Theoretical model of laminar flow in a channel or tube under ocean conditions
International Nuclear Information System (INIS)
Yan, B.H.; Yu, L.; Yang, Y.H.
2011-01-01
Research highlights: → The theoretical model of laminar flow in channels under ocean conditions is established. → The frictional resistance coefficient and Nusselt number are also obtained. → The theoretical results are in agreement with experimental data. → The oscillation of parameters is induced by the tangential force. -- Abstract: The theoretical model of laminar flow in a channel or tube under ocean conditions is established. The velocity and temperature correlations are derived, and the frictional resistance coefficient and Nusselt number are also obtained. The theoretical results are in agreement with experimental data. The oscillation of parameters is induced by the tangential force due to ocean conditions. The effect of centrifugal and Coriolis forces on the flow is negligible. The effects of several parameters on the frictional resistance coefficient and Nusselt number are investigated. The oscillating amplitude of Nusselt number increases with the increasing of Prandtl number. Both the oscillating amplitudes of frictional resistance coefficient and Nusselt number increase with the increasing of rolling frequency.
Theoretical modeling of mechanical homeostasis of a mammalian cell under gravity-directed vector.
Zhou, Lüwen; Zhang, Chen; Zhang, Fan; Lü, Shouqin; Sun, Shujin; Lü, Dongyuan; Long, Mian
2018-02-01
Translocation of dense nucleus along gravity vector initiates mechanical remodeling of a eukaryotic cell. In our previous experiments, we quantified the impact of gravity vector on cell remodeling by placing an MC3T3-E1 cell onto upward (U)-, downward (D)-, or edge-on (E)- orientated substrate. Our experimental data demonstrate that orientation dependence of nucleus longitudinal translocation is positively correlated with cytoskeletal (CSK) remodeling of their expressions and structures and also is associated with rearrangement of focal adhesion complex (FAC). However, the underlying mechanism how CSK network and FACs are reorganized in a mammalian cell remains unclear. In this paper, we developed a theoretical biomechanical model to integrate the mechanosensing of nucleus translocation with CSK remodeling and FAC reorganization induced by a gravity vector. The cell was simplified as a nucleated tensegrity structure in the model. The cell and CSK filaments were considered to be symmetrical. All elements of CSK filaments and cytomembrane that support the nucleus were simplified as springs. FACs were simplified as an adhesion cluster of parallel bonds with shared force. Our model proposed that gravity vector-directed translocation of the cell nucleus is mechanically balanced by CSK remodeling and FAC reorganization induced by a gravitational force. Under gravity, dense nucleus tends to translocate and exert additional compressive or stretching force on the cytoskeleton. Finally, changes of the tension force acting on talin by microfilament alter the size of FACs. Results from our model are in qualitative agreement with those from experiments.
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
A theoretical model of the evolution of maternal effects under parent-offspring conflict
Uller, Tobias; Pen, Ido
The evolution of maternal effects on offspring phenotype should depend on the extent of parent-offspring conflict and costs and constraints associated with maternal and offspring strategies. Here, we develop a model of maternal effects on offspring dispersal phenotype under parent-offspring conflict
A theoretical model of virtual water trade under increasing water scarcity conditions
de Vos, Lotte; Pande, Saket
2016-04-01
This paper proposes a virtual water trade model to obtain a better understanding of how hydro-climatic change affects societies through changes in virtual water trade. In previous studies it has been shown that global trade patterns can be influenced by water scarcity and vice-versa. The extent to which this relationship holds is still a topic under discussion. With the model introduced in this paper, the dynamics behind these trade patterns are further explored. First, a model is constructed of a society suffering from an increase in water scarcity. This model is shown to be capable of replicating patterns of technological, population, production and consumption per capita changes. In order to incorporate the effects of globalization and trade, the model has been extended to a toy model of virtual water trade between two societies. The two societies are represented by overlapping generations models. The individuals of each generation provide the labour needed for the production of the composite goods. In addition to this labour, water and technology are also incorporated as factors of production. There are two goods being produced; one is labour intensive and the other water intensive. Trade emerges from the principle of comparative advantage, with differences in labour-abundance and water resources availability between the two societies. Using this model of two societies interconnected by trade, it is examined how trade of water-intensive commodities alters under changing scarcity conditions. In particular we explore the conditions under which trade emerges, and to what extent. Furthermore, we present the conditions for the sustainable development within these two societies.
Directory of Open Access Journals (Sweden)
Jingwen Mo
2017-09-01
Full Text Available Effective thermal conductivity experiments were carried out with spherical particle beds under low and high compressive pressure loading in vacuum and air. A theoretical model was proposed for the effective thermal conductivity of particle beds based on the experimental results. The model incorporates heat conduction by particles including contact thermal resistance between particles, conduction through the gas in between particles, and radiation between particles, and includes two fitting parameters, namely the coefficient of heat conducted through the fluid, and the macro-contact thermal resistance. The predictions from the theoretical model satisfactorily match the experimental data for the bed effective thermal conductivity over the range of applied loading pressures on particles with different Young's modulus and the gas environment. The model can be used generally to describe the effect of compression stress or pressure on effective thermal conductivity of particle beds.
The quantization of the attention function under a Bayes information theoretic model
International Nuclear Information System (INIS)
Wynn, H.P.; Sebastiani, P.
2001-01-01
Bayes experimental design using entropy, or equivalently negative information, as a criterion is fairly well developed. The present work applies this model but at a primitive level in statistical sampling. It is assumed that the observer/experimentor is allowed to place a window over the support of a sampling distribution and only 'pay for' observations that fall in this window. The window can be modeled with an 'attention function', simply the indicator function of the window. The understanding is that the cost of the experiment is only the number of paid for observations: n. For fixed n and under the information model it turns out that for standard problems the optimal structure for the window, in the limit amongst all types of window including disjoint regions, is discrete. That is to say it is optimal to observe the world (in this sense) through discrete slits. It also shows that in this case Bayesians with different priors will receive different samples because typically the optimal attention windows will be disjoint. This property we refer to as the quantization of the attention function
Rashidi Moghaddam, M.; Ayatollahi, M. R.; Berto, F.
2018-01-01
The values of mode II fracture toughness reported in the literature for several rocks are studied theoretically by using a modified criterion based on strain energy density averaged over a control volume around the crack tip. The modified criterion takes into account the effect of T-stress in addition to the singular terms of stresses/strains. The experimental results are related to mode II fracture tests performed on the semicircular bend and Brazilian disk specimens. There are good agreements between theoretical predictions using the generalized averaged strain energy density criterion and the experimental results. The theoretical results reveal that the value of mode II fracture toughness is affected by the size of control volume around the crack tip and also the magnitude and sign of T-stress.
A theoretical model for oxygen transport in skeletal muscle under conditions of high oxygen demand.
McGuire, B J; Secomb, T W
2001-11-01
Oxygen transport from capillaries to exercising skeletal muscle is studied by use of a Krogh-type cylinder model. The goal is to predict oxygen consumption under conditions of high demand, on the basis of a consideration of transport processes occurring at the microvascular level. Effects of the decline in oxygen content of blood flowing along capillaries, intravascular resistance to oxygen diffusion, and myoglobin-facilitated diffusion are included. Parameter values are based on human skeletal muscle. The dependence of oxygen consumption on oxygen demand, perfusion, and capillary density are examined. When demand is moderate, the tissue is well oxygenated and consumption is slightly less than demand. When demand is high, capillary oxygen content declines rapidly with axial distance and radial oxygen transport is limited by diffusion resistance within the capillary and the tissue. Under these conditions, much of the tissue is hypoxic, consumption is substantially less than demand, and consumption is strongly dependent on capillary density. Predicted consumption rates are comparable with experimentally observed maximal rates of oxygen consumption.
A Game Theoretical Model for Location of Terror Response Facilities under Capacitated Resources
Directory of Open Access Journals (Sweden)
Lingpeng Meng
2013-01-01
Full Text Available This paper is concerned with the effect of capacity constraints on the locations of terror response facilities. We assume that the state has limited resources, and multiple facilities may be involved in the response until the demand is satisfied consequently. We formulate a leader-follower game model between the state and the terrorist and prove the existence and uniqueness of the Nash equilibrium. An integer linear programming is proposed to obtain the equilibrium results when the facility number is fixed. The problem is demonstrated by a case study of the 19 districts of Shanghai, China.
International Nuclear Information System (INIS)
Green, W.J.
1987-04-01
Simple theoretical models have been developed which are suitable for predicting the thermal responses of irradiated research fuel elements of markedly different geometries when they are subjected to loss-of-coolant accident conditions. These models have been used to calculate temperature responses corresponding to various non-forced convective conditions. Comparisons between experimentally observed temperatures and calculated values have shown that a suitable value for surface thermal emissivity is 0.35; modelling of the fuel element beyond the region of the fuel plate needs to be included since these areas account for approximately 25 per cent of the thermal power dissipated; general agreement between calculated and experimental temperatures for both transient and steady-state conditions is good - the maximum discrepancy between calculated and experimental temperatures for a HIFAR Mark IV/V fuel element is ∼ 70 deg C, and for an Oak Ridge Reactor (ORR) box-type fuel element ∼ 30 deg C; and axial power distribution does not significantly affect thermal responses for the conditions investigated. Overall, the comparisons have shown that the models evolved can reproduce experimental data to a level of accuracy that provides confidence in the modelling technique and the postulated heat dissipation mechanisms, and that these models can be used to predict thermal responses of fuel elements in accident conditions that are not easily investigated experimentally
Directory of Open Access Journals (Sweden)
Michael Fröhlich
2013-10-01
Full Text Available In Olympic-distance triathlon, time minimization is the goal in all three disciplines and the two transitions. Running is the key to winning, whereas swimming and cycling performance are less significantly associated with overall competition time. A comparative static simulation calculation based on the individual times of each discipline was done. Furthermore, the share of the discipline in the total time proved that increasing the scope of running training results in an additional performance development. Looking at the current development in triathlon and taking the Olympic Games in London 2012 as an initial basis for model-theoretic simulations of performance development, the first fact that attracts attention is that running becomes more and more the crucial variable in terms of winning a triathlon. Run times below 29:00 minutes in Olympic-distance triathlon will be decisive for winning. Currently, cycle training time is definitely overrepresented. The share of swimming is considered optimal.
Franchise Business Model: Theoretical Insights
Levickaitė, Rasa; Reimeris, Ramojus
2010-01-01
The article is based on literature review, theoretical insights, and deals with the topic of franchise business model. The objective of the paper is to analyse peculiarities of franchise business model and its developing conditions in Lithuania. The aim of the paper is to make an overview on franchise business model and its environment in Lithuanian business context. The overview is based on international and local theoretical insights. In terms of practical meaning, this article should be re...
Theoretical models for supernovae
International Nuclear Information System (INIS)
Woosley, S.E.; Weaver, T.A.
1981-01-01
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 γ-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 4 He and 14 N prior to their collapse on the pair instability
Theoretical Modeling for the X-ray Spectroscopy of Iron-bearing MgSiO3 under High Pressure
Wang, X.; Tsuchiya, T.
2012-12-01
The behaviors of iron (Fe) in MgSiO3 perovskite, including valence state, spin state, and chemical environments, at high pressures are of fundamental importance for more detailed understanding the properties of the Earth's lower mantle. The pressure induced spin transition of Fe-bearing MgO and MgSiO3 are detected often by using high-resolution K-edge X-ray emission spectroscopy (XES) [1,2,3] and confirmed by theoretical simulations. [4,5] Since the Fe K-edge XES is associated to the 3p orbital, which is far from the valence orbitals (3d and 4s), it provides no information about its coordination environments. However, the Fe L-edge XES and X-ray absorption spectroscopy (XAS) can directly present the distribution and intensity of Fe-3d character. To identify both the spin states and the coordination environments of iron-bearing MgSiO3, we systematically investigate the L-edge XAS, XES and X-ray photoelectron (XPS) spectroscopy of Fe2+- and Fe3+-bearing MgSiO3 under high pressure by using the first-principles density functional method combined with the slater-transition method. Our results show that Fe2+ and Fe3+ can be distinguished easily by taking the XPS spectra. The spin transition of Fe2+ and Fe3+ can also be clearly certified by XAS and XES. Interestingly, the broadness of L-edge XES of Fe changes depending on the iron position, meaning that its coordination environment might also be distinguishable by using high-resolution XES measurements. Research supported by the Ehime University G-COE program and KAKENHI. [1] James Badro, Guillaume Fiquet, FranÇois Guyot, Jean-Pascal Rueff, Viktor V. Struzhkin, György VankÓ, and Giulio Monaco. Science 300, 789 (2003), [2] James Badro, Jean-Pascal Rueff, György VankÓ, Giulio Monaco, Guillaume Fiquet, and FranÇois Guyot, Science 305, 383 (2004), [3] Jung-Fu Lin, Viktor V. Struzhkin, Steven D. Jacobsen, Michael Y. Hu, Paul Chow, Jennifer Kung, Haozhe Liu, Ho-kwang Mao, and Gussell J. Hemley, Nature 436, 377 (2005). [4
Energy Technology Data Exchange (ETDEWEB)
Kohandani, R; Kaatuzian, H [Photonics Research Laboratory, Electrical Engineering Department, AmirKabir University of Technology, Hafez Ave., Tehran (Iran, Islamic Republic of)
2015-01-31
We report a theoretical study of optical properties of AlGaAs/GaAs multiple quantum-well (MQW), slow-light devices based on excitonic population oscillations under applied external magnetic and electric fields using an analytical model for complex dielectric constant of Wannier excitons in fractional dimension. The results are shown for quantum wells (QWs) of different width. The significant characteristics of the exciton in QWs such as exciton energy and exciton oscillator strength (EOS) can be varied by application of external magnetic and electric fields. It is found that a higher bandwidth and an appropriate slow-down factor (SDF) can be achieved by changing the QW width during the fabrication process and by applying magnetic and electric fields during device functioning, respectively. It is shown that a SDF of 10{sup 5} is obtained at best. (slowing of light)
Grassi, Alba; Mariño, Marcos
2015-02-01
Some matrix models admit, on top of the usual 't Hooft expansion, an M-theory-like expansion, i.e. an expansion at large N but where the rest of the parameters are fixed, instead of scaling with N . These models, which we call M-theoretic matrix models, appear in the localization of Chern-Simons-matter theories, and also in two-dimensional statistical physics. Generically, their partition function receives non-perturbative corrections which are not captured by the 't Hooft expansion. In this paper, we discuss general aspects of these type of matrix integrals and we analyze in detail two different examples. The first one is the matrix model computing the partition function of supersymmetric Yang-Mills theory in three dimensions with one adjoint hypermultiplet and N f fundamentals, which has a conjectured M-theory dual, and which we call the N f matrix model. The second one, which we call the polymer matrix model, computes form factors of the 2d Ising model and is related to the physics of 2d polymers. In both cases we determine their exact planar limit. In the N f matrix model, the planar free energy reproduces the expected behavior of the M-theory dual. We also study their M-theory expansion by using Fermi gas techniques, and we find non-perturbative corrections to the 't Hooft expansion.
Theoretical models of DNA flexibility
Czech Academy of Sciences Publication Activity Database
Dršata, Tomáš; Lankaš, Filip
2013-01-01
Roč. 3, č. 4 (2013), s. 355-363 ISSN 1759-0876 Institutional support: RVO:61388963 Keywords : molecular dynamics simulations * base pair level * indirect readout Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 9.041, year: 2013
Parameters and error of a theoretical model
International Nuclear Information System (INIS)
Moeller, P.; Nix, J.R.; Swiatecki, W.
1986-09-01
We propose a definition for the error of a theoretical model of the type whose parameters are determined from adjustment to experimental data. By applying a standard statistical method, the maximum-likelihoodlmethod, we derive expressions for both the parameters of the theoretical model and its error. We investigate the derived equations by solving them for simulated experimental and theoretical quantities generated by use of random number generators. 2 refs., 4 tabs
A theoretical model of water and trade
Dang, Qian; Konar, Megan; Reimer, Jeffrey J.; Di Baldassarre, Giuliano; Lin, Xiaowen; Zeng, Ruijie
2016-03-01
Water is an essential input for agricultural production. Agriculture, in turn, is globalized through the trade of agricultural commodities. In this paper, we develop a theoretical model that emphasizes four tradeoffs involving water-use decision-making that are important yet not always considered in a consistent framework. One tradeoff focuses on competition for water among different economic sectors. A second tradeoff examines the possibility that certain types of agricultural investments can offset water use. 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 commodities. The fourth tradeoff concerns how variability in water supplies influences farmer decision-making. We show conditions under which trade liberalization affect water use. Two policy scenarios to reduce water use are evaluated. First, we derive a target tax that reduces water use without offsetting the gains from trade liberalization, although important tradeoffs exist between economic performance and resource use. Second, we show how subsidization of water-saving technologies can allow producers to use less water without reducing agricultural production, making such subsidization an indirect means of influencing water use decision-making. Finally, we outline conditions under which riskiness of water availability affects water use. These theoretical model results generate hypotheses that can be tested empirically in future work.
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.
Theoretical Models for Orthogonal Cutting
DEFF Research Database (Denmark)
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.”...
Modeling Heliospheric Interface: Observational and Theoretical Challenges
Pogorelov, N.; Heerikhuisen, J.; Borovikov, S.; Zank, G.
2008-12-01
Observational data provided by Voyager 1 and Voyager 2 spacecraft ahead of the heliospheric termination shock (TS) and in the heliosheath require considerate reassessment of theoretical models of the solar wind (SW) interaction with the magnetized interstellar medium (LISM). Contemporary models, although sophisticated enough to take into account kinetic processes accompanying charge exchange between ions and atoms and address the coupling of the interstellar and interplanetary magnetic fields (ISMF and IMF) at the heliospheric interface, are still unable to analyze the effect of non-thermal pick-up ions (PUI's) in the heliosheath. The presence of PUI's undermines the assumption of a Maxwellian distribution of the SW ions. We discuss the ways to improve physical models in this respect. The TS asymmetry observed by Voyagers can be attributed to the combination of 3D, time- dependent behavior of the SW and by the action of the ISMF. It is clear, however, that the ISMF alone can account for the TS asymmetry of about 10 AU only if it is unexpectedly strong (greater than 4 microgauss). We analyze the consequences of such magnetic fields for the neutral hydrogen deflection in the inner heliosphere from its original direction in the unperturbed LISM. We also discuss the conditions for the 2-3 kHz radio emission, which is believed to be generated in the outer heliosheath beyond the heliopause, and analyze possible location of radio emission sources under the assumption of strong magnetic field. The quality of the physical model becomes crucial when we need to address modern observational and theoretical challenges. We compare the plasma, neutral particle, and magnetic field distributions obtained with our MHD-kinetic and 5-fluid models. The transport of neutral particles is treated kinetically in the former and by a multiple neutral-fluid approach in the latter. We also investigate the distribution of magnetic field in the inner heliosheath for large angles between the Sun
Toward a theoretical model for mindfulness-based pain management.
Day, Melissa A; Jensen, Mark P; Ehde, Dawn M; Thorn, Beverly E
2014-07-01
Mindfulness, as both a process and a practice, has received substantial research attention across a range of health conditions, including chronic pain. Previously proposed mechanisms underlying the potential health-related benefits of mindfulness and mindfulness-based interventions (MBIs) are based on a strong theoretical background. However, to date, an empirically grounded, integrated theoretical model of the mechanisms of MBIs within the context of chronic pain has yet to be proposed. This is a surprising gap in the literature given the exponential growth of studies reporting on the benefits of MBIs for heterogeneous chronic pain conditions. Moreover, given the importance of determining how, and for whom, psychological interventions for pain management are effective, it is imperative that this gap in the literature be addressed. The overarching aim of the current theoretical paper was to propose an initial integrated, theoretically driven, and empirically based model of the mechanisms of MBIs for chronic pain management. Theoretical and research implications of the model are discussed. The theoretical considerations proposed herein can be used to help organize and guide future research that will identify the mechanisms underlying the benefits of mindfulness-based treatments, and perhaps psychosocial treatments more broadly, for chronic pain management. This focus article presents an initial framework for an empirically based, theoretical model of the mechanisms of MBIs for chronic pain management. Implications of the framework for refining theory and for future research are addressed. Copyright © 2014 American Pain Society. Published by Elsevier Inc. All rights reserved.
A Set Theoretical Approach to Maturity Models
DEFF Research Database (Denmark)
Lasrado, Lester; Vatrapu, Ravi; Andersen, Kim Normann
2016-01-01
of it application on a social media maturity data-set. Specifically, we employ Necessary Condition Analysis (NCA) to identify maturity stage boundaries as necessary conditions and Qualitative Comparative Analysis (QCA) to arrive at multiple configurations that can be equally effective in progressing to higher......Maturity Model research in IS has been criticized for the lack of theoretical grounding, methodological rigor, empirical validations, and ignorance of multiple and non-linear paths to maturity. To address these criticisms, this paper proposes a novel set-theoretical approach to maturity models...... characterized by equifinality, multiple conjunctural causation, and case diversity. We prescribe methodological guidelines consisting of a six-step procedure to systematically apply set theoretic methods to conceptualize, develop, and empirically derive maturity models and provide a demonstration...
Modeling scientific: some theoretical and methodological considerations
Directory of Open Access Journals (Sweden)
Carlos Tamayo-Roca
2017-04-01
Full Text Available At present widespread use of models as an auxiliary system to penetrate the essence of phenomena related to all areas of cognitive and transforming activity of man, covering as diverse as human sciences fields. In the field of education use it is becoming more common as essential to transform school practice and enrich their theoretical instrument bitter day. The paper deals with the development of theoretical modeling as a scientific method to advance the process to be transformed and characterized by establishing relationships and links between the structural components that comprise it. In this regard it is proposed as an objective socialize some theoretical and methodological considerations that favor the use of modeling method in the scientific research activity of teachers.
Theoretical models for recombination in expanding gas
International Nuclear Information System (INIS)
Avron, Y.; Kahane, S.
1978-09-01
In laser isotope separation of atomic uranium, one is confronted with the theoretical problem of estimating the concentration of thermally ionized uranium atoms. To investigate this problem theoretical models for recombination in an expanding gas and in the absence of local thermal equilibrium have been constructed. The expansion of the gas is described by soluble models of the hydrodynamic equation, and the recombination by rate equations. General results for the freezing effect for the suitable ranges of the gas parameters are obtained. The impossibility of thermal equilibrium in expanding two-component systems is proven
Modeling business processes: theoretical and practical aspects
Directory of Open Access Journals (Sweden)
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.
Determination of cognitive development: postnonclassical theoretical model
Directory of Open Access Journals (Sweden)
Irina N. Pogozhina
2015-09-01
Full Text Available The aim of this research is to develop a postnonclassical cognitive processes content determination model in which mental processes are considered as open selfdeveloping, self-organizing systems. Three types of systems (dynamic, statistical, developing were analysed and compared on the basis of the description of the external and internal characteristics of causation, types of causal chains (dependent, independent and their interactions, as well as the nature of the relationship between the elements of the system (hard, probabilistic, mixed. Mechanisms of open non-equilibrium nonlinear systems (dissipative and four dissipative structures emergence conditions are described. Determination models of mental and behaviour formation and development that were developed under various theoretical approaches (associationism, behaviorism, gestaltism, psychology of intelligence by Piaget, Vygotsky culture historical approach, activity approach and others are mapped on each other as the models that describe behaviour of the three system types mentioned above. The development models of the mental sphere are shown to be different by the following criteria: 1 allocated determinants amount; 2 presence or absence of the system own activity that results in selecting the model not only external, but also internal determinants; 3 types of causal chains (dependent-independent-blended; 4 types of relationships between the causal chain that ultimately determines the subsequent system determination type as decisive (a tough dynamic pattern or stochastic (statistical regularity. The continuity of postnonclassical, classical and non-classical models of mental development determination are described. The process of gradual refinement, complexity, «absorption» of the mental determination by the latter models is characterized. The human mental can be deemed as the functioning of the open developing non-equilibrium nonlinear system (dissipative. The mental sphere is
A theoretical model of multielectrode DBR lasers
DEFF Research Database (Denmark)
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...
Hybrid quantum teleportation: A theoretical model
Energy Technology Data Exchange (ETDEWEB)
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.
A field theoretic model for static friction
Mahyaeh, I.; Rouhani, S.
2013-01-01
We present a field theoretic model for friction, where the friction coefficient between two surfaces may be calculated based on elastic properties of the surfaces. We assume that the geometry of contact surface is not unusual. We verify Amonton's laws to hold that friction force is proportional to the normal load.This model gives the opportunity to calculate the static coefficient of friction for a few cases, and show that it is in agreement with observed values. Furthermore we show that the ...
Structural stability and theoretical strength of Cu crystal under equal ...
Indian Academy of Sciences (India)
The results indicate that, under sufficient tension, there exists a stress-free BCC phase which is unstable and slips spontaneously to a stress-free metastable BCT phase by consuming internal energy. The stable region ranges from −15.131 GPa to 2.803 GPa in the theoretical strength or from −5.801% to 4.972% in the strain ...
Information-Theoretic Perspectives on Geophysical Models
Nearing, Grey
2016-04-01
To test any hypothesis about any dynamic system, it is necessary to build a model that places that hypothesis into the context of everything else that we know about the system: initial and boundary conditions and interactions between various governing processes (Hempel and Oppenheim, 1948, Cartwright, 1983). No hypothesis can be tested in isolation, and no hypothesis can be tested without a model (for a geoscience-related discussion see Clark et al., 2011). Science is (currently) fundamentally reductionist in the sense that we seek some small set of governing principles that can explain all phenomena in the universe, and such laws are ontological in the sense that they describe the object under investigation (Davies, 1990 gives several competing perspectives on this claim). However, since we cannot build perfect models of complex systems, any model that does not also contain an epistemological component (i.e., a statement, like a probability distribution, that refers directly to the quality of of the information from the model) is falsified immediately (in the sense of Popper, 2002) given only a small number of observations. Models necessarily contain both ontological and epistemological components, and what this means is that the purpose of any robust scientific method is to measure the amount and quality of information provided by models. I believe that any viable philosophy of science must be reducible to this statement. The first step toward a unified theory of scientific models (and therefore a complete philosophy of science) is a quantitative language that applies to both ontological and epistemological questions. Information theory is one such language: Cox' (1946) theorem (see Van Horn, 2003) tells us that probability theory is the (only) calculus that is consistent with Classical Logic (Jaynes, 2003; chapter 1), and information theory is simply the integration of convex transforms of probability ratios (integration reduces density functions to scalar
Modelling in Accounting. Theoretical and Practical Dimensions
Directory of Open Access Journals (Sweden)
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.
Organizational Resilience: The Theoretical Model and Research Implication
Directory of Open Access Journals (Sweden)
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.
Theoretical models of neutron emission in fission
International Nuclear Information System (INIS)
Madland, D.G.
1992-01-01
A brief survey of theoretical representations of two of the observables in neutron emission in fission is given, namely, the prompt fission neutron spectrum N(E) and the average prompt neutron multiplicity bar v p . Early representations of the two observables are presented and their deficiencies are discussed. This is followed by summaries and examples of recent theoretical models for the calculation of these quantities. Emphasis is placed upon the predictability and accuracy of the new models. In particular, the dependencies of N(E) and bar v p upon the fissioning nucleus and its excitation energy are treated. Recent work in the calculation of the prompt fission neutron spectrum matrix N(E,E n ), where E n is the energy of the neutron inducing fission, is then discussed. Concluding remarks address the current status of our ability to calculate these observables with confidence, the direction of future theoretical efforts, and limititations to current and future calculations. Finally, recommendations are presented as to which model should be used currently and which model should be pursued in future efforts
International Nuclear Information System (INIS)
Arutunjan, R.V.; Bolshov, L.A.; Vitukov, V.V.; Goloviznin, V.M.; Dykhne, A.M.; Kiselev, V.P.; Klementova, S.V.; Krayushkin, I.E.; Moskovchenko, A.V.; Pismennii, V.D.; Popkov, A.G.; Chernov, S.Y.; Chudanov, V.V.; Khoruzhii, O.V.; Yudin, A.I.
1990-01-01
Migration of fuel fragments and core fission products during severe accidents on nuclear plants is studied analytically and numerically. The problems of heat transfer and migration of volume heat sources in construction materials and underlying soils are considered
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...
Empathy and child neglect: a theoretical model.
De Paul, Joaquín; Guibert, María
2008-11-01
To present an explanatory theory-based model of child neglect. This model does not address neglectful behaviors of parents with mental retardation, alcohol or drug abuse, or severe mental health problems. In this model parental behavior aimed to satisfy a child's need is considered a helping behavior and, as a consequence, child neglect is considered as a specific type of non-helping behavior. The central hypothesis of the theoretical model presented here suggests that neglectful parents cannot develop the helping response set to care for their children because the observation of a child's signal of need does not lead to the experience of emotions that motivate helping or because the parents experience these emotions, but specific cognitions modify the motivation to help. The present theoretical model suggests that different typologies of neglectful parents could be developed based on different reasons that parents might not to experience emotions that motivate helping behaviors. The model can be helpful to promote new empirical studies about the etiology of different groups of neglectful families.
The N2HDM under theoretical and experimental scrutiny
International Nuclear Information System (INIS)
Mühlleitner, Margarete; Sampaio, Marco O.P.; Santos, Rui; Wittbrodt, Jonas
2017-01-01
The N2HDM is based on the CP-conserving 2HDM extended by a real scalar singlet field. Its enlarged parameter space and its fewer symmetry conditions as compared to supersymmetric models allow for an interesting phenomenology compatible with current experimental constraints, while adding to the 2HDM sector the possibility of Higgs-to-Higgs decays with three different Higgs bosons. In this paper the N2HDM is subjected to detailed scrutiny. Regarding the theoretical constraints we implement tests of tree-level perturbativity and vacuum stability. Moreover, we present, for the first time, a thorough analysis of the global minimum of the N2HDM. The model and the theoretical constraints have been implemented in ScannerS, and we provide N2HDECAY, a code based on HDECAY, for the computation of the N2HDM branching ratios and total widths including the state-of-the-art higher order QCD corrections and off-shell decays. We then perform an extensive parameter scan in the N2HDM parameter space, with all theoretical and experimental constraints applied, and analyse its allowed regions. We find that large singlet admixtures are still compatible with the Higgs data and investigate which observables will allow to restrict the singlet nature most effectively in the next runs of the LHC. Similarly to the 2HDM, the N2HDM exhibits a wrong-sign parameter regime, which will be constrained by future Higgs precision measurements.
The N2HDM under theoretical and experimental scrutiny
Energy Technology Data Exchange (ETDEWEB)
Mühlleitner, Margarete [Institute for Theoretical Physics, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany); Sampaio, Marco O.P. [Departamento de Física, Universidade de Aveiro and CIDMA, Campus de Santiago, 3810-183 Aveiro (Portugal); Santos, Rui [ISEL - Instituto Superior de Engenharia de Lisboa, Instituto Politécnico de Lisboa, 1959-007 Lisboa (Portugal); Centro de Física Teórica e Computacional, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Edifício C8, 1749-016 Lisboa (Portugal); Wittbrodt, Jonas [Institute for Theoretical Physics, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany); Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, D-22607 Hamburg (Germany)
2017-03-17
The N2HDM is based on the CP-conserving 2HDM extended by a real scalar singlet field. Its enlarged parameter space and its fewer symmetry conditions as compared to supersymmetric models allow for an interesting phenomenology compatible with current experimental constraints, while adding to the 2HDM sector the possibility of Higgs-to-Higgs decays with three different Higgs bosons. In this paper the N2HDM is subjected to detailed scrutiny. Regarding the theoretical constraints we implement tests of tree-level perturbativity and vacuum stability. Moreover, we present, for the first time, a thorough analysis of the global minimum of the N2HDM. The model and the theoretical constraints have been implemented in ScannerS, and we provide N2HDECAY, a code based on HDECAY, for the computation of the N2HDM branching ratios and total widths including the state-of-the-art higher order QCD corrections and off-shell decays. We then perform an extensive parameter scan in the N2HDM parameter space, with all theoretical and experimental constraints applied, and analyse its allowed regions. We find that large singlet admixtures are still compatible with the Higgs data and investigate which observables will allow to restrict the singlet nature most effectively in the next runs of the LHC. Similarly to the 2HDM, the N2HDM exhibits a wrong-sign parameter regime, which will be constrained by future Higgs precision measurements.
Surface physics theoretical models and experimental methods
Mamonova, Marina V; Prudnikova, I A
2016-01-01
The demands of production, such as thin films in microelectronics, rely on consideration of factors influencing the interaction of dissimilar materials that make contact with their surfaces. Bond formation between surface layers of dissimilar condensed solids-termed adhesion-depends on the nature of the contacting bodies. Thus, it is necessary to determine the characteristics of adhesion interaction of different materials from both applied and fundamental perspectives of surface phenomena. Given the difficulty in obtaining reliable experimental values of the adhesion strength of coatings, the theoretical approach to determining adhesion characteristics becomes more important. Surface Physics: Theoretical Models and Experimental Methods presents straightforward and efficient approaches and methods developed by the authors that enable the calculation of surface and adhesion characteristics for a wide range of materials: metals, alloys, semiconductors, and complex compounds. The authors compare results from the ...
Directory of Open Access Journals (Sweden)
Jauhar Fajrin
2017-03-01
Full Text Available This paper presents a comparison of theoretical and experimental deflection of a hybrid sandwich panel under four-point bending load. The paper initially presents few basic equations developed under three-point load, followed by development of model under four-point bending load and a comparative analysis between theoretical and experimental results. It was found that the proposed model for predicting the deflection of hybrid sandwich panels provided fair agreement with the experimental values. Most of the sandwich panels showed theoretical deflection values higher than the experimental values, which is desirable in the design. It was also noticed that the introduction of intermediate layer does not contribute much to reduce the deflection of sandwich panel as the main contributor for the total deflection was the shear deformation of the core that mostly determined by the geometric of the samples and the thickness of the core.
A Game Theoretic Model of Thermonuclear Cyberwar
Energy Technology Data Exchange (ETDEWEB)
Soper, Braden C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2017-08-23
In this paper we propose a formal game theoretic model of thermonuclear cyberwar based on ideas found in [1] and [2]. Our intention is that such a game will act as a first step toward building more complete formal models of Cross-Domain Deterrence (CDD). We believe the proposed thermonuclear cyberwar game is an ideal place to start on such an endeavor because the game can be fashioned in a way that is closely related to the classical models of nuclear deterrence [4–6], but with obvious modifications that will help to elucidate the complexities introduced by a second domain. We start with the classical bimatrix nuclear deterrence game based on the game of chicken, but introduce uncertainty via a left-of-launch cyber capability that one or both players may possess.
How faith heals: a theoretical model.
Levin, Jeff
2009-01-01
This paper summarizes theoretical perspectives from psychology supportive of a healing effect of faith. First, faith is defined as a congruence of belief, trust, and obedience in relation to God or the divine. Second, evidence for a faith-healing association is presented, empirically and in theory. To exemplify religiously sanctioned affirmation of such a connection, selected passages are cited from the Jewish canon attesting to biblical and rabbinic support for a faith factor in longevity, disease risk, mental health and well-being, disease prevention, and healing. Third, reference to theories of hope, learned optimism, positive illusions, and opening up or disclosure, and to theory and research on psychoneuroimmunology and placebos, demonstrates that contemporary psychology can accommodate a healing power of faith. This is summarized in a typology of five hypothesized mechanisms underlying a faith-healing association, termed behavioral/conative, interpersonal, cognitive, affective, and psychophysiological. Finally, implications are discussed for the rapprochement of religion and medicine.
Understanding the inverse magnetocaloric effect through a simple theoretical model
Energy Technology Data Exchange (ETDEWEB)
Ranke, P.J. von, E-mail: von.ranke@uol.com.b [Instituto de Fisica Armando Dias Tavares-Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier, 524, Rio de Janeiro 20550-013 (Brazil); Alho, B.P.; Nobrega, E.P.; Oliveira, N.A. de [Instituto de Fisica Armando Dias Tavares-Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier, 524, Rio de Janeiro 20550-013 (Brazil)
2009-10-15
We investigated the inverse magnetocaloric effect using a theoretical magnetic model formed by two coupled magnetic lattices to describe a ferrimagnetic system. The influence of the compensation temperature, and the ferrimagnetic-paramagnetic phase transition on the magnetocaloric effect was analyzed. Also, a relation between the area under the magnetocaloric curve and the net magnetic moment of a ferrimagnetic system was established in this work.
Energy Technology Data Exchange (ETDEWEB)
Lucas, G
2006-10-15
The behaviour of silicon carbide under irradiation has been studied using classical and ab initio simulations, focusing on the nano scale elementary processes. First, we have been interested in the calculation of threshold displacement energies, which are difficult to determine both experimentally and theoretically, and also the associated Frenkel pairs. In the framework of this thesis, we have carried out simulations in classical and ab initio molecular dynamics. For the classical approach, two types of potentials have been used: the Tersoff potential, which led to non satisfactory results, and a new one which has been developed during this thesis. This potential allows a better modelling of SiC under irradiation than most of the empirical potentials available for SiC. It is based on the EDIP potential, initially developed to describe defects in silicon, that we have generalized to SiC. For the ab initio approach, the feasibility of the calculations has been validated and average energies of 19 eV for the C and 38 eV for the Si sublattices have been determined, close to the values empirically used in the fusion community. The results obtained with the new potential EDIP are globally in agreement with those values. Finally, the elementary processes involved in the crystal recovery have been studied by calculating the stability of the created Frenkel pairs and determining possible recombination mechanisms with the nudged elastic band method. (author)
Validation of theoretical models through measured pavement response
DEFF Research Database (Denmark)
Ullidtz, Per
1999-01-01
mechanics was quite different from the measured stress, the peak theoretical value being only half of the measured value.On an instrumented pavement structure in the Danish Road Testing Machine, deflections were measured at the surface of the pavement under FWD loading. Different analytical models were...... 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...
International Nuclear Information System (INIS)
Plekhov, O.A.; Saintier, N.; Palin-Luc, T.; Uvarov, S.V.; Naimark, O.B.
2007-01-01
The infrared and structural investigations of energy dissipation processes in metals subjected to cyclic loading have given impetus to the development of a new thermodynamic model with the capability of describing the energy balance under plastic deformation. The model is based on the statistical description of the mesodefect ensemble evolution and its influence on the dissipation ability of the material. Constitutive equations have been formulated for plastic and structural strains, which allow us to describe the stored and dissipated parts of energy under plastic flow. Numerical results indicate that theoretical predictions are in good agreement with the experimentally observed temperature data
Assessing a Theoretical Model on EFL College Students
Chang, Yu-Ping
2011-01-01
This study aimed to (1) integrate relevant language learning models and theories, (2) construct a theoretical model of college students' English learning performance, and (3) assess the model fit between empirically observed data and the theoretical model proposed by the researchers of this study. Subjects of this study were 1,129 Taiwanese EFL…
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
Directory of Open Access Journals (Sweden)
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
Modelling in Accounting. Theoretical and Practical Dimensions
Teresa Szot -Gabryś
2010-01-01
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...
Three General Theoretical Models in Sociology: An Articulated ?(Disunity?
Directory of Open Access Journals (Sweden)
Thaís García-Pereiro
2015-01-01
Full Text Available After merely a brief, comparative reconstruction of the three most general theoretical models underlying contemporary Sociology (atomic, systemic, and fluid it becomes necessary to review the question about the unity or plurality of Sociology, which is the main objective of this paper. To do so, the basic terms of the question are firstly updated by following the hegemonic trends in current studies of science. Secondly the convergences and divergences among the three models discussed are shown. Following some additional discussion, the conclusion is reached that contemporary Sociology is not unitary, and need not be so. It is plural, but its plurality is limited and articulated by those very models. It may therefore be portrayed as integrated and commensurable, to the extent that a partial and unstable (disunity may be said to exist in Sociology, which is not too far off from what happens in the natural sciences.
Physics of human cooperation: experimental evidence and theoretical models
Sánchez, Angel
2018-02-01
In recent years, many physicists have used evolutionary game theory combined with a complex systems perspective in an attempt to understand social phenomena and challenges. Prominent among such phenomena is the issue of the emergence and sustainability of cooperation in a networked world of selfish or self-focused individuals. The vast majority of research done by physicists on these questions is theoretical, and is almost always posed in terms of agent-based models. Unfortunately, more often than not such models ignore a number of facts that are well established experimentally, and are thus rendered irrelevant to actual social applications. I here summarize some of the facts that any realistic model should incorporate and take into account, discuss important aspects underlying the relation between theory and experiments, and discuss future directions for research based on the available experimental knowledge.
Modeling of alkynes: synthesis and theoretical properties
Directory of Open Access Journals (Sweden)
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.
A Theoretical Model for the Prediction of Siphon Breaking Phenomenon
Energy Technology Data Exchange (ETDEWEB)
Bae, Youngmin; Kim, Young-In; Seo, Jae-Kwang; Kim, Keung Koo; Yoon, Juhyeon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2014-10-15
A siphon phenomenon or siphoning often refers to the movement of liquid from a higher elevation to a lower one through a tube in an inverted U shape (whose top is typically located above the liquid surface) under the action of gravity, and has been used in a variety of reallife applications such as a toilet bowl and a Greedy cup. However, liquid drainage due to siphoning sometimes needs to be prevented. For example, a siphon breaker, which is designed to limit the siphon effect by allowing the gas entrainment into a siphon line, is installed in order to maintain the pool water level above the reactor core when a loss of coolant accident (LOCA) occurs in an open-pool type research reactor. In this paper, we develop a theoretical model to predict the siphon breaking phenomenon. In this paper, a theoretical model to predict the siphon breaking phenomenon is developed. It is shown that the present model predicts well the fundamental features of the siphon breaking phenomenon and undershooting height.
POSITIVE LEADERSHIP MODELS: THEORETICAL FRAMEWORK AND RESEARCH
Directory of Open Access Journals (Sweden)
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.
K. Sridhar Moorthy's Theoretical Modelling in Marketing - A Review ...
African Journals Online (AJOL)
Modelling has become a visible tool in many disciplines including marketing and several marketing models have been constructed. These models serve their pedagogical and practical purposes in some cases. However, among the marketing models so often cited is Moorthy‟s Theoretical Modelling in Marketing.
Theoretical study on optical model potential
International Nuclear Information System (INIS)
Lim Hung Gi.
1984-08-01
The optical model potential of non-local effect on the rounded edge of the potential is derived. On the basis of this potential the functional form of the optical model potential, the energy dependence and relationship of its parameters, and the dependency of the values of the parameters on energy change are shown in this paper. (author)
EUDIOMETRIC THEORETIC-APPROACH TO MODELLING THE ...
African Journals Online (AJOL)
The mathematical physics underlying the adsorption and subsequent desorption of dissolved oxygen (DO) in a water body subject to effluent loading had ... of hat matrix and bootstrapping techniques to study the phenomenon of chemical adsorption and desorption of DO at molecular level in a polluted waterbody has not ...
Hypermedia as an experiential learning tool: a theoretical model
Jose Miguel Baptista Nunes; Susan P. Fowell
1996-01-01
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 learni...
Theoretical Models of Neutrino Mixing Recent Developments
Altarelli, Guido
2009-01-01
The data on neutrino mixing are at present compatible with Tri-Bimaximal (TB) mixing. If one takes this indication seriously then the models that lead to TB mixing in first approximation are particularly interesting and A4 models are prominent in this list. However, the agreement of TB mixing with the data could still be an accident. We discuss a recent model based on S4 where Bimaximal mixing is instead valid at leading order and the large corrections needed to reproduce the data arise from the diagonalization of charged leptons. The value of $\\theta_{13}$ could distinguish between the two alternatives.
Theoretical Analysis of a Modified Continuum Model
Ge, Hong-Xia; Wu, Shu-Zhen; Cheng, Rong-Jun; Lo, Siu-ming
2011-09-01
Based on the optimal velocity (OV) model, a new car-following model for traffic flow with the consideration of the driver's forecast effect (DFE) was proposed by Tang et al., which can be used to describe some complex traffic phenomena better. Using an asymptotic approximation between the headway and density, we obtain a new macro continuum version of the car-following model with the DFE. The linear stability theory is applied to derive the neutral stability condition. The Korteweg—de Vries equation near the neutral stability line is given by nonlinear analysis and the corresponding solution for the traffic density wave is derived.
[Nursing practice based on theoretical models: a qualitative study of nurses' perception].
Amaducci, Giovanna; Iemmi, Marina; Prandi, Marzia; Saffioti, Angelina; Carpanoni, Marika; Mecugni, Daniela
2013-01-01
Many faculty argue that theory and theorizing are closely related to the clinical practice, that the disciplinary knowledge grows, more relevantly, from the specific care context in which it takes place and, moreover, that knowledge does not proceed only by the application of general principles of the grand theories to specific cases. Every nurse, in fact, have a mental model, of what may or may not be aware, that motivate and substantiate every action and choice of career. The study describes what the nursing theoretical model is; the mental model and the tacit knowledge underlying it. It identifies the explicit theoretical model of the professional group that rapresents nursing partecipants, aspects of continuity with the theoretical model proposed by this degree course in Nursing.. Methods Four focus groups were made which were attended by a total of 22 nurses, rapresentatives of almost every Unit of Reggio Emilia Hospital's. We argue that the theoretical nursing model of each professional group is the result of tacit knowledge, which help to define the personal mental model, and the theoretical model, which explicitly underlying theoretical content learned applied consciously and reverted to / from nursing practice. Reasoning on the use of theory in practice has allowed us to give visibility to a theoretical model explicitly nursing authentically oriented to the needs of the person, in all its complexity in specific contexts.
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.
From theoretical model to practical use:
DEFF Research Database (Denmark)
Bjørk, Ida Torunn; Lomborg, Kirsten; Nielsen, Carsten Munch
2013-01-01
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...... involving both the creation and application of knowledge in several phases. The case presented in this paper is the translation of the Model of Practical Skill Performance into education and practice. Advantages and problems with the use of this model and its adaptation and tailoring to local contexts...... 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...
Theoretical modelling of carbon deposition processes
International Nuclear Information System (INIS)
Marsh, G.R.; Norfolk, D.J.; Skinner, R.F.
1985-01-01
Work based on capsule experiments in the BNL Gamma Facility, aimed at elucidating the chemistry involved in the formation of carbonaceous deposit on CAGR fuel pin surfaces is described. Using a data-base derived from capsule experiments together with literature values for the kinetics of the fundamental reactions, a chemical model of the gas-phase processes has been developed. This model successfully reproduces the capsule results, whilst preliminary application to the WAGR coolant circuit indicates the likely concentration profiles of various radical species within the fuel channels. (author)
SOME THEORETICAL MODELS EXPLAINING ADVERTISING EFFECTS
Directory of Open Access Journals (Sweden)
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.
Theoretical Modelling of Intercultural Communication Process
Directory of Open Access Journals (Sweden)
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.
A Theoretical Model for Metal Corrosion Degradation
Directory of Open Access Journals (Sweden)
David V. Svintradze
2010-01-01
Full Text Available Many aluminum and stainless steel alloys contain thin oxide layers on the metal surface which greatly reduce the corrosion rate. Pitting corrosion, a result of localized breakdown of such films, results in accelerated dissolution of the underlying metal through pits. Many researchers have studied pitting corrosion for several decades and the exact governing equation for corrosion pit degradation has not been obtained. In this study, the governing equation for corrosion degradation due to pitting corrosion behavior was derived from solid-state physics and some solutions and simulations are presented and discussed.
K. Sridhar Moorthy's Theoretical Modelling in Marketing - A Review
African Journals Online (AJOL)
Toshiba
cases. However, among the marketing models so often cited is. Moorthy‟s Theoretical Modelling in Marketing. This model is important, and hence this review once more, in that it offers a starting point, and in some cases the finishing line, for those who want to tread the pedestrian of modelling in marketing. But this is not the ...
K. Sridhar Moorthy's Theoretical Modelling in Marketing - A Review
African Journals Online (AJOL)
Toshiba
/afrrev.v8i1.15. K. Sridhar Moorthy's Theoretical Modelling in. Marketing - A Review. Okoye, Ikechukwu-Maria Nnamdi Hyacinth. Head, Micro Enterprise Development/Training. University of Nigeria Nsukka Centre for Entrepreneurship and.
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...
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
2012-01-01
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...
Theoretical evaluation of radon emanation under a variety of conditions
International Nuclear Information System (INIS)
Edwards, J.C.; Bates, R.C.
1980-01-01
A cylindrical coordinate mathematical model to calculate 222 Rn flux and movement was developed considering 222 Rn production, decay, and diffusion in a multilayered, porous, permeable matrix. Air movement, transporting radon through the media, satisfies Darcy's law and is influenced by the air (barometric) pressure applied at the surface. Two zones of porous material have been defined, one with a 222 Rn production term (the uranium ore zone) and the other without this term to simulate shotcrete or concrete ground support. A provision is made to evaluate the effect of a pinhole in an otherwise impermeable sealant. Comparisons are made between field measurements and predicted values. Specific examples are given of 222 Rn flux from a finite ore-body model versus steady and periodic changes in barometric pressure. Also examined are 222 Rn losses through pinholes for cases of linearly varying and static barometric pressures. The results suggest factors to consider in uranium mine radon control. For example, pinholes are not a serious problem since it appears that several thousand, 2 mm diameter pinholes per square meter are required to cause a significant loss of a barrier coating's effectiveness. (author)
Category-theoretic models of linear Abadi & Plotkin Logic
DEFF Research Database (Denmark)
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 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 postulation of PLC channel model
Directory of Open Access Journals (Sweden)
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.
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.
An Experimental and Theoretical Investigation of a Micromirror Under Mixed-Frequency Excitation
Ilyas, Saad
2015-01-12
We present an experimental and theoretical investigation of a micromachined mirror under a mixed-frequency signal composed of two harmonic ac sources. The micromirror is made of polyimide as the main structural layer. The experimental and theoretical dynamics are explored via frequency sweeps in the desired neighborhoods. One frequency is fixed while the other frequency is swept through a wide range to study the dynamic responses. To simulate the behavior of the micromirror, it is modeled as a single degree of freedom system, where the parameters of the model are extracted experimentally. A good agreement is reported among the simulation results and the experimental data. These responses are studied under different frequencies and input voltages. The results show interesting dynamics, where the system exhibits primary resonance and combination resonances of additive and subtractive type. The mixed excitation is demonstrated as a way to increase the bandwidth of the resonator near primary resonance, which can be promising for resonant sensing applications in the effort to increase the signal-noise ratio over extended frequency range.
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 modelling of actinide spectra in solution
International Nuclear Information System (INIS)
Danilo, Cecile
2009-01-01
The framework of this PhD is the interpretation of Nuclear Magnetic Relaxation Dispersion experiments performed on solvated U 4+ , NpO 2 + and PuO 2 2+ , which all have a f 2 configuration. Unexpectedly the two actinyl ions have a much higher relaxivity than U 4+ ,. One possible explanation is that the electronic relaxation rate is faster for Uranium(IV) than for the actinyl ions. We address this problem by exploring the electronic spectrum of the three compounds in gas phase and in solution with a two-step SOCI (Spin-Orbit Configuration-Interaction) method. The influence of electron correlation (treated in the first step) and spin-orbit relaxation effects (considered in the second step) has been discussed thoroughly. Solvent effects have been investigated as well. Another issue that has been questioned is the accuracy of Density Functional Theory for the study of actinide species. This matter has been discussed by comparing its performance to wave-function based correlated methods. The chemical problem chosen was the water exchange in [UO 2 2+ (H 2 O) 5 ]. We looked at the associative and at the dissociative mechanisms using a model with one additional water in the second hydration sphere. The last part of the thesis dealt with the spectroscopy of coordinated Uranyl(V). Absorption spectrum of Uranyl(V) with various ligands has been recorded. The first sharp absorption bands in the Near-Infrared region were assigned to the Uranium centered 5f-5f transitions, but uncertainties remained for the assignment of transitions observed in the Visible region. We computed the spectra of naked UO 2 + and [UO 2 (CO 3 ) 3 ] 5- to elucidate the spectral changes induced by the carbonate ligands. (author) [fr
Modeling theoretical uncertainties in phenomenological analyses for particle physics
Energy Technology Data Exchange (ETDEWEB)
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.)
A Simple theoretical model for 63Ni betavoltaic battery
International Nuclear Information System (INIS)
ZUO, Guoping; ZHOU, Jianliang; KE, Guotu
2013-01-01
A numerical simulation of the energy deposition distribution in semiconductors is performed for 63 Ni beta particles. Results show that the energy deposition distribution exhibits an approximate exponential decay law. A simple theoretical model is developed for 63 Ni betavoltaic battery based on the distribution characteristics. The correctness of the model is validated by two literature experiments. Results show that the theoretical short-circuit current agrees well with the experimental results, and the open-circuit voltage deviates from the experimental results in terms of the influence of the PN junction defects and the simplification of the source. The theoretical model can be applied to 63 Ni and 147 Pm betavoltaic batteries. - Highlights: • The energy deposition distribution is found following an approximate exponential decay law when beta particles emitted from 63 Ni pass through a semiconductor. • A simple theoretical model for 63 Ni betavoltaic battery is constructed based on the exponential decay law. • Theoretical model can be applied to the betavoltaic batteries which radioactive source has a similar energy spectrum with 63 Ni, such as 147 Pm
International Nuclear Information System (INIS)
Ra, Ki Yong
1992-02-01
For the purpose of analyzing the nuclear energy policy under uncertainties, new utility theoretic approaches were applied. The main discoveries of new utility theories are that, firstly, the consequences can affect the perceived probabilities, secondly, the utilities are not fixed but can change, and finally, utilities and probabilities thus should be combined dependently to determine the overall worth of risky option. These conclusions were applied to develop the modified expected utility model and to establish the probabilistic nuclear safety criterion. The modified expected utility model was developed in order to resolve the inconsistencies between the expected utility model and the actual decision behaviors. Based on information theory and Bayesian inference, the modified probabilities were obtained as the stated probabilities times substitutional factors. The model theoretically predicts that the extreme value outcomes are perceived as to be more likely to occur than medium value outcomes. This prediction is consistent with the first finding of new utility theories that the consequences can after the perceived probabilities. And further with this theoretical prediction, the decision behavior of buying lottery ticket, of paying for insurance and of nuclear catastrophic risk aversion can well be explained. Through the numerical application, it is shown that the developed model can well explain the common consequence effect, common ratio effect and reflection effect. The probabilistic nuclear safety criterion for core melt frequency was established: Firstly, the distribution of the public's safety goal (DPSG) was proposed for representing the public's group preference under risk. Secondly, a new probabilistic safety criterion (PSC) was established, in which the DPSG was used as a benchmark for evaluating the results of probabilistic safety assessment. Thirdly, a log-normal distribution was proposed as the appropriate DPSG for core melt frequency using the
Test of theoretical models for ultrafast heterogeneous electron ...
Indian Academy of Sciences (India)
Administrator
with the predictions of different theoretical models for light-induced ultrafast heterogeneous electron transfer (HET). ... theory model based on molecular dynamics simulations for the vibrational modes were also considered. Based on the known vibrational .... Pseudo 3D map of a 2PPE measurement with. Pe' achored via the ...
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.
Circumplex model of marital and family systems: VI. Theoretical update.
Olson, D H; Russell, C S; Sprenkle, D H
1983-03-01
This paper updates the theoretical work on the Circumplex Model and provides revised and new hypotheses. Similarities and contrasts to the Beavers Systems Model are made along with comments regarding Beavers and Voeller's critique. FACES II, a newly revised assessment tool, provides both "perceived" and "ideal" family assessment that is useful empirically and clinically.
A theoretical model for predicting neutron fluxes for cyclic Neutron ...
African Journals Online (AJOL)
A theoretical model has been developed for prediction of thermal neutron fluxes required for cyclic irradiations of a sample to obtain the same activity previously used for the detection of any radionuclide of interest. The model is suitable for radiotracer production or for long-lived neutron activation products where the ...
Culture and Developmental Trajectories: A Discussion on Contemporary Theoretical Models
de Carvalho, Rafael Vera Cruz; Seidl-de-Moura, Maria Lucia; Martins, Gabriela Dal Forno; Vieira, Mauro Luís
2014-01-01
This paper aims to describe, compare and discuss the theoretical models proposed by Patricia Greenfield, Çigdem Kagitçibasi and Heidi Keller. Their models have the common goal of understanding the developmental trajectories of self based on dimensions of autonomy and relatedness that are structured according to specific cultural and environmental…
Desublimation process: verification and applications of a theoretical model
International Nuclear Information System (INIS)
Eby, R.S.
1979-01-01
A theoretical model simulating the simultaneous heat and mass transfer which takes place during the desublimation of a gas to a solid is presented. Desublimer column loading profiles to experimentally verify the model were obtained using a gamma scintillation technique. The data indicate that, if the physical parameters of the desublimed frost material are known, the model can accurately predict the desublimation phenomenon. The usefulness of the model in different engineering applications is also addressed
Theoretical Foundations of the New Industrialization of the Mining Region under Globalization
Directory of Open Access Journals (Sweden)
Kusurgasheva Ludmila
2017-01-01
Full Text Available This study is intended to establish theoretical foundations of the new industrialization of the mining region under the globalization. The urgency of the problem is due to a significant de-industrialization of many branches of the Russian economy as a result of the neoliberal macroeconomic paradigm in the years of radical market reforms. As a result, a number of Russian regions has formed the structure of industrial production, which is characteristic mainly for the countries of the raw materials periphery. The authors see the new industrialization (neo-industrialization as a strategic tool for solving the problem. The trend that has formed in the Russian regional policy to transfer the responsibility for the economy modernization to the regional level has attached the special importance to regional studies. Exhaustion of predominantly raw-materials export model of economic growth has put Kuzbass, the mining region in Western Siberia, in the most difficult situation due to its tight dependence on the state of the world market of energy resources. This article presents a theoretical justification of the need, feasibility and advisability of neo-industrialization for the mining region in the conditions of globalization.
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…
Workshop IV – Cosmology-theoretical models/alternative scenarios ...
Indian Academy of Sciences (India)
Workshop IV – Cosmology-theoretical models/alternative scenarios: A report. ASIT BANERJEE. ½ and REZA TAVAKOL. 2. ½. Department of Physics, Jadavpur University, Calcutta 700 032, India. ¾. Astronomy Unit, School of Mathematical Sciences, Queen Mary and Westfield College, Mile End. Road, London E1 4NS, UK.
The development of a theoretical model to investigate factors
African Journals Online (AJOL)
user
ISSN 0378-5254 Journal of Family Ecology and Consumer Sciences, Vol 41, 2013. The development of a theoretical model to investigate factors associated with environmentally significant choice behaviour in the South ..... attitudes toward the behaviour, social pressure or subjective norms surrounding the behaviour.
Theoretical modeling and experimental analyses of laminated wood composite poles
Cheng Piao; Todd F. Shupe; Vijaya Gopu; Chung Y. Hse
2005-01-01
Wood laminated composite poles consist of trapezoid-shaped wood strips bonded with synthetic resin. The thick-walled hollow poles had adequate strength and stiffness properties and were a promising substitute for solid wood poles. It was necessary to develop theoretical models to facilitate the manufacture and future installation and maintenance of this novel...
Theoretical model analysis of molecular orientations in liquid protein ...
African Journals Online (AJOL)
In this study, some theoretical model functions have been used to explain the molecular behaviour of four different types of proteins; human haemoglobin, Insulin, egg-white lysozyme and β - globulin molecules in solution. The results of the computational fitting procedures showed that the dielectric dispersion of the protein ...
Theoretical Model of Engagement in the Context of Brand Communities
Directory of Open Access Journals (Sweden)
Flávia D\\u2019albergaria Freitas
2017-01-01
Full Text Available This essay proposes to refine the concept of consumer engagement in the context of brand communities. A comprehensive review of studies addressing the phenomenon of brand community was made. This paper follows the tradition of Marketing Research and Consumer Behavior, more specifically the perspective of cognitive psychology. The main theoretical foundation of the study is the Social Identity Theory (SIT, also incorporating relevant contributions from the perspective of Consumer Culture Theory (CCT. Therefore, this study contributes to the progress of research on the phenomenon of engagement in brand communities, proposing a theoretical model that relates engagement with its antecedents factors and reflective dimensions.
A comparison of graph-theoretic DNA hybridization models
Brijder, Robert; Gillis Joris; Van den Bussche, Jan
2012-01-01
We show that the graph-theoretic DNA hybridization models of pot tiles [4, 5] and of sticker complexes [3, 2] are equivalent. This allows one to carry over known results from one model to the other. In addition, we introduce the concept of “greedy” hybridization and compare it to “regular” hybridization. DNA hybridization; multiset-based graph grammars; self-assembly; database theory
Management Innovation – Designing And Testing A Theoretical Model
Directory of Open Access Journals (Sweden)
Bezdrob Muamer
2015-04-01
Full Text Available Management innovation – the introduction of management processes, structures and practices that are new to companies, is crucial to business success. Based on the existing literature on management innovation and a rigorous theoretical approach to model design and development, a theoretical model of management innovation that is applicable to immature and underdeveloped markets was designed. Using this model, the study shows that the context in which companies operate, as well as companies’ management background (proficiency, are directly and positively related to management innovation. The main implication of the research is that the existing management innovation theory is applicable to market conditions in the Federation of Bosnia and Herzegovina with only slight adaptation. Furthermore, this research provides important insights about the factors that affect the companies’ readiness to introduce innovative management structures, processes and practices.
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.
Wang, Yuexing; Yao, Yao
2017-10-01
In this work, analysis of electromigration-induced void morphological evolution in solder interconnects is performed based on mass diffusion theory. The analysis is conducted for three typical experimentally observed void shapes: circular, ellipse, and cardioid. Void morphological evolution is governed by the competition between the electric field and surface capillary force. In the developed model, both the electric field and capillary force on the void's surface are solved analytically. Based on the mass conversation principle, the normal velocity on the void surface during diffusion is obtained. The void morphological evolution behavior is investigated, and a physical model is developed to predict void collapse to a crack or to split into sub-voids under electric current. It is noted that when the electric current is being applied from the horizontal direction, a circular void may either move stably along the electric current direction or collapse to a finger shape, depending on the relative magnitude of the electric current and surface capillary force. However, the elliptical-shaped void will elongate along the electric current direction and finally collapse to the finger shape. On the other hand, the cardioid-shaped void could bifurcate into two sub-voids when the electric current reaches a critical value. The theoretical predictions agree well with the experimental observations.
Continuum damage modeling through theoretical and experimental pressure limit formulas
Directory of Open Access Journals (Sweden)
Fatima Majid
2018-01-01
Full Text Available In this paper, we developed a mathematical modeling to represent the damage of thermoplastic pipes. On the one hand, we adapted the theories of the rupture pressure to fit the High Density Polyethylene (HDPE case. Indeed, the theories for calculating the rupture pressure are multiple, designed originally for steels and alloys. For polymer materials, we have found that these theories can be adapted using a coefficient related to the nature of the studied material. The HDPE is characterized by two important values of pressure, deduced from the ductile form of the internal pressures evolution until burst. For this reason, we have designed an alpha coefficient taking into account these two pressures and giving a good approximation of the evolution of the experimental burst pressures through the theoretically corrected ones, using Faupel㒒s pressure formula. Then, we can deduce the evolution of the theoretical damage using the calculated pressures. On the other hand, two other mathematical models were undertaken. The first one has given rise to an adaptive model referring to an expression of the pressure as a function of the life fraction, the characteristic pressures and the critical life fraction. The second model represents a continuum damage model incorporating the pressure equations as a function of the life fraction and based on the burst pressure�s static damage model. These models represent important tools for industrials to assess the failure of thermoplastic pipes and proceed quick checks
A Theoretical Model for Meaning Construction through Constructivist Concept Learning
DEFF Research Database (Denmark)
Badie, Farshad
The central focus of this Ph.D. research is on ‘Logic and Cognition’ and, more specifically, this research covers the quintuple (Logic and Logical Philosophy, Philosophy of Education, Educational Psychology, Cognitive Science, Computer Science). The most significant contributions of this Ph...... of ‘learning’, ‘mentoring’, and ‘knowledge’ within learning and knowledge acquisition systems. Constructivism as an epistemology and as a model of knowing and, respectively as a theoretical model of learning builds up the central framework of this research....
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.
Comparison of two mean-field based theoretical analysis methods for SIS model
Zhang, Jiaquan; Lu, Dan; Yang, Shunkun
2017-11-01
Epidemic spreading has been intensively studied in SIS epidemic model. Although the mean-field theory of SIS model has been widely used in the research, there is a lack of comparative results between different theoretical calculations, and the differences between them should be systematically explained. In this paper, we have compared different theoretical solutions for mean-field theory and explained the underlying reason. We first describe the differences between different equations for mean-field theory in different networks. The results show that the difference between mean-field reaction equations is due to the different probability consideration for the infection process. This finding will help us to design better theoretical solutions for epidemic models.
Application of a theoretical model to evaluate COPD disease management
2010-01-01
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 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. PMID:20346135
Application of a theoretical model to evaluate COPD disease management
Directory of Open Access Journals (Sweden)
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.
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 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.
Theoretical Modeling of Rock Breakage by Hydraulic and Mechanical Tool
Directory of Open Access Journals (Sweden)
Hongxiang Jiang
2014-01-01
Full Text Available Rock breakage by coupled mechanical and hydraulic action has been developed over the past several decades, but theoretical study on rock fragmentation by mechanical tool with water pressure assistance was still lacking. The theoretical model of rock breakage by mechanical tool was developed based on the rock fracture mechanics and the solution of Boussinesq’s problem, and it could explain the process of rock fragmentation as well as predicating the peak reacting force. The theoretical model of rock breakage by coupled mechanical and hydraulic action was developed according to the superposition principle of intensity factors at the crack tip, and the reacting force of mechanical tool assisted by hydraulic action could be reduced obviously if the crack with a critical length could be produced by mechanical or hydraulic impact. The experimental results indicated that the peak reacting force could be reduced about 15% assisted by medium water pressure, and quick reduction of reacting force after peak value decreased the specific energy consumption of rock fragmentation by mechanical tool. The crack formation by mechanical or hydraulic impact was the prerequisite to improvement of the ability of combined breakage.
Theoretical research of helium pulsating heat pipe under steady state conditions
International Nuclear Information System (INIS)
Xu, D; Liu, H M; Li, L F; Huang, R J; Wang, W
2015-01-01
As a new-type heat pipe, pulsating heat pipe (PHP) has several outstanding features, such as great heat transport ability, strong adjustability, small size and simple construction. PHP is a complex two-phase flow system associated with many physical subjects and parameters, which utilizes the pressure and temperature changes in volume expansion and contraction during phase changes to excite the pulsation motion of liquid plugs and vapor bubbles in the capillary tube between the evaporator and the condenser. At present time, some experimental investigation of helium PHP have been done. However, theoretical research of helium PHP is rare. In this paper, the physical and mathematical models of operating mechanism for helium PHP under steady state are established based on the conservation of mass, momentum, and energy. Several important parameters are correlated and solved, including the liquid filling ratio, flow velocity, heat power, temperature, etc. Based on the results, the operational driving force and flow resistances of helium PHP are analysed, and the flow and heat transfer is further studied. (paper)
Narayanan, Radhika; Inomata, Kensuke; Gopakumar, Geetha; Sivaraman, Bhalamurugan; Zempo, Yasunari; Hada, Masahiko
2016-01-15
Identification of methyl acetate in the interstellar medium (ISM) and its spectroscopic studies have prompted us to investigate the structure of crystalline methyl acetate using numerical calculations. Here, we present a theoretical study of the structure of crystalline methyl acetate and its isotopologues and compare the calculated infrared (IR) spectra with the available experimental data. The optimized structure and vibrational properties were calculated using SIESTA software at 0 K. In the optimization process, the Perdew-Burke-Ernzerhof functional and conjugate gradient methods were used with double zeta polarization basis functions. After optimization of the periodic structure, the vibrational frequencies and normal modes were calculated within the harmonic approximation. Using the calculated results, we refine the mode assignments of experimental work on crystalline methyl acetate and determine the low frequency modes (below 650 cm(-1)). To investigate the accuracy of the pseudopotential and confirm the IR frequencies, we performed molecular calculations using a periodic model of methyl acetate and its isotopologues using SIESTA and compared them with results obtained from Gaussian 09 (all electron method) calculations. Finally, we assigned the vibrational modes of crystalline CD3-COO-CH3 and CH3-COO-CD3, for which experimental data are not available in the crystalline phase under ISM conditions. For all of the calculation methods, the IR vibrational modes of molecular and crystalline methyl acetate and its isotopologues were in good agreement with the available experimental data and predict the unavailable values. Copyright © 2015 Elsevier B.V. All rights reserved.
Chemical model reduction under uncertainty
Najm, Habib
2016-01-05
We outline a strategy for chemical kinetic model reduction under uncertainty. We present highlights of our existing deterministic model reduction strategy, and describe the extension of the formulation to include parametric uncertainty in the detailed mechanism. We discuss the utility of this construction, as applied to hydrocarbon fuel-air kinetics, and the associated use of uncertainty-aware measures of error between predictions from detailed and simplified models.
Theoretical models for Mars and their seismic properties
Okal, E. A.; Anderson, D. L.
1978-01-01
Theoretical seismic properties of the planet Mars are investigated on the basis of the various models which have been proposed for the internal composition of the planet. The latest interpretation of gravity-field data, assuming a lower value of the moment of inertia, would require a less dense mantle and a larger core than previous models. If Mars is chondritic in composition, the most reasonable models are an incompletely differentiated H-chondrite or a mixture of H-chondrites and carbonaceous chondrites. Seismic profiles, travel times, and free oscillation periods are computed for various models, with the aim of establishing which seismic data is crucial for deciding among the alternatives. A detailed discussion is given of the seismic properties which could - in principle - help answer the questions of whether Mars' core is liquid or solid and whether Mars has a partially molten asthenosphere in its upper mantle.
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
A Game-Theoretic Model for Distributed Programming by Contract
DEFF Research Database (Denmark)
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....
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.
An Emerging Theoretical Model of Music Therapy Student Development.
Dvorak, Abbey L; Hernandez-Ruiz, Eugenia; Jang, Sekyung; Kim, Borin; Joseph, Megan; Wells, Kori E
2017-07-01
Music therapy students negotiate a complex relationship with music and its use in clinical work throughout their education and training. This distinct, pervasive, and evolving relationship suggests a developmental process unique to music therapy. The purpose of this grounded theory study was to create a theoretical model of music therapy students' developmental process, beginning with a study within one large Midwestern university. Participants (N = 15) were music therapy students who completed one 60-minute intensive interview, followed by a 20-minute member check meeting. Recorded interviews were transcribed, analyzed, and coded using open and axial coding. The theoretical model that emerged was a six-step sequential developmental progression that included the following themes: (a) Personal Connection, (b) Turning Point, (c) Adjusting Relationship with Music, (d) Growth and Development, (e) Evolution, and (f) Empowerment. The first three steps are linear; development continues in a cyclical process among the last three steps. As the cycle continues, music therapy students continue to grow and develop their skills, leading to increased empowerment, and more specifically, increased self-efficacy and competence. Further exploration of the model is needed to inform educators' and other key stakeholders' understanding of student needs and concerns as they progress through music therapy degree programs. © the American Music Therapy Association 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com
Theoretical analysis of moiré fringe multiplication under a scanning electron microscope
International Nuclear Information System (INIS)
Li, Yanjie; Xie, Huimin; Chen, Pengwan; Zhang, Qingming
2011-01-01
In this study, theoretical analysis and experimental verification of fringe multiplication under a scanning electron microscope (SEM) are presented. Fringe multiplication can be realized by enhancing the magnification or the number of scanning lines under the SEM. A universal expression of the pitch of moiré fringes is deduced. To apply this method to deformation measurement, the calculation formulas of strain and displacement are derived. Compared to natural moiré, the displacement sensitivity is increased by fringe multiplication while the strain sensitivity may be retained or enhanced depending on the number of scanning lines used. The moiré patterns are formed by the interference of a 2000 lines mm −1 grating with the scanning lines of SEM, and the measured parameters of moiré fringes from experimental results agree well with theoretical analysis
The theoretical aspects of UrQMD & AMPT models
Energy Technology Data Exchange (ETDEWEB)
Saini, Abhilasha, E-mail: kashvini.abhi@gmail.com [Research Scholar, Department of Physics, Suresh Gyan vihar University, Jaipur (India); Bhardwaj, Sudhir, E-mail: sudhir.hep@gmail.com [Assistant professor, Govt. College of Engineering & Technology, Bikaner (India)
2016-05-06
The field of high energy physics is very challenging in carrying out theories and experiments to unlock the secrets of heavy ion collisions and still not cracked and solved completely. There are many theoretical queries; some may be due to the inherent causes like the non-perturbative nature of QCD in the strong coupling limit, also due to the multi-particle production and evolution during the heavy ion collisions which increase the complexity of the phenomena. So for the purpose of understanding the phenomena, variety of theories and ideas are developed which are usually implied in the form of Monte-Carlo codes. The UrQMD model and the AMPT model are discussed here in detail. These methods are useful in modeling the nuclear collisions.
Graph theoretical model of a sensorimotor connectome in zebrafish.
Directory of Open Access Journals (Sweden)
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.
Modelling microstructural evolution under irradiation
International Nuclear Information System (INIS)
Tikare, V.
2015-01-01
Microstructural evolution of materials under irradiation is characterised by some unique features that are not typically present in other application environments. While much understanding has been achieved by experimental studies, the ability to model this microstructural evolution for complex materials states and environmental conditions not only enhances understanding, it also enables prediction of materials behaviour under conditions that are difficult to duplicate experimentally. Furthermore, reliable models enable designing materials for improved engineering performance for their respective applications. Thus, development and application of mesoscale microstructural model are important for advancing nuclear materials technologies. In this chapter, the application of the Potts model to nuclear materials will be reviewed and demonstrated, as an example of microstructural evolution processes. (author)
Delayed hydride cracking: theoretical model testing to predict cracking velocity
International Nuclear Information System (INIS)
Mieza, Juan I.; Vigna, Gustavo L.; Domizzi, Gladys
2009-01-01
Pressure tubes from Candu nuclear reactors as any other component manufactured with Zr alloys are prone to delayed hydride cracking. That is why it is important to be able to predict the cracking velocity during the component lifetime from parameters easy to be measured, such as: hydrogen concentration, mechanical and microstructural properties. Two of the theoretical models reported in literature to calculate the DHC velocity were chosen and combined, and using the appropriate variables allowed a comparison with experimental results of samples from Zr-2.5 Nb tubes with different mechanical and structural properties. In addition, velocities measured by other authors in irradiated materials could be reproduced using the model described above. (author)
Theoretical model of intravascular paramagnetic tracers effect on tissue relaxation
DEFF Research Database (Denmark)
Kjølby, Birgitte Fuglsang; Østergaard, Leif; Kiselev, Valerij G
2006-01-01
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...... into account a number of individual compartments. The signal dephasing is simulated in a semianalytical way by embedding Monte Carlo simulations in the framework of analytical theory. This approach yields a tool for fast, realistic simulation of the change in the transverse relaxation. The results indicate...... 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...
Dependence of tropical cyclone development on coriolis parameter: A theoretical model
Deng, Liyuan; Li, Tim; Bi, Mingyu; Liu, Jia; Peng, Melinda
2018-03-01
A simple theoretical model was formulated to investigate how tropical cyclone (TC) intensification depends on the Coriolis parameter. The theoretical framework includes a two-layer free atmosphere and an Ekman boundary layer at the bottom. The linkage between the free atmosphere and the boundary layer is through the Ekman pumping vertical velocity in proportion to the vorticity at the top of the boundary layer. The closure of this linear system assumes a simple relationship between the free atmosphere diabatic heating and the boundary layer moisture convergence. Under a set of realistic atmospheric parameter values, the model suggests that the most preferred latitude for TC development is around 5° without considering other factors. The theoretical result is confirmed by high-resolution WRF model simulations in a zero-mean flow and a constant SST environment on an f -plane with different Coriolis parameters. Given an initially balanced weak vortex, the TC-like vortex intensifies most rapidly at the reference latitude of 5°. Thus, the WRF model simulations confirm the f-dependent characteristics of TC intensification rate as suggested by the theoretical model.
Çelik, Kayhan; Kurt, Erol; Uzun, Yunus
2017-07-01
In the present study, experimental and theoretical explorations on the buckling features of a wind energy harvester have been performed. The harvester consists of a piezoelectric layer, which has a certain stiffness and voltage conversion rate. A blade rotates on a shaft carrying a magnet and sweeps the tip of the layer causing a serial buckling effect resulting in energy generation. Since the modeling of the buckling under a magnetic strength includes nonlinear terms over displacements, one requires a detailed study on the characteristics of buckling phenomena. It has been proven that the piezoelectric beam having the magnet at its tip can produce regular and chaotic dynamics for different frequencies (i.e. the rotation speed). In addition, there exist a number of quasi-periodic regions on the parameter space. The overall result indicates that the large area of complicated dynamics requires a detailed study in order to stabilize the position and velocity of the layer tip, thereby a much stabilized energy conversion from mechanical to electrical can be obtained. The present survey on the dynamics of the harvester is a new study and is considered as a two-parameter diagram [i.e. the wind speed (frequency) and magnetic strength]. Mainly, single-, double-, triple- and quadruple-type phase space portraits have been observed and the ripples on the maximal and minimal values of the beam velocity have been observed for certain rotation speeds. These results can be used in order to stabilize the harvester in terms of the reduction of total harmonic distortion in the generated waveform.
Fu, Yuhang; Bai, Lin; Jin, Yong; Cheng, Yi
2017-03-01
Asymmetric droplet breakup under a pressure difference at two outlets of a T-junction is investigated theoretically and numerically in this study. An accurate analysis of the evolution of droplet dynamics during the obstructed breakup process has been conducted. Meanwhile, the lattice Boltzmann method based on color gradient model is employed to simulate the system with the verification of the theoretical results. It is demonstrated that the Zou-He boundary setting at each outlet is advantageous for modifying the pressure drop of the two branches of T-junction. The results reveal that asymmetric breakup of the unequally sized droplets follows two steps, namely, the filling stage and the breakup stage. Then a universal parameter is proposed to describe the asymmetric condition of droplet breakup in T-junction, which plays a key role to characterize the temporal evolution of volume ratio and the droplet length of formed smaller droplets.
Proposal of a theoretical model for the practical nurse
Directory of Open Access Journals (Sweden)
Dolores Abril Sabater
2010-01-01
Full Text Available AIM: To determine which model of nursing is proposed by care professionals and the reason for their choice. METHOD: cross-sectional, descriptive study design. The main variable: Nursing Models and Theories. As secondary variables were collected: age, gender, years of work experience, nursing model of basic training, and course/s related. We used a self-elaborated, anonymous questionnaire, passed between April - May, 2006. Not random sample.RESULTS: 546 nurses were invited, answered 205. 38 % response rate. Virginia Henderson was the more selected model (33%, however, 42% left the question blank, 12% indicated that they wanted to work under the guidance of a model. They selected a specifically model: Knowledge of the model to their training, standardization in other centers, the characteristics of the model itself and identification with its philosophy. They are not decided by a model by ignorance, lack of time and usefulness. CONCLUSIONS: The model chosen mostly for their daily work was Virginia Henderson model, so that knowledge of a model is the main reason for their election. Professionals who choose not to use the model in their practice realize offers and calling for resources, besides to explain the lack of knowledge on this topic. To advance the nursing profession is necessary that nurse is thought over widely on the abstract concepts of the theory in our context.
Directory of Open Access Journals (Sweden)
Hadeed A. Sher
2017-04-01
Full Text Available In this paper theoretical and experimental analysis of an AC–DC–AC inverter under DC link capacitor failure is presented. The failure study conducted for this paper is the open circuit of the DC link capacitor. The presented analysis incorporates the results for both single and three phase AC input. It has been observed that the higher ripple frequency provides better ride through capability for this fault. Furthermore, the effects of this fault on electrical characteristics of AC–DC–AC inverter and mechanical properties of the induction motor are also presented. Moreover, the effect of pulsating torque as a result of an open circuited DC link capacitor is also taken into consideration. Theoretical analysis is supported by computer aided simulation as well as with a real time experimental prototype.
Theoretical Models of Deliberative Democracy: A Critical Analysis
Directory of Open Access Journals (Sweden)
Tutui Viorel
2015-07-01
Full Text Available Abstract: My paper focuses on presenting and analyzing some of the most important theoretical models of deliberative democracy and to emphasize their limits. Firstly, I will mention James Fishkin‟s account of deliberative democracy and its relations with other democratic models. He differentiates between four democratic theories: competitive democracy, elite deliberation, participatory democracy and deliberative democracy. Each of these theories makes an explicit commitment to two of the following four “principles”: political equality, participation, deliberation, nontyranny. Deliberative democracy is committed to political equality and deliberation. Secondly, I will present Philip Pettit‟s view concerning the main constraints of deliberative democracy: the inclusion constraint, the judgmental constraint and the dialogical constraint. Thirdly, I will refer to Amy Gutmann and Dennis Thompson‟s conception regarding the “requirements” or characteristics of deliberative democracy: the reason-giving requirement, the accessibility of reasons, the binding character of the decisions and the dynamic nature of the deliberative process. Finally, I will discuss Joshua Cohen‟s “ideal deliberative procedure” which has the following features: it is free, reasoned, the parties are substantively equal and the procedure aims to arrive at rationally motivated consensus. After presenting these models I will provide a critical analysis of each one of them with the purpose of revealing their virtues and limits. I will make some suggestions in order to combine the virtues of these models, to transcend their limitations and to offer a more systematical account of deliberative democracy. In the next four sections I will take into consideration four main strategies for combining political and epistemic values (“optimistic”, “deliberative”, “democratic” and “pragmatic” and the main objections they have to face. In the concluding section
A survey of game-theoretic models of cooperative advertising
DEFF Research Database (Denmark)
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...... parts. The first one deals with simple marketing channels having one supplier and one reseller only. The second one covers marketing channels of a more complex structure, having more than one supplier and/or reseller. In the first part we find that a number of results carry over from static to dynamic...... problems of cooperative advertising also shows some similarities. The second part shows that models incorporating horizontal interaction on either or both layers of the supply chain are much less numerous than those supposing its absence. Participation rates in co-op advertising programs depend on inter...
Spatial Segregation, Redistribution and Welfare: A Theoretical Model
Directory of Open Access Journals (Sweden)
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.
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...
Simple Brownian diffusion an introduction to the standard theoretical models
Gillespie, Daniel T
2013-01-01
Brownian diffusion, the motion of large molecules in a sea of very many much smaller molecules, is topical because it is one of the ways in which biologically important molecules move about inside living cells. This book presents the mathematical physics that underlies the four simplest models of Brownian diffusion.
Mayer, W.; Labani, R.; Kruelle, G.
1992-07-01
Theoretical investigations are described, explaining details of high-pressure H2/O2 coaxial injection. The stochastic separated flow model is used to study and quantify turbulent gas/droplet interaction. Central point of investigation is the contribution of gas turbulence to droplet dispersion in space and velocity. Spray computations in idealized homogeneous turbulent gas fields with parameter variations and in realistic flows were performed. Studies concerning droplet break-up using simplified model assumptions are presented. Proof has been obtained of the importance of Saffman Lift to droplet motion.
International Nuclear Information System (INIS)
Wang Wei; Liu Gongqiang; Wang Jinhui
2006-01-01
The magnetic property in neodymium gallium garnet (NdGaG) is studied by the quantum theory. The ground configuration split states are calculated taking into account the spin-orbit interaction and crystal field effect. Taking account of the Nd-Nd exchange interaction, a good agreement between experimental and theoretical values can be obtained for the variation of the magnetic moment with the external magnetic field under 'extreme' conditions (low temperature and high magnetic field). Moreover, the temperature dependence of magnetic moment and the magnetic susceptibility χ is also discussed. Above 30 K, the magnetization (M) shows a linear field (H e ) dependence
A theoretical study of bone remodelling under PEMF at cellular level.
Wang, Yanan; Qin, Qing-Hua
2012-01-01
Pulsed electromagnetic field (PEMF) devices have been used clinically to slow down osteoporosis and accelerate the healing of bone fractures for many years. However, the underlying mechanism by which bone remodelling under PEMF is regulated remains poorly understood. In this paper, a mathematical model of bone cell population of bone remodelling under PEMF at cellular level is developed to address this issue for the first time. On the basis of this model and control theory, parametric study of control mechanisms is carried out and a number of possible control mechanisms are identified. These findings will help further the understanding of bone remodelling under PEMF and advance therapies and pharmacological developments in clinical trials.
A theoretical intellectual capital model applied to cities
Directory of Open Access Journals (Sweden)
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
Directory of Open Access Journals (Sweden)
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.
Modeling opinion dynamics: Theoretical analysis and continuous approximation
International Nuclear Information System (INIS)
Pinasco, Juan Pablo; Semeshenko, Viktoriya; Balenzuela, Pablo
2017-01-01
Highlights: • We study a simple model of persuasion dynamics with long range pairwise interactions. • The continuous limit of the master equation is a nonlinear, nonlocal, first order partial differential equation. • We compute the analytical solutions to this equation, and compare them with the simulations of the dynamics. - Abstract: 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 and the agreement is reached because the new arguments are incorporated. Given the wide range of opinion formation mathematical approaches, there are however no models of opinion dynamics with nonlocal pair interactions analytically solvable. In this paper we present a novel analytical framework developed to solve the master equations with non-local kernels. For this we used a simple model of opinion formation where individuals tend to get more similar after each interactions, no matter their opinion differences, giving rise to nonlinear differential master equation with non-local terms. Simulation results show an excellent agreement with results obtained by the theoretical estimation.
Haldane model under nonuniform strain
Ho, Yen-Hung; Castro, Eduardo V.; Cazalilla, Miguel A.
2017-10-01
We study the Haldane model under strain using a tight-binding approach, and compare the obtained results with the continuum-limit approximation. As in graphene, nonuniform strain leads to a time-reversal preserving pseudomagnetic field that induces (pseudo-)Landau levels. Unlike a real magnetic field, strain lifts the degeneracy of the zeroth pseudo-Landau levels at different valleys. Moreover, for the zigzag edge under uniaxial strain, strain removes the degeneracy within the pseudo-Landau levels by inducing a tilt in their energy dispersion. The latter arises from next-to-leading order corrections to the continuum-limit Hamiltonian, which are absent for a real magnetic field. We show that, for the lowest pseudo-Landau levels in the Haldane model, the dominant contribution to the tilt is different from graphene. In addition, although strain does not strongly modify the dispersion of the edge states, their interplay with the pseudo-Landau levels is different for the armchair and zigzag ribbons. Finally, we study the effect of strain in the band structure of the Haldane model at the critical point of the topological transition, thus shedding light on the interplay between nontrivial topology and strain in quantum anomalous Hall systems.
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).
posttraumatic stress disorder: a theoretical model of the hyperarousal subtype
Directory of Open Access Journals (Sweden)
Charles Stewart Weston
2014-04-01
Full Text Available Posttraumatic stress disorder (PTSD is a frequent and distressing mental disorder, about which much remains to be learned. It is a heterogeneous disorder; the hyperarousal subtype (about 70% of occurrences and simply termed PTSD in this paper is the topic of this article, but the dissociative subtype (about 30% of occurrences and likely involving quite different brain mechanisms is outside its scope. A theoretical model is presented that integrates neuroscience data on diverse brain regions known to be involved in PTSD, and extensive psychiatric findings on the disorder. Specifically, the amygdala is a multifunctional brain region that is crucial to PTSD, and processes peritraumatic hyperarousal on grounded cognition principles to produce hyperarousal symptoms. Amygdala activity also modulates hippocampal function, which is supported by a large body of evidence, and likewise amygdala activity modulates several brainstem regions, visual cortex, rostral anterior cingulate cortex (rACC, and medial orbitofrontal cortex (mOFC, to produce diverse startle, visual, memory, numbing, anger, and recklessness symptoms. Additional brain regions process other aspects of peritraumatic responses to produce further symptoms. These contentions are supported by neuroimaging, neuropsychological, neuroanatomical, physiological, cognitive, and behavioral evidence. Collectively, the model offers an account of how responses at the time of trauma are transformed into an extensive array of the 20 PTSD symptoms that are specified in the Diagnostic and Statistical Manual of Mental Disorders, 5th edition. It elucidates the neural mechanisms of a specific form of psychopathology, and accords with the Research Domain Criteria framework
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.
Experimental Investigation and Theoretical Modeling of Nanosilica Activity in Concrete
Directory of Open Access Journals (Sweden)
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.
Theoretical Modelling Methods for Thermal Management of Batteries
Directory of Open Access Journals (Sweden)
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 for analysing gender bias in medicine
Directory of Open Access Journals (Sweden)
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.
A theoretical model for analysing gender bias in medicine.
Risberg, Gunilla; Johansson, Eva E; Hamberg, Katarina
2009-08-03
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.
Nonlinear local electrovascular coupling. I: A theoretical model.
Riera, Jorge J; Wan, Xiaohong; Jimenez, Juan Carlos; Kawashima, Ryuta
2006-11-01
Here we present a detailed biophysical model of how brain electrical and vascular dynamics are generated within a basic cortical unit. The model was obtained from coupling a canonical neuronal mass and an expandable vasculature. In this proposal, we address several aspects related to electroencephalographic and functional magnetic resonance imaging data fusion: (1) the impact of the cerebral architecture (at different physical levels) on the observations; (2) the physiology involved in electrovascular coupling; and (3) energetic considerations to gain a better understanding of how the glucose budget is used during neuronal activity. The model has three components. The first is the canonical neural mass model of three subpopulations of neurons that respond to incoming excitatory synaptic inputs. The generation of the membrane potentials in the somas of these neurons and the electric currents flowing in the neuropil are modeled by this component. The second and third components model the electrovascular coupling and the dynamics of vascular states in an extended balloon approach, respectively. In the first part we describe, in some detail, the biophysical model and establish its face validity using simulations of visually evoked responses under different flickering frequencies and luminous contrasts. In a second part, a recursive optimization algorithm is developed and used to make statistical inferences about this forward/generative model from actual data. Copyright 2006 Wiley-Liss, Inc.
Ward, Nicholas J; Schell, William; Kelley-Baker, Tara; Otto, Jay; Finley, Kari
2018-01-16
This study explored a theoretical model to assess the influence of culture on willingness and intention to drive under the influence of cannabis (DUIC). This model is expected to guide the design of strategies to change future DUIC behavior in road users. This study used a survey methodology to obtain a nationally representative sample (n = 941) from the AmeriSpeak Panel. Survey items were designed to measure aspects of a proposed definition of traffic safety culture and a predictive model of its relationship to DUIC. Although the percentage of reported past DUIC behaviors was relatively low (8.5%), this behavior is still a significant public health issue-especially for younger drivers (18-29 years), who reported more DUIC than expected. Findings suggest that specific cultural components (attitudes, norms) reliably predict past DUIC behavior, general DUIC willingness, and future DUIC intention. Most DUIC behavior appears to be deliberate, related significantly to willingness and intention. Intention and willingness both appear to fully moderate the relationship between traffic safety culture and DUIC behavior. This study explored a theoretical model to understand road user behavior involving drug (cannabis)-impaired driving as a significant risk factor for traffic safety. By understanding the cultural factors that increase DUIC behavior, we can create strategies to transform this culture and sustain safer road user behavior.
French, Kenneth W., Jr.
1986-01-01
The salient aspects of the theoretical modeling of a conventional triaxial test (CTC) of a cohesionless granular medium with stress and strain rate loading are described. Included are a controllable gravitational body force and provision for low confining pressure and/or very low intergranular stress. The modeling includes rational, analytic, and numerical phases, all in various stages of development. The numerical evolutions of theoretical models will be used in final design stages and in the analysis of the experimental data. In this the experimental design stage, it is of special interest to include in the candidate considerations every anomaly found in preliminary terrestrial experimentation. Most of the anomalies will be eliminated by design or enhanced for measurement as the project progresses. The main aspect of design being not the physical apparatus but the type and trajectories of loading elected. The major considerations that have been treated are: appearance and growth of local surface aberrations, stress-power coefficients, strain types, optical strain, radial bead migration, and measures of rotation for the proper stress flux.
Rigorous theoretical derivation of lumped models to transmission line systems
International Nuclear Information System (INIS)
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 γd, 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. (semiconductor integrated circuits)
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
Measures of metacognition on signal-detection theoretic models.
Barrett, Adam B; Dienes, Zoltan; Seth, Anil K
2013-12-01
Analyzing metacognition, specifically knowledge of accuracy of internal perceptual, memorial, or other knowledge states, is vital for many strands of psychology, including determining the accuracy of feelings of knowing and discriminating conscious from unconscious cognition. Quantifying metacognitive sensitivity is however more challenging than quantifying basic stimulus sensitivity. Under popular signal-detection theory (SDT) models for stimulus classification tasks, approaches based on Type II receiver-operating characteristic (ROC) curves or Type II d-prime risk confounding metacognition with response biases in either the Type I (classification) or Type II (metacognitive) tasks. A new approach introduces meta-d': The Type I d-prime that would have led to the observed Type II data had the subject used all the Type I information. Here, we (a) further establish the inconsistency of the Type II d-prime and ROC approaches with new explicit analyses of the standard SDT model and (b) analyze, for the first time, the behavior of meta-d' under nontrivial scenarios, such as when metacognitive judgments utilize enhanced or degraded versions of the Type I evidence. Analytically, meta-d' values typically reflect the underlying model well and are stable under changes in decision criteria; however, in relatively extreme cases, meta-d' can become unstable. We explore bias and variance of in-sample measurements of meta-d' and supply MATLAB code for estimation in general cases. Our results support meta-d' as a useful measure of metacognition and provide rigorous methodology for its application. Our recommendations are useful for any researchers interested in assessing metacognitive accuracy. PsycINFO Database Record (c) 2014 APA, all rights reserved.
Theoretic models for recommendation and implementation of assistive technology
Directory of Open Access Journals (Sweden)
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
Membranes and theoretical modeling of membrane distillation: a review.
Khayet, Mohamed
2011-05-11
Membrane distillation (MD) is one of the non-isothermal membrane separation processes used in various applications such desalination, environmental/waste cleanup, food, etc. It is known since 1963 and is still being developed at laboratory stage for different purposes and not fully implemented in industry. An abrupt increase in the number of papers on MD membrane engineering (i.e. design, fabrication and testing in MD) is seen since only 6 years ago. The present paper offers a comprehensive MD state-of-the-art review covering a wide range of commercial membranes, MD membrane engineering, their MD performance, transport mechanisms, experimental and theoretical modeling of different MD configurations as well as recent developments in MD. Improved MD membranes with specific morphology, micro- and nano-structures are highly demanded. Membranes with different pore sizes, porosities, thicknesses and materials as well as novel structures are required in order to carry out systematic MD studies for better understanding mass transport in different MD configurations, thereby improving the MD performance and looking for MD industrialization. Copyright © 2010 Elsevier B.V. All rights reserved.
Hybrid empirical--theoretical approach to modeling uranium adsorption
Energy Technology Data Exchange (ETDEWEB)
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.
Hybrid empirical--theoretical approach to modeling uranium adsorption
International Nuclear Information System (INIS)
Hull, Larry C.; Grossman, Christopher; Fjeld, Robert A.; Coates, John T.; Elzerman, Alan W.
2004-01-01
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 f parameter is correlated to sediment surface area (r 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
Activity systems modeling as a theoretical lens for social exchange studies
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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.
Ammonium Azide under High Pressure - a combined Theoretical and Experimental Study
Radousky, Harry; Crowhurst, Jonathan; Zaug, Joseph; Steele, Bradley; Landerville, Aaron; Oleynik, Ivan
2015-03-01
Efforts to synthesize, characterize and recover novel polynitrogen energetic materials have driven attempts to subject high nitrogen content precursor materials (in particular metal and non-metal azides) to elevated pressures. Here we present a combined theoretical and experimental study of the high pressure behavior of ammonium azide (NH4N3) . Using density functional theory we have considered the relative thermodynamic stability of the material with respect to two other crystal phases, namely trans-tetrazene (TTZ), and also a novel hydronitrogen solid (HNS) of the form (NH)4, that was recently predicted to become relatively stable under high pressure. Experimentally we have measured the Raman spectra of NH4N3 up to 71 GPa at room temperature. Our calculations demonstrate that the HNS becomes stable only at pressures much higher (89.4 GPa) than previously predicted (36 GPa). Our Raman spectra are consistent with earlier reports up to lower pressures, and at higher pressures, while some additional subtle behavior is observed (e.g. mode splitting) there is again no evidence of a phase transition to either TTZ or the HNS. Research performed under the auspices of the U.S. DOE by LLNL under Contract No. DE-AC52-07NA27344 (Work at USF and LLNL supported by DTRA Grant HDTRA1-12-1-0023). LLNL-JRNL-651736.
International Nuclear Information System (INIS)
Daum, E.
1996-10-01
In this report the applicability of light ion simulation irradiations with respect to the displacement damage under fusion neutron irradiation is investigated by theoretical and experimental activities. The production of primary knock-on atoms (PKA) and the displacement of lattice atoms (DPA) under proton and α-particle irradiation is considered in pure iron. The main focus is put on the effect of the non-elastic processes which are characterized by nuclear reactions and taken into account quantitatively for the first time. The profiles of the non-elastic PKA spectra can be characterized by the excitation functions of the corresponding nuclear reactions and by the mean recoil ranges of the residue nuclides. In this framework the excitation functions of proton- and α-particle-induced nuclear reactions leading to the long-lived nuclides from 57 Ni to 47 Sc are measured. The short-lived nuclides 53 Fe g , 53 Fe m , 52 Mn m and 52 V are investigated for the first time. The mean recoil ranges of the non-elastic PKA are experimentally determined by the same method. Based on theoretical calculations with nuclear and range models, non-elastic PKA spectra are obtained for all open reaction channels. (orig./WL)
Audiovisual Rehabilitation in Hemianopia: A Model-Based Theoretical Investigation
Magosso, Elisa; Cuppini, Cristiano; Bertini, Caterina
2017-01-01
translate visual stimuli into short-latency saccades, possibly moving the stimuli into visual detection regions. The retina-SC-extrastriate circuit is related to restitutive effects: visual stimuli can directly elicit visual detection with no need for eye movements. Model predictions and assumptions are critically discussed in view of existing behavioral and neurophysiological data, forecasting that other oculomotor compensatory mechanisms, beyond short-latency saccades, are likely involved, and stimulating future experimental and theoretical investigations. PMID:29326578
Audiovisual Rehabilitation in Hemianopia: A Model-Based Theoretical Investigation
Directory of Open Access Journals (Sweden)
Elisa Magosso
2017-12-01
circuit can translate visual stimuli into short-latency saccades, possibly moving the stimuli into visual detection regions. The retina-SC-extrastriate circuit is related to restitutive effects: visual stimuli can directly elicit visual detection with no need for eye movements. Model predictions and assumptions are critically discussed in view of existing behavioral and neurophysiological data, forecasting that other oculomotor compensatory mechanisms, beyond short-latency saccades, are likely involved, and stimulating future experimental and theoretical investigations.
Theoretical models for ultrashort electromagnetic pulse propagation in nonlinear metamaterials
International Nuclear Information System (INIS)
Wen, Shuangchun; Xiang, Yuanjiang; Dai, Xiaoyu; Tang, Zhixiang; Su, Wenhua; Fan, Dianyuan
2007-01-01
A metamaterial (MM) differs from an ordinary optical material mainly in that it has a dispersive magnetic permeability and offers greatly enhanced design freedom to alter the linear and nonlinear properties. This makes it possible for us to control the propagation of ultrashort electromagnetic pulses at will. Here we report on generic features of ultrashort electromagnetic pulse propagation and demonstrate the controllability of both the linear and nonlinear parameters of models for pulse propagation in MMs. First, we derive a generalized system of coupled three-dimensional nonlinear Schroedinger equations (NLSEs) suitable for few-cycle pulse propagation in a MM with both nonlinear electric polarization and nonlinear magnetization. The coupled equations recover previous models for pulse propagation in both ordinary material and a MM under the same conditions. Second, by using the coupled NLSEs in the Drude dispersive model as an example, we identify the respective roles of the dispersive electric permittivity and magnetic permeability in ultrashort pulse propagation and disclose some additional features of pulse propagation in MMs. It is shown that, for linear propagation, the sign and magnitude of space-time focusing can be controlled through adjusting the linear dispersive permittivity and permeability. For nonlinear propagation, the linear dispersive permittivity and permeability are incorporated into the nonlinear magnetization and nonlinear polarization, respectively, resulting in controllable magnetic and electric self-steepening effects and higher-order dispersively nonlinear terms in the propagation models
International Nuclear Information System (INIS)
Tsytovich, V N
2015-01-01
We review research aimed at understanding the phenomena occurring in a complex plasma under microgravity conditions. Some aspects of the work already performed are considered that have not previously been given sufficient attention but which are potentially crucial for future work. These aspects, in particular, include the observation of compact dust structures that are estimated to be capable of confining all components of a dust plasma in a bounded spatial volume; experimental evidence of the nonlinear screening of dust particles; and experimental evidence of the excitation of collective electric fields. In theoretical terms, novel collective attraction processes between likely charged dust particles are discussed and all schemes of the shadowy attraction between dust particles used earlier, including in attempts to interpret observations, are reviewed and evaluated. Dust structures are considered from the standpoint of the current self-organization theory. It is emphasized that phase transitions between states of self-organized systems differ significantly from those in homogeneous states and that the phase diagrams should be constructed in terms of the parameters of a self-organized structure and cannot be constructed in terms of the temperature and density or similar parameters of homogeneous structures. Using the existing theoretical approaches to modeling self-organized structures in dust plasmas, the parameter distribution of a structure is recalculated for a simpler model that includes the quasineutrality condition and neglects diffusion. These calculations indicate that under microgravity conditions, any self-organized structure can contain a limited number of dust particles and is finite in size. The maximum possible number of particles in a structure determines the characteristic inter-grain distance in dust crystals that can be created under microgravity conditions. Crystallization criteria for the structures are examined and the quasispherical
Saghir, Shahid
2017-04-07
We investigate the static and dynamic behavior of a multilayer clamped-free-clamped-free (CFCF) microplate, which is made of polyimide, gold, chromium, and nickel. The microplate is slightly curved away from a stationary electrode and is electrostatically actuated. The free and forced vibrations of the microplate are examined. First, we experimentally investigate the variation of the first natural frequency under the electrostatic DC load. Then, the forced dynamic behavior is investigated by applying a harmonic AC voltage superimposed to a DC voltage. Results are shown demonstrating the transition of the dynamic response of the microplate from hardening to softening as the DC voltage is changed as well the dynamic pull-in phenomenon. For theoretical model, we adopt a dynamic analog of the von-Karman governing equations accounting for initial curvature imperfection. These equations are then used to develop a reduced order model based on the Galerkin procedure to simulate the mechanical behavior of the microplate. We compare the theoretical results with experimental data and show excellent agreement among the results. We also examine the effect of the initial rise on the natural frequencies of first three symmetric-symmetric modes of the plate.
International Nuclear Information System (INIS)
Reivinen, M.; Freund, J.; Eloranta, E.
1996-08-01
The aim of the study is to model the geodynamic response of a ground rock block under horizontal stresses and also consider the thermal fields and deformations, especially on the ground surface, caused by the heat produced by nuclear waste. (12 refs.)
International Nuclear Information System (INIS)
Mardinoglu, Adil; Cregg, P.J.; Murphy, Kieran; Curtin, Maurice; Prina-Mello, Adriele
2011-01-01
The magnetisable stent assisted magnetic targeted drug delivery system in a physiologically stretched vessel is considered theoretically. The changes in the mechanical behaviour of the vessel are analysed under the influence of mechanical forces generated by blood pressure. In this 2D mathematical model a ferromagnetic, coiled wire stent is implanted to aid collection of magnetic drug carrier particles in an elastic tube, which has similar mechanical properties to the blood vessel. A cyclic mechanical force is applied to the elastic tube to mimic the mechanical stress and strain of both the stent and vessel while in the body due to pulsatile blood circulation. The magnetic dipole-dipole and hydrodynamic interactions for multiple particles are included and agglomeration of particles is also modelled. The resulting collection efficiency of the mathematical model shows that the system performance can decrease by as much as 10% due to the effects of the pulsatile blood circulation. - Research highlights: →Theoretical modelling of magnetic drug targeting on a physiologically stretched stent-vessel system. →Cyclic mechanical force applied to mimic the mechanical stress and strain of both stent and vessel. →The magnetic dipole-dipole and hydrodynamic interactions for multiple particles is modelled. →Collection efficiency of the mathematical model is calculated for different physiological blood flow and magnetic field strength.
Dedes, I.; Dudek, J.
2018-03-01
We examine the effects of the parametric correlations on the predictive capacities of the theoretical modelling keeping in mind the nuclear structure applications. The main purpose of this work is to illustrate the method of establishing the presence and determining the form of parametric correlations within a model as well as an algorithm of elimination by substitution (see text) of parametric correlations. We examine the effects of the elimination of the parametric correlations on the stabilisation of the model predictions further and further away from the fitting zone. It follows that the choice of the physics case and the selection of the associated model are of secondary importance in this case. Under these circumstances we give priority to the relative simplicity of the underlying mathematical algorithm, provided the model is realistic. Following such criteria, we focus specifically on an important but relatively simple case of doubly magic spherical nuclei. To profit from the algorithmic simplicity we chose working with the phenomenological spherically symmetric Woods–Saxon mean-field. We employ two variants of the underlying Hamiltonian, the traditional one involving both the central and the spin orbit potential in the Woods–Saxon form and the more advanced version with the self-consistent density-dependent spin–orbit interaction. We compare the effects of eliminating of various types of correlations and discuss the improvement of the quality of predictions (‘predictive power’) under realistic parameter adjustment conditions.
System of systems dependability – Theoretical models and applications examples
International Nuclear Information System (INIS)
Bukowski, L.
2016-01-01
The aim of this article is to generalise the concept of "dependability" in a way, that could be applied to all types of systems, especially the system of systems (SoS), operating under both normal and abnormal work conditions. In order to quantitatively assess the dependability we applied service continuity oriented approach. This approach is based on the methodology of service engineering and is closely related to the idea of resilient enterprise as well as to the concept of disruption-tolerant operation. On this basis a framework for evaluation of SoS dependability has been developed in a static as well as dynamic approach. The static model is created as a fuzzy logic-oriented advisory expert system and can be particularly useful at the design stage of SoS. The dynamic model is based on the risk oriented approach, and can be useful both at the design stage and for management of SoS. The integrated model of dependability can also form the basis for a new definition of the dependability engineering, namely as a superior discipline to reliability engineering, safety engineering, security engineering, resilience engineering and risk engineering. - Highlights: • A framework for evaluation of system of systems dependability is presented. • The model is based on the service continuity concept and consists of two parts. • The static part can be created as a fuzzy logic-oriented advisory expert system. • The dynamic, risk oriented part, is related to the concept of throughput chain. • A new definition of dependability engineering is proposed.
A theoretical microbial contamination model for a human Mars mission
Lupisella, Mark Lewis
Contamination from a human presence on Mars could significantly compromise the search for extraterrestrial life. In particular, the difficulties in controlling microbial contamination, the potential for terrestrial microbes to grow, evolve, compete, and modify the Martian environment, and the likely microbial nature of putative Martian life, make microbial contamination worthy of focus as we begin to plan for a human mission to Mars. This dissertation describes a relatively simple theoretical model that can be used to explore how microbial contamination from a human Mars mission might survive and grow in the Martian soil environment surrounding a habitat. A user interface has been developed to allow a general practitioner to choose values and functions for almost all parameters ranging from the number of astronauts to the half-saturation constants for microbial growth. Systematic deviations from a baseline set of parameter values are explored as potential plausible scenarios for the first human Mars missions. The total viable population and population density are the primary state variables of interest, but other variables such as the total number of births and total dead and viable microbes are also tracked. The general approach was to find the most plausible parameter value combinations that produced a population density of 1 microbe/cm3 or greater, a threshold that was used to categorize the more noteworthy populations for subsequent analysis. Preliminary assessments indicate that terrestrial microbial contamination resulting from leakage from a limited human mission (perhaps lasting up to 5 months) will not likely become a problematic population in the near-term as long as reasonable contamination control measures are implemented (for example, a habitat leak rate no greater than 1% per hour). However, there appear to be plausible, albeit unlikely, scenarios that could cause problematic populations, depending in part on (a) the initial survival fraction and
A P-value model for theoretical power analysis and its applications in multiple testing procedures
Directory of Open Access Journals (Sweden)
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.
Experimental and theoretical study of magnetohydrodynamic ship models.
Cébron, David; Viroulet, Sylvain; Vidal, Jérémie; Masson, Jean-Paul; Viroulet, Philippe
2017-01-01
Magnetohydrodynamic (MHD) ships represent a clear demonstration of the Lorentz force in fluids, which explains the number of students practicals or exercises described on the web. However, the related literature is rather specific and no complete comparison between theory and typical small scale experiments is currently available. This work provides, in a self-consistent framework, a detailed presentation of the relevant theoretical equations for small MHD ships and experimental measurements for future benchmarks. Theoretical results of the literature are adapted to these simple battery/magnets powered ships moving on salt water. Comparison between theory and experiments are performed to validate each theoretical step such as the Tafel and the Kohlrausch laws, or the predicted ship speed. A successful agreement is obtained without any adjustable parameter. Finally, based on these results, an optimal design is then deduced from the theory. Therefore this work provides a solid theoretical and experimental ground for small scale MHD ships, by presenting in detail several approximations and how they affect the boat efficiency. Moreover, the theory is general enough to be adapted to other contexts, such as large scale ships or industrial flow measurement techniques.
Experimental and theoretical study of magnetohydrodynamic ship models.
Directory of Open Access Journals (Sweden)
David Cébron
Full Text Available Magnetohydrodynamic (MHD ships represent a clear demonstration of the Lorentz force in fluids, which explains the number of students practicals or exercises described on the web. However, the related literature is rather specific and no complete comparison between theory and typical small scale experiments is currently available. This work provides, in a self-consistent framework, a detailed presentation of the relevant theoretical equations for small MHD ships and experimental measurements for future benchmarks. Theoretical results of the literature are adapted to these simple battery/magnets powered ships moving on salt water. Comparison between theory and experiments are performed to validate each theoretical step such as the Tafel and the Kohlrausch laws, or the predicted ship speed. A successful agreement is obtained without any adjustable parameter. Finally, based on these results, an optimal design is then deduced from the theory. Therefore this work provides a solid theoretical and experimental ground for small scale MHD ships, by presenting in detail several approximations and how they affect the boat efficiency. Moreover, the theory is general enough to be adapted to other contexts, such as large scale ships or industrial flow measurement techniques.
Directory of Open Access Journals (Sweden)
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.
International Nuclear Information System (INIS)
Lu, Xiaodong; Wu, Yingwei; Zhou, Linglan; Tian, Wenxi; Su, Guanghui; Qiu, Suizheng; Zhang, Hong
2014-01-01
Highlights: • We developed a model based on homogeneous flow model to analyze two-phase flow instability in parallel channels. • The influence of axial non-uniform heating on the system stability has been investigated. • Influences of various factors on system instability under cosine heat flux have been studied. • The system under top-peaked heat flux is the most stable system. - Abstract: Two-phase flow instability in parallel channels heated by axial non-uniform heat flux has been theoretically studied in this paper. The system control equations of parallel channels were established based on the homogeneous flow model in two-phase region. Semi-implicit finite-difference scheme and staggered mesh method were used to discretize the equations, and the difference equations were solved by chasing method. Cosine, bottom-peaked and top-peaked heat fluxes were used to study the influence of non-uniform heating on two-phase flow instability of the parallel channels system. The marginal stability boundaries (MSB) of parallel channels and three-dimensional instability spaces (or instability reefs) under different heat flux conditions have been obtained. Compared with axial uniform heating, axial non-uniform heating will affect the system stability. Cosine and bottom-peaked heat fluxes can destabilize the system stability in high inlet subcooling region, while the opposite effect can be found in low inlet subcooling region. However, top-peaked heat flux can enhance the system stability in the whole region. In addition, for cosine heat flux, increasing the system pressure or inlet resistance coefficient can strengthen the system stability, and increasing the heating power will destabilize the system stability. The influence of inlet subcooling number on the system stability is multi-valued under cosine heat flux
Determining Student Competency in Field Placements: An Emerging Theoretical Model
Directory of Open Access Journals (Sweden)
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
Directory of Open Access Journals (Sweden)
Chenguang Shi
2018-04-01
Full Text Available This paper presents a novel Nash bargaining solution (NBS-based cooperative game-theoretic framework for power control in a distributed multiple-radar architecture underlying a wireless communication system. Our primary objective is to minimize the total power consumption of the distributed multiple-radar system (DMRS with the protection of wireless communication user’s transmission, while guaranteeing each radar’s target detection requirement. A unified cooperative game-theoretic framework is proposed for the optimization problem, where interference power constraints (IPCs are imposed to protect the communication user’s transmission, and a minimum signal-to-interference-plus-noise ratio (SINR requirement is employed to provide reliable target detection for each radar. The existence, uniqueness and fairness of the NBS to this cooperative game are proven. An iterative Nash bargaining power control algorithm with low computational complexity and fast convergence is developed and is shown to converge to a Pareto-optimal equilibrium for the cooperative game model. Numerical simulations and analyses are further presented to highlight the advantages and testify to the efficiency of our proposed cooperative game algorithm. It is demonstrated that the distributed algorithm is effective for power control and could protect the communication system with limited implementation overhead.
International Nuclear Information System (INIS)
Jia Su; Wang Xi-Shu; Ren Huai-Hui
2012-01-01
High density packaging is developing toward miniaturization and integration, which causes many difficulties in designing, manufacturing, and reliability testing. Package-on-Package (PoP) is a promising three-dimensional high-density packaging method that integrates a chip scale package (CSP) in the top package and a fine-pitch ball grid array (FBGA) in the bottom package. In this paper, in-situ scanning electron microscopy (SEM) observation is carried out to detect the deformation and damage of the PoP structure under three-point bending loading. The results indicate that the cracks occur in the die of the top package, then cause the crack deflection and bridging in the die attaching layer. Furthermore, the mechanical principles are used to analyse the cracking process of the PoP structure based on the multi-layer laminating hypothesis and the theoretical analysis results are found to be in good agreement with the experimental results. (condensed matter: structural, mechanical, and thermal properties)
Theoretical Modeling of the Surface-Enhanced Raman Optical Activity
Czech Academy of Sciences Publication Activity Database
Novák, Vít; Šebestík, Jaroslav; Bouř, Petr
2012-01-01
Roč. 8, č. 5 (2012), s. 1714-1720 ISSN 1549-9618 R&D Projects: GA ČR GAP208/11/0105; GA MŠk(CZ) LH11033 Institutional research plan: CEZ:AV0Z40550506 Keywords : vibrational spectroscopy * absolute-configuration * silver electrode * spectra * scattering * pyridine Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.389, year: 2012
Theoretical Model of Engagement in the Context of Brand Communities
Flávia D\\u2019albergaria Freitas; Victor Manoel Cunha de Almeida
2017-01-01
This essay proposes to refine the concept of consumer engagement in the context of brand communities. A comprehensive review of studies addressing the phenomenon of brand community was made. This paper follows the tradition of Marketing Research and Consumer Behavior, more specifically the perspective of cognitive psychology. The main theoretical foundation of the study is the Social Identity Theory (SIT), also incorporating relevant contributions from the perspective of Consumer Culture Theo...
A theoretical model for metal-graphene contact resistance using a DFT-NEGF method.
Ji, Xiang; Zhang, Jinyu; Wang, Yan; Qian, He; Yu, Zhiping
2013-11-07
The contact resistance (R(c)) between graphene and metal electrodes is of crucial importance for achieving potentially high performances for graphene devices. However, previous analytical models based on Landauer's approach have failed to include the Fermi velocity difference between the graphene under the metal and the pure graphene channel. Hereby we report a theoretical model to estimate the R(c) using density-functional theory and non-equilibrium Green's function methods. Our model not only presents a clear physical picture of the metal-graphene contacts, but also generates R(c) values which are in good agreement with the experimental results: 210 Ω μm for double-sided Pd contacts compared with 403 Ω μm for single-sided Pd contact.
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%.
A new theoretical model for scattering of electrons by molecules. 1
International Nuclear Information System (INIS)
Peixoto, E.M.A.; Mu-tao, L.; Nogueira, J.C.
1975-01-01
A new theoretical model for electron-molecule scattering is suggested. The e-H 2 scattering is studied and the superiority of the new model over the commonly used Independent Atom Model (IAM) is demonstrated. Comparing theoretical and experimental data for 40keV electrons scattered by H 2 utilizing the new model, its validity is proved, while Partial Wave and First Born calculations, employing the Independent Atom Model, strongly deviated from the experiment [pt
Zhumasheva, Anara; Zhumabaeva, Zaida; Sakenov, Janat; Vedilina, Yelena; Zhaxylykova, Nuriya; Sekenova, Balkumis
2016-01-01
The current study focuses on the research topic of creating a theoretical model of development of information competence among students enrolled in elective courses. In order to examine specific features of the theoretical model of development of information competence among students enrolled in elective courses, we performed an analysis of…
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…
Directory of Open Access Journals (Sweden)
Vijay Kumar
2016-12-01
Full Text Available This paper outlines the quality inspection strategies in a supplier–buyer supply chain under a customer return policy. This paper primarily focuses on product quality and quality inspection techniques to maximize the actors’ and supply chain’s profits using game theory approach. The supplier–buyer setup is described in terms of textile manufacturer–retailer supply chain where quality inspection is an important aspect and the product return from the customer is generally accepted. Textile manufacturer produces the product, whereas, retailer acts as a reseller who buys the products from the textile manufacturer and sells them to the customers. In this context, the former invests in the product quality whereas the latter invests in the random quality inspection and traceability. The relationships between the textile manufacturer and the retailer are recognized as horizontal and vertical alliances and modeled using non-cooperative and cooperative games. The non-cooperative games are based on the Stackelberg and Nash equilibrium models. Further, bargaining and game change scenarios have been discussed to maximize the profit under different games. To understand the appropriateness of a strategic alliance, a computational study demonstrates textile manufacturer–retailer relation under different game scenarios.
Consistency of the MLE under mixture models
Chen, Jiahua
2016-01-01
The large-sample properties of likelihood-based statistical inference under mixture models have received much attention from statisticians. Although the consistency of the nonparametric MLE is regarded as a standard conclusion, many researchers ignore the precise conditions required on the mixture model. An incorrect claim of consistency can lead to false conclusions even if the mixture model under investigation seems well behaved. Under a finite normal mixture model, for instance, the consis...
Devi, Anita; De, Arijit K.
2017-08-01
Experimental evidence indicates that high-repetition-rate ultrafast pulsed excitation is more efficient in optical trapping of dielectric nanoparticles as compared with continuous-wave excitation at the same average power. The physics behind the different nature of force under these two excitation conditions remained deceptive until quite recently when it was theoretically explained, in the dipole limit, as a combined effect of (1) repetitive instantaneous momentum transfer and (2) optical Kerr nonlinearity. The role of optical Kerr effect was theoretically studied for larger dielectric spherical particles, in the ray optics limit, also. However, a theoretical underpinning is yet to be established as to whether the effect of optical nonlinearity is omnipresent across different particle sizes, which we investigate here. Using localized approximation of generalized Lorenz-Mie theory, we theoretically analyze the nature of force (and potential) and provide a detailed comparative discussion between this generalized scattering formulation with dipole scattering formulation for dielectric nanoparticles.
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.
Energy Technology Data Exchange (ETDEWEB)
Eisner, A.D. [Alion Science and Technology, P.O. Box 12313, Durham, NC 27709 (United States); Rosati, J.; Wiener, R. [National Homeland Security Research Center, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (United States)
2010-04-15
This research effort was aimed at understanding how foot motion affects air transport and thus how walking affects contaminant dispersion. Particle imaging velocimetry (PIV) showed that during a rotational motion of the foot (typical footstep), a draft corner flow develops that carries particles from heel to toe. Foot contact with the floor may result in one or both of two types of reentrainment: (1) particles become airborne due to detachment from the floor, and (2) particles are first collected by the foot cover (e.g., Tyvek) and then detached from the foot into the airflow produced by the foot rotation. The airflow under the rotating foot was modeled as a rotating corner flow, and it was shown that such modeling can capture major characteristics of the airflow generated by the rotating foot and can explain how rotational foot motion contributes to reentrainment and dispersion of contaminants. (author)
Chemical model reduction under uncertainty
Malpica Galassi, Riccardo
2017-03-06
A general strategy for analysis and reduction of uncertain chemical kinetic models is presented, and its utility is illustrated in the context of ignition of hydrocarbon fuel–air mixtures. The strategy is based on a deterministic analysis and reduction method which employs computational singular perturbation analysis to generate simplified kinetic mechanisms, starting from a detailed reference mechanism. We model uncertain quantities in the reference mechanism, namely the Arrhenius rate parameters, as random variables with prescribed uncertainty factors. We propagate this uncertainty to obtain the probability of inclusion of each reaction in the simplified mechanism. We propose probabilistic error measures to compare predictions from the uncertain reference and simplified models, based on the comparison of the uncertain dynamics of the state variables, where the mixture entropy is chosen as progress variable. We employ the construction for the simplification of an uncertain mechanism in an n-butane–air mixture homogeneous ignition case, where a 176-species, 1111-reactions detailed kinetic model for the oxidation of n-butane is used with uncertainty factors assigned to each Arrhenius rate pre-exponential coefficient. This illustration is employed to highlight the utility of the construction, and the performance of a family of simplified models produced depending on chosen thresholds on importance and marginal probabilities of the reactions.
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
DEFF Research Database (Denmark)
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...
Energy Technology Data Exchange (ETDEWEB)
Barashev, Alexander V [ORNL; Golubov, Stanislav I [ORNL; Stoller, Roger E [ORNL
2012-06-01
This work is based on our reaction-diffusion model of radiation growth of Zr-based materials proposed recently in [1]. In [1], the equations for the strain rates in unloaded pure crystal under cascade damage conditions of, e.g., neutron or heavy-ion irradiation were derived as functions of dislocation densities, which include contributions from dislocation loops, and spatial distribution of their Burgers vectors. The model takes into account the intra-cascade clustering of self-interstitial atoms and their one-dimensional diffusion; explains the growth stages, including the break-away growth of pre-annealed samples; and accounts for some striking observations, such as of negative strain in prismatic direction, and co-existence of vacancy- and interstitial-type prismatic loops. In this report, the change of dislocation densities due to accumulation of sessile dislocation loops is taken into account explicitly to investigate the dose dependence of radiation growth. The dose dependence of climb rates of dislocations is calculated, which is important for the climb-induced glide model of radiation creep. The results of fitting the model to available experimental data and some numerical calculations of the strain behavior of Zr for different initial dislocation structures are presented and discussed. The computer code RIMD-ZR.V1 (Radiation Induced Microstructure and Deformation of Zr) developed is described and attached to this report.
Energy Technology Data Exchange (ETDEWEB)
Yan Binghuo [Department of Nuclear Science and Engineering, Naval University of Engineering, Wuhan 430033 (China)], E-mail: yanbh1986@163.com; Yu Lei [Department of Nuclear Science and Engineering, Naval University of Engineering, Wuhan 430033 (China)], E-mail: yulei301@163.com
2009-06-15
Based on the two-phase drift flux model and the multi-pressure nodes matrix solving method, natural circulation thermal hydraulic analysis models for the Nuclear Machinery (NM) under ocean conditions are developed. The neutron physical activities and the responses of the reactivity control systems are described by the two-group, 3-dimensional space and time dependent neutron kinetics model. Reactivity feedback is calculated by coupling the neutron physics and thermal hydraulic codes, and is tested by comparison with experiments. Using the models developed, the natural circulation operating characteristics of NM in rolling and pitching motions and the transitions between forced circulation (FC) to natural circulation (NC) are analyzed. The results show that the influence of the rolling motion increases as the rolling amplitude is increased, and as the rolling period becomes shorter. The results also show that for this NM, with the same rolling period and rolling angle, the influence of pitching motion on natural circulation is greater than that of rolling motion. Furthermore, the oscillation period for pitching motion is the same as the pitching period, while the oscillation period for rolling is one half of the rolling period. In the ocean environment, excessive flow oscillation of the natural circulation may cause the control rods to respond so frequently that the NM would not be able to realize the transition from the FC to NC steadily. However, the influence of ocean environment on the transition from NC to FC is limited.
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.
Nishigawa, G; Maruo, Y; Irie, M; Oka, M; Tamada, Y; Minagi, S
2013-05-01
A theoretical model, based on fluid dynamics, was developed to measure impression pressure. The purpose of this study was to evaluate the validity of this theoretical model by comparing its theoretical analysis against actual pressure measurements conducted using an impression tray and edentulous oral mucosa analog embedded with pressure sensors. In the theoretical model, a hollow tube was mounted onto an impression tray by penetrating through the tray. When force was applied to the tray, pressure was produced which then caused the impression material to flow into the hollow tube. Length of impression material which flowed into tube was denoted as l. In the calculation formula for theoretical model, pressure impulse I was expressed as a function of impression flow length l. For actual pressure measurements, four electric pressure sensors were embedded in an experimental edentulous arch. To visually observe and measure length of impression material flow, four transparent silicon tubes were mounted vertically at different positions on tray. During tray seating, impression material flowed into tubes and pressure which caused material flow movement was measured by the embedded sensor at each tube's position. Based on actual pressure measurements under one experimental condition, regression analysis of pressure data acquired from electric sensors yielded the formula, Y=0.056X²+0.124X. Based on theoretical analysis using a particular viscosity value, the numerical formula yielded was Y=0.057X², which resembled that of the regression formula. Theoretical model presented in this paper augured well for clinical application as an easy and economical means to examine magnitude and distribution of impression pressure by measuring lengths of impression material flow in tubes fixed to impression tray. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
Theoretical models of magnetic field line merging. I
International Nuclear Information System (INIS)
Vasyliunas, V.M.
1975-01-01
Models of magnetic field line merging that consider processes in a limited region around the magnetic X line, within which the external magnetic fields are roughly uniform and antiparallel, are reviewed. Part I describes the concept of magnetic merging and then considers the models based on a hydromagnetic approach. The models developed by Sweet and Parker, by Petschek, and by Sonnerup and Yeh and Axford are shown to be fundamentally consistent, representing different aspects of the same problem. The model of Sweet and Parker describes the small region around the neutral line where magnetic field diffusion is the dominant process. The inclusion of inertial as well as finite resistivity effects allows an extension of their model to collisionless plasmas. Petschek's model represents a system with a boundary condition of uniform field at the sides; it has been extended and formulated in a mathematically precise manner. The nonsingular model of Sonnerup and of Yeh and Axford has special boundary conditions at the sides producing localized slow mode MHD expansion fans in the external flow; the singular models and the compressible similarity models are physically unrealizable. The maximum merging rate corresponds to flow into the diffusion region of the local Alfven speed, which, however, can be made arbitrarily large by slow mode MHD expansion if suitable boundary condi []ions are present. (auth)
Modeling and Simulation Fundamentals Theoretical Underpinnings and Practical Domains
Sokolowski, John A
2010-01-01
An insightful presentation of the key concepts, paradigms, and applications of modeling and simulation. Modeling and simulation has become an integral part of research and development across many fields of study, having evolved from a tool to a discipline in less than two decades. Modeling and Simulation Fundamentals offers a comprehensive and authoritative treatment of the topic and includes definitions, paradigms, and applications to equip readers with the skills needed to work successfully as developers and users of modeling and simulation. Featuring contributions written by leading experts
Hydrophobic ampersand hydrophilic: Theoretical models of solvation for molecular biophysics
International Nuclear Information System (INIS)
Pratt, L.R.; Tawa, G.J.; Hummer, G.; Garcia, A.E.; Corcelli, S.A.
1996-01-01
Molecular statistical thermodynamic models of hydration for chemistry and biophysics have advanced abruptly in recent years. With liquid water as solvent, salvation phenomena are classified as either hydrophobic or hydrophilic effects. Recent progress in treatment of hydrophilic effects have been motivated by continuum dielectric models interpreted as a modelistic implementation of second order perturbation theory. New results testing that perturbation theory of hydrophilic effects are presented and discussed. Recent progress in treatment of hydrophobic effects has been achieved by applying information theory to discover models of packing effects in dense liquids. The simplest models to which those ideas lead are presented and discussed
International Nuclear Information System (INIS)
Li, Huajiao; An, Haizhong; Fang, Wei; Jiang, Meng
2017-01-01
The logistical issues surrounding the timing and transport of flowback generated by each shale gas well to the next is a big challenge. Due to more and more flowback being stored temporarily near the shale gas well and reused in the shale gas development, both transportation cost and storage cost are the heavy burden for the developers. This research proposed a theoretical cost optimization model to get the optimal flowback distribution solution for regional multi shale gas wells in a holistic perspective. Then, we used some empirical data of Marcellus Shale to do the empirical study. In addition, we compared the optimal flowback distribution solution by considering both the transportation cost and storage cost with the flowback distribution solution which only minimized the transportation cost or only minimized the storage cost. - Highlights: • A theoretical cost optimization model to get optimal flowback distribution solution. • An empirical study using the shale gas data in Bradford County of Marcellus Shale. • Visualization of optimal flowback distribution solutions under different scenarios. • Transportation cost is a more important factor for reducing the cost. • Help the developers to cut the storage and transportation cost of reusing flowback.
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.
A Theoretical Study of Subsurface Drainage Model Simulation of ...
African Journals Online (AJOL)
A three-dimensional variable-density groundwater flow model, the SEAWAT model, was used to assess the influence of subsurface drain spacing, evapotranspiration and irrigation water quality on salt concentration at the base of the root zone, leaching and drainage in salt affected irrigated land. The study was carried out ...
The Interval Market Model in Mathematical Finance : Game Theoretic Methods
Bernhard, P.; Engwerda, J.C.; Roorda, B.; Schumacher, J.M.; Kolokoltsov, V.; Saint-Pierre, P.; Aubin, J.P.
2013-01-01
Toward the late 1990s, several research groups independently began developing new, related theories in mathematical finance. These theories did away with the standard stochastic geometric diffusion “Samuelson” market model (also known as the Black-Scholes model because it is used in that most famous
Experimental observations and theoretical models for beam-beam phenomena
International Nuclear Information System (INIS)
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 10 -10 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
Kolhatkar, Ashra; Keesey, Andrea; Bluman, Bob; Lynn, Brenna; Wilkinson, Tandi
2017-11-01
The challenges facing emergency medicine (EM) services in Canada reflect the limitations of the entire healthcare system. The emergency department (ED) is uniquely situated in the healthcare system such that shortcomings in hospital- and community-based services are often first revealed there. This is especially true in rural settings, where there are additional site-specific barriers to the provision of EM care. Existing studies look at the factors that influence rural EM physicians in isolation. This study uses a qualitative approach and generates a theoretical model that describes the complex interplay between major factors that influence the experience of rural EM physicians. Eight focus groups were conducted with 39 physicians from rural British Columbia, Canada. Semi-structured focus group protocols were designed to leverage the diversity of the focus groups, which included rural generalists, full-time EM practitioners, physicians from very small and remote communities, locums, international medical graduates, physicians new to practice, and physicians who no longer practice rural EM. Following the principles of grounded theory, interview probes were adjusted iteratively to reflect emerging findings. Transcripts were analysed to identify codes and major themes, which served as the basis for the theoretical model. The theoretical model reveals how the causal conditions (a lack of medical and human resources, and the isolation of rural communities due to topography, distance, and inclement weather) contribute to physicians' common experience of feeling fearful and under-supported at work. Two core phenomena emerge as important needs: supportive professional relationships, and healthcare system adaptability. Contextual factors such as remuneration and continuing medical education funding, and the intervening conditions of physicians' rural exposure during formative years, also have an effect. Physicians create innovative solutions to address the challenges that
International Nuclear Information System (INIS)
Barbu, A.
2008-01-01
Recent developments in multi-scale modelling, based on atomic scale calculations, are leading to a growing conviction that modelling will soon be used to design material components for nuclear reactors. In this article we discuss this assumption on the basis of the relationship between experimental studies and theoretical calculations of the microstructural evolution of materials under irradiation. In the first part of the paper, the available numerical models for long term microstructural evolutions are briefly reviewed. The experimental methods are presented in a second part. In the third part, several examples of fruitful relationships between modelling and experiments are discussed. The first example deals with the isochronal electrical resistivity recovery of electron irradiated ultra pure iron at 14 K, the second one is dedicated to the microstructural evolution of ferritic model alloy during continuous irradiation with 1 MeV electrons at large fluences, the third one is the modelling of He desorption of helium implanted iron, and the fourth example concerns the mechanisms of formation of solute rich clusters observed by 3-dimensional atom probe in irradiated pressure vessel steels of water pressurized nuclear reactors
Mesterton-Gibbons, Mike; Sherratt, Tom N
2016-04-07
While the first individuals to discover and maintain territories are generally respected as owners, under some conditions there may be ambiguity as to who got there first. Here we attempt to understand the evolutionary consequences of this ambiguity by developing a pair of game-theoretic models in which we explicitly consider rival residency-based claims to ownership. Following earlier qualitative explanations for residency effects, we assume that either the value of the territory (Model A) or an interloper׳s self-belief that it is the owner (Model B) increases with duration of residency. Model A clearly demonstrates that if the value of a territory increases to a resident over time, so should its motivation to fight in terms of the effort it invests in fighting. Indeed, only a small increase in territory value with residency duration can be sufficient for longer established residents to win disputes, even without any arbitrary convention or other form of priority effect. Likewise, Model B shows that the observed increase in fighting persistence with residency duration can be readily explained as a consequence of increasing confidence on behalf of the interloper that it is the rightful owner. Collectively, the models help to explain some general findings long observed by empiricists, and shed light on the nature of conflicts that can arise when individuals do not have complete information about rival claims to ownership. Copyright © 2016 Elsevier Ltd. All rights reserved.
Theoretical investigation of radical species formed from L-α-alanine under gamma-irradiation
International Nuclear Information System (INIS)
Simion, C.
2008-01-01
Gamma-irradiated L-α-alanine used in EPR-coupled dosimetry has a complex EPR spectrum at room temperature. Changing the temperature or other conditions of the irradiated samples leads to varied EPR spectrum, i.e., some components disappear and/or new ones are formed. We used both molecular mechanics (MM+) and semiempirical (AM1) methods to perform a theoretical investigation of the seven radical species that have been experimentally detected. We established their order of priority in the given simulation conditions (at 0 K, in vacuo). The formation stages advanced for these long-lived radical species were characterized by a theoretical determination of the reaction enthalpies. (author)
Under the spell of Landau when theoretical physics was shaping destinies
2013-01-01
This invaluable collection of memoirs and reviews on scientific activities of the most prominent theoretical physicists belonging to the Landau School - Landau, Anselm, Gribov, Zeldovich, Kirzhnits, Migdal, Ter-Martirosyan and Larkin - are being published in English for the first time. The main goal is to acquaint readers with the life and work of outstanding Soviet physicists who, to a large extent, shaped theoretical physics in the 1950s - 70s. Many intriguing details have remained unknown beyond the "Iron Curtain" which was dismantled only with the fall of the USSR.
A theoretical model for gas permeability in a composite membrane
International Nuclear Information System (INIS)
Serrano, D. A
2009-01-01
We present in this work an analytical expression for permeability in a two-layer composite membrane, which was derived assuming the same hypothesis as those of Adzumi model for permeability in a homogeneous membrane. Whereas in Adzumi model permeability shows a linear dependence on the mean pressure, our model for a composite membrane related permeability to pressure through a rather complex expression, which covers the whole range of flow, from molecular-Knudsen to viscous-Poiseuille regimes. The expression obtained for permeability contained information of membrane structural properties as pore size, porosity and thickness of each layer, as well as gas nature and operational conditions. Our two-layer-model expression turns into Adzumi formula when the structure of the layers approach to each other. [es
Theoretical tornado vortex model for nuclear plant design
International Nuclear Information System (INIS)
Sun, C.N.; Barnett, R.O.; Burdette, E.G.
1977-01-01
A simplified tornado vortex model is defined using fluid dynamics theory. Beginning with the Navier-Stokes equations of motion for an incompressible fluid and simpifying in a way consistent with a tornado wind field, develops the well-known cyclostrophic wind equation referred to by Hoecker and another equation which defines the tangential velocity profile. Together, they define a simplified tornado vertex model of which the Rankine and Hoecker vortices are special cases. Practical implications of the results obtained are discussed. (Auth.)
Design theoretic analysis of three system modeling frameworks.
Energy Technology Data Exchange (ETDEWEB)
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.
The protective action decision model: theoretical modifications and additional evidence.
Lindell, Michael K; Perry, Ronald W
2012-04-01
The Protective Action Decision Model (PADM) is a multistage model that is based on findings from research on people's responses to environmental hazards and disasters. The PADM integrates the processing of information derived from social and environmental cues with messages that social sources transmit through communication channels to those at risk. The PADM identifies three critical predecision processes (reception, attention, and comprehension of warnings or exposure, attention, and interpretation of environmental/social cues)--that precede all further processing. The revised model identifies three core perceptions--threat perceptions, protective action perceptions, and stakeholder perceptions--that form the basis for decisions about how to respond to an imminent or long-term threat. The outcome of the protective action decision-making process, together with situational facilitators and impediments, produces a behavioral response. In addition to describing the revised model and the research on which it is based, this article describes three applications (development of risk communication programs, evacuation modeling, and adoption of long-term hazard adjustments) and identifies some of the research needed to address unresolved issues. © 2011 Society for Risk Analysis.
A game-theoretical model of private power production
International Nuclear Information System (INIS)
Xing, W.; Wu, F.F.
2001-01-01
Private power production has sprung up all over the world. The build-operate-transfer (BOT) arrangement has emerged as one of the most important options for private power production, especially in developing countries with rapidly growing demand and financial shortages. Based on oligopoly theory, the paper proposes a Stackelberg game model between a BOT investor and an electric utility whereby they can negotiate a long-term energy contract. Asymmetric pricing schemes are taken into account such that a host utility purchases electricity from a BOT company at its ''avoided cost'', and sells its electricity to end users at its ''average cost''. Our Stackelberg game model is transferred into a two-level optimization problem, and then solved by an iterative algorithm. The game model is demonstrated by an illustrative example. (author)
Theoretical models in the development of advertising for food products
DEFF Research Database (Denmark)
Bech-Larsen, Tino; Stacey, Julia
2005-01-01
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...... apples. One proposal, which is based on the meansendchain model, tries to establish a connection between the vitamin and energy content of apples and the personal value: quality of life. The other one is made in the traditional fashion, ie without the use of theoreticalmodels. Its message is that apples...
Accidental naturalism: criticism of a theoretical model of socio-ecological legitimacy
Directory of Open Access Journals (Sweden)
Santiago M. Cruzada
2017-11-01
Full Text Available This article proposes the need for a theoretical review on the current epistemological assumption that establishes the dichotomy nature-society as a cornerstone of a broad worldview for western contexts. We will discuss the anthropological perspectives that assume that in these spaces, generically without nuances, social practice and ideas are not constructed in such a close relationship to the environment, falling under a belief that nature exists outside the human will. We will debate the naive ethnological essentialism that position naturalism as a central model of a socio-european worldview, characterized by dualistic patterns that have enabled monistic paradigms of socio-ecological relationships to be established at the same time, and in contrast to this, in other parts of the world.
High temperature electrolyzer based on solid oxide co-ionic electrolyte: A theoretical model
Energy Technology Data Exchange (ETDEWEB)
Demin, Anatoly; Gorbova, Elena [Institute of High Temperature Electrochemistry, 22 S. Kovalevskoy, 620219 Yekaterinburg (Russian Federation); Tsiakaras, Panagiotis [School of Engineering, Department of Mechanical Engineering, University of Thessaly, Pedion Areos, 383 34 Volos (Greece)
2007-09-19
In the present work a theoretical model of a solid oxide electrolyzer based on an electrolyte having both oxygen ion and proton conductivity is considered. The main parameters of the electrolytic process and an electrolyzer (distribution of gas components, electromotive forces and current densities along the electrolyzer channel, average values of electromotive forces and current densities) were calculated depending on a proton transport number and mode of the reactants' feeding (co- and counter-flow). The performed analysis demonstrates considerable influence of the mode of feeding on all parameters of the electrolyzer: operation under the counter-flow mode is preferable as regards the specific characteristics and uniformity of their distribution along the electrolyzer. It is shown that the electrolyser's specific characteristics increase with the increase of the proton transport number. (author)
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
A theoretical and empirical model for soil conservation using ...
African Journals Online (AJOL)
This paper illuminates the practice of indigenous soil conservation among Mamasani farmers in Fars province in Iran. Bos's decision making model was used as a conceptual framework for the study. A qualitative paradigm was used as research methodology. Qualitative techniques were: Mind Mapping, RRA ...
A theoretical Markov chain model for evaluating correctional ...
African Journals Online (AJOL)
In this paper a stochastic method is applied in the study of the long time effect of confinement in a correctional institution on the behaviour of a person with criminal tendencies. The approach used is Markov chain, which uses past history to predict the state of a system in the future. A model is developed for comparing the ...
An Alternative Theoretical Model for Economic Reforms in Africa ...
African Journals Online (AJOL)
This paper offers an alternative model for economic reforms in Africa. It proposes that Africa can still get on the pathway of sustained economic growth if economic reforms can focus on a key variable, namely, the price of non-tradables. Prices of non-tradables are generally less in Africa than in advanced economies, and the ...
A coordination theoretic model for three level supply chains using ...
Indian Academy of Sciences (India)
the contract renewal time, the supply chain nervousness can be reduced. A pricing model is formulated to address partnership expectations for a fair sharing of savings of the supply chain members. ...... the level of optimality and robustness of a given strategy (Terzi & Cavalieri 2004). Simulation may be used to capture ...
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…
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. © 2015 Society for Risk Analysis.
Game-Theoretic Models for Usage-based Maintenance Contract
Husniah, H.; Wangsaputra, R.; Cakravastia, A.; Iskandar, B. P.
2018-03-01
A usage-based maintenance contracts with coordination and non coordination between two parties is studied in this paper. The contract is applied to a dump truck operated in a mining industry. The situation under study is that an agent offers service contract to the owner of the truck after warranty ends. This contract has only a time limit but no usage limit. If the total usage per period exceeds the maximum usage allowed in the contract, then the owner will be charged an additional cost. In general, the agent (Original Equipment Manufacturer/OEM) provides a full coverage of maintenance, which includes PM and CM under the lease contract. The decision problem for the owner is to select the best option offered that fits to its requirement, and the decision problem for the agent is to find the optimal maintenance efforts for a given price of the service option offered. We first find the optimal decisions using coordination scheme and then with non coordination scheme for both parties.
Theoretical model of the early phases of an underground explosion
International Nuclear Information System (INIS)
Cameron, I.G.; Scorgie, G.C.
1970-01-01
Introduction In the early phases of the intense underground explosions contemplated in peaceful applications the rock near the explosive exhibits fluid behaviour; at great distances its behaviour can usefully be investigated in terms of linear elasticity; and at intermediate distances we think of a solid exhibiting various inelastic effects including cracking and tensile fracture. The present paper outlines a mathematical model that attempts to include in some degree the main features of this range of behaviour. A more detailed treatment than is given here, and its relationship to the work of others, is given in a paper by the authors. A computer program ATHENE has been written based on this model and its use is illustrated by examining some aspects of two types of explosions. One is a chemical explosion which eventually formed a crater and the other a nuclear explosion which remained wholly contained
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...
International Nuclear Information System (INIS)
Balagyra, V.S.; Ryabka, P.M.
1999-01-01
For measuring the charged particle energy calculations of mean square angles of electron beam multiple Coulomb scattering at output combined accelerator target were undertaken according to seven theoretical models. Mollier method showed the best agreement with experiments
Theoretical study (Lagrangian modeling) of turbulent particulate dispersion
Berlemont, A.; Grancher, M. S.; Desjonqueres, P.
A study aimed at improving the prediction and knowledge of two phase phenomena in a turbomachine is presented. A code to three dimensionally simulate particle dispersion, taking account of turbulent droplet evaporation, and which can be easily integrated into the DIAMANT code, is developed. Lagrangian modeling of particle dispersion is used. The influence of turbulence on evaporation appears to be non-negligible and must therefore be taken into account in droplet turbulent transfer problems.
Theoretical modeling of infrared spectra of twinned lead zirconate
Czech Academy of Sciences Publication Activity Database
Dočekalová, Zuzana; Pasciak, Marek; Hlinka, Jiří
2017-01-01
Roč. 90, č. 1 (2017), s. 17-23 ISSN 0141-1594 R&D Projects: GA ČR GA15-04121S Institutional support: RVO:68378271 Keywords : domains * IR spectroscopy * dielectric permittivity * lead zirconate * shell model * Born effective charge Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.060, year: 2016
Testing theoretical models of subdwarf B stars using multicolor photometry
Reed, Mike; Baran, Andrzej; Ostensen, Roy; O'Toole, Simon
2012-08-01
Pulsating stars allow a direct investigation of their structure and evolutionary history from the evaluation of pulsation modes. However, the observed pulsation frequencies must first be identified with spherical harmonics (modes). For subdwarfs B (sdB) stars, such identifications using white light photometry currently have significant limitations. We intend to use multicolor photometry to identify pulsation modes and constrain structure models. We propose to observe the pulsating sdB star PG0154+182 (BI Ari) with our multicolor instrument GT Cam. Our observations will be compared with perturbative atmospheric models (BRUCE/KYLIE) to identify the pulsation modes. This is part of our NSF grant to obtain seismic tools to test structure and evolution models; constraining stellar parameters including total mass, envelope mass, internal composition discontinuities and internal rotation. During winter/spring 2012, we were allocated three runs on the 2.1 m to collect multicolor data on other promising pulsating subdwarf B stars as part of this work. Those runs were very successful, prompting our continued proposals. In addition, we will obtain 3-color data using MAIA on the Mercator Telescope (using guaranteed institutional time).
Modeling postpartum depression in rats: theoretic and methodological issues
Ming, LI; Shinn-Yi, CHOU
2016-01-01
The postpartum period is when a host of changes occur at molecular, cellular, physiological and behavioral levels to prepare female humans for the challenge of maternity. Alteration or prevention of these normal adaptions is thought to contribute to disruptions of emotion regulation, motivation and cognitive abilities that underlie postpartum mental disorders, such as postpartum depression. Despite the high incidence of this disorder, and the detrimental consequences for both mother and child, its etiology and related neurobiological mechanisms remain poorly understood, partially due to the lack of appropriate animal models. In recent decades, there have been a number of attempts to model postpartum depression disorder in rats. In the present review, we first describe clinical symptoms of postpartum depression and discuss known risk factors, including both genetic and environmental factors. Thereafter, we discuss various rat models that have been developed to capture various aspects of this disorder and knowledge gained from such attempts. In doing so, we focus on the theories behind each attempt and the methods used to achieve their goals. Finally, we point out several understudied areas in this field and make suggestions for future directions. PMID:27469254
A Theoretical Model for the Associative Nature of Conference Participation.
Directory of Open Access Journals (Sweden)
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.
2015-01-01
among exposed teens . Of the exposed group, 2.5 percent reported having made a (first) suicide attempt during the 18 months of follow-up compared...Gatekeeper Training for Suicide Prevention A Theoretical Model and Review of the Empirical Literature Crystal Burnette, Rajeev Ramchand, Lynsay...REPORT TYPE 3. DATES COVERED 00-00-2015 to 00-00-2015 4. TITLE AND SUBTITLE Gatekeeper Training for Suicide Prevention: A Theoretical Model and
NOOP: A Domain-Theoretic Model of Nominally-Typed OOP
AbdelGawad, Moez; Cartwright, Robert
2018-01-01
The majority of industrial-strength object-oriented (OO) software is written using nominally-typed OO programming languages. Extant domain-theoretic models of OOP developed to analyze OO type systems miss, however, a crucial feature of these mainstream OO languages: nominality. This paper presents the construction of NOOP as the first domain-theoretic model of OOP that includes full class/type names information found in nominally-typed OOP. Inclusion of nominal information in objects of NOOP ...
4. Valorizations of Theoretical Models of Giftedness and Talent in Defining of Artistic Talent
Anghel Ionica Ona
2016-01-01
Artistic talent has been defined in various contexts and registers a variety of meanings, more or less operational. From the perspective of pedagogical intervention, it is imperative understanding artistic talent trough the theoretical models of giftedness and talent. So, the aim of the study is to realize a review of the most popular of the theoretical models of giftedness and talent, with identification of the place of artistic talent and the new meanings that artistic talent has in each on...
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.
Testing theoretical models of magnetic damping using an air track
Vidaurre, Ana; Riera, Jaime; Monsoriu, Juan A.; Gimenez, Marcos H.
2007-01-01
Magnetic braking is a long-established application of Lenz's law. A rigorous analysis of the laws governing this problem involves solving Maxwell's equations in a time-dependent situation. Approximate models have been developed to describe different experiences related to this phenomenon. In this paper we present a new method for the analysis of the magnetic braking using a magnet fixed to the glider of an air track. The forces acting on the glider, a result of the eddy currents, can be easil...
A theoretical study of a nickel SPND using Warren's model
International Nuclear Information System (INIS)
Mahant, A.K.; Rao, P.S.; Misra, S.C.
1998-01-01
Various parameters for a nickel SPND viz. neutron and gamma sensitivity, their dependence on detector dimensions, effect of activity build up during irradiation in the reactor on neutron sensitivity and burn up have been calculated using an analytical model by Warren and Shah. The results show that the main component of neutron sensitivity is due to neutron-induced capture gamma rays (99.93%). Delayed β signal is negligible and signal due to external gamma rays constitute about 0.06%. Low gamma sensitivity to external gamma rays, negligible activity buildup and low burn up rate make it a very promising prompt SPND for power reactors. (orig.)
Polarimetric Signatures of Sea Ice. Part 1; Theoretical Model
Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Drinkwater, M. R.
1995-01-01
Physical, structural, and electromagnetic properties and interrelating processes in sea ice are used to develop a composite model for polarimetric backscattering signatures of sea ice. Physical properties of sea ice constituents such as ice, brine, air, and salt are presented in terms of their effects on electromagnetic wave interactions. Sea ice structure and geometry of scatterers are related to wave propagation, attenuation, and scattering. Temperature and salinity, which are determining factors for the thermodynamic phase distribution in sea ice, are consistently used to derive both effective permittivities and polarimetric scattering coefficients. Polarimetric signatures of sea ice depend on crystal sizes and brine volumes, which are affected by ice growth rates. Desalination by brine expulsion, drainage, or other mechanisms modifies wave penetration and scattering. Sea ice signatures are further complicated by surface conditions such as rough interfaces, hummocks, snow cover, brine skim, or slush layer. Based on the same set of geophysical parameters characterizing sea ice, a composite model is developed to calculate effective permittivities and backscattering covariance matrices at microwave frequencies for interpretation of sea ice polarimetric signatures.
Polarimetric signatures of sea ice. 1: Theoretical model
Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Drinkwater, M. R.
1995-01-01
Physical, structral, and electromagnetic properties and interrelating processes in sea ice are used to develop a composite model for polarimetric backscattering signatures of sea ice. Physical properties of sea ice constituents such as ice, brine, air, and salt are presented in terms of their effects on electromagnetic wave interactions. Sea ice structure and geometry of scatterers are related to wave propagation, attenuation, and scattering. Temperature and salinity, which are determining factors for the thermodynamic phase distribution in sea ice, are consistently used to derive both effective permittivities and polarimetric scattering coefficients. Polarmetric signatures of sea ice depend on crystal sizes and brine volumes, which are affected by ice growth rates. Desalination by brine expulsion, drainage, or other mechanisms modifies wave penetration and scattering. Sea ice signatures are further complicated by surface conditions such as rough interfaces, hummocks, snow cover, brine skim, or slush layer. Based on the same set of geophysical parameters characterizing sea ice, a composite model is developed to calculate effective permittivities and backscattering covariance matrices at microwave frequencies to interpretation of sea ice polarimetric signatures.
Theoretical modeling of molar volume and thermal expansion
Energy Technology Data Exchange (ETDEWEB)
Lu Xiaogang [Department of Materials Science and Engineering, Royal Institute of Technology, 100 44 Stockholm (Sweden)]. E-mail: gang@mse.kth.se; Selleby, Malin [Department of Materials Science and Engineering, Royal Institute of Technology, 100 44 Stockholm (Sweden); Sundman, Bo [Department of Materials Science and Engineering, Royal Institute of Technology, 100 44 Stockholm (Sweden)
2005-05-15
The molar volumes and thermal expansions of transition cubic metals were studied by means of the Calphad approach and the Debye-Grueneisen model. Experimental data were collected and assessed using Calphad procedures, and consistent results were obtained which give the best description of all experimental data. In order to put the prediction of the thermodynamic properties of metastable phases on a sound physical basis, the Debye-Grueneisen model was chosen to account for the vibrational contribution and calculate the coefficients of linear thermal expansion (CLEs) of stable cubic metals. Two approximations for Grueneisen parameter {gamma}, i.e. Slater's and Dugdale and MacDonald's expressions were adopted. A modified calculation scheme, first proposed by Wang et al., was derived in a straightforward way and used to evaluate the Debye temperature from ab initio electronic total-energy calculations at T = 0 K. The thermal electronic contribution to CLE was also evaluated from the electronic density of states. The calculated total CLEs were compared with those from the Calphad assessments. A satisfactory agreement is reached.
Theoretical modeling of molar volume and thermal expansion
International Nuclear Information System (INIS)
Lu Xiaogang; Selleby, Malin; Sundman, Bo
2005-01-01
The molar volumes and thermal expansions of transition cubic metals were studied by means of the Calphad approach and the Debye-Grueneisen model. Experimental data were collected and assessed using Calphad procedures, and consistent results were obtained which give the best description of all experimental data. In order to put the prediction of the thermodynamic properties of metastable phases on a sound physical basis, the Debye-Grueneisen model was chosen to account for the vibrational contribution and calculate the coefficients of linear thermal expansion (CLEs) of stable cubic metals. Two approximations for Grueneisen parameter γ, i.e. Slater's and Dugdale and MacDonald's expressions were adopted. A modified calculation scheme, first proposed by Wang et al., was derived in a straightforward way and used to evaluate the Debye temperature from ab initio electronic total-energy calculations at T = 0 K. The thermal electronic contribution to CLE was also evaluated from the electronic density of states. The calculated total CLEs were compared with those from the Calphad assessments. A satisfactory agreement is reached
A theoretical quantitative model for evolution of cancer chemotherapy resistance
Directory of Open Access Journals (Sweden)
Gatenby Robert A
2010-04-01
Full Text Available Abstract Background Disseminated cancer remains a nearly uniformly fatal disease. While a number of effective chemotherapies are available, tumors inevitably evolve resistance to these drugs ultimately resulting in treatment failure and cancer progression. Causes for chemotherapy failure in cancer treatment reside in multiple levels: poor vascularization, hypoxia, intratumoral high interstitial fluid pressure, and phenotypic resistance to drug-induced toxicity through upregulated xenobiotic metabolism or DNA repair mechanisms and silencing of apoptotic pathways. We propose that in order to understand the evolutionary dynamics that allow tumors to develop chemoresistance, a comprehensive quantitative model must be used to describe the interactions of cell resistance mechanisms and tumor microenvironment during chemotherapy. Ultimately, the purpose of this model is to identify the best strategies to treat different types of tumor (tumor microenvironment, genetic/phenotypic tumor heterogeneity, tumor growth rate, etc.. We predict that the most promising strategies are those that are both cytotoxic and apply a selective pressure for a phenotype that is less fit than that of the original cancer population. This strategy, known as double bind, is different from the selection process imposed by standard chemotherapy, which tends to produce a resistant population that simply upregulates xenobiotic metabolism. In order to achieve this goal we propose to simulate different tumor progression and therapy strategies (chemotherapy and glucose restriction targeting stabilization of tumor size and minimization of chemoresistance. Results This work confirms the prediction of previous mathematical models and simulations that suggested that administration of chemotherapy with the goal of tumor stabilization instead of eradication would yield better results (longer subject survival than the use of maximum tolerated doses. Our simulations also indicate that the
Theoretical modelling of hot gas ingestion through turbine rim seals
Directory of Open Access Journals (Sweden)
J. Michael Owen
2012-12-01
The nozzle guide vanes create three-dimensional (3D variations in the distribution of pressure in the mainstream annulus and the turbine blades create unsteady effects. Computational fluid dynamics (CFD is both time-consuming and expensive for these 3D unsteady flows, and engine designers tend to use correlations or simple models to predict ingress. This paper describes the application of simple ‘orifice models’, the analytical solutions of which can be used to calculate the sealing effectiveness of turbine rim seals. The solutions agree well with available data for externally-induced ingress, where the effects of rotation are negligible, for rotationally-induced ingress, where the effects of the external flow are small, and for combined ingress, where the effects of both external flow and rotation are significant.
A Theoretical Design for Learning Model Addressing the Networked Society
DEFF Research Database (Denmark)
Nielsen, Janni; Levinsen, Karin Tweddell; Sørensen, Birgitte Holm
2010-01-01
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....... The context for the experiment is MIL's course on Interaction Design. The orchestration is operationalized as a 4-hour script that builds on classic role-play designed as an open ended explorative task. The script of the teams' tasks is designed to facilitate the teams' ongoing negotiation and structuring...... which enables students to develop Networked Society competencies and maintain progression in the learning process also during the online periods. Additionally we suggest that our model contributes to the innovation of a networked society's design for learning....
Theoretical model of fast electron emission from surfaces
Energy Technology Data Exchange (ETDEWEB)
Reinhold, C.; Burgdoerfer, J. [Univ. of Tennessee, Knoxville, TN (United States)]|[Oak Ridge National Laboratory, TN (United States)
1993-05-01
Electron emission in glancing-angle ion-surface collisions has become a focus of ion-surface interactions. Electron spectra can provide detailed information on the above surface neutralization dynamics of multiply charged ions, the electronic structure of the surface (surface density of states), and the long-ranged image interactions near the surface. Recent experiments have found that the convoy peak, well known from ion-atom and ion-solid collisions, is dramatically altered. The peak is broadened and shifted in energy which has been attributed to dynamical image interactions. We present a microscopic model for the emission of fast electrons in glancing-angle surface collisions. A classical trajectory Monte Carlo approach is utilized to calculate the evolution of electrons in the presence of their self image, the projectile Coulomb field and the image potential induced by the projectile. The excitation of collective surface modes is also incorporated.
RADIONUCLIDE TRANSPORT MODELS UNDER AMBIENT CONDITIONS
Energy Technology Data Exchange (ETDEWEB)
S. Magnuson
2004-11-01
The purpose of this model report is to document the unsaturated zone (UZ) radionuclide transport model, which evaluates, by means of three-dimensional numerical models, the transport of radioactive solutes and colloids in the UZ, under ambient conditions, from the repository horizon to the water table at Yucca Mountain, Nevada.
Directory of Open Access Journals (Sweden)
Yingwu Zhou
2015-01-01
Full Text Available Sulfate corrosion is one of the most important factors responsible for the performance degradation of concrete materials. In this paper, an accelerated corrosion by a sulfate solution in a dry-wet cycle was introduced to simulate the external sulfate corrosion environment. The deterioration trend of concrete strength and development law of sulfate-induced concrete corrosion depth under sulfate attacks were experimentally studied. The damaged concrete section is simply but reasonably divided into uncorroded and corroded layers and the two layers can be demarcated by the sulfate corrosion depth of concrete. The accelerated corrosion test results indicated that the strength degradation of concrete by sulfate attack had a significant relation with the corrosion depth. Consequently, this paper aims to reveal such relation and thus model the strength degradation law. A large amount of experimental data has finally verified the validity and applicability of the models, and a theoretical basis is thus provided for the strength degradation prediction and the residual life assessment of in-service concrete structures under sulfate attacks.
Fieselmann, Andreas; Kowarschik, Markus; Ganguly, Arundhuti; Hornegger, Joachim; Fahrig, Rebecca
2011-01-01
Deconvolution-based analysis of CT and MR brain perfusion data is widely used in clinical practice and it is still a topic of ongoing research activities. In this paper, we present a comprehensive derivation and explanation of the underlying physiological model for intravascular tracer systems. We also discuss practical details that are needed to properly implement algorithms for perfusion analysis. Our description of the practical computer implementation is focused on the most frequently employed algebraic deconvolution methods based on the singular value decomposition. In particular, we further discuss the need for regularization in order to obtain physiologically reasonable results. We include an overview of relevant preprocessing steps and provide numerous references to the literature. We cover both CT and MR brain perfusion imaging in this paper because they share many common aspects. The combination of both the theoretical as well as the practical aspects of perfusion analysis explicitly emphasizes the simplifications to the underlying physiological model that are necessary in order to apply it to measured data acquired with current CT and MR scanners. PMID:21904538
Fieselmann, Andreas; Kowarschik, Markus; Ganguly, Arundhuti; Hornegger, Joachim; Fahrig, Rebecca
2011-01-01
Deconvolution-based analysis of CT and MR brain perfusion data is widely used in clinical practice and it is still a topic of ongoing research activities. In this paper, we present a comprehensive derivation and explanation of the underlying physiological model for intravascular tracer systems. We also discuss practical details that are needed to properly implement algorithms for perfusion analysis. Our description of the practical computer implementation is focused on the most frequently employed algebraic deconvolution methods based on the singular value decomposition. In particular, we further discuss the need for regularization in order to obtain physiologically reasonable results. We include an overview of relevant preprocessing steps and provide numerous references to the literature. We cover both CT and MR brain perfusion imaging in this paper because they share many common aspects. The combination of both the theoretical as well as the practical aspects of perfusion analysis explicitly emphasizes the simplifications to the underlying physiological model that are necessary in order to apply it to measured data acquired with current CT and MR scanners.
International Nuclear Information System (INIS)
Anon.
1975-01-01
Work in theoretical chemistry was organized under the following topics: scattering theory and dynamics (elastic scattering of the rare gas hydrides, inelastic scattering in Li + H 2 , statistical theory for bimolecular collisions, model study of dissociative scattering, comparative study of elastic scattering computational methods), studies of atmospheric diatomic and triatomic species, structure and spectra of diatomic molecules, the evaluation of van der Waals forces, potential energy surfaces and structure and dynamics, calculation of molecular polarizabilities, and development of theoretical techniques and computing systems. Spectroscopic parameters are tabulated for NO 2 , N 2 O, H 2 O + , VH, and NH. Self-consistent-field wave functions were computed for He 2 in two-center and three-center bases. Rare gas hydride intermolecular potentials are shown. (9 figures, 14 tables) (U.S.)
Theoretical and Numerical Modeling of Acoustic Metamaterials for Aeroacoustic Applications
Directory of Open Access Journals (Sweden)
Umberto Iemma
2016-05-01
Full Text Available The advent, during the first decade of the 21st century, of the concept of acoustic metamaterial has disclosed an incredible potential of development for breakthrough technologies. Unfortunately, the extension of the same concepts to aeroacoustics has turned out to be not a trivial task, because of the different structure of the governing equations, characterized by the presence of the background aerodynamic convection. Some of the approaches recently introduced to circumvent the problem are biased by a fundamental assumption that makes the actual realization of devices extremely unlikely: the metamaterial should guarantee an adapted background aerodynamic convection in order to modify suitably the acoustic field and obtain the desired effect, thus implying the porosity of the cloaking device. In the present paper, we propose an interpretation of the metamaterial design that removes this unlikely assumption, focusing on the identification of an aerodynamically-impermeable metamaterial capable of reproducing the surface impedance profile required to achieve the desired scattering abatement. The attention is focused on a moving obstacle impinged by an acoustic perturbation induced by a co-moving source. The problem is written in a frame of reference rigidly connected to the moving object to couple the convective wave equation in the hosting medium with the inertially-anisotropic wave operator within the cloak. The problem is recast in an integral form and numerically solved through a boundary-field element method. The matching of the local wave vector is used to derive a convective design of the metamaterial applicable to the specific problem analyzed. Preliminary numerical results obtained under the simplifying assumption of a uniform aerodynamic flow reveal a considerable enhancement of the masking capability of the convected design. The numerical method developed shows a remarkable computational efficiency, completing a simulation of the entire
VALIDATION OF THEORETICAL MODEL FOR DECISION MAKING ABOUT E-LEARNING IMPLEMENTATION
Directory of Open Access Journals (Sweden)
Nina Begičević
2006-12-01
Full Text Available In the paper the possibility to use mathematical models and statistical techniques in strategic planning and decision making about e-learning is presented. Strategic planning and decision making has been covered as consisting of four phases: (1 intelligence, (2 design, (3 choice and (4 implementation. Each of the phases will be described in this paper, but the accent will be put on the statistical evaluation of the results of the questionnaire which was based on the developed theoretical model for decision making about e-learning implementation in the higher education sector. In general, the main objectives of this paper are: (1 validation of the first theoretical model for decision making about e-learning implementation in the higher education sector, by means of factor analysis and (2 reduction of a large number of variables to a smaller number of factors, i.e. designing the improved theoretical model, for modelling purposes (developing AHP & ANP models.
Description of group-theoretical model of developed turbulence
International Nuclear Information System (INIS)
Saveliev, V L; Gorokhovski, M A
2008-01-01
We propose to associate the phenomenon of stationary turbulence with the special self-similar solutions of the Euler equations. These solutions represent the linear superposition of eigenfields of spatial symmetry subgroup generators and imply their dependence on time through the parameter of the symmetry transformation only. From this model, it follows that for developed turbulent process, changing the scale of averaging (filtering) of the velocity field is equivalent to composition of scaling, translation and rotation transformations. We call this property a renormalization-group invariance of filtered turbulent fields. The renormalization group invariance provides an opportunity to transform the averaged Navier-Stokes equation over a small scale (inner threshold of the turbulence) to larger scales by simple scaling. From the methodological point of view, it is significant to note that the turbulent viscosity term appeared not as a result of averaging of the nonlinear term in the Navier-Stokes equation, but from the molecular viscosity term with the help of renormalization group transformation.
Description of group-theoretical model of developed turbulence
Energy Technology Data Exchange (ETDEWEB)
Saveliev, V L [Institute of Ionosphere, Almaty 050020 (Kazakhstan); Gorokhovski, M A [Laboratoire de Mecanique des Fluides et Acoustique, Ecole Centrale de Lyon, 36, Avenue Guy de Collongues, F69134 Ecully-Cedex (France)], E-mail: saveliev@topmail.kz, E-mail: mikhael.gorokhovski@ec-lyon.fr
2008-12-15
We propose to associate the phenomenon of stationary turbulence with the special self-similar solutions of the Euler equations. These solutions represent the linear superposition of eigenfields of spatial symmetry subgroup generators and imply their dependence on time through the parameter of the symmetry transformation only. From this model, it follows that for developed turbulent process, changing the scale of averaging (filtering) of the velocity field is equivalent to composition of scaling, translation and rotation transformations. We call this property a renormalization-group invariance of filtered turbulent fields. The renormalization group invariance provides an opportunity to transform the averaged Navier-Stokes equation over a small scale (inner threshold of the turbulence) to larger scales by simple scaling. From the methodological point of view, it is significant to note that the turbulent viscosity term appeared not as a result of averaging of the nonlinear term in the Navier-Stokes equation, but from the molecular viscosity term with the help of renormalization group transformation.
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
THEORETICAL FLOW MODEL THROUGH A CENTRIFUGAL PUMP USED FOR WATER SUPPLY IN AGRICULTURE IRRIGATION
Directory of Open Access Journals (Sweden)
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.
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
Stress fluctuations in fracture networks from theoretical and numerical models
Davy, P.; Darcel, C.; Mas Ivars, D.; Le Goc, R.
2017-12-01
We analyze the spatial fluctuations of stress in a simple tridimensional model constituted by a population of disc-shaped fractures embedded in an elastic matrix with uniform and isotropic properties. The fluctuations arise from the classical stress enhancement at fracture tips and stress shadowing around fracture centers that are amplified or decreased by the interactions between close-by fractures. The distribution of local stresses is calculated at the elementary mesh scale with the 3DEC numerical program based on the distinct element method. As expected, the stress distributions vary with fracture density, the larger is the density, the wider is the distribution. For freely slipping fractures, it is mainly controlled by the percolation parameter p (i.e., the total volume of spheres surrounding fractures). For stresses smaller than the remote deviatoric stress, the distribution depends only on for the range of density that has been studied. For large stresses, the distribution decreases exponentially when increasing stress, with a characteristic stress that increases with entailing a widening of the stress distribution. We extend the analysis to fractures with plane resistance defined by an elastic shear stiffness ks and a slip Coulomb threshold. A consequence of the fracture plane resistance is to lower the stress perturbation in the surrounding matrix by a factor that depends on the ratio between ks and a fracture-matrix stiffness km mainly dependent on the ratio between Young modulus and fracture size. km is also the ratio between the remote shear stress and the displacement across the fracture plane in the case of freely slipping fractures. A complete analytical derivation of the expressions of the stress perturbations and of the fracture displacements is obtained and checked with numerical simulations. In the limit ks >> km, the stress perturbation tends to 0 and the stress state is spatially uniform. The analysis allows us to quantify the intensity of the
International Nuclear Information System (INIS)
Tong Yunxian; Wang Wenran
1992-03-01
The mass flowrate and steam quality measuring of two phase flowrate is an essential issue in the tests of loss-of-coolant accident (LOCA). The spatial stochastic distribution of phase concentration would cause a differential pressure noise when two phase flow is crossing a throttling set. Under the assumption of that the variance of disperse phase concentration is proportional to its mean phase concentration and by using the separated flow model of two phase flow, it has demonstrated that the variance of noise of differential pressure square root is approximately proportional to the flowrate of disperse phase. Thus, a theoretical model for measuring mass flowrate and quality of two phase flow by noise measurement is developed. It indicates that there is a possibility to measure two phase flowrate and steam quality by using the simple theoretical model and a single throttling set
DEFF Research Database (Denmark)
Nie, Jinzhe; Li, Zan; Hu, Wenju
2017-01-01
purification aimed at improving indoor air quality and reducing building energy consumption. The heat and moisture transfer in adsorption desiccant rotor was theoretical modelled with one-dimensional partial differential equations. The theoretical model was validated with experimental measurements......Taking the integrated gaseous contaminants and moisture adsorption potential of desiccant material, a new heat pump assisted solid desiccant cooling system (HP-SDC) was proposed based on the combination of desiccant rotor with heat pump. The HP-SDC was designed for dehumidification, cooling and air......, and the results showed the model could be used to predict the heat and moisture transfer in desiccant rotor. The air thermal conditioning process and energy consumption of HP-SDC was then experimental measured under varied outdoor thermal environments. Results showed that compared to conventional ventilation...
International Nuclear Information System (INIS)
Wietze, L.; Linderhof, V.; Kuik, O.; Kemfert, C.; Oestling, R.; Heinzow, T.
2006-10-01
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 Northwestern European countries, namely Belgium, Denmark, Finland, France, Germany, The Netherlands, Norway, and Sweden. Different market structures are compared, depending on the ability of firms to exercise market power, ranging from perfect competition without market power to strategic competition where large firms exercise market power. In addition, a market power reduction policy is studied where the near-monopolies in France and Belgium are demerged into smaller firms. To analyse environmental impacts, a fixed greenhouse gas emission reduction target is introduced under different market structures. The results indicate that the effects of liberalisation depend on the resulting market structure, but that a reduction in market power of large producers may be beneficial for both the consumer (i.e. lower prices) and the environment (i.e. lower greenhouse gas permit price and lower acidifying and smog emissions)
International Nuclear Information System (INIS)
Demichev, A.; Kryukov, A.; Rodionov, A.
2002-01-01
We propose an XML-based standard for formulation of field theoretical models. The goal of creation of such a standard is to provide a way for an unambiguous exchange and cross-checking of results of computer calculations in high energy physics. At the moment, the suggested standard implies that models under consideration are of the SM or MSSM type (i.e., they are just SM or MSSM, their submodels, smooth modifications or straightforward generalizations). (author)
Theoretical analysis of transcranial magneto-acoustical stimulation with Hodgkin–Huxley neuron model
Directory of Open Access Journals (Sweden)
Yi eYuan
2016-04-01
Full Text Available Transcranial magneto-acoustical stimulation (TMAS is a novel stimulation technology in which an ultrasonic wave within a magnetostatic field generates an electric current in an area of interest in the brain to modulate neuronal activities. As a key part of the neural network, neurons transmit information in the nervous system. However, the effect of TMAS on the neuronal firing rhythm remains unknown. To address this problem, we investigated the stimulatory mechanism of TMAS on neurons with a Hodgkin-Huxley neuron model. The simulation results indicate that the magnetostatic field intensity and ultrasonic power can affect the amplitude and interspike interval of neuronal action potential under continuous wave ultrasound. The simulation results also show that the ultrasonic power, duty cycle and repetition frequency can alter the firing rhythm of neural action potential under pulsed ultrasound. This study can help to reveal and explain the biological mechanism of TMAS and to provide a theoretical basis for TMAS in the treatment or rehabilitation of neuropsychiatric disorders.
Liang, Fuyou; Guan, Debao; Alastruey, Jordi
2018-03-01
Hypertension is a well-documented predictive factor for cardiovascular events. Clinical studies have extensively demonstrated the differential hemodynamic consequences of various antihypertensive drugs, but failed to clearly elucidate the underlying mechanisms due to the difficulty in performing a quantitative deterministic analysis based on clinical data that carry confounding information stemming from interpatient differences and the nonlinearity of cardiovascular hemodynamics. In the present study, a multiscale model of the cardiovascular system was developed to quantitatively investigate the relationships between hemodynamic variables and cardiovascular properties under hypertensive conditions, aiming to establish a theoretical basis for assisting in the interpretation of clinical observations or optimization of therapy. Results demonstrated that heart period, central arterial stiffness, and arteriolar radius were the major determinant factors for blood pressures and flow pulsatility indices both in large arteries and in the microcirculation. These factors differed in the degree and the way in which they affect hemodynamic variables due to their differential effects on wave reflections in the vascular system. In particular, it was found that the hemodynamic effects of varying arteriolar radius were considerably influenced by the state of central arterial stiffness, and vice versa, which implied the potential of optimizing antihypertensive treatment by selecting proper drugs based on patient-specific cardiovascular conditions. When analyzed in relation to clinical observations, the simulated results provided mechanistic explanations for the beneficial pressure-lowering effects of vasodilators as compared to β-blockers, and highlighted the significance of monitoring and normalizing arterial stiffness in the treatment of hypertension.
Radionuclide Transport Models Under Ambient Conditions
Energy Technology Data Exchange (ETDEWEB)
G. Moridis; Q. Hu
2001-12-20
The purpose of Revision 00 of this Analysis/Model Report (AMR) is to evaluate (by means of 2-D semianalytical and 3-D numerical models) the transport of radioactive solutes and colloids in the unsaturated zone (UZ) under ambient conditions from the potential repository horizon to the water table at Yucca Mountain (YM), Nevada.
Radionuclide Transport Models Under Ambient Conditions
International Nuclear Information System (INIS)
Moridis, G.; Hu, Q.
2001-01-01
The purpose of Revision 00 of this Analysis/Model Report (AMR) is to evaluate (by means of 2-D semianalytical and 3-D numerical models) the transport of radioactive solutes and colloids in the unsaturated zone (UZ) under ambient conditions from the potential repository horizon to the water table at Yucca Mountain (YM), Nevada
Scholz, Stefan; Graf von der Schulenburg, Johann-Matthias; Greiner, Wolfgang
2015-11-17
Regional differences in physician supply can be found in many health care systems, regardless of their organizational and financial structure. A theoretical model is developed for the physicians' decision on office allocation, covering demand-side factors and a consumption time function. To test the propositions following the theoretical model, generalized linear models were estimated to explain differences in 412 German districts. Various factors found in the literature were included to control for physicians' regional preferences. Evidence in favor of the first three propositions of the theoretical model could be found. Specialists show a stronger association to higher populated districts than GPs. Although indicators for regional preferences are significantly correlated with physician density, their coefficients are not as high as population density. If regional disparities should be addressed by political actions, the focus should be to counteract those parameters representing physicians' preferences in over- and undersupplied regions.
Nicassio, Perry M.
1985-01-01
Summarizes clinical and research literature on Southeast Asian refugees' adjustment in the United States and proposes the adoption of theoretical models that may help explain individual differences. Reports that acculturation, learned helplessness, and stress management models appear to aid the conceptualizing of refugee problems and provide a…
International Nuclear Information System (INIS)
Lind, M.
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)
D. Todd Jones-Farrand; Todd M. Fearer; Wayne E. Thogmartin; Frank R. Thompson; Mark D. Nelson; John M. Tirpak
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...
A new theoretical model of the quasistatic single-fiber pullout problem: Analysis of stress field
DEFF Research Database (Denmark)
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...... solution. © 2013 Elsevier Ltd. All rights reserved....
Energy Technology Data Exchange (ETDEWEB)
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)
Hsieh, Pei-Hsuan; Sullivan, Jeremy R.; Sass, Daniel A.; Guerra, Norma S.
2012-01-01
Research has identified factors associated with academic success by evaluating relations among psychological and academic variables, although few studies have examined theoretical models to understand the complex links. This study used structural equation modeling to investigate whether the relation between test anxiety and final course grades was…
Energy Technology Data Exchange (ETDEWEB)
Bakry, A. [King Abdulaziz University, 80203, Department of Physics, Faculty of Science (Saudi Arabia); Abdulrhmann, S. [Jazan University, 114, Department of Physics, Faculty of Sciences (Saudi Arabia); Ahmed, M., E-mail: mostafa.farghal@mu.edu.eg [King Abdulaziz University, 80203, Department of Physics, Faculty of Science (Saudi Arabia)
2016-06-15
We theoretically model the dynamics of semiconductor lasers subject to the double-reflector feedback. The proposed model is a new modification of the time-delay rate equations of semiconductor lasers under the optical feedback to account for this type of the double-reflector feedback. We examine the influence of adding the second reflector to dynamical states induced by the single-reflector feedback: periodic oscillations, period doubling, and chaos. Regimes of both short and long external cavities are considered. The present analyses are done using the bifurcation diagram, temporal trajectory, phase portrait, and fast Fourier transform of the laser intensity. We show that adding the second reflector attracts the periodic and perioddoubling oscillations, and chaos induced by the first reflector to a route-to-continuous-wave operation. During this operation, the periodic-oscillation frequency increases with strengthening the optical feedback. We show that the chaos induced by the double-reflector feedback is more irregular than that induced by the single-reflector feedback. The power spectrum of this chaos state does not reflect information on the geometry of the optical system, which then has potential for use in chaotic (secure) optical data encryption.
Expectancy-Violation and Information-Theoretic Models of Melodic Complexity
Directory of Open Access Journals (Sweden)
Tuomas Eerola
2016-07-01
Full Text Available The present study assesses two types of models for melodic complexity: one based on expectancy violations and the other one related to an information-theoretic account of redundancy in music. Seven different datasets spanning artificial sequences, folk and pop songs were used to refine and assess the models. The refinement eliminated unnecessary components from both types of models. The final analysis pitted three variants of the two model types against each other and could explain from 46-74% of the variance in the ratings across the datasets. The most parsimonious models were identified with an information-theoretic criterion. This suggested that the simplified expectancy-violation models were the most efficient for these sets of data. However, the differences between all optimized models were subtle in terms both of performance and simplicity.
Directory of Open Access Journals (Sweden)
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.
Jennings, Karen M
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.
Directory of Open Access Journals (Sweden)
Liu Jie
2013-01-01
Full Text Available Groundwater is a main natural factor impacting the subgrade structure, and it plays a significant role in the stability of the subgrade. In this paper, the analytical solution of the subgrade moisture variations considering groundwater fluctuations is derived based on Richards’ equation. Laboratory subgrade model is built, and three working cases are performed in the model to study the capillary action of groundwater at different water tables. Two types of antidrainage materials are employed in the subgrade model, and their anti-drainage effects are discussed. Moreover, numerical calculation is conducted on the basis of subgrade model, and the calculate results are compared with the experimental measurements. The study results are shown. The agreement between the numerical and the experimental results is good. Capillary action is obvious when the groundwater table is rising. As the groundwater table is falling, the moisture decreases in the position of the subgrade near the water table and has no variations in the subgrade where far above the table. The anti-drainage effect of the sand cushion is associated with its thickness and material properties. New waterproofing and drainage material can prevent groundwater entering the subgrade effectively, and its anti-drainage effect is good.
Thijssen, J.J.J.
2003-01-01
The rationality assumption has been the center of neo-classical economics for more than half a century now. In recent years much research has focussed on models of bounded rationality. In this thesis it is argued that both full and bounded rationality can be used for different kind of problems. In
A game-theoretical model for selecting a site of non-preferred waste facilities
International Nuclear Information System (INIS)
Kim, Seong Ho; Kim, Tae Woon
2006-01-01
In the present work, a game-theoretic model (GTM) as a tool of conflict analysis is proposed for multiplayer multicriteria decision-making problems in a conflict situation. The developed GTM is used for obtaining the most possible resolutions in the conflict among multiple decision makers. The GTM is based on directed graph structure and solution concepts. To demonstrate the performance of the GTM, using a numerical example, the GTM is applied to an environmental conflict problem, especially a non-preferred waste disposal siting conflict available in the literature. It is found that with GTM the states in equilibrium can be recognized. The conflict under consideration is to select a site of non-preferred waste facilities. The government is to choose a site of installation for users of a toxic waste disposal facility. A certain time-point of interest is a period of time to select one of candidate sites that completely meet regular criteria of governmental body in charge of permitting a facility site. The facility siting conflict among multiple players (i.e., decision-makers, DMs) of concern is viewed as a multiple player-multiple criteria (MPMC) domain. For instance, three possible sites (i.e., site A, site B, and site C) to be selected by multiple players are characterized by the building cost, accessibility, and proximity to the residential area. Concerning the site A, the installation of a facility is not expensive, the accessible to a facility is easy, and the site A is located very near a residential area. Concerning site B, the facility is expensive to build, the facility is easily accessible, and the site is located near the residential area. Concerning site C, the installation cost is expensive, the accessibility is difficult, and the location of site is far from the residential area. In simple models, three main groups of players could be considered to be the government, users, and local residents. The government is to play a role as one of proponents or
International Nuclear Information System (INIS)
Woods, D.D.; Roth, E.M.
1986-01-01
This paper reviews the major theoretical literatures that are relevant to modeling human cognitive activities important to nuclear power plant safety. The traditions considered include control theory, communication theory, statistical decision theory, information processing models and symbolic processing models. The review reveals a gradual convergence towards models that incorporate elements from multiple traditions. Models from the control theory tradition have gradually evolved to include rich knowledge representations borrowed from the symbolic processing work. At the same time theorists in the symbolic processing tradition are beginning to grapple with some of the critical issues involved in modeling complex real world domain
Theoretical-empirical model of the steam-water cycle of the power unit
Directory of Open Access Journals (Sweden)
Grzegorz Szapajko
2010-06-01
Full Text Available The diagnostics of the energy conversion systems’ operation is realised as a result of collecting, processing, evaluatingand analysing the measurement signals. The result of the analysis is the determination of the process state. It requires a usageof the thermal processes models. Construction of the analytical model with the auxiliary empirical functions built-in brings satisfyingresults. The paper presents theoretical-empirical model of the steam-water cycle. Worked out mathematical simulation model containspartial models of the turbine, the regenerative heat exchangers and the condenser. Statistical verification of the model is presented.
Theoretical model simulations for the global Thermospheric Mapping Study (TMS) periods
Rees, D.; Fuller-Rowell, T. J.
Theoretical and semiempirical models of the solar UV/EUV and of the geomagnetic driving forces affecting the terrestrial mesosphere and thermosphere have been used to generate a series of representative numerical time-dependent and global models of the thermosphere, for the range of solar and geoamgnetic activity levels which occurred during the three Thermospheric Mapping Study periods. The simulations obtained from these numerical models are compared with observations, and with the results of semiempirical models of the thermosphere. The theoretical models provide a record of the magnitude of the major driving forces which affected the thermosphere during the study periods, and a baseline against which the actual observed structure and dynamics can be compared.
A theoretical model for evaluation of the design of a hollow-fiber membrane oxygenator.
Tabesh, Hadi; Amoabediny, Ghassem; Poorkhalil, Ali; Khachab, Ali; Kashefi, Ali; Mottaghy, Khosrow
2012-12-01
Geometric data are fundamental to the design of a contactor. The efficiency of a membrane contactor is mainly defined by its mass-transfer coefficient. However, design modifications also have significant effects on the performance of membrane contactors. In a hollow-fiber membrane oxygenator (HFMO), properties such as priming volume and effective membrane surface area (referred to as design specifications) can be determined. In this study, an extensive theoretical model for calculation of geometric data and configuration properties, and, consequently, optimization of the design of an HFMO, is presented. Calculations were performed for Oxyphan(®) hollow-fiber micro-porous membranes, which are frequently used in current HFMOs because of their high gas exchange performance. The results reveal how to regulate both the transverse and longitudinal pitches of fiber bundles to obtain a lower rand width and a greater number of windings. Such modifications assist optimization of module design and, consequently, substantially increase the efficiency of an HFMO. On the basis of these considerations, three values, called efficiency factors, are proposed for evaluation of the design specifications of an HFMO with regard with its performance characteristics (i.e. oxygen-transfer rate and blood pressure drop). Moreover, the performance characteristics of six different commercial HFMOs were measured experimentally, in vitro, under the same standard conditions. Comparison of calculated efficiency factors reveals Quadrox(®) is the oxygenator with the most efficient design with regard with its performance among the oxygenators tested.
Information density converges in dialogue: Towards an information-theoretic model.
Xu, Yang; Reitter, David
2018-01-01
The principle of entropy rate constancy (ERC) states that language users distribute information such that words tend to be equally predictable given previous contexts. We examine the applicability of this principle to spoken dialogue, as previous findings primarily rest on written text. The study takes into account the joint-activity nature of dialogue and the topic shift mechanisms that are different from monologue. It examines how the information contributions from the two dialogue partners interactively evolve as the discourse develops. The increase of local sentence-level information density (predicted by ERC) is shown to apply to dialogue overall. However, when the different roles of interlocutors in introducing new topics are identified, their contribution in information content displays a new converging pattern. We draw explanations to this pattern from multiple perspectives: Casting dialogue as an information exchange system would mean that the pattern is the result of two interlocutors maintaining their own context rather than sharing one. Second, we present some empirical evidence that a model of Interactive Alignment may include information density to explain the effect. Third, we argue that building common ground is a process analogous to information convergence. Thus, we put forward an information-theoretic view of dialogue, under which some existing theories of human dialogue may eventually be unified. Copyright © 2017 Elsevier B.V. All rights reserved.
A general theoretical model for electron transfer reactions in complex systems.
Amadei, Andrea; Daidone, Isabella; Aschi, Massimiliano
2012-01-28
In this paper we present a general theoretical-computational model for treating electron transfer reactions in complex atomic-molecular systems. The underlying idea of the approach, based on unbiased first-principles calculations at the atomistic level, utilizes the definition and the construction of the Diabatic Perturbed states of the involved reactive partners (i.e. the quantum centres in our perturbation approach) as provided by the interaction with their environment, including their mutual interaction. In this way we reconstruct the true Adiabatic states of the reactive partners characterizing the electron transfer process as the fluctuation of the electronic density due to the fluctuating perturbation. Results obtained by using a combination of Molecular Dynamics simulation and the Perturbed Matrix Method on a prototypical intramolecular electron transfer (from 2-(9,9'-dimethyl)fluorene to the 2-naphthalene group separated by a steroidal 5-α-androstane skeleton) well illustrate the accuracy of the method in reproducing both the thermodynamics and the kinetics of the process.
Pennig, Sibylle; Schady, Arthur
2014-01-01
In some regions the exposure to railway noise is extremely concentrated, which may lead to high residential annoyance. Nonacoustical factors contribute to these reactions, but there is limited evidence on the interrelations between the nonacoustical factors that influence railway noise annoyance. The aims of the present study were (1) to examine exposure-response relationships between long-term railway noise exposure and annoyance in a region severely affected by railway noise and (2) to determine a priori proposed interrelations between nonacoustical factors by structural equation analysis. Residents (n = 320) living close to railway tracks in the Middle Rhine Valley completed a socio-acoustic survey. Individual noise exposure levels were calculated by an acoustical simulation model for this area. The derived exposure-response relationships indicated considerably higher annoyance at the same noise exposure level than would have been predicted by the European Union standard curve, particularly for the night-time period. In the structural equation analysis, 72% of the variance in noise annoyance was explained by the noise exposure (L(den)) and nonacoustical variables. The model provides insights into several causal mechanisms underlying the formation of railway noise annoyance considering indirect and reciprocal effects. The concern about harmful effects of railway noise and railway traffic, the perceived control and coping capacity, and the individual noise sensitivity were the most important factors that influence noise annoyance. All effects of the nonacoustical factors on annoyance were mediated by the perceived control and coping capacity and additionally proposed indirect effects of the theoretical model were supported by the data.
Time Analysis of Building Dynamic Response Under Seismic Action. Part 1: Theoretical Propositions
Ufimtcev, E. M.
2017-11-01
The first part of the article presents the main provisions of the analytical approach – the time analysis method (TAM) developed for the calculation of the elastic dynamic response of rod structures as discrete dissipative systems (DDS) and based on the investigation of the characteristic matrix quadratic equation. The assumptions adopted in the construction of the mathematical model of structural oscillations as well as the features of seismic forces’ calculating and recording based on the data of earthquake accelerograms are given. A system to resolve equations is given to determine the nodal (kinematic and force) response parameters as well as the stress-strain state (SSS) parameters of the system’s rods.
Apparel shopping behaviour – Part 1: Towards the development of a conceptual theoretical model
Directory of Open Access Journals (Sweden)
R Du Preez
2003-10-01
Full Text Available Apparel shopping behaviour in a multicultural society is a complex phenomenon. The objective of this paper is to analyse various theoretical models from two disciplines, namely Consumer Behaviour and Clothing, and to develop a new conceptual theoretical model focussing on variables influencing apparel shopping behaviour in a multicultural consumer society. Variables were presented as market dominated, consumer dominated, and/or market and consumer interaction variables. Retailers, marketers, educators, researchers and students could benefit from the proposed model and recommendations are made in this regard. Part 2 reports on an empirical study based on the proposed conceptual theoretical model and discusses market segments and profiles. Opsomming Klere-aankoopgedrag in ’n multi-kulturele verbruikersamelewing is ’n komplekse fenomeen. Die doelwit van die artikel is om verskeie teoretiese modelle vanuit twee dissiplines, naamlik Verbruikersielkunde en Kleding, te analiseer. ’n Nuwe konseptuele teoretiese model is ontwikkel. Die model fokus op veranderlikes wat klereaankoopgedrag in ’n multi-kulturele verbruikersamelewing beïnvloed. Veranderlikes word gegroepeer op grond van die mate waartoe dit oorheers word deur die mark, verbruiker en/of die interaksie tussen die mark en die verbruiker. Kleinhandelaars, bemarkers, opvoeders, navorsers en studente sou kon voordeel trek uit die voorgestelde model. Aanbevelings word in dié verband gemaak. In Deel 2 word ’n empiriese studie gerapporteer. Dié studie is op hierdie voorgestelde konseptuele teoretiese model gegrond en marksegmente sowel as profiele word bespreek.
Monroe, Scott M.; Mineka, Susan
2008-01-01
Our commentary was intended to stimulate discussion about what we perceive to be shortcomings of the mnemonic model and its research base, in the hope of shedding some light on key questions for understanding posttraumatic stress disorder (PTSD). In our view, Berntsen, Rubin, and Bohni have responded only to what they perceive to be shortcomings…
Algebraic Specifications, Higher-order Types and Set-theoretic Models
DEFF Research Database (Denmark)
Kirchner, Hélène; Mosses, Peter David
2001-01-01
, 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...
Theoretical modeling of a new structure of III-V tandem solar cells by ...
African Journals Online (AJOL)
junction solar cell is theoretically investigated by optimizing the thickness of GaAs and GaInPandusing a new optical model to separate the junction between the two solar cell in order to solve problems of tunnel junction and difficulties of fabrication.
Theoretical values of various parameters in the Gummel-Poon model of a bipolar junction transistor
Benumof, R.; Zoutendyk, J.
1986-01-01
Various parameters in the Gummel-Poon model of a bipolar junction transistor are expressed in terms of the basic structure of a transistor. A consistent theoretical approach is used which facilitates an understanding of the foundations and limitations of the derived formulas. The results enable one to predict how changes in the geometry and composition of a transistor would affect performance.
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.
Λc eν) decay in a field theoretic quark model
Indian Academy of Sciences (India)
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 ...
Theoretical model of the density of states of random binary alloys
International Nuclear Information System (INIS)
Zekri, N.; Brezini, A.
1991-09-01
A theoretical formulation of the density of states for random binary alloys is examined based on a mean field treatment. The present model includes both diagonal and off-diagonal disorder and also short-range order. Extensive results are reported for various concentrations and compared to other calculations. (author). 22 refs, 6 figs
A Game-Theoretic Model of Grounding for Referential Communication Tasks
Thompson, William
2009-01-01
Conversational grounding theory proposes that language use is a form of rational joint action, by which dialog participants systematically and collaboratively add to their common ground of shared knowledge and beliefs. Following recent work applying "game theory" to pragmatics, this thesis develops a game-theoretic model of grounding that…
Theoretical investigations of the new Cokriging method for variable-fidelity surrogate modeling
DEFF Research Database (Denmark)
Zimmermann, Ralf; Bertram, Anna
2017-01-01
Cokriging is a variable-fidelity surrogate modeling technique which emulates a target process based on the spatial correlation of sampled data of different levels of fidelity. In this work, we address two theoretical questions associated with the so-called new Cokriging method for variable fidelity...
El-Khouly, Fatma E; van Vuurden, Dannis G; Stroink, Thom; Hulleman, Esther; Kaspers, Gertjan J L; Hendrikse, N Harry; Veldhuijzen van Zanten, Sophie E M
2017-01-01
Despite decades of clinical trials for diffuse intrinsic pontine glioma (DIPG), patient survival does not exceed 10% at two years post-diagnosis. Lack of benefit from systemic chemotherapy may be attributed to an intact bloodbrain barrier (BBB). We aim to develop a theoretical model including
Game-theoretic analysis of supply chain coordination under advertising and price dependent demand
Directory of Open Access Journals (Sweden)
Mona Taheri
2014-06-01
Full Text Available Supply chain members cannot act independently and they need to act as a part of a unified system and coordinated with other members. Therefore, a coordination mechanism may be necessary to motivate members to achieve coordination. In this paper, the coordination problem is studied in a two-level supply chain consisting of a supplier and a retailer where demand is a function of price and advertising expenditures in two scenarios. The first scenario is “No coordination”, and the other scenario is “coordination with Revenue sharing contract”. The models are solved using game theory, Cooperative and Nash equilibrium. Finally, numerical examples are presented indicating that the average expected profit in the second scenario, coordination with revenue sharing, is higher than the first scenario. In addition numerical examples indicate that as price and advertising elasticity to demand increase, profitability of supply chain decreases.
A game theoretical approach for cooperative green mobile operators under roaming price consideration
Ghazzai, Hakim
2015-09-11
In this paper, we investigate the performance of a green mobile operator collaborating with other traditional mobile operators. Its goal is to minimize its CO2 emissions, maximize its profit or achieve or tradeoff between both objectives by offloading its users to neighbor networks and exploiting renewable energies. On the other hand, traditional mobile operators aim to maximize their profits by attracting the maximum number of roamed users. The problem is modeled as a two-level Stackelberg game and its equilibrium is derived. A green mobile operator level that determines how many users per each base station to offload to each neighbor network, and a non-green mobile operator level where operators focus on finding the optimal roaming price. Our simulation results show a significant saving in terms of CO2 emissions compared to the non-cooperation case and that roaming decision depends essentially on the availability of renewable energy in base station sites. © 2015 IEEE.
Zhang, Taotao; Liao, Yangchao; Zhang, Keping; Chen, Jun
2017-05-04
Cement-based piezoelectric materials are widely used due to the fact that compared with common smart materials, they overcome the defects of structure-incompatibility and frequency inconsistency with a concrete structure. However, the present understanding of the mechanical behavior of cement-based piezoelectric smart materials under impact load is still limited. The dynamic characteristics under impact load are of importance, for example, for studying the anti-collision properties of engineering structures and aircraft takeoff-landing safety. Therefore, in this paper, an analytical model was proposed to investigate the dynamic properties of a 2-2 cement-based piezoelectric dual-layer stacked sensor under impact load based on the piezoelectric effect. Theoretical solutions are obtained by utilizing the variable separation and Duhamel integral method. To simulate the impact load and verify the theory, three types of loads, including atransient step load, isosceles triangle load and haversine wave load, are considered and the comparisons between the theoretical results, Li's results and numerical results are presented by using the control variate method and good agreement is found. Furthermore, the influences of several parameters were discussed and other conclusions about this sensor are also given. This should prove very helpful for the design and optimization of the 2-2 cement-based piezoelectric dual-layer stacked sensor in engineering.
Group theoretical construction of two-dimensional models with infinite sets of conservation laws
International Nuclear Information System (INIS)
D'Auria, R.; Regge, T.; Sciuto, S.
1980-01-01
We explicitly construct some classes of field theoretical 2-dimensional models associated with symmetric spaces G/H according to a general scheme proposed in an earlier paper. We treat the SO(n + 1)/SO(n) and SU(n + 1)/U(n) case, giving their relationship with the O(n) sigma-models and the CP(n) models. Moreover, we present a new class of models associated to the SU(n)/SO(n) case. All these models are shown to possess an infinite set of local conservation laws. (orig.)
A CHF Model in Narrow Gaps under Saturated Boiling
International Nuclear Information System (INIS)
Park, Suki; Kim, Hyeonil; Park, Cheol
2014-01-01
Many researchers have paid a great attention to the CHF in narrow gaps due to enormous industrial applications. Especially, a great number of researches on the CHF have been carried out in relation to nuclear safety issues such as in-vessel retention for nuclear power plants during a severe accident. Analytical studies to predict the CHF in narrow gaps have been also reported. Yu et al. (2012) developed an analytical model to predict the CHF on downward facing and inclined heaters based on the model of Kandlikar et al. (2001) for an upward facing heater. A new theoretical model is developed to predict the CHF in narrow gaps under saturated pool boiling. This model is applicable when one side of coolant channels or both sides are heated including the effects of heater orientation. The present model is compared with the experimental CHF data obtained in narrow gaps. A new analytical CHF model is proposed to predict CHF for narrow gaps under saturated pool boiling. This model can be applied to one-side or two-sides heating surface and also consider the effects of heater orientation on CHF. The present model is compared with the experimental data obtained in narrow gaps with one heater. The comparisons indicate that the present model shows a good agreement with the experimental CHF data in the horizontal annular tubes. However, it generally under-predicts the experimental data in the narrow rectangular gaps except the data obtained in the gap thickness of 10 mm and the horizontal downward facing heater
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.
Theoretical and Empirical Review of Asset Pricing Models: A Structural Synthesis
Directory of Open Access Journals (Sweden)
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.
Recent progress in the theoretical modelling of Cepheids and RR Lyrae stars
Marconi, Marcella
2017-09-01
Cepheids and RR Lyrae are among the most important primary distance indicators to calibrate the extragalactic distance ladder and excellent stellar population tracers, for Population I and Population II, respectively. In this paper I first mention some recent theoretical studies of Cepheids and RR Lyrae obtained with different theoretical tools. Then I focus the attention on new results based on nonlinear convective pulsation models in the context of some international projects, including VMC@VISTA and the Gaia collaboration. The open problems for both Cepheids and RR Lyrae are briefly discussed together with some challenging future application.
Ye, Ziran; Wang, Ke; Lu, Chenxi; Jin, Ying; Sui, Chenghua; Yan, Bo; Gao, Fan; Cai, Pinggen; Lv, Bin; Li, Yun; Chen, Naibo; Sun, Guofang; Xu, Fengyun; Ye, Gaoxiang
2018-03-01
We develop a theoretical model that interprets the growth mechanism of zinc (Zn) crystal nanorods on a liquid substrate by thermal evaporation. During deposition, Zn atoms diffuse randomly on an isotropic and quasi-free sustained substrate, the nucleation of the atoms results in the primary nanorod (or seed crystal) growth. Subsequently, a characteristic one-dimensional atomic aggregation is proposed, which leads to the accelerating growth of the crystal nanorod along its preferential growth direction until the growth terminates. The theoretical results are in good agreement with the experimental findings.
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. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
RECENT DEVELOPMENTS OF THE FINANCIAL REPORTING MODEL: THEORETICAL STUDIES IN REVIEW
Bonaci Carmen Giorgiana; Matis Dumitru
2011-01-01
Our paper analyzes the manner in which the financial reporting model evolved towards fair value accounting. After a brief introduction into the context of financial reporting at international level, the analysis focuses on the accounting model of fair value. This is done by synthesizing main studies in accounting research literature that analyze fair value accounting through a theoretical approach. The analysis being developed relies on literature review methodology. The main purpose of the d...
A Theoretical Approach to Financial Therapy: The Development of the Ford Financial Empowerment Model
Directory of Open Access Journals (Sweden)
Kristy L. Archuleta
2012-01-01
Full Text Available 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.
Walsh, Matthew M; Gluck, Kevin A; Gunzelmann, Glenn; Jastrzembski, Tiffany; Krusmark, Michael
2018-03-02
The spacing effect is among the most widely replicated empirical phenomena in the learning sciences, and its relevance to education and training is readily apparent. Yet successful applications of spacing effect research to education and training is rare. Computational modeling can provide the crucial link between a century of accumulated experimental data on the spacing effect and the emerging interest in using that research to enable adaptive instruction. In this paper, we review relevant literature and identify 10 criteria for rigorously evaluating computational models of the spacing effect. Five relate to evaluating the theoretic adequacy of a model, and five relate to evaluating its application potential. We use these criteria to evaluate a novel computational model of the spacing effect called the Predictive Performance Equation (PPE). Predictive Performance Equation combines elements of earlier models of learning and memory including the General Performance Equation, Adaptive Control of Thought-Rational, and the New Theory of Disuse, giving rise to a novel computational account of the spacing effect that performs favorably across the complete sets of theoretic and applied criteria. We implemented two other previously published computational models of the spacing effect and compare them to PPE using the theoretic and applied criteria as guides. © 2018 Cognitive Science Society, Inc.
Decision support models for solid waste management: Review and game-theoretic approaches
Energy Technology Data Exchange (ETDEWEB)
Karmperis, Athanasios C., E-mail: athkarmp@mail.ntua.gr [Sector of Industrial Management and Operational Research, School of Mechanical Engineering, National Technical University of Athens, Iroon Polytechniou 9, 15780 Athens (Greece); Army Corps of Engineers, Hellenic Army General Staff, Ministry of Defence (Greece); Aravossis, Konstantinos; Tatsiopoulos, Ilias P.; Sotirchos, Anastasios [Sector of Industrial Management and Operational Research, School of Mechanical Engineering, National Technical University of Athens, Iroon Polytechniou 9, 15780 Athens (Greece)
2013-05-15
Highlights: ► The mainly used decision support frameworks for solid waste management are reviewed. ► The LCA, CBA and MCDM models are presented and their strengths, weaknesses, similarities and possible combinations are analyzed. ► The game-theoretic approach in a solid waste management context is presented. ► The waste management bargaining game is introduced as a specific decision support framework. ► Cooperative and non-cooperative game-theoretic approaches to decision support for solid waste management are discussed. - Abstract: This paper surveys decision support models that are commonly used in the solid waste management area. Most models are mainly developed within three decision support frameworks, which are the life-cycle assessment, the cost–benefit analysis and the multi-criteria decision-making. These frameworks are reviewed and their strengths and weaknesses as well as their critical issues are analyzed, while their possible combinations and extensions are also discussed. Furthermore, the paper presents how cooperative and non-cooperative game-theoretic approaches can be used for the purpose of modeling and analyzing decision-making in situations with multiple stakeholders. Specifically, since a waste management model is sustainable when considering not only environmental and economic but also social aspects, the waste management bargaining game is introduced as a specific decision support framework in which future models can be developed.
Fiber Bundle Model Under Heterogeneous Loading
Roy, Subhadeep; Goswami, Sanchari
2018-03-01
The present work deals with the behavior of fiber bundle model under heterogeneous loading condition. The model is explored both in the mean-field limit as well as with local stress concentration. In the mean field limit, the failure abruptness decreases with increasing order k of heterogeneous loading. In this limit, a brittle to quasi-brittle transition is observed at a particular strength of disorder which changes with k. On the other hand, the model is hardly affected by such heterogeneity in the limit where local stress concentration plays a crucial role. The continuous limit of the heterogeneous loading is also studied and discussed in this paper. Some of the important results related to fiber bundle model are reviewed and their responses to our new scheme of heterogeneous loading are studied in details. Our findings are universal with respect to the nature of the threshold distribution adopted to assign strength to an individual fiber.
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.
Improving the theoretical foundations of the multi-mode transport model
International Nuclear Information System (INIS)
Bateman, G.; Kritz, A.H.; Redd, A.J.; Erba, M.; Rewoldt, G.; Weiland, J.; Strand, P.; Kinsey, J.E.; Scott, B.
2001-01-01
A new version of the Multi-Mode transport model, designated MMM98, is being developed with improved theoretical foundations, in an ongoing effort to predict the temperature and density profiles in tokamaks. For transport near the edge of the plasma, MMM98 uses a new model based on 3-D nonlinear simulations of drift Alfven mode turbulence. Flow shear stabilization effects have been added to the Weiland model for Ion Temperature Gradient and Trapped Electron Modes, which usually dominates in most of the plasma core. For transport near the magnetic axis at high beta, a new kinetic ballooning mode model has been constructed based on FULL stability code computations. (author)
International Nuclear Information System (INIS)
Grundmann, U.; Rohde, U.; Naumann, B.
1985-01-01
Studies on theoretical simulation of the dynamic behaviour of the AST-500 type reactor primary coolant system are summarized. The first version of a dynamic model in the form of the DYNAST code is described. The DYNAST code is based on a one-dimensional description of the primary coolant circuit including core, draught stack, and intermediate heat exchanger, a vapour dome model, and the point model of neutron kinetics. With the aid of the steady-state computational part of the DYNAST code, studies have been performed on different steady-state operating conditions. Furthermore, some methodological investigations on generalization and improvement of the dynamic model are considered and results presented. (author)
Oscillatory periods in the sun and theoretical models with or without mixing
International Nuclear Information System (INIS)
Scuflaire, R.; Gabriel, M.; Noels, A.; Boury, A.
1975-01-01
Theoretical eigenvalues corresponding to periods less than one hour are presented for a standard solar model and for models of about the solar age which are undergoing a thermal pulse following a fast mixing. The two sets of eigenvalues differ very little, the differences being probably less than the accuracy of Hill's observations, except that the standard solar model presents a quadrupolar oscillation with a 43 min period while the mixed models do not. This period does not seem to be present in Hill's observations. (orig./BJ) [de
Status of molten fuel coolant interaction studies and theoretical modelling work at IGCAR
International Nuclear Information System (INIS)
Rao, P.B.; Singh, Om Pal; Singh, R.S.
1994-01-01
The status of Molten Fuel Coolant Interaction (MFCI) studies is reviewed and some of the important observations made are presented. A new model for MFCI that is developed at IGCAR by considering the various mechanisms in detail is described. The model is validated and compared with the available experimental data and theoretical work at different stages of its development. Several parametric studies that are carried using this model are described. The predictions from this model have been found to be satisfactory, considering the complexity of the MFCI. A need for more comprehensive and MFCI-specific experimental tests is brought out. (author)
Numerical modeling of materials under extreme conditions
Brown, Eric
2014-01-01
The book presents twelve state of the art contributions in the field of numerical modeling of materials subjected to large strain, high strain rates, large pressure and high stress triaxialities, organized into two sections. The first part is focused on high strain rate-high pressures such as those occurring in impact dynamics and shock compression related phenomena, dealing with material response identification, advanced modeling incorporating microstructure and damage, stress waves propagation in solids and structures response under impact. The latter part is focused on large strain-low strain rates applications such as those occurring in technological material processing, dealing with microstructure and texture evolution, material response at elevated temperatures, structural behavior under large strain and multi axial state of stress.
Modeling of STATCOM under different loading conditions
DEFF Research Database (Denmark)
George, G.J.; Ramachandran, Rakesh; Kowsalya, M.
2012-01-01
This paper deals with the study and analysis of Flexible AC Transmission Systems (FACTS), mainly the modeling of STATCOM. Reactive Power Compensation plays a very important role in the transmission of Electric Power. A comparative study of how the reactive power is injected into the transmission ...... system with and without STATCOM under different loading condition is also illustrated in this paper. Simulations are performed using MATLAB/SIMULINK software....
International Nuclear Information System (INIS)
Liu Hongbo; Chen Zhihua; Zhou Ting
2012-01-01
Thermal effects on steel structures exposed to solar radiation are significant and complicated. Furthermore, the temperature variation within a year may result in damage in steel structures considering the solar radiation. In this paper, the temperature distribution of H-shaped steel members was investigated through a systematic experimental and theoretical study in the case of solar radiation. First, an H-shaped steel specimen was designed and its temperature distribution under solar radiation was obtained by a test. After that, a numerical method was proposed to obtain the temperature distribution under solar radiation. This method was based on transient thermal analysis and the analytical result was verified by the above experimental result. Furthermore, a parametric study was conducted to investigate the influence of various solar radiation parameters and orientation of H-shaped steel members on the temperature distribution under solar radiation. Finally, a simplified approach was developed to predict the temperature distribution under solar radiation. Both experimental and numerical results showed that the solar radiation had a significant effect on the temperature distribution of H-shaped steels. Considering the solar radiation, the temperature of the specimen is about 20.6 °C higher than the surrounding ambient air temperature. The temperature distribution under solar radiation was observed to be sensitive to the steel solar radiation absorption and orientation, but insensitive to the solar radiation reflectance. - Highlights: ► The temperature of H-shaped steel members was measured under solar radiation. ► A numerical method was proposed to consider the shadow of solar radiation. ► A parametric study was conducted. ► A simplified approach for temperature distribution was developed and verified.
A THEORETICAL MODEL OF SUPPORTING OPEN SOURCE FRONT END INNOVATION THROUGH IDEA MANAGEMENT
DEFF Research Database (Denmark)
Aagaard, Annabeth
2013-01-01
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...... exploration of active facilitation of open source front end innovation through idea management....
International Nuclear Information System (INIS)
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 2 and NO 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
Energy Technology Data Exchange (ETDEWEB)
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.
Holley, W. R.; Chatterjee, A.
1996-01-01
We have developed a general theoretical model for the interaction of ionizing radiation with chromatin. Chromatin is modeled as a 30-nm-diameter solenoidal fiber comprised of 20 turns of nucleosomes, 6 nucleosomes per turn. Charged-particle tracks are modeled by partitioning the energy deposition between primary track core, resulting from glancing collisions with 100 eV or less per event, and delta rays due to knock-on collisions involving energy transfers >100 eV. A Monte Carlo simulation incorporates damages due to the following molecular mechanisms: (1) ionization of water molecules leading to the formation of OH, H, eaq, etc.; (2) OH attack on sugar molecules leading to strand breaks: (3) OH attack on bases; (4) direct ionization of the sugar molecules leading to strand breaks; (5) direct ionization of the bases. Our calculations predict significant clustering of damage both locally, over regions up to 40 bp and over regions extending to several kilobase pairs. A characteristic feature of the regional damage predicted by our model is the production of short fragments of DNA associated with multiple nearby strand breaks. The shapes of the spectra of DNA fragment lengths depend on the symmetries or approximate symmetries of the chromatin structure. Such fragments have subsequently been detected experimentally and are reported in an accompanying paper (B. Rydberg, Radiat, Res. 145, 200-209, 1996) after exposure to both high- and low-LET radiation. The overall measured yields agree well quantitatively with the theoretical predictions. Our theoretical results predict the existence of a strong peak at about 85 bp, which represents the revolution period about the nucleosome. Other peaks at multiples of about 1,000 bp correspond to the periodicity of the particular solenoid model of chromatin used in these calculations. Theoretical results in combination with experimental data on fragmentation spectra may help determine the consensus or average structure of the
Measuring and Managing Value Co-Creation Process: Overview of Existing Theoretical Models
Directory of Open Access Journals (Sweden)
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
DEFF Research Database (Denmark)
Pessah, Martin Elias
2006-01-01
Recent X-ray variability studies suggest that the log of the square of the fractional rms variability amplitude, rms^2, seems to correlate with the log of the AGN black-hole mass, M_BH, with larger black holes being less variable for a fixed time interval. This has motivated the theoretical...... modeling of the rms^2-M_BH correlation with the aim of constraining AGN masses based on X-ray variability. A viable approach to addressing this problem is to assume an underlying power spectral density with a suitable mass dependence, derive the functional form of the rms^2-M_BH correlation for a given...... to 80% with respect to its true value for the typical sampling patterns used to monitor AGN. We discuss the implications of our results for the derivation of AGN masses using theoretical models of the rms^2-M_BH correlation. (Abridged)...
Developing a theoretical maintenance model for disordered eating in Type 1 diabetes.
Treasure, J; Kan, C; Stephenson, L; Warren, E; Smith, E; Heller, S; Ismail, K
2015-12-01
According to the literature, eating disorders are an increasing problem for more than a quarter of people with Type 1 diabetes and they are associated with accentuated diabetic complications. The clinical outcomes in this group when given standard eating disorder treatments are disappointing. The Medical Research Council guidelines for developing complex interventions suggest that the first step is to develop a theoretical model. To review existing literature to build a theoretical maintenance model for disordered eating in people with Type 1 diabetes. The literature in diabetes relating to models of eating disorder (Fairburn's transdiagnostic model and the dual pathway model) and food addiction was examined and assimilated. The elements common to all eating disorder models include weight/shape concern and problems with mood regulation. The predisposing traits of perfectionism, low self-esteem and low body esteem and the interpersonal difficulties from the transdiagnostic model are also relevant to diabetes. The differences include the use of insulin mismanagement to compensate for breaking eating rules and the consequential wide variations in plasma glucose that may predispose to 'food addiction'. Eating disorder symptoms elicit emotionally driven reactions and behaviours from others close to the individual affected and these are accentuated in the context of diabetes. The next stage is to test the assumptions within the maintenance model with experimental medicine studies to facilitate the development of new technologies aimed at increasing inhibitory processes and moderating environmental triggers. © 2015 The Authors. Diabetic Medicine © 2015 Diabetes UK.
Advancing Women Scientists: Exploring a Theoretically Grounded Climate Change Workshop Model
Silver, Barbara; Prochaska, Janice; Mederer, Helen; Harlow, Lisa; Sherman, Karen
Universities in the United States have an increasing need to recruit the best and the brightest faculty to remain globally competitive, but the majority of schools share a profile that includes a low percentage of women in most of the science, technology, engineering, and math (STEM) disciplines. Changes in university culture are needed to enable departmental diversity growth, to expand offerings and perspectives, and to strengthen the view that STEM is an attractive choice for female students and prospective faculty. This paper describes the theoretical models used to develop a prototype workshop series implemented in departments to help faculty progress in their readiness to advance women scientists, defined as collaborating, mentoring, sharing resources, and generating support through community. The three theoretical underpinnings are the gender-as-structure theory of organizational change, Appreciative Inquiry, and the Transtheoretical Model. These workshops are one aspect of the climate change efforts implemented by the ADVANCE program of the University of Rhode Island.
International Nuclear Information System (INIS)
Sharma, Suresh C.; Gupta, Neha
2015-01-01
A theoretical modeling for the catalyst-assisted growth of graphene sheet in the presence of plasma has been investigated. It is observed that the plasma parameters can strongly affect the growth and field emission properties of graphene sheet. The model developed accounts for the charging rate of the graphene sheet; number density of electrons, ions, and neutral atoms; various elementary processes on the surface of the catalyst nanoparticle; surface diffusion and accretion of ions; and formation of carbon-clusters and large graphene islands. In our investigation, it is found that the thickness of the graphene sheet decreases with the plasma parameters, number density of hydrogen ions and RF power, and consequently, the field emission of electrons from the graphene sheet surface increases. The time evolution of the height of graphene sheet with ion density and sticking coefficient of carbon species has also been examined. Some of our theoretical results are in compliance with the experimental observations
A Theoretical Bayesian Game Model for the Vendor-Retailer Relation
Directory of Open Access Journals (Sweden)
Emil CRIŞAN
2012-06-01
Full Text Available We consider an equilibrated supply chain with two equal partners, a vendor and a retailer (also called newsboy type products supply chain. The actions of each partner are driven by profit. Given the fact that at supply chain level are specific external influences which affect the costs and concordant the profit, we use a game theoretic model for the situation, considering costs and demand. At theoretical level, symmetric and asymmetric information patterns are considered for this situation. There are at every supply chain’s level situations when external factors (such as inflation, raw-material rate influence the situation of each partner even if the information is well shared within the chain. The model we propose considers both the external factors and asymmetric information within a supply chain.
Dou, Kaili; Yu, Ping; Deng, Ning; Liu, Fang; Guan, YingPing; Li, Zhenye; Ji, Yumeng; Du, Ningkai; Lu, Xudong; Duan, Huilong
2017-01-01
Background Chronic disease patients often face multiple challenges from difficult comorbidities. Smartphone health technology can be used to help them manage their conditions only if they accept and use the technology. Objective The aim of this study was to develop and test a theoretical model to predict and explain the factors influencing patients’ acceptance of smartphone health technology for chronic disease management. Methods Multiple theories and factors that may influence patients’ acc...
Experimental and theoretical model of a concentrating photovoltaic and thermal system
International Nuclear Information System (INIS)
Renno, C.; Petito, F.
2016-01-01
Highlights: • Experimental analysis of a concentrating photovoltaic system. • MJ cell electrical characterization and concentration factor evaluation. • Thermal model in ANSYS of the CPV/T system cooling circuit. - Abstract: The experimental and theoretical analysis of a concentrating photovoltaic and thermal system (CPV/T) presented in this paper allows to evaluate the electrical parameters of the system, the concentration factor, the cell temperature in different working conditions and the fluid temperature. In particular, the experimental values of the cell temperature represent the input of a model developed in ANSYS-CFX. This model evaluates the theoretical temperature values of the fluid that flows into the cooling circuit of the CPV/T system, designed with the CATIA software. Hence, both electrical and thermal parameters have been analyzed in order to evaluate the potential energy production of a concentrating photovoltaic and thermal system. Different configurations of the CPV/T system have been analyzed and the value of the concentration factor has been determined by means of an experimental procedure. The experimental and theoretical electric powers are compared in different climatic conditions considering a solar radiation included between 500 and 900 W/m 2 . The electric efficiency is also evaluated as function of solar irradiance and cloudiness. Moreover, the fluid temperature as function of the experimental cell temperature is determined in different working conditions by means of the ANSYS model. The fluid temperature is also theoretically determined varying the operating conditions along the circuit. Finally, a study of the electrical and thermal performances represents a key-factor to develop a more complex prototype of a CPV/T system.
The neural mediators of kindness-based meditation: a theoretical model
Mascaro, Jennifer S.; Darcher, Alana; Negi, Lobsang T.; Raison, Charles L.
2015-01-01
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 c...
The neural mediators of kindness-based meditation: a theoretical model
Jennifer Streiffer Mascaro; Jennifer Streiffer Mascaro; Alana eDarcher; Lobsang Tenzin Negi; Charles eRaison; Charles eRaison
2015-01-01
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 co...
Complex networks under dynamic repair model
Chaoqi, Fu; Ying, Wang; Kun, Zhao; Yangjun, Gao
2018-01-01
Invulnerability is not the only factor of importance when considering complex networks' security. It is also critical to have an effective and reasonable repair strategy. Existing research on network repair is confined to the static model. The dynamic model makes better use of the redundant capacity of repaired nodes and repairs the damaged network more efficiently than the static model; however, the dynamic repair model is complex and polytropic. In this paper, we construct a dynamic repair model and systematically describe the energy-transfer relationships between nodes in the repair process of the failure network. Nodes are divided into three types, corresponding to three structures. We find that the strong coupling structure is responsible for secondary failure of the repaired nodes and propose an algorithm that can select the most suitable targets (nodes or links) to repair the failure network with minimal cost. Two types of repair strategies are identified, with different effects under the two energy-transfer rules. The research results enable a more flexible approach to network repair.
Kim, J.
2016-12-01
Considering high levels of uncertainty, epistemological conflicts over facts and values, and a sense of urgency, normal paradigm-driven science will be insufficient to mobilize people and nation toward sustainability. The conceptual framework to bridge the societal system dynamics with that of natural ecosystems in which humanity operates remains deficient. The key to understanding their coevolution is to understand `self-organization.' Information-theoretic approach may shed a light to provide a potential framework which enables not only to bridge human and nature but also to generate useful knowledge for understanding and sustaining the integrity of ecological-societal systems. How can information theory help understand the interface between ecological systems and social systems? How to delineate self-organizing processes and ensure them to fulfil sustainability? How to evaluate the flow of information from data through models to decision-makers? These are the core questions posed by sustainability science in which visioneering (i.e., the engineering of vision) is an essential framework. Yet, visioneering has neither quantitative measure nor information theoretic framework to work with and teach. This presentation is an attempt to accommodate the framework of self-organizing hierarchical open systems with visioneering into a common information-theoretic framework. A case study is presented with the UN/FAO's communal vision of climate-smart agriculture (CSA) which pursues a trilemma of efficiency, mitigation, and resilience. Challenges of delineating and facilitating self-organizing systems are discussed using transdisciplinary toold such as complex systems thinking, dynamic process network analysis and multi-agent systems modeling. Acknowledgments: This study was supported by the Korea Meteorological Administration Research and Development Program under Grant KMA-2012-0001-A (WISE project).
Theoretical modeling and experimental analysis of solar still integrated with evacuated tubes
Panchal, Hitesh; Awasthi, Anuradha
2017-06-01
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.
A theoretical approach to room acoustic simulations based on a radiative transfer model
DEFF Research Database (Denmark)
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...
The interacting gaps model: reconciling theoretical and numerical approaches to limit-order models
Czech Academy of Sciences Publication Activity Database
Muchnik, L.; Slanina, František; Solomon, S.
2003-01-01
Roč. 330, - (2003), s. 232-239 ISSN 0378-4371 R&D Projects: GA ČR GA202/01/1091 Institutional research plan: CEZ:AV0Z1010914 Keywords : stochastic processes * econophysics Subject RIV: BE - Theoretical Physics Impact factor: 1.180, year: 2003
Ni, Yi; Liu, Chenchen; Chen, Qinmiao; Zhu, Xifang; Dou, Xiaoming
2015-10-01
Programmed step electric field strength is a simple-to-use technique that has already been reported to be effective to enhance the efficiency or speed of DNA electrophoresis. However, a global understanding and the details of this technique are still vague. In this paper, we investigated the influence of programmed step electric field strength by theoretical calculation and concentrated on a basic format named as two-step electric field strength. Both subtypes of two-step electric field strength conditions were considered. The important parameters, such as peak spacing, peak width, resolution, and migration time, were calculated in theory to understand the performance of DNA electrophoresis under programmed step electric field strength. The influence of two-step electric field strength on DNA electrophoresis was clearly revealed on a diagram of resolution versus migration time. Both resolution and speed of DNA electrophoresis under two-step electric field strength conditions are simply expressed by the shape of curves in the diagram. The possible shapes of curve were explored by calculation and shown in this paper. The subtype II of two-step electric field strength brings drastic variation on the resolution. Its limitations of enhancement and deterioration of resolution were predicted in theory. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Modeling ocean wave propagation under sea ice covers
Zhao, Xin; Shen, Hayley H.; Cheng, Sukun
2015-02-01
Operational ocean wave models need to work globally, yet current ocean wave models can only treat ice-covered regions crudely. The purpose of this paper is to provide a brief overview of ice effects on wave propagation and different research methodology used in studying these effects. Based on its proximity to land or sea, sea ice can be classified as: landfast ice zone, shear zone, and the marginal ice zone. All ice covers attenuate wave energy. Only long swells can penetrate deep into an ice cover. Being closest to open water, wave propagation in the marginal ice zone is the most complex to model. The physical appearance of sea ice in the marginal ice zone varies. Grease ice, pancake ice, brash ice, floe aggregates, and continuous ice sheet may be found in this zone at different times and locations. These types of ice are formed under different thermal-mechanical forcing. There are three classic models that describe wave propagation through an idealized ice cover: mass loading, thin elastic plate, and viscous layer models. From physical arguments we may conjecture that mass loading model is suitable for disjoint aggregates of ice floes much smaller than the wavelength, thin elastic plate model is suitable for a continuous ice sheet, and the viscous layer model is suitable for grease ice. For different sea ice types we may need different wave ice interaction models. A recently proposed viscoelastic model is able to synthesize all three classic models into one. Under suitable limiting conditions it converges to the three previous models. The complete theoretical framework for evaluating wave propagation through various ice covers need to be implemented in the operational ocean wave models. In this review, we introduce the sea ice types, previous wave ice interaction models, wave attenuation mechanisms, the methods to calculate wave reflection and transmission between different ice covers, and the effect of ice floe breaking on shaping the sea ice morphology
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…
Gheribi, Aïmen E.; Chartrand, Patrice
2016-02-01
A theoretical model for the description of thermal conductivity of molten salt mixtures as a function of composition and temperature is presented. The model is derived by considering the classical kinetic theory and requires, for its parametrization, only information on thermal conductivity of pure compounds. In this sense, the model is predictive. For most molten salt mixtures, no experimental data on thermal conductivity are available in the literature. This is a hindrance for many industrial applications (in particular for thermal energy storage technologies) as well as an obvious barrier for the validation of the theoretical model. To alleviate this lack of data, a series of equilibrium molecular dynamics (EMD) simulations has been performed on several molten chloride systems in order to determine their thermal conductivity in the entire range of composition at two different temperatures: 1200 K and 1300 K. The EMD simulations are first principles type, as the potentials used to describe the interactions have been parametrized on the basis of first principle electronic structure calculations. In addition to the molten chlorides system, the model predictions are also compared to a recent similar EMD study on molten fluorides and with the few reliable experimental data available in the literature. The accuracy of the proposed model is within the reported numerical and/or experimental errors.
Gheribi, Aïmen E; Chartrand, Patrice
2016-02-28
A theoretical model for the description of thermal conductivity of molten salt mixtures as a function of composition and temperature is presented. The model is derived by considering the classical kinetic theory and requires, for its parametrization, only information on thermal conductivity of pure compounds. In this sense, the model is predictive. For most molten salt mixtures, no experimental data on thermal conductivity are available in the literature. This is a hindrance for many industrial applications (in particular for thermal energy storage technologies) as well as an obvious barrier for the validation of the theoretical model. To alleviate this lack of data, a series of equilibrium molecular dynamics (EMD) simulations has been performed on several molten chloride systems in order to determine their thermal conductivity in the entire range of composition at two different temperatures: 1200 K and 1300 K. The EMD simulations are first principles type, as the potentials used to describe the interactions have been parametrized on the basis of first principle electronic structure calculations. In addition to the molten chlorides system, the model predictions are also compared to a recent similar EMD study on molten fluorides and with the few reliable experimental data available in the literature. The accuracy of the proposed model is within the reported numerical and/or experimental errors.
Darmon, David
2018-03-01
In the absence of mechanistic or phenomenological models of real-world systems, data-driven models become necessary. The discovery of various embedding theorems in the 1980s and 1990s motivated a powerful set of tools for analyzing deterministic dynamical systems via delay-coordinate embeddings of observations of their component states. However, in many branches of science, the condition of operational determinism is not satisfied, and stochastic models must be brought to bear. For such stochastic models, the tool set developed for delay-coordinate embedding is no longer appropriate, and a new toolkit must be developed. We present an information-theoretic criterion, the negative log-predictive likelihood, for selecting the embedding dimension for a predictively optimal data-driven model of a stochastic dynamical system. We develop a nonparametric estimator for the negative log-predictive likelihood and compare its performance to a recently proposed criterion based on active information storage. Finally, we show how the output of the model selection procedure can be used to compare candidate predictors for a stochastic system to an information-theoretic lower bound.
Theoretical and experimental stress analyses of ORNL thin-shell cylinder-to-cylinder model 3
International Nuclear Information System (INIS)
Gwaltney, R.C.; Bolt, S.E.; Corum, J.M.; Bryson, J.W.
1975-06-01
The third in a series of four thin-shell cylinder-to-cylinder models was tested, and the experimentally determined elastic stress distributions were compared with theoretical predictions obtained from a thin-shell finite-element analysis. The models are idealized thin-shell structures consisting of two circular cylindrical shells that intersect at right angles. There are no transitions, reinforcements, or fillets in the junction region. This series of model tests serves two basic purposes: the experimental data provide design information directly applicable to nozzles in cylindrical vessels; and the idealized models provide test results for use in developing and evaluating theoretical analyses applicable to nozzles in cylindrical vessels and to thin piping tees. The cylinder of model 3 had a 10 in. OD and the nozzle had a 1.29 in. OD, giving a d 0 /D 0 ratio of 0.129. The OD/thickness ratios for the cylinder and the nozzle were 50 and 7.68 respectively. Thirteen separate loading cases were analyzed. In each, one end of the cylinder was rigidly held. In addition to an internal pressure loading, three mutually perpendicular force components and three mutually perpendicular moment components were individually applied at the free end of the cylinder and at the end of the nozzle. The experimental stress distributions for all the loadings were obtained using 158 three-gage strain rosettes located on the inner and outer surfaces. The loading cases were also analyzed theoretically using a finite-element shell analysis developed at the University of California, Berkeley. The analysis used flat-plate elements and considered five degrees of freedom per node in the final assembled equations. The comparisons between theory and experiment show reasonably good agreement for this model. (U.S.)
Theoretical and experimental stress analyses of ORNL thin-shell cylinder-to-cylinder model 4
International Nuclear Information System (INIS)
Gwaltney, R.C.; Bolt, S.E.; Bryson, J.W.
1975-06-01
The last in a series of four thin-shell cylinder-to-cylinder models was tested, and the experimentally determined elastic stress distributions were compared with theoretical predictions obtained from a thin-shell finite-element analysis. The models in the series are idealized thin-shell structures consisting of two circular cylindrical shells that intersect at right angles. There are no transitions, reinforcements, or fillets in the junction region. This series of model tests serves two basic purposes: (1) the experimental data provide design information directly applicable to nozzles in cylindrical vessels, and (2) the idealized models provide test results for use in developing and evaluating theoretical analyses applicable to nozzles in cylindrical vessels and to thin piping tees. The cylinder of model 4 had an outside diameter of 10 in., and the nozzle had an outside diameter of 1.29 in., giving a d 0 /D 0 ratio of 0.129. The OD/thickness ratios were 50 and 20.2 for the cylinder and nozzle respectively. Thirteen separate loading cases were analyzed. For each loading condition one end of the cylinder was rigidly held. In addition to an internal pressure loading, three mutually perpendicular force components and three mutually perpendicular moment components were individually applied at the free end of the cylinder and at the end of the nozzle. The experimental stress distributions for each of the 13 loadings were obtained using 157 three-gage strain rosettes located on the inner and outer surfaces. Each of the 13 loading cases was also analyzed theoretically using a finite-element shell analysis developed at the University of California, Berkeley. The analysis used flat-plate elements and considered five degrees of freedom per node in the final assembled equations. The comparisons between theory and experiment show reasonably good agreement for this model. (U.S.)
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.
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
Development of ionospheric data assimilation model under geomagnetic storm conditions
Lin, C. C. H.; Chen, C. H.; Chen, W.; Matsuo, T.
2016-12-01
This study attempts to construct the ionosphere data assimilation model for both quiet and storm time ionosphere. The model assimilates radio occultation and ground-based GNSS observations of global ionosphere using an Ensemble Kalman Filter (EnKF) software of Data Assimilation Research Testbed (DART) together with the theoretical thermosphere-ionosphere-electrodynamic general circulation model (TIEGCM), developed by National Center for Atmospheric Research (NCAR). Using DART-TIEGCM, we investigate the effects of rapid assimilation-forecast cycling for the 26 September 2011 geomagnetic storm period. Effects of various assimilation-forecast cycles, 60-, 30-, and 10-minutes, on the ionospheric forecast are examined by using the global root-mean-square of observation-minus-forecast (OmF) TEC residuals during the entire storm period. Examinations show that the 10-minutes assimilation cycle could greatly improve the quality of model forecast under the storm conditions. Additionally, examinations of storm-time forecast quality for different high latitude forcing given by Heelis and Weimer empirical models are also performed.
Software for energy modelling: a theoretical basis for improvements in the user interface
Energy Technology Data Exchange (ETDEWEB)
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
Directory of Open Access Journals (Sweden)
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.
Seeling, Walter; Plischke, Max; de Bruin, Jeroen S; Schuh, Christian
2015-01-01
Immunosuppressive therapy is a risky necessity after a patient received a kidney transplant. To reduce risks, a knowledge-based system was developed that determines the right dosage of the immunosuppresive agent Tacrolimus. A theoretical model, to classify medication blood levels as well as medication adaptions, was created using data from almost 500 patients, and over 13.000 examinations. This model was then translated into an Arden Syntax knowledge base, and integrated directly into the hospital information system of the Vienna General Hospital. In this paper we give an overview of the construction and integration of such a system.
The dynamics of the nuclear disassembly in a field-theoretical model at finite entropies
International Nuclear Information System (INIS)
Knoll, J.; Strack, B.
1984-10-01
The expansion phase of a hot nuclear system as created in an energetic heavy-ion collision is calculated and discussed by a selfconsistent field-theoretical model. Dynamical instabilities arising during the expansion from strong fluctuations of the one-body density are included explicitely. First multiplicity distributions and mass spectra resulting from a series of numerical runs in a 2+1 dimensional model world are presented. The dependence of break-up dynamics both on the properties of the binding force and possible correlations in the initially compressed hot state are discussed. (orig.)
A theoretical and empirical evaluation and extension of the Todaro migration model.
Salvatore, D
1981-11-01
"This paper postulates that it is theoretically and empirically preferable to base internal labor migration on the relative difference in rural-urban real income streams and rates of unemployment, taken as separate and independent variables, rather than on the difference in the expected real income streams as postulated by the very influential and often quoted Todaro model. The paper goes on to specify several important ways of extending the resulting migration model and improving its empirical performance." The analysis is based on Italian data. excerpt
Dou, Kaili; Yu, Ping; Deng, Ning; Liu, Fang; Guan, YingPing; Li, Zhenye; Ji, Yumeng; Du, Ningkai; Lu, Xudong; Duan, Huilong
2017-12-06
Chronic disease patients often face multiple challenges from difficult comorbidities. Smartphone health technology can be used to help them manage their conditions only if they accept and use the technology. The aim of this study was to develop and test a theoretical model to predict and explain the factors influencing patients' acceptance of smartphone health technology for chronic disease management. Multiple theories and factors that may influence patients' acceptance of smartphone health technology have been reviewed. A hybrid theoretical model was built based on the technology acceptance model, dual-factor model, health belief model, and the factors identified from interviews that might influence patients' acceptance of smartphone health technology for chronic disease management. Data were collected from patient questionnaire surveys and computer log records about 157 hypertensive patients' actual use of a smartphone health app. The partial least square method was used to test the theoretical model. The model accounted for .412 of the variance in patients' intention to adopt the smartphone health technology. Intention to use accounted for .111 of the variance in actual use and had a significant weak relationship with the latter. Perceived ease of use was affected by patients' smartphone usage experience, relationship with doctor, and self-efficacy. Although without a significant effect on intention to use, perceived ease of use had a significant positive influence on perceived usefulness. Relationship with doctor and perceived health threat had significant positive effects on perceived usefulness, countering the negative influence of resistance to change. Perceived usefulness, perceived health threat, and resistance to change significantly predicted patients' intentions to use the technology. Age and gender had no significant influence on patients' acceptance of smartphone technology. The study also confirmed the positive relationship between intention to use
Stress mediation in caregivers of cognitively impaired adults: theoretical model testing.
Irvin, B L; Acton, G J
1996-01-01
The purpose of the study was to test a midrange model of caregiver stress mediation based on Modeling and Role-Modelpan>ing theory. Perceived support and self-worth were examined to determine if these self-care resources had a mediating effect between stress and well-being in caregivers of cognitively impaired adults. The sample of 117 caregivers completed measures of basic need status, perceived support, self-worth, stress, and well-being. There were significant correlations among the study variables in the expected directions. Resources mediated the relationship between stress and well-being, providing tentative support for theoretically proposed linkages.
Wohlers, Christina; Hertel, Guido
2017-04-01
Although there is a trend in today's organisations to implement activity-based flexible offices (A-FOs), only a few studies examine consequences of this new office type. Moreover, the underlying mechanisms why A-FOs might lead to different consequences as compared to cellular and open-plan offices are still unclear. This paper introduces a theoretical framework explaining benefits and risks of A-FOs based on theories from work and organisational psychology. After deriving working conditions specific for A-FOs (territoriality, autonomy, privacy, proximity and visibility), differences in working conditions between A-FOs and alternative office types are proposed. Further, we suggest how these differences in working conditions might affect work-related consequences such as well-being, satisfaction, motivation and performance on the individual, the team and the organisational level. Finally, we consider task-related (e.g. task variety), person-related (e.g. personality) and organisational (e.g. leadership) moderators. Based on this model, future research directions as well as practical implications are discussed. Practitioner Summary: Activity-based flexible offices (A-FOs) are popular in today's organisations. This article presents a theoretical model explaining why and when working in an A-FO evokes benefits and risks for individuals, teams and organisations. According to the model, A-FOs are beneficial when management encourages employees to use the environment appropriately and supports teams.
Theoretical thermal dosimetry produced by an annular phased array system in CT-based patient models
International Nuclear Information System (INIS)
Paulsen, K.D.; Strohbehn, J.W.; Lynch, D.R.
1984-01-01
Theoretical calculations for the specific absorption rate (SAR) and the resulting temperature distributions produced by an annular phased array (APA) type system are made. The finite element numerical method is used in the formulation of both the electromagnetic (EM) and the thermal boundary value problems. A number of detailed patient models based on CT-scan data from the pelvic, visceral, and thoracic regions are generated to stimulate a variety of tumor locations and surrounding normal tissues. The SAR values from the EM solution are input into the bioheat transfer equation, and steady-rate temperature distributions are calculated for a wide variety of blood flow rates. Based on theoretical modeling, the APA shows no preferential heating of superficial over deep-seated tumors. However, in most cases satisfactory thermal profiles (therapeutic volume near 60%) are obtained in all three regions of the human trunk only for tumors with little or no blood flow. Unsatisfactory temperature patterns (therapeutic volume <50%) are found for tumors with moderate to high perfusion rates. These theoretical calculations should aid the clinician in the evaluation of the effectiveness of APA type devices in heating tumors located in the trunk region
Theoretical Model of God: The Key to Correct Exploration of the Universe
Kalanov, Temur Z.
2007-04-01
The problem of the correct approach to exploration of the Universe cannot be solved if there is no solution of the problem of existence of God (Creator, Ruler) in science. In this connection, theoretical proof of existence of God is proposed. The theoretical model of God -- as scientific proof of existence of God -- is the consequence of the system of the formulated axioms. The system of the axioms contains, in particular, the following premises: (1) all objects formed (synthesized) by man are characterized by the essential property: namely, divisibility into aspects; (2) objects which can be mentally divided into aspects are objects formed (synthesized); (3) the system ``Universe'' is mentally divided into aspects. Consequently, the Universe represents the system formed (synthesized); (4) the theorem of existence of God (i.e. Absolute, Creator, Ruler) follows from the principle of logical completeness of system of concepts: if the formed (synthesized) system ``Universe'' exists, then God exists as the Absolute, the Creator, the Ruler of essence (i.e. information) and phenomenon (i.e. material objects). Thus, the principle of existence of God -- the content of the theoretical model of God -- must be a starting-point and basis of correct gnosiology and science of 21 century.
Effective Permittivity of Biological Tissue: Comparison of Theoretical Model and Experiment
Directory of Open Access Journals (Sweden)
Li Gun
2017-01-01
Full Text Available Permittivity of biological tissue is a critical issue for studying the biological effects of electromagnetic fields. Many theories and experiments were performed to measure or explain the permittivity characteristics in biological tissue. In this paper, we investigate the permittivity parameter in biological tissues via theoretical and experimental analysis. Firstly, we analyze the permittivity characteristic in tissue by using theories on composite material. Secondly, typical biological tissues, such as blood, fat, liver, and brain, are measured by HP4275A Multi-Frequency LCR Meter within 10 kHz to 10 MHz. Thirdly, experimental results are compared with the Bottcher-Bordewijk model, the Skipetrov equation, and the Maxwell-Gannett theory. From the theoretical perspective, blood and fat are regarded as the composition of liver and brain because of the high permittivity in blood and the opposite in fat. Volume fraction of blood in liver and brain is analyzed theoretically, and the applicability and the limitation of the models are also discussed. These results benefit further study on local biological effects of electromagnetic fields.
Radionuclide Transport Models Under Ambient Conditions
Energy Technology Data Exchange (ETDEWEB)
G. Moridis; Q. Hu
2000-03-12
The purpose of this Analysis/Model Report (AMR) is to evaluate (by means of 2-D semianalytical and 3-D numerical models) the transport of radioactive solutes and colloids in the unsaturated zone (UZ) under ambient conditions from the potential repository horizon to the water table at Yucca Mountain (YM), Nevada. This is in accordance with the ''AMR Development Plan U0060, Radionuclide Transport Models Under Ambient Conditions'' (CRWMS M and O 1999a). This AMR supports the UZ Flow and Transport Process Model Report (PMR). This AMR documents the UZ Radionuclide Transport Model (RTM). This model considers: the transport of radionuclides through fractured tuffs; the effects of changes in the intensity and configuration of fracturing from hydrogeologic unit to unit; colloid transport; physical and retardation processes and the effects of perched water. In this AMR they document the capabilities of the UZ RTM, which can describe flow (saturated and/or unsaturated) and transport, and accounts for (a) advection, (b) molecular diffusion, (c) hydrodynamic dispersion (with full 3-D tensorial representation), (d) kinetic or equilibrium physical and/or chemical sorption (linear, Langmuir, Freundlich or combined), (e) first-order linear chemical reaction, (f) radioactive decay and tracking of daughters, (g) colloid filtration (equilibrium, kinetic or combined), and (h) colloid-assisted solute transport. Simulations of transport of radioactive solutes and colloids (incorporating the processes described above) from the repository horizon to the water table are performed to support model development and support studies for Performance Assessment (PA). The input files for these simulations include transport parameters obtained from other AMRs (i.e., CRWMS M and O 1999d, e, f, g, h; 2000a, b, c, d). When not available, the parameter values used are obtained from the literature. The results of the simulations are used to evaluate the transport of radioactive
Radionuclide Transport Models Under Ambient Conditions
International Nuclear Information System (INIS)
Moridis, G.; Hu, Q.
2000-01-01
The purpose of this Analysis/Model Report (AMR) is to evaluate (by means of 2-D semianalytical and 3-D numerical models) the transport of radioactive solutes and colloids in the unsaturated zone (UZ) under ambient conditions from the potential repository horizon to the water table at Yucca Mountain (YM), Nevada. This is in accordance with the ''AMR Development Plan U0060, Radionuclide Transport Models Under Ambient Conditions'' (CRWMS M and O 1999a). This AMR supports the UZ Flow and Transport Process Model Report (PMR). This AMR documents the UZ Radionuclide Transport Model (RTM). This model considers: the transport of radionuclides through fractured tuffs; the effects of changes in the intensity and configuration of fracturing from hydrogeologic unit to unit; colloid transport; physical and retardation processes and the effects of perched water. In this AMR they document the capabilities of the UZ RTM, which can describe flow (saturated and/or unsaturated) and transport, and accounts for (a) advection, (b) molecular diffusion, (c) hydrodynamic dispersion (with full 3-D tensorial representation), (d) kinetic or equilibrium physical and/or chemical sorption (linear, Langmuir, Freundlich or combined), (e) first-order linear chemical reaction, (f) radioactive decay and tracking of daughters, (g) colloid filtration (equilibrium, kinetic or combined), and (h) colloid-assisted solute transport. Simulations of transport of radioactive solutes and colloids (incorporating the processes described above) from the repository horizon to the water table are performed to support model development and support studies for Performance Assessment (PA). The input files for these simulations include transport parameters obtained from other AMRs (i.e., CRWMS M and O 1999d, e, f, g, h; 2000a, b, c, d). When not available, the parameter values used are obtained from the literature. The results of the simulations are used to evaluate the transport of radioactive solutes and colloids, and
International Nuclear Information System (INIS)
Mutarelli, Rita de Cassia; Lima, Ana Cecilia de Souza; Sabundjian, Gaiane
2015-01-01
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)
Energy Technology Data Exchange (ETDEWEB)
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)
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.
International Nuclear Information System (INIS)
Xu Jun; You Bo; Li Xin; Cui Juan
2007-01-01
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 0 C -1 with the measured temperature range varying from 0 to 100 0 C
Theoretical analysis of an iron mineral-based magnetoreceptor model in birds
DEFF Research Database (Denmark)
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...... to quantitatively and qualitatively describe the magnetic field effects among particles containing iron minerals. The analysis of forces acting between these subcellular compartments shows a particular dependence on the orientation of the external magnetic field. The iron minerals in the beak are found in the form...... of crystalline maghemite platelets and assemblies of magnetite nanoparticles. We demonstrate that the pull or push to the magnetite assemblies, which are connected to the cell membrane, may reach a value of 0.2 pN-sufficient to excite specific mechanoreceptive membrane channels in the nerve cell. The theoretical...
Sample correlations of infinite variance time series models: an empirical and theoretical study
Directory of Open Access Journals (Sweden)
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.
Modelling human eye under blast loading.
Esposito, L; Clemente, C; Bonora, N; Rossi, T
2015-01-01
Primary blast injury (PBI) is the general term that refers to injuries resulting from the mere interaction of a blast wave with the body. Although few instances of primary ocular blast injury, without a concomitant secondary blast injury from debris, are documented, some experimental studies demonstrate its occurrence. In order to investigate PBI to the eye, a finite element model of the human eye using simple constitutive models was developed. The material parameters were calibrated by a multi-objective optimisation performed on available eye impact test data. The behaviour of the human eye and the dynamics of mechanisms occurring under PBI loading conditions were modelled. For the generation of the blast waves, different combinations of explosive (trinitrotoluene) mass charge and distance from the eye were analysed. An interpretation of the resulting pressure, based on the propagation and reflection of the waves inside the eye bulb and orbit, is proposed. The peculiar geometry of the bony orbit (similar to a frustum cone) can induce a resonance cavity effect and generate a pressure standing wave potentially hurtful for eye tissues.
Directory of Open Access Journals (Sweden)
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.
Theoretical Framework and Model Design for Beautiful Countryside Construction in China
Directory of Open Access Journals (Sweden)
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.
International Nuclear Information System (INIS)
Scialdone, Onofrio; Guarisco, Chiara; Galia, Alessandro
2011-01-01
The electrochemical oxidation of organics in water performed in micro reactors on boron doped diamond (BDD) anode was investigated both theoretically and experimentally in order to find the influence of various operative parameters on the conversion and the current efficiency CE of the process. The electrochemical oxidation of formic acid (FA) was selected as a model case. High conversions for a single passage of the electrolytic solution inside the cell were obtained by operating with proper residence times and low distances between cathode and anode. The effect of initial concentration, flow rate and current density was investigated in detail. Theoretical predictions were in very good agreement with experimental results for both mass transfer control, oxidation reaction control and mixed kinetic regimes in spite of the fact that no adjustable parameters was used. Mass transfer process was successfully modelled by considering for simplicity a constant Sh number (e.g., a constant mass transfer coefficient k m ) for a process performed with no high values of the current intensity to minimize the effect of the gas bubbling on the flowdynamic pattern. For mixed kinetic regimes, two different modelling approaches were used. In the first one, the oxidation of organics at BDD was assumed to be mass transfer controlled and to occur with an intrinsic 100% CE when applied current density is higher than the limiting current density. In the second case, the CE of the process was modelled assuming that the competition between organic and water oxidation depends only on the electrodic material and on the nature and the concentration of the organic. In the latter case a better agreement between experimental data and theoretical predictions was observed.
Modeling of porous concrete elements under load
Demchyna, B. H.; Famuliak, Yu. Ye.; Demchyna, Kh. B.
2017-12-01
It is known that cell concretes are almost immediately destroyed under load, having reached certain critical stresses. Such kind of destruction is called a "catastrophic failure". Process of crack formation is one of the main factors, influencing process of concrete destruction. Modern theory of crack formation is mainly based on the Griffith theory of destruction. However, the mentioned theory does not completely correspond to the structure of cell concrete with its cell structure, because the theory is intended for a solid body. The article presents one of the possible variants of modelling of the structure of cell concrete and gives some assumptions concerning the process of crack formation in such hollow, not solid environment.
Modeling of porous concrete elements under load
Directory of Open Access Journals (Sweden)
Demchyna B.H.
2017-12-01
Full Text Available It is known that cell concretes are almost immediately destroyed under load, having reached certain critical stresses. Such kind of destruction is called a “catastrophic failure”. Process of crack formation is one of the main factors, influencing process of concrete destruction. Modern theory of crack formation is mainly based on the Griffith theory of destruction. However, the mentioned theory does not completely correspond to the structure of cell concrete with its cell structure, because the theory is intended for a solid body. The article presents one of the possible variants of modelling of the structure of cell concrete and gives some assumptions concerning the process of crack formation in such hollow, not solid environment.
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.
Lin, L.; Luo, X.; Qin, F.; Yang, J.
2018-03-01
As one of the combustion products of hydrocarbon fuels in a combustion-heated wind tunnel, water vapor may condense during the rapid expansion process, which will lead to a complex two-phase flow inside the wind tunnel and even change the design flow conditions at the nozzle exit. The coupling of the phase transition and the compressible flow makes the estimation of the condensation effects in such wind tunnels very difficult and time-consuming. In this work, a reduced theoretical model is developed to approximately compute the nozzle-exit conditions of a flow including real-gas and homogeneous condensation effects. Specifically, the conservation equations of the axisymmetric flow are first approximated in the quasi-one-dimensional way. Then, the complex process is split into two steps, i.e., a real-gas nozzle flow but excluding condensation, resulting in supersaturated nozzle-exit conditions, and a discontinuous jump at the end of the nozzle from the supersaturated state to a saturated state. Compared with two-dimensional numerical simulations implemented with a detailed condensation model, the reduced model predicts the flow parameters with good accuracy except for some deviations caused by the two-dimensional effect. Therefore, this reduced theoretical model can provide a fast, simple but also accurate estimation of the condensation effect in combustion-heated hypersonic tunnels.
Directory of Open Access Journals (Sweden)
Kimberly S. Young
2017-10-01
Full Text Available Although, it is not yet officially recognized as a clinical entity which is diagnosable, Internet Gaming Disorder (IGD has been included in section III for further study in the DSM-5 by the American Psychiatric Association (APA, 2013. This is important because there is increasing evidence that people of all ages, in particular teens and young adults, are facing very real and sometimes very severe consequences in daily life resulting from an addictive use of online games. This article summarizes general aspects of IGD including diagnostic criteria and arguments for the classification as an addictive disorder including evidence from neurobiological studies. Based on previous theoretical considerations and empirical findings, this paper examines the use of one recently proposed model, the Interaction of Person-Affect-Cognition-Execution (I-PACE model, for inspiring future research and for developing new treatment protocols for IGD. The I-PACE model is a theoretical framework that explains symptoms of Internet addiction by looking at interactions between predisposing factors, moderators, and mediators in combination with reduced executive functioning and diminished decision making. Finally, the paper discusses how current treatment protocols focusing on Cognitive-Behavioral Therapy for Internet addiction (CBT-IA fit with the processes hypothesized in the I-PACE model.
Theoretical Hill-type muscle and stability: numerical model and application.
Schmitt, S; Günther, M; Rupp, T; Bayer, A; Häufle, D
2013-01-01
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.
Theoretical Hill-Type Muscle and Stability: Numerical Model and Application
Schmitt, S.; Günther, M.; Rupp, T.; Bayer, A.; Häufle, D.
2013-01-01
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. PMID:24319495
Young, Kimberly S.; Brand, Matthias
2017-01-01
Although, it is not yet officially recognized as a clinical entity which is diagnosable, Internet Gaming Disorder (IGD) has been included in section III for further study in the DSM-5 by the American Psychiatric Association (APA, 2013). This is important because there is increasing evidence that people of all ages, in particular teens and young adults, are facing very real and sometimes very severe consequences in daily life resulting from an addictive use of online games. This article summarizes general aspects of IGD including diagnostic criteria and arguments for the classification as an addictive disorder including evidence from neurobiological studies. Based on previous theoretical considerations and empirical findings, this paper examines the use of one recently proposed model, the Interaction of Person-Affect-Cognition-Execution (I-PACE) model, for inspiring future research and for developing new treatment protocols for IGD. The I-PACE model is a theoretical framework that explains symptoms of Internet addiction by looking at interactions between predisposing factors, moderators, and mediators in combination with reduced executive functioning and diminished decision making. Finally, the paper discusses how current treatment protocols focusing on Cognitive-Behavioral Therapy for Internet addiction (CBT-IA) fit with the processes hypothesized in the I-PACE model. PMID:29104555
Theoretical Hill-Type Muscle and Stability: Numerical Model and Application
Directory of Open Access Journals (Sweden)
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.
Multitask Quantile Regression under the Transnormal Model.
Fan, Jianqing; Xue, Lingzhou; Zou, Hui
2016-01-01
We consider estimating multi-task quantile regression under the transnormal model, with focus on high-dimensional setting. We derive a surprisingly simple closed-form solution through rank-based covariance regularization. In particular, we propose the rank-based ℓ 1 penalization with positive definite constraints for estimating sparse covariance matrices, and the rank-based banded Cholesky decomposition regularization for estimating banded precision matrices. By taking advantage of alternating direction method of multipliers, nearest correlation matrix projection is introduced that inherits sampling properties of the unprojected one. Our work combines strengths of quantile regression and rank-based covariance regularization to simultaneously deal with nonlinearity and nonnormality for high-dimensional regression. Furthermore, the proposed method strikes a good balance between robustness and efficiency, achieves the "oracle"-like convergence rate, and provides the provable prediction interval under the high-dimensional setting. The finite-sample performance of the proposed method is also examined. The performance of our proposed rank-based method is demonstrated in a real application to analyze the protein mass spectroscopy data.
Directory of Open Access Journals (Sweden)
Paul Joseph
2015-12-01
Full Text Available Polymeric materials often exhibit complex combustion behaviours encompassing several stages and involving solid phase, gas phase and interphase. A wide range of qualitative, semi-quantitative and quantitative testing techniques are currently available, both at the laboratory scale and for commercial purposes, for evaluating the decomposition and combustion behaviours of polymeric materials. They include, but are not limited to, techniques such as: thermo-gravimetric analysis (TGA, oxygen bomb calorimetry, limiting oxygen index measurements (LOI, Underwriters Laboratory 94 (UL-94 tests, cone calorimetry, etc. However, none of the above mentioned techniques are capable of quantitatively deciphering the underpinning physiochemical processes leading to the melt flow behaviour of thermoplastics. Melt-flow of polymeric materials can constitute a serious secondary hazard in fire scenarios, for example, if they are present as component parts of a ceiling in an enclosure. In recent years, more quantitative attempts to measure the mass loss and melt-drip behaviour of some commercially important chain- and step-growth polymers have been accomplished. The present article focuses, primarily, on the experimental and some theoretical aspects of melt-flow behaviours of thermoplastics under heat/fire conditions.
Energy Technology Data Exchange (ETDEWEB)
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
Li, Dongqing; Wei, Jianxin; Di, Bangrang; Ding, Pinbo; Huang, Shiqi; Shuai, Da
2018-03-01
Understanding the influence of lithology, porosity, permeability, pore structure, fluid content and fluid distribution on the elastic wave properties of porous rocks is of great significance for seismic exploration. However, unlike conventional sandstones, the petrophysical characteristics of tight sandstones are more complex and less understood. To address this problem, we measured ultrasonic velocity in partially saturated tight sandstones under different effective pressures. A new model is proposed, combining the Mavko-Jizba-Gurevich relations and the White model. The proposed model can satisfactorily simulate and explain the saturation dependence and pressure dependence of velocity in tight sandstones. Under low effective pressure, the relationship of P-wave velocity to saturation is pre-dominantly attributed to local (pore scale) fluid flow and inhomogeneous pore-fluid distribution (large scale). At higher effective pressure, local fluid flow gradually decreases, and P-wave velocity gradually shifts from uniform saturation towards patchy saturation. We also find that shear modulus is more sensitive to saturation at low effective pressures. The new model includes wetting ratio, an adjustable parameter that is closely related to the relationship between shear modulus and saturation.
A simplified theoretical model for the laser-induced optogalvanic effect
International Nuclear Information System (INIS)
Mirage, A.
1990-01-01
A simplified theoretical model for an estimate of the optogalvanic effect induced in an electric discharge by resonant laser radiation is presented. This theory is based on the solution of a two-level system rate equation, where the upper level of the stimulated transition is connected to the ground state (lower level) through radiative and collisional processes. The developed relations show that the magnitude and temporal evolution (in the case of pulsed excitation) of the optogalvanic signal depend on the electronic plasma density, electron temperature and on the density of light absorbing centers. (author) [pt
Ding, Ya
2018-01-01
In recent years, many areas of China have been facing increasing problems of soil erosion and land degradation. Conservation tillage, with both economic and ecological benefits, provides a good avenue for Chinese farmers to conserve land as well as secure food production. However, the adoption rate of conservation tillage systems is very low in China. In this paper, the author constructs a theoretical model to explain a farmer’s adoption decision of conservation tillage. The goal is to investigate potential reasons behind the low adoption rate and explores alternative policy tools that can help improve a farmer’s incentive to adopt conservation tillage in China.
Use of Graph-Theoretic Models in Technological Preparation of Assembly Plant
Directory of Open Access Journals (Sweden)
Peter Franzevich Yurchik
2015-05-01
Full Text Available The article examines the existing ways of describing the structural and technological properties of the product in the process of building and repair. It turned out that the main body of work on the preparation process of assembling production uses graph-theoretic model of the product. It is shown that, in general, the structural integrity of many-form connections and relations on the set of components that can not be adequately described by binary structures, such as graphs, networks or trees.
The lack of theoretical support for using person trade-offs in QALY-type models
DEFF Research Database (Denmark)
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...
The neural mediators of kindness-based meditation: a theoretical model
Directory of Open Access Journals (Sweden)
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.
Hyer, E. J.; Reid, J. S.; Schmidt, C. C.; Giglio, L.; Prins, E.
2009-12-01
The diurnal cycle of fire activity is crucial for accurate simulation of atmospheric effects of fire emissions, especially at finer spatial and temporal scales. Estimating diurnal variability in emissions is also a critical problem for construction of emissions estimates from multiple sensors with variable coverage patterns. An optimal diurnal emissions estimate will use as much information as possible from satellite fire observations, compensate known biases in those observations, and use detailed theoretical models of the diurnal cycle to fill in missing information. As part of ongoing improvements to the Fire Location and Monitoring of Burning Emissions (FLAMBE) fire monitoring system, we evaluated several different methods of integrating observations with different temporal sampling. We used geostationary fire detections from WF_ABBA, fire detection data from MODIS, empirical diurnal cycles from TRMM, and simple theoretical diurnal curves based on surface heating. Our experiments integrated these data in different combinations to estimate the diurnal cycles of emissions for each location and time. Hourly emissions estimates derived using these methods were tested using an aerosol transport model. We present results of this comparison, and discuss the implications of our results for the broader problem of multi-sensor data fusion in fire emissions modeling.
Theoretical and experimental stress analyses of ORNL thin-shell cylinder-to-cylinder model 2
International Nuclear Information System (INIS)
Gwaltney, R.C.; Bolt, S.E.; Bryson, J.W.
1975-10-01
Model 2 in a series of four thin-shell cylinder-to-cylinder models was tested, and the experimentally determined elastic stress distributions were compared with theoretical predictions obtained from a thin-shell finite-element analysis. Both the cylinder and the nozzle of model 2 had outside diameters of 10 in., giving a d 0 /D 0 ratio of 1.0, and both had outside diameter/thickness ratios of 100. Sixteen separate loading cases in which one end of the cylinder was rigidly held were analyzed. An internal pressure loading, three mutually perpendicular force components, and three mutually perpendicular moment components were individually applied at the free end of the cylinder and at the end of the nozzle. In addition to these 13 loadings, 3 additional loads were applied to the nozzle (in-plane bending moment, out-of-plane bending moment, and axial force) with the free end of the cylinder restrained. The experimental stress distributions for each of the 16 loadings were obtained using 152 three-gage strain rosettes located on the inner and outer surfaces. All the 16 loading cases were also analyzed theoretically using a finite-element shell analysis. The analysis used flat-plate elements and considered five degrees of freedom per node in the final assembled equations. The comparisons between theory and experiment show reasonably good general agreement, and it is felt that the analysis would be satisfactory for most engineering purposes. (auth)
A theoretical model of speed-dependent steering torque for rolling tyres
Wei, Yintao; Oertel, Christian; Liu, Yahui; Li, Xuebing
2016-04-01
It is well known that the tyre steering torque is highly dependent on the tyre rolling speed. In limited cases, i.e. parking manoeuvre, the steering torque approaches the maximum. With the increasing tyre speed, the steering torque decreased rapidly. Accurate modelling of the speed-dependent behaviour for the tyre steering torque is a key factor to calibrate the electric power steering (EPS) system and tune the handling performance of vehicles. However, no satisfactory theoretical model can be found in the existing literature to explain this phenomenon. This paper proposes a new theoretical framework to model this important tyre behaviour, which includes three key factors: (1) tyre three-dimensional transient rolling kinematics with turn-slip; (2) dynamical force and moment generation; and (3) the mixed Lagrange-Euler method for contact deformation solving. A nonlinear finite-element code has been developed to implement the proposed approach. It can be found that the main mechanism for the speed-dependent steering torque is due to turn-slip-related kinematics. This paper provides a theory to explain the complex mechanism of the tyre steering torque generation, which helps to understand the speed-dependent tyre steering torque, tyre road feeling and EPS calibration.
The neural mediators of kindness-based meditation: a theoretical model.
Mascaro, Jennifer S; Darcher, Alana; Negi, Lobsang T; Raison, Charles L
2015-01-01
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.
Directory of Open Access Journals (Sweden)
Alvaro Ruíz-Baltazar
2015-12-01
Full Text Available In this research, the adsorption capacity of Ag nanoparticles on natural zeolite from Oaxaca is presented. In order to describe the adsorption mechanism of silver nanoparticles on zeolite, experimental adsorption models for Ag ions and Ag nanoparticles were carried out. These experimental data obtained by the atomic absorption spectrophotometry technique were compared with theoretical models such as Lagergren first-order, pseudo-second-order, Elovich, and intraparticle diffusion. Correlation factors R2 of the order of 0.99 were observed. Analysis by transmission electron microscopy describes the distribution of the silver nanoparticles on the zeolite outer surface. Additionally, a chemical characterization of the material was carried out through a dilution process with lithium metaborate. An average value of 9.3 in the Si/Al ratio was observed. Factors such as the adsorption behavior of the silver ions and the Si/Al ratio of the zeolite are very important to support the theoretical models and establish the adsorption mechanism of Ag nanoparticles on natural zeolite.
de Andrade, Rocelito Lopes; de Oliveira, Matheus Costa; Kohlrausch, Emerson Cristofer; Santos, Marcos José Leite
2018-05-01
This work presents a new and simple method for determining IPH (current source dependent on luminance), I0 (reverse saturation current), n (ideality factor), RP and RS, (parallel and series resistance) to build an electrical model for dye sensitized solar cells (DSSCs). The electrical circuit parameters used in the simulation and to generate theoretical curves for the single diode electrical model were extracted from I-V curves of assembled DSSCs. Model validation was performed by assembling five different types of DSSCs and evaluating the following parameters: effect of a TiO2 blocking/adhesive layer, thickness of the TiO2 layer and the presence of a light scattering layer. In addition, irradiance, temperature, series and parallel resistance, ideality factor and reverse saturation current were simulated.
Theoretical models of interstellar shocks. I - Radiative transfer and UV precursors
Shull, J. M.; Mckee, C. F.
1979-01-01
Theoretical models of interstellar radiative shocks are constructed, with special attention to the transfer of ionizing radiation. These models are 'self-consistent' in the sense that the emergent ionizing radiation (the UV precursor) is coupled with the ionization state of H, He, and the metals in the preshock gas. For shock velocities of at least 110 km/s the shocks generate sufficient UV radiation for complete preionization of H and He, the latter to He(+). At lower velocities the preionization can be much smaller, with important consequences for the cooling function, the shock structure, and the emission. For models with shock velocities of 40 to 130 km/s the intensities of the strongest emission lines in the UV, optical, and infrared are tabulated, as well as postshock column densities of metal ions potentially observable by UV absorption spectroscopy. Possible applications to supernova remnants and high-velocity interstellar gas are assessed.
Wang, Feilu; Fujioka, Shinsuke; Nishimura, Hiroaki; Kato, Daiji; Li, Yutong; Zhao, Gang; Zhang, Jie; Takabe, Hideaki
2008-04-01
We composed a time-dependent detailed-configuration-accounting atomic model, which solves rate equations for level population distributions including collisional and radiative atomic processes based on the screened hydrogenic model (R. M. More, Handbook of Plasma Physics, vol. 3, Amsterdam: Elsevier Science Publishers, 1991). This model is used to interpret recent photoionization experiment on the large-scale laser system Gekko-XII (Yamanaka et al., 1981, IEEE, J. Quantum Electron. 17, 1639). In this experiment, the nitrogen gas was bathed in a Planckian radiation field of 80eV and was ionized beyond He-like state (open K-shell). It indicates the ionization parameter is around 10 erg cm/s under near steady-state conditions and the reasonable range of the electron temperature is 20-30eV. The comparison of synthetic and experimental spectra shows reasonable agreement and photoionization plays a significant role in this experiment.
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…
Brian K. Via; chi L. So; Leslie H. Groom; Todd F. Shupe; michael Stine; Jan. Wikaira
2007-01-01
A theoretical model was built predicting the relationship between microfibril angle and lignin content at the Angstrom (A) level. Both theoretical and statistical examination of experimental data supports a square root transformation of lignin to predict microfibril angle. The experimental material used came from 10 longleaf pine (Pinus palustris)...
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
The custodially protected Randall-Sundrum model. Theoretical aspects and flavour phenomenology
International Nuclear Information System (INIS)
Blanke, Monika
2009-01-01
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 L anti b 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 0 - anti K 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 s - anti B 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 custodially protected Randall-Sundrum model. Theoretical aspects and flavour phenomenology
Energy Technology Data Exchange (ETDEWEB)
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.)
A theoretical model for predicting the Peak Cutting Force of conical picks
Directory of Open Access Journals (Sweden)
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.
Marcinkevičiūtė, Lina
2005-01-01
A complex use of employee motivation measures has recently been the issue of discussions, and a practical approach to this issue has become increasingly relevant. The paper aims to prepare an employee motivation model under the changing market conditions. When creating a rational employee motivation model, a certain logical analysis and consistency should be followed, because the creation of a model requires a considerable preparatory work, i.e. the evaluation of the current state of employee...
Qian, Feng; Zhou, Wanlu; Kaluvan, Suresh; Zhang, Haifeng; Zuo, Lei
2018-04-01
Vibration energy harvesting has been extensively studied in recent years to explore a continuous power source for sensor networks and low-power electronics. Torsional vibration widely exists in mechanical engineering; however, it has not yet been well exploited for energy harvesting. This paper presents a theoretical model and an experimental validation of a torsional vibration energy harvesting system comprised of a shaft and a shear mode piezoelectric transducer. The piezoelectric transducer position on the surface of the shaft is parameterized by two variables that are optimized to obtain the maximum power output. The piezoelectric transducer can work in d 15 mode (pure shear mode), coupled mode of d 31 and d 33, and coupled mode of d 33, d 31 and d 15, respectively, when attached at different angles. Approximate expressions of voltage and power are derived from the theoretical model, which gave predictions in good agreement with analytical solutions. Physical interpretations on the implicit relationship between the power output and the position parameters of the piezoelectric transducer is given based on the derived approximate expression. The optimal position and angle of the piezoelectric transducer is determined, in which case, the transducer works in the coupled mode of d 15, d 31 and d 33.
Theoretical models to predict the mechanical behavior of thick composite tubes
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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.
A THEORETICAL MODEL OF SOCIO-PSYCHOLOGICAL SUPPORT WORK PROCESSES FOR MANAGEMENT OF PRODUCTION TEAM
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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.
Photoluminescence of crystalline and disordered BTO:Mn powder: Experimental and theoretical modeling
International Nuclear Information System (INIS)
Gurgel, M.F.C.; Espinosa, J.W.M.; Campos, A.B.; Rosa, I.L.V.; Joya, M.R.; Souza, A.G.; Zaghete, M.A.; Pizani, P.S.; Leite, E.R.; Varela, J.A.; Longo, E.
2007-01-01
Disordered and crystalline Mn-doped BaTiO 3 (BTO:Mn) powders were synthesized by the polymeric precursor method. After heat treatment, the nature of visible photoluminescence (PL) at room temperature in amorphous BTO:Mn was discussed, considering results of experimental and theoretical studies. X-ray diffraction (XRD), PL, and UV-vis were used to characterize this material. Rietveld refinement of the BTO:Mn from XRD data was used to built two models, which represent the crystalline BTO:Mn (BTO:Mn c ) and disordered BTO:Mn (BTO:Mn d ) structures. Theses models were analyzed by the periodic ab initio quantum mechanical calculations using the CRYSTAL98 package within the framework of density functional theory at the B3LYP level. The experimental and theoretical results indicated that PL is related with the degree of disorder in the BTO:Mn powders and also suggests the presence of localized states in the disordered structure
Theoretical study on the inverse modeling of deep body temperature measurement
International Nuclear Information System (INIS)
Huang, Ming; Chen, Wenxi
2012-01-01
We evaluated the theoretical aspects of monitoring the deep body temperature distribution with the inverse modeling method. A two-dimensional model was built based on anatomical structure to simulate the human abdomen. By integrating biophysical and physiological information, the deep body temperature distribution was estimated from cutaneous surface temperature measurements using an inverse quasilinear method. Simulations were conducted with and without the heat effect of blood perfusion in the muscle and skin layers. The results of the simulations showed consistently that the noise characteristics and arrangement of the temperature sensors were the major factors affecting the accuracy of the inverse solution. With temperature sensors of 0.05 °C systematic error and an optimized 16-sensor arrangement, the inverse method could estimate the deep body temperature distribution with an average absolute error of less than 0.20 °C. The results of this theoretical study suggest that it is possible to reconstruct the deep body temperature distribution with the inverse method and that this approach merits further investigation. (paper)
Shevelev Sergey
2017-01-01
The purpose of the work is numerical modelling of heat and mass transfer at evaporation of water drops under the conditions which are typical for a modern chimney-type cooling tower of a thermal power plant. The dual task of heat and mass transfer with movable boundary at convective cooling and evaporation for a ‘drop–humid air’ system in a spherical coordinate system has been solved. It has been shown that there is a rapid decline of water evaporation rate at the initial stage of the process...
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. Copyright © 2015 Elsevier B.V. All rights reserved.
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Predrag Petrović
2013-04-01
Full Text Available The focus of this research holds the most important determinants of real exchange rate covered by various theoretical models. The empirical testing was carried out on the real exchange rate between RSD and Euro for the period from January 2007 to December 2010, which was significantly imposed by availability of consistent time series. The research pertains to five basic model specifications and is based on the testing of time series cointegration by applying Johansen and Engle-Granger’s test. The obtained results have shown that the observed models do not have grounds in empirical data. Time series figuring in models are not cointegrated, and besides that, the estimated cointegration coefficients have signs opposite to the expected ones in large number of cases. In our opinion, the reasons for such findings can be found in the fact that used time series are quite short, i.e. they pertain to the period of only four years, as well as that prices of some significant services are still under the administrative control. Still, despite the aforementioned lacks, we think that our findings can be accepted as preliminary knowledge about the ability of the observed models to explain the dynamics of real exchange rate between RSD and Euro.
RECENT DEVELOPMENTS OF THE FINANCIAL REPORTING MODEL: THEORETICAL STUDIES IN REVIEW
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Bonaci Carmen Giorgiana
2011-07-01
Full Text Available Our paper analyzes the manner in which the financial reporting model evolved towards fair value accounting. After a brief introduction into the context of financial reporting at international level, the analysis focuses on the accounting model of fair value. This is done by synthesizing main studies in accounting research literature that analyze fair value accounting through a theoretical approach. The analysis being developed relies on literature review methodology. The main purpose of the developed analysis is to synthesize main pros and cons as being documented through accounting research literature. Our findings underline both the advantages and shortcomings of fair value accounting and of the recent mixed attribute in nowadays financial reporting practices. The concluding remarks synthesize the obtained results and possible future developments of our analysis.
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Marius Ungerer
2005-10-01
Full Text Available One of the basic assumptions associated with the theoretical model as described in this article is that an organisation (a system can acquire capabilities through intentional strategic and operational initiatives. This intentional capability-building process also implies that the organisation intends to use these capabilities in a constructive way to increase competitive advantage for the firm. Opsomming Een van die basiese aannames wat geassosieer word met die teoretiese model wat in hierdie artikel beskryf word, is dat ’n organisasie (’n stelsel vermoëns deur doelgerigte strategiese en operasionele inisiatiewe kan bekom. Hierdie voorgenome vermoë-skeppingsproses, veronderstel ook dat die onderneming daarop ingestel is om hierdie vermoëns op ’n konstruktiewe wyse te benut om die mededingende voordeel van die organisasie te verhoog.
Directory of Open Access Journals (Sweden)
Marius Ungerer
2005-10-01
Full Text Available One of the basic assumptions associated with the theoretical model as described in this article is that an organization (a system can acquire capabilities through intentional strategic and operational initiatives. This intentional capability-building process also implies that the organisation intends to use these capabilities in a constructive way to increase competitive advantage for the firm. Opsomming Een van die basiese aannames wat geassosieer word met die teoretiese model wat in hierdie artikel beskryf word, is dat ’n organisasie (’n stelsel vermoëns deur doelgerigte strategiese en operasionele inisiatiewe kan bekom. Hierdie voorgenome vermoë-skeppingsproses, veronderstel ook dat die onderneming daarop ingestel is om hierdie vermoëns op ’n konstruktiewe wyse te benut om die mededingende voordeel van die organisasie te verhoog.
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...
The self-schema model: a theoretical approach to the self-concept in eating disorders.
Stein, K F
1996-04-01
Over the last several decades, the self-concept has been implicated as a important determinant of eating disorders (ED). Although considerable progress has been made, questions remain unanswered about the properties of self-concept that distinguish women with an ED from other populations, and mechanisms that link the self-concept to the disordered behaviors. Markus's self-schema model is presented as a theoretical approach to explore the role of the self-concept in ED. To show how the schema model can be integrated with existing work on the self-concept in ED, a framework is proposed that addresses the number, content, and accessibility of the self-schemas. More specifically, it is posited that a limited collection of positive self-schemas available in memory, in combination with a chronically and inflexibly accessible body-weight self-schema, lead to the disordered behaviors associated with anorexia nervosa and bulimia nervosa.
Sharangovich, Sergey N.; Semkin, Artem O.
2017-12-01
In this work a theoretical model of the holographic formation of the polarization diffractive optical elements for the transformation of Gaussian light beams into Bessel-like ones in polymer-dispersed liquid crystals (PDLC) is developed. The model is based on solving the equations of photo-induced Fredericks transition processes for polarization diffractive elements formation by orthogonally polarized light beams with inhomogeneous amplitude and phase profiles. The results of numerical simulation of the material's dielectric tensor changing due to the structure's formation process are presented for various recording beams' polarization states. Based on the results of numerical simulation, the ability to form the diffractive optical elements for light beams transformation by the polarization holography methods is shown.
Theoretical model of two-phase drift flow on natural circulation
International Nuclear Information System (INIS)
Yang Xingtuan; Jiang Shengyao; Zhang Youjie
2002-01-01
Some expressions, such as sub-cooled boiling in the heating section, condensation near the riser inlet, flashing in the riser, and pressure balance in the steam-space, have been theoretically deduced from the physical model of 5 MW heating reactor test loop. The thermodynamics un-equilibrium etc have been considered too. A entire drift model with four equations has been formed, which can be applied to natural circulation system with low pressure and low steam quality. By means of introducing the concept of condensation layer, condensing of bubbles in the sub-cooled liquid has been formulated for the first time. The restrictive equations of the steam space pressure and liquid level have been offered. The equations can be solved by means of integral method, then by using Rung-Kutta-Verner method the final results is obtained
International Nuclear Information System (INIS)
Destombes, Jean-Luc
1978-01-01
This research thesis mainly addresses the experimental and theoretical study of the hydroxyl radical, and the consequences of the obtained results in astrophysics which are studied with a model of pumping by the far infrared. After a recall of notions related to microwave spectroscopy and to molecular radio-astronomy, the author more particularly discusses different aspects of microwave spectroscopy in the interstellar environment and in laboratory. He also reviews different types of spectrometers for unsteady molecules. In the second part, he addresses issues related to the hydroxyl radical (OH): presentation of spectrometers, study of the reaction environment, study of the radical microwave spectrum, identification of transitions by frequency measurements. In the last parts, the author addresses some aspects of interstellar OH masers, and reports the application of some results to simple models of pumping by the far infra red
Theoretical size distribution of fossil taxa: analysis of a null model
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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.
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.
Vasiliadou, I. A.; Katzourakis, V. E.; Syngouna, V. I.; Chrysikopoulos, C. V.
2012-04-01
This study is focused on the transport of Pseudomonas (P.) putida bacterial cells in a three-dimensional model aquifer. The pilot-scale aquifer consisted of a rectangular glass tank with internal dimensions: 120 cm length, 48 cm width, and 50 cm height, carefully packed with well-characterized quartz sand. The P. putida attachment onto the aquifer sand was determined with batch experiments, and was adequately described by a linear isotherm. Transport experiments with a conservative tracer and P. putida were conducted to characterize the aquifer and to investigate the bacterial behavior during transport in water saturated porous media. A three-dimensional, finite-difference numerical model for bacterial transport in saturated, homogeneous porous media was developed and was used to successfully fit the experimental data. Furthermore, theoretical interaction energy calculations suggested that the extended DLVO theory seems to predict bacteria attachment onto the aquifer sand better than the classical DLVO theory.
Toward a comprehensive, theoretical model of compassion fatigue: An integrative literature review.
Coetzee, Siedine K; Laschinger, Heather K S
2018-03-01
This study was an integrative literature review in relation to compassion fatigue models, appraising these models, and developing a comprehensive theoretical model of compassion fatigue. A systematic search on PubMed, EbscoHost (Academic Search Premier, E-Journals, Medline, PsycINFO, Health Source Nursing/Academic Edition, CINAHL, MasterFILE Premier and Health Source Consumer Edition), gray literature, and manual searches of included reference lists was conducted in 2016. The studies (n = 11) were analyzed, and the strengths and limitations of the compassion fatigue models identified. We further built on these models through the application of the conservation of resources theory and the social neuroscience of empathy. The compassion fatigue model shows that it is not empathy that puts nurses at risk of developing compassion fatigue, but rather a lack of resources, inadequate positive feedback, and the nurse's response to personal distress. By acting on these three aspects, the risk of developing compassion fatigue can be addressed, which could improve the retention of a compassionate and committed nurse workforce. © 2017 John Wiley & Sons Australia, Ltd.
Theoretical models for designing a 220-GHz folded waveguide backward wave oscillator
Cai, Jin-Chi; Hu, Lin-Lin; Ma, Guo-Wu; Chen, Hong-Bin; Jin, Xiao; Chen, Huai-Bi
2015-06-01
In this paper, the basic equations of beam-wave interaction for designing the 220 GHz folded waveguide (FW) backward wave oscillator (BWO) are described. On the whole, these equations are mainly classified into small signal model (SSM), large signal model (LSM), and simplified small signal model (SSSM). Using these linear and nonlinear one-dimensional (1D) models, the oscillation characteristics of the FW BWO of a given configuration of slow wave structure (SWS) can be calculated by numerical iteration algorithm, which is more time efficient than three-dimensional (3D) particle-in-cell (PIC) simulation. The SSSM expressed by analytical formulas is innovatively derived for determining the initial values of the FW SWS conveniently. The dispersion characteristics of the FW are obtained by equivalent circuit analysis. The space charge effect, the end reflection effect, the lossy wall effect, and the relativistic effect are all considered in our models to offer more accurate results. The design process of the FW BWO tube with output power of watt scale in a frequency range between 215 GHz and 225 GHz based on these 1D models is demonstrated. The 3D PIC method is adopted to verify the theoretical design results, which shows that they are in good agreement with each other. Project supported by the Innovative Research Foundation of China Academy of Engineering Physics (Grant No. 426050502-2).
Pérard, Marion; Mittring, Nadine; Schweiger, David; Kummer, Christopher; Witt, Claudia M
2015-06-09
Today, the increasing demand for complementary medicine encourages health care providers to adapt and create integrative medicine departments or services within clinics. However, because of their differing philosophies, historical development, and settings, merging the partners (conventional and complementary medicine) is often difficult. It is necessary to understand the similarities and differences in both cultures to support a successful and sustainable integration. The aim of this project was to develop a theoretical model and practical steps that are based on theories from mergers in business to facilitate the implementation of an integrative medicine department. Based on a literature search and expert discussions, the cultures were described and model domains were developed. These were applied to two case studies to develop the final model. Furthermore, a checklist with practical steps was devised. Conventional medicine and complementary medicine have developed different corporate cultures. The final model, which should help to foster integration by bridging between these cultures, is based on four overall aspects: culture, strategy, organizational tools and outcomes. Each culture is represented by three dimensions in the model: corporate philosophy (core and identity of the medicine and the clinic), patient (all characteristics of the professional team's contact with the patient), and professional team (the characteristics of the interactions within the professional team). Overall, corporate culture differs between conventional and complementary medicine; when planning the implementation of an integrative medicine department, the developed model and the checklist can support better integration.
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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.
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Fatma E. El-Khouly
2017-10-01
Full Text Available Despite decades of clinical trials for diffuse intrinsic pontine glioma (DIPG, patient survival does not exceed 10% at two years post-diagnosis. Lack of benefit from systemic chemotherapy may be attributed to an intact bloodbrain barrier (BBB. We aim to develop a theoretical model including relevant physicochemical properties in order to review whether applied chemotherapeutics are suitable for passive diffusion through an intact BBB or whether local administration via convection-enhanced delivery (CED may increase their therapeutic potential. Physicochemical properties (lipophilicity, molecular weight, and charge in physiological environment of anticancer drugs historically and currently administered to DIPG patients, that affect passive diffusion over the BBB, were included in the model. Subsequently, the likelihood of BBB passage of these drugs was ascertained, as well as their potential for intratumoral administration via CED. As only non-molecularly charged, lipophilic, and relatively small sized drugs are likely to passively diffuse through the BBB, out of 51 drugs modeled, only 8 (15%—carmustine, lomustine, erlotinib, vismodegib, lenalomide, thalidomide, vorinostat, and mebendazole—are theoretically qualified for systemic administration in DIPG. Local administration via CED might create more therapeutic options, excluding only positively charged drugs and drugs that are either prodrugs and/or only available as oral formulation. A wide variety of drugs have been administered systemically to DIPG patients. Our model shows that only few are likely to penetrate the BBB via passive diffusion, which may partly explain the lack of efficacy. Drug distribution via CED is less dependent on physicochemical properties and may increase the therapeutic options for DIPG.
Theoretical modelling of photoactive molecular systems: insights using the Density Functional Theory
Energy Technology Data Exchange (ETDEWEB)
Ciofini, I.; Adamo, C. [Ecole Nationale Superieure de Chimie de Paris, Lab. d' Electrochimie et Chimie Analytique, CNRS UMR 7575, 75 - Paris (France); Laine, Ph.P. [Universite Rene-Descartes, Lab. de Chimie et Biochimie Pharmacologiques et Toxicologiques, CNRS UMR 8601, 75 - Paris (France); Bedioui, F. [Ecole Nationale Superieure de Chimie de Paris, Lab. de Pharmacologie Chimique et Genetique, CNRS FRE 2463 and INSERM U 640, 75 - Paris (France); Daul, C.A. [Fribourg Univ., Dept. de Chimie (Switzerland)
2006-02-15
An account of the performance of a modern and efficient approach to Density Functional Theory (DFT) for the prediction of the photophysical behavior of a series of Ru(II) and Os(II) complexes is given. The time-dependent-DFT method was used to interpret their electronic spectra. Two different types of compounds have been analyzed: (1) a complex undergoing a light induced isomerization of one of its coordination bonds; (2) an inorganic dyads expected to undergo intramolecular photoinduced electron transfer to form a charge separated (CS) sate. Besides the noticeable quantitative agreement between computed and experimental absorption spectra, our results allow to clarify, by first principles, both the nature of the excited states and the photochemical behavior of these complex systems, thus underlying the predictive character of the theoretical approach. (authors)
Bioprocess optimization under uncertainty using ensemble modeling
Liu, Yang; Gunawan, Rudiyanto
2017-01-01
The performance of model-based bioprocess optimizations depends on the accuracy of the mathematical model. However, models of bioprocesses often have large uncertainty due to the lack of model identifiability. In the presence of such uncertainty, process optimizations that rely on the predictions of a single “best fit” model, e.g. the model resulting from a maximum likelihood parameter estimation using the available process data, may perform poorly in real life. In this study, we employed ens...
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Yongshui Kang
2014-10-01
Full Text Available Water-bearing rocks exposed to freezing temperature can be subjected to freeze–thaw cycles leading to crack initiation and propagation, which are the main causes of frost damage to rocks. Based on the Griffith theory of brittle fracture mechanics, the crack initiation criterion, propagation direction, and crack length under freezing pressure and far-field stress are analyzed. Furthermore, a calculation method is proposed for the stress intensity factor (SIF of the crack tip under non-uniformly distributed freezing pressure. The formulae for the crack/fracture propagation direction and length of the wing crack under freezing pressure are obtained, and the mechanism for coalescence of adjacent cracks is investigated. In addition, the necessary conditions for different coalescence modes of cracks are studied. Using the topology theory, a new algorithm for frost crack propagation is proposed, which has the capability to define the crack growth path and identify and update the cracked elements. A model that incorporates multiple cracks is built by ANSYS and then imported into FLAC3D. The SIFs are then calculated using a FISH procedure, and the growth path of the freezing cracks after several calculation steps is demonstrated using the new algorithm. The proposed method can be applied to rocks containing fillings such as detritus and slurry.
Pan, Yamin; Liu, Xianhu; Hao, Xiaoqiong; Schubert, Dirk W
2016-11-30
Blends of carbon black (CB)-filled co-continuous immiscible polystyrene/poly(methyl-methacrylate) (PS/PMMA) with a PS/PMMA ratio of 50/50 and CB selectively located in the PS phase have been prepared by melt blending. The simultaneous evolution of conductivity and phase morphology of blend composites was investigated under shear and in the quiescent state at 200 °C. It was found that shear deformation had a significant influence on the conductivity of the unfilled PS/PMMA blend and its composites, which was attributed to the change of phase morphology during shear. After the shear stress of 10 kPa, the conductivity of PS/PMMA blends filled with 2 vol% of CB decreased by about two orders of magnitude and the phase morphology transformed from a fine co-continuous structure into a highly elongated lamellar structure. The deformation of phase morphology and the decrease of conductivity were weakened upon decreasing the shear stress or increasing the CB concentration. During subsequent recovery, pronounced phase structure coarsening was observed in the mixture and the conductivity increased as well. A simple model describing the behavior of conductivity under shear deformation was derived and utilized for the description of the experimental data. For the first time, the Burgers model was used to describe the conductivity, and the viscoelastic and viscoplastic parameters were deduced by fitting the conductivity under shear. The results obtained in this study provide a deeper insight into the evolution of phase structure in the conductive polymer blend composite induced by shear deformation.
Cheng, Neal
A detailed investigation into the interaction between highly ionizing x-ray radiation and nanomaterials was performed. To begin, a theoretical model of the interactions of the system was created as an attempt to understand the relationship between the nanomaterial and the radiation-generated species. The model spans from the physical regime (10-10 s), during which the chemical species generated from radiolytic cleavage of water diffuses and reacts. A combination of methods was used in the simulation: Monte Carlo, Brownian diffusion, and kinetic rate equations. Several experimental systems were created for the purpose of testing the radio-enhancing effects of nanomaterials and the validity of the model: Firstly, the effects of localized energy deposition by gold nanoparticles were examined in a system consisting of 3 nm gold nanoparticles conjugated to DNA. In this system, single-strand breaks on DNA were used to probe the spatial distribution of energy nanometers around the nanoparticle. A comparison of the local energy deposition by gold nanoparticles versus global energy deposition by water was examined using the model. An additional 150% in DNA strand breaks was observed at 100 mM Tris (2-Amino-2-hydroxymethyl-propane-1,3-diol, represents 5nm diffusion distance), yet according to the model, the energy deposition of 10 gold nanoparticles on a strand of DNA accounts for only an additional 20%. Several explanations were given, such as the different reactivity of radical at short distance, the cross-linking of multiple DNA to a single nanoparticle, and geometric configuration of DNA. Secondly, the effect of remote energy deposition was examined in a system consisting of gold nanotubules and free-floating DNA, containing a composition of 50 wt.% Au/50 wt.% H2O. There was no localized energy deposition due to non-conjugation and a maximum enhancement of 1400% was found at 10 mM Tris, which was inconsistent with the expected enhancement of ˜14000%. The result was
Universe in the theoretical model «Evolving matter»
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Bazaluk Oleg
2013-04-01
Full Text Available The article critically examines modern model of the Universe evolution constructed by efforts of a group of scientists (mathematicians, physicists and cosmologists from the world's leading universities (Oxford and Cambridge Universities, Yale, Columbia, New York, Rutgers and the UC Santa Cruz. The author notes its strengths, but also points to shortcomings. Author believes that this model does not take into account the most important achievements in the field of biochemistry and biology (molecular, physical, developmental, etc., as well as neuroscience and psychology. Author believes that in the construction of model of the Universe evolution, scientists must take into account (with great reservations the impact of living and intelligent matter on space processes. As an example, the author gives his theoretical model "Evolving matter". In this model, he shows not only the general dependence of the interaction of cosmic processes with inert, living and intelligent matter, but also he attempts to show the direct influence of systems of living and intelligent matter on the acceleration of the Universe's expansion.
The phantom derivative method when a structure model is available: about its theoretical basis.
Burla, Maria Cristina; Cascarano, Giovanni Luca; Giacovazzo, Carmelo; Polidori, Giampiero
2017-05-01
This study clarifies why, in the phantom derivative (PhD) approach, randomly created structures can help in refining phases obtained by other methods. For this purpose the joint probability distribution of target, model, ancil and phantom derivative structure factors and its conditional distributions have been studied. Since PhD may use n phantom derivatives, with n ≥ 1, a more general distribution taking into account all the ancil and derivative structure factors has been considered, from which the conditional distribution of the target phase has been derived. The corresponding conclusive formula contains two components. The first is the classical Srinivasan & Ramachandran term, relating the phases of the target structure with the model phases. The second arises from the combination of two correlations: that between model and derivative (the first is a component of the second) and that between derivative and target. The second component mathematically codifies the information on the target phase arising from model and derivative electron-density maps. The result is new, and explains why a random structure, uncorrelated with the target structure, adds useful information on the target phases, provided a model structure is known. Some experimental tests aimed at checking if the second component really provides information on ϕ (the target phase) were performed; the favourable results confirm the correctness of the theoretical calculations and of the corresponding analysis.
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.
Campbell, E. E.; Oliveira, J. D. C.; Lamparelli, R.; Soares, J.; Monteiro, L. A.; Jaiswal, D.; Sheehan, J. J.; Figueiredo, G. K. D. A.; Lynd, L. R.
2017-12-01
Accessing the changes in net primary production (NPP) from grassland in the globe has important applications, e.g. can identify where land have been degraded or in opposite site have been intensified. The aim of this study is to identify the changes occurred in grassland production due management practices and climate change. A recent comparison between a theoretical model of aboveground NPP and satellite data will be performed for the years 2000 to 2003. The theoretical model links NPP to climate, defined as total annual rainfall. Satellite data will use the total annual NPP from MODIS sensor (MOD17A3), that each pixel (spatial resolution of 1 km) include biome type information, daily meteorological data and the fraction absorbed of photosynthetic active radiation (FPAR) and leaf area index (LAI). Both NPP results were set in pastureland that is occupied by ruminants based on year 2000. The correlation between total NPP's values on year 2000 was 0.77. Therefore, the change in the differences between these models can reflect management practices and climate change impacts on grassland biomass production and also the reasonability of using both databases for predicting yield gap. The different from both NPP estimates will be then classified in three groups: no significant difference, significant increase and significant decrease. The outcome results will show the fluctuations in biomass from grassland worldwide. The regions with ongoing pasture degradation will be indentified, and can suggest a need for improvement. In the other hand, pastureland with significant increase in biomass will offer an example of intensification potential. The tendency of the pastureland in each region can give a support for policy makers in order to achieve a sustainability use of the land. Financial Support: FAPESP process 2017/06037-4, 2016/08741-8, 2017/08970-0, 2016/08742-4 and 2014/26767-9
Directory of Open Access Journals (Sweden)
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.
A theoretical model for flow boiling CHF from short concave heaters
International Nuclear Information System (INIS)
Galloway, J.E.; Mudawar, I.
1995-01-01
Experiments were performed to enable the development of a new theoretical mode for the enhancement in CHF commonly observed with flow boiling on concave heater as compared to straight heaters. High-speed video imaging and photomicrography were employed to capture the trigger mechanism for CHF each type heater. A wavy vapor layer was observed to engulf the heater surface in each case, permitting liquid access to the surface only in regions where depressions (troughs) in the liquid vapor interface made contact with the surface. CHF in each case occurred when the pressure force exerted upon the wavy vapor-liquid inter ace in the contact region could no longer overcome the momentum of the vapor produced in these regional. Shorter interfacial wavelengths with greater curvature were measured on the curve, heater than on the straight heater, promoting a greater pressure force on the wave interface and a corresponding increase in CHF for the curved heater. A theoretics. CHF model is developed from these observations, based upon a new theory for hydrodynamic instability, along a curved interface. CHF data are predicted with good accuracy for both heaters. 23 refs., 9 figs
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Saleh Alwahaishi
2013-03-01
Full Text Available The world has changed a lot in the past years. The rapid advances in technology and the changing of the communication channels have changed the way people work and, for many, where do they work from. The Internet and mobile technology, the two most dynamic technological forces in modern information and communications technology (ICT are converging into one ubiquitous mobile Internet service, which will change our way of both doing business and dealing with our daily routine activities. As the use of ICT expands globally, there is need for further research into cultural aspects and implications of ICT. The acceptance of Information Technology (IT has become a fundamental part of the research plan for most organizations (Igbaria 1993. In IT research, numerous theories are used to understand users’ adoption of new technologies. Various models were developed including the Technology Acceptance Model, Theory of Reasoned Action, Theory of Planned Behavior, and recently, the Unified Theory of Acceptance and Use of Technology. Each of these models has sought to identify the factors which influence a citizen’s intention or actual use of information technology. Drawing on the UTAUT model and Flow Theory, this research composes a new hybrid theoretical framework to identify the factors affecting the acceptance and use of Mobile Internet -as an ICT application- in a consumer context. The proposed model incorporates eight constructs: Performance Expectancy, Effort Expectancy, Facilitating Conditions, Social Influences, Perceived Value, Perceived Playfulness, Attention Focus, and Behavioral intention. Data collected online from 238 respondents in Saudi Arabia were tested against the research model, using the structural equation modeling approach. The proposed model was mostly supported by the empirical data. The findings of this study provide several crucial implications for ICT and, in particular, mobile Internet service practitioners and researchers
Jones, Matt; Love, Bradley C
2011-08-01
The prominence of Bayesian modeling of cognition has increased recently largely because of mathematical advances in specifying and deriving predictions from complex probabilistic models. Much of this research aims to demonstrate that cognitive behavior can be explained from rational principles alone, without recourse to psychological or neurological processes and representations. We note commonalities between this rational approach and other movements in psychology - namely, Behaviorism and evolutionary psychology - that set aside mechanistic explanations or make use of optimality assumptions. Through these comparisons, we identify a number of challenges that limit the rational program's potential contribution to psychological theory. Specifically, rational Bayesian models are significantly unconstrained, both because they are uninformed by a wide range of process-level data and because their assumptions about the environment are generally not grounded in empirical measurement. The psychological implications of most Bayesian models are also unclear. Bayesian inference itself is conceptually trivial, but strong assumptions are often embedded in the hypothesis sets and the approximation algorithms used to derive model predictions, without a clear delineation between psychological commitments and implementational details. Comparing multiple Bayesian models of the same task is rare, as is the realization that many Bayesian models recapitulate existing (mechanistic level) theories. Despite the expressive power of current Bayesian models, we argue they must be developed in conjunction with mechanistic considerations to offer substantive explanations of cognition. We lay out several means for such an integration, which take into account the representations on which Bayesian inference operates, as well as the algorithms and heuristics that carry it out. We argue this unification will better facilitate lasting contributions to psychological theory, avoiding the pitfalls
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
Hofman, Petra; Hoppe, Thomas
2013-01-01
The goal of this paper is to elaborate a theoretical framework and research design for further research related to the question ‘What practices and underlying drivers explain adoption of integral sustainable energy innovations in the Dutch housing sector?’. Although there are many efforts to speed
Semenova, L. E.
2018-04-01
The hyper-Raman scattering of light by LO-phonons under two-photon excitation near resonance with the An=2 exciton level in the wurtzite semiconductors A2B6 was theoretically investigated, taking into account the influence of the complex structure of the top valence band.
Directory of Open Access Journals (Sweden)
Martha Fabiola Contreras Higuera
2013-06-01
Full Text Available Power Line Communications (PLC refers to a group of technologies that allow to establish communication processes under the use of the grid as a physical means of transmission. The use of the grid as a physical means of transmission of information is not a new idea. Until a few years ago, the use of PLC had been limited to the implementation of solutions of control, automation and monitoring of sensors; which did not require a high bandwidth for its operation.During the late 1990s due to the new technological developments and the need to implement new alternatives for transfer of information, it was possible to reach speeds on the order of the Mbps, establishing the possibility of making use of the electricity network as a network of access. The current state of technology PLC allows to reach speeds of up to 200Mbps, which has enabled the transformation of the grid in a true network of band wide, capable of supporting data, voice and video provided by a telecommunications operator. The use of PLC-based network adapters allow easily design LANs and broadband communications through the electrical network, making any outlet in a point of connection for the user, without the need for wiring additional to existing ones. The electrical network is a structure which so far has been exclusively used for the transport of electrical energy. However, it is possible to make use of this network in processes of communication and transmission of information such as: voice, data and video; Bearing in mind that grid had not been designed for this purpose. The performance is without doubt one of the aspects of greatest interest in the global analysis in networks LAN, due to the effect it produces on the end user. Basically, the most common parameters for evaluating the performance of a network are: Throughput, use of the canal and various measures of retardation. In this article is presented a simple analysis of the HomePlug 1.0 standard applied to the
Directory of Open Access Journals (Sweden)
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
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.
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.
How Do Trading Firms Upgrade Skills and Technology: A Theoretical Model
Directory of Open Access Journals (Sweden)
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
2016-12-01
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.
Physical Protection System Design Analysis against Insider Threat based on Game Theoretic Modeling
International Nuclear Information System (INIS)
Kim, Kyo-Nam; Suh, Young-A; Yim, Man-Sung; Schneider, Erich
2015-01-01
This study explores the use of game-theoretic modeling of physical protection analysis by incorporating the implications of an insider threat. The defender-adversary interaction along with the inclusion of an insider is demonstrated using a simplified test case problem at an experimental fast reactor system. Non-detection probability and travel time are used as a baseline of physical protection parameters in this model. As one of the key features of the model is its ability to choose among security upgrades given the constraints of a budget, the study also performed cost benefit analysis for security upgrades options. In this study, we analyzed the expected adversarial path and security upgrades with a limited budget with insider threat modeled as increasing the non-detection probability. Our test case problem categorized three types of adversary paths assisted by the insider and derived the largest insider threat in terms of the budget for security upgrades. More work needs to be done to incorporate complex dimensions of insider threats, which include but are not limited to: a more realistic mapping of insider threat, accounting for information asymmetry between the adversary, insider, and defenders, and assignment of more pragmatic parameter values
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.
On theoretical models of gene expression evolution with random genetic drift and natural selection.
Ogasawara, Osamu; Okubo, Kousaku
2009-11-20
The relative contributions of natural selection and random genetic drift are a major source of debate in the study of gene expression evolution, which is hypothesized to serve as a bridge from molecular to phenotypic evolution. It has been suggested that the conflict between views is caused by the lack of a definite model of the neutral hypothesis, which can describe the long-run behavior of evolutionary change in mRNA abundance. Therefore previous studies have used inadequate analogies with the neutral prediction of other phenomena, such as amino acid or nucleotide sequence evolution, as the null hypothesis of their statistical inference. In this study, we introduced two novel theoretical models, one based on neutral drift and the other assuming natural selection, by focusing on a common property of the distribution of mRNA abundance among a variety of eukaryotic cells, which reflects the result of long-term evolution. Our results demonstrated that (1) our models can reproduce two independently found phenomena simultaneously: the time development of gene expression divergence and Zipf's law of the transcriptome; (2) cytological constraints can be explicitly formulated to describe long-term evolution; (3) the model assuming that natural selection optimized relative mRNA abundance was more consistent with previously published observations than the model of optimized absolute mRNA abundances. The models introduced in this study give a formulation of evolutionary change in the mRNA abundance of each gene as a stochastic process, on the basis of previously published observations. This model provides a foundation for interpreting observed data in studies of gene expression evolution, including identifying an adequate time scale for discriminating the effect of natural selection from that of random genetic drift of selectively neutral variations.
Fisher, Gary A.
2013-01-01
A mixed method study explored a theoretical model that employed, combined, and added to the theories of self-determination, the reading engagement perspective, and the four-phase model of interest to motivate adolescent struggling readers to read for pleasure. The model adds to the existing body of research because it specifies an instructional…
Recent Advances in the Theoretical Modeling of Pulsating Low-mass He-core White Dwarfs
Córsico, A. H.; Althaus, L. G.; Calcaferro, L. M.; Serenelli, A. M.; Kepler, S. O.; Jeffery, C. S.
2017-03-01
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 second gradient theoretical framework for hierarchical multiscale modeling of materials
Energy Technology Data Exchange (ETDEWEB)
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.
Falling chains as variable-mass systems: theoretical model and experimental analysis
International Nuclear Information System (INIS)
De Sousa, Célia A; Costa, Pedro; Gordo, Paulo M
2012-01-01
In this paper, we revisit, theoretically and experimentally, the fall of a folded U-chain and of a pile-chain. The model calculation implies the division of the whole system into two subsystems of variable mass, allowing us to explore the role of tensional contact forces at the boundary of the subsystems. This justifies, for instance, that the folded U-chain falls faster than the acceleration due to the gravitational force. This result, which matches quite well with the experimental data independently of the type of chain, implies that the falling chain is well described by energy conservation. We verify that these conclusions are not observed for the pile-chain motion. (paper)
Directory of Open Access Journals (Sweden)
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.
Type of cultural orientation and empathy in brazilians: Verification of a theoretical model
Directory of Open Access Journals (Sweden)
Nilton Formiga
2013-01-01
Full Text Available The events in contemporary have affected the social spaces, economic and cultural as well the interpersonal relations. It is believed that an individualist or collectivist orientation would influence people's ability to recognition of his capacity for interpersonal resonance: to empathize. The present study aims to verify a theoretical model in which the type of cultural orientation does associate with empathy. 456 subjects, male and female, ages from 12 to 67 years, of different educational levels of public and private institutions in the cities of Joao Pessoa-PB and Rio de Janeiro-RJ, answered to the Multidimensional Scale of Interpersonal Reactivity, the Scale of the Attributes of Individualistic and Collectivistic Cultural Orientation and socio-demographic data. There was a positive association between the collectivist orientation and empathy, on the other hand, individualistic orientation was associated negatively with empathy. It also highlighted the existence of a higher average score on collectivism which influences the high score on empathy.
A Theoretical Model for Digital Reverberations of City Spaces and Public Places
DEFF Research Database (Denmark)
Zimmerman, Chris; Hansen, Kjeld; Vatrapu, Ravi
2014-01-01
around them. The popularization of location-aware technolo¬gies thus contributes to the changing meaning of locations in cities. In contrast to the technological focus in the emerging discourses on smart cities and big data, this paper offers an alternative view of the three lenses of Social, Local...... 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...... to locations, which transforms the space for other people who use the same services. Such locations acquire relevance and reshape social and spatial interactions through increased use on social media as people ‘check-in’ to places, photograph or ‘like’ them. Collectively the authors are marking-up the city...
Modeling an Application's Theoretical Minimum and Average Transactional Response Times
Energy Technology Data Exchange (ETDEWEB)
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.
Adulthood Social Class and Union Interest: A First Test of a Theoretical Model.
Mellor, Steven
2016-10-02
A serial mediation model of union interest was tested. Based on theoretical notes provided by Mellor and Golay (in press), adulthood social class was positioned as a predictor of willingness to join a labor union, with success/failure attributions at work and willingness to share work goals positioned as intervening variables. Data from U.S. nonunion employees (N = 560) suggested full mediation after effects were adjusted for childhood social class. In sequence, adulthood social class predicted success/failure attributions at work, success/failure attributions at work predicted willingness to share work goals, and willingness to share work goals predicted willingness to join. Implications for socioeconomic status (SES) research and union expansion are discussed.
Psycho-social aspects of youth unemployment: an interpretative theoretical model.
Hendry, L B; Raymond, M J
1986-12-01
By utilizing representative samples of short-term (n = 33), long term (n = 14) unemployed adolescents and YTS trainees (n = 49) in North-East Scotland, the present study attempted to identify psycho-social variables involved in the individual adolescent's ability to cope with unemployment. The research was built around a series of semi-structured interviews with all subjects. Results suggested a variety of apparent contradictions--family support vs. parental pressure; informal community-based education as helpful vs. school education as irrelevant; high aspirations as reinforcing or frustrating; peer groups as supportive or socially constraining; time structure as welcome or monotonous and restrictive; self-esteem being sapped or maintained aggressively and defensively high. From the data a theoretical model is offered which attempts to resolve the paradoxes by interpreting the experience of unemployment for young people in terms of positive and negative "trade-offs".
International Nuclear Information System (INIS)
Vazquez Villa, A.; Delgado Atencio, J. A.; Vazquez y Montiel, S.; Cunill Rodriguez, M.; Martinez Rodriguez, A. E.; Ramos, J. Castro; Villanueva, A.
2010-01-01
Optical coherence tomography (OCT) is a non-invasive low coherent interferometric technique that provides cross-sectional images of turbid media. OCT is based on the classical Michelson interferometer where the mirror of the reference arm is oscillating and the signal arm contains a biological sample. In this work, we analyzed theoretically the heterodyne optical signal adopting the so called extended Huygens-Fresnel principle (EHFP). We use simulated OCT images with known optical properties to test an algorithm developed by ourselves to recover the scattering coefficient and we recovered the scattering coefficient with a relative error less than 5% for noisy signals. In addition, we applied this algorithm to OCT images from phantoms of known optical properties; in this case curves were indistinguishable. A revision of the validity of the analytical model applied to our system should be done.
Directory of Open Access Journals (Sweden)
Ping Li
2018-03-01
Full Text Available In this paper, performances of vibration energy harvester combined piezoelectric (PE and electromagnetic (EM mechanism are studied by theoretical analysis, simulation and experimental test. For the designed harvester, electromechanical coupling modeling is established, and expressions of vibration response, output voltage, current and power are derived. Then, performances of the harvester are simulated and tested; moreover, the power charging rechargeable battery is realized through designed energy storage circuit. By the results, it’s found that compared with piezoelectric-only and electromagnetic-only energy harvester, the hybrid energy harvester can enhance the output power and harvesting efficiency; furthermore, at the harmonic excitation, output power of harvester linearly increases with acceleration amplitude increasing; while it enhances with acceleration spectral density increasing at the random excitation. In addition, the bigger coupling strength, the bigger output power is, and there is the optimal load resistance to make the harvester output the maximal power.
Directory of Open Access Journals (Sweden)
Florencia Stelzer
2014-01-01
Full Text Available Executive functions (EF have been defined as a series of higher-order cognitive processes which allow the control of thought, behavior and affection according to the achievement of a goal. Such processes present a lengthy postnatal development which matures completely by the end of adolescence. In this article we make a review of some of the main models of EF development during childhood. The aim of this work is to describe the state of the art related to the topic, identifying the main theoretical difficulties and methodological limitations associated with the different proposed paradigms. Finally, some suggestions are given to cope with such difficulties, emphasizing that the development of an ontology of EF could be a viable alternative to counter them. We believe that futture researches should guide their efforts toward the development of that ontology.
Theoretical and experimental study of coupled rocking-swivelling model of guyed mast shaft
Directory of Open Access Journals (Sweden)
Urushadze Shota
2015-01-01
Full Text Available Systematic monitoring of rotational vibration (both torsion and swivelling of guyed mast shafts has been performed in ITAM since 2005. The occurrence of this phenomenon is conditioned by the fact that the guy ropes are attached to the construction of the shaft, i.e. out of its axis. The simple static calculation model serves for making the proof of the occurrence of the torsional moment, affecting the shaft, which is guyed by three ropes. The exact theoretical solution of the real phenomenon assumes the introduction of dynamics of guy ropes, which vibrate in 3D shapes during the shaft’s movement along the orbit and it’s torsion (swivelling.
Energy Technology Data Exchange (ETDEWEB)
Mantsinen, M. [Helsinki Univ. of Technology, Espoo (Finland). Dept. of Technical Physics
1999-06-01
Heating with electromagnetic waves in the ion cyclotron range of frequencies (ICRF) is a well-established method for auxiliary heating of present-day tokamak plasmas and is envisaged as one of the main heating techniques for the International Thermonuclear Experimental Reactor (ITER) and future reactor plasmas. In order to predict the performance of ICRF heating in future machines, it is important to benchmark present theoretical modelling with experimental results on present tokamaks. This thesis reports on development and experimental evaluation of theoretical models for ICRF heating at the Joint European Torus (JET). Several ICRF physics effects and scenarios have been studied. Direct importance to the ITER is the theoretical analysis of ICRF heating experiments with deuterium-tritium (D-T) plasmas. These experiments clearly demonstrate the potential of ICRF heating for auxiliary heating of reactor plasmas. In particular, scenarios with potential for good bulk ion heating and enhanced D-T fusion reactivity have been identified. Good bulk ion heating is essential for reactor plasmas in order to obtain a high ion temperature and a high fusion reactivity. In JET good bulk ion heating with ICRF waves has been achieved in high-performance discharges by adding ICRF heating to neutral beam injection. In these experiments, as in other JET discharges where damping at higher harmonics of the ion cyclotron frequency takes place, so-called finite Larmor radius (FLR) effects play an important role. Due to FLR effects, the resonating ion velocity distribution function can have a strong influence on the power deposition. Evidence for this effect has been obtained from the third harmonic deuterium heating experiments. Because of FLR effects, the wave-particle interaction can also become weak at certain ion energies, which prevents resonating ions from reaching higher energies. When interacting with the wave, an ion receives not only a change in energy but also a change in
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.
Directory of Open Access Journals (Sweden)
Juexuan Long
Full Text Available In this paper, we present a combined theoretical and experimental study of the propagation of calcium signals in multicellular structures composed of human endothelial cells. We consider multicellular structures composed of a single chain of cells as well as a chain of cells with a side branch, namely a "T" structure. In the experiments, we investigate the result of applying mechano-stimulation to induce signaling in the form of calcium waves along the chain and the effect of single and dual stimulation of the multicellular structure. The experimental results provide evidence of an effect of architecture on the propagation of calcium waves. Simulations based on a model of calcium-induced calcium release and cell-to-cell diffusion through gap junctions shows that the propagation of calcium waves is dependent upon the competition between intracellular calcium regulation and architecture-dependent intercellular diffusion.
Pejov, Ljupčo; Petreska, Irina; Kocarev, Ljupčo
2015-12-28
A theoretical proof of the concept that a particularly designed graphene-based moletronics device, constituted by two semi-infinite graphene subunits, acting as source and drain electrodes, and a central benzenoid ring rotator (a "quantum dot"), could act as a field-controllable molecular switch is outlined and analyzed with the density functional theory approach. Besides the ideal (0 K) case, we also consider the operation of such a device under realistic operating (i.e., finite-temperature) conditions. An in-depth insight into the physics behind device controllability by an external field was gained by thorough analyses of the torsional potential of the dot under various conditions (absence or presence of an external gating field with varying strength), computing the torsional correlation time and transition probabilities within the Bloembergen-Purcell-Pound formalism. Both classical and quantum mechanical tunneling contributions to the intramolecular rotation were considered in the model. The main idea that we put forward in the present study is that intramolecular rotors can be controlled by the gating field even in cases when these groups do not possess a permanent dipole moment (as in cases considered previously by us [I. Petreska et al., J. Chem. Phys. 134, 014708-1-014708-12 (2011)] and also by other groups [P. E. Kornilovitch et al., Phys. Rev. B 66, 245413-1-245413-7 (2002)]). Consequently, one can control the molecular switching properties by an external electrostatic field utilizing even nonpolar intramolecular rotors (i.e., in a more general case than those considered so far). Molecular admittance of the currently considered graphene-based molecular switch under various conditions is analyzed employing non-equilibrium Green's function formalism, as well as by analysis of frontier molecular orbitals' behavior.
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
Directory of Open Access Journals (Sweden)
Miguel ZAPATA-ROS
2015-04-01
Full Text Available This paper aims at setting the bases for the construction of a theoretical model of learning and of elaboration of knowledge, within connected learning environments. The starting point is a critical view of connectivism, and a premise: the study and recognition of existing theories, since their scope is still under development as regards their potentialities and affordances when applied in social, ubiquitous environments. The paper also includes reflections and a hypothesis on the causes that underlie in the origin of connectivism in its actual stage of development in the Information and Knowledge Society, in order to use the obtained conclusions as the bases of a new model, at a later phase.
Bioprocess optimization under uncertainty using ensemble modeling.
Liu, Yang; Gunawan, Rudiyanto
2017-02-20
The performance of model-based bioprocess optimizations depends on the accuracy of the mathematical model. However, models of bioprocesses often have large uncertainty due to the lack of model identifiability. In the presence of such uncertainty, process optimizations that rely on the predictions of a single "best fit" model, e.g. the model resulting from a maximum likelihood parameter estimation using the available process data, may perform poorly in real life. In this study, we employed ensemble modeling to account for model uncertainty in bioprocess optimization. More specifically, we adopted a Bayesian approach to define the posterior distribution of the model parameters, based on which we generated an ensemble of model parameters using a uniformly distributed sampling of the parameter confidence region. The ensemble-based process optimization involved maximizing the lower confidence bound of the desired bioprocess objective (e.g. yield or product titer), using a mean-standard deviation utility function. We demonstrated the performance and robustness of the proposed strategy in an application to a monoclonal antibody batch production by mammalian hybridoma cell culture. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.
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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.
Chude-Okonkwo, Uche A. K.; Malekian, Reza; Maharaj, B. T.
2015-12-01
Inspired by biological systems, molecular communication has been proposed as a new communication paradigm that uses biochemical signals to transfer information from one nano device to another over a short distance. The biochemical nature of the information transfer process implies that for molecular communication purposes, the development of molecular channel models should take into consideration diffusion phenomenon as well as the physical/biochemical kinetic possibilities of the process. The physical and biochemical kinetics arise at the interfaces between the diffusion channel and the transmitter/receiver units. These interfaces are herein termed molecular antennas. In this paper, we present the deterministic propagation model of the molecular communication between an immobilized nanotransmitter and nanoreceiver, where the emission and reception kinetics are taken into consideration. Specifically, we derived closed-form system-theoretic models and expressions for configurations that represent different communication systems based on the type of molecular antennas used. The antennas considered are the nanopores at the transmitter and the surface receptor proteins/enzymes at the receiver. The developed models are simulated to show the influence of parameters such as the receiver radius, surface receptor protein/enzyme concentration, and various reaction rate constants. Results show that the effective receiver surface area and the rate constants are important to the system's output performance. Assuming high rate of catalysis, the analysis of the frequency behavior of the developed propagation channels in the form of transfer functions shows significant difference introduce by the inclusion of the molecular antennas into the diffusion-only model. It is also shown that for t > > 0 and with the information molecules' concentration greater than the Michaelis-Menten kinetic constant of the systems, the inclusion of surface receptors proteins and enzymes in the models
Theoretical Modelling of Immobilization of Cadmium and Nickel in Soil Using Iron Nanoparticles
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Vaidotas Danila
2017-09-01
Full Text Available Immobilization using zero valent using iron nanoparticles is a soil remediation technology that reduces concentrations of dissolved contaminants in soil solution. Immobilization of heavy metals in soil can be achieved through heavy metals adsorption and surface complexation reactions. These processes result in adsorption of heavy metals from solution phase and thus reducing their mobility in soil. Theoretical modelling of heavy metals, namely, cadmium and nickel, adsorption using zero valent iron nanoparticles was conducted using Visual MINTEQ. Adsorption of cadmium and nickel from soil solutions were modelled separately and when these metals were dissolved together. Results have showed that iron nanoparticles can be successfully applied as an effective adsorbent for cadmium and nickel removal from soil solution by producing insoluble compounds. After conducting the modelling of dependences of Cd+2 and Ni+2 ions adsorption on soil solution pH using iron nanoparticles, it was found that increasing pH of solution results in the increase of these ions adsorption. Adsorption of cadmium reached approximately 100% when pH ≥ 8.0, and adsorption of nickel reached approximately 100% when pH ≥ 7.0. During the modelling, it was found that adsorption of heavy metals Cd and Ni mostly occur, when one heavy metal ion is chemically adsorbed on two sorption sites. During the adsorption modelling, when Cd+2 and Ni+2 ions were dissolved together in acidic phase, it was found that adsorption is slightly lower than modelling adsorption of these metals separately. It was influenced by the competition of Cd+2 and Ni+2 ions for sorption sites on the surface of iron nanoparticles.
Theoretical analysis of transcranial Hall-effect stimulation based on passive cable model
International Nuclear Information System (INIS)
Yuan Yi; Li Xiao-Li
2015-01-01
Transcranial Hall-effect stimulation (THS) is a new stimulation method in which an ultrasonic wave in a static magnetic field generates an electric field in an area of interest such as in the brain to modulate neuronal activities. However, the biophysical basis of simulating the neurons remains unknown. To address this problem, we perform a theoretical analysis based on a passive cable model to investigate the THS mechanism of neurons. Nerve tissues are conductive; an ultrasonic wave can move ions embedded in the tissue in a static magnetic field to generate an electric field (due to Lorentz force). In this study, a simulation model for an ultrasonically induced electric field in a static magnetic field is derived. Then, based on the passive cable model, the analytical solution for the voltage distribution in a nerve tissue is determined. The simulation results showthat THS can generate a voltage to stimulate neurons. Because the THS method possesses a higher spatial resolution and a deeper penetration depth, it shows promise as a tool for treating or rehabilitating neuropsychiatric disorders. (paper)
Märk, Julia; Theiss, Christoph; Schmitt, Franz-Josef; Laufer, Jan
2015-03-01
Fluorophores, such as exogenous dyes and genetically expressed proteins, exhibit radiative relaxation with long excited state lifetimes. This can be exploited for PA detection based on dual wavelength excitation using pump and probe wavelengths that coincide with the absorption and emission spectra, respectively. While the pump pulse raises the fluorophore to a long-lived excited state, simultaneous illumination with the probe pulse reduces the excited state lifetime due to stimulated emission (SE).This leads to a change in thermalized energy, and hence PA signal amplitude, compared to single wavelength illumination. By introducing a time delay between pump and probe pulses, the change in PA amplitude can be modulated. Since the effect is not observed in endogenous chromophores, it provides a contrast mechanism for the detection of fluorophores via PA difference imaging. In this study, a theoretical model of the PA signal generation in fluorophores was developed and experimentally validated. The model is based on a system of coupled rate equations, which describe the spatial and temporal changes in the population of the molecular energy levels of a fluorophore as a function of pump-probe energy and concentration. This allows the prediction of the thermalized energy distribution, and hence the time-resolved PA signal amplitude. The model was validated by comparing its predictions to PA signals measured in solutions of rhodamine 6G, a well-known laser dye, and Atto680, a NIR fluorophore.
Specialists' meeting on theoretical modelling of LMFBR fuel pin behaviour. Summary report
International Nuclear Information System (INIS)
1979-12-01
The purpose of the meeting was to provide an opportunity for exchanging views of theoretical modelling of LMFBR fuel pin behaviour and to summarise the IWGFR member countries' knowledge in this field. The special emphasis was placed on normal operating conditions. The technical part of the meeting was divided into six sessions, as follows: An overview of fuel modelling studies; Key factors and basic phenomena relevant to fuel pin behaviour modelling; Application to steady state operation and normal transients; Experimental validation through pins in service and specific irradiation experiments; Advanced fuels; and Brief review of existing codes. During the meeting, papers were presented by the delegates on behalf of their countries or organization. The papers, which are included in this report, were either in the form of a general survey of the subject, or on specific technical subjects. In each subject area presentations appropriate to the subject were made from the submitted papers. The presentations were followed by discussions of the questions raised and summary is made
Overcoming barriers in care for the dying: Theoretical analysis of an innovative program model.
Wallace, Cara L
2016-08-01
This article explores barriers to end-of-life (EOL) care (including development of a death denying culture, ongoing perceptions about EOL care, poor communication, delayed access, and benefit restrictions) through the theoretical lens of symbolic interactionism (SI), and applies general systems theory (GST) to a promising practice model appropriate for addressing these barriers. The Compassionate Care program is a practice model designed to bridge gaps in care for the dying and is one example of a program offering concurrent care, a recent focus of evaluation though the Affordable Care Act. Concurrent care involves offering curative care alongside palliative or hospice care. Additionally, the program offers comprehensive case management and online resources to enrollees in a national health plan (Spettell et al., 2009).SI and GST are compatible and interrelated theories that provide a relevant picture of barriers to end-of-life care and a practice model that might evoke change among multiple levels of systems. These theories promote insight into current challenges in EOL care, as well as point to areas of needed research and interventions to address them. The article concludes with implications for policy and practice, and discusses the important role of social work in impacting change within EOL care.
A Game-Theoretical Model to Improve Process Plant Protection from Terrorist Attacks.
Zhang, Laobing; Reniers, Genserik
2016-12-01
The New York City 9/11 terrorist attacks urged people from academia as well as from industry to pay more attention to operational security research. The required focus in this type of research is human intention. Unlike safety-related accidents, security-related accidents have a deliberate nature, and one has to face intelligent adversaries with characteristics that traditional probabilistic risk assessment techniques are not capable of dealing with. In recent years, the mathematical tool of game theory, being capable to handle intelligent players, has been used in a variety of ways in terrorism risk assessment. In this article, we analyze the general intrusion detection system in process plants, and propose a game-theoretical model for security management in such plants. Players in our model are assumed to be rational and they play the game with complete information. Both the pure strategy and the mixed strategy solutions are explored and explained. We illustrate our model by an illustrative case, and find that in our case, no pure strategy but, instead, a mixed strategy Nash equilibrium exists. © 2016 Society for Risk Analysis.
Evidential Model Validation under Epistemic Uncertainty
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Wei Deng
2018-01-01
Full Text Available This paper proposes evidence theory based methods to both quantify the epistemic uncertainty and validate computational model. Three types of epistemic uncertainty concerning input model data, that is, sparse points, intervals, and probability distributions with uncertain parameters, are considered. Through the proposed methods, the given data will be described as corresponding probability distributions for uncertainty propagation in the computational model, thus, for the model validation. The proposed evidential model validation method is inspired by the idea of Bayesian hypothesis testing and Bayes factor, which compares the model predictions with the observed experimental data so as to assess the predictive capability of the model and help the decision making of model acceptance. Developed by the idea of Bayes factor, the frame of discernment of Dempster-Shafer evidence theory is constituted and the basic probability assignment (BPA is determined. Because the proposed validation method is evidence based, the robustness of the result can be guaranteed, and the most evidence-supported hypothesis about the model testing will be favored by the BPA. The validity of proposed methods is illustrated through a numerical example.
3. Theoretical Physics Division
International Nuclear Information System (INIS)
For the period September 1980 - Aug 1981, the studies in theoretical physics divisions have been compiled under the following headings: in nuclear physics, nuclear structure, nuclear reactions and intermediate energies; in particle physics, NN and NantiN interactions, dual topological unitarization, quark model and quantum chromodynamics, classical and quantum field theories, non linear integrable equations and topological preons and Grand unified theories. A list of publications, lectures and meetings is included [fr
A unifying model of genome evolution under parsimony.
Paten, Benedict; Zerbino, Daniel R; Hickey, Glenn; Haussler, David
2014-06-19
Parsimony and maximum likelihood methods of phylogenetic tree estimation and parsimony methods for genome rearrangements are central to the study of genome evolution yet to date they have largely been pursued in isolation. We present a data structure called a history graph that offers a practical basis for the analysis of genome evolution. It conceptually simplifies the study of parsimonious evolutionary histories by representing both substitutions and double cut and join (DCJ) rearrangements in the presence of duplications. The problem of constructing parsimonious history graphs thus subsumes related maximum parsimony problems in the fields of phylogenetic reconstruction and genome rearrangement. We show that tractable functions can be used to define upper and lower bounds on the minimum number of substitutions and DCJ rearrangements needed to explain any history graph. These bounds become tight for a special type of unambiguous history graph called an ancestral variation graph (AVG), which constrains in its combinatorial structure the number of operations required. We finally demonstrate that for a given history graph G, a finite set of AVGs describe all parsimonious interpretations of G, and this set can be explored with a few sampling moves. This theoretical study describes a model in which the inference of genome rearrangements and phylogeny can be unified under parsimony.
Development of Simple Drying Model for Performance Prediction of Solar Dryer: Theoretical Analysis
DEFF Research Database (Denmark)
Singh, Shobhana; Kumar, Subodh
2012-01-01
of experimental drying parameters. A laboratory model of mixed-mode solar dryer system is tested with cylindrical potato samples of thickness 5 and 18 mm under simulated indoor conditions. The potato samples were dried at a constant absorbed thermal energy of 750 W/m2 and air mass flow rate of 0.011 kg......An analytical moisture diffusion model which considers the influence of external resistance to mass transfer is developed to predict thermal performance of dryer system. The moisture diffusion coefficient, Deff that is necessary to evaluate the prediction model has been determined in terms....../sec. The proposed model with computed moisture diffusion coefficient, Deff has been utilized to predict dimensionless moisture content, φ for each test condition of a given dryer design. In order to validate the model, statistical test methods such as mean absolute error (MAE), root mean square error (RSME...
Modelling of diurnal cycle under climate change
Energy Technology Data Exchange (ETDEWEB)
Eliseev, A.V.; Bezmenov, K.V.; Demchenko, P.F.; Mokhov, I.I.; Petoukhov, V.K. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Atmospheric Physics
1995-12-31
The observed diurnal temperature range (DTR) displays remarkable change during last 30 years. Land air DTR generally decreases under global climate warming due to more significant night minimum temperature increase in comparison with day maximum temperature increase. Atmosphere hydrological cycle characteristics change under global warming and possible background aerosol atmosphere content change may cause essential errors in the estimation of DTR tendencies of change under global warming. The result of this study is the investigation of cloudiness effect on the DTR and blackbody radiative emissivity diurnal range. It is shown that in some cases (particularly in cold seasons) it results in opposite change in DTR and BD at doubled CO{sub 2} atmosphere content. The influence of background aerosol is the same as the cloudiness one
Directory of Open Access Journals (Sweden)
Amy Hardy
2017-05-01
Full Text Available In recent years, empirical data and theoretical accounts relating to the relationship between childhood victimization and psychotic experiences have accumulated. Much of this work has focused on co-occurring Posttraumatic Stress Disorder or putative causal mechanisms in isolation from each other. The complexity of posttraumatic stress reactions experienced in psychosis remains poorly understood. This paper therefore attempts to synthesize the current evidence base into a theoretically informed, multifactorial model of posttraumatic stress in psychosis. Three trauma-related vulnerability factors are proposed to give rise to intrusions and to affect how people appraise and cope with them. First, understandable attempts to survive trauma become habitual ways of regulating emotion, manifesting in cognitive-affective, behavioral and interpersonal responses. Second, event memories, consisting of perceptual and episodic representations, are impacted by emotion experienced during trauma. Third, personal semantic memory, specifically appraisals of the self and others, are shaped by event memories. It is proposed these vulnerability factors have the potential to lead to two types of intrusions. The first type is anomalous experiences arising from emotion regulation and/or the generation of novel images derived from trauma memory. The second type is trauma memory intrusions reflecting, to varying degrees, the retrieval of perceptual, episodic and personal semantic representations. It is speculated trauma memory intrusions may be experienced on a continuum from contextualized to fragmented, depending on memory encoding and retrieval. Personal semantic memory will then impact on how intrusions are appraised, with habitual emotion regulation strategies influencing people’s coping responses to these. Three vignettes are outlined to illustrate how the model accounts for different pathways between victimization and psychosis, and implications for therapy are
Modeling of Current Transformers Under Saturation Conditions
Directory of Open Access Journals (Sweden)
Martin Prochazka
2006-01-01
Full Text Available During a short circuit the input signal of the relay can be distort by the magnetic core saturation of the current transformer. It is useful to verify the behavior of CT by a mathematical model. The paper describes one phase and three phase models and it presents some methods of how to analyze and classify a deformed secondary current
A game-theoretic model of interspecific brood parasitism with sequential decisions.
Harrison, M D; Broom, M
2009-02-21
The interaction between hosts and parasites in bird populations has been studied extensively. This paper uses game-theoretic methods to model this interaction. This has been done in previous papers but has not been studied taking into account the detailed sequential nature of this game. We introduce a model allowing the host and parasite to make a number of decisions which will depend on various natural factors. The sequence of events begins with the host forming a nest and laying a number of eggs, followed by the possibility that a parasite bird will arrive at the nest; if it does it can choose to destroy some of the host eggs and lay one of its own. A sequence of events follows, which is broken down into two key stages; firstly the interaction between the host and the parasite adult, and secondly that between the host and the parasite chick. The final decision involves the host choosing whether to raise or abandon the chicks that are in the nest. There are certain natural parameters and probabilities which are central to these various decisions; in particular the host is generally uncertain whether parasitism has taken place, but can assess the likelihood of parasitism based upon certain cues (e.g. how many eggs remain in its nest). We then use this methodology to model two real-world interactions, that of the Reed Warbler with the Common Cuckoo and also the Yellow Warbler with the Brown-headed Cowbird. These parasites have different methods in the way they parasitize the nests of their hosts, and the hosts can in turn have different reactions to these parasites. Our model predictions generally match the real results well, and the model also makes predictions of the effect of changes in various key parameters on the type of parasitic interactions that should occur.
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Volodymyr Kharchenko
2017-03-01
Full Text Available Purpose: the aim of this study is to research applied models of air traffic controllers’ errors prevention in terminal control areas (TMA under uncertainty conditions. In this work the theoretical framework descripting safety events and errors of air traffic controllers connected with the operations in TMA is proposed. Methods: optimisation of terminal control area formal description based on the Threat and Error management model and the TMA network model of air traffic flows. Results: the human factors variables associated with safety events in work of air traffic controllers under uncertainty conditions were obtained. The Threat and Error management model application principles to air traffic controller operations and the TMA network model of air traffic flows were proposed. Discussion: Information processing context for preventing air traffic controller errors, examples of threats in work of air traffic controllers, which are relevant for TMA operations under uncertainty conditions.