highest reported sensitivity to date. Moreover, the tactile sensors operate on a time scale comparable with human skin, making them ideal candidates for integration as synthetic skin devices. The methodology is compatible with large-scale fabrication and employs simple, commercially available elastomers. The design of materials within the semiconductor layer has led to the incorporation of selectivity and sensitivity within

  12. ANALYSIS OF DOMESTIC AND INTERNATIONAL APPROACHES TO THE ADVANCED EDUCATIONAL PRACTICES IN THE ELECTRONIC NETWORK ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Tatiana N. Noskova

    2016-12-01

    Full Text Available Introduction: human activities related to the use of information are being transformed under the influence of computer technology. Variable solutions to information problems are emerging; demands and require¬ments for the competence are changing on the labour market. Educational practices are destined to form a new learning behaviour for the 21st century, adopting lifelong learning strategy. The main purpose of the article is to answer the question as to how to transform existing pedagogical theory and practice under current conditions of electronic environment. Publishing of this article is coherent with concept of the journal Integration of Education, analyzing Russian and world experience in the development of education systems. This approach is important for dissemination and implementation in practice. This article explores the challenges of information technology and technical support of the educational process in universities and schools. The study of these issues is in the field of view of the journa l. Materials and Methods: the paper elaborates on the results of domestic and international educational theory and practice, comparison methods, drawing on student’s survey in the framework of international research in the field of e-learning in higher education institutions. Results: the main approaches, applied to the formulation of educational practices in the electronic environ-ment, were analyzed. The most topical national approaches include system, activity, polysubject (dialogical, context, and dialogical ones. Among international approaches self-directed learning, educational communication strategies, experiential learning, training in partnership, collaborative learning, learning in online communities, situational training were analyzed. Specifics of electronic educational interactions with distributed in time and space activities of teachers and students, create the preconditions for the implementation of new educational

  13. A consortium approach to glass furnace modeling.

    Energy Technology Data Exchange (ETDEWEB)

    Chang, S.-L.; Golchert, B.; Petrick, M.

    1999-04-20

    Using computational fluid dynamics to model a glass furnace is a difficult task for any one glass company, laboratory, or university to accomplish. The task of building a computational model of the furnace requires knowledge and experience in modeling two dissimilar regimes (the combustion space and the liquid glass bath), along with the skill necessary to couple these two regimes. Also, a detailed set of experimental data is needed in order to evaluate the output of the code to ensure that the code is providing proper results. Since all these diverse skills are not present in any one research institution, a consortium was formed between Argonne National Laboratory, Purdue University, Mississippi State University, and five glass companies in order to marshal these skills into one three-year program. The objective of this program is to develop a fully coupled, validated simulation of a glass melting furnace that may be used by industry to optimize the performance of existing furnaces.

  14. Fractal approach to computer-analytical modelling of tree crown

    International Nuclear Information System (INIS)

    Berezovskaya, F.S.; Karev, G.P.; Kisliuk, O.F.; Khlebopros, R.G.; Tcelniker, Yu.L.

    1993-09-01

    In this paper we discuss three approaches to the modeling of a tree crown development. These approaches are experimental (i.e. regressive), theoretical (i.e. analytical) and simulation (i.e. computer) modeling. The common assumption of these is that a tree can be regarded as one of the fractal objects which is the collection of semi-similar objects and combines the properties of two- and three-dimensional bodies. We show that a fractal measure of crown can be used as the link between the mathematical models of crown growth and light propagation through canopy. The computer approach gives the possibility to visualize a crown development and to calibrate the model on experimental data. In the paper different stages of the above-mentioned approaches are described. The experimental data for spruce, the description of computer system for modeling and the variant of computer model are presented. (author). 9 refs, 4 figs

  15. Accounting for misclassification in electronic health records-derived exposures using generalized linear finite mixture models.

    Science.gov (United States)

    Hubbard, Rebecca A; Johnson, Eric; Chubak, Jessica; Wernli, Karen J; Kamineni, Aruna; Bogart, Andy; Rutter, Carolyn M

    2017-06-01

    Exposures derived from electronic health records (EHR) may be misclassified, leading to biased estimates of their association with outcomes of interest. An example of this problem arises in the context of cancer screening where test indication, the purpose for which a test was performed, is often unavailable. This poses a challenge to understanding the effectiveness of screening tests because estimates of screening test effectiveness are biased if some diagnostic tests are misclassified as screening. Prediction models have been developed for a variety of exposure variables that can be derived from EHR, but no previous research has investigated appropriate methods for obtaining unbiased association estimates using these predicted probabilities. The full likelihood incorporating information on both the predicted probability of exposure-class membership and the association between the exposure and outcome of interest can be expressed using a finite mixture model. When the regression model of interest is a generalized linear model (GLM), the expectation-maximization algorithm can be used to estimate the parameters using standard software for GLMs. Using simulation studies, we compared the bias and efficiency of this mixture model approach to alternative approaches including multiple imputation and dichotomization of the predicted probabilities to create a proxy for the missing predictor. The mixture model was the only approach that was unbiased across all scenarios investigated. Finally, we explored the performance of these alternatives in a study of colorectal cancer screening with colonoscopy. These findings have broad applicability in studies using EHR data where gold-standard exposures are unavailable and prediction models have been developed for estimating proxies.

  16. Combined convective and diffusive modeling of the ring current and radiation belt electron dynamics using the VERB-4D code

    Science.gov (United States)

    Aseev, N.; Shprits, Y.; Drozdov, A.; Kellerman, A. C.; Wang, D.

    2017-12-01

    Ring current and radiation belts are key elements in the global dynamics of the Earth's magnetosphere. Comprehensive mathematical models are useful tools that allow us to understand the multiscale dynamics of these charged particle populations. In this work, we present results of simulations of combined ring current - radiation belt electron dynamics using the four-dimensional Versatile Electron Radiation Belt (VERB-4D) code. The VERB-4D code solves the modified Fokker-Planck equation including convective terms and models simultaneously ring current (1 - 100 keV) and radiation belt (100 keV - several MeV) electron dynamics. We apply the code to the number of geomagnetic storms that occurred in the past, compare the results with different satellite observations, and show how low-energy particles can affect the high-energy populations. Particularly, we use data from Polar Operational Environmental Satellite (POES) mission that provides a very good MLT coverage with 1.5-hour time resolution. The POES data allow us to validate the approach of the VERB-4D code for modeling MLT-dependent processes such as electron drift, wave-particle interactions, and magnetopause shadowing. We also show how different simulation parameters and empirical models can affect the results, making a particular emphasis on the electric and magnetic field models. This work will help us reveal advantages and disadvantages of the approach behind the code and determine its prediction efficiency.

  17. Modelling the main ionospheric trough using the Electron Density Assimilative Model (EDAM) with assimilated GPS TEC

    Science.gov (United States)

    Parker, James A. D.; Eleri Pryse, S.; Jackson-Booth, Natasha; Buckland, Rachel A.

    2018-01-01

    The main ionospheric trough is a large-scale spatial depletion in the electron density distribution at the interface between the high- and mid-latitude ionosphere. In western Europe it appears in early evening, progresses equatorward during the night, and retreats rapidly poleward at dawn. It exhibits substantial day-to-day variability and under conditions of increased geomagnetic activity it moves progressively to lower latitudes. Steep gradients on the trough-walls on either side of the trough minimum, and their variability, can cause problems for radio applications. Numerous studies have sought to characterize and quantify the trough behaviour. The Electron Density Assimilative Model (EDAM) models the ionosphere on a global scale. It assimilates observations into a background ionosphere, the International Reference Ionosphere 2007 (IRI2007), to provide a full 3-D representation of the ionospheric plasma distribution at specified times and days. This current investigation studied the capability of EDAM to model the ionosphere in the region of the main trough. Total electron content (TEC) measurements from 46 GPS stations in western Europe from September to December 2002 were assimilated into EDAM to provide a model of the ionosphere in the trough region. Vertical electron content profiles through the model revealed the trough and the detail of its structure. Statistical results are presented of the latitude of the trough minimum, TEC at the minimum and of other defined parameters that characterize the trough structure. The results are compared with previous observations made with the Navy Ionospheric Monitoring System (NIMS), and reveal the potential of EDAM to model the large-scale structure of the ionosphere.

  18. Phytoplankton as Particles - A New Approach to Modeling Algal Blooms

    Science.gov (United States)

    2013-07-01

    ER D C/ EL T R -1 3 -1 3 Civil Works Basic Research Program Phytoplankton as Particles – A New Approach to Modeling Algal Blooms E nv... Phytoplankton as Particles – A New Approach to Modeling Algal Blooms Carl F. Cerco and Mark R. Noel Environmental Laboratory U.S. Army Engineer Research... phytoplankton blooms can be modeled by treating phytoplankton as discrete particles capable of self- induced transport via buoyancy regulation or other

  19. Contribution of a companion modelling approach

    African Journals Online (AJOL)

    2009-09-16

    Sep 16, 2009 ... This paper describes the role of participatory modelling and simulation as a way to provide a meaningful framework to enable actors to understand the interdependencies in peri-urban catchment management. A role-playing game, connecting the quantitative and qualitative dynamics of the resources with ...

  20. Numerical modelling approach for mine backfill

    Indian Academy of Sciences (India)

    Muhammad Zaka Emad

    2017-07-24

    Jul 24, 2017 ... Abstract. Numerical modelling is broadly used for assessing complex scenarios in underground mines, including mining sequence and blast-induced vibrations from production blasting. Sublevel stoping mining methods with delayed backfill are extensively used to exploit steeply dipping ore bodies by ...

  1. Energy and development : A modelling approach

    NARCIS (Netherlands)

    van Ruijven, B.J.|info:eu-repo/dai/nl/304834521

    2008-01-01

    Rapid economic growth of developing countries like India and China implies that these countries become important actors in the global energy system. Examples of this impact are the present day oil shortages and rapidly increasing emissions of greenhouse gases. Global energy models are used explore

  2. Numerical modelling approach for mine backfill

    Indian Academy of Sciences (India)

    Muhammad Zaka Emad

    2017-07-24

    Jul 24, 2017 ... pulse is applied as a stress history on the CRF stope. Blast wave data obtained from the on-site monitoring are very complex. It requires processing before interpreting and using it for numerical models. Generally, mining compa- nies hire geophysics experts for interpretation of such data. The blast wave ...

  3. A new approach to model mixed hydrates

    Czech Academy of Sciences Publication Activity Database

    Hielscher, S.; Vinš, Václav; Jäger, A.; Hrubý, Jan; Breitkopf, C.; Span, R.

    2018-01-01

    Roč. 459, March (2018), s. 170-185 ISSN 0378-3812 R&D Projects: GA ČR(CZ) GA17-08218S Institutional support: RVO:61388998 Keywords : gas hydrate * mixture * modeling Subject RIV: BJ - Thermodynamics Impact factor: 2.473, year: 2016 https://www. science direct.com/ science /article/pii/S0378381217304983

  4. Energy and Development. A Modelling Approach

    International Nuclear Information System (INIS)

    Van Ruijven, B.J.

    2008-01-01

    Rapid economic growth of developing countries like India and China implies that these countries become important actors in the global energy system. Examples of this impact are the present day oil shortages and rapidly increasing emissions of greenhouse gases. Global energy models are used to explore possible future developments of the global energy system and identify policies to prevent potential problems. Such estimations of future energy use in developing countries are very uncertain. Crucial factors in the future energy use of these regions are electrification, urbanisation and income distribution, issues that are generally not included in present day global energy models. Model simulations in this thesis show that current insight in developments in low-income regions lead to a wide range of expected energy use in 2030 of the residential and transport sectors. This is mainly caused by many different model calibration options that result from the limited data availability for model development and calibration. We developed a method to identify the impact of model calibration uncertainty on future projections. We developed a new model for residential energy use in India, in collaboration with the Indian Institute of Science. Experiments with this model show that the impact of electrification and income distribution is less univocal than often assumed. The use of fuelwood, with related health risks, can decrease rapidly if the income of poor groups increases. However, there is a trade off in terms of CO2 emissions because these groups gain access to electricity and the ownership of appliances increases. Another issue is the potential role of new technologies in developing countries: will they use the opportunities of leapfrogging? We explored the potential role of hydrogen, an energy carrier that might play a central role in a sustainable energy system. We found that hydrogen only plays a role before 2050 under very optimistic assumptions. Regional energy

  5. Energy and Development. A Modelling Approach

    Energy Technology Data Exchange (ETDEWEB)

    Van Ruijven, B.J.

    2008-12-17

    Rapid economic growth of developing countries like India and China implies that these countries become important actors in the global energy system. Examples of this impact are the present day oil shortages and rapidly increasing emissions of greenhouse gases. Global energy models are used to explore possible future developments of the global energy system and identify policies to prevent potential problems. Such estimations of future energy use in developing countries are very uncertain. Crucial factors in the future energy use of these regions are electrification, urbanisation and income distribution, issues that are generally not included in present day global energy models. Model simulations in this thesis show that current insight in developments in low-income regions lead to a wide range of expected energy use in 2030 of the residential and transport sectors. This is mainly caused by many different model calibration options that result from the limited data availability for model development and calibration. We developed a method to identify the impact of model calibration uncertainty on future projections. We developed a new model for residential energy use in India, in collaboration with the Indian Institute of Science. Experiments with this model show that the impact of electrification and income distribution is less univocal than often assumed. The use of fuelwood, with related health risks, can decrease rapidly if the income of poor groups increases. However, there is a trade off in terms of CO2 emissions because these groups gain access to electricity and the ownership of appliances increases. Another issue is the potential role of new technologies in developing countries: will they use the opportunities of leapfrogging? We explored the potential role of hydrogen, an energy carrier that might play a central role in a sustainable energy system. We found that hydrogen only plays a role before 2050 under very optimistic assumptions. Regional energy

  6. Modeling of Electronic Properties in Organic Semiconductor Device Structures

    Science.gov (United States)

    Chang, Hsiu-Chuang

    Organic semiconductors (OSCs) have recently become viable for a wide range of electronic devices, some of which have already been commercialized. With the mechanical flexibility of organic materials and promising performance of organic field effect transistors (OFETs) and organic bulk heterojunction devices, OSCs have been demonstrated in applications such as radio frequency identification tags, flexible displays, and photovoltaic cells. Transient phenomena play decisive roles in the performance of electronic devices and OFETs in particular. The dynamics of the establishment and depletion of the conducting channel in OFETs are investigated theoretically. The device structures explored resemble typical organic thin-film transistors with one of the channel contacts removed. By calculating the displacement current associated with charging and discharging of the channel in these capacitors, transient effects on the carrier transport in OSCs may be studied. In terms of the relevant models it is shown that the non-linearity of the process plays a key role. The non-linearity arises in the simplest case from the fact that channel resistance varies during the charging and discharging phases. Traps can be introduced into the models and their effects examined in some detail. When carriers are injected into the device, a conducting channel is established with traps that are initially empty. Gradual filling of the traps then modifies the transport characteristics of the injected charge carriers. In contrast, dc measurements as they are typically performed to characterize the transport properties of organic semiconductor channels investigate a steady state with traps partially filled. Numerical and approximate analytical models of the formation of the conducting channel and the resulting displacement currents are presented. For the process of transient carrier extraction, it is shown that if the channel capacitance is partially or completely discharged through the channel

  7. Model of nanodegradation processes in electronic equipment of NPP Kozloduy

    International Nuclear Information System (INIS)

    J. Boucher Blvd, 1164 Sofia, BG (Bulgaria))" data-affiliation=" (Sofia University, Faculty of Physics, 5 J. Boucher Blvd, 1164 Sofia, BG (Bulgaria))" >Popov, A

    2014-01-01

    From the complex studies it was proof that the main degradation processes in the three groups of elements for the extended period of time are slow; do not lead to a hopping change in basic parameters and to catastrophic failures. This gives grounds to suggest a common diffusion model, which is limited to the following: -in electronic components containing a p-n junction, is performed diffusion of residual cooper atoms, that are accumulated in the area of a spatial charge under the influence of the electric field and the local temperature, creating micro-shunt regions; -in the contactor systems whose contact surfaces are made of metal alloys under the influence of increased temperature starts decomposition of a homogeneous alloy. Conditions are created for diffusion of individual atoms to the surface, micro-phases of homogeneous atoms are formed and modify the contact resistances; -in the course of time in the insulating materials are changed the mechanisms of polarization, double bonds and dipoles are disrupting, leading to the release of carbon atoms. The latter diffuse at elevated temperatures and form conductive cords, which amend the dielectric losses and the specific resistance of the materials

  8. Model of nanodegradation processes in electronic equipment of NPP Kozloduy

    Science.gov (United States)

    Popov, A.

    2014-12-01

    From the complex studies it was proof that the main degradation processes in the three groups of elements for the extended period of time are slow; do not lead to a hopping change in basic parameters and to catastrophic failures. This gives grounds to suggest a common diffusion model, which is limited to the following: -in electronic components containing a p-n junction, is performed diffusion of residual cooper atoms, that are accumulated in the area of a spatial charge under the influence of the electric field and the local temperature, creating micro-shunt regions; -in the contactor systems whose contact surfaces are made of metal alloys under the influence of increased temperature starts decomposition of a homogeneous alloy. Conditions are created for diffusion of individual atoms to the surface, micro-phases of homogeneous atoms are formed and modify the contact resistances; -in the course of time in the insulating materials are changed the mechanisms of polarization, double bonds and dipoles are disrupting, leading to the release of carbon atoms. The latter diffuse at elevated temperatures and form conductive cords, which amend the dielectric losses and the specific resistance of the materials.

  9. A Novel Feature Extraction Approach Using Window Function Capturing and QPSO-SVM for Enhancing Electronic Nose Performance.

    Science.gov (United States)

    Guo, Xiuzhen; Peng, Chao; Zhang, Songlin; Yan, Jia; Duan, Shukai; Wang, Lidan; Jia, Pengfei; Tian, Fengchun

    2015-06-29

    In this paper, a novel feature extraction approach which can be referred to as moving window function capturing (MWFC) has been proposed to analyze signals of an electronic nose (E-nose) used for detecting types of infectious pathogens in rat wounds. Meanwhile, a quantum-behaved particle swarm optimization (QPSO) algorithm is implemented in conjunction with support vector machine (SVM) for realizing a synchronization optimization of the sensor array and SVM model parameters. The results prove the efficacy of the proposed method for E-nose feature extraction, which can lead to a higher classification accuracy rate compared to other established techniques. Meanwhile it is interesting to note that different classification results can be obtained by changing the types, widths or positions of windows. By selecting the optimum window function for the sensor response, the performance of an E-nose can be enhanced.

  10. A Novel Feature Extraction Approach Using Window Function Capturing and QPSO-SVM for Enhancing Electronic Nose Performance

    Directory of Open Access Journals (Sweden)

    Xiuzhen Guo

    2015-06-01

    Full Text Available In this paper, a novel feature extraction approach which can be referred to as moving window function capturing (MWFC has been proposed to analyze signals of an electronic nose (E-nose used for detecting types of infectious pathogens in rat wounds. Meanwhile, a quantum-behaved particle swarm optimization (QPSO algorithm is implemented in conjunction with support vector machine (SVM for realizing a synchronization optimization of the sensor array and SVM model parameters. The results prove the efficacy of the proposed method for E-nose feature extraction, which can lead to a higher classification accuracy rate compared to other established techniques. Meanwhile it is interesting to note that different classification results can be obtained by changing the types, widths or positions of windows. By selecting the optimum window function for the sensor response, the performance of an E-nose can be enhanced.

  11. Dynamic Metabolic Model Building Based on the Ensemble Modeling Approach

    Energy Technology Data Exchange (ETDEWEB)

    Liao, James C. [Univ. of California, Los Angeles, CA (United States)

    2016-10-01

    Ensemble modeling of kinetic systems addresses the challenges of kinetic model construction, with respect to parameter value selection, and still allows for the rich insights possible from kinetic models. This project aimed to show that constructing, implementing, and analyzing such models is a useful tool for the metabolic engineering toolkit, and that they can result in actionable insights from models. Key concepts are developed and deliverable publications and results are presented.

  12. Model of charge-state distributions for electron cyclotron resonance ion source plasmas

    Directory of Open Access Journals (Sweden)

    D. H. Edgell

    1999-12-01

    Full Text Available A computer model for the ion charge-state distribution (CSD in an electron cyclotron resonance ion source (ECRIS plasma is presented that incorporates non-Maxwellian distribution functions, multiple atomic species, and ion confinement due to the ambipolar potential well that arises from confinement of the electron cyclotron resonance (ECR heated electrons. Atomic processes incorporated into the model include multiple ionization and multiple charge exchange with rate coefficients calculated for non-Maxwellian electron distributions. The electron distribution function is calculated using a Fokker-Planck code with an ECR heating term. This eliminates the electron temperature as an arbitrary user input. The model produces results that are a good match to CSD data from the ANL-ECRII ECRIS. Extending the model to 1D axial will also allow the model to determine the plasma and electrostatic potential profiles, further eliminating arbitrary user input to the model.

  13. Integration models: multicultural and liberal approaches confronted

    Science.gov (United States)

    Janicki, Wojciech

    2012-01-01

    European societies have been shaped by their Christian past, upsurge of international migration, democratic rule and liberal tradition rooted in religious tolerance. Boosting globalization processes impose new challenges on European societies, striving to protect their diversity. This struggle is especially clearly visible in case of minorities trying to resist melting into mainstream culture. European countries' legal systems and cultural policies respond to these efforts in many ways. Respecting identity politics-driven group rights seems to be the most common approach, resulting in creation of a multicultural society. However, the outcome of respecting group rights may be remarkably contradictory to both individual rights growing out from liberal tradition, and to reinforced concept of integration of immigrants into host societies. The hereby paper discusses identity politics upturn in the context of both individual rights and integration of European societies.

  14. Modelling thermal plume impacts - Kalpakkam approach

    International Nuclear Information System (INIS)

    Rao, T.S.; Anup Kumar, B.; Narasimhan, S.V.

    2002-01-01

    A good understanding of temperature patterns in the receiving waters is essential to know the heat dissipation from thermal plumes originating from coastal power plants. The seasonal temperature profiles of the Kalpakkam coast near Madras Atomic Power Station (MAPS) thermal out fall site are determined and analysed. It is observed that the seasonal current reversal in the near shore zone is one of the major mechanisms for the transport of effluents away from the point of mixing. To further refine our understanding of the mixing and dilution processes, it is necessary to numerically simulate the coastal ocean processes by parameterising the key factors concerned. In this paper, we outline the experimental approach to achieve this objective. (author)

  15. A New Approach to Modeling Jupiter's Magnetosphere

    Science.gov (United States)

    Fukazawa, K.; Katoh, Y.; Walker, R. J.; Kimura, T.; Tsuchiya, F.; Murakami, G.; Kita, H.; Tao, C.; Murata, K. T.

    2017-12-01

    The scales in planetary magnetospheres range from 10s of planetary radii to kilometers. For a number of years we have studied the magnetospheres of Jupiter and Saturn by using 3-dimensional magnetohydrodynamic (MHD) simulations. However, we have not been able to reach even the limits of the MHD approximation because of the large amount of computer resources required. Recently thanks to the progress in supercomputer systems, we have obtained the capability to simulate Jupiter's magnetosphere with 1000 times the number of grid points used in our previous simulations. This has allowed us to combine the high resolution global simulation with a micro-scale simulation of the Jovian magnetosphere. In particular we can combine a hybrid (kinetic ions and fluid electrons) simulation with the MHD simulation. In addition, the new capability enables us to run multi-parameter survey simulations of the Jupiter-solar wind system. In this study we performed a high-resolution simulation of Jovian magnetosphere to connect with the hybrid simulation, and lower resolution simulations under the various solar wind conditions to compare with Hisaki and Juno observations. In the high-resolution simulation we used a regular Cartesian gird with 0.15 RJ grid spacing and placed the inner boundary at 7 RJ. From these simulation settings, we provide the magnetic field out to around 20 RJ from Jupiter as a background field for the hybrid simulation. For the first time we have been able to resolve Kelvin Helmholtz waves on the magnetopause. We have investigated solar wind dynamic pressures between 0.01 and 0.09 nPa for a number of IMF values. These simulation data are open for the registered users to download the raw data. We have compared the results of these simulations with Hisaki auroral observations.

  16. Modelling approach for photochemical pollution studies

    International Nuclear Information System (INIS)

    Silibello, C.; Catenacci, G.; Calori, G.; Crapanzano, G.; Pirovano, G.

    1996-01-01

    The comprehension of the relationships between primary pollutants emissions and secondary pollutants concentration and deposition is necessary to design policies and strategies for the maintenance of a healthy environment. The use of mathematical models is a powerful tool to assess the effect of the emissions and of physical and chemical transformations of pollutants on air quality. A photochemical model, Calgrid, developed by CARB (California Air Resources Board), has been used to test the effect of different meteorological and air quality, scenarios on the ozone concentration levels. This way we can evaluate the influence of these conditions to determine the most important chemical species and reactions in atmosphere. The ozone levels are strongly related to the reactive hydrocarbons concentrations and to the solar radiation flux

  17. Colour texture segmentation using modelling approach

    Czech Academy of Sciences Publication Activity Database

    Haindl, Michal; Mikeš, Stanislav

    2005-01-01

    Roč. 3687, č. - (2005), s. 484-491 ISSN 0302-9743. [International Conference on Advances in Pattern Recognition /3./. Bath, 22.08.2005-25.08.2005] R&D Projects: GA MŠk 1M0572; GA AV ČR 1ET400750407; GA AV ČR IAA2075302 Institutional research plan: CEZ:AV0Z10750506 Keywords : colour texture segmentation * image models * segmentation benchmark Subject RIV: BD - Theory of Information

  18. Tumour resistance to cisplatin: a modelling approach

    International Nuclear Information System (INIS)

    Marcu, L; Bezak, E; Olver, I; Doorn, T van

    2005-01-01

    Although chemotherapy has revolutionized the treatment of haematological tumours, in many common solid tumours the success has been limited. Some of the reasons for the limitations are: the timing of drug delivery, resistance to the drug, repopulation between cycles of chemotherapy and the lack of complete understanding of the pharmacokinetics and pharmacodynamics of a specific agent. Cisplatin is among the most effective cytotoxic agents used in head and neck cancer treatments. When modelling cisplatin as a single agent, the properties of cisplatin only have to be taken into account, reducing the number of assumptions that are considered in the generalized chemotherapy models. The aim of the present paper is to model the biological effect of cisplatin and to simulate the consequence of cisplatin resistance on tumour control. The 'treated' tumour is a squamous cell carcinoma of the head and neck, previously grown by computer-based Monte Carlo techniques. The model maintained the biological constitution of a tumour through the generation of stem cells, proliferating cells and non-proliferating cells. Cell kinetic parameters (mean cell cycle time, cell loss factor, thymidine labelling index) were also consistent with the literature. A sensitivity study on the contribution of various mechanisms leading to drug resistance is undertaken. To quantify the extent of drug resistance, the cisplatin resistance factor (CRF) is defined as the ratio between the number of surviving cells of the resistant population and the number of surviving cells of the sensitive population, determined after the same treatment time. It is shown that there is a supra-linear dependence of CRF on the percentage of cisplatin-DNA adducts formed, and a sigmoid-like dependence between CRF and the percentage of cells killed in resistant tumours. Drug resistance is shown to be a cumulative process which eventually can overcome tumour regression leading to treatment failure

  19. ISM Approach to Model Offshore Outsourcing Risks

    Directory of Open Access Journals (Sweden)

    Sunand Kumar

    2014-07-01

    Full Text Available In an effort to achieve a competitive advantage via cost reductions and improved market responsiveness, organizations are increasingly employing offshore outsourcing as a major component of their supply chain strategies. But as evident from literature number of risks such as Political risk, Risk due to cultural differences, Compliance and regulatory risk, Opportunistic risk and Organization structural risk, which adversely affect the performance of offshore outsourcing in a supply chain network. This also leads to dissatisfaction among different stake holders. The main objective of this paper is to identify and understand the mutual interaction among various risks which affect the performance of offshore outsourcing.  To this effect, authors have identified various risks through extant review of literature.  From this information, an integrated model using interpretive structural modelling (ISM for risks affecting offshore outsourcing is developed and the structural relationships between these risks are modeled.  Further, MICMAC analysis is done to analyze the driving power and dependency of risks which shall be helpful to managers to identify and classify important criterions and to reveal the direct and indirect effects of each criterion on offshore outsourcing. Results show that political risk and risk due to cultural differences are act as strong drivers.

  20. Understanding Contrasting Approaches to Nationwide Implementations of Electronic Health Record Systems: England, the USA and Australia

    Directory of Open Access Journals (Sweden)

    Zoe Morrison

    2011-01-01

    Full Text Available As governments commit to national electronic health record (EHR systems, there is increasing international interest in identifying effective implementation strategies. We draw on Coiera's typology of national programmes - ‘top-down’, ‘bottom-up’ and ‘middle-out’ - to review EHR implementation strategies in three exemplar countries: England, the USA and Australia. In comparing and contrasting three approaches, we show how different healthcare systems, national policy contexts and anticipated benefits have shaped initial strategies. We reflect on progress and likely developments in the face of continually changing circumstances. Our review shows that irrespective of the initial strategy, over time there is likely to be convergence on the negotiated, devolved middle-out approach, which aims to balance the interests and responsibilities of local healthcare constituencies and national government to achieve national connectivity. We conclude that, accepting the current lack of empirical evidence, the flexibility offered by the middle-out approach may make this the best initial national strategy.

  1. Test of theoretical models for ultrafast heterogeneous electron ...

    Indian Academy of Sciences (India)

    Administrator

    (UHV) chambers, each equipped with a load-lock port, were employed for preparing and characteriz- ing the samples. A mobile UHV chamber served as the shuttle ..... there is no automatic transition to adiabatic electron transfer for high electronic coupling strength and the excitation of high energy vibrational modes can not.

  2. Developing Argumentation Strategies in Electronic Dialogs: Is Modeling Effective?

    Science.gov (United States)

    Mayweg-Paus, Elisabeth; Macagno, Fabrizio; Kuhn, Deanna

    2016-01-01

    The study presented here examines how interacting with a more capable interlocutor influences use of argumentation strategies in electronic discourse. To address this question, 54 young adolescents participating in an intervention centered on electronic peer dialogs were randomly assigned to either an experimental or control condition. In both…

  3. Computational modelling of the Li effects on the electronic structure of porous silicon

    Science.gov (United States)

    Gomez-Herrera, María Lucero; Miranda Durán, Álvaro; Trejo Baños, Alejandro; Cruz Irisson, Miguel

    This work analyses the effects of Li impurities on the electronic structure of pSi by means of the density functional theory with the generalized gradient approximation and the supercell scheme. The porous structures were modeled by removing atoms in the [001] direction of an otherwise perfect Si crystal. All surface dangling bonds were saturated with H atoms. To model the Li impurities some H atoms are replaced with Li atoms at the surface. Results show additional bands around the Fermi level with the insertion of a single Li atom on the pore surface, which suggests a trap-like state of localized charge. With increasing concentration of surface Li the band gap gradually decreases approaching to a metallic behavior. This results could be important to the application of pSi in Li-ion batteries This work was partially supported by CONACYT infrastructure project 252749.

  4. Electron kinetics modeling in a weakly ionized gas

    International Nuclear Information System (INIS)

    Boeuf, Jean-Pierre

    1985-01-01

    This work presents some features of electron kinetics in a weakly ionized gas. After a summary of the basis and recent developments of the kinetic theory, and a review of the most efficient numerical techniques for solving the Boltzmann equation, several aspects of electron motion in gases are analysed. Relaxation phenomena toward equilibrium under a uniform electric field, and the question of the existence of the hydrodynamic regime are first studied. The coupling between electron kinetics and chemical kinetics due to second kind collisions in Nitrogen is then analysed; a quantitative description of the evolution of the energy balance, accounting for electron-molecule as well as molecule-molecule energy transfer is also given. Finally, electron kinetics in space charge distorted, highly non uniform electric fields (glow discharges, streamers propagation) is investigated with microscopic numerical methods based on Boltzmann and Poisson equations. (author) [fr

  5. The improved DGR analytical model of electron density height profile and total electron content in the ionosphere

    OpenAIRE

    Radicella, S. M.; Zhang, M. L.

    1995-01-01

    Tests of the analytical model of the electron density profile originally proposed by G, Di Giovanni and S.M. Radicella (DGR model) have shown the need to introduce improvements in order to obtain a model able to reproduce the ionosphere in a larger spectrum of geophysical and time conditions. The present paper reviews the steps toward such progress and presents the final formulation of the model. It gives also a brief re- view of tests of the improved model done by different authors.

  6. Agribusiness model approach to territorial food development

    Directory of Open Access Journals (Sweden)

    Murcia Hector Horacio

    2011-04-01

    Full Text Available

    Several research efforts have coordinated the academic program of Agricultural Business Management from the University De La Salle (Bogota D.C., to the design and implementation of a sustainable agribusiness model applied to food development, with territorial projection. Rural development is considered as a process that aims to improve the current capacity and potential of the inhabitant of the sector, which refers not only to production levels and productivity of agricultural items. It takes into account the guidelines of the Organization of the United Nations “Millennium Development Goals” and considered the concept of sustainable food and agriculture development, including food security and nutrition in an integrated interdisciplinary context, with holistic and systemic dimension. Analysis is specified by a model with an emphasis on sustainable agribusiness production chains related to agricultural food items in a specific region. This model was correlated with farm (technical objectives, family (social purposes and community (collective orientations projects. Within this dimension are considered food development concepts and methodologies of Participatory Action Research (PAR. Finally, it addresses the need to link the results to low-income communities, within the concepts of the “new rurality”.

  7. Smeared crack modelling approach for corrosion-induced concrete damage

    DEFF Research Database (Denmark)

    Thybo, Anna Emilie Anusha; Michel, Alexander; Stang, Henrik

    2017-01-01

    In this paper a smeared crack modelling approach is used to simulate corrosion-induced damage in reinforced concrete. The presented modelling approach utilizes a thermal analogy to mimic the expansive nature of solid corrosion products, while taking into account the penetration of corrosion...... products into the surrounding concrete, non-uniform precipitation of corrosion products, and creep. To demonstrate the applicability of the presented modelling approach, numerical predictions in terms of corrosion-induced deformations as well as formation and propagation of micro- and macrocracks were...

  8. Applied Regression Modeling A Business Approach

    CERN Document Server

    Pardoe, Iain

    2012-01-01

    An applied and concise treatment of statistical regression techniques for business students and professionals who have little or no background in calculusRegression analysis is an invaluable statistical methodology in business settings and is vital to model the relationship between a response variable and one or more predictor variables, as well as the prediction of a response value given values of the predictors. In view of the inherent uncertainty of business processes, such as the volatility of consumer spending and the presence of market uncertainty, business professionals use regression a

  9. Jackiw-Pi model: A superfield approach

    Science.gov (United States)

    Gupta, Saurabh

    2014-12-01

    We derive the off-shell nilpotent and absolutely anticommuting Becchi-Rouet-Stora-Tyutin (BRST) as well as anti-BRST transformations s ( a) b corresponding to the Yang-Mills gauge transformations of 3D Jackiw-Pi model by exploiting the "augmented" super-field formalism. We also show that the Curci-Ferrari restriction, which is a hallmark of any non-Abelian 1-form gauge theories, emerges naturally within this formalism and plays an instrumental role in providing the proof of absolute anticommutativity of s ( a) b .

  10. Microdosimetry of electrons in liquid water using the low-energy models of Geant4

    Science.gov (United States)

    Kyriakou, I.; Emfietzoglou, D.; Ivanchenko, V.; Bordage, M. C.; Guatelli, S.; Lazarakis, P.; Tran, H. N.; Incerti, S.

    2017-07-01

    The biological effects of ionizing radiation at the cellular level are frequently studied using the well-known formalism of microdosimetry, which provides a quantitative description of the stochastic aspects of energy deposition in irradiated media. Energy deposition can be simulated using Monte Carlo codes, some adopting a computationally efficient condensed-history approach, while others follow a more detailed track-structure approach. In this work, we present the simulation of microdosimetry spectra and related quantities (frequency-mean and dose-mean lineal energies) for incident monoenergetic electrons (50 eV-10 keV) in spheres of liquid water with dimensions comparable to the size of biological targets: base pairs (2 nm diameter), nucleosomes (10 nm), chromatin fibres (30 nm) and chromosomes (300 nm). Simulations are performed using the condensed-history low-energy physics models ("Livermore" and "Penelope") and the track-structure Geant4-DNA physics models, available in the Geant4 Monte Carlo simulation toolkit. The spectra are compared and the influence of simulation parameters and different physics models, with emphasis on recent developments, is discussed, underlining the suitability of Geant4-DNA models for microdosimetry simulations. It is further shown that with an appropriate choice of simulation parameters, condensed-history transport may yield reasonable results for sphere sizes as small as a few tens of a nanometer.

  11. THE MODEL OF LINGUISTIC TEACHERS’ COMPETENCY DEVELOPMENT ON DESIGNING MULTIMEDIA ELECTRONIC EDUCATIONAL RESOURCES IN THE MOODLE SYSTEM

    Directory of Open Access Journals (Sweden)

    Anton M. Avramchuk

    2017-10-01

    Full Text Available The article is devoted to the problem of developing the competency of teachers of language disciplines on designing multimedia electronic educational resources in the Moodle system. The concept of "the competence of teachers of language disciplines on designing multimedia electronic educational resources in the Moodle system" is justified and defined. Identified and characterized the components by which the levels of the competency development of teachers of language disciplines on designing multimedia electronic educational resources in the Moodle system should be assessed. Developed a model for the development of the competency of teachers of language disciplines on designing multimedia electronic educational resources in the Moodle system, which is based on the main scientific approaches, used in adult education, and consists of five blocks: target, informative, technological, diagnostic and effective.

  12. A modular approach to numerical human body modeling

    NARCIS (Netherlands)

    Forbes, P.A.; Griotto, G.; Rooij, L. van

    2007-01-01

    The choice of a human body model for a simulated automotive impact scenario must take into account both accurate model response and computational efficiency as key factors. This study presents a "modular numerical human body modeling" approach which allows the creation of a customized human body

  13. Mathematical Modeling in Mathematics Education: Basic Concepts and Approaches

    Science.gov (United States)

    Erbas, Ayhan Kürsat; Kertil, Mahmut; Çetinkaya, Bülent; Çakiroglu, Erdinç; Alacaci, Cengiz; Bas, Sinem

    2014-01-01

    Mathematical modeling and its role in mathematics education have been receiving increasing attention in Turkey, as in many other countries. The growing body of literature on this topic reveals a variety of approaches to mathematical modeling and related concepts, along with differing perspectives on the use of mathematical modeling in teaching and…

  14. Susceptibility and Phase Transitions in the Pseudospin-Electron Model at Weak Coupling

    International Nuclear Information System (INIS)

    Stasyuk, I.V.; Mysakovych, T.S.

    2003-01-01

    The pseudospin-electron model (PEM) is considered in the case of the weak pseudospin-electron coupling. It is shown that the transition to uniform and chess-board phases occurs when the chemical potential is situated near the electron band edges and near the band centre, respectively. The incommensurate phase is realized at the intermediate values of the chemical potential. (author)

  15. Implicit moral evaluations: A multinomial modeling approach.

    Science.gov (United States)

    Cameron, C Daryl; Payne, B Keith; Sinnott-Armstrong, Walter; Scheffer, Julian A; Inzlicht, Michael

    2017-01-01

    Implicit moral evaluations-i.e., immediate, unintentional assessments of the wrongness of actions or persons-play a central role in supporting moral behavior in everyday life. Yet little research has employed methods that rigorously measure individual differences in implicit moral evaluations. In five experiments, we develop a new sequential priming measure-the Moral Categorization Task-and a multinomial model that decomposes judgment on this task into multiple component processes. These include implicit moral evaluations of moral transgression primes (Unintentional Judgment), accurate moral judgments about target actions (Intentional Judgment), and a directional tendency to judge actions as morally wrong (Response Bias). Speeded response deadlines reduced Intentional Judgment but not Unintentional Judgment (Experiment 1). Unintentional Judgment was stronger toward moral transgression primes than non-moral negative primes (Experiments 2-4). Intentional Judgment was associated with increased error-related negativity, a neurophysiological indicator of behavioral control (Experiment 4). Finally, people who voted for an anti-gay marriage amendment had stronger Unintentional Judgment toward gay marriage primes (Experiment 5). Across Experiments 1-4, implicit moral evaluations converged with moral personality: Unintentional Judgment about wrong primes, but not negative primes, was negatively associated with psychopathic tendencies and positively associated with moral identity and guilt proneness. Theoretical and practical applications of formal modeling for moral psychology are discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Keyring models: An approach to steerability

    Science.gov (United States)

    Miller, Carl A.; Colbeck, Roger; Shi, Yaoyun

    2018-02-01

    If a measurement is made on one half of a bipartite system, then, conditioned on the outcome, the other half has a new reduced state. If these reduced states defy classical explanation—that is, if shared randomness cannot produce these reduced states for all possible measurements—the bipartite state is said to be steerable. Determining which states are steerable is a challenging problem even for low dimensions. In the case of two-qubit systems, a criterion is known for T-states (that is, those with maximally mixed marginals) under projective measurements. In the current work, we introduce the concept of keyring models—a special class of local hidden state models. When the measurements made correspond to real projectors, these allow us to study steerability beyond T-states. Using keyring models, we completely solve the steering problem for real projective measurements when the state arises from mixing a pure two-qubit state with uniform noise. We also give a partial solution in the case when the uniform noise is replaced by independent depolarizing channels.

  17. A clustering approach to multireference alignment of single-particle projections in electron microscopy.

    Science.gov (United States)

    Sorzano, C O S; Bilbao-Castro, J R; Shkolnisky, Y; Alcorlo, M; Melero, R; Caffarena-Fernández, G; Li, M; Xu, G; Marabini, R; Carazo, J M

    2010-08-01

    Two-dimensional analysis of projections of single-particles acquired by an electron microscope is a useful tool to help identifying the different kinds of projections present in a dataset and their different projection directions. Such analysis is also useful to distinguish between different kinds of particles or different particle conformations. In this paper we introduce a new algorithm for performing two-dimensional multireference alignment and classification that is based on a Hierarchical clustering approach using correntropy (instead of the more traditional correlation) and a modified criterion for the definition of the clusters specially suited for cases in which the Signal-to-Noise Ratio of the differences between classes is low. We show that our algorithm offers an improved sensitivity over current methods in use for distinguishing between different projection orientations and different particle conformations. This algorithm is publicly available through the software package Xmipp. Copyright 2010 Elsevier Inc. All rights reserved.

  18. Reduction of the fast electrons preheating by changing the spike launch time in shock ignition approach

    Science.gov (United States)

    Jafar Jafari, Mohammad; Farahbod, Amir Hossein; Rezaei, Somayeh

    2016-01-01

    Target characteristic parameters in shock ignition approach before launching the spike pulse are studied using a 1-D hydrodynamic simulation code. By delaying the spike launch time, the shell areal density, ρR, is increased. The enhanced shell areal density prevents the hot electrons preheating of main fuel which in turn is generated from the intense laser plasma interaction with corona. To consider the effect of the spike launch time on the target performance, the target gain for a wide range of spike powers and launch times are computed. It is noticed that for HiPER reference target, few tenth nanoseconds displacement of spike launch time increases the areal density, ρR, value up to 30-70 percent. Furthermore, by choosing an appropriate spike energy and peak power, the optimum target gain is achieved in which the total driver energy is reduced.

  19. Stepwise approach to establishing multiple outreach laboratory information system-electronic medical record interfaces

    Directory of Open Access Journals (Sweden)

    Liron Pantanowitz

    2010-01-01

    Full Text Available Clinical laboratory outreach business is changing as more physician practices adopt an electronic medical record (EMR. Physician connectivity with the laboratory information system (LIS is consequently becoming more important. However, there are no reports available to assist the informatician with establishing and maintaining outreach LIS-EMR connectivity. A four-stage scheme is presented that was successfully employed to establish unidirectional and bidirectional interfaces with multiple physician EMRs. This approach involves planning (step 1, followed by interface building (step 2 with subsequent testing (step 3, and finally ongoing maintenance (step 4. The role of organized project management, software as a service (SAAS, and alternate solutions for outreach connectivity are discussed.

  20. Functional RG approach to the Potts model

    Science.gov (United States)

    Ben Alì Zinati, Riccardo; Codello, Alessandro

    2018-01-01

    The critical behavior of the (n+1) -states Potts model in d-dimensions is studied with functional renormalization group techniques. We devise a general method to derive β-functions for continuous values of d and n and we write the flow equation for the effective potential (LPA’) when instead n is fixed. We calculate several critical exponents, which are found to be in good agreement with Monte Carlo simulations and ɛ-expansion results available in the literature. In particular, we focus on Percolation (n\\to0) and Spanning Forest (n\\to-1) which are the only non-trivial universality classes in d  =  4,5 and where our methods converge faster.

  1. Genetic Algorithm Approaches to Prebiobiotic Chemistry Modeling

    Science.gov (United States)

    Lohn, Jason; Colombano, Silvano

    1997-01-01

    We model an artificial chemistry comprised of interacting polymers by specifying two initial conditions: a distribution of polymers and a fixed set of reversible catalytic reactions. A genetic algorithm is used to find a set of reactions that exhibit a desired dynamical behavior. Such a technique is useful because it allows an investigator to determine whether a specific pattern of dynamics can be produced, and if it can, the reaction network found can be then analyzed. We present our results in the context of studying simplified chemical dynamics in theorized protocells - hypothesized precursors of the first living organisms. Our results show that given a small sample of plausible protocell reaction dynamics, catalytic reaction sets can be found. We present cases where this is not possible and also analyze the evolved reaction sets.

  2. Carbonate rock depositional models: A microfacies approach

    Energy Technology Data Exchange (ETDEWEB)

    Carozzi, A.V.

    1988-01-01

    Carbonate rocks contain more than 50% by weight carbonate minerals such as calcite, dolomite, and siderite. Understanding how these rocks form can lead to more efficient methods of petroleum exploration. Micofacies analysis techniques can be used as a method of predicting models of sedimentation for carbonate rocks. Micofacies in carbonate rocks can be seen clearly only in thin sections under a microscope. This section analysis of carbonate rocks is a tool that can be used to understand depositional environments, diagenetic evolution of carbonate rocks, and the formation of porosity and permeability in carbonate rocks. The use of micofacies analysis techniques is applied to understanding the origin and formation of carbonate ramps, carbonate platforms, and carbonate slopes and basins. This book will be of interest to students and professionals concerned with the disciplines of sedimentary petrology, sedimentology, petroleum geology, and palentology.

  3. Wind Turbine Control: Robust Model Based Approach

    DEFF Research Database (Denmark)

    Mirzaei, Mahmood

    . This is because, on the one hand, control methods can decrease the cost of energy by keeping the turbine close to its maximum efficiency. On the other hand, they can reduce structural fatigue and therefore increase the lifetime of the wind turbine. The power produced by a wind turbine is proportional...... to the square of its rotor radius, therefore it seems reasonable to increase the size of the wind turbine in order to capture more power. However as the size increases, the mass of the blades increases by cube of the rotor size. This means in order to keep structural feasibility and mass of the whole structure...... reasonable, the ratio of mass to size should be reduced. This trend results in more flexible structures. Control of the flexible structure of a wind turbine in a wind field with stochastic nature is very challenging. In this thesis we are examining a number of robust model based methods for wind turbine...

  4. Risk prediction model: Statistical and artificial neural network approach

    Science.gov (United States)

    Paiman, Nuur Azreen; Hariri, Azian; Masood, Ibrahim

    2017-04-01

    Prediction models are increasingly gaining popularity and had been used in numerous areas of studies to complement and fulfilled clinical reasoning and decision making nowadays. The adoption of such models assist physician's decision making, individual's behavior, and consequently improve individual outcomes and the cost-effectiveness of care. The objective of this paper is to reviewed articles related to risk prediction model in order to understand the suitable approach, development and the validation process of risk prediction model. A qualitative review of the aims, methods and significant main outcomes of the nineteen published articles that developed risk prediction models from numerous fields were done. This paper also reviewed on how researchers develop and validate the risk prediction models based on statistical and artificial neural network approach. From the review done, some methodological recommendation in developing and validating the prediction model were highlighted. According to studies that had been done, artificial neural network approached in developing the prediction model were more accurate compared to statistical approach. However currently, only limited published literature discussed on which approach is more accurate for risk prediction model development.

  5. The use of an extra-focal electron source to model collimator-scattered electrons using the pencil-beam redefinition algorithm.

    Science.gov (United States)

    Boyd, Robert A; Hogstrom, Kenneth R; White, R Allen; Antolak, John A

    2002-11-01

    Currently, the pencil-beam redefinition algorithm (PBRA) utilizes a single electron source to model clinical electron beams. In the single-source model, the electrons appear to originate from a virtual source located near the scattering foils. Although this approach may be acceptable for most treatment machines, previous studies have shown dose differences as high as 8% relative to the given dose for small fields for some machines such as the Varian Clinac 1800. In such machines collimation-scattered electrons originating from the photon jaws and the applicator give rise to extra-focal electron sources. In this study, we examined the impact of modeling an additional electron source to better account for the collimator-scattered electrons. The desired dose calculation accuracy in water throughout the dose distribution is 3% or better relative to the given dose. We present here a methodology for determining the electron-source parameters for the dual-source model using a minimal set of data, that is, two central-axis depth-dose curves and two off-axis profiles. A Varian Clinac 1800 accelerator was modeled for beam energies of 20 and 9 MeV and applicator sizes of 15 x 15 and 6 x 6 cm2. The improvement in the accuracy of PBRA-calculated dose, evaluated using measured two-dimensional dose distributions in water, was characterized using the figure of merit, FA3%, which represents the fractional area containing dose differences greater than 3%. For the 15 x 15 cm2 field the evaluation was restricted to the penumbral region, and for the 6 x 6 cm2 field the central region of the beam was included as it was impacted by the penumbra. The greatest improvement in dose accuracy was for the 6 x 6 cm2 applicator. At 9 MeV, FA3% decreased from 15% to 0% at 100 cm SSD and from 34% to 4% at 110 cm SSD. At 20 MeV, FA3% decreased from 17% to 2% at 100 cm SSD and from 41% to 10% at 110 cm SSD. In the penumbra of the 15 x 15 cm2 applicator, the improvement was less, but still significant

  6. Challenges of 4D(ata Model for Electronic Government

    Directory of Open Access Journals (Sweden)

    Bogdan GHILIC-MICU

    2015-01-01

    Full Text Available Social evolution pyramid, built on the foundation of the ‘90s capitalist society, lead to the emergence of the informational society – years 1990 to 2005 – and knowledge society – years 2005 to 2020. The literature starts using a new concept, a new form of association – artificial intelligence society – foreseen to be established in the next time frame. All these developments of human society and translations or leaps (most of the times apparently timeless were, are and will be possible only due to the advancing information and communications technologies. The leap to Democracy 3.0, based on information and communication technologies prompts to a radical change in the majority of the classical concepts targeting society structure and the way it is guided and controlled. Thus, concepts become electronic concepts (or e-concepts through the use of new technologies. E-concepts keep the essence of the classical principles of liberty and democracy, adding a major aspect of the new way of communication and spreading ideas between people. The main problem is to quantify, analyze and foresee the way technological changes will influence not only the economic system, but also the daily life of the individual and the society. Unfortunately (or maybe fortunately, depending on the point of view, all these evolutions and technological and social developments are as many challenges for the governments of the world. In this paper we will highlight only four of the challenges facing the governments, grouped in a structured model with the following specific concepts: Big Data, Social Data, Linked Data and Mobile Data. This is an emerging paradigm of the information and communication technology supporting national and global eGovernment projects.

  7. A dual model approach to ground water recovery trench design

    International Nuclear Information System (INIS)

    Clodfelter, C.L.; Crouch, M.S.

    1992-01-01

    The design of trenches for contaminated ground water recovery must consider several variables. This paper presents a dual-model approach for effectively recovering contaminated ground water migrating toward a trench by advection. The approach involves an analytical model to determine the vertical influence of the trench and a numerical flow model to determine the capture zone within the trench and the surrounding aquifer. The analytical model is utilized by varying trench dimensions and head values to design a trench which meets the remediation criteria. The numerical flow model is utilized to select the type of backfill and location of sumps within the trench. The dual-model approach can be used to design a recovery trench which effectively captures advective migration of contaminants in the vertical and horizontal planes

  8. A variational approach to nonsmooth dynamics applications in unilateral mechanics and electronics

    CERN Document Server

    Adly, Samir

    2017-01-01

    This brief examines mathematical models in nonsmooth mechanics and nonregular electrical circuits, including evolution variational inequalities, complementarity systems, differential inclusions, second-order dynamics, Lur'e systems and Moreau's sweeping process. The field of nonsmooth dynamics is of great interest to mathematicians, mechanicians, automatic controllers and engineers. The present volume acknowledges this transversality and provides a multidisciplinary view as it outlines fundamental results in nonsmooth dynamics and explains how to use them to study various problems in engineering. In particular, the author explores the question of how to redefine the notion of dynamical systems in light of modern variational and nonsmooth analysis. With the aim of bridging between the communities of applied mathematicians, engineers and researchers in control theory and nonlinear systems, this brief outlines both relevant mathematical proofs and models in unilateral mechanics and electronics.

  9. A new theoretical model for scattering of electrons by molecules. 1

    International Nuclear Information System (INIS)

    Peixoto, E.M.A.; Mu-tao, L.; Nogueira, J.C.

    1975-01-01

    A new theoretical model for electron-molecule scattering is suggested. The e-H 2 scattering is studied and the superiority of the new model over the commonly used Independent Atom Model (IAM) is demonstrated. Comparing theoretical and experimental data for 40keV electrons scattered by H 2 utilizing the new model, its validity is proved, while Partial Wave and First Born calculations, employing the Independent Atom Model, strongly deviated from the experiment [pt

  10. Modeling and Design of GaN High Electron Mobility Transistors and Hot Electron Transistors through Monte Carlo Particle-based Device Simulations

    Science.gov (United States)

    Soligo, Riccardo

    In this work, the insight provided by our sophisticated Full Band Monte Carlo simulator is used to analyze the behavior of state-of-art devices like GaN High Electron Mobility Transistors and Hot Electron Transistors. Chapter 1 is dedicated to the description of the simulation tool used to obtain the results shown in this work. Moreover, a separate section is dedicated the set up of a procedure to validate to the tunneling algorithm recently implemented in the simulator. Chapter 2 introduces High Electron Mobility Transistors (HEMTs), state-of-art devices characterized by highly non linear transport phenomena that require the use of advanced simulation methods. The techniques for device modeling are described applied to a recent GaN-HEMT, and they are validated with experimental measurements. The main techniques characterization techniques are also described, including the original contribution provided by this work. Chapter 3 focuses on a popular technique to enhance HEMTs performance: the down-scaling of the device dimensions. In particular, this chapter is dedicated to lateral scaling and the calculation of a limiting cutoff frequency for a device of vanishing length. Finally, Chapter 4 and Chapter 5 describe the modeling of Hot Electron Transistors (HETs). The simulation approach is validated by matching the current characteristics with the experimental one before variations of the layouts are proposed to increase the current gain to values suitable for amplification. The frequency response of these layouts is calculated, and modeled by a small signal circuit. For this purpose, a method to directly calculate the capacitance is developed which provides a graphical picture of the capacitative phenomena that limit the frequency response in devices. In Chapter 5 the properties of the hot electrons are investigated for different injection energies, which are obtained by changing the layout of the emitter barrier. Moreover, the large signal characterization of the

  11. Modeling disease severity in multiple sclerosis using electronic health records.

    Directory of Open Access Journals (Sweden)

    Zongqi Xia

    Full Text Available To optimally leverage the scalability and unique features of the electronic health records (EHR for research that would ultimately improve patient care, we need to accurately identify patients and extract clinically meaningful measures. Using multiple sclerosis (MS as a proof of principle, we showcased how to leverage routinely collected EHR data to identify patients with a complex neurological disorder and derive an important surrogate measure of disease severity heretofore only available in research settings.In a cross-sectional observational study, 5,495 MS patients were identified from the EHR systems of two major referral hospitals using an algorithm that includes codified and narrative information extracted using natural language processing. In the subset of patients who receive neurological care at a MS Center where disease measures have been collected, we used routinely collected EHR data to extract two aggregate indicators of MS severity of clinical relevance multiple sclerosis severity score (MSSS and brain parenchymal fraction (BPF, a measure of whole brain volume.The EHR algorithm that identifies MS patients has an area under the curve of 0.958, 83% sensitivity, 92% positive predictive value, and 89% negative predictive value when a 95% specificity threshold is used. The correlation between EHR-derived and true MSSS has a mean R(2 = 0.38±0.05, and that between EHR-derived and true BPF has a mean R(2 = 0.22±0.08. To illustrate its clinical relevance, derived MSSS captures the expected difference in disease severity between relapsing-remitting and progressive MS patients after adjusting for sex, age of symptom onset and disease duration (p = 1.56×10(-12.Incorporation of sophisticated codified and narrative EHR data accurately identifies MS patients and provides estimation of a well-accepted indicator of MS severity that is widely used in research settings but not part of the routine medical records. Similar approaches

  12. Basic Equations for the Modeling of Gallium Nitride (gan) High Electron Mobility Transistors (hemts)

    Science.gov (United States)

    Freeman, Jon C.

    2003-01-01

    Gallium nitride (GaN) is a most promising wide band-gap semiconductor for use in high-power microwave devices. It has functioned at 320 C, and higher values are well within theoretical limits. By combining four devices, 20 W has been developed at X-band. GaN High Electron Mobility Transistors (HEMTs) are unique in that the two-dimensional electron gas (2DEG) is supported not by intentional doping, but instead by polarization charge developed at the interface between the bulk GaN region and the AlGaN epitaxial layer. The polarization charge is composed of two parts: spontaneous and piezoelectric. This behavior is unlike other semiconductors, and for that reason, no commercially available modeling software exists. The theme of this document is to develop a self-consistent approach to developing the pertinent equations to be solved. A Space Act Agreement, "Effects in AlGaN/GaN HEMT Semiconductors" with Silvaco Data Systems to implement this approach into their existing software for III-V semiconductors, is in place (summer of 2002).

  13. EDUCATIONAL COMPLEX ON ELECTRICAL ENGINEERING AND ELECTRONICS BASED ON MODELING IN PROGRAM TINA

    Directory of Open Access Journals (Sweden)

    Vladimir A. Alekhin

    2014-01-01

    Full Text Available The educational complex on the electrical engineering and electronics has been developed. It contains a course of lectures and lecture notes in the electronic form, a new computer laboratory practical work and practical training. All electronic manuals are based on modeling of electric and electronic circuits in the new effective program TINA. The educational complex is being successfully used in educational process on internal and distant learning. 

  14. Simple queueing approach to segregation dynamics in Schelling model

    OpenAIRE

    Sobkowicz, Pawel

    2007-01-01

    A simple queueing approach for segregation of agents in modified one dimensional Schelling segregation model is presented. The goal is to arrive at simple formula for the number of unhappy agents remaining after the segregation.

  15. Virtuous organization: A structural equation modeling approach

    Directory of Open Access Journals (Sweden)

    Majid Zamahani

    2013-02-01

    Full Text Available For years, the idea of virtue was unfavorable among researchers and virtues were traditionally considered as culture-specific, relativistic and they were supposed to be associated with social conservatism, religious or moral dogmatism, and scientific irrelevance. Virtue and virtuousness have been recently considered seriously among organizational researchers. The proposed study of this paper examines the relationships between leadership, organizational culture, human resource, structure and processes, care for community and virtuous organization. Structural equation modeling is employed to investigate the effects of each variable on other components. The data used in this study consists of questionnaire responses from employees in Payam e Noor University in Yazd province. A total of 250 questionnaires were sent out and a total of 211 valid responses were received. Our results have revealed that all the five variables have positive and significant impacts on virtuous organization. Among the five variables, organizational culture has the most direct impact (0.80 and human resource has the most total impact (0.844 on virtuous organization.

  16. A systemic approach for modeling soil functions

    Science.gov (United States)

    Vogel, Hans-Jörg; Bartke, Stephan; Daedlow, Katrin; Helming, Katharina; Kögel-Knabner, Ingrid; Lang, Birgit; Rabot, Eva; Russell, David; Stößel, Bastian; Weller, Ulrich; Wiesmeier, Martin; Wollschläger, Ute

    2018-03-01

    The central importance of soil for the functioning of terrestrial systems is increasingly recognized. Critically relevant for water quality, climate control, nutrient cycling and biodiversity, soil provides more functions than just the basis for agricultural production. Nowadays, soil is increasingly under pressure as a limited resource for the production of food, energy and raw materials. This has led to an increasing demand for concepts assessing soil functions so that they can be adequately considered in decision-making aimed at sustainable soil management. The various soil science disciplines have progressively developed highly sophisticated methods to explore the multitude of physical, chemical and biological processes in soil. It is not obvious, however, how the steadily improving insight into soil processes may contribute to the evaluation of soil functions. Here, we present to a new systemic modeling framework that allows for a consistent coupling between reductionist yet observable indicators for soil functions with detailed process understanding. It is based on the mechanistic relationships between soil functional attributes, each explained by a network of interacting processes as derived from scientific evidence. The non-linear character of these interactions produces stability and resilience of soil with respect to functional characteristics. We anticipate that this new conceptional framework will integrate the various soil science disciplines and help identify important future research questions at the interface between disciplines. It allows the overwhelming complexity of soil systems to be adequately coped with and paves the way for steadily improving our capability to assess soil functions based on scientific understanding.

  17. A Constructive Neural-Network Approach to Modeling Psychological Development

    Science.gov (United States)

    Shultz, Thomas R.

    2012-01-01

    This article reviews a particular computational modeling approach to the study of psychological development--that of constructive neural networks. This approach is applied to a variety of developmental domains and issues, including Piagetian tasks, shift learning, language acquisition, number comparison, habituation of visual attention, concept…

  18. Towards Translating Graph Transformation Approaches by Model Transformations

    NARCIS (Netherlands)

    Hermann, F.; Kastenberg, H.; Modica, T.; Karsai, G.; Taentzer, G.

    2006-01-01

    Recently, many researchers are working on semantics preserving model transformation. In the field of graph transformation one can think of translating graph grammars written in one approach to a behaviourally equivalent graph grammar in another approach. In this paper we translate graph grammars

  19. An Almost Integration-free Approach to Ordered Response Models

    NARCIS (Netherlands)

    van Praag, B.M.S.; Ferrer-i-Carbonell, A.

    2006-01-01

    'In this paper we propose an alternative approach to the estimation of ordered response models. We show that the Probit-method may be replaced by a simple OLS-approach, called P(robit)OLS, without any loss of efficiency. This method can be generalized to the analysis of panel data. For large-scale

  20. Optimizing technology investments: a broad mission model approach

    Science.gov (United States)

    Shishko, R.

    2003-01-01

    A long-standing problem in NASA is how to allocate scarce technology development resources across advanced technologies in order to best support a large set of future potential missions. Within NASA, two orthogonal paradigms have received attention in recent years: the real-options approach and the broad mission model approach. This paper focuses on the latter.

  1. A generalized quarter car modelling approach with frame flexibility ...

    Indian Academy of Sciences (India)

    ... mass distribution and damping. Here we propose a generalized quarter-car modelling approach, incorporating both the frame as well as other-wheel ground contacts. Our approach is linear, uses Laplace transforms, involves vertical motions of key points of interest and has intermediate complexity with improved realism.

  2. Electronic Modeling and Design for Extreme Temperatures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop electronics for operation at temperatures that range from -230oC to +130oC. This new technology will minimize the requirements for external...

  3. Electronic Modeling and Design for Extreme Temperatures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop electronics for operation at temperatures that range from -230oC to +130oC. This new technology will minimize the requirements for external...

  4. New two-fluid (localized + band electron) model for manganites

    Indian Academy of Sciences (India)

    Two types of eg electronic states arise in doped manganites (due to strong JT coupling, strong U, filling conditions, …): Localized, with JT distortion, do not hop; Without distortion, hop and form a band ...

  5. Modeling of the interaction of an x-ray free-electron laser with large finite samples

    Science.gov (United States)

    Peyrusse, O.; André, J.-M.; Jonnard, P.; Gaudin, J.

    2017-10-01

    We describe a model for the study of the interaction of short x-ray free-electron laser (XFEL) pulses with large finite samples. Hydrodynamics is solved in one-dimensional planar geometry with consideration of the electron-ion energy exchange and of the possible elastoplastic behavior. From a time-dependent calculation of the complex refractive index and of the underlying atomic physics, XFEL energy deposition is modeled through a calculation of the radiation field in the material. In the case of hard x-ray irradiation, energetic electrons induced by the XFEL absorption can propagate and deposit their energy outside the interaction region. Simulations of the interaction of hard x-ray ultrashort pulses with solid materials Ru and Si at different grazing incidence angles are presented and discussed. The results obtained demonstrate the potential of this approach to predict damage dynamics for materials of interest for x-ray optics.

  6. A Comparative Study of Spectral Auroral Intensity Predictions From Multiple Electron Transport Models

    Science.gov (United States)

    Grubbs, Guy; Michell, Robert; Samara, Marilia; Hampton, Donald; Hecht, James; Solomon, Stanley; Jahn, Jorg-Micha

    2018-01-01

    It is important to routinely examine and update models used to predict auroral emissions resulting from precipitating electrons in Earth's magnetotail. These models are commonly used to invert spectral auroral ground-based images to infer characteristics about incident electron populations when in situ measurements are unavailable. In this work, we examine and compare auroral emission intensities predicted by three commonly used electron transport models using varying electron population characteristics. We then compare model predictions to same-volume in situ electron measurements and ground-based imaging to qualitatively examine modeling prediction error. Initial comparisons showed differences in predictions by the GLobal airglOW (GLOW) model and the other transport models examined. Chemical reaction rates and radiative rates in GLOW were updated using recent publications, and predictions showed better agreement with the other models and the same-volume data, stressing that these rates are important to consider when modeling auroral processes. Predictions by each model exhibit similar behavior for varying atmospheric constants, energies, and energy fluxes. Same-volume electron data and images are highly correlated with predictions by each model, showing that these models can be used to accurately derive electron characteristics and ionospheric parameters based solely on multispectral optical imaging data.

  7. Modelling of pathologies of the nervous system by the example of computational and electronic models of elementary nervous systems

    International Nuclear Information System (INIS)

    Shumilov, V. N.; Syryamkin, V. I.; Syryamkin, M. V.

    2015-01-01

    The paper puts forward principles of action of devices operating similarly to the nervous system and the brain of biological systems. We propose an alternative method of studying diseases of the nervous system, which may significantly influence prevention, medical treatment, or at least retardation of development of these diseases. This alternative is to use computational and electronic models of the nervous system. Within this approach, we represent the brain in the form of a huge electrical circuit composed of active units, namely, neuron-like units and connections between them. As a result, we created computational and electronic models of elementary nervous systems, which are based on the principles of functioning of biological nervous systems that we have put forward. Our models demonstrate reactions to external stimuli and their change similarly to the behavior of simplest biological organisms. The models possess the ability of self-training and retraining in real time without human intervention and switching operation/training modes. In our models, training and memorization take place constantly under the influence of stimuli on the organism. Training is without any interruption and switching operation modes. Training and formation of new reflexes occur by means of formation of new connections between excited neurons, between which formation of connections is physically possible. Connections are formed without external influence. They are formed under the influence of local causes. Connections are formed between outputs and inputs of two neurons, when the difference between output and input potentials of excited neurons exceeds a value sufficient to form a new connection. On these grounds, we suggest that the proposed principles truly reflect mechanisms of functioning of biological nervous systems and the brain. In order to confirm the correspondence of the proposed principles to biological nature, we carry out experiments for the study of processes of

  8. Modelling of pathologies of the nervous system by the example of computational and electronic models of elementary nervous systems

    Energy Technology Data Exchange (ETDEWEB)

    Shumilov, V. N., E-mail: vnshumilov@rambler.ru; Syryamkin, V. I., E-mail: maximus70sir@gmail.com; Syryamkin, M. V., E-mail: maximus70sir@gmail.com [National Research Tomsk State University, 634050, Tomsk, Lenin Avenue, 36 (Russian Federation)

    2015-11-17

    The paper puts forward principles of action of devices operating similarly to the nervous system and the brain of biological systems. We propose an alternative method of studying diseases of the nervous system, which may significantly influence prevention, medical treatment, or at least retardation of development of these diseases. This alternative is to use computational and electronic models of the nervous system. Within this approach, we represent the brain in the form of a huge electrical circuit composed of active units, namely, neuron-like units and connections between them. As a result, we created computational and electronic models of elementary nervous systems, which are based on the principles of functioning of biological nervous systems that we have put forward. Our models demonstrate reactions to external stimuli and their change similarly to the behavior of simplest biological organisms. The models possess the ability of self-training and retraining in real time without human intervention and switching operation/training modes. In our models, training and memorization take place constantly under the influence of stimuli on the organism. Training is without any interruption and switching operation modes. Training and formation of new reflexes occur by means of formation of new connections between excited neurons, between which formation of connections is physically possible. Connections are formed without external influence. They are formed under the influence of local causes. Connections are formed between outputs and inputs of two neurons, when the difference between output and input potentials of excited neurons exceeds a value sufficient to form a new connection. On these grounds, we suggest that the proposed principles truly reflect mechanisms of functioning of biological nervous systems and the brain. In order to confirm the correspondence of the proposed principles to biological nature, we carry out experiments for the study of processes of

  9. Electron injector for high-voltage model of collective accelerator

    International Nuclear Information System (INIS)

    Belikov, V.V.; Zvyagintsev, A.V.; Lymar', A.G.; Martynenko, P.A.; Khizhnyak, N.A.

    1987-01-01

    The design and test results of an electron gun with the beam compression and axial hole aimed at collective acceleration are presented. The electron gun is tested at 150 kV, the pulse duration being 12 ms. The hallow beam has 10 mm in diameter, with 1 mm thick wall, that corresponds to the compression degree of 200. The beam microperveance is 4.5 mA/V 3/2

  10. Numerical approaches to expansion process modeling

    Directory of Open Access Journals (Sweden)

    G. V. Alekseev

    2017-01-01

    Full Text Available Forage production is currently undergoing a period of intensive renovation and introduction of the most advanced technologies and equipment. More and more often such methods as barley toasting, grain extrusion, steaming and grain flattening, boiling bed explosion, infrared ray treatment of cereals and legumes, followed by flattening, and one-time or two-time granulation of the purified whole grain without humidification in matrix presses By grinding the granules. These methods require special apparatuses, machines, auxiliary equipment, created on the basis of different methods of compiled mathematical models. When roasting, simulating the heat fields arising in the working chamber, provide such conditions, the decomposition of a portion of the starch to monosaccharides, which makes the grain sweetish, but due to protein denaturation the digestibility of the protein and the availability of amino acids decrease somewhat. Grain is roasted mainly for young animals in order to teach them to eat food at an early age, stimulate the secretory activity of digestion, better development of the masticatory muscles. In addition, the high temperature is detrimental to bacterial contamination and various types of fungi, which largely avoids possible diseases of the gastrointestinal tract. This method has found wide application directly on the farms. Apply when used in feeding animals and legumes: peas, soy, lupine and lentils. These feeds are preliminarily ground, and then cooked or steamed for 1 hour for 30–40 minutes. In the feed mill. Such processing of feeds allows inactivating the anti-nutrients in them, which reduce the effectiveness of their use. After processing, legumes are used as protein supplements in an amount of 25–30% of the total nutritional value of the diet. But it is recommended to cook and steal a grain of good quality. A poor-quality grain that has been stored for a long time and damaged by pathogenic micro flora is subject to

  11. Graphical approach to model reduction for nonlinear biochemical networks.

    Science.gov (United States)

    Holland, David O; Krainak, Nicholas C; Saucerman, Jeffrey J

    2011-01-01

    Model reduction is a central challenge to the development and analysis of multiscale physiology models. Advances in model reduction are needed not only for computational feasibility but also for obtaining conceptual insights from complex systems. Here, we introduce an intuitive graphical approach to model reduction based on phase plane analysis. Timescale separation is identified by the degree of hysteresis observed in phase-loops, which guides a "concentration-clamp" procedure for estimating explicit algebraic relationships between species equilibrating on fast timescales. The primary advantages of this approach over Jacobian-based timescale decomposition are that: 1) it incorporates nonlinear system dynamics, and 2) it can be easily visualized, even directly from experimental data. We tested this graphical model reduction approach using a 25-variable model of cardiac β(1)-adrenergic signaling, obtaining 6- and 4-variable reduced models that retain good predictive capabilities even in response to new perturbations. These 6 signaling species appear to be optimal "kinetic biomarkers" of the overall β(1)-adrenergic pathway. The 6-variable reduced model is well suited for integration into multiscale models of heart function, and more generally, this graphical model reduction approach is readily applicable to a variety of other complex biological systems.

  12. Graphical approach to model reduction for nonlinear biochemical networks.

    Directory of Open Access Journals (Sweden)

    David O Holland

    Full Text Available Model reduction is a central challenge to the development and analysis of multiscale physiology models. Advances in model reduction are needed not only for computational feasibility but also for obtaining conceptual insights from complex systems. Here, we introduce an intuitive graphical approach to model reduction based on phase plane analysis. Timescale separation is identified by the degree of hysteresis observed in phase-loops, which guides a "concentration-clamp" procedure for estimating explicit algebraic relationships between species equilibrating on fast timescales. The primary advantages of this approach over Jacobian-based timescale decomposition are that: 1 it incorporates nonlinear system dynamics, and 2 it can be easily visualized, even directly from experimental data. We tested this graphical model reduction approach using a 25-variable model of cardiac β(1-adrenergic signaling, obtaining 6- and 4-variable reduced models that retain good predictive capabilities even in response to new perturbations. These 6 signaling species appear to be optimal "kinetic biomarkers" of the overall β(1-adrenergic pathway. The 6-variable reduced model is well suited for integration into multiscale models of heart function, and more generally, this graphical model reduction approach is readily applicable to a variety of other complex biological systems.

  13. Reconstructive approaches to one- and two-electron density matrix theory

    Science.gov (United States)

    Herbert, John Michael

    Novel computational methods for electronic structure theory are explored, in which the fundamental variable is either the one- or the two-electron reduced density matrix (1- or 2-RDM), rather than the electronic wavefunction. A unifying theme among these methods is density matrix reconstruction, that is, decoupling approximations that express higher-order density matrices as functionals of lower-order ones. On the 2-RDM side, a connected (extensive) version of the Contracted Schrodinger Equation (CSE) is developed, in which the basic unknowns are the RDM cumulants through order four. Reconstruction functionals that neglect the 3- and 4-RDM cumulants are examined and revealed to be significantly less accurate than suggested by previous minimal-basis results. Exact 3-RDM cumulants for some four-electron systems are calculated and found to be comparable in importance to unconnected products of lower-order cumulants. Decoupling approximations for the 3- and 4-RDM cumulants are developed based upon a renormalized, diagrammatic perturbation theory for the three- and four-particle Green's functions, in which the effective, pairwise interaction is extracted from the two-particle cumulant. Diagram rules suitable for both the time-dependent and time-independent versions of this perturbation theory are derived. Reconstructive approaches to natural orbital (1-RDM) functional theory are also examined, wherein the 2-RDM is parametrized in terms of the natural orbitals and their (generally fractional) occupancies. It is demonstrated, at the theorem level, that proposed "corrected Hartree" and "corrected Hartree-Fock" natural orbital functionals necessarily violate positivity of the 2-RDM, which is closely related to their failure to respect antisymmetry. Calculations demonstrate that negative eigenvalues of the 2-RDM are associated with a large, stabilizing (but ultimately spurious) contribution to the energy. Nevertheless, a partially self-interaction-corrected version of the

  14. Data Analysis A Model Comparison Approach, Second Edition

    CERN Document Server

    Judd, Charles M; Ryan, Carey S

    2008-01-01

    This completely rewritten classic text features many new examples, insights and topics including mediational, categorical, and multilevel models. Substantially reorganized, this edition provides a briefer, more streamlined examination of data analysis. Noted for its model-comparison approach and unified framework based on the general linear model, the book provides readers with a greater understanding of a variety of statistical procedures. This consistent framework, including consistent vocabulary and notation, is used throughout to develop fewer but more powerful model building techniques. T

  15. A Model Management Approach for Co-Simulation Model Evaluation

    NARCIS (Netherlands)

    Zhang, X.C.; Broenink, Johannes F.; Filipe, Joaquim; Kacprzyk, Janusz; Pina, Nuno

    2011-01-01

    Simulating formal models is a common means for validating the correctness of the system design and reduce the time-to-market. In most of the embedded control system design, multiple engineering disciplines and various domain-specific models are often involved, such as mechanical, control, software

  16. EPR policies for electronics in developing Asia: an adapted phase-in approach.

    Science.gov (United States)

    Akenji, Lewis; Hotta, Yasuhiko; Bengtsson, Magnus; Hayashi, Shiko

    2011-09-01

    The amount of e-waste is growing rapidly in developing countries, and the health and environmental problems resulting from poor management of this waste have become a concern for policy makers. In response to these challenges, a number of Asian developing countries have been inspired by policy developments in OECD countries, and have drafted legislations based on the principle of extended producer responsibility (EPR). However, the experiences from developed countries show that a successful implementation of EPR policies requires adequate institutions and sufficient administrative capacity. Even advanced countries are thus facing difficulties. This paper concludes from existing literature and from the authors' own observations that there seems to be a mismatch between the typical policy responses to e-waste problems in developing Asia and the capacity for successful implementation of such policies. It also notes that the e-waste situation in developing Asian countries is further complicated by a number of additional factors, such as difficulties in identifying producers, import of used electronic products and e-waste (sometimes illegal), and the existence of a strong informal waste sector. Given these challenges, the authors conclude that comprehensive EPR policy schemes of the kind that have been implemented in some advanced countries are not likely to be effective. The paper therefore proposes an alternative phase-in approach whereby developing Asian countries are able to move gradually towards EPR systems. It argues that this approach would be more feasible, and discusses what could be the key building blocks of each implementation stage.

  17. A novel system architecture for the national integration of electronic health records: a semi-centralized approach.

    Science.gov (United States)

    AlJarullah, Asma; El-Masri, Samir

    2013-08-01

    The goal of a national electronic health records integration system is to aggregate electronic health records concerning a particular patient at different healthcare providers' systems to provide a complete medical history of the patient. It holds the promise to address the two most crucial challenges to the healthcare systems: improving healthcare quality and controlling costs. Typical approaches for the national integration of electronic health records are a centralized architecture and a distributed architecture. This paper proposes a new approach for the national integration of electronic health records, the semi-centralized approach, an intermediate solution between the centralized architecture and the distributed architecture that has the benefits of both approaches. The semi-centralized approach is provided with a clearly defined architecture. The main data elements needed by the system are defined and the main system modules that are necessary to achieve an effective and efficient functionality of the system are designed. Best practices and essential requirements are central to the evolution of the proposed architecture. The proposed architecture will provide the basis for designing the simplest and the most effective systems to integrate electronic health records on a nation-wide basis that maintain integrity and consistency across locations, time and systems, and that meet the challenges of interoperability, security, privacy, maintainability, mobility, availability, scalability, and load balancing.

  18. Engine modeling and control modeling and electronic management of internal combustion engines

    CERN Document Server

    Isermann, Rolf

    2014-01-01

    The increasing demands for internal combustion engines with regard to fuel consumption, emissions and driveability lead to more actuators, sensors and complex control functions. A systematic implementation of the electronic control systems requires mathematical models from basic design through simulation to calibration. The book treats physically-based as well as models based experimentally on test benches for gasoline (spark ignition) and diesel (compression ignition) engines and uses them for the design of the different control functions. The main topics are: - Development steps for engine control - Stationary and dynamic experimental modeling - Physical models of intake, combustion, mechanical system, turbocharger, exhaust, cooling, lubrication, drive train - Engine control structures, hardware, software, actuators, sensors, fuel supply, injection system, camshaft - Engine control methods, static and dynamic feedforward and feedback control, calibration and optimization, HiL, RCP, control software developm...

  19. A multidisciplinary approach to designing and evaluating Electronic Medical Record portal messages that support patient self-care.

    Science.gov (United States)

    Morrow, Daniel; Hasegawa-Johnson, Mark; Huang, Thomas; Schuh, William; Azevedo, Renato Ferreira Leitão; Gu, Kuangxiao; Zhang, Yang; Roy, Bidisha; Garcia-Retamero, Rocio

    2017-05-01

    We describe a project intended to improve the use of Electronic Medical Record (EMR) patient portal information by older adults with diverse numeracy and literacy abilities, so that portals can better support patient-centered care. Patient portals are intended to bridge patients and providers by ensuring patients have continuous access to their health information and services. However, they are underutilized, especially by older adults with low health literacy, because they often function more as information repositories than as tools to engage patients. We outline an interdisciplinary approach to designing and evaluating portal-based messages that convey clinical test results so as to support patient-centered care. We first describe a theory-based framework for designing effective messages for patients. This involves analyzing shortcomings of the standard portal message format (presenting numerical test results with little context to guide comprehension) and developing verbally, graphically, video- and computer agent-based formats that enhance context. The framework encompasses theories from cognitive and behavioral science (health literacy, fuzzy trace memory, behavior change) as well as computational/engineering approaches (e.g., image and speech processing models). We then describe an approach to evaluating whether the formats improve comprehension of and responses to the messages about test results, focusing on our methods. The approach combines quantitative (e.g., response accuracy, Likert scale responses) and qualitative (interview) measures, as well as experimental and individual difference methods in order to investigate which formats are more effective, and whether some formats benefit some types of patients more than others. We also report the results of two pilot studies conducted as part of developing the message formats. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Using a matter wave model to study the structure of the electron inside an atom

    Science.gov (United States)

    Chang, Donald

    In Bohr's atomic model, the atom was conceptually modeled as a miniature solar system. With the development of the Schrödinger equation, the wave function of the electron inside an atom becomes much better known. But the electron is still regarded as a pointed object; according to the Copenhagen Interpretation, the wave function is thought to describe only the probability of finding the electron. Such an interpretation, however, has raised some conceptual questions. For example, how can a point-like electron form a chemical bond between neighboring atoms? In an attempt to overcome this difficulty, we use a matter wave theory to model the structure of an electron inside the atom. This model is inspired by noticing the similarity between a free electron and a photon; both particles behave like a corpuscular object as well as a physical wave. Thus, we hypothesize that, like the photon, an electron is an excitation wave of a real physical field. Based on this hypothesis, we have derived a basic wave equation for the free electron. We show that, in the presence of an electrical potential, this basic wave equation can lead to the Schrödinger equation. This work implies that the solution of the Schrödinger equation actually represents the physical waves of the electron. Thus, the electron inside the atom should behave more like a topologically distributive wave than a pointed object. In this presentation, we will discuss the advantages and limitations of this model.