Rolland, N; Larson, D J; Geiser, B P; Duguay, S; Vurpillot, F; Blavette, D
2015-12-01
An analytical model describing the field evaporation dynamics of a tip made of a thin layer deposited on a substrate is presented in this paper. The difference in evaporation field between the materials is taken into account in this approach in which the tip shape is modeled at a mesoscopic scale. It was found that the non-existence of sharp edge on the surface is a sufficient condition to derive the morphological evolution during successive evaporation of the layers. This modeling gives an instantaneous and smooth analytical representation of the surface that shows good agreement with finite difference simulations results, and a specific regime of evaporation was highlighted when the substrate is a low evaporation field phase. In addition, the model makes it possible to calculate theoretically the tip analyzed volume, potentially opening up new horizons for atom probe tomographic reconstruction. Copyright © 2015 Elsevier B.V. All rights reserved.
Model for resonant plasma probe.
Energy Technology Data Exchange (ETDEWEB)
Warne, Larry Kevin; Johnson, William Arthur; Hebner, Gregory Albert; Jorgenson, Roy E.; Coats, Rebecca Sue
2007-04-01
This report constructs simple circuit models for a hairpin shaped resonant plasma probe. Effects of the plasma sheath region surrounding the wires making up the probe are determined. Electromagnetic simulations of the probe are compared to the circuit model results. The perturbing effects of the disc cavity in which the probe operates are also found.
Nucleic acid-based fluorescent probes and their analytical potential.
Juskowiak, Bernard
2011-03-01
It is well known that nucleic acids play an essential role in living organisms because they store and transmit genetic information and use that information to direct the synthesis of proteins. However, less is known about the ability of nucleic acids to bind specific ligands and the application of oligonucleotides as molecular probes or biosensors. Oligonucleotide probes are single-stranded nucleic acid fragments that can be tailored to have high specificity and affinity for different targets including nucleic acids, proteins, small molecules, and ions. One can divide oligonucleotide-based probes into two main categories: hybridization probes that are based on the formation of complementary base-pairs, and aptamer probes that exploit selective recognition of nonnucleic acid analytes and may be compared with immunosensors. Design and construction of hybridization and aptamer probes are similar. Typically, oligonucleotide (DNA, RNA) with predefined base sequence and length is modified by covalent attachment of reporter groups (one or more fluorophores in fluorescence-based probes). The fluorescent labels act as transducers that transform biorecognition (hybridization, ligand binding) into a fluorescence signal. Fluorescent labels have several advantages, for example high sensitivity and multiple transduction approaches (fluorescence quenching or enhancement, fluorescence anisotropy, fluorescence lifetime, fluorescence resonance energy transfer (FRET), and excimer-monomer light switching). These multiple signaling options combined with the design flexibility of the recognition element (DNA, RNA, PNA, LNA) and various labeling strategies contribute to development of numerous selective and sensitive bioassays. This review covers fundamentals of the design and engineering of oligonucleotide probes, describes typical construction approaches, and discusses examples of probes used both in hybridization studies and in aptamer-based assays.
Analytic Modeling of Insurgencies
2014-08-01
literature , e.g., [9], [24]. Modeling public behavior takes into account the difference between the attitude of an individual (his “heart”) and his...vol. 10, pp. 818- 827, 1962. [4] G. McCormick, "The Shining Path and Peruvian terrorism," RAND, P-7297, Santa Monica, CA, 1987. [5] B. Connable, W
Predictive analytics can support the ACO model.
Bradley, Paul
2012-04-01
Predictive analytics can be used to rapidly spot hard-to-identify opportunities to better manage care--a key tool in accountable care. When considering analytics models, healthcare providers should: Make value-based care a priority and act on information from analytics models. Create a road map that includes achievable steps, rather than major endeavors. Set long-term expectations and recognize that the effectiveness of an analytics program takes time, unlike revenue cycle initiatives that may show a quick return.
Calibration models for high enthalpy calorimetric probes.
Kannel, A
1978-07-01
The accuracy of gas-aspirated liquid-cooled calorimetric probes used for measuring the enthalpy of high-temperature gas streams is studied. The error in the differential temperature measurements caused by internal and external heat transfer interactions is considered and quantified by mathematical models. The analysis suggests calibration methods for the evaluation of dimensionless heat transfer parameters in the models, which then can give a more accurate value for the enthalpy of the sample. Calibration models for four types of calorimeters are applied to results from the literature and from our own experiments: a circular slit calorimeter developed by the author, single-cooling jacket probe, double-cooling jacket probe, and split-flow cooling jacket probe. The results show that the models are useful for describing and correcting the temperature measurements.
In Situ Scanning Probe Microscopy and New Perspectives in Analytical Chemistry
DEFF Research Database (Denmark)
Andersen, Jens Enevold Thaulov; Zhang, Jingdong; Chi, Qijin
1999-01-01
The resolution of scanning probe microscopies is unpresedented but the techniques are fraught with limitations as analytical tools. These limitations and their relationship to the physical mechanisms of image contrast are first discussed. Some new options based on in situ STM, which hold prospect...
Analytical methods used at model facility
International Nuclear Information System (INIS)
Wing, N.S.
1984-01-01
A description of analytical methods used at the model LEU Fuel Fabrication Facility is presented. The methods include gravimetric uranium analysis, isotopic analysis, fluorimetric analysis, and emission spectroscopy
Modeling Atom Probe Tomography: A review
Energy Technology Data Exchange (ETDEWEB)
Vurpillot, F., E-mail: francois.vurpillot@univ-rouen.fr [Groupe de Physique des Matériaux, UMR CNRS 6634, Université de Rouen, Saint Etienne du Rouvray 76801 (France); Oberdorfer, C. [Institut für Materialwissenschaft, Lehrstuhl für Materialphysik, Universität Stuttgart, Heisenbergstr. 3, 70569 Stuttgart (Germany)
2015-12-15
Improving both the precision and the accuracy of Atom Probe Tomography reconstruction requires a correct understanding of the imaging process. In this aim, numerical modeling approaches have been developed for 15 years. The injected ingredients of these modeling tools are related to the basic physic of the field evaporation mechanism. The interplay between the sample nature and structure of the analyzed sample and the reconstructed image artefacts have pushed to gradually improve and make the model more and more sophisticated. This paper reviews the evolution of the modeling approach in Atom Probe Tomography and presents some future potential directions in order to improve the method. - Highlights: • The basics of field evaporation. • The main aspects of Atom Probe Tomography modeling. • The intrinsic limitations of the current method and future potential directions to improve the understanding of tip to image ion projection.
Modeling Atom Probe Tomography: A review.
Vurpillot, F; Oberdorfer, C
2015-12-01
Improving both the precision and the accuracy of Atom Probe Tomography reconstruction requires a correct understanding of the imaging process. In this aim, numerical modeling approaches have been developed for 15 years. The injected ingredients of these modeling tools are related to the basic physic of the field evaporation mechanism. The interplay between the sample nature and structure of the analyzed sample and the reconstructed image artefacts have pushed to gradually improve and make the model more and more sophisticated. This paper reviews the evolution of the modeling approach in Atom Probe Tomography and presents some future potential directions in order to improve the method. Copyright © 2015 Elsevier B.V. All rights reserved.
Analytical Model for Sensor Placement on Microprocessors
National Research Council Canada - National Science Library
Lee, Kyeong-Jae; Skadron, Kevin; Huang, Wei
2005-01-01
.... In this paper, we present an analytical model that describes the maximum temperature differential between a hot spot and a region of interest based on their distance and processor packaging information...
Analytical model of internally coupled ears
DEFF Research Database (Denmark)
Vossen, Christine; Christensen-Dalsgaard, Jakob; Leo van Hemmen, J
2010-01-01
differences in the tympanic membrane vibrations. Both cues show strong directionality. The work presented herein sets out the derivation of a three dimensional analytical model of internally coupled ears that allows for calculation of a complete vibration profile of the membranes. The analytical model...... additionally provides the opportunity to incorporate the effect of the asymmetrically attached columella, which leads to the activation of higher membrane vibration modes. Incorporating this effect, the analytical model can explain measurements taken from the tympanic membrane of a living lizard, for example......, data demonstrating an asymmetrical spatial pattern of membrane vibration. As the analytical calculations show, the internally coupled ears increase the directional response, appearing in large directional internal amplitude differences (iAD) and in large internal time differences (iTD). Numerical...
Analytical modelling of soccer heading
Indian Academy of Sciences (India)
Heading occur frequently in soccer games and studies have shown that repetitive heading of the soccer ball could result in degeneration of brain cells and lead to mild traumatic brain injury. This study proposes a two degree-of-freedom linear mathematical model to study the impact of the soccer ball on the brain. The model ...
Analytic nearest neighbour model for FCC metals
International Nuclear Information System (INIS)
Idiodi, J.O.A.; Garba, E.J.D.; Akinlade, O.
1991-06-01
A recently proposed analytic nearest-neighbour model for fcc metals is criticised and two alternative nearest-neighbour models derived from the separable potential method (SPM) are recommended. Results for copper and aluminium illustrate the utility of the recommended models. (author). 20 refs, 5 tabs
Analytical eigenstates for the quantum Rabi model
International Nuclear Information System (INIS)
Zhong, Honghua; Xie, Qiongtao; Lee, Chaohong; Batchelor, Murray T
2013-01-01
We develop a method to find analytical solutions for the eigenstates of the quantum Rabi model. These include symmetric, anti-symmetric and asymmetric analytic solutions given in terms of the confluent Heun functions. Both regular and exceptional solutions are given in a unified form. In addition, the analytic conditions for determining the energy spectrum are obtained. Our results show that conditions proposed by Braak (2011 Phys. Rev. Lett. 107 100401) are a type of sufficiency condition for determining the regular solutions. The well-known Judd isolated exact solutions appear naturally as truncations of the confluent Heun functions. (paper)
A deterministic model of electron transport for electron probe microanalysis
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.
An analytical model of flagellate hydrodynamics
DEFF Research Database (Denmark)
Dölger, Julia; Bohr, Tomas; Andersen, Anders Peter
2017-01-01
Flagellates are unicellular microswimmers that propel themselves using one or several beating flagella. We consider a hydrodynamic model of flagellates and explore the effect of flagellar arrangement and beat pattern on swimming kinematics and near-cell flow. The model is based on the analytical...
Semi-analytic modelling of subsidence
Fokker, P.A.; Orlic, B.
2006-01-01
This paper presents a forward model for subsidence prediction caused by extraction of hydrocarbons. The model uses combinations of analytic solutions to the visco-elastic equations, which approximate the boundary conditions. There are only a few unknown parameters to be estimated, and, consequently,
An analytic uranium sources model
International Nuclear Information System (INIS)
Singer, C.E.
2001-01-01
This document presents a method for estimating uranium resources as a continuous function of extraction costs and describing the uncertainty in the resulting fit. The estimated functions provide convenient extrapolations of currently available data on uranium extraction cost and can be used to predict the effect of resource depletion on future uranium supply costs. As such, they are a useful input for economic models of the nuclear energy sector. The method described here pays careful attention to minimizing built-in biases in the fitting procedure and defines ways to describe the uncertainty in the resulting fits in order to render the procedure and its results useful to the widest possible variety of potential users. (author)
Bio-analytical applications of mid-infrared spectroscopy using silver halide fiber-optic probes
International Nuclear Information System (INIS)
Heise, H.M.; Kuepper, L.; Butvina, L.N.
2002-01-01
Infrared-spectroscopy has proved to be a powerful method for the study of various biomedical samples, in particular for in-vitro analysis in the clinical laboratory and for non-invasive diagnostics. In general, the analysis of biofluids such as whole blood, urine, microdialysates and bioreactor broth media takes advantage of the fact that a multitude of analytes can be quantified simultaneously and rapidly without the need for reagents. Progress in the quality of infrared silver halide fibers enabled us to construct several flexible fiber-optic probes of different geometries, which are particularly suitable for the measurement of small biosamples. Recent trends show that dry film measurements by mid-infrared spectroscopy could revolutionize analytical tools in the clinical chemistry laboratory, and an example is given. Infrared diagnostic tools show a promising potential for patients, and minimal-invasive blood glucose assays or skin tissue pathology in particular cannot be left out using mid-infrared fiber-based probes. Other applications include the measurement of skin samples including penetration studies of vitamins and constituents of cosmetic cream formulations. A further field is the micro-domain analysis of biopsy samples from bog mummified corpses, and recent results on the chemistry of dermis and hair samples are reported. Another field of application, for which results are reported, is food analysis and bio-reactor monitoring
MASCOTTE: analytical model of eddy current signals
International Nuclear Information System (INIS)
Delsarte, G.; Levy, R.
1992-01-01
Tube examination is a major application of the eddy current technique in the nuclear and petrochemical industries. Such examination configurations being specially adapted to analytical modes, a physical model is developed on portable computers. It includes simple approximations made possible by the effective conditions of the examinations. The eddy current signal is described by an analytical formulation that takes into account the tube dimensions, the sensor conception, the physical characteristics of the defect and the examination parameters. Moreover, the model makes it possible to associate real signals and simulated signals
Modeling of the Global Water Cycle - Analytical Models
Yongqiang Liu; Roni Avissar
2005-01-01
Both numerical and analytical models of coupled atmosphere and its underlying ground components (land, ocean, ice) are useful tools for modeling the global and regional water cycle. Unlike complex three-dimensional climate models, which need very large computing resources and involve a large number of complicated interactions often difficult to interpret, analytical...
Modeling and Analytical Simulation of a Smouldering ...
African Journals Online (AJOL)
ADOWIE PERE
ABSTRACT: Modeling of pyrolysis and combustion in a smouldering fuel bed requires the solution of flow, heat and mass transfer through porous media. ..... eAt v g. RT. E gp φρ ρ σ. −. = Analytical Solution. We solve equations (10) – (14) using parameter- expanding method (where details can be found in. (He, 2006)) and ...
Analytical model for Stirling cycle machine design
Energy Technology Data Exchange (ETDEWEB)
Formosa, F. [Laboratoire SYMME, Universite de Savoie, BP 80439, 74944 Annecy le Vieux Cedex (France); Despesse, G. [Laboratoire Capteurs Actionneurs et Recuperation d' Energie, CEA-LETI-MINATEC, Grenoble (France)
2010-10-15
In order to study further the promising free piston Stirling engine architecture, there is a need of an analytical thermodynamic model which could be used in a dynamical analysis for preliminary design. To aim at more realistic values, the models have to take into account the heat losses and irreversibilities on the engine. An analytical model which encompasses the critical flaws of the regenerator and furthermore the heat exchangers effectivenesses has been developed. This model has been validated using the whole range of the experimental data available from the General Motor GPU-3 Stirling engine prototype. The effects of the technological and operating parameters on Stirling engine performance have been investigated. In addition to the regenerator influence, the effect of the cooler effectiveness is underlined. (author)
Analytical model for Stirling cycle machine design
International Nuclear Information System (INIS)
Formosa, F.; Despesse, G.
2010-01-01
In order to study further the promising free piston Stirling engine architecture, there is a need of an analytical thermodynamic model which could be used in a dynamical analysis for preliminary design. To aim at more realistic values, the models have to take into account the heat losses and irreversibilities on the engine. An analytical model which encompasses the critical flaws of the regenerator and furthermore the heat exchangers effectivenesses has been developed. This model has been validated using the whole range of the experimental data available from the General Motor GPU-3 Stirling engine prototype. The effects of the technological and operating parameters on Stirling engine performance have been investigated. In addition to the regenerator influence, the effect of the cooler effectiveness is underlined.
Automated statistical modeling of analytical measurement systems
International Nuclear Information System (INIS)
Jacobson, J.J.
1992-01-01
The statistical modeling of analytical measurement systems at the Idaho Chemical Processing Plant (ICPP) has been completely automated through computer software. The statistical modeling of analytical measurement systems is one part of a complete quality control program used by the Remote Analytical Laboratory (RAL) at the ICPP. The quality control program is an integration of automated data input, measurement system calibration, database management, and statistical process control. The quality control program and statistical modeling program meet the guidelines set forth by the American Society for Testing Materials and American National Standards Institute. A statistical model is a set of mathematical equations describing any systematic bias inherent in a measurement system and the precision of a measurement system. A statistical model is developed from data generated from the analysis of control standards. Control standards are samples which are made up at precise known levels by an independent laboratory and submitted to the RAL. The RAL analysts who process control standards do not know the values of those control standards. The object behind statistical modeling is to describe real process samples in terms of their bias and precision and, to verify that a measurement system is operating satisfactorily. The processing of control standards gives us this ability
Analytic Scattering and Refraction Models for Exoplanet Transit Spectra
Robinson, Tyler D.; Fortney, Jonathan J.; Hubbard, William B.
2017-12-01
Observations of exoplanet transit spectra are essential to understanding the physics and chemistry of distant worlds. The effects of opacity sources and many physical processes combine to set the shape of a transit spectrum. Two such key processes—refraction and cloud and/or haze forward-scattering—have seen substantial recent study. However, models of these processes are typically complex, which prevents their incorporation into observational analyses and standard transit spectrum tools. In this work, we develop analytic expressions that allow for the efficient parameterization of forward-scattering and refraction effects in transit spectra. We derive an effective slant optical depth that includes a correction for forward-scattered light, and present an analytic form of this correction. We validate our correction against a full-physics transit spectrum model that includes scattering, and we explore the extent to which the omission of forward-scattering effects may bias models. Also, we verify a common analytic expression for the location of a refractive boundary, which we express in terms of the maximum pressure probed in a transit spectrum. This expression is designed to be easily incorporated into existing tools, and we discuss how the detection of a refractive boundary could help indicate the background atmospheric composition by constraining the bulk refractivity of the atmosphere. Finally, we show that opacity from Rayleigh scattering and collision-induced absorption will outweigh the effects of refraction for Jupiter-like atmospheres whose equilibrium temperatures are above 400-500 K.
Comparison of analytical eddy current models using principal components analysis
Contant, S.; Luloff, M.; Morelli, J.; Krause, T. W.
2017-02-01
Monitoring the gap between the pressure tube (PT) and the calandria tube (CT) in CANDU® fuel channels is essential, as contact between the two tubes can lead to delayed hydride cracking of the pressure tube. Multifrequency transmit-receive eddy current non-destructive evaluation is used to determine this gap, as this method has different depths of penetration and variable sensitivity to noise, unlike single frequency eddy current non-destructive evaluation. An Analytical model based on the Dodd and Deeds solutions, and a second model that accounts for normal and lossy self-inductances, and a non-coaxial pickup coil, are examined for representing the response of an eddy current transmit-receive probe when considering factors that affect the gap response, such as pressure tube wall thickness and pressure tube resistivity. The multifrequency model data was analyzed using principal components analysis (PCA), a statistical method used to reduce the data set into a data set of fewer variables. The results of the PCA of the analytical models were then compared to PCA performed on a previously obtained experimental data set. The models gave similar results under variable PT wall thickness conditions, but the non-coaxial coil model, which accounts for self-inductive losses, performed significantly better than the Dodd and Deeds model under variable resistivity conditions.
Prediction of ultrasonic probe characteristics through modeling and simulation
International Nuclear Information System (INIS)
Amry Amin Abas; Mohamad Pauzi Ismail; Suhairy Sani
2004-01-01
One of the main component in an ultrasonic probe is piezoelectric material. It converts electrical energy supplied to it into mechanical energy (i.e. sound waves) and vice versa. In industrial application, the characteristic of ultrasonic probes is important as it will affect the results obtained. The probes fabricated must possess the characteristics suitable to the intended application. Through modeling and simulation, we can predict the characteristics of the probes. Mason equivalent circuit is used to make a model and simulation of the probes. In this model, the probes will be treated and simplified as a one dimensional electrical line. From simulation, the electrical properties such as impedance, operating frequency bandwidth and others can be predicted. From this model, the correct material to be used for actual probe construction can be obtained. The limitation of this method is details such as bond line between layers is not taken into consideration. (Author)
MATLAB/Simulink analytic radar modeling environment
Esken, Bruce L.; Clayton, Brian L.
2001-09-01
Analytic radar models are simulations based on abstract representations of the radar, the RF environment that radar signals are propagated, and the reflections produced by targets, clutter and multipath. These models have traditionally been developed in FORTRAN and have evolved over the last 20 years into efficient and well-accepted codes. However, current models are limited in two primary areas. First, by the nature of algorithm based analytical models, they can be difficult to understand by non-programmers and equally difficult to modify or extend. Second, there is strong interest in re-using these models to support higher-level weapon system and mission level simulations. To address these issues, a model development approach has been demonstrated which utilizes the MATLAB/Simulink graphical development environment. Because the MATLAB/Simulink environment graphically represents model algorithms - thus providing visibility into the model - algorithms can be easily analyzed and modified by engineers and analysts with limited software skills. In addition, software tools have been created that provide for the automatic code generation of C++ objects. These objects are created with well-defined interfaces enabling them to be used by modeling architectures external to the MATLAB/Simulink environment. The approach utilized is generic and can be extended to other engineering fields.
SIMMER-III analytic thermophysical property model
International Nuclear Information System (INIS)
Morita, K; Tobita, Y.; Kondo, Sa.; Fischer, E.A.
1999-05-01
An analytic thermophysical property model using general function forms is developed for a reactor safety analysis code, SIMMER-III. The function forms are designed to represent correct behavior of properties of reactor-core materials over wide temperature ranges, especially for the thermal conductivity and the viscosity near the critical point. The most up-to-date and reliable sources for uranium dioxide, mixed-oxide fuel, stainless steel, and sodium available at present are used to determine parameters in the proposed functions. This model is also designed to be consistent with a SIMMER-III model on thermodynamic properties and equations of state for reactor-core materials. (author)
Organizational Models for Big Data and Analytics
Directory of Open Access Journals (Sweden)
Robert L. Grossman
2014-04-01
Full Text Available In this article, we introduce a framework for determining how analytics capability should be distributed within an organization. Our framework stresses the importance of building a critical mass of analytics staff, centralizing or decentralizing the analytics staff to support business processes, and establishing an analytics governance structure to ensure that analytics processes are supported by the organization as a whole.
Analytical modeling of parametrically modulated transmon qubits
Didier, Nicolas; Sete, Eyob A.; da Silva, Marcus P.; Rigetti, Chad
2018-02-01
Building a scalable quantum computer requires developing appropriate models to understand and verify its complex quantum dynamics. We focus on superconducting quantum processors based on transmons for which full numerical simulations are already challenging at the level of qubytes. It is thus highly desirable to develop accurate methods of modeling qubit networks that do not rely solely on numerical computations. Using systematic perturbation theory to large orders in the transmon regime, we derive precise analytic expressions of the transmon parameters. We apply our results to the case of parametrically modulated transmons to study recently implemented, parametrically activated entangling gates.
An analytical model for interactive failures
International Nuclear Information System (INIS)
Sun Yong; Ma Lin; Mathew, Joseph; Zhang Sheng
2006-01-01
In some systems, failures of certain components can interact with each other, and accelerate the failure rates of these components. These failures are defined as interactive failure. Interactive failure is a prevalent cause of failure associated with complex systems, particularly in mechanical systems. The failure risk of an asset will be underestimated if the interactive effect is ignored. When failure risk is assessed, interactive failures of an asset need to be considered. However, the literature is silent on previous research work in this field. This paper introduces the concepts of interactive failure, develops an analytical model to analyse this type of failure quantitatively, and verifies the model using case studies and experiments
Analytical model of the optical vortex microscope.
Płocinniczak, Łukasz; Popiołek-Masajada, Agnieszka; Masajada, Jan; Szatkowski, Mateusz
2016-04-20
This paper presents an analytical model of the optical vortex scanning microscope. In this microscope the Gaussian beam with an embedded optical vortex is focused into the sample plane. Additionally, the optical vortex can be moved inside the beam, which allows fine scanning of the sample. We provide an analytical solution of the whole path of the beam in the system (within paraxial approximation)-from the vortex lens to the observation plane situated on the CCD camera. The calculations are performed step by step from one optical element to the next. We show that at each step, the expression for light complex amplitude has the same form with only four coefficients modified. We also derive a simple expression for the vortex trajectory of small vortex displacements.
Building analytical three-field cosmological models
Santos, J. R. L.; Moraes, P. H. R. S.; Ferreira, D. A.; Neta, D. C. Vilar
2018-02-01
A difficult task to deal with is the analytical treatment of models composed of three real scalar fields, as their equations of motion are in general coupled and hard to integrate. In order to overcome this problem we introduce a methodology to construct three-field models based on the so-called "extension method". The fundamental idea of the procedure is to combine three one-field systems in a non-trivial way, to construct an effective three scalar field model. An interesting scenario where the method can be implemented is with inflationary models, where the Einstein-Hilbert Lagrangian is coupled with the scalar field Lagrangian. We exemplify how a new model constructed from our method can lead to non-trivial behaviors for cosmological parameters.
Analytic models of plausible gravitational lens potentials
International Nuclear Information System (INIS)
Baltz, Edward A.; Marshall, Phil; Oguri, Masamune
2009-01-01
Gravitational lenses on galaxy scales are plausibly modelled as having ellipsoidal symmetry and a universal dark matter density profile, with a Sérsic profile to describe the distribution of baryonic matter. Predicting all lensing effects requires knowledge of the total lens potential: in this work we give analytic forms for that of the above hybrid model. Emphasising that complex lens potentials can be constructed from simpler components in linear combination, we provide a recipe for attaining elliptical symmetry in either projected mass or lens potential. We also provide analytic formulae for the lens potentials of Sérsic profiles for integer and half-integer index. We then present formulae describing the gravitational lensing effects due to smoothly-truncated universal density profiles in cold dark matter model. For our isolated haloes the density profile falls off as radius to the minus fifth or seventh power beyond the tidal radius, functional forms that allow all orders of lens potential derivatives to be calculated analytically, while ensuring a non-divergent total mass. We show how the observables predicted by this profile differ from that of the original infinite-mass NFW profile. Expressions for the gravitational flexion are highlighted. We show how decreasing the tidal radius allows stripped haloes to be modelled, providing a framework for a fuller investigation of dark matter substructure in galaxies and clusters. Finally we remark on the need for finite mass halo profiles when doing cosmological ray-tracing simulations, and the need for readily-calculable higher order derivatives of the lens potential when studying catastrophes in strong lenses
An analytical model for climatic predictions
International Nuclear Information System (INIS)
Njau, E.C.
1990-12-01
A climatic model based upon analytical expressions is presented. This model is capable of making long-range predictions of heat energy variations on regional or global scales. These variations can then be transformed into corresponding variations of some other key climatic parameters since weather and climatic changes are basically driven by differential heating and cooling around the earth. On the basis of the mathematical expressions upon which the model is based, it is shown that the global heat energy structure (and hence the associated climatic system) are characterized by zonally as well as latitudinally propagating fluctuations at frequencies downward of 0.5 day -1 . We have calculated the propagation speeds for those particular frequencies that are well documented in the literature. The calculated speeds are in excellent agreement with the measured speeds. (author). 13 refs
Approximate analytical modeling of leptospirosis infection
Ismail, Nur Atikah; Azmi, Amirah; Yusof, Fauzi Mohamed; Ismail, Ahmad Izani
2017-11-01
Leptospirosis is an infectious disease carried by rodents which can cause death in humans. The disease spreads directly through contact with feces, urine or through bites of infected rodents and indirectly via water contaminated with urine and droppings from them. Significant increase in the number of leptospirosis cases in Malaysia caused by the recent severe floods were recorded during heavy rainfall season. Therefore, to understand the dynamics of leptospirosis infection, a mathematical model based on fractional differential equations have been developed and analyzed. In this paper an approximate analytical method, the multi-step Laplace Adomian decomposition method, has been used to conduct numerical simulations so as to gain insight on the spread of leptospirosis infection.
Simple Analytic Models of Gravitational Collapse
Energy Technology Data Exchange (ETDEWEB)
Adler, R.
2005-02-09
Most general relativity textbooks devote considerable space to the simplest example of a black hole containing a singularity, the Schwarzschild geometry. However only a few discuss the dynamical process of gravitational collapse, by which black holes and singularities form. We present here two types of analytic models for this process, which we believe are the simplest available; the first involves collapsing spherical shells of light, analyzed mainly in Eddington-Finkelstein coordinates; the second involves collapsing spheres filled with a perfect fluid, analyzed mainly in Painleve-Gullstrand coordinates. Our main goal is pedagogical simplicity and algebraic completeness, but we also present some results that we believe are new, such as the collapse of a light shell in Kruskal-Szekeres coordinates.
Graph and Analytical Models for Emergency Evacuation
Directory of Open Access Journals (Sweden)
Erol Gelenbe
2013-02-01
Full Text Available Cyber-Physical-Human Systems (CPHS combine sensing, communication and control to obtain desirable outcomes in physical environments for human beings, such as buildings or vehicles. A particularly important application area is emergency management. While recent work on the design and optimisation of emergency management schemes has relied essentially on discrete event simulation, which is challenged by the substantial amount of programming or reprogramming of the simulation tools and by the scalability and the computing time needed to obtain useful performance estimates, this paper proposes an approach that offers fast estimates based on graph models and probability models. We show that graph models can offer insight into the critical areas in an emergency evacuation and that they can suggest locations where sensor systems are particularly important and may require hardening. On the other hand, we also show that analytical models based on queueing theory can provide useful estimates of evacuation times and for routing optimisation. The results are illustrated with regard to the evacuation of a real-life building.
An analytical model of flagellate hydrodynamics
International Nuclear Information System (INIS)
Dölger, Julia; Bohr, Tomas; Andersen, Anders
2017-01-01
Flagellates are unicellular microswimmers that propel themselves using one or several beating flagella. We consider a hydrodynamic model of flagellates and explore the effect of flagellar arrangement and beat pattern on swimming kinematics and near-cell flow. The model is based on the analytical solution by Oseen for the low Reynolds number flow due to a point force outside a no-slip sphere. The no-slip sphere represents the cell and the point force a single flagellum. By superposition we are able to model a freely swimming flagellate with several flagella. For biflagellates with left–right symmetric flagellar arrangements we determine the swimming velocity, and we show that transversal forces due to the periodic movements of the flagella can promote swimming. For a model flagellate with both a longitudinal and a transversal flagellum we determine radius and pitch of the helical swimming trajectory. We find that the longitudinal flagellum is responsible for the average translational motion whereas the transversal flagellum governs the rotational motion. Finally, we show that the transversal flagellum can lead to strong feeding currents to localized capture sites on the cell surface. (paper)
Modeling the effect of probe force on length measurements on polymer parts
DEFF Research Database (Denmark)
Mohammadi, Ali; Sonne, Mads Rostgaard; Dalla Costa, Giuseppe
2016-01-01
Measurement uncertainty at micrometer level is in the future going to be very common in dimensional measurements on polymer parts. Accurate dimensional measurement of polymer parts is becoming a key and common practice in the industry, especially when micrometer tolerances are required. When...... numerically. Both analytical and numerical approaches were compared with the experimental results. The results showed that the numerical model was able to predict the deformation of the polymer part due to different probe forces. Furthermore it was shown, that the probe force should be taking into account...... when measurement with a few micrometer accuracy should be performed on thin walled polymer parts....
Level set methods for modelling field evaporation in atom probe.
Haley, Daniel; Moody, Michael P; Smith, George D W
2013-12-01
Atom probe is a nanoscale technique for creating three-dimensional spatially and chemically resolved point datasets, primarily of metallic or semiconductor materials. While atom probe can achieve local high-level resolution, the spatial coherence of the technique is highly dependent upon the evaporative physics in the material and can often result in large geometric distortions in experimental results. The distortions originate from uncertainties in the projection function between the field evaporating specimen and the ion detector. Here we explore the possibility of continuum numerical approximations to the evaporative behavior during an atom probe experiment, and the subsequent propagation of ions to the detector, with particular emphasis placed on the solution of axisymmetric systems, such as isolated particles and multilayer systems. Ultimately, this method may prove critical in rapid modeling of tip shape evolution in atom probe tomography, which itself is a key factor in the rapid generation of spatially accurate reconstructions in atom probe datasets.
Analytic modeling of axisymmetric disruption halo currents
International Nuclear Information System (INIS)
Humphreys, D.A.; Kellman, A.G.
1999-01-01
Currents which can flow in plasma facing components during disruptions pose a challenge to the design of next generation tokamaks. Induced toroidal eddy currents and both induced and conducted poloidal ''halo'' currents can produce design-limiting electromagnetic loads. While induction of toroidal and poloidal currents in passive structures is a well-understood phenomenon, the driving terms and scalings for poloidal currents flowing on open field lines during disruptions are less well established. A model of halo current evolution is presented in which the current is induced in the halo by decay of the plasma current and change in enclosed toroidal flux while being convected into the halo from the core by plasma motion. Fundamental physical processes and scalings are described in a simplified analytic version of the model. The peak axisymmetric halo current is found to depend on halo and core plasma characteristics during the current quench, including machine and plasma dimensions, resistivities, safety factor, and vertical stability growth rate. Two extreme regimes in poloidal halo current amplitude are identified depending on the minimum halo safety factor reached during the disruption. A 'type I' disruption is characterized by a minimum safety factor that remains relatively high (typically 2 - 3, comparable to the predisruption safety factor), and a relatively low poloidal halo current. A 'type II' disruption is characterized by a minimum safety factor comparable to unity and a relatively high poloidal halo current. Model predictions for these two regimes are found to agree well with halo current measurements from vertical displacement event disruptions in DIII-D [T. S. Taylor, K. H. Burrell, D. R. Baker, G. L. Jackson, R. J. La Haye, M. A. Mahdavi, R. Prater, T. C. Simonen, and A. D. Turnbull, open-quotes Results from the DIII-D Scientific Research Program,close quotes in Proceedings of the 17th IAEA Fusion Energy Conference, Yokohama, 1998, to be published in
Analytical model of tilted driver–pickup coils for eddy current nondestructive evaluation
Cao, Bing-Hua; Li, Chao; Fan, Meng-Bao; Ye, Bo; Tian, Gui-Yun
2018-03-01
A driver-pickup probe possesses better sensitivity and flexibility due to individual optimization of a coil. It is frequently observed in an eddy current (EC) array probe. In this work, a tilted non-coaxial driver-pickup probe above a multilayered conducting plate is analytically modeled with spatial transformation for eddy current nondestructive evaluation. Basically, the core of the formulation is to obtain the projection of magnetic vector potential (MVP) from the driver coil onto the vector along the tilted pickup coil, which is divided into two key steps. The first step is to make a projection of MVP along the pickup coil onto a horizontal plane, and the second one is to build the relationship between the projected MVP and the MVP along the driver coil. Afterwards, an analytical model for the case of a layered plate is established with the reflection and transmission theory of electromagnetic fields. The calculated values from the resulting model indicate good agreement with those from the finite element model (FEM) and experiments, which validates the developed analytical model. Project supported by the National Natural Science Foundation of China (Grant Nos. 61701500, 51677187, and 51465024).
The US Army HazMin probe model
International Nuclear Information System (INIS)
Kuusinen, T.; Dirks, J.; Brothers, A.; Fowler, K.; Skumanich, M.; Scola, R.; Perich, A.; Napolitano, M.
1993-03-01
In 1987, the US Department of Defense (DOD) established a goal of reducing the quantity of hazardous waste generated by DOD facilities by 50%. To help achieve this goal, the US Army Production Base Modernization Activity (PBMA) has contracted with the Pacific Northwest Laboratory (PNL) to develop decision support software to be used in the Army-wide hazardous waste minimization (HazMin) program. The resulting waste minimization prioritization software has been named the Project Opportunity and Benefit Evaluation (PROBE) model. PROBE can be used to evaluate both waste stream and project priorities. PROBE operates on any IBM-compatible personal computer hardware with at least 640K of memory and 5 megabytes of available hard disk space. PROBE was developed under the direction of PBMA, which retains unlimited rights to the Federal version of PROBE. PBMA encourages other DOD services and other Federal agencies to use PROBE to assist in their own waste minimization programs. PNL is also considering developing a copyrighted version of PROBE for the commercial market. PROBE was written using FoxPro 2.0 application development software, and runs as an executable file from either MS-DOS or Windows. The software can be loaded onto a single high-capacity floppy disk in a compressed format and can be transferred onto hard disk, ready to operate, via a simple start-up routine
Modeling and analytical simulation of a smouldering carbonaceous ...
African Journals Online (AJOL)
Modeling and analytical simulation of a smouldering carbonaceous rod. A.A. Mohammed, R.O. Olayiwola, M Eseyin, A.A. Wachin. Abstract. Modeling of pyrolysis and combustion in a smouldering fuel bed requires the solution of flow, heat and mass transfer through porous media. This paper presents an analytical method ...
Numerical Modelling of Eddy Current Probes for CANDU RTM Fuel Channel Inspection
Luloff, Mark Stephen
Multi-frequency Eddy Current (EC) inspection with a transmit-receive probe (two horizontally offset coils) is used to monitor the Pressure Tube (PT) to Calandria Tube (CT) gap of CANDU fuel channels. Accurate gap measurements are crucial to ensure fitness of service; however, variations in probe liftoff, PT electrical resistivity, and PT wall thickness can generate systematic measurement errors. Validated mathematical models of the EC probe are very useful for data interpretation, and may improve the gap measurement under inspection conditions where these parameters vary. As a first step, exact solutions for the electromagnetic response of a transmit-receive coil pair situated above two parallel plates separated by an air gap were developed. This model was validated against experimental data with flat-plate samples. Finite element method models revealed that this geometrical approximation could not accurately match experimental data with real tubes, so analytical solutions for the probe in a double-walled pipe (the CANDU fuel channel geometry) were generated using the Second-Order Vector Potential (SOVP) formalism. All electromagnetic coupling coefficients arising from the probe, and the layered conductors were determined and substituted into Kirchhoff's circuit equations for the calculation of the pickup coil signal. The flat-plate model was used as a basis for an Inverse Algorithm (IA) to simultaneously extract the relevant experimental parameters from EC data. The IA was validated over a large range of second layer plate resistivities (1.7 to 174 plate, microO·cm) wall thickness ( 1 to 4.9 mm), probe liftoff ( 2 mm to 8 mm), and plate-to plate gap ( 0 mm to 13 mm). The IA achieved a relative error of less than 6% for the extracted FP resistivity and an accuracy of +/-0.1 mm for the LO measurement. The IA was able to achieve a plate gap measurement with an accuracy of less than +/-0.7 mm error over a 2.4 mm to 7.5 mm probe liftoff and +/-0.3 mm at nominal
Analytically solvable models of reaction-diffusion systems
Energy Technology Data Exchange (ETDEWEB)
Zemskov, E P; Kassner, K [Institut fuer Theoretische Physik, Otto-von-Guericke-Universitaet, Universitaetsplatz 2, 39106 Magdeburg (Germany)
2004-05-01
We consider a class of analytically solvable models of reaction-diffusion systems. An analytical treatment is possible because the nonlinear reaction term is approximated by a piecewise linear function. As particular examples we choose front and pulse solutions to illustrate the matching procedure in the one-dimensional case.
Probing NWP model deficiencies by statistical postprocessing
DEFF Research Database (Denmark)
Rosgaard, Martin Haubjerg; Nielsen, Henrik Aalborg; Nielsen, Torben S.
2016-01-01
The objective in this article is twofold. On one hand, a Model Output Statistics (MOS) framework for improved wind speed forecast accuracy is described and evaluated. On the other hand, the approach explored identifies unintuitive explanatory value from a diagnostic variable in an operational num...
Analytical modeling of masonry infilled steel frames
International Nuclear Information System (INIS)
Flanagan, R.D.; Jones, W.D.; Bennett, R.M.
1991-01-01
A comprehensive program is underway at the Oak Ridge Y-12 Plant to evaluate the seismic capacity of unreinforced hollow clay tile infilled steel frames. This program has three major parts. First, preliminary numerical analyses are conducted to predict behavior, initial cracking loads, ultimate capacity loads, and to identify important parameters. Second, in-situ and laboratory tests are performed to obtain constitutive parameters and confirm predicted behavior. Finally, the analytical techniques are refined based on experimental results. This paper summarizes the findings of the preliminary numerical analyses. A review of current analytical methods was conducted and a subset of these methods was applied to known experimental results. Parametric studies were used to find the sensitivity of the behavior to various parameters. Both in-plane and out-of-plane loads were examined. Two types of out-of-plane behavior were examined, the inertial forces resulting from the mass of the infill panel and the out-of-plane forces resulting from interstory drift. Cracking loads were estimated using linear elastic analysis and an elliptical failure criterion. Calculated natural frequencies were correlated with low amplitude vibration testing. Ultimate behavior under inertial loads was estimated using a modified yield line procedure accounting for membrane stresses. The initial stiffness and ultimate capacity under in-plane loadings were predicted using finite element analyses. Results were compared to experimental data and to failure loads obtained using plastic collapse theory
International Nuclear Information System (INIS)
Wong, K. M.; Chim, W. K.
2007-01-01
An approach for fast and accurate carrier profiling using deep-depletion analytical modeling of scanning capacitance microscopy (SCM) measurements is shown for an ultrashallow p-n junction with a junction depth of less than 30 nm and a profile steepness of about 3 nm per decade change in carrier concentration. In addition, the analytical model is also used to extract the SCM dopant profiles of three other p-n junction samples with different junction depths and profile steepnesses. The deep-depletion effect arises from rapid changes in the bias applied between the sample and probe tip during SCM measurements. The extracted carrier profile from the model agrees reasonably well with the more accurate carrier profile from inverse modeling and the dopant profile from secondary ion mass spectroscopy measurements
Feedbacks Between Numerical and Analytical Models in Hydrogeology
Zlotnik, V. A.; Cardenas, M. B.; Toundykov, D.; Cohn, S.
2012-12-01
Hydrogeology is a relatively young discipline which combines elements of Earth science and engineering. Mature fundamental disciplines (e.g., physics, chemistry, fluid mechanics) have centuries-long history of mathematical modeling even prior to discovery of Darcy's law. Thus, in hydrogeology, relatively few classic analytical models (such those by Theis, Polubarinova-Kochina, Philip, Toth, Henry, Dagan, Neuman) were developed by the early 1970's. The advent of computers and practical demands refocused mathematical models towards numerical techniques. With more diverse but less mathematically-oriented training, most hydrogeologists shifted from analytical methods to use of standardized computational software. Spatial variability in internal properties and external boundary conditions and geometry, and the added complexity of chemical and biological processes will remain major challenges for analytical modeling. Possibly, analytical techniques will play a subordinate role to numerical approaches in many applications. On the other hand, the rise of analytical element modeling of groundwater flow is a strong alternative to numerical models when data demand and computational efficiency is considered. The hallmark of analytical models - transparency and accuracy - will remain indispensable for scientific exploration of complex phenomena and for benchmarking numerical models. Therefore, there will always be feedbacks and complementarities between numerical and analytical techniques, as well as a certain ideological schism among various views to modeling. We illustrate the idea of feedbacks by reviewing evolution of Joszef Toth's analytical model of gravity driven flow systems. Toth's (1963) approach was to reduce the flow domain to a rectangle which allowed for closed-form solution of the governing equations. Succeeding numerical finite-element models by Freeze and Witherspoon (1966-1968) explored the effects of geometry and heterogeneity on regional groundwater flow
Gomila, G; Gramse, G; Fumagalli, L
2014-06-27
A numerical analysis of the polarization force between a sharp conducting probe and a dielectric film of finite lateral dimensions on a metallic substrate is presented with the double objective of (i) determining the conditions under which the film can be approximated by a laterally infinite film and (ii) proposing an analytical model valid in this limit. We show that, for a given dielectric film, the critical diameter above which the film can be modeled as laterally infinite depends not only on the probe geometry, as expected, but mainly on the film thickness. In particular, for films with intermediate to large thicknesses (>100 nm), the critical diameter is nearly independent from the probe geometry and essentially depends on the film thickness and dielectric constant following a relatively simple phenomenological expression. For films that can be considered as laterally infinite, we propose a generalized analytical model valid in the thin-ultrathin limit (<20-50 nm) that reproduces the numerical calculations and the experimental data. Present results provide a general framework under which accurate quantification of electrostatic force microscopy measurements on dielectric films on metallic substrates can be achieved.
Analytic Models for Sunlight Charging of a Rapidly Spinning Satellite
National Research Council Canada - National Science Library
Tautz, Maurice
2003-01-01
... photoelectrons can be blocked by local potential barriers. In this report, we discuss two analytic models for sunlight charging of a rapidly spinning spherical satellite, both of which are based on blocked photoelectron currents...
Analytical Models Development of Compact Monopole Vortex Flows
Directory of Open Access Journals (Sweden)
Pavlo V. Lukianov
2017-09-01
Conclusions. The article contains series of the latest analytical models that describe both laminar and turbulent dynamics of monopole vortex flows which have not been reflected in traditional publications up to the present. The further research must be directed to search of analytical models for the coherent vortical structures in flows of viscous fluids, particularly near curved surfaces, where known in hydromechanics “wall law” is disturbed and heat and mass transfer anomalies take place.
International Nuclear Information System (INIS)
Fujita, Takaya; Matsumura, Koji; Itoh, Hiroshi; Fujita, Daisuke
2014-01-01
Scanning capacitance microscopy (SCM) is based on a contact-mode variant of atomic force microscopy, which is used for imaging two-dimensional carrier (electrons and holes) distributions in semiconductor devices. We introduced a method of quantification of the carrier concentration by experimentally deduced calibration curves, which were prepared for semiconductor materials such as silicon and silicon carbide. The analytical procedure was circulated to research organizations in a round-robin test. The effectiveness of the method was confirmed for practical analysis and for what is expected for industrial pre-standardization from the viewpoint of comparability among users. It was also applied to other electric scanning probe microscopy techniques such as scanning spreading resistance microscopy and scanning nonlinear dielectric microscopy. Their depth profiles of carrier concentration were found to be in good agreement with those characterized by SCM. These results suggest that our proposed method will be compatible with future next-generation microscopy. (paper)
Analytical Model for Fictitious Crack Propagation in Concrete Beams
DEFF Research Database (Denmark)
Ulfkjær, J. P.; Krenk, S.; Brincker, Rune
An analytical model for load-displacement curves of unreinforced notched and un-notched concrete beams is presented. The load displacement-curve is obtained by combining two simple models. The fracture is modelled by a fictitious crack in an elastic layer around the mid-section of the beam. Outside...... the elastic layer the deformations are modelled by the Timoshenko beam theory. The state of stress in the elastic layer is assumed to depend bi-lineary on local elongation corresponding to a linear softening relation for the fictitious crack. For different beam size results from the analytical model...... is compared with results from a more accurate model based on numerical methods. The analytical model is shown to be in good agreement with the numerical results if the thickness of the elastic layer is taken as half the beam depth. Several general results are obtained. It is shown that the point on the load...
Analytical Model for Fictitious Crack Propagation in Concrete Beams
DEFF Research Database (Denmark)
Ulfkjær, J. P.; Krenk, Steen; Brincker, Rune
1995-01-01
An analytical model for load-displacement curves of concrete beams is presented. The load-displacement curve is obtained by combining two simple models. The fracture is modeled by a fictitious crack in an elastic layer around the midsection of the beam. Outside the elastic layer the deformations...... are modeled by beam theory. The state of stress in the elastic layer is assumed to depend bilinearly on local elongation corresponding to a linear softening relation for the fictitious crack. Results from the analytical model are compared with results from a more detailed model based on numerical methods...... for different beam sizes. The analytical model is shown to be in agreement with the numerical results if the thickness of the elastic layer is taken as half the beam depth. It is shown that the point on the load-displacement curve where the fictitious crack starts to develop and the point where the real crack...
Optical measurements and analytical modeling of magnetic field generated in a dieletric target
Yafeng, BAI; Shiyi, ZHOU; Yushan, ZENG; Yihan, LIANG; Rong, QI; Wentao, LI; Ye, TIAN; Xiaoya, LI; Jiansheng, LIU
2018-01-01
Polarization rotation of a probe pulse by the target is observed with the Faraday rotation method in the interaction of an intense laser pulse with a solid target. The rotation of the polarization plane of the probe pulse may result from a combined action of fused silica and diffused electrons. After the irradiation of the main pulse, the rotation angle changed significantly and lasted ∼2 ps. These phenomena may imply a persistent magnetic field inside the target. An analytical model is developed to explain the experimental observation. The model indicates that a strong toroidal magnetic field is induced by an energetic electron beam. Meanwhile, an ionization channel is observed in the shadowgraph and extends at the speed of light after the irradiation of the main beam. The formation of this ionization channel is complex, and a simple explanation is given.
Analytical system dynamics modeling and simulation
Fabien, Brian C
2008-01-01
This book offering a modeling technique based on Lagrange's energy method includes 125 worked examples. Using this technique enables one to model and simulate systems as diverse as a six-link, closed-loop mechanism or a transistor power amplifier.
Analytical modeling of nonradial expansion plumes
Boyd, Iain D.
1990-01-01
The 'Modified Simons' model presented allows the nonradial nature of axisymmetric rocket and thruster plume flowfields having a large exit Mach number and/or a large nozzle exit half-angle to be successfully predicted. The model is applied to monatomic and polyatomic gas (N, Ar, tetrafluoromethane) expansions; the nonradial density decay observed experimentally is successfully predicted.
Role of nuclear analytical probe techniques in biological trace element research
International Nuclear Information System (INIS)
Jones, K.W.; Pounds, J.G.
1985-01-01
Many biomedical experiments require the qualitative and quantitative localization of trace elements with high sensitivity and good spatial resolution. The feasibility of measuring the chemical form of the elements, the time course of trace elements metabolism, and of conducting experiments in living biological systems are also important requirements for biological trace element research. Nuclear analytical techniques that employ ion or photon beams have grown in importance in the past decade and have led to several new experimental approaches. Some of the important features of these methods are reviewed here along with their role in trace element research, and examples of their use are given to illustrate potential for new research directions. It is emphasized that the effective application of these methods necessitates a closely integrated multidisciplinary scientific team. 21 refs., 4 figs., 1 tab
Analytical Model for Hook Anchor Pull-Out
DEFF Research Database (Denmark)
Brincker, Rune; Ulfkjær, Jens Peder; Adamsen, Peter
1995-01-01
A simple analytical model for the pull-out of a hook anchor is presented. The model is based on a simplified version of the fictitious crack model. It is assumed that the fracture process is the pull-off of a cone shaped concrete part, simplifying the problem by assuming pure rigid body motions...
Analytical Model for Hook Anchor Pull-out
DEFF Research Database (Denmark)
Brincker, Rune; Ulfkjær, J. P.; Adamsen, P.
A simple analytical model for the pull-out of a hook anchor is presented. The model is based on a simplified version of the fictitious crack model. It is assumed that the fracture process is the pull-off of a cone shaped concrete part, simplifying the problem by assuming pure rigid body motions...
Adur, Rohan; Du, Chunhui; Manuilov, Sergei A.; Wang, Hailong; Yang, Fengyuan; Pelekhov, Denis V.; Hammel, P. Chris
2015-05-01
The dipole field from a probe magnet can be used to localize a discrete spectrum of standing spin wave modes in a continuous ferromagnetic thin film without lithographic modification to the film. Obtaining the resonance field for a localized mode is not trivial due to the effect of the confined and inhomogeneous magnetization precession. We compare the results of micromagnetic and analytic methods to find the resonance field of localized modes in a ferromagnetic thin film, and investigate the accuracy of these methods by comparing with a numerical minimization technique that assumes Bessel function modes with pinned boundary conditions. We find that the micromagnetic technique, while computationally more intensive, reveals that the true magnetization profiles of localized modes are similar to Bessel functions with gradually decaying dynamic magnetization at the mode edges. We also find that an analytic solution, which is simple to implement and computationally much faster than other methods, accurately describes the resonance field of localized modes when exchange fields are negligible, and demonstrating the accessibility of localized mode analysis.
Finite analytic method for modeling variably saturated flows.
Zhang, Zaiyong; Wang, Wenke; Gong, Chengcheng; Yeh, Tian-Chyi Jim; Wang, Zhoufeng; Wang, Yu-Li; Chen, Li
2018-04-15
This paper develops a finite analytic method (FAM) for solving the two-dimensional Richards' equation. The FAM incorporates the analytic solution in local elements to formulate the algebraic representation of the partial differential equation of unsaturated flow so as to effectively control both numerical oscillation and dispersion. The FAM model is then verified using four examples, in which the numerical solutions are compared with analytical solutions, solutions from VSAFT2, and observational data from a field experiment. These numerical experiments show that the method is not only accurate but also efficient, when compared with other numerical methods. Copyright © 2017 Elsevier B.V. All rights reserved.
Analytical model of impedance in elliptical beam pipes
Pesah, Arthur Chalom
2017-01-01
Beam instabilities are among the main limitations in building higher intensity accelerators. Having a good impedance model for every accelerators is necessary in order to build components that minimize the probability of instabilities caused by the interaction beam-environment and to understand what piece to change in case of intensity increasing. Most of accelerator components have their impedance simulated with finite elements method (using softwares like CST Studio), but simple components such as circular or flat pipes are modeled analytically, with a decreasing computation time and an increasing precision compared to their simulated model. Elliptical beam pipes, while being a simple component present in some accelerators, still misses a good analytical model working for the hole range of velocities and frequencies. In this report, we present a general framework to study the impedance of elliptical pipes analytically. We developed a model for both longitudinal and transverse impedance, first in the case of...
Analytical study of anisotropic compact star models
Ivanov, B. V.
2017-11-01
A simple classification is given of the anisotropic relativistic star models, resembling the one of charged isotropic solutions. On the ground of this database, and taking into account the conditions for physically realistic star models, a method is proposed for generating all such solutions. It is based on the energy density and the radial pressure as seeding functions. Numerous relations between the realistic conditions are found and the need for a graphic proof is reduced just to one pair of inequalities. This general formalism is illustrated with an example of a class of solutions with linear equation of state and simple energy density. It is found that the solutions depend on three free constants and concrete examples are given. Some other popular models are studied with the same method.
Analytical study of anisotropic compact star models
Energy Technology Data Exchange (ETDEWEB)
Ivanov, B.V. [Bulgarian Academy of Science, Institute for Nuclear Research and Nuclear Energy, Sofia (Bulgaria)
2017-11-15
A simple classification is given of the anisotropic relativistic star models, resembling the one of charged isotropic solutions. On the ground of this database, and taking into account the conditions for physically realistic star models, a method is proposed for generating all such solutions. It is based on the energy density and the radial pressure as seeding functions. Numerous relations between the realistic conditions are found and the need for a graphic proof is reduced just to one pair of inequalities. This general formalism is illustrated with an example of a class of solutions with linear equation of state and simple energy density. It is found that the solutions depend on three free constants and concrete examples are given. Some other popular models are studied with the same method. (orig.)
Meta-analytic structural equation modelling
Jak, Suzanne
2015-01-01
This book explains how to employ MASEM, the combination of meta-analysis (MA) and structural equation modelling (SEM). It shows how by using MASEM, a single model can be tested to explain the relationships between a set of variables in several studies. This book gives an introduction to MASEM, with a focus on the state of the art approach: the two stage approach of Cheung and Cheung & Chan. Both, the fixed and the random approach to MASEM are illustrated with two applications to real data. All steps that have to be taken to perform the analyses are discussed extensively. All data and syntax files are available online, so that readers can imitate all analyses. By using SEM for meta-analysis, this book shows how to benefit from all available information from all available studies, even if few or none of the studies report about all relationships that feature in the full model of interest.
Analytical modeling of inverted annular film boiling
International Nuclear Information System (INIS)
Analytis, G.T.; Yadigaroglu, G.
1987-01-01
By employing a two-fluid formulation similar to the one used in the most recent LWR accident analysis codes, a model for the Inverted Annular Film Boiling region is developed. The conservation equations, together with appropriate closure relations are solved numerically. Successful comparisons are made between model predictions and heat transfer coefficient distributions measured in a series of single-tube reflooding experiments. Generally, the model predicts correctly the dependence of the heat transfer coefficient on liquid subcooling and flow rate; for some cases, however, heat transfer is still under-predicted, and an enhancement of the heat exchange from the liquid-vapour interface to the bulk of the liquid is required. The importance of the initial conditions at the quench front is also discussed. (orig.)
Analytical modeling of inverted annular film boiling
International Nuclear Information System (INIS)
Analytis, G.T.; Yadigaroglu, G.
1985-01-01
By employing a two-fluid formulation similar to the one used in the most recent LWR accident analysis codes, a model for the Inverted Annular Film Boiling region is developed. The conservation equations, together with appropriate constitutive relations are solved numerically and successful comparisons are made between model predictions and heat transfer coefficient distributions measured in a series of single-tube reflooding experiments. The model predicts generally correctly the dependence of the heat transfer coefficient on liquid subcooling and flow rate, through, for some cases, heat transfer is still under-predicted, and an enhancement of the heat exchange from the liquid-vapour interface to the bulk of the liquid is required
Energy Technology Data Exchange (ETDEWEB)
Vlach, Silvio Roberto Farias [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Inst. de Geociencias. Dept. de Mineralogia e Geotectonica], e-mail: srfvlach@usp.br
2010-03-15
Dating methodology by the electron probe microanalyser (EPMA) of (Th, U)-bearing minerals, highlighting monazite, acquired greater than ever importance in literature, particularly due to its superior spatial resolution, as well as versatility, which allow correlating petrological processes at times registered only in micro-scales in minerals and rocks with absolute ages. Although the accuracy is inferior to the one achieved with conventional isotopic methods in up to an order of magnitude, EPMA is the instrument that allows the best spatial resolution, reaching a few {mu}m{sup 3} in some conditions. Quantification of minor and trace elements with suitable precision and accuracy involves the own instrumental and analytical set-ups and data treatment strategies, significantly more rigorous when compared with those applied in conventional analyses. Th-U-Pb{sub T} dating is an example of these cases. Each EPMA is a unique machine as for its instrumental characteristics and respective automation system. In such a way, analytical procedures ought to be adjusted for laboratory specific cities. The analytical strategies and data treatment adopted in the Electronic Microprobe Laboratory from Instituto de Geociencias of Universidade de Sao Paulo, Brazil, with a JEOL JXA8600S EPMA, and a ThermoNoran-Voyager 4.3 automation system, are presented and compared with the ones used in other laboratories. The influence of instrumental factors and spectral overlaps on Th, U, and Pb quantification is discussed. Applied procedures to interference correction, error propagation, data treatment, and final chemical age presentation as well as to sampling and analyses are emphasized. Some typical applications are discussed, drawing attention to the most relevant aspects of electron microprobe dating. (author)
Unjamming in models with analytic pairwise potentials
Kooij, S.; Lerner, E.
Canonical models for studying the unjamming scenario in systems of soft repulsive particles assume pairwise potentials with a sharp cutoff in the interaction range. The sharp cutoff renders the potential nonanalytic but makes it possible to describe many properties of the solid in terms of the
A practical model for pressure probe system response estimation (with review of existing models)
Hall, B. F.; Povey, T.
2018-04-01
The accurate estimation of the unsteady response (bandwidth) of pneumatic pressure probe systems (probe, line and transducer volume) is a common practical problem encountered in the design of aerodynamic experiments. Understanding the bandwidth of the probe system is necessary to capture unsteady flow features accurately. Where traversing probes are used, the desired traverse speed and spatial gradients in the flow dictate the minimum probe system bandwidth required to resolve the flow. Existing approaches for bandwidth estimation are either complex or inaccurate in implementation, so probes are often designed based on experience. Where probe system bandwidth is characterized, it is often done experimentally, requiring careful experimental set-up and analysis. There is a need for a relatively simple but accurate model for estimation of probe system bandwidth. A new model is presented for the accurate estimation of pressure probe bandwidth for simple probes commonly used in wind tunnel environments; experimental validation is provided. An additional, simple graphical method for air is included for convenience.
Analytical and numerical modeling for flexible pipes
Wang, Wei; Chen, Geng
2011-12-01
The unbonded flexible pipe of eight layers, in which all the layers except the carcass layer are assumed to have isotropic properties, has been analyzed. Specifically, the carcass layer shows the orthotropic characteristics. The effective elastic moduli of the carcass layer have been developed in terms of the influence of deformation to stiffness. With consideration of the effective elastic moduli, the structure can be properly analyzed. Also the relative movements of tendons and relative displacements of wires in helical armour layer have been investigated. A three-dimensional nonlinear finite element model has been presented to predict the response of flexible pipes under axial force and torque. Further, the friction and contact of interlayer have been considered. Comparison between the finite element model and experimental results obtained in literature has been given and discussed, which might provide practical and technical support for the application of unbonded flexible pipes.
Haskell financial data modeling and predictive analytics
Ryzhov, Pavel
2013-01-01
This book is a hands-on guide that teaches readers how to use Haskell's tools and libraries to analyze data from real-world sources in an easy-to-understand manner.This book is great for developers who are new to financial data modeling using Haskell. A basic knowledge of functional programming is not required but will be useful. An interest in high frequency finance is essential.
Analytical model for screening potential CO2 repositories
Okwen, R.T.; Stewart, M.T.; Cunningham, J.A.
2011-01-01
Assessing potential repositories for geologic sequestration of carbon dioxide using numerical models can be complicated, costly, and time-consuming, especially when faced with the challenge of selecting a repository from a multitude of potential repositories. This paper presents a set of simple analytical equations (model), based on the work of previous researchers, that could be used to evaluate the suitability of candidate repositories for subsurface sequestration of carbon dioxide. We considered the injection of carbon dioxide at a constant rate into a confined saline aquifer via a fully perforated vertical injection well. The validity of the analytical model was assessed via comparison with the TOUGH2 numerical model. The metrics used in comparing the two models include (1) spatial variations in formation pressure and (2) vertically integrated brine saturation profile. The analytical model and TOUGH2 show excellent agreement in their results when similar input conditions and assumptions are applied in both. The analytical model neglects capillary pressure and the pressure dependence of fluid properties. However, simulations in TOUGH2 indicate that little error is introduced by these simplifications. Sensitivity studies indicate that the agreement between the analytical model and TOUGH2 depends strongly on (1) the residual brine saturation, (2) the difference in density between carbon dioxide and resident brine (buoyancy), and (3) the relationship between relative permeability and brine saturation. The results achieved suggest that the analytical model is valid when the relationship between relative permeability and brine saturation is linear or quasi-linear and when the irreducible saturation of brine is zero or very small. ?? 2011 Springer Science+Business Media B.V.
Analytical Model for High Impedance Fault Analysis in Transmission Lines
Directory of Open Access Journals (Sweden)
S. Maximov
2014-01-01
Full Text Available A high impedance fault (HIF normally occurs when an overhead power line physically breaks and falls to the ground. Such faults are difficult to detect because they often draw small currents which cannot be detected by conventional overcurrent protection. Furthermore, an electric arc accompanies HIFs, resulting in fire hazard, damage to electrical devices, and risk with human life. This paper presents an analytical model to analyze the interaction between the electric arc associated to HIFs and a transmission line. A joint analytical solution to the wave equation for a transmission line and a nonlinear equation for the arc model is presented. The analytical model is validated by means of comparisons between measured and calculated results. Several cases of study are presented which support the foundation and accuracy of the proposed model.
A physically based analytical spatial air temperature and humidity model
Yang Yang; Theodore A. Endreny; David J. Nowak
2013-01-01
Spatial variation of urban surface air temperature and humidity influences human thermal comfort, the settling rate of atmospheric pollutants, and plant physiology and growth. Given the lack of observations, we developed a Physically based Analytical Spatial Air Temperature and Humidity (PASATH) model. The PASATH model calculates spatial solar radiation and heat...
AN ANALYTIC MODEL OF DUSTY, STRATIFIED, SPHERICAL H ii REGIONS
Energy Technology Data Exchange (ETDEWEB)
Rodríguez-Ramírez, J. C.; Raga, A. C. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Ap. 70-543, 04510 D.F., México (Mexico); Lora, V. [Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität, Mönchhofstr. 12-14, D-69120 Heidelberg (Germany); Cantó, J., E-mail: juan.rodriguez@nucleares.unam.mx [Instituto de Astronomía, Universidad Nacional Autónoma de México, Ap. 70-468, 04510 D. F., México (Mexico)
2016-12-20
We study analytically the effect of radiation pressure (associated with photoionization processes and with dust absorption) on spherical, hydrostatic H ii regions. We consider two basic equations, one for the hydrostatic balance between the radiation-pressure components and the gas pressure, and another for the balance among the recombination rate, the dust absorption, and the ionizing photon rate. Based on appropriate mathematical approximations, we find a simple analytic solution for the density stratification of the nebula, which is defined by specifying the radius of the external boundary, the cross section of dust absorption, and the luminosity of the central star. We compare the analytic solution with numerical integrations of the model equations of Draine, and find a wide range of the physical parameters for which the analytic solution is accurate.
Four-parameter analytical local model potential for atoms
International Nuclear Information System (INIS)
Fei, Yu; Jiu-Xun, Sun; Rong-Gang, Tian; Wei, Yang
2009-01-01
Analytical local model potential for modeling the interaction in an atom reduces the computational effort in electronic structure calculations significantly. A new four-parameter analytical local model potential is proposed for atoms Li through Lr, and the values of four parameters are shell-independent and obtained by fitting the results of X a method. At the same time, the energy eigenvalues, the radial wave functions and the total energies of electrons are obtained by solving the radial Schrödinger equation with a new form of potential function by Numerov's numerical method. The results show that our new form of potential function is suitable for high, medium and low Z atoms. A comparison among the new potential function and other analytical potential functions shows the greater flexibility and greater accuracy of the present new potential function. (atomic and molecular physics)
Kaestner, M.; Cassiani, G.; Doeberl, G.; Braeckevelt, M.
2012-04-01
Conventional techniques for site characterization are time consuming, cost intensive, and do often not support decision making. Therefore, new techniques for a step by step site characterization strategy with smart feedback loops were developed in the framework of the ModelPROBE project: advanced geophysical site characterization techniques combined with new types of vegetation analysis (tree core monitoring), including integrated statistical analysis and modelling. Based on these non- to low invasive surveys, the extension of sources, contamination levels and soil heterogeneities can be localized. Hot spots can then be investigated by new direct push probing systems integrated with geophysical & hydrogeological methods, and combined with chemical & isotopic contaminant analysis for source localization and identification. The actually occurring bioprocesses, such as contaminant degradation or precipitation/mobilization processes, can be assessed using biosensors, in situ microcosms, and stable isotope and biomarker analysis. Some of these new techniques and tools were successfully evaluated against best practice of conventional methods at the fully equipped and characterized European reference sites available in the project. Beside scientific publications, the methods and techniques developed in the project will be provided in the form of an operation guideline handbook that will be published in September 2012. ModelPROBE (Grant No. 213161) is an EU project under the theme 6.3 Environmental Technologies 2007, 3.1.2.2.
Analytic uncertainty and sensitivity analysis of models with input correlations
Zhu, Yueying; Wang, Qiuping A.; Li, Wei; Cai, Xu
2018-03-01
Probabilistic uncertainty analysis is a common means of evaluating mathematical models. In mathematical modeling, the uncertainty in input variables is specified through distribution laws. Its contribution to the uncertainty in model response is usually analyzed by assuming that input variables are independent of each other. However, correlated parameters are often happened in practical applications. In the present paper, an analytic method is built for the uncertainty and sensitivity analysis of models in the presence of input correlations. With the method, it is straightforward to identify the importance of the independence and correlations of input variables in determining the model response. This allows one to decide whether or not the input correlations should be considered in practice. Numerical examples suggest the effectiveness and validation of our analytic method in the analysis of general models. A practical application of the method is also proposed to the uncertainty and sensitivity analysis of a deterministic HIV model.
Modeling the hysteresis of a scanning probe microscope
DEFF Research Database (Denmark)
Dirscherl, Kai; Garnæs, Jørgen; Nielsen, L.
2000-01-01
Most scanning probe microscopes use piezoelectric actuators in open loop configurations. Therefore a major problem related to these instruments is the image distortion due to the hysteresis effect of the piezo. In order to eliminate the distortions, cost effective software control based on a model....... The structures were scanned for different scan ranges varying from 5 V peak to peak to 440 V peak to peak, so that 99% of the scanners' full motion range was covered. A least-squares fit of the experiments to the hysteresis model provided standard deviations per scan range of around 0.2%. This represents...
The Cycle of Warfare - Analysis of an Analytical Model
DEFF Research Database (Denmark)
Jensen, Mikkel Storm
2016-01-01
The abstract has the title: “The Cycle of Warfare - Analysis of an Analytical Model” The Cycle of Warfare is an analytical model designed to illustrate the coherence between the organization, doctrine and technology of a military entity and the influence of the surrounding society as expressed...... both retrospectively and predictively. As a tool for historians the model can help to identify decisive factors in developments and outcomes. As a tool for intelligence analysts, it can be used predictively to identify likely possible outcomes or unknown elements in analysed entities....
An analytical model of the HINT performance metric
Energy Technology Data Exchange (ETDEWEB)
Snell, Q.O.; Gustafson, J.L. [Scalable Computing Lab., Ames, IA (United States)
1996-10-01
The HINT benchmark was developed to provide a broad-spectrum metric for computers and to measure performance over the full range of memory sizes and time scales. We have extended our understanding of why HINT performance curves look the way they do and can now predict the curves using an analytical model based on simple hardware specifications as input parameters. Conversely, by fitting the experimental curves with the analytical model, hardware specifications such as memory performance can be inferred to provide insight into the nature of a given computer system.
Surface potential modeling and reconstruction in Kelvin probe force microscopy.
Xu, Jie; Wu, Yangqing; Li, Wei; Xu, Jun
2017-09-08
Kelvin probe force microscopy (KPFM) measurement has been extensively applied in metallic, semiconductor and organic electronic or photovoltaic devices, to characterize the local contact potential difference or surface potential of the samples at the nanoscale. Here, a comprehensive modeling of surface potential in KPFM is established, from the well-known single capacitance model to a precise electrodynamic model, considering the long range property of the electrostatic force in KPFM. The limitations and relations of different models are also discussed. Besides, the feedback condition of the KPFM system is reconsidered and modified, showing that the influence of the cantilever has been overestimated by about 20% in previous reports. Afterwards, the surface potential of charged Si-nanocrystals is reconstructed based on the electrodynamic model, and the calculated surface charge density is very consistent with the macroscopic capacitance-voltage (C-V) measurement. A deep understanding and correct reconstruction of surface potential is crucial to the quantitative analysis of KPFM results.
Elliptic-cylindrical analytical flux-rope model for ICMEs
Nieves-Chinchilla, T.; Linton, M.; Hidalgo, M. A. U.; Vourlidas, A.
2016-12-01
We present an analytical flux-rope model for realistic magnetic structures embedded in Interplanetary Coronal Mass Ejections. The framework of this model was established by Nieves-Chinchilla et al. (2016) with the circular-cylindrical analytical flux rope model and under the concept developed by Hidalgo et al. (2002). Elliptic-cylindrical geometry establishes the first-grade of complexity of a series of models. The model attempts to describe the magnetic flux rope topology with distorted cross-section as a possible consequence of the interaction with the solar wind. In this model, the flux rope is completely described in the non-euclidean geometry. The Maxwell equations are solved using tensor calculus consistently with the geometry chosen, invariance along the axial component, and with the only assumption of no radial current density. The model is generalized in terms of the radial dependence of the poloidal current density component and axial current density component. The misalignment between current density and magnetic field is studied in detail for the individual cases of different pairs of indexes for the axial and poloidal current density components. This theoretical analysis provides a map of the force distribution inside of the flux-rope. The reconstruction technique has been adapted to the model and compared with in situ ICME set of events with different in situ signatures. The successful result is limited to some cases with clear in-situ signatures of distortion. However, the model adds a piece in the puzzle of the physical-analytical representation of these magnetic structures. Other effects such as axial curvature, expansion and/or interaction could be incorporated in the future to fully understand the magnetic structure. Finally, the mathematical formulation of this model opens the door to the next model: toroidal flux rope analytical model.
Analytical study on model tests of soil-structure interaction
International Nuclear Information System (INIS)
Odajima, M.; Suzuki, S.; Akino, K.
1987-01-01
Since nuclear power plant (NPP) structures are stiff, heavy and partly-embedded, the behavior of those structures during an earthquake depends on the vibrational characteristics of not only the structure but also the soil. Accordingly, seismic response analyses considering the effects of soil-structure interaction (SSI) are extremely important for seismic design of NPP structures. Many studies have been conducted on analytical techniques concerning SSI and various analytical models and approaches have been proposed. Based on the studies, SSI analytical codes (computer programs) for NPP structures have been improved at JINS (Japan Institute of Nuclear Safety), one of the departments of NUPEC (Nuclear Power Engineering Test Center) in Japan. These codes are soil-spring lumped-mass code (SANLUM), finite element code (SANSSI), thin layered element code (SANSOL). In proceeding with the improvement of the analytical codes, in-situ large-scale forced vibration SSI tests were performed using models simulating light water reactor buildings, and simulation analyses were performed to verify the codes. This paper presents an analytical study to demonstrate the usefulness of the codes
An analytical model for the assessment of airline expansion strategies
Directory of Open Access Journals (Sweden)
Mauricio Emboaba Moreira
2014-01-01
Full Text Available Purpose: The purpose of this article is to develop an analytical model to assess airline expansion strategies by combining generic business strategy models with airline business models. Methodology and approach: A number of airline business models are examined, as are Porter’s (1983 industry five forces that drive competition, complemented by Nalebuff/ Brandenburger’s (1996 sixth force, and the basic elements of the general environment in which the expansion process takes place. A system of points and weights is developed to create a score among the 904,736 possible combinations considered. The model’s outputs are generic expansion strategies with quantitative assessments for each specific combination of elements inputted. Originality and value: The analytical model developed is original because it combines for the first time and explicitly elements of the general environment, industry environment, airline business models and the generic expansion strategy types. Besides it creates a system of scores that may be used to drive the decision process toward the choice of a specific strategic expansion path. Research implications: The analytical model may be adapted to other industries apart from the airline industry by substituting the element “airline business model” by other industries corresponding elements related to the different specific business models.
An Analytical Model for Learning: An Applied Approach.
Kassebaum, Peter Arthur
A mediated-learning package, geared toward non-traditional students, was developed for use in the College of Marin's cultural anthropology courses. An analytical model for learning was used in the development of the package, utilizing concepts related to learning objectives, programmed instruction, Gestalt psychology, cognitive psychology, and…
MODEL ANALYTICAL NETWORK PROCESS (ANP DALAM PENGEMBANGAN PARIWISATA DI JEMBER
Directory of Open Access Journals (Sweden)
Sukidin Sukidin
2015-04-01
Full Text Available Abstrak : Model Analytical Network Process (ANP dalam Pengembangan Pariwisata di Jember. Penelitian ini mengkaji kebijakan pengembangan pariwisata di Jember, terutama kebijakan pengembangan agrowisata perkebunan kopi dengan menggunakan Jember Fashion Carnival (JFC sebagai event marketing. Metode yang digunakan adalah soft system methodology dengan menggunakan metode analitis jaringan (Analytical Network Process. Penelitian ini menemukan bahwa pengembangan pariwisata di Jember masih dilakukan dengan menggunakan pendekatan konvensional, belum terkoordinasi dengan baik, dan lebih mengandalkan satu even (atraksi pariwisata, yakni JFC, sebagai lokomotif daya tarik pariwisata Jember. Model pengembangan konvensional ini perlu dirancang kembali untuk memperoleh pariwisata Jember yang berkesinambungan. Kata kunci: pergeseran paradigma, industry pariwisata, even pariwisata, agrowisata Abstract: Analytical Network Process (ANP Model in the Tourism Development in Jember. The purpose of this study is to conduct a review of the policy of tourism development in Jember, especially development policies for coffee plantation agro-tourism by using Jember Fashion Carnival (JFC as event marketing. The research method used is soft system methodology using Analytical Network Process. The result shows that the tourism development in Jember is done using a conventional approach, lack of coordination, and merely focus on a single event tourism, i.e. the JFC, as locomotive tourism attraction in Jember. This conventional development model needs to be redesigned to reach Jember sustainable tourism development. Keywords: paradigm shift, tourism industry, agro-tourism
Piezoresistive Cantilever Performance—Part I: Analytical Model for Sensitivity
Park, Sung-Jin; Doll, Joseph C.; Pruitt, Beth L.
2010-01-01
An accurate analytical model for the change in resistance of a piezoresistor is necessary for the design of silicon piezoresistive transducers. Ion implantation requires a high-temperature oxidation or annealing process to activate the dopant atoms, and this treatment results in a distorted dopant profile due to diffusion. Existing analytical models do not account for the concentration dependence of piezoresistance and are not accurate for nonuniform dopant profiles. We extend previous analytical work by introducing two nondimensional factors, namely, the efficiency and geometry factors. A practical benefit of this efficiency factor is that it separates the process parameters from the design parameters; thus, designers may address requirements for cantilever geometry and fabrication process independently. To facilitate the design process, we provide a lookup table for the efficiency factor over an extensive range of process conditions. The model was validated by comparing simulation results with the experimentally determined sensitivities of piezoresistive cantilevers. We performed 9200 TSUPREM4 simulations and fabricated 50 devices from six unique process flows; we systematically explored the design space relating process parameters and cantilever sensitivity. Our treatment focuses on piezoresistive cantilevers, but the analytical sensitivity model is extensible to other piezoresistive transducers such as membrane pressure sensors. PMID:20336183
Synthesis and Analytical Centrifugation of Magnetic Model Colloids
Luigjes, B.
2012-01-01
This thesis is a study of the preparation and thermodynamic properties of magnetic colloids. First, two types of magnetic model colloids are investigated: composite colloids and single-domain nanoparticles. Thermodynamics of magnetic colloids is studied using analytical centrifugation, including a
Learning, Learning Analytics, Activity Visualisation and Open learner Model
DEFF Research Database (Denmark)
Bull, Susan; Kickmeier-Rust, Michael; Vatrapu, Ravi
2013-01-01
This paper draws on visualisation approaches in learning analytics, considering how classroom visualisations can come together in practice. We suggest an open learner model in situations where many tools and activity visualisations produce more visual information than can be readily interpreted....
Foam for Enhanced Oil Recovery : Modeling and Analytical Solutions
Ashoori, E.
2012-01-01
Foam increases sweep in miscible- and immiscible-gas enhanced oil recovery by decreasing the mobility of gas enormously. This thesis is concerned with the simulations and analytical solutions for foam flow for the purpose of modeling foam EOR in a reservoir. For the ultimate goal of upscaling our
Astrophysical Probes of New Models of Dark Matter
Zurek, Kathryn
One of the most pressing and relevant cosmological questions is on the nature of the dark matter. I propose a comprehensive program at the boundary of astrophysics and cosmology with particle physics, focused on the question on the nature of the Dark Matter (DM). Research at the boundary of the two fields is critically important as a plethora of experiments in both particle physics and astrophysics, such as direct and indirect detection of Dark Matter (DM) by the Fermi Gamma Ray Space Telescope (FGST), AMS-02, and Cosmic Microwave Background probes such as Planck, come online. At the same time, data from the Large Hadron Collider (LHC) will probe fundamental questions about Electroweak Symmetry Breaking and its implications for astrophysics and cosmology, as concerns especially the nature of the DM and the generation of the baryon asymmetry. Physics beyond the Standard Model (SM) is required to explain the astrophysical observation that DM dominates over ordinary matter by a ratio 5:1, as we learned through WMAP, as well as large scale structure surveys. Despite lacking an understanding of the properties of the DM, its presence is crucial for the formation of structure in the universe. Particle physics provides a framework for understanding what the DM could be. This proposal centers on building new models of DM, as well as studying their signatures both in the galaxy and on earth. While particle physics has provided a few popular candidates for DM (such as the supersymmetric neutralino), whose signatures have been extensively studied in the literature, it is important to consider other theoretically motivated candidates which provide distinct signatures. This proposal focuses on such new models of DM, especially models of DM from hidden sectors. For example, recently, the PAMELA experiment has observed a rise in the ratio of positron to electron flux at high energies. The flux may likely come from astrophysical objects nearby, such as pulsars. An intriguing
A New Analytical Model for Wind-Turbine Wakes
Bastankhah, Majid; Porté-Agel, Fernando
2013-04-01
The intention of this study is to propose and validate a simple and efficient analytical model for the prediction of the wake velocity downwind of a stand-alone wind-turbine. Extensive efforts have been carried out to model the wake region analytically. One of the most popular models, proposed by Jensen, assumes a top-hat distribution of the velocity deficit at any plane perpendicular to the wake. That model has been extensively used in the literature and commercial softwares, but it has two important limitations that should be pointed out: (a) Even though this model is supposed to satisfy momentum conservation, in reality mass conservation is only used to derive it; (b) the assumption of a top-hat distribution of the velocity deficit is expected to underestimate that deficit in the center of the wake, and overestimate it near the edge of the wake. In order to overcome the above-mentioned limitations, here we propose an alternative analytical model that satisfies both mass and momentum conservation, and assumes a Gaussian distribution of the velocity deficit. For this purpose, we apply momentum and mass conservation to two different control volumes which have been previously used in the context of analytical modeling of wakes. The velocity profiles obtained with our proposed model are in good agreement with large-eddy simulation data and experimental measurements. By contrast, the top hat models, as expected, clearly underestimate the velocity deficit at the center of the wake region and overestimate it near the edge of the wake.
New analytic results for speciation times in neutral models.
Gernhard, Tanja
2008-05-01
In this paper, we investigate the standard Yule model, and a recently studied model of speciation and extinction, the "critical branching process." We develop an analytic way-as opposed to the common simulation approach-for calculating the speciation times in a reconstructed phylogenetic tree. Simple expressions for the density and the moments of the speciation times are obtained. Methods for dating a speciation event become valuable, if for the reconstructed phylogenetic trees, no time scale is available. A missing time scale could be due to supertree methods, morphological data, or molecular data which violates the molecular clock. Our analytic approach is, in particular, useful for the model with extinction, since simulations of birth-death processes which are conditioned on obtaining n extant species today are quite delicate. Further, simulations are very time consuming for big n under both models.
Analytical model for nonlinear piezoelectric energy harvesting devices
International Nuclear Information System (INIS)
Neiss, S; Goldschmidtboeing, F; M Kroener; Woias, P
2014-01-01
In this work we propose analytical expressions for the jump-up and jump-down point of a nonlinear piezoelectric energy harvester. In addition, analytical expressions for the maximum power output at optimal resistive load and the 3 dB-bandwidth are derived. So far, only numerical models have been used to describe the physics of a piezoelectric energy harvester. However, this approach is not suitable to quickly evaluate different geometrical designs or piezoelectric materials in the harvester design process. In addition, the analytical expressions could be used to predict the jump-frequencies of a harvester during operation. In combination with a tuning mechanism, this would allow the design of an efficient control algorithm to ensure that the harvester is always working on the oscillator's high energy attractor. (paper)
Analytic solution of the Starobinsky model for inflation
Energy Technology Data Exchange (ETDEWEB)
Paliathanasis, Andronikos [Universidad Austral de Chile, Instituto de Ciencias Fisicas y Matematicas, Valdivia (Chile); Durban University of Technology, Institute of Systems Science, Durban (South Africa)
2017-07-15
We prove that the field equations of the Starobinsky model for inflation in a Friedmann-Lemaitre-Robertson-Walker metric constitute an integrable system. The analytical solution in terms of a Painleve series for the Starobinsky model is presented for the case of zero and nonzero spatial curvature. In both cases the leading-order term describes the radiation era provided by the corresponding higher-order theory. (orig.)
Collaborative data analytics for smart buildings: opportunities and models
DEFF Research Database (Denmark)
Lazarova-Molnar, Sanja; Mohamed, Nader
2018-01-01
Smart buildings equipped with state-of-the-art sensors and meters are becoming more common. Large quantities of data are being collected by these devices. For a single building to benefit from its own collected data, it will need to wait for a long time to collect sufficient data to build accurate...... models to help improve the smart buildings systems. Therefore, multiple buildings need to cooperate to amplify the benefits from the collected data and speed up the model building processes. Apparently, this is not so trivial and there are associated challenges. In this paper, we study the importance...... of collaborative data analytics for smart buildings, its benefits, as well as presently possible models of carrying it out. Furthermore, we present a framework for collaborative fault detection and diagnosis as a case of collaborative data analytics for smart buildings. We also provide a preliminary analysis...
Analytical heat transfer modeling of a new radiation calorimeter
Energy Technology Data Exchange (ETDEWEB)
Obame Ndong, Elysée [Department of Industrial Engineering and Maintenance, University of Sciences and Technology of Masuku (USTM), BP 941 Franceville (Gabon); Grenoble Electrical Engineering Laboratory (G2Elab), University Grenoble Alpes and CNRS, G2Elab, F38000 Grenoble (France); Gallot-Lavallée, Olivier [Grenoble Electrical Engineering Laboratory (G2Elab), University Grenoble Alpes and CNRS, G2Elab, F38000 Grenoble (France); Aitken, Frédéric, E-mail: frederic.aitken@g2elab.grenoble-inp.fr [Grenoble Electrical Engineering Laboratory (G2Elab), University Grenoble Alpes and CNRS, G2Elab, F38000 Grenoble (France)
2016-06-10
Highlights: • Design of a new calorimeter for measuring heat power loss in electrical components. • The calorimeter can operate in a temperature range from −50 °C to 150 °C. • An analytical model of heat transfers for this new calorimeter is presented. • The theoretical sensibility of the new apparatus is estimated at ±1 mW. - Abstract: This paper deals with an analytical modeling of heat transfers simulating a new radiation calorimeter operating in a temperature range from −50 °C to 150 °C. The aim of this modeling is the evaluation of the feasibility and performance of the calorimeter by assessing the measurement of power losses of some electrical devices by radiation, the influence of the geometry and materials. Finally a theoretical sensibility of the new apparatus is estimated at ±1 mW. From these results the calorimeter has been successfully implemented and patented.
Analytical Modeling for the Grating Eddy Current Displacement Sensors
Directory of Open Access Journals (Sweden)
Lv Chunfeng
2015-02-01
Full Text Available As a new type of displacement sensor, grating eddy current displacement sensor (GECDS combines traditional eddy current sensors and grating structure in one. The GECDS performs a wide range displacement measurement without precision reduction. This paper proposes an analytical modeling approach for the GECDS. The solution model is established in the Cartesian coordinate system, and the solving domain is limited to finite extents by using the truncated region eigenfunction expansion method. Based on the second order vector potential, expressions for the electromagnetic field as well as coil impedance related to the displacement can be expressed in closed-form. Theoretical results are then confirmed by experiments, which prove the suitability and effectiveness of the analytical modeling approach.
Analytical heat transfer modeling of a new radiation calorimeter
International Nuclear Information System (INIS)
Obame Ndong, Elysée; Gallot-Lavallée, Olivier; Aitken, Frédéric
2016-01-01
Highlights: • Design of a new calorimeter for measuring heat power loss in electrical components. • The calorimeter can operate in a temperature range from −50 °C to 150 °C. • An analytical model of heat transfers for this new calorimeter is presented. • The theoretical sensibility of the new apparatus is estimated at ±1 mW. - Abstract: This paper deals with an analytical modeling of heat transfers simulating a new radiation calorimeter operating in a temperature range from −50 °C to 150 °C. The aim of this modeling is the evaluation of the feasibility and performance of the calorimeter by assessing the measurement of power losses of some electrical devices by radiation, the influence of the geometry and materials. Finally a theoretical sensibility of the new apparatus is estimated at ±1 mW. From these results the calorimeter has been successfully implemented and patented.
Roll levelling semi-analytical model for process optimization
Silvestre, E.; Garcia, D.; Galdos, L.; Saenz de Argandoña, E.; Mendiguren, J.
2016-08-01
Roll levelling is a primary manufacturing process used to remove residual stresses and imperfections of metal strips in order to make them suitable for subsequent forming operations. In the last years the importance of this process has been evidenced with the apparition of Ultra High Strength Steels with strength > 900 MPa. The optimal setting of the machine as well as a robust machine design has become critical for the correct processing of these materials. Finite Element Method (FEM) analysis is the widely used technique for both aspects. However, in this case, the FEM simulation times are above the admissible ones in both machine development and process optimization. In the present work, a semi-analytical model based on a discrete bending theory is presented. This model is able to calculate the critical levelling parameters i.e. force, plastification rate, residual stresses in a few seconds. First the semi-analytical model is presented. Next, some experimental industrial cases are analyzed by both the semi-analytical model and the conventional FEM model. Finally, results and computation times of both methods are compared.
Semantic Interaction for Sensemaking: Inferring Analytical Reasoning for Model Steering.
Endert, A; Fiaux, P; North, C
2012-12-01
Visual analytic tools aim to support the cognitively demanding task of sensemaking. Their success often depends on the ability to leverage capabilities of mathematical models, visualization, and human intuition through flexible, usable, and expressive interactions. Spatially clustering data is one effective metaphor for users to explore similarity and relationships between information, adjusting the weighting of dimensions or characteristics of the dataset to observe the change in the spatial layout. Semantic interaction is an approach to user interaction in such spatializations that couples these parametric modifications of the clustering model with users' analytic operations on the data (e.g., direct document movement in the spatialization, highlighting text, search, etc.). In this paper, we present results of a user study exploring the ability of semantic interaction in a visual analytic prototype, ForceSPIRE, to support sensemaking. We found that semantic interaction captures the analytical reasoning of the user through keyword weighting, and aids the user in co-creating a spatialization based on the user's reasoning and intuition.
ADVAN-style analytical solutions for common pharmacokinetic models.
Abuhelwa, Ahmad Y; Foster, David J R; Upton, Richard N
2015-01-01
The analytical solutions to compartmental pharmacokinetic models are well known, but have not been presented in a form that easily allows for complex dosing regimen and changes in covariate/parameter values that may occur at discrete times within and/or between dosing intervals. Laplace transforms were used to derive ADVAN-style analytical solutions for 1, 2, and 3 compartment pharmacokinetic linear models of intravenous and first-order absorption drug administration. The equations calculate the change in drug amounts in each compartment of the model over a time interval (t; t = t2 - t1) accounting for any dose or covariate events acting in the time interval. The equations were coded in the R language and used to simulate the time-course of drug amounts in each compartment of the systems. The equations were validated against commercial software [NONMEM (Beal, Sheiner, Boeckmann, & Bauer, 2009)] output to assess their capability to handle both complex dosage regimens and the effect of changes in covariate/parameter values that may occur at discrete times within or between dosing intervals. For all tested pharmacokinetic models, the time-course of drug amounts using the ADVAN-style analytical solutions were identical to NONMEM outputs to at least four significant figures, confirming the validity of the presented equations. To our knowledge, this paper presents the ADVAN-style equations for common pharmacokinetic models in the literature for the first time. The presented ADVAN-style equations overcome obstacles to implementing the classical analytical solutions in software, and have speed advantages over solutions using differential equation solvers. The equations presented in this paper fill a gap in the pharmacokinetic literature, and it is expected that these equations will facilitate the investigation of useful open-source software for modelling pharmacokinetic data. Copyright © 2015 Elsevier Inc. All rights reserved.
Detecting Clusters in Atom Probe Data with Gaussian Mixture Models.
Zelenty, Jennifer; Dahl, Andrew; Hyde, Jonathan; Smith, George D W; Moody, Michael P
2017-04-01
Accurately identifying and extracting clusters from atom probe tomography (APT) reconstructions is extremely challenging, yet critical to many applications. Currently, the most prevalent approach to detect clusters is the maximum separation method, a heuristic that relies heavily upon parameters manually chosen by the user. In this work, a new clustering algorithm, Gaussian mixture model Expectation Maximization Algorithm (GEMA), was developed. GEMA utilizes a Gaussian mixture model to probabilistically distinguish clusters from random fluctuations in the matrix. This machine learning approach maximizes the data likelihood via expectation maximization: given atomic positions, the algorithm learns the position, size, and width of each cluster. A key advantage of GEMA is that atoms are probabilistically assigned to clusters, thus reflecting scientifically meaningful uncertainty regarding atoms located near precipitate/matrix interfaces. GEMA outperforms the maximum separation method in cluster detection accuracy when applied to several realistically simulated data sets. Lastly, GEMA was successfully applied to real APT data.
Using Learning Analytics to Understand Scientific Modeling in the Classroom
Directory of Open Access Journals (Sweden)
David Quigley
2017-11-01
Full Text Available Scientific models represent ideas, processes, and phenomena by describing important components, characteristics, and interactions. Models are constructed across various scientific disciplines, such as the food web in biology, the water cycle in Earth science, or the structure of the solar system in astronomy. Models are central for scientists to understand phenomena, construct explanations, and communicate theories. Constructing and using models to explain scientific phenomena is also an essential practice in contemporary science classrooms. Our research explores new techniques for understanding scientific modeling and engagement with modeling practices. We work with students in secondary biology classrooms as they use a web-based software tool—EcoSurvey—to characterize organisms and their interrelationships found in their local ecosystem. We use learning analytics and machine learning techniques to answer the following questions: (1 How can we automatically measure the extent to which students’ scientific models support complete explanations of phenomena? (2 How does the design of student modeling tools influence the complexity and completeness of students’ models? (3 How do clickstreams reflect and differentiate student engagement with modeling practices? We analyzed EcoSurvey usage data collected from two different deployments with over 1,000 secondary students across a large urban school district. We observe large variations in the completeness and complexity of student models, and large variations in their iterative refinement processes. These differences reveal that certain key model features are highly predictive of other aspects of the model. We also observe large differences in student modeling practices across different classrooms and teachers. We can predict a student’s teacher based on the observed modeling practices with a high degree of accuracy without significant tuning of the predictive model. These results highlight
SINGLE PHASE ANALYTICAL MODELS FOR TERRY TURBINE NOZZLE
Energy Technology Data Exchange (ETDEWEB)
Zhao, Haihua; Zhang, Hongbin; Zou, Ling; O' Brien, James
2016-11-01
All BWR RCIC (Reactor Core Isolation Cooling) systems and PWR AFW (Auxiliary Feed Water) systems use Terry turbine, which is composed of the wheel with turbine buckets and several groups of fixed nozzles and reversing chambers inside the turbine casing. The inlet steam is accelerated through the turbine nozzle and impacts on the wheel buckets, generating work to drive the RCIC pump. As part of the efforts to understand the unexpected “self-regulating” mode of the RCIC systems in Fukushima accidents and extend BWR RCIC and PWR AFW operational range and flexibility, mechanistic models for the Terry turbine, based on Sandia National Laboratories’ original work, has been developed and implemented in the RELAP-7 code to simulate the RCIC system. RELAP-7 is a new reactor system code currently under development with the funding support from U.S. Department of Energy. The RELAP-7 code is a fully implicit code and the preconditioned Jacobian-free Newton-Krylov (JFNK) method is used to solve the discretized nonlinear system. This paper presents a set of analytical models for simulating the flow through the Terry turbine nozzles when inlet fluid is pure steam. The implementation of the models into RELAP-7 will be briefly discussed. In the Sandia model, the turbine bucket inlet velocity is provided according to a reduced-order model, which was obtained from a large number of CFD simulations. In this work, we propose an alternative method, using an under-expanded jet model to obtain the velocity and thermodynamic conditions for the turbine bucket inlet. The models include both adiabatic expansion process inside the nozzle and free expansion process out of the nozzle to reach the ambient pressure. The combined models are able to predict the steam mass flow rate and supersonic velocity to the Terry turbine bucket entrance, which are the necessary input conditions for the Terry Turbine rotor model. The nozzle analytical models were validated with experimental data and
An Analytical Tire Model with Flexible Carcass for Combined Slips
Directory of Open Access Journals (Sweden)
Nan Xu
2014-01-01
Full Text Available The tire mechanical characteristics under combined cornering and braking/driving situations have significant effects on vehicle directional controls. The objective of this paper is to present an analytical tire model with flexible carcass for combined slip situations, which can describe tire behavior well and can also be used for studying vehicle dynamics. The tire forces and moments come mainly from the shear stress and sliding friction at the tread-road interface. In order to describe complicated tire characteristics and tire-road friction, some key factors are considered in this model: arbitrary pressure distribution; translational, bending, and twisting compliance of the carcass; dynamic friction coefficient; anisotropic stiffness properties. The analytical tire model can describe tire forces and moments accurately under combined slip conditions. Some important properties induced by flexible carcass can also be reflected. The structural parameters of a tire can be identified from tire measurements and the computational results using the analytical model show good agreement with test data.
The Scanning Theremin Microscope: A Model Scanning Probe Instrument for Hands-On Activities
Quardokus, Rebecca C.; Wasio, Natalie A.; Kandel, S. Alex
2014-01-01
A model scanning probe microscope, designed using similar principles of operation to research instruments, is described. Proximity sensing is done using a capacitance probe, and a mechanical linkage is used to scan this probe across surfaces. The signal is transduced as an audio tone using a heterodyne detection circuit analogous to that used in…
Probing the inert doublet dark matter model with Cherenkov telescopes
Energy Technology Data Exchange (ETDEWEB)
Garcia-Cely, Camilo [Service de Physique Théorique, CP225, Université Libre de Bruxelles, Bld du Triomphe, Brussels, 1050 Belgium (Belgium); Gustafsson, Michael [Institute for theoretical Physics—Faculty of Physics, Georg-August University Göttingen, Friedrich-Hund-Platz 1, Göttingen, D-37077 Germany (Germany); Ibarra, Alejandro, E-mail: cgarciac@ulb.ac.be, E-mail: michael.gustafsson@theorie.physik.uni-goettingen.de, E-mail: alejandro.ibarra@ph.tum.de [Physik-Department T30d, Technische Universität München, James-Franck-Straße, Garching, D-85748 Germany (Germany)
2016-02-01
We present a detailed study of the annihilation signals of the inert dark matter doublet model in its high mass regime. Concretely, we study the prospects to observe gamma-ray signals of the model in current and projected Cherenkov telescopes taking into account the Sommerfeld effect and including the contribution to the spectrum from gamma-ray lines as well as from internal bremsstrahlung. We show that present observations of the galactic center by the H.E.S.S. instrument are able to exclude regions of the parameter space that give the correct dark matter relic abundance. In particular, models with the charged and the neutral components of the inert doublet nearly degenerate in mass have strong gamma-ray signals. Furthermore, for dark matter particle masses above 1 TeV, we find that the non-observation of the continuum of photons generated by the hadronization of the annihilation products typically give stronger constraints on the model parameters than the sharp spectral features associated to annihilation into monochromatic photons and the internal bremsstrahlung process. Lastly, we also analyze the interplay between indirect and direct detection searches for this model, concluding that the prospects for the former are more promising. In particular, we find that the upcoming Cherenkov Telescope Array will be able to probe a significant part of the high mass regime of the model.
A simple stationary semi-analytical wake model
DEFF Research Database (Denmark)
Larsen, Gunner Chr.
We present an idealized simple, but fast, semi-analytical algorithm for computation of stationary wind farm wind fields with a possible potential within a multi-fidelity strategy for wind farm topology optimization. Basically, the model considers wakes as linear perturbations on the ambient non...... rotationally symmetric, and the rotor inflow fields are consistently assumed uniform. Expansion of stationary wake fields is believed to be significantly affected by meandering of wake deficits as e.g. described by the Dynamic Wake Meandering model. In the present context, this effect is approximately...... conditions are imposed), the present formulation of wake expansion is believed to underestimate wake expansion, because the analytical wake formulation dictates the wake expansion to behave as x1/3 with downstream distance, whereas wake expansion as primary controlled by wake meandering develops...
Human performance modeling for system of systems analytics.
Energy Technology Data Exchange (ETDEWEB)
Dixon, Kevin R.; Lawton, Craig R.; Basilico, Justin Derrick; Longsine, Dennis E. (INTERA, Inc., Austin, TX); Forsythe, James Chris; Gauthier, John Henry; Le, Hai D.
2008-10-01
A Laboratory-Directed Research and Development project was initiated in 2005 to investigate Human Performance Modeling in a System of Systems analytic environment. SAND2006-6569 and SAND2006-7911 document interim results from this effort; this report documents the final results. The problem is difficult because of the number of humans involved in a System of Systems environment and the generally poorly defined nature of the tasks that each human must perform. A two-pronged strategy was followed: one prong was to develop human models using a probability-based method similar to that first developed for relatively well-understood probability based performance modeling; another prong was to investigate more state-of-art human cognition models. The probability-based modeling resulted in a comprehensive addition of human-modeling capability to the existing SoSAT computer program. The cognitive modeling resulted in an increased understanding of what is necessary to incorporate cognition-based models to a System of Systems analytic environment.
Two dimensional analytical model for a reconfigurable field effect transistor
Ranjith, R.; Jayachandran, Remya; Suja, K. J.; Komaragiri, Rama S.
2018-02-01
This paper presents two-dimensional potential and current models for a reconfigurable field effect transistor (RFET). Two potential models which describe subthreshold and above-threshold channel potentials are developed by solving two-dimensional (2D) Poisson's equation. In the first potential model, 2D Poisson's equation is solved by considering constant/zero charge density in the channel region of the device to get the subthreshold potential characteristics. In the second model, accumulation charge density is considered to get above-threshold potential characteristics of the device. The proposed models are applicable for the device having lightly doped or intrinsic channel. While obtaining the mathematical model, whole body area is divided into two regions: gated region and un-gated region. The analytical models are compared with technology computer-aided design (TCAD) simulation results and are in complete agreement for different lengths of the gated regions as well as at various supply voltage levels.
Analytic solution of a five-direction radiation transport model
International Nuclear Information System (INIS)
Cramer, S.N.
1988-01-01
In order to test certain spatial and angular dependent Monte Carlo biasing techniques, a one-dimensional, one energy, two-media, five-direction radiation transport model has been devised for which an analytic solution exists. Although this solution is too long to be conveniently expressed in an explicit form, it can be easily evaluated on the smallest of computers. This solution is discussed in this paper. 1 ref
New analytically solvable models of relativistic point interactions
International Nuclear Information System (INIS)
Gesztesy, F.; Seba, P.
1987-01-01
Two new analytically solvable models of relativistic point interactions in one dimension (being natural extensions of the nonrelativistic δ-resp, δ'-interaction) are considered. Their spectral properties in the case of finitely many point interactions as well as in the periodic case are fully analyzed. Moreover the spectrum is explicitely determined in the case of independent, identically distributed random coupling constants and the analog of the Saxon and Huther conjecture concerning gaps in the energy spectrum of such systems is derived
An analytical thermohydraulic model for discretely fractured geothermal reservoirs
Fox, Don B.; Koch, Donald L.; Tester, Jefferson W.
2016-09-01
In discretely fractured reservoirs such as those found in Enhanced/Engineered Geothermal Systems (EGS), knowledge of the fracture network is important in understanding the thermal hydraulics, i.e., how the fluid flows and the resulting temporal evolution of the subsurface temperature. The purpose of this study was to develop an analytical model of the fluid flow and heat transport in a discretely fractured network that can be used for a wide range of modeling applications and serve as an alternative analysis tool to more computationally intensive numerical codes. Given the connectivity and structure of a fracture network, the flow in the system was solved using a linear system of algebraic equations for the pressure at the nodes of the network. With the flow determined, the temperature in the fracture was solved by coupling convective heat transport in the fracture with one-dimensional heat conduction perpendicular to the fracture, employing the Green's function derived solution for a single discrete fracture. The predicted temperatures along the fracture surfaces from the analytical solution were compared to numerical simulations using the TOUGH2 reservoir code. Through two case studies, we showed the capabilities of the analytical model and explored the effect of uncertainty in the fracture apertures and network structure on thermal performance. While both sources of uncertainty independently produce large variations in production temperature, uncertainty in the network structure, whenever present, had a predominant influence on thermal performance.
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
A Hybrid Computational and Analytical Model of Irrigation Drip emitters
Narain, Jaya; Winter, V., Amos
2017-11-01
This paper details a hybrid computational and analytical model to predict the performance of inline pressure-compensating drip irrigation emitters, devices used to accurately meter water to crops. Flow rate is controlled in the emitter by directing the water through a tortuous path, and then through a variable resistor composed of a flexible membrane that deflects under changes in pressure, restricting the flow path. An experimentally validated computational fluid dynamics model was used to derive a resistance factor that characterizes flow behavior through a tortuous path. Expressions describing the bending mechanics of the membrane were combined with analytical fluid flow models to iteratively predict flow behavior through the variable resistor. The hybrid model reduces the computational time as compared to purely computational methods, lowering the time required to iterate and select optimal designs. The model was validated using three commercially available drip emitters, rated at 1.1, 2, and 3.8 L/hr. For each, the model accurately predicted flow rate versus pressure behavior within a 95% confidence interval of experimental data and accurately replicated the performance stated by the manufacturer. Jain Irrigation, NSF GRFP.
Model and Analytic Processes for Export License Assessments
Energy Technology Data Exchange (ETDEWEB)
Thompson, Sandra E.; Whitney, Paul D.; Weimar, Mark R.; Wood, Thomas W.; Daly, Don S.; Brothers, Alan J.; Sanfilippo, Antonio P.; Cook, Diane; Holder, Larry
2011-09-29
This paper represents the Department of Energy Office of Nonproliferation Research and Development (NA-22) Simulations, Algorithms and Modeling (SAM) Program's first effort to identify and frame analytical methods and tools to aid export control professionals in effectively predicting proliferation intent; a complex, multi-step and multi-agency process. The report focuses on analytical modeling methodologies that alone, or combined, may improve the proliferation export control license approval process. It is a follow-up to an earlier paper describing information sources and environments related to international nuclear technology transfer. This report describes the decision criteria used to evaluate modeling techniques and tools to determine which approaches will be investigated during the final 2 years of the project. The report also details the motivation for why new modeling techniques and tools are needed. The analytical modeling methodologies will enable analysts to evaluate the information environment for relevance to detecting proliferation intent, with specific focus on assessing risks associated with transferring dual-use technologies. Dual-use technologies can be used in both weapons and commercial enterprises. A decision-framework was developed to evaluate which of the different analytical modeling methodologies would be most appropriate conditional on the uniqueness of the approach, data availability, laboratory capabilities, relevance to NA-22 and Office of Arms Control and Nonproliferation (NA-24) research needs and the impact if successful. Modeling methodologies were divided into whether they could help micro-level assessments (e.g., help improve individual license assessments) or macro-level assessment. Macro-level assessment focuses on suppliers, technology, consumers, economies, and proliferation context. Macro-level assessment technologies scored higher in the area of uniqueness because less work has been done at the macro level. An
Collisionless magnetic reconnection: analytical model and PIC simulation comparison
Directory of Open Access Journals (Sweden)
V. Semenov
2009-03-01
Full Text Available Magnetic reconnection is believed to be responsible for various explosive processes in the space plasma including magnetospheric substorms. The Hall effect is proved to play a key role in the reconnection process. An analytical model of steady-state magnetic reconnection in a collisionless incompressible plasma is developed using the electron Hall MHD approximation. It is shown that the initial complicated system of equations may split into a system of independent equations, and the solution of the problem is based on the Grad-Shafranov equation for the magnetic potential. The results of the analytical study are further compared with a two-dimensional particle-in-cell simulation of reconnection. It is shown that both methods demonstrate a close agreement in the electron current and the magnetic and electric field structures obtained. The spatial scales of the acceleration region in the simulation and the analytical study are of the same order. Such features like particles trajectories and the in-plane electric field structure appear essentially similar in both models.
HTS axial flux induction motor with analytic and FEA modeling
International Nuclear Information System (INIS)
Li, S.; Fan, Y.; Fang, J.; Qin, W.; Lv, G.; Li, J.H.
2013-01-01
Highlights: •A high temperature superconductor axial flux induction motor and a novel maglev scheme are presented. •Analytic method and finite element method have been adopted to model the motor and to calculate the force. •Magnetic field distribution in HTS coil is calculated by analytic method. •An effective method to improve the critical current of HTS coil is presented. •AC losses of HTS coils in the HTS axial flux induction motor are estimated and tested. -- Abstract: This paper presents a high-temperature superconductor (HTS) axial-flux induction motor, which can output levitation force and torque simultaneously. In order to analyze the character of the force, analytic method and finite element method are adopted to model the motor. To make sure the HTS can carry sufficiently large current and work well, the magnetic field distribution in HTS coil is calculated. An effective method to improve the critical current of HTS coil is presented. Then, AC losses in HTS windings in the motor are estimated and tested
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
Analytical models of optical response in one-dimensional semiconductors
International Nuclear Information System (INIS)
Pedersen, Thomas Garm
2015-01-01
The quantum mechanical description of the optical properties of crystalline materials typically requires extensive numerical computation. Including excitonic and non-perturbative field effects adds to the complexity. In one dimension, however, the analysis simplifies and optical spectra can be computed exactly. In this paper, we apply the Wannier exciton formalism to derive analytical expressions for the optical response in four cases of increasing complexity. Thus, we start from free carriers and, in turn, switch on electrostatic fields and electron–hole attraction and, finally, analyze the combined influence of these effects. In addition, the optical response of impurity-localized excitons is discussed. - Highlights: • Optical response of one-dimensional semiconductors including excitons. • Analytical model of excitonic Franz–Keldysh effect. • Computation of optical response of impurity-localized excitons
Analytical modelling of hydrogen transport in reactor containments
International Nuclear Information System (INIS)
Manno, V.P.
1983-09-01
A versatile computational model of hydrogen transport in nuclear plant containment buildings is developed. The background and significance of hydrogen-related nuclear safety issues are discussed. A computer program is constructed that embodies the analytical models. The thermofluid dynamic formulation spans a wide applicability range from rapid two-phase blowdown transients to slow incompressible hydrogen injection. Detailed ancillary models of molecular and turbulent diffusion, mixture transport properties, multi-phase multicomponent thermodynamics and heat sink modelling are addressed. The numerical solution of the continuum equations emphasizes both accuracy and efficiency in the employment of relatively coarse discretization and long time steps. Reducing undesirable numerical diffusion is addressed. Problem geometry options include lumped parameter zones, one dimensional meshs, two dimensional Cartesian or axisymmetric coordinate systems and three dimensional Cartesian or cylindrical regions. An efficient lumped nodal model is included for simulation of events in which spatial resolution is not significant. Several validation calculations are reported
Analytical expressions for transition edge sensor excess noise models
International Nuclear Information System (INIS)
Brandt, Daniel; Fraser, George W.
2010-01-01
Transition edge sensors (TESs) are high-sensitivity thermometers used in cryogenic microcalorimeters which exploit the steep gradient in resistivity with temperature during the superconducting phase transition. Practical TES devices tend to exhibit a white noise of uncertain origin, arising inside the device. We discuss two candidate models for this excess noise, phase slip shot noise (PSSN) and percolation noise. We extend the existing PSSN model to include a magnetic field dependence and derive a basic analytical model for percolation noise. We compare the predicted functional forms of the noise current vs. resistivity curves of both models with experimental data and provide a set of equations for both models to facilitate future experimental efforts to clearly identify the source of excess noise.
Kuznetsova, Irina M.; Povarova, Olga; Stepanenko, Olesya; Turoverov, Konstantin K.; Crescenzo, Roberta; Varriale, Antonio; Staiano, Maria; D'Auria, Sabato
2007-06-01
Glucose sensing and odorant molecules sensing are used as a models to explore the advantages and problems deriving from the use of either enzymes or odorant-binding proteins to develop stable optical biosensors. We report on a novel approach to address the problem of substrate consumption by sensors based on enzymes, namely the utilization of apoenzymes as non-active forms of the protein which are still able to bind the substrate/ligand. We also show studies in which the isolation of an odorant-binding protein from the nose of the dog is used as non-consuming analyte probe for the realization of an integrated optical sensor.
Synthetic Empirical Chorus Wave Model From Combined Van Allen Probes and Cluster Statistics
Agapitov, O. V.; Mourenas, D.; Artemyev, A. V.; Mozer, F. S.; Hospodarsky, G.; Bonnell, J.; Krasnoselskikh, V.
2018-01-01
Chorus waves are among the most important natural electromagnetic emissions in the magnetosphere as regards to their potential effects on electron dynamics. They can efficiently accelerate or precipitate electrons trapped in the outer radiation belt, producing either fast increases of relativistic particle fluxes or auroras at high latitudes. Accurately modeling their effects, however, requires detailed models of their wave power and obliquity distribution as a function of geomagnetic activity in a particularly wide spatial domain, rarely available based solely on the statistics obtained from only one satellite mission. Here we seize the opportunity of synthesizing data from the Van Allen Probes and Cluster spacecraft to provide a new comprehensive chorus wave model in the outer radiation belt. The respective spatial coverages of these two missions are shown to be especially complementary and further allow a good cross calibration in the overlap domain. We used 4 years (2012-2016) of Van Allen Probes VLF data in the chorus frequency range up to 12 kHz at latitudes lower than 20°, combined with 10 years of Cluster VLF measurements up to 4 kHz in order to provide a full coverage of geomagnetic latitudes up to 45° in the chorus frequency range 0.1fce-0.8fce. The resulting synthetic statistical model of chorus wave amplitude, obliquity, and frequency is presented in the form of analytical functions of latitude and Kp in three different magnetic local time sectors and for two ranges of L shells outside the plasmasphere. Such a synthetic and reliable chorus model is crucially important for accurately modeling global acceleration and loss of electrons over the long run in the outer radiation belt, allowing a comprehensive description of electron flux variations over a very wide energy range.
Analytical model of reactive transport processes with spatially variable coefficients.
Simpson, Matthew J; Morrow, Liam C
2015-05-01
Analytical solutions of partial differential equation (PDE) models describing reactive transport phenomena in saturated porous media are often used as screening tools to provide insight into contaminant fate and transport processes. While many practical modelling scenarios involve spatially variable coefficients, such as spatially variable flow velocity, v(x), or spatially variable decay rate, k(x), most analytical models deal with constant coefficients. Here we present a framework for constructing exact solutions of PDE models of reactive transport. Our approach is relevant for advection-dominant problems, and is based on a regular perturbation technique. We present a description of the solution technique for a range of one-dimensional scenarios involving constant and variable coefficients, and we show that the solutions compare well with numerical approximations. Our general approach applies to a range of initial conditions and various forms of v(x) and k(x). Instead of simply documenting specific solutions for particular cases, we present a symbolic worksheet, as supplementary material, which enables the solution to be evaluated for different choices of the initial condition, v(x) and k(x). We also discuss how the technique generalizes to apply to models of coupled multispecies reactive transport as well as higher dimensional problems.
Analytical modeling of glucose biosensors based on carbon nanotubes.
Pourasl, Ali H; Ahmadi, Mohammad Taghi; Rahmani, Meisam; Chin, Huei Chaeng; Lim, Cheng Siong; Ismail, Razali; Tan, Michael Loong Peng
2014-01-15
In recent years, carbon nanotubes have received widespread attention as promising carbon-based nanoelectronic devices. Due to their exceptional physical, chemical, and electrical properties, namely a high surface-to-volume ratio, their enhanced electron transfer properties, and their high thermal conductivity, carbon nanotubes can be used effectively as electrochemical sensors. The integration of carbon nanotubes with a functional group provides a good and solid support for the immobilization of enzymes. The determination of glucose levels using biosensors, particularly in the medical diagnostics and food industries, is gaining mass appeal. Glucose biosensors detect the glucose molecule by catalyzing glucose to gluconic acid and hydrogen peroxide in the presence of oxygen. This action provides high accuracy and a quick detection rate. In this paper, a single-wall carbon nanotube field-effect transistor biosensor for glucose detection is analytically modeled. In the proposed model, the glucose concentration is presented as a function of gate voltage. Subsequently, the proposed model is compared with existing experimental data. A good consensus between the model and the experimental data is reported. The simulated data demonstrate that the analytical model can be employed with an electrochemical glucose sensor to predict the behavior of the sensing mechanism in biosensors.
An analytical model for enantioseparation process in capillary electrophoresis
Ranzuglia, G. A.; Manzi, S. J.; Gomez, M. R.; Belardinelli, R. E.; Pereyra, V. D.
2017-12-01
An analytical model to explain the mobilities of enantiomer binary mixture in capillary electrophoresis experiment is proposed. The model consists in a set of kinetic equations describing the evolution of the populations of molecules involved in the enantioseparation process in capillary electrophoresis (CE) is proposed. These equations take into account the asymmetric driven migration of enantiomer molecules, chiral selector and the temporary diastomeric complexes, which are the products of the reversible reaction between the enantiomers and the chiral selector. The solution of these equations gives the spatial and temporal distribution of each species in the capillary, reproducing a typical signal of the electropherogram. The mobility, μ, of each specie is obtained by the position of the maximum (main peak) of their respective distributions. Thereby, the apparent electrophoretic mobility difference, Δμ, as a function of chiral selector concentration, [ C ] , can be measured. The behaviour of Δμ versus [ C ] is compared with the phenomenological model introduced by Wren and Rowe in J. Chromatography 1992, 603, 235. To test the analytical model, a capillary electrophoresis experiment for the enantiomeric separation of the (±)-chlorpheniramine β-cyclodextrin (β-CD) system is used. These data, as well as, other obtained from literature are in closed agreement with those obtained by the model. All these results are also corroborate by kinetic Monte Carlo simulation.
Exploring SMBH assembly with semi-analytic modelling
Ricarte, Angelo; Natarajan, Priyamvada
2018-02-01
We develop a semi-analytic model to explore different prescriptions of supermassive black hole (SMBH) fuelling. This model utilizes a merger-triggered burst mode in concert with two possible implementations of a long-lived steady mode for assembling the mass of the black hole in a galactic nucleus. We improve modelling of the galaxy-halo connection in order to more realistically determine the evolution of a halo's velocity dispersion. We use four model variants to explore a suite of observables: the M•-σ relation, mass functions of both the overall and broad-line quasar population, and luminosity functions as a function of redshift. We find that `downsizing' is a natural consequence of our improved velocity dispersion mappings, and that high-mass SMBHs assemble earlier than low-mass SMBHs. The burst mode of fuelling is sufficient to explain the assembly of SMBHs to z = 2, but an additional steady mode is required to both assemble low-mass SMBHs and reproduce the low-redshift luminosity function. We discuss in detail the trade-offs in matching various observables and the interconnected modelling components that govern them. As a result, we demonstrate the utility as well as the limitations of these semi-analytic techniques.
3D CMM strain-gauge triggering probe error characteristics modeling using fuzzy logic
DEFF Research Database (Denmark)
Achiche, Sofiane; Wozniak, A; Fan, Zhun
2008-01-01
FKBs based on two optimization paradigms are used for the reconstruction of the direction- dependent probe error w. The angles beta and gamma are used as input variables of the FKBs; they describe the spatial direction of probe triggering. The learning algorithm used to generate the FKBs is a real......The error values of CMMs depends on the probing direction; hence its spatial variation is a key part of the probe inaccuracy. This paper presents genetically-generated fuzzy knowledge bases (FKBs) to model the spatial error characteristics of a CMM module-changing probe. Two automatically generated...
3D CMM Strain-Gauge Triggering Probe Error Characteristics Modeling
DEFF Research Database (Denmark)
Achiche, Sofiane; Wozniak, Adam; Fan, Zhun
2008-01-01
FKBs based on two optimization paradigms are used for the reconstruction of the directiondependent probe error w. The angles β and γ are used as input variables of the FKBs; they describe the spatial direction of probe triggering. The learning algorithm used to generate the FKBs is a real/ binary like......The error values of CMMs depends on the probing direction; hence its spatial variation is a key part of the probe inaccuracy. This paper presents genetically-generated fuzzy knowledge bases (FKBs) to model the spatial error characteristics of a CMM module-changing probe. Two automatically generated...
A workflow learning model to improve geovisual analytics utility.
Roth, Robert E; Maceachren, Alan M; McCabe, Craig A
2009-01-01
INTRODUCTION: This paper describes the design and implementation of the G-EX Portal Learn Module, a web-based, geocollaborative application for organizing and distributing digital learning artifacts. G-EX falls into the broader context of geovisual analytics, a new research area with the goal of supporting visually-mediated reasoning about large, multivariate, spatiotemporal information. Because this information is unprecedented in amount and complexity, GIScientists are tasked with the development of new tools and techniques to make sense of it. Our research addresses the challenge of implementing these geovisual analytics tools and techniques in a useful manner. OBJECTIVES: The objective of this paper is to develop and implement a method for improving the utility of geovisual analytics software. The success of software is measured by its usability (i.e., how easy the software is to use?) and utility (i.e., how useful the software is). The usability and utility of software can be improved by refining the software, increasing user knowledge about the software, or both. It is difficult to achieve transparent usability (i.e., software that is immediately usable without training) of geovisual analytics software because of the inherent complexity of the included tools and techniques. In these situations, improving user knowledge about the software through the provision of learning artifacts is as important, if not more so, than iterative refinement of the software itself. Therefore, our approach to improving utility is focused on educating the user. METHODOLOGY: The research reported here was completed in two steps. First, we developed a model for learning about geovisual analytics software. Many existing digital learning models assist only with use of the software to complete a specific task and provide limited assistance with its actual application. To move beyond task-oriented learning about software use, we propose a process-oriented approach to learning based on
A hybrid finite-difference and analytic element groundwater model
Haitjema, Henk M.; Feinstein, Daniel T.; Hunt, Randall J.; Gusyev, Maksym
2010-01-01
Regional finite-difference models tend to have large cell sizes, often on the order of 1–2 km on a side. Although the regional flow patterns in deeper formations may be adequately represented by such a model, the intricate surface water and groundwater interactions in the shallower layers are not. Several stream reaches and nearby wells may occur in a single cell, precluding any meaningful modeling of the surface water and groundwater interactions between the individual features. We propose to replace the upper MODFLOW layer or layers, in which the surface water and groundwater interactions occur, by an analytic element model (GFLOW) that does not employ a model grid; instead, it represents wells and surface waters directly by the use of point-sinks and line-sinks. For many practical cases it suffices to provide GFLOW with the vertical leakage rates calculated in the original coarse MODFLOW model in order to obtain a good representation of surface water and groundwater interactions. However, when the combined transmissivities in the deeper (MODFLOW) layers dominate, the accuracy of the GFLOW solution diminishes. For those cases, an iterative coupling procedure, whereby the leakages between the GFLOW and MODFLOW model are updated, appreciably improves the overall solution, albeit at considerable computational cost. The coupled GFLOW–MODFLOW model is applicable to relatively large areas, in many cases to the entire model domain, thus forming an attractive alternative to local grid refinement or inset models.
Probes of Yukawa unification in supersymmetric SO(10) models
Energy Technology Data Exchange (ETDEWEB)
Westhoff, Susanne
2009-10-23
This work is composed as follows: In Chapter 1, the disposed reader is made familiar with the foundations of flavourphysics and Grand Unification, including group-theoretical aspects of SO(10). In Chapter 2, we introduce a specific supersymmetric GUT model based on SO(10) and designed to probe down-quark-lepton Yukawa unification. Within this framework we explore the effects of large atmospheric neutrino mixing in bottom-strange transitions on the mass difference and CP phase in B{sub s}- anti B{sub s} meson mixing. Chapter 3 is devoted to corrections to Yukawa unification. We derive constraints on Yukawa corrections for light fermions from K- anti K and B{sub d}- anti B {sub d} mixing. As an application we study implications of neutrino mixing effects in CP-violating K and B{sub d} observables on the unitrity triangle. Finally, in Chapter 4, we discuss effects of large tan {beta} in B{yields}(D){tau}{nu} decays with respect to their potential to discover charged Higgs bosons and to discriminate between different GUT models of flavour.
Mathematical Model of Suspension Filtration and Its Analytical Solution
Directory of Open Access Journals (Sweden)
Normahmad Ravshanov
2013-01-01
Full Text Available The work develops advanced mathematical model and computing algorithm to analyze, predict and identify the basic parameters of filter units and their variation ranges. Numerical analytic solution of liquid ionized mixtures filtration was got on their basis. Computing experiments results are presented in graphics form. Calculation results analysis enables to determine the optimum performance of filter units, used for liquid ionized mixtures filtration, food preparation, drug production and water purification. Selection of the most suitable parameters contributes to the improvement of economic and technological efficiency of production and filter units working efficiency.
Shear mechanical properties of the spleen: experiment and analytical modelling.
Nicolle, S; Noguer, L; Palierne, J-F
2012-05-01
This paper aims at providing the first shear mechanical properties of spleen tissue. Rheometric tests on porcine splenic tissues were performed in the linear and nonlinear regime, revealing a weak frequency dependence of the dynamic moduli in linear regime and a distinct strain-hardening effect in nonlinear regime. These behaviours are typical of soft tissues such as kidney and liver, with however a less pronounced strain-hardening for the spleen. An analytical model based on power laws is then proposed to describe the general shear viscoelastic behaviour of the spleen. Copyright © 2012 Elsevier Ltd. All rights reserved.
"Violent Intent Modeling: Incorporating Cultural Knowledge into the Analytical Process
Energy Technology Data Exchange (ETDEWEB)
Sanfilippo, Antonio P.; Nibbs, Faith G.
2007-08-24
While culture has a significant effect on the appropriate interpretation of textual data, the incorporation of cultural considerations into data transformations has not been systematic. Recognizing that the successful prevention of terrorist activities could hinge on the knowledge of the subcultures, Anthropologist and DHS intern Faith Nibbs has been addressing the need to incorporate cultural knowledge into the analytical process. In this Brown Bag she will present how cultural ideology is being used to understand how the rhetoric of group leaders influences the likelihood of their constituents to engage in violent or radicalized behavior, and how violent intent modeling can benefit from understanding that process.
Analytical model of corn cob Pyroprobe-FTIR data
Energy Technology Data Exchange (ETDEWEB)
Feng, Jie; YuHong, Qin [Key Laboratory of Coal Science and Technology, Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China); Green, Alex E.S. [Clean Combustion Technology Laboratory, University of Florida, Gainesville, FL 32611-6550 (United States)
2006-05-15
Pyrolysis of various forms of biomass could convert this primary energy source into valuable liquid or gaseous fuels or chemicals. In this study a CDS 2000 Pyroprobe, with a Bio-Rad FTS165 FTIR detector are used to measure yields of 3 products and 7 families of products from corn cobs pyrolysis at temperatures up to 900{sup o}C using a wide range of heating rates. An analytical semi-empirical model is then used to approximately represent these results using a relatively small number of parameters. The compact representation can be used in applications to conveniently extrapolate and interpolate these results to other temperatures and heating rates. (author)
Analytic models of CMOS logic in various regimes
Directory of Open Access Journals (Sweden)
Dokić Branko
2014-01-01
Full Text Available In this paper, comparative analytic models of static and dynamic characteristics of CMOS digital circuits in strong, weak and mixed inversion regime have been described. Term mixed inversion is defined for the first time. The paper shows that there is an analogy in behavior and functional dependencies of parameters in all three CMOS regimes. Comparative characteristics of power consumption and speed in static regimes are given. Dependency of threshold voltage and logic delay time on temperature has been analyzed. Dynamic model with constant current is proposed. It is shown that digital circuits with dynamic threshold voltage of MOS transistor (DT-CMOS have better logic delay characteristics. The analysis is based on simplified current-voltage MOS transistor models in strong and weak inversion regimes, as well as PSPICE software using 180 nm technology parameters.
Analytic model of Applied-B ion diode impedance behavior
International Nuclear Information System (INIS)
Miller, P.A.; Mendel, C.W. Jr.
1987-01-01
An empirical analysis of impedance data from Applied-B ion diodes used in seven inertial confinement fusion research experiments was published recently. The diodes all operated with impedance values well below the Child's-law value. The analysis uncovered an unusual unifying relationship among data from the different experiments. The analysis suggested that closure of the anode-cathode gap by electrode plasma was not a dominant factor in the experiments, but was not able to elaborate the underlying physics. Here we present a new analytic model of Applied-B ion diodes coupled to accelerators. A critical feature of the diode model is based on magnetic insulation theory. The model successfully describes impedance behavior of these diodes and supports stimulating new viewpoints of the physics of Applied-B ion diode operation
Challenges in the development of analytical soil compaction models
DEFF Research Database (Denmark)
Keller, Thomas; Lamandé, Mathieu
2010-01-01
Soil compaction can cause a number of environmental and agronomic problems (e.g. flooding, erosion, leaching of agrochemicals to recipient waters, emission of greenhouse gases to the atmosphere, crop yield losses), resulting in significant economic damage to society and agriculture. Strategies...... and recommendations for the prevention of soil compaction often rely on simulation models. This paper highlights some issues that need further consideration in order to improve soil compaction modelling, with the focus on analytical models. We discuss the different issues based on comparisons between experimental...... to stress propagation, an anomaly that needs further attention. We found large differences between soil stress-strain behaviour obtained from in situ measurements during wheeling experiments and those measured on cylindrical soil samples in standard laboratory tests. We concluded that the main reason...
Analytical Model of Symmetric Halo Doped DG-Tunnel FET
Directory of Open Access Journals (Sweden)
S. Nagarajan
2015-11-01
Full Text Available Two-dimensional analytical model of symmetric halo doped double gate tunnel field effect transistor has been presented in this work. This model is developed based on the 2-D Poisson’s equation. Some important parameters such that surface potential, vertical and lateral electric field, electric field intensity and band energy have been modelled. The doping concentration and length of halo regions are varied and dependency of various parameters is studied. The halo doping is imparted to improve the ON current and to reduce the intrinsic ambipolarity of the device. Hence we can achieve improved ION/IOFF ratio. The scaling property of halo doped structure is analyzed with various dielectric constants.
Simplified analytical model for radionuclide transport simulation in the geosphere
International Nuclear Information System (INIS)
Hiromoto, G.
1996-01-01
In order to evaluate postclosure off-site doses from a low-level radioactive waste disposal facilities, an integrated safety assessment methodology has being developed at Instituto de Pesquisas Energeticas e Nucleares. The source-term modelling approach adopted in this system is described and the results obtained in the IAEA NSARS 'The Safety Assessment of Near-Surface Radioactive Waste Disposal Facilities' programme for model intercomparison studies are presented. The radionuclides released from the waste are calculated using a simple first order kinetics model, and the transport, through porous media below the waste is determined by using an analytical solution of the mass transport equation. The methodology and the results obtained in this work are compared with those reported by others participants of the NSARS programme. (author). 4 refs., 4 figs
Integer Representations towards Efficient Counting in the Bit Probe Model
DEFF Research Database (Denmark)
Brodal, Gerth Stølting; Greve, Mark; Pandey, Vineet
2011-01-01
Abstract We consider the problem of representing numbers in close to optimal space and supporting increment, decrement, addition and subtraction operations efficiently. We study the problem in the bit probe model and analyse the number of bits read and written to perform the operations, both...... in the worst-case and in the average-case. A counter is space-optimal if it represents any number in the range [0,...,2 n − 1] using exactly n bits. We provide a space-optimal counter which supports increment and decrement operations by reading at most n − 1 bits and writing at most 3 bits in the worst......-case. To the best of our knowledge, this is the first such representation which supports these operations by always reading strictly less than n bits. For redundant counters where we only need to represent numbers in the range [0,...,L] for some integer L bits, we define the efficiency...
Validated Analytical Model of a Pressure Compensation Drip Irrigation Emitter
Shamshery, Pulkit; Wang, Ruo-Qian; Taylor, Katherine; Tran, Davis; Winter, Amos
2015-11-01
This work is focused on analytically characterizing the behavior of pressure-compensating drip emitters in order to design low-cost, low-power irrigation solutions appropriate for off-grid communities in developing countries. There are 2.5 billion small acreage farmers worldwide who rely solely on their land for sustenance. Drip, compared to flood, irrigation leads to up to 70% reduction in water consumption while increasing yields by 90% - important in countries like India which are quickly running out of water. To design a low-power drip system, there is a need to decrease the pumping pressure requirement at the emitters, as pumping power is the product of pressure and flow rate. To efficiently design such an emitter, the relationship between the fluid-structure interactions that occur in an emitter need to be understood. In this study, a 2D analytical model that captures the behavior of a common drip emitter was developed and validated through experiments. The effects of independently changing the channel depth, channel width, channel length and land height on the performance were studied. The model and the key parametric insights presented have the potential to be optimized in order to guide the design of low-pressure, clog-resistant, pressure-compensating emitters.
Analytic Models of Brown Dwarfs and the Substellar Mass Limit
Directory of Open Access Journals (Sweden)
Sayantan Auddy
2016-01-01
Full Text Available We present the analytic theory of brown dwarf evolution and the lower mass limit of the hydrogen burning main-sequence stars and introduce some modifications to the existing models. We give an exact expression for the pressure of an ideal nonrelativistic Fermi gas at a finite temperature, therefore allowing for nonzero values of the degeneracy parameter. We review the derivation of surface luminosity using an entropy matching condition and the first-order phase transition between the molecular hydrogen in the outer envelope and the partially ionized hydrogen in the inner region. We also discuss the results of modern simulations of the plasma phase transition, which illustrate the uncertainties in determining its critical temperature. Based on the existing models and with some simple modification, we find the maximum mass for a brown dwarf to be in the range 0.064M⊙–0.087M⊙. An analytic formula for the luminosity evolution allows us to estimate the time period of the nonsteady state (i.e., non-main-sequence nuclear burning for substellar objects. We also calculate the evolution of very low mass stars. We estimate that ≃11% of stars take longer than 107 yr to reach the main sequence, and ≃5% of stars take longer than 108 yr.
Characterization of uniform scanning proton beams with analytical models
Demez, Nebi
Tissue equivalent phantoms have an important place in radiation therapy planning and delivery. They have been manufactured for use in conventional radiotherapy. Their tissue equivalency for proton beams is currently in active investigation. The Bragg-Kleeman rule was used to calculate water equivalent thickness (WET) for available tissue equivalent phantoms from CIRS (Norfolk, VA, USA). WET's of those phantoms were also measured using proton beams at Hampton University Proton Therapy Institute (HUPTI). WET measurements and calculations are in good agreement within ˜1% accuracy except for high Z phantoms. Proton beams were also characterized with an analytical proton dose calculation model, Proton Loss Model (PLM) [26], to investigate protons interactions in water and those phantoms. Depth-dose and lateral dose profiles of protons in water and in those phantoms were calculated, measured, and compared. Water Equivalent Spreadness (WES) was also investigated for those phantoms using the formula for scattering power ratio. Because WES is independent of incident energy of protons, it is possible to estimate spreadness of protons in different media by just knowing WES. Measurements are usually taken for configuration of the treatment planning system (TPS). This study attempted to achieve commissioning data for uniform scanning proton planning with analytical methods, PLM, which have been verified with published measurements and Monte Carlo calculations. Depth doses and lateral profiles calculated by PLM were compared with measurements via the gamma analysis method. While gamma analysis shows that depth doses are in >90% agreement with measured depth doses, the agreement falls to <80% for some lateral profiles. PLM data were imported into the TPS (PLM-TPS). PLM-TPS was tested with different patient cases. The PLM-TPS treatment plans for 5 prostate cases show acceptable agreement. The Planning Treatment Volume (PTV) coverage was 100 % with PLM-TPS except for one case in
Analysis of Power Switching Losses Accounting Probe Modeling
Ammous , Kaiçar; Morel , Hervé; Ammous , Anis
2010-01-01
International audience; This paper focuses on the errors affecting the estimation of power switching losses in power semiconductor devices based on integration of the voltage by current product. It is shown that the measured waveforms are not simply delayed by the probes, but some overshoots and distortions are due to the probes, which may not easily be corrected. These effects are the source of errors, particularly in fast transients. This paper shows analyses of simulation and measurements,...
Analytical and numerical performance models of a Heisenberg Vortex Tube
Bunge, C. D.; Cavender, K. A.; Matveev, K. I.; Leachman, J. W.
2017-12-01
Analytical and numerical investigations of a Heisenberg Vortex Tube (HVT) are performed to estimate the cooling potential with cryogenic hydrogen. The Ranque-Hilsch Vortex Tube (RHVT) is a device that tangentially injects a compressed fluid stream into a cylindrical geometry to promote enthalpy streaming and temperature separation between inner and outer flows. The HVT is the result of lining the inside of a RHVT with a hydrogen catalyst. This is the first concept to utilize the endothermic heat of para-orthohydrogen conversion to aid primary cooling. A review of 1st order vortex tube models available in the literature is presented and adapted to accommodate cryogenic hydrogen properties. These first order model predictions are compared with 2-D axisymmetric Computational Fluid Dynamics (CFD) simulations.
Quantum quench dynamics in analytically solvable one-dimensional models
Iucci, Anibal; Cazalilla, Miguel A.; Giamarchi, Thierry
2008-03-01
In connection with experiments in cold atomic systems, we consider the non-equilibrium dynamics of some analytically solvable one-dimensional systems which undergo a quantum quench. In this quench one or several of the parameters of the Hamiltonian of an interacting quantum system are changed over a very short time scale. In particular, we concentrate on the Luttinger model and the sine-Gordon model in the Luther-Emery point. For the latter, we show that the order parameter and the two-point correlation function relax in the long time limit to the values determined by a generalized Gibbs ensemble first discussed by J. T. Jaynes [Phys. Rev. 106, 620 (1957); 108, 171 (1957)], and recently conjectured by M. Rigol et.al. [Phys. Rev. Lett. 98, 050405 (2007)] to apply to the non-equilibrium dynamics of integrable systems.
Analytical modeling of mid-infrared silicon Raman lasers
Ma, J.; Fathpour, S.
2012-01-01
Silicon photonics has significantly matured in the near-infrared (telecommunication) wavelength range with several commercial products already in the market. More recently, the technology has been extended into the mid-infrared (mid- IR) regime with potential applications in biochemical sensing, tissue photoablation, environmental monitoring and freespace communications. The key advantage of silicon in the mid-IR, as compared with near-IR, is the absence of twophoton absorption (TPA) and free-carrier absorption (FCA). The absence of these nonlinear losses would potentially lead to high-performance nonlinear devices based on Raman and Kerr effects. Also, with the absence of TPA and FCA, the coupled-wave equations that are usually numerically solved to model these nonlinear devices lend themselves to analytical solutions in the mid-IR. In this paper, an analytical model for mid-IR silicon Raman lasers is developed. The validity of the model is confirmed by comparing it with numerical solutions of the coupled-wave equations. The developed model can be used as a versatile and efficient tool for analysis, design and optimization of mid-IR silicon Raman lasers, or to find good initial guesses for numerical methods. The effects of cavity parameters, such as cavity length and facet reflectivities, on the lasing threshold and input-output characteristics of the Raman laser are studied. For instance, for a propagation loss of 0.5 dB/cm, conversion efficiencies as high as 56% is predicted. The predicted optimum cavity (waveguide) length at 2.0 dB/cm propagation loss is { 3.4 mm. The results of this study predict strong prospects for mid-IR silicon Raman lasers for the mentioned applications.
Progressive Learning of Topic Modeling Parameters: A Visual Analytics Framework.
El-Assady, Mennatallah; Sevastjanova, Rita; Sperrle, Fabian; Keim, Daniel; Collins, Christopher
2018-01-01
Topic modeling algorithms are widely used to analyze the thematic composition of text corpora but remain difficult to interpret and adjust. Addressing these limitations, we present a modular visual analytics framework, tackling the understandability and adaptability of topic models through a user-driven reinforcement learning process which does not require a deep understanding of the underlying topic modeling algorithms. Given a document corpus, our approach initializes two algorithm configurations based on a parameter space analysis that enhances document separability. We abstract the model complexity in an interactive visual workspace for exploring the automatic matching results of two models, investigating topic summaries, analyzing parameter distributions, and reviewing documents. The main contribution of our work is an iterative decision-making technique in which users provide a document-based relevance feedback that allows the framework to converge to a user-endorsed topic distribution. We also report feedback from a two-stage study which shows that our technique results in topic model quality improvements on two independent measures.
A hidden analytic structure of the Rabi model
Energy Technology Data Exchange (ETDEWEB)
Moroz, Alexander, E-mail: wavescattering@yahoo.com
2014-01-15
The Rabi model describes the simplest interaction between a cavity mode with a frequency ω{sub c} and a two-level system with a resonance frequency ω{sub 0}. It is shown here that the spectrum of the Rabi model coincides with the support of the discrete Stieltjes integral measure in the orthogonality relations of recently introduced orthogonal polynomials. The exactly solvable limit of the Rabi model corresponding to Δ=ω{sub 0}/(2ω{sub c})=0, which describes a displaced harmonic oscillator, is characterized by the discrete Charlier polynomials in normalized energy ϵ, which are orthogonal on an equidistant lattice. A non-zero value of Δ leads to non-classical discrete orthogonal polynomials ϕ{sub k}(ϵ) and induces a deformation of the underlying equidistant lattice. The results provide a basis for a novel analytic method of solving the Rabi model. The number of ca. 1350 calculable energy levels per parity subspace obtained in double precision (cca 16 digits) by an elementary stepping algorithm is up to two orders of magnitude higher than is possible to obtain by Braak’s solution. Any first n eigenvalues of the Rabi model arranged in increasing order can be determined as zeros of ϕ{sub N}(ϵ) of at least the degree N=n+n{sub t}. The value of n{sub t}>0, which is slowly increasing with n, depends on the required precision. For instance, n{sub t}≃26 for n=1000 and dimensionless interaction constant κ=0.2, if double precision is required. Given that the sequence of the lth zeros x{sub nl}’s of ϕ{sub n}(ϵ)’s defines a monotonically decreasing discrete flow with increasing n, the Rabi model is indistinguishable from an algebraically solvable model in any finite precision. Although we can rigorously prove our results only for dimensionless interaction constant κ<1, numerics and exactly solvable example suggest that the main conclusions remain to be valid also for κ≥1. -- Highlights: •A significantly simplified analytic solution of the Rabi model
Exploring Higher Education Governance: Analytical Models and Heuristic Frameworks
Directory of Open Access Journals (Sweden)
Burhan FINDIKLI
2017-08-01
Full Text Available Governance in higher education, both at institutional and systemic levels, has experienced substantial changes within recent decades because of a range of world-historical processes such as massification, growth, globalization, marketization, public sector reforms, and the emergence of knowledge economy and society. These developments have made governance arrangements and decision-making processes in higher education more complex and multidimensional more than ever and forced scholars to build new analytical and heuristic tools and strategies to grasp the intricacy and diversity of higher education governance dynamics. This article provides a systematic discussion of how and through which tools prominent scholars of higher education have analyzed governance in this sector by examining certain heuristic frameworks and analytical models. Additionally, the article shows how social scientific analysis of governance in higher education has proceeded in a cumulative way with certain revisions and syntheses rather than radical conceptual and theoretical ruptures from Burton R. Clark’s seminal work to the present, revealing conceptual and empirical junctures between them.
Analytical model of diffuse reflectance spectrum of skin tissue
Energy Technology Data Exchange (ETDEWEB)
Lisenko, S A; Kugeiko, M M; Firago, V A [Belarusian State University, Minsk (Belarus); Sobchuk, A N [B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Minsk (Belarus)
2014-01-31
We have derived simple analytical expressions that enable highly accurate calculation of diffusely reflected light signals of skin in the spectral range from 450 to 800 nm at a distance from the region of delivery of exciting radiation. The expressions, taking into account the dependence of the detected signals on the refractive index, transport scattering coefficient, absorption coefficient and anisotropy factor of the medium, have been obtained in the approximation of a two-layer medium model (epidermis and dermis) for the same parameters of light scattering but different absorption coefficients of layers. Numerical experiments on the retrieval of the skin biophysical parameters from the diffuse reflectance spectra simulated by the Monte Carlo method show that commercially available fibre-optic spectrophotometers with a fixed distance between the radiation source and detector can reliably determine the concentration of bilirubin, oxy- and deoxyhaemoglobin in the dermis tissues and the tissue structure parameter characterising the size of its effective scatterers. We present the examples of quantitative analysis of the experimental data, confirming the correctness of estimates of biophysical parameters of skin using the obtained analytical expressions. (biophotonics)
Finite element and analytical models for twisted and coiled actuator
Tang, Xintian; Liu, Yingxiang; Li, Kai; Chen, Weishan; Zhao, Jianguo
2018-01-01
Twisted and coiled actuator (TCA) is a class of recently discovered artificial muscle, which is usually made by twisting and coiling polymer fibers into spring-like structures. It has been widely studied since discovery due to its impressive output characteristics and bright prospects. However, its mathematical models describing the actuation in response to the temperature are still not fully developed. It is known that the large tensile stroke is resulted from the untwisting of the twisted fiber when heated. Thus, the recovered torque during untwisting is a key parameter in the mathematical model. This paper presents a simplified model for the recovered torque of TCA. Finite element method is used for evaluating the thermal stress of the twisted fiber. Based on the results of the finite element analyses, the constitutive equations of twisted fibers are simplified to develop an analytic model of the recovered torque. Finally, the model of the recovered torque is used to predict the deformation of TCA under varying temperatures and validated against experimental results. This work will enhance our understanding of the deformation mechanism of TCAs, which will pave the way for the closed-loop position control.
Model choice considerations and information integration using analytical hierarchy process
Energy Technology Data Exchange (ETDEWEB)
Langenbrunner, James R [Los Alamos National Laboratory; Hemez, Francois M [Los Alamos National Laboratory; Booker, Jane M [BOOKER SCIENTIFIC; Ross, Timothy J. [UNM
2010-10-15
Using the theory of information-gap for decision-making under severe uncertainty, it has been shown that model output compared to experimental data contains irrevocable trade-offs between fidelity-to-data, robustness-to-uncertainty and confidence-in-prediction. We illustrate a strategy for information integration by gathering and aggregating all available data, knowledge, theory, experience, similar applications. Such integration of information becomes important when the physics is difficult to model, when observational data are sparse or difficult to measure, or both. To aggregate the available information, we take an inference perspective. Models are not rejected, nor wasted, but can be integrated into a final result. We show an example of information integration using Saaty's Analytic Hierarchy Process (AHP), integrating theory, simulation output and experimental data. We used expert elicitation to determine weights for two models and two experimental data sets, by forming pair-wise comparisons between model output and experimental data. In this way we transform epistemic and/or statistical strength from one field of study into another branch of physical application. The price to pay for utilizing all available knowledge is that inferences drawn for the integrated information must be accounted for and the costs can be considerable. Focusing on inferences and inference uncertainty (IU) is one way to understand complex information.
Analytical model of stemwood growth in relation to nitrogen supply
Energy Technology Data Exchange (ETDEWEB)
Dewar, R. C.; McMurtrie, R. E. [New South Wales Univ., Sydney, NSW (Australia)
1996-01-01
A process-based model of tree stand growth that simulates the effect of nitrogen supply on forest productivity has been recently combined with a soil-carbon-nitrogen model. The combined model, called G`DAY has been used to examine the long-term response of unmanaged forest ecosystems to increasing CO{sub 2} concentration. In this study an attempt was made to derive a simplified, analytically tractable version of the plant production part of G`DAY, and use it to gain insight into the general relationship between stemwood growth and nitrogen supply in managed forests. The particular focus of the study was on using the model to predict how the maximum annual stemwood growth and optimal rotation length can be expected to vary in response to changes in nitrogen supply from net mineralization, fertilizer addition, fixation and atmospheric deposition. Overall, the model was considered to be a useful tool in examining the effects of changes in climate and nutrient supply on sustainable forest productivity. 20 refs., 2 tabs., 5 figs.
Simulation Model for Correction and Modeling of Probe Head Errors in Five-Axis Coordinate Systems
Directory of Open Access Journals (Sweden)
Adam Gąska
2016-05-01
Full Text Available Simulative methods are nowadays frequently used in metrology for the simulation of measurement uncertainty and the prediction of errors that may occur during measurements. In coordinate metrology, such methods are primarily used with the typical three-axis Coordinate Measuring Machines (CMMs, and lately, also with mobile measuring systems. However, no similar simulative models have been developed for five-axis systems in spite of their growing popularity in recent years. This paper presents the numerical model of probe head errors for probe heads that are used in five-axis coordinate systems. The model is based on measurements of material standards (standard ring and the use of the Monte Carlo method combined with select interpolation methods. The developed model may be used in conjunction with one of the known models of CMM kinematic errors to form a virtual model of a five-axis coordinate system. In addition, the developed methodology allows for the correction of identified probe head errors, thus improving measurement accuracy. Subsequent verification tests prove the correct functioning of the presented model.
On The Sfr-M* Main Sequence Archetypal Star-Formation History And Analytical Models
Ciesla, Laure; Elbaz, David; Fensch, Jeremy
2017-06-01
From the evolution of the main sequence we can build the star formation history (SFH) of MS galaxies, assuming that they follow this relation all their life. We show that this SFH is not only a function of cosmic time but also involve the seed mass of the galaxy. We discuss the implications of this MS SFH on the stellar mass growth, and the entry in the passive region of the UVJ diagram, while the galaxy is still forming stars. We test the ability of different analytical SFH forms found in the literature to probe the SFR of all type of galaxies. Using a sample of GOODS-South galaxies, we show that these SFHs artificially enhance or create a gradient of age, parallel to the MS. A simple model of a MS galaxy, such as those expected from compaction or variation in gas accretion, undergoing some fluctuations provide does not predict such a gradient, that we show is due to SFH assumptions. We propose an improved analytical form, taking into account a flexibility in the recent SFH that we calibrate as a diagnostic to identify rapidly quenched galaxies from large photometric survey.
Design of homogeneous trench-assisted multi-core fibers based on analytical model
DEFF Research Database (Denmark)
Ye, Feihong; Tu, Jiajing; Saitoh, Kunimasa
2016-01-01
We present a design method of homogeneous trench-assisted multicore fibers (TA-MCFs) based on an analytical model utilizing an analytical expression for the mode coupling coefficient between two adjacent cores. The analytical model can also be used for crosstalk (XT) properties analysis, such as ...
Analytical modeling of wet compression of gas turbine systems
International Nuclear Information System (INIS)
Kim, Kyoung Hoon; Ko, Hyung-Jong; Perez-Blanco, Horacio
2011-01-01
Evaporative gas turbine cycles (EvGT) are of importance to the power generation industry because of the potential of enhanced cycle efficiencies with moderate incremental cost. Humidification of the working fluid to result in evaporative cooling during compression is a key operation in these cycles. Previous simulations of this operation were carried out via numerical integration. The present work is aimed at modeling the wet-compression process with approximate analytical solutions instead. A thermodynamic analysis of the simultaneous heat and mass transfer processes that occur during evaporation is presented. The transient behavior of important variables in wet compression such as droplet diameter, droplet mass, gas and droplet temperature, and evaporation rate is investigated. The effects of system parameters on variables such as droplet evaporation time, compressor outlet temperature and input work are also considered. Results from this work exhibit good agreement with those of previous numerical work.
Analytical Modelling Of Milling For Tool Design And Selection
Fontaine, M.; Devillez, A.; Dudzinski, D.
2007-05-01
This paper presents an efficient analytical model which allows to simulate a large panel of milling operations. A geometrical description of common end mills and of their engagement in the workpiece material is proposed. The internal radius of the rounded part of the tool envelope is used to define the considered type of mill. The cutting edge position is described for a constant lead helix and for a constant local helix angle. A thermomechanical approach of oblique cutting is applied to predict forces acting on the tool and these results are compared with experimental data obtained from milling tests on a 42CrMo4 steel for three classical types of mills. The influence of some tool's geometrical parameters on predicted cutting forces is presented in order to propose optimisation criteria for design and selection of cutting tools.
Analytical Modelling Of Milling For Tool Design And Selection
International Nuclear Information System (INIS)
Fontaine, M.; Devillez, A.; Dudzinski, D.
2007-01-01
This paper presents an efficient analytical model which allows to simulate a large panel of milling operations. A geometrical description of common end mills and of their engagement in the workpiece material is proposed. The internal radius of the rounded part of the tool envelope is used to define the considered type of mill. The cutting edge position is described for a constant lead helix and for a constant local helix angle. A thermomechanical approach of oblique cutting is applied to predict forces acting on the tool and these results are compared with experimental data obtained from milling tests on a 42CrMo4 steel for three classical types of mills. The influence of some tool's geometrical parameters on predicted cutting forces is presented in order to propose optimisation criteria for design and selection of cutting tools
An Analytical Model of Joule Heating in Piezoresistive Microcantilevers
Directory of Open Access Journals (Sweden)
Chongdu Cho
2010-11-01
Full Text Available The present study investigates Joule heating in piezoresistive microcantilever sensors. Joule heating and thermal deflections are a major source of noise in such sensors. This work uses analytical and numerical techniques to characterise the Joule heating in 4-layer piezoresistive microcantilevers made of silicon and silicon dioxide substrates but with the same U-shaped silicon piezoresistor. A theoretical model for predicting the temperature generated due to Joule heating is developed. The commercial finite element software ANSYS Multiphysics was used to study the effect of electrical potential on temperature and deflection produced in the cantilevers. The effect of piezoresistor width on Joule heating is also studied. Results show that Joule heating strongly depends on the applied potential and width of piezoresistor and that a silicon substrate cantilever has better thermal characteristics than a silicon dioxide cantilever.
A hidden analytic structure of the Rabi model
Moroz, Alexander
2014-01-01
The Rabi model describes the simplest interaction between a cavity mode with a frequency ωc and a two-level system with a resonance frequency ω0. It is shown here that the spectrum of the Rabi model coincides with the support of the discrete Stieltjes integral measure in the orthogonality relations of recently introduced orthogonal polynomials. The exactly solvable limit of the Rabi model corresponding to Δ=ω0/(2ωc)=0, which describes a displaced harmonic oscillator, is characterized by the discrete Charlier polynomials in normalized energy ɛ, which are orthogonal on an equidistant lattice. A non-zero value of Δ leads to non-classical discrete orthogonal polynomials ϕk(ɛ) and induces a deformation of the underlying equidistant lattice. The results provide a basis for a novel analytic method of solving the Rabi model. The number of ca. 1350 calculable energy levels per parity subspace obtained in double precision (cca 16 digits) by an elementary stepping algorithm is up to two orders of magnitude higher than is possible to obtain by Braak's solution. Any first n eigenvalues of the Rabi model arranged in increasing order can be determined as zeros of ϕN(ɛ) of at least the degree N=n+nt. The value of nt>0, which is slowly increasing with n, depends on the required precision. For instance, nt≃26 for n=1000 and dimensionless interaction constant κ=0.2, if double precision is required. Given that the sequence of the lth zeros x's of ϕn(ɛ)'s defines a monotonically decreasing discrete flow with increasing n, the Rabi model is indistinguishable from an algebraically solvable model in any finite precision. Although we can rigorously prove our results only for dimensionless interaction constant κ<1, numerics and exactly solvable example suggest that the main conclusions remain to be valid also for κ≥1.
Probing physics beyond the standard model in diatomic molecules
International Nuclear Information System (INIS)
Denis, M.
2017-01-01
Nowadays, the incompleteness of the Standard Model of particles (SM) is largely acknowledged. One of its most obvious shortcomings is the lack of explanation for the huge surplus of matter over antimatter in the universe, the so-called baryon asymmetry of the universe. New CP (charge conjugation and spatial parity) violations absent in the SM are assumed to be responsible for this asymmetry. Such a violation could be observed, in ordinary matter through a set of interactions violating both parity and time-reversal symmetries (P, T -odd) among which the preponderant ones are the electron Electric Dipole Moment (eEDM), the electron-nucleon scalar-pseudoscalar (enSPS) and the nuclear magnetic quadrupole moment (nMQM) interactions. Hence, an experimental evidence of a non-zero P, T -odd interaction constant would be a probe of this New Physics beyond the Standard Model. The calculation of the corresponding molecular parameters is performed by making use of an elaborate four-component relativistic configuration interaction approach in polar diatomic molecules containing an actinide, that are particularly adequate systems for eEDM experiments, such as ThO that allowed for assigning the most constraining upper bound on the eEDM and ThF + that will be used in a forthcoming experiment. Those results will be of crucial importance in the interpretation of the measurements since the fundamental constants can only be evaluated if one combines both experimental energy shift measurements and theoretical molecular parameters. This manuscript proceeds as follows, after an introduction to the general background of the search of CP-violations and its consequences for the understanding of the Universe (Chapter 1), a presentation of the underlying theory of the evidence of such violation in ordinary matter, namely the P, T -odd sources of the Electric Dipole Moment of a many-electron system, as well as the relevant molecular parameters is given in Chapter 2. A similar introduction to
A simulation-based analytic model of radio galaxies
Hardcastle, M. J.
2018-04-01
I derive and discuss a simple semi-analytical model of the evolution of powerful radio galaxies which is not based on assumptions of self-similar growth, but rather implements some insights about the dynamics and energetics of these systems derived from numerical simulations, and can be applied to arbitrary pressure/density profiles of the host environment. The model can qualitatively and quantitatively reproduce the source dynamics and synchrotron light curves derived from numerical modelling. Approximate corrections for radiative and adiabatic losses allow it to predict the evolution of radio spectral index and of inverse-Compton emission both for active and `remnant' sources after the jet has turned off. Code to implement the model is publicly available. Using a standard model with a light relativistic (electron-positron) jet, subequipartition magnetic fields, and a range of realistic group/cluster environments, I simulate populations of sources and show that the model can reproduce the range of properties of powerful radio sources as well as observed trends in the relationship between jet power and radio luminosity, and predicts their dependence on redshift and environment. I show that the distribution of source lifetimes has a significant effect on both the source length distribution and the fraction of remnant sources expected in observations, and so can in principle be constrained by observations. The remnant fraction is expected to be low even at low redshift and low observing frequency due to the rapid luminosity evolution of remnants, and to tend rapidly to zero at high redshift due to inverse-Compton losses.
Galactic conformity measured in semi-analytic models
Lacerna, I.; Contreras, S.; González, R. E.; Padilla, N.; Gonzalez-Perez, V.
2018-03-01
We study the correlation between the specific star formation rate of central galaxies and neighbour galaxies, also known as `galactic conformity', out to 20 h^{-1} {Mpc} using three semi-analytic models (SAMs, one from L-GALAXIES and other two from GALFORM). The aim is to establish whether SAMs are able to show galactic conformity using different models and selection criteria. In all the models, when the selection of primary galaxies is based on an isolation criterion in real space, the mean fraction of quenched (Q) galaxies around Q primary galaxies is higher than that around star-forming primary galaxies of the same stellar mass. The overall signal of conformity decreases when we remove satellites selected as primary galaxies, but the effect is much stronger in GALFORM models compared with the L-GALAXIES model. We find this difference is partially explained by the fact that in GALFORM once a galaxy becomes a satellite remains as such, whereas satellites can become centrals at a later time in L-GALAXIES. The signal of conformity decreases down to 60 per cent in the L-GALAXIES model after removing central galaxies that were ejected from their host halo in the past. Galactic conformity is also influenced by primary galaxies at fixed stellar mass that reside in dark matter haloes of different masses. Finally, we explore a proxy of conformity between distinct haloes. In this case, the conformity is weak beyond ˜3 h^{-1} {Mpc} (conformity is directly related with a long-range effect.
Analytical modelling for ultrasonic surface mechanical attrition treatment
Directory of Open Access Journals (Sweden)
Guan-Rong Huang
2015-07-01
Full Text Available The grain refinement, gradient structure, fatigue limit, hardness, and tensile strength of metallic materials can be effectively enhanced by ultrasonic surface mechanical attrition treatment (SMAT, however, never before has SMAT been treated with rigorous analytical modelling such as the connection among the input energy and power and resultant temperature of metallic materials subjected to SMAT. Therefore, a systematic SMAT model is actually needed. In this article, we have calculated the averaged speed, duration time of a cycle, kinetic energy and kinetic energy loss of flying balls in SMAT for structural metallic materials. The connection among the quantities such as the frequency and amplitude of attrition ultrasonic vibration motor, the diameter, mass and density of balls, the sample mass, and the height of chamber have been considered and modelled in details. And we have introduced the one-dimensional heat equation with heat source within uniform-distributed depth in estimating the temperature distribution and heat energy of sample. In this approach, there exists a condition for the frequency of flying balls reaching a steady speed. With these known quantities, we can estimate the strain rate, hardness, and grain size of sample.
Applying fuzzy analytic network process in quality function deployment model
Directory of Open Access Journals (Sweden)
Mohammad Ali Afsharkazemi
2012-08-01
Full Text Available In this paper, we propose an empirical study of QFD implementation when fuzzy numbers are used to handle the uncertainty associated with different components of the proposed model. We implement fuzzy analytical network to find the relative importance of various criteria and using fuzzy numbers we calculate the relative importance of these factors. The proposed model of this paper uses fuzzy matrix and house of quality to study the products development in QFD and also the second phase i.e. part deployment. In most researches, the primary objective is only on CRs to implement the quality function deployment and some other criteria such as production costs, manufacturing costs etc were disregarded. The results of using fuzzy analysis network process based on the QFD model in Daroupat packaging company to develop PVDC show that the most important indexes are being waterproof, resistant pill packages, and production cost. In addition, the PVDC coating is the most important index in terms of company experts’ point of view.
Green Transport Balanced Scorecard Model with Analytic Network Process Support
Directory of Open Access Journals (Sweden)
David Staš
2015-11-01
Full Text Available In recent decades, the performance of economic and non-economic activities has required them to be friendly with the environment. Transport is one of the areas having considerable potential within the scope. The main assumption to achieve ambitious green goals is an effective green transport evaluation system. However, these systems are researched from the industrial company and supply chain perspective only sporadically. The aim of the paper is to design a conceptual framework for creating the Green Transport (GT Balanced Scorecard (BSC models from the viewpoint of industrial companies and supply chains using an appropriate multi-criteria decision making method. The models should allow green transport performance evaluation and support of an effective implementation of green transport strategies. Since performance measures used in Balanced Scorecard models are interdependent, the Analytic Network Process (ANP was used as the appropriate multi-criteria decision making method. The verification of the designed conceptual framework was performed on a real supply chain of the European automotive industry.
Probing cellular mechanoadaptation using cell-substrate de-adhesion dynamics: experiments and model.
S S, Soumya; Sthanam, Lakshmi Kavitha; Padinhateeri, Ranjith; Inamdar, Mandar M; Sen, Shamik
2014-01-01
Physical properties of the extracellular matrix (ECM) are known to regulate cellular processes ranging from spreading to differentiation, with alterations in cell phenotype closely associated with changes in physical properties of cells themselves. When plated on substrates of varying stiffness, fibroblasts have been shown to exhibit stiffness matching property, wherein cell cortical stiffness increases in proportion to substrate stiffness up to 5 kPa, and subsequently saturates. Similar mechanoadaptation responses have also been observed in other cell types. Trypsin de-adhesion represents a simple experimental framework for probing the contractile mechanics of adherent cells, with de-adhesion timescales shown to scale inversely with cortical stiffness values. In this study, we combine experiments and computation in deciphering the influence of substrate properties in regulating de-adhesion dynamics of adherent cells. We first show that NIH 3T3 fibroblasts cultured on collagen-coated polyacrylamide hydrogels de-adhere faster on stiffer substrates. Using a simple computational model, we qualitatively show how substrate stiffness and cell-substrate bond breakage rate collectively influence de-adhesion timescales, and also obtain analytical expressions of de-adhesion timescales in certain regimes of the parameter space. Finally, by comparing stiffness-dependent experimental and computational de-adhesion responses, we show that faster de-adhesion on stiffer substrates arises due to force-dependent breakage of cell-matrix adhesions. In addition to illustrating the utility of employing trypsin de-adhesion as a biophysical tool for probing mechanoadaptation, our computational results highlight the collective interplay of substrate properties and bond breakage rate in setting de-adhesion timescales.
Enabling analytical and Modeling Tools for Enhanced Disease Surveillance
Energy Technology Data Exchange (ETDEWEB)
Dawn K. Manley
2003-04-01
Early detection, identification, and warning are essential to minimize casualties from a biological attack. For covert attacks, sick people are likely to provide the first indication of an attack. An enhanced medical surveillance system that synthesizes distributed health indicator information and rapidly analyzes the information can dramatically increase the number of lives saved. Current surveillance methods to detect both biological attacks and natural outbreaks are hindered by factors such as distributed ownership of information, incompatible data storage and analysis programs, and patient privacy concerns. Moreover, because data are not widely shared, few data mining algorithms have been tested on and applied to diverse health indicator data. This project addressed both integration of multiple data sources and development and integration of analytical tools for rapid detection of disease outbreaks. As a first prototype, we developed an application to query and display distributed patient records. This application incorporated need-to-know access control and incorporated data from standard commercial databases. We developed and tested two different algorithms for outbreak recognition. The first is a pattern recognition technique that searches for space-time data clusters that may signal a disease outbreak. The second is a genetic algorithm to design and train neural networks (GANN) that we applied toward disease forecasting. We tested these algorithms against influenza, respiratory illness, and Dengue Fever data. Through this LDRD in combination with other internal funding, we delivered a distributed simulation capability to synthesize disparate information and models for earlier recognition and improved decision-making in the event of a biological attack. The architecture incorporates user feedback and control so that a user's decision inputs can impact the scenario outcome as well as integrated security and role-based access-control for communicating
Analytical model for local scour prediction around hydrokinetic turbine foundations
Musa, M.; Heisel, M.; Hill, C.; Guala, M.
2017-12-01
Marine and Hydrokinetic renewable energy is an emerging sustainable and secure technology which produces clean energy harnessing water currents from mostly tidal and fluvial waterways. Hydrokinetic turbines are typically anchored at the bottom of the channel, which can be erodible or non-erodible. Recent experiments demonstrated the interactions between operating turbines and an erodible surface with sediment transport, resulting in a remarkable localized erosion-deposition pattern significantly larger than those observed by static in-river construction such as bridge piers, etc. Predicting local scour geometry at the base of hydrokinetic devices is extremely important during foundation design, installation, operation, and maintenance (IO&M), and long-term structural integrity. An analytical modeling framework is proposed applying the phenomenological theory of turbulence to the flow structures that promote the scouring process at the base of a turbine. The evolution of scour is directly linked to device operating conditions through the turbine drag force, which is inferred to locally dictate the energy dissipation rate in the scour region. The predictive model is validated using experimental data obtained at the University of Minnesota's St. Anthony Falls Laboratory (SAFL), covering two sediment mobility regimes (clear water and live bed), different turbine designs, hydraulic parameters, grain size distribution and bedform types. The model is applied to a potential prototype scale deployment in the lower Mississippi River, demonstrating its practical relevance and endorsing the feasibility of hydrokinetic energy power plants in large sandy rivers. Multi-turbine deployments are further studied experimentally by monitoring both local and non-local geomorphic effects introduced by a twelve turbine staggered array model installed in a wide channel at SAFL. Local scour behind each turbine is well captured by the theoretical predictive model. However, multi
Simple analytical model of evapotranspiration in the presence of roots.
Cejas, Cesare M; Hough, L A; Castaing, Jean-Christophe; Frétigny, Christian; Dreyfus, Rémi
2014-10-01
Evaporation of water out of a soil involves complicated and well-debated mechanisms. When plant roots are added into the soil, water transfer between the soil and the outside environment is even more complicated. Indeed, plants provide an additional process of water transfer. Water is pumped by the roots, channeled to the leaf surface, and released into the surrounding air by a process called transpiration. Prediction of the evapotranspiration of water over time in the presence of roots helps keep track of the amount of water that remains in the soil. Using a controlled visual setup of a two-dimensional model soil consisting of monodisperse glass beads, we perform experiments on actual roots grown under different relative humidity conditions. We record the total water mass loss in the medium and the position of the evaporating front that forms within the medium. We then develop a simple analytical model that predicts the position of the evaporating front as a function of time as well as the total amount of water that is lost from the medium due to the combined effects of evaporation and transpiration. The model is based on fundamental principles of evaporation fluxes and includes empirical assumptions on the quantity of open stomata in the leaves, where water transpiration occurs. Comparison between the model and experimental results shows excellent prediction of the position of the evaporating front as well as the total mass loss from evapotranspiration in the presence of roots. The model also provides a way to predict the lifetime of a plant.
Chen, Xin; Sánchez-Arriaga, Gonzalo
2018-02-01
To model the sheath structure around an emissive probe with cylindrical geometry, the Orbital-Motion theory takes advantage of three conserved quantities (distribution function, transverse energy, and angular momentum) to transform the stationary Vlasov-Poisson system into a single integro-differential equation. For a stationary collisionless unmagnetized plasma, this equation describes self-consistently the probe characteristics. By solving such an equation numerically, parametric analyses for the current-voltage (IV) and floating-potential (FP) characteristics can be performed, which show that: (a) for strong emission, the space-charge effects increase with probe radius; (b) the probe can float at a positive potential relative to the plasma; (c) a smaller probe radius is preferred for the FP method to determine the plasma potential; (d) the work function of the emitting material and the plasma-ion properties do not influence the reliability of the floating-potential method. Analytical analysis demonstrates that the inflection point of an IV curve for non-emitting probes occurs at the plasma potential. The flat potential is not a self-consistent solution for emissive probes.
Analytical model of neutral gas shielding for hydrogen pellet ablation
Energy Technology Data Exchange (ETDEWEB)
Kuteev, Boris V.; Tsendin, Lev D. [State Technical Univ., St. Petersburg (Russian Federation)
2001-11-01
A kinetic gasdynamic scaling for hydrogen pellet ablation is obtained in terms of a neural gas shielding model using both numerical and analytical approaches. The scaling on plasma and pellet parameters proposed in the monoenergy approximation by Milora and Foster dR{sub pe}/dt{approx}S{sub n}{sup 2/3}R{sub p}{sup -2/3}q{sub eo}{sup 1/3}m{sub i}{sup -1/3} is confirmed. Here R{sub p} is the pellet radius, S{sub n} is the optical thickness of a cloud, q{sub eo} is the electron energy flux density and m{sub i} is the molecular mass. Only the numeral factor is approximately two times less than that for the monoenergy approach. Due to this effect, the pellet ablation rates, which were obtained by Kuteev on the basis of the Milora scaling, should be reduced by a factor of 1.7. Such a modification provides a reasonable agreement (even at high plasma parameters) between the two-dimensional kinetic model and the one-dimensional monoenergy approximation validated in contemporary tokamak experiments. As the could (in the kinetic approximation) is significantly thicker than that for the monoenergy case as well as the velocities of the gas flow are much slower, the relative effect of plasma and magnetic shielding on the ablation rate is strongly reduced. (author)
INCAS: an analytical model to describe displacement cascades
International Nuclear Information System (INIS)
Jumel, Stephanie; Claude Van-Duysen, Jean
2004-01-01
REVE (REactor for Virtual Experiments) is an international project aimed at developing tools to simulate neutron irradiation effects in Light Water Reactor materials (Fe, Ni or Zr-based alloys). One of the important steps of the project is to characterise the displacement cascades induced by neutrons. Accordingly, the Department of Material Studies of Electricite de France developed an analytical model based on the binary collision approximation. This model, called INCAS (INtegration of CAScades), was devised to be applied on pure elements; however, it can also be used on diluted alloys (reactor pressure vessel steels, etc.) or alloys composed of atoms with close atomic numbers (stainless steels, etc.). INCAS describes displacement cascades by taking into account the nuclear collisions and electronic interactions undergone by the moving atoms. In particular, it enables to determine the mean number of sub-cascades induced by a PKA (depending on its energy) as well as the mean energy dissipated in each of them. The experimental validation of INCAS requires a large effort and could not be carried out in the framework of the study. However, it was verified that INCAS results are in conformity with those obtained from other approaches. As a first application, INCAS was applied to determine the sub-cascade spectrum induced in iron by the neutron spectrum corresponding to the central channel of the High Flux Irradiation Reactor of Oak Ridge National Laboratory
Analytical model for an electrostatically actuated miniature diaphragm compressor
International Nuclear Information System (INIS)
Sathe, Abhijit A; Groll, Eckhard A; Garimella, Suresh V
2008-01-01
This paper presents a new analytical approach for quasi-static modeling of an electrostatically actuated diaphragm compressor that could be employed in a miniature scale refrigeration system. The compressor consists of a flexible circular diaphragm clamped at its circumference. A conformal chamber encloses the diaphragm completely. The membrane and the chamber surfaces are coated with metallic electrodes. A potential difference applied between the diaphragm and the chamber pulls the diaphragm toward the chamber surface progressively from the outer circumference toward the center. This zipping actuation reduces the volume available to the refrigerant gas, thereby increasing its pressure. A segmentation technique is proposed for analysis of the compressor by which the domain is divided into multiple segments for each of which the forces acting on the diaphragm are estimated. The pull-down voltage to completely zip each individual segment is thus obtained. The required voltage for obtaining a specific pressure rise in the chamber can thus be determined. Predictions from the model compare well with other simulation results from the literature, as well as to experimental measurements of the diaphragm displacement and chamber pressure rise in a custom-built setup
Probing the conformation of FhaC with small-angle neutron scattering and molecular modeling.
Gabel, Frank; Lensink, Marc F; Clantin, Bernard; Jacob-Dubuisson, Françoise; Villeret, Vincent; Ebel, Christine
2014-07-01
Probing the solution structure of membrane proteins represents a formidable challenge, particularly when using small-angle scattering. Detergent molecules often present residual scattering contributions even at their match point in small-angle neutron scattering (SANS) measurements. Here, we studied the conformation of FhaC, the outer-membrane, β-barrel transporter of the Bordetella pertussis filamentous hemagglutinin adhesin. SANS measurements were performed on homogeneous solutions of FhaC solubilized in n-octyl-d17-βD-glucoside and on a variant devoid of the α helix H1, which critically obstructs the FhaC pore, in two solvent conditions corresponding to the match points of the protein and the detergent, respectively. Protein-bound detergent amounted to 142 ± 10 mol/mol as determined by analytical ultracentrifugation. By using molecular modeling and starting from three distinct conformations of FhaC and its variant embedded in lipid bilayers, we generated ensembles of protein-detergent arrangement models with 120-160 detergent molecules. The scattered curves were back-calculated for each model and compared with experimental data. Good fits were obtained for relatively compact, connected detergent belts, which occasionally displayed small detergent-free patches on the outer surface of the β barrel. The combination of SANS and modeling clearly enabled us to infer the solution structure of FhaC, with H1 inside the pore as in the crystal structure. We believe that our strategy of combining explicit atomic detergent modeling with SANS measurements has significant potential for structural studies of other detergent-solubilized membrane proteins. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.
Small-scale engagement model with arrivals: analytical solutions
International Nuclear Information System (INIS)
Engi, D.
1977-04-01
This report presents an analytical model of small-scale battles. The specific impetus for this effort was provided by a need to characterize hypothetical battles between guards at a nuclear facility and their potential adversaries. The solution procedure can be used to find measures of a number of critical parameters; for example, the win probabilities and the expected duration of the battle. Numerical solutions are obtainable if the total number of individual combatants on the opposing sides is less than 10. For smaller force size battles, with one or two combatants on each side, symbolic solutions can be found. The symbolic solutions express the output parameters abstractly in terms of symbolic representations of the input parameters while the numerical solutions are expressed as numerical values. The input parameters are derived from the probability distributions of the attrition and arrival processes. The solution procedure reduces to solving sets of linear equations that have been constructed from the input parameters. The approach presented in this report does not address the problems associated with measuring the inputs. Rather, this report attempts to establish a relatively simple structure within which small-scale battles can be studied
Analytical and numerical models of transport in porous cementitious materials
International Nuclear Information System (INIS)
Garboczi, E.J.; Bentz, D.P.
1990-01-01
Most chemical and physical processes that degrade cementitious materials are dependent on an external source of either water or ions or both. Understanding the rates of these processes at the microstructural level is necessary in order to develop a sound scientific basis for the prediction and control of the service life of cement-based materials, especially for radioactive-waste containment materials that are required to have service lives on the order of hundreds of years. An important step in developing this knowledge is to understand how transport coefficients, such as diffusivity and permeability, depend on the pore structure. Fluid flow under applied pressure gradients and ionic diffusion under applied concentration gradients are important transport mechanisms that take place in the pore space of cementitious materials. This paper describes: (1) a new analytical percolation-theory-based equation for calculating the permeability of porous materials, (2) new computational methods for computing effective diffusivities of microstructural models or digitized images of actual porous materials, and (3) a new digitized-image mercury intrusion simulation technique
Using visual analytics model for pattern matching in surveillance data
Habibi, Mohammad S.
2013-03-01
In a persistent surveillance system huge amount of data is collected continuously and significant details are labeled for future references. In this paper a method to summarize video data as a result of identifying events based on these tagged information is explained, leading to concise description of behavior within a section of extended recordings. An efficient retrieval of various events thus becomes the foundation for determining a pattern in surveillance system observations, both in its extended and fragmented versions. The patterns consisting of spatiotemporal semantic contents are extracted and classified by application of video data mining on generated ontology, and can be matched based on analysts interest and rules set forth for decision making. The proposed extraction and classification method used in this paper uses query by example for retrieving similar events containing relevant features, and is carried out by data aggregation. Since structured data forms majority of surveillance information this Visual Analytics model employs KD-Tree approach to group patterns in variant space and time, thus making it convenient to identify and match any abnormal burst of pattern detected in a surveillance video. Several experimental video were presented to viewers to analyze independently and were compared with the results obtained in this paper to demonstrate the efficiency and effectiveness of the proposed technique.
Analytical model for minority games with evolutionary learning
Campos, Daniel; Méndez, Vicenç; Llebot, Josep E.; Hernández, Germán A.
2010-06-01
In a recent work [D. Campos, J.E. Llebot, V. Méndez, Theor. Popul. Biol. 74 (2009) 16] we have introduced a biological version of the Evolutionary Minority Game that tries to reproduce the intraspecific competition for limited resources in an ecosystem. In comparison with the complex decision-making mechanisms used in standard Minority Games, only two extremely simple strategies ( juveniles and adults) are accessible to the agents. Complexity is introduced instead through an evolutionary learning rule that allows younger agents to learn taking better decisions. We find that this game shows many of the typical properties found for Evolutionary Minority Games, like self-segregation behavior or the existence of an oscillation phase for a certain range of the parameter values. However, an analytical treatment becomes much easier in our case, taking advantage of the simple strategies considered. Using a model consisting of a simple dynamical system, the phase diagram of the game (which differentiates three phases: adults crowd, juveniles crowd and oscillations) is reproduced.
An analytical study of various telecomminication networks using markov models
Ramakrishnan, M.; Jayamani, E.; Ezhumalai, P.
2015-04-01
The main aim of this paper is to examine issues relating to the performance of various Telecommunication networks, and applied queuing theory for better design and improved efficiency. Firstly, giving an analytical study of queues deals with quantifying the phenomenon of waiting lines using representative measures of performances, such as average queue length (on average number of customers in the queue), average waiting time in queue (on average time to wait) and average facility utilization (proportion of time the service facility is in use). In the second, using Matlab simulator, summarizes the finding of the investigations, from which and where we obtain results and describing methodology for a) compare the waiting time and average number of messages in the queue in M/M/1 and M/M/2 queues b) Compare the performance of M/M/1 and M/D/1 queues and study the effect of increasing the number of servers on the blocking probability M/M/k/k queue model.
Analytical models for total dose ionization effects in MOS devices.
Energy Technology Data Exchange (ETDEWEB)
Campbell, Phillip Montgomery; Bogdan, Carolyn W.
2008-08-01
MOS devices are susceptible to damage by ionizing radiation due to charge buildup in gate, field and SOI buried oxides. Under positive bias holes created in the gate oxide will transport to the Si / SiO{sub 2} interface creating oxide-trapped charge. As a result of hole transport and trapping, hydrogen is liberated in the oxide which can create interface-trapped charge. The trapped charge will affect the threshold voltage and degrade the channel mobility. Neutralization of oxidetrapped charge by electron tunneling from the silicon and by thermal emission can take place over long periods of time. Neutralization of interface-trapped charge is not observed at room temperature. Analytical models are developed that account for the principal effects of total dose in MOS devices under different gate bias. The intent is to obtain closed-form solutions that can be used in circuit simulation. Expressions are derived for the aging effects of very low dose rate radiation over long time periods.
McCormick, Keith; Wei, Bowen
2017-01-01
IBM SPSS Modeler allows quick, efficient predictive analytics and insight building from your data, and is a popularly used data mining tool. This book will guide you through the data mining process, and presents relevant statistical methods which are used to build predictive models and conduct other analytic tasks using IBM SPSS Modeler. From ...
McCormick, Keith; Wei, Bowen
2017-01-01
IBM SPSS Modeler allows quick, efficient predictive analytics and insight building from your data, and is a popularly used data mining tool. This book will guide you through the data mining process, and presents relevant statistical methods which are used to build predictive models and conduct other analytic tasks using IBM SPSS Modeler. From ...
Determining passive cooling limits in CPV using an analytical thermal model
Gualdi, Federico; Arenas, Osvaldo; Vossier, Alexis; Dollet, Alain; Aimez, Vincent; Arès, Richard
2013-09-01
We propose an original thermal analytical model aiming to predict the practical limits of passive cooling systems for high concentration photovoltaic modules. The analytical model is described and validated by comparison with a commercial 3D finite element model. The limiting performances of flat plate cooling systems in natural convection are then derived and discussed.
Analytical model of stemwood growth in relation to nitrogen supply.
Dewar, Roderick C.; McMurtrie, Ross E.
1996-01-01
We derived a simplified version of a previously published process-based model of forest productivity and used it to gain information about the dependence of stemwood growth on nitrogen supply. The simplifications we made led to the following general expression for stemwood carbon (c(w)) as a function of stand age (t), which shows explicitly the main factors involved: c(w)(t) = eta(w)G*/ micro (w)(1 - lambdae(- micro (w)t) - micro (w)e(-lambdat)/lambda - micro (w)), where eta(w) is the fraction of total carbon production (G) allocated to stemwood, G* is the equilibrium value of G at canopy closure, lambda describes the rate at which G approaches G*, and micro (w) is the combined specific rate of stemwood maintenance respiration and senescence. According to this equation, which describes a sigmoidal growth curve, c(w) is zero initially and asymptotically approaches eta(w)G*/ micro (w) with the rate of approach dependent on lambda and micro (w). We used this result to derive corresponding expressions for the maximum mean annual stem-wood volume increment (Y) and optimal rotation length (T). By calculating the quantities G* and lambda (which characterize the variation of carbon production with stand age) as functions of the supply rate of plant-available nitrogen (U(o)), we estimated the responses of Y and T to changes in U(o). For a plausible set of parameter values, as U(o) increased from 50 to 150 kg N ha(-1) year(-1), Y increased approximately linearly from 8 to 25 m(3) ha(-1) year(-1) (mainly as a result of increasing G*), whereas T decreased from 21 to 18 years (due to increasing lambda). The sensitivity of Y and T to other model parameters was also investigated. The analytical model provides a useful basis for examining the effects of changes in climate and nutrient supply on sustainable forest productivity, and may also help in interpreting the behavior of more complex process-based models of forest growth.
Touitou, Jamal; Burch, Robbie; Hardacre, Christopher; McManus, Colin; Morgan, Kevin; Sá, Jacinto; Goguet, Alexandre
2013-05-21
This paper reports the detailed description and validation of a fully automated, computer controlled analytical method to spatially probe the gas composition and thermal characteristics in packed bed systems. As an exemplar, we have examined a heterogeneously catalysed gas phase reaction within the bed of a powdered oxide supported metal catalyst. The design of the gas sampling and the temperature recording systems are disclosed. A stationary capillary with holes drilled in its wall and a moveable reactor coupled with a mass spectrometer are used to enable sampling and analysis. This method has been designed to limit the invasiveness of the probe on the reactor by using the smallest combination of thermocouple and capillary which can be employed practically. An 80 μm (O.D.) thermocouple has been inserted in a 250 μm (O.D.) capillary. The thermocouple is aligned with the sampling holes to enable both the gas composition and temperature profiles to be simultaneously measured at equivalent spatially resolved positions. This analysis technique has been validated by studying CO oxidation over a 1% Pt/Al2O3 catalyst and the spatial resolution profiles of chemical species concentrations and temperature as a function of the axial position within the catalyst bed are reported.
A genetic algorithm-based job scheduling model for big data analytics.
Lu, Qinghua; Li, Shanshan; Zhang, Weishan; Zhang, Lei
Big data analytics (BDA) applications are a new category of software applications that process large amounts of data using scalable parallel processing infrastructure to obtain hidden value. Hadoop is the most mature open-source big data analytics framework, which implements the MapReduce programming model to process big data with MapReduce jobs. Big data analytics jobs are often continuous and not mutually separated. The existing work mainly focuses on executing jobs in sequence, which are often inefficient and consume high energy. In this paper, we propose a genetic algorithm-based job scheduling model for big data analytics applications to improve the efficiency of big data analytics. To implement the job scheduling model, we leverage an estimation module to predict the performance of clusters when executing analytics jobs. We have evaluated the proposed job scheduling model in terms of feasibility and accuracy.
Yu, Zhitao; Miller, Franklin; Pfotenhauer, John M.
2017-12-01
Both a numerical and analytical model of the heat and mass transfer processes in a CO2, N2 mixture gas de-sublimating cross-flow finned duct heat exchanger system is developed to predict the heat transferred from a mixture gas to liquid nitrogen and the de-sublimating rate of CO2 in the mixture gas. The mixture gas outlet temperature, liquid nitrogen outlet temperature, CO2 mole fraction, temperature distribution and de-sublimating rate of CO2 through the whole heat exchanger was computed using both the numerical and analytic model. The numerical model is built using EES [1] (engineering equation solver). According to the simulation, a cross-flow finned duct heat exchanger can be designed and fabricated to validate the models. The performance of the heat exchanger is evaluated as functions of dimensionless variables, such as the ratio of the mass flow rate of liquid nitrogen to the mass flow rate of inlet flue gas.
Ship Impact Study: Analytical Approaches and Finite Element Modeling
Directory of Open Access Journals (Sweden)
Pawel Woelke
2012-01-01
Full Text Available The current paper presents the results of a ship impact study conducted using various analytical approaches available in the literature with the results obtained from detailed finite element analysis. Considering a typical container vessel impacting a rigid wall with an initial speed of 10 knots, the study investigates the forces imparted on the struck obstacle, the energy dissipated through inelastic deformation, penetration, local deformation patterns, and local failure of the ship elements. The main objective of the paper is to study the accuracy and generality of the predictions of the vessel collision forces, obtained by means of analytical closed-form solutions, in reference to detailed finite element analyses. The results show that significant discrepancies between simplified analytical approaches and detailed finite element analyses can occur, depending on the specific impact scenarios under consideration.
A new gas cooling model for semi-analytic galaxy formation models
Hou, Jun; Lacey, Cedric G.; Frenk, Carlos S.
2018-03-01
Semi-analytic galaxy formation models are widely used to gain insight into the astrophysics of galaxy formation and in model testing, parameter space searching and mock catalogue building. In this work, we present a new model for gas cooling in haloes in semi-analytic models, which improves over previous cooling models in several ways. Our new treatment explicitly includes the evolution of the density profile of the hot gas driven by the growth of the dark matter halo and by the dynamical adjustment of the gaseous corona as gas cools down. The effect of the past cooling history on the current mass cooling rate is calculated more accurately, by doing an integral over the past history. The evolution of the hot gas angular momentum profile is explicitly followed, leading to a self-consistent and more detailed calculation of the angular momentum of the cooled down gas. This model predicts higher cooled down masses than the cooling models previously used in GALFORM, closer to the predictions of the cooling models in L-GALAXIES and MORGANA, even though those models are formulated differently. It also predicts cooled down angular momenta that are higher than in previous GALFORM cooling models, but generally lower than the predictions of L-GALAXIES and MORGANA. When used in a full galaxy formation model, this cooling model improves the predictions for early-type galaxy sizes in GALFORM.
Directory of Open Access Journals (Sweden)
Marc R Birtwistle
Full Text Available Numerous unimolecular, genetically-encoded Förster Resonance Energy Transfer (FRET probes for monitoring biochemical activities in live cells have been developed over the past decade. As these probes allow for collection of high frequency, spatially resolved data on signaling events in live cells and tissues, they are an attractive technology for obtaining data to develop quantitative, mathematical models of spatiotemporal signaling dynamics. However, to be useful for such purposes the observed FRET from such probes should be related to a biological quantity of interest through a defined mathematical relationship, which is straightforward when this relationship is linear, and can be difficult otherwise. First, we show that only in rare circumstances is the observed FRET linearly proportional to a biochemical activity. Therefore in most cases FRET measurements should only be compared either to explicitly modeled probes or to concentrations of products of the biochemical activity, but not to activities themselves. Importantly, we find that FRET measured by standard intensity-based, ratiometric methods is inherently non-linear with respect to the fraction of probes undergoing FRET. Alternatively, we find that quantifying FRET either via (1 fluorescence lifetime imaging (FLIM or (2 ratiometric methods where the donor emission intensity is divided by the directly-excited acceptor emission intensity (denoted R(alt is linear with respect to the fraction of probes undergoing FRET. This linearity property allows one to calculate the fraction of active probes based on the FRET measurement. Thus, our results suggest that either FLIM or ratiometric methods based on R(alt are the preferred techniques for obtaining quantitative data from FRET probe experiments for mathematical modeling purposes.
Analytical model of transient thermal effect on convectional cooled ...
Indian Academy of Sciences (India)
Abstract. The transient analytical solutions of temperature distribution, stress, strain and optical path difference in convectional cooled end-pumped laser rod are derived. The results are compared with other works and good agreements are found. The effects of increasing the edge cooling and face cooling are studied.
Modeling and analytical simulation of high-temperature gas filtration ...
African Journals Online (AJOL)
High temperature filtration in combustion and gasification processes is a highly interdisciplinary field. Thus, particle technology in general has to be supported by elements of physics, chemistry, thermodynamics and heat and mass transfer processes. Presented in this paper is the analytical method for describing ...
Ethics, Big Data, and Analytics: A Model for Application.
Willis, James E, III
2013-01-01
The use of big data and analytics to predict student success presents unique ethical questions for higher education administrators relating to the nature of knowledge; in education, "to know" entails an obligation to act on behalf of the student. The Potter Box framework can help administrators address these questions and provide a framework for action.
Modelling a flows in supply chain with analytical models: Case of a chemical industry
Benhida, Khalid; Azougagh, Yassine; Elfezazi, Said
2016-02-01
This study is interested on the modelling of the logistics flows in a supply chain composed on a production sites and a logistics platform. The contribution of this research is to develop an analytical model (integrated linear programming model), based on a case study of a real company operating in the phosphate field, considering a various constraints in this supply chain to resolve the planning problems for a better decision-making. The objectives of this model is to determine and define the optimal quantities of different products to route, to and from the various entities in the supply chain studied.
An improved model for the oPtImal Measurement Probes Allocation tool
International Nuclear Information System (INIS)
Sterle, C.; Neto, A.C.; De Tommasi, G.
2015-01-01
Highlights: • The problem of optimally allocating the probes of a diagnostic system is tackled. • The problem is decomposed in two consecutive optimization problems. • Two original ILP models are proposed and sequentially solved to optimality. • The proposed ILP models improve and extend the previous work present in literature. • Real size instances have been optimally solved with very low computation time. - Abstract: The oPtImal Measurement Probes Allocation (PIMPA) tool has been recently proposed in [1] to maximize the reliability of a tokamak diagnostic system against the failure of one or more of the processing nodes. PIMPA is based on the solution of integer linear programming (ILP) problems, and it minimizes the effect of the failure of a data acquisition component. The first formulation of the PIMPA model did not support the concept of individual slots. This work presents an improved ILP model that addresses the above mentioned problem, by taking into account all the individual probes.
Analytical Model of Water Flow in Coal with Active Matrix
Siemek, Jakub; Stopa, Jerzy
2014-12-01
This paper presents new analytical model of gas-water flow in coal seams in one dimension with emphasis on interactions between water flowing in cleats and coal matrix. Coal as a flowing system, can be viewed as a solid organic material consisting of two flow subsystems: a microporous matrix and a system of interconnected macropores and fractures. Most of gas is accumulated in the microporous matrix, where the primary flow mechanism is diffusion. Fractures and cleats existing in coal play an important role as a transportation system for macro scale flow of water and gas governed by Darcy's law. The coal matrix can imbibe water under capillary forces leading to exchange of mass between fractures and coal matrix. In this paper new partial differential equation for water saturation in fractures has been formulated, respecting mass exchange between coal matrix and fractures. Exact analytical solution has been obtained using the method of characteristics. The final solution has very simple form that may be useful for practical engineering calculations. It was observed that the rate of exchange of mass between the fractures and the coal matrix is governed by an expression which is analogous to the Newton cooling law known from theory of heat exchange, but in present case the mass transfer coefficient depends not only on coal and fluid properties but also on time and position. The constant term of mass transfer coefficient depends on relation between micro porosity and macro porosity of coal, capillary forces, and microporous structure of coal matrix. This term can be expressed theoretically or obtained experimentally. W artykule zaprezentowano nowy model matematyczny przepływu wody i gazu w jednowymiarowej warstwie węglowej z uwzględnieniem wymiany masy między systemem szczelin i matrycą węglową. Węgiel jako system przepływowy traktowany jest jako układ o podwójnej porowatości i przepuszczalności, składający się z mikroporowatej matrycy węglowej oraz z
Analytical modeling of electrical characteristics of coaxial nanowire FETs
Kargar, Alireza; Ghayour, Rahim
2011-03-01
In this paper, an analytical approach based on ballistic current transport is presented to investigate the electrical characteristics of the coaxial nanowire field effect transistor (CNWFET). The potential distribution along the nanowire is derived analytically by applying Laplace equation. In addition to application of WKB approximation and ballistic transport, tunneling process and quantum state of energy are implemented to determine the amount of electron transport along the nanowire from the source to the drain terminals. To consider the tunneling phenomena, WKB approximation is used and the transmission coefficients on both sides of the channel are obtained separately. In ballistic regime, an expression for channel current in terms of the bias voltages and Schottky barrier height (SBH) is derived. The results confirm a close correlation between the current equation of this work and the results presented via other approaches.
The use of analytical models in human-computer interface design
Gugerty, Leo
1993-01-01
Recently, a large number of human-computer interface (HCI) researchers have investigated building analytical models of the user, which are often implemented as computer models. These models simulate the cognitive processes and task knowledge of the user in ways that allow a researcher or designer to estimate various aspects of an interface's usability, such as when user errors are likely to occur. This information can lead to design improvements. Analytical models can supplement design guidelines by providing designers rigorous ways of analyzing the information-processing requirements of specific tasks (i.e., task analysis). These models offer the potential of improving early designs and replacing some of the early phases of usability testing, thus reducing the cost of interface design. This paper describes some of the many analytical models that are currently being developed and evaluates the usefulness of analytical models for human-computer interface design. This paper will focus on computational, analytical models, such as the GOMS model, rather than less formal, verbal models, because the more exact predictions and task descriptions of computational models may be useful to designers. The paper also discusses some of the practical requirements for using analytical models in complex design organizations such as NASA.
Probing dark matter models with neutrinos from the Galactic center
Erkoca, Arif Emre; Reno, Mary Hall; Sarcevic, Ina
2010-01-01
We calculate the contained and upward muon and shower fluxes due to neutrinos produced via dark matter annihilation or decay in the Galactic center. We consider dark matter models in which the dark matter particle is a gravitino, a Kaluza-Klein particle and a particle in leptophilic models. The Navarro-Frenk-White profile for the dark matter density distribution in the Galaxy is used. We incorporate neutrino oscillations by assuming maximal mixing and parametrize our results for muon and show...
An Analytical Hierarchy Process Model for the Evaluation of College Experimental Teaching Quality
Yin, Qingli
2013-01-01
Taking into account the characteristics of college experimental teaching, through investigaton and analysis, evaluation indices and an Analytical Hierarchy Process (AHP) model of experimental teaching quality have been established following the analytical hierarchy process method, and the evaluation indices have been given reasonable weights. An…
An Analytic Hierarchy Process for School Quality and Inspection: Model Development and Application
Al Qubaisi, Amal; Badri, Masood; Mohaidat, Jihad; Al Dhaheri, Hamad; Yang, Guang; Al Rashedi, Asma; Greer, Kenneth
2016-01-01
Purpose: The purpose of this paper is to develop an analytic hierarchy planning-based framework to establish criteria weights and to develop a school performance system commonly called school inspections. Design/methodology/approach: The analytic hierarchy process (AHP) model uses pairwise comparisons and a measurement scale to generate the…
Environmental vulnerability assessment using Grey Analytic Hierarchy Process based model
International Nuclear Information System (INIS)
Sahoo, Satiprasad; Dhar, Anirban; Kar, Amlanjyoti
2016-01-01
Environmental management of an area describes a policy for its systematic and sustainable environmental protection. In the present study, regional environmental vulnerability assessment in Hirakud command area of Odisha, India is envisaged based on Grey Analytic Hierarchy Process method (Grey–AHP) using integrated remote sensing (RS) and geographic information system (GIS) techniques. Grey–AHP combines the advantages of classical analytic hierarchy process (AHP) and grey clustering method for accurate estimation of weight coefficients. It is a new method for environmental vulnerability assessment. Environmental vulnerability index (EVI) uses natural, environmental and human impact related factors, e.g., soil, geology, elevation, slope, rainfall, temperature, wind speed, normalized difference vegetation index, drainage density, crop intensity, agricultural DRASTIC value, population density and road density. EVI map has been classified into four environmental vulnerability zones (EVZs) namely: ‘low’, ‘moderate’ ‘high’, and ‘extreme’ encompassing 17.87%, 44.44%, 27.81% and 9.88% of the study area, respectively. EVI map indicates that the northern part of the study area is more vulnerable from an environmental point of view. EVI map shows close correlation with elevation. Effectiveness of the zone classification is evaluated by using grey clustering method. General effectiveness is in between “better” and “common classes”. This analysis demonstrates the potential applicability of the methodology. - Highlights: • Environmental vulnerability zone identification based on Grey Analytic Hierarchy Process (AHP) • The effectiveness evaluation by means of a grey clustering method with support from AHP • Use of grey approach eliminates the excessive dependency on the experience of experts.
Analytical models of optical refraction in the troposphere.
Nener, Brett D; Fowkes, Neville; Borredon, Laurent
2003-05-01
An extremely accurate but simple asymptotic description (with known error) is obtained for the path of a ray propagating over a curved Earth with radial variations in refractive index. The result is sufficiently simple that analytic solutions for the path can be obtained for linear and quadratic index profiles. As well as rendering the inverse problem trivial for these profiles, this formulation shows that images are uniformly magnified in the vertical direction when viewed through a quadratic refractive-index profile. Nonuniform vertical distortions occur for higher-order refractive-index profiles.
Directory of Open Access Journals (Sweden)
John (Jack P. Riegel III
2016-04-01
Full Text Available Historically, there has been little correlation between the material properties used in (1 empirical formulae, (2 analytical formulations, and (3 numerical models. The various regressions and models may each provide excellent agreement for the depth of penetration into semi-infinite targets. But the input parameters for the empirically based procedures may have little in common with either the analytical model or the numerical model. This paper builds on previous work by Riegel and Anderson (2014 to show how the Effective Flow Stress (EFS strength model, based on empirical data, can be used as the average flow stress in the analytical Walker–Anderson Penetration model (WAPEN (Anderson and Walker, 1991 and how the same value may be utilized as an effective von Mises yield strength in numerical hydrocode simulations to predict the depth of penetration for eroding projectiles at impact velocities in the mechanical response regime of the materials. The method has the benefit of allowing the three techniques (empirical, analytical, and numerical to work in tandem. The empirical method can be used for many shot line calculations, but more advanced analytical or numerical models can be employed when necessary to address specific geometries such as edge effects or layering that are not treated by the simpler methods. Developing complete constitutive relationships for a material can be costly. If the only concern is depth of penetration, such a level of detail may not be required. The effective flow stress can be determined from a small set of depth of penetration experiments in many cases, especially for long penetrators such as the L/D = 10 ones considered here, making it a very practical approach. In the process of performing this effort, the authors considered numerical simulations by other researchers based on the same set of experimental data that the authors used for their empirical and analytical assessment. The goals were to establish a
Emulating Spherical Wave Channel Models in Multi-probe Anechoic Chamber Setups
DEFF Research Database (Denmark)
Fan, Wei; Carreño, Xavier; Nielsen, Jesper Ødum
2015-01-01
Spherical wave channel modeling has attracted huge research attention for massive multiple-input multiple-output (MIMO) and short-distance MIMO systems. Current research work in multi-probe anechoic chamber systems is limited to reproduce radio channels assuming planar wavefronts. There is a need...... to emulate spherical wave channel models in multi-probe anechoic chamber setups. In this paper, a technique based on the field synthesis principle is proposed to approximate spherical waves emitted from arbitrarily located point sources with arbitrary polarizations. Simulation results show that static...... spherical waves can be reproduced with a limited number of probes, and the field synthesis accuracy of spherical wave depends on the location of the source point....
Design Evaluation of Wind Turbine Spline Couplings Using an Analytical Model: Preprint
Energy Technology Data Exchange (ETDEWEB)
Guo, Y.; Keller, J.; Wallen, R.; Errichello, R.; Halse, C.; Lambert, S.
2015-02-01
Articulated splines are commonly used in the planetary stage of wind turbine gearboxes for transmitting the driving torque and improving load sharing. Direct measurement of spline loads and performance is extremely challenging because of limited accessibility. This paper presents an analytical model for the analysis of articulated spline coupling designs. For a given torque and shaft misalignment, this analytical model quickly yields insights into relationships between the spline design parameters and resulting loads; bending, contact, and shear stresses; and safety factors considering various heat treatment methods. Comparisons of this analytical model against previously published computational approaches are also presented.
On the nuclear energy generation rate in a simple analytic stellar model
International Nuclear Information System (INIS)
Haubold, H.J.
1985-01-01
For a shperically symmetric star in quasi-static equilibrium a simple analytic stellar model is presented. The common technique of integration theory of special functions for treating a special solution of the equations of stellar structure is described. As an example the sun can be considered as a fluid in hydrostatic equilibrium. The total net rate of nuclear energy generation, which is equal to the luminosity of the star, is evaluated analytically for a linear density distribution assumed for a simple stellar model. For several analytic representations of the nuclear energy generation rate the luminosity function is evaluated for the presented stellar model in closed form
The influence of NBD fluorescent probe on model membranes containing POPC and DPPC.
Weng, Chi-Jung; Wu, Ju-Ping; Kuo, Ming-Yen; Hsueh, Ya-Wei
2016-03-01
To investigate the effect of fluorescent probe on the properties of membranes, we studied model membranes composed of 1,2- dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1-palmitoyl 2-oleoyl-sn-glycero-3-phosphocholine (POPC) in the presence and absence of fluorescent probe. The morphology of giant unilamellar vesicles (GUVs) has been observed as a function of temperature and composition by fluorescence microscopy using NBD-DOPE or C 6 -NBD-PC as the probe. The phase behavior of model membranes containing no fluorescent probe was investigated by 2 H-NMR spectroscopy. We found that the bright phase observed on GUVs was the fluid phase enriched in POPC and the dark phase was the gel phase enriched in DPPC. NBD-DOPE and C 6 -NBD-PC preferentially participated in the fluid-phase domains when GUVs were in the gel + fluid phase coexistence. Inclusion of both fluorescent probes (1 mol%) lowered the transition temperature of POPC/DPPC membranes. In addition, C 6 -NBD-PC exhibited a stronger effect than NBD-DOPE, which was considered to be associated with the structures of fluorescent molecules.
Seniority mappings for probing phenomenological nuclear boson models
International Nuclear Information System (INIS)
De Kock, E.A.
1988-12-01
The interacting boson model (IBM) and interacting boson-fermion model (IBFM) are discussed. The main ideas of boson mapping of fermion systems are introduced using Holstein-Primakoff and Dyson-Maleev mappings of angular momentum operators. Generalized Dyson-Maleev (GDM) and Holstein-Primakoff (GHP) mappings are included. In fermoin problems, the degrees of freedom of collective motion are described by a collective subalgebra of the complete bifermion subalgebra. GDM mapping of Sp(6) generators, the transformation to collect bosons and truncation to these bosons led to collective sd-boson realization of Sp(6) algebra. This resulted in an IBM-like description of the collective subspace. Non-hermitian and existing hermitian forms are indicated in the assumed structure of an IBM Hamiltonian Boson mapping based on seniority considerations and involving single-j shell approximations of the shell model are examined. One method utilized truncation of a shell model space to a space spanned by monopole (S) and quadrupole (D) pairs. The association between states in truncated fermion and sd-boson spaces constructs boson images of fermion operators by equating boson and fermion matrix elements. To obtain boson images with IBM-like structures, a zero-order approximation was adopted. This approximation retains only N-body terms in the images of N-body fermion operators. A similarity transformation re-expressing GDM images of single-j shell fermion operators in seniority bosons was applied to the GDM image of a general shell model Hamiltonian. Numerical results for the surface-delta interaction show that truncation to s- and d-bosons in the seniority image of a two-body operator is not allowed if N≥2. This transformation was extended to odd fermion systems and applied to the image of the quadrupole pairing interaction. 79 refs., 3 figs., 4 tabs
Detection of the cemento-enamel junction with three different probes: an "in vitro" model
Barendregt, D.S.; van der Velden, U.; Timmerman, M.F.; Bulthuis, H.M.; van der Weijden, G.A.
2008-01-01
Aim: The purpose of the present study was to test the accuracy and precision with which the cemento-enamel junction (CEJ) can be assessed using three commercially available periodontal probes with different tip endings in both deciduous and permanent teeth. Material and Methods: An "in vitro" model
Directory of Open Access Journals (Sweden)
Suresh V.
2016-02-01
Full Text Available In this paper, an analytical model is proposed to predict magnetic flux leakage (MFL signals from the surface defects in ferromagnetic tubes. The analytical expression consists of elliptic integrals of first kind based on the magnetic dipole model. The radial (Bz component of leakage fields is computed from the cylindrical holes in ferromagnetic tubes. The effectiveness of the model has been studied by analyzing MFL signals as a function of the defect parameters and lift-off. The model predicted results are verified with experimental results and a good agreement is observed between the analytical and the experimental results. This analytical expression could be used for quick prediction of MFL signals and also input data for defect reconstructions in inverse MFL problem.
Local probing by use of transparent model materials
Philippe, P.
2017-12-01
The present contribution emphasizes on two distinct examples the benefit with using transparent materials that enable direct visualization within different types of model systems. Our first use of transparent materials investigates the elementary mechanisms involved in soil erosion based on three key ingredients: a) cohesive model materials (i.e. glass beads bonded by solid bridges); b) optical techniques (Refractive Index Matching and Planar Laser Induced Fluorescence [1,2]) ; c) specific mechanical tests to estimate the mechanical strength of the solid bonds. Then, critical shear-stress at erosion onset can be related to tensile strength considering an extension of the classical Shields' number [3,4].Our second example uses a transparent elasto-visco-plastic fluid (Carbopol) as a model of debris flows. Different geometrical configurations allow for an accurate investigation of the flow over an obstacle [5] or a cavity [6], inducing the existence of a dead-zone and consequently of a frontier between solid-like and fluid-like regions that is of particular relevance for debris flows mobilization and deposition. Practically, the hydrodynamics of the flow is investigated by means of high-resolution optical velocimetry (PIV) and underlines a non-monotonous evolution of the shear rate, which increases from zero at the solid-liquid interface, passes through a peak (sometimes leveling off at its maximum value), and returns to zero in a plug zone sufficiently far above the cavity or the obstacle. [1] Philippe P., and Badiane M. Phys. Rev. E 87, 042206 (2013). [2] Dijksman J.A., Rietz F., Lorincz K.A., van Hecke M., and Losert W. Review of Scientific Instruments 83(1), 011301 (2012). [3] Badr S., Gauthier G., and Gondret P. Phys. Fluids 26:023302 (2014). [4] Brunier-Coulin F., Cuéllar P., and Philippe P. Phys. Rev. Fluids 87, 2: 034302 (2017). [5] Luu L.-H., Philippe P., and Chambon G. Phys. Rev. E 91, 013013 (2015). [6] Luu L.-H., Philippe P.; and Chambon G. Journal of
Analytical Model-based Fault Detection and Isolation in Control Systems
DEFF Research Database (Denmark)
Vukic, Z.; Ozbolt, H.; Blanke, M.
1998-01-01
The paper gives an introduction and an overview of the field of fault detection and isolation for control systems. The summary of analytical (quantitative model-based) methodds and their implementation are presented. The focus is given to mthe analytical model-based fault-detection and fault diag...... diagnosis methods, often viewed as the classical or deterministic ones. Emphasis is placed on the algorithms suitable for ship automation, unmanned underwater vehicles, and other systems of automatic control....
3D Analytical Model for a Tubular Linear Induction Generator in a Stirling Cogeneration System
Francois , Pierre; Garcia Burel , Isabelle; BEN AHMED , Hamid; Prevond , Laurent; Multon , Bernard
2007-01-01
International audience; This article sets forth a 3D analytical model of a tubular linear induction generator. In the intended application, the slot and edge effects as well as induced current penetration phenomena within the solid mover cannot be overlooked. Moreover, generator optimization within the present context of cogeneration has necessitated a systemic strategy. Reliance upon an analytical modeling approach that incorporates the array of typically-neglected phenomena has proven essen...
Lifetime of {sup 44}Ti as probe for supernova models
Energy Technology Data Exchange (ETDEWEB)
Goerres, J.; Meissner, J.; Schatz, H.; Stech, E.; Tischhauser, P.; Wiescher, M. [Univ. of Notre Dame, Notre Dame, IN (United States); Bazin, D.; Harkewicz, R.; Hellstroem, M.; Sherrill, B.; Steiner, M. [Michigan State Univ., East Lansing, MI (United States); Boyd, R.N. [Ohio State Univ., Columbus, OH (United States); Buchmann, L. [TRIUMF, Vancouver, BC (Canada); Hartmann, D.H. [Clemson Univ., Clemson, SC (United States); Hinnefeld, J.D. [Indiana Univ. South Bend, South Bend, IN (United States)
1998-06-01
The recent observation of {sup 44}Ti radioactivity in the supernova remnant Cassiopeia A with the Compton Gamma Ray Observatory allows the determination of the absolute amount of {sup 44}Ti. This provides a test for current supernova models. The main uncertainty is the lifetime of {sup 44}Ti. We report a new measurement of the lifetime of {sup 44}Ti applying a novel technique. A mixed radioactive beam containing {sup 44}Ti as well as {sup 22}Na was implanted and the resulting {gamma}-activity was measured. This allowed the determination of the lifetime of {sup 44}Ti relative to the lifetime of {sup 22}Na, {tau} = (87.0 {+-} 1.9) y. With this lifetime, the {sup 44}Ti abundance agrees with theoretical predictions within the remaining observational uncertainties. (orig.)
Probing flame chemistry with MBMS, theory, and modeling
Energy Technology Data Exchange (ETDEWEB)
Westmoreland, P.R. [Univ. of Massachusetts, Amherst (United States)
1993-12-01
The objective is to establish kinetics of combustion and molecular-weight growth in C{sub 3} hydrocarbon flames as part of an ongoing study of flame chemistry. Specific reactions being studied are (1) the growth reactions of C{sub 3}H{sub 5} and C{sub 3}H{sub 3} with themselves and with unsaturated hydrocarbons and (2) the oxidation reactions of O and OH with C{sub 3}`s. This approach combines molecular-beam mass spectrometry (MBMS) experiments on low-pressure flat flames; theoretical predictions of rate constants by thermochemical kinetics, Bimolecular Quantum-RRK, RRKM, and master-equation theory; and whole-flame modeling using full mechanisms of elementary reactions.
Wang, D.; Shprits, Y.; Spasojevic, M.; Zhu, H.; Aseev, N.; Drozdov, A.; Kellerman, A. C.
2017-12-01
In situ satellite observations, theoretical studies and model simulations suggested that chorus waves play a significant role in the dynamic evolution of relativistic electrons in the Earth's radiation belts. In this study, we developed new wave frequency and amplitude models that depend on Magnetic Local Time (MLT)-, L-shell, latitude- and geomagnetic conditions indexed by Kp for upper-band and lower-band chorus waves using measurements from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument onboard the Van Allen Probes. Utilizing the quasi-linear full diffusion code, we calculated corresponding diffusion coefficients in each MLT sector (1 hour resolution) for upper-band and lower-band chorus waves according to the new developed wave models. Compared with former parameterizations of chorus waves, the new parameterizations result in differences in diffusion coefficients that depend on energy and pitch angle. Utilizing obtained diffusion coefficients, lifetime of energetic electrons is parameterized accordingly. In addition, to investigate effects of obtained diffusion coefficients in different MLT sectors and under different geomagnetic conditions, we performed simulations using four-dimensional Versatile Electron Radiation Belt simulations and validated results against observations.
KEEFEKTIFAN PENERAPAN MODEL PEMBELAJARAN KOOPERATIF TIPE PROBING-PROMPTING DENGAN PENILAIAN PRODUK
Directory of Open Access Journals (Sweden)
Himmatul Ulya
2012-06-01
Full Text Available Abstract Tujuan penelitian ini adalah untuk mengetahui apakah pembelajaran kooperatif tipe probing-prompting dengan penilaian produk dan pembelajaran kooperatif tipe probing-prompting materi keliling dan luas lingkaran dapat mencapai ketuntasan belajar dan lebih baik dari pembelajaran ekspositori pada peserta didik kelas VIII. Populasi dalam penelitian ini adalah peserta didik kelas VIII MTs. Nurussalam Gebog Kudus tahun pelajaran 2011/2012. Dengan cara acak terpilih sampel yaitu peserta didik kelas VIIIA dan VIIIC sebagai kelas eksperimen 1 dan 2, serta VIIIB sebagai kelas kontrol. Diperoleh hasil penelitian bahwa rata-rata hasil belajar peserta didik kelas eksperimen 1 sebesar 79,91, kelas eksperimen 2 sebesar 73,21, dan kelas kontrol sebesar 66,10. Dari hasil uji ketuntasan belajar diperoleh peserta didik kelas eksperimen mencapai ketuntasan belajar (individual dan klasikal. Dari hasil uji Anava nilai Sig.= 0,000 < 0,05 artinya ada perbedaan rata-rata, kemudian dilakukan uji lanjut Scheffe menunjukkan adanya perbedaan rata-rata yang signifikan antara masing-masing kelas. Simpulan yang diperoleh adalah pembelajaran kooperatif tipe probing-prompting yang disertai dengan penilaian produk dan pembelajaran kooperatif tipe probing-prompting materi keliling dan luas lingkaran dapat mencapai ketuntasan belajar, model pembelajaran kooperatif tipe probing-prompting dengan penilaian produk lebih baik dari pembelajaran kooperatif tipe probing-prompting, dan pembelajaran kooperatif tipe probing-prompting lebih baik dari pembelajaran ekspositori. The purpose of this study was to determine whether the cooperative learning of probing-prompting by assessing products of circle perimeter and circle area material could reach the completeness learning of students. The population of this study was the students of grade VIII MTs. Nurussalam Gebog Kudus year 2011/2012. Randomly, the selected samples were the students of VIIIA and VIIIC as the experiment classes 1
Hybrid Analytical and Data-Driven Modeling for Feed-Forward Robot Control.
Reinhart, René Felix; Shareef, Zeeshan; Steil, Jochen Jakob
2017-02-08
Feed-forward model-based control relies on models of the controlled plant, e.g., in robotics on accurate knowledge of manipulator kinematics or dynamics. However, mechanical and analytical models do not capture all aspects of a plant's intrinsic properties and there remain unmodeled dynamics due to varying parameters, unmodeled friction or soft materials. In this context, machine learning is an alternative suitable technique to extract non-linear plant models from data. However, fully data-based models suffer from inaccuracies as well and are inefficient if they include learning of well known analytical models. This paper thus argues that feed-forward control based on hybrid models comprising an analytical model and a learned error model can significantly improve modeling accuracy. Hybrid modeling here serves the purpose to combine the best of the two modeling worlds. The hybrid modeling methodology is described and the approach is demonstrated for two typical problems in robotics, i.e., inverse kinematics control and computed torque control. The former is performed for a redundant soft robot and the latter for a rigid industrial robot with redundant degrees of freedom, where a complete analytical model is not available for any of the platforms.
Hybrid Analytical and Data-Driven Modeling for Feed-Forward Robot Control †
Reinhart, René Felix; Shareef, Zeeshan; Steil, Jochen Jakob
2017-01-01
Feed-forward model-based control relies on models of the controlled plant, e.g., in robotics on accurate knowledge of manipulator kinematics or dynamics. However, mechanical and analytical models do not capture all aspects of a plant’s intrinsic properties and there remain unmodeled dynamics due to varying parameters, unmodeled friction or soft materials. In this context, machine learning is an alternative suitable technique to extract non-linear plant models from data. However, fully data-based models suffer from inaccuracies as well and are inefficient if they include learning of well known analytical models. This paper thus argues that feed-forward control based on hybrid models comprising an analytical model and a learned error model can significantly improve modeling accuracy. Hybrid modeling here serves the purpose to combine the best of the two modeling worlds. The hybrid modeling methodology is described and the approach is demonstrated for two typical problems in robotics, i.e., inverse kinematics control and computed torque control. The former is performed for a redundant soft robot and the latter for a rigid industrial robot with redundant degrees of freedom, where a complete analytical model is not available for any of the platforms. PMID:28208697
Hybrid Analytical and Data-Driven Modeling for Feed-Forward Robot Control †
Directory of Open Access Journals (Sweden)
René Felix Reinhart
2017-02-01
Full Text Available Feed-forward model-based control relies on models of the controlled plant, e.g., in robotics on accurate knowledge of manipulator kinematics or dynamics. However, mechanical and analytical models do not capture all aspects of a plant’s intrinsic properties and there remain unmodeled dynamics due to varying parameters, unmodeled friction or soft materials. In this context, machine learning is an alternative suitable technique to extract non-linear plant models from data. However, fully data-based models suffer from inaccuracies as well and are inefficient if they include learning of well known analytical models. This paper thus argues that feed-forward control based on hybrid models comprising an analytical model and a learned error model can significantly improve modeling accuracy. Hybrid modeling here serves the purpose to combine the best of the two modeling worlds. The hybrid modeling methodology is described and the approach is demonstrated for two typical problems in robotics, i.e., inverse kinematics control and computed torque control. The former is performed for a redundant soft robot and the latter for a rigid industrial robot with redundant degrees of freedom, where a complete analytical model is not available for any of the platforms.
HPC in global geo dynamics: Advances in normal-mode analytical modelling
International Nuclear Information System (INIS)
Melini, D.
2009-01-01
Analytical models based on normal-mode theory have been successfully employed for decades in the modeling of global response of the Earth to seismic dislocations, post glacial rebound and wave propagation. Despite their limited capabilities with respect to fully numerical approaches, they are yet a valuable modeling tool, for instance in benchmarking applications or when automated procedures have to be implemented, as in massive inversion problems when a large number of forward models have to be solved. The availability of high-performance computer systems ignited new applications for analytical modeling, allowing to re- move limiting approximations and to carry out extensive simulations on large global datasets.
Force 2025 and Beyond Strategic Force Design Analytic Model
2017-01-12
the methodology used to construct force design models. The Summary section provides a summary of our findings. Background By 2025, a leaner ...designs. We describe a data development methodology that characterizes the data required to construct a force design model using our approach. We...from a model constructed using this methodology in a case study. 15. SUBJECT TERMS Force design, mixed integer programming, optimization, value
Energy demand analytics using coupled technological and economic models
Impacts of a range of policy scenarios on end-use energy demand are examined using a coupling of MARKAL, an energy system model with extensive supply and end-use technological detail, with Inforum LIFT, a large-scale model of the us. economy with inter-industry, government, and c...
Analytical modeling of pipeline failure in multiphase flow due to ...
African Journals Online (AJOL)
This research focuses on the development of a model that can predict pipeline failure due to corrosion in multiphase flows. The role that velocity, density, water cut and other parameters play in predicting corrosion is critically analyzed with Norsok Model. The result shows that velocity plays a key role in corrosion prediction.
A MAGNIFIED GLANCE INTO THE DARK SECTOR: PROBING COSMOLOGICAL MODELS WITH STRONG LENSING IN A1689
International Nuclear Information System (INIS)
Magaña, Juan; Motta, V.; Cárdenas, Victor H.; Verdugo, T.; Jullo, Eric
2015-01-01
In this paper we constrain four alternative models to the late cosmic acceleration in the universe: Chevallier–Polarski–Linder (CPL), interacting dark energy (IDE), Ricci holographic dark energy (HDE), and modified polytropic Cardassian (MPC). Strong lensing (SL) images of background galaxies produced by the galaxy cluster Abell 1689 are used to test these models. To perform this analysis we modify the LENSTOOL lens modeling code. The value added by this probe is compared with other complementary probes: Type Ia supernovae (SN Ia), baryon acoustic oscillations (BAO), and cosmic microwave background (CMB). We found that the CPL constraints obtained for the SL data are consistent with those estimated using the other probes. The IDE constraints are consistent with the complementary bounds only if large errors in the SL measurements are considered. The Ricci HDE and MPC constraints are weak, but they are similar to the BAO, SN Ia, and CMB estimations. We also compute the figure of merit as a tool to quantify the goodness of fit of the data. Our results suggest that the SL method provides statistically significant constraints on the CPL parameters but is weak for those of the other models. Finally, we show that the use of the SL measurements in galaxy clusters is a promising and powerful technique to constrain cosmological models. The advantage of this method is that cosmological parameters are estimated by modeling the SL features for each underlying cosmology. These estimations could be further improved by SL constraints coming from other galaxy clusters
Short-Term Forecasting Models for Photovoltaic Plants: Analytical versus Soft-Computing Techniques
Monteiro, Claudio; Fernandez-Jimenez, L. Alfredo; Ramirez-Rosado, Ignacio J.; Muñoz-Jimenez, Andres; Lara-Santillan, Pedro M.
2013-01-01
We present and compare two short-term statistical forecasting models for hourly average electric power production forecasts of photovoltaic (PV) plants: the analytical PV power forecasting model (APVF) and the multiplayer perceptron PV forecasting model (MPVF). Both models use forecasts from numerical weather prediction (NWP) tools at the location of the PV plant as well as the past recorded values of PV hourly electric power production. The APVF model consists of an original modeling for adj...
Kerst, Stijn; Shyrokau, Barys; Holweg, Edward
2018-05-01
This paper proposes a novel semi-analytical bearing model addressing flexibility of the bearing outer race structure. It furthermore presents the application of this model in a bearing load condition monitoring approach. The bearing model is developed as current computational low cost bearing models fail to provide an accurate description of the more and more common flexible size and weight optimized bearing designs due to their assumptions of rigidity. In the proposed bearing model raceway flexibility is described by the use of static deformation shapes. The excitation of the deformation shapes is calculated based on the modelled rolling element loads and a Fourier series based compliance approximation. The resulting model is computational low cost and provides an accurate description of the rolling element loads for flexible outer raceway structures. The latter is validated by a simulation-based comparison study with a well-established bearing simulation software tool. An experimental study finally shows the potential of the proposed model in a bearing load monitoring approach.
Vsekhsvyatskaya, I. S.; Evstratova, E. A.; Kalinin, Yu. K.; Romanchuk, A. A.
1989-08-01
A new analytical model is proposed for the distribution of variations of the relative electron-density contrast of large-scale ionospheric inhomogeneities. The model is characterized by other-than-zero skewness and kurtosis. It is shown that the model is applicable in the interval of horizontal dimensions of inhomogeneities from hundreds to thousands of kilometers.
Behn, Maximilian; Tapken, Ulf; Puttkammer, Peter; Hagmeijer, Rob; Thouault, Nicolas
2016-01-01
The present study is dealing with the analytical modelling of sound transmission through turbomachinery stators. Two-dimensional cascade models are applied in combination with a newly proposed impedance model to account for the effect of flow deflection on the propagation of acoustic modes in
The SFR-M∗ main sequence archetypal star-formation history and analytical models
Ciesla, L.; Elbaz, D.; Fensch, J.
2017-12-01
The star-formation history (SFH) of galaxies is a key assumption to derive their physical properties and can lead to strong biases. In this work, we derive the SFH of main sequence (MS) galaxies and show how the peak SFH of a galaxy depends on its seed mass at, for example, z = 5. This seed mass reflects the galaxy's underlying dark matter (DM) halo environment. We show that, following the MS, galaxies undergo a drastic slow down of their stellar mass growth after reaching the peak of their SFH. According to abundance matching, these masses correspond to hot and massive DM halos which state could result in less efficient gas inflows on the galaxies and thus could be the origin of limited stellar mass growth. As a result, we show that galaxies, still on the MS, can enter the passive region of the UVJ diagram while still forming stars. The best fit to the MS SFH is provided by a right skew peak function for which we provide parameters depending on the seed mass of the galaxy. The ability of the classical analytical SFHs to retrieve the star-formation rate (SFR) of galaxies from spectral energy distribution (SED) fitting is studied. Due to mathematical limitations, the exponentially declining and delayed SFH struggle to model high SFR, which starts to be problematic at z > 2. The exponentially rising and log-normal SFHs exhibit the opposite behavior with the ability to reach very high SFR, and thus model starburst galaxies, but they are not able to model low values such as those expected at low redshift for massive galaxies. By simulating galaxies SED from the MS SFH, we show that these four analytical forms recover the SFR of MS galaxies with an error dependent on the model and the redshift. They are, however, sensitive enough to probe small variations of SFR within the MS, with an error ranging from 5 to 40% depending on the SFH assumption and redshift; but all the four fail to recover the SFR of rapidly quenched galaxies. However, these SFHs lead to an artificial
Analytical Modeling of Unsteady Aluminum Depletion in Thermal Barrier Coatings
YEŞİLATA, Bülent
2014-01-01
The oxidation behavior of thermal barrier coatings (TBCs) in aircraft turbines is studied. A simple, unsteady and one-dimensional, diffusion model based on aluminum depletion from a bond-coat to form an oxide layer of Al2O3 is introduced. The model is employed for a case study with currently available experimental data. The diffusion coefficient of the depleted aluminum in the alloy, the concentration profiles at different oxidation times, and the thickness of Al-depleted region are...
Energy Technology Data Exchange (ETDEWEB)
Zhang, Zhen [School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072 (China); Xia, Changliang [School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072 (China); Tianjin Engineering Center of Electric Machine System Design and Control, Tianjin 300387 (China); Yan, Yan, E-mail: yanyan@tju.edu.cn [School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072 (China); Geng, Qiang [Tianjin Engineering Center of Electric Machine System Design and Control, Tianjin 300387 (China); Shi, Tingna [School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072 (China)
2017-08-01
Highlights: • A hybrid analytical model is developed for field calculation of multilayer IPM machines. • The rotor magnetic field is calculated by the magnetic equivalent circuit method. • The field in the stator and air-gap is calculated by subdomain technique. • The magnetic scalar potential on rotor surface is modeled as trapezoidal distribution. - Abstract: Due to the complicated rotor structure and nonlinear saturation of rotor bridges, it is difficult to build a fast and accurate analytical field calculation model for multilayer interior permanent magnet (IPM) machines. In this paper, a hybrid analytical model suitable for the open-circuit field calculation of multilayer IPM machines is proposed by coupling the magnetic equivalent circuit (MEC) method and the subdomain technique. In the proposed analytical model, the rotor magnetic field is calculated by the MEC method based on the Kirchhoff’s law, while the field in the stator slot, slot opening and air-gap is calculated by subdomain technique based on the Maxwell’s equation. To solve the whole field distribution of the multilayer IPM machines, the coupled boundary conditions on the rotor surface are deduced for the coupling of the rotor MEC and the analytical field distribution of the stator slot, slot opening and air-gap. The hybrid analytical model can be used to calculate the open-circuit air-gap field distribution, back electromotive force (EMF) and cogging torque of multilayer IPM machines. Compared with finite element analysis (FEA), it has the advantages of faster modeling, less computation source occupying and shorter time consuming, and meanwhile achieves the approximate accuracy. The analytical model is helpful and applicable for the open-circuit field calculation of multilayer IPM machines with any size and pole/slot number combination.
The role of analytical models: Issues and frontiers
International Nuclear Information System (INIS)
Blair, P.
1991-03-01
A number of modeling attempts to analyze the implications of increasing competition in the electric power industry appeared in the early 1970s and occasionally throughout the early 1980s. Most of these of these analyses, however, considered only modest mechanisms to facilitate increased bulk power transactions between utility systems. More fundamental changes in market structure, such as the existence of independent power producers or wheeling transactions between customers and utility producers, were not considered. More recently in the course of the policy debate over increasing competition, a number of models have been used to analyze altemative scenarios of industry structure and regulation. In this Energy Modeling Forum (EMF) exercise, we attempted to challenge existing modeling frameworks beyond their original design capabilities. We tried to interpret altemative scenarios or other means of increasing competition in the electric power industry in the terms of existing modeling frameworks, to gain perspective using such models on how the different market players would interact, and to predict how electricity prices and other indicators of industry behavior might evolve under the altemative scenarios
Human performance modeling for system of systems analytics :soldier fatigue.
Energy Technology Data Exchange (ETDEWEB)
Lawton, Craig R.; Campbell, James E.; Miller, Dwight Peter
2005-10-01
The military has identified Human Performance Modeling (HPM) as a significant requirement and challenge of future systems modeling and analysis initiatives as can be seen in the Department of Defense's (DoD) Defense Modeling and Simulation Office's (DMSO) Master Plan (DoD 5000.59-P 1995). To this goal, the military is currently spending millions of dollars on programs devoted to HPM in various military contexts. Examples include the Human Performance Modeling Integration (HPMI) program within the Air Force Research Laboratory, which focuses on integrating HPMs with constructive models of systems (e.g. cockpit simulations) and the Navy's Human Performance Center (HPC) established in September 2003. Nearly all of these initiatives focus on the interface between humans and a single system. This is insufficient in the era of highly complex network centric SoS. This report presents research and development in the area of HPM in a system-of-systems (SoS). Specifically, this report addresses modeling soldier fatigue and the potential impacts soldier fatigue can have on SoS performance.
Analytical models approximating individual processes: a validation method.
Favier, C; Degallier, N; Menkès, C E
2010-12-01
Upscaling population models from fine to coarse resolutions, in space, time and/or level of description, allows the derivation of fast and tractable models based on a thorough knowledge of individual processes. The validity of such approximations is generally tested only on a limited range of parameter sets. A more general validation test, over a range of parameters, is proposed; this would estimate the error induced by the approximation, using the original model's stochastic variability as a reference. This method is illustrated by three examples taken from the field of epidemics transmitted by vectors that bite in a temporally cyclical pattern, that illustrate the use of the method: to estimate if an approximation over- or under-fits the original model; to invalidate an approximation; to rank possible approximations for their qualities. As a result, the application of the validation method to this field emphasizes the need to account for the vectors' biology in epidemic prediction models and to validate these against finer scale models. Copyright © 2010 Elsevier Inc. All rights reserved.
Nonlinear mathematical modeling of vibrating motion of nanomechanical cantilever active probe
Directory of Open Access Journals (Sweden)
Reza Ghaderi
Full Text Available Nonlinear vibration response of nanomechanical cantilever (NMC active probes in atomic force microscope (AFM application has been studied in the amplitude mode. Piezoelectric layer is placed piecewise and as an actuator on NMC. Continuous beam model has been chosen for analysis with regard to the geometric discontinuities of piezoelectric layer attachment and NMC's cross section. The force between the tip and the sample surface is modeled using Leonard-Jones potential. Assuming that cantilever is inclined to the sample surface, the effect of nonlinear force on NMC is considered as a shearing force and the concentrated bending moment is regarded at the end. Nonlinear frequency response of NMC is obtained close to the sample surface using the dynamic modeling. It is then become clear that the distance and angle of NMC, the probe length, and the geometric dimensions of piezoelectric layer can affect frequency response bending of the curve.
Kirby, R.
2009-08-01
Identifying an appropriate method for modelling automotive dissipative silencers normally requires one to choose between analytic and numerical methods. It is common in the literature to justify the choice of an analytic method based on the assumption that equivalent numerical techniques are more computationally expensive. The validity of this assumption is investigated here, and the relative speed and accuracy of two analytic methods are compared to two numerical methods for a uniform dissipative silencer that contains a bulk reacting porous material separated from a mean gas flow by a perforated pipe. The numerical methods are developed here with a view to speeding up transmission loss computation, and are based on a mode matching scheme and a hybrid finite element method. The results presented demonstrate excellent agreement between the analytic and numerical models provided a sufficient number of propagating acoustic modes are retained. However, the numerical mode matching method is shown to be the fastest method, significantly outperforming an equivalent analytic technique. Moreover, the hybrid finite element method is demonstrated to be as fast as the analytic technique. Accordingly, both numerical techniques deliver fast and accurate predictions and are capable of outperforming equivalent analytic methods for automotive dissipative silencers.
A Semi-Analytical Model for Dispersion Modelling Studies in the Atmospheric Boundary Layer
Gupta, A.; Sharan, M.
2017-12-01
The severe impact of harmful air pollutants has always been a cause of concern for a wide variety of air quality analysis. The analytical models based on the solution of the advection-diffusion equation have been the first and remain the convenient way for modeling air pollutant dispersion as it is easy to handle the dispersion parameters and related physics in it. A mathematical model describing the crosswind integrated concentration is presented. The analytical solution to the resulting advection-diffusion equation is limited to a constant and simple profiles of eddy diffusivity and wind speed. In practice, the wind speed depends on the vertical height above the ground and eddy diffusivity profiles on the downwind distance from the source as well as the vertical height. In the present model, a method of eigen-function expansion is used to solve the resulting partial differential equation with the appropriate boundary conditions. This leads to a system of first order ordinary differential equations with a coefficient matrix depending on the downwind distance. The solution of this system, in general, can be expressed in terms of Peano-baker series which is not easy to compute, particularly when the coefficient matrix becomes non-commutative (Martin et al., 1967). An approach based on Taylor's series expansion is introduced to find the numerical solution of first order system. The method is applied to various profiles of wind speed and eddy diffusivities. The solution computed from the proposed methodology is found to be efficient and accurate in comparison to those available in the literature. The performance of the model is evaluated with the diffusion datasets from Copenhagen (Gryning et al., 1987) and Hanford (Doran et al., 1985). In addition, the proposed method is used to deduce three dimensional concentrations by considering the Gaussian distribution in crosswind direction, which is also evaluated with diffusion data corresponding to a continuous point source.
International Nuclear Information System (INIS)
Mikhailovskii, A.B.; Shirokov, M.S.; Konovalov, S.V.; Tsypin, V.S.
2005-01-01
Transport threshold models of neoclassical tearing modes in tokamaks are investigated analytically. An analysis is made of the competition between strong transverse heat transport, on the one hand, and longitudinal heat transport, longitudinal heat convection, longitudinal inertial transport, and rotational transport, on the other hand, which leads to the establishment of the perturbed temperature profile in magnetic islands. It is shown that, in all these cases, the temperature profile can be found analytically by using rigorous solutions to the heat conduction equation in the near and far regions of a chain of magnetic islands and then by matching these solutions. Analytic expressions for the temperature profile are used to calculate the contribution of the bootstrap current to the generalized Rutherford equation for the island width evolution with the aim of constructing particular transport threshold models of neoclassical tearing modes. Four transport threshold models, differing in the underlying competing mechanisms, are analyzed: collisional, convective, inertial, and rotational models. The collisional model constructed analytically is shown to coincide exactly with that calculated numerically; the reason is that the analytical temperature profile turns out to be the same as the numerical profile. The results obtained can be useful in developing the next generation of general threshold models. The first steps toward such models have already been made
Directory of Open Access Journals (Sweden)
Jian Lu
2011-08-01
Full Text Available Multilayered microresonators commonly use sensitive coating or piezoelectric layers for detection of mass and gas. Most of these microresonators have a variable cross-section that complicates the prediction of their fundamental resonant frequency (generally of the bending mode through conventional analytical models. In this paper, we present an analytical model to estimate the first resonant frequency and deflection curve of single-clamped multilayered microresonators with variable cross-section. The analytical model is obtained using the Rayleigh and Macaulay methods, as well as the Euler-Bernoulli beam theory. Our model is applied to two multilayered microresonators with piezoelectric excitation reported in the literature. Both microresonators are composed by layers of seven different materials. The results of our analytical model agree very well with those obtained from finite element models (FEMs and experimental data. Our analytical model can be used to determine the suitable dimensions of the microresonator’s layers in order to obtain a microresonator that operates at a resonant frequency necessary for a particular application.
An analytical model for hydraulic fracturing in shallow bedrock formations.
dos Santos, José Sérgio; Ballestero, Thomas Paul; Pitombeira, Ernesto da Silva
2011-01-01
A theoretical method is proposed to estimate post-fracturing fracture size and transmissivity, and as a test of the methodology, data collected from two wells were used for verification. This method can be employed before hydrofracturing in order to obtain estimates of the potential hydraulic benefits of hydraulic fracturing. Five different pumping test analysis methods were used to evaluate the well hydraulic data. The most effective methods were the Papadopulos-Cooper model (1967), which includes wellbore storage effects, and the Gringarten-Ramey model (1974), known as the single horizontal fracture model. The hydraulic parameters resulting from fitting these models to the field data revealed that as a result of hydraulic fracturing, the transmissivity increased more than 46 times in one well and increased 285 times in the other well. The model developed by dos Santos (2008), which considers horizontal radial fracture propagation from the hydraulically fractured well, was used to estimate potential fracture geometry after hydrofracturing. For the two studied wells, their fractures could have propagated to distances of almost 175 m or more and developed maximum apertures of about 2.20 mm and hydraulic apertures close to 0.30 mm. Fracturing at this site appears to have expanded and propagated existing fractures and not created new fractures. Hydraulic apertures calculated from pumping test analyses closely matched the results obtained from the hydraulic fracturing model. As a result of this model, post-fracturing geometry and resulting post-fracturing well yield can be estimated before the actual hydrofracturing. Copyright © 2010 The Author(s). Journal compilation © 2010 National Ground Water Association.
Semi-analytical wave functions in relativistic average atom model for high-temperature plasmas
International Nuclear Information System (INIS)
Guo Yonghui; Duan Yaoyong; Kuai Bin
2007-01-01
The semi-analytical method is utilized for solving a relativistic average atom model for high-temperature plasmas. Semi-analytical wave function and the corresponding energy eigenvalue, containing only a numerical factor, are obtained by fitting the potential function in the average atom into hydrogen-like one. The full equations for the model are enumerated, and more attentions are paid upon the detailed procedures including the numerical techniques and computer code design. When the temperature of plasmas is comparatively high, the semi-analytical results agree quite well with those obtained by using a full numerical method for the same model and with those calculated by just a little different physical models, and the result's accuracy and computation efficiency are worthy of note. The drawbacks for this model are also analyzed. (authors)
An Analytical Model for Fatigue Life Prediction Based on Fracture Mechanics and Crack Closure
DEFF Research Database (Denmark)
Ibsø, Jan Behrend; Agerskov, Henning
1996-01-01
test specimens are compared with fatigue life predictions using a fracture mechanics approach. In the calculation of the fatigue life, the influence of the welding residual stresses and crack closure on the fatigue crack growth is considered. A description of the crack closure model for analytical...... of the analytical fatigue lives. Both the analytical and experimental results obtained show that the Miner rule may give quite unconservative predictions of the fatigue life for the types of stochastic loading studied....... determination of the fatigue life is included. Furthermore, the results obtained in studies of the various parameters that have an influence on the fatigue life, are given. A very good agreement between experimental and analytical results is obtained, when the crack closure model is used in determination...
Modelling of packet traffic with matrix analytic methods
DEFF Research Database (Denmark)
Andersen, Allan T.
1995-01-01
vot reveal any adverse behaviour. In fact the observed traffic seemed very close to what would be expected from Poisson traffic. The Changeover/Changeback procedure in SS7, which is used to redirect traffic in case of link failure, has been analyzed. The transient behaviour during a Changeover...... scenario was modelled using Markovian models. The Ordinary Differential Equations arising from these models were solved numerically. The results obtained seemed very similar to those obtained using a different method in previous work by Akinpelu & Skoog 1985. Recent measurement studies of packet traffic...... is found by noting the close relationship with the expressions for the corresponding infinite queue. For the special case of a batch Poisson arrival process this observation makes it possible to express the queue length at an arbitrary in terms of the corresponding queue lengths for the infinite case....
An Analytic Model Approach to the Frequency of Exoplanets
Traub, Wesley A.
2016-10-01
The underlying population of exoplanets around stars in the Kepler sample can be inferred by a simulation that includes binning the Kepler planets in radius and period, invoking an empirical noise model, assuming a model exoplanet distribution function, randomly assigning planets to each of the Kepler target stars, asking whether each planet's transit signal could be detected by Kepler, binning the resulting simulated detections, comparing the simulations with the observed data sample, and iterating on the model parameters until a satisfactory fit is obtained. The process is designed to simulate the Kepler observing procedure. The key assumption is that the distribution function is the product of separable functions of period and radius. Any additional suspected biases in the sample can be handled by adjusting the noise model or selective editing of the range of input planets. An advantage of this overall procedure is that it is a forward calculation designed to simulate the observed data, subject to a presumed underlying population distribution, minimizing the effect of bin-to-bin fluctuations. Another advantage is that the resulting distribution function can be extended to values of period and radius that go beyond the sample space, including, for example, application to estimating eta-sub-Earth, and also estimating the expected science yields of future direct-imaging exoplanet missions such as WFIRST-AFTA.
SPOTROD: Semi-analytic model for transits of spotted stars
Béky, Bence
2014-11-01
SPOTROD is a model for planetary transits of stars with an arbitrary limb darkening law and a number of homogeneous, circular spots on their surface. It facilitates analysis of anomalies due to starspot eclipses, and is a free, open source implementation written in C with a Python API.
a new analytical modeling method for photovoltaic solar cells based
African Journals Online (AJOL)
Zieba Falama R, Dadjé A, Djongyang N and Doka S.Y
2016-05-01
May 1, 2016 ... network. However, its exploitation requires a conception and implantation of a production system which also require a good sizing in order to avoid losses or lack of energy. The evaluation of the maximum power produced by a PV generator is very important to size a. PV system. Several models have been ...
Analytical results for the Sznajd model of opinion formation
Czech Academy of Sciences Publication Activity Database
Slanina, František; Lavička, H.
2003-01-01
Roč. 35, - (2003), s. 279-288 ISSN 1434-6028 R&D Projects: GA ČR GA202/01/1091 Institutional research plan: CEZ:AV0Z1010914 Keywords : agent models * sociophysics Subject RIV: BE - Theoretical Physics Impact factor: 1.457, year: 2003
Analytic properties of the Ruelle ζ-function for mean field models of phase transition
International Nuclear Information System (INIS)
Hallerberg, Sarah; Just, Wolfram; Radons, Guenter
2005-01-01
We evaluate by analytical means the Ruelle ζ-function for a spin model with global coupling. The implications of the ferromagnetic phase transitions for the analytical properties of the ζ-function are discussed in detail. In the paramagnetic phase the ζ-function develops a single branch point. In the low-temperature regime two branch points appear which correspond to the ferromagnetic state and the metastable state. The results are typical for any Ginsburg-Landau-type phase transition
Characterisation and analytical modeling of GaN HEMT-based varactor diodes
Hamdoun , Abdelaziz; Roy , L.; Himdi , Mohamed; Lafond , Olivier
2015-01-01
International audience; Varactor diodes fabricated in 0.5 and 0.15 μm GaN HEMT (high-electron-mobility transistor) processes are modelled. The devices were characterised via DC and RF small-signal measurements up to 20 GHz, and fitted to a simple physical equivalent circuit. Approximate analytical expressions containing empirical coefficients are introduced for the voltage dependency of capacitance and series resistance. The analytical solutions agree remarkably well with the experimentally e...
Decision-analytic modeling studies: An overview for clinicians using multiple myeloma as an example.
Rochau, U; Jahn, B; Qerimi, V; Burger, E A; Kurzthaler, C; Kluibenschaedl, M; Willenbacher, E; Gastl, G; Willenbacher, W; Siebert, U
2015-05-01
The purpose of this study was to provide a clinician-friendly overview of decision-analytic models evaluating different treatment strategies for multiple myeloma (MM). We performed a systematic literature search to identify studies evaluating MM treatment strategies using mathematical decision-analytic models. We included studies that were published as full-text articles in English, and assessed relevant clinical endpoints, and summarized methodological characteristics (e.g., modeling approaches, simulation techniques, health outcomes, perspectives). Eleven decision-analytic modeling studies met our inclusion criteria. Five different modeling approaches were adopted: decision-tree modeling, Markov state-transition modeling, discrete event simulation, partitioned-survival analysis and area-under-the-curve modeling. Health outcomes included survival, number-needed-to-treat, life expectancy, and quality-adjusted life years. Evaluated treatment strategies included novel agent-based combination therapies, stem cell transplantation and supportive measures. Overall, our review provides a comprehensive summary of modeling studies assessing treatment of MM and highlights decision-analytic modeling as an important tool for health policy decision making. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Ajeng Diasputri
2016-07-01
Full Text Available Penelitian ini bertujuan untuk mengetahui pengaruh penggunaan model pembelajaran Probing-Prompting Berbantuan Lembar Kerja Berstruktur terhadap hasil be/ajar siswa di suatu sekolah pada materi Hidrokarbon dan Minyak Bumi. Pengambilan sampel dilakukan dengan menggunakan teknik Purposive Sampling. Pada kelas eksperimen digunakan model pembelajaran probing-prompting berbantuan lembar kerja berstruktur, sedangkan kelas kontrol menggunakan metode konvesional. Setelah diberi perlakuan yang berbeda dan dilakukan post test dapat diketahui bahwa hasil be/ajar siswa kelas ekperimen lebih baik dibandingkan hasil be/ajar siswa kelas kontrol, yaitu masing-masing 77 dan 70. Berdasarkan uji perbedaan rata-rata hasil be/ajar, diperoleh thitung(4,074> trabe1(1,669, maka dapat dikatakan bahwa rata-rata hasil be/ajar kelompok eksperimen lebih baik dari kelompok kontrol. Pada uji ketuntasan be/ajar, persentase ketuntasan kelas eksperimen mencapai 91, 18% dan kelas kontrol mencapai 59,38%. Uji korelasi memperoleh harga koefisien biserial sebesar 0,5638. Dari seluruh hasil penelitian ini, dapat disimpulkan bahwa model pembelajaran probing-prompting berbantuan LKB berpengaruh terhadap hasil be/ajar siswa pada materi pokok Hidrokarbon dan Minyak bumi dengan memberikan kontribusi sebesar 32%.This study aimed to know the influence of the use of a learning model Probing-prompting assisted by structured worksheet on learning outcomes in an high school especially in the Hydrocarbon and Petroleum. Sampling is done by using purposive sampling technique. In the experimental class, learning used Probing-prompting assisted by structured worksheet, while in classroom control used conventional methods. After being given a different treatment and after post test was done, it can be concluded that students' learning outcomes in class experiment is better than the control class, respectively 77 and 70. Based on the analysis of difference average learning outcomes, it obtained fcounr
Fuel assembly bow: analytical modeling and resulting design improvements
International Nuclear Information System (INIS)
Stabel, J.; Huebsch, H.P.
1995-01-01
The bowing of fuel assemblies may result in a contact between neighbouring fuel assemblies and in connection with a vibration to a resulting wear or even perforation at the corners of the spacer grids of neighbouring assemblies. Such events allowed reinsertion of a few fuel assemblies in Germany only after spacer repair. In order to identify the most sensitive parameters causing the observed bowing of fuel assemblies a new computer model was develop which takes into a account the highly nonlinear behaviour of the interaction between fuel rods and spacers. As a result of the studies performed with this model, design improvements such as a more rigid connection between guide thimbles and spacer grids, could be defined. First experiences with this improved design show significantly better fuel behaviour. (author). 5 figs., 1 tabs
An Analytic Model Of Thermal Drift In Piezoresistive Microcantilever Sensors
Energy Technology Data Exchange (ETDEWEB)
Loui, A; Elhadj, S; Sirbuly, D J; McCall, S K; Hart, B R; Ratto, T V
2009-08-26
A closed form semi-empirical model has been developed to understand the physical origins of thermal drift in piezoresistive microcantilever sensors. The two-component model describes both the effects of temperature-related bending and heat dissipation on the piezoresistance. The temperature-related bending component is based on the Euler-Bernoulli theory of elastic deformation applied to a multilayer cantilever. The heat dissipation component is based on energy conservation per unit time for a piezoresistive cantilever in a Wheatstone bridge circuit, representing a balance between electrical power input and heat dissipation into the environment. Conduction and convection are found to be the primary mechanisms of heat transfer, and the dependence of these effects on the thermal conductivity, temperature, and flow rate of the gaseous environment is described. The thermal boundary layer value which defines the length scale of the heat dissipation phenomenon is treated as an empirical fitting parameter. Using the model, it is found that the cantilever heat dissipation is unaffected by the presence of a thin polymer coating, therefore the residual thermal drift in the differential response of a coated and uncoated cantilever is the result of non-identical temperature-related bending. Differential response data shows that residual drift is eliminated under isothermal laboratory conditions but not the unregulated and variable conditions that exist in the outdoor environment (i.e., the field). The two-component model is then validated by simulating the thermal drifts of an uncoated and a coated piezoresistive cantilever under field conditions over a 24 hour period using only meteorological data as input.
An Analytic Model for DoD Divestments
2015-04-30
double counting, especially if more than one or a complex intervention is being assessed. Based on models of social investment, social entrepreneurship ...Background Organizations invest and divest resources to prepare for the future and respond to events or conditions in the relevant social , political...hobby, speculation) have various tendencies to “stick to the status quo” and not divest.15 Leveraging Other Fields: Social Return on Investment
Analytical model describes ion conduction in fuel cell membranes
Herbst, Daniel; Tse, Steve; Witten, Thomas
2014-03-01
Many fuel cell designs employ polyelectrolyte membranes, but little is known about how to tune the parameters (water level, morphology, etc.) to maximize ion conductivity. We came up with a simple model based on a random, discrete water distribution and ion confinement due to neighboring polymer. The results quantitatively agree with molecular dynamics (MD) simulations and explain experimental observations. We find that when the ratio of water volume to polymer volume, Vw /Vp , is small, the predicted ion self-diffusion coefficient scales roughly as Dw T√{Vw /Vp } exp(- ⋯Vp /Vw) , where Dw T is the limiting value in pure water at temperature T . At high water levels the model also agrees with MD simulation, plateauing to Dw T . The model predicts a maximum conductivity at a water level higher than is typically used, and that it would be beneficial to increase water retention even at the expense of lower ion concentration. Also, membranes would conduct better if they phase-separated into water-rich and polymer-rich regions. US ARMY MURI #W911NF-10-1-0520.
Directory of Open Access Journals (Sweden)
Rita Diartini
2017-06-01
Full Text Available The purpose of this research is to know the effect of learning probing prompting assisted flash card media to the learning outcomes of study of IPS integrated second semester class VII MTs Muhammadiyah Metro academic year 2016/2017.The population in this study is the students of class VII MTs Muhammadiyah Metro academic year 2016/2017 which amounted to 48 students. The sample used is class VIIB MTs Muhammadiyah Metro which amounts to 24 students as experiment class, while class VIIA become control class. This study aims to determine whether there is influence of the use of learning with Probing Prompting Helped Flash Card Media to the results of learning IPS integrated with the formula of simple linear regression. From the data analysis of the results of the study using simple linear regression formula with a significant level of 5% obtained tcount = 3.85 while ttable = 1.72 shows t count > ttable, so the hypothesis accepted, that there is a significant influence from the use of probing prompting model assisted flash card media on the learning outcomes of study of IPS integrated second semester class VII MTs Muhammadiyah Metro academic year 2016/2017. Keywords : Flash card, Learning outcomes, Probing prompting
A semi analytical model for short range dispersion from ground sources
Gavze, Ehud; Reichman, Rivka; Fattal, Eyal
2014-05-01
A semi-analytical model for dispersion of passive scalars from ground sources up to distances of a few hundred meters is presented. Analytical, or semi-analytical models are useful as they are simple to use and require only a short computation time, compared, for example, to Lagrangian Stochastic Models. As such they are valuable in cases where repeated computations of the concentration field is required, as for example in risk assessments and in the inverse problem of source determination. Among the analytical models the most widely used are the Gaussian models which assume both a uniform wind field and homogeneous turbulence. These assumptions are not valid when ground source is involved since both the wind and the turbulence depend on height. The model proposed here is free of these two assumptions. The formulation of the vertical dispersion is based on approximating the vertical profiles of the wind and the the vertical diffusion coefficient as power laws. One advantage of this approach is that it allows for non Gaussian vertical profiles of the concentration which better fit the experimental data. For the lateral dispersion the model still assumes a Gaussian form. A system of equations was developed to compute the cloud width, taking into account the non-homogeneity of the wind and the turbulence in the vertical direction. The model was tested against two field experiments. Comparison with a Gaussian model showed that it performed much better in predicting both the integrated cross wind ground concentration and the cloud width.
A contact resistance model for scanning probe phase-change memory
International Nuclear Information System (INIS)
Wang, Lei; Ying, Jin; Wei Yang, Guo; Wright, David; Aziz, Mustafa
2014-01-01
A novel mechanical model was proposed to calculate the contact resistance at tip and capping layer interface for scanning probe phase-change memory applications. The resulting I–V curve calculated from this model that combines Hertzian contact theory with the Schottky diode effect has exhibited a good agreement with the experimental measurements under the same system architecture. The role of contact resistance on the write efficacy of scanning probe phase-change memory was also evaluated by introducing the calculated contact resistance into the previous electrothermal simulations for cases of writing crystalline bits in amorphous starting phase and writing amorphous bits in crystalline starting phase. The consequent written marks and I–V curve show a closer match with the experimental observation compared to the case without including contact resistance. (technical note)
Frequency-domain modelling of gain in pump-probe experiment by an inhomogeneous medium
Kim, Minkyung; Oh, Sang Soon; Hess, Ortwin; Rho, Junsuk
2018-02-01
Introduction of a gain medium in lossy plasmonic metamaterials reduces and compensates losses or even amplifies an incident light often with nonlinear optical effect. Here, optical gain in a pump-probe experimental setup is effectively calculated in the frequency-domain by approximating a gain material as an inhomogeneous medium. Spatially varying local field amplitudes of the pump and probe beams are included in the model to reproduce the inhomogeneous gain effect, in which population inversion occurs most strongly near the surface and decays along the propagation direction. We demonstrate that transmission spectra calculated by this method agree well with finite-difference time-domain simulation results. This simplified approach of gain modelling offers an easy and reliable way to analyze wave propagation in a gain medium without nonlinear time-domain calculation.
Directory of Open Access Journals (Sweden)
D. A. Robinson
1998-01-01
Full Text Available Capacitance probes are a fast, safe and relatively inexpensive means of measuring the relative permittivity of soils, which can then be used to estimate soil water content. Initial experiments with capacitance probes used empirical calibrations between the frequency response of the instrument and soil water content. This has the disadvantage that the calibrations are instrument-dependent. A twofold calibration strategy is described in this paper; the instrument frequency is turned into relative permittivity (dielectric constant which can then be calibrated against soil water content. This approach offers the advantages of making the second calibration, from soil permittivity to soil water content. instrument-independent and allows comparison with other dielectric methods, such as time domain reflectometry. A physically based model, used to calibrate capacitance probes in terms of relative permittivity (εr is presented. The model, which was developed from circuit analysis, predicts, successfully, the frequency response of the instrument in liquids with different relative permittivities, using only measurements in air and water. lt was used successfully to calibrate 10 prototype surface capacitance insertion probes (SCIPS and a depth capacitance probe. The findings demonstrate that the geometric properties of the instrument electrodes were an important parameter in the model, the value of which could be fixed through measurement. The relationship between apparent soil permittivity and volumetric water content has been the subject of much research in the last 30 years. Two lines of investigation have developed, time domain reflectometry (TDR and capacitance. Both methods claim to measure relative permittivity and should therefore be comparable. This paper demonstrates that the IH capacitance probe overestimates relative permittivity as the ionic conductivity of the medium increases. Electrically conducting ionic solutions were used to test the
Analytical solution for two-phase flow in a wellbore using the drift-flux model
Energy Technology Data Exchange (ETDEWEB)
Pan, L.; Webb, S.W.; Oldenburg, C.M.
2011-11-01
This paper presents analytical solutions for steady-state, compressible two-phase flow through a wellbore under isothermal conditions using the drift flux conceptual model. Although only applicable to highly idealized systems, the analytical solutions are useful for verifying numerical simulation capabilities that can handle much more complicated systems, and can be used in their own right for gaining insight about two-phase flow processes in wells. The analytical solutions are obtained by solving the mixture momentum equation of steady-state, two-phase flow with an assumption that the two phases are immiscible. These analytical solutions describe the steady-state behavior of two-phase flow in the wellbore, including profiles of phase saturation, phase velocities, and pressure gradients, as affected by the total mass flow rate, phase mass fraction, and drift velocity (i.e., the slip between two phases). Close matching between the analytical solutions and numerical solutions for a hypothetical CO{sub 2} leakage problem as well as to field data from a CO{sub 2} production well indicates that the analytical solution is capable of capturing the major features of steady-state two-phase flow through an open wellbore, and that the related assumptions and simplifications are justified for many actual systems. In addition, we demonstrate the utility of the analytical solution to evaluate how the bottomhole pressure in a well in which CO{sub 2} is leaking upward responds to the mass flow rate of CO{sub 2}-water mixture.
Fitting three-level meta-analytic models in R: A step-by-step tutorial
Directory of Open Access Journals (Sweden)
Assink, Mark
2016-10-01
Full Text Available Applying a multilevel approach to meta-analysis is a strong method for dealing with dependency of effect sizes. However, this method is relatively unknown among researchers and, to date, has not been widely used in meta-analytic research. Therefore, the purpose of this tutorial was to show how a three-level random effects model can be applied to meta-analytic models in R using the rma.mv function of the metafor package. This application is illustrated by taking the reader through a step-by-step guide to the multilevel analyses comprising the steps of (1 organizing a data file; (2 setting up the R environment; (3 calculating an overall effect; (4 examining heterogeneity of within-study variance and between-study variance; (5 performing categorical and continuous moderator analyses; and (6 examining a multiple moderator model. By example, the authors demonstrate how the multilevel approach can be applied to meta-analytically examining the association between mental health disorders of juveniles and juvenile offender recidivism. In our opinion, the rma.mv function of the metafor package provides an easy and flexible way of applying a multi-level structure to meta-analytic models in R. Further, the multilevel meta-analytic models can be easily extended so that the potential moderating influence of variables can be examined.
Analytical modelling for predicting the sound field of planar acoustic metasurface
Zhou, Jie; Zhang, Xin; Fang, Yi
2018-01-01
An analytical model is built to predict the acoustic fields of acoustic metasurfaces. The acoustic fields are investigated for a Gaussian sound beam incident on the acoustic metasurfaces. The Gaussian sound beam is decomposed into a set of discrete elementary plane waves. The diffraction caused by the acoustic metasurfaces can be obtained using this analytical model, which is validated with the numerical simulations for the different incident angles of the Gaussian sound beam. This model overcomes the limitation of the method based on the generalised Snell's law which can only predict the direction of a specific diffracted order. Actually, this analytical model can be also used to predict the sound fields of acoustic metasurfaces under any incident sound if its Fourier transforms exist. This conclusion is demonstrated by studying the sound field for a point sound source incident on the acoustic metasurface. The acoustic admittances of acoustic metasurfaces are required in the calculation of the analytical model. Therefore, a numerical method for obtaining the effective acoustic admittances is proposed for the structurally complex metasurfaces without the analytical expressions of material properties, such as equivalent density and sound speed.
New global loss model of energetic and relativistic electrons based on Van Allen Probes measurements
Ksenia Orlova; Yuri Shprits; Maria Spasojevic
2016-01-01
The Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument on the Van Allen Probes provides a vast quantity of fully resolved wave measurements below L = 5.5, a critical region for radiation belt acceleration and loss. EMFISIS data show that plasmaspheric hiss waves can be observed at frequencies as low as 20 Hz and provide three-component magnetic field measurements that can be directly used for electron scattering calculations. Updated models of hiss proper...
Semi-analytical modelling of positive corona discharge in air
Pontiga, Francisco; Yanallah, Khelifa; Chen, Junhong
2013-09-01
Semianalytical approximate solutions of the spatial distribution of electric field and electron and ion densities have been obtained by solving Poisson's equations and the continuity equations for the charged species along the Laplacian field lines. The need to iterate for the correct value of space charge on the corona electrode has been eliminated by using the corona current distribution over the grounded plane derived by Deutsch, which predicts a cos m θ law similar to Warburg's law. Based on the results of the approximated model, a parametric study of the influence of gas pressure, the corona wire radius, and the inter-electrode wire-plate separation has been carried out. Also, the approximate solutions of the electron number density has been combined with a simplified plasma chemistry model in order to compute the ozone density generated by the corona discharge in the presence of a gas flow. This work was supported by the Consejeria de Innovacion, Ciencia y Empresa (Junta de Andalucia) and by the Ministerio de Ciencia e Innovacion, Spain, within the European Regional Development Fund contracts FQM-4983 and FIS2011-25161.
Analytical modeling of structure-soil systems for lunar bases
Macari-Pasqualino, Jose Emir
1989-01-01
The study of the behavior of granular materials in a reduced gravity environment and under low effective stresses became a subject of great interest in the mid 1960's when NASA's Surveyor missions to the Moon began the first extraterrestrial investigation and it was found that Lunar soils exhibited properties quite unlike those on Earth. This subject gained interest during the years of the Apollo missions and more recently due to NASA's plans for future exploration and colonization of Moon and Mars. It has since been clear that a good understanding of the mechanical properties of granular materials under reduced gravity and at low effective stress levels is of paramount importance for the design and construction of surface and buried structures on these bodies. In order to achieve such an understanding it is desirable to develop a set of constitutive equations that describes the response of such materials as they are subjected to tractions and displacements. This presentation examines issues associated with conducting experiments on highly nonlinear granular materials under high and low effective stresses. The friction and dilatancy properties which affect the behavior of granular soils with low cohesion values are assessed. In order to simulate the highly nonlinear strength and stress-strain behavior of soils at low as well as high effective stresses, a versatile isotropic, pressure sensitive, third stress invariant dependent, cone-cap elasto-plastic constitutive model was proposed. The integration of the constitutive relations is performed via a fully implicit Backward Euler technique known as the Closest Point Projection Method. The model was implemented into a finite element code in order to study nonlinear boundary value problems associated with homogeneous as well as nonhomogeneous deformations at low as well as high effective stresses. The effect of gravity (self-weight) on the stress-strain-strength response of these materials is evaluated. The calibration
An Assessment Model of National Grants of University Based on Fuzzy Analytic Hierarchy Process
Directory of Open Access Journals (Sweden)
Xia Yang
2016-01-01
Full Text Available How to assess kinds of grants scientifically, effectively and regularly is an important topic for the funding workers to study. According to the national grants’ basic conditions, an assessment model is established on the basis of fuzzy analytic hierarchy process. And Finally an example is given to illustrate the scientificalness and operability of this model.
A Two-Dimensional Analytic Thermal Model for a High-Speed PMSM Magnet
CSIR Research Space (South Africa)
Grobler, AJ
2015-11-01
Full Text Available . The temperature-dependent properties of permanent magnets necessitate high-detail thermal models. This paper presents a 2-D analytical model for a HS PMSM magnet. The diffusion equation is solved where three of the PM boundaries experience convection heat flow...
Improved Analytical Model of a Permanent-Magnet Brushless DC Motor
Kumar, P.; Bauer, P.
2008-01-01
In this paper, we develop a comprehensive model of a permanent-magnet brushless DC (BLDC) motor. An analytical model for determining instantaneous air-gap field density is developed. This instantaneous field distribution can be further used to determine the cogging torque, induced back electromotive
A Bayesian Multi-Level Factor Analytic Model of Consumer Price Sensitivities across Categories
Duvvuri, Sri Devi; Gruca, Thomas S.
2010-01-01
Identifying price sensitive consumers is an important problem in marketing. We develop a Bayesian multi-level factor analytic model of the covariation among household-level price sensitivities across product categories that are substitutes. Based on a multivariate probit model of category incidence, this framework also allows the researcher to…
An analytical model for the performance of geographical multi-hop broadcast
Klein Wolterink, W.; Heijenk, G.; Berg, J.L. van den
2012-01-01
In this paper we present an analytical model accurately describing the behaviour of a multi-hop broadcast protocol. Our model covers the scenario in which a message is forwarded over a straight road and inter-node distances are distributed exponentially. Intermediate forwarders draw a small random
Analytical model for double split ring resonators with arbitrary ring width
DEFF Research Database (Denmark)
Zhurbenko, Vitaliy; Jensen, Thomas; Krozer, Viktor
2008-01-01
For the first time, the analytical model for a double split ring resonator with unequal width rings is developed. The proposed models for the resonators with equal and unequal widths are based on an impedance matrix representation and provide the prediction of performance in a wide frequency range...
Several advances in the analytic element method have been made to enhance its performance and facilitate three-dimensional ground-water flow modeling in a regional aquifer setting. First, a new public domain modular code (ModAEM) has been developed for modeling ground-water flow ...
An improved analytical model for carrier multiplication near breakdown in diodes
Hueting, Raymond Josephus Engelbart; Heringa, Anco; Boksteen, B.K.; Dutta, Satadal; Ferrara, A.; Agarwal, Vishal Vishal; Annema, Anne J.
2017-01-01
The charge carrier contributions to impact ionization and avalanche multiplication are analyzed in detail. A closed-form analytical model is derived for the ionization current before the onset of breakdown induced by both injection current components. This model shows that the ratio of both
Robin J. Tausch
2015-01-01
A theoretically based analytic model of plant growth in single species conifer communities based on the species fully occupying a site and fully using the site resources is introduced. Model derivations result in a single equation simultaneously describes changes over both, different site conditions (or resources available), and over time for each variable for each...
Analytic model utilizing the complex ABCD method for range dependency of a monostatic coherent lidar
DEFF Research Database (Denmark)
Olesen, Anders Sig; Pedersen, Anders Tegtmeier; Hanson, Steen Grüner
2014-01-01
In this work, we present an analytic model for analyzing the range and frequency dependency of a monostatic coherent lidar measuring velocities of a diffuse target. The model of the signal power spectrum includes both the contribution from the optical system as well as the contribution from the t...
Mapping the Complexities of Online Dialogue: An Analytical Modeling Technique
Directory of Open Access Journals (Sweden)
Robert Newell
2014-03-01
Full Text Available The e-Dialogue platform was developed in 2001 to explore the potential of using the Internet for engaging diverse groups of people and multiple perspectives in substantive dialogue on sustainability. The system is online, text-based, and serves as a transdisciplinary space for bringing together researchers, practitioners, policy-makers and community leaders. The Newell-Dale Conversation Modeling Technique (NDCMT was designed for in-depth analysis of e-Dialogue conversations and uses empirical methodology to minimize observer bias during analysis of a conversation transcript. NDCMT elucidates emergent ideas, identifies connections between ideas and themes, and provides a coherent synthesis and deeper understanding of the underlying patterns of online conversations. Continual application and improvement of NDCMT can lead to powerful methodologies for empirically analyzing digital discourse and better capture of innovations produced through such discourse. URN: http://nbn-resolving.de/urn:nbn:de:0114-fqs140221
Analytical modelling and experimental studies of SIS tunnel solar cells
Energy Technology Data Exchange (ETDEWEB)
Cheknane, Ali [Laboratoire de Valorisation des Energies Renouvelables et Environnements Agressifs, Universite Amar Telidji de Laghouat, BP 37G route de Ghardaia, Laghouat (03000) Algerie (Algeria)], E-mail: cheknanali@yahoo.com
2009-06-07
This paper presents an experimental and computational study of semiconductor-insulator-semiconductor (SIS) tunnel solar cells. A transparent and conductive film of thallium trioxide Tl{sub 2}O{sub 3} has been deposited by anodic oxidation onto an n-Si(1 0 0) face to realize the SIS tunnel solar cells based on Si/SiO{sub x}/Tl{sub 2}O{sub 3}. An efficiency of 8.77% has been obtained under an incident power density of 33 mW cm{sup -2} illumination condition. A PSPICE model is implemented. The calculated results show that the theoretical values are in good agreement with experimental data. Moreover, the simulation clearly demonstrates that the performance of the tested device can be significantly improved.
Analytical model for three-dimensional Mercedes-Benz water molecules
Urbic, T.
2012-01-01
We developed a statistical model which describes the thermal and volumetric properties of water-like molecules. A molecule is presented as a three-dimensional sphere with four hydrogen-bonding arms. Each water molecule interacts with its neighboring waters through a van der Waals interaction and an orientation-dependent hydrogen-bonding interaction. This model, which is largely analytical, is a variant of a model developed before for a two-dimensional Mercedes-Benz model of water. We explored...
Measurement strategy and analytic model to determine firing pin force
Lesenciuc, Ioan; Suciu, Cornel
2016-12-01
As illustrated in literature, ballistics is a branch of theoretical mechanics, which studies the construction and working principles of firearms and ammunition, their effects, as well as the motions of projectiles and bullets1. Criminalistics identification, as part of judiciary identification represents an activity aimed at finding common traits of different objects, objectives, phenomena and beings, but more importantly, traits that differentiate each of them from similar ones2-4. In judicial ballistics, in the case of rifled firearms it is relatively simple for experts to identify the used weapon from traces left on the projectile, as the rifling of the barrel leaves imprints on the bullet, which remain approximately identical even after the respective weapon is fired 100 times with the same barrel. However, in the case of smoothbore firearms, their identification becomes much more complicated. As the firing cap suffers alterations from being hit by the firing pin, determination of the force generated during impact creates the premises for determining the type of firearm used to shoot the respective cartridge. The present paper proposes a simple impact model that can be used to evaluate the force generated by the firing pin during its impact with the firing cap. The present research clearly showed that each rifle, by the combination of the three investigated parameters (impact force maximum value, its variation diagram, and impact time) leave a unique trace. Application of such a method in ballistics can create the perspectives for formulating clear conclusions that eliminate possible judicial errors in this field.
Analytical Modeling Tool for Design of Hydrocarbon Sensitive Optical Fibers
Directory of Open Access Journals (Sweden)
Khalil Al Handawi
2017-09-01
Full Text Available Pipelines are the main transportation means for oil and gas products across large distances. Due to the severe conditions they operate in, they are regularly inspected using conventional Pipeline Inspection Gages (PIGs for corrosion damage. The motivation for researching a real-time distributed monitoring solution arose to mitigate costs and provide a proactive indication of potential failures. Fiber optic sensors with polymer claddings provide a means of detecting contact with hydrocarbons. By coating the fibers with a layer of metal similar in composition to that of the parent pipeline, corrosion of this coating may be detected when the polymer cladding underneath is exposed to the surrounding hydrocarbons contained within the pipeline. A Refractive Index (RI change occurs in the polymer cladding causing a loss in intensity of a traveling light pulse due to a reduction in the fiber’s modal capacity. Intensity losses may be detected using Optical Time Domain Reflectometry (OTDR while pinpointing the spatial location of the contact via time delay calculations of the back-scattered pulses. This work presents a theoretical model for the above sensing solution to provide a design tool for the fiber optic cable in the context of hydrocarbon sensing following corrosion of an external metal coating. Results are verified against the experimental data published in the literature.
International Nuclear Information System (INIS)
Khater, Antoine; Szczesniak, Dominik
2011-01-01
An analytical model is presented for the electronic conductance in a one dimensional atomic chain across an isolated defect. The model system consists of two semi infinite lead atomic chains with the defect atom making the junction between the two leads. The calculation is based on a linear combination of atomic orbitals in the tight-binding approximation, with a single atomic one s-like orbital chosen in the present case. The matching method is used to derive analytical expressions for the scattering cross sections for the reflection and transmission processes across the defect, in the Landauer-Buttiker representation. These analytical results verify the known limits for an infinite atomic chain with no defects. The model can be applied numerically for one dimensional atomic systems supported by appropriate templates. It is also of interest since it would help establish efficient procedures for ensemble averages over a field of impurity configurations in real physical systems.
An analytically resolved model of a potato's thermal processing using Heun functions
Vargas Toro, Agustín.
2014-05-01
A potato's thermal processing model is solved analytically. The model is formulated using the equation of heat diffusion in the case of a spherical potato processed in a furnace, and assuming that the potato's thermal conductivity is radially modulated. The model is solved using the method of the Laplace transform, applying Bromwich Integral and Residue Theorem. The temperatures' profile in the potato is presented as an infinite series of Heun functions. All computations are performed with computer algebra software, specifically Maple. Using the numerical values of the thermal parameters of the potato and geometric and thermal parameters of the processing furnace, the time evolution of the temperatures in different regions inside the potato are presented analytically and graphically. The duration of thermal processing in order to achieve a specified effect on the potato is computed. It is expected that the obtained analytical results will be important in food engineering and cooking engineering.
Energy Technology Data Exchange (ETDEWEB)
Khater, Antoine; Szczesniak, Dominik [Laboratoire de Physique de l' Etat Condense UMR 6087, Universite du Maine, 72085 Le Mans (France)
2011-04-01
An analytical model is presented for the electronic conductance in a one dimensional atomic chain across an isolated defect. The model system consists of two semi infinite lead atomic chains with the defect atom making the junction between the two leads. The calculation is based on a linear combination of atomic orbitals in the tight-binding approximation, with a single atomic one s-like orbital chosen in the present case. The matching method is used to derive analytical expressions for the scattering cross sections for the reflection and transmission processes across the defect, in the Landauer-Buttiker representation. These analytical results verify the known limits for an infinite atomic chain with no defects. The model can be applied numerically for one dimensional atomic systems supported by appropriate templates. It is also of interest since it would help establish efficient procedures for ensemble averages over a field of impurity configurations in real physical systems.
A two-dimensional analytical model of vapor intrusion involving vertical heterogeneity
Yao, Yijun; Verginelli, Iason; Suuberg, Eric M.
2017-05-01
In this work, we present an analytical chlorinated vapor intrusion (CVI) model that can estimate source-to-indoor air concentration attenuation by simulating two-dimensional (2-D) vapor concentration profile in vertically heterogeneous soils overlying a homogenous vapor source. The analytical solution describing the 2-D soil gas transport was obtained by applying a modified Schwarz-Christoffel mapping method. A partial field validation showed that the developed model provides results (especially in terms of indoor emission rates) in line with the measured data from a case involving a building overlying a layered soil. In further testing, it was found that the new analytical model can very closely replicate the results of three-dimensional (3-D) numerical models at steady state in scenarios involving layered soils overlying homogenous groundwater sources. By contrast, by adopting a two-layer approach (capillary fringe and vadose zone) as employed in the EPA implementation of the Johnson and Ettinger model, the spatially and temporally averaged indoor concentrations in the case of groundwater sources can be higher than the ones estimated by the numerical model up to two orders of magnitude. In short, the model proposed in this work can represent an easy-to-use tool that can simulate the subsurface soil gas concentration in layered soils overlying a homogenous vapor source while keeping the simplicity of an analytical approach that requires much less computational effort.
Directory of Open Access Journals (Sweden)
Yi Yang
2017-03-01
Full Text Available Effective analysis of large text collections remains a challenging problem given the growing volume of available text data. Recently, text mining techniques have been rapidly developed for automatically extracting key information from massive text data. Topic modeling, as one of the novel techniques that extracts a thematic structure from documents, is widely used to generate text summarization and foster an overall understanding of the corpus content. Although powerful, this technique may not be directly applicable for general analytics scenarios since the topics and topicâdocument relationship are often presented probabilistically in models. Moreover, information that plays an important role in knowledge discovery, for example, times and authors, is hardly reflected in topic modeling for comprehensive analysis. In this paper, we address this issue by presenting a visual analytics system, VISTopic, to help users make sense of large document collections based on topic modeling. VISTopic first extracts a set of hierarchical topics using a novel hierarchical latent tree model (HLTM (Liu et al., 2014. In specific, a topic view accounting for the model features is designed for overall understanding and interactive exploration of the topic organization. To leverage multi-perspective information for visual analytics, VISTopic further provides an evolution view to reveal the trend of topics and a document view to show details of topical documents. Three case studies based on the dataset of IEEE VIS conference demonstrate the effectiveness of our system in gaining insights from large document collections. Keywords: Topic-modeling, Text visualization, Visual analytics
A two-dimensional analytical model of vapor intrusion involving vertical heterogeneity.
Yao, Yijun; Verginelli, Iason; Suuberg, Eric M
2017-05-01
In this work, we present an analytical chlorinated vapor intrusion (CVI) model that can estimate source-to-indoor air concentration attenuation by simulating two-dimensional (2-D) vapor concentration profile in vertically heterogeneous soils overlying a homogenous vapor source. The analytical solution describing the 2-D soil gas transport was obtained by applying a modified Schwarz-Christoffel mapping method. A partial field validation showed that the developed model provides results (especially in terms of indoor emission rates) in line with the measured data from a case involving a building overlying a layered soil. In further testing, it was found that the new analytical model can very closely replicate the results of three-dimensional (3-D) numerical models at steady state in scenarios involving layered soils overlying homogenous groundwater sources. By contrast, by adopting a two-layer approach (capillary fringe and vadose zone) as employed in the EPA implementation of the Johnson and Ettinger model, the spatially and temporally averaged indoor concentrations in the case of groundwater sources can be higher than the ones estimated by the numerical model up to two orders of magnitude. In short, the model proposed in this work can represent an easy-to-use tool that can simulate the subsurface soil gas concentration in layered soils overlying a homogenous vapor source while keeping the simplicity of an analytical approach that requires much less computational effort.
Comparison of a semi-analytic and a CFD model uranium combustion to experimental data
International Nuclear Information System (INIS)
Clarksean, R.
1998-01-01
Two numerical models were developed and compared for the analysis of uranium combustion and ignition in a furnace. Both a semi-analytical solution and a computational fluid dynamics (CFD) numerical solution were obtained. Prediction of uranium oxidation rates is important for fuel storage applications, fuel processing, and the development of spent fuel metal waste forms. The semi-analytical model was based on heat transfer correlations, a semi-analytical model of flow over a flat surface, and simple radiative heat transfer from the material surface. The CFD model numerically determined the flowfield over the object of interest, calculated the heat and mass transfer to the material of interest, and calculated the radiative heat exchange of the material with the furnace. The semi-analytical model is much less detailed than the CFD model, but yields reasonable results and assists in understanding the physical process. Short computation times allowed the analyst to study numerous scenarios. The CFD model had significantly longer run times, was found to have some physical limitations that were not easily modified, but was better able to yield details of the heat and mass transfer and flow field once code limitations were overcome
Directory of Open Access Journals (Sweden)
Elek Predrag M.
2015-01-01
Full Text Available Contemporary research in the field of explosive applications implies utilization of hydrocode simulations. Validity of these simulations strongly depends on parameters used in the equation of state for high explosives considered. A new analytical model for determination of Jones-Wilkins-Lee (JWL equation of state parameters based on the cylinder test is proposed. The model relies on analysis of the metal cylinder expansion by detonation products. Available cylinder test data for five high explosives are used for the calculation of JWL parameters. Good agreement between results of the model and the literature data is observed, justifying the suggested analytical approach. Numerical finite element model of the cylinder test is created in Abaqus in order to validate the proposed model. Using the analytical model results as the input, it was shown that numerical simulation of the cylinder test accurately reproduces experimental results for all considered high explosives. Therefore, both the analytical method for calculation of JWL equation of state parameters and numerical Abaqus model of the cylinder test are validated. [Projekat Ministartsva nauke Republike Srbije, br. III-47029
A Semi-Analytical Model for Short Range Dispersion From Ground Sources
Gavze, E.; Fattal, E.; Reichman, R.
2014-12-01
A semi-analytical model for dispersion of passive scalars from ground sources up to distances of a few hundred meters is presented. Most widely used analytical models are Gaussian models which assume both a uniform wind field and homogeneous turbulence. These assumptions are not valid when ground sources are involved since both the wind and the turbulence depend on height. The model presented here is free of these two assumptions. The formulation of the vertical dispersion is based on approximating the vertical profiles of the wind and the the vertical diffusion coefficient, based on Monin Obukhov Similarity Theory, as power laws. One advantage of this approach is that it allows for non Gaussian vertical profiles of the concentration which better fit the experimental data. For the lateral dispersion the model still assumes a Gaussian form. A system of equations was developed to compute the cloud width. This system of equations is based on an analytical solution of a Langevin equation which takes into account the non-homogeneity of the wind and the turbulence in the vertical direction. The model was tested against two field experiments. Comparison with a Gaussian model showed that it performed much better in predicting both the integrated cross wind ground concentration and the cloud width. Analytical, or semi-analytical models are useful as they are simple to use and require only a short computation time, compared, for example, to Lagrangian Stochastic Models. The presented model is very efficient from the computational point of view. As such it is suitable for cases in which repeated computations of the concentration field are required, as for example in risk assessments and in the inverse problem of source determination.
The role of decision analytic modeling in the health economic assessment of spinal intervention.
Edwards, Natalie C; Skelly, Andrea C; Ziewacz, John E; Cahill, Kevin; McGirt, Matthew J
2014-10-15
Narrative review. To review the common tenets, strengths, and weaknesses of decision modeling for health economic assessment and to review the use of decision modeling in the spine literature to date. For the majority of spinal interventions, well-designed prospective, randomized, pragmatic cost-effectiveness studies that address the specific decision-in-need are lacking. Decision analytic modeling allows for the estimation of cost-effectiveness based on data available to date. Given the rising demands for proven value in spine care, the use of decision analytic modeling is rapidly increasing by clinicians and policy makers. This narrative review discusses the general components of decision analytic models, how decision analytic models are populated and the trade-offs entailed, makes recommendations for how users of spine intervention decision models might go about appraising the models, and presents an overview of published spine economic models. A proper, integrated, clinical, and economic critical appraisal is necessary in the evaluation of the strength of evidence provided by a modeling evaluation. As is the case with clinical research, all options for collecting health economic or value data are not without their limitations and flaws. There is substantial heterogeneity across the 20 spine intervention health economic modeling studies summarized with respect to study design, models used, reporting, and general quality. There is sparse evidence for populating spine intervention models. Results mostly showed that interventions were cost-effective based on $100,000/quality-adjusted life-year threshold. Spine care providers, as partners with their health economic colleagues, have unique clinical expertise and perspectives that are critical to interpret the strengths and weaknesses of health economic models. Health economic models must be critically appraised for both clinical validity and economic quality before altering health care policy, payment strategies, or
Directory of Open Access Journals (Sweden)
Ajeng Diasputri
2015-11-01
Full Text Available This study aimed to know the influence of the use of a learning model Probing-prompting assisted by structured worksheet on learning outcomes in an high school especially in the Hydrocarbon and Petroleum. Sampling is done by using purposive sampling technique. In the experimental class, learning used Probing-prompting assisted by structured worksheet, while in classroom control used conventional methods. After being given a different treatment and after post test was done, it can be concluded that students' learning outcomes in class experiment is better than the control class, respectively 77 and 70. Based on the analysis of difference average learning outcomes, it obtained t count (4,074> t table (1,669, so it can be concluded that the average of learning outcomes in experimental class is better than the control class. In the test mastery learning, mastery percentage of experimental class reached 91.18% while control class reached 59.38%. Test correlation obtained biserial coefficient of 0.5638. It can be concluded that the learning model of Probing-prompting assisted by structured worksheet have significant effect on student learning outcomes on Hydrocarbons and Petroleum subject with contribution of 32%.
SPICE compatible analytical electron mobility model for biaxial strained-Si-MOSFETs
International Nuclear Information System (INIS)
Chaudhry, Amit; Sangwan, S.; Roy, J. N.
2011-01-01
This paper describes an analytical model for bulk electron mobility in strained-Si layers as a function of strain. Phonon scattering, columbic scattering and surface roughness scattering are included to analyze the full mobility model. Analytical explicit calculations of all of the parameters to accurately estimate the electron mobility have been made. The results predict an increase in the electron mobility with the application of biaxial strain as also predicted from the basic theory of strain physics of metal oxide semiconductor (MOS) devices. The results have also been compared with numerically reported results and show good agreement. (semiconductor devices)
Evaluation of subject contrast and normalized average glandular dose by semi-analytical models
International Nuclear Information System (INIS)
Tomal, A.; Poletti, M.E.; Caldas, L.V.E.
2010-01-01
In this work, two semi-analytical models are described to evaluate the subject contrast of nodules and the normalized average glandular dose in mammography. Both models were used to study the influence of some parameters, such as breast characteristics (thickness and composition) and incident spectra (kVp and target-filter combination) on the subject contrast of a nodule and on the normalized average glandular dose. From the subject contrast results, detection limits of nodules were also determined. Our results are in good agreement with those reported by other authors, who had used Monte Carlo simulation, showing the robustness of our semi-analytical method.
DEFF Research Database (Denmark)
Musaeus, Peter; Bennedsen, Andreas Brændstrup; Hansen, Janne Saltoft
2015-01-01
I denne artikel vil vi præsentere en strategi til inddragelse af læringsanalytik (learning analytics) ved evaluering af universitetsunderviseres brug af et nyt LMS på Aarhus Universitet: Blackboard. Vi diskuterer en model (BLAME: Blended Learning Analytics Model of Evaluation) for, hvordan...... kategorisering af kurser og data om læringsanalytik indsamlet på Blackboard kan integreres. Endvidere belyser vi, hvilke implikationer en sådan læringsanalytik kan have for blended learning ved at analysere to forskellige uddannelses-cases/illustrationer. Dernæst diskuterer vi pædagogisk udvikling i forbindelse...
Wang, Xi; Yang, Bintang; Yu, Hu; Gao, Yulong
2017-04-01
The impulse excitation of mechanism causes transient vibration. In order to achieve adaptive transient vibration control, a method which can exactly model the response need to be proposed. This paper presents an analytical model to obtain the response of the primary system attached with dynamic vibration absorber (DVA) under impulse excitation. The impulse excitation which can be divided into single-impulse excitation and multi-impulse excitation is simplified as sinusoidal wave to establish the analytical model. To decouple the differential governing equations, a transform matrix is applied to convert the response from the physical coordinate to model coordinate. Therefore, the analytical response in the physical coordinate can be obtained by inverse transformation. The numerical Runge-Kutta method and experimental tests have demonstrated the effectiveness of the analytical model proposed. The wavelet of the response indicates that the transient vibration consists of components with multiple frequencies, and it shows that the modeling results coincide with the experiments. The optimizing simulations based on genetic algorithm and experimental tests demonstrate that the transient vibration of the primary system can be decreased by changing the stiffness of the DVA. The results presented in this paper are the foundations for us to develop the adaptive transient vibration absorber in the future.
Variations on Debris Disks. IV. An Improved Analytical Model for Collisional Cascades
Kenyon, Scott J.; Bromley, Benjamin C.
2017-04-01
We derive a new analytical model for the evolution of a collisional cascade in a thin annulus around a single central star. In this model, r max the size of the largest object changes with time, {r}\\max \\propto {t}-γ , with γ ≈ 0.1-0.2. Compared to standard models where r max is constant in time, this evolution results in a more rapid decline of M d , the total mass of solids in the annulus, and L d , the luminosity of small particles in the annulus: {M}d\\propto {t}-(γ +1) and {L}d\\propto {t}-(γ /2+1). We demonstrate that the analytical model provides an excellent match to a comprehensive suite of numerical coagulation simulations for annuli at 1 au and at 25 au. If the evolution of real debris disks follows the predictions of the analytical or numerical models, the observed luminosities for evolved stars require up to a factor of two more mass than predicted by previous analytical models.
On Improving Analytical Models of Cosmic Reionization for Matching Numerical Simulations
Energy Technology Data Exchange (ETDEWEB)
Kaurov, Alexander A. [Univ. of Chicago, IL (United States)
2016-01-01
The methods for studying the epoch of cosmic reionization vary from full radiative transfer simulations to purely analytical models. While numerical approaches are computationally expensive and are not suitable for generating many mock catalogs, analytical methods are based on assumptions and approximations. We explore the interconnection between both methods. First, we ask how the analytical framework of excursion set formalism can be used for statistical analysis of numerical simulations and visual representation of the morphology of ionization fronts. Second, we explore the methods of training the analytical model on a given numerical simulation. We present a new code which emerged from this study. Its main application is to match the analytical model with a numerical simulation. Then, it allows one to generate mock reionization catalogs with volumes exceeding the original simulation quickly and computationally inexpensively, meanwhile reproducing large scale statistical properties. These mock catalogs are particularly useful for CMB polarization and 21cm experiments, where large volumes are required to simulate the observed signal.
Probing the (empirical quantum structure embedded in the periodic table with an effective Bohr model
Directory of Open Access Journals (Sweden)
Wellington Nardin Favaro
2013-01-01
Full Text Available The atomic shell structure can be observed by inspecting the experimental periodic properties of the Periodic Table. The (quantum shell structure emerges from these properties and in this way quantum mechanics can be explicitly shown considering the (semi-quantitative periodic properties. These periodic properties can be obtained with a simple effective Bohr model. An effective Bohr model with an effective quantum defect (u was considered as a probe in order to show the quantum structure embedded in the Periodic Table. u(Z shows a quasi-smoothed dependence of Z, i.e., u(Z ≈ Z2/5 - 1.
Analytical Model for LLC Resonant Converter With Variable Duty-Cycle Control
DEFF Research Database (Denmark)
Shen, Yanfeng; Wang, Huai; Blaabjerg, Frede
2016-01-01
are identified and discussed. The proposed model enables a better understanding of the operation characteristics and fast parameter design of the LLC converter, which otherwise cannot be achieved by the existing simulation based methods and numerical models. The results obtained from the proposed model......In LLC resonant converters, the variable duty-cycle control is usually combined with a variable frequency control to widen the gain range, improve the light-load efficiency, or suppress the inrush current during start-up. However, a proper analytical model for the variable duty-cycle controlled LLC...... converter is still not available due to the complexity of operation modes and the nonlinearity of steady-state equations. This paper makes the efforts to develop an analytical model for the LLC converter with variable duty-cycle control. All possible operation models and critical operation characteristics...
Analytic expressions for the construction of a fire event PSA model
International Nuclear Information System (INIS)
Kang, Dae Il; Kim, Kil Yoo; Kim, Dong San; Hwang, Mee Jeong; Yang, Joon Eon
2016-01-01
In this study, the changing process of an internal event PSA model to a fire event PSA model is analytically presented and discussed. Many fire PSA models have fire induced initiating event fault trees not shown in an internal event PSA model. Fire-induced initiating fault tree models are developed for addressing multiple initiating event issues. A single fire event within a fire compartment or fire scenario can cause multiple initiating events. As an example, a fire in a turbine building area can cause a loss of the main feed-water and loss of off-site power initiating events. Up to now, there has been no analytic study on the construction of a fire event PSA model using an internal event PSA model with fault trees of initiating events. In this paper, the changing process of an internal event PSA model to a fire event PSA model was analytically presented and discussed. This study results show that additional cutsets can be obtained if the fault trees of initiating events for a fire event PSA model are not exactly developed.
Schmidt, P J; Emelko, M B; Thompson, M E
2013-05-01
Quantitative microbial risk assessment (QMRA) is a tool to evaluate the potential implications of pathogens in a water supply or other media and is of increasing interest to regulators. In the case of potentially pathogenic protozoa (e.g. Cryptosporidium oocysts and Giardia cysts), it is well known that the methods used to enumerate (oo)cysts in samples of water and other media can have low and highly variable analytical recovery. In these applications, QMRA has evolved from ignoring analytical recovery to addressing it in point-estimates of risk, and then to addressing variation of analytical recovery in Monte Carlo risk assessments. Often, variation of analytical recovery is addressed in exposure assessment by dividing concentration values that were obtained without consideration of analytical recovery by random beta-distributed recovery values. A simple mathematical proof is provided to demonstrate that this conventional approach to address non-constant analytical recovery in drinking water QMRA will lead to overestimation of mean pathogen concentrations. The bias, which can exceed an order of magnitude, is greatest when low analytical recovery values are common. A simulated dataset is analyzed using a diverse set of approaches to obtain distributions representing temporal variation in the oocyst concentration, and mean annual risk is then computed from each concentration distribution using a simple risk model. This illustrative example demonstrates that the bias associated with mishandling non-constant analytical recovery and non-detect samples can cause drinking water systems to be erroneously classified as surpassing risk thresholds. Copyright © 2013 Elsevier Ltd. All rights reserved.
Bouchard, D.; Cornaton, F.; Höhener, P.; Hunkeler, D.
2011-01-01
Analytical models were developed that simulate stable isotope ratios of volatile organic compounds (VOCs) near a point source contamination in the unsaturated zone. The models describe diffusive transport of VOCs, biodegradation and source ageing. The mass transport is governed by Fick's law for diffusion. The equation for reactive transport of VOCs in the soil gas phase was solved for different source geometries and for different boundary conditions. Model results were compared to experiment...
Bennett, Iain; Paracha, Noman; Abrams, Keith; Ray, Joshua
2018-01-01
Rank Preserving Structural Failure Time models are one of the most commonly used statistical methods to adjust for treatment switching in oncology clinical trials. The method is often applied in a decision analytic model without appropriately accounting for additional uncertainty when determining the allocation of health care resources. The aim of the study is to describe novel approaches to adequately account for uncertainty when using a Rank Preserving Structural Failure Time model in a decision analytic model. Using two examples, we tested and compared the performance of the novel Test-based method with the resampling bootstrap method and with the conventional approach of no adjustment. In the first example, we simulated life expectancy using a simple decision analytic model based on a hypothetical oncology trial with treatment switching. In the second example, we applied the adjustment method on published data when no individual patient data were available. Mean estimates of overall and incremental life expectancy were similar across methods. However, the bootstrapped and test-based estimates consistently produced greater estimates of uncertainty compared with the estimate without any adjustment applied. Similar results were observed when using the test based approach on a published data showing that failing to adjust for uncertainty led to smaller confidence intervals. Both the bootstrapping and test-based approaches provide a solution to appropriately incorporate uncertainty, with the benefit that the latter can implemented by researchers in the absence of individual patient data. Copyright © 2018 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.
Directory of Open Access Journals (Sweden)
Dina V. Lazareva
2015-06-01
Full Text Available A new mathematical model of asymmetric support structure frame type is built on the basis of numerical-analytical boundary elements method (BEM. To describe the design scheme used is the graph theory. Building the model taken into account is the effect of frame members restrained torsion, which presence is due to the fact that these elements are thin-walled. The built model represents a real object as a two-axle semi-trailer platform. To implement the BEM algorithm obtained are analytical expressions of the fundamental functions and vector load components. The effected calculations are based on the semi-trailer two different models, using finite elements and boundary elements methods. The analysis showed that the error between the results obtained on the basis of two numerical methods and experimental data is about 4%, that indicates the adequacy of the proposed mathematical model.
An analytical model of a clamped sandwich beam under low-impulse mass impact
Directory of Open Access Journals (Sweden)
Wen-zheng Jiang
Full Text Available An analytical model is developed to examine a low impulsive projectile impact on a fully clamped sandwich beams by considering the coupled responses of the core and the face sheets. Firstly, based on the dynamic properties of foam cores, the sandwich beam is modeled as two rigid perfectly-plastic beams connected by rigid perfectly-plastic springs. Different from the previous sandwich beam model, the transverse compression and bending effects of the foam core are considered in the whole deformation process. Based on this model, different coupling mechanism of sandwich beams are constructed so that an analytical solution considering small deformation is derived. The coupled dynamic responses of sandwich beams with different core strengths are investigated. The results indicate that this model improves the prediction accuracy of the responses of the sandwich beams, and is available for the situation when the sandwich beam undergoes moderate global deformation.
Simulation of reactive geochemical transport in groundwater using a semi-analytical screening model
McNab, Walt W.
1997-10-01
A reactive geochemical transport model, based on a semi-analytical solution to the advective-dispersive transport equation in two dimensions, is developed as a screening tool for evaluating the impact of reactive contaminants on aquifer hydrogeochemistry. Because the model utilizes an analytical solution to the transport equation, it is less computationally intensive than models based on numerical transport schemes, is faster, and it is not subject to numerical dispersion effects. Although the assumptions used to construct the model preclude consideration of reactions between the aqueous and solid phases, thermodynamic mineral saturation indices are calculated to provide qualitative insight into such reactions. Test problems involving acid mine drainage and hydrocarbon biodegradation signatures illustrate the utility of the model in simulating essential hydrogeochemical phenomena.
Pignon, Baptiste; Sobotka, Vincent; Boyard, Nicolas; Delaunay, Didier
2017-10-01
Two different analytical models were presented to determine cycle parameters of thermoplastics injection process. The aim of these models was to provide quickly a first set of data for mold temperature and cooling time. The first model is specific to amorphous polymers and the second one is dedicated to semi-crystalline polymers taking the crystallization into account. In both cases, the nature of the contact between the polymer and the mold could be considered as perfect or not (thermal contact resistance was considered). Results from models are compared with experimental data obtained with an instrumented mold for an acrylonitrile butadiene styrene (ABS) and a polypropylene (PP). Good agreements were obtained for mold temperature variation and for heat flux. In the case of the PP, the analytical crystallization times were compared with those given by a coupled model between heat transfer and crystallization kinetics.
Analytical and numerical models of uranium ignition assisted by hydride formation
International Nuclear Information System (INIS)
Totemeier, T.C.; Hayes, S.L.
1996-01-01
Analytical and numerical models of uranium ignition assisted by the oxidation of uranium hydride are described. The models were developed to demonstrate that ignition of large uranium ingots could not occur as a result of possible hydride formation during storage. The thermodynamics-based analytical model predicted an overall 17 C temperature rise of the ingot due to hydride oxidation upon opening of the storage can in air. The numerical model predicted locally higher temperature increases at the surface; the transient temperature increase quickly dissipated. The numerical model was further used to determine conditions for which hydride oxidation does lead to ignition of uranium metal. Room temperature ignition only occurs for high hydride fractions in the nominally oxide reaction product and high specific surface areas of the uranium metal
Oliveri, Paolo
2017-08-22
Qualitative data modelling is a fundamental branch of pattern recognition, with many applications in analytical chemistry, and embraces two main families: discriminant and class-modelling methods. The first strategy is appropriate when at least two classes are meaningfully defined in the problem under study, while the second strategy is the right choice when the focus is on a single class. For this reason, class-modelling methods are also referred to as one-class classifiers. Although, in the food analytical field, most of the issues would be properly addressed by class-modelling strategies, the use of such techniques is rather limited and, in many cases, discriminant methods are forcedly used for one-class problems, introducing a bias in the outcomes. Key aspects related to the development, optimisation and validation of suitable class models for the characterisation of food products are critically analysed and discussed. Copyright © 2017 Elsevier B.V. All rights reserved.
Decision Making in Reference to Model of Marketing Predictive Analytics – Theory and Practice
Directory of Open Access Journals (Sweden)
Piotr Tarka
2014-03-01
Full Text Available Purpose: The objective of this paper is to describe concepts and assumptions of predictive marketing analytics in reference to decision making. In particular, we highlight issues pertaining to the importance of data and the modern approach to data analysis and processing with the purpose of solving real marketing problems that companies encounter in business. Methodology: In this paper authors provide two study cases showing how, and to what extent predictive marketing analytics work can be useful in practice e.g., investigation of the marketing environment. The two cases are based on organizations operating mainly on Web site domain. The fi rst part of this article, begins a discussion with the explanation of a general idea of predictive marketing analytics. The second part runs through opportunities it creates for companies in the process of building strong competitive advantage in the market. The paper article ends with a brief comparison of predictive analytics versus traditional marketing-mix analysis. Findings: Analytics play an extremely important role in the current process of business management based on planning, organizing, implementing and controlling marketing activities. Predictive analytics provides the actual and current picture of the external environment. They also explain what problems are faced with the company in business activities. Analytics tailor marketing solutions to the right time and place at minimum costs. In fact they control the effi ciency and simultaneously increases the effectiveness of the firm. Practical implications: Based on the study cases comparing two enterprises carrying business activities in different areas, one can say that predictive analytics has far more been embraces extensively than classical marketing-mix analyses. The predictive approach yields greater speed of data collection and analysis, stronger predictive accuracy, better obtained competitor data, and more transparent models where one can
Gharaee, H.; Rankin, R.; Marchand, R.; Paral, J.
2014-12-01
The ARTEMIS mission has made extensive measurements on the density and magnetic field structure of the lunar wake under different solar wind and magnetosphere conditions. Hybrid-kinetic simulations of the lunar wake have been found to be generally in good agreement with observations [Wiehle, S., et al., Planet. Space Sci., 2011], but are not readily available as they require access to large computers and human resources with expertise using this technology. It would be very useful to have an analytic model of the lunar wake, and one such model will be presented. It is based on an approach outlined by Hutchinson [Hutchinson, I., Physics Of Plasmas, 2008], and makes assumptions of cylindrical geometry, a strong and constant magnetic field, and fixed transverse velocity and temperature. Under these approximations the ion fluid equations (with massless electrons assumed) can be solved analytically by the method of characteristics. This paper demonstrates that the analytic model under these assumptions provides excellent agreement with observations and hybrid-kinetic simulations of the lunar wake. The approach outlined by Hutchinson is generalized to include an arbitrary angle between the interplanetary magnetic field and solar wind flow. This results in two angle-dependent characteristics for the fluid flow that can be solved for the density inside the wake region. The Density profiles for different orientations of magnetic field with respect to solar wind flow are in a good qualitative agreement with 2D Hybrid simulation results of the model developed by [Paral and Rankin, Nature Comms, 2012], and with ARTEMIS observations. Refrences, -Wiehle, S., et al. (2011), First Lunar wake passage of Artemis: Discrimination of wake effects and solar wind flactuations by 3D hybrid simulations, Planet. Space Sci., 59, 661-671, doi:10.1016/j.pss.2011.01.012. -Hutchinson, I. (2008),Oblique ion collection in the drift approximation:How magnetized Mach probes really work, Physics Of
An efficient analytical model for baffled, multi-celled membrane-type acoustic metamaterial panels
Langfeldt, F.; Gleine, W.; von Estorff, O.
2018-03-01
A new analytical model for the oblique incidence sound transmission loss prediction of baffled panels with multiple subwavelength sized membrane-type acoustic metamaterial (MAM) unit cells is proposed. The model employs a novel approach via the concept of the effective surface mass density and approximates the unit cell vibrations in the form of piston-like displacements. This yields a coupled system of linear equations that can be solved efficiently using well-known solution procedures. A comparison with results from finite element model simulations for both normal and diffuse field incidence shows that the analytical model delivers accurate results as long as the edge length of the MAM unit cells is smaller than half the acoustic wavelength. The computation times for the analytical calculations are 100 times smaller than for the numerical simulations. In addition to that, the effect of flexible MAM unit cell edges compared to the fixed edges assumed in the analytical model is studied numerically. It is shown that the compliance of the edges has only a small impact on the transmission loss of the panel, except at very low frequencies in the stiffness-controlled regime. The proposed analytical model is applied to investigate the effect of variations of the membrane prestress, added mass, and mass eccentricity on the diffuse transmission loss of a MAM panel with 120 unit cells. Unlike most previous investigations of MAMs, these results provide a better understanding of the acoustic performance of MAMs under more realistic conditions. For example, it is shown that by varying these parameters deliberately in a checkerboard pattern, a new anti-resonance with large transmission loss values can be introduced. A random variation of these parameters, on the other hand, is shown to have only little influence on the diffuse transmission loss, as long as the standard deviation is not too large. For very large random variations, it is shown that the peak transmission loss
The Use of Decision-Analytic Models in Atopic Eczema: A Systematic Review and Critical Appraisal.
McManus, Emma; Sach, Tracey; Levell, Nick
2018-01-01
The objective of this systematic review was to identify and assess the quality of published economic decision-analytic models within atopic eczema against best practice guidelines, with the intention of informing future decision-analytic models within this condition. A systematic search of the following online databases was performed: MEDLINE, EMBASE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane Central Register of Controlled Trials, Database of Abstracts of Reviews of Effects, Cochrane Database of Systematic Reviews, NHS Economic Evaluation Database, EconLit, Scopus, Health Technology Assessment, Cost-Effectiveness Analysis Registry and Web of Science. Papers were eligible for inclusion if they described a decision-analytic model evaluating both the costs and benefits associated with an intervention or prevention for atopic eczema. Data were extracted using a standardised form by two independent reviewers, whilst quality was assessed using the model-specific Philips criteria. Twenty-four models were identified, evaluating either preventions (n = 12) or interventions (n = 12): 14 reported using a Markov modelling approach, four utilised decision trees and one a discrete event simulation, whilst five did not specify the approach. The majority, 22 studies, reported that the intervention was dominant or cost effective, given the assumptions and analytical perspective taken. Notably, the models tended to be short-term (16 used a time horizon of ≤1 year), often providing little justification for the limited time horizon chosen. The methodological and reporting quality of the studies was generally weak, with only seven studies fulfilling more than 50% of their applicable Philips criteria. This is the first systematic review of decision models in eczema. Whilst the majority of models reported favourable outcomes in terms of the cost effectiveness of the new intervention, the usefulness of these findings for decision-making is
New integrable models and analytical solutions in f (R ) cosmology with an ideal gas
Papagiannopoulos, G.; Basilakos, Spyros; Barrow, John D.; Paliathanasis, Andronikos
2018-01-01
In the context of f (R ) gravity with a spatially flat FLRW metric containing an ideal fluid, we use the method of invariant transformations to specify families of models which are integrable. We find three families of f (R ) theories for which new analytical solutions are given and closed-form solutions are provided.
An analytical model for the heat generation in friction stir welding
DEFF Research Database (Denmark)
Schmidt, Henrik Nikolaj Blich; Hattel, Jesper; Wert, John
2004-01-01
The objective of this work is to establish an analytical model for heat generation by friction stir welding (FSW), based on different assumptions of the contact condition between the rotating tool surface and the weld piece. The material flow and heat generation are characterized by the contact...
An Analytical Model for Fatigue Life Prediction Based on Fracture Mechanics and Crack Closure
DEFF Research Database (Denmark)
Ibsø, Jan Behrend; Agerskov, Henning
1996-01-01
test specimens are compared with fatigue life predictions using a fracture mechanics approach. In the calculation of the fatigue life, the influence of the welding residual stresses and crack closure on the fatigue crack growth is considered. A description of the crack closure model for analytical...
The Effectiveness of CBL Model to Improve Analytical Thinking Skills the Students of Sport Science
Sudibyo, Elok; Jatmiko, Budi; Widodo, Wahono
2016-01-01
Sport science undergraduate education, one of which purposes is to produce an analyst in sport. However, generally analytical thinking skills of sport science's students is still relatively very low in the context of sport. This study aimed to describe the effectiveness of Physics Learning Model in Sport Context, Context Based Learning (CBL)…
An analytical model for studying noise effects in PWR type reactors
International Nuclear Information System (INIS)
Meyer, K.
1975-10-01
An analytical model based on the one-group diffusion method is described. It has been used for calculating the axial dependence of the spectral density of the ionization chamber noise supposing a site-independent stationary neutron flux distribution. Coolant inlet temperature fluctuations are considered as noise sources. (author)
Analytical model for relativistic corrections to the nuclear magnetic shielding constant in atoms
International Nuclear Information System (INIS)
Romero, Rodolfo H.; Gomez, Sergio S.
2006-01-01
We present a simple analytical model for calculating and rationalizing the main relativistic corrections to the nuclear magnetic shielding constant in atoms. It provides good estimates for those corrections and their trends, in reasonable agreement with accurate four-component calculations and perturbation methods. The origin of the effects in deep core atomic orbitals is manifestly shown
Analytical model for relativistic corrections to the nuclear magnetic shielding constant in atoms
Energy Technology Data Exchange (ETDEWEB)
Romero, Rodolfo H. [Facultad de Ciencias Exactas, Universidad Nacional del Nordeste, Avenida Libertad 5500 (3400), Corrientes (Argentina)]. E-mail: rhromero@exa.unne.edu.ar; Gomez, Sergio S. [Facultad de Ciencias Exactas, Universidad Nacional del Nordeste, Avenida Libertad 5500 (3400), Corrientes (Argentina)
2006-04-24
We present a simple analytical model for calculating and rationalizing the main relativistic corrections to the nuclear magnetic shielding constant in atoms. It provides good estimates for those corrections and their trends, in reasonable agreement with accurate four-component calculations and perturbation methods. The origin of the effects in deep core atomic orbitals is manifestly shown.
An analytical kinetic model for chemical-vapor deposition of pureB layers from diborane
Mohammadi, V.; De Boer, W.B.; Nanver, L.K.
2012-01-01
In this paper, an analytical model is established to describe the deposition kinetics and the deposition chamber characteristics that determine the deposition rates of pure boron (PureB-) layers grown by chemical-vapor deposition (CVD) from diborane (B2H6) as gas source on a non-rotating silicon
A structurally based analytic model for estimation of biomass and fuel loads of woodland trees
Robin J. Tausch
2009-01-01
Allometric/structural relationships in tree crowns are a consequence of the physical, physiological, and fluid conduction processes of trees, which control the distribution, efficient support, and growth of foliage in the crown. The structural consequences of these processes are used to develop an analytic model based on the concept of branch orders. A set of...
Salentijn, Gert Ij; Oomen, Pieter E; Grajewski, Maciej; Verpoorte, Elisabeth
2017-01-01
In this work, the use of fused deposition modeling (FDM) in a (bio)analytical/lab-on-a-chip research laboratory is described. First, the specifications of this 3D printing method that are important for the fabrication of (micro)devices were characterized for a benchtop FDM 3D printer. These include
An Analytical Framework for Evaluating E-Commerce Business Models and Strategies.
Lee, Chung-Shing
2001-01-01
Considers electronic commerce as a paradigm shift, or a disruptive innovation, and presents an analytical framework based on the theories of transaction costs and switching costs. Topics include business transformation process; scale effect; scope effect; new sources of revenue; and e-commerce value creation model and strategy. (LRW)
Calvert, Carol Elaine
2014-01-01
This case study relates to distance learning students on open access courses. It demonstrates the use of predictive analytics to generate a model of the probabilities of success and retention at different points, or milestones, in a student journey. A core set of explanatory variables has been established and their varying relative importance at…
Analytical model of asymmetrical Mixed-Mode Bending test of adhesively bonded GFRP joint
Czech Academy of Sciences Publication Activity Database
Ševčík, Martin; Hutař, Pavel; Vassilopoulos, Anastasios P.; Shahverdi, M.
2015-01-01
Roč. 9, č. 34 (2015), s. 237-246 ISSN 1971-8993 R&D Projects: GA MŠk(CZ) EE2.3.30.0063; GA ČR GA15-09347S Institutional support: RVO:68081723 Keywords : GFRP materials * Mixed-Mode bending * Fiber bridging * Analytical model Subject RIV: JL - Materials Fatigue, Friction Mechanics
The analytic structure of lattice models – Why can't we solve most ...
Indian Academy of Sciences (India)
Analytic structure of lattice models implicitly or explicitly. One might settle for a polynomial time algorithm to produce the coefficients in the series expansion of the solution. Here we will show how to conjecture, and then in some cases prove [1–3] that the above list of unsolved problems, as well as bond animals, bond trees, ...
International Nuclear Information System (INIS)
Anderson, A.; Eriksson, L.G.; Lisak, M.
1986-01-01
The present report summarizes the work performed within the contract JT4/9008, the aim of which is to derive analytical models for ion velocity distributions resulting from ICRF heating on JET. The work has been performed over a two-year-period ending in August 1986 and has involved a total effort of 2.4 man years. (author)
Czech Academy of Sciences Publication Activity Database
Tlustý, J.; Škramlík, Jiří; Švec, J.; Valouch, Viktor
2012-01-01
Roč. 2012, č. 292178 (2012), s. 1-17 ISSN 1024-123X Institutional support: RVO:61388998 Keywords : analytical modeling * four-switch hybrid power filter * sixfold switching symmetry Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.383, year: 2012 http://www.hindawi.com/journals/mpe/2012/292178/
Ganser, Christian; Czibula, Caterina; Tscharnuter, Daniel; Schöberl, Thomas; Teichert, Christian; Hirn, Ulrich
2017-12-20
Viscoelastic properties are often measured using probe based techniques such as nanoindentation (NI) and atomic force microscopy (AFM). Rarely, however, are these methods verified. In this article, we present a method that combines contact mechanics with a viscoelastic model (VEM) composed of springs and dashpots. We further show how to use this model to determine viscoelastic properties from creep curves recorded by a probe based technique. We focus on using the standard linear solid model and the generalized Maxwell model of order 2. The method operates in the range of 0.01 Hz to 1 Hz. Our approach is suitable for rough surfaces by providing a defined contact area using plastic pre-deformation of the material. The very same procedure is used to evaluate AFM based measurements as well as NI measurements performed on polymer samples made from poly(methyl methacrylate) and polycarbonate. The results of these measurements are then compared to those obtained by tensile creep tests also performed on the same samples. It is found that the tensile test results differ considerably from the results obtained by AFM and NI methods. The similarity between the AFM results and NI results suggests that the proposed method is capable of yielding results comparable to NI but with the advantage of the imaging possibilities of AFM. Furthermore, all three methods allowed a clear distinction between PC and PMMA by means of their respective viscoelastic properties.
Zhang, Yongquan; Tang, Huiming; Li, Changdong; Lu, Guiying; Cai, Yi; Zhang, Junrong; Tan, Fulin
2018-01-14
The physical model test of landslides is important for studying landslide structural damage, and parameter measurement is key in this process. To meet the measurement requirements for deep displacement in landslide physical models, an automatic flexible inclinometer probe with good coupling and large deformation capacity was designed. The flexible inclinometer probe consists of several gravity acceleration sensing units that are protected and positioned by silicon encapsulation, all the units are connected to a 485-comunication bus. By sensing the two-axis tilt angle, the direction and magnitude of the displacement for a measurement unit can be calculated, then the overall displacement is accumulated according to all units, integrated from bottom to top in turn. In the conversion from angle to displacement, two spline interpolation methods are introduced to correct and resample the data; one is to interpolate the displacement after conversion, and the other is to interpolate the angle before conversion; compared with the result read from checkered paper, the latter is proved to have a better effect, with an additional condition that the displacement curve move up half the length of the unit. The flexible inclinometer is verified with respect to its principle and arrangement by a laboratory physical model test, and the test results are highly consistent with the actual deformation of the landslide model.
Merlin, Olivier; Al Bitar, Ahmad; Rivalland, Vincent; Béziat, Pierre; Ceschia, Eric; Dedieu, Gérard
2010-01-01
doi: 10.1175/2010JAMC2418.1; Analytical expressions of evaporative efficiency over bare soil (defined as the ratio of actual to potential soil evaporation) have been limited to soil layers with a fixed depth and/or to specific atmospheric conditions. To fill the gap, a new analytical model is developed for arbitrary soil thicknesses and varying boundary layer conditions. The soil evaporative efficiency is written [0.5 – 0.5 cos(πθL/ θmax)]^P with θL being the water content in the soil layer o...
Evaluation of the Component Chemical Potentials in Analytical Models for Ordered Alloy Phases
Directory of Open Access Journals (Sweden)
W. A. Oates
2011-01-01
Full Text Available The component chemical potentials in models of solution phases with a fixed number of sites can be evaluated easily when the Helmholtz energy is known as an analytical function of composition. In the case of ordered phases, however, the situation is less straightforward, because the Helmholtz energy is a functional involving internal order parameters. Because of this, the chemical potentials are usually obtained numerically from the calculated integral Helmholtz energy. In this paper, we show how the component chemical potentials can be obtained analytically in ordered phases via the use of virtual cluster chemical potentials. Some examples are given which illustrate the simplicity of the method.
Energy Technology Data Exchange (ETDEWEB)
Kleimann, Jens; Fichtner, Horst [Ruhr-Universität Bochum, Fakultät für Physik und Astronomie, Institut für Theoretische Physik IV, Bochum (Germany); Röken, Christian, E-mail: jk@tp4.rub.de, E-mail: hf@tp4.rub.de, E-mail: christian.roeken@mathematik.uni-regensburg.de [Universität Regensburg, Fakultät für Mathematik, Regensburg (Germany)
2017-03-20
A previously published analytical magnetohydrodynamic model for the local interstellar magnetic field in the vicinity of the heliopause (Röken et al. 2015) is extended from incompressible to compressible, yet predominantly subsonic flow, considering both isothermal and adiabatic equations of state. Exact expressions and suitable approximations for the density and the flow velocity are derived and discussed. In addition to the stationary induction equation, these expressions also satisfy the momentum balance equation along stream lines. The practical usefulness of the corresponding, still exact, analytical magnetic field solution is assessed by comparing it quantitatively to results from a fully self-consistent magnetohydrodynamic simulation of the interstellar magnetic field draping around the heliopause.
Lee, Ping I
2011-10-10
The purpose of this review is to provide an overview of approximate analytical solutions to the general moving boundary diffusion problems encountered during the release of a dispersed drug from matrix systems. Starting from the theoretical basis of the Higuchi equation and its subsequent improvement and refinement, available approximate analytical solutions for the more complicated cases involving heterogeneous matrix, boundary layer effect, finite release medium, surface erosion, and finite dissolution rate are also discussed. Among various modeling approaches, the pseudo-steady state assumption employed in deriving the Higuchi equation and related approximate analytical solutions appears to yield reasonably accurate results in describing the early stage release of a dispersed drug from matrices of different geometries whenever the initial drug loading (A) is much larger than the drug solubility (C(s)) in the matrix (or A≫C(s)). However, when the drug loading is not in great excess of the drug solubility (i.e. low A/C(s) values) or when the drug loading approaches the drug solubility (A→C(s)) which occurs often with drugs of high aqueous solubility, approximate analytical solutions based on the pseudo-steady state assumption tend to fail, with the Higuchi equation for planar geometry exhibiting a 11.38% error as compared with the exact solution. In contrast, approximate analytical solutions to this problem without making the pseudo-steady state assumption, based on either the double-integration refinement of the heat balance integral method or the direct simplification of available exact analytical solutions, show close agreement with the exact solutions in different geometries, particularly in the case of low A/C(s) values or drug loading approaching the drug solubility (A→C(s)). However, the double-integration heat balance integral approach is generally more useful in obtaining approximate analytical solutions especially when exact solutions are not
International Nuclear Information System (INIS)
Montesinos, J.L.; Poch, M.; Alonso, J.; Valle, M. del; Lima, J.L.F.C.
1991-01-01
Results obtained in the evaluation of a mathematical model for flow-injection sandwich systems, in which the sample is inserted between two different carrier solutions with the aid of an eight-way injection valve, are presented. The model considers the system as a tubular reactor with axially dispersed plug flow, where chemical kinetics have been included. Only a minimum of parameters are needed for the model: the dispersion coefficients, which are obtained from experimental correlations for the different hydrodynamic conditions, and the rate constants, which are determined by univariate optimization. The behaviour of the model, when applied to the case of one analyte and one reagent, was evaluated for the enzymatic determinations of glucose and glycerol. The case of two analytes determined with two reagents was also studied in the combined determination of glucose and glycerol. Experimental profiles were compared with the simulated peaks and showed good agreement. (author). 20 refs.; 11 figs.; 2 tabs
Directory of Open Access Journals (Sweden)
Xiangyue Lin
2017-12-01
Full Text Available Based on the assumptions of uniform corrosion and linear elastic expansion, an analytical model of cracking due to rebar corrosion expansion in concrete was established, which is able to consider the structure internal force. And then, by means of the complex variable function theory and series expansion technology established by Muskhelishvili, the corresponding stress component functions of concrete around the reinforcement were obtained. Also, a comparative analysis was conducted between the numerical simulation model and present model in this paper. The results show that the calculation results of both methods were consistent with each other, and the numerical deviation was less than 10%, proving that the analytical model established in this paper is reliable.
Energy Technology Data Exchange (ETDEWEB)
Montesinos, J.L.; Poch, M. (Universitat Autonoma de Barcelona (Spain). Departament de Quimica, Unitat d' Enginyera Quimica); Alonso, J.; Valle, M. del (Universitat Autonoma de Barcelona (Spain). Departament de Quimica, Unitat de Quimica Analitica); Lima, J.L.F.C. (Universidade de Porto (Portugal). Faculdade de Farmacia, Departamento de Quimica Fisica)
1991-11-20
Results obtained in the evaluation of a mathematical model for flow-injection sandwich systems, in which the sample is inserted between two different carrier solutions with the aid of an eight-way injection valve, are presented. The model considers the system as a tubular reactor with axially dispersed plug flow, where chemical kinetics have been included. Only a minimum of parameters are needed for the model: the dispersion coefficients, which are obtained from experimental correlations for the different hydrodynamic conditions, and the rate constants, which are determined by univariate optimization. The behaviour of the model, when applied to the case of one analyte and one reagent, was evaluated for the enzymatic determinations of glucose and glycerol. The case of two analytes determined with two reagents was also studied in the combined determination of glucose and glycerol. Experimental profiles were compared with the simulated peaks and showed good agreement. (author). 20 refs.; 11 figs.; 2 tabs.
A Meshless Algorithm to Model Field Evaporation in Atom Probe Tomography.
Rolland, Nicolas; Vurpillot, François; Duguay, Sébastien; Blavette, Didier
2015-12-01
An alternative approach for simulating the field evaporation process in atom probe tomography is presented. The model uses the electrostatic Robin's equation to directly calculate charge distribution over the tip apex conducting surface, without the need for a supporting mesh. The partial ionization state of the surface atoms is at the core of the method. Indeed, each surface atom is considered as a point charge, which is representative of its evaporation probability. The computational efficiency is ensured by an adapted version of the Barnes-Hut N-body problem algorithm. Standard desorption maps for cubic structures are presented in order to demonstrate the effectiveness of the method.
A novel stress distribution analytical model of O-ring seals under different properties of materials
Energy Technology Data Exchange (ETDEWEB)
Wu, Di; Wang, Shao Ping; Wang, Xing Jian [School of Automation Science and Electrical Engineering, Beihang University, Beijing (China)
2017-01-15
The elastomeric O-ring seals have been widely used as sealing elements in hydraulic systems. The sealing performance of O-ring seals is related to stress distribution. The stresses distribution depends on the squeeze rate and internal pressure, and would vary with properties of O-ring seals materials. Thus, in order to study the sealing performance of O-ring seals, it is necessary to describe the analytic relationship between stress distribution and properties of O-ring seals materials. For this purpose, a novel Stress distribution analytical model (SDAM) is proposed in this paper. The analytical model utilizes two stress complex functions to describe the stress distribution of O-ring seals. The proposed SDAM can express not only the analytical relationship between stress distribution and Young’s modulus, but also the one between stress distribution and Poisson’s ratio. Finally, compared results between finite element analysis and the SDAM validate that the proposed model can effectively reveal the stress distribution under different properties for O-ring materials.
An analytical model of thermal mechanical stress induced by through silicon via
International Nuclear Information System (INIS)
Dong Gang; Shi Tao; Zhao Ying-Bo; Yang Yin-Tang
2015-01-01
We present an accurate through silicon via (TSV) thermal mechanical stress analytical model which is verified by using finite element method (FEM). The results show only a very small error. By using the proposed analytical model, we also study the impacts of the TSV radius size, the thickness, the material of Cu diffusion barrier, and liner on the stress. It is found that the liner can absorb the stress effectively induced by coefficient of thermal expansion mismatch. The stress decreases with the increase of liner thickness. Benzocyclobutene (BCB) as a liner material is better than SiO 2 . However, the Cu diffusion barrier has little effect on the stress. The stress with a smaller TSV has a smaller value. Based on the analytical model, we explore and validate the linear superposition principle of stress tensors and demonstrate the accuracy of this method against detailed FEM simulations. The analytic solutions of stress of two TSVs and three TSVs have high precision against the finite element result. (paper)
Leij, Feike J; Bradford, Scott A
2009-11-20
The transport of solutes and colloids in porous media is influenced by a variety of physical and chemical nonequilibrium processes. A combined physical-chemical nonequilibrium (PCNE) model was therefore used to describe general mass transport. The model partitions the pore space into "mobile" and "immobile" flow regions with first-order mass transfer between these two regions (i.e, "physical" nonequilibrium or PNE). Partitioning between the aqueous and solid phases can either proceed as an equilibrium or a first-order process (i.e, "chemical" nonequilibrium or CNE) for both the mobile and immobile regions. An analytical solution for the PCNE model is obtained using iterated Laplace transforms. This solution complements earlier semi-analytical and numerical approaches to model solute transport with the PCNE model. The impact of selected model parameters on solute breakthrough curves is illustrated. As is well known, nonequilibrium results in earlier solute breakthrough with increased tailing. The PCNE model allows greater flexibility to describe this trend; for example, a closer resemblance between solute input and effluent pulse. Expressions for moments and transfer functions are presented to facilitate the analytical use of the PCNE model. Contours of mean breakthrough time, variance, and spread of the colloid breakthrough curves as a function of PNE and CNE parameters demonstrate the utility of a model that accounts for both physical and chemical nonequilibrium processes. The model is applied to describe representative colloid breakthrough curves in Ottawa sands reported by Bradford et al. (2002). An equilibrium model provided a good description of breakthrough curves for the bromide tracer but could not adequately describe the colloid data. A considerably better description was provide by the simple CNE model but the best description, especially for the larger 3.2-microm colloids, was provided by the PCNE model.
Modeling Hybridization Kinetics of Gene Probes in a DNA Biochip Using FEMLAB
Munir, Ahsan; Waseem, Hassan; Williams, Maggie R.; Stedtfeld, Robert D.; Gulari, Erdogan; Tiedje, James M.; Hashsham, Syed A.
2017-01-01
Microfluidic DNA biochips capable of detecting specific DNA sequences are useful in medical diagnostics, drug discovery, food safety monitoring and agriculture. They are used as miniaturized platforms for analysis of nucleic acids-based biomarkers. Binding kinetics between immobilized single stranded DNA on the surface and its complementary strand present in the sample are of interest. To achieve optimal sensitivity with minimum sample size and rapid hybridization, ability to predict the kinetics of hybridization based on the thermodynamic characteristics of the probe is crucial. In this study, a computer aided numerical model for the design and optimization of a flow-through biochip was developed using a finite element technique packaged software tool (FEMLAB; package included in COMSOL Multiphysics) to simulate the transport of DNA through a microfluidic chamber to the reaction surface. The model accounts for fluid flow, convection and diffusion in the channel and on the reaction surface. Concentration, association rate constant, dissociation rate constant, recirculation flow rate, and temperature were key parameters affecting the rate of hybridization. The model predicted the kinetic profile and signal intensities of eighteen 20-mer probes targeting vancomycin resistance genes (VRGs). Predicted signal intensities and hybridization kinetics strongly correlated with experimental data in the biochip (R2 = 0.8131). PMID:28555058
Modeling Hybridization Kinetics of Gene Probes in a DNA Biochip Using FEMLAB
Directory of Open Access Journals (Sweden)
Ahsan Munir
2017-05-01
Full Text Available Microfluidic DNA biochips capable of detecting specific DNA sequences are useful in medical diagnostics, drug discovery, food safety monitoring and agriculture. They are used as miniaturized platforms for analysis of nucleic acids-based biomarkers. Binding kinetics between immobilized single stranded DNA on the surface and its complementary strand present in the sample are of interest. To achieve optimal sensitivity with minimum sample size and rapid hybridization, ability to predict the kinetics of hybridization based on the thermodynamic characteristics of the probe is crucial. In this study, a computer aided numerical model for the design and optimization of a flow-through biochip was developed using a finite element technique packaged software tool (FEMLAB; package included in COMSOL Multiphysics to simulate the transport of DNA through a microfluidic chamber to the reaction surface. The model accounts for fluid flow, convection and diffusion in the channel and on the reaction surface. Concentration, association rate constant, dissociation rate constant, recirculation flow rate, and temperature were key parameters affecting the rate of hybridization. The model predicted the kinetic profile and signal intensities of eighteen 20-mer probes targeting vancomycin resistance genes (VRGs. Predicted signal intensities and hybridization kinetics strongly correlated with experimental data in the biochip (R2 = 0.8131.
Energy Technology Data Exchange (ETDEWEB)
Hasan, IIftekhar; Husain, Tausif; Uddin, Md Wasi; Sozer, Yilmaz; Husain; Iqbal; Muljadi, Eduard
2015-08-24
This paper presents a nonlinear analytical model of a novel double-sided flux concentrating Transverse Flux Machine (TFM) based on the Magnetic Equivalent Circuit (MEC) model. The analytical model uses a series-parallel combination of flux tubes to predict the flux paths through different parts of the machine including air gaps, permanent magnets, stator, and rotor. The two-dimensional MEC model approximates the complex three-dimensional flux paths of the TFM and includes the effects of magnetic saturation. The model is capable of adapting to any geometry that makes it a good alternative for evaluating prospective designs of TFM compared to finite element solvers that are numerically intensive and require more computation time. A single-phase, 1-kW, 400-rpm machine is analytically modeled, and its resulting flux distribution, no-load EMF, and torque are verified with finite element analysis. The results are found to be in agreement, with less than 5% error, while reducing the computation time by 25 times.
Magnetohydrodynamic modeling of three Van Allen Probes storms in 2012 and 2013
Directory of Open Access Journals (Sweden)
J. Paral
2015-08-01
Full Text Available Coronal mass ejection (CME-shock compression of the dayside magnetopause has been observed to cause both prompt enhancement of radiation belt electron flux due to inward radial transport of electrons conserving their first adiabatic invariant and prompt losses which at times entirely eliminate the outer zone. Recent numerical studies suggest that enhanced ultra-low frequency (ULF wave activity is necessary to explain electron losses deeper inside the magnetosphere than magnetopause incursion following CME-shock arrival. A combination of radial transport and magnetopause shadowing can account for losses observed at radial distances into L = 4.5, well within the computed magnetopause location. We compare ULF wave power from the Electric Field and Waves (EFW electric field instrument on the Van Allen Probes for the 8 October 2013 storm with ULF wave power simulated using the Lyon–Fedder–Mobarry (LFM global magnetohydrodynamic (MHD magnetospheric simulation code coupled to the Rice Convection Model (RCM. Two other storms with strong magnetopause compression, 8–9 October 2012 and 17–18 March 2013, are also examined. We show that the global MHD model captures the azimuthal magnetosonic impulse propagation speed and amplitude observed by the Van Allen Probes which is responsible for prompt acceleration at MeV energies reported for the 8 October 2013 storm. The simulation also captures the ULF wave power in the azimuthal component of the electric field, responsible for acceleration and radial transport of electrons, at frequencies comparable to the electron drift period. This electric field impulse has been shown to explain observations in related studies (Foster et al., 2015 of electron acceleration and drift phase bunching by the Energetic Particle, Composition, and Thermal Plasma Suite (ECT instrument on the Van Allen Probes.
Directory of Open Access Journals (Sweden)
Zhichao Wu
2017-01-01
Full Text Available A new electromechanical coupling model was built to quantitatively analyze the tuning fork probes, especially the complex ones. A special feature of a novel, soft tuning fork probe, that the second eigenfrequency of the probe was insensitive to the effective force gradient, was found and used in a homemade bimodal atomic force microscopy to measure power dissipation quantitatively. By transforming the mechanical parameters to the electrical parameters, a monotonous and concise method without using phase to calculate the power dissipation was proposed.
Giri, Ashutosh; Hopkins, Patrick E
2016-02-28
We develop an analytical model for the thermal boundary conductance between a solid and a gas. By considering the thermal fluxes in the solid and the gas, we describe the transmission of energy across the solid/gas interface with diffuse mismatch theory. From the predicted thermal boundary conductances across solid/gas interfaces, the equilibrium thermal accommodation coefficient is determined and compared to predictions from molecular dynamics simulations on the model solid-gas systems. We show that our model is applicable for modeling the thermal accommodation of gases on solid surfaces at non-cryogenic temperatures and relatively strong solid-gas interactions (ε(sf) ≳ k(B)T).
On the absence of analytic integrability of the Bianchi Class B cosmological models
Ferragut, Antoni
2013-01-01
El títol de la versió pre-print de l'article és: Analytic integrability of the Bianchi Class B cosmological model Bianchi models are cosmological models that describe space–times which are foliated by homogeneous hypersurfaces of constant time and are divided into two classes, Class A and Class B. There are many studies about the integrability of Class A. Here we study the integrability of Class B. For the homogeneous cosmological models of Class B, Einstein’s system of differential equati...
An analytic model for gate-all-around silicon nanowire tunneling field effect transistors
Liu, Ying; He, Jin; Chan, Mansun; Du, Cai-Xia; Ye, Yun; Zhao, Wei; Wu, Wen; Deng, Wan-Ling; Wang, Wen-Ping
2014-09-01
An analytical model of gate-all-around (GAA) silicon nanowire tunneling field effect transistors (NW-TFETs) is developted based on the surface potential solutions in the channel direction and considering the band to band tunneling (BTBT) efficiency. The three-dimensional Poisson equation is solved to obtain the surface potential distributions in the partition regions along the channel direction for the NW-TFET, and a tunneling current model using Kane's expression is developed. The validity of the developed model is shown by the good agreement between the model predictions and the TCAD simulation results.
An Analytical Model for Spectral Peak Frequency Prediction of Substrate Noise in CMOS Substrates
DEFF Research Database (Denmark)
Shen, Ming; Mikkelsen, Jan H.
2013-01-01
This paper proposes an analytical model describing the generation of switching current noise in CMOS substrates. The model eliminates the need for SPICE simulations in existing methods by conducting a transient analysis on a generic CMOS inverter and approximating the switching current waveform us......- ing a Modified Raised Cosine (MORAC) equation. The proposed model is scalable, easy to implement and capable of predicting the spectral peak frequency of the substrate noise. The validation has been done via simulations and measurements. Good agreement has been found between the modeled...
International Nuclear Information System (INIS)
Chan, T.; Nakka, B.W.
1994-12-01
A two-dimensional analytical well model has been developed to describe steady groundwater flow in an idealized, confined aquifer intersected by a withdrawal well. The aquifer comprises a low-dipping fracture zone. The model is useful for making simple quantitative estimates of the transport of contaminants along groundwater pathways in the fracture zone to the well from an underground source that intercepts the fracture zone. This report documents the mathematical development of the analytical well model. It outlines the assumptions and method used to derive an exact analytical solution, which is verified by two other methods. It presents expressions for calculating quantities such as streamlines (groundwater flow paths), fractional volumetric flow rates, contaminant concentration in well water and minimum convective travel time to the well. In addition, this report presents the results of applying the analytical model to a site-specific conceptual model of the Whiteshell Research Area in southeastern Manitoba, Canada. This hydrogeological model includes the presence of a 20-m-thick, low-dipping (18 deg) fracture zone (LD1) that intercepts the horizon of a hypothetical disposal vault located at a depth of 500 m. A withdrawal well intercepts LD1 between the vault level and the ground surface. Predictions based on parameters and boundary conditions specific to LD1 are presented graphically. The analytical model has specific applications in the SYVAC geosphere model (GEONET) to calculate the fraction of a plume of contaminants moving up the fracture zone that is captured by the well, and to describe the drawdown in the hydraulic head in the fracture zone caused by the withdrawal well. (author). 16 refs., 6 tabs., 35 figs
A semi-analytical stationary model of a point-to-plane corona discharge
International Nuclear Information System (INIS)
Yanallah, K; Pontiga, F
2012-01-01
A semi-analytical model of a dc corona discharge is formulated to determine the spatial distribution of charged particles (electrons, negative ions and positive ions) and the electric field in pure oxygen using a point-to-plane electrode system. A key point in the modeling is the integration of Gauss' law and the continuity equation of charged species along the electric field lines, and the use of Warburg's law and the corona current–voltage characteristics as input data in the boundary conditions. The electric field distribution predicted by the model is compared with the numerical solution obtained using a finite-element technique. The semi-analytical solutions are obtained at a negligible computational cost, and provide useful information to characterize and control the corona discharge in different technological applications. (paper)
Analytical boron diffusivity model in silicon for thermal diffusion from boron silicate glass film
Kurachi, Ikuo; Yoshioka, Kentaro
2015-09-01
An analytical boron diffusivity model in silicon for thermal diffusion from a boron silicate glass (BSG) film has been proposed in terms of enhanced diffusion due to boron-silicon interstitial pair formation. The silicon interstitial generation is considered to be a result of the silicon kick-out mechanism by the diffused boron at the surface. The additional silicon interstitial generation in the bulk silicon is considered to be the dissociation of the diffused pairs. The former one causes the surface boron concentration dependent diffusion. The latter one causes the local boron concentration dependent diffusion. The calculated boron profiles based on the diffusivity model are confirmed to agree with the actual diffusion profiles measured by secondary ion mass spectroscopy (SIMS) for a wide range of the BSG boron concentration. This analytical diffusivity model is a helpful tool for p+ boron diffusion process optimization of n-type solar cell manufacturing.
An analytical model of anisotropic low-field electron mobility in wurtzite indium nitride
Energy Technology Data Exchange (ETDEWEB)
Wang, Shulong; Liu, Hongxia; Song, Xin; Guo, Yulong; Yang, Zhaonian [Xidian University, School of Microelectronics, Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xi' an (China)
2014-03-15
This paper presents a theoretical analysis of anisotropic transport properties and develops an anisotropic low-field electron analytical mobility model for wurtzite indium nitride (InN). For the different effective masses in the Γ-A and Γ-M directions of the lowest valley, both the transient and steady state transport behaviors of wurtzite InN show different transport characteristics in the two directions. From the relationship between velocity and electric field, the difference is more obvious when the electric field is low in the two directions. To make an accurate description of the anisotropic transport properties under low field, for the first time, we present an analytical model of anisotropic low-field electron mobility in wurtzite InN. The effects of different ionized impurity scattering models on the low-field mobility calculated by Monte Carlo method (Conwell-Weisskopf and Brooks-Herring method) are also considered. (orig.)
Directory of Open Access Journals (Sweden)
Ana Rusmerg Giménez Ledesma
2013-05-01
Full Text Available The main objective of this paper is to propose an analytical-prospective model as a tool to support decision-making processes concerning metrology, standardization and regulation of nanomaterials in Brazil, based on international references and ongoing initiatives in the world. In the context of nanotechnology development in Brazil, the motivation for carrying out this research was to identify potential benefits of metrology, standardization and regulation of nanomaterials production, from the perspective of future adoption of the model by the main stakeholders of development of these areas in Brazil. The main results can be summarized as follows: (i an overview of international studies on metrology, standardization and regulation of nanomaterials, and nanoparticles, in special; (ii the analytical-prospective model; and (iii the survey questionnaire and the roadmapping tool for metrology, standardization and regulation of nanomaterials in Brazil, based on international references and ongoing initiatives in the world.
Bernegger, R.; Altenburg, S. J.; Röllig, M.; Maierhofer, C.
2018-03-01
Pulse thermography (PT) has proven to be a valuable non-destructive testing method to identify and quantify defects in fiber-reinforced polymers. To perform a quantitative defect characterization, the heat diffusion within the material as well as the material parameters must be known. The heterogeneous material structure of glass fiber-reinforced polymers (GFRP) as well as the semitransparency of the material for optical excitation sources of PT is still challenging. For homogeneous semitransparent materials, 1D analytical models describing the temperature distribution are available. Here, we present an analytical approach to model PT for laterally inhomogeneous semitransparent materials. We show the validity of the model by considering different configurations of the optical heating source, the IR camera, and the differently coated GFRP sample. The model considers the lateral inhomogeneity of the semitransparency by an additional absorption coefficient. It includes additional effects such as thermal losses at the samples surfaces, multilayer systems with thermal contact resistance, and a finite duration of the heating pulse. By using a sufficient complexity of the analytical model, similar values of the material parameters were found for all six investigated configurations by numerical fitting.
An Analytical Model for CMUTs with Square Multilayer Membranes Using the Ritz Method
Directory of Open Access Journals (Sweden)
Wen Zhang
2016-03-01
Full Text Available Capacitive micromachined ultrasonic transducer (CMUT multilayer membrane plays an important role in the performance metrics including the transmitting efficiency and the receiving sensitivity. However, there are few studies of the multilayer membranes. Some analytical models simplify the multilayer membrane as monolayer, which results in inaccuracies. This paper presents a new analytical model for CMUTs with multilayer membranes, which can rapidly and accurately predict static deflection and response frequency of the multilayer membrane under external pressures. The derivation is based on the Ritz method and Hamilton’s principle. The mathematical relationships between the external pressure, static deflection, and response frequency are obtained. Relevant residual stress compensation method is derived. The model has been verified for three-layer and double-layer CMUT membranes by comparing its results with finite element method (FEM simulations, experimental data, and other monolayer models that treat CMUTs as monolayer plates/membranes. For three-layer CMUT membranes, the relative errors are ranging from 0.71%–3.51% for the static deflection profiles, and 0.35%–4.96% for the response frequencies, respectively. For the double-layer CMUT membrane, the relative error with residual stress compensation is 4.14% for the central deflection, and −1.17% for the response frequencies, respectively. This proposed analytical model can serve as a reliable reference and an accurate tool for CMUT design and optimization.
Analytical Business Model for Sustainable Distributed Retail Enterprises in a Competitive Market
Directory of Open Access Journals (Sweden)
Courage Matobobo
2016-02-01
Full Text Available Retail enterprises are organizations that sell goods in small quantities to consumers for personal consumption. In distributed retail enterprises, data is administered per branch. It is important for retail enterprises to make use of data generated within the organization to determine consumer patterns and behaviors. Large organizations find it difficult to ascertain customer preferences by merely observing transactions. This has led to quantifiable losses, such as loss of market share to competitors and targeting the wrong market. Although some enterprises have implemented classical business models to address these challenging issues, they still lack analytics-based marketing programs to gain a competitive advantage to deal with likely catastrophic events. This research develops an analytical business (ARANN model for distributed retail enterprises in a competitive market environment to address the current laxity through the best arrangement of shelf products per branch. The ARANN model is built on association rules, complemented by artificial neural networks to strengthen the results of both mutually. According to experimental analytics, the ARANN model outperforms the state of the art model, implying improved confidence in business information management within the dynamically changing world economy.
A Novel Analytical Model to Design Piezoelectric Patches Used to Repair Cracked Beams
Directory of Open Access Journals (Sweden)
Waleed Al-Ashtari
2016-06-01
Full Text Available In this paper, an analytical solution describing the deflection of a cracked beam repaired with piezoelectric patch is introduced. The solution is derived using perturbation method. A novel analytical model to calculate the proper dimensions of piezoelectric patches used to repair cracked beams is also introduced. This model shows that the thickness of the piezoelectric patch depends mainly on the thickness of the cracked beam, the electro-mechanical properties of the patch material, the applied load and the crack location. Furthermore, the model shows that the length of the piezoelectric patches depends on the thickness of the patch as well as it depends on the length of the cracked beam and the crack depth. The additional flexibility of the beam caused by crack is modeled depending on a dimensionless parameter identified from finite elements method. Different piezoelectric patches were designed and investigated using analytical and finite elements models. The results show that increasing the patch thickness enhances the beam resistance to crack and load effects, while increasing the length of the piezoelectric patch reduces the magnitude of the voltage required to repair the cracked beam.
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.
Residential Saudi load forecasting using analytical model and Artificial Neural Networks
Al-Harbi, Ahmad Abdulaziz
In recent years, load forecasting has become one of the main fields of study and research. Short Term Load Forecasting (STLF) is an important part of electrical power system operation and planning. This work investigates the applicability of different approaches; Artificial Neural Networks (ANNs) and hybrid analytical models to forecast residential load in Kingdom of Saudi Arabia (KSA). These two techniques are based on model human modes behavior formulation. These human modes represent social, religious, official occasions and environmental parameters impact. The analysis is carried out on residential areas for three regions in two countries exposed to distinct people activities and weather conditions. The collected data are for Al-Khubar and Yanbu industrial city in KSA, in addition to Seattle, USA to show the validity of the proposed models applied on residential load. For each region, two models are proposed. First model is next hour load forecasting while second model is next day load forecasting. Both models are analyzed using the two techniques. The obtained results for ANN next hour models yield very accurate results for all areas while relatively reasonable results are achieved when using hybrid analytical model. For next day load forecasting, the two approaches yield satisfactory results. Comparative studies were conducted to prove the effectiveness of the models proposed.
Zurweni, Wibawa, Basuki; Erwin, Tuti Nurian
2017-08-01
The framework for teaching and learning in the 21st century was prepared with 4Cs criteria. Learning providing opportunity for the development of students' optimal creative skills is by implementing collaborative learning. Learners are challenged to be able to compete, work independently to bring either individual or group excellence and master the learning material. Virtual laboratory is used for the media of Instrumental Analytical Chemistry (Vis, UV-Vis-AAS etc) lectures through simulations computer application and used as a substitution for the laboratory if the equipment and instruments are not available. This research aims to design and develop collaborative-creative learning model using virtual laboratory media for Instrumental Analytical Chemistry lectures, to know the effectiveness of this design model adapting the Dick & Carey's model and Hannafin & Peck's model. The development steps of this model are: needs analyze, design collaborative-creative learning, virtual laboratory media using macromedia flash, formative evaluation and test of learning model effectiveness. While, the development stages of collaborative-creative learning model are: apperception, exploration, collaboration, creation, evaluation, feedback. Development of collaborative-creative learning model using virtual laboratory media can be used to improve the quality learning in the classroom, overcome the limitation of lab instruments for the real instrumental analysis. Formative test results show that the Collaborative-Creative Learning Model developed meets the requirements. The effectiveness test of students' pretest and posttest proves significant at 95% confidence level, t-test higher than t-table. It can be concluded that this learning model is effective to use for Instrumental Analytical Chemistry lectures.
An analytical framework to assist decision makers in the use of forest ecosystem model predictions
Larocque, Guy R.; Bhatti, Jagtar S.; Ascough, J.C.; Liu, J.; Luckai, N.; Mailly, D.; Archambault, L.; Gordon, Andrew M.
2011-01-01
The predictions from most forest ecosystem models originate from deterministic simulations. However, few evaluation exercises for model outputs are performed by either model developers or users. This issue has important consequences for decision makers using these models to develop natural resource management policies, as they cannot evaluate the extent to which predictions stemming from the simulation of alternative management scenarios may result in significant environmental or economic differences. Various numerical methods, such as sensitivity/uncertainty analyses, or bootstrap methods, may be used to evaluate models and the errors associated with their outputs. However, the application of each of these methods carries unique challenges which decision makers do not necessarily understand; guidance is required when interpreting the output generated from each model. This paper proposes a decision flow chart in the form of an analytical framework to help decision makers apply, in an orderly fashion, different steps involved in examining the model outputs. The analytical framework is discussed with regard to the definition of problems and objectives and includes the following topics: model selection, identification of alternatives, modelling tasks and selecting alternatives for developing policy or implementing management scenarios. Its application is illustrated using an on-going exercise in developing silvicultural guidelines for a forest management enterprise in Ontario, Canada.
Number of Clusters and the Quality of Hybrid Predictive Models in Analytical CRM
Directory of Open Access Journals (Sweden)
Łapczyński Mariusz
2014-08-01
Full Text Available Making more accurate marketing decisions by managers requires building effective predictive models. Typically, these models specify the probability of customer belonging to a particular category, group or segment. The analytical CRM categories refer to customers interested in starting cooperation with the company (acquisition models, customers who purchase additional products (cross- and up-sell models or customers intending to resign from the cooperation (churn models. During building predictive models researchers use analytical tools from various disciplines with an emphasis on their best performance. This article attempts to build a hybrid predictive model combining decision trees (C&RT algorithm and cluster analysis (k-means. During experiments five different cluster validity indices and eight datasets were used. The performance of models was evaluated by using popular measures such as: accuracy, precision, recall, G-mean, F-measure and lift in the first and in the second decile. The authors tried to find a connection between the number of clusters and models' quality.
The Super-NFW model: an analytic dynamical model for cold dark matter haloes and elliptical galaxies
Lilley, Edward J.; Wyn Evans, N.; Sanders, Jason L.
2018-02-01
An analytic galaxy model with ρ ˜ r-1 at small radii and ρ ˜ r-3.5 at large radii is presented. The asymptotic density fall-off is slower than the Hernquist model, but faster than the Navarro-Frenk-White (NFW) profile for dark matter haloes, and so in accord with recent evidence from cosmological simulations. The model provides the zeroth-order term in a biorthornomal basis function expansion, meaning that axisymmetric, triaxial and lopsided distortions can easily be added (much like the Hernquist model itself which is the zeroth-order term of the Hernquist-Ostriker expansion). The properties of the spherical model, including analytic distribution functions which are either isotropic, radially anisotropic or tangentially anisotropic, are discussed in some detail. The analogue of the mass-concentration relation for cosmological haloes is provided.
Analytical spectral density of the Sachdev-Ye-Kitaev model at finite N
García-García, Antonio M.; Verbaarschot, Jacobus J. M.
2017-09-01
We derive an approximate analytical formula for the spectral density of the q -body Sachdev-Ye-Kitaev (SYK) model obtained by summing a class of diagrams representing leading intersecting contractions. This expression agrees with that of Q -Hermite polynomials, with Q a nontrivial function of q ≥2 and the number of Majorana fermions N . Numerical results, obtained by exact diagonalization, are in excellent agreement with this approximate analytical spectral density even for relatively small N ˜8 . For N ≫1 and not close to the edge of the spectrum, we find that the approximate analytical spectral density simplifies to ρasym(E )=exp [2 arcsin2(E /E0)/log η ] , where η (N ,q ) is the suppression factor of the contribution of intersecting Wick contractions relative to nested contractions and E0 is the ground-state energy per particle. This spectral density reproduces the known result for the free energy in the large-q and large-N limit at arbitrary values of the temperature. In the infrared region, where the SYK model is believed to have a gravity dual, the analytical spectral density is given by ρ (E )˜sinh [2 π √{2 }√{(1 -E /E0)/(-log η ) }] . It therefore has a square-root edge, as in random matrix ensembles, followed by an exponential growth, a distinctive feature of black holes and also of low-energy nuclear excitations. Results for level statistics in this region confirm the agreement with random matrix theory. Physically this is a signature that, for sufficiently long times, the SYK model and its gravity dual evolve to a fully ergodic state whose dynamics only depends on the global symmetry of the system. Our results strongly suggest that random matrix correlations are a universal feature of quantum black holes and that the SYK model, combined with holography, may be relevant to modeling certain aspects of the nuclear dynamics.
Analytical solution for the anisotropic Rabi model: effects of counter-rotating terms.
Zhang, Guofeng; Zhu, Hanjie
2015-03-04
The anisotropic Rabi model, which was proposed recently, differs from the original Rabi model: the rotating and counter-rotating terms are governed by two different coupling constants. This feature allows us to vary the counter-rotating interaction independently and explore the effects of it on some quantum properties. In this paper, we eliminate the counter-rotating terms approximately and obtain the analytical energy spectrums and wavefunctions. These analytical results agree well with the numerical calculations in a wide range of the parameters including the ultrastrong coupling regime. In the weak counter-rotating coupling limit we find out that the counter-rotating terms can be considered as the shifts to the parameters of the Jaynes-Cummings model. This modification shows the validness of the rotating-wave approximation on the assumption of near-resonance and relatively weak coupling. Moreover, the analytical expressions of several physics quantities are also derived, and the results show the break-down of the U(1)-symmetry and the deviation from the Jaynes-Cummings model.
Analytical calculation of detailed model parameters of cast resin dry-type transformers
International Nuclear Information System (INIS)
Eslamian, M.; Vahidi, B.; Hosseinian, S.H.
2011-01-01
Highlights: → In this paper high frequency behavior of cast resin dry-type transformers was simulated. → Parameters of detailed model were calculated using analytical method and compared with FEM results. → A lab transformer was constructed in order to compare theoretical and experimental results. -- Abstract: Non-flammable characteristic of cast resin dry-type transformers make them suitable for different kind of usages. This paper presents an analytical method of how to obtain parameters of detailed model of these transformers. The calculated parameters are compared and verified with the corresponding FEM results and if it was necessary, correction factors are introduced for modification of the analytical solutions. Transient voltages under full and chopped test impulses are calculated using the obtained detailed model. In order to validate the model, a setup was constructed for testing on high-voltage winding of cast resin dry-type transformer. The simulation results were compared with the experimental data measured from FRA and impulse tests.
Accurate analytical modeling of junctionless DG-MOSFET by green's function approach
Nandi, Ashutosh; Pandey, Nilesh
2017-11-01
An accurate analytical model of Junctionless double gate MOSFET (JL-DG-MOSFET) in the subthreshold regime of operation is developed in this work using green's function approach. The approach considers 2-D mixed boundary conditions and multi-zone techniques to provide an exact analytical solution to 2-D Poisson's equation. The Fourier coefficients are calculated correctly to derive the potential equations that are further used to model the channel current and subthreshold slope of the device. The threshold voltage roll-off is computed from parallel shifts of Ids-Vgs curves between the long channel and short-channel devices. It is observed that the green's function approach of solving 2-D Poisson's equation in both oxide and silicon region can accurately predict channel potential, subthreshold current (Isub), threshold voltage (Vt) roll-off and subthreshold slope (SS) of both long & short channel devices designed with different doping concentrations and higher as well as lower tsi/tox ratio. All the analytical model results are verified through comparisons with TCAD Sentaurus simulation results. It is observed that the model matches quite well with TCAD device simulations.
Analytical model of SiPM time resolution and order statistics with crosstalk
Energy Technology Data Exchange (ETDEWEB)
Vinogradov, S., E-mail: Sergey.Vinogradov@liverpool.ac.uk [University of Liverpool and Cockcroft Institute, Sci-Tech Daresbury, Keckwick Lane, Warrington WA4 4AD (United Kingdom); P.N. Lebedev Physical Institute of the Russian Academy of Sciences, 119991 Leninskiy Prospekt 53, Moscow (Russian Federation)
2015-07-01
Time resolution is the most important parameter of photon detectors in a wide range of time-of-flight and time correlation applications within the areas of high energy physics, medical imaging, and others. Silicon photomultipliers (SiPM) have been initially recognized as perfect photon-number-resolving detectors; now they also provide outstanding results in the scintillator timing resolution. However, crosstalk and afterpulsing introduce false secondary non-Poissonian events, and SiPM time resolution models are experiencing significant difficulties with that. This study presents an attempt to develop an analytical model of the timing resolution of an SiPM taking into account statistics of secondary events resulting from a crosstalk. Two approaches have been utilized to derive an analytical expression for time resolution: the first one based on statistics of independent identically distributed detection event times and the second one based on order statistics of these times. The first approach is found to be more straightforward and “analytical-friendly” to model analog SiPMs. Comparisons of coincidence resolving times predicted by the model with the known experimental results from a LYSO:Ce scintillator and a Hamamatsu MPPC are presented.
An accurate analytical solution of a zero-dimensional greenhouse model for global warming
International Nuclear Information System (INIS)
Foong, S K
2006-01-01
In introducing the complex subject of global warming, books and papers usually use the zero-dimensional greenhouse model. When the ratio of the infrared radiation energy of the Earth's surface that is lost to outer space to the non-reflected average solar radiation energy is small, the model admits an accurate approximate analytical solution-the resulting energy balance equation of the model is a quartic equation that can be solved analytically-and thus provides an alternative solution and instructional strategy. A search through the literature fails to find an analytical solution, suggesting that the solution may be new. In this paper, we review the model, derive the approximation and obtain its solution. The dependence of the temperature of the surface of the Earth and the temperature of the atmosphere on seven parameters is made explicit. A simple and convenient formula for global warming (or cooling) in terms of the percentage change of the parameters is derived. The dependence of the surface temperature on the parameters is illustrated by several representative graphs
Analytical model of SiPM time resolution and order statistics with crosstalk
International Nuclear Information System (INIS)
Vinogradov, S.
2015-01-01
Time resolution is the most important parameter of photon detectors in a wide range of time-of-flight and time correlation applications within the areas of high energy physics, medical imaging, and others. Silicon photomultipliers (SiPM) have been initially recognized as perfect photon-number-resolving detectors; now they also provide outstanding results in the scintillator timing resolution. However, crosstalk and afterpulsing introduce false secondary non-Poissonian events, and SiPM time resolution models are experiencing significant difficulties with that. This study presents an attempt to develop an analytical model of the timing resolution of an SiPM taking into account statistics of secondary events resulting from a crosstalk. Two approaches have been utilized to derive an analytical expression for time resolution: the first one based on statistics of independent identically distributed detection event times and the second one based on order statistics of these times. The first approach is found to be more straightforward and “analytical-friendly” to model analog SiPMs. Comparisons of coincidence resolving times predicted by the model with the known experimental results from a LYSO:Ce scintillator and a Hamamatsu MPPC are presented
OEDGE Modeling of Collector Probe measurements in L-mode from the DIII-D tungsten ring campaign
Elder, J. D.; Stangeby, P. C.; Unterberg, Z.; Donovan, D.; Wampler, W. R.; Watkins, J.; Abrams, T.; McLean, A. G.
2017-10-01
During the tungsten ring campaign on DIII-D, a collector probe system with multiple diameter, dual-facing collector rods was inserted into the far scrape off layer (SOL) near the outer midplane to measure the plasma tungsten content. For most probes more tungsten was observed on the side connected along field lines to the inner divertor, with the larger probes showing largest divertor-facing asymmetries The OEDGE code is used to model the tungsten erosion, transport and deposition. It has been enhanced with (i) a peripheral particle transport and deposition model to record the impurity content in the peripheral region outside the regular mesh, and (ii) a collector probe model. The OEDGE results approximately reproduce both the divertor-facing asymmetries and the radial decay of each collector probe profile. The effect of changing impurity transport assumptions and wall location are examined. The measured divertor-facing asymmetries imply a higher tungsten density in the plasma upstream of the probe; this was expected theoretically from the effect of the parallel ion temperature gradient force driving upstream transport of tungsten from the outer divertor and was also found in the code analysis. Work supported by the US Department of Energy under DE-FC02-04ER54698, DE-NA0003525, DE-AC05-00OR22725, and DE-AC52-07NA27344.
Summers, Richard L; Pipke, Matt; Wegerich, Stephan; Conkright, Gary; Isom, Kristen C
2014-01-01
Background. Monitoring cardiovascular hemodynamics in the modern clinical setting is a major challenge. Increasing amounts of physiologic data must be analyzed and interpreted in the context of the individual patients pathology and inherent biologic variability. Certain data-driven analytical methods are currently being explored for smart monitoring of data streams from patients as a first tier automated detection system for clinical deterioration. As a prelude to human clinical trials, an empirical multivariate machine learning method called Similarity-Based Modeling (SBM), was tested in an In Silico experiment using data generated with the aid of a detailed computer simulator of human physiology (Quantitative Circulatory Physiology or QCP) which contains complex control systems with realistic integrated feedback loops. Methods. SBM is a kernel-based, multivariate machine learning method that that uses monitored clinical information to generate an empirical model of a patients physiologic state. This platform allows for the use of predictive analytic techniques to identify early changes in a patients condition that are indicative of a state of deterioration or instability. The integrity of the technique was tested through an In Silico experiment using QCP in which the output of computer simulations of a slowly evolving cardiac tamponade resulted in progressive state of cardiovascular decompensation. Simulator outputs for the variables under consideration were generated at a 2-min data rate (0.083Hz) with the tamponade introduced at a point 420 minutes into the simulation sequence. The functionality of the SBM predictive analytics methodology to identify clinical deterioration was compared to the thresholds used by conventional monitoring methods. Results. The SBM modeling method was found to closely track the normal physiologic variation as simulated by QCP. With the slow development of the tamponade, the SBM model are seen to disagree while the
A two-parameter nondiffusive heat conduction model for data analysis in pump-probe experiments
Ma, Yanbao
2014-12-01
Nondiffusive heat transfer has attracted intensive research interests in last 50 years because of its importance in fundamental physics and engineering applications. It has unique features that cannot be described by the Fourier law. However, current studies of nondiffusive heat transfer still focus on studying the effective thermal conductivity within the framework of the Fourier law due to a lack of a well-accepted replacement. Here, we show that nondiffusive heat conduction can be characterized by two inherent material properties: a diffusive thermal conductivity and a ballistic transport length. We also present a two-parameter heat conduction model and demonstrate its validity in different pump-probe experiments. This model not only offers new insights of nondiffusive heat conduction but also opens up new avenues for the studies of nondiffusive heat transfer outside the framework of the Fourier law.
Directory of Open Access Journals (Sweden)
Wanjie Xu
2015-01-01
Full Text Available A physically based subthreshold current model for silicon nanowire transistors working in the ballistic regime is developed. Based on the electric potential distribution obtained from a 2D Poisson equation and by performing some perturbation approximations for subband energy levels, an analytical model for the subthreshold drain current is obtained. The model is further used for predicting the subthreshold slopes and threshold voltages of the transistors. Our results agree well with TCAD simulation with different geometries and under different biasing conditions.
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
Original analytic solution of a half-bridge modelled as a statically indeterminate system
Oanta, Emil M.; Panait, Cornel; Raicu, Alexandra; Barhalescu, Mihaela
2016-12-01
The paper presents an original computer based analytical model of a half-bridge belonging to a circular settling tank. The primary unknown is computed using the force method, the coefficients of the canonical equation being calculated using either the discretization of the bending moment diagram in trapezoids, or using the relations specific to the polygons. A second algorithm based on the method of initial parameters is also presented. Analyzing the new solution we came to the conclusion that most of the computer code developed for other model may be reused. The results are useful to evaluate the behavior of the structure and to compare with the results of the finite element models.
Development of an analytical model to assess fuel property effects on combustor performance
Sutton, R. D.; Troth, D. L.; Miles, G. A.; Riddlebaugh, S. M.
1987-01-01
A generalized first-order computer model has been developed in order to analytically evaluate the potential effect of alternative fuels' effects on gas turbine combustors. The model assesses the size, configuration, combustion reliability, and durability of the combustors required to meet performance and emission standards while operating on a broad range of fuels. Predictions predicated on combustor flow-field determinations by the model indicate that fuel chemistry, as defined by hydrogen content, exerts a significant influence on flame retardation, liner wall temperature, and smoke emission.
Analytical thermal model for end-pumped solid-state lasers
Cini, L.; Mackenzie, J. I.
2017-12-01
Fundamentally power-limited by thermal effects, the design challenge for end-pumped "bulk" solid-state lasers depends upon knowledge of the temperature gradients within the gain medium. We have developed analytical expressions that can be used to model the temperature distribution and thermal-lens power in end-pumped solid-state lasers. Enabled by the inclusion of a temperature-dependent thermal conductivity, applicable from cryogenic to elevated temperatures, typical pumping distributions are explored and the results compared with accepted models. Key insights are gained through these analytical expressions, such as the dependence of the peak temperature rise in function of the boundary thermal conductance to the heat sink. Our generalized expressions provide simple and time-efficient tools for parametric optimization of the heat distribution in the gain medium based upon the material and pumping constraints.
Directory of Open Access Journals (Sweden)
T. Aly Saandy
2015-08-01
Full Text Available Abstract This article presents to an analytical calculation methodology of the Steinmetz coefficient applied to the prediction of Eddy current loss in a single-phase transformer. Based on the electrical circuit theory the active power consumed by the core is expressed analytically in function of the electrical parameters as resistivity and the geometrical dimensions of the core. The proposed modeling approach is established with the duality parallel series. The required coefficient is identified from the empirical Steinmetz data based on the experimented active power expression. To verify the relevance of the model validations both by simulations with two in two different frequencies and measurements were carried out. The obtained results are in good agreement with the theoretical approach and the practical results.
Analytic models of spectral responses of fiber-grating-based interferometers on FMC theory.
Zeng, Xiangkai; Wei, Lai; Pan, Yingjun; Liu, Shengping; Shi, Xiaohui
2012-02-13
In this paper the analytic models (AMs) of the spectral responses of fiber-grating-based interferometers are derived from the Fourier mode coupling (FMC) theory proposed recently. The interferometers include Fabry-Perot cavity, Mach-Zehnder and Michelson interferometers, which are constructed by uniform fiber Bragg gratings and long-period fiber gratings, and also by Gaussian-apodized ones. The calculated spectra based on the analytic models are achieved, and compared with the measured cases and those on the transfer matrix (TM) method. The calculations and comparisons have confirmed that the AM-based spectrum is in excellent agreement with the TM-based one and the measured case, of which the efficiency is improved up to ~2990 times that of the TM method for non-uniform-grating-based in-fiber interferometers.
International Nuclear Information System (INIS)
Weatherby, J.R.; Clauss, D.B.
1987-01-01
Under the sponsorship of the US Nuclear Regulatory Commission, Sandia National Laboratories is investigating methods for predicting the structural performance of nuclear reactor containment buildings under hypothesized severe accident conditions. As part of this program, a 1/6th-scale reinforced concrete containment model will be pressurized to failure in early 1987. Data generated by the test will be compared to analytical predictions of the structural response in order to assess the accuracy and reliability of the analytical techniques. As part of the pretest analysis effort, Sandia has conducted a number of analyses of the containment structure using the ABAQUS general purpose finite element code. This paper describes results from a nonlinear axisymmetric shell analysis as well as the material models and failure criteria used in conjunction with the analysis
Directory of Open Access Journals (Sweden)
Peter Musaeus
2015-02-01
Full Text Available I denne artikel vil vi præsentere en strategi til inddragelse af læringsanalytik (learning analytics ved evaluering af universitetsunderviseres brug af et nyt LMS på Aarhus Universitet: Blackboard. Vi diskuterer en model (BLAME: Blended Learning Analytics Model of Evaluation for, hvordan kategorisering af kurser og data om læringsanalytik indsamlet på Blackboard kan integreres. Endvidere belyser vi, hvilke implikationer en sådan læringsanalytik kan have for blended learning ved at analysere to forskellige uddannelses-cases/illustrationer. Dernæst diskuterer vi pædagogisk udvikling i forbindelse med evalueringsrapport om underviseres brug af Blackboard som beslutningsstøtte for feedback og pædagogisk intervention. Artiklen slutter med en diskussion af, hvordan data til læringsanalytik bør indsamles i LMS og bruges til afrapportering og undervisningsudvikling.
Directory of Open Access Journals (Sweden)
Pijcke Benoit
2011-01-01
Full Text Available Abstract In this paper, we propose a methodology for estimating the statistics of the intercell interference power in the downlink of a multicellular network. We first establish an analytical expression for the probability law of the interference power when only Rayleigh multipath fading is considered. Next, focusing on a propagation environment where small-scale Rayleigh fading as well as large-scale effects, including attenuation with distance and lognormal shadowing, are taken into consideration, we elaborate a semi-analytical method to build up the histogram of the interference power distribution. From the results obtained for this combined small- and large-scale fading context, we then develop a statistical model for the interference power distribution. The interest of this model lies in the fact that it can be applied to a large range of values of the shadowing parameter. The proposed methods can also be easily extended to other types of networks.
Environmental concentrations of engineered nanomaterials: Review of modeling and analytical studies
International Nuclear Information System (INIS)
Gottschalk, Fadri; Sun, TianYin; Nowack, Bernd
2013-01-01
Scientific consensus predicts that the worldwide use of engineered nanomaterials (ENM) leads to their release into the environment. We reviewed the available literature concerning environmental concentrations of six ENMs (TiO 2 , ZnO, Ag, fullerenes, CNT and CeO 2 ) in surface waters, wastewater treatment plant effluents, biosolids, sediments, soils and air. Presently, a dozen modeling studies provide environmental concentrations for ENM and a handful of analytical works can be used as basis for a preliminary validation. There are still major knowledge gaps (e.g. on ENM production, application and release) that affect the modeled values, but over all an agreement on the order of magnitude of the environmental concentrations can be reached. True validation of the modeled values is difficult because trace analytical methods that are specific for ENM detection and quantification are not available. The modeled and measured results are not always comparable due to the different forms and sizes of particles that these two approaches target. -- Highlights: •Modeled environmental concentrations of engineered nanomaterials are reviewed. •Measured environmental concentrations of engineered nanomaterials are reviewed. •Possible validation of modeled data by measurements is critically evaluated. •Different approaches in modeling and measurement methods complicate validation. -- Modeled and measured environmental concentrations of engineered nanomaterials are reviewed and critically discussed
International Nuclear Information System (INIS)
Strack, O.D.L.
1982-02-01
An analytic model has been developed for two dimensional steady flow through infinite fissured porous media, and is implemented in a computer program. The model is the first, and major, step toward the development of a model with finite boundaries, intended for use as a tool for numerical experiments. These experiments may serve to verify some of the simplifying assumptions made in continuum models and to gain insight in the mechanics of the flow. The model is formulated in terms of complex variables and the analytic functions presented are closed-form expressions obtained from singular Cauchy integrals. An exact solution is given for the case of a single crack in an infinite porous medium. The exact solution is compared with the result obtained by the use of an independent method, which assumes Darcian flow in the crack and models the crack as an inhomogeneity in the permeability, in order to verify the simplifying assumptions. The approximate model is compared with solutions obtained from the above independent method for some cases of intersecting cracks. The agreement is good, provided that a sufficient number of elements are used to model the cracks
One-dimensional Analytical Modelling of Floating Seed Dispersal in Tidal Channels
Shi, W.; Purnama, A.; Shao, D.; Cui, B.; Gao, W.
2017-12-01
Seed dispersal is a primary factor influencing plant community development, and thus plays a critical role in maintaining wetland ecosystem functioning. However, compared with fluvial seed dispersal of riparian plants, dispersal of saltmarsh plant seeds in tidal channels is much less studied due to its complex behavior, and relevant mathematical modelling is particularly lacking. In this study, we developed a one-dimensional advection-dispersion model to explore the patterns of tidal seed dispersal. Oscillatory tidal current and water depth were assumed to represent the tidal effects. An exponential decay coefficient λ was introduced to account for seed deposition and retention. Analytical solution in integral form was derived using Green's function and further evaluated using numerical integration. The developed model was applied to simulate Spartina densiflora seed dispersal in a tidal channel located at the Mad River Slough in North Humboldt Bay, California, USA, to demonstrate its practical applicability. Model predictions agree satisfactorily with field observation and simulation results from Delft3D numerical model. Sensitivity analyses were also conducted to evaluate the effects of varying calibrated parameters on model predictions. The range of the seed dispersion as well as the distribution of the seed concentration were further analyzed through statistical parameters such as centroid displacement and variance of the seed cloud together with seed concentration contours. Implications of the modelling results on tidal marsh restoration and protection, e.g., revegetation through seed addition, were also discussed through scenario analysis. The developed analytical model provides a useful tool for ecological management of tidal marshes.
International Nuclear Information System (INIS)
Hristov, D; Schlosser, J; Bazalova, M; Chen, J
2014-01-01
Purpose: To quantify the effect of ultrasound (US) probe beam attenuation for radiation therapy delivered under real-time US image guidance by means of Monte Carlo (MC) simulations. Methods: MC models of two Philips US probes, an X6-1 matrix-array transducer and a C5-2 curved-array transducer, were built based on their CT images in the EGSnrc BEAMnrc and DOSXYZnrc codes. Due to the metal parts, the probes were scanned in a Tomotherapy machine with a 3.5 MV beam. Mass densities in the probes were assigned based on an electron density calibration phantom consisting of cylinders with mass densities between 0.2–8.0 g/cm 3 . Beam attenuation due to the probes was measured in a solid water phantom for a 6 MV and 15 MV 15x15 cm 2 beam delivered on a Varian Trilogy linear accelerator. The dose was measured with the PTW-729 ionization chamber array at two depths and compared to MC simulations. The extreme case beam attenuation expected in robotic US image guided radiotherapy for probes in upright position was quantified by means of MC simulations. Results: The 3.5 MV CT number to mass density calibration curve was found to be linear with R 2 > 0.99. The maximum mass densities were 4.6 and 4.2 g/cm 3 in the C5-2 and X6-1 probe, respectively. Gamma analysis of the simulated and measured doses revealed that over 98% of measurement points passed the 3%/3mm criteria for both probes and measurement depths. The extreme attenuation for probes in upright position was found to be 25% and 31% for the C5-2 and X6-1 probe, respectively, for both 6 and 15 MV beams at 10 cm depth. Conclusion: MC models of two US probes used for real-time image guidance during radiotherapy have been built. As a Result, radiotherapy treatment planning with the imaging probes in place can now be performed. J Schlosser is an employee of SoniTrack Systems, Inc. D Hristov has financial interest in SoniTrack Systems, Inc
Probing the interaction of brain fatty acid binding protein (B-FABP with model membranes.
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Fábio Dyszy
Full Text Available Brain fatty acid-binding protein (B-FABP interacts with biological membranes and delivers polyunsaturated fatty acids (FAs via a collisional mechanism. The binding of FAs in the protein and the interaction with membranes involve a motif called "portal region", formed by two small α-helices, A1 and A2, connected by a loop. We used a combination of site-directed mutagenesis and electron spin resonance to probe the changes in the protein and in the membrane model induced by their interaction. Spin labeled B-FABP mutants and lipidic spin probes incorporated into a membrane model confirmed that B-FABP interacts with micelles through the portal region and led to structural changes in the protein as well in the micelles. These changes were greater in the presence of LPG when compared to the LPC models. ESR spectra of B-FABP labeled mutants showed the presence of two groups of residues that responded to the presence of micelles in opposite ways. In the presence of lysophospholipids, group I of residues, whose side chains point outwards from the contact region between the helices, had their mobility decreased in an environment of lower polarity when compared to the same residues in solution. The second group, composed by residues with side chains situated at the interface between the α-helices, experienced an increase in mobility in the presence of the model membranes. These modifications in the ESR spectra of B-FABP mutants are compatible with a less ordered structure of the portal region inner residues (group II that is likely to facilitate the delivery of FAs to target membranes. On the other hand, residues in group I and micelle components have their mobilities decreased probably as a result of the formation of a collisional complex. Our results bring new insights for the understanding of the gating and delivery mechanisms of FABPs.
Analytical Performance Modeling and Validation of Intel’s Xeon Phi Architecture
Energy Technology Data Exchange (ETDEWEB)
Chunduri, Sudheer; Balaprakash, Prasanna; Morozov, Vitali; Vishwanath, Venkatram; Kumaran, Kalyan
2017-01-01
Modeling the performance of scientific applications on emerging hardware plays a central role in achieving extreme-scale computing goals. Analytical models that capture the interaction between applications and hardware characteristics are attractive because even a reasonably accurate model can be useful for performance tuning before the hardware is made available. In this paper, we develop a hardware model for Intel’s second-generation Xeon Phi architecture code-named Knights Landing (KNL) for the SKOPE framework. We validate the KNL hardware model by projecting the performance of mini-benchmarks and application kernels. The results show that our KNL model can project the performance with prediction errors of 10% to 20%. The hardware model also provides informative recommendations for code transformations and tuning.
Analytical and Empirical Modeling of Wear and Forces of CBN Tool in Hard Turning - A Review
Patel, Vallabh Dahyabhai; Gandhi, Anishkumar Hasmukhlal
2017-08-01
Machining of steel material having hardness above 45 HRC (Hardness-Rockwell C) is referred as a hard turning. There are numerous models which should be scrutinized and implemented to gain optimum performance of hard turning. Various models in hard turning by cubic boron nitride tool have been reviewed, in attempt to utilize appropriate empirical and analytical models. Validation of steady state flank and crater wear model, Usui's wear model, forces due to oblique cutting theory, extended Lee and Shaffer's force model, chip formation and progressive flank wear have been depicted in this review paper. Effort has been made to understand the relationship between tool wear and tool force based on the different cutting conditions and tool geometries so that appropriate model can be used according to user requirement in hard turning.
New analytical solution for pyle-popovich's peritoneal dialysis model
Energy Technology Data Exchange (ETDEWEB)
Hamada, Hiroyuki; Sakiyama, Ryoichi; Okamoto, Masahiro; Tojo, Kakuji [Kyushi Institute of Technology, Fukuoka (Japan); Yamashita, Akihiro [Shonan Institute of Technology, Kanagwa (Japan)
1999-08-01
Continuous Ambulatory Peritoneal Dialysis (CAPD) is one of the standard treatments for kidney disease patients. A washing solution, called dialysate, is put into the peritoneal cavity to remove waste products and excess amounts of water in CAPD. The dialysate is exchanged four to five times a day by the patient. However, it is not easy to prescribe CAPD therapy, which may have precluded popularization of CAPD therapy. Popovich et al. constructed a mathematical model (P-P model) that applies to the prescription of the treatment schedule. It requires, however, a number of iterative calculations to obtain a exact numerical solution because the model is a set of nonlinear simultaneous ordinary differential equations. In this paper, the authors derived a new approximated analytical solution by employing a time-discrete technique, assuming all the parameters to be constant within each piecewise period of time for the P-P model. We have also described an algorithm of a numerical calculation with the new solution for clinical use with another analytical solution (Vonesh's solution). The new analytical solution consists of a forward solution (FW solution). The new analytical solution consists of a forward solution (FW solution), that is the solution for the plasma and dialysate concentrations from t{sub i} to t{sub i+1}(t{sub i}
Analyticity of effective coupling and propagators in massless models of quantum field theory
International Nuclear Information System (INIS)
Oehme, R.
1982-01-01
For massless models of quantum field theory, some general theorems are proved concerning the analytic continuation of the renormalization group functions as well as the effective coupling and the propagators. Starting points are analytic properties of the effective coupling and the propagators in the momentum variable k 2 , which can be converted into analyticity of β- and γ-functions in the coupling parameter lambda. It is shown that the β-function can have branch point singularities related to stationary points of the effective coupling as a function of k 2 . The type of these singularities of β(lambda) can be determined explicitly. Examples of possible physical interest are extremal values of the effective coupling at space-like points in the momentum variable, as well as complex conjugate stationary points close to the real k 2 -axis. The latter may be related to the sudden transition between weak and strong coupling regimes of the system. Finally, for the effective coupling and for the propagators, the analytic continuation in both variables k 2 and lambda is discussed. (orig.)
A semi-analytical method for simulating matrix diffusion in numerical transport models.
Falta, Ronald W; Wang, Wenwen
2017-02-01
A semi-analytical approximation for transient matrix diffusion is developed for use in numerical contaminant transport simulators. This method is an adaptation and extension of the heat conduction method of Vinsome and Westerveld (1980) used to simulate heat losses during thermally enhanced oil recovery. The semi-analytical method is used in place of discretization of the low permeability materials, and it represents the concentration profile in the low permeability materials with a fitting function that is adjusted in each element at each time-step. The resulting matrix diffusion fluxes are added to the numerical model as linear concentration-dependent source/sink terms. Since only the high permeability zones need to be discretized, the numerical formulation is extremely efficient compared to traditional approaches that require discretization of both the high and low permeability zones. The semi-analytical method compares favorably with the analytical solution for transient one-dimensional diffusion with first order decay, with a two-layer aquifer/aquitard solution, with the solution for transport in a fracture with matrix diffusion and decay, and with a fully numerical solution for transport in a thin sand zone bounded by clay with variable decay rates. Copyright © 2017 Elsevier B.V. All rights reserved.
Manufactured analytical solutions for isothermal full-Stokes ice sheet models
Directory of Open Access Journals (Sweden)
A. Sargent
2010-08-01
Full Text Available We present the detailed construction of a manufactured analytical solution to time-dependent and steady-state isothermal full-Stokes ice sheet problems. The solutions are constructed for two-dimensional flowline and three-dimensional full-Stokes ice sheet models with variable viscosity. The construction is done by choosing for the specified ice surface and bed a velocity distribution that satisfies both mass conservation and the kinematic boundary conditions. Then a compensatory stress term in the conservation of momentum equations and their boundary conditions is calculated to make the chosen velocity distributions as well as the chosen pressure field into exact solutions. By substituting different ice surface and bed geometry formulas into the derived solution formulas, analytical solutions for different geometries can be constructed.
The boundary conditions can be specified as essential Dirichlet conditions or as periodic boundary conditions. By changing a parameter value, the analytical solutions allow investigation of algorithms for a different range of aspect ratios as well as for different, frozen or sliding, basal conditions. The analytical solutions can also be used to estimate the numerical error of the method in the case when the effects of the boundary conditions are eliminated, that is, when the exact solution values are specified as inflow and outflow boundary conditions.
Optimization Model for Uncertain Statistics Based on an Analytic Hierarchy Process
Directory of Open Access Journals (Sweden)
Yongchao Hou
2014-01-01
Full Text Available Uncertain statistics is a methodology for collecting and interpreting the expert’s experimental data by uncertainty theory. In order to estimate uncertainty distributions, an optimization model based on analytic hierarchy process (AHP and interpolation method is proposed in this paper. In addition, the principle of least squares method is presented to estimate uncertainty distributions with known functional form. Finally, the effectiveness of this method is illustrated by an example.
What makes us think? A three-stage dual-process model of analytic engagement.
Pennycook, Gordon; Fugelsang, Jonathan A; Koehler, Derek J
2015-08-01
The distinction between intuitive and analytic thinking is common in psychology. However, while often being quite clear on the characteristics of the two processes ('Type 1' processes are fast, autonomous, intuitive, etc. and 'Type 2' processes are slow, deliberative, analytic, etc.), dual-process theorists have been heavily criticized for being unclear on the factors that determine when an individual will think analytically or rely on their intuition. We address this issue by introducing a three-stage model that elucidates the bottom-up factors that cause individuals to engage Type 2 processing. According to the model, multiple Type 1 processes may be cued by a stimulus (Stage 1), leading to the potential for conflict detection (Stage 2). If successful, conflict detection leads to Type 2 processing (Stage 3), which may take the form of rationalization (i.e., the Type 1 output is verified post hoc) or decoupling (i.e., the Type 1 output is falsified). We tested key aspects of the model using a novel base-rate task where stereotypes and base-rate probabilities cued the same (non-conflict problems) or different (conflict problems) responses about group membership. Our results support two key predictions derived from the model: (1) conflict detection and decoupling are dissociable sources of Type 2 processing and (2) conflict detection sometimes fails. We argue that considering the potential stages of reasoning allows us to distinguish early (conflict detection) and late (decoupling) sources of analytic thought. Errors may occur at both stages and, as a consequence, bias arises from both conflict monitoring and decoupling failures. Copyright © 2015 Elsevier Inc. All rights reserved.
Analytical modeling of core hydraulics and flow management in breeder reactors
International Nuclear Information System (INIS)
Carelli, M.D.; Willis, J.M.
1979-01-01
An analytical model representing the hydraulic behavior of the primary system of fast breeder nuclear reactors is discussed. A computer code capable of detailing the core flow distribution and characterizing the flow and pressure drop in each reactor component is presented. Application of this method to the reactor core thermal-hydraulic design has allowed optimization of the flow management with consequent upgrading in performance, reduction of unnecessary conservatism and very substantial cost savings. Typical quantitative examples are presented
Analytical results for entanglement in the five-qubit anisotropic Heisenberg model
International Nuclear Information System (INIS)
Wang Xiaoguang
2004-01-01
We solve the eigenvalue problem of the five-qubit anisotropic Heisenberg model, without use of Bethe's ansatz, and give analytical results for entanglement and mixedness of two nearest-neighbor qubits. The entanglement takes its maximum at Δ=1 (Δ>1) for the case of zero (finite) temperature with Δ being the anisotropic parameter. In contrast, the mixedness takes its minimum at Δ=1 (Δ>1) for the case of zero (finite) temperature
Analytical Model of Inlet Growth and Equilibrium Cross-Sectional Area
2016-04-01
ERDC/CHL CHETN-IV-107 April 2016 Approved for public release; distribution is unlimited. Analytical Model of Inlet Growth and Equilibrium Cross...encompass a broader range of theoretical alternatives to investigate inlet stability. The quadratic formula provides quantitative estimates of equilibrium ...rework sediment. Escoffier (1940) theorized that stable inlets form when the maximum flow equals an equilibrium value based on sediment transport
Directory of Open Access Journals (Sweden)
Xiaocong He
2014-01-01
Full Text Available An analytical model for predicting the stress distributions within single-lap adhesively bonded beams under tension is presented in this paper. By combining the governing equations of each adherend with the joint kinematics, the overall system of governing equations can be obtained. Both the adherends and the adhesive are assumed to be under plane strain condition. With suitable boundary conditions, the stress distribution of the adhesive in the longitudinal direction is determined.
Probing the topological properties of complex networks modeling short written texts.
Directory of Open Access Journals (Sweden)
Diego R Amancio
Full Text Available In recent years, graph theory has been widely employed to probe several language properties. More specifically, the so-called word adjacency model has been proven useful for tackling several practical problems, especially those relying on textual stylistic analysis. The most common approach to treat texts as networks has simply considered either large pieces of texts or entire books. This approach has certainly worked well-many informative discoveries have been made this way-but it raises an uncomfortable question: could there be important topological patterns in small pieces of texts? To address this problem, the topological properties of subtexts sampled from entire books was probed. Statistical analyses performed on a dataset comprising 50 novels revealed that most of the traditional topological measurements are stable for short subtexts. When the performance of the authorship recognition task was analyzed, it was found that a proper sampling yields a discriminability similar to the one found with full texts. Surprisingly, the support vector machine classification based on the characterization of short texts outperformed the one performed with entire books. These findings suggest that a local topological analysis of large documents might improve its global characterization. Most importantly, it was verified, as a proof of principle, that short texts can be analyzed with the methods and concepts of complex networks. As a consequence, the techniques described here can be extended in a straightforward fashion to analyze texts as time-varying complex networks.
Modeling the Proton Radiation Belt With Van Allen Probes Relativistic Electron-Proton Telescope Data
Selesnick, R. S.; Baker, D. N.; Kanekal, S. G.; Hoxie, V. C.; Li, X.
2018-01-01
An empirical model of the proton radiation belt is constructed from data taken during 2013-2017 by the Relativistic Electron-Proton Telescopes on the Van Allen Probes satellites. The model intensity is a function of time, kinetic energy in the range 18-600 MeV, equatorial pitch angle, and L shell of proton guiding centers. Data are selected, on the basis of energy deposits in each of the nine silicon detectors, to reduce background caused by hard proton energy spectra at low L. Instrument response functions are computed by Monte Carlo integration, using simulated proton paths through a simplified structural model, to account for energy loss in shielding material for protons outside the nominal field of view. Overlap of energy channels, their wide angular response, and changing satellite orientation require the model dependencies on all three independent variables be determined simultaneously. This is done by least squares minimization with a customized steepest descent algorithm. Model uncertainty accounts for statistical data error and systematic error in the simulated instrument response. A proton energy spectrum is also computed from data taken during the 8 January 2014 solar event, to illustrate methods for the simpler case of an isotropic and homogeneous model distribution. Radiation belt and solar proton results are compared to intensities computed with a simplified, on-axis response that can provide a good approximation under limited circumstances.
Concu, Riccardo; Kleandrova, Valeria V; Speck-Planche, Alejandro; Cordeiro, M Natália D S
2017-09-01
Nanoparticles (NPs) are part of our daily life, having a wide range of applications in engineering, physics, chemistry, and biomedicine. However, there are serious concerns regarding the harmful effects that NPs can cause to the different biological systems and their ecosystems. Toxicity testing is an essential step for assessing the potential risks of the NPs, but the experimental assays are often very expensive and usually too slow to flag the number of NPs that may cause adverse effects. In silico models centered on quantitative structure-activity/toxicity relationships (QSAR/QSTR) are alternative tools that have become valuable supports to risk assessment, rationalizing the search for safer NPs. In this work, we develop a unified QSTR-perturbation model based on artificial neural networks, aimed at simultaneously predicting general toxicity profiles of NPs under diverse experimental conditions. The model is derived from 54,371 NP-NP pair cases generated by applying the perturbation theory to a set of 260 unique NPs, and showed an accuracy higher than 97% in both training and validation sets. Physicochemical interpretation of the different descriptors in the model are additionally provided. The QSTR-perturbation model is then employed to predict the toxic effects of several NPs not included in the original dataset. The theoretical results obtained for this independent set are strongly consistent with the experimental evidence found in the literature, suggesting that the present QSTR-perturbation model can be viewed as a promising and reliable computational tool for probing the toxicity of NPs.
Justh, Hilary L.; Justus, Carl G.
2008-01-01
The Mars Global Reference Atmospheric Model (Mars-GRAM 2005) is an engineering-level atmospheric model widely used for diverse mission applications. An overview is presented of Mars-GRAM 2005 and its new features. The "auxiliary profile" option is one new feature of Mars-GRAM 2005. This option uses an input file of temperature and density versus altitude to replace the mean atmospheric values from Mars-GRAM's conventional (General Circulation Model) climatology. Any source of data or alternate model output can be used to generate an auxiliary profile. Auxiliary profiles for this study were produced from mesoscale model output (Southwest Research Institute's Mars Regional Atmospheric Modeling System (MRAMS) model and Oregon State University's Mars mesoscale model (MMM5) model) and a global Thermal Emission Spectrometer (TES) database. The global TES database has been specifically generated for purposes of making Mars-GRAM auxiliary profiles. This data base contains averages and standard deviations of temperature, density, and thermal wind components, averaged over 5-by-5 degree latitude-longitude bins and 15 degree Ls bins, for each of three Mars years of TES nadir data. The Mars Science Laboratory (MSL) sites are used as a sample of how Mars-GRAM' could be a valuable tool for planning of future Mars entry probe missions. Results are presented using auxiliary profiles produced from the mesoscale model output and TES observed data for candidate MSL landing sites. Input parameters rpscale (for density perturbations) and rwscale (for wind perturbations) can be used to "recalibrate" Mars-GRAM perturbation magnitudes to better replicate observed or mesoscale model variability.
A Factor-Analytic Model for Assessing Individual Differences in Response Scale Usage.
Ferrando, Pere J
2014-01-01
This article proposes a factor-analytic model, intended for graded-response or continuous-response personality and attitude items, which includes an additional multiplicative person parameter that models the individual's response mapping process. The model, which is a modification of Spearman's (1904) factor analysis (FA) model, is parameterized as both an FA model and an item response theory (IRT) model and is fully developed to the extent that it can be used in applications. Procedures for (a) calibrating the items and assessing data fit, (b) obtaining individual estimates of both person parameters, (c) determining measurement precision, and (d) assessing differential predictability are proposed and discussed. The potential advantages of the proposal, its practical relevance, and its relations with other approaches are also discussed. Its functioning is assessed with a simulation study and 3 empirical examples in the personality domain.
Analytical Modelling of Wireless Power Transfer (WPT) Systems for Electric Vehicle Application
Energy Technology Data Exchange (ETDEWEB)
Chinthavali, Madhu Sudhan [ORNL; Campbell, Steven L [ORNL
2016-01-01
This paper presents an analytical model for wireless power transfer system used in electric vehicle application. The equivalent circuit model for each major component of the system is described, including the input voltage source, resonant network, transformer, nonlinear diode rectifier load, etc. Based on the circuit model, the primary side compensation capacitance, equivalent input impedance, active / reactive power are calculated, which provides a guideline for parameter selection. Moreover, the voltage gain curve from dc output to dc input is derived as well. A hardware prototype with series-parallel resonant stage is built to verify the developed model. The experimental results from the hardware are compared with the model predicted results to show the validity of the model.
TU-F-17A-03: An Analytical Respiratory Perturbation Model for Lung Motion Prediction
Energy Technology Data Exchange (ETDEWEB)
Li, G; Yuan, A [Memorial Sloan Kettering Cancer Center, New York, NY (United States); Wei, J [City College of New York, New York, NY (United States)
2014-06-15
Purpose: Breathing irregularity is common, causing unreliable prediction in tumor motion for correlation-based surrogates. Both tidal volume (TV) and breathing pattern (BP=ΔVthorax/TV, where TV=ΔVthorax+ΔVabdomen) affect lung motion in anterior-posterior and superior-inferior directions. We developed a novel respiratory motion perturbation (RMP) model in analytical form to account for changes in TV and BP in motion prediction from simulation to treatment. Methods: The RMP model is an analytical function of patient-specific anatomic and physiologic parameters. It contains a base-motion trajectory d(x,y,z) derived from a 4-dimensional computed tomography (4DCT) at simulation and a perturbation term Δd(ΔTV,ΔBP) accounting for deviation at treatment from simulation. The perturbation is dependent on tumor-specific location and patient-specific anatomy. Eleven patients with simulation and treatment 4DCT images were used to assess the RMP method in motion prediction from 4DCT1 to 4DCT2, and vice versa. For each patient, ten motion trajectories of corresponding points in the lower lobes were measured in both 4DCTs: one served as the base-motion trajectory and the other as the ground truth for comparison. In total, 220 motion trajectory predictions were assessed. The motion discrepancy between two 4DCTs for each patient served as a control. An established 5D motion model was used for comparison. Results: The average absolute error of RMP model prediction in superior-inferior direction is 1.6±1.8 mm, similar to 1.7±1.6 mm from the 5D model (p=0.98). Some uncertainty is associated with limited spatial resolution (2.5mm slice thickness) and temporal resolution (10-phases). Non-corrected motion discrepancy between two 4DCTs is 2.6±2.7mm, with the maximum of ±20mm, and correction is necessary (p=0.01). Conclusion: The analytical motion model predicts lung motion with accuracy similar to the 5D model. The analytical model is based on physical relationships, requires no
DEFF Research Database (Denmark)
Duvaa, Uffe; Ørngreen, Rikke; Weinkouff, Anne-Gitte
2012-01-01
Mobile probing is a method, which has been developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time...... and space). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings...... point to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face...
DEFF Research Database (Denmark)
Duvaa, Uffe; Ørngreen, Rikke; Weinkouff Mathiasen, Anne-Gitte
2013-01-01
Mobile probing is a method, developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time and space......). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings point...... to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face). The development...
Modelling and analytic studies of sheared flow effects on tearing modes
Chandra, D.; Thyagaraja, A.; Sen, A.; Ham, C. J.; Hender, T. C.; Hastie, R. J.; Connor, J. W.; Kaw, P.; Mendonca, J.
2015-05-01
The effects of flow shear on the stability of a (2,1) tearing mode are examined using numerical and analytic studies on a number of model systems. For a cylindrical reduced magnetohydrodynamic (MHD) model, linear computations using the CUTIE code show that sheared axial flows have a destabilizing effect, while sheared poloidal flows tend to reduce the growth rate of the mode. These effects are independent of the direction of the flow. For helical flows the sign of the shear in the flow matters. This symmetry breaking is also seen in the nonlinear regime where the island saturation level is found to depend on the sign of the flows. In the absence of flow, the CUTIE simulations show that the linear mode is more stable in a two fluid as compared to a single fluid model. However, in the presence of sheared axial flows a negative sheared flow is more destabilizing while a positive sheared flow is more stabilizing, compared to the single fluid model. In contrast to the cylindrical model, simulations in a toroidal model, using the MHD code NEAR, always show a stabilizing effect in the presence of a sheared toroidal flow. This is understood analytically in terms of a flow induced ‘Shafranov’ like shift in the profiles of the equilibrium current that results in a stabilizing change in Δ‧ and the saturated island size.
International Nuclear Information System (INIS)
Czubek, J.A.; Lenda, A.
1979-01-01
The minimum dimensions have been calculated assuring 91, 96 and 98 % of the probe response in respect to the infinite medium. The models are of cylindrical form, the probe (source-to-detector distance equal to 60 or 90 cm) being placed on the model axis, symmetrically with respect to the two end-faces. All the models are ''embedded'' in various media, such as: air, sand of 40% porosity and completely saturated with water, sand of 30 % porosity and of moisture content equal to 10 %, and water. The models are of three types of material: sandstone, limestone and dolomite, with various porosities, ranging from 0 to 100 %. The probe response is due to gamma rays arising from the radiativecapture of thermal neutrons. The calculations were carried out for the highest energy line of gamma rays arising in given litology. Gamma-ray flux from the neutron radiative capture has been calculated versus rock porosity and model dimensions and radiation migration lengths determined for given litologies. The minimum dimensions of cylindrical models are given as functions of: porosity, probe length (source-to-detector distance) lithology of model and type of medium surrounding our model. (author)
An analytic model of the shear modulus at all densities and temperatures
Burakovsky, L.; Greeff, C. W.; Preston, D. L.
2002-01-01
An analytic model of the shear modulus applicable at temperatures up to melt and at all densities is presented. It is based in part on a relation between the melting temperature and the shear modulus at melt. Experimental data on argon are shown to agree with this relation to within 1%. The model of the shear modulus involves seven parameters, all of which can be determined from zero-pressure experimental data. We obtain the values of these parameters for 11 elemental solids. Both the experim...
The analytical calibration model of temperature effects on a silicon piezoresistive pressure sensor
Directory of Open Access Journals (Sweden)
Meng Nie
2017-03-01
Full Text Available Presently, piezoresistive pressure sensors are highly demanded for using in various microelectronic devices. The electrical behavior of these pressure sensor is mainly dependent on the temperature gradient. In this paper, various factors,which includes effect of temperature, doping concentration on the pressure sensitive resistance, package stress, and temperature on the Young’s modulus etc., are responsible for the temperature drift of the pressure sensor are analyzed. Based on the above analysis, an analytical calibration model of the output voltage of the sensor is proposed and the experimental data is validated through a suitable model.
Analytical Model based on Green Criteria for Optical Backbone Network Interconnection
DEFF Research Database (Denmark)
Gutierrez Lopez, Jose Manuel; Riaz, M. Tahir; Pedersen, Jens Myrup
2011-01-01
to the evaluation of the environmental impact of networks from physical interconnection point of view. Networks deployment, usage, and disposal are analyzed as contributing elements to ICT’s (Information and Communications Technology) CO2 emissions. This paper presents an analytical model for evaluating...... for backbone’s interconnection, since minimization of CO2 emissions is becoming an important factor. In addition, two case studies are presented to illustrate the use and application of this model, and the need for de facto and international standards to reduce CO2 emissions through good network planning....
Directory of Open Access Journals (Sweden)
Michael Callaghan
2018-02-01
Full Text Available Serious Games (SG have been shown to have instructional potential and a number of formal models, frameworks and methodologies have emerged to support their design and analysis. The Activity Theory-based Model of Serious Games (ATMSG facilitates a systematic and detailed representation of educational SG describing how game elements are connected together to contribute to pedagogical goals. This paper proposes and presents an extension to the ATMSG framework to facilitate the identification, selection and integration of analytics into serious games. A practical example of the approach in use in the analysis and design phase of a SG for engineering is demonstrated.
Zeng, Shihao; Chen, Manna; Zhang, Ting; Hu, Wei; Guo, Qi; Lu, Daquan
2018-01-01
We illuminate an analytical model of soliton interactions in lead glass by analogizing to a gravitational force system. The orbits of spiraling solitons under a long-range interaction are given explicitly and demonstrated to follow Newton's second law of motion and the Binet equation by numerical simulations. The condition for circular orbits is obtained and the oscillating orbits are proved not to be closed. We prove the analogy between the nonlocal nonlinear optical system and gravitational system and specify the quantitative relation of the quantity between the two models.
An analytical model for force prediction in ball nose micro milling of inclined surfaces
DEFF Research Database (Denmark)
Bissacco, Giuliano; Hansen, Hans Nørgaard; De Chiffre, Leonardo
2010-01-01
Ball nose micro milling is a key process for the generation of free form surfaces and inclined surfaces often present in mould inserts for micro replication. This paper presents a new cutting force model for ball nose micro milling that is capable of taking into account the effect of the edge rad...... radius and the effect of the surface topography due to the previous milling passes. The model is completely analytical can be applied to ball end micro milling of slanted surfaces for any value of the surface inclination angle relative to the tool axis....
International Nuclear Information System (INIS)
Wang, Lei; Wang, Xiaodong
2014-01-01
Resulting from the nature of anisotropy of coal media, it is a meaningful work to evaluate pressure transient behavior and flow characteristics within coals. In this article, a complete analytical model called the elliptical flow model is established by combining the theory of elliptical flow in anisotropic media and Fick's laws about the diffusion of coalbed methane. To investigate pressure transient behavior, analytical solutions were first obtained through introducing a series of special functions (Mathieu functions), which are extremely complex and are hard to calculate. Thus, a computer program was developed to establish type curves, on which the effects of the parameters, including anisotropy coefficient, storage coefficient, transfer coefficient and rate constant, were analyzed in detail. Calculative results show that the existence of anisotropy would cause great pressure depletion. To validate new analytical solutions, previous results were used to compare with the new results. It is found that a better agreement between the solutions obtained in this work and the literature was achieved. Finally, a case study is used to explain the effects of the parameters, including rock total compressibility coefficient, coal medium porosity and anisotropic permeability, sorption time constant, Langmuir volume and fluid viscosity, on bottom-hole pressure behavior. It is necessary to coordinate these parameters so as to reduce the pressure depletion. (paper)
Directory of Open Access Journals (Sweden)
Yan Peng
2017-02-01
Full Text Available We investigate holographic phase transitions with dark matter sector in the AdS soliton background away from the probe limit. In cases of weak backreaction, we find that the larger coupling parameter α makes the gap of condensation shallower and the critical chemical potential keeps as a constant. In contrast, for very heavy backreaction, the dark matter sector could affect the critical chemical potential and the order of phase transitions. We also find the jump of the holographic topological entanglement entropy corresponds to a first order transition between superconducting states in this model with dark matter sector. More importantly, for certain sets of parameters, we observe novel phenomenon of retrograde condensation. In a word, the dark matter sector provides richer physics in the phase structure and the holographic superconductor properties are helpful in understanding dark matter.
International Nuclear Information System (INIS)
Peng, Yan; Pan, Qiyuan; Liu, Yunqi
2017-01-01
We investigate holographic phase transitions with dark matter sector in the AdS soliton background away from the probe limit. In cases of weak backreaction, we find that the larger coupling parameter α makes the gap of condensation shallower and the critical chemical potential keeps as a constant. In contrast, for very heavy backreaction, the dark matter sector could affect the critical chemical potential and the order of phase transitions. We also find the jump of the holographic topological entanglement entropy corresponds to a first order transition between superconducting states in this model with dark matter sector. More importantly, for certain sets of parameters, we observe novel phenomenon of retrograde condensation. In a word, the dark matter sector provides richer physics in the phase structure and the holographic superconductor properties are helpful in understanding dark matter.
Energy Technology Data Exchange (ETDEWEB)
Peng, Yan, E-mail: yanpengphy@163.com [School of Mathematical Sciences, Qufu Normal University, Qufu, Shandong 273165 (China); School of Mathematics and Computer Science, Shaanxi Sci-Tech University, Hanzhong, Shaanxi 723000 (China); Pan, Qiyuan, E-mail: panqiyuan@126.com [Department of Physics, Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, Hunan Normal University, Changsha, Hunan 410081 (China); Liu, Yunqi, E-mail: liuyunqi@hust.edu.cn [School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)
2017-02-15
We investigate holographic phase transitions with dark matter sector in the AdS soliton background away from the probe limit. In cases of weak backreaction, we find that the larger coupling parameter α makes the gap of condensation shallower and the critical chemical potential keeps as a constant. In contrast, for very heavy backreaction, the dark matter sector could affect the critical chemical potential and the order of phase transitions. We also find the jump of the holographic topological entanglement entropy corresponds to a first order transition between superconducting states in this model with dark matter sector. More importantly, for certain sets of parameters, we observe novel phenomenon of retrograde condensation. In a word, the dark matter sector provides richer physics in the phase structure and the holographic superconductor properties are helpful in understanding dark matter.
Li-ion battery ageing model parameter: SEI layer analysis using magnetic field probing
Directory of Open Access Journals (Sweden)
Parmender Singh
2018-02-01
Full Text Available With the growing usage of lithium-ion (Li-ion batteries in various applications from stationary applications to automotive industries, their ageing mechanism and its influencing factors have become a big concern today. Ageing may be defined as deterioration in the performance of the battery due to irreversible physical and chemical changes like internal resistance rise, electrolyte decompositions, electrodes cracking and solid electrolyte interphase (SEI modification/growth. The aim of this research article is to study and analyse the behaviour of SEI layer growth at the anode using a novel non-invasive magnetic field probing (MFP. A 3-d model based upon well-known John Newman’s pseudo 2-d approach has been developed in COMSOL Multiphysics®. It is observed that the magnetic field response (MFR is inversely related to SEI growth. Anode’s state of charge (SoC response with SEI layer and MFR is also studied.
Evaluation of simplified analytical models for CO2 plume movement and pressure buildup
Oruganti, Y.; Mishra, S.
2011-12-01
CO2 injection into the sub-surface is emerging as a viable technology for reducing anthropogenic CO2 emissions into the atmosphere. When large amounts of CO2 are sequestered, pressure buildup is an associated risk, along with plume movement beyond the injected domain. In this context, simple modeling tools become valuable assets in preliminary CO2 injection project screening and implementation phases. This study presents an evaluation of two commonly used simplified analytical models for plume movement and pressure buildup, (1) the sharp interface model of Nordbotten et al. (2005), and the corresponding pressure distribution solution of Mathias et al. (2008), and (2) the 3-region model of Burton et al. (2008) based on fractional flow and steady-state pressure gradient considerations. The three-region model of Burton et al. assumes a constant pressure outer boundary. In this study, we incorporate the radius of investigation of the pressure front as the transient pressure boundary, in order to represent an infinite-acting system. The sharp-interface model also assumes the system to be infinite-acting. Temperature and pressure conditions used in these models correspond to the "warm, shallow" and "cold, deep" aquifer conditions as defined by Nordbotten et al. The saturation and pressure profiles as well as injection-well pressure buildup predicted by the analytical models are compared with those from the numerical simulator STOMP in order to provide a verification of the simplified modeling assumptions. Both the STOMP results and the three-region model show two sharp fronts (the drying and two-phase fronts), and a good match is obtained between the front positions at any time. For the sharp interface model, the vertically averaged gas saturation does not exhibit two sharp fronts as seen in the STOMP simulations, but shows a gradual change in saturation with radial distance over the two-phase region. The pressure profiles from STOMP and the analytical model are
Analytical and Finite Element Modeling of Nanomembranes for Miniaturized, Continuous Hemodialysis
Directory of Open Access Journals (Sweden)
Tucker Burgin
2015-12-01
Full Text Available Hemodialysis involves large, periodic treatment doses using large-area membranes. If the permeability of dialysis membranes could be increased, it would reduce the necessary dialyzer size and could enable a wearable device that administers a continuous, low dose treatment of chronic kidney disease. This paper explores the application of ultrathin silicon membranes to this purpose, by way of analytical and finite element models of diffusive and convective transport of plasma solutes during hemodialysis, which we show to be predictive of experimental results. A proof-of-concept miniature nanomembrane dialyzer design is then proposed and analytically predicted to clear uremic toxins at near-ideal levels, as measured by several markers of dialysis adequacy. This work suggests the feasibility of miniature nanomembrane-based dialyzers that achieve therapeutic levels of uremic toxin clearance for patients with kidney failure.
An analytic network process-based multicriteria decision making model for a reverse supply chain
DEFF Research Database (Denmark)
Govindan, Kannan; Sarkis, J.; Palaniappan, M.
2013-01-01
Reverse logistics has emerged as an important dimension for organizations to build their strategic advantage. Part of this effort relies on potentially outsourcing these activities. With this competitive issue in mind, this paper presents a multistep process to select a third-party reverse logistic...... provider (3PRLP). Criteria for evaluation are drawn from the literature and practical input from experts and decision makers within a case company. The process requires that an initial screening of criteria is completed through the analytical hierarchy process. The second stage of the process, 3PRLP...... selection, is completed using the analytic network process. An illustrative example is provided to demonstrate the solutions obtained by the proposed process within an automobile case company. A sensitivity analysis is also provided for a robustness check. The results obtained from the proposed model...
International Nuclear Information System (INIS)
Hu Xia-Rong; Lü Rui
2014-01-01
In this paper, an analytical model for the vertical electric field distribution and optimization of a high voltage-reduced bulk field (REBULF) lateral double-diffused metal—oxide-semiconductor (LDMOS) transistor is presented. The dependences of the breakdown voltage on the buried n-layer depth, thickness, and doping concentration are discussed in detail. The REBULF criterion and the optimal vertical electric field distribution condition are derived on the basis of the optimization of the electric field distribution. The breakdown voltage of the REBULF LDMOS transistor is always higher than that of a single reduced surface field (RESURF) LDMOS transistor, and both analytical and numerical results show that it is better to make a thick n-layer buried deep into the p-substrate. (interdisciplinary physics and related areas of science and technology)
A simple analytical thermo-mechanical model for liquid crystal elastomer bilayer structures
Directory of Open Access Journals (Sweden)
Yun Cui
2018-02-01
Full Text Available The bilayer structure consisting of thermal-responsive liquid crystal elastomers (LCEs and other polymer materials with stretchable heaters has attracted much attention in applications of soft actuators and soft robots due to its ability to generate large deformations when subjected to heat stimuli. A simple analytical thermo-mechanical model, accounting for the non-uniform feature of the temperature/strain distribution along the thickness direction, is established for this type of bilayer structure. The analytical predictions of the temperature and bending curvature radius agree well with finite element analysis and experiments. The influences of the LCE thickness and the heat generation power on the bending deformation of the bilayer structure are fully investigated. It is shown that a thinner LCE layer and a higher heat generation power could yield more bending deformation. These results may help the design of soft actuators and soft robots involving thermal responsive LCEs.
Experiments with More Than One Random Factor: Designs, Analytic Models, and Statistical Power.
Judd, Charles M; Westfall, Jacob; Kenny, David A
2017-01-03
Traditional methods of analyzing data from psychological experiments are based on the assumption that there is a single random factor (normally participants) to which generalization is sought. However, many studies involve at least two random factors (e.g., participants and the targets to which they respond, such as words, pictures, or individuals). The application of traditional analytic methods to the data from such studies can result in serious bias in testing experimental effects. In this review, we develop a comprehensive typology of designs involving two random factors, which may be either crossed or nested, and one fixed factor, condition. We present appropriate linear mixed models for all designs and develop effect size measures. We provide the tools for power estimation for all designs. We then discuss issues of design choice, highlighting power and feasibility considerations. Our goal is to encourage appropriate analytic methods that produce replicable results for studies involving new samples of both participants and targets.
Energy Technology Data Exchange (ETDEWEB)
Niedermayer, U., E-mail: niedermayer@temf.tu-darmstadt.de [Institut für Theorie Elektromagnetischer Felder (TEMF), Technische Universität Darmstadt, Schloßgartenstraße 8, 64289 Darmstadt (Germany); Eidam, L. [Institut für Theorie Elektromagnetischer Felder (TEMF), Technische Universität Darmstadt, Schloßgartenstraße 8, 64289 Darmstadt (Germany); Boine-Frankenheim, O. [Institut für Theorie Elektromagnetischer Felder (TEMF), Technische Universität Darmstadt, Schloßgartenstraße 8, 64289 Darmstadt (Germany); GSI Helmholzzentrum für Schwerionenforschung, Planckstraße 1, 64291 Darmstadt (Germany)
2015-03-11
First, a generalized theoretical approach towards beam coupling impedances and stretched-wire measurements is introduced. Applied to a circular symmetric setup, this approach allows to compare beam and wire impedances. The conversion formulas for TEM scattering parameters from measurements to impedances are thoroughly analyzed and compared to the analytical beam impedance solution. A proof of validity for the distributed impedance formula is given. The interaction of the beam or the TEM wave with dispersive material such as ferrite is discussed. The dependence of the obtained beam impedance on the relativistic velocity β is investigated and found as material property dependent. Second, numerical simulations of wakefields and scattering parameters are compared. The applicability of scattering parameter conversion formulas for finite device length is investigated. Laboratory measurement results for a circularly symmetric test setup, i.e. a ferrite ring, are shown and compared to analytic and numeric models. The optimization of the measurement process and error reduction strategies are discussed.
A Novel Analytical Model for Network-on-Chip using Semi-Markov Process
Directory of Open Access Journals (Sweden)
WANG, J.
2011-02-01
Full Text Available Network-on-Chip (NoC communication architecture is proposed to resolve the bottleneck of Multi-processor communication in a single chip. In this paper, a performance analytical model using Semi-Markov Process (SMP is presented to obtain the NoC performance. More precisely, given the related parameters, SMP is used to describe the behavior of each channel and the header flit routing time on each channel can be calculated by analyzing the SMP. Then, the average packet latency in NoC can be calculated. The accuracy of our model is illustrated through simulation. Indeed, the experimental results show that the proposed model can be used to obtain NoC performance and it performs better than the state-of-art models. Therefore, our model can be used as a useful tool to guide the NoC design process.
An analytical model for predicting transport in a coupled vadose/phreatic system
International Nuclear Information System (INIS)
Tomasko, D.
1997-05-01
A simple analytical model is presented for predicting the transport of a contaminant in both the unsaturated (vadose) and saturated (phreatic) zones following a surficial spill. The model incorporates advection, dispersion, adsorption, and first-order decay in both zones and couples the transport processes at the water table. The governing equation is solved by using the method of Laplace transforms, with numerical inversion of the Laplace space equation for concentration. Because of the complexity of the functional form for the Laplace space solution, a numerical methodology using the real and imaginary parts of a Fourier series was implemented. To reduce conservatism in the model, dilution at the water table was also included. Verification of the model is demonstrated by its ability to reproduce the source history at the surface and to replicate appropriate one-dimensional transport through either the vadose or phreatic zone. Because of its simplicity and lack of detailed input data requirements, the model is recommended for scoping calculations
Human eye analytical and mesh-geometry models for ophthalmic dosimetry using MCNP6
International Nuclear Information System (INIS)
Angelocci, Lucas V.; Fonseca, Gabriel P.; Yoriyaz, Helio
2015-01-01
Eye tumors can be treated with brachytherapy using Co-60 plaques, I-125 seeds, among others materials. The human eye has regions particularly vulnerable to ionizing radiation (e.g. crystalline) and dosimetry for this region must be taken carefully. A mathematical model was proposed in the past [1] for the eye anatomy to be used in Monte Carlo simulations to account for dose distribution in ophthalmic brachytherapy. The model includes the description for internal structures of the eye that were not treated in previous works. The aim of this present work was to develop a new eye model based on the Mesh geometries of the MCNP6 code. The methodology utilized the ABAQUS/CAE (Simulia 3DS) software to build the Mesh geometry. For this work, an ophthalmic applicator containing up to 24 model Amersham 6711 I-125 seeds (Oncoseed) was used, positioned in contact with a generic tumor defined analytically inside the eye. The absorbed dose in eye structures like cornea, sclera, choroid, retina, vitreous body, lens, optical nerve and optical nerve wall were calculated using both models: analytical and MESH. (author)
Can We Practically Bring Physics-based Modeling Into Operational Analytics Tools?
Energy Technology Data Exchange (ETDEWEB)
Granderson, Jessica [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Bonvini, Marco [Whisker Labs, Oakland, CA (United States); Piette, Mary Ann [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Page, Janie [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Lin, Guanjing [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Hu, R. Lilly [Univ. of California, Berkeley, CA (United States)
2017-08-11
We present that analytics software is increasingly used to improve and maintain operational efficiency in commercial buildings. Energy managers, owners, and operators are using a diversity of commercial offerings often referred to as Energy Information Systems, Fault Detection and Diagnostic (FDD) systems, or more broadly Energy Management and Information Systems, to cost-effectively enable savings on the order of ten to twenty percent. Most of these systems use data from meters and sensors, with rule-based and/or data-driven models to characterize system and building behavior. In contrast, physics-based modeling uses first-principles and engineering models (e.g., efficiency curves) to characterize system and building behavior. Historically, these physics-based approaches have been used in the design phase of the building life cycle or in retrofit analyses. Researchers have begun exploring the benefits of integrating physics-based models with operational data analytics tools, bridging the gap between design and operations. In this paper, we detail the development and operator use of a software tool that uses hybrid data-driven and physics-based approaches to cooling plant FDD and optimization. Specifically, we describe the system architecture, models, and FDD and optimization algorithms; advantages and disadvantages with respect to purely data-driven approaches; and practical implications for scaling and replicating these techniques. Finally, we conclude with an evaluation of the future potential for such tools and future research opportunities.
Bilcke, Joke; Beutels, Philippe; Brisson, Marc; Jit, Mark
2011-01-01
Accounting for uncertainty is now a standard part of decision-analytic modeling and is recommended by many health technology agencies and published guidelines. However, the scope of such analyses is often limited, even though techniques have been developed for presenting the effects of methodological, structural, and parameter uncertainty on model results. To help bring these techniques into mainstream use, the authors present a step-by-step guide that offers an integrated approach to account for different kinds of uncertainty in the same model, along with a checklist for assessing the way in which uncertainty has been incorporated. The guide also addresses special situations such as when a source of uncertainty is difficult to parameterize, resources are limited for an ideal exploration of uncertainty, or evidence to inform the model is not available or not reliable. for identifying the sources of uncertainty that influence results most are also described. Besides guiding analysts, the guide and checklist may be useful to decision makers who need to assess how well uncertainty has been accounted for in a decision-analytic model before using the results to make a decision.
Human eye analytical and mesh-geometry models for ophthalmic dosimetry using MCNP6
Energy Technology Data Exchange (ETDEWEB)
Angelocci, Lucas V.; Fonseca, Gabriel P.; Yoriyaz, Helio, E-mail: hyoriyaz@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)
2015-07-01
Eye tumors can be treated with brachytherapy using Co-60 plaques, I-125 seeds, among others materials. The human eye has regions particularly vulnerable to ionizing radiation (e.g. crystalline) and dosimetry for this region must be taken carefully. A mathematical model was proposed in the past [1] for the eye anatomy to be used in Monte Carlo simulations to account for dose distribution in ophthalmic brachytherapy. The model includes the description for internal structures of the eye that were not treated in previous works. The aim of this present work was to develop a new eye model based on the Mesh geometries of the MCNP6 code. The methodology utilized the ABAQUS/CAE (Simulia 3DS) software to build the Mesh geometry. For this work, an ophthalmic applicator containing up to 24 model Amersham 6711 I-125 seeds (Oncoseed) was used, positioned in contact with a generic tumor defined analytically inside the eye. The absorbed dose in eye structures like cornea, sclera, choroid, retina, vitreous body, lens, optical nerve and optical nerve wall were calculated using both models: analytical and MESH. (author)
Analytic modeling of a high temperature thermoelectric module for wireless sensors
Köhler, J. E.; Staaf, L. G. H.; Palmqvist, A. E. C.; Enoksson, P.
2014-11-01
A novel high temperature thermoelectric module with thermoelectric materials never before combined in a module is currently researched. The module placement in the cooling channels of a jet engine where the cold side will be cooled by high flow cooling air (550° C) and the hot side will be at the wall (800° C). The aim of the project is to drastically reduce the length of the wires by replacing wired sensors with wireless sensors and power these (3-10mW) with thermoelectric harvesters. To optimize the design for the temperature range and the environment an analytic model was constructed. Using known models for this purpose was not possible for this project, as many of the models have too many assumptions, e.g. that the temperature gradient is relatively low, that thick electrodes with very low resistance can be used, that the heat transfer through the base plates are perfect or that the aim of the design is to maximize the efficiency. The analytical model in this paper is a combination of several known models with the aim to examine what materials to use in this specific environment to achieve the highest possible specific power (mW/g).
Analytic modeling of a high temperature thermoelectric module for wireless sensors
International Nuclear Information System (INIS)
Köhler, J E; Staaf, L G H; Palmqvist, A E C; Enoksson, P
2014-01-01
A novel high temperature thermoelectric module with thermoelectric materials never before combined in a module is currently researched. The module placement in the cooling channels of a jet engine where the cold side will be cooled by high flow cooling air (550° C) and the hot side will be at the wall (800° C). The aim of the project is to drastically reduce the length of the wires by replacing wired sensors with wireless sensors and power these (3-10mW) with thermoelectric harvesters. To optimize the design for the temperature range and the environment an analytic model was constructed. Using known models for this purpose was not possible for this project, as many of the models have too many assumptions, e.g. that the temperature gradient is relatively low, that thick electrodes with very low resistance can be used, that the heat transfer through the base plates are perfect or that the aim of the design is to maximize the efficiency. The analytical model in this paper is a combination of several known models with the aim to examine what materials to use in this specific environment to achieve the highest possible specific power (mW/g)
A theoretical study of CsI:Tl columnar scintillator image quality parameters by analytical modeling
Energy Technology Data Exchange (ETDEWEB)
Kalyvas, N., E-mail: nkalyvas@teiath.gr; Valais, I.; Michail, C.; Fountos, G.; Kandarakis, I.; Cavouras, D.
2015-04-11
Medical X-ray digital imaging systems such as mammography, radiography and computed tomography (CT), are composed from efficient radiation detectors, which can transform the X-rays to electron signal. Scintillators are materials that emit light when excited by X-rays and incorporated in X-ray medical imaging detectors. Columnar scintillator, like CsI:T1 is very often used for X-ray detection due to its higher performance. The columnar form limits the lateral spread of the optical photons to the scintillator output, thus it demonstrates superior spatial resolution compared to granular scintillators. The aim of this work is to provide an analytical model for calculating the MTF, the DQE and the emission efficiency of a columnar scintillator. The model parameters were validated against published Monte Carlo data. The model was able to predict the overall performance of CsI:Tl scintillators and suggested an optimum thickness of 300 μm for radiography applications. - Highlights: • An analytical model for calculating MTF, DQE and Detector Optical Gain (DOG) of columnar phosphors was developed. • The model was fitted to published efficiency and MTF Monte Carlo data. • A good fit was observed for 300 µm columnar CsI:Tl thickness. • The performance of the 300 µm column thickness CsI:Tl was better in terms of MTF and DOG for radiographic applications.
Otero-Espinar, M. V.; Seoane, L. F.; Nieto, J. J.; Mira, J.
2013-12-01
An in-depth analytic study of a model of language dynamics is presented: a model which tackles the problem of the coexistence of two languages within a closed community of speakers taking into account bilingualism and incorporating a parameter to measure the distance between languages. After previous numerical simulations, the model yielded that coexistence might lead to survival of both languages within monolingual speakers along with a bilingual community or to extinction of the weakest tongue depending on different parameters. In this paper, such study is closed with thorough analytical calculations to settle the results in a robust way and previous results are refined with some modifications. From the present analysis it is possible to almost completely assay the number and nature of the equilibrium points of the model, which depend on its parameters, as well as to build a phase space based on them. Also, we obtain conclusions on the way the languages evolve with time. Our rigorous considerations also suggest ways to further improve the model and facilitate the comparison of its consequences with those from other approaches or with real data.
Numerical-analytical interfacing in two dimensions with applications to modeling NTS seismograms
Energy Technology Data Exchange (ETDEWEB)
Stead, R.J.; Helmberger, D.V.
1988-01-01
A new method for interfacing numerical and integral techniques allows greater flexibility in seismic modeling. Specifically, numerical calculations in laterally varying structure are interfaced with analytic methods that enable propagation to great distances. Such modeling is important for studying situations containing localized complex regions not easily handled by analytic means. The calculations involved are entirely two-dimensional, but the use of an appropriate source in combination with a filter applied to the resulting seismograms produces synthetic seismograms which are point-source responses in three dimensions. The integral technique is called two-dimensional Kirchhoff because its form is similar to the classical three-dimensional Kirchhoff. Data from Yucca Flat at the Nevada Test Site are modeled as a demonstration of the usefulness of the new method. In this application, both local and teleseismic records are modeled simultaneously from the same model with the same finite-difference run. This application indicates the importance of locally scattered Rayleigh waves in the production of teleseismic body-wave complexity and coda.
A Novel, Physics-Based Data Analytics Framework for Reducing Systematic Model Errors
Wu, W.; Liu, Y.; Vandenberghe, F. C.; Knievel, J. C.; Hacker, J.
2015-12-01
Most climate and weather models exhibit systematic biases, such as under predicted diurnal temperatures in the WRF (Weather Research and Forecasting) model. General approaches to alleviate the systematic biases include improving model physics and numerics, improving data assimilation, and bias correction through post-processing. In this study, we developed a novel, physics-based data analytics framework in post processing by taking advantage of ever-growing high-resolution (spatial and temporal) observational and modeling data. In the framework, a spatiotemporal PCA (Principal Component Analysis) is first applied on the observational data to filter out noise and information on scales that a model may not be able to resolve. The filtered observations are then used to establish regression relationships with archived model forecasts in the same spatiotemporal domain. The regressions along with the model forecasts predict the projected observations in the forecasting period. The pre-regression PCA procedure strengthens regressions, and enhances predictive skills. We then combine the projected observations with the past observations to apply PCA iteratively to derive the final forecasts. This post-regression PCA reconstructs variances and scales of information that are lost in the regression. The framework was examined and validated with 24 days of 5-minute observational data and archives from the WRF model at 27 stations near Dugway Proving Ground, Utah. The validation shows significant bias reduction in the diurnal cycle of predicted surface air temperature compared to the direct output from the WRF model. Additionally, unlike other post-processing bias correction schemes, the data analytics framework does not require long-term historic data and model archives. A week or two of the data is enough to take into account changes in weather regimes. The program, written in python, is also computationally efficient.
DEFF Research Database (Denmark)
Gaididei, Yuri Borisovich; Berkemer, Rainer; Caputo, Jean Guy
2009-01-01
are found analytically. Their velocity and amplitude are determined from a perturbation approach based on collective coordinates with the discrete modified Korteweg-de Vries equation as the zero order equation. This contains the standard OV model as a special case. The analytical results are in excellent...
Starn, J. J.
2013-12-01
Particle tracking often is used to generate particle-age distributions that are used as impulse-response functions in convolution. A typical application is to produce groundwater solute breakthrough curves (BTC) at endpoint receptors such as pumping wells or streams. The commonly used semi-analytical particle-tracking algorithm based on the assumption of linear velocity gradients between opposing cell faces is computationally very fast when used in combination with finite-difference models. However, large gradients near pumping wells in regional-scale groundwater-flow models often are not well represented because of cell-size limitations. This leads to inaccurate velocity fields, especially at weak sinks. Accurate analytical solutions for velocity near a pumping well are available, and various boundary conditions can be imposed using image-well theory. Python can be used to embed these solutions into existing semi-analytical particle-tracking codes, thereby maintaining the integrity and quality-assurance of the existing code. Python (and associated scientific computational packages NumPy, SciPy, and Matplotlib) is an effective tool because of its wide ranging capability. Python text processing allows complex and database-like manipulation of model input and output files, including binary and HDF5 files. High-level functions in the language include ODE solvers to solve first-order particle-location ODEs, Gaussian kernel density estimation to compute smooth particle-age distributions, and convolution. The highly vectorized nature of NumPy arrays and functions minimizes the need for computationally expensive loops. A modular Python code base has been developed to compute BTCs using embedded analytical solutions at pumping wells based on an existing well-documented finite-difference groundwater-flow simulation code (MODFLOW) and a semi-analytical particle-tracking code (MODPATH). The Python code base is tested by comparing BTCs with highly discretized synthetic steady
Comparative aseismic response study of different analytical models of nuclear power plant
International Nuclear Information System (INIS)
Takemori, T.; Ogiwara, Y.; Kawakatsu, T.; Abe, Y.; Kitade, K.
1977-01-01
This study consists of two major sections; one is comparison of magnification factor of input acceleration between finite model and spring-mass model, the other is evaluation of modified spring-mass models for aseismic design of nuclear power plant. The structure model used in this study is a P.W.R. reactor containment building composed of the outer shield wall, the steel containment and the internal structure. The rigidity of the foundation rock is represented by shear wave velocity Vs. The magnification of bedrock acceleration at the structure foundation, main floors and free surface of foundation rock are calculated using axisymmetric finite element analytical model with various rock rigidities. The outer shield wall and the steel containment are represented by shell elements, and the internal structure and foundation rock are represented by quadrilateral elements. Each nodal point has four degrees of freedom, in shell element, and three in quadrilateral element. The total degrees of this analytical model are large, so the eigenvalue is calculated by the subspace iterative method. The responses are calculated by time history of acceleration and response spectrum based on the mode superposition method. The spring-mass model is most used in aseismic design for its simplicity. But, if the foundation rock spring is calculated assuming the semi-infinite elastic solid, the analyses of the magnification of acceleration in foundation rock are limited. From the calculated results of the F.E.M. model, the modification of the spring-mass model is estimated, considering the magnification ratio of foundation rock beneath the structure
Ng, Kenney; Ghoting, Amol; Steinhubl, Steven R; Stewart, Walter F; Malin, Bradley; Sun, Jimeng
2014-04-01
Healthcare analytics research increasingly involves the construction of predictive models for disease targets across varying patient cohorts using electronic health records (EHRs). To facilitate this process, it is critical to support a pipeline of tasks: (1) cohort construction, (2) feature construction, (3) cross-validation, (4) feature selection, and (5) classification. To develop an appropriate model, it is necessary to compare and refine models derived from a diversity of cohorts, patient-specific features, and statistical frameworks. The goal of this work is to develop and evaluate a predictive modeling platform that can be used to simplify and expedite this process for health data. To support this goal, we developed a PARAllel predictive MOdeling (PARAMO) platform which (1) constructs a dependency graph of tasks from specifications of predictive modeling pipelines, (2) schedules the tasks in a topological ordering of the graph, and (3) executes those tasks in parallel. We implemented this platform using Map-Reduce to enable independent tasks to run in parallel in a cluster computing environment. Different task scheduling preferences are also supported. We assess the performance of PARAMO on various workloads using three datasets derived from the EHR systems in place at Geisinger Health System and Vanderbilt University Medical Center and an anonymous longitudinal claims database. We demonstrate significant gains in computational efficiency against a standard approach. In particular, PARAMO can build 800 different models on a 300,000 patient data set in 3h in parallel compared to 9days if running sequentially. This work demonstrates that an efficient parallel predictive modeling platform can be developed for EHR data. This platform can facilitate large-scale modeling endeavors and speed-up the research workflow and reuse of health information. This platform is only a first step and provides the foundation for our ultimate goal of building analytic pipelines
Directory of Open Access Journals (Sweden)
Kristen J Margevicius
Full Text Available Epidemiological modeling for infectious disease is important for disease management and its routine implementation needs to be facilitated through better description of models in an operational context. A standardized model characterization process that allows selection or making manual comparisons of available models and their results is currently lacking. A key need is a universal framework to facilitate model description and understanding of its features. Los Alamos National Laboratory (LANL has developed a comprehensive framework that can be used to characterize an infectious disease model in an operational context. The framework was developed through a consensus among a panel of subject matter experts. In this paper, we describe the framework, its application to model characterization, and the development of the Biosurveillance Analytics Resource Directory (BARD; http://brd.bsvgateway.org/brd/, to facilitate the rapid selection of operational models for specific infectious/communicable diseases. We offer this framework and associated database to stakeholders of the infectious disease modeling field as a tool for standardizing model description and facilitating the use of epidemiological models.
Margevicius, Kristen J; Generous, Nicholas; Abeyta, Esteban; Althouse, Ben; Burkom, Howard; Castro, Lauren; Daughton, Ashlynn; Del Valle, Sara Y; Fairchild, Geoffrey; Hyman, James M; Kiang, Richard; Morse, Andrew P; Pancerella, Carmen M; Pullum, Laura; Ramanathan, Arvind; Schlegelmilch, Jeffrey; Scott, Aaron; Taylor-McCabe, Kirsten J; Vespignani, Alessandro; Deshpande, Alina
2016-01-01
Epidemiological modeling for infectious disease is important for disease management and its routine implementation needs to be facilitated through better description of models in an operational context. A standardized model characterization process that allows selection or making manual comparisons of available models and their results is currently lacking. A key need is a universal framework to facilitate model description and understanding of its features. Los Alamos National Laboratory (LANL) has developed a comprehensive framework that can be used to characterize an infectious disease model in an operational context. The framework was developed through a consensus among a panel of subject matter experts. In this paper, we describe the framework, its application to model characterization, and the development of the Biosurveillance Analytics Resource Directory (BARD; http://brd.bsvgateway.org/brd/), to facilitate the rapid selection of operational models for specific infectious/communicable diseases. We offer this framework and associated database to stakeholders of the infectious disease modeling field as a tool for standardizing model description and facilitating the use of epidemiological models.
Short-Term Forecasting Models for Photovoltaic Plants: Analytical versus Soft-Computing Techniques
Directory of Open Access Journals (Sweden)
Claudio Monteiro
2013-01-01
Full Text Available We present and compare two short-term statistical forecasting models for hourly average electric power production forecasts of photovoltaic (PV plants: the analytical PV power forecasting model (APVF and the multiplayer perceptron PV forecasting model (MPVF. Both models use forecasts from numerical weather prediction (NWP tools at the location of the PV plant as well as the past recorded values of PV hourly electric power production. The APVF model consists of an original modeling for adjusting irradiation data of clear sky by an irradiation attenuation index, combined with a PV power production attenuation index. The MPVF model consists of an artificial neural network based model (selected among a large set of ANN optimized with genetic algorithms, GAs. The two models use forecasts from the same NWP tool as inputs. The APVF and MPVF models have been applied to a real-life case study of a grid-connected PV plant using the same data. Despite the fact that both models are quite different, they achieve very similar results, with forecast horizons covering all the daylight hours of the following day, which give a good perspective of their applicability for PV electric production sale bids to electricity markets.
A three-dimensional (3D) analytical model for subthreshold characteristics of uniformly doped FinFET
Tripathi, Shweta; Narendar, Vadthiya
2015-07-01
In this paper, three dimensional (3D) analytical model for subthreshold characteristics of doped FinFET has been presented. The separation of variables technique is used to solve the 3D Poisson's equation analytically with appropriate boundary conditions so as to obtain the expression for channel potential. The thus obtained potential distribution function has been employed in deriving subthreshold current and subthreshold slope model. The channel potential characteristics have been studied as a function of various device parameters such as gate length, gate oxide thickness and channel doping. The proposed analytical model results have been validated by comparing with the simulation data obtained by the 3D device simulator ATLAS™ from Silvaco.
Lin, M.; Katul, G. G.; Khlystov, A.
2012-05-01
The removal of ultrafine particles (UFP) by vegetation is now receiving significant attention given their role in cloud physics, human health and respiratory related diseases. Vegetation is known to be a sink for UFP, prompting interest in their collection efficiency. A number of models have tackled the UFP collection efficiency of an isolated leaf or a flat surface; however, up-scaling these theories to the ecosystem level has resisted complete theoretical treatment. To progress on a narrower scope of this problem, simultaneous experimental and theoretical investigations are carried out at the “intermediate” branch scale. Such a scale retains the large number of leaves and their interaction with the flow without the heterogeneities and added geometric complexities encountered within ecosystems. The experiments focused on the collection efficiencies of UFP in the size range 12.6-102 nm for pine and juniper branches in a wind tunnel facility. Scanning mobility particle sizers were used to measure the concentration of each diameter class of UFP upstream and downstream of the vegetation branches thereby allowing the determination of the UFP vegetation collection efficiencies. The UFP vegetation collection efficiency was measured at different wind speeds (0.3-1.5 m s-1), packing density (i.e. volume fraction of leaf or needle fibers; 0.017 and 0.040 for pine and 0.037, 0.055 for juniper), and branch orientations. These measurements were then used to investigate the performance of a proposed analytical model that predicts the branch-scale collection efficiency using conventional canopy properties such as the drag coefficient and leaf area density. Despite the numerous simplifications employed, the proposed analytical model agreed with the wind tunnel measurements mostly to within 20%. This analytical tractability can benefit future air quality and climate models incorporating UFP.
An analytic treatment for a model of superclustering in the universe
Energy Technology Data Exchange (ETDEWEB)
Kulsrud, R.M.; Cowley, S.C.
1989-01-01
Recently, Weinberg, Ostriker, and Dekel (WOD) have proposed a model of many spherical explosions which reproduces the large scale structure of the universe quite well. Because of the success of the model, we have developed an analytic treatment which gives the cluster-cluster correlation function and the cluster mass distribution in terms of the distribution of radii of the spherical voids. We also derive an expression for the distribution in terms of the cluster mass distribution. Thus, the cluster-cluster correlation function is given in terms of the cluster mass distribution function. The numerical results of WOD agree quite well with the predictions from the observed mass distribution. We give the cluster-cluster correlation function for several model distributions of radii. This formulation should be useful for future comparisons of observation and the model of WOD. 4 refs., 5 figs.
Chiadamrong, N.; Piyathanavong, V.
2017-12-01
Models that aim to optimize the design of supply chain networks have gained more interest in the supply chain literature. Mixed-integer linear programming and discrete-event simulation are widely used for such an optimization problem. We present a hybrid approach to support decisions for supply chain network design using a combination of analytical and discrete-event simulation models. The proposed approach is based on iterative procedures until the difference between subsequent solutions satisfies the pre-determined termination criteria. The effectiveness of proposed approach is illustrated by an example, which shows closer to optimal results with much faster solving time than the results obtained from the conventional simulation-based optimization model. The efficacy of this proposed hybrid approach is promising and can be applied as a powerful tool in designing a real supply chain network. It also provides the possibility to model and solve more realistic problems, which incorporate dynamism and uncertainty.
International Nuclear Information System (INIS)
Frankle, S.C.; Fitzgerald, D.H.; Hutson, R.L.; Macek, R.J.; Wilkinson, C.A.
1993-01-01
Neutron dose equivalent rates have been measured for 800-MeV proton beam spills at the Los Alamos Meson Physics Facility. Neutron detectors were used to measure the neutron dose levels at a number of locations for each beam-spill test, and neutron energy spectra were measured for several beam-spill tests. Estimates of expected levels for various detector locations were made using a simple analytical model developed for 800-MeV proton beam spills. A comparison of measurements and model estimates indicates that the model is reasonably accurate in estimating the neutron dose equivalent rate for simple shielding geometries. The model fails for more complicated shielding geometries, where indirect contributions to the dose equivalent rate can dominate
Data collapse, scaling functions, and analytical solutions of generalized growth models.
Cabella, Brenno Caetano Troca; Martinez, Alexandre Souto; Ribeiro, Fabiano
2011-06-01
We consider a nontrivial one-species population dynamics model with finite and infinite carrying capacities. Time-dependent intrinsic and extrinsic growth rates are considered in these models. Through the model per capita growth rate we obtain a heuristic general procedure to generate scaling functions to collapse data into a simple linear behavior even if an extrinsic growth rate is included. With this data collapse, all the models studied become independent from the parameters and initial condition. Analytical solutions are found when time-dependent coefficients are considered. These solutions allow us to perceive nontrivial transitions between species extinction and survival and to calculate the transition's critical exponents. Considering an extrinsic growth rate as a cancer treatment, we show that the relevant quantity depends not only on the intensity of the treatment, but also on when the cancerous cell growth is maximum.
A two-dimensional analytical model of laminar flame in lycopodium dust particles
Energy Technology Data Exchange (ETDEWEB)
Rahbari, Alireza [Shahid Rajaee Teacher Training University, Tehran (Iran, Islamic Republic of); Shakibi, Ashkan [Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Bidabadi, Mehdi [Combustion Research Laboratory, Narmak, Tehran (Iran, Islamic Republic of)
2015-09-15
A two-dimensional analytical model is presented to determine the flame speed and temperature distribution of micro-sized lycopodium dust particles. This model is based on the assumptions that the particle burning rate in the flame front is controlled by the process of oxygen diffusion and the flame structure consists of preheat, reaction and post flame zones. In the first step, the energy conservation equations for fuel-lean condition are expressed in two dimensions, and then these differential equations are solved using the required boundary condition and matching the temperature and heat flux at the interfacial boundaries. Consequently, the obtained flame temperature and flame speed distributions in terms of different particle diameters and equivalence ratio for lean mixture are compared with the corresponding experimental data for lycopodium dust particles. Consequently, it is shown that this two-dimensional model demonstrates better agreement with the experimental results compared to the previous models.
Analytical model for three-dimensional Mercedes-Benz water molecules
Urbic, T.
2013-01-01
We developed a statistical model which describes the thermal and volumetric properties of water-like molecules. A molecule is presented as a three-dimensional sphere with four hydrogen-bonding arms. Each water molecule interacts with its neighboring waters through a van der Waals interaction and an orientation-dependent hydrogen-bonding interaction. This model, which is largely analytical, is a variant of a model developed before for a two-dimensional Mercedes-Benz model of water. We explored properties such as molar volume, density, heat capacity, thermal expansion coefficient, and isothermal compressibility as a function of temperature and pressure. We found that the volumetric and thermal properties follow the same trends with temperature as in real water and are in good general agreement with Monte Carlo simulations, including the density anomaly, the minimum in the isothermal compressibility, and the decreased number of hydrogen bonds upon increasing the temperature. PMID:23005100
Analytical model for three-dimensional Mercedes-Benz water molecules.
Urbic, T
2012-06-01
We developed a statistical model which describes the thermal and volumetric properties of water-like molecules. A molecule is presented as a three-dimensional sphere with four hydrogen-bonding arms. Each water molecule interacts with its neighboring waters through a van der Waals interaction and an orientation-dependent hydrogen-bonding interaction. This model, which is largely analytical, is a variant of a model developed before for a two-dimensional Mercedes-Benz model of water. We explored properties such as molar volume, density, heat capacity, thermal expansion coefficient, and isothermal compressibility as a function of temperature and pressure. We found that the volumetric and thermal properties follow the same trends with temperature as in real water and are in good general agreement with Monte Carlo simulations, including the density anomaly, the minimum in the isothermal compressibility, and the decreased number of hydrogen bonds upon increasing the temperature.
Self-consistent semi-analytic models of the first stars
Visbal, Eli; Haiman, Zoltán; Bryan, Greg L.
2018-01-01
We have developed a semi-analytic framework to model the large-scale evolution of the first Population III (Pop III) stars and the transition to metal-enriched star formation. Our model follows dark matter halos from cosmological N-body simulations, utilizing their individual merger histories and three-dimensional positions, and applies physically motivated prescriptions for star formation and feedback from Lyman-Werner (LW) radiation, hydrogen ionizing radiation, and external metal enrichment due to supernovae winds. This method is intended to complement analytic studies, which do not include clustering or individual merger histories, and hydrodynamical cosmological simulations, which include detailed physics, but are computationally expensive and have limited dynamic range. Utilizing this technique, we compute the cumulative Pop III and metal-enriched star formation rate density (SFRD) as a function of redshift at z ≥ 20. We find that varying the model parameters leads to significant qualitative changes in the global star formation history. The Pop III star formation efficiency and the delay time between Pop III and subsequent metal-enriched star formation are found to have the largest impact. The effect of clustering (i.e. including the three-dimensional positions of individual halos) on various feedback mechanisms is also investigated. The impact of clustering on LW and ionization feedback is found to be relatively mild in our fiducial model, but can be larger if external metal enrichment can promote metal-enriched star formation over large distances.
International Nuclear Information System (INIS)
Hua Ting-Ting; Guo Yu-Feng; Yu Ying; Jian Tong; Yao Jia-Fei; Sheu Gene
2013-01-01
By solving the 2D Poisson's equation, analytical models are proposed to calculate the surface potential and electric field distributions of lateral power devices with arbitrary vertical doping profiles. The vertical and the lateral breakdown voltages are formulized to quantify the breakdown characteristic in completely-depleted and partially-depleted cases. A new reduced surface field (RESURF) criterion which can be used in various drift doping profiles is further derived for obtaining the optimal trade-off between the breakdown voltage and the on-resistance. Based on these models and the numerical simulation, the electric field modulation mechanism and the breakdown characteristics of lateral power devices are investigated in detail for the uniform, linear, Gaussian, and some discrete doping profiles along the vertical direction in the drift region. Then, the mentioned vertical doping profiles of these devices with the same geometric parameters are optimized, and the results show that the optimal breakdown voltages and the effective drift doping concentrations of these devices are identical, which are equal to those of the uniform-doped device, respectively. The analytical results of these proposed models are in good agreement with the numerical results and the previous experimental results, confirming the validity of the models presented here. (interdisciplinary physics and related areas of science and technology)
Analytical modelling of resistive wall mode stabilization by rotation in toroidal tokamak plasmas
International Nuclear Information System (INIS)
Ham, C J; Gimblett, C G; Hastie, R J
2011-01-01
Stabilization of the resitive wall mode (RWM) may allow fusion power to be doubled for a given magnetic field in advanced tokamak operation. Experimental evidence from DIII-D and other machines suggests that plasma rotation can stabilize the RWM. Several authors (Finn 1995 Phys. Plasmas 2 3782, Bondeson and Xie 1997 Phys. Plasmas 4 2081) have constructed analytical cylindrical models for the RWM, but these do not deal with toroidal effects. The framework of Connor et al (1988 Phys. Fluids 31 577) is used to develop ideal plasma analytic models with toroidicity included. Stepped pressure profiles and careful ordering of terms are used to simplify the analysis. First, a current driven kink mode model is developed and a dispersion relation for arbitrary current profile is calculated. Second, the external pressure driven kink mode is similarly investigated as the most important RWM arises from this mode. Using this latter model it is found that the RWM is stabilized by Alfven continuum damping with rotation levels similar to those seen in experiments. An expression for the stability of the external kink mode for more general current profiles and a resistive wall is derived in the appendix.
CALIBRATION OF SEMI-ANALYTIC MODELS OF GALAXY FORMATION USING PARTICLE SWARM OPTIMIZATION
International Nuclear Information System (INIS)
Ruiz, Andrés N.; Domínguez, Mariano J.; Yaryura, Yamila; Lambas, Diego García; Cora, Sofía A.; Martínez, Cristian A. Vega-; Gargiulo, Ignacio D.; Padilla, Nelson D.; Tecce, Tomás E.; Orsi, Álvaro; Arancibia, Alejandra M. Muñoz
2015-01-01
We present a fast and accurate method to select an optimal set of parameters in semi-analytic models of galaxy formation and evolution (SAMs). Our approach compares the results of a model against a set of observables applying a stochastic technique called Particle Swarm Optimization (PSO), a self-learning algorithm for localizing regions of maximum likelihood in multidimensional spaces that outperforms traditional sampling methods in terms of computational cost. We apply the PSO technique to the SAG semi-analytic model combined with merger trees extracted from a standard Lambda Cold Dark Matter N-body simulation. The calibration is performed using a combination of observed galaxy properties as constraints, including the local stellar mass function and the black hole to bulge mass relation. We test the ability of the PSO algorithm to find the best set of free parameters of the model by comparing the results with those obtained using a MCMC exploration. Both methods find the same maximum likelihood region, however, the PSO method requires one order of magnitude fewer evaluations. This new approach allows a fast estimation of the best-fitting parameter set in multidimensional spaces, providing a practical tool to test the consequences of including other astrophysical processes in SAMs
Self-consistent semi-analytic models of the first stars
Visbal, Eli; Haiman, Zoltán; Bryan, Greg L.
2018-04-01
We have developed a semi-analytic framework to model the large-scale evolution of the first Population III (Pop III) stars and the transition to metal-enriched star formation. Our model follows dark matter haloes from cosmological N-body simulations, utilizing their individual merger histories and three-dimensional positions, and applies physically motivated prescriptions for star formation and feedback from Lyman-Werner (LW) radiation, hydrogen ionizing radiation, and external metal enrichment due to supernovae winds. This method is intended to complement analytic studies, which do not include clustering or individual merger histories, and hydrodynamical cosmological simulations, which include detailed physics, but are computationally expensive and have limited dynamic range. Utilizing this technique, we compute the cumulative Pop III and metal-enriched star formation rate density (SFRD) as a function of redshift at z ≥ 20. We find that varying the model parameters leads to significant qualitative changes in the global star formation history. The Pop III star formation efficiency and the delay time between Pop III and subsequent metal-enriched star formation are found to have the largest impact. The effect of clustering (i.e. including the three-dimensional positions of individual haloes) on various feedback mechanisms is also investigated. The impact of clustering on LW and ionization feedback is found to be relatively mild in our fiducial model, but can be larger if external metal enrichment can promote metal-enriched star formation over large distances.
International Nuclear Information System (INIS)
Massoud, M.
1987-01-01
Natural Circulation phenomena in a simulated PWR was investigated experimentally and analytically. The experimental investigation included determination of system characteristics as well as system response to the imposed transient under symmetric and asymmetric operations. System characteristics were used to obtain correlation for heat transfer coefficient in heat exchangers, system flow resistance, and system buoyancy heat. Asymmetric transients were imposed to study flow oscillation and possible instability. The analytical investigation encompassed development of mathematical model for single-phase, steady-state and transient natural circulation as well as modification of existing model for two-phase flow analysis of phenomena such as small break LOCA, high pressure coolant injection and pump coast down. The developed mathematical model for single-phase analysis was computer coded to simulate the imposed transients. The computer program, entitled ''Symmetric and Asymmetric Analysis of Single-Phase Flow (SAS),'' were employed to simulate the imposed transients. It closely emulated the system behavior throughout the transient and subsequent steady-state. Modifications for two-phase flow analysis included addition of models for once-through steam generator and electric heater rods. Both programs are faster than real time. Off-line, they can be used for prediction and training applications while on-line they serve for simulation and signal validation. The programs can also be used to determine the sensitivity of natural circulation behavior to variation of inputs such as secondary distribution and power transients
Franesqui, Miguel A; Yepes, Jorge; García-González, Cándida
2017-08-01
This article outlines the ultrasound data employed to calibrate in the laboratory an analytical model that permits the calculation of the depth of partial-depth surface-initiated cracks on bituminous pavements using this non-destructive technique. This initial calibration is required so that the model provides sufficient precision during practical application. The ultrasonic pulse transit times were measured on beam samples of different asphalt mixtures (semi-dense asphalt concrete AC-S; asphalt concrete for very thin layers BBTM; and porous asphalt PA). The cracks on the laboratory samples were simulated by means of notches of variable depths. With the data of ultrasound transmission time ratios, curve-fittings were carried out on the analytical model, thus determining the regression parameters and their statistical dispersion. The calibrated models obtained from laboratory datasets were subsequently applied to auscultate the evolution of the crack depth after microwaves exposure in the research article entitled "Top-down cracking self-healing of asphalt pavements with steel filler from industrial waste applying microwaves" (Franesqui et al., 2017) [1].
Directory of Open Access Journals (Sweden)
Miguel A. Franesqui
2017-08-01
Full Text Available This article outlines the ultrasound data employed to calibrate in the laboratory an analytical model that permits the calculation of the depth of partial-depth surface-initiated cracks on bituminous pavements using this non-destructive technique. This initial calibration is required so that the model provides sufficient precision during practical application. The ultrasonic pulse transit times were measured on beam samples of different asphalt mixtures (semi-dense asphalt concrete AC-S; asphalt concrete for very thin layers BBTM; and porous asphalt PA. The cracks on the laboratory samples were simulated by means of notches of variable depths. With the data of ultrasound transmission time ratios, curve-fittings were carried out on the analytical model, thus determining the regression parameters and their statistical dispersion. The calibrated models obtained from laboratory datasets were subsequently applied to auscultate the evolution of the crack depth after microwaves exposure in the research article entitled “Top-down cracking self-healing of asphalt pavements with steel filler from industrial waste applying microwaves” (Franesqui et al., 2017 [1].
Xie, Dexuan; Volkmer, Hans W.; Ying, Jinyong
2016-04-01
The nonlocal dielectric approach has led to new models and solvers for predicting electrostatics of proteins (or other biomolecules), but how to validate and compare them remains a challenge. To promote such a study, in this paper, two typical nonlocal dielectric models are revisited. Their analytical solutions are then found in the expressions of simple series for a dielectric sphere containing any number of point charges. As a special case, the analytical solution of the corresponding Poisson dielectric model is also derived in simple series, which significantly improves the well known Kirkwood's double series expansion. Furthermore, a convolution of one nonlocal dielectric solution with a commonly used nonlocal kernel function is obtained, along with the reaction parts of these local and nonlocal solutions. To turn these new series solutions into a valuable research tool, they are programed as a free fortran software package, which can input point charge data directly from a protein data bank file. Consequently, different validation tests can be quickly done on different proteins. Finally, a test example for a protein with 488 atomic charges is reported to demonstrate the differences between the local and nonlocal models as well as the importance of using the reaction parts to develop local and nonlocal dielectric solvers.
Energy Technology Data Exchange (ETDEWEB)
Massoud, M
1987-01-01
Natural Circulation phenomena in a simulated PWR was investigated experimentally and analytically. The experimental investigation included determination of system characteristics as well as system response to the imposed transient under symmetric and asymmetric operations. System characteristics were used to obtain correlation for heat transfer coefficient in heat exchangers, system flow resistance, and system buoyancy heat. Asymmetric transients were imposed to study flow oscillation and possible instability. The analytical investigation encompassed development of mathematical model for single-phase, steady-state and transient natural circulation as well as modification of existing model for two-phase flow analysis of phenomena such as small break LOCA, high pressure coolant injection and pump coast down. The developed mathematical model for single-phase analysis was computer coded to simulate the imposed transients. The computer program, entitled ''Symmetric and Asymmetric Analysis of Single-Phase Flow (SAS),'' were employed to simulate the imposed transients. It closely emulated the system behavior throughout the transient and subsequent steady-state. Modifications for two-phase flow analysis included addition of models for once-through steam generator and electric heater rods. Both programs are faster than real time. Off-line, they can be used for prediction and training applications while on-line they serve for simulation and signal validation. The programs can also be used to determine the sensitivity of natural circulation behavior to variation of inputs such as secondary distribution and power transients.
Computational Assessment of Neural Probe and Brain Tissue Interface under Transient Motion
Directory of Open Access Journals (Sweden)
Michael Polanco
2016-06-01
Full Text Available The functional longevity of a neural probe is dependent upon its ability to minimize injury risk during the insertion and recording period in vivo, which could be related to motion-related strain between the probe and surrounding tissue. A series of finite element analyses was conducted to study the extent of the strain induced within the brain in an area around a neural probe. This study focuses on the transient behavior of neural probe and brain tissue interface with a viscoelastic model. Different stages of the interface from initial insertion of neural probe to full bonding of the probe by astro-glial sheath formation are simulated utilizing analytical tools to investigate the effects of relative motion between the neural probe and the brain while friction coefficients and kinematic frequencies are varied. The analyses can provide an in-depth look at the quantitative benefits behind using soft materials for neural probes.
Cortese, Samuele; Castellanos, F Xavier; Eickhoff, Claudia R; D'Acunto, Giulia; Masi, Gabriele; Fox, Peter T; Laird, Angela R; Eickhoff, Simon B
2016-12-15
Task-based functional magnetic resonance imaging (fMRI) studies of adult attention-deficit/hyperactivity disorder (ADHD) have revealed various ADHD-related dysfunctional brain regions, with heterogeneous findings across studies. Here, we used novel meta-analytic data-driven approaches to characterize the function and connectivity profile of ADHD-related dysfunctional regions consistently detected across studies. We first conducted an activation likelihood estimation meta-analysis of 24 task-based fMRI studies in adults with ADHD. Each ADHD-related dysfunctional region resulting from the activation likelihood estimation meta-analysis was then analyzed using functional decoding based on ~7500 fMRI experiments in the BrainMap database. This approach allows mapping brain regions to functions not necessarily tested in individual studies, thus suggesting possible novel functions for those regions. Additionally, ADHD-related dysfunctional regions were clustered based on their functional coactivation profiles across all the experiments stored in BrainMap (meta-analytic connectivity modeling). ADHD-related hypoactivation was found in the left putamen, left inferior frontal gyrus (pars opercularis), left temporal pole, and right caudate. Functional decoding mapped the left putamen to cognitive aspects of music perception/reproduction and the left temporal lobe to language semantics; both these regions clustered together on the basis of their meta-analytic functional connectivity. Left inferior gyrus mapped to executive function tasks; right caudate mapped to both executive function tasks and music-related processes. Our study provides meta-analytic support to the hypothesis that, in addition to well-known deficits in typical executive functions, impairment in processes related to music perception/reproduction and language semantics may be involved in the pathophysiology of adult ADHD. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights
Analytic properties of the quark propagator from an effective infrared interaction model
Windisch, Andreas
2017-04-01
In this paper, I investigate the analytic properties of the quark propagator Dyson-Schwinger equation (DSE) in the Landau gauge. In the quark self-energy, the combined gluon propagator and quark-gluon vertex is modeled by an effective interaction (the so-called Maris-Tandy interaction), where the ultraviolet term is neglected. This renders the loop integrand of the quark self-energy analytic on the cut plane -π complex conjugation symmetry, this region fully covers the parabolic integration domain for Bethe-Salpeter equations (BSEs) for bound state masses of up to 4.5 GeV. Employing a novel numerical technique that is based on highly parallel computation on graphics processing units (GPUs), I extract more than 6500 poles in this region, which arise as the bare quark mass is varied over a wide range of closely spaced values. The poles are grouped in 23 individual trajectories that capture the movement of the poles in the complex region as the bare mass is varied. The raw data of the pole locations and residues is provided as Supplemental Material, which can be used to parametrize solutions of the complex quark propagator for a wide range of bare mass values and for large bound-state masses. This study is a first step towards an extension of previous work on the analytic continuation of perturbative one-loop integrals, with the long-term goal of establishing a framework that allows for the numerical extraction of the analytic properties of the quark propagator with a truncation that extends beyond the rainbow by making adequate adjustments in the contour of the radial integration of the quark self-energy.
An Analytical Model for Multilayer Well Production Evaluation to Overcome Cross-Flow Problem
Hakiki, Farizal
2017-10-17
One of the major concerns in a multi-layer system is that interlayer cross-flow may occur if reservoir fluids are produced from commingled layers that have unequal initial pressures. Reservoir would commonly have bigger average reservoir pressure (pore fluid pressure) as it goes deeper. The phenomenon is, however, not followed by the reservoir productivity or injectivity. The existence of reservoir with quite low average-pressure and high injectivity would tend experiencing the cross-flow problem. It is a phenomenon of fluid from bottom layer flowing into upper layer. It would strict upper-layer fluid to flow into wellbore. It is as if there is an injection treatment from bottom layer. The study deploys productivity index an approach parameter taking into account of cross-flow problem instead of injectivity index since it is a production well. The analytical study is to model the reservoir multilayer by addressing to avoid cross-flow problem. The analytical model employed hypothetical and real field data to test it. The scope of this study are: (a) Develop mathematical-based solution to determine the production rate from each layer; (b) Assess different scenarios to optimize production rate, those are: pump setting depth and performance of in-situ choke (ISC) installation. The ISC is acting as an inflow control device (ICD) alike that help to reduce cross-flow occurrence. This study employed macro program to write the code and develop the interface. Fast iterative procedure happens on solving the analytical model. Comparison results recognized that the mathematical-based solution shows a good agreement with the commercial software derived results.
Analytical models for coupling reliability in identical two-magnet systems during slow reversals
Kani, Nickvash; Naeemi, Azad
2017-12-01
This paper follows previous works which investigated the strength of dipolar coupling in two-magnet systems. While those works focused on qualitative analyses, this manuscript elucidates reversal through dipolar coupling culminating in analytical expressions for reversal reliability in identical two-magnet systems. The dipolar field generated by a mono-domain magnetic body can be represented by a tensor containing both longitudinal and perpendicular field components; this field changes orientation and magnitude based on the magnetization of neighboring nanomagnets. While the dipolar field does reduce to its longitudinal component at short time-scales, for slow magnetization reversals, the simple longitudinal field representation greatly underestimates the scope of parameters that ensure reliable coupling. For the first time, analytical models that map the geometric and material parameters required for reliable coupling in two-magnet systems are developed. It is shown that in biaxial nanomagnets, the x ̂ and y ̂ components of the dipolar field contribute to the coupling, while all three dimensions contribute to the coupling between a pair of uniaxial magnets. Additionally, the ratio of the longitudinal and perpendicular components of the dipolar field is also very important. If the perpendicular components in the dipolar tensor are too large, the nanomagnet pair may come to rest in an undesirable meta-stable state away from the free axis. The analytical models formulated in this manuscript map the minimum and maximum parameters for reliable coupling. Using these models, it is shown that there is a very small range of material parameters which can facilitate reliable coupling between perpendicular-magnetic-anisotropy nanomagnets; hence, in-plane nanomagnets are more suitable for coupled systems.
Stand dynamics and tree coexistence in an analytical structured model: the role of recruitment.
Angulo, Óscar; Bravo de la Parra, Rafael; López-Marcos, Juan C; Zavala, Miguel A
2013-09-21
Understanding the mechanisms of coexistence and niche partitioning in plant communities is a central question in ecology. Current theories of forest dynamics range between the so-called neutral theories which assume functional equivalence among coexisting species to forest simulators that explain species assemblages as the result of tradeoffs in species individual strategies at several ontogenetic stages. Progress in these questions has been hindered by the inherent difficulties of developing analytical size-structured models of stand dynamics. This precludes examination of the relative importance of each mechanism on tree coexistence. In previous simulation and analytical studies emphasis has been given to interspecific differences at the sapling stage, and less so to interspecific variation in seedling recruitment. In this study we develop a partial differential equation model of stand dynamics in which competition takes place at the recruitment stage. Species differ in their size-dependent growth rates and constant mortality rates. Recruitment is described as proportional to the basal area of conspecifics, to account for fecundity and seed supply per unit of basal area, and is corrected with a decreasing function of species specific basal area to account for competition. We first analyze conditions for population persistence in monospecific stands and second we investigate conditions of coexistence for two species. In the monospecific case we found a stationary stand structure based on an inequality between mortality rate and seed supply. In turn, intra-specific competition does not play any role on the asymptotic extinction or population persistence. In the two-species case we found that coexistence can be attained when the reciprocal negative effect on recruitment follows a given relation with respect to intraspecific competition. Specifically a tradeoff between recruitment potential (i.e. shade tolerance or predation avoidance) and fecundity or growth rate
Avdievich, N I; Pfrommer, A; Giapitzakis, I A; Henning, A
2017-10-01
Ultrahigh-field (UHF) (≥7 T) transmit (Tx) human head surface loop phased arrays improve both the Tx efficiency (B 1 + /√P) and homogeneity in comparison with single-channel quadrature Tx volume coils. For multi-channel arrays, decoupling becomes one of the major problems during the design process. Further insight into the coupling between array elements and its dependence on various factors can facilitate array development. The evaluation of the entire impedance matrix Z for an array loaded with a realistic voxel model or phantom is a time-consuming procedure when performed using electromagnetic (EM) solvers. This motivates the development of an analytical model, which could provide a quick assessment of the Z-matrix. In this work, an analytical model based on dyadic Green's functions was developed and validated using an EM solver and bench measurements. The model evaluates the complex coupling, including both the electric (mutual resistance) and magnetic (mutual inductance) coupling. Validation demonstrated that the model does well to describe the coupling at lower fields (≤3 T). At UHFs, the model also performs well for a practical case of low magnetic coupling. Based on the modeling, the geometry of a 400-MHz, two-loop transceiver array was optimized, such that, by simply overlapping the loops, both the mutual inductance and the mutual resistance were compensated at the same time. As a result, excellent decoupling (below -40 dB) was obtained without any additional decoupling circuits. An overlapped array prototype was compared (signal-to-noise ratio, Tx efficiency) favorably to a gapped array, a geometry which has been utilized previously in designs of UHF Tx arrays. Copyright © 2017 John Wiley & Sons, Ltd.
Extension of semi-analytical Erbium-doped fiber amplifier model to self-saturation regime
DEFF Research Database (Denmark)
Nissov, Morten
1997-01-01
demonstrate very good agreement between measurements and simulations based on measured fiber data for both high-gain EDFAs (small-signal gain of 35 dB) and isolator EDFAs (small-signal gain of 43 dB) with deviations Academic Press.......We show in this paper that the analytical erbium-doped fiber amplifier (EDFA) model presented by Jopson and Saleh in 1991 can be extended to the self-saturation regime, making it capable of simulating all practical EDFAs. We show that an Intel Pentium 66 based computer can calculate gain and noise...
Analytical modeling of leak induced sound wave in a power plant boiler room
International Nuclear Information System (INIS)
Badsar, A.; Khosravi, F.
2005-01-01
An exact analysis for Sound propagation by a leak situated in a power plant boiler room is outlined. The Light hill model for description of free jet behavior along with the appropriate wave field expansions, the Neumann boundary conditions for boiler walls, and the classical theory of images are employed to develop a closed-form solution in form of infinite series. The analytical results are illustrated with numerical examples in which a leak in the boiler room produces spherical sound waves. The acoustic field pressure distribution is evaluated and discussed for representative values of the parameters characterizing the system. Limiting cases involving symmetric conditions of the problem are considered
Latham, T. S.; Rodgers, R. J.
1972-01-01
Analytical studies were continued to identify the design and performance characteristics of a small-scale model of a nuclear light bulb unit cell suitable for testing in a nuclear furnace reactor. Emphasis was placed on calculating performance characteristics based on detailed radiant heat transfer analyses, on designing the test assembly for ease of insertion, connection, and withdrawal at the reactor test cell, and on determining instrumentation and test effluent handling requirements. In addition, a review of candidate test reactors for future nuclear light bulb in-reactor tests was conducted.
Energy Technology Data Exchange (ETDEWEB)
Zou, Li [Dalian Univ. of Technology, Dalian City (China). State Key Lab. of Structural Analysis for Industrial Equipment; Liang, Songxin; Li, Yawei [Dalian Univ. of Technology, Dalian City (China). School of Mathematical Sciences; Jeffrey, David J. [Univ. of Western Ontario, London (Canada). Dept. of Applied Mathematics
2017-06-01
Nonlinear boundary value problems arise frequently in physical and mechanical sciences. An effective analytic approach with two parameters is first proposed for solving nonlinear boundary value problems. It is demonstrated that solutions given by the two-parameter method are more accurate than solutions given by the Adomian decomposition method (ADM). It is further demonstrated that solutions given by the ADM can also be recovered from the solutions given by the two-parameter method. The effectiveness of this method is demonstrated by solving some nonlinear boundary value problems modeling beam-type nano-electromechanical systems.