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Sample records for cascade reading model

  1. DRC: a dual route cascaded model of visual word recognition and reading aloud.

    Science.gov (United States)

    Coltheart, M; Rastle, K; Perry, C; Langdon, R; Ziegler, J

    2001-01-01

    This article describes the Dual Route Cascaded (DRC) model, a computational model of visual word recognition and reading aloud. The DRC is a computational realization of the dual-route theory of reading, and is the only computational model of reading that can perform the 2 tasks most commonly used to study reading: lexical decision and reading aloud. For both tasks, the authors show that a wide variety of variables that influence human latencies influence the DRC model's latencies in exactly the same way. The DRC model simulates a number of such effects that other computational models of reading do not, but there appear to be no effects that any other current computational model of reading can simulate but that the DRC model cannot. The authors conclude that the DRC model is the most successful of the existing computational models of reading.

  2. Nonword reading: comparing dual-route cascaded and connectionist dual-process models with human data.

    Science.gov (United States)

    Pritchard, Stephen C; Coltheart, Max; Palethorpe, Sallyanne; Castles, Anne

    2012-10-01

    Two prominent dual-route computational models of reading aloud are the dual-route cascaded (DRC) model, and the connectionist dual-process plus (CDP+) model. While sharing similarly designed lexical routes, the two models differ greatly in their respective nonlexical route architecture, such that they often differ on nonword pronunciation. Neither model has been appropriately tested for nonword reading pronunciation accuracy to date. We argue that empirical data on the nonword reading pronunciation of people is the ideal benchmark for testing. Data were gathered from 45 Australian-English-speaking psychology undergraduates reading aloud 412 nonwords. To provide contrast between the models, the nonwords were chosen specifically because DRC and CDP+ disagree on their pronunciation. Both models failed to accurately match the experiment data, and both have deficiencies in nonword reading performance. However, the CDP+ model performed significantly worse than the DRC model. CDP++, the recent successor to CDP+, had improved performance over CDP+, but was also significantly worse than DRC. In addition to highlighting performance shortcomings in each model, the variety of nonword responses given by participants points to a need for models that can account for this variety.

  3. Testing for the dual-route cascade reading model in the brain: an fMRI effective connectivity account of an efficient reading style.

    Directory of Open Access Journals (Sweden)

    Jonathan Levy

    Full Text Available Neuropsychological data about the forms of acquired reading impairment provide a strong basis for the theoretical framework of the dual-route cascade (DRC model which is predictive of reading performance. However, lesions are often extensive and heterogeneous, thus making it difficult to establish precise functional anatomical correlates. Here, we provide a connective neural account in the aim of accommodating the main principles of the DRC framework and to make predictions on reading skill. We located prominent reading areas using fMRI and applied structural equation modeling to pinpoint distinct neural pathways. Functionality of regions together with neural network dissociations between words and pseudowords corroborate the existing neuroanatomical view on the DRC and provide a novel outlook on the sub-regions involved. In a similar vein, congruent (or incongruent reliance of pathways, that is reliance on the word (or pseudoword pathway during word reading and on the pseudoword (or word pathway during pseudoword reading predicted good (or poor reading performance as assessed by out-of-magnet reading tests. Finally, inter-individual analysis unraveled an efficient reading style mirroring pathway reliance as a function of the fingerprint of the stimulus to be read, suggesting an optimal pattern of cerebral information trafficking which leads to high reading performance.

  4. A Dual-Route Cascaded Model of Reading by Deaf Adults: Evidence for Grapheme to Viseme Conversion

    Science.gov (United States)

    Elliott, Eeva A.; Braun, Mario; Kuhlmann, Michael; Jacobs, Arthur M.

    2012-01-01

    There is an ongoing debate whether deaf individuals access phonology when reading, and if so, what impact the ability to access phonology might have on reading achievement. However, the debate so far has been theoretically unspecific on two accounts: (a) the phonological units deaf individuals may have of oral language have not been specified and…

  5. Self-organized model of cascade spreading

    Science.gov (United States)

    Gualdi, S.; Medo, M.; Zhang, Y.-C.

    2011-01-01

    We study simultaneous price drops of real stocks and show that for high drop thresholds they follow a power-law distribution. To reproduce these collective downturns, we propose a minimal self-organized model of cascade spreading based on a probabilistic response of the system elements to stress conditions. This model is solvable using the theory of branching processes and the mean-field approximation. For a wide range of parameters, the system is in a critical state and displays a power-law cascade-size distribution similar to the empirically observed one. We further generalize the model to reproduce volatility clustering and other observed properties of real stocks.

  6. Self-organized model of cascade spreading

    CERN Document Server

    Gualdi, Stanislao; Zhang, Yi-Cheng

    2010-01-01

    We study simultaneous price drops of real stocks and show that for high drop thresholds they follow a power-law distribution. To reproduce these collective downturns, we propose a self-organized model of cascade spreading based on a probabilistic response of the system's elements to stress conditions. This model is solvable using the theory of branching processes and the mean-field approximation and displays a power-law cascade-size distribution-similar to the empirically observed one-over a wide range of parameters.

  7. Modeling and simulation of cascading contingencies

    Science.gov (United States)

    Zhang, Jianfeng

    This dissertation proposes a new approach to model and study cascading contingencies in large power systems. The most important contribution of the work involves the development and validation of a heuristic analytic model to assess the likelihood of cascading contingencies, and the development and validation of a uniform search strategy. We model the probability of cascading contingencies as a function of power flow and power flow changes. Utilizing logistic regression, the proposed model is calibrated using real industry data. This dissertation analyzes random search strategies for Monte Carlo simulations and proposes a new uniform search strategy based on the Metropolis-Hastings Algorithm. The proposed search strategy is capable of selecting the most significant cascading contingencies, and it is capable of constructing an unbiased estimator to provide a measure of system security. This dissertation makes it possible to reasonably quantify system security and justify security operations when economic concerns conflict with reliability concerns in the new competitive power market environment. It can also provide guidance to system operators about actions that may be taken to reduce the risk of major system blackouts. Various applications can be developed to take advantage of the quantitative security measures provided in this dissertation.

  8. Transonic Cascade Measurements to Support Analytical Modeling

    Science.gov (United States)

    2007-11-02

    RECEIVED JUL 0 12005 FINAL REPORT FOR: AFOSR GRANT F49260-02-1-0284 TRANSONIC CASCADE MEASUREMENTS TO SUPPORT ANALYTICAL MODELING Paul A. Durbin ...PAD); 650-723-1971 (JKE) durbin @vk.stanford.edu; eaton@vk.stanford.edu submitted to: Attn: Dr. John Schmisseur Air Force Office of Scientific Research...both spline and control points for subsequent wall shape definitions. An algebraic grid generator was used to generate the grid for the blade-wall

  9. Mixtures of multiplicative cascade models in geochemistry

    Directory of Open Access Journals (Sweden)

    F. P. Agterberg

    2007-05-01

    Full Text Available Multifractal modeling of geochemical map data can help to explain the nature of frequency distributions of element concentration values for small rock samples and their spatial covariance structure. Useful frequency distribution models are the lognormal and Pareto distributions which plot as straight lines on logarithmic probability and log-log paper, respectively. The model of de Wijs is a simple multiplicative cascade resulting in discrete logbinomial distribution that closely approximates the lognormal. In this model, smaller blocks resulting from dividing larger blocks into parts have concentration values with constant ratios that are scale-independent. The approach can be modified by adopting random variables for these ratios. Other modifications include a single cascade model with ratio parameters that depend on magnitude of concentration value. The Turcotte model, which is another variant of the model of de Wijs, results in a Pareto distribution. Often a single straight line on logarithmic probability or log-log paper does not provide a good fit to observed data and two or more distributions should be fitted. For example, geochemical background and anomalies (extremely high values have separate frequency distributions for concentration values and for local singularity coefficients. Mixtures of distributions can be simulated by adding the results of separate cascade models. Regardless of properties of background, an unbiased estimate can be obtained of the parameter of the Pareto distribution characterizing anomalies in the upper tail of the element concentration frequency distribution or lower tail of the local singularity distribution. Computer simulation experiments and practical examples are used to illustrate the approach.

  10. Nonlinear modeling of thermoacoustically driven energy cascade

    Science.gov (United States)

    Gupta, Prateek; Scalo, Carlo; Lodato, Guido

    2016-11-01

    We present an investigation of nonlinear energy cascade in thermoacoustically driven high-amplitude oscillations, from the initial weakly nonlinear regime to the shock wave dominated limit cycle. We develop a first principle based quasi-1D model for nonlinear wave propagation in a canonical minimal unit thermoacoustic device inspired by the experimental setup of Biwa et al.. Retaining up to quadratic nonlinear terms in the governing equations, we develop model equations for nonlinear wave propagation in the proximity of differentially heated no-slip boundaries. Furthermore, we discard the effects of acoustic streaming in the present study and focus on nonlinear energy cascade due to high amplitude wave propagation. Our model correctly predicts the observed exponential growth of the thermoacoustically amplified second harmonic, as well as the energy transfer rate to higher harmonics causing wave steepening. Moreover, we note that nonlinear coupling of local pressure with heat transfer reduces thermoacoustic amplification gradually thus causing the system to reach limit cycle exhibiting shock waves. Throughout, we verify the results from the quasi-1D model with fully compressible Navier-Stokes simulations.

  11. Damped trophic cascades driven by fishing in model marine ecosystems

    DEFF Research Database (Denmark)

    Andersen, Ken Haste; Pedersen, Martin

    2010-01-01

    that fishing does not change the overall slope of the size spectrum, but depletes the largest individuals and induces trophic cascades. A trophic cascade can propagate both up and down in trophic levels driven by a combination of changes in predation mortality and food limitation. The cascade is damped...... cascade triggered by the removal of top predators. Here we use a novel size- and trait-based model to explore how marine ecosystems might react to perturbations from different types of fishing pressure. The model explicitly resolves the whole life history of fish, from larvae to adults. The results show...

  12. A stochastic model of cascades in 2D turbulence

    CERN Document Server

    Ditlevsen, Peter D

    2012-01-01

    The dual cascade of energy and enstrophy in 2D turbulence cannot easily be understood in terms of an analog to the Richardson-Kolmogorov scenario describing the energy cascade in 3D turbulence. The coherent up- and downscale fluxes points to non-locality of interactions in spectral space, and thus the specific spatial structure of the flow could be important. Shell models, which lack spacial structure and have only local interactions in spectral space, indeed fail in reproducing the correct scaling for the inverse cascade of energy. In order to exclude the possibility that non-locality of interactions in spectral space is crucial for the dual cascade, we introduce a stochastic spectral model of the cascades which is local in spectral space and which shows the correct scaling for both the direct enstrophy - and the inverse energy cascade.

  13. RECONFIGURING POWER SYSTEMS TO MINIMIZE CASCADING FAILURES: MODELS AND ALGORITHMS

    Energy Technology Data Exchange (ETDEWEB)

    Bienstock, Daniel

    2014-04-11

    the main goal of this project was to develop new scientific tools, based on optimization techniques, with the purpose of controlling and modeling cascading failures of electrical power transmission systems. We have developed a high-quality tool for simulating cascading failures. The problem of how to control a cascade was addressed, with the aim of stopping the cascade with a minimum of load lost. Yet another aspect of cascade is the investigation of which events would trigger a cascade, or more appropriately the computation of the most harmful initiating event given some constraint on the severity of the event. One common feature of the cascade models described (indeed, of several of the cascade models found in the literature) is that we study thermally-induced line tripping. We have produced a study that accounts for exogenous randomness (e.g. wind and ambient temperature) that could affect the thermal behavior of a line, with a focus on controlling the power flow of the line while maintaining safe probability of line overload. This was done by means of a rigorous analysis of a stochastic version of the heat equation. we incorporated a model of randomness in the behavior of wind power output; again modeling an OPF-like problem that uses chance-constraints to maintain low probability of line overloads; this work has been continued so as to account for generator dynamics as well.

  14. Model for cascading failures in congested Internet

    Institute of Scientific and Technical Information of China (English)

    Jian WANG; Yan-heng LIU; Jian-qi ZHU; Yu JIAO

    2008-01-01

    Cascading failures often occur in congested networks such as the Internet. A cascading failure can be described as a three-phase process: generation, diffusion, and dissipation of the congestion. In this account, we present a function that represents the extent of congestion on a given node. This approach is different from existing functions based on betweenness centrality. By introducing the concept of 'delay time', we designate an intergradation between permanent removal and nouremoval. We also construct an evaluation function of network efficiency, based on congestion, which measures the damage caused by cascading failures. Finally, we investigate the effects of network structure and size, delay time, processing ability and packet generation speed on congestion propagation. Also, we uncover the relationship between the cascade dynamics and some properties of the network such as structure and size.

  15. Dynamic Modeling of Cascading Failure in Power Systems

    CERN Document Server

    Song, Jiajia; Ghanavati, Goodarz; Hines, Paul D H

    2014-01-01

    The modeling of cascading failure in power systems is difficult because of the many different mechanisms involved; no single model captures all of these mechanisms. Understanding the relative importance of these different mechanisms is an important step in choosing which mechanisms need to be modeled for particular types of cascading failure analysis. This work presents a dynamic simulation model of both power networks and protection systems, which can simulate a wider variety of cascading outage mechanisms, relative to existing quasi-steady state (QSS) models. The model allows one to test the impact of different load models and protections on cascading outage sizes. This paper describes each module of the developed dynamic model and demonstrates how different mechanisms interact. In order to test the model we simulated a batch of randomly selected $N-2$ contingencies for several different static load configurations, and found that the distribution of blackout sizes and event lengths from the proposed dynamic...

  16. A modeling framework for system restoration from cascading failures.

    Science.gov (United States)

    Liu, Chaoran; Li, Daqing; Zio, Enrico; Kang, Rui

    2014-01-01

    System restoration from cascading failures is an integral part of the overall defense against catastrophic breakdown in networked critical infrastructures. From the outbreak of cascading failures to the system complete breakdown, actions can be taken to prevent failure propagation through the entire network. While most analysis efforts have been carried out before or after cascading failures, restoration during cascading failures has been rarely studied. In this paper, we present a modeling framework to investigate the effects of in-process restoration, which depends strongly on the timing and strength of the restoration actions. Furthermore, in the model we also consider additional disturbances to the system due to restoration actions themselves. We demonstrate that the effect of restoration is also influenced by the combination of system loading level and restoration disturbance. Our modeling framework will help to provide insights on practical restoration from cascading failures and guide improvements of reliability and resilience of actual network systems.

  17. Rate equation modelling and investigation of quantum cascade detector characteristics

    Science.gov (United States)

    Saha, Sumit; Kumar, Jitendra

    2016-10-01

    A simple precise transport model has been proposed using rate equation approach for the characterization of a quantum cascade detector. The resonant tunneling transport is incorporated in the rate equation model through a resonant tunneling current density term. All the major scattering processes are included in the rate equation model. The effect of temperature on the quantum cascade detector characteristics has been examined considering the temperature dependent band parameters and the carrier scattering processes. Incorporation of the resonant tunneling process in the rate equation model improves the detector performance appreciably and reproduces the detector characteristics within experimental accuracy.

  18. Modeling of Bit Error Rate in Cascaded 2R Regenerators

    DEFF Research Database (Denmark)

    Öhman, Filip; Mørk, Jesper

    2006-01-01

    This paper presents a simple and efficient model for estimating the bit error rate in a cascade of optical 2R-regenerators. The model includes the influences of of amplifier noise, finite extinction ratio and nonlinear reshaping. The interplay between the different signal impairments and the rege......This paper presents a simple and efficient model for estimating the bit error rate in a cascade of optical 2R-regenerators. The model includes the influences of of amplifier noise, finite extinction ratio and nonlinear reshaping. The interplay between the different signal impairments...

  19. A Cascading Model Of An Active Magnetic Regenerator System

    DEFF Research Database (Denmark)

    Tahavori, M.; Filonenko, K.; Veje, C. T.;

    2016-01-01

    In recent years, significant amounts of studies have been done on modeling and analysis of active magnetic regenerators (AMRs). Depending on the AMR geometry and the magnetocaloric material being modeled, the AMR may not be able to provide the required performance demanded by practical applications....... Some AMR models in the literature predict high performance but with relatively low temperature spans at either end of the AMR. Therefore, they may not be sufficient for practical applications, such as providing the heat exchanger temperature spans required for residential and commercial space air...... conditioning. To remedy this, one solution is cascading of multiple single layer AMRs. In this work, a cascading AMR model is presented and studied. In a cascade configuration, N number of single layer AMRs are connected. The results show that higher hot and cold side temperature differences may be achieved...

  20. Up and down cascades: three-dimensional magnetic field model.

    Science.gov (United States)

    Blanter, E M; Shnirman, M G; Le Mouël, J L

    2002-06-01

    In our previous works we already have proposed a two-dimensional model of geodynamo. Now we use the same approach to build a three-dimensional self-excited geodynamo model that generates a large scale magnetic field from whatever small initial field, using the up and down cascade effects of a multiscale turbulent system of cyclones. The multiscale system of turbulent cyclones evolves in six domains of an equatorial cylindrical layer of the core. The appearance of new cyclones is realized by two cascades: a turbulent direct cascade and an inverse cascade of coupling of similar cyclones. The interaction between the different domains is effected through a direct cascade parameter which is essential for the statistics of the long-life symmetry breaking. Generation of the secondary magnetic field results from the interaction of the components of the primary magnetic field with the turbulent cyclones. The amplification of the magnetic field is due to the transfer of energy from the turbulent helical motion to the generated magnetic field. The model demonstrates a phase transition through the parameter characterizing this energy transfer. In the supercritical domain we obtain long-term intervals of constant polarity (chrons) and quick reversals; relevant time constants agree with paleomagnetic observations. Possible application of the model to the study of the geometrical structure of the geomagnetic field (and briefly other planetary fields) is discussed.

  1. One-dimensional hydrodynamic model generating turbulent cascade

    CERN Document Server

    Matsumoto, Takeshi

    2016-01-01

    As a minimal mathematical model generating cascade analogous to that of the Navier-Stokes turbulence in the inertial range, we propose a one-dimensional partial-differential-equation model that conserves the integral of the squared vorticity analogue (enstrophy) in the inviscid case. With a large-scale forcing and small viscosity, we find numerically that the model exhibits the enstrophy cascade, the broad energy spectrum with a sizable correction to the dimensional-analysis prediction, peculiar intermittency and self-similarity in the dynamical system structure.

  2. One-dimensional hydrodynamic model generating a turbulent cascade

    Science.gov (United States)

    Matsumoto, Takeshi; Sakajo, Takashi

    2016-05-01

    As a minimal mathematical model generating cascade analogous to that of the Navier-Stokes turbulence in the inertial range, we propose a one-dimensional partial-differential-equation model that conserves the integral of the squared vorticity analog (enstrophy) in the inviscid case. With a large-scale random forcing and small viscosity, we find numerically that the model exhibits the enstrophy cascade, the broad energy spectrum with a sizable correction to the dimensional-analysis prediction, peculiar intermittency, and self-similarity in the dynamical system structure.

  3. Robustness of Power-law Behavior in Cascading Failure Models

    CERN Document Server

    Sloothaak, F; Zwart, A P

    2016-01-01

    Inspired by reliability issues in electric transmission networks, we use a probabilistic approach to study the occurrence of large failures in a stylized cascading failure model. In this model, lines have random capacities that initially meet the load demands imposed on the network. Every single line failure changes the load distribution in the surviving network, possibly causing further lines to become overloaded and trip as well. An initial single line failure can therefore potentially trigger massive cascading effects, and in this paper we measure the risk of such cascading events by the probability that the number of failed lines exceeds a certain large threshold. Under particular critical conditions, the exceedance probability follows a power-law distribution, implying a significant risk of severe failures. We examine the robustness of the power-law behavior by exploring under which assumptions this behavior prevails.

  4. Feigenbaum Cascade of Discrete Breathers in a Model of DNA

    CERN Document Server

    Maniadis, P; Bishop, A R; Rasmussen, K \\O

    2010-01-01

    We demonstrate that period-doubled discrete breathers appear from the anti-continuum limit of the driven Peyrard-Bishop-Dauxois model of DNA. These novel breathers result from a stability overlap between sub-harmonic solutions of the driven Morse oscillator. Sub-harmonic breathers exist whenever a stability overlap is present within the Feigenbaum cascade to chaos and therefore an entire cascade of such breathers exists. This phenomenon is present in any driven lattice where the on-site potential admits sub-harmonic solutions. In DNA these breathers may have ramifications for cellular gene expression.

  5. A psychological cascade model for persisting voice problems in teachers

    NARCIS (Netherlands)

    de Jong, FICRS; Cornelis, BE; Wuyts, FL; Kooijman, PGC; Schutte, HK; Oudes, MJ; Graamans, K

    2003-01-01

    In 76 teachers with persisting voice problems, the maintaining factors and coping strategies were examined. Physical, functional, psychological and socioeconomic factors were assessed. A parallel was drawn to a psychological cascade model designed for patients with chronic back pain. The majority of

  6. A psychological cascade model for persisting voice problems in teachers

    NARCIS (Netherlands)

    de Jong, FICRS; Cornelis, BE; Wuyts, FL; Kooijman, PGC; Schutte, HK; Oudes, MJ; Graamans, K

    2003-01-01

    In 76 teachers with persisting voice problems, the maintaining factors and coping strategies were examined. Physical, functional, psychological and socioeconomic factors were assessed. A parallel was drawn to a psychological cascade model designed for patients with chronic back pain. The majority of

  7. Modeling Events with Cascades of Poisson Processes

    CERN Document Server

    Simma, Aleksandr

    2012-01-01

    We present a probabilistic model of events in continuous time in which each event triggers a Poisson process of successor events. The ensemble of observed events is thereby modeled as a superposition of Poisson processes. Efficient inference is feasible under this model with an EM algorithm. Moreover, the EM algorithm can be implemented as a distributed algorithm, permitting the model to be applied to very large datasets. We apply these techniques to the modeling of Twitter messages and the revision history of Wikipedia.

  8. Threshold model of cascades in temporal networks

    CERN Document Server

    Karimi, Fariba

    2012-01-01

    Threshold models try to explain the consequences of social influence like the spread of fads and opinions. Along with models of epidemics, they constitute a major theoretical framework of social spreading processes. In threshold models on static networks, an individual changes her state if a certain fraction of her neighbors has done the same. When there are strong correlations in the temporal aspects of contact patterns, it is useful to represent the system as a temporal network. In such a system, not only contacts but also the time of the contacts are represented explicitly. There is a consensus that bursty temporal patterns slow down disease spreading. However, as we will see, this is not a universal truth for threshold models. In this work, we propose an extension of Watts' classic threshold model to temporal networks. We do this by assuming that an agent is influenced by contacts which lie a certain time into the past. I.e., the individuals are affected by contacts within a time window. In addition to th...

  9. Cascades in the Threshold Model for varying system sizes

    Science.gov (United States)

    Karampourniotis, Panagiotis; Sreenivasan, Sameet; Szymanski, Boleslaw; Korniss, Gyorgy

    2015-03-01

    A classical model in opinion dynamics is the Threshold Model (TM) aiming to model the spread of a new opinion based on the social drive of peer pressure. Under the TM a node adopts a new opinion only when the fraction of its first neighbors possessing that opinion exceeds a pre-assigned threshold. Cascades in the TM depend on multiple parameters, such as the number and selection strategy of the initially active nodes (initiators), and the threshold distribution of the nodes. For a uniform threshold in the network there is a critical fraction of initiators for which a transition from small to large cascades occurs, which for ER graphs is largerly independent of the system size. Here, we study the spread contribution of each newly assigned initiator under the TM for different initiator selection strategies for synthetic graphs of various sizes. We observe that for ER graphs when large cascades occur, the spread contribution of the added initiator on the transition point is independent of the system size, while the contribution of the rest of the initiators converges to zero at infinite system size. This property is used for the identification of large transitions for various threshold distributions. Supported in part by ARL NS-CTA, ARO, ONR, and DARPA.

  10. An Active Reading Model for English Learners

    Institute of Scientific and Technical Information of China (English)

    徐岩; 张琳

    2008-01-01

    Acuve reading makes a reader interact with the text.It promotes learning,Acuve reading model actually presents six reading strategies that teachers should consider when teaching English to a class of non-native speakers.That guides both teachers and students in their working and learning.

  11. Cascade Failure in a Phase Model of Power Grids

    Science.gov (United States)

    Sakaguchi, Hidetsugu; Matsuo, Tatsuma

    2012-07-01

    We propose a phase model to study cascade failure in power grids composed of generators and loads. If the power demand is below a critical value, the model system of power grids maintains the standard frequency by feedback control. On the other hand, if the power demand exceeds the critical value, an electric failure occurs via step out (loss of synchronization) or voltage collapse. The two failures are incorporated as two removal rules of generator nodes and load nodes. We perform direct numerical simulation of the phase model on a square lattice and a scale-free network and compare the results with a mean-field approximation.

  12. Cascaded process model based control: packed absorption column application.

    Science.gov (United States)

    Govindarajan, Anand; Jayaraman, Suresh Kumar; Sethuraman, Vijayalakshmi; Raul, Pramod R; Rhinehart, R Russell

    2014-03-01

    Nonlinear, adaptive, process-model based control is demonstrated in a cascaded single-input-single-output mode for pressure drop control in a pilot-scale packed absorption column. The process is shown to be nonlinear. Control is demonstrated in both servo and regulatory modes, for no wind-up in a constrained situation, and for bumpless transfer. Model adaptation is demonstrated and shown to provide process insight. The application procedure is revealed as a design guide to aid others in implementing process-model based control.

  13. Boolean Models of Biological Processes Explain Cascade-Like Behavior.

    Science.gov (United States)

    Chen, Hao; Wang, Guanyu; Simha, Rahul; Du, Chenghang; Zeng, Chen

    2016-01-29

    Biological networks play a key role in determining biological function and therefore, an understanding of their structure and dynamics is of central interest in systems biology. In Boolean models of such networks, the status of each molecule is either "on" or "off" and along with the molecules interact with each other, their individual status changes from "on" to "off" or vice-versa and the system of molecules in the network collectively go through a sequence of changes in state. This sequence of changes is termed a biological process. In this paper, we examine the common perception that events in biomolecular networks occur sequentially, in a cascade-like manner, and ask whether this is likely to be an inherent property. In further investigations of the budding and fission yeast cell-cycle, we identify two generic dynamical rules. A Boolean system that complies with these rules will automatically have a certain robustness. By considering the biological requirements in robustness and designability, we show that those Boolean dynamical systems, compared to an arbitrary dynamical system, statistically present the characteristics of cascadeness and sequentiality, as observed in the budding and fission yeast cell- cycle. These results suggest that cascade-like behavior might be an intrinsic property of biological processes.

  14. Fix-point Multiplier Distributions in Discrete Turbulent Cascade Models

    CERN Document Server

    Jouault, B; Lipa, P

    1998-01-01

    One-point time-series measurements limit the observation of three-dimensional fully developed turbulence to one dimension. For one-dimensional models, like multiplicative branching processes, this implies that the energy flux from large to small scales is not conserved locally. This then renders the random weights used in the cascade curdling to be different from the multipliers obtained from a backward averaging procedure. The resulting multiplier distributions become solutions of a fix-point problem. With a further restoration of homogeneity, all observed correlations between multipliers in the energy dissipation field can be understood in terms of simple scale-invariant multiplicative branching processes.

  15. Modelling of GaN quantum dot terahertz cascade laser

    Science.gov (United States)

    Asgari, A.; Khorrami, A. A.

    2013-03-01

    In this paper GaN based spherical quantum dot cascade lasers has been modelled, where the generation of the terahertz waves are obtained. The Schrödinger, Poisson, and the laser rate equations have been solved self-consistently including all dominant physical effects such as piezoelectric and spontaneous polarization in nitride-based QDs and the effects of the temperature. The exact value of the energy levels, the wavefunctions, the lifetimes of electron levels, and the lasing frequency are calculated. Also the laser parameters such as the optical gain, the output power and the threshold current density have been calculated at different temperatures and applied electric fields.

  16. Emotion: Appraisal-coping model for the "Cascades" problem

    CERN Document Server

    Mahboub, Karim; Bertelle, Cyrille; Jay, Véronique

    2009-01-01

    Modelling emotion has become a challenge nowadays. Therefore, several models have been produced in order to express human emotional activity. However, only a few of them are currently able to express the close relationship existing between emotion and cognition. An appraisal-coping model is presented here, with the aim to simulate the emotional impact caused by the evaluation of a particular situation (appraisal), along with the consequent cognitive reaction intended to face the situation (coping). This model is applied to the "Cascades" problem, a small arithmetical exercise designed for ten-year-old pupils. The goal is to create a model corresponding to a child's behaviour when solving the problem using his own strategies.

  17. Emotional intelligence: an integrative meta-analysis and cascading model.

    Science.gov (United States)

    Joseph, Dana L; Newman, Daniel A

    2010-01-01

    Research and valid practice in emotional intelligence (EI) have been impeded by lack of theoretical clarity regarding (a) the relative roles of emotion perception, emotion understanding, and emotion regulation facets in explaining job performance; (b) conceptual redundancy of EI with cognitive intelligence and Big Five personality; and (c) application of the EI label to 2 distinct sets of constructs (i.e., ability-based EI and mixed-based EI). In the current article, the authors propose and then test a theoretical model that integrates these factors. They specify a progressive (cascading) pattern among ability-based EI facets, in which emotion perception must causally precede emotion understanding, which in turn precedes conscious emotion regulation and job performance. The sequential elements in this progressive model are believed to selectively reflect Conscientiousness, cognitive ability, and Neuroticism, respectively. "Mixed-based" measures of EI are expected to explain variance in job performance beyond cognitive ability and personality. The cascading model of EI is empirically confirmed via meta-analytic data, although relationships between ability-based EI and job performance are shown to be inconsistent (i.e., EI positively predicts performance for high emotional labor jobs and negatively predicts performance for low emotional labor jobs). Gender and race differences in EI are also meta-analyzed. Implications for linking the EI fad in personnel selection to established psychological theory are discussed.

  18. Monte Carlo Modeling Electronuclear Processes in Cascade Subcritical Reactor

    CERN Document Server

    Bznuni, S A; Zhamkochyan, V M; Polyanskii, A A; Sosnin, A N; Khudaverdian, A G

    2000-01-01

    Accelerator driven subcritical cascade reactor composed of the main thermal neutron reactor constructed analogous to the core of the VVER-1000 reactor and a booster-reactor, which is constructed similar to the core of the BN-350 fast breeder reactor, is taken as a model example. It is shown by means of Monte Carlo calculations that such system is a safe energy source (k_{eff}=0.94-0.98) and it is capable of transmuting produced radioactive wastes (neutron flux density in the thermal zone is PHI^{max} (r,z)=10^{14} n/(cm^{-2} s^{-1}), neutron flux in the fast zone is respectively equal PHI^{max} (r,z)=2.25 cdot 10^{15} n/(cm^{-2} s^{-1}) if the beam current of the proton accelerator is k_{eff}=0.98 and I=5.3 mA). Suggested configuration of the "cascade" reactor system essentially reduces the requirements on the proton accelerator current.

  19. Toward Holistic Scene Understanding: Feedback Enabled Cascaded Classification Models.

    Science.gov (United States)

    Li, Congcong; Kowdle, Adarsh; Saxena, Ashutosh; Chen, Tsuhan

    2012-07-01

    Scene understanding includes many related subtasks, such as scene categorization, depth estimation, object detection, etc. Each of these subtasks is often notoriously hard, and state-of-the-art classifiers already exist for many of them. These classifiers operate on the same raw image and provide correlated outputs. It is desirable to have an algorithm that can capture such correlation without requiring any changes to the inner workings of any classifier. We propose Feedback Enabled Cascaded Classification Models (FE-CCM), that jointly optimizes all the subtasks while requiring only a "black box" interface to the original classifier for each subtask. We use a two-layer cascade of classifiers, which are repeated instantiations of the original ones, with the output of the first layer fed into the second layer as input. Our training method involves a feedback step that allows later classifiers to provide earlier classifiers information about which error modes to focus on. We show that our method significantly improves performance in all the subtasks in the domain of scene understanding, where we consider depth estimation, scene categorization, event categorization, object detection, geometric labeling, and saliency detection. Our method also improves performance in two robotic applications: an object-grasping robot and an object-finding robot.

  20. Calibration of a modified Sierra Model 235 slotted cascade impactor

    Energy Technology Data Exchange (ETDEWEB)

    Knuth, R.H.

    1979-07-01

    For measurements of ore dust in uranium concentrating mills, a Sierra Model 235 slotted cascade impactor was calibrated at a flow rate of .21 m/sup 3//min, using solid monodisperse particles and an impaction surface of Whatman No. 41 filter paper soaked in mineral oil. The reduction from the impactor's design flow rate of 1.13 m/sup 3//min (40 cfm) to 0.21 m/sup 3//min (7.5 cfm) increased the stage cut-off diameters by an average factor of 2.3, a necessary adjustment because of the anticipated large particle sizes of ore dust. The underestimation of mass median diameters, often caused by the rebound and reentrainment of solid particles from dry impaction surfaces, was virtually eliminated by using the oiled Whatman No. 41 impaction surface. Observations of satisfactory performance in the laboratory were verified by tests of the impactor in ore mills.

  1. Modeling Collisional Cascades In Debris Disks: The Numerical Method

    CERN Document Server

    Gaspar, Andras; Ozel, Feryal; Rieke, George H; Cooney, Alan

    2011-01-01

    We develop a new numerical algorithm to model collisional cascades in debris disks. Because of the large dynamical range in particle masses, we solve the integro-differential equations describing erosive and catastrophic collisions in a particle-in-a-box approach, while treating the orbital dynamics of the particles in an approximate fashion. We employ a new scheme for describing erosive (cratering) collisions that yields a continuous set of outcomes as a function of colliding masses. We demonstrate the stability and convergence characteristics of our algorithm and compare it with other treatments. We show that incorporating the effects of erosive collisions results in a decay of the particle distribution that is significantly faster than with purely catastrophic collisions.

  2. MODELING COLLISIONAL CASCADES IN DEBRIS DISKS: THE NUMERICAL METHOD

    Energy Technology Data Exchange (ETDEWEB)

    Gaspar, Andras; Psaltis, Dimitrios; Oezel, Feryal; Rieke, George H.; Cooney, Alan, E-mail: agaspar@as.arizona.edu, E-mail: dpsaltis@as.arizona.edu, E-mail: fozel@as.arizona.edu, E-mail: grieke@as.arizona.edu, E-mail: acooney@physics.arizona.edu [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)

    2012-04-10

    We develop a new numerical algorithm to model collisional cascades in debris disks. Because of the large dynamical range in particle masses, we solve the integro-differential equations describing erosive and catastrophic collisions in a particle-in-a-box approach, while treating the orbital dynamics of the particles in an approximate fashion. We employ a new scheme for describing erosive (cratering) collisions that yields a continuous set of outcomes as a function of colliding masses. We demonstrate the stability and convergence characteristics of our algorithm and compare it with other treatments. We show that incorporating the effects of erosive collisions results in a decay of the particle distribution that is significantly faster than with purely catastrophic collisions.

  3. Testing the inhibitory cascade model in Mesozoic and Cenozoic mammaliaforms

    Science.gov (United States)

    2013-01-01

    Background Much of the current research in the growing field of evolutionary development concerns relating developmental pathways to large-scale patterns of morphological evolution, with developmental constraints on variation, and hence diversity, a field of particular interest. Tooth morphology offers an excellent model system for such ‘evo-devo’ studies, because teeth are well preserved in the fossil record, and are commonly used in phylogenetic analyses and as ecological proxies. Moreover, tooth development is relatively well studied, and has provided several testable hypotheses of developmental influences on macroevolutionary patterns. The recently-described Inhibitory Cascade (IC) Model provides just such a hypothesis for mammalian lower molar evolution. Derived from experimental data, the IC Model suggests that a balance between mesenchymal activators and molar-derived inhibitors determines the size of the immediately posterior molar, predicting firstly that molars either decrease in size along the tooth row, or increase in size, or are all of equal size, and secondly that the second lower molar should occupy one third of lower molar area. Here, we tested the IC Model in a large selection of taxa from diverse extant and fossil mammalian groups, ranging from the Middle Jurassic (~176 to 161 Ma) to the Recent. Results Results show that most taxa (~65%) fell within the predicted areas of the Inhibitory Cascade Model. However, members of several extinct groups fell into the regions where m2 was largest, or rarely, smallest, including the majority of the polyphyletic “condylarths”. Most Mesozoic mammals fell near the centre of the space with equality of size in all three molars. The distribution of taxa was significantly clustered by diet and by phylogenetic group. Conclusions Overall, the IC Model was supported as a plesiomorphic developmental system for Mammalia, suggesting that mammal tooth size has been subjected to this developmental constraint at

  4. A cascaded neuro-computational model for spoken word recognition

    Science.gov (United States)

    Hoya, Tetsuya; van Leeuwen, Cees

    2010-03-01

    In human speech recognition, words are analysed at both pre-lexical (i.e., sub-word) and lexical (word) levels. The aim of this paper is to propose a constructive neuro-computational model that incorporates both these levels as cascaded layers of pre-lexical and lexical units. The layered structure enables the system to handle the variability of real speech input. Within the model, receptive fields of the pre-lexical layer consist of radial basis functions; the lexical layer is composed of units that perform pattern matching between their internal template and a series of labels, corresponding to the winning receptive fields in the pre-lexical layer. The model adapts through self-tuning of all units, in combination with the formation of a connectivity structure through unsupervised (first layer) and supervised (higher layers) network growth. Simulation studies show that the model can achieve a level of performance in spoken word recognition similar to that of a benchmark approach using hidden Markov models, while enabling parallel access to word candidates in lexical decision making.

  5. A simple model of global cascades on random networks

    Science.gov (United States)

    Watts, Duncan J.

    2002-04-01

    The origin of large but rare cascades that are triggered by small initial shocks is a phenomenon that manifests itself as diversely as cultural fads, collective action, the diffusion of norms and innovations, and cascading failures in infrastructure and organizational networks. This paper presents a possible explanation of this phenomenon in terms of a sparse, random network of interacting agents whose decisions are determined by the actions of their neighbors according to a simple threshold rule. Two regimes are identified in which the network is susceptible to very large cascadesherein called global cascadesthat occur very rarely. When cascade propagation is limited by the connectivity of the network, a power law distribution of cascade sizes is observed, analogous to the cluster size distribution in standard percolation theory and avalanches in self-organized criticality. But when the network is highly connected, cascade propagation is limited instead by the local stability of the nodes themselves, and the size distribution of cascades is bimodal, implying a more extreme kind of instability that is correspondingly harder to anticipate. In the first regime, where the distribution of network neighbors is highly skewed, it is found that the most connected nodes are far more likely than average nodes to trigger cascades, but not in the second regime. Finally, it is shown that heterogeneity plays an ambiguous role in determining a system's stability: increasingly heterogeneous thresholds make the system more vulnerable to global cascades; but an increasingly heterogeneous degree distribution makes it less vulnerable.

  6. Hybrid Model for Cascading Outage in a Power System: A Numerical Study

    OpenAIRE

    Susuki, Yoshihiko; Takatsuji, Yu; Hikihara, Takashi

    2009-01-01

    Analysis of cascading outages in power systems is important for understanding why large blackouts emerge and how to prevent them. Cascading outages are complex dynamics of power systems, and one cause of them is the interaction between swing dynamics of synchronous machines and protection operation of relays and circuit breakers. This paper uses hybrid dynamical systems as a mathematical model for cascading outages caused by the interaction. Hybrid dynamical systems can combine families of fl...

  7. Decision-making model for risk management of cascade hydropower stations

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In a medium-term electricity market,in order to reduce the risks of price and inflow uncertainties, the cascade hydropower stations may use the options contract with electricity supply companies. A profit-based model for risk management of cascade hydropower stations in the medium-term electricity market is presented. The objective function is profit maximization of cascade hydropower stations. In order to avoid the risks of price and inflow uncertainties, two different risk-aversion constraints: a minimum ...

  8. Developmental Cascade Model for Adolescent Substance Use from Infancy to Late Adolescence

    Science.gov (United States)

    Eiden, Rina D.; Lessard, Jared; Colder, Craig R.; Livingston, Jennifer; Casey, Meghan; Leonard, Kenneth E.

    2016-01-01

    A developmental cascade model for adolescent substance use beginning in infancy was examined in a sample of children with alcoholic and nonalcoholic parents. The model examined the role of parents' alcohol diagnoses, depression and antisocial behavior in a cascading process of risk via 3 major hypothesized pathways: first, via parental…

  9. Developmental Cascade Model for Adolescent Substance Use from Infancy to Late Adolescence

    Science.gov (United States)

    Eiden, Rina D.; Lessard, Jared; Colder, Craig R.; Livingston, Jennifer; Casey, Meghan; Leonard, Kenneth E.

    2016-01-01

    A developmental cascade model for adolescent substance use beginning in infancy was examined in a sample of children with alcoholic and nonalcoholic parents. The model examined the role of parents' alcohol diagnoses, depression and antisocial behavior in a cascading process of risk via 3 major hypothesized pathways: first, via parental…

  10. Discontinuous Transition of a Multistage Independent Cascade Model on Networks

    CERN Document Server

    Hasegawa, Takehisa

    2012-01-01

    We study a multistage independent cascade (MIC) model in complex networks. This model is parameterized by two probabilities: T1 is the probability that a node adopting a fad increases the awareness of a neighboring susceptible node until it abandons the fad, and T2 is the probability that an adopter directly causes a susceptible node to adopt the fad. We formulate a framework of tree approximation for the MIC model on an uncorrelated network with an arbitrary given degree distribution. As an application, we study this model on a random regular network with degree k=6 to show that it has a rich phase diagram including continuous and discontinuous transition lines for the percolation of fads as well as a continuous transition line for the percolation of susceptible nodes. In particular, the percolation transition of fads is discontinuous (continuous) when T1 is larger (smaller) than a certain value. Furthermore, the phase boundaries drastically change by assigning a finite fraction of initial adopters. We discu...

  11. Linear models of activation cascades: analytical solutions and coarse-graining of delayed signal transduction.

    Science.gov (United States)

    Beguerisse-Díaz, Mariano; Desikan, Radhika; Barahona, Mauricio

    2016-08-01

    Cellular signal transduction usually involves activation cascades, the sequential activation of a series of proteins following the reception of an input signal. Here, we study the classic model of weakly activated cascades and obtain analytical solutions for a variety of inputs. We show that in the special but important case of optimal gain cascades (i.e. when the deactivation rates are identical) the downstream output of the cascade can be represented exactly as a lumped nonlinear module containing an incomplete gamma function with real parameters that depend on the rates and length of the cascade, as well as parameters of the input signal. The expressions obtained can be applied to the non-identical case when the deactivation rates are random to capture the variability in the cascade outputs. We also show that cascades can be rearranged so that blocks with similar rates can be lumped and represented through our nonlinear modules. Our results can be used both to represent cascades in computational models of differential equations and to fit data efficiently, by reducing the number of equations and parameters involved. In particular, the length of the cascade appears as a real-valued parameter and can thus be fitted in the same manner as Hill coefficients. Finally, we show how the obtained nonlinear modules can be used instead of delay differential equations to model delays in signal transduction.

  12. Numerical Physical Mechanism and Model of Turbulent Cascades in a Barotropic Atmosphere

    Institute of Scientific and Technical Information of China (English)

    黄锋; 刘式适

    2004-01-01

    In a barotropic atmosphere,new Reynolds mean momentum equations including turbulent viscosity,dispersion,and instability are used not only to derive the KdV-Burgers-Kuramoto equation but also to analyze the physical mechanism of the cascades of energy and enstrophy.It shows that it is the effects of dispersion and instability that result in the inverse cascade.Then based on the conservation laws of the energy and enstrophy,a cascade model is put forward and the processes of the cascades are described.

  13. Mesoscopic Modeling of Blood Clotting: Coagulation Cascade and Platelets Adhesion

    Science.gov (United States)

    Yazdani, Alireza; Li, Zhen; Karniadakis, George

    2015-11-01

    The process of clot formation and growth at a site on a blood vessel wall involve a number of multi-scale simultaneous processes including: multiple chemical reactions in the coagulation cascade, species transport and flow. To model these processes we have incorporated advection-diffusion-reaction (ADR) of multiple species into an extended version of Dissipative Particle Dynamics (DPD) method which is considered as a coarse-grained Molecular Dynamics method. At the continuum level this is equivalent to the Navier-Stokes equation plus one advection-diffusion equation for each specie. The chemistry of clot formation is now understood to be determined by mechanisms involving reactions among many species in dilute solution, where reaction rate constants and species diffusion coefficients in plasma are known. The role of blood particulates, i.e. red cells and platelets, in the clotting process is studied by including them separately and together in the simulations. An agonist-induced platelet activation mechanism is presented, while platelets adhesive dynamics based on a stochastic bond formation/dissociation process is included in the model.

  14. INTENSIVE READING: A NEW MODEL OF CLASSROOM TEACHING

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The intensive reading class should focus on students’ reading problems and the techniques they need to become efficient readers. A model of reading technique training, including attack skills at the word, sentence and discourse level, is presented.

  15. Hybrid Model for Cascading Outage in a Power System: A Numerical Study

    Science.gov (United States)

    Susuki, Yoshihiko; Takatsuji, Yu; Hikihara, Takashi

    Analysis of cascading outages in power systems is important for understanding why large blackouts emerge and how to prevent them. Cascading outages are complex dynamics of power systems, and one cause of them is the interaction between swing dynamics of synchronous machines and protection operation of relays and circuit breakers. This paper uses hybrid dynamical systems as a mathematical model for cascading outages caused by the interaction. Hybrid dynamical systems can combine families of flows describing swing dynamics with switching rules that are based on protection operation. This paper refers to data on a cascading outage in the September 2003 blackout in Italy and shows a hybrid dynamical system by which propagation of outages reproduced is consistent with the data. This result suggests that hybrid dynamical systems can provide an effective model for the analysis of cascading outages in power systems.

  16. Scanpath Based N-Gram Models for Predicting Reading Behavior

    DEFF Research Database (Denmark)

    Mishra, Abhijit; Bhattacharyya, Pushpak; Carl, Michael

    2013-01-01

    Predicting reading behavior is a difficult task. Reading behavior depends on various linguistic factors (e.g. sentence length, structural complexity etc.) and other factors (e.g individual's reading style, age etc.). Ideally, a reading model should be similar to a language model where the model i...

  17. Robustness and perturbation in the modeled cascade heart rate variability

    Science.gov (United States)

    Lin, D. C.

    2003-03-01

    In this study, numerical experiments are conducted to examine the robustness of using cascade to describe the multifractal heart rate variability (HRV) by perturbing the hierarchical time scale structure and the multiplicative rule of the cascade. It is shown that a rigid structure of the multiple time scales is not essential for the multifractal scaling in healthy HRV. So long as there exists a tree structure for the multiplication to take place, a multifractal HRV and related properties can be captured by using the cascade. But the perturbation of the multiplicative rule can lead to a qualitative change. In particular, a multifractal to monofractal HRV transition can result after the product law is perturbed to an additive one at the fast time scale. We suggest that this explains the similar HRV scaling transition in the parasympathetic nervous system blockade.

  18. Piecewise-polynomial and cascade models of predistorter for linearization of power amplifier

    OpenAIRE

    2012-01-01

    To combat non-linear signal distortions in a power amplifier we suggest using predistorter with cascade structure in which first and second nodes have piecewise-polynomial and polynomial models. On example of linearizing the Winner–Hammerstein amplifier model we demonstrate that cascade structure of predistorter improves precision of amplifier’s linearization. To simplify predistorter’s synthesis the degree of polynomial model used in first node should be moderate, while precision should be i...

  19. Experimental calibration of the mathematical model of Air Torque Position dampers with non-cascading blades

    OpenAIRE

    Bikić Siniša M.; Uzelac Dušan N.; Bukurov Maša Ž.; Radojčin Milivoj T.; Pavkov Ivan S.

    2016-01-01

    This paper is focused on the mathematical model of the Air Torque Position dampers. The mathematical model establishes a link between the velocity of air in front of the damper, position of the damper blade and the moment acting on the blade caused by the air flow. This research aims to experimentally verify the mathematical model for the damper type with non-cascading blades. Four different types of dampers with non-cascading blades were considered: single...

  20. Establishment and evaluation of operation function model for cascade hydropower station

    Directory of Open Access Journals (Sweden)

    Chang-ming JI

    2010-12-01

    Full Text Available Toward solving the actual operation problems of cascade hydropower stations under hydrologic uncertainty, this paper presents the process of extraction of statistical characteristics from long-term optimal cascade operation, and proposes a monthly operation function algorithm for the actual operation of cascade hydropower stations through the identification, processing, and screening of available information during long-term optimal operation. Applying the operation function to the cascade hydropower stations on the Jinshajiang-Yangtze River system, the modeled long-term electric generation is shown to have high precision and provide benefits. Through comparison with optimal operation, the simulation results show that the operation function proposed retains the characteristics of optimal operation. Also, the inadequacies and attribution of the algorithm are discussed based on case study, providing decision support and reference information for research on large-scale cascade operation work.

  1. Short term forecasting of surface layer wind speed using a continuous cascade model

    CERN Document Server

    Baile, Rachel; Poggi, Philippe

    2010-01-01

    This paper describes a statistical method for short-term forecasting of surface layer wind velocity amplitude relying on the notion of continuous cascades. Inspired by recent empirical findings that suggest the existence of some cascading process in the mesoscale range, we consider that wind speed can be described by a seasonal component and a fluctuating part represented by a "multifractal noise" associated with a random cascade. Performances of our model are tested on hourly wind speed series gathered at various locations in Corsica (France) and Netherlands. The obtained results show a systematic improvement of the prediction as compared to reference models like persistence or Artificial Neural Networks.

  2. The theoretical development of the cascade model excimer laser irradiation on the organ of vision

    Directory of Open Access Journals (Sweden)

    V. N. Trubilin

    2012-01-01

    Full Text Available Authors analyzed the baseline (Pershin K. B., 2000 and advanced (trubilin V. N Pozharitskii M. D., 2011 theoretical model of the cascade excimer laser effects on eyesight.the analysis indicates a lack of elaboration of issues related to the cascade of «a priori measures» aimed at medical and psycho- logical prediction «quality of life» and post-operative rehabilitation. In theory, authors suggest further improvement of the cascade model of excimer laser irradiation on the organ of vision. the proposed theoretical concepts will provide a practical matter, improvefunctional and subjective results of the excimer laser correction of refractive errors.

  3. Information cascade, Kirman's ant colony model, and kinetic Ising model

    CERN Document Server

    Hisakado, Masato

    2014-01-01

    In this paper, we discuss a voting model in which voters can obtain information from a finite number of previous voters. There exist three groups of voters: (i) digital herders and independent voters, (ii) analog herders and independent voters, and (iii) tanh-type herders. In our previous paper, we used the mean field approximation for case (i). In that study, if the reference number r is above three, phase transition occurs and the solution converges to one of the equilibria. In contrast, in the current study, the solution oscillates between the two equilibria, that is, good and bad equilibria. In this paper, we show that there is no phase transition when r is finite. If the annealing schedule is adequately slow from finite r to infinite r, the voting rate converges only to the good equilibrium. In case (ii), the state of reference votes is equivalent to that of Kirman's ant colony model, and it follows beta binomial distribution. In case (iii), we show that the model is equivalent to the finite-size kinetic...

  4. Modeling self-sustained activity cascades in socio-technical networks

    CERN Document Server

    Piedrahíta, Pablo; Moreno, Yamir; Arenas, Alex

    2013-01-01

    The ability to understand and eventually predict the emergence of information and activation cascades in social networks is core to complex socio-technical systems research. However, the complexity of social interactions makes this a challenging enterprise. Previous works on cascade models assume that the emergence of this collective phenomenon is related to the activity observed in the local neighborhood of individuals, but do not consider what determines the willingness to spread information in a time-varying process. Here we present a mechanistic model that accounts for the temporal evolution of the individual state in a simplified setup. We model the activity of the individuals as a complex network of interacting integrate-and-fire oscillators. The model reproduces the statistical characteristics of the cascades in real systems, and provides a framework to study time-evolution of cascades in a state-dependent activity scenario.

  5. Impedance Interaction Modeling and Analysis for Bidirectional Cascaded Converters

    DEFF Research Database (Denmark)

    Tian, Yanjun; Deng, Fujin; Chen, Zhe;

    2015-01-01

    more uncertainty to the system stability. An investigation is performed here for showing that the forward and reverse interactions are prominently different in terms of dynamics and stability even though the cascaded converter control remains unchanged. An important guideline has been drawn...

  6. Optimization of cascade-resilient electrical infrastructures and its validation by power flow modeling.

    Science.gov (United States)

    Fang, Yiping; Pedroni, Nicola; Zio, Enrico

    2015-04-01

    Large-scale outages on real-world critical infrastructures, although infrequent, are increasingly disastrous to our society. In this article, we are primarily concerned with power transmission networks and we consider the problem of allocation of generation to distributors by rewiring links under the objectives of maximizing network resilience to cascading failure and minimizing investment costs. The combinatorial multiobjective optimization is carried out by a nondominated sorting binary differential evolution (NSBDE) algorithm. For each generators-distributors connection pattern considered in the NSBDE search, a computationally cheap, topological model of failure cascading in a complex network (named the Motter-Lai [ML] model) is used to simulate and quantify network resilience to cascading failures initiated by targeted attacks. The results on the 400 kV French power transmission network case study show that the proposed method allows us to identify optimal patterns of generators-distributors connection that improve cascading resilience at an acceptable cost. To verify the realistic character of the results obtained by the NSBDE with the embedded ML topological model, a more realistic but also more computationally expensive model of cascading failures is adopted, based on optimal power flow (namely, the ORNL-Pserc-Alaska) model). The consistent results between the two models provide impetus for the use of topological, complex network theory models for analysis and optimization of large infrastructures against cascading failure with the advantages of simplicity, scalability, and low computational cost.

  7. Testing bedrock incision models: Holocene channel evolution, High Cascades, Oregon

    Science.gov (United States)

    Sweeney, K. E.; Roering, J. J.; Fonstad, M. A.

    2013-12-01

    There is abundant field evidence that sediment supply controls the incision of bedrock channels by both protecting the bed from incision and providing tools to incise the bed. Despite several theoretical models for sediment-dependent bedrock abrasion, many investigations of natural channel response to climatic, lithologic, or tectonic forcing rely on the stream power model, which does not consider the role of sediment. Here, we use a well-constrained fluvial channel cut into a Holocene lava flow in the High Cascades, Oregon to compare incision predictions of the stream power model and of the full physics of theoretical models for saltation-abrasion incision by bedload and suspended load. The blocky andesite of Collier lava flow erupted from Collier Cone ~1500 years ago, paving over the existing landscape and erasing fine-scale landscape dissection. Since the eruption, a 6 km stream channel has been incised into the lava flow. The channel is comprised of three alluvial reaches with sediment deposits up to 2 m thick and two bedrock gorges with incision of up to 8 m, with larger magnitude incision in the upstream gorge. Abraded forms such as flutes are present in both gorges. Given the low magnitude and duration of modern snowmelt flow in the channel, it is likely that much of the incision was driven by sediment-laden outburst floods from the terminus of Collier Glacier, which is situated just upstream of the lava flow and has produced two outburst floods in the past 100 years. This site is well suited for comparing incision models because of the relatively uniform lithology of the lava flow and our ability to constrain the timing and depth of incision using the undissected lava surface above the channel as an initial condition. Using a simple finite difference scheme with airborne-Lidar-derived pre-incision topography as an initial condition, we predict incision in the two gorges through time with both stream power and sediment-dependent models. Field observations

  8. Up and down cascade in a dynamo model: spontaneous symmetry breaking.

    Science.gov (United States)

    Blanter, E M; Narteau, C; Shnirman, M G; Le Mouël, J L

    1999-05-01

    A multiscale turbulent model of dynamo is proposed. A secondary magnetic field is generated from a primary field by a flow made of turbulent helical vortices (cyclones) of different ranges, and amplified by an up and down cascade mechanism. The model displays symmetry breakings of different ranges although the system construction is completely symmetric. Large-scale symmetry breakings for symmetric conditions of the system evolution are investigated for all kinds of cascades: pure direct cascade, pure inverse cascade, and up and down cascade. It is shown that long lived symmetry breakings of high scales can be obtained only in the case of the up and down cascade. The symmetry breakings find expression in intervals of constant polarity of the secondary field (called chrons of the geomagnetic field). Long intervals of constant polarity with quick reversals are obtained in the model; conditions for such a behavior are investigated. Strong variations of the generated magnetic field during intervals of constant polarity are also observed in the model. Possible applications of the model to geodynamo modeling and various directions of future investigation are briefly discussed.

  9. DISOPE distributed model predictive control of cascade systems with network communication

    Institute of Scientific and Technical Information of China (English)

    Yan ZHANG; Shaoyuan LI

    2005-01-01

    A novel distributed model predictive control scheme based on dynamic integrated system optimization and parameter estimation (DISOPE) was proposed for nonlinear cascade systems under network environment.Under the distributed control structure,online optimization of the cascade system was composed of several cascaded agents that can cooperate and exchange information via network communication.By iterating on modified distributed linear optimal control problems on the basis of estimating parameters at every iteration the correct optimal control action of the nonlinear model predictive control problem of the cascade system could be obtained,assuming that the algorithm was convergent.This approach avoids solving the complex nonlinear optimization problem and significantly reduces the computational burden.The simulation results of the fossil fuel power unit are illustrated to verify the effectiveness and practicability of the proposed algorithm.

  10. SIMULATION MODELING OF AN ENHANCED LOW-EMISSION SWIRL-CASCADE BURNER

    Energy Technology Data Exchange (ETDEWEB)

    Ala Qubbaj

    2004-04-01

    Based on the physical and computational models outlined in the previous technical progress reports, Natural gas jet diffusion flames in baseline, cascade, swirl, and swirlcascade burners were numerically modeled. The thermal, composition, and flow (velocity) fields were simulated. The temperature, CO{sub 2} and O{sub 2} concentrations, as well as the axial and radial velocity profiles were computed and analyzed. The numerical results showed that swirl and cascade burners have a more efficient fuel/air mixing, a shorter flame, and a lower NOx emission levels, compared to the baseline case. The results also revealed that the optimal configurations of the cascaded and swirling flames have not produced an improved performance when combined together in a ''swirl-cascade burner''.

  11. Extending the Compensatory Model of Second Language Reading

    Science.gov (United States)

    McNeil, Levi

    2012-01-01

    Bernhardt (2005) proposed a compensatory model of second language reading. This model predicted that 50% of second language (L2) reading scores are attributed to second language knowledge and first-language (L1) reading ability. In this model, these two factors compensate for deficiencies in each other. Although this model explains a significant…

  12. Testing an Idealized Dynamic Cascade Model of the Development of Serious Violence in Adolescence

    OpenAIRE

    Dodge, Kenneth A.; Greenberg, Mark T.; Malone, Patrick S.

    2008-01-01

    A dynamic cascade model of development of serious adolescent violence was proposed and tested through prospective inquiry with 754 children (50% male; 43% African American) from 27 schools at 4 geographic sites followed annually from kindergarten through grade 11 (ages 5 through 18). Self, parent, teacher, peer, observer, and administrative reports provided data. Partial least squares (PLS) analyses revealed a cascade of prediction and mediation: An early social context of disadvantage predic...

  13. Talking about Reading as Thinking: Modeling the Hidden Complexities of Online Reading Comprehension

    Science.gov (United States)

    Coiro, Julie

    2011-01-01

    This article highlights four cognitive processes key to online reading comprehension and how one might begin to transform existing think-aloud strategy models to encompass the challenges of reading for information on the Internet. Informed by principles of cognitive apprenticeship and an emerging taxonomy of online reading comprehension…

  14. The Minimalist Reading Model: Rethinking Reading Lists in Arts and Education Subjects

    Science.gov (United States)

    Piscioneri, Matthew; Hlavac, Jim

    2013-01-01

    Despite reading being recognized as a core academic skill, surprisingly little research has been undertaken into university lecture reading requirements. This article reports on the trial and evaluation of a minimalist reading model developed for students in arts and education subjects. Comprising annotated extracts from full texts…

  15. An LCOR model for suppressing cascading failure in weighted complex networks

    Institute of Scientific and Technical Information of China (English)

    Chen Shi-Ming; Pang Shao-Peng; Zou Xiao-Qun

    2013-01-01

    Based on the relationship between capacity and load,cascading failure on weighted complex networks is investigated,and a load-capacity optimal relationship (LCOR) model is proposed in this paper.Compared with three other kinds of loadcapacity linear or non-linear relationship models in model networks as well as a number of real-world weighted networks including the railway network,the airports network and the metro network,the LCOR model is shown to have the best robustness against cascading failure with less cost.Furthermore,theoretical analysis and computational method of its cost threshold are provided to validate the effectiveness of the LCOR model.The results show that the LCOR model is effective for designing real-world networks with high robustness and less cost against cascading failure.

  16. A Comparative Modelling Study of PWM Control Techniques for Multilevel Cascaded Inverter

    Directory of Open Access Journals (Sweden)

    A. TAHRI

    2005-01-01

    Full Text Available The emergence of multilevel converters has been in increase since the last decade. These new types of converters are suitable for high voltage and high power application due to their ability to synthesize waveforms with better harmonic spectrum. Numerous topologies have been introduced and widely studied for utility and drive applications. Amongst these topologies, the multilevel cascaded inverter was introduced in Static Var compensation and drive systems. This paper investigates several control techniques applied to the Multilevel Cascaded Inverter in order to ensure an efficient voltage utilization and better harmonic spectrum. A modelling and control strategy of a single phase Multilevel Cascaded Inverter is also investigated. Computer simulation results using Matlab program are reported and discussed together with a comparative study of the different control techniques of multilevel cascaded inverter.Moreover, experimental results are carried out on a scaled down prototype to prove the effectiveness of the proposed analysis.

  17. Collective influence maximization in threshold models of information cascading with first-order transitions

    CERN Document Server

    Pei, Sen; Shaman, Jeffrey; Morone, Flaviano; Makse, Hernán A

    2016-01-01

    In spreading dynamics in social networks, there exists an optimal set of influencers whose activation can induce a global-scale cascade of information. To find the optimal, or minimal, set of spreaders, a method based on collective influence theory has been proposed for spreading dynamics with a continuous phase transition that can be mapped to optimal percolation. However, when it comes to diffusion processes exhibiting a first-order, or discontinuous transition, identifying the set of optimal spreaders with a linear algorithm for large-scale networks still remains a challenging task. Here we address this issue by exploring the collective influence in general threshold models of opinion cascading. Our analysis reveals that the importance of spreaders is fixed by the subcritical paths along which cascades propagate: the number of subcritical paths attached to each spreader determines its contribution to global cascades. The concept of subcritical path allows us to introduce a linearly scalable algorithm for m...

  18. A NEW CASCADING FAILURE MODEL WITH DELAY TIME IN CONGESTED COMPLEX NETWORKS

    Institute of Scientific and Technical Information of China (English)

    Jian WANG; Yanheng LIU; Yu JIAO

    2009-01-01

    Cascading failures often occur in congested complex networks. Cascading failures can be expressed as a three-phase process: generation, diffusion, and dissipation of congestion. Different from the betweenness centrality, a congestion function is proposed to represent the extent of congestion on a given node. Inspired by the restart process of a node, we introduce the concept of "delay time," during which the overloaded node cannot receive or forward any traffic, so an intergradation between permanent removal and nonremoval is built and the flexibility of the presented model is demonstrated. Considering the connectivity of a network before and after cascading failures is not cracked because the overloaded node are not removed from network permanently in our model, a new evaluation function of network efficiency is also proposed to measure the damage caused by cascading failures. Finally, we investigate the effects of network structure and size, delay time, processing ability, and traffic generation speed on congestion propagation. Cascading processes composed of three phases and some factors affecting cascade propagation are uncovered as well.

  19. Modelling of the Blood Coagulation Cascade in an In Vitro Flow System

    DEFF Research Database (Denmark)

    Andersen, Nina Marianne; Sørensen, Mads Peter; Efendiev, Messoud A.;

    2010-01-01

    We derive a mathematical model of a part of the blood coagulation cascade set up in a perfusion experiment. Our purpose is to simulate the influence of blood flow and diffusion on the blood coagulation pathway. The resulting model consists of a system of partial differential equations taking into...... and flow equations, which guarantee non negative concentrations at all times. The criteria is applied to the model of the blood coagulation cascade.......We derive a mathematical model of a part of the blood coagulation cascade set up in a perfusion experiment. Our purpose is to simulate the influence of blood flow and diffusion on the blood coagulation pathway. The resulting model consists of a system of partial differential equations taking...

  20. SIMULATION MODELING OF AN ENHANCED LOW-EMISSION SWIRL-CASCADE BURNER

    Energy Technology Data Exchange (ETDEWEB)

    Ala Qubbaj

    2003-04-01

    The research team was formed. The advanced CFDRC-CHEMKIN software package was installed on a SUN-SPARC dual processor workstation. The literature pertinent to the project was collected. The physical model was set and all parameters and variables were identified. Based on the physical model, the geometric modeling and grid generation processes were performed using the CFD-GEOM (Interactive Geometric Modeling and Grid Generation software). A total number of 11160 cells (248 x 45) were generated to numerically model the baseline, cascaded, swirling, and swirling-cascaded flames. With the cascade being added to the jet, the geometric complexity of the problem increased; which required multi-domain structured grid systems to be connected and matched on the boundaries.

  1. Empirical analysis of cascade deformable models for multi-view face detection

    NARCIS (Netherlands)

    Orozco, J.; Martinez, B.; Pantic, M.

    2013-01-01

    In this paper, we present a face detector based on Cascade Deformable Part Models (CDPM) [1]. Our model is learnt from partially labelled images using Latent Support Vector Machines (LSVM). Recently Zhu et al. [2] proposed a Tree StructureModel for multi-view face detection trained with facial landm

  2. Power-law behavior in a cascade process with stopping events: a solvable model.

    Science.gov (United States)

    Yamamoto, Ken; Yamazaki, Yoshihiro

    2012-01-01

    The present paper proposes a stochastic model to be solved analytically, and a power-law-like distribution is derived. This model is formulated based on a cascade fracture with the additional effect that each fragment at each stage of a cascade ceases fracture with a certain probability. When the probability is constant, the exponent of the power-law cumulative distribution lies between -1 and 0, depending not only on the probability but the distribution of fracture points. Whereas, when the probability depends on the size of a fragment, the exponent is less than -1, irrespective of the distribution of fracture points. The applicability of our model is also discussed.

  3. An evolutionary cascade model for sauropod dinosaur gigantism--overview, update and tests.

    Science.gov (United States)

    Sander, P Martin

    2013-01-01

    Sauropod dinosaurs are a group of herbivorous dinosaurs which exceeded all other terrestrial vertebrates in mean and maximal body size. Sauropod dinosaurs were also the most successful and long-lived herbivorous tetrapod clade, but no abiological factors such as global environmental parameters conducive to their gigantism can be identified. These facts justify major efforts by evolutionary biologists and paleontologists to understand sauropods as living animals and to explain their evolutionary success and uniquely gigantic body size. Contributions to this research program have come from many fields and can be synthesized into a biological evolutionary cascade model of sauropod dinosaur gigantism (sauropod gigantism ECM). This review focuses on the sauropod gigantism ECM, providing an updated version based on the contributions to the PLoS ONE sauropod gigantism collection and on other very recent published evidence. The model consist of five separate evolutionary cascades ("Reproduction", "Feeding", "Head and neck", "Avian-style lung", and "Metabolism"). Each cascade starts with observed or inferred basal traits that either may be plesiomorphic or derived at the level of Sauropoda. Each trait confers hypothetical selective advantages which permit the evolution of the next trait. Feedback loops in the ECM consist of selective advantages originating from traits higher in the cascades but affecting lower traits. All cascades end in the trait "Very high body mass". Each cascade is linked to at least one other cascade. Important plesiomorphic traits of sauropod dinosaurs that entered the model were ovipary as well as no mastication of food. Important evolutionary innovations (derived traits) were an avian-style respiratory system and an elevated basal metabolic rate. Comparison with other tetrapod lineages identifies factors limiting body size.

  4. An evolutionary cascade model for sauropod dinosaur gigantism--overview, update and tests.

    Directory of Open Access Journals (Sweden)

    P Martin Sander

    Full Text Available Sauropod dinosaurs are a group of herbivorous dinosaurs which exceeded all other terrestrial vertebrates in mean and maximal body size. Sauropod dinosaurs were also the most successful and long-lived herbivorous tetrapod clade, but no abiological factors such as global environmental parameters conducive to their gigantism can be identified. These facts justify major efforts by evolutionary biologists and paleontologists to understand sauropods as living animals and to explain their evolutionary success and uniquely gigantic body size. Contributions to this research program have come from many fields and can be synthesized into a biological evolutionary cascade model of sauropod dinosaur gigantism (sauropod gigantism ECM. This review focuses on the sauropod gigantism ECM, providing an updated version based on the contributions to the PLoS ONE sauropod gigantism collection and on other very recent published evidence. The model consist of five separate evolutionary cascades ("Reproduction", "Feeding", "Head and neck", "Avian-style lung", and "Metabolism". Each cascade starts with observed or inferred basal traits that either may be plesiomorphic or derived at the level of Sauropoda. Each trait confers hypothetical selective advantages which permit the evolution of the next trait. Feedback loops in the ECM consist of selective advantages originating from traits higher in the cascades but affecting lower traits. All cascades end in the trait "Very high body mass". Each cascade is linked to at least one other cascade. Important plesiomorphic traits of sauropod dinosaurs that entered the model were ovipary as well as no mastication of food. Important evolutionary innovations (derived traits were an avian-style respiratory system and an elevated basal metabolic rate. Comparison with other tetrapod lineages identifies factors limiting body size.

  5. Analysis of car-following model with cascade compensation strategy

    Science.gov (United States)

    Zhu, Wen-Xing; Zhang, Li-Dong

    2016-05-01

    Cascade compensation mechanism was designed to improve the dynamical performance of traffic flow system. Two compensation methods were used to study unit step response in time domain and frequency characteristics with different parameters. The overshoot and phase margins are proportional to the compensation parameter in an underdamped condition. Through the comparison we choose the phase-lead compensation method as the main strategy in suppressing the traffic jam. The simulations were conducted under two boundary conditions to verify the validity of the compensator. The conclusion can be drawn that the stability of the system is strengthened with increased phase-lead compensation parameter. Moreover, the numerical simulation results are in good agreement with analytical results.

  6. Empirical analysis of cascade deformable models for multi-view face detection

    NARCIS (Netherlands)

    Orozco, Javier; Martinez, Brais; Pantic, Maja

    2015-01-01

    We present a multi-view face detector based on Cascade Deformable Part Models (CDPM). Over the last decade, there have been several attempts to extend the well-established Viola&Jones face detector algorithm to solve the problem of multi-view face detection. Recently a tree structure model for multi

  7. ARRA: Reconfiguring Power Systems to Minimize Cascading Failures - Models and Algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Dobson, Ian [Iowa State University; Hiskens, Ian [Unversity of Michigan; Linderoth, Jeffrey [University of Wisconsin-Madison; Wright, Stephen [University of Wisconsin-Madison

    2013-12-16

    Building on models of electrical power systems, and on powerful mathematical techniques including optimization, model predictive control, and simluation, this project investigated important issues related to the stable operation of power grids. A topic of particular focus was cascading failures of the power grid: simulation, quantification, mitigation, and control. We also analyzed the vulnerability of networks to component failures, and the design of networks that are responsive to and robust to such failures. Numerous other related topics were investigated, including energy hubs and cascading stall of induction machines

  8. On Reading-Based Writing Instruction Model

    Institute of Scientific and Technical Information of China (English)

    李大艳; 王建安

    2012-01-01

    English writing is a complex integrative process of comprehensive skills. A host of students are still unable to write a coherent English paragraph after having learned English for many years at school. To help college students improve their writing competence is a great challenge facing the English teaching in China. Researches on writing teaching method abroad have experienced prosperity. In China, however, researches in this field are far behind. There is great need to search for more efficient writing instruction model so that it can serve well in Chinese context. Enlightened by Krashen's input hypothesis and Swain's output hypothesis, the writer put forward Reading-Based Writing Instruction Model. This paper aims to discuss the effectiveness of this model from the different perspectives.

  9. Joint state and parameter estimation for a class of cascade systems: Application to a hemodynamic model

    KAUST Repository

    Zayane, Chadia

    2014-06-01

    In this paper, we address a special case of state and parameter estimation, where the system can be put on a cascade form allowing to estimate the state components and the set of unknown parameters separately. Inspired by the nonlinear Balloon hemodynamic model for functional Magnetic Resonance Imaging problem, we propose a hierarchical approach. The system is divided into two subsystems in cascade. The state and input are first estimated from a noisy measured signal using an adaptive observer. The obtained input is then used to estimate the parameters of a linear system using the modulating functions method. Some numerical results are presented to illustrate the efficiency of the proposed method.

  10. Simulation Modeling of an Enhanced Low-Emission Swirl-Cascade Burner

    Energy Technology Data Exchange (ETDEWEB)

    Ala Qubbaj

    2004-09-01

    ''Cascade-burners'' is a passive technique to control the stoichiometry of the flame through changing the flow dynamics and rates of mixing in the combustion zone with a set of venturis surrounding the flame. Cascade-burners have shown advantages over other techniques; its reliability, flexibility, safety, and cost makes it more attractive and desirable. On the other hand, the application of ''Swirl-burners'' has shown superiority in producing a stable flame under a variety of operating conditions and fuel types. The basic idea is to impart swirl to the air or fuel stream, or both. This not only helps to stabilize the flame but also enhances mixing in the combustion zone. As a result, nonpremixed (diffusion) swirl burners have been increasingly used in industrial combustion systems such as gas turbines, boilers, and furnaces, due to their advantages of safety and stability. Despite the advantages of cascade and swirl burners, both are passive control techniques, which resulted in a moderate pollutant emissions reduction compared to SCR, SNCR and FGR (active) methods. The present investigation will study the prospects of combining both techniques in what to be named as ''an enhanced swirl-cascade burner''. Natural gas jet diffusion flames in baseline, cascade, swirl, and swirl-cascade burners were numerically modeled using CFDRC package. The thermal, composition, and flow (velocity) fields were simulated. The numerical results showed that swirl and cascade burners have a more efficient fuel/air mixing, a shorter flame, and a lower NOx emission levels, compared to the baseline case. The results also revealed that the optimal configurations of the cascaded and swirling flames have not produced an improved performance when combined together in a ''swirl-cascade burner''. The non-linearity and complexity of the system accounts for such a result, and therefore, all possible combinations, i

  11. Sediment Deposition Risk Analysis and PLSR Model Research for Cascade Reservoirs Upstream of the Yellow River

    Directory of Open Access Journals (Sweden)

    Jie Yang

    2015-01-01

    Full Text Available It is difficult to effectively identify and eliminate the multiple correlation influence among the independent factors by least-squares regression. Focusing on this insufficiency, the sediment deposition risk of cascade reservoirs and fitting model of sediment flux into the reservoir are studied. The partial least-squares regression (PLSR method is adopted for modeling analysis; the model fitting is organically combined with the non-model-style data content analysis, so as to realize the regression model, data structure simplification, and multiple correlations analysis among factors; meanwhile the accuracy of the model is ensured through cross validity check. The modeling analysis of sediment flux into the cascade reservoirs of Long-Liu section upstream of the Yellow River indicates that partial least-squares regression can effectively overcome the multiple correlation influence among factors, and the isolated factor variables have better ability to explain the physical cause of measured results.

  12. Reading Time as Evidence for Mental Models in Understanding Physics

    Science.gov (United States)

    Brookes, David T.; Mestre, José; Stine-Morrow, Elizabeth A. L.

    2007-11-01

    We present results of a reading study that show the usefulness of probing physics students' cognitive processing by measuring reading time. According to contemporary discourse theory, when people read a text, a network of associated inferences is activated to create a mental model. If the reader encounters an idea in the text that conflicts with existing knowledge, the construction of a coherent mental model is disrupted and reading times are prolonged, as measured using a simple self-paced reading paradigm. We used this effect to study how "non-Newtonian" and "Newtonian" students create mental models of conceptual systems in physics as they read texts related to the ideas of Newton's third law, energy, and momentum. We found significant effects of prior knowledge state on patterns of reading time, suggesting that students attempt to actively integrate physics texts with their existing knowledge.

  13. Using the Cascade Model to Improve Antenatal Screening for the Hemoglobin Disorders

    Science.gov (United States)

    Gould, Dinah; Papadopoulos, Irena; Kelly, Daniel

    2012-01-01

    Introduction: The inherited hemoglobin disorders constitute a major public health problem. Facilitators (experienced hemoglobin counselors) were trained to deliver knowledge and skills to "frontline" practitioners to enable them to support parents during antenatal screening via a cascade (train-the-trainer) model. Objectives of…

  14. Temperament Pathways to Childhood Disruptive Behavior and Adolescent Substance Abuse: Testing a Cascade Model

    Science.gov (United States)

    Martel, Michelle M.; Pierce, Laura; Nigg, Joel T.; Jester, Jennifer M.; Adams, Kenneth; Puttler, Leon I.; Buu, Anne; Fitzgerald, Hiram; Zucker, Robert A.

    2009-01-01

    Temperament traits may increase risk for developmental psychopathology like Attention-Deficit/Hyperactivity Disorder (ADHD) and disruptive behaviors during childhood, as well as predisposing to substance abuse during adolescence. In the current study, a cascade model of trait pathways to adolescent substance abuse was examined. Component…

  15. The Transfer of Content Knowledge in a Cascade Model of Professional Development

    Science.gov (United States)

    Turner, Fay; Brownhill, Simon; Wilson, Elaine

    2017-01-01

    A cascade model of professional development presents a particular risk that "knowledge" promoted in a programme will be diluted or distorted as it passes from originators of the programme to local trainers and then to the target teachers. Careful monitoring of trainers' and teachers' knowledge as it is transferred through the system is…

  16. Using the Cascade Model to Improve Antenatal Screening for the Hemoglobin Disorders

    Science.gov (United States)

    Gould, Dinah; Papadopoulos, Irena; Kelly, Daniel

    2012-01-01

    Introduction: The inherited hemoglobin disorders constitute a major public health problem. Facilitators (experienced hemoglobin counselors) were trained to deliver knowledge and skills to "frontline" practitioners to enable them to support parents during antenatal screening via a cascade (train-the-trainer) model. Objectives of evaluation were to…

  17. Temperament Pathways to Childhood Disruptive Behavior and Adolescent Substance Abuse: Testing a Cascade Model

    Science.gov (United States)

    Martel, Michelle M.; Pierce, Laura; Nigg, Joel T.; Jester, Jennifer M.; Adams, Kenneth; Puttler, Leon I.; Buu, Anne; Fitzgerald, Hiram; Zucker, Robert A.

    2009-01-01

    Temperament traits may increase risk for developmental psychopathology like Attention-Deficit/Hyperactivity Disorder (ADHD) and disruptive behaviors during childhood, as well as predisposing to substance abuse during adolescence. In the current study, a cascade model of trait pathways to adolescent substance abuse was examined. Component…

  18. Testing an Idealized Dynamic Cascade Model of the Development of Serious Violence in Adolescence

    Science.gov (United States)

    Dodge, Kenneth A.; Greenberg, Mark T.; Malone, Patrick S.

    2008-01-01

    A dynamic cascade model of development of serious adolescent violence was proposed and tested through prospective inquiry with 754 children (50% male; 43% African American) from 27 schools at 4 geographic sites followed annually from kindergarten through Grade 11 (ages 5-18). Self, parent, teacher, peer, observer, and administrative reports…

  19. Molecular dynamics and binary collision modeling of the primary damage state of collision cascades

    DEFF Research Database (Denmark)

    Heinisch, H.L.; Singh, B.N.

    1992-01-01

    Quantitative information on defect production in cascades in copper obtained from recent molecular dynamics simulations is compared to defect production information determined earlier with a model based on the binary collision approximation (BCA). The total numbers of residual defects, the fracti...

  20. Modeling cascading failures with the crisis of trust in social networks

    Science.gov (United States)

    Yi, Chengqi; Bao, Yuanyuan; Jiang, Jingchi; Xue, Yibo

    2015-10-01

    In social networks, some friends often post or disseminate malicious information, such as advertising messages, informal overseas purchasing messages, illegal messages, or rumors. Too much malicious information may cause a feeling of intense annoyance. When the feeling exceeds a certain threshold, it will lead social network users to distrust these friends, which we call the crisis of trust. The crisis of trust in social networks has already become a universal concern and an urgent unsolved problem. As a result of the crisis of trust, users will cut off their relationships with some of their untrustworthy friends. Once a few of these relationships are made unavailable, it is likely that other friends will decline trust, and a large portion of the social network will be influenced. The phenomenon in which the unavailability of a few relationships will trigger the failure of successive relationships is known as cascading failure dynamics. To our best knowledge, no one has formally proposed cascading failures dynamics with the crisis of trust in social networks. In this paper, we address this potential issue, quantify the trust between two users based on user similarity, and model the minimum tolerance with a nonlinear equation. Furthermore, we construct the processes of cascading failures dynamics by considering the unique features of social networks. Based on real social network datasets (Sina Weibo, Facebook and Twitter), we adopt two attack strategies (the highest trust attack (HT) and the lowest trust attack (LT)) to evaluate the proposed dynamics and to further analyze the changes of the topology, connectivity, cascading time and cascade effect under the above attacks. We numerically find that the sparse and inhomogeneous network structure in our cascading model can better improve the robustness of social networks than the dense and homogeneous structure. However, the network structure that seems like ripples is more vulnerable than the other two network

  1. An Exactly Soluble Hierarchical Clustering Model Inverse Cascades, Self-Similarity, and Scaling

    CERN Document Server

    Gabrielov, A; Turcotte, D L

    1999-01-01

    We show how clustering as a general hierarchical dynamical process proceeds via a sequence of inverse cascades to produce self-similar scaling, as an intermediate asymptotic, which then truncates at the largest spatial scales. We show how this model can provide a general explanation for the behavior of several models that has been described as ``self-organized critical,'' including forest-fire, sandpile, and slider-block models.

  2. Mathematical Model of Extrinsic Blood Coagulation Cascade Dynamic System

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The blood coagulation system is very important to life. This paper presents a mathematical blood coagulation model for the extrinsic pathway. This model simulates clotting factor VIII, which plays an important role in the coagulation mechanism. The mathematical model is used to study the equilibrium stability, orbit structure, attractors and global stability behavior, with conclusions in accordance with the physiological phenomena. Moreover, the results provide information about blood related illnesses, which can be used for further study of the coagulation mechanism.

  3. A Lattice Model of the Development of Reading Comprehension.

    Science.gov (United States)

    Connor, Carol McDonald

    2016-12-01

    In this article, I present a developmental model of how children learn to comprehend what they read, which builds on current models of reading comprehension and integrates findings from instructional research and evidence-based models of development in early and middle childhood. The lattice model holds that children's developing reading comprehension is a function of the interacting, reciprocal, and bootstrapping effects of developing text-specific, linguistic, and social-cognitive processes, which interact with instruction as child-characteristic-by-instruction (CXI) interaction effects. The processes develop over time and in the context of classroom, home, peer, community, and other influences to affect children's development of proficient reading comprehension. I first describe models of reading comprehension. I then review the basic processes in the model, the role of instruction, and CXI interactions in the context of the lattice model. I then discuss implications for instruction and research.

  4. Extension of the Li\\`ege Intranuclear-Cascade model to reactions induced by light nuclei

    CERN Document Server

    Mancusi, Davide; Cugnon, Joseph; David, Jean-Christophe; Kaitaniemi, Pekka; Leray, Sylvie

    2014-01-01

    The purpose of this paper is twofold. First, we present the extension of the Li\\`ege Intranuclear Cascade model to reactions induced by light ions. Second, we describe the C++ version of the code, which it is physics-wise equivalent to the legacy version, is available in Geant4 and will serve as the basis for all future development of the model. We describe the ideas upon which we built our treatment of nucleus-nucleus reactions and we compare the model predictions against a vast set of heterogeneous experimental data. In spite of the discussed limitations of the intranuclear-cascade scheme, we find that our model yields valid predictions for a number of observables and positions itself as one of the most attractive alternatives available to Geant4 users for the simulation of light-ion-induced reactions.

  5. Effects of temporal correlations on cascades: Threshold models on temporal networks

    CERN Document Server

    Backlund, Ville-Pekka; Pan, Raj Kumar

    2014-01-01

    A person's decision to adopt an idea or product is often driven by the decisions of peers, mediated through a network of social ties. A common way of modeling adoption dynamics is to use threshold models, where a node may become an adopter given a high enough rate of contacts with adopted neighbors. We study the dynamics of threshold models that take both the network topology and the timings of contacts into account, using empirical contact sequences as substrates. The models are designed such that adoption is driven by the number of contacts with different adopted neighbors within a chosen time. We find that while some networks support cascades leading to network-level adoption, some do not: the propagation of adoption depends on several factors from the frequency of contacts to burstiness and timing correlations of contact sequences. More specifically, burstiness is seen to suppress cascades sizes when compared to randomised contact timings, while timing correlations between contacts on adjacent links facil...

  6. Experimental calibration of the mathematical model of Air Torque Position dampers with non-cascading blades

    Directory of Open Access Journals (Sweden)

    Bikić Siniša M.

    2016-01-01

    Full Text Available This paper is focused on the mathematical model of the Air Torque Position dampers. The mathematical model establishes a link between the velocity of air in front of the damper, position of the damper blade and the moment acting on the blade caused by the air flow. This research aims to experimentally verify the mathematical model for the damper type with non-cascading blades. Four different types of dampers with non-cascading blades were considered: single blade dampers, dampers with two cross-blades, dampers with two parallel blades and dampers with two blades of which one is a fixed blade in the horizontal position. The case of a damper with a straight pipeline positioned in front of and behind the damper was taken in consideration. Calibration and verification of the mathematical model was conducted experimentally. The experiment was conducted on the laboratory facility for testing dampers used for regulation of the air flow rate in heating, ventilation and air conditioning systems. The design and setup of the laboratory facility, as well as construction, adjustment and calibration of the laboratory damper are presented in this paper. The mathematical model was calibrated by using one set of data, while the verification of the mathematical model was conducted by using the second set of data. The mathematical model was successfully validated and it can be used for accurate measurement of the air velocity on dampers with non-cascading blades under different operating conditions. [Projekat Ministarstva nauke Republike Srbije, br. TR31058

  7. PACIAE 2.0: An Updated Parton and Hadron Cascade Model (Program) for Relativistic Nuclear Collisions

    Institute of Scientific and Technical Information of China (English)

    SA; Ben-hao; ZHOU; Dai-mei; YAN; Yu-liang; LI; Xiao-mei; FENG; Sheng-qing; DONG; Bao-guo; CAI; Xu

    2012-01-01

    <正>We have updated the parton and hadron cascade model PACIAE for the relativistic nuclear collisions, from based on JETSET 6.4 and PYTHIA 5.7, and referred to as PACIAE 2.0. The main physics concerning the stages of the parton initiation, parton rescattering, hadronization, and hadron rescattering were discussed. The structures of the programs were briefly explained. In addition, some calculated examples were compared with the experimental data. It turns out that this model (program) works well.

  8. Cascade recursion models of computing the temperatures of underground layers

    Institute of Scientific and Technical Information of China (English)

    HAN; Liqun; BI; Siwen; SONG; Shixin

    2006-01-01

    An RBF neural network was used to construct computational models of the underground temperatures of different layers, using ground-surface parameters and the temperatures of various underground layers. Because series recursion models also enable researchers to use above-ground surface parameters to compute the temperatures of different underground layers, this method provides a new way of using thermal infrared remote sensing to monitor the suture zones of large areas of blocks and to research thermal anomalies in geologic structures.

  9. Developing a structural model of reading: the role of hearing status in reading development over time.

    Science.gov (United States)

    Coppens, Karien M; Tellings, Agnes; Schreuder, Robert; Verhoeven, Ludo

    2013-10-01

    The purpose of the present study was to develop a structural model of reading based on the Lexical Quality Hypothesis (Perfetti & Hart, 2002). Data from a 4-year longitudinal study of Dutch primary school children with and without hearing loss were used to conduct an exploratory analysis of how lexical components (i.e., decoding skills, lexical decision, and lexical use) relate to one another and to reading comprehension. Our structural model supports a positive role of the quality of the mental lexicon for reading comprehension. Furthermore, it was possible to apply the same conceptual model of reading development to both groups of children when incorporating hearing status as a grouping variable. However, a multigroup comparison model showed that the predictive values of the relations between the different tasks differed for the two groups.

  10. Distributed energy balance modeling of South Cascade Glacier, Washington and assessment of model uncertainty

    Science.gov (United States)

    Anslow, Faron S.; Hostetler, S.; Bidlake, W.R.; Clark, P.U.

    2008-01-01

    We have developed a physically based, distributed surface energy balance model to simulate glacier mass balance under meteorological and climatological forcing. Here we apply the model to estimate summer ablation on South Cascade Glacier, Washington, for the 2004 and 2005 mass balance seasons. To arrive at optimal mass balance simulations, we investigate and quantify model uncertainty associated with selecting from a range of physical parameter values that are not commonly measured in glaciological mass balance field studies. We optimize the performance of the model by varying values for atmospheric transmissivity, the albedo of surrounding topography, precipitation-elevation lapse rate, surface roughness for turbulent exchange of momentum, and snow albedo aging coefficient. Of these the snow aging parameter and precipitation lapse rates have the greatest influence on the modeled ablation. We examined model sensitivity to varying parameters by performing an additional 103 realizations with parameters randomly chosen over a ??5% range centered about the optimum values. The best fit suite of model parameters yielded a net balance of -1.69??0.38 m water equivalent (WE) for the 2004 water year and -2.10??0.30 m WE up to 11 September 2005. The 2004 result is within 3% of the measured value. These simulations account for 91% and 93% of the variance in measured ablation for the respective years. Copyright 2008 by the American Geophysical Union.

  11. Importance of coherence in models of mid-infrared quantum cascade laser gain spectra

    Science.gov (United States)

    Cui, Yuzhang I.; Harter, Michael P.; Dikmelik, Yamac; Hoffman, Anthony J.

    2017-09-01

    We present a three-level model based on a density matrix to examine the influence of coherence and dephasing on the gain spectrum of mid-infrared quantum cascade lasers. The model is used to examine a quantum cascade active region with multiple optical transitions. We show how coherence can explain the origin of additional peaks in the gain spectrum. We also analyze the spectra calculated using the three-level model with a rate equation formalism to demonstrate the importance of considering interface roughness and limitations of the rate equation formalism. Specifically, we present how interface roughness influences the broadening and oscillator strength that are recovered using a rate equation analysis. The results of this work are important when considering the design of active regions with multiple optical transitions and could lead to devices with improved performance.

  12. Hydraulic modeling for lahar hazards at cascades volcanoes

    Science.gov (United States)

    Costa, J.E.

    1997-01-01

    The National Weather Service flood routing model DAMBRK is able to closely replicate field-documented stages of historic and prehistoric lahars from Mt. Rainier, Washington, and Mt. Hood, Oregon. Modeled time-of-travel of flow waves are generally consistent with documented lahar travel-times from other volcanoes around the world. The model adequately replicates a range of lahars and debris flows, including the 230 million km3 Electron lahar from Mt. Rainier, as well as a 10 m3 debris flow generated in a large outdoor experimental flume. The model is used to simulate a hypothetical lahar with a volume of 50 million m3 down the East Fork Hood River from Mt. Hood, Oregon. Although a flow such as this is thought to be possible in the Hood River valley, no field evidence exists on which to base a hazards assessment. DAMBRK seems likely to be usable in many volcanic settings to estimate discharge, velocity, and inundation areas of lahars when input hydrographs and energy-loss coefficients can be reasonably estimated.

  13. Integrated snow and hydrology modeling for climate change impact assessment in Oregon Cascades

    Science.gov (United States)

    Safeeq, M.; Grant, G.; Lewis, S.; Nolin, A. W.; Hempel, L. A.; Cooper, M.; Tague, C.

    2014-12-01

    In the Pacific Northwest (PNW), increasing temperatures are expected to alter the hydrologic regimes of streams by shifting precipitation from snow to rain and forcing earlier snowmelt. How are such changes likely to affect peak flows across the region? Shifts in peak flows have obvious implications for changing flood risk, but are also likely to affect channel morphology, sediment transport, aquatic habitat, and water quality, issues with potentially high economic and environmental cost. Our goal, then, is to rigorously evaluate sensitivity to potential peak flow changes across the PNW. We address this by developing a detailed representation of snowpack and streamflow evolution under varying climate scenarios using a cascade-modeling approach. We have identified paired watersheds located on the east (Metolius River) and west (McKenzie River) sides of the Cascades, representing dry and wet climatic regimes, respectively. The tributaries of these two rivers are comprised of contrasting hydrologic regimes: surface-runoff dominated western cascades and deep-groundwater dominated high-cascades systems. We use a detailed hydro-ecological model (RHESSys) in conjunction with a spatially distributed snowpack evolution model (SnowModel) to characterize the peak flow behavior under present and future climate. We first calibrated and validated the SnowModel using observed temperature, precipitation, snow water equivalent, and manual snow survey data sets. We then employed a multi-objective calibration strategy for RHESSys using the simulated snow accumulation and melt from SnowModel and observed streamflow. The Nash-Sutcliffe Efficiency between observed and simulated streamflow varies between 0.5 in groundwater and 0.71 in surface-runoff dominated systems. The initial results indicate enhanced peak flow under future climate across all basins, but the magnitude of increase varies by the level of snowpack and deep-groundwater contribution in the watershed. Our continuing effort

  14. Does the PMSP Connectionist Model of Single Word Reading Learn to Read in the Same Way as a Child?

    Science.gov (United States)

    Powell, Daisy; Plaut, David; Funnell, Elaine

    2006-01-01

    The Plaut, McClelland, Seidenberg and Patterson (1996) connectionist model of reading was evaluated at two points early in its training against reading data collected from British children on two occasions during their first year of literacy instruction. First, the network's non-word reading was poor relative to word reading when compared with the…

  15. Cascaded Network Body Channel Model for Intrabody Communication.

    Science.gov (United States)

    Wang, Hao; Tang, Xian; Choy, Chiu Sing; Sobelman, Gerald E

    2016-07-01

    Intrabody communication has been of great research interest in recent years. This paper proposes a novel, compact but accurate body transmission channel model based on RC distribution networks and transmission line theory. The comparison between simulation and measurement results indicates that the proposed approach accurately models the body channel characteristics. In addition, the impedance-matching networks at the transmitter output and the receiver input further maximize the power transferred to the receiver, relax the receiver complexity, and increase the transmission performance. Based on the simulation results, the power gain can be increased by up to 16 dB after matching. A binary phase-shift keying modulation scheme is also used to evaluate the bit-error-rate improvement.

  16. Modeling elephant-mediated cascading effects of water point closure.

    Science.gov (United States)

    Hilbers, Jelle P; Van Langevelde, Frank; Prins, Herbert H T; Grant, C C; Peel, Mike J S; Coughenour, Michael B; De Knegt, Henrik J; Slotow, Rob; Smit, Izak P J; Kiker, Greg A; De Boer, Willem F

    2015-03-01

    Wildlife management to reduce the impact of wildlife on their habitat can be done in several ways, among which removing animals (by either culling or translocation) is most often used. There are, however, alternative ways to control wildlife densities, such as opening or closing water points. The effects of these alternatives are poorly studied. In this paper, we focus on manipulating large herbivores through the closure of water points (WPs). Removal of artificial WPs has been suggested in order to change the distribution of African elephants, which occur in high densities in national parks in Southern Africa and are thought to have a destructive effect on the vegetation. Here, we modeled the long-term effects of different scenarios of WP closure on the spatial distribution of elephants, and consequential effects on the vegetation and other herbivores in Kruger National Park, South Africa. Using a dynamic ecosystem model, SAVANNA, scenarios were evaluated that varied in availability of artificial WPs; levels of natural water; and elephant densities. Our modeling results showed that elephants can indirectly negatively affect the distributions of meso-mixed feeders, meso-browsers, and some meso-grazers under wet conditions. The closure of artificial WPs hardly had any effect during these natural wet conditions. Under dry conditions, the spatial distribution of both elephant bulls and cows changed when the availability of artificial water was severely reduced in the model. These changes in spatial distribution triggered changes in the spatial availability of woody biomass over the simulation period of 80 years, and this led to changes in the rest of the herbivore community, resulting in increased densities of all herbivores, except for giraffe and steenbok, in areas close to rivers. The spatial distributions of elephant bulls and cows showed to be less affected by the closure of WPs than most of the other herbivore species. Our study contributes to ecologically

  17. Incorporating RTI in a Hybrid Model of Reading Disability

    OpenAIRE

    2014-01-01

    The present study seeks to evaluate a hybrid model of identification that incorporates response-to-intervention (RTI) as a one of the key symptoms of reading disability. The one-year stability of alternative operational definitions of reading disability was examined in a large scale sample of students who were followed longitudinally from first to second grade. The results confirmed previous findings of limited stability for single-criterion based operational definitions of reading disability...

  18. A Cascade Model for Particle Concentration and Enstrophy in Fully Developed Turbulence with Mass Loading Feedback

    CERN Document Server

    Hogan, Robert C

    2007-01-01

    A cascade model is described based on multiplier distributions determined from 3D direct numerical simulations (DNS) of turbulent particle laden flows, which include two-way coupling between the phases at global mass loadings equal to unity. The governing Eulerian equations are solved using pseudo-spectral methods on up to 512**3 computional grid points. DNS results for particle concentration and enstrophy at Taylor microscale Reynolds numbers in the range 34 - 170 were used to directly determine multiplier distributions (PDFs) on spatial scales 3 times the Kolmogorov length scale. The width of the PDFs, which is a measure of intermittency, decreases with increasing mass loading within the local region where the multipliers are measured. The functional form of this dependence is not sensitive to Reynolds numbers in the range considered. A partition correlation probability is included in the cascade model to account for the observed spatial anticorrelation between particle concentration and enstrophy. Joint pr...

  19. Temperament Pathways to Childhood Disruptive Behavior and Adolescent Substance Abuse: Testing a Cascade Model

    OpenAIRE

    Martel, Michelle M.; Pierce, Laura; Nigg, Joel T.; Jester, Jennifer M.; Adams, Kenneth; Puttler, Leon I.; Buu, Anne; Fitzgerald, Hiram; Zucker, Robert A.

    2009-01-01

    Temperament traits may increase risk for developmental psychopathology like Attention-Deficit/Hyperactivity Disorder (ADHD) and disruptive behaviors during childhood, as well as predisposing to substance abuse during adolescence. In the current study, a cascade model of trait pathways to adolescent substance abuse was examined. Component hypotheses were that (a) maladaptive traits would increase risk for inattention/hyperactivity, (b) inattention/hyperactivity would increase risk for disrupti...

  20. Lumped-equivalent circuit model for multi-stage cascaded magnetoelectric dual-tunable bandpass filter

    Institute of Scientific and Technical Information of China (English)

    张秋实; 朱锋杰; 周浩淼

    2015-01-01

    A lumped-equivalent circuit model of a novel magnetoelectric tunable bandpass filter, which is realized in the form of multi-stage cascading between a plurality of magnetoelectric laminates, is established in this paper for convenient analysis. The multi-stage cascaded filter is degraded to the coupling microstrip filter with only one magnetoelectric laminate and then compared with the existing experiment results. The comparison reveals that the insertion loss curves predicted by the degraded circuit model are in good agreement with the experiment results and the predicted results of the electromagnetic field simulation, thus the validity of the model is verified. The model is then degraded to the two-stage cascaded magneto-electric filter with two magnetoelectric laminates. It is revealed that if the applied external bias magnetic or electric fields on the two magnetoelectric laminates are identical, then the passband of the filter will drift under the changed external field; that is to say, the filter has the characteristics of external magnetic field tunability and electric field tunability. If the applied external bias magnetic or electric fields on two magnetoelectric laminates are different, then the passband will disappear so that the switching characteristic is achieved. When the same magnetic fields are applied to the laminates, the passband bandwidth of the two-stage cascaded magnetoelectric filter with two magnetoelectric laminates becomes nearly doubled in comparison with the passband filter which contains only one magnetoelectric laminate. The bandpass effect is also improved obviously. This research will provide a theoretical basis for the design, preparation, and application of a new high performance magnetoelectric tunable microwave device.

  1. Multi-scale interactions of geological processes during mineralization: cascade dynamics model and multifractal simulation

    Directory of Open Access Journals (Sweden)

    L. Yao

    2011-03-01

    Full Text Available Relations between mineralization and certain geological processes are established mostly by geologist's knowledge of field observations. However, these relations are descriptive and a quantitative model of how certain geological processes strengthen or hinder mineralization is not clear, that is to say, the mechanism of the interactions between mineralization and the geological framework has not been thoroughly studied. The dynamics behind these interactions are key in the understanding of fractal or multifractal formations caused by mineralization, among which singularities arise due to anomalous concentration of metals in narrow space. From a statistical point of view, we think that cascade dynamics play an important role in mineralization and studying them can reveal the nature of the various interactions throughout the process. We have constructed a multiplicative cascade model to simulate these dynamics. The probabilities of mineral deposit occurrences are used to represent direct results of mineralization. Multifractal simulation of probabilities of mineral potential based on our model is exemplified by a case study dealing with hydrothermal gold deposits in southern Nova Scotia, Canada. The extent of the impacts of certain geological processes on gold mineralization is related to the scale of the cascade process, especially to the maximum cascade division number nmax. Our research helps to understand how the singularity occurs during mineralization, which remains unanswered up to now, and the simulation may provide a more accurate distribution of mineral deposit occurrences that can be used to improve the results of the weights of evidence model in mapping mineral potential.

  2. Cascade model for particle concentration and enstrophy in fully developed turbulence with mass-loading feedback.

    Science.gov (United States)

    Hogan, R C; Cuzzi, J N

    2007-05-01

    A cascade model is described based on multiplier distributions determined from three-dimensional (3D) direct numerical simulations (DNS) of turbulent particle laden flows, which include two-way coupling between the phases at global mass loadings equal to unity. The governing Eulerian equations are solved using psuedospectral methods on up to 512(3) computional grid points. DNS results for particle concentration and enstrophy at Taylor microscale Reynolds numbers in the range 34-170 were used to directly determine multiplier distributions on spatial scales three times the Kolmogorov length scale. The multiplier probability distribution functions (PDFs) are well characterized by the beta distribution function. The width of the PDFs, which is a measure of intermittency, decreases with increasing mass loading within the local region where the multipliers are measured. The functional form of this dependence is not sensitive to Reynolds numbers in the range considered. A partition correlation probability is included in the cascade model to account for the observed spatial anticorrelation between particle concentration and enstrophy. Joint probability distribution functions of concentration and enstrophy generated using the cascade model are shown to be in excellent agreement with those derived directly from our 3D simulations. Probabilities predicted by the cascade model are presented at Reynolds numbers well beyond what is achievable by direct simulation. These results clearly indicate that particle mass loading significantly reduces the probabilities of high particle concentration and enstrophy relative to those resulting from unloaded runs. Particle mass density appears to reach a limit at around 100 times the gas density. This approach has promise for significant computational savings in certain applications.

  3. Incorporating RTI in a Hybrid Model of Reading Disability

    Science.gov (United States)

    Spencer, Mercedes; Wagner, Richard K.; Schatschneider, Christopher; Quinn, Jamie M.; Lopez, Danielle; Petscher, Yaacov

    2014-01-01

    The present study seeks to evaluate a hybrid model of identification that incorporates response to instruction and intervention (RTI) as one of the key symptoms of reading disability. The 1-year stability of alternative operational definitions of reading disability was examined in a large-scale sample of students who were followed longitudinally…

  4. SIMULATION MODELING OF AN ENHANCED LOW-EMISSION SWIRL-CASCADE BURNER

    Energy Technology Data Exchange (ETDEWEB)

    Ala Qubbaj

    2003-10-01

    The numerical computations were conducted using the CFD-CHEMKIN computational program. A cell-centered control volume approach was used, in which the discretized equations or the finite difference equations (FDE) were formulated by evaluating and integrating fluxes across the faces of control volumes in order to satisfy the continuity, momentum, energy and mixture fractions conservation equations. The first order upwind scheme and the well-known SIMPLEC algorithm were used. The standard k-{var_epsilon} model was used to close the set of equations. The thermal and composition fields in the baseline, cascade, swirl, and swirl-cascade burners were simulated. The temperature and CO{sub 2} concentration fields were just computed and the observations are reported. The analysis of these results is currently underway.

  5. DEVELOPING A MODEL OF TEACHING READING COMPREHENSION FOR EFL STUDENTS

    Directory of Open Access Journals (Sweden)

    Arifuddin Hamra

    2010-02-01

    Full Text Available This study aimed at designing a model of teaching reading comprehension based on the objectives of teaching reading at the senior high school and the teachers’ understanding of the school curriculum and to describe the implementation of the model. The subject consisted of 24 teachers, 167 students of five SMAs (senior high schools in South Sulawesi, Indonesia. This developmental study had five steps: analysis, design, development, implementation, and evaluation. The result indicates that the model significantly increases the reading comprehension of EFL students (M = -14.43114, t (166 = -16.155, p

  6. [Dual neural circuit model of reading and writing].

    Science.gov (United States)

    Iwata, Makoto

    2011-08-01

    In the hypothetical neural circuit model of reading and writing that was initially proposed by Dejerine and subsequently confirmed by Geschwind, the left angular gyrus was considered as a unique center for processing letters. Japanese investigators, however, have repeatedly pointed out that this angular gyrus model cannot fully explain the disturbances observed in reading and writing Kanji letters in Japanese patients with various types of alexia with or without agraphia. In 1982, I proposed a dual neural circuit model of reading and writing Japanese on the basis of neuropsychological studies on the various types of alexia with or without agraphia without aphasia. This dual neural circuit model proposes that apart from the left angular gyrus which was thought to be a node for phonological processing of letters, the left posterior inferior temporal area, also acts as a node for semantic processing of letters. Further investigations using O15-PET activation on normal subjects revealed that the left middle occipital gyrus (area 19 of Brodmann) and the posterior portion of the left inferior temporal gyrus (area 37 of Brodmann) are the cortical areas responsible for reading Japanese letters; the former serving for phonological reading and the latter for semantic reading. This duality of the neural circuit in processing letters was later applied to explain disturbances in reading English, and was finally accepted as a valid model for other alphabetic letter systems too.

  7. Multiscale equatorial electrojet turbulence: Energy conservation, coupling, and cascades in a baseline 2-D fluid model

    Science.gov (United States)

    Hassan, Ehab; Hatch, D. R.; Morrison, P. J.; Horton, W.

    2016-09-01

    Progress in understanding the coupling between plasma instabilities in the equatorial electrojet based on a unified fluid model is reported. Simulations with parameters set to various ionospheric background conditions revealed properties of the gradient-drift and Farley-Buneman instabilities. Notably, sharper density gradients increase linear growth rates at all scales, whereas variations in cross-field E × B drift velocity only affect small-scale instabilities. A formalism defining turbulent fluctuation energy for the system is introduced, and the turbulence is analyzed within this framework. This exercise serves as a useful verification test of the numerical simulations and also elucidates the physics underlying the ionospheric turbulence. Various physical mechanisms involved in the energetics are categorized as sources, sinks, nonlinear transfer, and cross-field coupling. The physics of the nonlinear transfer terms is studied to identify their roles in producing energy cascades, which explain the generation of small-scale structures that are stable in the linear regime. The theory of two-step energy cascading to generate the 3 m plasma irregularities in the equatorial electrojet is verified for the first time in the fluid regime. In addition, the nonlinearity of the system allows the possibility of an inverse energy cascade, potentially responsible for generating large-scale plasma structures at the top of the electrojet as found in different rocket and radar observations.

  8. Signal-to-noise performance analysis of streak tube imaging lidar systems. I. Cascaded model.

    Science.gov (United States)

    Yang, Hongru; Wu, Lei; Wang, Xiaopeng; Chen, Chao; Yu, Bing; Yang, Bin; Yuan, Liang; Wu, Lipeng; Xue, Zhanli; Li, Gaoping; Wu, Baoning

    2012-12-20

    Streak tube imaging lidar (STIL) is an active imaging system using a pulsed laser transmitter and a streak tube receiver to produce 3D range and intensity imagery. The STIL has recently attracted a great deal of interest and attention due to its advantages of wide azimuth field-of-view, high range and angle resolution, and high frame rate. This work investigates the signal-to-noise performance of STIL systems. A theoretical model for characterizing the signal-to-noise performance of the STIL system with an internal or external intensified streak tube receiver is presented, based on the linear cascaded systems theory of signal and noise propagation. The STIL system is decomposed into a series of cascaded imaging chains whose signal and noise transfer properties are described by the general (or the spatial-frequency dependent) noise factors (NFs). Expressions for the general NFs of the cascaded chains (or the main components) in the STIL system are derived. The work presented here is useful for the design and evaluation of STIL systems.

  9. Displacement cascades in Fesbnd Nisbnd Mnsbnd Cu alloys: RVP model alloys

    Science.gov (United States)

    Terentyev, D.; Zinovev, A.; Bonny, G.

    2016-07-01

    Primary damage due to displacement cascades (10-100 keV) has been assessed in Fesbnd 1%Mnsbnd 1%Ni-0.5%Cu and its binary alloys by molecular dynamics (MD), using a recent interatomic potential, specially developed to address features of the Fesbnd Mnsbnd Nisbnd Cu system in the dilute limit. The latter system represents the model matrix for reactor pressure vessel steels. The applied potential reproduces major interaction features of the solutes with point defects in the binary, ternary and quaternary dilute alloys. As compared to pure Fe, the addition of one type of a solute or all solutes together does not change the major characteristics of primary damage. However, the chemical structure of the self-interstitial defects is strongly sensitive to the presence and distribution of Mn and Cu in the matrix. 20 keV cascades were also studied in the Fesbnd Nisbnd Mnsbnd Cu matrix containing dislocation loops (with density of 1024 m-3 and size 2 nm). Two solute distributions were investigated, namely: a random one and one obtained by Metropolis Monte Carlo simulations from our previous work. The presence of the loops did not affect the defect production efficiency but slightly reduced the fraction of isolated self-interstitials and vacancies. The cascade event led to the transformation of the loops into ½ glissile configurations with a success rate of 10% in the matrix with random solute distribution, while all the pre-created loops remain stable if the alloy's distribution was applied using the Monte-Carlo method. This suggests that solute segregation to loops "stabilizes" the pre-existing loops against transformation or migration induced by collision cascades.

  10. Modified k-ωmodel using kinematic vorticity for corner separation in compressor cascades

    Institute of Scientific and Technical Information of China (English)

    LIU YangWei; YAN Hao; FANG Le; LU LiPeng; LI QiuShi; SHAO Liang

    2016-01-01

    A new method of modifying the conventional k-ω turbulence model for comer separation is proposed in this paper.The production term in the ω equation is modified using kinematic vorticity considering fluid rotation and deformation in complex geometric boundary conditions.The comer separation flow in linear compressor cascades is calculated using the original k-ω model,the modified k-ωmodel and the Reynolds stress model (RSM).The numerical results of the modified model are compared with the available experimental data,as well as the corresponding results of the original k-comodel and RSM.In terms of accuracy,the modified model,which significantly improves the performance of the original k-ω model for predicting comer separation,is quite competitive with the RSM.However,the modified model,which has considerably lower computational cost,is more robust than the RSM.

  11. Reading.

    Science.gov (United States)

    Gee, James Paul

    1992-01-01

    Explores what is meant by reading, noting that to read is to respond appropriately to a specific consensus centered on certain values and that the consensus is achieved among persons whose paths through life have come together with members of dominant discourses in society. (SLD)

  12. Mitigating cascades in sandpile models: an immunization strategy for systemic risk?

    Science.gov (United States)

    Scala, Antonio; Zlatić, Vinko; Caldarelli, Guido; D'Agostino, Gregorio

    2016-10-01

    We use a simple model of distress propagation (the sandpile model) to show how financial systems are naturally subject to the risk of systemic failures. Taking into account possible network structures among financial institutions, we investigate if simple policies can limit financial distress propagation to avoid system-wide crises, i.e. to dampen systemic risk. We therefore compare different immunization policies (i.e. targeted helps to financial institutions) and find that the information coming from the network topology allows to mitigate systemic cascades by targeting just few institutions.

  13. Elliptic flow in a hadron-string cascade model at 130 GeV energy

    Indian Academy of Sciences (India)

    P K Sahu; A Ohnishi; M Isse; N Otuka; S C Phatak

    2006-08-01

    We present the analysis of elliptic flow at $\\sqrt{s} = 130$ A GeV energy in a hadron-string cascade model. We find that the final hadronic yields are qualitatively described. The elliptic flow 2 is reasonably well-described at low transverse momentum (T < 1 GeV/c) in mid-central collisions. On the other hand, this model does not explain 2 at high T or in peripheral collisions and thus generally, it underestimates the elliptic flow at RHIC energy.

  14. A cascade model of information processing and encoding for retinal prosthesis

    Directory of Open Access Journals (Sweden)

    Zhi-jun Pei

    2016-01-01

    Full Text Available Retinal prosthesis offers a potential treatment for individuals suffering from photoreceptor degeneration diseases. Establishing biological retinal models and simulating how the biological retina convert incoming light signal into spike trains that can be properly decoded by the brain is a key issue. Some retinal models have been presented, ranking from structural models inspired by the layered architecture to functional models originated from a set of specific physiological phenomena. However, Most of these focus on stimulus image compression, edge detection and reconstruction, but do not generate spike trains corresponding to visual image. In this study, based on state-of-the-art retinal physiological mechanism, including effective visual information extraction, static nonlinear rectification of biological systems and neurons Poisson coding, a cascade model of the retina including the out plexiform layer for information processing and the inner plexiform layer for information encoding was brought forward, which integrates both anatomic connections and functional computations of retina. Using MATLAB software, spike trains corresponding to stimulus image were numerically computed by four steps: linear spatiotemporal filtering, static nonlinear rectification, radial sampling and then Poisson spike generation. The simulated results suggested that such a cascade model could recreate visual information processing and encoding functionalities of the retina, which is helpful in developing artificial retina for the retinally blind.

  15. A cascade model of information processing and encoding for retinal prosthesis

    Institute of Scientific and Technical Information of China (English)

    Zhi-jun Pei; Guan-xin Gao; Bo Hao; Qing-li Qiao; Hui-jian Ai

    2016-01-01

    Retinal prosthesis offers a potential treatment for individuals suffering from photoreceptor degeneration diseases. Establishing biological retinal models and simulating how the biological retina convert incoming light signal into spike trains that can be properly decoded by the brain is a key issue. Some retinal models have been presented, ranking from structural models inspired by the layered architecture to functional models originated from a set of speciifc physiological phenomena. However, Most of these focus on stimulus image com-pression, edge detection and reconstruction, but do not generate spike trains corresponding to visual image. In this study, based on state-of-the-art retinal physiological mechanism, including effective visual information extraction, static nonlinear rectiifcation of biological systems and neurons Poisson coding, a cascade model of the retina including the out plexiform layer for information processing and the inner plexiform layer for information encoding was brought forward, which integrates both anatomic connections and functional com-putations of retina. Using MATLAB software, spike trains corresponding to stimulus image were numerically computed by four steps:linear spatiotemporal ifltering, static nonlinear rectiifcation, radial sampling and then Poisson spike generation. The simulated results suggested that such a cascade model could recreate visual information processing and encoding functionalities of the retina, which is helpful in developing artiifcial retina for the retinally blind.

  16. The cascade model of teachers’ continuing professional development in Kenya: A time for change?

    Directory of Open Access Journals (Sweden)

    Harry Kipkemoi Bett

    2016-12-01

    Full Text Available Kenya is one of the countries whose teachers the UNESCO (2015 report cited as lacking curriculum support in the classroom. As is the case in many African countries, a large portion of teachers in Kenya enter the teaching profession when inadequately prepared, while those already in the field receive insufficient support in their professional lives. The cascade model has often been utilized in the country whenever need for teachers’ continuing professional development (TCPD has arisen, especially on a large scale. The preference for the model is due to, among others, its cost effectiveness and ability to reach out to many teachers within a short period of time. Many researchers have however cast aspersions with this model for its glaring shortcomings. On the contrary, TCPD programmes that are collaborative in nature and based on teachers’ contexts have been found to be more effective than those that are not. This paper briefly examines cases of the cascade model in Kenya, the challenges associated with this model and proposes the adoption of collaborative and institution-based models to mitigate these challenges. The education sectors in many nations in Africa, and those in the developing world will find the discussions here relevant.

  17. Information Theory Analysis of Cascading Process in a Synthetic Model of Fluid Turbulence

    Directory of Open Access Journals (Sweden)

    Massimo Materassi

    2014-02-01

    Full Text Available The use of transfer entropy has proven to be helpful in detecting which is the verse of dynamical driving in the interaction of two processes, X and Y . In this paper, we present a different normalization for the transfer entropy, which is capable of better detecting the information transfer direction. This new normalized transfer entropy is applied to the detection of the verse of energy flux transfer in a synthetic model of fluid turbulence, namely the Gledzer–Ohkitana–Yamada shell model. Indeed, this is a fully well-known model able to model the fully developed turbulence in the Fourier space, which is characterized by an energy cascade towards the small scales (large wavenumbers k, so that the application of the information-theory analysis to its outcome tests the reliability of the analysis tool rather than exploring the model physics. As a result, the presence of a direct cascade along the scales in the shell model and the locality of the interactions in the space of wavenumbers come out as expected, indicating the validity of this data analysis tool. In this context, the use of a normalized version of transfer entropy, able to account for the difference of the intrinsic randomness of the interacting processes, appears to perform better, being able to discriminate the wrong conclusions to which the “traditional” transfer entropy would drive.

  18. Depicting reading ability as an information literacy model.

    Directory of Open Access Journals (Sweden)

    Aurora Cuevas Cerveró

    2008-02-01

    Full Text Available Readers’ world has been lately challenged by significant changes, such as the increase on reading supply, the diversification of documentary media and the new types of reading, writing and communicating through the Internet. Such situation specially affects 21st century schools, which are evolving too slowly and so being relegated from their corresponding pre-eminent place as reading teachers and knowledge transmitters. The main goal of this article is to contribute mitigating such adverse effects on schools by proposing an information literacy skills model aimed for improving reading competency from the school library, which is considered a key element capable of turning reading again into an indispensable instrument in knowledge construction.

  19. A probabilistic sediment cascade model of sediment transfer in the Illgraben

    Science.gov (United States)

    Bennett, G. L.; Molnar, P.; McArdell, B. W.; Burlando, P.

    2014-02-01

    We present a probabilistic sediment cascade model to simulate sediment transfer in a mountain basin (Illgraben, Switzerland) where sediment is produced by hillslope landslides and rockfalls and exported out of the basin by debris flows and floods. The model conceptualizes the fluvial system as a spatially lumped cascade of connected reservoirs representing hillslope and channel storages where sediment goes through cycles of storage and remobilization by surface runoff. The model includes all relevant hydrological processes that lead to runoff formation in an Alpine basin, such as precipitation, snow accumulation, snowmelt, evapotranspiration, and soil water storage. Although the processes of sediment transfer and debris flow generation are described in a simplified manner, the model produces complex sediment discharge behavior which is driven by the availability of sediment and antecedent wetness conditions (system memory) as well as the triggering potential (climatic forcing). The observed probability distribution of debris flow volumes and their seasonality in 2000-2009 are reproduced. The stochasticity of hillslope sediment input is important for reproducing realistic sediment storage variability, although many details of the hillslope landslide triggering procedures are filtered out by the sediment transfer system. The model allows us to explicitly quantify the division into transport and supply-limited sediment discharge events. We show that debris flows may be generated for a wide range of rainfall intensities because of variable antecedent basin wetness and snowmelt contribution to runoff, which helps to understand the limitations of methods based on a single rainfall threshold for debris flow initiation in Alpine basins.

  20. Improved Intranuclear Cascade Models for the Codes CEM2k and LAQGSM

    CERN Document Server

    Mashnik, S G; Sierk, A J; Prael, R E

    2005-01-01

    An improved version of the Cascade-Exciton Model (CEM) of nuclear reactions implemented in the codes CEM2k and the Los Alamos version of the Quark-Gluon String Model (LAQGSM) has been developed recently at LANL to describe reactions induced by particles and nuclei at energies up to hundreds of GeV/nucleon for a number of applications. We present several improvements to the intranuclear cascade models used in CEM2k and LAQGSM developed recently to better describe the physics of nuclear reactions. First, we incorporate the photonuclear mode from CEM2k into LAQGSM to allow it to describe photonuclear reactions, not previously modeled there. Then, we develop new approximations to describe more accurately experimental elementary energy and angular distributions of secondary particles from hadron-hadron and photon-hadron interactions using available data and approximations published by other authors. Finally, to consider reactions involving very highly excited nuclei (E* > 2-3 MeV/A), we have incorporated into CEM2...

  1. Extended Intranuclear Cascade model for pickup reactions induced by 50-MeV-range protons

    Directory of Open Access Journals (Sweden)

    Uozumi Yusuke

    2016-01-01

    Full Text Available The intranuclear cascade model was investigated to explain (p, dx and (p, ax reactions at incident energies of around 50 MeV. Since these reactions are governed mainly by the direct pickup process, the model was expanded to include exclusive pickup processes leading to hole-state-excitations. The energy of the outgoing clusters is determined with single-particle energies of transferred nucleons, the reaction Q-value, and the recoil of the residual nucleus. The rescattering of the produced cluster inside the nucleus is treated within the intranuclear cascade model. The emission angle is given by the sum of momentum vectors of transferred nucleons in addition to the deflection at the nuclear surface, which was introduced to explain angular distributions of elastic scattering. Double differential cross sections of reactions were calculated and compared with experimental data. The proposed model showed a high predictive power over the wide range of emission energies and angles. The treatment ofthe cluster transport inside the nucleus was also verified.

  2. Fast modeling of flux trapping cascaded explosively driven magnetic flux compression generators.

    Science.gov (United States)

    Wang, Yuwei; Zhang, Jiande; Chen, Dongqun; Cao, Shengguang; Li, Da; Liu, Chebo

    2013-01-01

    To predict the performance of flux trapping cascaded flux compression generators, a calculation model based on an equivalent circuit is investigated. The system circuit is analyzed according to its operation characteristics in different steps. Flux conservation coefficients are added to the driving terms of circuit differential equations to account for intrinsic flux losses. To calculate the currents in the circuit by solving the circuit equations, a simple zero-dimensional model is used to calculate the time-varying inductance and dc resistance of the generator. Then a fast computer code is programmed based on this calculation model. As an example, a two-staged flux trapping generator is simulated by using this computer code. Good agreements are achieved by comparing the simulation results with the measurements. Furthermore, it is obvious that this fast calculation model can be easily applied to predict performances of other flux trapping cascaded flux compression generators with complex structures such as conical stator or conical armature sections and so on for design purpose.

  3. Competence-Oriented Decision Model for Optimizing the Operation of a Cascading Hydroelectric Power Reservoir

    Directory of Open Access Journals (Sweden)

    Tilahun Derib Asfaw

    2013-07-01

    Full Text Available The operation of the four Perak cascading reservoirs namely, Temenggor, Bersia, Kenering and Chenderoh analyzed using the newly developed genetic algorithm model. The reservoirs are located in the state of Perak of Peninsular Malaysia that used for hydroelectric power generation and flood mitigation. The hydroelectric potential of the cascading scheme is 578 MW. However, the actual annual average generation was 228 MW, which is about 39% of the potential. The research aimed to improve the annual average hydroelectric power generation. The result of the fitness value used to select the optimal option from the test of eight model runs options. After repeated runs of the optimal option, the best model parameters are found. Therefore, optimality achieved at population size of 150, crossover probability of 0.75 and generation number of 60. The operation of GA model produced an additional of 12.17 MW per day. The additional power is found with the same total annual volume of release and similar natural inflow pattern. The additional hydroelectric power can worth over 22 million Ringgit Malaysia per year. In addition, it plays a significant role on the growing energy needs of the country.

  4. A Model of Reading Teaching for University EFL Students: Need Analysis and Model Design

    Science.gov (United States)

    Hamra, Arifuddin; Syatriana, Eny

    2012-01-01

    This study designed a model of teaching reading for university EFL students based on the English curriculum at the Faculty of Languages and Literature and the concept of the team-based learning in order to improve the reading comprehension of the students. What kind of teaching model can help students to improve their reading comprehension? The…

  5. Fluid-structure coupling in the guide vanes cascade of a pump-turbine scale model

    Energy Technology Data Exchange (ETDEWEB)

    Roth, S; Hasmatuchi, V; Botero, F; Farhat, M; Avellan, F, E-mail: steven.roth@epfl.c [Laboratory for Hydraulic Machines, Ecole Polytechnique Federale de Lausanne Av. de Cour 33bis, Lausanne, 1007 (Switzerland)

    2010-08-15

    The present study concerns fluid-structure coupling phenomena occurring in a guide vane cascade of a pump-turbine scale model placed in the EPFL PF3 test rig. An advanced instrument set is used to monitor both vibrating structures and the surrounding flow. The paper highlights the interaction between vibrating guide vanes and the flow behavior. The pressure fluctuations in the stay vanes region are found to be strongly influenced by the amplitude of the vibrating guide vanes. Moreover, the flow induces different hydrodynamic damping on the vibrating guide vanes depending on the operating point of the pump-turbine.

  6. Developmental, Component-Based Model of Reading Fluency: An Investigation of Predictors of Word-Reading Fluency, Text-Reading Fluency, and Reading Comprehension

    OpenAIRE

    Kim, Young-Suk Grace

    2015-01-01

    The primary goal was to expand our understanding of text reading fluency (efficiency or automaticity)—how its relation to other constructs (e.g., word reading fluency and reading comprehension) changes over time and how it is different from word reading fluency and reading comprehension. We examined (1) developmentally changing relations among word reading fluency, listening comprehension, text reading fluency, and reading comprehension; (2) the relation of reading comprehension to text readi...

  7. Emotion : mod\\`ele d'appraisal-coping pour le probl\\`eme des Cascades

    CERN Document Server

    Mahboub, Karim; Jay, Véronique; Clément, Evelyne

    2009-01-01

    Modeling emotion has become a challenge nowadays. Therefore, several models have been produced in order to express human emotional activity. However, only a few of them are currently able to express the close relationship existing between emotion and cognition. An appraisal-coping model is presented here, with the aim to simulate the emotional impact caused by the evaluation of a particular situation (appraisal), along with the consequent cognitive reaction intended to face the situation (coping). This model is applied to the ?Cascades? problem, a small arithmetical exercise designed for ten-year-old pupils. The goal is to create a model corresponding to a child's behavior when solving the problem using his own strategies.

  8. A Probabilistic Genome-Wide Gene Reading Frame Sequence Model

    DEFF Research Database (Denmark)

    Have, Christian Theil; Mørk, Søren

    We introduce a new type of probabilistic sequence model, that model the sequential composition of reading frames of genes in a genome. Our approach extends gene finders with a model of the sequential composition of genes at the genome-level -- effectively producing a sequential genome annotation...... and are evaluated by the effect on prediction performance. Since bacterial gene finding to a large extent is a solved problem it forms an ideal proving ground for evaluating the explicit modeling of larger scale gene sequence composition of genomes. We conclude that the sequential composition of gene reading frames...... as output. The model can be used to obtain the most probable genome annotation based on a combination of i: a gene finder score of each gene candidate and ii: the sequence of the reading frames of gene candidates through a genome. The model --- as well as a higher order variant --- is developed and tested...

  9. iCRESTRIGRS: a coupled modeling system for cascading flood-landslide disaster forecasting

    Science.gov (United States)

    Zhang, Ke; Xue, Xianwu; Hong, Yang; Gourley, Jonathan J.; Lu, Ning; Wan, Zhanming; Hong, Zhen; Wooten, Rick

    2016-12-01

    Severe storm-triggered floods and landslides are two major natural hazards in the US, causing property losses of USD 6 billion and approximately 110-160 fatalities per year nationwide. Moreover, floods and landslides often occur in a cascading manner, posing significant risk and leading to losses that are significantly greater than the sum of the losses from the hazards when acting separately. It is pertinent to couple hydrological and geotechnical modeling processes to an integrated flood-landslide cascading disaster modeling system for improved disaster preparedness and hazard management. In this study, we developed the iCRESTRIGRS model, a coupled flash flood and landslide initiation modeling system, by integrating the Coupled Routing and Excess STorage (CREST) model with the physically based Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability (TRIGRS) landslide model. The iCRESTRIGRS system is evaluated in four river basins in western North Carolina that experienced a large number of floods, landslides and debris flows triggered by heavy rainfall from Hurricane Ivan during 16-18 September 2004. The modeled hourly hydrographs at four USGS gauge stations show generally good agreement with the observations during the entire storm period. In terms of landslide prediction in this case study, the coupled model has a global accuracy of 98.9 % and a true positive rate of 56.4 %. More importantly, it shows an improved predictive capability for landslides relative to the stand-alone TRIGRS model. This study highlights the important physical connection between rainfall, hydrological processes and slope stability, and provides a useful prototype model system for operational forecasting of flood and landslide.

  10. Cascading uncertainties in flood inundation models to uncertain estimates of damage and loss

    Science.gov (United States)

    Fewtrell, Timothy; Michel, Gero; Ntelekos, Alexandros; Bates, Paul

    2010-05-01

    The complexity of flood processes, particularly in urban environments, and the difficulties of collecting data during flood events, presents significant and particular challenges to modellers, especially when considering large geographic areas. As a result, the modelling process incorporates a number of areas of uncertainty during model conceptualisation, construction and evaluation. There is a wealth of literature detailing the relative magnitudes of uncertainties in numerical flood input data (e.g. boundary conditions, model resolution and friction specification) for a wide variety of flood inundation scenarios (e.g. fluvial inundation and surface water flooding). Indeed, recent UK funded projects (e.g. FREE) have explicitly examined the effect of cascading uncertainties in ensembles of GCM output through rainfall-runoff models to hydraulic flood inundation models. However, there has been little work examining the effect of cascading uncertainties in flood hazard ensembles to estimates of damage and loss, the quantity of interest when assessing flood risk. Furthermore, vulnerability is possibly the largest area of uncertainty for (re-)insurers as in-depth and reliable of knowledge of portfolios is difficult to obtain. Insurance industry CAT models attempt to represent a credible range of flood events over large geographic areas and as such examining all sources of uncertainty is not computationally tractable. However, the insurance industry is also marked by a trend towards an increasing need to understand the variability in flood loss estimates derived from these CAT models. In order to assess the relative importance of uncertainties in flood inundation models and depth/damage curves, hypothetical 1-in-100 and 1-in-200 year return period flood events are propagated through the Greenwich embayment in London, UK. Errors resulting from topographic smoothing, friction specification and inflow boundary conditions are cascaded to form an ensemble of flood levels and

  11. Lenses on reading an introduction to theories and models

    CERN Document Server

    Tracey, Diane H

    2017-01-01

    Widely adopted as an ideal introduction to the major models of reading, this text guides students to understand and facilitate children's literacy development. Coverage encompasses the full range of theories that have informed reading instruction and research, from classical thinking to cutting-edge cognitive, social learning, physiological, and affective perspectives. Readers learn how theory shapes instructional decision making and how to critically evaluate the assumptions and beliefs that underlie their own teaching. Pedagogical features include framing and discussion questions, learning a

  12. Effective Reading and Writing Instruction: A Focus on Modeling

    Science.gov (United States)

    Regan, Kelley; Berkeley, Sheri

    2012-01-01

    When providing effective reading and writing instruction, teachers need to provide explicit modeling. Modeling is particularly important when teaching students to use cognitive learning strategies. Examples of how teachers can provide specific, explicit, and flexible instructional modeling is presented in the context of two evidence-based…

  13. Modelling and control of broadband traffic using multiplicative multifractal cascades

    Indian Academy of Sciences (India)

    P Murali Krishna; Vikram M Gadre; Uday B Desai

    2002-12-01

    We present the results on the modelling and synthesis of broadband traffic processes namely ethernet inter-arrival times using the VVGM (variable variance gaussian multiplier) multiplicative multifractal model. This model is shown to be more appropriate for modelling network traffic which possess time varying scaling/self-similarity and burstiness. The model gives a simple and efficient technique to synthesise Ethernet inter-arrival times. The results of the detailed statistical and multifractal analysis performed on the original and the synthesised traces are presented and the performance is compared with other models in the literature, such as the Poisson process, and the Multifractal Wavelet Model (MWM) process. It is also shown empirically that a single server queue preserves the multifractal character of the process by analysing its inter-departure process when fed with the multifractal traces. The result of the existence of a global-scaling exponent for multifractal cascades and its application in queueing theory are discussed. We propose tracking and control algorithms for controlling network congestion with bursty traffic modelled by multifractal cascade processes, characterised by the Holder exponents, the value of which at an interval indicates the burstiness in the traffic at that point. This value has to be estimated and used for the estimation of the congestion and predictive control of the traffic in broadband networks. The estimation can be done by employing wavelet transforms and a Kalman filter based predictor for predicting the burstiness of the traffic.

  14. A stochastical event-based continuous time step rainfall generator based on Poisson rectangular pulse and microcanonical random cascade models

    Science.gov (United States)

    Pohle, Ina; Niebisch, Michael; Zha, Tingting; Schümberg, Sabine; Müller, Hannes; Maurer, Thomas; Hinz, Christoph

    2017-04-01

    Rainfall variability within a storm is of major importance for fast hydrological processes, e.g. surface runoff, erosion and solute dissipation from surface soils. To investigate and simulate the impacts of within-storm variabilities on these processes, long time series of rainfall with high resolution are required. Yet, observed precipitation records of hourly or higher resolution are in most cases available only for a small number of stations and only for a few years. To obtain long time series of alternating rainfall events and interstorm periods while conserving the statistics of observed rainfall events, the Poisson model can be used. Multiplicative microcanonical random cascades have been widely applied to disaggregate rainfall time series from coarse to fine temporal resolution. We present a new coupling approach of the Poisson rectangular pulse model and the multiplicative microcanonical random cascade model that preserves the characteristics of rainfall events as well as inter-storm periods. In the first step, a Poisson rectangular pulse model is applied to generate discrete rainfall events (duration and mean intensity) and inter-storm periods (duration). The rainfall events are subsequently disaggregated to high-resolution time series (user-specified, e.g. 10 min resolution) by a multiplicative microcanonical random cascade model. One of the challenges of coupling these models is to parameterize the cascade model for the event durations generated by the Poisson model. In fact, the cascade model is best suited to downscale rainfall data with constant time step such as daily precipitation data. Without starting from a fixed time step duration (e.g. daily), the disaggregation of events requires some modifications of the multiplicative microcanonical random cascade model proposed by Olsson (1998): Firstly, the parameterization of the cascade model for events of different durations requires continuous functions for the probabilities of the multiplicative

  15. Composite and Cascaded Generalized-K Fading Channel Modeling and Their Diversity and Performance Analysis

    KAUST Repository

    Ansari, Imran Shafique

    2010-12-01

    The introduction of new schemes that are based on the communication among nodes has motivated the use of composite fading models due to the fact that the nodes experience different multipath fading and shadowing statistics, which subsequently determines the required statistics for the performance analysis of different transceivers. The end-to-end signal-to-noise-ratio (SNR) statistics plays an essential role in the determination of the performance of cascaded digital communication systems. In this thesis, a closed-form expression for the probability density function (PDF) of the end-end SNR for independent but not necessarily identically distributed (i.n.i.d.) cascaded generalized-K (GK) composite fading channels is derived. The developed PDF expression in terms of the Meijer-G function allows the derivation of subsequent performance metrics, applicable to different modulation schemes, including outage probability, bit error rate for coherent as well as non-coherent systems, and average channel capacity that provides insights into the performance of a digital communication system operating in N cascaded GK composite fading environment. Another line of research that was motivated by the introduction of composite fading channels is the error performance. Error performance is one of the main performance measures and derivation of its closed-form expression has proved to be quite involved for certain systems. Hence, in this thesis, a unified closed-form expression, applicable to different binary modulation schemes, for the bit error rate of dual-branch selection diversity based systems undergoing i.n.i.d. GK fading is derived in terms of the extended generalized bivariate Meijer G-function.

  16. Niagara Falls Cascade Model for Interstellar Energetic Ions in the Heliosheath

    Science.gov (United States)

    Cooper, John F.

    The origin of anomalous cosmic ray ions has long been assumed to be heliospheric pickup ion production from interstellar neutrals and acceleration at the solar wind termination shock. The Voyager-1 shock crossing showed a well-defined boundary for sharply increased keV ion fluxes in the heliosheath but no sign of local acceleration. Ion flux spectra at keV to MeV energies are instead unfolding with outward passage to approximate the E(-1.5) power-law expected for compressional magnetic tubulence. This spectrum provides excellent connection over many energy decades of a maxwellian distribution for local interstellar plasma ions to well-known flux spectra of high energy galactic ions at GeV energies. The Niagara Falls cascade model is proposed that the heliosheath is a transitional region for direct entry of ions from the local interstellar ‘river’ through a permeable heliopause into the supersonic outer heliosphere. As Voyager-1 moves outwards in the heliosheath to the heliopause, energy-dependent transport features can appear in the transitional 0.01 - 1 GeV/n energy band but otherwise a general unfolding to the interstellar limiting spectrum should continue by this model. Spectral regions then become dominated by bulk plasma flow at low energy, cascade transport at intermediate energies, and interstellar shock acceleration at higher energies.

  17. Sediment cascade modelling for stochastic torrential sediment transfers forecasting in a changing alpine climate

    Science.gov (United States)

    Rudaz, Benjamin; Bardou, Eric; Jaboyedoff, Michel

    2015-04-01

    Alpine ephemeral streams act as links between high altitude erosional processes, slope movements and valley-floor fluvial systems or fan storage. Anticipating future mass wasting from these systems is crucial for hazard mitigation measures. Torrential activity is highly stochastic, with punctual transfers separating long periods of calm, during which the system evolves internally and recharges. Changes can originate from diffuse (rock faces, sheet erosion of bared moraines), concentrated external sources (rock glacier front, slope instabilities) or internal transfers (bed incision or aggradation). The proposed sediment cascade model takes into account those different processes and calculates sediment transfer from the slope to the channel reaches, and then propagates sediments downstream. The two controlling parameters are precipitation series (generated from existing rain gauge data using Gumbel and Extreme Probability Distribution functions) and temperature (generated from local meteorological stations data and IPCC scenarios). Snow accumulation and melting, and thus runoff can then be determined for each subsystem, to account for different altitudes and expositions. External stocks and sediment sources have each a specific response to temperature and precipitation. For instance, production from rock faces is dependent on frost-thaw cycles, in addition to precipitations. On the other hand, landslide velocity, and thus sediment production is linked to precipitations over longer periods of time. Finally, rock glaciers react to long-term temperature trends, but are also prone to sudden release of material during extreme rain events. All those modules feed the main sediment cascade model, constructed around homogeneous torrent reaches, to and from which sediments are transported by debris flows and bedload transport events. These events are determined using a runoff/erosion curve, with a threshold determining the occurrence of debris flows in the system. If a debris

  18. Geant4 Hadronic Cascade Models and CMS Data Analysis : Computational Challenges in the LHC era

    CERN Document Server

    Heikkinen, Aatos

    This work belongs to the field of computational high-energy physics (HEP). The key methods used in this thesis work to meet the challenges raised by the Large Hadron Collider (LHC) era experiments are object-orientation with software engineering, Monte Carlo simulation, the computer technology of clusters, and artificial neural networks. The first aspect discussed is the development of hadronic cascade models, used for the accurate simulation of medium-energy hadron-nucleus reactions, up to 10 GeV. These models are typically needed in hadronic calorimeter studies and in the estimation of radiation backgrounds. Various applications outside HEP include the medical field (such as hadron treatment simulations), space science (satellite shielding), and nuclear physics (spallation studies). Validation results are presented for several significant improvements released in Geant4 simulation tool, and the significance of the new models for computing in the Large Hadron Collider era is estimated. In particular, we es...

  19. Beyond the Parton Cascade Model: Klaus Kinder-Geiger and VNI

    Science.gov (United States)

    Müller, Berndt

    1999-07-01

    I review Klaus Kinder-Geiger's contributions to the physics of relativistic heavy ion collisions, in particular, the Parton Cascade Model. Klaus developed this model in order to provide a QCD-based description of nucleus-nucleus reactions at high energies such as they will soon become available at the Brookhaven Relativistic Heavy Ion Collider. The PCM describes the collision dynamics within the early and dense phase of the reaction in terms of the relativistic, probabilistic transport of perturbative excitations (partons) of the QCD vacuum. I will present an overview of the current state of the numerical implementations of this model, as well as its predictions for nuclear collisions at RHIC and LHC.

  20. Beyond the Parton Cascade Model Klaus Kinder-Geiger and VNI

    CERN Document Server

    Müller, B

    1999-01-01

    I review Klaus Kinder-Geiger's contributions to the physics of relativistic heavy ion collisions, in particular, the Parton Cascade Model. Klaus developed this model in order to provide a QCD-based description of nucleus-nucleus reactions at high energies such as they will soon become available at the Brookhaven Relativistic Heavy Ion Collider. The PCM describes the collision dynamics within the early and dense phase of the reaction in terms of the relativistic, probabilistic transport of perturbative excitations (partons) of the QCD vacuum. I will present an overview of the current state of the numerical implementations of this model, as well as its predictions for nuclear collisions at RHIC and LHC.

  1. MAWRID: A Model of Arabic Word Reading in Development.

    Science.gov (United States)

    Saiegh-Haddad, Elinor

    2017-07-01

    This article offers a model of Arabic word reading according to which three conspicuous features of the Arabic language and orthography shape the development of word reading in this language: (a) vowelization/vocalization, or the use of diacritical marks to represent short vowels and other features of articulation; (b) morphological structure, namely, the predominance and transparency of derivational morphological structure in the linguistic and orthographic representation of the Arabic word; and (c) diglossia, specifically, the lexical and lexico-phonological distance between the spoken and the standard forms of Arabic words. It is argued that the triangulation of these features governs the acquisition and deployment of reading mechanisms across development. Moreover, the difficulties that readers encounter in their journey from beginning to skilled reading may be better understood if evaluated within these language-specific features of Arabic language and orthography.

  2. Learning to Read a Semitic Abjad: The Triplex Model of Hebrew Reading Development.

    Science.gov (United States)

    Share, David L; Bar-On, Amalia

    2017-07-01

    We introduce a model of Hebrew reading development that emphasizes both the universal and script-specific aspects of learning to read a Semitic abjad. At the universal level, the study of Hebrew reading acquisition offers valuable insights into the fundamental dilemmas of all writing systems-balancing the competing needs of the novice versus the expert reader (Share, 2008). At the script-specific level, pointed Hebrew initially employs supplementary vowel signs, providing the beginning reader a consistent, phonologically well-specified script while helping the expert-to-be unitize words and morphemes via (consonantal) spelling constancy. A major challenge for the developing Hebrew reader is negotiating the transition from pointed to unpointed Hebrew, with its abundance of homographs. Our triplex model emphasizes three phases of early Hebrew reading development: a progression from lower-order, phonological (sublexical) sequential spelling-to-sound translation (Phase 1, Grade 1) to higher-order, string-level (lexical) lexico-morpho-orthographic processing (Phase 2, Grade 2) followed, in the upper elementary grades, by a supralexical contextual level (Phase 3) essential for dealing with the pervasive homography of unpointed Hebrew.

  3. The cascade of uncertainty in modeling the impacts of climate change on Europe's forests

    Science.gov (United States)

    Reyer, Christopher; Lasch-Born, Petra; Suckow, Felicitas; Gutsch, Martin

    2015-04-01

    Projecting the impacts of global change on forest ecosystems is a cornerstone for designing sustainable forest management strategies and paramount for assessing the potential of Europe's forest to contribute to the EU bioeconomy. Research on climate change impacts on forests relies to a large extent on model applications along a model chain from Integrated Assessment Models to General and Regional Circulation Models that provide important driving variables for forest models. Or to decision support systems that synthesize findings of more detailed forest models to inform forest managers. At each step in the model chain, model-specific uncertainties about, amongst others, parameter values, input data or model structure accumulate, leading to a cascade of uncertainty. For example, climate change impacts on forests strongly depend on the in- or exclusion of CO2-effects or on the use of an ensemble of climate models rather than relying on one particular climate model. In the past, these uncertainties have not or only partly been considered in studies of climate change impacts on forests. This has left managers and decision-makers in doubt of how robust the projected impacts on forest ecosystems are. We deal with this cascade of uncertainty in a structured way and the objective of this presentation is to assess how different types of uncertainties affect projections of the effects of climate change on forest ecosystems. To address this objective we synthesized a large body of scientific literature on modeled productivity changes and the effects of extreme events on plant processes. Furthermore, we apply the process-based forest growth model 4C to forest stands all over Europe and assess how different climate models, emission scenarios and assumptions about the parameters and structure of 4C affect the uncertainty of the model projections. We show that there are consistent regional changes in forest productivity such as an increase in NPP in cold and wet regions while

  4. Examining the Simple View of Reading Model for United States High School Spanish Students

    Science.gov (United States)

    Sparks, Richard; Patton, Jon

    2016-01-01

    The Simple View of Reading (SVR) model, which posits that reading comprehension is the product of word decoding and language comprehension that make independent contributions to reading skill, has been found to explain the acquisition of first language (L1) reading and second language (L2) reading in young English language learners (ELLs).…

  5. Time to smell: a cascade model of human olfactory perception based on response-time (RT) measurement.

    Science.gov (United States)

    Olofsson, Jonas K

    2014-01-01

    The timing of olfactory behavioral decisions may provide an important source of information about how the human olfactory-perceptual system is organized. This review integrates results from olfactory response-time (RT) measurements from a perspective of mental chronometry. Based on these findings, a new cascade model of human olfaction is presented. Results show that main perceptual decisions are executed with high accuracy within about 1~s of sniff onset. The cascade model proposes the existence of distinct processing stages within this brief time-window. According to the cascade model, different perceptual features become accessible to the perceiver at different time-points, and the output of earlier processing stages provides the input for later processing stages. The olfactory cascade starts with detecting the odor, which is followed by establishing an odor object. The odor object, in turn, triggers systems for determining odor valence and edibility. Evidence for the cascade model comes from studies showing that RTs for odor valence and edibility assessment are predicted by the shorter RTs needed to establish the odor object. Challenges for future research include innovative task designs for olfactory RT experiments and the integration of the behavioral processing sequence into the underlying cortical processes using complementary RT measures and neuroimaging methods.

  6. A photon splitting cascade model of soft gamma-ray repeaters

    CERN Document Server

    Harding, A K; Harding, Alice K; Baring, Matthew G

    1996-01-01

    The spectra of soft gamma-ray repeaters (SGRs), with the exception of the March 5, 1979 main burst, are characterized by high-energy cutoffs around 30 keV and low-energy turnovers that are much steeper than a Wien spectrum. Baring (1995) found that the spectra of cascades due to photon splitting in a very strong, homogeneous magnetic field can soften spectra and produce good fits to the soft spectra of SGRs. Magnetic field strengths somewhat above the QED critical field strength B_{\\rm cr}, where B_{\\rm cr} = 4.413 \\times 10^{13} G, is required to produce cutoffs at 30-40 keV. We have improved upon this model by computing Monte Carlo photon splitting cascade spectra in a neutron star dipole magnetic field, including effects of curved space-time in a Schwarzschild metric. We investigate spectra produced by photons emitted at different locations and observer angles. We find that the general results of Baring hold for surface emission throughout most of the magnetosphere, but that emission in equatorial regions ...

  7. Optical feedback effects on terahertz quantum cascade lasers: modelling and applications

    Science.gov (United States)

    Rakić, Aleksandar D.; Lim, Yah Leng; Taimre, Thomas; Agnew, Gary; Qi, Xiaoqiong; Bertling, Karl; Han, She; Wilson, Stephen J.; Kundu, Iman; Grier, Andrew; Ikonić, Zoran; Valavanis, Alexander; Demić, Aleksandar; Keeley, James; Li, Lianhe H.; Linfield, Edmund H.; Davies, A. Giles; Harrison, Paul; Ferguson, Blake; Walker, Graeme; Prow, Tarl; Indjin, Dragan; Soyer, H. Peter

    2016-11-01

    Terahertz (THz) quantum cascade lasers (QCLs) are compact sources of radiation in the 1-5 THz range with significant potential for applications in sensing and imaging. Laser feedback interferometry (LFI) with THz QCLs is a technique utilizing the sensitivity of the QCL to the radiation reflected back into the laser cavity from an external target. We will discuss modelling techniques and explore the applications of LFI in biological tissue imaging and will show that the confocal nature of the QCL in LFI systems, with their innate capacity for depth sectioning, makes them suitable for skin diagnostics with the well-known advantages of more conventional confocal microscopes. A demonstration of discrimination of neoplasia from healthy tissue using a THz, LFI-based system in the context of melanoma is presented using a transgenic mouse model.

  8. Multiscale Equatorial Electrojet Turbulence: Energy Conservation, Coupling, and Cascades in a Baseline 2-D Fluid Model

    CERN Document Server

    Hassan, Ehab; Morrison, P J; Horton, W

    2016-01-01

    Progress in understanding the coupling between plasma instabilities in the equatorial electrojet based on a unified fluid model is reported. A deeper understanding of the linear and nonlinear evolution and the coupling of the gradient-drift and Farley-Buneman instabilities is achieved by studying the e?ect of di?erent combinations of the density-gradient scale-lengths (Ln) and cross-?eld (E?B) drifts on the plasma turbulence. Mechanisms and channels of energy transfer are illucidated for these multiscale instabilities. Energy for the uni?ed model is examined, including the injected, conservative redistribution (between ?elds and scales), and ultimate dissipation. Various physical mechanisms involved in the energetics are categorized as sources, sinks, nonlinear transfer, and coupling to show that the system satisfies the fundamental law of energy Oonservation. The physics of the nonlinear transfer terms is studied to identify their roles in producing energy cascades { the transference of energy from the domin...

  9. Rate equations model and optical external efficiency of optically pumped electrically driven terahertz quantum cascade lasers

    Science.gov (United States)

    Hamadou, A.; Thobel, J.-L.; Lamari, S.

    2016-10-01

    A four level rate equations model for a terahertz optically pumped electrically driven quantum cascade laser is here introduced and used to model the system both analytically and numerically. In the steady state, both in the presence and absence of the terahertz optical field, we solve the resulting nonlinear system of equations and obtain closed form expressions for the levels occupation, population inversion as well as the mid-infrared pump threshold intensity in terms of the device parameters. We also derive, for the first time for this system, an analytical formula for the optical external efficiency and analyze the simultaneous effects of the cavity length and pump intensity on it. At moderate to high pump intensities, we find that the optical external efficiency scales roughly as the reciprocal of the cavity length.

  10. Hard state of the urban canopy layer turbulence and its self-similar multiplicative cascade models

    Institute of Scientific and Technical Information of China (English)

    HU; Fei; CHENG; Xueling; ZHAO; Songnian; QUAN; Lihong

    2005-01-01

    It is found by experiment that under the thermal convection condition, the temperature fluctuation in the urban canopy layer turbulence has the hard state character, and the temperature difference between two points has the exponential probability density function distribution. At the same time, the turbulent energy dissipation rate fits the log-normal distribution, and is in accord with the hypothesis proposed by Kolmogorov in 1962 and lots of reported experimental results. In this paper, the scaling law of hard state temperature n order structure function is educed by the self-similar multiplicative cascade models. The theory formula is Sn = n/3μ{n(n+6)/72+[2lnn!-nln2]/2ln6}, and μ Is intermittent exponent. The formula can fit the experimental results up to order 8 exponents, is superior to the predictions by the Kolmogorov theory, the β And log-normal model.

  11. $K^{+}$ momentum spectrum from $(K^{-},K^{+})$ reactions in intranuclear cascade model

    CERN Document Server

    Nara, Y; Harada, T; Engel, A

    1996-01-01

    In a framework of intranuclear cascade (INC) type calculation, we study a momentum spectrum in reactions \\KK at a beam momentum of 1.65 GeV/c. INC model calculations are compared with the relativistic impulse approximation (RIA) calculations to perform the detailed study of the reaction mechanism. We find that the INC model can reproduce the experimental data on various targets. Especially, in the low-momentum region, the forward-angle cross sections of the $(K^-,K^+)$ reaction on from light to heavy targets are consistently explained with the two-step strangeness exchange and production processes with various intermediate mesons, and $\\phi$, $a_0$ and $f_0$ productions and their decay into $K^+K^-$. In the two-step processes, inclusion of meson and hyperon resonances is found to be essential.

  12. Cascading Cosmology

    CERN Document Server

    Agarwal, Nishant; Khoury, Justin; Trodden, Mark

    2009-01-01

    We develop a fully covariant, well-posed 5D effective action for the 6D cascading gravity brane-world model, and use this to study cosmological solutions. We obtain this effective action through the 6D decoupling limit, in which an additional scalar degree mode, \\pi, called the brane-bending mode, determines the bulk-brane gravitational interaction. The 5D action obtained this way inherits from the sixth dimension an extra \\pi self-interaction kinetic term. We compute appropriate boundary terms, to supplement the 5D action, and hence derive fully covariant junction conditions and the 5D Einstein field equations. Using these, we derive the cosmological evolution induced on a 3-brane moving in a static bulk. We study the strong- and weak-coupling regimes analytically in this static ansatz, and perform a complete numerical analysis of our solution. Although the cascading model can generate an accelerating solution in which the \\pi field comes to dominate at late times, the presence of a critical singularity prev...

  13. Developmental, Component-Based Model of Reading Fluency: An Investigation of Predictors of Word-Reading Fluency, Text-Reading Fluency, and Reading Comprehension

    Science.gov (United States)

    Kim, Young-Suk Grace

    2015-01-01

    The primary goal was to expand our understanding of text reading fluency (efficiency or automaticity)—how its relation to other constructs (e.g., word reading fluency and reading comprehension) changes over time and how it is different from word reading fluency and reading comprehension. We examined (1) developmentally changing relations among word reading fluency, listening comprehension, text reading fluency, and reading comprehension; (2) the relation of reading comprehension to text reading fluency; (3) unique emergent literacy predictors (i.e., phonological awareness, orthographic awareness, morphological awareness, letter name knowledge, vocabulary) of text reading fluency vs. word reading fluency; and (4) unique language and cognitive predictors (e.g., vocabulary, grammatical knowledge, theory of mind) of text reading fluency vs. reading comprehension. These questions were addressed using longitudinal data (two timepoints; Mean age = 5;24 & 6;08) from Korean-speaking children (N = 143). Results showed that listening comprehension was related to text reading fluency at time 2, but not at time 1. At both times text reading fluency was related to reading comprehension, and reading comprehension was related to text reading fluency over and above word reading fluency and listening comprehension. Orthographic awareness was related to text reading fluency over and above other emergent literacy skills and word reading fluency. Vocabulary and grammatical knowledge were independently related to text reading fluency and reading comprehension whereas theory of mind was related to reading comprehension, but not text reading fluency. These results reveal developmental nature of relations and mechanism of text reading fluency in reading development. PMID:26435550

  14. Developmental, Component-Based Model of Reading Fluency: An Investigation of Predictors of Word-Reading Fluency, Text-Reading Fluency, and Reading Comprehension.

    Science.gov (United States)

    Kim, Young-Suk Grace

    2015-01-01

    The primary goal was to expand our understanding of text reading fluency (efficiency or automaticity)-how its relation to other constructs (e.g., word reading fluency and reading comprehension) changes over time and how it is different from word reading fluency and reading comprehension. We examined (1) developmentally changing relations among word reading fluency, listening comprehension, text reading fluency, and reading comprehension; (2) the relation of reading comprehension to text reading fluency; (3) unique emergent literacy predictors (i.e., phonological awareness, orthographic awareness, morphological awareness, letter name knowledge, vocabulary) of text reading fluency vs. word reading fluency; and (4) unique language and cognitive predictors (e.g., vocabulary, grammatical knowledge, theory of mind) of text reading fluency vs. reading comprehension. These questions were addressed using longitudinal data (two timepoints; Mean age = 5;24 & 6;08) from Korean-speaking children (N = 143). Results showed that listening comprehension was related to text reading fluency at time 2, but not at time 1. At both times text reading fluency was related to reading comprehension, and reading comprehension was related to text reading fluency over and above word reading fluency and listening comprehension. Orthographic awareness was related to text reading fluency over and above other emergent literacy skills and word reading fluency. Vocabulary and grammatical knowledge were independently related to text reading fluency and reading comprehension whereas theory of mind was related to reading comprehension, but not text reading fluency. These results reveal developmental nature of relations and mechanism of text reading fluency in reading development.

  15. Lenses on Reading An Introduction to Theories and Models

    CERN Document Server

    Tracey, Diane H

    2012-01-01

    This widely adopted text explores key theories and models that frame reading instruction and research. Readers learn why theory matters in designing and implementing high-quality instruction and research; how to critically evaluate the assumptions and beliefs that guide their own work; and what can be gained by looking at reading through multiple theoretical lenses. For each theoretical model, classroom applications are brought to life with engaging vignettes and teacher reflections. Research applications are discussed and illustrated with descriptions of exemplary studies. New to This Edition

  16. An information propagation model considering incomplete reading behavior in microblog

    Science.gov (United States)

    Su, Qiang; Huang, Jiajia; Zhao, Xiande

    2015-02-01

    Microblog is one of the most popular communication channels on the Internet, and has already become the third largest source of news and public opinions in China. Although researchers have studied the information propagation in microblog using the epidemic models, previous studies have not considered the incomplete reading behavior among microblog users. Therefore, the model cannot fit the real situations well. In this paper, we proposed an improved model entitled Microblog-Susceptible-Infected-Removed (Mb-SIR) for information propagation by explicitly considering the user's incomplete reading behavior. We also tested the effectiveness of the model using real data from Sina Microblog. We demonstrate that the new proposed model is more accurate in describing the information propagation in microblog. In addition, we also investigate the effects of the critical model parameters, e.g., reading rate, spreading rate, and removed rate through numerical simulations. The simulation results show that, compared with other parameters, reading rate plays the most influential role in the information propagation performance in microblog.

  17. Evaluation of random cascade hierarchical and statistical arrangement model in disaggregation of SMOS soil moisture

    Science.gov (United States)

    Hosseini, M.; Magagi, R.; Goita, K.

    2013-12-01

    Soil moisture is an important parameter in hydrology that can be derived from remote sensing. In different studies, it was shown that optical-thermal, active and passive microwave remote sensing data can be used for soil moisture estimation. However, the most promising approach to estimate soil moisture in large areas is passive microwave radiometry. Global estimation of soil moisture is now operational by using remote sensing techniques. The Advanced Microwave Scanning Radiometer-Earth Observing System Sensor (AMSR-E) and Soil Moisture and Ocean Salinity (SMOS) passive microwave radiometers that were lunched on 2002 and 2009 respectively along with the upcoming Soil Moisture Active-Passive (SMAP) satellite that was planned to be lunched in the time frame of 2014-2015 make remote sensing to be more useful in soil moisture estimation. However, the spatial resolutions of AMSR-E, SMOS and SMAP are 60 km, 40 km and 10 km respectively. These very low spatial resolutions can not show the temporal and spatial variability of soil moisture in field or small scales. So, using disaggregation methods is required to efficiently using the passive microwave derived soil moisture information in different scales. The low spatial resolutions of passive microwave satellites can be improved by using disaggregation methods. Random Cascade (RC) model (Over and Gupta, 1996) is used in this research to downscale the 40 km resolution of SMOS satellite. By using this statistical method, the SMOS soil moisture resolutions are improved to 20 km, 10 km, 5 km and 2.5 km, respectively. The data that were measured during Soil Moisture Active Passive Validation Experiment 2012 (SMAPVEX12) field campaign are used to do the experiments. Totally the ground data and SMOS images that were obtained during 13 different days from 7-June-2012 to 13-July-2012 are used. By comparison with ground soil moisture, it is observed that the SMOS soil moisture is underestimated for all the images and so bias amounts

  18. Ecological, psychological, and cognitive components of reading difficulties: testing the component model of reading in fourth graders across 38 countries.

    Science.gov (United States)

    Chiu, Ming Ming; McBride-Chang, Catherine; Lin, Dan

    2012-01-01

    The authors tested the component model of reading (CMR) among 186,725 fourth grade students from 38 countries (45 regions) on five continents by analyzing the 2006 Progress in International Reading Literacy Study data using measures of ecological (country, family, school, teacher), psychological, and cognitive components. More than 91% of the differences in student difficulty occurred at the country (61%) and classroom (30%) levels (ecological), with less than 9% at the student level (cognitive and psychological). All three components were negatively associated with reading difficulties: cognitive (student's early literacy skills), ecological (family characteristics [socioeconomic status, number of books at home, and attitudes about reading], school characteristics [school climate and resources]), and psychological (students' attitudes about reading, reading self-concept, and being a girl). These results extend the CMR by demonstrating the importance of multiple levels of factors for reading deficits across diverse cultures.

  19. Random cascade driven rainfall disaggregation for urban hydrology: An evaluation of six models and a new generator

    Science.gov (United States)

    Licznar, Paweł; Łomotowski, Janusz; Rupp, David E.

    2011-03-01

    Six variations of multiplicative random cascade models for generating fine-resolution (i.e., 5-minute interval) rainfall time series were evaluated for rainfall in Wroclaw, Poland. Of these variations, one included a new beta-normal generator for a microcanonical cascade. This newly proposed model successfully reproduces the statistical behavior of local 5-minute rainfalls, in terms of intermittency as well as variability. In contrast, both the canonical cascade models with either constant or time-scaled parameters and a microcanonical cascade model with a beta generator substantially underestimate 5-minute maximum rainfall intensities. The canonical models also fail to properly reproduce the intermittency of the rainfall process across a range of timescales. New observations are also made concerning the histograms of the breakdown coefficients (BDC). The tendency of the BDC histograms to have values exactly equal to 0.5 is identified and explained by the quality of pluviograph records. Moreover, the hierarchical evolution of BDC histograms from beta-like for long time steps to beta-normal histograms for short time steps is observed for the first time. The potential advantage is shown of synthetic high resolution rainfall time series generated by the revised microcanonical model for use in hydrology, especially hydrodynamic modelling of urban drainage networks.

  20. Developmental, Component-Based Model of Reading Fluency: An Investigation of Predictors of Word-Reading Fluency, Text-Reading Fluency, and Reading Comprehension

    Science.gov (United States)

    Kim, Young-Suk Grace

    2015-01-01

    The primary goal was to expand our understanding of text-reading fluency (efficiency or automaticity): how its relation to other constructs (e.g., word-reading fluency, reading comprehension) changes over time and how it is different from word-reading fluency and reading comprehension. The study examined (a) developmentally changing relations…

  1. Developmental, Component-Based Model of Reading Fluency: An Investigation of Predictors of Word-Reading Fluency, Text-Reading Fluency, and Reading Comprehension

    Science.gov (United States)

    Kim, Young-Suk Grace

    2015-01-01

    The primary goal was to expand our understanding of text-reading fluency (efficiency or automaticity): how its relation to other constructs (e.g., word-reading fluency, reading comprehension) changes over time and how it is different from word-reading fluency and reading comprehension. The study examined (a) developmentally changing relations…

  2. Wavelet-based cascade model for intermittent structure in terrestrial environments

    CERN Document Server

    Wilson, D Keith; Vecherin, Sergey N

    2013-01-01

    A wavelet-like model for distributions of objects in natural and man-made terrestrial environments is developed. The model is constructed in a self-similar fashion, with the sizes, amplitudes, and numbers of objects occurring at a constant ratios between parent and offspring objects. The objects are randomly distributed in space according to a Poisson process. Fractal supports and a cascade model are used to organize objects intermittently in space. In its basic form, the model is for continuously varying random fields, although a level-cut is introduced to model two-phase random media. The report begins with a description of relevant concepts from fractal theory, and then progresses through static (time-invariant), steady-state, and non-steady models. The results can be applied to such diverse phenomena as turbulence, geologic distributions, urban buildings, vegetation, and arctic ice floes. The model can be used as a basis for synthesizing realistic terrestrial scenes, and for predicting the performance of ...

  3. Global robust output regulation control for cascaded nonlinear systems using the internal model principle

    Science.gov (United States)

    Yu, Jiang-Bo; Zhao, Yan; Wu, Yu-Qiang

    2014-04-01

    This article considers the global robust output regulation problem via output feedback for a class of cascaded nonlinear systems with input-to-state stable inverse dynamics. The system uncertainties depend not only on the measured output but also all the unmeasurable states. By introducing an internal model, the output regulation problem is converted into a stabilisation problem for an appropriately augmented system. The designed dynamic controller could achieve the global asymptotic tracking control for a class of time-varying reference signals for the system output while keeping all other closed-loop signals bounded. It is of interest to note that the developed control approach can be applied to the speed tracking control of the fan speed control system. The simulation results demonstrate its effectiveness.

  4. A probabilistic sediment cascade model of sediment transfer through a mountain basin

    Science.gov (United States)

    Bennett, G. L.; Molnar, P.; McArdell, B. W.; Lane, S. N.; Burlando, P.

    2013-12-01

    Mountain basin sediment discharge poses a significant hazard to the downstream population, particularly in the form of debris flows. The importance and sensitivity of snow and ice melt processes in mountain basins along with their rapid rainfall-runoff response makes mountain basin sediment discharge particularly responsive to climate change. It is important to understand and model sediment transfer through mountain basins to be able to predict sediment discharge under a changing climate. We developed a probabilistic sediment cascade model, SedCas, to simulate sediment transfer in a mountain basin (Illgraben, Switzerland) where sediment is produced by hillslope landslides and exported out of the basin by debris flows and floods. We present the model setup, the calibration of the model for the period 2000 - 2009 and the application of SedCas to model sediment discharge in the Illgraben over the 19th and 20th centuries. SedCas conceptualizes the fluvial system as a spatially lumped cascade of connected reservoirs representing hillslope and channel storages where sediment goes through multiple cycles of storage and remobilization by surface runoff. Sediment input is drawn from a probability distribution of slope failures produced for the basin from a time series of DEMs and the model is driven by observed climate. The model includes all relevant hydrological processes that lead to runoff in an Alpine basin, such as snow cover accumulation, snowmelt, evapotranspiration, and soil water storage. Although the processes of sediment transfer and debris flow generation are described in a simplified manner, SedCas produces highly complex sediment discharge behavior which is driven by the availability of sediment and antecedent moisture (system memory) as well as triggering potential (climate). The model reproduces the first order properties of observed debris flows over the period 2000-2009 including their probability distribution, seasonal timing and probability of

  5. A Novel Study: A Situation Model Analysis of Reading Times

    Science.gov (United States)

    McNerney, M. Windy; Goodwin, Kerri A.; Radvansky, Gabriel A.

    2011-01-01

    One of the basic findings on situation models and language comprehension is that reading times are affected by the changing event structure in a text. However, many studies have traditionally used multiple, relatively short texts, in which there is little event consistency across the texts. It is unclear to what extent such changes will be…

  6. The performance of a new Geant4 Bertini intra-nuclear cascade model in high throughput computing (HTC) cluster architecture

    Energy Technology Data Exchange (ETDEWEB)

    Aatos, Heikkinen; Andi, Hektor; Veikko, Karimaki; Tomas, Linden [Helsinki Univ., Institute of Physics (Finland)

    2003-07-01

    We study the performance of a new Bertini intra-nuclear cascade model implemented in the general detector simulation tool-kit Geant4 with a High Throughput Computing (HTC) cluster architecture. A 60 node Pentium III open-Mosix cluster is used with the Mosix kernel performing automatic process load-balancing across several CPUs. The Mosix cluster consists of several computer classes equipped with Windows NT workstations that automatically boot, daily and become nodes of the Mosix cluster. The models included in our study are a Bertini intra-nuclear cascade model with excitons, consisting of a pre-equilibrium model, a nucleus explosion model, a fission model and an evaporation model. The speed and accuracy obtained for these models is presented. (authors)

  7. The performance of a new Geant4 Bertini intra-nuclear cascade model in high throughput computing (HTC) cluster architecture

    Energy Technology Data Exchange (ETDEWEB)

    Aatos, Heikkinen; Andi, Hektor; Veikko, Karimaki; Tomas, Linden [Helsinki Univ., Institute of Physics (Finland)

    2003-07-01

    We study the performance of a new Bertini intra-nuclear cascade model implemented in the general detector simulation tool-kit Geant4 with a High Throughput Computing (HTC) cluster architecture. A 60 node Pentium III open-Mosix cluster is used with the Mosix kernel performing automatic process load-balancing across several CPUs. The Mosix cluster consists of several computer classes equipped with Windows NT workstations that automatically boot, daily and become nodes of the Mosix cluster. The models included in our study are a Bertini intra-nuclear cascade model with excitons, consisting of a pre-equilibrium model, a nucleus explosion model, a fission model and an evaporation model. The speed and accuracy obtained for these models is presented. (authors)

  8. A test of the multiple connections model of reading acquisition.

    Science.gov (United States)

    Berninger, V W; Chen, A C; Abbott, R D

    1988-10-01

    Within the framework of Society of Mind Theory (Minsky, 1986), learning to read is conceptualized as a process of creating new communication links or neural connections between an existing visual society and an existing linguistic society. Four visual-linguistic connections may become functional: letter-phonemic code, whole word-semantic code, whole word-name code, letter sequence-aural syllabic code. The hypothesis was tested that more than one of these visual-linguistic connections must be taken into account in predicting reading achievement. Results showed that the combination of the composite letter-phoneme variable and the composite whole word-semantic code variable accounted for significantly more variance in oral reading than did either single variable at the end of the first grade. Groups with large absolute discrepancy (1 or more standard scores) or small absolute discrepancy (1/3 standard score or less) on corresponding visual and linguistic skills differed significantly in both oral (whole word-semantic code composite) and silent reading (whole word-semantic code and letter sequence-aural syllabic code composites). There was a relationship between the number of large discrepancies and reading achievement. Results are discussed in reference to neuropsychological models of connectionism (Rumelhart & McClelland, 1986) and working brain systems (Luria, 1973).

  9. Transport-reaction model for defect and carrier behavior within displacement cascades in gallium arsenide

    Energy Technology Data Exchange (ETDEWEB)

    Wampler, William R.; Myers, Samuel Maxwell,

    2014-02-01

    A model is presented for recombination of charge carriers at displacement damage in gallium arsenide, which includes clustering of the defects in atomic displacement cascades produced by neutron or ion irradiation. The carrier recombination model is based on an atomistic description of capture and emission of carriers by the defects with time evolution resulting from the migration and reaction of the defects. The physics and equations on which the model is based are presented, along with details of the numerical methods used for their solution. The model uses a continuum description of diffusion, field-drift and reaction of carriers and defects within a representative spherically symmetric cluster. The initial radial defect profiles within the cluster were chosen through pair-correlation-function analysis of the spatial distribution of defects obtained from the binary-collision code MARLOWE, using recoil energies for fission neutrons. Charging of the defects can produce high electric fields within the cluster which may influence transport and reaction of carriers and defects, and which may enhance carrier recombination through band-to-trap tunneling. Properties of the defects are discussed and values for their parameters are given, many of which were obtained from density functional theory. The model provides a basis for predicting the transient response of III-V heterojunction bipolar transistors to pulsed neutron irradiation.

  10. A two-stage cascade model of BOLD responses in human visual cortex.

    Directory of Open Access Journals (Sweden)

    Kendrick N Kay

    Full Text Available Visual neuroscientists have discovered fundamental properties of neural representation through careful analysis of responses to controlled stimuli. Typically, different properties are studied and modeled separately. To integrate our knowledge, it is necessary to build general models that begin with an input image and predict responses to a wide range of stimuli. In this study, we develop a model that accepts an arbitrary band-pass grayscale image as input and predicts blood oxygenation level dependent (BOLD responses in early visual cortex as output. The model has a cascade architecture, consisting of two stages of linear and nonlinear operations. The first stage involves well-established computations-local oriented filters and divisive normalization-whereas the second stage involves novel computations-compressive spatial summation (a form of normalization and a variance-like nonlinearity that generates selectivity for second-order contrast. The parameters of the model, which are estimated from BOLD data, vary systematically across visual field maps: compared to primary visual cortex, extrastriate maps generally have larger receptive field size, stronger levels of normalization, and increased selectivity for second-order contrast. Our results provide insight into how stimuli are encoded and transformed in successive stages of visual processing.

  11. Hyperpolarization-Activated Current Induces Period-Doubling Cascades and Chaos in a Cold Thermoreceptor Model

    Science.gov (United States)

    Xu, Kesheng; Maidana, Jean P.; Caviedes, Mauricio; Quero, Daniel; Aguirre, Pablo; Orio, Patricio

    2017-01-01

    In this article, we describe and analyze the chaotic behavior of a conductance-based neuronal bursting model. This is a model with a reduced number of variables, yet it retains biophysical plausibility. Inspired by the activity of cold thermoreceptors, the model contains a persistent Sodium current, a Calcium-activated Potassium current and a hyperpolarization-activated current (Ih) that drive a slow subthreshold oscillation. Driven by this oscillation, a fast subsystem (fast Sodium and Potassium currents) fires action potentials in a periodic fashion. Depending on the parameters, this model can generate a variety of firing patterns that includes bursting, regular tonic and polymodal firing. Here we show that the transitions between different firing patterns are often accompanied by a range of chaotic firing, as suggested by an irregular, non-periodic firing pattern. To confirm this, we measure the maximum Lyapunov exponent of the voltage trajectories, and the Lyapunov exponent and Lempel-Ziv's complexity of the ISI time series. The four-variable slow system (without spiking) also generates chaotic behavior, and bifurcation analysis shows that this is often originated by period doubling cascades. Either with or without spikes, chaos is no longer generated when the Ih is removed from the system. As the model is biologically plausible with biophysically meaningful parameters, we propose it as a useful tool to understand chaotic dynamics in neurons. PMID:28344550

  12. An Enhanced Analytical Target Cascading and Kriging Model Combined Approach for Multidisciplinary Design Optimization

    Directory of Open Access Journals (Sweden)

    Ping Jiang

    2015-01-01

    Full Text Available Multidisciplinary design optimization (MDO has been applied widely in the design of complex engineering systems. To ease MDO problems, analytical target cascading (ATC organizes MDO process into multilevels according to the components of engineering systems, which provides a promising way to deal with MDO problems. ATC adopts a coordination strategy to coordinate the couplings between two adjacent levels in the design optimization process; however, existing coordination strategies in ATC face the obstacles of complicated coordination process and heavy computation cost. In order to conquer this problem, a quadratic exterior penalty function (QEPF based ATC (QEPF-ATC approach is proposed, where QEPF is adopted as the coordination strategy. Moreover, approximate models are adopted widely to replace the expensive simulation models in MDO; a QEPF-ATC and Kriging model combined approach is further proposed to deal with MDO problems, owing to the comprehensive performance, high approximation accuracy, and robustness of Kriging model. Finally, the geometric programming and reducer design cases are given to validate the applicability and efficiency of the proposed approach.

  13. PACIAE 2.1: An Updated Issue of Parton and Hadron Cascade Model PACIAE 2.0

    Institute of Scientific and Technical Information of China (English)

    SA; Ben-hao; ZHOU; Dai-mei; YAN; Yu-liang; DONG; Bao-guo; CAI; Xu

    2013-01-01

    We have updated the parton and hadron cascade model PACIAE 2.0 to the new issue of PACIAE 2.1.The PACIAE model is based on PYTHIA.In the PYTHIA model,once the generated particle or parton transverse momentum pT is randomly sampled,the px and py components are originally put on the circle with radius pT randomly.Now,it is put

  14. Influence maximization in social networks under an independent cascade-based model

    Science.gov (United States)

    Wang, Qiyao; Jin, Yuehui; Lin, Zhen; Cheng, Shiduan; Yang, Tan

    2016-02-01

    The rapid growth of online social networks is important for viral marketing. Influence maximization refers to the process of finding influential users who make the most of information or product adoption. An independent cascade-based model for influence maximization, called IMIC-OC, was proposed to calculate positive influence. We assumed that influential users spread positive opinions. At the beginning, users held positive or negative opinions as their initial opinions. When more users became involved in the discussions, users balanced their own opinions and those of their neighbors. The number of users who did not change positive opinions was used to determine positive influence. Corresponding influential users who had maximum positive influence were then obtained. Experiments were conducted on three real networks, namely, Facebook, HEP-PH and Epinions, to calculate maximum positive influence based on the IMIC-OC model and two other baseline methods. The proposed model resulted in larger positive influence, thus indicating better performance compared with the baseline methods.

  15. Transient dynamics and food-web complexity in the Lotka-Volterra cascade model.

    Science.gov (United States)

    Chen, X.; Cohen, J. E.

    2001-01-01

    How does the long-term behaviour near equilibrium of model food webs correlate with their short-term transient dynamics? Here, simulations of the Lotka -Volterra cascade model of food webs provide the first evidence to answer this question. Transient behaviour is measured by resilience, reactivity, the maximum amplification of a perturbation and the time at which the maximum amplification occurs. Model food webs with a higher probability of local asymptotic stability may be less resilient and may have a larger transient growth of perturbations. Given a fixed connectance, the sizes and durations of transient responses to perturbations increase with the number of species. Given a fixed number of species, as connectance increases, the sizes and durations of transient responses to perturbations may increase or decrease depending on the type of link that is varied. Reactivity is more sensitive to changes in the number of donor-controlled links than to changes in the number of recipient-controlled links, while resilience is more sensitive to changes in the number of recipient-controlled links than to changes in the number of donor-controlled links. Transient behaviour is likely to be one of the important factors affecting the persistence of ecological communities. PMID:11345334

  16. Market disruption, cascading effects, and economic recovery:a life-cycle hypothesis model.

    Energy Technology Data Exchange (ETDEWEB)

    Sprigg, James A.

    2004-11-01

    This paper builds upon previous work [Sprigg and Ehlen, 2004] by introducing a bond market into a model of production and employment. The previous paper described an economy in which households choose whether to enter the labor and product markets based on wages and prices. Firms experiment with prices and employment levels to maximize their profits. We developed agent-based simulations using Aspen, a powerful economic modeling tool developed at Sandia, to demonstrate that multiple-firm economies converge toward the competitive equilibria typified by lower prices and higher output and employment, but also suffer from market noise stemming from consumer churn. In this paper we introduce a bond market as a mechanism for household savings. We simulate an economy of continuous overlapping generations in which each household grows older in the course of the simulation and continually revises its target level of savings according to a life-cycle hypothesis. Households can seek employment, earn income, purchase goods, and contribute to savings until they reach the mandatory retirement age; upon retirement households must draw from savings in order to purchase goods. This paper demonstrates the simultaneous convergence of product, labor, and savings markets to their calculated equilibria, and simulates how a disruption to a productive sector will create cascading effects in all markets. Subsequent work will use similar models to simulate how disruptions, such as terrorist attacks, would interplay with consumer confidence to affect financial markets and the broader economy.

  17. Transient dynamics and food-web complexity in the Lotka-Volterra cascade model.

    Science.gov (United States)

    Chen, X; Cohen, J E

    2001-04-22

    How does the long-term behaviour near equilibrium of model food webs correlate with their short-term transient dynamics? Here, simulations of the Lotka -Volterra cascade model of food webs provide the first evidence to answer this question. Transient behaviour is measured by resilience, reactivity, the maximum amplification of a perturbation and the time at which the maximum amplification occurs. Model food webs with a higher probability of local asymptotic stability may be less resilient and may have a larger transient growth of perturbations. Given a fixed connectance, the sizes and durations of transient responses to perturbations increase with the number of species. Given a fixed number of species, as connectance increases, the sizes and durations of transient responses to perturbations may increase or decrease depending on the type of link that is varied. Reactivity is more sensitive to changes in the number of donor-controlled links than to changes in the number of recipient-controlled links, while resilience is more sensitive to changes in the number of recipient-controlled links than to changes in the number of donor-controlled links. Transient behaviour is likely to be one of the important factors affecting the persistence of ecological communities.

  18. Scaffolding in L2 Reading: How Repetition and an Auditory Model Help Readers

    Science.gov (United States)

    Taguchi, Etsuo; Gorsuch, Greta; Lems, Kristin; Rosszell, Rory

    2016-01-01

    Reading fluency research and practice have recently undergone some changes. While past studies and interventions focused on reading speed as their main goal, now more emphasis is being placed on exploring the role prosody plays in reading, and how listening to an audio model of a text while reading may act as a form of scaffolding, or aid, to…

  19. Improved Dynamic Modeling of the Cascade Distillation Subsystem and Analysis of Factors Affecting Its Performance

    Science.gov (United States)

    Perry, Bruce A.; Anderson, Molly S.

    2015-01-01

    The Cascade Distillation Subsystem (CDS) is a rotary multistage distiller being developed to serve as the primary processor for wastewater recovery during long-duration space missions. The CDS could be integrated with a system similar to the International Space Station Water Processor Assembly to form a complete water recovery system for future missions. A preliminary chemical process simulation was previously developed using Aspen Custom Modeler® (ACM), but it could not simulate thermal startup and lacked detailed analysis of several key internal processes, including heat transfer between stages. This paper describes modifications to the ACM simulation of the CDS that improve its capabilities and the accuracy of its predictions. Notably, the modified version can be used to model thermal startup and predicts the total energy consumption of the CDS. The simulation has been validated for both NaC1 solution and pretreated urine feeds and no longer requires retuning when operating parameters change. The simulation was also used to predict how internal processes and operating conditions of the CDS affect its performance. In particular, it is shown that the coefficient of performance of the thermoelectric heat pump used to provide heating and cooling for the CDS is the largest factor in determining CDS efficiency. Intrastage heat transfer affects CDS performance indirectly through effects on the coefficient of performance.

  20. Parallelizing Backpropagation Neural Network Using MapReduce and Cascading Model.

    Science.gov (United States)

    Liu, Yang; Jing, Weizhe; Xu, Lixiong

    2016-01-01

    Artificial Neural Network (ANN) is a widely used algorithm in pattern recognition, classification, and prediction fields. Among a number of neural networks, backpropagation neural network (BPNN) has become the most famous one due to its remarkable function approximation ability. However, a standard BPNN frequently employs a large number of sum and sigmoid calculations, which may result in low efficiency in dealing with large volume of data. Therefore to parallelize BPNN using distributed computing technologies is an effective way to improve the algorithm performance in terms of efficiency. However, traditional parallelization may lead to accuracy loss. Although several complements have been done, it is still difficult to find out a compromise between efficiency and precision. This paper presents a parallelized BPNN based on MapReduce computing model which supplies advanced features including fault tolerance, data replication, and load balancing. And also to improve the algorithm performance in terms of precision, this paper creates a cascading model based classification approach, which helps to refine the classification results. The experimental results indicate that the presented parallelized BPNN is able to offer high efficiency whilst maintaining excellent precision in enabling large-scale machine learning.

  1. Parallelizing Backpropagation Neural Network Using MapReduce and Cascading Model

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2016-01-01

    Full Text Available Artificial Neural Network (ANN is a widely used algorithm in pattern recognition, classification, and prediction fields. Among a number of neural networks, backpropagation neural network (BPNN has become the most famous one due to its remarkable function approximation ability. However, a standard BPNN frequently employs a large number of sum and sigmoid calculations, which may result in low efficiency in dealing with large volume of data. Therefore to parallelize BPNN using distributed computing technologies is an effective way to improve the algorithm performance in terms of efficiency. However, traditional parallelization may lead to accuracy loss. Although several complements have been done, it is still difficult to find out a compromise between efficiency and precision. This paper presents a parallelized BPNN based on MapReduce computing model which supplies advanced features including fault tolerance, data replication, and load balancing. And also to improve the algorithm performance in terms of precision, this paper creates a cascading model based classification approach, which helps to refine the classification results. The experimental results indicate that the presented parallelized BPNN is able to offer high efficiency whilst maintaining excellent precision in enabling large-scale machine learning.

  2. Extended density-matrix model applied to silicon-based terahertz quantum cascade lasers

    Science.gov (United States)

    Dinh, T. V.; Valavanis, A.; Lever, L. J. M.; Ikonić, Z.; Kelsall, R. W.

    2012-06-01

    Silicon-based terahertz quantum cascade lasers (QCLs) offer potential advantages over existing III-V devices. Although coherent electron transport effects are known to be important in QCLs, they have never been considered in Si-based device designs. We describe a density-matrix transport model that is designed to be more general than those in previous studies and to require less a priori knowledge of electronic band structure, allowing its use in semiautomated design procedures. The basis of the model includes all states involved in interperiod transport, and our steady-state solution extends beyond the rotating-wave approximation by including dc and counterpropagating terms. We simulate the potential performance of bound-to-continuum Ge/SiGe QCLs and find that devices with 4-5-nm-thick barriers give the highest simulated optical gain. We also examine the effects of interdiffusion between Ge and SiGe layers; we show that if it is taken into account in the design, interdiffusion lengths of up to 1.5 nm do not significantly affect the simulated device performance.

  3. Predator prey oscillations in a simple cascade model of drift wave turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Berionni, V.; Guercan, Oe. D. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex (France)

    2011-11-15

    A reduced three shell limit of a simple cascade model of drift wave turbulence, which emphasizes nonlocal interactions with a large scale mode, is considered. It is shown to describe both the well known predator prey dynamics between the drift waves and zonal flows and to reduce to the standard three wave interaction equations. Here, this model is considered as a dynamical system whose characteristics are investigated. The analytical solutions for the purely nonlinear limit are given in terms of the Jacobi elliptic functions. An approximate analytical solution involving Jacobi elliptic functions and exponential growth is computed using scale separation for the case of unstable solutions that are observed when the energy injection rate is high. The fixed points of the system are determined, and the behavior around these fixed points is studied. The system is shown to display periodic solutions corresponding to limit cycle oscillations, apparently chaotic phase space orbits, as well as unstable solutions that grow slowly while oscillating rapidly. The period doubling route to transition to chaos is examined.

  4. Modeling strategic competition in hydro-thermal electricity generation markets with cascaded reservoir-hydroelectric generation plants

    Science.gov (United States)

    Uluca, Basak

    This dissertation aims to achieve two goals. The first is to model the strategic interactions of firms that own cascaded reservoir-hydro plants in oligopolistic and mixed oligopolistic hydrothermal electricity generation markets. Although competition in thermal generation has been extensively modeled since the beginning of deregulation, the literature on competition in hydro generation is still limited; in particular, equilibrium models of oligopoly that study the competitive behavior of firms that own reservoir-hydro plants along the same river in hydrothermal electricity generation markets are still under development. In competitive markets, when the reservoirs are located along the same river, the water released from an upstream reservoir for electricity generation becomes input to the immediate downstream reservoir, which may be owned by a competitor, for current or future use. To capture the strategic interactions among firms with cascaded reservoir-hydro plants, the Upstream-Conjecture approach is proposed. Under the Upstream-Conjecture approach, a firm with an upstream reservoir-hydro plant assumes that firms with downstream reservoir-hydro plants will respond to changes in the upstream firm's water release by adjusting their water release by the same amount. The results of the Upstream Conjecture experiments indicate that firms that own upstream reservoirs in a cascade may have incentive to withhold or limit hydro generation, forcing a reduction in the utilization of the downstream hydro generation plants that are owned by competitors. Introducing competition to hydroelectricity generation markets is challenging and ownership allocation of the previously state-owned cascaded reservoir-hydro plants through privatization can have significant impact on the competitiveness of the generation market. The second goal of the dissertation is to extract empirical guidance about best policy choices for the ownership of the state-owned generation plants, including the

  5. Expanding the Four Resources Model: Reading Visual and Multi-Modal Texts

    Science.gov (United States)

    Serafini, Frank

    2012-01-01

    Freebody and Luke proffered an expanded conceptualization of the resources readers utilize when reading and the roles readers adopt during the act of reading. The four resources model, and its associated four roles of the reader, expanded the definition of reading from a simple model of decoding printed texts to a model of constructing meaning and…

  6. $\\gamma$-ray and X-ray luminosities from spin-powered pulsars in the full polar cap cascade model

    CERN Document Server

    Zhang, B; Zhang, Bing; Harding, Alice K.

    2000-01-01

    We modify the conventional curvature radiation (inverse Compton scattering) + synchrotron radiation polar cap cascade model by including the inverse Compton scattering of the higher generation pairs. Within the framework of the space-charge-limited-flow acceleration model with frame-dragging proposed by Harding & Muslimov (1998), such a full polar cap cascade scenario can well reproduce the $L_\\gamma \\propto (L_{\\rm sd})^{1/2}$ and the $L_x \\sim 10^{-3} L_{\\rm sd}$ dependences observed from the known spin-powered pulsars. According to this model, the ``pulsed'' soft ROSAT-band X-rays from most of the millisecond pulsars might be of thermal origin, if there are no strong multipole magnetic components near their surfaces.

  7. Cascading water underneath Wilkes Land, East Antarctic Ice Sheet, observed using altimetry and digital elevation models

    Directory of Open Access Journals (Sweden)

    T. Flament

    2013-03-01

    Full Text Available We describe a major subglacial lake drainage close to the ice divide in Wilkes Land, East Antarctica, and the subsequent cascading of water underneath the ice sheet toward the coast. To analyze the event, we combined altimetry data from several sources and bedrock data. We estimated the total volume of water that drained from Lake CookE2 by differencing digital elevation models (DEM derived from ASTER and SPOT5 stereo-imagery. With 5.2 ± 0.5 km3, this is the largest single subglacial drainage event reported so far in Antarctica. Elevation differences between ICESat laser altimetry and the SPOT5 DEM indicate that the discharge lasted approximately 2 yr. A 13-m uplift of the surface, corresponding to a refilling of about 0.64 ± 0.32 km3, was observed between the end of the discharge in October 2008 and February 2012. Using Envisat radar altimetry, with its high 35-day temporal resolution, we monitored the subsequent filling and drainage of connected subglacial lakes located downstream. In particular, a transient temporal signal can be detected within the theoretical 500-km long flow paths computed with the BEDMAP2 data set. The volume of water traveling in this wave is in agreement with the volume that drained from Lake CookE2. These observations contribute to a better understanding of the water transport beneath the East Antarctic ice sheet.

  8. Modeling of dilute nitride cascaded quantum well solar cells for high efficiency photovoltaics

    Science.gov (United States)

    Vijaya, G.; Alemu, A.; Freundlich, A.

    2013-03-01

    III-V Dilute Nitride multi-quantum well structures are currently promising candidates to achieve 1 sun efficiencies of cell in a 4 junction configuration could yield 1 sun efficiencies greater than 40%. However for a conventional deep well design the characteristic carrier escape times could exceed that of radiative recombination hence limiting the current output of the cell, as has been indicated by prior experiments. In order to increase the current extraction here we evaluate the performance of a cascaded quantum well design whereby a thermally assisted resonant tunneling process is used to accelerate the carrier escape process (efficiency. The quantum efficiency of a p-i-n subcell where a periodic sequence of quantum wells with well and barrier thicknesses adjusted for the sequential extraction operation is calculated using a 2D drift diffusion model and taking into account absorption properties of resulting MQWs. The calculation also accounts for the E-field induced modifications of absorption properties and quantization in quantum wells. The results are then accounted for to calculate efficiencies for the proposed 4 junction design, and indicate potential for reaching efficiencies in excess of this structure is above 42% (1 sun) and above 50% (500 sun) AM1.5.

  9. Improved Dynamic Modeling of the Cascade Distillation Subsystem and Integration with Models of Other Water Recovery Subsystems

    Science.gov (United States)

    Perry, Bruce; Anderson, Molly

    2015-01-01

    The Cascade Distillation Subsystem (CDS) is a rotary multistage distiller being developed to serve as the primary processor for wastewater recovery during long-duration space missions. The CDS could be integrated with a system similar to the International Space Station (ISS) Water Processor Assembly (WPA) to form a complete Water Recovery System (WRS) for future missions. Independent chemical process simulations with varying levels of detail have previously been developed using Aspen Custom Modeler (ACM) to aid in the analysis of the CDS and several WPA components. The existing CDS simulation could not model behavior during thermal startup and lacked detailed analysis of several key internal processes, including heat transfer between stages. The first part of this paper describes modifications to the ACM model of the CDS that improve its capabilities and the accuracy of its predictions. Notably, the modified version of the model can accurately predict behavior during thermal startup for both NaCl solution and pretreated urine feeds. The model is used to predict how changing operating parameters and design features of the CDS affects its performance, and conclusions from these predictions are discussed. The second part of this paper describes the integration of the modified CDS model and the existing WPA component models into a single WRS model. The integrated model is used to demonstrate the effects that changes to one component can have on the dynamic behavior of the system as a whole.

  10. Downscale cascades in tracer transport test cases: an intercomparison of the dynamical cores in the Community Atmosphere Model CAM5

    Directory of Open Access Journals (Sweden)

    J. Kent

    2012-07-01

    Full Text Available The accurate modelling of cascades to unresolved scales is an important part of the tracer transport component of dynamical cores of weather and climate models. This paper aims to investigate the ability of the advection schemes in the National Center for Atmospheric Research's Community Atmosphere Model version 5 (CAM5 to model this cascade. In order to quantify the effects of the different advection schemes in CAM5, four two-dimensional tracer transport test cases are presented. Three of the tests stretch the tracer below the scale of coarse resolution grids to ensure the downscale cascade of tracer variance. These results are compared with a high resolution reference solution, which is simulated on a resolution fine enough to resolve the tracer during the test. The fourth test has two separate flow cells, and is designed so that any tracer in the Western Hemisphere should not pass into the Eastern Hemisphere. This is to test whether the diffusion in transport schemes, often in the form of explicit hyper-diffusion terms or implicit through monotonic limiters, contains unphysical mixing.

    An intercomparison of three of the dynamical cores of the National Center for Atmospheric Research's Community Atmosphere Model version 5 is performed. The results show that the finite-volume (CAM-FV and spectral element (CAM-SE dynamical cores model the downscale cascade of tracer variance better than the semi-Lagrangian transport scheme of the Eulerian spectral transform core (CAM-EUL. Each scheme tested produces unphysical mass in the Eastern Hemisphere of the separate cells test.

  11. Downscale cascades in tracer transport test cases: an intercomparison of the dynamical cores in the Community Atmosphere Model CAM5

    Directory of Open Access Journals (Sweden)

    J. Kent

    2012-12-01

    Full Text Available The accurate modeling of cascades to unresolved scales is an important part of the tracer transport component of dynamical cores of weather and climate models. This paper aims to investigate the ability of the advection schemes in the National Center for Atmospheric Research's Community Atmosphere Model version 5 (CAM5 to model this cascade. In order to quantify the effects of the different advection schemes in CAM5, four two-dimensional tracer transport test cases are presented. Three of the tests stretch the tracer below the scale of coarse resolution grids to ensure the downscale cascade of tracer variance. These results are compared with a high resolution reference solution, which is simulated on a resolution fine enough to resolve the tracer during the test. The fourth test has two separate flow cells, and is designed so that any tracer in the western hemisphere should not pass into the eastern hemisphere. This is to test whether the diffusion in transport schemes, often in the form of explicit hyper-diffusion terms or implicit through monotonic limiters, contains unphysical mixing.

    An intercomparison of three of the dynamical cores of the National Center for Atmospheric Research's Community Atmosphere Model version 5 is performed. The results show that the finite-volume (CAM-FV and spectral element (CAM-SE dynamical cores model the downscale cascade of tracer variance better than the semi-Lagrangian transport scheme of the Eulerian spectral transform core (CAM-EUL. Each scheme tested produces unphysical mass in the eastern hemisphere of the separate cells test.

  12. The construction of visual-spatial situation models in children's reading and their relation to reading comprehension.

    Science.gov (United States)

    Barnes, Marcia A; Raghubar, Kimberly P; Faulkner, Heather; Denton, Carolyn A

    2014-03-01

    Readers construct mental models of situations described by text to comprehend what they read, updating these situation models based on explicitly described and inferred information about causal, temporal, and spatial relations. Fluent adult readers update their situation models while reading narrative text based in part on spatial location information that is consistent with the perspective of the protagonist. The current study investigated whether children update spatial situation models in a similar way, whether there are age-related changes in children's formation of spatial situation models during reading, and whether measures of the ability to construct and update spatial situation models are predictive of reading comprehension. Typically developing children from 9 to 16 years of age (N=81) were familiarized with a physical model of a marketplace. Then the model was covered, and children read stories that described the movement of a protagonist through the marketplace and were administered items requiring memory for both explicitly stated and inferred information about the character's movements. Accuracy of responses and response times were evaluated. Results indicated that (a) location and object information during reading appeared to be activated and updated not simply from explicit text-based information but from a mental model of the real-world situation described by the text; (b) this pattern showed no age-related differences; and (c) the ability to update the situation model of the text based on inferred information, but not explicitly stated information, was uniquely predictive of reading comprehension after accounting for word decoding. Copyright © 2013 Elsevier Inc. All rights reserved.

  13. One-parameter cascade model of multiple hadrons production in inelastic hh-processes at high energies

    Energy Technology Data Exchange (ETDEWEB)

    Rusov, V.D. [Department of Theoretical and Experimental Nuclear Physics, Odessa National Polytechnic University, Shevchenko av. 1, Odessa 65044 (Ukraine)]. E-mail: siiis@te.net.ua; Sharf, I.V. [Department of Theoretical and Experimental Nuclear Physics, Odessa National Polytechnic University, Shevchenko av. 1, Odessa 65044 (Ukraine)

    2006-01-09

    The inhomogeneous cascade-stochastic model of multiple hadrons production in inelastic p-bar p- and pp-interactions at high energies is proposed. In this model inclusive rapidity distributions of secondary hadrons are used as input data. One-parameter cascade-stochastic multiplicity distribution, where adjustable parameter has sense of the height of Feynman plateau of inclusive rapidity distribution of secondary hadrons in one hadron shower, is obtained. It is shown that all known now experimental data concerning both multiplicity and rapidity distributions of secondary particles in inelastic hh-processes in energy range s=30-1800 GeV, and also the ratio of cumulant moments to factorial moments of the multiplicity distributions in energy range s=200-900 GeV are described with high accuracy by one-parameter cascade-stochastic model of multiple hadrons production. The explicit form of asymptotic of distributions as well-known Polyakov-Dokshitzer's scaling function for quark and gluon jets is obtained by fitting of prognosis multiplicity distributions at energies s=14-30 TeV. A simplified quantitative analysis is presented and the qualitative explanation of behavior features of forward-backward multiplicity correlations is given within the framework of proposed model.

  14. Improvements in quantum cascade laser performance through comprehensive modeling and experiments

    Science.gov (United States)

    Howard, Scott Sheridan

    Prior to the invention of the quantum cascade (QC) laser, many applications based on mid-infrared (mid-IR) laser absorption spectroscopy were not be explored. Development of the QC laser provided an inherently compact, semiconductor based, and tunable mid-IR source that could be used for laser absorption spectroscopy. Additionally, QC lasers can be designed to emit at a specific wavelength within a very wide wavelength range from between 3 and 30 mum and can be fabricated to operate single-mode to clearly scan mid-IR absorption "fingerprints" [1]. This allows lasers to be tailored to the exact wavelength of an absorption feature. Two examples of absorption spectroscopy experiments were carried out as part of this dissertation and described herein: C60 in space and dissolved gasses in living tissue. Although QC lasers allow for application development in the mid-IR, they are inefficient and heat dissipation is problematic. First generation QC lasers relied on either bulky cryogenic cooling systems for continuous wave operation or large, expensive pulse generators [2]. Later, advances in QC laser design, growth, and fabrication led to room-temperature continuous wave operation [3]. These advances promoted additional applications of QC lasers where cryogenic cooling was impossible or highly inconvenient. This dissertation presents comprehensive self-consistent models permitting the optimization of high operating temperature QC lasers. These models employ strategies counter to those used in designing low temperature devices and were used to design, fabricate, and demonstrate high-performance QC lasers. By self-consistently solving the temperature dependent threshold current density and heat equations, including temperature dependent thermal conductivities, phonon lifetimes, thermal "backfilling," thermionic emission, and energy level broadening, we calculated the effects of doping level, material choice, and waveguide layer thickness on the laser threshold performance

  15. Modeling regulatory cascades using Artificial Neural Networks: the case of transcriptional regulatory networks shaped during the yeast stress response.

    Science.gov (United States)

    Manioudaki, Maria E; Poirazi, Panayiota

    2013-01-01

    Over the last decade, numerous computational methods have been developed in order to infer and model biological networks. Transcriptional networks in particular have attracted significant attention due to their critical role in cell survival. The majority of network inference methods use genome-wide experimental data to search for modules of genes with coherent expression profiles and common regulators, often ignoring the multi-layer structure of transcriptional cascades. Modeling methodologies on the other hand assume a given network structure and vary significantly in their algorithmic approach, ranging from over-simplified representations (e.g., Boolean networks) to detailed -but computationally expensive-network simulations (e.g., with differential equations). In this work we use Artificial Neural Networks (ANNs) to model transcriptional regulatory cascades that emerge during the stress response in Saccharomyces cerevisiae and extend in three layers. We confine the structure of the ANNs to match the structure of the biological networks as determined by gene expression, DNA-protein interaction and experimental evidence provided in publicly available databases. Trained ANNs are able to predict the expression profile of 11 target genes across multiple experimental conditions with a correlation coefficient >0.7. When time-dependent interactions between upstream transcription factors (TFs) and their indirect targets are also included in the ANNs, accurate predictions are achieved for 30/34 target genes. Moreover, heterodimer formation is taken into account. We show that ANNs can be used to (1) accurately predict the expression of downstream genes in a 3-layer transcriptional cascade based on the expression of their indirect regulators and (2) infer the condition- and time-dependent activity of various TFs as well as during heterodimer formation. We show that a three-layer regulatory cascade whose structure is determined by co-expressed gene modules and their

  16. Functional model for gas sensing based on quantum cascade lasers; Funktionsmuster zur Gasdetektion auf Basis von Quantenkaskadenlasern

    Energy Technology Data Exchange (ETDEWEB)

    Steinbeck, T.; Rohr, J. [m.u.t. GmbH, Wedel (Germany)

    2005-06-01

    Quantum cascade lasers represent an almost ideal light source for infrared gas analysis. They allow sensitive and selective measurements in the mid-infrared. The detection of combustion gases for early fire detection represents an interesting field of application, where further technologic benefits are shown to advantage. The focus of this report is on the technical realization of a functional model and the electronic components. (orig.)

  17. The impact of the topology on cascading failures in a power grid model

    Science.gov (United States)

    Koç, Yakup; Warnier, Martijn; Mieghem, Piet Van; Kooij, Robert E.; Brazier, Frances M. T.

    2014-05-01

    Cascading failures are one of the main reasons for large scale blackouts in power transmission grids. Secure electrical power supply requires, together with careful operation, a robust design of the electrical power grid topology. Currently, the impact of the topology on grid robustness is mainly assessed by purely topological approaches, that fail to capture the essence of electric power flow. This paper proposes a metric, the effective graph resistance, to relate the topology of a power grid to its robustness against cascading failures by deliberate attacks, while also taking the fundamental characteristics of the electric power grid into account such as power flow allocation according to Kirchhoff laws. Experimental verification on synthetic power systems shows that the proposed metric reflects the grid robustness accurately. The proposed metric is used to optimize a grid topology for a higher level of robustness. To demonstrate its applicability, the metric is applied on the IEEE 118 bus power system to improve its robustness against cascading failures.

  18. Spontaneous Current-layer Fragmentation and Cascading Reconnection in Solar Flares. I. Model and Analysis

    Science.gov (United States)

    Bárta, Miroslav; Büchner, Jörg; Karlický, Marian; Skála, Jan

    2011-08-01

    Magnetic reconnection is commonly considered to be a mechanism of solar (eruptive) flares. A deeper study of this scenario reveals, however, a number of open issues. Among them is the fundamental question of how the magnetic energy is transferred from large, accumulation scales to plasma scales where its actual dissipation takes place. In order to investigate this transfer over a broad range of scales, we address this question by means of a high-resolution MHD simulation. The simulation results indicate that the magnetic-energy transfer to small scales is realized via a cascade of consecutively smaller and smaller flux ropes (plasmoids), analogous to the vortex-tube cascade in (incompressible) fluid dynamics. Both tearing and (driven) "fragmenting coalescence" processes are equally important for the consecutive fragmentation of the magnetic field (and associated current density) into smaller elements. At the later stages, a dynamic balance between tearing and coalescence processes reveals a steady (power-law) scaling typical of cascading processes. It is shown that cascading reconnection also addresses other open issues in solar-flare research, such as the duality between the regular large-scale picture of (eruptive) flares and the observed signatures of fragmented (chaotic) energy release, as well as the huge number of accelerated particles. Indeed, spontaneous current-layer fragmentation and the formation of multiple channelized dissipative/acceleration regions embedded in the current layer appear to be intrinsic to the cascading process. The multiple small-scale current sheets may also facilitate the acceleration of a large number of particles. The structure, distribution, and dynamics of the embedded potential acceleration regions in a current layer fragmented by cascading reconnection are studied and discussed.

  19. Modeling off-resonant nonlinear-optical cascading in mesoscopic thin films and guest-host molecular systems

    CERN Document Server

    Dawson, Nathan J; Crescimanno, Michael

    2013-01-01

    We develop a model for off-resonant microscopic cascading of scalar polarizabilities using a self-consistent field approach, and use it to study the effects of boundaries on mesoscopic systems of nonlinear polarizable atoms and molecules. We find that higher-ordered susceptibilities can be enhanced by increasing the surface-to-volume ratio through reducing the distance between boundaries perpendicular to the linear polarization. We also show lattice scaling effects on the effective nonlinear refractive indices for Gaussian beams, and illustrate finite size effects on dipole field distributions in films subject to long-wavelength propagating fields. We derive simplified expressions for the microscopic cascading of the nonlinear optical response in guest-host systems.

  20. Spectra of produced particles at CERN SPS heavy-ion collisions from a parton-cascade model

    CERN Document Server

    Srivastava, D K; Srivastava, Dinesh Kumar; Geiger, Klaus

    1998-01-01

    We evaluate the spectra of produced particles (pions, kaons, antiprotons) from partonic cascades which may develop in the wake of heavy-ion collisions at CERN SPS energies and which may hadronize by formation of clusters which decay into hadrons. Using the experimental data obtained by NA35 and NA44 collaborations for S+S and Pb+Pb collisions, we conclude that the Monte Carlo implementation of the recently developed parton-cascade/cluster-hadronization model provides a reasonable description of the distributions of the particles produced in such collisions. While the rapidity distribution of the mid-rapidity protons is described reasonably well, their transverse momentum distribution falls too rapidly compared to the experimental values, implying a significant effect of final state scattering among the produced hadrons neglected so far.

  1. Numerical modeling of energy-separation in cascaded Leontiev tubes with a central body

    Directory of Open Access Journals (Sweden)

    Makarov Maksim

    2017-01-01

    Full Text Available Designs of two- and three-cascaded Leontiev tubes are proposed in the paper. The results of numerical simulation of the energy separation in such tubes are presented. The efficiency parameters are determined in direct flows of helium-xenon coolant with low Prandtl number.

  2. Supercritical Airfoil Technology Program Wake Experiments and Modeling for Fore- and Aft-Loaded Compressor Cascades.

    Science.gov (United States)

    1980-09-01

    Miss Diane Rodimon for her programming skills and data reduction and to Mr. David Potash for the cascade construction and data acquisition. DDC TAB II...I were normalized by the wake half-width. The fit used in Reference 20 ( efl n2) is excellent for the far downstream traverses (i.e., X/BX > 0.057

  3. The Impact of the Topology on Cascading Failures in a Power Grid Model

    NARCIS (Netherlands)

    Koç, Y.; Warnier, M.; Van Mieghem, P.; Kooij, R.E.; Brazier, F.M.T.

    2014-01-01

    Cascading failures are one of the main reasons for large scale blackouts in power transmission grids. Secure electrical power supply requires, together with careful operation, a robust design of the electrical power grid topology. Currently, the impact of the topology on grid robustness is mainly as

  4. Teaching Science Through Pictorial Models During Read-Alouds

    Science.gov (United States)

    Oliveira, Alandeom W.; Rivera, Seema; Glass, Rory; Mastroianni, Michael; Wizner, Francine; Amodeo, Vincent

    2013-03-01

    This study examines how three elementary teachers refer to pictorial models (photographs, drawings, and cartoons) during science read-alouds. While one teacher used realistic photographs for the purpose of visually verifying facts about crystals, another employed analytical diagrams as heuristic tools to help students visualize complex target systems (rainbow formation and human eye functioning). Another teacher used fictional cartoons to engage students in analogical storytelling, communicating animal camouflage as analogous to human "blending in." However, teachers did not always explicitly convey the representational nature of pictorial models (analog and target as separate entities). It is argued that teachers need to become more aware of how they refer to pictorial models in children's science books and how to promote student visual literacy.

  5. Inferring Network Structure from Cascades

    CERN Document Server

    Ghonge, Sushrut

    2016-01-01

    Many physical, biological and social phenomena can be described by cascades taking place on a network. Often, the activity can be empirically observed, but not the underlying network of interactions. In this paper we solve the dynamics of general cascade processes. We then offer three topological inversion methods to infer the structure of any directed network given a set of cascade arrival times. Our forward and inverse formulas hold for a very general class of models where the activation probability of a node is a generic function of its degree and the number of its active neighbors. We report high success rates for synthetic and real networks, for 5 different cascade models.

  6. Genetic and Environmental Bases of Reading and Spelling: A Unified Genetic Dual Route Model

    Science.gov (United States)

    Bates, Timothy C.; Castles, Anne; Luciano, Michelle; Wright, Margaret J.; Coltheart, Max; Martin, Nicholas G.

    2007-01-01

    We develop and test a dual-route model of genetic effects on reading aloud and spelling, based on irregular and non-word reading and spelling performance assessed in 1382 monozygotic and dizygotic twins. As in earlier research, most of the variance in reading was due to genetic effects. However, there were three more specific conclusions: the…

  7. Exploring Gains in Reading and Mathematics Achievement among Regular and Exceptional Students Using Growth Curve Modeling

    Science.gov (United States)

    Shin, Tacksoo; Davison, Mark L.; Long, Jeffrey D.; Chan, Chi-Keung; Heistad, David

    2013-01-01

    Using four-wave longitudinal reading and mathematics data (4th to 7th grades) from a large urban school district, growth curve modeling was used as a tool for examining three research questions: Are achievement gaps closing in reading and mathematics? What are the associations between prior-achievement and growth across the reading and mathematics…

  8. Earthquake behavior of variable rupture- scale on active faults and application of the cascade-rupturing model

    Institute of Scientific and Technical Information of China (English)

    闻学泽

    2001-01-01

    This study reveals preliminarily the earthquake behavior of variable rupture-scale on active faults of the Chinese mainland, that is that on an individual fault portion earthquake¢s rupture-scale varies cycle to cycle, and hence earthquake¢s strength changes with time. The tendency of this variation has no necessity. On defining relative size of rupture scales, a statistical result shows that it is of the lowest probability that ruptures with the same scale occur in two successive cycles. While the rupture¢s scale in the preceding cycle is 2small2, the probability of the follow-ing rupture¢s scale being 2large2 is as many as 0.48. While the rupture¢s scale in the preceding cycle is 2middle2, the probability of the succeeding rupture being 2small2 or 2large2 scale is 0.69 or 0.25. While the rupture¢s scale in the preceding cycle is 2large2, the probability must be zero for the following rupture with 2large2 scale, and is 0.36 or 0.64 for the following rupture with 2small2 or 2middle2 scale. The author introduces and improves the cascade-rupturing model, and uses it to describe the variability and complexity of rupture scale on individual fault portions. Basic features of some active strike-slip faults on which cascade ruptures have occurred are summarized. Basing on these features the author proposes principles of cascade-rupture segmentation for this type of faults. As an ex-ample to application, the author segments one portion of the Anninghe fault zone, western Sichuan, for its future cascade rupture, and further assesses the probable strength and its corresponding probability of the coming earth-quake.

  9. Reading-Enhanced Word Problem Solving: A Theoretical Model

    Science.gov (United States)

    Capraro, Robert M.; Capraro, Mary Margaret; Rupley, William H.

    2012-01-01

    There is a reciprocal relationship between mathematics and reading cognition. Metacognitive training within reading-enhanced problem solving should facilitate students developing an awareness of what good readers do when reading for meaning in solving mathematical problems enabling them to apply these strategies. The constructs for each cognitive…

  10. A Model of Reading Comprehension in Chinese Elementary School Children

    Science.gov (United States)

    Yeung, Pui-sze; Ho, Connie Suk-han; Chan, David Wai-ock; Chung, Kevin Kien-hoa; Wong, Yau-kai

    2013-01-01

    The relationships of reading-related skills (rapid naming, morphological awareness, syntactic skills, discourse skills, and verbal working memory) and word reading to reading comprehension were examined among 248 Chinese fourth graders in Hong Kong. Multiple regression analysis results showed that syntactic skills (word order knowledge,…

  11. Learning Cascading

    CERN Document Server

    Covert, Michael

    2015-01-01

    This book is intended for software developers, system architects and analysts, big data project managers, and data scientists who wish to deploy big data solutions using the Cascading framework. You must have a basic understanding of the big data paradigm and should be familiar with Java development techniques.

  12. Spontaneous current-layer fragmentation and cascading reconnection in solar flares: I. Model and analysis

    CERN Document Server

    Bárta, Miroslav; Karlický, Marian; Skála, Jan

    2010-01-01

    Magnetic reconnection is commonly considered as a mechanism of solar (eruptive) flares. A deeper study of this scenario reveals, however, a number of open issues. Among them is the fundamental question, how the magnetic energy is transferred from large, accumulation scales to plasma scales where its actual dissipation takes place. In order to investigate this transfer over a broad range of scales we address this question by means of high-resolution MHD simulation. The simulation results indicate, that the magnetic-energy transfer to small scales is realized via a cascade of consecutive smaller and smaller flux-ropes (plasmoids), in analogy with the vortex-tube cascade in (incompressible) fluid dynamics. Both tearing and (driven) coalescence processes are equally important for the consecutive fragmentation of the magnetic field (and associated current density) to smaller elements. At the later stages a dynamic balance between tearing and coalescence processes reveals a steady (power-law) scaling typical for ca...

  13. Numerical modeling of microchannel gas flows in the transition flow regime via cascaded lattice Boltzmann method

    CERN Document Server

    Liu, Qing

    2016-01-01

    As a numerically accurate and computationally efficient mesoscopic numerical method, the lattice Boltzmann (LB) method has achieved great success in simulating microscale rarefied gas flows. In this paper, an LB method based on the cascaded collision operator is presented to simulate microchannel gas flows in the transition flow regime. The Bosanquet-type effective viscosity is incorporated into the cascaded lattice Boltzmann (CLB) method to account for the rarefaction effects. In order to gain accurate simulations and match the Bosanquet-type effective viscosity, the combined bounce-back/specular-reflection scheme with a modified second-order slip boundary condition is employed in the CLB method. The present method is applied to study gas flow in a microchannel with periodic boundary condition and gas flow in a long microchannel with pressure boundary condition over a wide range of Knudsen numbers. The predicted results, including the velocity profile, the mass flow rate, and the non-linear pressure deviatio...

  14. Numerical calculations of cosmic ray cascade in the Earth's atmosphere using different particle interaction models

    Science.gov (United States)

    Nesterenok, A. V.; Naidenov, V. O.

    2015-12-01

    The interaction of primary cosmic rays with the Earth's atmosphere is investigated using the simulation toolkit GEANT4. Two reference lists of physical processes - QGSP_BIC_HP and FTFP_BERT_HP - are used in the simulations of cosmic ray cascade in the atmosphere. The cosmic ray neutron fluxes are calculated for mean level of solar activity, high geomagnetic latitudes and sea level. The calculated fluxes are compared with the published results of other analogous simulations and with experimental data.

  15. Model approach for stress induced steroidal hormone cascade changes in severe mental diseases.

    Science.gov (United States)

    Volko, Claus D; Regidor, Pedro A; Rohr, Uwe D

    2016-03-01

    Stress was described by Cushing and Selye as an adaptation to a foreign stressor by the anterior pituitary increasing ACTH, which stimulates the release of glucocorticoid and mineralocorticoid hormones. The question is raised whether stress can induce additional steroidal hormone cascade changes in severe mental diseases (SMD), since stress is the common denominator. A systematic literature review was conducted in PubMed, where the steroidal hormone cascade of patients with SMD was compared to the impact of increasing stress on the steroidal hormone cascade (a) in healthy amateur marathon runners with no overtraining; (b) in healthy well-trained elite soldiers of a ranger training unit in North Norway, who were under extreme physical and mental stress, sleep deprivation, and insufficient calories for 1 week; and, (c) in soldiers suffering from post traumatic stress disorder (PTSD), schizophrenia (SI), and bipolar disorders (BD). (a) When physical stress is exposed moderately to healthy men and women for 3-5 days, as in the case of amateur marathon runners, only few steroidal hormones are altered. A mild reduction in testosterone, cholesterol and triglycerides is detected in blood and in saliva, but there was no decrease in estradiol. Conversely, there is an increase of the glucocorticoids, aldosterone and cortisol. Cellular immunity, but not specific immunity, is reduced for a short time in these subjects. (b) These changes are also seen in healthy elite soldiers exposed to extreme physical and mental stress but to a somewhat greater extent. For instance, the aldosterone is increased by a factor of three. (c) In SMD, an irreversible effect on the entire steroidal hormone cascade is detected. Hormones at the top of the cascade, such as cholesterol, dehydroepiandrosterone (DHEA), aldosterone and other glucocorticoids, are increased. However, testosterone and estradiol and their metabolites, and other hormones at the lower end of the cascade, seem to be reduced. 1

  16. Cascade trailing-edge noise modeling using a mode-matching technique and the edge-dipole theory

    Science.gov (United States)

    Roger, Michel; François, Benjamin; Moreau, Stéphane

    2016-11-01

    An original analytical approach is proposed to model the broadband trailing-edge noise produced by high-solidity outlet guide vanes in an axial turbomachine. The model is formulated in the frequency domain and first in two dimensions for a preliminary assessment of the method. In a first step the trailing-edge noise sources of a single vane are shown to be equivalent to the onset of a so-called edge dipole, the direct field of which is expanded in a series of plane-wave modes. A criterion for the distance of the dipole to the trailing-edge and a scaling of its amplitude is defined to yield a robust model. In a second step the diffraction of each plane-wave mode is derived considering the cascade as an array of bifurcated waveguides and using a mode-matching technique. The cascade response is finally synthesized by summing the diffracted fields of all cut-on modes to yield upstream and downstream sound power spectral densities. The obtained spectral shapes are physically consistent and the present results show that upstream radiation is typically 3 dB higher than downstream radiation, which has been experimentally observed previously. Even though the trailing-edge noise sources are not vane-to-vane correlated their radiation is strongly determined by a cascade effect that consequently must be accounted for. The interest of the approach is that it can be extended to a three-dimensional annular configuration without resorting to a strip theory approach. As such it is a promising and versatile alternative to previously published methods.

  17. A Study of Classics-Reading Curriculum, Classics-Reading Promotion, and Classics-Reading Effect Modeling Exploration in Elementary Schools

    Directory of Open Access Journals (Sweden)

    Chuen-An Tang

    2014-01-01

    Full Text Available The purposes of this study are to test reliabilities and validities of classics-reading curriculum (CRC scale, classics-reading promotion (CRP scale, and classics-reading effect (CRE scale and to examine the relationships between CRC, CRP, and CRE in elementary schools through applying CORPS framework. The pilot sample and formal sample contain 141 and 500 participants from elementary school faculties and classics-reading volunteers in the north, central, south, and east regions of Taiwan. The findings indicate that Cronbach α coefficients of curriculum cognition (CC, curriculum teaching (CT, inside-school promotion (IP, outside-school promotion (EP, learning effect (LE, and class management effect (CME subscales are .88, .85, .93, .91, .91, .94, respectively, through exploratory factor analysis and they have good internal reliabilities and construct validities, respectively, through confirmatory factor analysis. Moreover, CC, CT, IP, and EP have positive influences on LE (standardized coefficients .34, .25, .14, and .22 and on CME (standardized coefficients .41, .14, .14, and .20, respectively. CC, CT, IP, and EP can explain 69% of LE and 61% of CME. The model is supported by the data. Lastly, this study proposes some suggestions regarding the classics-reading education for elementary schools.

  18. Computational Model of Music Sight Reading: A Reinforcement Learning Approach

    CERN Document Server

    Yahya, Keyvan

    2010-01-01

    Although the Music Sight Reading process usually has been studied from the cognitive or neurological view points, but the computational learning methods like the Reinforcement Learning have not yet been used to modeling of such processes. In this paper with regards to essential properties of our specific problem, we consider the value function concept and will indicate that the optimum policy can be obtained by the method we offer without to be getting involved with computing of the complex value functions which are in most of cases inexact. Also, the algorithm we will offer here is somehow a PDE based algorithm which is associated with a stochastic optimization programming and we consider that in this case, this one is more applicable than the normative algorithms like temporal difference method.

  19. A model of the TeV flare of Cygnus X-1: electron acceleration and extended pair cascades

    CERN Document Server

    Zdziarski, A A; Bednarek, W

    2008-01-01

    We consider theoretical models of emission of TeV photons by Cyg X-1 during a flare discovered by the MAGIC detector. We study acceleration of electrons to energies sufficient for TeV emission, and find the emission site is allowed to be close to the black hole. We then consider pair absorption in the photon field of the central X-ray source and a surrounding accretion disc, and find its optical depth is 3 TeV, in which photons travel far away from the star, initiating a spatially extended pair cascade. This qualitatively explains the observed TeV spectrum, though still not its exact shape.

  20. Optimization of contrast-enhanced breast imaging: Analysis using a cascaded linear system model.

    Science.gov (United States)

    Hu, Yue-Houng; Scaduto, David A; Zhao, Wei

    2017-01-01

    Contrast-enhanced (CE) breast imaging involves the injection contrast agents (i.e., iodine) to increase conspicuity of malignant lesions. CE imaging may be used in conjunction with digital mammography (DM) or digital breast tomosynthesis (DBT) and has shown promise in improving diagnostic specificity. Both CE-DM and CE-DBT techniques require optimization as clinical diagnostic tools. Physical factors including x-ray spectra, subtraction technique, and the signal from iodine contrast, must be considered to provide the greatest object detectability and image quality. We developed a cascaded linear system model (CLSM) for the optimization of CE-DM and CE-DBT employing dual energy (DE) subtraction or temporal (TE) subtraction. We have previously developed a CLSM for DBT implemented with an a-Se flat panel imager (FPI) and filtered backprojection (FBP) reconstruction algorithm. The model is used to track image quality metrics - modulation transfer function (MTF) and noise power spectrum (NPS) - at each stage of the imaging chain. In this study, the CLSM is extended for CE breast imaging. The effect of x-ray spectrum (varied by changing tube potential and the filter) and DE and TE subtraction techniques on breast structural noise was measured was studied and included as a deterministic source of noise in the CLSM. From the two-dimensional (2D) and three-dimensional (3D) MTF and NPS, the ideal observer signal-to-noise ratio (SNR), also known as the detectability index (d'), may be calculated. Using d' as a FOM, we discuss the optimization of CE imaging for the task of iodinated contrast object detection within structured backgrounds. Increasing x-ray energy was determined to decrease the magnitude of structural noise and not its correlation. By performing DE subtraction, the magnitude of the structural noise was further reduced at the expense of increased stochastic (quantum and electronic) noise. TE subtraction exhibited essentially no residual structural noise at the

  1. Thinking outside the boxes: Using current reading models to assess and treat developmental surface dyslexia.

    Science.gov (United States)

    Law, Caroline; Cupples, Linda

    2017-03-01

    Improving the reading performance of children with developmental surface dyslexia has proved challenging, with limited generalisation of reading skills typically reported after intervention. The aim of this study was to provide tailored, theoretically motivated intervention to two children with developmental surface dyslexia. Our objectives were to improve their reading performance, and to evaluate the utility of current reading models in therapeutic practice. Detailed reading and cognitive profiles for two male children with developmental surface dyslexia were compared to the results obtained by age-matched control groups. The specific area of single-word reading difficulty for each child was identified within the dual route model (DRM) of reading, following which a theoretically motivated intervention programme was devised. Both children showed significant improvements in single-word reading ability after training, with generalisation effects observed for untrained words. However, the assessment and intervention results also differed for each child, reinforcing the view that the causes and consequences of developmental dyslexia, even within subtypes, are not homogeneous. Overall, the results of the interventions corresponded more closely with the DRM than other current reading models, in that real word reading improved in the absence of enhanced nonword reading for both children.

  2. Cascading model uncertainty from medium range weather forecasts (10 days) through a rainfall-runoff model to flood inundation predictions within the European Flood Forecasting System (EFFS)

    OpenAIRE

    Pappenberger, F.; K. J. Beven; N. M. Hunter; Bates, P. D.; B. T. Gouweleeuw; Thielen, J.; A. P. J. De De Roo

    2005-01-01

    International audience; The political pressure on the scientific community to provide medium to long term flood forecasts has increased in the light of recent flooding events in Europe. Such demands can be met by a system consisting of three different model components (weather forecast, rainfall-runoff forecast and flood inundation forecast) which are all liable to considerable uncertainty in the input, output and model parameters. Thus, an understanding of cascaded uncertainties is a necessa...

  3. Modelling and Extremum Seeking Control of a Cascade of Two Anaerobic Bioreactors

    Directory of Open Access Journals (Sweden)

    Ivan Simeonov

    2011-05-01

    Full Text Available The principle of extremum seeking control has been applied on a cascade of two anaerobic bioreactors using the dilution rate as control action and the biogas flow rates as measured outputs to be maximized. In all cases maximum biogas flow rate with sensible decrease of the general output depollution parameter (compared to the case of one single bioreactor has been obtained, starting from different initial conditions. With the same algorithm, good performances have been obtained in the presence of variations of the inlet organics. Its implication for biotechnology may result in substantial economic benefits.

  4. Anglocentrism in reading acquisition models? A study in a language with transparent orthography

    Directory of Open Access Journals (Sweden)

    Beatriz Diuk

    2013-12-01

    Full Text Available The present research aimed to check Share’s (2008 thesis about conventional reading acquisition models in a group of Argentinean children. This author proposes that reading models developed for English need to be reviewed when children are learning to read in a language with transparent orthography. Share questions the idea of learning proceeds in stages, the importance given to reading accuracy over speed and the relevance of phonological processing. A group of 52 children from low-income families were tested on letter knowledge, phonological awareness, rapid naming and reading of frequent words at the beginning and the middle of first grade. Additionally, children’s word and pseudo-word reading skills were tested at the end of first and second grade. Results showed that most children never resorted to non-phonological strategies as it is usually done by their equals in English. By the end of second grade the group had reached a high level of accuracy in reading, but important differences were found in reading speed. These results support Share’s (2008 proposal since reading acquisition did not develop in a series of stages but could be described as a continuous process in which children gradually increase their phonological recoding abilities and achieve accuracy early on. Therefore individual differences in reading speed become a critical aspect of reading.

  5. Investigation of Positively Curved Blade in Compressor Cascade Based on Transition Model

    Science.gov (United States)

    Chen, Shaowen; Lan, Yunhe; Zhou, Zhihua; Wang, Songtao

    2016-06-01

    Experiment and numerical simulation of flow transition in a compressor cascade with positively curved blade is carried out in a low speed. In the experimental investigation, the outlet aerodynamic parameters are measured using a five-hole aerodynamic probe, and an ink-trace flow visualization is applied to the cascade surface. The effects of transition flow on the boundary layer development, three-dimensional flow separation and aerodynamic performance are studied. The feasibility of a commercial computational fluid dynamic code is validated and the numerical results show a good agreement with experimental data. The blade-positive curving intensifies the radial force from the endwalls to the mid-span near the suction surface, which leads to the smaller scope of the intermittent region, the lesser extents of turbulence intensity and the shorter radial height of the separation bubble near the endwalls, but has little influence on the flow near the mid-span. The large passage vortex is divided into two smaller shedding vortexes under the impact of the radial pressure gradient due to the positively curved blade. The new concentrated shedding vortex results in an increase in the turbulence intensity and secondary flow loss of the corresponding region.

  6. Long term reliability study and life time model of quantum cascade lasers

    Science.gov (United States)

    Xie, Feng; Nguyen, Hong-Ky; Leblanc, Herve; Hughes, Larry; Wang, Jie; Wen, Jianguo; Miller, Dean J.; Lascola, Kevin

    2016-09-01

    Here, we present results of quantum cascade laser lifetime tests under various aging conditions including an accelerated life test. The total accumulated life time exceeds 1.5 × 106 device hours. The longest single device aging time was 46 500 hours without failure in the room temperature aging test. Four failures were found in a group of 19 devices subjected to the accelerated life test with a heat-sink temperature of 60 °C and a continuous-wave current of 1 A. Failure mode analyses revealed that thermally induced oxidation of InP in the semi-insulating layer is the cause of failure. An activation energy of 1.2 eV is derived from the dependence of the failure rate on laser core temperature. The mean time to failure of the quantum cascade lasers operating at a typical condition with the current density of 5 kA/cm2 and heat-sink temperature of 25 °C is expected to be 809 000 hours.

  7. Cross sections of proton- and neutron-induced reactions by the Liège intranuclear cascade model

    Science.gov (United States)

    Chen, Jian; Dong, Tiekuang; Ren, Zhongzhou

    2016-06-01

    The purpose of the paper is mainly to test the validity of the Liège intranuclear cascade (INCL) model in calculating the cross sections of proton-induced reactions for cosmogenic nuclei using the newly compiled database of proton cross sections. The model calculations of 3He display the rising tendency of cross sections with the increase of energy, in accordance with the experimental data. Meanwhile, the differences between the theoretical results and experimental data of production cross sections (10Be and 26Al) are generally within a factor of 3, meaning that the INCL model works quite well for the proton-induced reactions. Based on the good agreement, we predict the production cross sections of 26Al from reactions n + 27Al, n + 28Si, and n + 40Ca and those of 10Be from reactions n + 16O and n + 28Si. The results also show a good agreement with a posteriori excitation functions.

  8. On the Impact of Diagram Layout: How Are Models Actually Read?

    DEFF Research Database (Denmark)

    Störrle, Harald; Baltsen, Nick; Christoffersen, Henrik;

    2014-01-01

    This poster presents the latest results from a very large eye tracking study (n=29) that explores how modelers read UML diagrams. We find that various factors like layout quality, modeler experience, and diagram type lead to significant differences in diagram reading strategies. We derive element...

  9. MODEL PENGEMBANGAN SOAL READING TOEFL BERBASIS TEKS-TEKS KEISLAMAN

    Directory of Open Access Journals (Sweden)

    IRWAN IRWAN

    2017-03-01

    Full Text Available Problem of this research is the unfamiliarity of the topics in TOEFL test. Many of the topics are talking about American and Europe.  They are about American science, American history, American economic system, American culture and European culture.  The topics above are not familiar to the students of State Islamic College because they seldom study about the topic. To answer the TOEFL tes it will be better for us to have background knowledge about the topics of the reading.  If we are familiar with the topic, it will help us to be easy in answering and understanding about the text.  This research used Research & Development (R&D approach.  The sample of the try out test for developing these questions are the sixth semester English students of STAIN Batusangkar.  The data were analyzed by using Kappa model to differenciate the items difficulties, items differenciation, trapping model, validity and reliability.  The product of this research then revised for three times.  Then, the product is also commented and analyzed by the experts.  After analyzing the revision of the product, the result finally getting ready to be used for a test.

  10. A multifaceted model for designing reading development programmes for L2 learners at tertiary level

    Directory of Open Access Journals (Sweden)

    Naomi Boakye

    2012-04-01

    Full Text Available Socio-affective issues are generally acknowledged as important in reading development. However, most intervention programmes focus on cognitive aspects of reading, and do not explicitly accommodate socio-affective factors such as attitude, motivation, interest, and background of students. This paper argues for the inclusion of both cognitive and socio-affective scaffolding in tertiary-level reading development programmes. Based on a number of second language teaching techniques, and grounded in Guthrie and Wigfield’s (2000 engagement model, I propose a multifaceted model on which to map reading instruction/intervention at tertiary level that combines both affective and cognitive factors.

  11. Modeling cascading diffusion of new energy technologies: case study of residential solid oxide fuel cells in the US and internationally.

    Science.gov (United States)

    Herron, Seth; Williams, Eric

    2013-08-06

    Subsidy programs for new energy technologies are motivated by the experience curve: increased adoption of a technology leads to learning and economies of scale that lower costs. Geographic differences in fuel prices and climate lead to large variability in the economic performance of energy technologies. The notion of cascading diffusion is that regions with favorable economic conditions serve as the basis to build scale and reduce costs so that the technology becomes attractive in new regions. We develop a model of cascading diffusion and implement via a case study of residential solid oxide fuel cells (SOFCs) for combined heating and power. We consider diffusion paths within the U.S. and internationally. We construct market willingness-to-pay curves and estimate future manufacturing costs via an experience curve. Combining market and cost results, we find that for rapid cost reductions (learning rate = 25%), a modest public subsidy can make SOFC investment profitable for 20-160 million households. If cost reductions are slow however (learning rate = 15%), residential SOFCs may not become economically competitive. Due to higher energy prices in some countries, international diffusion is more favorable than domestic, mitigating much of the uncertainty in the learning rate.

  12. Influence of interferometric cross talk in a cascade of 10-Gbit/s wavelength routers and an improved Gaussian cross talk model

    DEFF Research Database (Denmark)

    Liu, Fenghai; Rasmussen, Christian Jørgen; Pedersen, Rune Johan Skullerud

    1998-01-01

    Integrated optical N×N wavelength routers based on arrayed-waveguide gratings (AWGs) are likely to become key devices in future WDM networks. A cascade of wavelength routers is formed when several N×N networks are interconnected. Due to the nonideal transfer function of physical AWGs, a node...... will receive not only the signal from the node it is connected to, but also cross talk at the same wavelength from the other nodes. In a cascade of AWG routers, the cross talk will accumulate and thereby limit the number of stages. The Gaussian cross talk model is considered to be a worst-case model when...... for investigation of router cascades. Very good agreement is demonstrated between the measured penalty and the penalty predicted from our improved Gaussian cross talk model...

  13. A Developmental Cascade Model of Behavioral Sleep Problems and Emotional and Attentional Self-Regulation Across Early Childhood.

    Science.gov (United States)

    Williams, Kate E; Berthelsen, Donna; Walker, Sue; Nicholson, Jan M

    2017-01-01

    This article documents the longitudinal and reciprocal relations among behavioral sleep problems and emotional and attentional self-regulation in a population sample of 4,109 children participating in Growing Up in Australia: The Longitudinal Study of Australian Children (LSAC)-Infant Cohort. Maternal reports of children's sleep problems and self-regulation were collected at five time-points from infancy to 8-9 years of age. Longitudinal structural equation modeling supported a developmental cascade model in which sleep problems have a persistent negative effect on emotional regulation, which in turn contributes to ongoing sleep problems and poorer attentional regulation in children over time. Findings suggest that sleep behaviors are a key target for interventions that aim to improve children's self-regulatory capacities.

  14. Eco-hydrologic model cascades: Simulating land use and climate change impacts on hydrology, hydraulics and habitats for fish and macroinvertebrates.

    Science.gov (United States)

    Guse, Björn; Kail, Jochem; Radinger, Johannes; Schröder, Maria; Kiesel, Jens; Hering, Daniel; Wolter, Christian; Fohrer, Nicola

    2015-11-15

    Climate and land use changes affect the hydro- and biosphere at different spatial scales. These changes alter hydrological processes at the catchment scale, which impact hydrodynamics and habitat conditions for biota at the river reach scale. In order to investigate the impact of large-scale changes on biota, a cascade of models at different scales is required. Using scenario simulations, the impact of climate and land use change can be compared along the model cascade. Such a cascade of consecutively coupled models was applied in this study. Discharge and water quality are predicted with a hydrological model at the catchment scale. The hydraulic flow conditions are predicted by hydrodynamic models. The habitat suitability under these hydraulic and water quality conditions is assessed based on habitat models for fish and macroinvertebrates. This modelling cascade was applied to predict and compare the impacts of climate- and land use changes at different scales to finally assess their effects on fish and macroinvertebrates. Model simulations revealed that magnitude and direction of change differed along the modelling cascade. Whilst the hydrological model predicted a relevant decrease of discharge due to climate change, the hydraulic conditions changed less. Generally, the habitat suitability for fish decreased but this was strongly species-specific and suitability even increased for some species. In contrast to climate change, the effect of land use change on discharge was negligible. However, land use change had a stronger impact on the modelled nitrate concentrations affecting the abundances of macroinvertebrates. The scenario simulations for the two organism groups illustrated that direction and intensity of changes in habitat suitability are highly species-dependent. Thus, a joined model analysis of different organism groups combined with the results of hydrological and hydrodynamic models is recommended to assess the impact of climate and land use changes on

  15. Developmental relations between vocabulary knowledge and reading comprehension: a latent change score modeling study.

    Science.gov (United States)

    Quinn, Jamie M; Wagner, Richard K; Petscher, Yaacov; Lopez, Danielle

    2015-01-01

    The present study followed a sample of first-grade (N = 316, Mage = 7.05 at first test) through fourth-grade students to evaluate dynamic developmental relations between vocabulary knowledge and reading comprehension. Using latent change score modeling, competing models were fit to the repeated measurements of vocabulary knowledge and reading comprehension to test for the presence of leading and lagging influences. Univariate models indicated growth in vocabulary knowledge, and reading comprehension was determined by two parts: constant yearly change and change proportional to the previous level of the variable. Bivariate models indicated previous levels of vocabulary knowledge acted as leading indicators of reading comprehension growth, but the reverse relation was not found. Implications for theories of developmental relations between vocabulary and reading comprehension are discussed.

  16. Information cascade on networks

    Science.gov (United States)

    Hisakado, Masato; Mori, Shintaro

    2016-05-01

    In this paper, we discuss a voting model by considering three different kinds of networks: a random graph, the Barabási-Albert (BA) model, and a fitness model. A voting model represents the way in which public perceptions are conveyed to voters. Our voting model is constructed by using two types of voters-herders and independents-and two candidates. Independents conduct voting based on their fundamental values; on the other hand, herders base their voting on the number of previous votes. Hence, herders vote for the majority candidates and obtain information relating to previous votes from their networks. We discuss the difference between the phases on which the networks depend. Two kinds of phase transitions, an information cascade transition and a super-normal transition, were identified. The first of these is a transition between a state in which most voters make the correct choices and a state in which most of them are wrong. The second is a transition of convergence speed. The information cascade transition prevails when herder effects are stronger than the super-normal transition. In the BA and fitness models, the critical point of the information cascade transition is the same as that of the random network model. However, the critical point of the super-normal transition disappears when these two models are used. In conclusion, the influence of networks is shown to only affect the convergence speed and not the information cascade transition. We are therefore able to conclude that the influence of hubs on voters' perceptions is limited.

  17. Experimental study on cascaded attitude angle control of a multi-rotor unmanned aerial vehicle with the simple internal model control method

    Energy Technology Data Exchange (ETDEWEB)

    Song, Jun Beom [Dept. of Aviation Maintenance, Dongwon Institute of Science and Technology, Yangsan (Korea, Republic of); Byun, Young Seop; Jeong, Jin Seok; Kim, Jeong; Kang, Beom Soo [Dept. of Aerospace Engineering, Pusan National University, Busan (Korea, Republic of)

    2016-11-15

    This paper proposes a cascaded control structure and a method of practical application for attitude control of a multi-rotor Unmanned aerial vehicle (UAV). The cascade control, which has tighter control capability than a single-loop control, is rarely used in attitude control of a multi-rotor UAV due to the input-output relation, which is no longer simply a set-point to Euler angle response transfer function of a single-loop PID control, but there are multiply measured signals and interactive control loops that increase the complexity of evaluation in conventional way of design. However, it is proposed in this research a method that can optimize a cascade control with a primary and secondary loops and a PID controller for each loop. An investigation of currently available PID-tuning methods lead to selection of the Simple internal model control (SIMC) method, which is based on the Internal model control (IMC) and direct-synthesis method. Through the analysis and experiments, this research proposes a systematic procedure to implement a cascaded attitude controller, which includes the flight test, system identification and SIMC-based PID-tuning. The proposed method was validated successfully from multiple applications where the application to roll axis lead to a PID-PID cascade control, but the application to yaw axis lead to that of PID-PI.

  18. Cognitive Component of Componential Model of Reading Applied to Different Orthographies

    Science.gov (United States)

    Joshi, R. Malatesha; Tao, Sha; Aaron, P. G.; Quiroz, Blanca

    2012-01-01

    Whether the simple view of reading (SVR) as incorporated in the componential model of reading (CMR) is applicable to other orthographies than English was explored in this study. Spanish, with transparent orthography and Chinese, with opaque orthography were selected because of their diverse characteristics. The first part reports a study of…

  19. Cognitive Component of Componential Model of Reading Applied to Different Orthographies

    Science.gov (United States)

    Joshi, R. Malatesha; Tao, Sha; Aaron, P. G.; Quiroz, Blanca

    2012-01-01

    Whether the simple view of reading (SVR) as incorporated in the componential model of reading (CMR) is applicable to other orthographies than English was explored in this study. Spanish, with transparent orthography and Chinese, with opaque orthography were selected because of their diverse characteristics. The first part reports a study of…

  20. Validation of a Cognitive Diagnostic Model across Multiple Forms of a Reading Comprehension Assessment

    Science.gov (United States)

    Clark, Amy K.

    2013-01-01

    The present study sought to fit a cognitive diagnostic model (CDM) across multiple forms of a passage-based reading comprehension assessment using the attribute hierarchy method. Previous research on CDMs for reading comprehension assessments served as a basis for the attributes in the hierarchy. The two attribute hierarchies were fit to data from…

  1. Testing and Refining the Direct and Inferential Mediation Model of Reading Comprehension

    Science.gov (United States)

    Cromley, Jennifer G.; Azevedo, Roger

    2007-01-01

    A significant proportion of American high school students struggle with reading comprehension. Theoretical models of reading comprehension might help researchers understand these difficulties, because they can point to variables that make the largest contributions to comprehension. On the basis of an extensive review of the literature, we created…

  2. Monte-Carlo Modeling of Parameters of a Subcritical Cascade Reactor Based on MSBR and LMFBR Technologies

    CERN Document Server

    Bznuni, S A; Zhamkochyan, V M; Polanski, A; Sosnin, A N; Khudaverdyan, A H

    2001-01-01

    Parameters of a subcritical cascade reactor driven by a proton accelerator and based on a primary lead-bismuth target, main reactor constructed analogously to the molten salt breeder (MSBR) reactor core and a booster-reactor analogous to the core of the BN-350 liquid metal cooled fast breeder reactor (LMFBR). It is shown by means of Monte-Carlo modeling that the reactor under study provides safe operation modes (k_{eff}=0.94-0.98), is apable to transmute effectively radioactive nuclear waste and reduces by an order of magnitude the requirements on the accelerator beam current. Calculations show that the maximal neutron flux in the thermal zone is 10^{14} cm^{12}\\cdot s^_{-1}, in the fast booster zone is 5.12\\cdot10^{15} cm^{12}\\cdot s{-1} at k_{eff}=0.98 and proton beam current I=2.1 mA.

  3. Aggression, Sibling Antagonism, and Theory of Mind During the First Year of Siblinghood: A Developmental Cascade Model.

    Science.gov (United States)

    Song, Ju-Hyun; Volling, Brenda L; Lane, Jonathan D; Wellman, Henry M

    2016-07-01

    A developmental cascade model was tested to examine longitudinal associations among firstborn children's aggression, theory of mind (ToM), and antagonism toward their younger sibling during the 1st year of siblinghood. Aggression and ToM were assessed before the birth of a sibling and 4 and 12 months after the birth, and antagonism was examined at 4 and 12 months in a sample of 208 firstborn children (initial Mage  = 30 months, 56% girls) from primarily European American, middle-class families. Firstborns' aggression consistently predicted high sibling antagonism both directly and through poorer ToM. Results highlight the importance of examining longitudinal influences across behavioral, social-cognitive, and relational factors that are closely intertwined even from the early years of life.

  4. PACIAE 2.1: An updated issue of the parton and hadron cascade model PACIAE 2.0

    Science.gov (United States)

    Sa, Ben-Hao; Zhou, Dai-Mei; Yan, Yu-Liang; Dong, Bao-Guo; Cai, Xu

    2013-05-01

    We have updated the parton and hadron cascade model PACIAE 2.0 (cf. Ben-Hao Sa, Dai-Mei Zhou, Yu-Liang Yan, Xiao-Mei Li, Sheng-Qin Feng, Bao-Guo Dong, Xu Cai, Comput. Phys. Comm. 183 (2012) 333.) to the new issue of PACIAE 2.1. The PACIAE model is based on PYTHIA. In the PYTHIA model, once the hadron transverse momentum pT is randomly sampled in the string fragmentation, the px and py components are originally put on the circle with radius pT randomly. Now it is put on the circumference of ellipse with half major and minor axes of pT(1+δp) and pT(1-δp), respectively, in order to better investigate the final state transverse momentum anisotropy. New version program summaryManuscript title: PACIAE 2.1: An updated issue of the parton and hadron cascade model PACIAE 2.0 Authors: Ben-Hao Sa, Dai-Mei Zhou, Yu-Liang Yan, Bao-Guo Dong, and Xu Cai Program title: PACIAE version 2.1 Journal reference: Catalogue identifier: Licensing provisions: none Programming language: FORTRAN 77 or GFORTRAN Computer: DELL Studio XPS and others with a FORTRAN 77 or GFORTRAN compiler Operating system: Linux or Windows with FORTRAN 77 or GFORTRAN compiler RAM: ≈ 1GB Number of processors used: Supplementary material: Keywords: relativistic nuclear collision; PYTHIA model; PACIAE model Classification: 11.1, 17.8 External routines/libraries: Subprograms used: Catalogue identifier of previous version: aeki_v1_0* Journal reference of previous version: Comput. Phys. Comm. 183(2012)333. Does the new version supersede the previous version?: Yes* Nature of problem: PACIAE is based on PYTHIA. In the PYTHIA model, once the hadron transverse momentum(pT)is randomly sampled in the string fragmentation, thepxandpycomponents are randomly placed on the circle with radius ofpT. This strongly cancels the final state transverse momentum asymmetry developed dynamically. Solution method: Thepxandpycomponent of hadron in the string fragmentation is now randomly placed on the circumference of an ellipse with

  5. Daily optimized model for long-term operation of the Three Gorges-Gezhouba Cascade Power Stations

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper presents the step-by-step genetic algorithm based on artificial intelligence guidance and builds a long-term daily optimized operating model for the Three Gorges-Gezhouba Hydropower Complex with single generating set as the based operating unit.Actual operating data from 2004to 2006 are used to verify the model,and results show that the simulation accuracy determined by measuring the total amount of cascade power generation reaches 99.66%.Statistic hydrological data of normal years and actual data of three years of 2004-2006 are respectively used to perform an optimized prediction of the power generation process and benefits in future when the water stored in the TGP Reservoir reaches 175 m level and power generation benefits under different operation modes,such as delayed subsiding water level,advance water storage,and adopting of different flood-limited water levels,are forecasted.In the case of years with normal inflows,the total amount of cascade power generation running on current specifications reaches 107500 GWh per year.If the commencement of water storage after the flood season is moved forward by 20 days,the amount of power generation can be increased by 3400 GWh per year.If the limited water level in the flood season is raised by three to five meters,the amount of power generation can be increased by 1600 to 3200 GWh per year.If the commencement of water storage is moved forward while the maximum water level allowed in the flood season is raised,the amount of power generation can be increased by 6400 GWh per year.

  6. The Implementation of C-ID, R2D2 Model on Learning Reading Comprehension

    Science.gov (United States)

    Rayanto, Yudi Hari; Rusmawan, Putu Ngurah

    2016-01-01

    The purposes of this research are to find out, (1) whether C-ID, R2D2 model is effective to be implemented on learning Reading comprehension, (2) college students' activity during the implementation of C-ID, R2D2 model on learning Reading comprehension, and 3) college students' learning achievement during the implementation of C-ID, R2D2 model on…

  7. TOWARDS A REALIZATION OF AN HOLISTIC MODEL OF TEACHING READING IN THE EFL CLASS IN CHINA

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The teaching of reading in the EFL class in China is supposed to be the most important course forEnglish learners in colleges and universities because it is expected to fulfil two tasks:the develop-ment of reading skills and the development of language skills.The former set of skills is assigned tothe course called Extensive Reading,which is top-down oriented,and,like the top-down model be-fore 1980’s,its emphasis on the language competence such as syntax and vocabulary often leads to"wild guessing"and misunderstanding.Another reading course,Intensive Reading,is supposed to beresponsible for the latter set of skills.This bottom-up manner of reading often results in word-to-word reading and also causes miscomprehension.The Holistic Model of Reading,as developed on thebasis of interactive models with particular concern over the Chinese learning environment,attemptsto combine the two courses into one and the result,as our studies show,turns out to be promising.

  8. A cascaded QSAR model for efficient prediction of overall power conversion efficiency of all-organic dye-sensitized solar cells.

    Science.gov (United States)

    Li, Hongzhi; Zhong, Ziyan; Li, Lin; Gao, Rui; Cui, Jingxia; Gao, Ting; Hu, Li Hong; Lu, Yinghua; Su, Zhong-Min; Li, Hui

    2015-05-30

    A cascaded model is proposed to establish the quantitative structure-activity relationship (QSAR) between the overall power conversion efficiency (PCE) and quantum chemical molecular descriptors of all-organic dye sensitizers. The cascaded model is a two-level network in which the outputs of the first level (JSC, VOC, and FF) are the inputs of the second level, and the ultimate end-point is the overall PCE of dye-sensitized solar cells (DSSCs). The model combines quantum chemical methods and machine learning methods, further including quantum chemical calculations, data division, feature selection, regression, and validation steps. To improve the efficiency of the model and reduce the redundancy and noise of the molecular descriptors, six feature selection methods (multiple linear regression, genetic algorithms, mean impact value, forward selection, backward elimination, and +n-m algorithm) are used with the support vector machine. The best established cascaded model predicts the PCE values of DSSCs with a MAE of 0.57 (%), which is about 10% of the mean value PCE (5.62%). The validation parameters according to the OECD principles are R(2) (0.75), Q(2) (0.77), and Qcv2 (0.76), which demonstrate the great goodness-of-fit, predictivity, and robustness of the model. Additionally, the applicability domain of the cascaded QSAR model is defined for further application. This study demonstrates that the established cascaded model is able to effectively predict the PCE for organic dye sensitizers with very low cost and relatively high accuracy, providing a useful tool for the design of dye sensitizers with high PCE.

  9. New potentialities of the Li\\`ege intranuclear cascade (INCL) model for reactions induced by nucleons and light charged particles

    CERN Document Server

    Boudard, Alain; David, Jean-Christophe; Leray, Sylvie; Mancusi, Davide

    2012-01-01

    The new version (INCL4.6) of the Li`ege intranuclear cascade (INC) model for the description of spallation reactions is presented in detail. Compared to the standard version (INCL4.2), it incorporates several new features, the most important of which are: (i) the inclusion of cluster production through a dynamical phase space coalescence model, (ii) the Coulomb deflection for entering and outgoing charged particles, (iii) the improvement of the treatment of Pauli blocking and of soft collisions, (iv) the introduction of experimental threshold values for the emission of particles, (v) the improvement of pion dynamics, (vi) a detailed procedure for the treatment of light-cluster induced reactions taking care of the effects of binding energy of the nucleons inside the incident cluster and of the possible fusion reaction at low energy. Performances of the new model concerning nucleon-induced reactions are illustrated. Whenever necessary, the INCL4.6 model is coupled to the ABLA07 deexcitation model and the respec...

  10. Multifractality, imperfect scaling and hydrological properties of rainfall time series simulated by continuous universal multifractal and discrete random cascade models

    Science.gov (United States)

    Serinaldi, F.

    2010-12-01

    Discrete multiplicative random cascade (MRC) models were extensively studied and applied to disaggregate rainfall data, thanks to their formal simplicity and the small number of involved parameters. Focusing on temporal disaggregation, the rationale of these models is based on multiplying the value assumed by a physical attribute (e.g., rainfall intensity) at a given time scale L, by a suitable number b of random weights, to obtain b attribute values corresponding to statistically plausible observations at a smaller L/b time resolution. In the original formulation of the MRC models, the random weights were assumed to be independent and identically distributed. However, for several studies this hypothesis did not appear to be realistic for the observed rainfall series as the distribution of the weights was shown to depend on the space-time scale and rainfall intensity. Since these findings contrast with the scale invariance assumption behind the MRC models and impact on the applicability of these models, it is worth studying their nature. This study explores the possible presence of dependence of the parameters of two discrete MRC models on rainfall intensity and time scale, by analyzing point rainfall series with 5-min time resolution. Taking into account a discrete microcanonical (MC) model based on beta distribution and a discrete canonical beta-logstable (BLS), the analysis points out that the relations between the parameters and rainfall intensity across the time scales are detectable and can be modeled by a set of simple functions accounting for the parameter-rainfall intensity relationship, and another set describing the link between the parameters and the time scale. Therefore, MC and BLS models were modified to explicitly account for these relationships and compared with the continuous in scale universal multifractal (CUM) model, which is used as a physically based benchmark model. Monte Carlo simulations point out that the dependence of MC and BLS

  11. Multifractality, imperfect scaling and hydrological properties of rainfall time series simulated by continuous universal multifractal and discrete random cascade models

    Directory of Open Access Journals (Sweden)

    F. Serinaldi

    2010-12-01

    Full Text Available Discrete multiplicative random cascade (MRC models were extensively studied and applied to disaggregate rainfall data, thanks to their formal simplicity and the small number of involved parameters. Focusing on temporal disaggregation, the rationale of these models is based on multiplying the value assumed by a physical attribute (e.g., rainfall intensity at a given time scale L, by a suitable number b of random weights, to obtain b attribute values corresponding to statistically plausible observations at a smaller L/b time resolution. In the original formulation of the MRC models, the random weights were assumed to be independent and identically distributed. However, for several studies this hypothesis did not appear to be realistic for the observed rainfall series as the distribution of the weights was shown to depend on the space-time scale and rainfall intensity. Since these findings contrast with the scale invariance assumption behind the MRC models and impact on the applicability of these models, it is worth studying their nature. This study explores the possible presence of dependence of the parameters of two discrete MRC models on rainfall intensity and time scale, by analyzing point rainfall series with 5-min time resolution. Taking into account a discrete microcanonical (MC model based on beta distribution and a discrete canonical beta-logstable (BLS, the analysis points out that the relations between the parameters and rainfall intensity across the time scales are detectable and can be modeled by a set of simple functions accounting for the parameter-rainfall intensity relationship, and another set describing the link between the parameters and the time scale. Therefore, MC and BLS models were modified to explicitly account for these relationships and compared with the continuous in scale universal multifractal (CUM model, which is used as a physically based benchmark model. Monte Carlo simulations point out

  12. Phonotactic Constraints: Implications for Models of Oral Reading in Russian

    Science.gov (United States)

    Ulicheva, Anastasia; Coltheart, Max; Saunders, Steven; Perry, Conrad

    2016-01-01

    The present article investigates how phonotactic rules constrain oral reading in the Russian language. The pronunciation of letters in Russian is regular and consistent, but it is subject to substantial phonotactic influence: the position of a phoneme and its phonological context within a word can alter its pronunciation. In Part 1 of the article,…

  13. A Model of Reading Comprehension of Geometry Proof

    Science.gov (United States)

    Yang, Kai-Lin; Lin, Fou-Lai

    2008-01-01

    This study aims to investigate a construct of reading comprehension of geometry proof (RCGP). The research aims to investigate (a) the facets composing RCGP, and (b) the structure of these facets. Firstly, we conceptualize this construct with relevant literature and on the basis of the discrimination between the logical and the epistemic meanings…

  14. Joint Book Reading and Receptive Vocabulary: A Parallel Process Model

    Science.gov (United States)

    Meng, Christine

    2016-01-01

    The purpose of the present study was to understand the reciprocal, bidirectional longitudinal relation between joint book reading and English receptive vocabulary. To address the research goals, a nationally representative sample of Head Start children, the Head Start Family and Child Experiences Survey (2003 cohort), was used for analysis. The…

  15. Mathematical modeling of a continuous alcoholic fermentation process in a two-stage tower reactor cascade with flocculating yeast recycle.

    Science.gov (United States)

    de Oliveira, Samuel Conceição; de Castro, Heizir Ferreira; Visconti, Alexandre Eliseu Stourdze; Giudici, Reinaldo

    2015-03-01

    Experiments of continuous alcoholic fermentation of sugarcane juice with flocculating yeast recycle were conducted in a system of two 0.22-L tower bioreactors in series, operated at a range of dilution rates (D 1 = D 2 = 0.27-0.95 h(-1)), constant recycle ratio (α = F R /F = 4.0) and a sugar concentration in the feed stream (S 0) around 150 g/L. The data obtained in these experimental conditions were used to adjust the parameters of a mathematical model previously developed for the single-stage process. This model considers each of the tower bioreactors as a perfectly mixed continuous reactor and the kinetics of cell growth and product formation takes into account the limitation by substrate and the inhibition by ethanol and biomass, as well as the substrate consumption for cellular maintenance. The model predictions agreed satisfactorily with the measurements taken in both stages of the cascade. The major differences with respect to the kinetic parameters previously estimated for a single-stage system were observed for the maximum specific growth rate, for the inhibition constants of cell growth and for the specific rate of substrate consumption for cell maintenance. Mathematical models were validated and used to simulate alternative operating conditions as well as to analyze the performance of the two-stage process against that of the single-stage process.

  16. Nonlinear Modeling of Azimuth Error for 2D Car Navigation Using Parallel Cascade Identification Augmented with Kalman Filtering

    Directory of Open Access Journals (Sweden)

    Umar Iqbal

    2010-01-01

    Full Text Available Present land vehicle navigation relies mostly on the Global Positioning System (GPS that may be interrupted or deteriorated in urban areas. In order to obtain continuous positioning services in all environments, GPS can be integrated with inertial sensors and vehicle odometer using Kalman filtering (KF. For car navigation, low-cost positioning solutions based on MEMS-based inertial sensors are utilized. To further reduce the cost, a reduced inertial sensor system (RISS consisting of only one gyroscope and speed measurement (obtained from the car odometer is integrated with GPS. The MEMS-based gyroscope measurement deteriorates over time due to different errors like the bias drift. These errors may lead to large azimuth errors and mitigating the azimuth errors requires robust modeling of both linear and nonlinear effects. Therefore, this paper presents a solution based on Parallel Cascade Identification (PCI module that models the azimuth errors and is augmented to KF. The proposed augmented KF-PCI method can handle both linear and nonlinear system errors as the linear parts of the errors are modeled inside the KF and the nonlinear and residual parts of the azimuth errors are modeled by PCI. The performance of this method is examined using road test experiments in a land vehicle.

  17. Disaggregating radar-derived rainfall measurements in East Azarbaijan, Iran, using a spatial random-cascade model

    Science.gov (United States)

    Fouladi Osgouei, Hojjatollah; Zarghami, Mahdi; Ashouri, Hamed

    2016-04-01

    The availability of spatial, high-resolution rainfall data is one of the most essential needs in the study of water resources. These data are extremely valuable in providing flood awareness for dense urban and industrial areas. The first part of this paper applies an optimization-based method to the calibration of radar data based on ground rainfall gauges. Then, the climatological Z-R relationship for the Sahand radar, located in the East Azarbaijan province of Iran, with the help of three adjacent rainfall stations, is obtained. The new climatological Z-R relationship with a power-law form shows acceptable statistical performance, making it suitable for radar-rainfall estimation by the Sahand radar outputs. The second part of the study develops a new heterogeneous random-cascade model for spatially disaggregating the rainfall data resulting from the power-law model. This model is applied to the radar-rainfall image data to disaggregate rainfall data with coverage area of 512 × 512 km2 to a resolution of 32 × 32 km2. Results show that the proposed model has a good ability to disaggregate rainfall data, which may lead to improvement in precipitation forecasting, and ultimately better water-resources management in this arid region, including Urmia Lake.

  18. Disaggregating radar-derived rainfall measurements in East Azarbaijan, Iran, using a spatial random-cascade model

    Science.gov (United States)

    Fouladi Osgouei, Hojjatollah; Zarghami, Mahdi; Ashouri, Hamed

    2017-07-01

    The availability of spatial, high-resolution rainfall data is one of the most essential needs in the study of water resources. These data are extremely valuable in providing flood awareness for dense urban and industrial areas. The first part of this paper applies an optimization-based method to the calibration of radar data based on ground rainfall gauges. Then, the climatological Z-R relationship for the Sahand radar, located in the East Azarbaijan province of Iran, with the help of three adjacent rainfall stations, is obtained. The new climatological Z-R relationship with a power-law form shows acceptable statistical performance, making it suitable for radar-rainfall estimation by the Sahand radar outputs. The second part of the study develops a new heterogeneous random-cascade model for spatially disaggregating the rainfall data resulting from the power-law model. This model is applied to the radar-rainfall image data to disaggregate rainfall data with coverage area of 512 × 512 km2 to a resolution of 32 × 32 km2. Results show that the proposed model has a good ability to disaggregate rainfall data, which may lead to improvement in precipitation forecasting, and ultimately better water-resources management in this arid region, including Urmia Lake.

  19. Impaired oral reading in two atypical dyslexics: a comparison with a computational lexical-analogy model.

    Science.gov (United States)

    Marchand, Yannick; Friedman, Rhonda B

    2005-06-01

    A computational model of reading was developed based upon the notion that the structural relationship between orthography and phonology is of greater importance than the dimension of semantics for the reading aloud of single words. Degradation of this model successfully simulated the reading performance of two patients with atypical acquired dyslexia. The first patient CAV, studied and described in the literature by Warrington in 1981, presented with unusual concrete word dyslexia, i.e., he had a category-specific reading deficit for concrete words compared with abstract words. The second patient BG is a phonological dyslexic who, although displaying a strong concreteness effect (concrete words read better than abstract words), was able to read functors individually perfectly well, a pattern that is rarely if ever seen. The computational model was used to generate a set of words for which it was predicted that BG would show no concreteness effect. The results of BG's reading of these words were consistent with this prediction, thereby providing greater support for the validity of the model. It is concluded that a computational approach that attempts not only to reproduce the core symptoms of the major varieties of acquired dyslexia but also to simulate clinical data from specific patients has much to contribute to the understanding of cognitive deficits and to the design of effective rehabilitation strategies.

  20. Using video self- and peer modeling to facilitate reading fluency in children with learning disabilities.

    Science.gov (United States)

    Decker, Martha M; Buggey, Tom

    2014-01-01

    The authors compared the effects of video self-modeling and video peer modeling on oral reading fluency of elementary students with learning disabilities. A control group was also included to gauge general improvement due to reading instruction and familiarity with researchers. The results indicated that both interventions resulted in improved fluency. Students in both experimental groups improved their reading fluency. Two students in the self-modeling group made substantial and immediate gains beyond any of the other students. Discussion is included that focuses on the importance that positive imagery can have on student performance and the possible applications of both forms of video modeling with students who have had negative experiences in reading.

  1. Cascading Gravity is Ghost Free

    CERN Document Server

    de Rham, Claudia; Tolley, Andrew J

    2010-01-01

    We perform a full perturbative stability analysis of the 6D cascading gravity model in the presence of 3-brane tension. We demonstrate that for sufficiently large tension on the (flat) 3-brane, there are no ghosts at the perturbative level, consistent with results that had previously only been obtained in a specific 5D decoupling limit. These results establish the cascading gravity framework as a consistent infrared modification of gravity.

  2. Reciprocal Effects between Intrinsic Reading Motivation and Reading Competence? A Cross-Lagged Panel Model for Academic Track and Nonacademic Track Students

    Science.gov (United States)

    Schaffner, Ellen; Philipp, Maik; Schiefele, Ulrich

    2016-01-01

    Previous research has demonstrated positive relations between intrinsic reading motivation and reading competence. However, the causal direction of these relations and the moderating role of relevant background variables (e.g., students' achievement level) are not well understood. In the present study, a cross-lagged panel model was applied to…

  3. Current situation for cultivating reflective thinking in English reading instruction--The influence of teaching models

    Institute of Scientific and Technical Information of China (English)

    Meng Qinglan

    2013-01-01

    Reflective thinking plays an essential role in cultivating students’creative ability. It’s essential to cultivate this ability in the process of reading instruction,while the present traditional English teaching models hinder its development. This paper tries to analyze the current situation in cultivating students’reflective thinking in English reading instruction from the traditional teaching models,in the hope of refreshing the teachers’consciousness on their teaching methods.

  4. A Model of Phonological Processing, Language, and Reading for Students with Mild Intellectual Disability

    Science.gov (United States)

    Barker, R. Michael; Sevcik, Rose A.; Morris, Robin D.; Romski, MaryAnn

    2013-01-01

    Little is known about the relationships between phonological processing, language, and reading in children with intellectual disability (ID). We examined the structure of phonological processing in 294 school-aged children with mild ID and the relationships between its components and expressive and receptive language and reading skills using structural equation modeling. Phonological processing consisted of two distinct but correlated latent abilities: phonological awareness and naming speed. Phonological awareness had strong relationships with expressive and receptive language and reading skills. Naming speed had moderate relationships with these variables. Results suggest that children with ID bring the same skills to the task of learning to read as children with typical development, highlighting that phonologically based reading instruction should be considered a viable approach. PMID:24245730

  5. Numerical simulation of turbulent shear flow using a cascade model; Numerische Simulation turbulenter Scherstroemungen mit einem Kaskadenmodell

    Energy Technology Data Exchange (ETDEWEB)

    Niemann, V.

    1998-01-01

    Homogeneous stratified turbulent shear flow was simulated numerically using the cascade model of Eggers and Grossmann (1991). The model is made applicable to homogeneous shear flow by transformation into a coordinate system that moves along with a basic flow with a constant vertical velocity gradient. The author simulated cases of stable thermal stratification with Richardson numbers in the range of 0{<=}Ri{<=}1. The simulation data were evaluated with particular regard to the anisotropic characteristics of the turbulence field. Further, the results are compared with some common equation systems up to second order. (orig.) [Deutsch] Thema der vorliegenden Dissertation ist die numerische Simulation homogener geschichteter turbulenter Scherstroemungen. Grundlage der Simulation ist das von Eggers and Grossmann (1991) entwickelte Kaskadenmodell. Dieses Modell wird durch Transformation in ein Koordinatensystem, das mit einem Grundstrom mit konstantem vertikalen Geschwindigkeitsgradienten mitbewegt wird, auf homogene Scherstroemungen angewendet. Simuliert werden Faelle mit stabiler thermischer Schichtung mit Richardsonzahlen im Bereich von 0{<=}Ri{<=}1. Der Schwerpunkt bei der Auswertung der Simulationsdaten liegt auf der Untersuchung der Anisotropie-Eigenschaften des Turbulenzfeldes. Darueber hinaus wird ein Vergleich mit einigen gaengigen Schliessungsansaetzen bis zur zweiten Ordnung gezogen. (orig.)

  6. Micro-canonical cascade model: Analyzing parameter changes in the future and their influence on disaggregation results

    Science.gov (United States)

    Müller, Hannes; Föt, Annika; Haberlandt, Uwe

    2016-04-01

    Rainfall time series with a high temporal resolution are needed in many hydrological and water resources management fields. Unfortunately, future climate projections are often available only in low temporal resolutions, e.g. daily values. A possible solution is the disaggregation of these time series using information of high-resolution time series of recording stations. Often, the required parameters for the disaggregation process are applied to future climate without any change, because the change is unknown. For this investigation a multiplicative random cascade model is used. The parameters can be estimated directly from high-resolution time series. Here, time series with hourly resolution generated by the ECHAM5-model and dynamically downscaled with the REMO-model (UBA-, BfG- & ENS-realisation) are used for parameter estimation. The parameters are compared between the past (1971-20000), near-term (2021-2050) and long-term future (2071-2100) for temporal resolutions of 1 h and 8 h. Additionally, the parameters of each period are used for the disaggregation of the other two periods. Afterwards the disaggregated time series are analyzed concerning extreme values representation, event specific characteristics (average wet spell duration and amount) and overall time series characteristics (average intensity and fraction of dry spell events). The aim of the investigation is a) to detect and quantify parameter changes and b) to analyze the influence on the disaggregated time series. The investigation area is Lower Saxony, Germany.

  7. Cascading model uncertainty from medium range weather forecasts (10 days through a rainfall-runoff model to flood inundation predictions within the European Flood Forecasting System (EFFS

    Directory of Open Access Journals (Sweden)

    F. Pappenberger

    2005-01-01

    Full Text Available The political pressure on the scientific community to provide medium to long term flood forecasts has increased in the light of recent flooding events in Europe. Such demands can be met by a system consisting of three different model components (weather forecast, rainfall-runoff forecast and flood inundation forecast which are all liable to considerable uncertainty in the input, output and model parameters. Thus, an understanding of cascaded uncertainties is a necessary requirement to provide robust predictions. In this paper, 10-day ahead rainfall forecasts, consisting of one deterministic, one control and 50 ensemble forecasts, are fed into a rainfall-runoff model (LisFlood for which parameter uncertainty is represented by six different parameter sets identified through a Generalised Likelihood Uncertainty Estimation (GLUE analysis and functional hydrograph classification. The runoff of these 52 * 6 realisations form the input to a flood inundation model (LisFlood-FP which acknowledges uncertainty by utilising ten different sets of roughness coefficients identified using the same GLUE methodology. Likelihood measures for each parameter set computed on historical data are used to give uncertain predictions of flow hydrographs as well as spatial inundation extent. This analysis demonstrates that a full uncertainty analysis of such an integrated system is limited mainly by computer power as well as by how well the rainfall predictions represent potential future conditions. However, these restrictions may be overcome or lessened in the future and this paper establishes a computationally feasible methodological approach to the uncertainty cascade problem.

  8. Random cascade model in the limit of infinite integral scale as the exponential of a nonstationary 1/f noise: Application to volatility fluctuations in stock markets

    Science.gov (United States)

    Muzy, Jean-François; Baïle, Rachel; Bacry, Emmanuel

    2013-04-01

    In this paper we propose a new model for volatility fluctuations in financial time series. This model relies on a nonstationary Gaussian process that exhibits aging behavior. It turns out that its properties, over any finite time interval, are very close to continuous cascade models. These latter models are indeed well known to reproduce faithfully the main stylized facts of financial time series. However, it involves a large-scale parameter (the so-called “integral scale” where the cascade is initiated) that is hard to interpret in finance. Moreover, the empirical value of the integral scale is in general deeply correlated to the overall length of the sample. This feature is precisely predicted by our model, which, as illustrated by various examples from daily stock index data, quantitatively reproduces the empirical observations.

  9. Retrofitting Non-Cognitive-Diagnostic Reading Assessment under the Generalized DINA Model Framework

    Science.gov (United States)

    Chen, Huilin; Chen, Jinsong

    2016-01-01

    Cognitive diagnosis models (CDMs) are psychometric models developed mainly to assess examinees' specific strengths and weaknesses in a set of skills or attributes within a domain. By adopting the Generalized-DINA model framework, the recently developed general modeling framework, we attempted to retrofit the PISA reading assessments, a…

  10. AAC Modeling with the iPad during Shared Storybook Reading Pilot Study

    Science.gov (United States)

    Sennott, Samuel C.; Mason, Linda H.

    2016-01-01

    This pilot study describes an intervention package, MODELER for Read and Talk, designed to provide enriched language interaction for children with complex communication needs who require augmentative and alternative communication (AAC). MODELER (Model, Encourage, Respond) includes (a) modeling AAC as you speak, (b) encouraging communication…

  11. Cascades on clique-based graphs

    CERN Document Server

    Hackett, Adam

    2013-01-01

    We present an analytical approach to determining the expected cascade size in a broad range of dynamical models on the class of highly-clustered random graphs introduced in [J. P. Gleeson, Phys. Rev. E 80, 036107 (2009)]. A condition for the existence of global cascades is also derived. Applications of this approach include analyses of percolation, and Watts's model. We show how our techniques can be used to study the effects of in-group bias in cascades on social networks.

  12. Pharmacodynamic/Pharmacogenomic Modeling of Insulin Resistance Genes in Rat Muscle After Methylprednisolone Treatment: Exploring Regulatory Signaling Cascades

    Directory of Open Access Journals (Sweden)

    Zhenling Yao

    2008-01-01

    Full Text Available Corticosteroids (CS effects on insulin resistance related genes in rat skeletal muscle were studied. In our acute study, adrenalectomized (ADX rats were given single doses of 50 mg/kg methylprednisolone (MPL intravenously. In our chronic study, ADX rats were implanted with Alzet mini-pumps giving zero-order release rates of 0.3 mg/kg/h MPL and sacrificed at various times up to 7 days. Total RNA was extracted from gastrocnemius muscles and hybridized to Affymetrix GeneChips. Data mining and literature searches identified 6 insulin resistance related genes which exhibited complex regulatory pathways. Insulin receptor substrate-1 (IRS-1, uncoupling protein 3 (UCP3, pyruvate dehydrogenase kinase isoenzyme 4 (PDK4, fatty acid translocase (FAT and glycerol-3-phosphate acyltransferase (GPAT dynamic profiles were modeled with mutual effects by calculated nuclear drug-receptor complex (DR(N and transcription factors. The oscillatory feature of endothelin-1 (ET-1 expression was depicted by a negative feedback loop. These integrated models provide test- able quantitative hypotheses for these regulatory cascades.

  13. A domain model of a clinical reading center - Design and implementation.

    Science.gov (United States)

    Lotz, Gunnar; Peters, Tobias; Zrenner, Eberhart; Wilke, Robert

    2010-01-01

    In clinical trials huge amounts of raw data are generated. Often these data are submitted to reading centers for being analyzed by experts of that particular type of examination. Although the installment of a reading center can raise the overall quality, they also introduce additional complexity to the management and conduction of a clinical trial. Software can help to handle this complexity. Domain-driven-design is one concept to tackle software development in such complex domains. Here we present our domain model for a clinical reading center, as well as its actual implementation utilizing the Nuxeo enterprise content management system.

  14. Do current connectionist learning models account for reading development in different languages?

    Science.gov (United States)

    Hutzler, Florian; Ziegler, Johannes C; Perry, Conrad; Wimmer, Heinz; Zorzi, Marco

    2004-04-01

    Learning to read a relatively irregular orthography, such as English, is harder and takes longer than learning to read a relatively regular orthography, such as German. At the end of grade 1, the difference in reading performance on a simple set of words and nonwords is quite dramatic. Whereas children using regular orthographies are already close to ceiling, English children read only about 40% of the words and nonwords correctly. It takes almost 4 years for English children to come close to the reading level of their German peers. In the present study, we investigated to what extent recent connectionist learning models are capable of simulating this cross-language learning rate effect as measured by nonword decoding accuracy. We implemented German and English versions of two major connectionist reading models, Plaut et al.'s (Plaut, D. C., McClelland, J. L., Seidenberg, M. S., & Patterson, K. (1996). Understanding normal and impaired word reading: computational principles in quasi-regular domains. Psychological Review, 103, 56-115) parallel distributed model and Zorzi et al.'s (Zorzi, M., Houghton, G., & Butterworth, B. (1998a). Two routes or one in reading aloud? A connectionist dual-process model. Journal of Experimental Psychology: Human Perception and Performance, 24, 1131-1161); two-layer associative network. While both models predicted an overall advantage for the more regular orthography (i.e. German over English), they failed to predict that the difference between children learning to read regular versus irregular orthographies is larger earlier on. Further investigations showed that the two-layer network could be brought to simulate the cross-language learning rate effect when cross-language differences in teaching methods (phonics versus whole-word approach) were taken into account. The present work thus shows that in order to adequately capture the pattern of reading acquisition displayed by children, current connectionist models must not only be

  15. Deriving global flood hazard maps of fluvial floods through a physical model cascade

    OpenAIRE

    Pappenberger, F.; E. Dutra; Wetterhall, F.; Cloke, H

    2012-01-01

    Global flood hazard maps can be used in the assessment of flood risk in a number of different applications, including (re)insurance and large scale flood preparedness. Such global hazard maps can be generated using large scale physically based models of rainfall-runoff and river routing, when used in conjunction with a number of post-processing methods. In this study, the European Centre for Medium Range Weather Forecasts (ECMWF) land surface model is coupled to ERA-Interim reanalysis meteoro...

  16. MODELING COLLISIONAL CASCADES IN DEBRIS DISKS: STEEP DUST-SIZE DISTRIBUTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Gaspar, Andras; Psaltis, Dimitrios; Rieke, George H.; Oezel, Feryal, E-mail: agaspar@as.arizona.edu, E-mail: dpsaltis@as.arizona.edu, E-mail: grieke@as.arizona.edu, E-mail: fozel@as.arizona.edu [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)

    2012-07-20

    We explore the evolution of the mass distribution of dust in collision-dominated debris disks, using the collisional code introduced in our previous paper. We analyze the equilibrium distribution and its dependence on model parameters by evolving over 100 models to 10 Gyr. With our numerical models, we confirm that systems reach collisional equilibrium with a mass distribution that is steeper than the traditional solution by Dohnanyi. Our model yields a quasi-steady-state slope of n(m) {approx} m{sup -1.88} [n(a) {approx} a{sup -3.65}] as a robust solution for a wide range of possible model parameters. We also show that a simple power-law function can be an appropriate approximation for the mass distribution of particles in certain regimes. The steeper solution has observable effects in the submillimeter and millimeter wavelength regimes of the electromagnetic spectrum. We assemble data for nine debris disks that have been observed at these wavelengths and, using a simplified absorption efficiency model, show that the predicted slope of the particle-mass distribution generates spectral energy distributions that are in agreement with the observed ones.

  17. The Use of Repeated Reading with Computer Modeling to Promote Reading Fluency with Students Who Have Physical Disabilities

    Science.gov (United States)

    Coleman, Mari Beth; Heller, Kathryn Wolff

    2010-01-01

    The ability to read fluently is a critical skill that allows the reader to concentrate on the meaning of the text. It also can contribute to a successful reading experience. However, students with physical disabilities may have difficulty reading fluently due to any number of functional, psychosocial, or environmental factors that can accompany a…

  18. Energy cascades in the upper ocean

    Institute of Scientific and Technical Information of China (English)

    Ray Q.Lin; Scott Chubb

    2006-01-01

    Wave-wave interactions cause energy cascades. These are the most important processes in the upper ocean because they govern wave-growth and dissipation. Through indirect cascades, wave energy is transferred from higher frequencies to lower frequencies, leading to wave growth. In direct cascades, energy is transferred from lower frequencies to the higher frequencies, which causes waves to break, and dissipation of wave energy. However, the evolution and origin of energy cascade processes are still not fully understood. In particular, for example, results from a recent theory (Kalmykov, 1998) suggest that the class I wave-wave interactions (defined by situations involving 4-, 6-, 8-, etc, even numbers of resonantly interacting waves) cause indirect cascades, and Class II wave-wave interactions (involving, 5-, 7-, 9-, etc, .., odd numbers of waves) cause direct cascades. In contrast to this theory, our model results indicate the 4-wave interactions can cause significant transfer of wave energy through both direct and indirect cascades. In most situations, 4-wave interactions provide the major source of energy transfer for both direct cascades and indirect cascades, except when the wave steepness is larger than 0.28. Our model results agree well with wave measurements, obtained using field buoy data (for example, Lin and Lin, 2002). In particular, in these observations, asymmetrical wave-wave interactions were studied. They found that direct and indirect cascades both are mainly due to the 4-wave interactions when wave steepness is less than 0.3.

  19. Application of Three Cognitive Diagnosis Models to ESL Reading and Listening Assessments

    Science.gov (United States)

    Lee, Yong-Won; Sawaki, Yasuyo

    2009-01-01

    The present study investigated the functioning of three psychometric models for cognitive diagnosis--the general diagnostic model, the fusion model, and latent class analysis--when applied to large-scale English as a second language listening and reading comprehension assessments. Data used in this study were scored item responses and incidence…

  20. Beyond Market Models and Resistance: Organizations as a Middle Layer in the History of Reading

    Science.gov (United States)

    Pawley, Christine

    2009-01-01

    Two theoretical models dominate discussion of research methods in the history of reading: "market" models such as Robert Darnton's communications circuit and "resistance" models such as those that draw on Michel de Certeau's concept of poaching. This article suggests that both make important contributions but also have limitations, especially when…

  1. Model test of the tunnel subjected to high water pressure in Jinping Second Cascade Hydropower Station,China

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In the area with high groundwater pressure,grout curtain is often adopted to reduce the water pressure on tunnel lining.A series of model tests for the diversion tunnel of the Jinping Second Cascade Hydropower Station,China,is designed to study the effect of grout curtain.The impact of the thickness of grout curtain,permeability of grout curtain,internal water pressure and drainage inflow on the distribution of water pressure are discussed.The results indicates that under un-drained condition,water pressure is equal to hydrostatic one no matter grout curtain is selected or not,water pressure under drained condition is far less than that of un-drained condition,drainage in tunnel can reduce tunnel water pressure effectively.For same inflow,both increasing of thickness and decrease of hydraulic conductivity of grout curtain can reduce water pressure effectively.For the same water pressure,the smaller inflow of grout curtain,the less volume of water to be discharged.The impact of hydraulic conductivity of grout curtain is more obvious than that of thickness.With increasing of internal water pressure,the water pressure of grout curtain increases too,and the water pressure increases nearly linearly.The proposed thickness of grout curtain for the diversion tunnels is 16 m.

  2. A comprehensive model of gain recovery due to unipolar electron transport after a short optical pulse in quantum cascade lasers

    Science.gov (United States)

    Jamali Mahabadi, S. E.; Hu, Yue; Talukder, Muhammad Anisuzzaman; Carruthers, Thomas F.; Menyuk, Curtis R.

    2016-10-01

    We have developed a comprehensive model of gain recovery due to unipolar electron transport after a short optical pulse in quantum cascade lasers (QCLs) that takes into account all the participating energy levels, including the continuum, in a device. This work takes into account the incoherent scattering of electrons from one energy level to another and quantum coherent tunneling from an injector level to an active region level or vice versa. In contrast to the prior work that only considered transitions to and from a limited number of bound levels, this work include transitions between all bound levels and between the bound energy levels and the continuum. We simulated an experiment of S. Liu et al., in which 438-pJ femtosecond optical pulses at the device's lasing wavelength were injected into an I n0.653 Ga0.348 As/In0.310 Al0.690 As QCL structure; we found that approximately 1% of the electrons in the bound energy levels will be excited into the continuum by a pulse and that the probability that these electrons will be scattered back into bound energy levels is negligible, ˜10-4 . The gain recovery that is predicted is not consistent with the experiments, indicating that one or more phenomena besides unipolar electron transport in response to a short optical pulse play an important role in the observed gain recovery.

  3. Development of a Higher Fidelity Model for the Cascade Distillation Subsystem (CDS)

    Science.gov (United States)

    Perry, Bruce; Anderson, Molly

    2014-01-01

    Significant improvements have been made to the ACM model of the CDS, enabling accurate predictions of dynamic operations with fewer assumptions. The model has been utilized to predict how CDS performance would be impacted by changing operating parameters, revealing performance trade-offs and possibilities for improvement. CDS efficiency is driven by the THP coefficient of performance, which in turn is dependent on heat transfer within the system. Based on the remaining limitations of the simulation, priorities for further model development include: center dot Relaxing the assumption of total condensation center dot Incorporating dynamic simulation capability for the buildup of dissolved inert gasses in condensers center dot Examining CDS operation with more complex feeds center dot Extending heat transfer analysis to all surfaces

  4. Modeling reading vocabulary learning in deaf children in bilingual education programs.

    Science.gov (United States)

    Hermans, Daan; Knoors, Harry; Ormel, Ellen; Verhoeven, Ludo

    2008-01-01

    The acquisition of reading vocabulary is one of the major challenges for deaf children in bilingual education programs. Deaf children have to acquire a written lexicon that can effectively be used in reading. In this paper, we present a developmental model that describes reading vocabulary acquisition of deaf children in bilingual education programs. The model is inspired by Jiang's model of vocabulary development in a second language (N. Jiang, 2000, 2004a) and the hierarchical model of lexical representation and processing in bilinguals (J. F. Kroll & E. Stewart, 1988). We argue that lexical development in the written language often fossilizes and that many words deaf readers acquire will not reach the final stage of lexical development. We argue that this feature is consistent with many findings reported in the literature. Finally, we discuss the pedagogical implications of the model.

  5. Leveraging Structural Characteristics of Interdependent Networks to Model Non-Linear Cascading Risks

    Science.gov (United States)

    2013-04-01

    jung.sourceforge.net/), and so forth. State of the program in our decision-theoretic DEC- MDP model captures the critical information at a specific point in time...the performance factor for 5/10 years time span for all MDAPs, based on a composite metric (it may include the breach factors, %PAUC, funding delta...features to describe the state space of the program within the DEC- MDP model. The following is the list of features of interest:  Feature 1

  6. A Longitudinal Study of Reading Comprehension Achievement from Grades 3 to 10: Investigating Models of Stability, Cumulative Growth, and Compensation

    Science.gov (United States)

    Kwiatkowska-White, Bozena; Kirby, John R.; Lee, Elizabeth A.

    2016-01-01

    This longitudinal study of 78 Canadian English-speaking students examined the applicability of the stability, cumulative, and compensatory models in reading comprehension development. Archival government-mandated assessments of reading comprehension at Grades 3, 6, and 10, and the Canadian Test of Basic Skills measure of reading comprehension…

  7. A Longitudinal Study of Reading Comprehension Achievement from Grades 3 to 10: Investigating Models of Stability, Cumulative Growth, and Compensation

    Science.gov (United States)

    Kwiatkowska-White, Bozena; Kirby, John R.; Lee, Elizabeth A.

    2016-01-01

    This longitudinal study of 78 Canadian English-speaking students examined the applicability of the stability, cumulative, and compensatory models in reading comprehension development. Archival government-mandated assessments of reading comprehension at Grades 3, 6, and 10, and the Canadian Test of Basic Skills measure of reading comprehension…

  8. Modeling of mid-infrared quantum cascade lasers: The role of temperature and operating field strength on the laser performance

    Science.gov (United States)

    Yousefvand, Hossein Reza

    2017-07-01

    In this paper a self-consistent numerical approach to study the temperature and bias dependent characteristics of mid-infrared (mid-IR) quantum cascade lasers (QCLs) is presented which integrates a number of quantum mechanical models. The field-dependent laser parameters including the nonradiative scattering times, the detuning and energy levels, the escape activation energy, the backfilling excitation energy and dipole moment of the optical transition are calculated for a wide range of applied electric fields by a self-consistent solution of Schrodinger-Poisson equations. A detailed analysis of performance of the obtained structure is carried out within a self-consistent solution of the subband population rate equations coupled with carrier coherent transport equations through the sequential resonant tunneling, by taking into account the temperature and bias dependency of the relevant parameters. Furthermore, the heat transfer equation is included in order to calculate the carrier temperature inside the active region levels. This leads to a compact predictive model to analyze the temperature and electric field dependent characteristics of the mid-IR QCLs such as the light-current (L-I), electric field-current (F-I) and core temperature-electric field (T-F) curves. For a typical mid-IR QCL, a good agreement was found between the simulated temperature-dependent L-I characteristic and experimental data, which confirms validity of the model. It is found that the main characteristics of the device such as output power and turn-on delay time are degraded by interplay between the temperature and Stark effects.

  9. Information cascade on networks

    CERN Document Server

    Hisakado, Masato

    2015-01-01

    In this paper, we discuss a voting model by considering three different kinds of networks: a random graph, the Barab\\'{a}si-Albert(BA) model, and a fitness model. A voting model represents the way in which public perceptions are conveyed to voters. Our voting model is constructed by using two types of voters--herders and independents--and two candidates. Independents conduct voting based on their fundamental values; on the other hand, herders base their voting on the number of previous votes. Hence, herders vote for the majority candidates and obtain information relating to previous votes from their networks. We discussed the difference between the phases on which the networks depend. Two kinds of phase transitions, an information cascade transition and a super-normal transition, were identified. The first of these is a transition between a state in which most voters make the correct choices and a state in which most of them are wrong. The second is a transition of convergence speed. The information cascade t...

  10. Laos Organization Name Using Cascaded Model Based on SVM and CRF

    Directory of Open Access Journals (Sweden)

    Duan Shaopeng

    2017-01-01

    Full Text Available According to the characteristics of Laos organization name, this paper proposes a two layer model based on conditional random field (CRF and support vector machine (SVM for Laos organization name recognition. A layer of model uses CRF to recognition simple organization name, and the result is used to support the decision of the second level. Based on the driving method, the second layer uses SVM and CRF to recognition the complicated organization name. Finally, the results of the two levels are combined, And by a subsequent treatment to correct results of low confidence recognition. The results show that this approach based on SVM and CRF is efficient in recognizing organization name through open test for real linguistics, and the recalling rate achieve 80. 83%and the precision rate achieves 82. 75%.

  11. Modeling and hazard mapping of complex cascading mass movement processes: the case of glacier lake 513, Carhuaz, Peru

    Science.gov (United States)

    Schneider, Demian; Huggel, Christian; García, Javier; Ludeña, Sebastian; Cochachin, Alejo

    2013-04-01

    that complex cascades of mass movement processes can realistically be modeled using different models and model parameters. The method to semi-automatically produce hazard maps is promising and should be applied in other case studies. Verification of model based results in the field remains an important requirement. Results from this study are important for the GLOF early warning system that is currently in an implementation phase, and for risk reduction efforts in general.

  12. A Dual Coding Theoretical Model of Decoding in Reading: Subsuming the LaBerge and Samuels Model

    Science.gov (United States)

    Sadoski, Mark; McTigue, Erin M.; Paivio, Allan

    2012-01-01

    In this article we present a detailed Dual Coding Theory (DCT) model of decoding. The DCT model reinterprets and subsumes The LaBerge and Samuels (1974) model of the reading process which has served well to account for decoding behaviors and the processes that underlie them. However, the LaBerge and Samuels model has had little to say about…

  13. Human Brain Networks: Spiking Neuron Models, Multistability, Synchronization, Thermodynamics, Maximum Entropy Production, and Anesthetic Cascade Mechanisms

    Directory of Open Access Journals (Sweden)

    Wassim M. Haddad

    2014-07-01

    Full Text Available Advances in neuroscience have been closely linked to mathematical modeling beginning with the integrate-and-fire model of Lapicque and proceeding through the modeling of the action potential by Hodgkin and Huxley to the current era. The fundamental building block of the central nervous system, the neuron, may be thought of as a dynamic element that is “excitable”, and can generate a pulse or spike whenever the electrochemical potential across the cell membrane of the neuron exceeds a threshold. A key application of nonlinear dynamical systems theory to the neurosciences is to study phenomena of the central nervous system that exhibit nearly discontinuous transitions between macroscopic states. A very challenging and clinically important problem exhibiting this phenomenon is the induction of general anesthesia. In any specific patient, the transition from consciousness to unconsciousness as the concentration of anesthetic drugs increases is very sharp, resembling a thermodynamic phase transition. This paper focuses on multistability theory for continuous and discontinuous dynamical systems having a set of multiple isolated equilibria and/or a continuum of equilibria. Multistability is the property whereby the solutions of a dynamical system can alternate between two or more mutually exclusive Lyapunov stable and convergent equilibrium states under asymptotically slowly changing inputs or system parameters. In this paper, we extend the theory of multistability to continuous, discontinuous, and stochastic nonlinear dynamical systems. In particular, Lyapunov-based tests for multistability and synchronization of dynamical systems with continuously differentiable and absolutely continuous flows are established. The results are then applied to excitatory and inhibitory biological neuronal networks to explain the underlying mechanism of action for anesthesia and consciousness from a multistable dynamical system perspective, thereby providing a

  14. Does Reading Cause Later Intelligence? Accounting for Stability in Models of Change.

    Science.gov (United States)

    Bailey, Drew H; Littlefield, Andrew K

    2016-11-08

    This study reanalyzes data presented by Ritchie, Bates, and Plomin (2015) who used a cross-lagged monozygotic twin differences design to test whether reading ability caused changes in intelligence. The authors used data from a sample of 1,890 monozygotic twin pairs tested on reading ability and intelligence at five occasions between the ages of 7 and 16, regressing twin differences in intelligence on twin differences in prior intelligence and twin differences in prior reading ability. Results from a state-trait model suggest that reported effects of reading ability on later intelligence may be artifacts of previously uncontrolled factors, both environmental in origin and stable during this developmental period, influencing both constructs throughout development. Implications for cognitive developmental theory and methods are discussed. © 2016 The Authors. Child Development © 2016 Society for Research in Child Development, Inc.

  15. Modelling cascading and erosional processes for glacial lake outburst floods in the Quillcay catchment, Huaraz, Cordillera Blanca, Peru

    Science.gov (United States)

    Baer, Patrick; Huggel, Christian; Frey, Holger; Chisolm, Rachel; McKinney, Daene; McArdell, Brian; Portocarrero, Cesar; Cochachin, Alejo

    2016-04-01

    Huaraz as the largest city in Cordillera Blanca has faced a major disaster in 1941, when an outburst flood from Lake Palcacocha killed several thousand people and caused widespread destruction. Recent studies on glacial lake outburst flood (GLOF) modelling and early warning systems focussed on Lake Palcacocha which has regrown after the 1941 event, from a volume of half a million m3 in 1974 to a total volume of more than 17 million m3 today. However, little research has been conducted so far concerning the situation of other lakes in the Quillcay catchment, namely Lake Tullparaju (12 mill. m3) and Cuchillacocha (2.5 mill. m3), which both also pose a threat to the city of Huaraz. In this study, we modelled the cascading processes at Lake Tullparaju and Lake Cuchillacocha including rock/ice avalanches, flood wave propagation in the lake and the resulting outburst flood and debris flows. We used the 2D model RAMMS to simulate ice avalanches. Model output was used as input for analytical 2D and 3D calculations of impact waves in the lakes that allowed us to estimate dam overtopping wave height. Since the dimension of the hanging glaciers above all three lakes is comparable, the scenarios in this study have been defined similar to the previous study at Lake Palcacocha. The flow propagation model included sediment entrainment in the steeper parts of the catchment, adding up to 50% to the initial flow volume. The results for total travel time as well as for inundated areas and flow depth and velocity in the city of Huaraz are comparable to the previous studies at Lake Palcacocha. This underlines the importance of considering also these lakes within an integral hazard analysis for the city of Huaraz. A main challenge for modelling GLOFs in the Quillcay catchment using RAMMS is the long runout distance of over 22 km combined with the very low slope gradient of the river. Further studies could improve the process understanding and could focus on more detailed investigations

  16. Autoregressive cascades on random networks

    Science.gov (United States)

    Iyer, Srikanth K.; Vaze, Rahul; Narasimha, Dheeraj

    2016-04-01

    A network cascade model that captures many real-life correlated node failures in large networks via load redistribution is studied. The considered model is well suited for networks where physical quantities are transmitted, e.g., studying large scale outages in electrical power grids, gridlocks in road networks, and connectivity breakdown in communication networks, etc. For this model, a phase transition is established, i.e., existence of critical thresholds above or below which a small number of node failures lead to a global cascade of network failures or not. Theoretical bounds are obtained for the phase transition on the critical capacity parameter that determines the threshold above and below which cascade appears or disappears, respectively, that are shown to closely follow numerical simulation results.

  17. A Reinforcement Learning Model Using Neural Networks for Music Sight Reading Learning Problem

    CERN Document Server

    Yahya, Keyvan

    2010-01-01

    Music Sight Reading is a complex process that when it is occurred in the brain, some learning attributes would be emerged. Besides giving a model based on actor-critic method in the Reinforcement Learning, the agent is considered to have a neural network structure. We studied on where the sight reading process is happened and also a serious problem which is how the synaptic weights would be adjusted through the learning process. The model we offer here is a computational model on which an updated weights equation to fixing the weights is accompanied too.

  18. Deriving global flood hazard maps of fluvial floods through a physical model cascade

    Science.gov (United States)

    Pappenberger, Florian; Dutra, Emanuel; Wetterhall, Fredrik; Cloke, Hannah L.

    2013-04-01

    Global flood hazard maps can be used in the assessment of flood risk in a number of different applications, including (re)insurance and large scale flood preparedness. Such global hazard maps can be generated using large scale physically based models of rainfall-runoff and river routing, when used in conjunction with a number of post-processing methods. In this study, the European Centre for Medium Range Weather Forecasts (ECMWF) land surface model is coupled to ERA-Interim reanalysis meteorological forcing data, and resultant runoff is passed to a river routing algorithm which simulates floodplains and flood flow across the global land area. The global hazard map is based on a 30 yr (1979-2010) simulation period. A Gumbel distribution is fitted to the annual maxima flows to derive a number of flood return periods. The return periods are calculated initially for a 25 × 25 km grid, which is then reprojected onto a 1 × 1 km grid to derive maps of higher resolution and estimate flooded fractional area for the individual 25 × 25 km cells. Several global and regional maps of flood return periods ranging from 2 to 500 yr are presented. The results compare reasonably to a benchmark data set of global flood hazard. The developed methodology can be applied to other datasets on a global or regional scale.

  19. Deriving global flood hazard maps of fluvial floods through a physical model cascade

    Directory of Open Access Journals (Sweden)

    F. Pappenberger

    2012-11-01

    Full Text Available Global flood hazard maps can be used in the assessment of flood risk in a number of different applications, including (reinsurance and large scale flood preparedness. Such global hazard maps can be generated using large scale physically based models of rainfall-runoff and river routing, when used in conjunction with a number of post-processing methods. In this study, the European Centre for Medium Range Weather Forecasts (ECMWF land surface model is coupled to ERA-Interim reanalysis meteorological forcing data, and resultant runoff is passed to a river routing algorithm which simulates floodplains and flood flow across the global land area. The global hazard map is based on a 30 yr (1979–2010 simulation period. A Gumbel distribution is fitted to the annual maxima flows to derive a number of flood return periods. The return periods are calculated initially for a 25 × 25 km grid, which is then reprojected onto a 1 × 1 km grid to derive maps of higher resolution and estimate flooded fractional area for the individual 25 × 25 km cells. Several global and regional maps of flood return periods ranging from 2 to 500 yr are presented. The results compare reasonably to a benchmark data set of global flood hazard. The developed methodology can be applied to other datasets on a global or regional scale.

  20. Applicability of the Compensatory Encoding Model in Foreign Language Reading: An Investigation with Chinese College English Language Learners.

    Science.gov (United States)

    Han, Feifei

    2017-01-01

    While some first language (L1) reading models suggest that inefficient word recognition and small working memory tend to inhibit higher-level comprehension processes; the Compensatory Encoding Model maintains that slow word recognition and small working memory do not normally hinder reading comprehension, as readers are able to operate metacognitive strategies to compensate for inefficient word recognition and working memory limitation as long as readers process a reading task without time constraint. Although empirical evidence is accumulated for support of the Compensatory Encoding Model in L1 reading, there is lack of research for testing of the Compensatory Encoding Model in foreign language (FL) reading. This research empirically tested the Compensatory Encoding Model in English reading among Chinese college English language learners (ELLs). Two studies were conducted. Study one focused on testing whether reading condition varying time affects the relationship between word recognition, working memory, and reading comprehension. Students were tested on a computerized English word recognition test, a computerized Operation Span task, and reading comprehension in time constraint and non-time constraint reading. The correlation and regression analyses showed that the strength of association was much stronger between word recognition, working memory, and reading comprehension in time constraint than that in non-time constraint reading condition. Study two examined whether FL readers were able to operate metacognitive reading strategies as a compensatory way of reading comprehension for inefficient word recognition and working memory limitation in non-time constraint reading. The participants were tested on the same computerized English word recognition test and Operation Span test. They were required to think aloud while reading and to complete the comprehension questions. The think-aloud protocols were coded for concurrent use of reading strategies, classified

  1. Precursors of adolescent substance use from early childhood and early adolescence: testing a developmental cascade model.

    Science.gov (United States)

    Sitnick, Stephanie L; Shaw, Daniel S; Hyde, Luke W

    2014-02-01

    This study examined developmentally salient risk and protective factors of adolescent substance use assessed during early childhood and early adolescence using a sample of 310 low-income boys. Child problem behavior and proximal family risk and protective factors (i.e., parenting and maternal depression) during early childhood, as well as child and family factors and peer deviant behavior during adolescence, were explored as potential precursors to later substance use during adolescence using structural equation modeling. Results revealed that early childhood risk and protective factors (i.e., child externalizing problems, mothers' depressive symptomatology, and nurturant parenting) were indirectly related to substance use at the age of 17 via risk and protective factors during early and middle adolescence (i.e., parental knowledge and externalizing problems). The implications of these findings for early prevention and intervention are discussed.

  2. Calibration and field application of a Sierra Model 235 cascade impactor

    Energy Technology Data Exchange (ETDEWEB)

    Knuth, R.H.

    1984-06-01

    A Sierra Model 235 slotted impactor was used to measure the particle size distribution of ore dust in uranium concentrating mills. The impactor was calibrated at a flow rate of 0.21 m/sup 3//min, using solid monodisperse particles of methylene blue and an impaction surface of Whatman number41 filter paper soaked in mineral oil. The reduction from the impactor's design flow rate of 1.13 m/sup 3//min (40 cfm) to 0.21 m/sup 3//min (7.5 cfm), a necessary adjustment because of the anticipated large particle sizes of ore dust, increased the stage cut-off diameters by an average factor of 2.3. Evaluation of field test results revealed that the underestimation of mass median diameters, often caused by the rebound and reentrainment of solid particles from dry impaction surfaces, was virtually eliminated by using the oiled Whatman number41 impaction surface.

  3. The equal load-sharing model of cascade failures in power grids

    CERN Document Server

    Scala, Antonio

    2015-01-01

    Electric power-systems are one of the most important critical infrastructures. In recent years, they have been exposed to extreme stress due to the increasing demand, the introduction of distributed renewable energy sources, and the development of extensive interconnections. We investigate the phenomenon of abrupt breakdown of an electric power-system under two scenarios: load growth (mimicking the ever-increasing customer demand) and power fluctuations (mimicking the effects of renewable sources). Our results indicate that increasing the system size causes breakdowns to become more abrupt; in fact, mapping the system to a solvable statistical-physics model indicates the occurrence of a first order transition in the large size limit. Such an enhancement for the systemic risk failures (black-outs) with increasing network size is an effect that should be considered in the current projects aiming to integrate national power-grids into "super-grids".

  4. The equal load-sharing model of cascade failures in power grids

    Science.gov (United States)

    Scala, Antonio; De Sanctis Lucentini, Pier Giorgio

    2016-11-01

    Electric power-systems are one of the most important critical infrastructures. In recent years, they have been exposed to extreme stress due to the increasing power demand, the introduction of distributed renewable energy sources, and the development of extensive interconnections. We investigate the phenomenon of abrupt breakdown of an electric power-system under two scenarios: load growth (mimicking the ever-increasing customer demand) and power fluctuations (mimicking the effects of renewable sources). Our results indicate that increasing the system size causes breakdowns to become more abrupt; in fact, mapping the system to a solvable statistical-physics model indicates the occurrence of a first order transition in the large size limit. Such an enhancement for the systemic risk failures (black-outs) with increasing network size is an effect that should be considered in the current projects aiming to integrate national power-grids into "super-grids".

  5. Coarse graining approach to First principles modeling of radiation cascade in large Fe super-cells

    Science.gov (United States)

    Odbadrakh, Khorgolkhuu; Nicholson, Don; Rusanu, Aurelian; Wang, Yang; Stoller, Roger; Zhang, Xiaoguang; Stocks, George

    2012-02-01

    First principles techniques employed to understand systems at an atomistic level are not practical for large systems consisting of millions of atoms. We present an efficient coarse graining approach to bridge the first principles calculations of local electronic properties to classical Molecular Dynamics (MD) simulations of large structures. Local atomic magnetic moments in crystalline Fe are perturbed by radiation generated defects. The effects are most pronounced near the defect core and decay with distance. We develop a coarse grained technique based on the Locally Self-consistent Multiple Scattering (LSMS) method that exploits the near-sightedness of the electron Green function. The atomic positions were determined by MD with an embedded atom force field. The local moments in the neighborhood of the defect cores are calculated with first-principles based on full local structure information. Atoms in the rest of the system are modeled by representative atoms with approximated properties. This work was supported by the Center for Defect Physics, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences.

  6. Developmental Relations between Vocabulary Knowledge and Reading Comprehension: A Latent Change Score Modeling Study

    Science.gov (United States)

    Quinn, Jamie M.; Wagner, Richard K.; Petscher, Yaacov; Lopez, Danielle

    2015-01-01

    The present study followed a sample of first-grade (N = 316, M[subscript age] = 7.05 at first test) through fourth-grade students to evaluate dynamic developmental relations between vocabulary knowledge and reading comprehension. Using latent change score modeling, competing models were fit to the repeated measurements of vocabulary knowledge and…

  7. Influencing Children's Self-Efficacy and Self-Regulation of Reading and Writing through Modeling

    Science.gov (United States)

    Schunk, Dale H.; Zimmerman, Barry J.

    2007-01-01

    According to Bandura's social cognitive theory, self-efficacy and self-regulation are key processes that affect students' learning and achievement. This article discusses students' reading and writing performances using Zimmerman's four-phase social cognitive model of the development of self-regulatory competence. Modeling is an effective means of…

  8. Applying Unidimensional and Multidimensional Item Response Theory Models in Testlet-Based Reading Assessment

    Science.gov (United States)

    Min, Shangchao; He, Lianzhen

    2014-01-01

    This study examined the relative effectiveness of the multidimensional bi-factor model and multidimensional testlet response theory (TRT) model in accommodating local dependence in testlet-based reading assessment with both dichotomously and polytomously scored items. The data used were 14,089 test-takers' item-level responses to the testlet-based…

  9. The Effect of Flipped Model of Instruction on EFL Learners' Reading Comprehension: Learners' Attitudes in Focus

    Science.gov (United States)

    Karimi, Mehrnoosh; Hamzavi, Raouf

    2017-01-01

    The present study aimed at investigating the effect of flipped model of instruction on EFL learners' reading comprehension ability. Moreover, this study aimed at identifying EFL students' attitudes toward flipped model of instruction. To this end, 60 EFL learners studying at an accredited private language institute in Isfahan were first…

  10. Developmental Relations between Vocabulary Knowledge and Reading Comprehension: A Latent Change Score Modeling Study

    Science.gov (United States)

    Quinn, Jamie M.; Wagner, Richard K.; Petscher, Yaacov; Lopez, Danielle

    2015-01-01

    The present study followed a sample of first-grade (N = 316, M[subscript age] = 7.05 at first test) through fourth-grade students to evaluate dynamic developmental relations between vocabulary knowledge and reading comprehension. Using latent change score modeling, competing models were fit to the repeated measurements of vocabulary knowledge and…

  11. A Blended Learning Model for Teaching Reading in English as a Foreign Language

    Science.gov (United States)

    Karkour, Islam

    2014-01-01

    The aim of this paper is to describe a blended learning model to be used in Egyptian schools when teaching reading classes in English as a foreign language. This paper is divided into three parts. The first part outlines the Egyptian context and describes the target learners. The second part describes the suggested blended learning model, which is…

  12. Unsteady transonic flow over cascade blades

    Science.gov (United States)

    Surampudi, S. P.; Adamczyk, J. J.

    1986-01-01

    An attempt is made to develop an efficient staggered cascade blade unsteady aerodynamics model for the neighborhood of March 1, representing the blade row by a rectilinear two-dimensional cascade of thin, flat plate airfoils. The equations of motion are derived on the basis of linearized transonic small perturbation theory, and an analytical solution is obtained by means of the Wiener-Hopf procedure. Making use of the transonic similarity law, the results obtained are compared with those of other linearized cascade analyses. A parametric study is conducted to find the effects of reduced frequency, stagger angle, solidity, and the location of the pitching axis on cascade stability.

  13. Trophic cascades of bottom-up and top-down forcing on nutrients and plankton in the Kattegat, evaluated by modelling

    Science.gov (United States)

    Petersen, Marcell Elo; Maar, Marie; Larsen, Janus; Møller, Eva Friis; Hansen, Per Juel

    2017-05-01

    The aim of the study was to investigate the relative importance of bottom-up and top-down forcing on trophic cascades in the pelagic food-web and the implications for water quality indicators (summer phytoplankton biomass and winter nutrients) in relation to management. The 3D ecological model ERGOM was validated and applied in a local set-up of the Kattegat, Denmark, using the off-line Flexsem framework. The model scenarios were conducted by changing the forcing by ± 20% of nutrient inputs (bottom-up) and mesozooplankton mortality (top-down), and both types of forcing combined. The model results showed that cascading effects operated differently depending on the forcing type. In the single-forcing bottom-up scenarios, the cascade directions were in the same direction as the forcing. For scenarios involving top-down, there was a skipped-level-transmission in the trophic responses that was either attenuated or amplified at different trophic levels. On a seasonal scale, bottom-up forcing showed strongest response during winter-spring for DIN and Chl a concentrations, whereas top-down forcing had the highest cascade strength during summer for Chl a concentrations and microzooplankton biomass. On annual basis, the system was more bottom-up than top-down controlled. Microzooplankton was found to play an important role in the pelagic food web as mediator of nutrient and energy fluxes. This study demonstrated that the best scenario for improved water quality was a combined reduction in nutrient input and mesozooplankton mortality calling for the need of an integrated management of marine areas exploited by human activities.

  14. Study on Cascading Failures′Model of Edge in Coupled Networks%耦合网络边相继故障模型研究

    Institute of Scientific and Technical Information of China (English)

    王建伟; 蒋晨; 孙恩慧

    2014-01-01

    In order to deal with cascading failures in coupled networks, this study analyzes the dynamics mechanism of cascading failures and propose the cascading failures′model of edge in coupled networks.To improve the robustness of coupled networks a-gainst cascading failures, according to different measures, this study takes multiple perspectives to analyze the correlation be-tween the robustness of coupled networks with different link patterns and some parameters in our model.this study then discusses the influences of link patterns of coupled networks and the basic network model on cascading failures and states the whole protec-tion strategies in the proposed model.This study finds: the assortative link pattern can enhance the robustness of coupled net-works against cascading failures;the more similar the topological structures of two interdependent networks, the stronger the net-work robustness against cascading failures;the robustness of coupled networks has a positive correlation with the average degree;an appropriate increase in the number of symmetrical edges between two networks can improve the network robustness.Finally, the cascading failures′model of edge in the real coupled power grid is analyzed.%针对耦合网络上频发的相继故障问题,通过分析边级联故障蔓延的动力学演化机制,构建耦合网络上边相继故障模型。以提高耦合网络整体抵制相继故障能力为出发点,依据不同度量指标,多角度分析具有不同耦合模式的耦合网络鲁棒性与模型参数之间的关联性,研究耦合网络间耦合模式和网络基本模型等因素对相继故障的影响,探讨耦合网络边相继故障模型的整体保护策略。研究结果表明,同配连接模式能够增强耦合网络抵制级联故障的鲁棒性;相互依赖的两个耦合网络之间拓扑结构越相似,网络抵制相继故障的鲁棒性越强;耦合网络鲁棒性与网络平均度正相关;适当的增加

  15. Cascaded-cladding-pumped cascaded Raman fiber amplifier.

    Science.gov (United States)

    Jiang, Huawei; Zhang, Lei; Feng, Yan

    2015-06-01

    The conversion efficiency of double-clad Raman fiber laser is limited by the cladding-to-core area ratio. To get high conversion efficiency, the inner-cladding-to-core area ratio has to be less than about 8, which limits the brightness enhancement. To overcome the problem, a cascaded-cladding-pumped cascaded Raman fiber laser with multiple-clad fiber as the Raman gain medium is proposed. A theoretical model of Raman fiber amplifier with multiple-clad fiber is developed, and numerical simulation proves that the proposed scheme can improve the conversion efficiency and brightness enhancement of cladding pumped Raman fiber laser.

  16. Spatial distribution and dose-response relationship for different operation modes in a reaction-diffusion model of the MAPK cascade

    Science.gov (United States)

    Zhao, Qi; Yi, Ming; Liu, Yan

    2011-10-01

    The mitogen-activated protein kinase (MAPK) cascade plays a critical role in the control of cell growth. Deregulation of this pathway contributes to the development of many cancers. To better understand its signal transduction, we constructed a reaction-diffusion model for the MAPK pathway. We modeled the three layers of phosphorylation-dephosphorylation reactions and diffusion processes from the cell membrane to the nucleus. Based on different types of feedback in the MAPK cascade, four operation modes are introduced. For each of the four modes, spatial distributions and dose-response curves of active kinases (i.e. ppMAPK) are explored by numerical simulation. The effects of propagation length, diffusion coefficient and feedback strength on the pathway dynamics are investigated. We found that intrinsic bistability in the MAPK cascade can generate a traveling wave of ppMAPK with constant amplitude when the propagation length is short. ppMAPK in this mode of intrinsic bistability decays more slowly than it does in all other modes as the propagation length increases. Moreover, we examined the global and local responses to Ras-GTP of these four modes, and demonstrated how the shapes of these dose-response curves change as the propagation length increases. Also, we found that larger diffusion constant gives a higher response level on the zero-order regime and makes the ppMAPK profiles flatter under strong Ras-GTP stimulus. Furthermore, we observed that spatial responses of ppMAPK are more sensitive to negative feedback than to positive feedback in the broader signal range. Finally, we showed how oscillatory signals pass through the kinase cascade, and found that high frequency signals are damped faster than low frequency ones.

  17. The Relationship between Reading Attitude, Metacognitive Awareness of Reading Strategies, Personality and Self-Regulation: A Study of Modeling

    Science.gov (United States)

    Turkyilmaz, Mustafa

    2015-01-01

    This study aimed at investigating the relationship between reading attitude, personality, self-regulation and metacognitive awareness of reading strategies of secondary school students. In order to carry out the aim four scales were used to 419 high school students in Kirsehir province in Turkey. It was used Lisrel 8.80 and SPSS software to…

  18. A Probabilistic Genome-Wide Gene Reading Frame Sequence Model

    DEFF Research Database (Denmark)

    Have, Christian Theil; Mørk, Søren

    using the probabilistic logic programming language and machine learning system PRISM - a fast and efficient model prototyping environment, using bacterial gene finding performance as a benchmark of signal strength. The model is used to prune a set of gene predictions from an underlying gene finder...

  19. Contingency Analysis of Cascading Line Outage Events

    Energy Technology Data Exchange (ETDEWEB)

    Thomas L Baldwin; Magdy S Tawfik; Miles McQueen

    2011-03-01

    As the US power systems continue to increase in size and complexity, including the growth of smart grids, larger blackouts due to cascading outages become more likely. Grid congestion is often associated with a cascading collapse leading to a major blackout. Such a collapse is characterized by a self-sustaining sequence of line outages followed by a topology breakup of the network. This paper addresses the implementation and testing of a process for N-k contingency analysis and sequential cascading outage simulation in order to identify potential cascading modes. A modeling approach described in this paper offers a unique capability to identify initiating events that may lead to cascading outages. It predicts the development of cascading events by identifying and visualizing potential cascading tiers. The proposed approach was implemented using a 328-bus simplified SERC power system network. The results of the study indicate that initiating events and possible cascading chains may be identified, ranked and visualized. This approach may be used to improve the reliability of a transmission grid and reduce its vulnerability to cascading outages.

  20. Characterization of the caspase cascade in a cell culture model of SOD1-related familial amyotrophic lateral sclerosis: expression, activation and therapeutic effects of inhibition.

    Science.gov (United States)

    Sathasivam, S; Grierson, A J; Shaw, P J

    2005-10-01

    There is increasing evidence that apoptosis or a similar programmed cell death pathway is the mechanism of cell death responsible for motor neurone degeneration in amyotrophic lateral sclerosis. Knowledge of the relative importance of different caspases in the cell death process is at present incomplete. In addition, there is little information on the critical point of the death pathway when the process of dying becomes irreversible. In this study, using the well-established NSC34 motor neurone-like cell line stably transfected with empty vector, normal or mutant human Cu-Zn superoxide dismutase (SOD1), we have characterized the activation of the caspase cascade in detail, revealing that the activation of caspases-9, -3 and -8 are important in motor neurone death and that the presence of mutant SOD1 causes increased activation of components of the apoptotic cascade under both basal culture conditions and following oxidative stress induced by serum withdrawal. Activation of the caspases identified in the cellular model has been confirmed in the G93A SOD1 transgenic mice. Furthermore, investigation of the effects of anti-apoptotic neuroprotective agents including specific caspase inhibitors, minocycline and nifedipine, have supported the importance of the mitochondrion-dependent apoptotic pathway in the death process and revealed that the upstream caspase cascade needs to be inhibited if useful neuro-protection is to be achieved.

  1. Energy Cascades in MHD

    Science.gov (United States)

    Alexakis, A.

    2009-04-01

    Most astrophysical and planetary systems e.g., solar convection and stellar winds, are in a turbulent state and coupled to magnetic fields. Understanding and quantifying the statistical properties of magneto-hydro-dynamic (MHD) turbulence is crucial to explain the involved physical processes. Although the phenomenological theory of hydro-dynamic (HD) turbulence has been verified up to small corrections, a similar statement cannot be made for MHD turbulence. Since the phenomenological description of Hydrodynamic turbulence by Kolmogorov in 1941 there have been many attempts to derive a similar description for turbulence in conducting fluids (i.e Magneto-Hydrodynamic turbulence). However such a description is going to be based inevitably on strong assumptions (typically borrowed from hydrodynamics) that do not however necessarily apply to the MHD case. In this talk I will discuss some of the properties and differences of the energy and helicity cascades in turbulent MHD and HD flows. The investigation is going to be based on the analysis of direct numerical simulations. The cascades in MHD turbulence appear to be a more non-local process (in scale space) than in Hydrodynamics. Some implications of these results to turbulent modeling will be discussed

  2. Vers un modele d'intervention precoce en lecture en actualisation linguistique (Towards a Model of Early Intervention in Reading Readiness).

    Science.gov (United States)

    Berger, Marie Josee

    1999-01-01

    Argues that in Ontario's French-medium schools, reading is often a challenge, particularly for those in readiness classes who speak little or no French. A model for early intervention in reading is recommended, combining reading and writing to address the linguistic challenges of students in a minority-language community. (Author/MSE)

  3. A Model of Motivation for Extensive Reading in Japanese as a Foreign Language

    Science.gov (United States)

    de Burgh-Hirabe, Ryoko; Feryok, Ann

    2013-01-01

    Numerous studies have reported that extensive reading (ER) has a positive influence on affect. Recent studies suggest that motivation for ER changes. This is in line with recent developments in second language (L2) motivation research that have highlighted the complex and dynamic nature of L2 motivation. This study presents a model of complex and…

  4. Exploring Reading Comprehension Skill Relationships through the G-DINA Model

    Science.gov (United States)

    Chen, Huilin; Chen, Jinsong

    2016-01-01

    By analysing the test data of 1029 British secondary school students' performance on 20 Programme for International Student Assessment English reading items through the generalised deterministic input, noisy "and" gate (G-DINA) model, the study conducted two investigations on exploring the relationships among the five reading…

  5. A Model of Motivation for Extensive Reading in Japanese as a Foreign Language

    Science.gov (United States)

    de Burgh-Hirabe, Ryoko; Feryok, Ann

    2013-01-01

    Numerous studies have reported that extensive reading (ER) has a positive influence on affect. Recent studies suggest that motivation for ER changes. This is in line with recent developments in second language (L2) motivation research that have highlighted the complex and dynamic nature of L2 motivation. This study presents a model of complex and…

  6. The Relationship between Victimization at School and Achievement: The Cusp Catastrophe Model for Reading Performance

    Science.gov (United States)

    Sideridis, Georgios D.; Antoniou, Faye; Stamovlasis, Dimitrios; Morgan, Paul L.

    2013-01-01

    We evaluated the relationship between victimization and academic achievement from a nonlinear perspective using a cusp catastrophe model. Participants were 62 students with identified learning disabilities (LD) using statewide criteria in Greece. Students participated in a 2-year cohort-sequential design. Reading assessments involved measures of…

  7. Defining and Comparing the Reading Comprehension Construct: A Cognitive-Psychometric Modeling Approach

    Science.gov (United States)

    Svetina, Dubravka; Gorin, Joanna S.; Tatsuoka, Kikumi K.

    2011-01-01

    As a construct definition, the current study develops a cognitive model describing the knowledge, skills, and abilities measured by critical reading test items on a high-stakes assessment used for selection decisions in the United States. Additionally, in order to establish generalizability of the construct meaning to other similarly structured…

  8. Exploring Reading Comprehension Skill Relationships through the G-DINA Model

    Science.gov (United States)

    Chen, Huilin; Chen, Jinsong

    2016-01-01

    By analysing the test data of 1029 British secondary school students' performance on 20 Programme for International Student Assessment English reading items through the generalised deterministic input, noisy "and" gate (G-DINA) model, the study conducted two investigations on exploring the relationships among the five reading…

  9. Vocabulary and Grammar Knowledge in Second Language Reading Comprehension: A Structural Equation Modeling Study

    Science.gov (United States)

    Zhang, Dongbo

    2012-01-01

    Using structural equation modeling analysis, this study examined the contribution of vocabulary and grammatical knowledge to second language reading comprehension among 190 advanced Chinese English as a foreign language learners. Vocabulary knowledge was measured in both breadth (Vocabulary Levels Test) and depth (Word Associates Test);…

  10. Training EFL Learners in Self-Regulation of Reading: Implementing an SRL Model

    Science.gov (United States)

    Morshedian, Mahboobeh; Hemmati, Fatemeh; Sotoudehnama, Elaheh

    2017-01-01

    This study examined whether training English as a foreign language (EFL) learners in a self-regulated learning (SRL) model could help them develop the ability to self-regulate their reading in English and whether their proficiency level could moderate the efficacy of self-regulation training. Two experimental groups received instruction in…

  11. Using Peer Collaboration to Support Online Reading, Writing, and Communication: An Empowerment Model for Struggling Readers

    Science.gov (United States)

    Henry, Laurie A.; Castek, Jill; O'Byrne, W. Ian; Zawilinski, Lisa

    2012-01-01

    This comparative case study investigated the implementation of an empowerment model for struggling readers that utilized the Internet as a context for reading, writing, and communicating in 3 different classroom contexts. Through student-centered techniques, such as flexible grouping and peer teaching, we designed Internet Reciprocal Teaching to…

  12. Longitudinal Models of Developmental Dynamics Between Reading and Cognition from Childhood to Adolescence

    Science.gov (United States)

    Ferrer, Emilio; McArdle, John J.; Shaywitz, Bennett A.; Holahan, John M.; Marchione, Karen; Shaywitz, Sally E.

    2007-01-01

    The authors applied linear dynamic models to longitudinal data to examine the dynamics of reading and cognition from 1st to 12th grade. They used longitudinal data (N=445) from the Connecticut Longitudinal Study (S. E. Shaywitz, B. A. Shaywitz, J. M. Fletcher, & M. D. Escobar, 1990) to map the dynamic interrelations of various scales of the…

  13. Applying a Multiple Group Causal Indicator Modeling Framework to the Reading Comprehension Skills of Third, Seventh, and Tenth Grade Students

    Science.gov (United States)

    Tighe, Elizabeth L.; Wagner, Richard K.; Schatschneider, Christopher

    2015-01-01

    This study demonstrates the utility of applying a causal indicator modeling framework to investigate important predictors of reading comprehension in third, seventh, and tenth grade students. The results indicated that a 4-factor multiple indicator multiple indicator cause (MIMIC) model of reading comprehension provided adequate fit at each grade level. This model included latent predictor constructs of decoding, verbal reasoning, nonverbal reasoning, and working memory and accounted for a large portion of the reading comprehension variance (73% to 87%) across grade levels. Verbal reasoning contributed the most unique variance to reading comprehension at all grade levels. In addition, we fit a multiple group 4-factor MIMIC model to investigate the relative stability (or variability) of the predictor contributions to reading comprehension across development (i.e., grade levels). The results revealed that the contributions of verbal reasoning, nonverbal reasoning, and working memory to reading comprehension were stable across the three grade levels. Decoding was the only predictor that could not be constrained to be equal across grade levels. The contribution of decoding skills to reading comprehension was higher in third grade and then remained relatively stable between seventh and tenth grade. These findings illustrate the feasibility of using MIMIC models to explain individual differences in reading comprehension across the development of reading skills. PMID:25821346

  14. Applying a Multiple Group Causal Indicator Modeling Framework to the Reading Comprehension Skills of Third, Seventh, and Tenth Grade Students

    Science.gov (United States)

    Tighe, Elizabeth L.; Wagner, Richard K.; Schatschneider, Christopher

    2015-01-01

    This study demonstrates the utility of applying a causal indicator modeling framework to investigate important predictors of reading comprehension in third, seventh, and tenth grade students. The results indicated that a 4-factor multiple indicator multiple indicator cause (MIMIC) model of reading comprehension provided adequate fit at each grade…

  15. The Effects of Video Self-Modeling on the Decoding Skills of Children at Risk for Reading Disabilities

    Science.gov (United States)

    Ayala, Sandra M.; O'Connor, Rollanda

    2013-01-01

    Ten first grade students who had responded poorly to a Tier 2 reading intervention in a response to intervention (RTI) model received an intervention of video self-modeling to improve decoding skills and sight word recognition. Students were video recorded blending and segmenting decodable words and reading sight words. Videos were edited and…

  16. Applying a Multiple Group Causal Indicator Modeling Framework to the Reading Comprehension Skills of Third, Seventh, and Tenth Grade Students

    Science.gov (United States)

    Tighe, Elizabeth L.; Wagner, Richard K.; Schatschneider, Christopher

    2015-01-01

    This study demonstrates the utility of applying a causal indicator modeling framework to investigate important predictors of reading comprehension in third, seventh, and tenth grade students. The results indicated that a 4-factor multiple indicator multiple indicator cause (MIMIC) model of reading comprehension provided adequate fit at each grade…

  17. The componential model of reading: predicting first grade reading performance of culturally diverse students from ecological, psychological, and cognitive factors assessed at kindergarten entry.

    Science.gov (United States)

    Ortiz, Miriam; Folsom, Jessica S; Al Otaiba, Stephanie; Greulich, Luana; Thomas-Tate, Shurita; Connor, Carol M

    2012-01-01

    This study, framed by the component model of reading (CMR), examined the relative importance of kindergarten-entry predictors of first grade reading performance. Specifically, elements within the ecological domain included dialect, maternal education, amount of preschool, and home literacy; elements within the psychological domain included teacher-reported academic competence, social skills, and behavior; and elements within the cognitive domain included initial vocabulary, phonological, and morpho-syntactic skills, and alphabetic and word recognition skills. Data were obtained for 224 culturally diverse kindergarteners (58% Black, 34% White, and 8% Hispanic or other; 58% received free or reduced-price lunch) from a larger study conducted in seven predominantly high poverty schools (n = 20 classrooms) in a midsized city school district in northern Florida. Results from a hierarchical multiple regression (with variables in the ecological domain entered first, followed by the psychological and cognitive domains) revealed a model that explained roughly 56% of the variance in first grade reading achievement, using fall-of-kindergarten predictors. Letter-word reading and morpho-syntactic skill were the strongest significant predictors. The findings largely support the CMR model as a means to understand individual differences in reading acquisition and, in turn, to support data-based instructional decisions for a wider range of children.

  18. Cascading failures and the emergence of cooperation in evolutionary-game based models of social and economical networks.

    Science.gov (United States)

    Wang, Wen-Xu; Lai, Ying-Cheng; Armbruster, Dieter

    2011-09-01

    We study catastrophic behaviors in large networked systems in the paradigm of evolutionary games by incorporating a realistic "death" or "bankruptcy" mechanism. We find that a cascading bankruptcy process can arise when defection strategies exist and individuals are vulnerable to deficit. Strikingly, we observe that, after the catastrophic cascading process terminates, cooperators are the sole survivors, regardless of the game types and of the connection patterns among individuals as determined by the topology of the underlying network. It is necessary that individuals cooperate with each other to survive the catastrophic failures. Cooperation thus becomes the optimal strategy and absolutely outperforms defection in the game evolution with respect to the "death" mechanism. Our results can be useful for understanding large-scale catastrophe in real-world systems and in particular, they may yield insights into significant social and economical phenomena such as large-scale failures of financial institutions and corporations during an economic recession.

  19. Modelling reading development through phonological decoding and self-teaching: implications for dyslexia.

    Science.gov (United States)

    Ziegler, Johannes C; Perry, Conrad; Zorzi, Marco

    2014-01-01

    The most influential theory of learning to read is based on the idea that children rely on phonological decoding skills to learn novel words. According to the self-teaching hypothesis, each successful decoding encounter with an unfamiliar word provides an opportunity to acquire word-specific orthographic information that is the foundation of skilled word recognition. Therefore, phonological decoding acts as a self-teaching mechanism or 'built-in teacher'. However, all previous connectionist models have learned the task of reading aloud through exposure to a very large corpus of spelling-sound pairs, where an 'external' teacher supplies the pronunciation of all words that should be learnt. Such a supervised training regimen is highly implausible. Here, we implement and test the developmentally plausible phonological decoding self-teaching hypothesis in the context of the connectionist dual process model. In a series of simulations, we provide a proof of concept that this mechanism works. The model was able to acquire word-specific orthographic representations for more than 25 000 words even though it started with only a small number of grapheme-phoneme correspondences. We then show how visual and phoneme deficits that are present at the outset of reading development can cause dyslexia in the course of reading development.

  20. Characterisation and modelling of transition edge sensor distributed read-out imaging devices

    Science.gov (United States)

    Smith, Stephen J.; Whitford, Chris H.; Fraser, George W.; Goldie, David J.

    2006-04-01

    We report on the experimental characterisation and modelling of Transition Edge Sensor (TES)-based Distributed Read-Out Imaging Devices (DROIDs), for use as position-sensitive detectors in X-ray astronomy. Latest experimental results from prototype DROIDs using Ir TESs with Au absorbers are reported. Through modelling and the development of signal processing algorithms we are able to design the DROID for optimum spectral and spatial resolution depending upon application.

  1. Characterisation and modelling of transition edge sensor distributed read-out imaging devices

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Stephen J. [Department of Physics and Astronomy, Space Research Centre, Leicester University, Michael Atiyah Building, University Road, Leicester, LE1 7RH (United Kingdom)]. E-mail: sts@star.le.ac.uk; Whitford, Chris H. [Department of Physics and Astronomy, Space Research Centre, Leicester University, Michael Atiyah Building, University Road, Leicester, LE1 7RH (United Kingdom); Fraser, George W. [Department of Physics and Astronomy, Space Research Centre, Leicester University, Michael Atiyah Building, University Road, Leicester, LE1 7RH (United Kingdom); Goldie, David J. [Astrophysics Group, Cavendish Laboratory, Department of Physics, Cambridge University, Madingley Road Cambridge, CB3 OHE (United Kingdom)

    2006-04-15

    We report on the experimental characterisation and modelling of Transition Edge Sensor (TES)-based Distributed Read-Out Imaging Devices (DROIDs), for use as position-sensitive detectors in X-ray astronomy. Latest experimental results from prototype DROIDs using Ir TESs with Au absorbers are reported. Through modelling and the development of signal processing algorithms we are able to design the DROID for optimum spectral and spatial resolution depending upon application.

  2. Earthquake sequence simulation of a multi-scale asperity model following rate and state friction - occurrence of large earthquakes by cascade up vs. own nucleation

    Science.gov (United States)

    Noda, H.; Nakatani, M.; Hori, T.

    2012-12-01

    Seismological observations [e.g., Abercrombie and Rice, 2005] suggest that a larger earthquake has larger fracture energy Gc. One way to realize such scaling is to assume a hierarchical patchy distribution of Gc on a fault; there are patches of different sizes with different Gc so that a larger patch has larger Gc. Ide and Aochi [2005] conducted dynamic rupture simulations with such a distribution of weakening distance Dc in a linear slip-weakening law, initiating ruptures on the smallest patch which sometimes grow up by cascading into a larger scale. They suggested that the initial phase of a large earthquake is indistinguishable from that of a small earthquake. In the present study we simulate a similar multi-scale asperity model but following rate and state friction (RSF), where stress and strength distribution resulting from the history of coseismic and aseismic slip influences the way of rupture initiation, growth, and arrest of a forthcoming earthquake. Multi-scale asperities were represented by a distribution of the state evolution distance dc in the aging version of RSF evolution law. Numerical scheme adopted [Noda and Lapsuta, 2010] is fully dynamic and 3D. We have modeled a circular rate-weakening patch, Patch L (radius R), which has a smaller patch, Patch S (radius r), in it by the rim. The ratio of the radii α = R/r is the amount of the gap between two scales. Patch L and Patch S respectively have nucleation sizes Rc and rc. The same brittleness β = R/Rc = r/rc is assumed for simplicity. We shall call an earthquake which ruptures only Patch S as an S-event, and one which ruptures Patch L, an L-event. We have conducted a series of simulations with α from 2 to 5 while keeping β = 3 until the end of the 20th L-event. If the patch S was relatively large (α = 2 and 2.5), only L-events occurred and they always dynamically cascaded up from a patch S rupture following small quasi-static nucleation there. If the patch S was small enough (α = 5), in

  3. Modelling water quality and quantity with the influence of inter-basin water diversion projects and cascade reservoirs in the Middle-lower Hanjiang River

    Science.gov (United States)

    Wang, Yonggui; Zhang, Wanshun; Zhao, Yanxin; Peng, Hong; Shi, Yingyuan

    2016-10-01

    The effects of inter-basin water diversion projects and cascade reservoirs are typically complex and challenging, as the uncertain temporal-spatial variation of both water quality and quantity. The purpose of this paper is to propose a coupled 1D hydrodynamic model with water-quality model to analyze the effects of current and future inter-basin water diversion projects, i.e., South-to-North Water Diversion Project (SNWD) and Yangtze-Hanjiang Water Diversion Project (YHWD), and cascade reservoirs (CRS) on water quantity and quality in the middle-lower Hanjiang River. Considering water use and pollution contribution, the middle-lower Hanjaing River basin is generalized and divided into 18 land use units with tributaries, reservoirs and water exchanges. Each unit is considered with the processes of lateral inflow, point and non-point pollution loads, irrigation return flow, and stream-aquifer exchanges in the model. The long-term time series from 1956 to 1998 of water quality and quantity with four engineering scenarios is collected. The validation of results shows that the relative errors between the simulated and observed values at certain control sections are within 5% for water levels and 20% for water quality. The water level will be decreased by 0.38-0.65 m (decreasing rate 0.44-2.68%), the annual runoff will be significantly decreased over 4 billion m3 and the water quality will be changed after the SNWD. As a compensation project, the YHWD partly offsets the negative effects of the SNWD in water flow rate, but at the same time it rises the water level and reduces the flow velocity. This, together with the effect of cascade reservoirs, leads to water quality concentration increasing and deteriorating to Grade IV of the Chinese Surface Water Quality Criteria. The water resource reduction and water quality problems in the Middle-lower Hanjiang River require attention after these projects.

  4. Population Dynamics and Emission Spectrum of a Cascade Three-Level Jaynes-Cummings Model with Intensity-Dependent Coupling in a Kerr-like Medium

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    By using the method of eigenvectors, the atomic populations and emission spectrum are investigated in a system that consists of a cascade three-level atom resonantly interacting with a single-mode field in a Kerr-like medium.The atom and the field are assumed to be initially in the upper atomic state and the Fock state, respectively. Results for models with intensity-dependent coupling and with intensity-independent coupling are compared. It is found that both population dynamics and emission spectrum show no indications of atom-field decoupling in the strong field limit if the intensity-dependent coupling is taken into account.

  5. Cascades on clique-based graphs

    Science.gov (United States)

    Hackett, Adam; Gleeson, James P.

    2013-06-01

    We present an analytical approach to determining the expected cascade size in a broad range of dynamical models on the class of highly clustered random graphs introduced by Gleeson [J. P. Gleeson, Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.80.036107 80, 036107 (2009)]. A condition for the existence of global cascades is also derived. Applications of this approach include analyses of percolation, and Watts's model. We show how our techniques can be used to study the effects of in-group bias in cascades on social networks.

  6. A cascaded model of spectral distortions due to spectral response effects and pulse pileup effects in a photon-counting x-ray detector for CT

    Energy Technology Data Exchange (ETDEWEB)

    Cammin, Jochen, E-mail: jcammin1@jhmi.edu, E-mail: ktaguchi@jhmi.edu; Taguchi, Katsuyuki, E-mail: jcammin1@jhmi.edu, E-mail: ktaguchi@jhmi.edu [Division of Medical Imaging Physics, The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287 (United States); Xu, Jennifer [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21287 (United States); Barber, William C.; Iwanczyk, Jan S.; Hartsough, Neal E. [DxRay, Inc., Northridge, California 91324 (United States)

    2014-04-15

    Purpose: Energy discriminating, photon-counting detectors (PCDs) are an emerging technology for computed tomography (CT) with various potential benefits for clinical CT. The photon energies measured by PCDs can be distorted due to the interactions of a photon with the detector and the interaction of multiple coincident photons. These effects result in distorted recorded x-ray spectra which may lead to artifacts in reconstructed CT images and inaccuracies in tissue identification. Model-based compensation techniques have the potential to account for the distortion effects. This approach requires only a small number of parameters and is applicable to a wide range of spectra and count rates, but it needs an accurate model of the spectral distortions occurring in PCDs. The purpose of this study was to develop a model of those spectral distortions and to evaluate the model using a PCD (model DXMCT-1; DxRay, Inc., Northridge, CA) and various x-ray spectra in a wide range of count rates. Methods: The authors hypothesize that the complex phenomena of spectral distortions can be modeled by: (1) separating them into count-rate independent factors that we call the spectral response effects (SRE), and count-rate dependent factors that we call the pulse pileup effects (PPE), (2) developing separate models for SRE and PPE, and (3) cascading the SRE and PPE models into a combined SRE+PPE model that describes PCD distortions at both low and high count rates. The SRE model describes the probability distribution of the recorded spectrum, with a photo peak and a continuum tail, given the incident photon energy. Model parameters were obtained from calibration measurements with three radioisotopes and then interpolated linearly for other energies. The PPE model used was developed in the authors’ previous work [K. Taguchi et al., “Modeling the performance of a photon counting x-ray detector for CT: Energy response and pulse pileup effects,” Med. Phys. 38(2), 1089–1102 (2011

  7. Research on modeling technology based on Qt and OpenCASCADE%基于Qt及OpenCASCADE的建模技术研究

    Institute of Scientific and Technical Information of China (English)

    袁媛; 王延红; 江凌; 林成地; 王玥

    2013-01-01

    Qt is a cross⁃platform class GUI library of C++ provided by TrollTech Corporation in Norway. It gives all func⁃tions needed by application program developers of creating GUI. OpenCASCADE uses the professional CAD library based on OpenGL. It can be used in the fields of CAD software development,simulation software design and 3D graphic displaying. Modeling software can be developed when Qt and OpenCASCADE are integrated in the C++ environment. The main functions of the library of Qt and OpenCASCADE are introduced. Boundary representation is narrated in brief. The definition of geometry and topology is given. Data type and structure in OCC is expounded. The practice programming indicates that Qt and OpenCASCADE library can be used to create various complicate models with the perfect vision effect. They can be the developing tools of geome⁃try modeling software.%  Qt是挪威TrollTech公司推出的一个跨平台的C++图形用户界面库,提供给应用程序开发者建立图形用户界面所需的所有功能。OpenCASCADE采用基于OpenGL的专用CAD类库,可应用于CAD软件开发、仿真软件设计和三维图形显示等领域。将Qt和OpenCASCADE在C++环境下结合起来能够进行建模软件的开发。介绍了Qt及OpenCASCADE类库的主要功能,简要叙述了边界表示法,给出了几何和拓扑的定义,对OCC中的数据类型和数据结构进行了阐述。经过实际的编程开发,结果表明,Qt及OpenCASCADE类库能够建立多种复杂模型,且拥有较好的显示效果,适合作为几何建模软件的开发工具。

  8. Modeling a Cascade of Effects: The Role of Speed and Executive Functioning in Preterm/Full-Term Differences in Academic Achievement

    Science.gov (United States)

    Rose, Susan A.; Feldman, Judith F.; Jankowski, Jeffery J.

    2011-01-01

    This study identified deficits in executive functioning in pre-adolescent preterms and modeled their role, along with processing speed, in explaining preterm/full-term differences in reading and mathematics. Preterms (less than 1750 g) showed deficits at 11 years on a battery of tasks tapping the three basic executive functions identified by…

  9. Geodetic observations and modeling of magmatic inflation at the Three Sisters volcanic center, central Oregon Cascade Range, USA

    Science.gov (United States)

    Dzurisin, Daniel; Lisowski, Michael; Wicks, Charles W.; Poland, Michael P.; Endo, Elliot T.

    2006-01-01

    Tumescence at the Three Sisters volcanic center began sometime between summer 1996 and summer 1998 and was discovered in April 2001 using interferometric synthetic aperture radar (InSAR). Swelling is centered about 5 km west of the summit of South Sister, a composite basaltic-andesite to rhyolite volcano that last erupted between 2200 and 2000 yr ago, and it affects an area ∼20 km in diameter within the Three Sisters Wilderness. Yearly InSAR observations show that the average maximum displacement rate was 3–5 cm/yr through summer 2001, and the velocity of a continuous GPS station within the deforming area was essentially constant from June 2001 to June 2004. The background level of seismic activity has been low, suggesting that temperatures in the source region are high enough or the strain rate has been low enough to favor plastic deformation over brittle failure. A swarm of about 300 small earthquakes (Mmax = 1.9) in the northeast quadrant of the deforming area on March 23–26, 2004, was the first notable seismicity in the area for at least two decades. The U.S. Geological Survey (USGS) established tilt-leveling and EDM networks at South Sister in 1985–1986, resurveyed them in 2001, the latter with GPS, and extended them to cover more of the deforming area. The 2001 tilt-leveling results are consistent with the inference drawn from InSAR that the current deformation episode did not start before 1996, i.e., the amount of deformation during 1995–2001 from InSAR fully accounts for the net tilt at South Sister during 1985–2001 from tilt-leveling. Subsequent InSAR, GPS, and leveling observations constrain the source location, geometry, and inflation rate as a function of time. A best-fit source model derived from simultaneous inversion of all three datasets is a dipping sill located 6.5 ± 2.5 km below the surface with a volume increase of 5.0 × 106 ± 1.5 × 106m3/yr (95% confidence limits). The most likely cause of tumescence is a pulse of

  10. Modeling the Relations Among Morphological Awareness Dimensions, Vocabulary Knowledge, and Reading Comprehension in Adult Basic Education Students.

    Science.gov (United States)

    Tighe, Elizabeth L; Schatschneider, Christopher

    2016-01-01

    This study extended the findings of Tighe and Schatschneider (2015) by investigating the predictive utility of separate dimensions of morphological awareness as well as vocabulary knowledge to reading comprehension in adult basic education (ABE) students. We competed two- and three-factor structural equation models of reading comprehension. A three-factor model of real word morphological awareness, pseudoword morphological awareness, and vocabulary knowledge emerged as the best fit and accounted for 79% of the reading comprehension variance. The results indicated that the constructs contributed jointly to reading comprehension; however, vocabulary knowledge was the only potentially unique predictor (p = 0.052), accounting for an additional 5.6% of the variance. This study demonstrates the feasibility of applying a latent variable modeling approach to examine individual differences in the reading comprehension skills of ABE students. Further, this study replicates the findings of Tighe and Schatschneider (2015) on the importance of differentiating among dimensions of morphological awareness in this population.

  11. Modeling the Relations Among Morphological Awareness Dimensions, Vocabulary Knowledge, and Reading Comprehension in Adult Basic Education Students

    Science.gov (United States)

    Tighe, Elizabeth L.; Schatschneider, Christopher

    2016-01-01

    This study extended the findings of Tighe and Schatschneider (2015) by investigating the predictive utility of separate dimensions of morphological awareness as well as vocabulary knowledge to reading comprehension in adult basic education (ABE) students. We competed two- and three-factor structural equation models of reading comprehension. A three-factor model of real word morphological awareness, pseudoword morphological awareness, and vocabulary knowledge emerged as the best fit and accounted for 79% of the reading comprehension variance. The results indicated that the constructs contributed jointly to reading comprehension; however, vocabulary knowledge was the only potentially unique predictor (p = 0.052), accounting for an additional 5.6% of the variance. This study demonstrates the feasibility of applying a latent variable modeling approach to examine individual differences in the reading comprehension skills of ABE students. Further, this study replicates the findings of Tighe and Schatschneider (2015) on the importance of differentiating among dimensions of morphological awareness in this population. PMID:26869981

  12. Cascade quantum teleportation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Nan-run; GONG Li-hua; LIU Ye

    2006-01-01

    In this letter a cascade quantum teleportation scheme is proposed. The proposed scheme needs less local quantum operations than those of quantum multi-teleportation. A quantum teleportation scheme based on entanglement swapping is presented and compared with the cascade quantum teleportation scheme. Those two schemes can effectively teleport quantum information and extend the distance of quantum communication.

  13. Elementary School ELLs' Reading Skill Profiles Using Cognitive Diagnosis Modeling: Roles of Length of Residence and Home Language Environment

    Science.gov (United States)

    Jang, Eunice Eunhee; Dunlop, Maggie; Wagner, Maryam; Kim, Youn-Hee; Gu, Zhimei

    2013-01-01

    The study examined differences in reading achievement and mastery skill development among Grade-6 students with different language background profiles, using cognitive diagnosis modeling applied to large-scale provincial reading test performance data. Our analyses revealed that students residing in various home language environments show different…

  14. On the Evidence of Theory: Close Reading as a Disciplinary Model for Writing about Teaching and Learning

    Science.gov (United States)

    Bass, Randy; Linkon, Sherry Lee

    2008-01-01

    While some literary scholars claim that their discipline's research practices do not fit the scholarship of teaching and learning, close reading--the signature critical practice of literary studies--provides a useful model. Close reading involves not only attention to the text but also the integration of text and theory. This article analyzes how…

  15. Bankruptcy Cascades in Interbank Markets

    Science.gov (United States)

    Tedeschi, Gabriele; Mazloumian, Amin; Gallegati, Mauro; Helbing, Dirk

    2012-01-01

    We study a credit network and, in particular, an interbank system with an agent-based model. To understand the relationship between business cycles and cascades of bankruptcies, we model a three-sector economy with goods, credit and interbank market. In the interbank market, the participating banks share the risk of bad debits, which may potentially spread a bank’s liquidity problems through the network of banks. Our agent-based model sheds light on the correlation between bankruptcy cascades and the endogenous economic cycle of booms and recessions. It also demonstrates the serious trade-off between, on the one hand, reducing risks of individual banks by sharing them and, on the other hand, creating systemic risks through credit-related interlinkages of banks. As a result of our study, the dynamics underlying the meltdown of financial markets in 2008 becomes much better understandable. PMID:23300760

  16. Bankruptcy cascades in interbank markets.

    Science.gov (United States)

    Tedeschi, Gabriele; Mazloumian, Amin; Gallegati, Mauro; Helbing, Dirk

    2012-01-01

    We study a credit network and, in particular, an interbank system with an agent-based model. To understand the relationship between business cycles and cascades of bankruptcies, we model a three-sector economy with goods, credit and interbank market. In the interbank market, the participating banks share the risk of bad debits, which may potentially spread a bank's liquidity problems through the network of banks. Our agent-based model sheds light on the correlation between bankruptcy cascades and the endogenous economic cycle of booms and recessions. It also demonstrates the serious trade-off between, on the one hand, reducing risks of individual banks by sharing them and, on the other hand, creating systemic risks through credit-related interlinkages of banks. As a result of our study, the dynamics underlying the meltdown of financial markets in 2008 becomes much better understandable.

  17. Bankruptcy cascades in interbank markets.

    Directory of Open Access Journals (Sweden)

    Gabriele Tedeschi

    Full Text Available We study a credit network and, in particular, an interbank system with an agent-based model. To understand the relationship between business cycles and cascades of bankruptcies, we model a three-sector economy with goods, credit and interbank market. In the interbank market, the participating banks share the risk of bad debits, which may potentially spread a bank's liquidity problems through the network of banks. Our agent-based model sheds light on the correlation between bankruptcy cascades and the endogenous economic cycle of booms and recessions. It also demonstrates the serious trade-off between, on the one hand, reducing risks of individual banks by sharing them and, on the other hand, creating systemic risks through credit-related interlinkages of banks. As a result of our study, the dynamics underlying the meltdown of financial markets in 2008 becomes much better understandable.

  18. Emerging Theoretical Models of Reading through Authentic Assessments among Preservice Teachers: Two Case Studies

    Science.gov (United States)

    Oboler, Eileen S.; Gupta, Abha

    2010-01-01

    This two-part study examines the emerging understanding of the reading process among preservice teachers (PTs), enrolled in a teacher preparation course on diagnostic reading. The study focuses on the use of reading assessment tools to understand the process of reading, while using reading inventories for diagnostic as well as pedagogical…

  19. Reading Guided by Automated Graphical Representations: How Model-Based Text Visualizations Facilitate Learning in Reading Comprehension Tasks

    Science.gov (United States)

    Pirnay-Dummer, Pablo; Ifenthaler, Dirk

    2011-01-01

    Our study integrates automated natural language-oriented assessment and analysis methodologies into feasible reading comprehension tasks. With the newly developed T-MITOCAR toolset, prose text can be automatically converted into an association net which has similarities to a concept map. The "text to graph" feature of the software is based on…

  20. Cascades in model steels: The effect of cementite (Fe3C) and Cr23C6 particles on short-term crystal damage

    Science.gov (United States)

    Henriksson, K. O. E.

    2015-06-01

    Ferritic stainless steel can be modeled as an iron matrix containing precipitates of cementite (Fe3C) and Cr23C6. When used in nuclear power production the steels in the vicinity of the core start to accumulate damage due to neutrons. The role of the afore-mentioned carbides in this process is not well understood. In order to clarify the situation bulk cascades created by primary recoils in model steels have been carried out in the present work. Investigated configurations consisted of bulk ferrite containing spherical particles (diameter of 4 nm) of either (1) Fe3C or (2) Cr23C6. Primary recoils were initiated at different distances from the inclusions, with recoil energies varying between 100 eV and 1 keV. Results for the number of point defects such as vacancies and antisites are presented. These findings indicate that defects are also remaining when cascades are started outside the carbide inclusions. The work uses a recently developed Abell-Brenner-Tersoff potential for the Fe-Cr-C system.

  1. List context effects in languages with opaque and transparent orthographies: a challenge for models of reading

    Science.gov (United States)

    Traficante, Daniela; Burani, Cristina

    2014-01-01

    This paper offers a review of data which show that reading is a flexible and dynamic process and that readers can exert strategic control over it. Two main hypotheses on the control of reading processes have been suggested: the route de-emphasis hypothesis and the time-criterion hypothesis. According to the former, the presence of irregular words in the list might lead to an attenuation of the non-lexical process, while the presence of non-words could trigger a de-emphasis of the lexical route. An alternative account is proposed by the time-criterion hypothesis whereby the reader sets a flexible deadline to initiate the response. According to the latter view, it is the average pronunciation difficulty of the items in the block that modulates the time-criterion for response. However, it is worth noting that the list composition has been shown to exert different effects in transparent compared to opaque orthographies, as the consistency of spelling-sound correspondences can influence the processing costs of the non-lexical pathway. In transparent orthographies, the non-lexical route is not resource demanding and can successfully contribute to the pronunciation of regular words, thus its de-emphasis could not be as useful/necessary as in opaque orthographies. The complex patterns of results from the literature on list context effects are a challenge for computational models of reading which face the problem of simulating strategic control over reading processes. Different proposals suggest a modification of parameter setting in the non-lexical route or the implementation of a new module aimed at focusing attention on the output of the more convenient pathway. Simulation data and an assessment of the models’ fit to the behavioral results are presented and discussed to shed light on the role of the cognitive system when reading aloud. PMID:25309485

  2. List context effects in languages with opaque and transparent orthographies: A challenge for models of reading

    Directory of Open Access Journals (Sweden)

    Daniela eTraficante

    2014-09-01

    Full Text Available This paper offers a review of data which show that reading is a flexible and dynamic process and that readers can exert strategic control over it. Two main hypotheses on the control of reading processes have been suggested: the route de-emphasis hypothesis and the time-criterion hypothesis. According to the former, the presence of irregular words in the list might lead to an attenuation of the non-lexical process, while the presence of non-words could trigger a de-emphasis of the lexical route. An alternative account is proposed by the time-criterion hypothesis whereby the reader sets a flexible deadline to initiate the response. According to the latter view, it is the average pronunciation difficulty of the items in the block that modulates the time-criterion for response. However, it is worth noting that the list composition has been shown to exert different effects in transparent compared to opaque orthographies, as the consistency of spelling-sound correspondences can influence the processing costs of the non-lexical pathway. In transparent orthographies, the non-lexical route is not resource demanding and can successfully contribute to the pronunciation of regular words, thus its de-emphasis could not be as useful/necessary as in opaque orthographies. The complex patterns of results from the literature on list context effects are a challenge for computational models of reading which face the problem of simulating strategic control over reading processes. Different proposals suggest a modification of parameter setting in the non-lexical route or the implementation of a new module aimed at focusing attention on the output of the more convenient pathway. Simulation data and an assessment of the models’ fit to the behavioral results are presented and discussed to shed light on the role of the cognitive system when reading aloud.

  3. Trophic cascades of bottom-up and top-down forcing on nutrients and plankton in the Kattegat, evaluated by modelling

    DEFF Research Database (Denmark)

    Petersen, Marcell Elo; Maar, Marie; Larsen, Janus

    2017-01-01

    The aim of the study was to investigate the relative importance of bottom-up and top-down forcing on trophic cascades in the pelagic food-web and the implications for water quality indicators (summer phytoplankton biomass and winter nutrients) in relation to management. The 3D ecological model....... On annual basis, the system was more bottom-up than top-down controlled. Microzooplankton was found to play an important role in the pelagic food web as mediator of nutrient and energy fluxes. This study demonstrated that the best scenario for improved water quality was a combined reduction in nutrient...... ERGOM was validated and applied in a local set-up of the Kattegat, Denmark, using the off-line Flexsem framework. The model scenarios were conducted by changing the forcing by ±20% of nutrient inputs (bottom-up) and mesozooplankton mortality (top-down), and both types of forcing combined. The model...

  4. Scaling laws of wave-cascading superfluid turbulence

    Science.gov (United States)

    Narita, Y.

    2017-06-01

    Phenomenological model is constructed for superfluid turbulence for two distinct energy cascade scenarios, sound wave cascade and critically-balanced Kelvin wave cascade, using the method for magneto-fluid turbulence theory. Excitations along dispersion relations are used as the primary energy reservoir. The spectral indices in the inertial range are estimated as -3/2 for the long-wavelength sound wave cascade, -3 in the direction to the mean filaments for the Kelvin wave cascade, and -5/3 perpendicular to the filament direction.

  5. Modeling and measurement of the noise figure of a cascaded non-degenerate phase-sensitive parametric amplifier.

    Science.gov (United States)

    Tong, Zhi; Bogris, Adonis; Lundström, Carl; McKinstrie, C J; Vasilyev, Michael; Karlsson, Magnus; Andrekson, Peter A

    2010-07-01

    Semi-classical noise characteristics are derived for the cascade of a non-degenerate phase-insensitive (PI) and a phase-sensitive (PS) fiber optical parametric amplifier (FOPA). The analysis is proved to be consistent with the quantum theory under the large-photon number assumption. Based on this, we show that the noise figure (NF) of the PS-FOPA at the second stage can be obtained via relative-intensity-noise (RIN) subtraction method after averaging the signal and idler NFs. Negative signal and idler NFs are measured, and 16 dB PS gain is estimated when considering the combined signal and idler input, which is believed to be the lowest measured NF of a non-degenerate PS amplifier to this date. The limitation of the RIN subtraction method attributed to pump transferred noise and Raman phonon induced noise is also discussed.

  6. Efficient Modeling for Cascading Multilevel Converters%级联多电平换流器的高效仿真模型

    Institute of Scientific and Technical Information of China (English)

    罗雨; 饶宏; 许树楷; 黎小林

    2014-01-01

    The cascading Multilevel Converter is a promising converter topology in both fields of Flexible AC transmission systems (FACTS) and Flexible High Voltage Direct Current (HVDC) Transmission. Since this topology is based on a large amount of cascading Sub-Modules, it contains many independent switch branches. If this topology is simulated by the detailed device modeling in the EMTP-type program (such as PSCAD/EMTDC), the time consumed in a single simulation instance can be so long that it becomes an obstacle in the research and design process. An modeling method, based on the EMTP principle invented by Dommel H.W. , for cascading multilevel converters was proposed in this paper which can efficiently solve this problem. The principle behind this method is clear, thus simulation results based on the proposed method are reliable. Validation simulation in PSCAD/EMTDC was provided. The simulation results show that the response of the proposed modeling method coincide with detailed device modeling, meanwhile it has a decided advantage in simulation time consumation.%级联多电平换流器是目前在柔性交直流输配电领域极具发展潜力的换流器拓扑,然而由于其拓扑中有大量独立的开关器件支路,如果在 EMTP 类仿真软件(如 PSCAD/EMTDC)中采用器件模型直接建模将使得仿真计算极其缓慢,给研究及工程应用带来障碍。提出一种基于 Dommel等值计算原理的级联多电平换流器仿真等值计算模型,可有效地解决仿真计算缓慢的问题,具有建模原理明确、计算结果可靠的优点。使用PSCAD/EMTDC软件对所提仿真模型进行仿真验证,结果表明,所提仿真计算模型与详细器件模型在暂态仿真中的响应高度一致,并且在仿真计算时间上具有明显的优势。

  7. Cascade of links in complex networks

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Yeqian; Sun, Bihui [Department of Management Science, School of Government, Beijing Normal University, 100875 Beijing (China); Zeng, An, E-mail: anzeng@bnu.edu.cn [School of Systems Science, Beijing Normal University, 100875 Beijing (China)

    2017-01-30

    Cascading failure is an important process which has been widely used to model catastrophic events such as blackouts and financial crisis in real systems. However, so far most of the studies in the literature focus on the cascading process on nodes, leaving the possibility of link cascade overlooked. In many real cases, the catastrophic events are actually formed by the successive disappearance of links. Examples exist in the financial systems where the firms and banks (i.e. nodes) still exist but many financial trades (i.e. links) are gone during the crisis, and the air transportation systems where the airports (i.e. nodes) are still functional but many airlines (i.e. links) stop operating during bad weather. In this letter, we develop a link cascade model in complex networks. With this model, we find that both artificial and real networks tend to collapse even if a few links are initially attacked. However, the link cascading process can be effectively terminated by setting a few strong nodes in the network which do not respond to any link reduction. Finally, a simulated annealing algorithm is used to optimize the location of these strong nodes, which significantly improves the robustness of the networks against the link cascade. - Highlights: • We propose a link cascade model in complex networks. • Both artificial and real networks tend to collapse even if a few links are initially attacked. • The link cascading process can be effectively terminated by setting a few strong nodes. • A simulated annealing algorithm is used to optimize the location of these strong nodes.

  8. Cascade Textures and SUSY SO(10) GUT

    CERN Document Server

    Adulpravitchai, Adisorn; Takahashi, Ryo

    2010-01-01

    We give texture analyses of cascade hierarchical mass matrices in supersymmetric SO(10) grand unified theory. We embed cascade mass textures of the standard model fermion with right-handed neutrinos into the theory, which gives relations among the mass matrices of the fermions. The related phenomenologies, such as the lepton flavor violating processes and leptogenesis, are also investigated in addition to the PMNS mixing angles.

  9. Detailed comparison between parton cascade and hadronic cascade at SPS and RHIC

    CERN Document Server

    Nara, Y; Longacre, R S

    1999-01-01

    We study the importance of the partonic phase produced in relativistic heavy ion collision by comparing the parton cascade model and the hadronic cascade model. Hadron yield, baryon stopping and transverse momentum distribution are calculated with JAM and discussions are given comparing with VNI. Both of these models give good description of experimental data. We also discuss the strangeness production mechanism and the directed transverse flow. (21 refs).

  10. A Developmental Model of Reading Acquisition Based upon Early Scaffolding Errors and Subsequent Vowel Inferences

    Science.gov (United States)

    Savage, Robert; Stuart, Morag

    2006-01-01

    This paper investigates the processes that predict reading acquisition. Associations between (a) scaffolding errors (e.g., "torn" misread as "town" or "tarn"), other reading errors, and later reading and (b) vowel and rime inferences and later reading were explored. To assess both of these issues, 50 6-year-old children were shown a number of CVC…

  11. Multiple Regression Analysis of Reading Performance Data from Twin Pairs with Reading Difficulties and Non-twin Siblings: The Augmented Model

    OpenAIRE

    Wadsworth, S J; Olson, R. K.; Willcutt, E.G.; DeFries, J. C.

    2012-01-01

    The augmented multiple regression model for the analysis of data from selected twin pairs was extended to facilitate analyses of data from twin pairs and non-twin siblings. Fitting this extended model to data from both selected twin pairs and siblings yields direct estimates of heritability (h2) and the difference between environmental influences shared by members of twin pairs and those of sib or twin/sib pairs [i.e., c2(t) − c2(s)]. When this model was fitted to reading performance data fro...

  12. Training Inference Making Skills Using a Situation Model Approach Improves Reading Comprehension

    Directory of Open Access Journals (Sweden)

    Lisanne eBos

    2016-02-01

    Full Text Available This study aimed to enhance third and fourth graders’ text comprehension at the situation model level. Therefore, we tested a reading strategy training developed to target inference making skills, which are widely considered to be pivotal to situation model construction. The training was grounded in contemporary literature on situation model-based inference making and addressed the source (text-based versus knowledge-based, type (necessary versus unnecessary for (re-establishing coherence, and depth of an inference (making single lexical inferences versus combining multiple lexical inferences, as well as the type of searching strategy (forward versus backward. Results indicated that, compared to a control group (n = 51, children who followed the experimental training (n = 67 improved their inference making skills supportive to situation model construction. Importantly, our training also resulted in increased levels of general reading comprehension and motivation. In sum, this study showed that a ‘level of text representation’-approach can provide a useful framework to teach inference making skills to third and fourth graders.

  13. Training Inference Making Skills Using a Situation Model Approach Improves Reading Comprehension.

    Science.gov (United States)

    Bos, Lisanne T; De Koning, Bjorn B; Wassenburg, Stephanie I; van der Schoot, Menno

    2016-01-01

    This study aimed to enhance third and fourth graders' text comprehension at the situation model level. Therefore, we tested a reading strategy training developed to target inference making skills, which are widely considered to be pivotal to situation model construction. The training was grounded in contemporary literature on situation model-based inference making and addressed the source (text-based versus knowledge-based), type (necessary versus unnecessary for (re-)establishing coherence), and depth of an inference (making single lexical inferences versus combining multiple lexical inferences), as well as the type of searching strategy (forward versus backward). Results indicated that, compared to a control group (n = 51), children who followed the experimental training (n = 67) improved their inference making skills supportive to situation model construction. Importantly, our training also resulted in increased levels of general reading comprehension and motivation. In sum, this study showed that a 'level of text representation'-approach can provide a useful framework to teach inference making skills to third and fourth graders.

  14. Reading materials for post-literacy: The development and testing of a model of social writing

    Science.gov (United States)

    Bhola, Harbans S.

    1989-12-01

    A model of social writing, for use in writing socially relevant, easy-to-read, follow-up books for neo-literate adults, is presented. The model was fully developed and tested in the context of a series of writers' workshops during 1981-87; and incorporates all of the three aspects of writing: the expressive, the cognitive, and the social. Specifically, the following elements are included: selection of subject and topic within a dialectic of national development needs and community learning needs; negotiable definitions of general and specific objectives; acquiring knowledge of subject matter, and establishing necessary collaboration with subject-matter specialists; content planning to choose content and language of discourse, participatively with the future community of readers; choice of treatment of content as didactic or dramatic; outlining of manuscript as argument, dialogue or story; writing easy-to-read yet interesting materials; trying out the manuscript and making revisions; working with the illustrator and the editor; and preparing the manuscript for printing. Both the development and the testing of the model involved reflection-in-action and not stand-alone research exercises. The successful use of the model in workshops to train writers of post-literacy materials provided one source of support for the model. A comparison of this model of social writing with other models of writing available in literature has provided further support for the conceptual and procedural structure of the model. Transfers of the model to other cultural settings as well as to the writing of other types of educational materials, such as distance education texts and units, have also proved effective.

  15. Transport properties of cascading gauge theories

    CERN Document Server

    Buchel, A

    2005-01-01

    Cascading gauge theories of Klebanov et.al. provide a model within a framework of gauge theory/string theory duality for a four dimensional non-conformal gauge theory with a spontaneously generated mass scale. Using the dual supergravity description we study sound wave propagation in strongly coupled cascading gauge theory plasma. We analytically compute the speed of sound and the bulk viscosity of cascading gauge theory plasma at a temperature much larger than the strong coupling scale of the theory. The sound wave dispersion relation is obtained from the hydrodynamic pole in the stress-energy tensor two-point correlation function. The speed of sound extracted from the pole of the correlation function agrees with its value computed in [hep-th/0506002] using the equation of state. We find that the bulk viscosity of the hot cascading gauge theory plasma is non-zero at the leading order in the deviation from conformality.

  16. Cascade of period doublings of tori

    Science.gov (United States)

    Arneodo, A.; Coullet, P. H.; Spiegel, E. A.

    1983-02-01

    A three-dimensional map is proposed to model the effects of periodic forcing on a system displaying a transition to chaos through a cascade of period-doubling bifurcations. The study outlined here raises the problem of the existence and bifurcation of invariant tori. A principal feature of the simulations of both the differential equations and the discrete dynamical systems is that it is possible to disrupt period-doubling sequences (and inverse sequences as well) by periodic external forcing. Even though the way in which this abortion works is not understood, the mechanism is thought to be associated with the destruction of tori (Aronson et al., 1982) when the system is on the verge of bifurcation. The simulations therefore suggest that in moving farther along the cascade, the tori become more fragile. It is suspected that for arbitrarily weak driving, the cascade will eventually be disrupted after the cascade has proceeded through a sufficient number of steps.

  17. The fictionality of topic modeling: Machine reading Anthony Trollope's Barsetshire series

    Directory of Open Access Journals (Sweden)

    Rachel Sagner Buurma

    2015-12-01

    Full Text Available This essay describes how using unsupervised topic modeling (specifically the latent Dirichlet allocation topic modeling algorithm in MALLET on relatively small corpuses can help scholars of literature circumvent the limitations of some existing theories of the novel. Using an example drawn from work on Victorian novelist Anthony Trollope's Barsetshire series, it argues that unsupervised topic modeling's counter-factual and retrospective reconstruction of the topics out of which a given set of novels have been created allows for a denaturalizing and unfamiliar (though crucially not “objective” or “unbiased” view. In other words, topic models are fictions, and scholars of literature should consider reading them as such. Drawing on one aspect of Stephen Ramsay's idea of algorithmic criticism, the essay emphasizes the continuities between “big data” methods and techniques and longer-standing methods of literary study.

  18. Cascade-exciton model analysis of level density parameter dependence in proton induced fission cross sections of some sub-actinide nuclei

    Institute of Scientific and Technical Information of China (English)

    Zafar Yasin; Warda Iram; Muhammad Asghar; M. Ikram Shahzad

    2011-01-01

    Fission cross sections strongly depend on the ratio of the level density parameter in fission to neutron emission,af/an.In this work,a cascade-exciton model implemented in the code CEM95 has been used to observe this effect for proton induced fission cross sections of tungsten,lead and bismuth.The method was employed using different level density parameter ratios for each fission cross section calculation.The calculated fission cross sections are compared with the available experimental data in the literature.It has been observed that a change of the ratio of the level density parameter,af/an,is necessary with the incident energy of the proton,to best estimate the fission cross sections in CEM95.

  19. Trophic cascades of bottom-up and top-down forcing on nutrients and plankton in the Kattegat, evaluated by modelling

    DEFF Research Database (Denmark)

    Petersen, Marcell Elo; Maar, Marie; Larsen, Janus

    2017-01-01

    The aim of the study was to investigate the relative importance of bottom-up and top-down forcing on trophic cascades in the pelagic food-web and the implications for water quality indicators (summer phytoplankton biomass and winter nutrients) in relation to management. The 3D ecological model....... On annual basis, the system was more bottom-up than top-down controlled. Microzooplankton was found to play an important role in the pelagic food web as mediator of nutrient and energy fluxes. This study demonstrated that the best scenario for improved water quality was a combined reduction in nutrient...... input and mesozooplankton mortality calling for the need of an integrated management of marine areas exploited by human activities....

  20. Modeling and Design of Five Level Cascaded H-Bridge Multilevel Inverter with DC/DC Boost Converter

    Directory of Open Access Journals (Sweden)

    Vinayaka B.C

    2014-06-01

    Full Text Available Power electronic converters, especially DC/AC Sinusoidal Pulse Width Modulation inverters have been extending their range of use in industry because of their numerous advantages. They typically synthesize the stair –case voltage waveform (from several dc sources which has reduced harmonic content. This paper aims to extend the knowledge about the performance of Five level Cascaded H-Bridge MLI topology with DC/DC Boost Converter using SPWM for fixed DC Source. The output voltage is the sum of the voltage that is generated by each bridge. The switching angles can be chosen in such a way that the total harmonic distortion is minimized. This topology incorporates Boost Converter in the input side which magnifies the fundamental output voltage with reduction in total harmonic distortion. It also incorporates LC filter and hence output is drawn near the sine wave because of more levels. Results of experiments proved efficiency of 95%.The performance of the proposed SPWM strategy in terms of output voltage and THD has studied successfully and shown using MATLAB/Simulink.

  1. The Effects of Blended Instruction on Oral Reading Performance and their Relationships to a Five-Factor Model of Personality

    Directory of Open Access Journals (Sweden)

    Isao Miyaji

    2010-09-01

    Full Text Available In recent times, 'Blended Instruction' - an effective method of instructions utilizing e-Learning materials in English education - consists of an individual learning part, a collaborative learning part and a teacher instruction part. In the individual learning, students act out model dialogues in the WBT courseware which incorporated a high quantity of video and sound clips. In the collaborative learning, students perform the dialogues in pairs and assessed each other's performance. Our recent research in a high school showed that the skill of the students' oral reading was improved in most criteria of assessment through blended instruction. However, it is still not clear what kind of relationship exists between the development of the students' oral reading skills and their personalities. With this in mind, the authors have studied the effects of the blended instruction on the junior high school students' oral reading performance and their relationships to the five-factor model of personality. The result of the research shows that the skill of the students' oral reading was improved in most criteria of assessment and the blended instruction was effective for the personality group, 'Introverted unintelligent person' in the most categories of oral reading criteria as well as the personality group, 'Sociable hard-worker'. The important factor for that group in oral reading performance turned out to be 'Sense Reading'.

  2. Experiences in Reading Instruction as the Road to Teaching Reading.

    Science.gov (United States)

    Corlett, Donna Jean

    1988-01-01

    Describes a model self-improvement reading course for teachers incorporating the communications model, the skills model, and the sustained silent reading model. Concludes that basic reading skills instruction led to improvement in reading skills and that lesson plans incorporating course objectives were produced. (RS)

  3. Do Dual-Route Models Accurately Predict Reading and Spelling Performance in Individuals with Acquired Alexia and Agraphia?

    Science.gov (United States)

    Rapcsak, Steven Z.; Henry, Maya L.; Teague, Sommer L.; Carnahan, Susan D.; Beeson, Pélagie M.

    2007-01-01

    Coltheart and colleagues (Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001; Castles, Bates, & Coltheart, 2006) have demonstrated that an equation derived from dual-route theory accurately predicts reading performance in young normal readers and in children with reading impairment due to developmental dyslexia or stroke. In this paper we present evidence that the dual-route equation and a related multiple regression model also accurately predict both reading and spelling performance in adult neurological patients with acquired alexia and agraphia. These findings provide empirical support for dual-route theories of written language processing. PMID:17482218

  4. iCRESLIDE: Integration of Coupled Routing and Excess Storage and SLope-Infiltration-Distributed Equilibrium for the Cascading Hydrologic-Geotechnical Modeling

    Science.gov (United States)

    Hong, Y.; Zhang, K.; Gourley, J. J.

    2015-12-01

    Floods and landslides account for the large number of natural hazards and affect more people than many other types of natural disasters around the world. This study proposed a coupled hydrological-geotechnical model iCRESLIDE (Integration of Coupled Routing and Excess Storage and SLope-Infiltration-Distributed Equilibrium). The iCRESLIDE is designed to remedy the discrepancy of the original landslide model (SLIDE) by coupling with a hydrological model (CREST) and building an integrated system for predicting cascading storm-flood-landslides using remote sensing and geospatial datasets. This coupled system is implemented and evaluated in Macon County, North Carolina, where Hurricane Ivan triggered widespread landslides in September 2004 during the hurricane season. Model simulations from iCRESLIDE show its reliability to predict landslides occurrence (location and time). Receiver Operating Characteristic (ROC) analysis demonstrate that the iCRESLIDE has higher global accuracy (0.750) and higher sensitivity (11.36%) compared to the original SLIDE model. Such improved predictive performance demonstrates the advantage of coupling hydrological-geotechnical models, which calls more attentions and deserves further investigations in order to develop a not only geotechnical sound but also hydrological sensitive system for landslides early warning at regional scale. This talk will also present early results of the NFL (National-Flash-Landslide) Monitoring and Prediction system under development at the NOAA/OU National Weather Center.

  5. Turbulence: does energy cascade exist?

    CERN Document Server

    Josserand, Christophe; Lehner, Thierry; Pomeau, Yves

    2016-01-01

    To answer the question whether a cascade of energy exists or not in turbulence, we propose a set of correlation functions able to test if there is an irreversible transfert of energy, step by step, from large to small structures. These tests are applied to real Eulerian data of a turbulent velocity flow, taken in the wind grid tunnel of Modane, and also to a prototype model equation for wave turbulence. First we demonstrate the irreversible character of the flow by using multi-time correlation function at a given point of space. Moreover the unexpected behavior of the test function leads us to connect irreversibility and finite time singularities (intermittency). Secondly we show that turbulent cascade exists, and is a dynamical process, by using a test function depending on time and frequency. The cascade shows up only in the inertial domain where the kinetic energy is transferred more rapidly (on average) from the wavenumber $k_{1}$ to $k_{2}$ than from $k_{1}$ to $k'_{2}$ larger than $k_{2}$.

  6. Reading The Sun: A Three Dimensional Visual Model of The Solar Environment During Solar Cycle 24

    Science.gov (United States)

    Carranza-fulmer, T. L.; Moldwin, M.

    2014-12-01

    The sun is a powerful force that has proven to our society that it has a large impact on our lives. Unfortunately, there is still a lack of awareness on how the sun is capable of affecting Earth. The over all idea of "Reading The Sun" installation is to help demonstrate how the sun impacts the Earth, by compiling various data sources from satellites (SOHO, SDO, and STERO) with solar and solar wind models (MAS and ENLIL) to create a comprehensive three dimensional display of the solar environment. It focuses on the current solar maximum of solar cycle 24 and a CME that impacted Earth's magnetic field on February 27, 2014, which triggered geomagnetic storms around the Earth's poles. The CME was an after-effect of a class X4.9 solar flare, which was released from the sun on February 25, 2014. "Reading The Sun" is a 48" x 48" x 48" hanging model of the sun with color coded open opposing magnetic field lines along with various layers of the solar atmosphere, the heliospheric current sheet, and the inner planets. At the center of the xyz axis is the sun with the open magnetic field lines and the heliospheric current sheet permeating inner planetary space. The xyz axes are color coded to represent various types of information with corresponding visual images for the viewer to be able to read the model. Along the z-axis are three colors (yellow, orange, and green) that represent the different layers of the solar atmosphere (photosphere, chromosphere, and corona) that correspond to three satellite images in various spectrums related to a CME and Solar Flare and the xy-plane shows where the inner planets are in relation to the sun. The exhibit in which "Reading The Sun "is being displayed is called, The Rotation of Language at the Wheather Again Gallery in Rockaway, New York. The intent of the exhibit is to both celebrate as well as present a cautionary tale on the ability of human language to spark and ignite the individual and collective imagination towards an experience

  7. Cascade Organic Solar Cells

    KAUST Repository

    Schlenker, Cody W.

    2011-09-27

    We demonstrate planar organic solar cells consisting of a series of complementary donor materials with cascading exciton energies, incorporated in the following structure: glass/indium-tin-oxide/donor cascade/C 60/bathocuproine/Al. Using a tetracene layer grown in a descending energy cascade on 5,6-diphenyl-tetracene and capped with 5,6,11,12-tetraphenyl- tetracene, where the accessibility of the π-system in each material is expected to influence the rate of parasitic carrier leakage and charge recombination at the donor/acceptor interface, we observe an increase in open circuit voltage (Voc) of approximately 40% (corresponding to a change of +200 mV) compared to that of a single tetracene donor. Little change is observed in other parameters such as fill factor and short circuit current density (FF = 0.50 ± 0.02 and Jsc = 2.55 ± 0.23 mA/cm2) compared to those of the control tetracene-C60 solar cells (FF = 0.54 ± 0.02 and Jsc = 2.86 ± 0.23 mA/cm2). We demonstrate that this cascade architecture is effective in reducing losses due to polaron pair recombination at donor-acceptor interfaces, while enhancing spectral coverage, resulting in a substantial increase in the power conversion efficiency for cascade organic photovoltaic cells compared to tetracene and pentacene based devices with a single donor layer. © 2011 American Chemical Society.

  8. Signal Modulation of Super Read Only Memory with Thermally Activated Aperture Model

    Science.gov (United States)

    Kim, June Seo; Kwak, Keumcheol; You, Chun-Yeol

    2008-07-01

    We describe the signal modulation of super read only memory (ROM) with thermally activated aperture model using a three-dimensional finite-difference time-domain method. The thermally activated aperture is modeled using a spatially varied refractive indices of the GeSbTe layer. No meaningful signal modulation is observed without thermally activated aperture below the resolution limit of 120 nm. When we open the thermally activated aperture by considering the temperature dependence of the refractive indices in the GeSbTe layer, the 2.8 and 1.7% signal modulations are observed for 120 and 80 nm pits, respectively. The experimentally observed signal modulation under the resolution limit can be explained using the thermally activated aperture model.

  9. A Multiple Deficit Model of Reading Disability and Attention-Deficit/Hyperactivity Disorder: Searching for Shared Cognitive Deficits

    Science.gov (United States)

    McGrath, Lauren M.; Pennington, Bruce F.; Shanahan, Michelle A.; Santerre-Lemmon, Laura E.; Barnard, Holly D.; Willcutt, Erik G.; DeFries, John C.; Olson, Richard K.

    2011-01-01

    Background: This study tests a multiple cognitive deficit model of reading disability (RD), attention-deficit/hyperactivity disorder (ADHD), and their comorbidity. Methods: A structural equation model (SEM) of multiple cognitive risk factors and symptom outcome variables was constructed. The model included phonological awareness as a unique…

  10. The Relationship between Delivery Models and the Grade-Level Reading Development of Sixth-Grade English Learners

    Science.gov (United States)

    Arnold, Holly Weber

    2013-01-01

    This study examines the relationship between delivery models (the class size reduction model and the sheltered instruction model) and language development levels on the grade-level reading development of sixth-grade English learners (ELs) attending public middle schools in metro Atlanta, Georgia. The instrument used to measure grade-level mastery…

  11. Mathematical modelling and process optimization of a continuous 5-stage bioreactor cascade for production of poly[-(R)-3-hydroxybutyrate] by Cupriavidus necator.

    Science.gov (United States)

    Horvat, Predrag; Vrana Špoljarić, Ivna; Lopar, Markan; Atlić, Aid; Koller, Martin; Braunegg, Gerhart

    2013-09-01

    A multistage system for poly(hydroxyalkanoate) (PHA) production consisting of five continuous stirred tank reactors in series (5-CSTR) with Cupriavidus necator DSM 545 as production strain was modelled using formal kinetic relations. Partially growth-associated production of PHA under nitrogen limited growth was chosen as modelling strategy, thus the Luedeking-Piret's model of partial growth-associated product synthesis was applied as working hypothesis. Specific growth rate relations adjusted for double substrate (C and N source) limited growth according to Megee et al. and Mankad-Bungay relation were tested. The first stage of the reactor cascade was modelled according to the principle of nutrient balanced continuous biomass production system, the second one as two substrate controlled process, while the three subsequent reactors were adjusted to produce PHB under continuous C source fed and nitrogen deficiency. Simulated results of production obtained by the applied mathematical models and computational optimization indicate that PHB productivity of the whole system could be significantly increased (from experimentally achieved 2.14 g L(-1) h(-1) to simulated 9.95 g L(-1) h(-1)) if certain experimental conditions would have been applied (overall dilution rate, C and N source feed concentration). Additionally, supplemental feeding strategy for switching from batch to continuous mode of cultivation was proposed to avoid substrate inhibition.

  12. About Reading

    Institute of Scientific and Technical Information of China (English)

    独行墨客

    2004-01-01

    As for reading and for learning, reading rate (that is, words per minute, WPM) is important, especially for students who have to pass some reading test. How to compute your reading rate? You may know it after reading the following. Reading Rate (WPM) = Total number of words + reading time.

  13. Author’s response: A universal approach to modeling visual word recognition and reading: not only possible, but also inevitable.

    Science.gov (United States)

    Frost, Ram

    2012-10-01

    I have argued that orthographic processing cannot be understood and modeled without considering the manner in which orthographic structure represents phonological, semantic, and morphological information in a given writing system. A reading theory, therefore, must be a theory of the interaction of the reader with his/her linguistic environment. This outlines a novel approach to studying and modeling visual word recognition, an approach that focuses on the common cognitive principles involved in processing printed words across different writing systems. These claims were challenged by several commentaries that contested the merits of my general theoretical agenda, the relevance of the evolution of writing systems, and the plausibility of finding commonalities in reading across orthographies. Other commentaries extended the scope of the debate by bringing into the discussion additional perspectives. My response addresses all these issues. By considering the constraints of neurobiology on modeling reading, developmental data, and a large scope of cross-linguistic evidence, I argue that front-end implementations of orthographic processing that do not stem from a comprehensive theory of the complex information conveyed by writing systems do not present a viable approach for understanding reading. The common principles by which writing systems have evolved to represent orthographic, phonological, and semantic information in a language reveal the critical distributional characteristics of orthographic structure that govern reading behavior. Models of reading should thus be learning models, primarily constrained by cross-linguistic developmental evidence that describes how the statistical properties of writing systems shape the characteristics of orthographic processing. When this approach is adopted, a universal model of reading is possible.

  14. Critical Mandelbrot Cascades

    Science.gov (United States)

    Barral, Julien; Kupiainen, Antti; Nikula, Miika; Saksman, Eero; Webb, Christian

    2014-01-01

    We study Mandelbrot's multiplicative cascade measures at the critical temperature. As has been recently shown by Barral et al. (C R Acad Sci Paris Ser I 350:535-538, 2012), an appropriately normalized sequence of cascade measures converges weakly in probability to a nontrivial limit measure. We prove that these limit measures have no atoms and give bounds for the modulus of continuity of the cumulative distribution function of the measure. Using the earlier work of Barral and Seuret (Adv Math 214:437-468, 2007), we compute the multifractal spectrum of the measures. We also extend the result of Benjamini and Schramm (Commun Math Phys 289:653-662, 2009), in which the KPZ formula from quantum gravity is validated for the high temperature cascade measures, to the critical and low temperature cases.

  15. Multiple mediation path model of pain's cascading influence on physical disability in individuals with SCI from Colombia, South America.

    Science.gov (United States)

    Perrin, Paul B; Paredes, Alejandra Morlett; Olivera, Silvia Leonor; Lozano, Juan Esteban; Leal, Wendy Tatiana; Ahmad, Usman F; Arango-Lasprilla, Juan Carlos

    2017-01-01

    Research has begun to document the bivariate connections between pain in individuals with spinal cord injury (SCI) and various aspects of health related quality of life (HRQOL), such as fatigue, social functioning, mental health, and physical functioning. The purpose of this study was to construct and test a theoretical path model illuminating the stage-wise and sequential (cascading) HRQOL pathways through which pain increases physical disability in individuals with SCI in a sample from Colombia, South America. It was hypothesized that increased pain would lead to decreased energy, which would lead to decreased mental health and social functioning, which both would lead to emotional role limitations, which finally would lead to physical role limitations. A cross-sectional study assessed individuals with SCI (n = 40) in Neiva, Colombia. Participants completed a measure indexing various aspects of HRQOL. The path model overall showed excellent fit indices, and each individual path within the model was statistically significant. Pain exerted significant indirect effects through all possible mediators in the model, ultimately suggesting that energy, mental health, social functioning, and role limitations-emotional were likely pathways through which pain exerted its effects on physical disability in individuals with SCI. These findings uncover several potential nodes for clinical intervention which if targeted in the context of rehabilitation or outpatient services, could result in salubrious direct and indirect effects reverberating down the theoretical causal chain and ultimately reducing physical disability in individuals with SCI.

  16. Reading Ability Development from Kindergarten to Junior Secondary: Latent Transition Analyses with Growth Mixture Modeling

    Directory of Open Access Journals (Sweden)

    Yuan Liu

    2016-10-01

    Full Text Available The present study examined the reading ability development of children in the large scale Early Childhood Longitudinal Study (Kindergarten Class of 1998-99 data; Tourangeau, Nord, Lê, Pollack, & Atkins-Burnett, 2006 under the dynamic systems. To depict children's growth pattern, we extended the measurement part of latent transition analysis to the growth mixture model and found that the new model fitted the data well. Results also revealed that most of the children stayed in the same ability group with few cross-level changes in their classes. After adding the environmental factors as predictors, analyses showed that children receiving higher teachers' ratings, with higher socioeconomic status, and of above average poverty status, would have higher probability to transit into the higher ability group.

  17. The Relation between Morphological Awareness and Reading Comprehension: Evidence from Mediation and Longitudinal Models

    Science.gov (United States)

    Deacon, S. Hélène; Kieffer, Michael J.; Laroche, Annie

    2014-01-01

    We examined the role of a hypothesized factor in reading comprehension: morphological awareness, or the awareness of and ability to manipulate the smallest meaningful units or morphemes. In this longitudinal study, we measured English-speaking children's morphological awareness, word reading skills, and reading comprehension at Grades 3 and 4, in…

  18. The Relation between Morphological Awareness and Reading Comprehension: Evidence from Mediation and Longitudinal Models

    Science.gov (United States)

    Deacon, S. Hélène; Kieffer, Michael J.; Laroche, Annie

    2014-01-01

    We examined the role of a hypothesized factor in reading comprehension: morphological awareness, or the awareness of and ability to manipulate the smallest meaningful units or morphemes. In this longitudinal study, we measured English-speaking children's morphological awareness, word reading skills, and reading comprehension at Grades 3 and 4, in…

  19. The Collaboration Model and Reading Improvement of High School Students with Learning Disabilities

    Science.gov (United States)

    Sacchetto, Jorge A.

    2014-01-01

    In the field of reading research, studies focusing on improvement of a high school student's reading achievements are lacking. Collaborative interventions for reading instruction are useful and more prevalent for elementary age students but not high school students. Therefore, there remains an important gap in the current literature regarding…

  20. Towards a Dynamic Model of Skills Involved in Sight Reading Music

    Science.gov (United States)

    Kopiez, Reinhard; Lee, Ji In

    2006-01-01

    This study investigates the relationship between selected predictors of achievement in playing unrehearsed music (sight reading) and the changing complexity of sight reading tasks. The question under investigation is, how different variables gain or lose significance as sight reading stimuli become more difficult. Fifty-two piano major graduates…

  1. Metrological Traceability in the Social Sciences: A Model from Reading Measurement

    Science.gov (United States)

    Stenner, A. Jackson; Fisher, William P., Jr.

    2013-09-01

    The central importance of reading ability in learning makes it the natural place to start in formative and summative assessments in education. The Lexile Framework for Reading constitutes a commercial metrological traceability network linking books, test results, instructional materials, and students in elementary and secondary English and Spanish language reading education in the U.S., Canada, Mexico, and Australia.

  2. Modeling Local Item Dependence in Cloze and Reading Comprehension Test Items Using Testlet Response Theory

    Science.gov (United States)

    Baghaei, Purya; Ravand, Hamdollah

    2016-01-01

    In this study the magnitudes of local dependence generated by cloze test items and reading comprehension items were compared and their impact on parameter estimates and test precision was investigated. An advanced English as a foreign language reading comprehension test containing three reading passages and a cloze test was analyzed with a…

  3. Reading Logs and Literature Teaching Models in English Language Teacher Education

    Science.gov (United States)

    Ochoa Delarriva, Ornella; Basabe, Enrique Alejandro

    2016-01-01

    Reading logs are regularly used in foreign language education since they are not only critical in the development of reading comprehension but may also be instrumental in taking readers beyond the referential into the representational realms of language. In this paper we offer the results of a qualitative analysis of a series of reading logs…

  4. Forecasting Reading Anxiety for Promoting English-Language Reading Performance Based on Reading Annotation Behavior

    Science.gov (United States)

    Chen, Chih-Ming; Wang, Jung-Ying; Chen, Yong-Ting; Wu, Jhih-Hao

    2016-01-01

    To reduce effectively the reading anxiety of learners while reading English articles, a C4.5 decision tree, a widely used data mining technique, was used to develop a personalized reading anxiety prediction model (PRAPM) based on individual learners' reading annotation behavior in a collaborative digital reading annotation system (CDRAS). In…

  5. Role of Reading Engagement in Mediating Effects of Reading Comprehension Instruction on Reading Outcomes

    Science.gov (United States)

    Wigfield, Allan; Guthrie, John T.; Perencevich, Kathleen C.; Taboada, Ana; Klauda, Susan Lutz; McRae, Angela; Barbosa, Pedro

    2008-01-01

    The engagement model of reading development suggests that instruction improves students' reading comprehension to the extent that it increases students' engagement processes in reading. We compared how Concept-Oriented Reading Instruction (CORI) (support for cognitive and motivational processes in reading), strategy instruction (support for…

  6. Tone matters for Cantonese-English bilingual children's English word reading development: A unified model of phonological transfer.

    Science.gov (United States)

    Tong, Xiuli; He, Xinjie; Deacon, S Hélène

    2017-02-01

    Languages differ considerably in how they use prosodic features, or variations in pitch, duration, and intensity, to distinguish one word from another. Prosodic features include lexical tone in Chinese and lexical stress in English. Recent cross-sectional studies show a surprising result that Mandarin Chinese tone sensitivity is related to Mandarin-English bilingual children's English word reading. This study explores the mechanism underlying this relation by testing two explanations of these effects: the prosodic hypothesis and segmental phonological awareness transfer. We administered multiple measures of Cantonese tone sensitivity, English stress sensitivity, segmental phonological awareness in Cantonese and English, nonverbal ability, and English word reading to 123 Cantonese-English bilingual children ages 7 and 8 years. Structural equation modeling revealed a longitudinal prediction of Cantonese tone sensitivity to English word reading between 8 and 9 years of age. This relation was realized through two parallel routes. In one, Cantonese tone sensitivity predicted English stress sensitivity, and English stress sensitivity, in turn, significantly predicted English word reading, as postulated by the prosodic hypothesis. In the second, Cantonese tone sensitivity predicted English word reading through the transfer of segmental phonological awareness between Cantonese and English, as predicted by segmental phonological transfer. These results support a unified model of phonological transfer, emphasizing the role of tone in English word reading for Cantonese-English bilingual children.

  7. Interband Cascade Photovoltaic Cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui Q. [Univ. of Oklahoma, Norman, OK (United States); Santos, Michael B. [Univ. of Oklahoma, Norman, OK (United States); Johnson, Matthew B. [Univ. of Oklahoma, Norman, OK (United States)

    2014-09-24

    In this project, we are performing basic and applied research to systematically investigate our newly proposed interband cascade (IC) photovoltaic (PV) cells [1]. These cells follow from the great success of infrared IC lasers [2-3] that pioneered the use of quantum-engineered IC structures. This quantum-engineered approach will enable PV cells to efficiently convert infrared radiation from the sun or other heat source, to electricity. Such cells will have important applications for more efficient use of solar energy, waste-heat recovery, and power beaming in combination with mid-infrared lasers. The objectives of our investigations are to: achieve extensive understanding of the fundamental aspects of the proposed PV structures, develop the necessary knowledge for making such IC PV cells, and demonstrate prototype working PV cells. This research will focus on IC PV structures and their segments for utilizing infrared radiation with wavelengths from 2 to 5 μm, a range well suited for emission by heat sources (1,000-2,000 K) that are widely available from combustion systems. The long-term goal of this project is to push PV technology to longer wavelengths, allowing for relatively low-temperature thermal sources. Our investigations address material quality, electrical and optical properties, and their interplay for the different regions of an IC PV structure. The tasks involve: design, modeling and optimization of IC PV structures, molecular beam epitaxial growth of PV structures and relevant segments, material characterization, prototype device fabrication and testing. At the end of this program, we expect to generate new cutting-edge knowledge in the design and understanding of quantum-engineered semiconductor structures, and demonstrate the concepts for IC PV devices with high conversion efficiencies.

  8. 通过构建主题立体阅读模式提升学生阅读素养%Improvement of Students’ Reading Literacy through the Construction of Theme Stereo Reading Model

    Institute of Scientific and Technical Information of China (English)

    金银琴

    2014-01-01

    阅读是提高大学生素质的重要途径,主题立体阅读是一种创新型的导读模式。图书馆联合学校多个部门建立导读机构,以主题为核心,整合各方资源,制定统一的导读方案,通过平面海报、专题网站、阅读博客、手机信息、广播等立体宣传和好书推荐、主题展览、阅读讲座、电影观摩、汇报演出、竞赛活动、读书沙龙等活动形式,将传统单一、静态、灌输式的导读方式转化为立体多元、互动、学生主动探寻的导读方式,激发学生的阅读兴趣,提升学生的阅读素养。%Reading is an important way to improve college students’ literacy, and the stereo theme reading is an innovative reading guidance model. The library should establish a reading guidance institution with other departments of university, take the theme as the core, integrate all resources, make a unified reading guidance plan, and change the reading guidance model from the traditional, single, static, inculcation-based model into the stereo, interactive and initiative model through the stereo propaganda such as the plane posters, special website, blog reading, mobile information, broadcasting, etc. and activities such as the good book recommendation, theme exhibition, reading lecture, movie watching, report-back performances, competition, and reading salon, etc., so as to stimulate students’ reading interest and improve their reading literacy.

  9. Influence of blood flow on the coagulation cascade

    DEFF Research Database (Denmark)

    The influence of diffusion and convetive flows on the blood coagulation cascade is investigated for a controlled perfusion experiment. We present a cartoon model and reaction schemes for parts of the coagulation cascade with sunsequent set up of a mathematical model in two space dimensions plus one...

  10. Model -free adaptive control for cascade industrial nonlinear system%工业串联非线性系统无模型自适应控制

    Institute of Scientific and Technical Information of China (English)

    胡元胜; 张广林; 刘超; 张永亮

    2011-01-01

    A model - free adaptive control algorithm for cascade industrial nonlinear system is proposed. The controller is designed only by using I/O data of the controlled system, and the model of the controlled system is not necessary. The impact of the unmodelled dynamics of the process model is not exist. Simulation result shows that the proposed method is an effective algorithm with excellent tracking a-bility and strong robustness.%针对实际工业生产过程中存在的大量串联非线性系统,提出了一种基于紧格式线性化的串联非线性系统无模型自适应控制算法.该算法无需建立被控对象数学模型,仅用输入输出数据来设计控制器,有效避免了非建模动态问题.仿真结果表明该算法具有较强的跟踪性能和鲁棒性.

  11. Unraveling low-resolution structural data of large biomolecules by constructing atomic models with experiment-targeted parallel cascade selection simulations

    Science.gov (United States)

    Peng, Junhui; Zhang, Zhiyong

    2016-07-01

    Various low-resolution experimental techniques have gained more and more popularity in obtaining structural information of large biomolecules. In order to interpret the low-resolution structural data properly, one may need to construct an atomic model of the biomolecule by fitting the data using computer simulations. Here we develop, to our knowledge, a new computational tool for such integrative modeling by taking the advantage of an efficient sampling technique called parallel cascade selection (PaCS) simulation. For given low-resolution structural data, this PaCS-Fit method converts it into a scoring function. After an initial simulation starting from a known structure of the biomolecule, the scoring function is used to pick conformations for next cycle of multiple independent simulations. By this iterative screening-after-sampling strategy, the biomolecule may be driven towards a conformation that fits well with the low-resolution data. Our method has been validated using three proteins with small-angle X-ray scattering data and two proteins with electron microscopy data. In all benchmark tests, high-quality atomic models, with generally 1-3 Å from the target structures, are obtained. Since our tool does not need to add any biasing potential in the simulations to deform the structure, any type of low-resolution data can be implemented conveniently.

  12. Application of Density Functional Theoretic Descriptors to Quantitative Structure-Activity Relationships with Temperature Constrained Cascade Correlation Network Models of Nitrobenzene Derivatives

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A temperature-constrained cascade correlation network(TCCCN), a back-propagation neural network(BP), and multiple linear regression(MLR) models were applied to quantitative structure-activity relationship(QSAR) modeling, on the basis of a set of 35 nitrobenzene derivatives and their acute toxicities. These structural quantum-chemical descriptors were obtained from the density functional theory(DFT). Stepwise multiple regression analysis was performed and the model was obtained. The value of the calibration correlation coefficient R is 0.925, and the value of cross-validation correlation coefficient R is 0.87. The standard error S=0.308 and the cross-validated(leave-one-out) standard error Scv=0.381. Principal component analysis(PCA) was carried out for parameter selection. RMS errors for training set via TCCCN and BP are 0.067 and 0.095, respectively, and RMS errors for testing set via TCCCN and BP are 0.090 and 0.111, respectively. The results show that TCCCN performs better than BP and MLR.

  13. Evaluation of Two Soil Water Redistribution Models (Finite Difference and Hourly Cascade Approach) Through The Comparison of Continuous field Sensor-Based Measurements

    Science.gov (United States)

    Ferreyra, R.; Stockle, C. O.; Huggins, D. R.

    2014-12-01

    Soil water storage and dynamics are of critical importance for a variety of processes in terrestrial ecosystems, including agriculture. Many of those systems are under significant pressure in terms of water availability and use. Therefore, assessing alternative scenarios through hydrological models is an increasingly valuable exercise. Soil water holding capacity is defined by the concepts of soil field capacity and plant available water, which are directly related to soil physical properties. Both concepts define the energy status of water in the root system and closely interact with plant physiological processes. Furthermore, these concepts play a key role in the environmental transport of nutrients and pollutants. Soil physical parameters (e.g. saturated hydraulic conductivity, total porosity and water release curve) are required as input for field-scale soil water redistribution models. These parameters are normally not easy to measure or monitor, and estimation through pedotransfer functions is often inadequate. Our objectives are to improve field-scale hydrological modeling by: (1) assessing new undisturbed methodologies for determining important soil physical parameters necessary for model inputs; and (2) evaluating model outputs, making a detailed specification of soil parameters and the particular boundary condition that are driving water movement under two contrasting environments. Soil physical properties (saturated hydraulic conductivity and determination of water release curves) were quantified using undisturbed laboratory methodologies for two different soil textural classes (silt loam and sandy loam) and used to evaluate two soil water redistribution models (finite difference solution and hourly cascade approach). We will report on model corroboration results performed using in situ, continuous, field measurements with soil water content capacitance probes and digital tensiometers. Here, natural drainage and water redistribution were monitored

  14. Cascaded Poisson processes

    Science.gov (United States)

    Matsuo, Kuniaki; Saleh, Bahaa E. A.; Teich, Malvin Carl

    1982-12-01

    We investigate the counting statistics for stationary and nonstationary cascaded Poisson processes. A simple equation is obtained for the variance-to-mean ratio in the limit of long counting times. Explicit expressions for the forward-recurrence and inter-event-time probability density functions are also obtained. The results are expected to be of use in a number of areas of physics.

  15. Examining the Relationship between Middle School Students' Critical Reading Skills, Science Literacy Skills and Attitudes: A Structural Equation Modeling

    Science.gov (United States)

    Karademir, Ersin; Ulucinar, Ufuk

    2017-01-01

    The purpose of this study is to verify the causal relationship between middle school students' critical reading skills, science literacy skills and attitudes towards science literacy with research data according to the default model. Through the structural equation modeling, path analysis has been applied in the study which was designed in…

  16. Reading, Perceptual Strategies and Contrastive Analysis

    Science.gov (United States)

    Cowan, J. Ronayne

    1976-01-01

    Analyzes syntactic processes in three learning situations, Japanese reading English, Persians reading English and English speakers reading Hindi; discussed in terms of reading process and second language learning models. (Author/RM)

  17. Integrated Broadband Quantum Cascade Laser

    Science.gov (United States)

    Mansour, Kamjou (Inventor); Soibel, Alexander (Inventor)

    2016-01-01

    A broadband, integrated quantum cascade laser is disclosed, comprising ridge waveguide quantum cascade lasers formed by applying standard semiconductor process techniques to a monolithic structure of alternating layers of claddings and active region layers. The resulting ridge waveguide quantum cascade lasers may be individually controlled by independent voltage potentials, resulting in control of the overall spectrum of the integrated quantum cascade laser source. Other embodiments are described and claimed.

  18. Simulated nucleon–nucleon and nucleon–nucleus reactions in the frame of the cascade exciton model at high and intermediate energies

    Indian Academy of Sciences (India)

    A Abdel-Hafiez; Shaker El-Shater; M F Zaki

    2015-04-01

    In this study, we have used the cascade exciton model (CEM) to investigate different characteristics of nuclear reactions. Number of nucleon–nucleon collisions in Pb+Pb collisions as a function of impact parameter and rapidity distributions of negative particles from p+Ar and p+Xe interactions at lab = 200 GeV/c have been studied. We could create inclusive spectra of pions for separate charged states from reactions and total neutron multiplicities per primary reaction at 1000 MeV for different thin targets. Also, cross-sections for the reactions 209Bi(p, f) and 209Bi(n, f) were studied. Interactions of 1.0 GeV protons with C, Al, Cu, Sn, and Pb are presented in this study. All the calculated characteristics are compared with other theoretical calculations and compared with the experimental data. CEM shows good agreement with both theoretical and experimental results. In this study, we have used quantum molecular dynamic (QMD) as a theoretical model to compare our results.

  19. Changes in reading strategies in school-age children.

    Science.gov (United States)

    Sanabria Díaz, Gretel; Torres, María del Rosario; Iglesias, Jorge; Mosquera, Raysil; Reigosa, Vivian; Santos, Elsa; Lage, Agustín; Estévez, Nancy; Galán, Lidice

    2009-11-01

    Learning to read is one of the most important cognitive milestones in the human social environment. One of the most accepted models explaining such process is the Double-Route Cascaded Model. It suggests the existence of two reading strategies: lexical and sublexical. In the Spanish language there are some contradictions about how these strategies are applied for reading. In addition, there are only a few studies dealing with the analysis of shifts between them, achieving a fluent reading process. In this paper we use a reading task including words and pseudowords for characterizing the cost of shifting between reading strategies in children with developmental dyslexia and normal controls. Our results suggest the presence of both strategies in these two experimental groups. In controls, both strategies become more efficient in correspondence to the increased exposition to written material. However, in children with developmental dyslexia only the lexical strategy exhibits such improvement. Their also point to a low cost for shifting between strategies in controls and a much more significant one in children with developmental dyslexia, differentiating subgroups with distinct shifting patterns.

  20. Computer modeling and design of diagnostic workstations and radiology reading rooms

    Science.gov (United States)

    Ratib, Osman M.; Amato, Carlos L.; Balbona, Joseph A.; Boots, Kevin; Valentino, Daniel J.

    2000-05-01

    We used 3D modeling techniques to design and evaluate the ergonomics of diagnostic workstation and radiology reading room in the planning phase of building a new hospital at UCLA. Given serious space limitations, the challenge was to provide more optimal working environment for radiologists in a crowded and busy environment. A particular attention was given to flexibility, lighting condition and noise reduction in rooms shared by multiple users performing diagnostic tasks as well as regular clinical conferences. Re-engineering workspace ergonomics rely on the integration of new technologies, custom designed cabinets, indirect lighting, sound-absorbent partitioning and geometric arrangement of workstations to allow better privacy while optimizing space occupation. Innovations included adjustable flat monitors, integration of videoconferencing and voice recognition, control monitor and retractable keyboard for optimal space utilization. An overhead compartment protecting the monitors from ambient light is also used as accessory lightbox and rear-view projection screen for conferences.

  1. Neuroelectric correlates of a neuropsychological model of word decoding and semantic processing in reading disabled children.

    Science.gov (United States)

    Ostrosky-Solís, F; Canseco, E; Meneses, S; Prospero, O; Zarabozo, D; Ardila, A

    1987-07-01

    significant differences were observed. The results are discussed in accordance with a hypothetical model of the neural bases underlying reading. The model takes into account the complexity of the reading process and the various cognitive skills required for its adequate performance, and emphasizes a complex, dynamic interplay between occipital, parietal and temporal areas.

  2. The role of AVDR in linear cascade testing

    Institute of Scientific and Technical Information of China (English)

    Bo Song; Wing F.Ng

    2007-01-01

    Linear cascade testing plays an important role in the research and development of turbomachinery and is widelv used over the world.The ideal cascade model of a turbomachinery blade row is two-dimensional.In actual linear cascade tesring,the flow through the test section converges due to the development of the boundary layer and secondary flow along the sidewall surfaces of the test section.Axial velocity density ratio(AVDR)is adopted to account for the deviation of the tested cascade flow from the ideal 2D model.Among numerous published cascade works,the influence of AVDR on cascade performance is seen to be complicated with many affecting factors,such as those related to cascade/blade geometry and flow conditions.Also,controlling AVDR is limited by the facility capability.Furthermore'real blade-to-blade flow in turborrlachines is usually associated with AVDR greater than unity due to limited span of blades between the hub and shroud such that cascade testing without reducing AVDR could be favored sometimes.All these facets add complexity and diversification to the matter.The current paper reviews previous studies and results on AVDR.ConsoIidated understanding on the role of AVDR and recommendations on how to deal with it in linear cascade testing are provided.

  3. A new cascadic multigrid

    Institute of Scientific and Technical Information of China (English)

    SHI; Zhongci

    2001-01-01

    [1]Bornemann, F., Deuflhard, P., The cascadic multigrid method for elliptic problems, Numer. Math., 996, 75: 35.[2]Bornemann, F., Deuflhard, P., The cascadic multigrid method, The Eighth International Conference on Domain Decomposition Methods for Partial Differential Equations (eds. Glowinski, R., Periaux, J., Shi, Z. et al.), New York: John Wiley and Sons, 997.[3]Bornemann, F., Krause, R., Classical and cascadic multigrid-methodogical comparison, Proceedings of the 9th International Conference on Domain Decomposition (eds. Bjorstad, P., Espedal, M., Keyes, D.), New York: John Wiley and Sons, 998.[4]Shaidurov, V., Some estimates of the rate of convergence for the cascadic conjugate gradient method, Comp. Math. Applic., 996, 3: 6.[5]Shi, Z., Xu, X., Cascadic multigrid method for the second order elliptic problem, East-West J. Numer. Math., 998, 6: 309.[6]Shi, Z., Xu, X., Cascadic multigrid for elliptic problems, East-West J. Numer. Math., 999, 7: 99.[7]Shi, Z., Xu, X., Cascadic multigrid method for the plate bending problem, East-West J. Numer. Math., 998, 6: 37.[8]Braess, D., Dahmen, W., A cascade multigrid algorithm for the Stokes equations, Number. Math., 999, 82: 79.[9]Shi, Z., Xu, X., Cascadic multigrid for parabolic problems, J. Comput. Math., 2000, 8: 450.[10]Ciarlet, P.,The Finite Element Method for Elliptic Problems, Amsterdam: North-Holland, 978.[11]Zienkiewicz, O. C., The Finite Element Method, 3rd. ed., London: McGraw-Hill, 977.[12]Powell, M. J. D., Sabin, M. A., Piecewise quadratic approximations on triangles, ACM Trans. Mat. Software, 977, 3: 36.[13]Xu, J., The auxiliary space method and optimal multigrid precondition techniques for unstructured grids, Computing, 996, 56: 25.[14]Bank, R., Dupont, T., An optimal order process for solving finite element equations, Math. Comput., 980, 36: 35.[15]Brenner, S., Convergence of nonconforming multigrid methods without full elliptic regularity, Math

  4. Remembering words in context as predicted by an associative read-out model.

    Science.gov (United States)

    Hofmann, Markus J; Kuchinke, Lars; Biemann, Chris; Tamm, Sascha; Jacobs, Arthur M

    2011-01-01

    Interactive activation models (IAMs) simulate orthographic and phonological processes in implicit memory tasks, but they neither account for associative relations between words nor explicit memory performance. To overcome both limitations, we introduce the associative read-out model (AROM), an IAM extended by an associative layer implementing long-term associations between words. According to Hebbian learning, two words were defined as "associated" if they co-occurred significantly often in the sentences of a large corpus. In a study-test task, a greater amount of associated items in the stimulus set increased the "yes" response rates of non-learned and learned words. To model test-phase performance, the associative layer is initialized with greater activation for learned than for non-learned items. Because IAMs scale inhibitory activation changes by the initial activation, learned items gain a greater signal variability than non-learned items, irrespective of the choice of the free parameters. This explains why the slope of the z-transformed receiver-operating characteristics (z-ROCs) is lower one during recognition memory. When fitting the model to the empirical z-ROCs, it likewise predicted which word is recognized with which probability at the item-level. Since many of the strongest associates reflect semantic relations to the presented word (e.g., synonymy), the AROM merges form-based aspects of meaning representation with meaning relations between words.

  5. Insights from analyzing and modelling cascading multi-lake outburst flood events in the Santa Cruz Valley (Cordillera Blanca, Perú)

    Science.gov (United States)

    Emmer, Adam; Mergili, Martin; Juřicová, Anna; Cochachin, Alejo; Huggel, Christian

    2016-04-01

    results are very promising, lessons learned for r.avaflow model are the need for (i) an improved concept to determine the flow boundaries; and (ii) thorough parameter tests. High demands on the resolution and quality of the DEM are revealed. From our event and modelling analysis we conclude the following: mass movements in the headwaters of hydrologically connected lake and river systems may affect the catchment in complex and cascading ways. Flood and mass flow magnitudes can be both intensified or attenuated along the pathway. Geomorphological analysis and related modelling efforts may elucidate the related hazards as a basis to reduce the associated risks to downstream communities and infrastructures. Keywords: cascading processes, dam failure, glacial lake outburst flood (GLOF), high-mountain lakes, r.avaflow

  6. An Explanation of Reading Comprehension across Development Using Models from Cattell-Horn-Carroll Theory: Support for Integrative Models of Reading

    Science.gov (United States)

    Floyd, Randy; Meisinger, Elizabeth; Gregg, Noel; Keith, Timothy

    2012-01-01

    The purpose of this research was to investigate the cognitive abilities that explain reading comprehension across childhood and early adulthood. Drawing from the standardization sample of the Woodcock-Johnson III, analyses were conducted with large samples at age levels spanning early childhood to early adulthood: 5 to 6 (n = 639), 7 to 8 (n =…

  7. Magma reservoirs from the upper crust to the Moho inferred from high-resolution Vp and Vs models beneath Mount St. Helens, Cascades, USA

    Science.gov (United States)

    Kiser, Eric; Levander, Alan; Zelt, Colin; Palomeras, Imma; Schmandt, Brandon; Hansen, Steven; Creager, Kenneth; Ulberg, Carl

    2016-04-01

    Mount St. Helens is currently the most active volcano along the Cascadia arc. Though several studies investigated the magmatic system beneath Mount St. Helens following the May 18, 1980 eruption, tomographic imaging of the system has been limited to ~10 km depth due to the distribution of earthquakes in the region. This has made it difficult to estimate the volume of the shallow magma reservoir beneath the volcano, the regions of magma entry into the lower crust, and the connectivity of this magma system throughout the crust. The latter is particularly interesting as one interpretation of the Southern Washington Cascades Conductor (SWCC) suggests that the Mount St Helens and Mount Adams volcanic systems are connected in the middle crust (Hill et al., 2009). The multi-disciplinary iMUSH (imaging Magma Under St. Helens) project is designed to investigate these and other fundamental questions associated with Mount St. Helens. Here we present the first high-resolution 2D Vp and Vs models derived from travel-time data from the iMUSH 3D active-source seismic experiment. The experiment consisted of ~6000 seismograph stations which recorded 23 explosions and hundreds of local earthquakes. Directly beneath Mount St. Helens, we observe a high Vp/Vs body, inferred to be the upper/middle crustal magma reservoir, between 4 and 13 km depth. We observe a second high Vp/Vs body, likely of magmatic origin, at roughly the same depth beneath Indian Heaven Volcanic Field, which last erupted 9 ka. Southeast of Mount St. Helens is a low Vp column extending from the middle crust, ~15 km depth, to the Moho at ~40 km depth. A cluster of deep long-period events, typically associated with injection of magma, occurs at the northwestern boundary of this low Vp column. We interpret this as the middle-lower crust magma reservoir. In the lower crust, high Vp features bound the magma reservoir directly beneath Mount St. Helens and the Indian Heaven Volcanic Field. One explanation for these high Vp

  8. Reading Logs and Literature Teaching Models in English Language Teacher Education

    OpenAIRE

    2015-01-01

    Reading logs are regularly used in foreign language education since they are not only critical in the development of reading comprehension but may also be instrumental in taking readers beyond the referential into the representational realms of language. In this paper we offer the results of a qualitative analysis of a series of reading logs written by advanced students for a literature course in an English language teacher education program in Argentina. The logs were coded according to the ...

  9. Multi-Timescale Cascading Outage Model Considering Generator Excitation Protection and OLTC%考虑发电机励磁保护和OLTC的多时间尺度连锁故障模型

    Institute of Scientific and Technical Information of China (English)

    姚锐; 黄少伟; 刘锋

    2015-01-01

    Voltage and reactive power characteristics play an important role in cascading outages and blackouts in power systems. In this paper, a multi-timescale cascading outage model considering on-load tap changer (OLTC) and generator excitation protection was proposed. This model proposed a multi-timescale cascading outage simulation framework, in which clear expression of time in cascading outage simulation was realized, thus overcame limitation of traditional models. Modeling of generator excitation protection and OLTC simulation were introduced in this model. The IEEE-30 system case studies analyzed mechanisms of generator excitation protection and OLTC, and their influence on cascading outage risk and process. Moreover, phrasal characteristics of cascading outages are analyzed using this model.%世界范围内多次连锁故障和大停电事故表明,无功电压相关因素对连锁故障具有重要影响。提出了一种计及有载调压变压器(on-load tap changer,OLTC)和发电机励磁保护的多时间尺度大停电模型。该模型提出了对无功电压具有重要影响的发电机励磁保护和OLTC动作的建模方法,并进一步基于该模型提出了多时间尺度连锁故障模拟方法,实现了连锁故障动态过程的清晰描述,克服了传统连锁故障模型在此方面的局限性。文中用IEEE 30节点系统进行了连锁故障仿真计算,分析了发电机励磁保护、OLTC动作等与无功电压密切相关的因素对连锁故障的影响及机理,并揭示了连锁故障的若干阶段性特征。

  10. Comparative transcriptome analysis of isogenic cell line models and primary cancers links capicua (CIC) loss to activation of the MAPK signalling cascade.

    Science.gov (United States)

    LeBlanc, Veronique G; Firme, Marlo; Song, Jungeun; Chan, Susanna Y; Lee, Min Hye; Yip, Stephen; Chittaranjan, Suganthi; Marra, Marco A

    2017-06-01

    CIC encodes a transcriptional repressor, capicua (CIC), whose disrupted activity appears to be involved in several cancer types, including type I low-grade gliomas (LGGs) and stomach adenocarcinomas (STADs). To explore human CIC's transcriptional network in an isogenic background, we developed novel isogenic CIC knockout cell lines as model systems, and used these in transcriptome analyses to study the consequences of CIC loss. We also compared our results with analyses of transcriptome data from TCGA for type I LGGs and STADs. We identified 39 candidate targets of CIC transcriptional regulation, and confirmed seven of these as direct targets. We showed that, although many CIC targets appear to be context-specific, the effects of CIC loss converge on the dysregulation of similar biological processes in different cancer types. For example, we found that CIC deficiency was associated with disruptions in the expression of genes involved in cell-cell adhesion, and in the development of several cell and tissue types. We also showed that loss of CIC leads to overexpression of downstream members of the mitogen-activated protein kinase (MAPK) signalling cascade, indicating that CIC deficiency may present a novel mechanism for activation of this oncogenic pathway. © 2017 The Authors. Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland. © 2017 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

  11. Scaling of particle production with number of participants in high-energy A + A collisions in the parton-cascade model

    CERN Document Server

    Srivastava, D K; Srivastava, Dinesh Kumar; Geiger, Klaus

    1999-01-01

    In view of the recent WA98 data of $\\pi^0$ spectra from central Pb+Pb collisions at the CERN SPS, we analyze the production of neutral pions for A+A collisions across the periodic table at $\\sqrt{s}=17$ AGeV and 200 AGeV within the framework of the parton-cascade model for relativistic heavy ion collisions. The multiplicity of the pions (having $p_T > 0.5$ GeV) in the central rapidity region, is seen to scale as $\\sim (N_{part})^{\\alpha}$, where $N_{part}$ is the number of participating nucleons, which we have approximated as 2A for central collisions of identical nuclei. We argue that the deviation of $\\alpha$ ($\\simeq 1.2$) from unity may have its origin in the multiple scattering suffered by the partons. We also find that the constant of proportionality in the above scaling relation increases substantially in going from SPS to RHIC energies. This would imply that the (semi)hard partonic activity becomes a much cleaner signal above the soft particle production at the higher energy of RHIC, and thus much les...

  12. Scaling of particle production with number of participants in high-energy A + A collisions in the parton-cascade model

    CERN Document Server

    Srivastava, D K; Srivastava, Dinesh K.; Geiger, Klaus

    1998-01-01

    In view of the recent WA98 data of pi0 spectra from central Pb+Pb collisions at the CERN SPS, we analyze the production of neutral pions for A+$ collisions across the periodic table at sqrt(s)=17 AGeV and 200 AGeV within the framework of the parton-cascade model for relativistic heavy ion collisions. The multiplicity of the pions (having pT > 0.5 GeV/c) in the central rapidity region, is seen to scale as \\sim (N_part)^alpha, where N_part$ is the number of participating nucleons, which we have approximated as 2A for central collisions of identical nuclei. We argue that the deviation of \\alpha (\\simeq 1.2) from unity may have its origin in the multiple scattering suffered by the partons. We also find that the constant of proportionality in the above scaling relation increases substantially in going from SPS to RHIC energies. This would imply that the (semi)hard partonic activity becomes a much cleaner signal above the soft particle production at the higher energy of RHIC, and thus much less dependent on the (la...

  13. Scaling of particle production with number of participants in high-energy A+A collisions in the parton-cascade model

    CERN Document Server

    Srivastava, D K

    1999-01-01

    In view of the recent WA98 data of pi /sup 0/ spectra from central Pb +Pb collisions at the CERN SPS, we analyze the production of neutral pions for A+A collisions across the periodic table at square root (s) =17 AGeV and 200 AGeV within the framework of the parton-cascade model for relativistic heavy ion collisions. The multiplicity of the pions (having p/sub T/ > 0.5 GeV) in the central rapidity region, is seen to scale as ~(N/sub part/)/sup alpha /, where N/sub part/ is the number of participating nucleons, which we have approximated as 2 A for central collisions of identical nuclei. We argue that the deviation of alpha ( equivalent to 1.2) from unity may have its origin in the multiple scattering suffered by the partons. We also find that the constant of proportionality in the above scaling relation increases substantially in going from SPS to RHIC energies. This would imply that the (semi)hard partonic activity becomes a much cleaner signal above the soft particle production at the higher energy of RHIC,...

  14. Reading faster

    OpenAIRE

    Paul Nation

    2009-01-01

    This article describes the visual nature of the reading process as it relates to reading speed. It points out that there is a physical limit on normal reading speed and beyond this limit the reading process will be different from normal reading where almost every word is attended to. The article describes a range of activities for developing reading fluency, and suggests how the development of fluency can become part of a reading programme.

  15. Reading faster

    Directory of Open Access Journals (Sweden)

    Paul Nation

    2009-12-01

    Full Text Available This article describes the visual nature of the reading process as it relates to reading speed. It points out that there is a physical limit on normal reading speed and beyond this limit the reading process will be different from normal reading where almost every word is attended to. The article describes a range of activities for developing reading fluency, and suggests how the development of fluency can become part of a reading programme.

  16. Harmonic cascade FEL designs for LUX

    Energy Technology Data Exchange (ETDEWEB)

    Penn, G.; Reinsch, M.; Wurtele, J.; Corlett, J.N.; Fawley, W.M.; Zholents, A.; Wan, W.

    2004-07-16

    LUX is a design concept for an ultrafast X-ray science facility, based on an electron beam accelerated to GeV energies in are circulating linac. Included in the design are short duration (200 fs or shorter FWHM) light sources using multiple stages of higher harmonic generation, seeded by a 200-250 nm laser of similar duration. This laser modulates the energy of a group of electrons within the electron bunch; this section of the electron bunch then produces radiation at a higher harmonic after entering a second, differently tuned undulator. Repeated stages in a cascade yield increasing photon energies up to 1 keV. Most of the undulators in the cascade operate in the low-gain FEL regime. Harmonic cascades have been designed for each pass of the recirculating linac up to a final electron beam energy of 3.1 GeV. For a given cascade, the photon energy can be selected over a wide range by varying the seed laser frequency and the field strength in the undulators. We present simulation results using the codes GENESIS and GINGER, as well as the results of analytical models which predict FEL performance. We discuss lattice considerations pertinent for harmonic cascade FELs, as well as sensitivity studies and requirements on the electron beam.

  17. Period doubling cascades of prey-predator model with nonlinear harvesting and control of over exploitation through taxation

    Science.gov (United States)

    Gupta, R. P.; Banerjee, Malay; Chandra, Peeyush

    2014-07-01

    The present study investigates a prey predator type model for conservation of ecological resources through taxation with nonlinear harvesting. The model uses the harvesting function as proposed by Agnew (1979) [1] which accounts for the handling time of the catch and also the competition between standard vessels being utilized for harvesting of resources. In this paper we consider a three dimensional dynamic effort prey-predator model with Holling type-II functional response. The conditions for uniform persistence of the model have been derived. The existence and stability of bifurcating periodic solution through Hopf bifurcation have been examined for a particular set of parameter value. Using numerical examples it is shown that the system admits periodic, quasi-periodic and chaotic solutions. It is observed that the system exhibits periodic doubling route to chaos with respect to tax. Many forms of complexities such as chaotic bands (including periodic windows, period-doubling bifurcations, period-halving bifurcations and attractor crisis) and chaotic attractors have been observed. Sensitivity analysis is carried out and it is observed that the solutions are highly dependent to the initial conditions. Pontryagin's Maximum Principle has been used to obtain optimal tax policy to maximize the monetary social benefit as well as conservation of the ecosystem.

  18. Simulation of Alfv n frequency cascade modes in reversed shear discharges using a Landau-closure model

    Energy Technology Data Exchange (ETDEWEB)

    Spong, Donald A [ORNL

    2013-01-01

    The dynamics of energetic particle destabilized Alfve n frequency sweeping modes in tokamak reversed-shear safety factor discharges are modelled using a new Landau-closure model that includes coupling to geodesic acoustic wave dynamics and closure relations optimized for energetic particle Alfve n mode resonances. Profiles and equilibria are based upon reconstructions of a DIII-D discharge (#142111) in which a long sequence of frequency sweeping modes were observed. This model (TAEFL) has recently been included in a verification and validation study of n = 3 frequency sweeping modes for this case along with two gyrokinetic codes, GTC and GYRO. This paper provides a more detailed documentation of the equations and methods used in the TAEFL model and extends the earlier calculation to a range of toroidal mode numbers: n = 2 to 6. By considering a range of toroidal mode numbers and scanning over a range of safety factor profiles with varying qmin, both up-sweeping frequency (reversed-shear Alfve n eigenmode) and down-sweeping frequency (toriodal Alfve n eigenmode) modes are present in the results and show qualitative similarity with the frequency variations observed in the experimental spectrograms.

  19. Classifying Chinese children with dyslexia by dual-route and triangle models of Chinese reading.

    Science.gov (United States)

    Wang, Li-Chih; Yang, Hsien-Ming

    2014-11-01

    This present study focuses on classifying developmental dyslexia by combining two famous models, the dual-route model and the triangle model of Chinese reading, re-examining validity of the subtypes, and observing the error types of word recognition for each subtype. Sixty-sixth graders with dyslexia in Chinese and 45 sixth graders who were matched by age and IQ with the dyslexic group were involved in the present study. Twelve (20%) sixth graders from the dyslexic group were classified as having phonological dyslexia, 11 (18.3%) were classified as surface dyslexia, 12 (20%) were classified as deep dyslexia, and five (8.3%) of them were classified as displaying more than one kind of deficit. Besides, still more than half (31; 51.7%) of the dyslexic group did not belong to any subtypes here. These subtypes had a good validity based on comparison of their phonological awareness, orthography, and semantics. Finally, for their error types of word recognition, both children with multiple-deficit dyslexia and children with non-subtype dyslexia showed a proportional pattern of six kinds of errors. Children with phonological dyslexia showed more phonetic errors and analogy errors, children with surface dyslexia showed more visual errors and analogy errors, and children with deep dyslexia showed more semantic errors and selective errors.

  20. Noise propagation in two-step series MAPK cascade.

    Directory of Open Access Journals (Sweden)

    Venkata Dhananjaneyulu

    Full Text Available Series MAPK enzymatic cascades, ubiquitously found in signaling networks, act as signal amplifiers and play a key role in processing information during signal transduction in cells. In activated cascades, cell-to-cell variability or noise is bound to occur and thereby strongly affects the cellular response. Commonly used linearization method (LM applied to Langevin type stochastic model of the MAPK cascade fails to accurately predict intrinsic noise propagation in the cascade. We prove this by using extensive stochastic simulations for various ranges of biochemical parameters. This failure is due to the fact that the LM ignores the nonlinear effects on the noise. However, LM provides a good estimate of the extrinsic noise propagation. We show that the correct estimate of intrinsic noise propagation in signaling networks that contain at least one enzymatic step can be obtained only through stochastic simulations. Noise propagation in the cascade depends on the underlying biochemical parameters which are often unavailable. Based on a combination of global sensitivity analysis (GSA and stochastic simulations, we developed a systematic methodology to characterize noise propagation in the cascade. GSA predicts that noise propagation in MAPK cascade is sensitive to the total number of upstream enzyme molecules and the total number of molecules of the two substrates involved in the cascade. We argue that the general systematic approach proposed and demonstrated on MAPK cascade must accompany noise propagation studies in biological networks.

  1. The Relationship of Print Reading in Tier I Instruction and Reading Achievement for Kindergarten Students at Risk of Reading Difficulties

    Science.gov (United States)

    Wanzek, Jeanne; Roberts, Greg; Al Otaiba, Stephanie; Kent, Shawn C.

    2014-01-01

    For many students at risk of reading difficulties, effective, early reading instruction can improve reading outcomes and set them on a positive reading trajectory. Thus, response-to-intervention models include a focus on a student's Tier I reading instruction as one element for preventing reading difficulties and identifying students with a…

  2. Cascade of chromosomal rearrangements caused by a heterogeneous T-DNA integration supports the double-strand break repair model for T-DNA integration.

    Science.gov (United States)

    Hu, Yufei; Chen, Zhiyu; Zhuang, Chuxiong; Huang, Jilei

    2017-02-28

    Transferred DNA (T-DNA) from Agrobacterium tumefaciens can be integrated into the plant genome. The double-strand break repair (DSBR) pathway is a major model for T-DNA integration. From this model, we expect that two ends of a T-DNA molecule would invade into a single DNA double-strand break (DSB) or independent DSBs in the plant genome. We call the later phenomenon a heterogeneous T-DNA integration which has never been observed. In this work, we demonstrated it in an Arabidopsis T-DNA insertion mutant seb19. To resolve the chromosomal structural changes caused by T-DNA integration at both the nucleotide and chromosome levels, we performed inverse PCR, genome resequencing, fluorescence in situ hybridization and linkage analysis. We found, in seb19, a single T-DNA connected two different chromosomal loci and caused complex chromosomal rearrangements. The specific break-junction pattern in seb19 is consistent with the result of heterogeneous T-DNA integration but not of recombination between two T-DNA insertions. We demonstrated that, in seb19, heterogeneous T-DNA integration evoked a cascade of incorrect repair of seven DSBs on chromosome 4 and 5, and then produced translocation, inversion, duplication and deletion. Heterogeneous T-DNA integration supports the DSBR model and suggests that two ends of a T-DNA molecule could be integrated into the plant genome independently. Our results also show a new origin of chromosomal abnormalities. This article is protected by copyright. All rights reserved.

  3. Design of model for analytic method of Android malware based on cascade defense network%Android平台下级联防御网模型的设计

    Institute of Scientific and Technical Information of China (English)

    张悦; 郑东; 张应辉

    2016-01-01

    为充分利用每个手机的通讯资源,结合恶意软件传播的特点,构思一种级联防御网模型。在现有 Android 恶意代码检测方式的基础上,将检测的结果通过网络由下向上进行汇总,各级节点在分析之后,根据分析的结果做出相应的抉择,防止病毒的进一步扩散。模拟传播感染实验结果表明,该模型具有良好的防范效果,在其作用下,感染率减少了39.3%,查杀耗时平均减少了379 ms。%To make full use of the communication resources of each cell phone,combining with the spread features of malicious applications,a malicious code detection model called cascade defense network was designed.Based on the existing Android mal-ware detection method,after analyzing the nodes at different levels,the detection results were collected through the network. According to the analysis,the nodes made appropriate choice,which prevented the virus spreading further.Infection experimen-tal results show the model is highly effective.Under the action of the model,the infection rate is reduced by 3 9.3%,and the average killing time is decreased by 3 7 9 ms.

  4. Energy cascade in internal wave attractors

    CERN Document Server

    Brouzet, Christophe; Joubaud, Sylvain; Sibgatullin, Ilias; Dauxois, Thierry

    2016-01-01

    One of the pivotal questions in the dynamics of the oceans is related to the cascade of mechanical energy in the abyss and its contribution to mixing. Here, we propose internal wave attractors in the large amplitude regime as a unique self-consistent experimental and numerical setup that models a cascade of triadic interactions transferring energy from large-scale monochro-matic input to multi-scale internal wave motion. We also provide signatures of a discrete wave turbulence framework for internal waves. Finally, we show how beyond this regime, we have a clear transition to a regime of small-scale high-vorticity events which induce mixing. Introduction.

  5. MAP kinase cascades in Arabidopsis innate immunity

    DEFF Research Database (Denmark)

    Rasmussen, Magnus Wohlfahrt; Roux, Milena Edna; Petersen, Morten

    2012-01-01

    immune responses. In the model Arabidopsis, molecular genetic evidence implicates a number of MAPK cascade components in PAMP signaling, and in responses to immunity-related phytohormones such as ethylene, jasmonate, and salicylate. In a few cases, cascade components have been directly linked...... to the transcription of target genes or to the regulation of phytohormone synthesis. Thus MAPKs are obvious targets for bacterial effector proteins and are likely guardees of resistance proteins, which mediate defense signaling in response to the action of effectors, or effector-triggered immunity. This mini...

  6. MAP Kinase Cascades in Plant Innate Immunity

    Directory of Open Access Journals (Sweden)

    Magnus Wohlfahrt Rasmussen

    2012-07-01

    Full Text Available Plant mitogen-activated protein kinase (MAPK cascades generally transduce extracellular stimuli into cellular responses. These stimuli include the perception of pathogen-associated molecular patterns (PAMPs by host transmembrane pattern recognition receptors (PRRs which trigger MAPK-dependent innate immune responses. In the model Arabidopsis, molecular genetic evidence implicates a number of MAPK cascade components in PAMP signaling, and in responses to immunity-related phytohormones such as ethylene, jasmonate and salicylate. In a few cases, cascade components have been directly linked to the transcription of target genes or to the regulation of phytohormone synthesis. Thus MAPKs are obvious targets for bacterial effector proteins and are likely guardees of resistance (R proteins, which mediate defense signaling in response to the action of effectors, or effector-triggered immunity (ETI. This mini-review discusses recent progress in this field with a focus on the Arabidopsis MAPKs MPK3, 4, 6 and 11 in their apparent pathways.

  7. Relations Among Oral Reading Fluency, Silent Reading Fluency, and Reading Comprehension: A Latent Variable Study of First-Grade Readers

    OpenAIRE

    Y. S. Kim; Wagner, Richard K.; Foster, E.

    2011-01-01

    The present study examined oral and silent reading fluency and their relations with reading comprehension. In a series of structural equation models (SEM) with latent variables using data from 316 first-grade students, (1) silent and oral reading fluency were found to be related yet distinct forms of reading fluency; (2) silent reading fluency predicted reading comprehension better for skilled readers than for average readers; (3) list reading fluency predicted reading compr...

  8. Portuguese School Libraries Evaluation Model: An Analysis of Primary Schools' Results for the "Reading and Literacy" Domain

    Science.gov (United States)

    Martins, Jorge Tiago; Martins, Rosa Maria

    2012-01-01

    This paper reports the implementation results of the Portuguese School Libraries Evaluation Model, more specifically the results of primary schools self-evaluation of their libraries' reading promotion and information literacy development activities. School libraries that rated their performance as either "Excellent" or "Poor"…

  9. Portuguese School Libraries Evaluation Model: An Analysis of Primary Schools' Results for the "Reading and Literacy" Domain

    Science.gov (United States)

    Martins, Jorge Tiago; Martins, Rosa Maria

    2012-01-01

    This paper reports the implementation results of the Portuguese School Libraries Evaluation Model, more specifically the results of primary schools self-evaluation of their libraries' reading promotion and information literacy development activities. School libraries that rated their performance as either "Excellent" or "Poor"…

  10. Portuguese School Libraries Evaluation Model: An Analysis of Primary Schools' Results for the "Reading and Literacy" Domain

    Science.gov (United States)

    Martins, Jorge Tiago; Martins, Rosa Maria

    2012-01-01

    This paper reports the implementation results of the Portuguese School Libraries Evaluation Model, more specifically the results of primary schools self-evaluation of their libraries' reading promotion and information literacy development activities. School libraries that rated their performance as either "Excellent" or "Poor" have been…

  11. Preliminary Notes on a Strategy-oriented Teaching Model of EFL Reading

    Institute of Scientific and Technical Information of China (English)

    JingSurong

    2004-01-01

    This paper first reviews the status quo of EFL reading teaching in FLC (the Foreign Languages College of Shanxi University) with some problems detected. The most distinct one is that most reading teachers lack systematic theoretical knowledge to guide their teaching practice, which has led to unsatisfactory teaching effects in terms of lesson planning,

  12. Modeling Child-Based Theoretical Reading Constructs with Struggling Adult Readers

    Science.gov (United States)

    Nanda, Alice O.; Greenberg, Daphne; Morris, Robin

    2010-01-01

    This study examined whether measurement constructs behind reading-related tests for struggling adult readers are similar to what is known about measurement constructs for children. The sample included 371 adults reading between the third-and fifth-grade levels, including 127 men and 153 English speakers of other languages. Using measures of skills…

  13. Modeling Child-Based Theoretical Reading Constructs with Struggling Adult Readers

    Science.gov (United States)

    Nanda, Alice O.; Greenberg, Daphne; Morris, Robin

    2010-01-01

    This study examined whether measurement constructs behind reading-related tests for struggling adult readers are similar to what is known about measurement constructs for children. The sample included 371 adults reading between the third-and fifth-grade levels, including 127 men and 153 English speakers of other languages. Using measures of skills…

  14. Understanding Racism and Sexism in Harry Potter and Stuart Hall’s Model of Three Reading Positions

    Directory of Open Access Journals (Sweden)

    Brigita Pavšič

    2007-06-01

    Full Text Available In the Harry Potter book series there are several examples of sexist and racist stereotypes which can distort children’s understanding of reality and thus cause them to adopt prejudices and inappropriate judgments. The reason for such strong impact on the young readers can be explained with the use of Stuart Hall’s encoding/decoding model that suggests three reading positions and; as a result; three different ways of understanding one and the same text. The fact that oppositional reading; which allows the reader to asses the text critically; can only be adopted by educated and well-read readers explains why adult help is needed in directing the child reader towards a correct interpretation of such deficiencies of a text and offering a grounded explanation.

  15. Spatial Cascaded Model for Personalized Recommender System%空间级联模式下的个性推荐模拟

    Institute of Scientific and Technical Information of China (English)

    李奥勇; 许珺

    2016-01-01

    Recommendation system has become mature and been successfully applied in many fields since its emergence. Due to the popularization of different types of mobile terminals, spatial information is brought into the recommendation systems. However, the existing researches mainly focus on spatial locations and rarely consider spatial relations. Meanwhile, the existing recommendation algorithms usually consider only the user’s history behaviors but not the influence of future behaviors on current recommendations. According to the activity chain theory, future activities have an impact on the current behavior as well as the past activities did. If a user has two steps of information retrieval, and the second step is based on the result of the first step, he would choose an item from the result which is convenient for him to make the second choice, and thus he can get the best choices at both steps of retrieval. That is to say, the current selection would be affected by the next retrieval of information. In this paper, we model the spatial distribution of the travel targets by considering one’s future intentions as well as the past data, and propose a spatial cascaded model for personalized recommender system. The model is built for situations with a series of continuous choices in the spatial space based on the traditional recommendation algorithm and the influence of future activities. The influence of spatial relation is introduced into the traditional recommendation algorithm as a distance decay function. In order to prove the feasibility of spatial cascaded recommender system, a restaurant recommender system is developed based on the proposed model. Taking into account of user’s preference and distance, a cost-benefit index was proposed to evaluate the result. The result shows that when considering further activities and spatial relations in recommendation, the system can produce a more reasonable result.%自个性化推荐系统出现以来,逐渐成熟并

  16. Models and Design Judgment: Conflicting Perspectives on Redesigning a Doctoral Readings Course

    Directory of Open Access Journals (Sweden)

    Colin M. Gray

    2012-01-01

    Full Text Available The purpose of this project was to document the redesign of an existing doctoral reading course for an online environment. Potential methods for actualizing the proposed course structure in an online environment, including technology tools and interactions are discussed. The design process began within the framework of the Four-Component Instructional Design (4C/ID model (van Merriënboer, 1997; van Merriënboer & Kirchner, 2007, which advocates a shift from topic-centeredness to a task-centered course organization, but quickly evolved into a flexible, iterative design process that was informed by prototyping, the judgment of the design team, and various theories of knowledge and knowing. The 4C/ID model represented our philosophical starting point, but our focus quickly shifted to a more flexible, eclectic process as we attempted to reconcile conflicting constraints on the final design. Along with the redevelopment of course objectives to meet strategic goals within the doctoral program came a focus on facilitating research thinking of the students rather than teaching isolated research tasks. The design process resulted in changes to the current residential course, which then provided an opportunity for further investigation.

  17. HEIST: An event-scale model of cascading water and solute fronts through the vadose zone (Invited)

    Science.gov (United States)

    Harman, C. J.; Basu, N. B.; Rao, P. C.; Sivapalan, M.

    2009-12-01

    The transport of a sorbing, degrading solute (such as Atrazine) through the soil is largely driven by infiltrating water from storms or irrigation, and so depends on the interactions between the timing and characteristics of the rainfall or irrigation events, the properties of the solute, soil characteristics (e.g, porosity, macropore density etc.), and the antecedent soil moisture conditions. This interaction causes the time series inputs of the solute to be “filtered” prior to reaching the watertable, so that the timing, frequency and magnitude of output events is altered. While many previous studies have examined the movement of solutes through soils for a particular site, few have examined the nature of this filtering in more general terms. In this work we present an elegant 1-D model of solute transport through the soil, driven by infiltration events, that is designed to examine this filtering effect. A unique feature of this model is the event-scale time-stepping. By assuming that infiltration and redistribution processes occur instantaneously during an event, while degradation, mobilization, and evapotranspiration are the only important processes occurring between storms, analytical expressions can be derived for the event-to-event transformations of the input signal within the system. Solutes can be surface applied in recalcitrant and labile forms, with first-order mass transfer between the pools, and linear reversible sorption. Infiltrating water mobilizes the labile dissolved solute, generating a point load that moves through the soil with wetting fronts generated by storm events. The retardation and first-order decay of the point-loads eventually decouples them from the wetting fronts they first entered with, allowing solutes to concentrate in the profile. Because only one timestep is required per storm, the model runs very fast, allowing us to examine the effect of different parameter combinations on the filtering. The results show that

  18. Cascading Node Failure with Continuous States in Random Geometric Networks

    CERN Document Server

    Kamran, Khashayar

    2016-01-01

    The increasing complexity and interdependency of today's networks highlight the importance of studying network robustness to failure and attacks. Many large-scale networks are prone to cascading effects where a limited number of initial failures (due to attacks, natural hazards or resource depletion) propagate through a dependent mechanism, ultimately leading to a global failure scenario where a substantial fraction of the network loses its functionality. These cascading failure scenarios often take place in networks which are embedded in space and constrained by geometry. Building on previous results on cascading failure in random geometric networks, we introduce and analyze a continuous cascading failure model where a node has an initial continuously-valued state, and fails if the aggregate state of its neighbors fall below a threshold. Within this model, we derive analytical conditions for the occurrence and non-occurrence of cascading node failure, respectively.

  19. Interrelation of structure and operational states in cascading failure of overloading lines in power grids

    Science.gov (United States)

    Xue, Fei; Bompard, Ettore; Huang, Tao; Jiang, Lin; Lu, Shaofeng; Zhu, Huaiying

    2017-09-01

    As the modern power system is expected to develop to a more intelligent and efficient version, i.e. the smart grid, or to be the central backbone of energy internet for free energy interactions, security concerns related to cascading failures have been raised with consideration of catastrophic results. The researches of topological analysis based on complex networks have made great contributions in revealing structural vulnerabilities of power grids including cascading failure analysis. However, existing literature with inappropriate assumptions in modeling still cannot distinguish the effects between the structure and operational state to give meaningful guidance for system operation. This paper is to reveal the interrelation between network structure and operational states in cascading failure and give quantitative evaluation by integrating both perspectives. For structure analysis, cascading paths will be identified by extended betweenness and quantitatively described by cascading drop and cascading gradient. Furthermore, the operational state for cascading paths will be described by loading level. Then, the risk of cascading failure along a specific cascading path can be quantitatively evaluated considering these two factors. The maximum cascading gradient of all possible cascading paths can be used as an overall metric to evaluate the entire power grid for its features related to cascading failure. The proposed method is tested and verified on IEEE30-bus system and IEEE118-bus system, simulation evidences presented in this paper suggests that the proposed model can identify the structural causes for cascading failure and is promising to give meaningful guidance for the protection of system operation in the future.

  20. Biochemical and pharmacological effects of dipyrone and its metabolites in model systems related to arachidonic acid cascade.

    Science.gov (United States)

    Weithmann, K U; Alpermann, H G

    1985-01-01

    The metabolites of dipyrone (metamizol, Novalgin) were compared with appropriate standard drugs for their influences on the pathways of the arachidonic acid metabolism. The drugs in this study had no significant effects on the lipoxygenase pathway in human neutrophils in vitro. The dipyrone metabolites 4-methylaminoantipyrine (MAAP) and 4-aminoantipyrine (AAP) inhibited prostaglandin synthesis in the 10(-3) to 10(-4) mol/l range thus being comparable to acetylsalicylic acid (ASA), whereas the two additional metabolites 4-acetylaminoantipyrine (AAAP) and 4-formylaminoantipyrine (FAAP) were practically inactive. This result is in accordance with the effects of the metabolites on the formation of oedema in the arthritis rat model, and supports published data showing that MAAP and AAP are the metabolites responsible for the clinical effects of dipyrone. Further systems in our study depending at least partially on the prostaglandin pathway were the release of antiaggregatory activity from rat aortae in vitro and the aggregation of human platelets induced by arachidonic acid in vitro. MAAP exhibits antiaggregatory activity (IC50 5 x 10(-6) mol/l), whereas the inhibitory effect on the vascular antiaggregatory release is much weaker. Compared to normals platelet aggregability ex vivo is enhanced in arthritic rats, but could significantly be lowered again by treatment of the rats with MAAP. A further system studied was the release of 6-keto-PGF1 alpha from rat mucosa in vitro and ex vivo. In vitro there is inhibition to be found with MAAP as well as with ASA. Ex vivo, however, dipyrone or MAAP slightly stimulates mucosal 6-keto-PGF1 alpha rather than inhibiting it, whereas ASA exerts inhibition, as expected.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. TOPOLOGY AND VORTEX STRUCTURES OF A CURVING TURBINE CASCADE WITH TIP CLEARANCE ( Ⅰ )- EXPERIMENTAL MODEL AND TOPOLOGICAL FLOW PATTERNS ON BOTH ENDWALLS AND BLADE SURFACES

    Institute of Scientific and Technical Information of China (English)

    杨庆海; 黄洪雁; 韩万今

    2002-01-01

    By means of ink trace visualization of the flows in conventional straight, positively curved and negatively curved cascades with tip clearance, and measurement of the aerodynamic parameters in the transverse section, and by appling topology theory, the structures on both endwalls and blade surfaces were analyzed. Compared with conventional straight cascade, blade positive curving eliminates the separation line of the upper passage vortex and leads the secondary vortex to change from close separation to open separation,while blade negative curving effects merely the positions of singular points and the intensities and scales of vortex.

  2. Period-doubling cascades galore

    OpenAIRE

    Sander, Evelyn; Yorke, James A.

    2009-01-01

    The appearance of numerous period-doubling cascades is among the most prominent features of {\\bf parametrized maps}, that is, smooth one-parameter families of maps $F:R \\times {\\mathfrak M} \\to {\\mathfrak M}$, where ${\\mathfrak M}$ is a smooth locally compact manifold without boundary, typically $R^N$. Each cascade has infinitely many period-doubling bifurcations, and it is typical to observe -- such as in all the examples we investigate here -- that whenever there are any cascades, there are...

  3. Single phase cascaded H5 inverter with leakage current elimination for transformerless photovoltaic system

    DEFF Research Database (Denmark)

    Guo, Xiaoqiang; Jia, X.; Lu, Z.;

    2016-01-01

    Leakage current reduction is one of the important issues for the transformelress PV systems. In this paper, the transformerless single-phase cascaded H-bridge PV inverter is investigated. The common mode model for the cascaded H4 inverter is analyzed. And the reason why the conventional cascade H...

  4. Computer-aided design and modeling of workstations and radiology reading rooms for the new millennium.

    Science.gov (United States)

    Ratib, O; Valentino, D J; McCoy, M J; Balbona, J A; Amato, C L; Boots, K

    2000-01-01

    Three-dimensional (3D) computer modeling, simulation, and rendering techniques were used to redesign the diagnostic workstations and radiology reading rooms for a proposed hospital with particular attention given to lighting conditions, noise reduction, and optimal use of limited workspace. The results were presented to a panel of multidisciplinary experts and iteratively improved and redesigned with the development or addition of new design criteria or requirements. These 3D techniques allowed faster, more efficient design and presentation of multiple options than is possible with traditional two-dimensional drawings, thereby expediting decision making and resulting in significant savings. The current workstation designs can easily be developed and implemented with available technology at a reasonable cost. They can also accommodate anticipated advances in computer and display technology as well as new imaging paradigms (eg, changes in keyboard and control ergonomics such as adjustable virtual keys on touch-sensitive screens, digital drawing tablets for annotations and controls, direct film digitizing, personal identification devices, offline media readers such as compact disks and digital videodisks, and speech recognition and voice activation). Use of 3D techniques in designing other parts of the radiology department (eg, examination rooms, technologists' areas, physicians' offices) could greatly improve and facilitate the design and implementation of complex settings in these work areas.

  5. Research on Shielded Keywords Based on Cascaded Hidden Markov Model%基于层叠隐马模型的屏蔽关键词研究

    Institute of Scientific and Technical Information of China (English)

    陶非凡

    2014-01-01

    The information age brings a huge improvement in people's lives,but also accompanied by a series of problems arising,in which how to filter a large amount of information the network's remarks generated is a major difficulty. The traditional method of shiel-ding has low efficiency and is not accurate enough,so propose a new keyword shielding technology. Mainly use binary syntax model combined with layered hidden Markov model segmentation techniques,first utilize binary syntax model to get the constitute probability of the common words and keywords in a large corpus,creating a dictionary of common words and keywords classified,then combined casca-ding hidden Markov model for the specific sentence word processing,calculate the probability of its keywords shield for segmented result, finally get a scientific shielding probability,which can greatly improve the accuracy of keyword shield.%信息时代给人们的生活带来巨大改善,但同时也伴随一系列问题的产生,其中如何对网络中产生的大数据量的言论信息进行过滤的问题是研究的一大难点。传统的屏蔽法效率较低而且不够准确,因此文中提出了一种新的关键词屏蔽技术。主要采用二元语法模型结合层叠隐马可夫分词技术,首先运用二元语法模型在大量语料中得到普通词和关键词的构成概率,建立一个有普通词和关键词分类的词典,再结合层叠隐马可夫模型对具体句子进行分词处理,对分词后的结果计算其关键词屏蔽概率,最终得到一个科学的屏蔽概率,可以大大提高关键词屏蔽的准确性。

  6. Obtaining statistics of cascading line outages spreading in an electric transmission network from standard utility data

    CERN Document Server

    Dobson, Ian

    2015-01-01

    We show how to use standard transmission line outage historical data to obtain the network topology in such a way that cascades of line outages can be easily located on the network. Then we obtain statistics quantifying how cascading outages typically spread on the network. Processing real outage data is fundamental for understanding cascading and for evaluating the validity of the many different models and simulations that have been proposed for cascading in power networks.

  7. The Neurometabolic Cascade of Concussion

    National Research Council Canada - National Science Library

    Giza, Christopher C; Hovda, David A

    2001-01-01

    Data Synthesis: The primary elements of the pathophysiologic cascade following concussive brain injury include abrupt neuronal depolarization, release of excitatory neurotransmitters, ionic shifts, changes...

  8. Drifting through basic subprocesses of reading: A hierarchical diffusion model analysis of age effects on visual word recognition

    Directory of Open Access Journals (Sweden)

    Eva Froehlich

    2016-11-01

    Full Text Available Reading is one of the most popular leisure activities and it is routinely performed by most individuals even in old age. Successful reading enables older people to master and actively participate in everyday life and maintain functional independence. Yet, reading comprises a multitude of subprocesses and it is undoubtedly one of the most complex accomplishments of the human brain. Not surprisingly, findings of age-related effects on word recognition and reading have been partly contradictory and are often confined to only one of four central reading subprocesses, i.e., sublexical, orthographic, phonological and lexico-semantic processing. The aim of the present study was therefore to systematically investigate the impact of age on each of these subprocesses. A total of 1,807 participants (young, N = 384; old, N = 1,423 performed four decision tasks specifically designed to tap one of the subprocesses. To account for the behavioral heterogeneity in older adults, this subsample was split into high and low performing readers. Data were analyzed using a hierarchical diffusion modelling approach which provides more information than standard response times/accuracy analyses. Taking into account incorrect and correct response times, their distributions and accuracy data, hierarchical diffusion modelling allowed us to differentiate between age-related changes in decision threshold, non-decision time and the speed of information uptake. We observed longer non-decision times for older adults and a more conservative decision threshold. More importantly, high-performing older readers outperformed younger adults at the speed of information uptake in orthographic and lexico-semantic processing whereas a general age-disadvantage was observed at the sublexical and phonological levels. Low-performing older readers were slowest in information uptake in all four subprocesses. Discussing these results in terms of computational models of word recognition, we propose

  9. Drifting through Basic Subprocesses of Reading: A Hierarchical Diffusion Model Analysis of Age Effects on Visual Word Recognition

    Science.gov (United States)

    Froehlich, Eva; Liebig, Johanna; Ziegler, Johannes C.; Braun, Mario; Lindenberger, Ulman; Heekeren, Hauke R.; Jacobs, Arthur M.

    2016-01-01

    Reading is one of the most popular leisure activities and it is routinely performed by most individuals even in old age. Successful reading enables older people to master and actively participate in everyday life and maintain functional independence. Yet, reading comprises a multitude of subprocesses and it is undoubtedly one of the most complex accomplishments of the human brain. Not surprisingly, findings of age-related effects on word recognition and reading have been partly contradictory and are often confined to only one of four central reading subprocesses, i.e., sublexical, orthographic, phonological and lexico-semantic processing. The aim of the present study was therefore to systematically investigate the impact of age on each of these subprocesses. A total of 1,807 participants (young, N = 384; old, N = 1,423) performed four decision tasks specifically designed to tap one of the subprocesses. To account for the behavioral heterogeneity in older adults, this subsample was split into high and low performing readers. Data were analyzed using a hierarchical diffusion modeling approach, which provides more information than standard response time/accuracy analyses. Taking into account incorrect and correct response times, their distributions and accuracy data, hierarchical diffusion modeling allowed us to differentiate between age-related changes in decision threshold, non-decision time and the speed of information uptake. We observed longer non-decision times for older adults and a more conservative decision threshold. More importantly, high-performing older readers outperformed younger adults at the speed of information uptake in orthographic and lexico-semantic processing, whereas a general age-disadvantage was observed at the sublexical and phonological levels. Low-performing older readers were slowest in information uptake in all four subprocesses. Discussing these results in terms of computational models of word recognition, we propose age

  10. Forecasting Social Unrest Using Activity Cascades.

    Science.gov (United States)

    Cadena, Jose; Korkmaz, Gizem; Kuhlman, Chris J; Marathe, Achla; Ramakrishnan, Naren; Vullikanti, Anil

    2015-01-01

    Social unrest is endemic in many societies, and recent news has drawn attention to happenings in Latin America, the Middle East, and Eastern Europe. Civilian populations mobilize, sometimes spontaneously and sometimes in an organized manner, to raise awareness of key issues or to demand changes in governing or other organizational structures. It is of key interest to social scientists and policy makers to forecast civil unrest using indicators observed on media such as Twitter, news, and blogs. We present an event forecasting model using a notion of activity cascades in Twitter (proposed by Gonzalez-Bailon et al., 2011) to predict the occurrence of protests in three countries of Latin America: Brazil, Mexico, and Venezuela. The basic assumption is that the emergence of a suitably detected activity cascade is a precursor or a surrogate to a real protest event that will happen "on the ground." Our model supports the theoretical characterization of large cascades using spectral properties and uses properties of detected cascades to forecast events. Experimental results on many datasets, including the recent June 2013 protests in Brazil, demonstrate the effectiveness of our approach.

  11. Geothermal research, Oregon Cascades: Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Priest, G.R.; Black, G.L.

    1988-10-27

    Previous USDOE-funded geothermal studies have produced an extensive temperature gradient and heat flow data base for the State of Oregon. One of the important features identified as a result of these studies is a rapid transition from heat flow values on the order of 40 mW/m/sup 2/ in the Willamette Valley and Western Cascades to values of greater than or equal to100 mW/m/sup 2/ in the High Cascades and the eastern portion of the Western Cascades. These data indicate that the Cascade Range in Oregon has potential as a major geothermal province and stimulated much of the later work completed by government agencies and private industry. Additional data generated as a result of this grant and published in DOGAMI Open-File Report 0-86-2 further define the location and magnitude of this transition zone. In addition, abundant data collected from the vicinity of Breitenbush and Austin Hot Springs have permitted the formulation of relatively detailed models of these hydrothermal systems. These models are published in DOGAMI Open-File Report 0-88-5. Task 1.2 of the Deliverables section of Amendment M001 is fulfilled by DOGAMI publication GMS-48, Geologic map of the McKenzie Bridge quadrangle, Lane County, Oregon. This map was printed in October, 1988, and is part of the final submission to USDOE. 8 refs.

  12. Network reconstruction from infection cascades

    CERN Document Server

    Braunstein, Alfredo

    2016-01-01

    Reconstructing propagation networks from observations is a fundamental inverse problem, and it's crucial to understand and control dynamics in complex systems. Here we show that it is possible to reconstruct the whole structure of an interaction network and to simultaneously infer the complete time course of activation spreading, relying just on single snapshots of a small number of activity cascades. The method, that we called Inverse Dynamics Network Reconstruction (IDNR), is shown to work successfully on several synthetic and real networks, inferring the networks and the sources of infection based on sparse observations, including single snapshots. IDNR is built on a Belief Propagation approximation, that has an impressive performance in a wide variety of topological structures. The method can be applied in absence of complete time-series data by providing a detailed modeling of the posterior distribution of trajectories conditioned to the observations. Furthermore, we show by experiments that the informat...

  13. Cascades in interdependent flow networks

    CERN Document Server

    Scala, Antonio; Caldarelli, Guido; D'Agostino, Gregorio

    2015-01-01

    We investigate the abrupt breakdown behavior of coupled distribution grids under load growth. This scenario mimics the ever-increasing customer demand and the foreseen introduction of energy hubs interconnecting the different energy vectors. We extend an analytical model of cascading behavior due to line overloads to the case of interdependent networks and find evidence of first order transitions due to the long-range nature of the flows. Our results indicate that the foreseen increase in the couplings between the grids has two competing effects: on the one hand, it increases the safety region where grids can operate without withstanding systemic failures; on the other hand, it increases the possibility of a joint systems' failure.

  14. Availability Cascades & the Sharing Economy

    DEFF Research Database (Denmark)

    Netter, Sarah

    2014-01-01

    In search of a new concept that will provide answers to as to how modern societies should not only make sense but also resolve the social and environmental problems linked with our modes of production and consumption, collaborative consumption and the sharing economy are increasingly attracting...... attention. This conceptual paper attempts to explain the emergent focus on the sharing economy and associated business and consumption models by applying cascade theory. Risks associated with this behavior will be especially examined with regard to the sustainability claim of collaborative consumption....... With academics, practitioners, and civil society alike having a shared history in being rather fast in accepting new concepts that will not only provide business opportunities but also a good conscience, this study proposes a critical study of the implications of collaborative consumption, before engaging...

  15. Availability Cascades & the Sharing Economy

    DEFF Research Database (Denmark)

    Netter, Sarah

    2015-01-01

    In search of a new concept that will provide answers to as to how modern societies should not only make sense but also resolve the social and environmental problems linked with our modes of production and consumption, collaborative consumption and the sharing economy are increasingly attracting...... attention. This conceptual paper attempts to explain the emergent focus on the sharing economy and associated business and consumption models by applying cascade theory. Risks associated with this behavior will be especially examined with regard to the sustainability claim of collaborative consumption....... With academics, practitioners, and civil society alike having a shared history in being rather fast in accepting new concepts that will not only provide business opportunities but also a good conscience, this study proposes a critical study of the implications of collaborative consumption, before engaging...

  16. Process Models of Reading: Some Data on the Initiation of Processes.

    Science.gov (United States)

    1982-12-01

    Hunt, Frost & Lunnenborg, 1975; Hunt, Lunnenborg & Lewis, 1973; Perfetti & Lesgold, 1976). When only one word is presented at a time, yet every word is...reading. In A.M. Lesgold & C.A. Perfetti (Eds.), Interactive Processes in Reading. Hillsdale, NJ: Erlbaum, 1981. Norman, D.A. & Bobrow, D.G. On data...limited and resource limited procesees. Cognitive Psychology, 1975, 7, 44-64. Perfetti , C.A. & Lesgold, A.M. Discourse comprehension and sources of

  17. Statistical analysis of cascading failures in power grids

    Energy Technology Data Exchange (ETDEWEB)

    Chertkov, Michael [Los Alamos National Laboratory; Pfitzner, Rene [Los Alamos National Laboratory; Turitsyn, Konstantin [Los Alamos National Laboratory

    2010-12-01

    We introduce a new microscopic model of cascading failures in transmission power grids. This model accounts for automatic response of the grid to load fluctuations that take place on the scale of minutes, when optimum power flow adjustments and load shedding controls are unavailable. We describe extreme events, caused by load fluctuations, which cause cascading failures of loads, generators and lines. Our model is quasi-static in the causal, discrete time and sequential resolution of individual failures. The model, in its simplest realization based on the Directed Current description of the power flow problem, is tested on three standard IEEE systems consisting of 30, 39 and 118 buses. Our statistical analysis suggests a straightforward classification of cascading and islanding phases in terms of the ratios between average number of removed loads, generators and links. The analysis also demonstrates sensitivity to variations in line capacities. Future research challenges in modeling and control of cascading outages over real-world power networks are discussed.

  18. Un Programa Personalizado De Lectura En Un Aula Primaria: Reporte De Un Modelo Comprobado (A Personalized Program of Reading in a First Grade Classroom: Report From a Proven Model.)

    Science.gov (United States)

    Mendenhall, Susie B.; And Others

    This document written in Spanish describes a personalized reading program and discusses the results of its implementation. The focus of this approach to reading is based on the individual child and his feelings. This model personalizes the child's reading material in the classroom. In personalizing the reading material, the child's attitudes…

  19. Developmental changes in reading do not alter the development of visual processing skills: An application of explanatory item response models in grades K-2

    Directory of Open Access Journals (Sweden)

    Kristi L Santi

    2015-02-01

    Full Text Available Visual processing has been widely studied in regard to its impact on a students’ ability to read. A less researched area is the role of reading in the development of visual processing skills. A cohort-sequential, accelerated-longitudinal design was utilized with 932 kindergarten, first, and second grade students to examine the impact of reading acquisition on the processing of various types of visual discrimination and visual motor test items. Students were assessed four times per year on a variety of reading measures and reading precursors and two popular measures of visual processing over a three-year period. Explanatory item response models were used to examine the roles of person and item characteristics on changes in visual processing abilities and changes in item difficulties over time. Results showed different developmental patterns for five types of visual processing test items, but most importantly failed to show consistent effects of learning to read on changes in item difficulty. Thus, the present study failed to find support for the hypothesis that learning to read alters performance on measures of visual processing. Rather, visual processing and reading ability improved together over time with no evidence to suggest cross-domain influences from reading to visual processing. Results are discussed in the context of developmental theories of visual processing and brain-based research on the role of visual skills in learning to read.

  20. Amblyopic reading is crowded.

    Science.gov (United States)

    Levi, Dennis M; Song, Shuang; Pelli, Denis G

    2007-10-26

    We measure acuity, crowding, and reading in amblyopic observers to answer four questions. (1) Is reading with the amblyopic eye impaired because of larger required letter size (i.e., worse acuity) or larger required spacing (i.e., worse crowding)? The size or spacing required to read at top speed is called "critical". For each eye of seven amblyopic observers and the preferred eyes of two normal observers, we measure reading rate as a function of the center-to-center spacing of the letters in central and peripheral vision. From these results, we estimate the critical spacing for reading. We also measured traditional acuity for an isolated letter and the critical spacing for identifying a letter among other letters, which is the classic measure of crowding. For both normals and amblyopes, in both central and peripheral vision, we find that the critical spacing for reading equals the critical spacing for crowding. The identical critical spacings, and very different critical sizes, show that crowding, not acuity, limits reading. (2) Does amblyopia affect peripheral reading? No. We find that amblyopes read normally with their amblyopic eye except that abnormal crowding in the fovea prevents them from reading fine print. (3) Is the normal periphery a good model for the amblyopic fovea? No. Reading centrally, the amblyopic eye has an abnormally large critical spacing but reads all larger spacings at normal rates. This is unlike the normal periphery, in which both critical spacing and maximum reading rate are severely impaired relative to the normal fovea. (4) Can the uncrowded-span theory of reading rate explain amblyopic reading? Yes. The case of amblyopia shows that crowding limits reading solely by determining the uncrowded span: the number of characters that are not crowded. Characters are uncrowded if and only if their spacing is more than critical. The text spacing may be uniform, but the observer's critical spacing increases with distance from fixation, so the