Theoretical models for supernovae
Woosley, S.E.; Weaver, T.A.
1981-09-21
The results of recent numerical simulations of supernova explosions are presented and a variety of topics discussed. Particular emphasis is given to (i) the nucleosynthesis expected from intermediate mass (10sub solar less than or equal to M less than or equal to 100 Msub solar) Type II supernovae and detonating white dwarf models for Type I supernovae, (ii) a realistic estimate of the ..gamma..-line fluxes expected from this nucleosynthesis, (iii) the continued evolution, in one and two dimensions, of intermediate mass stars wherein iron core collapse does not lead to a strong, mass-ejecting shock wave, and (iv) the evolution and explosion of vary massive stars (M greater than or equal to 100 Msub solar of both Population I and III. In one dimension, nuclear burning following a failed core bounce does not appear likely to lead to a supernova explosion although, in two dimensions, a combination of rotation and nuclear burning may do so. Near solar proportions of elements from neon to calcium and very brilliant optical displays may be created by hypernovae, the explosions of stars in the mass range 100 M/sub solar/ to 300 M/sub solar/. Above approx. 300 M/sub solar/ a black hole is created by stellar collapse following carbon ignition. Still more massive stars may be copious producers of /sup 4/He and /sup 14/N prior to their collapse on the pair instability.
Social Impact, a Theoretical Model
Jenny Onyx
2014-01-01
Full Text Available This paper constructs a theoretical model of social impact as it applies to civil society organisations. It does so by drawing on the recent literature on the topic as well as recently completed empirical studies. First, the relationship between impact and evaluation is examined. This is followed by an exploration of the capitals, notably social, human, and cultural capital and their interrelationships, as a theoretical base for the explication of social impact. A formal model of social impact is then identified together with a set of basic principles that may be said to define social impact. Finally the implications of the model are discussed for social policy and organisational management.
Theoretical Models of Generalized Quasispecies.
Wagner, Nathaniel; Atsmon-Raz, Yoav; Ashkenasy, Gonen
2016-01-01
Theoretical modeling of quasispecies has progressed in several directions. In this chapter, we review the works of Emmanuel Tannenbaum, who, together with Eugene Shakhnovich at Harvard University and later with colleagues and students at Ben-Gurion University in Beersheva, implemented one of the more useful approaches, by progressively setting up various formulations for the quasispecies model and solving them analytically. Our review will focus on these papers that have explored new models, assumed the relevant mathematical approximations, and proceeded to analytically solve for the steady-state solutions and run stochastic simulations . When applicable, these models were related to real-life problems and situations, including changing environments, presence of chemical mutagens, evolution of cancer and tumor cells , mutations in Escherichia coli, stem cells , chromosomal instability (CIN), propagation of antibiotic drug resistance , dynamics of bacteria with plasmids , DNA proofreading mechanisms, and more.
Theoretical model of ``fuzz'' growth
Krasheninnikov, Sergei; Smirnov, Roman
2012-10-01
Recent more detailed experiments on tungsten irradiation with low energy helium plasma, relevant to the near-wall plasma conditions in magnetic fusion reactor like ITER, demonstrated (e.g. see Ref. 1) a very dramatic change in both surface morphology and near surface material structure of the samples. In particular, it was shown that a long (mm-scale) and thin (nm-scale) fiber-like structures filled with nano-bubbles, so-called ``fuzz,'' start to grow. In this work theoretical model of ``fuzz'' growth [2] describing the main features observed in experiments is presented. This model, based on the assumption of enhancement of creep of tungsten containing significant fraction of helium atoms and clusters. The results of the MD simulations [3] support this idea and demonstrate a strong reduction of the yield strength for all temperature range. They also show that the ``flow'' of tungsten strongly facilitates coagulation of helium clusters and the formation of nano-bubbles.[4pt] [1] M. J. Baldwin, et al., J. Nucl. Mater. 390-391 (2009) 885;[0pt] [2] S. I. Krasheninnikov, Physica Scripta T145 (2011) 014040;[0pt] [3] R. D. Smirnov and S. I. Krasheninnikov, submitted to J. Nucl. Materials.
Theoretical Models of the Galactic Bulge
Shen, Juntai; Li, Zhao-Yu
Near infrared images from the COBE satellite presented the first clear evidence that our Milky Way galaxy contains a boxy shaped bulge. Recent years have witnessed a gradual paradigm shift in the formation and evolution of the Galactic bulge. Bulges were commonly believed to form in the dynamical violence of galaxy mergers. However, it has become increasingly clear that the main body of the Milky Way bulge is not a classical bulge made by previous major mergers, instead it appears to be a bar seen somewhat end-on. The Milky Way bar can form naturally from a precursor disc and thicken vertically by the internal firehose/buckling instability, giving rise to the boxy appearance. This picture is supported by many lines of evidence, including the asymmetric parallelogram shape, the strong cylindrical rotation (i.e., nearly constant rotation regardless of the height above the disc plane), the existence of an intriguing X-shaped structure in the bulge, and perhaps the metallicity gradients. We review the major theoretical models and techniques to understand the Milky Way bulge. Despite the progresses in recent theoretical attempts, a complete bulge formation model that explains the full kinematics and metallicity distribution is still not fully understood. Upcoming large surveys are expected to shed new light on the formation history of the Galactic bulge.
A Set Theoretical Approach to Maturity Models
Lasrado, Lester; Vatrapu, Ravi; Andersen, Kim Normann
2016-01-01
Maturity Model research in IS has been criticized for the lack of theoretical grounding, methodological rigor, empirical validations, and ignorance of multiple and non-linear paths to maturity. To address these criticisms, this paper proposes a novel set-theoretical approach to maturity models ch...
Unified Hybrid Network Theoretical Model Trilogy
无
2011-01-01
The first of the unified hybrid network theoretical model trilogy (UHNTF) is the harmonious unification hybrid preferential model (HUHPM), seen in the inner loop of Fig. 1, the unified hybrid ratio is defined.
Dynamics in Higher Education Politics: A Theoretical Model
Kauko, Jaakko
2013-01-01
This article presents a model for analysing dynamics in higher education politics (DHEP). Theoretically the model draws on the conceptual history of political contingency, agenda-setting theories and previous research on higher education dynamics. According to the model, socio-historical complexity can best be analysed along two dimensions: the…
Theoretical Models for Orthogonal Cutting
De Chiffre, Leonardo
This review of simple models for orthogonal cutting was extracted from: “L. De Chiffre: Metal Cutting Mechanics and Applications, D.Sc. Thesis, Technical University of Denmark, 1990.”......This review of simple models for orthogonal cutting was extracted from: “L. De Chiffre: Metal Cutting Mechanics and Applications, D.Sc. Thesis, Technical University of Denmark, 1990.”...
Theoretical Models for Orthogonal Cutting
De Chiffre, Leonardo
This review of simple models for orthogonal cutting was extracted from: “L. De Chiffre: Metal Cutting Mechanics and Applications, D.Sc. Thesis, Technical University of Denmark, 1990.”......This review of simple models for orthogonal cutting was extracted from: “L. De Chiffre: Metal Cutting Mechanics and Applications, D.Sc. Thesis, Technical University of Denmark, 1990.”...
Theoretical model of digital archives
Alenka Kavčič-Čolić
2004-01-01
Full Text Available There are certain conditions that national organizations should fulfill to became trusted digital repositories. Among other things, their deposit system should be in compliance with the reference model for an Open Archival Information System (OAIS. In this paper the model OAIS is presented as well as some important international experiences regarding its implementation. The joint project of the National and University Library and The Jozef Stefan Institute, which is aimed at developing such a digital archive based on OAIS, is also mentioned.
Theoretical modeling of electromagnetically imploded plasma liners
Roderick, N.F.; Kohn, B.J.; McCullough, W.F.; Beason, C.W.; Lupo, J.A.; Letterio, J.D. (Air Force Weapons Lab., Kirtland AFB, NM (USA)); Kloc, D.A. (Air Force Academy, CO (USA)); Hussey, T.W. (Sandia National Labs., Albuquerque, NM (USA))
1983-05-01
The generation of high-energy-density plasmas by the electromagnetic implosion of cylindrical foils is explored analytically and through numerical simulation. Theoretical investigations have been performed for a variety of foil initial conditions for both capacitive and inductive pulsed power systems. The development of the theoretical modeling techniques is presented, covering both circuit models and plasma load models. Results from a series of configurations are given, showing the development of modelling techniques used to study the dynamics of the plasma implosion process and the role of instabilities. Interaction between analytic techniques and detailed numerical simulation has led to improvement in all theoretical modeling techniques presently used to study the implosion process. Comparisons of implosion times, shell structure, instability growth rates, and thermalization times have shown good agreement between analytic/heuristic techniques and more detailed two dimensional magnetohydrodynamic simulations. These in turn have provided excellent agreement with experimental results for both capacitor and inductor pulse power systems.
Modeling business processes: theoretical and practical aspects
V.V. Dubininа
2015-06-01
Full Text Available The essence of process-oriented enterprise management has been examined in the article. The content and types of information technology have been analyzed in the article, due to the complexity and differentiation of existing methods, as well as the specificity of language, terminology of the enterprise business processes modeling. The theoretical aspects of business processes modeling have been reviewed and the modern traditional modeling techniques received practical application in the visualization model of retailers activity have been studied in the article. In the process of theoretical analysis of the modeling methods found that UFO-toolkit method that has been developed by Ukrainian scientists due to it systemology integrated opportunities, is the most suitable for structural and object analysis of retailers business processes. It was designed visualized simulation model of the business process "sales" as is" of retailers using a combination UFO-elements with the aim of the further practical formalization and optimization of a given business process.
Advances in theoretical models of network science
FANG Jin-qing; BI Qiao; LI Yong
2007-01-01
In this review article, we will summarize the main advances in network science investigated by the CIAE Group of Complex Network in this field. Several theoretical models of network science were proposed and their topological and dynamical properties are reviewed and compared with the other models. Our models mainly include a harmonious unifying hybrid preferential model, a large unifying hybrid network model, a quantum interference network, a hexagonal nanowire network, and a small-world network with the same degree. The models above reveal some new phenomena and findings, which are useful for deeply understanding and investigating complex networks and their applications.
A theoretical model of multielectrode DBR lasers
Pan, Xing; Olesen, Henning; Tromborg, Bjarne
1988-01-01
A theoretical model for two- and three-section tunable distributed Bragg reflector (DBR) lasers is presented. The static tuning properties are studied in terms of threshold current, linewidth, oscillation frequency, and output power. Regions of continuous tuning for three-section DBR lasers...
Some Model Theoretic Remarks on Bass Modules
E. Momtahan
2011-09-01
Full Text Available We study Bass modules, Bass rings, and related concepts from a model theoretic point of view. We observe that the class of Bass modules (over a fixed ring is not stable under elementary equivalence. We observe that under which conditions the class of Bass rings are stable under elementary equivalence.
Hybrid quantum teleportation: A theoretical model
Takeda, Shuntaro; Mizuta, Takahiro; Fuwa, Maria; Yoshikawa, Jun-ichi; Yonezawa, Hidehiro; Furusawa, Akira [Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)
2014-12-04
Hybrid quantum teleportation – continuous-variable teleportation of qubits – is a promising approach for deterministically teleporting photonic qubits. We propose how to implement it with current technology. Our theoretical model shows that faithful qubit transfer can be achieved for this teleportation by choosing an optimal gain for the teleporter’s classical channel.
[Holism in theoretical models of nursing].
Neto, D L; da Nóbrega, M M
1999-01-01
In this bibliographical analysis, we present the classification of nine theoretical nursing models which frame holistic thinking according to the school of thought of Human Needs, Interaction and Outcome. It further describes the definition of holism, health, client and nursing in the holistic conception, with the objective of portraying holism in the theoretical references of nursing: The Ambiental Theory of Nightingale, the Interpersonal Theory of Peplau, the Philosophical Theory of Hall, The Theory of Basics Principals of Henderson, the Theory of Self Care of Orem, the Prescriptive Theory of Wiedenbach, the Theory of Basic Needs of Horta, the Theory of Adaptation of Roy and the Theory of Holism of Levine.
Error Estimates of Theoretical Models: a Guide
Dobaczewski, J; Reinhard, P -G
2014-01-01
This guide offers suggestions/insights on uncertainty quantification of nuclear structure models. We discuss a simple approach to statistical error estimates, strategies to assess systematic errors, and show how to uncover inter-dependencies by correlation analysis. The basic concepts are illustrated through simple examples. By providing theoretical error bars on predicted quantities and using statistical methods to study correlations between observables, theory can significantly enhance the feedback between experiment and nuclear modeling.
Theoretical model of smooth disk operation
Krauze, K.
1985-02-01
Aes a theoretical model is analyzed for coal cutting by disk cutters mounted on a helical cutting drum of a shearer loader. The model is based on the assumption that failure of coal cohesion is caused by crushing and separation of coal grains from a coal face and that coal cutting resistance depends on its contact strength as well as cutting depth and cutting angle. 1 reference.
Modelling in Accounting. Theoretical and Practical Dimensions
Teresa Szot-Gabryś
2010-10-01
Full Text Available Accounting in the theoretical approach is a scientific discipline based on specific paradigms. In the practical aspect, accounting manifests itself through the introduction of a system for measurement of economic quantities which operates in a particular business entity. A characteristic of accounting is its flexibility and ability of adaptation to information needs of information recipients. One of the main currents in the development of accounting theory and practice is to cover by economic measurements areas which have not been hitherto covered by any accounting system (it applies, for example, to small businesses, agricultural farms, human capital, which requires the development of an appropriate theoretical and practical model. The article illustrates the issue of modelling in accounting based on the example of an accounting model developed for small businesses, i.e. economic entities which are not obliged by law to keep accounting records.
Theoretical Model of Steel Continuous Casting Technology
C Gheorghies; I Crudu; C Teletin; C Spanu
2009-01-01
A theoretical model adapted for studying steel continuous casting technology was proposed.The model based on system theory contained input/output,command,and control parameters.The process was divided into five stages,i.e.,tundish,mold,guiding system,guiding-drawing system,and guiding-drawing-soft reduction system.The model can be used to describe the physicoehemical processes,thermal processes,chemical processes,and characteristics of the cast material according to the above-mentioned stages.It can also be applied to other metallurgical technologies and even to other industries (chemistry,food,etc.).
Numerical modelling of corrosion - Theoretical backgrounds -
Warkus, J.; Raupach, M. [ibac, RWTH Aachen (Germany); Gulikers, J. [Ministry of Transport, Rijkswaterstaat, Bouwdienst, Utrecht (Netherlands)
2006-08-15
During recent years research projects with different approaches have been carried out to develop models which are suitable to assess the metal removal rate in case of reinforcement corrosion. Some of them are based on empirical methods and correlate the corrosion rate to parameters like concrete resistivity, temperature and relative humidity. Another type of model is based on a quantification of the ongoing electrochemical processes. In this paper the theoretical backgrounds and mathematical descriptions of reinforcement corrosion with regard to a numerical modelling are presented and discussed. (Abstract Copyright [2006], Wiley Periodicals, Inc.)
Theoretical aspects of spatial-temporal modeling
Matsui, Tomoko
2015-01-01
This book provides a modern introductory tutorial on specialized theoretical aspects of spatial and temporal modeling. The areas covered involve a range of topics which reflect the diversity of this domain of research across a number of quantitative disciplines. For instance, the first chapter provides up-to-date coverage of particle association measures that underpin the theoretical properties of recently developed random set methods in space and time otherwise known as the class of probability hypothesis density framework (PHD filters). The second chapter gives an overview of recent advances in Monte Carlo methods for Bayesian filtering in high-dimensional spaces. In particular, the chapter explains how one may extend classical sequential Monte Carlo methods for filtering and static inference problems to high dimensions and big-data applications. The third chapter presents an overview of generalized families of processes that extend the class of Gaussian process models to heavy-tailed families known as alph...
Electromechanical properties of smart aggregate: theoretical modeling and experimental validation
Wang, Jianjun; Kong, Qingzhao; Shi, Zhifei; Song, Gangbing
2016-09-01
Smart aggregate (SA), as a piezoceramic-based multi-functional device, is formed by sandwiching two lead zirconate titanate (PZT) patches with copper shielding between a pair of solid-machined cylindrical marble blocks with epoxy. Previous researches have successfully demonstrated the capability and reliability of versatile SAs to monitor the structural health of concrete structures. However, the previous works concentrated mainly on the applications of SAs in structural health monitoring; no reasonable theoretical model of SAs was proposed. In this paper, electromechanical properties of SAs were investigated using a proposed theoretical model. Based on one dimensional linear theory of piezo-elasticity, the dynamic solutions of a SA subjected to an external harmonic voltage were solved. Further, the electric impedance of the SA was computed, and the resonance and anti-resonance frequencies were calculated based on derived equations. Numerical analysis was conducted to discuss the effects of the thickness of epoxy layer and the dimension of PZT patch on the fundamental resonance and anti-resonance frequencies as well as the corresponding electromechanical coupling factor. The dynamic solutions based on the proposed theoretical model were further experimentally verified with two SA samples. The fundamental resonance and anti-resonance frequencies of SAs show good agreements in both theoretical and experimental results. The presented analysis and results contribute to the overall understanding of SA properties and help to optimize the working frequencies of SAs in structural health monitoring of civil structures.
A theoretical model of metal surface reactions
Shustorovich, E. (Eastman Kodak Co., Rochester, NY); Baetzold, R.C.; Muetterties, E.L.
1983-03-31
Metal surface reactions are modeled with a novel theoretical construct in which periodic trends can be scrutinized. The theoretical model is succinctly presented and a conspectus of periodic trends, based on the model, is explored. Periodic trends are discussed in the contexts of chemisorption bond energies, electron transfer between metal surface and adsorbate, stereochemical features of chemisorption states for closed-shell diatomic and linear X-CN or X-NC molecules, and hydrocarbon reactions. Hydrocarbon C-H bond-breaking processes are analyzed in terms of d-level occupancy, electron transfer, and stereochemistry of intermediates. Conceptually and computationally, the metal surface is characterized as a good electron donor: antibonding molecular orbitals of the adsorbate species appear to be significant contributors to the chemisorption bond and also play a decisive role in bond-breaking processes. No aspect of the model projections is inconsistent with the experimental data although the electronic characterization of some chemisorption states are counter to commonly held perceptions.
A Theoretical Model of Water and Trade
Dang, Q.; Konar, M.; Reimer, J.; Di Baldassarre, G.; Lin, X.; Zeng, R.
2015-12-01
Water is an essential factor of agricultural production. Agriculture, in turn, is globalized through the trade of food commodities. In this paper, we develop a theoretical model of a small open economy that explicitly incorporates water resources. The model emphasizes three tradeoffs involving water decision-making that are important yet not always considered within the existing literature. One tradeoff focuses on competition for water among different sectors when there is a shock to one of the sectors only, such as trade liberalization and consequent higher demand for the product. A second tradeoff concerns the possibility that there may or may not be substitutes for water, such as increased use of sophisticated irrigation technology as a means to increase crop output in the absence of higher water availability. A third tradeoff explores the possibility that the rest of the world can be a source of supply or demand for a country's water-using products. A number of propositions are proven. For example, while trade liberalization tends to increase water use, increased pressure on water supplies can be moderated by way of a tax that is derivable with observable economic phenomena. Another example is that increased riskiness of water availability tends to cause water users to use less water than would be the case under profit maximization. These theoretical model results generate hypotheses that can be tested empirically in future work.
Electron microscopy and theoretical modeling of cochleates.
Nagarsekar, Kalpa; Ashtikar, Mukul; Thamm, Jana; Steiniger, Frank; Schacher, Felix; Fahr, Alfred; May, Sylvio
2014-11-11
Cochleates are self-assembled cylindrical condensates that consist of large rolled-up lipid bilayer sheets and represent a novel platform for oral and systemic delivery of therapeutically active medicinal agents. With few preceding investigations, the physical basis of cochleate formation has remained largely unexplored. We address the structure and stability of cochleates in a combined experimental/theoretical approach. Employing different electron microscopy methods, we provide evidence for cochleates consisting of phosphatidylserine and calcium to be hollow tubelike structures with a well-defined constant lamellar repeat distance and statistically varying inner and outer radii. To rationalize the relation between inner and outer radii, we propose a theoretical model. Based on the minimization of a phenomenological free energy expression containing a bending, adhesion, and frustration contribution, we predict the optimal tube dimensions of a cochleate and estimate ratios of material constants for cochleates consisting of phosphatidylserines with varied hydrocarbon chain structures. Knowing and understanding these ratios will ultimately benefit the successful formulation of cochleates for drug delivery applications.
Theoretical model of a photoelectrochemical solar cell
Chandra, S.; Singh, S.L.; Khare, N.
1986-03-01
A Schottky barrier theoretical model for explaining the J-V characteristic of a photoelectrochemical solar cell (PESC) has been developed considering the effect of dark current, space-charge recombination, surface states, and detailed charge transfer kinetics at the interface. Both isoenergetic charge transfer and inelastic charge transfers (via surface states) at the interface have been considered and their relative importance are discussed. The theory has been applied to explain the (a) J-V characteristic for n-GaAs/SeS , SeS 2 junction and (b) Fermi-level pinning observed in GaAs PESC. The inelastic charge transfer via surfaces states has been shown to play an important role in deciding these characteristics.
Effectiveness of Peer Education Involving the use of Theoretical Models
2008-01-01
The effectiveness of health education among university students who received peer-support training was investigated using four theoretical models : the health belief model, the self-efficacy model, social support and the transtheoretical model of health behavior change. Results suggested that the four theoretical models were useful in evaluating the effect of peer education as an alternative assessment tool. In light of this, it is suggested that the use of the theoretical models may facilita...
The truncation of stellar discs A theoretical model
Battaner, E; Jiménez-Vicente, J
1998-01-01
The truncation of stellar discs is not abrupt but characterized by a continuous distancing from the exponential profile. There exists a truncation curve, $t(r)$, ending at a truncation radius, $r_t$. We present here a theoretical model in which it is assumed that the magnetic hypothesis explaining the flat rotation curve also explains the truncation. Once stars are born, the centripetal magnetic force previously acting on the progenitor gas cloud is suddenly interrupted, and stars must move to larger orbits or escape. The agreement between theoretical and observed truncation curves is very satisfactory. Parameters defining the disc gas rotation curve should therefore be related to those defining the truncation. It is predicted that rotation curves that quickly reach the asymptotic value $\\theta_0 = \\theta (r=\\infty)$ would have small truncation radii. On the contrary, $r_t$ and $\\theta_0$ itself, would be uncorrelated quantities.
Information-Theoretic Perspectives on Geophysical Models
Nearing, Grey
2016-04-01
practice of science (except by Gong et al., 2013, whose fundamental insight is the basis for this talk), and here I offer two examples of practical methods that scientists might use to approximately measure ontological information. I place this practical discussion in the context of several recent and high-profile experiments that have found that simple out-of-sample statistical models typically (vastly) outperform our most sophisticated terrestrial hydrology models. I offer some perspective on several open questions about how to use these findings to improve our models and understanding of these systems. Cartwright, N. (1983) How the Laws of Physics Lie. New York, NY: Cambridge Univ Press. Clark, M. P., Kavetski, D. and Fenicia, F. (2011) 'Pursuing the method of multiple working hypotheses for hydrological modeling', Water Resources Research, 47(9). Cover, T. M. and Thomas, J. A. (1991) Elements of Information Theory. New York, NY: Wiley-Interscience. Cox, R. T. (1946) 'Probability, frequency and reasonable expectation', American Journal of Physics, 14, pp. 1-13. Csiszár, I. (1972) 'A Class of Measures of Informativity of Observation Channels', Periodica Mathematica Hungarica, 2(1), pp. 191-213. Davies, P. C. W. (1990) 'Why is the physical world so comprehensible', Complexity, entropy and the physics of information, pp. 61-70. Gong, W., Gupta, H. V., Yang, D., Sricharan, K. and Hero, A. O. (2013) 'Estimating Epistemic & Aleatory Uncertainties During Hydrologic Modeling: An Information Theoretic Approach', Water Resources Research, 49(4), pp. 2253-2273. Jaynes, E. T. (2003) Probability Theory: The Logic of Science. New York, NY: Cambridge University Press. Nearing, G. S. and Gupta, H. V. (2015) 'The quantity and quality of information in hydrologic models', Water Resources Research, 51(1), pp. 524-538. Popper, K. R. (2002) The Logic of Scientific Discovery. New York: Routledge. Van Horn, K. S. (2003) 'Constructing a logic of plausible inference: a guide to cox's theorem
Improving statistical reasoning theoretical models and practical implications
Sedlmeier, Peter
1999-01-01
This book focuses on how statistical reasoning works and on training programs that can exploit people''s natural cognitive capabilities to improve their statistical reasoning. Training programs that take into account findings from evolutionary psychology and instructional theory are shown to have substantially larger effects that are more stable over time than previous training regimens. The theoretical implications are traced in a neural network model of human performance on statistical reasoning problems. This book apppeals to judgment and decision making researchers and other cognitive scientists, as well as to teachers of statistics and probabilistic reasoning.
2010-01-04
... Directives; Bombardier, Inc. (Type Certificate Previously Held by Canadair) Model CL-600-2B16 (CL-604...: Bombardier, Inc. (Type Certificate Previously Held by Canadair): Docket No. FAA-2009-1227; Directorate... (b) None. Applicability (c) This AD applies to Bombardier, Inc. (Type Certificate previously held...
How prayer heals: a theoretical model.
Levin, J S
1996-01-01
This article presents a theoretical model that outlines various possible explanations for the healing effects of prayer. Four classes of mechanisms are defined on the basis of whether healing has naturalistic or supernatural origins and whether it operates locally or nonlocally. Through this framework, most of the currently proposed hypotheses for understanding absent healing and other related phenomena-hypotheses that invoke such concepts as subtle energy, psi, consciousness, morphic fields, and extended mind-are shown to be no less naturalistic than the Newtonian, mechanistic forces of allopathic biomedicine so often derided for their materialism. In proposing that prayer may heal through nonlocal means according to mechanisms and theories proposed by the new physics, Dossey is almost alone among medical scholars in suggesting the possible limitations and inadequacies of hypotheses based on energies, forces, and fields. Yet even such nonlocal effects can be conceived of as naturalistic; that is, they are explained by physical laws that may be unbelievable or unfamiliar to most physicians but that are nonetheless becoming recognized as operant laws of the natural universe. The concept of the supernatural, however, is something altogether different, and is, by definition, outside of or beyond nature. Herein may reside an either wholly or partly transcendent Creator-God who is believed by many to heal through means that transcend the laws of the created universe, both its local and nonlocal elements, and that are thus inherently inaccessible to and unknowable by science. Such an explanation for the effects of prayer merits consideration and, despite its unprovability by medical science, should not be dismissed out of hand.
Theoretical Tinnitus framework: A Neurofunctional Model
Iman Ghodratitoostani
2016-08-01
Full Text Available Subjective tinnitus is the conscious (attended awareness perception of sound in the absence of an external source and can be classified as an auditory phantom perception. The current tinnitus development models depend on the role of external events congruently paired with the causal physical events that precipitate the phantom perception. We propose a novel Neurofunctional tinnitus model to indicate that the conscious perception of phantom sound is essential in activating the cognitive-emotional value. The cognitive-emotional value plays a crucial role in governing attention allocation as well as developing annoyance within tinnitus clinical distress. Structurally, the Neurofunctional tinnitus model includes the peripheral auditory system, the thalamus, the limbic system, brain stem, basal ganglia, striatum and the auditory along with prefrontal cortices. Functionally, we assume the model includes presence of continuous or intermittent abnormal signals at the peripheral auditory system or midbrain auditory paths. Depending on the availability of attentional resources, the signals may or may not be perceived. The cognitive valuation process strengthens the lateral-inhibition and noise canceling mechanisms in the mid-brain, which leads to the cessation of sound perception and renders the signal evaluation irrelevant. However, the sourceless sound is eventually perceived and can be cognitively interpreted as suspicious or an indication of a disease in which the cortical top-down processes weaken the noise canceling effects. This results in an increase in cognitive and emotional negative reactions such as depression and anxiety. The negative or positive cognitive-emotional feedbacks within the top-down approach may have no relation to the previous experience of the patients. They can also be associated with aversive stimuli similar to abnormal neural activity in generating the phantom sound. Cognitive and emotional reactions depend on general
Theoretical Tinnitus Framework: A Neurofunctional Model.
Ghodratitoostani, Iman; Zana, Yossi; Delbem, Alexandre C B; Sani, Siamak S; Ekhtiari, Hamed; Sanchez, Tanit G
2016-01-01
Subjective tinnitus is the conscious (attended) awareness perception of sound in the absence of an external source and can be classified as an auditory phantom perception. Earlier literature establishes three distinct states of conscious perception as unattended, attended, and attended awareness conscious perception. The current tinnitus development models depend on the role of external events congruently paired with the causal physical events that precipitate the phantom perception. We propose a novel Neurofunctional Tinnitus Model to indicate that the conscious (attended) awareness perception of phantom sound is essential in activating the cognitive-emotional value. The cognitive-emotional value plays a crucial role in governing attention allocation as well as developing annoyance within tinnitus clinical distress. Structurally, the Neurofunctional Tinnitus Model includes the peripheral auditory system, the thalamus, the limbic system, brainstem, basal ganglia, striatum, and the auditory along with prefrontal cortices. Functionally, we assume the model includes presence of continuous or intermittent abnormal signals at the peripheral auditory system or midbrain auditory paths. Depending on the availability of attentional resources, the signals may or may not be perceived. The cognitive valuation process strengthens the lateral-inhibition and noise canceling mechanisms in the mid-brain, which leads to the cessation of sound perception and renders the signal evaluation irrelevant. However, the "sourceless" sound is eventually perceived and can be cognitively interpreted as suspicious or an indication of a disease in which the cortical top-down processes weaken the noise canceling effects. This results in an increase in cognitive and emotional negative reactions such as depression and anxiety. The negative or positive cognitive-emotional feedbacks within the top-down approach may have no relation to the previous experience of the patients. They can also be
Explaining clinical behaviors using multiple theoretical models.
Eccles, Martin P; Grimshaw, Jeremy M; MacLennan, Graeme; Bonetti, Debbie; Glidewell, Liz; Pitts, Nigel B; Steen, Nick; Thomas, Ruth; Walker, Anne; Johnston, Marie
2012-10-17
In the field of implementation research, there is an increased interest in use of theory when designing implementation research studies involving behavior change. In 2003, we initiated a series of five studies to establish a scientific rationale for interventions to translate research findings into clinical practice by exploring the performance of a number of different, commonly used, overlapping behavioral theories and models. We reflect on the strengths and weaknesses of the methods, the performance of the theories, and consider where these methods sit alongside the range of methods for studying healthcare professional behavior change. These were five studies of the theory-based cognitions and clinical behaviors (taking dental radiographs, performing dental restorations, placing fissure sealants, managing upper respiratory tract infections without prescribing antibiotics, managing low back pain without ordering lumbar spine x-rays) of random samples of primary care dentists and physicians. Measures were derived for the explanatory theoretical constructs in the Theory of Planned Behavior (TPB), Social Cognitive Theory (SCT), and Illness Representations specified by the Common Sense Self Regulation Model (CSSRM). We constructed self-report measures of two constructs from Learning Theory (LT), a measure of Implementation Intentions (II), and the Precaution Adoption Process. We collected data on theory-based cognitions (explanatory measures) and two interim outcome measures (stated behavioral intention and simulated behavior) by postal questionnaire survey during the 12-month period to which objective measures of behavior (collected from routine administrative sources) were related. Planned analyses explored the predictive value of theories in explaining variance in intention, behavioral simulation and behavior. Response rates across the five surveys ranged from 21% to 48%; we achieved the target sample size for three of the five surveys. For the predictor variables
Explaining clinical behaviors using multiple theoretical models
Eccles Martin P
2012-10-01
Full Text Available Abstract Background In the field of implementation research, there is an increased interest in use of theory when designing implementation research studies involving behavior change. In 2003, we initiated a series of five studies to establish a scientific rationale for interventions to translate research findings into clinical practice by exploring the performance of a number of different, commonly used, overlapping behavioral theories and models. We reflect on the strengths and weaknesses of the methods, the performance of the theories, and consider where these methods sit alongside the range of methods for studying healthcare professional behavior change. Methods These were five studies of the theory-based cognitions and clinical behaviors (taking dental radiographs, performing dental restorations, placing fissure sealants, managing upper respiratory tract infections without prescribing antibiotics, managing low back pain without ordering lumbar spine x-rays of random samples of primary care dentists and physicians. Measures were derived for the explanatory theoretical constructs in the Theory of Planned Behavior (TPB, Social Cognitive Theory (SCT, and Illness Representations specified by the Common Sense Self Regulation Model (CSSRM. We constructed self-report measures of two constructs from Learning Theory (LT, a measure of Implementation Intentions (II, and the Precaution Adoption Process. We collected data on theory-based cognitions (explanatory measures and two interim outcome measures (stated behavioral intention and simulated behavior by postal questionnaire survey during the 12-month period to which objective measures of behavior (collected from routine administrative sources were related. Planned analyses explored the predictive value of theories in explaining variance in intention, behavioral simulation and behavior. Results Response rates across the five surveys ranged from 21% to 48%; we achieved the target sample size for three of
Theoretical and experimental FUZZY modelling of building thermal dynamic response
Skrjanc, Igor; Zupancic, Borut [Ljubljana Univ., Faculty of Electrical Engineering, Ljubljana (Slovenia); Furlan, Bostjan; Krainer, Ales [Ljubljana Univ., Faculty of Civil Engineering, Ljubljana (Slovenia)
2001-11-01
In this paper this main advantages and disadvantages of two different types of modelling: theoretical and experimental are presented and discussed. The theoretical modelling is based on energy balances, which gives the overall model described by differential equations. On the basis of developed theoretical model a complex simulator in the MATLAB-Simulink environment was implemented. The second part is devoted to experimental modelling. In this paper a fuzzy model represented by non-linear relations between input and output variables obtained by least-squares optimisation method is investigated. (Author)
A theoretical model of atmospheric ozone depletion
Midya, S. K.; Jana, P. K.; Lahiri, T.
1994-01-01
A critical study on different ozone depletion and formation processes has been made and following important results are obtained: (i) From analysis it is shown that O3 concentration will decrease very minutely with time for normal atmosphere when [O], [O2] and UV-radiation remain constant. (ii) An empirical equation is established theoretically between the variation of ozone concentration and time. (iii) Special ozone depletion processes are responsible for the dramatic decrease of O3-concentration at Antarctica.
High Tc Superconductor Theoretical Models and Electromagnetic Flux Characteristics
JIN Jian-xun
2006-01-01
High Tc Superconductors (HTS) have special electromagnetic characteristics and phenomena. Effort has been made in order to theoretically understand the applied HTS superconductivity and HTS behaviors for practical applications, various theoretical models related to the HTS electromagnetic properties have been developed. The theoretical models and analytic methods are summarized with regard to understanding the HTS magnetic flux characteristic which is one of the most critical issues related to HTS applications such as for HTS magnetic levitation application.
Modeling of alkynes: synthesis and theoretical properties
Renato Rosseto
2003-06-01
Full Text Available In this paper we present the synthesis and simulation of alkynes derivatives. Semiempirical calculations were carried out for the ground and first excited states, including the spectroscopic properties of the absorption and emission (fluorescence and phosphorescence spectra by INDO/S-CI and DNdM-INDO/S-CI methods with geometries fully optimized by PM3/CI. The fact that the theoretical spectra are in accord with the experimental absorption spectra gives us a new possible approach on how structure modifications could affect the non-linear optical properties of alkynes.
Organizational effectiveness of coalition operations' headquarters : A theoretical model
Vogler-Bisig, E.; Blais, A.R.; Hof, T.; Tresch, T.S.; Seiler, S.; Yanakiev, Y.
2012-01-01
Purpose - This article describes a theoretical model that allows understanding, explaining, and measuring the perceived organizational effectiveness of multinational coalition operations' headquarters. Design/methodology/approach - The proposed model is based on subject matter experts' opinions and
POSITIVE LEADERSHIP MODELS: THEORETICAL FRAMEWORK AND RESEARCH
Javier Blanch, Francisco Gil
2016-09-01
Full Text Available The objective of this article is twofold; firstly, we establish the theoretical boundaries of positive leadership and the reasons for its emergence. It is related to the new paradigm of positive psychology that has recently been shaping the scope of organizational knowledge. This conceptual framework has triggered the development of the various forms of positive leadership (i.e. transformational, servant, spiritual, authentic, and positive. Although the construct does not seem univocally defined, these different types of leadership overlap and share a significant affinity. Secondly, we review the empirical evidence that shows the impact of positive leadership in organizations and we highlight the positive relationship between these forms of leadership and key positive organizational variables. Lastly, we analyse future research areas in order to further develop this concept.
Theoretical model of blood flow measurement by diffuse correlation spectroscopy
Sakadžić, Sava; Boas, David A.; Carp, Stefan
2017-02-01
Diffuse correlation spectroscopy (DCS) is a noninvasive method to quantify tissue perfusion from measurements of the intensity temporal autocorrelation function of diffusely scattered light. However, DCS autocorrelation function measurements in tissue better match theoretical predictions based on the diffusive motion of the scatterers than those based on a model where the advective nature of blood flow dominates the stochastic properties of the scattered light. We have recently shown using Monte Carlo (MC) simulations and assuming a simplistic vascular geometry and laminar flow profile that the diffusive nature of the DCS autocorrelation function decay is likely a result of the shear-induced diffusion of the red blood cells. Here, we provide theoretical derivations supporting and generalizing the previous MC results. Based on the theory of diffusing-wave spectroscopy, we derive an expression for the autocorrelation function along the photon path through a vessel that takes into account both diffusive and advective scatterer motion, and we provide the solution for the DCS autocorrelation function in a semi-infinite geometry. We also derive the correlation diffusion and correlation transfer equation, which can be applied for an arbitrary sample geometry. Further, we propose a method to take into account realistic vascular morphology and flow profile.
A Theoretic Model of Transport Logistics Demand
Natalija Jolić
2006-01-01
Full Text Available Concerning transport logistics as relation between transportand integrated approaches to logistics, some transport and logisticsspecialists consider the tenn tautological. However,transport is one of the components of logistics, along with inventories,resources, warehousing, infonnation and goods handling.Transport logistics considers wider commercial and operationalframeworks within which the flow of goods is plannedand managed. The demand for transport logistics services canbe valorised as highly qualitative, differentiated and derived.While researching transport phenomenon the implementationof models is inevitable and demand models highly desirable. Asa contribution to transport modelling this paper improves decisionmaking and planning in the transport logistics field.
Dark energy observational evidence and theoretical models
Novosyadlyj, B; Shtanov, Yu; Zhuk, A
2013-01-01
The book elucidates the current state of the dark energy problem and presents the results of the authors, who work in this area. It describes the observational evidence for the existence of dark energy, the methods and results of constraining of its parameters, modeling of dark energy by scalar fields, the space-times with extra spatial dimensions, especially Kaluza---Klein models, the braneworld models with a single extra dimension as well as the problems of positive definition of gravitational energy in General Relativity, energy conditions and consequences of their violation in the presence of dark energy. This monograph is intended for science professionals, educators and graduate students, specializing in general relativity, cosmology, field theory and particle physics.
Theoretical Modelling of Intercultural Communication Process
Mariia Soter
2016-08-01
Full Text Available The definition of the concepts of “communication”, “intercultural communication”, “model of communication” are analyzed in the article. The basic components of the communication process are singled out. The model of intercultural communication is developed. Communicative, behavioral and complex skills for optimal organization of intercultural communication, establishment of productive contact with a foreign partner to achieve mutual understanding, searching for acceptable ways of organizing interaction and cooperation for both communicants are highlighted in the article. It is noted that intercultural communication through interaction between people affects the development of different cultures’ aspects.
Theoretical analysis and modeling for nanoelectronics
Baccarani, Giorgio; Gnani, Elena; Gnudi, Antonio; Reggiani, Susanna
2016-11-01
In this paper we review the evolution of Microelectronics and its transformation into Nanoelectronics, following the predictions of Moore's law, and some of the issues related with this evolution. Next, we discuss the requirements of device modeling and the solutions proposed throughout the years to address the physical effects related with an extreme device miniaturization, such as hot-electron effects, band splitting into multiple sub-bands, quasi-ballistic transport and electron tunneling. The most important physical models are shortly highlighted, and a few simulation results of heterojunction TFETs are reported and discussed.
SOME THEORETICAL MODELS EXPLAINING ADVERTISING EFFECTS
Vasilica Magdalena SOMEŞFĂLEAN
2014-06-01
Full Text Available Persuade clients is still the main focus of the companies, using a set of methods and techniques designed to influence their behavior, in order to obtain better results (profits over a longer period of time. Since the late nineteenth - early twentieth century, the american E.St.Elmo Lewis, considered a pioneer in advertising and sales, developed the first theory, AIDA model, later used by marketers and advertisers to develop a marketing communications strategy. Later studies have developed other models that are the main subject of this research, which explains how and why persuasive communication works, to understand why some approaches are effective and others are not.
A Theoretical Model for Selective Exposure Research.
Roloff, Michael E.; Noland, Mark
This study tests the basic assumptions underlying Fishbein's Model of Attitudes by correlating an individual's selective exposure to types of television programs (situation comedies, family drama, and action/adventure) with the attitudinal similarity between individual attitudes and attitudes characterized on the programs. Twenty-three college…
The development of a theoretical model to investigate factors ...
The development of a theoretical model to investigate factors associated with ... major household appliance market: An integrative conceptual approach. ... disadvantaged consumers gain spending power and access to electricity supply.
Theoretical models in low-Reynolds-number locomotion
Pak, On Shun
2014-01-01
The locomotion of microorganisms in fluids is ubiquitous and plays an important role in numerous biological processes. In this chapter we present an overview of theoretical modeling for low-Reynolds-number locomotion.
Theoretical model for a Stark anomalous dispersion optical filter
Yin, B.; Shay, T. M.
1993-01-01
A theoretical model for the first atomic Stark anomalous dispersion optical filter is reported. The results show the filter may serve as a widely tunable narrow bandwidth and high throughput optical filter for freespace laser communications and remote sensing.
A Theoretical Study of Subsurface Drainage Model Simulation of ...
A Theoretical Study of Subsurface Drainage Model Simulation of Drainage Flow and ... of subsurface drain spacing, evapotranspiration and irrigation water quality on ... The study was carried out on a conceptual uniform homogenous irrigated ...
Theoretical Models of the Galactic Bulge
Shen, Juntai
2015-01-01
Near infrared images from the COBE satellite presented the first clear evidence that our Milky Way galaxy contains a boxy shaped bulge. Recent years have witnessed a gradual paradigm shift in the formation and evolution of the Galactic bulge. Bulges were commonly believed to form in the dynamical violence of galaxy mergers. However, it has become increasingly clear that the main body of the Milky Way bulge is not a classical bulge made by previous major mergers, instead it appears to be a bar seen somewhat end-on. The Milky Way bar can form naturally from a precursor disk and thicken vertically by the internal firehose/buckling instability, giving rise to the boxy appearance. This picture is supported by many lines of evidence, including the asymmetric parallelogram shape, the strong cylindrical rotation (i.e., nearly constant rotation regardless of the height above the disk plane), the existence of an intriguing X-shaped structure in the bulge, and perhaps the metallicity gradients. We review the major theor...
Choking under pressure: theoretical models and interventions.
Mesagno, Christopher; Beckmann, Juergen
2017-08-01
In sport, choking under pressure is a major concern for athletes, coaches and sport psychologists because athletes fail to meet self-imposed performance expectations in critical situations (when it counts the most), which is devastating and embarrassing. Researchers have debated choking under pressure definitions, identified personality characteristics that exacerbate choking outcomes, and examined models to determine mechanisms for choking. Based on these investigations, several interventions to prevent choking have been developed and tested. In this review, we specifically discuss current self-presentation and attention models and theory-driven interventions that help to alleviate choking in order to facilitate the understanding of this complex phenomenon by athletes, sport psychologists and researchers. Copyright © 2017 Elsevier Ltd. All rights reserved.
SOME THEORETICAL MODELS EXPLAINING ADVERTISING EFFECTS
Vasilica Magdalena SOMEŞFĂLEAN
2014-01-01
Persuade clients is still the main focus of the companies, using a set of methods and techniques designed to influence their behavior, in order to obtain better results (profits) over a longer period of time. Since the late nineteenth - early twentieth century, the american E.St.Elmo Lewis, considered a pioneer in advertising and sales, developed the first theory, AIDA model, later used by marketers and advertisers to develop a marketing communications strategy. Later studies have developed o...
Theoretical modeling of prion disease incubation
Kulkarni, R. V.; Slepoy, A.; Singh, R. R. P.; Cox, D. L.; Mobley, D.; Pázmándi, F.
2001-01-01
We present a theory for the laboratory and epidemiological data for incubation times in infectious prion diseases. The central feature of our model is that slow growth of misfolded protein-aggregates from small initial seeds controls the `latent' or `lag' phase, whereas aggregate-fissioning and subsequent spreading leads to an exponential growth or doubling phase. Such a general framework can account for many features of prion diseases including the striking reproducibility of incubation time...
A theoretical model of infant incubator dynamics.
Simon, B N; Reddy, N P; Kantak, A
1994-08-01
A spatially lumped mathematical model was developed and used for a computer simulation of the neonate-incubator system for parametric analysis of the factors that influence neonatal thermo-regulation. The simulation examined the effects of the following parameters: (1) size of the infant; (2) respiratory rate; (3) metabolic rate; (4) heart rate; (5) thermal properties of the mattress; (6) specific heat capacity of the incubator wall; (7) air flow rate; (8) heater control mechanisms.
Voronoi cell patterns: Theoretical model and applications
González, Diego Luis; Einstein, T. L.
2011-11-01
We use a simple fragmentation model to describe the statistical behavior of the Voronoi cell patterns generated by a homogeneous and isotropic set of points in 1D and in 2D. In particular, we are interested in the distribution of sizes of these Voronoi cells. Our model is completely defined by two probability distributions in 1D and again in 2D, the probability to add a new point inside an existing cell and the probability that this new point is at a particular position relative to the preexisting point inside this cell. In 1D the first distribution depends on a single parameter while the second distribution is defined through a fragmentation kernel; in 2D both distributions depend on a single parameter. The fragmentation kernel and the control parameters are closely related to the physical properties of the specific system under study. We use our model to describe the Voronoi cell patterns of several systems. Specifically, we study the island nucleation with irreversible attachment, the 1D car-parking problem, the formation of second-level administrative divisions, and the pattern formed by the Paris Métro stations.
Confronting Substellar Theoretical Models with Stellar Ages
Dupuy, Trent J; Ireland, Michael J
2009-01-01
By definition, brown dwarfs never reach the main-sequence, cooling and dimming over their entire lifetime, thus making substellar models challenging to test because of the strong dependence on age. Currently, most brown dwarfs with independently determined ages are companions to nearby stars, so stellar ages are at the heart of the effort to test substellar models. However, these models are only fully constrained if both the mass and age are known. We have used the Keck adaptive optics system to monitor the orbit of HD 130948BC, a brown dwarf binary that is a companion to the young solar analog HD 130948A. The total dynamical mass of 0.109+/-0.003 Msun shows that both components are substellar, and the ensemble of available age indicators from the primary star suggests an age comparable to the Hyades, with the most precise age being 0.79 Gyr based on gyrochronology. Therefore, HD 130948BC is unique among field L and T dwarfs as it possesses a well-determined mass, luminosity, and age. Our results indicate tha...
A Game Theoretic Model Of Strategic Conflict In Cyberspace
2012-01-01
by Shiva , Dasgupta, and Wu (2010). They develop a taxonomy of game theoretic models with two broad categories: Static versus Dynamic. A “one shot...to date on cyber conflict deals only with noncooperative games. In the taxonomy of Shiva et al. (2010) our proposed model is a noncooperative, dynamic...approach for cyber situational awareness. SPIE’s Defense and Security Symposium, Orlando, FL. Shiva , S., Dasgupta, D., & Wu, O. (2010). Game theoretic
Theoretical Modelling of Sound Radiation from Plate
Zaman, I.; Rozlan, S. A. M.; Yusoff, A.; Madlan, M. A.; Chan, S. W.
2017-01-01
Recently the development of aerospace, automotive and building industries demands the use of lightweight materials such as thin plates. However, the plates can possibly add to significant vibration and sound radiation, which eventually lead to increased noise in the community. So, in this study, the fundamental concept of sound pressure radiated from a simply-supported thin plate (SSP) was analyzed using the derivation of mathematical equations and numerical simulation of ANSYS®. The solution to mathematical equations of sound radiated from a SSP was visualized using MATLAB®. The responses of sound pressure level were measured at far field as well as near field in the frequency range of 0-200 Hz. Result shows that there are four resonance frequencies; 12 Hz, 60 Hz, 106 Hz and 158 Hz were identified which represented by the total number of the peaks in the frequency response function graph. The outcome also indicates that the mathematical derivation correlated well with the simulation model of ANSYS® in which the error found is less than 10%. It can be concluded that the obtained model is reliable and can be applied for further analysis such as to reduce noise emitted from a vibrating thin plate.
Theoretical postulation of PLC channel model
Alexandru Ionuţ Chiuţă
2009-05-01
Full Text Available The objective of this document is to supply atheoretical basis for modelling the communicationlinks over powerlines. A comprehensive summary oftransmission properties and the noise scenario onpublic mains supply when used for data transmissionare given.Different PLC models - PLC channel, noise inPLC channel, coupling units, filters and conditioningdevices – will be created and they will be used tosimulate the PLC channel.PLC applications will have to work at veryunusual channels, solely designed for optimalelectrical power transportation, completelydisregarding signal transmission at high frequencies.It is shown that the typical properties aredescribed by transfer functions and noise scenariostypical for access and inhouse networks. The generaltransfer function for different channel types is derivedand, since an emulation system should reproducetypical classes of channels rather than singlemeasurements, the transfer function is concretisedwith reference channels. These are later serving asbasis for development of channel simulators andchannel emulators. Special attention is paid tomodelling of aperiodic impulsive noise since PLCsystems are reacting very sensitive to them and thisclass of noise has been insufficiently considered so far.
From theoretical model to practical use:
Bjørk, Ida Torunn; Lomborg, Kirsten; Nielsen, Carsten Munch
2013-01-01
passive diffusion strategies with interaction and teamwork between stakeholders. The use of knowledge creates feedback that might have consequences for the refinement and tailoring of that same knowledge itself. With end-users in mind, several heuristics were used by the research group to increase clarity...... of the model and to tailor the implementation of knowledge to the users. Implications for nursing. This article illustrates the need for enduring collaboration between stakeholders to promote the process of knowledge translation. Translation of research knowledge into practice is a time-consuming process...... that is enhanced when appropriate support is given by leaders in the involved facilities. Conclusion. Knowledge translation is a time-consuming and collaborative endeavour. On the basis of our experience we advocate the implementation and use of a conceptual framework for the entire process of knowledge...
Theoretical model and quantification of reflectance photometer
Lihua Huang; Youbao Zhang; Chengke Xie; Jianfeng Qu; Huijie Huang; Xiangzhao Wang
2009-01-01
@@ The surface morphology of lateral flow (LF) strip is examined by scanning electron microscope (SEM) and the diffuse reflection of porous strip with or without nanogold particles is investigated.Based on the scattering and absorption of nanogold particles, a reflectance photometer is developed for quantification of LF strip with nanogold particles as reporter.The integration of reflection optical density is to indicate the signals of test line and control line.As an example, serial dilutions of microalbunminuria (MAU) solution are used to calibrate the performance of the reflectance photometer.The dose response curve is fitted with a four-parameter logistic mathematical model for the determination of an unknown MAU concentration.The response curve spans a dynamic range of 5 to 200 μg/ml.The developed reflectance photometer can realize simple and quantitative detection of analyte on nanogold-labeled LF strip.
The Psychopathological Model of Mental Retardation: Theoretical and Therapeutic Considerations.
La Malfa, Giampaolo; Campigli, Marco; Bertelli, Marco; Mangiapane, Antonio; Cabras, Pier Luigi
1997-01-01
Describes a new integrated bio-psycho-social model of etiology for mental retardation. Discusses the problems with current models and the ability of the "universe line" model to integrate data from different research areas, especially cognitive and psychopathologic indicators. Addresses implications of this theoretical approach. (Author/CR)
Islamic Theoretical Intertemporal Model of the Current Account
Hassan Belkacem Ghassan
2016-06-01
Full Text Available This paper aims to develop an Islamic intertemporal model of the current account based on the prevailing theoretical and empirical literature of PVMCA (Obstfeld and Rogoff, 1996, Cerrato et al., 2014. The proposed model is based on the budget constraint of the present and future consumption, which depends on the obligatory Zakat from the income and assets, the return rate on the owned assets, the inheritance linking previous to subsequent generation. Using logarithmic utility function, featured by a unitary elasticity of intertemporal substitution and a unitary coefficient of relative risk aversion, we show through Euler equation of consumption that there is an inverse relationship between consumption growth from the last age to the first one and the Zakat rate on assets. The outcomes of this result are that the Zakat on assets disciplines the consumer to have more rationality in consumption, and allows additional marginal assets for future generations. By assuming a unitary subjective discount rate, we indicate that the more the return rate on assets is high, the more the consumption growth between today and tomorrow will be fast. Through the budget constraint, if Zakat rate on the Zakatable assets is greater than Zakat rate on income, this leads to a relative expansion in private consumption of the wealthy group. Besides, we point out that an increase in return rate on assets, can drive to increasing or decreasing current consumption, because the substitution and income effects work in opposite ways.
A theoretical model for the Lorentz force particle analyzer
Moreau, René; Tao, Zhen; Wang, Xiaodong
2016-07-01
In a previous paper [X. Wang et al., J. Appl. Phys. 120, 014903 (2016)], several experimental devices have been presented, which demonstrate the efficiency of electromagnetic techniques for detecting and sizing electrically insulating particles entrained in the flow of a molten metal. In each case, a non-uniform magnetic field is applied across the flow of the electrically conducting liquid, thereby generating a braking Lorentz force on this moving medium and a reaction force on the magnet, which tends to be entrained in the flow direction. The purpose of this letter is to derive scaling laws for this Lorentz force from an elementary theoretical model. For simplicity, as in the experiments, the flowing liquid is modeled as a solid body moving with a uniform velocity U. The eddy currents in the moving domain are derived from the classic induction equation and Ohm's law, and expressions for the Lorentz force density j ×B and for its integral over the entire moving domain follow. The insulating particles that are eventually present and entrained with this body are then treated as small disturbances in a classic perturbation analysis, thereby leading to scaling laws for the pulses they generate in the Lorentz force. The purpose of this letter is both to illustrate the eddy currents without and with insulating particles in the electrically conducting liquid and to derive a key relation between the pulses in the Lorentz force and the main parameters (particle volume and dimensions of the region subjected to the magnetic field).
Information-theoretic model selection applied to supernovae data
Biesiada, M
2007-01-01
There are several different theoretical ideas invoked to explain the dark energy with relatively little guidance of which one of them might be right. Therefore the emphasis of ongoing and forthcoming research in this field shifts from estimating specific parameters of cosmological model to the model selection. In this paper we apply information-theoretic model selection approach based on Akaike criterion as an estimator of Kullback-Leibler entropy. In particular, we present the proper way of ranking the competing models based on Akaike weights (in Bayesian language - posterior probabilities of the models). Out of many particular models of dark energy we focus on four: quintessence, quintessence with time varying equation of state, brane-world and generalized Chaplygin gas model and test them on Riess' Gold sample. As a result we obtain that the best model - in terms of Akaike Criterion - is the quintessence model. The odds suggest that although there exist differences in the support given to specific scenario...
Theoretical Model Calculation for d + 8Li Reaction
HAN Yin-Lu; GUO Hai-Rui; ZHANG Yue; ZHANG Jing-Shang
2008-01-01
Based on the theoretical models for light nuclei, the calculations of reaction cross sections and the angular distributions for d+8Li reaction are performed. Since all of the particle emissions are from the compound nucleus to the discrete levels, the angular momentum coupling effect in pre-equilibrium mechanism is taken into account. The three-body break-up process and the recoil effect are involved. The theoretical calculated results are compared to existing experimental data.
Theoretical Model of Transformation Superlastic Diffusion Bonding for Eutectoid Steel
无
2002-01-01
Based on current theories of diffusion and creep cavity closure at high temperature, a theoretical analysis of phase transformation diffusion bonding for T8/T8 eutectoid steel is carried out. The diffusion bonding is mainly described as two-stage process: Ⅰ The interfacial cavity with shape change from diamond to cylinder.Ⅱ The radius of the cylindrical cavity are reduced and eliminated gradually. A new theoretical model is established for the process of transformation superplastic diffusion bonding (TSDB) ...
Modelling theoretical uncertainties in phenomenological analyses for particle physics
Charles, Jérôme; Niess, Valentin; Silva, Luiz Vale
2016-01-01
The determination of the fundamental parameters of the Standard Model (and its extensions) is often limited by the presence of statistical and theoretical uncertainties. We present several models for the latter uncertainties (random, nuisance, external) in the frequentist framework, and we derive the corresponding $p$-values. In the case of the nuisance approach where theoretical uncertainties are modeled as biases, we highlight the important, but arbitrary, issue of the range of variation chosen for the bias parameters. We introduce the concept of adaptive $p$-value, which is obtained by adjusting the range of variation for the bias according to the significance considered, and which allows us to tackle metrology and exclusion tests with a single and well-defined unified tool, which exhibits interesting frequentist properties. We discuss how the determination of fundamental parameters is impacted by the model chosen for theoretical uncertainties, illustrating several issues with examples from quark flavour p...
Modeling theoretical uncertainties in phenomenological analyses for particle physics
Charles, Jerome [CNRS, Aix-Marseille Univ, Universite de Toulon, CPT UMR 7332, Marseille Cedex 9 (France); Descotes-Genon, Sebastien [CNRS, Univ. Paris-Sud, Universite Paris-Saclay, Laboratoire de Physique Theorique (UMR 8627), Orsay Cedex (France); Niess, Valentin [CNRS/IN2P3, UMR 6533, Laboratoire de Physique Corpusculaire, Aubiere Cedex (France); Silva, Luiz Vale [CNRS, Univ. Paris-Sud, Universite Paris-Saclay, Laboratoire de Physique Theorique (UMR 8627), Orsay Cedex (France); Univ. Paris-Sud, CNRS/IN2P3, Universite Paris-Saclay, Groupe de Physique Theorique, Institut de Physique Nucleaire, Orsay Cedex (France); J. Stefan Institute, Jamova 39, P. O. Box 3000, Ljubljana (Slovenia)
2017-04-15
The determination of the fundamental parameters of the Standard Model (and its extensions) is often limited by the presence of statistical and theoretical uncertainties. We present several models for the latter uncertainties (random, nuisance, external) in the frequentist framework, and we derive the corresponding p values. In the case of the nuisance approach where theoretical uncertainties are modeled as biases, we highlight the important, but arbitrary, issue of the range of variation chosen for the bias parameters. We introduce the concept of adaptive p value, which is obtained by adjusting the range of variation for the bias according to the significance considered, and which allows us to tackle metrology and exclusion tests with a single and well-defined unified tool, which exhibits interesting frequentist properties. We discuss how the determination of fundamental parameters is impacted by the model chosen for theoretical uncertainties, illustrating several issues with examples from quark flavor physics. (orig.)
Hypermedia as an experiential learning tool: a theoretical model
Jose Miguel Baptista Nunes
1996-01-01
Full Text Available The process of methodical design and development is of extreme importance in the production of educational software. However, this process will only be effective, if it is based on a theoretical model that explicitly defines what educational approach is being used and how specific features of the technology can best support it. This paper proposes a theoretical model of how hypermedia can be used as an experiential learning tool. The development of the model was based on a experiential learning approach and simultaneously aims at minimising the inherent problems of hypermedia as the underlying support technology.
Category-theoretic models of linear Abadi & Plotkin Logic
Birkedal, Lars; Møgelberg, Rasmus Ejlers; Lerchedahl Petersen, Rasmus
2008-01-01
This paper presents a sound and complete category-theoretic notion of models for Linear Abadi & Plotkin Logic [Birkedal et al., 2006], a logic suitable for reasoning about parametricity in combination with recursion. A subclass of these called parametric LAPL structures can be seen as an axiomati......This paper presents a sound and complete category-theoretic notion of models for Linear Abadi & Plotkin Logic [Birkedal et al., 2006], a logic suitable for reasoning about parametricity in combination with recursion. A subclass of these called parametric LAPL structures can be seen...... as an axiomatization of domain theoretic models of parametric polymorphism, and we show how to solve general (nested) recursive domain equations in these. parametric LAPL structures constitute a general notion of model of parametricity in a setting with recursion. In future papers we will demonstrate this by showing...... how many different models of parametricity and recursion give rise to parametric LAPL structures, including Simpson and Rosolini’s set theoretic models [Rosolini and Simpson, 2004], a syntactic model based on Lily [Pitts, 2000, Bierman et al., 2000] and a model based on admissible pers over...
Theoretical bases of modeling decision-marketing solutions
Grigoruk Pavel Mikhaylovych
2012-01-01
The paper deals with issues related with theoretical aspects of modelling of marketing decision making process. According to system approach marketing decision making process is seen as a set of related subprocesses. Provided an opportunity to use the economic and mathematical modelling at each stage of the decision making process.
STRONG NORMALIZATION IN TYPE SYSTEMS - A MODEL THEORETICAL APPROACH
TERLOUW, J
1995-01-01
Tait's proof of strong normalization for the simply typed lambda-calculus is interpreted in a general model theoretical framework by means of the specification of a certain theory T and a certain model U of T. The argumentation is partly reduced to formal predicate logic by the application of
Theoretical modeling on the laser induced effect of liquid crystal optical phased beam steering
He, Xiaoxian; Wang, Xiangru; Wu, Liang; Tan, Qinggui; Li, Man; Shang, Jiyang; Wu, Shuanghong; Huang, Ziqiang
2017-01-01
Non-mechanical laser beam steering has been reported previously in liquid crystal array devices. To be one of the most promising candidates to be practical non-mechanical laser deflector, its laser induced effect still has few theoretical model. In this paper, we propose a theoretical model to analyze this laser induced effect of LC-OPA to evaluate the deterioration on phased beam steering. The model has three parts: laser induced thermal distribution; temperature dependence of material parameters and beam steering deterioration. After these three steps, the far field of laser beam is obtained to demonstrate the steering performance with the respect to the incident laser beam power and beam waist.
Fiberglass-reinforced glulam beams: mechanical properties and theoretical model
Juliano Fiorelli
2006-09-01
Full Text Available The glued-laminated lumber (glulam technique is an efficient process for making rational use of wood. Fiber-Reinforced Polymers (FRPs associated with glulam beams provide significant gains in terms of strength and stiffness, and also alter the mode of rupture of these structural elements. In this context, this paper presents a theoretical model for designing reinforced glulam beams. The model allows for the calculation of the bending moment, the hypothetical distribution of linear strains along the height of the beam, and considers the wood has a linear elastic fragile behavior in tension parallel to the fibers and bilinear in compression parallel to the fibers, initially elastic and subsequently inelastic, with a negative decline in the stress-strain diagram. The stiffness was calculated by the transformed section method. Twelve non-reinforced and fiberglass reinforced glulam beams were evaluated experimentally to validate the proposed theoretical model. The results obtained indicate good congruence between the experimental and theoretical values.
Modelling Opinion Dynamics: Theoretical analysis and continuous approximation
Pinasco, Juan Pablo; Balenzuela, Pablo
2016-01-01
Frequently we revise our first opinions after talking over with other individuals because we get convinced. Argumentation is a verbal and social process aimed at convincing. It includes conversation and persuasion. In this case, the agreement is reached because the new arguments are incorporated. In this paper we deal with a simple model of opinion formation with such persuasion dynamics, and we find the exact analytical solutions for both, long and short range interactions. A novel theoretical approach has been used in order to solve the master equations of the model with non-local kernels. Simulation results demonstrate an excellent agreement with results obtained by the theoretical estimation.
A New Theoretical Model of a Carbon Nanotube Strain Sensor
QIU Wei; KANG Yi-Lan; LEI Zhen-Kun; QIN Qing-Hua; LI Qiu
2009-01-01
Carbon nanotubes (CNTs) are potential strain sensors due to their excellent mechanical and spectral properties.A new theoretical model of a CNT strain sensor is obtained by applying the polarized Raman properties of CNTs,which calculates the synthetic contributions of Raman spectra from the CNTs in random directions.By using this theoretical model,the analytic relationship between planar strain components and the Raman shift increment of uniformly dispersed CNTs is obtained,which is applicable for accurately characterizing the strain in random directions on the surface of a measured microsystem.
Theoretical Relevance of Neuropsychological Data for Connectionist Modelling
Mauricio Iza
2011-05-01
Full Text Available The symbolic information-processing paradigm in cognitive psychology has met a growing challenge from neural network models over the past two decades. While neuropsychological
evidence has been of great utility to theories concerned with information processing, the real question is, whether the less rigid connectionist models provide valid, or enough, information
concerning complex cognitive structures. In this work, we will discuss the theoretical implications that neuropsychological data posits for modelling cognitive systems.
Passalia, Claudio; Alfano, Orlando M. [INTEC - Instituto de Desarrollo Tecnologico para la Industria Quimica, CONICET - UNL, Gueemes 3450, 3000 Santa Fe (Argentina); FICH - Departamento de Medio Ambiente, Facultad de Ingenieria y Ciencias Hidricas, Universidad Nacional del Litoral, Ciudad Universitaria, 3000 Santa Fe (Argentina); Brandi, Rodolfo J., E-mail: rbrandi@santafe-conicet.gov.ar [INTEC - Instituto de Desarrollo Tecnologico para la Industria Quimica, CONICET - UNL, Gueemes 3450, 3000 Santa Fe (Argentina); FICH - Departamento de Medio Ambiente, Facultad de Ingenieria y Ciencias Hidricas, Universidad Nacional del Litoral, Ciudad Universitaria, 3000 Santa Fe (Argentina)
2012-04-15
Highlights: Black-Right-Pointing-Pointer Indoor pollution control via photocatalytic reactors. Black-Right-Pointing-Pointer Scaling-up methodology based on previously determined mechanistic kinetics. Black-Right-Pointing-Pointer Radiation interchange model between catalytic walls using configuration factors. Black-Right-Pointing-Pointer Modeling and experimental validation of a complex geometry photocatalytic reactor. - Abstract: A methodology for modeling photocatalytic reactors for their application in indoor air pollution control is carried out. The methodology implies, firstly, the determination of intrinsic reaction kinetics for the removal of formaldehyde. This is achieved by means of a simple geometry, continuous reactor operating under kinetic control regime and steady state. The kinetic parameters were estimated from experimental data by means of a nonlinear optimization algorithm. The second step was the application of the obtained kinetic parameters to a very different photoreactor configuration. In this case, the reactor is a corrugated wall type using nanosize TiO{sub 2} as catalyst irradiated by UV lamps that provided a spatially uniform radiation field. The radiative transfer within the reactor was modeled through a superficial emission model for the lamps, the ray tracing method and the computation of view factors. The velocity and concentration fields were evaluated by means of a commercial CFD tool (Fluent 12) where the radiation model was introduced externally. The results of the model were compared experimentally in a corrugated wall, bench scale reactor constructed in the laboratory. The overall pollutant conversion showed good agreement between model predictions and experiments, with a root mean square error less than 4%.
Theoretical models in the development of advertising for food products
Bech-Larsen, Tino; Stacey, Julia
2005-01-01
Many advertising people believe that theoretical models hamper creativity and efficiency in the development of advertising messages. This need not be the case, if the theoretical models are sufficiently flexible and intelligible. On the contrary, a workable model that describes how...... the advertisement influences the target may serve as creative inspiration and as a common frame of reference for those involved in the development of advertisements. The means-end-chain model says that an advertisement is effective by connecting the product's attributes (means) and the target's personal values...... (ends). MAPP's experience with the model indicates that it is both flexible and intuitively accessible to practicians. In order to study this MAPP and the Danish Fruit Growers' Association asked an advertising agency to produce two campaign proposals with the purpose of getting young people to eat more...
Open forward and inverse problems in theoretical modeling of bone tissue adaptation.
Zadpoor, Amir Abbas
2013-11-01
Theoretical modeling of bone tissue adaptation started several decades ago. Many important problems have been addressed in this area of research during the last decades. However, many important questions remain unanswered. In this paper, an overview of open problems in theoretical modeling of bone tissue adaptation is presented. First, the principal elements of bone tissue adaptation models are defined and briefly reviewed. Based on these principal elements, four categories of open problems are identified. Two of these categories primarily include forward problems, while two others include inverse problems. In every one of the identified categories, important open problems are highlighted and their importance is discussed. It is shown that most of previous studies on the theoretical modeling of bone tissue adaptation have been focused on the problems of the first category and not much is done in three other categories. The paper tries to highlight these potentially important problems that have been so far largely overlooked and to inspire new avenues of research.
Xiaojin Li
2013-01-01
Full Text Available Previous studies have investigated both structural and functional brain networks via graph-theoretical methods. However, there is an important issue that has not been adequately discussed before: what is the optimal theoretical graph model for describing the structural networks of human brain? In this paper, we perform a comparative study to address this problem. Firstly, large-scale cortical regions of interest (ROIs are localized by recently developed and validated brain reference system named Dense Individualized Common Connectivity-based Cortical Landmarks (DICCCOL to address the limitations in the identification of the brain network ROIs in previous studies. Then, we construct structural brain networks based on diffusion tensor imaging (DTI data. Afterwards, the global and local graph properties of the constructed structural brain networks are measured using the state-of-the-art graph analysis algorithms and tools and are further compared with seven popular theoretical graph models. In addition, we compare the topological properties between two graph models, namely, stickiness-index-based model (STICKY and scale-free gene duplication model (SF-GD, that have higher similarity with the real structural brain networks in terms of global and local graph properties. Our experimental results suggest that among the seven theoretical graph models compared in this study, STICKY and SF-GD models have better performances in characterizing the structural human brain network.
Healing from Childhood Sexual Abuse: A Theoretical Model
Draucker, Claire Burke; Martsolf, Donna S.; Roller, Cynthia; Knapik, Gregory; Ross, Ratchneewan; Stidham, Andrea Warner
2011-01-01
Childhood sexual abuse is a prevalent social and health care problem. The processes by which individuals heal from childhood sexual abuse are not clearly understood. The purpose of this study was to develop a theoretical model to describe how adults heal from childhood sexual abuse. Community recruitment for an ongoing broader project on sexual…
THE THEORETICAL MODEL FOR PREDICTING CIRCULATION VELOCITY OF HYDRAULIC BRAKE
刘英林; 侯春生
1997-01-01
By rational hypothesis of fluid flow pattern, applied the law of conservation of energy and integrated the laboratory test results, finished the prediction by the theoretical model of circulation velocity of hydraulic brake which is important parameter. Thus provide the theoritical basis for hydraulic brake of belt conveyor whose research has just been started.
Organizational Learning and Product Design Management: Towards a Theoretical Model.
Chiva-Gomez, Ricardo; Camison-Zornoza, Cesar; Lapiedra-Alcami, Rafael
2003-01-01
Case studies of four Spanish ceramics companies were used to construct a theoretical model of 14 factors essential to organizational learning. One set of factors is related to the conceptual-analytical phase of the product design process and the other to the creative-technical phase. All factors contributed to efficient product design management…
THEORETICAL CHEMICAL ENGINEERING - Modeling and Simulation by Christo Boyadjiev
Simeon Oka
2010-01-01
Full Text Available Book Title: THEORETICAL CHEMICAL ENGINEERING - Modeling and Simulation Author(s: Christo Boyadjiev Institute of Chemical Engineering, Bulgarian Academy of Science, Sofia Publisher: Springer, 2010 ISBN: 978-3-642-10777-1 Review by: Prof. Simeon Oka, Ph. D., Scientific advisor - retired
THEORETICAL MODEL OF VIBRATING OBJECT TRANSMITTING NOISE TOWARDS EXTERNAL SOUND
姚志远
2002-01-01
On the basic theory of modal method, the coupling relation between the vibration of objects and external sound was analyzed, the theoretical model solving the vibration and noise was provided, the corresponding calculation formula was given. The calculating results show out that this calculation formula is correct.
Game-theoretic model of dispersed material drying process
Oleg, Malafeyev; Denis, Rylow; Irina, Zaitseva; Pavel, Zelenkovskii; Marina, Popova; Lydia, Novozhilova
2017-07-01
Continuous and discrete game-theoretic models of dispersed material drying process are formalized and studied in the paper. The existence of optimal drying strategies is shown through application of results from the theory of differential games and dynamic programming. These optimal strategies can be found numerically.
Organizational Resilience: The Theoretical Model and Research Implication
Xiao Lei
2017-01-01
Full Text Available Organizations are all subject to a diverse and ever changing and uncertain environment. Under this situation organizations should develop a capability which can resist the emergency and recover from the disruption. Base on lot of literature, the paper provides the main concept of organizational resilience; construct the primary theoretical model and some implications for management.
The Theoretical Foundation for Intercultural Business Communication: A Conceptual Model.
Varner, Iris I.
2000-01-01
Develops a theoretical framework for intercultural business communication which sets it apart from intercultural communication and international business. Presents a model that discusses the intercultural, business, and communication strategies that are part of intercultural business communication. Examines how past articles in the field fit into…
Healing from Childhood Sexual Abuse: A Theoretical Model
Draucker, Claire Burke; Martsolf, Donna S.; Roller, Cynthia; Knapik, Gregory; Ross, Ratchneewan; Stidham, Andrea Warner
2011-01-01
Childhood sexual abuse is a prevalent social and health care problem. The processes by which individuals heal from childhood sexual abuse are not clearly understood. The purpose of this study was to develop a theoretical model to describe how adults heal from childhood sexual abuse. Community recruitment for an ongoing broader project on sexual…
Model selection and inference a practical information-theoretic approach
Burnham, Kenneth P
1998-01-01
This book is unique in that it covers the philosophy of model-based data analysis and an omnibus strategy for the analysis of empirical data The book introduces information theoretic approaches and focuses critical attention on a priori modeling and the selection of a good approximating model that best represents the inference supported by the data Kullback-Leibler information represents a fundamental quantity in science and is Hirotugu Akaike's basis for model selection The maximized log-likelihood function can be bias-corrected to provide an estimate of expected, relative Kullback-Leibler information This leads to Akaike's Information Criterion (AIC) and various extensions and these are relatively simple and easy to use in practice, but little taught in statistics classes and far less understood in the applied sciences than should be the case The information theoretic approaches provide a unified and rigorous theory, an extension of likelihood theory, an important application of information theory, and are ...
A theoretical model for smoking prevention studies in preteen children.
McGahee, T W; Kemp, V; Tingen, M
2000-01-01
The age of the onset of smoking is on a continual decline, with the prime age of tobacco use initiation being 12-14 years. A weakness of the limited research conducted on smoking prevention programs designed for preteen children (ages 10-12) is a well-defined theoretical basis. A theoretical perspective is needed in order to make a meaningful transition from empirical analysis to application of knowledge. Bandura's Social Cognitive Theory (1977, 1986), the Theory of Reasoned Action (Ajzen & Fishbein, 1980), and other literature linking various concepts to smoking behaviors in preteens were used to develop a model that may be useful for smoking prevention studies in preteen children.
Theoretic computing model of combustion process of asphalt smoke
HUANG Rui; CHAI Li-yuan; HE De-wen; PENG Bing; WANG Yun-yan
2005-01-01
Based on the data and methods provided by research literature, dispersing mathematical model of combustion process of asphalt smoke is set by theoretic analysis. Through computer programming, the dynamic combustion process of asphalt smoke is calculated to simulate an experimental model. The computing result shows that the temperature and the concentration of asphalt smoke influence its burning temperature in approximatively linear manner. The consumed quantity of fuel to ignite the asphalt smoke needs to be measured from the two factors.
Critical review of problem solving processes traditional theoretical models
Botía Sanabria, María Lucero; Universidad Antonio Nariño, Bogotá, Colombia; Orozco Pulido, Luis Humberto; Universidad Antonio Nariño, Bogotá, Colombia
2015-01-01
This paper presents a brief analysis of most known problem solving theoretical models realized using epistemological categories such as observer position, object of study, methods and procedures, and descriptive or explicative scope. The review showed linear and cyclical models, the need to recognize method's limitations to generalizing, the relevance of expliciting observer position, and a diffuse delimitation of the object problem solving as a cognitive process. An integrative and molar the...
A Modified Theoretical Model of Intrinsic Hardness of Crystalline Solids
Fu-Zhi Dai; Yanchun Zhou
2016-01-01
Super-hard materials have been extensively investigated due to their practical importance in numerous industrial applications. To stimulate the design and exploration of new super-hard materials, microscopic models that elucidate the fundamental factors controlling hardness are desirable. The present work modified the theoretical model of intrinsic hardness proposed by Gao. In the modification, we emphasize the critical role of appropriately decomposing a crystal to pseudo-binary crystals, wh...
Examination of a Theoretical Model of Streaming Potential Coupling Coefficient
D. T. Luong
2014-01-01
Full Text Available Seismoelectric effects and streaming potentials play an important role in geophysical applications. The key parameter for those phenomena is the streaming potential coupling coefficient, which is, for example, dependent on the zeta potential of the interface of the porous rocks. Comparison of an existing theoretical model to experimental data sets from available published data for streaming potentials has been performed. However, the existing experimental data sets are based on samples with dissimilar fluid conductivity, pH of pore fluid, temperature, and sample compositions. All those dissimilarities may cause the observed deviations. To critically assess the models, we have carried out streaming potential measurement as a function of electrolyte concentration and temperature for a set of well-defined consolidated samples. The results show that the existing theoretical model is not in good agreement with the experimental observations when varying the electrolyte concentration, especially at low electrolyte concentration. However, if we use a modified model in which the zeta potential is considered to be constant over the electrolyte concentration, the model fits the experimental data well in a whole range of concentration. Also, for temperature dependence, the comparison shows that the theoretical model is not fully adequate to describe the experimental data but does describe correctly the increasing trend of the coupling coefficient as function of temperature.
Anwar, T.; Kravchinsky, V. A.; Zhang, R.
2015-12-01
The Chinese Loess Plateau contains red clay sequence which has continuous alternation of sedimentary cycles with recurrent paleoclimatic fluctuations. Absence of abundant fossils and inability of radiometric dating method made magnetostratigraphy a leading method to build age model for the red clay. Here magnetostratigraphic age model in red clay sequence is tested using cyclostratigraphy as orbital parameters of Earth are known. Milankovitch periodicities recorded in magnetic susceptibility and grain size in the Shilou red clay section are investigated and previously found age of 11 Ma for this section is re-evaluated. Magnetostratigraphy dating based on only visual correlation could potentially lead to erroneous age model. In this study the correlation is executed through the iteration procedure until it is supported by cyclostratigraphy; i.e. Milankovitch cycles are resolved in the best possible manner. Our new approach provides an age of 5.2 Ma for the Shilou profile. Wavelet analysis reveals that a 400 kyr eccentricity cycle is well preserved and the existence of a 100 kyr eccentricity in the red clay sequence on the eastern Chinese Loess Plateau suggests that eccentricity plays a vital role in Pliocene climate evolution. Paleomonsoon evolution is reconstructed and divided into three intervals (5.2-4.5 Ma, 4.5-3.6 Ma and 3.6-2.58 Ma). The earliest stage indicates that summer and winter monsoon cycles may rapidly alter, whereas the middle stage reflects an intensification of winter monsoon and aridification in Asia, and the youngest stage is characterized by relatively intensified summer monsoon. This study demonstrates that cyclostratigraphy can greatly assist magnetostratigraphy in dating the red clay sequences, and implies that many published age models for the red clay sequences should likely be re-assessed where possible. An evaluation of the monsoon system and climate change in eastern Asia might prominently benefit from this approach.
Lammi, Matthew R; Ghonim, Mohamed A; Pyakurel, Kusma; Naura, Amarjit S; Ibba, Salome V; Davis, Christian J; Okpechi, Samuel C; Happel, Kyle I; deBoisblanc, Bennett P; Shellito, Judd; Boulares, A Hamid
2016-04-01
Pulmonary endothelial prostacyclin appears to be involved in the pathogenesis of chronic obstructive pulmonary disease (COPD). The effect of treatment with a prostacyclin analog in animal models of previously established COPD is unknown. We evaluated the short- and long-term effect of iloprost on inflammation and airway hyperresponsiveness (AHR) in a murine model of COPD. Nineteen mice were exposed to LPS/elastase, followed by either three doses of intranasal iloprost or saline. In the long-term treatment experiment, 18 mice were exposed to LPS/elastase and then received 6 wk of iloprost or were left untreated as controls. In the short-term experiment, iloprost did not change AHR but significantly reduced serum IL-5 and IFN-γ. Long-term treatment with iloprost for both 2 and 6 wk significantly improved AHR. After 6 wk of iloprost, there was a reduction in bronchoalveolar lavage (BALF) neutrophils, serum IL-1β (30.0 ± 9.2 vs. 64.8 ± 7.4 pg/ml, P = 0.045), IL-2 (36.5 ± 10.6 vs. 83.8 ± 0.4 pg/ml, P = 0.01), IL-10 (75.7 ± 9.3 vs. 96.5 ± 3.5 pg/ml, P = 0.02), and nitrite (15.1 ± 5.4 vs. 30.5 ± 10.7 μmol, P = 0.01). Smooth muscle actin (SMA) in the lung homogenate was also significantly reduced after iloprost treatment (P = 0.02), and SMA thickness was reduced in the small and medium blood vessels after iloprost (P iloprost significantly reduced systemic inflammation in an LPS/elastase COPD model. Long-term iloprost treatment also reduced AHR, serum nitrite, SMA, and BALF neutrophilia. These data encourage future investigations of prostanoid therapy as a novel treatment for COPD patients. Copyright © 2016 the American Physiological Society.
Lind, M. [Oersted - DTU, Kgs. Lyngby (Denmark)
2005-10-01
Multilevel Flow Modeling (MFM) has proven to be an effective modeling tool for reasoning about plant failure and control strategies and is currently exploited for operator support in diagnosis and on-line alarm analysis. Previous MFM research was focussed on representing goals and functions of process plants which generate, transform and distribute mass and energy. However, only a limited consideration has been given to the problems of modeling the control systems. Control functions are indispensable for operating any industrial plant. But modeling of control system functions has proven to be a more challenging problem than modeling functions of energy and mass processes. The problems were discussed by Lind and tentative solutions has been proposed but have not been investigated in depth until recently, partly due to the lack of an appropriate theoretical foundation. The purposes of the present report are to show that such a theoretical foundation for modeling goals and functions of control systems can be built from concepts and theories of action developed by Von Wright and to show how the theoretical foundation can be used to extend MFM with concepts for modeling control systems. The theoretical foundations has been presented in detail elsewhere by the present author without the particular focus on modeling control actions and MFM adopted here. (au)
Aldiss, Don; Haslam, Richard
2013-04-01
In parts of London, faulting introduces lateral heterogeneity to the local ground conditions, especially where construction works intercept the Palaeogene Lambeth Group. This brings difficulties to the compilation of a ground model that is fully consistent with the ground investigation data, and so to the design and construction of engineering works. However, because bedrock in the London area is rather uniform at outcrop, and is widely covered by Quaternary deposits, few faults are shown on the geological maps of the area. This paper discusses a successful resolution of this problem at a site in east central London, where tunnels for a new underground railway station are planned. A 3D geological model was used to provide an understanding of the local geological structure, in faulted Lambeth Group strata, that had not been possible by other commonly-used methods. This model includes seven previously unrecognised faults, with downthrows ranging from about 1 m to about 12 m. The model was constructed in the GSI3D geological modelling software using about 145 borehole records, including many legacy records, in an area of 850 m by 500 m. The basis of a GSI3D 3D geological model is a network of 2D cross-sections drawn by a geologist, generally connecting borehole positions (where the borehole records define the level of the geological units that are present), and outcrop and subcrop lines for those units (where shown by a geological map). When the lines tracing the base of each geological unit within the intersecting cross-sections are complete and mutually consistent, the software is used to generate TIN surfaces between those lines, so creating a 3D geological model. Even where a geological model is constructed as if no faults were present, changes in apparent dip between two data points within a single cross-section can indicate that a fault is present in that segment of the cross-section. If displacements of similar size with the same polarity are found in a series
Multiscale modeling of complex materials phenomenological, theoretical and computational aspects
Trovalusci, Patrizia
2014-01-01
The papers in this volume deal with materials science, theoretical mechanics and experimental and computational techniques at multiple scales, providing a sound base and a framework for many applications which are hitherto treated in a phenomenological sense. The basic principles are formulated of multiscale modeling strategies towards modern complex multiphase materials subjected to various types of mechanical, thermal loadings and environmental effects. The focus is on problems where mechanics is highly coupled with other concurrent physical phenomena. Attention is also focused on the historical origins of multiscale modeling and foundations of continuum mechanics currently adopted to model non-classical continua with substructure, for which internal length scales play a crucial role.
Modelling the Noise-Robustness of Infants' Word Representations: The Impact of Previous Experience.
Christina Bergmann
Full Text Available During language acquisition, infants frequently encounter ambient noise. We present a computational model to address whether specific acoustic processing abilities are necessary to detect known words in moderate noise--an ability attested experimentally in infants. The model implements a general purpose speech encoding and word detection procedure. Importantly, the model contains no dedicated processes for removing or cancelling out ambient noise, and it can replicate the patterns of results obtained in several infant experiments. In addition to noise, we also addressed the role of previous experience with particular target words: does the frequency of a word matter, and does it play a role whether that word has been spoken by one or multiple speakers? The simulation results show that both factors affect noise robustness. We also investigated how robust word detection is to changes in speaker identity by comparing words spoken by known versus unknown speakers during the simulated test. This factor interacted with both noise level and past experience, showing that an increase in exposure is only helpful when a familiar speaker provides the test material. Added variability proved helpful only when encountering an unknown speaker. Finally, we addressed whether infants need to recognise specific words, or whether a more parsimonious explanation of infant behaviour, which we refer to as matching, is sufficient. Recognition involves a focus of attention on a specific target word, while matching only requires finding the best correspondence of acoustic input to a known pattern in the memory. Attending to a specific target word proves to be more noise robust, but a general word matching procedure can be sufficient to simulate experimental data stemming from young infants. A change from acoustic matching to targeted recognition provides an explanation of the improvements observed in infants around their first birthday. In summary, we present a
A General Theoretical Model of Enthalpy-EntropyCompensation
LIU，Lei; GUO, Qing-Xiang
2001-01-01
Enthalpy-entropy compensation remains a mystery in chemistry and biophysics.recent study suggested that the solventreorganization might constitute the physical orihin of the compensation, which was unforumstely not wisely applicable because compensation was also observeserved in solid phade reactions.In this study,a general theoretical model based upon strictmathematical deduction was presented,which indicated thatthe redistribution of the distinguishable subspecies might bethe physical origin of the enthalpy-intropy compensations in solvation and surface adsorption weue discussed.
A theoretical retention model for unsaturated uniform and graded soils
Monnet Jacques
2016-01-01
Full Text Available Modelling the relation between the degree of saturation and the suction (ie retention curve is an important challenge for geotechnical engineering. It has a huge influence on the behavior of large soil constructions as levees, embankments, road earthworks. We present here a theoretical model of retention curve which considers physical relations of unsaturated soils. With this approach, there is no need to assume particular shapes of the retention curves, which are a consequence of the physical assumptions. The present study is focused on a theoretical model based on elastic spherical particle arrangement. As a first step a uniform model is presented with a single diameter of soil particle. A second step extends the use of the model to graded soils. The model uses only 5 physical parameters. It is compared with the experimental retention curve of two different samples of glass uniform particles and two different graded soils, a graded glass sample and the Livet-Gavet loam. It shows its ability to model the experimental curves and a better agreement than the former theory of Brooks and Corey (1966. This current publication is funded by the French National Project «Terredurable» (ANR 2011,.
A Theoretical Framework for Physics Education Research: Modeling Student Thinking
Redish, E F
2004-01-01
Education is a goal-oriented field. But if we want to treat education scientifically so we can accumulate, evaluate, and refine what we learn, then we must develop a theoretical framework that is strongly rooted in objective observations and through which different theoretical models of student thinking can be compared. Much that is known in the behavioral sciences is robust and observationally based. In this paper, I draw from a variety of fields ranging from neuroscience to sociolinguistics to propose an over-arching theoretical framework that allows us to both make sense of what we see in the classroom and to compare a variety of specific theoretical approaches. My synthesis is organized around an analysis of the individual's cognition and how it interacts with the environment. This leads to a two level system, a knowledge-structure level where associational patterns dominate, and a control-structure level where one can describe expectations and epistemology. For each level, I sketch some plausible startin...
Application of a theoretical model to evaluate COPD disease management.
Lemmens, Karin M M; Nieboer, Anna P; Rutten-Van Mölken, Maureen P M H; van Schayck, Constant P; Asin, Javier D; Dirven, Jos A M; Huijsman, Robbert
2010-03-26
Disease management programmes are heterogeneous in nature and often lack a theoretical basis. An evaluation model has been developed in which theoretically driven inquiries link disease management interventions to outcomes. The aim of this study is to methodically evaluate the impact of a disease management programme for patients with chronic obstructive pulmonary disease (COPD) on process, intermediate and final outcomes of care in a general practice setting. A quasi-experimental research was performed with 12-months follow-up of 189 COPD patients in primary care in the Netherlands. The programme included patient education, protocolised assessment and treatment of COPD, structural follow-up and coordination by practice nurses at 3, 6 and 12 months. Data on intermediate outcomes (knowledge, psychosocial mediators, self-efficacy and behaviour) and final outcomes (dyspnoea, quality of life, measured by the CRQ and CCQ, and patient experiences) were obtained from questionnaires and electronic registries. Implementation of the programme was associated with significant improvements in dyspnoea (p model showed associations between significantly improved intermediate outcomes and improvements in quality of life and dyspnoea. The application of a theory-driven model enhances the design and evaluation of disease management programmes aimed at improving health outcomes. This study supports the notion that a theoretical approach strengthens the evaluation designs of complex interventions. Moreover, it provides prudent evidence that the implementation of COPD disease management programmes can positively influence outcomes of care.
Cusack, Lynette; Smith, Morgan; Hegney, Desley; Rees, Clare S.; Breen, Lauren J.; Witt, Regina R.; Rogers, Cath; Williams, Allison; Cross, Wendy; Cheung, Kin
2016-01-01
Building nurses' resilience to complex and stressful practice environments is necessary to keep skilled nurses in the workplace and ensuring safe patient care. A unified theoretical framework titled Health Services Workplace Environmental Resilience Model (HSWERM), is presented to explain the environmental factors in the workplace that promote nurses' resilience. The framework builds on a previously-published theoretical model of individual resilience, which identified the key constructs of psychological resilience as self-efficacy, coping and mindfulness, but did not examine environmental factors in the workplace that promote nurses' resilience. This unified theoretical framework was developed using a literary synthesis drawing on data from international studies and literature reviews on the nursing workforce in hospitals. The most frequent workplace environmental factors were identified, extracted and clustered in alignment with key constructs for psychological resilience. Six major organizational concepts emerged that related to a positive resilience-building workplace and formed the foundation of the theoretical model. Three concepts related to nursing staff support (professional, practice, personal) and three related to nursing staff development (professional, practice, personal) within the workplace environment. The unified theoretical model incorporates these concepts within the workplace context, linking to the nurse, and then impacting on personal resilience and workplace outcomes, and its use has the potential to increase staff retention and quality of patient care. PMID:27242567
Cusack, Lynette; Smith, Morgan; Hegney, Desley; Rees, Clare S; Breen, Lauren J; Witt, Regina R; Rogers, Cath; Williams, Allison; Cross, Wendy; Cheung, Kin
2016-01-01
Building nurses' resilience to complex and stressful practice environments is necessary to keep skilled nurses in the workplace and ensuring safe patient care. A unified theoretical framework titled Health Services Workplace Environmental Resilience Model (HSWERM), is presented to explain the environmental factors in the workplace that promote nurses' resilience. The framework builds on a previously-published theoretical model of individual resilience, which identified the key constructs of psychological resilience as self-efficacy, coping and mindfulness, but did not examine environmental factors in the workplace that promote nurses' resilience. This unified theoretical framework was developed using a literary synthesis drawing on data from international studies and literature reviews on the nursing workforce in hospitals. The most frequent workplace environmental factors were identified, extracted and clustered in alignment with key constructs for psychological resilience. Six major organizational concepts emerged that related to a positive resilience-building workplace and formed the foundation of the theoretical model. Three concepts related to nursing staff support (professional, practice, personal) and three related to nursing staff development (professional, practice, personal) within the workplace environment. The unified theoretical model incorporates these concepts within the workplace context, linking to the nurse, and then impacting on personal resilience and workplace outcomes, and its use has the potential to increase staff retention and quality of patient care.
Theoretical results on the tandem junction solar cell based on its Ebers-Moll transistor model
Goradia, C.; Vaughn, J.; Baraona, C. R.
1980-01-01
A one-dimensional theoretical model of the tandem junction solar cell (TJC) with base resistivity greater than about 1 ohm-cm and under low level injection has been derived. This model extends a previously published conceptual model which treats the TJC as an npn transistor. The model gives theoretical expressions for each of the Ebers-Moll type currents of the illuminated TJC and allows for the calculation of the spectral response, I(sc), V(oc), FF and eta under variation of one or more of the geometrical and material parameters and 1MeV electron fluence. Results of computer calculations based on this model are presented and discussed. These results indicate that for space applications, both a high beginning of life efficiency, greater than 15% AM0, and a high radiation tolerance can be achieved only with thin (less than 50 microns) TJC's with high base resistivity (greater than 10 ohm-cm).
Information Theoretic Tools for Parameter Fitting in Coarse Grained Models
Kalligiannaki, Evangelia
2015-01-07
We study the application of information theoretic tools for model reduction in the case of systems driven by stochastic dynamics out of equilibrium. The model/dimension reduction is considered by proposing parametrized coarse grained dynamics and finding the optimal parameter set for which the relative entropy rate with respect to the atomistic dynamics is minimized. The minimization problem leads to a generalization of the force matching methods to non equilibrium systems. A multiplicative noise example reveals the importance of the diffusion coefficient in the optimization problem.
A theoretical model of multi-agent quantum computing
Mihelic, F. Matthew
2011-05-01
The best design for practical quantum computing is one that emulates the multi-agent quantum logic function of natural biological systems. Such systems are theorized to be based upon a quantum gate formed by a nucleic acid Szilard engine (NASE) that converts Shannon entropy of encountered molecules into useful work of nucleic acid geometric reconfiguration. This theoretical mechanism is logically and thermodynamically reversible in this special case because it is literally constructed out of the (nucleic acid) information necessary for its function, thereby allowing the nucleic acid Szilard engine to function reversibly because, since the information by which it functions exists on both sides of the theoretical mechanism simultaneously, there would be no build-up of information within the theoretical mechanism, and therefore no irreversible thermodynamic energy cost would be necessary to erase information inside the mechanism. This symmetry breaking Szilard engine function is associated with emission and/or absorption of entangled photons that can provide quantum synchronization of other nucleic acid segments within and between cells. In this manner nucleic acids can be considered as a natural model of topological quantum computing in which the nonabelian interaction of genes can be represented within quantum knot/braid theory as anyon crosses determined by entropic loss or gain that leads to changes in nucleic acid covalent bond angles. This naturally occurring biological form of topological quantum computing can serve as a model for workable man-made multi-agent quantum computing systems.
Application of a theoretical model to evaluate COPD disease management
Asin Javier D
2010-03-01
Full Text Available Abstract Background Disease management programmes are heterogeneous in nature and often lack a theoretical basis. An evaluation model has been developed in which theoretically driven inquiries link disease management interventions to outcomes. The aim of this study is to methodically evaluate the impact of a disease management programme for patients with chronic obstructive pulmonary disease (COPD on process, intermediate and final outcomes of care in a general practice setting. Methods A quasi-experimental research was performed with 12-months follow-up of 189 COPD patients in primary care in the Netherlands. The programme included patient education, protocolised assessment and treatment of COPD, structural follow-up and coordination by practice nurses at 3, 6 and 12 months. Data on intermediate outcomes (knowledge, psychosocial mediators, self-efficacy and behaviour and final outcomes (dyspnoea, quality of life, measured by the CRQ and CCQ, and patient experiences were obtained from questionnaires and electronic registries. Results Implementation of the programme was associated with significant improvements in dyspnoea (p Conclusions The application of a theory-driven model enhances the design and evaluation of disease management programmes aimed at improving health outcomes. This study supports the notion that a theoretical approach strengthens the evaluation designs of complex interventions. Moreover, it provides prudent evidence that the implementation of COPD disease management programmes can positively influence outcomes of care.
Polarisers in the focal domain: Theoretical model and experimental validation
Martínez-Herrero, Rosario; Maluenda, David; Juvells, Ignasi; Carnicer, Artur
2017-02-01
Polarisers are one of the most widely used devices in optical set-ups. They are commonly used with paraxial beams that propagate in the normal direction of the polariser plane. Nevertheless, the conventional projection character of these devices may change when the beam impinges a polariser with a certain angle of incidence. This effect is more noticeable if polarisers are used in optical systems with a high numerical aperture, because multiple angles of incidence have to be taken into account. Moreover, the non-transverse character of highly focused beams makes the problem more complex and strictly speaking, the Malus’ law does not apply. In this paper we develop a theoretical framework to explain how ideal polarisers affect the behavior of highly focused fields. In this model, the polarisers are considered as birefringent plates, and the vector behaviour of focused fields is described using the plane-wave angular spectrum approach. Experiments involving focused fields were conducted to verify the theoretical model and a satisfactory agreement between theoretical and experimental results was found.
Agha Mohammad Ali Kermani, Mehrdad; Fatemi Ardestani, Seyed Farshad; Aliahmadi, Alireza; Barzinpour, Farnaz
2017-01-01
Influence maximization deals with identification of the most influential nodes in a social network given an influence model. In this paper, a game theoretic framework is developed that models a competitive influence maximization problem. A novel competitive influence model is additionally proposed that incorporates user heterogeneity, message content, and network structure. The proposed game-theoretic model is solved using Nash Equilibrium in a real-world dataset. It is shown that none of the well-known strategies are stable and at least one player has the incentive to deviate from the proposed strategy. Moreover, violation of Nash equilibrium strategy by each player leads to their reduced payoff. Contrary to previous works, our results demonstrate that graph topology, as well as the nodes' sociability and initial tendency measures have an effect on the determination of the influential node in the network.
A Modified Theoretical Model of Intrinsic Hardness of Crystalline Solids
Dai, Fu-Zhi; Zhou, Yanchun
2016-01-01
Super-hard materials have been extensively investigated due to their practical importance in numerous industrial applications. To stimulate the design and exploration of new super-hard materials, microscopic models that elucidate the fundamental factors controlling hardness are desirable. The present work modified the theoretical model of intrinsic hardness proposed by Gao. In the modification, we emphasize the critical role of appropriately decomposing a crystal to pseudo-binary crystals, which should be carried out based on the valence electron population of each bond. After modification, the model becomes self-consistent and predicts well the hardness values of many crystals, including crystals composed of complex chemical bonds. The modified model provides fundamental insights into the nature of hardness, which can facilitate the quest for intrinsic super-hard materials. PMID:27604165
The creep experiment and theoretical model analysis of gascontaining coal
YIN Guang-zhi; ZHANG Dong-ming; WANG Wei-zhong
2007-01-01
A creep experiment of preformed molding coal under different confining pressures were carried out using self-developed 3-triaxial creep loading device for gas-containing coal, which loaded by Shimadzu AGI-250 kN electrical servo-controlled stiffness testing machine. Based on the experimental results, the variation trend of axial deformation under different stress states was studied, and creep failure characteristics of gascontaining coal under different confining pressures were analyzed. The experimental results were identified with seven-component nonlinear viscoelasto-plastic creep model (Hohai model), and the creep material parameters were obtained. The experimental result complies well with the theoretical value of this model. It indicates that creep constitutive relation of gas-containing coal can be expressed by nonlinear viscoelasto-plastic creep model correctly.
A Modified Theoretical Model of Intrinsic Hardness of Crystalline Solids
Dai, Fu-Zhi; Zhou, Yanchun
2016-09-01
Super-hard materials have been extensively investigated due to their practical importance in numerous industrial applications. To stimulate the design and exploration of new super-hard materials, microscopic models that elucidate the fundamental factors controlling hardness are desirable. The present work modified the theoretical model of intrinsic hardness proposed by Gao. In the modification, we emphasize the critical role of appropriately decomposing a crystal to pseudo-binary crystals, which should be carried out based on the valence electron population of each bond. After modification, the model becomes self-consistent and predicts well the hardness values of many crystals, including crystals composed of complex chemical bonds. The modified model provides fundamental insights into the nature of hardness, which can facilitate the quest for intrinsic super-hard materials.
A Modified Theoretical Model of Intrinsic Hardness of Crystalline Solids.
Dai, Fu-Zhi; Zhou, Yanchun
2016-09-08
Super-hard materials have been extensively investigated due to their practical importance in numerous industrial applications. To stimulate the design and exploration of new super-hard materials, microscopic models that elucidate the fundamental factors controlling hardness are desirable. The present work modified the theoretical model of intrinsic hardness proposed by Gao. In the modification, we emphasize the critical role of appropriately decomposing a crystal to pseudo-binary crystals, which should be carried out based on the valence electron population of each bond. After modification, the model becomes self-consistent and predicts well the hardness values of many crystals, including crystals composed of complex chemical bonds. The modified model provides fundamental insights into the nature of hardness, which can facilitate the quest for intrinsic super-hard materials.
A Game-Theoretic Model for Distributed Programming by Contract
Henriksen, Anders Starcke; Hvitved, Tom; Filinski, Andrzej
2009-01-01
We present an extension of the programming-by-contract (PBC) paradigm to a concurrent and distributed environment. Classical PBC is characterized by absolute conformance of code to its specification, assigning blame in case of failures, and a hierarchical, cooperative decomposition model – none...... of which extend naturally to a distributed environment with multiple administrative peers. We therefore propose a more nuanced contract model based on quantifiable performance of implementations; assuming responsibility for success; and a fundamentally adversarial model of system integration, where each...... component provider is optimizing its behavior locally, with respect to potentially conflicting demands. This model gives rise to a game-theoretic formulation of contract-governed process interactions that supports compositional reasoning about contract conformance....
Stability of theoretical model for catastrophic weather prediction
SHI Wei-hui; WANG Yue-peng
2007-01-01
Stability related to theoretical model for catastrophic weather prediction,which includes non-hydrostatic perfect elastic model and anelastic model, is discussed and analyzed in detail. It is proved that non-hydrostatic perfect elastic equations set is stable in the class of infinitely differentiable function. However, for the anelastic equations set, its continuity equation is changed in form because of the particular hypothesis for fluid, so "the matching consisting of both viscosity coefficient and incompressible assumption" appears, thereby the most important equations set of this class in practical prediction shows the same instability in topological property as Navier-Stokes equation,which should be avoided first in practical numerical prediction. In light of this, the referenced suggestions to amend the applied model are finally presented.
Comparing theoretical models of our galaxy with observations
Johnston K.V.
2012-02-01
Full Text Available With the advent of large scale observational surveys to map out the stars in our galaxy, there is a need for an efficient tool to compare theoretical models of our galaxy with observations. To this end, we describe here the code Galaxia, which uses efficient and fast algorithms for creating a synthetic survey of the Milky Way, and discuss its uses. Given one or more observational constraints like the color-magnitude bounds, a survey size and geometry, Galaxia returns a catalog of stars in accordance with a given theoretical model of the Milky Way. Both analytic and N-body models can be sampled by Galaxia. For N-body models, we present a scheme that disperses the stars spawned by an N-body particle, in such a way that the phase space density of the spawned stars is consistent with that of the N-body particles. The code is ideally suited to generating synthetic data sets that mimic near future wide area surveys such as GAIA, LSST and HERMES. In future, we plan to release the code publicly at http://galaxia.sourceforge.net. As an application of the code, we study the prospect of identifying structures in the stellar halo with future surveys that will have velocity information about the stars.
Theoretical consideration of a microcontinuum model of graphene
Gang Yang
2016-05-01
Full Text Available A microcontinuum model of graphene is proposed based on micromorphic theory, in which the planar Bravais cell of graphene crystal is taken as the basal element of finite size. Governing equations including the macro-displacements and the micro-deformations of the basal element are modified and derived in global coordinates. Since independent freedom degrees of the basal element are closely related to the modes of phonon dispersions, the secular equations in micromorphic form are obtained by substituting the assumed harmonic wave equations into the governing equations, and simplified further according to the properties of phonon dispersion relations of two-dimensional (2D crystals. Thus, the constitutive equations of the microcontinuum model are confirmed, in which the constitutive constants are determined by fitting the data of experimental and theoretical phonon dispersion relations in literature respectively. By employing the 2D microcontinuum model, we obtained sound velocities, Rayleigh velocity and elastic moduli of graphene, which show good agreements with available experimental or theoretical values, indicating that the current model would be another efficient and reliable methodology to study the mechanical behaviors of graphene.
Information-Theoretic Benchmarking of Land Surface Models
Nearing, Grey; Mocko, David; Kumar, Sujay; Peters-Lidard, Christa; Xia, Youlong
2016-04-01
Benchmarking is a type of model evaluation that compares model performance against a baseline metric that is derived, typically, from a different existing model. Statistical benchmarking was used to qualitatively show that land surface models do not fully utilize information in boundary conditions [1] several years before Gong et al [2] discovered the particular type of benchmark that makes it possible to *quantify* the amount of information lost by an incorrect or imperfect model structure. This theoretical development laid the foundation for a formal theory of model benchmarking [3]. We here extend that theory to separate uncertainty contributions from the three major components of dynamical systems models [4]: model structures, model parameters, and boundary conditions describe time-dependent details of each prediction scenario. The key to this new development is the use of large-sample [5] data sets that span multiple soil types, climates, and biomes, which allows us to segregate uncertainty due to parameters from the two other sources. The benefit of this approach for uncertainty quantification and segregation is that it does not rely on Bayesian priors (although it is strictly coherent with Bayes' theorem and with probability theory), and therefore the partitioning of uncertainty into different components is *not* dependent on any a priori assumptions. We apply this methodology to assess the information use efficiency of the four land surface models that comprise the North American Land Data Assimilation System (Noah, Mosaic, SAC-SMA, and VIC). Specifically, we looked at the ability of these models to estimate soil moisture and latent heat fluxes. We found that in the case of soil moisture, about 25% of net information loss was from boundary conditions, around 45% was from model parameters, and 30-40% was from the model structures. In the case of latent heat flux, boundary conditions contributed about 50% of net uncertainty, and model structures contributed
An information theoretic approach for combining neural network process models.
Sridhar, D V.; Bartlett, E B.; Seagrave, R C.
1999-07-01
Typically neural network modelers in chemical engineering focus on identifying and using a single, hopefully optimal, neural network model. Using a single optimal model implicitly assumes that one neural network model can extract all the information available in a given data set and that the other candidate models are redundant. In general, there is no assurance that any individual model has extracted all relevant information from the data set. Recently, Wolpert (Neural Networks, 5(2), 241 (1992)) proposed the idea of stacked generalization to combine multiple models. Sridhar, Seagrave and Barlett (AIChE J., 42, 2529 (1996)) implemented the stacked generalization for neural network models by integrating multiple neural networks into an architecture known as stacked neural networks (SNNs). SNNs consist of a combination of the candidate neural networks and were shown to provide improved modeling of chemical processes. However, in Sridhar's work SNNs were limited to using a linear combination of artificial neural networks. While a linear combination is simple and easy to use, it can utilize only those model outputs that have a high linear correlation to the output. Models that are useful in a nonlinear sense are wasted if a linear combination is used. In this work we propose an information theoretic stacking (ITS) algorithm for combining neural network models. The ITS algorithm identifies and combines useful models regardless of the nature of their relationship to the actual output. The power of the ITS algorithm is demonstrated through three examples including application to a dynamic process modeling problem. The results obtained demonstrate that the SNNs developed using the ITS algorithm can achieve highly improved performance as compared to selecting and using a single hopefully optimal network or using SNNs based on a linear combination of neural networks.
Theoretical Models and Operational Frameworks in Public Health Ethics
Petrini, Carlo
2010-01-01
The article is divided into three sections: (i) an overview of the main ethical models in public health (theoretical foundations); (ii) a summary of several published frameworks for public health ethics (practical frameworks); and (iii) a few general remarks. Rather than maintaining the superiority of one position over the others, the main aim of the article is to summarize the basic approaches proposed thus far concerning the development of public health ethics by describing and comparing the various ideas in the literature. With this in mind, an extensive list of references is provided. PMID:20195441
Theoretical Models and Operational Frameworks in Public Health Ethics
Carlo Petrini
2010-01-01
Full Text Available The article is divided into three sections: (i an overview of the main ethical models in public health (theoretical foundations; (ii a summary of several published frameworks for public health ethics (practical frameworks; and (iii a few general remarks. Rather than maintaining the superiority of one position over the others, the main aim of the article is to summarize the basic approaches proposed thus far concerning the development of public health ethics by describing and comparing the various ideas in the literature. With this in mind, an extensive list of references is provided.
Information Theoretic Authentication and Secrecy Codes in the Splitting Model
Huber, Michael
2011-01-01
In the splitting model, information theoretic authentication codes allow non-deterministic encoding, that is, several messages can be used to communicate a particular plaintext. Certain applications require that the aspect of secrecy should hold simultaneously. Ogata-Kurosawa-Stinson-Saido (2004) have constructed optimal splitting authentication codes achieving perfect secrecy for the special case when the number of keys equals the number of messages. In this paper, we establish a construction method for optimal splitting authentication codes with perfect secrecy in the more general case when the number of keys may differ from the number of messages. To the best knowledge, this is the first result of this type.
A survey of game-theoretic models of cooperative advertising
Jørgensen, Steffen; Zaccour, G.
2014-01-01
The paper surveys the literature on cooperative advertising in marketing channels (supply chains) using game theoretic methods. During the last decade, in particular, this literature has expanded considerably and has studied static as well as dynamic settings. The survey is divided into two main...... environments. We also find that the work on static models is quite homogeneous, in the sense that most papers employ the same basic consumer demand specification and address the same situations of vertical integration and noncooperative games with simultaneous or sequential actions. The work on dynamic...
Experimental and theoretical models of human cultural evolution.
Kempe, Marius; Mesoudi, Alex
2014-05-01
The modern field of cultural evolution is now over 30 years old, and an extensive body of theory and data has been amassed. This article reviews models of cultural evolution, both experimental and theoretical, and surveys what they can tell us about cultural evolutionary processes. The models are grouped according to which of four broad questions they address: (1) How are cultural traits changed during transmission? (2) How and why do cultural traits accumulate over time? (3) What social learning biases do people use? and (4) What are the population-level consequences of different social learning biases? We conclude by highlighting gaps in the literature and promising future research directions, including the further integration of theoretical models and experimental data, the identification of the factors underlying cumulative cultural evolution, and the explanation of individual and cultural variation in social learning biases. For further resources related to this article, please visit the WIREs website. The authors have declared no conflicts of interest for this article. © 2014 John Wiley & Sons, Ltd.
Theoretical modeling techniques and their impact on tumor immunology.
Woelke, Anna Lena; Murgueitio, Manuela S; Preissner, Robert
2010-01-01
Currently, cancer is one of the leading causes of death in industrial nations. While conventional cancer treatment usually results in the patient suffering from severe side effects, immunotherapy is a promising alternative. Nevertheless, some questions remain unanswered with regard to using immunotherapy to treat cancer hindering it from being widely established. To help rectify this deficit in knowledge, experimental data, accumulated from a huge number of different studies, can be integrated into theoretical models of the tumor-immune system interaction. Many complex mechanisms in immunology and oncology cannot be measured in experiments, but can be analyzed by mathematical simulations. Using theoretical modeling techniques, general principles of tumor-immune system interactions can be explored and clinical treatment schedules optimized to lower both tumor burden and side effects. In this paper, we aim to explain the main mathematical and computational modeling techniques used in tumor immunology to experimental researchers and clinicians. In addition, we review relevant published work and provide an overview of its impact to the field.
Theoretical models for coronary vascular biomechanics: Progress & challenges
Waters, Sarah L.; Alastruey, Jordi; Beard, Daniel A.; Bovendeerd, Peter H.M.; Davies, Peter F.; Jayaraman, Girija; Jensen, Oliver E.; Lee, Jack; Parker, Kim H.; Popel, Aleksander S.; Secomb, Timothy W.; Siebes, Maria; Sherwin, Spencer J.; Shipley, Rebecca J.; Smith, Nicolas P.; van de Vosse, Frans N.
2013-01-01
A key aim of the cardiac Physiome Project is to develop theoretical models to simulate the functional behaviour of the heart under physiological and pathophysiological conditions. Heart function is critically dependent on the delivery of an adequate blood supply to the myocardium via the coronary vasculature. Key to this critical function of the coronary vasculature is system dynamics that emerge via the interactions of the numerous constituent components at a range of spatial and temporal scales. Here, we focus on several components for which theoretical approaches can be applied, including vascular structure and mechanics, blood flow and mass transport, flow regulation, angiogenesis and vascular remodelling, and vascular cellular mechanics. For each component, we summarise the current state of the art in model development, and discuss areas requiring further research. We highlight the major challenges associated with integrating the component models to develop a computational tool that can ultimately be used to simulate the responses of the coronary vascular system to changing demands and to diseases and therapies. PMID:21040741
Self-Assembled Magnetic Surface Swimmers: Theoretical Model
Aranson, Igor; Belkin, Maxim; Snezhko, Alexey
2009-03-01
The mechanisms of self-propulsion of living microorganisms are a fascinating phenomenon attracting enormous attention in the physics community. A new type of self-assembled micro-swimmers, magnetic snakes, is an excellent tool to model locomotion in a simple table-top experiment. The snakes self-assemble from a dispersion of magnetic microparticles suspended on the liquid-air interface and subjected to an alternating magnetic field. Formation and dynamics of these swimmers are captured in the framework of theoretical model coupling paradigm equation for the amplitude of surface waves, conservation law for the density of particles, and the Navier-Stokes equation for hydrodynamic flows. The results of continuum modeling are supported by hybrid molecular dynamics simulations of magnetic particles floating on the surface of fluid.
Naturalness of unknown physics: Theoretical models and experimental signatures
Kilic, Can
In the last few decades collider experiments have not only spectacularly confirmed the predictions of the Standard Model but also have not revealed any direct evidence for new physics beyond the SM, which has led theorists to devise numerous models where the new physics couples weakly to the SM or is simply beyond the reach of past experiments. While phenomenologically viable, many such models appear finely tuned, even contrived. This work illustrates three attempts at coming up with explanations to fine-tunings we observe in the world around us, such as the gauge hierarchy problem or the cosmological constant problem, emphasizing both the theoretical aspects of model building as well as possible experimental signatures. First we investigate the "Little Higgs" mechanism and work on a specifical model, the "Minimal Moose" to highlight its impact on precision observables in the SM, and illustrate that it does not require implausible fine-tuning. Next we build a supersymmetric model, the "Fat Higgs", with an extended gauge structure which becomes confining. This model, aside from naturally preserving the unification of the SM gauge couplings at high energies, also makes it possible to evade the bounds on the lightest Higgs boson mass which are quite restrictive in minimal SUSY scenarios. Lastly we take a look at a possible resolution of the cosmological constant problem through the mechanism of "Ghost Condensation" and dwell on astrophysical observables from the Lorentz Violating sector in this model. We use current experimental data to constrain the coupling of this sector to the SM.
Accuracy Analysis of a Box-wing Theoretical SRP Model
Wang, Xiaoya; Hu, Xiaogong; Zhao, Qunhe; Guo, Rui
2016-07-01
For Beidou satellite navigation system (BDS) a high accuracy SRP model is necessary for high precise applications especially with Global BDS establishment in future. The BDS accuracy for broadcast ephemeris need be improved. So, a box-wing theoretical SRP model with fine structure and adding conical shadow factor of earth and moon were established. We verified this SRP model by the GPS Block IIF satellites. The calculation was done with the data of PRN 1, 24, 25, 27 satellites. The results show that the physical SRP model for POD and forecast for GPS IIF satellite has higher accuracy with respect to Bern empirical model. The 3D-RMS of orbit is about 20 centimeters. The POD accuracy for both models is similar but the prediction accuracy with the physical SRP model is more than doubled. We tested 1-day 3-day and 7-day orbit prediction. The longer is the prediction arc length, the more significant is the improvement. The orbit prediction accuracy with the physical SRP model for 1-day, 3-day and 7-day arc length are 0.4m, 2.0m, 10.0m respectively. But they are 0.9m, 5.5m and 30m with Bern empirical model respectively. We apply this means to the BDS and give out a SRP model for Beidou satellites. Then we test and verify the model with Beidou data of one month only for test. Initial results show the model is good but needs more data for verification and improvement. The orbit residual RMS is similar to that with our empirical force model which only estimate the force for along track, across track direction and y-bias. But the orbit overlap and SLR observation evaluation show some improvement. The remaining empirical force is reduced significantly for present Beidou constellation.
Graph theoretical model of a sensorimotor connectome in zebrafish.
Michael Stobb
Full Text Available Mapping the detailed connectivity patterns (connectomes of neural circuits is a central goal of neuroscience. The best quantitative approach to analyzing connectome data is still unclear but graph theory has been used with success. We present a graph theoretical model of the posterior lateral line sensorimotor pathway in zebrafish. The model includes 2,616 neurons and 167,114 synaptic connections. Model neurons represent known cell types in zebrafish larvae, and connections were set stochastically following rules based on biological literature. Thus, our model is a uniquely detailed computational representation of a vertebrate connectome. The connectome has low overall connection density, with 2.45% of all possible connections, a value within the physiological range. We used graph theoretical tools to compare the zebrafish connectome graph to small-world, random and structured random graphs of the same size. For each type of graph, 100 randomly generated instantiations were considered. Degree distribution (the number of connections per neuron varied more in the zebrafish graph than in same size graphs with less biological detail. There was high local clustering and a short average path length between nodes, implying a small-world structure similar to other neural connectomes and complex networks. The graph was found not to be scale-free, in agreement with some other neural connectomes. An experimental lesion was performed that targeted three model brain neurons, including the Mauthner neuron, known to control fast escape turns. The lesion decreased the number of short paths between sensory and motor neurons analogous to the behavioral effects of the same lesion in zebrafish. This model is expandable and can be used to organize and interpret a growing database of information on the zebrafish connectome.
Graph theoretical model of a sensorimotor connectome in zebrafish.
Stobb, Michael; Peterson, Joshua M; Mazzag, Borbala; Gahtan, Ethan
2012-01-01
Mapping the detailed connectivity patterns (connectomes) of neural circuits is a central goal of neuroscience. The best quantitative approach to analyzing connectome data is still unclear but graph theory has been used with success. We present a graph theoretical model of the posterior lateral line sensorimotor pathway in zebrafish. The model includes 2,616 neurons and 167,114 synaptic connections. Model neurons represent known cell types in zebrafish larvae, and connections were set stochastically following rules based on biological literature. Thus, our model is a uniquely detailed computational representation of a vertebrate connectome. The connectome has low overall connection density, with 2.45% of all possible connections, a value within the physiological range. We used graph theoretical tools to compare the zebrafish connectome graph to small-world, random and structured random graphs of the same size. For each type of graph, 100 randomly generated instantiations were considered. Degree distribution (the number of connections per neuron) varied more in the zebrafish graph than in same size graphs with less biological detail. There was high local clustering and a short average path length between nodes, implying a small-world structure similar to other neural connectomes and complex networks. The graph was found not to be scale-free, in agreement with some other neural connectomes. An experimental lesion was performed that targeted three model brain neurons, including the Mauthner neuron, known to control fast escape turns. The lesion decreased the number of short paths between sensory and motor neurons analogous to the behavioral effects of the same lesion in zebrafish. This model is expandable and can be used to organize and interpret a growing database of information on the zebrafish connectome.
The irregularities of the sunspot cycle and their theoretical modelling
Choudhuri, Arnab Rai
2013-01-01
The 11-year sunspot cycle has many irregularities, the most promi- nent amongst them being the grand minima when sunspots may not be seen for several cycles. After summarizing the relevant observational data about the irregularities, we introduce the flux transport dynamo model, the currently most successful theoretical model for explaining the 11-year sunspot cycle. Then we analyze the respective roles of nonlinearities and random fluctuations in creating the irregularities. We also discuss how it has recently been realized that the fluctuations in meridional circula- tion also can be a source of irregularities. We end by pointing out that fluctuations in the poloidal field generation and fluctuations in meridional circulation together can explain the occurrences of grand minima.
Theoretical models for Type I and Type II supernova
Woosley, S.E.; Weaver, T.A.
1985-01-01
Recent theoretical progress in understanding the origin and nature of Type I and Type II supernovae is discussed. New Type II presupernova models characterized by a variety of iron core masses at the time of collapse are presented and the sensitivity to the reaction rate /sup 12/C(..cap alpha..,..gamma..)/sup 16/O explained. Stars heavier than about 20 M/sub solar/ must explode by a ''delayed'' mechanism not directly related to the hydrodynamical core bounce and a subset is likely to leave black hole remnants. The isotopic nucleosynthesis expected from these massive stellar explosions is in striking agreement with the sun. Type I supernovae result when an accreting white dwarf undergoes a thermonuclear explosion. The critical role of the velocity of the deflagration front in determining the light curve, spectrum, and, especially, isotopic nucleosynthesis in these models is explored. 76 refs., 8 figs.
Theoretical model of intravascular paramagnetic tracers effect on tissue relaxation
Kjølby, Birgitte Fuglsang; Østergaard, Leif; Kiselev, Valerij G
2006-01-01
that the relaxivity of intravascular contrast agents depends significantly on the host tissue. This agrees with experimental data by Johnson et al. (Magn Reson Med 2000;44:909). In particular, the present results suggest a several-fold increase in the relaxivity of Gd-based contrast agents in brain tissue compared...... with bulk blood. The enhancement of relaxation in tissue is due to the contrast in magnetic susceptibility between blood vessels and parenchyma induced by the presence of paramagnetic tracer. Beyond the perfusion measurements, the results can be applied to quantitation of functional MRI and to vessel size......The concentration of MRI tracers cannot be measured directly by MRI and is commonly evaluated indirectly using their relaxation effect. This study develops a comprehensive theoretical model to describe the transverse relaxation in perfused tissue caused by intravascular tracers. The model takes...
Validation of theoretical models through measured pavement response
Ullidtz, Per
1999-01-01
performance. The analytical models are based on a number of simplifications with respect to reality and must be verified experimentally.Different pressure gauges were installed in a sand, assumed to be a semi-infinite halfspace. The surface of the sand was loaded by a Falling Weight Deflectometer (FWD......) at different lateral positions with respect to the gauges. An integration of the stresses measured at the plane of the gauges showed that the total load recorded by the gauges was close to the loade imposed by the FWD, cofirming the reliability of the gauges. The theoretical stress calculated using continuum...... then used to derive the elastic parameters of the pavement layeres, that would produce deflections matching the measured deflections. Stresses and strains were then calculated at the position of the gauges and compared to the measured values. It was found that all analytical models would predict the tensile...
A Lifecourse Model of Multimorbidity Resilience: Theoretical and Research Developments.
Wister, Andrew V; Coatta, Katherine L; Schuurman, Nadine; Lear, Scott A; Rosin, Miriam; MacKey, Dawn
2016-04-01
The purpose of this article is to advance a Lifecourse Model of Multimorbidity Resilience. It focuses on the ways in which individuals face adversities associated with multimorbidity and regain a sense of wellness through a complex, dynamic phenomenon termed resilience. A comprehensive review of 112 publications (between 1995 and 2015) was conducted using several comprehensive electronic data bases. Two independent researchers extracted and synthesized resilience literature with specific applications to chronic illness. The article outlines five stages of theoretical development of resilience, synthesizes these with the aging and chronic illness literature, builds a rationale for a lifecourse approach to resilience, and applies the model to multimorbidity. Cultivating and maintaining resilience is fundamental to functioning and quality of life for those with multimorbidity. We found that there are a number of gaps in both basic and applied research that need to be filled to advance knowledge and practice based on resilience approaches.
Recent advances in theoretical models of respiratory mechanics
Bo Huo; Rui-Rong Fu
2012-01-01
As an important branch of biomedical engineering,respiratory mechanics helps to understand the physiology of the respiratory system and provides fundamental data for developing such clinical technologies as ventilators.To solve different clinical problems,researchers have developed numerous models at various scales that describe biological and mechanical properties of the respiratory system.During the past decade,benefiting from the continuous accumulation of clinical data and the dramatic progress of biomedical technologies (e.g.biomedical imaging),the theoretical modeling of respiratory mechanics has made remarkable progress regarding the macroscopic properties of the respiratory process,complexities of the respiratory system,gas exchange within the lungs,and the coupling interaction between lung and heart.The present paper reviews the advances in the above fields and proposes potential future projects.
Theoretical modelling of non-symmetric circular piezoelectric bimorphs
Brissaud, Michel
2006-05-01
This paper deals with the theoretical modelling of non-symmetric and symmetric circular bimorphs. The model is restricted to the study of flexural vibration modes having radial symmetry (axisymmetry), as is often the case for piezoelectric devices such as MEMs. The calculation of the resonance frequencies and the displacement of the non-symmetric circular bimorph has been carried out and the influence of the elastic and geometric parameters of the cement layer has been introduced into the model. As is shown, the modelling of non-symmetric and symmetric circular bimorphs reduces to the determination of two global quantities: the global rigidity DG and the global Poisson ratio σG of the bimorph which is then equivalent to a homogenous element. Consequently, the results obtained with elastic and homogeneous circular plates can be applied to non-symmetric and symmetric bimorphs with the only condition of using the global DG and σG. The new modelling was applied to bimorph functioning either as an actuator or as a sensor and having a simply supported or clamped edge. The electromechanical coupling factor of flexure modes has been calculated and compared to the radial mode. Comparison between analytical models and simulations using the finite-element method is given and discussed.
Raindrop size distribution: Fitting performance of common theoretical models
Adirosi, E.; Volpi, E.; Lombardo, F.; Baldini, L.
2016-10-01
Modelling raindrop size distribution (DSD) is a fundamental issue to connect remote sensing observations with reliable precipitation products for hydrological applications. To date, various standard probability distributions have been proposed to build DSD models. Relevant questions to ask indeed are how often and how good such models fit empirical data, given that the advances in both data availability and technology used to estimate DSDs have allowed many of the deficiencies of early analyses to be mitigated. Therefore, we present a comprehensive follow-up of a previous study on the comparison of statistical fitting of three common DSD models against 2D-Video Distrometer (2DVD) data, which are unique in that the size of individual drops is determined accurately. By maximum likelihood method, we fit models based on lognormal, gamma and Weibull distributions to more than 42.000 1-minute drop-by-drop data taken from the field campaigns of the NASA Ground Validation program of the Global Precipitation Measurement (GPM) mission. In order to check the adequacy between the models and the measured data, we investigate the goodness of fit of each distribution using the Kolmogorov-Smirnov test. Then, we apply a specific model selection technique to evaluate the relative quality of each model. Results show that the gamma distribution has the lowest KS rejection rate, while the Weibull distribution is the most frequently rejected. Ranking for each minute the statistical models that pass the KS test, it can be argued that the probability distributions whose tails are exponentially bounded, i.e. light-tailed distributions, seem to be adequate to model the natural variability of DSDs. However, in line with our previous study, we also found that frequency distributions of empirical DSDs could be heavy-tailed in a number of cases, which may result in severe uncertainty in estimating statistical moments and bulk variables.
A theoretical model for assessing the sustainability Of ecosystem services
Feng Ling; Cheng Shengkui; Su Hua; Min Qingwen
2008-01-01
The Value of the World's Ecosystem Services and Natural Capital by Costanza in 1997 is generally regarded as a monument for the research of valuing ecosystem services. However, the classification of ecosystem services, the method of various services summation and the purpose for static global value had be confronted by many criticisms. Based on the summary of these criticisms, suggestions, related function assessment and further study direction, the sustainability of ecosystem services is presented The two basic indicators in ecology, productivity and biodiversity, respectively charactering the ability of producing and self-organizing, not only represent the internal function of ecosystem, but also are proportioned to its external function of supporting and providing for human life On presenting the general form of ecosystem services assessment, this paper improves the mathematical formula giving a function adjusting coefficient composed of productivity and biodiversity. Theoretically, the integration of the two indicators reflects the changes of ecosystem services at spatial and temporal scales, can physically assess the sustability of ecosystem services, and build a firm scientific fundament of value assessment for ecosystem services Objectively, its application should be strictly tested in next step.Ecosystem services; theoretical model; Sustainability; Bio-productivity; Biodiversity
Emotional Belief-Desire-Intention Agent Model: Previous Work And Proposed Architecture
Mihaela- Alexandra Puica
2013-02-01
Full Text Available Research in affective computing shows that agents cannot be truly intelligent, nor believable or realistic without emotions. In this paper, we present a model of emotional agents that is based on a BDI architecture. We show how we can integrate emotions, resources and personality features into an artificial intelligent agent so as to obtain a human-like behavior of this agent. We place our work in the general context of existing research in emotional agents, with emphasis on BDI emotional models.
Spatial Segregation, Redistribution and Welfare: A Theoretical Model
Tommaso Gabrieli
2016-03-01
Full Text Available This paper develops a theoretical model focusing on the effect that different neighborhood compositions can have on the formation of individual beliefs about economic opportunities. Specifically we highlight two effects that spatial segregation may have: (1 it can efficiently separate the individual effort choices of highly and low productive individuals, (2 it may imply that the median voter imposes a level of redistribution that is inefficient from the aggregate point of view. The trade-off implies that segregated and non-segregated cities may present very similar levels of aggregate welfare. We employ this framework to discuss how the structure of cities can play a role in the determination of US-type and Europe-type politico-economic equilibria and the implications for planning policies.
Exploring a type-theoretic approach to accessibility constraint modelling
Pogodalla, Sylvain
2008-01-01
The type-theoretic modelling of DRT that [degroote06] proposed features continuations for the management of the context in which a clause has to be interpreted. This approach, while keeping the standard definitions of quantifier scope, translates the rules of the accessibility constraints of discourse referents inside the semantic recipes. In this paper, we deal with additional rules for these accessibility constraints. In particular in the case of discourse referents introduced by proper nouns, that negation does not block, and in the case of rhetorical relations that structure discourses. We show how this continuation-based approach applies to those accessibility constraints and how we can consider the parallel management of various principles.
Examining Asymmetrical Relationships of Organizational Learning Antecedents: A Theoretical Model
Ery Tri Djatmika
2016-02-01
Full Text Available Global era is characterized by highly competitive advantage market demand. Responding to the challenge of rapid environmental changes, organizational learning is becoming a strategic way and solution to empower people themselves within the organization in order to create a novelty as valuable positioning source. For research purposes, determining the influential antecedents that affect organizational learning is vital to understand research-based solutions given for practical implications. Accordingly, identification of variables examined by asymmetrical relationships is critical to establish. Possible antecedent variables come from organizational and personal point of views. It is also possible to include a moderating one. A proposed theoretical model of asymmetrical effects of organizational learning and its antecedents is discussed in this article.
Theoretical temperature model with experimental validation for CLIC Accelerating Structures
AUTHOR|(CDS)2126138; Vamvakas, Alex; Alme, Johan
Micron level stability of the Compact Linear Collider (CLIC) components is one of the main requirements to meet the luminosity goal for the future $48 \\,km$ long underground linear accelerator. The radio frequency (RF) power used for beam acceleration causes heat generation within the aligned structures, resulting in mechanical movements and structural deformations. A dedicated control of the air- and water- cooling system in the tunnel is therefore crucial to improve alignment accuracy. This thesis investigates the thermo-mechanical behavior of the CLIC Accelerating Structure (AS). In CLIC, the AS must be aligned to a precision of $10\\,\\mu m$. The thesis shows that a relatively simple theoretical model can be used within reasonable accuracy to predict the temperature response of an AS as a function of the applied RF power. During failure scenarios or maintenance interventions, the RF power is turned off resulting in no heat dissipation and decrease in the overall temperature of the components. The theoretica...
A theoretical model of phase transitions in the human brain.
Jirsa, V K; Friedrich, R; Haken, H; Kelso, J A
1994-01-01
An experiment using a multisensor SQUID (superconducting quantum interference device) array was performed by Kelso and colleagues (1992) which combined information from three different sources: perception, motor response, and brain signals. When an acoustic stimulus frequency is changed systematically, a spontaneous transition in coordination occurs at a critical frequency in both motor behavior and brain signals. Qualitatively analogous transitions are known for physical and biological systems such as changes in the coordination of human hand movements (Kelso 1981, 1984). In this paper we develop a theoretical model based on methods from the interdisciplinary field of synergetics (Haken 1983, 1987) and nonlinear oscillator theory that reproduces the main experimental features very well and suggests a formulation of a fundamental biophysical coupling.
A model theoretic Baire category theorem for simple theories
Shami, Ziv
2009-01-01
We define the class of $\\tilde\\tau_{low}^f$-sets. This is a class of type-definable sets defined in terms of forking by low formulas. We prove a model theoretic Baire category theorem for $\\tilde\\tau_{low}^f$-sets in a countable simple theory in which the extension property is first-order and show some of its applications. A typical application is the following. Let $T$ be a countable theory with the wnfcp (weak nonfinite cover property) and assume for every non-algebraic $a$ there exists a non-algebraic $a'\\acl(a)$ such that $SU(a')<\\omega$. Then there exists a weakly-minimal formula with parameters.
Penetration of alkali atoms throughout a graphene membrane: theoretical modeling.
Boukhvalov, D W; Virojanadara, C
2012-03-07
Theoretical studies of penetration of various alkali atoms (Li, Na, Rb, Cs) throughout a graphene membrane grown on a silicon carbide substrate are reported and compared with recent experimental results. Results of first principles modeling demonstrate a rather low (about 0.8 eV) energy barrier for the formation of temporary defects in the carbon layer required for the penetration of Li at a high concentration of adatoms, a higher (about 2 eV) barrier for Na, and barriers above 4 eV for Rb and Cs. Experiments prove migration of lithium adatoms from the graphene surface to the buffer layer and SiC substrate at room temperature, sodium at 100 °C and impenetrability of the graphene membrane for Rb and Cs. Differences between epitaxial and free-standing graphene for the penetration of alkali ions are also discussed.
Literature Survey of previous research work in Models and Methodologies in Project Management
Ravinder Singh; Dr. Kevin Lano
2014-01-01
This paper provides a survey of the existing literature and research carried out in the area of project management using different models, methodologies, and frameworks. Project Management (PM) broadly means programme management, portfolio management, practice management, project management office, etc. A project management system has a set of processes, procedures, framework, methods, tools, methodologies, techniques, resources, etc. which are used to manage the full life cycle of projects. ...
Theoretical model for forming limit diagram predictions without initial inhomogeneity
Gologanu, Mihai; Comsa, Dan Sorin; Banabic, Dorel
2013-05-01
We report on our attempts to build a theoretical model for determining forming limit diagrams (FLD) based on limit analysis that, contrary to the well-known Marciniak and Kuczynski (M-K) model, does not assume the initial existence of a region with material or geometrical inhomogeneity. We first give a new interpretation based on limit analysis for the onset of necking in the M-K model. Considering the initial thickness defect along a narrow band as postulated by the M-K model, we show that incipient necking is a transition in the plastic mechanism from one of plastic flow in both the sheet and the band to another one where the sheet becomes rigid and all plastic deformation is localized in the band. We then draw on some analogies between the onset of necking in a sheet and the onset of coalescence in a porous bulk body. In fact, the main advance in coalescence modeling has been based on a similar limit analysis with an important new ingredient: the evolution of the spatial distribution of voids, due to the plastic deformation, creating weaker regions with higher porosity surrounded by sound regions with no voids. The onset of coalescence is precisely the transition from a mechanism of plastic deformation in both regions to another one, where the sound regions are rigid. We apply this new ingredient to a necking model based on limit analysis, for the first quadrant of the FLD and a porous sheet. We use Gurson's model with some recent extensions to model the porous material. We follow both the evolution of a homogeneous sheet and the evolution of the distribution of voids. At each moment we test for a potential change of plastic mechanism, by comparing the stresses in the uniform region to those in a virtual band with a larger porosity. The main difference with the coalescence of voids in a bulk solid is that the plastic mechanism for a sheet admits a supplementary degree of freedom, namely the change in the thickness of the virtual band. For strain ratios close to
Literature Survey of previous research work in Models and Methodologies in Project Management
Ravinder Singh
2014-09-01
Full Text Available This paper provides a survey of the existing literature and research carried out in the area of project management using different models, methodologies, and frameworks. Project Management (PM broadly means programme management, portfolio management, practice management, project management office, etc. A project management system has a set of processes, procedures, framework, methods, tools, methodologies, techniques, resources, etc. which are used to manage the full life cycle of projects. This also means to create risk, quality, performance, and other management plans to monitor and manage the projects efficiently and effectively.
Whitton, R Christopher; Trope, Gareth D; Ghasem-Zadeh, Ali; Anderson, Garry A; Parkin, Timothy D H; Mackie, Eleanor J; Seeman, Ego
2010-10-01
Bone modelling and remodelling reduce the risk of fatigue fractures; the former by adapting bone to its loading circumstances, the latter by replacing fatigued bone. Remodelling transiently increases porosity because of the normal delay in onset of the formation phase of the remodelling sequence. Protracted intense loading suppresses remodelling leaving modelling as the only means of maintaining bone strength. We therefore hypothesized that race horses with fatigue fractures of the distal third metacarpal bone (MC3) will have reduced porosity associated with suppressed remodelling while continued adaptive modelling will result in higher volume fraction (BV/TV) at this site. Using high resolution peripheral quantitative computed tomography (HR-pQCT), we measured the distal aspect of the MC3 obtained at postmortem from 13 thoroughbred race horses with condylar fractures of the MC3 (cases), 8 horses without fractures (training controls), 14 horses with a fracture at another site (fractured controls) and 9 horses resting from training (resting controls). Porosity of the subchondral bone of MC3 was lower in cases than resting controls (12±1.4% vs. 18±1.6%, P=0.017) although areas of focal porosity were observed adjacent to fractures in 6/13 horses. BV/TV of the distal metacarpal epiphysis tended to be higher in horses with condylar fractures (0.79±0.015) than training controls (0.74±0.019, P=0.070), but also higher in controls with a fracture elsewhere (0.79±0.014) than the training controls (0.74±0.019, P=0.040). BV/TV was higher in horses over three years of age than those aged two or three years (0.79±0.01 vs. 0.74±0.01, P=0.016). All metacarpal condylar fractures occurred within focal areas of high BV/TV. We infer that intense training in equine athletes suppresses remodelling of third metacarpal subchondral bone limiting damage repair while modelling increases regional bone volume in an attempt to minimise local stresses but may fail to offset bone
Modelling Crowd Dynamics: a Multiscale, Measure-theoretical Approach
Evers, Joep
2011-01-01
We present a strategy capable of describing basic features of the dynamics of crowds. The behaviour of the crowd is considered from a twofold perspective. We examine both the large scale behaviour of the crowd, and phenomena happening at the individual pedestrian's level. We unify micro and macro in a single model, by working with general mass measures and their transport. We improve existing modelling by coupling a measure-theoretical framework with basic ideas of mixture theory formulated in terms of measures. This strategy allows us to define several constituents of the crowd, each having its own partial velocity. We can thus examine the interaction between subpopulations that have distinct characteristics. We give special features to those pedestrians that are represented by the microscopic (discrete) part. In real life they would play the role of leaders, predators etc. Since we are interested in the global behaviour of the rest of the crowd, we model this part as a continuum. By identifying a suitable c...
A theoretical intellectual capital model applied to cities
José Luis Alfaro Navarro
2013-06-01
Full Text Available New Management Information Systems (MIS are necessary at local level as the main source of wealth creation. Therefore, tools and approaches that provide a full future vision of any organization should be a strategic priority for economic development. In this line, cities are “centers of knowledge and sources of growth and innovation” and integrated urban development policies are necessary. These policies support communication networks and optimize location structures as strategies that provide opportunities for social and democratic participation for the citizens. This paper proposes a theoretical model to measure and evaluate the cities intellectual capital that allows determine what we must take into account to make cities a source of wealth, prosperity, welfare and future growth. Furthermore, local intellectual capital provides a long run vision. Thus, in this paper we develop and explain how to implement a model to estimate intellectual capital in cities. In this sense, our proposal is to provide a model for measuring and managing intellectual capital using socio-economic indicators for cities. These indicators offer a long term picture supported by a comprehensive strategy for those who occupy the local space, infrastructure for implementation and management of the environment for its development.
A Production Model for Construction: A Theoretical Framework
Ricardo Antunes
2015-03-01
Full Text Available The building construction industry faces challenges, such as increasing project complexity and scope requirements, but shorter deadlines. Additionally, economic uncertainty and rising business competition with a subsequent decrease in profit margins for the industry demands the development of new approaches to construction management. However, the building construction sector relies on practices based on intuition and experience, overlooking the dynamics of its production system. Furthermore, researchers maintain that the construction industry has no history of the application of mathematical approaches to model and manage production. Much work has been carried out on how manufacturing practices apply to construction projects, mostly lean principles. Nevertheless, there has been little research to understand the fundamental mechanisms of production in construction. This study develops an in-depth literature review to examine the existing knowledge about production models and their characteristics in order to establish a foundation for dynamic production systems management in construction. As a result, a theoretical framework is proposed, which will be instrumental in the future development of mathematical production models aimed at predicting the performance and behaviour of dynamic project-based systems in construction.
A theoretical model for the associative nature of conference participation
Smiljanić, Jelena; Kauppinen, Tomi; Dankulov, Marija Mitrović
2015-01-01
Participation in conferences is an important part of every scientific career. Conferences provide an opportunity for a fast dissemination of latest results, discussion and exchange of ideas, and broadening of scientists' collaboration network. The decision to participate in a conference depends on several factors like the location, cost, popularity of keynote speakers, and the scientists' association with the community. Here we discuss and formulate the problem of discovering how a scientists' previous participation affects her/his future participations in the same conference series. We develop a stochastic model to examine scientists' participation patterns in conferences and compare our model with data from six conferences across various scientific fields and communities. Our model shows that the probability for a scientist to participate in a given conference series strongly depends on the balance between the number of participations and non-participations during his/her early connections with the communit...
Hernández, B; Peña, E; Pascual, G; Rodríguez, M; Calvo, B; Doblaré, M; Bellón, J M
2011-04-01
The aims of this study are to experimentally characterize the passive elastic behaviour of the rabbit abdominal wall and to develop a mechanical constitutive law which accurately reproduces the obtained experimental results. For this purpose, tissue samples from New Zealand White rabbits 2150±50 (g) were mechanically tested in vitro. Mechanical tests, consisting of uniaxial loading on tissue samples oriented along the craneo-caudal and the perpendicular directions, respectively, revealed the anisotropic non-linear mechanical behaviour of the abdominal tissues. Experiments were performed considering the composite muscle (including external oblique-EO, internal oblique-IO and transverse abdominis-TA muscle layers), as well as separated muscle layers (i.e., external oblique, and the bilayer formed by internal oblique and transverse abdominis). Both the EO muscle layer and the IO-TA bilayer demonstrated a stiffer behaviour along the transversal direction to muscle fibres than along the longitudinal one. The fibre arrangement was measured by means of a histological study which confirmed that collagen fibres are mainly responsible for the passive mechanical strength and stiffness. Furthermore, the degree of anisotropy of the abdominal composite muscle turned out to be less pronounced than those obtained while studying the EO and IO-TA separately. Moreover, a phenomenological constitutive law was used to capture the measured experimental curves. A Levenberg-Marquardt optimization algorithm was used to fit the model constants to reproduce the experimental curves. Copyright © 2010 Elsevier Ltd. All rights reserved.
Pérez-Rial, Sandra; Del Puerto-Nevado, Laura; Girón-Martínez, Alvaro; Terrón-Expósito, Raúl; Díaz-Gil, Juan J; González-Mangado, Nicolás; Peces-Barba, Germán
2014-11-01
Chronic obstructive pulmonary disease (COPD) is an inflammatory lung disease largely associated with cigarette smoke exposure (CSE) and characterized by pulmonary and extrapulmonary manifestations, including systemic inflammation. Liver growth factor (LGF) is an albumin-bilirubin complex with demonstrated antifibrotic, antioxidant, and antihypertensive actions even at extrahepatic sites. We aimed to determine whether short LGF treatment (1.7 μg/mouse ip; 2 times, 2 wk), once the lung damage was established through the chronic CSE, contributes to improvement of the regeneration of damaged lung tissue, reducing systemic inflammation. We studied AKR/J mice, divided into three groups: control (air-exposed), CSE (chronic CSE), and CSE + LGF (LGF-treated CSE mice). We assessed pulmonary function, morphometric data, and levels of various systemic inflammatory markers to test the LGF regenerative capacity in this system. Our results revealed that the lungs of the CSE animals showed pulmonary emphysema and inflammation, characterized by increased lung compliance, enlargement of alveolar airspaces, systemic inflammation (circulating leukocytes and serum TNF-α level), and in vivo lung matrix metalloproteinase activity. LGF treatment was able to reverse all these parameters, decreasing total cell count in bronchoalveolar lavage fluid and T-lymphocyte infiltration in peripheral blood observed in emphysematous mice and reversing the decrease in monocytes observed in chronic CSE mice, and tends to reduce the neutrophil population and serum TNF-α level. In conclusion, LGF treatment normalizes the physiological and morphological parameters and levels of various systemic inflammatory biomarkers in a chronic CSE AKR/J model, which may have important pathophysiological and therapeutic implications for subjects with stable COPD.
Theoretical modeling of the absorption spectrum of aqueous riboflavin
Zanetti-Polzi, Laura; Aschi, Massimiliano; Daidone, Isabella; Amadei, Andrea
2017-02-01
In this study we report the modeling of the absorption spectrum of riboflavin in water using a hybrid quantum/classical mechanical approach, the MD-PMM methodology. By means of MD-PMM calculations, with which the effect of riboflavin internal motions and of solvent interactions on the spectroscopic properties can be explicitly taken into account, we obtain an absorption spectrum in very good agreement with the experimental spectrum. In particular, the calculated peak maxima show a consistent improvement with respect to previous computational approaches. Moreover, the calculations show that the interaction with the environment may cause a relevant recombination of the gas-phase electronic states.
Experimental Investigation and Theoretical Modeling of Nanosilica Activity in Concrete
Han-Seung Lee
2014-01-01
Full Text Available This paper presents experimental investigations and theoretical modeling of the hydration reaction of nanosilica blended concrete with different water-to-binder ratios and different nanosilica replacement ratios. The developments of chemically bound water contents, calcium hydroxide contents, and compressive strength of Portland cement control specimens and nanosilica blended specimens were measured at different ages: 1 day, 3 days, 7 days, 14 days, and 28 days. Due to the pozzolanic reaction of nanosilica, the contents of calcium hydroxide in nanosilica blended pastes are considerably lower than those in the control specimens. Compared with the control specimens, the extent of compressive strength enhancement in the nanosilica blended specimens is much higher at early ages. Additionally, a blended cement hydration model that considers both the hydration reaction of cement and the pozzolanic reaction of nanosilica is proposed. The properties of nanosilica blended concrete during hardening were evaluated using the degree of hydration of cement and the reaction degree of nanosilica. The calculated chemically bound water contents, calcium hydroxide contents, and compressive strength were generally consistent with the experimental results.
Strengthening Theoretical Testing in Criminology Using Agent-based Modeling.
Johnson, Shane D; Groff, Elizabeth R
2014-07-01
The Journal of Research in Crime and Delinquency (JRCD) has published important contributions to both criminological theory and associated empirical tests. In this article, we consider some of the challenges associated with traditional approaches to social science research, and discuss a complementary approach that is gaining popularity-agent-based computational modeling-that may offer new opportunities to strengthen theories of crime and develop insights into phenomena of interest. Two literature reviews are completed. The aim of the first is to identify those articles published in JRCD that have been the most influential and to classify the theoretical perspectives taken. The second is intended to identify those studies that have used an agent-based model (ABM) to examine criminological theories and to identify which theories have been explored. Ecological theories of crime pattern formation have received the most attention from researchers using ABMs, but many other criminological theories are amenable to testing using such methods. Traditional methods of theory development and testing suffer from a number of potential issues that a more systematic use of ABMs-not without its own issues-may help to overcome. ABMs should become another method in the criminologists toolbox to aid theory testing and falsification.
Studies of Chinese speakers with dysarthria: informing theoretical models.
Whitehill, Tara L
2010-01-01
Most theoretical models of dysarthria have been developed based on research using individuals speaking English or other Indo-European languages. Studies of individuals with dysarthria speaking other languages can allow investigation into the universality of such models, and the interplay between language-specific and language-universal aspects of dysarthria. In this article, studies of Cantonese- and Mandarin-Chinese speakers with dysarthria are reviewed. The studies focused on 2 groups of speakers: those with cerebral palsy and those with Parkinson's disease. Key findings are compared with similar studies of English speakers. Since Chinese is tonal in nature, the impact of dysarthria on lexical tone has received considerable attention in the literature. The relationship between tone [which involves fundamental frequency (F(0)) control at the syllable level] and intonation (involving F(0) control at the sentential level) has received more recent attention. Many findings for Chinese speakers with dysarthria support earlier findings for English speakers, thus affirming the language-universal aspect of dysarthria. However, certain differences, which can be attributed to the distinct phonologies of Cantonese and Mandarin, highlight the language-specific aspects of the condition.
Theoretical Model and Dynamic Analysis of Soft Yoke Mooring System
无
2008-01-01
As a popular solution for mooring an FPSO (Floating Production, Storage and Offloading) permanently in shallow water, the soft yoke mooring system has been widely used in ocean oil production activities in the Bohai Bay of China. In order to simulate the interaction mechanism and conduct dynamic analysis of the soft yoke mooring system, a theoretical model with basic dynamic equations is established. A numerical iteration algorithm based on error estimation is developed to solve the equations and calculate the dynamic response of the mooring system due to FPSO motions. Validation is conducted by wave basin experimentation. It is shown that the numerical simulation takes only a few iteration times and the final errors are small. Furthermore, the calculated results of both the static and dynamic responses agree well with those ones obtained by the model test. It indicates that the efficiency, the precision, the reliability and the validity of the developed numerical algorithm and program are rather good. It is proposed to develop a real-time monitoring system to further monitor the dynamic performance of the FPSO with a soft yoke mooring system under various real sea environments.
A theoretical model for analysing gender bias in medicine
Johansson Eva E
2009-08-01
Full Text Available Abstract During the last decades research has reported unmotivated differences in the treatment of women and men in various areas of clinical and academic medicine. There is an ongoing discussion on how to avoid such gender bias. We developed a three-step-theoretical model to understand how gender bias in medicine can occur and be understood. In this paper we present the model and discuss its usefulness in the efforts to avoid gender bias. In the model gender bias is analysed in relation to assumptions concerning difference/sameness and equity/inequity between women and men. Our model illustrates that gender bias in medicine can arise from assuming sameness and/or equity between women and men when there are genuine differences to consider in biology and disease, as well as in life conditions and experiences. However, gender bias can also arise from assuming differences when there are none, when and if dichotomous stereotypes about women and men are understood as valid. This conceptual thinking can be useful for discussing and avoiding gender bias in clinical work, medical education, career opportunities and documents such as research programs and health care policies. Too meet the various forms of gender bias, different facts and measures are needed. Knowledge about biological differences between women and men will not reduce bias caused by gendered stereotypes or by unawareness of health problems and discrimination associated with gender inequity. Such bias reflects unawareness of gendered attitudes and will not change by facts only. We suggest consciousness-rising activities and continuous reflections on gender attitudes among students, teachers, researchers and decision-makers.
Theoretical Modelling Methods for Thermal Management of Batteries
Bahman Shabani
2015-09-01
Full Text Available The main challenge associated with renewable energy generation is the intermittency of the renewable source of power. Because of this, back-up generation sources fuelled by fossil fuels are required. In stationary applications whether it is a back-up diesel generator or connection to the grid, these systems are yet to be truly emissions-free. One solution to the problem is the utilisation of electrochemical energy storage systems (ESS to store the excess renewable energy and then reusing this energy when the renewable energy source is insufficient to meet the demand. The performance of an ESS amongst other things is affected by the design, materials used and the operating temperature of the system. The operating temperature is critical since operating an ESS at low ambient temperatures affects its capacity and charge acceptance while operating the ESS at high ambient temperatures affects its lifetime and suggests safety risks. Safety risks are magnified in renewable energy storage applications given the scale of the ESS required to meet the energy demand. This necessity has propelled significant effort to model the thermal behaviour of ESS. Understanding and modelling the thermal behaviour of these systems is a crucial consideration before designing an efficient thermal management system that would operate safely and extend the lifetime of the ESS. This is vital in order to eliminate intermittency and add value to renewable sources of power. This paper concentrates on reviewing theoretical approaches used to simulate the operating temperatures of ESS and the subsequent endeavours of modelling thermal management systems for these systems. The intent of this review is to present some of the different methods of modelling the thermal behaviour of ESS highlighting the advantages and disadvantages of each approach.
a Theoretical Model of a Superheated Liquid Droplet Neutron Detector.
Harper, Mark Joseph
Neutrons can interact with the atoms in superheated liquid droplets which are suspended in a viscous matrix material, resulting in the formation of charged recoil ions. These ions transfer energy to the liquid, sometimes resulting in the droplets vaporizing and producing observable bubbles. Devices employing this mechanism are known as superheated liquid droplet detectors, or bubble detectors. The basis of bubble detector operation is identical to that of bubble chambers, which have been well characterized by researchers such as Wilson, Glaser, Seitz, and others since the 1950's. Each of the microscopic superheated liquid droplets behaves like an independent bubble chamber. This dissertation presents a theoretical model which considers the three principal aspects of detector operation: nuclear reactions, charged particle energy deposition, and thermodynamic bubble formation. All possible nuclear reactions were examined and those which could reasonably result in recoil ions sufficiently energetic to vaporize a droplet were analyzed in detail. Feasible interactions having adequate cross sections include elastic and inelastic scattering, n-proton, and n-alpha reactions. Ziegler's TRansport of Ions in Matter (TRIM) code was used to calculate the ions' stopping powers in various compounds based on the ionic energies predicted by standard scattering distributions. If the ions deposit enough energy in a small enough volume then the entire droplet will vaporize without further energy input. Various theories as to the vaporization of droplets by ionizing radiation were studied and a novel method of predicting the critical (minimum) energy was developed. This method can be used to calculate the minimum required stopping power for the ion, from which the threshold neutron energy is obtainable. Experimental verification of the model was accomplished by measuring the response of two different types of bubble detectors to monoenergetic thermal neutrons, as well as to neutrons
Models in Educational Administration: Revisiting Willower's "Theoretically Oriented" Critique
Newton, Paul; Burgess, David; Burns, David P.
2010-01-01
Three decades ago, Willower (1975) argued that much of what we take to be theory in educational administration is in fact only theoretically oriented. If we accept Willower's assessment of the field as true, what implications does this statement hold for the academic study and practical application of the theoretically oriented aspects of our…
Theoretical model of superconducting spintronic SIsFS devices
Bakurskiy, S. V.; Klenov, N. V.; Soloviev, I. I.; Bol'ginov, V. V.; Ryazanov, V. V.; Vernik, I. V.; Mukhanov, O. A.; Kupriyanov, M. Yu.; Golubov, A. A.
2013-05-01
Motivated by recent progress in the development of cryogenic memory compatible with single flux quantum (SFQ) circuits, we have performed a theoretical study of magnetic SIsFS Josephson junctions, where "S" is a bulk superconductor, "s" is a thin superconducting film, "F" is a metallic ferromagnet, and "I" is an insulator. We calculate the Josephson current as a function of s and F layers thickness, temperature, and exchange energy of F film. We outline several modes of operation of these junctions and demonstrate their unique ability to have large product of a critical current IC and a normal-state resistance RN in the π state, comparable to that in superconductor-insulator-superconductor tunnel junctions commonly used in SFQ circuits. We develop a model describing switching of the Josephson critical current in these devices by external magnetic field. The results are in good agreement with the experimental data for Nb-Al/AlOx-Nb-Pd0.99Fe0.01-Nb junctions.
Measuring and Managing Value Co-Creation Process: Overview of Existing Theoretical Models
Monika Skaržauskaitė
2013-08-01
Full Text Available Purpose — the article is to provide a holistic view on concept of value co-creation and existing models for measuring and managing it by conducting theoretical analysis of scientific literature sources targeting the integration of various approaches. Most important and relevant results of the literature study are presented with a focus on changed roles of organizations and consumers. This article aims at contributing theoretically to the research stream of measuring co-creation of value in order to gain knowledge for improvement of organizational performance and enabling new and innovative means of value creation. Design/methodology/approach. The nature of this research is exploratory – theoretical analysis and synthesis of scientific literature sources targeting the integration of various approaches was performed. This approach was chosen due to the absence of established theory on models of co-creation, possible uses in organizations and systematic overview of tools measuring/suggesting how to measure co-creation. Findings. While the principles of managing and measuring co-creation in regards of consumer motivation and involvement are widely researched, little attempt has been made to identify critical factors and create models dealing with organizational capabilities and managerial implications of value co-creation. Systematic analysis of literature revealed a gap not only in empirical research concerning organization’s role in co-creation process, but in theoretical and conceptual levels, too. Research limitations/implications. The limitations of this work as a literature review lies in its nature – the complete reliance on previously published research papers and the availability of these studies. For a deeper understanding of co-creation management and for developing models that can be used in real-life organizations, a broader theoretical, as well as empirical, research is necessary. Practical implications. Analysis of the
Theoretical Modeling of ISO Results on Planetary Nebula NGC 7027
Yan, M.; Federman, S. R.; Dalgarno, A.; Bjorkman, J. E.
1999-04-01
We present a thermal and chemical model of the neutral envelope of planetary nebula NGC 7027. In our model, the neutral envelope is composed of a thin dense shell of constant density and an outer stellar wind region with the usual inverse-square law density profile. The thermal and chemical structure is calculated with the assumption that the incident radiation field on the inner surface equals 0.5×105 times Draine's fit to the average interstellar far-ultraviolet field. The rate coefficient for H2 formation on grains is assumed to be 1/5 the usual value to take into account the lower dust-gas mass ratio in the neutral envelope of NGC 7027. The calculated temperature in the dense shell decreases from 3000 to under 200 K. Once the temperature drops to 200 K, we assume that it remains at 200 K until the outer edge of the dense shell is reached, so that the observed intensities of CO J=16-15, 15-14, and 14-13 lines can be reproduced. The 200 K temperature can be interpreted as the average temperature of the shocked gas just behind the forward shock front in the framework of the interacting stellar wind theory. We calculate the intensities of the molecular far-infrared rotational lines by using a revised version of the escape probability formalism. The theoretical intensities for rotational lines of CO (from J=29-28 to J=14-13), CH+, OH, and CH are shown to be in good agreement with ISO observations. The H2 rovibrational line intensities are also calculated and are in agreement with available observations.
A Theoretical Model for the Associative Nature of Conference Participation.
Jelena Smiljanić
Full Text Available Participation in conferences is an important part of every scientific career. Conferences provide an opportunity for a fast dissemination of latest results, discussion and exchange of ideas, and broadening of scientists' collaboration network. The decision to participate in a conference depends on several factors like the location, cost, popularity of keynote speakers, and the scientist's association with the community. Here we discuss and formulate the problem of discovering how a scientist's previous participation affects her/his future participations in the same conference series. We develop a stochastic model to examine scientists' participation patterns in conferences and compare our model with data from six conferences across various scientific fields and communities. Our model shows that the probability for a scientist to participate in a given conference series strongly depends on the balance between the number of participations and non-participations during his/her early connections with the community. An active participation in a conference series strengthens the scientist's association with that particular conference community and thus increases the probability of future participations.
Theoretical model for mesoscopic-level scale-free self-organization of functional brain networks.
Piersa, Jaroslaw; Piekniewski, Filip; Schreiber, Tomasz
2010-11-01
In this paper, we provide theoretical and numerical analysis of a geometric activity flow network model which is aimed at explaining mathematically the scale-free functional graph self-organization phenomena emerging in complex nervous systems at a mesoscale level. In our model, each unit corresponds to a large number of neurons and may be roughly seen as abstracting the functional behavior exhibited by a single voxel under functional magnetic resonance imaging (fMRI). In the course of the dynamics, the units exchange portions of formal charge, which correspond to waves of activity in the underlying microscale neuronal circuit. The geometric model abstracts away the neuronal complexity and is mathematically tractable, which allows us to establish explicit results on its ground states and the resulting charge transfer graph modeling functional graph of the network. We show that, for a wide choice of parameters and geometrical setups, our model yields a scale-free functional connectivity with the exponent approaching 2, which is in agreement with previous empirical studies based on fMRI. The level of universality of the presented theory allows us to claim that the model does shed light on mesoscale functional self-organization phenomena of the nervous system, even without resorting to closer details of brain connectivity geometry which often remain unknown. The material presented here significantly extends our previous work where a simplified mean-field model in a similar spirit was constructed, ignoring the underlying network geometry.
Mutarelli, Rita de Cassia; Lima, Ana Cecilia de Souza; Sabundjian, Gaiane, E-mail: rmutarelli@gmail.com, E-mail: aclima@ipen.br, E-mail: gdjian@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)
2015-07-01
Social responsibility has been one of the great discussions in institutional management, and that is an important variable in the strategy and performance of the institutions. The Instituto de Pesquisas Energeticas e Nucleares (IPEN) has worked for the development of environmental and social issues, converging mainly to the benefit of the population. The theory that guides the social responsibility practices is always difficult to measure for several reasons. One reason for this difficulty is that social responsibility involves a variety of issues that are converted in rights, obligations and expectations of different audiences that could be internal and external to the organization. In addition, the different understanding of the institutions about social and environmental issues is another source of complexity. Based on the study context including: the topic being researched, the chosen institute and the questions resulting from the research, the aim of this paper is to propose a theoretical model to describe and analyze the social responsibility of IPEN. The main contribution of this study is to develop a model that integrates the dimensions of social responsibility. These dimensions - also called constructs - are composed of indexes and indicators that were previously used in various contexts of empirical research, combined with the theoretical and conceptual review of social responsibility. The construction of the proposed theoretical model was based on the research of various methodologies and various indicators for measuring social responsibility. This model was statistically tested, analyzed, adjusted, and the end result is a consistent model to measure the perceived value of social responsibility of IPEN. This work could also be applied to other institutions. Moreover, it may be improved and become a tool that will serve as a thermometer to measure social and environmental issues, and will support decision making in various management processes. (author)
Presenting a Theoretical Model of Four Conceptions of Civic Education
Cohen, Aviv
2010-01-01
This conceptual study will question the ways different epistemological conceptions of citizenship and education influence the characteristics of civic education. While offering a new theoretical framework, the different undercurrent conceptions that lay at the base of the civic education process shall be brought forth. With the use of the method…
Determining Student Competency in Field Placements: An Emerging Theoretical Model
Twyla L. Salm
2016-06-01
Full Text Available This paper describes a qualitative case study that explores how twenty-three field advisors, representing three human service professions including education, nursing, and social work, experience the process of assessment with students who are struggling to meet minimum competencies in field placements. Five themes emerged from the analysis of qualitative interviews. The field advisors primary concern was the level of professional competency achieved by practicum students. Related to competency were themes concerned with the field advisor's role in being accountable and protecting the reputation of his/her profession as well as the reputation of the professional program affiliated with the practicum student's professional education. The final theme – teacher-student relationship –emerged from the data, both as a stand-alone and global or umbrella theme. As an umbrella theme, teacher-student relationship permeated each of the other themes as the participants interpreted their experiences of the process of assessment through the mentor relationships. A theoretical model was derived from these findings and the description of the model is presented. Cet article décrit une étude de cas qualitative qui explore comment vingt-trois conseillers de stages, représentant trois professions de services sociaux comprenant l’éducation, les soins infirmiers et le travail social, ont vécu l’expérience du processus d’évaluation avec des étudiants qui ont des difficultés à acquérir les compétences minimales durant les stages. Cinq thèmes ont été identifiés lors de l’analyse des entrevues qualitatives. La préoccupation principale des conseillers de stages était le niveau de compétence professionnelle acquis par les stagiaires. Les thèmes liés à la compétence étaient le rôle des conseillers de stages dans leur responsabilité pour protéger la réputation de leur profession ainsi que la réputation d’un programme professionnel
Rodríguez, J; Clemente, G; Sanjuán, N; Bon, J
2014-01-01
The drying kinetics of thyme was analyzed by considering different conditions: air temperature of between 40°C and 70°C , and air velocity of 1 m/s. A theoretical diffusion model and eight different empirical models were fitted to the experimental data. From the theoretical model application, the effective diffusivity per unit area of the thyme was estimated (between 3.68 × 10(-5) and 2.12 × 10 (-4) s(-1)). The temperature dependence of the effective diffusivity was described by the Arrhenius relationship with activation energy of 49.42 kJ/mol. Eight different empirical models were fitted to the experimental data. Additionally, the dependence of the parameters of each model on the drying temperature was determined, obtaining equations that allow estimating the evolution of the moisture content at any temperature in the established range. Furthermore, artificial neural networks were developed and compared with the theoretical and empirical models using the percentage of the relative errors and the explained variance. The artificial neural networks were found to be more accurate predictors of moisture evolution with VAR ≥ 99.3% and ER ≤ 8.7%.
Surge motion of an ice floe in waves: comparison of theoretical and experimental models
Meylan, Michael; Bennetts, Luke; French, Benjamin; Thomas, Giles
2014-01-01
A theoretical model and an experimental model of surge motions of an ice floe due to regular waves are presented. The theoretical model is a modified version of Morrison's equation, valid for small floating bodies. The experimental model is implemented in a wave basin at scale 1:100, using a thin plastic disk to model the floe. The processed experimental data displays a regime change in surge amplitude when the incident wavelength is approximately twice the floe diameter. It is shown that the theoretical model is accurate in the large wavelength regime, but highly inaccurate for the small wavelength regime.
Theoretical models of ferromagnetic III-V semiconductors
Jungwirth, T.; Sinova, Jairo; Kučera, J.; MacDonald, A. H.
2002-01-01
Recent materials research has advanced the maximum ferromagnetic transition temperature in semiconductors containing magnetic elements toward room temperature. Reaching this goal would make information technology applications of these materials likely. In this article we briefly review the status of work over the past five years which has attempted to achieve a theoretical understanding of these complex magnetic systems. The basic microscopic origins of ferromagnetism in the (III,Mn)V compoun...
Theoretical modeling of orientational effects in liquid-crystal layers
Melnikova, E. A.
2005-11-01
In the work the approximate analytical relations describing the director distribution in depth of a plane-parallel layer of nematic liquid crystal are presented. The analytical expression determining the orientational effect of the periodic surface in a system "relief grating - liquid crystal" is derived. Its diffraction characteristics are studied theoretically. Relaxation kinetics of the director in a plane-parallel layer of nematic liquid crystal is considered taking account of the microscopic inertia moment.
Theoretical model of gravitational perturbation of current collector axisymmetric flow field
Walker, John S.; Brown, Samuel H.; Sondergaard, Neal A.
1990-05-01
Some designs of liquid-metal current collectors in homopolar motors and generators are essentially rotating liquid-metal fluids in cylindrical channels with free surfaces and will, at critical rotational speeds, become unstable. An investigation at David Taylor Research Center is being performed to understand the role of gravity in modifying this ejection instability. Some gravitational effects can be theoretically treated by perturbation techniques on the axisymmetric base flow of the liquid metal. This leads to a modification of previously calculated critical-current-collector ejection values neglecting gravity effects. The purpose of this paper is to document the derivation of the mathematical model which determines the perturbation of the liquid-metal base flow due to gravitational effects. Since gravity is a small force compared with the centrifugal effects, the base flow solutions can be expanded in inverse powers of the Froude number and modified liquid-flow profiles can be determined as a function of the azimuthal angle. This model will be used in later work to theoretically study the effects of gravity on the ejection point of the current collector.
Theoretical model for cellular shapes driven by protrusive and adhesive forces.
Doron Kabaso
2011-05-01
Full Text Available The forces that arise from the actin cytoskeleton play a crucial role in determining the cell shape. These include protrusive forces due to actin polymerization and adhesion to the external matrix. We present here a theoretical model for the cellular shapes resulting from the feedback between the membrane shape and the forces acting on the membrane, mediated by curvature-sensitive membrane complexes of a convex shape. In previous theoretical studies we have investigated the regimes of linear instability where spontaneous formation of cellular protrusions is initiated. Here we calculate the evolution of a two dimensional cell contour beyond the linear regime and determine the final steady-state shapes arising within the model. We find that shapes driven by adhesion or by actin polymerization (lamellipodia have very different morphologies, as observed in cells. Furthermore, we find that as the strength of the protrusive forces diminish, the system approaches a stabilization of a periodic pattern of protrusions. This result can provide an explanation for a number of puzzling experimental observations regarding cellular shape dependence on the properties of the extra-cellular matrix.
Theoretical models to predict the mechanical behavior of thick composite tubes
Volnei Tita
2012-02-01
Full Text Available This paper shows theoretical models (analytical formulations to predict the mechanical behavior of thick composite tubes and how some parameters can influence this behavior. Thus, firstly, it was developed the analytical formulations for a pressurized tube made of composite material with a single thick ply and only one lamination angle. For this case, the stress distribution and the displacement fields are investigated as function of different lamination angles and reinforcement volume fractions. The results obtained by the theoretical model are physic consistent and coherent with the literature information. After that, the previous formulations are extended in order to predict the mechanical behavior of a thick laminated tube. Both analytical formulations are implemented as a computational tool via Matlab code. The results obtained by the computational tool are compared to the finite element analyses, and the stress distribution is considered coherent. Moreover, the engineering computational tool is used to perform failure analysis, using different types of failure criteria, which identifies the damaged ply and the mode of failure.
Weller, Daniel; Shiwakoti, Suvash; Bergholz, Peter; Grohn, Yrjo; Wiedmann, Martin
2015-01-01
Technological advancements, particularly in the field of geographic information systems (GIS), have made it possible to predict the likelihood of foodborne pathogen contamination in produce production environments using geospatial models. Yet, few studies have examined the validity and robustness of such models. This study was performed to test and refine the rules associated with a previously developed geospatial model that predicts the prevalence of Listeria monocytogenes in produce farms in New York State (NYS). Produce fields for each of four enrolled produce farms were categorized into areas of high or low predicted L. monocytogenes prevalence using rules based on a field's available water storage (AWS) and its proximity to water, impervious cover, and pastures. Drag swabs (n = 1,056) were collected from plots assigned to each risk category. Logistic regression, which tested the ability of each rule to accurately predict the prevalence of L. monocytogenes, validated the rules based on water and pasture. Samples collected near water (odds ratio [OR], 3.0) and pasture (OR, 2.9) showed a significantly increased likelihood of L. monocytogenes isolation compared to that for samples collected far from water and pasture. Generalized linear mixed models identified additional land cover factors associated with an increased likelihood of L. monocytogenes isolation, such as proximity to wetlands. These findings validated a subset of previously developed rules that predict L. monocytogenes prevalence in produce production environments. This suggests that GIS and geospatial models can be used to accurately predict L. monocytogenes prevalence on farms and can be used prospectively to minimize the risk of preharvest contamination of produce. PMID:26590280
Andersen, Karsten Brandt; Levinsen, Simon; Svendsen, Winnie Edith;
2009-01-01
In this article we present a generalized theoretical model for the continuous separation of particles using the pinched flow fractionation method. So far the theoretical models have not been able to predict the separation of particles without the use of correction factors. In this article we pres...
Dziedziewicz, Dorota; Karwowski, Maciej
2015-01-01
This paper presents a new theoretical model of creative imagination and its applications in early education. The model sees creative imagination as composed of three inter-related components: vividness of images, their originality, and the level of transformation of imageries. We explore the theoretical and practical consequences of this new…
Theoretical and practical aspects of modelling activated sludge processes
Meijer, S.C.F.
2004-01-01
This thesis describes the full-scale validation and calibration of a integrated metabolic activated sludge model for biological phosphorus removal. In chapters 1 and 2 the metabolic model is described, in chapters 3 to 6 the model is tested and in chapters 7 and 8 the model is put into practice.
Theoretical and practical aspects of modelling activated sludge processes
Meijer, S.C.F.
2004-01-01
This thesis describes the full-scale validation and calibration of a integrated metabolic activated sludge model for biological phosphorus removal. In chapters 1 and 2 the metabolic model is described, in chapters 3 to 6 the model is tested and in chapters 7 and 8 the model is put into practice. Cha
Theoretical and practical aspects of modelling activated sludge processes
Meijer, S.C.F.
2004-01-01
This thesis describes the full-scale validation and calibration of a integrated metabolic activated sludge model for biological phosphorus removal. In chapters 1 and 2 the metabolic model is described, in chapters 3 to 6 the model is tested and in chapters 7 and 8 the model is put into practice. Cha
1979-01-01
to motivate the form of the results for inelastic binary collisions characterized by an isotropic scattering cross section. For an inelastic...which are excited or ionized by the e -beam . Strictly speaking , the reverse process for reaction (101. 1) should also be included, although its...ETC F/S 20/5 THEORETICAL MODELING OF MOLECULAR AND ELECTRON KINETIC PROCESS~— efl ~ (rj)JAN 79 W B LACINA NO OO i~—78—C—Ofl9UNCLASSIFIED NRTC—79—7R
Game Theoretic Modeling of Water Resources Allocation Under Hydro-Climatic Uncertainty
Brown, C.; Lall, U.; Siegfried, T.
2005-12-01
Typical hydrologic and economic modeling approaches rely on assumptions of climate stationarity and economic conditions of ideal markets and rational decision-makers. In this study, we incorporate hydroclimatic variability with a game theoretic approach to simulate and evaluate common water allocation paradigms. Game Theory may be particularly appropriate for modeling water allocation decisions. First, a game theoretic approach allows economic analysis in situations where price theory doesn't apply, which is typically the case in water resources where markets are thin, players are few, and rules of exchange are highly constrained by legal or cultural traditions. Previous studies confirm that game theory is applicable to water resources decision problems, yet applications and modeling based on these principles is only rarely observed in the literature. Second, there are numerous existing theoretical and empirical studies of specific games and human behavior that may be applied in the development of predictive water allocation models. With this framework, one can evaluate alternative orderings and rules regarding the fraction of available water that one is allowed to appropriate. Specific attributes of the players involved in water resources management complicate the determination of solutions to game theory models. While an analytical approach will be useful for providing general insights, the variety of preference structures of individual players in a realistic water scenario will likely require a simulation approach. We propose a simulation approach incorporating the rationality, self-interest and equilibrium concepts of game theory with an agent-based modeling framework that allows the distinct properties of each player to be expressed and allows the performance of the system to manifest the integrative effect of these factors. Underlying this framework, we apply a realistic representation of spatio-temporal hydrologic variability and incorporate the impact of
L^2-theoretical study of the relation between the LIBOR market model and the HJM model
Yasuoka, Takashi
2013-01-01
In previous works, the author introduced metric spaces of term structure models to study the relation between the LIBOR market model and the HJM model. However that framework is not comprehensive, nor does it admit an extendable structure. This paper introduces a new metric space to better develop the perspective argument. A metric space is naturally constructed on the set of bond price processes such that the space allows many types of term structure models. This metric presents a general vi...
Theoretical Explanation and Improvement to the Flare Model of Lithography Based on the Kirk Test
CHEN De-Liang; CAO Yi-Ping; HUANG Zhen-Fen
2011-01-01
@@ The Kirk test has good precision for measuring stray light in optical lithography and is the usual method of measuring stray light.However, Kirk did not provide a theoretical explanation to his simulation model.We attempt to give Kirk's model a kind of theoretical explanation and a little improvement based on the model of point spread function of scattering and the theory of statistical optics.It is indicated by simulation that the improved model fits Kirk's measurement data better.
Kim, Young Rae
2013-01-01
A theoretical model of metacognition in complex modeling activities has been developed based on existing frameworks, by synthesizing the re-conceptualization of metacognition at multiple levels by looking at the three sources that trigger metacognition. Using the theoretical model as a framework, this study was designed to explore how students'…
Deferred Action: Theoretical model of process architecture design for emergent business processes
Patel, N.V.
2007-01-01
Full Text Available E-Business modelling and ebusiness systems development assumes fixed company resources, structures, and business processes. Empirical and theoretical evidence suggests that company resources and structures are emergent rather than fixed. Planning business activity in emergent contexts requires flexible ebusiness models based on better management theories and models . This paper builds and proposes a theoretical model of ebusiness systems capable of catering for emergent factors that affect business processes. Drawing on development of theories of the ‘action and design’class the Theory of Deferred Action is invoked as the base theory for the theoretical model. A theoretical model of flexible process architecture is presented by identifying its core components and their relationships, and then illustrated with exemplar flexible process architectures capable of responding to emergent factors. Managerial implications of the model are considered and the model’s generic applicability is discussed.
Ledermann, Thomas; Kenny, David A
2012-02-01
Studying dyads, very often there is a theoretical construct that has an effect on both members, such as relationship harmony or shared environment. To model such influences, the common fate model (CFM) is often the most appropriate approach. In this article, we address conceptual and statistical issues in the use of the standard CFM and present a series of variations, all of which are estimated by structural equation modeling (SEM). For indistinguishable dyad members (e.g., gay couples), we describe the use of a multilevel SEM method. Throughout the paper, we draw connections to the actor-partner interdependence model (APIM). We also discuss the analysis of hybrid models that combines both the CFM and the APIM. The models are illustrated using data from heterosexual couples.
Nick J Klein
2013-03-01
Full Text Available In order to identify the biogeochemical parameters controlling pCO2, total chlorophyll a, and dimethylsulfide (DMS concentrations during the North East Atlantic Spring Bloom (NASB, we used previously unpublished particulate and dissolved elemental concentrations to construct several linear regression models; first by hypothesis-testing, and then with exhaustive stepwise linear regression followed by leave-one-out cross-validation. The field data was obtained along a latitudinal transect from the Azores Islands to the North Atlantic, and best-fit models (determined by lowest predictive error of up to three variables are presented. Total chlorophyll a is predicted best by biomass (POC, PON parameters and by pigments characteristic of picophytoplankton for the southern section of the sampling transect (from the Azores to the Rockhall-Hatton Plateau and coccolithophores in the northern portion (from the Rockhall-Hatton Plateau to the Denmark Strait. Both the pCO2 and DMS models included variables traditionally associated with the development of the NASB such as mixed-layer depth and with Fe, Si and P-deplete conditions (dissolved Fe, dissolved and biogenic silica, dissolved PO43-. However, the regressions for pCO2 and DMS also include intracellular V and Mo concentrations, respectively. Mo is involved in DMS production as a cofactor in dimethylsulfoxide reductase. No significant biological role for V has yet been determined, although intracellular V is significantly correlated (p-value < 0.05 with biogenic silica (R2 = 0.72 and total chlorophyll a (R2 = 0.49 while the same is not true for its biogeochemical analogue Mo, suggesting active uptake of V by phytoplankton. Our statistical analysis suggests these two lesser-studied metals may play more important roles in bloom dynamics than previously thought, and highlights a need for studies focused on determining their potential biological requirements and cell quotas.
Theoretical model for a Faraday anomalous dispersion optical filter
Yin, B.; Shay, T. M.
1991-01-01
A model for the Faraday anomalous dispersion optical filter is presented. The model predicts a bandwidth of 0.6 GHz and a transmission peak of 0.98 for a filter operating on the Cs (D2) line. The model includes hyperfine effects and is valid for arbitrary magnetic fields.
M$^2$I Communication: From Theoretical Modeling to Practical Design
Guo, Hongzhi
2015-01-01
Wireless communications in complex environments are constrained by lossy media and complicated structures. Magnetic Induction (MI) has been proved to be an efficient solution to extend the communication range. Due to the small coil antenna's physical limitation, however, MI's communication range is still very limited. To this end, Metamaterial-enhanced Magnetic Induction (M$^2$I) communication has been proposed and the theoretical results suggest that it can significantly increase the communication performance, namely, data rate and communication range. Nevertheless, currently, the real implementation of M$^2$I is still a challenge and there is no guideline on design and fabrication of spherical metamaterial. In this paper, we propose a practical design by using a spherical coil array to realize M$^2$I and we prove that it can achieve negative permeability and there exists a resonance condition where the radiated magnetic field can be significantly amplified. The radiation and communication performance are ev...
Theoretical models for NO decomposition in Cu-exchanged zeolites
Tsekov, R
2015-01-01
A unified description of the catalytic effect of Cu-exchanged zeolites is proposed for the decomposition of NO. A general expression for the rate constant of NO decomposition is obtained by assuming that the rate-determining step consists of the transferring of a single atom associated with breaking of the N-O bond. The analysis is performed on the base of the generalized Langevin equation and takes into account both the potential interactions in the system and the memory effects due to the zeolite vibrations. Two different mechanisms corresponding to monomolecular and bimolecular NO decomposition are discussed. The catalytic effect in the monomolecular mechanism is related to both the Cu+ ions and zeolite O-vacancies, while in the case of the bimolecular mechanism the zeolite contributes through dissipation only. The comparison of the theoretically calculated rate constants with experimental results reveals additional information about the geometric and energetic characteristics of the active centers and con...
A graph theoretical perspective of a drug abuse epidemic model
Nyabadza, F.; Mukwembi, S.; Rodrigues, B. G.
2011-05-01
A drug use epidemic can be represented by a finite number of states and transition rules that govern the dynamics of drug use in each discrete time step. This paper investigates the spread of drug use in a community where some users are in treatment and others are not in treatment, citing South Africa as an example. In our analysis, we consider the neighbourhood prevalence of each individual, i.e., the proportion of the individual’s drug user contacts who are not in treatment amongst all of his or her contacts. We introduce parameters α∗, β∗ and γ∗, depending on the neighbourhood prevalence, which govern the spread of drug use. We examine how changes in α∗, β∗ and γ∗ affect the system dynamics. Simulations presented support the theoretical results.
The theoretical foundations for size spectrum models of fish communities
Andersen, Ken Haste; Jacobsen, Nis Sand; Farnsworth, K.D.
2016-01-01
assessment of fisheries. We describe the fundamental concepts in size-based models about food encounter and the bioenergetics budget of individuals. Within the general framework three model types have emerged that differs in their degree of complexity: the food-web, the trait-based and the community model....... We demonstrate the differences between the models through examples of their response to fishing and their dynamic behavior. We review implementations of size spectrum models and describe important variations concerning the functional response, whether growth is food-dependent or fixed...
Theoretical and experimental modeling of a rail gun accelerator
Zheleznyj, V. B.; Zagorskij, A. V.; Katsnel'Son, S. S.; Kudryavtsev, A. V.; Plekhanov, A. V.
1993-04-01
Results of a series of experiments in the acceleration of macrobodies are analyzed using an integral model of a current arc and a quasi-1D magnetic gasdynamic model. The integral model uses gasdynamic equations averaged by the size of a plasma pump and equations based on the second Kirchhoff's law for electrical current. The quasi-1D model is based on 1D magnetic gasdynamic equations for mean values of density, pressure, velocity, and internal power. Electromagnetic parameters are determined from Maxwell integral equations. It is concluded that the proposed models take into account the major mechanisms of momentum loss and are capable of adequately describing electromagnetic rail accelerators.
Using Graph and Vertex Entropy to Compare Empirical Graphs with Theoretical Graph Models
Tomasz Kajdanowicz
2016-09-01
Full Text Available Over the years, several theoretical graph generation models have been proposed. Among the most prominent are: the Erdős–Renyi random graph model, Watts–Strogatz small world model, Albert–Barabási preferential attachment model, Price citation model, and many more. Often, researchers working with real-world data are interested in understanding the generative phenomena underlying their empirical graphs. They want to know which of the theoretical graph generation models would most probably generate a particular empirical graph. In other words, they expect some similarity assessment between the empirical graph and graphs artificially created from theoretical graph generation models. Usually, in order to assess the similarity of two graphs, centrality measure distributions are compared. For a theoretical graph model this means comparing the empirical graph to a single realization of a theoretical graph model, where the realization is generated from the given model using an arbitrary set of parameters. The similarity between centrality measure distributions can be measured using standard statistical tests, e.g., the Kolmogorov–Smirnov test of distances between cumulative distributions. However, this approach is both error-prone and leads to incorrect conclusions, as we show in our experiments. Therefore, we propose a new method for graph comparison and type classification by comparing the entropies of centrality measure distributions (degree centrality, betweenness centrality, closeness centrality. We demonstrate that our approach can help assign the empirical graph to the most similar theoretical model using a simple unsupervised learning method.
The transtheoretical model and substance dependence: theoretical and practical aspects
2009-01-01
OBJECTIVE: This paper aims to present and discuss the Transtheoretical Model and its importance for the treatment of substance abuse disorders. METHOD: A literature review was made based on articles from the last 10 years in substance use with human subjects found in PubMed (Medline) and the Scientific Electronic Library Online, as well as on the main books written by the creators of the model. From the initial collection of articles related to the Transtheoretical Model, the University of Rh...
Jones, Ant
2015-01-01
The construction of viable and physically-realistic interstellar dust models is only possible if the constraints imposed by laboratory data on interstellar dust analogue materials are respected and used within a meaningful theoretical framework. These physical dust models can then be directly compared to observations without the need for any tuning to fit the observations. Such models will generally fail to achieve the excellent fits to observations that empirical models are able to achieve. However, the physically-realistic approach will necessarily lead to a deeper insight and a fuller understanding of the nature and evolution of interstellar dust. The THEMIS modelling approach, based on (hydrogenated) amorphous carbons and amorphous silicates with metallic Fe and/or FeS nano-inclusions appears to be a promising move in this direction.
Theoretical modeling of sliding vane compressor with leakage
Al-Hawaj, Osama [Department of Mechanical Engineering, University of Kuwait, P.O. Box 5969, Safat 13060 (Kuwait)
2009-11-15
Performance of a sliding vane compressor is significantly influenced by the leakage effect occurring between adjacent cells during the compression phase of the cycle. In this paper, thermodynamic and dynamical mathematical models were formulated for a double action sliding vane compressor including leakage effect modeling. The leakage modeling is incorporated through an analytic pressure model with a single tunable parameter to be adjusted to correspond with specific compressor leakage characteristics. The effect of leakage on the cell pressure, temperature, mass, and work, and total vane torque variations were qualitatively investigated. The study illustrated the significant effect of leakage on power input requirement, discharge pressure and mass delivery, and less significant effect on mechanical efficiency and specific mass delivery. The validity of the simulation results is made by comparing the pressure work calculated from both the thermodynamic and the dynamic models. (author)
Anticipation in stuttering: A theoretical model of the nature of stutter prediction.
Garcia-Barrera, Mauricio A; Davidow, Jason H
2015-06-01
The fact that some people who stutter have the ability to anticipate a stuttering moment is essential for several theories of stuttering and important for maximum effectiveness of many currently used treatment techniques. The "anticipation effect," however, is poorly understood despite much investigation into this phenomenon. In the present paper, we combine (1) behavioral evidence from the stuttering-anticipation literature, (2) speech production models, and (3) models of error detection to propose a theoretical model of anticipation. Integrating evidence from theories such as Damasio's Somatic Marker Hypothesis, Levelt's Perceptual Monitoring Theory, Guenther's The Directions Into Velocities of Articulators (DIVA) model, Postma's Covert Repair Hypothesis, among others, our central thesis is that the anticipation of a stuttering moment occurs as an outcome of the interactions between previous learning experiences (i.e., learnt associations between stuttered utterances and any self-experienced or environmental consequence) and error monitoring. Possible neurological mechanisms involved in generating conscious anticipation are also discussed, along with directions for future research. The reader will be able to: (a) describe historical theories that explain how PWS may learn to anticipate stuttering; (b) state some traditional sources of evidence of anticipation in stuttering; (c) describe how PWS may be sensitive to the detection of a stuttering; (d) state some of the neural correlates that may underlie anticipation in stuttering; and (e) describe some of the possible utilities of incorporating anticipation into stuttering interventions. Copyright © 2015 Elsevier Inc. All rights reserved.
A theoretical model for calculation of the detective quantum efficiency in granular scintillators
Cavouras, D. E-mail: cavouras@hol.gr; Kandarakis, I.; Tsoukos, S.; Kateris, A.; Nomicos, C.D.; Panayiotakis, G.S
2001-11-01
A theoretical model has been developed for calculating the detective quantum efficiency (DQE) of scintillators, by taking into account the internal structure of granular scintillators often used in medical imaging detectors. Scintillators were considered to consist of N elementary thin layers containing spherical scintillating grains of equal size. Grains were assumed to be regularly distributed within each thin layer, the thickness of the latter being equal to the grain diameter. Values of the X-ray absorption and X-ray attenuation coefficients, of the intrinsic X-ray to light conversion efficiency and of the optical scattering and absorption coefficients were used as input data to the model. Optical scattering and optical absorption coefficients were determined by fitting the model to experimental luminescence data. The model was employed to calculate the detective quantum efficiency of La{sub 2}O{sub 2}S:Tb, Y{sub 2}O{sub 2}S:Tb, Y{sub 2}O{sub 2}S:Eu, ZnSCdS:Ag, ZnSCdS:Au,Cu scintillators. Results of the calculations were found close to values published in previous studies.
Experimental observations and theoretical models for beam-beam phenomena
Kheifets, S.
1981-03-01
The beam-beam interaction in storage rings exhibits all the characteristics of nonintegrable dynamical systems. Here one finds all kinds of resonances, closed orbits, stable and unstable fixed points, stochastic layers, chaotic behavior, diffusion, etc. The storage ring itself being an expensive device nevertheless while constructed and put into operation presents a good opportunity of experimentally studying the long-time behavior of both conservative (proton machines) and nonconservative (electron machines) dynamical systems - the number of bunch-bunch interactions routinely reaches values of 10/sup 10/-10/sup 11/ and could be increased by decreasing the beam current. At the same time the beam-beam interaction puts practical limits for the yield of the storage ring. This phenomenon not only determines the design value of main storage ring parameters (luminosity, space charge parameters, beam current), but also in fact prevents many of the existing storage rings from achieving design parameters. Hence, the problem has great practical importance along with its enormous theoretical interest. A brief overview of the problem is presented.
Behavioral models as theoretical frames to analyze the business objective
Hernán Alonso Bafico
2015-12-01
Full Text Available This paper examines Pfeffer’s Models of Behavior and connects each of them with attributes of the definition of the firm’s objective, assumed as the maximization of the sustainable, long term valor of the residual claims.Each of the five models of behavior (rational, social, moral, retrospective and cognitive contributes to the decision making and goal setting processes with its particular and complementary elements. From those assuming complete rationality and frictionless markets, to the models emphasizing the role of ethical positions, and the presence of perceptive and cognitive mechanisms. The analysis highlights the main contributions of critical theories and models of behavior, underlining their focus on non-traditional variables, regarded as critical inputs for goal setting processes and designing alternative executive incentive schemes. The explicit consideration of those variables does not indicate the need for a new definition of corporate objective. The maximization of the long term value of the shareholders’ claims still defines the relevant objective function of the firm, remaining as the main yardstick of corporate performance.Behavioral models are recognized as important tools to help managers direct their attention to long term strategies. In the last part, we comment on the relationship between the objective function and behavioral models, from the practitioners’ perspective.Key words: Firm Objectives, Behavioral Models, Value Maximization, Stakeholder Theory.
Rigorous theoretical derivation of lumped models to transmission line systems
Zhao Jixiang
2012-01-01
By virtue of the negative electric parameter concept,i.e.negative lumped resistance,inductance,conductance and capacitance (N-RLGC),the lumped equivalent models of transmission line systems,including the circuit model,two-port π-network and T-network,are given.We start from the N-segment-ladder-like equivalent networks composed distributed parameters,and achieve the input impedance in the form of a continued fraction.Utilizing the continued fraction theory,the expressions of input impedance are obtained under three kinds of extreme cases,i.e.the load impedances are equal to zero,infinity and characteristic impedance,respectively.When the number of segment N is limited to infinity,they are transformed to lumped elements.Comparison between the distributed model and lumped model of transmission lines,the expression of tanh yd,which is the key term in the transmission line equations,are obtained by RLGC,furthermore,according to input admittance,admittance matrix and ABCD matrix of transmission lines,the lumped equivalent circuit models,π-networks and T-networks have been given.The models are verified in the frequency and time domain,respectively,showing that the models are accurate and efficient.
Pathways in coal thermolysis: a theoretical and experimental study with model compounds
Ekpenyong, I.A.; Virk, P.S.
1982-01-01
Fundamental aspects of coal thermolysis were investigated, including how the chemical structures of aromatics, hydroaromatics, and alcohols affect their reactivities as hydrogen donors and acceptors in coal processing. The susceptibilities of substructural entities in coals to fragmentation via a number of thermal pericyclic and free radical mechanisms were probed, as were the factors governing relative reactivities within series of such coal model compounds. The theoretical part of the work applied perturbation molecular orbital (PMO) and frontier orbital theories, in conjunction with ..pi..- and pseudo-..pi.. MO's, to the study of model compound reactivity. This enabled prediction of reactivity patterns of H-donors, H-acceptors and coal-like structures as functions of their ..pi..- and sigma-bond configurations, including heteroatomic effects. Experimentally, the liquid phase reactions of the coal model compound PhOCH/sub 2/Ph (Benzyl phenyl ether, BPE) were detailed for the first time in each of four hydronaphthalene H-donor solvents in the temperature range 220/sup 0/ to 300/sup 0/C. The thermolysis of BPE exhibited a pronounced dependence on solvent structure, both with respect to product selectivities and reaction kinetics. BPE thermolysis pathways were delineated as involving (a) rearrangement, leading to isomerization, (b) hydrogenations, leading ultimately to PhOH and PhCH/sub 3/ products, and (c) addition reactions, engendering heavy products. Pathways (b) and (c) are competitive and, in each, self-reactions of BPE-derivatives vie against reactions between these and the donor solvent. Of the detailed free radical and pericyclic reaction mechanisms postulated, the latter rationalized many more facets of the BPE results than the former. The theoretical and experimental results were appraised against previous coal thermolysis literature.
Transdiagnostic models of anxiety disorder: Theoretical and empirical underpinnings.
Norton, Peter J; Paulus, Daniel J
2017-08-01
Despite the increasing development, evaluation, and adoption of transdiagnostic cognitive behavioral therapies, relatively little has been written to detail the conceptual and empirical psychopathology framework underlying transdiagnostic models of anxiety and related disorders. In this review, the diagnostic, genetic, neurobiological, developmental, behavioral, cognitive, and interventional data underlying the model are described, with an emphasis on highlighting elements that both support and contradict transdiagnostic conceptualizations. Finally, a transdiagnostic model of anxiety disorder is presented and key areas of future evaluation and refinement are discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.
Jones, Matt; Love, Bradley C
2011-08-01
that have plagued previous theoretical movements.
Membrane Phospholipid Redistribution in Cytokinesis: A Theoretical Model
Mei-Wen AN; Wen-Zhou WU; Wei-Yi CHEN
2005-01-01
In cell mitosis, cytokinesis is a major deformation process, during which the site of the contractile ring is determined by the biochemical stimulus from asters of the mitotic apparatus, actin and myosin assembly is related to the motion of membrane phospholipids, and local distribution and arrangement of the microfilament cytoskeleton are different at different cytokinesis stages. Based on the Zinemanas-Nir model, a new model is proposed in this study to simulate the entire process by coupling the biochemical stimulus with the mechanical actions. There were three assumptions in this model: the movements of phospholipid proteins are driven by gradients of biochemical stimulus on the membrane surface; the local assembly of actin and myosin filament depends on the amount of phospholipid proteins at the same location;and the surface tension includes membrane tensions due to both the passive deformation of the membrane and the active contraction of actin filament, which is determined by microfilament redistribution and rearrangement. This model could explain the dynamic movement of microfilaments during cytokinesis and predict cell deformation. The calculated results from this model demonstrated that the reorientation of phospholipid proteins and the redistribution and reorientation of microfilaments may play a crucial role in cell division. This model may better represent the cytokinesis process by the introduction of biochemical stimulus.
Theoretic models for recommendation and implementation of assistive technology
Ana Cristina de Jesus Alves
2016-07-01
Full Text Available Introduction: The latest international researches seek to understand the factors affecting the successful use of assistive technology devices through studies regarding the assessments systematizing; abandonment of devices; or theoric models that consider the aspects of those devices implementation. In Brazil the researches are focused on developing new technologies and there are still not sufficient studies related to the successful use of devices and ways of assistive technology implementation. Objective: To identify conceptual models used for indication and implementation of assistive technology devices. Method: Literature review. The survey was conducted in six databases: CINAHAL, Eric, GALE, LILACS, MEDLINE e PsycInfo. A critical analysis described by Grant and Booth was used. Results: There are no records of a Brazilian survey and among 29 selected articles, 17 conceptual models used in the area of AT were found; of these, 14 were specific to AT. The results showed that the new conceptual models of TA are under development and the conceptual model “Matching Person and Technology – MPT” was the most mentioned. Conclusion: We can observe that the practices related to TA area in international context shows a correlation with conceptual models, thus, we hope this study might have the capacity to contribute for the propagation of this precepts at national level
Design theoretic analysis of three system modeling frameworks.
McDonald, Michael James
2007-05-01
This paper analyzes three simulation architectures from the context of modeling scalability to address System of System (SoS) and Complex System problems. The paper first provides an overview of the SoS problem domain and reviews past work in analyzing model and general system complexity issues. It then identifies and explores the issues of vertical and horizontal integration as well as coupling and hierarchical decomposition as the system characteristics and metrics against which the tools are evaluated. In addition, it applies Nam Suh's Axiomatic Design theory as a construct for understanding coupling and its relationship to system feasibility. Next it describes the application of MATLAB, Swarm, and Umbra (three modeling and simulation approaches) to modeling swarms of Unmanned Flying Vehicle (UAV) agents in relation to the chosen characteristics and metrics. Finally, it draws general conclusions for analyzing model architectures that go beyond those analyzed. In particular, it identifies decomposition along phenomena of interaction and modular system composition as enabling features for modeling large heterogeneous complex systems.
Determinants of Business Success – Theoretical Model and Empirical Verification
Kozielski Robert
2016-12-01
Full Text Available Market knowledge, market orientation, learning competencies, and a business performance were the key issues of the research project conducted in the 2006 study. The main findings identified significant relationships between the independent variables (market knowledge, market orientation, learning competencies and the dependent variables (business success. A partial correlation analysis indicated that a business success primarily relies on organisational learning competencies. Organisational learning competencies, to a large extent (almost 60%, may be explained by the level of corporate market knowledge and market orientation. The aim of the paper is to evaluate to what extent the relationships between the variables are still valid. The research was based on primary and secondary data sources. The major field of the research was carried out in the form of quantitative studies. The results of the 2014 study are consistent with the previous (2006 results.
Priyanka eSingh
2011-03-01
Full Text Available We have taken advantage of a newly described Drosophila model to gain insights into the potential mechanism of antiepileptic drugs (AEDs, a group of drugs that are widely used in the treatment of several neurological and psychiatric conditions besides epilepsy. In the recently described Drosophila model that is inspired by pentylenetetrazole (PTZ induced kindling epileptogenesis in rodents, chronic PTZ treatment for seven days causes a decreased climbing speed and an altered CNS transcriptome, with the latter mimicking gene expression alterations reported in epileptogenesis. In the model, an increased climbing speed is further observed seven days after withdrawal from chronic PTZ. We used this post-PTZ withdrawal regime to identify potential AED mechanism. In this regime, treatment with each of the five AEDs tested, namely, ethosuximide (ETH, gabapentin (GBP, vigabatrin (VGB, sodium valproate (NaVP and levetiracetam (LEV, resulted in rescuing of the altered climbing behavior. The AEDs also normalized PTZ withdrawal induced transcriptomic perturbation in fly heads; whereas AED untreated flies showed a large number of up- and down-regulated genes which were enriched in several processes including gene expression and cell communication, the AED treated flies showed differential expression of only a small number of genes that did not enrich gene expression and cell communication processes. Gene expression and cell communication related upregulated genes in AED untreated flies overrepresented several pathways - spliceosome, RNA degradation, and ribosome in the former category, and inositol phosphate metabolism, phosphatidylinositol signaling, endocytosis and hedgehog signaling in the latter. Transcriptome remodeling effect of AEDs was overall confirmed by microarray clustering that clearly separated the profiles of AED treated and untreated flies. Besides being consistent with previously implicated pathways, our results provide evidence for a role of
Theoretical model for ultracold molecule formation via adaptive feedback control
Poschinger, U; Wester, R; Weidemüller, M; Koch, C P; Kosloff, R; Poschinger, Ulrich; Salzmann, Wenzel; Wester, Roland; Weidemueller, Matthias; Koch, Christiane P.; Kosloff, Ronnie
2006-01-01
We investigate pump-dump photoassociation of ultracold molecules with amplitude- and phase-modulated femtosecond laser pulses. For this purpose a perturbative model for the light-matter interaction is developed and combined with a genetic algorithm for adaptive feedback control of the laser pulse shapes. The model is applied to the formation of 85Rb2 molecules in a magneto-optical trap. We find for optimized pulse shapes an improvement for the formation of ground state molecules by more than a factor of 10 compared to unshaped pulses at the same pump-dump delay time, and by 40% compared to unshaped pulses at the respective optimal pump-dump delay time. Since our model yields directly the spectral amplitudes and phases of the optimized pulses, the results are directly applicable in pulse shaping experiments.
A control theoretic model of driver steering behavior
Donges, E.
1977-01-01
A quantitative description of driver steering behavior such as a mathematical model is presented. The steering task is divided into two levels: (1) the guidance level involving the perception of the instantaneous and future course of the forcing function provided by the forward view of the road, and the response to it in an anticipatory open-loop control mode; (2) the stabilization level whereby any occuring deviations from the forcing function are compensated for in a closed-loop control mode. This concept of the duality of the driver's steering activity led to a newly developed two-level model of driver steering behavior. Its parameters are identified on the basis of data measured in driving simulator experiments. The parameter estimates of both levels of the model show significant dependence on the experimental situation which can be characterized by variables such as vehicle speed and desired path curvature.
Gonzálvez, Alicia G; González Ureña, Ángel
2012-10-01
A laser spectroscopic technique is described that combines transmission and resonance-enhanced Raman inelastic scattering together with low laser power (view, a model for the Raman signal dependence on the sample thickness is also presented. Essentially, the model considers the sample to be homogeneous and describes the underlying physics using only three parameters: the Raman cross-section, the laser-radiation attenuation cross-section, and the Raman signal attenuation cross-section. The model was applied successfully to describe the sample-size dependence of the Raman signal in both β-carotene standards and carrot roots. The present technique could be useful for direct, fast, and nondestructive investigations in food quality control and analytical or physiological studies of animal and human tissues.
Turbulent convection model in the overshooting region: II. Theoretical analysis
Zhang, S Q
2012-01-01
Turbulent convection models are thought to be good tools to deal with the convective overshooting in the stellar interior. However, they are too complex to be applied in calculations of stellar structure and evolution. In order to understand the physical processes of the convective overshooting and to simplify the application of turbulent convection models, a semi-analytic solution is necessary. We obtain the approximate solution and asymptotic solution of the turbulent convection model in the overshooting region, and find some important properties of the convective overshooting: I. The overshooting region can be partitioned into three parts: a thin region just outside the convective boundary with high efficiency of turbulent heat transfer, a power law dissipation region of turbulent kinetic energy in the middle, and a thermal dissipation area with rapidly decreasing turbulent kinetic energy. The decaying indices of the turbulent correlations $k$, $\\bar{u_{r}'T'}$, and $\\bar{T'T'}$ are only determined by the ...
Verifying a theoretical model of loads on an asymmetric disk
Krauze, K.
1985-02-01
The results are evaluated of testing a single asymmetric disk cutter used for coal cutting under operational conditions in an underground mine. The tests were aimed at verifying a mathematical model of coal cutting. The mean conventional pressure, a term used by the author, was determined. Forces acting on an asymmetric cutting disk calculated by mathematical modeling were compared to those determined in the tests. Comparisons showed that the model accurately describes coal cutting: in the case of tangential force error was not higher than 18%, in the case of lateral force it was not higher than 46% and in the case of compression force it was not higher than 15%. The method for calculating loads on an asymmetric disk cutter was characterized by reduced labor consumption and low number of tests. 1 reference.
Impression Formation and Modifiability: Testing a Theoretical Model
Mrug, Sylvie; Hoza, Betsy
2007-01-01
This study proposed and tested a developmental model of impression formation based on observed behavior, prior expectancies, and additional incongruent information. Participants were 51 kindergartners, 53 second graders, and 104 college students who provided trait and liking judgments after watching a child actor engage in behaviors from three…
Voronoi Cell Patterns: theoretical model and application to submonolayer growth
González, Diego Luis; Einstein, T. L.
2012-02-01
We use a simple fragmentation model to describe the statistical behavior of the Voronoi cell patterns generated by a homogeneous and isotropic set of points in 1D and in 2D. In particular, we are interested in the distribution of sizes of these Voronoi cells. Our model is completely defined by two probability distributions in 1D and again in 2D, the probability to add a new point inside an existing cell and the probability that this new point is at a particular position relative to the preexisting point inside this cell. In 1D the first distribution depends on a single parameter while the second distribution is defined through a fragmentation kernel; in 2D both distributions depend on a single parameter. The fragmentation kernel and the control parameters are closely related to the physical properties of the specific system under study. We apply our model to describe the Voronoi cell patterns of island nucleation for critical island sizes i=0,1,2,3. Experimental results for the Voronoi cells of InAs/GaAs quantum dots are also described by our model.
Photoabsorption spectrum of helium trimer cation—Theoretical modeling
Kalus, René [Centre of Excellence IT4Innovations and Department of Applied Mathematics, VSB-Technical University of Ostrava, 17. listopadu 15, 708 33 Ostrava (Czech Republic); Karlický, František [Regional Centre of Advanced Technologies and Materials and Department of Physical Chemistry, Faculty of Science, Palacký University, Tř. 17. listopadu 12, 771 46 Olomouc (Czech Republic); Lepetit, Bruno [Laboratoire Collisions Agrégats Réactivité, IRSAMC and UMR5589 du CNRS, Université de Toulouse, UPS, 118 route de Narbonne, 31062 Toulouse Cedex (France); Paidarová, Ivana [J. Heyrovský Institute of Physical Chemistry, ASCR, v.v.i., Dolejškova 3, 182 23 Praha (Czech Republic); Gadea, Florent Xavier [Laboratoire de Chimie et de Physique Quantiques, IRSAMC and UMR5626 du CNRS, Université de Toulouse, UPS, 118 route de Narbonne, 31062 Toulouse Cedex (France)
2013-11-28
The photoabsorption spectrum of He{sub 3}{sup +} is calculated for two semiempirical models of intracluster interactions and compared with available experimental data reported in the middle UV range [H. Haberland and B. von Issendorff, J. Chem. Phys. 102, 8773 (1995)]. Nuclear delocalization effects are investigated via several approaches comprising quantum samplings using either exact or approximate (harmonic) nuclear wavefunctions, as well as classical samplings based on the Monte Carlo methodology. Good agreement with the experiment is achieved for the model by Knowles et al., [Mol. Phys. 85, 243 (1995); Mol. Phys. 87, 827 (1996)] whereas the model by Calvo et al., [J. Chem. Phys. 135, 124308 (2011)] exhibits non-negligible deviations from the experiment. Predictions of far UV absorption spectrum of He{sub 3}{sup +}, for which no experimental data are presently available, are reported for both models and compared to each other as well as to the photoabsorption spectrum of He{sub 2}{sup +}. A simple semiempirical point-charge approximation for calculating transition probabilities is shown to perform well for He{sub 3}{sup +}.
Model United Nations and Deep Learning: Theoretical and Professional Learning
Engel, Susan; Pallas, Josh; Lambert, Sarah
2017-01-01
This article demonstrates that the purposeful subject design, incorporating a Model United Nations (MUN), facilitated deep learning and professional skills attainment in the field of International Relations. Deep learning was promoted in subject design by linking learning objectives to Anderson and Krathwohl's (2001) four levels of knowledge or…
Theoretical biology: Comparing models of species abundance - Brief Communications Arising
Chave, J.; Alonso, D.; Etienne, R.S.
2006-01-01
Ecologists are struggling to explain how so many tropical tree species can coexist in tropical forests, and several empirical studies have demonstrated that negative density dependence is an important mechanism of tree-species coexistence1, 2. Volkov et al.3 compare a model incorporating negative de
Theoretical Modeling of Mechanical Behavior and Release Properties of Microcapsules
Sagis, L.M.C.
2015-01-01
Microcapsules in food often have a shell with a complex microstructure; the mechanical and structural properties of these shells affect the response of the capsules to deforming forces and the release kinetics of encapsulated components. In this chapter we will discuss a number of models which are t
Chan, R W; Titze, I R
2000-01-01
The viscoelastic shear properties of human vocal fold mucosa (cover) were previously measured as a function of frequency [Chan and Titze, J. Acoust. Soc. Am. 106, 2008-2021 (1999)], but data were obtained only in a frequency range of 0.01-15 Hz, an order of magnitude below typical frequencies of vocal fold oscillation (on the order of 100 Hz). This study represents an attempt to extrapolate the data to higher frequencies based on two viscoelastic theories, (1) a quasilinear viscoelastic theory widely used for the constitutive modeling of the viscoelastic properties of biological tissues [Fung, Biomechanics (Springer-Verlag, New York, 1993), pp. 277-292], and (2) a molecular (statistical network) theory commonly used for the rheological modeling of polymeric materials [Zhu et al., J. Biomech. 24, 1007-1018 (1991)]. Analytical expressions of elastic and viscous shear moduli, dynamic viscosity, and damping ratio based on the two theories with specific model parameters were applied to curve-fit the empirical data. Results showed that the theoretical predictions matched the empirical data reasonably well, allowing for parametric descriptions of the data and their extrapolations to frequencies of phonation.
Wettability of graphitic-carbon and silicon surfaces: MD modeling and theoretical analysis
Ramos-Alvarado, Bladimir; Kumar, Satish; Peterson, G. P.
2015-07-01
The wettability of graphitic carbon and silicon surfaces was numerically and theoretically investigated. A multi-response method has been developed for the analysis of conventional molecular dynamics (MD) simulations of droplets wettability. The contact angle and indicators of the quality of the computations are tracked as a function of the data sets analyzed over time. This method of analysis allows accurate calculations of the contact angle obtained from the MD simulations. Analytical models were also developed for the calculation of the work of adhesion using the mean-field theory, accounting for the interfacial entropy changes. A calibration method is proposed to provide better predictions of the respective contact angles under different solid-liquid interaction potentials. Estimations of the binding energy between a water monomer and graphite match those previously reported. In addition, a breakdown in the relationship between the binding energy and the contact angle was observed. The macroscopic contact angles obtained from the MD simulations were found to match those predicted by the mean-field model for graphite under different wettability conditions, as well as the contact angles of Si(100) and Si(111) surfaces. Finally, an assessment of the effect of the Lennard-Jones cutoff radius was conducted to provide guidelines for future comparisons between numerical simulations and analytical models of wettability.
Shrigley, Robert L.
This study was based on Hovland's four-part statement, Who says what to whom with what effect, the rationale for persuasive communication, a theoretical model for modifying attitudes. Part I was a survey of 139 perservice elementary teachers from which were generated the more credible characteristics of metric instructors, a central element in the who component of Hovland's model. They were: (1) background in mathematics and science, (2) fluency in metrics, (3) capability of thinking metrically, (4) a record of excellent teaching, (5) previous teaching of metric measurement to children, (6) responsibility for teaching metric content in methods courses and (7) an open enthusiasm for metric conversion. Part II was a survey of 45 mathematics educators where belief statements were synthesized for the what component of Hovland's model. It found that math educators support metric measurement because: (1) it is consistent with our monetary system; (2) the conversion of units is easier into metric than English; (3) it is easier to teach and easier to learn than English measurement; there is less need for common fractions; (4) most nations use metric measurement; scientists have used it for decades; (5) American industry has begun to use it; (6) metric measurement will facilitate world trade and communication; and (7) American children will need it as adults; educational agencies are mandating it. With the who and what of Hovland's four-part statement defined, educational researchers now have baseline data to use in testing experimentally the effect of persuasive communication on the attitude of preservice teachers toward metrication.
Accelerator simulation and theoretical modelling of radiation effects (SMoRE)
2018-01-01
This publication summarizes the findings and conclusions of the IAEA coordinated research project (CRP) on accelerator simulation and theoretical modelling of radiation effects, aimed at supporting Member States in the development of advanced radiation-resistant structural materials for implementation in innovative nuclear systems. This aim can be achieved through enhancement of both experimental neutron-emulation capabilities of ion accelerators and improvement of the predictive efficiency of theoretical models and computer codes. This dual approach is challenging but necessary, because outputs of accelerator simulation experiments need adequate theoretical interpretation, and theoretical models and codes need high dose experimental data for their verification. Both ion irradiation investigations and computer modelling have been the specific subjects of the CRP, and the results of these studies are presented in this publication which also includes state-ofthe- art reviews of four major aspects of the project...
Rabosky, Daniel L; Mitchell, Jonathan S; Chang, Jonathan
2017-07-01
Bayesian analysis of macroevolutionary mixtures (BAMM) is a statistical framework that uses reversible jump Markov chain Monte Carlo to infer complex macroevolutionary dynamics of diversification and phenotypic evolution on phylogenetic trees. A recent article by Moore et al. (MEA) reported a number of theoretical and practical concerns with BAMM. Major claims from MEA are that (i) BAMM's likelihood function is incorrect, because it does not account for unobserved rate shifts; (ii) the posterior distribution on the number of rate shifts is overly sensitive to the prior; and (iii) diversification rate estimates from BAMM are unreliable. Here, we show that these and other conclusions from MEA are generally incorrect or unjustified. We first demonstrate that MEA's numerical assessment of the BAMM likelihood is compromised by their use of an invalid likelihood function. We then show that "unobserved rate shifts" appear to be irrelevant for biologically plausible parameterizations of the diversification process. We find that the purportedly extreme prior sensitivity reported by MEA cannot be replicated with standard usage of BAMM v2.5, or with any other version when conventional Bayesian model selection is performed. Finally, we demonstrate that BAMM performs very well at estimating diversification rate variation across the ${\\sim}$20% of simulated trees in MEA's data set for which it is theoretically possible to infer rate shifts with confidence. Due to ascertainment bias, the remaining 80% of their purportedly variable-rate phylogenies are statistically indistinguishable from those produced by a constant-rate birth-death process and were thus poorly suited for the summary statistics used in their performance assessment. We demonstrate that inferences about diversification rates have been accurate and consistent across all major previous releases of the BAMM software. We recognize an acute need to address the theoretical foundations of rate-shift models for
Motility of a model bristle-bot: A theoretical analysis
Cicconofri, Giancarlo; DeSimone, Antonio
2015-11-01
Bristle-bots are legged robots that can be easily made out of a toothbrush head and a small vibrating engine. Despite their simple appearance, the mechanism enabling them to propel themselves by exploiting friction with the substrate is far from trivial. Numerical experiments on a model bristle-bot have been able to reproduce such a mechanism revealing, in addition, the ability to switch direction of motion by varying the vibration frequency. This paper provides a detailed account of these phenomena through a fully analytical treatment of the model. The equations of motion are solved through an expansion in terms of a properly chosen small parameter. The convergence of the expansion is rigorously proven. In addition, the analysis delivers formulas for the average velocity of the robot and for the frequency at which the direction switch takes place. A quantitative description of the mechanism for the friction modulation underlying the motility of the bristle-bot is also provided.
Coordination-theoretic approach to modelling grid service composition process
Meng Qian; Zhong Liu; Jing Wang; Li Yao; Weiming Zhang
2010-01-01
A grid service composite process is made up of complex coordinative activities.Developing the appropriate model of grid service coordinative activities is an important foundation for the grid service composition.According to the coordination theory,this paper elaborates the process of the grid service composition by using UML 2.0,and proposes an approach to modelling the grid service composition process based on the coordination theory.This approach helps not only to analyze accurately the task activities and relevant dependencies among task activities,but also to facilitate the adaptability of the grid service orchestration to further realize the connectivity,timeliness,appropriateness and expansibility of the grid service composition.
Model-theoretical foundation of action and progression
田启家; 史忠植
1997-01-01
Action is one of the most important concepts in computer science, and situation calculus is the standard formalism for representing and reasoning about actions and their effects. Situation calculus essentially could be presented in a logic framework. Based on the framework LR, such a logic framework is given. Minimal action theory is proposed and studied from the point of view of model theory. By theorems of mathematical logic, some results about the definability about the progression in minimal action theory are obtained.
Hybrid empirical--theoretical approach to modeling uranium adsorption
Hull, Larry C.; Grossman, Christopher; Fjeld, Robert A.; Coates, John T.; Elzerman, Alan W
2004-05-01
An estimated 330 metric tons of U are buried in the radioactive waste Subsurface Disposal Area (SDA) at the Idaho National Engineering and Environmental Laboratory (INEEL). An assessment of U transport parameters is being performed to decrease the uncertainty in risk and dose predictions derived from computer simulations of U fate and transport to the underlying Snake River Plain Aquifer. Uranium adsorption isotherms were measured for 14 sediment samples collected from sedimentary interbeds underlying the SDA. The adsorption data were fit with a Freundlich isotherm. The Freundlich n parameter is statistically identical for all 14 sediment samples and the Freundlich K{sub f} parameter is correlated to sediment surface area (r{sup 2}=0.80). These findings suggest an efficient approach to material characterization and implementation of a spatially variable reactive transport model that requires only the measurement of sediment surface area. To expand the potential applicability of the measured isotherms, a model is derived from the empirical observations by incorporating concepts from surface complexation theory to account for the effects of solution chemistry. The resulting model is then used to predict the range of adsorption conditions to be expected in the vadose zone at the SDA based on the range in measured pore water chemistry. Adsorption in the deep vadose zone is predicted to be stronger than in near-surface sediments because the total dissolved carbonate decreases with depth.
A THEORETICAL MODEL OF SOCIO-PSYCHOLOGICAL SUPPORT WORK PROCESSES FOR MANAGEMENT OF PRODUCTION TEAM
Tatyana Gennadevna Pronyushkina
2015-01-01
This article discusses the management of production team, in particular the developed theoretical model of socio-psychological support work processes for management of production team. The author of the research are formulated the purpose and objectives of social-psychological work on management of the production team. Developed in the study a theoretical model aimed at determining the conditions and the identification of features of effective management of the enterprise taking into account ...
GSTARS computer models and their applications, part I: theoretical development
无
2008-01-01
GSTARS is a series of computer models developed by the U.S. Bureau of Reclamation for alluvial river and reservoir sedimentation studies while the authors were employed by that agency. The first version of GSTARS was released in 1986 using Fortran IV for mainframe computers. GSTARS 2.0 was released in 1998 for personal computer application with most of the code in the original GSTARS revised, improved, and expanded using Fortran IV/77. GSTARS 2.1 is an improved and revised GSTARS 2.0 with graphical user interface. The unique features of all GSTARS models are the conjunctive use of the stream tube concept and of the minimum stream power theory. The application of minimum stream power theory allows the determination of optimum channel geometry with variable channel width and cross-sectional shape. The use of the stream tube concept enables the simulation of river hydraulics using one-dimensional numerical solutions to obtain a semi-two-dimensional presentation of the hydraulic conditions along and across an alluvial channel. According to the stream tube concept, no water or sediment particles can cross the walls of stream tubes, which is valid for many natural rivers. At and near sharp bends, however, sediment particles may cross the boundaries of stream tubes. GSTARS3, based on FORTRAN 90/95, addresses this phenomenon and further expands the capabilities of GSTARS 2.1 for cohesive and non-cohesive sediment transport in rivers and reservoirs. This paper presents the concepts, methods, and techniques used to develop the GSTARS series of computer models, especially GSTARS3.
Graph theoretical analysis of the energy landscape of model polymers.
Baiesi, Marco; Bongini, Lorenzo; Casetti, Lapo; Tattini, Lorenzo
2009-07-01
In systems characterized by a rough potential-energy landscape, local energetic minima and saddles define a network of metastable states whose topology strongly influences the dynamics. Changes in temperature, causing the merging and splitting of metastable states, have nontrivial effects on such networks and must be taken into account. We do this by means of a recently proposed renormalization procedure. This method is applied to analyze the topology of the network of metastable states for different polypeptidic sequences in a minimalistic polymer model. A smaller spectral dimension emerges as a hallmark of stability of the global energy minimum and highlights a nonobvious link between dynamic and thermodynamic properties.
Theoretical model of a piezoelectric composite spinal fusion interbody implant.
Tobaben, Nicholas E; Domann, John P; Arnold, Paul M; Friis, Elizabeth A
2014-04-01
Failure rates of spinal fusion are high in smokers and diabetics. The authors are investigating the development of a piezoelectric composite biomaterial and interbody device design that could generate clinically relevant levels of electrical stimulation to help improve the rate of fusion for these patients. A lumped parameter model of the piezoelectric composite implant was developed based on a model that has been utilized to successfully predict power generation for piezoceramics. Seven variables (fiber material, matrix material, fiber volume fraction, fiber aspect ratio, implant cross-sectional area, implant thickness, and electrical load resistance) were parametrically analyzed to determine their effects on power generation within reasonable implant constraints. Influences of implant geometry and fiber aspect ratio were independent of material parameters. For a cyclic force of constant magnitude, implant thickness was directly and cross-sectional area inversely proportional to power generation potential. Fiber aspect ratios above 30 yielded maximum power generation potential while volume fractions above 15% showed superior performance. This investigation demonstrates the feasibility of using composite piezoelectric biomaterials in medical implants to generate therapeutic levels of direct current electrical stimulation. The piezoelectric spinal fusion interbody implant shows promise for helping increase success rates of spinal fusion.
A theoretical design for learning model addressing the networked society
Levinsen, Karin; Nielsen, Janni; Sørensen, Birgitte Holm
2010-01-01
is continuously decreasing. We teach for deep learning but are confronted by students' cost-benefit strategies when they navigate through the study programme under time pressure. To meet these challenges a Design for Learning Model has been developed. The aim is to provide a scaffold that ensures students......The transition from the industrial to the networked society produces contradictions that challenges the educational system and force it to adapt to new conditions. In a Danish virtual Master in Information and Communication Technologies and Learning (MIL) these contradictions appear as a field...... of tension between time resources and the demand for educational quality. Our approach is based on constructivist and social constructivist traditions but we are required to measure students according to a list of learning goals. The size of curriculum is growing while the time available for learning...
Theoretical models for polarimetric microwave remote sensing of earth terrain
Borgeaud, M.; Nghiem, S. V.; Shin, R. T.; Kong, J. A.
1989-01-01
Using the two-layer anisotropic random medium, a mathematically rigorous, fully polarimetric model is developed to compute the Mueller and covariance matrices in the backscattering direction for various kinds of earth terrain. The electric field is first written in the form of an integral equation involving the unperturbed dyadic Green's function in the absence of the permittivity fluctuations. The integral equation is then solved by an iterative series known as the Born series. With only the first term of the series, which physically describes a single scattering process, the fully polarimetric backscattering coefficients are derived. Four different kinds of upgoing and downgoing waves exist due to the excitation of both ordinary and extraordinary waves in the anisotropic random medium. An averaging scheme over the azimuthal direction is used to simulate the effects on the radar backscattering due to the azimuthal randomness in the growth direction of leaves in tree and grass fields.
Theoretical model for assessing properties of local structures in metalloprotein
Koyimatu, M.; Shimahara, H.; Iwayama, M.; Sugimori, K.; Kawaguchi, K.; Saito, H.; Nagao, H.
2013-02-01
For model structures containing two aromatic rings such as the indole of Trp5 and the imidazole of His64 in human carbonic anhydrase (hCAII), the location and orientation of the rings with regard to each other contribute to the magnitude of the entire interaction energy. Here the energetic contribution of the indole ring of Trp5 on the imidazole ring of the "out" conformation of His64 were calculated to compare with that of the alternative "in" conformation of His64 by using the MP2/6-311++G(d,p)//B3LYP/6-31G(d,p) method. We suggest that 1) Trp5 and the "out" conformation of His64 are predicted to form a stack of planar parallel rings via π-stacking interaction and 2) the energy is 1.73-1.83 kcal/mol to stabilize the "out" conformation, compared with the "in" conformation.
Theoretical models for fluid thermodynamics based on the quasi-Gaussian entropy theory
Amadei, Andrea
1998-01-01
Summary The theoretical modeling of fluid thermodynamics is one of the most challenging fields in physical chemistry. In fact the fluid behavior, except at very low density conditions, is still extremely difficult to be modeled from a statistical mechanical point of view, as for any realistic model
Lise, W.; Linderhof, V.G.M.; Kuik, O.; Kemfert, C.; Ostling, R.; Heinzow, T.
2006-01-01
This paper develops a static computational game theoretic model. Illustrative results for the liberalising European electricity market are given to demonstrate the type of economic and environmental results that can be generated with the model. The model is empirically calibrated to eight
Lise, W.; Linderhof, V.G.M.; Kuik, O.; Kemfert, C.; Ostling, R.; Heinzow, T.
2006-01-01
This paper develops a static computational game theoretic model. Illustrative results for the liberalising European electricity market are given to demonstrate the type of economic and environmental results that can be generated with the model. The model is empirically calibrated to eight Northweste
THEORETICAL FLOW MODEL THROUGH A CENTRIFUGAL PUMP USED FOR WATER SUPPLY IN AGRICULTURE IRRIGATION
SCHEAUA Fanel Dorel
2017-05-01
motion of the rotor. A theoretical model for calculating the flow of the working fluid through the interior of a centrifugal pump model is presented in this paper as well as the numerical analysis on the virtual model performed with the ANSYS CFX software in order to highlight the flow parameters and flow path-lines that are formed during centrifugal pump operation.
Theoretical model of the helium zone plate microscope
Salvador Palau, Adrià; Bracco, Gianangelo; Holst, Bodil
2017-01-01
Neutral helium microscopy is a new technique currently under development. Its advantages are the low energy, charge neutrality, and inertness of the helium atoms, a potential large depth of field, and the fact that at thermal energies the helium atoms do not penetrate into any solid material. This opens the possibility, among others, for the creation of an instrument that can measure surface topology on the nanoscale, even on surfaces with high aspect ratios. One of the most promising designs for helium microscopy is the zone plate microscope. It consists of a supersonic expansion helium beam collimated by an aperture (skimmer) focused by a Fresnel zone plate onto a sample. The resolution is determined by the focal spot size, which depends on the size of the skimmer, the optics of the system, and the velocity spread of the beam through the chromatic aberrations of the zone plate. An important factor for the optics of the zone plate is the width of the outermost zone, corresponding to the smallest opening in the zone plate. The width of the outermost zone is fabrication limited to around 10 nm with present-day state-of-the-art technology. Due to the high ionization potential of neutral helium atoms, it is difficult to build efficient helium detectors. Therefore, it is crucial to optimize the microscope design to maximize the intensity for a given resolution and width of the outermost zone. Here we present an optimization model for the helium zone plate microscope. Assuming constant resolution and width of the outermost zone, we are able to reduce the problem to a two-variable problem (zone plate radius and object distance) and we show that for a given beam temperature and pressure, there is always a single intensity maximum. We compare our model with the highest-resolution zone plate focusing images published and show that the intensity can be increased seven times. Reducing the width of the outermost zone to 10 nm leads to an increase in intensity of more than 8000
Dubois, Frédérique; Giraldeau, Luc-Alain; Hamilton, Ian M; Grant, James W A; Lefebvre, Louis
2004-08-01
Hawk-dove games have been extensively used to predict the conditions under which group-living animals should defend their resources against potential usurpers. Typically, game-theoretic models on aggression consider that resource defense may entail energetic and injury costs. However, intruders may also take advantage of owners who are busy fighting to sneak access to unguarded resources, imposing thereby an additional cost on the use of the escalated hawk strategy. In this article we modify the two-strategy hawk-dove game into a three-strategy hawk-dove-sneaker game that incorporates a distraction-sneaking tactic, allowing us to explore its consequences on the expected level of aggression within groups. Our model predicts a lower proportion of hawks and hence lower frequencies of aggressive interactions within groups than do previous two-strategy hawk-dove games. The extent to which distraction sneakers decrease the frequency of aggression within groups, however, depends on whether they search only for opportunities to join resources uncovered by other group members or for both unchallenged resources and opportunities to usurp.
T3 and cardiac myocyte cell: a theoretical model.
Athanasios, Tsatsaris; Antonios, Baldoukas; Antonios, Loumousiotis; Eustathios, Koukounaris; Maria, Giota; Despina, Perrea
2013-08-01
In the last decades, the outstanding role of Thyroid gland in regulating both physiological and pathological operation of cardiovascular system has been acknowledged worldwide. Three main domains of Thyroid function, that is to say, euthyroidism -hyperthyroidism-hypothyroidism, have a direct impact on cardiac response through a variety of mechanisms. Cellular pathways mediate in cardiac contractility, cardiac output, cardiac rhythm, arterial blood pressure and peripheral vessel resistance. Particular biochemical algorithms exist not only between Thyroid hormones' serum concentration and thyroid gland but also between the hormones' serum level and heart muscle genes. These biochemical pathways primarily regulate the appropriate secretion of levothyroxine (T4) and triiodothyronine(T3) via Thyroid- Stimulating-Hormone(TSH) pituitary system, and secondly adjust the cardiac function. In this study, a mathematic model has been developed describing significant aspects of positive or negative feedback mechanisms of THYRO-CARDIAC (THY-CAR) system along with potential applications of novel up-to-date patents in this area of research.
Jesper Sjolte
2014-09-01
Full Text Available The relation between δ 18O of precipitation and temperature has been used in numerous studies to reconstruct past temperatures at ice core sites in Greenland and Antarctica. During the past two decades, it has become clear that the slope between δ 18O and temperature varies in both space and time. Here, we use a general circulation model driven by changes in orbital parameters to investigate the Greenland δ 18O–temperature relation for the previous interglacial, the Eemian. In our analysis, we focus on changes in the moisture source regions, and the results underline the importance of taking the seasonality of climate change into account. The orbitally driven experiments show that continental evaporation over North America increases during summer in the warm parts of the Eemian, while marine evaporation decreases. This likely flattens the Greenland δ 18O response to temperature during summer. Since the main climate change in the experiments occurs during summer this adds to a limited response of δ 18O, which is more strongly tied to temperature during winter than during summer. A south–west to north–east gradient in the δ 18O–temperature slope is also evident for Greenland, with low slopes in the south–west and steeper slopes in the north–east. This probably reflects the proportion of continental moisture and Arctic moisture arriving in Greenland, with more continental moisture in the south–west and less in the north–east, and vice versa for the Arctic moisture.
A beginner's guide to writing the nursing conceptual model-based theoretical rationale.
Gigliotti, Eileen; Manister, Nancy N
2012-10-01
Writing the theoretical rationale for a study can be a daunting prospect for novice researchers. Nursing's conceptual models provide excellent frameworks for placement of study variables, but moving from the very abstract concepts of the nursing model to the less abstract concepts of the study variables is difficult. Similar to the five-paragraph essay used by writing teachers to assist beginning writers to construct a logical thesis, the authors of this column present guidelines that beginners can follow to construct their theoretical rationale. This guide can be used with any nursing conceptual model but Neuman's model was chosen here as the exemplar.
Fsusy and Field Theoretical Construction
Sedra, M B
2009-01-01
Following our previous work on fractional spin symmetries (FSS) \\cite{6, 7}, we consider here the construction of field theoretical models that are invariant under the $D=2(1/3,1/3)$ supersymmetric algebra.
Mantsinen, M. [Helsinki Univ. of Technology, Espoo (Finland). Dept. of Technical Physics
1999-06-01
toroidal momentum. For a trapped ion, this leads to a change in its radial position. If toroidally asymmetric ICRF waves are used, the resulting spatial drift of the trapped ions is either inwards or outwards depending on the direction of the launched ICRF wave. ICRF heating experiments with different ICRF antenna phasings at JET give first experimental evidence for the presence of this ICRF-induced pinch. Significant differences are observed when the ICRF waves are launched in opposite toroidal directions. Analysis of the experiments with a three-dimensional orbit-averaged Monte Carlo code shows that the observations are consistent with theory. A technique for fast numerical evaluation of the wave-particle interaction in such a code has been developed and implemented. In general, good agreement between the simulations and experimental results has been obtained, which indicates that the present theoretical picture of ICRF heating is consistent with experiments. This gives confidence in simulations of other experiments and in the modelling ICRF heating schemes for future reactor plasmas. However, certain limitations have been identified in the present modelling of mode conversion and high-power ICRF heating in low-density plasmas, which require further investigation. (orig.) 75 refs. The thesis includes also six previous publications by author
Theoretical mean-variance relationship of IP network traffic based on ON/OFF model
JIN Yi; ZHOU Gang; JIANG DongChen; YUAN Shuai; WANG LiLi; CAO JianTing
2009-01-01
Mean-variance relationship (MVR), nowadays agreed in power law form, is an important function. It Is currently used by traffic matrix estimation as a basic statistical assumption. Because all the existing papers obtain MVR only through empirical ways, they cannot provide theoretical support to power law MVR or the definition of its power exponent. Furthermore, because of the lack of theoretical model, all traffic matrix estimation methods based on MVR have not been theoretically supported yet. By observ-ing both our laboratory and campus network for more than one year, we find that such an empirical MVR is not sufficient to describe actual network traffic. In this paper, we derive a theoretical MVR from ON/OFF model. Then we prove that current empirical power law MVR is generally reasonable by the fact that it is an approximate form of theoretical MVR under specific precondition, which can theoretically support those traffic matrix estimation algorithms of using MVR. Through verifying our MVR by actual observation and public DECPKT traces, we verify that our theoretical MVR Is valid and more capable of describing actual network traffic than power law MVR.
A retroductive theoretical model of the pathway to chemical dependency in nurses.
Burns, C M
1998-02-01
Much of the research on chemical dependency in nurses over the past 25 years has been a-theoretical and has tended to focus on descriptive characteristics of nurses. This field of study lacks systematic knowledge building and a useful theoretical base. This article focuses on the development of a middle range theory that begins to explicate the transactions of the chemically dependent nurse with the environment and the process through which nurses become addicted. Steiner's theory models approach using retroductive inference was the method selected to develop the theory. Theoretical work from Bandura, Jessor, and Pender were used as source theories to develop the middle range theory presented.
2010-07-01
... installing stationary SI ICE produced in the previous model year? 60.4236 Section 60.4236 Protection of... installing stationary SI ICE produced in the previous model year? (a) After July 1, 2010, owners and operators may not install stationary SI ICE with a maximum engine power of less than 500 HP that do not...
Bugaev, Edgar; Petkov, Valery
2007-01-01
Possibilities of an experimental search for gamma-ray bursts from primordial black hole (PBH) evaporations in space are reconsidered. It is argued that the corresponding constraints which can be obtained in experiments with cosmic ray detectors strongly depend on theoretical approach used for a description of the PBH evaporation process. Predictions of several theoretical models for gamma-ray spectra from final stages of PBH life (integrated over time) are given.
THEORETICAL-MODEL FOR THE SCATTERING OF LIGHT BY DENTIN AND COMPARISON WITH MEASUREMENTS
ZIJP, [No Value; TENBOSCH, JJ
1993-01-01
A theoretical model of the scattering of light by dentin is presented. The model that results is a superposition of several scattering contributions, i.e., scattering by mineral crystals, collagen fibrils, and dentinal tubules. These tubules are oriented so that they cause an asymmetrical scattering
Achievement Goals and Discrete Achievement Emotions: A Theoretical Model and Prospective Test
Pekrun, Reinhard; Elliot, Andrew J.; Maier, Markus A.
2006-01-01
A theoretical model linking achievement goals to discrete achievement emotions is proposed. The model posits relations between the goals of the trichotomous achievement goal framework and 8 commonly experienced achievement emotions organized in a 2 (activity/outcome focus) x 2 (positive/negative valence) taxonomy. Two prospective studies tested…
By-product mutualism and the ambiguous effects of harsher environments - A game-theoretic model
De Jaegher, Kris; Hoyer, Britta
2016-01-01
We construct two-player two-strategy game-theoretic models of by-product mutualism, where our focus lies on the way in which the probability of cooperation among players is affected by the degree of adversity facing the players. In our first model, cooperation consists of the production of a public
A theoretical model of film condensation in a bundle of horizontal low finned tubes
Honda, H.; Nozu, S.; Takeda, Y. (Okayama Univ. (Japan))
1989-05-01
The previous theoretical model of film condensation on a single horizontal low finned tube is extended to include the effect of condensate inundation. Based on the flow characteristics of condensate on a vertical column of horizontal low finned tubes, two major flow modes, the column mode and the sheet mode, are considered. In the column mode, the surface of the lower tubes is divided into the portion under the condensate column where the condensate flow is affected by the impinging condensate from the upper tubes, and the portion between the condensate columns where the condensate flow is not affected by the impinging condensate. In the sheet mode, the whole tube surface is assumed to be affected by the impinging condensate. Sample calculations for practical conditions show that the effects of the fin spacing and the number of vertical tube rows on the heat transfer performance is significant for R-12, while the effects are small for steam. The predicted value of the heat transfer coefficient for each tube row compares well with available experimental data, including four fluids and five tube bundles.
A new theoretical model of the quasistatic single-fiber pullout problem: Analysis of stress field
Qing, Hai
2013-01-01
results of the stress distributions, in both fully bonded region and fully debonded region, are presented for a typical glass/epoxy composite system with different fibre volume fraction and model length. In fully bonded region, the theoretical results from present model are more accurate compared......A new theoretical model is developed in order to predict the stress transfer during the quasistatic single-fibre pullout process. The theoretical approach retains all relevant stress and strain components, and satisfies exactly the interfacial continuity conditions and all the stress boundary...... conditions. For both matrix and fibre, the equilibrium equations along radial direction are satisfied strictly, while the equilibrium equations along axial direction are satisfied in the integral forms. Three normal stress-strain relationships are strictly satisfied, while the radial displacement gradient...
Theoretical Models of Light Scattering Applied in Sizing Particles in Coal Water Slurry
王仁哲; 张荣曾; 徐志强
2004-01-01
Advantges and disadvantage of Mie scattering model and Fraunhofer diffraction model are discussed. The result shows that 1) the Fraunhofer diffraction model is simple in design and fast in operation, which is quite suitable for on-line control and 2) the intensity and energy distribution of diffracted light of both the Mie scattering model and the Fraunhofer theoretical model are compared and researched. Feasibility of using the Fraunhofer diffraction model to replace the Mie scattering model in measuring particles in coal water slurry is demonstrated.
无
2008-01-01
On the basis of previous work,we develop a middle and low latitude theoretical ionospheric model in this paper,named Theoretical lonospheric Model of the Earth in the InstRute of Geology and Geophysics,Chinese Academy of Sciences(TIME-IGGCAS).TIME-IGGCAS solves the equations of mass continuity,motion and energy of electron and ions self-consistently and uses an eccentric dipole field approximation to the Earth's magnetic field.We combine the Eulerian and Lagrangian approaches in the model and take account of the plasma ExB drift velocity.Calculation results reveal that the model is steady and credible and can reproduce most large-scale features of ionosphere.By using TIME-IGGCAS,we carried out an observation system data assimilation experiment.Assimilation results show that the ExB drift velocity can be accurately estimated by ingesting the observed foF2 and hmF2 into the model applying nonlinear least-square fit method.We suggest that this work is of great significance in the development of ionospheric data assimilation model to give better nowcast and forecast of ionosphere.
Johnson, Marcus L.; Taasoobshirazi, Gita; Kestler, Jessica L.; Cordova, Jackie R.
2015-01-01
We tested a theoretical model of college students' ratings of messengers of resilience and models of resilience, students' own perceived resilience, regulatory strategy use and achievement. A total of 116 undergraduates participated in this study. The results of a path analysis indicated that ratings of models of resilience had a direct effect on…
Jennings, Karen M
2017-08-18
Using a nursing theoretical framework to understand, elucidate, and propose nursing research is fundamental to knowledge development. This article presents the Roy Adaptation Model as a theoretical framework to better understand individuals with anorexia nervosa during acute treatment, and the role of nursing assessments and interventions in the promotion of weight restoration. Nursing assessments and interventions situated within the Roy Adaptation Model take into consideration how weight restoration does not occur in isolation but rather reflects an adaptive process within external and internal environments, and has the potential for more holistic care.
Algebraic Specifications, Higher-order Types and Set-theoretic Models
Kirchner, Hélène; Mosses, Peter David
2001-01-01
In most algebraic specification frameworks, the type system is restricted to sorts, subsorts, and first-order function types. This is in marked contrast to the so-called model-oriented frameworks, which provide higer-order types, interpreted set-theoretically as Cartesian products, function spaces......, and power-sets. This paper presents a simple framework for algebraic specifications with higher-order types and set-theoretic models. It may be regarded as the basis for a Horn-clause approximation to the Z framework, and has the advantage of being amenable to prototyping and automated reasoning. Standard...
The theoretical development of the cascade model excimer laser irradiation on the organ of vision
V. N. Trubilin
2012-01-01
Full Text Available Authors analyzed the baseline (Pershin K. B., 2000 and advanced (trubilin V. N Pozharitskii M. D., 2011 theoretical model of the cascade excimer laser effects on eyesight.the analysis indicates a lack of elaboration of issues related to the cascade of «a priori measures» aimed at medical and psycho- logical prediction «quality of life» and post-operative rehabilitation. In theory, authors suggest further improvement of the cascade model of excimer laser irradiation on the organ of vision. the proposed theoretical concepts will provide a practical matter, improvefunctional and subjective results of the excimer laser correction of refractive errors.
A Theoretical Extension of the Technology Acceptance Model: Four Longitudinal Field Studies
Viswanath Venkatesh; Fred D. Davis
2000-01-01
The present research develops and tests a theoretical extension of the Technology Acceptance Model (TAM) that explains perceived usefulness and usage intentions in terms of social influence and cognitive instrumental processes. The extended model, referred to as TAM2, was tested using longitudinal data collected regarding four different systems at four organizations (N = 156), two involving voluntary usage and two involving mandatory usage. Model constructs were measured at three points in ti...
Theoretical Model of User Acceptance: In the View of Measuring Success in Web Personalization
Amin, Mohd Afandi Md; Nayak, Richi
2010-01-01
International audience; This paper attempts to develop a theoretical acceptance model for measuring Web personalization success. Key factors impacting Web personalization acceptance are identified from a detailed literature review. The final model is then cast in a structural equation modeling (SEM) framework comprising nineteen manifest variables, which are grouped into three focal behaviors of Web users. These variables could provide a framework for better understanding of numerous factors ...
Theoretical modeling of infrared spectra of the hydrogen and deuterium bond in aspirin crystal
Ghalla, Houcine; Rekik, Najeh; Michta, Anna; Oujia, Brahim; Flakus, Henryk T.
2010-01-01
An extended quantum theoretical approach of the ν IR lineshape of cyclic dimers of weakly H-bonded species is proposed. We have extended a previous approach [M.E.-A. Benmalti, P. Blaise, H.T. Flakus, O. Henri-Rousseau, Chem. Phys. 320 (2006) 267] by accounting for the anharmonicity of the slow mode which is described by a "Morse" potential in order to reproduce the polarized infrared spectra of the hydrogen and deuterium bond in acetylsalicylic acid (aspirin) crystals. From comparison of polarized IR spectra of isotopically neat and isotopically diluted aspirin crystals it resulted that centrosymmetric aspirin dimer was the bearer of the crystal main spectral properties. In this approach, the adiabatic approximation is performed for each separate H-bond bridge of the dimer and a strong non-adiabatic correction is introduced into the model via the resonant exchange between the fast mode excited states of the two moieties. Within the strong anharmonic coupling theory, according to which the X-H→⋯Y high-frequency mode is anharmonically coupled to the H-bond bridge, this model incorporated the Davydov coupling between the excited states of the two moieties, the quantum direct and indirect dampings and the anharmonicity for the H-bond bridge. The spectral density is obtained within the linear response theory by Fourier transform of the damped autocorrelation functions. The evaluated spectra are in fairly good agreement with the experimental ones by using a minimum number of independent parameters. The effect of deuteration has been well reproduced by reducing simply the angular frequency of the fast mode and the anharmonic coupling parameter.
A theoretical extraction scheme of transport information based on exclusion models
Chen Hua; Du Lei; Qu Cheng-Li; Li Wei-Hua; He Liang; Chen Wen-Hao; Sun Peng
2010-01-01
In order to explore how to extract more transport information from current fluctuation, a theoretical extraction scheme is presented in a single barrier structure based on exclusion models, which include counter-flows model and tunnel model. The first four cumulants of these two exclusion models are computed in a single barrier structure, and their characteristics are obtained. A scheme with the help of the first three cumulants is devised to check a transport process to follow the counter-flows model, the tunnel model or neither of them. Time series generated by Monte Carlo techniques is adopted to validate the abstraction procedure, and the result is reasonable.
A theoretical model to describe progressions and regressions for exercise rehabilitation.
Blanchard, Sam; Glasgow, Phil
2014-08-01
This article aims to describe a new theoretical model to simplify and aid visualisation of the clinical reasoning process involved in progressing a single exercise. Exercise prescription is a core skill for physiotherapists but is an area that is lacking in theoretical models to assist clinicians when designing exercise programs to aid rehabilitation from injury. Historical models of periodization and motor learning theories lack any visual aids to assist clinicians. The concept of the proposed model is that new stimuli can be added or exchanged with other stimuli, either intrinsic or extrinsic to the participant, in order to gradually progress an exercise whilst remaining safe and effective. The proposed model maintains the core skills of physiotherapists by assisting clinical reasoning skills, exercise prescription and goal setting. It is not limited to any one pathology or rehabilitation setting and can adapted by any level of skilled clinician.
A Physically Based Theoretical Model of Spore Deposition for Predicting Spread of Plant Diseases.
Isard, Scott A; Chamecki, Marcelo
2016-03-01
A physically based theory for predicting spore deposition downwind from an area source of inoculum is presented. The modeling framework is based on theories of turbulence dispersion in the atmospheric boundary layer and applies only to spores that escape from plant canopies. A "disease resistance" coefficient is introduced to convert the theoretical spore deposition model into a simple tool for predicting disease spread at the field scale. Results from the model agree well with published measurements of Uromyces phaseoli spore deposition and measurements of wheat leaf rust disease severity. The theoretical model has the advantage over empirical models in that it can be used to assess the influence of source distribution and geometry, spore characteristics, and meteorological conditions on spore deposition and disease spread. The modeling framework is refined to predict the detailed two-dimensional spatial pattern of disease spread from an infection focus. Accounting for the time variations of wind speed and direction in the refined modeling procedure improves predictions, especially near the inoculum source, and enables application of the theoretical modeling framework to field experiment design.
T. Thorvaldsen
2015-01-01
Full Text Available Mathematical models are investigated and suggested for the calculation of the elastic stiffness of polymer nanocomposites. Particular emphasis is placed on the effect on the elastic stiffness from agglomerates and the particle interphase properties. The multiphase Mori-Tanaka model and an interphase model are considered as two relevant models. These models only include and require the designation of a few system independent parameters with a clear physical meaning. Extensions of the models are also presented. The model calculations are compared to results from other models, as well as experimental data for different nanocomposites. For nanocomposites with spherical particles and with fiber-like particles, the suggested models are found to be the most flexible ones and are applicable to estimate the stiffness increase of nanocomposites for both low and high particle volume fractions. The suggested theoretical models can hence be considered as a general multiscale “model toolbox” for analysis of various nanocomposites.
Piper, Llewellyn E
2006-01-01
This article proposes a theoretical model for leaders to use to address organizational human conflict and disruptive behavior in health care organizations. Leadership is needed to improve interpersonal relationships within the workforce. A workforce with a culture of internal conflict will be unable to achieve its full potential to delivery quality patient care.
Theoretical analysis of an iron mineral-based magnetoreceptor model in birds
Solov'yov, Ilia; Greiner, Walter
2007-01-01
involves two types of iron minerals (magnetite and maghemite) that were found in subcellular compartments within sensory dendrites of the upper beak of several bird species. But so far a quantitative evaluation of the proposed receptor is missing. In this article, we develop a theoretical model...
How Career Variety Promotes the Adaptability of Managers: A Theoretical Model
Karaevli, Ayse; Tim Hall, Douglas T.
2006-01-01
This paper presents a theoretical model showing how managerial adaptability develops from career variety over the span of the person's career. By building on the literature of career theory, adult learning and development, and career adjustment, we offer a new conceptualization of managerial adaptability by identifying its behavioral, cognitive,…
Validation of a Theoretical Model of Diagnostic Classroom Assessment: A Mixed Methods Study
Koh, Nancy
2012-01-01
The purpose of the study was to validate a theoretical model of diagnostic, formative classroom assessment called, "Proximal Assessment for Learner Diagnosis" (PALD). To achieve its purpose, the study employed a two-stage, mixed-methods design. The study utilized multiple data sources from 11 elementary level mathematics teachers who…
Aguinis, Herman; Molina-Azorín, José F.
2015-01-01
The microfoundations research agenda presents an expanded theoretical perspective because it considers individuals, their characteristics, and their interactions as relevant variables to help us understand firm-level strategic issues. However, microfoundations empirical research faces unique challenges because processes take place at different levels of analysis and these multilevel processes must be considered simultaneously. We describe multilevel modeling and mixed methods as methodologica...
Toward a Theoretical Model of Learning As It Relates To Simulation Games With Discussion.
Chartier, Myron Raymond
In order for research on the educational utility of simultation games to advance, there must be some stipulation of a set of significant variables. This, in turn, requires the building of testable theoretical models and the formulation of strategic propositions to test their validity. An example of the process involved is as follows. Focusing upon…
INTELLIGENT CAR STYLING TECHNIQUE AND SYSTEM BASED ON A NEW AERODYNAMIC-THEORETICAL MODEL
无
2002-01-01
Car styling technique based on a new theoretical model of automotive aerodynamics is introduced, which is proved to be feasible and effective by wind tunnel tests. Development of a multi-module software system from this technique, including modules of knowledge processing, referential styling and ANN aesthetic evaluation etc, capable of assisting car styling works in an intelligent way, is also presented and discussed.
Balmer, Dorene F.; Richards, Boyd F.; Varpio, Lara
2015-01-01
Using Bourdieu's theoretical model as a lens for analysis, we sought to understand how students experience the undergraduate medical education (UME) milieu, focusing on how they navigate transitions from the preclinical phase, to the major clinical year (MCY), and to the preparation for residency phase. Twenty-two medical students participated in…
Unconscious Determinants of Career Choice and Burnout: Theoretical Model and Counseling Strategy.
Malach-Pines, Ayala; Yafe-Yanai, Oreniya
2001-01-01
Proposes a psychodynamic-existential perspective as a theoretical model that explains career burnout and serves as a basis for a counseling strategy. According to existential theory, the root of career burnout lies in people's need to find existential significance in their life and their sense that their work does not provide it. (Contains 40…
On the Grammar and Model-Theoretic Semantics of Children's Noun Phrases.
Suppes, Patrick
The paper shows informally how model-theoretical semantics may be used by a computer to give a straight-forward analysis of the meaning of children's language. This approach to semantics grows out of the main thrust of work in mathematical logic. It is discussed in the framework of generative grammar and is based on the application of the…
Aguinis, Herman; Molina-Azorín, José F.
2015-01-01
The microfoundations research agenda presents an expanded theoretical perspective because it considers individuals, their characteristics, and their interactions as relevant variables to help us understand firm-level strategic issues. However, microfoundations empirical research faces unique challenges because processes take place at different levels of analysis and these multilevel processes must be considered simultaneously. We describe multilevel modeling and mixed methods as methodologica...
Briggs, Michele Kielty; Shoffner, Marie F.
2006-01-01
Overall spiritual wellness, as well as 4 individual components of spiritual wellness, has been theoretically and empirically linked with depression. Prior to this investigation, no study has examined the relationship between spiritual wellness and depression by using a 4-component measurement model of spiritual wellness. In this study of older…
E-Learning Systems Support of Collaborative Agreements: A Theoretical Model
Aguirre, Sandra; Quemada, Juan
2012-01-01
This paper introduces a theoretical model for developing integrated degree programmes through e-learning systems as stipulated by a collaboration agreement signed by two universities. We have analysed several collaboration agreements between universities at the national, European, and transatlantic level as well as various e-learning frameworks. A…
Models of the Bilingual Lexicon and Their Theoretical Implications for CLIL
Heine, Lena
2014-01-01
Although many advances have been made in recent years concerning the theoretical dimensions of content and language integrated learning (CLIL), research still has to meet the necessity to come up with integrative models that adequately map the interrelation between content and language learning in CLIL contexts. This article will suggest that…
Suggestion for a Theoretical Model for Secondary-Tertiary Transition in Mathematics
Clark, Megan; Lovric, Miroslav
2008-01-01
One of most notable features of existing body of research in transition seems to be the absence of a theoretical model. The suggestion we present in this paper--to view and understand the high school to university transition in mathematics as a modern-day rite of passage--is an attempt at defining such framework. Although dominantly reflecting…
Improvements on Calculation Model of Theoretical Combustion Temperature in a Blast Furnace
WU Sheng-li; LIU Cheng-song; FU Chang-liang; XU Jian; KOU Ming-yin
2011-01-01
On the basis of the existing originally modified calculation models of theoretical combustion temperature（TCT）,some factors,such as the combustion ratio of pulverized coal injection（PCI）,the decomposition heat of PCI and the heat consumption of SiO2 in ash reduced in high temperature environment,were amended and improved to put forward a more comprehensive model for calculating TCT.The influences of each improvement on TCT were studied and the results were analyzed compared with those of traditional model and originally modified model,which showed that the present model could reflect the thermal state of a hearth more effectively.
Theoretical modeling of zircon's crystal morphology according to data of atomistic calculations
Gromalova, Natalia; Nikishaeva, Nadezhda; Eremin, Nikolay
2017-04-01
Zircon is an essential mineral that is used in the U-Pb dating. Moreover, zircon is highly resistant to radioactive exposure. It is of great interest in solving both fundamental and applied problems associated with the isolation of high-level radioactive waste. There is significant progress in forecasting of the most energetically favorable crystal structures at the present time. Unfortunately, the theoretical forecast of crystal morphology at high technological level is under-explored nowadays, though the estimation of crystal equilibrium habit is extremely important in studying the physical and chemical properties of new materials. For the first time, the thesis about relation of the equilibrium shape of a crystal with its crystal structure was put forward in the works by O.Brave. According to it, the idealized habit is determined in the simplest case by a correspondence with the reticular densities Rhkl of individual faces. This approach, along with all subsequent corrections, does not take into account the nature of atoms and the specific features of the chemical bond in crystals. The atomistic calculations of crystal surfaces are commonly performed using the energetic characteristics of faces, namely, the surface energy (Esurf), which is a measure of the thermodynamic stability of the crystal face. The stable crystal faces are characterized by small positive values of Esurf. As we know from our previous research (Gromalova et al.,2015) one of the constitutive factors affecting the value of the surface energy in calculations is a choice of potentials model. In this regard, we studied several sets of parameters of atomistic interatomic potentials optimized previously. As the first test model («Zircon 1») were used sets of interatomic potentials of interaction Zr-O, Si-O and O-O in the form of Buckingham potentials. To improve playback properties of zircon additionally used Morse potential for a couple of Zr-Si, as well as the three-particle angular harmonic
A theoretical model for Reynolds-stress and dissipation-rate budgets in near-wall region
陆利蓬; 陈矛章
2000-01-01
A 3-D wave model for the turbulent coherent structures in near-wall region is proposed. The transport nature of the Reynolds stresses and dissipation rate of the turbulence kinetic energy are shown via computation based on the theoretical model. The mean velocity profile is also computed by using the same theoretical model. The theoretical results are in good agreement with those found from DNS, indicating that the theoretical model proposed can correctly describe the physical mechanism of turbulence in near wail region and it thus possibly opens a new way for turbulence modeling in this region.
A theoretical model for Reynolds-stress and dissipation-rate budgets in near-wall region
无
2000-01-01
A 3-D wave model for the turbulent coherent structures in near-wall region is proposed. The transport nature of the Reynolds stresses and dissipation rate of the turbulence kinetic energy are shown via computation based on the theoretical model. The mean velocity profile is also computed by using the same theoretical model. The theoretical results are in good agreement with those found from DNS, indicating that the theoretical model proposed can correctly describe the physical mechanism of turbulence in near wall region and it thus possibly opens a new way for turbulence modeling in this region.
GRAPH THEORETICAL AND NETWORKS APPROACH FOR THE DEVELOPMENT OF A LEARNING MODEL – A CASE STUDY
PROF. DR. P. K. SRIMANI
2012-08-01
Full Text Available This paper deals with the graph theoretical approach for developing a framework for the Learning model used to optimise the Mathematical Pathway in children at the elementary level and verifying it by usingNetworks model. Data collected pertaining to the mathematical concepts a child needs to learn at elementary level [Class I to VII] is represented by using Concept Flow Graphs and are optimized by using graph theory techniques and algorithms by rearranging nodes as per the learning progression, partitioning the graphs into subgraphsto represent levels of learning, optimizing the sub-graphs using merging and elimination technique and identifying / marking the optional nodes. The design of the framework by using the graph theoretical approach is validated by the application of the Networks approach and this is used to design the Mathematical Pathwaydriver which is the core component of the Learning model. This approach is novel and the Learning model developed is highly accurate.
Study on Theoretical Modeling of Semi-Active Electro-Rheological Fluid Damper
饶柱石; 傅志方; 张华良
2003-01-01
This paper emphases on analyzing and investigating the mechanical behavior of electro-rheological fluid (ERF) semi-active damper. Theoretical model was developed to describe the relationship between electric field and the resistance force of ERF flowing through two parallel plane electrodes. In the model, the pressure drop along electrodes was supposed to consist of two parts: one related with viscosity and the other related with dynamic yield shear stress. The concept of yield stress in fluence factor was developed inderiving the theoretical formula for calculating the pressure drop in the damper. The influences of some other factors, such as, nonideal Newtonian fluid and temperature have also been taken into account. Numerical and experimental work have been performed to prove the validity of the proposed model. The comparison of both results shows that the developed model is quite effective and practicable.
Theoretical and Empirical Review of Asset Pricing Models: A Structural Synthesis
Saban Celik
2012-01-01
Full Text Available The purpose of this paper is to give a comprehensive theoretical review devoted to asset pricing models by emphasizing static and dynamic versions in the line with their empirical investigations. A considerable amount of financial economics literature devoted to the concept of asset pricing and their implications. The main task of asset pricing model can be seen as the way to evaluate the present value of the pay offs or cash flows discounted for risk and time lags. The difficulty coming from discounting process is that the relevant factors that affect the pay offs vary through the time whereas the theoretical framework is still useful to incorporate the changing factors into an asset pricing models. This paper fills the gap in literature by giving a comprehensive review of the models and evaluating the historical stream of empirical investigations in the form of structural empirical review.
Theoretic model of myocardial revascularization by far Infrared laser and experimental validation
LUO Le; CHEN Xing; ZHANG Ting; ZONG Ren-he; DENG Shan-xi
2009-01-01
A theoretic model of myocardial revascularization by a far infrared laser has been established and a quantificational rela-tionship between the aperture of laser channel and parameters of laser has been concluded according to thermodynamics and the law of mteraction of far infrared laser and myocardium. The experiment of a carbon dioxide laser revascularization in porcine myocardinm has been done for different laser powers and irradiation time. The relative errors between experi-mental result and theoretic computation are from 13% to 22%. The reasons that cause the errors have been studied in detail.
Rational Design of Lanthanoid Single-Ion Magnets: Predictive Power of the Theoretical Models.
Baldoví, José J; Duan, Yan; Morales, Roser; Gaita-Ariño, Alejandro; Ruiz, Eliseo; Coronado, Eugenio
2016-09-12
We report two new single-ion magnets (SIMs) of a family of oxydiacetate lanthanide complexes with D3 symmetry to test the predictive capabilities of complete active space ab initio methods (CASSCF and CASPT2) and the semiempirical radial effective charge (REC) model. Comparison of the theoretical predictions of the energy levels, wave functions and magnetic properties with detailed spectroscopic and magnetic characterisation is used to critically discuss the limitations of these theoretical approaches. The need for spectroscopic information for a reliable description of the properties of lanthanide SIMs is emphasised.
Evarestov, RA
2015-01-01
This book deals with the theoretical and computational simulation of monoperiodic nanostructures for different classes of inorganic substances. These simulations are related to their synthesis and experimental studies. A theoretical formalism is developed to describe 1D nanostructures with symmetric shapes and morphologies. Three types of models are considered for this aim: (i) nanotubes (rolled from 2D nanolayers and described within the formalism of line symmetry groups); (ii) nanoribbons (obtained from 2D nanolayers by their cutting along the chosen direction of translation); (iii) nanowire
Xiong Li
2011-12-01
Full Text Available Deep displacement observation is one basic means of landslide dynamic study and early warning monitoring and a key part of engineering geological investigation. In our previous work, we proposed a novel electromagnetic induction-based deep displacement sensor (I-type to predict deep horizontal displacement and a theoretical model called equation-based equivalent loop approach (EELA to describe its sensing characters. However in many landslide and related geological engineering cases, both horizontal displacement and vertical displacement vary apparently and dynamically so both may require monitoring. In this study, a II-type deep displacement sensor is designed by revising our I-type sensor to simultaneously monitor the deep horizontal displacement and vertical displacement variations at different depths within a sliding mass. Meanwhile, a new theoretical modeling called the numerical integration-based equivalent loop approach (NIELA has been proposed to quantitatively depict II-type sensors’ mutual inductance properties with respect to predicted horizontal displacements and vertical displacements. After detailed examinations and comparative studies between measured mutual inductance voltage, NIELA-based mutual inductance and EELA-based mutual inductance, NIELA has verified to be an effective and quite accurate analytic model for characterization of II-type sensors. The NIELA model is widely applicable for II-type sensors’ monitoring on all kinds of landslides and other related geohazards with satisfactory estimation accuracy and calculation efficiency.
Shentu, Nanying; Zhang, Hongjian; Li, Qing; Zhou, Hongliang; Tong, Renyuan; Li, Xiong
2012-01-01
Deep displacement observation is one basic means of landslide dynamic study and early warning monitoring and a key part of engineering geological investigation. In our previous work, we proposed a novel electromagnetic induction-based deep displacement sensor (I-type) to predict deep horizontal displacement and a theoretical model called equation-based equivalent loop approach (EELA) to describe its sensing characters. However in many landslide and related geological engineering cases, both horizontal displacement and vertical displacement vary apparently and dynamically so both may require monitoring. In this study, a II-type deep displacement sensor is designed by revising our I-type sensor to simultaneously monitor the deep horizontal displacement and vertical displacement variations at different depths within a sliding mass. Meanwhile, a new theoretical modeling called the numerical integration-based equivalent loop approach (NIELA) has been proposed to quantitatively depict II-type sensors' mutual inductance properties with respect to predicted horizontal displacements and vertical displacements. After detailed examinations and comparative studies between measured mutual inductance voltage, NIELA-based mutual inductance and EELA-based mutual inductance, NIELA has verified to be an effective and quite accurate analytic model for characterization of II-type sensors. The NIELA model is widely applicable for II-type sensors' monitoring on all kinds of landslides and other related geohazards with satisfactory estimation accuracy and calculation efficiency.
Identifying Tipping Points in a Decision-Theoretic Model of Network Security
Heimann, C. F. Larry; Nochenson, Alan
2012-01-01
Although system administrators are frequently urged to protect the machines in their network, the fact remains that the decision to protect is far from universal. To better understand this decision, we formulate a decision-theoretic model of a system administrator responsible for a network of size n against an attacker attempting to penetrate the network and infect the machines with a virus or similar exploit. By analyzing the model we are able to demonstrate the cost sensitivity of smaller n...
A Theoretical Approach to Financial Therapy: The Development of the Ford Financial Empowerment Model
Kristy L. Archuleta; Joyce A. Baptist; Megan R. Ford
2012-01-01
The purpose of this paper is to introduce an integrative approach to working with clients experiencing problems related to financial disempowerment. The multi-phase model integrates three theoretically-driven psychotherapy approaches, including cognitive behavioral, narrative, and Virginia Satir’s experiential therapies, and financial counseling techniques to increase one’s sense of financial empowerment. A case study is included to demonstrate the applicability and effectiveness of the model...
Family Leadership: Constructing and Testing a Theoretical Model of Family Well-Being
Galbraith, Kevin A.
2000-01-01
Leadership in organizational contexts has received considerable attention through the years. Although much is known about what constitutes effective leadership in an organizational setting, little is known about leadership as it pertains to the family. To address this limitation, a theoretical model of family leadership was developed. This model draws on transformational leadership and proposes five areas in which leadership could be carried out to lead and strengthen the family unit. These f...
Experiments to test theoretical models of the polarization of light by rough surfaces
Geake, J. E.; Geake, M.; Zellner, B. H.
1984-01-01
A number of attempts have been made to provide theoretical models of the physical processes involved in the polarization of light scattered by a rough surface, such as the regolith of an atmosphereless planet. Some laboratory experiments designed to test different aspects of these models are described. It is concluded that double Fresnel reflection is usually the dominant process in producing negative polarization, but that diffraction effects may play a significant part in double events involving small-scale surface features.
A Theoretical Approach to Financial Therapy: The Development of the Ford Financial Empowerment Model
Kristy L. Archuleta; Joyce A. Baptist; Megan R. Ford
2012-01-01
The purpose of this paper is to introduce an integrative approach to working with clients experiencing problems related to financial disempowerment. The multi-phase model integrates three theoretically-driven psychotherapy approaches, including cognitive behavioral, narrative, and Virginia Satir’s experiential therapies, and financial counseling techniques to increase one’s sense of financial empowerment. A case study is included to demonstrate the applicability and effectiveness of the model...
Dias, Natália Martins; Gomes,Cristiano Mauro Assis; Reppold, Caroline Tozzi; Fioravanti-Bastos, Ana Carolina; Pires,Emmy Uehara; Carreiro, Luiz Renato Rodrigues; SEABRA,Alessandra Gotuzo
2015-01-01
Despite relative consensus on the existence of three basic executive functions (EF) (inhibition, working memory and cognitive flexibility) there is narrower knowledge on its organization and contribution to task solution. The study tested different theoretical models about the structure and composition of EF. The correlation matrix of Miyake et al. (2000), which evaluated university students in a set of 15 EF tasks, was adopted. Model 1 displays a general factor and specific components. In mo...
Romain Morlhon
2015-01-01
Full Text Available Building Information Modeling (BIM has become a widely accepted tool to overcome the many hurdles that currently face the Architecture, Engineering and Construction industries. However, implementing such a system is always complex and the recent introduction of BIM does not allow organizations to build their experience on acknowledged standards and procedures. Moreover, data on implementation projects is still disseminated and fragmentary. The objective of this study is to develop an assistance model for BIM implementation. Solutions that are proposed will help develop BIM that is better integrated and better used, and take into account the different maturity levels of each organization. Indeed, based on Critical Success Factors, concrete activities that help in implementation are identified and can be undertaken according to the previous maturity evaluation of an organization. The result of this research consists of a structured model linking maturity, success factors and actions, which operates on the following principle: once an organization has assessed its BIM maturity, it can identify various weaknesses and find relevant answers in the success factors and the associated actions.
无
2002-01-01
In this paper, a theoretical and numerical as-sessment of the validity of Eulerian truncation in stochastic modeling is presented. Specifically, we analyze and compare theoretically various existing Eulerian-based first-order tech-niques with and without invoking "Eulerian truncation" and quantify the terms truncated and retained in the stochastic per-turbation equations using high resolution Monte Carlo simula-tions. We also analyze and compare numerically various exist-ing Eulerian-based first-order techniques and Monte Carlo simulation. The obtained results have demonstrated theoreti-cally and numerically that existing Eulerian-based stochastic perturbation techniques are equivalent. The terms truncated are indeed one order higher than those retained. Therefore,we conclude that "Eulerian truncation" is mathematically con-sistent and asymptotic.
Establishment and Validation for the Theoretical Model of the Vehicle Airbag
ZHANG Junyuan; JIN Yang; XIE Lizhe; CHEN Chao
2015-01-01
The current design and optimization of the occupant restralnt system (ORS) are based on numerous actual tests and mathematic simulations. These two methods are overly time-consuming and complex for the concept design phase of the ORS, though they’re quite effective and accurate. Therefore, a fast and directive method of the design and optimization is needed in the concept design phase of the ORS. Since the alrbag system is a crucial part of the ORS, in this paper, a theoretical model for the vehicle alrbag is established in order to clarify the interaction between occupants and alrbags, and further a fast design and optimization method of alrbags in the concept design phase is made based on the proposed theoretical model. First, the theoretical expression of the simplified mechanical relationship between the alrbag’s design parameters and the occupant response is developed based on classical mechanics, then the momentum theorem and the ideal gas state equation are adopted to illustrate the relationship between alrbag’s design parameters and occupant response. By using MATLAB software, the iterative algorithm method and discrete variables are applied to the solution of the proposed theoretical model with a random input in a certaln scope. And validations by MADYMO software prove the validity and accuracy of this theoretical model in two principal design parameters, the inflated gas mass and vent diameter, within a regular range. This research contributes to a deeper comprehension of the relation between occupants and alrbags, further a fast design and optimization method for alrbags’ principal parameters in the concept design phase, and provides the range of the alrbag’s initial design parameters for the subsequent CAE simulations and actual tests.
Establishment and validation for the theoretical model of the vehicle airbag
Zhang, Junyuan; Jin, Yang; Xie, Lizhe; Chen, Chao
2015-05-01
The current design and optimization of the occupant restraint system (ORS) are based on numerous actual tests and mathematic simulations. These two methods are overly time-consuming and complex for the concept design phase of the ORS, though they're quite effective and accurate. Therefore, a fast and directive method of the design and optimization is needed in the concept design phase of the ORS. Since the airbag system is a crucial part of the ORS, in this paper, a theoretical model for the vehicle airbag is established in order to clarify the interaction between occupants and airbags, and further a fast design and optimization method of airbags in the concept design phase is made based on the proposed theoretical model. First, the theoretical expression of the simplified mechanical relationship between the airbag's design parameters and the occupant response is developed based on classical mechanics, then the momentum theorem and the ideal gas state equation are adopted to illustrate the relationship between airbag's design parameters and occupant response. By using MATLAB software, the iterative algorithm method and discrete variables are applied to the solution of the proposed theoretical model with a random input in a certain scope. And validations by MADYMO software prove the validity and accuracy of this theoretical model in two principal design parameters, the inflated gas mass and vent diameter, within a regular range. This research contributes to a deeper comprehension of the relation between occupants and airbags, further a fast design and optimization method for airbags' principal parameters in the concept design phase, and provides the range of the airbag's initial design parameters for the subsequent CAE simulations and actual tests.
A review of game-theoretic models of road user behaviour.
Elvik, Rune
2014-01-01
This paper reviews game-theoretic models that have been developed to explain road user behaviour in situations where road users interact with each other. The paper includes the following game-theoretic models: 1.A general model of the interaction between road users and their possible reaction to measures improving safety (behavioural adaptation).2.Choice of vehicle size as a Prisoners’ dilemma game.3.Speed choice as a co-ordination game.4.Speed compliance as a game between drivers and the police.5.Merging into traffic from an acceleration lane as a mixed-strategy game.6.Choice of level of attention in following situations as an evolutionary game.7.Choice of departure time to avoid congestion as variant of a Prisoners’ dilemma game.8.Interaction between cyclists crossing the road and car drivers.9.Dipping headlights at night well ahead of the point when glare becomes noticeable.10.Choice of evasive action in a situation when cars are on collision course. The models reviewed are different in many respects, but a common feature of the models is that they can explain how informal norms of behaviour can develop among road users and be sustained even if these informal norms violate the formal regulations of the traffic code. Game-theoretic models are not applicable to every conceivable interaction between road users or to situations in which road users choose behaviour without interacting with other road users. Nevertheless, it is likely that game-theoretic models can be applied more widely than they have been until now.
Sharma, S. K.
2012-12-01
A number of experimental elastic light scattering studies have been performed in the past few years with the aim of developing automated in vivo tools for differentiating a healthy red blood cell from a Plasmodium falciparum infected cell. This paper examines some theoretical aspects of the problem. An attempt has been made to simulate the scattering patterns of healthy as well as infected individual red blood cells. Two models, namely, a homogeneous sphere model and a coated sphere model have been considered. The scattering patterns predicted by these models are examined. A possible method for discriminating infected red blood cells from healthy ones has been suggested.
Theoretical models of pentamidine analogs activity based on their DNA minor groove complexes.
Zołek, Teresa; Maciejewska, Dorota
2010-05-01
The B-DNA binding property of pentamidine analogs was analyzed employing molecular dynamic simulations and UV-vis absorption spectroscopy. Their AATT and ATAT sequence preferences were also examined. In theoretical energy computations, we considered two solvation models: the implicit model I, where the solvent is characterized by a dielectric constant and the explicit model E, where water molecules are treated as discrete entities. The binding energy correlates well with the increase of melting temperature of the 5'-d(CGCGAATTCGCG)(2)-3' and 5'-d(CGCGATATCGCG)(2)-3' dodecamers after complexation with ligands (DeltaTm), and deduced models predicted adequately the DNA affinities of the studied diamidines.
C.C. Hunault; J.D.F. Habbema (Dik); M.J.C. Eijkemans (René); J.A. Collins (John); J.L.H. Evers (Johannes); E.R. te Velde (Egbert)
2004-01-01
textabstractBACKGROUND: Several models have been published for the prediction of spontaneous pregnancy among subfertile patients. The aim of this study was to broaden the empirical basis for these predictions by making a synthesis of three previously published models. METHODS: We u
C.C. Hunault; J.D.F. Habbema (Dik); M.J.C. Eijkemans (René); J.A. Collins (John); J.L.H. Evers (Johannes); E.R. te Velde (Egbert)
2004-01-01
textabstractBACKGROUND: Several models have been published for the prediction of spontaneous pregnancy among subfertile patients. The aim of this study was to broaden the empirical basis for these predictions by making a synthesis of three previously published models. METHODS: We u
Zheng, Yu; Gao, Yang; Chen, Ruijuan; Wang, Huiquan; Dong, Lei; Dou, Junrong
2016-10-01
Time-varying electromagnetic fields (EMF) can induce some physiological effects in neuronal tissues, which have been explored in many applications such as transcranial magnetic stimulation. Although transmembrane potentials and induced currents have already been the subjects of many theoretical studies, most previous works about this topic are mainly completed by utilizing Maxwell's equations, often by solving a Laplace equation. In previous studies, cells were often considered to be three-compartment models with different electroconductivities in different regions (three compartments are often intracellular regions, membrane, and extracellular regions). However, models like that did not take dynamic ion channels into consideration. Therefore, one cannot obtain concrete ionic current changes such as potassium current change or sodium current change by these models. The aim of the present work is to present a new and more detailed model for calculating transmembrane potentials and ionic currents induced by time-varying EMF. Equations used in the present paper originate from Nernst-Plank equations, which are ionic current-related equations. The main work is to calculate ionic current changes induced by EMF exposure, and then transmembrane potential changes are calculated with Hodgkin-Huxley model. Bioelectromagnetics. 37:481-492, 2016. © 2016 Wiley Periodicals, Inc.
Olofsson, Isabelle; Fredriksson, Anders [Golder Associates AB, Stockholm (Sweden)
2005-05-15
The Swedish Nuclear and Fuel Management Company (SKB) is conducting Preliminary Site Investigations at two different locations in Sweden in order to study the possibility of a Deep Repository for spent fuel. In the frame of these Site Investigations, Site Descriptive Models are achieved. These products are the result of an interaction of several disciplines such as geology, hydrogeology, and meteorology. The Rock Mechanics Site Descriptive Model constitutes one of these models. Before the start of the Site Investigations a numerical method using Discrete Fracture Network (DFN) models and the 2D numerical software UDEC was developed. Numerical simulations were the tool chosen for applying the theoretical approach for characterising the mechanical rock mass properties. Some shortcomings were identified when developing the methodology. Their impacts on the modelling (in term of time and quality assurance of results) were estimated to be so important that the improvement of the methodology with another numerical tool was investigated. The theoretical approach is still based on DFN models but the numerical software used is 3DEC. The main assets of the programme compared to UDEC are an optimised algorithm for the generation of fractures in the model and for the assignment of mechanical fracture properties. Due to some numerical constraints the test conditions were set-up in order to simulate 2D plane strain tests. Numerical simulations were conducted on the same data set as used previously for the UDEC modelling in order to estimate and validate the results from the new methodology. A real 3D simulation was also conducted in order to assess the effect of the '2D' conditions in the 3DEC model. Based on the quality of the results it was decided to update the theoretical model and introduce the new methodology based on DFN models and 3DEC simulations for the establishment of the Rock Mechanics Site Descriptive Model. By separating the spatial variability into two
Risk factors for a pressure-related deep tissue injury: a theoretical model.
Gefen, Amit
2007-06-01
Pressure-related deep tissue injury is the term recommended by the United States National Pressure Ulcer Advisory Panel to describe a potentially life-threatening form of pressure ulcers, characterized by the presence of necrotic tissue under intact skin, and associated with prolonged compression of muscle tissue under bony prominences. In this study, a theoretical model was used to determine the relative contributions of the backrest inclination angle during prolonged wheelchair sitting, the muscle tissue stiffness and curvature of the ischial tuberosities (ITs) to the risk for injury in the gluteus muscles that pad the IT bones during sitting. The model is based on Hertz's theory for analysis of contact pressures between a rigid half-sphere (bone) and an elastic half-space (muscle). Hertz's theory is coupled with an injury threshold and damage law for muscle-both obtained in previous studies in rats. The simulation outputs the time-dependent bone-muscle contact pressures and the injured area in the gluteus. We calculated the full-size (asymptotic) injured area in the gluteus and the time for injury onset for different sitting angles alpha (90-150 degrees), muscle tissue long-term shear moduli G (250-1,200 Pa) and bone diameters D (8-18 mm). We then evaluated the sensitivity of model results to variations in these parameters, in order to determine how injury predictions are affected. In reclined sitting (alpha=150 degrees) the full-size injured area was approximately 2.1-fold smaller and the time for injury onset was approximately 1.3-fold longer compared with erect sitting (alpha=90 degrees). For greater G the full-size injured area was smaller but the time for injury onset was shorter, e.g., increasing G from 250 to 1200 Pa decreased the full-size injured area approximately 2.5-fold, but shortened the time for injury onset 6.2-fold. For smaller D the time for injury onset dropped, e.g., decreased approximately 1.5-fold when D decreased from 18 to 8 mm
Minodora Maria PASARE
2014-05-01
Full Text Available In this paper is about of the Hays-Kendall theoretical model of testing the microhardness of the composites materials of NiP/SiC type. We used an indenter to establish the microhardness of the composite and different types of loads. The microhardness can be interpreted using a theoretical model Hays-Kendall and the Kick model.
周又和; 郑晓静
1999-01-01
The quantitative analysis shows that no theoretical model for 3-d magnetoelastic bodies, in literatures to date, can commonly simulate two kinds of distinct experimental phenomena on magnetoelastic interaction of ferromagnetic structures. This makes it difficult to effectively discribe the magnetoelastic mechanical behavior of structures with complex geometry, such as shells. Therefore, it is a key step for simulating magnetoelastic mechanical characteristics of structures with complex geometry to establish a 3-d model which also can commonly characterize the two distinct experimental phenomena. A theoretical model for three dimension magnetizable elastic bodies, which is commonly suitable for the two kinds of experimental phenomena on magnetoelastic interaction of ferromagnetic plates, is presented by the variational principle for the total energy functional of the coupling system of the 3-d ferromagnetic bodies. It is found that for the case of linear isotropic magnetic materials, the magnetic forces
Ahlroth, S.
2001-01-01
This licentiate thesis tries to bridge the gap between the theoretical and the practical studies in the field of environmental accounting. In the paper, 1 develop an optimal control theory model for adjusting NDP for the effects Of SO{sub 2} and NO{sub x} emissions, and subsequently insert empirically estimated values. The model includes correction entries for the effects on welfare, real capital, health and the quality and quantity of renewable natural resources. In the empirical valuation study, production losses were estimated with dose-response functions. Recreational and other welfare values were estimated by the contingent valuation (CV) method. Effects on capital depreciation are also included. For comparison, abatement costs and environmental protection expenditures for reducing sulfur and nitrogen emissions were estimated. The theoretical model was then utilized to calculate the adjustment to NDP in a consistent manner.
A THEORETICAL MODEL OF SUPPORTING OPEN SOURCE FRONT END INNOVATION THROUGH IDEA MANAGEMENT
Aagaard, Annabeth
2013-01-01
Abstract: Most industries face continuing pressures from rising R&D costs, shortening product lifecycles and global competition. These challenges have increased the focus on shortening development times, which again puts pressure on the efficiency of front end innovation (FEI). In the attempt...... to overcome these various challenges companies are looking for new models to support FEI. This theoretical paper explores in what way idea management may be applied as a tool in facilitation of front end innovation and how this facilitation may be captured in a conceptual model. First, I show through...... a literature study, how idea management and front end innovation are related and how they may support each other. Secondly, I present a theoretical model of how idea management may be applied in support of the open source front end of new product innovations. Thirdly, I present different venues of further...
Sub-millimeter Spatial Oscillations of Newton's Constant: Theoretical Models and Laboratory Tests
Perivolaropoulos, Leandros
2016-01-01
We investigate the viability of sub-millimeter wavelength oscillating deviations from the Newtonian potential at both the theoretical and the experimental/observational level. At the theoretical level such deviations are generic predictions in a wide range of extensions of General Relativity (GR) including $f(R)$ theories, massive Brans-Dicke (BD)- scalar tensor theories, compactified extra dimension models and nonlocal extensions of GR. However, the range of parameters associated with such oscillating deviations is usually connected with instabilities present at the perturbative level. An important exception emerges in nonlocal gravity theories where oscillating deviations from Newtonian potential occur naturally on sub-millimeter scales without any instabilities. As an example of a model with unstable Newtonian oscillations we review an $f(R)$ expansion around General Relativity of the form $f(R)=R+\\frac{1}{6 m^2} R^2$ with $m^2<0$ pointing out possible stabilization mechanisms. As an example of a model ...
Theoretical and Statistical Models for Predicting Flux in Direct Contact Membrane Distillation
Atia E. Khalifa
2014-06-01
Full Text Available Theoretical modelhas been applied to predict the performance of Direct Contact Membrane Distillation (DCMD based on the analysis of heat and mass transfer through the membrane. The performance of DCMD on the account of different operating parameters had been predicted. Feed inlet temperature, coolant inlet temperature, feed flow rate and coolant flow rate are the considered performance variables. Based on the data obtained from theoretical model, statistical analysis of variance (ANOVA was then performed to determine the significant effect of each operating factors on the DCMD system performance. A new regression model was subsequently developed for predicting the performance of the DCMD system. Resultsrevealed that both theoretical and regression models were in good agreement with each other and also with the selected experimental data used for validation. The maximum percentage error between the two models was found to be1.098%. Hence, the developed regression model is adequate for predict the performance of DCMD system within the domain of the considered analysis.
Effect of differentiation of self on adolescent risk behavior: test of the theoretical model.
Knauth, Donna G; Skowron, Elizabeth A; Escobar, Melicia
2006-01-01
Innovative theoretical models are needed to explain the occurrence of high-risk sexual behaviors, alcohol and other-drug (AOD) use, and academic engagement among ethnically diverse, inner-city adolescents. The aim of this study was to test the credibility of a theoretical model based on the Bowen family systems theory to explain adolescent risk behavior. Specifically tested was the relationship between the predictor variables of differentiation of self, chronic anxiety, and social problem solving and the dependent variables of high-risk sexual behaviors, AOD use, and academic engagement. An ex post facto cross-sectional design was used to test the usefulness of the theoretical model. Data were collected from 161 racially/ethnically diverse, inner-city high school students, 14 to 19 years of age. Participants completed self-report written questionnaires, including the Differentiation of Self Inventory, State-Trait Anxiety Inventory, Social Problem Solving for Adolescents, Drug Involvement Scale for Adolescents, and the Sexual Behavior Questionnaire. Consistent with the model, higher levels of differentiation of self related to lower levels of chronic anxiety (p relationship between differentiation of self and social problem solving (p < .001), indicating that differentiation influences social problem solving through chronic anxiety. Higher levels of social problem solving were related to less drug use (p < .05), less high-risk sexual behaviors (p < .01), and an increase in academic engagement (p < .01). Findings support the theoretical model's credibility and provide evidence that differentiation of self is an important cognitive factor that enables adolescents to manage chronic anxiety and motivates them to use effective problem solving, resulting in less involvement in health-comprising behaviors and increased academic engagement.
Dirba, I.; Kleperis, J.
2011-01-01
Analytical and numerical modelling is performed for the linear actuator of a parallel path magnet motor. In the model based on finite-element analysis, the 3D problem is reduced to a 2D problem, which is sufficiently precise in a design aspect and allows modelling the principle of a parallel path motor. The paper also describes a relevant numerical model and gives comparison with experimental results. The numerical model includes all geometrical and physical characteristics of the motor components. The magnetic flux density and magnetic force are simulated using FEMM 4.2 software. An experimental model has also been developed and verified for the core of switchable magnetic flux linear actuator and motor. The results of experiments are compared with those of theoretical/analytical and numerical modelling.
A note on Black-Scholes pricing model for theoretical values of stock options
Edeki, S. O.; Ugbebor, O. O.; Owoloko, E. A.
2016-02-01
In this paper, we consider some conditions that transform the classical Black-Scholes Model for stock options valuation from its partial differential equation (PDE) form to an equivalent ordinary differential equation (ODE) form. In addition, we propose a relatively new semi-analytical method for the solution of the transformed Black-Scholes model. The obtained solutions via this method can be used to find the theoretical values of the stock options in relation to their fair prices. In considering the reliability and efficiency of the models, we test some cases and the results are in good agreement with the exact solution.
A sigma model field theoretic realization of Hitchin's generalized complex geometry
Zucchini, Roberto [Dipartimento di Fisica, Universita degli Studi di Bologna, V. Irnerio 46, I-40126 Bologna (Italy); I.N.F.N., sezione di Bologna (Italy)]. E-mail: zucchinir@bo.infn.it
2004-11-01
We present a sigma model field theoretic realization of Hitchin's generalized complex geometry, which recently has been shown to be relevant in compactifications of superstring theory with fluxes. Hitchin sigma model is closely related to the well known Poisson sigma model, of which it has the same field content. The construction shows a remarkable correspondence between the (twisted) integrability conditions of generalized almost complex structures and the restrictions on target space geometry implied by the Batalin-Vilkovisky classical master equation. Further, the (twisted) classical Batalin-Vilkovisky cohomology is related non trivially to a generalized Dolbeault cohomology. (author)
A sigma model field theoretic realization of Hitchin's generalized complex geometry
Zucchini, R
2004-01-01
We present a sigma model field theoretic realization of Hitchin's generalized complex geometry, which recently has been shown to be relevant in compactifications of superstring theory with fluxes. Hitchin sigma model is closely related to the well known Poisson sigma model, of which it has the same field content. The construction shows a remarkable correspondence between the (twisted) integrability conditions of generalized almost complex structures and the restrictions on target space geometry implied by the Batalin--Vilkovisky classical master equation. Further, the (twisted) classical Batalin--Vilkovisky cohomology is related non trivially to a generalized Dolbeault cohomology.
AN Zhi-Wu; WANG Xiao-Min; LI Ming-Xuan; DENG Ming-Xi; MAO Jie
2009-01-01
Based on the exact solutions for the second-harmonic generations of the fundamental longitudinal and transverse waves propagating normally through a thin elastic layer between two solids, the approximate representations termed as 'nonlinear spring models' relating the stresses and displacements on both sides of the interface are rigorously developed by asymptotic expansions of the wave fields for an elastic layer in the limit of small thickness to wavelength ratio. The applicability for the so-called nonlinear spring models is numerically analyzed by comparison with exact solutions for the second harmonic wave reflections. The present nonlinear spring models lay a theoretical foundation to evaluate the interracial properties by nonlinear acoustic waves.
A proposed theoretical model to explain relative age effects in sport.
Hancock, David J; Adler, Ashley L; Côté, Jean
2013-01-01
Exemplary scientific methods describe concepts and provide theories for further testing. For the field of relative age effects (RAEs) in sport, the scientific method appears to be limited to description. The purpose of this paper is to provide a theoretical model to explain RAEs in sport, which researchers can use to test the effects, as well as to generate new hypotheses and recommendations. Herein, we argue that social agents have the largest influence on RAEs. Specifically, we propose that parents influence RAEs through Matthew effects, coaches influence RAEs through Pygmalion effects and athletes influence RAEs through Galatea effects. Integrating these three theories, we propose a model that explains RAEs through these various social agents. This paper provides a theoretical foundation from which researchers can further understand, explain and eventually use to create policies aimed at limiting the negative effect of relative age in sport.
A theoretical model of turbulent fiber suspension and its application to the channel flow
无
2010-01-01
A theoretical model of turbulent fiber suspension is developed by deriving the equations of Reynolds averaged Navier-Stokes,turbulence kinetic energy and turbulence dissipation rate with the additional term of fibers.In order to close the above equations,the equation of probability distribution function for mean fiber orientation is also derived.The theoretical model is applied to the turbulent channel flow and the corresponding equations are solved numerically.The numerical results are verified by comparisons with the experimental ones.The effects of Reynolds number,fiber concentration and fiber aspect-ratio on the velocity profile,turbulent kinetic energy and turbulent dissipation rate are analyzed.Based on the numerical data,the expression for the velocity profile in the turbulent fiber suspension channel flow,which includes the effect of Reynolds number,fiber concentration and aspect-ratio,is proposed.
Model and Set-Theoretic Aspects of Exotic Smoothness Structures on $\\mathbb{R}^4$
Król, Jerzy
2016-01-01
Model-theoretic aspects of exotic smoothness were studied long ago uncovering unexpected relations to noncommutative spaces and quantum theory. Some of these relations were worked out in detail in later work. An important point in the argumentation was the forcing construction of Cohen but without a direct application to exotic smoothness. In this article we assign the set-theoretic forcing on trees to Casson handles and characterize small exotic smooth $R^4$ from this point of view. Moreover, we show how models in some Grothendieck toposes can help describing such differential structures in dimension 4. These results can be used to obtain the deformation of the algebra of usual complex functions to the noncommutative algebra of operators on a Hilbert space. We also discuss the results in the context of the Epstein-Glaser renormalization in QFT.
Theoretical model and optimal design of silicon micromachined ultrasonic imaging transducers
GE; LiFeng
2007-01-01
A theoretical model and mathematical description for silicon micromachined electrostatic or capacitive ultrasonic imaging transducers have been developed. According to the model the basic performance parameters of such a transducer, such as natural frequencies, eigenfunctions, resonance and anti-resonance frequencies, and the mechanical impedance of the diaphragm can be predicted from the geometry of the transducer and property parameters of materials used. The paper reveals that this type of transducers has two basic operation modes, corresponding to the resonance of a mass-spring oscillator comprised of the diaphragm and the air cushion, and the first-order bending mode of the diaphragm itself respectively, and presents an optimal method for extending the bandwidth by making the two modes coupled, and thereby provides a theoretical basis for the optimal design.
Ultraviolet Properties of Primeval Galaxies Theoretical Models from Stellar Population Synthesis
Buzzoni, A
2002-01-01
The ultraviolet luminosity evolution of star-forming galaxies is explored from the theoretical point of view, especially focusing on the theory of UV energetics in simple and composite stellar populations and its relationship to the star formation rate and other main evolutionary parameters. Galaxy emission below 3000 Angstroms directly correlates with actual star formation, not depending on the total mass of the system. A straightforward calibration is obtained, in this sense, from the theoretical models at 1600, 2000 and 2800 Angstroms, and a full comparison is carried out with IUE data and other balloon-borne observations for local galaxies. The claimed role of late-type systems as prevailing contributors to the cosmic UV background is reinforced by our results; at 2000 Angstroms Im irregulars are found in fact nearly four orders of magnitude brighter than ellipticals, per unit luminous mass. The role of dust absorption in the observation of high-redshift galaxies is assessed, comparing model output and ob...
How career variety promotes the adaptability of managers: a theoretical model
Karaevli, Ayşe; Karaevli, Ayse; Hall, Douglas T. Tim
2006-01-01
This paper presents a theoretical model showing how managerial adaptability develops from career variety over the span of the person’s career. By building on the literature of career theory, adult learning and development, and career adjustment, we oVer a new conceptualization of managerial adaptability by identifying its behavioral, cognitive, and socio-emotional dimensions, discuss how these competencies can develop from the variety of managers’ cumulative career experiences, and propose se...
Theoretical Calculation of Rotational Bands of 179Pt in the Particle-Triaxial-Rotor Model
CHEN Guo-Jie; SONG Hui-Chao; LIU Yu-Xin
2005-01-01
Theoretical calculations have been performed for nucleus 179Pt in the particle-triaxial-rotor model with variable moment of inertia. The obtained energy spectrum agrees with the experimental data quite well. The calculated results indicate that the bands 1/2- and 7/2+ are triaxial deformation bands and originate mainly from the v[521]1/2- and v[633]7/2+ configurations respectively.
Yun Chen; Hui Yang
2016-01-01
In the era of big data, there are increasing interests on clustering variables for the minimization of data redundancy and the maximization of variable relevancy. Existing clustering methods, however, depend on nontrivial assumptions about the data structure. Note that nonlinear interdependence among variables poses significant challenges on the traditional framework of predictive modeling. In the present work, we reformulate the problem of variable clustering from an information theoretic pe...
Control Theoretic Modeling and Generated Flow Patterns of a Fish-Tail Robot
Massey, Brian; Morgansen, Kristi; Dabiri, Dana
2003-11-01
Many real-world engineering problems involve understanding and manipulating fluid flows. One of the challenges to further progress in the area of active flow control is the lack of appropriate models that are amenable to control-theoretic studies and algorithm design and also incorporate reasonably realistic fluid dynamic effects. We focus here on modeling and model-verification of bio-inspired actuators (fish-fin type structures) used to control fluid dynamic artifacts that will affect speed, agility, and stealth of Underwater Autonomous Vehicles (UAVs). Vehicles using fish-tail type systems are more maneuverable, can turn in much shorter and more constrained spaces, have lower drag, are quieter and potentially more efficient than those using propellers. We will present control-theoretic models for a simple prototype coupled fluid and mechanical actuator where fluid effects are crudely modeled by assuming only lift, drag, and added mass, while neglecting boundary effects. These models will be tested with different control input parameters on an experimental fish-tail robot with the resulting flow captured with DPIV. Relations between the model, the control function choices, the obtained thrust and drag, and the corresponding flow patterns will be presented and discussed.
A theoretical approach to room acoustic simulations based on a radiative transfer model
Ruiz-Navarro, Juan-Miguel; Jacobsen, Finn; Escolano, José
2010-01-01
A theoretical approach to room acoustic simulations based on a radiative transfer model is developed by adapting the classical radiative transfer theory from optics to acoustics. The proposed acoustic radiative transfer model expands classical geometrical room acoustic modeling algorithms...... by incorporating a propagation medium that absorbs and scatters radiation, handling both diffuse and non-diffuse reflections on boundaries and objects in the room. The main scope of this model is to provide a proper foundation for a wide number of room acoustic simulation models, in order to establish and unify...... their principles. It is shown that this room acoustic modeling technique establishes the basis of two recently proposed algorithms, the acoustic diffusion equation and the room acoustic rendering equation. Both methods are derived in detail using an analytical approximation and a simplified integral equation...
Meta-Theoretical Contributions to the Constitution of a Model-Based Didactics of Science
Ariza, Yefrin; Lorenzano, Pablo; Adúriz-Bravo, Agustín
2016-10-01
There is nowadays consensus in the community of didactics of science (i.e. science education understood as an academic discipline) regarding the need to include the philosophy of science in didactical research, science teacher education, curriculum design, and the practice of science education in all educational levels. Some authors have identified an ever-increasing use of the concept of `theoretical model', stemming from the so-called semantic view of scientific theories. However, it can be recognised that, in didactics of science, there are over-simplified transpositions of the idea of model (and of other meta-theoretical ideas). In this sense, contemporary philosophy of science is often blurred or distorted in the science education literature. In this paper, we address the discussion around some meta-theoretical concepts that are introduced into didactics of science due to their perceived educational value. We argue for the existence of a `semantic family', and we characterise four different versions of semantic views existing within the family. In particular, we seek to contribute to establishing a model-based didactics of science mainly supported in this semantic family.
Theoretical modeling and experimental analysis of solar still integrated with evacuated tubes
Panchal, Hitesh; Awasthi, Anuradha
2016-12-01
In this present research work, theoretical modeling of single slope, single basin solar still integrated with evacuated tubes has been performed based on energy balance equations. Major variables like water temperature, inner glass cover temperature and distillate output has been computed based on theoretical modeling. The experimental setup has been made from locally available materials and installed at Gujarat Power Engineering and Research Institute, Mehsana, Gujarat, India (23.5880°N, 72.3693°E) with 0.04 m depth during 6 months of time interval. From the series of experiments, it is found considerable increment in average distillate output of a solar still when integrated with evacuated tubes not only during daytime but also from night time. In all experimental cases, the correlation of coefficient (r) and root mean square percentage deviation of theoretical modeling and experimental study found good agreement with 0.97 < r < 0.98 and 10.22 < e < 38.4% respectively.
Meta-Theoretical Contributions to the Constitution of a Model-Based Didactics of Science
Ariza, Yefrin; Lorenzano, Pablo; Adúriz-Bravo, Agustín
2016-07-01
There is nowadays consensus in the community of didactics of science (i.e. science education understood as an academic discipline) regarding the need to include the philosophy of science in didactical research, science teacher education, curriculum design, and the practice of science education in all educational levels. Some authors have identified an ever-increasing use of the concept of `theoretical model', stemming from the so-called semantic view of scientific theories. However, it can be recognised that, in didactics of science, there are over-simplified transpositions of the idea of model (and of other meta-theoretical ideas). In this sense, contemporary philosophy of science is often blurred or distorted in the science education literature. In this paper, we address the discussion around some meta-theoretical concepts that are introduced into didactics of science due to their perceived educational value. We argue for the existence of a `semantic family', and we characterise four different versions of semantic views existing within the family. In particular, we seek to contribute to establishing a model-based didactics of science mainly supported in this semantic family.
Marasulov, Akhmat; Saipov, Amangeldi; ?rymbayeva, Kulimkhan; Zhiyentayeva, Begaim; Demeuov, Akhan; Konakbaeva, Ulzhamal; Bekbolatova, Akbota
2016-01-01
The aim of the study is to examine the methodological-theoretical construction bases for development mechanism of an integrated model for a specialist's training and teacher's conceptual-theoretical activity. Using the methods of generalization of teaching experience, pedagogical modeling and forecasting, the authors determine the urgent problems…
Hansson, Lena; Hansson, Örjan; Juter, Kristina; Redfors, Andreas
2015-01-01
This article discusses the role of mathematics during physics lessons in upper-secondary school. Mathematics is an inherent part of theoretical models in physics and makes powerful predictions of natural phenomena possible. Ability to use both theoretical models and mathematics is central in physics. This paper takes as a starting point that the…
Grace, J.B.; Bollen, K.A.
2008-01-01
Structural equation modeling (SEM) holds the promise of providing natural scientists the capacity to evaluate complex multivariate hypotheses about ecological systems. Building on its predecessors, path analysis and factor analysis, SEM allows for the incorporation of both observed and unobserved (latent) variables into theoretically-based probabilistic models. In this paper we discuss the interface between theory and data in SEM and the use of an additional variable type, the composite. In simple terms, composite variables specify the influences of collections of other variables and can be helpful in modeling heterogeneous concepts of the sort commonly of interest to ecologists. While long recognized as a potentially important element of SEM, composite variables have received very limited use, in part because of a lack of theoretical consideration, but also because of difficulties that arise in parameter estimation when using conventional solution procedures. In this paper we present a framework for discussing composites and demonstrate how the use of partially-reduced-form models can help to overcome some of the parameter estimation and evaluation problems associated with models containing composites. Diagnostic procedures for evaluating the most appropriate and effective use of composites are illustrated with an example from the ecological literature. It is argued that an ability to incorporate composite variables into structural equation models may be particularly valuable in the study of natural systems, where concepts are frequently multifaceted and the influence of suites of variables are often of interest. ?? Springer Science+Business Media, LLC 2007.
A theoretical model of co-worker responses to work reintegration processes.
Dunstan, Debra A; Maceachen, Ellen
2014-06-01
Emerging research has shown that co-workers have a significant influence on the return-to-work outcomes of partially fit ill or injured employees. By drawing on theoretical findings from the human resource and wider behavioral sciences literatures, our goal was to formulate a theoretical model of the influences on and outcomes of co-worker responses within work reintegration. From a search of 15 data bases covering the social sciences, business and medicine, we identified articles containing models of the factors that influence co-workers' responses to disability accommodations; and, the nature and impact of co-workers' behaviors on employee outcomes. To meet our goal, we combined identified models to form a comprehensive model of the relevant factors and relationships. Internal consistency and externally validity were assessed. The combined model illustrates four key findings: (1) co-workers' behaviors towards an accommodated employee are influenced by attributes of that employee, the illness or injury, the co-worker themselves, and the work environment; (2) the influences-behaviour relationship is mediated by perceptions of the fairness of the accommodation; (3) co-workers' behaviors affect all work reintegration outcomes; and (4) co-workers' behaviours can vary from support to antagonism and are moderated by type of support required, the social intensity of the job, and the level of antagonism. Theoretical models from the wider literature are useful for understanding the impact of co-workers on the work reintegration process. To achieve optimal outcomes, co-workers need to perceive the arrangements as fair. Perceptions of fairness might be supported by co-workers' collaborative engagement in the planning, monitoring and review of work reintegration activities.
Software for energy modelling: a theoretical basis for improvements in the user interface
Siu, Y.L.
1989-09-01
A philosophical critique of the relationships between theory, knowledge and practice for a range of existing energy modelling styles is presented. In particular, Habermas's ideas are invoked regarding the three spheres of cognitive interest (i.e. technical, practical and emancipatory) and three levels of understanding of knowledge, the construction of an 'ideal speech situation', and the theory of communicative competence and action. These are adopted as a basis for revealing shortcomings of a representative selection of existing computer-based energy modelling styles, and as a springboard for constructing a new theoretical approach. (author).
Team Resilience as a Second-Order Emergent State: A Theoretical Model and Research Directions
Bowers, Clint; Kreutzer, Christine; Cannon-Bowers, Janis; Lamb, Jerry
2017-01-01
Resilience has been recognized as an important phenomenon for understanding how individuals overcome difficult situations. However, it is not only individuals who face difficulties; it is not uncommon for teams to experience adversity. When they do, they must be able to overcome these challenges without performance decrements.This manuscript represents a theoretical model that might be helpful in conceptualizing this important construct. Specifically, it describes team resilience as a second-order emergent state. We also include research propositions that follow from the model. PMID:28861013
Saunders, James A
2015-03-01
Fundamental Christianity and psychology are frequently viewed as incompatible pursuits. However, proponents of the integrationist movement posit that pastoral counselors can utilize principles from psychology if they adopt the premise that all truth is God's truth. Assuming this perspective, Cognitive-Existential Family Therapy (CEFT) - a theoretical integration model compatible with Christian fundamentalism - is proposed. The philosophical assumptions and models of personality, health, and abnormality are explored. Additionally, the article provides an overview of the therapeutic process. © The Author(s) 2015 Reprints and permissions:sagepub.co.uk/journalsPermissions.nav.
Team Resilience as a Second-Order Emergent State: A Theoretical Model and Research Directions
Clint Bowers
2017-08-01
Full Text Available Resilience has been recognized as an important phenomenon for understanding how individuals overcome difficult situations. However, it is not only individuals who face difficulties; it is not uncommon for teams to experience adversity. When they do, they must be able to overcome these challenges without performance decrements.This manuscript represents a theoretical model that might be helpful in conceptualizing this important construct. Specifically, it describes team resilience as a second-order emergent state. We also include research propositions that follow from the model.
Yang, H -Y K; Ricker, P M
2012-01-01
Cosmological constraints derived from galaxy clusters rely on accurate predictions of cluster observable properties, in which feedback from active galactic nuclei (AGN) is a critical component. In order to model the physical effects due to supermassive black holes (SMBH) on cosmological scales, subgrid modeling is required, and a variety of implementations have been developed in the literature. However, theoretical uncertainties due to model and parameter variations are not yet well understood, limiting the predictive power of simulations including AGN feedback. By performing a detailed parameter sensitivity study in a single cluster using several commonly-adopted AGN accretion and feedback models with FLASH, we quantify the model uncertainties in predictions of cluster integrated properties. We find that quantities that are more sensitive to gas density have larger uncertainties (~20% for Mgas and a factor of ~2 for Lx at R500), whereas Tx, Ysz, and Yx are more robust (~10-20% at R500). To make predictions b...
A theoretical model for ionospheric electric fields at mid- and low-latitudes
YU; Tao(余涛); WAN; Weixing(万卫星); LIU; Libo(刘立波)
2003-01-01
A theoretical model for ionospheric electric fields at mid- and Iow-latitudes is developed.In the geomagnetic dipolar coordinate system, we deduce a partial differential equation of electricpotential from the ionospheric dynamo theory. The deduced equation is taken as the fundamentalequation for the present model. The principal parameters for the model input, the thermosphericneutral winds, the densities and temperatures of electrons, ions and neutral atoms and molecules,are obtained from the empirical models HWM93, IRI90 and MSISE90, respectively. In terms of therelaxation iteration method, the partial equations for electric potential are solved successfully, andthen, the ionospheric electric potential, fields, and currents are derived. Our model can reproducethe main features of the ionospheric electrodynamical processes such as the equatorial electric jet(EEJ), so it will be a useful tool for studying the upper atmosphere and ionosphere.
José A. F. O. Correia
2016-01-01
Full Text Available Structural design taking into account fatigue damage requires a thorough knowledge of the behaviour of materials. In addition to the monotonic behaviour of the materials, it is also important to assess their cyclic response and fatigue crack propagation behaviour under constant and variable amplitude loading. Materials whenever subjected to fatigue cracking may exhibit mean stress effects as well as crack closure effects. In this paper, a theoretical model based on the same initial assumptions of the analytical models proposed by Hudak and Davidson and Ellyin is proposed to estimate the influence of the crack closure effects. This proposal based further on Walker’s propagation law was applied to the P355NL1 steel using an inverse analysis (back-extrapolation of experimental fatigue crack propagation results. Based on this proposed model it is possible to estimate the crack opening stress intensity factor, Kop, the relationship between U=ΔKeff/ΔK quantity and the stress intensity factor, the crack length, and the stress ratio. This allows the evaluation of the influence of the crack closure effects for different stress ratio levels, in the fatigue crack propagation rates. Finally, a good agreement is found between the proposed theoretical model and the analytical models presented in the literature.
Dong, Ren G.; Welcome, Daniel E.; McDowell, Thomas W.; Wu, John Z.
2015-01-01
While simulations of the measured biodynamic responses of the whole human body or body segments to vibration are conventionally interpreted as summaries of biodynamic measurements, and the resulting models are considered quantitative, this study looked at these simulations from a different angle: model calibration. The specific aims of this study are to review and clarify the theoretical basis for model calibration, to help formulate the criteria for calibration validation, and to help appropriately select and apply calibration methods. In addition to established vibration theory, a novel theorem of mechanical vibration is also used to enhance the understanding of the mathematical and physical principles of the calibration. Based on this enhanced understanding, a set of criteria was proposed and used to systematically examine the calibration methods. Besides theoretical analyses, a numerical testing method is also used in the examination. This study identified the basic requirements for each calibration method to obtain a unique calibration solution. This study also confirmed that the solution becomes more robust if more than sufficient calibration references are provided. Practically, however, as more references are used, more inconsistencies can arise among the measured data for representing the biodynamic properties. To help account for the relative reliabilities of the references, a baseline weighting scheme is proposed. The analyses suggest that the best choice of calibration method depends on the modeling purpose, the model structure, and the availability and reliability of representative reference data. PMID:26740726
INTRODUCTION: Theoretical Models as Mass Media Practice: Perspectives from the West
2007-01-01
at Reuters Institute in May 2007, from which this collection of papers has been selected. As with the other workshops during the conference, the majority of our panellists were themselves once media practitioners. It is my opinion that this background and inside knowledge of the field in itself can provide......What is journalism? How does it exist and why? How does journalism define itself and in what ways can we make use of looking theoretically at the practice of it? These were the central themes of our workshop; Theoretical Models as Mass Media Practice held at the ‘Minding the Gap’ conference...... an exceptional framework for understanding the workings of mass media while helping the press reflect over these workings too. In a time of change for the journalistic profession, when media convergence is growing; the media is marked by deregulation and fewer journalists are being asked to do more...
Sample correlations of infinite variance time series models: an empirical and theoretical study
Jason Cohen
1998-01-01
Full Text Available When the elements of a stationary ergodic time series have finite variance the sample correlation function converges (with probability 1 to the theoretical correlation function. What happens in the case where the variance is infinite? In certain cases, the sample correlation function converges in probability to a constant, but not always. If within a class of heavy tailed time series the sample correlation functions do not converge to a constant, then more care must be taken in making inferences and in model selection on the basis of sample autocorrelations. We experimented with simulating various heavy tailed stationary sequences in an attempt to understand what causes the sample correlation function to converge or not to converge to a constant. In two new cases, namely the sum of two independent moving averages and a random permutation scheme, we are able to provide theoretical explanations for a random limit of the sample autocorrelation function as the sample grows.
Jun, Xu; Bo, You; Xin, Li; Juan, Cui
2007-12-01
To accurately measure temperatures, a novel temperature sensor based on a quartz tuning fork resonator has been designed. The principle of the quartz tuning fork temperature sensor is that the resonant frequency of the quartz resonator changes with the variation in temperature. This type of tuning fork resonator has been designed with a new doubly rotated cut work at flexural vibration mode as temperature sensor. The characteristics of the temperature sensor were evaluated and the results sufficiently met the target of development for temperature sensor. The theoretical model for temperature sensing has been developed and built. The sensor structure was analysed by finite element method (FEM) and optimized, including tuning fork geometry, tine electrode pattern and the sensor's elements size. The performance curve of output versus measured temperature is given. The results from theoretical analysis and experiments indicate that the sensor's sensitivity can reach 60 ppm °C-1 with the measured temperature range varying from 0 to 100 °C.
Theoretical Calculation Model of Single Rip Tearing Strength for the Nonwoven Composites
QIAN Cheng
2005-01-01
The nonwoven composites have sandwich structure, with the first and third layers being nonwovens and the middle layer of woven fabric. On the basis of tests of the single rip tearing strength and drawing out resistances of both the nonwoven composites and the woven fabric, the single rip tearing failure mechanism of the composites were analyzed.Then theoretical calculation model for the single rip tearing strength was established, which indicates that the breaking strength of warp and weft yarns in the nonwoven composites, the density of warp and weft yarns and drawing out resistances are the main influencing factors. In the end,experimental verification was made, which shows that theoretical values conform to the measured values well.
Designing m-learning for junior registrars--activation of a theoretical model of clinical knowledge.
Kanstrup, Anne Marie; Boye, Niels; Nøhr, Christian
2007-01-01
The MINI-project aims at supporting junior registrars in the learning process of how to utilize their theoretical knowledge from Medical School in everyday clinical reasoning and practice. Due to the nature of the work--concurrent moving, learning and producing--we designed an m-learning application. This paper introduces the possibilities and challenges for design of the m-learning application based on a) analytical findings on learning and mobility as derived from the design case--an emergency medical ward b) theoretical perspectives on medical knowledge, and c) presentation of the design of an m-learning application. The design process was based on user-driven innovation and the paper discusses considerations on how to combine user-drive and generic models.
Theoretical Standard Model Rates of Proton to Neutron Conversions Near Metallic Hydride Surfaces
Widom, A
2006-01-01
The process of radiation induced electron capture by protons or deuterons producing new ultra low momentum neutrons and neutrinos may be theoretically described within the standard field theoretical model of electroweak interactions. For protons or deuterons in the neighborhoods of surfaces of condensed matter metallic hydride cathodes, such conversions are determined in part by the collective plasma modes of the participating charged particles, e.g. electrons and protons. The radiation energy required for such low energy nuclear reactions may be supplied by the applied voltage required to push a strong charged current across a metallic hydride surface employed as a cathode within a chemical cell. The electroweak rates of the resulting ultra low momentum neutron production are computed from these considerations.
Utilisation of theoretical models and frameworks in the process of evidence synthesis.
Godfrey, Christina M; Harrison, Margaret B; Graham, Ian D; Ross-White, Amanda
2010-01-01
A systematic review is a comprehensive enquiry or study of secondary data sources. There is a research question, an a priori articulation of methods and a set of procedures to focus the investigation. Despite these rigorous structures to guide the review, synthesising evidence is a challenging, resource intense and time consuming process. Large volumes of information complicate not only the search functions, but also the conceptualisation of the evidence needed to create the concise and integrated results. Use of a theoretical model or framework could serve as an essential element in effectively focusing the review and designing the methods to respond to the knowledge question. This scoping review sought to confirm the value of models or frameworks used by authors working within traditional methodologies for evidence synthesis. Types of participants The focus of this review was on the context of health care.Types of intervention(s)/phenomena of interest All studies that discussed models or frameworks used specifically to address the process of synthesis were included.Types of studies Discussion, scholarship or methodology papers and reviews were included.Types of outcome All theoretical models or frameworks were described, with specific attention to the purpose of the framework for each study, and the contribution of the framework to the process of synthesis. The search strategy aimed to find both published and unpublished studies. A three-step search strategy was utilised. The databases for published material included CINAHL; Medline; EMBASE; PsycINFO; AMED; Cochrane; Biomed Central; Scirus; and Mednar. Databases for unpublished material included Dissertation Abstracts; Sociological Abstracts; Conference proceedings. The review was a focused scoping review to locate and describe the contribution of theoretical models or frameworks to the process of synthesis. The methodological quality of the discussion papers was therefore not assessed. Data was extracted from
R. Du Preez
2003-10-01
Full Text Available This article is based on the conceptual theoretical model developed in Part 1 of this series of articles. The objective of this research is to identify female apparel consumer market segments on the basis of differentiating lifestyles, shopping orientation, cultural consciousness, store patronage and demographics. These profiles are discussed in full and the implications thereof for retailers, marketers and researchers are highlighted. A new conceptual model is proposed and recommendations are made for further research. Opsomming Hierdie artikel word gebaseer op die konseptuele teoretiese model wat reeds in Deel 1 van hierdie artikelreeks ontwikkel is. Die doel van hierdie navorsing is om marksegmente van vroue klere-kopers te identifiseer na aanleiding van hulle lewenstyle, kooporiëntasie, kulturele bewustheid, winkelvoorkeurgedrag en demografie. Hierdie profiele word volledig beskryf en die implikasies van die verskillende profiele vir kleinhandelaars, bemarkers en navorsers word uitgelig. ’n Nuwe konseptuele model word voorgestel en aanbevelings vir verdere navorsing word gemaak.
A theoretical adaptive model of thermal comfort - Adaptive Predicted Mean Vote (aPMV)
Yao, Runming [School of Construction Management and Engineering, The University of Reading (United Kingdom); Faculty of Urban Construction and Environmental Engineering, Chongqing University (China); Li, Baizhan [Key Laboratory of the Three Gorges Reservoir Region' s Eco-Environment (Ministry of Education), Chongqing University (China); Faculty of Urban Construction and Environmental Engineering, Chongqing University (China); Liu, Jing [School of Construction Management and Engineering, The University of Reading (United Kingdom)
2009-10-15
This paper presents in detail a theoretical adaptive model of thermal comfort based on the ''Black Box'' theory, taking into account factors such as culture, climate, social, psychological and behavioural adaptations, which have an impact on the senses used to detect thermal comfort. The model is called the Adaptive Predicted Mean Vote (aPMV) model. The aPMV model explains, by applying the cybernetics concept, the phenomena that the Predicted Mean Vote (PMV) is greater than the Actual Mean Vote (AMV) in free-running buildings, which has been revealed by many researchers in field studies. An Adaptive coefficient ({lambda}) representing the adaptive factors that affect the sense of thermal comfort has been proposed. The empirical coefficients in warm and cool conditions for the Chongqing area in China have been derived by applying the least square method to the monitored onsite environmental data and the thermal comfort survey results. (author)
Theoretical Framework and Model Design for Beautiful Countryside Construction in China
ZHENG Xiang-qun
2015-04-01
Full Text Available In the context of China today, the process of beautiful countryside construction mainly imitates the patterns of‘urbanization’construction. However, this approach leads to the loss of countryside characteristics and the separation of agricultural culture. Therefore, it's urgent to carry out research of the theoretical framework and model design for beautiful countryside construction. In this paper, based on the analysis of the beautiful countryside construction connotation, the basic theory of beautiful countryside construction was summarized in three aspects: rural complex ecosystem model, multi-functionality of rural model and sustainable development evaluation model. The basic idea of the beautiful countryside construction mode was studied. The design method of beautiful countryside construction mode was proposed in three levels: planning, scheming and evaluating. The research results might offer scientific reference for improving the scientific and operational nature of beautiful countryside construction.
Constraints on field theoretical models for variation of the fine structure constant
Steinhardt, Charles L.
2005-02-01
Recent theoretical ideas and observational claims suggest that the fine structure constant α may be variable. We examine a spectrum of models in which α is a function of a scalar field. Specifically, we consider three scenarios: oscillating α, monotonic time variation of α, and time-independent α that is spatially varying. We examine the constraints imposed upon these theories by cosmological observations, particle detector experiments, and “fifth force” experiments. These constraints are very strong on models involving oscillation but cannot compete with bounds from the Oklo subnuclear reactor on models with monotonic timelike variation of α. One particular model with spatial variation is consistent with all current experimental and observational measurements, including those from two seemingly conflicting measurements of the fine structure constant using the many multiplet method on absorption lines.
A thematic analysis of theoretical models for translational science in nursing: mapping the field.
Mitchell, Sandra A; Fisher, Cheryl A; Hastings, Clare E; Silverman, Leanne B; Wallen, Gwenyth R
2010-01-01
The quantity and diversity of conceptual models in translational science may complicate rather than advance the use of theory. This paper offers a comparative thematic analysis of the models available to inform knowledge development, transfer, and utilization. Literature searches identified 47 models for knowledge translation. Four thematic areas emerged: (1) evidence-based practice and knowledge transformation processes, (2) strategic change to promote adoption of new knowledge, (3) knowledge exchange and synthesis for application and inquiry, and (4) designing and interpreting dissemination research. This analysis distinguishes the contributions made by leaders and researchers at each phase in the process of discovery, development, and service delivery. It also informs the selection of models to guide activities in knowledge translation. A flexible theoretical stance is essential to simultaneously develop new knowledge and accelerate the translation of that knowledge into practice behaviors and programs of care that support optimal patient outcomes.
F. T. Ademiluyi
2013-01-01
Full Text Available A mathematical model was developed for predicting the drying kinetics of spherical particles in a rotary dryer. Drying experiments were carried out by drying fermented ground cassava particles in a bench scale rotary dryer at inlet air temperatures of 115–230°C, air velocities of 0.83 m/s–1.55 m/s, feed mass of 50–500 g, drum drive speed of 8 rpm, and feed drive speed of 100 rpm to validate the model. The data obtained from the experiments were used to calculate the experimental moisture ratio which compared well with the theoretical moisture ratio calculated from the newly developed Abowei-Ademiluyi model. The comparisons and correlations of the results indicate that validation and performance of the established model are rather reasonable.
Rolling force prediction for strip casting using theoretical model and artificial intelligence
CAO Guang-ming; LI Cheng-gang; ZHOU Guo-ping; LIU Zhen-yu; WU Di; WANG Guo-dong; LIU Xiang-hua
2010-01-01
Rolling force for strip casting of 1Cr17 ferritic stainless steel was predicted using theoretical model and artificial intelligence.Solution zone was classified into two parts by kiss point position during casting strip.Navier-Stokes equation in fluid mechanics and stream function were introduced to analyze the rheological property of liquid zone and mushy zone,and deduce the analytic equation of unit compression stress distribution.The traditional hot rolling model was still used in the solid zone.Neural networks based on feedforward training algorithm in Bayesian regularization were introduced to build model for kiss point position.The results show that calculation accuracy for verification data of 94.67% is in the range of+7.0%,which indicates that the predicting accuracy of this model is very high.
Schuwirth, Nele; Reichert, Peter
2013-02-01
For the first time, we combine concepts of theoretical food web modeling, the metabolic theory of ecology, and ecological stoichiometry with the use of functional trait databases to predict the coexistence of invertebrate taxa in streams. We developed a mechanistic model that describes growth, death, and respiration of different taxa dependent on various environmental influence factors to estimate survival or extinction. Parameter and input uncertainty is propagated to model results. Such a model is needed to test our current quantitative understanding of ecosystem structure and function and to predict effects of anthropogenic impacts and restoration efforts. The model was tested using macroinvertebrate monitoring data from a catchment of the Swiss Plateau. Even without fitting model parameters, the model is able to represent key patterns of the coexistence structure of invertebrates at sites varying in external conditions (litter input, shading, water quality). This confirms the suitability of the model concept. More comprehensive testing and resulting model adaptations will further increase the predictive accuracy of the model.
Theoretical Hill-Type Muscle and Stability: Numerical Model and Application
S. Schmitt
2013-01-01
Full Text Available The construction of artificial muscles is one of the most challenging developments in today’s biomedical science. The application of artificial muscles is focused both on the construction of orthotics and prosthetics for rehabilitation and prevention purposes and on building humanoid walking machines for robotics research. Research in biomechanics tries to explain the functioning and design of real biological muscles and therefore lays the fundament for the development of functional artificial muscles. Recently, the hyperbolic Hill-type force-velocity relation was derived from simple mechanical components. In this contribution, this theoretical yet biomechanical model is transferred to a numerical model and applied for presenting a proof-of-concept of a functional artificial muscle. Additionally, this validated theoretical model is used to determine force-velocity relations of different animal species that are based on the literature data from biological experiments. Moreover, it is shown that an antagonistic muscle actuator can help in stabilising a single inverted pendulum model in favour of a control approach using a linear torque generator.
Prediction of the amount of urban waste solids by applying a gray theoretical model
无
2003-01-01
Urban waste solids are now becoming one of the most crucial environmental problems. There are several different kinds of technologies normally used for waste solids disposal, among which landfill is more favorable in China than others, especially for urban waste solids. Most of the design works up to now are based on a roughly estimation of the amount of urban waste solids without any theoretical support, which lead to a series problems. To meet the basic information requirements for the design work, the amount of the urban waste solids was predicted in this research by applying the gray theoretical model GM (1,1) through non-linear differential equation simulation. The model parameters were estimated with the least square method (LSM) by running a certain MATALAB program, and the hypothesis test results show that the residual between the prediction value and the actual value approximately comply with the normal distribution , and the probability of the residual within the range (-0.17, 0.19) is more than 95%, which indicate obviously that the model can be well used for the prediction of the amount of waste solids and those had been already testified by the latest two years data about the urban waste solids from Loudi City of China. With this model, the predicted amount of the waste solids produced in Loudi City in the next 30 years is 8049000 ton in total.
A P-value model for theoretical power analysis and its applications in multiple testing procedures
Fengqing Zhang
2016-10-01
Full Text Available Abstract Background Power analysis is a critical aspect of the design of experiments to detect an effect of a given size. When multiple hypotheses are tested simultaneously, multiplicity adjustments to p-values should be taken into account in power analysis. There are a limited number of studies on power analysis in multiple testing procedures. For some methods, the theoretical analysis is difficult and extensive numerical simulations are often needed, while other methods oversimplify the information under the alternative hypothesis. To this end, this paper aims to develop a new statistical model for power analysis in multiple testing procedures. Methods We propose a step-function-based p-value model under the alternative hypothesis, which is simple enough to perform power analysis without simulations, but not too simple to lose the information from the alternative hypothesis. The first step is to transform distributions of different test statistics (e.g., t, chi-square or F to distributions of corresponding p-values. We then use a step function to approximate each of the p-value’s distributions by matching the mean and variance. Lastly, the step-function-based p-value model can be used for theoretical power analysis. Results The proposed model is applied to problems in multiple testing procedures. We first show how the most powerful critical constants can be chosen using the step-function-based p-value model. Our model is then applied to the field of multiple testing procedures to explain the assumption of monotonicity of the critical constants. Lastly, we apply our model to a behavioral weight loss and maintenance study to select the optimal critical constants. Conclusions The proposed model is easy to implement and preserves the information from the alternative hypothesis.
Staub, Isabelle; Fredriksson, Anders; Outters, Nils [Golder Associates AB, Uppsala (Sweden)
2002-05-01
In the purpose of studying the possibilities of a Deep Repository for spent fuel, the Swedish Nuclear and Fuel Management Company (SKB) is currently planning for Site Investigations. Data collected from these Site Investigations are interpreted and analysed to achieve the full Site Description, which is built up of models from all the disciplines that are considered of importance for the Site Description. One of these models is the Rock Mechanical Descriptive Model,which would be developed for any site in hard crystalline rock, and is a combination and evaluation of the characterisation of rock mass by means of empirical relationships and a theoretical approach based on numerical modelling. The present report describes the theoretical approach. The characterisation of the mechanical properties of the rock mass, viewed as a unit consisting of intact rock and fractures, is achieved by numerical simulations with following input parameters: initial stresses, fracture geometry, distribution of rock mechanical properties, such as deformation and strength parameters, for the intact rock and for the fractures. The numerical modelling was performed with the two-dimensional code UDEC, and the rock block models were generated from 2D trace sections extracted from the 3D Discrete Fracture Network (DFN) model. Assumptions and uncertainties related to the set-up of the model are considered. The numerical model was set-up to simulate a plain strain-loading test. Different boundary conditions were applied on the model for simulating stress conditions (I) in the undisturbed rock mass, and (II) at the proximity of a tunnel. In order to assess the reliability of the model sensitivity analyses have been conducted on some rock block models for defining the dependency of mechanical properties to in situ stresses, the influence of boundary conditions, rock material and joint constitutive models used to simulate the behaviour of intact rock and fractures, domain size and anisotropy. To
Khalilian, Morteza; Navidbakhsh, Mahdi; Valojerdi, Mojtaba Rezazadeh; Chizari, Mahmoud; Yazdi, Poopak Eftekhari
2010-04-06
The zona pellucida (ZP) is the spherical layer that surrounds the mammalian oocyte. The physical hardness of this layer plays a crucial role in fertilization and is largely unknown because of the lack of appropriate measuring and modelling methods. The aim of this study is to measure the biomechanical properties of the ZP of human/mouse ovum and to test the hypothesis that Young's modulus of the ZP varies with fertilization. Young's moduli of ZP are determined before and after fertilization by using the micropipette aspiration technique, coupled with theoretical models of the oocyte as an elastic incompressible half-space (half-space model), an elastic compressible bilayer (layered model) or an elastic compressible shell (shell model). Comparison of the models shows that incorporation of the layered geometry of the ovum and the compressibility of the ZP in the layered and shell models may provide a means of more accurately characterizing ZP elasticity. Evaluation of results shows that although the results of the models are different, all confirm that the hardening of ZP will increase following fertilization. As can be seen, different choices of models and experimental parameters can affect the interpretation of experimental data and lead to differing mechanical properties.
The coupled effects of carbon and nitrogen on soil decomposition: A theoretical model
Darby, B.; Finzi, A.
2013-12-01
Soil organic matter (SOM) plays a crucial role in the carbon (C) cycle, holding 2.5 times more carbon than plant biomass. Ecosystem models predict that climate warming will stimulate decomposition of soil carbon stocks, in turn leading to positive feedbacks on warming. Recent empirical studies and modeling work has revealed the importance of microbial physiology and exoenzyme kinetics in driving SOM decomposition. Existing mathematical models describe the microbial processes and biophysics involved in the decomposition. However, although decomposition by nitrogen-degrading enzymes is included in some models, nitrogen (N) does not drive model behavior and there are no reaction kinetics associated with the depolymerization or uptake of N. Additionally, very few empirically measured kinetic values exist for N-degrading enzymes or the uptake of N by microbes. This study proposes a theoretical model of SOM decomposition based on the principles of exoenzyme kinetics and microbial biophysics that explicitly links C and N through microbial uptake and SOM decomposition kinetics and by placing stoichiometric constraints on microbial growth and exoenzyme production. After constructing the model framework, the model was then used to test soil-carbon responses to warming, and to explore the importance of N uptake and depolymerization kinetics in driving decomposition. The model predictions suggest that the response of kinetics to temperature are more important than microbial responses in determining decomposition rates. Additionally, variations in the kinetics of N depolymerization affected decomposition rates, whereas N uptake kinetics and their effect on enzyme production had almost no effect. The model outputs were also compared to a C-only model framework in order to assess the effects of N on model behavior. The incorporation of N into a SOM decomposition model produced different, and in some cases, contradictory results as compared to a C-only model. Overall, these
Ursino, Mauro; Cuppini, Cristiano; Magosso, Elisa
2017-03-01
Recent theoretical and experimental studies suggest that in multisensory conditions, the brain performs a near-optimal Bayesian estimate of external events, giving more weight to the more reliable stimuli. However, the neural mechanisms responsible for this behavior, and its progressive maturation in a multisensory environment, are still insufficiently understood. The aim of this letter is to analyze this problem with a neural network model of audiovisual integration, based on probabilistic population coding-the idea that a population of neurons can encode probability functions to perform Bayesian inference. The model consists of two chains of unisensory neurons (auditory and visual) topologically organized. They receive the corresponding input through a plastic receptive field and reciprocally exchange plastic cross-modal synapses, which encode the spatial co-occurrence of visual-auditory inputs. A third chain of multisensory neurons performs a simple sum of auditory and visual excitations. The work includes a theoretical part and a computer simulation study. We show how a simple rule for synapse learning (consisting of Hebbian reinforcement and a decay term) can be used during training to shrink the receptive fields and encode the unisensory likelihood functions. Hence, after training, each unisensory area realizes a maximum likelihood estimate of stimulus position (auditory or visual). In cross-modal conditions, the same learning rule can encode information on prior probability into the cross-modal synapses. Computer simulations confirm the theoretical results and show that the proposed network can realize a maximum likelihood estimate of auditory (or visual) positions in unimodal conditions and a Bayesian estimate, with moderate deviations from optimality, in cross-modal conditions. Furthermore, the model explains the ventriloquism illusion and, looking at the activity in the multimodal neurons, explains the automatic reweighting of auditory and visual inputs
de Barros, F P J; Fiori, A; Boso, F; Bellin, A
2015-01-01
Spatial heterogeneity of the hydraulic properties of geological porous formations leads to erratically shaped solute clouds, thus increasing the edge area of the solute body and augmenting the dilution rate. In this study, we provide a theoretical framework to quantify dilution of a non-reactive solute within a steady state flow as affected by the spatial variability of the hydraulic conductivity. Embracing the Lagrangian concentration framework, we obtain explicit semi-analytical expressions for the dilution index as a function of the structural parameters of the random hydraulic conductivity field, under the assumptions of uniform-in-the-average flow, small injection source and weak-to-mild heterogeneity. Results show how the dilution enhancement of the solute cloud is strongly dependent on both the statistical anisotropy ratio and the heterogeneity level of the porous medium. The explicit semi-analytical solution also captures the temporal evolution of the dilution rate; for the early- and late-time limits, the proposed solution recovers previous results from the literature, while at intermediate times it reflects the increasing interplay between large-scale advection and local-scale dispersion. The performance of the theoretical framework is verified with high resolution numerical results and successfully tested against the Cape Cod field data.
Hunault, C C; Habbema, J D F; Eijkemans, M J C; Collins, J A; Evers, J L H; te Velde, E R
2004-09-01
Several models have been published for the prediction of spontaneous pregnancy among subfertile patients. The aim of this study was to broaden the empirical basis for these predictions by making a synthesis of three previously published models. We used the original data from the studies of Eimers et al. (1994), Collins et al. (1995) and Snick et al. (1997) on couples consulting for various forms of subfertility. We developed a so-called three-sample synthesis model for predicting spontaneous conception leading to live birth within 1 year after intake based on the three data sets. The predictors used are duration of subfertility, women's age, primary or secondary infertility, percentage of motile sperm, and whether the couple was referred by a general practitioner or by a gynaecologist (referral status). The performance of this model was assessed according to a 'jack-knife' analysis. Because the post-coital test (PCT) was not assessed in one of the samples, a synthesis model including the PCT was based on two samples only. The ability of the synthesis models to distinguish between women who became pregnant and those who did not was comparable to the ability of the one-sample models when applied in the other samples. The reliability of the predictions by the three-sample synthesis model was somewhat better. Predictions improved considerably by including the PCT. The synthesis models performed better and had a broader empirical basis than the original models. They are therefore better suitable for application in other centres.
Observation and theoretic analysis of gas-bubble formation and growth in water-model
WU Rui-zhi; SHU Da; SUN Bao-de; WANG Jun; LU Yan-ling
2005-01-01
The behavior of bubbles is observed with high-speed digital camera in water-model. It is found that each bubble has three processes: bubble formation, bubble coalescence and bubble division. Bubble shape is spherical firstly, then elliptical and spherical crown after coalescence, and spherical again after division. These phenomena are explained theoretically. And the bubble size is defined newly. The so-defined bubble size is measured through digital camera and LECO graphical analyzer. And the measured results are compared with those in literatures.
Semileptonic ( → ) decay in a ﬁeld theoretic quark model
R K Das; A R Panda; R K Sahoo; M R Swain
2002-03-01
The semileptonic decay width of heavy baryons such as ( → ) has been estimated in the framework of a nonrelativistic ﬁeld theoretic quark model where four component quark ﬁeld operators along with a harmonic oscillator wave function are used to describe translationally invariant hadronic states. The present estimation does not make an explicit use of heavy quark symmetry and has a reasonable agreement with the experimentally measured decay width, polarisation ratio and form factors with the harmonic oscillator radii and quark momentum distribution inside the hadron as free parameters.
Theoretical model study of dynamic ferromagnetic susceptibility in mono-layer graphene
Sahu, Sivabrata; Parashar, S. K. S.; Rout, G. C.
2016-04-01
We report here a microscopic theoretical study of dynamic ferromagnetic spin susceptibility of electrons for graphene systems, which deal with a tight-binding model Hamiltonian consisting of the hopping of electrons up to third-nearest-neighbors, impurity and substrate effects besides Coulomb interaction of electrons at A-and B- sub- lattices. The spin susceptibility involves four two-particle Green's functions, which are calculated by Zubarev's Green's function technique. The up and down electron occupancies at A and B sub-lattices are computed numerically and self-consistently. The temperature dependent susceptibility shows a pronounced peak at Curie temperature for critical Coulomb interaction Uc = 2.2t1.
Microscopic theoretical model study of band gap opening in AA-stacked bi-layer graphene
Sahu, Sivabrata; Parashar, S. K. S.; Rout, G. C.
2016-05-01
We address here a tight-binding theoretical model calculation for AA-stacked bi-layer graphene taking into account of a biased potential between two layers to study the density of states and the band dispersion within the total Brillouin zone. We have calculated the electronic Green's function for electron operator corresponding to A and B sub lattices by Zubarev's Green's function technique from which the electronic density of states and the electron band energy dispersion are calculated. The numerically computed density of states and band energy dispersions are investigated by tuning the biased potential to exhibit the band gap by varying the different physical parameters.
Theoretical Model of Software Process Improvement for CMM and CMMI based on QFD
Yonghui Cao
2013-01-01
Full Text Available In this paper, we first introduce Software Process Improvement (SPI and Quality Function Deployment (QFD; then study theoretical model of SPI for CMM and CMMI based on QFD. Through the research, we hope to achieve three goals: first, to develop a method, based on QFD, for the integration and prioritization of requirements from multiple perspectives; second, to map process requirements, including business requirements, to CMM or CMMI with the help of QFD; third, to be able to prioritize software process improvement actions based on process requirements. Finally, we also draw conclusions.
The lack of theoretical support for using person trade-offs in QALY-type models
Østerdal, Lars Peter Raahave
2009-01-01
Considerable support for the use of person trade-off methods to assess the quality-adjustment factor in quality-adjusted life years (QALY) models has been expressed in the literature. The WHO has occasionally used similar methods to assess the disability weights for calculation of disability......-adjusted life years (DALYs). This paper discusses the theoretical support for the use of person trade-offs in QALY-type measurement of (changes in) population health. It argues that measures of this type based on such quality-adjustment factors almost always violate the Pareto principle, and so lack normative...
Construction of a Dejourian theoretic model for the worker’s health evaluation
Marilise Katsurayama
2012-09-01
Full Text Available Objective: To construct a theoretical model intended for evaluative researches on the worker’s health into the Family Health Strategy, supported by Christophe Dejours’s theory. Methods: The theoretical model was built between September and December 2010, through the integration of Dejours’s theory and the facts, the current situation of health workers, represented by official documents, which allowed the instrumentalization of thought, making affordable the features related to worker’s health. Results: Dejourian theory was adopted as the basic element in the construction of this model, due to its approach to the dynamics of the mental processes involved in the confrontation between the subject and his reality in work, focusing the interest in the worker’s subjective experiences (main source of pleasure and suffering in work. Given the influence played by the work organization on the worker’s health, it becomes essential to perform the analysis of the variables that influence pleasure-suffering process among these actors of such an importance for the health practices that reorganize the primary care. Conclusion: Christophe Dejours’s theory reveals its great potential for the analysis of the psychological processes involved in the confrontation between the worker in primary care and his reality, since it is vital to understand how the issues related to work in health area are disclosed, and the way the worker shall react to difficult work situations.
Multi-Nucleon Short-Range Correlation Model for Nuclear Spectral Functions: I. Theoretical Framework
Artiles, Oswaldo
2016-01-01
We develop a theoretical approach for nuclear spectral functions at high missing momenta and removal energy based on the multi-nucleon short-range correlation~(SRC) model. The approach is based on the effective Feynman diagrammatic method which allows to account for the relativistic effects important in the SRC domain. In addition to two-nucleon SRC with center of mass motion we derived also the contribution of three-nucleon SRCs to the nuclear spectral functions. The latter is modeled based on the assumption that 3N SRCs are a product of two sequential short range NN interactions. This approach allowed us to express the 3N SRC part of the nuclear spectral function as a convolution of two NN SRCs. Thus the knowledge of 2N SRCs allows us to model both two- and three-nucleon SRC contribution to the spectral function. The derivations of the spectral functions are based on the two theoretical frameworks in evaluating covariant Feynman diagrams: In the first, referred as virtual nucleon approximation, we reduce Fe...
Rütten, A; Röger, U; Abu-Omar, K; Frahsa, A
2009-09-01
Models explaining the engagement of organizations in different policy sectors in health promotion policy implementation often utilize retrospective data. The current study attempted to model determinants of organizational readiness (goals, resources, obligation, opportunities) in supporting health policy implementation prospectively. Twenty qualitative interviews with representatives of organizations from different policy sectors, levels of government and organizational legal entities were conducted at the beginning of a project for the promotion of physical activity among women in difficult life situations. Organizational support in developing, implementing and disseminating the project was documented over 36 months. Results indicated that in most organizations, determinants were not favorable for health promotion policy action for physical activity among women in difficult life situations. Six organizations did not report any favorable determinant, and two organizations reported four. The other 12 organizations reported positive results for some of the determinants. Project work received support from 6 out of the 20 organizations. A case study of three organizations indicated that engagement or disengagement of organizations in health promotion policy actions might be partly explained by the theoretical model. The prospective assessment of organizational readiness in implementing health promotion policy is highly relevant for health promotion. Considering the proposed theoretical framework may aid in advancing our understanding of factors that are related to organizational engagement in health promotion actions.
The neural mediators of kindness-based meditation: a theoretical model
Jennifer Streiffer Mascaro
2015-02-01
Full Text Available Although kindness-based contemplative practices are increasingly employed by clinicians and cognitive researchers to enhance prosocial emotions, social cognitive skills, and well-being, and as a tool to understand the basic workings of the social mind, we lack a coherent theoretical model with which to test the mechanisms by which kindness-based meditation may alter the brain and body. Here we link contemplative accounts of compassion and loving-kindness practices with research from social cognitive neuroscience and social psychology to generate predictions about how diverse practices may alter brain structure and function and related aspects of social cognition. Contingent on the nuances of the practice, kindness-based meditation may enhance the neural systems related to faster and more basic perceptual or motor simulation processes, simulation of another’s affective body state, slower and higher-level perspective-taking, modulatory processes such as emotion regulation and self/other discrimination, and combinations thereof. This theoretical model will be discussed alongside best practices for testing such a model and potential implications and applications of future work.
G. J. Pelgrim
2016-01-01
Full Text Available Technological advances in magnetic resonance imaging (MRI and computed tomography (CT, including higher spatial and temporal resolution, have made the prospect of performing absolute myocardial perfusion quantification possible, previously only achievable with positron emission tomography (PET. This could facilitate integration of myocardial perfusion biomarkers into the current workup for coronary artery disease (CAD, as MRI and CT systems are more widely available than PET scanners. Cardiac PET scanning remains expensive and is restricted by the requirement of a nearby cyclotron. Clinical evidence is needed to demonstrate that MRI and CT have similar accuracy for myocardial perfusion quantification as PET. However, lack of standardization of acquisition protocols and tracer kinetic model selection complicates comparison between different studies and modalities. The aim of this overview is to provide insight into the different tracer kinetic models for quantitative myocardial perfusion analysis and to address typical implementation issues in MRI and CT. We compare different models based on their theoretical derivations and present the respective consequences for MRI and CT acquisition parameters, highlighting the interplay between tracer kinetic modeling and acquisition settings.
A Theoretical Model for Understanding the Dynamics of Online Social Networks Decay
Abufouda, Mohammed
2016-01-01
Online social networks represent a main source of communication and information exchange in today's life. They facilitate exquisitely news sharing, knowledge elicitation, and forming groups of same interests. Researchers in the last two decades studied the growth dynamics of the online social networks extensively questing a clear understanding of the behavior of humans in online social networks that helps in many directions, like engineering better recommendation systems and attracting new members. However, not all of social networks achieved the desired growth, for example, online social networks like MySpace, Orkut, and Friendster are out of service today. In this work, we present a probabilistic theoretical model that captures the dynamics of the social decay due to the inactivity of the members of a social network. The model is proved to have some interesting mathematical properties, namely \\textit{submodularity}, which imply achieving the model optimization in a reasonable performance. That means the max...
B → K∗ ℓ + ℓ - decays at large recoil in the Standard Model: a theoretical reappraisal
Ciuchini, Marco; Fedele, Marco; Franco, Enrico; Mishima, Satoshi; Paul, Ayan; Silvestrini, Luca; Valli, Mauro
2016-06-01
We critically reassess the theoretical uncertainties in the Standard Model calculation of the B → K ∗ ℓ + ℓ - observables, focusing on the low q 2 region. We point out that even optimized observables are affected by sizable uncertainties, since hadronic contributions generated by current-current operators with charm are difficult to estimate, especially for q 2 ˜ 4 m c 2 ≃ 6.8 GeV2. We perform a detailed numerical analysis and present both predictions and results from the fit obtained using most recent data. We find that non-factorizable power corrections of the expected order of magnitude are sufficient to give a good description of current experimental data within the Standard Model. We discuss in detail the q 2 dependence of the corrections and their possible interpretation as shifts of the Standard Model Wilson coefficients.
Purdy, J G
1975-01-01
An investigation is made into the subject of scoring tables for track and field with emphasis on the application of computers to calculate and output the tables. The resulting scoring tables represent an attempt to describe the effective quality of performance for track and field events. This paper is published in three parts. The first portion reviewed the historical development of scoring tables. This part concerns the theoretical foundation and development of a mathematical model. A set of underlying principles and construction guidelines are established as a basis for all scoring tables. In order to satisfy the goals, a model which includes an exponential term is developed. The concept of a zero offset is introduced as a boundary value for the low-level performances. The final part concerns an evaluation of the model and an analysis of the point scores for different events.
Theoretical analysis of electronic absorption spectra of vitamin B12 models
Andruniow, Tadeusz; Kozlowski, Pawel M.; Zgierski, Marek Z.
2001-10-01
Time-dependent density-functional theory (TD-DFT) is applied to analyze the electronic absorption spectra of vitamin B12. To accomplish this two model systems were considered: CN-[CoIII-corrin]-CN (dicyanocobinamide, DCC) and imidazole-[CoIII-corrin]-CN (cyanocobalamin, ImCC). For both models 30 lowest excited states were calculated together with transition dipole moments. When the results of TD-DFT calculations were directly compared with experiment it was found that the theoretical values systematically overestimate experimental data by approximately 0.5 eV. The uniform adjustment of the calculated transition energies allowed detailed analysis of electronic absorption spectra of vitamin B12 models. All absorption bands in spectral range 2.0-5.0 eV were readily assigned. In particular, TD-DFT calculations were able to explain the origin of the shift of the lowest absorption band caused by replacement of the-CN axial ligand by imidazole.
Activity systems modeling as a theoretical lens for social exchange studies
Ernest Jones
2016-01-01
Full Text Available The social exchange perspective seeks to acknowledge, understand and predict the dynamics of social interactions. Empirical research involving social exchange constructs have grown to be highly technical including confirmatory factor analysis to assess construct distinctiveness and structural equation modeling to assess construct causality. Each study seemingly strives to assess how underlying social exchange theoretic constructs interrelate. Yet despite this methodological depth and resultant explanatory and predictive power, a significant number of studies report findings that, once synthesized, suggest an underlying persistent threat of conceptual or construct validity brought about by a search for epistemological parsimony. Further, it is argued that a methodological approach that embraces inherent complexity such as activity systems modeling facilitates the search for simplified models while not ignoring contextual factors.
Milad Elyasi
2014-04-01
Full Text Available In the recent decade, studying the economic order quantity (EOQ models with imperfect quality has appealed to many researchers. Only few papers are published discussing EOQ models with imperfect items in a supply chain. In this paper, a two-echelon decentralized supply chain consisting of a manufacture and a supplier that both face just in time (JIT inventory problem is considered. It is sought to find the optimal number of the shipments and the quantity of each shipment in a way that minimizes the both manufacturer’s and the supplier’s cost functions. To the authors’ best knowledge, this is the first paper that deals with imperfect items in a decentralized supply chain. Thereby, three different game theoretical solution approaches consisting of two non-cooperative games and a cooperative game are proposed. Comparing the results of three different scenarios with those of the centralized model, the conclusions are drawn to obtain the best approach.
Theoretical Model for the Formation of Caveolae and Similar Membrane Invaginations
Sens, Pierre; Turner, Matthew S.
2004-01-01
We study a physical model for the formation of bud-like invaginations on fluid lipid membranes under tension, and apply this model to caveolae formation. We demonstrate that budding can be driven by membrane-bound proteins, provided that they exert asymmetric forces on the membrane that give rise to bending moments. In particular, caveolae formation does not necessarily require forces to be applied by the cytoskeleton. Our theoretical model is able to explain several features observed experimentally in caveolae, where proteins in the caveolin family are known to play a crucial role in the formation of caveolae buds. These include 1), the formation of caveolae buds with sizes in the 100-nm range and 2), that certain N- and C-termini deletion mutants result in vesicles that are an order-of-magnitude larger. Finally, we discuss the possible origin of the morphological striations that are observed on the surfaces of the caveolae. PMID:15041647
Dodd, Bucky J.
2013-01-01
Online course design is an emerging practice in higher education, yet few theoretical models currently exist to explain or predict how the diffusion of innovations occurs in this space. This study used a descriptive, quantitative survey research design to examine theoretical relationships between decision-making style and resistance to change…
Dodd, Bucky J.
2013-01-01
Online course design is an emerging practice in higher education, yet few theoretical models currently exist to explain or predict how the diffusion of innovations occurs in this space. This study used a descriptive, quantitative survey research design to examine theoretical relationships between decision-making style and resistance to change…
Petrov, Blagovest; Vink, Jorick S.; Gräfener, Götz
2016-05-01
Luminous blue variables (LBVs) have been suggested to be the direct progenitors of supernova Types IIb and IIn, with enhanced mass loss prior to explosion. However, the mechanism of this mass loss is not yet known. Here, we investigate the qualitative behaviour of theoretical stellar wind mass loss as a function of Teff across two bi-stability jumps in blue supergiant regime and also in proximity to the Eddington limit, relevant for LBVs. To investigate the physical ingredients that play a role in the radiative acceleration we calculate blue supergiant wind models with the CMFGEN non-local thermodynamic equilibrium model atmosphere code over an effective temperature range between 30 000 and 8800 K. Although our aim is not to provide new mass-loss rates for BA supergiants, we study and confirm the existence of two bi-stability jumps in mass-loss rates predicted by Vink et al. However, they are found to occur at somewhat lower Teff (20 000 and 9000 K, respectively) than found previously, which would imply that stars may evolve towards lower Teff before strong mass loss is induced by the bi-stability jumps. When the combined effects of the second bi-stability jump and the proximity to Eddington limit are accounted for, we find a dramatic increase in the mass-loss rate by up to a factor of 30. Further investigation of both bi-stability jumps is expected to lead to a better understanding of discrepancies between empirical modelling and theoretical mass-loss rates reported in the literature, and to provide key inputs for the evolution of both normal AB supergiants and LBVs, as well as their subsequent supernova Type II explosions.
Hanuschkin, A; Ganguli, S; Hahnloser, R H R
2013-01-01
Mirror neurons are neurons whose responses to the observation of a motor act resemble responses measured during production of that act. Computationally, mirror neurons have been viewed as evidence for the existence of internal inverse models. Such models, rooted within control theory, map-desired sensory targets onto the motor commands required to generate those targets. To jointly explore both the formation of mirrored responses and their functional contribution to inverse models, we develop a correlation-based theory of interactions between a sensory and a motor area. We show that a simple eligibility-weighted Hebbian learning rule, operating within a sensorimotor loop during motor explorations and stabilized by heterosynaptic competition, naturally gives rise to mirror neurons as well as control theoretic inverse models encoded in the synaptic weights from sensory to motor neurons. Crucially, we find that the correlational structure or stereotypy of the neural code underlying motor explorations determines the nature of the learned inverse model: random motor codes lead to causal inverses that map sensory activity patterns to their motor causes; such inverses are maximally useful, by allowing the imitation of arbitrary sensory target sequences. By contrast, stereotyped motor codes lead to less useful predictive inverses that map sensory activity to future motor actions. Our theory generalizes previous work on inverse models by showing that such models can be learned in a simple Hebbian framework without the need for error signals or backpropagation, and it makes new conceptual connections between the causal nature of inverse models, the statistical structure of motor variability, and the time-lag between sensory and motor responses of mirror neurons. Applied to bird song learning, our theory can account for puzzling aspects of the song system, including necessity of sensorimotor gating and selectivity of auditory responses to bird's own song (BOS) stimuli.
Alexander eHanuschkin
2013-06-01
Full Text Available Mirror neurons are neurons whose responses to the observation of a motor act resemble responses measured during production of that act. Computationally, mirror neurons have been viewed as evidence for the existence of internal inverse models. Such models, rooted within control theory, map desired sensory targets onto the motor commands required to generate those targets. To jointly explore both the formation of mirrored responses and their functional contribution to inverse models, we develop a correlation-based theory of interactions between a sensory and a motor area. We show that a simple eligibility-weighted Hebbian learning rule, operating within a sensorimotor loop during motor explorations and stabilized by heterosynaptic competition, naturally gives rise to mirror neurons as well as control theoretic inverse models encoded in the synaptic weights from sensory to motor neurons. Crucially, we find that the correlational structure or stereotypy of the neural code underlying motor explorations determines the nature of the learned inverse model: Random motor codes lead to causal inverses that map sensory activity patterns to their motor causes; such inverses are maximally useful, they allow for imitating arbitrary sensory target sequences. By contrast, stereotyped motor codes lead to less useful predictive inverses that map sensory activity to future motor actions.Our theory generalizes previous work on inverse models by showing that such models can be learned in a simple Hebbian framework without the need for error signals or backpropagation, and it makes new conceptual connections between the causal nature of inverse models, the statistical structure of motor variability, and the time-lag between sensory and motor responses of mirror neurons. Applied to bird song learning, our theory can account for puzzling aspects of the song system, including necessity of sensorimotor gating and selectivity of auditory responses to bird’s own song
The custodially protected Randall-Sundrum model. Theoretical aspects and flavour phenomenology
Blanke, Monika
2009-07-24
Models with a warped extra dimension, so-called Randall-Sundrum models, provide an appealing solution to the gauge and flavour hierarchy problems of the Standard Model. After introducing the theoretical basics of such models, we concentrate on a specific model whose symmetry structure is extended to protect the T parameter and the Zb{sub L} anti b{sub L} coupling from large corrections. We introduce the basic action and discuss in detail effects of electroweak symmetry breaking and the flavour structure of the model. Then we analyse meson-antimeson mixing and rare decays that are affected by new tree level contributions from the Kaluza-Klein modes of the gauge bosons and from the Z boson in an important manner. After deriving analytic expressions for the most important K and B physics observables, we perform a global numerical analysis of the new effects in the model in question. We confirm the recent findings that a stringent constraint on the model is placed by CP-violation in K{sup 0} - anti K{sup 0} mixing. However, even for Kaluza-Klein particles in the reach of the LHC an agreement with all available data can be obtained without significant fine-tuning. We find possible large effects in either CP-violating effects in the B{sub s} - anti B{sub s} system or in the rare K decays, but not simultaneously. In any case the deviations from the Standard Model predictions in the rare B decays are small and difficult to measure. The specific pattern of new flavour effects allows to distinguish this model from other New Physics frameworks, which we demonstrate explicitly for the case of models with Minimal Flavour Violation and for the Littlest Higgs model with T-parity. (orig.)
The Safety Culture Enactment Questionnaire (SCEQ): Theoretical model and empirical validation.
de Castro, Borja López; Gracia, Francisco J; Tomás, Inés; Peiró, José M
2017-06-01
This paper presents the Safety Culture Enactment Questionnaire (SCEQ), designed to assess the degree to which safety is an enacted value in the day-to-day running of nuclear power plants (NPPs). The SCEQ is based on a theoretical safety culture model that is manifested in three fundamental components of the functioning and operation of any organization: strategic decisions, human resources practices, and daily activities and behaviors. The extent to which the importance of safety is enacted in each of these three components provides information about the pervasiveness of the safety culture in the NPP. To validate the SCEQ and the model on which it is based, two separate studies were carried out with data collection in 2008 and 2014, respectively. In Study 1, the SCEQ was administered to the employees of two Spanish NPPs (N=533) belonging to the same company. Participants in Study 2 included 598 employees from the same NPPs, who completed the SCEQ and other questionnaires measuring different safety outcomes (safety climate, safety satisfaction, job satisfaction and risky behaviors). Study 1 comprised item formulation and examination of the factorial structure and reliability of the SCEQ. Study 2 tested internal consistency and provided evidence of factorial validity, validity based on relationships with other variables, and discriminant validity between the SCEQ and safety climate. Exploratory Factor Analysis (EFA) carried out in Study 1 revealed a three-factor solution corresponding to the three components of the theoretical model. Reliability analyses showed strong internal consistency for the three scales of the SCEQ, and each of the 21 items on the questionnaire contributed to the homogeneity of its theoretically developed scale. Confirmatory Factor Analysis (CFA) carried out in Study 2 supported the internal structure of the SCEQ; internal consistency of the scales was also supported. Furthermore, the three scales of the SCEQ showed the expected correlation
Modeling of air-gap membrane distillation process: A theoretical and experimental study
Alsaadi, Ahmad Salem
2013-06-03
A one dimensional (1-D) air gap membrane distillation (AGMD) model for flat sheet type modules has been developed. This model is based on mathematical equations that describe the heat and mass transfer mechanisms of a single-stage AGMD process. It can simulate AGMD modules in both co-current and counter-current flow regimes. The theoretical model was validated using AGMD experimental data obtained under different operating conditions and parameters. The predicted water vapor flux was compared to the flux measured at five different feed water temperatures, two different feed water salinities, three different air gap widths and two MD membranes with different average pore sizes. This comparison showed that the model flux predictions are strongly correlated with the experimental data, with model predictions being within +10% of the experimentally determined values. The model was then used to study and analyze the parameters that have significant effect on scaling-up the AGMD process such as the effect of increasing the membrane length, and feed and coolant flow rates. The model was also used to analyze the maximum thermal efficiency of the AGMD process by tracing changes in water production rate and the heat input to the process along the membrane length. This was used to understand the gain in both process production and thermal efficiency for different membrane surface areas and the resultant increases in process capital and water unit cost. © 2013 Elsevier B.V.
A theoretical model for predicting the Peak Cutting Force of conical picks
Gao Kuidong
2014-01-01
Full Text Available In order to predict the PCF (Peak Cutting Force of conical pick in rock cutting process, a theoretical model is established based on elastic fracture mechanics theory. The vertical fracture model of rock cutting fragment is also established based on the maximum tensile criterion. The relation between vertical fracture angle and associated parameters (cutting parameter and ratio B of rock compressive strength to tensile strength is obtained by numerical analysis method and polynomial regression method, and the correctness of rock vertical fracture model is verified through experiments. Linear regression coefficient between the PCF of prediction and experiments is 0.81, and significance level less than 0.05 shows that the model for predicting the PCF is correct and reliable. A comparative analysis between the PCF obtained from this model and Evans model reveals that the result of this prediction model is more reliable and accurate. The results of this work could provide some guidance for studying the rock cutting theory of conical pick and designing the cutting mechanism.
Evans, Jason; Sullivan, Jack
2011-01-01
A priori selection of models for use in phylogeny estimation from molecular sequence data is increasingly important as the number and complexity of available models increases. The Bayesian information criterion (BIC) and the derivative decision-theoretic (DT) approaches rely on a conservative approximation to estimate the posterior probability of a given model. Here, we extended the DT method by using reversible jump Markov chain Monte Carlo approaches to directly estimate model probabilities for an extended candidate pool of all 406 special cases of the general time reversible + Γ family. We analyzed 250 diverse data sets in order to evaluate the effectiveness of the BIC approximation for model selection under the BIC and DT approaches. Model choice under DT differed between the BIC approximation and direct estimation methods for 45% of the data sets (113/250), and differing model choice resulted in significantly different sets of trees in the posterior distributions for 26% of the data sets (64/250). The model with the lowest BIC score differed from the model with the highest posterior probability in 30% of the data sets (76/250). When the data indicate a clear model preference, the BIC approximation works well enough to result in the same model selection as with directly estimated model probabilities, but a substantial proportion of biological data sets lack this characteristic, which leads to selection of underparametrized models.
A THEORETICAL MODEL OF SOCIO-PSYCHOLOGICAL SUPPORT WORK PROCESSES FOR MANAGEMENT OF PRODUCTION TEAM
Tatyana Gennadevna Pronyushkina
2015-10-01
Full Text Available This article discusses the management of production team, in particular the developed theoretical model of socio-psychological support work processes for management of production team. The author of the research are formulated the purpose and objectives of social-psychological work on management of the production team. Developed in the study a theoretical model aimed at determining the conditions and the identification of features of effective management of the enterprise taking into account the socio-psychological characteristics of its staff. Tasks include: definition of the main characteristics of the production team and their severity, the analysis of these characteristics and identifying opportunities for their transformation, development of recommendations for management of social-psychological work on effects on the characteristics of the collective enterprise.Practical study of the activities of a number of businesses have shown the need to improve socio-psychological support of management processes production team: introducing a social and psychological planning team and develop the practice of sociological research on the state of the team, to ensure the smoothing of relations between workers and management through periodic meetings, creations of conditions for feedback, maintaining healthy competition among team members.
Ultraviolet Properties of Primeval Galaxies: Theoretical Models from Stellar Population Synthesis
Buzzoni, Alberto
2002-03-01
The ultraviolet luminosity evolution of star-forming galaxies is explored from the theoretical point of view, especially focusing on the theory of UV energetics in simple and composite stellar populations and its relationship to the star formation rate and other main evolutionary parameters. Galaxy emission below λ<3000 Å directly correlates with actual star formation, not depending on the total mass of the system. A straightforward calibration is obtained, in this sense, from the theoretical models at 1600, 2000, and 2800 Å, and a full comparison is carried out with IUE data and other balloon-borne observations for local galaxies. The claimed role of late-type systems as prevailing contributors to the cosmic UV background is reinforced by our results; at 2000 Å, Im irregulars are found in fact nearly 4 orders of magnitude brighter than ellipticals, per unit luminous mass. The role of dust absorption in the observation of high-redshift galaxies is assessed, comparing the model output and observed spectral energy distribution of local galaxy samples. Similar to what we observe in our own galaxy, a quick evolution in the dust environment might be envisaged in primeval galaxies, with an increasing fraction of luminous matter that would escape the regions of harder and ``clumpy'' dust absorption on a timescale of some 107 yr, comparable to the lifetime of stars of 5-10 Msolar.
Berezovska, Ganna; Mostarda, Stefano; Rao, Francesco
2012-01-01
Molecular simulations as well as single molecule experiments have been widely analyzed in terms order parameters, the latter representing candidate probes for the relevant degrees of freedom. Notwithstanding this approach is very intuitive, mounting evidence showed that such description is not accurate, leading to ambiguous definitions of states and wrong kinetics. To overcome these limitations a framework making use of order parameter fluctuations in conjunction with complex network analysis is investigated. Derived from recent advances in the analysis of single molecule time traces, this approach takes into account of the fluctuations around each time point to distinguish between states that have similar values of the order parameter but different dynamics. Snapshots with similar fluctuations are used as nodes of a transition network, the clusterization of which into states provides accurate Markov-State-Models of the system under study. Application of the methodology to theoretical models with a noisy orde...
A unified theoretical framework for mapping models for the multi-state Hamiltonian.
Liu, Jian
2016-11-28
We propose a new unified theoretical framework to construct equivalent representations of the multi-state Hamiltonian operator and present several approaches for the mapping onto the Cartesian phase space. After mapping an F-dimensional Hamiltonian onto an F+1 dimensional space, creation and annihilation operators are defined such that the F+1 dimensional space is complete for any combined excitation. Commutation and anti-commutation relations are then naturally derived, which show that the underlying degrees of freedom are neither bosons nor fermions. This sets the scene for developing equivalent expressions of the Hamiltonian operator in quantum mechanics and their classical/semiclassical counterparts. Six mapping models are presented as examples. The framework also offers a novel way to derive such as the well-known Meyer-Miller model.
Volumetric Properties of Chloroalkanes + Amines Mixtures: Theoretical Analysis Using the ERAS-Model
Tôrres, R. B.; Hoga, H. E.; Magalhães, J. G.; Volpe, P. L. O.
2009-08-01
In this study, experimental data of excess molar volumes of {dichloromethane (DCM), or trichloromethane (TCM) + n-butylamine (n-BA), or +s-butylamine (s-BA), or +t-butylamine (t-BA), or +diethylamine (DEA), or +triethylamine (TEA)} mixtures as a function of composition have been used to test the applicability of the extended real associated solution model (ERAS-Model). The values of the excess molar volume were negative for (DCM + t-BA, or +DEA, or +TEA and TCM + n-BA, or +s-BA, or +DEA, or +TEA) mixtures and present sigmoid curves for (DCM + n-BA, or +s-BA) mixtures over the complete mole-fraction range. The agreement between theoretical and experimental results is discussed in terms of cross-association between the components present in the mixtures.
From moral theory to penal attitudes and back: a theoretically integrated modeling approach.
de Keijser, Jan W; van der Leeden, Rien; Jackson, Janet L
2002-01-01
From a moral standpoint, we would expect the practice of punishment to reflect a solid and commonly shared legitimizing framework. Several moral legal theories explicitly aim to provide such frameworks. Based on the theories of Retributivism, Utilitarianism, and Restorative Justice, this article first sets out to develop a theoretically integrated model of penal attitudes and then explores the extent to which Dutch judges' attitudes to punishment fit the model. Results indicate that penal attitudes can be measured in a meaningful way that is consistent with an integrated approach to moral theory. The general structure of penal attitudes among Dutch judges suggests a streamlined and pragmatic approach to legal punishment that is identifiably founded on the separate concepts central to moral theories of punishment. While Restorative Justice is frequently presented as an alternative paradigm, results show it to be smoothly incorporated within the streamlined approach.
Food addiction spectrum: a theoretical model from normality to eating and overeating disorders.
Piccinni, Armando; Marazziti, Donatella; Vanelli, Federica; Franceschini, Caterina; Baroni, Stefano; Costanzo, Davide; Cremone, Ivan Mirko; Veltri, Antonello; Dell'Osso, Liliana
2015-01-01
The authors comment on the recently proposed food addiction spectrum that represents a theoretical model to understand the continuum between several conditions ranging from normality to pathological states, including eating disorders and obesity, as well as why some individuals show a peculiar attachment to food that can become an addiction. Further, they review the possible neurobiological underpinnings of these conditions that include dopaminergic neurotransmission and circuits that have long been implicated in drug addiction. The aim of this article is also that at stimulating a debate regarding the possible model of a food (or eating) addiction spectrum that may be helpful towards the search of novel therapeutic approaches to different pathological states related to disturbed feeding or overeating.
The structure and dynamics of cities urban data analysis and theoretical modeling
Barthelemy, Marc
2016-01-01
With over half of the world's population now living in urban areas, the ability to model and understand the structure and dynamics of cities is becoming increasingly valuable. Combining new data with tools and concepts from statistical physics and urban economics, this book presents a modern and interdisciplinary perspective on cities and urban systems. Both empirical observations and theoretical approaches are critically reviewed, with particular emphasis placed on derivations of classical models and results, along with analysis of their limits and validity. Key aspects of cities are thoroughly analyzed, including mobility patterns, the impact of multimodality, the coupling between different transportation modes, the evolution of infrastructure networks, spatial and social organisation, and interactions between cities. Drawing upon knowledge and methods from areas of mathematics, physics, economics and geography, the resulting quantitative description of cities will be of interest to all those studying and r...
Detailed Theoretical Model for Adjustable Gain-Clamped Semiconductor Optical Amplifier
Lin Liu
2012-01-01
Full Text Available The adjustable gain-clamped semiconductor optical amplifier (AGC-SOA uses two SOAs in a ring-cavity topology: one to amplify the signal and the other to control the gain. The device was designed to maximize the output saturated power while adjusting gain to regulate power differences between packets without loss of linearity. This type of subsystem can be used for power equalisation and linear amplification in packet-based dynamic systems such as passive optical networks (PONs. A detailed theoretical model is presented in this paper to simulate the operation of the AGC-SOA, which gives a better understanding of the underlying gain clamping mechanics. Simulations and comparisons with steady-state and dynamic gain modulation experimental performance are given which validate the model.
U.S. hegemony and the policy of regional modeling: Theoretical framework
Davut Ateş
2009-02-01
Full Text Available In this essay, ‘‘regional modelling’’ that has been increasingly applied as an hegemonic policy almost for the last twenty years is examined with a view to clarify the locus of that policy in international relation theory. Some states at regional level are examplified through modelling based on free market principles, democratic norms and civil society; so that it is targeted that form of statehood of all states at global scale is singularized. Taking into account the reality that current international system is unipolar in which U.S. is the hegemonic power; to connect the initiation of transforming states in developing and underdeveloped regions in line with the models proposed, with main theoretical approaches in international relations might contribute to a certain extent to understanding current world politics.
Forward model theoretical basis for a superconducting imaging surface magnetoencephalography system
Maharajh, K [University of New Mexico, Albuquerque, NM (United States); Volegov, P L [Los Alamos National Laboratory, Los Alamos, NM (United States); Kraus, R H [Los Alamos National Laboratory, Los Alamos, NM (United States)
2004-02-21
A novel magnetoencephalography (MEG) system was designed at Los Alamos National Laboratory (LANL) that incorporates a helmet-shaped superconductor in order to increase the signal to noise ratio. The magnetic field perturbations caused by the superconducting surface must be included in the forward physics for accurate source localization. In this paper, the theoretical basis for the forward model that calculates the field of any magnetic source in the presence of an arbitrarily shaped superconducting surface is presented. Appropriate magnetic field integral equations are derived that provide a description of the physics of the forward model. These equations are derived starting from Maxwell's equations in the presence of inhomogeneous media, with the appropriate boundary conditions for a superconductor. A discretized version of this equation is then compared with known analytic solutions for simple superconducting surface geometries.
Helal, Yaser H.; Neese, Christopher F.; De Lucia, Frank C.; Ewing, Paul R.; Agarwal, Ankur; Craver, Barry; Stout, Phillip J.; Armacost, Michael D.
2015-06-01
Plasmas used in the semiconductor manufacturing industry are of a similar nature to the environments often created for submillimeter spectroscopic study of astrophysical species. At the low operating pressures of these plasmas, submillimeter absorption spectroscopy is a method capable of measuring the abundances and temperatures of molecules, radicals, and ions without disturbing any of the properties of the plasma. These measurements provide details and insight into the interactions and reactions occurring within the plasma and their implications for semiconductor manufacturing processes. A continuous wave, 500 to 750 GHz, absorption spectrometer was designed and used to make measurements of species in semiconductor processing plasmas. Comparisons with expectations from theoretical plasma models provide a basis for validating and improving these models, which is a complex and difficult science itself. Furthermore, these comparisons are an evaluation for the use of submillimeter spectroscopy as a diagnostic tool in manufacturing processes.
Deserno, Markus; Paulsen, Harald; Peter, Christine; Schmid, Friederike
2014-01-01
This chapter summarizes several approaches combining theory, simulation and experiment that aim for a better understanding of phenomena in lipid bilayers and membrane protein systems, covering topics such as lipid rafts, membrane mediated interactions, attraction between transmembrane proteins, and aggregation in biomembranes leading to large superstructures such as the light harvesting complex of green plants. After a general overview of theoretical considerations and continuum theory of lipid membranes we introduce different options for simulations of biomembrane systems, addressing questions such as: What can be learned from generic models? When is it expedient to go beyond them? And what are the merits and challenges for systematic coarse graining and quasi-atomistic coarse grained models that ensure a certain chemical specificity?
Theoretical size distribution of fossil taxa: analysis of a null model
Hughes Barry D
2007-03-01
Full Text Available Abstract Background This article deals with the theoretical size distribution (of number of sub-taxa of a fossil taxon arising from a simple null model of macroevolution. Model New species arise through speciations occurring independently and at random at a fixed probability rate, while extinctions either occur independently and at random (background extinctions or cataclysmically. In addition new genera are assumed to arise through speciations of a very radical nature, again assumed to occur independently and at random at a fixed probability rate. Conclusion The size distributions of the pioneering genus (following a cataclysm and of derived genera are determined. Also the distribution of the number of genera is considered along with a comparison of the probability of a monospecific genus with that of a monogeneric family.
A Unified Theoretical Framework for Mapping Models for the Multi-State Hamiltonian
Liu, Jian
2016-01-01
We propose a new unified theoretical framework to construct equivalent representations of the multi-state Hamiltonian operator and present several approaches for the mapping onto the Cartesian phase space. After mapping an F-dimensional Hamiltonian onto an F+1- dimensional space, creation and annihilation operators are defined such that the F+1 dimensional space is complete for any combined excitations. Commutation and anti-commutation relations are then naturally derived, which show that the underlying degrees of freedom are neither bosons nor fermions. This sets the scene for developing equivalent expressions of the Hamiltonian operator in quantum mechanics and their classical/semiclassical counterparts. Six mapping models are presented as examples. The framework also offers a novel way to derive such as the well-known Meyer-Miller model.
Main ideas to consider in the elaboration of a new theoretical model of the clinical method.
Luis Alberto Corona Martínez
2006-12-01
Full Text Available In this article are exposed the main ideas that has been used for the elaboration of a new theoretical model of the clinical process, with the aim of being used as a teaching content in the Medicine career. Such ideas are: the necessity of a total correspondence between the process method and its objective, the conception of the medical attention process as a decision-taking process, the necessity of highlighting the human dimension of the medical practice, and the convenience of counting with a synthetic representation of the clinical method that facilitates its learning and comprehension. These elements will make possible that the clinical method model facilitates the learning and posterior performance of a more effective and efficient medical attention process, with the following betterment of the medical services’ quality and of the patients’ satisfaction.
Toward a unifying model of identification with groups: integrating theoretical perspectives.
Roccas, Sonia; Sagiv, Lilach; Schwartz, Shalom; Halevy, Nir; Eidelson, Roy
2008-08-01
Building on the contributions of diverse theoretical approaches, the authors present a multidimensional model of group identification. Integrating conceptions from the social identity perspective with those from research on individualism-collectivism, nationalism- patriotism, and identification with organizations, we propose four conceptually distinct modes of identification: importance (how much I view the group as part of who I am), commitment (how much I want to benefit the group), superiority (how much I view my group as superior to other groups), and deference (how much I honor, revere, and submit to the group's norms, symbols, and leaders). We present an instrument for assessing the four modes of identification and review initial empirical findings that validate the proposed model and show its utility in understanding antecedents and consequences of identification.
Theoretical model atmosphere spectra used for the calibration of infrared instruments
Decin, L
2007-01-01
One of the key ingredients in establishing the relation between input signal and output flux from a spectrometer is accurate determination of the spectrophotometric calibration. In the case of spectrometers onboard satellites, the accuracy of this part of the calibration pedigree is ultimately linked to the accuracy of the set of reference SEDs that the spectrophotometric calibration is built on. In this paper, we deal with the spectrophotometric calibration of infrared (IR) spectrometers onboard satellites in the 2 to 200 micron range. We aim at comparing the different reference SEDs used for the IR spectrophotometric calibration. The emphasis is on the reference SEDs of stellar standards with spectral type later than A0, with special focus on the theoretical model atmosphere spectra. Using the MARCS model atmosphere code, spectral reference SEDs were constructed for a set of IR stellar standards (A dwarfs, solar analogs, G9-M0 giants). A detailed error analysis was performed to estimate proper uncertainties...
REN ZhiPeng; WAN WeiXing; WEI Yong; LIU LiBo; YU Tao
2008-01-01
The geomagnetic fields, which play important roles in the ionospheric dynamo, can greatly affect the global distribution of ionospheric electric fields, currents and other ionospheric electrodynamics phenomena. In the study of ionospheric electrodynamics phenomena, such as the longitudinal variations of ionospheric electric fields, the non-dipolar component of the geomagnetic fields must be taken into account. In this paper, we deduce a theoretical electric field model for ionospheric dynamo at midand low-latitude which adopt a modified magnetic apex coordinates system. In the new electric field model, the geomagnetic fields can be calculated from either the IGRF model or the dipole field model,and the neutral winds and conductivities are calculated based on empirical models. Then the dynamo equation for the electric potential is finally solved in terms of the line-by-line iteration method, and the ionospheric electric fields and currents are derived from the calculated potential. Our model can reproduce the main features of the ionospheric electrodynamics processes, so it will be a useful tool for the investigation of the upper atmosphere and ionosphere.
Czoli Christine
2011-10-01
Full Text Available Abstract Physician-researchers are bound by professional obligations stemming from both the role of the physician and the role of the researcher. Currently, the dominant models for understanding the relationship between physician-researchers' clinical duties and research duties fit into three categories: the similarity position, the difference position and the middle ground. The law may be said to offer a fourth "model" that is independent from these three categories. These models frame the expectations placed upon physician-researchers by colleagues, regulators, patients and research participants. This paper examines the extent to which the data from semi-structured interviews with 30 physician-researchers at three major pediatric hospitals in Canada reflect these traditional models. It seeks to determine the extent to which existing models align with the described lived experience of the pediatric physician-researchers interviewed. Ultimately, we find that although some physician-researchers make references to something like the weak version of the similarity position, the pediatric-researchers interviewed in this study did not describe their dual roles in a way that tightly mirrors any of the existing theoretical frameworks. We thus conclude that either physician-researchers are in need of better training regarding the nature of the accountability relationships that flow from their dual roles or that models setting out these roles and relationships must be altered to better reflect what we can reasonably expect of physician-researchers in a real-world environment.
M. Shafieinia; A.R. Heidarnia; A. Kazemnejad; R. Rajabi
2015-01-01
... .The purpose of this study was to investigate the effective psychometric factors on physical activity of female employees, according to the Trans-theoretical Model and theory of planned behavior. Materials & Methods...
Tobias, B. J.; Boivin, R. L.; Boom, J. E.; Classen, I.G.J.; Domier, C.W.; Donne, A. J. H.; Heidbrink, W. W.; N C Luhmann Jr.,; Munsat, T.; Muscatello, C. M.; Nazikian, R.; Park, H. K.; Spong, D. A.; Turnbull, A. D.; VanZeeland, M. A.; Yun, G. S.
2011-01-01
Two-dimensional (2D) imaging of electron temperature perturbations provides a powerful constraint for validating theoretical models describing magnetohydrodynamic plasma behavior. In observation of Alfven wave induced temperature fluctuations, electron cyclotron emission imaging provides unambiguous
MIP models for connected facility location: A theoretical and computational study☆
Gollowitzer, Stefan; Ljubić, Ivana
2011-01-01
This article comprises the first theoretical and computational study on mixed integer programming (MIP) models for the connected facility location problem (ConFL). ConFL combines facility location and Steiner trees: given a set of customers, a set of potential facility locations and some inter-connection nodes, ConFL searches for the minimum-cost way of assigning each customer to exactly one open facility, and connecting the open facilities via a Steiner tree. The costs needed for building the Steiner tree, facility opening costs and the assignment costs need to be minimized. We model ConFL using seven compact and three mixed integer programming formulations of exponential size. We also show how to transform ConFL into the Steiner arborescence problem. A full hierarchy between the models is provided. For two exponential size models we develop a branch-and-cut algorithm. An extensive computational study is based on two benchmark sets of randomly generated instances with up to 1300 nodes and 115,000 edges. We empirically compare the presented models with respect to the quality of obtained bounds and the corresponding running time. We report optimal values for all but 16 instances for which the obtained gaps are below 0.6%. PMID:25009366
MIP models for connected facility location: A theoretical and computational study.
Gollowitzer, Stefan; Ljubić, Ivana
2011-02-01
This article comprises the first theoretical and computational study on mixed integer programming (MIP) models for the connected facility location problem (ConFL). ConFL combines facility location and Steiner trees: given a set of customers, a set of potential facility locations and some inter-connection nodes, ConFL searches for the minimum-cost way of assigning each customer to exactly one open facility, and connecting the open facilities via a Steiner tree. The costs needed for building the Steiner tree, facility opening costs and the assignment costs need to be minimized. We model ConFL using seven compact and three mixed integer programming formulations of exponential size. We also show how to transform ConFL into the Steiner arborescence problem. A full hierarchy between the models is provided. For two exponential size models we develop a branch-and-cut algorithm. An extensive computational study is based on two benchmark sets of randomly generated instances with up to 1300 nodes and 115,000 edges. We empirically compare the presented models with respect to the quality of obtained bounds and the corresponding running time. We report optimal values for all but 16 instances for which the obtained gaps are below 0.6%.
Theoretical Basis and Application of an Analogue-Dynamical Model in the Lorenz System
REN Hongli; CHOU Jifan; HUANG Jianping; ZHANG Peiqun
2009-01-01
The theoretical basis and application of an analogue-dynamical model (ADM) in the Lorenz system is studied. The ADM can effectively combine statistical and dynamical methods in which the small disturbance of the current initial value superimposed on the historical analogue reference state can be regarded as a prediction objective. Primary analyses show that under the condition of appending disturbances in model parameters, the model errors of ADM are much smaller than those of the pure dynamical model (PDM).The characteristics of predictability on the ADM in the Lorenz system are analyzed in phase space by conducting case studies and global experiments. The results show that the ADM can quite effectively reduce prediction errors and prolong the valid time of the prediction in most situations in contrast to the PDM, but when model errors are considerably small, the latter will be superior to the former. To overcome such a problem, the multi-reference-state updating can be applied to introduce the information of multi-analogue and update analogue and can exhibit exciting performance in the ADM.
Theoretical vibro-acoustic modeling of acoustic noise transmission through aircraft windows
Aloufi, Badr; Behdinan, Kamran; Zu, Jean
2016-06-01
In this paper, a fully vibro-acoustic model for sound transmission across a multi-pane aircraft window is developed. The proposed model is efficiently applied for a set of window models to perform extensive theoretical parametric studies. The studied window configurations generally simulate the passenger window designs of modern aircraft classes which have an exterior multi-Plexiglas pane, an interior single acrylic glass pane and a dimmable glass ("smart" glass), all separated by thin air cavities. The sound transmission loss (STL) characteristics of three different models, triple-, quadruple- and quintuple-paned windows identical in size and surface density, are analyzed for improving the acoustic insulation performances. Typical results describing the influence of several system parameters, such as the thicknesses, number and spacing of the window panes, on the transmission loss are then investigated. In addition, a comparison study is carried out to evaluate the acoustic reduction capability of each window model. The STL results show that the higher frequencies sound transmission loss performance can be improved by increasing the number of window panels, however, the low frequency performance is decreased, particularly at the mass-spring resonances.
A theoretical-electron-density databank using a model of real and virtual spherical atoms.
Nassour, Ayoub; Domagala, Slawomir; Guillot, Benoit; Leduc, Theo; Lecomte, Claude; Jelsch, Christian
2017-08-01
A database describing the electron density of common chemical groups using combinations of real and virtual spherical atoms is proposed, as an alternative to the multipolar atom modelling of the molecular charge density. Theoretical structure factors were computed from periodic density functional theory calculations on 38 crystal structures of small molecules and the charge density was subsequently refined using a density model based on real spherical atoms and additional dummy charges on the covalent bonds and on electron lone-pair sites. The electron-density parameters of real and dummy atoms present in a similar chemical environment were averaged on all the molecules studied to build a database of transferable spherical atoms. Compared with the now-popular databases of transferable multipolar parameters, the spherical charge modelling needs fewer parameters to describe the molecular electron density and can be more easily incorporated in molecular modelling software for the computation of electrostatic properties. The construction method of the database is described. In order to analyse to what extent this modelling method can be used to derive meaningful molecular properties, it has been applied to the urea molecule and to biotin/streptavidin, a protein/ligand complex.
Defense of Cyber Infrastructures Against Cyber-Physical Attacks Using Game-Theoretic Models.
Rao, Nageswara S V; Poole, Stephen W; Ma, Chris Y T; He, Fei; Zhuang, Jun; Yau, David K Y
2016-04-01
The operation of cyber infrastructures relies on both cyber and physical components, which are subject to incidental and intentional degradations of different kinds. Within the context of network and computing infrastructures, we study the strategic interactions between an attacker and a defender using game-theoretic models that take into account both cyber and physical components. The attacker and defender optimize their individual utilities, expressed as sums of cost and system terms. First, we consider a Boolean attack-defense model, wherein the cyber and physical subinfrastructures may be attacked and reinforced as individual units. Second, we consider a component attack-defense model wherein their components may be attacked and defended, and the infrastructure requires minimum numbers of both to function. We show that the Nash equilibrium under uniform costs in both cases is computable in polynomial time, and it provides high-level deterministic conditions for the infrastructure survival. When probabilities of successful attack and defense, and of incidental failures, are incorporated into the models, the results favor the attacker but otherwise remain qualitatively similar. This approach has been motivated and validated by our experiences with UltraScience Net infrastructure, which was built to support high-performance network experiments. The analytical results, however, are more general, and we apply them to simplified models of cloud and high-performance computing infrastructures.
Bornaetxea, Txomin; Antigüedad, Iñaki; Ormaetxea, Orbange
2016-04-01
In the Oria river basin (885 km2) shallow landslides are very frequent and they produce several roadblocks and damage in the infrastructure and properties, causing big economic loss every year. Considering that the zonification of the territory in different landslide susceptibility levels provides a useful tool for the territorial planning and natural risk management, this study has the objective of identifying the most prone landslide places applying an objective and reproducible methodology. To do so, a quantitative multivariate methodology, the logistic regression, has been used. Fieldwork landslide points and randomly selected stable points have been used along with Lithology, Land Use, Distance to the transport infrastructure, Altitude, Senoidal Slope and Normalized Difference Vegetation Index (NDVI) independent variables to carry out a landslide susceptibility map. The model has been validated by the prediction and success rate curves and their corresponding area under the curve (AUC). In addition, the result has been compared to those from two landslide susceptibility models, covering the study area previously applied in different scales, such as ELSUS1000 version 1 (2013) and Landslide Susceptibility Map of Gipuzkoa (2007). Validation results show an excellent prediction capacity of the proposed model (AUC 0,962), and comparisons highlight big differences with previous studies.
Jones-Farrand, D. Todd; Fearer, Todd M.; Thogmartin, Wayne E.; Thompson, Frank R.; Nelson, Mark D.; Tirpak, John M.
2011-01-01
Selection of a modeling approach is an important step in the conservation planning process, but little guidance is available. We compared two statistical and three theoretical habitat modeling approaches representing those currently being used for avian conservation planning at landscape and regional scales: hierarchical spatial count (HSC), classification and regression tree (CRT), habitat suitability index (HSI), forest structure database (FS), and habitat association database (HA). We focused our comparison on models for five priority forest-breeding species in the Central Hardwoods Bird Conservation Region: Acadian Flycatcher, Cerulean Warbler, Prairie Warbler, Red-headed Woodpecker, and Worm-eating Warbler. Lacking complete knowledge on the distribution and abundance of each species with which we could illuminate differences between approaches and provide strong grounds for recommending one approach over another, we used two approaches to compare models: rank correlations among model outputs and comparison of spatial correspondence. In general, rank correlations were significantly positive among models for each species, indicating general agreement among the models. Worm-eating Warblers had the highest pairwise correlations, all of which were significant (P , 0.05). Red-headed Woodpeckers had the lowest agreement among models, suggesting greater uncertainty in the relative conservation value of areas within the region. We assessed model uncertainty by mapping the spatial congruence in priorities (i.e., top ranks) resulting from each model for each species and calculating the coefficient of variation across model ranks for each location. This allowed identification of areas more likely to be good targets of conservation effort for a species, those areas that were least likely, and those in between where uncertainty is higher and thus conservation action incorporates more risk. Based on our results, models developed independently for the same purpose
Gutierrez Pablo
2001-01-01
Full Text Available Cry11Bb is an insecticidal crystal protein produced by Bacillus thuringiensis subsp. medellin during its stationary phase; this ¶-endotoxin is active against dipteran insects and has great potential for mosquito borne disease control. Here, we report the first theoretical model of the tridimensional structure of a Cry11 toxin. The tridimensional structure of the Cry11Bb toxin was obtained by homology modelling on the structures of the Cry1Aa and Cry3Aa toxins. In this work we give a brief description of our model and hypothesize the residues of the Cry11Bb toxin that could be important in receptor recognition and pore formation. This model will serve as a starting point for the design of mutagenesis experiments aimed to the improvement of toxicity, and to provide a new tool for the elucidation of the mechanism of action of these mosquitocidal proteins.
Multinucleon short-range correlation model for nuclear spectral functions: Theoretical framework
Artiles, Oswaldo; Sargsian, Misak M.
2016-12-01
We develop a theoretical approach for nuclear spectral functions at high missing momenta and removal energies based on the multinucleon short-range correlation (SRC) model. The approach is based on the effective Feynman diagrammatic method which allows us to account for the relativistic effects important in the SRC domain. In addition to two-nucleon (2N) SRC with center of mass motion we also derive the contribution of three-nucleon SRCs to the nuclear spectral functions. The latter is modeled based on the assumption that 3N SRCs are a product of two sequential short-range nucleon-nucleon (NN) interactions. This approach allows us to express the 3N SRC part of the nuclear spectral function as a convolution of two NN SRCs. Thus the knowledge of 2N SRCs allows us to model both two- and three-nucleon SRC contributions to the spectral function. The derivations of the spectral functions are based on two theoretical frameworks for evaluating covariant Feynman diagrams: In the first, referred to as virtual nucleon approximation, we reduce Feynman diagrams to the time ordered noncovariant diagrams by evaluating nucleon spectators in the SRC at their positive energy poles, neglecting explicitly the contribution from vacuum diagrams. In the second approach, referred to as light-front approximation, we formulate the boost invariant nuclear spectral function in the light-front reference frame in which case the vacuum diagrams are generally suppressed and the bound nucleon is described by its light-front variables such as momentum fraction, transverse momentum, and invariant mass.
New theoretical model of New Service Development process in Iranian Governmental Banks
Nasrollah Shabankareh
2013-08-01
Full Text Available The intensive competition in grasping banking customers, as well as the rapid growth in customers' needs for high quality, proper services have given rise to new innovative methods for optimization of processes, service development and value creation in Iranian Governmental bank systems. Today organizing a new service development is an important topic for decision-delivery in service banks. New Service Development (NSD process providing the lower cost and higher benefit methods for creation of competitive advantage in Governmental banking systems. In this paper the new theoretical model of New Service Development process in Iranian Governmental Banks has been introduced. The qualitative data was collected through interviews. The methodology is adapted from in-depth interviews with academic experts and managers of Governmental banking systems until theoretical saturation state achieved. The gathered data was analyzed using axial and open coding methods. The results shows that the NSD process Iranian Governmental banking systems is includes of four main stages and 35 secondary factors consist of analysis& new concept development, design, pilot and launch, development. Eventually, the results of this paper can be used for the new services development in Governmental banking system in a competitive environment at the other countries.
Ferguson, Eamonn
2013-01-01
This paper sets out the case that personality traits are central to health psychology. To achieve this, three aims need to be addressed. First, it is necessary to show that personality influences a broad range of health outcomes and mechanisms. Second, the simple descriptive account of Aim 1 is not sufficient, and a theoretical specification needs to be developed to explain the personality-health link and allow for future hypothesis generation. Third, once Aims 1 and 2 are met, it is necessary to demonstrate the clinical utility of personality. In this review I make the case that all three Aims are met. I develop a theoretical framework to understand the links between personality and health drawing on current theorising in the biology, evolution, and neuroscience of personality. I identify traits (i.e., alexithymia, Type D, hypochondriasis, and empathy) that are of particular concern to health psychology and set these within evolutionary cost-benefit analysis. The literature is reviewed within a three-level hierarchical model (individual, group, and organisational) and it is argued that health psychology needs to move from its traditional focus on the individual level to engage group and organisational levels. PMID:23772230
Ferguson, Eamonn
2013-05-01
This paper sets out the case that personality traits are central to health psychology. To achieve this, three aims need to be addressed. First, it is necessary to show that personality influences a broad range of health outcomes and mechanisms. Second, the simple descriptive account of Aim 1 is not sufficient, and a theoretical specification needs to be developed to explain the personality-health link and allow for future hypothesis generation. Third, once Aims 1 and 2 are met, it is necessary to demonstrate the clinical utility of personality. In this review I make the case that all three Aims are met. I develop a theoretical framework to understand the links between personality and health drawing on current theorising in the biology, evolution, and neuroscience of personality. I identify traits (i.e., alexithymia, Type D, hypochondriasis, and empathy) that are of particular concern to health psychology and set these within evolutionary cost-benefit analysis. The literature is reviewed within a three-level hierarchical model (individual, group, and organisational) and it is argued that health psychology needs to move from its traditional focus on the individual level to engage group and organisational levels.
Behar, Evelyn; DiMarco, Ilyse Dobrow; Hekler, Eric B; Mohlman, Jan; Staples, Alison M
2009-12-01
Theoretical conceptualizations of generalized anxiety disorder (GAD) continue to undergo scrutiny and refinement. The current paper critiques five contemporary models of GAD: the Avoidance Model of Worry and GAD [Borkovec, T. D. (1994). The nature, functions, and origins of worry. In: G. Davey & F. Tallis (Eds.), Worrying: perspectives on theory assessment and treatment (pp. 5-33). Sussex, England: Wiley & Sons; Borkovec, T. D., Alcaine, O. M., & Behar, E. (2004). Avoidance theory of worry and generalized anxiety disorder. In: R. Heimberg, C. Turk, & D. Mennin (Eds.), Generalized anxiety disorder: advances in research and practice (pp. 77-108). New York, NY, US: Guilford Press]; the Intolerance of Uncertainty Model [Dugas, M. J., Letarte, H., Rheaume, J., Freeston, M. H., & Ladouceur, R. (1995). Worry and problem solving: evidence of a specific relationship. Cognitive Therapy and Research, 19, 109-120; Freeston, M. H., Rheaume, J., Letarte, H., Dugas, M. J., & Ladouceur, R. (1994). Why do people worry? Personality and Individual Differences, 17, 791-802]; the Metacognitive Model [Wells, A. (1995). Meta-cognition and worry: a cognitive model of generalized anxiety disorder. Behavioural and Cognitive Psychotherapy, 23, 301-320]; the Emotion Dysregulation Model [Mennin, D. S., Heimberg, R. G., Turk, C. L., & Fresco, D. M. (2002). Applying an emotion regulation framework to integrative approaches to generalized anxiety disorder. Clinical Psychology: Science and Practice, 9, 85-90]; and the Acceptance-based Model of GAD [Roemer, L., & Orsillo, S. M. (2002). Expanding our conceptualization of and treatment for generalized anxiety disorder: integrating mindfulness/acceptance-based approaches with existing cognitive behavioral models. Clinical Psychology: Science and Practice, 9, 54-68]. Evidence in support of each model is critically reviewed, and each model's corresponding evidence-based therapeutic interventions are discussed. Generally speaking, the models share an
Taormina, R.; Galelli, S.; Karakaya, G.; Ahipasaoglu, S. D.
2016-11-01
This work investigates the uncertainty associated to the presence of multiple subsets of predictors yielding data-driven models with the same, or similar, predictive accuracy. To handle this uncertainty effectively, we introduce a novel input variable selection algorithm, called Wrapper for Quasi Equally Informative Subset Selection (W-QEISS), specifically conceived to identify all alternate subsets of predictors in a given dataset. The search process is based on a four-objective optimization problem that minimizes the number of selected predictors, maximizes the predictive accuracy of a data-driven model and optimizes two information theoretic metrics of relevance and redundancy, which guarantee that the selected subsets are highly informative and with little intra-subset similarity. The algorithm is first tested on two synthetic test problems and then demonstrated on a real-world streamflow prediction problem in the Yampa River catchment (US). Results show that complex hydro-meteorological datasets are characterized by a large number of alternate subsets of predictors, which provides useful insights on the underlying physical processes. Furthermore, the presence of multiple subsets of predictors-and associated models-helps find a better trade-off between different measures of predictive accuracy commonly adopted for hydrological modelling problems.
XU MingZhu; LIU XinHui; WANG Liang; WU Dan; SUN Tao; YANG ZhiFeng; CUI BaoShan
2009-01-01
Using theoretical molecular descriptors as well as partial least squares (PLS) regression,two quantitative structure-activity relationship (QSAR) models were developed for depuration rate constants (kd) of polychlorinated biphenyls (PCBs) in two species of mussels,Perna viridis and Dreissena polymorpha.Thecross-validated Q2cum (an indicator of fitting of goodness) values for the two models are 0.501 and 0.756,and the standard deviation (SO) is 0.084 and 0.076,respectively.The achievement of satisfactory Q2cumand low SD values indicates good predictive ability and precision of the two models.The significant descriptors governing Igkd include polarizability (a),molecular volume (/Mv),molecular weight (Mw),molecular surface area (S),and total energy (TE).The key descriptors in the models reflect that van der Waals interactions play a dominant role in the depuration of PCBs.The depuration of PCBs in the two mussel species may be mainly attributed to the biota-water phase partitioning processes.
A novel theoretical model for the temperature dependence of band gap energy in semiconductors
Geng, Peiji; Li, Weiguo; Zhang, Xianhe; Zhang, Xuyao; Deng, Yong; Kou, Haibo
2017-10-01
We report a novel theoretical model without any fitting parameters for the temperature dependence of band gap energy in semiconductors. This model relates the band gap energy at the elevated temperature to that at the arbitrary reference temperature. As examples, the band gap energies of Si, Ge, AlN, GaN, InP, InAs, ZnO, ZnS, ZnSe and GaAs at temperatures below 400 K are calculated and are in good agreement with the experimental results. Meanwhile, the band gap energies at high temperatures (T > 400 K) are predicted, which are greater than the experimental results, and the reasonable analysis is carried out as well. Under low temperatures, the effect of lattice expansion on the band gap energy is very small, but it has much influence on the band gap energy at high temperatures. Therefore, it is necessary to consider the effect of lattice expansion at high temperatures, and the method considering the effect of lattice expansion has also been given. The model has distinct advantages compared with the widely quoted Varshni’s semi-empirical equation from the aspect of modeling, physical meaning and application. The study provides a convenient method to determine the band gap energy under different temperatures.
无
2009-01-01
Using theoretical molecular descriptors as well as partial least squares(PLS) regression,two quantitative structure-activity relationship(QSAR) models were developed for depuration rate constants(kd) of polychlorinated biphenyls(PCBs) in two species of mussels,Perna viridis and Dreissena polymorpha.The cross-validated Q2cum(an indicator of fitting of goodness) values for the two models are 0.501 and 0.756,and the standard deviation(SD) is 0.084 and 0.076,respectively.The achievement of satisfactory Q2cum and low SD values indicates good predictive ability and precision of the two models.The significant descriptors governing lgkd include polarizability(α),molecular volume(MV),molecular weight(Mw),molecular surface area(S),and total energy(TE).The key descriptors in the models reflect that van der Waals interactions play a dominant role in the depuration of PCBs.The depuration of PCBs in the two mussel species may be mainly attributed to the biota-water phase partitioning processes.
Theoretical aspects and practical implications of the heuristic drift SOL model
Goldston, R.J., E-mail: goldston@pppl.gov
2015-08-15
The heuristic drift (HD) model for the tokamak power scrape-off layer width provides remarkable agreement in both absolute magnitude and scalings with the measured width of the exponential component of the heat flux at divertors targets, in low gas-puff H-Mode tokamaks. This motivates further exploration of its theoretical aspects and practical implications. The HD model requires a small non-ambipolar electron particle diffusivity ∼10{sup −2} m{sup 2}/s. It also implies large parallel heat flux in ITER and suggests that more radical approaches will be needed to handle the ∼20 GW/m{sup 2} parallel heat flux expected in Demo. Remarkably, the HD model is also in good agreement with recent near-SOL heat flux profiles measured in a number of limiter L-Mode experiments, implying ubiquity of the underlying mechanism. Finally, the HD model suggests that the H-Mode and more generally Greenwald density limit may be caused by MHD instability in the SOL, rather than originating in the core plasma or pedestal. If the SOL width in stellarators is set by magnetic topology rather than by drifts, this would be consistent with the absence of the Greenwald density limit in stellarators.
Chen, Yun; Yang, Hui
2016-12-01
In the era of big data, there are increasing interests on clustering variables for the minimization of data redundancy and the maximization of variable relevancy. Existing clustering methods, however, depend on nontrivial assumptions about the data structure. Note that nonlinear interdependence among variables poses significant challenges on the traditional framework of predictive modeling. In the present work, we reformulate the problem of variable clustering from an information theoretic perspective that does not require the assumption of data structure for the identification of nonlinear interdependence among variables. Specifically, we propose the use of mutual information to characterize and measure nonlinear correlation structures among variables. Further, we develop Dirichlet process (DP) models to cluster variables based on the mutual-information measures among variables. Finally, orthonormalized variables in each cluster are integrated with group elastic-net model to improve the performance of predictive modeling. Both simulation and real-world case studies showed that the proposed methodology not only effectively reveals the nonlinear interdependence structures among variables but also outperforms traditional variable clustering algorithms such as hierarchical clustering.
How Do Trading Firms Upgrade Skills and Technology: A Theoretical Model
Mojca Lindic
2015-12-01
Full Text Available This paper studies the mechanisms of skill upgrading in trading firms by developing a theoretical model that relates the individual’s incentives for acquiring higher skills to the profit-maximizing behaviour of trading firms. The model shows that only the high ability individuals have incentives for acquiring higher skills, as long as they are compensated with higher wages after entering employment. Furthermore, high-productive firms have incentives for investing in higher technology, to employ high-skilled labour, and to engage in international trade. The decisions for technology dress-up and skill upgrading coincide with firm’s decisions to start importing and exporting as the latter requires higher technology and high-skilled labour. Contributions of the paper are twofold: gaining new insights by combining fragments of models on individual’s and firm’s behaviours, and broadening the content of the Melitz (2003 model by introducing importers and controlling for skilled and unskilled labour.
Chen, Yun; Yang, Hui
2016-12-14
In the era of big data, there are increasing interests on clustering variables for the minimization of data redundancy and the maximization of variable relevancy. Existing clustering methods, however, depend on nontrivial assumptions about the data structure. Note that nonlinear interdependence among variables poses significant challenges on the traditional framework of predictive modeling. In the present work, we reformulate the problem of variable clustering from an information theoretic perspective that does not require the assumption of data structure for the identification of nonlinear interdependence among variables. Specifically, we propose the use of mutual information to characterize and measure nonlinear correlation structures among variables. Further, we develop Dirichlet process (DP) models to cluster variables based on the mutual-information measures among variables. Finally, orthonormalized variables in each cluster are integrated with group elastic-net model to improve the performance of predictive modeling. Both simulation and real-world case studies showed that the proposed methodology not only effectively reveals the nonlinear interdependence structures among variables but also outperforms traditional variable clustering algorithms such as hierarchical clustering.
Doinikov, Alexander A., E-mail: doinikov@bsu.by; Bouakaz, Ayache [Inserm U930, Université François Rabelais, Tours 37044 (France); Sheeran, Paul S.; Dayton, Paul A. [Joint Department of Biomedical Engineering, The University of North Carolina and North Carolina State University, Chapel Hill, North Carolina 27599 (United States)
2014-10-15
Purpose: Perfluorocarbon (PFC) microdroplets, called phase-change contrast agents (PCCAs), are a promising tool in ultrasound imaging and therapy. Interest in PCCAs is motivated by the fact that they can be triggered to transition from the liquid state to the gas state by an externally applied acoustic pulse. This property opens up new approaches to applications in ultrasound medicine. Insight into the physics of vaporization of PFC droplets is vital for effective use of PCCAs and for anticipating bioeffects. PCCAs composed of volatile PFCs (with low boiling point) exhibit complex dynamic behavior: after vaporization by a short acoustic pulse, a PFC droplet turns into a vapor bubble which undergoes overexpansion and damped radial oscillation until settling to a final diameter. This behavior has not been well described theoretically so far. The purpose of our study is to develop an improved theoretical model that describes the vaporization dynamics of volatile PFC droplets and to validate this model by comparison with in vitro experimental data. Methods: The derivation of the model is based on applying the mathematical methods of fluid dynamics and thermodynamics to the process of the acoustic vaporization of PFC droplets. The used approach corrects shortcomings of the existing models. The validation of the model is carried out by comparing simulated results with in vitro experimental data acquired by ultrahigh speed video microscopy for octafluoropropane (OFP) and decafluorobutane (DFB) microdroplets of different sizes. Results: The developed theory allows one to simulate the growth of a vapor bubble inside a PFC droplet until the liquid PFC is completely converted into vapor, and the subsequent overexpansion and damped oscillations of the vapor bubble, including the influence of an externally applied acoustic pulse. To evaluate quantitatively the difference between simulated and experimental results, the L2-norm errors were calculated for all cases where the
Doinikov, Alexander A; Sheeran, Paul S; Bouakaz, Ayache; Dayton, Paul A
2014-10-01
Perfluorocarbon (PFC) microdroplets, called phase-change contrast agents (PCCAs), are a promising tool in ultrasound imaging and therapy. Interest in PCCAs is motivated by the fact that they can be triggered to transition from the liquid state to the gas state by an externally applied acoustic pulse. This property opens up new approaches to applications in ultrasound medicine. Insight into the physics of vaporization of PFC droplets is vital for effective use of PCCAs and for anticipating bioeffects. PCCAs composed of volatile PFCs (with low boiling point) exhibit complex dynamic behavior: after vaporization by a short acoustic pulse, a PFC droplet turns into a vapor bubble which undergoes overexpansion and damped radial oscillation until settling to a final diameter. This behavior has not been well described theoretically so far. The purpose of our study is to develop an improved theoretical model that describes the vaporization dynamics of volatile PFC droplets and to validate this model by comparison with in vitro experimental data. The derivation of the model is based on applying the mathematical methods of fluid dynamics and thermodynamics to the process of the acoustic vaporization of PFC droplets. The used approach corrects shortcomings of the existing models. The validation of the model is carried out by comparing simulated results with in vitro experimental data acquired by ultrahigh speed video microscopy for octafluoropropane (OFP) and decafluorobutane (DFB) microdroplets of different sizes. The developed theory allows one to simulate the growth of a vapor bubble inside a PFC droplet until the liquid PFC is completely converted into vapor, and the subsequent overexpansion and damped oscillations of the vapor bubble, including the influence of an externally applied acoustic pulse. To evaluate quantitatively the difference between simulated and experimental results, the L2-norm errors were calculated for all cases where the simulated and experimental
Simple graph-theoretical model for flavonoid binding to P-glycoprotein.
Miličević, Ante; Raos, Nenad
2016-03-01
Three sets of flavonoid derivatives (N=32, 40, and 74) and logarithms of their dissociation constants (log Kd) that describe flavonoid affinity toward P-glycoprotein were modelled using six connectivity indices. The best results were obtained with the zero-order valence molecular connectivity index (0χv) for all three sets. Standard errors of the calibration models were around 0.3, and of the constants from the test sets even a little lower, 0.22 and 0.24. Despite using only one descriptor, our model proved better in internal (cross-validation) and especially in external (test set) statistics than much more demanding methods used in previous 3D QSAR modelling.
Petrov, Blagovest; Gräfener, Götz
2016-01-01
Luminous Blue Variables have been suggested to be the direct progenitors of supernova types IIb and IIn, with enhanced mass loss prior to explosion. However, the mechanism of this mass loss is not yet known. Here, we investigate the qualitative behaviour of theoretical stellar wind mass-loss as a function of Teff across two bi-stability jumps in blue supergiant regime and also in proximity to the Eddington limit, relevant for LBVs. To investigate the physical ingredients that play a role in the radiative acceleration we calculate blue supergiant wind models with the CMFGEN non-LTE model atmosphere code over an effective temperature range between 30000 and 8800 K. Although our aim is not to provide new mass-loss rates for BA supergiants, we study and confirm the existence of two bi-stability jumps in mass-loss rates predicted by Vink, de Koter, & Lamers (1999). However, they are found to occur at somewhat lower Teff (20000 and 9000 K, respectively) than found previously, which would imply that stars may ev...
Raj, Vivek [Indian Institute of Technology-Kanpur, Kanpur (India); Mistarihi, Qusai M.; Ryu, Ho Jin [KAIST, Daejeon (Korea, Republic of)
2015-10-15
The improvement of thermal properties of ZrO{sub 2} has been investigated in many ways to enhance the performance of inert matrix fuel (IMF). Inert matrix fuel is a useful concept to burn transuranic elements (TRU) without increasing extra plutonium. The addition of reinforcements with a high thermal conductivity has been proposed in the previous studies. Molybdenum and silicon carbide are good candidate materials for the reinforcement because of their high thermal conductivities and low neutron absorption cross sections. Recently, ZrO{sub 2}-based composites reinforced with Mo-wire mesh or carbon foam were fabricated by spark plasma sintering. When the effects of the structures of reinforcements were compared, interconnected structures provided more enhanced thermal conductivity than discrete structures. The effective thermal conductivity of composite materials with various reinforcement structures can be calculated by using the finite element analyses. The finite element analyses presented a good agreement with theoretical models in estimating the effects of the reinforcement on the thermal conductivities of discrete Mo reinforced ZrO{sub 2} nanocomposites. It is found that the effects of interconnected thermal reinforcements on the effective thermal conductivity can be estimated by using the percolation model.
Theoretical model estimation of guest diffusion in Metal-Organic Frameworks (MOFs)
Zheng, Bin
2015-08-11
Characterizing molecule diffusion in nanoporous matrices is critical to understanding the novel chemical and physical properties of metal-organic frameworks (MOFs). In this paper, we developed a theoretical model to fastly and accurately compute the diffusion rate of guest molecules in a zeolitic imidazolate framework-8 (ZIF-8). The ideal gas or equilibrium solution diffusion model was modified to contain the effect of periodical media via introducing the possibility of guests passing through the framework gate. The only input in our model is the energy barrier of guests passing through the MOF’s gate. Molecular dynamics (MD) methods were employed to gather the guest density profile, which then was used to deduce the energy barrier values. This produced reliable results that require a simulation time of 5 picoseconds, which is much shorter when using pure MD methods (in the billisecond scale) . Also, we used density functional theory (DFT) methods to obtain the energy profile of guests passing through gates, as this does not require specification of a force field for the MOF degrees of freedom. In the DFT calculation, we only considered one gate of MOFs each time; as this greatly reduced the computational cost. Based on the obtained energy barrier values we computed the diffusion rate of alkane and alcohol in ZIF-8 using our model, which was in good agreement with experimental test results and the calculation values from standard MD model. Our model shows the advantage of obtaining accurate diffusion rates for guests in MOFs for a lower computational cost and shorter calculation time. Thus, our analytic model calculation is especially attractive for high-throughput computational screening of the dynamic performance of guests in a framework.
Integrated Modeling in Earth and Space Sciences: An Information Theoretic Framework
Sharma, A. S.; Kalnay, E.
2011-12-01
Most natural phenomena exhibit multiscale behavior, which is an underlying reason for the challenges in modeling them. The recognition that the key problems, such as extreme events, natural hazards and climate change, require multi-disciplinary approaches to develop models that integrate many natural and anthropogenic phenomena, demand new approaches in the modeling of such systems. Information theory, which emphasizes the inherent features in observational data independent of modeling assumptions, can be used to develop a framework for multi-disciplinary models by integrating the data of the leading processes in multiple systems. An important measure of the inter-relationship among the different phenomena is the lead time among them. The widely used quantities such as the cross-correlation function represent the linear dependence among the variables and are limited in their ability to describe complex driven systems which are essentially nonlinear. The mutual information function, which represents the expectation of the average degree of dependence incorporating all orders of nonlinearity, provides the characteristic times inherent in the data and can be used as the first step to the development of integrated models. This function is used in two systems with widely separated time scales. The first case is the solar wind - magnetosphere interaction and the correlated data yield ~ 5 hr as the inherent time scale for the magnetospheric processes. The second case is a study of the inter-relationship between natural and anthropogenic phenomena and the mutual information functions were computed from the data of the global gross product, temperature and population. These functions show a time delay of ~15 yrs between the changes in global temperature and population as well as gross product, thus providing a measure of the interdependency among the variables underlying climate change. The results from studies of extreme events and an information theoretic modeling
Modeling and Analyzing Wavelet based Watermarking System using Game Theoretic Optimization Technique
Shweta
2011-03-01
Full Text Available This paper deals with establishing an economically viable and robust multilevel Game theoretic watermarking security system for the digital community; based on CPU time utilization with respect to channel capacity and system complexity. The coefficients of watermark are embedded into the host image at selected transformation level, which in turn extracted by inverse transformation at the decoder to develop the game matrix, which is iteratively searched for the optimized stable state for the system using permissible threshold. The rational thinking of maximizing the payoff of the watermarker (encoder with respect to the attacker (noise can be merged with the model deriving winning strategies to gain optimality. The data is rationally analyzed and tested to describe the behavior of the method for varying system parameter values and to gain performance optimization on different gray images with added Gaussian, salt and pepper, JPEG compression noises. Signal to noise ratio and correlation coefficients are used as criteria for testing the method.
Weiguo Li
2012-01-01
Full Text Available A thermodamage strength theoretical model taking into account the effect of residual stress was established and applied to each temperature phase based on the study of effects of various physical mechanisms on the fracture strength of ultrahigh-temperature ceramics. The effects of SiC particle size, crack size, and SiC particle volume fraction on strength corresponding to different temperatures were studied in detail. This study showed that when flaw size is not large, the bigger SiC particle size results in the greater effect of tensile residual stress in the matrix grains on strength reduction, and this prediction coincides with experimental results; and the residual stress and the combined effort of particle size and crack size play important roles in controlling material strength.
Construction and Evaluation of the Theoretical Model of Citrus Cooperative Organization
2010-01-01
Based on the general overview of cooperative economic organizations of citrus industry at home and abroad,theoretical model of the modernization,industrialization and marketization of Citrus Cooperative Organization is established.After selecting the indices,such as the scale of production,the scale of management,the rate of encouraged farmers,and the market competitiveness,quantitative evaluation index system for modernization,industrialization and marketization is established.Then,Citrus Cooperative Organization is divided into three stages,such as primary stage,intermediate stage and senior stage.After evaluating the modernization,industrialization and marketization of citrus industry in the United States,Spain and South Africa,it is pointed out that the Citrus Cooperative Organization in China at present is at the primary stage.Finally,policy direction of the development of Citrus Cooperative Organization in China is pointed out.
Theoretical Modeling and Simulation of Phase-Locked Loop (PLL) for Clock Data Recovery (CDR)
Ashari, Zainab
2012-01-01
Modern communication and computer systems require rapid (Gbps), efficient and large bandwidth data transfers. Agressive scaling of digital integrated systems allow buses and communication controller circuits to be integrated with the microprocessor on the same chip. The Peripheral Component Interconnect Express (PCIe) protocol handles all communcation between the central processing unit (CPU) and hardware devices. PCIe buses require efficient clock data recovery circuits (CDR) to recover clock signals embedded in data during transmission. This paper describes the theoretical modeling and simulation of a phase-locked loop (PLL) used in a CDR circuit. A simple PLL architecture for a 5 GHz CDR circuit is proposed and elaborated in this work. Simulations were carried out using a Hardware Description Language, Verilog- AMS. The effect of jitter on the proposed design is also simulated and evaluated in this work. It was found that the proposed design is robust against both input and VCO jitter.
Mechanical Relaxation of Metallic Glasses: An Overview of Experimental Data and Theoretical Models
Chaoren Liu
2015-06-01
Full Text Available Relaxation phenomena in glasses are a subject of utmost interest, as they are deeply connected with their structure and dynamics. From a theoretical point of view, mechanical relaxation allows one to get insight into the different atomic-scale processes taking place in the glassy state. Focusing on their possible applications, relaxation behavior influences the mechanical properties of metallic glasses. This paper reviews the present knowledge on mechanical relaxation of metallic glasses. The features of primary and secondary relaxations are reviewed. Experimental data in the time and frequency domain is presented, as well as the different models used to describe the measured relaxation spectra. Extended attention is paid to dynamic mechanical analysis, as it is the most important technique allowing one to access the mechanical relaxation behavior. Finally, the relevance of the relaxation behavior in the mechanical properties of metallic glasses is discussed.
A second gradient theoretical framework for hierarchical multiscale modeling of materials
Luscher, Darby J [Los Alamos National Laboratory; Bronkhorst, Curt A [Los Alamos National Laboratory; Mc Dowell, David L [GEORGIA TECH
2009-01-01
A theoretical framework for the hierarchical multiscale modeling of inelastic response of heterogeneous materials has been presented. Within this multiscale framework, the second gradient is used as a non local kinematic link between the response of a material point at the coarse scale and the response of a neighborhood of material points at the fine scale. Kinematic consistency between these scales results in specific requirements for constraints on the fluctuation field. The wryness tensor serves as a second-order measure of strain. The nature of the second-order strain induces anti-symmetry in the first order stress at the coarse scale. The multiscale ISV constitutive theory is couched in the coarse scale intermediate configuration, from which an important new concept in scale transitions emerges, namely scale invariance of dissipation. Finally, a strategy for developing meaningful kinematic ISVs and the proper free energy functions and evolution kinetics is presented.
Recent advances in the theoretical modeling of pulsating low-mass He-core white dwarfs
Córsico, A H; Calcaferro, L M; Serenelli, A M; Kepler, S O; Jeffery, C S
2016-01-01
Many extremely low-mass (ELM) white-dwarf (WD) stars are currently being found in the field of the Milky Way. Some of these stars exhibit long-period nonradial $g$-mode pulsations, and constitute the class of ELMV pulsating WDs. In addition, several low-mass pre-WDs, which could be precursors of ELM WDs, have been observed to show short-period photometric variations likely due to nonradial $p$ modes and radial modes. They could constitute a new class of pulsating low-mass pre-WD stars, the pre-ELMV stars. Here, we present the recent results of a thorough theoretical study of the nonadiabatic pulsation properties of low-mass He-core WDs and pre-WDs on the basis of fully evolutionary models representative of these stars.
A Theoretical Model for Digital Reverberations of City Spaces and Public Places
Zimmerman, Chris; Hansen, Kjeld; Vatrapu, Ravi
2014-01-01
The increasing pervasiveness of Internet connected devices and services is altering the perception and practice of public spaces through the provisioning of location-specific digital information. Location-aware technologies allow people to access, annotate, address and attach information...... and Mobile technologies that describe and explain crowd-sourced socio-technical layers on the city landscape. The proposed integrated theoretical model describes the relevant information linkages between people and places in the online and offline worlds and introduces a new evaluation method...... for the evaluation of city places: affinity spectrum of social endorsements. The authors conclude with a discussion of the new opportunities for governments to better understand socially emergent ‘urban qualities’ and how citizens construct and appreciate them in order better convert city places into public spaces....
Witkiewitz, Katie; Bowen, Sarah; Harrop, Erin N; Douglas, Haley; Enkema, Matthew; Sedgwick, Carly
2014-04-01
Mindfulness-based treatments are growing in popularity among addiction treatment providers, and several studies suggest the efficacy of incorporating mindfulness practices into the treatment of addiction, including the treatment of substance use disorders and behavioral addictions (i.e., gambling). The current paper provides a review of theoretical models of mindfulness in the treatment of addiction and several hypothesized mechanisms of change. We provide an overview of mindfulness-based relapse prevention (MBRP), including session content, treatment targets, and client feedback from participants who have received MBRP in the context of empirical studies. Future research directions regarding operationalization and measurement, identifying factors that moderate treatment effects, and protocol adaptations for specific populations are discussed.
A Theoretical Model for the Hormetic Dose-response Curve for Anticancer Agents.
Yoshimasu, Tatsuya; Ohashi, Takuya; Oura, Shoji; Kokawa, Yozo; Kawago, Mitsumasa; Hirai, Yoshimitsu; Miyasaka, Miwako; Nishiguchi, Haruka; Kawashima, Sayoko; Yata, Yumi; Honda, Mariko; Fujimoto, Takahiro; Okamura, Yoshitaka
2015-11-01
In the present article, we quantitatively evaluated the dose-response relationship of hormetic reactions of anticancer agents in vitro. Serial dilutions of gemcitabine, cisplatin, 5-fluorouracil, vinorelbine, and paclitaxel were administered to the A549 non-small-cell lung cancer cell line. The bi-phasic sigmoidal curve with hormetic and cytotoxic effects is given by the formula y=(a-b/(1+exp(c(*)log(x)-d)))/(1+exp(e(*)log(x)-f)), that was used to perform a non-linear least square regression. The dose-responses of the five anticancer agents were fitted to this equation. Gemcitabine and 5-fluorouracil, which had the lowest ED50 for their hormetic reaction, had the most pronounced promotive effects out of the five anticancer agents tested. The hormetic reaction progressed exponentially with culturing time. Our theoretical model will be useful in predicting how hormetic reactions affect patients with malignant tumors.
Theoretical investigations on model ternary polypeptides using genetic algorithm—Some new results
Arora, Vinita; Bakhshi, A. K.
2011-04-01
Using genetic algorithm (GA) model ternary polypeptides containing glycine, alanine and serine in β-pleated conformation have been theoretically investigated. In designing, the criterion to attain the optimum solution at the end of GA run is minimum band gap and maximum delocalization in the polypeptide chain. Ab initio results obtained using Clementi's minimal basis set are used as input. Effects of (i) change of basis set from minimal to double zeta, (ii) change in secondary structure from β-pleated to α-helical, (iii) presence of solvation shell and (iv) binding of H + and Li + ions to peptide group on the resulting solution as well as on electronic structure and conduction properties of polypeptides are investigated. A comparison is drawn between results obtained for the two cationic adducts. The protonated adduct is expected to withdraw more negative charge from the polypeptide chain due to smaller size of H + and is found to have high electron affinity compared to Li + adduct.
New results for antiproton-proton elastic scattering and various theoretical models
Fazal-e-Aleem; Saleem, M. (Centre for High Energy Physics, Punjab University, Lahore-54590, Pakistan (PK)); Yodh, G.B. (Department of Physics, University of California-Irvine, Irvine, CA 92717 (USA))
1991-07-01
The most recent measurements of the ratio {rho} of the real and imaginary parts of the forward-scattering amplitudes at 0.546 TeV, the total and elastic differential cross sections at 0.546 and 1.8 TeV for proton-antiproton scattering, are compared to the predictions of the generalized Chou-Yang and other theoretical models. For 1.8 TeV, the presence or absence of the break near {minus}{ital t}{approx}0.15 (GeV/{ital c}){sup 2} and of the dip in the vicinity of 0.6 (GeV/{ital c}){sup 2} are also discussed in the light of various predictions. The possibility of a further rise of the ratio {rho} at 1.8 TeV is also probed.
Theoretical modeling and experimental validation of surface stress in thrombin aptasensor.
Lim, Yang Choon; Kouzani, Abbas Z; Kaynak, Akif; Dai, Xiujuan J; Littlefair, Guy; Duan, Wei
2014-12-01
Adsorption of target molecules on the immobilized microcantilever surface produced beam displacement due to the differential surface stress generated between the immobilized and non-immobilized surface. Surface stress is caused by the intermolecular forces between the molecules. Van der Waals, electrostatic forces, hydrogen bonding, hydrophobic effect and steric hindrance are some of the intermolecular forces involved. A theoretical framework describing the adsorption-induced microcantilever displacement is derived in this paper. Experimental displacement of thrombin aptamer-thrombin interactions was carried out. The relation between the electrostatic interactions involved between adsorbates (thrombin) as well as adsorbates and substrates (thrombin aptamer) and the microcantilever beam displacement utilizing the proposed mathematical model was quantified and compared to the experimental value. This exercise is important to aid the designers in microcantilever sensing performance optimization.
Modeling an Application's Theoretical Minimum and Average Transactional Response Times
Paiz, Mary Rose [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-04-01
The theoretical minimum transactional response time of an application serves as a ba- sis for the expected response time. The lower threshold for the minimum response time represents the minimum amount of time that the application should take to complete a transaction. Knowing the lower threshold is beneficial in detecting anomalies that are re- sults of unsuccessful transactions. On the converse, when an application's response time falls above an upper threshold, there is likely an anomaly in the application that is causing unusual performance issues in the transaction. This report explains how the non-stationary Generalized Extreme Value distribution is used to estimate the lower threshold of an ap- plication's daily minimum transactional response time. It also explains how the seasonal Autoregressive Integrated Moving Average time series model is used to estimate the upper threshold for an application's average transactional response time.
Response of a Grassland Ecosystem to Climate Change in a Theoretical Model
SUN Guodong; MU Mu
2011-01-01
The response of a grassland ecosystem to climate change is discussed within the context of a theoretical model.An optimization approach,a conditional nonlinear optimal perturbation related to parameter (CNOP-P) approach,was employed in this study.The CNOP-P,a perturbation of moisture index in the theoretical model,represents a nonlinear climate perturbation.Two kinds of linear climate perturbations were also used to study the response of the grassland ecosystem to different types of climate changes.The results show that the extent of grassland ecosystem variation caused by the CNOP-P-type climate change is greater than that caused by the two linear types of climate change.In addition,the grassland ecosystem affected by the CNOP-P-type climate change evolved into a desert ecosystem,and the two linear types of climate changes failed within a specific amplitude range when the moisture index recovered to its reference state. Therefore,the grassland ecosystem response to climate change was nonlinear. This study yielded similar results for a desert ecosystem seeded with both living and wilted biomass litter.The quantitative analysis performed in this study also accounted for the role of soil moisture in the root zone and the shading effect of wilted biomass on the grassland ecosystem through nonlinear interactions between soil and vegetation.The results of this study imply that the CNOP-P approach is a potentially effective tool for assessing the impact of nonlinear climate change on grassland ecosystems.
Testik, Firat Yener
An experimental and theoretical study has been conducted to obtain a fundamental understanding of the dynamics of the sand, water and a solid object interaction as progressive gravity waves impinge on a sloping beach. Aside from obvious scientific interest, this exceedingly complex physical problem is important for naval applications, related to the behavior of disk/cylindrical shaped objects (mines) in the coastal waters. To address this problem, it was divided into a set of simpler basic problems. To begin, nonlinear progressive waves were investigated experimentally in a wave tank for the case of a rigid (impermeable) sloping bottom. Parameterizations for wave characteristics were proposed and compared with the experiments. In parallel, a numerical wave tank model (NWT) was calibrated using experimental data from a single run, and wave field in the wave tank was simulated numerically for the selected experiments. Subsequently, a layer of sand was placed on the slope and bottom topography evolution processes (ripple and sandbar dynamics, bottom topography relaxation under variable wave forcing, etc.) were investigated experimentally. Models for those processes were developed and verified by experimental measurements. Flow over a circular cylinder placed horizontally on a plane wall was also studied. The far-flow field of the cylinder placed in the wave tank was investigated experimentally and numerical results from the NWT simulations were compared with the experimental data. In the mean time, the near-flow velocity/vorticity field around a short cylinder under steady and oscillatory flow was studied in a towing tank. Horseshoe vortex formation and periodic shedding were documented and explained. With the understanding gained through the aforementioned studies, dynamics and burial/scour around the bottom objects in the wave tank were studied. Possible scenarios on the behavior of the disk-shaped objects were identified and explained. Scour around 3D cylindrical
Karimi, Leila; Ghassemi, Abbas
2016-07-01
Among the different technologies developed for desalination, the electrodialysis/electrodialysis reversal (ED/EDR) process is one of the most promising for treating brackish water with low salinity when there is high risk of scaling. Multiple researchers have investigated ED/EDR to optimize the process, determine the effects of operating parameters, and develop theoretical/empirical models. Previously published empirical/theoretical models have evaluated the effect of the hydraulic conditions of the ED/EDR on the limiting current density using dimensionless numbers. The reason for previous studies' emphasis on limiting current density is twofold: 1) to maximize ion removal, most ED/EDR systems are operated close to limiting current conditions if there is not a scaling potential in the concentrate chamber due to a high concentration of less-soluble salts; and 2) for modeling the ED/EDR system with dimensionless numbers, it is more accurate and convenient to use limiting current density, where the boundary layer's characteristics are known at constant electrical conditions. To improve knowledge of ED/EDR systems, ED/EDR models should be also developed for the Ohmic region, where operation reduces energy consumption, facilitates targeted ion removal, and prolongs membrane life compared to limiting current conditions. In this paper, theoretical/empirical models were developed for ED/EDR performance in a wide range of operating conditions. The presented ion removal and selectivity models were developed for the removal of monovalent ions and divalent ions utilizing the dominant dimensionless numbers obtained from laboratory scale electrodialysis experiments. At any system scale, these models can predict ED/EDR performance in terms of monovalent and divalent ion removal.
Theoretical investigations on model ternary polypeptides using genetic algorithm-Some new results
Arora, Vinita [Department of Chemistry, University of Delhi, Delhi 110 007 (India); Bakhshi, A.K., E-mail: akbakhshi2000@yahoo.com [Department of Chemistry, University of Delhi, Delhi 110 007 (India)
2011-04-28
Graphical abstract: Model ternary polypeptide chains consisting of glycine, alanine and serine amino acids as repeat units in anti-parallel {beta}-pleated sheet conformation have been theoretically investigated and designed using the genetic algorithm. The optimum solution or the polypeptide chain being searched for using the algorithm is the one having minimum band gap and maximum electronic delocalization in the polypeptide chain. The effects of (i) change of basis set from minimal to double zeta, (ii) change in secondary structure from {beta}-pleated to {alpha}-helical, (iii) presence of solvation shell, and (iv) binding of ions such as H{sup +} and Li{sup +} to the peptide group on the resulting optimum solution as well as on electronic structure and conduction properties of polypeptides have been investigated taking the ab initio Hartree-Fock crystal orbital results as input. The band gap value was also found to decrease in presence of a solvation shell, in presence of cations in the vicinity of the polypeptide chain as well as with the use of an improved basis set. Highlights: {yields} GA has been used for theoretical tailoring of aperiodic ternary polypeptides. {yields} Band gap of polypeptide chain decreases in presence of solvation shell. {yields} Band gap decreases in presence of cations in the vicinity of the chain. {yields} H{sup +} ion acts as a strong electron acceptor than Li{sup +} ion due to smaller size. - Abstract: Using genetic algorithm (GA) model ternary polypeptides containing glycine, alanine and serine in {beta}-pleated conformation have been theoretically investigated. In designing, the criterion to attain the optimum solution at the end of GA run is minimum band gap and maximum delocalization in the polypeptide chain. Ab initio results obtained using Clementi's minimal basis set are used as input. Effects of (i) change of basis set from minimal to double zeta, (ii) change in secondary structure from {beta}-pleated to {alpha
Theoretical models of mercury dissolution from dental amalgams in neutral and acidic flows
Keanini, Russell G.; Ferracane, Jack L.; Okabe, Toru
2001-06-01
This article reports an experimental and theoretical investigation of mercury dissolution from dental amalgams immersed in neutral (noncorrosive) and acidic (corrosive) flows. Atomic absorption spectrophotometric measurements of Hg loss indicate that in neutral flow, surface oxide films formed in air prior to immersion persist and effectively suppress significant mercury release. In acidic (pH 1) flows, by contrast, oxide films are unstable and dissolve; depending on the amalgam’s material composition, particularly its copper content, two distinct mercury release mechanisms are initiated. In low copper amalgam, high initial mercury release rates are observed and appear to reflect preferential mercury dissolution from unstable Sn8Hg ( γ 2) grains within the amalgam matrix. In high copper amalgam, mercury release rates are initially low, but increase with time. Microscopic examination suggests that this feature reflects corrosion of copper from grains of Cu6Sn5 ( η') and consequent exposure of Ag2Hg3 ( γ 1) grains; the latter serve as internal mercury release sites and become more numerous as corrosion proceeds. Three theoretical models are proposed in order to explain observed dissolution characteristics. Model I, applicable to high and low copper amalgams in neutral flow, assumes that mercury dissolution is mediated by solid diffusion within the amalgam, and that a thin oxide film persists on the amalgam’s surface and lumps diffusive in-film transport into an effective convective boundary condition. Model II, applicable to low copper amalgam in acidic flow, assumes that the amalgam’s external oxide film dissolves on a short time scale relative to the experimental observation period; it neglects corrosive suppression of mercury transport. Model III, applicable to high copper amalgam in acidic flow, assumes that internal mercury release sites are created by corrosion of copper in η' grains and that corrosion proceeds via an oxidation-reduction reaction
Yan Hanjie; Yan Hong; Li Yunping; Zhang Xiaofeng
2003-01-01
As gravity field, magnetic field, electric field and reismic wave field are all physical fields, their object function, reverse function and compound function are certainly infinite continuously differentiable functions which can be expanded into Taylor (Fourier) series within domain of definition and be further reduced into solving stochastic distribution function of series and statistic inference of optimal approximation. This is thebasis of combined gravity-magnetic-electric-seismic inversion of stochastic modeling. It is an uncertainty modeling technology of combining gravity-magnetic-electric-seismic inversion built on the basis of separation of field and source gravity-magnetic difference-value (D-value) trend surface, taking distribution-independent fault system as its unit, depths of seismic and electric interfaces of interests as its corresponding bivariate compound reverse function of gravity-magnetic anomalies and using high order polynomial (high order trigonometric function) approximating to its series distribution. The difference from current dominant inversion techniques is that, first, it does not respectively create gravity-seismic, magnetic-seismic deterministic inversion model from theoretical model, but combines gravity-magnetic-electric-seismic stochastic inversion model from stochastic model; second, after the concept of equivalent geological body being introduced, using feature of independent variable of gravity-magnetic field functions, taking density and susceptibility related to gravity-magnetic function as default parameters of model, the deterministic model is established owing to better solution to the contradiction of difficulty in identifying strata and less test analytical data for density and susceptibility in newly explored area; third, under assumption of independent parent distribution, a real modeling by strata, the problem of difficult plane closure arising in profile modeling is avoided. This technology has richer and more
Theoretical models for the regulation of DNA replication in fast-growing bacteria
Creutziger, Martin; Schmidt, Mischa; Lenz, Peter
2012-09-01
Growing in always changing environments, Escherichia coli cells are challenged by the task to coordinate growth and division. In particular, adaption of their growth program to the surrounding medium has to guarantee that the daughter cells obtain fully replicated chromosomes. Replication is therefore to be initiated at the right time, which is particularly challenging in media that support fast growth. Here, the mother cell initiates replication not only for the daughter but also for the granddaughter cells. This is possible only if replication occurs from several replication forks that all need to be correctly initiated. Despite considerable efforts during the last 40 years, regulation of this process is still unknown. Part of the difficulty arises from the fact that many details of the relevant molecular processes are not known. Here, we develop a novel theoretical strategy for dealing with this general problem: instead of analyzing a single model, we introduce a wide variety of 128 different models that make different assumptions about the unknown processes. By comparing the predictions of these models we are able to identify the key quantities that allow the experimental discrimination of the different models. Analysis of these quantities yields that out of the 128 models 94 are not consistent with available experimental data. From the remaining 34 models we are able to conclude that mass growth and DNA replication need either to be truly coupled, by coupling DNA replication initiation to the event of cell division, or to the amount of accumulated mass. Finally, we make suggestions for experiments to further reduce the number of possible regulation scenarios.
Decay widths of bottomonium states in matter -- a field theoretic model for composite hadrons
Mishra, Amruta
2016-01-01
We compute the in-medium partial decay widths of the bottomonium states to open bottom mesons ($B\\bar B$) using a field theoretical model for composite hadrons with quark constituents. These decay widths are calculated by using the explicit constructions for the bottomonium states and the open bottom mesons ($B$ and $\\bar B$), and, the quark antiquark pair creation term of the free Dirac Hamiltonian written in terms of the constituent quark field operators. These decay widths are calculated as arising from the mass modifications of the bottomonium states and the $B$ and $\\bar B$ mesons, obtained in a chiral effective model. The decay amplitude in the present model is multiplied with a strength parameter for the light quark pair creation, which is fitted from the observed vacuum partial decay width of the bottomonium state, $\\Upsilon (4S)$ to $B\\bar B$. The effects of the isospin asymmetry, the strangeness fraction of the hadronic matter on the decay widths, arising due to the mass modifications due to these e...
Charmonium decay widths in matter in a field theoretic model of composite hadrons
Mishra, Amruta
2013-01-01
We calculate the decay widths of the charmonium states, $J/\\psi$, $\\psi (3686)$ and $\\psi(3770)$, to $D\\bar D$ pairs in isospin asymmetric strange hadronic matter, using a field theoretical model for composite hadrons with quark constituents. For this purpose we use a quark antiquark pair creation term that arises within the model, and then use explicit charmonium and $D$ and $\\bar {D}$ states to evaluate the decay amplitudes. The medium modifications of these partial decay widths, arising from the mass modifications of the $D(\\bar D)$ and the charmonium states calculated in a chiral effective model, are also included. The results of the present investigations are then compared with the decay widths computed earlier, using an ad hoc light quark pair creation in $^3P_0$ state. The effects of the isospin asymmetry, the strangeness fraction of the hadronic matter on the masses of the charmonium states and $D(\\bar D)$ mesons and hence on the decay widths, have also been studied. The isospin asymmetry effect is ob...